Sample records for atmospheric material particles

  1. Certification of a reference material of metal content in atmospheric particles deposited on filters.

    PubMed

    Oster, Caroline; Labarraque, Guillaume; Fisicaro, Paola

    2015-04-01

    Air quality is one of the areas in Europe where a series of EU Directives have been published with the aim of achieving improved long-term and harmonised air quality objectives across the European Union. This paper describes the production of a certified reference material, aiming to support QA/QC programmes of analytical laboratories in the framework of the air quality monitoring activities. The certified values are the As, Cd, Ni and Pb masses in PM10 particles deposited on quartz filters (CRM SL-MR-2-PSF-01). All the steps of the certification, i.e. the material characterisation, homogeneity and stability evaluation and uncertainty calculation, were performed according to the ISO guide 35 guidelines. The certification was conducted using the characterisation by a single method approach based on isotope dilution for cadmium, nickel, and lead and gravimetric standard addition calibration for arsenic associated with inductively coupled mass spectrometry (ICP-MS). The amounts of the four elements are in the range of the target values regulated by EU Directives. PMID:25260410

  2. Estimates of atmospheric particle emissions from bulk handling of dusty materials in Spanish Harbours

    NASA Astrophysics Data System (ADS)

    Martín, F.; Pujadas, M.; Artiñano, B.; Gómez-Moreno, F.; Palomino, I.; Moreno, N.; Alastuey, A.; Querol, X.; Basora, J.; Luaces, J. A.; Guerra, A.

    The objective of this paper is to show the methodology developed to estimate particle emissions from several typical activities of bulk handling in harbours. It is based on several field experiments carried out in the Harbour of Tarragona, where high time resolution monitors were deployed close to different areas of bulk solids handling operations. Monitors recorded particle concentrations and meteorological variables. A high-resolution dispersion model is used to estimate the emission rates that best fits the observations. Results were comparable to those obtained with the AP-42 (EPA). The new emission estimates are used as input for an emission model called EMIPORT. The model also employs AP-42 (EPA) emission factors as a complement. This work is one of the activities of the LIFE project called HADA (Herramienta Automática de Diagnóstico Ambiental or in English Automatic Tool for Environmental Diagnostic).

  3. Chemistry of Individual Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander

    2008-03-01

    Aerosols are widely recognized as key elements in atmospheric environment. Chemical and morphological data of individual particles are of crucial importance for understanding of their formation, reactions, atmospheric history and aging. Microprobe analytical techniques have been extensively used in the past to characterize the size, morphology, phase and composition of particles collected in field and laboratory studies. These technique coupled with an appropriate time-resolved aerosol sampling are capable of generating time-resolved single-particle data, which then can be used to follow in detail the time evolution of specific types of aerosols. In this presentation we give a summary of recent research projects carried out in our laboratory that demonstrates how the use of complementary microprobe methods provides new insights into the atmospheric reactions of aerosols, their physical and chemical transformations, and in particular how the obtained data can be utilized to define future directions in laboratory and field studies of aerosols.

  4. The atmosphere as particle detector

    NASA Technical Reports Server (NTRS)

    Stanev, Todor

    1990-01-01

    The possibility of using an inflatable, gas-filled balloon as a TeV gamma-ray detector on the moon is considered. By taking an atmosphere of Xenon gas there, or by extracting it on the moon, a layman's detector design is presented. In spite of its shortcomings, the exercise illustrates several of the novel features offered by particle physics on the moon.

  5. Chemical transformations of peptide containing fine particles: oxidative processing, accretion reactions and implications to the atmospheric fate of cell-derived materials in organic aerosol

    Microsoft Academic Search

    Scott Geddes; James Zahardis; Giuseppe A. Petrucci

    2009-01-01

    The atmospheric processing by ozone of peptide-containing mixed particles was investigated as proxies for biogenic and sea\\u000a spray primary organic aerosol. Reactions were performed in a flow reactor and particle composition was monitored by photoelectron\\u000a resonance capture ionization aerosol mass spectrometry. Mixed particles containing dipeptides in a saturated organic matrix\\u000a of stearic and palmitic acids showed no reaction under ozonolysis

  6. The Effects of Atmospheric Particles on Climate

    NSDL National Science Digital Library

    ThinkTV

    This video illustrates how atmospheric particles, or aerosols (such as black carbon, sulfates, dust, fog), can affect the energy balance of Earth regionally, and the implications for surface temperature warming and cooling.

  7. Vapor scavenging by atmospheric aerosol particles

    SciTech Connect

    Andrews, E.

    1996-05-01

    Particle growth due to vapor scavenging was studied using both experimental and computational techniques. Vapor scavenging by particles is an important physical process in the atmosphere because it can result in changes to particle properties (e.g., size, shape, composition, and activity) and, thus, influence atmospheric phenomena in which particles play a role, such as cloud formation and long range transport. The influence of organic vapor on the evolution of a particle mass size distribution was investigated using a modified version of MAEROS (a multicomponent aerosol dynamics code). The modeling study attempted to identify the sources of organic aerosol observed by Novakov and Penner (1993) in a field study in Puerto Rico. Experimentally, vapor scavenging and particle growth were investigated using two techniques. The influence of the presence of organic vapor on the particle`s hydroscopicity was investigated using an electrodynamic balance. The charge on a particle was investigated theoretically and experimentally. A prototype apparatus--the refractive index thermal diffusion chamber (RITDC)--was developed to study multiple particles in the same environment at the same time.

  8. Particle Size Distributions in Atmospheric Clouds

    NASA Technical Reports Server (NTRS)

    Paoli, Roberto; Shariff, Karim

    2003-01-01

    In this note, we derive a transport equation for a spatially integrated distribution function of particles size that is suitable for sparse particle systems, such as in atmospheric clouds. This is done by integrating a Boltzmann equation for a (local) distribution function over an arbitrary but finite volume. A methodology for evolving the moments of the integrated distribution is presented. These moments can be either tracked for a finite number of discrete populations ('clusters') or treated as continuum variables.

  9. Nanoporous Materials in Atmosphere Revitalization. Chapter 1

    NASA Technical Reports Server (NTRS)

    Hernandez-Maldonado, J.; Ishikawa, Yasuyuki; Luna, Bernadette; Junaedi, Christian; Mulloth, Lila; Perry, Jay L.; Raptis, Raphael G.; Roychoudhury, Subir

    2012-01-01

    Atmospheric Revitalization (AR) is the term the National Aeronautics and Space Administration (NASA) uses to encompass the engineered systems that maintain a safe, breathable gaseous atmosphere inside a habitable space cabin. An AR subsystem is a key part of the Environmental Control and Life Support (ECLS) system for habitable space cabins. The ultimate goal for AR subsystem designers is to 'close the loop', that is, to capture gaseous human metabolic products, specifically water vapor (H2O) and Carbon dioxide (CO2), for maximal Oxygen (o2) recovery and to make other useful resources from these products. The AR subsystem also removes trace chemical contaminants from the cabin atmosphere to preserve cabin atmospheric quality, provides O2 and may include instrumentation to monitor cabin atmospheric quality. Long duration crewed space exploration missions require advancements in AR process technologies in order to reduce power consumption and mass and to increase reliability compared to those used for shorter duration missions that are typically limited to Low Earth Orbit. For example, current AR subsystems include separate processors and process air flow loops for removing metabolic CO2 and volatile organic tract contaminants (TCs). Physical adsorbents contained in fixed, packed beds are employed in these processors. Still, isolated pockets of high carbon dioxide have been suggested as a trigger for crew headaches and concern persists about future cabin ammonia (NH3) levels as compared with historical flights. Developers are already focused on certain potential advancements. ECLS systems engineers envision improving the AR subsystem by combining the functions of TC control and CO2 removal into a single regenerable process and moving toward structured sorbents - monoliths - instead of granular material. Monoliths present a lower pressure drop and eliminate particle attrition problems that result from bed containment. New materials and configurations offer promise for lowering cabin levels of CO2 and NH3 as well as reducing power requirements and increasing reliability. This chapter summarizes the challenges faced by ECLS system engineers in pursuing these goals, and the promising materials developments that may be part of the technical solution for challenges of crewed space exploration beyond LEO.

  10. Energetic Particle Precipitation in the Martian Atmosphere: Expectations for MAVEN

    NASA Astrophysics Data System (ADS)

    Jolitz, R. D.; Lillis, R.; Curry, S.; Larson, D.; Jakosky, B.

    2014-07-01

    Energetic charged particle precipitation is an important process in the martian upper atmosphere. Energetic particle effect measurement and models at Mars are scarce. We developed a Monte Carlo code to track a population of ions in an atmosphere.

  11. ATMOSPHERIC PROCESSES AND EFFECTS ON MATERIALS

    EPA Science Inventory

    These two chapters summarize the effects expected from the depletion of stratospheric ozone by the presence of CFCs. he two areas considered by these two reports are materials damage and atmospheric processes. ncreased UV can affect materials in the following ways: (1) corrosion ...

  12. Characterization of individual complex particles in urban atmospheric environment

    NASA Astrophysics Data System (ADS)

    Suzuki, K.; Takii, T.; Tomiyasu, B.; Nihei, Y.

    2006-07-01

    The origins of carrier particles of complex particles (iron-rich particles) collected from the urban atmospheric environment near to road traffic and a railroad were investigated from the detailed surface information using FE-SEM/EDS and TOF-SIMS analyses. From the FE-SEM/EDS analyses, the iron-rich particles were classified into two typical types (spherical type and non-spherical type). From the TOF-SIMS measurements, the characteristic secondary ions of spherical type of iron-rich particles were 23Na + and 39K +. The minor components of non-spherical type were Al, Ca and Ba. On the other hand, we carried out TOF-SIMS measurement to materials of rail origin and brake origin. From the comparison of these spectra pattern, it seemed that the spherical type of iron-rich particles was emitted from the rail origin. We concluded that the origin of non-spherical type of iron-rich particles were brake pad of vehicles.

  13. Images reveal that atmospheric particles can undergo liquid-liquid phase separations

    SciTech Connect

    You, Yuan; Renbaum-Wolff, Lindsay; Carreras-Sospedra, Marc; Hanna, Sarah; Hiranuma, Naruki; Kamal, Saeid; Smith, Mackenzie L.; Zhang, Xiaolu; Weber, Rodney; Shilling, John E.; Dabdub, Donald; Martin, Scot T.; Bertram, Allan K.

    2012-07-30

    A large fraction of submicron atmospheric particles contains both organic material and inorganic salts. As the relative humidity cycles in the atmosphere, these mixed particles can undergo a range of phase transitions, possibly including liquid-liquid phase separation. If liquid-liquid phase separation occurs, the gas-particle partitioning of atmospheric semi-volatile organic compounds, the scattering and absorption of solar radiation, and the uptake of reactive gas species on atmospheric particles will be affected, with important implications for climate predictions. The actual occurrence of these types of phase transitions within individual atmospheric particles has been considered uncertain, in large part because of the absence of observations for real-world samples. Here, using optical and fluorescence microscopy, we observe the coexistence of two non-crystalline phases in particles generated from real-world samples collected on multiple days in Atlanta, Georgia, and in particles generated in the laboratory using atmospheric conditions. These results reveal that atmospheric particles can undergo liquid-liquid phase separations. Using a box model, we show that liquid-liquid phase separation can result in increased concentrations of gas-phase NO3 and N2O5 in the Atlanta region, due to decreased particle uptake of N2O5.

  14. Chemistry and Composition of Atmospheric Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Kolb, Charles E.; Worsnop, Douglas R.

    2012-05-01

    For more than two decades a cadre of physical chemists has focused on understanding the formation processes, chemical composition, and chemical kinetics of atmospheric aerosol particles and droplets with diameters ranging from a few nanometers to ˜10,000 nm. They have adapted or invented a range of fundamental experimental and theoretical tools to investigate the thermochemistry, mass transport, and chemical kinetics of processes occurring at nanoscale gas-liquid and gas-solid interfaces for a wide range of nonideal, real-world substances. State-of-the-art laboratory methods devised to study molecular spectroscopy, chemical kinetics, and molecular dynamics also have been incorporated into field measurement instruments that are deployed routinely on research aircraft, ships, and mobile laboratories as well as at field sites from megacities to the most remote jungle, desert, and polar locations. These instruments can now provide real-time, size-resolved aerosol particle physical property and chemical composition data anywhere in Earth's troposphere and lower stratosphere.

  15. Wear of hard materials by hard particles

    SciTech Connect

    Hawk, Jeffrey A.

    2003-10-01

    Hard materials, such as WC-Co, boron carbide, titanium diboride and composite carbide made up of Mo2C and WC, have been tested in abrasion and erosion conditions. These hard materials showed negligible wear in abrasion against SiC particles and erosion using Al2O3 particles. The WC-Co materials have the highest wear rate of these hard materials and a very different material removal mechanism. Wear mechanisms for these materials were different for each material with the overall wear rate controlled by binder composition and content and material grain size.

  16. Meteoric Material: An Important Component of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Grebowsky, Joseph M.; Moses, Julianne I.; Pesnell, W. Dean; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    Interplanetary dust particles (IDPs) interact with all planetary atmospheres and leave their imprint as perturbations of the background atmospheric chemistry and structure. They lead to layers of metal ions that can become the dominant positively charged species in lower ionospheric regions. Theoretical models and radio occultation measurements provide compelling evidence that such layers exist in all planetary atmospheres. In addition IDP ablation products can affect neutral atmospheric chemistry, particularly at the outer planets where the IDPs supply oxygen compounds like water and carbon dioxide to the upper atmospheres. Aerosol or smoke particles from incomplete ablation or recondensation of ablated IDP vapors may also have a significant impact on atmospheric properties.

  17. Capture of Meteoric Material by Mesospheric Ice Particles

    NASA Astrophysics Data System (ADS)

    Gumbel, J.; Megner, L. S.; Hedin, J.

    2013-12-01

    In the Earth's polar summer mesosphere, the co-existence of ice and meteoric material gives rise to complex particle processes. A charge-dependent coagulation model has been developed to describe the interaction between these mesospheric players. Substantial capture rates are found for both metal atoms and smoke particles of meteoric origin. This results in a local atmospheric depletion of meteoric material and a typical mass mixing ratios of 0.1% to 1% meteoric material in the ice. This affects both charging properties and optical properties of noctilucent clouds and related particle phenomena. Open questions concern the "processing" of the meteoric material in the ice and the fate of accumulated metal species and charges upon ice sublimation at the end of the life cycle of mesospheric clouds.

  18. Source contributions to atmospheric fine carbon particle concentrations

    Microsoft Academic Search

    H. Andrew Gray; Glen R. Cass

    1998-01-01

    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

  19. Charged and Neutral Particle Interactions on Aerospace Materials

    SciTech Connect

    Singleterry, R.C. Jr.; Thibeault, Sheila A. [NASA Langley Research Center, Hampton, VA 23681 (United States); Wilkins, Richard; Huff, Harold [Center for Applied Radiation Research, Prairie View A and M University, Prairie View, TX 77446 (United States)

    2002-07-01

    Various candidate aircraft and spacecraft materials were analyzed and compared in a neutron environment using the Monte Carlo N-Particle (MCNP) transport code and in Galactic Cosmic Ray (GCR) and Trapped environments using the HZETRN code. These candidate materials are being used in aerospace vehicles, have been tested in particle beams, or seemed reasonable to analyze in this manner before deciding to manufacture and test them. This analysis shows that hydrogen bearing materials are better than the metal alloys for reducing the number of reflected and transmitted particles. It also shows that neutrons above 1 MeV are reflected out of the face of the slab better when larger quantities of carbon are present in the material. If a neutron absorber is added to the material, fewer neutrons are transmitted through and reflected from the material. This analysis focused on combinations of scatterers and absorbers to optimize these reaction channels on the higher energy neutron component. The absorber addition did not substantially change the charged particle transmission from the value obtained for polyethylene. The ultimate goal of this type of analysis is the selection of a layered material or material type that will optimize dose, dose equivalent, and electronic error rates inside the vehicle (and outside the vehicle if necessary for the mission). This analysis focuses on how the different material types and additives behave in the atmospheric and space related particle fields. As a secondary issue, as the amount of hydrogen bearing materials increase, larger fluxes of thermal neutrons are expected. It has been observed experimentally that large thicknesses of hydrogen bearing materials increase the error rates per neutron that occurs in SRAM memory chips. This effect is still being investigated, but it has been narrowed down to the larger mean neutron energy produced by the hydrogen bearing material. (authors)

  20. Stereochemical transfer to atmospheric aerosol particles accompanying the oxidation of biogenic volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Ebben, Carlena J.; Zorn, Soeren R.; Lee, Seung-Bok; Artaxo, Paulo; Martin, Scot T.; Geiger, Franz M.

    2011-08-01

    Asymmetric emission profiles of the stereoisomers of plant-derived volatile organic compounds vary with season, geography, plant type, and stress factors. After oxidation of these compounds in the atmosphere, the low-vapor pressure products ultimately contribute strongly to the particle-phase material of the atmosphere. In order to explore the possibility of stereochemical transfer to atmospheric aerosol particles during the oxidation of biogenic volatile organic compounds, second-order coherent vibrational spectra were recorded of the particle-phase organic material produced by the oxidation of different stereoisomeric mixes of ?-pinene. The spectra show that the stereochemical configurations are not scrambled but instead are transferred from the gas-phase molecular precursors to the particle-phase molecules. The spectra also show that oligomers formed in the particle phase have a handed superstructure that depends strongly and nonlinearly on the initial stereochemical composition of the precursors. Because the stereochemical mix of the precursors for a material can influence the physical and chemical properties of that material, our findings suggest that chirality is also important for such properties of plant-derived aerosol particles.

  1. Designing Jammed Materials from the Particle Up

    NASA Astrophysics Data System (ADS)

    Miskin, Marc

    2015-03-01

    Identifying which microscopic features produce a desired macroscopic behavior is a problem at the forefront of materials science. This task is materials design, and within it, new challenges have emerged from tailoring packings of particles jammed into a rigid state. For these materials, particle shape is a key parameter by which the response of a packing can be tuned. Yet designing via shape faces two unique complications: first there is no general theory that calculates the response of an aggregate given a particle shape, and second, there is no straightforward way to explore the space of all particle geometries. This talk summarizes recent results that address these challenges to design jammed materials from the particle up. It shows how simulations, experiments, and state-of-the-art optimization engines come together to form a complete system that identifies extreme materials. As examples, it will show how this system can create particle shapes that form the stiffest, softest, densest, loosest, most dissipative and strain-stiffening aggregates. Finally, it will discuss the how these results relate to the general task of materials design and the exciting possibilities associated with optimizing, tuning and rationally constructing new breeds of jammed materials.

  2. AstroParticles & Atmosphere, Paris May 2003John Matthews Monitoring the Aerosol Phase

    E-print Network

    AstroParticles & Atmosphere, Paris May 2003John Matthews Monitoring the Aerosol Phase Function University of New Mexico #12;AstroParticles & Atmosphere, Paris May 2003John Matthews #12;AstroParticles & Atmosphere, Paris May 2003John Matthews #12;AstroParticles & Atmosphere, Paris May 2003John Matthews #12

  3. Measurement of the nucleation of atmospheric aerosol particles.

    PubMed

    Kulmala, Markku; Petäjä, Tuukka; Nieminen, Tuomo; Sipilä, Mikko; Manninen, Hanna E; Lehtipalo, Katrianne; Dal Maso, Miikka; Aalto, Pasi P; Junninen, Heikki; Paasonen, Pauli; Riipinen, Ilona; Lehtinen, Kari E J; Laaksonen, Ari; Kerminen, Veli-Matti

    2012-09-01

    The formation of new atmospheric aerosol particles and their subsequent growth have been observed frequently at various locations all over the world. The atmospheric nucleation rate (or formation rate) and growth rate (GR) are key parameters to characterize the phenomenon. Recent progress in measurement techniques enables us to measure atmospheric nucleation at the size (mobility diameter) of 1.5 (±0.4) nm. The detection limit has decreased from 3 to 1 nm within the past 10 years. In this protocol, we describe the procedures for identifying new-particle-formation (NPF) events, and for determining the nucleation, formation and growth rates during such events under atmospheric conditions. We describe the present instrumentation, best practices and other tools used to investigate atmospheric nucleation and NPF at a certain mobility diameter (1.5, 2.0 or 3.0 nm). The key instruments comprise devices capable of measuring the number concentration of the formed nanoparticles and their size, such as a suite of modern condensation particle counters (CPCs) and air ion spectrometers, and devices for characterizing the pre-existing particle number concentration distribution, such as a differential mobility particle sizer (DMPS). We also discuss the reliability of the methods used and requirements for proper measurements and data analysis. The time scale for realizing this procedure is 1 year. PMID:22899333

  4. [Distribution of atmospheric ultrafine particles during haze weather in Hangzhou].

    PubMed

    Chen, Qiu-Fang; Sun, Zai; Xie, Xiao-Fang

    2014-08-01

    Atmospheric ultrafine particles (UFPs) were monitored with fast mobility particle sizer (FMPS) in continuous haze weather and the haze fading process during December 6 to 11, 2013 in Hangzhou. Particle concentration and size distribution were studied associated with meteorological factors. The results showed that number concentrations were the highest at night and began to reduce in the morning. There was a small peak at 8 o'clock in the morning and 18 o'clock in the afternoon. It showed an obvious peak traffic source, which indicated that traffic emissions played a great role in the atmospheric pollution. During haze weather, the highest number concentration of UFPs reached 8 x 10(4) cm(-3). Particle size spectrum distribution was bimodal, the peak particle sizes were 15 nm and 100 nm respectively. Majority of UFPs were Aitken mode and Accumulation mode and the size of most particles concentrated near 100 nm. Average CMD(count medium diameter) was 85.89 nm. During haze fading process, number concentration and particles with size around 100 nm began to reduce and peak size shifted to small size. Nuclear modal particles increased and were more than accumulation mode. Average CMD was 58.64 nm. Meteorological factors such as the visibility and wind were negatively correlated with the particle number concentration. Correlation coefficient R were -0.225 and - 0.229. The humidity was correlated with number concentration. Correlation coefficient R was 0.271. The atmosphere was stable in winter and the level temperature had small correlation with number concentration. Therefore, study on distribution of atmospheric ultrafine particles during haze weather had the significance on the formation mechanism and control of haze weather. PMID:25338351

  5. Evolution of Soot Particle Morphology and Mixing State in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Mazzoleni, C.; China, S.; Sharma, N.; Gorkowski, K.; Dubey, M.; Aiken, A. C.; Zaveri, R. A.; Salvadori, N.; Chakrabarty, R. K.; Moosmuller, H.; Onasch, T. B.; Herndon, S.; Williams, L. R.; Liu, S.; Dzepina, K.; Helmig, D.; Hueber, J.; Fialho, P. J.; Mazzoleni, L. R.; kumar, S.; Dziobak, M.; Wright, K.

    2013-12-01

    Soot particles (aka black carbon) impact the environment and climate by affecting Earth's radiation balance, cloud microphysics, and atmospheric chemistry. The complex morphology and mixing state of soot particles influence their optical properties and therefore their radiative forcing, the particles' transport, lifecycle, and heterogeneous chemistry. How soot morphology and mixing state alter during transport from the source to remote areas is still not well understood. While aging, soot particles can change shape, oxidize and mix, and become coated by organic and inorganic materials. In this study, we investigate the morphological and mixing state evolution of single soot particles in different stages of their 'life' in the atmosphere. This analysis will include an overview of several samples collected in various locations and atmospheric conditions: 1) particles freshly emitted near freeway on-ramps in Southern Michigan (USA); 2) particles emitted in two biomass burning events in New Mexico (USA), one close to the sampling location and another hundreds of miles away; 3) particles in the urban atmosphere of Mexico City and in the uplifted boundary layer captured on the top of the Pico de Tres Padres Mountain (on the north edge of Mexico City); 4) particles collected in the Sacramento urban area and the Sierra Nevada foothills (CA, USA); 5) particles collected in Detling (UK), and mostly transported from London, and 6) long-range transported particles in the free troposphere and collected at the Pico Mountain Observatory, located near the top of the Pico Volcano in the Azores (Portugal). We analyzed a large number of individual particles using electron microscopy and X-ray spectroscopy followed by image analysis. The projected structural properties of soot particles were characterized using size (maximum length, maximum width, and area equivalent diameter) and shape descriptors (e.g., aspect ratio, roundness, and convexity). The particle mass-fractal dimensions were determined using the ensemble method. The mixing state was analyzed by classifying soot particles based on visual inspection of coating and morphology. Soot particles freshly emitted by anthropogenic sources show less coating and more open chain-like structures; on the other hand biomass burning and long-range transported soot particles appear to be mostly coated and exhibit very compacted shapes. However, soot processing in urban atmospheres results in a complex mixture of coated and uncoated particles with a variety of morphologies and mixing states.

  6. What controls atmospheric particle sizes over the Greenland ice sheet?

    NASA Astrophysics Data System (ADS)

    Erhardt, Tobias; Fischer, Hubertus; Wagenbach, Dietmar

    2015-04-01

    Insoluble particle concentrations and their size distributions are routinely measured in polar ice cores to reconstruct past atmospheric dust loads and often interpreted in terms of changes in atmospheric transport. However the transfer of mineral dust particles from the atmosphere to the ice is not well understood, especially regarding the preserved particle size distributions (PSDs). Here we present an extension to a conceptual deposition model for aerosols based on precipitation scavenging and gravitational settling including the size distribution of the particles. The extended model can be used to study the effect of different atmospheric PSDs and changes in accumulation rate on the persevered particle concentration and their size distribution. It can also be applied to reconstruct past atmospheric dust conditions using accumulation rate reconstructions and measured PSDs. We apply the model to previously published size distribution data from North GRIP (Greenland) to investigate the influence of the changing deposition regime during the fast transitions between stadial and interstadial conditions during the last glacial. For these transitions reconstructed accumulation rates show changes by a factor of two with low accumulation rates during cold and high accumulation rates during warm periods . In general the transfer to the ice core shifts the particle size distributions towards larger particles. This effect is more pronounced for lower accumulation sites where dry deposition dominates. For sites with accumulation rates comparable to NGRIP variability in the accumulation rate has a small influence on the PSDs in the ice. However for low accumulation sites, such as in central Antarctica, changes in accumulation rate can have a large impact on the preserved PSDs.

  7. Dispersion of aerosol particles in the atmosphere: Fukushima

    NASA Astrophysics Data System (ADS)

    Haszpra, Tímea; Lagzi, István; Tél, Tamás

    2013-04-01

    Investigation of dispersion and deposition of aerosol particles in the atmosphere is an essential issue, because they have an effect on the biosphere and atmosphere. Moreover, aerosol particles have different transport properties and chemical and physical transformations in the atmosphere compared to gas phase air pollutants. The motion of a particle is described by a set of ordinary differential equations. The large-scale dynamics in the horizontal direction can be described by the equations of passive scalar advection, but in the vertical direction a well-defined terminal velocity should be taken into account as a term added to the vertical wind component. In the planetary boundary layer turbulent diffusion has an important role in the particle dispersion, which is taken into account by adding stochastic terms to the deterministic equations above. Wet deposition is also an essential process in the lower levels of the atmosphere, however, its precise parameterization is a challenge. For the simulations the wind field and other necessary data were taken from the ECMWF ERA-Interim database. In the case of the Fukushima Daiichi nuclear disaster (March-April 2011) radioactive aerosol particles were also released in the planetary boundary layer. Simulations (included the continuous and varying emission from the nuclear power plant) will be presented for the period of 14-23 March. Results show that wet deposition also has to be taken into consideration in the lower levels of the atmosphere. Furthermore, dynamical system characteristics are evaluated for the aerosol particle dynamics. The escape rate of particles was estimated both with and without turbulent diffusion, and in both cases when there was no wet deposition and also when wet deposition was taken into consideration.

  8. Impact of particle formation on atmospheric ions and particle number concentrations in an urban environment

    NASA Astrophysics Data System (ADS)

    Cheung, H. C.; Chou, C. C.-K.; Jayaratne, E. R.; Morawska, L.

    2015-04-01

    A measurement campaign was conducted from 3 to 19 December 2012 at an urban site of Brisbane, Australia. Size distribution of ions and particle number concentrations were measured to investigate the influence of particle formation and biomass burning on atmospheric ion and particle concentrations. Overall ion and particle number concentrations during the measurement period were found to be (- 1.2 × 103 cm- 3 | + 1.6 × 103 cm- 3) and 4.4 × 103, respectively. The results of correlation analysis between concentrations of ions and nitrogen oxides indicated that positive and negative ions originated from similar sources, and that vehicle exhaust emissions had a more significant influence on intermediate/large ions, while cluster ions rapidly attached to larger particles once emitted into the atmosphere. Diurnal variations in ion concentration suggested the enrichment of intermediate and large ions on new particle formation event days, indicating that they were involved in the particle formation processes. Elevated total ions, particularly larger ions, and particle number concentrations were found during biomass burning episodes. This could be due to the attachment of cluster ions onto accumulation mode particles or production of charged particles from biomass burning, which were in turn transported to the measurement site. The results of this work enhance scientific understanding of the sources of atmospheric ions in an urban environment, as well as their interactions with particles during particle formation processes.

  9. Optical properties, morphology and elemental composition of atmospheric particles at T1 supersite on MILAGRO campaign

    NASA Astrophysics Data System (ADS)

    Carabali, G.; Mamani-Paco, R.; Castro, T.; Peralta, O.; Herrera, E.; Trujillo, B.

    2012-03-01

    Atmospheric particles were sampled at T1 supersite during MILAGRO campaign, in March 2006. T1 was located at the north of Mexico City (MC). Aerosol sampling was done by placing copper grids for Transmission Electron Microscope (TEM) on the last five of an 8-stage MOUDI cascade impactor. Samples were obtained at different periods to observe possible variations on morphology. Absorption and scattering coefficients, as well as particle concentrations (0.01-3 ?m aerodynamic diameter) were measured simultaneously using a PSAP absorption photometer, a portable integrating nephelometer, and a CPC particle counter. Particle images were acquired at different magnifications using a CM 200 Phillips TEM-EDAX system, and then calculated the border-based fractal dimension. Also, Energy Dispersive X-Ray Spectroscopy (EDS) was used to determine the elemental composition of particles. The morphology of atmospheric particles for two aerodynamic diameters (0.18 and 1.8 ?m) was compared using border-based fractal dimension to relate it to the other particle properties, because T1-generated particles have optical, morphological and chemical properties different from those transported by the MC plume. Particles sampled under MC pollution influence showed not much variability, suggesting that more spherical particles (border-based fractal dimension close to 1.0) are more common in larger sizes (d50 = 1.8 ?m), which may be attributed to aerosol aging and secondary aerosol formation. Between 06:00 and 09:00 a.m., smaller particles (d50 = 0.18 ?m) had more irregular shapes resulting in higher border-based fractal dimensions (1.2-1.3) for samples with more local influence. EDS analysis in d50 = 0.18 ?m particles showed high contents of carbonaceous material, Si, Fe, K, and Co. Perhaps, this indicates an impact from industrial and vehicle emissions on atmospheric particles at T1.

  10. Submicron particle characteristics of atmospheres in a long highway tunnel.

    PubMed

    Hwa, Mei-Yin; Yu, Tai-Yi

    2014-10-01

    This study used a scanning mobility particle sizer (SMPS) to measure and categorize submicron atmospheric particles in the 14-737-nm size range for ambient and urban roadside air and for air in the Hsuehshan Tunnel (12.9 km), Taiwan. Principal component analysis, traffic flow, and particle size distributions were used to identify the emission characteristics of light-duty vehicles (LDV) with the SMPS data. In the Hsuehshan Tunnel, the particle size from the majority of emissions discharged by LDV is approximately 20-60 nm, and the maximum particle number can reach up to 2.5?×?10(5). In contrast, submicron particle size distribution for urban roadsides is mostly 14-200 nm, and the maximum particle number is approximately 4?×?10(4) with the particle number for most particle sizes being below 1,200. The submicron particle size distribution at the ambient air station was unimodal with a mode sizes at 30-50 nm with the maximum particle number of 3,000. PMID:24939711

  11. Heterogeneous ice nucleation and water uptake by field-collected atmospheric particles below 273 K

    NASA Astrophysics Data System (ADS)

    Wang, Bingbing; Laskin, Alexander; Roedel, Tobias; Gilles, Mary K.; Moffet, Ryan C.; Tivanski, Alexei V.; Knopf, Daniel A.

    2011-11-01

    Ice formation induced by atmospheric particles through heterogeneous nucleation is not well understood. Onset conditions for heterogeneous ice nucleation and water uptake by particles collected in Los Angeles and Mexico City were determined as a function of temperature (200-273 K) and relative humidity with respect to ice (RHice). Four dominant particle types were identified including soot associated with organics, soot with organic and inorganics, inorganic particles of marine origin coated with organic material, and Pb/Zn-containing particles apportioned to emissions relevant to waste incineration. Single particle characterization was provided by micro-spectroscopic analyses using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Above 230 K, significant differences in onsets of water uptake and immersion freezing of different particle types were observed. Below 230 K, particles exhibited high deposition ice nucleation efficiencies and formed ice atRHicewell below homogeneous ice nucleation limits. The data suggest that water uptake and immersion freezing are more sensitive to changes in particle chemical composition compared to deposition ice nucleation. The data demonstrate that anthropogenic and marine influenced particles, exhibiting various chemical and physical properties, possess distinctly different ice nucleation efficiencies and can serve as efficient IN at atmospheric conditions typical for cirrus and mixed-phase clouds.

  12. Heterogeneous ice nucleation and water uptake by field-collected atmospheric particles below 273 K

    NASA Astrophysics Data System (ADS)

    Wang, Bingbing; Laskin, Alexander; Roedel, Tobias; Gilles, Mary K.; Moffet, Ryan C.; Tivanski, Alexei V.; Knopf, Daniel A.

    2012-09-01

    Ice formation induced by atmospheric particles through heterogeneous nucleation is not well understood. Onset conditions for heterogeneous ice nucleation and water uptake by particles collected in Los Angeles and Mexico City were determined as a function of temperature (200-273 K) and relative humidity with respect to ice (RHice). Four dominant particle types were identified including soot associated with organics, soot with organic and inorganics, inorganic particles of marine origin coated with organic material, and Pb/Zn-containing particles apportioned to emissions relevant to waste incineration. Single particle characterization was provided by micro-spectroscopic analyses using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Above 230 K, significant differences in onsets of water uptake and immersion freezing of different particle types were observed. Below 230 K, particles exhibited high deposition ice nucleation efficiencies and formed ice atRHicewell below homogeneous ice nucleation limits. The data suggest that water uptake and immersion freezing are more sensitive to changes in particle chemical composition compared to deposition ice nucleation. The data demonstrate that anthropogenic and marine influenced particles, exhibiting various chemical and physical properties, possess distinctly different ice nucleation efficiencies and can serve as efficient IN at atmospheric conditions typical for cirrus and mixed-phase clouds.

  13. Deposition of atmospheric mineral particles in the North Pacific Ocean

    Microsoft Academic Search

    Mitsuo Uematsu; Robert A. Duce; Joseph M. Prospero

    1985-01-01

    Total deposition of atmospheric mineral particles (wet plus dry) has been measured during consecutive two-week sampling intervals from January, 1981 to March, 1982 at four island stations (Midway, Oahu, Enewetak, and Fanning) of the SEAREX Asian Dust Study Network in the North Pacific. The total deposition of mineral aerosol during the period from February to June is higher than that

  14. Atmospheric Condensational Properties of Ultrafine Chain and Fractal Aerosol Particles

    NASA Technical Reports Server (NTRS)

    Marlow, William H.

    1997-01-01

    The purpose for the research sponsored by this grant was to lay the foundations for qualitative understanding and quantitative description of the equilibrium vapor pressure of water vapor over the irregularly shaped, carbonaceous particles that are present in the atmosphere. This work apparently was the first systematic treatment of the subject. Research was conducted in two complementary components: 1. Calculations were performed of the equilibrium vapor pressure of water over particles comprised of aggregates of spheres in the 50-200 nm radius range. The purposes of this work were two-fold. First, since no systematic treatment of this subject had previously been conducted, its availability would be directly useful for quantitative treatment for a limited range of atmospheric aerosols. Second, it would provide qualitative indications of the effects of highly irregular particle shape on equilibrium vapor pressure of aggregates comprised of smaller spheres.

  15. Methods for characterization of organic compounds in atmospheric aerosol particles.

    PubMed

    Parshintsev, Jevgeni; Hyötyläinen, Tuulia

    2015-08-01

    Atmospheric aerosol particles of primary or secondary, biogenic or anthropogenic origin are highly complex samples of changing composition in time and space. To assess their effects on climate or human health, the size-dependent chemical composition of these ubiquitous atmospheric constituents must be known. The development of novel analytical methods has enabled more detailed characterization of the organic composition of aerosols. This review gives an overview of the methods used in the chemical characterization of atmospheric aerosol particles, with a focus on mass-spectrometry techniques for organic compounds, either alone or in combination with chromatographic separation. Off-line, on-site, and on-line methods are covered, and the advantages and limitations of the different methods are discussed. The main emphasis is on methods used for detailed characterization of the composition of the organic compounds in aerosol particles. We address and summarize the current state of analytical methods used in aerosol research and discuss the importance of developing novel sampling strategies and analytical instrumentation. Graphical Abstract Challenges in the atmospheric aerosol analytics. PMID:25542579

  16. Particle motion in atmospheric boundary layers of Mars and Earth

    NASA Technical Reports Server (NTRS)

    White, B. R.; Iversen, J. D.; Greeley, R.; Pollack, J. B.

    1975-01-01

    To study the eolian mechanics of saltating particles, both an experimental investigation of the flow field around a model crater in an atmospheric boundary layer wind tunnel and numerical solutions of the two- and three-dimensional equations of motion of a single particle under the influence of a turbulent boundary layer were conducted. Two-dimensional particle motion was calculated for flow near the surfaces of both Earth and Mars. For the case of Earth both a turbulent boundary layer with a viscous sublayer and one without were calculated. For the case of Mars it was only necessary to calculate turbulent boundary layer flow with a laminar sublayer because of the low values of friction Reynolds number; however, it was necessary to include the effects of slip flow on a particle caused by the rarefied Martian atmosphere. In the equations of motion the lift force functions were developed to act on a single particle only in the laminar sublayer or a corresponding small region of high shear near the surface for a fully turbulent boundary layer. The lift force functions were developed from the analytical work by Saffman concerning the lift force acting on a particle in simple shear flow.

  17. The atmospheric radiation response to solar-particle-events.

    PubMed

    O'Brien, K; Sauer, H H

    2003-01-01

    High-energy solar particles, produced in association with solar flares and coronal mass ejections, occasionally bombard the earth's atmosphere. resulting in radiation intensities additional to the background cosmic radiation. Access of these particles to the earth's vicinity during times of geomagnetic disturbances are not adequately described by using static geomagnetic field models. These solar fluxes are also often distributed non uniformly in space, so that fluxes measured by satellites obtained at great distances from the earth and which sample large volumes of space around the earth cannot be used to predict fluxes locally at the earth's surface. We present here a method which uses the ground-level neutron monitor counting rates as adjoint sources of the flux in the atmosphere immediately above them to obtain solar-particle effective dose rates as a function of position over the earth's surface. We have applied this approach to the large September 29-30, 1989 ground-level event (designated GLE 42) to obtain the magnitude and distribution of the solar-particle effective dose rate from an atypically large event. The results of these calculations clearly show the effect of the softer particle spectra associated with solar particle events, as compared with galactic cosmic rays, results in a greater sensitivity to the geomagnetic field, and, unlike cosmic rays, the near-absence of a "knee" near 60 degrees geomagnetic latitude. PMID:14727666

  18. Multiple Accelerating Potential SEM Microanalysis of Individual Atmospheric Particles (Invited)

    NASA Astrophysics Data System (ADS)

    Armstrong, J. T.

    2009-12-01

    There are many significant applications of individual micro- or nano-particle characterization in aerosol and atmospheric sciences, as recent AGU sessions and topical meetings of organizations like the Microbeam Analysis Society have shown. Interpreting the results of individual particle analyses is complicated by the complexity of the matrix corrections involved and the compositional variability of the particles themselves. Even nano-particles can be composites of multiple phases. And due to their large surface areas, particle properties can be dominated by their surface coatings or agglomerations. One way to efficiently characterize such multi-phase objects (for particles larger than ~100 nm) is to utilize multiple accelerating potential (MAP) imaging and x-ray analysis in a high-resolution SEM. Changing the electron beam energy in several steps from 15-20 down to 1-3 keV emphasizes surface features in the electron imaging and reduces the analytical penetration from the µm to nm range. Existing thin-film algorithmic and Monte Carlo microprobe correction procedures can be adapted to correct the analytical data for particle geometric effects. The compositions of surface layers and under-layers can be separated and accurately determined. The results of this non-destructive method compares well in both surface sensitivity and accuracy to other surface-microanalytical techniques involving ion sputtering depth profiling. We have used MAP-SEM analysis to determine the thickness of surface layers thinner than 1 nm and the composition of multi-element surface coatings less than 10 nm thick. We will show examples of multiple accelerating potential analyses for the characterization of complex 1-10 µm atmospheric particles and discuss the practical implementation of algorithmic and Monte Carlo corrections for particle x-ray emission data.

  19. DERIVATION OF DAMAGE FUNCTIONS FOR ATMOSPHERIC DEGRADATION OF MATERIALS

    EPA Science Inventory

    The information in the pape is directed to those who develop and use damage functions which relate atmospheric degradation of materials to various causal agents in the atmosphere. Such relationships must be quantified mathematically as part of the overall cost-benefit considerati...

  20. Internally mixed atmospheric aerosol particles: Hygroscopic growth and light scattering

    NASA Astrophysics Data System (ADS)

    Freney, Evelyn J.; Adachi, Kouji; Buseck, Peter R.

    2010-10-01

    Internally mixed aerosol particles consisting of one or more hygroscopic compounds can contain both solid and liquid parts, the details depending on the relative humidity (RH). The solid-to-liquid transition of such particles as the RH increases influences their light-scattering properties through changes in particle shape, size, and refractive index. Most techniques used to analyze ambient aerosol particles do not have the ability to view both solid and liquid phases within individual particles. Using a transmission electron microscope fitted with an environmental cell (ETEM), we analyzed laboratory-prepared and ambient aerosol samples. Our results suggest that solid inclusions inside aqueous droplets at high RH values (e.g., >65%) are likely to be common in atmospheric particles. In order to assess the effects of such inclusions, we calculated their combined light-scattering efficiencies using a discrete dipole approximation (DDA). The results show differences compared to those from a core-shell model, with an average increase in light scattering of ˜20%. The results demonstrate that the combination of ETEM measurements of ambient particles with DDA calculations yields new insights into the effects of inclusions on the light-scattering properties of internally mixed particles.

  1. Morphology and mixing state of atmospheric particles: Links to optical properties and cloud processing

    NASA Astrophysics Data System (ADS)

    China, Swarup

    Atmospheric particles are ubiquitous in Earth's atmosphere and impact the environment and the climate while affecting human health and Earth's radiation balance, and degrading visibility. Atmospheric particles directly affect our planet's radiation budget by scattering and absorbing solar radiation, and indirectly by interacting with clouds. Single particle morphology (shape, size and internal structure) and mixing state (coating by organic and inorganic material) can significantly influence the particle optical properties as well as various microphysical processes, involving cloud-particle interactions and including heterogeneous ice nucleation and water uptake. Conversely, aerosol cloud processing can affect the morphology and mixing of the particles. For example, fresh soot has typically an open fractal-like structure, but aging and cloud processing can restructure soot into more compacted shapes, with different optical and ice nucleation properties. During my graduate research, I used an array of electron microscopy and image analysis tools to study morphology and mixing state of a large number of individual particles collected during several field and laboratory studies. To this end, I investigated various types of particles such as tar balls (spherical carbonaceous particles emitted during biomass burning) and dust particles, but with a special emphasis on soot particles. In addition, I used the Stony Brook ice nucleation cell facility to investigate heterogeneous ice nucleation and water uptake by long-range transported particles collected at the Pico Mountain Observatory, in the Archipelago of the Azores. Finally, I used ice nucleation data from the SAAS (Soot Aerosol Aging Study) chamber study at the Pacific Northwest National Laboratory to understand the effects that ice nucleation and supercooled water processing has on the morphology of residual soot particles. Some highlights of our findings and implications are discussed next. We found that the morphology of fresh soot emitted by vehicles depends on the driving conditions (i.e.; the vehicle specific power). Soot emitted by biomass burning is often heavily coated by other materials while processing of soot in urban environment exhibits complex mixing. We also found that long-range transported soot over the ocean after atmospheric processing is very compacted. In addition, our results suggest that freezing process can facilitate restructuring of soot and results into collapsed soot. Furthermore, numerical simulations showed strong influence on optical properties when fresh open fractal-like soot evolved to collapsed soot. Further investigation of long-range transported aged particles exhibits that they are efficient in water uptake and can induce ice nucleation in colder temperature. Our results have implications for assessing the impact of the morphology and mixing state of soot particles on human health, environment and climate. Our findings can provide guidance to numerical models such as particle-resolved mixing state models to account for, and better understand, vehicular emissions and soot evolution since its emission to atmospheric processing in urban environment and finally in remote regions after long-range transport. Morphology and mixing state information can be used to model observational-constrained optical properties. The details of morphology and mixing state of soot particles are crucial to assess the accuracy of climate models in describing the contribution of soot radiative forcing and their direct and indirect climate effects. Finally, our observations of ice nucleation ability by aged particles show that nucleated particles are internally mixed and coated with several materials.

  2. Gas–particle partitioning of organic compounds in the atmosphere

    Microsoft Academic Search

    Mihalis Lazaridis

    1999-01-01

    Gas–particle partitioning of condensable organic compounds in the atmosphere is described using two methods. The first method is based on the use of a comprehensive mechanistic model of adsorption\\/absorption processes. The second method is based on aerosol yields estimates. The model parameters in the adsorption\\/absorption model are evaluated from experimental data. The concepts of concentration of adsorbed molecules on the

  3. RHESSI OBSERVATION OF ATMOSPHERIC GAMMA RAYS FROM IMPACT OF SOLAR ENERGETIC PARTICLES ON 21 APRIL 2002

    E-print Network

    California at Berkeley, University of

    RHESSI OBSERVATION OF ATMOSPHERIC GAMMA RAYS FROM IMPACT OF SOLAR ENERGETIC PARTICLES ON 21 APRIL by the Earth's atmosphere during impact of solar energetic particles in the south polar region from 16 to estimate the spectrum of solar energetic particles that impacted the atmosphere. The 21 April spectrum

  4. Material flammability in space exploration atmospheres

    Microsoft Academic Search

    Sara Suzanne McAllister

    2008-01-01

    In order to reduce the risk of decompression sickness associated with extravehicular activity, NASA is designing the next generation of exploration vehicles with a different cabin pressure and oxygen concentration than used previously. This work explores how the flammability of solid materials changes in this new environment. One method to evaluate material flammability is by its ease of ignition. To

  5. Wood-based building materials and atmospheric carbon emissions

    Microsoft Academic Search

    Andrew H Buchanan; S. Bry Levine

    1999-01-01

    This study investigates the global impact of wood as a building material by considering emissions of carbon dioxide to the atmosphere. Wood is compared with other materials in terms of stored carbon and emissions of carbon dioxide from fossil fuel energy used in manufacturing. An analysis of typical forms of building construction shows that wood buildings require much lower process

  6. Study of inlet materials for sampling atmospheric nitric acid

    Microsoft Academic Search

    J. A. Neuman; L. G. Huey; T. B. Ryerson; D. W. Fahey

    1999-01-01

    The adsorption of nitric acid (HNOâ) from a flowing gas stream is studied for a variety of wall materials to determine their suitability for use in atmospheric sampling instruments. Parts per billion level mixtures of HNOâ in synthetic air flow through tubes of different materials such that >80% of the molecules interact with the walls. A chemical ionization mass spectrometer

  7. Impacts of solar particle events on middle atmospheric chlorine compounds

    NASA Astrophysics Data System (ADS)

    Winkler, Holger; Sinnhuber, Miriam; Wissing, Jan-Maik; Kallenrode, May-Britt; Stiller, Gabrielle; von Clarmann, Thomas; Funke, Bernd

    2010-05-01

    Solar particle events (SPEs) are well known sources of chemical perturbations in the middle atmosphere. A well-understood effect is the release of reactive NOx and HOx, and the subsequent destruction of ozone. Satellite measurements (HALOE, MIPAS, AURA-MLS) have shown that there is also chlorine activation in the stratosphere and mesosphere, and an increase of chlorine nitrate in the lower and middle stratosphere during SPEs. This cannot be explained by the NOx and HOx increase alone. Atmospheric models with standard parametrizations of NOx and HOx production due to SPEs fail to reproduce the magnitude of the observed chlorine disturbances. Numerical simulations using the University of Bremen ion chemistry (UBIC) model show a much better agreement with measurements if full negative ion chemistry is considered additionally to the NOx and HOx production. The UBIC results in combination with atmospheric models indicate that reactions of negative cluster ions can have a significant impact on the middle atmosphere's chlorine chemistry during SPEs. There is a transformation of HCl into active chlorine via anion cluster chemistry. Additionally, the release of O(1D) through N(2D) + O2 - NO + O(1D) has a considerable impact on chlorine species. Results of UBIC simulations for different SPEs (July 2000, October 2003, January 2005) are presented. They are compared with the observed changes of chlorine compounds - HCl, HOCl, ClO and ClONO2 - from the satellite instruments HALOE, MIPAS and AURA-MLS.

  8. Particle impact damping: influence of material and size 

    E-print Network

    Marhadi, Kun Saptohartyadi

    2005-02-17

    In this study, particle impact damping is measured for a cantilever beam with a particle-filled enclosure attached to its free end. Many particle materials are tested: lead spheres, steel spheres, glass spheres, tungsten carbide pellets, lead dust...

  9. Laboratory Studies of Hydrocarbon Nucleation on Tholin Particles and Thin Organic Films: Application to Titan's Atmosphere

    NASA Technical Reports Server (NTRS)

    Curtis, Daniel B.; Glandorf, David L.; Toon, Owen B.; Tolbert, Margaret A.; McKay, Christopher P.; Khare, Bishun N.

    2001-01-01

    Titan, Saturn's largest satellite, has a thick nitrogen/methane atmosphere. In Titan's lower atmosphere, methane is saturated or supersaturated with respect to nucleation and may form clouds. To better characterize the properties of Titan's methane clouds we have measured the saturation ratio required to obtain butane nucleation, S (sub crit), on Titan tholin material and organic films. We find a critical saturation ratio for butane on tholin particles of S (sub crit) = 1.40, suggesting high supersaturations are required for nucleation. If methane is similar to butane, we expect high supersaturations of methane as well. This could favor the formation of a small number of large particles, consistent with recent measurements of methane rain on Titan.

  10. Ignition of a Combustible Atmosphere by Incandescent Carbon Wear Particles

    NASA Technical Reports Server (NTRS)

    Buckley, Donald H.; Swikert, Max A.; Johnson, Robert L.

    1960-01-01

    A study was made to determine whether carbon wear particles from carbon elements in sliding contact with a metal surface were sufficiently hot to cause ignition of a combustible atmosphere. In some machinery, electric potential differences and currents may appear at the carbon-metal interface. For this reason the effect of these voltages and currents on the ability of carbon wear particles to cause ignition was evaluated. The test specimens used in the investigation were carbon vanes taken from a fuel pump and flat 21-inch-diameter 2 metal disks (440-C stainless steel) representing the pump housing. During each experiment a vane was loaded against a disk with a 0.5-pound force, and the disk was rotated to give a surface speed of 3140 feet per minute. The chamber of the apparatus that housed the vane and the disk was filled with a combustible mixture of air and propane. Various voltages and amperages were applied across the vane-disk interface. Experiments were conducted at temperatures of 75, 350, 400, and 450 F. Fires were produced by incandescent carbon wear particles obtained at conditions of electric potential as low as 106 volts and 0.3 ampere at 400 F. Ignitions were obtained only with carbon wear particles produced with an electric potential across the carbon-vane-disk interface. No ignitions were obtained with carbon wear particles produced in the absence of this potential; also, the potential difference produced no ignitions in the absence of carbon wear particles. A film supplement showing ignition by incandescent wear particles is available.

  11. Small particle cirrus observed by the Atmospheric Infrared Sounder

    NASA Astrophysics Data System (ADS)

    Kahn, B. H.; Eldering, A.; Fishbein, E. F.

    2003-04-01

    The high-resolution spectra of the Atmospheric Infrared Sounder (AIRS) have provided an opportunity to globally observe small particle-dominated cirrus clouds. The shape of the radiance spectra in the atmospheric windows is uniquely influenced by small ice crystals with an effective radius (reff) of a few 10s of microns and smaller. In some rare instances, minima in the AIRS brightness temperature (BT) spectra between 800 to 850 cm-1 are seen, consistent with the existence of ice particles with an reff smaller than 3 microns. Much more frequent occurences of small ice particle clouds with reff larger than 3 microns are observed through the large 998 to 811 cm-1 BT differences without minima. The small particle events are occasionally found in orographic cirrus clouds, in and around cumulonimbus towers, and in cirrus bands far removed from convection and orography. Several cases spanning the variety of small particle-dominated cirrus events will be presented. AIRS, located on the EOS-Aqua platform, is a high-resolution grating spectrometer that scans at angles 49.5 degrees on either side of nadir view, at both visible and infrared wavelengths. The surface footprint is 13.5 km at the nadir view, and coverage in the infrared is in three bandpasses (649-1136, 1265-1629, and 2169-2674 cm-1). Comparisons of observed spectra are made with simulated spectra generated by a plane-parallel scattering radiative transfer model using ice particle shapes and sizes calculated by the T-matrix method. These comparisons yield information on small particle cirrus cloud reff and optical depth. Aumann, H.H., and R.J. Pagano, Atmospheric Infrared Sounder on the Earth Observing System. Opt. Eng. 33, 776-784, 1994. Mishchenko, M.I., and L.D. Travis, Capabilities and limitations of a current Fortran implementation of the T-matrix method for randomly oriented, rotationally symmetric scatterers. J. Quant. Spectrosc. Radiat. Transfer, 60, 309-324, 1998. Moncet, J.L., and S.A. Clough, Accelerated monochromatic radiative transfer for scattering atmospheres: Application of a new model to spectral radiance observations. J. Geophys. Res., 102, 21,853-21,866, 1997. Rathke, C., and J. Fischer, Retrieval of cloud microphysical properties from thermal infrared observations by a fast iterative radiance fitting method, J. Atmos. Ocean. Tech., 17, 1509-1524, 2000. Smith, W.L., S. Ackerman, H. Revercomb, H. Huang, D.H. DeSlover, W. Feltz, L. Gumley, and A. Collard, Infrared spectral absorption of nearly invisible cirrus clouds. Geophys. Res. Lett., 25, 1137-1140, 1998. Strabala, K.I., S.A. Ackerman, and W.P. Menzel, Cloud properties inferred from 8-12 micron data. J. Appl. Meteor., 33, 212-229, 1994.

  12. Chemical composition of particles in the black sea atmosphere

    NASA Astrophysics Data System (ADS)

    Hacisalihoglu, G.; Eliyakut, F.; Olmez, I.; Balkas, T. I.; Tuncel, G.

    Shipborne samples collected from the Black Sea atmosphere were analysed by instrumental neutron activation analysis, atomic absorption spectrometry and ion chromatography for approximately 40 elements and ions. Concentrations of most of the elements are found to be a factor of two higher in the western part of the Black Sea than corresponding concentrations in the eastern part. Main source regions for anthropogenic elements were in Europe. The WNW, WSW and SSW sectors together account for 70% of observed concentrations of elements. Principal component analysis showed a crustal, a marine and three anthropogenic factors. Two of the anthropogenic factors were the result of long-range transport of particles and the third indicated a local iron and steel industry. Atmospheric fluxes of elements to the Black Sea were calculated using observed concentrations, scavenging ratios and precipitation data and results were compared with riverine fluxes of elements. For crustal elements, riverine fluxes were found to be dominant, but for pollution-derived elements, atmospheric fluxes were comparable to riverine fluxes to the Black Sea.

  13. Energetic particle energy deposition in Titan's upper atmosphere

    NASA Astrophysics Data System (ADS)

    Westlake, J. H.; Smith, H. T.; Mitchell, D. G.; Paranicas, C. P.; Rymer, A. M.; Bell, J. M.; Waite, J. H., Jr.; Mandt, K. E.

    2012-04-01

    Titan’s upper atmosphere has been observed to be variable on a pass-by-pass basis. During the nominal mission where the Cassini Ion and Neutral Mass Spectrometer (INMS) only sampled the northern hemisphere this variability was initially believed to be tied to solar drivers manifest in latitudinal variations in the thermal structure of the upper atmosphere. However, when Cassini delved into the southern hemisphere the latitudinal dependence was not present in the data. Recently, Westlake et al. (2011) showed that the pass-by-pass variability is correlated with the deviations in the plasma environment as identified by Rymer et al. (2009) and Simon et al. (2010). Furthermore, the studies of Westlake et al. (2011) and Bell et al. (2011) showed that Titan’s upper atmosphere responds to changes in the ambient magnetospheric plasma on timescales of roughly one Titan day (16 Earth days). We report on recent studies of energy deposition in Titan’s upper atmosphere. Previous studies by Smith et al. (2009), Cravens et al. (2008), Tseng et al. (2008), and Shah et al. (2009) reported on energetic proton and oxygen ion precipitation. Back of the envelope calculations by Sittler et al. (2009) showed that magnetospheric energy inputs are expected to be of the order of or greater than the solar processes. We report on further analysis of the plasma environment around Titan during the flybys that the INMS has good data. We utilize data from the Magnetospheric Imaging Instrument to determine how the magnetospheric particle population varies from pass to pass and how this influences the net magnetospheric energy input prior to the flyby. We also report on enhanced energetic neutral atom emissions during select highly energetic passes. References: Bell, J., et al.: “Simulating the time-dependent response of Titan's upper atmosphere to periods of magnetospheric forcing”. Geophys. Res. Lett., Vol. 38, L06202, 2011. Rymer, A. M., et al.: “Discrete classification and electron energy spectra of Titan’s varied magnetospheric environment”. Geophys. Res. Lett., Vol. 36, L15109, 2009. Simon, S., et al.: “Titan’s highly dynamic magnetic environment: A systematic survey of Cassini magnetometer observations from flybys TA-T62”. Planet. Space. Sci., Vol 58, pp. 1230-1251, 2010. Sittler, E., et al.: “Energy deposition processes in Titan’s upper atmosphere and its induced magnetosphere”. In Titan from Cassini-Huygens. 2009. Tseng, W.-L, et al.: “Exospheric heating by pickup ions at Titan”. Adv. Space Res. Vol 42. Pp 54-60, 2008. Westlake, J. H., et al.: “Titan’s thermospheric response to various plasma environments”. J. Geophys. Res., Vol. 116, A03

  14. Atmospheric dc glow discharge using liquid anode for production of nano-particle

    NASA Astrophysics Data System (ADS)

    Shirai, Naoki; Uchida, Satoshi; Tochikubo, Fumiyoshi; Tokyo Metoropolitan University Team

    2011-10-01

    Non-thermal plasma in and with liquids has attracted considerable interest for its potential use in a wide range of applications. In particular, the use of a discharge with a liquid as an electrode for material processes has been reported. In this study, we focused on atmospheric glow discharge using liquid as anode, and the production of nano-particle by the atmospheric plasma reduction of aqueous cations. When atmospheric dc glow discharge with helium flow was generated, self-organized anode patterns were observed on the liquid. The pattern formation depends on the current, gap length and helium flow rate. With increasing discharge current or gap length, anode luminous spot changed to self-organized patterns. Anode pattern formation depends on the liquid conductivity. When AgNO3 solution is used as liquid anode of the discharge, the liquid changed dark color near the plasma-liquid interface. We confirm the dark region including nano-particle which diameter is about 5-50 nm by TEM observation. The liquid anode discharge reduction of aqueous cations is specific and different from typical electrolysis. The diameter of nano-particle is changed by current, discharge time and addition of surface-active agent to liquid.

  15. Water and acid soluble trace metals in atmospheric particles

    NASA Technical Reports Server (NTRS)

    Lindberg, S. E.; Harriss, R. C.

    1983-01-01

    Continental aerosols are collected above a deciduous forest in eastern Tennessee and subjected to selective extractions to determine the water-soluble and acid-leachable concentrations of Cd, Mn, Pb, and Zn. The combined contributions of these metals to the total aerosol mass is 0.5 percent, with approximately 70 percent of this attributable to Pb alone. A substantial fraction (approximately 50 percent or more) of the acid-leachable metals is soluble in distilled water. In general, this water-soluble fraction increases with decreasing particle size and with increasing frequency of atmospheric water vapor saturation during the sampling period. The pattern of relative solubilities (Zn being greater than Mn, which is approximately equal to Cd, which is greater than Pb) is found to be similar to the general order of the thermodynamic solubilities of the most probable salts of these elements in continental aerosols with mixed fossil fuel and soil sources.

  16. Dielectric-Particle Injector For Processing Of Materials

    NASA Technical Reports Server (NTRS)

    Leung, Philip L.; Gabriel, Stephen B.

    1992-01-01

    Device generates electrically charged particles of solid, or droplets of liquid, fabricated from dielectric material and projects them electrostatically, possibly injecting them into electrostatic-levitation chamber for containerless processing. Dielectric-particle or -droplet injector charges dielectric particles or droplets on zinc plate with photo-electrons generated by ultraviolet illumination, then ejects charged particles or droplets electrostatically from plate.

  17. Seasonal differences of the atmospheric particle size distribution in a metropolitan area in Japan.

    PubMed

    Fujitani, Yuji; Kumar, Prashant; Tamura, Kenji; Fushimi, Akihiro; Hasegawa, Shuich; Takahashi, Katsuyuki; Tanabe, Kiyoshi; Kobayashi, Shinji; Hirano, Seishiro

    2012-10-15

    We compared the effect of ambient temperature observed in two different seasons on the size distribution and particle number concentration (PNC) as a function of distance (up to ~250 m) from a major traffic road (25% of the vehicles are heavy-duty diesel vehicles). The modal particle diameter was found between 10 and 30 nm at the roadside in the winter. However, there was no peak for this size range in the summer, even at the roadside. Ambient temperature affects both the atmospheric dilution ratio (DR) and the evaporation rate of particles, thus it affects the decay rate of PNC. We corrected the DR effect in order to focus on the effect of particle evaporation on PNC decay. The decay rate of PNC with DR was found to depend on the season and particle diameter. During the winter, the decay rate for smaller particles (<30 nm) was much higher (i.e., the concentration decreased significantly against DR), whereas it was low during the summer. In contrast, for particles >30 nm in diameter, the decay rate was nearly the same during both seasons. This distinction between particles less than or greater than 30 nm in diameter reflects differences in particle volatility properties. Mass-transfer theory was used to estimate evaporation rates of C20-C36 n-alkane particles, which are the major n-alkanes in diesel exhaust particles. The C20-C28 n-alkanes of 30-nm particles completely evaporate at 31.2 °C (summer), and their lifetime is shorter than the transport time of air masses in our region of interest. Absence of the peak at 10-30 nm and the low decay rate of PNC <30 nm in diameter in the summer were likely due to the evaporation of compounds of similar volatilities comparable to the C20-C36 n-alkanes from particles near the exhaust pipes of vehicles, and complete evaporation of semivolatile materials before they reached the roadside. These results suggest that the lifetime of particles <30 nm in diameter depends on the ambient temperature, which differs between seasons. This leads us to conclude that these particles show distinctly different spatial distributions depending on the season. PMID:22960110

  18. Use of Atmospheric Glow Discharge Plasma to Modify Spaceport Materials

    NASA Technical Reports Server (NTRS)

    Trigwell, S.; Shuerger, A. C.; Buhler, C. R.; Calle, C. J.

    2006-01-01

    Numerous materials used in spaceport operations require stringent evaluation before they can be utilized. It is critical for insulative polymeric materials that any surface charge be dissipated as rapidly as possible to avoid Electrostatic Discharges (ESD) that could present a danger. All materials must pass the Kennedy Space Center (KSC) standard electrostatic test [1]; however several materials that are considered favorable for Space Shuttle and International Space Station use have failed. Moreover, to minimize contamination of Mars spacecraft, spacecraft are assembled under cleanroom conditions and specific cleaning and sterilizing procedures are required for all materials. However, surface characteristics of these materials may allow microbes to survive by protecting them from sterilization and cleaning techniques. In this study, an Atmospheric Pressure Glow Discharge Plasma (APGD) [2] was used to modify the surface of several materials. This allowed the materials surface to be modified in terms of hydrophilicity, roughness, and conductivity without affecting the bulk properties. The objectives of this study were to alter the surface properties of polymers for improved electrostatic dissipation characteristics, and to determine whether the consequent surface modification on spaceport materials enhanced or diminished microbial survival.

  19. Graphene: from materials science to particle physics

    E-print Network

    Joaquín E. Drut; Timo A. Lähde; Eero Tölö

    2010-11-02

    Since its discovery in 2004, graphene, a two-dimensional hexagonal carbon allotrope, has generated great interest and spurred research activity from materials science to particle physics and vice versa. In particular, graphene has been found to exhibit outstanding electronic and mechanical properties, as well as an unusual low-energy spectrum of Dirac quasiparticles giving rise to a fractional quantum Hall effect when freely suspended and immersed in a magnetic field. One of the most intriguing puzzles of graphene involves the low-temperature conductivity at zero density, a central issue in the design of graphene-based nanoelectronic components. While suspended graphene experiments have shown a trend reminiscent of semiconductors, with rising resistivity at low temperatures, most theories predict a constant or even decreasing resistivity. However, lattice field theory calculations have revealed that suspended graphene is at or near the critical coupling for excitonic gap formation due to strong Coulomb interactions, which suggests a simple and straightforward explanation for the experimental data. In this contribution we review the current status of the field with emphasis on the issue of gap formation, and outline recent progress and future points of contact between condensed matter physics and Lattice QCD.

  20. Spatially resolved chemical imaging of individual atmospheric particles using nanoscale imaging mass spectrometry: Insights into particle origin and chemistry

    NASA Astrophysics Data System (ADS)

    Ghosal, S.; Weber, P. K.; Laskin, A.

    2014-12-01

    Knowledge of the spatially-resolved composition of atmospheric particles is essential for differentiating between their surface versus bulk chemistry, understanding particle reactivity and the potential environmental impact. We demonstrate the application of nanometer-scale secondary ion mass spectrometry (Cameca NanoSIMS 50 ion probe) for 3D chemical imaging of individual atmospheric particles without any sample pre-treatment, such as the sectioning of particles. Use of NanoSIMS depth profile analysis enables elemental mapping of particles with nanometer spatial resolution over a broad of range of particle sizes. We have used this technique to probe spatially resolved composition of ambient particles collected during a field campaign in Mexico City. Particles collected during this campaign have been extensively characterized in the past using other particle analysis techniques and hence offer a unique opportunity for exploring the utility of depth resolved chemical imaging in ambient particle research. Particles examined in this study include those collected during a pollution episode related to urban waste incineration as well as background particles from the same location prior to the episode. Particles from the pollution episode show substantial intra-particle compositional variability typical of particles resulting from multiple emission sources. In contrast, the background particles have relatively homogeneous compositions with enhanced presence of nitrogen, oxygen and chlorine at the particle surface. The observed surface enhancement of nitrogen and oxygen species is consistent with the presence of surface nitrates resulting from gas-particle heterogeneous interactions and is indicative of atmospheric ageing of the particles. The results presented here illustrate 3D characterization of ambient particles for insights into their chemical history.

  1. Quantifying the kinetic limitations of atmospheric gas-to-particle conversion

    NASA Astrophysics Data System (ADS)

    Booth, A.; Murphy, B.; Riipinen, I.; Percival, C.; Topping, D. O.

    2013-12-01

    Atmospheric aerosol particles, from anthropogenic and biogenic sources, remain a major uncertainty in the Earth system: they impact the climate by directly scattering and absorbing solar radiation, as well as regulating the properties of clouds. On regional scales, aerosols are among the main pollutants deteriorating air quality, their impacts on both poorly quantified. Reducing these uncertainties requires accurate knowledge on the composition, concentrations and size distributions of these particles as they reside in the atmosphere. Unfortunately, there are currently huge uncertainties in many fundamental parameters that are required to predict their environmental impacts. This is largely down to the fact that a significant fraction of atmospheric aerosol particles are comprised of organic material (20-90% of particle mass), containing potentially thousands of compounds with largely uncertain properties It is becoming increasingly evident that aerosols exist as metastable amorphous states, rather than simple liquid/solid mixtures. Empirical evidence suggests that particles can form glass like substances. As the glass transition temperature is approached, an increase in viscosity leads to a reduced rate of molecular diffusion and an arrested non-equilibrium structure. Partitioning between the gas and condensed phase is kinetically limited in such amorphous states. Traditional organic aerosol models do not account for this, they assume that 1) the aerosol phase is a well-mixed non-viscous liquid; 2) the aerosol phase instantaneously equilibrates with the gas phase constituents. This adds significant uncertainty to predictions of gas/particle mass transfer as mixing timescales are ultimately governed by the diffusion coefficients of the aerosol constituents in the aerosol, which, on the other hand, are connected to the viscosity of the particulate matter. For typical aerosol sizes, the characteristic time for mixing could increase from a few milliseconds to hours or even days. In this study, we present direct laboratory determination of viscosity/diffusing of atmospherically relevant species along with an evaluation of composition dependent predictive techniques. Output from highly detailed chemical mechanisms are used to probe potential sensitivities of these kinetic limitations and sensitivities to our predictive capability.

  2. Particle deposition and clearance of atmospheric particles in the human respiratory tract during LACE 98

    NASA Astrophysics Data System (ADS)

    Bundke, U.; Hänel, G.

