WorldWideScience

Sample records for background particle concentrations

  1. 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.

  2. Variability of sub-micrometer particle number size distributions and concentrations in the Western Mediterranean regional background

    Directory of Open Access Journals (Sweden)

    Michael Cusack

    2013-02-01

    Full Text Available This study focuses on the daily and seasonal variability of particle number size distributions and concentrations, performed at the Montseny (MSY regional background station in the western Mediterranean from October 2010 to June 2011. Particle number concentrations at MSY were shown to be within range of various other sites across Europe reported in literature, but the seasonality of the particle number size distributions revealed significant differences. The Aitken mode is the dominant particle mode at MSY, with arithmetic mean concentrations of 1698 cm3, followed by the accumulation mode (877 cm−3 and the nucleation mode (246 cm−3. Concentrations showed a strong seasonal variability with large increases in particle number concentrations observed from the colder to warmer months. The modality of median size distributions was typically bimodal, except under polluted conditions when the size distribution was unimodal. During the colder months, the daily variation of particle number size distributions are strongly influenced by a diurnal breeze system, whereby the Aitken and accumulation modes vary similarly to PM1 and BC mass concentrations, with nocturnal minima and sharp day-time increases owing to the development of a diurnal mountain breeze. Under clean air conditions, high levels of nucleation and lower Aitken mode concentrations were measured, highlighting the importance of new particle formation as a source of particles in the absence of a significant condensation sink. During the warmer months, nucleation mode concentrations were observed to be relatively elevated both under polluted and clean conditions due to increased photochemical reactions, with enhanced subsequent growth owing to elevated concentrations of condensable organic vapours produced from biogenic volatile organic compounds, indicating that nucleation at MSY does not exclusively occur under clean air conditions. Finally, mixing of air masses between polluted and non

  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. Continuous flow dielectrophoretic particle concentrator

    Science.gov (United States)

    Cummings, Eric B [Livermore, CA

    2007-04-17

    A continuous-flow filter/concentrator for separating and/or concentrating particles in a fluid is disclosed. The filter is a three-port device an inlet port, an filter port and a concentrate port. The filter separates particles into two streams by the ratio of their dielectrophoretic mobility to their electrokinetic, advective, or diffusive mobility if the dominant transport mechanism is electrokinesis, advection, or diffusion, respectively.Also disclosed is a device for separating and/or concentrating particles by dielectrophoretic trapping of the particles.

  5. Novel Techniques for Background / Foreground Rejection in Particle Instruments

    Data.gov (United States)

    National Aeronautics and Space Administration — The Novel Techniques for Background / Foreground Rejection in Particle Instruments project addresses the need for signal contamination and background signal...

  6. Particle interactions in concentrated suspensions

    International Nuclear Information System (INIS)

    Mondy, L.A.; Graham, A.L.; Abbott, J.R.; Brenner, H.

    1993-01-01

    An overview is presented of research that focuses on slow flows of suspensions in which colloidal and inertial effects are negligibly small. The authors describe nuclear magnetic resonance imaging experiments to quantitatively measure particle migration occurring in concentrated suspensions undergoing a flow with a nonuniform shear rate. These experiments address the issue of how the flow field affects the microstructure of suspensions. In order to understand the local viscosity in a suspension with such a flow-induced, spatially varying concentration, one must know how the viscosity of a homogeneous suspension depends on such variables as solids concentration and particle orientation. The authors suggest the technique of falling ball viscometry, using small balls, as a method to determine the effective viscosity of a suspension without affecting the original microstructure significantly. They also describe data from experiments in which the detailed fluctuations of a falling ball's velocity indicate the noncontinuum nature of the suspension and may lead to more insights into the effects of suspension microstructure on macroscopic properties. Finally, they briefly describe other experiments that can be performed in quiescent suspensions (in contrast to the use of conventional shear rotational viscometers) in order to learn more about boundary effects in concentrated suspensions

  7. Background concentrations and fluxes of atmospheric ammonia overa deciduous forest

    DEFF Research Database (Denmark)

    Hansen, Kristina; Pryor, Sara C.; Bøgh, Eva

    2015-01-01

    to quantify the phase-partitioning and diagnose possible causes of upward NH3 fluxes. Data from 2013 combined with previous NH3 studies at this site indicate a seasonal background NH3 concentration of spring: 0.92 ± 0.95, summer: 0.30 ± 0.39, autumn: 0.20 ± 0.26, and winter: 0.26 ± 0.1 μg NH3-N m−3. Air mass...... back trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model did not indicate any directional bias in the measured NH3 concentration confirming the absence of strong local sources of NH3. The NH3 fluxes were mainly upward (emission) and had a magnitude of up to 0...

  8. Suspended sediment concentration and particle size distribution ...

    Indian Academy of Sciences (India)

    , zinc and nickel) transported in ... Suspended sediment concentration; heavy metal concentration; regression model; particle size distribution;. Kojour watershed; Iran. ..... contaminants in a uranium mine pite–Lake; Water Res. 39 3055–3061.

  9. Could unstable relic particles distort the microwave background radiation?

    International Nuclear Information System (INIS)

    Dar, A.; Loeb, A.; Nussinov, S.

    1989-01-01

    Three general classes of possible scenarios for the recently reported distortion of the microwave background radiation (MBR) via decaying relic weakly interacting particles are analyzed. The analysis shows that such particles could not reheat the universe and cause the spectral distortion of the MBR. Gravitational processes such as the early formation of massive black holes may still be plausible energy sources for producing the reported spectral distortion of the MBR at an early cosmological epoch. 24 references

  10. Effects of background music on concentration of workers.

    Science.gov (United States)

    Huang, Rong-Hwa; Shih, Yi-Nuo

    2011-01-01

    Background music is a common element in daily living and the workplace. Determination of whether background music affects human work concentration is a relevant concern. Studies have found background music influences human behavior, and this study attempts to understand how background music and listener fondness for types of music affects worker concentration. This study analyzes how different types of background music--and how listeners' degree of preference for the background music--can affect listener concentration in attention testing through Randomized Controlled Trial (RCT). Data were collected from 89 workers. The participants ranged in age between 19 and 28 years old, with an average age of 24 years old. We conclude background music influenced listener attention. This influence has more to do with listener fondness for the music than with type of music. Compared to situations without background music, the likelihood of background music affecting test-taker attention performance is likely to increase with the degree to which the test-taker likes or dislikes the music. It is important not to select music that workers strongly like or dislike when making a selection of background music to avoid negatively affecting worker concentration.

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

    International Nuclear Information System (INIS)

    Panek, M.

    1987-06-01

    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

  12. Can decaying particle explain cosmic infrared background excess?

    Directory of Open Access Journals (Sweden)

    Kazunori Kohri

    2017-09-01

    Full Text Available Recently the CIBER experiment measured the diffuse cosmic infrared background (CIB flux and claimed an excess compared with integrated emission from galaxies. We show that the CIB spectrum can be fitted by the additional photons produced by the decay of a new particle. However, it also contributes too much to the anisotropy of the CIB, which is in contradiction with the anisotropy measurements by the CIBER and Hubble Space Telescope.

  13. Benchmarking the Particle Background in the LHC Experiments

    CERN Document Server

    Gschwendtner, E

    2000-01-01

    The experiments for the Large Hadron Collider LHC at CERN have to work for 15 years in the presence of a very high particle background of photons in the energy range from 100\\,keV to 10\\,MeV and neutrons in the range from thermal energies ($\\approx 0.025\\,$eV) to 20\\,MeV. \\\\ The background is so high that it becomes a major design criterion for the ATLAS ex\\-peri\\-ment, a general purpose experiment at LHC that will be operational in the year 2005. The exact level of this background is poorly known. At present an uncertainty factor of five has to be assumed to which the limited knowledge of the shower processes in the absorber material and the ensueing neutron and photon production is estimated to contribute with a factor 2.5. \\\\ So far, the background has been assessed only through extensive Monte Carlo evaluation with the particle transport code FLUKA. The lack of relevant measurements, which were not done up to now, are to a large extent responsible for this uncertainty. Hence it is essential to benchmark t...

  14. 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.

  15. Acoustic concentration of particles in fluid flow

    Science.gov (United States)

    Ward, Michael W.; Kaduchak, Gregory

    2017-08-15

    Disclosed herein is a acoustic concentration of particles in a fluid flow that 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.

  16. Preliminary background radon and radon progeny concentrations at North Ranger

    Energy Technology Data Exchange (ETDEWEB)

    Auty, R.; Du Preez, H. [Energy Resources of Australia Ltd., Jabiru, NT (Australia). Safety, Health and Radiation Protection Dept.

    1994-12-31

    The aim of this study was to determine background concentrations due to radon ({sup 222}Rn) and radon progeny at the North Ranger lease and proposed transport corridor. The results of this study would assist in establishing rehabilitation standards. Airborne {sup 222}Rn and short lived products vary significantly over a period of time. These variations are primarily due to changes in meteorological conditions. A program was set up to monitor radon and radon progeny concentrations over an extensive period of time so that diurnal and seasonal variations could be assessed. This paper outlines the methodologies, instrumentation, current results and proposed work. 3 refs., 4 tabs.

  17. Measuring the cosmological background of relativistic particles with WMAP

    CERN Document Server

    Crotty, P; Pastor, S; Crotty, Patrick; Lesgourgues, Julien; Pastor, Sergio

    2003-01-01

    We show that the first year results of the Wilkinson Microwave Anisotropy Probe (WMAP) constrain very efficiently the energy density in relativistic particles in the universe. We derive new bounds on additional relativistic degrees of freedom expressed in terms of an excess in the effective number of light neutrinos Delta N_eff. Within the flat LambdaCDM scenario, the allowed range is Delta N_eff < 6 (95% CL) using WMAP data only, or -2.6 < Delta N_eff < 4 with the prior H_0= 72 \\pm 8 km/s/Mpc. When other cosmic microwave background and large scale structure experiments are taken into account, the window shrinks to -1.5 < Delta N_eff < 4.2. These results are in perfect agreement with the bounds from primordial nucleosynthesis. Non-minimal cosmological models with extra relativistic degrees of freedom are now severely restricted.

  18. Controls on hourly variations in urban background air pollutant concentrations

    Science.gov (United States)

    Moreno, Teresa; Lavín, Javier; Querol, Xavier; Alastuey, Andrés; Viana, Mar; Gibbons, Wes

    Average 21st century concentrations of urban air pollutants linked to cardiorespiratory disease are not declining, and commonly exceed legal limits. Even below such limits, health effects are being observed and may be related to transient daytime peaks in pollutant concentrations. With this in mind, we analyse >52,000 hourly urban background readings of PM 10 and pollutant gases throughout 2007 at a European town with legal annual average concentrations of common pollutants, but with a documented air pollution-related cardiorespiratory health problem, and demonstrate the hourly variations in PM 10, SO 2, NO x, CO and O 3. Back-trajectory analysis was applied to track the arrival of exotic PM 10 intrusions, the main controls on air pollutants were identified, and the typical hourly pattern on ambient concentrations during 2007 was profiled. Emphasis was placed on "worst case" data (>90th percentile), when health effects are likely to be greatest. The data show marked daytime variations in pollutants result from rush-hour traffic-related pollution spikes, midday industrial SO 2 maxima, and afternoon O 3 peaks. African dust intrusions enhance PM 10 levels at whatever hour, whereas European PM incursions produce pronounced evening peaks due to their transport direction (across an industrial traffic corridor). Transient peak profiling moves us closer to the reality of personal outdoor exposure to inhalable pollutants in a given urban area. We argue that such an approach to monitoring data potentially offers more to air pollution health effect studies than using only 24 h or annual averages.

  19. Maximum Permissible Concentrations and Negligible Concentrations for metals, taking background concentrations into account

    NARCIS (Netherlands)

    Crommentuijn T; Polder MD; Plassche EJ van de; CSR

    1997-01-01

    Maximum Permissible Concentrations (MPCs) and Negligible Concentrations (NCs) have been derived for a series of heavy metals. For some of the metals, the Ministry of Housing, Spatial Planning and the Environment (VROM) used earlier MPCs and NCs to set Environmental Quality Objectives for water,

  20. 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.

  1. Concentration and size distribution of particles in abstracted groundwater.

    Science.gov (United States)

    van Beek, C G E M; de Zwart, A H; Balemans, M; Kooiman, J W; van Rosmalen, C; Timmer, H; Vandersluys, J; Stuyfzand, P J

    2010-02-01

    Particle number concentrations have been counted and particle size distributions calculated in groundwater derived by abstraction wells. Both concentration and size distribution are governed by the discharge rate: the higher this rate the higher the concentration and the higher the proportion of larger particles. However, the particle concentration in groundwater derived from abstraction wells, with high groundwater flow velocities, is much lower than in groundwater from monitor wells, with minimal flow velocities. This inconsistency points to exhaustion of the particle supply in the aquifer around wells due to groundwater abstraction for many years. The particle size distribution can be described with the help of a power law or Pareto distribution. Comparing the measured particle size distribution with the Pareto distribution shows that particles with a diameter >7 microm are under-represented. As the particle size distribution is dependent on the flow velocity, so is the value of the "Pareto" slope beta. (c) 2009 Elsevier Ltd. All rights reserved.

  2. 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.

  3. Concentration and size distribution of particles in abstracted groundwater

    NARCIS (Netherlands)

    Van Beek, C.G.E.M.; de Zwart, A.H.; Balemans, M.; Kooiman, J.W.; van Rosmalen, C.; Timmer, H.; Vandersluys, J.; Stuijfzand, P.J.

    2010-01-01

    Particle number concentrations have been counted and particle size distributions calculated in groundwater derived by abstraction wells. Both concentration and size distribution are governed by the discharge rate: the higher this rate the higher the concentration and the higher the proportion of

  4. Workplace aerosol mass concentration measurement using optical particle counters.

    Science.gov (United States)

    Görner, Peter; Simon, Xavier; Bémer, Denis; Lidén, Göran

    2012-02-01

    Direct-reading aerosol measurement usually uses the optical properties of airborne particles to detect and measure particle concentration. In the case of occupational hygiene, mass concentration measurement is often required. Two aerosol monitoring methods are based on the principle of light scattering: optical particle counting (OPC) and photometry. The former analyses the light scattered by a single particle, the latter by a cloud of particles. Both methods need calibration to transform the quantity of scattered light detected into particle concentration. Photometers are simpler to use and can be directly calibrated to measure mass concentration. However, their response varies not only with aerosol concentration but also with particle size distribution, which frequently contributes to biased measurement. Optical particle counters directly measure the particle number concentration and particle size that allows assessment of the particle mass provided the particles are spherical and of known density. An integrating algorithm is used to calculate the mass concentration of any conventional health-related aerosol fraction. The concentrations calculated thus have been compared with simultaneous measurements by conventional gravimetric sampling to check the possibility of field OPC calibration with real workplace aerosols with a view to further monitoring particle mass concentration. Aerosol concentrations were measured in the food industry using the OPC GRIMM® 1.108 and the CIP 10-Inhalable and CIP 10-Respirable (ARELCO®) aerosol samplers while meat sausages were being brushed and coated with calcium carbonate. Previously, the original OPC inlet had been adapted to sample inhalable aerosol. A mixed aerosol of calcium carbonate and fungi spores was present in the workplace. The OPC particle-size distribution and an estimated average particle density of both aerosol components were used to calculate the mass concentration. The inhalable and respirable aerosol fractions

  5. 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

    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...... species in both particle and gas phase. The total number of analyzed ship plumes was 726, covering on average 19% of the time when air masses were arriving at the site over the shipping lane. During the periods when plumes were present, the particle concentration exceeded the background values on average...... the ship plume contribution to the total particle number and PM0.15 mass concentration (mass of particles below 150 nm in diameter, converted from volume assuming sphericity) at the site. The method is not limited to particle number or volume concentration, but can also be used for different chemical...

  6. Suspended sediment concentration and particle size distribution ...

    Indian Academy of Sciences (India)

    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 ...

  7. 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....

  8. Key Features of New Particle Formation Events at Background Sites in China

    Science.gov (United States)

    Shen, X.; Sun, J.; Zhang, X.; Zhang, Y.

    2016-12-01

    Long-term continuous measurements of particle number size distributions with mobility diameter sizes ranging from 3 to 800 nm were performed to study new particle formation (NPF) events at Shangdianzi (SDZ), Mt. Tai (TS), and Lin'an (LAN) stations representing the background atmospheric conditions in the North China Plain (NCP), Central East China (CEC), and Yangtze River Delta (YRD) regions, respectively. The mean formation rate of 3-nm particles was 6.3, 3.7, and 5.8 cm-3 s-1, and the mean particle growth rate was 3.6, 6.0, and 6.2 nm h-1at SDZ, TS, and LAN, respectively. The NPF event characteristics at the three sites indicate that there may be a stronger source of low volatile vapors and higher condensational sink of pre-existing particles in the YRD region. The formation rate of NPF events at these sites, as well as the condensation sink, is approximately 10 times higher than some results reported at rural/urban sites in western countries. However, the growth rates appear to be 1-2 times higher. Approximately 12%-17% of all NPF events with nucleated particles grow to a climate relevant size (>50 nm). These kinds of NPF events were normally observed with higher growth rate than the other NPF cases. Generally, the cloud condensation nuclei (CCN) number concentration can be enhanced by approximately a factor of 2-6 on these event days. The mean value of the enhancement factor is lowest at LAN (2-3) and highest at SDZ ( 4). NPF events have also been found to have greater impact on CCN production in China at the regional scale than in the other background sites worldwide. Based on the long-term measurement of NPF event at SDZ station (8-year dataset), it was found the first factor in determining the NPF occurrence was the condensation sink, and the second factor could be the concentration level of precursor vapors participating in the NPF event (e.g., sulfuric acid). Some emission control strategies applied in China will reduce the condensation sink, which is

  9. Particle size- and concentration-dependent separation of magnetic nanoparticles

    International Nuclear Information System (INIS)

    Witte, Kerstin; Müller, Knut; Grüttner, Cordula; Westphal, Fritz; Johansson, Christer

    2017-01-01

    Small magnetic nanoparticles with a narrow size distribution are of great interest for several biomedical applications. When the size of the particles decreases, the magnetic moment of the particles decreases. This leads to a significant increase in the separation time by several orders of magnitude. Therefore, in the present study the separation processes of bionized nanoferrites (BNF) with different sizes and concentrations were investigated with the commercial Sepmag Q system. It was found that an increasing initial particle concentration leads to a reduction of the separation time for large nanoparticles due to the higher probability of building chains. Small nanoparticles showed exactly the opposite behavior with rising particle concentration up to 0.1 mg(Fe)/ml. For higher iron concentrations the separation time remains constant and the measured Z-average decreases in the supernatant at same time intervals. At half separation time a high yield with decreasing hydrodynamic diameter of particles can be obtained using higher initial particle concentrations. - Highlights: • Size dependent separation processes of multicore nanoparticles. • Concentration dependent separation processes of multicore nanoparticles. • Increasing separation time with rising concentrations for small particles. • Large particles show typical cooperative magnetophoresis behavior.

  10. Particle size- and concentration-dependent separation of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Witte, Kerstin, E-mail: witte@micromod.de [University of Rostock, Institute of Physics, Albert-Einstein-Str. 23, 18059 Rostock (Germany); Micromod Partikeltechnologie GmbH, Friedrich-Barnewitz-Str. 4, 18119 Rostock (Germany); Müller, Knut; Grüttner, Cordula; Westphal, Fritz [Micromod Partikeltechnologie GmbH, Friedrich-Barnewitz-Str. 4, 18119 Rostock (Germany); Johansson, Christer [Acreo Swedish ICT AB, 40014 Göteborg (Sweden)

    2017-04-01

    Small magnetic nanoparticles with a narrow size distribution are of great interest for several biomedical applications. When the size of the particles decreases, the magnetic moment of the particles decreases. This leads to a significant increase in the separation time by several orders of magnitude. Therefore, in the present study the separation processes of bionized nanoferrites (BNF) with different sizes and concentrations were investigated with the commercial Sepmag Q system. It was found that an increasing initial particle concentration leads to a reduction of the separation time for large nanoparticles due to the higher probability of building chains. Small nanoparticles showed exactly the opposite behavior with rising particle concentration up to 0.1 mg(Fe)/ml. For higher iron concentrations the separation time remains constant and the measured Z-average decreases in the supernatant at same time intervals. At half separation time a high yield with decreasing hydrodynamic diameter of particles can be obtained using higher initial particle concentrations. - Highlights: • Size dependent separation processes of multicore nanoparticles. • Concentration dependent separation processes of multicore nanoparticles. • Increasing separation time with rising concentrations for small particles. • Large particles show typical cooperative magnetophoresis behavior.

  11. Radon Daughters Background Reduction in Alpha Particles Counting System

    International Nuclear Information System (INIS)

    Dadon, S. S.; Pelled, O.; Orion, I.

    2014-01-01

    The ABPC method is using a serially occurring events of the beta decay of the 214Bi fallow by alpha decay of the 214Po that take place almost simultaneously to detect the Pseudo Coincidence Event (PCE) from the RDP, and to subtract them from the gross alpha counts. 267 This work showed that it is possible to improve the efficiency of RDP background reduction, including subtracting the 218Po contribution by using the ABPC method based on a single solid state silicon PIPS detector. False counts percentage obtained at the output of the PCE circuit were smaller than 0.1%. The results show that the PCE circuit was not influenced by non RDP alpha emitters. The PCE system did not reduce the non PCE of the 218Po. After 20 minutes the 218Po was strongly decayed, and its contribution became negligible. In order to overcome this disadvantage, a mathematical matching calculations for the 214Po and the 218Po decay equations were employed, and a constant ratio of the APo214(0) / APo218(0) was obtained. This ratio can be used to estimate the count rate of the 218Po at the first 20 minutes, and to subtract it from the total count rate in order to obtain correct RDP reduction

  12. Contribution from indoor sources to particle number and mass concentrations in residential houses

    Science.gov (United States)

    He, Congrong; Morawska, Lidia; Hitchins, Jane; Gilbert, Dale

    As part of a large study investigating indoor air in residential houses in Brisbane, Australia, the purpose of this work was to quantify emission characteristics of indoor particle sources in 15 houses. Submicrometer particle number and approximation of PM 2.5 concentrations were measured simultaneously for more than 48 h in the kitchen of all the houses by using a condensation particle counter (CPC) and a photometer (DustTrak), respectively. In addition, characterizations of particles resulting from cooking conducted in an identical way in all the houses were measured by using a scanning mobility particle sizer (SMPS), an aerodynamic particle sizer (APS) and a DustTrak. All the events of elevated particle concentrations were linked to indoor activities using house occupants diary entries, and catalogued into 21 different types of indoor activities. This enabled quantification of the effect of indoor sources on indoor particle concentrations as well as quantification of emission rates from the sources. For example, the study found that frying, grilling, stove use, toasting, cooking pizza, cooking, candle vaporizing eucalyptus oil and fan heater use, could elevate the indoor submicrometer particle number concentration levels by more than five times, while PM 2.5 concentrations could be up to 3, 30 and 90 times higher than the background levels during smoking, frying and grilling, respectively.

  13. Effects of background neutral particles on a field-reversed configuration plasma in the translation process

    International Nuclear Information System (INIS)

    Matsuzawa, Yoshiki; Asai, Tomohiko; Takahashi, Tsutomu; Takahashi, Toshiki

    2008-01-01

    A field-reversed configuration (FRC) plasma was translated into a weakly ionized plasma and the effects of heating and particle buildup of the FRC plasma due to the background neutral particles and plasma injection in the translation process were investigated. Improvement of the particle and poloidal flux confinements and delay of onset of n=2 rotational instability were observed in the translation process. It was found that the internal structure of the plasma pressure (plasma temperature and density) at the separatrix and field null was deformed by the particle injection. FRC plasma translation through the background particles was equivalent to an end-on particle beam injection to the FRC plasma. Particles and energy were supplied during the translation. The results obtained for the phenomena of particle supply and plasma heating were also supported by the results of two-dimensional particle simulation. The effects of background particle injection appear to be a promising process for the regeneration of translation kinetic energy to plasma internal energy

  14. Saharan Dust Particle Size And Concentration Distribution In Central Ghana

    Science.gov (United States)

    Sunnu, A. K.

    2010-12-01

    A.K. Sunnu*, G. M. Afeti* and F. Resch+ *Department of Mechanical Engineering, Kwame Nkrumah University of Science and Technology (KNUST) Kumasi, Ghana. E-mail: albertsunnu@yahoo.com +Laboratoire Lepi, ISITV-Université du Sud Toulon-Var, 83162 La Valette cedex, France E-mail: resch@univ-tln.fr Keywords: Atmospheric aerosol; Saharan dust; Particle size distributions; Particle concentrations. Abstract The Saharan dust that is transported and deposited over many countries in the West African atmospheric environment (5°N), every year, during the months of November to March, known locally as the Harmattan season, have been studied over a 13-year period, between 1996 and 2009, using a location at Kumasi in central Ghana (6° 40'N, 1° 34'W) as the reference geographical point. The suspended Saharan dust particles were sampled by an optical particle counter, and the particle size distributions and concentrations were analysed. The counter gives the total dust loads as number of particles per unit volume of air. The optical particle counter used did not discriminate the smoke fractions (due to spontaneous bush fires during the dry season) from the Saharan dust. Within the particle size range measured (0.5 μm-25 μm.), the average inter-annual mean particle diameter, number and mass concentrations during the northern winter months of January and February were determined. The average daily number concentrations ranged from 15 particles/cm3 to 63 particles/cm3 with an average of 31 particles/cm3. The average daily mass concentrations ranged from 122 μg/m3 to 1344 μg/m3 with an average of 532 μg/m3. The measured particle concentrations outside the winter period were consistently less than 10 cm-3. The overall dust mean particle diameter, analyzed from the peak representative Harmattan periods over the 13-year period, ranged from 0.89 μm to 2.43 μm with an average of 1.5 μm ± 0.5. The particle size distributions exhibited the typical distribution pattern for

  15. Non-relativistic spinning particle in a Newton-Cartan background

    Science.gov (United States)

    Barducci, Andrea; Casalbuoni, Roberto; Gomis, Joaquim

    2018-01-01

    We construct the action of a non-relativistic spinning particle moving in a general torsionless Newton-Cartan background. The particle does not follow the geodesic equations, instead the motion is governed by the non-relativistic analog of Papapetrou equation. The spinning particle is described in terms of Grassmann variables. In the flat case the action is invariant under the non-relativistic analog of space-time vector supersymmetry.

  16. Hybrid electrokinetics for separation, mixing, and concentration of colloidal particles

    International Nuclear Information System (INIS)

    Sin, Mandy L Y; Shimabukuro, Yusuke; Wong, Pak Kin

    2009-01-01

    The advent of nanotechnology has facilitated the preparation of colloidal particles with adjustable sizes and the control of their size-dependent properties. Physical manipulation, such as separation, mixing, and concentration, of these colloidal particles represents an essential step for fully utilizing their potential in a wide spectrum of nanotechnology applications. In this study, we investigate hybrid electrokinetics, the combination of dielectrophoresis and electrohydrodynamics, for active manipulation of colloidal particles ranging from nanometers to micrometers in size. A concentric electrode configuration, which is optimized for generating electrohydrodynamic flow, has been designed to elucidate the effectiveness of hybrid electrokinetics and define the operating regimes for different microfluidic operations. The results indicate that the relative importance of electrohydrodynamics increases with decreasing particle size as predicted by a scaling analysis and that electrohydrodynamics is pivotal for manipulating nanoscale particles. Using the concentric electrodes, we demonstrate separation, mixing, and concentration of colloidal particles by adjusting the relative strengths of different electrokinetic phenomena. The effectiveness of hybrid electrokinetics indicates its potential to serve as a generic technique for active manipulation of colloidal particles in various nanotechnology applications.

  17. Source contributions to atmospheric fine carbon particle concentrations

    Science.gov (United States)

    Andrew Gray, H.; Cass, Glen R.

    A Lagrangian particle-in-cell air quality model has been developed that facilitates the study of source contributions to atmospheric fine elemental carbon and fine primary total carbon particle concentrations. Model performance was tested using spatially and temporally resolved emissions and air quality data gathered for this purpose in the Los Angeles area for the year 1982. It was shown that black elemental carbon (EC) particle concentrations in that city were dominated by emissions from diesel engines including both on-highway and off-highway applications. Fine primary total carbon particle concentrations (TC=EC+organic carbon) resulted from the accumulation of small increments from a great variety of emission source types including both gasoline and diesel powered highway vehicles, stationary source fuel oil and gas combustion, industrial processes, paved road dust, fireplaces, cigarettes and food cooking (e.g. charbroilers). Strategies for black elemental carbon particle concentration control will of necessity need to focus on diesel engines, while controls directed at total carbon particle concentrations will have to be diversified over a great many source types.

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

    OpenAIRE

    Casey B. Hall; Huiting Mao; Zhuyun Ye; Robert Talbot; Aijun Ding; Yang Zhang; Jialei Zhu; Tijian Wang; Che-Jen Lin; Congbin Fu; Xiuqun Yang

    2014-01-01

    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 a...

  19. Preferrential Concentration of Particles in Protoplanetary Nebula Turbulence

    Science.gov (United States)

    Hartlep, Thomas; Cuzzi, Jeffrey N.

    2015-01-01

    Preferential concentration in turbulence is a process that causes inertial particles to cluster in regions of high strain (in-between high vorticity regions), with specifics depending on their stopping time or Stokes number. This process is thought to be of importance in various problems including cloud droplet formation and aerosol transport in the atmosphere, sprays, and also in the formation of asteroids and comets in protoplanetary nebulae. In protoplanetary nebulae, the initial accretion of primitive bodies from freely-floating particles remains a problematic subject. Traditional growth-by-sticking models encounter a formidable "meter-size barrier" [1] in turbulent nebulae. One scenario that can lead directly from independent nebula particulates to large objects, avoiding the problematic m-km size range, involves formation of dense clumps of aerodynamically selected, typically mm-size particles in protoplanetary turbulence. There is evidence that at least the ordinary chondrite parent bodies were initially composed entirely of a homogeneous mix of such particles generally known as "chondrules" [2]. Thus, while it is arcane, turbulent preferential concentration acting directly on chondrule size particles are worthy of deeper study. Here, we present the statistical determination of particle multiplier distributions from numerical simulations of particle-laden isotopic turbulence, and a cascade model for modeling turbulent concentration at lengthscales and Reynolds numbers not accessible by numerical simulations. We find that the multiplier distributions are scale dependent at the very largest scales but have scale-invariant properties under a particular variable normalization at smaller scales.

  20. Simplified confocal microscope for counting particles at low concentrations.

    Science.gov (United States)

    Skinner, Joseph P; Swift, Kerry M; Ruan, Qiaoqiao; Perfetto, Sergio; Gratton, Enrico; Tetin, Sergey Y

    2013-07-01

    We describe a compact scanning confocal fluorescence microscope capable of detecting particles concentrations less than 100 particles∕ml in ~15 min. The system mechanically moves a cuvette containing ~3 ml of sample. A relatively large confocal volume is observed within the cuvette using a 1 mm pinhole in front of a detection PMT. Due to the motion of the sample, particles traverse the confocal volume quickly, and analysis by pattern recognition qualifies spikes in the emission intensity data and counts them as events. We show linearity of detection as a function of concentration and also characterize statistical behavior of the instrument. We calculate a detection sensitivity of the system using 3 μm fluorescent microspheres to be 5 particles/ml. Furthermore, to demonstrate biological application, we performed a dilution series to quantify stained E. coli and yeast cells. We counted E. coli cells at a concentration as low as 30 cells∕ml in 10 min/sample.

  1. Generalized Ohm's law for a background plasma in the presence of relativistic charged particles.

    Science.gov (United States)

    Sherlock, M

    2010-05-21

    A generalized Ohm's law is derived for a system composed of a background magnetohydrodynamic plasma and a lower density relativistic charged-particle distribution. The interpretation of Ohmic electric fields occurring due to force balance breaks down for such a system and instead an approach based on Maxwell's equations along with the particle flux equations is necessary. Three additional terms arise in Ohm's law and each is verified numerically.

  2. High energy particle background at neutron spallation sources and possible solutions

    Science.gov (United States)

    Cherkashyna, N.; Kanaki, K.; Kittelmann, T.; Filges, U.; Deen, P.; Herwig, K.; Ehlers, G.; Greene, G.; Carpenter, J.; Connatser, R.; Hall-Wilton, R.; Bentley, P. M.

    2014-07-01

    Modern spallation neutron sources are driven by proton beams ~ GeV energies. Whereas low energy particle background shielding is well understood for reactors sources of neutrons (~20 MeV), for high energies (100s MeV to multiple GeV) there is potential to improve shielding solutions and reduce instrument backgrounds significantly. We present initial measured data on high energy particle backgrounds, which illustrate the results of particle showers caused by high energy particles from spallation neutron sources. We use detailed physics models of different materials to identify new shielding solutions for such neutron sources, including laminated layers of multiple materials. In addition to the steel and concrete, which are used traditionally, we introduce some other options that are new to the neutron scattering community, among which there are copper alloys as used in hadronic calorimeters in high energy physics laboratories. These concepts have very attractive energy absorption characteristics, and simulations predict that the background suppression could be improved by one or two orders of magnitude. These solutions are expected to be great benefit to the European Spallation Source, where the majority of instruments are potentially affected by high energy backgrounds, as well as to existing spallation sources.

  3. 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.

  4. System for concentrating and analyzing particles suspended in a fluid

    Science.gov (United States)

    Fiechtner, Gregory J [Bethesda, MD; Cummings, Eric B [Livermore, CA; Singh, Anup K [Danville, CA

    2011-04-26

    Disclosed is a device for separating and concentrating particles suspended in a fluid stream by using dielectrophoresis (DEP) to trap and/or deflect those particles as they migrate through a fluid channel. The method uses fluid channels designed to constrain a liquid flowing through it to uniform electrokinetic flow velocities. This behavior is achieved by connecting deep and shallow sections of channels, with the channel depth varying abruptly along an interface. By careful design of abrupt changes in specific permeability at the interface, an abrupt and spatially uniform change in electrokinetic force can be selected. Because these abrupt interfaces also cause a sharp gradient in applied electric fields, a DEP force also can be established along the interface. Depending on the complex conductivity of the suspended particles and the immersion liquid, the DEP force can controllably complement or oppose the local electrokinetic force transporting the fluid through the channel allowing for manipulation of particles suspended in the transporting liquid.

  5. Ultrasonic spectrum for particle concentration measurement in multicomponent suspensions

    International Nuclear Information System (INIS)

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

    2016-01-01

    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. (paper)

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

    NARCIS (Netherlands)

    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

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

    Science.gov (United States)

    Lin, Jonathan; Jain, Sonia; Sun, Xiaoying; Liu, Victoria; Sato, Yuichiro Z.; Jimenez-Fernandez, Susan; Newfield, Ron S.; Pourfarzib, Ray; Tremoulet, Adriana H.; Gordon, John B.; Daniels, Lori B.; Burns, Jane C.

    2014-01-01

    Objective To test the hypothesis that children and adults with history of Kawasaki disease (KD) are more likely to have abnormal lipoprotein particle profiles that could place them at increased risk of 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 (P) concentrations and sizes were measured by Nuclear Magnetic Resonance (NMR) spectroscopy (Liposcience Inc., Raleigh, NC) and serum was assayed for total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDL)-C. Low-density lipoprotein cholesterol (LDL)-C was estimated using the Friedewald formula. Data were analyzed in a least-square means model adjusting for age and sex and using Holm correction for multiple comparisons. Results Compared with respective control groups, both adult and pediatric subjects with KD had significantly lower mean very-low-density lipoprotein-chylomicron particle concentrations (VLDLC-P), intermediate-density lipoproteins (IDL), TG, and TC concentrations. Pediatric subjects with KD had significantly lower LDL-P and LDL-C concentrations and lower mean TC/HDL-C ratio (ppediatric and adult subjects with KD regardless of their aneurysm status are no more likely than age-similar, healthy controls to have lipid patterns associated with increased risk of atherosclerosis. PMID:25039043

  8. A population-based approach to background discrimination in particle physics

    International Nuclear Information System (INIS)

    Colecchia, Federico

    2012-01-01

    Background properties in experimental particle physics are typically estimated from control samples corresponding to large numbers of events. This can provide precise knowledge of average background distributions, but typically does not take into account statistical fluctuations in a data set of interest. A novel approach based on mixture model decomposition is presented, as a way to extract additional information about statistical fluctuations from a given data set with a view to improving on knowledge of background distributions obtained from control samples. Events are treated as heterogeneous populations comprising particles originating from different processes, and individual particles are mapped to a process of interest on a probabilistic basis. The proposed approach makes it possible to estimate features of the background distributions from the data, and to extract information about statistical fluctuations that would otherwise be lost using traditional supervised classifiers trained on high-statistics control samples. A feasibility study on Monte Carlo is presented, together with a comparison with existing techniques. Finally, the prospects for the development of tools for intensive offline analysis of individual interesting events at the Large Hadron Collider are discussed.

  9. 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.

  10. Ice-nucleating particle concentrations unaffected by urban air pollution in Beijing, China

    Science.gov (United States)

    Chen, Jie; Wu, Zhijun; Augustin-Bauditz, Stefanie; Grawe, Sarah; Hartmann, Markus; Pei, Xiangyu; Liu, Zirui; Ji, Dongsheng; Wex, Heike

    2018-03-01

    Exceedingly high levels of PM2.5 with complex chemical composition occur frequently in China. It has been speculated whether anthropogenic PM2.5 may significantly contribute to ice-nucleating particles (INP). However, few studies have focused on the ice-nucleating properties of urban particles. In this work, two ice-nucleating droplet arrays have been used to determine the atmospheric number concentration of INP (NINP) in the range from -6 to -25 °C in Beijing. No correlations between NINP and either PM2.5 or black carbon mass concentrations were found, although both varied by more than a factor of 30 during the sampling period. Similarly, there were no correlations between NINP and either total particle number concentration or number concentrations for particles with diameters > 500 nm. Furthermore, there was no clear difference between day and night samples. All these results indicate that Beijing air pollution did not increase or decrease INP concentrations in the examined temperature range above values observed in nonurban areas; hence, the background INP concentrations might not be anthropogenically influenced as far as urban air pollution is concerned, at least in the examined temperature range.

  11. Air pollutant concentrations near three Texas roadways, Part I: Ultrafine particles

    Science.gov (United States)

    Zhu, Yifang; Pudota, Jayanth; Collins, Donald; Allen, David; Clements, Andrea; DenBleyker, Allison; Fraser, Matt; Jia, Yuling; McDonald-Buller, Elena; Michel, Edward

    Vehicular emitted air pollutant concentrations were studied near three types of roadways in Austin, Texas: (1) State Highway 71 (SH-71), a heavily traveled arterial highway dominated by passenger vehicles; (2) Interstate 35 (I-35), a limited access highway north of Austin in Georgetown; and (3) Farm to Market Road 973 (FM-973), a heavily traveled surface roadway dominated by truck traffic. Air pollutants examined include carbon monoxide (CO), oxides of nitrogen (NO x), and carbonyl species in the gas-phase. In the particle phase, ultrafine particle (UFP) concentrations (diameter road were found to be the most important factors determining UFP concentrations near the roadways. Since wind directions were not consistent during the sampling periods, distances along wind trajectories from the roadway to the sampling points were used to study the decay characteristics of UFPs. Under perpendicular wind conditions, for all studied roadway types, particle number concentrations increased dramatically moving from the upwind side to the downwind side. The elevated particle number concentrations decay exponentially with increasing distances from the roadway with sharp concentration gradients observed within 100-150 m, similar to previously reported studies. A single exponential decay curve was found to fit the data collected from all three roadways very well under perpendicular wind conditions. No consistent pattern was observed for UFPs under parallel wind conditions. However, regardless of wind conditions, particle concentrations returned to background levels within a few hundred meters of the roadway. Within measured UFP size ranges, smaller particles (6-25 nm) decayed faster than larger ones (100-300 nm). Similar decay rates were observed among UFP number, surface, and volume.

  12. 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.

  13. 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.

  14. Total mass and concentration of particles in dust clouds

    International Nuclear Information System (INIS)

    Gutmacher, R.G.; Higgins, G.H.; Tewes, H.A.

    1983-03-01

    The clouds from seven Pacific Proving Grounds nuclear tests and two Plowshare cratering experiments have been sampled to determine the mass loading of the clouds. The average value for the total mass of debris from surface bursts of megaton yield is 0.2 Mt mass/Mt yield; the measured particle concentration in air ranges from 6 x 10 -10 to 7 x 10 -9 g/cm 3 . The mass of debris per unit yield from cratering explosions is about two orders of magnitude higher than is the case for surface bursts, but only a small percentage of the mass is still present in the cloud after a few minutes. The average concentration of dust in explosion-produced clouds is in the same range as the mass concentration measured in naturally occurring high tropospheric clouds

  15. 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

    lasted for approximately 25 to 30 minutes and was performed at 2-hour intervals from noon to midevening under moderate exercise by 2 individuals. Results: A median ratio of dose rate to background concentration of 0.018 was recorded, with higher ratio values frequently occurring at 12 to 2 PM, the time...

  16. 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…

  17. 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...

  18. 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.

  19. Determination of sediment metal background concentrations and enrichment in marine environments - A critical review.

    Science.gov (United States)

    Birch, G F

    2017-02-15

    'Background' is the concentration of metals in pristine sediment, unaltered by human activity and 'enrichment' is the extent present-day sediment metal concentrations exceed pre-anthropogenic levels (the magnitude of human-induced change). Background and enrichment are becoming more frequently used for management measures to bring sediment and the environment back to near-pristine levels. Of the six empirical methods reviewed for determining background (global values, pristine marine and fluvial sediments, catchment soils and rocks), the use of sedimentary cores has the greatest advantage. Most of the eight statistical methods reviewed are adversely affected by the polymodality and an absence of normality or log-normality, however robust regression procedures are most commonly used. Sorption hypothesis techniques require further development. Indices used to determine enrichment incorporate background levels (enrichment indices) or do not (contamination indices). Of the 20 indices reviewed, the New Nemerow Index and the Mean Enrichment Quotient rate highly in performance, based on 5 beneficial attributes assessed: use of background and normalised data, provision of thresholds, a classification scheme, and inclusion of multiple metals. Variance in background metal concentrations determined in the 43 global projects reviewed is surprisingly moderate, however regional variability may be considerable due to local catchment mineralisation. Chemical analysis of sediment should not include metals bound in the mineral matrix and weak acid extractions are advisable. The use of appropriate and effective indicators of environmental condition are critical to the protection and restoration of marine regions and ensuring that human activities are carried out in a sustainable manner to promote safe, healthy and productive ecosystems. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Indoor and ambient air concentrations of respirable particles between two hospitals in Kashan (2014-2015

    Directory of Open Access Journals (Sweden)

    Mahmoud Mohammadyan

    2017-04-01

    Full Text Available Background: The hospital environment requires special attention to provide healthful indoor air quality for protecting patients and healthcare workers against the occupational diseases. The aim of this study was to determine the concentrations of respirable particles indoor and ambient air of two hospitals in Kashan. Materials and Method: This cross-sectional study was conducted during 3 months (Marth 2014 to May 2015. Indoor and outdoor PM10 and PM2.5 concentrations were measured four times a week in the operating room, pediatric and ICU2 (Intensive Care Unit wards using a real time dust monitor at two hospitals. A total number of 480 samples (80 samples indoors and 40 outdoors from wards were collected. Results: The highest mean PM2.5 and PM10 for indoors were determined 57.61± 68.57 µg m-3 and 212.36±295.49 µg m-3, respectively. The results showed a significant relationship between PM2.5 and PM10 in the indoor and ambient air of two hospitals (P<0.05. PM2.5 and PM10 concentrations were different in all of the selected wards (P<0.05. Conclusion: The respirable particle concentrations in the indoor and ambient air in both hospitals were higher than the 24-hours WHO and US-EPA standards. Thence, utilizing sufficient and efficient air conditioning systems in hospitals can be useful in improving indoor air quality and reducing the respirable particle concentrations.

  1. Secondary particle in background levels and effects on detectors at future hadron colliders

    International Nuclear Information System (INIS)

    Pal, T.

    1993-06-01

    The next generation of hadron colliders, the Superconducting Super Collider (SSC) and the Large Hadron Collider (LHC), will operate at high center-of-mass energies and luminosities. Namely, for the SSC (LHC) √s = 40 TeV (√s = 16 TeV) and L = 10 33 cm -2 s -1 (L = 3 x 10 34 cm -2 s -1 ). These conditions will result in the production of large backgrounds as well as radiation environments. Ascertaining the backgrounds, in terms of the production of secondary charged and neutral particles, and the radiation environments are important considerations for the detectors proposed for these colliders. An initial investigation of the radiation levels in the SSC detectors was undertaken by D. Groom and colleagues, in the context of the ''task force on radiation levels in the SSC interaction regions.'' The method consisted essentially of an analytic approach, using standard descriptions of average events in conjunction with simulations of secondary processes. Following Groom's work, extensive Monte Carlo simulations were performed to address the issues of backgrounds and radiation environments for the GEM and SD C3 experiments proposed at the SSC, and for the ATLAS and CMS experiments planned for the LHC. The purpose of the present article is to give a brief summary of some aspects of the methods, assumptions, and calculations performed to date (principally for the SSC detectors), and to stress the relevance of such calculations to the detectors proposed for the study of B-physics in particular

  2. Chemical Source Localization Fusing Concentration Information in the Presence of Chemical Background Noise.

    Science.gov (United States)

    Pomareda, Víctor; Magrans, Rudys; Jiménez-Soto, Juan M; Martínez, Dani; Tresánchez, Marcel; Burgués, Javier; Palacín, Jordi; Marco, Santiago

    2017-04-20

    We present the estimation of a likelihood map for the location of the source of a chemical plume dispersed under atmospheric turbulence under uniform wind conditions. The main contribution of this work is to extend previous proposals based on Bayesian inference with binary detections to the use of concentration information while at the same time being robust against the presence of background chemical noise. For that, the algorithm builds a background model with robust statistics measurements to assess the posterior probability that a given chemical concentration reading comes from the background or from a source emitting at a distance with a specific release rate. In addition, our algorithm allows multiple mobile gas sensors to be used. Ten realistic simulations and ten real data experiments are used for evaluation purposes. For the simulations, we have supposed that sensors are mounted on cars which do not have among its main tasks navigating toward the source. To collect the real dataset, a special arena with induced wind is built, and an autonomous vehicle equipped with several sensors, including a photo ionization detector (PID) for sensing chemical concentration, is used. Simulation results show that our algorithm, provides a better estimation of the source location even for a low background level that benefits the performance of binary version. The improvement is clear for the synthetic data while for real data the estimation is only slightly better, probably because our exploration arena is not able to provide uniform wind conditions. Finally, an estimation of the computational cost of the algorithmic proposal is presented.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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. (paper)

  4. 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.

  5. A novel robust and efficient algorithm for charge particle tracking in high background flux

    International Nuclear Information System (INIS)

    Fanelli, C; Cisbani, E; Dotto, A Del

    2015-01-01

    The high luminosity that will be reached in the new generation of High Energy Particle and Nuclear physics experiments implies large high background rate and large tracker occupancy, representing therefore a new challenge for particle tracking algorithms. For instance, at Jefferson Laboratory (JLab) (VA,USA), one of the most demanding experiment in this respect, performed with a 12 GeV electron beam, is characterized by a luminosity up to 10 39 cm -2 s -1 . To this scope, Gaseous Electron Multiplier (GEM) based trackers are under development for a new spectrometer that will operate at these high rates in the Hall A of JLab. Within this context, we developed a new tracking algorithm, based on a multistep approach: (i) all hardware - time and charge - information are exploited to minimize the number of hits to associate; (ii) a dedicated Neural Network (NN) has been designed for a fast and efficient association of the hits measured by the GEM detector; (iii) the measurements of the associated hits are further improved in resolution through the application of Kalman filter and Rauch- Tung-Striebel smoother. The algorithm is shortly presented along with a discussion of the promising first results. (paper)

  6. Determination of particle concentration rankings by spatial mapping of particle surface area, number, and mass concentrations in a restaurant and a die casting plant.

    Science.gov (United States)

    Park, Ji Young; Ramachandran, Gurumurthy; Raynor, Peter C; Olson, Gregory M

    2010-08-01

    Measurements using several exposure metrics were carried out in a restaurant and a die casting plant to compare the spatial distributions of particle surface area (SA), number, and mass concentrations and rank exposures in different areas by those metrics. The different exposure metrics for incidental nanoparticle and fine particle exposures were compared using the concentration rankings, statistical differences between areas, and concentration ratios between different areas. In the die casting plant, area concentration rankings and spatial distributions differed by the exposure metrics chosen. Surface area and fine particle number concentrations were greatest near incidental nanoparticle sources and were significantly different between three areas. However, mass and coarse particle number concentrations were similar throughout the facility, and rankings of the work areas based on these metrics were different from those of SA and fine number concentrations. In the restaurant, concentrations in the kitchen for all metrics except respirable mass concentration were significantly greater than in the serving area, although SA and fine particle number concentrations showed larger differences between the two areas than either the mass or coarse particle number concentrations. Thus, the choice of appropriate exposure metric has significant implications for exposure groupings in epidemiologic and occupational exposure studies.

  7. Upgrade of the DAUMOD atmospheric dispersion model to estimate urban background NO2 concentrations

    Science.gov (United States)

    Pineda Rojas, Andrea L.; Venegas, Laura E.

    2013-02-01

    Ambient concentrations of nitrogen dioxide (NO2) resulting from the emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) in an urban area may cause adverse impacts on the human health and the natural environment if they exceed the air quality standards. The evaluation of NO2 can be achieved through the application of air quality models including photochemical reactions. DAUMOD is a simple urban scale atmospheric dispersion model which was originally developed to estimate urban background concentrations of inert species. In order to allow the estimation of NO2 concentrations in an urban atmosphere, the DAUMOD model has been recently coupled to the Generic Reaction Set (GRS), a simplified photochemical scheme. This work presents the development of the DAUMOD-GRS model and its first application in the city of Buenos Aires considering high resolution area source NOx and VOC emissions recently obtained for the area. Estimated hourly NO2 concentrations are compared with the observations from a campaign carried out at a green open area within the city in winter 2001. Results show a good model performance, with NMSE = 0.49, FA2 = 0.676 and FB = - 0.097. DAUMOD-GRS is applied to obtain the spatial distribution of annual NO2 concentrations in the city. The maximum value is 36 ppb, indicating that annual NO2 concentrations in Buenos Aires are below the Air Quality Standard (53 ppb). In addition, hourly ozone concentrations estimated by DAUMOD-GRS are compared with observed values, giving NMSE = 0.38, FA2 = 0.684 and FB = - 0.225.

  8. Secondary particle background levels and effects on detectors at future hadron colliders

    International Nuclear Information System (INIS)

    Pal, T.

