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Sample records for aerosol dispersion performance

  1. Physicochemical characterization and aerosol dispersion performance of organic solution advanced spray-dried cyclosporine A multifunctional particles for dry powder inhalation aerosol delivery

    PubMed Central

    Wu, Xiao; Zhang, Weifen; Hayes, Don; Mansour, Heidi M

    2013-01-01

    In this systematic and comprehensive study, inhalation powders of the polypeptide immunosuppressant drug – cyclosporine A – for lung delivery as dry powder inhalers (DPIs) were successfully designed, developed, and optimized. Several spray drying pump rates were rationally chosen. Comprehensive physicochemical characterization and imaging was carried out using scanning electron microscopy, hot-stage microscopy, differential scanning calorimetry, powder X-ray diffraction, Karl Fischer titration, laser size diffraction, and gravimetric vapor sorption. Aerosol dispersion performance was conducted using a next generation impactor with a Food and Drug Administration-approved DPI device. These DPIs displayed excellent aerosol dispersion performance with high values in emitted dose, respirable fraction, and fine particle fraction. In addition, novel multifunctional inhalation aerosol powder formulations of cyclosporine A with lung surfactant-mimic phospholipids were also successfully designed and developed by advanced organic solution cospray drying in closed mode. The lung surfactantmimic phospholipids were 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dipalmitoyl-snglycero- 3-(phosphor-rac-1-glycerol). These cyclosporine A lung surfactant-mimic aerosol powder formulations were comprehensively characterized. Powder X-ray diffraction and differential scanning calorimetry confirmed that the phospholipid bilayer structure in the solid state was preserved following advanced organic solution spray drying in closed mode. These novel multifunctional inhalation powders were optimized for DPI delivery with excellent aerosol dispersion performance and high aerosol performance parameters. PMID:23569375

  2. Development of dry powder inhaler formulation loaded with alendronate solid lipid nanoparticles: solid-state characterization and aerosol dispersion performance.

    PubMed

    Ezzati Nazhad Dolatabadi, Jafar; Hamishehkar, Hamed; Valizadeh, Hadi

    2015-01-01

    Alendronate sodium is a bisphosphonate drug used for the treatment of osteoporosis and acts as a specific inhibitor of osteoclast-mediated bone resorption. Inhalable solid lipid nanoparticles (SLNs) of the alendronate were successfully designed and developed by spray-dried and co-spray dried inhalable mannitol from aqueous solution. Emulsification technique using a simple homogenization method was used for preparation of SLNs. In vitro deposition of the aerosolized drug was studied using a Next Generation Impactor at 60 L/min following the methodology described in the European and United States Pharmacopeias. The Carr's Index, Hausner ratio and angle of repose were calculated as suitable criteria for estimation of the flow behavior of solids. Scanning electron microscopy showed spherical particle morphology of the respirable particles. The proposed spray-dried nanoparticulate-on-microparticles dry powders displayed good aerosol dispersion performance as dry powder inhalers with high values in emitted dose, fine particle fraction and mass median aerodynamic diameter. These results indicate that this novel inhalable spray-dried nanoparticulate-on-microparticles aerosol platform has great potential in systemic delivery of the drug. PMID:25220930

  3. Design, Characterization, and Aerosol Dispersion Performance Modeling of Advanced Spray-Dried Microparticulate/Nanoparticulate Mannitol Powders for Targeted Pulmonary Delivery as Dry Powder Inhalers

    PubMed Central

    Li, Xiaojian; Vogt, Frederick G.; Hayes, Don

    2014-01-01

    Abstract Background: The purpose was to design and characterize inhalable microparticulate/nanoparticulate dry powders of mannitol with essential particle properties for targeted dry powder delivery for cystic fibrosis mucolytic treatment by dilute organic solution spray drying, and, in addition, to tailor and correlate aerosol dispersion performance delivered as dry powder inhalers based on spray-drying conditions and solid-state physicochemical properties. Methods: Organic solution advanced spray drying from dilute solution followed by comprehensive solid-state physicochemical characterization and in vitro dry powder aerosolization were used. Results: The particle size distribution of the spray-dried (SD) powders was narrow, unimodal, and in the range of ∼500 nm to 2.0 μm. The particles possessed spherical particle morphology, relatively smooth surface morphology, low water content and vapor sorption (crystallization occurred at exposure above 65% relative humidity), and retention of crystallinity by polymorphic interconversion. The emitted dose, fine particle fraction (FPF), and respirable fraction (RF) were all relatively high. The mass median aerodynamic diameters were below 4 μm for all SD mannitol aerosols. Conclusion: The in vitro aerosol deposition stage patterns could be tailored based on spray-drying pump rate. Positive linear correlation was observed between both FPF and RF values with spray-drying pump rates. The interplay between various spray-drying conditions, particle physicochemical properties, and aerosol dispersion performance was observed and examined, which enabled tailoring and modeling of high aerosol deposition patterns. PMID:24502451

  4. Modelling Aerosol Dispersion in Urban Street Canyons

    NASA Astrophysics Data System (ADS)

    Tay, B. K.; Jones, D. P.; Gallagher, M. W.; McFiggans, G. B.; Watkins, A. P.

    2009-04-01

    Flow patterns within an urban street canyon are influenced by various micrometeorological factors. It also represents an environment where pollutants such as aerosols accumulate to high levels due to high volumes of traffic. As adverse health effects are being attributed to exposure to aerosols, an investigation of the dispersion of aerosols within such environments is of growing importance. In particular, one is concerned with the vertical structure of the aerosol concentration, the ventilation characteristics of the street canyon and the influence of aerosol microphysical processes. Due to the inherent heterogeneity of the aerosol concentrations within the street canyon and the lack of spatial resolution of measurement campaigns, these issues are an on-going debate. Therefore, a modelling tool is required to represent aerosol dispersion patterns to provide insights to results of past measurement campaigns. Computational Fluid Dynamics (CFD) models are able to predict detailed airflow patterns within urban geometries. This capability may be further extended to include aerosol dispersion, by an Euler-Euler multiphase approach. To facilitate the investigation, a two-dimensional, multiphase CFD tool coupled with the k-epsilon turbulence model and with the capability of modelling mixed convection flow regimes arising from both wind driven flows and buoyancy effects from heated walls was developed. Assuming wind blowing perpendicularly to the canyon axis and treating aerosols as a passive scalar, an attempt will be made to assess the sensitivities of aerosol vertical structure and ventilation characteristics to the various flow conditions. Numerical studies were performed using an idealized 10m by 10m canyon to represent a regular canyon and 10m by 5m to represent a deep one. An aerosol emission source was assigned on the centerline of the canyon to represent exhaust emissions. The vertical structure of the aerosols would inform future directives regarding the

  5. Method of dispersing particulate aerosol tracer

    DOEpatents

    O'Holleran, Thomas P.

    1988-01-01

    A particulate aerosol tracer which comprises a particulate carrier of sheet silicate composition having a particle size up to one micron, and a cationic dopant chemically absorbed in solid solution in the carrier. The carrier is preferably selected from the group consisting of natural mineral clays such as bentonite, and the dopant is selected from the group consisting of rare earth elements and transition elements. The tracers are dispersed by forming an aqueous salt solution with the dopant present as cations, dispersing the carriers in the solution, and then atomizing the solution under heat sufficient to superheat the solution droplets at a level sufficient to prevent reagglomeration of the carrier particles.

  6. Modeling of the dispersion of depleted uranium aerosol.

    PubMed

    Mitsakou, C; Eleftheriadis, K; Housiadas, C; Lazaridis, M

    2003-04-01

    Depleted uranium is a low-cost radioactive material that, in addition to other applications, is used by the military in kinetic energy weapons against armored vehicles. During the Gulf and Balkan conflicts concern has been raised about the potential health hazards arising from the toxic and radioactive material released. The aerosol produced during impact and combustion of depleted uranium munitions can potentially contaminate wide areas around the impact sites or can be inhaled by civilians and military personnel. Attempts to estimate the extent and magnitude of the dispersion were until now performed by complex modeling tools employing unclear assumptions and input parameters of high uncertainty. An analytical puff model accommodating diffusion with simultaneous deposition is developed, which can provide a reasonable estimation of the dispersion of the released depleted uranium aerosol. Furthermore, the period of the exposure for a given point downwind from the release can be estimated (as opposed to when using a plume model). The main result is that the depleted uranium mass is deposited very close to the release point. The deposition flux at a couple of kilometers from the release point is more than one order of magnitude lower than the one a few meters near the release point. The effects due to uncertainties in the key input variables are addressed. The most influential parameters are found to be atmospheric stability, height of release, and wind speed, whereas aerosol size distribution is less significant. The output from the analytical model developed was tested against the numerical model RPM-AERO. Results display satisfactory agreement between the two models. PMID:12705453

  7. A sensitivity analysis of volcanic aerosol dispersion in the stratosphere. [Mt. Fuego, Guatemala eruptions

    NASA Technical Reports Server (NTRS)

    Butler, C. F.

    1979-01-01

    A computer sensitivity analysis was performed to determine the uncertainties involved in the calculation of volcanic aerosol dispersion in the stratosphere using a 2 dimensional model. The Fuego volcanic event of 1974 was used. Aerosol dispersion processes that were included are: transport, sedimentation, gas phase sulfur chemistry, and aerosol growth. Calculated uncertainties are established from variations in the stratospheric aerosol layer decay times at 37 latitude for each dispersion process. Model profiles are also compared with lidar measurements. Results of the computer study are quite sensitive (factor of 2) to the assumed volcanic aerosol source function and the large variations in the parameterized transport between 15 and 20 km at subtropical latitudes. Sedimentation effects are uncertain by up to a factor of 1.5 because of the lack of aerosol size distribution data. The aerosol chemistry and growth, assuming that the stated mechanisms are correct, are essentially complete in several months after the eruption and cannot explain the differences between measured and modeled results.

  8. Note: Design and development of wireless controlled aerosol sampling network for large scale aerosol dispersion experiments

    SciTech Connect

    Gopalakrishnan, V.; Subramanian, V.; Baskaran, R.; Venkatraman, B.

    2015-07-15

    Wireless based custom built aerosol sampling network is designed, developed, and implemented for environmental aerosol sampling. These aerosol sampling systems are used in field measurement campaign, in which sodium aerosol dispersion experiments have been conducted as a part of environmental impact studies related to sodium cooled fast reactor. The sampling network contains 40 aerosol sampling units and each contains custom built sampling head and the wireless control networking designed with Programmable System on Chip (PSoC™) and Xbee Pro RF modules. The base station control is designed using graphical programming language LabView. The sampling network is programmed to operate in a preset time and the running status of the samplers in the network is visualized from the base station. The system is developed in such a way that it can be used for any other environment sampling system deployed in wide area and uneven terrain where manual operation is difficult due to the requirement of simultaneous operation and status logging.

  9. Note: Design and development of wireless controlled aerosol sampling network for large scale aerosol dispersion experiments

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, V.; Subramanian, V.; Baskaran, R.; Venkatraman, B.

    2015-07-01

    Wireless based custom built aerosol sampling network is designed, developed, and implemented for environmental aerosol sampling. These aerosol sampling systems are used in field measurement campaign, in which sodium aerosol dispersion experiments have been conducted as a part of environmental impact studies related to sodium cooled fast reactor. The sampling network contains 40 aerosol sampling units and each contains custom built sampling head and the wireless control networking designed with Programmable System on Chip (PSoC™) and Xbee Pro RF modules. The base station control is designed using graphical programming language LabView. The sampling network is programmed to operate in a preset time and the running status of the samplers in the network is visualized from the base station. The system is developed in such a way that it can be used for any other environment sampling system deployed in wide area and uneven terrain where manual operation is difficult due to the requirement of simultaneous operation and status logging.

  10. Development of an aerosol dispersion test to detect early changes in lung function

    SciTech Connect

    McCawley, M.; Lippmann, M.

    1988-07-01

    The dispersion of a 0.5 micron aerosol bolus during tidal breathing differs significantly (p less than 0.0001) between a group of smokers (with approximately 20 pack-years average exposure) and a comparable group of nonsmokers. Their mean differences in standard respiratory function indexes from spirometry (forced vital capacity (FVC), forced expiratory volume in one second (FEV1), mean forced expiratory flow during the middle half of the FVC (FEF25-75)) were smaller and not statistically significant. The test is simple to perform and may be done as quickly as spirometry but without using a forced exhalation. Comparison of the coefficients of variation for the dispersion test and FEV1 indicate that the aerosol dispersion test may be useful in epidemiologic investigations either by reducing the required population size or increasing the level of confidence.

  11. 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.

  12. Note: Design and development of wireless controlled aerosol sampling network for large scale aerosol dispersion experiments.

    PubMed

    Gopalakrishnan, V; Subramanian, V; Baskaran, R; Venkatraman, B

    2015-07-01

    Wireless based custom built aerosol sampling network is designed, developed, and implemented for environmental aerosol sampling. These aerosol sampling systems are used in field measurement campaign, in which sodium aerosol dispersion experiments have been conducted as a part of environmental impact studies related to sodium cooled fast reactor. The sampling network contains 40 aerosol sampling units and each contains custom built sampling head and the wireless control networking designed with Programmable System on Chip (PSoC™) and Xbee Pro RF modules. The base station control is designed using graphical programming language LabView. The sampling network is programmed to operate in a preset time and the running status of the samplers in the network is visualized from the base station. The system is developed in such a way that it can be used for any other environment sampling system deployed in wide area and uneven terrain where manual operation is difficult due to the requirement of simultaneous operation and status logging. PMID:26233420

  13. The effect of ozone exposure on the dispersion of inhaled aerosol boluses in healthy human subjects

    SciTech Connect

    Keefe, M.J.; Bennett, W.D.; DeWitt, P.; Seal, E.; Strong, A.A.; Gerrity, T.R. )

    1991-07-01

    Acute exposure of humans to low levels of ozone are known to cause decreases in FVC and increases in SRaw. These alterations in lung function do not, however, elucidate the potential for acute small airway responses. In this study we employed a test of aerosol dispersion to examine the potential effects of ozone on small airways in humans. Twenty-two healthy nonsmoking male volunteers were exposed to 0.4 ppm ozone for 1 h while exercising at 20 L/min/m2 body surface area. Before and immediately after exposure, tests of spirometry (FVC, FEV1, and FEF25-75) and plethysmography (Raw and SRaw) were performed. Subjects also performed an aerosol dispersion test before and after exposure. Each test involved a subject inhaling five to seven breaths of a 300-ml bolus of a 0.5 micron triphenyl phosphate aerosol injected into a 2-L tidal volume. The bolus was injected into the tidal breath at three different depths: at Depth A the bolus was injected after 1.6 L of clean air were inhaled from FRC, at Depth B after 1.2 L, and at Depth C after 1.2 L but with inhalation beginning from RV. The primary measure of bolus dispersion was the expired half-width (HW). Secondary measures were the ratio (expressed as percent) of peak exhaled aerosol concentration to peak inhaled concentration (PR), shift in the median bolus volume between inspiration and expiration (VS), and percent of total aerosol recovered (RC). Changes in pulmonary function after ozone exposure were consistent with previous findings.

  14. Effect of ozone exposure on the dispersion of inhaled aerosol boluses in healthy human subjects

    SciTech Connect

    Keefe, M.J.; Bennett, W.D.; Dewitt, P.; Seal, E.; Strong, A.A.

    1990-12-06

    Acute exposure of humans to low levels of ozone are known to cause decreases FVC and increases sRaw. These alterations in lung function do not, however, elucidate the potential for acute small airways responses. In the study the authors employed a test of aerosol dispersion to examine the potential effects of ozone on small airways in humans. Twenty-two healthy non-smoking male volunteers were exposed to 0.4 ppm ozone for one hour while exercising at 20 l/min/m{sup 2} (BSA). Prior to and immediately following exposure, tests of spirometry (FVC, FEV1, and FEF25-75) and plethysmography (Raw and sRaw) were performed. Subjects also performed an aerosol dispersion test before and after exposure. Each test involved a subject inhaling five to seven breaths of a 300 ml bolus of a 0.5 micrometers triphenyl phosphate (TPP) aerosol injected into a 2 liters tidal volume. The bolus was injected into the tidal breath at three different depths: at depth A the bolus was injected after 1.6 liters of clean air was inhaled from FRC; at depth B after 1.2 liters; and at depth C after 1.2 liters but with inhalation beginning from RV. The primary measure of bolus dispersion was the expired half-width (HW).

  15. Influence of room geometry and ventilation rate on airflow and aerosol dispersion: implications for worker protection.

    PubMed

    Whicker, Jeffrey J; Wasiolek, Piotr T; Tavani, Rebecca A

    2002-01-01

    Knowledge of dispersion rates and patterns of radioactive aerosols and gases through workrooms is critical for understanding human exposure and for developing strategies for worker protection. The dispersion within rooms can be influenced by complex interactions between numerous variables, but especially ventilation design and room furnishings. For this study, dependence of airflow and aerosol dispersion on workroom geometry (furnishings) and ventilation rate were studied in an experimental room that was designed to approximate a plutonium laboratory. Three different configurations of simulated gloveboxes and two ventilation rates (approximately 6 and 12 air exchanges per hour) were studied. A sonic anemometer was used to measure airflow parameters including all three components of air velocity vectors and turbulence intensity distributions at multiple locations and heights. Aerosol dispersion rates and patterns were measured by releasing aerosols multiple times from six different locations. Aerosol particle concentrations resolved in time and space were measured using 16 multiplexed laser particle counters. Comparisons were made of air velocities, turbulence, and aerosol transport across different ventilation rates and room configurations. A strong influence of ventilation rate on aerosol dispersion rates and air velocity was found, and changes in room geometry had significant effects on aerosol dispersion rates and patterns. These results are important with regards to constant evaluation of placement of air sampling equipment, benchmarking numerical models of room airflow, and design of ventilation and room layouts with consideration of worker safety. PMID:11768799

  16. Aerosol Deposition and Solar Panel Performance

    NASA Astrophysics Data System (ADS)

    Arnott, W. P.; Rollings, A.; Taylor, S. J.; Parks, J.; Barnard, J.; Holmes, H.

    2015-12-01

    Passive and active solar collector farms are often located in relatively dry desert regions where cloudiness impacts are minimized. These farms may be susceptible to reduced performance due to routine or episodic aerosol deposition on collector surfaces. Intense episodes of wind blown dust deposition may negatively impact farm performance, and trigger need to clean collector surfaces. Aerosol deposition rate depends on size, morphology, and local meteorological conditions. We have developed a system for solar panel performance testing under real world conditions. Two identical 0.74 square meter solar panels are deployed, with one kept clean while the other receives various doses of aerosol deposition or other treatments. A variable load is used with automation to record solar panel maximum output power every 10 minutes. A collocated sonic anemometer measures wind at 10 Hz, allowing for both steady and turbulent characterization to establish a link between wind patterns and particle distribution on the cells. Multispectral photoacoustic instruments measure aerosol light scattering and absorption. An MFRSR quantifies incoming solar radiation. Solar panel albedo is measured along with the transmission spectra of particles collected on the panel surface. Key questions are: At what concentration does aerosol deposition become a problem for solar panel performance? What are the meteorological conditions that most strongly favor aerosol deposition, and are these predictable from current models? Is it feasible to use the outflow from an unmanned aerial vehicle hovering over solar panels to adequately clean their surface? Does aerosol deposition from episodes of nearby forest fires impact performance? The outlook of this research is to build a model that describes environmental effects on solar panel performance. Measurements from summer and fall 2015 will be presented along with insights gleaned from them.

  17. SAGE measurements of the stratospheric aerosol dispersion and loading from the Soufriere Volcano

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Kent, G. S.; Yue, G. K.; Cunnold, D. M.

    1981-01-01

    Explosions of the Soufriere volcano on the Caribbean Island of St. Vincent reduced two major stratospheric plumes which the stratospheric aerosol and gas experiment (SAGE) satellite tracked to West Africa and the North Atlantic Ocean. The total mass of the stratospheric ejecta measured is less than 0.5% of the global stratospheric aerosol burden. No significant temperature or climate perturbation is expected. It is found that the movement and dispersion of the plumes agree with those deduced from high altitude meteorological data and dispersion theory. The stratospheric aerosol dispersion and loading from the Soufrier volcano was measured.

  18. Near Real{time Data Assimilation for the HYSPLIT Aerosol Dispersion Model

    NASA Astrophysics Data System (ADS)

    Kalpakis, K.; Yang, S.; Yesha, Y.

    2010-12-01

    useful in improving HYSPLIT forecasts of smoke from wildfires. Currently, the Ikhana AMS fire missions team provides L1B data which are very useful in themselves, but no level 2 to the best of our knowledge. For our application, it would very useful to have an AOD data product for these datasets. A possible path for deriving AOD data the AMS sensor onboard UAVs would be to utilize the DRL code for deriving the MODIS AOD from MODIS L1B data, due to the sensor similarities. Developing such code would be very useful for wildfire smoke prediction applications. Our near real-time data assimilation system helps in bridging the gap between predictions and real-time observations, for more accurate and timely aerosol dispersion forecasts. Keywords: data assimilation, HYSPLIT, forecast model performance, real-time, ensemble Kalman filter, aerosol dispersion and concentration.