    2003-04-01

    During the LACE 98footnote{Lindenberg Aerosol Characterization Experiment, (Germany) 1998} experiment microphysical, chemical and optical properties of atmospheric particles were measured by several groups. (Bundke et al.). The particle deposition and clearance of the particles in the human respiratory tract was calculated using the ICRP (International Commission on Radiological Protection) deposition and clearance model (ICRP 1994). Particle growth as function of relative humidity outside the body was calculated from measurement data using the model introduced by Bundke et al.. Particle growth inside the body was added using a non-equilibrium particle growth model. As a result of the calculations, time series of the total dry particle mass and -size distribution were obtained for all compartments of the human respiratory tract defined by ICRP 1994. The combined ICRP deposition and clearance model was initialized for different probationers like man, woman, children of different ages and several circumstances like light work, sitting, sleeping etc. Keeping the conditions observed during LACE 98 constant a approximation of the aerosol burdens of the different compartments was calculated up to 4 years of exposure and compared to the results from Snipes et al. for the "Phoenix" and "Philadelphia" aerosol. References: footnotesize{ Bundke, U. et al.,it{Aerosol Optical Properties during the Lindenberg Aerosol Characterization Experiment (LACE 98)} ,10.1029/2000JD000188, JGR, 2002 ICRP,it{Human Respiratory Tract Model for Radiological Protection, Bd. ICRP Publication 66}, Annals of the ICRP, 24,1-3, Elsevier Science, Ocford, 1994 Snipes et al. ,it{The 1994 ICRP66 Human Respiratory Tract Model as a Tool for predicting Lung Burdens from Exposure to Environmental Aerosols}, Appl. Occup. Environ. Hyg., 12, 547-553,1997}

  3. Effects of atmospheric particles from Southern California on the optical properties of seawater

    Microsoft Academic Search

    Malgorzata Stramska; Dariusz Stramski; Marta Cichocka; Agnieszka Cieplak; S?awomir B. Wo?niak

    2008-01-01

    The role of particles deposited from the atmosphere to the ocean is poorly understood in ocean optics. We examined the light absorption and scattering properties of atmospheric particulate matter, which was collected by dry deposition near the Pacific coastline in La Jolla, Southern California, and then suspended in particle-free seawater for subsequent laboratory measurements. Within these suspensions, we measured the

  4. Particle production in the remote marine atmosphere: Cloud outflow and subsidence during ACE 1

    Microsoft Academic Search

    A. D. Clarke; J. L. Varner; F. Eisele; R. L. Mauldin; D. Tanner; M. Litchy

    1998-01-01

    During November and December 1995 the First Aerosol Characterization Experiment (ACE 1) was undertaken as part of the International Global Atmospheric Chemistry (IGAC) Program. A key objective of the aircraft component of this experiment included the identification of source regions for new particles in the remote marine atmosphere. No evidence was found for particle production in the marine boundary layer

  5. Multiscale Modeling of Metallic Materials Containing Embedded Particles

    NASA Technical Reports Server (NTRS)

    Phillips, Dawn R.; Iesulauro, Erin; Glaessgen, Edward H.

    2004-01-01

    Multiscale modeling at small length scales (10(exp -9) to 10(exp -3) m) is discussed for aluminum matrices with embedded particles. A configuration containing one particle surrounded by about 50 grains and subjected to uniform tension and lateral constraint is considered. The analyses are performed to better understand the effects of material configuration on the initiation and progression of debonding of the particles from the surrounding aluminum matrix. Configurational parameters considered include particle aspect ratio and orientation within the surrounding matrix. Both configurational parameters are shown to have a significant effect on the behavior of the materials as a whole. For elliptical particles with the major axis perpendicular to the direction of loading, a particle with a 1:1 aspect ratio completely debonds from the surrounding matrix at higher loads than particles with higher aspect ratios. As the particle major axis is aligned with the direction of the applied load, increasing amounts of load are required to completely debond the particles.

  6. Magnetic orientation of fine particles in composite materials

    Microsoft Academic Search

    D. M. Karpinos; G. I. Yaglo; L. M. Aplninskaya; N. F. Efremova; Yu. A. Maksimenko

    1982-01-01

    This difficulty can be overcome by coating such particles or fibers with a ferromagnetic material. The aim here must be to apply uniform coatings enabling particles and fibers to Orient themselves in comparatively weak magnetic fields without at the same time affecting any of the properties of the starting material. In this connection, the work described in this paper was

  7. The Impact of Energetic Particle Precipitation on the Earths Atmosphere

    NASA Astrophysics Data System (ADS)

    Funke, B.; López-Puertas, M.; García-Comas, M.; Bermejo-Pantaleón, D.; Stiller, G. P.; von Clarmann, T.

    Energetic particle precipitation (EPP) represents an important Sun-Earth coupling mechanism with important implications on polar stratospheric ozone chemistry. Solar protons generated during solar storms cause sporadically in situ production of stratospheric NO x and HO x radicals involved in catalytic ozone destruction. Further, NO produced continuously in the mesosphere and lower thermosphere by medium energy electron precipitation (EEP) descends to the stratosphere during the polar winter, where it represents an additional, though variable source of NO x . The capability of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) to measure all important NO y species, as well as ClO and HOCl with global coverage including the polar night regions make it an ideal instrument for studying EPP effects on stratospheric chemistry. We present a quantitative assessment of EPP-induced composition changes as observed by MIPAS during 2002-2004, including the unusually strong solar proton event in October/November 2003. The impact of EPP on the stratospheric ozone budget has been studied with chemical models. The stratospheric ozone loss in the polar regions reached 18DU and lasted over months to years.

  8. Size matters in the water uptake and hygroscopic growth of atmospherically relevant multicomponent aerosol particles.

    PubMed

    Laskina, Olga; Morris, Holly S; Grandquist, Joshua R; Qin, Zhen; Stone, Elizabeth A; Tivanski, Alexei V; Grassian, Vicki H

    2015-05-14

    Understanding the interactions of water with atmospheric aerosols is crucial for determining the size, physical state, reactivity, and climate impacts of this important component of the Earth's atmosphere. Here we show that water uptake and hygroscopic growth of multicomponent, atmospherically relevant particles can be size dependent when comparing 100 nm versus ca. 6 ?m sized particles. It was determined that particles composed of ammonium sulfate with succinic acid and of a mixture of chlorides typical of the marine environment show size-dependent hygroscopic behavior. Microscopic analysis of the distribution of components within the aerosol particles show that the size dependence is due to differences in the mixing state, that is, whether particles are homogeneously mixed or phase separated, for different sized particles. This morphology-dependent hygroscopicity has consequences for heterogeneous atmospheric chemistry as well as aerosol interactions with electromagnetic radiation and clouds. PMID:25521409

  9. Chemical Bonding and Structural Information of Black CarbonReference Materials and Individual Carbonaceous AtmosphericAerosols

    SciTech Connect

    Hopkins, Rebecca J.; Tivanski, Alexei V.; Marten, Bryan D.; Gilles, Mary K.

    2007-04-25

    The carbon-to-oxygen ratios and graphitic nature of a rangeof black carbon standard reference materials (BC SRMs), high molecularmass humic-like substances (HULIS) and atmospheric particles are examinedusing scanning transmission X-ray microscopy (STXM) coupled with nearedge X-ray absorption fine structure (NEXAFS) spectroscopy. UsingSTXM/NEXAFS, individual particles with diameter>100 nm are studied,thus the diversity of atmospheric particles collected during a variety offield missions is assessed. Applying a semi-quantitative peak fittingmethod to the NEXAFS spectra enables a comparison of BC SRMs and HULIS toparticles originating from anthropogenic combustion and biomass burns,thus allowing determination of the suitability of these materials forrepresenting atmospheric particles. Anthropogenic combustion and biomassburn particles can be distinguished from one another using both chemicalbonding and structural ordering information. While anthropogeniccombustion particles are characterized by a high proportion ofaromatic-C, the presence of benzoquinone and are highly structurallyordered, biomass burn particles exhibit lower structural ordering, asmaller proportion of aromatic-C and contain a much higher proportion ofoxygenated functional groups.

  10. Particle-based simulation of granular materials

    Microsoft Academic Search

    Nathan Bell; Yizhou Yu; Peter J. Mucha

    2005-01-01

    Granular materials, such as sand and grains, are ubiquitous. Simulating the 3D dynamic motion of such materials represents a challenging problem in graphics because of their unique physical properties. In this paper we present a simple and effective method for granular material simulation. By incorporating techniques from physical models, our approach describes granular phenomena more faithfully than previous methods. Granular

  11. HUMIDITY EFFECTS ON THERMAL ATMOSPHERIC TRANSMISSIONS: STUDY OF POTENTIAL EFFECTS OF SMALL HYGROSCOPIC AEROSOL PARTICLES IN THE

    E-print Network

    Salvaggio, Carl

    HUMIDITY EFFECTS ON THERMAL ATMOSPHERIC TRANSMISSIONS: STUDY OF POTENTIAL EFFECTS OF SMALL region. This atmospheric anomaly has been linked to conditions of high environmental humidity of humidity, temperature, particle size distribution, and number density of aerosol particle stream

  12. Reducing particle adhesion by material surface engineering

    NASA Astrophysics Data System (ADS)

    Crowder, Mark S.; Stover, Robert; Lawitzke, Anna; Devaud, Genevieve; Dove, Adrienne; Wang, Xu

    2010-08-01

    We have developed surface chemical modification processes which when applied to a variety of surfaces renders the surfaces resistant to particulate contamination. Chemically modified surfaces are shown to shed particles at a dramatically higher level as compared to native surfaces. This is demonstrated on a variety of surfaces that include optics, polymers, metals and silicon. The adhesive force between lunar stimulant particles (JSC-1AF) and black Kapton is measured to decrease by 95% when the black Kapton surface is chemically modified. The chemical modification process is demonstrated to not change the surface roughness of a smooth silicon wafer while decreasing particle affinity. The optical properties of chemically modified surfaces are reported. The surface modification process is robust and stable to aggressive cleaning. The particle shedding properties of chemically modified surfaces are retained after simulated extraterrestrial vacuum ultra-violet light exposure and temperature excursions to 140°C. This technology has the potential to provide a robust passive particle mitigation solution for optics, mechanical systems and particle sensitive applications.

  13. Atmospheric particle number size distribution in central Europe: Statistical relations to air masses and meteorology

    Microsoft Academic Search

    Wolfram Birmili; Alfred Wiedensohler; Jost Heintzenberg; Katrin Lehmann

    2001-01-01

    Atmospheric particle number size distributions determined over 1.5 years at a central European site were statistically analyzed in terms of their relation to time of day, season, meteorology, and synoptic-scale air masses. All size distributions were decomposed into lognormal particle modes corresponding to the accumulation, Aitken, aged nucleation, and nucleation modes. The concentration of nucleation mode particles (30 nm) lacked

  14. Efficient Collection of Atmospheric Aerosols with a Particle Concentrator—Electrostatic Precipitator Sampler

    Microsoft Academic Search

    Bangwoo Han; Neelakshi Hudda; Zhi Ning; Yong-Jin Kim; Constantinos Sioutas

    2009-01-01

    A novel particle sampling methodology developed recently by our group (Han et al. 2008) has been extended in this article to collect atmospheric particles in electrostatic precipitators (ESPs) for chemical and biological–toxicological analysis. Particles are grown to super-micron droplets via condensation of ultrapure deionized water, and concentrated by virtual impaction in the versatile aerosol concentration enrichment system (VACES). The grown

  15. Direct night-time ejection of particle-phase reduced biogenic sulfur compounds from the ocean to the atmosphere.

    PubMed

    Gaston, Cassandra J; Furutani, Hiroshi; Guazzotti, Sergio A; Coffee, Keith R; Jung, Jinyoung; Uematsu, Mitsuo; Prather, Kimberly A

    2015-04-21

    The influence of oceanic biological activity on sea spray aerosol composition, clouds, and climate remains poorly understood. The emission of organic material and gaseous dimethyl sulfide (DMS) from the ocean represents well-documented biogenic processes that influence particle chemistry in marine environments. However, the direct emission of particle-phase biogenic sulfur from the ocean remains largely unexplored. Here we present measurements of ocean-derived particles containing reduced sulfur, detected as elemental sulfur ions (e.g., (32)S(+), (64)S2(+)), in seven different marine environments using real-time, single particle mass spectrometry; these particles have not been detected outside of the marine environment. These reduced sulfur compounds were associated with primary marine particle types and wind speeds typically between 5 and 10 m/s suggesting that these particles themselves are a primary emission. In studies with measurements of seawater properties, chlorophyll-a and atmospheric DMS concentrations were typically elevated in these same locations suggesting a biogenic source for these sulfur-containing particles. Interestingly, these sulfur-containing particles only appeared at night, likely due to rapid photochemical destruction during the daytime, and comprised up to ?67% of the aerosol number fraction, particularly in the supermicrometer size range. These sulfur-containing particles were detected along the California coast, across the Pacific Ocean, and in the southern Indian Ocean suggesting that these particles represent a globally significant biogenic contribution to the marine aerosol burden. PMID:25835033

  16. Large area nuclear particle detectors using ET materials

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The purpose of this SBIR Phase 1 feasibility effort was to demonstrate the usefulness of Quantex electron-trapping (ET) materials for spatial detection of nuclear particles over large areas. This demonstration entailed evaluating the prompt visible scintillation as nuclear particles impinged on films of ET materials, and subsequently detecting the nuclear particle impingement information pattern stored in the ET material, by means of the visible-wavelength luminescence produced by near-infrared interrogation. Readily useful levels of scintillation and luminescence outputs are demonstrated.

  17. A Plasma Window for Transmission of Radiation and Particle Beams from Vacuum to Atmosphere for Various Applications

    NASA Astrophysics Data System (ADS)

    Hershcovitch, Ady

    1997-11-01

    Many industrial and scientific processes like electron beam melting and welding, material modification by ion implantation, dry etching, and micro-fabrication, as well as generation of synchrotron radiation are performed almost exclusively in vacuum nowadays, since the electron and ion guns and their extractors must be kept at a reasonably high vacuum. Consequently, there are numerous drawbacks, among which are low production rates due to required pumping time, limits the vacuum volume sets on the size of target objects. In a small number of applications like non-vacuum electron beam welding, and various processes involving UV and x-ray radiation, thin vacuum walls or long stages of differential pumping are used. But, the resultant degradations of particle and radiation beams severely limit those applications. A novel apparatus, which utilized a short plasma arc, was successfully used to maintain a pressure of 7.6 x exp(-6) Torr in a vacuum chamber with a 2.36mm aperture to atmosphere, i.e., a plasma was successfully used to "plug" a hole to atmosphere while maintaining a reasonably high vacuum in the chamber. Successful transmission of charged particle beams from a vacuum through the plasma to atmosphere was accomplished. More details can be found in A. Hershcovitch, J. Appl. Physics 78, p. 5283 (1995). In addition to sustaining a vacuum atmosphere interface, the plasma has very strong lensing effect on charged particles. The plasma current generates an azimuthal magnetic field which exerts a radial Lorentz on charged particles moving parallel to the current channel. With proper orientation of the current direction, the Lorentz force is radially inward. This feature can be used to focus in beams to a very small spot size, and to overcome beam dispersion due to scattering by atmospheric atoms and molecules. Relatively hot plasma at the atmosphere boundary rarefies the atmospheric gases to further enhance particle beam propagation to the materials to target. Recent experimental results, with a plasma window coupled to a venturi, show a factor of three further enhancement in vacuum-atmosphere separation.

  18. Secondary Cosmic Ray Particles due to GCR Interactions in the Earth's Atmosphere

    SciTech Connect

    Battistoni, G.; Garzelli, M. V.; Muraro, S.; Sala, P. R. [University of Milano, Department of Physics, and INFN, Milan (Italy); Cerutti, F.; Ferrari, A.; Roesler, S. [CERN, Geneva (Switzerland); Fasso, A. [SLAC, Stanford, CA (United States); Lantz, M. [Chalmers University, Department of Fundamental Physics, Goteborg (Sweden); Pinsky, L. S. [University of Houston, Department of Physics, Houston, TX (United States); Ranft, J. [Siegen University, Fachbereich 7-Physik, Siegen (Germany)

    2008-01-24

    Primary GCR interact with the Earth's atmosphere originating atmospheric showers, thus giving rise to fluxes of secondary particles in the atmosphere. Electromagnetic and hadronic interactions interplay in the production of these particles, whose detection is performed by means of complementary techniques in different energy ranges and at different depths in the atmosphere, down to the Earth's surface.Monte Carlo codes are essential calculation tools which can describe the complexity of the physics of these phenomena, thus allowing the analysis of experimental data. However, these codes are affected by important uncertainties, concerning, in particular, hadronic physics at high energy. In this paper we shall report some results concerning inclusive particle fluxes and atmospheric shower properties as obtained using the FLUKA transport and interaction code. Some emphasis will also be given to the validation of the physics models of FLUKA involved in these calculations.

  19. Soot particles and their impacts on the mass cycle in the Tibetan atmosphere

    Microsoft Academic Search

    Daizhou Zhang; Yasunobu Iwasaka; Guangyu Shi

    2001-01-01

    Atmospheric aerosol particles in urban and mountain areas around Lhasa city (29.65°N, 91.13°E) in the Tibetan Plateau were collected in the summers of 1998 and 1999. The particles were analyzed with electron microscopes and an energy dispersive X-ray spectrometer. Individual particle morphology, elemental composition and mixture of sulfate and nitrate were investigated. In the urban area, soot particles emitted from

  20. Process for application of powder particles to filamentary materials

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M. (inventor); Snoha, John J. (inventor); Marchello, Joseph M. (inventor)

    1991-01-01

    This invention is a process for the uniform application of polymer powder particles to a filamentary material in a continuous manner to form a uniform composite prepreg material. A tow of the filamentary material is fed under carefully controlled tension into a spreading unit, where it is spread pneumatically into an even band. The spread filamentary tow is then coated with polymer particles from a fluidized bed, after which the coated filamentary tow is fused before take-up on a package for subsequent utilization. This process produces a composite prepreg uniformly without imposing severe stress on the filamentary material, and without requiring long, high temperature residence times for the polymer.

  1. Meteoric Material - One of the Least Explored Components of Planetary Atmospheres

    Microsoft Academic Search

    J. I. Moses; J. M. Grebowsky; W. D. Pesnell; A. L. Weisman

    2001-01-01

    Interplanetary dust particles (IDPs) continuously impact all the planets and their satellites in the solar system. In all planetary atmospheres IDPs leave their imprint as aerosols or smoke particles that are left behind when the IDPs do not ablate completely or when the ablated vapors recondense. In addition, in all atmospheres they produce ionization layers comprised of metallic ions, predominantly

  2. The effect of atmosphere on the creep deformation of a particle reinforced aluminum alloy matrix composites

    Microsoft Academic Search

    Norio Matsuda; Koichi Kikuchi; Satoshi Ishikawa; Mitsuru Saitoh

    2004-01-01

    Creep behavior of the 6061 aluminum alloy matrix composite reinforced by 10vol.% of alumina particles has been investigated at temperatures from 573 to 773K in air and Ar atmospheres. Creep curves, stress dependence of the minimum creep rate, microstructures after creep deformation and the effect of the atmospheres on the creep behavior were examined. Deformation around grain boundaries was estimated

  3. Particle size distributions formed by atmospheric hydrolysis of uranium hexafluoride

    Microsoft Academic Search

    C. K. Bayne; W. D. Bostick

    1985-01-01

    The probability model for particle size data is usually assumed to be lognormal. For Pickrell's (1982) UFâ data, the lognormal is inappropriate and Johnson's S\\/sub B\\/ frequency curves are shown to be suitable alternative models. The type of particle size measurement, either mass or number, is also an important consideration for modeling. Converting from one measurement type to the other

  4. Scanning Electron Microanalysis and Analytical Challenges of Mapping Elements in Urban Atmospheric Particles

    EPA Science Inventory

    Elemental mapping with energy-dispersive X-ray spectroscopy (EDX) associated with scanning electron microscopy is highly useful for studying internally mixed atmospheric particles. Presented is a study of individual particles from urban airsheds and the analytical challenges in q...

  5. Particle size distribution of major inorganic species in atmospheric aerosols from Majorca (Spain)

    Microsoft Academic Search

    J. Mateu; R. Forteza; V. Cerdfi; M. Colom-Altés

    1995-01-01

    Atmospheric aerosols collected by means of a cascade impaction system at the campus of the University of the Balearic Islands (Majorca, Spain) from November 1993 to February 1994 were analysed for chloride, nitrate, sulphate, ammonium, calcium, magnesium, sodium and potassium. Based on particle size distribution, the species studied were classified into three groups: (a) concentration decrease with particle size (sulphate

  6. Liquidliquid phase separation in atmospherically relevant particles consisting of organic species and inorganic salts

    E-print Network

    the fol- lowing trend in SRH values: (NH4)2SO4 NH4HSO4 NaCl NH4NO3, consistent with previous salting.6. Dependence on the OIR 58 2.7. Dependence on the particle size 60 2.8. Morphology 61 3. Laboratory studiesLiquid­liquid phase separation in atmospherically relevant particles consisting of organic species

  7. Determining the sources of atmospheric particles in Shanghai, China, from magnetic and geochemical properties

    Microsoft Academic Search

    Jiong Shu; John A. Dearing; Andrew P. Morse; Lizhong Yu; Nu Yuan

    2001-01-01

    The study describes an investigation into the sources of atmospheric particles collected at 11 sites across Shanghai, China, during one week in November 1998. Source ascription is based on mineral magnetic and geochemical properties, and a chemical mass balance (CMB) model. The CMB model shows that the main contributions to total suspended particles (TSPs) are products of coal combustion, with

  8. Mercury adsorption to elemental carbon (soot) particles and atmospheric particulate matter

    Microsoft Academic Search

    Christian Seigneur; Heike Abeck; Gary Chia; Martin Reinhard; Nicolas S. Bloom; Eric Prestbo; Pradeep Saxena

    1998-01-01

    An assessment of the adsorption\\/desorption of mercury onto\\/from particulate matter is presented. This assessment addresses both elemental carbon (soot) particles using published data and atmospheric particulate matter using new experimental data. Available experimental data on the adsorption of mercury onto elemental carbon particles have been reexamined in terms of their adsorption isotherms. The experimental data sets analyzed include experiments concerning

  9. Ion Densities and Particle Charges for Alpha Ionization in an Aerosol Atmosphere: Columnar Recombination Corrections

    Microsoft Academic Search

    Y. S. Mayya; W. Holländer

    1995-01-01

    Ionization by alpha sources in an environment containing small aerosol particles is of interest in aerosol neutralizes, particle chargers and atmospheric electricity. It is known that the conventional ion-balance equation is inadequate in describing the bulk ion densities for alpha sources in view of the columnar recombination process. An earlier self-consistent formulation to include this effect is extended to the

  10. Predictions of the electrical conductivity and charging of the cloud particles in Jupiter's atmosphere

    Microsoft Academic Search

    R. C. Whitten; W. J. Borucki; K. O'Brien; S. N. Tripathi

    2008-01-01

    The electrical conductivity and electrical charge on cloud particles (composed of ammonia, ammonium hydrosulfide, and water) in the atmosphere of Jupiter are computed for pressures between 5.5 and 0.1 bars. The source of ionization is galactic cosmic rays (GCR). The distribution of charge among the various reservoirs is a function of altitude and the total area of the aerosol particles.

  11. On the emission of amines from terrestrial vegetation in the context of atmospheric new particle formation

    NASA Astrophysics Data System (ADS)

    Neftel, Albrecht; Sintermann, Jörg

    2015-04-01

    Airborne amines, specifically methylamines (MAs), play a key role in atmospheric new particle formation (NPF) by stabilising small molecule clusters. Agricultural emissions are assumed to constitute the most important MA source, but given the short atmospheric residence time of MAs, they can hardly have a direct impact on NFP events observed in remote regions. High MA contents as well as emissions by plants have already been described in the 19th century. Strong MA emissions predominantly occur during flowering as part of a pollination strategy. The behaviour is species specific, but examples of such species are common and widespread. In addition, vegetative plant tissue exhibiting high amounts of MAs might potentially lead to significant emissions, and the decomposition of organic material could constitute another source for airborne MAs. These mechanisms would provide sources, which could be crucial for the amine's role in NPF, especially in remote regions. Knowledge about vegetation-related amine emissions is, however, very limited and thus it is also an open question how Global Change and the intensified cycling of reactive nitrogen over the last 200 years have altered amine emissions from vegetation with a corresponding effect on NPF.

  12. Effect of annealing atmospheres on cobalt ferrite nono-particles and their applications

    NASA Astrophysics Data System (ADS)

    Kumar, V.; Pant, R. P.; Jain, V. K.; Yadav, M. S.

    2008-12-01

    Cobalt ferrite nano-particles have been synthesized by co-precipitation and annealed in air and in an inert atmosphere. Change in the physical properties has been analyzed by various analytical techniques like XRD, TEM, VSM, etc. A significant change in the physical properties like structural, particle shape, size, magnetization and microwave absorption has been observed. The effect of annealing on other properties like Curie temperature, electrical conductivity is also investigated. Particles unannealed and annealed in air and in an inert atmosphere are studied for electromagnetic wave interference. Tables 3, Figs 3, Refs 18.

  13. [Atmospheric particle formation events in Nanjing during summer 2010].

    PubMed

    Wang, Hong-Lei; Zhu, Bin; Shen, Li-Juan; Kang, Han-Qing; Diao, Yi-Wei

    2012-03-01

    Feature of aerosol particle number concentration, condition and impact factor of new particle formation (NPF) were investigated in Nanjing during summer. In this study, aerosol particle number concentration and gaseous pollutants (O3, SO2 and NO2) measurements were carried out by Wide-Range Particle Spectrometer (WPS) and Differential Optical Absorption Spectroscopy (DOAS) in July 2010. Combining with observations from Automatic Weather Station and Backward Trajectory Simulation, the condition and impact factor of NPF were discussed. Results showed that the averaged 10-500 nm particle number concentration was 1.7 x 10(4) cm(-3), similar to some typical observation values in North American and Europe; the 10-25 nm particle number concentration accounted for 25% of the total number concentration. Six NPF events occurred during observation. We analyzed that stable wind speed and direction, strong solar radiation promoted the NPF. The humidity during NPF event varied from 50% to 70%. Results indicated that clean ocean air mass brought from easterly and southerly wind promoted the NPF by Backward Trajectory Model Simulation. During the NPF event, the 10 - 25 nm particle number concentration positively correlated with the concentration of SO2, and negatively correlated with O3, whereas poorly correlated with NO2. PMID:22624358

  14. Quantitative characterization of spatial distribution of particles in materials: Application to materials processing

    NASA Technical Reports Server (NTRS)

    Parse, J. B.; Wert, John A.

    1990-01-01

    Most engineering materials contain second phase particles or fibers which serve to reinforce the matrix phase. The effect of reinforcements on material properties is usually analyzed in terms of the average volume fraction and spacing of reinforcements, quantities which are global microstructural characteristics. However, material properties can also depend on local microstructural characteristics; for example, on how uniformly the reinforcing phase is distributed in the material. The analysis method will then be applied to a materials processing problem to discover how processing parameters can be selected to maximize redistribution of the reinforcing phase during processing. Several mathematical analysis methods could be adapted to the problem of characterizing the distribution of particles in materials. A tessellation-based method was selected. In the first phase of the investigation, a software package was written to automate the analysis. Typical results are shown. The analysis technique allows the degree to which particles are clustered together, the size and spacing of particle clusters, and the particle density in clusters to be found. The analysis methods were applied to computer-generated distributions and to a few real particle-containing materials. Methods for analyzing a nonuniform particle distribution in a material can be applied to two broad classes of materials science problems: understanding how the resulting particle distribution affects properties. The analysis method described is applied to a materials processing problem: how to select extrusion conditions to maximize the redistribution of reinforcing particles that are initially nonuniformly distributed. In addition, the tessellation-based method to analyze star distributions in spiral galaxies was adapted, illustrating the diverse types of problems to which the analysis method can be applied.

  15. Real-time measurement of correlated size and composition profiles of individual atmospheric aerosol particles

    Microsoft Academic Search

    Christopher A. Noble; Kimberly A. Prather

    1996-01-01

    In this paper, the unique real-time measurement capabilities of aerosol time-of-flight mass spectrometry (ATOFMS) for characterizing atmospheric aerosol particles are demonstrated. ATOFMS is used to obtain the aerodynamic size and chemical composition of individual aerosol particles sampled directly into the instrument from outdoors. Such measurements are made in-situ by combining a unique dual-laser aerodynamic particle sizing system to size and

  16. [Size distributions of organic carbon (OC) and elemental carbon (EC) in Shanghai atmospheric particles].

    PubMed

    Wang, Guang-Hua; Wei, Nan-Nan; Liu, Wei; Lin, Jun; Fan, Xue-Bo; Yao, Jian; Geng, Yan-Hong; Li, Yu-Lan; Li, Yan

    2010-09-01

    Size distributions of organic carbon (OC), elemental carbon (EC) and secondary organic carbon (SOC) in atmospheric particles with size range from < 0.49, 0.49-0.95, 0.95-1.50, 1.50-3.00, 3.00-7.20, > 7.20 microm, collected in Jiading District, Shanghai were determined. For estimating size distribution of SOC in these atmospheric particles, a method of determining (OC/EC)(pri) in atmospheric particles with different sizes was discussed and developed, with which SOC was estimated. According to the correlation between OC and EC, main sources of the particles were also estimated roughly. The size distributions of OC and SOC showed a bi-modal with peaks in the particles with size of < 0.49 microm and > 3.0 microm, respectively. EC showed both of a bi-modal and tri-modal. Compared with OC, EC was preferably enriched in particles with size of < 0.49 microm. Mass concentrations of OC and EC in fine particles (< 3.00 microm) accounted for 59.8%-80.0% and 58.1%-82.4% of those in total suspended particles. OC and EC were preferably enriched in fine particles (< 3.00 microm). The concentrations of SOC in the particles with different sizes accounted for 15.7%-79.1% of OC in the particles with corresponding size. Concentrations of SOC in fine aerosols (< 3.00 microm) and coarse aerosols (> 3.00 microm) accounted for 41.4% and 43.5% of corresponding OC. Size distributions of OC, EC and SOC showed time-dependence. The correlation between OC and EC showed that the main contribution to atmospheric particles in Jiading District derived from light petrol vehicles exhaust. PMID:21072915

  17. Numerical Investigation of Light Scattering by Atmospheric Particles

    E-print Network

    Liu, Chao

    2013-07-12

    (PSTD) for calculating scattering properties, its advantages and the elimination of the Gibbs phenomenon. The applicability of the parallelized PSTD implementation is investigated for both spherical and nonspherical particles over a wide range of sizes...

  18. Atmospheric fate of nuclei-mode particles estimated from the number concentrations and chemical composition of particles measured at roadside and background sites

    NASA Astrophysics Data System (ADS)

    Fushimi, Akihiro; Hasegawa, Shuichi; Takahashi, Katsuyuki; Fujitani, Yuji; Tanabe, Kiyoshi; Kobayashi, Shinji

    Number concentrations and size-resolved chemical compositions of atmospheric particles at a roadside site in Kawasaki City, Japan, and a background site 200 m away were measured in winter to estimate the atmospheric fate of nuclei-mode particles emitted from vehicles. Measurements with a scanning mobility particle sizer showed a sharp peak in nuclei-mode particles with a modal diameter of around 0.020 ?m at the roadside site; in contrast, no peak for nuclei-mode particles was observed at the background site. For chemical analysis, size-resolved particles were sampled by low-pressure impactors. Carbon analysis suggested that diesel exhaust particles contributed to both the roadside and background Stage 1 (S1; 0.030-0.060 ?m) particles. The ratios of organic carbon (OC) to total carbon (TC) increased for smaller particles, and were 28% and 51% for the roadside and the background S1 particles, respectively. It is likely that the OC/TC ratio for nuclei-mode particles was larger than for the S1 particles, and that OC was one of the major constituents of the nuclei-mode particles at the roadside site. From this result and the greater Kelvin effect for smaller particles, it is likely that nuclei-mode particles in the roadside atmosphere are more volatile than the S1 particles. Organic analysis of the size-resolved particles suggested that lubricating oil from vehicles affected the organic composition of both the roadside and background S1 particles, and that C 33n-alkane and more volatile organic compounds in the S1 particles partially evaporated in the atmosphere following the emission of the particles from diesel vehicles. It is likely that evaporation of the constituents (or possibly coagulation with pre-existing particles after shrinking by partial evaporation) of the nuclei-mode particles in the atmosphere was responsible for the absence of nuclei-mode particles in the background atmosphere.

  19. Formation and decomposition of hazardous chemical components contained in atmospheric aerosol particles.

    PubMed

    Pöschl, Ulrich

    2002-01-01

    Air particulate matter contains a wide range of substances, some of which pose a threat to human health. Chemical reactions occurring on aerosol particles in the atmosphere can transform hazardous components and increase or decrease their potential for adverse health effects. Especially organic compounds react readily with atmospheric oxidants, and since fine aerosol particles have a high surface-to-volume ratio, their chemical composition can be efficiently changed by interaction with trace gases such as ozone and nitrogen oxides. In this paper the concepts required to understand and describe the formation and decomposition of hazardous chemical components contained in atmospheric aerosol particles are outlined. The processes at work on a molecular level in the chemical transformation of atmospheric particle components are illustrated for soot and polycyclic aromatic compounds (PACs), in particular for benzo[a]pyrene (BaP) which is one of the most prominent hazardous pollutants in the class of polycyclic aromatic hydrocarbons (PAHs). Recent results on the reaction kinetics and mechanisms of BaP degradation by ozone and nitrogen dioxide are presented. These results indicate faster degradation by atmospheric oxidants than previously estimated, which implies a higher potential for sampling artifacts and underestimation of the actual atmospheric abundance of BaP and other PAHs. Thus human exposure close to the sources of these compounds such as busy roadways may be significantly higher than previously assumed. PMID:12184870

  20. HIGHWAY MOTOR VEHICLES AS SOURCES OF ATMOSPHERIC PARTICLES: PROJECTED TRENDS 1977 TO 2000

    EPA Science Inventory

    Highway motor vehicle emissions contribute to the total atmospheric particulate burden. The possible health and welfare effects of these emissions depend upon their composition and concentration in the atmosphere, the exposure of man and materials, and in some instances the lengt...

  1. A dynamical perspective on the energetic particles precipitation-middle atmosphere interaction

    NASA Astrophysics Data System (ADS)

    Karami, Khalil; Sinnhuber, Miriam; Versick, Stefan; Braesicke, Peter

    2015-04-01

    Energetic particles including protons, electrons and heavier ions, enter the Earth's atmosphere over polar region of both hemispheres, where the geomagnetic lines are considered to be open and connected to the interplanetary medium. This condition allows direct access for energetic particles of solar or galactic origin to directly deposit their own energy into the middle and upper atmosphere. Such particle precipitations can greatly disturb the chemical composition of the upper and middle atmosphere. At polar latitudes, these particles have the potential to penetrate from thermosphere deep into the mesosphere and in rare occasions into the stratosphere. The most important are changes to the budget of atmospheric nitric oxides, NOy, and to atmospheric reactive hydrogen oxides, HOx, which both contribute to ozone loss in the stratosphere and mesosphere. The chemistry-climate general circulation model ECHAM5/MESSy is used to investigate the impact of changed ozone concentration due to energetic particles precipitation on temperatures and wind fields. The simulated anomalies of both zonal mean temperature and zonal wind suggest that these changes are very unlikely to be caused in situ by ozone depletion and indirect dynamical condition is important. The results of our simulations suggests that ozone perturbation is a starting point for a chain of processes resulting in temperature and circulation changes in many areas of the atmosphere. Different dynamical analysis (e.g., frequency of sudden stratospheric warming, dates of stratospheric final warming, divergence of Eliassen-Palm flux and refractive index of planetary waves) are performed to investigate the impact of ozone anomaly originated from high energetic particle precipitation on middle atmospheric temperature and circulation.

  2. Permittivity and permeability measurements methods for particle accelerator related materials

    E-print Network

    Vollinger, C; Jensen, E

    2014-01-01

    For the special requirements related to particle accelerators, knowledge of the different material parameters of dielectrics and other materials are needed in order to carry out simulations during the design process of accelerator components. This includes also properties of magnetically biased ferrites of which usually little information is available about material characteristics, especially in magnetic bias fields. Several methods of measurement are discussed and compared of which some require delicate sample preparation whereas others can work with unmodified material shapes that makes those methods also suited for acceptance checks on incoming materials delivered by industry. Applications include characterization of different materials, as absorbers in which dielectric losses play an increasing role, as well as low frequency measurements on ferrites that are used for tunable cavities. We present results obtained from both broadband and resonant measurements on different materials determined in the same s...

  3. Heating of dust particles enclosed in icy material

    NASA Astrophysics Data System (ADS)

    Komle, N. I.; Ulamec, S.

    1989-02-01

    'Dirty ice' is known to exist on the surfaces of comet nuclei and on the surfaces of many natural satellites in the outer solar system. In this paper the thermal behavior of dark dust particles enclosed in icy material is studied under the assumption that a certain fraction of the solar radiation can penetrate the ice and heat the particle directly. It is found that the area contact between the particle and the ice must be quite small in order to heat even a 'large' particle significantly above the temperature of the surrounding bulk ice. Under realistic assumptions for the area contact parameter micron-sized particles become hardly hotter than the surrounding bulk ice.

  4. Fabrication of advanced particles and particle-based materials assisted by droplet-based microfluidics.

    PubMed

    Wang, Jing-Tao; Wang, Juan; Han, Jun-Jie

    2011-07-01

    Recent advances in the fabrication of complex particles and particle-based materials assisted by droplet-based microfluidics are reviewed. Monodisperse particles with expected internal structures, morphologies, and sizes in the range of nanometers to hundreds of micrometers have received a good deal of attention in recent years. Due to the capability of generating monodisperse emulsions and of executing precise control and operations on the suspended droplets inside the microchannels, droplet-based microfluidic devices have become powerful tools for fabricating complex particles with desired properties. Emulsions and multiple-emulsions generated in the microfluidic devices can be composed of a variety of materials including aqueous solutions, gels, polymers and solutions containing functional nanoparticles. They are ideal microreactors or fine templates for synthesizing advanced particles, such as polymer particles, microcapsules, nanocrystals, and photonic crystal clusters or beads by further chemical or physical operations. These particles are promising materials that may be applicable for many fields, such as photonic materials, drug delivery systems, and bio-analysis. From simple to complex, from spherical to nonspherical, from polymerization and reaction crystallization to self-assembly, this review aims to help readers be aware of the many aspects of this field. PMID:21618428

  5. Discrete Particle Swarm Optimization with Scout Particles for Library Materials Acquisition

    PubMed Central

    Lin, Bertrand M. T.

    2013-01-01

    Materials acquisition is one of the critical challenges faced by academic libraries. This paper presents an integer programming model of the studied problem by considering how to select materials in order to maximize the average preference and the budget execution rate under some practical restrictions including departmental budget, limitation of the number of materials in each category and each language. To tackle the constrained problem, we propose a discrete particle swarm optimization (DPSO) with scout particles, where each particle, represented as a binary matrix, corresponds to a candidate solution to the problem. An initialization algorithm and a penalty function are designed to cope with the constraints, and the scout particles are employed to enhance the exploration within the solution space. To demonstrate the effectiveness and efficiency of the proposed DPSO, a series of computational experiments are designed and conducted. The results are statistically analyzed, and it is evinced that the proposed DPSO is an effective approach for the studied problem. PMID:24072983

  6. Modelling the formation of organic particles in the atmosphere

    NASA Astrophysics Data System (ADS)

    Anttila, T.; Kerminen, V.-M.; Kulmala, M.; Laaksonen, A.; O'Dowd, C.

    2003-12-01

    A modelling study investigating the formation of organic particles from inorganic, thermodynamically stable clusters was carried out. A recently-developed theory, the so-called nano-Köhler theory, which describes a thermodynamic equilibrium between a nanometer-size cluster, water and water-soluble organic compound, was implemented in a dynamical model along with a treatment of the appropriate aerosol and gas-phase processes. The obtained results suggest that both gaseous sulphuric acid and organic vapours contribute to organic particle formation. The initial growth of freshly-nucleated clusters having a diameter around 1 nm is driven by condensation of gaseous sulphuric acid and by a lesser extent cluster self-coagulation. After the clusters have reached sizes of around 2 nm in diameter, low-volatile organic vapours start to condense spontaneously into the clusters, thereby accelerating their growth to detectable sizes. A shortage of gaseous sulphuric acid or organic vapours limit, or suppress altogether, the particle formation, since freshly-nucleated clusters are rapidly coagulated away by pre-existing particles. The obtained modelling results were applied to explaining the observed seasonal cycle in the number of aerosol formation events in a continental forest site.

  7. DETERMINATION OF THE STRONG ACIDITY OF ATMOSPHERIC FINE PARTICLES (

    EPA Science Inventory

    This report is a standardized methodology description for the determination of strong acidity of fine particles (less than 2.5 microns) in ambient air using annular denuder technology. his methodology description includes two parts: art A - Standard Method and Part B - Enhanced M...

  8. Origin of nitrocatechols and alkylated-nitrocatechols in atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Marchand, Nicolas; Sylvestre, Alexandre; Ravier, Sylvain; Detournay, Anais; Bruns, Emily; Temime-Roussel, Brice; Slowik, Jay; El Haddad, Imad; Prevot, Andre

    2013-04-01

    Biomass burning constitutes one of the major sources of aerosol particles in most of the environments during winter. If a lot of information is available in the literature on the primary fraction of biomass burning aerosol particles, almost nothing is known regarding the formation of Secondary Organic Aerosol (SOA) from the chemical mixture emitted by this source. Recently methylated nitrocatechol have been identified in atmospheric particles collected in winter. These compounds are strongly associated with biomass burning tracers such as levoglucosan and are suspected to be of secondary origin since they can be formed through the oxidation of cresol significantly emitted by biomass burning. However, nitrocatechols are particularly difficult to analyze using classical techniques like HPLC-MS or GC-MS. In the present study, we adopt a new analytical approach. Direct analysis in real time (DART), introduced by Cody et al. (2005), allows direct analysis of gases, liquids, solids and materials on surfaces. Thus, for particles collected onto filters, the sample preparation step is simplified as much as possible, avoiding losses and reducing to the minimum the analytical procedure time. Two analytic modes can be used. In positive mode, [MH]+ ions are formed by proton transfer reaction ; whereas in negative ionization mode, [MH]-, M- and [MO2]- ions are formed. DART source enables soft ionization and produces simple mass spectra suitable for analysis of complex matrices, like organic aerosol, in only a few seconds. For this study, the DART source was coupled to a Q-ToF mass spectrometer (Synapt G2 HDMS, Waters), with a mass resolution up to 40 000. The analysis of atmospheric aerosol samples, collected in Marseille during winter 2011 (APICE project), with the DART/Q-ToF approach highlighted the abundance of nitrocatechols and alkylated nitrocatechols. Their temporal trends were also very similar to those of levoglucosan or dihydroabietic acid well known tracers of biomass burning aerosol. If their biomass burning origin's is clearly established, their secondary origin remains still not totally clear. Smog chamber experiments were then conducted in the PSI facilities to investigate the aging of biomass burning emissions. The analysis of samples collected during these experiments using the DART/Q-ToF approach, confirmed that nitrocatechols and methylated nitrocatechols originate from biomass burning processes. More importantly our results confirm that nitrocatechols and their methylated derivatives are quasi exclusively from secondary origin. Considering the abundance of biomass burning primary aerosol, and the large fraction of unexplained SOA, this result is of prime importance. Cody. R., Laramée J. Nilles J. and Durst H. : Direct Analysis in Real Time (DARTtm) Mass Spectrometry, JOEL news, 2005, 40, 1, 8-12. Kitanovski Z., Grgic I., Yasmeen F., Claeys M. and Cusak A.: Development of a liquid chromatographic method based on ultraviolet-visible and electrospray ionization mass spectrometric detection for the identification of nitrocatechols and related tracers ion biomass burning atmospheric organic aerosol, Rapid Communication in Mass Spectrometry, 2012, 26, 793-804. Iinuma Y., Boge O., Grafe R. and Herrmann H.: Methyl-nitrocatechols : Atmospheric tracer coumpounds for biomass burnig secondary organic aerosols, Environmental Science and Technology, 2010, 44, 8453-8459.

  9. Applications of Complementary Analytical Techniques to Study Chemical Composition and Properties of Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Laskin, A.

    2008-12-01

    Aerosols are widely recognized as key elements in atmospheric environment. Chemical and morphological data of individual particles are of crucial importance for understanding of their formation, reactions, atmospheric history and aging. Microprobe analytical techniques have been extensively used in the past to characterize the size, morphology, phase and composition of particles collected in field and laboratory studies. These technique coupled with an appropriate time-resolved aerosol sampling are capable of generating time-resolved single-particle data, which then can be used to follow in detail the time evolution of specific types of aerosols. In this presentation we give a summary of recent research projects carried out in our laboratory that demonstrates how the use of complementary microprobe methods and other analytical techniques provides new insights into the atmospheric reactions of aerosols, their physical and chemical transformations, and how the obtained data is utilized to define future directions in laboratory and field studies of aerosols.

  10. A diffusion model for use with directional samplers. [particle dispersion in atmosphere

    NASA Technical Reports Server (NTRS)

    Anbar, D.

    1978-01-01

    The paper presents a mathematical model for describing dispersion processes of airborne particles in the atmosphere. The process is described as a superposition of independent Brownian motion processes with drifts and a boundary at zero. It is assumed that the terrain is flat and of a homogeneous roughness. All sources are assumed to be point sources. The time dependencies of emission rates, wind speed, wind direction, and atmospheric conditions are taken into account.

  11. Single particle size and fluorescence spectra from emissions of burning materials in a tube furnace to simulate burn pits

    NASA Astrophysics Data System (ADS)

    Pan, Yong-Le; Houck, Joshua D. T.; Clark, Pamela A.; Pinnick, Ronald G.

    2013-08-01

    A single-particle fluorescence spectrometer (SPFS) and an aerodynamic particle sizer were used to measure the fluorescence spectra and particle size distribution from the particulate emissions of 12 different burning materials in a tube furnace to simulate open-air burning of garbage. Although the particulate emissions are likely dominated by particles <1 ?m diameter, only the spectra of supermicron particles were measured here. The overall fluorescence spectral profiles exhibit either one or two broad bands peaked around 300-450 nm within the 280-650 nm spectral range, when the particles are illuminated with a 263-nm laser. Different burning materials have different profiles, some of them (cigarette, hair, uniform, paper, and plastics) show small changes during the burning process, and while others (beef, bread, carrot, Styrofoam, and wood) show big variations, which initially exhibit a single UV peak (around 310-340 nm) and a long shoulder in visible, and then gradually evolve into a bimodal spectrum with another visible peak (around 430-450 nm) having increasing intensity during the burning process. These spectral profiles could mainly derive from polycyclic aromatic hydrocarbons with the combinations of tyrosine-like, tryptophan-like, and other humic-like substances. About 68 % of these single-particle fluorescence spectra can be grouped into 10 clustered spectral templates that are derived from the spectra of millions of atmospheric aerosol particles observed in three locations; while the others, particularly these bimodal spectra, do not fall into any of the 10 templates. Therefore, the spectra from particulate emissions of burning materials can be easily discriminated from that of common atmospheric aerosol particles. The SFFS technology could be a good tool for monitoring burning pit emissions and possibly for distinguishing them from atmospheric aerosol particles.

  12. Qualitative multiplatform microanalysis of individual heterogeneous atmospheric particles from high-volume air samples.

    PubMed

    Conny, Joseph M; Collins, Sean M; Herzing, Andrew A

    2014-10-01

    High-resolution microscopic analysis of individual atmospheric particles can be difficult, because the filters upon which particles are captured are often not suitable as substrates for microscopic analysis. Described here is a multiplatform approach for microscopically assessing chemical and optical properties of individual heterogeneous urban dust particles captured on fibrous filters during high-volume air sampling. First, particles embedded in fibrous filters are transferred to polished silicon or germanium wafers with electrostatically assisted high-speed centrifugation. Particles are clustered in an array of deposit areas, which allows for easily locating the same particle with different microscopy instruments. Second, particles with light-absorbing and/or light-scattering behavior are identified for further study from bright-field and dark-field light-microscopy modes, respectively. Third, particles identified from light microscopy are compositionally mapped at high definition with field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. Fourth, compositionally mapped particles are further analyzed with focused ion-beam (FIB) tomography, whereby a series of thin slices from a particle are imaged, and the resulting image stack is used to construct a three-dimensional model of the particle. Finally, particle chemistry is assessed over two distinct regions of a thin FIB slice of a particle with energy-filtered transmission electron microscopy (TEM) and electron energy-loss spectroscopy associated with scanning transmission electron microscopy (STEM). PMID:25220253

  13. Detection of special nuclear materials with the associate particle technique

    SciTech Connect

    Carasco, Cedric; Deyglun, Clement; Perot, Bertrand; Eleon, Cyrille [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 St Paul-lez-Durance (France); Normand, Stephane; Sannie, Guillaume; Boudergui, Karim; Corre, Gwenole; Konzdrasovs, Vladimir [CEA, DRT, LIST, Saclay, F-91191 Gif-sur-Yvette (France); Pras, Philippe [CEA, DAM, DIF, F-91297 Arpajon (France)

    2013-04-19

    In the frame of the French trans-governmental R and D program against chemical, biological, radiological, nuclear and explosives (CBRN-E) threats, CEA is studying the detection of Special Nuclear Materials (SNM) by neutron interrogation with fast neutrons produced by an associated particle sealed tube neutron generator. The deuterium-tritium fusion reaction produces an alpha particle and a 14 MeV neutron almost back to back, allowing tagging neutron emission both in time and direction with an alpha particle position-sensitive sensor embedded in the generator. Fission prompt neutrons and gamma rays induced by tagged neutrons which are tagged by an alpha particle are detected in coincidence with plastic scintillators. This paper presents numerical simulations performed with the MCNP-PoliMi Monte Carlo computer code and with post processing software developed with the ROOT data analysis package. False coincidences due to neutron and photon scattering between adjacent detectors (cross talk) are filtered out to increase the selectivity between nuclear and benign materials. Accidental coincidences, which are not correlated to an alpha particle, are also taken into account in the numerical model, as well as counting statistics, and the time-energy resolution of the data acquisition system. Such realistic calculations show that relevant quantities of SNM (few kg) can be distinguished from cargo and shielding materials in 10 min acquisitions. First laboratory tests of the system under development in CEA laboratories are also presented.

  14. Characteristics of atmospheric ice nucleating particles associated with biomass burning in the US: Prescribed burns and wildfires

    NASA Astrophysics Data System (ADS)

    McCluskey, Christina S.; DeMott, Paul J.; Prenni, Anthony J.; Levin, Ezra J. T.; McMeeking, Gavin R.; Sullivan, Amy P.; Hill, Thomas C. J.; Nakao, Shunsuke; Carrico, Christian M.; Kreidenweis, Sonia M.

    2014-09-01

    An improved understanding of atmospheric ice nucleating particles (INP), including sources and atmospheric abundance, is needed to advance our understanding of aerosol-cloud-climate interactions. This study examines diverse biomass burning events to better constrain our understanding of how fires impact populations of INP. Sampling of prescribed burns and wildfires in Colorado and Georgia, U.S.A., revealed that biomass burning leads to the release of particles that are active as condensation/immersion freezing INP at temperatures from -32 to -12°C. During prescribed burning of wiregrass, up to 64% of INP collected during smoke-impacted periods were identified as soot particles via electron microscopy analyses. Other carbonaceous types and mineral-like particles dominated INP collected during wildfires of ponderosa pine forest in Colorado. Total measured nINP and the excess nINP associated with smoke-impacted periods were higher during two wildfires compared to the prescribed burns. Interferences from non-smoke sources of INP, including long-range transported mineral dust and local contributions of soils and plant materials lofted from the wildfires themselves, presented challenges in using the observations to develop a smoke-specific nINP parameterization. Nevertheless, these field observations suggest that biomass burning may serve as an important source of INP on a regional scale, particularly during time periods that lack other robust sources of INP such as long-range transported mineral dust.

  15. Method and apparatus for making articles from particle based materials

    DOEpatents

    Moorhead, Arthur J. (Knoxville, TN); Menchhofer, Paul A. (Oak Ridge, TN)

    1995-01-01

    A method and apparatus for the production of articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with the invention, a thermally settable slurry containing a relatively high concentration of the particles is conveyed through an elongate flow area having a desired cross-sectional configuration. The slurry is heated as it is advanced through the flow area causing the slurry to set or harden in a shape which conforms to the cross-sectional configuration of the flow area. The material discharges from the flow area as a self-supporting solid of near net final dimensions. The article may then be sintered to consolidate the particles and provide a high density product.

  16. Method and apparatus for making articles from particle based materials

    DOEpatents

    Moorhead, A.J.; Menchhofer, P.A.

    1995-12-19

    A method and apparatus are disclosed for the production of articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with the invention, a thermally settable slurry containing a relatively high concentration of the particles is conveyed through an elongate flow area having a desired cross-sectional configuration. The slurry is heated as it is advanced through the flow area causing the slurry to set or harden in a shape which conforms to the cross-sectional configuration of the flow area. The material discharges from the flow area as a self-supporting solid of near net final dimensions. The article may then be sintered to consolidate the particles and provide a high density product. 10 figs.

  17. Coulomb stable structures of charged dust particles in a dynamical trap at atmospheric pressure in air

    NASA Astrophysics Data System (ADS)

    Vasilyak, L. M.; Vladimirov, V. I.; Deputatova, L. V.; Lapitsky, D. S.; Molotkov, V. I.; Pecherkin, V. Ya; Filinov, V. S.; Fortov, V. E.

    2013-04-01

    A mathematical simulation of a dust particle's behavior in the electrodynamic linear quadrupole trap with closing end electrodes allowed us to reveal several features of the phenomena. Regions of stable confinement of a single particle, in dependence of frequency and charge-to-mass ratio, were determined. With an increase of the medium's dynamical viscosity, the region for confining charged particles by the trap becomes wider. We obtained values of the maximum quantities of charged particles confined by the trap at atmospheric pressure in air. Firstly, we presented observations of ordered Coulomb structures of charged dust particles obtained in the quadrupole trap in air at atmospheric pressure. The structures consisted of positively charged oxide aluminum particles 10-15 ?m in size and hollow glass microspheres 30-50 ?m in diameter. The ordered structure could contain particles of different sizes and charges. The trap could confine a limited number of charged particles. The ordered structures of charged micro-particles obtained in the experiments can be used to study Coulomb systems without neutralizing the plasma background and action of ion and electron flows, which are always present in non-homogeneous plasma.

  18. Are coarse particles unexpected common reservoirs for some atmospheric anthropogenic trace elements? A case study

    NASA Astrophysics Data System (ADS)

    Catinon, Mickaël; Ayrault, Sophie; Boudouma, Omar; Bordier, Louise; Agnello, Gregory; Reynaud, Stéphane; Tissut, Michel

    2013-08-01

    Without specific experimental equipment, it is very difficult to sample long-term atmospheric deposits on a pure state. That is why the composition of air-transferred solid material accumulated for 40 years in the 2 m-high walls, pierced with numerous holes of an outdoor public shelter, Grenoble city, France, was studied. An appropriate fractionation procedure allowed to obtain several fractions which were i) a sand fraction (8.3%) (fraction A), ii) a large mass of organic matter corresponding mostly to large fragments (>250 ?m) of plant origin (66.7%) (fraction B) or to pollen fraction C (0.4%), iii) a slowly depositing organo-clay fraction (20%) (fractions D1 and D2) and iv) a solution mixed with non-settable particles (4.3%) (fraction E). The composition of each fraction was determined for 20 elements. The sand fraction showed very high concentrations specifically in Cu, Pb and Fe corresponding respectively to 81.5, 48.2 and 35.2% of the samples content in these elements. In contrast, Cd and Zn were mainly accumulated in the fraction B (67.5 and 62.2%, respectively). The scanning electron microscopy coupled to energy dispersive X-ray analysis (SEM-EDX) study of the fraction A showed the presence of large particles bearing Pb and Fe, particles rich in Cu and typical fly ashes originating mostly from iron industry. Most of these particles had a crystalline shape suggesting that they were formed after emission at a high temperature. The Pb-Fe-Cu deposit seen in fraction A likely originates from the neighbouring road surface contaminated by car traffic for several decades. The 206Pb/207Pb ratio (1.146 ± 0.004) showed that in the coarse sandy fraction A, Pb was represented at 65% by non-gasoline lead and 35% by "gasoline" lead emitted before 1999. The fraction A particles can only be transported on a limited distance by high magnitude events. They constitute a large reservoir for Cu and Pb and may play a major role in the long-term contamination of urban soils.

  19. Electron Spectroscopy for Chemical Analysis (ESCA) study of atmospheric particles

    NASA Technical Reports Server (NTRS)

    Dillard, J. G.; Seals, R. D.; Wightman, J. P.

    1979-01-01

    The results of analyses by ESCA (Electron Spectroscopy for Chemical Analysis) on several Nuclepore filters which were exposed during air pollution studies are presented along with correlative measurements by Neutron Activation Analysis and Scanning Electron Microscopy. Samples were exposed during air pollution studies at Norfolk, Virginia and the NASA Kennedy Space Center (KSC). It was demonstrated that with the ESCA technique it was possible to identify the chemical (bonding) state of elements contained in the atmospheric particulate matter collected on Nuclepore filters. Sulfur, nitrogen, mercury, chlorine, alkali, and alkaline earth metal species were identified in the Norfolk samples. ESCA binding energy data for aluminum indicated that three chemically different types of aluminum are present in the launch and background samples from NASA-KSC.

  20. Ionization of the Earth's Upper Atmosphere in Large Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Wolff, E.; Burrows, J.; Kallenrode, M.; von Koenig, M.; Kuenzi, K. F.; Quack, M.

    2001-12-01

    Energetic charged particles ionize the upper terrestrial atmosphere. Sofar, chemical consequences of precipitating particles have been discussed for solar protons with energies up to a few hundred MeV. We present a refined model for the interaction of energetic particles with the atmosphere based on a Monte-Carlo simulation. The model includes higher energies and other particle species, such as energetic solar electrons. Results are presented for well-known solar events, such as July 14, 2000, and are extrapolated to extremely large events, such as Carrington's white light flare in 1859, which from ice cores has been identified ass the largest impulsive NO3 event in the interval 1561 -- 1994 (McCracken et al., 2001).

  1. 29 CFR 1917.23 - Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 2011-07-01 false Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or atmosphere). 1917.23 Section 1917.23...Operations § 1917.23 Hazardous atmospheres and substances (see also §...

  2. 29 CFR 1917.23 - Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 2012-07-01 false Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or atmosphere). 1917.23 Section 1917.23...Operations § 1917.23 Hazardous atmospheres and substances (see also §...

  3. 29 CFR 1917.23 - Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 2014-07-01 false Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or atmosphere). 1917.23 Section 1917.23...Operations § 1917.23 Hazardous atmospheres and substances (see also §...

  4. 29 CFR 1917.23 - Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 2010-07-01 false Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or atmosphere). 1917.23 Section 1917.23...Operations § 1917.23 Hazardous atmospheres and substances (see also §...

  5. 29 CFR 1917.23 - Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 2013-07-01 false Hazardous atmospheres and substances (see also § 1917.2 Hazardous cargo, material, substance or atmosphere). 1917.23 Section 1917.23...Operations § 1917.23 Hazardous atmospheres and substances (see also §...

  6. An Overview of Particle Beam Materials Processing Techniques*

    NASA Astrophysics Data System (ADS)

    Dylla, H. F.

    1996-05-01

    Materials processing techniques can lead to the development of new products, create new applications by modifying existing materials, and add significant value to existing product lines. Additionally, there is ever-increasing consumer and regulatory pressure to develop "greener" products utilizing "dry chemistry" which have reduced environmental impact, and where the production process yields only product and no waste. Such processing can result from the use of photons or elementary particles. Accelerated particle beams offer many diverse opportunities, to process materials if economic targets can be met. This mini-symposium, a joint endeavor of the APS Division of the Physics of Beams (DPB) and the Forum on Industrial and Applied Physics (FIAP), seeks to review these opportunities and the current state-of-the-art, by assembling leading practitioners of particle beam materials processing for review presentations. Beam processing areas covered in the symposium will include: electron beam processing of biomass, curing of composite materials, sterilization and other applications; ion beams and plasma accelerators for surface processing; proposed next-generation lithography tools that utilize either compact synchrotrons or small ion and electron accelerators; high-volume UV surface processing of polymers and metals using free-electron lasers or excimer lamps, and beam generation of tritium. * This work supported by U.S. DOE Contract No. DE-AC05-84ER40150.

  7. Atmospheric fate of oil matter adsorbed on sea salt particles under UV light

    NASA Astrophysics Data System (ADS)

    Vaitilingom, M.; Avij, P.; Huang, H.; Valsaraj, K. T.

    2014-12-01

    The presence of liquid petroleum hydrocarbons at the sea water surface is an important source of marine pollution. An oil spill in sea-water will most likely occur due to an involuntary accident from tankers, offshore platforms, etc. However, a large amount of oil is also deliberately spilled in sea-water during the clean-out process of tank vessels (e.g. for the Mediterranean Sea, 490,000 tons/yr). Moreover, the pollution caused by an oil spill does not only affect the aquatic environment but also is of concern for the atmospheric environment. A portion of the oil matter present at the sea-water surface is transported into the atmosphere viaevaporation and adsorption at the surface of sea spray particles. Few studies are related to the presence of oil matter in airborne particles resulting from their adsorption on sea salt aerosols. We observed that the non-volatile oil matter was adsorbed at the surface of sea-salt crystals (av. size of 1.1 ?m). Due to their small size, these particles can have a significant residence time in the atmosphere. The hydrocarbon matter adsorbed at the surface of these particles can also be transformed by catalyzers present in the atmosphere (i.e. UV, OH, O3, ...). In this work, we focused on the photo-oxidation rates of the C16 to C30alkanes present in these particles. We utilized a bubble column reactor, which produced an abundance of small sized bubbles. These bubbles generated droplets upon bursting at the air-salt water interface. These droplets were then further dried up and lifted to the top of the column where they were collected as particles. These particles were incubated in a controlled reactor in either dark conditions or under UV-visible light. The difference of alkane content analyzed by GC-MS between the particles exposed to UV or the particles not exposed to UV indicated that up to 20% in mass was lost after 20 min of light exposure. The degradation kinetics varied for each range of alkanes (C16-20, C21-25, C26-30) from 20 to 60 ?g L-1 min-1. To observe the effect on air composition when samples are exposed to solar light, experiments were conducted under controlled atmospheric conditions: oxygen free or with O3 gas. The results showed the importance of the photo-transformation processes of oil in airborne particles and its relation to the gaseous nature of the ambient atmosphere.

  8. Effect of Operating Conditions in Atmospheric Freeze Drying of Carrot Particles in a Pulsed Fluidized Bed

    Microsoft Academic Search

    Alejandro Reyes; Ricardo V. Vega; Rodrigo D. Bruna

    2010-01-01

    Drying kinetics and shrinkage of carrot particles during atmospheric freeze drying in a pulsed fluidized bed were studied by using a 2 factorial statistical design as a function of particle size (6 mm × 6 mm × 1.5 mm and 6 mm × 6 mm × 3 mm), freezing rate (slow and quick), air temperature (?15 and ?5°C), and type of energy supply (convective and convective with infrared radiation). Then, a programmed air temperature

  9. Multiangle Light-Scattering Measurements of Refractive Index of Submicron Atmospheric Particles

    Microsoft Academic Search

    William D. Dick; Paul J. Ziemann; Peter H. McMurry

    2007-01-01

    Multiangle light scattering (MLS) measurements of monodisperse atmospheric particles ranging in diameter from 0.2 to 0.8 ?m were made with the DAWN-A optical detector during the Southeastern Aerosol and Visibility Study (SEAVS). The study was conducted on the southwestern edge of the Great Smoky Mountains National Park from July 15 to August 25, 1995. Individual particles were separated into spherical

  10. Measuring the spectral emissivity of thermal protection materials during atmospheric reentry simulation

    NASA Technical Reports Server (NTRS)

    Marble, Elizabeth

    1996-01-01

    Hypersonic spacecraft reentering the earth's atmosphere encounter extreme heat due to atmospheric friction. Thermal Protection System (TPS) materials shield the craft from this searing heat, which can reach temperatures of 2900 F. Various thermophysical and optical properties of TPS materials are tested at the Johnson Space Center Atmospheric Reentry Materials and Structures Evaluation Facility, which has the capability to simulate critical environmental conditions associated with entry into the earth's atmosphere. Emissivity is an optical property that determines how well a material will reradiate incident heat back into the atmosphere upon reentry, thus protecting the spacecraft from the intense frictional heat. This report describes a method of measuring TPS emissivities using the SR5000 Scanning Spectroradiometer, and includes system characteristics, sample data, and operational procedures developed for arc-jet applications.

  11. Concentration and Gas-particle Partitioning of Atmospheric Polycyclic Aromatic Hydrocarbons in Relation to Monsoons

    NASA Astrophysics Data System (ADS)

    Ko, F. C.; Cheng, J. O.; Lee, C. L.

    2014-12-01

    The atmospheric concentrations and gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs) were determined in the Hengchun Peninsula of southern Taiwan. The concentrations of total suspended particle (TSP) and total PAH (t-PAH; gas + particulate) ranged from 1.6 to 78.8 ?g m-3 and 430 to 4400 pg m-3, respectively. The highest levels of t-PAH concentrations and particle-associated PAHs were found during the northeast (NE) monsoon season. Long-range transport and rainfall scavenging mechanisms could contribute to seasonal variations in TSP and t-PAH concentrations. Results from principal component analysis (PCA) indicated that air mass movement caused by the monsoon system was the main influence on atmospheric PAHs profiles and concentrations. Gas-particle partition coefficients (Kp) of PAHs were well-correlated with the sub-cooled liquid vapor pressures (PoL), suggesting that the gas-particle partition of PAHs follows the characteristic of PAHs. In addition, the partitioning of PAHs between gas and particle phases varied significantly between NE and SW monsoon seasons. This study sheds lights on the role of Asian monsoon regarding atmospheric transport of PAHs.

  12. The effect of particles and electromagnetic waves on vortex structures in the atmosphere and the ionosphere

    NASA Astrophysics Data System (ADS)

    Izhovkina, N. I.

    2015-05-01

    The formation of vortex structures in an inhomogeneous gyrotropic atmosphere was stochastically determined. Atmospheric gyrotropy is induced by the Coriolis force acting as the Earth rotates and the motion of charged particles in the geomagnetic field. Vortices of a plasma nature are observed in the atmosphere. The electric field of such plasma vortices originates within the fields of pressure gradients of a mosaic cell topology upon the ionization of particles. It is shown that waves in a neutral atmosphere, electric fields, and electromagnetic waves affect the stability of vortex structures. Wave signals from anthropogenic sources and smog may stimulate local precipitation upon the passage of a cloud front and weaken or strengthen vortex structures. The plasma vortex may capture charged particles of different masses. The charge separation in plasma vortex structures is driven by the polarization drift at the decay of electric fields. The self-focusing of plasma vortices upon the condensation of moisture in the atmospheric cloud cover leads to an increase in the energy of vortices.

  13. Haze Particles and Condensation in Pluto's Atmosphere Explored through Microphysical Modeling

    NASA Astrophysics Data System (ADS)

    Barth, E. L.

    2014-12-01

    To explore scenarios involving condensation in Pluto's atmosphere, a 1-D microphysics model based on the Community Aerosol and Radiation Model for Atmospheres (CARMA) has been developed. CARMA has been used successfully many times to explore the vertical distribution, size, shape, and composition of particles in Titan's atmosphere, and in particular, to predict the appearance of methane condensate layers which were observed at the Huygens' landing site. Physical processes in CARMA include nucleation, condensation, evaporation, sedimentation, and coagulation. In Pluto's atmosphere, most of the condensation would require the presence of a troposphere with at least a few kilometers vertical extent. However, if photochemical production proceeds similarly to the case of Titan's atmosphere, there are possibilities for condensation at higher altitudes as well. A number of sensitivity tests will be presented, including variations in the abundance, size, and shape of haze particles; evaluating the onset of homogeneous methane nucleation; exploring the size distribution of the resulting methane ice particles; and the effects of condensation of other photochemically produced trace species as well.

  14. Application of chemometric methods for classification of atmospheric particles based on thin-window electron probe microanalysis data

    Microsoft Academic Search

    J Osán; J de Hoog; A Worobiec; C.-U Ro; K.-Y Oh; I Szalóki; R Van Grieken

    2001-01-01

    Conventional single-particle electron probe microanalysis (EPMA) is widely used for evaluating the sources of atmospheric aerosol. The method is capable of simultaneously detecting the chemical composition and the morphology of each particle. Computer-controlled automatic EPMA allows the analysis of huge numbers of individual particles. Cluster as well as factor analysis are used for the classification of particles based on the

  15. Improving Atmospheric Plasma Spraying of Zirconate Thermal Barrier Coatings Based on Particle Diagnostics

    NASA Astrophysics Data System (ADS)

    Mauer, Georg; Sebold, Doris; Vaßen, Robert; Stöver, Detlev

    2012-06-01

    Lanthanum zirconate (La2Zr2O7) has been proposed as a promising material for thermal barrier coatings. During atmospheric plasma spraying (APS) of La2Zr2O7 a considerable amount of La2O3 can evaporate in the plasma flame, resulting in a non-stoichiometric coating. As indicated in the phase diagram of the La2O3-ZrO2 system, in the composition range of pyrochlore structure, the stoichiometric La2Zr2O7 has the highest melting point and other compositions are eutectic. APS experiments were performed with a TriplexPro™-200 plasma torch at different power levels to achieve different degrees of evaporation and thus stoichiometry. For comparison, some investigations on gadolinium zirconate (Gd2Zr2O7) were included, which is less prone to evaporation and formation of non-stoichiometry. Particle temperature distributions were measured by the DPV-2000 diagnostic system. In these distributions, characteristic peaks were detected at specific torch input powers indicating evaporation and solidification processes. Based on this, process parameters can be defined to provide stoichiometric coatings that show good thermal cycling performance.

  16. Morphology and Chemical composition of Atmospheric Particles over Semi-Arid region (Jaipur, Rajasthan) of India

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Agnihotri, R.; Yadav, P.; Singh, S.; Tawale, J. S.; Rashmi, R.; Prasad, M.; Arya, B. C.; Mishra, N.