    1993-01-01

    The next generation of hadron colliders, the Superconducting Super Collider (SSC) and the Large Hadron Collider (LHC), will operate at high center-of-mass energies and luminosities. Namely, for the SSC(LHC) √s=40TeV (√s=16TeV) and L=10 33 cm -2 s -1 (L=3x10 34 cm -2 s -1 ). These conditions will result in the production of large backgrounds as well as radiation environments. Ascertaining the backgrounds, in terms of the production of secondary charged and neutral particles, and the radiation environments are important considerations for the detectors proposed for these colliders. An initial investigation of the radiation levels in the SSC detectors was undertaken by D. Groom and colleagues, in the context of the open-quotes task force on radiation levels in the SSC interaction regions.close quotes The method consisted essentially of an analytic approach, using standard descriptions of average events in conjunction with simulations of secondary processes

  9. Impact of roadside noise barriers on particle size distributions and pollutants concentrations near freeways

    Science.gov (United States)

    Ning, Zhi; Hudda, Neelakshi; Daher, Nancy; Kam, Winnie; Herner, Jorn; Kozawa, Kathleen; Mara, Steven; Sioutas, Constantinos

    2010-08-01

    Increasing epidemiological evidence has established an association between a host of adverse health effects and exposure to ambient particulate matter (PM) and co-pollutants, especially those emitted from motor vehicles. Although PM and their co-pollutants dispersion profiles near the open freeway have been extensively characterized by means of both experimental measurements and numerical simulations in recent years, such investigations near freeways with roadside barriers have not been well documented in the literature. A few previous studies suggested that the presence of roadside structures, such as noise barriers and vegetation, may impact the decay of pollutant concentrations downwind of the freeway by limiting the initial dispersion of traffic emissions and increasing their vertical mixing due to the upward deflection of airflow. Since the noise barriers are now common roadside features of the freeways, particularly those running through populated urban areas, it is pertinent to investigate the impact of their presence on the particles and co-pollutants concentrations in areas adjacent to busy roadways. This study investigated two highly trafficked freeways (I-710 and I-5) in Southern California, with two sampling sites for each freeway, one with and the other without the roadside noise barriers. Particle size distributions and co-pollutants concentrations were measured in the immediate proximity of freeways and at different distances downwind of the freeways. The results showed the formation of a "concentration deficit" zone in the immediate vicinity of the freeway with the presence of roadside noise barrier, followed by a surge of pollutant concentrations further downwind at 80-100 m away from freeway. The particle and co-pollutants concentrations reach background levels at farther distances of 250-400 m compared to 150-200 m at the sites without roadside noise barriers.

  10. Long-term cloud condensation nuclei number concentration, particle number size distribution and chemical composition measurements at regionally representative observatories

    Science.gov (United States)

    Schmale, Julia; Henning, Silvia; Decesari, Stefano; Henzing, Bas; Keskinen, Helmi; Sellegri, Karine; Ovadnevaite, Jurgita; Pöhlker, Mira L.; Brito, Joel; Bougiatioti, Aikaterini; Kristensson, Adam; Kalivitis, Nikos; Stavroulas, Iasonas; Carbone, Samara; Jefferson, Anne; Park, Minsu; Schlag, Patrick; Iwamoto, Yoko; Aalto, Pasi; Äijälä, Mikko; Bukowiecki, Nicolas; Ehn, Mikael; Frank, Göran; Fröhlich, Roman; Frumau, Arnoud; Herrmann, Erik; Herrmann, Hartmut; Holzinger, Rupert; Kos, Gerard; Kulmala, Markku; Mihalopoulos, Nikolaos; Nenes, Athanasios; O'Dowd, Colin; Petäjä, Tuukka; Picard, David; Pöhlker, Christopher; Pöschl, Ulrich; Poulain, Laurent; Prévôt, André Stephan Henry; Swietlicki, Erik; Andreae, Meinrat O.; Artaxo, Paulo; Wiedensohler, Alfred; Ogren, John; Matsuki, Atsushi; Yum, Seong Soo; Stratmann, Frank; Baltensperger, Urs; Gysel, Martin

    2018-02-01

    Aerosol-cloud interactions (ACI) constitute the single largest uncertainty in anthropogenic radiative forcing. To reduce the uncertainties and gain more confidence in the simulation of ACI, models need to be evaluated against observations, in particular against measurements of cloud condensation nuclei (CCN). Here we present a data set - ready to be used for model validation - of long-term observations of CCN number concentrations, particle number size distributions and chemical composition from 12 sites on 3 continents. Studied environments include coastal background, rural background, alpine sites, remote forests and an urban surrounding. Expectedly, CCN characteristics are highly variable across site categories. However, they also vary within them, most strongly in the coastal background group, where CCN number concentrations can vary by up to a factor of 30 within one season. In terms of particle activation behaviour, most continental stations exhibit very similar activation ratios (relative to particles > 20 nm) across the range of 0.1 to 1.0 % supersaturation. At the coastal sites the transition from particles being CCN inactive to becoming CCN active occurs over a wider range of the supersaturation spectrum. Several stations show strong seasonal cycles of CCN number concentrations and particle number size distributions, e.g. at Barrow (Arctic haze in spring), at the alpine stations (stronger influence of polluted boundary layer air masses in summer), the rain forest (wet and dry season) or Finokalia (wildfire influence in autumn). The rural background and urban sites exhibit relatively little variability throughout the year, while short-term variability can be high especially at the urban site. The average hygroscopicity parameter, κ, calculated from the chemical composition of submicron particles was highest at the coastal site of Mace Head (0.6) and lowest at the rain forest station ATTO (0.2-0.3). We performed closure studies based on κ-Köhler theory

  11. Gravitational settling of a highly concentrated system of solid spherical particles

    Science.gov (United States)

    Arkhipov, V. A.; Usanina, A. S.

    2017-09-01

    In the present paper, we report on the results of an experimental study of the process of gravity sedimentation of a cloud of monodispersed solid spherical particles with initial volume concentration C > 0.03, which was performed in a wide range of Reynolds numbers. An analytical estimate of the settling regimes of spherical particle clouds is presented. A new method for creating a spherical particle cloud with a high concentration of particles is proposed. A qualitative picture of the settling process of a highly concentrated particle cloud under gravity is revealed. A criterial dependence for the drag coefficient of a sedimenting spherical particle cloud as an entity is obtained.

  12. Flow behaviour and local concentration of coarse particles-water mixture in inclined pipes

    Directory of Open Access Journals (Sweden)

    Vlasak Pavel

    2017-06-01

    Full Text Available Narrow particle size distribution basalt pebbles of mean particle size 11.5 mm conveyed by water in the pipe sections of different inclination were investigated on an experimental pipe loop, consisting of smooth stainless steel pipes of inner diameter D = 100 mm. Mixture flow-behaviour and particles motion along the pipe invert were studied in a pipe viewing section, the concentration distribution in pipe cross-section was studied with the application of a gamma-ray densitometer. The study refers to the effect of mixture velocity, overall concentration, and angle of pipe inclination on chord-averaged concentration profiles and local concentration maps, and flow behaviour of the coarse particle-water mixtures. The study revealed that the coarse particle-water mixtures in the inclined pipe sections were significantly stratified, the solid particles moved principally close to the pipe invert, and for higher and moderate flow velocities particle saltation becomes the dominant mode of particle conveying.

  13. Concentration of 210Po in local foodstuffs grown nearby High Background Areas (HBRA)

    International Nuclear Information System (INIS)

    Kamesh Viswanathan, B.; Arunachalam, Kantha D.; Sathesh Kumar, A.; Jayakrishna, K.; Rao, D.D.

    2012-01-01

    210 Po is the decay product of natural radionuclide of 238 U series. The presence of a radionuclide migrates from soil > plant > food and ingested by the humans residing in the areas of syentite rocks nearby the High Background Radiation Area's (HBRA). The food samples were studied by Market Basket Study (MBS). The average concentration of 210 Po in foodstuffs like green leafy vegetables, other vegetables, roots and tubers; fruits, fish, other flesh foods, milk and cereals were 1671 ± 163.3, 28.2 ± 7.3, 320 ± 99, 53 ± 17.5, 251.5 ± 54.5, 37 ± 14.5, 16 ± 6 and 230 ± 75 mBq. Kg -1 fresh weight. (author)

  14. High pulse number thermal shock tests on tungsten with steady state particle background

    Science.gov (United States)

    Wirtz, M.; Kreter, A.; Linke, J.; Loewenhoff, Th; Pintsuk, G.; Sergienko, G.; Steudel, I.; Unterberg, B.; Wessel, E.

    2017-12-01

    Thermal fatigue of metallic materials, which will be exposed to severe environmental conditions e.g. plasma facing materials in future fusion reactors, is an important issue in order to predict the life time of complete wall components. Therefore experiments in the linear plasma device PSI-2 were performed to investigate the synergistic effects of high pulse number thermal shock events (L = 0.38 GW m‑2, Δt = 0.5 ms) and stationary D/He (6%) plasma particle background on the thermal fatigue behavior of tungsten. Similar to experiments with pure thermal loads, the induced microstructural and surface modifications such as recrystallization and roughening as well as crack formation become more pronounced with increasing number of thermal shock events. However, the amount of damage significantly increases for synergistic loads showing severe surface roughening, plastic deformation and erosion resulting from the degradation of the mechanical properties caused by bombardment and diffusion of D/He to the surface and the bulk of the material. Additionally, D/He induced blistering and bubble formation were observed for all tested samples, which could change the thermal and mechanical properties of near surface regions.

  15. Calculating exclusion limits for weakly interacting massive particle direct detection experiments without background subtraction

    International Nuclear Information System (INIS)

    Green, Anne M.

    2002-01-01

    Competitive limits on the weakly interacting massive particle (WIMP) spin-independent scattering cross section are currently being produced by 76 Ge detectors originally designed to search for neutrinoless double beta decay, such as the Heidelberg-Moscow and IGEX experiments. In the absence of background subtraction, limits on the WIMP interaction cross section are set by calculating the upper confidence limit on the theoretical event rate, given the observed event rate. The standard analysis technique involves calculating the 90% upper confidence limit on the number of events in each bin, and excluding any set of parameters (WIMP mass and cross section) which produces a theoretical event rate for any bin which exceeds the 90% upper confidence limit on the event rate for that bin. We show that, if there is more than one energy bin, this produces exclusion limits that are actually at a lower degree of confidence than 90%, and are hence erroneously tight. We formulate criteria which produce true 90% confidence exclusion limits in these circumstances, including calculating the individual bin confidence limit for which the overall probability that no bins exceed this confidence limit is 90% and calculating the 90% minimum confidence limit on the number of bins which exceed their individual bin 90% confidence limits. We then compare the limits on the WIMP cross section produced by these criteria with those found using the standard technique, using data from the Heidelberg-Moscow and IGEX experiments

  16. Soil-Air exchange controls on background atmospheric concentrations of organochlorine pesticides

    Science.gov (United States)

    Cabrerizo, A.; Dachs, J.; Jones, K. C.; Barceló, D.

    2011-12-01

    Soils are the major terrestrial reservoir of persistent organic pollutants, and thus net volatilization from soil, when it happens, may exert a control on the atmospheric occurrence and variability of organic pollutants. Here, we report and discuss the concentrations of legacy organochlorine pesticides (OCPs) such as hexachlorobenzene (HCB), hexaclorocyclohexanes (HCH) and dichlorodiphenyltrichloroethane (DDT) in the atmosphere and in soils, their measured fugacities in soil, the soil-air partition coefficients (KSA) and soil-air fugacity ratios (fs/fa) in rural background areas of N-NE Spain and N-NW England. Four sampling campaigns were carried out in Spain and UK to assess seasonal variability and differences between sampling sites. KSA values were significantly dependent on soil temperature and soil organic matter quantity, and to a minor extent on organic matter type. HCH isomers and DDT metabolites in soil are close to equilibrium with the overlying atmosphere at rural background areas of Spain with a tendency to volatilize and deposit during warm and cold periods, respectively. The mixture of HCH and DDT found in the atmosphere is clearly strongly influenced by the mixture of HCH and DDT which escapes from soil, with significant correlations between them (r2 ranging between 0.63-0.76 and p-level<0.001 for the Ebro sampling sites), thus suggesting a close coupling of air and soil concentrations, demonstrating that net volatilization from soil control the atmospheric levels of OCPs in the Northern Spain background atmosphere. Conversely, soils at rural UK sites were usually a sink for atmospheric DDT and HCH, but not for HCB. The negative statistically significant relationship found between log KSA and the log (fs/fa) ratio, suggests that high latitude regions, due to the high soil organic matter content and lower temperatures, will act as larger traps and accumulate more atmospheric OCPs. Thus, the extent to which soils are secondary sources to the atmosphere

  17. Soil-Air exchange controls on background atmospheric concentrations of organochlorine pesticides

    Directory of Open Access Journals (Sweden)

    A. Cabrerizo

    2011-12-01

    Full Text Available Soils are the major terrestrial reservoir of persistent organic pollutants, and thus net volatilization from soil, when it happens, may exert a control on the atmospheric occurrence and variability of organic pollutants. Here, we report and discuss the concentrations of legacy organochlorine pesticides (OCPs such as hexachlorobenzene (HCB, hexaclorocyclohexanes (HCH and dichlorodiphenyltrichloroethane (DDT in the atmosphere and in soils, their measured fugacities in soil, the soil-air partition coefficients (KSA and soil-air fugacity ratios (fs/fa in rural background areas of N-NE Spain and N-NW England. Four sampling campaigns were carried out in Spain and UK to assess seasonal variability and differences between sampling sites. KSA values were significantly dependent on soil temperature and soil organic matter quantity, and to a minor extent on organic matter type. HCH isomers and DDT metabolites in soil are close to equilibrium with the overlying atmosphere at rural background areas of Spain with a tendency to volatilize and deposit during warm and cold periods, respectively. The mixture of HCH and DDT found in the atmosphere is clearly strongly influenced by the mixture of HCH and DDT which escapes from soil, with significant correlations between them (r2 ranging between 0.63–0.76 and p-level<0.001 for the Ebro sampling sites, thus suggesting a close coupling of air and soil concentrations, demonstrating that net volatilization from soil control the atmospheric levels of OCPs in the Northern Spain background atmosphere. Conversely, soils at rural UK sites were usually a sink for atmospheric DDT and HCH, but not for HCB. The negative statistically significant relationship found between log KSA and the log (fs/fa ratio, suggests that high latitude regions, due to the high soil organic matter content

  18. 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.

  19. A constitutive equation for concentrated suspensions that accounts for shear-induced particle migration

    International Nuclear Information System (INIS)

    Phillips, R.J.; Armstrong, R.C.; Brown, R.A.; Graham, A.L.; Abbott, J.R.

    1992-01-01

    A constitutive equation for computing particle concentration and velocity fields in concentrated monomodal suspensions is proposed that consists of two parts: a Newtonian constitutive equation in which the viscosity depends on the local particle volume fraction and a diffusion equation that accounts for shear-induced particle migration. Particle flux expressions used to obtain the diffusion equation are derived by simple scaling arguments. Predictions are made for the particle volume fraction and velocity fields for steady Couette and Poiseuille flow, and for transient start-up of steady shear flow in a Couette apparatus. Particle concentrations for a monomodal suspension of polymethyl methacrylate spheres in a Newtonian solvent are measured by nuclear magnetic resonance (NMR) imaging in the Couette geometry for two particle sizes and volume fractions. The predictions agree remarkably well with the measurements for both transient and steady-state experiments as well as for different particle sizes

  20. Size distribution and total number concentration of ultrafine and accumulation mode particles and hospital admissions in children and the elderly in Copenhagen, Denmark

    DEFF Research Database (Denmark)

    Andersen, Zorana Jovanovic; Wåhlin, Peter; Raaschou-Nielsen, O

    2008-01-01

    OBJECTIVES: To study the association between short-term exposure to ultrafine particles and morbidity in Copenhagen, Denmark. METHODS: We studied the association between urban background levels of the total number concentration of particles (NC(tot), 6-700 nm in diameter) measured at a single sit...

  1. 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. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Source apportionment of ambient particle number concentrations in central Los Angeles using positive matrix factorization (PMF)

    Science.gov (United States)

    Sowlat, Mohammad Hossein; Hasheminassab, Sina; Sioutas, Constantinos

    2016-04-01

    In this study, the positive matrix factorization (PMF) receptor model (version 5.0) was used to identify and quantify major sources contributing to particulate matter (PM) number concentrations, using PM number size distributions in the range of 13 nm to 10 µm combined with several auxiliary variables, including black carbon (BC), elemental and organic carbon (EC/OC), PM mass concentrations, gaseous pollutants, meteorological, and traffic counts data, collected for about 9 months between August 2014 and 2015 in central Los Angeles, CA. Several parameters, including particle number and volume size distribution profiles, profiles of auxiliary variables, contributions of different factors in different seasons to the total number concentrations, diurnal variations of each of the resolved factors in the cold and warm phases, weekday/weekend analysis for each of the resolved factors, and correlation between auxiliary variables and the relative contribution of each of the resolved factors, were used to identify PM sources. A six-factor solution was identified as the optimum for the aforementioned input data. The resolved factors comprised nucleation, traffic 1, traffic 2 (with a larger mode diameter than traffic 1 factor), urban background aerosol, secondary aerosol, and soil/road dust. Traffic sources (1 and 2) were the major contributor to PM number concentrations, collectively making up to above 60 % (60.8-68.4 %) of the total number concentrations during the study period. Their contribution was also significantly higher in the cold phase compared to the warm phase. Nucleation was another major factor significantly contributing to the total number concentrations (an overall contribution of 17 %, ranging from 11.7 to 24 %), with a larger contribution during the warm phase than in the cold phase. The other identified factors were urban background aerosol, secondary aerosol, and soil/road dust, with relative contributions of approximately 12 % (7.4-17.1), 2.1 % (1

  3. Effects of types of ventilation system on indoor particle concentrations in residential buildings.

    Science.gov (United States)

    Park, J S; Jee, N-Y; Jeong, J-W

    2014-12-01

    The objective of this study was to quantify the influence of ventilation systems on indoor particle concentrations in residential buildings. Fifteen occupied, single-family apartments were selected from three sites. The three sites have three different ventilation systems: unbalanced mechanical ventilation, balanced mechanical ventilation, and natural ventilation. Field measurements were conducted between April and June 2012, when outdoor air temperatures were comfortable. Number concentrations of particles, PM2.5 and CO2 , were continuously measured both outdoors and indoors. In the apartments with natural ventilation, I/O ratios of particle number concentrations ranged from 0.56 to 0.72 for submicron particles, and from 0.25 to 0.60 for particles larger than 1.0 μm. The daily average indoor particle concentration decreased to 50% below the outdoor level for submicron particles and 25% below the outdoor level for fine particles, when the apartments were mechanically ventilated. The two mechanical ventilation systems reduced the I/O ratios by 26% for submicron particles and 65% for fine particles compared with the natural ventilation. These results showed that mechanical ventilation can reduce exposure to outdoor particles in residential buildings. Results of this study confirm that mechanical ventilation with filtration can significantly reduce indoor particle levels compared with natural ventilation. The I/O ratios of particles substantially varied at the naturally ventilated apartments because of the influence of variable window opening conditions and unsteadiness of wind flow on the penetration of outdoor air particles. For better prediction of the exposure to outdoor particles in naturally ventilated residential buildings, it is important to understand the penetration of outdoor particles with variable window opening conditions. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. 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

  5. Illustration of a fingerprinting method to isolate Gold King Release Metals from Background Concentrations in the San Juan River

    Science.gov (United States)

    Detecting the Gold King Mine metals as the release plume passed was difficult once it entered the San Juan River on August 8, 2015. Plume metals concentrations were relatively low after 200 km of travel and deposition in the Animas River while background concentrations of the sa...

  6. Effect of surfactant concentration to aggregations of nanogold particles

    Science.gov (United States)

    Duangthanu, Methawee; Pattanaporkratana, Apichart

    2017-09-01

    This research presents a study of aggregation of colloidal gold nanoparticles using 400 nm diameter gold nanoparticles mixed with a surfactant (Plantacare 2000) at various concentrations. When observed under a microscope, we found that the nanoparticles aggregated to form nearly spherical clusters at the beginning of the formation, and then sedimented to the bottom of the container. These clusters moved with Brownian’s motion and collided with each other in the horizontal plane, forming branch-like clusters in 2D. The appearance and size of the clusters were different depending on the concentration of surfactant. The clusters’ size and appearance were rarely changed after mixing with surfactant for 90 minutes, and we found that the cluster’s shapes were nearly spherical at low surfactant concentration (c = 0.25%). At surfactant concentration between 0.50% - 5.00%, the aggregates formed branch-like clusters with skinnier branches and smaller sizes at higher surfactant concentration. Moreover, we also found that, at surfactant concentrations between 2.50% - 5.00%, nanoparticles and aggregates stuck to the bottom of the glass container quickly and rarely moved after 10 minutes. At c = 0.25%, the 2D fractal dimension of the aggregates was measured to be D = 1.88 ± 0.04, since the aggregates were nearly spherical. The fractal dimension decreased to the minimum of D = 1.50 ± 0.12 at c = 1.50%, similar to D ∼ 1.45 found in diffusion-limited cluster aggregation (DLCA). At surfactant concentration above 1.50%, the fractal dimension increased until it reached the value of D ∼ 1.66 at c = 5.00%.

  7. Evolution of Size and Chemical Composition of Copper Concentrate Particles Oxidized Under Simulated Flash Smelting Conditions

    Science.gov (United States)

    Pérez-Tello, Manuel; Parra-Sánchez, Víctor R.; Sánchez-Corrales, Víctor M.; Gómez-Álvarez, Agustín; Brown-Bojórquez, Francisco; Parra-Figueroa, Roberto A.; Balladares-Varela, Eduardo R.; Araneda-Hernández, Eugenia A.

    2018-01-01

    An experimental study was conducted to elucidate the evolution of size and chemical composition of La Caridad copper concentrate particles during oxidation under simulated flash smelting conditions. Input variables tested included particle size and oxygen concentration in the process gas. The response variables included the size distributions, chemical composition, and morphology of the reacted particles at seven locations along a laboratory reactor. Particles with initial size 45 µm contained varying amounts of chalcopyrite and pyrite, and tended to either maintain or decrease their mean size upon oxidation. When size reduction was observed, dust was produced because of fragmentation, and the particles showed no evidence of collisions during flight. The main oxidation products detected in the particles consisted of matte, cuprospinel, and magnetite. A plot of the mean size divided by the mean size in the feed against the fraction of sulfur eliminated generalized the experimental data so far reported in the literature, and helped identify the reaction path followed by the particles.

  8. 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...... application to images of heterogeneous catalysts is presented....

  9. Correlation of Air Quality Data to Ultrafine Particles (UFP Concentration and Size Distribution in Ambient Air

    Directory of Open Access Journals (Sweden)

    Werner Hofmann

    2010-07-01

    Full Text Available This study monitored ultrafine particles (UFP concurrent with environmental air quality data, investigating whether already existing instrumentation used by environmental authorities can provide reference values for estimating UFP concentrations. Of particular interest was the relation of UFP to PM10 (particulate matter and nitrogen oxides (NOx, NO2 in ambient air. Existing PM measurement methods alone did not correspond exactly enough with the actual particle number, but we observed a link between NOx and NO2 to UFP concentration. The combined data could act as proxy-indicator for authorities in estimating particle number concentrations, but cannot replace UFP monitoring.

  10. 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

    % of the mass of airborne particulate tire debris have aerodynamic diameters smaller than 1 mum. The mean aerodynamic diameter is about I gm for the bitumen particles. This size range enables the possibility for far range transport and inhalation by humans. Soil concentrations in the vicinity of a highway...... indicate an approximate exponential decrease with increasing distance from the road. Constant values are reached after about 5 m for the tire particles and 10 m for the bitumen particles. Concentrations in soil that has not been touched for at least 30 years show a decrease in tire concentration...

  11. Particle currents in a space-time dependent and CP-violating Higgs background: a field theory approach

    International Nuclear Information System (INIS)

    Comelli, D.; Riotto, A.

    1995-06-01

    Motivated by cosmological applications like electroweak baryogenesis, we develop a field theoretic approach to the computation of particle currents on a space-time dependent and CP-violating Higgs background. We consider the Standard Model model with two Higgs doublets and CP violation in the scalar sector, and compute both fermionic and Higgs currents by means of an expansion in the background fields. We discuss the gauge dependence of the results and the renormalization of the current operators, showing that in the limit of local equilibrium, no extra renormalization conditions are needed in order to specify the system completely. (orig.)

  12. Trace anomaly of the stress-energy tensor for massless vector particles propagating in a general background metric

    International Nuclear Information System (INIS)

    Adler, S.L.; Lieberman, J.

    1978-01-01

    We reanalyze the problem of regularization of the stress-energy tensor for massless vector particles propating in a general background metric, using covariant point separation techniques applied to the Hadamard elementary solution. We correct an error, point out by Wald, in the earlier formulation of Adler, Lieberman, and Ng, and find a stress-energy tensor trace anomaly agreeing with that found by other regularization methods

  13. Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis

    OpenAIRE

    Niemi , J. V.; Saarikoski , S.; Tervahattu , H.; Mäkelä , T.; Hillamo , R.; Vehkamäki , H.; Sogacheva , L.; Kulmala , M.

    2006-01-01

    Aerosol samples were collected at a rural background site in southern Finland in May 2004 during pollution episode (PM1~16 µg m−3, backward air mass trajectories from south-east), intermediate period (PM1~5 µg m−3, backtrajectories from north-east) and clean period (PM1~2 µg m−3, backtrajectories from north-west/north). The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were st...

  14. Number concentrations of solid particles from the spinning top aerosol generator

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, J.P.

    1983-02-01

    A spinning top aerosol generator has been used to generate monodisperse methylene blue particles in the size range from 0.6 to 6 ..mu..m. The number concentrations of these aerosols have been determined by means of an optical particle counter and compared with the equivalent measurements obtained by filter collection and microscopy.

  15. Brittle-tough transition in nylon-rubber blends: effect of rubber concentration and particle size

    NARCIS (Netherlands)

    Borggreve, R.J.M.; Gaymans, R.J.; Schuijer, J.; Ingen Housz, J.F.

    1987-01-01

    Blends of nylon-6 and EPDM-rubber were prepared with various rubber contents (0–20 wt%) and particle sizes (0.3–1.6 μm). The effects of rubber concentration and particle size on the tensile modulus, torsion modulus, yield stress and notched impact strength of the blends were studied. Blend

  16. Source apportionment of urban fine particle number concentration during summertime in Beijing

    Science.gov (United States)

    Liu, Z. R.; Hu, B.; Liu, Q.; Sun, Y.; Wang, Y. S.

    2014-10-01

    Continuous particle number size distributions (15 nm-2.5 μm), particle chemical compositions, gaseous species and meteorological variables were collected at an urban site in Beijing to investigate the source apportionment of ambient fine particle number concentrations. Hourly data sets were analyzed using the positive matrix factorisation (PMF) which identified a total of eight factors: two traffic factors, two combustion factors, secondary nitrate factors, secondary sulfate + secondary organic aerosol (SOA), fugitive dust and regionally transported aerosol. Traffic (47.9%) and combustion (29.7%) aerosol were found to dominate the particle number concentrations, whereas the most important sources for particle volume concentrations were found to be regionally transported aerosol (30.9%) and combustions (30.1%). Although the diurnal pattern of each of the two traffic factors closely followed traffic rush hour for Beijing, their size modes were different suggesting that these factors might represent local and remote emissions. Biomass burning and coal-fired power plant aerosol were distinguished according to their size modes and chemical species associated with them. Secondary compounds showed similar bimodal particle number size distribution, the distinct diurnal pattern distinguished these factors as secondary nitrate and mixed source of secondary sulfate and SOA. Regionally transported material was characterized by accumulation mode particles. Overall, the introduction of combinations of particle number size distributions and chemical composition data in PMF model is successful at separating the components and quantifying relative contributions to the particle number and volume size distributions in the complex urban atmosphere.

  17. 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.)

  18. Nitro-polycyclic aromatic hydrocarbons - gas-particle partitioning, mass size distribution, and formation along transport in marine and continental background air

    Science.gov (United States)

    Lammel, Gerhard; Mulder, Marie D.; Shahpoury, Pourya; Kukučka, Petr; Lišková, Hana; Přibylová, Petra; Prokeš, Roman; Wotawa, Gerhard

    2017-05-01

    Nitro-polycyclic aromatic hydrocarbons (NPAH) are ubiquitous in polluted air but little is known about their abundance in background air. NPAHs were studied at one marine and one continental background site, i.e. a coastal site in the southern Aegean Sea (summer 2012) and a site in the central Great Hungarian Plain (summer 2013), together with the parent compounds, PAHs. A Lagrangian particle dispersion model was used to track air mass history. Based on Lagrangian particle statistics, the urban influence on samples was quantified for the first time as a fractional dose to which the collected volume of air had been exposed. At the remote marine site, the 3-4-ring NPAH (sum of 11 targeted species) concentration was 23.7 pg m-3 while the concentration of 4-ring PAHs (6 species) was 426 pg m-3. The most abundant NPAHs were 2-nitrofluoranthene (2NFLT) and 3-nitrophenanthrene. Urban fractional doses in the range of Day-night variation of NPAHs at the continental site reflected shorter lifetime during the day, possibly because of photolysis of some NPAHs. The yields of formation of 2NFLT and 2-nitropyrene (2NPYR) in marine air seem to be close to the yields for OH-initiated photochemistry observed in laboratory experiments under high NOx conditions. Good agreement is found for the prediction of NPAH gas-particle partitioning using a multi-phase poly-parameter linear free-energy relationship. Sorption to soot is found to be less significant for gas-particle partitioning of NPAHs than for PAHs. The NPAH levels determined in the south-eastern outflow of Europe confirm intercontinental transport potential.

  19. 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...

  20. Trends in black carbon and size-resolved particle number concentrations and vehicle emission factors under real-world conditions

    Science.gov (United States)

    Krecl, Patricia; Johansson, Christer; Targino, Admir Créso; Ström, Johan; Burman, Lars

    2017-09-01

    Kerbside concentrations of NOx, black carbon (BC), total number of particles (diameter > 4 nm) and number size distribution (28-410 nm) were measured at a busy street canyon in Stockholm in 2006 and 2013. Over this period, there was an important change in the vehicle fleet due to a strong dieselisation process of light-duty vehicles and technological improvement of vehicle engines. This study assesses the impact of these changes on ambient concentrations and particle emission factors (EF). EF were calculated by using a novel approach which combines the NOx tracer method with positive matrix factorisation (PMF) applied to particle number size distributions. NOx concentrations remained rather constant between these two years, whereas a large decrease in particle concentrations was observed, being on average 60% for BC, 50% for total particle number, and 53% for particles in the range 28-100 nm. The PMF analysis yielded three factors that were identified as contributions from gasoline vehicles, diesel fleet, and urban background. This separation allowed the calculation of the average vehicle EF for each particle metric per fuel type. In general, gasoline EF were lower than diesel EF, and EF for 2013 were lower than the ones derived for 2006. The EFBC decreased 77% for both gasoline and diesel fleets, whereas the particle number EF reduction was higher for the gasoline (79%) than for the diesel (37%) fleet. Our EF are consistent with results from other on-road studies, which reinforces that the proposed methodology is suitable for EF determination and to assess the effectiveness of policies implemented to reduce vehicle exhaust emissions. However, our EF are much higher than EF simulated with traffic emission models (HBEFA and COPERT) that are based on dynamometer measurements, except for EFBC for diesel vehicles. This finding suggests that the EF from the two leading models in Europe should be revised for BC (gasoline vehicles) and particle number (all vehicles

  1. Design of Particle-Based Thermal Energy Storage for a Concentrating Solar Power System

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhiwen [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zhang, Ruichong [Colorado School of Mines; Sawaged, Fadi [Colorado School of Mines

    2017-06-03

    Solid particles can operate at higher temperature than current molten salt or oil, and they can be a heat-transfer and storage medium in a concentrating solar power (CSP) system. By using inexpensive solid particles and containment material for thermal energy storage (TES), the particle-TES cost can be significantly lower than other TES methods such as a nitrate-salt system. The particle-TES system can hold hot particles at more than 800 degrees C with high thermal performance. The high particle temperatures increase the temperature difference between the hot and cold particles, and they improve the TES capacity. The particle-based CSP system is able to support high-efficiency power generation, such as the supercritical carbon-dioxide Brayton power cycle, to achieve >50% thermal-electric conversion efficiency. This paper describes a solid particle-TES system that integrates into a CSP plant. The hot particles discharge to a heat exchanger to drive the power cycle. The returning cold particles circulate through a particle receiver to absorb solar heat and charge the TES. This paper shows the design of a particle-TES system including containment silos, foundation, silo insulation, and particle materials. The analysis provides results for four TES capacities and two silo configurations. The design analysis indicates that the system can achieve high thermal efficiency, storage effectiveness (i.e., percentage usage of the hot particles), and exergetic efficiency. An insulation method for the hot silo was considered. The particle-TES system can achieve high performance and low cost, and it holds potential for next-generation CSP technology.

  2. Long-term cloud condensation nuclei number concentration, particle number size distribution and chemical composition measurements at regionally representative observatories

    Directory of Open Access Journals (Sweden)

    J. Schmale

    2018-02-01

    Full Text Available Aerosol–cloud interactions (ACI constitute the single largest uncertainty in anthropogenic radiative forcing. To reduce the uncertainties and gain more confidence in the simulation of ACI, models need to be evaluated against observations, in particular against measurements of cloud condensation nuclei (CCN. Here we present a data set – ready to be used for model validation – of long-term observations of CCN number concentrations, particle number size distributions and chemical composition from 12 sites on 3 continents. Studied environments include coastal background, rural background, alpine sites, remote forests and an urban surrounding. Expectedly, CCN characteristics are highly variable across site categories. However, they also vary within them, most strongly in the coastal background group, where CCN number concentrations can vary by up to a factor of 30 within one season. In terms of particle activation behaviour, most continental stations exhibit very similar activation ratios (relative to particles  > 20 nm across the range of 0.1 to 1.0 % supersaturation. At the coastal sites the transition from particles being CCN inactive to becoming CCN active occurs over a wider range of the supersaturation spectrum. Several stations show strong seasonal cycles of CCN number concentrations and particle number size distributions, e.g. at Barrow (Arctic haze in spring, at the alpine stations (stronger influence of polluted boundary layer air masses in summer, the rain forest (wet and dry season or Finokalia (wildfire influence in autumn. The rural background and urban sites exhibit relatively little variability throughout the year, while short-term variability can be high especially at the urban site. The average hygroscopicity parameter, κ, calculated from the chemical composition of submicron particles was highest at the coastal site of Mace Head (0.6 and lowest at the rain forest station ATTO (0.2–0.3. We performed closure

  3. 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.

  4. Prediction of Particle Concentration using Traffic Emission Model

    Science.gov (United States)

    He, Hong-di; Lu, Jane Wei-zhen

    2010-05-01

    Vehicle emission is regarded as one of major sources of air pollution in urban area. Much attention has been addressed on it especially at traffic intersection. At intersection, vehicles frequently stop with idling engine during the red time and speed-up rapidly in the green time, which result in a high velocity fluctuation and produce extra pollutants to the surrounding air. To deeply understand such process, a semi-empirical model for predicting the changing effect of traffic flow patterns on particulate concentrations is proposed. The performance of the model is evaluated using the correlation coefficient and other parameters. From the results, the correlation coefficients in morning and afternoon data were found to be 0.86 an 0.73 respectively, which implies that the semi-empirical model for morning and afternoon data are 86% and 73% error free. Due to less affected by possible factors such as traffic volume and movement of pedestrian, the dispersion of the particulate matter in the morning is smaller and then contributes to higher performance than that in the afternoon.

  5. Analysis of local-scale background concentrations of methane and other gas-phase species in the Marcellus Shale

    Directory of Open Access Journals (Sweden)

    J. Douglas Goetz

    2017-02-01

    Full Text Available The Marcellus Shale is a rapidly developing unconventional natural gas resource found in part of the Appalachian region. Air quality and climate concerns have been raised regarding development of unconventional natural gas resources. Two ground-based mobile measurement campaigns were conducted to assess the impact of Marcellus Shale natural gas development on local scale atmospheric background concentrations of air pollution and climate relevant pollutants in Pennsylvania. The first campaign took place in Northeastern and Southwestern PA in the summer of 2012. Compounds monitored included methane (CH4, ethane, carbon monoxide (CO, nitrogen dioxide, and Proton Transfer Reaction Mass Spectrometer (PTR-MS measured volatile organic compounds (VOC including oxygenated and aromatic VOC. The second campaign took place in Northeastern PA in the summer of 2015. The mobile monitoring data were analyzed using interval percentile smoothing to remove bias from local unmixed emissions to isolate local-scale background concentrations. Comparisons were made to other ambient monitoring in the Marcellus region including a NOAA SENEX flight in 2013. Local background CH4 mole fractions were 140 ppbv greater in Southwestern PA compared to Northeastern PA in 2012 and background CH4 increased 100 ppbv from 2012 to 2015. CH4 local background mole fractions were not found to have a detectable relationship between well density or production rates in either region. In Northeastern PA, CO was observed to decrease 75 ppbv over the three year period. Toluene to benzene ratios in both study regions were found to be most similar to aged rural air masses indicating that the emission of aromatic VOC from Marcellus Shale activity may not be significantly impacting local background concentrations. In addition to understanding local background concentrations the ground-based mobile measurements were useful for investigating the composition of natural gas emissions in the region.

  6. Differences in airborne particle and gaseous concentrations in urban air between weekdays and weekends

    Science.gov (United States)

    Morawska, L.; Jayaratne, E. R.; Mengersen, K.; Jamriska, M.; Thomas, S.

    Airborne particle number concentrations and size distributions as well as CO and NO x concentrations monitored at a site within the central business district of Brisbane, Australia were correlated with the traffic flow rate on a nearby freeway with the aim of investigating differences between weekday and weekend pollutant characteristics. Observations over a 5-year monitoring period showed that the mean number particle concentration on weekdays was (8.8±0.1)×10 3 cm -3 and on weekends (5.9±0.2)×10 3 cm -3—a difference of 47%. The corresponding mean particle number median diameters during weekdays and weekends were 44.2±0.3 and 50.2±0.2 nm, respectively. The differences in mean particle number concentration and size between weekdays and weekends were found to be statistically significant at confidence levels of over 99%. During a 1-year period of observation, the mean traffic flow rate on the freeway was 14.2×10 4 and 9.6×10 4 vehicles per weekday and weekend day, respectively—a difference of 48%. The mean diurnal variations of the particle number and the gaseous concentrations closely followed the traffic flow rate on both weekdays and weekends (correlation coefficient of 0.86 for particles). The overall conclusion, as to the effect of traffic on concentration levels of pollutant concentration in the vicinity of a major road (about 100 m) carrying traffic of the order of 10 5 vehicles per day, is that about a 50% increase in traffic flow rate results in similar increases of CO and NO x concentrations and a higher increase of about 70% in particle number concentration.

  7. Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis

    Directory of Open Access Journals (Sweden)

    J. V. Niemi

    2006-01-01

    Full Text Available Aerosol samples were collected at a rural background site in southern Finland in May 2004 during pollution episode (PM1~16 µg m−3, backward air mass trajectories from south-east, intermediate period (PM1~5 µg m−3, backtrajectories from north-east and clean period (PM1~2 µg m−3, backtrajectories from north-west/north. The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were studied using transmission electron microscopy (TEM coupled with energy dispersive X-ray (EDX microanalyses. The TEM/EDX results were complemented with the size-segregated bulk chemical measurements of selected ions and organic and elemental carbon. Many of the particles in PM0.2–1 and PM1–3.3 size fractions were strongly internally mixed with S, C and/or N. The major particle types in PM0.2–1 samples were 1 soot and 2 (ammoniumsulphates and their mixtures with variable amounts of C, K, soot and/or other inclusions. Number proportions of those two particle groups in PM0.2–1 samples were 0–12% and 83–97%, respectively. During the pollution episode, the proportion of Ca-rich particles was very high (26–48% in the PM1–3.3 and PM3.3–11 samples, while the PM0.2–1 and PM1–3.3 samples contained elevated proportions of silicates (22–33%, metal oxides/hydroxides (1–9% and tar balls (1–4%. These aerosols originated mainly from polluted areas of Eastern Europe, and some open biomass burning smoke was also brought by long-range transport. During the clean period, when air masses arrived from the Arctic Ocean, PM1–3.3 samples contained mainly sea salt particles (67–89% with a variable rate of Cl substitution (mainly by NO3−. During the intermediate period, the PM1–3.3 sample contained porous (sponge-like Na-rich particles (35% with abundant S, K and O. They might originate from the burning of wood pulp wastes of paper industry. The proportion of biological particles and C-rich fragments

  8. A Miniature System for Separating Aerosol Particles and Measuring Mass Concentrations

    OpenAIRE

    Liang; Shih; Chen; Dai

    2010-01-01

    We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM) sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d < 2.28 μm, 2.28 μm ≤ d ≤ 3.20 μm, d > 3.20 μm. The QCM sensors were coated with a hy...

  9. Particle concentrations, gas-particle partitioning, and species intercorrelations for Polycyclic Aromatic Hydrocarbons (PAH) emitted during biomass burning

    Science.gov (United States)

    Jenkins, Bryan M.; Daniel Jones, A.; Turn, Scott Q.; Williams, Robert B.

    Eight types of agricultural and forest fuels including 4 cereal crop residues and 4 wood fuels were burned in a combustion wind tunnel to simulate the open burning of biomass. Concentrations for 19 PAH species in particulate matter were found to range between 120 and 4000 mg kg -1, representing between 1 and 70% of total PAH emission. Weakly flaming spreading fires in the cereals were observed to produce higher levels of heavier PAH than more robust fires, with greater partitioning of PAH to the particle phase. Individual species concentrations appeared well correlated within groups based primarily on molecular weight, but no single species was observed to correlate with all others to serve as an indicator of PAH emission strength. Equilibrium gas-particle partitioning did not appear to be achieved within the 3-5 s residence time prior to sampling for sampling temperatures between 32 and 87°C, and in particular for the heavier species emitted from wood fuel pile fires with higher stack gas temperatures and shorter residence times. Total PAH emission, particle-phase concentrations, and fraction of PAH on particles were more strongly influenced by burning conditions than by fuel type.

  10. Contrast in air pollution components between major streets and background locations: Particulate matter mass, black carbon, elemental composition, nitrogen oxide and ultrafine particle number

    Science.gov (United States)

    Boogaard, Hanna; Kos, Gerard P. A.; Weijers, Ernie P.; Janssen, Nicole A. H.; Fischer, Paul H.; van der Zee, Saskia C.; de Hartog, Jeroen J.; Hoek, Gerard

    2011-01-01

    Policies to reduce outdoor air pollution concentrations are often assessed on the basis of the regulated pollutants. Whether these are the most appropriate components to assess the potential health benefits is questionable, as other health-relevant pollutants may be more strongly related to traffic. The aim of this study is to compare the contrast in concentration between major roads and (sub)urban background for a large range of pollutants and to analyze the magnitude of the measured difference in the street - background for major streets with different street configurations. Measurements of PM 10, PM 2.5, particle number concentrations (PNC), black carbon (BC), elemental composition of PM 10 and PM 2.5 and NO x were conducted simultaneously in eight major streets and nine (sub)urban background locations in the Netherlands. Measurements were done six times for a week during a six month period in 2008. High contrasts between busy streets and background locations in the same city were found for chromium, copper and iron (factor 2-3). These elements were especially present in the coarse fraction of PM. In addition, high contrasts were found for BC and NO x (factor 1.8), typically indicators of direct combustion emissions. The contrast for PNC was similar to BC. NO 2 contrast was lower (factor 1.5). The largest contrast was found for two street canyons and two streets with buildings at one side of the street only. The contrast between busy streets and urban background in NO 2 was less than the contrast found for BC, PNC and elements indicative of non-exhaust emissions, adding evidence that NO 2 is not representing (current) traffic well. The study supports a substantial role for non-exhaust emissions including brake- and tyre wear and road dust in addition to direct combustion emissions. Significant underestimation of disease burden may occur when relying too much on the regulated components.

  11. Effect of Particle Concentration on Ablation Behavior of Carbon/Carbon Composites

    Directory of Open Access Journals (Sweden)

    ZHA Bai-lin

    2016-07-01

    Full Text Available A self-designed oxygen-kerosene ablation system was employed to study the ablation mechanism and performance of the carbon-carbon composites. Particle concentrations of the gas-solid two-phase ablation flow were 0, 1.37%, 2.22%, and 2.64% respectively. The microstructure of post-test samples was analysed through the scanning electron microscope (SEM, and the ablation rate was calculated. The influence principle of particle concentrations on the ablation rate of the carbon-carbon composites was studied, and the mechanism of ablation was analysed. Experiment results show that with no particles involved the mass ablation rate is 0.159g/s and the linear ablation rate is 0.175mm/s, while with particles introduced, the minimum mass ablation rate and linear ablation rate are 0.432g/s and 0.843mm/s respectively, with the increase of particle concentrations, the ablation rate becomes accelerated. Particle erosion makes the ablation of sample seriously intensified, and the ablation gradient of radial fiber on erosion surface is increased with the increase of particle concentrations as well.

  12. Inter-comparison of interpolated background nitrogen dioxide concentrations across Greater Manchester, UK

    Science.gov (United States)

    Lindley, S. J.; Walsh, T.

    There are many modelling methods dedicated to the estimation of spatial patterns in pollutant concentrations, each with their distinctive advantages and disadvantages. The derivation of a surface of air quality values from monitoring data alone requires the conversion of point-based data from a limited number of monitoring stations to a continuous surface using interpolation. Since interpolation techniques involve the estimation of data at un-sampled points based on calculated relationships between data measured at a number of known sample points, they are subject to some uncertainty, both in terms of the values estimated and their spatial distribution. These uncertainties, which are incorporated into many empirical and semi-empirical mapping methodologies, could be recognised in any further usage of the data and also in the assessment of the extent of an exceedence of an air quality standard and the degree of exposure this may represent. There is a wide range of available interpolation techniques and the differences in the characteristics of these result in variations in the output surfaces estimated from the same set of input points. The work presented in this paper provides an examination of uncertainties through the application of a number of interpolation techniques available in standard GIS packages to a case study nitrogen dioxide data set for the Greater Manchester conurbation in northern England. The implications of the use of different techniques are discussed through application to hourly concentrations during an air quality episode and annual average concentrations in 2001. Patterns of concentrations demonstrate considerable differences in the estimated spatial pattern of maxima as the combined effects of chemical processes, topography and meteorology. In the case of air quality episodes, the considerable spatial variability of concentrations results in large uncertainties in the surfaces produced but these uncertainties vary widely from area to area

  13. Particle number concentration, size distribution and chemical composition during haze and photochemical smog episodes in Shanghai.

    Science.gov (United States)

    Wang, Xuemei; Chen, Jianmin; Cheng, Tiantao; Zhang, Renyi; Wang, Xinming

    2014-09-01

    The aerosol number concentration and size distribution as well as size-resolved particle chemical composition were measured during haze and photochemical smog episodes in Shanghai in 2009. The number of haze days accounted for 43%, of which 30% was severe (visibilitysmog episodes, about 5.89 times and 4.29 times those of clean days. The particle volume concentration and surface concentration in haze, photochemical smog and clean days were 102, 49, 15μm(3)/cm(3) and 949, 649, 206μm(2)/cm(3), respectively. As haze events got more severe, the number concentration of particles smaller than 50nm decreased, but the particles of 50-200nm and 0.5-1μm increased. The diurnal variation of particle number concentration showed a bimodal pattern in haze days. All soluble ions were increased during haze events, of which NH4(+), SO4(2-) and NO3(-) increased greatly, followed by Na(+), K(+), Ca(2+) and Cl(-). These ions were very different in size-resolved particles during haze and photochemical smog episodes. Copyright © 2014. Published by Elsevier B.V.

  14. A miniature system for separating aerosol particles and measuring mass concentrations.

    Science.gov (United States)

    Liang, Dao; Shih, Wen-Pin; Chen, Chuin-Shan; Dai, Chi-An

    2010-01-01

    We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM) sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d3.20 μm. The QCM sensors were coated with a hydrogel, which was found to be a reliable adhesive for capturing aerosol particles. The QCM sensor coated with hydrogel was used to measure the mass loading of particles by utilizing its characteristic of resonant frequency shift. An integrated system has been demonstrated.

  15. A Miniature System for Separating Aerosol Particles and Measuring Mass Concentrations

    Directory of Open Access Journals (Sweden)

    Dao Liang

    2010-04-01

    Full Text Available We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d < 2.28 μm, 2.28 μm ≤ d ≤ 3.20 μm, d > 3.20 μm. The QCM sensors were coated with a hydrogel, which was found to be a reliable adhesive for capturing aerosol particles. The QCM sensor coated with hydrogel was used to measure the mass loading of particles by utilizing its characteristic of resonant frequency shift. An integrated system has been demonstrated.

  16. Source apportionment of ambient particle number concentrations in central Los Angeles using positive matrix factorization (PMF

    Directory of Open Access Journals (Sweden)

    M. H. Sowlat

    2016-04-01

    Full Text Available In this study, the positive matrix factorization (PMF receptor model (version 5.0 was used to identify and quantify major sources contributing to particulate matter (PM number concentrations, using PM number size distributions in the range of 13 nm to 10 µm combined with several auxiliary variables, including black carbon (BC, elemental and organic carbon (EC/OC, PM mass concentrations, gaseous pollutants, meteorological, and traffic counts data, collected for about 9 months between August 2014 and 2015 in central Los Angeles, CA. Several parameters, including particle number and volume size distribution profiles, profiles of auxiliary variables, contributions of different factors in different seasons to the total number concentrations, diurnal variations of each of the resolved factors in the cold and warm phases, weekday/weekend analysis for each of the resolved factors, and correlation between auxiliary variables and the relative contribution of each of the resolved factors, were used to identify PM sources. A six-factor solution was identified as the optimum for the aforementioned input data. The resolved factors comprised nucleation, traffic 1, traffic 2 (with a larger mode diameter than traffic 1 factor, urban background aerosol, secondary aerosol, and soil/road dust. Traffic sources (1 and 2 were the major contributor to PM number concentrations, collectively making up to above 60 % (60.8–68.4 % of the total number concentrations during the study period. Their contribution was also significantly higher in the cold phase compared to the warm phase. Nucleation was another major factor significantly contributing to the total number concentrations (an overall contribution of 17 %, ranging from 11.7 to 24 %, with a larger contribution during the warm phase than in the cold phase. The other identified factors were urban background aerosol, secondary aerosol, and soil/road dust, with relative contributions of approximately 12

  17. Determinants of black carbon, particle mass and number concentrations in London transport microenvironments

    NARCIS (Netherlands)

    Rivas, Ioar; Kumar, Prashant; Hagen-Zanker, Alex; Andrade, Maria de Fatima; Slovic, Anne Dorothee; Pritchard, John P.; Geurs, Karst T.