  19. Pay Dispersion and Performance in Teams

    PubMed Central

    Bucciol, Alessandro; Foss, Nicolai J.; Piovesan, Marco

    2014-01-01

    Extant research offers conflicting predictions about the effect of pay dispersion on team performance. We collected a unique dataset from the Italian soccer league to study the effect of intra-firm pay dispersion on team performance, under different definitions of what constitutes a “team”. This peculiarity of our dataset can explain the conflicting evidence. Indeed, we also find positive, null, and negative effects of pay dispersion on team performance, using the same data but different definitions of team. Our results show that when the team is considered to consist of only the members who directly contribute to the outcome, high pay dispersion has a detrimental impact on team performance. Enlarging the definition of the team causes this effect to disappear or even change direction. Finally, we find that the detrimental effect of pay dispersion is due to worse individual performance, rather than a reduction of team cooperation. PMID:25397615

  20. Pay dispersion and performance in teams.

    PubMed

    Bucciol, Alessandro; Foss, Nicolai J; Piovesan, Marco

    2014-01-01

    Extant research offers conflicting predictions about the effect of pay dispersion on team performance. We collected a unique dataset from the Italian soccer league to study the effect of intra-firm pay dispersion on team performance, under different definitions of what constitutes a "team". This peculiarity of our dataset can explain the conflicting evidence. Indeed, we also find positive, null, and negative effects of pay dispersion on team performance, using the same data but different definitions of team. Our results show that when the team is considered to consist of only the members who directly contribute to the outcome, high pay dispersion has a detrimental impact on team performance. Enlarging the definition of the team causes this effect to disappear or even change direction. Finally, we find that the detrimental effect of pay dispersion is due to worse individual performance, rather than a reduction of team cooperation. PMID:25397615

  1. Effects of Carbon Dioxide Aerosols on the Viability of Escherichia coli during Biofilm Dispersal

    PubMed Central

    Singh, Renu; Monnappa, Ajay K.; Hong, Seongkyeol; Mitchell, Robert J.; Jang, Jaesung

    2015-01-01

    A periodic jet of carbon dioxide (CO2) aerosols is a very quick and effective mechanical technique to remove biofilms from various substrate surfaces. However, the impact of the aerosols on the viability of bacteria during treatment has never been evaluated. In this study, the effects of high-speed CO2 aerosols, a mixture of solid and gaseous CO2, on bacteria viability was studied. It was found that when CO2 aerosols were used to disperse biofilms of Escherichia coli, they led to a significant loss of viability, with approximately 50% of the dispersed bacteria killed in the process. By comparison, 75.6% of the biofilm-associated bacteria were viable when gently dispersed using Proteinase K and DNase I. Indirect proof that the aerosols are damaging the bacteria was found using a recombinant E. coli expressing the cyan fluorescent protein, as nearly half of the fluorescence was found in the supernatant after CO2 aerosol treatment, while the rest was associated with the bacterial pellet. In comparison, the supernatant fluorescence was only 9% when the enzymes were used to disperse the biofilm. As such, these CO2 aerosols not only remove biofilm-associated bacteria effectively but also significantly impact their viability by disrupting membrane integrity. PMID:26345492

  2. Spent fuel sabotage test program, characterization of aerosol dispersal : interim final report.

    SciTech Connect

    Gregson, Michael Warren; Brockmann, John E.; Loiseau, Olivier; Klennert, Lindsay A.; Nolte, Oliver; Molecke, Martin Alan; Autrusson, Bruno A.; Koch, Wolfgang; Pretzsch, Gunter Guido; Brucher, Wenzel; Steyskal, Michele D.

    2008-03-01

    This multinational, multi-phase spent fuel sabotage test program is quantifying the aerosol particles produced when the products of a high energy density device (HEDD) interact with and explosively particulate test rodlets that contain pellets of either surrogate materials or actual spent fuel. This program provides source-term data that are relevant to plausible sabotage scenarios in relation to spent fuel transport and storage casks and associated risk assessments. We present details and significant results obtained from this program from 2001 through 2007. Measured aerosol results include: respirable fractions produced; amounts, nuclide content, and produced particle size distributions and morphology; measurements of volatile fission product species enhanced sorption--enrichment factors onto respirable particles; and, status on determination of the spent fuel ratio, SFR, needed for scaling studies. Emphasis is provided on recent Phase 3 tests using depleted uranium oxide pellets plus non-radioactive fission product dopants in surrogate spent fuel test rodlets, plus the latest surrogate cerium oxide results and aerosol laboratory supporting calibration work. The DUO{sub 2}, CeO{sub 2}, plus fission product dopant aerosol particle results are compared with available historical data. We also provide a status review on continuing preparations for the final Phase 4 in this program, tests using individual short rodlets containing actual spent fuel from U.S. PWR reactors, with both high- and lower-burnup fuel. The source-term data, aerosol results, and program design have been tailored to support and guide follow-on computer modeling of aerosol dispersal hazards and radiological consequence assessments. This spent fuel sabotage, aerosol test program was performed primarily at Sandia National Laboratories, with support provided by both the U.S. Department of Energy and the Nuclear Regulatory Commission. This program has significant input from, and is cooperatively

  3. DISPERSION OF AEROSOL BOLUSES IN THE HUMAN LUNG: DEPENDENCE ON LUNG VOLUME, BOLUS VOLUME, AND GENDER

    EPA Science Inventory

    The dispersion of aerosol boluses in the human lungs has been studied in health and disease by other investigators as a means of investigating convective mixing. owever, there are only limited data on the roles played in dispersion by critical factors such as the volume of inhale...

  4. NEXT Ion Thruster Performance Dispersion Analyses

    NASA Technical Reports Server (NTRS)

    Soulas, George C.; Patterson, Michael J.

    2008-01-01

    The NEXT ion thruster is a low specific mass, high performance thruster with a nominal throttling range of 0.5 to 7 kW. Numerous engineering model and one prototype model thrusters have been manufactured and tested. Of significant importance to propulsion system performance is thruster-to-thruster performance dispersions. This type of information can provide a bandwidth of expected performance variations both on a thruster and a component level. Knowledge of these dispersions can be used to more conservatively predict thruster service life capability and thruster performance for mission planning, facilitate future thruster performance comparisons, and verify power processor capabilities are compatible with the thruster design. This study compiles the test results of five engineering model thrusters and one flight-like thruster to determine unit-to-unit dispersions in thruster performance. Component level performance dispersion analyses will include discharge chamber voltages, currents, and losses; accelerator currents, electron backstreaming limits, and perveance limits; and neutralizer keeper and coupling voltages and the spot-to-plume mode transition flow rates. Thruster level performance dispersion analyses will include thrust efficiency.

  5. Aerosol bolus dispersion in acinar airways--influence of gravity and airway asymmetry.

    PubMed

    Ma, Baoshun; Darquenne, Chantal

    2012-08-01

    The aerosol bolus technique can be used to estimate the degree of convective mixing in the lung; however, contributions of different lung compartments to measured dispersion cannot be differentiated unambiguously. To estimate dispersion in the distal lung, we studied the effect of gravity and airway asymmetry on the dispersion of 1 μm-diameter particle boluses in three-dimensional computational models of the lung periphery, ranging from a single alveolar sac to four-generation (g4) structures of bifurcating airways that deformed homogeneously during breathing. Boluses were introduced at the beginning of a 2-s inhalation, immediately followed by a 3-s exhalation. Dispersion was estimated by the half-width of the exhaled bolus. Dispersion was significantly affected by the spatial orientation of the models in normal gravity and was less in zero gravity than in normal gravity. Dispersion was strongly correlated with model volume in both normal and zero gravity. Predicted pulmonary dispersion based on a symmetric g4 acinar model was 391 ml and 238 ml under normal and zero gravity, respectively. These results accounted for a significant amount of dispersion measured experimentally. In zero gravity, predicted dispersion in a highly asymmetric model accounted for ∼20% of that obtained in a symmetric model with comparable volume and number of alveolated branches, whereas normal gravity dispersions were comparable in both models. These results suggest that gravitational sedimentation and not geometrical asymmetry is the dominant factor in aerosol dispersion in the lung periphery. PMID:22678957

  6. Aerosol bolus dispersion in acinar airways—influence of gravity and airway asymmetry

    PubMed Central

    Ma, Baoshun

    2012-01-01

    The aerosol bolus technique can be used to estimate the degree of convective mixing in the lung; however, contributions of different lung compartments to measured dispersion cannot be differentiated unambiguously. To estimate dispersion in the distal lung, we studied the effect of gravity and airway asymmetry on the dispersion of 1 μm-diameter particle boluses in three-dimensional computational models of the lung periphery, ranging from a single alveolar sac to four-generation (g4) structures of bifurcating airways that deformed homogeneously during breathing. Boluses were introduced at the beginning of a 2-s inhalation, immediately followed by a 3-s exhalation. Dispersion was estimated by the half-width of the exhaled bolus. Dispersion was significantly affected by the spatial orientation of the models in normal gravity and was less in zero gravity than in normal gravity. Dispersion was strongly correlated with model volume in both normal and zero gravity. Predicted pulmonary dispersion based on a symmetric g4 acinar model was 391 ml and 238 ml under normal and zero gravity, respectively. These results accounted for a significant amount of dispersion measured experimentally. In zero gravity, predicted dispersion in a highly asymmetric model accounted for ∼20% of that obtained in a symmetric model with comparable volume and number of alveolated branches, whereas normal gravity dispersions were comparable in both models. These results suggest that gravitational sedimentation and not geometrical asymmetry is the dominant factor in aerosol dispersion in the lung periphery. PMID:22678957

  7. Atmospheric Dispersion of Sodium Aerosol due to a Sodium Leak in a Fast Breeder Reactor Complex

    NASA Astrophysics Data System (ADS)

    Punitha, G.; Sudha, A. Jasmin; Kasinathan, N.; Rajan, M.

    Liquid sodium at high temperatures (470 K to 825 K) is used as the primary and secondary coolant in Liquid Metal cooled Fast Breeder Reactors (LMFBR). In the event of a postulated sodium leak in the Steam Generator Building (SGB) of a LMFBR, sodium readily combusts in the ambient air, especially at temperatures above 523 K. Intense sodium fire results and sodium oxide fumes are released as sodium aerosols. Sodium oxides are readily converted to sodium hydroxide in air due to the presence of moisture in it. Hence, sodium aerosols are invariably in the form of particulate sodium hydroxide. These aerosols damage not only the equipment and instruments due to their corrosive nature but also pose health hazard to humans. Hence, it is essential to estimate the concentration of sodium aerosols within the plant boundary for a sodium leak event. The Gaussian Plume Dispersion Model can obtain the atmospheric dispersion of sodium aerosols in an open terrain. However, this model does not give accurate results for dispersion in spaces close to the point of release and with buildings in between. The velocity field due to the wind is altered to a large extent by the intervening buildings and structures. Therefore, a detailed 3-D estimation of the velocity field and concentration has to be obtained through rigorous computational fluid dynamics (CFD) approach. PHOENICS code has been employed to determine concentration of sodium aerosols at various distances from the point of release. The dispersion studies have been carried out for the release of sodium aerosols at different elevations from the ground and for different wind directions.

  8. Performance of personal inhalable aerosol samplers in very slowly moving air when facing the aerosol source.

    PubMed

    Witschger, O; Grinshpun, S A; Fauvel, S; Basso, G

    2004-06-01

    While personal aerosol samplers have been characterized primarily based on wind tunnel tests conducted at relatively high wind speeds, modern indoor occupational environments are usually represented by very slow moving air. Recent surveys suggest that elevated levels of occupational exposure to inhalable airborne particles are typically observed when the worker, operating in the vicinity of the dust source, faces the source. Thus, the first objective of this study was to design and test a new, low cost experimental protocol for measuring the sampling efficiency of personal inhalable aerosol samplers in the vicinity of the aerosol source when the samplers operate in very slowly moving air. In this system, an aerosol generator, which is located in the centre of a room-sized non-ventilated chamber, continuously rotates and omnidirectionally disperses test particles of a specific size. The test and reference samplers are equally distributed around the source at the same distance from the centre and operate in parallel (in most of our experiments, the total number of simultaneously operating samplers was 15). Radial aerosol transport is driven by turbulent diffusion and some natural convection. For each specific particle size and the sampler, the aerosol mass concentration is measured by weighing the collection filter. The second objective was to utilize the new protocol to evaluate three widely used aerosol samplers: the IOM Personal Inhalable Sampler, the Button Personal Inhalable Aerosol Sampler and the 25 mm Millipore filter holder (closed-face C25 cassette). The sampling efficiencies of each instrument were measured with six particle fractions, ranging from 6.9 to 76.9 micro m in their mass median aerodynamic diameter. The Button Sampler efficiency data demonstrated a good agreement with the standard inhalable convention and especially with the low air movement inhalabilty curve. The 25 mm filter holder was found to considerably under-sample the particles larger

  9. Sensitivity of volcanic aerosol dispersion to meteorological conditions: A Pinatubo case study

    NASA Astrophysics Data System (ADS)

    Jones, Anthony C.; Haywood, James M.; Jones, Andy; Aquila, Valentina

    2016-06-01

    Using a global climate model (Hadley Centre Global Environment Model version 2-Carbon Cycle Stratosphere ) with a well-resolved stratosphere, we test the sensitivity of volcanic aerosol plume dispersion to meteorological conditions by simulating 1 day Mount Pinatubo-like eruptions on 10 consecutive days. The dispersion of the volcanic aerosol is found to be highly sensitive to the ambient meteorology for low-altitude eruptions (16-18 km), with this variability related to anomalous anticyclonic activity along the subtropical jet, which affects the permeability of the tropical pipe and controls the amount of aerosol that is retained by the tropical reservoir. Conversely, a high-altitude eruption scenario (19-29 km) exhibits low meteorological variability. Overcoming day-to-day meteorological variability by spreading the emission over 10 days is shown to produce insufficient radiative heating to loft the aerosol into the stratospheric tropical aerosol reservoir for the low eruption scenario. This results in limited penetration of aerosol into the southern hemisphere (SH) in contrast to the SH transport observed after the Pinatubo eruption. Our results have direct implications for the accurate simulation of past/future volcanic eruptions and volcanically forced climate changes, such as Intertropical Convergence Zone displacement.

  10. EFFECT OF OZONE EXPOSURE ON THE DISPERSION OF INHALED AEROSOL BOLUSES IN HEALTHY HUMAN SUBJECTS

    EPA Science Inventory

    Acute exposure of humans to low levels of ozone are known to cause decreases FVC and increases sRaw. hese alterations in lung function do not, however, elucidate the potential for acute small airways responses. n this study we employed a test of aerosol dispersion to examine the ...

  11. Performance evaluation of newly developed portable aerosol sizers used for nanomaterial aerosol measurements.

    PubMed

    Yamada, Maromu; Takaya, Mitsutoshi; Ogura, Isamu

    2015-01-01

    Nanomaterial particles exhibit a wide range of sizes through the formation of agglomerates/aggregates. To assess nanomaterial exposure in the workplace, accurate measurements of particle concentration and size distribution are needed. In this study, we evaluated the performance of two recently commercialized instruments: a portable scanning mobility particle sizer (SMPS) (NanoScan, TSI Inc.), which measures particle size distribution between 10 and 420 nm and an optical particle sizer (OPS, TSI Inc.), which measures particle size distribution between 300 and 10,000 nm. We compared the data measured by these instruments to conventional instruments (i.e., a widely used laboratory SMPS and an optical particle counter (OPC)) using nano-TiO(2) powder as test aerosol particles. The results showed obvious differences in the size distributions between the new and old SMPSs. A possible reason for the differences is that the cyclone inlet of the new SMPS (NanoScan) acted as a disperser of the weakly agglomerated particles and consequently the concentration increased through the breakup of the agglomerates. On the other hand, the particle concentration and size distributions measured by the OPS were similar to the OPC. When indoor aerosol particles were measured, the size distribution measured by the NanoScan was similar to the laboratory SMPS. PMID:26320727

  12. Performance evaluation of newly developed portable aerosol sizers used for nanomaterial aerosol measurements

    PubMed Central

    YAMADA, Maromu; TAKAYA, Mitsutoshi; OGURA, Isamu

    2015-01-01

    Nanomaterial particles exhibit a wide range of sizes through the formation of agglomerates/aggregates. To assess nanomaterial exposure in the workplace, accurate measurements of particle concentration and size distribution are needed. In this study, we evaluated the performance of two recently commercialized instruments: a portable scanning mobility particle sizer (SMPS) (NanoScan, TSI Inc.), which measures particle size distribution between 10 and 420 nm and an optical particle sizer (OPS, TSI Inc.), which measures particle size distribution between 300 and 10,000 nm. We compared the data measured by these instruments to conventional instruments (i.e., a widely used laboratory SMPS and an optical particle counter (OPC)) using nano-TiO2 powder as test aerosol particles. The results showed obvious differences in the size distributions between the new and old SMPSs. A possible reason for the differences is that the cyclone inlet of the new SMPS (NanoScan) acted as a disperser of the weakly agglomerated particles and consequently the concentration increased through the breakup of the agglomerates. On the other hand, the particle concentration and size distributions measured by the OPS were similar to the OPC. When indoor aerosol particles were measured, the size distribution measured by the NanoScan was similar to the laboratory SMPS. PMID:26320727

  13. Aerosolization characteristics of dry powder inhaler formulations for the excipient enhanced growth (EEG) application: effect of spray drying process conditions on aerosol performance.

    PubMed

    Son, Yoen-Ju; Worth Longest, P; Hindle, Michael

    2013-02-25

    The aim of this study was to develop a spray dried submicrometer powder formulation suitable for the excipient enhanced growth (EEG) application. Combination particles were prepared using the Buchi Nano spray dryer B-90. A number of spray drying and formulation variables were investigated with the aims of producing dry powder formulations that were readily dispersed upon aerosolization and maximizing the fraction of submicrometer particles. Albuterol sulfate, mannitol, L-leucine, and poloxamer 188 were selected as a model drug, hygroscopic excipient, dispersibility enhancer and surfactant, respectively. Formulations were assessed by scanning electron microscopy and aerosol performance following aerosolization using an Aerolizer dry powder inhaler (DPI). In vitro drug deposition was studied using a realistic mouth-throat (MT) model. Based on the in vitro aerosolization results, the best performing submicrometer powder formulation consisted of albuterol sulfate, mannitol, L-leucine and poloxamer 188 in a ratio of 30:48:20:2, containing 0.5% solids in a water:ethanol (80:20%, v/v) solution which was spray dried at 70 °C. The submicrometer particle fraction (FPF(1 μm/ED)) of this final formulation was 28.3% with more than 80% of the capsule contents being emitted during aerosolization. This formulation also showed 4.1% MT deposition. The developed combination formulation delivered a powder aerosol developed for the EEG application with high dispersion efficiency and low MT deposition from a convenient DPI device platform. PMID:23313343

  14. Aerosolization Characteristics of Dry Powder Inhaler Formulations for the Excipient Enhanced Growth (EEG) Application: Effect of Spray Drying Process Conditions on Aerosol Performance

    PubMed Central

    Son, Yoen-Ju; Longest, P. Worth; Hindle, Michael

    2013-01-01

    The aim of this study was to develop a spray dried submicrometer powder formulation suitable for the excipient enhanced growth (EEG) application. Combination particles were prepared using the Buchi Nano spray dryer B-90. A number of spray drying and formulation variables were investigated with the aims of producing dry powder formulations that were readily dispersed upon aerosolization and maximizing the fraction of submicrometer particles. Albuterol sulfate, mannitol, L-leucine, and poloxamer 188 were selected as a model drug, hygroscopic excipient, dispersibility enhancer and surfactant, respectively. Formulations were assessed by scanning electron microscopy and aerosol performance following aerosolization using an Aerolizer® dry powder inhaler (DPI). In vitro drug deposition was studied using a realistic mouth-throat (MT) model. Based on the in vitro aerosolization results, the best performing submicrometer powder formulation consisted of albuterol sulfate, mannitol, L-leucine and poloxamer 188 in a ratio of 30:48:20:2, containing 0.5% solids in a water:ethanol (80:20% v/v) solution which was spray dried at 70 °C. The submicrometer particle fraction (FPF1μm/ED) of this final formulation was 28.3% with more than 80% of the capsule contents being emitted during aerosolization. This formulation also showed 4.1% MT deposition. The developed combination formulation delivered a powder aerosol developed for the EEG application with high dispersion efficiency and low MT deposition from a convenient DPI device platform. PMID:23313343

  15. Performance Evaluation of Dense Gas Dispersion Models.

    NASA Astrophysics Data System (ADS)

    Touma, Jawad S.; Cox, William M.; Thistle, Harold; Zapert, James G.

    1995-03-01

    This paper summarizes the results of a study to evaluate the performance of seven dense gas dispersion models using data from three field experiments. Two models (DEGADIS and SLAB) are in the public domain and the other five (AIRTOX, CHARM, FOCUS, SAFEMODE, and TRACE) are proprietary. The field data used are the Desert Tortoise pressurized ammonia releases, Burro liquefied natural gas spill tests, and the Goldfish anhydrous hydrofluoric acid spill experiments. Desert Tortoise and Goldfish releases were simulated as horizontal jet releases, and Burro as a liquid pool. Performance statistics were used to compare maximum observed concentrations and plume half-width to those predicted by each model. Model performance varied and no model exhibited consistently good performance across all three databases. However, when combined across the three databases, all models performed within a factor of 2. Problems encountered are discussed in order to help future investigators.

  16. Deposition and dispersion of 1-micrometer aerosol boluses in the human lung: effect of micro- and hypergravity.

    PubMed

    Darquenne, C; West, J B; Prisk, G K

    1998-10-01

    We performed bolus inhalations of 1-micrometer particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (microG) and in approximately 1.6 G. Boluses of approximately 70 ml were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 200 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The deposition, dispersion, and position of the bolus in the expired gas were calculated from these data. For Vp >/=400 ml, both deposition and dispersion increased with Vp and were strongly gravity dependent, with the greatest deposition and dispersion occurring for the largest G level. At Vp = 800 ml, deposition and dispersion increased from 33.9% and 319 ml in microG to 56.9% and 573 ml at approximately 1.6 G, respectively (P < 0.05). At each G level, the bolus was expired at a smaller volume than Vp, and this volume became smaller with increasing Vp. Although dispersion was lower in microG than in 1 G and approximately 1.6 G, it still increased steadily with increasing Vp, showing that nongravitational ventilatory inhomogeneity is partly responsible for dispersion in the human lung. PMID:9760313

  17. Deposition and dispersion of 1-micrometer aerosol boluses in the human lung: effect of micro- and hypergravity

    NASA Technical Reports Server (NTRS)

    Darquenne, C.; West, J. B.; Prisk, G. K.