    2012-12-01

    Uncertainties associated with the radiative forcing of atmospheric dust particles is highest, owing to lack of region-specific dust morphology (particle shape, size) and mineralogy (chemical composition) database, needed for modeling their optical properties (Mishra and Tripathi, 2008). To fill this gap for the Indian region, we collected atmospheric particles (with aerodynamic size <5um, PM5 and a few bulk particles; TSP) from seven sites of Jaipur and nearby locales (semi-arid region, in the vicinity of Thar Desert of Rajasthan) at varying altitude, during late winters of ca. 2012. PM5 particles were collected on Teflon filters (for bulk chemical analyses), while pure Tin substrates (~1×1 mm2) were used for investigating individual particle morphology. Using Scanning Electron Microscope equipped with Energy Dispersive X ray (SEM-EDX) facility at NPL, images of individual particles were recorded and the morphological parameters (e.g. Aspect ratio; AR, Circulatory parameter; CIR.) were retrieved following Okada et al. (2001), whereas chemical compositions of individual particles were determined by EDX and bulk samples by X ray fluorescence (XRF). The geometrical size distributions of atmospheric particles were generated for each site. Based on NIST (National Institute of Standard and Technology, USA) morphology database, the site-specific individual particle shapes reveal predominance of "Layered" (calcite and quartz rich), "Angular" structures (quartz rich) and "Flattened" particles over all the sites. Particles were found to be highly non-spherical with irregular shapes (CIR varying from 1 to 0.22 with median value ~0.76; AR varying from 1 to 5.4 with median value ~1.64). Noteworthy to mention, that unit values of AR and CIR represent spherical particles. Chemical analyses of PM5 particles revealed dominance of crustal elements e.g. Si, Al, Fe, Ca, Mg, in general. Particles over Kukas Hill (27.027° N, 75.919° E; ~800 MAGL) showed highest Fe mass fractions (~43%), i.e. a key element (in form of hematite; Fe2O3) for solar (visible) energy absorption and thus heating the atmosphere. The retrieved morphological parameters help to construct particle shape and number size distribution that are highly useful to reduce the uncertainty in radiative forcing of dust particles appreciably when combined with particle chemical composition as suggested by Kalashnikova and Sokolik (2004). References : Mishra, S. K., and S. N. Tripathi (2008), Modeling optical properties of mineral dust over the Indian Desert, J. Geophys. Res., 113, D23201, 19 PP., doi:10.1029/2008JD010048. Okada, K., J. Heintzenberg, K. Kai, and Y. Qin (2001), Shape of atmospheric mineral particles collected in three Chinese arid-regions, Geophys. Res. Lett., 28, 3123-3126 Kalashnikova OV, Sokolik IN. (2004) Modeling the radiative properties of nonspherical soil-derived mineral aerosols, J Quant Spectrosc Radiat Transfer, 87, 137-66.

  17. The effect of precipitating particles on middle atmospheric night time ozone during enhanced geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Daae, M.; Espy, P. J.; Newnham, D.; Kleinknecht, N.; Clilverd, M.

    2010-12-01

    We have investigated the effect of precipitating particles on middle atmospheric ozone during a moderate geomagnetic storm in July 2009. It is expected that the number of precipitating particles increases with increasing geomagnetic activity, and that these precipitated particles will subsequently enhance the production of nitrosonium (NO+) and odd hydrogen (HOx) in the upper atmosphere. The lifetime of HOx and its associated ozone (O3) destruction is short, whilst NO+ can form long-lived odd nitrogen during times of high geomagnetic activity, (NOx), which can affect ozone over a longer time span, and hence a wider spatial range due to transport. We use the National Oceanic and Atmospheric Administration (NOAA) satellite data to identify and analyze the particles that precipitated over Antarctica during the moderate geomagnetic storm. To analyze the subsequent nitric oxide (NO) enhancement and O3 depletion we use a microwave radiometer stationed at Troll, Antarctica (72°S, 2.5°E, L=4.76). This microwave radiometer operating at 250 GHz gives high temporal and vertical resolution of the NO and O3 column. The Atmospheric Radiation Transfer Simulator (ARTS) and QPack have been employed to perform the inversions of the spectra. During the July storm that reached -79 nT on the Dst index, we observe radiation-belt particle precipitation over Troll, an NO increase, and a direct O3 depletion of 30% between 60 and 80 km altitude. This O3 depletion lasted for 9 days, and its centroid descended to 55 km altitude at a vertical velocity of 1-3 m/s. This work shows that moderate storms, which are common-place and occur even during solar minimum, can cause a significant and direct effect in the middle atmospheric ozone distribution.

  18. A Lagrangian Stochastic Model for Heavy Particle Dispersion in the Atmospheric Marine Boundary Layer

    NASA Astrophysics Data System (ADS)

    Mueller, James A.; Veron, Fabrice

    2009-02-01

    The dispersion of heavy particles and pollutants is often simulated with Lagrangian stochastic (LS) models. Although these models have been employed successfully over land, the free surface at the air-sea interface complicates the implementation of traditional LS models. We present an adaptation of traditional LS models to the atmospheric marine boundary layer (MBL), where the bottom boundary is represented by a realistic wavy surface that moves and deforms. In addition, the correlation function for the turbulent flow following a particle is extended to the anisotropic, unsteady case. Our new model reproduces behaviour for Lagrangian turbulence in a stratified air flow that departs only slightly from the expected behaviour in isotropic turbulence. When solving for the trajectory of a heavy particle in the air flow, the modelled turbulent forcing on the particle also behaves remarkably well. For example, the spectrum of the turbulence at the particle location follows that of a massless particle for time scales approximately larger than the Stokes’ particle response time. We anticipate that this model will prove especially useful in the context of sea-spray dispersion and its associated momentum, sensible and latent heat, and gas fluxes between spray droplets and the atmosphere.

  19. Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling.

    PubMed

    Boone, Eric J; Laskin, Alexander; Laskin, Julia; Wirth, Christopher; Shepson, Paul B; Stirm, Brian H; Pratt, Kerri A

    2015-07-21

    Cloudwater and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry (HRMS) with nanospray desorption electrospray ionization (nano-DESI) and direct infusion electrospray ionization (ESI) were utilized to compare the organic composition of the particle and cloudwater samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloudwater, showing the significant influence of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloudwater samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloudwater when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol. PMID:26068538

  20. Relating atmospheric and oceanic DMS levels to particle nucleation events in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Chang, Rachel Y.-W.; Sjostedt, Steven J.; Pierce, Jeffrey R.; Papakyriakou, Tim N.; Scarratt, Michael G.; Michaud, Sonia; Levasseur, Maurice; Leaitch, W. Richard; Abbatt, Jonathan P. D.

    2011-09-01

    Measurements of ocean surface and atmospheric dimethyl sulfide (DMS) and particle size distributions were made in the Canadian Arctic Archipelago during the fall of 2007 and the late summer of 2008 aboard the Canadian Coast Guard Ship Amundsen. Nucleation-mode particles were observed during the 2008 cruise, which took place in the eastern Arctic from August to September when the atmosphere and ocean were more photo-active as compared to the October 2007 transit in the Beaufort Sea during which no nucleation/growth events were observed. The observed nucleation periods in 2008 coincided with high atmospheric and ocean surface DMS concentrations, suggesting that the particles originated from marine biogenic sources. An aerosol microphysics box model was used to simulate nucleation given the measured conditions in the marine boundary layer. Although other sources may have contributed, we find that the newly formed particles can be accounted for by a marine biogenic DMS source for combinations of the following parameters: [OH] ? 3 × 105 molecules cm-3, DMS mixing ratio is ? 100 pptv, the activation coefficient is ? 10-7 and the background particle concentration is ? 100 cm-3.

  1. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    SciTech Connect

    Farquar, G; Leif, R

    2009-07-15

    Biocompatible polymers with hydrolyzable chemical bonds have been used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres were produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  2. Investigation of surface discharges on different polymeric materials under HVAC in atmospheric air

    Microsoft Academic Search

    Hai-Bao Mu; Guan-Jun Zhang; Y. Komiyama; S. Suzuki; H. Miyake; Y. Tanaka; T. Takada

    2011-01-01

    Surface discharge on dielectric materials seriously restricts the performance of many electrical and electronic systems. Based on Pockels electro-optic effect, the surface discharge on polymeric insulating materials has been investigated under HVAC in Atmospheric Air. Different polymer materials such as polyimide (PI), polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF) films are employed. One single cycle of sinusoidal HVAC with peak

  3. Performance of Silver Nano Particles as an Electronics Packaging Interconnects Material

    Microsoft Academic Search

    Sungchul JooandDaniel; D. F. Baldwin

    2007-01-01

    Silver nano particle materials are investigated for use in microelectronics packaging as an innovative lead-free interconnect material. The nano particle materials were evaluated in terms of mechanical, electrical, metallurgical, and reliability performance. The silver nano particles are around 8 nm in diameter and are sintered at a temperature of 230 C to form material nearly indistinguishable from the bulk metal.

  4. Advanced Process Technology: Combi Materials Science and Atmospheric Processing (Fact Sheet)

    SciTech Connect

    Not Available

    2011-06-01

    Capabilities fact sheet for the National Center for Photovoltaics: Process Technology and Advanced Concepts -- High-Throughput Combi Material Science and Atmospheric Processing that includes scope, core competencies and capabilities, and contact/web information.

  5. Venus Atmospheric Maneuverable Platform (VAMP) — Stowage/Deployment Concepts and Materials Investigation

    NASA Astrophysics Data System (ADS)

    Bolisay, L. B.; Barnes, N. C.; Sokol, D. H.; Lee, G. J.; Polidan, R. S.

    2014-06-01

    This presentation discusses the continued development of the Northrop Grumman/L'GARDE team's long-lived, maneuverable platform to explore the Venus upper atmosphere. It focuses on vehicle stowage and deployment concepts, and materials investigation.

  6. Online Supplementary Material Properties of the Jovian atmosphere and vortices

    E-print Network

    Marcus, Philip S.

    |z=H of the atmosphere at the elevation of the top of the vortex and at the latitude of the principal east-west axis are not axisymmet- ric because they are embedded in strongly shearing east-west winds, it is necessary to consider the density difference, and the second approximate equality comes from the definitions of the buoyancy

  7. Mass-particle size distributions of atmospheric dust and the dry deposition of dust to the remote ocean

    NASA Astrophysics Data System (ADS)

    Arimoto, R.; Ray, B. J.; Lewis, N. F.; Tomza, U.; Duce, R. A.

    1997-07-01

    Size-separated mineral aerosol samples were collected and analyzed to investigate the relationships between the mass-particle size distributions (MSDs) of dust particles and the dust loadings in the atmosphere. The data also were used to assess the changes in the MSDs of dust in relation to transport processes and especially the associated effects on dry deposition. Atmospheric dust concentrations, as indicated by aluminum or scandium, in samples collected from three sites in the remote North Atlantic were higher than those in samples collected during a cruise in the North Pacific on board the R/V Moana Wave. However, the mass median diameters (MMDs) for the North Pacific samples were both larger on average (˜3 ?m versus ˜2 ?m aerodynamic equivalent diameter) and more variable than those from the North Atlantic; this difference was attributed to wet conditions and particle aggregation over the North Pacific. In addition, for the ensemble of all samples the geometric standard deviations of the mass-particle size distributions, which are analogous to the sorting values used to characterize sedimentary materials, tended to vary inversely and nonlinearly with the mass median diameters. Model-derived dry deposition velocities for the samples were at most weakly related to either the dust concentrations or the MMDs. However, the dry deposition velocities for two subsets of samples were correlated with the geometric standard deviations of the distributions; this is further evidence that the mass flux of dust via dry deposition can be controlled by a relatively small fraction of aerodynamically large particles.

  8. Field and laboratory studies of atmospheric reactive mercury: Gas-particle partitioning and sources

    NASA Astrophysics Data System (ADS)

    Rutter, Andrew Philip

    Certain aspects of atmospheric reactive mercury (RM) source-receptor relationships are not well understood. The objective of this dissertation was to improve the understanding of these relationships in the following areas: (i) gas-particle partitioning, and; (ii) the local impacts of RM source emissions. A novel aerosol reactor was developed to study gas-particle partitioning of RM using synthetic atmospheric aerosol containing picogram concentrations of RM. The RM in the aerosol was collected in an offline mode with filters and sorbent, and analyzed with Thermal Desorption Analysis (TDA). The offline-TDA collection and analysis method was compared with a commercial real time ambient mercury analyzer and two wet analysis methods using ambient measurements. The offline-TDA method performed well in comparison to the established techniques. The dependencies of gas-particle partitioning coefficients upon temperature and particle composition were determined and parameterized from field studies and laboratory experiments. The volatility of RM increased with ambient temperature in urban aerosol and laboratory aerosol of ammonium sulfate and adipic acid. The dependence of RM gas-particle partitioning on particle composition were determined using synthetic atmospheric aerosol generated in the laboratory. RM partitioned predominantly to the particle phase in particles of sodium nitrate, sodium chloride and potassium chloride, but was much more volatile in particles made of ammonium sulfate, levoglucosan and adipic acid. The impacts of RM sources on local receptors were studied in southern Wisconsin and Mexico City. RM measurements were made over a year in Milwaukee, WI (urban) and Devil's Lake State Park, WI (rural). An urban excess of all three mercury species was detected in Milwaukee, WI. The urban excess was attributed to a higher density of mercury emissions in the Milwaukee, WI-Chicago, IL area. The impact of local sources of RM on both sites was found to dominate the atmospheric concentrations. PHg and RGM measurements were made in Mexico City over 2.5 weeks. Diurnal concentration variations with nocturnal maxima pointed to nightly transport of air into the city from the industrial area to the north. RM partitioned predominantly to the particle phase in most of the plumes.

  9. Estimating bacteria emissions from inversion of atmospheric transport: sensitivity to modelled particle characteristics

    NASA Astrophysics Data System (ADS)

    Burrows, S. M.; Rayner, P. J.; Butler, T.; Lawrence, M. G.

    2013-06-01

    Model-simulated transport of atmospheric trace components can be combined with observed concentrations to obtain estimates of ground-based sources using various inversion techniques. These approaches have been applied in the past primarily to obtain source estimates for long-lived trace gases such as CO2. We consider the application of similar techniques to source estimation for atmospheric aerosols, using as a case study the estimation of bacteria emissions from different ecosystem regions in the global atmospheric chemistry and climate model ECHAM5/MESSy-Atmospheric Chemistry (EMAC). Source estimation via Markov Chain Monte Carlo is applied to a suite of sensitivity simulations, and the global mean emissions are estimated for the example problem of bacteria-containing aerosol particles. We present an analysis of the uncertainties in the global mean emissions, and a partitioning of the uncertainties that are attributable to particle size, activity as cloud condensation nuclei (CCN), the ice nucleation scavenging ratios for mixed-phase and cold clouds, and measurement error. For this example, uncertainty due to CCN activity or to a 1 ?m error in particle size is typically between 10% and 40% of the uncertainty due to observation uncertainty, as measured by the 5-95th percentile range of the Monte Carlo ensemble. Uncertainty attributable to the ice nucleation scavenging ratio in mixed-phase clouds is as high as 10-20% of that attributable to observation uncertainty. Taken together, the four model parameters examined contribute about half as much to the uncertainty in the estimated emissions as do the observations. This was a surprisingly large contribution from model uncertainty in light of the substantial observation uncertainty, which ranges from 81-870% of the mean for each of ten ecosystems for this case study. The effects of these and other model parameters in contributing to the uncertainties in the transport of atmospheric aerosol particles should be treated explicitly and systematically in both forward and inverse modelling studies.

  10. Nature of the Martian surface as inferred from the particle-size distribution of lunar-surface material.

    NASA Technical Reports Server (NTRS)

    Mason, C. C.

    1971-01-01

    Analysis of lunar particle size distribution data indicates that the surface material is composed of two populations. One population is caused by comminution from the impact of the larger-sized meteorites, while the other population is caused by the melting of fine material by the impact of smaller-sized meteorites. The results are referred to Mars, and it is shown that the Martian atmosphere would vaporize the smaller incoming meteorites and retard the incoming meteorites of intermediate and large size, causing comminution and stirring of the particulate layer. The combination of comminution and stirring would result in fine material being sorted out by the prevailing circulation of the Martian atmosphere and the material being transported to regions where it could be deposited. As a result, the Martian surface in regions of prevailing upward circulation is probably covered by either a rubble layer or by desert pavement; regions of prevailing downward circulation are probably covered by sand dunes.

  11. The generation of diesel exhaust particle aerosols from a bulk source in an aerodynamic size range similar to atmospheric particles.

    PubMed

    Cooney, Daniel J; Hickey, Anthony J

    2008-01-01

    The influence of diesel exhaust particles (DEP) on the lungs and heart is currently a topic of great interest in inhalation toxicology. Epidemiological data and animal studies have implicated airborne particulate matter and DEP in increased morbidity and mortality due to a number of cardiopulmonary diseases including asthma, chronic obstructive pulmonary disorder, and lung cancer. The pathogeneses of these diseases are being studied using animal models and cell culture techniques. Real-time exposures to freshly combusted diesel fuel are complex and require significant infrastructure including engine operations, dilution air, and monitoring and control of gases. A method of generating DEP aerosols from a bulk source in an aerodynamic size range similar to atmospheric DEP would be a desirable and useful alternative. Metered dose inhaler technology was adopted to generate aerosols from suspensions of DEP in the propellant hydrofluoroalkane 134a. Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm. Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process. Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene) in the particles resulting from the aerosolization process. PMID:19337412

  12. The generation of diesel exhaust particle aerosols from a bulk source in an aerodynamic size range similar to atmospheric particles

    PubMed Central

    Cooney, Daniel J; Hickey, Anthony J

    2008-01-01

    The influence of diesel exhaust particles (DEP) on the lungs and heart is currently a topic of great interest in inhalation toxicology. Epidemiological data and animal studies have implicated airborne particulate matter and DEP in increased morbidity and mortality due to a number of cardiopulmonary diseases including asthma, chronic obstructive pulmonary disorder, and lung cancer. The pathogeneses of these diseases are being studied using animal models and cell culture techniques. Real-time exposures to freshly combusted diesel fuel are complex and require significant infrastructure including engine operations, dilution air, and monitoring and control of gases. A method of generating DEP aerosols from a bulk source in an aerodynamic size range similar to atmospheric DEP would be a desirable and useful alternative. Metered dose inhaler technology was adopted to generate aerosols from suspensions of DEP in the propellant hydrofluoroalkane 134a. Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm. Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process. Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene) in the particles resulting from the aerosolization process. PMID:19337412

  13. Reports of workshops on Probe Measurements of Particles and Radiation in the Atmosphere of Titan

    NASA Technical Reports Server (NTRS)

    Ragent, Boris (comp. and ed.); Swenson, Byron L. (comp. and ed.)

    1990-01-01

    The planned 1995 joint ESA-NASA Cassini mission to the Saturnian system will include an atmospheric probe to be dropped into the atmosphere of Titan for in situ measurements during descent. Because of the unique properties of the Titan atmosphere it is necessary to consider the peculiar requirements for such measurements and applicable techniques. The proceedings of two workshops dealing with the measurement of particles and radiation in the atmosphere of Titan are presented in two parts. The first part dealt with the measurement of particulate matter in the atmosphere of Titan. The second part dealt with the measurement of radiation in the atmosphere of Titan. The proceedings were first published and distributed informally, and are presented with only minor editorial changes. In the report of the particulate matter workshop, discussions of the mission background, the importance of the measurements, and descriptions of the desired information are followed by a description of appropriate measurement techniques and conclusions and recommendations. The proceeding for the workshop on radiation measurement and imaging contains a discussion of the importance of radiation measurements and imaging, and presents a summary of participants' experience with such measurements made from entry probes. This is followed by a description of appropriate measurement techniques and conclusions and recommendations.

  14. Thermal infrared constraints on ammonia ice particles as candidates for clouds in the atmosphere of Saturn

    NASA Astrophysics Data System (ADS)

    Orton, G. S.

    1983-02-01

    Saturn atmosphere thermal IR emission observations have uncovered two phenomena that may be accounted for by large ammonia ice particles: the depression of thermal brightness near the equator, and inconsistent IR and radio occultation results. Ammonia ice particles yield the opacity that can account for the contrast between the equatorial region and a brighter area near 15 deg S, and may also reconcile the 45-micron brightness of these two regions with the mean temperature structure of Voyager 2 radio occultation results. A cloud model whose ice particles are distributed in an equal ratio with gas particles up to the 100 mbar pressure level is found to fit the equatorial data, while a thinner cloud, or one that does not extend higher than the 400 mbar limit of the convective region matches the 15 deg S data.

  15. Dynamics of Space Particles and Spacecrafts Passing by the Atmosphere of the Earth

    PubMed Central

    Prado, Antonio Fernando Bertachini de Almeida; Golebiewska, Justyna

    2013-01-01

    The present research studies the motion of a particle or a spacecraft that comes from an orbit around the Sun, which can be elliptic or hyperbolic, and that makes a passage close enough to the Earth such that it crosses its atmosphere. The idea is to measure the Sun-particle two-body energy before and after this passage in order to verify its variation as a function of the periapsis distance, angle of approach, and velocity at the periapsis of the particle. The full system is formed by the Sun, the Earth, and the particle or the spacecraft. The Sun and the Earth are in circular orbits around their center of mass and the motion is planar for all the bodies involved. The equations of motion consider the restricted circular planar three-body problem with the addition of the atmospheric drag. The initial conditions of the particle or spacecraft (position and velocity) are given at the periapsis of its trajectory around the Earth. PMID:24396298

  16. Strong atmospheric disturbances as a possible origin of inner zone particle diffusion

    NASA Astrophysics Data System (ADS)

    Pokhotelov, O. A.; Pilipenko, V. A.; Parrot, M.

    1999-04-01

    A new mechanism of the atmosphere-magnetosphere interaction, which might be called acoustic-magnetospheric cyclotron accelerator , is proposed. The idea of this mechanism stems from the fact that strong acoustical perturbations in the ionosphere (e.g., due to earthquakes, thunderstorms, etc.) may generate magnetic disturbances in the magnetosphere. Then, the latter will induce local resonant acceleration and subsequent inward diffusion of trapped particles. This idea may be fruitful in the interpretation of some occasional increases in inner zone particle fluxes which do not correlate with the solar or magnetospheric activities.

  17. Particle acceleration and transport in reconnecting twisted loops in a stratified atmosphere

    E-print Network

    Gordovskyy, Mykola; Kontar, Eduard; Bian, Nicolas

    2015-01-01

    Twisted coronal loops should be ubiquitous in the solar corona. Twisted magnetic fields contain excess magnetic energy, which can be released during magnetic reconnection, causing solar flares. The aim of this work is to investigate magnetic reconnection, and particle acceleration and transport in kink-unstable twisted coronal loops, with a focus on the effects of resistivity, loop geometry and atmospheric stratification. Another aim is to perform forward-modelling of bremsstrahlung emission and determine the structure of hard X-ray sources. We use a combination of magnetohydrodynamic (MHD) and test-particle methods. First, the evolution of the kinking coronal loop is considered using resistive MHD model, incorporating atmospheric stratification and loop curvature. Then, the obtained electric and magnetic fields and density distributions are used to calculate electron and proton trajectories using a guiding-centre approximation, taking into account Coulomb collisions. It is shown that electric fields in twist...

  18. Estimating the contribution of photochemical particle formation to ultrafine particle number averages in an urban atmosphere.

    PubMed

    Ma, N; Birmili, W

    2015-04-15

    Ultrafine particles (UFPs, diameter<100 nm) have gained major attention in the environmental health discussion due to a number of suspected health effects. Observations of UFPs in urban air reveal the presence of several, time-dependent particle sources. In order to attribute measured UFP number concentrations to different source type contributions, we analyzed observations collected at a triplet of observation sites (roadside, urban background, rural) in the city of Leipzig, Germany. Photochemical new particle formation (NPF) events can be the overwhelming source of UFP particles on particular days, and were identified on the basis of characteristic patterns in the particle number size distribution data. A subsequent segmentation of the diurnal cycles of UFP concentration yielded a quantitative contribution of NPF events to daily, monthly, and annual mean values. At roadside, we obtained source contributions to the annual mean UFP number concentration (diameter range 5-100 nm) for photochemical NPF events (7%), local traffic (52%), diffuse urban sources (20%), and regional background (21%). The relative contribution of NPF events rises when moving away from roadside to the urban background and rural sites (14 and 30%, respectively). Their contribution also increases when considering only fresh UFPs (5-20 nm) (21% at the urban background site), and conversely decreases when considering UFPs at bigger sizes (20-100 nm) (8%). A seasonal analysis showed that NPF events have their greatest importance on UFP number concentration in the months May-August, accounting for roughly half of the fresh UFPs (5-20 nm) at the urban background location. The simplistic source apportionment presented here might serve to better characterize exposure to ambient UFPs in future epidemiological studies. PMID:25617781

  19. Thermal and mechanical loading of particle and RF transmission windows exposed to atmospheric pressure

    Microsoft Academic Search

    R. J. Vidmar

    1997-01-01

    Summary form only given. The mechanical design of a transmission window that seals a port between a low-pressure side and an atmospheric-pressure side for the purpose of passing a high-energy particle beam or radio-frequency waves has many forms. Thermal loading due to energy loss from the beam or the waves and mechanical loading due to the pressure differential across the

  20. Condensation-nuclei (Aitken Particle) measurement system used in NASA global atmospheric sampling program

    NASA Technical Reports Server (NTRS)

    Nyland, T. W.

    1979-01-01

    The condensation-nuclei (Aitken particle) measuring system used in the NASA Global Atmospheric Sampling Program is described. Included in the paper is a description of the condensation-nuclei monitor sensor, the pressurization system, and the Pollack-counter calibration system used to support the CN measurement. The monitor has a measurement range to 1000 CN/cm cubed and a noise level equivalent to 5 CN/cm cubed at flight altitudes between 6 and 13 km.

  1. COMPASS - COMparative Particle formation in the Atmosphere using Simulation chamber Study techniques

    NASA Astrophysics Data System (ADS)

    Bonn, B.; Sun, S.; Haunold, W.; Sitals, R.; van Beesel, E.; dos Santos, L.; Nillius, B.; Jacobi, S.

    2013-06-01

    The anthropogenic influence on climate and environment has increased strongly since industrialization about 150 yr ago. The consequences for the atmosphere became more and more apparent and nowadays affect our life quality on Earth progressively. Because of that it is very important to understand the atmospheric processes, on which these effects are based on, in detail. In this study we report the set-up of a novel twin chamber technique that uses the comparative method and establishes an appropriate connection of atmospheric and laboratory methods to broaden the tools for investigations. It is designed to study the impact of certain parameters and gases on ambient processes such as particle formation online and can be applied in a large variety of conditions. The characterisation of both chambers proved that both chambers operate identically with a residence time (xT (COMPASS 1) = 26.5 ± 0.3 min and xT (COMPASS 2) = 26.6 ± 0.4 min) at a typical flow rate of 15 L min-1 and a deposition rate (1.6 ± 0.8) × 10-5 s-1. Comparison measurement showed no significant differences. Therefore operation under atmospheric conditions is trustworthy. To indicate the applicability and the benefit of the system a set of experiments was conducted at different conditions, i.e. urban and remote, enhancing ozone and terpenes as well as reducing sunlight. In the ozone enhanced ambient particle number and volume increased substantially at urban and remote conditions in a different strength. Solar radiation displayed a clear positive effect on particle number as well as terpene addition did at remote conditions. Therefore the system is a useful tool to investigate local precursors, the details of ambient particle formation at surface locations as well as future feedback processes.

  2. Chemical imaging analysis of environmental particles using the focused ion beam/scanning electron microscopy technique: microanalysis insights into atmospheric chemistry of fly ash.

    PubMed

    Chen, Haihan; Grassian, Vicki H; Saraf, Laxmikant V; Laskin, Alexander

    2013-01-21

    Airborne fly ash from coal combustion may represent a source of bioavailable iron (Fe) in the open ocean. However, few studies have focused on Fe speciation and distribution in coal fly ash. In this study, chemical imaging of fly ash has been performed using a dual-beam focused ion beam/scanning electron microscope (FIB/SEM) system for a better understanding of how simulated atmospheric processing can modify the morphology, chemical composition and element distribution within individual particles. A novel approach has been applied for cross-sectioning fly ash particles with the FIB in order to explore element distribution within the interior of individual particles. Our results indicate that simulated atmospheric processing can cause disintegration of aluminosilicate glass, a dominant material in fly ash particles. Fe present in the inner core of fly ash spheres within the aluminosilicate phase is more easily mobilized compared with Fe oxides present as surface aggregates on the exterior of fly ash spheres. Fe dissolution depends strongly on Fe speciation in fly ash particles. The approach for preparation of a cross-sectioned specimen described here opens up new opportunities for particle microanalysis, particularly with respect to inorganic refractive materials like fly ash and mineral dust. PMID:23207643

  3. Chemical Imaging Analysis of Environmental Particles Using the Focused Ion Beam/Scanning Electron Microscopy Technique: Microanalysis Insights into Atmospheric Chemistry of Fly Ash

    SciTech Connect

    Chen, Haihan; Grassian, Vicki H.; Saraf, Laxmikant V.; Laskin, Alexander

    2013-01-21

    Airborne fly ash from coal combustion may represent a source of bioavailable iron (Fe) in the open ocean. However, few studies have been made focusing on Fe speciation and distribution in coal fly ash. In this study, chemical imaging of fly ash has been performed using a dual-beam FIB/SEM (focused ion beam/scanning electron microscope) system for a better understanding of how simulated atmospheric processing modify the morphology, chemical compositions and element distributions of individual particles. A novel approach has been applied for cross-sectioning of fly ash specimen with a FIB in order to explore element distribution within the interior of individual particles. Our results indicate that simulated atmospheric processing causes disintegration of aluminosilicate glass, a dominant material in fly ash particles. Aluminosilicate-phase Fe in the inner core of fly ash particles is more easily mobilized compared with oxide-phase Fe present as surface aggregates on fly ash spheres. Fe release behavior depends strongly on Fe speciation in aerosol particles. The approach for preparation of cross-sectioned specimen described here opens new opportunities for particle microanalysis, particular with respect to inorganic refractive materials like fly ash and mineral dust.

  4. Organic films on atmospheric aerosol particles, fog droplets, cloud droplets, raindrops, and snowflakes

    NASA Astrophysics Data System (ADS)

    Gill, P. S.; Graedel, T. E.; Weschler, C. J.

    1983-05-01

    If surface-active organic molecules are present as surface films, the transfer of gases into the atmospheric water system could be impeded, evaporation could be slowed, and the aqueous chemical reactions could be influenced. The results of new measurements of the surface tension of aqueous solutions of common atmospheric organic compounds (beta-pinene, n-hexanol, eugenol, and anethole) are reported, and it is shown that the compounds produce films with properties similar to those of the better known surfactants. It is concluded that organic films are probably common on atmospheric aerosol particles and that they may occur under certain circumstances on fog droplets, cloud droplets, and snowflakes. If they are present, they will increase the lifetimes of aerosol particles, fog droplets, and cloud droplets, both by inhibiting water vapor evaporation and by reducing the efficiency with which these atmospheric components are scavenged. It is thought likely that the transport of gaseous molecules into and out of the aqueous solution will be impeded by factors of several hundred or more when organic films are present.

  5. Force models for particle-dynamics simulations of granular materials

    SciTech Connect

    Walton, O.R.

    1994-12-01

    Engineering-mechanics contact models are utilized to describe the inelastic, frictional interparticle forces acting in dry granular systems. Simple analyses based on one-dimensional chains are utilized to illustrate wave propagation phenomena in dense and dilute discrete particulates. The variation of restitution coefficient with impact velocity is illustrated for a variety of viscous and hysteretic normal force models. The effects of interparticle friction on material strength in discrete-particle simulations are much closer to measured values than are theories that do not allow article rotations.

  6. Atmospheric amines - Part II. Thermodynamic properties and gas/particle partitioning

    NASA Astrophysics Data System (ADS)

    Ge, Xinlei; Wexler, Anthony S.; Clegg, Simon L.

    2011-01-01

    Amines enter the atmosphere from a wide range of sources, but relatively little is known about their atmospheric behavior, especially their role in gas/particle partitioning. In Part I of this work ( Ge et al., 2011) a total of 154 amines, 32 amino acids and urea were identified as occurring in the atmosphere, based upon a survey of the literature. In this work we compile data for the thermodynamic properties of the amines which control gas/particle partitioning (Henry's Law constant, liquid vapor pressure, acid dissociation constant, activity coefficient and solubility in water), and also estimate the solid/gas dissociation constants of their nitrate and chloride salts. Prediction methods for boiling point, liquid vapor pressure, acid dissociation constant and the solubility of the amines in water are evaluated, and used to estimate values of the equilibrium constants where experimental data are lacking. Partitioning of amines into aqueous aerosols is strongly dependent upon pH and is greatest for acidic aerosols. For several common amines the tendency to partition to the particle phase is similar to or greater than that of ammonia. Our results are presented as tables of values of thermodynamic equilibrium constants, which are also incorporated into the Extended Aerosol Inorganics Model ( E-AIM, http://www.aim.env.uea.ac.uk/aim/aim.php) to enable gas/aerosol partitioning and other calculations to be carried out.

  7. Automated inspection of tubular material based on magnetic particle inspection

    NASA Astrophysics Data System (ADS)

    Mahendra, Adhiguna; Stolz, Christophe; Meriaudeau, Fabrice; Petit, Sebastien; Noel, Alexandre; Degoutin, Fabien

    2012-01-01

    Automatic industrial surface inspection methodology based on Magnetic Particle Inspection is developed from image acquisition to defect classification. First the acquisition system is optimized, then tubular material images are acquired, reconstructed then stored. The characteristics of the crack-like defects with respect to its geometric model and curvature are used as a priori knowledge for mathematical morphology and linear filtering. After the segmentation and binarization of the image, vast amount of defect candidates exist. Finally classification is performed with decision tree learning algorithm due to its robustness and speed. The parameters for mathematical morphology, linear filtering and classification are analyzed and optimized with Design Of Experiments based on Taguchi approach. The most significant parameters obtained may be analyzed and tuned further. Experiments are performed on tubular materials and evaluated by its accuracy and robustness by comparing ground truth and processed images. The result is promising with 97 % True Positive and only 0.01 % False Positive rate on the testing set.

  8. Viscosity of ?-pinene secondary organic material and implications for particle growth and reactivity

    SciTech Connect

    Renbaum-Wolff, Lindsay; Grayson, James W.; Bateman, Adam P.; Kuwata, Mikinori; Sellier, Mathieu; Murray, Benjamin J.; Shilling, John E.; Martin, Scot T.; Bertram, Allan K.

    2013-05-14

    Particles composed of secondary organic material (SOM) are abundant in the lower troposphere and play important roles in climate, air quality, and health. The viscosity of these particles is a fundamental property that is presently poorly quantified for conditions relevant to the lower troposphere. Using two new techniques, namely a bead-mobility technique and a poke-flow technique, in conjunction with simulations of fluid flow, we measure the viscosity of the watersoluble component of SOM produced by ?-pinene ozonolysis. The viscosity is comparable to that of honey at 90% relative humidity (RH), comparable to that of peanut butter at 70% RH and greater than or comparable to that of bitumen for ? 30% RH, implying that the studied SOM ranges from liquid to semisolid/solid at ambient relative humidities. With the Stokes-Einstein relation, the measured viscosities further imply that the growth and evaporation of SOM by the exchange of organic molecules between the gas and condensed phases may be confined to the surface region when RH ? 30%, suggesting the importance of an adsorption-type mechanism for partitioning in this regime. By comparison, for RH ? 70% partitioning of organic molecules may effectively occur by an absorption mechanism throughout the bulk of the particle. Finally, the net uptake rates of semi-reactive atmospheric oxidants such as O3 are expected to decrease by two to five orders of magnitude for a change in RH from 90% to ? 30% RH, with possible implications for the rates of chemical aging of SOM particles in the atmosphere.

  9. Particle-hole pair states of layered materials

    NASA Astrophysics Data System (ADS)

    Lokot, Lyubov E.

    2015-04-01

    In the paper a theoretical study of both the quantized energies of excitonic states and their wave functions in gapped graphene and in monolayer of MoS2 is presented. An integral two-dimensional Schrödinger equation of the electron-hole pairing for particles with electron-hole symmetry of reflection is analytically solved. The solutions of Schrödinger equation in momentum space in gapped graphene and in the direct band monolayer of MoS2 by projection the two-dimensional space of momentum on the three-dimensional sphere are found. We analytically solve an integral two-dimensional Schrödinger equation of the electron-hole pairing for particles with electron-hole symmetry of reflection and with strong spin-orbit coupling. In monolayer of MoS2 as well as in single-layer graphene (SLG) the electron-hole pairing leads to the exciton insulator states. Calculating an integral two-dimensional Schrödinger equation of the electron-hole pairing for bilayer graphene, exciton insulator states with a gap 3 meV are predicted. The particle-hole symmetry of Dirac equation of layered materials allows perfect pairing between electron Fermi sphere and hole Fermi sphere in the valence band and conduction band and hence driving the Cooper instability.

  10. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    SciTech Connect

    farquar, G; Leif, R

    2008-09-12

    Biocompatible polymers with hydrolyzable chemical bonds are being used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres are being produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. The advantages and disadvantages of each method will be presented and discussed in greater detail along with fluorescent and charge properties of the aerosols. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  11. Sulfur-containing particles emitted by concealed sulfide ore deposits: an unknown source of sulfur-containing particles in the atmosphere

    NASA Astrophysics Data System (ADS)

    Cao, J. J.; Li, Y. K.; Jiang, T.; Hu, G.

    2015-06-01

    Sources of sulfur dioxide, sulfates, and organic sulfur compounds, such as fossil fuels, volcanic eruptions, and animal feeding operations, have attracted considerable attention. In this study, we collected particles carried by geogas flows ascending through soil, geogas flows above the soil that had passed through the soil, and geogas flows ascending through deep faults of concealed sulfide ore deposits, and analysed them using transmission electron microscopy. Numerous crystalline and amorphous sulfur-containing particles or particle aggregations were found in the ascending geogas flows. In addition to S, the particles contained O, Ca, K, Mg, Fe, Na, Pb, Hg, Cu, Zn, As, Ti, Sr, Ba, Si, etc. Such particles are usually a few to several hundred nanometres in diameter with either regular or irregular morphology. The sulfur-containing particles originated from deep-seated weathering or faulting products of concealed sulfide ore deposits. The particles suspended in the ascending geogas flow migrated through faults from deep-seated sources to the atmosphere. This is a previously unknown source of the atmospheric particles. This paper reports, for the first time, the emission of sulfur-containing particles into the atmosphere from concealed sulfide ore deposits. The climatic and ecological influences of these sulfur-containing particles and particle aggregations should be assessed.

  12. Atmospheric Solids Analysis Probe Mass Spectrometry: A New Approach for Airborne Particle Analysis

    SciTech Connect

    Bruns, Emily A.; Perraud, Veronique M.; Greaves, John; Finlayson-Pitts, Barbara J.

    2010-07-15

    Secondary organic aerosols (SOA) formed in the atmosphere from the condensation of semivolatile oxidation products are a significant component of airborne particles which have deleterious effects on health, visibility, and climate. In this study, atmospheric solids analysis probe mass spectrometry (ASAP-MS) is applied for the first time to the identification of organics in particles from laboratory systems as well as from ambient air. SOA were generated in the laboratory from the ozonolysis of r-pinene and isoprene, as well as from NO3 oxidation of r-pinene, and ambient air was sampled at forested and suburban sites. Particles were collected by impaction on ZnSe disks, analyzed by Fourier transform-infrared spectroscopy (FT-IR) and then transferred to an ASAP-MS probe for further analysis. ASAP-MS data for the laboratory-generated samples show peaks from wellknown products of these reactions, and higher molecular weight oligomers are present in both laboratory and ambient samples. Oligomeric products are shown to be present in the NO3 reaction products for the first time. A major advantage of this technique is that minimal sample preparation is required, and complementary information from nondestructive techniques such as FT-IR can be obtained on the same samples. In addition, a dedicated instrument is not required for particle analysis. This work establishes that ASAP-MS will be useful for identification of organic components of SOA in a variety of field and laboratory studies.

  13. The transmission of differing energy beta particles through various materials

    SciTech Connect

    Quayle, D.R.

    1996-04-01

    The transmission of beta particles is frequently calculated in the same fashion as that of gamma rays, where the mass attenuation coefficient is defined by the slope of the exponential function. Numerous authors have used this approximation including Evans (1955), Loevinger (1952), and Chabot et. al. (1988). Recent work by McCarthy et. al. (1995) indicated that the exponential function seemed to fit well over a particular region of the transmission curve. Upon further investigation, the author decided to verify McCarthy`s results by the use of different absorber materials and attempt to reproduce the experiments. A theoretical method will be used to estimate the transmission of the beta particles through the three absorbers, aluminum, zirconium, and iron. An alternate Monte Carlo code, the Electron Gamma Shower version 4 code (EGS4) will also be used to verify that the experiment is approximating a pencil beam of beta particles. Although these two methods offer a good cross check for the experimental data, they pose a conflict in regards to the type of beam that is to be generated. The experimental lab setup uses a collimated beam of electrons that will impinge upon the absorber, while the codes are written using a pencil beam. A minor discrepancy is expected to be observed in the experimental results and is currently under investigation by McCarthy. The results of this project supported the theory that the beta mass attenuation coefficient was accurately represented by the slope of an exponential function, but only for that particular region of the transmission curve that has a minimal absorber thickness. By fitting the data beyond 50% of the beta particle range this theory does not hold true. The theory generated by McCarthy (1995) and the EGS4 Monte Carlo code indicated that the transmission curve for a pencil beam was not accurately represented by an exponential function. The results of this experiment appeared to provide additional support to this assumption.

  14. Influence of Particle Phase Morphology on the Hygroscopic Behavior of Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Hodas, N.; Zuend, A.; Flagan, R. C.; Seinfeld, J.

    2014-12-01

    While current models generally treat organic and mixed organic-inorganic aerosol particles as well-mixed liquids, these particles can exist in multiple phase states depending on their chemical composition and on ambient conditions such as relative humidity (RH). For example, multi-component particles can undergo phase separations in which an inorganic-electrolyte-rich phase and an organic-rich phase coexist within one particle. Organic aerosols have been shown to exist in an amorphous, highly viscous semi-solid state under atmospherically relevant conditions. Hygroscopic growth factors (GFs) of ten laboratory-generated, organic-inorganic aerosol systems with phase morphologies ranging from well-mixed liquids, to phase-separated particles, to viscous semi-solids were measured with the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe at RH values ranging from 30 - 90%. Measured GFs were compared to water-uptake calculations in which it was assumed that particles could be represented as thermodynamically ideal, well-mixed liquids, as well as those predicted by the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. Both ideal and AIOMFAC-predicted GFs were in good agreement with experimental GFs for aerosol systems that exist as well-mixed liquids across the range of RHs tested; however, substantial disagreement between experimental and ideal GFs was observed for phase-separated particles. This disagreement was greatest at low to moderate RHs, whereas experimental GFs approached the ideal curve at high RH as phase-separated particles merged to a single phase with increased water content. AIOMFAC, which offers the ability to predict liquid-liquid and liquid-solid phase separations within a thermodynamic equilibrium computation, was within 10% of experimental GFs at all RHs for all aerosol systems. The assumption that water uptake is driven by ideal, equilibrium partitioning leads to errors in calculated particle size and refractive index and has implications for predicted aerosol scattering efficiencies and radiative properties.

  15. Influence of radioactivity on surface charging and aggregation kinetics of particles in the atmosphere.

    PubMed

    Kim, Yong-Ha; Yiacoumi, Sotira; Lee, Ida; McFarlane, Joanna; Tsouris, Costas

    2014-01-01

    Radioactivity can influence surface interactions, but its effects on particle aggregation kinetics have not been included in transport modeling of radioactive particles. In this research, experimental and theoretical studies have been performed to investigate the influence of radioactivity on surface charging and aggregation kinetics of radioactive particles in the atmosphere. Radioactivity-induced charging mechanisms have been investigated at the microscopic level, and heterogeneous surface potential caused by radioactivity is reported. The radioactivity-induced surface charging is highly influenced by several parameters, such as rate and type of radioactive decay. A population balance model, including interparticle forces, has been employed to study the effects of radioactivity on particle aggregation kinetics in air. It has been found that radioactivity can hinder aggregation of particles because of similar surface charging caused by the decay process. Experimental and theoretical studies provide useful insights into the understanding of transport characteristics of radioactive particles emitted from severe nuclear events, such as the recent accident of Fukushima or deliberate explosions of radiological devices. PMID:24308778

  16. In situ measurements of gas/particle-phase transitions for atmospheric semivolatile organic compounds.

    PubMed

    Williams, Brent J; Goldstein, Allen H; Kreisberg, Nathan M; Hering, Susanne V

    2010-04-13

    An understanding of the gas/particle-phase partitioning of semivolatile compounds is critical in determining atmospheric aerosol formation processes and growth rates, which in turn affect global climate and human health. The Study of Organic Aerosol at Riverside 2005 campaign was performed to gain a better understanding of the factors responsible for aerosol formation and growth in Riverside, CA, a region with high concentrations of secondary organic aerosol formed through the phase transfer of low-volatility reaction products from the oxidation of precursor gases. We explore the ability of the thermal desorption aerosol gas chromatograph (TAG) to measure gas-to-particle-phase transitioning for several organic compound classes (polar and nonpolar) found in the ambient Riverside atmosphere by using in situ observations of several hundred semivolatile organic compounds. Here we compare TAG measurements to modeled partitioning of select semivolatile organic compounds. Although TAG was not designed to quantify the vapor phase of semivolatile organics, TAG measurements do distinguish when specific compounds are dominantly in the vapor phase, are dominantly in the particle phase, or have both phases present. Because the TAG data are both speciated and time-resolved, this distinction is sufficient to see the transition from vapor to particle phase as a function of carbon number and compound class. Laboratory studies typically measure the phase partitioning of semivolatile organic compounds by using pure compounds or simple mixtures, whereas hourly TAG phase partitioning measurements can be made in the complex mixture of thousands of polar/nonpolar and organic/inorganic compounds found in the atmosphere. PMID:20142511

  17. Characterization of Complex Organic Compounds Formed in Simulated Planetary Atmospheres by the Action of High Energy Particles

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kensei; Kaneko, Takeo; Saito, Takeshi

    1999-01-01

    A wide variety of organic compounds, which are not simple organics but also complex organics, have been found in planets and comets. We reported that complex organics was formed in simulated planetary atmospheres by the action of high energy particles. Here we characterized the experimental products by using chromatographic and mass spectrometric techniques. A gaseous mixture of CO, N2 and H2O was irradiated with high energy protons (major components of cosmic rays). Water-soluble non-volatile substances, which gave amino acids after acid-hydrolysis, were characterized by HPLC and mass spectrometry. Major part of the products were complex compounds with molecular weight of several hundreds. Amino acid precursors were produced even when no water was incorporated with the starting materials. It was suggested that complex molecules including amino acid precursors were formed not in solution from simple molecules like HCN, but directly in gaseous phase

  18. Dysprosium Doped Dielectric Materials for Sintering in Reducing Atmospheres

    Microsoft Academic Search

    Wen-Hsi Lee; W. A. Groen; Herbert Schreinemacher; Detlev Hennings

    2000-01-01

    Substitution of Dy rare earth ions was studied in Ba(Ti,Zr)O3 dielectric materials, using thermogravimetry, X-ray diffraction and dielectric measurements. Dy3+ ions enter both the A- and the B-sites of the perovskite structure, however, the solubility on B-sites is up to 9 mol %, whereas it is only 2.5 mol% on A-sites. Dy can be easily shifted from A- to B-sites

  19. Biological contribution to ice nucleation active particles in clouds at the puy de Dôme atmospheric station, France

    NASA Astrophysics Data System (ADS)

    Amato, Pierre; Joly, Muriel; Deguillaume, Laurent; Delort, Anne-Marie

    2015-04-01

    The distribution, abundance and nature of ice nucleation active particles in the atmosphere are major sources of uncertainty in the prediction of cloud coverage, precipitation patterns and climate. Some biological ice nuclei (IN) induce freezing at temperatures at which most other atmospheric particles exhibit no detectable activity (> -10°C), but their actual contribution to the pool of IN in clouds remains poorly known. In order to help elucidating this, cloud water was collected aseptically from the summit of Puy de Dome (1465m a.s.l., France) within contrasted meteorological and physico-chemical situations. Total and biological (i.e. heat-sensitive) IN were quantified by droplet-freezing assay between -5°C and -14°C. We observed that freezing was systematically induced by biological material, between -6°C and -8°C in 92{%} of the samples. Its removal by heat treatment consistently led to a decrease of the onset freezing temperature, by 3°C or more in most samples. At -10°C, 0 to 220 biological IN mL-1 of cloud water were measured (i.e. 0 to 22 m-3 of cloud air), and these represented 65{%} to 100{%} of the total IN. Based on back-trajectories and on physico-chemical analyses, the high variability observed resulted probably from a source effect, with IN originating mostly from continental sources. Bacteria concentration in the air at altitude relevant for clouds typically ranges from ˜102 to ˜105 cells m-3. Assuming that biological IN measured in cloud water samples at -8°C were all bacteria, ice nucleation active bacteria represented at maximum 0.6{%} of the total bacteria cells present (3.1{%} at -12°C). These results should help elucidating the role of biological and bacterial IN on cloud microphysics and their impact on precipitation at local scale. References: Joly, M., Amato, P., Deguillaume, L., Monier, M., Hoose, C., and Delort A-M (2014). Quantification of ice nuclei active at near 0°C temperatures in low altitude clouds at the puy de Dome atmospheric station. Atmospheric Chemistry and Physics 14, 8185-8195. Joly, M., Attard, E., Sancelme, M., Deguillaume, L., Guilbaud, C., Morris, C., Amato, P. and Delort A-M (2013). Ice nucleation activity of bacteria isolated from cloud water. Atmospheric Environment 70, 392-400.

  20. Relationship Between Particle and Plasma Properties and Coating Characteristics of Samaria-Doped Ceria Prepared by Atmospheric Plasma Spraying for Use in Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Cuglietta, Mark; Kesler, Olivera

    2012-06-01

    Samaria-doped ceria (SDC) has become a promising material for the fabrication of high-performance, intermediate-temperature solid oxide fuel cells (SOFCs). In this study, the in-flight characteristics, such as particle velocity and surface temperature, of spray-dried SDC agglomerates were measured and correlated to the resulting microstructures of SDC coatings fabricated using atmospheric plasma spraying, a manufacturing technique with the capability of producing full cells in minutes. Plasmas containing argon, nitrogen and hydrogen led to particle surface temperatures higher than those in plasmas containing only argon and nitrogen. A threshold temperature for the successful deposition of SDC on porous stainless steel substrates was calculated to be 2570 °C. Coating porosity was found to be linked to average particle temperature, suggesting that plasma conditions leading to lower particle temperatures may be most suitable for fabricating porous SOFC electrode layers.

  1. Particle excitation, airglow and H2 vibrational disequilibrium in the atmosphere of Jupiter

    NASA Technical Reports Server (NTRS)

    Shemansky, D. E.

    1984-01-01

    The extreme ultraviolet EUV emission produced by particle excitation of the hydrogen atmospheres of Jupiter and Saturn is examined using model calculations to determine the nature of the energy deposition process and the effect of such processes on atmospheric structure. Tasks ranging from examination of phenomenologically related processes on Saturn and Titan to analysis of experimental laboratory data required to allow accurate modeling of emissions from hydrogenic atmospheres are investigated. An explanation of the hydrogen H Ly(alpha) bulge in Jupiter's emission from the equatorial region is presented. It is proposed that Saturn, rather then Titan is the major source of the extended hydrogen cloud. The atomic hydrogen detected at the rings of Saturn may originate predominantly from the same source. A cross calibration is obtained between the Pioneer 10 EUV photometer and the Voyager EUV spectrometers, thus providing a direct measure of the temporal morphology of Jupiter between a minimum and a maximum in solar activity. Atomic and molecular data required for the research program are analyzed. An extrapolation of conditions in the upper atmospheres of Jupiter and Saturn produces a predicted condition at Uranus in terms of excitation and hydrogen escape rates that may be observed at Voyager-Uranus encounter.

  2. Particle lifting at the soil-air interface by atmospheric pressure excursions in dust devils

    Microsoft Academic Search

    Matthew Balme; Axel Hagermann

    2006-01-01

    Dust devils, small-scale convective vortices found on Earth and on Mars, can transfer substantial quantities of dust from the ground into the atmosphere. It has been proposed that the low-pressure region found at the center of dust devil vortices provides a lift (the `DeltaP' effect) that `sucks up' material from the surface. Two simple models are compared to investigate the

  3. Atmospheric number size distributions of soot particles and estimation of emission factors

    NASA Astrophysics Data System (ADS)

    Rose, D.; Wehner, B.; Ketzel, M.; Engler, C.; Voigtländer, J.; Tuch, T.; Wiedensohler, A.

    2005-10-01

    Number fractions of externally mixed particles of four different sizes (30, 50, 80, and 150 nm in diameter) were measured using a Volatility Tandem DMA. The system was operated in a street canyon (Eisenbahnstrasse, EI) and at an urban background site (Institute for Tropospheric Research, IfT), both in the city of Leipzig, Germany as well as at a rural site (Melpitz (ME), a village near Leipzig). Intensive campaigns of 3-5 weeks each took place in summer 2003 as well as in winter 2003/2004. The data set thus obtained provides mean number fractions of externally mixed soot particles of atmospheric aerosols in differently polluted areas and different seasons (e.g. at 80 nm on working days, 60% (EI), 22% (IfT), and 6% (ME) in summer and 26% (IfT), and 13% (ME) in winter). Furthermore, a new method is used to calculate the size distribution of these externally mixed soot particles from parallel number size distribution measurements. A decrease of the externally mixed soot fraction with decreasing urbanity and a diurnal variation linked to the daily traffic changes demonstrate, that the traffic emissions have a significant impact on the soot fraction in urban areas. This influence becomes less in rural areas, due to atmospheric mixing and transformation processes. For estimating the source strength of soot particles emitted by vehicles (veh), soot particle emission factors were calculated using the Operational Street Pollution Model (OSPM). The emission factor for an average vehicle was found to be (1.5±0.4)·1014 #/(km·veh). The separation of the emission factor into passenger cars ((5.8±2)·1013 #/(km·veh)) and trucks ((2.5±0.9)·1015 #/(km·veh)) yielded in a 40-times higher emission factor for trucks compared to passenger cars.

  4. Atmospheric number size distributions of soot particles and estimation of emission factors

    NASA Astrophysics Data System (ADS)

    Rose, D.; Wehner, B.; Ketzel, M.; Engler, C.; Voigtländer, J.; Tuch, T.; Wiedensohler, A.

    2006-03-01

    Number fractions of externally mixed particles of four different sizes (30, 50, 80, and 150 nm in diameter) were measured using a Volatility Tandem DMA. The system was operated in a street canyon (Eisenbahnstrasse, EI) and at an urban background site (Institute for Tropospheric Research, IfT), both in the city of Leipzig, Germany as well as at a rural site (Melpitz (ME), a village near Leipzig). Intensive campaigns of 3-5 weeks each took place in summer 2003 as well as in winter 2003/04. The data set thus obtained provides mean number fractions of externally mixed soot particles of atmospheric aerosols in differently polluted areas and different seasons (e.g. at 80 nm on working days, 60% (EI), 22% (IfT), and 6% (ME) in summer and 26% (IfT), and 13% (ME) in winter). Furthermore, a new method is used to calculate the size distribution of these externally mixed soot particles from parallel number size distribution measurements. A decrease of the externally mixed soot fraction with decreasing urbanity and a diurnal variation linked to the daily traffic changes demonstrate, that the traffic emissions have a significant impact on the soot fraction in urban areas. This influence becomes less in rural areas, due to atmospheric mixing and transformation processes. For estimating the source strength of soot particles emitted by vehicles (veh), soot particle emission factors were calculated using the Operational Street Pollution Model (OSPM). The emission factor for an average vehicle was found to be (1.5±0.4)·1014 #(km·veh). The separation of the emission factor into passenger cars ((5.8±2)·1013} #(km·veh)) and trucks ((2.5±0.9)·1015 #(km·veh)) yielded in a 40-times higher emission factor for trucks compared to passenger cars.

  5. Lung cancer mortality and exposure to atmospheric aerosol particles in Guangzhou, China

    NASA Astrophysics Data System (ADS)

    Tie, Xuexi; Wu, Dui; Brasseur, Guy

    In recent years, China and other emerging countries have been experiencing severe air pollution problems with high concentrations of atmospheric aerosol particles. Satellite measurements indicate that the aerosol loading of the atmosphere in highly populated regions of China is about 10 times higher than, for example, in Europe and in the Eastern United States. The exposure to extremely high aerosol concentrations might lead to important human health effects, including respiratory and cardiovascular diseases as well as lung cancers. Here, we analyze 52-year historical surface measurements of haze data in the Chinese city of Guangzhou, and show that the dramatic increase in the occurrence of air pollution events between 1954 and 2006 has been followed by a large enhancement in the incidence of lung cancer.

  6. Monte-Carlo calculations of particle fluences and neutron effective dose rates in the atmosphere.

    PubMed

    Matthiä, Daniel; Sihver, Lembit; Meier, Matthias

    2008-01-01

    Monitoring of radiation exposure of aircrew is a legal requirement for many airlines in the EU and a challenging task in dosimetry. Monte-Carlo simulations of cosmic particles in the atmosphere can contribute to the understanding of the corresponding radiation field. Calculations of secondary neutron fluences in the atmosphere produced by galactic cosmic rays together with the resulting neutron-effective dose rates are shown in this paper and compared with results from the AIR project. The PLANETOCOSMICS package based on GEANT4 and two models for the local interstellar spectra of galactic cosmic rays have been used for the calculations. Furthermore, secondary muon fluences have been computed and are compared with CAPRICE measurements. PMID:18448435

  7. Thermal stability of beam sensitive atmospheric aerosol particles in electron probe microanalysis at liquid nitrogen temperature

    NASA Astrophysics Data System (ADS)

    Worobiec, Anna; de Hoog, Johan; Osán, János; Szalóki, Imre; Ro, Chul-Un; Van Grieken, René

    2003-03-01

    Thin-window electron probe X-ray microanalysis offers new analytical possibilities for low- Z detection (i.e. elements with low atomic number; such as C, N and O). However, the quantitative analysis of individual particles raises some practical questions concerning the technique. From the analytical point of view, beam damage is one of the most important problems due to its big impact on the analysis of individual atmospheric particles. The dependence of the beam-damage effect on the type of collection substrate was studied using standard aerosol particles. Different metallic substrates were rigorously tested in relation to the beam damage effects to different kinds of beam sensitive particles. Ammonium sulfate, ammonium nitrate, sodium nitrate as well as sulfuric acid droplets were analyzed using a liquid nitrogen cooled sample stage on different metallic substrates such as Be, Al, Si and Ag. The obtained results confirm that the use of Be as a collection surface offers some advantages in order to minimize the damage to beam sensitive particles, as suggested in earlier research.

  8. Shape of atmospheric mineral particles collected in three Chinese arid-regions

    NASA Astrophysics Data System (ADS)

    Okada, Kikuo; Heintzenberg, Jost; Kai, Kenji; Qin, Yu

    The shape of atmospheric mineral particles of 0.1-6 µm radius was studied by electron microscopy applied to the samples collected in three arid regions in China (Qira in the Taklamakan Desert, Zhangye near the southern border of the Badain-Jaran Desert and Hohhot in northern China). In all three regions, the mineral particles showed irregular shapes with a median aspect ratio b/a (ratio of the longest dimension b to the orthogonal width a) of 1.4. Although the aspect ratio exhibited no clear size dependence, the circularity factor (4?S/l² S is surface area and l is periphery length) tended to decrease with increasing radius, suggesting the presence of aggregated mineral particles at larger sizes. The ratio of particle height-to-width h/a was also evaluated by measuring the shadow length. The median ratio h/a was 0.49 in Hohhot, 0.29 in Zhangye and 0.23 in Qira. Analytical functions were fitted to the grand total of the frequency distributions of aspect ratios, height-to-width ratios and circularity factors allowing parametric calculations of radiative effects and calculations of optical and sedimentation behavior of mineral particles.

  9. In Situ Single Particle Measurement of Atmospheric Aging of Carbonaceous Aerosols During CARES

    NASA Astrophysics Data System (ADS)

    Cahill, J. F.; Suski, K.; Hubbe, J.; Shilling, J.; Zaveri, R. A.; Springston, S. R.; Prather, K. A.

    2011-12-01

    Atmospheric aging of aerosols through photochemistry, heterogeneous reactions and aqueous processing can change their physical and chemical properties, impacting their gas uptake, radiative forcing, and activation of cloud nuclei. Understanding the timescale and magnitude of this aging process is essential for accurate aerosol-climate modeling and predictions. An aircraft aerosol time-of-flight mass spectrometer (A-ATOFMS) measured single particle mixing state during the Carbonaceous Aerosols and Radiative Effects Study (CARES) in the summer of 2010 over Sacramento, CA. On 6/23/10, flights in the morning and afternoon performed pseudo-Lagrangian sampling of the Sacramento urban plume. Carbonaceous particles from these flights were classified into 'aged' and 'fresh' classes based on their mixing state, with aged particles having more secondary species, such as nitrate and sulfate. In the morning flight, a clear decreasing trend in the ratio of fresh/aged particle types was seen as the flight progressed, whereas in the afternoon flight, the ratio was essentially constant. These data show that in the morning carbonaceous aerosols can become heavily oxidized in a few hours. Further analysis of particle mixing state and the timescale of carbonaceous aerosol aging will be presented

  10. The Effect of Particle Size on Iron Solubility in Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Marcotte, A. R.; Majestic, B. J.; Anbar, A. D.; Herckes, P.

    2012-12-01

    The long range transport of mineral dust aerosols, which contain approximately 3% iron by mass, results in an estimated 14-16 Tg of iron deposited into the oceans annually; however, only a small percentage of the deposited iron is soluble. In high-nutrient, low chlorophyll ocean regions iron solubility may limit phytoplankton primary productivity. Although the atmospheric transport processes of mineral dust aerosols have been well studied, the role of particle size has been given little attention. In this work, the effect of particle size on iron solubility in atmospheric aerosols is examined. Iron-containing minerals (illite, kaolinite, magnetite, goethite, red hematite, black hematite, and quartz) were separated into five size fractions (10-2.5, 2.5-1, 1-0.5, 0.5-0.25, and <0.25?m) and extracted into buffer solutions simulating environments in the transport of aerosol particles for 150 minutes. Particle size was confirmed by scanning electron microscopy (SEM). Soluble iron content of the extracted mineral solutions was determined by inductively coupled plasma-mass spectrometry (ICP-MS). Extracted mineral solutions were also analyzed for Fe(II) and Fe(III) content using a ferrozine/UV-VIS method. Preliminary results show that differences in solution composition are more important than differences in size. When extracted into acetate and cloudwater buffers (pH 4.25-4.3), < 0.3% of the Fe in iron oxides (hematite, magnetite, and goethite) is transferred to solution as compared to ~0.1-35% for clays (kaolinite and illite). When extracted into a marine aerosol solution (pH 1.7), the percentage of Fe of the iron oxides and clays transferred to solution increases to approximately 0.5-3% and 5-70%, respectively. However, there is a trend of increased %Fe in the minerals transferred to solution in the largest and smallest size fractions (~0.01-0.3% and ~0.5-35% for iron oxides and clays, respectively), and decreased %Fe in the minerals transferred to solution in the mid-range size fraction (~0.01-0.08% and ~0.1-1% for iron oxides and clays, respectively) when extracted into the acetate and cloudwater buffers. When extracted into the marine aerosol solution the %Fe in the minerals transferred to solution increases with decreasing particle size (from ~0.7% to ~2% and ~10 to 70% in iron oxides and clays, respectively). By examining the role of particle size, this work will provide a more complete understanding of iron dissolution during atmospheric transport of mineral dust aerosols.

  11. Atmosphere

    NSDL National Science Digital Library

    University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

    2003-01-01

    What is this atmosphere that surrounds the Earth? This instructional tutorial, part of an interactive laboratory series for grades 8-12, introduces students to the structure, effects, and components of the atmosphere. Here students investigate the composition of the atmosphere; effects of temperature, pressure, and ozone; the greenhouse effect; and how Earth compares with other planets. Interactive activities present students with opportunities to explore ideas and answer questions about the atmosphere, including its structure, the making of ozone, rocket launching, and measuring the atmosphere. Pop-up boxes provide additional information on topics such as dust, rain, and atmospheric composition. Students complete a final written review of six questions about the atmosphere. Copyright 2005 Eisenhower National Clearinghouse

  12. Experimental studies on particle impaction and bounce: effects of substrate design and material

    Microsoft Academic Search

    Mingchih Chang; Seongheon Kim; Constantinos Sioutas

    1999-01-01

    This paper presents an experimental investigation of the effects of impaction substrate designs and material in reducing particle bounce and reentrainment. Particle collection without coating by using combinations of different impaction substrate designs and surface materials was conducted using a personal particle sampler (PPS) developed by the University of Southern California. The PPS operates at flow rate of 4 lmin-1

  13. Impacts of the January 2005 solar particle events on middle atmospheric chlorine species

    NASA Astrophysics Data System (ADS)

    Winkler, Holger; Sinnhuber, Miriam; Notholt, Justus; Maik Wissing, Jan; Kallenrode, May-Britt; Santee, Michelle

    It is well established that solar particle events (SPEs) are sources of significant chemical dis-turbances in the Earth's polar atmosphere. The observed SPE effects on nitrogen, hydrogen and oxygen compounds have been investigated in some detail in recent years, and they can be reproduced by atmospheric models using basic parametrizations for NOx and HOx produc-tion as a funtion of the particle impact ionisation. However, there are considerable differences between model predictions and measurements concerning several other trace gases including chlorine species. Two major SPEs occurred on January 17, and January 20, 2005. The latter had an exceptionally hard energy spectrum which caused maximum particle impact ionization at stratospheric altitudes. The Microwave Limb Sounder (MLS) instrument on-board the Aura satellite has measured a short-term decrease of HCl in the northern polar region corresponding to January 2005 SPEs. The peak HCl depletion is ˜300 ppt at 35-40 km. This is comparable to the depletion of messopheric HCl observed by the HALOE instrument during the July 2000 SPE. We will present simulation results of the University of Bremen Ion Chemistry (UBIC) model for the SPEs in January 2005 focusing on chlorine species. The simulations indicate that the observed short-term decrease of middle atmospheric HCl is due to a conversion into active chlorine species such as Cl, ClO and HOCl. The magnitude of the observed HCl loss can only be reproduced if reactions of negative chlorine species and the production of O(1 D) from the reaction N(2 D) + O2 are taken into account. The model results will be compared to MLS/Aura data of HCl, HOCl and ClO. Additionally, the impacts of the observed chlorine activation, e.g. on ozone, will be assessed.

  14. Gas\\/particle partitioning of currently used pesticides in the atmosphere of Strasbourg (France)

    Microsoft Academic Search

    Claude Schummer; Elodie Mothiron; Brice M. R. Appenzeller; Robert Wennig; Maurice Millet

    2010-01-01

    Atmospheric particle (P) and gas (G) phase samples have been collected in Strasbourg (Northeast of France) using a high-volume\\u000a sampler equipped with a filter-XAD-2 resin plug between April 17 and May 29, 2007. Seventy-one currently used pesticides were\\u000a monitored in these samples, and 38 of them were detected at concentrations ranging from 0.07 ng\\/m3 for fenarimol to 40.30 ng\\/m3 for deltamethrin in

  15. Future monitoring of charged particle energy deposition into the upper atmosphere and comments on possible relationships between atmospheric phenomena and solar and/or geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Williams, D. J.; Grubb, R. N.; Evans, D. S.; Sauer, H. H.

    1974-01-01

    The charged particle observations proposed for the new low altitude weather satellites, TIROS-N, are described that will provide the capability of routine monitoring of the instantaneous total energy deposition into the upper atmosphere by the precipitation of charged particles from higher altitudes. Estimates are given to assess the potential importance of this type of energy deposition. Discussion and examples are presented illustrating the importance in distinguishing between solar and geomagnetic activity as possible causative sources.

  16. Influence of humidity, sunlight, and temperature on the daytime decay of polyaromatic hydrocarbons on atmospheric soot particles

    Microsoft Academic Search

    Richard M. Kamens; Zhishi Guo; J. N. Fuicher; Douglas A. Bell

    1988-01-01

    In this paper we have attempted to quantify the loss of polyaromatic hydrocarbons (PAH) on atmospheric soot particles with respect to the effects of humidity, solar radiation, and temperature. Dilute residential wood smoke and internal gasoline combustion emissions were individually aged in the presence of natural sunlight in 25-m³ outdoor Teflon film chambers. Soot particles were collected on filters and

  17. On the gas-particle partitioning of soluble organic aerosol in two urban atmospheres with contrasting emissions

    E-print Network

    Jimenez, Jose-Luis

    On the gas-particle partitioning of soluble organic aerosol in two urban atmospheres; published 12 September 2012. [1] The partitioning of semi-volatile compounds between the gas and particle. Here we investigate the partitioning of water-soluble organic carbon (WSOC) and the formation of SOA

  18. Middle atmospheric ion chemistry during energetic particle events, and impacts on the neutral chemistry

    NASA Astrophysics Data System (ADS)

    Sinnhuber, M.; Winkler, H.; Wieters, N.; Kazeminejad, S.; Wissing, J. M.; Kallenrode, M.-B.; Stiller, G. P.; von Clarmann, T.

    2009-04-01

    It is well established that solar proton events (SPEs) are sources of distinct chemical disturbances in the Earth's polar atmosphere. While the observed SPE caused production of NOx, and the subsequent destruction of ozone can be reproduces quite well by atmospheric models using basic parametrizations for NOx and HOx release as a function of the particle impact ionisation rate, there are significant differences between measurements and model predictions concerning several other chemical compounds. For instance, during the October 2003 SPE, measurements of a number of species were obtained from the MIPAS instrument on-board the ENVISAT satellite. These measurements show significant enhancements of HNO3 and N2O5 as well as an increase of several chlorine species, i.e., ClO, HOCl and ClONO2. Atmospheric models cannot reproduce these chemical effects if only production of NOx and HOx is considered. The impact of positive and negative ion chemistry on the neutral composition of the middle atmosphere is investigated combining model results from the University of Bremen Ion Chemistry model UBIC with different neutral stratosphere-mesosphere models, particularly the new Bremen three-dimensional Chemistry and Transport model of the middle atmosphere. Focus of the investigation will be the impact of negative ion chemistry on the activation of chlorine radicals, and on the partitioning of NOy species. Model results will be compared to measurement data of different satellite instruments (HALOE, MIPAS, MLS) for several large SPEs (e.g., the July 2000, Oct/Nov 2003, and January 2005 events) to show that the observed chlorine activation and the increase of HNO3 can be reproduced much better if full negative ion chemistry is considered additionally to the NOx and HOx production.