    2017-01-01

    We investigated the determinants of personal exposure concentrations of commuters’ to black carbon (BC), ultrafine particle number concentrations (PNC), and particulate matter (PM1, PM2.5 and PM10) in different travel modes. We quantified the contribution of key factors that explain the variation of

  18. 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 organometallic compounds at the French national level ever being published, it was possible to conclude that over the last 10-20 years organotin concentrations in French river basins have decreased while MeHg concentration remained stable. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Primary versus secondary contributions to particle number concentrations in the European boundary layer

    Directory of Open Access Journals (Sweden)

    C. L. Reddington

    2011-12-01

    Full Text Available It is important to understand the relative contribution of primary and secondary particles to regional and global aerosol so that models can attribute aerosol radiative forcing to different sources. In large-scale models, there is considerable uncertainty associated with treatments of particle formation (nucleation in the boundary layer (BL and in the size distribution of emitted primary particles, leading to uncertainties in predicted cloud condensation nuclei (CCN concentrations. Here we quantify how primary particle emissions and secondary particle formation influence size-resolved particle number concentrations in the BL using a global aerosol microphysics model and aircraft and ground site observations made during the May 2008 campaign of the European Integrated Project on Aerosol Cloud Climate Air Quality Interactions (EUCAARI. We tested four different parameterisations for BL nucleation and two assumptions for the emission size distribution of anthropogenic and wildfire carbonaceous particles. When we emit carbonaceous particles at small sizes (as recommended by the Aerosol Intercomparison project, AEROCOM, the spatial distributions of campaign-mean number concentrations of particles with diameter >50 nm (N50 and >100 nm (N100 were well captured by the model (R2≥0.8 and the normalised mean bias (NMB was also small (−18% for N50 and −1% for N100. Emission of carbonaceous particles at larger sizes, which we consider to be more realistic for low spatial resolution global models, results in equally good correlation but larger bias (R2≥0.8, NMB = −52% and −29%, which could be partly but not entirely compensated by BL nucleation. Within the uncertainty of the observations and accounting for the uncertainty in the size of emitted primary particles, BL nucleation makes a statistically significant contribution to CCN

  20. Evolution of Size and Chemical Composition of Copper Concentrate Particles Oxidized Under Simulated Flash Smelting Conditions

    Science.gov (United States)

    Pérez-Tello, Manuel; Parra-Sánchez, Víctor R.; Sánchez-Corrales, Víctor M.; Gómez-Álvarez, Agustín; Brown-Bojórquez, Francisco; Parra-Figueroa, Roberto A.; Balladares-Varela, Eduardo R.; Araneda-Hernández, Eugenia A.

    2018-04-01

    An experimental study was conducted to elucidate the evolution of size and chemical composition of La Caridad copper concentrate particles during oxidation under simulated flash smelting conditions. Input variables tested included particle size and oxygen concentration in the process gas. The response variables included the size distributions, chemical composition, and morphology of the reacted particles at seven locations along a laboratory reactor. Particles with initial size reaction path involving rapid melting followed by collision and coalescence of reacting droplets during flight. Particles with sizes > 45 µm contained varying amounts of chalcopyrite and pyrite, and tended to either maintain or decrease their mean size upon oxidation. When size reduction was observed, dust was produced because of fragmentation, and the particles showed no evidence of collisions during flight. The main oxidation products detected in the particles consisted of matte, cuprospinel, and magnetite. A plot of the mean size divided by the mean size in the feed against the fraction of sulfur eliminated generalized the experimental data so far reported in the literature, and helped identify the reaction path followed by the particles.

  1. 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.

  2. Characterisation of sub-micron particle number concentrations and formation events in the western Bushveld Igneous Complex, South Africa

    Directory of Open Access Journals (Sweden)

    A. Hirsikko

    2012-05-01

    Full Text Available South Africa holds significant mineral resources, with a substantial fraction of these reserves occurring and being processed in a large geological structure termed the Bushveld Igneous Complex (BIC. The area is also highly populated by informal, semi-formal and formal residential developments. However, knowledge of air quality and research related to the atmosphere is still very limited in the area. In order to investigate the characteristics and processes affecting sub-micron particle number concentrations and formation events, air ion and aerosol particle size distributions and number concentrations, together with meteorological parameters, trace gases and particulate matter (PM were measured for over two years at Marikana in the heart of the western BIC. The observations showed that trace gas (i.e. SO2, NOx, CO and black carbon concentrations were relatively high, but in general within the limits of local air quality standards. The area was characterised by very high condensation sink due to background aerosol particles, PM10 and O3 concentration. The results indicated that high amounts of Aitken and accumulation mode particles originated from domestic burning for heating and cooking in the morning and evening, while during daytime SO2-based nucleation followed by the growth by condensation of vapours from industrial, residential and natural sources was the most probable source for large number concentrations of nucleation and Aitken mode particles. Nucleation event day frequency was extremely high, i.e. 86% of the analysed days, which to the knowledge of the authors is the highest frequency ever reported. The air mass back trajectory and wind direction analyses showed that the secondary particle formation was influenced both by local and regional pollution and vapour sources. Therefore, our observation of the annual cycle and magnitude of the particle formation and growth rates during

  3. 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.

  4. Measurement of airborne concentrations of radon-220 daughter products by alpha-particle spectrometry

    International Nuclear Information System (INIS)

    Kerr, G.D.; Ryan, M.T.; Perdue, P.T.

    1978-01-01

    The decay of naturally occurring uranium-238 and thorium-232 produces radon-222 and radon-220 isotopes which can escape into the atmosphere. If these radon gases become concentrated in air, their daughter products may present an inhalation hazard to man. The airborne concentrations of radon-222 can usually be measured very accurately in the presence of normal airborne concentrations of radon-220 and its daughters. In contrast, the measurements of the airborne concentrations of radon-220 daughters are usually complicated by the presence of radon-222 and its daughters even at normally occurring airborne concentrations. The complications involved in these measurements can be overcome in most situations by using an alpha particle spectrometer to distinguish the activity of radon-222 daughters from that due to radon-220 daughters collected on a filter. A practical spectrometer for field measurements of alpha particle activity on a filter is discussed

  5. Seasonal variation of coarse aerosol particle concentration at Syowa Station, Antarctica

    Directory of Open Access Journals (Sweden)

    Kazuo Osada

    2010-12-01

    Full Text Available Number-size distributions (D_p>0.3 μm of atmospheric aerosol particles were measured at Syowa Station, Antarctica, from February 2004 to January 2006. Volume concentrations of coarse particles (D_p 1.0-5.0 μm were low in December to January and high in the rest of the year. To identify factors controlling the seasonal variation of coarse particle concentrations at Syowa Station, seasonal variations of wind speed distribution over the Southern Ocean, sea ice extent, wind speed at the edge of sea ice and at Syowa Station, and seasonal patterns of backward air trajectories were compared with the volume concentrations of coarse particles. Patterns of backward air trajectories and changes in size distributions of coarse particles associated with sea ice extent suggest changes in major source areas of sea salt particles observed at Syowa Station: coastal areas near Syowa in February and March, but far north of the sea ice edge, around 60゜ south, in October.

  6. Exploring Soot Particle Concentration and Emissivity by Transient Thermocouples Measurements in Laminar Partially Premixed Coflow Flames

    Directory of Open Access Journals (Sweden)

    Gianluigi De Falco

    2017-02-01

    Full Text Available Soot formation in combustion represents a complex phenomenon that strongly depends on several factors such as pressure, temperature, fuel chemical composition, and the extent of premixing. The effect of partial premixing on soot formation is of relevance also for real combustion devices and still needs to be fully understood. An improved version of the thermophoretic particle densitometry (TPD method has been used in this work with the aim to obtain both quantitative and qualitative information of soot particles generated in a set of laminar partially-premixed coflow flames characterized by different equivalence ratios. To this aim, the transient thermocouple temperature response has been analyzed to infer particle concentration and emissivity. A variety of thermal emissivity values have been measured for flame-formed carbonaceous particles, ranging from 0.4 to 0.5 for the early nucleated soot particles up to the value of 0.95, representing the typical value commonly attributed to mature soot particles, indicating that the correct determination of the thermal emissivity is necessary to accurately evaluate the particle volume fraction. This is particularly true at the early stage of the soot formation, when particle concentration measurement is indeed particularly challenging as in the central region of the diffusion flames. With increasing premixing, an initial increase of particles is detected both in the maximum radial soot volume fraction region and in the central region of the flame, while the further addition of primary air determines the particle volume fraction drop. Finally, a modeling analysis based on a sectional approach has been performed to corroborate the experimental findings.

  7. 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

  8. Increased ultrafine particles and carbon monoxide concentrations are associated with asthma exacerbation among urban children

    Science.gov (United States)

    Evans, Kristin A.; Halterman, Jill S.; Hopke, Philip K.; Fagnano, Maria; Rich, David Q.

    2014-01-01

    Objectives Increased air pollutant concentrations have been linked to several asthma-related outcomes in children, including respiratory symptoms, medication use, and hospital visits. However, few studies have examined effects of ultrafine particles in a pediatric population. Our primary objective was to examine the effects of ambient concentrations of ultrafine particles on asthma exacerbation among urban children and determine whether consistent treatment with inhaled corticosteroids could attenuate these effects. We also explored the relationship between asthma exacerbation and ambient concentrations of accumulation mode particles, fine particles (≤ 2.5 micrograms [μm]; PM2.5), carbon monoxide, sulfur dioxide, and ozone. We hypothesized that increased 1 to 7 day concentrations of ultrafine particles and other pollutants would be associated with increases in the relative odds of an asthma exacerbation, but that this increase in risk would be attenuated among children receiving school-based corticosteroid therapy. Methods We conducted a pilot study using data from 3–10 year-old children participating in the School-Based Asthma Therapy trial. Using a time-stratified case-crossover design and conditional logistic regression, we estimated the relative odds of a pediatric asthma visit treated with prednisone (n=96 visits among 74 children) associated with increased pollutant concentrations in the previous 7 days. We re-ran these analyses separately for children receiving medications through the school-based intervention and children in a usual care control group. Results Interquartile range increases in ultrafine particles and carbon monoxide concentrations in the previous 7 days were associated with increases in the relative odds of a pediatric asthma visit, with the largest increases observed for 4-day mean ultrafine particles (interquartile range=2088 p/cm3; OR=1.27; 95% CI=0.90–1.79) and 7-day mean carbon monoxide (interquartile range=0.17 ppm; OR=1.63; 95

  9. Particle size and metals concentrations of dust from a paint manufacturing plant.

    Science.gov (United States)

    Huang, Siew Lai; Yin, Chun-Yang; Yap, Siaw Yang

    2010-02-15

    In this study, the particle size distribution and concentration of metallic elements of solvent- and water-based paint dust from bulk dust collected from dust-collecting hoppers were determined. The mean particle size diameter over a 12-week sampling period was determined using a particle size analyzer. The metals composition and concentration of the dust were determined via acid digestion technique followed by concentration analysis using inductively coupled plasma. The volume weighted mean particle diameters were found to be 0.941+/-0.016 and 8.185+/-0.201 microm for solvent- and water-based paint dust, respectively. The mean concentrations of metals in solvent-based paint dust were found to be 100+/-20.00 microg/g (arsenic), 1550+/-550.00 microg/g (copper), 15,680+/-11,780.00 microg/g (lead) and 30,460+/-10,580.00 microg/g (zinc) while the mean concentrations of metals in water-based paint dust were found to be 20.65+/-6.11 microg/g (arsenic), 9.14+/-14.65 microg/g (copper), 57.46+/-22.42 microg/g (lead) and 1660+/-1260 microg/g (zinc). Both paint dust types could be considered as hazardous since almost all of the dust particles were smaller than 10 microm. Particular emphasis on containment of solvent-based paint dust particles should be given since it was shown that they were very fine in size (<1 microm) and had high lead and zinc concentrations.

  10. 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.

  11. 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. © 2015 Wiley Periodicals, Inc.

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

    International Nuclear Information System (INIS)

    Zaki, S. S. O.; Ibrahim, M. N.; Katas, H.

    2015-01-01

    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.

  13. 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

  14. The "trapped fraction" and interfacial jumps of concentration in fission products release from coated fuel particles

    Science.gov (United States)

    Ivanov, A. S.; Rusinkevich, A. A.; Taran, M. D.

    2018-01-01

    The FP Kinetics computer code [1] designed for calculation of fission products release from HTGR coated fuel particles was modified to allow consideration of chemical bonding, effects of limited solubility and component concentration jumps at interfaces between coating layers. Curves of Cs release from coated particles calculated with the FP Kinetics and PARFUME [2] codes were compared. It has been found that the consideration of concentration jumps at silicon carbide layer interfaces allows giving an explanation of some experimental data on Cs release obtained from post-irradiation heating tests. The need to perform experiments for measurement of solubility limits in coating materials was noted.

  15. Aerosol concentration and particle size distributions in underground excavations of a hard coal mine.

    Science.gov (United States)

    Skubacz, Krystian; Wojtecki, Łukasz; Urban, Paweł

    2017-09-01

    Deposition of aerosols in the respiratory system depends inter alia on their size and the respiratory tract deposition is appreciable for nanometer-sized particles. This article presents the results of measurements of size distributions of aerosols in the range of several nanometers up to about 20 μm in the underground mine excavations of an active hard coal mine. The study included practically all particles of a respirable fraction. The results showed that a high concentration of fine and ultrafine aerosols occurs in key underground workplaces especially during mining machine operations, although their contribution to total mass concentration is usually negligible.

  16. Local cartography of persistent organic pollutants (PCDD/F, PCB) concentrations in soils of three French departments. How to define background concentrations?

    Science.gov (United States)

    Clozel, Blandine

    2017-04-01

    As part of the Regional Health Plan for the Rhône-Alpes area (France), a cartography of soil contamination by persistent organic pollutants (dioxins/furans (PCDD/PCDF) and polychlorinated biphenyls (PCB)) was undertaken in order to define the background concentrations of soils located away from point source pollution. In the natural environment, PCDD/PCDF and PCB comes from air pollution and accumulate in the upper part of the soils. To define the background concentration of persistent organic pollutants from diffuse atmospheric origin in soils, sampling was carried out within the first 5 centimeters of soils that have been very little anthropized and untilled for more than 15 years. In such soils mixing and dilution of the pollutants is very limited. 170 samples were collected following a systematic plan of grid type (mesh of 8 x 8 km) in an area of 14 000km2, avoiding soil of high altitude and from urban area. Beyond their total concentration, the ratio of the congeners of PCBs (7 indicators and 12 dioxin-like) and of the 17 dioxins/furans was also used for interpretation. As expected, the concentrations in pollutants are globally lower in the rural zones than in the more industrialized ones. However, the pollutants are relatively enriched in valleys, confirming that the meteorological conditions and the local topography play a significant role in the repartition of the diffuse atmospheric pollution. For the vast majority of samples, even some of those presenting the highest total concentration, the ratio of the various congeners argues for an ancient origin of the contamination. All studies at the French or European level of the atmospheric concentration of organic pollutants indicate a progressive decrease in emissions of these contaminants for about 20 years. However, the soils have been receptors since a long time and such pollutants have accumulated. The congeners ratio give evolved signature of pollution indicating, on one hand, it is mainly due to past

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

    Energy Technology Data Exchange (ETDEWEB)

    Sarker, M. R. I., E-mail: islamrabiul@yahoo.com; Saha, Manabendra, E-mail: manabendra.saha@adelaide.edu.au, E-mail: manab04me@gmail.com; Beg, R. A. [Department of Mechanical Engineering, Rajshahi University of Engineering and Technology, Rajshahi-6204 (Bangladesh)

    2016-07-12

    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.

  18. Contributions of Organic Sources to Atmospheric Aerosol Particle Concentrations and Growth

    Science.gov (United States)

    Russell, L. M.

    2017-12-01

    Organic molecules are important contributors to aerosol particle mass and number concentrations through primary emissions as well as secondary growth in the atmosphere. New techniques for measuring organic aerosol components in atmospheric particles have improved measurements of this contribution in the last 20 years, including Scanning Transmission X-ray Microscopy Near Edge X-ray Absorption Fine Structure (STXM-NEXAFS), Fourier Transform Infrared spectroscopy (FTIR), and High-Resolution Aerosol Mass Spectrometry (AMS). STXM-NEXAFS individual aerosol particle composition illustrated the variety of morphology of organic components in marine aerosols, the inherent relationships between organic composition and shape, and the links between atmospheric aerosol composition and particles produced in smog chambers. This type of single particle microscopy has also added to size distribution measurements by providing evidence of how surface-controlled and bulk-controlled processes contribute to the growth of particles in the atmosphere. FTIR analysis of organic functional groups are sufficient to distinguish combustion, marine, and terrestrial organic particle sources and to show that each of those types of sources has a surprisingly similar organic functional group composition over four different oceans and four different continents. Augmenting the limited sampling of these off-line techniques with side-by-side inter-comparisons to online AMS provides complementary composition information and consistent quantitative attribution to sources (despite some clear method differences). Single-particle AMS techniques using light scattering and event trigger modes have now also characterized the types of particles found in urban, marine, and ship emission aerosols. Most recently, by combining with off-line techniques, single particle composition measurements have separated and quantified the contributions of organic, sulfate and salt components from ocean biogenic and sea spray

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

    International Nuclear Information System (INIS)

    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 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 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 o polarization angle. The change in the optical extinction of light polarized at 54.74 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 o is always negative, the more

  20. Behaviour of solute and particle markers in the stomach of sheep given a concentrate diet

    International Nuclear Information System (INIS)

    Faichney, G.J.; Griffiths, D.A.

    1978-01-01

    Fistulated sheep given a concentrate diet were used to study the behaviour of solute ([ 51 Cr]EDTA) and particle ([ 103 Ru]phenanthroline) markers in the stomach under conditions of continuous feeding. An injection of a mixed dose of [ 51 Cr]EDTA and [ 103 Ru]phenanthroline was given into the rumen and the time course of marker concentrations in the rumen and the abomasum was recorded. The curves were analysed on the assumption that the stomach of the sheep could be represented as two mixing compartments (reticulo-rumen and abomasum) and a time delay (omasum). This model provided a very good description of the data. [ 103 Ru]-phenanthroline associated with small particles was retained in the rumen much longer than [ 51 Cr]EDTA. Although exchange of [ 103 Ru] phenanthroline occurred between large and small particle fractions, the results suggested that small particles may have been retained somewhat longer in the rumen than solutes. However, it was clear from the results that the mean retention times for particulate matter in the rumen could not be simply obtained using adsorbable markers. Cyclical fluctuations in the concentration of [ 51 Cr]EDTA in the rumen indicated that there were daily variations in net water flux in the rumen. The presence of protozoa was associated with much shorter retention times of both solutes and particles in the rumen. Protozoa were also associated with reduced rumen volumes. (author)

  1. 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.

  2. 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

  3. 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

  4. Rapid detection of lactobacillus and yeast concentrations using a particle size distribution analyser.

    Science.gov (United States)

    Kim, H; Park, K; Oh, S; Chang, I S

    2009-11-01

    To see the possibility of particle size distribution analyser (PSDA) in detecting concentration of lactobacillus contaminants in yeast fermentation. A PSDA was used to rapidly determine the size and concentration of lactobacillus and Saccharomyces cerevisiae. Data showed that the aerodynamic diameters of Lactobacillus casei and S. cerevisiae cells were around 0.63 and 2.9 microm, respectively, with both cultures showing a linear relationship between cell density and particle count on a size distribution curve of PSDA. In addition, Lactobacillus fermentum showed high similarity in bacterial size distribution and particle count numbers with L. casei. The PSDA also rapidly detected (within 1 min) the cell concentrations of S. cerevisiae and L. casei in a mixed sample with different concentration ratios with 10(7)-10(9) cells ml(-1) of detection range. PSDA was demonstrated to be useful for the rapid detection of lactobacillus and S. cerevisiae concentrations. This is the first report concerning PSDA to detect the concentration of bacteria and yeast. This method can be useful in the actual field during ethanol fermentation because of relatively easy handling and rapid detection.

  5. The effects of fluvial transport on radionuclide concentrations on different particle size classes

    International Nuclear Information System (INIS)

    Dyer, F.J.; Olley, J.M.

    1998-01-01

    This paper reports on the effects of grain abrasion and disaggregation on the distribution of 137 Cs with respect to particle size and the effects this may have on the use of 137 Cs for determining the origin of recent sediment. Cs-137 is a product of above ground nuclear testing and has been deposited on the earth's surface by rainfall. On contact with soil, 137 Cs is strongly adsorbed by soil particles and there is a direct correlation between 137 Cs concentration and decreasing particle size. Rapid adsorption means that 137 Cs is preferentially concentrated in surface soils, and it's subsequent redistribution by physical processes rather than chemical has lead to 137 Cs being widely used to study soil erosion

  6. Apparatus and method for concentrating and filtering particles suspended in a fluid

    Science.gov (United States)

    Fiechtner, Gregory J [Bethesda, MD; Cummings, Eric B [Livermore, CA; Singh, Anup K [Danville, CA

    2009-05-19

    Disclosed is a device for separating and concentrating particles suspended in a fluid stream by using dielectrophoresis (DEP) to trap and/or deflect those particles as they migrate through a fluid channel. The method uses fluid channels designed to constrain a liquid flowing through it to uniform electrokinetic flow velocities. This behavior is achieved by connecting deep and shallow sections of channels, with the channel depth varying abruptly along an interface. By careful design of abrupt changes in specific permeability at the interface, an abrupt and spatially uniform change in electrokinetic force can be selected. Because these abrupt interfaces also cause a sharp gradient in applied electric fields, a DEP force also can be established along the interface. Depending on the complex conductivity of the suspended particles and the immersion liquid, the DEP force can controllably complement or oppose the local electrokinetic force transporting the fluid through the channel allowing for manipulation of particles suspended in the transporting liquid.

  7. Distribution of concentration of coarse particle-water mixture in horizontal smooth pipe

    Czech Academy of Sciences Publication Activity Database

    Vlasák, Pavel; Chára, Zdeněk; Konfršt, Jiří; Krupička, Jan

    2016-01-01

    Roč. 94, č. 6 (2016), s. 1040-1047 ISSN 0008-4034 R&D Projects: GA ČR GAP105/10/1574 Institutional support: RVO:67985874 Keywords : coarse particle-water mixture * gamma-ray radiometry * concentration distribution * horizontal conveying Subject RIV: BK - Fluid Dynamics Impact factor: 1.356, year: 2016

  8. How the Hawking radiation affect quantum Fisher information of Dirac particles in the background of a Schwarzschild black hole

    Science.gov (United States)

    Huang, ChunYu; Ma, Wen-chao; Wang, Dong; Ye, Liu

    2018-01-01

    In this work, the effect of Hawking radiation on the quantum Fisher information (QFI) of Dirac particles is investigated in the background of a Schwarzschild black hole. Interestingly, it has been verified that the QFI with respect to the weight parameter θ of a target state is always independent of the Hawking temperature T. This implies that if we encode the information on the weight parameter, then we can affirm that the corresponding accuracy of the parameter estimation will be immune to the Hawking effect. Besides, it reveals that the QFI with respect to the phase parameter φ exhibits a decay behavior with the increase in the Hawking temperature T and converges to a nonzero value in the limit of infinite Hawking temperature T. Remarkably, it turns out that the function F_φ on θ =π \\big /4 symmetry was broken by the influence of the Hawking radiation. Finally, we generalize the case of a three-qubit system to a case of a N-qubit system, i.e., |ψ > _{1,2,3,\\ldots ,N} =(cos θ | 0 > ^{⊗ N}+sin θ e^{iφ }| 1 > ^{⊗ N}) and obtain an interesting result: the number of particles in the initial state does not affect the QFI F_θ , nor the QFI F_φ . However, with the increasing number of particles located near the event horizon, F_φ will be affected by Hawking radiation to a large extent, while F_θ is still free from disturbance resulting from the Hawking effects.

  9. 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.

  10. Radioecology teaching: evaluation of the background radiation levels from areas with high concentrations of radionuclides in soil

    International Nuclear Information System (INIS)

    Anjos, R M; Okuno, E; Gomes, P R S; Veiga, R; Estellita, L; Mangia, L; Uzeda, D; Soares, T; Facure, A; Brage, J A P; Mosquera, B; Carvalho, C; Santos, A M A

    2004-01-01

    The study of environmental radioactivity is a topic which is not usually included in physics courses in Brazilian and Latin American universities. Consequently, high-school teachers are not able to show experimentally or discuss with their students the effects of exposure to terrestrial radiation. This paper presents a laboratory experiment in a teaching programme on the physics of ionizing radiation. It is based on the evaluation of the background radiation levels from areas with high concentrations of natural or artificial radionuclides in the soil. A brief analysis of the theory behind the technique and a description of some measurements, including their interpretations, are presented

  11. 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.

  12. Ultrafine particles in inhabited areas in the Arctic - From very low to high concentrations

    DEFF Research Database (Denmark)

    Pétursdóttir, Una; Kirkelund, Gunvor Marie; Press-Kristensen, Kåre

    2017-01-01

    The Arctic is considered a pristine environment, where pollution mainly originates from global sources. The present study examines particle number concentrations (PNCs) and the main sources of airborne ultrafine particles (UFPs, d < 100 nm) in the town Sisimiut and two nearby settlements, Sarfann......The Arctic is considered a pristine environment, where pollution mainly originates from global sources. The present study examines particle number concentrations (PNCs) and the main sources of airborne ultrafine particles (UFPs, d ..., Sarfannguit and Itilleq, in West Greenland. Measurements were carried out during three weeks in April and May 2016. Air temperatures during the measurements ranged from −4.4 to +8.7 °C. A portable condensation particle counter (P-Trak) was used for the measurements. Results showed that the lowest...... in Sisimiut, while subsequent measurements at the same location showed much lower PNCs. The presence of heavy machinery elevated PNCs highly during two measurement events, giving PNCs up to 270,993 cm−3 but dropping to 1180 cm−3 10 min later, after the vehicle had passed by. A measurement event in Sisimiut...

  13. Investigations of fine particles concentrations in the atmospheric air near highways

    Directory of Open Access Journals (Sweden)

    T.S. Ulanova

    2016-12-01

    Full Text Available This paper presents the results of the experimental determination of particulate matter PM 2,5 , PM 10 mass concentration and total suspended particles up to 15 microns (TSP, which are the priority components of air pollutants near the highways. The measurements were made during the year 2016 using a laser analyzer of aerosol DustTrak 8533. The study shows the dependence of the particulate matter concentration from the time of day and the traffic congestion. The sampling (N = 67 was performed due to brief program on the basis of the route monitoring station, which is located on the road junction with heavy traffic – up to1,200 vehicles per hour on the test sites. The single concentrations of the suspended substances reached the levels of the Maximum permissible concentration (MPC of 1.5. During the study period, the exceeding of the established average daily MPC for fine particles PM 2.5 and PM 10 fractions near the highways have not been identified. The significant linear relationship between the number of diesel vehicles on stops and the concentrations of particulate matter PM 2.5 , PM 10 , TSP (correlation coefficient from 0.62 to 0.65; Fisher's criterion of 14.2 to 38.0; p <0.05 has been established and parameterized, what allows to predict the level of air pollution by diesel vehicles when braking and accelerating. It is recommended to fulfill continuous monitoring of the average daily and single MPC of the fine suspended particles near the roads with traffic load of 769 – 1270 or more the diesel vehicles per every 20 minutes. The obtained data may be used in evaluation of the risk to public health induced by the transport emissions as well as in the estimation of the fine particles PM 2.5 , PM 10 concentrations on the sites close to the highways of the large industrial center.

  14. 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.)

  15. Measurement of radon progeny concentrations in air by alpha-particle spectrometey

    International Nuclear Information System (INIS)

    Kerr, G.D.

    1975-07-01

    A technique is presented for measuring air concentrations of the short-lived progeny of radon-222 by the use of alpha spectrometry. In this technique, the concentration of RaA, RaB, and RaC are calculated from one integral count of the RaA and two integral counts of the RaC' alpha-particle activity collected on a filter with an air sampling device. The influence of air sampling and counting intervals of time on the accuracy of the calculated concentrations is discussed in the report. A computer program is presented for use with this technique. It is written in the BASIC language. The program will calculate the air concentrations of RaA, RaB, and RaC, and will estimate the accuracy in these calculated concentrations. (U.S.)

  16. High concentrations of coarse particles emitted from a cattle feeding operation

    Directory of Open Access Journals (Sweden)

    N. Hiranuma

    2011-08-01

    Full Text Available Housing roughly 10 million head of cattle in the United States alone, open air cattle feedlots represent a significant but poorly constrained source of atmospheric particles. Here we present a comprehensive characterization of physical and chemical properties of particles emitted from a large representative cattle feedlot in the Southwest United States. In the summer of 2008, measurements and samplings were conducted at the upwind and downwind edges of the facility. A series of far-field measurements and samplings was also conducted 3.5 km north of the facility. Two instruments, a GRIMM Sequential Mobility Particle Sizer (SMPS and a GRIMM Portable Aerosol Spectrometer (PAS, were used to measure particle size distributions over the range of 0.01 to 25 μm diameter. Raman microspectroscopy was used to determine the chemical composition of particles on a single particle basis. Volume size distributions of dust were dominated by coarse mode particles. Twenty-four hour averaged concentrations of PM10 (particulate matter with a diameter of 10 μm or less were as high as 1200 μg m−3 during the campaign. The primary constituents of the particulate matter were carbonaceous materials, such as humic acid, water soluble organics, and less soluble fatty acids, including stearic acid and tristearin. A significant fraction of the organic particles was present in internal mixtures with salts. Basic characteristics such as size distribution and composition of agricultural aerosols were found to be different than the properties of those found in urban and semi-urban aerosols. Failing to account for such differences may lead to errors in estimates of aerosol effects on local air quality, visibility, and public health.

  17. 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

  18. Influence of lipid concentration on encapsulation and particle size in the development of liposomal irinotecan

    Directory of Open Access Journals (Sweden)

    A. V. Stadnichenko

    2017-04-01

    Full Text Available Purpose. For creation of liposomal irinotecan form, the influence of lipid concentration on the encapsulation of the active substance and nanoparticle size was necessary to investigate. Materials and methods. We used «chemical gradient" method for liposomes formulation, in the variety of “pH gradient”. Ammonium citrate at pH 2.5 was used as internal buffer. Lipid film was obtained, by evaporation technics with further high pressure homogenization with Microfluidics Microfluidizer M-110P apparatus. “Chemical gradient” was created by ultrafiltration, with “Minim 2” apparatus. Ultrafiltration cartridge with an upper cut-off 30 kDa was used. Encapsulation was measured using HPLC methods developed in variant of gel chromatography, with Shimadzu LC-20 instrument. The particle size was measured by laser diffraction method withe “Zetasizer Nano ZS” instrument. Results. For the preparation of liposomes was applied a constant lipid ratio with varying of total lipid concentration. The ratio of lipids in the experiment was a phosphatidylcholine / cholesterol 80/20 % by weight. A total concentration was investigated in range from 10 mg/ml to 30 mg/ml. The number of extrusion cycles consisted from 3 cycles at 1500 bar, in case of 10 mg/ml concentration, to 17 cycles at 1500 bar, in case of 30 mg/ml concentration. Conclusions. It was shown that the lipid concentration from 25 mg/ml led to particles formation with size more than 5000 nm, and it was not possible to reduce them by high pressure homogenization method. It was proven that the most optimal, in terms of technology and the final characteristics of liposomes, was lipids in concentration 20 mg/ml. The degree of encapsulation in this case was 82 ± 0.98 %. The size of the liposomes was 106 nm, 5000 nm particles were absent.

  19. Concentration Measurements of Suspended Load using ADV with Influence of the Particle Size

    Science.gov (United States)

    Schwarzwälder, Kordula

    2017-04-01

    ADV backscatter data can be used under certain conditions to gain information about the concentrations of suspended loads. This was shown in many studies before (Fugate and Friedrichs 2002; Chanson et al 2008; Ha et al. 2009). This paper reports on a pre-study to investigate the influence of particle size on concentration measurements for suspended sediment load with ADV. The study was conducted in a flume in the Oskar-von-Miller-Institute using fresh water from a river including the natural suspended load. The ADV used in the experiments was a Vectrino Profiler (Nortek). In addition water samples were taken for TSS and TOC. For the measurements a surge was generated in the flume to ensure that also particles of larger size will be present in the water phase. The measurements and samples were taken during the whole surge event. Therefore we were able to find a good correlation between the backscatter data of the ADV and the TSS as well as TOC results. For the decreasing part of the flow event the concentration of TOC in the suspended load of the water phase is decreasing much slower than the TSS and results in a damped decrease of the backscatter values. This means that the results for concentration measurements might be slightly influenced by the size of the particles. Further evaluations of measurements conducted with a LISST SL (Sequoia) will be investigated to show the trend of the particle sizes during this process and fortify this result. David C. Fugate, Carl T. Friedrichs, Determining concentration and fall velocity of estuarine particle populations using ADV, OBS and LISST, Continental Shelf Research, Volume 22, Issues 11-13, 2002 H.K. Ha, W.-Y. Hsu, J.P.-Y. Maa, Y.Y. Shao, C.W. Holland, Using ADV backscatter strength for measuring suspended cohesive sediment concentration, Continental Shelf Research, Volume 29, Issue 10, 2009 Hubert Chanson, Maiko Takeuchi, Mark Trevethan, Using turbidity and acoustic backscatter intensity as surrogate measures of

  20. Personal exposure to ultrafine particles: Two-level statistical modeling of background exposure and time-activity patterns during three seasons.

    Science.gov (United States)

    Deffner, Veronika; Küchenhoff, Helmut; Maier, Verena; Pitz, Mike; Cyrys, Josef; Breitner, Susanne; Schneider, Alexandra; Gu, Jianwei; Geruschkat, Uta; Peters, Annette

    2016-01-01

    Personal exposure to air pollution is associated with time- and location-specific factors including indoor and outdoor air pollution, meteorology and time activities. Our investigation aims at the description and identification of factors determining personal exposure to particle number concentration (PNC) in everyday situations. Ten volunteers recorded their personal exposure to PNC and kept an activity diary in three different seasons besides stationary measurements of ambient air pollution and meteorology. Background exposure to PNC was modelled using the most predictive variables. In a second step, the effects of the activities were calculated adjusted for the background exposure. The average personal PNC level was highest in winter and was three times higher than the mean stationary PNC level while staying indoors and two times higher while staying outdoors. Personal indoor PNC levels were significantly increased during the use of candles, cooking and the occurrence of smell of food. High stationary outdoor PNC levels and low dew point temperatures were associated with increased personal outdoor PNC levels. Times spent in public transport were associated with lower personal PNC levels than other times spent in transportation. Personal PNC levels in everyday situations exhibited a large variability because of seasonal, microenvironment-specific and activity-specific influences.

  1. 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

  2. Enhanced concentrations of ice nucleating particles in Svalbard during summer: Possible linkage with local dust emissions

    Science.gov (United States)

    Tobo, Y.; Adachi, K.; Nagatsuka, N.; DeMott, P. J.; Hill, T. C. J.; Ohata, S.; Kondo, Y.; Koike, M.

    2017-12-01

    Mixed-phase clouds, composed of both ice crystals and supercooled water droplets, occur frequently in the Arctic lower troposphere throughout the year. It is suggested that the existence of aerosol particles serving as ice nucleating particles (INPs) plays an important role in forming ice in mixed-phase clouds. However, little is known about the amounts and sources of INPs in the Arctic. In this presentation, we report on the results of the measurements of immersion-mode INPs at the Zeppelin Observatory (475 m AMSL) in Ny-Ålesund, Svalbard, during an intensive field campaign in July 2016. The results show that INP number concentrations measured at the Zeppelin Observatory were about one order of magnitude higher than those in Arctic summer marine boundary layer reported previously (e.g., Bering Sea and Baffin Bay). Single particle analyses of ambient aerosol particles combined with backward trajectory analyses of air masses suggest that locally-emitted dust particles within the Svalbard region might be one of the dominant aerosol sources in this period. We further conducted freezing experiments with local dusts collected in Ny-Ålesund (i.e., glacial outwash sediments smaller than 5 μm) and confirmed that the dusts have ice nucleating activities comparable to or higher than fertile soil dusts collected at mid-latitudes. The X-ray diffraction analysis demonstrates that the Ny-Ålesund dusts contain rich illite, kaolinite and quartz, but less K-feldspar (known as a highly ice nucleation active mineral component). We also found that the Ny-Ålesund dusts significantly lose their ice nucleating abilities after H2O2 treatment, suggesting the presence of ice nucleation active organics. Finally, we estimate that the observed INP number concentrations at the Zeppelin Observatory may be roughly explained by local dust emissions in the Svalbard region, assuming the dust mass concentrations of about 0.01 to 1 μg m-3.

  3. Influence of medium range transport of particles from nucleation burst on particle number concentration within the urban airshed

    Directory of Open Access Journals (Sweden)

    H. C. Cheung

    2012-06-01

    Full Text Available An elevated particle number concentration (PNC observed during nucleation events could play a significant contribution to the total particle load and therefore to the air pollution in the urban environments. Therefore, a field measurement study of PNC was commenced to investigate the temporal and spatial variations of PNC within the urban airshed of Brisbane, Australia. PNC was monitored at urban (QUT, roadside (WOO and semi-urban (ROC areas around the Brisbane region during 2009. During the morning traffic peak period, the highest relative fraction of PNC reached about 5% at QUT and WOO on weekdays. PNC peaks were observed around noon, which correlated with the highest solar radiation levels at all three stations, thus suggesting that high PNC levels were likely to be associated with new particle formation caused by photochemical reactions. Wind rose plots showed relatively higher PNC for the NE direction, which was associated with industrial pollution, accounting for 12%, 9% and 14% of overall PNC at QUT, WOO and ROC, respectively. Although there was no significant correlation between PNC at each station, the variation of PNC was well correlated among three stations during regional nucleation events. In addition, PNC at ROC was significantly influenced by upwind urban pollution during the nucleation burst events, with the average enrichment factor of 15.4. This study provides an insight into the influence of regional nucleation events on PNC in the Brisbane region and it the first study to quantify the effect of urban pollution on semi-urban PNC through the nucleation events.

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

    International Nuclear Information System (INIS)

    Yang, C.-R.; Lin, T.-C.; Chang, F.-H.

    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 ± 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

  5. Effect of particle size distribution and concentration on flow behavior of dense slurries

    Czech Academy of Sciences Publication Activity Database

    Vlasák, Pavel; Chára, Zdeněk

    2011-01-01

    Roč. 29, č. 1 (2011), s. 53-65 ISSN 0272-6351 R&D Projects: GA ČR(CZ) GAP105/10/1574 Institutional research plan: CEZ:AV0Z20600510 Keywords : concentration effect * dense complex slurry * experimental investigation * flow behavior * particle size distribution effect * pressure drop Subject RIV: BK - Fluid Dynamics Impact factor: 0.545, year: 2011

  6. Flow behaviour and local concentration of coarse particles-water mixture in inclined pipes

    Czech Academy of Sciences Publication Activity Database

    Vlasák, Pavel; Chára, Zdeněk; Konfršt, Jiří

    2017-01-01

    Roč. 65, č. 2 (2017), s. 183-191 ISSN 0042-790X R&D Projects: GA ČR GAP105/10/1574 Institutional support: RVO:67985874 Keywords : coarse particle mixture * concentration distribution * effect of pipe inclination * gamma-ray radiometry * Hydraulic conveying * mixture flow behaviour Subject RIV: BK - Fluid Dynamics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 1.654, year: 2016

  7. 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

    air was recirculated through the unit during two weeks in a randomized and double blinded design. The measurements included concentration of PM2.5 and ultrafine particles (UPC), carbon dioxide, temperature and relative humidity, ventilation, air flow through the unit, allergen and fungal levels....... Additional information was collected through questionnaires. Several medical tests were made, however the results are not included in this paper. Preliminary results showed significant decrease in PM2.5 concentration during the filtered period compared to placebo period. Likewise was UPC significantly lower...

  8. Using depolarization to quantify ice nucleating particle concentrations: a new method

    Directory of Open Access Journals (Sweden)

    J. Zenker

    2017-12-01

    Full Text Available We have developed a new method to determine ice nucleating particle (INP concentrations observed by the Texas A&M University continuous flow diffusion chamber (CFDC under a wide range of operating conditions. In this study, we evaluate differences in particle optical properties detected by the Cloud and Aerosol Spectrometer with POLarization (CASPOL to differentiate between ice crystals, droplets, and aerosols. The depolarization signal from the CASPOL instrument is used to determine the occurrence of water droplet breakthrough (WDBT conditions in the CFDC. The standard procedure for determining INP concentration is to count all particles that have grown beyond a nominal size cutoff as ice crystals. During WDBT this procedure overestimates INP concentration, because large droplets are miscounted as ice crystals. Here we design a new analysis method based on depolarization ratio that can extend the range of operating conditions of the CFDC. The method agrees reasonably well with the traditional method under non-WDBT conditions with a mean percent error of ±32.1 %. Additionally, a comparison with the Colorado State University CFDC shows that the new analysis method can be used reliably during WDBT conditions.

  9. Comparison of two estimation methods for surface area concentration using number concentration and mass concentration of combustion-related ultrafine particles

    Science.gov (United States)

    Park, Ji Young; Raynor, Peter C.; Maynard, Andrew D.; Eberly, Lynn E.; Ramachandran, Gurumurthy

    Recent research has suggested that the adverse health effects caused by nanoparticles are associated with their surface area (SA) concentrations. In this study, SA was estimated in two ways using number and mass concentrations and compared with SA (SA meas) measured using a diffusion charger (DC). Aerosol measurements were made twice: once starting in October 2002 and again starting in December 2002 in Mysore, India in residences that used kerosene or liquefied petroleum gas (LPG) for cooking. Mass, number, and SA concentrations and size distributions by number were measured in each residence. The first estimation method (SA PSD) used the size distribution by number to estimate SA. The second method (SA INV) used a simple inversion scheme that incorporated number and mass concentrations while assuming a lognormal size distribution with a known geometrical standard deviation. SA PSD was, on average, 2.4 times greater (range = 1.6-3.4) than SA meas while SA INV was, on average, 6.0 times greater (range = 4.6-7.7) than SA meas. The logarithms of SA PSD and SA INV were found to be statistically significant predictors of the logarithm of SA meas. The study showed that particle number and mass concentration measurements can be used to estimate SA with a correction factor that ranges between 2 and 6.

  10. 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

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

    DEFF Research Database (Denmark)

    Nguyen, Q. T.; Glasius, Marianne; Sørensen, Lise L.

    2016-01-01

    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 numbe...... 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. © Author(s) 2016....

  12. Contribution of road traffic to ambient fine particle concentrations (PM{sub 10}) in Switzerland

    Energy Technology Data Exchange (ETDEWEB)

    Hueglin, Ch.; Devos, W.; Gehrig, R.; Hofer, P.; Kobler, J. [Swiss Federal Laboratoires for Materials Testing and Research, EMPA, Dubendorf (Switzerland); Stahel, W.A. [Seminar for Statistics, ETH Zurich (Switzerland); Baltensperger, U. [Paul Scherrer Institute, Villigen PSI (Switzerland); Monn, Ch. [Institute for Hygiene and Applied Physiology, ETH Zurich (Switzerland)

    2000-07-01

    A multivariate receptor model was applied to estimate the contribution of road traffic to ambient levels of fine particles (PM{sub 10}) at different locations in Switzerland. At two roadside sites with heavy local traffic, the road traffic was found to account for 46% and 64% of PM{sub 10}. At an urban background site, the estimated average road traffic contribution was 34%, whereas a slightly higher value was obtained at a suburban site (36%). This results are in good agreement with the findings of a recent study, where a conceptually different approach (dispersion modelling) was applied. (authors)

  13. Hourly composition of gas and particle phase pollutants at a central urban background site in Milan, Italy

    Science.gov (United States)

    Bigi, A.; Bianchi, F.; De Gennaro, G.; Di Gilio, A.; Fermo, P.; Ghermandi, G.; Prévôt, A. S. H.; Urbani, M.; Valli, G.; Vecchi, R.; Piazzalunga, A.

    2017-04-01

    A comprehensive range of gas and particle phase pollutants were sampled at 1-hour time resolution in urban background Milan during summer 2012. Measurements include several soluble inorganic aerosols (Cl-, NO2-, NO3-, SO42-, Ca2+, K+, Mg2+, Na+, NH4+) and gases (HCl, HNO2,HNO3, NH3, NO, NO2,O3, SO2), organic, elemental and black carbon and meteorological parameters. Analysis methods used include mean diurnal pattern on weekdays and Sundays, pollution roses, bivariate polar plots and statistical models using backtrajectories. Results show how nitrous acid (HONO) was mainly formed heterogeneously at nighttime, with a dependence of its formation rate on NO2 consistent with observations during the last HONO campaign in Milan in summer 1998, although since 1998 a drop in HONO levels occurred following to the decrease of its precursors. Nitrate showed two main formation mechanisms: one occurring through N2O5 at nighttime and leading to nitrate formation onto existing particles; another occurring both daytime and nighttime following the homogeneous reaction of ammonia gas with nitric acid gas. Air masses reaching Milan influenced nitrate formation depending on their content in ammonia and the timing of arrival. Notwithstanding the low level of SO2 in Milan, its peaks were associated to point source emissions in the Po valley or shipping and power plant emissions SW of Milan, beyond the Apennines. A distinctive pattern for HCl was observed, featured by an afternoon peak and a morning minimum, and best correlated to atmospheric temperature, although it was not possible to identify any specific source. The ratio of primary-dominated organic carbon and elemental carbon on hourly PM2.5 resulted 1.7. Black carbon was highly correlated to elemental carbon and the average mass absorption coefficient resulted MAC = 13.8 ± 0.2 m2 g-1. It is noteworthy how air quality for a large metropolitan area, in a confined valley and under enduring atmospheric stability, is nonetheless

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

    Science.gov (United States)

    Sakaguchi, T.; Ehara, K.

    2011-02-01

    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%.

  15. Particle number and mass exposure concentrations by commuter transport modes in Milan, Italy

    Directory of Open Access Journals (Sweden)

    Senem Ozgen

    2016-03-01

    Full Text Available There is increasing awareness amongst the general public about exposure to atmospheric pollution while travelling in urban areas especially when taking active travelling modes such as walking and cycling. This study presents a comparative investigation of ultrafine particles (UFP, PM10, PM2.5, PM1 exposure levels associated with four transport modes (i.e., walking, cycling, car, and subway in the city of Milan measured by means of portable instruments. Significant differences in particle exposure between transport modes were found. The subway mode was characterized by the highest PM mass concentrations: PM10, PM2.5, PM1 subway levels were respectively about 2-4-3 times higher than those of the car and open air active modes (i.e. cycling and walking. Conversely, these latter modes displayed the highest UFP levels about 2 to 3 times higher than the subway and car modes, highlighting the influence of direct traffic emissions. The car mode (closed windows, air conditioning and air recirculation on reported the lowest PM and UFP concentration levels. In particular, the open-air/car average concentration ratio varied from about 2 for UFP up to 4 for PM1 and 6 for PM10 and PM2.5, showing differences that increase with increasing particle size. This work points out that active mode travelling in Milan city centre in summertime results in higher exposure levels than the car mode. Walkers’ and cyclists’ exposure levels is expected to be even higher during wintertime, due to the higher ambient PM and UFP concentration. Interventions intended to re-design the urban mobility should therefore include dedicated routes in order to limit their exposure to PM and UFP by increasing their distance from road traffic.

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

    Science.gov (United States)

    Watson, J.L.

    1990-07-10

    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. 7 figs.

  17. 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.

  18. Measurements and predictors of on-road ultrafine particle concentrations and associated pollutants in Los Angeles

    Science.gov (United States)

    Fruin, S.; Westerdahl, D.; Sax, T.; Sioutas, C.; Fine, P. M.

    Motor vehicles are the dominant source of oxides of nitrogen (NO x), particulate matter (PM), and certain air toxics (e.g., benzene, 1,3-butadiene) in urban areas. On roadways, motor vehicle-related pollutant concentrations are typically many times higher than ambient concentrations. Due to high air exchange rates typical of moving vehicles, this makes time spent in vehicles on roadways a major source of exposure. This paper presents on-road measurements for Los Angeles freeways and arterial roads taken from a zero-emission electric vehicle outfitted with real-time instruments. The objective was to characterize air pollutant concentrations on roadways and identify the factors associated with the highest concentrations. Our analysis demonstrated that on freeways, concentrations of ultrafine particles (UFPs), black carbon, nitric oxide, and PM-bound polycyclic aromatic hydrocarbons (PM-PAH) are generated primarily by diesel-powered vehicles, despite the relatively low fraction (˜6%) of diesel-powered vehicles on Los Angeles freeways. However, UFP concentrations on arterial roads appeared to be driven primarily by proximity to gasoline-powered vehicles undergoing hard accelerations. Concentrations were roughly one-third of those on freeways. By using a multiple regression model for the freeway measurements, we were able to explain 60-70% of the variability in concentrations of UFP, black carbon, nitric oxide, and PM-PAH using measures of diesel truck density and hour of day (as an indicator of wind speed). Freeway concentrations of these pollutants were also well correlated with readily available annual average daily truck counts, potentially allowing improved population exposure estimates for epidemiology studies. Based on these roadway measurements and average driving time, it appears that 33-45% of total UFP exposure for Los Angeles residents occurs due to time spent traveling in vehicles.

  19. Measurements and predictors of on-road ultrafine particle concentrations and associated pollutants in Los Angeles

    International Nuclear Information System (INIS)

    Fruin, S.; Sioutas, C.

    2008-01-01

    Motor vehicles are the dominant source of oxides of nitrogen (NO x ), particulate matter(PM), and certain air toxics (e.g., benzene, 1,3-butadiene) in urban areas. On roadways, motor vehicle-related pollutant concentrations are typically many times higher than ambient concentrations. Due to high air exchange rates typical of moving vehicles, this makes time spent in vehicles on roadways a major source of exposure. This paper presents on-road measurements for Los Angeles freeways and arterial roads taken from a zero-emission electric vehicle outfitted with real-time instruments. The objective was to characterize air pollutant concentrations on roadways and identify the factors associated with the highest concentrations. Our analysis demonstrated that on freeways, concentrations of ultrafine particles (UFPs), black carbon, nitric oxide, and PM-bound polycyclic aromatic hydrocarbons (PM-PAH) are generated primarily by diesel-powered vehicles, despite the relatively low fraction (∼6%) of diesel-powered vehicles on Los Angeles freeways. However, UFP concentrations on arterial roads appeared to be driven primarily by proximity to gasoline-powered vehicles undergoing hard accelerations. Concentrations were roughly one-third of those on freeways. By using a multiple regression model for the freeway measurements, we were able to explain 60-70% of the variability in concentrations of UFP, black carbon, nitric oxide, and PM-PAH using measures of diesel truck density and hour of day (as an indicator of wind speed). Freeway concentrations of these pollutants were also well correlated wth readily available annual average daily truck counts, potentially allowing improved population exposure estimates for epidemiology studies. Based on these roadway measurements and average driving time, it appears that 33-45% of total UFP exposure for Los Angeles residents occurs due to time spent traveling in vehicles. (author)

  20. Sensitive Detection and Identification of Isovanillin Aerosol Particles at the pg/cm3 Mass Concentration Level using Raman Spectroscopy

    Science.gov (United States)

    2017-04-24

    mass 152.15; Density 1.41) aerosol particles of mass concentration MC of 1.8...Aerosol Particles at the pg/cm3 Mass Concentration Level Using Raman Spectroscopy* R. L. Aggarwal1, S. Di Cecca, L. W. Farrar, Shabshelowitz, A...detect isovanillin aerosols with mass concentration of 12 pg/cm3 in a 15 s signal integration period with a signal‐to‐noise ratio of 32. We

  1. Dynamics of suspended sediment concentration, flow discharge and sediment particle size interdependency to identify sediment source

    Science.gov (United States)

    Sadeghi, Seyed Hamidreza; Singh, Vijay P.