    1998-01-01

    We performed bolus inhalations of 1-micrometer particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (microG) and in approximately 1.6 G. Boluses of approximately 70 ml were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 200 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The deposition, dispersion, and position of the bolus in the expired gas were calculated from these data. For Vp >/=400 ml, both deposition and dispersion increased with Vp and were strongly gravity dependent, with the greatest deposition and dispersion occurring for the largest G level. At Vp = 800 ml, deposition and dispersion increased from 33.9% and 319 ml in microG to 56.9% and 573 ml at approximately 1.6 G, respectively (P < 0.05). At each G level, the bolus was expired at a smaller volume than Vp, and this volume became smaller with increasing Vp. Although dispersion was lower in microG than in 1 G and approximately 1.6 G, it still increased steadily with increasing Vp, showing that nongravitational ventilatory inhomogeneity is partly responsible for dispersion in the human lung.

  18. Numerical simulation of advection fog formation on multi-disperse aerosols due to combustion-related pollutants

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Liaw, G. S.

    1980-01-01

    The effects of multi-disperse distribution of the aerosol population are presented. Single component and multi-component aerosol species on the condensation/nucleation processes which affect the reduction in visibility are described. The aerosol population with a high particle concentration provided more favorable conditions for the formation of a denser fog than the aerosol population with a greater particle size distribution when the value of the mass concentration of the aerosols was kept constant. The results were used as numerical predictions of fog formation. Two dimensional observations in horizontal and vertical coordinates, together with time-dependent measurements were needed as initial values for the following physical parameters: (1)wind profiles; (2) temperature profiles; (3) humidity profiles; (4) mass concentration of aerosol particles; (5) particle size distribution of aerosols; and (6) chemical composition of aerosols. Formation and dissipation of advection fog, thus, can be forecasted numerically by introducing initial values obtained from the observations.

  19. Handling over-dispersion of performance indicators

    PubMed Central

    Spiegelhalter, D

    2005-01-01

    Objectives: A problem can arise when a performance indicator shows substantially more variability than would be expected by chance alone, since ignoring such "over-dispersion" could lead to a large number of institutions being inappropriately classified as "abnormal". A number of options for handling this phenomenon are investigated, ranging from improved risk stratification to fitting a statistical model that robustly estimates the degree of over-dispersion. Design: Retrospective analysis of publicly available data on survival following coronary artery bypass grafts, emergency readmission rates, and teenage pregnancies. Setting: NHS trusts in England. Results: Funnel plots clearly show the influence of the method chosen for dealing with over-dispersion on the "banding" a trust receives. Both multiplicative and additive approaches are feasible and give intuitively reasonable results, but the additive random effects formulation appears to have a stronger conceptual foundation. Conclusion: A random effects model may offer a reasonable solution. This method has now been adopted by the UK Healthcare Commission in their derivation of star ratings. PMID:16195568

  20. Oxidation of depleted uranium penetrators and aerosol dispersal at high temperatures

    SciTech Connect

    Elder, J.C.; Tinkle, M.C.

    1980-12-01

    Aerosols dispersed from depleted uranium penetrators exposed to air and air-CO/sub 2/ mixtures at temperatures ranging from 500 to 1000/sup 0/C for 2- or 4-h periods were characterized. These experiments indicated dispersal of low concentrations of aerosols in the respirable size range (typically <10/sup -3/% of penetrator mass at 223 cm/s (5 mph) windspeed). Oxidation was maximum at 700/sup 0/C in air and 800/sup 0/C in 50% air-50% CO/sub 2/, indicating some self-protection developed at higher temperatures. No evidence of self-sustained burning was observed, although complete oxidation can be expected in fires significantly exceeding 4 h, the longest exposure of this series. An outdoor burning experiment using 10 batches of pine wood and paper packing material as fuel caused the highest oxidation rate, probably accelerated by disruption of the oxide layer accompanying broad temperature fluctuation as each fuel batch was added.

  1. Characterization of Mojave Desert aerosols: Their effect on radiometer performance

    SciTech Connect

    Mathews, L.A.; Salgado, D.P.; Walker, P.L.

    1994-12-31

    The Antelope Valley is part of the southwestern Mojave Desert lying fifty miles north of Los Angeles International Airport. The Antelope Valley is separated from the Los Angeles and San Fernando Valley air basins by the San Gabriel Mountains. The Tehachapi Mountains, to the west, separate the Antelope Valley from the San Joaquin Valley. Combustion aerosols are transported from the San Joaquin Valley through the Tehachapi Pass and through the Soledad and Cajun passes from the Los Angeles air basin. Thus the valley`s atmosphere contains a spatially and temporally complex mixture of aerosols of urban, industrial and desert origin. The Visibility Impact Summer Study held from July to September 1990 was an intense, comprehensive study intended to measure aerosol size and chemical composition and to ascertain their optical effects. Size distributions for particle diameters from 0.01 to 10 {micro} were measured at hourly intervals and particle samplers were used to obtain chemical compositions at daily intervals at Tehachapi Pass and Edwards AFB, California. The extracted aerosol characteristics are discussed and compared to the desert aerosol model in LOWTRAN and the size and estimated composition of aerosols at China Lake reported upon earlier. The authors obtain relationships between aerosol mass and wind speed, diurnal size changes, and meteorological effects. Secondarily, extinction was calculated and used with LOWTRAN and radiosonde data for examination of aerosol effects on narrow band 3--5 and 8--12 {micro} imaging radiometer performance.

  2. MAPTIP experiment, marine aerosol properties and thermal imager performance

    SciTech Connect

    Eijk, A.M.J. van; Leeuw, G. de; Jensen, D.R.

    1994-12-31

    During the fall of 1993, a field experimental study on Marine Aerosol Properties and Thermal Imager Performance (MAPTIP) was conducted in the Dutch coastal waters. The objectives of the MAPTIP trial were: (1) to improve and validate vertical marine aerosol models by providing an extensive set of aerosol and meteorological measurements, within a coastal environment, at different altitudes and for a range of meteorological conditions; (2) to make aerosol and meteorological observations in the first 10 m above the ocean surface with a view to extending existing aerosol models to incorporate near-surface effects; (3) to assess marine boundary layer effects on thermal imaging systems. Aerosol and meteorological instruments, as well as thermal imagers and calibrated targets, were used at several platforms and locations. Measurements have been made of atmospheric turbulence and refractivity effects at wavelengths in the IR and visible, to assess the marine boundary layer effects on the degradation of thermal images. Calibrated targets at different altitudes were observed to the maximum observable range under a wide variety of conditions in both the 3--5 and 8--12 gm bands, These data will be used for the development and validation of IRST models and IR ship signature models with the view of determining the effects of marine-generated aerosols, turbulence and meteorological profiles on their performance.

  3. Evaluating Organic Aerosol Model Performance: Impact of two Embedded Assumptions

    NASA Astrophysics Data System (ADS)

    Jiang, W.; Giroux, E.; Roth, H.; Yin, D.

    2004-05-01

    Organic aerosols are important due to their abundance in the polluted lower atmosphere and their impact on human health and vegetation. However, modeling organic aerosols is a very challenging task because of the complexity of aerosol composition, structure, and formation processes. Assumptions and their associated uncertainties in both models and measurement data make model performance evaluation a truly demanding job. Although some assumptions are obvious, others are hidden and embedded, and can significantly impact modeling results, possibly even changing conclusions about model performance. This paper focuses on analyzing the impact of two embedded assumptions on evaluation of organic aerosol model performance. One assumption is about the enthalpy of vaporization widely used in various secondary organic aerosol (SOA) algorithms. The other is about the conversion factor used to obtain ambient organic aerosol concentrations from measured organic carbon. These two assumptions reflect uncertainties in the model and in the ambient measurement data, respectively. For illustration purposes, various choices of the assumed values are implemented in the evaluation process for an air quality model based on CMAQ (the Community Multiscale Air Quality Model). Model simulations are conducted for the Lower Fraser Valley covering Southwest British Columbia, Canada, and Northwest Washington, United States, for a historical pollution episode in 1993. To understand the impact of the assumed enthalpy of vaporization on modeling results, its impact on instantaneous organic aerosol yields (IAY) through partitioning coefficients is analysed first. The analysis shows that utilizing different enthalpy of vaporization values causes changes in the shapes of IAY curves and in the response of SOA formation capability of reactive organic gases to temperature variations. These changes are then carried into the air quality model and cause substantial changes in the organic aerosol modeling

  4. Simultaneous measurement of optical scattering and extinction on dispersed aerosol samples.

    PubMed

    Dial, Kathy D; Hiemstra, Scott; Thompson, Jonathan E

    2010-10-01

    Accurate and precise measurements of light scattering and extinction by atmospheric particulate matter aid understanding of tropospheric photochemistry and are required for estimates of the direct climate effects of aerosols. In this work, we report on a second generation instrument to simultaneously measure light scattering (b(scat)) and extinction (b(ext)) coefficient by dispersed aerosols. The ratio of scattering to extinction is known as the single scatter albedo (SSA); thus, the instrument is referred to as the albedometer. Extinction is measured with the well-established cavity ring-down (CRD) technique, and the scattering coefficient is determined through collection of light scattered from the CRD beam. The improved instrument allows reduction in sample volume to <1% of the original design, and a reduction in response time by a factor of >30. Through using a commercially available condensation particle counter (CPC), we have measured scattering (σ(scat)) and extinction (σ(ext)) cross sections for size-selected ammonium sulfate and nigrosin aerosols. In most cases, the measured scattering and extinction cross section were within 1 standard deviation of the accepted values generated from Mie theory suggesting accurate measurements are made. While measurement standard deviations for b(ext) and b(scat) were generally <1 Mm(-1) when the measurement cell was sealed or purged with filtered air, relative standard deviations >0.1 for these variables were observed when the particle number density was low. It is inferred that statistical fluctuations of the absolute number of particles within the probe beam leads to this effect. However, measured relative precision in albedo is always superior to that which would be mathematically propagated assuming independent measurements of b(scat) and b(ext). Thus, this report characterizes the measurement precision achieved, evaluates the potential for systematic error to be introduced through light absorption by gases

  5. HCl in rocket exhaust clouds - Atmospheric dispersion, acid aerosol characteristics, and acid rain deposition

    NASA Technical Reports Server (NTRS)

    Pellett, G. L.; Sebacher, D. I.; Bendura, R. J.; Wornom, D. E.

    1983-01-01

    Both measurements and model calculations of the temporal dispersion of peak HCl (g + aq) concentration in Titan III exhaust clouds are found to be well characterized by one-term power-law decay expressions. The respective coefficients and decay exponents, however, are found to vary widely with meteorology. The HCl (g), HCl (g + aq), dewpoint, and temperature-pressure-altitude data for Titan III exhaust clouds are consistent with accurately calculated HCl/H2O vapor-liquid compositions for a model quasi-equilibrated flat surface aqueous aerosol. Some cloud evolution characteristics are also defined. Rapid and extensive condensation of aqueous acid clearly occurs during the first three min of cloud rise. Condensation is found to be intensified by the initial entrainment of relatively moist ambient air from lower levels, that is, from levels below eventual cloud stabilization. It is pointed out that if subsequent dilution air at stabilization altitude is significantly drier, a state of maximum condensation soon occurs, followed by an aerosol evaporation phase.

  6. A collaborative European study of personal inhalable aerosol sampler performance.

    PubMed

    Kenny, L C; Aitken, R; Chalmers, C; Fabriès, J F; Gonzalez-Fernandez, E; Kromhout, H; Lidén, G; Mark, D; Riediger, G; Prodi, V

    1997-04-01

    Following the adoption of new international sampling conventions for inhalable, thoracic and respirable aerosol fractions, a working group of Comité Européen de Normalisation (CEN) drafted a standard for the performance of workplace aerosol sampling instruments. The present study was set up to verify the experimental, statistical and mathematical procedures recommended in the draft performance standard and to check that they could be applied to inhalable aerosol samplers. This was achieved by applying the tests to eight types of personal inhalable aerosol sampler commonly used for workplace monitoring throughout Europe. The study led to recommendations for revising the CEN draft standard, in order to simplify the tests and reduce their cost. However, some further work will be needed to develop simpler test facilities and methods. Several of the samplers tested were found to perform adequately with respect to the inhalable sampling convention, at least over a limited range of typical workplace conditions. In general the samplers were found to perform best in low external wind speeds, which are the test conditions thought to be closest to those normally found in indoor workplaces. The practical implementation of the CEN aerosol sampling conventions requires decisions on which sampling instruments to use, estimation of the likely impact that changing sampling methods could have on apparent exposures, and adjustment where necessary of exposure limit values. The sampler performance data obtained in this project were affected by large experimental errors, but are nevertheless a useful input to decisions on how to incorporate the CEN inhalable sampling convention into regulation, guidance and occupational hygiene practice. PMID:9155236

  7. Evaluation of a coupled dispersion and aerosol process model against measurements near a major road

    NASA Astrophysics Data System (ADS)

    Pohjola, M. A.; Pirjola, L.; Karppinen, A.; Härkönen, J.; Ketzel, M.; Kukkonen, J.

    2007-02-01

    A field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17-20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm-10 μm (aerodynamic diameter) by the Electrical Low Pressure Impactor (ELPI) and in the size range of 3-50 nm (mobility diameter) by Scanning Mobility Particle Sizer (SMPS), total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC), temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes). We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible at this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of condensable organic vapour of 1012 molecules cm-3 was shown to be in a disagreement with the measured particle size evolution, while the modelling runs with the

  8. Dispersal propensity, but not flight performance, explains variation in dispersal ability.

    PubMed

    Steyn, Vernon M; Mitchell, Katherine A; Terblanche, John S

    2016-08-17

    Enhanced dispersal ability may lead to accelerated range expansion and increased rates of population establishment, thereby affecting population genetic structure and evolutionary potential. Morphological, behavioural and physiological traits that characterize dispersive individuals from residents are poorly understood for many invertebrate systems, especially in non-polymorphic pterygote species. Here we examined phenotypic differences between dispersal-prone and philopatric individuals from repeated mark-release-recapture (MRR) experiments using an invasive agricultural pest, Ceratitis capitata Comprehensive morphometric assessment and subsequent minimal adequate modelling using an information theoretic approach identified thorax mass : body mass ratio as a key predictor of disperser flies under semi-natural conditions. Performance differences in flight ability were then examined under controlled laboratory conditions to assess whether greater thorax mass : body mass ratio was associated with enhanced flight ability. The larger thorax : body mass ratio was associated with measurable differences in mean flight duration, most predominantly in males, and also by their willingness to disperse, scored as the number and duration of voluntary flights. No other measures of whole-animal flight performance (e.g. mean and peak vertical force, total or maximum flight duration) differed. Variation in voluntary behaviour may result in significant alterations of movement behaviour and realized dispersal in nature. This phenomenon may help explain intraspecific variation in the dispersal ability of insects. PMID:27488649

  9. Performance of Desiccant Particle Dispersion Type Air Conditioning System

    NASA Astrophysics Data System (ADS)

    Hatano, Hiroyuki; Suzuki, Koichi; Kojima, Hiromitsu

    An investigation of desiccant air conditioning system is performed to demonstrate its performance in a dispersed desiccant particle systems, based on its higher gas solid contacting efficiency and isothermal dehumidification. Particle dispersion is achieved using the risers of a circulating fluidized bed, CFB, or of a pneumatic conveyer. The risers used for dehumidification are 1390 mm in height and 22 mm in diameter. The former is used to evaluate the overall dehumidification performance and the latter is used to measure the axial humidity distribution under 0.88 m/s of a superficial air velocity. Based on the results of the overall performance by changing solid loading rates, Gs, from 0.4 kg/m2s up to 6 kg/m2s, desiccant particle dispersion shows higher performance in dehumidification, while axial humidity distribution shows very rapid adsorption rate in the entrance zone of the riser. Removal of adsorption heat accelerates dehumidification rate compared to the adiabatic process.

  10. Comparison of Toxicity and Deposition of Nano-Sized Carbon Black Aerosol Prepared With or Without Dispersing Sonication

    PubMed Central

    Kang, Mingu; Han, Jeong-Hee

    2013-01-01

    Nanotoxicological research has shown toxicity of nanomaterials to be inversely related to particle size. However, the contribution of agglomeration to the toxicity of nanomaterials has not been sufficiently studied, although it is known that agglomeration is associated with increased nanomaterial size. In this study, we prepared aerosols of nano-sized carbon black by 2 different ways to verify the effects of agglomeration on the toxicity and deposition of nano-sized carbon black. The 2 methods of preparation included the carbon black dispersion method that facilitated clustering without sonication and the carbon black dispersion method involving sonication to achieve scattering and deagglomeration. Male Sprague-Dawley rats were exposed to carbon black aerosols 6 hr a day for 3 days or for 2 weeks. The median mass aerodynamic diameter of carbon black aerosols averaged 2.08 μm (for aerosol prepared without sonication; group N) and 1.79 μm (for aerosol prepared without sonication; group S). The average concentration of carbon black during the exposure period for group N and group S was 13.08 ± 3.18 mg/m3 and 13.67 ± 3.54 mg/ m3, respectively, in the 3-day experiment. The average concentration during the 2-week experiment was 9.83 ± 3.42 mg/m3 and 9.08 ± 4.49 mg/m3 for group N and group S, respectively. The amount of carbon black deposition in the lungs was significantly higher in group S than in group N in both 3-day and 2-week experiments. The number of total cells, macrophages and polymorphonuclear leukocytes in the bronchoalveolar lavage (BAL) fluid, and the number of total white blood cells and neutrophils in the blood in the 2- week experiment were significantly higher in group S than in normal control. However, differences were not found in the inflammatory cytokine levels (IL-1β, TNF-α, IL-6, etc.) and protein indicators of cell damage (albumin and lactate dehydrogenase) in the BAL fluid of both group N and group S as compared to the normal control. In

  11. Toward Uniformly Dispersed Battery Electrode Composite Materials: Characteristics and Performance.

    PubMed

    Kwon, Yo Han; Huie, Matthew M; Choi, Dalsu; Chang, Mincheol; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S; Reichmanis, Elsa

    2016-02-10

    Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches for improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. The study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials. PMID:26765041

  12. Towards uniformly dispersed battery electrode composite materials: Characteristics and performance

    DOE PAGESBeta

    Yo Han Kwon; Takeuchi, Esther S.; Huie, Matthew M.; Choi, Dalsu; Chang, Mincheol; Marschilok, Amy C.; Takeuchi, Kenneth J.; Reichmanis, Elsa

    2016-01-14

    Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches formore » improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. In conclusion, the study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials.« less

  13. Arctic aerosol and cloud measurements performed during IAOOS 2014

    NASA Astrophysics Data System (ADS)

    Mariage, Vincent; Pelon, Jacques; Blouzon, Frédéric; Geyskens, Nicolas; Amarouche, Nadir; Drezen, Christine; Calzas, Michel; Victori, Stéphane; Garracio, Magali; Desautez, Alain; Pascal, Nicolas; Foujols, Thomas; Sarkissian, Alain; Pommereau, Jean-Pierre; Sennechael, Nathalie; Provost, Christine

    2015-04-01

    Better understanding of atmosphere-ice-ocean interactions and in particular of the role of aerosols and clouds in this Earth system is of prime importance in the Arctic. In the frame of the French IAOOS Equipex project, a new observational network is planned to be developed for ocean-ice-atmosphere climate survey over the Arctic, starting in 2015, to complement satellite observations. Eye-safe lidar measurements will allow us to profile aerosols and clouds for the atmospheric part, with the objective to perform regular measurements and characterize the vertical structure and optical properties. Radiation and meteorological parameters will be measured at the surface. A first buoy has been prototyped and deployed in April 2014 at the Barneo site set by the Russian teams at the North Pole. Measurements with the first autonomous backscatter lidar ever deployed in the arctic have been taken from April to end of November 2014 before the buoy was lost. Four profiles a day have been performed allowing a good sampling of cloud variability. Observations have shown that the occurrence of low level clouds was higher than 90% during summer. The project is presented, instrument performance is described and first results are discussed.

  14. Formation of Copper Zinc Tin Sulfide Thin Films from Colloidal Nanocrystal Dispersions via Aerosol-Jet Printing and Compaction.

    PubMed

    Williams, Bryce A; Mahajan, Ankit; Smeaton, Michelle A; Holgate, Collin S; Aydil, Eray S; Francis, Lorraine F

    2015-06-01

    A three-step method to create dense polycrystalline semiconductor thin films from nanocrystal liquid dispersions is described. First, suitable substrates are coated with nanocrystals using aerosol-jet printing. Second, the porous nanocrystal coatings are compacted using a weighted roller or a hydraulic press to increase the coating density. Finally, the resulting coating is annealed for grain growth. The approach is demonstrated for making polycrystalline films of copper zinc tin sulfide (CZTS), a new solar absorber composed of earth-abundant elements. The range of coating morphologies accessible through aerosol-jet printing is examined and their formation mechanisms are revealed. Crack-free albeit porous films are obtained if most of the solvent in the aerosolized dispersion droplets containing the nanocrystals evaporates before they impinge on the substrate. In this case, nanocrystals agglomerate in flight and arrive at the substrate as solid spherical agglomerates. These porous coatings are mechanically compacted, and the density of the coating increases with compaction pressure. Dense coatings annealed in sulfur produce large-grain (>1 μm) polycrystalline CZTS films with microstructure suitable for thin-film solar cells. PMID:25989610

  15. New Products for a Better Characterisation of Smoke Plume and Gas/Aerosol Dispersion from Boreal Eurasian Forest Fires: The ALANIS Smoke Plume Project

    NASA Astrophysics Data System (ADS)

    Krol, M.; Peters, W.; Muller, J.-P.; Yershov, V.; San-Miguel, J.; Palumbo, I.; Sedano, F.; Strobl, P.; Clerbaux, C.; George, M.; Helbert, J.; Guillaume, B.