  19. Exploring Atmospheric Aerosol Chemistry with Advanced High-Resolution Mass Spectrometry and Particle Imaging Methods

    NASA Astrophysics Data System (ADS)

    Nizkorodov, S.

    2014-12-01

    Physical and chemical complexity of atmospheric aerosols presents significant challenges both to experimentalists working on aerosol characterization and to modelers trying to parameterize critical aerosol properties. Multi-modal approaches that combine state-of-the-art experimental, theoretical, and modeling methods are becoming increasingly important in aerosol research. This presentation will discuss recent applications of unique high-resolution mass spectrometry and particle imaging tools developed at two Department of Energy's user facilities, the Environmental Molecular Science Laboratory (EMSL) and Advanced Light Source (ALS), to studies of molecular composition, photochemical aging, and properties of laboratory-generated and field aerosols. Specifically, this presentation will attempt to address the following questions: (a) how do NO2, SO2, and NH3 affect molecular level composition of anthropogenic aerosols?; (b) what factors determine viscosity/surface tension of organic aerosol particles?; (c) how does photolysis affect molecular composition and optical properties of organic aerosols?

  20. Ideas and perspectives: on the emission of amines from terrestrial vegetation in the context of new atmospheric particle formation

    NASA Astrophysics Data System (ADS)

    Sintermann, J.; Neftel, A.

    2015-06-01

    In this article we summarise recent science which shows how airborne amines, specifically methylamines (MAs), play a key role in new atmospheric particle formation (NPF) by stabilising small molecule clusters. Agricultural emissions are assumed to constitute the most important MA source, but given the short atmospheric residence time of MAs, they can hardly have a direct impact on NPF events observed in remote regions. This leads us to the presentation of existing knowledge focussing on natural vegetation-related MA sources. High MA contents as well as emissions by plants was already described in the 19th century. Strong MA emissions predominantly occur during flowering as part of a pollination strategy. The behaviour is species-specific, but examples of such species are common and widespread. In addition, vegetative plant tissue exhibiting high amounts of MAs might potentially lead to significant emissions. The decomposition of organic material constitutes another, potentially ubiquitous, source of airborne MAs. These mechanisms would provide sources, which could be crucial for the amine's role in NPF, especially in remote regions. Knowledge about vegetation-related amine emissions is, however, very limited, and thus it is also an open question how global change and the intensified cycling of reactive nitrogen over the last 200 years have altered amine emissions from vegetation with a corresponding effect on NPF.

  1. Special Issue for the 9th International Conference on Carbonaceous Particles in the Atmosphere

    SciTech Connect

    Strawa, A.W.; Kirchstetter, T.W.; Puxbaum, H.

    2009-12-11

    Carbonaceous particles are a minor constituent of the atmosphere but have a profound effect on air quality, human health, visibility and climate. The importance of carbonaceous particles has been increasingly recognized and become a mainstream topic at numerous conferences. Such was not the case in 1978, when the 1st International Conference on Carbonaceous Particles in the Atmosphere (ICCPA), or ''Carbon Conference'' as it is widely known, was introduced as a new forum to bring together scientists who were just beginning to reveal the importance and complexity of carbonaceous particles in the environment. Table 1 lists the conference dates, venues in the series as well as the proceedings, and special issues resulting form the meetings. Penner and Novakov (Penner and Novakov, 1996) provide an excellent historical perspective to the early ICCPA Conferences. Thirty years later, the ninth in this conference series was held at its inception site, Berkeley, California, attended by 160 scientists from 31 countries, and featuring both new and old themes in 49 oral and 83 poster presentations. Topics covered such areas as historical trends in black carbon aerosol, ambient concentrations, analytic techniques, secondary aerosol formation, biogenic, biomass, and HULIS1 characterization, optical properties, and regional and global climate effects. The conference website, http://iccpa.lbl.gov/, holds the agenda, as well as many presentations, for the 9th ICCPA. The 10th ICCPA is tentatively scheduled for 2011 in Vienna, Austria. The papers in this issue are representative of several of the themes discussed in the conference. Ban-Weiss et al., (Ban-Weiss et al., accepted) measured the abundance of ultrafine particles in a traffic tunnel and found that heavy duty diesel trucks emit at least an order of magnitude more ultrafine particles than light duty gas-powered vehicles per unit of fuel burned. Understanding of this issue is important as ultrafine particles have been shown to adversely affect human health (Lighty et al., 2000; Pope and Dockery, 2006). Gan et al. (Gan et al., accepted) examined the indoor air quality aboard submarines and found that the diesel particulate matter concentrations exceeded the EPA 24 hour standard. Claeys et al. (Claeys et al., accepted) studied the importance and sources of secondary organic aerosol (SOA) in remote marine environment during a period of high biological activity. Methanesulphonate was the major SOA compound detected and there was no evidence for SOA from isoprene. The optical properties of gasoline and diesel vehicle particulate emissions and their relative contribution to radiative forcing was studied by Strawa et al. (Strawa et al., accepted).

  2. Modeling the possible role of iodine oxides in atmospheric new particle formation

    NASA Astrophysics Data System (ADS)

    Pechtl, S.; Lovejoy, E. R.; Burkholder, J. B.; von Glasow, R.

    2006-02-01

    We studied the possible role of iodine oxides in atmospheric new particle formation with the one-dimensional marine boundary layer model MISTRA, which includes chemistry in the gas and aerosol phase as well as aerosol microphysics. The chemical reaction set focuses on halogen (Cl-Br-I) chemistry. We included a two-step nucleation parameterization, where in the first step, the "real" nucleation process is parameterized, i.e., the formation of cluster-sized nuclei via homogeneous condensation of gases. We considered both ternary sulfuric acid-ammonia-water nucleation and homomolecular homogeneous OIO nucleation. For the latter, we derived a parameterization based on combined laboratory-model studies. The second step of the nucleation parameterization treats the "apparent" nucleation rate, i.e., the growth of clusters into the model's lowest size bin by condensable vapors such as OIO. We compared different scenarios for a clean marine versus a polluted continental background atmosphere. In every scenario, we assumed the air to move, independent of its origin, first over a coastal region (where it is exposed to surface fluxes of different reactive iodine precursors) and later over the open ocean. According to these sensitivity studies, in the clean marine background atmosphere OIO can be responsible for both homogeneous nuclei formation and the subsequent growth of the clusters to detectable sizes. In contrast to this, in the continental case with its higher levels of pollutants, gas phase OIO mixing ratios, and hence related nucleation rates, are significantly lower. Compared to ternary H2SO4-NH3-H2O nucleation, homogeneous OIO nucleation can be neglected for new particle formation in this case, but OIO can contribute to early particle growth, i.e., to apparent nucleation rates. In general, we found OIO to be more important for the growth of newly formed particles than for the formation of new nuclei. According to our studies, observations of particle "bursts" can only be explained by hot spot-like, not by homogeneously distributed emissions.

  3. Modeling the possible role of iodine oxides in atmospheric new particle formation

    NASA Astrophysics Data System (ADS)

    Pechtl, S.; Lovejoy, E. R.; Burkholder, J. B.; von Glasow, R.

    2005-10-01

    We studied the possible role of iodine oxides in atmospheric new particle formation with the one-dimensional marine boundary layer model MISTRA, which includes chemistry in the gas and aerosol phase as well as aerosol microphysics. The chemical reaction set focuses on halogen (Cl-Br-I) chemistry. We included a two-step nucleation parameterization, where in the first step, the ''real'' nucleation process is parameterized, i.e., the formation of cluster-sized nuclei via homogeneous condensation of gases. We considered both ternary sulfuric acid-ammonia-water nucleation and homomolecular homogeneous OIO nucleation. For the latter, we derived a parameterization based on combined laboratory-model studies. The second step of the nucleation parameterization treats the ''apparent'' nucleation rate, i.e., the growth of clusters into the model's lowest size bin by condensable vapors such as OIO. We compared different scenarios for a clean marine versus a polluted continental background atmosphere. In every scenario, we assumed the air to move, independent of its origin, first over a coastal region (where it is exposed to surface fluxes of different reactive iodine precursors) and later over the open ocean. According to these sensitivity studies, in the clean marine background atmosphere OIO can be responsible for both homogeneous nuclei formation and the subsequent growth of the clusters to detectable sizes. In contrast to this, in the continental case with its higher levels of pollutants, gas phase OIO mixing ratios, and hence related nucleation rates, are significantly lower. Compared to ternary H2SO4-NH3-H2O nucleation, homogeneous OIO nucleation can be neglected for new particle formation in this case, but OIO can contribute to early particle growth, i.e., to apparent nucleation rates. In general, we found OIO to be more important for the growth of newly formed particles than for the formation of new nuclei itself. According to our studies, observations of particle ''bursts'' can only be explained by hot spot-like, not by homogeneously distributed emissions.

  4. Long-term observations of new particle formation in Eastern Mediterranean atmosphere

    NASA Astrophysics Data System (ADS)

    Kalivitis, Nikolaos; Kouvarakis, Giorgos; Bougiatioti, Aikaterini; Stavroulas, Iasonas; Manninen, Hanna E.; Kulmala, Markku; Kerminen, Veli-Matti; Mihalopoulos, Nikolaos

    2015-04-01

    New particle formation (NPF) is a frequent phenomenon in the marine boundary layer (MBL) atmosphere. So far, for the Mediterranean region, NPF events have been reported in the literature but this is the first time that long-term continuous measurements are used to identify and characterize NPF events. We analyzed continuous measurements from the environmental research station of University of Crete at Finokalia, Crete, Greece (35° 20' N, 25° 40' E, 250m a.s.l). The site has been reported to be representative for the eastern Mediterranean MBL atmosphere. Number size distributions of particles in the size range 8 to 848 nm were measured using scanning mobility particle sizer (SMPS) since 2008 (with additional data available for 2004 and 2005 ). Particle growth rates up to the diameter of 25 nm were calculated as well as the condensational sink Additionally, mobility distributions of air ions were measured using an Air Ion Spectrometer (AIS) in the mobility range between 3.2 and 0.0013 cm2V-1s-1 (0.8-42 nm ) for the periods April 2008-April 2009 and December 2012-December 2013. During the NPF event days, the formation and growth rates of sub-3 nm ions could be calculated from AIS data. We found for the Eastern Mediterranean MBL, 22% of the available days could be identified as event days. Although Finokalia is a sub-tropical site with intense photochemistry leading to the production of high concentrations of sulfuric acid, the necessary compound for triggering atmospheric nucleation, NPF at Finokalia has been found to be less frequent than in other locations across Europe. However, NPF takes place all year long indicating that the necessary precursors are available throughout the year. The probability of an event to take place was greatly dependent on the condensational sink, which was two times lower on event than non-event days. The growth rates of the fresh particles presented an annual cycle with maximum values in summer and the average growth rate to 25 nm for all the events was 4.9 ±0.7 nm h-1. Using air ion mobility distributions for the two periods we calculated average growth rate of 2.9 nm h-1 for the diameters 1.5 -3 nm.

  5. Airborne Measured New Particle Formation Event in the Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Platis, Andreas; Altstädter, Barbara; Wehner, Birgit; Wildmann, Norman; Lampert, Astrid; Hermann, Markus; Bange, Jens

    2015-04-01

    A new particle formation (NPF) event measured by unmanned aerial systems is presented. The NPF occurred during the morning transition of the atmospheric boundary-layer near Melpitz, Germany, during springtime. Airborne measurements were able to capture the morning transition continuously from a shallow convective boundary layer below a strong capping inversion layer to a mixed boundary layer with high temporal and spatial resolution of thermodynamics, turbulence and nucleation mode particles number concentrations. Airborne measured vertical profiles from the surface up to 1000 m show the start of a NPF event with enhanced concentrations of nucleation mode particles within the thermal inversion. We show that the inversion layer was responsible for creating favorable thermodynamic conditions for a NPF. Strong gradients of mean potential temperature and mixing ratio, as well as a 10 times higher temperature structure parameter CT2 and 5 times higher humidity structure parameter CQ2 than in the remaining parts of the vertical profile were observed in the inversion. Only high turbulent fluctuations of temperature and humidity plus relatively high dissipation rates create the conditions for supersaturation of precursor gases due to non-linear mixing. Further an anti-correlation of temperature and humidity fluctuations is observed in the layer, where new particle formation is assumed. Our observations support the hypothesis that NPF is likely to be initiated by the thermodynamics and turbulence of the inversion. With the estimation of turbulent mixing and dissipation rates we could prove that the downward transport of particles by convective eddies is the cause of the sudden increase of nucleation mode particles in ground data. Thus, it is very likely that these particles observed at the ground were formed locally at higher altitudes and mixed downwards. These observations have consequences for the interpretation of many earlier published ground-based observations of new NPF. In the morning, stable thermal stratification may trap enhanced concentrations of nucleation mode particles. Once daytime convection initiates, turbulence mixes the boundary layer, and the vertical profile of nucleation mode particles becomes more homogeneous. Without the airborne in-situ measurements, the observations at ground level could lead to a misinterpretation of location and processes causing the increase in nucleation mode particles.

  6. HEAT GENERATION OF SPENT BED MATERIALS FROM ATMOSPHERIC FLUIDIZED-BED COMBUSTION OF COAL

    EPA Science Inventory

    The report describes an experimental investigation of the hydration process of spent bed material (with a calcium/sulfur ratio of 3) from an atmospheric fluidized bed combustor for maximum temperature, rate of temperature rise, and controllability of temperature rise with various...

  7. Mechanistic modelling of Middle Eocene atmospheric carbon dioxide using fossil plant material

    Microsoft Academic Search

    Michaela Grein; Anita Roth-Nebelsick; Volker Wilde; Wilfried Konrad; Torsten Utescher

    2010-01-01

    Various proxies (such as pedogenic carbonates, boron isotopes or phytoplankton) and geochemical models were applied in order to reconstruct palaeoatmospheric carbon dioxide, partially providing conflicting results. Another promising proxy is the frequency of stomata (pores on the leaf surface used for gaseous exchange). In this project, fossil plant material from the Messel Pit (Hesse, Germany) is used to reconstruct atmospheric

  8. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules

    PubMed Central

    Schobesberger, Siegfried; Junninen, Heikki; Bianchi, Federico; Lönn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K.; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P.; Rondo, Linda; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S.; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M.; Worsnop, Douglas R.

    2013-01-01

    Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molecules and then form growing clusters of one to three sulfuric acid molecules plus one to four oxidized organics. Most of these organic compounds retain 10 carbon atoms, and some of them are remarkably highly oxidized (oxygen-to-carbon ratios up to 1.2). The average degree of oxygenation of the organic compounds decreases while the clusters are growing. Our measurements therefore connect oxidized organics directly, and in detail, with the very first steps of new particle formation and their growth between 1 and 2 nm in a controlled environment. Thus, they confirm that oxidized organics are involved in both the formation and growth of particles under ambient conditions. PMID:24101502

  9. Probing Heterogeneous Chemistry of Individual Atmospheric Particles Using Scanning Electron Microscopy and Energy-Dispersive X-ray Analysis

    Microsoft Academic Search

    Brenda J. Krueger; Vicki H. Grassian; Martin J. Iedema; James P. Cowin; Alexander Laskin

    2003-01-01

    In this paper, we demonstrate the utility of single-particle analysis to investigate the chemistry of isolated, individual particles of atmospheric relevance such as NaCl, sea salt, CaCO3, and SiO2. A variety of state-of-th-art scanning electron microscopy techniques, including environmental scanning electon microscopy and computer-controlled scanning electron microscopy\\/energy-dispersive X-ray analysis, were utilized for monitoring and quantifying phase transitions of individual particles,

  10. Automated Instrumentation for the Measurement of Atmospheric Trace Gases and Particles

    NASA Astrophysics Data System (ADS)

    Poruthoor, Simon K.

    Diffusion based separation and collection of gases, followed by filter collection of particles, is the method of choice in the present practice of atmospheric analysis. This approach is especially useful where a species is concurrently present in both phases, e.g., measurement of gaseous nitric acid in presence of particulate nitrate. Presently available techniques require batch processing, are labor intensive and difficult to automate, and exhibit poor time resolution. Continuously operating automated diffusion based gas analyzers were made for the first time by modifying a glass surface to a very highly wettable form with porous silica coating. A novel parallel plate geometry was used. It is simple to construct and offers excellent gas collection efficiency and negligible particle loss, far superior to other existing designs. Coupled to an ion chromatograph (IC), the detection limit of SO_2 for such a system was established to be less than 500 parts per quadrillion (ppq) with a time resolution of eight minutes. Corresponding values for nitrous acid and nitric acid are 110 ppq and 230 ppq, respectively. Downstream particle collection is automated by another novel approach involving vapor super saturation, vapor condensation, impaction and the thermophoretic effect. Steam is injected into the aerosol stream followed by thermoelectric cooling. The steam condenses on particles to form fine droplets. These droplets agglomerate and impact on the walls of the cooled maze-like flow path and the liquid is then collected in a simple inertial air/liquid separator. The liquid is sent to the IC for analysis. The whole system operates continuously and provides essentially quantitative particle collection (99 + % for NaNO_3, (NH_4)_2SO _4, NH_4NO _3 and H_2SO _4 particles of micrometer and submicrometer size). The system also offers excellent sensitivity (detection limits of particulate sulfate, nitrite and nitrate are 2.2 ng/m^3, 0.6 ng/m^3 , and 5.1 ng/m^3, respectively).

  11. The effect of atmospheric aerosol particles and clouds on Net Ecosystem Exchange in Amazonia

    NASA Astrophysics Data System (ADS)

    Cirino, G. G.; Souza, R. F.; Adams, D. K.; Artaxo, P.

    2013-11-01

    Carbon cycling in Amazonia is closely linked to atmospheric processes and climate in the region as a consequence of the strong coupling between the atmosphere and biosphere. This work examines the effects of changes in net radiation due to atmospheric aerosol particles and clouds on the Net Ecosystem Exchange (NEE) of CO2 in the Amazon region. Some of the major environmental factors affecting the photosynthetic activity of plants, such as air temperature and relative humidity were also examined. An algorithm for clear-sky irradiance was developed and used to determine the relative irradiance f, which quantifies the percentage of solar radiation absorbed and scattered due to atmospheric aerosol particles and clouds. Aerosol optical depth (AOD) was calculated from irradiances measured with the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor, onboard the TERRA and AQUA satellites, and was validated with ground-based AOD measurements from AERONET sun photometers. Carbon fluxes were measured using eddy-correlation techniques at LBA (The Large Scale Biosphere-Atmosphere Experiment in Amazonia) flux towers. Two sites were studied: the Biological Reserve of Jaru (located in Rondonia) and the Cuieiras Biological Reserve (located in a preserved region in central Amazonia). In the Jaru Biological Reserve, a 29% increase in carbon uptake (NEE) was observed when the AOD ranged from 0.10 to 1.5. In the Cuieiras Biological Reserve, this effect was smaller, accounting for an approximately 20% increase in NEE. High aerosol loading (AOD above 3 at 550 nm) or cloud cover leads to reductions in solar flux and strong decreases in photosynthesis up to the point where NEE approaches 0. The observed increase in NEE is attributed to an enhancement (~50%) in the diffuse fraction of photosynthetic active radiation (PAR). Significant changes in air temperature and relative humidity resulting from changes in solar radiation fluxes under high aerosol loading were also observed at both sites. Considering the long-range transport of aerosols in Amazonia, the observed changes in NEE for these two sites may occur over large areas in Amazonia, significantly altering the carbon balance in the largest rainforest of the world.

  12. SiC particle cracking in powder metallurgy processed aluminum matrix composite materials

    Microsoft Academic Search

    B. Wang; G. M. Janowski; B. R. Patterson

    1995-01-01

    Particle cracking is one of the key elements in the fracture process of particulate-reinforced metal-matrix composite (MMC)\\u000a materials. The present study quantitatively examined the amount of new surface area created by particle cracking and the number\\u000a fraction of cracked particles in a series of SiC-reinforced aluminum-matrix composite materials. These composite materials\\u000a were fabricated by liquid-phase sintering and contained 9 vol

  13. SiC particle cracking in powder metallurgy processed aluminum matrix composite materials

    Microsoft Academic Search

    B. Wang; G. M. Janowski; B. R. Patterson

    1995-01-01

    Particle cracking is one of the key elements in the fracture process of particulate-reinforced metal-matrix composite (MMC) materials. The present study quantitatively examined the amount of new surface area created by particle cracking and the number fraction of cracked particles in a series of SiC-reinforced aluminum-matrix composite materials. These composite materials were fabricated by liquid-phase sintering and contained 9 vol

  14. Photochemistry of iron(III)-carboxylato complexes in aqueous atmospheric particles

    NASA Astrophysics Data System (ADS)

    Weller, Christian; Herrmann, Hartmut

    2010-05-01

    Iron is always present in the atmosphere in concentrations from ~10-9 M (clouds, rain) up to ~10-3 M (fog, particles). Sources are mainly mineral dust emissions. Iron complexes are very good absorbers in the UV-VIS actinic region and therefore photo-chemically reactive. Iron complex photolysis leads to radical production and can initiate radical chain reactions, which is related to the oxidizing capacity of the atmosphere. These radical chain reactions are involved in the decomposition and transformation of a variety of chemical compounds in cloud droplets and deliquescent particles. Additionally, the photochemical reaction itself can be a degradation pathway for organic compounds with the ability to bind iron. Iron-complexes of atmospherically relevant coordination compounds like oxalate, malonate, succinate, glutarate, tartronate, gluconate, pyruvate and glyoxalate have been investigated in laboratory experiments. Iron speciation depends on the iron-ligand ratio and the pH. The most suitable experimental conditions were calculated with a speciation program (Visual Minteq). The solutions were prepared accordingly and transferred to a 1 cm quartz cuvette and flash-photolyzed with an excimer laser at wavelengths 308 or 351 nm. Photochemically produced Fe2+ has been measured by spectrometry at 510 nm as Fe(phenantroline)32+. Fe2+ overall effective quantum yields have been calculated with the concentration of photochemically produced Fe2+ and the measured energy of the excimer laser pulse. The laser pulse energy was measured with a pyroelectric sensor. For some iron-carboxylate systems the experimental parameters like the oxygen content of the solution, the initial iron concentration and the incident laser energy were systematically altered to observe an effect on the overall quantum yield. The dependence of some quantum yields on these parameters allows in some cases an interpretation of the underlying photochemical reaction mechanism. Quantum yields of malonate, glutarate and gluconate complexes lie in the range of 0.02

  15. Atmospheric trace element concentrations in total suspended particles near Paris, France

    NASA Astrophysics Data System (ADS)

    Ayrault, Sophie; Senhou, Abderrahmane; Moskura, Mélanie; Gaudry, André

    2010-09-01

    To evaluate today's trace element atmospheric concentrations in large urban areas, an atmospheric survey was carried out for 18 months, from March 2002 to September 2003, in Saclay, nearby Paris. The total suspended particulate matter (TSP) was collected continuously on quartz fibre filters. The TSP contents were determined for 36 elements (including Ag, Bi, Mo and Sb) using two analytical methods: Instrumental Neutron Activation Analysis (INAA) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The measured concentrations were in agreement within the uncertainties with the certified values for the polycarbonate reference material filter SRM-2783 (National Institute for Standard Technology NIST, USA). The measured concentrations were significantly lower than the recommended atmospheric concentrations. In 2003, the Pb atmospheric level at Saclay was 15 ng/m 3, compared to the 500 ng/m 3 guideline level and to the 200 ng/m 3 observed value in 1994. The typical urban background TSP values of 1-2, 0.2-1, 4-6, 10-30 and 3-5 ng/m 3 for As, Co, Cr, Cu and Sb, respectively, were inferred from this study and were compared with the literature data. The typical urban background TSP concentrations could not be realised for Cd, Pb and Zn, since these air concentrations are highly influenced by local features. The Zn concentrations and Zn/Pb ratio observed in Saclay represented a characteristic fingerprint of the exceptionally large extent of zinc-made roofs in Paris and its suburbs. The traffic-related origin of Ba, Cr, Cu, Pb and Sb was demonstrated, while the atmospheric source(s) of Ag was not identified.

  16. Simulated atmospheric processing of iron oxyhydroxide minerals at low pH: Roles of particle size and acid anion in iron dissolution

    PubMed Central

    Rubasinghege, Gayan; Lentz, Robert W.; Scherer, Michelle M.; Grassian, Vicki H.

    2010-01-01

    A number of recent studies have shown that iron dissolution in Fe-containing dust aerosol can be linked to source material (mineral or anthropogenic), mineralogy, and iron speciation. All of these factors need to be incorporated into atmospheric chemistry models if these models are to accurately predict the impact of Fe-containing dusts into open ocean waters. In this report, we combine dissolution measurements along with spectroscopy and microscopy to focus on nanoscale size effects in the dissolution of Fe-containing minerals in low-pH environments and the importance of acid type, including HNO3, H2SO4, and HCl, on dissolution. All of these acids are present in the atmosphere, and dust particles have been shown to be associated with nitrate, sulfate, and/or chloride. These measurements are done under light and dark conditions so as to simulate and distinguish between daytime and nighttime atmospheric chemical processing. Both size (nano- versus micron-sized particles) and anion (nitrate, sulfate, and chloride) are found to play significant roles in the dissolution of ?-FeOOH under both light and dark conditions. The current study highlights these important, yet unconsidered, factors in the atmospheric processing of iron-containing mineral dust aerosol. PMID:20360560

  17. (Bio)hybrid materials based on optically active particles

    NASA Astrophysics Data System (ADS)

    Reitzig, Manuela; Härtling, Thomas; Opitz, Jörg

    2014-03-01

    In this contribution we provide an overview of current investigations on optically active particles (nanodiamonds, upconversion phospors) for biohybrid and sensing applications. Due to their outstanding properties nanodiamonds gain attention in various application elds such as microelectronics, optical monitoring, medicine, and biotechnology. Beyond the typical diamond properties such as high thermal conductivity and extreme hardness, the carbon surface and its various functional groups enable diverse chemical and biological surface functionalization. At Fraunhofer IKTS-MD we develop a customization of material surfaces via integration of chemically modi ed nanodiamonds at variable surfaces, e.g bone implants and pipelines. For the rst purpose, nanodiamonds are covalently modi ed at their surface with amino or phosphate functionalities that are known to increase adhesion to bone or titanium alloys. The second type of surface is approached via mechanical implementation into coatings. Besides nanodiamonds, we also investigate the properties of upconversion phosphors. In our contribution we show how upconversion phosphors are used to verify sterilization processes via a change of optical properties due to sterilizing electron beam exposure.

  18. Modelling the contribution of biogenic VOCs to new particle formation in the Jülich plant atmosphere chamber

    NASA Astrophysics Data System (ADS)

    Liao, L.; Dal Maso, M.; Mogensen, D.; Roldin, P.; Rusanen, A.; Kerminen, V.-M.; Mentel, T. F.; Wildt, J.; Kleist, E.; Kiendler-Scharr, A.; Tillmann, R.; Ehn, M.; Kulmala, M.; Boy, M.

    2014-11-01

    We used the MALTE-BOX model including near-explicit air chemistry and detailed aerosol dynamics to study the mechanisms of observed new particle formation events in the Jülich Plant Atmosphere Chamber. The modelled and measured H2SO4 (sulfuric acid) concentrations agreed within a factor of two. The modelled total monoterpene concentration was in line with PTR-MS observations, and we provided the distributions of individual isomers of terpenes, when no measurements were available. The aerosol dynamic results supported the hypothesis that H2SO4 is one of the critical compounds in the nucleation process. However, compared to kinetic H2SO4 nucleation, nucleation involving OH oxidation products of monoterpenes showed a better agreement with the measurements, with R2 up to 0.97 between modelled and measured total particle number concentrations. The nucleation coefficient for kinetic H2SO4 nucleation was 2.1 × 10-11 cm3 s-1, while the organic nucleation coefficient was 9.0 × 10-14 cm3 s-1. We classified the VOC oxidation products into two sub-groups including extremely low-volatility organic compounds (ELVOCs) and semi-volatile organic compounds (SVOCs). These ELVOCs and SVOCs contributed approximately equally to the particle volume production, whereas only ELVOCs made the smallest particles to grow in size. The model simulations revealed that the chamber walls constitute a major net sink of SVOCs on the first experiment day. However, the net wall SVOC uptake was gradually reduced because of SVOC desorption during the following days. Thus, in order to capture the observed temporal evolution of the particle number size distribution, the model needs to consider reversible gas-wall partitioning.

  19. An absorption model of gas\\/particle partitioning of organic compounds in the atmosphere

    Microsoft Academic Search

    JAMES F. PANKOW

    1994-01-01

    An equation that can successfully parameterize gas-particle partitioning is Kp(m3\\/~g -1) =(F\\/TSP)\\/A, where Kp is a partitioning constant, TSP (pgm -3) is the concentration of total suspended particulate material, and F (ngm -3) and A (ngm-3), respectively, are the particulate-associated and gaseous concentrations of the compound of interest. By itself, this equation does not indicate whether the partitioning is primarily

  20. Observational and laboratory studies of optical properties of black and brown carbon particles in the atmosphere using spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Nakayama, Tomoki; Matsumi, Yutaka

    2015-04-01

    Light absorption and scattering by aerosols are as an important contributor to radiation balance in the atmosphere. Black carbon (BC) is considered to be the most potent light absorbing material in the visible region of the spectrum, although light absorbing organic carbon (brown carbon or BrC) and mineral dust may also act as sources of significant absorption, especially in the ultraviolet (UV) and shorter visible wavelength regions. The optical properties of such particles depend on wavelength, particle size and shape, morphology, coating, and complex refractive index (or chemical composition), and therefore accurate in situ measurements of the wavelength dependence of the optical properties of particles are needed. Recently, cavity ring-down spectroscopy (CRDS) and photoacoustic spectroscopy (PAS) have been used for the direct measurements of extinction and absorption coefficients of particles suspended in air. We have applied these techniques to the observational studies of optical properties of BC and BrC in an urban site in Japan and to the laboratory studies of optical properties of secondary organic aerosols (SOAs) generated from a variety of biogenic and anthropogenic volatile organic compounds and those of diesel exhaust particles (DEPs). In the presentation, the basic principles of these techniques and the results obtained in our studies and in the recent literatures will be overviewed. References Guo, X. et al., Measurement of the light absorbing properties of diesel exhaust particles using a three-wavelength photoacoustic spectrometer, Atmos. Environ., 94, 428-437 (2014). Nakayama, T. et al., Measurements of aerosol optical properties in central Tokyo during summertime using cavity ring-down spectroscopy: Comparison with conventional techniques, Atmos. Environ., 44, 3034-3042 (2010). Nakayama, T. et al., Laboratory studies on optical properties of secondary organic aerosols generated during the photooxidation of toluene and the ozonolysis of alpha-pinene, J. Geophys. Res., 115, D24204, doi:10.1029/2010JD014387 (2010). Nakayama, T. et al., Wavelength dependence of refractive index of secondary organic aerosols generated during the ozonolysis and photooxidation of alpha-pinene, SOLA, 8, 119-124 (2012). Nakayama, T. et al., Wavelength and NOx dependent complex refractive index of SOAs generated from the photooxidation of toluene, Atmos. Chem. Phys., 13, 531-545 (2013). Nakayama, T. et al., Properties of light-absorbing aerosols in the Nagoya urban area, Japan, in August 2011 and January 2012: Contributions of brown carbon and lensing effect, J. Geophys. Res. Atmos., 119, 12721-12739 (2014). Nakayama, T. et al., Characterization of a three wavelength photoacoustic soot spectrometer (PASS-3) and a photoacoustic extinctiometer (PAX), J. Meteor. Soc. Japan, (2015, in press).

  1. Development of a computer model for calculation of radioactive materials into the atmosphere after an accident

    SciTech Connect

    Schershakov, V. [Federal Information Analytical Centre, Obinski (Russia)

    1997-11-01

    Secondary atmospheric contamination with radioactive dust and chemical species deposited on the ground and resuspended by wind occur very widely. This process is particularly pronounced in case of extensive contamination of soil and under extreme weather conditions, for example, during dust storms. The mechanism of wind dust generation consists in the following. At low wind speed U=2-3 m/s, which is most common in midlatitude, small radioactive dust particles (diameter of hundredth of a micron to 10-20 microns) are lifted from soil surface due to turbulent vortexes. Under the gravitational force the particles of 1-2 micron diameter practically do not settle. Larger dust particles cannot remain in the air for a long time: they are lifted by turbulent vortexes and settle, their motion in the wind flow is jump-wise and the interaction of particles with the flow is called saltation /I/. Saltation is the main mechanism of dust generation up to the wind velocity at which wind erosion starts. The size of dust particles can be as large as 100 pm. When dropping they can be ricocheting from ground or pass the impulse to other particles which begin rolling over and jumping up. The process of dust transport by wind can be compared to a chain reaction. At the velocity of 10 m/s large particles of about 500 pm stop skipping and roll over only, while particles of more than 1 mm remain stationary. Thus, the fine fraction is blown out from the polydispersed soil particles. The intensity of wind resuspension of radioactive dust from the ground is characterized either by a resuspension factor or a resuspension rate.

  2. Atmosphere expansion and mass loss of close-orbit giant exoplanets heated by stellar XUV: I. Modeling of hydrodynamic escape of upper atmospheric material

    E-print Network

    Shaikhislamov, I F; Sasunov, Yu L; Lammer, H; Kislyakova, K G; Erkaev, N V

    2015-01-01

    In the present series of papers we propose a consistent description of the mass loss process. To study the effects of intrinsic magnetic field of a close-orbit giant exoplanet (so-called Hot Jupiter) on the atmospheric material escape and formation of planetary inner magnetosphere in a comprehensive way, we start with a hydrodynamic model of an upper atmosphere expansion presented in this paper. While considering a simple hydrogen atmosphere model, we focus on selfconsistent inclusion of the effects of radiative heating and ionization of the atmospheric gas with its consequent expansion in the outer space. Primary attention is paid to investigation of the role of specific conditions at the inner and outer boundaries of the simulation domain, under which different regimes of material escape (free- and restricted- flow) are formed. Comparative study of different processes, such as XUV heating, material ionization and recombination, H3+ cooling, adiabatic and Lyman-alpha cooling, Lyman-alpha reabsorption is perf...

  3. Fatty acids in the marine atmosphere: Factors governing their concentrations and evaluation of organic films on sea-salt particles

    NASA Astrophysics Data System (ADS)

    Mochida, Michihiro; Kitamori, Yasuyuki; Kawamura, Kimitaka; Nojiri, Yukihiro; Suzuki, Keisuke

    2002-09-01

    Fatty acids (C14-C32) in the marine boundary layer were measured in aerosols that were collected over the northern North Pacific from October 1996 to June 1997. Concentrations of lower molecular weight (C14-C19) saturated fatty acids (LFAs, 0.8-24 ng m-3) showed a positive correlation with sea-salt concentrations, suggesting that LFAs are released from the ocean surface to the atmosphere with sea-salt particles. The averaged ratios of [LFAs]air/[sea salt] in autumn, winter, spring and summer seasons were 1.8 (±1.3) × 10-4, 2.1 (±1.3) × 10-4, 3.7 (±2.9) × 10-4, and 4.6 (±1.8) × 10-4, respectively. The results indicate the seasonal variation of the sea-to-air flux of LFAs relative to that of sea salt with a maximum in spring to summer. The enhanced LFA flux was consistent with the satellite images of chlorophyll a over the northern North Pacific, which showed high biological productivity from spring to summer. On the basis of the ratios of [LFAs]air/[sea salt], relative humidity, and modeled size distribution of sea-salt particles, the coverage of LFAs on sea-salt particles was estimated to range from 0.3 to 14%. This study suggests that the coverage of fatty acids, together with other film-forming materials, may have a significant effect on the physicochemical properties of aerosols, which may be affected by the high biological productivity in the high latitudinal ocean.

  4. Effect of temperature, atmospheric condition, and particle size on extinction in a plume of volatile aerosol dispersed in the atmospheric surface layer.

    PubMed

    Tsang, T T; Pai, P; Korgaonkar, N V

    1988-02-01

    The objective of this work is to study the effects of ambient temperature, atmospheric condition, and particle size on the extinction coefficient of diesel fuel and fog oil smoke. A first-order closure model is used to describe the turbulent diffusion of the smoke in the atmospheric surface layer. Mean values of wind speed and diffusivity in the vertical direction are obtained by the use of the Monin-Obukhov similarity theory. The 2-D crosswind line source model also includes the aerosol kinetic processes of evaporation, sedimentation, and deposition. Numerical results are obtained from simulations on a supercomputer. PMID:20523645

  5. Effect of temperature, atmospheric condition, and particle size on extinction in a plume of volatile aerosol dispersed in the atmospheric surface layer

    SciTech Connect

    Tsang, T.T.H.; Pai, P.; Korgaonkar, N.V.

    1988-02-01

    The objective of this work is to study the effects of ambient temperature, atmospheric condition, and particle size on the extinction coefficient of diesel fuel and fog oil smoke. A first-order closure model is used to describe the turbulent diffusion of the smoke in the atmospheric surface layer. Mean values of wind speed and diffusivity in the vertical direction are obtained by the use of the Monin-Obukhov similarity theory. The 2-D crosswind line source model also includes the aerosol kinetic processes of evaporation, sedimentation, and deposition. Numerical results are obtained from simulations on a supercomputer.

  6. Application of Atmospheric Plasma-Sprayed Ferrite Layers for Particle Accelerators

    E-print Network

    Caspers, F; Federmann, S; Taborelli, M; Schulz, C; Bobzin, K; Wu, J

    2013-01-01

    A common problem in all kinds of cavity-like structures in particle accelerators is the occurrence of RF-resonances. Typically, ferrite plates attached to the walls of such structures as diagnostic devices, kickers or collimators, are used to dampen those undesired modes. However, the heat transfer rate from these plates to the walls is rather limited. Brazing ferrite plates to the walls is not possible in most cases due to the different thermal expansion coefficients. To overcome those limitations, atmospheric plasma spraying techniques have been investigated. Ferrite layers with a thickness from 50 ?m to about 300 ?m can be deposited on metallic surfaces like stainless steel exhibiting good thermal contact and still reasonable absorption properties. In this paper the technological aspects of plasma deposition are discussed and results of specifically developed RF loss measurement procedures for such thin magnetically lossy layers on metal are presented.

  7. Gas-to-Particle Conversion in Surface Discharge Nonthermal Plasmas and Its Implications for Atmospheric Chemistry

    PubMed Central

    Kim, Hyun-Ha; Ogata, Atsushi

    2011-01-01

    This paper presents some experimental data on gas-to-particle conversion of benzene using nonthermal plasma (NTP) technology and discusses the possibility of its technical application in atmospheric chemistry. Aerosol measurement using a differential mobility analyzer (DMA) revealed that the parts of benzene molecules were converted into a nanometer-sized aerosol. Aerosol formation was found to be highly related with the missing part in carbon balance. Scanning electron microscopy analysis showed that the aerosols formed in synthetic humid air are the collection of nanoparticles. The carbonyl band (C=O) was found to be an important chemical constituent in the aerosol. The potential of the NTP as an accelerated test tool in studying secondary organic aerosol (SOA) formation from VOCs will be also addressed. PMID:22163781

  8. Measurement of the Hygroscopicity and Wet Removal of Black-Carbon-Containing Particles in the Urban Atmosphere of Tokyo

    NASA Astrophysics Data System (ADS)

    Ohata, Sho; Moteki, Nobuhiro; Mori, Tatsuhiro; Koike, Makoto; Schwarz, Joshua; Takami, Akinori; Kondo, Yutaka

    2015-04-01

    Megacities are very large, concentrated anthropogenic sources of black carbon (BC) aerosols. Freshly emitted BC particles inside megacities affect local air quality and regional and global climate. The microphysical properties (e.g., number size distribution, coating thickness, and hygroscopicity) of atmospheric BC-containing particles are important because their efficiency of wet removal from the atmosphere can be highly dependent on these properties. In this study, we developed a method for independent measurement of the hygroscopicity of BC-free and BC-containing particles, and then applied it to the ambient observation in the urban atmosphere of Tokyo. A single particle soot photometer (SP2) was modified as a humidified-SP2, which quantifies the BC-core mass (BC content within a BC-containing particle) and optical diameter of individual aerosol particles, under controlled relative humidity (RH), by detecting both the laser-induced incandescence emitted and laser light scattered from each particle (Schwarz et al., 2014, Journal of Aerosol Science). Measurements of growth factor (GF) and hygroscopicity parameter ? for BC-free and BC-containing particles can be achieved by combining an aerosol particle mass analyzer with the newly developed humidified-SP2. This method was tested in the laboratory and then employed in ambient observations in summer 2014. The ambient measurements were made while also measuring number size distribution of BC cores in rainwater with a nebulizer-SP2 system. Throughout the observation period, for BC-containing particles with a dry diameter of about 200 nm, the particles with smaller BC fractions tended to represent greater water uptake, and the number fraction of the less hygroscopic (GF < 1.2 at 85% RH) BC-containing particles was more than 70% of the total BC-containing particles. The measured average number size distribution of BC cores in rainwater was larger than that in the surface air before precipitation began, and the dependence of the wet removal of BC-containing particles on their BC-core sizes was successfully explained by the measured microphysical properties of BC-containing particles in the air and an assumed maximum supersaturation that the particles would have experienced during rain events. These measurement data indicated that BC-containing particles in Tokyo, especially particles with small BC cores (or with high critical supersaturation), were efficiently transported upward without being removed by precipitation.

  9. Waveguides in three-dimensional photonic bandgap materials for particle-accelerator on a

    E-print Network

    Byer, Robert L.

    Waveguides in three-dimensional photonic bandgap materials for particle-accelerator on a chip@physics.anu.edu.au Abstract: The quest for less costly and more compact high-energy particle accelerators," in Proceedings of Particle Accelerator Conference 2011, (2011) pp. 277­279. 12. M. Deubel, G. von Freymann, M

  10. Improved utilization of desiccant material in packed bed dehumidifier using composite particles

    Microsoft Academic Search

    R. Kadoli; T. P. Ashok Babu

    2011-01-01

    Solid desiccant dehumidifiers are widely used in drying processes. In most of these dehumidifiers, the desiccant material is used as packed bed of granule or spherical particles. Investigations of intra-particle heat and mass transfer processes has shown that the entire portion of the particle is not participating effectively during adsorption as well as desorption processes [Pesaran AA, Mills F. Moisture

  11. Ignition Resistance of Polymeric Materials to Particle Impact in High-Pressure Oxygen

    NASA Technical Reports Server (NTRS)

    Forsyth, Elliot T.; Stolzfus, Joel M.; Fries, Joseph (Technical Monitor)

    2000-01-01

    Particle impact ignition has been the primary cause of numerous fires in oxygen systems. This ignition phenomenon is known to occur where particles are present in high-velocity gas, and where impact occurs on a flammable material. The particle impact ignition behavior of many metals has been widely studied, but the particle impact ignition behavior of polymeric materials is relatively unknown. Particle impact ignition in polymeric materials is a concern as these materials are commonly used in component seat and seal applications, where high-velocity particle impacts can occur. This study evaluates several polymeric materials and compares the minimum temperature required for ignition (threshold temperature) of these materials: Kel-F 81 (CTFE), Teflon (PTFE), PEEK, Vespel SP-21, and Nylon 6/6. The materials were configured as targets in the White Sands Test Facility high-velocity particle impact test system. Gaseous oxygen was flowed at 4000 psi and sonic velocity, and the targets were impacted with 2000-micron aluminum 2017 particles. This paper discusses the results of these tests and ranks the materials according to their threshold temperatures at these conditions.

  12. Viscosity of -pinene secondary organic material and implications for particle growth and reactivity

    E-print Network

    Viscosity of -pinene secondary organic material and implications for particle growth and reactivity of secondary organic material (SOM) are abun- dant in the lower troposphere. The viscosity of these particles-mobility" technique and a "poke-flow" technique, in conjunction with simulations of fluid flow, the viscosity

  13. Material response to particle impact during abrasive jet machining of alumina ceramics

    Microsoft Academic Search

    Manabu Wakuda; Yukihiko Yamauchi; Shuzo Kanzaki

    2003-01-01

    Abrasive jet machining (AJM), a specialized form of shot blasting, attracts much attention as a hopeful micro-machining method for hard, brittle materials such as structural ceramics. The present paper attempts to identify the material response of alumina ceramics to the abrasive particle impact in the AJM process. Three kinds of commercial abrasive particles were utilized to dimple the sintered alumina

  14. Equalizing the near and far electromagnetic fields around particles made of different materials

    E-print Network

    Devilez, Alexis; Stout, Brian; Bonod, Nicolas

    2015-01-01

    We demonstrate that the electromagnetic fields scattered by particles made of different materials can be equalized. Emphasize is placed first in metallic nanoparticles that host localized surface plasmons and it is shown that their electromagnetic fields can be identically reproduced with dielectric particles. We derive the explicit formulas relating the different constitutive parameters that yield identical electromagnetic responses. This method provides the dielectric permittivities of spherical particles that reproduce the strong near electric field intensities observed around metallic particles featuring localized surface plasmon resonances in optics or near infrared frequencies. We also demonstrate the ability of homogenous dielectric particles to host the magnetic resonances predicted for exotic materials with negative permeability.

  15. Effect of atmospheric ageing on volatility and ROS of biodiesel exhaust nano-particles

    NASA Astrophysics Data System (ADS)

    Pourkhesalian, A. M.; Stevanovic, S.; Rahman, M. M.; Faghihi, E. M.; Bottle, S. E.; Masri, A. R.; Brown, R. J.; Ristovski, Z. D.

    2015-03-01

    In the prospect of limited energy resources and climate change, effects of alternative biofuels on primary emissions are being extensively studied. Our two recent studies have shown that biodiesel fuel composition has a~significant impact on primary particulate matter emissions. It was also shown that particulate matter caused by biodiesels was substantially different from the emissions due to petroleum diesel. Emissions appeared to have higher oxidative potential with the increase in oxygen content and decrease of carbon chain length and unsaturation levels of fuel molecules. Overall, both studies concluded that chemical composition of biodiesel is more important than its physical properties in controlling exhaust particle emissions. This suggests that the atmospheric ageing processes, including secondary organic aerosol formation, of emissions from different fuels will be different as well. In this study, measurements were conducted on a modern common-rail diesel engine. To get more information on realistic properties of tested biodiesel particulate matter once they are released into the atmosphere, particulate matter was exposed to atmospheric oxidants, ozone and ultra-violet light; and the change in their properties was monitored for different biodiesel blends. Upon the exposure to oxidative agents, the chemical composition of the exhaust changes. It triggers the cascade of photochemical reactions resulting in the partitioning of semi-volatile compounds between the gas and particulate phase. In most of the cases, aging lead to the increase in volatility and oxidative potential, and the increment of change was mainly dependent on the chemical composition of fuels as the leading cause for the amount and the type of semi-volatile compounds present in the exhaust.

  16. Particle-induced damage and subsequent healing of materials: Erosion, corrosion and self-healing coatings

    Microsoft Academic Search

    Akihiro Yabuki

    2011-01-01

    This review summarizes research on particle-induced damage and the subsequent repair of metallic materials. Metallic materials are damaged by solid particle impact via two damage processes: repeated plastic deformation and cutting. At a certain low-impact velocity, the particle does not skid, resulting in only plastic deformation with no damage by cutting. The critical impact velocity has been theoretically derived. Self-healing

  17. Heterogeneous Combustion Particles with Distinctive Light-Absorbing and Light-Scattering Phases as Mimics of Internally-Mixed Ambient Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Conny, J. M.; Ma, X.; Gunn, L. R.

    2011-12-01

    Particles with heterogeneously-distributed light-absorbing and light-scattering phases were generated from incomplete combustion or thermal decomposition to mimic real atmospheric particles with distinctive optical properties. Individual particles and particle populations were characterized microscopically. The purpose was to examine how optical property measurements of internally-mixed ambient air particles might vary based on the properties of laboratory-generated particles produced under controlled conditions. The project is an initial stage in producing reference samples for calibrating instrumentation for monitoring climatically-important atmospheric aerosols. Binary-phase particles containing black carbon (BC) and a metal or a metal oxide phase were generated from the thermal decomposition or partial combustion of liquid fuels at a variety of temperatures from 600 °C to 1100 °C. Fuels included mixtures of toluene or isooctane and iron pentacarbonyl or titanium tetrachloride. Scanning electron microscopy with energy-dispersive x-ray spectroscopy revealed that burning the fuels at different temperatures resulted in distinctive differences in morphology and carbon vs. metal/metal oxide composition. Particles from toluene/Fe(CO)5 thermal decomposition exhibited aggregated morphologies that were classified as dendritic, soot-like, globular, or composited (dendritic-globular). Particles from isooctane/TiCl4 combustion were typically spherical with surface adducts or aggregates. Diameters of the BC/TiO2 particles averaged 0.68 ?m to 0.70 ?m. Regardless of combustion temperature, the most abundant particles in each BC/TiO2 sample had an aspect ratio of 1.2. However, for the 600 °C and 900 °C samples the distribution of aspect ratios was skewed toward much larger ratios suggesting significant chainlike aggregation. Carbon and titanium compositions (wt.) for the 600 °C sample were 12 % and 53 %, respectively. In contrast, the composition trended in the opposite direction for the 900 °C sample with carbon at 57 % and titanium at 27 %.

  18. Particle impact damping: influence of material and size

    E-print Network

    Marhadi, Kun Saptohartyadi

    2005-02-17

    , steel dust, and sand. The effects of particle size are also investigated. Particle diameters are varied from about 0.2 mm to 3 mm. The experimental data collected is offered as a resourceful database for future development of an analytical model...

  19. Development and characterization of an ion trap mass spectrometer for the on-line chemical analysis of atmospheric aerosol particles

    Microsoft Academic Search

    Andreas Kürten; Joachim Curtius; Frank Helleis; Edward R. Lovejoy; Stephan Borrmann

    2007-01-01

    A novel Ion Trap Aerosol Mass Spectrometer (IT-AMS) for atmospheric particles has been developed and characterized. With this instrument the chemical composition of the non-refractory component of aerosol particles can be measured quantitatively. The set-up makes use of the well-characterized inlet and vaporization\\/ionization system of the Aerodyne Aerosol Mass Spectrometer (AMS). While the AMS uses either a linear quadrupole mass

  20. Solubility of methanol in low-temperature aqueous sulfuric acid and implications for atmospheric particle composition

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Essin, Andrew M.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    Using traditional Knudsen cell techniques, we find well-behaved Henry's law uptake of methanol in aqueous 45 - 70 wt% H2SO4 solutions at temperatures between 197 and 231 K. Solubility of methanol increases with decreasing temperature and increasing acidity, with an effective Henry's law coefficient ranging from 10(exp 5) - 10(exp 8) M/atm. Equilibrium uptake of methanol into sulfuric acid aerosol particles in the upper troposphere and lower stratosphere will not appreciably alter gas-phase concentrations of methanol. The observed room temperature reaction between methanol and sulfuric acid is too slow to provide a sink for gaseous methanol at the temperatures of the upper troposphere and lower stratosphere. It is also too slow to produce sufficient quantities of soluble reaction products to explain the large amount of unidentified organic material seen in particles of the upper troposphere.

  1. Autofluorescence of atmospheric bioaerosols - fluorescent biomolecules, biological standard particles and potential interferences

    NASA Astrophysics Data System (ADS)

    Pöhlker, C.; Huffmann, J. A.; Pöschl, U.

    2012-04-01

    Primary biological aerosol particles (PBAP) such as pollen, fungal spores, bacteria, biogenic polymers and debris from larger organisms are known to influence atmospheric chemistry and physics, the biosphere and public health. PBAP account for up to ~30% of fine and up to ~70% of coarse particulate matter in urban, rural and pristine environment and are released with estimated emission rates of up to ~1000 Tg/a [1]. Continuous measurements of the abundance, variability and diversity of PBAP have been difficult until recently, however. The application of on-line instruments able to detect autofluorescence from biological particles in real-time has been a promising development for the measurement of PBAP concentrations and fluxes in different environments [2,3]. The detected fluorescent biological aerosol particles (FBAP) can be regarded as a subset of PBAP, although the exact relationship between PBAP and FBAP is still being investigated. Autofluorescence of FBAP is usually a superposition of fluorescence from a mixture of individual fluorescent molecules (fluorophores). Numerous biogenic fluorophores such as amino acids (e.g., tryptophan, tyrosine), coenzymes (e.g., NAD(P)H, riboflavin) and biopolymers (e.g., cellulose) emit fluorescent light due to heterocyclic aromatic rings or conjugated double bonds within their molecular structures. The tryptophan emission peak is a common feature of most bioparticles because the amino acid is a constituent of many proteins and peptides. The influence of the coenzymes NAD(P)H and riboflavin on the autofluorescence of bacteria can be regarded as an indicator for bacterial metabolism and has been utilized to discriminate between viable and non-viable organisms [4]. However, very little information is available about other essential biofluorophores in fungal spores and pollen. In order to better understand the autofluorescence behavior of FBAP, we have used fluorescence spectroscopy and fluorescence microscopy to analyze standard bioparticles (pollen, fungal spores, and bacteria) as well as atmospherically relevant chemical substances. We found varying levels of fluorescent emission and significant differences in the spectral properties of major PBAP classes. The combination will support the quantitative interpretation of data obtained by real-time FBAP instrumentation [5]. [1] Elbert, W., Taylor, P. E., Andreae, M. O., & Pöschl, U. (2007). Atmos. Chem. Phys., 7, 4569-4588. [2] Huffman, J. A., Treutlein, B., & Pöschl, U. (2010). Atmos. Chem. Phys., 10, 3215-3233. [3] Pöschl, U., et al. (2010). Science, 329, 1513-1516. [4] Lakowicz, J., Principles of fluorescence spectroscopy, Plenum publishers, New York, 1999. [5] Pöhlker, C., Huffman, J. A., & Pöschl, U., (2012). Atmos. Meas. Tech., 5, 37-71.

  2. The Supramolecular NanoMaterials Group From Nano-Particles

    E-print Network

    Materials Group Supramolecular Materials Science Monolayer Protected Metal Nanoparticles Functionalized Carbon Nanotubes Nanowires Supramolecular Lithography Supramolecular Nano Stamping Jackson, Myerson, Stellacci, Nat manuscript in prep. NANO-MATERIALS LITHOGRAPHY 20 m #12;S u N M a G Metal Nanoparticles Synthesis Metal Salt

  3. Highly time-resolved chemical characterization of atmospheric fine particles during 2010 Shanghai World Expo

    NASA Astrophysics Data System (ADS)

    Huang, X.-F.; He, L.-Y.; Xue, L.; Sun, T.-L.; Zeng, L.-W.; Gong, Z.-H.; Hu, M.; Zhu, T.

    2012-06-01

    Shanghai, with a population of over 20 million, is the largest mega-city in China. Rapidly increasing industrial and metropolitan emissions have deteriorated its air quality in the past decades, with fine particle pollution as one of the major issues. However, systematic characterization of atmospheric fine particles with advanced measurement techniques has been very scarce in Shanghai. During 2010 Shanghai World Expo, we deployed a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a single particle soot photometer (SP2) in urban Shanghai between 15 May and 10 June 2010 to measure fine particles with a high time resolution. The 4-min resolution PM1 mass concentration ranged from 5.5 to 155 ?g m-3, with an average of 29.2 ?g m-3. On average, sulfate and organic matter (OM) were the most abundant PM1 components, accounting for 33.3 and 28.7% of the total mass, respectively, while the fraction of nitrate showed an increasing trend with the increasing PM1 loading, indicating the photochemical nature of high fine particle pollution in Shanghai. Taking advantage of HR-ToF-AMS and SP2, OM was found to have an average OM/OC ratio (organic matter mass/organic carbon mass) of 1.55 and black carbon (BC) had an average number fraction of internally mixed BC of 41.2%. Positive matrix factorization (PMF) analysis on the high resolution organic mass spectral dataset identified a hydrocarbon-like (HOA), a semi-volatile oxygenated (SV-OOA), and a low-volatility oxygenated (LV-OOA) organic aerosol component, which on average accounted for 24.0, 46.8, and 29.2% of the total organic mass, respectively. The diurnal patterns of them with interesting time delay possibly implied a photochemical oxidizing process from HOA (and/or its concurrently emitted gaseous organic pollutants) to SV-OOA to LV-OOA. Back trajectory analysis indicated that the northwesterly continental air mass represented the most severe pollutant regional transport condition with the highest nitrate and SV-OOA fractions. In addition, the results in Shanghai were compared with similar measurements performed recently in other mega-cities in the world.

  4. Coupling of Particle Acceleration and Atmospheric Dynamic Response to Impulsive Energy Release in Solar Flares

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Petrosian, V.; Chen, Q.; Mariska, J.

    2012-05-01

    In solar flares, acceleration and transport of high-energy particles and fluid dynamics of the atmospheric plasma are interrelated processes coupled in a circular chain. Chromospheric evaporation, for example, can alter the density and temperature distribution along the flare loop, in particular in the acceleration site near the loop-top source. This produces a feedback on particle collisional heating, and more importantly on the energy release and acceleration process. This in turn will change the heating of the chromosphere and mass flows in the corona. In recent years, there have been increasing theoretical and observational motivations to investigate these coupled processes together in a self-consistent manner. We present here combined Fokker-­Planck modeling of particles and hydrodynamic simulation of flare plasma. We extended our earlier hybrid simulation (Liu, Petrosian, Mariska 2009) by feeding the updated plasma density and temperature at the loop-top source to the stochastic acceleration process. We find that the density enhancement causes the ratio of the electron plasma frequency to gyro-frequency to increase. This can lead to the reduction of the efficiency of electron acceleration and thus the quenching or spectral softening of nonthermal hard X-ray tails observed during the late stages of flares. This also affects the relative production of energetic electrons vs. protons (Petrosian and Liu 2004). We will compare our results with recent observations from RHESSI, SDO, and Hinode. We will also discuss their implications for cyclic spectral hardening, quasi-periodic flare pulsations, and recently imaged super-fast quasi-periodic coronal waves originating from flare kernels.

  5. Microgel particles for the delivery of bioactive materials

    DOEpatents

    Frechet, Jean M. J. (Oakland, CA); Murthy Niren (Atlanta, GA)

    2010-03-23

    Novel microgels, microparticles and related polymeric materials capable of delivering bioactive materials to cells for use as vaccines or therapeutic agents. The materials are made using a crosslinker molecule that contains a linkage cleavable under mild acidic conditions. The crosslinker molecule is exemplified by a bisacryloyl acetal crosslinker. The new materials have the common characteristic of being able to degrade by acid hydrolysis under conditions commonly found within the endosomal or lysosomal compartments of cells thereby releasing their payload within the cell. The materials can also be used for the delivery of therapeutics to the acidic regions of tumors and sites of inflammation.

  6. Nonoxidative copper nano and fine particles for electroconductive materials

    Microsoft Academic Search

    Tetsu Yonezawa; Hiroki Tsukamoto; Takashi Narushima

    2011-01-01

    Metallic copper nano and fine particles have been successfully prepared by a wet process using a biopolymer as an anti-oxidation reagent. Copper oxide (CuO) and copper sulfate (CuSO4) were the metal sauces used in this study. Hydrazine was used as the reducing reagent in order to obtain copper metal atoms. Uniform sized metallic copper particles were obtained by this process.

  7. Elemental analysis by PIXE and other IBA techniques and their application to source fingerprinting of atmospheric fine particle pollution

    Microsoft Academic Search

    David D. Cohen; Grahame M. Bailey; Ramesh Kondepudi

    1996-01-01

    The PIXE technique in conjunction with PIGME, PESA and RBS has been used to routinely measure over 20 different elements present in fine particle atmospheric samples. PIXE provided data for selected elements from Al to U while the other techniques provided information on elements lighter than Al such as H, C, N, O, F and Na. Detection limits for the

  8. First Measurements of Neutral Atmospheric Cluster and 1–2 nm Particle Number Size Distributions During Nucleation Events

    Microsoft Academic Search

    Jingkun Jiang; Jun Zhao; Modi Chen; Fred L. Eisele; Jacob Scheckman; Brent J. Williams; Chongai Kuang; Peter H. McMurry

    2011-01-01

    Recent observations throughout the atmosphere have shown that nucleation occurs frequently (Kulmala et al. 2004). Modeling studies and observations have shown that nucleated particles contribute significantly to concentrations of cloud condensation nuclei (Spracklen et al. 2008), thereby affecting climate (IPCC 2007). Size-resolved measurements extending down to molecular dimensions can provide information on processes that lead to nucleation and would enable

  9. VIABLE BACTERIAL AEROSOL PARTICLE SIZE DISTRIBUTIONS IN THE MIDSUMMER ATMOSPHERE AT AN ISOLATED LOCATION IN THE HIGH DESERT CHAPARRAL

    EPA Science Inventory

    The viable bacterial particle size distribution in the atmosphere at the Hanford Nuclear Reservation, Richland, WA during two 1-week periods in June 1992, was observed at three intervals during the day (morning, midday and evening) and at three heights (2, 4, and 8 m) above groun...

  10. The origins of liner material in a shaped charge jet particle

    SciTech Connect

    Zernow, L. [Zernow Technical Services, Inc., San Dimas, CA (United States); Chapyak, E.J.; Meyer, K.A. [Los Alamos National Lab., NM (United States); Zernow, R.H. [Applied Research Associates, Inc., Lakewood, CO (United States)

    1992-02-01

    An improved high resolution LaGrangean tracer particle technique (using 198 identified tracer particles arranged as 99 particle pairs) has been used with an Eulerian Code (MESA 2D) to determine the locations in the jet to which liner material flows from various tagged locations in the liner, during the collapse, jet formation and jet stretching process. Time dependent strain and strain rate data has been computed, using the identified particle pairs of LaGrangean tracer particles as linear strain gauges. Sharp radial gradients of strain and strain rate have been found in the jet, with the liner material flowing nearest the jet axis being subjected to the highest strains and strain rates. Liner material from many extended initial locations along the liner can be traced by this method to jet locations corresponding to individual jet particles. The new quantitative data derived is illustrated with selected examples whose interpretation is discussed.

  11. Low-temperature and low atmospheric pressure infrared reflectance spectroscopy of Mars soil analog materials

    NASA Technical Reports Server (NTRS)

    Bishop, Janice L.; Pieters, Carle M.

    1995-01-01

    Infrared reflectance spectra of carefully selected Mars soil analog materials have been measured under low atmospheric pressures and temperatures. Chemically altered montmorillonites containing ferrihydrite and hydrated ferric sulfate complexes are examined, as well as synthetic ferrihydrite and a palagonitic soil from Haleakala, Maui. Reflectance spectra of these analog materials exhibit subtle visible to near-infrared features, which are indicative of nanophase ferric oxides or oxyhydroxides and are similar to features observed in the spectra of the bright regions of Mars. Infrared reflectance spectra of these analogs include hydration features due to structural OH, bound H2O, and adsorbed H2O. The spectral character of these hydration features is highly dependent on the sample environment and on the nature of the H2O/OH in the analogs. The behavior of the hydration features near 1.9 micron, 2.2 micron, 2.7 micron, 3 micron, and 6 microns are reported here in spectra measured under a Marslike atmospheric environment. In spectra of these analogs measured under dry Earth atmospheric conditions the 1.9-micron band depth is 8-17%; this band is much stronger under moist conditions. Under Marslike atmospheric conditions the 1.9-micron feature is broad and barely discernible (1-3% band depth) in spectra of the ferrihydrite and palagonitic soil samples. In comparable spectra of the ferric sulfate-bearing montmorillonite the 1.9-micron feature is also broad, but stronger (6% band depth). In the low atmospheric pressure and temperature spectra of the ferrihydrite-bearing montmorillonite this feature is sharper than the other analogs and relatively stronger (6% band depth). Although the intensity of the 3-micron band is weaker in spectra of each of the analogs when measured under Marslike conditions, the 3-micron band remains a dominant feature and is especially broad in spectra of the ferrihydrite and palagonitic soil. The structural OH features observed in these materials at 2.2-2.3 micron and 2.75 microns remain largely unaffected by the environmental conditions. A shift in the Christiansen feature towards shorter wavelengths has also been observed with decreasing atmospheric pressure and temperature in the midinfrared spectra of these samples.

  12. Low-temperature and low atmospheric pressure infrared reflectance spectroscopy of Mars soil analog materials

    NASA Technical Reports Server (NTRS)

    Bishop, Janice L.; Pieters, Carle M.

    1995-01-01

    Infrared reflectance spectra of carefully selected Mars soil analog materials have been measured under low atmospheric pressures and temperatures. Chemically altered montmorillonites containing ferrihydrite and hydrated ferric sulfate complexes are examined, as well as synthetic ferrihydrate and a palagonitic soil from Haleakala, Maui. Reflectance spectra of these analog materials exhibit subtle visible to near-infrared features, which are indicative of nanophase ferric oxides or oxyhydroxides and are similar to features observed in the spectra of the bright regions of Mars. Infrared reflectance spectra of these analogs include hydration features due to structural OH, bound H2O and adsorbed H2O. The spectal character of these hydration features is highly dependent on the sample environment and on the nature of the H2O/OH in the analogs. The behavior of the hydration features near 1.9 micrometers, 2.2 micrometers, 2.7 micrometers, 3 micrometers, and 6 micrometers are reported here in spetra measured under Marslike atmospheric environment. In spectra of these analogs measured under dry Earth atmospheric conditions the 1.9-micrometer band depth is 8-17%; this band is much stonger under moist conditions. Under Marslike atmospheric conditions the 1.9-micrometer feature is broad and barely discernible (1-3% band depth) in spectra of the ferrihydrite and palagonitic soil samples. In comparable spectra of the ferric sulfate-bearing montmorillonite the 1.9-micrometer feature is also broad, but stronger (6% band depth). In the low atmospheric pressure and temperature spectra of the ferrihydrite-bearing montmorillonite this feature is sharper than the other analogs and relatively stronger (6% band depth). Although the intensity of the 3- micrometer band is weaker in spectra of each of the analogs when measured under Marslike conditions, the 3-micromter band remains a dominant feature and is especially broad in spectra of the ferrihydrite and palagonitic soil. The structural OH features observed in these materials at 2.2-2.3 micrometers and 2.27 micrometers remain largely unaffected by the environmental conditions. A shift in the Christiansen feature towards shorter wavelengths has also been observed with decreasing atmospheric pressure and temperature in the midinfrared spectra of these samples.

  13. Evaluation of bone response to synthetic bone grafting material treated with argon-based atmospheric pressure plasma.

    PubMed

    Beutel, Bryan G; Danna, Natalie R; Gangolli, Riddhi; Granato, Rodrigo; Manne, Lakshmiprada; Tovar, Nick; Coelho, Paulo G

    2014-12-01

    Bone graft materials are utilized to stimulate healing of bone defects or enhance osseointegration of implants. In order to augment these capabilities, various surface modification techniques, including atmospheric pressure plasma (APP) surface treatment, have been developed. This in vivo study sought to assess the effect of APP surface treatment on degradation and osseointegration of Synthograft™, a beta-tricalcium phosphate (?-TCP) synthetic bone graft. The experimental (APP-treated) grafts were subjected to APP treatment with argon for a period of 60s. Physicochemical characterization was performed by environmental scanning electron microscopy, surface energy (SE), and x-ray photoelectron spectroscopy analyses both before and after APP treatment. Two APP-treated and two untreated grafts were surgically implanted into four critical-size calvarial defects in each of ten New Zealand white rabbits. The defect samples were explanted after four weeks, underwent histological analysis, and the percentages of bone, soft tissue, and remaining graft material were quantified by image thresholding. Material characterization showed no differences in particle surface morphology and that the APP-treated group presented significantly higher SE along with higher amounts of the base material chemical elements on it surface. Review of defect composition showed that APP treatment did not increase bone formation or reduce the amount of soft tissue filling the defect when compared to untreated material. Histologic cross-sections demonstrated osteoblastic cell lines, osteoid deposition, and neovascularization in both groups. Ultimately, argon-based APP treatment did not enhance the osseointegration or degradation of the ?-TCP graft. Future investigations should evaluate the utility of gases other than argon to enhance osseointegration through APP treatment. PMID:25491854

  14. Chemistry of atmospheric aerosol particles and their resulting warm cloud-nucleation properties

    E-print Network

    Moore, Meagan Julia Kerry

    2011-01-01

    particle sizer (APS) size distributions of the bubbled particles for the NaClparticle sizer (APS) size distributions of the bubbled particles for the NaClparticle sizer (APS) size distributions of the bubbled particles for the NaCl

  15. Acoustic properties and durability of liner materials at non-standard atmospheric conditions

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Gaeta, R. J., Jr.; Hsu, J. S.

    1994-01-01

    This report documents the results of an experimental study on how acoustic properties of certain absorbing liner materials are affected by nonstandard atmospheric conditions. This study was motivated by the need to assess risks associated with incorporating acoustic testing capability in wind tunnels with semicryogenic high Reynolds number aerodynamic and/or low pressure capabilities. The study consisted of three phases: 1) measurement of acoustic properties of selected liner materials at subatmospheric pressure conditions, 2) periodic cold soak and high pressure exposure of liner materials for 250 cycles, and 3) determination of the effect of periodic cold soak on the acoustic properties of the liner materials at subatmospheric conditions and the effect on mechanical resiliency. The selected liner materials were Pyrell foam, Fiberglass, and Kevlar. A vacuum facility was used to create the subatmospheric environment in which an impedance tube was placed to measure acoustic properties of the test materials. An automated cryogenic cooling system was used to simulate periodic cold soak and high pressure exposure. It was found that lower ambient pressure reduced the absorption effectiveness of the liner materials to varying degrees. Also no significant change in the acoustic properties occurred after the periodic cold soak. Furthermore, mechanical resiliency tests indicated no noticeable change.