    2017-11-01

    Spatiotemporal behavior of sediment yield is a key for proper watershed management. This study analyzed statistical characteristics and trends of suspended sediment concentration (SCS), flow discharge (FD) and sediment particle sizes using data from 24 gage stations scattered throughout the United States. Analysis showed significant time- and location-specific differences of these variables. The median values of SSC, FD and percentage of particle sizes smaller than 63 μm (P63) for all 24 gage stations were found to be 510.236 mg l-1 (right skewed), 45.406 m3 s-1 (left skewed) and 78.648% (right skewed), respectively. Most of the stations exhibited significant trends (P type and erosivity, watershed area, and soil erodibility) and human-affected (i.e., land use and hydraulic structures and water resources management) factors governing the study variables.

  2. Size-Resolved Characterization of Particles and Fibers Released during Abrasion of Fiber-Reinforced Composite in a Workplace Influenced by Ambient Background Sources

    DEFF Research Database (Denmark)

    Kling, Kirsten I.; Levin, Marcus; Jensen, Alexander C. O.

    2016-01-01

    We demonstrate the use of high-to low-resolution microscopy and particle chemical analysis during normal vacuum and cryo-conditions to identify the nature and relative abundances of process-generated particles and fibers from sanding of a glass and carbon fiber epoxy layer-composite in a workplace...... of ambient particles to the background in the production facility was observed in the sub-micron size range. Fibers are posing a dominant exposure risk in the micron size range, with carbon fibers dominating in count....

  3. Estimating the concentration of indoor particles of outdoor origin: a review.

    Science.gov (United States)

    Diapouli, E; Chaloulakou, A; Koutrakis, P

    2013-10-01

    Recent toxicological results highlight the importance of separating exposure to indoor- and outdoor-generated particles, due to their different physicochemical and toxicological properties. In this framework, a number of studies have attempted to estimate the relative contribution of particles of indoor and outdoor origins to indoor concentrations, using either statistical analysis of indoor and outdoor concentration time-series or mass balance equations. The aim of this work is to review and compare the methodologies developed in order to determine the ambient particle infiltration factor (F(INF)) (i.e., the fraction of ambient particles that enter indoors and remains suspended). The different approaches are grouped into four categories according to their methodological principles: (1) steady-state assumption using the steady-state form of the mass balance equation; (2) dynamic solution of the mass balance equation using complex statistical techniques; (3) experimental studies using conditions that simplify model calculations (e.g., decreasing the number of unknowns); and (4) infiltration surrogates using a particulate matter (PM) constituent with no indoor sources to act as surrogate of indoor PM of outdoor origin. Examination of the various methodologies and results reveals that estimating infiltration parameters is still challenging. The main difficulty lies in the separate calculation of penetration efficiency (P) and deposition rate (k). The values for these two parameters that are reported in the literature vary significantly. Deposition rate presents the widest range of values, both between studies and size fractions. Penetration efficiency seems to be more accurately calculated through the application of dynamic models. Overall, estimates of the infiltration factor generated using dynamic models and infiltration surrogates show good agreement. This is a strong argument in favor of the latter methodology, which is simple and easy to apply when chemical

  4. Genotoxic effects of daily personal exposure to particle mass and number concentrations on buccal cells

    Science.gov (United States)

    de Almeida, Daniela S.; da Costa, Silvano César; Ribeiro, Marcos; Moreira, Camila A. B.; Beal, Alexandra; Squizzato, Rafaela; Rudke, Anderson Paulo; Rafee, Sameh Adib Abou; Martins, Jorge A.; Palioto, Graciana Freitas; Kumar, Prashant; Martins, Leila D.

    2018-03-01

    The aim of this study is to assess personal exposure to Particle Number Concentrations (PNC) in four size ranges between 0.3 and 10 μm, and particulate matter (PM1; PM2.5; PM4; PM10) in order to evaluate possible genotoxic effects through a comet assay in buccal cells. A convenience cohort of 30 individuals from a Brazilian medium-sized city was selected. These individuals aged between 20 and 61 and worked in typical job categories (i.e., administrative, commerce, education, general services and transport). They were recruited to perform personal exposure measurements during their typical daily routine activities, totaling 240 h of sampling. The 8-h average mass concentrations in air for volunteers ranged from 2.4 to 31.8 μg m-3 for PM1, 4.2-45.1 μg m-3 for PM2.5, 7.9-66.1 μg m-3 for PM4 and from 23.1 to 131.7 μg m-3 for PM10. The highest PNC variation was found for 0.3-0.5 range, between 14 and 181 particles cm-3, 1 to 14 particles cm-3 for the 0.5-1.0 range, 0.2 to 2 particles cm-3 for the 1.0-2.5 range, and 0.06 to 0.7 particles cm-3 for the 2.5-10 range. Volunteers in the 'education' category experienced the lowest inhaled dose of PM2.5, as opposed to those involved in 'commercial' activities with the highest doses for PM10 (1.63 μg kg-1 h-1) and PM2.5 (0.61 μg kg-1 h-1). The predominant cause for these high doses was associated with the proximity of the workplace to the street and vehicle traffic. The comet assay performed in buccal cells indicated that the volunteers in 'commerce' category experienced the highest damage to their DeoxyriboNucleic Acid (DNA) compared with the control category (i.e. 'education'). These results indicate the variability in personal exposure of the volunteers in different groups, and the potential damage to DNA was much higher for those spending time in close proximity to the vehicle sources (e.g. commercial services) leading to exposure to a higher fraction of fine particles. This study builds understanding on the exposure

  5. The Contribution of Black Carbon to Ice Nucleating Particle Concentrations from Prescribed Burns and Wildfires

    Science.gov (United States)

    Schill, G. P.; DeMott, P. J.; Suski, K. J.; Emerson, E. W.; Rauker, A. M.; Kodros, J.; Levin, E. J.; Hill, T. C. J.; Farmer, D.; Pierce, J. R.; Kreidenweis, S. M.

    2017-12-01

    Black carbon (BC) has been implicated as a potential immersion-mode ice nucleating particle (INP) because of its relative abundance in the upper troposphere. Furthermore, several field and aircraft measurements have observed positive correlations between BC and INP concentrations. Despite this, the efficiency of BC to act as an immersion-mode INP is poorly constrained. Indeed, previous results from laboratory studies are in conflict, with estimates of BC's impact on INP ranging from no impact to being efficient enough to rival the well-known INP mineral dust. It is, however, becoming clear that the ice nucleation activity of BC may depend on both its fuel type and combustion conditions. For example, previous work has shown that diesel exhaust BC is an extremely poor immersion-mode INP, but laboratory burns of biomass fuels indicate that BC can contribute up to 70% of all INP for some fuel types. Given these dependencies, we propose that sampling from real-world biomass burning sources would provide the most useful new information on the contribution of BC to atmospheric INP. In this work, we will present recent results looking at the sources of INP from prescribed burns and wildfires. To determine the specific contribution of refractory black carbon (rBC) to INP concentrations, we utilized a new technique that couples the Single Particle Soot Photometer (SP2) to the Colorado State University Continuous Flow Diffusion Chamber (CFDC). The SP2 utilizes laser-induced incandescence to quantify rBC mass on a particle-by-particle basis; in doing so, it also selectively destroys rBC particles by heating them to their vaporization temperature. Thus, the SP2 can be used as a selective pre-filter for rBC into the CFDC. Furthermore, we have also used a filter-based technique for measuring INP, the Ice Spectrometer, which can employ pretreatments such as heating and digestion by H2O2 to determine the contribution of heat-labile and organic particles, respectively.

  6. Ultrafine particle concentrations and exposures in six elementary school classrooms in northern California.

    Science.gov (United States)

    Mullen, N A; Bhangar, S; Hering, S V; Kreisberg, N M; Nazaroff, W W

    2011-02-01

    Potential health risks may result from environmental exposure to ultrafine particles (UFP), i.e., those smaller than 0.1 μm in diameter. One important exposure setting that has received relatively little attention is school classrooms. We made time-resolved, continuous measurements of particle number (PN) concentrations for 2-4 school days per site (18 days total) inside and outside of six classrooms in northern California during normal occupancy and use. Additional time-resolved information was gathered on ventilation conditions, occupancy, and classroom activity. Across the six classrooms, average indoor PN concentrations when students were present were 5200-16,500/cm(3) (overall average 10,800/cm(3)); corresponding outdoor concentrations were 9000-26,000/cm(3) (overall average 18,100/cm(3)). Average indoor levels were higher when classrooms were occupied than when they were unoccupied because of higher outdoor concentrations and higher ventilation rates during occupancy. In these classrooms, PN exposures appear to be primarily attributable to outdoor sources. Indoor emission sources (candle use, cooking on an electric griddle, use of a heater, use of terpene-containing cleaning products) were seen to affect indoor PN concentrations only in a few instances. The daily-integrated exposure of students in these six classrooms averaged 52,000/cm(3) h/day for the 18 days monitored. This study provides data and insight concerning the UFP exposure levels children may encounter within classrooms and the factors that most significantly affect these levels in an urban area in northern California. This information can serve as a basis to guide further study of children's UFP exposure and the potential associated health risks. © 2010 John Wiley & Sons A/S.

  7. Measurements of ice nucleating particle concentrations at 242 K in the free troposphere

    Science.gov (United States)

    Lacher, L.; Lohmann, U.; Boose, Y.; Zipori, A.; Herrmann, E.; Bukowiecki, N.; Steinbacher, M.; Gute, E.; Kanji, Z. A.

    2017-12-01

    Clouds containing ice play an important role in the Earth's system, but some fundamental knowledge on their formation and further development is still missing. The phase change from vapor or liquid to ice in the atmosphere can occur heterogeneously in the presence of ice nucleating particles (INPs) at temperatures warmer, and supersaturations lower than required for homogeneous freezing. Only a small fraction of particles in an environment relevant for the occurrence of ice- and mixed-phase clouds are INPs, and their identification and quantification remains challenging. We measure INP concentrations with the ETH Horizontal Ice Nucleation Chamber (HINC) at the High Altitude Research Station Jungfraujoch (JFJ) during several field campaigns in different seasons and years. The measurements are performed at 242 K and above water saturation, representing ice- and mixed-phase clouds conditions. Due to its elevation of 3580 m a.s.l. the site encounters mostly free tropospheric conditions, and is influenced by boundary layer injections up to 80% of the time in summer. JFJ regularly encounters Saharan dust events and receives air masses of marine origin, which can both occur within the free troposphere. Our measurements show that INP concentrations in the free troposphere do not follow a seasonal cycle. They are remarkably constant, with concentrations from 0.5 - 8 L-1 (interquartile range), which compares well to measurements performed under the same conditions at another location within the free troposphere, the Izaña Atmospheric Research Station in Tenerife. At JFJ, correlations with parameters of physical properties of ambient particles, meteorology and air mass characteristics do not show a single best estimator to predict INP concentrations, emphasizing the complexity of ice nucleation in the free troposphere. Increases in INP concentrations of a temporary nature were observed in the free troposphere during Saharan dust events and marine air mass influence, which

  8. 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

  9. Time-series forecasting of pollutant concentration levels using particle swarm optimization and artificial neural networks

    Directory of Open Access Journals (Sweden)

    Francisco S. de Albuquerque Filho

    2013-01-01

    Full Text Available This study evaluates the application of an intelligent hybrid system for time-series forecasting of atmospheric pollutant concentration levels. The proposed method consists of an artificial neural network combined with a particle swarm optimization algorithm. The method not only searches relevant time lags for the correct characterization of the time series, but also determines the best neural network architecture. An experimental analysis is performed using four real time series and the results are shown in terms of six performance measures. The experimental results demonstrate that the proposed methodology achieves a fair prediction of the presented pollutant time series by using compact networks.

  10. Wide-range particle characterization and elemental concentration in Beijing aerosol during the 2013 Spring Festival.

    Science.gov (United States)

    Jing, Hui; Li, Yu-Feng; Zhao, Jiating; Li, Bai; Sun, Jialong; Chen, Rui; Gao, Yuxi; Chen, Chunying

    2014-09-01

    The number and mass concentration, size distribution, and the concentration of 16 elements were studied in aerosol samples during the Spring Festival celebrations in 2013 in Beijing, China. Both the number and mass concentration increased sharply in a wide range from 10 nm to 10 μm during the firecrackers and fireworks activities. The prominent increase of the number concentration was in 50 nm-500 nm with a peak of 1.7 × 10(5)/cm(3) at 150 nm, which is 8 times higher than that after 1.5 h. The highest mass concentration was in 320-560 nm, which is 4 times higher than the control. K, Mg, Sr, Ba and Pb increased sharply during the firework activities in PM10. Although the aerosol emission from firework activities is a short-term air quality degradation event, there may be a substantial hazard arising from the chemical composition of the emitted particles. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Height profile of particle concentration in an aeolian saltating cloud: A wind tunnel investigation by PIV MSD

    Science.gov (United States)

    Dong, Zhibao; Wang, Hongtao; Zhang, Xiaohang; Ayrault, Michael

    2003-10-01

    Attempt is made to define the particle concentration in an aeolian saltating cloud and its variation with height using artificial spherical quartz sand in a wind tunnel. The height profiles of the relative particle concentration in aeolian saltating cloud at three wind velocities were detected by the state of the art PIV (Particle Image Velocimetry) MSD (Mie Scattering Diffusion) technique, and converted to actual concentration based on sand transport rate and the variation with height of velocity of the saltating cloud. The particle concentration was found to decay exponentially with height and to increase with wind velocity. It decayed more rapidly when the wind velocity decreased. The volume/volume concentration in the near-surface layer was at the order of 10-4. The results obtained by PIV MSD technique were in good agreement with those derived from the sand flux and velocity profiles, the former being about 15% greater than the later.

  12. 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

  13. Flooding event impacts soil pH, Ca, and P concentration distribution in a cattle backgrounding site on karst topography.

    Science.gov (United States)

    Beef cattle backgrounding in US, function as an intermediate between cow-calf enterprises and feedlot finishing. Beef cattle backgrounding receives weaned calves of different growth stages from cow-calf operations and prepare them ready for feed lot finishing. Many beef cattle backgrounding operati...

  14. Effects of size and concentration of silt particles on flow and performance of a centrifugal pump under cavitating conditions

    Science.gov (United States)

    Zhao, Weiguo; Han, Xiangdong; Li, Rennian; Zheng, Yingjie; Wang, Yanyan

    2017-12-01

    To research effects of silt particles on the performance and cavitation flow fields, silt-laden cavitation flow was simulated in the centrifugal pump. Silt mean diameters are 0.005 mm and 0.010 mm and silt concentrations are 0.5% and 1.0%. Results show that silt particles with silt mean diameter 0.005 mm and silt concentration 1.0% and silt particles with silt mean diameter 0.010 mm and silt concentration 0.5% promote the development of cavitation and distribution range of vapor is larger than pure water. Effects of silt particles and cavitation make distribution range of turbulent kinetic energy larger than pure water and streamlines are more disorderedly. Silt particles with silt mean diameter 0.010 mm and silt concentration 1.0% have little effect on cavitation and distribution range of vapor is similar with pure water. Effects of silt particles make distribution range of turbulent kinetic energy larger than pure water and streamlines are more disorderedly than pure water. With the increase of silt mean diameter and silt concentration, head and efficiency decrease gradually. For silt particles promoting the evolution of cavitation, distribution range of turbulent kinetic energy is larger and streamlines are more disorderly than silt-laden cavitation flow with silt particles inhibiting the development of cavitation.

  15. 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.

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

    NARCIS (Netherlands)

    Ando, S.; Komatsu, E.

    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

  17. Coupling discrete and continuum concentration particle models for multiscale and hybrid molecular-continuum simulations

    Science.gov (United States)

    Petsev, Nikolai D.; Leal, L. Gary; Shell, M. Scott

    2017-12-01

    Hybrid molecular-continuum simulation techniques afford a number of advantages for problems in the rapidly burgeoning area of nanoscale engineering and technology, though they are typically quite complex to implement and limited to single-component fluid systems. We describe an approach for modeling multicomponent hydrodynamic problems spanning multiple length scales when using particle-based descriptions for both the finely resolved (e.g., molecular dynamics) and coarse-grained (e.g., continuum) subregions within an overall simulation domain. This technique is based on the multiscale methodology previously developed for mesoscale binary fluids [N. D. Petsev, L. G. Leal, and M. S. Shell, J. Chem. Phys. 144, 084115 (2016)], simulated using a particle-based continuum method known as smoothed dissipative particle dynamics. An important application of this approach is the ability to perform coupled molecular dynamics (MD) and continuum modeling of molecularly miscible binary mixtures. In order to validate this technique, we investigate multicomponent hybrid MD-continuum simulations at equilibrium, as well as non-equilibrium cases featuring concentration gradients.

  18. Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Vergara-Temprado, Jesús; Murray, Benjamin J.; Wilson, Theodore W.; O& amp; apos; Sullivan, Daniel; Browse, Jo; Pringle, Kirsty J.; Ardon-Dryer, Karin; Bertram, Allan K.; Burrows, Susannah M.; Ceburnis, Darius; DeMott, Paul J.; Mason, Ryan H.; O& amp; apos; Dowd, Colin D.; Rinaldi, Matteo; Carslaw, Ken S.

    2017-01-01

    Ice-nucleating particles (INPs) are known to affect the amount of ice in mixed-phase clouds, thereby influencing many of their properties. The atmospheric INP concentration changes by orders of magnitude from terrestrial to marine environments, which typically contain much lower concentrations. Many modelling studies use parameterizations for heterogeneous ice nucleation and cloud ice processes that do not account for this difference because they were developed based on INP measurements made predominantly in terrestrial environments without considering the aerosol composition. Errors in the assumed INP concentration will influence the simulated amount of ice in mixed-phase clouds, leading to errors in top-of-atmosphere radiative flux and ultimately the climate sensitivity of the model. Here we develop a global model of INP concentrations relevant for mixed-phase clouds based on laboratory and field measurements of ice nucleation by K-feldspar (an ice-active component of desert dust) and marine organic aerosols (from sea spray). The simulated global distribution of INP concentrations based on these two species agrees much better with currently available ambient measurements than when INP concentrations are assumed to depend only on temperature or particle size. Underestimation of INP concentrations in some terrestrial locations may be due to the neglect of INPs from other terrestrial sources. Our model indicates that, on a monthly average basis, desert dusts dominate the contribution to the INP population over much of the world, but marine organics become increasingly important over remote oceans and they dominate over the Southern Ocean. However, day-to-day variability is important. Because desert dust aerosol tends to be sporadic, marine organic aerosols dominate the INP population on many days per month over much of the mid- and high-latitude Northern Hemisphere. This study advances our understanding of which aerosol species need to be included in order to

  19. Enhancing effect of marine oligotrophy on environmental concentrations of particle-reactive trace elements

    International Nuclear Information System (INIS)

    Jeffree, R.A.; Szymczak, R.

    2000-01-01

    A biogeochemical model has been previously developed that explains the inverse and nonlinear relationship between Po-210 concentration in zooplankton and their biomass, under oligotrophic conditions in French Polynesia. In this study the model structure was reviewed to determine a set of biogeochemical behaviors of Po-210, proposed to be critical to its environmental enhancement under oligotrophy: this set was then used to identify 25 other elements with comparable behaviors to Po-210. Field investigation in the Timor Sea showed that four of these a priori identified elements, viz. Cd, Co, Pb, and Mn as well as Cr and Ni, showed elevated water concentrations with reduced particle removal rates in the euphotic zone, results that are consistent with those previously obtained for Po-210 and the proposed explanatory model. These findings point to the enhanced susceptibility to contamination with particle-reactive elements of oligotrophic marine systems, whose degree and geographic extent may be enhanced by projected increases in sea surface temperatures from global warming

  20. 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.

  1. Effects of concentrated ambient particles on normal and hypersecretory airways in rats.

    Science.gov (United States)

    Harkema, Jack R; Keeler, Gerald; Wagner, James; Morishita, Masako; Timm, Edward; Hotchkiss, Jon; Marsik, Frank; Dvonch, Timothy; Kaminski, Norbert; Barr, Edward

    2004-08-01

    .5 from this local urban atmosphere. Rats in the inhalation studies were exposed for 1 day or for 4 or 5 consecutive days (10 hours/day) to either filtered air (controls) or concentrated ambient particles (CAPs) delivered by a Harvard ambient fine particle concentrator. Rats were killed 24 hours after the end of the exposure. Biochemical, morphometric, and molecular techniques were used to identify airway epithelial and inflammatory responses to CAPs. Lung lobes were also either intratracheally lavaged with saline to determine cellular composition and protein in bronchoalveolar lavage fluid (BALF) or removed for analysis by inductively coupled plasma-mass spectrometry (ICPMS) to detect retention of ambient PM2.5--derived trace elements. The Harvard concentrator effectively concentrated the fine ambient particles from this urban atmosphere (10-30 times) without significantly changing the major physicochemical features of the atmospheric particles. Daily CAPs mass concentrations during the 10-hour exposure period (0800-1800) in July ranged from 16 to 895 microg/m3 and in September ranged from 81 to 755 microg/m3. In general, chemical characteristics of ambient particles were conserved through the concentrator into the exposure chamber. Single or repeated exposures to CAPs did not cause adverse effects in the nasal or pulmonary airways of healthy F344 or BN rats. In addition, CAPs-related toxicity was not observed in F344 rats pretreated with bacterial endotoxin. Variable airway responses to CAPs exposure were observed in BN rats with preexisting allergic airway disease induced by OVA sensitization and challenge. Only OVA-challenged BN rats exposed to CAPs for 5 consecutive days in September 2000 had significant increases in airway mucosubstances and pulmonary inflammation compared to saline-challenged/air-exposed control rats. OVA-challenged BN rats that were repeatedly exposed to CAPs in July 2000 had only minor CAPs-related effects. In only the September 5-day exposure

  2. Estimate of main local sources to ambient ultrafine particle number concentrations in an urban area

    Science.gov (United States)

    Rahman, Md Mahmudur; Mazaheri, Mandana; Clifford, Sam; Morawska, Lidia

    2017-09-01

    Quantifying and apportioning the contribution of a range of sources to ultrafine particles (UFPs, D urban environments. Although vehicular emissions have long been considered one of the major sources of ultrafine particles in urban areas, the contribution of other major urban sources is not yet fully understood. This paper aims to determine and quantify the contribution of local ground traffic, nucleated particle (NP) formation and distant non-traffic (e.g. airport, oil refineries, and seaport) sources to the total ambient particle number concentration (PNC) in a busy, inner-city area in Brisbane, Australia using Bayesian statistical modelling and other exploratory tools. The Bayesian model was trained on the PNC data on days where NP formations were known to have not occurred, hourly traffic counts, solar radiation data, and smooth daily trend. The model was applied to apportion and quantify the contribution of NP formations and local traffic and non-traffic sources to UFPs. The data analysis incorporated long-term measured time-series of total PNC (D ≥ 6 nm), particle number size distributions (PSD, D = 8 to 400 nm), PM2.5, PM10, NOx, CO, meteorological parameters and traffic counts at a stationary monitoring site. The developed Bayesian model showed reliable predictive performances in quantifying the contribution of NP formation events to UFPs (up to 4 × 104 particles cm- 3), with a significant day to day variability. The model identified potential NP formation and no-formations days based on PNC data and quantified the sources contribution to UFPs. Exploratory statistical analyses show that total mean PNC during the middle of the day was up to 32% higher than during peak morning and evening traffic periods, which were associated with NP formation events. The majority of UFPs measured during the peak traffic and NP formation periods were between 30-100 nm and smaller than 30 nm, respectively. To date, this is the first application of Bayesian model to

  3. Organic Nitrogen in Atmospheric Drops and Particles: Concentrations, (Limited) Speciation, and Chemical Transformations

    Science.gov (United States)

    Anastasio, C.; Zhang, Q.

    2003-12-01

    While quite a bit is known of the concentrations, speciation, and chemistry of inorganic forms of nitrogen in the atmosphere, the same cannot be said for organic forms. Despite this, there is growing evidence that organic N (ON) is ubiquitous in the atmosphere, especially in atmospheric condensed phases such as fog/cloud drops and aerosol particles. Although the major compounds that make up organic N are generally unknown, as are the sources of these compounds, it is clear that there are significant fluxes of ON between the atmosphere and ecosystems. It also appears that organic N can have significant effects in both spheres. The goal of our recent work in this area has been to better describe the atmospheric component of the biogeochemistry of organic nitrogen. Based on particle, gas, and fogwater samples from Northern California we have made three major findings: 1) Organic N represents a significant component, approximately 20%, of the total atmospheric N loading in these samples. This is broadly consistent with studies from other locations. 2) Amino compounds, primarily as combined amino acids, account for approximately 20% of the measured ON in our condensed phase samples. Given the properties of amino acids, these compounds could significantly affect the chemical and physical properties of atmospheric particles. 3) Organic nitrogen in atmospheric particles and drops is transformed to inorganic forms - primarily ammonium, nitrate, and nitrogen oxides (NOx) - during exposure to sunlight and/or ozone. These chemical reactions likely increase the bioavailability of the condensed phase nitrogen pool and enhance its biological effects after deposition to ecosystems.

  4. Size-resolved source apportionment of ambient particles by positive matrix factorization at Gosan background site in East Asia

    Directory of Open Access Journals (Sweden)

    J. S. Han

    2006-01-01

    Full Text Available Size- and time-resolved aerosol samples were collected using an eight-stage Davis rotating unit for monitoring (DRUM sampler from 29 March to 29 May in 2002 at Gosan, Jeju Island, Korea, which is one of the representative background sites in East Asia. These samples were analyzed using synchrotron X-ray fluorescence for 3-h average concentrations of 19 elements consisting of S, Si, Al, Fe, Ca, Cl, Cu, Zn, Ti, K, Mn, Pb, Ni, V, Se, As, Rb, Cr, Br. The size-resolved data sets were then analyzed using the positive matrix factorization (PMF technique in order to identify possible sources and estimate their contribution to particulate matter mass. PMF analysis uses the uncertainty of the measured data to provide an optimal weighting. Fifteen sources were resolved in eight size ranges (0.07~12 μm and included continental soil, local soil, sea salt, biomass/biofuel burning, coal combustion, oil heating furnace, residual oil fired boiler, municipal incineration, nonferrous metal source, ferrous metal source, gasoline vehicle, diesel vehicle, copper smelter and volcanic emission. PMF analysis of size-resolved source contributions showed that natural sources represented by local soil, sea salt and continental soil contributed about 79% to the predicted primary particulate matter (PM mass in the coarse size range (1.15~12 μm. On the other hand, anthropogenic sources such as coal combustion and biomass/biofuel burning contributed about 60% in the fine size range (0.56~2.5 μm. The diesel vehicle source contributed the most in the ultra-fine size range (0.07~0.56 μm and was responsible for about 52% of the primary PM mass.

  5. Determinants of black carbon, particle mass and number concentrations in London transport microenvironments

    Science.gov (United States)

    Rivas, Ioar; Kumar, Prashant; Hagen-Zanker, Alex; Andrade, Maria de Fatima; Slovic, Anne Dorothee; Pritchard, John P.; Geurs, Karst T.

    2017-07-01

    We investigated the determinants of personal exposure concentrations of commuters' to black carbon (BC), ultrafine particle number concentrations (PNC), and particulate matter (PM1, PM2.5 and PM10) in different travel modes. We quantified the contribution of key factors that explain the variation of the previous pollutants in four commuting routes in London, each covered by four transport modes (car, bus, walk and underground). Models were performed for each pollutant, separately to assess the effect of meteorology (wind speed) or ambient concentrations (with either high spatial or temporal resolution). Concentration variations were mainly explained by wind speed or ambient concentrations and to a lesser extent by route and period of the day. In multivariate models with wind speed, the wind speed was the common significant predictor for all the pollutants in the above-ground modes (i.e., car, bus, walk); and the only predictor variable for the PM fractions. Wind speed had the strongest effect on PM during the bus trips, with an increase in 1 m s-1 leading to a decrease in 2.25, 2.90 and 4.98 μg m-3 of PM1, PM2.5 and PM10, respectively. PM2.5 and PM10 concentrations in car trips were better explained by ambient concentrations with high temporal resolution although from a single monitoring station. On the other hand, ambient concentrations with high spatial coverage but lower temporal resolution predicted better the concentrations in bus trips, due to bus routes passing through streets with a high variability of traffic intensity. In the underground models, wind speed was not significant and line and type of windows on the train explained 42% of the variation of PNC and 90% of all PM fractions. Trains in the district line with openable windows had an increase in concentrations of 1 684 cm-3 for PNC and 40.69 μg m-3 for PM2.5 compared with trains that had non-openable windows. The results from this work can be used to target efforts to reduce personal exposures of

  6. Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS - diurnal variations and PMF receptor modelling

    Science.gov (United States)

    Dall'Osto, M.; Querol, X.; Amato, F.; Karanasiou, A.; Lucarelli, F.; Nava, S.; Calzolai, G.; Chiari, M.

    2013-04-01

    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 (1 h) and size (PM2.5 particulate matter Spain) during September-October 2010: an urban background site (UB) and a street canyon traffic road site (RS). Elements related to primary non-exhaust traffic emission (Fe, Cu), dust resuspension (Ca) and anthropogenic Cl were found enhanced at the RS, whereas industrial related trace metals (Zn, Pb, Mn) were found at higher concentrations at the more ventilated UB site. When receptor modelling was performed with positive matrix factorization (PMF), nine different aerosol sources were identified at both sites: three types of regional aerosols (regional sulphate (S) - 27%, biomass burning (K) - 5%, sea salt (Na-Mg) - 17%), three types of dust aerosols (soil dust (Al-Ti) - 17%, urban crustal dust (Ca) - 6%, and primary traffic non-exhaust brake dust (Fe-Cu) - 7%), and three types of industrial aerosol plumes-like events (shipping oil combustion (V-Ni) - 17%, industrial smelters (Zn-Mn) - 3%, and industrial combustion (Pb-Cl) - 5%, percentages presented are average source contributions to the total elemental mass measured). The validity of the PMF solution of the PIXE data is supported by very good correlations with external single particle mass spectrometry measurements. Some important conclusions can be drawn about the PM2.5 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

  7. African Anthropogenic Combustion Emissions: Estimate of Regional Mortality Attributable to Fine Particle Concentrations in 2030

    Science.gov (United States)

    Liousse, C.; Roblou, L.; Assamoi, E.; Criqui, P.; Galy-Lacaux, C.; Rosset, R.

    2014-12-01

    Fossil fuel (traffic, industries) and biofuel (domestic fires) emissions of gases and particles in Africa are expected to significantly increase in the near future, particularly due to rapid growth of African cities and megacities. In this study, we will present the most recent developments of African combustion emission inventories, including African specificities. Indeed, a regional fossil fuel and biofuel inventory for gases and particulates described in Liousse et al. (2014) has been developed for Africa at a resolution of 0.25° x 0.25° for the years 2005 and 2030. For 2005, the original database of Junker and Liousse (2008) was used after modification for updated regional fuel consumption and emission factors. Two prospective inventories for 2030 are derived based on Prospective Outlook on Long-term Energy Systems (POLES) model (Criqui, 2001). The first is a reference scenario (2030ref) with no emission controls and the second is for a "clean" scenario (2030ccc*) including Kyoto policy and African specific emission control. This inventory predicts very large increases of pollutant emissions in 2030 (e.g. contributing to 50% of global anthropogenic organic particles), if no emission regulations are implemented. These inventories have been introduced in RegCM4 model. In this paper we will focus on aerosol modelled concentrations in 2005, 2030ref and 2030ccc*. Spatial distribution of aerosol concentrations will be presented with a zoom at a few urban and rural sites. Finally mortality rates (respiratory, cardiovascular) caused by anthropogenic PM2.5 increase from 2005 to 2030, calculated following Lelieveld et al. (2013), will be shown for each scenarios. To conclude, this paper will discuss the effectiveness of scenarios to reduce emissions, aerosol concentrations and mortality rates, underlining the need for further measurements scheduled in the frame of the new DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions) program.

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

    OpenAIRE

    Nitri Arinda; Emil Budianto; Helmiyati

    2009-01-01

    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 exp...

  9. 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

  10. Turbulent Concentration of mm-Size Particles in the Protoplanetary Nebula: Scale-Dependent Cascades

    Science.gov (United States)

    Cuzzi, J. N.; Hartlep, T.

    2015-01-01

    The initial accretion of primitive bodies (here, asteroids in particular) from freely-floating nebula particles remains problematic. Traditional growth-by-sticking models encounter a formidable "meter-size barrier" (or even a mm-to-cm-size barrier) in turbulent nebulae, making the preconditions for so-called "streaming instabilities" difficult to achieve even for so-called "lucky" particles. Even if growth by sticking could somehow breach the meter size barrier, turbulent nebulae present further obstacles through the 1-10km size range. On the other hand, nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids. Theoretical understanding of nebula turbulence is itself in flux; recent models of MRI (magnetically-driven) turbulence favor low-or- no-turbulence environments, but purely hydrodynamic turbulence is making a comeback, with two recently discovered mechanisms generating robust turbulence which do not rely on magnetic fields at all. An important clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids; scenarios leading directly from independent nebula particulates to large objects of this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios. 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. There is evidence that at least the ordinary chondrite parent bodies were initially composed entirely of a homogeneous mix of such particles. Thus, while they are arcane, turbulent concentration models acting directly on chondrule size particles are worthy of deeper study. The typical sizes of planetesimals and the rate of their formation can be

  11. 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

  12. 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; 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, A.K.; 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; 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, A.B.; 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; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Patrick Aaron; Scott, Rebecca; Segato, Gianfranco; Selyuzhenkov, Ilya; Senyukov, Serhiy; Seo, Jeewon; Serci, Sergio; Serradilla, Eulogio; Sevcenco, Adrian; Sgura, Irene; Shabetai, Alexandre; Shabratova, Galina; Shahoyan, Ruben; Sharma, Natasha; Sharma, Satish; Shigaki, Kenta; Shimomura, Maya; Shtejer, Katherin; Sibiriak, Yury; Siciliano, Melinda; Sicking, Eva; Siddhanta, Sabyasachi; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Sinha, Bikash; Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Skjerdal, Kyrre; Smakal, Radek; Smirnov, Nikolai; Snellings, Raimond; Sogaard, Carsten; Soltz, Ron Ariel; Son, Hyungsuk; Song, Jihye; Song, Myunggeun; Soos, Csaba; Soramel, Francesca; Sputowska, Iwona; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Stefanini, Giorgio; 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; 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; Øvrebekk, 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 ...

  13. The effect of concentration of glycerol and electric current on the morphology and particle size of electrodeposited cadmium powder

    Directory of Open Access Journals (Sweden)

    S. G. Viswanath

    2013-06-01

    Full Text Available Cadmium powder was obtained by electrodeposition of cadmium from glycerol and sulphuric acid. The morphology and particle size of these powders were studied. Broken dendrites, intermingled with spongy and irregular particles were observed in the powder. Around 60% of particles were below 100 µm. XRD studies showed that particles with sizes between 212.2 and 303.2 nm were present in the powder. The apparent density of cadmium powder decreased with increase in concentration of glycerol. The stability of the powder and current efficiency were also studied

  14. Proteinuria increases oxylipid concentrations in VLDL and HDL but not LDL particles in the rat.

    Science.gov (United States)

    Newman, John W; Kaysen, George A; Hammock, Bruce D; Shearer, Gregory C

    2007-08-01

    We previously established that proteinuria alters the apolipoprotein content of lipoproteins. This study was conducted to establish whether proteinuria also alters the concentrations of oxidized lipids within lipoprotein density fractions. To this end, we induced passive Heymann nephritis in Sprague Dawley rats and measured an array of alkaline-stable oxylipids in VLDL, LDL, and HDL particles. Proteinuria increased the total oxylipid amounts in the HDL and VLDL fractions. More importantly, these levels were increased when expressed per unit lipoprotein protein, indicating that the oxidized lipid load per particle was increased. Epoxides and diols increased approximately 2-fold in HDL and approximately 5-fold in VLDL, whereas LDL showed approximately 2-fold decreases. The hydroxyeicosatetraenoic acids and hydroxyoctadecadienoic acids (HODEs) increased >4-fold in HDL and >20-fold in VLDL, whereas LDL showed approximately 2-fold decreases in the HODEs. Therefore, nephrotic syndrome alters the lipoprotein oxylipid composition independently of an increase in total lipoprotein levels. These proteinuria-induced changes may be associated with the cardiovascular risk of lipoprotein oxidation.

  15. 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.

  16. 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.

  17. 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

    Indoor and outdoor particle size distributions, indoor-outdoor pressure difference, indoor air-exchange rate, and meteorological conditions were measured at an uninhabited apartment located in a busy street in Copenhagen during 1-month long fall, winter and spring campaigns. Particle penetration...... predicted well the indoor concentration of coarse (1.2-4 mum) particles of outdoor origin for the fall and spring campaign. The model performed less well for the fine (0.5-1.2 mum) particle concentration and the winter campaign. The association between the ratio measured/predicted indoor concentration...... and factors not included in the deterministic model was analysed statistically and the result was used to determine a correction factor to the model prediction. The correction factor was found to depend on wind velocity, outdoor relative humidity, and air exchange rate. Including the correction factor reduced...

  18. 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.

  19. 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.

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

    DEFF Research Database (Denmark)

    Lauros, J.; Sogachev, Andrey; Smolander, S.

    2010-01-01

    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....

  1. 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.

  2. Particles fluidized bed receiver/reactor tests with quartz sand particles using a 100-kWth beam-down solar concentrating system at Miyazaki

    Science.gov (United States)

    Kodama, Tatsuya; Gokon, Nobuyuki; Cho, Hyun Seok; Matsubara, Koji; Kaneko, Hiroshi; Senuma, Kazuya; Itoh, Sumie; Yokota, Shin-nosuke

    2017-06-01

    A window-type, solar fluidized bed receiver with quartz sand particles was tested by a 100-kWth novel beam-down solar concentrating system at Miyazaki, Japan. A compound parabolic concentrator (CPC) was placed above the quartz window of the receiver to increase the concentration of the solar fluxes from the beam-down solar concentrating system. The solar tests were performed in the middle of December, 2015. The central bed temperature of the receiver was reached around 960-1100° C. It was found that only 20 Ndm3/min of air flow rate was enough to create the uniform fluidization of the particles at the given temperature range. It was predicted that if the central bed temperature could have been higher than 1100°C if solar receiver test had conducted in other seasons than winter. The next solar campaign of the receiver test will be carried out in October, 2016.

  3. 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

  4. 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)

    Hofmann, Martin Alexander

    2012-01-01

    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, θ 13 , has only recently been found, amongst others by the reactor antineutrino disappearance experiment Double Chooz. This experiment detects anti ν 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 ∝ 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

  5. 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

  6. SU-E-I-83: Detectability Limits of a New Positron Emission Mammography in Relation to Tumour-Size, Tumour-To-Background Ratio and Activity Concentration.

    Science.gov (United States)

    Gonzalez, A Vicedo; Hernández, T García; Granero, D; Gonzalez, L Brualla; Ferrando, J Rosello; Sanchez, R; Ferrer, J

    2012-06-01

    Positron emission mammography (PEM) improves spatial resolution and sensitivity, making it suitable for early breast tumours detection. The aim of this study is to evaluate the limits of a dedicated breast PET in terms of tumour-size, tumour-to-background activity concentration ratio (TBR) and activity concentration. A dedicated PEM is evaluated. To characterize the device, we use a phantom of 15 cm of diameter containing 6 inserts of inner diameters 18, 15, 11, 8, 5 and 3 mm. To evaluate the detectability limits images are acquired by varying the TBR from 10 to 2 and without background activity concentration. In all the studies the activity concentration for the 6 inserts is the same (3.7 kBq/ml). To asses the activity concentration limit, the SBR is maintained fixed and acquisitions at different times are performed. When there is not background, all the inserts are visible in the PEM. Increasing the background decreases the detectability. With a SBR of 10, the smaller insert is still visible. For TBR between 10, inserts >= 5 mm can be seen With a TBR of 2, only inserts with a diameter higher than 5 mm are visible. When the TBR is fixed, decreasing the activity concentration, decreases the capability of detectability. The results suggest that PEM can be used for diagnosis of small lesions when TBR is higher than 2. Further clinical studies need to be carried out in order to validate these results. © 2012 American Association of Physicists in Medicine.

  7. Effect of particle concentration on the microstructural and macromechanical properties of biocompatible magnetic hydrogels.

    Science.gov (United States)

    Bonhome-Espinosa, A B; Campos, F; Rodriguez, I A; Carriel, V; Marins, J A; Zubarev, A; Duran, J D G; Lopez-Lopez, M T

    2017-04-19

    We analyze the effect of nanoparticle concentration on the physical properties of magnetic hydrogels consisting of polymer networks of the human fibrin biopolymer with embedded magnetic particles, swollen by a water-based solution. We prepared these magnetic hydrogels by polymerization of mixtures consisting mainly of human plasma and magnetic nanoparticles with OH - functionalization. Microscopic observations revealed that magnetic hydrogels presented some cluster-like knots that were connected by several fibrin threads. By contrast, nonmagnetic hydrogels presented a homogeneous net-like structure with only individual connections between pairs of fibers. The rheological analysis demonstrated that the rigidity modulus, as well as the viscoelastic moduli, increased quadratically with nanoparticle content following a square-like function. Furthermore, we found that time for gel point was shorter in the presence of magnetic nanoparticles. Thus, we can conclude that nanoparticles favor the cross-linking process, serving as nucleation sites for the attachment of the fibrin polymer. Attraction between the positive groups of the fibrinogen, from which the fibrin is polymerized, and the negative OH - groups of the magnetic particle surface qualitatively justifies the positive role of the nanoparticles in the enhancement of the mechanical properties of the magnetic hydrogels. Indeed, we developed a theoretical model that semiquantitatively explains the experimental results by assuming the indirect attraction of the fibrinogen through the attached nanoparticles. Due to this attraction the monomers condense into nuclei of the dense phase and by the end of the polymerization process the nuclei (knots) of the dense phase cross-link the fibrin threads, which enhances their mechanical properties.

  8. Concentration-dependent systemic response after inhalation of nano-sized zinc oxide particles in human volunteers.

    Science.gov (United States)

    Monsé, Christian; Hagemeyer, Olaf; Raulf, Monika; Jettkant, Birger; van Kampen, Vera; Kendzia, Benjamin; Gering, Vitali; Kappert, Günther; Weiss, Tobias; Ulrich, Nadin; Marek, Eike-Maximilian; Bünger, Jürgen; Brüning, Thomas; Merget, Rolf

    2018-02-12

    Inhalation of high concentrations of zinc oxide particles (ZnO) may cause metal fume fever. In an earlier human inhalation study, no effects were observed after exposure to ZnO concentrations of 0.5 mg/m 3 . Further data from experimental studies with pure ZnO in the concentration range between 0.5 and 2.5 mg/m 3 are not available. It was the aim of this experimental study to establish the concentration-response relationship of pure nano-sized ZnO particles. Sixteen healthy subjects were exposed to filtered air and ZnO particles (0.5, 1.0 and 2.0 mg/m 3 ) for 4 h on 4 different days, including 2 h of cycling with a low workload. The effects were assessed before, immediately after, and about 24 h after each exposure. Effect parameters were symptoms, body temperature, inflammatory markers and clotting factors in blood, and lung function. Concentration-dependent increases in symptoms, body temperature, acute phase proteins and neutrophils in blood were detected after ZnO inhalation. Significant effects were detected with ZnO concentrations of 1.0 mg/m 3 or higher, with the most sensitive parameters being inflammatory markers in blood. A concentration-response relationship with nano-sized ZnO particles in a low concentration range was demonstrated. Systemic inflammatory effects of inhaled nano-sized ZnO particles were observed at concentrations well below the occpational exposure limit for ZnO in many countries. It is recommended to reassess the exposure limit for ZnO at workplaces.

  9. A Study of a Powder Coating Gun Near Field: Particle Flow in an Isothermal Staggered Concentric Air Jet

    Directory of Open Access Journals (Sweden)

    Graham Payne

    2014-07-01

    Full Text Available An experimental study of inert particle dispersion in an isothermal concentric air jet near field was conducted for cases of standard non-staggered and alternative staggered jet nozzles, each taken from a polymer powder flame deposition gun. The experimental work consisted of analysis of high speed digital images of the inert two phase isothermal jet flow, illuminated by a laser light sheet along and across the jet axis. The analysis of particle spread in the jet, represented by families of particle density distributions, clearly showed that the staggered nozzles resulted in a better-focused flow, with narrower distributions in the near field, and in the elimination of the recirculation zone that disrupted the particle flow in a non-staggered nozzle arrangement. In all cases, histograms of the cross-sectional particle area density were found to be approximately Gaussian. It was also found that there was a wide variation in the size and shape of the ground polymer particles used and these two characteristics caused a wide variation in the radial and axial velocities of the particles. Despite the differences between single-phase numerical simulations and experimental results, reported in Payne et al. [1], the introduction of particles into a numerical model produced satisfactory agreement with the particle velocities found experimentally.

  10. Spatial distribution of ground-level urban background O3 concentrations in the Metropolitan Area of Buenos Aires, Argentina

    International Nuclear Information System (INIS)

    Pineda Rojas, Andrea L.; Venegas, Laura E.

    2013-01-01

    In this work, a recently developed urban-scale atmospheric dispersion model (DAUMOD-GRS) is applied to evaluate the ground-level ozone (O 3 ) concentrations resulting from anthropogenic area sources of NO x and VOC in the Metropolitan Area of Buenos Aires (MABA). The statistical comparison of model results with observations (including new available data from seventeen sites) shows a good model performance. Estimated summer highest diurnal O 3 1-h concentrations in the MABA vary between 15 ppb in the most urbanised area and 53 ppb in the suburbs. All values are below the air quality standard. Several runs are performed to evaluate the impact of possible future emission reductions on O 3 concentrations. Under all hypothetical scenarios, the maximum diurnal O 3 1-h concentration obtained for the area is slightly reduced (up to 4%). However, maximum diurnal O 3 concentrations could increase at some less urbanised areas of MABA depending on the relative reductions of the emissions of NO x and VOC. -- Highlights: ► A recently developed air quality model reproduces well observed O 3 levels in MABA. ► Modelled summer maximum diurnal O 3 concentrations vary in the area between 15 and 53 ppb. ► All hourly values are below the air quality standard (120 ppb). ► Possible future emission reductions would have small impact on the highest level. -- The distribution of summer maximum diurnal ground-level O 3 concentrations in the Metropolitan Area of Buenos Aires is evaluated applying a recently developed simple urban air quality model

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

    DEFF Research Database (Denmark)

    Lauros, J.; Sogachev, Andrey; Smolander, S.

    2011-01-01

    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 simulated...

  12. Spatial distribution of ground-level urban background O3 concentrations in the Metropolitan Area of Buenos Aires, Argentina.

    Science.gov (United States)

    Pineda Rojas, Andrea L; Venegas, Laura E

    2013-12-01

    In this work, a recently developed urban-scale atmospheric dispersion model (DAUMOD-GRS) is applied to evaluate the ground-level ozone (O3) concentrations resulting from anthropogenic area sources of NOx and VOC in the Metropolitan Area of Buenos Aires (MABA). The statistical comparison of model results with observations (including new available data from seventeen sites) shows a good model performance. Estimated summer highest diurnal O3 1-h concentrations in the MABA vary between 15 ppb in the most urbanised area and 53 ppb in the suburbs. All values are below the air quality standard. Several runs are performed to evaluate the impact of possible future emission reductions on O3 concentrations. Under all hypothetical scenarios, the maximum diurnal O3 1-h concentration obtained for the area is slightly reduced (up to 4%). However, maximum diurnal O3 concentrations could increase at some less urbanised areas of MABA depending on the relative reductions of the emissions of NOx and VOC. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Omega-3 PUFA concentration by a novel PVDF nano-composite membrane filled with nano-porous silica particles.

    Science.gov (United States)

    Ghasemian, Samaneh; Sahari, Mohammad Ali; Barzegar, Mohsen; Ahmadi Gavlighi, Hasan

    2017-09-01

    In this study, polyvinylidene fluoride (PVDF) and nano-porous silica particle were used to fabricate an asymmetric nano-composite membrane. Silica particles enhanced the thermal stability of PVDF/SiO 2 membranes; increasing the decomposition temperature from 371°C to 408°C. Cross sectional morphology showed that silica particles were dispersed in polymer matrix uniformly. However, particle agglomeration was found at higher loading of silica (i.e., 20 by weight%). The separation performance of nano-composite membranes was also evaluated using the omega-3 polyunsaturated fatty acids (PUFA) concentration at a temperature and pressure of 30°C and 4bar, respectively. Silica particle increased the omega-3PUFA concentration from 34.8 by weight% in neat PVDF to 53.9 by weight% in PVDF with 15 by weight% of silica. Moreover, PVDF/SiO 2 nano-composite membranes exhibited enhanced anti-fouling property compared to neat PVDF membrane. Fouling mechanism analysis revealed that complete pore blocking was the predominant mechanism occurring in oil filtration. The concentration of omega-3 polyunsaturated fatty acids (PUFA) is important in the oil industries. While the current methods demand high energy consumptions in concentrating the omega-3, membrane separation technology offers noticeable advantages in producing pure omega-3 PUFA. Moreover, concentrating omega-3 via membrane separation produces products in the triacylglycerol form which possess better oxidative stability. In this work, the detailed mechanisms of fouling which limits the performance of membrane separation were investigated. Incorporating silica particles to polymeric membrane resulted in the formation of mixed matrix membrane with improved anti-fouling behaviour compared to the neat polymeric membrane. Hence, the industrial potential of membrane processing to concentrate omega-3 fatty acids is enhanced. Copyright © 2017. Published by Elsevier Ltd.

  14. Comparison of sp-ICP-MS and MDG-ICP-MS for the determination of particle number concentration.

    Science.gov (United States)

    Gschwind, Sabrina; Aja Montes, Maria de Lourdes; Günther, Detlef

    2015-05-01

    In 2011, the European Commission introduced new regulations on how nanomaterials are defined. Since then, researchers have emphasized that more complete characterization of nanoparticles (NPs) includes not just mass and size determinations, but also the determination of the particle number concentrations. In this study, two different sample introduction approaches for the analysis of NP suspensions with inductively coupled plasma mass spectrometry (ICP-MS) were investigated: pneumatic nebulization (sp-ICP-MS) and microdroplet generation (MDG-ICP-MS). These approaches were compared for the determination of particle number concentrations (PNCs) of gold and silver NP suspensions diluted in either ultra-pure water or citrate solution. For accurate sp-ICP-MS analysis, it is crucial to know the transport efficiency of nebulized sample into the plasma. Here, transport efficiencies, measured by the waste collection method, were 11-14 % for Ag suspensions and 9-11 % for Au. In contrast, the droplet transport efficiency of MDG-ICP-MS was 100 %. Analysis by sp-ICP-MS yielded a lower particle number concentration than expected (only 20-40 % of the expected value), whereas MDG-ICP-MS had NP recoveries up to 80 %. This study indicates that NP reference materials are of major importance for particle number determination and detailed results on particle number concentrations for different suspensions with respect to storage time are discussed.