    2011-01-01

    The ALANIS (Atmosphere-LANd Integrated Study) Smoke Plume project is an on-going study funded by the ESA’s Support to Science Element (STSE) dedicated to the monitoring of the fire aerosol and trace gases dispersion over Eurasia from multi-mission EO- based data, in link with the scientific issues of land- atmosphere processes in the iLEAPS community. The injection and dispersion of the smoke plumes are performed with the TM5 model from several new products (burnt areas and forest fire emissions amounts, smoke plumes injection heights) derived from the MERIS and AATSR products and from the validated IASI CO products. A first study focused on the Russian wildfire events of the summer of 2010 has shown the potential of the European missions to assess the forest fire emissions and the aerosols/gases injection and transport over Eurasia. The release of the integrated model, including the new products still under development, is planned for the summer of 2011.

  16. Fundamental performance improvement to dispersive spectrograph based imaging technologies

    NASA Astrophysics Data System (ADS)

    Meade, Jeff T.; Behr, Bradford B.; Cenko, Andrew T.; Christensen, Peter; Hajian, Arsen R.; Hendrikse, Jan; Sweeney, Frederic D.

    2011-03-01

    Dispersive-based spectrometers may be qualified by their spectral resolving power and their throughput efficiency. A device known as a virtual slit is able to improve the resolving power by factors of several with a minimal loss in throughput, thereby fundamentally improving the quality of the spectrometer. A virtual slit was built and incorporated into a low performing spectrometer (R ~ 300) and was shown to increase the performance without a significant loss in signal. The operation and description of virtual slits is also given. High-performance, lowlight, and high-speed imaging instruments based on a dispersive-type spectrometer see the greatest impact from a virtual slit. The impact of a virtual slit on spectral domain optical coherence tomography (SD-OCT) is shown to improve the imaging quality substantially.

  17. DESIGN AND PERFORMANCE OF AN AEROSOL MASS DISTRIBUTION MONITOR

    EPA Science Inventory

    An aerosol mass monitor has been built to measure the masses of non-volatile aerosols in the range of 0.05 to 5 micrometers aerodynamic particle diameter. The instrument consists of a newly designed spiral duct aerosol centrifuge equipped with highly sensitive quartz sensors for ...

  18. Performance of 18 polymers in aluminum citrate colloidal dispersion gels

    SciTech Connect

    Smith, J.E.

    1995-11-01

    Colloidal dispersion gels are made up of low concentrations of polymer and aluminum citrate in water. These gels, which are mixed as a homogeneous solution at the surface, provide a valuable tool for in-depth blockage of high permeability regions of rock in heterogeneous reservoirs. Performance of colloidal dispersion gels depends strongly on the type and quality of polymer used. This paper provides an overview of the performance of 18 different polymers in colloidal dispersion gels. 14 of the polymers were partially hydrolyzed polyacrylamides or AMPS polymers in dry crystalline form with varying degrees of hydrolysis and molecular weight. The group also includes one cationic polyacrylamide, one carboxymethyl cellulose, one partially hydrolyzed polyacrylamide in emulsion form and one polysaccharide in dry form. Gels were mixed with the polymers at two polymer concentrations, three polymer:aluminum ratios and in different concentrations of potassium chloride. The gels were quantitatively tested at 1, 7, 14 and 28 days after crosslinking using the transition pressure test, which is a screen flow resistance test. Of the six polymer types tested, only the dry partially hydrolyzed polyacrylamides and AMPS polymers formed colloidal dispersion gels. Gel strength generally increased with increasing anionic charge and molecular weight; however, the manner in which the polymer is manufactured and the impurities present in the polymer also play roles which are more significant than originally expected.

  19. A comparison of atmospheric dispersion model predictions with observations of SO2 and sulphate aerosol from volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Heard, Imogen P. C.; Manning, Alistair J.; Haywood, James M.; Witham, Claire; Redington, Alison; Jones, Andy; Clarisse, Lieven; Bourassa, Adam

    2012-10-01

    The UK Met Office's Numerical Atmospheric-dispersion Modeling Environment (NAME) is used both operationally and for research investigations. It has previously been used to model volcanic ash at the London Volcanic Ash Advisory Centre (VAAC), including that from the eruptions in Iceland of Eyjafjallajökull in 2010 and Grímsvötn in 2011. In this paper, the ability of NAME to model the release and dispersion of volcanic SO2, the chemical processes leading to the production of sulphate aerosol, and the subsequent dispersion of sulphate aerosol, has been investigated. Sensitivity tests were carried out to investigate the suitability of the NAME chemistry scheme for use in both the troposphere and the stratosphere. The eruptions of Sarychev in 2009, Kasatochi in 2008 and Eyjafjallajökull in 2010 were simulated and results for SO2 column density and sulphate aerosol optical depth (AOD) were compared with satellite retrievals. NAME results compare favorably with available observations in terms of both geographical distribution and magnitude for all three cases. The NAME modeled values of SO2 show a correlation of 0.8 with the corresponding observations for Sarychev. Ninety percent of modeled values of northern hemisphere averaged sulphate AOD are within a factor of 2 of those observed for Kasatochi and 71% are within a factor of 2 of those observed for Sarychev. Although significant uncertainties are present in both the model and observations, this work demonstrates that NAME's current chemistry scheme shows promise as a tool for modeling SO2 and sulphate from volcanoes.

  20. Modeling long distance dispersal of airborne foot-and-mouth disease virus as a polydisperse aerosol - Application to the emergence of a new strain from Egypt to Israel

    NASA Astrophysics Data System (ADS)

    Klausner, Ziv; Klement, Eyal; Fattal, Eyal

    2015-12-01

    Long distance dispersal (LDD) of airborne aerosol of foot-and-mouth disease (FMD) virus was extensively modeled in the literature. Most studies modeled this aerosol in simplistic approach as a passive tracer, neglecting physical and biological mechanisms that affect bio-aerosols such as the FMD aerosol. This approach was justified either because under persistent wind these mechanisms lower the extant of downwind hazard or on the grounds that the effect of some of the physical mechanisms on particles as small as the FMD particles (0.015-20 μm) is supposed to be negligible compared to the effect of atmospheric turbulence. Even when the FMD aerosol was treated as aerosol, it was assumed that it is monodisperse, i.e., all its particles are of the same size. The aim of the study is to examine whether these simplistic approaches are indeed justified when dealing with LDD of a bio-aerosol under actual atmospheric conditions. In order to do so, the influence of a more realistic modeling of the FMD aerosol as a polydisperse aerosol was compared to passive tracer and to monodisperse aerosol. The comparison refers to a case of a widespread FMD outbreak that occurred in 2012 in Egypt. This outbreak involved the emergence of a new serotype in Egypt, SAT2 and concern was raised that this serotype will advance further to Asia and Europe. Israel is located on the land bridge between Africa, Asia and Europe, and shares a long desert border with Egypt as well as a long Mediterranean shore adjacent to Egypt's shore. This unique location as well as the fact that Israel does not have any cattle trade with its neighboring countries make Israel an interesting test case for the examination of the necessary conditions for the long distance dispersal (LDD) of a new FMD strains from Africa to Europe. The analysis in this study shows that under quasi-stationary wind conditions modeling FMD dispersal as a passive tracer results in a significantly longer hazard distance. Under non

  1. Effects of ramp-up of inspired airflow on in vitro aerosol dose delivery performance for certain dry powder inhalers.

    PubMed

    Ung, Keith T; Chan, Hak-Kim

    2016-03-10

    This study investigated the effect of airflow ramp-up on the dose delivery performance of seven dry powder inhalers, covering a broad range of powder formulations and powder dispersion mechanisms. In vitro performance tests were performed at a target pressure drop of 4kPa, using two inspiratory flow ramp-up conditions, representing slow and fast ramp-up of airflow, respectively. The fluidization of bulk powder and aerosol clearance from the inhaler was assessed by laser photometer evaluation of aerosol emission kinetics and measurement of the delivered dose (DD). The quality of aerosol dispersion (i.e. de-agglomeration) and associated lung targeting performance was assessed by measuring the total lung dose (TLD) using the Alberta idealized mouth-throat model. The ratio of DD and TLD under slow/fast ramp conditions was used as a metric to rank-order flow ramp effects. Test results show that the delivered dose is relatively unaffected by flow ramp (DD ratio ~1 for all dry powder inhalers). In contrast, the total lung dose showed significantly more variation as a function of flow ramp and inhaler type. Engineered (spray dried) powder formulations were associated with relatively high TLD (>50% of nominal dose) compared to lactose blend and agglomerate based formulations, which had a lower TLD (7-40% of nominal dose), indicative of less efficient targeting of the lung. The TLD for the Tobi Podhaler was the least influenced by flow ramp (TLD ratio ~1), while the TLD for the Asmanex Twisthaler was the most sensitive to flow ramp (TLD ratio ≪1). The relatively high sensitivity of the Asmanex Twisthaler to flow ramp is attributed to rapid aerosol clearance (from the inhaler) combined with a strong effect of flow-rate on particle de-agglomeration and resulting size distribution. PMID:26780380

  2. L-Leucine as an excipient against moisture on in vitro aerosolization performances of highly hygroscopic spray-dried powders.

    PubMed

    Li, Liang; Sun, Siping; Parumasivam, Thaigarajan; Denman, John A; Gengenbach, Thomas; Tang, Patricia; Mao, Shirui; Chan, Hak-Kim

    2016-05-01

    L-Leucine (LL) has been widely used to enhance the dispersion performance of powders for inhalation. LL can also protect powders against moisture, but this effect is much less studied. The aim of this study was to investigate whether LL could prevent moisture-induced deterioration in in vitro aerosolization performances of highly hygroscopic spray-dried powders. Disodium cromoglycate (DSCG) was chosen as a model drug and different amounts of LL (2-40% w/w) were added to the formulation, with the aim to explore the relationship between powder dispersion, moisture protection and physicochemical properties of the powders. The powder formulations were prepared by spray drying of aqueous solutions containing known concentrations of DSCG and LL. The particle sizes were measured by laser diffraction. The physicochemical properties of fine particles were characterized by X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic vapor sorption (DVS). The surface morphology and chemistry of fine particles were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In vitro aerosolization performances were evaluated by a next generation impactor (NGI) after the powders were stored at 60% or 75% relative humidity (RH), and 25°C for 24h. Spray-dried (SD) DSCG powders were amorphous and absorbed 30-45% (w/w) water at 70-80% RH, resulting in deterioration in the aerosolization performance of the powders. LL did not decrease the water uptake of DSCG powders, but it could significantly reduce the effect of moisture on aerosolization performances. This is due to enrichment of crystalline LL on the surface of the composite particles. The effect was directly related to the percentage of LL coverage on the surface of particles. Formulations having 61-73% (molar percent) of LL on the particle surface (which correspond to 10-20% (w

  3. Aerosol Performance and Stability of Liposomes Containing Ciprofloxacin Nanocrystals

    PubMed Central

    Wu, Huiying; Gonda, Igor; Chan, Hak-Kim

    2015-01-01

    Abstract Background: Previously we showed that the release properties of a liposomal ciprofloxacin (CFI) formulation could be attenuated by incorporation of drug nanocrystals within the vesicles. Rather than forming these drug nanocrystals during drug loading, they were created post manufacture simply by freezing and thawing the formulation. The addition of surfactant to CFI, either polysorbate 20 or Brij 30, provided an additional means to modify the release profile or incorporate an immediate-release or ‘burst’ component as well. The goal of this study was to develop a CFI formulation that retained its nanocrystalline morphology and attenuated release profile after delivery as an inhaled aerosol. Methods: Preparations of 12.5 mg/mL CFI containing 90 mg/mL sucrose and 0.1% polysorbate 20 were formulated between pH 4.6 to 5.9, stored frozen, and thawed prior to use. These thawed formulations, before and after mesh nebulization, and after subsequent refrigerated storage for up to 6 weeks, were characterized in terms of liposome structure by cryogenic transmission electron microscopy (cryo-TEM) imaging, vesicle size by dynamic light scattering, pH, drug encapsulation by centrifugation-filtration, and in vitro release (IVR) performance. Results: Within the narrower pH range of 4.9 to 5.3, these 12.5 mg/mL liposomal ciprofloxacin formulations containing 90 mg/mL sucrose and 0.1% polysorbate 20 retained their physicochemical stability for an additional 3 months refrigerated storage post freeze-thaw, were robust to mesh nebulization maintaining their vesicular form containing nanocrystalline drug and an associated slower release profile, and formed respirable aerosols with a mass median aerodynamic diameter (MMAD) of ∼3.9 μm and a geometric standard deviation (GSD) of ∼1.5. Conclusions: This study demonstrates that an attenuated release liposomal ciprofloxacin formulation can be created through incorporation of drug nanocrystals in response to freeze

  4. Assessing the Performance of Computationally Simple and Complex Representations of Aerosol Processes using a Testbed Methodology

    NASA Astrophysics Data System (ADS)

    Fast, J. D.; Ma, P.; Easter, R. C.; Liu, X.; Zaveri, R. A.; Rasch, P.

    2012-12-01

    Predictions of aerosol radiative forcing in climate models still contain large uncertainties, resulting from a poor understanding of certain aerosol processes, the level of complexity of aerosol processes represented in models, and the ability of models to account for sub-grid scale variability of aerosols and processes affecting them. In addition, comparing the performance and computational efficiency of new aerosol process modules used in various studies is problematic because different studies often employ different grid configurations, meteorology, trace gas chemistry, and emissions that affect the temporal and spatial evolution of aerosols. To address this issue, we have developed an Aerosol Modeling Testbed (AMT) to systematically and objectively evaluate aerosol process modules. The AMT consists of the modular Weather Research and Forecasting (WRF) model, a series of testbed cases for which extensive in situ and remote sensing measurements of meteorological, trace gas, and aerosol properties are available, and a suite of tools to evaluate the performance of meteorological, chemical, aerosol process modules. WRF contains various parameterizations of meteorological, chemical, and aerosol processes and includes interactive aerosol-cloud-radiation treatments similar to those employed by climate models. In addition, the physics suite from a global climate model, Community Atmosphere Model version 5 (CAM5), has also been ported to WRF so that these parameterizations can be tested at various spatial scales and compared directly with field campaign data and other parameterizations commonly used by the mesoscale modeling community. In this study, we evaluate simple and complex treatments of the aerosol size distribution and secondary organic aerosols using the AMT and measurements collected during three field campaigns: the Megacities Initiative Local and Global Observations (MILAGRO) campaign conducted in the vicinity of Mexico City during March 2006, the

  5. A two-dimensional stratospheric model of the dispersion of aerosols from the Fuego volcanic eruption

    NASA Technical Reports Server (NTRS)

    Remsberg, E. E.; Jones, C. F.; Park, J.

    1976-01-01

    Observational data of the pre- and post-volcanic aerosols from the eruption of the Volcan de Fuego in Guatemala (15 deg N) in October 1974 were used in conjunction with predictions of a 2-D circulation model to gain better understanding of the transport, chemical and sedimentation processes which determine the stratospheric aeosol layer.

  6. THE IMPACT OF BUILDING TOPOGRAPHY ON AEROSOL DISPERSION IN AN URBAN STREET CANYON

    EPA Science Inventory

    This extended abstract describes numerical simulations of the flow through a building array which includes an isolated tall tower. The work seeks to explore the impact of a single tall building on the circulation and channeling of aerosolized traffic emissions within a series of...

  7. Dispersion, efficacy, and persistence of dichlorvos aerosol against two flour beetle life stages in a mill

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The distribution, efficacy, and residual activity of dichlorvos applied as an aerosol to each of five floors of the Kansas State University pilot flour mill (9,968.8 m3 total volume) were evaluated based on responses of adults of the confused flour beetle, Tribolium confusum (Jacquelin du Val), and ...

  8. Spent fuel sabotage test program, characterization of aerosol dispersal : technical review and analysis supplement.

    SciTech Connect

    Durbin, Samuel G.; Lindgren, Eric Richard

    2009-07-01

    This project seeks to provide vital data required to assess the consequences of a terrorist attack on a spent fuel transportation cask. One such attack scenario involves the use of conical shaped charges (CSC), which are capable of damaging a spent fuel transportation cask. In the event of such an attack, the amount of radioactivity that may be released as respirable aerosols is not known with great certainty. Research to date has focused on measuring the aerosol release from single short surrogate fuel rodlets subjected to attack by a small CSC device in various aerosol chamber designs. The last series of three experiments tested surrogate fuel rodlets made with depleted uranium oxide ceramic pellets in a specially designed double chamber aerosol containment apparatus. This robust testing apparatus was designed to prevent any radioactive release and allow high level radioactive waste disposal of the entire apparatus following testing of actual spent fuel rodlets as proposed. DOE and Sandia reviews of the project to date identified a number of issues. The purpose of this supplemental report is to address and document the DOE review comments and to resolve the issues identified in the Sandia technical review.

  9. USE OF PLUME DISPERSION MODELLING FOR VIABLE AEROSOLS FROM AN ACTIVATED SLUDGE SEWAGE TREATMENT PLANT

    EPA Science Inventory

    Predictions of the emissions of airborne total viable particle (TVP) concentrations from sewage are of concern due to possible adverse human health effects. Two types of modelling approaches were explored: dispersion modelling such as the Gaussian plume dispersion model and stati...

  10. Dispersal

    USGS Publications Warehouse

    2001-01-01

    The ability of species to migrate and disperse is a trait that has interested ecologists for many years. Now that so many species and ecosystems face major environmental threats from habitat fragmentation and global climate change, the ability of species to adapt to these changes by dispersing, migrating, or moving between patches of habitat can be crucial to ensuring their survival. This book provides a timely and wide-ranging overview of the study of dispersal and incorporates much of the latest research. The causes, mechanisms, and consequences of dispersal at the individual, population, species and community levels are considered. The potential of new techniques and models for studying dispersal, drawn from molecular biology and demography, is also explored. Perspectives and insights are offered from the fields of evolution, conservation biology and genetics. Throughout the book, theoretical approaches are combined with empirical data, and care has been taken to include examples from as wide a range of species as possible.

  11. Nuclear Emergency and the Atmospheric Dispersion of Nuclear Aerosols: Discussion of the Shared Nuclear Future - 13163

    SciTech Connect

    Rana, Mukhtar A.; Ali, Nawab; Akhter, Parveen; Khan, E.U.; Mathieson, John

    2013-07-01

    This paper has a twofold objective. One is to analyze the current status of high-level nuclear waste disposal along with presentation of practical perspectives about the environmental issues involved. Present disposal designs and concepts are analyzed on a scientific basis and modifications to existing designs are proposed from the perspective of environmental safety. Other is to understand the aerosol formation in the atmosphere for the case of the leakage from the nuclear waste containers or a nuclear accident. Radio-nuclides released from the waste will attach themselves to the existing aerosols in the atmosphere along with formation of new aerosols. Anticipating the nuclear accident when a variety of radioactive aerosols will form and exist in the atmosphere, as a simple example, measurement of naturally existing radioactive aerosols are made in the atmosphere of Islamabad and Murree. A comparison with similar measurements in 3 cities of France is provided. Measurement of radionuclides in the atmosphere, their attachment to aerosols and follow up transport mechanisms are key issues in the nuclear safety. It is studied here how {sup 7}Be concentration in the atmospheric air varies in the capital city of Islamabad and a Himalaya foothill city of Murree (Pakistan). Present results are compared with recent related published results to produce a {sup 7}Be concentration versus altitude plot up to an altitude of 4000 m (a.s.l.). Origin and variance of {sup 7}Be concentration at different altitudes is discussed in detail. The relevance of results presented here with the evaluation of implications of Chernobyl and Fukushima nuclear disasters has been discussed in a conclusive manner. It is the first international report of a joint collaboration/project. The project is being generalized to investigate and formulate a smooth waste storage and disposal policy. The project will address the fission and fusion waste reduction, its storage, its recycling, air, water and soil

  12. The effectiveness of an air cleaner in controlling droplet/aerosol particle dispersion emitted from a patient's mouth in the indoor environment of dental clinics

    PubMed Central

    Chen, Chun; Zhao, Bin; Cui, Weilin; Dong, Lei; An, Na; Ouyang, Xiangying

    2010-01-01

    Dental healthcare workers (DHCWs) are at high risk of occupational exposure to droplets and aerosol particles emitted from patients' mouths during treatment. We evaluated the effectiveness of an air cleaner in reducing droplet and aerosol contamination by positioning the device in four different locations in an actual dental clinic. We applied computational fluid dynamics (CFD) methods to solve the governing equations of airflow, energy and dispersion of different-sized airborne droplets/aerosol particles. In a dental clinic, we measured the supply air velocity and temperature of the ventilation system, the airflow rate and the particle removal efficiency of the air cleaner to determine the boundary conditions for the CFD simulations. Our results indicate that use of an air cleaner in a dental clinic may be an effective method for reducing DHCWs' exposure to airborne droplets and aerosol particles. Further, we found that the probability of droplet/aerosol particle removal and the direction of airflow from the cleaner are both important control measures for droplet and aerosol contamination in a dental clinic. Thus, the distance between the air cleaner and droplet/aerosol particle source as well as the relative location of the air cleaner to both the source and the DHCW are important considerations for reducing DHCWs' exposure to droplets/aerosol particles emitted from the patient's mouth during treatments. PMID:20031985

  13. Methodologies for evaluating performance and assessing uncertainty of atmospheric dispersion models

    NASA Astrophysics Data System (ADS)

    Chang, Joseph C.