  16. Models and methods for automated material identification in hyperspectral imagery acquired under unknown illumination and atmospheric conditions

    Microsoft Academic Search

    Glenn Healey; David Slater

    1999-01-01

    The spectral radiance measured by an airborne imaging spectrometer for a material on the Earth's surface depends strongly on the illumination incident of the material and the atmospheric conditions. This dependence has limited the success of material-identification algorithms that rely on hyperspectral image data without associated ground-truth information. In this paper, the authors use a comprehensive physical model to show

  17. Functionalised carboxylic acids in atmospheric particles: An annual cycle revealing seasonal trends and possible sources

    NASA Astrophysics Data System (ADS)

    Teich, Monique; van Pinxteren, Dominik; Herrmann, Hartmut

    2013-04-01

    Carboxylic acids represent a major fraction of the water soluble organic carbon (WSOC) in atmospheric particles. Among the particle phase carboxylic acids, straight-chain monocarboxylic acids (MCA) and dicarboxylic acids (DCA) with 2-10 carbon atoms have extensively been studied in the past. However, only a few studies exist dealing with functionalised carboxylic acids, i.e. having additional hydroxyl-, oxo- or nitro-groups. Regarding atmospheric chemistry, these functionalised carboxylic acids are of particular interest as they are supposed to be formed during atmospheric oxidation processes, e.g. through radical reactions. Therefore they can provide insights into the tropospheric multiphase chemistry. During this work 28 carboxylic acids (4 functionalised aliphatic MCAs, 5 aromatic MCAs, 3 nitroaromatic MCAs, 6 aliphatic DCAs, 6 functionalised aliphatic DCAs, 4 aromatic DCAs) were quantitatively determined in 256 filter samples taken at the rural research station Melpitz (Saxony, Germany) with a PM10 Digitel DHA-80 filter sampler. All samples were taken in 2010 covering a whole annual cycle. The resulting dataset was examined for a possible seasonal dependency of the acid concentrations. Furthermore the influence of the air mass origin on the acid concentrations was studied based on a simple two-sector classification (western or eastern sector) using a back trajectory analysis. Regarding the annual average, adipic acid was found to be the most abundant compound with a mean concentration of 7.8 ng m-3 followed by 4-oxopimelic acid with 6.1 ng m-3. The sum of all acid concentrations showed two maxima during the seasonal cycle; one in summer and one in winter, whereas the highest overall acid concentrations were found in summer. In general the target acids could be divided into two different groups, where one group has its maximum concentration in summer and the other group during winter. The first group contains all investigated aliphatic mono- and dicarboxylic acids. The high concentrations in summer could lead to the conclusion that these acids are mostly formed during photochemical processes in the atmosphere. However, the concentrations in autumn were often exceeded by the ones in winter. Therefore probably other sources beside photochemical processes have to be considered. The second group consists of aromatic compounds. Because of the high concentrations in winter it can be concluded that photochemical formation plays a minor role and primary emission sources e.g., wood combustion are likely. Further evidence in determining sources of the carboxylic acids could be obtained from the air mass origin. In general, air masses transported from East have a more anthropogenic influence than the air mass inflow from West. For all aromatic carboxylic acids higher concentrations were determined during eastern inflow, indicating anthropogenic sources. This presumption is supported by high correlations with the elemental carbon (EC). Regarding the aliphatic carboxylic there is one group with higher concentrations when the air mass is transported from West and one with higher concentrations when air mass is transported from East. In summary the findings of this study reveal a clear difference in the seasonal trends of the single target acids indicating a variety of different sources.

  18. Autofluorescence of atmospheric bioaerosols - Biological standard particles and the influence of environmental conditions

    NASA Astrophysics Data System (ADS)

    Pöhlker, Christopher; Huffman, J. Alex; Förster, Jan-David; Pöschl, Ulrich

    2013-04-01

    Primary biological aerosol particles (PBAP) such as pollen, fungal spores, bacteria, biogenic polymers and debris from larger organisms are known to influence atmospheric chemistry and physics, the biosphere and public health. PBAP can account for up to ~30% of fine and up to ~70% of coarse particulate matter in urban, rural and pristine environment and are released with estimated emission rates of up to ~1000 Tg/a [1]. Continuous measurements of the abundance, variability and diversity of PBAP have been difficult until recently, however. The application of on-line instruments able to detect autofluorescence from biological particles in real-time has been a promising development for the measurement of PBAP concentrations and fluxes in different environments [2,3]. The detected fluorescent biological aerosol particles (FBAP) can be regarded as a subset of PBAP, although the exact relationship between PBAP and FBAP is still being investigated. Autofluorescence of FBAP is usually a superposition of fluorescence from a mixture of individual fluorescent molecules (fluorophores). Numerous biogenic fluorophores such as amino acids (e.g., tryptophan, tyrosine), coenzymes (e.g., NAD(P)H, riboflavin) and biopolymers (e.g., cellulose) emit fluorescent light due to heterocyclic aromatic rings or conjugated double bonds within their molecular structures. The tryptophan emission peak is a common feature of most bioparticles because the amino acid is a constituent of many proteins and peptides. The influence of the coenzymes NAD(P)H and riboflavin on the autofluorescence of bacteria can be regarded as an indicator for bacterial metabolism and has been utilized to discriminate between viable and non-viable organisms [4]. However, very little information is available about other essential biofluorophores in fungal spores and pollen. In order to better understand the autofluorescence behavior of FBAP, we have used fluorescence spectroscopy and fluorescence microscopy to analyze standard bioparticles (pollen, fungal spores, and bacteria) as well as atmospherically relevant chemical substances. We addressed the sensitivity and selectivity of autofluorescence based online techniques. Moreover, we investigated the influence of environmental conditions, such as relative humidity and oxidizing agents in the atmosphere, on the autofluorescence signature of standard bioparticles. Our results will support the molecular understanding and quantitative interpretation of data obtained by real-time FBAP instrumentation [5,6]. [1] Elbert, W., Taylor, P. E., Andreae, M. O., & Pöschl, U. (2007). Atmos. Chem. Phys., 7, 4569-4588. [2] Huffman, J. A., Treutlein, B., & Pöschl, U. (2010). Atmos. Chem. Phys., 10, 3215-3233. [3] Pöschl, U., et al. (2010). Science, 329, 1513-1516. [4] Lakowicz, J., Principles of fluorescence spectroscopy, Plenum publishers, New York, 1999. [5] Pöhlker, C., Huffman, J. A., & Pöschl, U., (2012). Atmos. Meas. Tech., 5, 37-71. [6] Pöhlker, C., Huffman, J. A., Förster J.-D., & Pöschl, U., (2012) in preparation.

  19. A simplified approach for solving coagulation–diffusion equation to estimate atmospheric background particle number loading factors contributed by emissions from localized sources

    Microsoft Academic Search

    S. Anand; Y. S. Mayya

    2011-01-01

    Coagulation and condensation\\/evaporation combined with atmospheric dispersion are the main processes responsible for the evolution of aerosol particle size distributions and number concentrations emitted from localized sources. A crucial question is: what fraction of freshly emitted particles survive intra-coagulation effect to persist in the atmosphere and become available for further interaction with background aerosols?. The difficulty in estimating this quantity,

  20. Thermodynamic analysis of chemical stability of ceramic materials in hydrogen-containing atmospheres at high temperatures

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1990-01-01

    The chemical stability of several ceramic materials in hydrogen-containing environments was analyzed with thermodynamic considerations in mind. Equilibrium calculations were made as a function of temperature, moisture content, and total system pressure. The following ceramic materials were considered in this study: SiC, Si3N4, SiO2, Al2O3, mullite, ZrO2, Y2O3, CaO, MgO, BeO, TiB2, TiC, HfC, and ZrC. On the basis of purely thermodynamic arguments, upper temperature limits are suggested for each material for long-term use in H2-containing atmospheres.

  1. The Exploration Atmospheres Working Group's Report on Space Radiation Shielding Materials

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.; Thibeault, S. A.

    2006-01-01

    This part of Exploration Atmospheres Working Group analyses focuses on the potential use of nonmetallic composites as the interior walls and structural elements exposed to the atmosphere of the spacecraft or habitat. The primary drive to consider nonmetallic, polymer-based composites as an alternative to aluminum structure is due to their superior radiation shielding properties. But as is shown in this analysis, these composites can also be made to combine superior mechanical properties with superior shielding properties. In addition, these composites can be made safe; i.e., with regard to flammability and toxicity, as well as "smart"; i.e., embedded with sensors for the continuous monitoring of material health and conditions. The analysis main conclusions are that (1) smart polymer-based composites are an enabling technology for safe and reliable exploration missions, and (2) an adaptive, synergetic systems approach is required to meet the missions requirements from structure, properties, and processes to crew health and protection for exploration missions.

  2. 49 CFR 195.581 - Which pipelines must I protect against atmospheric corrosion and what coating material may I use?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Which pipelines must I protect against atmospheric corrosion...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF...

  3. 49 CFR 195.581 - Which pipelines must I protect against atmospheric corrosion and what coating material may I use?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Which pipelines must I protect against atmospheric corrosion...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF...

  4. 49 CFR 195.581 - Which pipelines must I protect against atmospheric corrosion and what coating material may I use?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Which pipelines must I protect against atmospheric corrosion...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF...

  5. 49 CFR 195.581 - Which pipelines must I protect against atmospheric corrosion and what coating material may I use?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Which pipelines must I protect against atmospheric corrosion...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF...

  6. ACIDIC DEPOSITION AND THE CORROSION AND DETERIORATION OF MATERIALS IN THE ATMOSPHERE: A BIBLIOGRAPHY, 1880-1982

    EPA Science Inventory

    The bibliography contains more than 1300 article citations and abstracts on the effects of acidic deposition, air pollutants, and biological and meteorological factors on the corrosion and deterioration of materials in the atmosphere. The listing includes citations for the years ...

  7. Laboratory and Field Testing of an Automated Atmospheric Particle-Bound Reactive Oxygen Species Sampling-Analysis System

    PubMed Central

    Wang, Yungang; Hopke, Philip K.; Sun, Liping; Chalupa, David C.; Utell, Mark J.

    2011-01-01

    In this study, various laboratory and field tests were performed to develop an effective automated particle-bound ROS sampling-analysis system. The system uses 2? 7?-dichlorofluorescin (DCFH) fluorescence method as a nonspecific, general indicator of the particle-bound ROS. A sharp-cut cyclone and a particle-into-liquid sampler (PILS) were used to collect PM2.5 atmospheric particles into slurry produced by a DCFH-HRP solution. The laboratory results show that the DCFH and H2O2 standard solutions could be kept at room temperature for at least three and eight days, respectively. The field test in Rochester, NY, shows that the average ROS concentration was 8.3 ± 2.2 nmol of equivalent H2O2?m?3 of air. The ROS concentrations were observed to be greater after foggy conditions. This study demonstrates the first practical automated sampling-analysis system to measure this ambient particle component. PMID:21577270

  8. Materials performance in the atmospheric fluidized-bed cogeneration air heater experiment

    SciTech Connect

    Natesan, K.; Podolski, W.; Wang, D.Y.; Teats, F.G. [Argonne National Lab., IL (United States); Gerritsen, W.; Stewart, A.; Robinson, K. [Rockwell International Corp., Canoga Park, CA (United States)

    1991-02-01

    The Atmospheric Fluidized-Bed Cogeneration Air Heater Experiment (ACAHE) sponsored by the US Department of Energy (DOE) was initiated to assess the performance of various heat-exchanger materials to be used in fluidized-bed combustion air heater systems. Westinghouse Electric Corporation, through subcontracts with Babcock & Wilcox, Foster Wheeler, and ABB Combustion Engineering Systems, prepared specifications and hardware for the ACAHE tests. Argonne National Laboratory contracted with Rockwell International to conduct tests in the DOE atmospheric fluidized-bed combustion facility. This report presents an overview of the project, a description of the facility and the test hardware, the test operating conditions, a summary of the operation, and the results of analyzing specimens from several uncooled and cooled probes exposed in the facility. Extensive microstructural analyses of the base alloys, claddings, coatings, and weldments were performed on specimens exposed in several probes for different lengths of time. Alloy penetration data were determined for several of the materials as a function of specimen orientation and the exposure location in the combustor. Finally, the data were compared with earlier laboratory test data, and the long-term performance of candidate materials for air-heater applications was assessed.

  9. Materials performance in the atmospheric fluidized-bed cogeneration air heater experiment

    SciTech Connect

    Natesan, K.; Podolski, W.; Wang, D.Y.; Teats, F.G. (Argonne National Lab., IL (United States)); Gerritsen, W.; Stewart, A.; Robinson, K. (Rockwell International Corp., Canoga Park, CA (United States))

    1991-02-01

    The Atmospheric Fluidized-Bed Cogeneration Air Heater Experiment (ACAHE) sponsored by the US Department of Energy (DOE) was initiated to assess the performance of various heat-exchanger materials to be used in fluidized-bed combustion air heater systems. Westinghouse Electric Corporation, through subcontracts with Babcock Wilcox, Foster Wheeler, and ABB Combustion Engineering Systems, prepared specifications and hardware for the ACAHE tests. Argonne National Laboratory contracted with Rockwell International to conduct tests in the DOE atmospheric fluidized-bed combustion facility. This report presents an overview of the project, a description of the facility and the test hardware, the test operating conditions, a summary of the operation, and the results of analyzing specimens from several uncooled and cooled probes exposed in the facility. Extensive microstructural analyses of the base alloys, claddings, coatings, and weldments were performed on specimens exposed in several probes for different lengths of time. Alloy penetration data were determined for several of the materials as a function of specimen orientation and the exposure location in the combustor. Finally, the data were compared with earlier laboratory test data, and the long-term performance of candidate materials for air-heater applications was assessed.

  10. Atmospheric ultrafine particles promote vascular calcification via the NF-?B signaling pathway

    PubMed Central

    Li, Rongsong; Mittelstein, David; Kam, Winnie; Pakbin, Payam; Du, Yunfeng; Tintut, Yin; Navab, Mohamad; Sioutas, Constantinos

    2013-01-01

    Exposure to atmospheric fine particulate matter (PM2.5) is a modifiable risk factor of cardiovascular disease. Ultrafine particles (UFP, diameter <0.1 ?m), a subfraction of PM2.5, promote vascular oxidative stress and inflammatory responses. Epidemiologic studies suggest that PM exposure promotes vascular calcification. Here, we assessed whether UFP exposure promotes vascular calcification via NF-?B signaling. UFP exposure at 50 ?g/ml increased alkaline phosphatase (ALP) activity by 4.4 ± 0.2-fold on day 3 (n = 3, P < 0.001) and matrix calcification by 3.5 ± 1.7-fold on day 10 (n = 4, P < 0.05) in calcifying vascular cells (CVC), a subpopulation of vascular smooth muscle cells with osteoblastic potential. Treatment of CVC with conditioned media derived from UFP-treated macrophages (UFP-CM) also led to an increase in ALP activities and matrix calcification. Furthermore, both UFP and UFP-CM significantly increased NF-?B activity, and cotreatment with an NF-?B inhibitor, JSH23, attenuated both UFP- and UFP-CM-induced ALP activity and calcification. When low-density lipoprotein receptor-null mice were exposed to UFP at 359.5 ?g/m3 for 10 wk, NF-?B activation and vascular calcification were detected in the regions of aortic roots compared with control filtered air-exposed mice. These findings suggest that UFP promotes vascular calcification via activating NF-?B signaling. PMID:23242187

  11. Levoglucosan, a tracer for cellulose in biomass burning and atmospheric particles

    NASA Astrophysics Data System (ADS)

    Simoneit, B. R. T.; Schauer, J. J.; Nolte, C. G.; Oros, D. R.; Elias, V. O.; Fraser, M. P.; Rogge, W. F.; Cass, G. R.

    The major organic components of smoke particles from biomass burning are monosaccharide derivatives from the breakdown of cellulose, accompanied by generally lesser amounts of straight-chain, aliphatic and oxygenated compounds and terpenoids from vegetation waxes, resins/gums, and other biopolymers. Levoglucosan and the related degradation products from cellulose can be utilized as specific and general indicator compounds for the presence of emissions from biomass burning in samples of atmospheric fine particulate matter. This enables the potential tracking of such emissions on a global basis. There are other compounds (e.g. amyrones, friedelin, dehydroabietic acid, and thermal derivatives from terpenoids and from lignin—syringaldehyde, vanillin, syringic acid, vanillic acid), which are additional key indicators in smoke from burning of biomass specific to the type of biomass fuel. The monosaccharide derivatives (e.g. levoglucosan) are proposed as specific indicators for cellulose in biomass burning emissions. Levoglucosan is emitted at such high concentrations that it can be detected at considerable distances from the original combustion source.

  12. Identifying organic aerosol sources by comparing functional group composition in chamber and atmospheric particles

    PubMed Central

    Russell, Lynn M.; Bahadur, Ranjit; Ziemann, Paul J.

    2011-01-01

    Measurements of submicron particles by Fourier transform infrared spectroscopy in 14 campaigns in North America, Asia, South America, and Europe were used to identify characteristic organic functional group compositions of fuel combustion, terrestrial vegetation, and ocean bubble bursting sources, each of which often accounts for more than a third of organic mass (OM), and some of which is secondary organic aerosol (SOA) from gas-phase precursors. The majority of the OM consists of alkane, carboxylic acid, hydroxyl, and carbonyl groups. The organic functional groups formed from combustion and vegetation emissions are similar to the secondary products identified in chamber studies. The near absence of carbonyl groups in the observed SOA associated with combustion is consistent with alkane rather than aromatic precursors, and the absence of organonitrate groups can be explained by their hydrolysis in humid ambient conditions. The remote forest observations have ratios of carboxylic acid, organic hydroxyl, and nonacid carbonyl groups similar to those observed for isoprene and monoterpene chamber studies, but in biogenic aerosols transported downwind of urban areas the formation of esters replaces the acid and hydroxyl groups and leaves only nonacid carbonyl groups. The carbonyl groups in SOA associated with vegetation emissions provides striking evidence for the mechanism of esterification as the pathway for possible oligomerization reactions in the atmosphere. Forest fires include biogenic emissions that produce SOA with organic components similar to isoprene and monoterpene chamber studies, also resulting in nonacid carbonyl groups in SOA. PMID:21317360

  13. Materials, methods and devices to detect and quantify water vapor concentrations in an atmosphere

    DOEpatents

    Allendorf, Mark D; Robinson, Alex L

    2014-12-09

    We have demonstrated that a surface acoustic wave (SAW) sensor coated with a nanoporous framework material (NFM) film can perform ultrasensitive water vapor detection at concentrations in air from 0.05 to 12,000 ppmv at 1 atmosphere pressure. The method is extendable to other MEMS-based sensors, such as microcantilevers, or to quartz crystal microbalance sensors. We identify a specific NFM that provides high sensitivity and selectivity to water vapor. However, our approach is generalizable to detection of other species using NFM to provide sensitivity and selectivity.

  14. Material degradation and particle formation under transient thermal loads

    Microsoft Academic Search

    J. Linke; M. Akiba; R. Duwe; A. Lodato; H.-J. Penkalla; M. Rodig; K. Schopflin

    2001-01-01

    Carbon-based materials and metals have been exposed to fusion relevant thermal loads in an electron beam test facility to simulate off-normal plasma conditions such as disruptions or vertical displacement events (VDEs). The erosion process in carbon-based materials is dominated by brittle destruction, a process which is associated with the formation of carbon dust; this process becomes essential at a threshold

  15. Chemistry of atmospheric aerosol particles and their resulting warm cloud-nucleation properties

    E-print Network

    Moore, Meagan Julia Kerry

    2011-01-01

    Atmospheric Chemistry and Physics, 10 (6363- Chang, R.Y. -Chang, Evidence of mineral dust altering cloud microphysics and precipitation, Atmospheric ChemistryChemistry and Physics, 10, 5165-5178, 2010. Chang, R.Y. -

  16. Distribution of particles creating "smart" material Mathematics Department, Kansas State University,

    E-print Network

    " materials, wave scattering, distribution of small particles, inverse scat- tering. 1 Introduction Let D0 R3()? Here is the unit vector, the direction of the scattered field, and the dependence of the scat- tering

  17. PLASMA WINDOW FOR VACUUM - ATMOSPHERE INTERFACE AND FOCUSING LENS OF SOURCES FOR NON-VACUUM MATERIAL MODIFICATION.

    SciTech Connect

    HERSHCOVITCH,A.

    1997-09-07

    Material modifications by ion implantation, dry etching, and micro-fabrication are widely used technologies, all of which are performed in vacuum, since ion beams at energies used in these applications are completely attenuated by foils or by long differentially pumped sections, which ate currently used to interface between vacuum and atmosphere. A novel plasma window, which utilizes a short arc for vacuum-atmosphere interface has been developed. This window provides for sufficient vacuum atmosphere separation, as well as for ion beam propagation through it, thus facilitating non-vacuum ion material modification.

  18. Change in surface of polymer materials upon irradiation of accelerated micro-particles

    Microsoft Academic Search

    Hisaaki Kudo; Masashi Tadokoro; Shintaro Narita; Leo Matsuoka; Yusa Muroya; Yosuke Katsumura

    2005-01-01

    As a new method of use of a particle accelerator (ionizing radiation generator), we irradiated accelerated micro-particles of silver (Ag) onto polymer materials such as polyimides, glass, ceramics and semi-conductors. The particles can be generated at a Van de Graaff electrostatic accelerator operating at 1–3MV. The velocity was around 1–10km\\/s, size of diameter was about 1–10?m and charge was about

  19. Why like-charged particles of dielectric materials can be attracted to one another.

    PubMed

    Stace, Anthony J; Boatwright, Adrian L; Khachatourian, Armik; Bichoutskaia, Elena

    2011-02-01

    Calculations of surface charge density provide evidence of the physical effects responsible for particles of a dielectric material carrying the same sign of charge being attracted to one another. The results show that attraction requires a mutual polarisation of charge leading to regions of negative and positive surface density close to the point where the particles make contact. These results emphasise the significance of using charged particle models where the surface charge is non-stationary. PMID:21131001

  20. Particle Size Effects on Thermal Decomposition of Energetic Material

    Microsoft Academic Search

    M. Fathollahi; S. M. Pourmortazavi; S. G. Hosseini

    2007-01-01

    This work refers to a study of the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) by differential scanning calorimetry (DSC) under nonisothermal conditions, with heating rates from 5 to 20°C min. The influence of the particle size in the thermal decomposition of HMX was verified. The activation energy for the decomposition of each sample was calculated using the peak temperature shift methods, proposed

  1. Dynamics of Granular Materials and Particle-Laden Flows

    SciTech Connect

    Swinney, Harry L.

    2007-07-11

    Rapid granular flows and particle-laden flows were studied in laboratory experiments, molecular dynamics simulations, and simulations of continuum equations. The research demonstrated that the inclusion of friction is crucial in realistic modeling of granular flows; hence extensive previous analyses and simulations by many researchers for frictionless particles must be reconsidered in the light of our work. We also made the first detailed comparison between experiment and the predictions of continuum theory for granular media (hydrodynamic equations). We found that shock waves easily form in granular flows since the speed of sound waves (pressure fluctuations) in a granular gas is small, typically 10 cm, while flow velocities are easily an order of magnitude larger. Our measurements on vertically oscillating granular layers led to the development of a novel technique for continuously separating particles of different sizes. Our study of craters formed by the impact of a projectile in a granular medium showed, surprisingly, that the time taken for a projectile to come to a rest in the granular layer is independent of the projectile’s impact energy. Another study supported by this grant examined a vertically oscillating layer of a mixture of cornstarch and water. The discovery of stable holes in the mixture was reported widely in the popular press, e.g., Science News [15 May 2004], “Imaging poking a liquid to create holes that persist like the holes in Swiss cheese. Incredible as that might sound, a group of scientists has done it.” Further experiments on glass spheres in an aqueous solution yielded the same holey fluid phenomenon, supporting our conjecture that such holes may occur in dense concentrations of particles in solution in industrial applications.

  2. Thermoelectric figure of merit of a material consisting of semiconductor or metal particles

    SciTech Connect

    Kharlamov, V. F., E-mail: kharl@ostu.ru [Orel State Technical University (Russian Federation)

    2013-07-15

    It is found that the dimensionless thermoelectric figure of merit of a material consisting of a large number of ball-shaped semiconductor or metal particles can be much more than unity. The introduction of an insulator into the space between the particles is shown to sharply increase the power of the converter of heat energy into electric current energy.

  3. Why like-charged particles of dielectric materials can be attracted to one another

    Microsoft Academic Search

    Anthony J. Stace; Adrian L. Boatwright; Armik Khachatourian; Elena Bichoutskaia

    2011-01-01

    Calculations of surface charge density provide evidence of the physical effects responsible for particles of a dielectric material carrying the same sign of charge being attracted to one another. The results show that attraction requires a mutual polarisation of charge leading to regions of negative and positive surface density close to the point where the particles make contact. These results

  4. Electrostatic analysis of the interactions between charged particles of dielectric materials

    Microsoft Academic Search

    Elena Bichoutskaia; Adrian L. Boatwright; Armik Khachatourian; Anthony J. Stace

    2010-01-01

    An understanding of the electrostatic interactions that exist between charged particles of dielectric materials has applications that span much of chemistry, physics, biology, and engineering. Areas of interest include cloud formation, ink-jet printing, and the stability of emulsions. A general solution to the problem of calculating electrostatic interactions between charged dielectric particles is presented. The solution converges very rapidly for

  5. TCT characterization of different semiconductor materials for particle detection

    NASA Astrophysics Data System (ADS)

    Fink, J.; Lodomez, P.; Krüger, H.; Pernegger, H.; Weilhammer, P.; Wermes, N.

    2006-09-01

    The development of digital semiconductor based X-ray detectors necessitates a detailed understanding of the applied sensor material. Under this premise a broad-band transient current technique (TCT) setup has been developed and used to characterize different semiconductors. The measurements are based on the generation of electrical charges within the sensor material and the subsequent time-resolved analysis of the charge carrier movement. From the recorded current pulses the charge collection efficiency, the charge carrier mobility and the electric field profile have been extracted. The examined materials are silicon p in n diodes, ohmic and Schottky contacted CdTe detectors, CdZnTe (CZT) crystals with Schottky contacts as well as two single-crystal CVD-diamonds.

  6. Angular particle impingement studies of thermoplastic materials at normal incidence

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Buckley, D. H.

    1985-01-01

    Scanning electron microscope studies were conducted to characterize the erosion resistance of polymethyl methacrylate (PMMA), polycarbonate (PC), polytetrafluorethylene (PTFE), and ultra-high-molecular-weight polyethylene (UHMWPE). Erosion was caused by a jet of angular microparticles of crushed glass at normal incidence. Material built up above the original surface on all of the materials. As erosion progressed, this buildup disappeared. UHMWPE was the most resistant material and PMMA the least. The most favorable properties for high erosion resistance were high values of ultimate elongation, maximum service temperature, and strain energy and a low value of the modulus of elasticity. Erosion-rate-versus-time curves of PC and PTFE exhibited incubation, acceleration, and steady-state periods. PMMA also exhibited a deceleration period, and an incubation period with deposition was observed for UHMWPE.

  7. The thermal performance of fuel matrix material in a CO2 atmosphere

    NASA Astrophysics Data System (ADS)

    Turner, J. D.; Schmidt, M. J. S.; Abram, T. J.

    2013-11-01

    The thermal oxidation performance of a semi-graphitic fuel matrix-material has been compared to two grades of nuclear graphite between 600 °C and 1200 °C in flowing CO2. Fuel matrix material is used to produce compacts or pebbles containing TRISO coated particle fuel for High Temperature Reactors (HTRs). The A3-27 fuel matrix-material grade was compared to NBG-18 and Gilsocarbon nuclear graphite grades. At 1200 °C temperatures A3-27 appears to be more reactive than NBG-18, but less so than Gilsocarbon. At 600 °C the oxidation rate of A3-27 is comparable to that of NBG-18, but both are significantly higher than that of Gilsocarbon. It is concluded that the comparable thermal oxidation behaviour of graphite and fuel-matrix material suggests that operating temperatures in a CO2 cooled reactor fuelled with TRISO coated particle fuel would not need to be reduced below those considered acceptable for the use of nuclear graphite.

  8. Setting threshold values of particle sizes for determination of the appropriate dispersion/deposition model during various atmospheric stability conditions

    NASA Astrophysics Data System (ADS)

    Mandel, Alon; Stern, Eli; Ullmann, Amos; Brauner, Neima

    2015-03-01

    An approach is suggested for the estimation of air borne critical particle diameter that determines the dominant removal mechanism from atmospheric dispersion of plumes for six main Pasquill-Gifford meteorological stability conditions. A methodology was developed to apply in rural regions since relevant meteorological input data have been developed mainly for such areas. Our critical diameter methodology refines the commonly accepted "50 micron diameter", considered as a border value above which gravitational settling is dominant and below which, turbulent dispersion is expected to prevail. The interrelationships of particle release heights and downwind deposition distances (for various stability conditions) as well as particle sizes and densities are implemented in the turbulent dispersion and gravitational settling estimations, in order to determine the dominant mechanism for particles reaching the ground following their releases from various heights.

  9. Assembling and properties of the polymer-particle nanostructured materials

    Microsoft Academic Search

    Roman Sheparovych

    2010-01-01

    Complementary properties of the soft and hard matter explain its common encounter in many natural and manmade applications. A combination of flexible organic macromolecules and hard mineral clusters results in new materials far advantageous than its constituents alone. In this work we study assembling of colloidal nanocrystals and polymers into complex nanostructures. Magnetism, surface wettability and adhesion comprise properties of

  10. Optical characterization of solid particle solar central receiver materials

    Microsoft Academic Search

    K. A. Stahl; J. W. Griffin; B. S. Matson; R. B. Pettit

    1986-01-01

    The angular scattering properties and scattering and absorption components of the extinction coefficient have been measured for Master Beads, an iron-doped AlâOâ spheroid manufactured by Norton Chemical Co., Worcester, MA. This material, commonly used as a proppant in oil well drilling operations, exhibits good optical absorption properties over the solar insolation spectrum, and favorable thermal and mechanical properties for temperatures

  11. Organic particulate material levels in the atmosphere: Conditions favoring sensitivity to varying relative humidity and temperature

    PubMed Central

    Pankow, James F.

    2010-01-01

    This study examines the sensitivity in predicted levels of atmospheric organic particulate matter (Mo, ?g m-3) as those levels may potentially be affected by changes in relative humidity and temperature. In a given system, for each partitioning compound, fg and fp represent the gaseous and particulate fractions (fg + fp = 1). Sensitivity in the Mo levels becomes dampened as the compounds contributing significantly to Mo are increasingly found in the particle phase (fp ? 1). Thus, although local maxima in sensitivity can be encountered as Mo levels increase, because as Mo increases each fp ? 1, then increasing Mo levels generally tend to reduce sensitivity in Mo levels to changes in relative humidity and temperature. Experiments designed to elucidate the potential magnitudes of the effects of relative humidity and temperature on Mo levels must be carried out at Mo levels that are relevant for the ambient atmosphere: The fp values for the important partitioning compounds must not be elevated above ambient-relevant values. Systems in which Mo levels are low (e.g., 1–2 ?g m-3) and/or composed of unaged secondary organic aerosol are the ones most likely to show sensitivity to changing relative humidity and temperature. Results from two published chamber studies are examined in the above regard: [Warren B, et al. (2009) Atmos Environ 43:1789–1795] and [Prisle NL, et al. (2010) Geophys Res Lett 37:L01802]. PMID:20368456

  12. Atmospheres

    NASA Astrophysics Data System (ADS)

    Bott, June; Yin, Hongbin; Sridhar, Seetharaman

    2014-12-01

    When high Al containing Fe alloys such as TRIP steels are exposed to atmospheres that contain N2 during re-heating, sub-surface nitrides form and these can be detrimental to mechanical properties. Nitride precipitation can be controlled by minimizing the access of the gaseous atmosphere to the metal surface, which can be achieved by a rapid growth of a continuous and adherent surface scale. This investigation utilizes a Au-image furnace attached to a confocal scanning microscope to simulate the annealing temperature vs time while Fe-Al alloys (with Al contents varying from 1 to 8 wt pct) are exposed to a O2-N2 atm with 10-6 atm O2. The heating times of 1, 10, and 100 minutes to the isothermal temperature of 1558 K (1285 °C) were used. It was found that fewer sub-surface nitride precipitates formed when the heating time was lowered and when Al content in the samples was increased. In the 8 wt pct samples, no internal nitride precipitates were present regardless of heating time. In the 3 and 5 wt pct samples, internal nitride precipitates were nearly more or less absent at heating times less than 10 minutes. The decrease in internal precipitates was governed by the evolving structure of the external oxide-scale. At low heating rates and/or low Al contents, significant Fe-oxide patches formed and these appeared to allow for ingress of gaseous N2. For the slow heating rates, ingress could have happened during the longer time spent in lower temperatures where non-protective alumina was present. As Al content in the alloy was increased, the external scale was Al2O3 and/or FeAl2O4 and more continuous and consequently hindered the N2 from accessing the metal surface. Increasing the Al content in the alloy had the effect of promoting the outward diffusion of Al in the alloy and thereby assisting the formation of the continuous external layer of Al2O3 and/or FeAl2O4.

  13. Interactions of mineral dust with pollution and clouds: An individual-particle TEM study of atmospheric aerosol from Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Pósfai, Mihály; Axisa, Duncan; Tompa, Éva; Freney, Evelyn; Bruintjes, Roelof; Buseck, Peter R.

    2013-03-01

    Aerosol particles from desert dust interact with clouds and influence climate on regional and global scales. The Riyadh (Saudi Arabia) aerosol campaign was initiated to study the effects of dust particles on cloud droplet nucleation and cloud properties. Here we report the results of individual-particle studies of samples that were collected from an aircraft in April 2007. We used analytical transmission electron microscopy, including energy-dispersive X-ray spectrometry, electron diffraction, and imaging techniques for the morphological, chemical, and structural characterization of the particles. Dust storms and regional background conditions were encountered during four days of sampling. Under dusty conditions, the coarse (supermicrometer) fraction resembles freshly crushed rock. The particles are almost exclusively mineral dust grains and include common rock-forming minerals, among which clay minerals, particularly smectites, are most abundant. Unaltered calcite grains also occur, indicating no significant atmospheric processing. The particles have no visible coatings but some contain traces of sulfur. The fine (submicrometer) fraction is dominated by particles of anthropogenic origin, primarily ammonium sulfate (with variable organic coating and some with soot inclusions) and combustion-derived particles (mostly soot). In addition, submicrometer, iron-bearing clay particles also occur, many of which are internally mixed with ammonium sulfate, soot, or both. We studied the relationships between the properties of the aerosol and the droplet microphysics of cumulus clouds that formed above the aerosol layer. Under dusty conditions, when a large concentration of coarse-fraction mineral particles was in the aerosol, cloud drop concentrations were lower and droplet diameters larger than under regional background conditions, when the aerosol was dominated by submicrometer sulfate particles.

  14. The simulation of particulate materials packing using a particle suspension model

    Microsoft Academic Search

    Konstantin Sobolev; Adil Amirjanov

    2007-01-01

    The behavior of particulate composite materials, such as portland cement concrete, depends to a large extent on the properties of their main constituent—the aggregates. Among the most important parameters affecting the performance of concrete are the packing density and corresponding particle size distribution (PSD) of aggregates. Better packing of aggregates improves the main engineering properties of composite materials: strength, modulus

  15. Particle Accelerator Applications: Ion and Electron Irradiation in Materials Science, Biology and Medicine

    SciTech Connect

    Rodriguez-Fernandez, Luis [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Mexico D.F., 01000 (Mexico)

    2010-09-10

    Although the developments of particle accelerators are devoted to basic study of matter constituents, since the beginning these machines have been applied with different purposes in many areas also. Today particle accelerators are essential instruments for science and technology. This work presents an overview of the main application for direct particle irradiation with accelerator in material science, biology and medicine. They are used for material synthesis by ion implantation and charged particle irradiation; to make coatings and micromachining; to characterize broad kind of samples by ion beam analysis techniques; as mass spectrometers for atomic isotopes determination. In biomedicine the accelerators are applied for the study of effects by charged particles on cells. In medicine the radiotherapy by electron irradiation is widely used, while hadrontherapy is still under development. Also, they are necessary for short life radioisotopes production required in radiodiagnostic.

  16. Nucleation and growth of atmospheric particles: Contribution of ion-mediated nucleation and role of low volatile organics condensation

    Microsoft Academic Search

    F. Yu; G. Luo

    2010-01-01

    Formation and subsequent growth of secondary particles is an important source of atmospheric aerosol and contributes significantly to climate effective aerosols. It is now generally accepted that H2SO4 and ions are involved in the nucleation process while low volatile organic gases (LV-SOG) and H2SO4 are involved in the growth process, although the relative contribution of ion versus neutral nucleation and

  17. The influence of the upper-atmosphere neutral particle density on the occurrence of equatorial spread-F

    Microsoft Academic Search

    G. G. Bowman

    1993-01-01

    Over extended periods of time spread-F occurrence is considered in equatorial latitudes at stations located in the region between the geomagnetic equator and the equatorial anomaly crest region. Distinct differences are observed in the annual and sunspot-cycle distributions for spread-F occurrence before midnight and after midnight. The paper proposes that before midnight the low upper-atmosphere neutral-particle densities (NPDs) at elevated

  18. Determination of neonicotinoid insecticides and strobilurin fungicides in particle phase atmospheric samples by liquid chromatography-tandem mass spectrometry.

    PubMed

    Raina-Fulton, Renata

    2015-06-01

    A liquid chromatography-tandem mass spectrometry method has been developed for the determination of neonicotinoids and strobilurin fungicides in the particle phase fraction of atmosphere samples. Filter samples were extracted with pressurized solvent extraction, followed by a cleanup step with solid phase extraction. Method detection limits for the seven neonicotinoid insecticides and six strobilurin fungicides were in the range of 1.0-4.0 pg/m(3). Samples were collected from June to September 2013 at two locations (Osoyoos and Oliver) in the southern Okanagan Valley Agricultural Region of British Columbia, where these insecticides and fungicides are recommended for use on tree fruit crops (apples, pears, cherries, peaches, apricots) and vineyards. This work represents the first detection of acetamiprid, imidacloprid, clothianidin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin in particle phase atmospheric samples collected in the Okanagan Valley in Canada. The highest particle phase atmospheric concentrations were observed for imidacloprid, pyraclostrobin, and trifloxystrobin at 360.0, 655.6, and 1908.2 pg/m(3), respectively. PMID:25961332

  19. In vitro macrophage response to nanometer-size particles from materials used in hip implants

    NASA Astrophysics Data System (ADS)

    VanOs, Robilyn

    Wear particle-induced inflammation leading to periprosthetic osteolysis remains a major cause of hip implant failure. As polyethylene particles from conventional metal-on-polyethylene implants have been associated with these failures, an interest in lower wear metal-on-metal (MM) bearings has emerged. However, the biological effects of nanometer-size chromium oxide particles, predominant type of wear particles produced by MM implants, remain mostly unknown. Therefore, this study aimed to determine the cytotoxicity of nanometer-size Cr2O3 particles on macrophages in vitro, by analyzing their effects on cell mortality and cytokine release and comparing them with those of similarly-sized alumina (Al2O3) particles (known to be relatively bioinert). Results showed that at high concentrations, nanometer-size Cr2O3 particles can be cytotoxic to macrophages, inducing significant decreases in total cell numbers and increases in necrosis. Results also showed that, at high concentrations, the cytotoxicity of Cr 2O3 particles was overall higher than that of Al2O 3 particles, even though Cr2O3 and Al2O 3 are both stable forms of ceramic materials. However, it appeared to be lower than that of previously reported conventional polyethylene and CoCrMo particles. Therefore, chromium oxide particles may not be the main culprit in initiating the inflammatory reaction in MM periprosthetic tissues.

  20. Atmospheric pressure plasma pretreatment of sugarcane bagasse: the influence of biomass particle size in the ozonation process.

    PubMed

    Souza-Corrêa, J A; Oliveira, C; Nascimento, V M; Wolf, L D; Gómez, E O; Rocha, G J M; Amorim, J

    2014-02-01

    Atmospheric pressure O? plasma was used to produce ozone in order to treat sugarcane bagasse as a function of particle sizes. The fixed bagasse moisture content was 50%. The delignification efficiency had small improvement due to ozonation process as a function of particle size, varying from 75 up to 80%. Few amounts of hemicellulose were removed, but the ozonation has not been affected significantly with particle size variance as well (from 30 up to 35%). The cellulose presented some losses below 1.0 mm size (8-15%) which was an unexpected result. The conversion of cellulose content into free sugar has shown a significant increase as the particle size has diminished as well. The best condition of the bagasse particle size was for 0.08 mm. For this case, a great quantity of cellulose (78.8%) was converted into glucose. Optical absorption spectroscopy was applied to determine ozone concentrations in real time where the samples with typical bagasse particle sizes equal or below to 0.5 mm had shown a better absorption of ozone in comparison with greater particle size samples. PMID:24242163

  1. On Formation Of HXR, Hydrogen, White Light Emission and Sunquakes in Hydrodynamic Flaring Atmospheres Heated by Particle Beams

    NASA Astrophysics Data System (ADS)

    Dobranskis, R.; Zharkova, V. V.; Zharkov, S.; Druett, M.

    2014-12-01

    We report analysis of kinetic simulations for precipitation of various particle beams (electrons, protons, mixed beam) and hydrodynamic simulations of flaring atmosphere heating by these beams using the approach described by Zharkova and Zharkov (2007). The results show temperature, density and macro-velocity variations as functions of both column and linear depths that for some beam parameters reveals a strong suppression of the upper atmosphere in a form of shocks towards the photosphere and beneath into the solar interior at some distances of 500-3000 km. The shocks deposited at different depths below the photosphere are found to produce varying seismic responses as per model by Zharkov (2013) while the atmospheres above the photosphere reveal various degrees of evaporation of the pressed ambient plasma into the corona depending on beam parameters. After a beam switch off the flaring atmospheres are shown to relax within short timescales to their original status. For physical models corresponding to hydrodynamic responses above we also simulate hydrogen emission produced by these atmospheres using full non-LTE approach and considering collisional excitation and ionisation by electron beams. We compare temporal and spatial distributions of HXR and optical emission in some flares with those produced by the complex simulations above, in attempt to resolve the puzzle of co-spatial formation of HXR and WL emission reported by Martinez-Oliveros et al. (2012).

  2. ALADINA - an unmanned research aircraft for observing vertical and horizontal distributions of ultrafine particles within the atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Altstädter, B.; Platis, A.; Wehner, B.; Scholtz, A.; Wildmann, N.; Hermann, M.; Käthner, R.; Baars, H.; Bange, J.; Lampert, A.

    2015-04-01

    This paper presents the unmanned research aircraft Carolo P360 "ALADINA" (Application of Light-weight Aircraft for Detecting IN situ Aerosol) for investigating the horizontal and vertical distribution of ultrafine particles in the atmospheric boundary layer (ABL). It has a wingspan of 3.6 m, a maximum take-off weight of 25 kg and is equipped with aerosol instrumentation and meteorological sensors. A first application of the system, together with the unmanned research aircraft MASC (Multi-Purpose Airborne Carrier) of the Eberhard Karls University of Tübingen (EKUT), is described. As small payload for ALADINA, two condensation particle counters (CPC) and one optical particle counter (OPC) were miniaturised by re-arranging the vital parts and composing them in a space-saving way in the front compartment of the airframe. The CPCs are improved concerning the lower detection threshold and the response time to less than 1.3 s. Each system was characterised in the laboratory and calibrated with test aerosols. The CPCs are operated in this study with two different lower detection threshold diameters of 11 and 18 nm. The amount of ultrafine particles, which is an indicator for new particle formation, is derived from the difference in number concentrations of the two CPCs (?N). Turbulence and thermodynamic structure of the boundary layer are described by measurements of fast meteorological sensors that are mounted at the aircraft nose. A first demonstration of ALADINA and a feasibility study were conducted in Melpitz near Leipzig, Germany, at the Global Atmosphere Watch (GAW) station of the Leibniz Institute for Tropospheric Research (TROPOS) on 2 days in October 2013. There, various ground-based instruments are installed for long-term atmospheric monitoring. The ground-based infrastructure provides valuable additional background information to embed the flights in the continuous atmospheric context and is used for validation of the airborne results. The development of the boundary layer, derived from backscatter signals of a portable Raman lidar POLLYXT, allows a quick overview of the current vertical structure of atmospheric particles. Ground-based aerosol number concentrations are consistent with the results from flights in heights of a few metres. In addition, a direct comparison of ALADINA aerosol data and ground-based aerosol data, sampling the air at the same location for more than 1 h, shows comparable values within the range of ± 20 %. MASC was operated simultaneously with complementary flight patterns. It is equipped with the same meteorological instruments that offer the possibility to determine turbulent fluxes. Therefore, additional information about meteorological conditions was collected in the lowest part of the atmosphere. Vertical profiles up to 1000 m in altitude indicate a high variability with distinct layers of aerosol, especially for the small particles of a few nanometres in diameter on 1 particular day. The stratification was almost neutral and two significant aerosol layers were detected with total aerosol number concentrations up to 17 000 ± 3400 cm-3 between 180 and 220 m altitude and 14 000 ± 2800 cm-3 between 550 and 650 m. Apart from those layers, the aerosol distribution was well mixed and reached the total number concentration of less than 8000 ± 1600 cm-3. During another day, the distribution of the small particles in the lowermost ABL was related to the stratification, with continuously decreasing number concentrations from 16 000 ± 3200 cm-3 to a minimum of 4000 ± 800 cm-3 at the top of the inversion at 320 m. Above this, the total number concentration was rather constant. In the region of 500 to 600 m altitude, a significant difference of both CPCs was observed. This event occurred during the boundary layer development in the morning and represents a particle burst within the ABL.

  3. Atmospheric Environment 40 (2006) 68636878 Acid-catalyzed reactions of hexanal on sulfuric acid particles

    E-print Network

    Elrod, Matthew J.

    2006-01-01

    Atmospheric Environment 40 (2006) 6863­6878 Acid-catalyzed reactions of hexanal on sulfuric acid are incorporated into atmospheric aerosols are not well understood. Acid-catalyzed reactions of compounds into acidic aerosols. In the present study, we use the aerodyne aerosol mass spectrometer (AMS) to probe

  4. Atmospheric Distribution of Gas and Particle-Phase Quinones in Southern California

    Microsoft Academic Search

    Arantzazu Eiguren-Fernandez; Antonio H. Miguel; Emma Di Stefano; Debra A. Schmitz; Arthur K. Cho; Suresh Thurairatnam; Ed L. Avol; John R. Froines

    2008-01-01

    Quinones are reactive organic compounds known to initiate reactions associated with a host of toxicological events. Their presence in different atmospheres has been demonstrated although their sources remain uncertain. As a result of their reactivity and instability during chemical analysis, only a limited number of studies have reported on atmospheric concentrations of quinones in ambient air. Furthermore, besides the limited

  5. Automated technologies needed to prevent radioactive materials from reentering the atmosphere

    NASA Astrophysics Data System (ADS)

    Buden, David; Angelo, Joseph A., Jr.

    Project SIREN (Search, Intercept, Retrieve, Expulsion Nuclear) was created to identify and evaluate the technologies and operational strategies needed to rendezvous with and capture aerospace radioactive materials (e.g., a distressed or spent space reactor core) before such materials can reenter the terrestrial atmosphere and then to safely move these captured materials to an acceptable space destination for proper disposal. A major component of the current project SIREN effort is the development of an interactive technology model (including a computerized data base) that explores, in building-block fashion, the interaction of the technologies and procedures needed to successfully accomplish a SIREN mission. The SIREN model will include appropriate national and international technology elements--both contemporary and projected into the next century. To obtain maximum flexibility and use, the SIREN technology data base is being programmed for use on 286-class PC's. The major technical elements for a successful SIREN mission include: ground and space-based tracking, launch vehicles of needed payload capacity, telerobotic systems, sensors, capture technologies, and space transport and disposal. However, Project SIREN also will impose specialized requirements including the use of dextrous aerospace systems capable of properly functioning in intense radiation and thermal environments.

  6. Lanthanum hexaaluminate—a new material for atmospheric plasma spraying of advanced thermal barrier coatings

    NASA Astrophysics Data System (ADS)

    Friedrich, C.; Gadow, R.; Schirmer, T.

    2001-12-01

    One of the main application fields of the thermal spraying process is thermal barrier coatings (TBCs). Today, partially stabilized zirconia (YSZ or MSZ) is mainly used as a TBC material. At temperatures above 1000 °C, zirconia layers age distinctively, including phenomena shrinkage and microcrack formation. Therefore, there is a considerable interest in TBCs for higher temperature applications. In this paper, lanthanum hexaaluminate, a newly developed TBC material with long-term stability up to 1400 °C, is presented. It ages significantly more slowly at these high temperatures than commercial zirconia-based TBCs. Its composition favors the formation of platelets, which prevent a densification of the coating by postsintering. It consists of La2O3, Al2O3, and MgO. Its crystal structure corresponds to a magnetoplumbite phase. Lanthanum hexaaluminate powders were produced using two different fabrication routes, one based on salts and the other one based on oxides. To optimize the granulate, various raw materials and additives were tested. The slurry was spray dried in a laboratory spray drier and calcined at 1650 °C. Using these two powders, coatings were produced by atmospheric plasma spraying (APS). The residual stresses of the coatings were measured by the hole drilling method, and the deposition process was optimized with respect to the residual stresses in the TBC. The coatings were extensively analyzed regarding phase composition, thermal expansion, and long-term stability, as well as microstructural properties.

  7. Particle induced damage on heads and discs due to fine particles of different materials

    Microsoft Academic Search

    Lihong Zhang; Ramesh Koka; Yewwah Yuen; Edwin Lam

    1999-01-01

    Fine particles of aluminum, stainless steel, silicon, slider ceramic (Al2O3-TiC) and sputtered alumina were introduced at the head\\/disc interface of hard disc drives. Experiments were conducted with discs made from aluminum and glass substrates. Glass substrates were much harder than aluminum substrates. It was found that the type of damage introduced on the disc and slider was to some extent

  8. Influence of the Spray Angle on the Characteristics of Atmospheric Plasma Sprayed Hard Material Based Coatings

    NASA Astrophysics Data System (ADS)

    Tillmann, Wolfgang; Vogli, Evelina; Krebs, Benjamin

    2008-12-01

    This paper presents an investigation of the influence of the spray angle on thermally sprayed coatings. Spray beads were manufactured with different spray angles between 90 and 20° by means of atmospheric plasma spraying (APS) on heat-treated mild steel (1.0503). WC-12Co and Cr3C2-10(Ni20Cr) powders were employed as feedstock materials. Every spray bead was characterized by a Gaussian fit. This opens the opportunity to analyze the influence of the spray angle on coating properties. Furthermore, metallographic studies of the surface roughness, porosity, hardness, and morphology were carried out and the deposition efficiency as well as the tensile strength was measured. The thermally sprayed coatings show a clear dependence on the spray angle. A decrease in spray angle changes the thickness, width, and form of the spray beads. The coatings become rougher and their quality decreases.

  9. Anthropogenic Influence on Secondary Aerosol Formation and Total Water-Soluble Carbon on Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Gioda, Adriana; Mateus, Vinicius; Monteiro, Isabela; Taira, Fabio; Esteves, Veronica; Saint'Pierre, Tatiana

    2013-04-01

    On a global scale, the atmosphere is an important source of nutrients, as well as pollutants, because of its interfaces with soil and water. Important compounds in the gaseous phase are in both organic and inorganic forms, such as organic acids, nitrogen, sulfur and chloride. In spite of the species in gas form, a huge number of process, anthropogenic and natural, are able to form aerosols, which may be transported over long distances. Sulfates e nitrates are responsible for rain acidity; they may also increase the solubility of organic compounds and metals making them more bioavailable, and also can act as cloud condensation nuclei (CCN). Aerosol samples (PM2.5) were collected in a rural and industrial area in Rio de Janeiro, Brazil, in order to quantify chemical species and evaluate anthropogenic influences in secondary aerosol formation and organic compounds. Samples were collected during 24 h every six days using a high-volume sampler from August 2010 to July 2011. The aerosol mass was determined by Gravimetry. The water-soluble ionic composition (WSIC) was obtained by Ion Chromatography in order to determine the major anions (NO3-, SO4= and Cl-); total water-soluble carbon (TWSC) was determined by a TOC analyzer. The average aerosol (PM2.5) concentrations ranged from 1 to 43 ug/m3 in the industrial site and from 4 to 35 ug/m3 in the rural area. Regarding anions, the highest concentrations were measured for SO42- (10.6 ?g/m3-12.6 ?g/m3); where the lowest value was found in the rural site and the highest in the industrial. The concentrations for NO3- and Cl- ranged from 4.2 ?g/m3 to 9.3 ?g/m3 and 3.1 ?g/m3 to 6.4 ?g /m3, respectively. Sulfate was the major species and, like nitrate, it is related to photooxidation in the atmosphere. Interestingly sulfate concentrations were higher during the dry period and could be related to photochemistry activity. The correlations between nitrate and non-sea-salt sulfate were weak, suggesting different sources for these species. The secondary aerosol represented an important fraction of total compounds in PM2.5 ranged from 16 to 18% for (NH4)2SO4 and 6 to 8% for NH4NO3. The values for TWSC ranged from 0.28 to 6.35 ?g/m3 in the industrial area and 0.12 to 7.49 ?g/m3 for rural area. The similarity between the areas regarding secondary aerosols formation and water-soluble carbon compounds is probably due to the particle size.

  10. Fluorescence spectra and elastic scattering characteristics of atmospheric aerosol in Las Cruces, New Mexico, USA: Variability of concentrations and possible constituents and sources of particles in various spectral clusters

    NASA Astrophysics Data System (ADS)

    Pinnick, R. G.; Fernandez, E.; Rosen, J. M.; Hill, S. C.; Wang, Y.; Pan, Y. L.

    2013-02-01

    The UV-excited laser-induced-fluorescence (UV-LIF) spectra of single atmospheric particles and the three-band integrating-nephelometer elastic scattering of atmospheric aerosol were measured during four approximately 24-h periods on May 2007 in Las Cruces, New Mexico, USA. Aerosol scattering measurements in the nephelometer red channel (50-nm band centered at 700-nm) ranged from around 3-10 times the molecular (Rayleigh) scattering background. On average 22.8% of particles with size greater than about 1 ?m diameter have fluorescence above a preset fluorescence threshold. A hierarchical cluster analysis indicates that most of the single-particle UV-LIF spectra fall into about 10 categories (spectral clusters) as found previously at other geographic sites (Pinnick et al., 2004; Pan et al., 2007). The clusters include spectra characteristic of various humic/fulvic acids, humic-like-substances (HULIS), chemically aged terpenes, fungal spores, polycyclic aromatic hydrocarbons, bacteria, cellulose/pollens, and mixtures of various organic carbon compounds. By far the most populated cluster category is similar to those of chemically aged terpenes/humic-materials; on average this population comprises about 62% of fluorescent particles. Clusters with spectra similar to that of some HULIS aerosol contain on average 10.0% of particles; those characteristic of some fungal spores (or perhaps mixtures of aromatic organic compounds) 8.4% of particles; bacteria-like spectra 1.6% of particles; and cellulose/pollen-like spectra 0.8% of particles. Measurements of fluorescent particles over relatively short (24 min) periods reveal that the concentrations of particles in the most populated clusters are highly correlated, suggesting that the particles populating them derive from the same region; these particles might be composed of crustal material coated with secondary organic carbon. On the other hand, concentrations of particles having cellulose-like spectra are generally uncorrelated with those in any other cluster. No clear distinction in fluorescent aerosol characteristics can be seen for different air mass trajectories arriving at the sampling site, suggesting that fluorescent aerosol particles are primarily of local origin. Integrations of the single-particle UV-LIF spectra over approximate 24 h time intervals reveal two broad peaks around 350 nm and 450 nm (for 263 nm excitation); the 450 nm peak is somewhat similar to that measured previously for water soluble organic carbon derived from aerosol collections. The 350 nm peak apparently has not been seen before in measurements of aerosol collections and may derive from non-soluble primary biological aerosol particles such as fungal spores. Further measurements are needed to investigate in more detail the generality of these results.

  11. Characterization of Atmospheric Pressure Plasma Torch and the Surface Interaction for Material Removal

    NASA Astrophysics Data System (ADS)

    McWilliams, Anthony Joseph

    An atmospheric pressure plasma torch has been developed and characterized for removal of organic based coatings. The focus of the Strategic Environmental Research & Development Program (SERDP) project WP-1762, that funded the bulk of this dissertation work, is removal of paint from US Navy vessels. The goal is to develop a novel technology for coating removal that is capable of reducing the amount of environmental waste produced during the commonly used grit blasting process. The atmospheric pressure air plasma torch was identified as having the capacity to remove the paint systems while using only compressed air and electricity as a media-less removal system with drastically reduced waste generation. Any improvements to the existing technology need to be based on scientific knowledge and thus the plasma removal mechanisms or material warranted investigation. The removal of material does not show a strong relation to the plasma parameters of power, frequency, and gas flow, nor is there a strong relation to the presences of inorganic fillers impeding or altering the removal rates. The underlying removal mechanisms also do not show a strong correlation to the rotational temperature of the plasma but do show a strong correlation to the optical emission intensity. Primarily, the emission from atomic oxygen and molecular nitrogen were identified significant contributors and were investigated further. The plasma feed gas was then varied from the nitrogen and oxygen ratio present in ambient air to pure nitrogen to identify the effect of oxygen on the removal mechanism. From these experiments it was concluded that the oxygen present in air does contribute to the overall removal mechanism; however, it is not the sole contributing factor with the other major factor being nitrogen.

  12. ALADINA - an unmanned research aircraft for observing vertical and horizontal distributions of ultrafine particles within the atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Altstädter, B.; Platis, A.; Wehner, B.; Scholtz, A.; Lampert, A.; Wildmann, N.; Hermann, M.; Käthner, R.; Bange, J.; Baars, H.

    2014-12-01

    This paper presents the unmanned research aircraft Carolo P360 "ALADINA" (Application of Light-weight Aircraft for Detecting IN-situ Aerosol) for investigating the horizontal and vertical distribution of ultrafine particles in the atmospheric boundary layer (ABL). It has a wingspan of 3.6 m, a maximum take-off weight of 25 kg and is equipped with aerosol instrumentation and meteorological sensors. A first application of the system, together with the unmanned research aircraft MASC (Multi-Purpose Airborne Carrier) of the Eberhard-Karls University of Tübingen (EKUT), is described. As small payload for ALADINA, two condensation particle counters (CPC) and one optical particle counter (OPC) were miniaturized by re-arranging the vital parts and composing them in a space saving way in the front compartment of the airframe. The CPCs are improved concerning the lower detection threshold and the response time. Each system was characterized in the laboratory and calibrated with test aerosols. The CPCs are operated with two different lower detection threshold diameters of 6 and 18 nm. The amount of ultrafine particles, which is an indicator for new particle formation, is derived from the difference in number concentrations of the two CPCs. Turbulence and thermodynamic structure of the boundary layer are described by measurements of fast meteorological sensors that are mounted at the aircraft nose. A first demonstration of ALADINA and a feasibility study were conducted in Melpitz near Leipzig, Germany, at the Global Atmosphere Watch (GAW) station of the Leibniz Institute for Tropospheric Research (TROPOS) on two days in October 2013. There, various ground-based instruments are installed for long-term atmospheric monitoring. The ground-based infrastructure provides valuable additional background information to embed the flights in the continuous atmospheric context and is used for validation of the airborne results. The development of the boundary layer, derived from backscatter signals of a portable Raman lidar POLLYXT, allows a quick overview of the current vertical structure of atmospheric particles. Ground-based aerosol number concentrations are consistent with the results from flights in heights of a few meters. In addition, a direct comparison of ALADINA aerosol data and ground-based aerosol data, sampling the air at the same location, shows comparable values. MASC was operated simultaneously with complementary flight patterns. It is equipped with the same meteorological instruments that offer the possibility to determine turbulent fluxes. Therefore additional information about meteorological conditions was collected in the lowest part of the atmosphere. Vertical profiles up to 1000 m altitude indicate a high variability with distinct layers of aerosol especially for the small particles of a few nanometers in diameter. Particle bursts were observed on one day during the boundary layer development in the morning.

  13. Classification of Multiple Types of Organic Carbon Composition in Atmospheric Particles by Scanning Transmission X-Ray Microscopy Analysis

    SciTech Connect

    Kilcoyne, Arthur L; Takahama, S.; Gilardoni, S.; Russell, L.M.; Kilcoyne, A.L.D.

    2007-05-16

    A scanning transmission X-ray microscope at the Lawrence Berkeley National Laboratory is used to measure organic functional group abundance and morphology of atmospheric aerosols. We present a summary of spectra, sizes, and shapes observed in 595 particles that were collected and analyzed between 2000 and 2006. These particles ranged between 0.1 and 12 mm and represent aerosols found in a large range of geographical areas, altitudes, and times. They include samples from seven different field campaigns: PELTI, ACE-ASIA, DYCOMS II, Princeton, MILAGRO (urban), MILAGRO (C-130), and INTEX-B. At least 14 different classes of organic particles show different types of spectroscopic signatures. Different particle types are found within the same region while the same particle types are also found in different geographical domains. Particles chemically resembling black carbon, humic-like aerosols, pine ultisol, and secondary or processed aerosol have been identified from functional group abundance and comparison of spectra with those published in the literature.

  14. Comparison of Contributions of Wind-blown and Anthropogenic Fugitive Dust Particles to Atmospheric Particulate Matter

    NASA Astrophysics Data System (ADS)

    Park, S.; Gong, S.

    2010-12-01

    A new wind-blown-dust emissions module was recently implemented into AURAMS, a Canadian regional air quality model (Park et al., 2009; Park et al., 2007), to investigate the relative impact of wind-blown dust vs. anthropogenic fugitive dust on air quality in North America. In order to apply the wind-blown dust emissions module to the entire North American continent, a soil-grain-size-distribution map was developed using the outputs of four monthly runs of AURAMS for 2002 and available PM2.5 dust-content observations. The simulation results using the new soil-grain-size-distribution map showed that inclusion of wind-blown dust emissions is essential to predict the impact of dust aerosols on air quality in North America, especially in the western U.S.. The wind-blown dust emissions varied widely by season, whereas the anthropogenic fugitive dust emissions did not change significantly. In the spring (April), the continental monthly average emissions rate of wind-blown dust was much higher than that of anthropogenic fugitive dust. The total amount of wind-blown dust emissions in North America predicted by the model for 2002 was comparable to that of anthropogenic fugitive dust emissions. Even with the inclusion of wind-blown dust emissions, however, the model still had difficulty simulating dust concentrations. Further improvements are needed, in terms of both limitations of the wind-blown-dust emission module and uncertainties in the anthropogenic fugitive dust emissions inventories, for improved dust modelling. References Park, S.H., S.L. Gong, W. Gong, P.A. Makar, M.D. Moran, C.A. Stroud, and J. Zhang, Sensitivity of surface characteristics on the simulation of wind-blown dust source in North America, Atmospheric Environment, 43 (19), 3122-3129, 2009. Park, S.H., S.L. Gong, T.L. Zhao, R.J. Vet, V.S. Bouchet, W. Gong, P.A. Makar, M.D. Moran, C. Stroud, and J. Zhang, Simulation of entrainment and transport of dust particles within North America in April 2001 ("Red Dust Episode"), Journal of Geophysical Research, 112, D20209, doi:10.1029/2007JD008443, 2007.

  15. The Stopping Power of Asteroidal Materials as High-Energy Charged Particle Shielding

    NASA Astrophysics Data System (ADS)

    Pohl, Leos; Johnson, Daniel; Britt, Daniel

    2014-11-01

    Extended human missions in deep space face a challenging radiation environment from high-energy galactic cosmic rays and solar energetic particles generated by solar flares and related coronal mass ejections. Shielding to attenuate these high-energy particles will require significant mass and volume, and would be extremely expensive launch from the surface of the earth. One possible solution could be the use of asteroidal resources as shielding for these high-energy particles. The effectiveness of shielding material for moderately relativistic charged particles is a function of the mean rate of energy loss, primarily to ionization and atomic excitation and is termed stopping power. In general, low atomic number elements are more effective per unit volume. We have calculated the stopping power for the average compositions of all major meteorite groups and will compare these data with typical spacecraft materials.

  16. Organic particulate material levels in the atmosphere: conditions favoring sensitivity to varying relative humidity and temperature.

    PubMed

    Pankow, James F

    2010-04-13

    This study examines the sensitivity in predicted levels of atmospheric organic particulate matter (M(o), microg m(-3)) as those levels may potentially be affected by changes in relative humidity and temperature. In a given system, for each partitioning compound, f(g) and f(p) represent the gaseous and particulate fractions (f(g) + f(p) = 1). Sensitivity in the M(o) levels becomes dampened as the compounds contributing significantly to M(o) are increasingly found in the particle phase (f(p) --> 1). Thus, although local maxima in sensitivity can be encountered as M(o) levels increase, because as M(o) increases each f(p) --> 1, then increasing M(o) levels generally tend to reduce sensitivity in M(o) levels to changes in relative humidity and temperature. Experiments designed to elucidate the potential magnitudes of the effects of relative humidity and temperature on M(o) levels must be carried out at M(o) levels that are relevant for the ambient atmosphere: The f(p) values for the important partitioning compounds must not be elevated above ambient-relevant values. Systems in which M(o) levels are low (e.g., 1-2 microg m(-3)) and/or composed of unaged secondary organic aerosol are the ones most likely to show sensitivity to changing relative humidity and temperature. Results from two published chamber studies are examined in the above regard: [Warren B, et al. (2009) Atmos Environ 43:1789-1795] and [Prisle NL, et al. (2010) Geophys Res Lett 37:L01802]. PMID:20368456

  17. Charged-Particle Emission upon Ruby Laser Irradiation of Transparent Dielectric Materials

    Microsoft Academic Search

    D. L. Rousseau; G. E. Leroi; W. E. Falconer

    1968-01-01

    Positive and negative charged particle currents induced in vacuo by high-power laser irradiation of transparent dielectric materials below the threshold for physical damage have been investigated. Soft glass, Pyrex, fused quartz, Supracil quartz, CaF2, LiF, and sapphire all show similar behavior. Currents as large as 1010 charged particles per pulse are obtained using ruby laser radiation with normal mode power

  18. Particle size analysis of prepared solutions and fingerprint deposits of high explosive materials

    SciTech Connect

    Carmack, W.J.; Hembree, P.B.

    1998-03-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) managed and operated by Lockheed Martin Idaho Technologies Company (LMITCO) was tasked via the Federal Aviation Administration (FAA) and US Department of Energy (DOE) to conduct various studies involving the detection and measurement of explosive materials and their associated residues. This report details the results of an investigation to determine the particle size characteristics of the explosive materials used in the design, development, and testing of trace explosives detection systems. These materials, in the form of water suspensions of plastic explosives, are used to provide a quantitative means of monitoring the performance characteristics of the detection systems. The purpose of this investigation is to provide data that allows a comparison between the particles deposited using the suspension standards and the particles deposited from fingerprints. This information may support the development of quality control aids, measurement methods, or performance criteria specifications for the use of trace explosives detection systems. For this report, particle size analyses were completed on explosives standard suspensions/solutions for composition C-4, Semtex-H, and Detasheet and fingerprints for C-4, Detasheet, and pentolite. Because of the difficulty in collecting microscopic images of the particles in the suspensions from test protocol surfaces, this paper discusses the characteristics of the particles as they are found on metal, glass, and paper. The results of the particle characterization analyses indicate that the water suspensions contain particulate composed of binder materials and dissolved portions of the explosive compounds. Upon drying of the water suspensions, significant particle nucleation and growth is observed. The nucleated particulate is comparable to the particulate deposited by fingerprints.

  19. Size distributions of atmospheric particles: Scale dependence, scattering properties of nonspherical particles and retrieval by inversion of spectral optical depth

    Microsoft Academic Search

    Yangang Liu

    1998-01-01

    As an investigation into size distributions of cloud particles from both the theoretical and instrumental points of view, this dissertation is mainly concerned with four topics. First, a systems theory is developed to study size distributions based on Shannon's maximum entropy principle and an energy barrier argument. This new theory reveals the scale-dependence of size distributions and provides an explanation

  20. Composition and properties of atmospheric particles in the eastern Atlantic and impacts on gas phase uptake rates

    NASA Astrophysics Data System (ADS)

    Allan, J. D.; Topping, D. O.; Good, N.; Irwin, M.; Flynn, M.; Williams, P. I.; Coe, H.; Baker, A. R.; Martino, M.; Niedermeier, N.; Wiedensohler, A.; Lehmann, S.; Müller, K.; Herrmann, H.; McFiggans, G.

    2009-12-01

    Marine aerosol composition continues to represent a large source of uncertainty in the study of climate and atmospheric chemistry. In addition to their physical size and chemical composition, hygroscopicity plays a significant role, increasing the particles' surface areas and scattering potential. Simultaneous aerosol measurements were performed on board the RRS Discovery and at the Cape Verde atmospheric observatory during the Aerosol Composition and Modelling in the Marine Environment (ACMME) and Reactive Halogens in the Marine Boundary Layer (RHAMBLE) experiments. These included online measurements of number and dry size and bulk collection for offline analysis of aqueous ions. In addition, the measurements on board the Discovery included online measurements of composition using an Aerodyne Aerosol Mass Spectrometer, optical absorption using a Multi Angle Absorption Photometer, ambient humidity size distribution measurements using a humidified differential mobility particle sizer (DMPS) and optical particle counter (OPC) and hygroscopicity measurements with a hygroscopicity tandem differential mobility analyser (HTDMA). Good agreement between platforms in terms of the sea salt (ss) and non sea salt (nss) modes was found during the period when the Discovery was in close proximity to Cape Verde and showed a composition consistent with remote marine air. As the Discovery approached the African coast, the aerosol showed signs of continental influence such as an increase in particle number, optical absorption, enhancement of the nss mode and dust particles. The Cape Verde site was free of this influence during this period. Chloride and bromide showed concentrations with significant deviations from seawater relative to sodium, indicating that atmospheric halogen processing (and/or acid displacement for chloride) had taken place. The time dependent ambient size distribution was synthesised using humidified DMPS and OPC data, corrected to ambient humidity using HTDMA data. Heterogeneous uptake rates of hypoiodous acid (HOI) were also predicted and the nss accumulation mode was found to be the most significant part of the size distribution, which could act as an inert sink for this species. The predicted uptake rates were enhanced by around a factor of 2 during the African influence period due to the addition of both coarse and fine particles. The hygroscopicity of the nss fraction was modelled using the Aerosol Diameter Dependent Equilibrium Model (ADDEM) using the measured composition and results compared with the HTDMA data. This was the first time such a reconciliation study with this model has been performed with marine data and good agreement was reached within the resolution of the instruments. The effect of hygroscopic growth on HOI uptake was also modelled and ambient uptake rates were found to be approximately doubled compared to equivalent dry particles.