  15. A model and diagnostic measures for response time series on tests of concentration: Historical background, conceptual framework, and some applications

    NARCIS (Netherlands)

    Breukelen, G.J.P. van; Roskam, E.E.C.I.; Eling, P.A.T.M.; Jansen, R.W.T.L.; Souren, D.A.P.B.; Ickenroth, J.G.M.

    1995-01-01

    Based upon classical hypotheses about accumulating mental fatigue and distraction and its effect on response times, put forward in late 19th and early 20th century papers, a mathematical model is proposed for response times on tests of speed and concentration. The model assumes the random occurrence

  16. 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.

  17. LA-ICP-MS of rare earth elements concentrated in cation-exchange resin particles for origin attribution of uranium ore concentrate.

    Science.gov (United States)

    Asai, Shiho; Limbeck, Andreas

    2015-04-01

    Rare earth elements (REE) concentrated on cation-exchange resin particles were measured with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to obtain chondrite-normalized REE plots. The sensitivity of REE increased in ascending order of the atomic number, according to the sensitivity trend in pneumatic nebulization ICP-MS (PN-ICP-MS). The signal intensities of REE were nearly proportional to the concentrations of REE in the immersion solution used for particle-preparation. Minimum measurable concentration calculated from the net signals of REE was approximately 1 ng/g corresponding to 0.1 ng in the particle-preparation solution. In LA analysis, formation of oxide and hydroxide of the light REE and Ba which causes spectral interferences in the heavy REE measurement was effectively attenuated due to the solvent-free measurement capability, compared to conventional PN-ICP-MS. To evaluate the applicability of the proposed method, the REE-adsorbed particles prepared by immersing them in a U-bearing solution (commercially available U standard solution) were measured with LA-ICP-MS. Aside from the LA analysis, each concentration of REE in the same U standard solution was determined with conventional PN-ICP-MS after separating REE by cation-exchange chromatography. The concentrations of REE were ranging from 0.04 (Pr) to 1.08 (Dy) μg/g-U. The chondrite-normalized plot obtained through LA-ICP-MS analysis of the U standard sample exhibited close agreement with that obtained through the PN-ICP-MS of the REE-separated solution within the uncertainties. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Simulated tritium concentrations in river waters of the western Lake Taupo catchment, New Zealand with MODPATH particle tracking

    Science.gov (United States)

    Gusyev, M. A.; Abrams, D.; Toews, M. W.; Morgenstern, U.; Stewart, M. K.

    2014-03-01

    We simulated in a previous study tritium concentrations in the river waters of the western Lake Taupo catchment (WLTC) using MODFLOW/MT3DMS model (Gusyev et al., 2013). The model was calibrated to match simulated tritium to measured tritium in river waters at baseflows of the Waihaha, Whanganui, Whareroa, Kuratau and Omori river catchments of the WLTC. Following from this work we now utilized the same MODFLOW model for the WLTC to calculate the pathways of groundwater particles (and their corresponding tritium concentrations) using steady-state particle tracking with MODPATH. In order to simulate baseflow tritium concentrations with MODPATH, transit time distributions (TTDs) such as cumulative frequency distribution (CFD) and probability density function (PDF) are generated with particle tracking for the river networks of the five WLTC catchment outflows. Then, PDFs are used in the convolution integral with tritium concentration time series obtained in the precipitation. The resulting MODPATH tritium concentrations yield a very good match to measured tritium concentrations and are similar to the MT3DMS simulated tritium concentrations, with the greatest variation occurring around the bomb peak. MODPATH and MT3DMS also yield similar Mean Transit Times (MTT) of groundwater contribution to river baseflows, but the actual shape of the TTDs is strikingly different. While both distributions provide valuable information, the methodologies used to derive the TTDs are fundamentally different and hence must be interpreted differently. With the current models setting, only the methodology used with MODPATH provides the true TTD for use with the convolution integral.

  19. Estimating representative background PM2.5 concentration in heavily polluted areas using baseline separation technique and chemical mass balance model

    Science.gov (United States)

    Gao, Shuang; Yang, Wen; Zhang, Hui; Sun, Yanling; Mao, Jian; Ma, Zhenxing; Cong, Zhiyuan; Zhang, Xian; Tian, Shasha; Azzi, Merched; Chen, Li; Bai, Zhipeng

    2018-02-01

    The determination of background concentration of PM2.5 is important to understand the contribution of local emission sources to total PM2.5 concentration. The purpose of this study was to exam the performance of baseline separation techniques to estimate PM2.5 background concentration. Five separation methods, which included recursive digital filters (Lyne-Hollick, one-parameter algorithm, and Boughton two-parameter algorithm), sliding interval and smoothed minima, were applied to one-year PM2.5 time-series data in two heavily polluted cities, Tianjin and Jinan. To obtain the proper filter parameters and recession constants for the separation techniques, we conducted regression analysis at a background site during the emission reduction period enforced by the Government for the 2014 Asia-Pacific Economic Cooperation (APEC) meeting in Beijing. Background concentrations in Tianjin and Jinan were then estimated by applying the determined filter parameters and recession constants. The chemical mass balance (CMB) model was also applied to ascertain the effectiveness of the new approach. Our results showed that the contribution of background PM concentration to ambient pollution was at a comparable level to the contribution obtained from the previous study. The best performance was achieved using the Boughton two-parameter algorithm. The background concentrations were estimated at (27 ± 2) μg/m3 for the whole year, (34 ± 4) μg/m3 for the heating period (winter), (21 ± 2) μg/m3 for the non-heating period (summer), and (25 ± 2) μg/m3 for the sandstorm period in Tianjin. The corresponding values in Jinan were (30 ± 3) μg/m3, (40 ± 4) μg/m3, (24 ± 5) μg/m3, and (26 ± 2) μg/m3, respectively. The study revealed that these baseline separation techniques are valid for estimating levels of PM2.5 air pollution, and that our proposed method has great potential for estimating the background level of other air pollutants.

  20. Particle concentrating and sorting under a rotating electric field by direct optical-liquid heating in a microfluidics chip.

    Science.gov (United States)

    Chen, Yu-Liang; Jiang, Hong-Ren

    2017-05-01

    We demonstrate a functional rotating electrothermal technique for rapidly concentrating and sorting a large number of particles on a microchip by the combination of particle dielectrophoresis (DEP) and inward rotating electrothermal (RET) flows. Different kinds of particles can be attracted (positive DEP) to or repelled (negative DEP) from electrode edges, and then the n-DEP responsive particles are further concentrated in the heated region by RET flows. The RET flows arise from the spatial inhomogeneous electric properties of fluid caused by direct infrared laser (1470 nm) heating of solution in a rotating electric field. The direction of the RET flows is radially inward to the heated region with a co-field (the same as the rotating electric field) rotation. Moreover, the velocity of the RET flows is proportional to the laser power and the square of the electric field strength. The RET flows are significant over a frequency range from 200 kHz to 5 MHz. The RET flows are generated by the simultaneous application of the infrared laser and the rotating electric field. Therefore, the location of particle concentrating can be controlled within the rotating electric field depending on the position of the laser spot. This multi-field technique can be operated in salt solutions and at higher frequency without external flow pressure, and thus it can avoid electrokinetic phenomena at low frequency to improve the manipulation accuracy for lab-on-chip applications.

  1. Calculation of concentration fields of high-inertia aerosol particles in the flow past a cylindrical fibre

    Science.gov (United States)

    Zaripov, T. S.; Gilfanov, A. K.; Zaripov, S. K.; Rybdylova, O. D.; Sazhin, S. S.

    2018-01-01

    The behaviour of high-inertia aerosol particles’ concentration fields in stationary gas suspension flows around a cylinder is investigated using a numerical solution to the Navier-Stokes equations and the fully Lagrangian approach for four Stokes numbers (Stk = 0.1, 1, 4, 10) and three Reynolds numbers (Re = 1, 10, 100). It has been shown that the points of maximum particle concentration along each trajectory shift downstream both when Stk and/or Re increase.

  2. Physicochemical characterization of Capstone depleted uranium aerosols I: uranium concentration in aerosols as a function of time and particle size.

    Science.gov (United States)

    Parkhurst, Mary Ann; Cheng, Yung Sung; Kenoyer, Judson L; Traub, Richard J

    2009-03-01

    During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing DU were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time, particularly within the first minute after a shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s after perforation, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% after 30 min. The initial and maximum uranium concentrations were lower in the Bradley vehicle than those observed in the Abrams tank, and the concentration levels decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in a cyclone sampler, which collected aerosol continuously for 2 h after perforation. The percentages of uranium mass in the cyclone separator stages ranged from 38 to 72% for the Abrams tank with conventional armor. In most cases, it varied with particle size, typically with less uranium associated with the smaller particle sizes. Neither the Abrams tank with DU armor nor the Bradley vehicle results were specifically correlated with particle size and can best be represented by their average uranium mass concentrations of 65

  3. Fluorescent biological aerosol particle concentrations and size distributions measured with an Ultraviolet Aerodynamic Particle Sizer (UV-APS in Central Europe

    Directory of Open Access Journals (Sweden)

    J. A. Huffman

    2010-04-01

    Full Text Available Primary Biological Aerosol Particles (PBAPs, including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany we used an Ultraviolet Aerodynamic Particle Sizer (UV-APS to measure Fluorescent Biological Aerosol Particles (FBAPs, which provide an estimate of viable bioaerosol particles and can be regarded as an approximate lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (<1 μm, but not for coarse particles (1–20 μm.

    Averaged over the four-month measurement period (August–December 2006, the mean number concentration of coarse FBAPs was ~3×10−2 cm−3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1μg m−3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10−2 cm−3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle (24-h with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be single bacterial cells, larger fungal spores, and pollen grains, respectively.

    The observed number

  4. 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.

  5. Characterization of fluidization regime in circulating fluidized bed reactor with high solid particle concentration using computational fluid dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Chalermsinsuwan, Benjapon; Thummakul, Theeranan; Piumsomboon, Pornpote [Chulalongkorn University, Bangkok (Thailand); Gidaspow, Dimitri [Armour College of Engineering, Chicago (United States)

    2014-02-15

    The hydrodynamics inside a high solid particle concentration circulating fluidized bed reactor was investigated using computational fluid dynamics simulation. Compared to a low solid particle reactor, all the conventional fluidization regimes were observed. In addition, two unconventional fluidization regimes, circulating-turbulent and dense suspension bypassing regimes, were found with only primary gas injection. The circulating-turbulent fluidization regime showed uniformly dense solid particle distribution in all the system directions, while the dense suspension bypassing fluidization regime exhibited the flow of solid particles at only one side system wall. Then, comprehensive fluidization regime clarification and mapping were evaluated using in-depth system parameters. In the circulating-turbulent fluidization regime, the total granular temperature was low compared to the adjacent fluidization regimes. In the dense suspension bypassing fluidization regime, the highest total granular temperature was obtained. The circulating-turbulent and dense suspension bypassing fluidization regimes are suitable for sorption and transportation applications, respectively.

  6. Estimating background denudation rates and delivery of landslide sediment from a time series of 10Be concentrations in landslide dominated basins in the southern Central Range of Taiwan

    Science.gov (United States)

    Chen, C. Y.; Willett, S.; West, A. J.; Dadson, S. J.; Hovius, N.; Christl, M.; Shyu, J. B. H.

    2017-12-01

    The southern Central Range of Taiwan is located at a tectonic transition zone between an oceanic subduction zone and the arc-continent collision forming the Taiwan orogen. The rapidly evolving tectonic setting, tropical climate and frequent typhoons result in a complex uplift pattern, transient landscapes and extensive landslides. For this study, we obtained a series of 10Be concentrations over the last decade for 13 major drainage basins in the southern Central Range, bracketing the occurrence of a major typhoon, Morakot, which hit Taiwan in 2009 and triggered thousands of landslides. This time series allows us to simultaneously estimate the background erosion rate and assess the impact of Morakot-triggered landslides on 10Be concentrations. The time series of 10Be concentrations shows temporally lower concentrations of 10Be indicating dilution following the Morakot event in most basins. The diluted 10Be concentrations imply erosion rates up to three times higher than the lowest measured rates in the same basins. We constructed a simple sediment-mixing model parameterized by a sudden input of sediment supplied from landslides superimposed on a background denudation rate. This model was calibrated to measured landslide inventories and the series of 10Be data. We obtain a range of permissible background erosion rate and fraction of landslide sediments over time for each basin. The inferred background erosion rate reveals a northward increasing trend, reflecting the initial stage of the mountain building and indicating tectonic forcing is the main driver of the landscape evolution in the southern Central Range. The temporal changes in fraction of landslide sediments show that the available landslide material generated by the Morakot event is decreasing over time with a timescale of several years.

  7. Association between the concentration of fine particles in the atmosphere and acute respiratory diseases in children.

    Science.gov (United States)

    Nascimento, Antônio Paula; Santos, Jane Meri; Mill, José Geraldo; Souza, Juliana Bottoni de; Reis, Neyval Costa; Reisen, Valdério Anselmo

    2017-01-12

    To analyze the association between fine particulate matter concentration in the atmosphere and hospital care by acute respiratory diseases in children. Ecological study, carried out in the region of Grande Vitória, Espírito Santo, in the winter (June 21 to September 21, 2013) and summer (December 21, 2013 to March 19, 2014). We assessed data of daily count for outpatient care and hospitalization by respiratory diseases (ICD-10) in children from zero to 12 years in three hospitals in the Region of Grande Vitória. For collecting fine particulate matter, we used portable samplers of particles installed in six locations in the studied region. The Generalized Additive Model with Poisson distribution, fitted for the effects of predictor covariates, was used to evaluate the relationship between respiratory outcomes and concentration of fine particulate matter. The increase of 4.2 µg/m3 (interquartile range) in the concentration of fine particulate matter increased in 3.8% and 5.6% the risk of medical care or hospitalization, respectively, on the same day and with six-day lag from the exposure. We identified positive association between outpatient care and hospitalizations of children under 12 years due to acute respiratory diseases and the concentration of fine particulate matter in the atmosphere. Analisar a associação entre a concentração de material particulado fino na atmosfera e atendimento hospitalar por doenças respiratórias agudas em crianças. Estudo ecológico, realizado na Região da Grande Vitória, ES, no inverno (21 de junho a 21 de setembro de 2013) e no verão (21 de dezembro de 2013 a 19 de março de 2014). Foram avaliados dados de contagem diária de atendimentos ambulatoriais e hospitalizações por doenças respiratórias (CID-10) em crianças de zero a 12 anos em três hospitais da Região da Grande Vitoria. Para a coleta de material particulado fino foram utilizados amostradores portáteis de partículas instalados em seis locais na regi

  8. Total and size-resolved particle number and black carbon concentrations in urban areas near Schiphol airport (the Netherlands)

    NARCIS (Netherlands)

    Keuken, M.P.; Moerman, M.; Zandveld, P.; Henzing, J.S.; Hoek, G.

    2015-01-01

    The presence of black carbon, and size-resolved and total particle number concentrations (PNC) were investigated in the vicinity of Schiphol airport in the Netherlands, the fourth busiest airport in Europe. Continuous measurements were conducted between March and May 2014at Adamse Bos, located 7km

  9. Continuous measurement of number concentrations and elemental composition of aerosol particles for a dust storm event in Beijing

    Science.gov (United States)

    Zhang, Renjian; Han, Zhiwei; Shen, Zhenxing; Cao, Junji

    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 (>2 μm) increased more significantly than fine particles (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, 251.8 μg 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.

  10. Heavy metal concentrations in particle size fractions from street dust of Murcia (Spain) as the basis for risk assessment.

    Science.gov (United States)

    Acosta, Jose A; Faz, Ángel; Kalbitz, Karsten; Jansen, Boris; Martínez-Martínez, Silvia

    2011-11-01

    Street dust has been sampled from six different types of land use of the city of Murcia (Spain). The samples were fractionated into eleven particle size fractions (<2, 2-10, 10-20, 20-50, 50-75, 75-106, 106-150, 150-180, 180-425, 425-850 μm and 850-2000 μm) and analyzed for Pb, Cu, Zn and Cd. The concentrations of these four potentially toxic metals were assessed, as well as the effect of particle size on their distribution. A severe enrichment of all metals was observed for all land-uses (industrial, suburban, urban and highways), with the concentration of all metals affected by the type of land-use. Coarse and fine particles in all cases showed concentrations of metals higher than those found in undisturbed areas. However, the results indicated a preferential partitioning of metals in fine particle size fractions in all cases, following a logarithmic distribution. The accumulation in the fine fractions was higher when the metals had an anthropogenic origin. The strong overrepresentation of metals in particles <10 μm indicates that if the finest fractions are removed by a vacuum-assisted dry sweeper or a regenerative-air sweeper the risk of metal dispersion and its consequent risk for humans will be highly reduced. Therefore, we recommend that risk assessment programs include monitoring of metal concentrations in dust where each land-use is separately evaluated. The finest particle fractions should be examined explicitly in order to apply the most efficient measures for reducing the risk of inhalation and ingestion of dust for humans and risk for the environment.

  11. QUALITY CONTROL OF SEMI-CONTINUOUS MOBILITY SIZE-FRACTIONATED PARTICLE NUMBER CONCENTRATION DATA. (R827352)

    Science.gov (United States)

    Fine and ultrafine particles have been postulated to play an important role in the association between ambient particulate matters and adverse health effects. As part of the EPA Supersite Program, the Southern California Particle Center & Supersite has conducted a series o...

  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...

  13. 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 Antiretroviral Therapy" trial....

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

    Science.gov (United States)

    Tada-Oikawa, Saeko; Ichihara, Gaku; Fukatsu, Hitomi; Shimanuki, Yuka; Tanaka, Natsuki; Watanabe, Eri; Suzuki, Yuka; Murakami, Masahiko; Izuoka, Kiyora; Chang, Jie; Wu, Wenting; Yamada, Yoshiji; Ichihara, Sahoko

    2016-04-16

    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.

  15. Effect of traffic restriction on atmospheric particle concentrations and their size distributions in urban Lanzhou, Northwestern China.

    Science.gov (United States)

    Zhao, Suping; Yu, Ye; Liu, Na; He, Jianjun; Chen, Jinbei

    2014-02-01

    During the 2012 Lanzhou International Marathon, the local government made a significant effort to improve traffic conditions and air quality by implementing traffic restriction measures. To evaluate the direct effect of these measures on urban air quality, especially particle concentrations and their size distributions, atmospheric particle size distributions (0.5-20 microm) obtained using an aerodynamic particle sizer (model 3321, TSI, USA) in June 2012 were analyzed. It was found that the particle number, surface area and volume concentrations for size range 0.5-10 microm were (15.0 +/- 2.1) cm(-3), (11.8 +/- 2.6) microm2/cm3 and (1.9 +/- 0.6) microm2/cm3, respectively, on the traffic-restricted day (Sunday), which is 63.2%, 53.0% and 47.2% lower than those on a normal Sunday. For number and surface area concentrations, the most affected size range was 0.5-0.7 and 0.5-0.8 microm, respectively, while for volume concentration, the most affected size ranges were 0.5-0.8, 1.7-2.0 and 5.0-5.4 microm. Number and volume concentrations of particles in size range 0.5-1.0 microm correlated well with the number of non-CNG (Compressed Natural Gas) powered vehicles, while their correlation with the number of CNG-powered vehicles was very low, suggesting that reasonable urban traffic controls along with vehicle technology improvements could play an important role in improving urban air quality.

  16. 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.

  17. 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)

    Leibold, H; Wilhelm, J.G.

    1991-01-01

    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/m 3 . 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/m 3 . 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)

  18. New considerations for PM, Black Carbon and particle number concentration for air quality monitoring across different European cities

    Directory of Open Access Journals (Sweden)

    C. Reche

    2011-07-01

    this ratio was determined for the noon period. Although in central and northern Europe N and BC levels tend to vary simultaneously, not only during the traffic rush hours but also during the whole day, in urban background stations in southern Europe maximum N levels coinciding with minimum BC levels are recorded at midday in all seasons. These N maxima recorded in southern European urban background environments are attributed to midday nucleation episodes occurring when gaseous pollutants are diluted and maximum insolation and O3 levels occur. The occurrence of SO2 peaks may also contribute to the occurrence of midday nucleation bursts in specific industrial or shipping-influenced areas, although at several central European sites similar levels of SO2 are recorded without yielding nucleation episodes.

    Accordingly, it is clearly evidenced that N variability in different European urban environments is not equally influenced by the same emission sources and atmospheric processes. We conclude that N variability does not always reflect the impact of road traffic on air quality, whereas BC is a more consistent tracer of such an influence. However, N should be measured since ultrafine particles (<100 nm may have large impacts on human health.

    The combination of PM10 and BC monitoring in urban areas potentially constitutes a useful approach for air quality monitoring. BC is mostly governed by vehicle exhaust emissions, while PM10 concentrations at these sites are also governed by non-exhaust particulate emissions resuspended by traffic, by midday atmospheric dilution and by other non-traffic emissions.

  19. 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

  20. 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.

  1. Spatial variation of particle number concentration in school microscale environments and its impact on exposure assessment.

    Science.gov (United States)

    Salimi, Farhad; Mazaheri, Mandana; Clifford, Sam; Crilley, Leigh R; Laiman, Rusdin; Morawska, Lidia

    2013-05-21

    It has not yet been established whether the spatial variation of particle number concentration (PNC) within a microscale environment can have an effect on exposure estimation results. In general, the degree of spatial variation within microscale environments remains unclear, since previous studies have only focused on spatial variation within macroscale environments. The aims of this study were to determine the spatial variation of PNC within microscale school environments, in order to assess the importance of the number of monitoring sites on exposure estimation. Furthermore, this paper aims to identify which parameters have the largest influence on spatial variation as well as the relationship between those parameters and spatial variation. Air quality measurements were conducted for two consecutive weeks at each of the 25 schools across Brisbane, Australia. PNC was measured at three sites within the grounds of each school, along with the measurement of meteorological and several other air quality parameters. Traffic density was recorded for the busiest road adjacent to the school. Spatial variation at each school was quantified using coefficient of variation (CV). The portion of CV associated with instrument uncertainty was found to be 0.3, and, therefore, CV was corrected so that only noninstrument uncertainty was analyzed in the data. The median corrected CV (CVc) ranged from 0 to 0.35 across the schools, with 12 schools found to exhibit spatial variation. The study determined the number of required monitoring sites at schools with spatial variability and tested the deviation in exposure estimation arising from using only a single site. Nine schools required two measurement sites and three schools required three sites. Overall, the deviation in exposure estimation from using only one monitoring site was as much as 1 order of magnitude. The study also tested the association of spatial variation with wind speed/direction and traffic density, using partial

  2. Distribution of gaseous and particle-bound Hg concentrations at the sites representative for urban and non-urban zones of Silesia Province

    Directory of Open Access Journals (Sweden)

    Pyta Halina

    2018-01-01

    Full Text Available The basic features of the distribution of total gaseous (TGM and particle-bound mercury (PBM concentrations were determined for a five locations representative for urban (Bielsko-Biała, Lubliniec, Zabrze and rural areas (Godów, Złoty Potok of Silesia Province. Gaseous mercury concentrations were measured (1 continuously - the automatic 1h TGM measurements in Zloty Potok and Zabrze and (2 non-continuously manual 24h TGM measurements with a pre-concentration of the Hg on gold traps (Bielsko-Biała, Lubliniec, Godów. The PBM concentrations were measured non-continuously by taking PM2.5 samples. The Hg content was determined by using a CVAAS method. The highest average concentration of TGM was recorded in Zabrze (2.8ng/m3, significantly lower (2.0ng/m3 in Bielsko-Biała and in the non-urban station in Godów, the lowest concentration (<2.0 ng/m3 was observed in Lubliniec and at the regional background station in Zloty Potok. The results obtained for TGM concentrations exceeded the European average level of 1.5 ng/m3 (AirBase, 2014. The highest average PBM concentration, associated with PM2.5, was obtained in Zabrze (70pg/m3, more than 20% lower results were obtained in Bielsko-Biała and Godów, finally, the lowest one (lower by about 40% in comparison with Zabrze were obtained in Lubliniec and Złoty Potok. Moreover, an enrichment of Hg concentration in PM was observed with the increasing of the PM content, during the heating season.

  3. 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.

  4. Impact of human activities on the concentration of indoor air particles in an antarctic research station

    Directory of Open Access Journals (Sweden)

    Erica Coelho Pagel

    Full Text Available Abstract One of the main characteristics of Antarctic buildings is the fact that they are designed mostly with a focus on energy efficiency. Although human activity is a major source of pollution, indoor air quality is not a matter of significant concern during building planning. This study examines the relationship between indoor activities in an Antarctic Research Station and the size distribution of particulate matter. Real-time particle size distribution data is used in conjunction with time-activity data. The activity number ratio is calculated using the mean number of particles found in each size range during each activity divided by the average number of particles found during a period characterized by the absence of human activities. Cooking, the use of cosmetics, waste incineration and exhaust from light vehicles were responsible for significant deterioration of indoor air related to the presence of fine and ultrafine particles. Cleaning, physical exercise and the movement of people were responsible for the emission of coarse particles. This article emphasizes the importance of post-occupancy evaluation of buildings, generating results relevant to the planning and layout of new buildings, especially regarding better indoor air quality.

  5. Fluorescent bioaerosol particle, molecular tracer, and fungal spore concentrations during dry and rainy periods in a semi-arid forest

    Directory of Open Access Journals (Sweden)

    M. I. Gosselin

    2016-12-01

    Full Text Available Bioaerosols pose risks to human health and agriculture and may influence the evolution of mixed-phase clouds and the hydrological cycle on local and regional scales. The availability and reliability of methods and data on the abundance and properties of atmospheric bioaerosols, however, are rather limited. Here we analyze and compare data from different real-time ultraviolet laser/light-induced fluorescence (UV-LIF instruments with results from a culture-based spore sampler and offline molecular tracers for airborne fungal spores in a semi-arid forest in the southern Rocky Mountains of Colorado. Commercial UV-APS (ultraviolet aerodynamic particle sizer and WIBS-3 (wideband integrated bioaerosol sensor, version 3 instruments with different excitation and emission wavelengths were utilized to measure fluorescent aerosol particles (FAPs during both dry weather conditions and periods heavily influenced by rain. Seven molecular tracers of bioaerosols were quantified by analysis of total suspended particle (TSP high-volume filter samples using a high-performance anion-exchange chromatography system with pulsed amperometric detection (HPAEC-PAD. From the same measurement campaign, Huffman et al. (2013 previously reported dramatic increases in total and fluorescent particle concentrations during and immediately after rainfall and also showed a strong relationship between the concentrations of FAPs and ice nuclei (Huffman et al., 2013; Prenni et al., 2013. Here we investigate molecular tracers and show that during rainy periods the atmospheric concentrations of arabitol (35.2 ± 10.5 ng m−3 and mannitol (44.9 ± 13.8 ng m−3 were 3–4 times higher than during dry periods. During and after rain, the correlations between FAP and tracer mass concentrations were also significantly improved. Fungal spore number concentrations on the order of 104 m−3, accounting for 2–5 % of TSP mass during dry periods and 17–23 % during rainy

  6. Atmospheric concentrations and gas-particle partitioning of PCDD/Fs and dioxin-like PCBs around Hochiminh city.

    Science.gov (United States)

    Trinh, Minh Man; Tsai, Ching Lan; Hien, To Thi; Thuan, Ngo Thi; Chi, Kai Hsien; Lien, Chien Guo; Chang, Moo Been

    2018-07-01

    Atmospheric PCDD/Fs and dl-PCBs samples were collected in Hochiminh city, Vietnam to address the effect of meteorological parameters, especially rainfall, on the occurrence and gas/particle partitioning of these persistent organic pollutants. The results indicate that PCDD/Fs and dl-PCBs concentrations in industrial site are higher than those measured in commercial and rural sites during both rainy and dry seasons. In terms of mass concentration, ambient PCDD/F levels measured in dry season are significantly higher than those measured in rainy season while dl-PCB levels do not vary significantly between rainy and dry seasons. The difference could be attributed to different gas/particle partitioning characteristics between PCDD/Fs and dl-PCBs. PCDD/Fs are found to be mainly distributed in particle phase while dl- PCBs are predominantly distributed in gas phase in both rainy and dry seasons. Additionally, Junge-Pankow and Harner-Bidleman models are applied to better understand the gas/particle partitioning of these pollutants in atmosphere. As a results, both PCDD/Fs and dl-PCBs are under non-equilibrium gas/particle partitioning condition, and PCDD/Fs tend to reach equilibrium easier in rainy season while there are no clear trend for dl-PCBs. Harner-Bidleman model performs better in evaluating the gas/particle partitioning of PCDD/Fs while Junge-Pankow model results in better prediction for dl-PCBs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Source apportionment of ultrafine and fine particle concentrations in Brisbane, Australia.

    Science.gov (United States)

    Friend, Adrian J; Ayoko, Godwin A; Jayaratne, E Rohan; Jamriska, Milan; Hopke, Philip K; Morawska, Lidia

    2011-08-01

    To investigate the significance of sources around measurement sites, assist the development of control strategies for the important sources and mitigate the adverse effects of air pollution due to particle size. In this study, sampling was conducted at two sites located in urban/industrial and residential areas situated at roadsides along the Brisbane Urban Corridor. Ultrafine and fine particle measurements obtained at the two sites in June-July 2002 were analysed by positive matrix factorization. Six sources were present, including local traffic, two traffic sources, biomass burning and two currently unidentified sources. Secondary particles had a significant impact at site 1, while nitrates, peak traffic hours and main roads located close to the source also affected the results for both sites. This significant traffic corridor exemplifies the type of sources present in heavily trafficked locations and future attempts to control pollution in this type of environment could focus on the sources that were identified.

  8. The effects of particle concentration, ionic strength and shearing on the microstructure of alumina nanorod suspensions

    Science.gov (United States)

    Kim, Seokwon; Kim, Chongyoup

    2012-03-01

    In the present study we investigated the microstructure of suspensions of alumina nanorods while varying particle loading and pH. The diameter and length of rod particles were 10 and 50 nm, respectively and particle loading was varied from 1 to 5 vol%. Using the optical microscopy, dynamic light scattering, Turbiscan and rheological measurement, we showed that the suspensions existed as weakly flocculated gels at pH = 4 while they became strongly flocculated gels when pH was 7 or 11. The cryo-SEM images confirmed that the rod suspensions had gel structures. Strong shearing by milling or sonication changed the microstructure to a certain degree but the basic honeycomb structure was maintained.

  9. 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.

  10. Natural and man-made hexavalent chromium, Cr(VI), in groundwater near a mapped plume, Hinkley, California—study progress as of May 2017, and a summative-scale approach to estimate background Cr(VI) concentrations

    Science.gov (United States)

    Izbicki, John A.; Groover, Krishangi D.

    2018-03-22

    This report describes (1) work done between January 2015 and May 2017 as part of the U.S. Geological Survey (USGS) hexavalent chromium, Cr(VI), background study and (2) the summative-scale approach to be used to estimate the extent of anthropogenic (man-made) Cr(VI) and background Cr(VI) concentrations near the Pacific Gas and Electric Company (PG&E) natural gas compressor station in Hinkley, California. Most of the field work for the study was completed by May 2017. The summative-scale approach and calculation of Cr(VI) background were not well-defined at the time the USGS proposal for the background Cr(VI) study was prepared but have since been refined as a result of data collected as part of this study. The proposed summative scale consists of multiple items, formulated as questions to be answered at each sampled well. Questions that compose the summative scale were developed to address geologic, hydrologic, and geochemical constraints on Cr(VI) within the study area. Each question requires a binary (yes or no) answer. A score of 1 will be assigned for an answer that represents data consistent with anthropogenic Cr(VI); a score of –1 will be assigned for an answer that represents data inconsistent with anthropogenic Cr(VI). The areal extent of anthropogenic Cr(VI) estimated from the summative-scale analyses will be compared with the areal extent of anthropogenic Cr(VI) estimated on the basis of numerical groundwater flow model results, along with particle-tracking analyses. On the basis of these combined results, background Cr(VI) values will be estimated for “Mojave-type” deposits, and other deposits, in different parts of the study area outside the summative-scale mapped extent of anthropogenic Cr(VI).

  11. Tritium Concentrations in Environmental Samples and Transpiration Rates from the Vicinity of Mary's Branch Creek and Background Areas, Barnwell, South Carolina, 2007-2009

    Science.gov (United States)

    Vroblesky, Don A.; Canova, Judy L.; Bradley, Paul M.; Landmeyer, James E.

    2009-01-01

    Tritium in groundwater from a low-level radioactive waste disposal facility near Barnwell, South Carolina, is discharging to Mary's Branch Creek. The U.S. Geological Survey conducted an investigation from 2007 to 2009 to examine the tritium concentration in trees and air samples near the creek and in background areas, in groundwater near the creek, and in surface water from the creek. Tritium was found in trees near the creek, but not in trees from background areas or from sites unlikely to be in direct root contact with tritium-contaminated groundwater. Tritium was found in groundwater near the creek and in the surface water of the creek. Analysis of tree material has the potential to be a useful tool in locating shallow tritium-contaminated groundwater. A tritium concentration of 1.4 million picocuries per liter was measured in shallow groundwater collected near a tulip poplar located in an area of tritium-contaminated groundwater discharge. Evapotranspiration rates from the tree and tritium concentrations in water extracted from tree cores indicate that during the summer, this tulip poplar may remove more than 17.1 million picocuries of tritium per day from the groundwater that otherwise would discharge to Mary's Branch Creek. Analysis of air samples near the tree showed no evidence that the transpirative release of tritium to the air created a vapor hazard in the forest.

  12. Identification of 210Pb and 210Po in the bulk of copper samples with a low-background alpha particle counter

    Science.gov (United States)

    Abe, K.; Hiraide, K.; Ichimura, K.; Kishimoto, Y.; Kobayashi, K.; Kobayashi, M.; Moriyama, S.; Nakahata, M.; Norita, T.; Ogawa, H.; Sato, K.; Sekiya, H.; Takachio, O.; Takeda, A.; Tasaka, S.; Yamashita, M.; Yang, B. S.; Kim, N. Y.; Kim, Y. D.; Itow, Y.; Kanzawa, K.; Kegasa, R.; Masuda, K.; Takiya, H.; Fushimi, K.; Kanzaki, G.; Martens, K.; Suzuki, Y.; Xu, B. D.; Fujita, R.; Hosokawa, K.; Miuchi, K.; Oka, N.; Takeuchi, Y.; Kim, Y. H.; Lee, K. B.; Lee, M. K.; Fukuda, Y.; Miyasaka, M.; Nishijima, K.; Nakamura, S.

    2018-03-01

    We established a method to assay 210Pb and 210Po contaminations in the bulk of copper samples using a low-background alpha particle counter. The achieved sensitivity for the 210Pb and 210Po contaminations reaches a few mBq/kg. Due to this high sensitivity, the 210Pb and 210Po contaminations in oxygen free copper bulk were identified and measured for the first time. The 210Pb contaminations of our oxygen free copper samples were 17-40 mBq/kg. Based on our investigation of copper samples in each production step, the 210Pb in oxygen free copper was understood to be a small residual of an electrolysis process. This method to measure bulk contaminations of 210Pb and 210Po could be applied to other materials.

  13. The separation efficiency of ceramic barrier filters determined at high temperatures by optical particle size and concentration measurement

    Energy Technology Data Exchange (ETDEWEB)

    Hemmer, G.; Umhauer, H.; Kasper, G. [Univ. Karlsruhe, Inst. fuer Mechanische Verfahrenstechnik und Mechanik, Karlsruhe (Germany); Berbner, S. [Freudenberg Nonwovens, Filtration Div., Hopkinsville, KY (United States)

    1999-07-01

    Based on the experiences of earlier investigations a special optical particle counter was developed capable of recording size and quantity (concentration) of the particles directly within a given gas particle stream under the prevailing conditions (true in-situ measurements at high temperatures). In addition to earlier investigations [1], a second type of ceramic filter media with much smaller porosity and a membrane layer on the filtration side was tested. The candles with a length of 1.5 m which are used in industrial applications were mounted in the same hot gas filtration unit already used before. Measurements on the clean gas side at temperatures of up to 1000 C have been conducted using a fraction of quartz particles as test dust. The particle size ranged between 0.3 {mu}m and 10 {mu}m. Filtration velocity (1.5 cm/s) and final pressure drop of dust cake {delta}p (1000 Pa) were kept constant. As a main result the fractional efficiency as function of temperature is discussed and compared with that obtained before for a filter media of type I: The fractional efficiency values of filter type II are at least 100 times higher than that of filter type I. (orig.)

  14. The influence of weather-type and long-range transport on airborne particle concentrations in Edinburgh, UK

    Science.gov (United States)

    Buchanan, C. M.; Beverland, I. J.; Heal, M. R.

    This study investigated the influence of regional-scale synoptic weather type and geographical source regions of air masses on two-particle concentration metrics (Black Smoke (BS) and PM 10) in the city of Edinburgh, UK, between 1981 and 1996. Twenty-seven classifications of Jenkinson Daily Weather Types (JWT) were sub-divided into 9 directional categories and 3 vorticity categories, and the influence of JWT category on BS and PM 10 determined. Four-day air mass back-trajectories for 1 July 1995-30 June 1996 were computed and grouped into 8 categories depending on the geographical route followed. Significantly elevated concentrations of BS (median values 2, 5 and 4 μg m -3 greater than median for 1981-1996) and PM 10 (median values 3, 5.5 and 8 μg m -3 greater than median for 1992-1996) were observed for anticyclonic, southerly and south-easterly weather types, respectively. These differences were not identified at conventional levels of significance for BS in 1995-1996. This may reflect a shift in more recent times to lower concentrations of predominantly locally emitted BS less affected by regional scale meteorology. Conversely, significant inter-trajectory category differences were observed for PM 10 during 1995-1996, with highest concentrations associated with Eastern European trajectories and south-easterly weather type categories (11.4 and 10.7 μg m -3 greater than annual means, respectively). The variation in particle concentration across weather-type was a significant proportion of total median particle concentration, and of a magnitude associated with adverse health outcomes. Thus current PM 10 concentrations (and associated health outcomes) in Edinburgh are likely to be significantly influenced by regional-scale meteorology independent of local air quality management areas. Furthermore, changes in long-term trends in distributions of synoptic weather types indicate that future climate change may influence exposure to PM 10 and the PM 10:BS ratio in

  15. Effects of locust bean gum and mono- and diglyceride concentrations on particle size and melting rates of ice cream.

    Science.gov (United States)

    Cropper, S L; Kocaoglu-Vurma, N A; Tharp, B W; Harper, W J

    2013-06-01

    The objective of this study was to determine how varying concentrations of the stabilizer, locust bean gum (LBG), and different levels of the emulsifier, mono- and diglycerides (MDGs), influenced fat aggregation and melting characteristics of ice cream. Ice creams were made containing MDGs and LBG singly and in combination at concentrations ranging between 0.0% to 0.14% and 0.0% to 0.23%, respectively. Particle size analysis, conducted on both the mixes and ice cream, and melting rate testing on the ice cream were used to determine fat aggregation. No significant differences (P ice cream mixes. However, higher concentrations of both LBG and MDG in the ice creams resulted in values that were larger than the control. This study also found an increase in the particle size values when MDG levels were held constant and LBG amounts were increased in the ice cream. Ice creams with higher concentrations of MDG and LBG together had the greatest difference in the rate of melting than the control. The melting rate decreased with increasing LBG concentrations at constant MDG levels. These results illustrated that fat aggregation may not only be affected by emulsifiers, but that stabilizers may play a role in contributing to the destabilization of fat globules. © 2013 Institute of Food Technologists®

  16. 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...

  17. Optical tweezers in concentrated colloidal dispersions : Manipulating and imaging individual particles

    NARCIS (Netherlands)

    Vossen, Dirk Leo Joep

    2004-01-01

    Using a laser beam that is focused down to a diffraction-limited spot, particles with a size ranging from several nanometers up to tens of micrometers can be trapped and manipulated. This technique, known as "optical tweezers" or "optical trapping", has been used in a wide variety of

  18. Impact of the air filtration on indoor particle concentration by using combination filters in offices building

    Science.gov (United States)

    Kabrein, H.; Hariri, A.; Leman, A. M.; Noraini, N. M. R.; Yusof, M. Z. M.; Afandi, A.

    2017-09-01

    Heating ventilation and air conditioning system (HVAC) is very important for offices building and human health. The combining filter method was used to reduce the air pollution indoor such as that particulate matter and gases pollution that affected in health and productivity. Using particle filters in industrial HVAC systems (factories and manufacturing process) does not enough to remove all the indoor pollution. The main objective of this study is to investigate the impact of combination filters for particle and gases removal efficiency. The combining method is by using two filters (particulate filter pre-filter and carbon filter) to reduce particle matter and gases respectively. The purpose of this study is to use minimum efficiency reporting value (MERV filter) rating 13 and activated carbon filter (ACF) to remove indoor air pollution and controlling the air change rate to enhance the air quality and energy saving. It was concluded that the combination filter showed good removal efficiency of particle up to 90.76% and 89.25% for PM10 and PM2.5 respectively. The pressure drop across the filters was small compared with the high-efficiency filters. The filtration efficiency of combination filters after three months’ was better than efficiency by the new MERV filter alone.

  19. Spatially and angularly resolved spectroscopy for in-situ estimation of concentration and particle size in colloidal suspensions.

    Science.gov (United States)

    Chen, Yi-Chieh; Foo, David; Dehanov, Nicolau; Thennadil, Suresh N

    2017-12-01

    Successful implementation of process analytical technology (PAT) hinges on the ability to make continuous or frequent measurements in-line or at-line of critical product attributes such as composition and particle size, the latter being an important parameter for particulate processes such as suspensions and emulsions. A novel probe-based spatially and angularly-resolved diffuse reflectance measurement (SAR-DRM) system is proposed. This instrument, along with appropriate calibration models, is designed for online monitoring of concentration of chemical species and particle size of the particulate species in process systems involving colloidal suspensions. This measurement system was investigated using polystyrene suspensions of various particle radius and concentration to evaluate its performance in terms of the information obtained from the novel configuration which allows the measurement of a combination of incident light at different angles and collection fibres at different distances from the source fibres. Different strategies of processing and combining the SAR-DRM measurements were considered in terms of the impact on partial least squares (PLS) model performance. The results were compared with those obtained using a bench-top instrument which was used as the reference (off-line) instrument for comparison purposes. The SAR-DRM system showed similar performance to the bench top reference instrument for estimation of particle radius, and outperforms the reference instrument in estimating particle concentration. The investigation shows that the improvement in PLS regression model performance using the SAR-DRM system is related to the extra information captured by the SAR-DRM configuration. The differences in SAR-DRM spectra collected by the different collection fibres from different angular source fibres are the dominant reason for the significant improvement in the model performance. The promising results from this study suggest the potential of the SAR

  20. Analysis of the Reduction Rate of Hematite Concentrate Particles in the Solid State by H2 or CO in a Drop-Tube Reactor Through CFD Modeling

    Science.gov (United States)

    Fan, De-Qiu; Sohn, H. Y.; Elzohiery, Mohamed

    2017-10-01

    The kinetic analysis of the reduction of hematite concentrate particles by individual reducing gas H2 or CO was performed using a computational fluid dynamics (CFD)-based approach in this paper. The particle residence time was calculated through the integration of the equation of particle motion. Non-uniform particle temperature profiles inside the reactor were obtained, and were taken into consideration for the kinetic analysis. The calculated reduction degrees based on this approach are in good agreement with the experimental values.

  1. Trends in size classified particle number concentration in subtropical Brisbane, Australia, based on a 5 year study

    Science.gov (United States)

    Mejía, J. F.; Wraith, D.; Mengersen, K.; Morawska, L.

    Particle number size distribution data in the range from 0.015 to 0.630 μm were collected over a 5-year period in the central business district (CBD) of Brisbane, Australia. Particle size distribution was summarised by total number concentration and number median diameter (NMD) as well as the number concentration of the 0.015-0.030 ( N15-30), 0.030-0.050 ( N30-50), 0.050-0.100 ( N50-100), 0.100-0.300 ( N100-300) and 0.300-0.630 ( N300-630) μm size classes. Morning (6:00-10:00) and afternoon (16:00-19:00) measurements, the former representing fresh traffic emissions (based on the local meteorological conditions) and the latter well-mixed emissions from the CBD, during weekdays were extracted and the respective monthly mean values were estimated for time series analysis. For all size fractions, average morning concentrations were about 1.5 higher than in the afternoon whereas NMD did not vary between the morning and afternoon. The trend and seasonal components were extracted through weighted linear regression models, using the monthly variance as weights. Only the morning measurements exhibited significant trends. During this time of the day, total particle number increased by 105.7% and the increase was greater for larger particles, resulting in a shift in NMD by 7.9%. Although no seasonal component was detected the evidence against it remained weak due to the limitations of the database.

  2. 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.

  3. Effect of particle size and ammonium sulfate concentration on rice bran fermentation with the fungus Rhizopus oryzae.

    Science.gov (United States)

    Schmidt, Cristiano Gautério; Furlong, Eliana Badiale

    2012-11-01

    The effects of rice bran particle size (0.18-0.39mm) and ammonium sulfate concentration in the nutrient solution (2-8g/L) on biomass production, protein and phenolic content generated by solid state fermentation with the fungus Rhizopus oryzae (CCT 1217) were studied. Particle size had a positive effect on biomass production and a negative effect (p⩽0.05) on protein and phenolic contents. Ammonium sulfate concentration had a positive effect (p⩽0.05) on biomass and phenolic content gain. Cultivation of fungus in rice bran with particle size of 0.18mm and in the presence of 8g/L ammonium sulfate, resulted in protein levels of 20g/100g dry wt and phenolics content of 4mg/g dry wt. These values were 53 and 65% higher than those achieved with unfermented rice bran. The results demonstrate that the fermentation process increased the value of compounds recovered for potential use in food formulations. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Brominated flame retardants in the urban atmosphere of Northeast China: concentrations, temperature dependence and gas-particle partitioning.

    Science.gov (United States)

    Qi, Hong; Li, Wen-Long; Liu, Li-Yan; Song, Wei-Wei; Ma, Wan-Li; Li, Yi-Fan

    2014-09-01

    57 pairs of air samples (gas and particle phases) were collected using a high volume air sampler in a typical city of Northeast China. Brominated flame retardants (BFRs) including 13 polybrominated diphenyl ethers (PBDEs, including BDEs 17, 28, 47, 49, 66, 85, 99, 100, 138, 153, 154, 183, and 209) and 9 alternative BFRs (p-TBX, PBBZ, PBT, PBEB, DPTE, HBBZ, γ-HBCD, BTBPE, and DBDPE) were analyzed. The annual average total concentrations of the 13 PBDEs and the 9 alternative BFRs were 69 pg/m(3) and 180 pg/m(3), respectively. BDE 209 and γ-HBCD were the dominant congeners, according to the one-year study. The partial pressure of BFRs in the gas phase was significantly correlated with the ambient temperature, except for BDE 85, γ-HBCD and DBDPE, indicating the important influence of ambient temperature on the behavior of BFRs in the atmosphere. It was found that the gas-particle partitioning coefficients (logKp) for most low molecular weight BFRs were highly temperature dependent as well. Gas-particle partitioning coefficients (logKp) also correlated with the sub-cooled liquid vapor pressure (logPL(o)). Our results indicated that absorption into organic matter is the main control mechanism for the gas-particle partitioning of atmospheric PBDEs. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. 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

  6. Particle concentration effect: adsorption of divalent metal ions on coffee grounds.

    Science.gov (United States)

    Utomo, Handojo Djati; Hunter, Keith A

    2010-03-01

    The adsorption of divalent metal ions Cu2+, Pb2+, Zn2+, and Cd2+ on coffee grounds as a function of coffee grounds concentration was studied in which adsorption density decreased as the concentration of coffee grounds (C(s)) increased. Adsorption studies were conducted by equilibrating aqueous solutions of each metal ion at concentrations in the range 19-291 micromol L(-1) with coffee suspensions in the concentration range 0.971-8.738 g L(-1), with the initial pH adjusted to 5.0+/-0.1 using NaOH or HNO3. Metastable Equilibrium Adsorption theory did not adequately explain the adsorption phenomenon, except at low concentrations of coffee grounds and trace metal ions. Instead the results indicated that flocculation might reduce the surface availability thus reducing the adsorption density. The flocculation theory was confirmed after a further experiment adding dispersant sodium hexa-meta-phosphate (NaHMP) to the suspension. 2009 Elsevier Ltd. All rights reserved.

  7. Environmental 238U and 232Th concentration measurements in an area of high level natural background radiation at Palong, Johor, Malaysia.

    Science.gov (United States)

    Ramli, A Termizi; Hussein, A Wahab M A; Wood, A Khalik

    2005-01-01

    Concentrations of uranium-238 and thorium-232 in soil, water, grass, moss and oil-palm fruit samples collected from an area of high background radiation were determined using neutron activation analysis (NAA). U-238 concentration in soil ranged from 4.9 mg kg(-1) (58.8 Bq kg(-1)) to 40.4 mg kg(-1) (484.8 Bq kg(-1)), Th-232 concentration ranged from 14.9 mg kg(-1) (59.6 Bq kg(-1)) to 301.0 mg kg(-1) (1204 Bq kg(-1)). The concentration of U-238 in grass samples ranged from below the detection limit to 0.076 mg kg(-1) (912 mBq kg(-1)), and Th-232 ranged from 0.008 mg kg(-1) (32 mBq kg(-1)) to 0.343 mg kg(-1) (1.372 Bq kg(-1)). U-238 content in water samples ranged from 0.33 mg kg(-1) (4.0 Bq L(-1)) to 1.40 mg kg(-1) (16.8 Bq L(-1)), and Th-232 ranged from 0.19 mg kg(-1) (0.76 Bq L(-1)) to 0.66 mg kg(-1) (2.64 Bq L(-1)). It can be said that the concentrations of environmental U-238 and Th-232 in grass and water samples in the study area are insignificant. Mosses were found to be possible bio-radiological indicators due to their high absorption of the heavy radioelements from the environment.

  8. A cosmic-ray nuclear event with an anomalously strong concentration of energy and particles in the central region

    International Nuclear Information System (INIS)

    Amato, N.M.; Arata, N.; Maldonado, R.H.C.

    1986-01-01

    A cosmic-ray induced nuclear event detected in the emulsion chamber is described. The event consists of 217 shower cores with ΣEγ = 1,275 TeV. In log scale, energy and particles are emitted most densely at the small lateral distance corresponding to 0.5 mm; 77 % of the total energy and 61 % of the total multiplicity are inside the radius of 0.65 cm. The shower cores in the central region show exponential-type energy distribution and non-isotropic azimuthal distribution. This event indicates a possibility that phenomena of large transverse momentum could happen to produce a strong concentration of energy and particles in the very forward direction. (Authors) [pt

  9. 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.