    This thesis describes methodologies to evaluate the performance and to assess the uncertainty of atmospheric dispersion models, tools that predict the fate of gases and aerosols upon their release into the atmosphere. Because of the large economic and public-health impacts often associated with the use of the dispersion model results, these models should be properly evaluated, and their uncertainty should be properly accounted for and understood. The CALPUFF, HPAC, and VLSTRACK dispersion modeling systems were applied to the Dipole Pride (DP26) field data (˜20 km in scale), in order to demonstrate the evaluation and uncertainty assessment methodologies. Dispersion model performance was found to be strongly dependent on the wind models used to generate gridded wind fields from observed station data. This is because, despite the fact that the test site was a flat area, the observed surface wind fields still showed considerable spatial variability, partly because of the surrounding mountains. It was found that the two components were comparable for the DP26 field data, with variability more important than uncertainty closer to the source, and less important farther away from the source. Therefore, reducing data errors for input meteorology may not necessarily increase model accuracy due to random turbulence. DP26 was a research-grade field experiment, where the source, meteorological, and concentration data were all well-measured. Another typical application of dispersion modeling is a forensic study where the data are usually quite scarce. An example would be the modeling of the alleged releases of chemical warfare agents during the 1991 Persian Gulf War, where the source data had to rely on intelligence reports, and where Iraq had stopped reporting weather data to the World Meteorological Organization since the 1981 Iran-Iraq-war. Therefore the meteorological fields inside Iraq must be estimated by models such as prognostic mesoscale meteorological models, based on

  14. Evaluation of the performance of the determination of anions in the water soluble fraction of atmospheric aerosols.

    PubMed

    Arias, Alejandro; Bettencourt da Silva, Ricardo J N; Camões, M Filomena G F C; Oliveira, Cristina M R R

    2013-01-30

    The knowledge of the mass of particulate matter in air, its chemical composition and emission sources is of relevance for taking decisions concerning air quality management in urban areas. The interpretation of these data is a function of the quality of the measurement results expressed by their uncertainties. This study aimed at developing models of the performance of the determination of anions in the water-soluble fraction of atmospheric aerosols, capable of determining, separately, the contribution of aerosols sampling, extraction of water-soluble fraction of atmospheric aerosols and quantification, by ion chromatography, of anions in the extract. The sampling procedure was assessed from the dispersion of results of duplicate parallel sampling after subtracting the analytical component of this dispersion. These models are used to evaluate the adequacy of the measurement procedure for the determination of urban aerosol composition and to support strategies for reducing measurement uncertainty or cost of analysis. The method performance was studied for the following ranges considering extract dilution up to five times: 0.23-8 μg m(-3) for chloride and nitrate, and 0.093-3.25 μg m(-3) for sulphate. Measurements are fit for the analysis of urban aerosols since the relative expanded measurement uncertainty is smaller than a maximum value of 40%. The percentage contribution of the uncertainty components varies with the analyte and its mass concentration, the major components being 24-93% for the extraction, 43-59% for sampling, 0.2-28% for the interpolation of the sample signal in the calibration curve and 4-8% for air volume measurement. The typical composition of analysed air is: (1.12±0.26) μg m(-3), (1.02±0.30) μg m(-3) and (0.76±0.22) μg m(-3) of chloride, nitrate and sulphate in the water soluble fraction of aerosol, respectively, for a confidence level of approximately 95% considering a coverage factor of 2. PMID:23597881

  15. Formation and performance of polymer dispersed liquid crystal films

    NASA Astrophysics Data System (ADS)

    Chan, Philip Kwok-Kiou

    Polymer dispersed liquid crystals (PDLC's) are novel composite materials consisting of micron-size liquid crystalline droplets dispersed uniformly in a solid polymer matrix. PDLC's are formed by spinodal decomposition induced by thermal quenching or polymerization. These materials have excellent magneto-optical properties, and have great potential in applications that require efficient light scattering. Present commercial applications include switchable windows for privacy control and large-scale billboards. The optical properties depend on the droplet size, shape and positional order, which are determined during the formation stage, and reorientation dynamics of the liquid crystalline molecules confined within the droplets which occurs during product use. In this thesis, new complex mathematical models that describe the formation and performance of PDLC's are successfully developed, implemented, solved and validated. The nonequilibrium thermodynamic formation model takes into account initial thermal fluctuations computed using Monte Carlo simulations and realistic arbitrary boundary conditions. The performance model is based on classical nematic liquid crystalline magneto-viscoelastic theories, and incorporates transient viscoelastic boundary conditions. The simulations are able to reproduce successfully all the experimentally observed significant dynamical and morphological features of film formation as well as all the dynamical stages observed during the use of these thin optical films. In addition, the sensitivity of the phase separating morphology to processing conditions and material parameters is elucidated. Furthermore, a new scaling method is introduced to describe the phase separation phenomena during the early and intermediate stages of spinodal decomposition induced by thermal quenching. The droplet size selection mechanism for the polymerization-induced phase separation method of forming PDLC films is identified and explained for the first time. Lastly

  16. Summary of the marine aerosol properties and thermal imager performance trial (MAPTIP). Professional paper

    SciTech Connect

    Leeuw, G. de; Eijik, A.M. van

    1995-08-01

    This paper describes a 1993 field experiment entitled Marine Aerosol Properties and Thermal Imager Performance Trial (MAPTIP) conducted by NATO AC/243 Panel 04/RSG.8 and 04/RSG.5 in the Dutch coastal waters. Objectives were: to improve and validate vertical marine aerosol models by providing an extensive set of aerosol and meteorological measurements, within a coastal environment at different altitudes and for a range of meteorological conditions; make aerosol and meteorological observations in the first 10 m of the ocean surface with a view to extending existing aerosol models to incorporate near-surface effects; and to assess marine boundary layer effects on thermal Imaging systems. Aerosol and meteorological instruments, as well as thermal imagers and calibrated targets, were utilized. This network of instrumentation has provided a comprehensive database of aerosol size distribution profiles and relevant meteorological variables throughout the marine atmospheric boundary layer. Thermal imagery was included to provide ground truth for assessing the low-level propagation effects near the ocean surface. Measurements were made of atmospheric turbulence and refractivity effects in the IR and RF bands to assess the marine boundary layer effects on the degradation of thermal images. Calibrated targets at different altitudes were observed and these data will be used for development and validation of IRST models and IR ship signature models for determining the effects of marine-generated aerosols turbulence and meteorological profiles on their performance.

  17. Measuring Performance of Energy-Dispersive X-ray Systems.

    PubMed

    Statham

    1998-11-01

    : As Si(Li) detector technology has matured, many of the fundamental problems have been addressed in the competition among manufacturers and there is now an expectation, implied by many textbooks, that all energy-dispersive X-ray (EDX) detectors are made and will perform in the same way. Although there has been some convergence in Si(Li) systems and these are still the most common, manufacturing recipes still differ and there are many alternative EDX devices, such as microcalorimeters and room temperature detectors, that have both advantages and disadvantages over Si(Li). Rather than emphasizing differences in technologies, performance measures should reveal benefits relevant to the intended application. The instrument is inevitably going to be a "black box" of integrated components; this article reviews some of the methods that have been applied and introduces some new techniques that can be used to assess performance without resorting to complex software or sophisticated mathematical algorithms. Sensitivity, resolution, artefacts, and stability are discussed with particular application to compositional analysis using electron beam excitation of X-rays in the 100-eV to 10-keV energy region. PMID:10087283

  18. Raman Lidar Measurements of Aerosol Optical Properties Performed at CNR- IMAA

    NASA Astrophysics Data System (ADS)

    Mona, L.; Amodeo, A.; Cornacchia, C.; D'Amico, G.; Madonna, F.; Pandolfi, M.; Pappalardo, G.

    2005-12-01

    The lidar system for tropospheric aerosol study, located at CNR-IMAA in Tito Scalo, Potenza (40 °36'N, 15°44' E, 760 m above sea level), is a Raman/elastic lidar system operational since May 2000 in the framework of EARLINET (European Aerosol Research LIdar NETwork), the first lidar network for tropospheric aerosol study on continental scale. It provides independent measurements of aerosol extinction and backscatter coefficient profiles at 355 nm and aerosol backscatter profiles at 532 nm. Both the IMAA aerosol lidar system and the used algorithms for the retrieval of aerosol optical parameters have been successfully tested with different intercomparison exercises in the frame of the EARLINET quality assurance program. In the frame of EARLINET, regular measurements are performed three times per week, allowing to study the aerosol content typically present in the planetary boundary layer over Potenza. Particular attention is devoted to Saharan dust intrusions in Europe, and Saharan dust forecasts are distributed to all EARLINET stations. The large dataset of Saharan dust optical properties profiles collected at IMAA allowed to study the contribution of dust particles to the aerosol load typically present in our area as well as to investigate transformations of aerosol optical properties during the transport. Several intensive measurement campaigns have been performed at IMAA with this system to study optical properties of different types of aerosol, and how the transport and modification mechanisms and the water content affect these optical properties. In particular, direct transport of volcanic aerosol emitted in 2002 during the Etna eruptions was observed, and in summer 2004, aerosol layers related to forest fires smoke or pollution plume transported from Alaska, Canada and North America were observed at IMAA during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign. Moreover, this system has been used

  19. Effect of gravitational sedimentation on simulated aerosol dispersion in the human acinus.

    PubMed

    Darquenne, Chantal; Prisk, G Kim

    2003-04-01

    We studied the effect of gravitational sedimentation on the dispersion of 0.5 and 1 micrometer-diameter particle boluses within a two-dimensional symmetric six-generation model of the human acinus. Boluses were introduced at the beginning of a 2-s inspiration immediately followed by a 4-s expiration, in normal gravity (1 G) and in the absence of gravity (0 G). The flow corresponded to a flow rate at the mouth of 500 ml/s. In 0 G, simulated dispersion (Hsim) was 16 ml for both particle sizes. In 1 G, Hsim was 71 and 242 ml for 0.5 and 1 micrometer-diameter particles, respectively, showing the effect of gravitational sedimentation. The difference between experimental data (J. Appl. Physiol. 86 (1999) 1402) and simulations was independent of particle size. This suggests that the residual dispersion was independent of the intrinsic properties of the particles and was more likely due to other mechanisms such as ventilation inhomogeneities, cardiogenic oscillations and alveolar wall motion. PMID:12747364

  20. Effect of gravitational sedimentation on simulated aerosol dispersion in the human acinus

    NASA Technical Reports Server (NTRS)

    Darquenne, Chantal; Prisk, G. Kim

    2003-01-01

    We studied the effect of gravitational sedimentation on the dispersion of 0.5 and 1 micrometer-diameter particle boluses within a two-dimensional symmetric six-generation model of the human acinus. Boluses were introduced at the beginning of a 2-s inspiration immediately followed by a 4-s expiration, in normal gravity (1 G) and in the absence of gravity (0 G). The flow corresponded to a flow rate at the mouth of 500 ml/s. In 0 G, simulated dispersion (Hsim) was 16 ml for both particle sizes. In 1 G, Hsim was 71 and 242 ml for 0.5 and 1 micrometer-diameter particles, respectively, showing the effect of gravitational sedimentation. The difference between experimental data (J. Appl. Physiol. 86 (1999) 1402) and simulations was independent of particle size. This suggests that the residual dispersion was independent of the intrinsic properties of the particles and was more likely due to other mechanisms such as ventilation inhomogeneities, cardiogenic oscillations and alveolar wall motion. c2003 Elsevier Science Ltd. All rights reserved.

  1. Design and performance measurements of an airborne aerosol backscatter lidar

    NASA Technical Reports Server (NTRS)

    Menzies, Robert T.; Tratt, David M.; Brothers, Alan M.; Dermenjian, Stephen H.; Esproles, Carlos

    1990-01-01

    The global winds measurement application of coherent Doppler lidar requires intensive study of the global climatology of atmospheric aerosol backscatter at infrared wavelengths. An airborne backscatter lidar is discussed, which has been developed to measure atmospheric backscatter profiles at CO2 laser wavelengths. The instrument characteristics and representative flight measurement results are presented.

  2. Dispersant use as a response to oil spills: toxicological effects on fish cardiac performance.

    PubMed

    Milinkovitch, Thomas; Thomas-Guyon, Hélène; Lefrançois, Christel; Imbert, Nathalie

    2013-04-01

    Dispersant use is a controversial technique used to respond to oil spills in nearshore areas. In order to assess the toxicity of this technique, this study evaluated the cardiac toxicological effects on juvenile golden grey mullets Liza aurata exposed for 48 h to either dispersant alone, chemically dispersed oil, mechanically dispersed oil, the water-soluble fraction of oil or a control condition. Following exposure, the positive inotropic effects of adrenaline were assessed in order to evaluate a potential impairment on the cardiac performance. The results revealed an impairment of the positive inotropic effects of adrenaline for all the contaminants (single dispersant, dispersed and undispersed oil, water-soluble fraction of oil). This suggests that: (1) cardiac performance is a valuable parameter to study the physiopathological effects of dispersed oil; (2) dispersant application is likely to impair cardiac performance. PMID:22976195

  3. STATISTICAL ASSESSMENT: MEASUREMENT METHODS FOR ESTIMATING PERFORMANCE OF DISPERSANTS

    EPA Science Inventory

    Crude oil and/or refined oil products accidentally released in to coastal or oceanic waters will result in the formation of surface slicks that create dispersants under appropriate conditions. owever, prior to the use of dispersants at spill sites, information regarding the perfo...

  4. Dispersion of 0.5- to 2-micron aerosol in microG and hypergravity as a probe of convective inhomogeneity in the lung.

    PubMed

    Darquenne, C; West, J B; Prisk, G K

    1999-04-01

    We used aerosol boluses to study convective gas mixing in the lung of four healthy subjects on the ground (1 G) and during short periods of microgravity (microG) and hypergravity ( approximately 1. 6 G). Boluses of 0.5-, 1-, and 2-micron-diameter particles were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 150 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The dispersion, deposition, and position of the bolus in the expired gas were calculated from these data. For each particle size, both bolus dispersion and deposition increased with Vp and were gravity dependent, with the largest dispersion and deposition occurring for the largest G level. Whereas intrinsic particle motions (diffusion, sedimentation, inertia) did not influence dispersion at shallow depths, we found that sedimentation significantly affected dispersion in the distal part of the lung (Vp >500 ml). For 0.5-micron-diameter particles for which sedimentation velocity is low, the differences between dispersion in microG and 1 G likely reflect the differences in gravitational convective inhomogeneity of ventilation between microG and 1 G. PMID:10194229

  5. Dispersion of 0.5- to 2-micron aerosol in microG and hypergravity as a probe of convective inhomogeneity in the lung

    NASA Technical Reports Server (NTRS)

    Darquenne, C.; West, J. B.; Prisk, G. K.

    1999-01-01

    We used aerosol boluses to study convective gas mixing in the lung of four healthy subjects on the ground (1 G) and during short periods of microgravity (microG) and hypergravity ( approximately 1. 6 G). Boluses of 0.5-, 1-, and 2-micron-diameter particles were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 150 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The dispersion, deposition, and position of the bolus in the expired gas were calculated from these data. For each particle size, both bolus dispersion and deposition increased with Vp and were gravity dependent, with the largest dispersion and deposition occurring for the largest G level. Whereas intrinsic particle motions (diffusion, sedimentation, inertia) did not influence dispersion at shallow depths, we found that sedimentation significantly affected dispersion in the distal part of the lung (Vp >500 ml). For 0.5-micron-diameter particles for which sedimentation velocity is low, the differences between dispersion in microG and 1 G likely reflect the differences in gravitational convective inhomogeneity of ventilation between microG and 1 G.

  6. A study of the performance of different acidic aerosol samplers and the characteristics of acidic aerosols in Hsinchu Taiwan

    SciTech Connect

    Tsai, C.J.; Perng, S.B.; Chiou, S.F.; Lin, T.Y.

    1999-07-01

    An annular denuder system (ADS), a honeycomb denuder system (HDS) and a micro-orifice uniform deposit impactor (MOUDI) were used to investigate the physical and chemical characteristics of acidic aerosols in Hsinchu Taiwan. The performances of different denuder samplers were also compared. The concentrations (in {mu}g/m{sup 3}) of major ionic species: H{sup +}, SO{sub 4}{sup 2{minus}} NO{sub 3}{sup {minus}} and NH{sub 4}{sup +} are found to average 0.019{+-}0.01 (std. dev.) (range: 0.00--0.02), 7.60{+-}5.08 (range: 1.37--16.54), 7.67{+-}5.50 (range: 1.18--21.58) and 5.27{+-}2.90 (range: 1.14--9.42), as measured by the ADS, respectively. Aerosol acidity is not severe compared to urban cities in other countries, due to neutralization of aerosol acidity by ammonia in Hsinchu. The results indicate that the size distributions of H{sup +} and NH{sub 4}{sup +} are in the single mode while those of NO{sub 3}{sup {minus}} and SO{sub 4}{sup 2{minus}} are found to be mainly bimodal. The ions such as SO{sub 4}{sup 2{minus}}, NO{sub 3}{sup {minus}}, NH{sub 4}{sup +} and H{sup +} are dominant in the fine mode, while ions such as Cl{sup {minus}}, Na{sup +} and K{sup +} are found to be in both fine and coarse modes. Comparing two different denuder samplers, the average concentration of HNO{sub 3} measured by the HDS is found to be 40% higher than that of the ADS while the average concentrations of NO{sub 3}{sup {minus}} and Cl{sup {minus}} measured by the ADS are higher than those of the HDS by 12% and 14%, respectively. The concentrations of other species are found to be similar in both denuder samplers.

  7. Characterization and performance assessment of solid dispersions prepared by hot melt extrusion and spray drying process.

    PubMed

    Agrawal, Anjali M; Dudhedia, Mayur S; Patel, Ashwinkumar D; Raikes, Michelle S

    2013-11-30

    The present study investigated effect of manufacturing methods such as hot melt extrusion (HME) and spray drying (SD) on physicochemical properties, manufacturability, physical stability and product performance of solid dispersion. Solid dispersions of compound X and PVP VA64 (1:2) when prepared by SD and HME process were amorphous by polarized light microscopy, powder X-ray diffractometry, and modulated differential scanning calorimetry analyses with a single glass transition temperature. Fourier transform infrared (FT-IR) and Raman spectroscopic analyses revealed similar molecular level interactions between compound X and PVP VA64 as evident by overlapping FT-IR and FT Raman spectra in SD and HME solid dispersions. The compactibility, tabletability, disintegration and dissolution performance were similar for solid dispersions prepared by both processing techniques. Differences in material properties such as surface area, morphological structure, powder densities, and flow characteristics were observed between SD and HME solid dispersion. The SD solid dispersion was physically less stable compared to HME solid dispersion under accelerated stability conditions. Findings from this study suggest that similar product performance could be obtained if the molecular properties of the solid dispersion processed by two different techniques are similar. However differences in material properties might affect the physical stability of the solid dispersions. PMID:24013161

  8. Skylab experiment performance evaluation manual. Appendix P: Experiment T003 inflight aerosol analysis (DOT/MSFC)

    NASA Technical Reports Server (NTRS)

    Purushotham, K. S.

    1972-01-01

    A series of analyses is presented for experiment T003, inflight aerosol analysis, to be used for evaluating the performance of the Skylab corollary experiments under preflight, inflight, and post-flight conditions. Experiment contingency plan workaround procedure and malfunction analyses are presented in order to assist in making the experiment operationally successful.

  9. Parameters influencing the aerosol capture performance of the Submerged-Bed Scrubber

    SciTech Connect

    Ruecker, C.M.; Scott, P.A.

    1987-04-01

    The Submerged-Bed Scrubber (SBS) is a novel air cleaning device that has been investigated by Pacific Northwest Laboratory (PNL) for scrubbing off gases from liquid-fed ceramic melters used to vitrify high-level waste (HLW). The concept for the SBS was originally conceived at Hanford for emergency venting of a reactor containment building. The SBS was adapted for use as a quenching scrubber at PNL because it can cool the hot melter off gas as well as remove over 90% of the airborne particles, thus meeting the minimum particulate decontamination factor (DF) of 10 required of a primary scrubber. The experiments in this study showed that the submicron aerosol DF for the SBS can exceed 100 under certain conditions. A conventional device, the ejector-venturi scrubber (EVS), has been previously used in this application. The EVS also adequately cools the hot gases from the melter while exhibiting aerosol removal DFs in the range of 5 to 30. In addition to achieving higher DFs than the EVS, however, the SBS has the advantage of being a passive system, better suited to the remote environment of an HLW processing system. The objective of this study was to characterize the performance of the SBS and to improve the aerosol capture efficiency by modifying the operating procedure or the design. A partial factorial experimental matrix was completed to determine the main effects of aerosol solubility, inlet off-gas temperature, inlet off-gas flow rate, steam-to-air ratio, bed diameter and packing diameter on the particulate removal efficiency of the SBS. Several additional experiments were conducted to measure the influence of the inlet aerosol concentration and scrubbing-water concentration on aerosol-removal performance. 33 refs., 17 figs., 14 tabs.

  10. Noise performance of phase-insensitive frequency multicasting in parametric mixer with finite dispersion.

    PubMed

    Tong, Zhi; Wiberg, Andreas O J; Myslivets, Evgeny; Huynh, Chris K; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

    2013-07-29

    Noise performance of dual-pump, multi-sideband parametric mixer operated in phase-insensitive mode is investigated theoretically and experimentally. It is shown that, in case when a large number of multicasting idlers are generated, the noise performance is strictly dictated by the dispersion characteristics of the mixer. We find that the sideband noise performance is significantly degraded in anomalous dispersion region permitting nonlinear noise amplification. In contrast, in normal dispersion region, the noise performance converges to the level of four-sideband parametric process, rather than deteriorates with increased sideband creation. Low noise generation mandates precise dispersion-induced phase mismatch among pump and sideband waves in order to control the noise coupling. We measure the noise performance improvement for a many-sideband, multi-stage mixer by incorporating new design technique. PMID:23938638

  11. Performance of smoothing by spectral dispersion (SSD) on Beamlet

    SciTech Connect

    Rothenberg, J.E.; Moran, B.; Henesian, M.; Van Wonterghem, B.

    1997-01-01

    The performance of the Beamlet laser with 1D SSD implemented is investigated. Simulations indicate that the critical issue for laser performance is the amount of additional divergence owing to SSD in comparison to the size of the spatial filter pinholes. At the current {plus_minus}200 {mu}rad pinholes used on Beamlet, simulations indicate that the levels of SSD divergence anticipated for the National Ignition Facility (NIF) results in a very slight degradation to the near field beam quality. Experiments performed with the Beamlet front end show no degradation to the near field beam with up to 100 {mu}rad of SSD divergence. Measurements of the smoothing of a far field speckle pattern generated by a phase plate show the expected improvement in contrast with increasing amounts of SSD divergence.