  1. Composition and properties of atmospheric particles in the eastern Atlantic and impacts on gas phase uptake rates

    NASA Astrophysics Data System (ADS)

    Allan, J. D.; Topping, D. O.; Good, N.; Irwin, M.; Flynn, M.; Williams, P. I.; Coe, H.; Baker, A. R.; Martino, M.; Niedermeier, N.; Wiedensohler, A.; Lehmann, S.; Müller, K.; Herrmann, H.; McFiggans, G.

    2009-09-01

    Marine aerosol composition continues to represent a large source of uncertainty in the study of climate and atmospheric chemistry. In addition to their physical size and chemical composition, hygroscopicity plays a significant role, increasing the particles' surface areas and scattering potential. Simultaneous aerosol measurements were performed on board the RRS Discovery and at the Cape Verde atmospheric observatory during the Aerosol Composition and Modelling in the Marine Environment (ACMME) and Reactive Halogens in the Marine Boundary Layer (RHAMBLE) experiments. These included online measurements of number and dry size and bulk collection for offline analysis of aqueous ions. In addition, the measurements on board the Discovery included online measurements of composition using an Aerodyne Aerosol Mass Spectrometer, optical absorption using a Multi Angle Absorption Photometer, ambient humidity size distribution measurements using a humidified differential mobility particle sizer (DMPS) and optical particle counter (OPC) and hygroscopicity measurements with a hygroscopicity tandem differential mobility analyser (HTDMA). Good agreement between platforms in terms of the sea salt (ss) and non sea salt (nss) modes was found during the period when the Discovery was in close proximity to Cape Verde and showed a composition consistent with remote marine air. As the Discovery approached the African coast, the aerosol showed signs of continental influence such as an increase in particle number, optical absorption, enhancement of the nss mode and dust particles. The Cape Verde site was free of this influence during this period. Chloride and bromide showed concentrations with significant deviations from seawater relative to sodium, indicating that atmospheric halogen processing (and/or acid displacement for chloride) had taken place. The time dependent ambient size distribution was synthesised using humidified DMPS and OPC data, corrected to ambient humidity using HTDMA data. Heterogeneous uptake rates of HOI were also predicted and the nss accumulation mode was found to be the most significant part of the size distribution, which could act as an inert sink for this species. The predicted uptake rates were enhanced by around a factor of 2 during the African influence period due to the addition of both coarse and fine particles. The hygroscopicity of the nss fraction was modelled using the Aerosol Diameter Dependent Equilibrium Model (ADDEM) using the measured composition and results compared with the HTDMA data. This was the first time such a reconciliation study with this model has been performed with marine data and good agreement was reached within the resolution of the instruments. The effect of hygroscopic growth on HOI uptake was also modelled and ambient uptake rates were found to be approximately doubled compared to equivalent dry particles.

  2. Change in surface of polymer materials upon irradiation of accelerated micro-particles

    NASA Astrophysics Data System (ADS)

    Kudo, Hisaaki; Tadokoro, Masashi; Narita, Shintaro; Matsuoka, Leo; Muroya, Yusa; Katsumura, Yosuke

    2005-07-01

    As a new method of use of a particle accelerator (ionizing radiation generator), we irradiated accelerated micro-particles of silver (Ag) onto polymer materials such as polyimides, glass, ceramics and semi-conductors. The particles can be generated at a Van de Graaff electrostatic accelerator operating at 1-3 MV. The velocity was around 1-10 km/s, size of diameter was about 1-10 ?m and charge was about 1-2 ?C. We investigated the change in surface of materials upon irradiation, by using laser microscope, atomic force microscope and scanning electron microscope. Crater-shaped irradiation spots having limb structure were found, and their diameter and depth were evaluated, ranging in a few micrometers. The planar distribution of the projectile around the irradiation spot was examined with energy dispersive X-ray spectroscopy. Correlation between size of the irradiation spots and kinetic energy of the accelerated micro-particles was investigated, and compared with an empirical formula and molecular dynamics study. Numerical simulation dealing with dynamic behaviour of elastic structure was carried out based on SPH (Smoothed Particle Hydrodynamics) method, a kind of (virtual) particle method. The simulation also found that a crater-shaped spot having limb structure is formed upon collision of the accelerated projectile with the target-materials. The results of simulation were compared with the experimental observations. These experiment and simulation are important for the evaluation of damages and resistance of polymer materials used in the space, such as the thermal control material, and cover glass of solar cells etc., towards space debris and dusts. It would be complement the on-ground radiation resistant tests on the materials conducted by using electron and ion beam accelerators.

  3. Status of materials handbooks for particle accelerator and nuclear reactor applications

    SciTech Connect

    Maloy, Stuart [Los Alamos National Laboratory (LANL); Rogers, Berylene [Los Alamos National Laboratory (LANL); Ren, Weiju [ORNL; Philip, Rittenhouse [Consultant

    2008-01-01

    In support of research and development for accelerator applications, a materials handbook was developed in August of 1998 funded by the Accelerator Production of Tritium Project. This handbook, presently called Advanced Fuel Cycle Initiative (AFCI) Materials Handbook, Materials Data for Particle Accelerator Applications, has just issued Revision 5 and contains detailed information showing the effects of irradiation on many properties for a wide variety of materials. Development of a web-accessible materials database for Generation IV Reactor Programs has been ongoing for about three years. This handbook provides a single authoritative source for qualified materials data applicable to all Generation IV reactor concepts. A beta version of this Gen IV Materials Handbook has been completed and is presently under evaluation.

  4. UV-VIS backscattering measurements on atmospheric particles mixture using polarization lidar coupled with numerical simulations and laboratory experiments

    NASA Astrophysics Data System (ADS)

    Miffre, Alain; Francis, Mirvatte; Anselmo, Christophe; Rairoux, Patrick

    2015-04-01

    As underlined by the latest IPCC report [1], tropospheric aerosols are nowadays recognized as one of the main uncertainties affecting the Earth's climate and human health. This issue is not straightforward due to the complexity of these nanoparticles, which present a wide range of sizes, shapes and chemical composition, which vary as a function of altitude, especially in the troposphere, where strong temperature variations are encountered under different water vapour content (from 10 to 100 % relative humidity). During this oral presentation, I will first present the scientific context of this research. Then, the UV-VIS polarimeter instrument and the subsequent calibration procedure [2] will be presented, allowing quantitative evaluation of particles backscattering coefficients in the atmosphere. In this way, up to three-component particles external mixtures can be partitioned into their spherical and non-spherical components, by coupling UV-VIS depolarization lidar measurements with numerical simulations of backscattering properties specific to non-spherical particles, such as desert dust or sea-salt particles [3], by applying the T-matrix numerical code [4]. This combined methodology is new, as opposed to the traditional approach using the lidar and T-matrix methodologies separately. In complement, recent laboratory findings [5] and field applications [6] will be presented, enhancing the sensitivity of the UV-VIS polarimeter. References [1] IPCC report, Intergovernmental Panel on Climate Change, IPCC, (2013). [2] G. David, A. Miffre, B. Thomas, and P. Rairoux: "Sensitive and accurate dual-wavelength UV-VIS polarization detector for optical remote sensing of tropospheric aerosols," Appl. Phys. B 108, 197-216 (2012). [3] G. David, B. Thomas, T. Nousiainen, A. Miffre and P. Rairoux: "Retrieving simulated volcanic, desert dust, and sea-salt particle properties from two / three-component particle mixtures using UV-VIS polarization Lidar and T-matrix," Atmos. Chem Phys. 13, 6757-6776 (2013). [4] M.I. Mishchenko, L.D. Travis and A.A. Lacis: "Scattering, absorption and emission of Light by small particles," 3rd edition, Cambridge University Press UK, (2002). [5] G. David, B. Thomas, E. Coillet, A. Miffre, and P. Rairoux, Polarization-resolved exact light backscattering by an ensemble of particles in air, Opt. Exp., 21, No. 16, 18624-18639, (2013). [6] G. David, B. Thomas, Y. Dupart, B. D'Anna, C. George, A. Miffre and P. Rairoux, UV polarization lidar for remote sensing new particles formation in the atmosphere, Opt. Exp., 22, A1009-A1022, (2014).

  5. Electrostatic analysis of the interactions between charged particles of dielectric materials

    NASA Astrophysics Data System (ADS)

    Bichoutskaia, Elena; Boatwright, Adrian L.; Khachatourian, Armik; Stace, Anthony J.

    2010-07-01

    An understanding of the electrostatic interactions that exist between charged particles of dielectric materials has applications that span much of chemistry, physics, biology, and engineering. Areas of interest include cloud formation, ink-jet printing, and the stability of emulsions. A general solution to the problem of calculating electrostatic interactions between charged dielectric particles is presented. The solution converges very rapidly for low values of the dielectric constant and is stable up to the point where particles touch. Through applications to unspecified particles with a range of size and charge ratios, the model shows that there exist distinct regions of dielectric space where particles with the same sign of charge are strongly attracted to one another.

  6. Phase diagram for stimulus-responsive materials containing dipolar colloidal particles

    NASA Astrophysics Data System (ADS)

    Goyal, Amit; Hall, Carol K.; Velev, Orlin D.

    2008-03-01

    Dipolar colloidal particles self-assemble into a rich variety of microstructures ranging from co-crystals of unusual symmetry, to open networks (gels) of cross-linked chains of particles. We use molecular dynamics computer simulation to explore the self-assembly, structure, crystallization and/or gelation of systems of colloid particles with permanent dipole moments immersed in a high-dielectric solvent. Particle-particle interactions are modeled with a discontinuous potential. The phase diagram in the temperature-packing fraction plane is calculated. Several types of phases are found in our simulations: ordered phases including face-centered-cubic, hexagonal-close-packed, and body-centered-tetragonal at high packing fractions, and fluid, string-fluid, and gel phases at low packing fractions. The very low volume fraction gel phases and the well-ordered crystal phases are promising for advanced materials applications.

  7. In situ measurements of gas/particle-phase transitions for atmospheric semivolatile organic compounds

    E-print Network

    Cohen, Ronald C.

    . Labora- tory studies typically measure the phase partitioning of semivolatile organic compounds by using atmosphere by using in situ observations of several hundred semivolatile organic compounds. Here we compare TAG measurementsto modeledpartitioningof select semivolatile organ- ic compounds. Although TAG

  8. Size distributions of atmospheric particles: Scale dependence, scattering properties of nonspherical particles and retrieval by inversion of spectral optical depth

    NASA Astrophysics Data System (ADS)

    Liu, Yangang

    As an investigation into size distributions of cloud particles from both the theoretical and instrumental points of view, this dissertation is mainly concerned with four topics. First, a systems theory is developed to study size distributions based on Shannon's maximum entropy principle and an energy barrier argument. This new theory reveals the scale-dependence of size distributions and provides an explanation for the long- existing discrepancy between observed and model-predicted size distributions. The scale-dependent behavior has many important implications for theoretical study as well as for instrumentation used in measuring size distributions. Second, a new methodology is developed to formulate the anomalous diffraction theory (ADT) for arbitrarily shaped particles. The ADT for finite circular cylinders is derived as a special application. Comparisons of ADT solutions with the rigorous T-matrix calculations are presented. The results show that the differences in extinction between ADT and exact solutions generally decrease with particle nonsphericity. A similar decrease occurs for absorption at wavelengths of relatively strong absorption, including the Christiansen bands (where the real part of the refractive index approaches unity). The results also suggest that ADT may provide an alternative to the widely used Mie theory in parameterization and remote sensing of cirrus clouds at certain wavelengths. Third, the illposedness and solution ambiguity of retrieving size distribution from multispectral extinction measurements are discussed. A new retrieval algorithm is developed to solve the illposed inverse problem; it is evaluated by comparison with an iterative algorithm and the method of truncated singular value decomposition. The influences of particle shapes and refractive indices on size distribution retrieval are investigated using the new retrieval algorithm. The effects of both the Mie theory and the new developed ADT approximation to light scattering by nonspherical particles are found to cause serious distortions of the retrieved size distributions. Similar distortions are also found when incorrect refractive indices are used. Fourth, the effects of the different factors discussed in previous chapters on size distribution retrievals are addressed. Implications for instrumentation and theoretical models are explored. The overall results of this research suggest that precautions need to be taken due to the scale-mismatch when (1) comparing observations with model predictions, (2) comparing measurements with instruments of different sampling scales, (3) coupling models that describe phenomena of different scales. Size distribution measurements should be interpreted with caution when nonspherical particles and/or refractive index errors exist. The new results also provide useful information to guide and orient future research on instrumentation as well as theoretical models of size distributions.

  9. Sterilization of Materials with a One Atmosphere Uniform Glow Discharge Plasma.*

    NASA Astrophysics Data System (ADS)

    Ku, Yongmin; Brickman, C.; Tosh, K.; Kelly-Wintenberg, K.; Montie, T. C.; Tsai, P.; Wadsworth, L.; Roth, J. Reece

    1996-11-01

    The relatively recent development of the One Atmosphere Uniform Glow Discharge Plasma sterilization technique at the UTK Plasma Science Laboratory has produced initial results which indicate that the technique may have commercial potential. We have shown that active species in a OAUGDP can be applied to the sterilization of fabrics, films, solid materials, and microbiological culture media. With a OAUGDP, we can eliminate the vacuum system which enforces batch processing and requires a continuous input of electrical power. With a OAUGDP, the exposure time is as little as 15 seconds. Sterilization of microorganisms with a kill ratio of 10E6 or higher, can be achieved with minimal unwanted byproducts and at less expense, compared to such conventional sterilization methods as autoclaving, ethylene oxide, or low pressure plasma treatment. This paper discusses the sterilization mechanisms of this new technique, and compares its advantages and disadvantages with other widely used techniques. ^1 Department of Microbiology, UTK ^2 UTK Textiles and Nonwovens Development Center (TANDEC) Research supported in part by the UTK Textiles and Nonwovens Development Center and UTK Center for Materials Processing.

  10. Development and characterization of an ion trap mass spectrometer for the on-line chemical analysis of atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Kürten, Andreas; Curtius, Joachim; Helleis, Frank; Lovejoy, Edward R.; Borrmann, Stephan

    2007-08-01

    A novel Ion Trap Aerosol Mass Spectrometer (IT-AMS) for atmospheric particles has been developed and characterized. With this instrument the chemical composition of the non-refractory component of aerosol particles can be measured quantitatively. The set-up makes use of the well-characterized inlet and vaporization/ionization system of the Aerodyne Aerosol Mass Spectrometer (AMS). While the AMS uses either a linear quadrupole mass filter (Q-AMS) or a time-of-flight mass spectrometer (ToF-AMS) as the mass analyzer, the IT-AMS utilizes a three-dimensional quadrupole ion trap. The main advantages of an ion trap are the possibility of performing MSn-experiments as well as ion/molecule reaction studies. The mass analyzer has been built in-house together with major components of the electronics. The IT-AMS is operated under full PC control and can be used as a field instrument due to its compact size. A detailed description of the set-up is presented. Experiments show that a mass resolving power larger than 1500 can be reached. This value is high enough to separate different organic species at m/z 43. Calibrations with laboratory-generated aerosol particles indicate a linear relationship between signal response and aerosol mass concentration. These studies, together with estimates of the detection limits for particulate sulfate (0.65 [mu]g/m3) and nitrate (0.16 [mu]g/m3) demonstrate the suitability of the IT-AMS to measure atmospheric aerosol particles. An inter-comparison between the IT-AMS and a Q-AMS for nitrate in urban air yields good agreement. For laboratory-generated polystyrene latex particles a MS/MS-study using collision-induced dissociation (CID) with a daughter/parent ion yield of more than 60% has been performed. In the future, similar MS/MS-studies can be conducted for atmospheric particles and for the study of secondary aerosol formation in smog chamber experiments.

  11. Physicochemical properties and ability to generate free radicals of ambient coarse, fine, and ultrafine particles in the atmosphere of Xuanwei, China, an area of high lung cancer incidence

    NASA Astrophysics Data System (ADS)

    Lu, Senlin; Yi, Fei; Hao, Xiaojie; Yu, Shang; Ren, Jingjing; Wu, Minghong; Jialiang, Feng; Yonemochi, Shinich; Wang, Qingyue

    2014-11-01

    The link between the high incidence of lung cancer and harmful pollutants emitted by local coal combustion in Xuanwei, Yunnan province, China, has been a focus of study since the 1980s. However, the mechanisms responsible for the high lung cancer rate remain unclear, necessitating further study. Since a close relationship between ambient air particle pollution and respiratory diseases exists, we sampled size-resolved ambient particles from the atmosphere of Xuanwei. In our indoor experiment, cutting-edge methods, including scanning electron microscopy coupled with energy dispersive X-ray detection (SEM/EDX), particle-induced X-ray emission (PIXE), electronic paramagnetic resonance (EPR) and the cell-free DCFH-DA assay, were employed to investigate the physicochemical properties, the potential to generate free radicals and the oxidative potential of ambient coarse (diameter, 1.8-10 ?m), fine (diameter, 0.1-1.8 ?m), and ultrafine (diameter, <0.1 ?m) particles. We found the total mass concentrations of the size-resolved particles collected in spring were higher than that in early winter. Mass percentage of fine particles accounted for 68% and 61% of the total particulate mass in spring and in early winter samples, respectively, indicating that fine particles were the major component of the Xuanwei ambient particulate matters. On the other hand, the results of SEM/EDX analysis showed that the coarse particles were dominated by minerals, the fine particles by soot aggregates and fly ashes, and the ultrafine particles by soot particles and unidentified particles. Our PIXE results revealed that crustal elements (Ca, Ti Si, Fe) were mainly distributed in coarse particles, while trace metals (Cr, Mn, Ni, Cu, Zn, Pb) dominated in the fine particle fraction, and S, a typical element emitted by coal combustion, mainly resided in fine particles collected from the winter atmosphere. EPR results indicated that the magnitude of free radical intensity caused by size-resolved particles followed these patterns: fine particles > coarse particles > ultrafine particles for spring samples and ultrafine particles > fine particles > coarse particles for winter samples. Cell-free DCFH assay results conclusively showed that all of the measured particle suspensions displayed a higher oxidative potential than the negative control. The correlation coefficient (R2) between free radical intensity and fluorescent intensity generated by the size-resolved particles was 0.535 and 0.507 for the spring and winter seasons, respectively, implying that ambient air particles in the Xuanwei atmosphere have the ability to generate free radicals, and fine and ultrafine particles could be hazardous to local residents.

  12. Particle-Phase Chemistry of Secondary Organic Material: Modeled Compared to Measured O:C and H:C Elemental Ratios Provide Constraints

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Liu, Y.; Donahue, N. M.; Shilling, J. E.; Martin, S. T.

    2011-12-01

    Secondary organic material (SOM) produced by the oxidation of biogenic volatile organic compounds is a major global contributor to the mass concentrations of organic components of atmospheric particles. Chemical mechanisms of SOM production are typically developed in focused laboratory studies but widely used in the complex modeling context of the atmosphere. Given this extrapolation, it is crucial to use multidimensional data constraints for testing the accuracy of the chemical mechanisms. Particle mass yield is a typical standard for model-measurement comparison. Particle composition expressed as O:C and H:C elemental ratios can serve as a higher dimensional constraint. A paradigm that uses the two constraints is presented in this study for SOM production from an important C5-C10-C15 terpene sequence, namely isoprene, ?-pinene, and ?-caryopyhllene. The model MCM-SIMPOL is introduced based on the Master Chemical Mechanism (MCM v3.2) and a group contribution method for vapor pressures (SIMPOL). The O:C and H:C ratios of the SOM are measured using an Aerosol Mass Spectrometer (AMS). Detailed SOM-specific AMS calibrations indicate that published O:C and H:C ratios for SOM are systematically too low. Overall, the measurement-model gap was small for particle mass yield but significant for particle-average elemental composition. The implication is that a key chemical pathway is missing from the chemical mechanism. The data can be explained by the particle-phase homolytic decomposition of organic hydroperoxides and subsequent alkyl-radical-promoted oligomerization. For climate-related modeling such as the aerosol direct effect, mass-based modeling is the norm. In this regard, the model might be concluded as acceptably accurate based on the one-dimensional model-measurement comparison on yield; yet, the further analysis proves that the model mechanism is missing important particle-phase chemistry that possibly controls the physical properties of the particles.

  13. Thermal stability of composite phase change material microcapsules incorporated with silver nano-particles

    Microsoft Academic Search

    Qingwen Song; Yi Li; Jianwei Xing; J. Y. Hu; Yuen Marcus

    2007-01-01

    This paper reports a study on the thermal stability of phase change material microcapsules that are incorporated with silver nano-particles (Ag-NPs). The novel microcapsules were fabricated by the technique of in situ polymerization, with aminoplast as the wall and phase change material bromo-hexadecane (PCM BrC16) as the core. Thermal gravimetry (TG) analysis was applied to measure the thermal stability of

  14. Surface-quaternized chitosan particles as an alternative and effective organic antibacterial material.

    PubMed

    Wiarachai, Oraphan; Thongchul, Nuttha; Kiatkamjornwong, Suda; Hoven, Voravee P

    2012-04-01

    Taking advantage of the large surface area that is covered with permanent positive charges of quaternary ammonium entities, this research aimed to develop environmentally friendly, organic antibacterial material from quaternized chitosan particles that may be applicable for biomedical devices, health and textile industries. The particles were formulated by ionic crosslinking of chitosan with tripolyphosphate followed by quaternization under heterogeneous conditions, via either direct methylation or reductive N-alkylation with a selected aldehyde followed by methylation. Sub-micron, spherical and positively charged quaternized chitosan particles were formed, as determined by (1)H NMR, FT-IR, PCS and TEM analysis. Antibacterial activity tests, performed by viable cell (colony) counts, suggested that all quaternized chitosan particles exhibited superior antibacterial activity against the model Gram-positive bacteria, Staphylococcus aureus, as compared to the native chitosan particles at neutral pH. Only some quaternized chitosan particles, especially those having a high charge density and bearing large alkyl substituent groups, were capable of suppressing the growth of the model Gram-negative bacteria, Escherichia coli. The inhibitory efficiency of the quaternized chitosan particles was quantified in terms of the minimum inhibitory concentration (MIC). Damaging impact of the quaternized chitosan particles on the bacteria was also qualitatively determined by microscopic observation of the bacterial morphology. PMID:22197736

  15. Development of vapor deposited silica sol-gel particles for use as a bioactive materials system.

    PubMed

    Snyder, Katherine L; Holmes, Hallie R; VanWagner, Michael J; Hartman, Natalie J; Rajachar, Rupak M

    2013-06-01

    Silica-based sol-gel and bioglass materials are used in a variety of biomedical applications including the surface modification of orthopedic implants and tissue engineering scaffolds. In this work, a simple system for vapor depositing silica sol-gel nano- and micro-particles onto substrates using nebulizer technology has been developed and characterized. Particle morphology, size distribution, and degradation can easily be controlled through key formulation and manufacturing parameters including water:alkoxide molar ratio, pH, deposition time, and substrate character. These particles can be used as a means to rapidly modify substrate surface properties, including surface hydrophobicity (contact angle changes >15°) and roughness (RMS roughness changes of up to 300 nm), creating unique surface topography. Ions (calcium and phosphate) were successfully incorporated into particles, and induced apatitie-like mineral formation upon exposure to simulated body fluid Preosteoblasts (MC3T3) cultured with these particles showed up to twice the adhesivity within 48 h when compared to controls, potentially indicating an increase in cell proliferation, with the effect likely due to both the modified substrate properties as well as the release of silica ions. This novel method has the potential to be used with implants and tissue engineering materials to influence cell behavior including attachment, proliferation, and differentiation via cell-material interactions to promote osteogenesis. PMID:23585242

  16. Characteristics of atmospheric organic and elemental carbon particle concentrations in Los Angeles

    Microsoft Academic Search

    H. Andrew. Gray; Glen R. Cass; James J. Huntzicker; Emily K. Heyerdahl; John A. Rau

    1986-01-01

    A fine particle air monitoring network was operated in the Los Angeles area during 1982. It was found that carbonaceous aerosols accounted for typically 40% of total fine particle mass loadings at most monitoring sites. The ratio of total carbon (TC) to elemental carbon (EC) in ambient samples and in primary source emissions was examined as an indicator of the

  17. Heterogeneous chemistry of atmospheric mineral dust particles and their resulting cloud-nucleation properties

    E-print Network

    Sullivan, Ryan Christopher

    2008-01-01

    using LDI with a 266 nm UV laser pulse. Particles composedQ-switched Nd:YAG laser (4 th harmonic, 266 nm). The lasers266 nm than CaCO 3 , and therefore particles containing Ca(NO 3 ) 2 will tend to absorb more laser

  18. Toward Quantifying the Mass-Based Hygroscopicity of Individual Submicron Atmospheric Aerosol Particles with STXM/NEXAFS and SEM/EDX

    NASA Astrophysics Data System (ADS)

    Yancey Piens, D.; Kelly, S. T.; OBrien, R. E.; Wang, B.; Petters, M. D.; Laskin, A.; Gilles, M. K.

    2014-12-01

    The hygroscopic behavior of atmospheric aerosols influences their optical and cloud-nucleation properties, and therefore affects climate. Although changes in particle size as a function of relative humidity have often been used to quantify the hygroscopic behavior of submicron aerosol particles, it has been noted that calculations of hygroscopicity based on size contain error due to particle porosity, non-ideal volume additivity and changes in surface tension. We will present a method to quantify the hygroscopic behavior of submicron aerosol particles based on changes in mass, rather than size, as a function of relative humidity. This method results from a novel experimental approach combining scanning transmission x-ray microscopy with near-edge x-ray absorption fine spectroscopy (STXM/NEXAFS), as well as scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDX) on the same individual particles. First, using STXM/NEXAFS, our methods are applied to aerosol particles of known composition ? for instance ammonium sulfate, sodium bromide and levoglucosan ? and validated by theory. Then, using STXM/NEXAFS and SEM/EDX, these methods are extended to mixed atmospheric aerosol particles collected in the field at the DOE Atmospheric Radiation Measurement (ARM) Climate Research Facility at the Southern Great Planes sampling site in Oklahoma, USA. We have observed and quantified a range of hygroscopic behaviors which are correlated to the composition and morphology of individual aerosol particles. These methods will have implications for parameterizing aerosol mixing state and cloud-nucleation activity in atmospheric models.

  19. Free fatty acid particles in protein formulations, part 2: contribution of polysorbate raw material.

    PubMed

    Siska, Christine C; Pierini, Christopher J; Lau, Hollis R; Latypov, Ramil F; Fesinmeyer, R Matthew; Litowski, Jennifer R

    2015-02-01

    Polysorbate 20 (PS20) is a nonionic surfactant frequently used to stabilize protein biopharmaceuticals. During the development of mAb formulations containing PS20, small clouds of particles were observed in solutions stored in vials. The degree of particle formation was dependent on PS20 concentration. The particles were characterized by reversed-phase HPLC after dissolution and labeling with the fluorescent dye 1-pyrenyldiazomethane. The analysis showed that the particles consisted of free fatty acids (FFAs), with the distribution of types consistent with those found in the PS20 raw material. Protein solutions formulated with polysorbate 80, a chemically similar nonionic surfactant, showed a substantial delay in particle formation over time compared with PS20. Multiple lots of polysorbates were evaluated for FFA levels, each exhibiting differences based on polysorbate type and lot. Polysorbates purchased in more recent years show a greater distribution and quantity of FFA and also a greater propensity to form particles. This work shows that the quality control of polysorbate raw materials could play an important role in biopharmaceutical product quality. PMID:25196966

  20. Study of particle rebound characteristics and material erosion at high temperature

    SciTech Connect

    Tabakoff, W.; Hamed, A.; Eroglu, H.

    1988-12-01

    The rebound characteristics of 15 micron mean diameter fly ash particles impacting several target materials were measured using Laser Doppler Velocimetry (LDV). Detailed results including the effects of various parameters were given in a previous report. This report focuses on the effects of new additional parameters on the rebound characteristics. First, the restitution parameters are reported at small impact angles (less than 15 degrees) for 410 stainless steel, 2024 aluminum, 6Al-4V titanium, INCO 718, RENE 41, AM 355, L605 cobalt and alumina (Al/sub 2/O/sub 3/). The fly ash rebound data for these target materials are then investigated in an effort to develop generalized correlations for the restitution coefficients. The effect of the target surface geometry on the rebound characteristics is investigated for 2024 aluminum as the next step. Finally, three-dimensional (3-D) rebound characteristics are presented for fly ash particles impacting INCO 718 and 2024 aluminum target materials. Semiempirical erosion rate equations are reported for 2024 aluminum, INCO 718, RENE 41 and AM355 alloys from the experimental erosion results for fly ash and silica sand particles at various particle velocities and material temperatures. 18 refs., 86 figs.

  1. Harnessing Labile Bonds between Nanogels Particles to Create Self-Healing Materials

    Microsoft Academic Search

    German V. Kolmakov; Krzysztof Matyjaszewski; Anna C. Balazs

    2009-01-01

    Using computational modeling, we demonstrate the self-healing behavior of novel materials composed of nanoscopic gel particles that are interconnected into a macroscopic network by both stable and labile bonds. Under mechanical stress, the labile bonds between the nanogels can break and readily reform with reactive groups on neighboring units. This breaking and reforming allows the units in the network to

  2. SINGLE PARTICLE IMPACT BREAKAGE CHARACTERIZATION OF MATERIALS BY DROP WEIGHT TESTING

    Microsoft Academic Search

    Ömürden GENÇ; Levent ERGÜN; Hakan BENZER

    2004-01-01

    A drop weight tester was designed for the purpose of analyzing single particle impact breakage characteristics of different materials. Test results were evaluated through the breakage distributions of different size fractions at various impact energy levels. Breakage parameter t10 (Narayanan, 1986) is used to represent the degree of size reduction which is assumed to be represantative of the breakage product

  3. Fracture and wear of composite materials in interaction with a stream of abrasive particles

    Microsoft Academic Search

    T. D. Karimbaev; Yu. A. Nozhnitskii; V. I. Gundarov; L. S. Rysin; V. G. Lyuttsai; I. A. Tarasov

    1980-01-01

    In the present work, an experimental study was made of the abrasive erosion of several composite materials and coatings based on polymers, carbon, and metals, and reinforced with glass, carbon, boron, and organic fibers, strips and cloths made of these fibers, whiskers, particles, and metal netting. For the sake of comparison, we also tested several metal alloys widely used in

  4. Material removal mechanism of ceria particles with different sizes in glass polishing

    NASA Astrophysics Data System (ADS)

    Peng, Wenqiang; Guan, Chaoliang; Li, Shengyi

    2014-03-01

    A material removal mechanism of ceria particles with different sizes in a glass polishing process was investigated in detail. Contrast polishing experiments were carried out using ceria slurries with two kinds of particle sizes and different amounts of hydrogen peroxide (H2O2) added in the slurries. The Ce3+ ions on the surface of the ceria particles were gradually oxidized to Ce with increased H2O2 concentration. It was found that the material removal rate (MRR) decreased sharply with an increasing concentration of H2O2. There was no material removal when the concentration reached 2.0% for nanoparticle slurry. Nevertheless, the application of microparticles made the MRR decrease to a constant value when excessive H2O2 was added. By comparison, we conclude that the material is removed by chemical reaction for ceria nanoparticles, while chemical reaction and mechanical abrasion simultaneously take place for ceria particles with sizes at scale of micrometers in the glass polishing process. It is clearly demonstrated from the experimental results that Ce instead of Ce ions play an important role in chemically reacting with the glass surface. An ultrasmooth surface with root-square-mean roughness of 0.272 nm was obtained after being polished by ceria nanoparticles.

  5. Sieveless particle size distribution analysis of particulate materials through computer vision

    SciTech Connect

    Igathinathane, C. [Mississippi State University (MSU); Pordesimo, L. O. [Mississippi State University (MSU); Columbus, Eugene P [ORNL; Batchelor, William D [ORNL; Sokhansanj, Shahabaddine [ORNL

    2009-05-01

    This paper explores the inconsistency of length-based separation by mechanical sieving of particulate materials with standard sieves, which is the standard method of particle size distribution (PSD) analysis. We observed inconsistencies of length-based separation of particles using standard sieves with manual measurements, which showed deviations of 17 22 times. In addition, we have demonstrated the falling through effect of particles cannot be avoided irrespective of the wall thickness of the sieve. We proposed and utilized a computer vision with image processing as an alternative approach; wherein a user-coded Java ImageJ plugin was developed to evaluate PSD based on length of particles. A regular flatbed scanner acquired digital images of particulate material. The plugin determines particles lengths from Feret's diameter and width from pixel-march method, or minor axis, or the minimum dimension of bounding rectangle utilizing the digital images after assessing the particles area and shape (convex or nonconvex). The plugin also included the determination of several significant dimensions and PSD parameters. Test samples utilized were ground biomass obtained from the first thinning and mature stand of southern pine forest residues, oak hard wood, switchgrass, elephant grass, giant miscanthus, wheat straw, as well as Basmati rice. A sieveless PSD analysis method utilized the true separation of all particles into groups based on their distinct length (419 639 particles based on samples studied), with each group truly represented by their exact length. This approach ensured length-based separation without the inconsistencies observed with mechanical sieving. Image based sieve simulation (developed separately) indicated a significant effect (P < 0.05) on number of sieves used in PSD analysis, especially with non-uniform material such as ground biomass, and more than 50 equally spaced sieves were required to match the sieveless all distinct particles PSD analysis. Results substantiate that mechanical sieving, owing to handling limitations and inconsistent length-based separation of particles, is inadequate in determining the PSD of non-uniform particulate samples. The developed computer vision sieveless PSD analysis approach has the potential to replace the standard mechanical sieving. The plugin can be readily extended to model (e.g., Rosin Rammler) the PSD of materials, and mass-based analysis, while providing several advantages such as accuracy, speed, low cost, automated analysis, and reproducible results.

  6. Elemental analysis by PIXE and other IBA techniques and their application to source fingerprinting of atmospheric fine particle pollution

    NASA Astrophysics Data System (ADS)

    Cohen, David D.; Bailey, Grahame M.; Kondepudi, Ramesh

    1996-04-01

    The PIXE technique in conjunction with PIGME, PESA and RBS has been used to routinely measure over 20 different elements present in fine particle atmospheric samples. PIXE provided data for selected elements from Al to U while the other techniques provided information on elements lighter than Al such as H, C, N, O, F and Na. Detection limits for the ion beam techniques on Teflon filter papers were typically between 0.02 and 0.2 ?g/cm 2 for a few minutes of accelerator running time. The multi-elemental capability of PIXE enabled us to use these 20 or so different elemental measurements to define fingerprints for various fine particle sources. These fingerprints included anthropogenic sources such as motor vehicles, industry and coal combustion as well as natural sources such as seaspray and soil.

  7. The Effects of Particle Size, Relative Humidity, and Sulfur Dioxide on Iron Solubility in Atmospheric Particulate Matter

    NASA Astrophysics Data System (ADS)

    Cartledge, B. T.; Marcotte, A.; Anbar, A. D.; Herckes, P.; Majestic, B. J.

    2014-12-01

    The current study focuses on studying how iron (Fe) solubility is affected by particle size, relative humidity, and exposure to sulfur dioxide (SO2). Fe, the most abundant transition metal in atmospheric particulate matter, plays a critical role in the atmospheric sulfur cycle and is a micronutrient for phytoplankton in remote regions of the ocean. To mimic oceanic particles, iron-containing minerals (hematite, magnetite, goethite, and illite) were resuspended with sodium chloride and size-segregated on Teflon filters into five different size fractions: 10-2.5 ?m, 2.5-1.0 ?m, 1.0-0.5 ?m, 0.5-0.25 ?m, and <0.25 ?m. Mineral phases were then exposed to 5 ppm SO2 in air at marine environment humidity (>80%) and arid environment humidity (24%). Trials with no SO2 ­were also performed as comparisons. Total Fe was determined by using microwave-assisted acid digestion and soluble Fe was determined by extracting the samples in a simulated cloud water buffer (pH 4.25, 0.5 mM acetate, 0.5 mM formate, and 0.2 mM ammonium nitrate). Both total and soluble Fe concentrations were determined via inductively-coupled plasma mass spectrometry (ICP-MS). We found that, as particle size decreased, Fe percent solubility increased for hematite, magnetite, and goethite. The percent solubility of Fe in these mineral phases steadily increased from 0.5-10% as particle size decreased. In contrast, the Fe percent solubility in illite was relatively constant for the largest four size fractions but increased dramatically in the smallest size fraction. The percent solubility of Fe in illite ranged from 5-20% as the particle size decreased. Additionally, increased Fe solubility was linked to increased relative humidity with higher percent solubility generally observed in all mineral phases for the samples exposed at the higher humidity. No correlation was observed for the effects of the SO2 on Fe percent solubility. The likely lack of Fe-SO2 interactions were also supported by synchrotron-based x-ray spectroscopy. These results help further the knowledge of how the solubilization of particulate Fe is affected by atmospheric transport.

  8. A study of inter-particle bonds in dry bauxite waste resulting in atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Wagh, Arun S.; Thompson, Bentley

    1988-02-01

    Bauxite and Alumina production are one of the main activities of several third world countries such as Jamaica, Brazil, India, Guinea, eastern European countries such as Hungary and Rumania and advanced countries such as Australia, West Germany, Japan and the United States. The mining operations lead to dust pollution, but the refining of bauxite to alumina yield large amounts of highly caustic sludge waste, called "Red Mud". Millions of tons of the waste produced in every country are stored in containment dams or natural valleys. This leads to ground water pollution, destruction of plant and bird life and is hazardous to human settlement in earthquake prone regions like Jamaica. As a result several companies have been looking into dry mud stacking which involves thickening the mud in the refining plants and sprying it on the slopes to sun dry it. Typically it involves a drying field of about two hundred acres, which could act as a potential source of caustic dust. In Jamaica one company has started disposing of the mud in this way. The aerosol formation from such areas depends mainly on the integrity of the top dry layers. Presently this is done by studying the approximate parameters such as the friability of the mud. However, following the recent advances in powder technology it has been possible for us to develop an instrument to study the average interparticle forces between the red mud particles. The instrument is based on the principle of a tensometer and a split cell is used to load specimens. A load cell is used to measure the force and a chart recorder is used for plotting separation and the force. The present study reports elemental composition of the dust and its health hazards. It also reports the physical measurement of the average interparticle force as a function of their separation in the Jamaican mud. The effect of ultraviolet radiation on the strength of the material is studied to see the effect of sun-drying of the waste. The five-fold increase in tensile strength indicates that laterisation process is responsible for this phenomenon in Jamaican red mud. The study is crucial to the development of dust free mud stacking by the proper modifications in the process technology. Finally, such a case study is general enough in the characterisation of other sources of aerosols.

  9. Energetic particle precipitation into the middle atmosphere triggered by a coronal mass ejection

    Microsoft Academic Search

    Mark A. Clilverd; Craig J. Rodger; Robyn M. Millan; John G. Sample; Michael Kokorowski; Michael P. McCarthy; Thomas Ulich; Tero Raita; Andrew J. Kavanagh; Emma Spanswick

    2007-01-01

    Precipitation of relativistic electrons into the atmosphere has been suggested as the primary loss mechanism for radiation belt electrons during large geomagnetic storms. Here we investigate the geographical spread of precipitation as a result of the arrival of a coronal mass ejection (CME) on 21 January 2005. In contrast to previous statistical studies we provide one of the first attempts

  10. A condensation-growth and impaction method for rapid off-line chemical-characterization of organic submicrometer atmospheric aerosol particles

    Microsoft Academic Search

    Berko Sierau; Frank Stratmann; Matthias Pelzing; Christian Neusüß; Diana Hofmann; Martin Wilck

    2003-01-01

    An off-line method for rapid analysis of submicrometer organic atmospheric aerosol particles was developed. The method first uses condensational growth of submicrometer particles and then impaction to collect the particles for off-line chemical analysis. This condensation-growth and impaction system (C-GIS) converts the aerosol into a hydrosol that can be readily drawn into a variety of systems for chemical analysis. The

  11. Effect of cluster\\/particle deposition on atmospheric pressure chemical vapor deposition of SiO2 from four gaseous organic Si-containing precursors and ozone

    Microsoft Academic Search

    Toshiyuki Fujimoto; Kikuo Okuyama; Satoshi Yamada; Motoaki Adachi

    1999-01-01

    In order to analyze the particle generation and its effect on the SiO2 thin film in an atmospheric pressure chemical vapor deposition (APCVD) process using four organic silicon vapors and ozone gas, gas-phase particle generation, growth, transportation and vapor-cluster\\/particle codeposition processes were studied experimentally and theoretically using a flow-type vertical tube reactor. Decomposition reaction rates of four organic silicon vapors

  12. Transport of ablated material through a water vapor atmosphere in pulsed laser deposition of hydroxylapatite

    NASA Astrophysics Data System (ADS)

    Arias, J. L.; Mayor, M. B.; Pou, J.; León, B.; Pérez-Amor, M.

    2002-01-01

    Hydroxylapatite (Ca 10(PO 4) 6(OH) 2) is a calcium phosphate used as a coating for dental and orthopaedical implants, because its composition and structure is similar to the mineral part of bone. As an alternative to the traditional plasma spray coating technique, pulsed laser deposition (PLD) has been applied. A hydroxylapatite target was ablated with an ArF laser in a water vapor pressure of 45 Pa to investigate the transport of the ablated material to the substrate. The substrate was placed at different distances from the target, inside and outside the plume. The distribution of coating thickness was measured by profilometry. The Ca/P ratio of the coatings was measured by EDAX, whereas their OH - and CO 32- content was evaluated by FT-IR spectroscopy. Inside the plume the thickness distributions correspond to an adiabatic expansion, while outside there is a diffusion of the species through the water vapor atmosphere to the substrate. The composition of the coatings also confirms this behavior.

  13. Atmospheric Aerosols Aging Involving Organic Compounds and Impacts on Particle Properties 

    E-print Network

    Qiu, Chong

    2013-02-01

    coating grows, suggesting a compaction of the soot morphology. As the organic coating grows, the particles become more hygroscopic and have enhanced light scattering and absorption. The second part discusses the potential reactions between amines and some...

  14. PARTICLES OF DIFFERENCE.

    SciTech Connect

    SCHWARTZ,S.E.

    2000-09-21

    It is no longer appropriate, if it ever was, to think of atmospheric aerosols as homogeneous spheres of uniform composition and size. Within the United States, and even more globally, not only the mass loading but also the composition, morphology, and size distribution of atmospheric aerosols are highly variable, as a function of location, and at a given location as a function of time. Particles of a given aerodynamic size may differ from one another, and even within individual particles material may be inhomogeneously distributed, as for example, carbon spherules imbedded in much larger sulfate particles. Some of the particulate matter is primary, that is, introduced into the atmosphere directly as particles, such as carbon particles in diesel exhaust. Some is secondary, that is, formed in the atmosphere by gas-to-particle conversion. Much of the material is inorganic, mainly sulfates and nitrates resulting mainly from energy-related emissions. Some of the material is carbonaceous, in part primary, in part secondary, and of this material some is anthropogenic and some biogenic. While the heterogeneity of atmospheric aerosols complicates the problem of understanding their loading and distribution, it may well be the key to its solution. By detailed examination of the materials comprising aerosols it is possible to infer the sources of these materials. It may be possible as well to identify specific health impairing agents. The heterogeneity of aerosol particles is thus the key to identifying their sources, to understanding the processes that govern their loading and properties, and to devising control strategies that are both effective and efficient. Future research must therefore take cognizance of differences among aerosol particles and use these differences to advantage.

  15. Seasonal variation of source contributions to atmospheric fine and coarse particles at suburban area in Istanbul, Turkey

    SciTech Connect

    Karaca, F.; Alagha, O.; Erturk, F.; Yilmaz, Y.Z.; Ozkara, T. [Fatih University, Istanbul (Turkey). Dept. for Environmental Engineering

    2008-06-15

    Daily samples of fine (PM2.5) and coarse (PM2.5-10) particles were collected from July 2002 to July 2003 to provide a better understanding of the elemental concentration and source contribution to both PM fractions. Sampling location represents suburban part of Istanbul metropolitan city. Samples were collected on Teflon filters using a 'Dichotomous Sampler.' Concentrations of Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V, and Zn were measured by GFAAS, FAAS, and FAES techniques. Elemental variations of heating and nonheating seasons were discussed. Fossil fuel-related atmospheric metals dramatically increased during the heating season, while natural originated atmospheric metals increased during the nonheating season. Seasonal variations of source contributions were evaluated using factor analysis, which was separately applied to the collected fine and coarse particles data sets during heating and nonheating seasons (four data sets: PM2.5 heating, PM2.5 nonheating, PM2.5-10 heating, and PM2.5-10 nonheating). Significant seasonal differences in source contributions were observed. Four factor groups were extracted for PM2.5 dataset during the nonheating season, while five factor groups were extracted for all the other cases. Mineral dust transportation, traffic, and industry-related activities were classified as different factor groups in all the cases.

  16. Seasonality and interspecies differences in particle/gas partitioning of PAHs observed by the Integrated Atmospheric Deposition Network (IADN)

    NASA Astrophysics Data System (ADS)

    Galarneau, Elisabeth; Bidleman, Terry F.; Blanchard, Pierrette

    This study presents partitioning data from eight locations in the Laurentian Great Lakes region collected by the Integrated Atmospheric Deposition Network (IADN) over periods ranging from 1 to 6 years. Particle/gas partitioning varies sufficiently between sites in the Great Lakes region to preclude the use of a uniform temperature dependence for its description. Site-specific parameters for describing partitioning as a function of inverse temperature are presented. Relationships between partitioning of appreciably semivolatile PAHs and saturated vapour pressure at Chicago (IIT) and Sturgeon Point (STP) demonstrate that anthracene, benz[a]anthracene and retene behave differently than phenanthrene, fluoranthene, pyrene and chrysene+triphenylene. Possible reasons for these differences include interspecies variations in the fraction of atmospherically non-exchangeable, though analytically extractable, PAHs on particles and differences in soot-air partition coefficients as they relate to saturated vapour pressure. The observed interspecies differences are not consistent with sampling artefacts such as filter adsorption or sorbent breakthrough. At IIT, but not at STP, values of the slope of the relationship between the log partition coefficient and log vapour pressure vary in a manner opposing the annual temperature cycle. A comparison of partitioning calculated by a combined absorption/adsorption model shows good predictability at Chicago but underestimates values at a rural site (Eagle Harbor, EGH) by an order of magnitude.

  17. Particle-in-cell and global simulations of ? to ? transition in atmospheric pressure Penning-dominated capacitive discharges

    NASA Astrophysics Data System (ADS)

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.; Chabert, P.; Lazzaroni, C.

    2014-06-01

    Atmospheric pressure radio-frequency (rf) capacitive micro-discharges are of interest due to emerging applications, especially in the bio-medical field. A previous global model did not consider high-power phenomena such as sheath multiplication, thus limiting its applicability to the lower power range. To overcome this, we use one-dimensional particle-in-cell (PIC) simulations of atmospheric He/0.1% N2 capacitive discharges over a wide range of currents and frequencies to guide the development of a more general global model which is also valid at higher powers. The new model includes sheath multiplication and two classes of electrons: the higher temperature ‘hot’ electrons associated with the sheaths, and the cooler ‘warm’ electrons associated with the bulk. The electric field and the electron power balance are solved analytically to determine the time-varying hot and warm temperatures and the effective rate coefficients. The particle balance equations are integrated numerically to determine the species densities. The model and PIC results are compared, showing reasonable agreement over the range of currents and frequencies studied. They indicate a transition from an ? mode at low power characterized by relatively high electron temperature Te with a near uniform profile to a ? mode at high power with a Te profile strongly depressed in the bulk plasma. The transition is accompanied by an increase in density and a decrease in sheath widths. The current and frequency scalings of the model are confirmed by the PIC simulations.

  18. The Impact of Particle Size, Relative Humidity, and Sulfur Dioxide on Iron Solubility in Simulated Atmospheric Marine Aerosols.

    PubMed

    Cartledge, Benton T; Marcotte, Aurelie R; Herckes, Pierre; Anbar, Ariel D; Majestic, Brian J

    2015-06-16

    Iron is a limiting nutrient in about half of the world's oceans, and its most significant source is atmospheric deposition. To understand the pathways of iron solubilization during atmospheric transport, we exposed size segregated simulated marine aerosols to 5 ppm sulfur dioxide at arid (23 ± 1% relative humidity, RH) and marine (98 ± 1% RH) conditions. Relative iron solubility increased as the particle size decreased for goethite and hematite, while for magnetite, the relative solubility was similar for all of the fine size fractions (2.5-0.25 ?m) investigated but higher than the coarse size fraction (10-2.5 ?m). Goethite and hematite showed increased solubility at arid RH, but no difference (p > 0.05) was observed between the two humidity levels for magnetite. There was no correlation between iron solubility and exposure to SO2 in any mineral for any size fraction. X-ray absorption near edge structure (XANES) measurements showed no change in iron speciation [Fe(II) and Fe(III)] in any minerals following SO2 exposure. SEM-EDS measurements of SO2-exposed goethite revealed small amounts of sulfur uptake on the samples; however, the incorporated sulfur did not affect iron solubility. Our results show that although sulfur is incorporated into particles via gas-phase processes, changes in iron solubility also depend on other species in the aerosol. PMID:26000788

  19. Source apportionment of atmospheric PAHs and their toxicity using PMF: Impact of gas/particle partitioning

    NASA Astrophysics Data System (ADS)

    Gao, Bo; Wang, Xin-Ming; Zhao, Xiu-Ying; Ding, Xiang; Fu, Xiao-Xin; Zhang, Yan-Li; He, Quan-Fu; Zhang, Zhou; Liu, Teng-Yu; Huang, Zou-Zhao; Chen, Lai-Guo; Peng, Yan; Guo, Hai

    2015-02-01

    24-h PM2.5 samples were simultaneously collected at six sites in a subtropical city of South China during November-December, 2009. Particle-phase concentrations of polycyclic aromatic hydrocarbons (PAHs) and organic tracers such as hopanes for vehicular emissions (VE), levoglucosan for biomass burning (BB) and picene for coal combustion (CC) were determined. Meanwhile, their gas-phase concentrations were calculated from gas/particle (G/P) partitioning theory using the particle-phase concentrations. The 4 ring PAHs (fluoranthene to chrysene) had lower particle-phase fractions (10%-79%) than other species. Estimated BaPeq and lifetime cancer risk for particle-only (P-only) vs gas + particle (G + P) data sets showed similar values, indicating PAHs with 5-7 rings dominated the carcinogenicity of PAHs. Positive Matrix Factorization (PMF) was applied on both P-only and G + P data sets to estimate the source contributions to PAHs and their toxicity. Three common sources were identified: VE, BB and CC, with CC as the most significant source for both particulate (58%) and total (G + P, 40%) PAHs. While CC exhibited consistent contributions to BaPeq for P-only (66%) vs G + P (62%) solutions, VE and BB contributions were under- and overestimated by 68% and 47%, respectively by the P-only solution, as compared to the G + P solution. The results provide an insight on the impact of G/P partitioning on the source apportionment of PAHs and their toxicity.

  20. Properties and toxicological effects of particles from the interaction between tyres, road pavement and winter traction material.

    PubMed

    Gustafsson, Mats; Blomqvist, Göran; Gudmundsson, Anders; Dahl, Andreas; Swietlicki, Erik; Bohgard, Mats; Lindbom, John; Ljungman, Anders

    2008-04-15

    In regions where studded tyres and traction material are used during winter, e.g. the Nordic countries, northern part of USA, Canada, and Japan, mechanically generated particles from traffic are the main reason for high particle mass concentrations in busy street and road environments. In many Nordic municipalities the European environmental quality standard for inhalable particles (PM(10)) is exceeded due to these particles. In this study, particles from the wear of studded and studless friction tyres on two pavements and traction sanding were generated using a road simulator. The particles were characterized using particle sizers, Particle Induced X-Ray Emission Analysis and electron microscopy. Cell studies were conducted on particles sampled from the tests with studded tyres and compared with street environment, diesel exhaust and subway PM(10), respectively. The results show that in the road simulator, where resuspension is minimized, studded tyres produce tens of times more particles than friction tyres. Chemical analysis of the sampled particles shows that the generated wear particles consist almost entirely of minerals from the pavement stone material, but also that Sulfur is enriched for the submicron particles and that Zink is enriched for friction tyres for all particles sizes. The chemical data can be used for source identification and apportionment in urban aerosol studies. A mode of ultra-fine particles was also present and is hypothesised to originate in the tyres. Further, traction material properties affect PM(10) emission. The inflammatory potential of the particles from wear of pavements seems to depend on type of pavement and can be at least as potent as diesel exhaust particles. The results imply that there is a need and a good potential to reduce particle emission from pavement wear and winter time road and street operation by adjusting both studded tyre use as well as pavement and traction material properties. PMID:18258284

  1. Exploratory study for estimating atmospheric low level particle pollution based on vertical integrated optical measurements

    NASA Astrophysics Data System (ADS)

    Yahi, Houda; Santer, Richard; Weill, Alain; Crepon, Michel; Thiria, Sylvie

    2011-07-01

    We present a method for retrieving atmospheric particulate matter (PM10) from sun-sky photometer measurements (AOT). As PM10 is a "surface parameter" and AOT is an "integrated parameters", we first determined whether a "functional relationship" linking these two quantities exists. Since these two parameters strongly depend on atmospheric structures and meteorological variables, we classified the meteorological situations in terms of weather types by using a neuronal classifier (Self organizing Map). For each weather type, we found that a relationship between AOT and PM10 can be established. We applied this approach to the Lille region (France) for the summer 2007 and then extended to a five summer period (summers of the years 2003-2007) in order to increase the statistical confidence of the PM10 retrieval from AOT measurements. The good performances of the method led us to envisage the possibility of deriving the PM10 from satellite observations.

  2. The origin of atmospheric particles in Paris: a view through carbon and lead isotopes

    NASA Astrophysics Data System (ADS)

    Widory, David; Roy, Stéphane; Le Moullec, Yvon; Goupil, Ghislaine; Cocherie, Alain; Guerrot, Catherine

    The origin of particulate matter in the urban atmosphere and the impact of its various sources are still subject to debate. This uncertainty cannot be alleviated by the sole use of 'classic' chemical parameters, creating a need for complementary indexes. We show that the use of coupled carbon and lead isotopes allows the identification of aerosol sources in the atmosphere of Paris, permitting a semi-quantification of their respective contributions. The two study sites, representative of background pollution and the influence of heavy road traffic, both show the domination of diesel exhaust fumes to the level of carbon in aerosols (either PM 2.5 or PM 10), while industry is the main vector for lead, with a contribution generally superior to 50%. Within the last 10 years, the origin of the inorganic phase shifted from road traffic towards industrial activities.

  3. Responses of the Jovian Atmosphere to Cometary Particles and Photon Impacts

    NASA Technical Reports Server (NTRS)

    Dalgarno, Alex

    2001-01-01

    Detailed calculations were performed of the deposition of energetic oxygen ions into the atmosphere of Jupiter. A Monte Carlo simulation was used. Similar processes occur in other astrophysical environments to which our methods can be applied. In particular Cravens has suggested that the X-ray emissions seen from comets are due to transitions from excited states following capture of electrons by solar wind ions colliding with the atmosphere of the comet. Alternative proposals have been advanced for the source of the cometary X-rays. We have carried out a study of the spectra and have shown that with the spectral resolution of about 20 eV the different excitation mechanisms can be distinguished. The response of the two components of the solar wind predict a spectrum that is consistent with the cometary observations. X-rays from the comets arise from the slow solar wind.

  4. On the Quantum-Classical Character of the Quantum Wavefunction of Material Particles

    E-print Network

    Daniela Dragoman

    2006-04-12

    We show that the quantum wavefunction, interpreted as the probability density of finding a single non-localized quantum particle, which evolves according to classical laws of motion, is an intermediate description of a material quantum particle between the quantum and classical realms. Accordingly, classical and quantum mechanics should not be treated separately, a unified description in terms of the Wigner distribution function being possible. Although defined on classical phase space coordinates, the Wigner distribution function accommodates the nonlocalization property of quantum systems, and leads to both the Schrodinger equation for the quantum wavefunction and to the definition of position and momentum operators.

  5. Dynamics and particle fluxes in atmospheric-pressure electronegative radio frequency microplasmas

    SciTech Connect

    McKay, K.; Iza, F.; Kong, M. G. [School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, LE11-3TU (United Kingdom); Liu, D. X.; Rong, M. Z. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049 (China)

    2011-08-29

    We report on intricate dynamics observed in atmospheric-pressure rf electronegative discharges where electrons and anions are separated due to their different mobilities. This results in the formation of positively charged regions between an electronegative plasma core and an oscillating electron ensemble. It is found that for a given input power, the electron, ion (both positive and negative) and neutral fluxes increase as the gap size is reduced, resulting in a more efficient delivery of chemical species to a treated target.

  6. Lidar studies of particles and temperatures of the atmosphere: First results from National Central University lidar

    Microsoft Academic Search

    J. B. Nee; G. B. Wang; P. C. Lee; S. B. Lin

    1995-01-01

    With a Rayleigh and Mie scattering lidar, installed rat the Central University in Chung-Li, Taiwan (25øN, 121øE), we studied the high clouds, aerosols, and temperatures of the atmosphere in the i5-60 km region since July, 1993. High clouds located near the tropopause were observed consistently. The clouds had stable structure and persisted for hours. One of the clouds presented had

  7. Lidar studies of particles and temperatures of the atmosphere: First results from National Central University lidar

    Microsoft Academic Search

    J. B. Nee; G. B. Wang; P. C. Lee; S. B. Lin

    1995-01-01

    With a Rayleigh and Mie scattering lidar, installed at the Central University in Chung-Li, Taiwan (25°N, 121°E), we studied the high clouds, aerosols, and temperatures of the atmosphere in the 15-60 km region since July, 1993. High clouds located near the tropopause were observed consistently. The clouds had stable structure and persisted for hours. One of the clouds presented had

  8. Strong atmospheric new particle formation in winter in urban Shanghai, China

    NASA Astrophysics Data System (ADS)

    Xiao, S.; Wang, M. Y.; Yao, L.; Kulmala, M.; Zhou, B.; Yang, X.; Chen, J. M.; Wang, D. F.; Fu, Q. Y.; Worsnop, D. R.; Wang, L.

    2015-02-01

    Particle size distributions in the range of 1.34-615 nm were recorded from 25 November 2013 to 25 January 2014 in urban Shanghai, using a combination of one nano condensation nucleus counter system, one nano scanning mobility particle sizer (SMPS), and one long-SMPS. Measurements of sulfur dioxide by an SO2 analyzer with pulsed UV fluorescence technique allowed calculation of sulfuric acid proxy. In addition, concentrations of ammonia were recorded with a differential optical absorption spectroscopy. During this 62-day campaign, 13 new particle formation (NPF) events were identified with strong bursts of sub-3 nm particles and subsequent fast growth of newly formed particles. The observed nucleation rate (J1.34), formation rate of 3 nm particles (J3), and condensation sink were 112.4-271.0 cm-3 s-1, 2.3-19.2 cm-3 s-1, and 0.030-0.10 s-1, respectively. Subsequent cluster/nanoparticle growth (GR) showed a clear size dependence, with average values of GR1.35~1.39, GR1.39~1.46, GR1.46~1.70, GR1.70~2.39, GR2.39~7, and GR7~20 being 1.6±1.0, 1.4±2.2, 7.2±7.1, 9.0±11.4, 10.9±9.8, and 11.4±9.7 nm h-1, respectively. Correlation between nucleation rate (J1.34) and sulfuric acid proxy indicates that nucleation rate J1.34 was proportional to a 0.65±0.28 power of sulfuric acid proxy, indicating that the nucleation of particles can be explained by the activation theory. Correlation between nucleation rate (J1.34) and gas-phase ammonia suggests that ammonia was associated with NPF events. The calculated sulfuric acid proxy was sufficient to explain the subsequent growth of 1.34-3 nm particles, but its contribution became smaller as the particle size grew. Qualitatively, NPF events in urban Shanghai likely occur on days with low levels of aerosol surface area, meaning the sulfuric acid proxy is only a valid predictor when aerosol surface area is low.

  9. A Method for Estimating the Bipolar Charge Distribution Variation on Aerosol Particles with Atmospheric Conditions

    NASA Astrophysics Data System (ADS)

    Leppä, J.; Gopalakrishnan, R.; Flagan, R. C.

    2014-12-01

    Many commonly used instruments that measure the aerosol particle number size distribution, such as Scanning Mobility Particle Sizer, are based on the following principle: The particle sample is brought to a steady-state charge distribution in a bipolar aerosol charger. The particles are then segregated according to their electrical mobilities using differential mobility analyzer, DMA. Finally, the concentration of the particles is measured using a condensation particle counter, CPC. To estimate the particle size distribution, the concentration data are then inverted using an algorithm that takes into account the steady-state charge distribution and the performance characteristics of the DMA and CPC. Considerable effort has gone into the characterization of the instruments used in these measurements. The charge distribution remains the greatest source of uncertainty in the mobility based size distribution measurements. The charge distribution depends, at least, on the properties of the ion and particle (radius, density, relative permittivity and number of charges), concentrations of negative and positive ions, temperature and pressure. With these values given, the collision frequencies of ions and particles can be modeled to determine the charge distribution, but that can be very time consuming. Instead, the charge distribution is usually estimated using a simple parameterization of the results of one such model. The collision process can, however, be described using only two dimensionless parameters, namely the diffusive Knudsen number, KnD, and the ratio of electric potential energy to thermal energy, ?E. A given pair of KnD and ?E may describe multiple collision conditions, but it defines a single value of dimensionless flux coefficient, H. This allows us to tabulate the values of KnD, ?E and H, so that H can be determined by interpolation for conditions corresponding to the measurements. The charge distribution can readily be calculated from the interpolated values of H. This procedure is particularly useful in the case of airborne measurements, since pressure and temperature variations with altitude result in a large deviations of the charge distribution from the commonly used parameterization.

  10. Measuring rates of reaction in supercooled organic particles with implications for atmospheric aerosol.

    PubMed

    Hearn, John D; Smith, Geoffrey D

    2005-07-01

    The kinetics of heterogeneous reactions involving supercooled organic droplets is reported for the first time. Reactions between ozone and internally-mixed sub-micrometre particles containing an unsaturated alkenoic acid, oleic acid, and an n-alkanoic acid, myristic acid, were studied as a simple model for the oxidation of meat-cooking aerosol. The reactions were followed by monitoring the rate of oleic acid loss using an Aerosol CIMS (chemical ionization mass spectrometry) instrument for real-time particle analysis. Evidence of as much as 32 degrees C supercooling at room temperature was observed depending on particle composition. FTIR spectra of the aerosol also demonstrate features indicative of supercooling. Particles in which crystallization was induced by cooling below room temperature demonstrated decreased reactivity by a factor of 12 compared to supercooled particles of the same composition. This drastic difference in reactivity could have significant implications for the lifetimes of reactive species in ambient aerosol as well as for the accurate source apportionment of particulate matter. PMID:16189562

  11. Determination of alkylamines in atmospheric aerosol particles: a comparison of gas chromatography-mass spectrometry and ion chromatography approaches

    NASA Astrophysics Data System (ADS)

    Huang, R.-J.; Li, W.-B.; Wang, Y.-R.; Wang, Q. Y.; Jia, W. T.; Ho, K.-F.; Cao, J. J.; Wang, G. H.; Chen, X.; Haddad, I. EI; Zhuang, Z. X.; Wang, X. R.; Prévôt, A. S. H.; O'Dowd, C. D.; Hoffmann, T.

    2014-07-01

    In recent years low molecular weight alkylamines have been recognized to play an important role in particle formation and growth in the lower atmosphere. However, major uncertainties are associated with their atmospheric processes, sources and sinks, mostly due to the lack of ambient measurements and the difficulties in accurate quantification of alkylamines at trace level. In this study, we present the evaluation and optimization of two analytical approaches, i.e., gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC), for the determination of alkylamines in aerosol particles. Alkylamines were converted to carbamates through derivatization with isobutyl chloroformate for GC-MS determination. A set of parameters affecting the analytical performances of the GC-MS approach, including reagent amount, reaction time and pH value, was evaluated and optimized. The accuracy is 84.3-99.1%, and the limits of detection obtained are 1.8-3.9 pg (or 0.02-0.04 ng m-3). For the IC approach, a solid-phase extraction (SPE) column was used to separate alkylamines from interfering cations before IC analysis. 1-2% (v/v) of acetone (or 2-4% (v/v) of acetonitrile) was added to the eluent to improve the separation of alkylamines on the IC column. The limits of detection obtained are 2.1-15.9 ng (or 0.9-6.4 ng m-3), and the accuracy is 55.1-103.4%. The lower accuracy can be attributed to evaporation losses of amines during the sample concentration procedure. Measurements of ambient aerosol particle samples collected in Hong Kong show that the GC-MS approach is superior to the IC approach for the quantification of primary and secondary alkylamines due to its lower detection limits and higher accuracy.

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

    PubMed

    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. PMID:25076527

  13. Particle size distribution of nitrate and sulfate in the marine atmosphere

    Microsoft Academic Search

    D. L. Savoie; J. M. Prospero

    1982-01-01

    Cascade impactor samples were collected at coastal sites on Sal Island, Barbados, and Virginia Key, Miami during 1974 and at two Miami coastal sites on Virginia Key and Key Biscayne during 1981. In all of the samples, the majority of the nitrate mass was found on intermediate size particles and exhibited a mass median diameter (MMD) of about 4 pm.

  14. The NOAA POES Satellite Detects Record Particle Flows into the Earths Upper Atmosphere

    NSDL National Science Digital Library

    Tom Bridgman

    2004-07-08

    This set of still images from the NOAA-POES satellite are derived from measurements by particle detectors in low Earth orbit. The data are sampled along the orbit track and then interpolated in time and position for the rest of the polar region. This interpolation is responsible for the curved block-shaped artifacts in the images.

  15. Parameterization of Cloud Optical Properties for a Mixture of Ice Particles for use in Atmospheric Models

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Lee, Kyu-Tae; Yang, Ping; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Based on the single-scattering optical properties that are pre-computed using an improve geometric optics method, the bulk mass absorption coefficient, single-scattering albedo, and asymmetry factor of ice particles have been parameterized as a function of the mean effective particle size of a mixture of ice habits. The parameterization has been applied to compute fluxes for sample clouds with various particle size distributions and assumed mixtures of particle habits. Compared to the parameterization for a single habit of hexagonal column, the solar heating of clouds computed with the parameterization for a mixture of habits is smaller due to a smaller cosingle-scattering albedo. Whereas the net downward fluxes at the TOA and surface are larger due to a larger asymmetry factor. The maximum difference in the cloud heating rate is approx. 0.2 C per day, which occurs in clouds with an optical thickness greater than 3 and the solar zenith angle less than 45 degrees. Flux difference is less than 10 W per square meters for the optical thickness ranging from 0.6 to 10 and the entire range of the solar zenith angle. The maximum flux difference is approximately 3%, which occurs around an optical thickness of 1 and at high solar zenith angles.

  16. Investigating a Liquid-Based Method for Online Organic Carbon Detection in Atmospheric Particles

    Microsoft Academic Search

    Richard E. Peltier; Rodney J. Weber; Amy P. Sullivan

    2007-01-01

    A Particle-Into-Liquid Sampler (PILS) was modified and coupled with a Total Organic Carbon (TOC) Analyzer (Sievers 800T, GE Water Systems, Boulder, CO), in an attempt to measure particulate organic carbon (OC) online. The PILS droplet collection system was changed from an inertial impactor to a miniature cyclone to increase the efficiency of transferring insoluble carbonaceous aerosol to the liquid sample

  17. Adhesion of finely dispersed particles to the surface of coating materials

    SciTech Connect

    Petryanov, I.V.; Lyashkevich, I.M.; Sadovskii, B.F.; Chernaya, L.G.; Chernyaeva, G.A.

    1986-12-01

    It was established experimentally that compressed gypsums with added organosilicon liquids GKZh-10 and GKZh-94 have the lowest values of the molecular and capillary components of adhesive strength of particles to surface. The specific bulk and surface electrical conductivities of natural marble are 3-4 orders of magnitude greater than those of the gypsums. Thus the high-strength gypsums with the special additives have significantly lower adhesive strength toward dust particles than does natural marble. The dependence of the adhesive properties of materials on surface structure was estimated by scanning electron microscopy. The dust-retentive capability of the sample surfaces was determined by blow-off of precipitated particles by a current of filtered air.

  18. Fabrication of superconducting metal-oxide textiles by heating impregnated polymeric material in a weakly oxidizing atmosphere

    SciTech Connect

    Van den Sype, J.S.

    1993-07-13

    A process is described for producing crystalline fibers, textiles or shapes comprised of YBa[sub 2]Cu[sub 3]O[sub 7[minus]x] where x varies from about 0 to about 0.4, said process comprising: (a) impregnating a preformed organic polymeric material with three metal compounds to provide metal elements in said material in substantially the atomic ratio occurring in said YBa[sub 2]Cu[sub 3]O[sub 7[minus]x]; (b) heating said impregnated material in a weakly oxidizing atmosphere containing from about 0.05% to about 2% oxygen by volume to a temperature sufficiently high to at least partially pyrolize and oxidize said organic material and at least partially oxidize said metal compounds substantially without ignition of said organic material and without formation of a molten phase or reaching a decomposition temperature of said YBa[sub 2]Cu[sub 3]O[sub 7[minus]x]; and (c) cooling the resulting material in at least a moderately oxidizing atmosphere to room temperature so as to obtain said fibers, textiles or shapes.