  10. Brominated flame retardants in the urban atmosphere of Northeast China: Concentrations, temperature dependence and gas-particle partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Hong; Li, Wen-Long; Liu, Li-Yan; Song, Wei-Wei; Ma, Wan-Li, E-mail: mawanli002@163.com; Li, Yi-Fan, E-mail: ijrc_pts_paper@yahoo.com

    2014-09-01

    57 pairs of air samples (gas and particle phases) were collected using a high volume air sampler in a typical city of Northeast China. Brominated flame retardants (BFRs) including 13 polybrominated diphenyl ethers (PBDEs, including BDEs 17, 28, 47, 49, 66, 85, 99, 100, 138, 153, 154, 183, and 209) and 9 alternative BFRs (p-TBX, PBBZ, PBT, PBEB, DPTE, HBBZ, γ-HBCD, BTBPE, and DBDPE) were analyzed. The annual average total concentrations of the 13 PBDEs and the 9 alternative BFRs were 69 pg/m{sup 3} and 180 pg/m{sup 3}, respectively. BDE 209 and γ-HBCD were the dominant congeners, according to the one-year study. The partial pressure of BFRs in the gas phase was significantly correlated with the ambient temperature, except for BDE 85, γ-HBCD and DBDPE, indicating the important influence of ambient temperature on the behavior of BFRs in the atmosphere. It was found that the gas–particle partitioning coefficients (logK{sub p}) for most low molecular weight BFRs were highly temperature dependent as well. Gas–particle partitioning coefficients (logK{sub p}) also correlated with the sub-cooled liquid vapor pressure (logP{sub L}{sup o}). Our results indicated that absorption into organic matter is the main control mechanism for the gas–particle partitioning of atmospheric PBDEs. - Highlights: • Both PBDEs and alternative BFRs were analyzed in the atmosphere of Northeast China. • Partial pressure of BFRs was significantly correlated with the ambient temperature. • A strong temperature dependence of gas-particle partitioning was found. • Absorption into organic matter was the control mechanism for G-P partitioning.

  11. Intramembraneous Particle Cluster and Cytoplasmic Vesicles in Mice with Nephrogenic Defects of Urinary Concentration.

    Science.gov (United States)

    1987-01-01

    sphincter control released urine stored in the bladder. The animals were sacrificed by cervical dislocation. After a mid- abdominal incision was made, the... reabsorption of NaCl from those limbs. Therefore, at least part of the difficulty that these animals have in concentrating their urine might stem from an

  12. Concentrations and compositions of colloidal particles in groundwater near the ICPP, Idaho National Laboratory, Idaho

    International Nuclear Information System (INIS)

    Estes, M.; McCurry, M.

    1994-01-01

    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

  13. Structural state diagram of concentrated suspensions of jammed soft particles in oscillatory shear flow

    Science.gov (United States)

    Khabaz, Fardin; Cloitre, Michel; Bonnecaze, Roger T.

    2018-03-01

    In a recent study [Khabaz et al., Phys. Rev. Fluids 2, 093301 (2017), 10.1103/PhysRevFluids.2.093301], we showed that jammed soft particle glasses (SPGs) crystallize and order in steady shear flow. Here we investigate the rheology and microstructures of these suspensions in oscillatory shear flow using particle-dynamics simulations. The microstructures in both types of flows are similar, but their evolutions are very different. In both cases the monodisperse and polydisperse suspensions form crystalline and layered structures, respectively, at high shear rates. The crystals obtained in the oscillatory shear flow show fewer defects compared to those in the steady shear. SPGs remain glassy for maximum oscillatory strains less than about the yield strain of the material. For maximum strains greater than the yield strain, microstructural and rheological transitions occur for SPGs. Polydisperse SPGs rearrange into a layered structure parallel to the flow-vorticity plane for sufficiently high maximum shear rates and maximum strains about 10 times greater than the yield strain. Monodisperse suspensions form a face-centered cubic (FCC) structure when the maximum shear rate is low and hexagonal close-packed (HCP) structure when the maximum shear rate is high. In steady shear, the transition from a glassy state to a layered one for polydisperse suspensions included a significant induction strain before the transformation. In oscillatory shear, the transformation begins to occur immediately and with different microstructural changes. A state diagram for suspensions in large amplitude oscillatory shear flow is found to be in close but not exact agreement with the state diagram for steady shear flow. For more modest amplitudes of around one to five times the yield strain, there is a transition from a glassy structure to FCC and HCP crystals, at low and high frequencies, respectively, for monodisperse suspensions. At moderate frequencies, the transition is from glassy to HCP via

  14. 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

  15. New Small LWR Core Designs using Particle Burnable Poisons for Low Boron Concentration

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Ho Seong; Hwang, Dae Hee; Hong, Ser Gi [Kyung Hee University, Yongin (Korea, Republic of)

    2015-05-15

    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.

  16. Round-shape gold nanoparticles: effect of particle size and concentration on Arabidopsis thaliana root growth

    Czech Academy of Sciences Publication Activity Database

    Siegel, J.; Záruba, K.; Švorčík, V.; Kroumanová, Kristýna; Burketová, Lenka; Martinec, Jan

    2018-01-01

    Roč. 13, APR 10 (2018), č. článku 95. ISSN 1556-276X R&D Projects: GA ČR GA17-10907S; GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:61389030 Keywords : Arabidopsis thaliana * Concentration * Gold nanoparticles * Root growth * Size Subject RIV: JJ - Other Materials OBOR OECD: Plant sciences, botany Impact factor: 2.833, year: 2016

  17. 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.

  18. 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.

  19. Bidirectional reflectance study on dry, wet, and submerged particulate layers: effects of pore liquid refractive index and translucent particle concentrations.

    Science.gov (United States)

    Zhang, Hao; Voss, Kenneth J

    2006-12-01

    We performed extensive bidirectional reflectance measurements on dry, wet, and submerged particulate layers with various albedos to investigate the darkening effect caused by wetting with fluids. It was found that, in addition to the reduction of the refractive index contrast when there is a pore liquid (wetted), the concentration of translucent grains in a particulate layer and the surface roughness conditions of the individual grains make important contributions to the wetting-induced darkening effect. Reflectance measurements on glass-sediment mixtures confirmed that, as the concentration of translucent particles increases, the reflectance of the dry layers increases while that of the wetted layers decreases. Measurements indicate that neither the prediction made by the theory of Twomey et al. [Appl. Opt. 25, 431 (1986)] nor that of Lekner and Dorf [Appl. Opt. 27, 1278 (1988)] is sufficient.

  20. Assessment of environmental (226)Ra, (232)Th and (40)K concentrations in the region of elevated radiation background in Segamat District, Johor, Malaysia.

    Science.gov (United States)

    Saleh, Muneer Aziz; Ramli, Ahmad Termizi; Alajerami, Yasser; Aliyu, Abubakar Sadiq

    2013-10-01

    Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276 nGy h(-1) and 1.169 mSv y(-1), respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of (232)Th, (226)Ra and (40)K. The results of the gamma spectrometry range from 11 ± 1 to 1210 ± 41 Bq kg(-1) for (232)Th, 12 ± 1 to 968 ± 27 Bq kg(-1) for (226)Ra, and 12 ± 2 to 2450 ± 86 Bq kg(-1) for (40)K. Gross alpha and gross beta activity concentrations range from 170 ± 50 to 4360 ± 170 Bq kg(-1) and 70 ± 20 to 4690 ± 90 Bq kg(-1), respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Background sources at PEP

    International Nuclear Information System (INIS)

    Lynch, H.; Schwitters, R.F.; Toner, W.T.

    1988-01-01

    Important sources of background for PEP experiments are studied. Background particles originate from high-energy electrons and positrons which have been lost from stable orbits, γ-rays emitted by the primary beams through bremsstrahlung in the residual gas, and synchrotron radiation x-rays. The effect of these processes on the beam lifetime are calculated and estimates of background rates at the interaction region are given. Recommendations for the PEP design, aimed at minimizing background are presented. 7 figs., 4 tabs

  2. 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 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 the protein sources did not influence the composition of protein flowing to the intestine and site and extent of nutrient digestibility.

  3. Magnetic hyperthermia in magnetic nanoemulsions: Effects of polydispersity, particle concentration and medium viscosity

    Science.gov (United States)

    Lahiri, B. B.; Ranoo, Surojit; Zaibudeen, A. W.; Philip, John

    2017-11-01

    Magnetic fluid hyperthermia (MFH) is a promising cancer treatment modality where alternating magnetic field is used for heating cancerous cells loaded with magnetic nanofluids. Of late, it is realized that magnetic nano-carriers in the size range ∼100-200 nm (e.g. magnetic nanocomposites, magnetic liposomes and magnetic nanoemulsions) are ideal candidates for multimodal MFH coupled with drug delivery or photodynamic therapy due to enhanced permeation and retention (EPR) in the leaky vasculature of cancerous tissues. Here, we study the radiofrequency alternating magnetic field induced heating in magnetically polarizable oil-in-water nanoemulsions of hydrodynamic diameter ∼200 nm, containing single domain superparamagnetic nanoparticles of average diameter ∼10 nm in the oil phase. We probe the effects of size polydispersity of the droplets and medium viscosity on the field induced heating efficiency. The contribution of Neel and Brown relaxation of the magnetic nanoparticles on specific absorption rate (SAR) of the magnetic nanoemulsions, was found to increase linearly with the square of the applied field, with a maximum value of 164.4 ± 4.3 W/gFe. In magnetic nanoemulsions, the heating is induced by the Neel-Brown relaxation of the MNP over a length scale of 10 nm, and the whole scale Brownian relaxation of the emulsion droplets has over a length scale of 200 nm. The magnetic nanoemulsion sample with lower polydispersity (σ = 0.2) exhibited a significantly higher SAR value (3.3 times higher) as compared to the sample with larger polydispersity (σ = 0.4). The SAR values of the samples with 4.6 and 1.7 wt.% of MNP loading with σ values 0.4 a 0.3, respectively were comparable, suggesting a higher heating efficiency in nanofluid containing particles of lower size polydispersity even at lower particle loading. The emulsion droplets, immobilized in an agar matrix (4 wt.%), gave a maximum SAR value of 41.7 ± 2.4 W/gFe as compared to 111.8 ± 3.4 W/gFe in the

  4. 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.

  5. Worker Exposure and High Time-Resolution Analyses of Process-Related Submicrometre Particle Concentrations at Mixing Stations in Two Paint Factories.

    Science.gov (United States)

    Koponen, Ismo Kalevi; Koivisto, Antti Joonas; Jensen, Keld Alstrup

    2015-07-01

    The paint and coatings industry is known to have significant particulate matter (PM) emissions to the atmosphere. However, exposure levels are not studied in detail especially when considering submicrometre (PM1) and ultrafine particles (particle diameter below 100nm). The evidence is increasing that pulmonary exposures to these size fractions are potentially very harmful. This study investigates particle emissions during powder handling and paint mixing in two paint factories at two mixing stations in each factory. In each case measurements were made simultaneously at the mixing station (near-field; NF), as well as at 5-15 m distance into the workroom far-field (FF), and in the workers breathing zone. Particle concentrations (5nm to 30 µm) were measured using high time-resolution particle instruments and gravimetrically using PM1 cyclone filter samplers. The PM1 filters were also characterized by scanning electron microscopy (SEM). The NF particle and dust concentration levels were linked to pouring powder and were used to characterize the emissions and efficiencies of localized controls. NF particle number concentrations were 1000-40000cm(-3) above FF concentrations. NF particles were mainly between 100 and 500nm and emissions appeared to occur in short bursts. Personal PM1 exposure levels varied between 0.156 and 0.839mg m(-3) and were 1.6-15 times higher than stationary NF PM1 concentrations. SEM results verified that the personal exposure and NF particles were strongly dominated by the pigments and fillers used. Better understanding of the entire temporal personal exposure could be improved by using real-time particle monitors for personal exposure measurements. This study provides better insight into PM exposure characteristics and concentration levels in the paint industry. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  6. Determining H2O Vapor Temperature and Concentration in Particle-Free and Particle-Laden Combustion Flows Using Spectral Line Emission Measurements

    Science.gov (United States)

    Tobiasson, John Robert

    2017-07-01

    There is a growing need for the clean generation of electricity in the world, and increased efficiency is one way to achieve cleaner generation. Increased efficiency may be achieved through an improved understanding of the heat flux of participating media in combustion environments. Real-time in-situ optical measurements of gas temperature and concentrations in combustion environments is needed. Optical methods do not disturb the flow characteristics and are not subject to the temperature limitation of current methods. Simpler, less-costly optical measurements than current methods would increase the ability to apply them in more circumstances. This work explores the ability to simultaneously measure gas temperature and H2O concentration via integrated spectral intensity ratios in regions where H2O is the dominant participating gas. This work considered combustion flows with and without fuel and soot particles, and is an extension of work previously performed by Ellis et al. [1]. Five different combustion regimes were used to investigate the robustness of the infrared intensity integral method first presented by Ellis et al. [1]. These included Post-Flame Natural Gas (PFNG), Post-Flame Medium Wood (PFMW), Post-Flame Fine Wood (PFFW), In-Flame Natural Gas (IFNG), and In-Flame Fine Wood (IFFW). Optical spectra were collected as a function of path length for each regime. Methods for processing the spectra to obtain gas temperature, gas concentration, broadband temperature, and broadband emissivity were developed. A one-dimensional spectral intensity model that allowed for specular reflection, and investigated differences between measured and modeled spectral intensities was created. It was concluded that excellent agreement (within 2.5%) was achieved between optical and suction pyrometer gas temperatures as long as 1) the optical probe and cold target used were well-aligned 2) the path length was greater than 0.3 m and 3) the intensity from broadband emitters within

  7. Effect of (Cd:Zn)S Particle Concentration and Photoexcitation on the Electrical and Ferroelectric Properties of (Cd:Zn)S/P(VDF-TrFE) Composite Films

    OpenAIRE

    Sebastian Engel; David Smykalla; Bernd Ploss; Stephan Gräf; Frank A. Müller

    2017-01-01

    The influence of semiconductor particle concentration and photoexcitation on the electrical and ferroelectric properties of ferroelectric-semiconductor-composites was investigated. For this purpose, 32 µm thin films of poly(vinylidene fluoride-co-trifluoroethylene) with (Cd:Zn)S particle concentrations of between 0 and 20 vol % were fabricated and characterized by scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, and optical spectroscopy. It was shown...

  8. Concentrations, loads, and yields of particle-associated contaminants in urban creeks, Austin, Texas, 1999-2004

    Science.gov (United States)

    Mahler, B.J.; Van Metre, P.C.; Wilson, J.T.; Guilfoyle, A.L.; Sunvison, M.W.

    2006-01-01

    Concentrations, loads, and yields of particle-associated (hydrophobic) contaminants (PACs) in urban runoff in creeks in Austin, Texas, were characterized using an innovative approach: large-volume suspended-sediment sampling. This approach isolates suspended sediment from the water column in quantities sufficient for direct chemical analysis of PACs. During 1999-2004, samples were collected after selected rain events from each of five stream sites and Barton Springs for a study by the U.S. Geological Survey, in cooperation with the City of Austin. Sediment isolated from composited samples was analyzed for major elements, metals, organochlorine compounds, and polycyclic aromatic hydrocarbons (PAHs). In addition, at the Shoal Creek and Boggy Creek sites, individual samples for some events were analyzed to investigate within-event variation in sediment chemistry. Organochlorine compounds detected in suspended sediment included chlordane, dieldrin, DDD, DDE, DDT, and polychlorinated biphenyls (PCBs). Concentrations of PACs varied widely both within and between sites, with higher concentrations at the more urban sites and multiple nondetections at the least-urban sites. Within-site variation for metals and PAHs was smaller than between-site variation, and concentrations and yields of these and the organochlorine compounds correlated positively to the percentage of urban land use in the watershed. Loads of most PACs tested correlated significantly with suspended-sediment loads. Concentrations of most PACs correlated strongly with three measures of urban land use. Variation in suspended-sediment chemistry during runoff events was investigated at the Shoal and Boggy Creek sites. Five of the eight metals analyzed, dieldrin, chlordane, PCBs, and PAHs were detected at the highest concentrations in the first sample collected at the Shoal Creek site, a first-flush effect, but not at the Boggy Creek site. Temporal patterns in concentrations of DDT and its breakdown products

  9. 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.

  10. Comparisons of traffic-related ultrafine particle number concentrations measured in two urban areas by central, residential, and mobile monitoring

    Science.gov (United States)

    Simon, Matthew C.; Hudda, Neelakshi; Naumova, Elena N.; Levy, Jonathan I.; Brugge, Doug; Durant, John L.

    2017-11-01

    Traffic-related ultrafine particles (UFP; urban air. While studies have shown that UFP are toxic, epidemiological evidence of health effects, which is needed to inform risk assessment at the population scale, is limited due to challenges of accurately estimating UFP exposures. Epidemiologic studies often use empirical models to estimate UFP exposures; however, the monitoring strategies upon which the models are based have varied between studies. Our study compares particle number concentrations (PNC; a proxy for UFP) measured by three different monitoring approaches (central-site, short-term residential-site, and mobile on-road monitoring) in two study areas in metropolitan Boston (MA, USA). Our objectives were to quantify ambient PNC differences between the three monitoring platforms, compare the temporal patterns and the spatial heterogeneity of PNC between the monitoring platforms, and identify factors that affect correlations across the platforms. We collected >12,000 h of measurements at the central sites, 1000 h of measurements at each of 20 residential sites in the two study areas, and >120 h of mobile measurements over the course of ∼1 year in each study area. Our results show differences between the monitoring strategies: mean 1 min PNC on-roads were higher (64,000 and 32,000 particles/cm3 in Boston and Chelsea, respectively) compared to central-site measurements (23,000 and 19,000 particles/cm3) and both were higher than at residences (14,000 and 15,000 particles/cm3). Temporal correlations and spatial heterogeneity also differed between the platforms. Temporal correlations were generally highest between central and residential sites, and lowest between central-site and on-road measurements. We observed the greatest spatial heterogeneity across monitoring platforms during the morning rush hours (06:00-09:00) and the lowest during the overnight hours (18:00-06:00). Longer averaging times (days and hours vs. minutes) increased temporal correlations

  11. Short-term variation in ambient concentrations and gas/particle partitioning of organochlorine pesticides in Izmir, Turkey

    Science.gov (United States)

    Sofuoglu, Aysun; Cetin, Eylem; Bozacioglu, Sevde Seza; Sener, Gaye Devrim; Odabasi, Mustafa

    Twenty successive daytime and nighttime air samples were collected and analyzed for 23 currently used and/banned organochlorine pesticides (OCPs) between 14 and 23 May 2003 in Izmir, Turkey. Average individual OCP concentrations ranged from 5±4 pg m -3 (p,p'-dichlorodiphenyldichloroethane) to 391±306 pg m -3 (chlorpyrifos) and they were within the ranges previously measured at different sites. Most of the OCPs did not exhibit strong diurnal cycling. The temperature dependence of gas-phase atmospheric concentrations of OCPs investigated using Clausius-Clapeyron plots was statistically significant for β-HCH and endosulfan sulfate ( pgas-phase concentrations). In addition to temperature, the effect of wind speed and direction was also investigated using multiple linear regression analysis and these three parameters together explained the 2% (aldrin) to 72% (endosulfan II) of the variability in gas-phase OCP concentrations. Results of the multiple regression analysis indicated that wind speed was a statistically significant factor for most of the OCPs and wind direction was important for some compounds. The temperature-dependent diurnal cycling of most OCPs was probably masked by the higher wind speeds observed during daytime periods with high temperatures, different source sectors and ongoing sources. The lack of correlation for heptachlor, aldrin, p,p'-dichlorodiphenyldichloroethylene (p-p'-DDE), and p,p'-dichlorodiphenyltrichloroethane (p-p'-DDT) with temperature, wind speed and direction suggested that their concentrations were affected by long-range transport. The partitioning of OCPs between particle and gas phases was investigated and compared to KOA (octanol/air partition coefficient) absorption model. The overall agreement between experimental and modeled log K p (gas/particle partition coefficient) values was good ( p<0.01, slope=0.94). Prediction of absorption model for particulate percentages was excellent for β-HCH, endosulfan I, and p-p'-DDT. However

  12. Determination of effective electromagnetic parameters of concentrated suspensions of ellipsoidal particles using Generalized Differential Effective Medium approximation

    Science.gov (United States)

    Markov, M.; Levin, V.; Markova, I.

    2018-02-01

    The paper presents an approach to determine the effective electromagnetic parameters of suspensions of ellipsoidal dielectric particles with surface conductivity. This approach takes into account the existence of critical porosity that corresponds to the maximum packing volume fraction of solid inclusions. The approach is based on the Generalized Differential Effective Medium (GDEM) method. We have introduced a model of suspensions containing ellipsoidal inclusions of two types. Inclusions of the first type (phase 1) represent solid grains, and inclusions of the second type (phase 2) contain material with the same physical properties as the host (phase 0). In this model, with increasing porosity the concentration of the host decreases, and it tends to zero near the critical porosity. The proposed model has been used to simulate the effective electromagnetic parameters of concentrated suspensions. We have compared the modeling results for electrical conductivity and dielectric permittivity with the empirical equations. The results obtained have shown that the GDEM model describes the effective electrical conductivity and dielectric permittivity of suspensions in a wide range of inclusion concentrations.

  13. Assessment of environmental 226Ra, 232Th and 40K concentrations in the region of elevated radiation background in Segamat District, Johor, Malaysia

    International Nuclear Information System (INIS)

    Saleh, Muneer Aziz; Ramli, Ahmad Termizi; Alajerami, Yasser; Aliyu, Abubakar Sadiq

    2013-01-01

    Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276 nGy h −1 and 1.169 mSv y −1 , respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of 232 Th, 226 Ra and 40 K. The results of the gamma spectrometry range from 11 ± 1 to 1210 ± 41 Bq kg −1 for 232 Th, 12 ± 1 to 968 ± 27 Bq kg −1 for 226 Ra, and 12 ± 2 to 2450 ± 86 Bq kg −1 for 40 K. Gross alpha and gross beta activity concentrations range from 170 ± 50 to 4360 ± 170 Bq kg −1 and 70 ± 20 to 4690 ± 90 Bq kg −1 , respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000. -- Highlights: • Assessment of the activities in region of elevated radiation in Segamat District. • The average dose rate found to be six times higher than the world average. • The activity of 232 Th is six times world average. • The activity of 226 Ra is four times and 40 K is lower than world average. • A digital map plotted for isodose

  14. Particle Size of Milk Protein Concentrate Powder Affects the Texture of High-Protein Nutrition Bars During Storage.

    Science.gov (United States)

    Banach, J C; Clark, S; Lamsal, B P

    2017-04-01

    Milk protein concentrate powder with 85% protein (MPC85) was jet-milled to give 2 particle size distributions (that is, JM-Coarse and JM-Fine) or freeze-dried (FD), in order to improve the functional properties of MPC85 for use in high-protein nutrition (HPN) bars. Volume-weighted mean diameter decreased from 86 μm to 49, 22, and 8 μm in FD, JM-Coarse, and JM-Fine, respectively (P powders modified by jet-milling and freeze-drying were significantly denser than the control MPC85 (P powders decreased (P < 0.05) by an order of magnitude, yet only FD possessed a lower volume of interstitial air (P < 0.05). Particle size reduction and freeze-drying MPC85 decreased its water holding capacity and improved its dispersibility by at least 20%. Contact angle measurements showed that these modifications increased initial hydrophobicity and did not improve wettability. HPN bars made from JM-Fine or FD were firmer by 40 or 17 N, respectively, than the control on day 0 (P < 0.05). HPN bar maximum compressive force increased by 38%, 33%, and 242% after 42 d at 32 °C when formulated with JM-Fine, FD, or control MPC85, respectively. HPN bars prepared with JM-Fine were less crumbly than those formulated with control or FD MPC85. Physically altering the particle structure of MPC85 improved its ability to plasticize within HPN bars and this improved their cohesiveness and textural stability. © 2017 Institute of Food Technologists®.

  15. Dissipative particle dynamics simulation of flow generated by two rotating concentric cylinders: II. Lateral dissipative and random forces

    International Nuclear Information System (INIS)

    Filipovic, N; Haber, S; Kojic, M; Tsuda, A

    2008-01-01

    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

  16. Effect of (Cd:ZnS Particle Concentration and Photoexcitation on the Electrical and Ferroelectric Properties of (Cd:ZnS/P(VDF-TrFE Composite Films

    Directory of Open Access Journals (Sweden)

    Sebastian Engel

    2017-11-01

    Full Text Available The influence of semiconductor particle concentration and photoexcitation on the electrical and ferroelectric properties of ferroelectric-semiconductor-composites was investigated. For this purpose, 32 µm thin films of poly(vinylidene fluoride-co-trifluoroethylene with (Cd:ZnS particle concentrations of between 0 and 20 vol % were fabricated and characterized by scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, and optical spectroscopy. It was shown that the particle concentration has only a negligible influence on the molecular structure of the polymer but strongly determines the optical properties of the composite. For (Cd:ZnS particle concentrations below 20 vol %, the I-V characteristics of the composites is only marginally affected by the particle concentration and the optical excitation of the composite material. On the contrary, a strong influence of both parameters on the ferro- and pyroelectric properties of the composite films was observed. For particle fractions that exhibit ferroelectric hysteresis, an increased remanent polarization and pyroelectric coefficient due to optical excitation was obtained. A theoretical approach that is based on a “three phase model” of the internal structure was developed to explain the observed results.

  17. O/W emulsions stabilised by both low molecular weight surfactants and colloidal particles: The effect of surfactant type and concentration.

    Science.gov (United States)

    Pichot, R; Spyropoulos, F; Norton, I T

    2010-12-01

    The stability against coalescence of O/W emulsions in the presence of both surfactants and colloidal particles was investigated. In particular the effect of the surfactant type and concentration in these emulsifier mixtures on the O/W emulsions' stability was studied. Two types of surfactants were selected; those that have the ability to stabilise O/W emulsions on their own (O/W surfactants) and those that cannot (W/O surfactants). Tween 60 and Sodium Caseinate were selected as the O/W surfactants and lecithin as the W/O surfactant. Oil-in-water emulsions prepared with both particles and any of the three surfactants were stable against coalescence but, depending on the type of surfactant, the behaviour of the systems was found to depend on surfactant concentration. The droplet sizes of emulsions stabilised by mixed emulsifier systems containing low concentrations of O/W surfactants (Tween 60 or Sodium Caseinate) were smaller than those solely stabilised by either the surfactant or particles alone. At intermediate O/W surfactants concentrations, the droplet sizes of the emulsions increased. Further increases in the O/W surfactants' concentration, resulted in the complete removal of particles from the interface with the system now behaving as a surfactant-only stabilised emulsion. The behaviour of emulsions stabilised by emulsifier mixtures containing W/O surfactants was not dependent on the concentration of surfactant: no removal of particles was observed. Copyright © 2010 Elsevier Inc. All rights reserved.

  18. A comparison of strategies for estimation of ultrafine particle number concentrations in urban air pollution monitoring networks

    International Nuclear Information System (INIS)

    Reggente, Matteo; Peters, Jan; Theunis, Jan; Van Poppel, Martine; Rademaker, Michael; De Baets, Bernard; Kumar, Prashant

    2015-01-01

    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, O 3 , 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, O 3 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

  19. Land use regression models for total particle number concentrations using 2D, 3D and semantic parameters

    Science.gov (United States)

    Ghassoun, Yahya; Löwner, Marc-Oliver

    2017-10-01

    Total particle number concentration (TNC) was studied in a 1 × 2 km area in Berlin, the capital of Germany by three Land Use Regression models (LUR). The estimation of TNC was established and compared using one 2D-LUR and two 3D-LUR models. All models predict total number concentrations TNC by using urban morphological (2D resp. 3D) and additional semantical parameters. 2D and semantical parameters were derived from Open Street Map data (OSM) whereas 3D parameters were derived from a CityGML-based 3D city model. While the models are capable to depict the spatial variation of TNC across the study area, the two 3D-LUR showed better results than the 2D-LUR. The 2D-LUR model explained 74% of the variance of TNC for the full data set with root mean square error (RMSE) of 4014 cm-3 while the 3D-LUR explained 79% of the variance with an RMSE of 3477 cm-3. The further introduction of a new spatial parameter, the Frontal Area Index (FAI) that represents the dynamic factor wind direction enhanced the 3D-LUR to explain 82% of the variance with RMSE of 3389 cm-3. Furthermore, the semantical parameters (e.g. streets type) played a significant role in all models.

  20. Determination of the vertical profile of particle number concentration adjacent to a motorway using an unmanned aerial vehicle.

    Science.gov (United States)

    Villa, T F; Jayaratne, E R; Gonzalez, L F; Morawska, L

    2017-11-01

    A quantitative assessment of the vertical profile of traffic pollution, specifically particle number concentration (PNC), in an open space adjacent to a motorway was possible for the first time, to the knowledge of the authors, using an Unmanned Aerial Vehicle (UAV) system. Until now, traffic pollution has only been measured at ground level while the vertical distribution, is limited to studies conducted from buildings or fixed towers and balloons. This new UAV system demonstrated that the PNC sampled during the period form 10 a.m. to 4 p.m., outside the rush hours with a constant traffic flow, increased from a concentration of 2 × 10 4 p/cm 3 near the ground up to 10 m, and then sharply decreased attaining a steady value of 4 × 10 3 p/cm 3 beyond a height of about 40 m. While more comprehensive investigations would be warranted under different conditions, such as topography and vehicle and fuel type, this finding is of great significance, given that it demonstrates the impact of traffic emissions on human exposure, but less so to pollution within the upper part of the boundary layer. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The Dependence of CNT Aerogel Synthesis on Sulfur-driven Catalyst Nucleation Processes and a Critical Catalyst Particle Mass Concentration.

    Science.gov (United States)

    Hoecker, Christian; Smail, Fiona; Pick, Martin; Weller, Lee; Boies, Adam M

    2017-11-06

    The floating catalyst chemical vapor deposition (FC-CVD) process permits macro-scale assembly of nanoscale materials, enabling continuous production of carbon nanotube (CNT) aerogels. Despite the intensive research in the field, fundamental uncertainties remain regarding how catalyst particle dynamics within the system influence the CNT aerogel formation, thus limiting effective scale-up. While aerogel formation in FC-CVD reactors requires a catalyst (typically iron, Fe) and a promotor (typically sulfur, S), their synergistic roles are not fully understood. This paper presents a paradigm shift in the understanding of the role of S in the process with new experimental studies identifying that S lowers the nucleation barrier of the catalyst nanoparticles. Furthermore, CNT aerogel formation requires a critical threshold of Fe x C y  > 160 mg/m 3 , but is surprisingly independent of the initial catalyst diameter or number concentration. The robustness of the critical catalyst mass concentration principle is proved further by producing CNTs using alternative catalyst systems; Fe nanoparticles from a plasma spark generator and cobaltocene and nickelocene precursors. This finding provides evidence that low-cost and high throughput CNT aerogel routes may be achieved by decoupled and enhanced catalyst production and control, opening up new possibilities for large-scale CNT synthesis.

  2. 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.)

  3. 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

  4. Evaluating the Performance of the Mixture Model Coupled with High and Low Reynolds Turbulence Closures in the Numerical Description of Concentrated Solid-Liquid Flows of Settling Particles

    Directory of Open Access Journals (Sweden)

    R. Silva

    2015-12-01

    Full Text Available In this manuscript, Computational Fluid Dynamics (CFD studies applying the Mixture Model coupled with both a High Reynolds and a Low Reynolds k-ε turbulence closures, were used to describe experimental pressure gradients and particle concentration profiles from the literature, for concentrated solid-liquid flows of settling particles in a horizontal pipe above the critical deposition velocity. With this work a new Mixture Model formulation is presented, incorporating the Jones-Launder Low Reynolds k-ε turbulence closure, to overcome the excessive turbulence production observed in the numerical studies using the High Reynolds k-ε turbulence model. Additionally, this formulation provides a more accurate representation of the wall turbulence damping phenomena, observed in the experimental testing for the flow of higher particle concentrations suspensions and higher flow velocities. Knowledge on the conditions that cause turbulence attenuation on solid-liquid flows is still scarce in the literature and of considerable value for industrial applications.

  5. Modifications of exposure to ambient particulate matter: Tackling bias in using ambient concentration as surrogate with particle infiltration factor and ambient exposure factor.

    Science.gov (United States)

    Shi, Shanshan; Chen, Chen; Zhao, Bin

    2017-01-01

    Numerous epidemiological studies explored health risks attributed to outdoor particle pollution. However, a number of these studies routinely utilized ambient concentration as a surrogate for personal exposure to ambient particles. This simplification ignored the difference between indoor and outdoor concentrations of outdoor originated particles and may bias the estimate of particle-health associations. Intending to avoid the bias, particle infiltration factor (F inf ), which describes the penetration of outdoor particles in indoor environment, and ambient exposure factor (α), which represents the fraction of outdoor particles people are truly exposed to, are utilized as modification factors to modify outdoor particle concentration. In this study, the probabilistic distributions of annually-averaged and seasonally-averaged F inf and α were assessed for residences and residents in Beijing. F inf of a single residence and α of an individual was estimated based on the mechanisms governing particle outdoor-to-indoor migration and human time-activity pattern. With this as the core deterministic model, probabilistic distributions of F inf and α were estimated via Monte Carlo Simulation. Annually-averaged F inf of PM 2.5 and PM 10 for residences in Beijing tended to be log-normally distributed as lnN(-0.74,0.14) and lnN(-0.94,0.15) with geometric mean value as 0.47 and 0.39, respectively. Annually-averaged α of PM 2.5 and PM 10 for Beijing residents also tended to be log-normally distributed as lnN(-0.59,0.12) and lnN(-0.73,0.13) with geometric mean value as 0.55 and 0.48, respectively. As for seasonally-averaged results, F inf and α of PM 2.5 and PM 10 were largest in summer and smallest in winter. The obvious difference between these modification factors and unity suggested that modifications of ambient particle concentration need to be considered in epidemiological studies to avoid misclassifications of personal exposure to ambient particles. Moreover

  6. 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...

  7. 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

    Suspension of wear particles in gear oil with respect to the diversity of particle size combined with filter mechanisms has been analyzed. Coupling of wear modes from tribology is combined with particle size bins to show how a mathematical model can be expanded to include information gained from...... 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...... operation. Limitations to the model in lack of fitting to large and frequent signal spikes are suggested to be caused by measurement equipment and/or model constraints. Predicting the transition from quasi-stationary (normal) mode to break-down mode is made possible by particle quantity detection as well...

  8. 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.

  9. Controlling the optical properties of polyaniline doped by boric acid particles by changing their doping agent and initiator concentration

    Science.gov (United States)

    Cabuk, Mehmet; Gündüz, Bayram

    2017-12-01

    In this study, polyaniline doped by boric acid (PAni:BA) conducting polymers were chemically synthesized by oxidative polymerization method using (NH4)2S208 (APS) as initiator. Pani:BA conducting polymers were synthesized by using two different APS/aniline molar ratios as 1:1 and 2:1. Their results were compared with PAni doped by HCl (PAni) conducting polymer. Structural properties of the PAni, PAni:BA (1:1) and PAni:BA (2:1) conducting polymers were characterized by using FTIR, SEM, TGA, particle size and apparent density measurements. Effects of doping agents and initiator concentrations on optical properties were investigated in detail. The optoelectronic parameters such as absorption band edge, molar extinction coefficient, direct allowed band gap, refractive index, optical conductance and electrical conductance of the PAni, PAni:BA (1:1) and PAni:BA (2:1) were determined. The absorption band edge and direct allowed band gap of PAni were decreased with doping BA and increasing APS ratio. Also, the refractive index values of the materials were calculated from experimental results and compared with obtained results from Moss, Ravindra, Herve-Vandamme, Reddy and Kumar-Singh relations.

  10. 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

  11. 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. Copyright © 2010 Elsevier Ltd. All rights reserved.

  12. 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.

  13. 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)

    Pinto Neto, A.

    1987-01-01

    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.) [pt

  14. 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.

  15. Final Technical Report: Using Solid Particles as Heat Transfer Fluid for use in Concentrating Solar Power (CSP) Plants

    Energy Technology Data Exchange (ETDEWEB)

    Lattanzi, Aaron [Univ. of Colorado, Boulder, CO (United States); Hrenya, Christine [Univ. of Colorado, Boulder, CO (United States)

    2016-03-31

    In today’s industrial economy, energy consumption has never been higher. Over the last 15 years the US alone has consumed an average of nearly 100 quadrillion BTUs per year [21]. A need for clean and renewable energy sources has become quite apparent. The SunShot Initiative is an ambitious effort taken on by the United States Department of Energy that targets the development of solar energy that is cost-competitive with other methods for generating electricity. Specifically, this work is concerned with the development of concentrating solar power plants (CSPs) with granular media as the heat transfer fluid (HTF) from the solar receiver. Unfortunately, the prediction of heat transfer in multiphase flows is not well understood. For this reason, our aim is to fundamentally advance the understanding of multiphase heat transfer, particularly in gas-solid flows, while providing quantitative input for the design of a near black body receiver (NBB) that uses solid grains (like sand) as the HTF. Over the course of this three-year project, a wide variety of contributions have been made to advance the state-of-the art description for non-radiative heat transfer in dense, gas-solid systems. Comparisons between a state-of-the-art continuum heat transfer model and discrete element method (DEM) simulations have been drawn. The results of these comparisons brought to light the limitations of the continuum model due to inherent assumptions in its derivation. A new continuum model was then developed for heat transfer at a solid boundary by rigorously accounting for the most dominant non-radiative heat transfer mechanism (particle-fluid-wall conduction). The new model is shown to be in excellent agreement with DEM data and captures the dependence of heat transfer on particle size, a dependency that previous continuum models were not capable of. DEM and the new continuum model were then employed to model heat transfer in a variety of receiver geometries. The results provided crucial

  16. Effects of biochemical and physical processes on concentrations and size distributions of dimethylaminium and trimethylaminium in atmospheric particles from marginal seas of China to the northwest Pacific Ocean

    Science.gov (United States)

    Hu, Q.; Yao, X.; Qu, K.; Cui, Z.; Gao, H.; Xie, H.

    2017-12-01

    This study aim to assess the effects of concentrations and size distributions of aminium ions in atmospheric particles from offshore to open oceans. Size-segregated dimethylaminium (DMA+) and trimethylaminium (TMA+) in atmospheric particles were measured during March-May, 2014. One cruise was over marginal seas of China, in which the concentrations of DMA+ and TMA+ in PM0.056-10 varied from 0.08 nmol m-3 to 0.43 nmol m-3 and from 0.10 to 0.27 nmol m-3, respectively. The two ions both had good positive correlations with subsurface chlorophyll-a maximum and salinity, respectively. The highest concentrations of (DMA+ + TMA+) were observed during cyanobacteria bloom period which happened in subsurface water. The results implied that the concentrations of DMA+ (TMA+) in marine atmospheric particles might be influenced by phytoplankton quantities and species in subsurface seawater. Another cruise was carried out from marginal seas of China to the northwest Pacific Ocean (NWPO). The concentrations of DMA+ and TMA+ in PM0.056-1.8 varied from 0.19 nmol m-3 to 1.53 nmol m-3 and from 0.57 to 3.85 nmol m-3, respectively. The highest (lowest) concentrations of (DMA+ + TMA+) were observed near the cyclonic (anticyclonic) eddy, indicating that the cyclonic (anticyclonic) eddy with high (low) chlorophyll-a enhanced (suppressed) DMA+ (TMA+) production in atmospheric particles. In addition, the dominant particle modes less than 0.2 μm for DMA+ (TMA+) were observed, ie., 0.13±0.02 μm for DMA+ over marginal seas of China, and 0.08±0.00 μm for TMA+ in NWPO, but if they were emitted via bubble bursting needed to be further researched.

  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. 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

    2016-01-01

    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. PMID:26883558

  19. Simulating ultrafine particle formation in Europe using a regional CTM: Contribution of primary emissions versus secondary formation to aerosol number concentrations

    NARCIS (Netherlands)

    Fountoukis, C.; Riipinen, I.; Denier Van Der Gon, H.A.C.; Charalampidis, P.E.; Pilinis, C.; Wiedensohler, A.; O'Dowd, C.; Putaud, J.P.; Moerman, M.; Pandis, S.N.

    2012-01-01

    A three-dimensional regional chemical transport model (CTM) with detailed aerosol microphysics, PMCAMx-UF, was applied to the European domain to simulate the contribution of direct emissions and secondary formation to total particle number concentrations during May 2008. PMCAMx-UF uses the Dynamic

  20. Effects of Varying Dietary Forage Particle Size in Two Concentrate Levels on Chewing Activity, Ruminal Mat Characteristics, and Passage in Dairy Cows

    NARCIS (Netherlands)

    Zebeli, Q.; Tafaj, M.; Weber, I.; Dijkstra, J.; Steingass, H.; Drochner, W.

    2007-01-01

    The objective of this study was to investigate the effects of varying dietary forage particle size on chewing activity, ruminal mat characteristics, passage, and in situ ruminal and total tract digestion in dairy cows at a low- and high-concentrate inclusion. The experiment was designed as a 4 x 4

  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. Simulating ultrafine particle formation in Europe using a regional CTM: contribution of primary emissions versus secondary formation to aerosol number concentrations

    Directory of Open Access Journals (Sweden)

    C. Fountoukis

    2012-09-01

    Full Text Available A three-dimensional regional chemical transport model (CTM with detailed aerosol microphysics, PMCAMx-UF, was applied to the European domain to simulate the contribution of direct emissions and secondary formation to total particle number concentrations during May 2008. PMCAMx-UF uses the Dynamic Model for Aerosol Nucleation and the Two-Moment Aerosol Sectional (TOMAS algorithm to track both aerosol number and mass concentration using a sectional approach. The model predicts nucleation events that occur over scales of hundreds up to thousands of kilometers especially over the Balkans and Southeast Europe. The model predictions were compared against measurements from 7 sites across Europe. The model reproduces more than 70% of the hourly concentrations of particles larger than 10 nm (N10 within a factor of 2. About half of these particles are predicted to originate from nucleation in the lower troposphere. Regional nucleation is predicted to increase the total particle number concentration by approximately a factor of 3. For particles larger than 100 nm the effect varies from an increase of 20% in the eastern Mediterranean to a decrease of 20% in southern Spain and Portugal resulting in a small average increase of around 1% over the whole domain. Nucleation has a significant effect in the predicted N50 levels (up to a factor of 2 increase mainly in areas where there are condensable vapors to grow the particles to larger sizes. A semi-empirical ternary sulfuric acid-ammonia-water parameterization performs better than the activation or the kinetic parameterizations in reproducing the observations. Reducing emissions of ammonia and sulfur dioxide affects certain parts of the number size distribution.

  3. Shape fabrics of particles in low concentration suspensions: 2D analogue experiments and application to tiling in magma

    Science.gov (United States)

    Arbaret, Laurent; Diot, Hervé; Bouchez, Jean-Luc

    1996-07-01

    Jeffery's equations ascribe a theoretical cyclic nature to the shape fabric of non-interacting rigid particles immersed in a viscous fluid undergoing simple shear flow. This theoretical behaviour is confirmed at 'low' shear strains (γ 5 (first experiment: 134 identical particles) or γ > 1 (second experiment: 178 particles with two size classes), then become stable at 17% (first experiment) and at more than 50% (second experiment) of the population of particles. Due to the contribution of the tiled particles, the shape fabric becomes asymmetrical in its orientation distribution, with a maximum lying above the shear plane. The latter result provides a new shear sense indicator, in addition to the statistical determination of the tiled features. The study also suggests that crystalline fabrics in magmas could be acquired at high melt fractions, i.e. early in the crystallization history of the magma.

  4. Background Material

    DEFF Research Database (Denmark)

    Zandersen, Marianne; Hyytiäinen, Kari; Saraiva, Sofia

    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....

  5. Evaluating Suspended Particles Concentration of the Inside and Outside Air of the Classroom and Its Influencing Factors in Middle schools and High Schools of Yazd

    Directory of Open Access Journals (Sweden)

    MH Ehrampoosh

    2015-11-01

    Full Text Available Abstract Introduction: Airborne pollution in such public environments as schools has adverse health effects on pupils and teachers who spend a noticeable amount of time in the school. Therefore, this study aimed to measure the suspended particles concentration of indoor and outdoor air of Yazd schools as well as to determine the influencing parameters on the pollution intensity. Methods: This analytical cross-sectional study was conducted in 20 middle-schools and high schools of males and females in winter of 2013. The environmental aerosol monitoring device, (HAZ-DUST EPAM5000 model was used to measure the concentration of PM1, PM2.5 and PM10. The study data were analyzed via applying correlation, simple linear regression and means comparison tests. Moreover, the study results were compared with the standards of World health organization(WHO and Environmental Health Organization(EPA. Results: The mean concentration of PM10, PM2.5 and PM1 in indoor class air was reported higher compared to the outdoor air. The indoor and outdoor air quality of schools in terms of Air Quality Index9 (AQI Calculator indicated an average condition for PM10, and an unhealthy condition for PM2.5 in regard with the vulnerable groups. A significant relationship was detected between indoor and outdoor air concentration particles (P<0.05. The mean indoor per outdoor air particles ratio (I/O was 1.68, 1.31, 1.46 respectively for PM10, PM2.5, PM1. Conclusion: The study findings revealed a significant relationship between indoor and outdoor suspended particle concentration demonstrating the particles penetration into the classrooms. Therefore, utilizing appropriate air conditioner systems are regarded effective in order to mitigate indoor class pollution.  

  6. Snow and Ice Particle Sizes and Mass Concentrations at Altitudes Up to 9 km (30,000 ft)

    National Research Council Canada - National Science Library

    Jeck, Richard

    1998-01-01

    About 7600 nautical miles (nm) (14,000 km) of select ice particle measurements over the United States have been compiled into a single, computerized database for use in characterizing ice crystal and snowflake...

  7. Variable production of transparent exopolymeric particles by haploid and diploid life stages of coccolithophores grown under different CO2 concentrations

    NARCIS (Netherlands)

    Pedrotti, M.L.; Fiorini, S.; Kerros, M.E.; Middelburg, J.J.; Gattuso, J.P.

    2012-01-01

    The production of transparent exopolymeric particles (TEP) by the coccolithophores, Emiliania huxleyi, Calcidiscus leptoporus and Syracosphaera pulchra was investigated in batch cultures. The abundance, size spectra and carbon content of TEP were examined during the exponential growth phase of both

  8. 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

  9. Room-temperature storage of microalgae in water-in-oil emulsions: influence of solid particle type and concentration in the oil phase.

    Science.gov (United States)

    Fernández, Lorena; Scher, Herbert; Jeoh, Tina; VanderGheynst, Jean S

    2015-12-01

    Water-in-oil emulsions containing silica nanoparticles (Aerosil R974) have the potential to stabilize microalgae for long-term storage. Studies were completed to determine if smectite clays could be used as an alternative to Aerosil R974. Emulsions were prepared with Aerosil R974, and hectorite and bentonite clays in the continuous phase and Chlorella sorokiniana was added to the aqueous phase to monitor the effects of solid particles on emulsion stability. Biological stability (cell viability) was determined using cell density measurements, and physical stability was measured from water droplet size distributions obtained by light scattering measurements and by examining phase separation over time. Measurements were also made to determine the effects of particles in the oil phase on emulsion viscosity. Particle concentrations greater than 0.25 wt% in the oil phase were required for maintaining physical stability. In emulsions containing 1 wt% solid particles and microalgae, biological stability of cells could be sustained for 340 days, regardless of particle type. At 1 wt% particles in the oil phase, apparent viscosity was 165% greater for samples containing hectorite and bentonite clays compared to samples containing Aerosil R974. The higher viscosity would need to be considered in large-scale production of emulsions for commercial application.

  10. 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. Published by Elsevier B.V.

  11. Background radiation

    International Nuclear Information System (INIS)

    Arnott, D.

    1985-01-01

    The effects of background radiation, whether natural or caused by man's activities, are discussed. The known biological effects of radiation in causing cancers or genetic mutations are explained. The statement that there is a threshold below which there is no risk is examined critically. (U.K.)

  12. Quantitative Correlation between Viscosity of Concentrated MAb Solutions and Particle Size Parameters Obtained from Small-Angle X-ray Scattering.

    Science.gov (United States)

    Fukuda, Masakazu; Moriyama, Chifumi; Yamazaki, Tadao; Imaeda, Yoshimi; Koga, Akiko

    2015-12-01

    To investigate the relationship between viscosity of concentrated MAb solutions and particle size parameters obtained from small-angle X-ray scattering (SAXS). The viscosity of three MAb solutions (MAb1, MAb2, and MAb3; 40-200 mg/mL) was measured by electromagnetically spinning viscometer. The protein interactions of MAb solutions (at 60 mg/mL) was evaluated by SAXS. The phase behavior of 60 mg/mL MAb solutions in a low-salt buffer was observed after 1 week storage at 25°C. The MAb1 solutions exhibited the highest viscosity among the three MAbs in the buffer containing 50 mM NaCl. Viscosity of MAb1 solutions decreased with increasing temperature, increasing salt concentration, and addition of amino acids. Viscosity of MAb1 solutions was lowest in the buffer containing histidine, arginine, and aspartic acid. Particle size parameters obtained from SAXS measurements correlated very well with the viscosity of MAb solutions at 200 mg/mL. MAb1 exhibited liquid-liquid phase separation at a low salt concentration. Simultaneous addition of basic and acidic amino acids effectively suppressed intermolecular attractive interactions and decreased viscosity of MAb1 solutions. SAXS can be performed using a small volume of samples; therefore, the particle size parameters obtained from SAXS at intermediate protein concentration could be used to screen for low viscosity antibodies in the early development stage.

  13. 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.

  14. Effect of H3PO4 Concentration and Particle Size of the Eggshell Used in Laying Hens Fed on Bone and Blood

    Directory of Open Access Journals (Sweden)

    S. Kismiati

    2013-06-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 The objective of this research was to evaluate the effect of H3 PO4 concentrations and particle size of eggshell used in the feed of laying hens on bone and blood profiles. Ninety-six laying hens (Isa Brown strain age 25 weeks were kept in individual battery cage and divided into 8 groups randomly. Group 1 was fed using eggshell with out H3PO4 and particle size of <1 mm (feed 1 , group 2 was fed using eggshell that has been soaked in H3PO4 3% and particle size of <1 mm (feed 2, group 3 were fed using eggshell that has been soaked in H3PO4 4% and particle size of <1 mm (feed 3, group 4 was fed using eggshell that has been soaked in H3PO4 5% and particle size of <1 mm (feed 4, group 5 was fed using eggshell that has been soaked in H3PO4 and particle size of <3 mm (feed 5 , group of 6 was fed using eggshell that has been soaked in H3PO4 3% and particle size of <3 mm (feed 6, group 7 was fed using eggshell that has been soaked in H3PO4 4 % and particle size of <3 mm (feed 7 and a group of 8 was fed using eggshell that has been soaked in H3PO4 5% and particle size of <3 mm (feed 8. A Completely Randomized Design patterns factorial 4 x 2 x 3 was used in this research. Result of this research showed that had no interaction effect (P>0.05 between the H3PO4 concentration and particle size of eggshell on weight, volume, diameter of tibia bone and calcium and phosphorus content of the blood. The concentration of H3PO4 or particles size also had no effect (P>0.05 on all variables. Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font

  15. Measurement of airborne concentrations of tire and road wear particles in urban and rural areas of France, Japan, and the United States

    Science.gov (United States)

    Panko, Julie M.; Chu, Jennifer; Kreider, Marisa L.; Unice, Ken M.