  12. Design, demonstration and performance of a versatile electrospray aerosol generator for nanomaterial research and applications

    NASA Astrophysics Data System (ADS)

    Jennerjohn, Nancy; Eiguren-Fernandez, Arantzazu; Prikhodko, Sergey; Fung, David C.; Hirakawa, Karen S.; Zavala-Mendez, Jose D.; Hinds, William; Kennedy, Nola J.

    2010-06-01

    Carbon nanotubes are difficult to aerosolize in a controlled manner. We present a method for generating aerosols not only of carbon nanotubes, but also of many reference and proprietary materials including quantum dots, diesel particulate matter, urban dust, and their mixtures, using electrospraying. This method can be used as a teaching tool, or as the starting point for advanced research, or to deliver nanomaterials in animal exposure studies. This electrospray system generates 180 µg of nanotubes per m3 of carrier gas, and thus aerosolizes an occupationally relevant mass concentration of nanotubes. The efficiency achievable for single-walled carbon nanotubes is 9.4%. This system is simple and quick to construct using ordinary lab techniques and affordable materials. Since it is easy to replace soiled parts with clean ones, experiments on different types of nanomaterial can be performed back to back without contamination from previous experiments. In this paper, the design, fabrication, operation and characterization of our versatile electrospray method are presented. Also, the morphological changes that carbon nanotubes undergo as they make the transition from dry powders to aerosol particles are presented.

  13. Effects of Dispersal and Initial Diversity on the Composition and Functional Performance of Bacterial Communities.

    PubMed

    Zha, Yinghua; Berga, Mercè; Comte, Jérôme; Langenheder, Silke

    2016-01-01

    Natural communities are open systems and consequently dispersal can play an important role for the diversity, composition and functioning of communities at the local scale. It is, however, still unclear how effects of dispersal differ depending on the initial diversity of local communities. Here we implemented an experiment where we manipulated the initial diversity of natural freshwater bacterioplankton communities using a dilution-to-extinction approach as well as dispersal from a regional species pool. The aim was further to test whether dispersal effects on bacterial abundance and functional parameters (average community growth rates, respiration rates, substrate utilisation ability) differ in dependence of the initial diversity of the communities. First of all, we found that both initial diversity and dispersal rates had an effect on the recruitment of taxa from a regional source, which was higher in communities with low initial diversity and at higher rates of dispersal. Higher initial diversity and dispersal also promoted higher levels of richness and evenness in local communities and affected, both, separately or interactively, the functional performance of communities. Our study therefore suggests that dispersal can influence the diversity, composition and functioning of bacterial communities and that this effect may be enhanced if the initial diversity of communities is depleted. PMID:27182596

  14. Effects of Dispersal and Initial Diversity on the Composition and Functional Performance of Bacterial Communities

    PubMed Central

    Zha, Yinghua; Berga, Mercè; Comte, Jérôme; Langenheder, Silke

    2016-01-01

    Natural communities are open systems and consequently dispersal can play an important role for the diversity, composition and functioning of communities at the local scale. It is, however, still unclear how effects of dispersal differ depending on the initial diversity of local communities. Here we implemented an experiment where we manipulated the initial diversity of natural freshwater bacterioplankton communities using a dilution-to-extinction approach as well as dispersal from a regional species pool. The aim was further to test whether dispersal effects on bacterial abundance and functional parameters (average community growth rates, respiration rates, substrate utilisation ability) differ in dependence of the initial diversity of the communities. First of all, we found that both initial diversity and dispersal rates had an effect on the recruitment of taxa from a regional source, which was higher in communities with low initial diversity and at higher rates of dispersal. Higher initial diversity and dispersal also promoted higher levels of richness and evenness in local communities and affected, both, separately or interactively, the functional performance of communities. Our study therefore suggests that dispersal can influence the diversity, composition and functioning of bacterial communities and that this effect may be enhanced if the initial diversity of communities is depleted. PMID:27182596

  15. Inhalable PEGylated Phospholipid Nanocarriers and PEGylated Therapeutics for Respiratory Delivery as Aerosolized Colloidal Dispersions and Dry Powder Inhalers

    PubMed Central

    Muralidharan, Priya; Mallory, Evan; Malapit, Monica; Hayes Jr., Don; Mansour, Heidi M.

    2014-01-01

    Nanomedicine is making groundbreaking achievements in drug delivery. The versatility of nanoparticles has given rise to its use in respiratory delivery that includes inhalation aerosol delivery by the nasal route and the pulmonary route. Due to the unique features of the respiratory route, research in exploring the respiratory route for delivery of poorly absorbed and systemically unstable drugs has been increasing. The respiratory route has been successfully used for the delivery of macromolecules like proteins, peptides, and vaccines, and continues to be examined for use with small molecules, DNA, siRNA, and gene therapy. Phospholipid nanocarriers are an attractive drug delivery system for inhalation aerosol delivery in particular. Protecting these phospholipid nanocarriers from pulmonary immune system attack by surface modification by polyethylene glycol (PEG)ylation, enhancing mucopenetration by PEGylation, and sustaining drug release for controlled drug delivery are some of the advantages of PEGylated liposomal and proliposomal inhalation aerosol delivery. This review discusses the advantages of using PEGylated phospholipid nanocarriers and PEGylated therapeutics for respiratory delivery through the nasal and pulmonary routes as inhalation aerosols. PMID:24955820

  16. Single point aerosol sampling: Evaluation of mixing and probe performance in a nuclear stack

    SciTech Connect

    Rodgers, J.C.; Fairchild, C.I.; Wood, G.O.

    1995-02-01

    Alternative Reference Methodologies (ARMs) have been developed for sampling of radionuclides from stacks and ducts that differ from the methods required by the U.S. EPA. The EPA methods are prescriptive in selection of sampling locations and in design of sampling probes whereas the alternative methods are performance driven. Tests were conducted in a stack at Los Alamos National Laboratory to demonstrate the efficacy of the ARMs. Coefficients of variation of the velocity tracer gas, and aerosol particle profiles were determined at three sampling locations. Results showed numerical criteria placed upon the coefficients of variation by the ARMs were met at sampling stations located 9 and 14 stack diameters from flow entrance, but not at a location that is 1.5 diameters downstream from the inlet. Experiments were conducted to characterize the transmission of 10 {mu}m aerodynamic equivalent diameter liquid aerosol particles through three types of sampling probes. The transmission ratio (ratio of aerosol concentration at the probe exit plane to the concentration in the free stream) was 107% for a 113 L/min (4-cfm) anisokinetic shrouded probe, but only 20% for an isokinetic probe that follows the EPA requirements. A specially designed isokinetic probe showed a transmission ratio of 63%. The shrouded probe performance would conform to the ARM criteria; however, the isokinetic probes would not.

  17. The Effect of Spacer Morphology on the Aerosolization Performance of Metered-Dose Inhalers

    PubMed Central

    Momeni, Sepideh; Nokhodchi, Ali; Ghanbarzadeh, Saeed; Hamishehkar, Hamed

    2016-01-01

    Purpose: Respiratory drug delivery has been attracted great interest for the past decades, because of the high incidence of pulmonary diseases. However, despite its invaluable benefits, there are some major drawbacks in respiratory drug delivery, mainly due to the relatively high drug deposition in undesirable regions. One way to improve the efficiency of respiratory drug delivery through metered-dose inhalers (MDI) is placing a respiratory spacer between the inhaler exit and the mouth. The aim of this study was to assess the effect of type and shape of spacer on the aerosolization performance of MDIs. Methods: A commercial Beclomethasone Dipropionate (BDP) MDI alone or equipped with two different spacer devices (roller and pear type) widely distributed in the world pharmaceutical market was used. The effect of spacers was evaluated by calculating aerosolization indexes such as fine particle fraction (FPF), mass median aerodynamic diameters (MMAD) and geometric standard deviation (GSD) using the next generation impactor. Results: Although one of the spacers resulted in superior outcomes than the other one, but it was not statistically significant. Conclusion: The results confirmed that the type and shape of spacer did not substantially influence the aerosolization performance of MDIs. PMID:27478789

  18. Single point aerosol sampling: Evaluation of mixing and probe performance in a nuclear stack

    SciTech Connect

    Rodgers, J.C.; Fairchild, C.I.; Wood, G.O.; Ortiz, C.A.; Muyshondt, A.; McFarland, A.R. |

    1994-12-31

    Alternative Reference Methodologies (ARMS) have been developed for sampling of radionuclide; from stacks and ducts that differ from the methods required by the US EPA. The EPA methods are prescriptive in selection of sampling locations and in design of sampling probes whereas the alternative methods are performance driven. Tests were conducted in a stack at Los Alamos National Laboratory to demonstrate the efficacy of the ARMS. Coefficients of variation of the velocity tracer gas, and aerosol particle profiles were determined at three sampling locations. Results showed numerical criteria placed upon the coefficients of variation by the ARMs were met at sampling stations located 9 and 14 stack diameters from flow entrance, but not at a location that is 1.5 diameters downstream from the inlet. Experiments were conducted to characterize the transmission of 10 {mu}m aerodynamic equivalent diameter liquid aerosol particles through three types of sampling probes. The transmission ratio (ratio of aerosol concentration at the probe exit plane to the concentration in the free stream) was 107% for a 113 L/min (4-cfm) an isokinetic shrouded probe, but only 20% for an isokinetic probe that follows the EPA requirements. A specially designed isokinetic probe showed a transmission ratio of 63%. The shrouded probe performance would conform to the ARM criteria; however, the isokinetic probes would not.

  19. Methods for measuring performance of vehicle cab air cleaning systems against aerosols and vapours.

    PubMed

    Bémer, D; Subra, I; Régnier, R

    2009-06-01

    Vehicle cabs equipped with an effective air cleaning and pressurization system, fitted to agricultural and off-road machineries, isolate drivers from the polluted environment, in which they are likely to work. These cabs provide protection against particulate and gaseous pollutants generated by these types of work activities. Two laboratory methods have been applied to determining the performance characteristics of two cabs of different design, namely, optical counting-based measurement of a potassium chloride (KCl) aerosol and fluorescein aerosol-based tracing. Results of cab confinement efficiency measurements agreed closely for these two methods implemented in the study. Measurements showed that high confinement efficiencies can be achieved with cabs, which are properly designed in ventilation/cleaning/airtightness terms. We also noted the importance of filter mounting airtightness, in which the smallest defect is reflected by significant degradation in cab performance. Determination of clean airflow rate by monitoring the decrease in test aerosol concentration in the test chamber gave excellent results. This method could represent an attractive alternative to methods involving gas tracing or air velocity measurement at blowing inlets. PMID:19406910

  20. Simulating the production and dispersion of environmental pollutants in aerosol phase in an urban area of great historical and cultural value.

    PubMed

    Librando, Vito; Tringali, Giuseppe; Calastrini, Francesca; Gualtieri, Giovanni

    2009-11-01

    Mathematical models were developed to simulate the production and dispersion of aerosol phase atmospheric pollutants which are the main cause of the deterioration of monuments of great historical and cultural value. This work focuses on Particulate Matter (PM) considered the primary cause of monument darkening. Road traffic is the greatest contributor to PM in urban areas. Specific emission and dispersion models were used to study typical urban configurations. The area selected for this study was the city of Florence, a suitable test bench considering the magnitude of architectural heritage together with the remarkable effect of the PM pollution from road traffic. The COPERT model, to calculate emissions, and the street canyon model coupled with the CALINE model, to simulate pollutant dispersion, were used. The PM concentrations estimated by the models were compared to actual PM concentration measurements, as well as related to the trend of some meteorological variables. The results obtained may be defined as very encouraging even the models correlated poorly: the estimated concentration trends as daily averages moderately reproduce the same trends of the measured values. PMID:18974943

  1. Development and characterization of phospholipid-stabilized submicron aqueous dispersions of coenzyme Q₁₀ presenting continuous vibrating-mesh nebulization performance.

    PubMed

    Carvalho, Thiago C; McCook, John P; Narain, Niven R; McConville, Jason T

    2013-12-01

    Coenzyme Q₁₀ (CoQ₁₀) is a poorly-water soluble compound that is being investigated for the treatment of carcinomas. The aim of this research was to develop a suitable formulation for pulmonary delivery of this anticancer agent. An appropriate selection of excipients (phospholipids) and a suitable device (Aeroneb Pro® vibrating-mesh nebulizer) were selected initially after reviewing the literature. After characterization of the bulk drug, a feasible manufacturing process was selected to obtain small particle size dispersions of CoQ₁₀. Following selection of an appropriate process, the parameters affecting drug particle size were studied. Using LD and gravimetrical analysis, nebulization was evaluated to assess the performance of the inhalation system triad: drug-excipients-device. CoQ₁₀ powder studied was crystalline with a melting point approximately at 51 °C and with a particle size of 30 µm. Microfluidization was found to be a suitable method to prepare submicron drug particles in aqueous dispersions. Increasing microfluidization processing to more than 50 passes did not provide further particle downsizing for both soya phosphatidylcholine (lecithin) and dipalmitoyl phosphatidylcholine (DPPC) dispersions of CoQ₁₀, presenting Z-average values of approximately 130 and 70 nm, respectively. Nebulization performance of lecithin-stabilized CoQ₁₀ dispersions varied according to number of passes in the microfluidizer. Formulations processed with 10 passes presented steadier nebulization over time and different rheological behavior compared to those processed with 30 or 50 passes. In conclusion, aqueous dispersions of CoQ₁₀ were adequately produced using a microfluidizer with characteristics that were suitable for pulmonary delivery with an Aeroneb Pro® nebulizer. Furthermore, the rheology of these dispersions appeared to play a significant role in the aerosol generation from the active vibrating-mesh nebulizer used. PMID:23772691

  2. Effect of crystallisation conditions and feedstock morphology on the aerosolization performance of micronised salbutamol sulphate.

    PubMed

    Shariare, M H; de Matas, M; York, P

    2011-08-30

    Salbutamol sulphate (SS) used in dry powder inhalers requires drug particles in the respirable size range of 1-5 μm to achieve a suitable therapeutic effect. The aim of this study was therefore to determine strategies for controlling drug substance characteristics pre and post-crystallisation to facilitate the production of micronised SS with desirable particle attributes for optimal delivery as an inhaled aerosol. SS batches were crystallised using an antisolvent method to produce a range of crystal morphologies. Air jet milling was then used to reduce the size of crystallised SS particles. Starting materials and micronised batches of SS were characterised in the solid state using a range of techniques with subsequent assessment of aerosol properties. Assessment of the aerodynamic characteristics of micronised SS delivered by DPI (without any carrier) indicated that fine particle fraction and emitted dose as a percentage of the total recovered dose were dependent on the quality attributes of the micronised SS, which were directly linked to the degree of imperfections and the morphology of the crystalline feedstock used in micronisation. Aerosolization performance of micronised SS can be optimised by manipulation of feedstock characteristics through crystal engineering and through definition of optimal processing conditions for micronisation. PMID:21683128

  3. Effects of formulation and operating variables on zanamivir dry powder inhalation characteristics and aerosolization performance.

    PubMed

    Yang, Yang; Yang, Ziwei; Ren, Yufeng; Mei, Xingguo

    2014-09-01

    Abstract The objective of this study was to investigate the influence of formulation and operating variables on the physical characteristics and aerosolization performance of zanamivir spary-dried powders for inhalation. Spray-dried samples of zanamivir, zanamivir/mannitol and zanamivir/mannitol/leucine were prepared from their corresponding aqueous solutions under the same conditions to study the influence of the composition, and zanamivir/mannitol/leucine (1/1/3 by weight) formulation was used for investigation of the effect of the preparation process. Dry powders were characterized afterwards for different physical properties, including morphology, particle size, flowability, density and moisture absorption. The in vitro deposition was also evaluated after the aerosolization of powders at 100 L min(-1) via the Aerolizer® into a Next Generation Impactor (NGI). The highest FPF of 41.40 ± 1.1% was obtained with a zanamivir/mannitol/leucine ratio of 1/1/3, which had an average Dg of 3.11 ± 0.13 μm and an angle of repose of 36°( )± 1. It was found that the influence of the preparation process on zanamivir spary-dried powders characteristics and aerosolization properties was relatively small, but the influence of the composition was relatively large. Optimization of DPI can be achieved by selecting the most appropriate formulation and preparation process. PMID:24491208

  4. Performance of the Lidar Design and Data Algorithms for the GLAS Global Cloud and Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D.; Palm, Stephen P.; Hlavka, Dennis L.; Hart, William D.

    2007-01-01

    The Geoscience Laser Altimeter System (GLAS) launched in early 2003 is the first polar orbiting satellite lidar. The instrument design includes high performance observations of the distribution and optical scattering cross sections of atmospheric clouds and aerosol. The backscatter lidar operates at two wavelengths, 532 and 1064 nm. For the atmospheric cloud and aerosol measurements, the 532 nm channel was designed for ultra high efficiency with solid state photon counting detectors and etalon filtering. Data processing algorithms were developed to calibrate and normalize the signals and produce global scale data products of the height distribution of cloud and aerosol layers and their optical depths and particulate scattering cross sections up to the limit of optical attenuation. The paper will concentrate on the effectiveness and limitations of the lidar channel design and data product algorithms. Both atmospheric receiver channels meet and exceed their design goals. Geiger Mode Avalanche Photodiode modules are used for the 532 nm signal. The operational experience is that some signal artifacts and non-linearity require correction in data processing. As with all photon counting detectors, a pulse-pile-up calibration is an important aspect of the measurement. Additional signal corrections were found to be necessary relating to correction of a saturation signal-run-on effect and also for daytime data, a small range dependent variation in the responsivity. It was possible to correct for these signal errors in data processing and achieve the requirement to accurately profile aerosol and cloud cross section down to 10-7 llm-sr. The analysis procedure employs a precise calibration against molecular scattering in the mid-stratosphere. The 1064 nm channel detection employs a high-speed analog APD for surface and atmospheric measurements where the detection sensitivity is limited by detector noise and is over an order of magnitude less than at 532 nm. A unique feature of

  5. Dispersion of UO{sub 2}F{sub 2} aerosol and HF vapor in the operating floor during winter ventilation at the Paducah Gaseous Diffusion Plant

    SciTech Connect

    Kim, S.H.; Chen, N.C.J.; Taleyarkhan, R.P.; Keith, K.D.; Schmidt, R.W.; Carter, J.C.

    1996-12-30

    The gaseous diffusion process is currently employed at two plants in the US: the Paducah Gaseous Diffusion Plant and the Portsmouth Gaseous Diffusion Plant. As part of a facility-wide safety evaluation, a postulated design basis accident involving large line-rupture induced releases of uranium hexafluoride (UF{sub 6}) into the process building of a gaseous diffusion plant (GDP) is evaluated. When UF{sub 6} is released into the atmosphere, it undergoes an exothermic chemical reaction with moisture (H{sub 2}O) in the air to form vaporized hydrogen fluoride (HF) and aerosolized uranyl fluoride (UO{sub 2}F{sub 2}). These reactants disperse in the process building and transport through the building ventilation system. The ventilation system draws outside air into the process building, distributes it evenly throughout the building, and discharges it to the atmosphere at an elevated temperature. Since air is recirculated from the cell floor area to the operating floor, issues concerning in-building worker safety and evacuation need to be addressed. Therefore, the objective of this study is to evaluate the transport of HF vapor and UO{sub 2}F{sub 2} aerosols throughout the operating floor area following B-line break accident in the cell floor area.

  6. Dispersion and transport of tropospheric aerosol and pollutants in the Western Mediterranean: the role of the Po Valley under different transport regimes

    NASA Astrophysics Data System (ADS)

    Bucci, Silvia; Fierli, Federico; Ravetta, François; Raut, Jean Christophe; Cristofanelli, Paolo; Decesari, Stefano; Diliberto, Luca; Größ, Johannes; Pap, Ines; Weinhold, Kay; Wiedensohler, Alfred; Cairo, Francesco

    2016-04-01

    This work reports a characterization of the vertical variability of tropospheric aerosol and gaseous pollutants, over the western Mediterranean, during the 2012 summer season. In particular, we investigate the role of the Po Valley region as a receptor and emissive region of both natural and anthropogenic aerosol. The observational analysis, based on a comprehensive database of meteorological, aerosol and chemical measurements, is integrated with a model analysis using the Lagrangian transport system FLEXPART combined with emission databases, and WRF-Chem, the Weather Research and Forecasting (WRF) model coupled with Chemistry. Observations have been performed in the framework of the Supersito project by Regional Agency of Prevention and Environment of the Emilia Romagna region (ARPA-ER, Ital), the TRAQA campaign (TRAnsport et Qualité de l'Air au dessus du bassin Méditerranéen) performed in the ChArMEx (Chemistry-Aerosol Mediterranean Experiment) project, and the european project PEGASOS (Pan-European Gas-AeroSOl-climate interaction Study). An alternation between different transport regimes characterized the 2012 summer, resulting in a large variability of aerosol and pollution at different time and spatial scales. Particles of different nature have been discriminated basing on optical properties retrieved from lidar data and supported by in-situ observations and transport analysis. Results show that, during the analysed season, aerosol in the Po Valley was mainly confined below 2000 m and dominated (50% of detections) by spherical particles. Two events of dust advection from northern Africa were identified (19th-21th June and 29th June-2nd July), with intrusion and mixing with local pollution in the PBL and a non-negligible occurrence (~7%) of dust at the ground. Frequent events (22% of occurrence) of non-spherical particles resuspension, likely due to uplift of mineral soil particles, were observed from the ground to 2000 m during afternoon and evening. In the

  7. Polymer coating of carrier excipients modify aerosol performance of adhered drugs used in dry powder inhalation therapy.