  19. Photocatalytic atrazine degradation by synthetic minerals, atmospheric aerosols, and soil particles.

    PubMed

    Lackhoff, Marion; Niessner, Reinhard

    2002-12-15

    In this work, the photocatalytic atrazine degradation by seven synthetic minerals and five environmental particle samples was examined to investigate a possible contribution of photocatalysis to the abiotic degradation of atrazine in the environment. Particle suspensions containing 500 ng/L atrazine were irradiated with a sun simulator, and the atrazine degradation was monitored by enzyme-linked immunosorbent assay (ELISA). Atrazine detection by ELISA proved to be an useful analytical tool because of low cross-reactivity of atrazine metabolites and high sensitivity with detection limits in the lower nanograms per liter range. The atrazine degradation followed first-order kinetics, and the obtained rate coefficients were compared with the rate of direct photolysis. Known photocatalysts, such as TiO2 and ZnO, showed the expected fast photocatalytic degradation (k = 27-327 x 10(-3) min(-1)) of atrazine. The degradation rates detected upon irradiation of titanium-, zinc-, or iron-containing minerals were orders of magnitudes lower (k = 0.15-0.70 x 10(-3) min(-1)) but still significantly faster than direct photolysis without particles (k = 0.10 x 10(-3) min(-1)). With environmental particle samples (soot, fly ash, sand, road dust, and volcanic ash), however, no significant photocatalytic activity was observed (k = 0.07-0.16 x 10(-3) min(-1)). The atrazine degradation rates were in the range of direct photolysis. Thus photocatalysis by aerosol or soil particles appears not to enhance abiotic atrazine degradation in the environment. PMID:12521159

  20. Porous Chromatographic Materials as Substrates for Preparing Synthetic Nuclear Explosion Debris Particles

    SciTech Connect

    Harvey, Scott D.; Liezers, Martin; Antolick, Kathryn C.; Garcia, Ben J.; Sweet, Lucas E.; Carman, April J.; Eiden, Gregory C.

    2013-06-13

    In this study, we investigated several porous chromatographic materials as synthetic substrates for preparing surrogate nuclear explosion debris particles. The resulting synthetic debris materials are of interest for use in developing analytical methods. Eighteen metals, including some of forensic interest, were loaded onto materials by immersing them in metal solutions (556 mg/L of each metal) to fill the pores, applying gentle heat (110°C) to drive off water, and then treating them at high temperatures (up to 800°C) in air to form less soluble metal species. High-boiling-point metals were uniformly loaded on spherical controlled-pore glass to emulate early fallout, whereas low-boiling-point metals were loaded on core-shell silica to represent coated particles formed later in the nuclear fallout-formation process. Analytical studies were applied to characterize solubility, material balance, and formation of recalcitrant species. Dissolution experiments indicated loading was 1.5 to 3 times higher than expected from the pore volume alone, a result attributed to surface coating. Analysis of load solutions before and after filling the material pores revealed that most metals were passively loaded; that is, solutions filled the pores without active metal discrimination. However, niobium and tin concentrations were lower in solutions after pore filling, and were found in elevated concentrations in the final products, indicating some metals were selectively loaded. High-temperature treatments caused reduced solubility of several metal species, and loss of some metals (rhenium and tellurium) because volatile species were formed. Sample preparation reproducibility was high (the inter-batch relative standard deviation was 7.8%, and the intra-batch relative standard deviation was 0.84%) indicating that this material is suitable for use as a working standard for analytical methods development. We anticipate future standardized radionuclide-loaded materials will find use in radioanalytical methods development and/or serve as a starting material for the synthesis of more complex forms of nuclear explosion debris (e.g., Trinitite).

  1. Material brittle fracture owing to thermoelastic effect of high energy nuclear particle

    SciTech Connect

    Kalinichenko, A.I. [Kharkiv State Univ. (Ukraine)

    1996-12-31

    Rapid arising of the overheated domain near very heavy ion path (near fast neutron collision point) in solid results in generation of cylinder (spherical) thermoelastic stress wave. The latter can exceed the material strength and cause brittle fracture at going out on the free body interface. Size and shape of an erosion zone as well as erosion rate for both sorts of primary nuclear particles are found. The role of wave attenuation is discussed. The products of erosion are of macroscopic scaly particles having the typical thickness (1 {divided_by} 5) {center_dot} 10{sup -7} cm and mass 10{sup -18} {divided_by} 10{sup -17} g. Such ion (neutron)-stimulated thermoacoustic grinding can take place in radioactive materials with fissionable addenda. The consideration of the brittle destruction under cosmic ray bombardment may be essential for equipment of deep space missions.

  2. Subscale Testing of Nozzle Ablative Materials in a Supersonic Particle Impingement Environment

    NASA Technical Reports Server (NTRS)

    Howse, S.; Lawrence, T.

    2004-01-01

    Recent efforts to evaluate materials to replace the current NARC rayon used in the nozzle ablative of the NASA's Reusable Solid Rocket Motor (SRM), several tests were developed to look at the performance of supersonic particle impact region of the aft exit cone. It was seen in early testing that some potential candidates did not perform as well as the current NARC based material and so the 24 inch Solid Rocket Motor (SRTM) exit cone design was extended and contoured to induce particle impingement in the aft end. The SRTM testing provided a larger testbed to evaluate the results seen in the Solid Fuel Supersonic Blast Tube. Testing was performed in each test bed on two variants of the final two candidate materials. The materials were a standard prewoven Lyocell, a postwoven Lyocell, an Enka rayon, and Enka rayon processed at a higher carbonization temperature. This paper presents the results of the four materials in the SSBT and the SRTM tests as compared against the NARC baseline. Erosion, char, and plylift results are discussed in detail.

  3. Hollow lithiated metal oxide particles as lithium-ion battery cathode materials

    Microsoft Academic Search

    Gary M. Koenig; Ilias Belharouak; Huiming M. Wu; Khalil Amine

    2011-01-01

    We report the synthesis and characterization of the hollow micrometer-sized (Mn0.5Ni0.4Co0.1)CO3 precursor, and one of its promising lithium-enriched phases. The chemical composition of the resulting lithiated final material was Li1.2(Mn0.5Ni0.4Co0.1)O2+y. Lithium half cells with cathodes comprised of these hollow particles as the active intercalation material showed a reversible capacity of 183mAh\\/g when cycled between 2.0V and 4.6V. X-ray diffraction patterns

  4. Biological aerosol particles in the atmosphere and their impact on clouds (BIOCLOUDS)

    NASA Astrophysics Data System (ADS)

    Amato, Pierre; Attard, Eleonore; Deguillaume, Laurent; Delort, Anne-Marie; Flossmann, Andrea; Good, Nicholas; Joly, Muriel; Koop, Thomas; Möhler, Ottmar; Monier, Marie; Morris, Cindy; Oehm, Caroline; Pöschl, Ulrich; Sancelme, Martine

    2015-04-01

    The project BIOCLOUDS aimed at investigating and quantifying the role of bioaerosols in tropospheric clouds. We focused on the studies on microorganisms, mainly bacteria. To reach our objective we (1) isolated and identified INA bacterial strains in cloud waters, (2) studied in more details IN properties of bacteria isolated from cloud waters in laboratories and cloud chamber, (3) used new data as input to cloud models. 1. Isolation and Identification of INA bacterial strains in cloud waters Cloud water samples were collected at the puy de Dôme station under sterile conditions, microorganisms were cultured on agar plates and further identified by DNA sequencing coding for16SrRNA. 257 bacterial strains isolated from 25 cloud events were screened and 44 isolates were selected as they belonged to Pseudomonas, Xanthomonas and Erwinia genera which are potential INA candidates. Using the classical "Droplet Freezing method" as ice nucleation test, 7 strains were shown INA+. Their cumulative IN frequency profiles were established and showed that some of them are very efficient, for example the strain Pseudomonas syringae 13b74 started to nucleate a t-3°C and 4% of the cells were active at- 5°C. 2. Further laboratory investigations of IN properties of cloud bacterial strains All the experiments presented in this section were carried out with 3 Pseudomonas syringae strains. We tested the influence of O3, NO, UV and pH, which are atmospheric markers of anthropogenic activity, on the IN activity of the Pseudomonas strains. It was clearly shown that pH had a main influence, acidic pHs decreased the IN activity of the strains. This suggests a negative impact of human emissions on the natural capacity of bacteria to precipitate with rain. The 3 Pseudomas strains were sprayed in the AIDA cloud chamber. The survival of these strains with time before cloud formation was measured and will be used in the future to parameterize models for bacterial transport. After cloud formation, IN activity of bacteria was followed with time, our results suggest that bacteria are precipitated in the cloud chamber as a result of their IN activity. Also the coating of bacteria with sulfates decreased their IN activity, pointing out the negative potential anthropogenic influence on IN bacteria activity. 3. Modeling study to see if any impact of bacteria on cloud development and/or precipitation is realistic. Modeling studies were performed with DESCAM (Detailed SCAvenging Model) using as an input the new data from the different campaigns in AIDA. M. VAÏTILINGOM et al. Atmospheric Environment, 2012, 56, 88-100. E. ATTARD et al. Atmospheric Chemistry and Physics, 2012, 12, 10667-10677. M. JOLY et al. Atmospheric Environment, 2013, 70, 392-400.

  5. Pd Particles as Standardized Test Material for Bioavailability Studies of Traffic Related Pd Emissions to Barley Plants

    Microsoft Academic Search

    Kerstin Leopold; Michael Schuster

    \\u000a Model palladium particles similar to those emitted from catalytic car exhaust converters were prepared and characterized with\\u000a the intention of providing standardized material for investigation of the chemical behaviour and bioavailability of traffic\\u000a related Pd emissions. Three types of Pd particles—Pd nanoparticles dispersed on silica support particles (Pd\\/SiO2), Pd only nanoparticles (Pd-NPs) and Pd micrometer particles (Pd-MPs)—were prepared and characterized

  6. New particle formation events arising from painting materials in an indoor microenvironment

    NASA Astrophysics Data System (ADS)

    Lazaridis, Mihalis; Serfozo, Norbert; Chatoutsidou, Sofia Eirini; Glytsos, Thodoros

    2015-02-01

    Particulate matter (PM) number size distribution and mass concentration along with total volatile organic compounds (TVOC) were measured during emissions from painting materials inside an indoor microenvironment. The emission sources were derived from oil painting medium and turpentine used for painting. Two sets of measurements (10 experiments) were conducted in a laboratory room of 54 m3. New particle formation events were observed in all 10 experiments. The nucleation events lasted on average less than one hour with an average growth rate 33.9 ± 9.1 nm/h and average formation rate 21.1 ± 8.7 cm-3s-1. After the end of the nucleation event, a condensational growth of indoor particles followed with average growth rate 11.6 ± 2.8 nm/h and duration between 1.4 and 4.1 h. High concentrations up to 3.24 ppm were measured for the indoor TVOC concentrations during the experiments. Simultaneous mass and number size concentration measurements were performed outdoors where no new particle formation event was observed. It is the first time that high nucleation rates indoors were observed in conjunction with high TVOC concentrations originating from painting materials which resulted to high exposure concentration levels of particle number concentration.

  7. The effects of particle-size distribution and chloride depletion of sea-salt aerosols on estimating atmospheric deposition at a coastal site

    Microsoft Academic Search

    M. J. Ten Harkel

    1997-01-01

    Estimating atmospheric deposition in a coastal region cannot be done without taking care of the size distribution and amount of chloride depletion of sea-salt aerosols.Size distribution of the dry deposition particles is important when the approach of Ulrich (1983, Effects of Accumulation of Air Pollutants in Forest Ecosystems, pp. 33–45. Reidel, Dordrecht) is used to estimate total atmospheric deposition levels

  8. The influence of formation material properties on the response of water levels in wells to Earth tides and atmospheric loading

    USGS Publications Warehouse

    Rojstaczer, S.; Agnew, D.C.

    1989-01-01

    The water level in an open well can change in response to deformation of the surrounding material, either because of applied strains (tidal or tectonic) or surface loading by atmospheric pressure changes. Under conditions of no vertical fluid flow and negligible well bore storage (static-confined conditions), the sensitivities to these effects depend on the elastic properties and porosity which characterize the surrounding medium. The hydraulic diffusivity which governs pressure diffusion in response to surface loading is slightly smaller than that which governs fluid flow in response to applied strain. Analysis of the static-confined response of five wells to atmospheric loading and Earth tides gives generally reasonable estimates for material properties. -from Authors

  9. Relevance of Sb(III), Sb(V), and Sb-containing nano-particles in urban atmospheric particulate matter.

    PubMed

    Canepari, Silvia; Marconi, Elisabetta; Astolfi, Maria Luisa; Perrino, Cinzia

    2010-07-01

    A quick and reliable analytical method for the separation and quantification of extractable Sb(III) and Sb(V) in atmospheric particulate matter (PM) by ion chromatography(IC)-inductively coupled plasma-mass spectrometry (ICP-MS) has been optimized, validated on pairs of real, equivalent PM(10) samples and applied to a field monitoring campaign in a urban site. Both Sb(III) and Sb(V) forms were detected in real samples with Sb(III)/Sb(V) ratios up to 1.5. These two Sb species accounts only for a portion, of variable magnitude, of the total extractable Sb (10-70%); anyway, no other soluble Sb species were detected in the samples. The analysis of size-segregated samples collected by a 13-stage impactor showed that the recovery of [Sb(III) + Sb(V)] versus total extractable Sb is almost quantitative in the coarse fraction while it is below than 10% in the fine fraction. In the extracted solution from particles below 1 mum we could highlight the presence of Sb-containing suspended solid nano-particles, which probably constitute the missing fraction. The contribution of nano-particles can be estimated as the difference between ICP-MS and IC-ICP-MS data, as small size solid bodies are able to pass through the nebulizer and reach the plasma torch, while they are retained by the chromatographic column. The aggregation state of these nano-particles seems to be easily altered when they are suspended in a water solution; a similar behavior could be hypothesized when in contact with biological fluids. It has been confirmed that brake pad abrasion is the prevalent source of Sb(III) in PM and that Sb(V) may be formed by oxidation during the braking processes. Differing from other environmental matrices, there is no evidence of any spontaneous oxidative conversion within the two species. PMID:20496054

  10. ATMOSPHERIC OCCURRENCE OF 2-NITROBENZANTHRONE ASSOCIATED WITH AIRBORNE PARTICLES IN CENTRAL TOKYO

    Microsoft Academic Search

    Koji Inazu; Vu Duc Nam; Takahiro Asato; Hiroshi Okochi; Yoshiharu Hisamatsu; Takaaki Kobayashi; Toshihide Baba

    2008-01-01

    2- and 3-Nitrobenzanthrones (NBAs) in airborne particles collected in central Tokyo on a seasonal basis from 1996 to 2001 are quantified and possible sources are investigated. The concentrations of 2- and 3-NBA are found to range from 49 to 831 fmol mand 0.5 to 3.5 fmol m, while the nitrated polycyclic hydrocarbons 1-nitropyrene and 2-nitrofluoranthene are found at concentrations of

  11. The inportance of organic and elemental carbon in the fine atmospheric aerosol particles

    Microsoft Academic Search

    A. Molnár; E. Mészáros; H. C. Hansson; H. Karlsson; A. Gelencsér; G. Y. Kiss; Z. Krivácsy

    1999-01-01

    During a field campaign the chemical character of fine (d<2.5?m) aerosol particles was studied at K-puszta, Hungary within the framework of a project of the European Union. The organic and elemental carbon fraction, as well as the concentration of major inorganic constituents with respect to the total fine aerosol mass are presented in this paper. It was found that organic

  12. Study of particle rebound characteristics and material erosion at high temperature

    SciTech Connect

    Tabakoff, W.; Hamed, A.; Metwally, A.; Yeuan, J.; Pasin, M. (Cincinnati Univ., OH (USA). Dept. of Aerospace Engineering and Engineering Mechanics)

    1990-10-01

    An experimental investigation was conducted to study the ash particle rebound characteristics and the associated erosion behavior of superalloys and aluminide coatings subjected to gas-particle flows at elevated temperatures. At three-component LDV system was used to measure the restitution parameters of 15 micron mean diameter coal ash particles impacting some widely used superalloys and coatings at different angles. Results show the variation restitution ratios with the impingement angle for the coated and uncoated superalloys. Experimental results were used to develop correlations for the restitution parameters for coated and uncoated superalloys. A theoretical model based on elastic-plastic theory has been developed to simulate single solid particle impacts on solid targets. The erosion behaviors of many superalloys and protective coatings have also been investigated experimentally at high temperatures using a specially designed erosion tunnel. Also, the cumulative effect of the impacting particle mass on the weight loss and erosion rate were investigated. Semi-empirical erosion equations were developed for these materials based on the experimental erosion data and correlations of the restitution parameters. Coatings tested include: platinum alimunides, cobalt aluminides, nickel aluminides, rhodium platinum aluminides, and chromium carbide. Superalloys tested were nickel base alloys Inco in-738 and Mar-M246, as well as Cobalt base alloys X40 and FSX-414. 10 refs., 86 figs., 5 tabs.

  13. Particle-Phase Chemistry of Secondary Organic Material: Modeled Compared to Measured O:C and H:C Elemental Ratios Provide Constraints

    SciTech Connect

    Chen, Qi; Liu, Yingjun; Donahue, N. M.; Shilling, John E.; Martin, Scot T.

    2011-05-11

    Chemical mechanisms for the production of secondary organic material (SOM) are developed in focused laboratory studies but widely used in the complex modeling context of the atmosphere. Given this extrapolation, a stringent testing of the mechanisms is important. In addition to particle mass yield as a typical standard for model-measurement comparison, particle composition expressed as O:C and H:C elemental ratios can serve as a higher dimensional constraint. A paradigm for doing so is developed herein for SOM production from a C5 C10 C15 terpene sequence, namely isoprene, R-pinene, and ?-caryopyhllene. The model MCM-SIMPOL is introduced based on the Master Chemical Mechanism (MCM v3.2) and a group contribution method for vapor pressures (SIMPOL). The O:C and H:C ratios of the SOM are measured using an Aerosol Mass Spectrometer (AMS). Detailed SOM-specific AMS calibrations for the organic contribution to the H2Oþ and COþ ions indicate that published O:C and H:C ratios for SOM are systematically too low. Overall, the measurement-model gap was small for particle mass yield but significant for particle-average elemental composition. The implication is that a key chemical pathway is missing from the chemical mechanism. The data can be explained by the particle-phase homolytic decomposition of organic hydroperoxides and subsequent alkyl-radical-promoted oligomerization.

  14. Preparation of spherical particles by laser melting in liquid using TiN as a raw material

    NASA Astrophysics Data System (ADS)

    Kawasoe, Kosuke; Ishikawa, Yoshie; Koshizaki, Naoto; Yano, Tetsuji; Odawara, Osamu; Wada, Hiroyuki

    2015-04-01

    Submicron spherical particles comprising TiN, TiO2, and TiOxNy were prepared by nanosecond pulsed laser irradiation of TiN colloidal nanoparticles. A second harmonic generation Nd:YAG laser (wavelength: 532 nm) was used. We investigated how laser fluence, irradiation time, and raw material concentration affected spherical particle diameters and compositions. Laser irradiation of about 80 mJ/cm2 was required to obtain spherical particles. When laser fluence was increased to more than 350 mJ/cm2, spherical particles disappeared and nanoparticles formed. In the fluence range in which spheronization occurred, particle sizes increased with the laser fluence. XRD spectra showed that the oxidation of particles occurred during melting. From EDS mapping and XPS spectra, oxidization was clearly visible on particle surfaces, and the presence of TiOxNy and TiO2 was confirmed. Irradiation time and raw material concentration had little effect on product grain size.

  15. Particle characteristics of different materials after ultra-short pulsed laser (USPL) irradiation

    NASA Astrophysics Data System (ADS)

    Meister, Joerg; Schelle, Florian; Kowalczyk, Philip; Frentzen, Matthias

    2012-01-01

    The exposition of nanoparticles caused by laser application in dental health care is an open discussion. Based on the fact that nanoparticles can penetrate through the mucosa, the knowledge about particle characteristics after irradiation with an USPL is of high importance. Therefore, the aim of this study was to investigate the particle characteristics, especially the size of the ablated debris after USPL irradiation. The irradiation was carried out with an USP Nd:YVO4 laser with a center wavelength of 1064 nm. Based on the pulse duration of 8 ps and a pulse repetition rate of 500 kHz the laser emits an average power of 9 W. The materials investigated were dental tissues and dental restorative materials (composite and amalgam), ceramic and different metals (gold and aluminium). The samples were irradiated with a power density in the order of 300 GW/cm2 at distances of 5, 10, 15, and 20 mm. The debris was collected on an object plate. SEM pictures were used for analysis of the ablation debris. Depending on the irradiated material, we observed different kinds of structures: vitreous, flocculent, and pellet-like. The mean particle sizes were 10 x 10 up to 30 x 30 ?m2. In addition, a cluster of ablated matter (nanometer range) distributed over the whole irradiated area was found. With increasing distances the cluster structure reduced from multi-layer to mono-layer clusters. Particle sizes in the micrometer and nanometer range were found after irradiation with an USPL. The nanoparticles create a cluster structure which is influenced by increasing distances.

  16. Rice straw-wood particle composite for sound absorbing wooden construction materials.

    PubMed

    Yang, Han-Seung; Kim, Dae-Jun; Kim, Hyun-Joong

    2003-01-01

    In this study, rice straw-wood particle composite boards were manufactured as insulation boards using the method used in the wood-based panel industry. The raw material, rice straw, was chosen because of its availability. The manufacturing parameters were: a specific gravity of 0.4, 0.6, and 0.8, and a rice straw content (10/90, 20/80, and 30/70 weight of rice straw/wood particle) of 10, 20, and 30 wt.%. A commercial urea-formaldehyde adhesive was used as the composite binder, to achieve 140-290 psi of bending modulus of rupture (MOR) with 0.4 specific gravity, 700-900 psi of bending MOR with 0.6 specific gravity, and 1400-2900 psi of bending MOR with a 0.8 specific gravity. All of the composite boards were superior to insulation board in strength. Width and length of the rice straw particle did not affect the bending MOR. The composite boards made from a random cutting of rice straw and wood particles were the best and recommended for manufacturing processes. Sound absorption coefficients of the 0.4 and 0.6 specific gravity boards were higher than the other wood-based materials. The recommended properties of the rice straw-wood particle composite boards are described, to absorb noises, preserve the temperature of indoor living spaces, and to be able to partially or completely substitute for wood particleboard and insulation board in wooden constructions. PMID:12653275

  17. Nano-magnetic particles used in biomedicine: core and coating materials.

    PubMed

    Karimi, Z; Karimi, L; Shokrollahi, H

    2013-07-01

    Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine. PMID:23623057

  18. Effect of nano-silver particles in bonding material on field emission properties for carbon nanotube cathodes

    Microsoft Academic Search

    Young-Je An; Won-Sub Chung; Jiho Chang; Hong Chan Lee; Young-Rae Cho

    2008-01-01

    Effects of bonding materials in a screen-printing paste on field emission properties were investigated for carbon nanotube (CNT) cathodes. The CNT cathodes were characterized for their dependence on current density in terms of the sintering behavior of the bonding material. As the diameter of the Ag particles in the bonding material decreased from 1000 nm to 10 nm, the current density of

  19. Measuring and modeling the hygroscopic growth of two humic substances in mixed aerosol particles of atmospheric relevance

    NASA Astrophysics Data System (ADS)

    Zamora, I. R.; Jacobson, M. Z.

    2013-01-01

    The hygroscopic growth of atmospheric particles affects atmospheric chemistry and Earth's climate. Water-soluble organic carbon (WSOC) constitutes a significant fraction of the dry submicron mass of atmospheric aerosols, thus affecting their water uptake properties. Although the WSOC fraction is comprised of many compounds, a set of model substances can be used to describe its behavior. For this study, mixtures of Nordic Aquatic fulvic acid reference (NAFA) and Fluka humic acid (HA), with various combinations of inorganic salts (sodium chloride and ammonium sulfate) and other representative organic compounds (levoglucosan and succinic acid), were studied. We measured the equilibrium water vapor pressure over bulk solutions of these mixtures as a function of temperature and solute concentration. New water activity (aw) parameterizations and hygroscopic growth curves at 25 °C were calculated from these data for particles of equivalent composition. We examined the effect of temperature on the water activity and found a maximum variation of 9% in the 0-30 °C range, and 2% in the 20-30 °C range. Five two-component mixtures were studied to understand the effect of adding a humic substance (HS), such as NAFA and HA, to an inorganic salt or a saccharide. The deliquescence point at 25 °C for HS-inorganic mixtures did not change significantly from that of the pure inorganic species. However, the hygroscopic growth of HA-inorganic mixtures was lower than that exhibited by the pure salt, in proportion to the added mass of HA. The addition of NAFA to a highly soluble solute (ammonium sulfate, sodium chloride or levoglucosan) in water had the same effect as the addition of HA to the inorganic species for most of the aw range studied. Yet, the water uptake of these NAFA mixtures transitioned to match the growth of the pure salt or saccharide at high aw values. The remaining four mixtures were based on chemical composition data for different aerosol types. As expected, the two solutions representing organic aerosols (40% HS/40% succinic acid/20% levoglucosan) showed lower water uptake than the two solutions representing biomass burning aerosols (25% HS/27% succinic acid/18% levoglucosan/30% ammonium sulfate). However, interactions in multicomponent solutions may be responsible for the differences that arise in relative hygroscopic growth above RH of 95% when comparing three different HS in these two mixtures. The ZSR model was able to predict reasonably well the hygroscopic growth of all the mixtures below aw = 0.95, but produced large deviations for some multicomponent mixtures at higher values.

  20. Measuring and modeling the hygroscopic growth of two humic substances in mixed aerosol particles of atmospheric relevance

    NASA Astrophysics Data System (ADS)

    Zamora, I. R.; Jacobson, M. Z.

    2013-09-01

    The hygroscopic growth of atmospheric particles affects atmospheric chemistry and Earth's climate. Water-soluble organic carbon (WSOC) constitutes a significant fraction of the dry submicron mass of atmospheric aerosols, thus affecting their water uptake properties. Although the WSOC fraction is comprised of many compounds, a set of model substances can be used to describe its behavior. For this study, mixtures of Nordic aquatic fulvic acid reference (NAFA) and Fluka humic acid (HA), with various combinations of inorganic salts (sodium chloride and ammonium sulfate) and other representative organic compounds (levoglucosan and succinic acid), were studied. We measured the equilibrium water vapor pressure over bulk solutions of these mixtures as a function of temperature and solute concentration. New water activity (aw) parameterizations and hygroscopic growth curves at 25 °C were calculated from these data for particles of equivalent composition. We examined the effect of temperature on the water activity and found a maximum variation of 9% in the 0-30 °C range, and 2% in the 20-30 °C range. Five two-component mixtures were studied to understand the effect of adding a humic substance (HS), such as NAFA and HA, to an inorganic salt or a saccharide. The deliquescence point at 25 °C for HS-inorganic mixtures did not change significantly from that of the pure inorganic species. However, the hygroscopic growth of HA / inorganic mixtures was lower than that exhibited by the pure salt, in proportion to the added mass of HA. The addition of NAFA to a highly soluble solute (ammonium sulfate, sodium chloride or levoglucosan) in water had the same effect as the addition of HA to the inorganic species for most of the water activity range studied. Yet, the water uptake of these NAFA mixtures transitioned to match the growth of the pure salt or saccharide at high aw values. The remaining four mixtures were based on chemical composition data for different aerosol types. As expected, the two solutions representing organic aerosols (40% HS/40% succinic acid/20% levoglucosan) showed lower water uptake than the two solutions representing biomass burning aerosols (25% HS/27% succinic acid/18% levoglucosan/30% ammonium sulfate). However, interactions in multicomponent solutions may be responsible for the large variation of the relative water uptake of identical mixtures containing different HSs above a water activity of 0.95. The ZSR (Zdanovskii, Stokes, and Robinson) model was able to predict reasonably well the hygroscopic growth of all the mixtures below aw = 0.95, but produced large deviations for some multicomponent mixtures at higher values.

  1. Behavior of the unsteady jet of a mixture of a pressurized gas and dispersed particles discharged from a circular duct into the atmosphere

    Microsoft Academic Search

    D. V. Sadin

    1999-01-01

    The unsteady axisymmetric jet produced by discharge of a mixture of a pressurized gas and dispersed particles from a circular\\u000a duct into the atmosphere is studied within the framework of two-velocity, two-temperature gas dynamics. An attempt is undertaken\\u000a to allow for the effective pressure due to random particle motion. The collision mechanism is found to be essential to radial\\u000a expansion

  2. Parameterization for Atmospheric New-Particle Formation: Application to a System Involving Sulfuric Acid and Condensable Water-Soluble Organic Vapors

    Microsoft Academic Search

    Veli-Matti Kerminen; Tatu Anttila; Kari Lehtinen; Markku Kulmala

    2004-01-01

    A new parameterization for atmospheric new-particle formation has been developed. The parameterization takes into account the early growth of nucleated clusters by condensation of sulfuric acid and water-soluble organic vapors, as well as the scavenging of the growing nuclei by coagulation into larger pre-existing particles. The main input parameters are the nucleation rate, the concentration of sulfuric acid and organic

  3. Observations of the UARS Particle Environment Monitor and computation of ionization rates in the middle and upper atmosphere during a geomagnetic storm

    NASA Technical Reports Server (NTRS)

    Sharber, J. R.; Frahm, R. A.; Winningham, J. D.; Biard, J. C.; Lummerzheim, D.; Rees, M. H.; Chenette, D. L.; Gaines, E. E.; Nightingale, R. W.; Imhof, W. L.

    1993-01-01

    In this paper we present observations made by the Particle Environment Monitor (PEM) instruments during the geomagnetic storm of 8-9 November, 1991. Ionization and energy deposition rates as functions of altitude in the middle and upper atmosphere by incident electrons and positive ions in the storm interval are computed. The suite of PEM instruments provides a systematic measurement of energetic particles and their associated X-rays over an energy range not fully covered by previous satellite missions.

  4. Nanocrystalline materials for the dosimetry of heavy charged particles: A review

    NASA Astrophysics Data System (ADS)

    Salah, Numan

    2011-01-01

    Thermally stimulated luminescence or better known as thermoluminescence (TL) is a powerful technique extensively used for dosimetry of ionizing radiations. TL dosimeter (TLD) materials presently in use are inorganic crystalline materials. They are in the form of chips, single crystals or microcrystalline size powder. The most popular are LiF:Mg,Ti, LiF:Mg,Cu,P, CaSO 4:Dy, CaF 2:Dy and Al 2O 3:C. However, these TLD materials are not capable of precisely detecting heavy charged particles (HCP) irradiations in their present forms. The saturation effect is the major problem, which occurs at relatively low fluences (doses). Moreover, there is a significant variation in the TL glow curves structure with increase in doses, which is undesirable for the use in dosimetry. However, with the use of very tiny particles such as nanoscale TLD materials, this problem is overcome to a major extent. The TL results of the recently reported nanomaterials have revealed very imperative characteristics such as high sensitivity and saturation at very high doses. Recent studies on different luminescent nanomaterials showed that they have a potential application in dosimetry of heavy charged particles using TL technique, where the conventional microcrystalline phosphors saturate. This paper is a review on the prepared TLD nanomaterials, studied for their TL response to HCP. These are CaSO 4:Dy, LiF:Mg,Cu,P, K 2Ca 2(SO 4) 3:Eu and Ba 0.97Ca 0.03SO 4:Eu nanomaterials. The important results obtained in these nanomaterials and the possibility of using them as HCP dosimeters are discussed.

  5. Analysis of atmospheric aerosols by particle-induced X-ray emission, instrumental neutron activation analysis, and ion chromatography

    NASA Astrophysics Data System (ADS)

    Maenhaut, Willy; Raes, Nico; Wang, Wan

    2011-11-01

    Particle-induced X-ray emission (PIXE), ion chromatography (IC), and occasionally also instrumental neutron activation analysis (INAA) were used in combination for the analysis of atmospheric aerosol samples that were collected on Nuclepore polycarbonate filters. A comparison of the results enabled us to evaluate the matrix effects (i.e., particle size effects) of the PIXE analysis for the light elements and to assess the water-solubility and/or speciation of a number of elements (e.g., S, K, Ca). Results are presented from several measurement campaigns at urban and forested sites in Europe, whereby PM10 or PM2.5 filter samples were taken. From the PIXE and IC results for a 2003 summer campaign at the K-puszta site in Hungary, it was estimated that organosulphates could be responsible for 20% of the total sulphur concentration and 30% of the organic aerosol in PM10. The comparison of the IC and PIXE data for K and Ca from the various sites indicated that most of the Ca was water-soluble (the mineral dust Ca was presumably mostly present as calcite, and perhaps also in part as gypsum); in contrast, for K, only half of it was typically water-soluble, indicating that it was to a large extent associated with insoluble mineral dust. Exceptions, with almost fully water-soluble K, were found for samples that were substantially impacted by biomass burning.

  6. Particle-Support Interferences in Small-Angle X-Ray Scattering from Supported-Catalyst Materials

    NASA Astrophysics Data System (ADS)

    Binninger, Tobias; Garganourakis, Marios; Han, Jun; Patru, Alexandra; Fabbri, Emiliana; Sereda, Olha; Kötz, Rüdiger; Menzel, Andreas; Schmidt, Thomas J.

    2015-02-01

    Small-angle x-ray scattering (SAXS) is a powerful technique for the investigation of catalyst materials at the nanoscale. We present results of an anomalous SAXS study on metal-oxide-supported platinum particles used as electrocatalysts for oxygen reduction. The scattering interferences between catalyst particles and support material are taken into account qualitatively and quantitatively by a mathematical model for the data-fitting procedure. Our results clearly demonstrate the fundamental importance of these catalyst-particle-support-material interferences in the analysis of SAXS data from supported catalysts.

  7. Characteristics of atmospheric ice nucleating particles associated with biomass burning in the US: Prescribed burns and wildfires

    NASA Astrophysics Data System (ADS)

    McCluskey, Christina S.

    Insufficient knowledge regarding the sources and number concentrations of atmospheric ice nucleating particles (INP) leads to large uncertainties in understanding the interaction of aerosols with cloud processes, such as cloud life time and precipitation rates. This study utilizes measurements of INP from a diverse set of biomass burning events to better understand INP associated with biomass burning in the U.S. Prescribed burns in Georgia and Colorado, two Colorado wildfires and two laboratory burns were monitored for INP number concentrations. The relationship between nINP and total particle number concentrations, evident within prescribed burning plumes, was degraded within aged smoke plumes from the wildfires, limiting the utility of this relationship for comparing laboratory and field data. Larger particles, represented by n500nm, are less vulnerable to plume processing and have previously been evaluated for their relation to nINP. Our measurements indicated that for a given n500nm, nINP associated with the wildfires were nearly an order of magnitude higher than nINP found in prescribed fire emissions. Reasons for the differences between INP characteristics in these emissions were explored, including variations in combustion efficiency, fuel type, transport time and environmental conditions. Combustion efficiency and fuel type were eliminated as controlling factors by comparing samples with contrasting combustion efficiencies and fuel types. Transport time was eliminated because the expected impact would be to reduce n500nm, thus resulting in the opposite effect from the observed change. Bulk aerosol chemical composition analyses support the potential role of elevated soil dust particle concentrations during the fires, contributing to the population of INP, but the bulk analyses do not target INP composition directly. It is hypothesized that both hardwood burning and soil lofting are responsible for the elevated production of INP in the Colorado wildfires in addition to LRT of mineral dust. The chemical compositions of INP were probed directly via TEM imaging. Single particle analyses of residual INP showed that they comprised various C-containing particle types, but with a higher abundance of mineral and metal oxide containing INP in emissions from flaming phase combustion. Fractal soot was found as an INP type comprising up to 60% of collected INP in young smoke emissions from the Georgia prescribed burns. In a series of laboratory combustion experiments, the use of a new instrumental set up, pairing the CFDC with a single particle soot photometer, revealed up to a 60% decrease in active INP after the removal of refractory black carbon from smoke aerosol emitted from a highly flaming burn of wiregrass, supporting that soot particles serve as INP in fire emissions. The presence of soil minerals was clearly evident in TEM images of samples taken during the wildfires in addition to tarballs, carbon balls most commonly associated with aged smoke plumes. These results demonstrate that the ice nucleating particles observed in the wildfires were influenced by other factors not represented in the smoke emitted from the laboratory or prescribed burns. Finally, an INP parameterization was developed based on the temperature dependent relationship between nINP and n500nm, following methods used by previous studies. This parameterization is likely only representative of the Hewlett and High Park wildfires due to the apparent impact of non-biomass-burning aerosol. However, all wildfires are typically associated with vigorous localized convection and arid soils, required for the lofting of the soils and dusts similar to these wildfires. It will be useful to compare future wildfires in various regions to the proposed parameterization. (Abstract shortened by UMI.)

  8. Gas/particle distribution of polycyclic aromatic hydrocarbons in coupled outdoor/indoor atmospheres

    NASA Astrophysics Data System (ADS)

    Naumova, Yelena Y.; Offenberg, John H.; Eisenreich, Steven J.; Meng, Qingyu; Polidori, Andrea; Turpin, Barbara J.; Weisel, Clifford P.; Morandi, Maria T.; Colome, Steven D.; Stock, Thomas H.; Winer, Arthur M.; Alimokhtari, Shahnaz; Kwon, Jaymin; Maberti, Silvia; Shendell, Derek; Jones, Jennifer; Farrar, Corice

    Concentrations of polycyclic aromatic hydrocarbons (PAHs), PM 2.5, and organic and elemental carbon (OC and EC) were measured in 48 h integrated samples collected in the indoor and outdoor air in Los Angeles, CA, Houston, TX, and Elizabeth, NJ from July 1999 to June 2000. The objective of the study was to evaluate the hypothesis that outdoor air pollution contributed strongly to indoor air pollution. The measured partition coefficients of PAHs, Kp,meas, in the individual samples were well correlated with the compounds' sub-cooled liquid vapor pressure, pLo. Values of Kp,meas varied by about two orders of magnitude for any given value of vapor pressure. These variations in gas/particle partitioning of PAHs were higher than the estimated systematic and random error of Kp,meas and are related to the aerosol characteristics and sampling conditions. Stepwise multiple linear regression analysis (MLR) of the pooled data, which included pLo at 25°C, temperature, fOC and fEC as independent variables, explains 84.5% of the variability of the partition coefficients. This is higher than the explained variance when pLo is used as a single parameter (77.5%). The relative importance of each variable for prediction of PAH partition coefficient is determined by partial coefficients of determination. Vapor pressure at 25°C ( RpoL2=0.84) and temperature ( RT2=0.21) are the two most important predictors followed by fEC ( RfEC2=0.12) and fOC ( RfOC2=0.038). Both EC and OC carbon are important predictors of gas/particle partitioning of PAHs, with EC being a better predictor. Because EC is highly correlated with (and is a good tracer of) primary combustion-generated OC, this result suggests that PAHs more readily sorb on combustion-generated aerosol containing EC. Enrichment of the indoor aerosol in non-combustion OC suggests that sorption of PAHs is more important in the indoor air compared to the outdoor air. The MLR developed in this work will improve prediction of gas/particle partitioning of PAHs in indoor and outdoor air.

  9. Airborne instruments to measure atmospheric aerosol particles, clouds and radiation: A cook's tour of mature and emerging technology

    NASA Astrophysics Data System (ADS)

    Baumgardner, D.; Brenguier, J. L.; Bucholtz, A.; Coe, H.; DeMott, P.; Garrett, T. J.; Gayet, J. F.; Hermann, M.; Heymsfield, A.; Korolev, A.; Krämer, M.; Petzold, A.; Strapp, W.; Pilewskie, P.; Taylor, J.; Twohy, C.; Wendisch, M.; Bachalo, W.; Chuang, P.

    2011-10-01

    An overview is presented of airborne systems for in situ measurements of aerosol particles, clouds and radiation that are currently in use on research aircraft around the world. Description of the technology is at a level sufficient for introducing the basic principles of operation and an extensive list of references for further reading is given. A number of newer instruments that implement emerging technology are described and the review concludes with a description of some of the most important measurement challenges that remain. This overview is a synthesis of material from a reference book that is currently in preparation and that will be published in 2012 by Wiley.

  10. Solar cycle dynamics of solar, magnetospheric, and heliospheric particles, and long-term atmospheric coupling: SAMPLEX

    NASA Technical Reports Server (NTRS)

    Mason, G. M. (Principal Investigator); Hamilton, D. C.; Blake, J. B.; Mewaldt, R. A.; Stone, E. C.; Baker, D. N.; VonRosenvinge, T. T.; Callis, L. B.; Klecker, B.; Hovestadt, D.; Scholer, M.

    1996-01-01

    This report summarizes science analysis activities by the SAMPEX mission science team during the period during the period July 1, 1995 through July 1, 1996. Bibliographic entries for 1995 and 1996 to date (July 1996) are included. The SAMPEX science team was extremely active, with 20 articles published or submitted to refereed journals, 18 papers published in their entirety in Conference Proceedings, and 53 contributed papers, seminars, and miscellaneous presentations. The bibliography at the end of this report constitutes the primary description of the research activity. Science highlights are given under the major activity headings of anomalous cosmic rays, solar energetic particles, magnetospheric precipitating electrons, trapped H and He isotopes, and data analysis activities.

  11. Atmospheric emissions of elements or particles from the parkway sewage-sludge incinerator

    SciTech Connect

    Greenberg, R.R.; Zoller, W.H.; Gorden, G.E.

    1981-01-01

    Concentrations of about 30 elements were measured in dry sludge, fly ash, and suspended particulate matter from the stack of a fluidized-bed sewage incinerator equipped with a Centuri scrubber, a secondary scrubber, a gas cooler, and a demister. Although there is some enrichment of volatile elements on the suspended particles with respect to the sludge, the particulate emissions of elements observed in this study are quite small compared with other sources, e.g., the following: Pb, 2g/day; Cd, 0.17 g/day; Se 0.1 g/day; and Sb, 0.028 g/day from a sludge reactor burning approximately 600 kg of sludge per hour. Based on previous work the most significant of the toxic elements measured from this source is Hg vapor at a rate of approximately 50 g/day.

  12. The preparation of copper fine particle paste and its application as the inner electrode material of a multilayered ceramic capacitor

    NASA Astrophysics Data System (ADS)

    Yonezawa, Tetsu; Takeoka, Shinsuke; Kishi, Hiroshi; Ida, Kiyonobu; Tomonari, Masanori

    2008-04-01

    Well size-controlled copper fine particles (diameter: 100-300 nm) were used as the inner electrode material of multilayered ceramic capacitors (MLCCs). The particles were dispersed in terpineol to form a printing paste with 50 wt% copper particles. The MLCC precursor modules prepared by the layer-by-layer printing of copper and BaTiO3 particles were cosintered. Detailed observation of the particles, paste, and MLCCs before and after sintering was carried out by electron microscopy. The sintering temperature of Cu-MLCC was as low as 960 °C. The permittivity of these MLCCs was successfully measured with the copper inner layers.

  13. CPIC: A Curvilinear Particle-in-Cell Code for Plasma-Material Interaction Studies

    NASA Astrophysics Data System (ADS)

    Delzanno, Gian Luca; Camporeale, Enrico; Moulton, J. David; Borovsky, Joseph E.; MacDonald, Elizabeth A.; Thomsen, Michelle F.

    2013-12-01

    We describe a new electrostatic Particle-In-Cell (PIC) code in curvilinear geometry called Curvilinear PIC (CPIC). The code models the microscopic (kinetic) evolution of a plasma with the PIC method, coupled with an adaptive computational grid that can conform to arbitrarily shaped domains. CPIC is particularly suited for multiscale problems associated with the interaction of complex objects with plasmas. A map is introduced between the physical space and the logical space, where the grid is uniform and Cartesian. In CPIC, most operations are performed in logical space. CPIC was designed following criteria of versatility, robustness and performance. Its main features are the use of structured meshes, a scalable field solver based on the black box multigrid algorithm and a hybrid mover, where particles' position is in logical space while the velocity is in physical space. Test examples involving the interaction of a plasma with material boundaries are presented.

  14. CPIC: a Curvilinear Particle-In-Cell code for plasma-material interaction studies

    E-print Network

    Delzanno, Gian Luca; Moulton, J David; Borovsky, Joseph E; MacDonald, Elizabeth A; Thomsen, Michelle F

    2013-01-01

    We describe a new electrostatic Particle-In-Cell (PIC) code in curvilinear geometry called Curvilinear PIC (CPIC). The code models the microscopic (kinetic) evolution of a plasma with the PIC method, coupled with an adaptive computational grid that can conform to arbitrarily shaped domains. CPIC is particularly suited for multiscale problems associated with the interaction of complex objects with plasmas. A map is introduced between the physical space and the logical space, where the grid is uniform and Cartesian. In CPIC, most operations are performed in logical space. CPIC was designed following criteria of versatility, robustness and performance. Its main features are the use of structured meshes, a scalable field solver based on the black box multigrid algorithm and a hybrid mover, where particles' position is in logical space while the velocity is in physical space. Test examples involving the interaction of a plasma with material boundaries are presented.

  15. The fusion crusts of stony meteorites: Implications for the atmospheric reprocessing of extraterrestrial materials

    Microsoft Academic Search

    Matthew J. Genge; Monica M. Grady

    1999-01-01

    Fusion crusts develop on all meteorites during their passage of the atmosphere but have been little studied. We have characterised the textures and compositions of the fusion crusts of 73 stony meteorites to identify the nature of meteorite ablation spheres (MAS) and constrain the processes operating during the entry heating. Most chondrite fusion crusts are porphyritic and dominated by olivine,

  16. Airtight container for the transfer of atmosphere-sensitive materials into vacuum-operated characterization instruments

    SciTech Connect

    Gaume, Romain M. [CREOL, the College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816-2700 (United States); Joubert, Lydia-Marie [Cell Sciences Imaging Facility, Beckman Center, Stanford University, Stanford, California 94305 (United States)

    2011-12-15

    This paper describes the design and operation of a simple airtight container devised to facilitate the transfer of atmosphere-sensitive samples from a glovebox to the vacuum chamber of an analytical instrument such as a scanning electron microscope. The use of this device for characterizing the microstructure of highly hygroscopic strontium iodide ceramics by scanning electron microscopy is illustrated as an application example.

  17. Real-time response system for the prediction of the atmospheric transport of hazardous materials

    Microsoft Academic Search

    S. Alhajraf; L. Al-Awadhi; S. Al-Fadala; A. Al-Khubaizi; A. R. Khan; S. Baby

    2005-01-01

    Human urge of exploiting earth resources has resulted into unprecedented industrial development in the last century resulting into production of large quantities of hazardous chemicals. Chemical, petrochemical, nuclear, biomedical and pharmaceutical industrial accidents release large quantities of hazardous chemicals into the atmosphere. The accidental discharge during production or storage or transportation have subjected the population to be exposed to exceptionally

  18. Study on an Atmospheric Pressure Plasma Jet and its Application in Etching Photo-Resistant Materials

    Microsoft Academic Search

    Haijiang Li; Shouguo Wang; Lingli Zhao; Tianchun Ye

    2004-01-01

    An atmospheric pressure radio-frequency plasma jet that can eject cold plasma has been developed. In this paper, the configuration of this type of plasma jet is illustrated and its discharge characteristics curves are studied with a current and a voltage probe. A thermal couple is used to measure the temperature distribution along the axis of the jet stream. The temperature

  19. Silicon-based elementary particle tracking system: Materials science and mechanical engineering design

    SciTech Connect

    Miller, W.O.; Gamble, M.T.; Thompson, T.C.; Hanlon, J.A.

    1993-01-01

    Research and development of the mechanical, cooling, and structural design aspects of a silicon detector-based elementary particle tracking system has been performed. Achieving stringent system precision, stability, and mass requirements necessitated the use of graphite fiber-reinforced cyanate-ester (C-E) resins. Mechanical test results of the effects of butane, ionizing radiation, and a combination of both on the mechanical properties of these materials are presented, as well as progress on developing compression molding of an ultralightweight graphite composite ring structure and TV holography-based noninvasive evaluation.

  20. Silicon-based elementary particle tracking system: Materials science and mechanical engineering design

    SciTech Connect

    Miller, W.O.; Gamble, M.T.; Thompson, T.C.; Hanlon, J.A.

    1993-05-01

    Research and development of the mechanical, cooling, and structural design aspects of a silicon detector-based elementary particle tracking system has been performed. Achieving stringent system precision, stability, and mass requirements necessitated the use of graphite fiber-reinforced cyanate-ester (C-E) resins. Mechanical test results of the effects of butane, ionizing radiation, and a combination of both on the mechanical properties of these materials are presented, as well as progress on developing compression molding of an ultralightweight graphite composite ring structure and TV holography-based noninvasive evaluation.

  1. Source apportionment of fine particles at urban background and rural sites in the UK atmosphere

    NASA Astrophysics Data System (ADS)

    Yin, Jianxin; Harrison, Roy M.; Chen, Qiang; Rutter, Andrew; Schauer, James J.

    2010-02-01

    Airborne fine particulate matter (PM 2.5) has been collected at two sites in the West Midlands conurbation, UK, representing urban background and rural locations. Chemical analyses have been carried out for major anions, trace metals, total OC and EC, and for individual organic marker species including n-alkanes, hopanes, PAHs, organic acids and sterols. Source apportionment has been conducted using both a pragmatic mass closure model and the US EPA chemical mass balance (CMB) model. The pragmatic mass closure model is well able to account for the measured PM 2.5 mass in terms of chemical/source components, and the chemical mass balance model has been used to apportion the carbonaceous component of the aerosol. The dominant components of PM 2.5 at both sites are secondary inorganic (sulphate and nitrate) and carbonaceous particles. The CMB model shows the latter to arise mainly from road traffic sources, with smaller contributions from vegetative detritus, wood smoke, natural gas, coal, and dust/soil. The CMB model also identifies an important component of the organic aerosol not associated with these primary sources, which correlates very strongly with secondary organic aerosol estimated from the OC/EC ratio. The split between different automotive source types does not relate well to UK emission inventories, and may indicate that CMB source profiles from North American studies and different carbon analysis protocols may lead to erroneous conclusions.

  2. Atmospheric dust

    NSDL National Science Digital Library

    University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

    2003-01-01

    What is the purpose of dust in the atmosphere? On this activity page, part of an interactive laboratory series for grades 8-12, students read about the need for dust in the atmosphere as an agent for condensation. The addition of dust particles to the atmosphere by airplanes introduces students to the concept of cloud seeding and influencing the chance of rain in an area. Copyright 2005 Eisenhower National Clearinghouse

  3. Manufacture of nickel base composite materials with dispersed glass particles by the powder metallurgy method. Part I

    Microsoft Academic Search

    B. L. Rudoi; M. Kh. Shorshorov; G. M. Matveev; B. A. Borok; R. P. Shchegoleva

    1974-01-01

    1.A technique has been developed for the manufacture of rods of nickel base composite materials containing crystallizing glass particles. Such rods are characterized by a uniform distribution of dispersed phase particles throughout the metal and have densities close to theoretical.2.A study was made of the specific load in the extrustion of sintered compacts as a function of the amount and

  4. Hybrid algorithm of minimum relative entropy-particle swarm optimization with adjustment parameters for gas source term identification in atmosphere

    NASA Astrophysics Data System (ADS)

    Ma, Denglong; Wang, Simin; Zhang, Zaoxiao

    2014-09-01

    In order to identify the source term of gas emission in atmosphere, an improved hybrid algorithm combined with the minimum relative entropy (MRE) and particle swarm optimization (PSO) method was presented. Not only are the estimated source parameters obtained, but also the confidence intervals at some probability levels. If only the source strength was required to be determined, the problem can be viewed as a linear inverse problem directly, which can be solved by original MRE method successfully. When both source strength and location are unknown, the common gas dispersion model should be transformed to be a linear system. Although the transformed linear model has some differences from that in original MRE method, satisfied estimation results were still obtained by adding iteratively adaptive adjustment parameters in the MRE-PSO method. The dependence of the MRE-PSO method on prior information such as lower and upper bound, prior expected values and noises were also discussed. The results showed that the confidence intervals and estimated parameters are influenced little by the prior bounds and expected values, but the errors affect the estimation results greatly. The simulation and experiment verification results showed that the MRE-PSO method is able to identify the source parameters with satisfied results. Finally, the error model was probed and then it was added in the MRE-PSO method. The addition of error model improves the performance of the identification method. Therefore, the MRE-PSO method with adjustment parameters proposed in this paper is a potential good method to resolve inverse problem in atmosphere environment.

  5. Analysis of plasma particle and energy fluxes to material surfaces from tokamak edge turbulence simulations

    NASA Astrophysics Data System (ADS)

    Umansky, M. V.; Cohen, B. I.; Rognlien, T. D.; Boedo, J. A.; Rudakov, D. L.

    2012-10-01

    Recent BOUT simulations of edge plasma turbulence in L-mode regime in the boundary region of DIII-D tokamak have demonstrated reasonable match with key edge diagnostics [1]. Order-of-magnitude level agreement has been found in the characteristic amplitude, wavenumber, and frequency of turbulent fluctuations, as compared with experimental data from reciprocating edge Langmuir probe and Beam Emission Spectroscopy systems. Owing to this encouraging agreement, output data from these simulations are analyzed to get insights on physical mechanisms and properties of plasma particle and energy fluxes to material surfaces. Of particular interest is plasma turbulence propagating into, or generated in, the far scrape-off layer region where plasma interacts with material walls. Results of statistical analyses of simulated turbulence plasma transport will be presented and physical implications will be discussed. [4pt] [1] B.I. Cohen et al., APS-DPP 2012

  6. Effect of cluster/particle deposition on atmospheric pressure chemical vapor deposition of SiO2 from four gaseous organic Si-containing precursors and ozone

    NASA Astrophysics Data System (ADS)

    Fujimoto, Toshiyuki; Okuyama, Kikuo; Yamada, Satoshi; Adachi, Motoaki

    1999-04-01

    In order to analyze the particle generation and its effect on the SiO2 thin film in an atmospheric pressure chemical vapor deposition (APCVD) process using four organic silicon vapors and ozone gas, gas-phase particle generation, growth, transportation and vapor-cluster/particle codeposition processes were studied experimentally and theoretically using a flow-type vertical tube reactor. Decomposition reaction rates of four organic silicon vapors (tetraethylorthosilicate, triethoxysilane, tetramethylorthosilicate, and octamethylcyclotetrasiloxane) due to the O?oxidation were determined by arranging the number concentrations of the generated particles in Arrhenius plots. The obtained activation energies and frequency factors of reaction rate constants were used to simulate the vapor-cluster/particle codeposition in the CVD process. In the numerical simulation, computational fluid dynamics equations (continuity, momentum, and energy conservation equations) were solved to evaluate the gas velocity, vapor concentration, and temperature profile inside the reactor. Particle population balance equations based on discrete-sectional presentation for the particle size spectrum were solved coupling with diffusion equations of vapors and clusters/particles. This numerical simulation code could explain the vapor-cluster/particle codeposition in the thin film preparation by the APCVD process. The film growth rate and the surface morphology of the film could be reasonably explained by the deposition flux and the size of deposited clusters/particles obtained as numerical simulation results, respectively.

  7. CPIC: a curvilinear Particle-In-Cell code for plasma-material interaction studies

    NASA Astrophysics Data System (ADS)

    Delzanno, G.; Camporeale, E.; Moulton, J. D.; Borovsky, J. E.; MacDonald, E.; Thomsen, M. F.

    2012-12-01

    We present a recently developed Particle-In-Cell (PIC) code in curvilinear geometry called CPIC (Curvilinear PIC) [1], where the standard PIC algorithm is coupled with a grid generation/adaptation strategy. Through the grid generator, which maps the physical domain to a logical domain where the grid is uniform and Cartesian, the code can simulate domains of arbitrary complexity, including the interaction of complex objects with a plasma. At present the code is electrostatic. Poisson's equation (in logical space) can be solved with either an iterative method based on the Conjugate Gradient (CG) or the Generalized Minimal Residual (GMRES) coupled with a multigrid solver used as a preconditioner, or directly with multigrid. The multigrid strategy is critical for the solver to perform optimally or nearly optimally as the dimension of the problem increases. CPIC also features a hybrid particle mover, where the computational particles are characterized by position in logical space and velocity in physical space. The advantage of a hybrid mover, as opposed to more conventional movers that move particles directly in the physical space, is that the interpolation of the particles in logical space is straightforward and computationally inexpensive, since one does not have to track the position of the particle. We will present our latest progress on the development of the code and document the code performance on standard plasma-physics tests. Then we will present the (preliminary) application of the code to a basic dynamic-charging problem, namely the charging and shielding of a spherical spacecraft in a magnetized plasma for various level of magnetization and including the pulsed emission of an electron beam from the spacecraft. The dynamical evolution of the sheath and the time-dependent current collection will be described. This study is in support of the ConnEx mission concept to use an electron beam from a magnetospheric spacecraft to trace magnetic field lines from the magnetosphere to the ionosphere [2]. [1] G.L. Delzanno, E. Camporeale, "CPIC: a new Particle-in-Cell code for plasma-material interaction studies", in preparation (2012). [2] J.E. Borovsky, D.J. McComas, M.F. Thomsen, J.L. Burch, J. Cravens, C.J. Pollock, T.E. Moore, and S.B. Mende, "Magnetosphere-Ionosphere Observatory (MIO): A multisatellite mission designed to solve the problem of what generates auroral arcs," Eos. Trans. Amer. Geophys. Union 79 (45), F744 (2000).

  8. Competing effects of particle and medium inertia on particle diffusion in viscoelastic materials, and their ramifications for passive microrheology.

    PubMed

    Indei, Tsutomu; Schieber, Jay D; Córdoba, Andrés

    2012-04-01

    We analyze the appropriate form for the generalized Stokes-Einstein relation (GSER) for viscoelastic solids and fluids when bead inertia and medium inertia are taken into account, which we call the inertial GSER. It was previously shown for Maxwell fluids that the Basset (or Boussinesq) force arising from medium inertia can act purely dissipatively at high frequencies, where elasticity of the medium is dominant. In order to elucidate the cause of this counterintuitive result, we consider Brownian motion in a purely elastic solid where ordinary Stokes-type dissipation is not possible. The fluctuation-dissipation theorem requires the presence of a dissipative mechanism for the particle to experience fluctuating Brownian forces in a purely elastic solid. We show that the mechanism for such dissipation arises from the radiation of elastic waves toward the system boundaries. The frictional force associated with this mechanism is the Basset force, and it exists only when medium inertia is taken into consideration in the analysis of such a system. We consider first a one-dimensional harmonic lattice where all terms in the generalized Langevin equation--i.e., the elastic term, the memory kernel, and Brownian forces-can be found analytically from projection-operator methods. We show that the dissipation is purely from radiation of elastic waves. A similar analysis is made on a particle in a continuum, three-dimensional purely elastic solid, where the memory kernel is determined from continuum mechanics. Again, dissipation arises only from radiation of elastic shear waves toward infinite boundaries when medium inertia is taken into account. If the medium is a viscoelastic solid, Stokes-type dissipation is possible in addition to radiational dissipation so that the wave decays at the penetration depth. Inertial motion of the bead couples with the elasticity of the viscoelastic material, resulting in a possible resonant oscillation of the mean-square displacement (MSD) of the bead. On the other hand, medium inertia (the Basset force) tends to attenuate the oscillations by the dissipation mechanism described above. Thus competition between bead inertia and medium inertia determines whether or not the MSD oscillates. We find that, if the medium density is larger than 4/7 of the bead density, the Basset damping will suppress oscillations in the MSD; this criterion is sufficient but not necessary to present oscillations. PMID:22680480

  9. A theory for plastic-bonded materials with a bimodal size distribution of filler particles

    NASA Astrophysics Data System (ADS)

    Clements, B. E.; Mas, E. M.

    2004-05-01

    Plastic-bonded materials are composites consisting of grains of filler material embedded in a polymeric matrix. A micromechanics model is proposed for investigating the mechanical behaviour of plastic-bonded materials having two disparate grain sizes. A hybrid theory is proposed to handle some aspects of the bimodal grain size distribution. Our model uses the first-order method of cells with an eight-cell representative volume element where one of the eight cells contains a large grain and the seven remaining cells contain a mixture of small grains embedded in the polymeric binder material. A Mori-Tanaka-based analysis is used to describe the small grain-binder mechanical response. The small grains in this analysis are assumed to be spherical and uniformly distributed in the binder. In this work, we use the explosive PBX 9501, in its unreacted state, as our test system. The explosive grain particle size distribution of PBX 9501 consists of two broad peaks centred at approximately 1 and 200 µm. The constitutive behaviour of the large explosive grains are assumed to be elastic-plastic and damage by way of micro-crack brittle fracture. Only linear elasticity of the small grains is considered. The rate and temperature dependence of the mechanical response of the polymer binder is accounted for by a generalized Maxwell viscoelasticity model. The theoretical uniaxial stress-strain response for PBX 9501 is reported for quasi-static and split Hopkinson pressure bar loading rates and compared to experimental measurements.

  10. Comparison of quantification methods to measure fire-derived (black\\/elemental) carbon in soils and sediments using reference materials from soil, water, sediment and the atmosphere

    Microsoft Academic Search

    Karen Hammes; Michael W. I. Schmidt; Ronald J. Smernik; Lloyd A. Currie; William P. Ball; Thanh H. Nguyen; Patrick Louchouarn; Stephane Houel; Örjan Gustafsson; Marie Elmquist; Gerard Cornelissen; Jan O. Skjemstad; Caroline A. Masiello; Jianzhong Song; Ping'an Peng; Siddhartha Mitra; Joshua C. Dunn; Patrick G. Hatcher; William C. Hockaday; Dwight M. Smith; Christoph Hartkopf-Fröder; Axel Böhmer; Burkhard Lüer; Barry J. Huebert; Wulf Amelung; Sonja Brodowski; Lin Huang; Wendy Zhang; Philip M. Gschwend; D. Xanat Flores-Cervantes; Claude Largeau; Jean-Noël Rouzaud; Cornelia Rumpel; Georg Guggenberger; Klaus Kaiser; Andrei Rodionov; Francisco J. Gonzalez-Vila; José A. Gonzalez-Perez; José M. de la Rosa; David A. C. Manning; Elisa López-Capél; Luyi Ding

    2007-01-01

    Black carbon (BC), the product of incomplete combustion of fossil fuels and biomass (called elemental carbon (EC) in atmospheric sciences), was quantified in 12 different materials by 17 laboratories from different disciplines, using seven different methods. The materials were divided into three classes: (1) potentially interfering materials, (2) laboratory-produced BC-rich materials, and (3) BC-containing environmental matrices (from soil, water, sediment,

  11. Complex experiment on stydying the microphysical, chemical, and optical propertires of aerosol particles and estimating the contribution of atmospheric aerosol to Earth radiation budget

    NASA Astrophysics Data System (ADS)

    Matvienko, G. G.; Belan, B. D.; Panchenko, M. V.; Romanovskii, O. A.; Sakerin, S. M.; Kabanov, D. M.; Turchinovich, S. A.; Turchinovich, Y. S.; Eremina, T. A.; Kozlov, V. S.; Terpugova, S. A.; Pol'kin, V. V.; Yausheva, E. P.; Chernov, D. G.; Zhuravleva, T. B.; Bedareva, T. V.; Odintsov, S. L.; Burlakov, V. D.; Nevzorov, A. V.; Arshinov, M. Yu.; Ivlev, G. A.; Savkin, D. E.; Fofonov, A. V.; Gladkikh, V. A.; Kamardin, A. P.; Balin, Yu. S.; Kokhanenko, G. P.; Penner, I. E.; Samoilova, S. V.; Antokhin, P. N.; Arshinova, V. G.; Davydov, D. K.; Kozlov, A. V.; Pestunov, D. A.; Rasskazchikova, T. M.; Simonenkov, D. V.; Sklyadneva, T. K.; Tolmachev, G. N.; Belan, S. B.; Shmargunov, V. P.; Kozlov, A. S.; Malyshkin, S. B.

    2015-06-01

    The primary objective of the Complex Aerosol Experiment was measurement of microphysical, chemical, and optical properties of aerosol particles in the surface air layer and free atmosphere. The measurement data were used to retrieve the whole set of aerosol optical parameters, necessary for radiation calculations. Three measurement cycles were performed within the Experiment during 2013: in spring, when the aerosol generation is maximal; in summer (July), when atmospheric boundary layer altitude and, hence, mixing layer altitude are maximal; and in late summer - early autumn, during the period of nucleation of secondary particles. Numerical calculations were compared with measurements of downward solar fluxes on the Earth's surface, performed in the clear-sky atmosphere in summer periods in 2010-2012 in a background region of the boreal zone of Siberia. It has been shown that, taking into account the instrumental errors and errors of atmospheric parameters, the relative differences between model and experimental values of direct and global solar radiation fluxes do not exceed, on the average, 1 and 3%, respectively. Thus, independently obtained data on the optical, meteorological, and microphysical parameters of the atmosphere allows intercalibration and inter-complement of the data and, thereby, provide for qualitatively new information which explains the physical nature of the processes that form the vertical structure of the aerosol field.

  12. Particle-in-Cell Simulation for the Control of Electron Energy Distribution of Dielectric Barrier Discharges at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Bae, Hyo Won; Yel Lee, Jung; Lee, Ho-Jun; Lee, Hae June

    2011-10-01

    Recently, atmospheric pressure plasmas attract lots of interests for the useful applications such as surface modification and bio-medical treatment. In this study, a particle-in-cell Monte Carlo collision (PIC-MCC) simulation was adopted to investigate the discharge characteristics of a planar micro dielectric barrier discharge (DBD) with a driving frequency from 1 MHz to 50 MHz and with a gap distance from 60 to 500 micrometers. The variation of control parameters such as the gap distance, the driving wave form, and the applied voltage results in the change in the electron energy distribution function (EEDF). Through the relation between the ionization mean free path and the gap size, a significant change of EEDFs is achievable with the decrease of gap distance. Therefore, it is possible to categorize the operation range of DBDs for its applications by controlling the interactions between plasmas and neutral gas for the generation of preferable radicals. This work was supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 20104010100670).

  13. Particle scale modeling of material removal and surface roughness in chemical mechanical polishing

    NASA Astrophysics Data System (ADS)

    Yeruva, Suresh Babu

    2005-11-01

    Chemical mechanical polishing (CMP) is widely adopted in producing excellent local and global planarization of microelectronic devices. It has been demonstrated experimentally that the polishing performance is a result of the synergistic effect of both the chemicals and the particles involved in CMP. However, the fundamental mechanisms of material removal and the interactions of the chemical and mechanical effects are not well understood. A comprehensive model for CMP was developed taking into account both the chemical and mechanical effects for slurries with a given particle size distribution. The model developed (PERC II) is based on a previously developed model (PERC I). The chemical aspect is attributed to the chemical modification of the surface layer due to slurry chemistry, whereas the mechanical aspect is incorporated by indentation of particles into the modified layer and the substrate depending on the operating conditions. In this study, the effects of particle size and pad asperity distributions are included in the model. The contact area of pad with wafer was measured in dry and wet conditions in different pH solutions using optical microscopy and Fourier transform infrared spectroscopy respectively. Pad surface mechanical properties in dry and wet states were also investigated using atomic force microscopy. The contact area results obtained were utilized in modeling to estimate the pad modulus leading to pad-wafer contact stress distribution. The predictions of the model show a reasonable agreement with the experimental data. The model is validated for oxide and metal CMP systems. The PERC II model not only predicts the overall removal rate, but also the surface roughness of the polished wafer in selected systems. The developed model can be used to optimize the current CMP systems and provide insights into future CMP endeavors.

  14. Tree bark suber-included particles: A long-term accumulation site for elements of atmospheric origin

    NASA Astrophysics Data System (ADS)

    Catinon, Mickaël; Ayrault, Sophie; Spadini, Lorenzo; Boudouma, Omar; Asta, Juliette; Tissut, Michel; Ravanel, Patrick

    2011-02-01

    The deposition of atmospheric elements on and into the bark of 4-year-old Fraxinus excelsior L. was studied. The elemental composition of the suber tissue was established through ICP-MS analysis and the presence of solid mineral particles included in this suber was established and described through SEM-EDX. Fractionation of the suber elements mixture was obtained after ashing at 550 °C through successive water (C fraction) and HNO 3 2 M (D fraction) extraction, leading to an insoluble residue mainly composed of the solid mineral particles (E fraction). The triplicated % weight of C, D and E were respectively 34.4 ± 2.7, 64.8 ± 2.7 and 0.8 ± 0.1% of the suber ashes weight. The main component of C was K, of D was Ca. Noticeable amounts of Mg were also observed in D. The E fraction, composed of insoluble particles, was mostly constituted of geogenic products, with elements such as Si, Al, K, Mg, representing primary minerals. E also contained Ca 3(PO 4) 2 and concentrated the main part of Pb and Fe. Moreover, The SEM-EDX analysis evidenced that this fraction also concentrated several types of fly ashes of industrial origin. The study of the distribution between C, D and E was analysed through ICP-MS with respect to their origin. The origin of the elements found in such bark was either geogenic (clay, micas, quartz…), anthropogenic or biogenic (for instance large amounts of solid Ca organic salts having a storage role). As opposed to the E fraction, the C fraction, mainly composed of highly soluble K+ is characteristic of a biological pool of plant origin. In fraction D, the very high amount of Ca++ corresponds to two different origins: biological or acid soluble minerals such as calcite. Furthermore, the D fraction contains the most part of pollutants of anthropic origin such as Zn, Cu, Ni, Co, Cd. As a whole, the fractionation procedure of the suber samples allows to separate elements as a function of their origin but also gives valuable information on distribution and speciation of trace elements.

  15. The LDCE Particle Impact Experiment as flown on STS-46. [limited duration space environment candidate materials exposure (LDCE)

    NASA Technical Reports Server (NTRS)

    Maag, Carl R.; Tanner, William G.; Borg, Janet; Bibring, Jean-Pierre; Alexander, W. Merle; Maag, Andrew J.