    2013-06-01

    In addition to industrial facilities, fuel combustion, forest fires and dust erosion, exhaust and non-exhaust vehicle emissions are an important source of ambient air respirable particulate matter (PM10). Non-exhaust vehicle emissions are formed from wear particles of vehicle components such as brakes, clutches, chassis and tires. Although the non-exhaust particles are relatively minor contributors to the overall ambient air particulate load, reliable exposure estimates are few. In this study, a global sampling program was conducted to quantify tire and road wear particles (TRWP) in the ambient air in order to understand potential human exposures and the overall contribution of these particles to the PM10. The sampling was conducted in Europe, the United States and Japan and the sampling locations were selected to represent a variety of settings including both rural and urban core; and within each residential, commercial and recreational receptors. The air samples were analyzed using validated chemical markers for rubber polymer based on a pyrolysis technique. Results indicated that TRWP concentrations in the PM10 fraction were low with averages ranging from 0.05 to 0.70 μg m-3, representing an average PM10 contribution of 0.84%. The TRWP concentration in air was associated with traffic load and population density, but the trend was not statistically significant. Further, significant differences across days were not observed. This study provides a robust dataset to understand potential human exposures to airborne TRWP.

  16. TASTRAK spectroscopy of polonium-210 alpha-particle activity at bone surfaces: Evidence for a concentrated surface deposit less than 3 μm deep

    International Nuclear Information System (INIS)

    Salmon, P.L.; Henshaw, D.L.; Keitch, P.A.; Allen, J.E.; Fews, A.P.

    1994-01-01

    The technique of α-particle spectroscopy by CR-39 type TASTRAK plastic has been used to study the depth distribution of natural α-particle emitters at the surface of human bone. The predominant component of this α-particle activity was 210 Po supported by 210 Pb, although a smaller activity of 226 Ra was also detected. Autopsy samples of human femur and cranium were obtained from subjects age 63 to 86. Both cortical and trabecular surfaces were analyzed. The results indicate that 210 Pb-supported 210 Po is concentrated at the surfaces of human bone from elderly subjects, in a narrow band 3 μm deep or less, by a factor of about four. As a result, the α-particle dose to the nuclei of cells lining bone surfaces is around 1.8 times greater than that calculated for a uniform volume distribution. Polonium-210 activity indicates the distribution of 210 Pb, and of stable lead, received by continuous intake throughout life at a very low level. A persistent bone surface concentration of lead and other osteotropic metals may be associated with the hypermineralized layer about 1 μm thick which occurs at the surface of resting bone mineral. 31 refs., 9 figs., 3 tabs

  17. Aerosol particle number concentration measurements in five European cities using TSI-3022 condensation particle counter over a three-year period during health effects of air pollution on susceptible subpopulations.

    Science.gov (United States)

    Aalto, Pasi; Hämeri, Kaarle; Paatero, Pentti; Kulmala, Markku; Bellander, Tom; Berglind, Niklas; Bouso, Laura; Castaño-Vinyals, Gemma; Sunyer, Jordi; Cattani, Giorgio; Marconi, Achille; Cyrys, Josef; von Klot, Stephanie; Peters, Annette; Zetzsche, Katrin; Lanki, Timo; Pekkanen, Juha; Nyberg, Fredrik; Sjövall, Billy; Forastiere, Francesco

    2005-08-01

    In this study, long-term aerosol particle total number concentration measurements in five metropolitan areas across Europe are presented. The measurements have been carried out in Augsburg, Barcelona, Helsinki, Rome, and Stockholm using the same instrument, a condensation particle counter (TSI model 3022). The results show that in all of the studied cities, the winter concentrations are higher than the summer concentrations. In Helsinki and in Stockholm, winter concentrations are higher by a factor of two and in Augsburg almost by a factor of three compared with summer months. The winter maximum of the monthly average concentrations in these cities is between 10,000 cm(-3) and 20,000 cm(-3), whereas the summer min is approximately 5000-6000 cm(-3). In Rome and in Barcelona, the winters are more polluted compared with summers by as much as a factor of 4-10. The winter maximum in both Rome and Barcelona is close to 100,000 cm(-3), whereas the summer minimum is > 10,000 cm(-3). During the weekdays the maximum of the hourly average concentrations in all of the cities is detected during the morning hours between 7 and 10 a.m. The evening maxima were present in Barcelona, Rome, and Augsburg, but these were not as pronounced as the morning ones. The daily maxima in Helsinki and Stockholm are close or even lower than the daily minima in the more polluted cities. The concentrations between these two groups of cities are different with a factor of about five during the whole day. The study pointed out the influence of the selection of the measurement site and the configuration of the sampling line on the observed concentrations.

  18. 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)

    Stevens, C.M.; Sepanski; Morris, L.J.

    1995-03-01

    Atmospheric methane (CH 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 2 at present day concentrations (Shine et al. 1990). The causes of the increase of atmospheric CH 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 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 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

  19. N-3 polyunsaturated fatty acids improve lipoprotein particle size and concentration in Japanese patients with type 2 diabetes and hypertriglyceridemia: a pilot study.

    Science.gov (United States)

    Ide, Kana; Koshizaka, Masaya; Tokuyama, Hirotake; Tokuyama, Takahiko; Ishikawa, Takahiro; Maezawa, Yoshiro; Takemoto, Minoru; Yokote, Koutaro

    2018-03-15

    Patients with type 2 diabetes are at high risk for cardiovascular disease. Although hydroxymethylglutaryl-CoA reductase inhibitors (statins) can reduce cardiovascular events, residual risk remains even after target low-density lipoprotein cholesterol (LDL-C) levels have been achieved. Lipoprotein particle size and fraction changes are thought to contribute to such risks. The purpose of this study was to evaluate the effects of n-3 polyunsaturated fatty acids (n-3 PUFAs), predominantly eicosapentaenoic acid and docosahexaenoic acid, on lipoprotein particle size, concentration, and glycemic control in Japanese patients with type 2 diabetes and hypertriglyceridemia. This was a multicenter, prospective, open-label, single arm study. We enrolled 14 patients with type 2 diabetes and hypertriglyceridemia treated with statins and dipeptidyl peptidase-4 inhibitors with glycated hemoglobin (HbA1c) n-3 PUFAs for 12 weeks. Lipoprotein particle sizes, concentrations, lipoprotein insulin resistance (LPIR) scores, lipid profiles, HbA1c, and fasting plasma glucose (FPG) were measured before and after treatment. Lipoprotein profiles were measured by nuclear magnetic resonance spectroscopy. Data were analyzed using Wilcoxon signed-rank tests. Concentrations of total cholesterol (P n-3 PUFA administration. N-3 PUFAs decreased the size of very low-density lipoprotein (VLDL; P N-3 PUFAs partly improved atherogenic lipoprotein particle size and concentration, and produced less atherogenic lipoprotein subclass ratios in patients that achieved target LDL-C levels and glycemic control. These results suggest that n-3 PUFAs may reduce residual cardiovascular risk factors in statin-treated patients with type 2 diabetes and hypertriglyceridemia. The study was registered at UMIN-ID: UMIN000013776 .

  20. A study of the diffusion dynamics and concentration distribution of gold nanospheres (GNSs) without fluorescent labeling inside live cells using fluorescence single particle spectroscopy.

    Science.gov (United States)

    Liu, Fangchao; Dong, Chaoqing; Ren, Jicun

    2018-03-15

    Colloidal gold nanospheres (GNSs) have become important nanomaterials in biomedical applications due to their special optical properties, good chemical stability, and biocompatibility. However, measuring the diffusion coefficients or concentration distribution of GNSs within live cells accurately without any extra fluorescent labeling in situ has still not been resolved. In this work, a single particle method is developed to study the concentration distribution of folic acid-modified GNSs (FA-GNSs) internalized via folate receptors, and investigates their diffusion dynamics within live cells using single particle fluorescence correlation spectroscopy (FCS). We optimized the experimental conditions and verified the feasibility of 30 nm GNSs without extra fluorescence labeling being used for single particle detection inside live cells. Then, the FCS characterization strategy was used to measure the concentration and diffusion coefficient distributions of GNSs inside live cells and the obtained results were basically in agreement with those obtained by TEM. The results demonstrate that our strategy is characterized as an in situ, nondestructive, rapid and dynamic method for the assay of live cells, and it may be widely used in the further design of GNP-based drug delivery and therapeutics.

  1. Ultrafine particles

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Weschler, Charles J.; Wierzbicka, Aneta

    2013-01-01

    Particle number (PN) concentrations (10-300 nm in size) were continuously measured over a period of ∼45 h in 56 residences of nonsmokers in Copenhagen, Denmark. The highest concentrations were measured when occupants were present and awake (geometric mean, GM: 22.3 × 103 cm-3), the lowest when...... the homes were vacant (GM: 6.1 × 103 cm-3) or the occupants were asleep (GM: 5.1 × 103 cm-3). Diary entries regarding occupancy and particle related activities were used to identify source events and apportion the daily integrated exposure among sources. Source events clearly resulted in increased PN...... concentrations and decreased average particle diameter. For a given event, elevated particle concentrations persisted for several hours after the emission of fresh particles ceased. The residential daily integrated PN exposure in the 56 homes ranged between 37 × 103 and 6.0 × 106 particles per cm3·h/day (GM: 3...

  2. Cosmic Tachyon Background Radiation

    CERN Document Server

    Tomaschitz, R

    1999-01-01

    The equilibrium statistical mechanics of a background radiation of superluminal particles is investigated, based on a vectorial wave equation for tachyons of the Proca type. The partition function, the spectral energy density, and the various thermodynamic variables of an ideal Bose gas of tachyons in an open Robertson-Walker cosmology are derived. The negative mass square in the wave equation changes the frequency scaling in the Rayleigh-Jeans law, and there are also significant changes in the low temperature regime as compared to the microwave background, in particular in the caloric and thermal equations of state.

  3. 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.

  4. One year record of bioaerosols and particles concentration in Indo-Gangetic Plain: Implications of biomass burning emissions to high-level of endotoxin exposure.

    Science.gov (United States)

    Rajput, Prashant; Anjum, Manzar Hussain; Gupta, Tarun

    2017-05-01

    Previous studies worldwide have suggested the potential role of bioaerosols as ice-nuclei and cloud-condensation nuclei. Furthermore, their participation in regulating the global carbon cycle urges systematic studies from different environmental conditions throughout the globe. Towards this through one-year study, conducted from June 2015-May 2016, we report on atmospheric abundance and variability of viable bioaerosols, organic carbon (OC) and particles number and deduced mass concentrations from Indo-Gangetic Plain (IGP; at Kanpur). Among viable bioaerosols, the highest concentrations of Gram-positive bacteria (GPB), Gram-negative bacteria (GNB) and Fungi were recorded during December-January (Avg.: 189 CFU/m 3 ), November (244 CFU/m 3 ) and September months (188 CFU/m 3 ), respectively. Annual average concentration of GPB, GNB and Fungi were 105 ± 58, 144 ± 82 and 116 ± 51 CFU/m 3 . Particle number concentration (PNC) associated with fine-fraction aerosols (FFA) predominates throughout the year. However, mineral dust (coarser particle) remains a perennial constituent of atmospheric aerosols over the IGP. Temporal variability records and significant positive linear relationship (p meteorological parameters on viable bioaerosols abundance has been rigorously investigated herein. Accordingly, ambient temperature seems to be more affecting the bacteria (anti-correlation), whereas wet-precipitation (1-4 mm) relates to higher abundance of Fungi. High abundance of GNB during large-scale biomass burning emissions has implications to endotoxin exposure on human health. Field-based data-set of bioaerosols, OC, PNC and deduced mass concentrations reported herein could serve to better constraint their role in human health and climate relevance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Heavy metal concentrations in particle size fractions from street dust of Murcia (Spain) as the basis for risk assessment

    NARCIS (Netherlands)

    Acosta, J.A.; Faz, A.; Kalbitz, K.; Jansen, B.; Martínez-Martínez, S.

    2011-01-01

    Street dust has been sampled from six different types of land use of the city of Murcia (Spain). The samples were fractionated into eleven particle size fractions (<2, 2-10, 10-20, 20-50, 50-75, 75-106, 106-150, 150-180, 180-425, 425-850 μm and 850-2000 μm) and analyzed for Pb, Cu, Zn and Cd. The

  6. 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.

  7. Towards a highly-efficient fuel-cell catalyst: optimization of Pt particle size, supports and surface-oxygen group concentration.

    Science.gov (United States)

    Muthuswamy, Navaneethan; de la Fuente, Jose Luis Gomez; Ochal, Piotr; Giri, Rajiv; Raaen, Steinar; Sunde, Svein; Rønning, Magnus; Chen, De

    2013-03-21

    In the present work, methanol oxidation reaction was investigated on Pt particles of various diameters on carbon-nanofibers and carbon-black supports with different surface-oxygen concentrations, aiming for a better understanding of the relationship between the catalyst properties and the electrochemical performance. The pre-synthesized Pt nanoparticles in ethylene glycol, prepared by the polyol method without using any capping agents, were deposited on different carbon supports. Removal of oxygen-groups from the carbon supports had profound positive effects on not only the Pt dispersion but also the specific activity. The edge structures on the stacked graphene sheets in the platelet carbon-nanofibers provided a strong interaction with the Pt particles, significantly reconstructing them in the process. Such reconstruction resulted in the formation of more plated Pt particles on the CNF than on the carbon-black and exposure of more Pt atoms with relatively high co-ordination numbers, and thereby higher specific activity. Owing to the combined advantages of optimum Pt particle diameter, an oxygen-free surface and the unique properties of CNFs, Pt supported on heat-treated CNFs exhibited a higher mass activity twice of that of its commercial counterpart.

  8. Determination of concentration levels of arsenic, gold and antimony in particle-size fractions of gold ore using Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Nyarku, M.

    2009-02-01

    Instrumental Neutron Activation Analysis (INAA) has been used to quantify the concentrations of arsenic, gold and antimony in particle-size fractions of a gold ore. The ore, which was taken from the Ahafo project site of Newmont Ghana Gold Ltd, was first fractionated into fourteen (14) particle-size fractions using state-of-the-art analytical sieve machine. The minimum sieve mesh size used was 36 microns and grains >2000 microns were not considered for analysis. Results of the sieving were analysed with easysieve software. The < 36 microns sub fraction was found to be the optimum, hosting bulk of all three elements. For arsenic, the element was found to be highly concentrated in < 36 to +100 microns size fractions and erratically distributed from +150 microns fraction and above. For gold, in exception of the sub fraction <36 which had exceptionally high concentration, the element is distributed in all the size fractions but slightly 'plays out' in the +150 to +400 microns fractions. Antimony occurrence in the sample was relatively high in <36 microns size fraction followed by 600 - 800, 800 - 1000, 400 - 600 and 36 - 40 microns size fractions in that order. Gold content in the sample was far higher than that of arsenic and antimony. Gold concentration in the composite sample was in the range 564 - 8420 ppm. Arsenic levels were higher as compared to antimony. The range of arsenic concentration in the composite sample was 14.33 - 186.92 ppm. Antimony concentration was in the range 1.09 - 9.48 ppm. (au)

  9. The role of fuel concentration on particle size and dielectric properties of manganese substituted zinc ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ranjith Kumar, E., E-mail: ranjueaswar@gmail.com; Jayaprakash, R.

    2014-10-01

    Mn substituted ZnFe{sub 2}O{sub 4} nanoparticles were prepared by the auto-combustion method using different fuel ratios of 50%, 75% and 100%.The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectrum (EDX). Also, the dielectric behaviors of the samples were investigated for different annealing temperatures. The X-ray diffraction patterns indicated that the annealed samples resulted in the formation of crystalline powder and the presence of α-Fe{sub 2}O{sub 3} as a secondary phase. The average crystallite sizes of the samples are from ∼12 to 60 nm. The external morphology and microstructure of the samples are tested by SEM and TEM. The effect of annealing temperature and particle size on dielectric properties such as dielectric constant (έ) and dielectric loss (D) of the spinel Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} nanoparticles was measured using impedance analyzer in the frequency range 100 kHz–5 MHz. - Highlights: • An auto-combustion method support to prepare less size of particles. • The fuel ratio influences the dielectric properties of the samples. • Nature of the ferrites was affected with increasing annealing temperature.

  10. Concentration and chemical composition of PM10 particles in the metropolitan area of ​Costa Rica in 2012

    OpenAIRE

    Jorge Herrera; José F. Rojas; Víctor H. Beita; Agustín Rodríguez; David Solórzano; Hazel Argüello

    2014-01-01

    During 2012 the PM10 concentrations were measured in 13 sampling sites distributed in the metropolitan area of Costa Rica. The samples were collected using high volume samplers and subsequently analyzed for: ions (F-, Cl-, NO2-, NO3-, PO43-, SO42-), trace metals (V, Cr, Cu, Mn, Fe, Al, Pb, Ni), organic and elemental carbon content. Sampling sites located in high traffic commercial and industrial zones exhibited significative increased concentrations (42 – 29 µg/m3) compared to low traffic com...

  11. 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

    problems. Use of particle filtration units (PFU's) might be an effective way for rapid removal of indoor PM.In a randomised cross-over design, the custom built PFU's ran for two weeks in each of two modes: with or without the inclusion of a HEPA filter.We assessed the association between the concentration...... 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...... concentrations. Furthermore, the winter period and a location farther from a trafficked street were associated with increased PM2.5 mass. Overall, the use of PFU led to a decrease in the concentrations of PM2.5 of 54.5% (median value).We assessed the PFU particle-removal efficiency by using the amount...

  12. Phenology of a Vegetation Barrier and Resulting Impacts on Near-Highway Particle Number and Black Carbon Concentrations on a School Campus

    Directory of Open Access Journals (Sweden)

    Christina H. Fuller

    2017-02-01

    Full Text Available Traffic-related air pollution is a persistent concern especially in urban areas where populations live in close proximity to roadways. Innovative solutions are needed to minimize human exposure and the installation of vegetative barriers shows potential as a method to reduce near-road concentrations. This study investigates the impact of an existing stand of deciduous and evergreen trees on near-road total particle number (PNC and black carbon (BC concentrations across three seasons. Measurements were taken during spring, fall and winter on the campus of a middle school in the Atlanta (GA, USA area at distances of 10 m and 50 m from a major interstate highway. We identified consistent decreases in BC concentrations, but not for PNC, with increased distance from the highway. In multivariable models, hour of day, downwind conditions, distance to highway, temperature and relative humidity significantly predicted pollutant concentrations. The magnitude of effect of these variables differed by season, however, we were not able to show a definitive impact of the vegetative barrier on near-road concentrations. More detailed studies are necessary to further examine the specific configurations and scenarios that may produce pollutant and exposure reductions.

  13. Assessing Single Particle Soot Photometer and Integrating Sphere/Integrating Sandwich Spectrophotometer measurement techniques for quantifying black carbon concentration in snow

    Directory of Open Access Journals (Sweden)

    J. P. Schwarz

    2012-11-01

    Full Text Available We evaluate the performance of the Single Particle Soot Photometer (SP2 and the Integrating Sphere/Integrating Sandwich Spectrophotometer (ISSW in quantifying the concentration of refractory black carbon (BC in snow samples. We find that the SP2 can be used to measure BC mass concentration in snow with substantially larger uncertainty (60% than for atmospheric sampling (<30%. Achieving this level of accuracy requires careful assessment of nebulizer performance and SP2 calibration with consideration of the fact that BC in snow can exist in larger sizes than typically observed in the atmosphere. Once these issues are addressed, the SP2 is able to measure the size distribution and mass concentration of BC in the snow. Laboratory comparison of the SP2 and the ISSW revealed significant biases in the estimate of BC concentration from the ISSW when test samples contained dust or non-absorbing particulates. These results suggest that current estimates of BC mass concentration in snow or ice formed from fallen snow using either the SP2 or the ISSW may be associated with significant underestimates of uncertainty.

  14. Suspended particulate matter in New York City: element concentrations as a function of particle size and elevation above street

    International Nuclear Information System (INIS)

    Bauman, S.E.; Williams, E.T.; Finston, H.L.; Bond, A.H. Jr.; Lesser, P.M.S.; Ferrand, E.F.

    1977-01-01

    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 SO 2 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

  15. Estimating Hourly Concentrations of PM2.5 across a Metropolitan Area Using Low-Cost Particle Monitors

    Directory of Open Access Journals (Sweden)

    Nadezda Zikova

    2017-08-01

    Full Text Available There is concern regarding the heterogeneity of exposure to airborne particulate matter (PM across urban areas leading to negatively biased health effects models. New, low-cost sensors now permit continuous and simultaneous measurements to be made in multiple locations. Measurements of ambient PM were made from October to April 2015–2016 and 2016–2017 to assess the spatial and temporal variability in PM and the relative importance of traffic and wood smoke to outdoor PM concentrations in Rochester, NY, USA. In general, there was moderate spatial inhomogeneity, as indicated by multiple pairwise measures including coefficient of divergence and signed rank tests of the value distributions. Pearson correlation coefficients were often moderate (~50% of units showed correlations >0.5 during the first season, indicating that there was some coherent variation across the area, likely driven by a combination of meteorological conditions (wind speed, direction, and mixed layer heights and the concentration of PM2.5 being transported into the region. Although the accuracy of these PM sensors is limited, they are sufficiently precise relative to one another and to research grade instruments that they can be useful is assessing the spatial and temporal variations across an area and provide concentration estimates based on higher-quality central site monitoring data.

  16. Fluctuations of the number of adsorbed micro/nanoparticles in sensors for measurement of particle concentration in air and liquid environments

    Directory of Open Access Journals (Sweden)

    Jokić Ivana

    2015-01-01

    Full Text Available A theoretical model of fluctuations of the number of adsorbed micro/nanoparticles in environmental sensors operating in air and liquids is presented, taking into account the effects of the mass transfer processes of the target particles in a sensor reaction chamber. The expressions for the total power of the corresponding adsorption-desorption noise, and for the corresponding signal-to-noise ratio are also derived. The presented analysis shows that the transfer processes can have a significant influence on the sensors limiting performance. The influence on both the fluctuations spectrum and the signal-to-noise ratio is estimated at different values of target particles concentration, functionalization sites surface density, and adsorption and desorption rate constants (the values are chosen from the ranges corresponding to real conditions. The analysis provides the guidelines for optimization of sensor design and operating conditions for the given target substance and sensor functionalization, in order to decrease the influence of the mass transfer, thus improving the ultimate performance (e.g. minimal detectable signal, signal-to-noise ratio of sensors for particle detection. The calculations we performed show that it is possible to increase the signal-to-noise ratio for as much as two orders of magnitude by using the optimization that eliminates the mass transfer influence. [Projekat Ministarstva nauke Republike Srbije, br. TR32008

  17. Occurrence of high concentrations of a unique degradation product of chlorophyll-a in particles residing below the thermocline throughout a period of oxygen depletion in Lake Kinneret

    Directory of Open Access Journals (Sweden)

    Helen M. TALBOT

    2001-08-01

    Full Text Available An unrecognized chlorophyllous pigment, designated Pheob4, was the most abundant degradation product of chlorophyll-a (Chla in the hypolimimnion, benthic boundary layer and sedimenting particles in Lake Kinneret in June-July 1997, when a prolonged period of residual oxygen concentration was found below the thermocline. The highest concentration of Pheob4 was found in the benthic boundary layer, where it reached as high concentration as 2 μg l-1. In sediment traps positioned below the thermocline Pheob4 constituted from about 5 to 20% of the Chl-a concentration and in bottom sediments from 5 to 185%. Pheob4 was not detected in epilimnetic water samples, but was found in sediment traps located within the oxygenated water column, within the range of surface wave action. Comparison of regular traps, with traps poisoned by formaldehyde indicates that the importance of Pheob4- containing particles in the sedimentation flux is relatively low, and that the bulk of Pheob4 found in the bottom sediment is apparently a result of Chl-a transformation in situ by biological activity. The timing and location of Pheob4 appearance coincided with the lake compartments where denitrification apparently took place. This suggests that Pheob4 may be used as a target pigment to trace organic matter processing under transient conditions in the water column and on the bottom sediments. Pheob4 was tentatively identified as 132, 172 cyclophaeophorbide-a enol. But, since the identification was done on a different system than the one used for the analysis of most of the samples, further investigation is required to verify that finding.

  18. Magnetic ferrite particles combined with electrothermal atomic absorption spectrometry for the speciation of low concentrations of arsenic.

    Science.gov (United States)

    López-García, Ignacio; Marín-Hernández, Juan José; Hernández-Córdoba, Manuel

    2018-05-01

    Freshly in situ prepared ferrite particles were used for the micro-solid phase extraction of arsenic species. When the separation was carried out at pH 8, inorganic arsenic (As(III) + As(V)) and monomethylarsonic acid (MMA) were retained in the magnetic material. A second aliquot was treated with 2,3 dimercapto propanol, leading to the retention of As(V)+MMA, while a third aliquot was first treated with sodium thiosulphate, in which case only inorganic arsenic passed to the solid phase. In all cases, the solid residue collected by a magnet was suspended in a dilute nitric acid solution containing Triton X-100 and introduced into the electrothermal atomizer to obtain the analytical signal of arsenic. The use of palladium as a chemical modifier allowed calibration to be carried out with aqueous standards. The detection limit was 0.02µgL -1 arsenic for a 10mL sample volume. The procedure was applied to waters and herbal infusions, and its reliability was evaluated by analyzing eleven certified reference materials for which speciation data are provided. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Comparative measurements of ambient atmospheric concentrations of ice nucleating particles using multiple immersion freezing methods and a continuous flow diffusion chamber

    Science.gov (United States)

    DeMott, Paul J.; Hill, Thomas C. J.; Petters, Markus D.; Bertram, Allan K.; Tobo, Yutaka; Mason, Ryan H.; Suski, Kaitlyn J.; McCluskey, Christina S.; Levin, Ezra J. T.; Schill, Gregory P.; Boose, Yvonne; Rauker, Anne Marie; Miller, Anna J.; Zaragoza, Jake; Rocci, Katherine; Rothfuss, Nicholas E.; Taylor, Hans P.; Hader, John D.; Chou, Cedric; Huffman, J. Alex; Pöschl, Ulrich; Prenni, Anthony J.; Kreidenweis, Sonia M.

    2017-09-01

    A number of new measurement methods for ice nucleating particles (INPs) have been introduced in recent years, and it is important to address how these methods compare. Laboratory comparisons of instruments sampling major INP types are common, but few comparisons have occurred for ambient aerosol measurements exploring the utility, consistency and complementarity of different methods to cover the large dynamic range of INP concentrations that exists in the atmosphere. In this study, we assess the comparability of four offline immersion freezing measurement methods (Colorado State University ice spectrometer, IS; North Carolina State University cold stage, CS; National Institute for Polar Research Cryogenic Refrigerator Applied to Freezing Test, CRAFT; University of British Columbia micro-orifice uniform deposit impactor-droplet freezing technique, MOUDI-DFT) and an online method (continuous flow diffusion chamber, CFDC) used in a manner deemed to promote/maximize immersion freezing, for the detection of INPs in ambient aerosols at different locations and in different sampling scenarios. We also investigated the comparability of different aerosol collection methods used with offline immersion freezing instruments. Excellent agreement between all methods could be obtained for several cases of co-sampling with perfect temporal overlap. Even for sampling periods that were not fully equivalent, the deviations between atmospheric INP number concentrations measured with different methods were mostly less than 1 order of magnitude. In some cases, however, the deviations were larger and not explicable without sampling and measurement artifacts. Overall, the immersion freezing methods seem to effectively capture INPs that activate as single particles in the modestly supercooled temperature regime (> -20 °C), although more comparisons are needed in this temperature regime that is difficult to access with online methods. Relative to the CFDC method, three immersion freezing

  20. Experimental study of the response functions of direct-reading instruments measuring surface-area concentration of airborne nanostructured particles

    Science.gov (United States)

    Bau, Sébastien; Witschger, Olivier; Gensdarmes, François; Thomas, Dominique

    2009-05-01

    An increasing number of experimental and theoretical studies focus on airborne nanoparticles (NP) in relation with many aspects of risk assessment to move forward our understanding of the hazards, the actual exposures in the workplace, and the limits of engineering controls and personal protective equipment with regard to NP. As a consequence, generating airborne NP with controlled properties constitutes an important challenge. In parallel, toxicological studies have been carried out, and most of them support the concept that surface-area could be a relevant metric for characterizing exposure to airborne NP [1]. To provide NP surface-area concentration measurements, some direct-reading instruments have been designed, based on attachment rate of unipolar ions to NP by diffusion. However, very few information is available concerning the performances of these instruments and the parameters that could affect their responses. In this context, our work aims at characterizing the actual available instruments providing airborne NP surface-area concentration. The instruments (a- LQ1-DC, Matter Engineering; b-AeroTrak™ 9000, TSI; c- NSAM, TSI model 3550;) are thought to be relevant for further workplace exposure characterization and monitoring. To achieve our work, an experimental facility (named CAIMAN) was specially designed, built and characterized.

  1. Concentration and chemical composition of PM10 particles in the metropolitan area of ​Costa Rica in 2012

    Directory of Open Access Journals (Sweden)

    Jorge Herrera

    2014-12-01

    Full Text Available During 2012 the PM10 concentrations were measured in 13 sampling sites distributed in the metropolitan area of Costa Rica. The samples were collected using high volume samplers and subsequently analyzed for: ions (F-, Cl-, NO2-, NO3-, PO43-, SO42-, trace metals (V, Cr, Cu, Mn, Fe, Al, Pb, Ni, organic and elemental carbon content. Sampling sites located in high traffic commercial and industrial zones exhibited significative increased concentrations (42 – 29 µg/m3 compared to low traffic commercial and residential zones (23 – 15 µg/m3. As for speciation, crustal contribution increases from 13-14 % found in high traffic industrial zones to 28 % in residential zones. While marine aerosol contribution ranges from 2,5 to 5% for all sampling sites without a distinctive pattern. The OC and EC fraction was the most important contribution to the PM10 composition, mainly in HE-01 and BE-01 sampling sites accounting for around 53 and 56 % of the total mass. This reflects the importance of combustion sources to the fine particulate matter composition. In the case of the trace metals fraction it was the lowest one found for all the sampling sites.

  2. Experimental study of the response functions of direct-reading instruments measuring surface-area concentration of airborne nanostructured particles

    Energy Technology Data Exchange (ETDEWEB)

    Bau, Sebastien; Witschger, Olivier [Institut National de Recherche et de Securite, INRS, Laboratoire de Metrologie des Aerosols, Rue du Morvan, CS 60027, 54519 Vandoeuvre Cedex (France); Gensdarmes, Francois [Institut de Radioprotection et de Surete Nucleaire, IRSN, Laboratoire de Physique et de Metrologie des Aerosols, BP 68, 91192 Gif-sur-Yvette Cedex (France); Thomas, Dominique [Laboratoire des Sciences du Genie Chimique, LSGC/CNRS, Nancy Universite, BP 2041, 54001 Nancy Cedex (France)], E-mail: sebastien.bau@inrs.fr

    2009-05-01

    An increasing number of experimental and theoretical studies focus on airborne nanoparticles (NP) in relation with many aspects of risk assessment to move forward our understanding of the hazards, the actual exposures in the workplace, and the limits of engineering controls and personal protective equipment with regard to NP. As a consequence, generating airborne NP with controlled properties constitutes an important challenge. In parallel, toxicological studies have been carried out, and most of them support the concept that surface-area could be a relevant metric for characterizing exposure to airborne NP. To provide NP surface-area concentration measurements, some direct-reading instruments have been designed, based on attachment rate of unipolar ions to NP by diffusion. However, very few information is available concerning the performances of these instruments and the parameters that could affect their responses. In this context, our work aims at characterizing the actual available instruments providing airborne NP surface-area concentration. The instruments (a- LQ1-DC, Matter Engineering; b-AeroTrak{sup x2122} 9000, TSI; c- NSAM, TSI model 3550;) are thought to be relevant for further workplace exposure characterization and monitoring. To achieve our work, an experimental facility (named CAIMAN) was specially designed, built and characterized.

  3. 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.

  4. THE DEPENDENCE OF DIELECTRIC PERMEABILITY AND SPECIFIC VOLUME RESISTANCE OF POLYMER COMPOSITES ON THE CONCENTRATION OF NANO-DIMENSIONAL ALUMINIUM PARTICLES AND CARBON BLACK FILLERS

    Directory of Open Access Journals (Sweden)

    A. S. Akhriev

    2017-01-01

    Full Text Available Objectives. The main idea of the present study was the production of polymer composites based on synthetic isoprene elastomer and low-density polyethylene containing nanoparticles of carbon black and aluminium in various amounts.Methods. An exponential approach was used throughout the study to better control the region of small additives; this control was impossible to achieve using a linear distribution of nanofillers among the small additives. The composites were filled with nanosized aluminium and DG-100 carbon black particles with a specific adsorption surface of 100 m2 /g and having an average particle size of 20-30 nm. Electrophysical parameters were measured by conventional techniques of electron microscopy, electron shadow microscopy and hydrostatic weighing. Maxwell-Wagner theory and polarisation model were applied.Results. For a composite containing 80% of isoprene synthetic rubber (SCI-3 and 20% of low-density polyethylene, the dielectric permeability and specific volume resistivity dependences were studied experimentally and their graphs were plotted against the concentration of nanosized particles of aluminium and carbon black fillers. The features of these curves were considered. It is shown that, for small amounts of Al and carbon black nanoparticles in the composite, significant changes (extrema take place on the curves ԑ '= ԑ' (C and ρᵥ = ρᵥ (C, which do not conform to the Maxwell-Wagner polarisation model. For some heterogeneous polymer mixtures, a distribution of carbon black particles was observed that led to a superadditive electrical resistance.Conclusion. It is shown that for small amounts of Al and carbon black nanoparticles in composite materials, significant changes (extrema take place on the curves ԑ '= ԑ' (C and ρᵥ = ρᵥ (C that do not fit within the framework of the Maxwell-Wagner polarisation model.

  5. Consumption of low doses of fat prevents the postprandial rise in chylomicron particle concentration and remnant accumulation in healthy normolipidaemic males

    Science.gov (United States)

    James, Anthony P.; Mamo, John C.

    2012-01-01

    Chylomicron particles are continually synthesised and secreted from the intestine even in the absence of ingested fat. It is possible that following consumption of low doses of fat the basal level of chylomicron secretion and subsequent metabolism are sufficient to metabolise this fat without an increase in postprandial chylomicron concentrations. To test this hypothesis, healthy male subjects were randomised to receive, on three separate occasions, meals containing a range of doses of fat (average 8·1–19 g) and effects on postprandial lipaemia and chylomicron concentration were determined. Furthermore, to delineate the effect on lipid-rich v. lipid-poor (remnant) forms lipid levels were also determined in a density postprandial concentration of chylomicrons was unaltered, whereas following the medium dose postprandial chylomicron concentrations were significantly increased. Interestingly, this increase was only detected in the lipid-rich chylomicron fraction, with postprandial levels of chylomicron remnants remaining unchanged. In conclusion, it appears that consumption of what would be considered low to medium doses of fat are not associated with transient postprandial increases in chylomicron remnants in healthy male subjects. PMID:25191552

  6. 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.

  7. Concentration and size distribution of water-extracted dimethylaminium and trimethylaminium in atmospheric particles during nine campaigns - Implications for sources, phase states and formation pathways.

    Science.gov (United States)

    Xie, Huan; Feng, Limin; Hu, Qingjing; Zhu, Yujiao; Gao, Huiwang; Gao, Yang; Yao, Xiaohong

    2018-03-07

    In this study, we determined the concentrations of water-extracted dimethylaminium (DMA + ) and trimethylaminium (TMA + ) in size-segregated atmospheric particles collected during three inland campaigns and one sea-beach campaign in Qingdao and five marine campaigns in marginal seas of China and the northwest Pacific Ocean. The averages of DMA + and TMA + in PM 0.056 - 10 (the sum of concentrations from 0.056 to 10μm) during each campaign ranged from 0.045 to 1.1nmolm -3 and from 0.029 to 0.53nmolm -3 , respectively. The increased concentrations of DMA + and TMA + in PM 0.056 - 10 , particularly the 1-2 orders of magnitude increased ratios of DMA + /NH 4 + and TMA + /NH 4 + , in the marine and sea-beach atmospheres indicated that the overwhelming majority was derived from marine sources. Size distributions of TMA + and DMA + were also investigated in terms of phase states and formation pathways, e.g., the dominant modes of particulate DMA + and TMA + in some samples were characterized by the mass median aerodynamic diameter at 0.1-0.2μm against the dominant mode of NH 4 + and SO 4 2- at 0.7-0.9μm, while the ratios of DMA + /NH 4 + and/or TMA + /NH 4 + in 0.2μm particles. This strongly implied that the particulate DMA + and TMA + at 0.2μm size range mainly existed in the aqueous (or solid) phase where the dominance of gas-aerosol equilibria would cause the ratios to be almost size-independent. The size-dependent phase states corresponded to their various formation pathways. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. 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.

  9. Nonthermal cosmic neutrino background

    Science.gov (United States)

    Chen, Mu-Chun; Ratz, Michael; Trautner, Andreas

    2015-12-01

    We point out that, for Dirac neutrinos, in addition to the standard thermal cosmic neutrino background (C ν B ), there could also exist a nonthermal neutrino background with comparable number density. As the right-handed components are essentially decoupled from the thermal bath of standard model particles, relic neutrinos with a nonthermal distribution may exist until today. The relic density of the nonthermal (nt) background can be constrained by the usual observational bounds on the effective number of massless degrees of freedom Neff and can be as large as nν nt≲0.5 nγ. In particular, Neff can be larger than 3.046 in the absence of any exotic states. Nonthermal relic neutrinos constitute an irreducible contribution to the detection of the C ν B and, hence, may be discovered by future experiments such as PTOLEMY. We also present a scenario of chaotic inflation in which a nonthermal background can naturally be generated by inflationary preheating. The nonthermal relic neutrinos, thus, may constitute a novel window into the very early Universe.

  10. Empirical correlations to estimate agglomerate size and deposition during injection of a polyelectrolyte-modified Fe0 nanoparticle at high particle concentration in saturated sand.

    Science.gov (United States)

    Phenrat, Tanapon; Kim, Hye-Jin; Fagerlund, Fritjof; Illangasekare, Tissa; Lowry, Gregory V

    2010-11-25

    Controlled emplacement of polyelectrolyte-modified nanoscale zerovalent iron (NZVI) particles at high particle concentration (1-10 g/L) is needed for effective in situ subsurface remediation using NZVI. Deep bed filtration theory cannot be used to estimate the transport and deposition of concentrated polyelectrolyte-modified NZVI dispersions (>0.03 g/L) because particles agglomerate during transport which violates a fundamental assumption of the theory. Here we develop two empirical correlations for estimating the deposition and transport of concentrated polyelectrolyte-modified NZVI dispersions in saturated porous media when NZVI agglomeration in porous media is assumed to reach steady state quickly. The first correlation determines the apparent stable agglomerate size formed during NZVI transport in porous media for a fixed hydrogeochemical condition. The second correlation estimates the attachment efficiency (sticking coefficient) of the stable agglomerates. Both correlations are described using dimensionless numbers derived from parameters affecting deposition and agglomeration in porous media. The exponents for the dimensionless numbers are determined from statistical analysis of breakthrough data for polyelectrolyte-modified NZVI dispersions collected in laboratory scale column experiments for a range of ionic strength (1, 10, and 50mM Na(+) and 0.25, 1, and 1.25 mM Ca(2+)), approach velocity (0.8 to 55 × 10(-4)m/s), average collector sizes (d(50)=99 μm, 300 μm, and 880 μm), and polyelectrolyte surface modifier properties. Attachment efficiency depended on approach velocity and was inversely related to collector size, which is contrary to that predicted from classic filtration models. High ionic strength, the presence of divalent cations, lower extended adsorbed polyelectrolyte layer thickness, decreased approach velocity, and a larger collector size promoted NZVI agglomeration and deposition and thus limited its mobility in porous media. These effects

  11. 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.

  12. Elemental Composition and Concentration of Upstate New York Rainwater Samples Using the Union College Pelletron Particle Accelerator and Proton Induced X-ray Emission (PIXE) Spectroscopy

    Science.gov (United States)

    Schuff, Katie; Labrake, Scott; Vineyard, Michael; Harrington, Charles; Gleason, Colin

    2009-10-01

    A 1-megavolt tandem electrostatic Pelletron particle accelerator housed at Union College was used to measure the elemental composition and concentration of rain water collected in Schenectady, NY in June 2009. A beam of 2.0-MeV protons was directed at an approximately 12-micrometer thin Mylar film substrate onto which 1.0-mL of concentrated rainwater was dried. The interaction of the incident protons with the target material causes inner shell electrons to be ejected and these vacancies are filled through electronic transitions of higher orbital electrons with the production of x-ray photons characteristic of the elemental composition of the target. This is the PIXE Method. Data on the intensity and energy of x-rays were collected using an Amptek silicon drift detector. Spectra of the number of x-rays collected as a function of energy were analyzed and the elemental composition was found to contain Ca, K, S, Cl, Ti, Cr, Fe, Cu, Zn, & Se(added as an internal standard) with concentrations determined using the analysis package GUPIX.

  13. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    Science.gov (United States)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard; Thorborg, Jesper; Tiedje, Niels; Hattel, Jesper

    2018-02-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper. First, a material equivalent to the ductile cast iron matrix is manufactured and subjected to dilatometric and high-temperature tensile tests. Subsequently, a two-scale hierarchical top-down model is devised, calibrated on the basis of the collected data and used to simulate the interaction between the graphite particles and the matrix during manufacturing of the industrial part considered in the XRD study. The model indicates that, besides the viscoplastic deformation of the matrix, the effect of the inelastic deformation of the graphite has to be considered to explain the magnitude of the XRD strain. Moreover, the model shows that the large elastic strain perturbations recorded with XRD close to the graphite-matrix interface are not artifacts due to e.g. sharp gradients in chemical composition, but correspond to residual stress concentrations induced by the conical sectors forming the internal structure of the graphite particles. In contrast to common belief, these results thus suggest that ductile cast iron parts cannot be considered, in general, as stress-free at the microstructural scale.

  14. 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.

  15. On the observation of the need for an unusually high concentration of cysteine and homocysteine to induce aggregation of polymer-stabilized gold nano particles

    Energy Technology Data Exchange (ETDEWEB)

    Radhakumary, C.; Sreenivasan, K., E-mail: sreeni@sctimst.ac.in [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Laboratory for Polymer Analysis, Biomedical Technology Wing (India)

    2013-02-15

    This study reports the interaction of chitosan-stabilized gold nanoparticles (CH-AuNPs) with cysteine (Cys) and homocysteine (Hcys) in aqueous media at pH 1.4. Since the polymer precipitates at higher pH, and the amino acids Cys and HCys are soluble at acidic pH, we kept the pH around 1.4 for stabilizing the particles. Zeta potential of CH-AuNPs was found to be positive and it is reasonable to assume that +ve Cys or Hcys at pH 1.4 will experience repulsive force. However, TEM images and absorption spectra indicated formation of aggregates including rod-like assembly. An interesting observation was the need for unusually high concentration of analytes (Cys and Hcys) to induce the assembly of CH-AuNPs. We also found time bound variation of the optical properties probably indicating the interaction is kinetically controlled and only a fraction of the analyte molecules having sufficient energy can bind onto the particles. We observed that at elevated temperature, the reaction was faster with a lower concentration of Cys or Hcys. These observations were supported by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory which describes the interparticle interaction and the colloidal stability in solution. Only molecules possessing enough energy to cross this force barrier can cause the aggregation. We also noted a time lag between Cys and Hcys to influence optical properties reflecting the possibility of using this simple approach to discriminate these two clinically relevant molecules. Our observation shows that simple sensing as well as generation of novel nanostructures could be manipulated by a judicious choice of conditions such as stabilizing agents, pH, etc.Graphical AbstractMore energetic ones cross the barrier to induce aggregation.

  16. On the observation of the need for an unusually high concentration of cysteine and homocysteine to induce aggregation of polymer-stabilized gold nano particles

    Science.gov (United States)

    Radhakumary, C.; Sreenivasan, K.

    2013-02-01

    This study reports the interaction of chitosan-stabilized gold nanoparticles (CH-AuNPs) with cysteine (Cys) and homocysteine (Hcys) in aqueous media at pH 1.4. Since the polymer precipitates at higher pH, and the amino acids Cys and HCys are soluble at acidic pH, we kept the pH around 1.4 for stabilizing the particles. Zeta potential of CH-AuNPs was found to be positive and it is reasonable to assume that +ve Cys or Hcys at pH 1.4 will experience repulsive force. However, TEM images and absorption spectra indicated formation of aggregates including rod-like assembly. An interesting observation was the need for unusually high concentration of analytes (Cys and Hcys) to induce the assembly of CH-AuNPs. We also found time bound variation of the optical properties probably indicating the interaction is kinetically controlled and only a fraction of the analyte molecules having sufficient energy can bind onto the particles. We observed that at elevated temperature, the reaction was faster with a lower concentration of Cys or Hcys. These observations were supported by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory which describes the interparticle interaction and the colloidal stability in solution. Only molecules possessing enough energy to cross this force barrier can cause the aggregation. We also noted a time lag between Cys and Hcys to influence optical properties reflecting the possibility of using this simple approach to discriminate these two clinically relevant molecules. Our observation shows that simple sensing as well as generation of novel nanostructures could be manipulated by a judicious choice of conditions such as stabilizing agents, pH, etc.

  17. Air mass characteristics, aerosol particle number concentrations, and number size distributions at Macquarie Island during the First Aerosol Characterization Experiment (ACE 1)

    Science.gov (United States)

    Brechtel, Fred J.; Kreidenweis, Sonia M.; Swan, Hilton B.

    1998-01-01

    During the First Aerosol Characterization Experiment (ACE 1), continuous measurements were made of the particle number size distribution (between 18 and 540 nm diameter (Dp)) and total particle number concentration (Dp > 3 nm and Dp > 12 nm) on Macquarie Island, Tasmania (54°30'S, 158°57'E, 7 m above sea level). Periodic real-time measurements of dimethyl sulfide were also made. Sampled air masses were separated into clean marine and those influenced by Tasmania or Antarctica. Observations were compared to those from a southern hemisphere midlatitude site (Cape Grim) and to sites on the Antarctic continent. It was found that the average total number concentration observed during clean marine conditions, 675 cm-3, was about 21% higher than values observed at Cape Grim during ACE 1 and was similar to the high end of the historical range of number concentrations reported by Gras [1995] for Cape Grim during the same time of year. During both clean marine and influenced conditions, the Aitken and accumulation modes dominate the number size distribution, with a Young Aitken mode observed less often. The number size distribution between 18 and 540 nm exhibited two and three modes 75% and 25% of the time, respectively, during clean marine conditions, more consistent with previous observations at Cape Grim than with those from coastal Antarctica. The typical bimodal number distribution at Macquarie Island exhibited average modal diameters of 33 and 113 nm during clean marine conditions, corresponding to the smaller Aitken mode and larger accumulation mode, respectively. The 50 to 70 nm diameter range corresponds to the minimum in the bimodal size distribution at Macquarie Island, except for continentally influenced periods when the size distribution exhibits an Aitken mode near 50 nm and an accumulation mode near 128 nm. The Young Aitken mode appeared most often during or immediately after periods of precipitation associated with both warm and cold fronts, when the Aitken

  18. Responses of Mixed-Phase Cloud Condensates and Cloud Radiative Effects to Ice Nucleating Particle Concentrations in NCAR CAM5 and DOE ACME Climate Models

    Science.gov (United States)

    Liu, X.; Shi, Y.; Wu, M.; Zhang, K.

    2017-12-01

    Mixed-phase clouds frequently observed in the Arctic and mid-latitude storm tracks have the substantial impacts on the surface energy budget, precipitation and climate. In this study, we first implement the two empirical parameterizations (Niemand et al. 2012 and DeMott et al. 2015) of heterogeneous ice nucleation for mixed-phase clouds in the NCAR Community Atmosphere Model Version 5 (CAM5) and DOE Accelerated Climate Model for Energy Version 1 (ACME1). Model simulated ice nucleating particle (INP) concentrations based on Niemand et al. and DeMott et al. are compared with those from the default ice nucleation parameterization based on the classical nucleation theory (CNT) in CAM5 and ACME, and with in situ observations. Significantly higher INP concentrations (by up to a factor of 5) are simulated from Niemand et al. than DeMott et al. and CNT especially over the dust source regions in both CAM5 and ACME. Interestingly the ACME model simulates higher INP concentrations than CAM5, especially in the Polar regions. This is also the case when we nudge the two models' winds and temperature towards the same reanalysis, indicating more efficient transport of aerosols (dust) to the Polar regions in ACME. Next, we examine the responses of model simulated cloud liquid water and ice water contents to different INP concentrations from three ice nucleation parameterizations (Niemand et al., DeMott et al., and CNT) in CAM5 and ACME. Changes in liquid water path (LWP) reach as much as 20% in the Arctic regions in ACME between the three parameterizations while the LWP changes are smaller and limited in the Northern Hemispheric mid-latitudes in CAM5. Finally, the impacts on cloud radiative forcing and dust indirect effects on mixed-phase clouds are quantified with the three ice nucleation parameterizations in CAM5 and ACME.

  19. Executive Summary - Historical background

    International Nuclear Information System (INIS)

    2005-01-01

    The Institute of Nuclear Physics (INP) was established in Cracow in 1955. The post-war excitement of engaging in scientific activity, can certainly be credited to the talent, experience and unusual personality of Professor Henryk Niewodniczanski, the founder and first Director of the INP. In the 60's the INP research activity was concentrated around the Russian U120 Cyclotron, built in 1958 which provided deuteron beams up to 14.5 MeV and of alpha particles up to 29 MeV. A small 48 cm pole-piece cyclotron with was in-house constructed, and used for PIXE analyses and RBA material studies. In 1960's, the nuclear spectroscopy group began building several types of magnetic beta ray spectrometers to study excited levels of neutron-deficient isotopes provided by the 660 MeV cyclotron of the JINR. In parallel, studies of spin polarization of n and p emitted in the deuteron stripping reaction were performed. Studies of condensed matter using pulsed neutron beams from the IBR30 and Kjeller (Norway) reactors had also began. The NMR signal was first observed in Poland by physicists from the Jagiellonian University, and a well equipped NMR Laboratory was also created at the INP. A small theoretical physics department was established to support experimental research. Applied physics, based on the research performed in the INP was also developed. Following the interest in fast neutron radiotherapy, initiated by the Gray Laboratory in Hammersmith, a beam of fast neutrons was produced on a Be target by 13.5 MeV deuterons from the U120 and applied for cancer therapy, in a collaborative effort with the Centre of Oncology in Cracow. Over a period of 10 years, some 500 patients were treated, in selected types of salivary gland cancer and post-mastectomy recurrences. In the late 60's a technology of thermoluminescent dosimeters (TLD) was developed at the INP, based on specially activated LiF. The method was patented and TLDs, manufactured at the INP, are nowadays applied by in over 30

  20. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. The concentration of carbon source in the medium affects the quality of virus-like particles of human papillomavirus type 16 produced in Saccharomyces cerevisiae.