    PubMed

    Traini, Daniela; Scalia, Santo; Adi, Handoko; Marangoni, Elisabetta; Young, Paul M

    2012-11-15

    The potential of excipient coating to enhance aerosol performance of micronized drugs in carrier excipient-drug blends, used in dry powder inhalers, was investigated. Both EC (ethyl cellulose) and PVP (polyvinylpyrrolidone) were used as coating agents. Carriers were prepared via sieve fractioning followed by spray drying, with and without polymer additive. Each uncoated and coated carrier salbutamol sulphate (SS) blended systems were evaluated for particle size, morphology, drug carrier adhesion and aerosolisation performance, after blending and storage for 24h. All carrier-based systems prepared had similar particle sizes and morphologies. The surface chemistries of the carriers were significantly different, as was drug-carrier adhesion and aerosolisation performance. Particle adhesion between SS and aerosol performance (fine particle fraction; FPF) followed the rank: PVP coated>un-coated>EC coated lactose. This rank order could be attributed to the surface energy measured by contact goniometry and related to the chemistry of lactose and each polymer. Storage did not significantly affect aerosol performance, however a rank increase in mean FPF value was observed for uncoated and EC coated lactose. Finally, the net electrostatic charge across the aerosol cloud indicated that the EC coated lactose transferred less charge to SS particles. The performance of each carrier system could be attributed to the carrier surface chemistry and, in general, by careful selection of the coating polymer, drug-carrier adhesion, electrostatic charge and aerosol performance could be controlled. PMID:22964399

  8. Itraconazole/TPGS/Aerosil200 solid dispersions: characterization, physical stability and in vivo performance.

    PubMed

    Van Eerdenbrugh, Bernard; Van Speybroeck, Michiel; Mols, Raf; Houthoofd, Kristof; Martens, Johan A; Froyen, Ludo; Van Humbeeck, Jan; Augustijns, Patrick; Van den Mooter, Guy

    2009-10-01

    Solid dispersions were successfully prepared by co-spray-drying of TPGS-stabilized itraconazole nanosuspensions with Aerosil200, followed by heat treatment of the powders. The itraconazole/Aerosil200 weight ratios amounted to 50/50, 30/70, 40/60 and 20/80. The itraconazole content of the powders was close to the expected value, with relative errors between 0.3% and 7.8%. X-ray powder diffraction (XRPD), solid state NMR (SSNMR) and differential scanning calorimetry (DSC) evaluation on the powders revealed the formation of amorphous itraconazole and the absence of glassy itraconazole. Dissolution of the powders was enhanced compared to crystalline and glassy itraconazole (a 2-dimensional structured form of itraconazole). However, no clear trend could be observed between drug loading and dissolution performance of the solid dispersions. Upon storage, conversion to crystalline itraconazole was observed for the 50/50 powder based on XRPD, SSNMR and DSC measurements. Although the 40/60 powder remained X-ray amorphous upon storage, DSC did reveal that a small fraction (7.5+/-1.6% after 10 months of storage) of itraconazole crystallized upon storage. For the 30/70 and 20/80 dispersions, no crystallization could be seen. After 10 months of storage, important changes in the dissolution behavior of the powders were observed. A decrease in dissolution performance was seen for the 50/50 dispersion, which could be attributed to the crystallization of itraconazole. On the other hand, the 40/60, 30/70 and 20/80 dispersions showed an increase in dissolution rate (more than 60% after 10 min). Although not completely clear at this stage, adsorption of itraconazole onto the Aerosil200 surface during storage might be responsible for this behavior. Finally, in vivo experiments were performed in the rat. Oral bioavailability of the 30/70 dispersion was, although lower compared to the marketed Sporanox formulation, significantly enhanced compared to the crystalline drug. PMID:19686846

  9. A new paradigm in respiratory hygiene: increasing the cohesivity of airway secretions to improve cough interaction and reduce aerosol dispersion

    PubMed Central

    Zayas, Gustavo; Dimitry, John; Zayas, Ana; O'Brien, Darryl; King, Malcolm

    2005-01-01

    Background Infectious respiratory diseases are transmitted to non-infected subjects when an infected person expels pathogenic microorganisms to the surrounding environment when coughing or sneezing. When the airway mucus layer interacts with high-speed airflow, droplets are expelled as aerosol; their concentration and size distribution may each play an important role in disease transmission. Our goal is to reduce the aerosolizability of respiratory secretions while interfering only minimally with normal mucus clearance using agents capable of increasing crosslinking in the mucin glycoprotein network. Methods We exposed mucus simulants (MS) to airflow in a simulated cough machine (SCM). The MS ranged from non-viscous, non-elastic substances (water) to MS of varying degrees of viscosity and elasticity. Mucociliary clearance of the MS was assessed on the frog palate, elasticity in the Filancemeter and the aerosol pattern in a "bulls-eye" target. The sample loaded was weighed before and after each cough maneuver. We tested two mucomodulators: sodium tetraborate (XL"B") and calcium chloride (XL "C"). Results Mucociliary transport was close to normal speed in viscoelastic samples compared to non-elastic, non-viscous or viscous-only samples. Spinnability ranged from 2.5 ± 0.6 to 50.9 ± 6.9 cm, and the amount of MS expelled from the SCM increased from 47 % to 96 % adding 1.5 μL to 150 μL of XL "B". Concurrently, particles were inversely reduced to almost disappear from the aerosolization pattern. Conclusion The aerosolizability of MS was modified by increasing its cohesivity, thereby reducing the number of particles expelled from the SCM while interfering minimally with its clearance on the frog palate. An unexpected finding is that MS crosslinking increased "expectoration". PMID:16138926

  10. Thirty month variability of aerosol pulse dispersion and conventional lung function parameters in healthy middle aged smokers and nonsmokers.

    PubMed

    Siekmeier, R; Schiller-Scotland, C F; Stahlhofen, W

    1996-11-01

    Chronic cigarette consumption is a generally accepted reason for the development of chronic obstructive pulmonary disease (COPD). COPD correlates to histomorphological parameters of lung structure as well as pulmonary function tests (PFT). COPD related changes affect PFT determined by conventional methods (bodyplethysmography, spirometry) as well as parameters of convective gas mixing. This study evaluates the diagnostic potential of a non-invasive aerosol method for the discrimination between healthy smokers and nonsmokers in comparison to conventional PFT. The aerosol method is based on the inhalation of small aerosol pulses suspended in particle free air and determines their changes during the breathing maneuver. Changes of aerosol pulse parameters (APP) are used to describe the convective component of gas mixing during ventilation. PFT and APP were determined in 40 healthy subjects (nonsmoker: 51.1 +/- 1.5 years; smoker: 49.6 +/- 1.5 years, 39.1 +/- 2.2 pack years) before and after a time interval of 30 months. Conventional PFT in smokers and nonsmokers showed no relevant differences between the values at the beginning and the end of the observation period. Thirty months later, at the end of the observation interval, a very similar behavior of the APP was obtained, which strongly confirmed the prior observed differences between smokers and nonsmokers. The data suggest that cigarette smoke-induced variations of lung function are also detectable in clinically asymptomatic smokers. Even in cases of normal PFT, most APP are able to discriminate between healthy smokers and nonsmokers. Since PFT showed only minor differences between both groups, it is indicated that APP are superior to PFT in the detection of early disturbances of lung ventilation in healthy smokers. Mean values of PFT and APP in smokers and nonsmokers showed a high reproducibility of the data obtained at the beginning of the study as well as at the end of the observation period. The data of our

  11. Effects of Fiber Dispersion on the Performance of Optical CDMA Systems

    NASA Astrophysics Data System (ADS)

    Kharazi, Seyed Mohammad Saleh Seyedzadeh; Mahdiraji, Ghafour Amouzad; Sahbudin, Ratna Kalos Zakiah; Abas, Ahmad Fauzi; Anas, Siti Barirah Ahmad

    2012-12-01

    In recent years, Optical Code Division Multiple Access (OCDMA) system had received great attentions due to its potential to support applications with various data rates and Quality of Service requirements in physical layer. Since the main part of any fiber-based transmission system is the optical fiber itself, OCDMA also suffers from fiber impairments especially dispersion. In this paper, a review of fiber dispersion effects on system performance of different coding techniques is presented, focusing on single mode fiber. The different coding techniques include direct-sequence, spectral amplitude encoding and wavelength hopping/time spreading. In addition, the basic dispersion compensation approaches, which have been proposed in the literature, for these particular coding schemes are also discussed.

  12. Performance of an improved monodisperse aerosol generation interface for liquid chromatography/mass spectrometry

    SciTech Connect

    Winkler, P.C.; Perkins, D.D.; Williams, W.K.; Browner, R.F.

    1988-03-01

    An improved monodisperse aerosol generation interface for liquid chromatography/mass spectrometry interfacing (MAG-IC-LC/MS) is described. The interface has an aerodynamically superior momentum separator, which results in decreased analyte loss in passing through the interface. The interface is shown to perform well with a quadrupole mass spectrometer, in addition to earlier studies with a magnetic sector instrument. A new method of forming aerosol has been developed, which reduces the dead volume significantly over earlier designs. The performance of the interface has been evaluated by studying its capabilities for (1) generating electron impact spectra of searchable quality for selected compounds of interest, (2) operating with typical liquid chromatographic separation conditions, including reverse phase and gradient elution, and (3) providing low detection limits for both full scan and selective ion monitoring detection of a range of compounds. Studies include identification of the components of a mixture of cis and trans isomers of the thermally labile compound retinol (vitamin A) acetate. Full scan (m/z 80-350) electron impact spectra were readily obtained with 50-ng injection on-column. Detection limits for this compound were 10 ng full scan and 1 ng with selected ion monitoring. Identification of a free (nonderivatized) fatty acid mixture was also readily obtained, using a reversed-phase separation in gradient mode.

  13. The design of an aerosol test tunnel for occupational hygiene investigations

    NASA Astrophysics Data System (ADS)

    Blackford, D. B.; Heighington, K.

    An aerosol test tunnel which provides large working sections is described and its performance evaluated. Air movement within the tunnel is achieved with a powerful D.C. motor and centrifugal fan. Test dusts are dispersed and injected into the tunnel by means of an aerosol generator. A unique divertor valve allows aerosol laden air to be either cleaned by a commercial pulse jet filtration unit or recycled around the tunnel to obtain a high aerosol concentration. The tunnel instrumentation is managed by a microcomputer which automatically controls the airspeed and aerosol concentration.

  14. Performance evaluation of modified Semi-continuous Elements in Aerosol Sampler-III

    NASA Astrophysics Data System (ADS)

    Pancras, Joseph Patrick; Landis, Matthew S.

    2011-12-01

    A field study was conducted to evaluate the performance of a Semi-continuous Elements in Aerosol Sampler-III (SEAS-III), designed to collect ambient PM 2.5 aerosol samples at a time resolution of 30 min for elemental concentration measurements. Two identical but modified SEAS-III samplers were operated for four continuous weeks in Dearborn, MI, during July-August 2007. A total of 2308 samples were collected from the two samplers. Sampling completeness from the primary and duplicate samplers was 90% and 84%, respectively. All of the collected samples were analyzed for dilute acid-extractable trace metal concentrations using HR-ICPMS. A total of 878 collection time-matched sample pairs were available to evaluate whole-system uncertainty from collocated concentration measurements. The collocated precision for the 27 studied elements (Al, As, Ba, Ca, Cd, Ce, Cs, Cu, Fe, Ge, K, La, Mg, Mn, Mo, Na, P, Pb, Rb, S, Sb, Se, Sn, Sr, Ti, V, and Zn) varied between 9% and 40%. Twenty elements showed precision better than 25%. Uncertainty estimates from propagation of errors compared well with the whole-system uncertainty values for all minor aerosol elements studied. SEAS-III measurements of As, Cd, Ge, K, La, Mn, Mo, Na, Rb, Se, Sb, Sr, Ti, V, and Zn correlated well ( r > 0.8) with a FRM equivalent PM 2.5 integrated filter sampling method. Based on these measurements, collection efficiency of SEAS-III was estimated to be 87 ± 16%. Solubility of particles in the collection medium (water) was identified as a possible reason for low recovery of Al, Fe, Pb, Sb, and Sn.

  15. Optical measurement of medical aerosol media parameters

    NASA Astrophysics Data System (ADS)

    Sharkany, Josif P.; Zhytov, Nikolay B.; Sichka, Mikhail J.; Lemko, Ivan S.; Pintye, Josif L.; Chonka, Yaroslav V.

    2000-07-01

    The problem of aerosol media parameters measurements are presented in the work and these media are used for the treatment of the patients with bronchial asthma moreover we show the results of the development and the concentration and dispersity of the particles for the long-term monitoring under such conditions when the aggressive surroundings are available. The system for concentration measurements is developed, which consists of two identical photometers permitting to carry out the measurements of the transmission changes and the light dispersion depending on the concentration of the particles. The given system permits to take into account the error, connected with the deposition of the salt particles on the optical windows and the mirrors in the course of the long-term monitoring. For the controlling of the dispersity of the aggressive media aerosols the optical system is developed and used for the non-stop analysis of the Fure-spectra of the aerosols which deposit on the lavsan film. The registration of the information is performed with the help of the rule of the photoreceivers or CCD-chamber which are located in the Fure- plane. With the help of the developed optical system the measurements of the concentration and dispersity of the rock-salt aerosols were made in the medical mines of Solotvino (Ukraine) and in the artificial chambers of the aerosol therapy.

  16. Elastic-resilience-induced dispersion of carbon nanotubes: a novel way of fabricating high performance elastomer

    NASA Astrophysics Data System (ADS)

    Wu, Siwu; Lin, Tengfei; Guo, Baochun

    2013-11-01

    State-of-the-art processes cannot achieve rubber/multi-walled carbon nanotube (MWCNT) composites with satisfactory performance by using pristine MWCNTs and conventional processing equipment. In this work, high performance rubber/MWCNT composites featuring a combination of good mechanical properties, electrical and thermal conductivities and damping capacity over a wide temperature range are fabricated based on a well-developed master batch process. It is demonstrated that the MWCNTs are dispersed homogeneously due to the disentanglement induced by well-wetting and shearing, and the elastic-resilience-induced dispersion of the MWCNTs by rubber chains via the novel processing method. To further enhance the efficacy of elastic-resilience-induced dispersion for MWCNTs, a slightly pre-crosslinked network is constructed in the master batch. Consequently, we obtain rubber/MWCNT composites with unprecedented performance by amplifying the reinforcing effect of relatively low MWCNT loading. This work provides a novel insight into the fabrication of high performance functional elastomeric composites with pristine CNTs by taking advantage of the unique elastic resilience of rubber chains as the driving force for the disentanglement of CNTs.

  17. Elastic-resilience-induced dispersion of carbon nanotubes: a novel way of fabricating high performance elastomer.

    PubMed

    Wu, Siwu; Lin, Tengfei; Guo, Baochun

    2013-11-22

    State-of-the-art processes cannot achieve rubber/multi-walled carbon nanotube (MWCNT) composites with satisfactory performance by using pristine MWCNTs and conventional processing equipment. In this work, high performance rubber/MWCNT composites featuring a combination of good mechanical properties, electrical and thermal conductivities and damping capacity over a wide temperature range are fabricated based on a well-developed master batch process. It is demonstrated that the MWCNTs are dispersed homogeneously due to the disentanglement induced by well-wetting and shearing, and the elastic-resilience-induced dispersion of the MWCNTs by rubber chains via the novel processing method. To further enhance the efficacy of elastic-resilience-induced dispersion for MWCNTs, a slightly pre-crosslinked network is constructed in the master batch. Consequently, we obtain rubber/MWCNT composites with unprecedented performance by amplifying the reinforcing effect of relatively low MWCNT loading. This work provides a novel insight into the fabrication of high performance functional elastomeric composites with pristine CNTs by taking advantage of the unique elastic resilience of rubber chains as the driving force for the disentanglement of CNTs. PMID:24164916

  18. Performance of Dispersed Fringe Sensor in the Presence of Segmented Mirror Aberrations: Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Shi, Fang; Basinger, Scott A.; Redding, David C.

    2006-01-01

    Dispersed Fringe Sensing (DFS) is an efficient and robust method for coarse phasing of a segmented primary mirror such as the James Webb Space Telescope (JWST). In this paper, modeling and simulations are used to study the effect of segmented mirror aberrations on the fringe image, DFS signals and DFS detection accuracy. The study has shown due to the pixilation spatial filter effect from DFS signal extraction the effect of wavefront error is reduced and DFS algorithm will be more robust against wavefront aberration by using multi-trace DFS approach. We also studied the JWST Dispersed Hartmann Sensor (DHS) performance in presence of wavefront aberrations caused by the gravity sag and we use the scaled gravity sag to explore the JWST DHS performance relationship with the level of the wavefront aberration. This also includes the effect from line-of-sight jitter.

  19. Characterization of individual submicrometer aerosol particles collected in Incheon, Korea, by quantitative transmission electron microscopy energy-dispersive X-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Geng, Hong; Kang, Sujin; Jung, Hae-Jin; ChoëL, Marie; Kim, Hyekyeong; Ro, Chul-Un

    2010-08-01

    For the last decade the Monte Carlo calculation method has been proven to be an excellent tool for accurately simulating electron-solid interactions in atmospheric individual particles of micrometer size. Although it was designed for application to scanning electron microscopy, in the present study it is demonstrated that the Monte Carlo calculation can also be applied in a quantitative single particle analysis using transmission electron microscopy (TEM) with an ultrathin window energy-dispersive X-ray (EDX) spectrometer with a high accelerating voltage (200 kV). By utilizing an iterative reverse Monte Carlo simulation combined with successive approximation, atomic elemental concentrations (including low-Z elements) of submicrometer standard particles were determined with high accuracy for electron beam refractory particles such as NaCl, KCl, SiO2, Fe2O3, Na2SO4, K2SO4, CaCO3, and CaSO4. On the basis of quantitative X-ray analysis together with morphological information from TEM images, overall 1638 submicrometer individual particles from 10 sets of aerosol samples collected in Incheon, Korea, were identified. The most frequently encountered particle types are carbonaceous and (NH4)2SO4/NH4HSO4-containing particles, followed by mineral (e.g., aluminosilicate, SiO2, CaCO3), sea salt, K-rich (e.g., K2SO4 and KCl), Fe-rich, fly ash, and transition or heavy-metal-containing (e.g., ZnSO4, ZnCl2, PbSO4) particles. The relative abundances of the submicrometer particle types vary among samples collected in different seasons and also depend on different air mass transport routes. This study demonstrates that the quantitative TEM-EDX individual particle analysis is a useful and reliable technique in characterizing urban submicrometer aerosol particles.

  20. Post irradiation analysis and performance modeling of dispersion and monolithic U-Mo fuels

    SciTech Connect

    Kim, Yeon Soo; Hofman, G.L.; Medvedev, P.G.; Robinson, A.B.; Shevlyakov, G.V.; Ryu, H.J.

    2008-07-15

    We analyzed fission product swelling of post-irradiation U-Mo fuels from the early RERTR tests to the recent RERTR-8 test. We found that the gas bubble swelling of the fuel-swelling model was overestimated. From the recent tests, RERTR-7A and 8, we could also collect a considerable amount of fuel swelling data from monolithic U-Mo fuel plates. The fuel swelling data from the monolithic fuel plates are considered more reliable because the interaction layer growth between the fuel and matrix in dispersion fuel, which obscures fuel swelling, does not exist. The swelling correlation comparison to the Si-added dispersion fuel data and monolithic fuel data suggested that a modification of the existing model was necessary. We also developed an interaction layer growth model for U-Mo/Al dispersion fuel plates with a Si-added matrix. PLATE code calculations with the new PIE data analysis results were performed. The updated versions predict with better accuracies for both monolithic fuel plates and dispersion fuel plates. In this paper, we present the results of fission product swelling characterization. In addition, the interaction layer growth model for U-Mo/Al with a Si-added matrix is presented. (author)

  1. Direct comparison of shot-to-shot noise performance of all normal dispersion and anomalous dispersion supercontinuum pumped with sub-picosecond pulse fiber-based laser

    NASA Astrophysics Data System (ADS)

    Klimczak, Mariusz; Soboń, Grzegorz; Kasztelanic, Rafał; Abramski, Krzysztof M.; Buczyński, Ryszard

    2016-01-01

    Coherence of supercontinuum sources is critical for applications involving characterization of ultrafast or rarely occurring phenomena. With the demonstrated spectral coverage of supercontinuum extending from near-infrared to over 10 μm in a single nonlinear fiber, there has been a clear push for the bandwidth rather than for attempting to optimize the dynamic properties of the generated spectrum. In this work we provide an experimental assessment of the shot-to-shot noise performance of supercontinuum generation in two types of soft glass photonic crystal fibers. Phase coherence and intensity fluctuations are compared for the cases of an anomalous dispersion-pumped fiber and an all-normal dispersion fiber. With the use of the dispersive Fourier transformation method, we demonstrate that a factor of 100 improvement in signal-to-noise ratio is achieved in the normal-dispersion over anomalous dispersion-pumped fiber for 390 fs long pump pulses. A double-clad design of the photonic lattice of the fiber is further postulated to enable a pump-related seeding mechanism of normal-dispersion supercontinuum broadening under sub-picosecond pumping, which is otherwise known for similar noise characteristics as modulation instability driven, soliton-based spectra.

  2. Direct comparison of shot-to-shot noise performance of all normal dispersion and anomalous dispersion supercontinuum pumped with sub-picosecond pulse fiber-based laser

    PubMed Central

    Klimczak, Mariusz; Soboń, Grzegorz; Kasztelanic, Rafał; Abramski, Krzysztof M.; Buczyński, Ryszard

    2016-01-01

    Coherence of supercontinuum sources is critical for applications involving characterization of ultrafast or rarely occurring phenomena. With the demonstrated spectral coverage of supercontinuum extending from near-infrared to over 10 μm in a single nonlinear fiber, there has been a clear push for the bandwidth rather than for attempting to optimize the dynamic properties of the generated spectrum. In this work we provide an experimental assessment of the shot-to-shot noise performance of supercontinuum generation in two types of soft glass photonic crystal fibers. Phase coherence and intensity fluctuations are compared for the cases of an anomalous dispersion-pumped fiber and an all-normal dispersion fiber. With the use of the dispersive Fourier transformation method, we demonstrate that a factor of 100 improvement in signal-to-noise ratio is achieved in the normal-dispersion over anomalous dispersion-pumped fiber for 390 fs long pump pulses. A double-clad design of the photonic lattice of the fiber is further postulated to enable a pump-related seeding mechanism of normal-dispersion supercontinuum broadening under sub-picosecond pumping, which is otherwise known for similar noise characteristics as modulation instability driven, soliton-based spectra. PMID:26759188

  3. Direct comparison of shot-to-shot noise performance of all normal dispersion and anomalous dispersion supercontinuum pumped with sub-picosecond pulse fiber-based laser.