    1992-01-01

    Many materials and techniques have been developed by the authors to sample the flux of particles in Low Earth Orbit (LEO). Though regular in-site sampling of the flux in LEO the materials and techniques have produced data which compliment the data now being amassed by the Long Duration Exposure Facility (LDEF) research activities. Orbital debris models have not been able to describe the flux of particles with d sub p less than or = 0.05 cm, because of the lack of data. Even though LDEF will provide a much needed baseline flux measurement, the continuous monitoring of micron and sub-micron size particles must be carried out. A flight experiment was conducted on the Space Shuttle as part of the LDCE payload to develop an understanding of the Spatial Density (concentration) as a function of size (mass) for particle sizes 1 x 10(exp 6) cm and larger. In addition to the enumeration of particle impacts, it is the intent of the experiment that hypervelocity particles be captured and returned intact. Measurements will be performed post flight to determine the flux density, diameters, and subsequent effects on various optical, thermal control and structural materials. In addition to these principal measurements, the Particle Impact Experiment (PIE) also provides a structure and sample holders for the exposure of passive material samples to the space environment, e.g., thermal cycling, and atomic oxygen, etc. The experiment will measure the optical property changes of mirrors and will provide the fluence of the ambient atomic oxygen environment to other payload experimenters. In order to augment the amount of material returned in a form which can be analyzed, the survivability of the experiment as well as the captured particles will be assessed. Using Sandia National Laboratory's hydrodynamic computer code CTH, hypervelocity impacts on the materials which comprise the experiments have been investigated and the progress of these studies are reported.

  16. Composition-tailored synthesis of gradient transition metal precursor particles for lithium-ion battery cathode materials.

    SciTech Connect

    Koenig, G. M.; Belharouak, I.; Deng, H.; Amine, K.; Sun, Y. K. (Chemical Sciences and Engineering Division)

    2011-04-12

    We report the tailored synthesis of particles with internal gradients in transition metal composition aided by the use of a general process model. Tailored synthesis of transition metal particles was achieved using a coprecipitation reaction with tunable control over the process conditions. Gradients in the internal composition of the particles was monitored and confirmed experimentally by analysis of particles collected during regularly timed intervals. Particles collected from the reactor at the end of the process were used as the precursor material for the solid-state synthesis of Li{sub 1.2}(Mn{sub 0.62}Ni{sub 0.38}){sub 0.8}O{sub 2}, which was electrochemically evaluated as the active cathode material in a lithium battery. The Li{sub 1.2}(Mn{sub 0.62}Ni{sub 0.38}){sub 0.8}O{sub 2} material was the first example of a structurally integrated multiphase material with a tailored internal gradient in relative transition metal composition as the active cathode material in a lithium-ion battery. We believe our general synthesis strategy may be applied to produce a variety of new cathode materials with tunable interior, surface, and overall relative transition metal compositions.

  17. Charged-particle emission from dielectric materials initiated by a tunable picosecond mid-infrared laser

    NASA Astrophysics Data System (ADS)

    Ermer, David R.; Papantonakis, Michael R.; Baltz-Knorr, Michelle; Haglund, Richard F., Jr.

    2000-03-01

    In the ultraviolet, visible and near-infrared, single and multiphoton electronic transitions can explain the production and emission of charged atoms, molecules and photoelectrons during laser ablation and desorption. However, the process of charge transfer and ionization during ablation of dielectrics in the mid-infrared is not well understood. Even though significant electronic excitation is unlikely, copious emission of charged particles, e.g. atoms, molecules and electrons, is observed. No evidence of laser plume interactions is observed and inverse Bremsstrahlung (IB) is ruled out as a primary ionization/charge transfer mechanism. By irradiating with an ultrashort pulse-width mid-infrared laser tuned to a vibrational resonance it is possible to generate a high vibrational excitation density in dielectric materials. This high excitation density creates a non- equilibrium state of matter that exists until the deposited energy fully thermalizes. In this paper we report measurements of the kinetic energy of ions and electrons from CaCO3, NaNO3 and dihydroxybenzoic (DHB) acid that are highly non- thermal. This non-thermal energy distribution is evidence that the primary production of charged species occurs while the material is in a non-equilibrium state. The fact that it occurs in quite different materials, and without some of the characteristic signatures of electronically induced desorption and ionization, points toward a new mechanism.

  18. Particle size effect on strength, failure, and shock behavior in polytetrafluoroethylene-Al-W granular composite materials

    NASA Astrophysics Data System (ADS)

    Herbold, E. B.; Nesterenko, V. F.; Benson, D. J.; Cai, J.; Vecchio, K. S.; Jiang, F.; Addiss, J. W.; Walley, S. M.; Proud, W. G.

    2008-11-01

    The variation of metallic particle size and sample porosity significantly alters the dynamic mechanical properties of high density granular composite materials processed using a cold isostatically pressed mixture of polytetrafluoroethylene (PTFE), aluminum (Al), and tungsten (W) powders. Quasistatic and dynamic experiments are performed with identical constituent mass fractions with variations in the size of the W particles and pressing conditions. The relatively weak polymer matrix allows the strength and fracture modes of this material to be governed by the granular type behavior of agglomerated metal particles. A higher ultimate compressive strength was observed in relatively high porosity samples with small W particles compared to those with coarse W particles in all experiments. Mesoscale granular force chains of the metallic particles explain this unusual phenomenon as observed in hydrocode simulations of a drop-weight test. Macrocracks forming below the critical failure strain for the matrix and unusual behavior due to a competition between densification and fracture in dynamic tests of porous samples were also observed. Numerical modeling of shock loading of this granular composite material demonstrated that the internal energy, specifically thermal energy, of the soft PTFE matrix can be tailored by the W particle size distribution.

  19. Waveguides in three-dimensional photonic bandgap materials for particle-accelerator on a chip architectures.

    PubMed

    Staude, Isabelle; McGuinness, Christopher; Frölich, Andreas; Byer, Robert L; Colby, Eric; Wegener, Martin

    2012-02-27

    The quest for less costly and more compact high-energy particle accelerators makes research on alternative acceleration mechanisms an important enterprise. From the multitude of suggested concepts, the photonic accelerator design by B. M. Cowan [Phys. Rev. ST Accel. Beams 11, 011301 (2008)] stands out by its distinct potential of creating an accelerator on a chip [Proposal E-163, SLAC (2001)]. Herein, electrons are accelerated by the axial electric field of a strongly confined optical mode of an air waveguide within a silicon-based three-dimensional photonic band-gap material. Using a combination of direct laser writing and silicon double inversion, we here present the first experimental realization of this complex structure. Optical spectroscopy provides unambiguous evidence for the existence of an accelerating waveguide mode with axial polarization. PMID:22418367

  20. Effect of dielectric material on bipolar nanosecond pulse diffuse dielectric barrier discharge in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Tang, Kai; Wang, Wenchun; Yang, Dezheng; Zhang, Shuai; Yang, Yang; Liu, Zhijie

    2013-08-01

    In this paper, dielectric plates made by ceramic, quartz and polytetrafluoroethylene (PTFE) respectively are employed to generate low gas temperature, diffuse dielectric barrier discharge plasma by using a needle-plate electrode configuration in air at atmospheric pressure. Both discharge images and the optical emission spectra are obtained while ceramic, quartz and PTFE are used as dielectric material. Plasma gas temperature is also calculated by comparing the experimental emission spectra with the best fitted spectra of N2 (C3?u ? B3?g 1-3) and N2 (C3?u ? B3?g 0-2). The effects of different pulse peak voltages and gas gap distances on the emission intensity of N2 (C3?u ? B3?g, 0-0, 337.1 nm) and the plasma area on dielectric surface are investigated while ceramic, quartz and PTFE are used as dielectric material. It is found that the permittivity of dielectric material plays an important role in the discharge homogeneity, plasma gas temperature, emission spectra intensity of the discharge, etc. Dielectric with higher permittivity i.e., ceramic means brighter discharge luminosity and stronger emission spectra intensity of N2 (C3?u ? B3?g, 0-0, 337.1 nm) among the three dielectric materials. However, more homogeneous, larger plasma area on dielectric surface and lower plasma gas temperature can be obtained under dielectric with lower permittivity i.e., PTFE. The emission spectra intensity and plasma gas temperature of the discharge while the dielectric plate is made by quartz are smaller than that while ceramic is used as dielectric material and bigger than that when PTFE is used as dielectric material.

  1. Titan's aerosols. I - Laboratory investigations of shapes, size distributions, and aggregation of particles produced by UV photolysis of model Titan atmospheres

    NASA Technical Reports Server (NTRS)

    Scattergood, Thomas W.; Lau, Edmond Y.; Stone, Bradley M.

    1992-01-01

    Experiments in which C2H2, C2H4, and HCN were photolyzed separately and as a mixture in UV light have been conducted in order to ascertain the physical properties of model Titan atmosphere aerosols. Aerosols formed from photolysis of C2H4 were physically similar to those formed from C2H2; protolysis of HCN rapidly generated particles that did not grow to sizes greater than 0.09 microns. While the formation of particles from C4H2 was observed within minutes, formation was slowed by a factor of 4 when C2H2 and HCN were added.

  2. PREPARATION AND CHARACTERIZATION OF NANOSTRUCTURED GRANULAR SUPPORT PARTICLES AND CATALYTIC MATERIALS

    SciTech Connect

    Zhenchen Zhong

    2002-01-15

    We have set up successfully two experimental systems during the past time of the project. The first system is sol-gel chemical method for preparing {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, Cr{sub 2}O{sub 3} granular support particles. The second system is the laser-induced solution deposition (LISD) technique for nanoparticle catalysts containing Fe/Cu, and Co/Cu on the granular support. We have successfully deposited {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, Cr{sub 2}O{sub 3} granular support particles by sol-gel method and Co and CoO nanoparticles by LISD novel fabrication technique. The characterization methods we have used include scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM) and X-Ray diffraction (XRD). The research toward to the proposed direction is in good progress. We have given three presentations in national and local materials meetings and have submitted another two papers in another two key national meetings in nanotechnology and American Physical Annual March Meeting 2002. A couple of papers are in preparation.

  3. Force chains as the link between particle and bulk friction angles in granular material

    NASA Astrophysics Data System (ADS)

    Booth, A. M.; Hurley, R.; Lamb, M. P.; Andrade, J.

    2014-12-01

    From initial motion of sediment in rivers, to landslides and rock fall, predictions of granular transport typically rely on a Mohr-Coulomb failure criterion in which resistance to motion is parameterized by a friction angle. Empirically determined friction angles are generally large and variable when applied to the movement of a single grain as in fluvial transport, but are generally smaller and more consistent when applied to effectively infinite numbers of grains as in soil mechanics. We propose that these two end member definitions of friction angle are linked by transmission of force along grain to grain contacts (i.e. granular force chains) over length scales of 1 to ~ 20 grain diameters. A numerical model based on the statistics of individual grain-pocket friction angles, targeted physical experiments, and discrete element modeling all demonstrate that the maximum stable angle of granular material on a rough bed decreases by up to 15° as the number of potentially unstable particles increases. Decreased stability with increasing number of grains occurs as force chains become longer and more effective at dislodging downslope grains. The average friction angle for an assembly of particles therefore emerges directly from the statistics of the individual grain-pocket friction angles and is distinct from the sliding coefficient of friction acting between grains. Small clusters of grains abound at the earth's surface, and we suggest that force chains are important for a wide variety of subaerial and subaqueous sediment transport processes.

  4. Trends in atmospheric carbon dioxide concentration at the Oligocene-Miocene transition reconstructed by using fossil plant material

    NASA Astrophysics Data System (ADS)

    Roth-Nebelsick, Anita; Grein, Michaela; Konrad, Wilfried

    2010-05-01

    The Oligocene-Miocene transition represents a period in earth history marked by rapid cooling and glaciation of Antarctica, accompanied by a positive shift in ?13C and ?18O. According to modelling studies, formation of substantial Antarctic ice sheets requires pCO2atm to decrease below 500 ppm. Various proxies (such as Boron isotopes and ?13C isotopes derived from marine organisms, stomatal density of terrestrial fossil plants) indicate a substantial general trend of decline in atmospheric CO2, from the Late Oligocene to the Early Miocene, from about 600 to 300 ppm, with values of about 450 to 300 ppm for the Oligocene-Miocene transition. Here we use stomatal density values of fossil plants spanning a time interval from the Middle Oligocene to the Early Miocene. This proxy is based on the stomatal density response to atmospheric CO2. We applied, however, an approach that is based on a mechanistic model which couples photosynthesis and transpiration to diffusion, supplemented by an ecophysiological optimization model that provides an optimum use of water (transpiration). This optimization principle describes the adjustment of stomatal conductance in such a way that the maximum possible photosynthesis is accomplished at a minimum of water loss. This optimization phenomenon is confirmed for extant terrestrial plants. The model requires palaeoenvironmental conditions (such as atmospheric humidity, temperature, wind velocity and water availability) and anatomical data (such as depth, length and width of stomatal pore, thickness of assimilation tissue and leaf length). Fossil plant material from several European sites is considered so far: The Weisselster basin in Saxony (Germany), the clay pit Unterfeld near Wiesloch-Frauenweiler (Germany), and Oberdorf in Styria (Austria). In order to obtain meaningful results, we investigate several species of different families: Eotrigonbalanus furcinervis (Fagaceae), Quercus rhenana (Fagaceae), Quercus praerhenana (Fagaceae), Laurophyllum pseudoprinceps (Lauraceae), Laurophyllum acutimontanum (Laurceae) and Platanus neptunii (Platanaceae). In this contribution, we present first results of atmospheric carbon dioxide spanning a time interval from the Late Oligocene to the early Miocene, calculated from fossil Eotrigonobalanus furcinervis (Fagaceae) and the two Lauraceae species, Laurophyllum pseudoprinceps and Laurophyllum acutimontanum (Weisselster basin). The combined results indicate preliminary values for atmospheric carbon dioxide concentration of about 360 ppm in the Late Oligocene, 650 ppm at the Oligocene-Miocene transition and 340 ppm in the Early Miocene.

  5. The flux of bio- and lithogenic material associated with sinking particles in the mesopelagic “twilight zone” of the northwest and North Central Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Lamborg, C. H.; Buesseler, K. O.; Valdes, J.; Bertrand, C. H.; Bidigare, R.; Manganini, S.; Pike, S.; Steinberg, D.; Trull, T.; Wilson, S.

    2008-07-01

    As part of the VERTIGO program, we collected and analyzed sinking particles using tethered and neutrally buoyant sediment traps at three depths in the oceanic mesopelagic zone and at two biogeochemically contrasting sites (N. Central Pacific at ALOHA; N. Pacific Western Subarctic Gyre at K2). This effort represented the first large-scale use of neutrally buoyant traps and represents a significant step forward in the study of the marine biological pump. In this paper, we present the results of mass, macronutrient, biominerals and phytoplankton pigment determinations made on these samples. The impact of a variety of potential collection biases were examined, including those from in-trap particle degradation, zooplankton swimmers and poisons. Though these factors have been observed to affect results in other programs, we found them to have relatively little impact on measured fluxes in this study. There was evidence, however, that the neutrally buoyant traps performed better than the tethered traps in terms of flux accuracy during one deployment, possibly because of improved large particle collection efficiency. Fluxes of material exhibited three different patterns through the mesopelagic: increasing, decreasing and constant with depth. Decreasing fluxes with depth were observed for all biogenic material formed in the euphotic zone. The attenuation of flux with depth was not the same for all components, however, with phytoplankton pigments exhibiting the greatest degradation with depth and particulate inorganic carbon the least. Organic carbon and nitrogen showed a very high correlation in these samples, with little evidence of different attenuation length scales. Increasing fluxes with depth were observed for particulate Ba at both sites and Al at K2. The increases in Ba are attributed to the formation of barite in degrading particles, while increasing Al at K2 was the result of lateral inputs from a continental shelf/slope. Constant fluxes with depth were observed for Al at ALOHA, where fluxes appeared to be in steady state with atmospheric dust deposition. The mesopelagic zone at K2 was observed to attenuate particle flux less than at ALOHA, and with a higher POC/PIC ("rain") ratio. These two factors combine to imply that the Subarctic province had a much more efficient biological pump than had the subtropical gyre during our occupations. This could be the result of either faster sinking particles, generated from grazing by large zooplankton, or inherently slower particle degradation rates.

  6. Surface Tension and Critical Supersaturations for Mixed Aerosol Particles Composed of Inorganic and Organic Compounds of Atmospheric Relevance

    NASA Astrophysics Data System (ADS)

    Zamora, I. R.; Jacobson, M. Z.

    2012-12-01

    The interaction between water vapor and aerosol particles in the atmosphere has implications on important processes. Among these are cloud droplet formation and growth, which impact cloud properties and therefore have an indirect effect on climate. A significant fraction of the dry submicron mass of atmospheric aerosols is composed of water-soluble organic carbon (WSOC). Although the WSOC fraction contains a large amount of compounds, most yet unidentified, it can be partitioned into three main categories in order to use a set of model substances to reproduce its behavior. In this study, we chose levoglucosan, succinic acid and Nordic Reference fulvic acid (NRFA) to represent the WSOC categories of neutral compounds, mono-/di-carboxylic acids, and polycarboxylic acids, respectively. We measured the surface tension of aqueous pure NRFA and of five of its mixtures at 298 K using the Wilhemy plate method. Langmuir adsorption parameters for the organic mixtures were extracted by fitting the surface tension measurements and corresponding solute concentrations to the Szyszkowski-Langmuir equation. The measured surface tension as a function of aqueous NRFA concentration was identical to that of Suwannee River (SR) and Waskish Peat fulvic acids below 0.02 g/L but up to 12% and 15% higher, respectively, at higher concentrations. Similar to previous findings by Aumann et al. (2010) with SRFA, the surface tension of a NRFA/inorganic salt solution was mainly controlled by the organic compound even when the salt comprised 75% of the added solute mass. This effect was observed for mixtures of NRFA with both sodium chloride and ammonium sulfate salts up to 5 g/L of NRFA. From 5 g/L to about 50 g/L of NRFA, the surface tension for both NRFA/salt mixtures stopped decreasing, remained constant at 52-53 mN/m and then started slowly increasing indicating that the salt component might start dominating at higher concentrations. For a solution of 25% NRFA / 75% levoglucosan, the surface tension lowering with increasing concentration was very similar to that of pure aqueous NRFA even to the maximum measured concentration of 50 g/L of NRFA. However, the surface tension of the NRFA/saccharide mixture exhibited a more linear decrease when plotted against ln(NRFA concentration) in the 0.1 to 50 g/L range. We also measured the surface tension of two additional mixtures based on chemical composition data for different aerosol types. The measured surface tension for the solution representing organic aerosols (40% NRFA / 40% succinic acid / 20% levoglucosan) was bounded by that of pure NRFA and the NRFA/levoglucosan mixture up to a concentration of ~28 g/L of NRFA, where it remained constant at around 46.6 mN/m until 80 g/L of NRFA. The solution representing biomass burning aerosols (25% NRFA/ 27% succinic acid / 18% levoglucosan / 30% ammonium sulfate) had a similar surface tension to pure NRFA up to a concentration of ~5 g/L of NRFA, from where the surface tension drop continued between that of pure NRFA and the NRFA/salt mixtures. Critical supersaturations as a function of dry particle diameter were estimated by using measured water activity as a function of concentration and surface tension data to calculate the maximum of each Köhler curve for the mixtures studied.

  7. The role of long-range transport and domestic emissions in determining atmospheric secondary inorganic particle concentrations across the UK

    NASA Astrophysics Data System (ADS)

    Vieno, M.; Heal, M. R.; Hallsworth, S.; Famulari, D.; Doherty, R. M.; Dore, A. J.; Tang, Y. S.; Braban, C. F.; Leaver, D.; Sutton, M. A.; Reis, S.

    2013-12-01

    Surface concentrations of secondary inorganic particle components over the UK have been analysed for 2001-2010 using the EMEP4UK regional atmospheric chemistry transport model. In early 2003 an episode of substantially elevated surface concentrations of ammonium nitrate was measured across the UK by the AGANET network. The EMEP4UK model was able accurately to represent both the long-term decadal surface concentrations and the episode in 2003. The latter was identified as consisting of three separate episodes, each of less than 1 month duration, in February, March and April. The primary cause of the elevated nitrate levels across the UK was meteorological, a persistent high pressure system, but whose varying location impacted the relative importance of transboundary vs. domestic emissions. Whilst long-range transport dominated the elevated nitrate in February, in contrast it was domestic emissions that mainly contributed to the March episode, and for the April episode both domestic emissions and long-range transport contributed. A prolonged episode such as the one in early 2003 can have substantial impact on annual average concentrations. The episode led to annual concentration differences at the regional scale of similar magnitude to those driven by long-term changes in precursor emissions over the full decade investigated here. The results demonstrate that a substantial part of the UK, particularly the south and south-east, may be close to or actually exceeding annual mean limit values because of import of inorganic aerosol components from continental Europe under specific conditions. The results reinforce the importance of employing multiple year simulations in the assessment of emissions reduction scenarios on PM concentrations and the need for international agreements to address the transboundary component of air pollution.

  8. Size-distributed metallic elements in submicronic and ultrafine atmospheric particles from urban and industrial areas in northern France

    NASA Astrophysics Data System (ADS)

    Mbengue, Saliou; Alleman, Laurent Y.; Flament, Pascal

    2014-01-01

    To determine the size distribution of potentially toxic trace metals (TM) in atmospheric particulate matter (PM), sampling experiments were performed in the urban-industrial area of Dunkirk (North of France) during winter 2012. Total mass concentrations are in accordance with typical values obtained at European urban background sites but lower than the concentrations reported for some Asian industrial countries. Considering the local wind directions, mass concentrations are higher downwind of urban influences than downwind of industrial emissions. The mean PM10 mass concentration (25-30 ?g/m3) is less than the European Union and US EPA limit values (40-50 ?g/m3) but greater than the WHO guidelines (20 ?g/m3). The calculated TM crustal enrichment factors (EFCrust) suggest the anthropogenic origins of most of the studied TM (Sb, Cd, As, Mo, Pb, Zn, Cu, Ni, Cr, Mn and V). The highest TM concentrations were obtained for Zn and Mn (> 50 ng/m3) under industrial influence, but the finest particle (< 0.29 ?m) concentrations were higher for the urban sector than for the industrial sector. This enrichment may be attributed to local urban traffic. In contrast, trace metals are more abundant in the coarser fraction (> 0.29 ?m) downwind of industrial emissions. Moreover, mechanical operations associated with industrial processes (excavating, crushing, and sintering), as well as the resuspension of industrial soils, likely represent some significant TM source-terms in the supermicronic fraction. The EFCrust comparison between the two prevailing sectors demonstrates the importance of steelworks and smelting emissions in the abundance of some TM (As, Cd, Fe, Mn, Mo, Pb, Rb and Zn). In contrast, the Cr and Co concentrations seem to be more related to coal combustion emissions, Cu and Sb to automotive traffic, and V, La and Ni to petrochemical activities.

  9. Encapsulation of particle ensembles in graphene nanosacks as a new route to multifunctional materials.

    PubMed

    Chen, Yantao; Guo, Fei; Qiu, Yang; Hu, Hiroe; Kulaots, Indrek; Walsh, Edward; Hurt, Robert H

    2013-05-28

    Hybrid nanoparticles with multiple functions are of great interest in biomedical diagnostics, therapies, and theranostics but typically require complex multistep chemical synthesis. Here we demonstrate a general physical method to create multifunctional hybrid materials through aerosol-phase graphene encapsulation of ensembles of simple unifunctional nanoparticles. We first develop a general theory of the aerosol encapsulation process based on colloidal interactions within drying microdroplets. We demonstrate that a wide range of cargo particle types can be encapsulated, and that high pH is a favorable operating regime that promotes colloidal stability and limits nanoparticle dissolution. The cargo-filled graphene nanosacks are then shown to be open structures that rapidly release soluble salt cargoes when reintroduced into water, but can be partially sealed by addition of a polymeric filler to achieve slow release profiles of interest in controlled release or theranostic applications. Finally, we demonstrate an example of multifunctional material by fabricating graphene/Au/Fe3O4 hybrids that are magnetically responsive and show excellent contrast enhancement as multimodal bioimaging probes in both magnetic resonance imaging and X-ray computed tomography in full-scale clinical instruments. PMID:23560523

  10. Raman diagnostic of the reactivity between ZnSO4 and CaCO3 particles in humid air relevant to heterogeneous zinc chemistry in atmosphere

    NASA Astrophysics Data System (ADS)

    Falgayrac, Guillaume; Sobanska, Sophie; Brémard, Claude

    2014-03-01

    Laboratory experiments using Raman imaging demonstrated the behaviour of ZnSO4·7H2O (goslarite) microparticles in contact with a {101bar4} CaCO3 (calcite) surface under three different experimental conditions representative of remote atmosphere. Contact between the ZnSO4·7H2O particles and the CaCO3 surface in humid air (RH ?40-80%) did not induce any deliquescence and chemical phenomena. In contrast, condensation of a water drop at the ZnSO4·7H2O-CaCO3 interface caused free dissolution of the ZnSO4·7H2O particle and rapid precipitation of Zn4SO4(OH)6 onto the CaCO3 surface. This coating inhibited the surface reaction and subsequent drying resulted in the deposition of residual ZnSO4·7H2O, then ZnSO4·H2O (gunningite) and CaSO4·2H2O (gypsum) superimposed onto the Zn4SO4(OH)6 layer. The deposition of ZnSO4·7H2O particles in a water drop, previously in contact with a CaCO3 particle for a long time, resulted in the coprecipitation of Zn4SO4(OH)6 and Zn5(CO3)2(OH)6 (hydrozincite). Subsequent drying caused the deposition of residual ZnSO4·7H2O, ZnSO4·H2O and CaSO4·2H2O as small particles. These results indicated the possible fates of ZnSO4 particles in a humid atmosphere, when externally mixed with CaCO3 mineral dust after atmospheric events such as aggregation, water condensation and evaporation. This study indicated the fundamental role of water that typically existed on the surface of aerosol particles in the troposphere. These heterogeneous chemical processes have substantial consequences on particle size and solubility, and thus on bioavailability and toxicity of metal-rich particles.

  11. Interaction of Plutonium with Diverse Materials in Moist Air and Nitrogen-Argon Atmospheres at Room Temperature

    SciTech Connect

    John M. Haschke; Raymond J. Martinez; Robert E. Pruner II; Barbara Martinez; Thomas H. Allen

    2001-04-01

    Chemical and radiolytic interactions of weapons-grade plutonium with metallic, inorganic, and hydrogenous materials in atmospheres containing moist air-argon mixtures have been characterized at room temperature from pressure-volume-temperature and mass spectrometric measurements of the gas phase. A reaction sequence controlled by kinetics and gas-phase composition is defined by correlating observed and known reaction rates. In all cases, O{sub 2} is eliminated first by the water-catalyzed Pu + O{sub 2} reaction and H{sub 2}O is then consumed by the Pu + H{sub 2}O reaction, producing a gas mixture of N{sub 2}, argon, and H{sub 2}. Hydrogen formed by the reaction of water and concurrent radiolysis of hydrogenous materials either reacts to form PuH{sub 2} or accumulates in the system. Accumulation of H{sub 2} is correlated with the presence of hydrogenous materials in liquid and volatile forms that are readily distributed over the plutonium surface. Areal rates of radiolytic H{sub 2} generation are determined and applied in showing that modest extents of H{sub 2} production are expected for hydrogenous solids if the contact area with plutonium is limited. The unpredictable nature of complex chemical systems is demonstrated by occurrence of the chloride-catalyzed Pu + H{sub 2}O reaction in some tests and hydride-catalyzed nitriding in another.

  12. Lanthanum hexaaluminate—a new material for atmospheric plasma spraying of advanced thermal barrier coatings

    Microsoft Academic Search

    C. Friedrich; R. Gadow; T. Schirmer

    2001-01-01

    One of the main application fields of the thermal spraying process is thermal barrier coatings (TBCs). Today, partially stabilized\\u000a zirconia (YSZ or MSZ) is mainly used as a TBC material. At temperatures above 1000 ?C, zirconia layers age distinctively,\\u000a including phenomena shrinkage and microcrack formation. Therefore, there is a considerable interest in TBCs for higher temperature\\u000a applications. In this paper,

  13. Study of the Durability of Doped Lanthanum Manganite and Cobaltite Cathode Materials under “Real World” Air Exposure Atmospheres

    SciTech Connect

    Singh, Prabhakar; Mahapatra, Manoj; Ramprasad, Rampi; Minh, Nguyen; Misture, Scott

    2014-11-30

    The overall objective of the program is to develop and validate mechanisms responsible for the overall structural and chemical degradation of lanthanum manganite as well as lanthanum ferrite cobaltite based cathode when exposed to “real world” air atmosphere exposure conditions during SOFC systems operation. Of particular interest are the evaluation and analysis of degradation phenomena related to and responsible for (a) products formation and interactions with air contaminants, (b) dopant segregation and oxide exolution at free surfaces, (c) cation interdiffusion and reaction products formation at the buried interfaces, (d) interface morphology changes, lattice transformation and the development of interfacial porosity and (e) micro-cracking and delamination from the stack repeat units. Reaction processes have been studied using electrochemical and high temperature materials compatibility tests followed by structural and chemical characterization. Degradation hypothesis has been proposed and validated through further experimentation and computational simulation.

  14. Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers

    NASA Astrophysics Data System (ADS)

    Akyildiz, Halil I.; Mousa, Moataz Bellah M.; Jur, Jesse S.

    2015-01-01

    Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI process temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-Ox product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.

  15. Europa's Atmosphere: Production & Loss

    NASA Astrophysics Data System (ADS)

    Bagenal, F.; Cassidy, T. A.; Dols, V.; Crary, F. J.

    2013-12-01

    Europa is embedded not only in the ionized material of the Io plasma torus, but is also surrounded by the material (both ionized and neutral) produced by the interaction of this plasma with the moon's surface and atmosphere. Moreover, there are energetic ions and electrons that diffuse inwards from the outer magnetosphere and interact with the moon and surrounding neutral clouds. The multiple components of Europa's environment are thought to vary on timescales of hours to weeks and to be strongly coupled. Europa's O2 atmosphere is created by ion bombardment of the surface. Earlier studies assumed that the energetic (10s keV) ions were responsible (see review in Smyth and Marconi, 2006). New research (Cassidy et al. 2013) suggests that the 'thermal' ion population of the Io plasma torus produces most of Europa's O2. But this cooler population is easily diverted by currents induced in Europa's ionosphere and prevented from reaching the surface. This feedback has not been adequately explored. Modelers have historically focused on a single piece of the puzzle; plasma modelers assume a static atmosphere and atmosphere modelers assume static plasma. We are now in a position to consider these new sources of atmosphere and determine how the observed system comes about as well as quantify the timescales and causes of its evolution. This begs the question is Europa's atmosphere-magnetosphere interaction self-regulating? We are specifically interested in how the system responds to changes - for example, how does Europa's atmosphere change when the inflowing plasma flux increases or decreases? What is the corresponding change in the electrodynamics and diversion of plasma flow around Europa? How much and on what time scale does the extended neutral cloud respond? And what are the consequences for the influx of energetic particles? We model this coupled system to address how each component responds to changes in the other components.

  16. Europa's Atmosphere: Production & Loss

    NASA Astrophysics Data System (ADS)

    Bagenal, Fran; Cassidy, T.; Dols, V.; Crary, F.

    2013-10-01

    Europa is embedded not only in the ionized material of the Io plasma torus, but is also surrounded by the material (both ionized and neutral) produced by the interaction of this plasma with the moon’s surface and atmosphere - as illustrated in the schematic below. Moreover, there are energetic ions and electrons that diffuse inwards from the outer magnetosphere and interact with the moon and surrounding neutral clouds. The multiple components of Europa’s environment are thought to vary on timescales of hours to weeks and to be strongly coupled. Europa’s O2 atmosphere is created by ion bombardment of the surface. Earlier studies assumed that the energetic (10s keV) ions were responsible (see review in Smyth and Marconi, 2006). New research (Cassidy et al. 2013) suggests that the “thermal” ion population of the Io plasma torus produces most of Europa’s O2. But this cooler population is easily diverted by currents induced in Europa’s ionosphere and prevented from reaching the surface. This feedback has not been adequately explored. Modelers have historically focused on a single piece of the puzzle; plasma modelers assume a static atmosphere and atmosphere modelers assume static plasma. We are now in a position to consider these new sources of atmosphere and determine how the observed system comes about as well as quantify the timescales and causes of its evolution. This begs the question is Europa’s atmosphere-magnetosphere interaction self-regulating? We are specifically interested in how the system responds to changes - for example, how does Europa’s atmosphere change when the inflowing plasma flux increases or decreases? What is the corresponding change in the electrodynamics and diversion of plasma flow around Europa? How much and on what time scale does the extended neutral cloud respond? And what are the consequences for the influx of energetic particles? We model this coupled system to address how each component responds to changes in the other components.

  17. Extension of a Current Continuum-Level Material Model for Soil into the Low-Density Discrete-Particle Regime

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Yavari, R.; Snipes, J. S.; Ramaswami, S.

    2013-05-01

    In this article, an attempt is made to construct a soil-material model which can be used over a wide range of soil densities. To construct such a model, an existing purely continuum-type soil material model (used in the high-density regime), within which the granular structure of the soil is neglected, is combined with an existing discrete-type soil material model (used in the low-density regime) within which soil is treated as an assembly of interacting particles. In order to enable it to be used in conventional transient, nonlinear dynamics, and finite element analyses, the new soil material model is cast using a continuum-type framework. Thus, while in the low-density regime soil behavior is fully dominated by the discrete-type soil-material model, soil has been treated as a continuum constituent properties of which are governed by particle geometrical parameters and particle-particle interaction laws. To demonstrate the utility and fidelity of the new soil material model, a series of uniaxial strain computational tests involving rectangular, parallelepiped-shaped soil-slug normal impact onto a rigid, fixed, flat surface is carried out. While these tests are of a one-dimensional character, they are generally considered as being representative of the loading and deformation histories experienced by mine-blast-ejected soil during its impact with the target structure. The results obtained using the newly proposed soil material model, in the low-density regime, are found to be fully consistent with their discrete-particle modeling and simulation counterparts, suggesting that the new model can be used in transient nonlinear dynamics, finite element simulations involving low-density soil.

  18. Volatile production in nonice materials on Solar System bodies with tenuous atmospheres by ion bombardment - Laboratory results

    NASA Astrophysics Data System (ADS)

    Hibbitts, C. A.; Thevuthasan, S.; Shutthanandan, V.; Orlando, T.; Hansen, G. B.; McCord, T. B.

    2003-05-01

    Volatiles, inferred to be trapped in nonice materials, have been discovered on the Jovian satellites and in IDPs [McCord et al., 1998; Hibbitts et al., 2000; Flynn et al., 2002]. In general, these types of volatiles may be produced through high-energy ion bombardment of Solar System bodies that have tenuous atmospheres, from the Moon to the Saturnian satellites and beyond. The surfaces of these bodies are continually bombarded by a combination of cosmic, solar, and planetary magnetospheric radiation including UV, keV protons and Helium nuclei, and more massive keV to MeV ions. The Moon's surface contains Fe-oxides that may release water products under bombardment by solar wind protons. Many classes of asteroids and the outer planets' satellites appear to contain clays or other OH-bearing materials that could release water-products as well under bombardment. Also, organic material, likely present on surfaces other than the Moon, may participate in bombardment reactions to form carbon monoxide or dioxide. Results from our laboratory experiments conducted at the Environmental Molecular Sciences Laboratory (EMSL) accelerator facility, Pacific Northwest National Laboratory (PNNL) show that volatiles are produced during MeV ion irradiation of these types of materials. We bombarded clays, oxyhydroxides, ilmenite, and carbon-doped samples with MeV hydrogen, deuterium, oxygen, and sulfur ions at current densities of 100 to 1000 namps ( 1E12 to 1E13 ions/cm2/sec) over several minutes. Ohmic heating and outgassing of trapped atmospheric gases was minimal at the lower flux levels. Most of the irradiation effects are non-thermal and are due to ionization and momentum transfer processes. Proton or deuteron bombardment of ilmenite produces water-related molecules that are quickly released into the vacuum chamber and detected by mass spectrometry. The bombardment of carbon-doped clays appears to produce CO. This process occurs independently of any reduction of FeO involved in micrometoroid impacts [Tsay et al., 1971].

  19. An In-situ materials analysis particle probe (MAPP) diagnostic to study particle density control and hydrogenic fuel retention in NSTX

    SciTech Connect

    Allain, Jean Paul [Purdue Univ., West Lafayette, IN (United States)

    2014-09-05

    A new materials analysis particle probe (MAPP) was designed, constructed and tested to develop understanding of particle control and hydrogenic fuel retention in lithium-based plasma-facing surfaces in NSTX. The novel feature of MAPP is an in-situ tool to probe the divertor NSTX floor during LLD and lithium-coating shots with subsequent transport to a post-exposure in-vacuo surface analysis chamber to measure D retention. In addition, the implications of a lithiated graphite-dominated plasma-surface environment in NSTX on LLD performance, operation and ultimately hydrogenic pumping and particle control capability are investigated in this proposal. MAPP will be an invaluable tool for erosion/redeposition simulation code validation.

  20. Atmospheric Deposition

    Microsoft Academic Search

    Kathleen C. Weathers; Alexandra G. Ponette-González

    \\u000a Atmospheric deposition plays a key role in the biogeochemistry of temperate, tropical, and boreal forests. Many essential\\u000a macro- and micronutrients as well as pollutants are delivered from the atmosphere to forest ecosystems: (1) dissolved in rain\\u000a and snow (wet deposition); (2) directly as particles and gases (dry deposition); and (3) dissolved in cloud droplets (cloud,\\u000a occult, or fog deposition, hereafter

  1. Analysis of mass loss of a coal particle during the course of burning in a flow of inert material

    SciTech Connect

    Pelka, Piotr [Czestochowa University of Technology, Department of Boilers and Thermodynamics, Armii Krajowej 19c, Czestochowa, Silesia 42-200 (Poland)

    2009-08-15

    This paper is an attempt to explain the role of erosion during the process of coal combustion in a circulating fluidized bed. Different kinds of carbon deposits found in Poland, both bituminous as well as lignite with the particle of 10 mm in diameter were the subject of the research. According to many publications it is well known that erosion plays a significant role in coal combustion, by changing its mechanism as well as generating an additional mass loss of the mother particle. The purpose of this research was to determine the influence of an inert material on an erosive mass loss of a single coal particle burning in a two-phase flow. The determination of the influence of a coal type, the rate of flow of inert material and the temperature inside the furnace on the erosive mass loss of burning coal particle was also taken into consideration. The results obtained indicate that the velocity of the erosive mass loss depends on the chemical composition and petrographic structure of burning coal. The mechanical interaction of inert and burning coal particles leads to the shortening of the period of overall mass loss of the coal particle by even two times. The increase in the rate of flow of the inert material intensifies the generation of mass loss by up to 100%. The drop in temperature which slows down the combustion process, decreases the mass loss of the coal particle as the result of mechanical interaction of the inert material. As was observed, the process of percolation plays a significant role by weakening the surface of the burning coal. (author)

  2. Tunable diode laser IR spectrometer for in situ measurements of the gas phase composition and particle size distribution of Titan's atmosphere

    NASA Technical Reports Server (NTRS)

    Webster, Christopher R.; Sander, Stanley P.; Beer, Reinhard; May, Randy D.; Knollenberg, Robert G.

    1990-01-01

    A new instrument, the Probe Infrared Laser Spectrometer (PIRLS), is described for in situ sensing of the gas composition and particle size distribution of Titan's atmosphere on the NASA/ESA Cassini mission. For gas composition measurements, several narrow-band (0.0001/cm) tunable lead-salt diode lasers operating near 80 K at selected mid-IR wavelengths are directed over a path length defined by a small reflector extending over the edge of the probe spacecraft platform; volume mixing ratios of 10 to the -9th should be measurable for several species of interest. A cloud-particle-size spectrometer using a diode laser source at 780 nm shares the optical path and deployed reflector; a combination of imaging and light scattering techniques is used to determine sizes of haze and cloud particles and their number density as a function of altitude.

  3. Parameterization of Shortwave Cloud Optical Properties for a Mixture of Ice Particle Habits for use in Atmospheric Models

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Lee, Kyu-Tae; Yang, Ping; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Based on the single-scattering optical properties pre-computed with an improved geometric optics method, the bulk absorption coefficient, single-scattering albedo, and asymmetry factor of ice particles have been parameterized as a function of the effective particle size of a mixture of ice habits, the ice water amount, and spectral band. The parameterization has been applied to computing fluxes for sample clouds with various particle size distributions and assumed mixtures of particle habits. It is found that flux calculations are not overly sensitive to the assumed particle habits if the definition of the effective particle size is consistent with the particle habits that the parameterization is based. Otherwise, the error in the flux calculations could reach a magnitude unacceptable for climate studies. Different from many previous studies, the parameterization requires only an effective particle size representing all ice habits in a cloud layer, but not the effective size of individual ice habits.

  4. Scattering and absorption coefficients vs. Chemical composition of fine atmospheric aerosol particles under regional conditions in Hungary

    Microsoft Academic Search

    E Mészáros; A Molnár; J Ogren

    1998-01-01

    The light scattering and absorption coefficients of aerosol particles with a dry diameter below 1?m were recorded in the country air of Hungary. Concentrations of different inorganic and organic ions were measured in parallel to estimate the nature of particles causing light scattering. The sample air was heated gently to maintain a relative humidity of 30% and coarse particles were

  5. Effect of packing solid material on characteristics of helium dielectric barrier discharge at atmospheric pressure

    SciTech Connect

    Tu, X.; Corthals, S.; Sels, B. F. [Center for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Heverlee (Belgium); Verheyde, B.; Paulussen, S. [Materials Technology, Vlaamse Instelling voor Technologisch Onderzoek (VITO), Mol (Belgium)

    2011-08-15

    The influence of a solid material (e.g., Al{sub 2}O{sub 3}) on the physical characteristics of helium dielectric barrier discharge (DBD) has been investigated in a cylindrical plasma reactor. The helium DBD with the solid packing shows a multiple current-peak effect, which can be ascribed to the enhancement of charge density due to charge deposition on the Al{sub 2}O{sub 3} pellet surface. The combination of plasma and the solid increases both the peak-to-peak voltage and breakdown voltage of the discharge at a fixed input power but decreases the discharge temperature. It is also found that the presence of the solid has a weak effect on the electron temperature and density in the discharge.

  6. Caramel popcorn shaped silicon particle with carbon coating as a high performance anode material for Li-ion batteries.

    PubMed

    He, Meinan; Sa, Qina; Liu, Gao; Wang, Yan

    2013-11-13

    Silicon is a very promising anode material for lithium ion batteries. It has a 4200 mAh/g theoretical capacity, which is ten times higher than that of commercial graphite anodes. However, when lithium ions diffuse to Si anodes, the volume of Si will expand to almost 400% of its initial size and lead to the crack of Si. Such a huge volume change and crack cause significant capacity loss. Meanwhile, with the crack of Si particles, the conductivity between the electrode and the current collector drops. Moreover, the solid electrolyte interphase (SEI), which is generated during the cycling, reduces the discharge capacity. These issues must be addressed for widespread application of this material. In this work, caramel popcorn shaped porous silicon particles with carbon coating are fabricated by a set of simple chemical methods as active anode material. Si particles are etched to form a porous structure. The pores in Si provide space for the volume expansion and liquid electrolyte diffusion. A layer of amorphous carbon is formed inside the pores, which gives an excellent isolation between the Si particle and electrolyte, so that the formation of the SEI layer is stabilized. Meanwhile, this novel structure enhances the mechanical properties of the Si particles, and the crack phenomenon caused by the volume change is significantly restrained. Therefore, an excellent cycle life under a high rate for the novel Si electrode is achieved. PMID:24111737

  7. Facile preparation of core@shell and concentration-gradient spinel particles for Li-ion battery cathode materials

    NASA Astrophysics Data System (ADS)

    Kozawa, Takahiro; Naito, Makio

    2015-02-01

    Core@shell and concentration-gradient particles have attracted much attention as improved cathodes for Li-ion batteries (LIBs). However, most of their preparation routes have employed a precisely-controlled co-precipitation method. Here, we report a facile preparation route of core@shell and concentration-gradient spinel particles by dry powder processing. The core@shell particles composed of the MnO2 core and the Li(Ni,Mn)2O4 spinel shell are prepared by mechanical treatment using an attrition-type mill, whereas the concentration-gradient spinel particles with an average composition of LiNi0.32Mn1.68O4 are produced by calcination of their core@shell particles as a precursor. The concentration-gradient LiNi0.32Mn1.68O4 spinel cathode exhibits the high discharge capacity of 135.3 mA h g?1, the wide-range plateau at a high voltage of 4.7 V and the cyclability with a capacity retention of 99.4% after 20 cycles. Thus, the facile preparation route of the core@shell and concentration-gradient particles may provide a new opportunity for the discovery and investigation of functional materials as well as for the cathode materials for LIBs.

  8. On panspermia and the survivability of micrometre-sized meteoroids within the Earth's atmosphere

    Microsoft Academic Search

    S. G. Coulson

    2004-01-01

    A prediction of panspermia is that organic material should be abundant throughout the universe. The recovery of micrometre-sized biotic particles at altitudes of around 40 km above the Earth is a key indicator of the validity of panspermia. A common criticism of experiments to capture atmospheric particles is that the particles could have originated from the Earth. Theoretical models of

  9. PARTICLE SIZE SEGREGATION DURING HAND PACKING OF COARSE GRANULAR MATERIALS AND IMPACTS ON LOCAL PORE-SCALE STRUCTURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soils and sediments consist of granular particles with an intricate network of pores in between. The structure and orientation of these pores will determine how the material transports fluids and contaminants. A common practice in soil science to simplify experiments and to achieve a homogeneous med...

  10. Wear Properties of Intermetallic Compound Reinforced Functionally Graded Materials Fabricated by Centrifugal Solid-particle and In-Situ Methods

    NASA Astrophysics Data System (ADS)

    Watanabe, Yoshimi; Sato, Hisashi; Fukui, Yasuyoshi

    One of the functionally graded material (FGM) fabrication methods is a centrifugal method, which is an application of the centrifugal casting technique. The centrifugal force applied to a homogeneous molten composite assists the formation of the desired gradation. In this paper, the wear properties of two kinds of Al base FGMs, namely Al-Al3Ti FGM and Al-Al3Ni FGM, are reported. The former and the latter hold the oriented intermetallic compound platelets and the particle size gradient, respectively. Here, volume fraction, size, shape and orientation of the reinforcements in the composite play an important role in improving the mechanical properties of the materials, whereby FGMs with oriented platelets or particle size gradient may have special mechanical properties such as increased wear resistance. Based on the experimental results, the origin of anisotropic wear resistance and the effect of particle size on the wear properties are discussed.

  11. Dependence of demagnetizing fields in Fe-based composite materials on magnetic particle size and the resin content

    NASA Astrophysics Data System (ADS)

    Kollár, Peter; Bir?áková, Zuzana; Vojtek, Vladimír; Füzer, Ján; Bureš, Radovan; Fáberová, Mária

    2015-08-01

    Demagnetizing fields are in general produced by the volume and surface magnetic poles. The structure of soft magnetic composite materials, where the ferromagnetic particles are insulated from each other, causes the formation of demagnetizing fields produced by the particle surfaces. These fields depend on the amount of insulation and on the shapes, clustering and distribution of ferromagnetic particles. In this work the demagnetizing fields in iron-phenolphormaldehyde resin composite samples were investigated experimentally using the method for determining the demagnetization factor from the anhysteretic magnetization curve measurement. The initial magnetization curves were calculated for an ideal composite with 100% filler content using the values of the demagnetization factor. The results on the "ideal" permeability show differences between the samples with different resin content for each granulometric class, which tells about the internal stresses introduced into ferromagnetic material during the compaction process.

  12. Fundamentals of Atmospheric Radiation

    NASA Astrophysics Data System (ADS)

    Bohren, Craig F.; Clothiaux, Eugene E.

    2006-02-01

    This textbook fills a gap in the literature for teaching material suitable for students of atmospheric science and courses on atmospheric radiation. It covers the fundamentals of emission, absorption, and scattering of electromagnetic radiation from ultraviolet to infrared and beyond. Much of the book applies to planetary atmosphere. The authors are physicists and teach at the largest meteorology department of the US at Penn State. Craig T. Bohren has taught the atmospheric radiation course there for the past 20 years with no book. Eugene Clothiaux has taken over and added to the course notes. Problems given in the text come from students, colleagues, and correspondents. The design of the figures especially for this book is meant to ease comprehension. Discussions have a graded approach with a thorough treatment of subjects, such as single scattering by particles, at different levels of complexity. The discussion of the multiple scattering theory begins with piles of plates. This simple theory introduces concepts in more advanced theories, i.e. optical thickness, single-scattering albedo, asymmetry parameter. The more complicated theory, the two-stream theory, then takes the reader beyond the pile-of-plates theory. Ideal for advanced undergraduate and graduate students of atmospheric science.

  13. Influence of material properties on the agglomeration of water-soluble amorphous particles

    Microsoft Academic Search

    Stefan Palzer

    2009-01-01

    The viscosity and elasticity of particles influence their agglomeration behaviour. Such mechanical particle properties are determined by the supra-molecular and microscopic structure of the particles and process conditions such as temperature, humidity and strain rate or frequency.Most food powders are composed of amorphous water soluble substances. Accordingly spray dried dextrose syrup is used as a model substance for the current

  14. Influence of the Salting-out Effect of Ammonium Sulfate on the Gas-Particle Partitioning of Organic Compounds in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Wang, C.; Lei, Y. D.; Endo, S.; Wania, F.

    2014-12-01

    As one of the major salts in the atmosphere, ammonium sulfate ((NH4)2SO4) influences significantly the partitioning of organic compounds into atmospheric aqueous phases. This salting out effect has important implications regarding the reactivity, transport and fate of organic compounds in atmospheric waters, particularly in aerosol particles because of the relatively large amount of salts present. However, very few studies have quantified the salting out effect of (NH4)2SO4. For the first time, we measured salting-out coefficients (or Setschenow constants) (KS [M-1]) for a large and diverse group of organic compounds in (NH4)2SO4 solutions at a wide range of salt concentrations, providing a reliable database for model development. KS values for (NH4)2SO4 are correlated with and always higher than KS for sodium chloride (NaCl), suggesting a higher salting-out effect of (NH4)2SO4. Three modeling approaches: a poly-parameter linear free energy relationship (pp-LFER), the quantum-chemical COSMOtherm software and the group contribution method AIMOFAC, were calibrated and evaluated in terms of their capability to predict KS. Relative merits of the prediction methods were identified. These models can be applied to estimate Setschenow constants for atmospherically relevant compounds involved in secondary organic aerosol formation based on chemical structure alone.

  15. PAVAN: an atmospheric-dispersion program for evaluating design-basis accidental releases of radioactive materials from nuclear power stations

    SciTech Connect

    Bander, T.J.

    1982-11-01

    This report provides a user's guide for the NRC computer program, PAVAN, which is a program used by the US Nuclear Regulatory Commission to estimate downwind ground-level air concentrations for potential accidental releases of radioactive material from nuclear facilities. Such an assessment is required by 10 CFR Part 100 and 10 CFR Part 50. The program implements the guidance provided in Regulatory Guide 1.145, Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants. Using joint frequency distributions of wind direction and wind speed by atmospheric stability, the program provides relative air concentration (X/Q) values as functions of direction for various time periods at the exclusion area boundary (EAB) and the outer boundary of the low population zone (LPZ). Calculations of X/Q values can be made for assumed ground-level releases (e.g., through building penetrations and vents) or elevated releases from free-standing stacks. Various options may be selected by the user. They can account for variation in the location of release points, additional plume dispersion due to building wakes, plume meander under low wind speed conditions, and adjustments to consider non-straight trajectories. It computes an effective plume height using the physical release height which can be reduced by inputted terrain features. It cannot handle multiple emission sources. A description of the main program and all subroutines is provided. Also included as appendices are a complete listing of the program and two test cases with the required data inputs and the resulting program outputs.

  16. Surface modification due to atmospheric pressure plasma treatment during film growth of silicon dioxide like and amorphous hydrogenated carbon material

    NASA Astrophysics Data System (ADS)

    Ruegner, Katja; Reuter, Ruediger; von Keudell, Achim; Benedikt, Jan

    2014-10-01

    Plasma deposition of silicon dioxide (SiO2) or amorphous hydrogenated carbon (a-C:H) at atmospheric pressure is a promising tool for industrial applications. SiO2 is used as scratch resistant layers, as protection against corrosion or as gas diffusion barrier layers. a-C:H is of special interest due to its optical, electrical, biocompatible and mechanical properties, which are tunable, depending on the bonding state of carbon. Besides the deposition of material, atmospheric pressure plasma jets (APPJ) can be used to modify the surface of the deposited films during their growth. Deposition and the treatment are realized in the same chamber, were both jets face a rotating substrate. Therefore, deposition and treatment of the same trace can be performed in an alternating manner. Further, in-situ FTIR is applied. For the deposition an APPJ with two parallel electrodes is used, operating with either He/HMDSO in the case of SiO2 deposition or He/C2H2 in the case of a-C:H deposition. For the treatment either the APPJ or a coaxial jet with different gas mixtures is used. For the deposition of SiO2-like films the treatment with a He/O2, a He/N2, and an Ar plasma during the film growth have shown significant changes in the film structure. The influence of treatments on a-C:H film is currently under investigation. The project is supported by the German Research Foundation (DFG) in the research group FOR 1123.

  17. Characterization of Damage to Bacteria and Bio-macromolecules Caused by (V)UV Radiation and Particles Generated by a Microscale Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    Lackmann, Jan-Wilm; Schneider, Simon; Narberhaus, Franz; Benedikt, Jan; Bandow, Julia E.

    Atmospheric pressure plasma jets effectively inactivate bacteria on ­surfaces including infected tissues. This is due to the combined effects of (V)UV radiation, reactive oxygen and nitrogen species, ions, and high electric fields. A well-characterized microscale atmospheric pressure plasma jet (?-APPJ) operated with He/O2 gas mixture has been modified so that (V)UV radiation and heavy reactive particles (mainly O3 molecules and O atoms) emitted from the plasma source can be separated effectively. The separation is achieved by an additional lateral He flow, which diverts the heavy particles from the jet axis. The new jet geometry is called X-Jet. Separation of different plasma components allows studying their effects on living cells and bio-macromolecules separately. First, the effectiveness of the separation of different plasma components was demonstrated by treatment of monolayers of vegetative Bacillus subtilis cells. To characterize effects on nucleic acids, dried plasmid DNA and total cellular RNA were treated with the separated plasma components. Dried bovine serum albumin was used to study etching effects of (V)UV radiation and heavy particles on proteins. We found that heavy particles emitted from the X-Jet kill vegetative cells more effectively than the (V)UV radiation from this type of plasma source. All bio-macromolecules investigated, DNA, RNA, and proteins, are affected by plasma treatment. DNA exposed to the (V)UV-channel of the jet seems to be prone to thymine dimer formation not only in vitro but also in vivo as indicated by induction of the photolyase in Escherichia coli, while DNA strand breaks occur under both jet channels. Heavy particles seem more effective in degrading RNA and in etching protein in vitro.

  18. Diamond and Related Materials, 2 (1993) 661 666 661 Degenerate four-wave mixing diagnostics of atmospheric pressure

    E-print Network

    Zare, Richard N.

    1993-01-01

    of atmospheric pressure diamond deposition T. G. Owano and C. H. Kruger Iti~'4h7~,mperatureGasdynamies Laboratory of atmospheric pressure diamond synthesis reactors are evaluated. Benefits and disadvantages of optical emission (DFWM), are discussed in terms of their applicability to the harsh environment of atmospheric pressure

  19. Particle scale modelling of the multiphase flow in a dense medium cyclone: Effect of near gravity material

    NASA Astrophysics Data System (ADS)

    Chen, J.; Chu, K. W.; Yu, A. B.; Vince, A.; Barnett, G. D.; Barnett, P. J.

    2013-06-01

    Dense medium cyclone (DMC) is widely used to upgrade the run-of-mine coal in the coal industry. It is known that the amount of near gravity material (NGM) fed into a DMC is an important parameter since it may cause problems such as vortex finder/spigot overloading, surging phenomenon, and system instability. Until now, the underlying mechanism of this phenomenon is not well understood. Here, this phenomenon is studied numerically using a previously developed method of combined computational fluid dynamics and discrete element method (CFD-DEM), facilitated by a "parcel-particle" model to account for fine particles. The simulated results are analyzed for fundamental understanding, in terms of medium and coal flow patterns, particle-fluid, particle-particle and particle-wall interaction forces. It is found that the amount of NGM has a significant effect on the stability inside a DMC. When there are excessive NGM fed into a DMC, the solid concentration below the vortex finder increases drastically, resulting in high local tangential particle-fluid and particleparticle interaction forces. Correspondingly, the pressure drop is high there, and so is the pressure gradient force. This unstable flow structure has been identified as a cause of the vortex finder overloading phenomenon in the DMC operation.

  20. Simulations on the gelling process of particle suspension systems for in-situ preparing porous materials in a capillary

    NASA Astrophysics Data System (ADS)

    Wang, J.; Xu, J. J.; Yang, Y.; Wang, X. J.; Luo, X.; Zhang, L.; Jiang, G.

    2015-10-01

    The gelling process of particle suspension in a capillary which is crucial for in-situ preparing small size foam products has been simulated with an off-lattice diffusion limited cluster aggregation (DLCA) model by the three-dimensional Monte Carlo simulations. The effects of the model parameters, such as the interaction between capillary wall and particles, particle volume fraction, capillary size etc. on the density distribution of the system have been fully explored. And the aggregation kinetics process over a broad range of volume fractions and interactions have also been discussed. The results show that the geometric constraint of capillary can be analogous to a weak repulsive interaction between capillary wall and particles. And we found that as the capillary size or particle volume fraction increase, particle concentration distribution will be more uniform with other parameters constant. Porous network with relatively uniform density distribution can be also obtained through controlling the interaction between capillary wall and particles. In addition, by analyzing the aggregation kinetics process, we found that the attraction of capillary wall dramatically reduces the probability of gelation in the small-scale capillary. The obtained results will be of great importance in controlling the density distribution of porous materials prepared by in-situ methods.

  1. On-line measurement of perchlorate in atmospheric aerosol based on ion chromatograph coupled with particle collector and post-column concentrator.

    PubMed

    Takeuchi, Masaki; Yoshioka, Kaoru; Toyama, Yusuke; Kagami, Ai; Tanaka, Hideji

    2012-08-15

    An automated analysis system has been developed for measuring perchlorate concentration in atmospheric aerosol. The perchlorate in aerosol sample, which has been collected with water mist in a hydrophobic filter/mist chamber based particle collector, is continuously preconcentrated. The matrix ions such as sulfate are subsequently removed from the preconcentrator. The remaining perchlorate is then analyzed on-line with an ion chromatograph in conjunction with a Nafion membrane tube based post-column concentrator. The sensitivity is increased by a factor of 7.7 with the post-column concentration technique. The proposed system has been successfully operated at Tokushima, Japan. The limit of detection is 0.35 ng/m(3) for 3 h sampling cycle. The perchlorate concentration in the atmospheric aerosol averaged 1.01±1.75 ng/m(3) (n=12). PMID:22841118

  2. FEASIBILITY OF MAGNETIC PARTICLE FILMS FOR CURIE TEMPERATURE-CONTROLLED PROCESSING OF COMPOSITE MATERIALS

    EPA Science Inventory

    The feasibility of using magnetic particulate susceptor materials for induction heating during bonding of polymer matrix composite materials is investigated. If properly designed, these systems should rapidly heat to the particulate material Curie temperature and dwell at that te...

  3. Analysis of intact tetraether lipids in archaeal cell material and sediments by high performance liquid chromatography\\/atmospheric pressure chemical ionization mass spectrometry

    Microsoft Academic Search

    J. S. Sinninghe Damsté; E. C. Hopmans; S. Schouten; R. D. Pancost; M. T. J. van der Meer

    2000-01-01

    A method combining normal phase high performance liquid chromatography (HPLC) with positive ion atmospheric pressure chemical ionization mass spectrometry (APCI-MS) was developed for the analysis of intact glycerol dialkyl glycerol tetraethers (GDGTs) in archaeal cell material and sediments. All GDGTs previously reported to occur in the thermophilic archaeon Sulfolobus solfataricus could be identified based on their mass spectra and retention

  4. Occurrence and gas/particle partitioning of short- and medium-chain chlorinated paraffins in the atmosphere of Fildes Peninsula of Antarctica

    NASA Astrophysics Data System (ADS)

    Ma, Xindong; Zhang, Haijun; Zhou, Hongqiang; Na, Guangshui; Wang, Zhen; Chen, Chen; Chen, Jingwen; Chen, Jiping

    2014-06-01

    Chlorinated paraffins (CPs) were measured in air samples at a remote air monitoring site established in Georgia King Island, Fildes Peninsula of Antarctica (Great Wall Station, China) to study the long-range atmospheric transport of these anthropogenic pollutants to the Antarctic. Gas- and particle-phase CPs were collected using polyurethane foam plugs (PUF) and glass fiber filters (GFF) respectively during summertime of 2012. The total atmospheric levels of SCCPs and MCCPs ranged from 9.6 to 20.8 pg m-3 (average: 14.9 pg m-3) and 3.7-5.2 pg m-3 (average: 4.5 pg m-3), respectively. C10 and C11 carbon chain homologues with Cl5 and Cl6 chlorine atoms predominated in SCCP formula groups both in gas- and particle-phase. Significant linear correlation was found between gas/particle partition coefficients (KP) and sub-cooled liquid vapor pressures (pL°) (R2 = 0.437, p < 0.01), as well as KP and octanol-air partition coefficients (KOA) (R2 = 0.442, p < 0.01). Absolute slope values of two regression models (0.31 and 0.39) were less than 0.6 indicating that the way of absorption into organic matter of aerosol played a more important role on atmospheric partitioning and transferring of CPs in remote Antarctic area. Both the Junge-Pankow model and the KOA-based model tended to underestimate the sorption of lower chlorinated CPs and overestimate the sorption of highly chlorinated CPs.

  5. On the dry deposition of submicron particles

    SciTech Connect

    Wesely, M. L.

    1999-10-08

    The air-surface exchange of particles can have a strong role in determining the amount, size, and chemical composition of particles in the troposphere. Here the authors consider only dry processes (deposition processes not directly aided by precipitation) and mostly address particles less than about 2 {micro}m in diameter (often referred to as submicron particles because most of such particles are less than 1 {micro}m in diameter). The processes that control the dry exchange of particulate material between the atmosphere and the surface of the Earth are numerous, highly varied, and sometimes poorly understood. As a result, determining which of the surface processes to parameterize or simulate in modeling the tropospheric mass budget of a particulate substance can be a significant challenge. Dry deposition, for example, can be controlled by a combination of Brownian diffusion, impaction, interception, and gravitational settling, depending on the size of the particles, the roughness of the surface on both micrometeorological and microscopic scales, the geometrical structure of vegetative canopies, and other surface characteristics such as wetness. Particles can be added to the lower atmosphere by resuspension from land surfaces and sea spray. The roles of rapid gas-to-particle conversion and growth or shrinkage of particles as a result of water condensation or evaporation in the lower few meters of the atmosphere can also have a significant impact on particle concentrations in the lower atmosphere. Here, a few micrometeorological observations and inferences on particle air-surface exchange are briefly addressed.

  6. Effect of particle size on fracture toughness of SiC/Al composite material

    NASA Technical Reports Server (NTRS)

    Flom, Y.; Arsenault, R. J.

    1989-01-01

    Discontinuous SiC/Al composites with SiC particles of different sizes were fabricated in order to study the role of particle size on the fracture process. The fracture process is confined to a very narrow band and takes place within the matrix in composites containing small SiC particle sizes. In the composite reinforced with SiC particles of 20 microns and above fracture of SiC begins to dominate. The matrix is influenced by the high density of dislocations generated at SiC/Al interfaces due to the difference in coefficient of thermal expansion between SiC and the Al matrix. Crack initiation fracture toughness does not depend on SiC particle size. Crack growth fracture toughness increases as the size of the SiC particle increase.

  7. Rai, A.C., Guo, B., Lin, C.-H., Zhang, J., Pei, J., and Chen, Q. 2013. "Ozone reaction with clothing and its initiated particle1 generation in an environmental chamber," Atmospheric Environment, 77, 885-892.2

    E-print Network

    Chen, Qingyan "Yan"

    with clothing and its initiated particle1 generation in an environmental chamber," Atmospheric Environment, 77, 885-892.2 3 Ozone reaction with clothing and its initiated particle generation in an environmental4 through14 ozone reactions with human skin and clothing. This investigation conducted chamber experiments

  8. Hazardous components and health effects of atmospheric aerosol particles: reactive oxygen species, soot, polycyclic aromatic compounds and allergenic proteins.

    PubMed

    Shiraiwa, Manabu; Selzle, Kathrin; Pöschl, Ulrich

    2012-08-01

    This review outlines recent advances in the investigation of the chemical properties, molecular interactions and health effects of hazardous compounds in atmospheric aerosols, in particular reactive oxygen species (ROS), soot, polycyclic aromatic compounds (PACs) and allergenic proteins. Epidemiological studies show correlations between air particulate matter and adverse health effects of air pollution including allergy, asthma, cardiovascular and respiratory diseases, but the causative relations and mechanisms of interaction on the molecular level are still unclear. ROS generated by photochemical and heterogeneous reactions in the atmosphere seem to play a key role in aerosol health effects and provide a direct link between atmospheric and physiological multiphase processes. Soot and PACs can trigger formation of ROS in vivo, leading to inflammation and cellular damage. PACs as well as allergenic proteins are efficiently oxygenated and nitrated upon exposure to ozone and nitrogen dioxide, which leads to an enhancement of their toxicity and allergenicity. PMID:22300277

  9. Complex experiment on the study of microphysical, chemical, and optical properties of aerosol particles and estimation of atmospheric aerosol contribution in the Earth radiation budget

    NASA Astrophysics Data System (ADS)

    Matvienko, G. G.; Belan, B. D.; Panchenko, M. V.; Romanovskii, O. A.; Sakerin, S. M.; Kabanov, D. M.; Turchinovich, S. A.; Turchinovich, Yu. S.; Eremina, T. A.; Kozlov, V. S.; Terpugova, S. A.; Pol'kin, V. V.; Yausheva, E. P.; Chernov, D. G.; Zuravleva, T. B.; Bedareva, T. V.; Odintsov, S. L.; Burlakov, V. D.; Arshinov, M. Yu.; Ivlev, G. A.; Savkin, D. E.; Fofonov, A. V.; Gladkikh, V. A.; Kamardin, A. P.; Belan, D. B.; Grishaev, M. V.; Belov, V. V.; Afonin, S. V.; Balin, Yu. S.; Kokhanenko, G. P.; Penner, I. E.; Samoilova, S. V.; Antokhin, P. N.; Arshinova, V. G.; Davydov, D. K.; Kozlov, A. V.; Pestunov, D. A.; Rasskazchikova, T. M.; Simonenkov, D. V.; Sklyadneva, T. K.; Tolmachev, G. N.; Belan, S. B.; Shmargunov, V. P.; Rostov, A. P.; Tikhomirova, O. V.; Shefer, N. A.; Safatov, A. S.; Kozlov, A. S.; Malyshkin, S. B.; Maksimova, T. A.

    2014-11-01

    The main aim of the work was complex experimental measurements of microphysical, chemical, and optical parameters of aerosol particles in the surface air layer and free atmosphere. From the measurement data, the entire set of aerosol optical parameters was retrieved, required for radiation calculations. Three measurement runs were carried out in 2013 within the experiment: in spring, when the aerosol generation maximum is observed, in summer (July), when the altitude of the atmospheric boundary layer is the highest, and in the late summer - early autumn, when the second nucleation period is recorded. The following instruments were used in the experiment: diffusion aerosol spectrometers (DAS), GRIMM photoelectric counters, angle-scattering nephelometers, aethalometer, SP-9/6 sun photometer, RE 318 Sun-Sky radiometer (AERONET), MS-53 pyrheliometer, MS-802 pyranometer, ASP aureole photometer, SSP scanning photometer, TU-134 Optik flying laboratory, Siberian lidar station, stationary multiwave lidar complex LOZA-M, spectrophotometric complex for measuring total ozone and NO2, multivariable instrument for measuring atmospheric parameters, METEO-2 USM, 2.4 AEHP-2.4m station for satellite data receive. Results of numerical calculations of solar down-fluxes on the Earth's surface were compared with the values measured in clear air in the summer periods in 2010—2012 in a background region of Siberian boreal zone. It was shown that the relative differences between model and experimental values of direct and total radiation do not exceed 1% and 3%, respectively, with accounting for instrumental errors and measurement error of atmospheric parameters. Thus, independent data on optical, meteorological, and microphysical atmospheric parameters allow mutual intercalibration and supplement and, hence, provide for qualitatively new data, which can explain physical nature of processes that form the vertical structure of the aerosol filed.

  10. A recirculation aerosol wind tunnel for evaluating aerosol samplers and measuring particle penetration through protective clothing materials.

    PubMed

    Jaques, Peter A; Hsiao, Ta-Chih; Gao, Pengfei

    2011-08-01

    A recirculation aerosol wind tunnel was designed to maintain a uniform airflow and stable aerosol size distribution for evaluating aerosol sampler performance and determining particle penetration through protective clothing materials. The oval-shaped wind tunnel was designed to be small enough to fit onto a lab bench, have optimized dimensions for uniformity in wind speed and particle size distributions, sufficient mixing for even distribution of particles, and minimum particle losses. Performance evaluation demonstrates a relatively high level of spatial uniformity, with a coefficient of variation of 1.5-6.2% for wind velocities between 0.4 and 2.8 m s(-1) and, in this range, 0.8-8.5% for particles between 50 and 450 nm. Aerosol concentration stabilized within the first 5-20 min with, approximately, a count median diameter of 135 nm and geometric standard deviation of 2.20. Negligible agglomerate growth and particle loss are suggested. The recirculation design appears to result in unique features as needed for our research. PMID:21831849

  11. The Effect of Organic Material on Heterogeneous Ice Nucleation - Insights from Microscopic Analysis of Field-Collected, Laboratory Generated, and Marine Biogenic Particles (Invited)

    NASA Astrophysics Data System (ADS)

    Knopf, D. A.

    2010-12-01

    Heterogeneous ice nucleation has been shown to play an important role in the formation of cirrus and mixed-phase clouds. Although their importance is widely acknowledged, the actual effects of aerosol particles on heterogeneous ice formation are insufficiently understood. Here, we present laboratory studies investigating the ice nucleation efficiency of organic