    Science.gov (United States)

    Kim, Hyoung Jin; Jin, Yingji; Kim, Hong-Jin

    2014-01-01

    There is accumulating evidence that virus-like particles (VLPs) recombinantly produced in Saccharomyces cerevisiae (S. cerevisiae) are characterized by low structural stability, and that this is associated with reduced antigenicity and immunogenicity. However, little attention has been devoted to methods of improving the quality of the VLPs. Here, we investigated the effect of carbon source concentration in the medium on the antigenicity and immunogenicity of human papillomavirus (HPV) type 16 L1 VLPs expressed in S. cerevisiae from the galactose promoter. Media containing 2, 4, 6, and 8% carbon source, composed of both glucose and galactose in equal proportion, were used. VLP antigenicity was enhanced in cultures grown on media with 6 or 8% carbon source, compared to those from cultures with less than 6% carbon source. Moreover, the VLPs obtained from these cultures induced higher anti-HPV16 L1 IgG titers and neutralizing antibody titers in immunized mice than those purified from cultures with less than 6% carbon source. Our results indicate that the concentration of the carbon source in the medium plays a crucial role in determining the antigenicity and immunogenicity of HPV type16 L1 VLPs.

  2. Study of particle swarm optimization particle trajectories

    CSIR Research Space (South Africa)

    Van den Bergh, F

    2006-01-01

    Full Text Available Particle swarm optimization (PSO) has shown to be an efficient, robust and simple optimization algorithm. Most of the PSO studies are empirical, with only a few theoretical analyses that concentrate on understanding particle trajectories...

  3. 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.

    2015-01-01

    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.

  4. Concentrations and source regions of light-absorbing particles in snow/ice in northern Pakistan and their impact on snow albedo

    Science.gov (United States)

    Gul, Chaman; Praveen Puppala, Siva; Kang, Shichang; Adhikary, Bhupesh; Zhang, Yulan; Ali, Shaukat; Li, Yang; Li, Xiaofei

    2018-04-01

    Black carbon (BC), water-insoluble organic carbon (OC), and mineral dust are important particles in snow and ice which significantly reduce albedo and accelerate melting. Surface snow and ice samples were collected from the Karakoram-Himalayan region of northern Pakistan during 2015 and 2016 in summer (six glaciers), autumn (two glaciers), and winter (six mountain valleys). The average BC concentration overall was 2130 ± 1560 ng g-1 in summer samples, 2883 ± 3439 ng g-1 in autumn samples, and 992 ± 883 ng g-1 in winter samples. The average water-insoluble OC concentration overall was 1839 ± 1108 ng g-1 in summer samples, 1423 ± 208 ng g-1 in autumn samples, and 1342 ± 672 ng g-1 in winter samples. The overall concentration of BC, OC, and dust in aged snow samples collected during the summer campaign was higher than the concentration in ice samples. The values are relatively high compared to reports by others for the Himalayas and the Tibetan Plateau. This is probably the result of taking more representative samples at lower elevation where deposition is higher and the effects of ageing and enrichment are more marked. A reduction in snow albedo of 0.1-8.3 % for fresh snow and 0.9-32.5 % for aged snow was calculated for selected solar zenith angles during daytime using the Snow, Ice, and Aerosol Radiation (SNICAR) model. The daily mean albedo was reduced by 0.07-12.0 %. The calculated radiative forcing ranged from 0.16 to 43.45 W m-2 depending on snow type, solar zenith angle, and location. The potential source regions of the deposited pollutants were identified using spatial variance in wind vector maps, emission inventories coupled with backward air trajectories, and simple region-tagged chemical transport modeling. Central, south, and west Asia were the major sources of pollutants during the sampling months, with only a small contribution from east Asia. Analysis based on the Weather Research and Forecasting (WRF-STEM) chemical transport model identified a

  5. Variability of Black Carbon and Ultrafine Particle Concentration on Urban Bike Routes in a Mid-Sized City in the Po Valley (Northern Italy

    Directory of Open Access Journals (Sweden)

    Giovanni Lonati

    2017-02-01

    Full Text Available Cyclists might experience increased air pollution exposure, due to the proximity to traffic, and higher intake, due to their active travel mode and higher ventilation. Several local factors, like meteorology, road and traffic features, and bike lanes features, affect cyclists’ exposure to traffic-related pollutants. This paper investigates the concentration levels and the effect of the features of the bike lanes on cyclists’ exposure to airborne ultrafine particulate matter (UFP and black carbon (BC in the mid-sized city of Piacenza, located in the middle of the Po Valley, Northern Italy. Monitoring campaigns were performed by means of portable instruments along different urban bike routes with bike lanes, characterized by different distances from the traffic source (on-road cycle lane, separated cycle lane, green cycle path, during morning (9:00 am–10:00 am and evening (17:30 pm–18:30 pm workday rush hours in both cold and warm seasons. The proximity to traffic significantly affected cyclists’ exposure to UFP and BC: exposure concentrations measured for the separated lane and for the green path were 1–2 times and 2–4 times lower than for the on-road lane. Concurrent measurements showed that exposure concentrations to PM10, PM2.5, and PM1 were not influenced by traffic proximity, without any significant variation between on-road cycle lane, separated lane, or green cycle path. Thus, for the location of this study PM mass-based metrics were not able to capture local scale concentration gradients in the urban area as a consequence of the rather high urban and regional background that hides the contribution of local scale sources, such as road traffic. The impact of route choice on cyclists’ exposure to UFPs and BC during commuting trips back and forth from a residential area to the train station has been also estimated through a probabilistic approach through an iterative Monte Carlo technique, based on the measured data. Compared

  6. The plasma concentration of HDL-associated apoM is influenced by LDL receptor-mediated clearance of apoB-containing particles

    DEFF Research Database (Denmark)

    Christoffersen, Christina; Benn, Marianne; Christensen, Pernille Møller

    2012-01-01

    ApoM is mainly associated with HDL. Nevertheless, we have consistently observed positive correlations of apoM with plasma LDL cholesterol in humans. Moreover, LDL receptor deficiency is associated with increased plasma apoM in mice. Here, we tested the idea that plasma apoM concentrations...... are affected by the rate of LDL receptor-mediated clearance of apoB-containing particles. We measured apoM in humans each carrying one of three different LDL receptor mutations (n = 9) or the apoB3500 mutation (n = 12). These carriers had increased plasma apoM (1.34 ± 0.13 µM, P = 0.003, and 1.23 ± 0.10 µM, P...... = 0.02, respectively) as compared with noncarriers (0.93 ± 0.04 µM). When we injected human apoM-containing HDL into Wt (n = 6) or LDL receptor-deficient mice (n = 6), the removal of HDL-associated human apoM was delayed in the LDL receptor-deficient mice. After 2 h, 54 ± 5% versus 90 ± 8% (P

  7. Effects of salinity and particle concentration on sediment hydrodynamics and critical bed-shear-stress for erosion of fine grained sediments used in wetland restoration projects

    Directory of Open Access Journals (Sweden)

    M. Ghose-Hajra

    2015-03-01

    Full Text Available Sea-level rise, the increasing number and intensity of storms, oil and groundwater extraction, and coastal land subsidence are putting people and property at risk along Louisiana’s coast, with major implications for human safety and economic health of coastal areas. A major goal towards re-establishing a healthy and sustainable coastal ecosystem has been to rebuild Louisiana’s disappearing wetlands with fine grained sediments that are dredged or diverted from nearby rivers, channels and lakes to build land in open water areas. A thorough geo-hydrodynamic characterization of the deposited sediments is important in the correct design and a more realistic outcome assessment of the long-term performance measures for ongoing coastal restoration projects. This paper evaluates the effects of salinity and solid particle concentration on the re-suspension characteristics of fine-grained dredged sediments obtained from multiple geographic locations along the Gulf coast. The critical bed-shear-stress for erosion has been evaluated as a function of sedimentation time. The sediment hydrodynamic properties obtained from the laboratory testing were used in a numerical coastal sediment distribution model to aid in evaluating sediment diversions from the Mississippi River into Breton Sound and Barataria Bay.

  8. Exposure to particles from laser printers operating within office workplaces.

    Science.gov (United States)

    McGarry, Peter; Morawska, Lidia; He, Congrong; Jayaratne, Rohan; Falk, Matthew; Tran, Quang; Wang, Hao

    2011-08-01

    While recent research has provided valuable information as to the composition of laser printer particles, their formation mechanisms, and explained why some printers are emitters while others are low emitters, questions relating to the potential exposure of office workers remained unanswered. In particular, (i) what impact does the operation of laser printers have on the background particle number concentration (PNC) of an office environment over the duration of a typical working day? (ii) What is the airborne particle exposure to office workers in the vicinity of laser printers? (iii) What influence does the office ventilation have upon the transport and concentration of particles? (iv) Is there a need to control the generation of, and/or transport of particles arising from the operation of laser printers within an office environment? (v) What instrumentation and methodology is relevant for characterizing such particles within an office location? We present experimental evidence on printer temporal and spatial PNC during the operation of 107 laser printers within open plan offices of five buildings. The 8 h time-weighted average printer particle exposure is significantly less than the 8 h time-weighted local background particle exposure, but that peak printer particle exposure can be greater than 2 orders of magnitude higher than local background particle exposure. The particle size range is predominantly ultrafine (printer derived particles. We also propose, for the first time, that peak particle reference values be calculated for each office area analogous to the criteria used in Australia and elsewhere for evaluating exposure excursion above occupational hazardous chemical exposure standards. A universal peak particle reference value of 2.0 × 10(4) particles cm(-3) has been proposed.

  9. Compensatable muon collider calorimeter with manageable backgrounds

    Science.gov (United States)

    Raja, Rajendran

    2015-02-17

    A method and system for reducing background noise in a particle collider, comprises identifying an interaction point among a plurality of particles within a particle collider associated with a detector element, defining a trigger start time for each of the pixels as the time taken for light to travel from the interaction point to the pixel and a trigger stop time as a selected time after the trigger start time, and collecting only detections that occur between the start trigger time and the stop trigger time in order to thereafter compensate the result from the particle collider to reduce unwanted background detection.

  10. Use of mineral magnetic concentration data as a particle size proxy: a case study using marine, estuarine and fluvial sediments in the Carmarthen Bay area, South Wales, U.K.

    Science.gov (United States)

    Booth, C A; Walden, J; Neal, A; Smith, J P

    2005-07-15

    Compositional (non-magnetic) data can correlate strongly with particle size, which deems it appropriate as a particle size proxy and, therefore, a reliable means of normalising analytical data for particle size effects. Previous studies suggest magnetic concentration parameters represent an alternative means of normalising for these effects and, given the speed, low-cost and sensitivity of the measurements may, therefore, offer some advantages over other compositional signals. In this work, contemporary sediments from a range of depositional environments have been analysed with regard to their mineral magnetic concentration and textural characteristics, to observe if the strength and nature of the relationship identified in previous studies is universal. Our data shows magnetic parameters (chi(LF), chi(ARM) and SIRM) possess contrasting relationships with standard textural parameters for sediment samples collected from marine (Carmarthen Bay), estuarine (Gwendraeth Estuary) and fluvial (Rivers Gwendraeth Fach and Gwendraeth Fawr) settings. Magnetic concentrations of sediments from both the marine and estuarine environments are highly influenced by the magnetic contribution of finer particle sizes; Gwendraeth Fawr River sediments are influenced by the magnetic contribution of coarser particle sizes, while sediments from the Gwendraeth Fach River are not influenced significantly by any variations in textural properties. These results indicate mineral magnetic measurements have considerable potential as a particle size proxy for particular sedimentary environments, which in certain instances could be useful for geochemical, sediment transport, and sediment provenance studies. However, the data also highlight the importance of fully determining the nature of the relationship between sediment particle size and magnetic properties before applying mineral magnetic data as a particle size proxy.

  11. Detection and Quantification of Silver Nanoparticles at Environmentally Relevant Concentrations Using Asymmetric Flow Field??Flow Fractionation Online with Single Particle Inductively Coupled Plasma Mass Spectrometry

    Science.gov (United States)

    The presence of silver nanoparticles (AgNPs) in aquatic environments could potentially cause adverse impacts on ecosystems and human health. However, current understanding of the environmental fate and transport of AgNPs is still limited because their properties in complex environmental samples cannot be accurately determined. In this study, the feasibility of using asymmetric flow field-flow fractionation (AF4) connected online with single particle inductively coupled plasma mass spectrometry (spICPMS) to detect and quantify AgNPs at environmentally relevant concentrations was investigated. The AF4 channel had a thickness of 350 00b5m and its accumulation wall was a 10 kDa regenerated cellulose membrane. A 0.02 % FL-70 surfactant solution was used as an AF4 carrier. With 1.2 mL/min AF4 cross flow rate, 1.5 mL/min AF4 channel flow rate, and 5 ms spICPMS dwell time, the AF4??spICPMS can detect and quantify 40 ?? 80 nm AgNPs, as well as Ag-SiO2 nanoparticles (51.0 nm diameter Ag core and 21.6 nm SiO2 shell), with good recovery within 30 min. This system was not only effective in differentiating and quantifying different types of AgNPs with similar hydrodynamic diameters, such as in mixtures containing Ag-SiO2 core-shell nanoparticles and 40 ?? 80 nm AgNPs, but also suitable for differentiating between 40 nm AgNPs and elevated dissolved Ag content. The study results indicate that AF4??spICPMS is capable of detecting and quantifying AgNPs and other engineered

  12. Particle Astrophysics of Neutrinos

    Indian Academy of Sciences (India)

    Amol Dighe

    Cosmic microwave background photons: 400 / cm3. Cosmic background neutrinos: 330 / cm3. The lightest massive particles. A million times lighter than the electron. No direct mass measurement yet. The most weakly interacting particles. Do not interact with light ⇒ Dark matter. Stopping radiation with lead shielding:.

  13. Particle growth kinetics over the Amazon rainforest

    Science.gov (United States)

    Pinterich, T.; Andreae, M. O.; Artaxo, P.; Kuang, C.; Longo, K.; Machado, L.; Manzi, A. O.; Martin, S. T.; Mei, F.; Pöhlker, C.; Pöhlker, M. L.; Poeschl, U.; Shilling, J. E.; Shiraiwa, M.; Tomlinson, J. M.; Zaveri, R. A.; Wang, J.

    2016-12-01

    Aerosol particles larger than 100 nm play a key role in global climate by acting as cloud condensation nuclei (CCN). Most of these particles, originated from new particle formation or directly emitted into the atmospheric, are initially too small to serve as CCN. These small particles grow to CCN size mainly through condensation of secondary species. In one extreme, the growth is dictated by kinetic condensation of very low-volatility compounds, favoring the growth of the smallest particles; in the other extreme, the process is driven by Raoult's law-based equilibrium partitioning of semi-volatile organic compound, favoring the growth of larger particles. These two mechanisms can lead to very different production rates of CCN. The growth of particles depends on a number of parameters, including the volatility of condensing species, particle phase, and diffusivity inside the particles, and this process is not well understood in part due to lack of ambient data. Here we examine atmospheric particle growth using high-resolution size distributions measured onboard the DOE G-1 aircraft during GoAmazon campaign, which took place from January 2014 to December 2015 near Manaus, Brazil, a city surrounded by natural forest for over 1000 km in every direction. City plumes are clearly identified by the strong enhancement of nucleation and Aitken mode particle concentrations over the clean background. As the plume traveled downwind, particle growth was observed, and is attributed to condensation of secondary species and coagulation (Fig.1). Observed aerosol growth is modeled using MOSAIC (Model for Simulating Aerosol Interactions and Chemistry), which dynamically partitions multiple compounds to all particle size bins by taking into account compound volatility, gas-phase diffusion, interfacial mass accommodation, particle-phase diffusion, and particle-phase reaction. The results from both wet and dry seasons will be discussed.

  14. Factors affecting color strength of printing on film-coated tablets by UV laser irradiation: TiO2 particle size, crystal structure, or concentration in the film, and the irradiated UV laser power.

    Science.gov (United States)

    Hosokawa, Akihiro; Kato, Yoshiteru

    2011-08-01

    The purpose of this article is to study factors affecting color strength of printing on film-coated tablets by ultraviolet (UV) laser irradiation: particle size, crystal structure, or concentration of titanium dioxide (TiO2) in film, and irradiated UV laser power. Hydroxypropylmethylcellulose films containing 4.0% of TiO2, of which BET particle sizes were ranging from 126.1 to 219.8 nm, were irradiated 3.14W of UV laser at a wavelength 355 nm to study effects of TiO2 particle size and crystal structure on the printing. The films containing TiO2 concentration ranging from 1.0 to 7.7% were irradiated 3.14 or 5.39W of the UV laser to study effect of TiO2 concentration on the printing. The film containing 4.0% of TiO2, was irradiated the UV laser up to 6.42W to study effect of the UV laser power on the printing. The color strength of the printed films was estimated by a spectrophotometer as total color difference (dE). Particle size, crystal structure, and concentration of TiO2 in the films did not affect the printing. In the relationship between the irradiated UV laser power and dE, there found an inflection point (1.6W). When the UV laser power was below 1.6W, the films were not printed. When it was beyond the point, total color difference increased linearly in proportion with the irradiated laser power. The color strength of the printing on film was not changed by TiO2 particle size, crystal structure, and concentration, but could be controlled by regulating the irradiated UV laser power beyond the inflection point.

  15. Hanford Site background: Part 1, Soil background for nonradioactive analytes

    International Nuclear Information System (INIS)

    1993-04-01

    The determination of soil background is one of the most important activities supporting environmental restoration and waste management on the Hanford Site. Background compositions serve as the basis for identifying soil contamination, and also as a baseline in risk assessment processes used to determine soil cleanup and treatment levels. These uses of soil background require an understanding of the extent to which analytes of concern occur naturally in the soils. This report documents the results of sampling and analysis activities designed to characterize the composition of soil background at the Hanford Site, and to evaluate the feasibility for use as Sitewide background. The compositions of naturally occurring soils in the vadose Zone have been-determined for-nonradioactive inorganic and organic analytes and related physical properties. These results confirm that a Sitewide approach to the characterization of soil background is technically sound and is a viable alternative to the determination and use of numerous local or area backgrounds that yield inconsistent definitions of contamination. Sitewide soil background consists of several types of data and is appropriate for use in identifying contamination in all soils in the vadose zone on the Hanford Site. The natural concentrations of nearly every inorganic analyte extend to levels that exceed calculated health-based cleanup limits. The levels of most inorganic analytes, however, are well below these health-based limits. The highest measured background concentrations occur in three volumetrically minor soil types, the most important of which are topsoils adjacent to the Columbia River that are rich in organic carbon. No organic analyte levels above detection were found in any of the soil samples

  16. Low Background Micromegas in CAST

    DEFF Research Database (Denmark)

    Garza, J G; Aune, S.; Aznar, F.

    2014-01-01

    Solar axions could be converted into x-rays inside the strong magnetic field of an axion helioscope, triggering the detection of this elusive particle. Low background x-ray detectors are an essential component for the sensitivity of these searches. We report on the latest developments of the Micr......Solar axions could be converted into x-rays inside the strong magnetic field of an axion helioscope, triggering the detection of this elusive particle. Low background x-ray detectors are an essential component for the sensitivity of these searches. We report on the latest developments...... of the Micromegas detectors for the CERN Axion Solar Telescope (CAST), including technological pathfinder activities for the future International Axion Observatory (IAXO). The use of low background techniques and the application of discrimination algorithms based on the high granularity of the readout have led...... to background levels below 10−6 counts/keV/cm2/s, more than a factor 100 lower than the first generation of Micromegas detectors. The best levels achieved at the Canfranc Underground Laboratory (LSC) are as low as 10−7 counts/keV/cm2/s, showing good prospects for the application of this technology in IAXO...

  17. Concerning background from calorimeter ports

    International Nuclear Information System (INIS)

    Digiacomo, N.J.

    1985-01-01

    Any detector system viewing a port or slit in a calorimeter wall will see, in addition to the primary particles of interest, a background of charged and neutral particles and photons generated by scattering from the port walls and by leakage from incompletely contained primary particle showers in the calorimeter near the port. The signal to noise ratio attainable outside the port is a complex function of the primary source spectrum, the calorimeter and port design and, of course, the nature and acceptance of the detector system that views the port. Rather than making general statements about the overall suitability (or lack thereof) of calorimeter ports, we offer here a specific example based on the external spectrometer and slit of the NA34 experiment. This combination of slit and spectrometer is designed for fixed-target work, so that the primary particle momentum spectrum contains higher momentum particles than expected in a heavy ion colliding beam environment. The results are, nevertheless, quite relevant for the collider case

  18. A definition of background independence

    International Nuclear Information System (INIS)

    Gryb, Sean

    2010-01-01

    We propose a definition for background (in)/dependence in dynamical theories of the evolution of configurations that have a continuous symmetry and test this definition on particle models and on gravity. Our definition draws from Barbour's best matching framework developed for the purpose of implementing spatial and temporal relationalism. Among other interesting theories, general relativity can be derived within this framework in novel ways. We study the detailed canonical structure of a wide range of best matching theories and show that their actions must have a local gauge symmetry. When gauge theory is derived in this way, we obtain at the same time a conceptual framework for distinguishing between background-dependent and -independent theories. Gauge invariant observables satisfying Kuchar's criterion are identified and, in simple cases, explicitly computed. We propose a procedure for inserting a global background time into temporally relational theories. Interestingly, using this procedure in general relativity leads to unimodular gravity.

  19. Analysis of lung tissue particles among silicosis cases

    Directory of Open Access Journals (Sweden)

    B Case

    2005-10-01

    Full Text Available Background and Aims:Lung tissue samples of several miners, millers, sandblaster, welders andconstruction workers with historical exposure to mineral particles were analyzed. These subjectshad significant respiratory exposure to silica particles and demanded compensation foroccupational lung diseases.Method: Lung tissue samples were observed under an Electron microscope with 10000Xmagnification. Mineral particles were sized and analyzed by EDS detector based on X-rayspectrophotometry.Results: The results have indicated that the lung particle burden of the subjects was closelyrelated to their occupational history. The highest level of mineral silica particles were found in thelungs of miners and sandblasters. The highest concentration of metallic particles was found in thelungs of welders and miners in ferric mining industry. Severity of lung fibrosis was directlyrelated to the lung free silica concentration. However, no association was found between particlediameter and severity of fibrosis. In addition, lung particle burden of silicotic cases with lungcancer contained a much higher concentration of metallic particles and asbestos fibres that thelung of those subject with silicosis only.Conclusion: Although workers in mining and construction may be predominantly exposed tosilica particles including quartz, the role of other mineral particles including asbestos fibres,metallic fibres and other minerals should be taken into account in the genesis of occupational lungdisease in particular lung cancer. Lung tissue sample analysis can provide valuable informationto assess the legal and compensation cases.

  20. High sensitivity fluorescent single particle and single molecule detection apparatus and method

    Science.gov (United States)

    Mathies, Richard A.; Peck, Konan; Stryer, Lubert

    1990-01-01

    Apparatus is described for ultrasensitive detection of single fluorescent particles down to the single fluorescent molecule limit in a fluid or on a substrate comprising means for illuminating a predetermined volume of the fluid or area of the substrate whereby to emit light including background light from the fluid and burst of photons from particles residing in the area. The photon burst is detected in real time to generate output representative signal. The signal is received and the burst of energy from the fluorescent particles is distinguished from the background energy to provide an indication of the number, location or concentration of the particles or molecules.

  1. Particle detectors

    CERN Document Server

    AUTHOR|(CDS)2068232

    1998-01-01

    The lecture series will present and overview of the basic techniques and underlying physical principles of particle detectors, applied to current and future high energy physics experiments. Illustrating examples, mainly from the field of collider experiments, will demonstrate the performance and limitations of the various techniques. After and introduction we shall concentrate on particle tracking. Wire chambers, drift chambers, micro gaseous tracking devices and solid state trackers will be discussed. It follows and overview of scintillators, photon detection, fiber tracking and nuclear emulsions. One lecture will deal with the various techniques of calorimetry. Finally we shall focus on methods developed for particle identification. These comprise specific energy loss, time of flight Cherenkov and transition radiation detectors.

  2. Dust Particle Size Distributions during Spring in Yinchuan, China

    OpenAIRE

    Jiangfeng Shao; Jiandong Mao

    2016-01-01

    Dust particle size distributions in Yinchuan, China, were measured during March and April 2014, using APS-3321 sampler. The distributions were measured under different dust conditions (background, floating dust, blowing dust, and dust storm) and statistical analyses were performed. The results showed that, under different dust conditions, the instantaneous number concentrations of dust particles differed widely. For example, during blowing sand and dust storm conditions, instantaneous dust pa...

  3. Concentration and Preservation of Very Low Abundance Biomarkers in Urine, such as Human Growth Hormone (hGH), by Cibacron Blue F3G-A Loaded Hydrogel Particles.

    Science.gov (United States)

    Fredolini, Claudia; Meani, Francesco; Reeder, K Alex; Rucker, Sally; Patanarut, Alexis; Botterell, Palma J; Bishop, Barney; Longo, Caterina; Espina, Virginia; Petricoin, Emanuel F; Liotta, Lance A; Luchini, Alessandra

    2008-12-01

    Urine is a potential source of diagnostic biomarkers for detection of diseases, and is a very attractive means of non-invasive biospecimen collection. Nonetheless, proteomic measurement in urine is very challenging because diagnostic biomarkers exist in very low concentration (usually below the sensitivity of common immunoassays) and may be subject to rapid degradation. Hydrogel nanoparticles functionalized with Cibacron Blue F3G-A (CB) have been applied to address these challenges for urine biomarker measurement. We chose one of the most difficult low abundance, but medically relevant, hormones in the urine: human growth hormone (hGH). The normal range of hGH in serum is 1 to 10 ng/mL but the urine concentration is suspected to be a thousand times less, well below the detection limit (50 pg/mL) of sensitive clinical hGH immunoassays. We demonstrate that CB particles can capture, preserve and concentrate hGH in urine at physiological salt and urea concentrations, so that hGH can be measured in the linear range of a clinical immunometric assay. Recombinant and cadaveric hGH were captured from synthetic and human urine, concentrated and measured with an Immulite chemiluminescent immunoassay. Values of hGH less than 0.05 ng/mL (the Immulite detection limit) were concentrated to 2 ng/mL, with a urine volume of 1 mL. Dose response studies using 10 mL of urine demonstrated that the concentration of hGH in the particle eluate was linearly dependent on the concentration of hGH in the starting solution, and that all hGH was removed from solution. Thus if the starting urine volume is 100 mL, the detection limit will be 0.1 pg/mL. Urine from a healthy donor whose serum hGH concentration was 1.34 ng/mL was studied in order detect endogenous hGH. Starting from a volume of 33 mL, the particle eluate had an hGH concentration of 58 pg/mL, giving an estimated initial concentration of hGH in urine of 0.175 pg/mL. The nanotechnology described here appears to have the desired

  4. String pair production in non homogeneous backgrounds

    International Nuclear Information System (INIS)

    Bolognesi, S.; Rabinovici, E.; Tallarita, G.

    2016-01-01

    We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is less suppressed than the rate of particle pair production. We discuss in some detail how the critical field is affected by the non-homogeneity, for both time and space dependent electric field backgrouds. We also comment on what could be an interesting new prediction for the small field limit. The third case we consider is pair production in holographic confining backgrounds with homogeneous and non-homogeneous fields.

  5. String pair production in non homogeneous backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Bolognesi, S. [Department of Physics “E. Fermi” University of Pisa, and INFN - Sezione di Pisa,Largo Pontecorvo, 3, Ed. C, 56127 Pisa (Italy); Rabinovici, E. [Racah Institute of Physics, The Hebrew University of Jerusalem,91904 Jerusalem (Israel); Tallarita, G. [Departamento de Ciencias, Facultad de Artes Liberales,Universidad Adolfo Ibáñez, Santiago 7941169 (Chile)

    2016-04-28

    We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is less suppressed than the rate of particle pair production. We discuss in some detail how the critical field is affected by the non-homogeneity, for both time and space dependent electric field backgrouds. We also comment on what could be an interesting new prediction for the small field limit. The third case we consider is pair production in holographic confining backgrounds with homogeneous and non-homogeneous fields.

  6. The atherogenic plasma remnant-like particle cholesterol concentration is increased in the fasting and postprandial state in active acromegalic patients

    NARCIS (Netherlands)

    Twickler, T. B.; Dallinga-Thie, G. M.; Zelissen, P. M.; Koppeschaar, H. P.; Erkelens, D. W.

    2001-01-01

    BACKGROUND: Premature atherosclerosis is a clinical feature in untreated acromegaly. Increased postprandial lipoprotein remnant levels are associated with premature atherosclerosis. In most studies, remnants have been measured indirectly using retinyl esters (RE) as a chylomicron core label.

  7. Measured In Situ Atmospheric Ambient Aerosol Size-Distributions, Particle Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal, AL, April-May 2015

    Science.gov (United States)

    2015-09-01

    afternoon were a result of vehicular travel along the road that boarders the TSI aerosol probe. ............................................11 v...result of vehicular travel along the road that boarders the TSI aerosol probe...were conducted using a TSI aerodynamic particle sizing (APS) spectrometer, Model 3321 that provides high-resolution, real-time aerodynamic

  8. Particle Pollution

    Science.gov (United States)

    ... Your Health Particle Pollution Public Health Issues Particle Pollution Recommend on Facebook Tweet Share Compartir Particle pollution — ... see them in the air. Where does particle pollution come from? Particle pollution can come from two ...

  9. Physical properties of the arctic summer aerosol particles in relation ...

    Indian Academy of Sciences (India)

    The sea-salt particles of marine origin generated within the Arctic circle are identified as the main source of the Arctic summer aerosols. ... concentration starts decreasing within a few minutes from the start of these events but requires a few hours to restore to the normal background aerosol level after the end of event.

  10. Factors Governing the Precision of Subvisible Particle Measurement Methods - A Case Study with a Low-Concentration Therapeutic Protein Product in a Prefilled Syringe.

    Science.gov (United States)

    Ríos Quiroz, Anacelia; Lamerz, Jens; Da Cunha, Thierry; Boillon, Adeline; Adler, Michael; Finkler, Christof; Huwyler, Joerg; Schmidt, Roland; Mahler, Hanns-Christian; Koulov, Atanas V

    2016-02-01

    The current study was performed to assess the precision of the principal subvisible particle measurement methods available today. Special attention was given to identifying the sources of error and the factors governing analytical performance. The performance of individual techniques was evaluated using a commercial biologic drug product in a prefilled syringe container. In control experiments, latex spheres were used as standards and instrument calibration suspensions. The results reported in this manuscript clearly demonstrated that the particle measurement techniques operating in the submicrometer range have much lower precision than the micrometer size-range methods. It was established that the main factor governing the relatively poor precision of submicrometer methods in general and inherently, is their low sampling volume and the corresponding large extrapolation factors for calculating final results. The variety of new methods for submicrometer particle analysis may in the future support product characterization; however, the performance of the existing methods does not yet allow for their use in routine practice and quality control.

  11. Particle exposure and inhaled dose during commuting in Singapore

    Science.gov (United States)

    Tan, Sok Huang; Roth, Matthias; Velasco, Erik

    2017-12-01

    Exposure concentration and inhaled dose of particles during door-to-door trips walking and using motorized transport modes (subway, bus, taxi) are evaluated along a selected route in a commercial district of Singapore. Concentrations of particles smaller than 2.5 μm in size (PM2.5), black carbon, particle-bound polycyclic aromatic hydrocarbons, number of particles, active surface area and carbon monoxide have been measured in-situ using portable instruments. Simultaneous measurements were conducted at a nearby park to capture the background concentrations. The heart rate of the participants was monitored during the measurements as a proxy of the inhalation rate used to calculate the inhaled dose of particles. All measured metrics were highest and well above background levels during walking. No significant difference was observed in the exposure concentration of PM2.5 for the three motorized transport modes, unlike for the metrics associated with ultrafine particles (UFP). The concentration of these freshly emitted particles was significantly lower on subway trips. The absence of combustion sources, use of air conditioning and screen doors at station platforms are effective measures to protect passengers' health. For other transport modes, sections of trips close to accelerating and idling vehicles, such as bus stops, traffic junctions and taxi stands, represent hotspots of particles. Reducing the waiting time at such locations will lower pollutants exposure and inhaled dose during a commute. After taking into account the effect of inhalation and travel duration when calculating dose, the health benefit of commuting by subway for this particular district of Singapore became even more evident. For example, pedestrians breathe in 2.6 and 3.2 times more PM2.5 and UFP, respectively than subway commuters. Public buses were the second best alternative. Walking emerged as the worst commuting mode in terms of particle exposure and inhaled dose.

  12. Simulation of Experimental Background using FLUKA

    Energy Technology Data Exchange (ETDEWEB)

    Rokni, Sayed

    1999-05-11

    In November 1997, Experiment T423 began acquiring data with the intentions of understanding the energy spectra of high-energy neutrons generated in the interaction of electrons with lead. The following describes a series of FLUKA simulations studying (1) particle yields in the absence of all background; (2) the background caused from scattering in the room; (3) the effects of the thick lead shielding which surrounded the detector; (4) the sources of neutron background created in this lead shielding; and (5) the ratio of the total background to the ideal yield. In each case, particular attention is paid to the neutron yield.

  13. Measured gas and particle temperatures in VTT's entrained flow reactor

    DEFF Research Database (Denmark)

    Clausen, Sønnik; Sørensen, L.H.

    2006-01-01

    Particle and gas temperature measurements were carried out in experiments on VTTs entrained flow reactor with 5% and 10% oxygen using Fourier transform infrared emission spectroscopy (FTIR). Particle temperature measurements were performed on polish coal,bark, wood, straw particles, and bark...... and wood particles treated with additive. A two-color technique with subtraction of the background light was used to estimate particle temperatures during experiments. A transmission-emission technique was used tomeasure the gas temperature in the reactor tube. Gas temperature measurements were in good...... agreement with thermocouple readings. Gas lines and bands from CO, CO2 and H2O can be observed in the spectra. CO was only observed at the first measuring port (100ms) with the strongest CO-signal seen during experiments with straw particles. Variations in gas concentration (CO2 and H2O) and the signal from...

  14. The apolipoprotein A5 -1131T>C promoter polymorphism in Koreans: association with plasma APOA5 and serum triglyceride concentrations, LDL particle size and coronary artery disease

    Science.gov (United States)

    BACKGROUND: The association between -1131T>C single nucleotide polymorphism (SNP) of the apolipoprotein A5 gene (APOA5) and hypertriglyceridemia raised the possibility that this SNP could be related to coronary artery disease (CAD) risk. Therefore, we investigated the association of this APOA5 -1131...

  15. Particle interactions during sedimentation

    Science.gov (United States)

    Michaelides, Efstathios; Xu, Zu-Jia

    2002-11-01

    The confined sedimentation process of two-dimensional particles with several initial configurations is numerically investigated at very low to moderate particle Reynolds numbers. The Lattice Boltzmann Method is used to simulate the hydrodynamic interactions between fluid and particles. We have found that, during the sedimentation process the displacement dispersion of particles in the horizontal direction fluctuates around zero, while the dispersion in the vertical direction increases monotonically and almost linearly. We also found that the increasing dispersion rate heavily depends on the initial layout and any symmetry of the suspension. The simulations for non-cohesive particles show that the process of sedimentation encompasses three stages: In the first stage, the initial particle configuration plays a major role on the average velocity of the particles. A V-shape or W-shape front may be formed by the particles close to that front. During the second stage, the concentration is lower, strong particle interactions dominate and the formation and destruction of particle clusters play a major role in the process. The sedimentation velocity depends to a large extend on the number of clusters formed and the velocity field developed. During the third stage, the suspension stretches, concentration becomes lower and particle clusters appear to be more stable. The wakes generated by individual particles and clusters, especially the wake of the leading cluster becomes very important in the process. Simulations were also performed with cohesive particles and we found out that the sedimentation process is essentially governed by the formation and size of flocs.

  16. Transport of soil particles to the ocean and their concentration in the marine atmosphere - A case study of marine aerosols collected during the cruises of the Antarctic observation ship Shirase

    International Nuclear Information System (INIS)

    Tanaka, Shigeru; Okamori, Katsutaka; Hashimoto, Yoshikazu

    1991-01-01

    The marine aerosol samples over the West Pacific Ocean, the Indian Ocean, and the Antarctic Ocean, collected during the cruises of the Antarctic observation ship Shirase, were analyzed by X-ray fluorescence. As the results, the average concentration of soil derived elements were 11.9 ng/m 3 for Al, 50.6 ng/m 3 for Si, 12.5 ng/m 3 for Fe, over the West Pacific Ocean. These values were so low as 1/100 of their concentrations in the land. Furthermore, these concentrations over the Indian Ocean and the Antarctic Ocean were extremely low, 6.5 ng/m 3 for Al, 13.4 ng/m 3 for Si, 3.5 ng/m 3 for Fe with average. It is considered that these values are the background concentration of soil derived elements in the marine atmosphere

  17. Particle-in-cell vs straight-line airflow Gaussian calculations of concentration and deposition of airborne emissions out to 70 km for two sites of differing meteorological and topographical character

    International Nuclear Information System (INIS)

    Lange, R.; Dickerson, M.A.; Peterson, K.R.; Sherman, C.A.; Sullivan, T.J.

    1976-01-01

    Two numerical models for the calculation of air concentration and ground deposition of airborne effluent releases are compared. The Particle-in-Cell (PIC) model and the Straight-Line Airflow Gaussian model were used for the simulation. Two sites were selected for comparison: the Hudson River Valley, New York, and the area around the Savannah River Plant, South Carolina. Input for the models was synthesized from meteorological data gathered in previous studies by various investigators. It was found that the PIC model more closely simulated the three-dimensional effects of the meteorology and topography. Overall, the Gaussian model calculated higher concentrations under stable conditions with better agreement between the two methods during neutral to unstable conditions. In addition, because of its consideration of exposure from the returning plume after flow reversal, the PIC model calculated air concentrations over larger areas than did the Gaussian model

  18. The effect of long-range air mass transport pathways on PM10 and NO2 concentrations at urban and rural background sites in Ireland: Quantification using clustering techniques.

    Science.gov (United States)

    Donnelly, Aoife A; Broderick, Brian M; Misstear, Bruce D

    2015-01-01

    The specific aims of this paper are to: (i) quantify the effects of various long range transport pathways nitrogen dioxide (NO2) and particulate matter with diameter less than 10μm (PM10) concentrations in Ireland and identify air mass movement corridors which may lead to incidences poor air quality for application in forecasting; (ii) compare the effects of such pathways at various sites; (iii) assess pathways associated with a period of decreased air quality in Ireland. The origin of and the regions traversed by an air mass 96h prior to reaching a receptor is modelled and k-means clustering is applied to create air-mass groups. Significant differences in air pollution levels were found between air mass cluster types at urban and rural sites. It was found that easterly or recirculated air masses lead to higher NO2 and PM10 levels with average NO2 levels varying between 124% and 239% of the seasonal mean and average PM10 levels varying between 103% and 199% of the seasonal mean at urban and rural sites. Easterly air masses are more frequent during winter months leading to higher overall concentrations. The span in relative concentrations between air mass clusters is highest at the rural site indicating that regional factors are controlling concentration levels. The methods used in this paper could be applied to assist in modelling and forecasting air quality based on long range transport pathways and forecast meteorology without the requirement for detailed emissions data over a large regional domain or the use of computationally demanding modelling techniques.

  19. Macromodel for assessing residential concentrations of combustion-generated pollutants: Model development and preliminary predictions for CO, NO/sub 2/, and respirable suspended particles

    Energy Technology Data Exchange (ETDEWEB)

    Traynor, G.W.; Aceti, J.C.; Apte, M.G.; Smith, B.V.; Green, L.L.; Smith-Reiser, A.; Novak, K.M.; Moses, D.O.

    1989-01-01

    A simulation model (also called a ''macromodel'') has been developed to predict residential air pollutant concentration distributions for specified populations. The model inputs include the market penetration of pollution sources, pollution source characteristics (e.g., emission rates, source usage rates), building characteristics (e.g., house volume, air exchange rates), and meteorological parameters (e.g., outside temperature). Four geographically distinct regions of the US have been modeled using Monte Carlo and deterministic simulation techniques. Single-source simulations were also conducted. The highest predicted CO and NO/sub 2/ residential concentrations were associated with the winter-time use of unvented gas and kerosene space heaters. The highest predicted respirable suspended particulate concentrations were associated with indoor cigarette smoking and the winter-time use of non-airtight wood stoves, radiant kerosene heaters, convective unvented gas space heaters, and oil forced-air furnaces. Future field studies in this area should (1) fill information gaps identified in this report, and (2) collect information on the macromodel input parameters to properly interpret the results. It is almost more important to measure the parameters that affect indoor concentration than it is to measure the concentrations themselves.

  20. Dynamic Hydrogen Production from Methanol/Water Photo-Splitting Using Core@Shell-Structured CuS@TiO2 Catalyst Wrapped by High Concentrated TiO2 Particles

    Directory of Open Access Journals (Sweden)

    Younghwan Im

    2013-01-01

    Full Text Available This study focused on the dynamic hydrogen production ability of a core@shell-structured CuS@TiO2 photocatalyst coated with a high concentration of TiO2 particles. The rectangular-shaped CuS particles, 100 nm in length and 60 nm in width, were surrounded by a high concentration of anatase TiO2 particles (>4~5 mol. The synthesized core@shell-structured CuS@TiO2 particles absorbed a long wavelength (a short band gap above 700 nm compared to that pure TiO2, which at approximately 300 nm, leading to easier electronic transitions, even at low energy. Hydrogen evolution from methanol/water photo-splitting over the core@shell-structured CuS@TiO2 photocatalyst increased approximately 10-fold compared to that over pure CuS. In particular, 1.9 mmol of hydrogen gas was produced after 10 hours when 0.5 g of 1CuS@4TiO2 was used at pH = 7. This level of production was increased to more than 4-fold at higher pH. Cyclic voltammetry and UV-visible absorption spectroscopy confirmed that the CuS in CuS@TiO2 strongly withdraws the excited electrons from the valence band in TiO2 because of the higher reduction potential than TiO2, resulting in a slower recombination rate between the electrons and holes and higher photoactivity.

  1. Dust Particle Size Distributions during Spring in Yinchuan, China

    Directory of Open Access Journals (Sweden)

    Jiangfeng Shao

    2016-01-01

    Full Text Available Dust particle size distributions in Yinchuan, China, were measured during March and April 2014, using APS-3321 sampler. The distributions were measured under different dust conditions (background, floating dust, blowing dust, and dust storm and statistical analyses were performed. The results showed that, under different dust conditions, the instantaneous number concentrations of dust particles differed widely. For example, during blowing sand and dust storm conditions, instantaneous dust particles concentrations varied substantially, while, under floating dust conditions, concentration differences were relatively small. The average dust particles size distributions were unimodal under all dust conditions, but the average surface area and mass size distributions were all bimodal. These distributions had peaks in different locations under different dust conditions. Under different dust conditions, wind speed and humidity were very important factors for particles size distributions. With increasing wind speed and decreasing humidity, fine particles were dominant in the atmosphere and the number and mass distributions of the coarse particles were indicative of long-range transport from surrounding deserts. Different dust conditions had different influences on PM1, PM2.5, and PM10 concentrations.

  2. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    DEFF Research Database (Denmark)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard

    2018-01-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component...... of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper....... First, a ma terial equivalent to the ductile cast iron matrix is manufactured and subjected to dilato- metric and high-temperature tensile tests. Subsequently, a two-scale hierarchical top-down model is devised, calibrated on the basis of the collected data and used to simulate the interaction between...

  3. Reversible flow of cholesteryl ester between high-density lipoproteins and triacylglycerol-rich particles is modulated by the fatty acid composition and concentration of triacylglycerols

    Directory of Open Access Journals (Sweden)

    E.C.R. Quintão

    2010-12-01

    Full Text Available We determined the influence of fasting (FAST and feeding (FED on cholesteryl ester (CE flow between high-density lipoproteins (HDL and plasma apoB-lipoprotein and triacylglycerol (TG-rich emulsions (EM prepared with TG-fatty acids (FAs. TG-FAs of varying chain lengths and degrees of unsaturation were tested in the presence of a plasma fraction at d > 1.21 g/mL as the source of CE transfer protein. The transfer of CE from HDL to FED was greater than to FAST TG-rich acceptor lipoproteins, 18% and 14%, respectively. However, percent CE transfer from HDL to apoB-containing lipoproteins was similar for FED and FAST HDL. The CE transfer from HDL to EM depended on the EM TG-FA chain length. Furthermore, the chain length of the monounsaturated TG-containing EM showed a significant positive correlation of the CE transfer from HDL to EM (r = 0.81, P < 0.0001 and a negative correlation from EM to HDL (r = -041, P = 0.0088. Regarding the degree of EM TG-FAs unsaturation, among EMs containing C18, the CE transfer was lower from HDL to C18:2 compared to C18:1 and C18:3, 17.7%, 20.7%, and 20%, respectively. However, the CE transfer from EMs to HDL was higher to C18:2 than to C18:1 and C18:3, 83.7%, 51.2%, and 46.3%, respectively. Thus, the EM FA composition was found to be the rate-limiting factor regulating the transfer of CE from HDL. Consequently, the net transfer of CE between HDL and TG-rich particles depends on the specific arrangement of the TG acyl chains in the lipoprotein particle core.

  4. Observation of fine particle concentration and its chemical characteristics in central region of Korea during KORUS-AQ pre-campaign

    Science.gov (United States)

    Lyu, Y.; Lee, M.; Hwang, T.; Hong, Y.; Hong, J.

    2015-12-01

    The Central Region super site is one of the 6 super sites operated in Korean peninsula by Ministry of Environment Korea and monitor air quality of central district of Korea continuously and intensively. Located 160km south of Seoul, this site represents an urban site surrounded by residential, commercial area and an 8-lane road cross section which is one of the most crowed main roads in this area. This site also plays a significant role especially in tracing air pollutants flowing through the West Sea from China. During Korus-AQ(Korea-US Air Quality Study) pre-campaign conducted from 18th May to 12th June, PM2.5 and PM10 mass concentration using BAM1020 (MetOne), PM2.5bounded ion concentration using AIM (URG), metal concentrations using XRF (Cooper), organic and elemental carbon contents using SOCEC (Sunset), light scattering coefficient using Nephelometer (TSI) and meteorological parameters were continuously measured at this super site. PM2.5 and PM10 average concentrations were 31 and 49 ug/m3 with 0.63 fine to course ratio, which were relatively lower than those of annual average concentration of 2014 (39 and 58 ug/m3, respectively). The chemical composition of PM2.5 were determined as ion(46%), TC(37%), CM(2%), TM(0.1%) and unknown(15%). The average concentration of organic and elemental carbon were 5.6 and 1.8 ug/m3 which were similar lever to average of 2014 (5.9 ug/m3, 1.71 ug/m3, respectively). And the metal concentration including Pb(12.5 ng/m3), Fe(151.7 ng/m3), Ca(26.2 ng/m3), Ti(5.2 ng/m3), Cd(4.1 ng/m3) were significantly lower than those of 2014(31.4 ng/m3, 242.1 ng/m3, 167.9 ng/m3, 13.0 ng/m3, 8.3 ng/m3, respectively). However, the average concentration of sulfate was 6.3 ug/m3 which was 43% higher than that of 2014 (4.4 ug/m3). Overall aerosol and its component's concentrations except for secondary sulfate have been decreased since it was late spring and early summer in Korea during pre-campaign and usually in this season aerosol level is

  5. Concentration dependence of the light yield and energy resolution of NaI:Tl and CsI:Tl crystals excited by gamma, soft X-rays and alpha particles

    CERN Document Server

    Trefilova, L N; Kovaleva, L V; Zaslavsky, B G; Zosim, D I; Bondarenko, S K

    2002-01-01

    Based on the analysis of light yield dependence on activator concentration for NaI:Tl and CsI:Tl excited by gamma-rays, soft X-rays and alpha-particles, an explanation of the effect of energy resolution enhancement with the rise of Tl content has been proposed. Based on the concept regarding the electron track structure, we proposed an alternative explanation of the intrinsic resolution value. The concept does not take into account the non-proportional response to electrons of different energies and is based on the statistic fluctuation of scintillation photon number formed outside and inside the regions of higher ionization density.

  6. Plasmons on Separated Particles: Homogenization and Applications

    Science.gov (United States)

    McPhedran, Ross

    In this chapter, we discuss localized plasmons in optical systems containing metallic particles, clusters of metallic particles, or periodic arrays of metallic particles, separated in all cases by a background dielectric material or matrix. We begin with a brief discussion of the equations governing electromagnetic propagation in structured or composite systems containing metal particles in a matrix. A full electromagnetic solution for a periodic array of particles or a finite cluster of them is possible, but much can be learned from treatments in the quasistatic approximation, where properties of the particles are subsumed in effective dielectric permittivities and magnetic permeabilities, and these are used in Maxwells' equations for a homogeneous material to calculate reflection and transmission properties. The two most important equations used to calculate effective dielectric permittivities and magnetic permeabilities are the Maxwell-Garnett formula and Bruggeman's effective medium formulae. We compare these in Sect. 6.3, and look at applications in Sect. 6.4 to the field of selective absorbers for photothermal and photovoltaic energy applications. In the next section, we go on to consider collections of particles and their resonant properties, which can be exploited to deliver strong local concentrations of electromagnetic fields. These are used in Sects. 6.6 and 6.7 to discuss cloaking using plasmonic resonance, and spasers, devices which can overcome through amplification the propagation losses associated with plasmons.

  7. Air pollution particles and iron homeostasis | Science ...

    Science.gov (United States)

    Background: The mechanism underlying biological effects of particles deposited in the lung has not been defined. Major Conclusions: A disruption in iron homeostasis follows exposure of cells to all particulate matter including air pollution particles. Following endocytosis, functional groups at the surface of retained particle complex iron available in the cell. In response to a reduction in concentrations of requisite iron, a functional deficiency can result intracellularly. Superoxide production by the cell exposed to a particle increases ferrireduction which facilitates import of iron with the objective being the reversal of the metal deficiency. Failure to resolve the functional iron deficiency following cell exposure to particles activates kinases and transcription factors resulting in a release of inflammatory mediators and inflammation. Tissue injury is the end product of this disruption in iron homeostasis initiated by the