    PubMed

    Klimczak, Mariusz; Soboń, Grzegorz; Kasztelanic, Rafał; Abramski, Krzysztof M; Buczyński, Ryszard

    2016-01-01

    Coherence of supercontinuum sources is critical for applications involving characterization of ultrafast or rarely occurring phenomena. With the demonstrated spectral coverage of supercontinuum extending from near-infrared to over 10 μm in a single nonlinear fiber, there has been a clear push for the bandwidth rather than for attempting to optimize the dynamic properties of the generated spectrum. In this work we provide an experimental assessment of the shot-to-shot noise performance of supercontinuum generation in two types of soft glass photonic crystal fibers. Phase coherence and intensity fluctuations are compared for the cases of an anomalous dispersion-pumped fiber and an all-normal dispersion fiber. With the use of the dispersive Fourier transformation method, we demonstrate that a factor of 100 improvement in signal-to-noise ratio is achieved in the normal-dispersion over anomalous dispersion-pumped fiber for 390 fs long pump pulses. A double-clad design of the photonic lattice of the fiber is further postulated to enable a pump-related seeding mechanism of normal-dispersion supercontinuum broadening under sub-picosecond pumping, which is otherwise known for similar noise characteristics as modulation instability driven, soliton-based spectra. PMID:26759188

  4. The influence of drug loading on formulation structure and aerosol performance in carrier based dry powder inhalers.

    PubMed

    Young, Paul M; Wood, Owen; Ooi, Jesslynn; Traini, Daniela

    2011-09-15

    Previous studies have reported that carrier:drug ratio and carrier size influence the aerosol performance of dry powder inhalation systems. These previous studies were complicated by the heterogeneous nature of the carriers used, making it difficult to define an explicit relationship between parameters and performance. Here, the authors studied the influence of drug loading and carrier size on drug aerosol performance using homogeneous spherical model carriers. Different formulations containing drug (salbutamol sulphate) and carriers (polystyrene beads with median diameters of 82.8μm, 277.5μm and 582.9μm, respectively) were prepared by varying the ratio of carrier to drug (from ∼5:1 to ∼85:1). The surface morphology of the carrier particles and force of adhesion were investigated using atomic force microscopy, while the aerosol performance was evaluated using a multi-stage liquid impinger. The carrier surface morphology for all carrier sizes was homogenous with root-mean square roughness values ≤112nm. No significant difference in the force of adhesion between salbutamol sulphate and the three carrier sizes was observed. Significant differences in aerosol performance of salbutamol sulphate (measured as fine particle dose (FPD) and fraction (FPF)≤5μm) from the carriers were observed. Specifically, as carrier size increased FPF decreased. In comparison, as drug loading increased there was no change in FPF until a critical threshold was exceeded. Such observations suggest that: (A) aerosolisation performance is governed by carrier collisions and (B) when homogeneous carriers are used, the aerosol performance remains constant with respect to drug concentration, until the formulation transitions from an ordered mix to an agglomerated and/or segregated powder bed. PMID:21708238

  5. High-performance dispersive Raman and absorption spectroscopy as tools for drug identification

    NASA Astrophysics Data System (ADS)

    Pawluczyk, Olga; Andrey, Sam; Nogas, Paul; Roy, Andrew; Pawluczyk, Romuald

    2009-02-01

    Due to increasing availability of pharmaceuticals from many sources, a need is growing to quickly and efficiently analyze substances in terms of the consistency and accuracy of their chemical composition. Differences in chemical composition occur at very low concentrations, so that highly sensitive analytical methods become crucial. Recent progress in dispersive spectroscopy with the use of 2-dimensional detector arrays, permits for signal integration along a long (up to 12 mm long) entrance slit of a spectrometer, thereby increasing signal to noise ratio and improving the ability to detect small concentration changes. This is achieved with a non-scanning, non-destructive system. Two different methods using P&P Optica high performance spectrometers were used. High performance optical dispersion Raman and high performance optical absorption spectroscopy were employed to differentiate various acetaminophen-containing drugs, such as Tylenol and other generic brands, which differ in their ingredients. A 785 nm excitation wavelength was used in Raman measurements and strong Raman signals were observed in the spectral range 300-1800 cm-1. Measurements with the absorption spectrometer were performed in the wavelength range 620-1020 nm. Both Raman and absorption techniques used transmission light spectrometers with volume phase holographic gratings and provided sufficient spectral differences, often structural, allowing for drug differentiation.

  6. High-performance 3D printing of hydrogels by water-dispersible photoinitiator nanoparticles.

    PubMed

    Pawar, Amol A; Saada, Gabriel; Cooperstein, Ido; Larush, Liraz; Jackman, Joshua A; Tabaei, Seyed R; Cho, Nam-Joon; Magdassi, Shlomo

    2016-04-01

    In the absence of water-soluble photoinitiators with high absorbance in the ultraviolet (UV)-visible range, rapid three-dimensional (3D) printing of hydrogels for tissue engineering is challenging. A new approach enabling rapid 3D printing of hydrogels in aqueous solutions is presented on the basis of UV-curable inks containing nanoparticles of highly efficient but water-insoluble photoinitiators. The extinction coefficient of the new water-dispersible nanoparticles of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) is more than 300 times larger than the best and most used commercially available water-soluble photoinitiator. The TPO nanoparticles absorb significantly in the range from 385 to 420 nm, making them suitable for use in commercially available, low-cost, light-emitting diode-based 3D printers using digital light processing. The polymerization rate at this range is very fast and enables 3D printing that otherwise is impossible to perform without adding solvents. The TPO nanoparticles were prepared by rapid conversion of volatile microemulsions into water-dispersible powder, a process that can be used for a variety of photoinitiators. Such water-dispersible photoinitiator nanoparticles open many opportunities to enable rapid 3D printing of structures prepared in aqueous solutions while bringing environmental advantages by using low-energy curing systems and avoiding the need for solvents. PMID:27051877

  7. High-performance 3D printing of hydrogels by water-dispersible photoinitiator nanoparticles

    PubMed Central

    Pawar, Amol A.; Saada, Gabriel; Cooperstein, Ido; Larush, Liraz; Jackman, Joshua A.; Tabaei, Seyed R.; Cho, Nam-Joon; Magdassi, Shlomo

    2016-01-01

    In the absence of water-soluble photoinitiators with high absorbance in the ultraviolet (UV)–visible range, rapid three-dimensional (3D) printing of hydrogels for tissue engineering is challenging. A new approach enabling rapid 3D printing of hydrogels in aqueous solutions is presented on the basis of UV-curable inks containing nanoparticles of highly efficient but water-insoluble photoinitiators. The extinction coefficient of the new water-dispersible nanoparticles of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) is more than 300 times larger than the best and most used commercially available water-soluble photoinitiator. The TPO nanoparticles absorb significantly in the range from 385 to 420 nm, making them suitable for use in commercially available, low-cost, light-emitting diode–based 3D printers using digital light processing. The polymerization rate at this range is very fast and enables 3D printing that otherwise is impossible to perform without adding solvents. The TPO nanoparticles were prepared by rapid conversion of volatile microemulsions into water-dispersible powder, a process that can be used for a variety of photoinitiators. Such water-dispersible photoinitiator nanoparticles open many opportunities to enable rapid 3D printing of structures prepared in aqueous solutions while bringing environmental advantages by using low-energy curing systems and avoiding the need for solvents. PMID:27051877

  8. Investigating the Dissolution Performance of Amorphous Solid Dispersions Using Magnetic Resonance Imaging and Proton NMR.

    PubMed

    Tres, Francesco; Coombes, Steven R; Phillips, Andrew R; Hughes, Leslie P; Wren, Stephen A C; Aylott, Jonathan W; Burley, Jonathan C

    2015-01-01

    We have investigated the dissolution performance of amorphous solid dispersions of poorly water-soluble bicalutamide in a Kollidon VA64 polymeric matrix as a function of the drug loading (5% vs. 30% bicalutamide). A combined suite of state-of-the-art analytical techniques were employed to obtain a clear picture of the drug release, including an integrated magnetic resonance imaging UV-Vis flow cell system and 1H-NMR. Off-line 1H-NMR was used for the first time to simultaneously measure the dissolution profiles and rates of both the drug and the polymer from a solid dispersion. MRI and 1H-NMR data showed that the 5% drug loading compact erodes linearly, and that bicalutamide and Kollidon VA64 are released at approximately the same rate from the molecular dispersion. For the 30% extrudate, data indicated a slower water ingress into the compact which corresponds to a slower dissolution rate of both bicalutamide and Kollidon VA64. PMID:26378506

  9. The use of colloid probe microscopy to predict aerosolization performance in dry powder inhalers: AFM and in vitro correlation.

    PubMed

    Young, Paul M; Tobyn, Michael J; Price, Robert; Buttrum, Mark; Dey, Fiona

    2006-08-01

    The atomic force microscope (AFM) colloid probe technique was utilized to measure cohesion forces (separation energy) between three drug systems as a function of relative humidity (RH). The subsequent data was correlated with in vitro aerosolization data collected over the same RH range. Three drug-only systems were chosen for study; salbutamol sulphate (SS), triamcinolone acetonide (TAA), and di-sodium cromoglycate (DSCG). Analysis of the AFM and in vitro data suggested good correlations, with the separation energy being related inversely to the aerosolization performance (measured as fine particle fraction, FPF(LD)). In addition, the relationship between, cohesion, RH, and aerosolization performance was drug specific. For example, an increase in RH between 15% and 75% resulted in increased cohesion and decreased FPF(LD) for SS and DSCG. In comparison, for TAA, a decrease in cohesion and increased FPF(LD) was observed when RH was increased (15-75%). Linear regression analysis comparing AFM with in vitro data indicated R(2) values > 0.80, for all data sets, suggesting the AFM could be used to indicate in vitro aerosolization performance. PMID:16795018

  10. Scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and aerosol time-of-flight mass spectrometry (ATOFMS) single particle analysis of metallurgy plant emissions.

    PubMed

    Arndt, J; Deboudt, K; Anderson, A; Blondel, A; Eliet, S; Flament, P; Fourmentin, M; Healy, R M; Savary, V; Setyan, A; Wenger, J C

    2016-03-01

    The chemical composition of single particles deposited on industrial filters located in three different chimneys of an iron-manganese (Fe-Mn) alloy manufacturing plant have been compared using aerosol time-of-flight mass spectrometry (ATOFMS) and scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX). Very similar types of particles were observed using both analytical techniques. Calcium-containing particles dominated in the firing area of the sintering unit, Mn and/or Al-bearing particles were observed at the cooling area of the sintering unit, while Mn-containing particles were dominant at the smelting unit. SEM-EDX analysis of particles collected downstream of the industrial filters showed that the composition of the particles emitted from the chimneys is very similar to those collected on the filters. ATOFMS analysis of ore samples was also performed to identify particulate emissions that could be generated by wind erosion and manual activities. Specific particle types have been identified for each emission source (chimneys and ore piles) and can be used as tracers for source apportionment of ambient PM measured in the vicinity of the industrial site. PMID:26708757

  11. Mitigating dispersive spectrometer size-performance limitations with HTVS optical components

    NASA Astrophysics Data System (ADS)

    Meade, Jeffery T.; Behr, Bradford B.; Bismilla, Yusuf; Cenko, Andrew T.; DesRoches, Brandon; Henkin, Arie; Munro, Elizabeth A.; Slaa, Jared; Baker, Scott; Rempel, David; Hajian, Arsen R.

    2014-03-01

    Traditional spectrometer design requires trading off between resolution and throughput (two key parameters which define performance) and physical size. Increasing the internal beam diameter is the simplest method of improving the performance of an otherwise optimized spectrometer. Sadly, this increased beam size also directly translates into increased system volume, weight, and cost. Functional limitations on size (and thus performance) can also prevent spectroscopy from being used in applications where it would otherwise be a perfect fit. Tornado Spectral Systems' (TSS) High Throughput Virtual Slit (HTVS) redefines the performance-size limit by replacing the traditional slit in a spectrometer, allowing for designs that exceed traditional limitations on size and performance. Spectrometers can be made smaller while maintaining performance or system performance can be increased without increasing spectrometer size. Dispersive spectrometer theory is presented and used to construct a simulation that evaluated spectrometer performance based on volume for a slit-only and HTVS enabled instrument. Results show that as long as detector height is a non-limiting factor, HTVS enabled spectrometers have the potential to outperform slit-only spectrometers by factors up to several at equivalent volumes.

  12. Real time Raman imaging to understand dissolution performance of amorphous solid dispersions.

    PubMed

    Tres, Francesco; Treacher, Kevin; Booth, Jonathan; Hughes, Les P; Wren, Stephen A C; Aylott, Jonathan W; Burley, Jonathan C

    2014-08-28

    We have employed for the first time Raman spectroscopic imaging along with multi-variate curve resolution (MCR) analysis to investigate in real time and in-situ the dissolution mechanisms that underpin amorphous solid dispersions, with data being collected directly from the dosage form itself. We have also employed a novel rotating disk dissolution rate (RDDR) methodology to track, through the use of high-performance liquid chromatography (HPLC), the dissolution trends of both drug and polymer simultaneously in multi-component systems. Two formulations of poorly water-soluble felodipine in a polymeric matrix of copovidone VA64 which have different drug loadings of 5% and 50% w/w were used as models with the aim of studying the effects of increasing the amount of active ingredient on the dissolution performance. It was found that felodipine and copovidone in the 5% dispersion dissolve with the same dissolution rate and that no Raman spectral changes accompanied the dissolution, indicating that the two components dissolve as single entity, whose behaviour is dominated by water-soluble copovidone. For the 50% drug-loaded dispersion, partial RDDR values of both felodipine and copovidone were found to be extremely low. MCR Raman maps along with classical Raman/X-ray powder diffraction (XRPD) characterisation revealed that after an initial loss of copovidone from the extrudate the drug re-crystallises, pointing to a release dynamics dependent on the low water solubility and high hydrophobicity of felodipine. Raman imaging revealed different rates of transition from amorphous to crystalline felodipine at different locations within the dosage form. PMID:24910191

  13. Dispersion optimization of nonlinear glass photonic crystal fibers and impact of fabrication tolerances on their telecom nonlinear applications performance

    NASA Astrophysics Data System (ADS)

    Kanka, Jiri

    2009-05-01

    For most telecom nonlinear applications a high effective nonlinearity, low group velocity dispersion with a low dispersion slope and a short fibre length are the key parameters. Combining photonic crystal fibre (PCF) technology with highly nonlinear glasses could meet these requirements very well. We have performed dispersion optimization of PCFs made from selected nonlinear glasses with a solid core and small number of hexagonally arrayed air holes. The optimization procedure employs the Nelder-Mead downhill simplex algorithm. For the modal analysis of the photonic crystal fibre structure a fully-vectorial mode solver based on the finite element method is used. We have obtained two types of dispersion optimized nonlinear PCF designs: PCFs of the first type are single-mode and highly nonlinear with a small and flattened dispersion in the 1500-1600 nm range. These PCF structures have air holes hexagonally arrayed in from 3 to 5 rings, however, their dispersion characteristics are very sensitive to variations in structural parameters. PCFs of the second type are two-ring PCFs with larger multi-mode cores. They have fundamental mode's zero dispersion wavelength around 1550 nm with non-zero moderate dispersion slopes which are less sensitive to structural variation. It is supposed that this alternative PCF design will be easier to fabricate. The effects of fabrication imprecision on the dispersion characteristics for both PCF designs are demonstrated numerically and discussed in the context of nonlinear telecom applications.

  14. Processing solubility enhancement and Nanoparticles dispersion enhanced Performance Materials through thermomagnetic processing

    SciTech Connect

    Ludtka, Gerard Michael; Ludtka, Gail Mackiewicz-; Rios, Orlando; Kisner, Roger A; Muralidharan, Govindarajan; Manuel, Michele Viola; Manuel, Michele

    2012-01-01

    This research demonstrates that significantly enhanced materials microstructures and improved performance can be achieved by coupling two previously independent materials research concepts, namely, the thermo-magnetic processing (T-MP)1 and the electromagnetic acoustic transducer (EMAT)2 technologies. In prior, separate NHMFL research endeavors, ORNL researchers have demonstrated that: (1) thermo-magnetic processing (T-MP) can significantly enhance Ni solubility in Fe by up to 30%; and (2) using the electromagnetic acoustic transducer (EMAT) technology can significantly improve cast product homogeneity. Based on these earlier successful results, we proposed simultaneously coupling these two R&D approaches/eff ects (i.e., T-MP with EMAT), in order to simultaneously achieve: (1) enhanced elemental solid-solubility in Mg and in at least one Fe-based alloy; and (2) uniform dispersion of intentional additions of inert nanoparticles in Mg. Developing homogeneous dispersions of inert nanoparticles is and has been pursued as one of the holy grails for achieving unprecedented materials performance and highly desired mechanical properties, e.g., in creep and oxidation resistant alloys. Successfully coupling these two technologies would provide the ability to create uniquely controlled nano-scale microstructures that currently are unachievable by any other materials processing technologies.

  15. Design considerations and performance characteristics of AirSentinel: a new UV-LIF bio-aerosol threat detection trigger

    NASA Astrophysics Data System (ADS)

    DeFreez, Richard; Merrill, Ezra; Albanna, Sam; Davis, Bert; Call, Charles

    2005-10-01

    AirSentinel® is a new low cost, compact ultraviolet-based light induced fluorescence (UV-LIF) bio-aerosol threat detection trigger. Earlier UV-LIF triggers, for example, FLAPS, BARTS, BAWS, Bioni, and BioLert, have used UV laser sources to induce fluorescence of biological aerosols. Two recent developments from the DARPA MTO SUVOS program, BAST and TAC-BIO, use UV LEDs for the same purpose, thereby broadening the term UV-LIF to mean laser or LED induced autofluorescence. All of these earlier triggers interrogate aerosols on a particle-by-particle basis on- the-fly. The major trade-off for these instruments is cost, size, and complexity versus counting efficiency (probability of detection) with the lower size end of the respirable range being most difficult to detect. AirSentinel® employs a different approach to UV-LIF detection: aerosol concentration by collection on a surface, surface interrogation, and surface rejuvenation prior to repeated concentration and interrogation cycles. Aerosol particle concentration via impaction on a surface addresses the issue of small particle counting efficiency since the fluorescence from the sum of the particles is the sum of the fluorescence signals from the collected particles, typically hundreds or thousands in number. Surface interrogation for a LIF signal is accomplished by illumination with a 280 nm and/or a 365 nm LED. As expected, test results show better relative detection performance using 280 nm excitation LEDs for bio-toxin simulants and somewhat better performance at 365 nm for standard Bacillus globigii spore targets. AirSentinel® beta technology is currently in long term testing in a number of public and other government buildings.

  16. ON THE IMPACT OF THE HUMAN (CHILD) MICROCLIMATE ON PASSIVE AEROSOL MONITOR PERFORMANCE

    EPA Science Inventory

    Research into the wind microclimate and its effect on the accuracy and effectiveness of passive aerosol monitors is expanding as the importance of personal monitoring versus regional monitoring increases. The important phenomena for investigation include thermal and dynamic eff...

  17. Performance of the chemical mass balance model with simulated local-scale aerosols

    NASA Astrophysics Data System (ADS)

    Javitz, H. S.; Watson, J. G.; Robinson, N.

    A general methodology for performing simulations of the Chemical Mass Balance (CMB) model is developed and applied to simple and complex local scale scenarios. The simple scenario consists of crustal, coal-fired power plant, motor vehicle and vegetative burning sources; the complex scenario adds oil-fired power plant, ocean, steel mill, lead smelter, municipal incinerator and background aerosol sources. Daily receptor filter concentrations of the most commonly measured elements in the primary emissions are simulated. These simulations incorporate daily fluctuations in source strengths, daily fluctuations in source profiles (as parameterized by a coefficient of variation, or CV, of temporal source profiles) and measurement error at the receptor (as parameterized by a CV of measurement error). The CMB is applied to each daily measurement using a source library containing all sources and their long-term profiles (which, though correct on average, are incorrect on any particular day). The extent of agreement of the actual and CMBestimated primary emission source strengths is measured as an average absolute error (AAE, the absolute difference between the daily actual and estimated primary emission source strengths averaged over 100 simulated days). These moderately realistic simulations provide an encouraging picture of CMB accuracy and precision. The CMB yields acceptable accuracy and precision (an AAE of 50% or less) even when the CV of temporal source profiles is 25% and the CV of measurement error is 10%.

  18. Minimal amounts of dipalmitoylphosphatidylcholine improve aerosol performance of spray-dried temocillin powders for inhalation.

    PubMed

    Cuvelier, Brieuc; Eloy, Pierre; Loira-Pastoriza, Cristina; Ucakar, Bernard; Sanogo, Abdoul Aziz; Dupont-Gillain, Christine; Vanbever, Rita

    2015-11-30

    Administration of antibiotics by inhalation can greatly improve drug targeting to the site of respiratory infections. In addition, dry powder inhalers are particularly convenient for the patients. The purposes of this study were to demonstrate the interest of pulmonary temocillin delivery to reach high temocillin concentrations locally in the lungs as well as to prepare a spray-dried temocillin powder for inhalation using a minimal amount of generally recognized as safe excipients. Intratracheal instillation of a temocillin solution allowed to reach higher and more sustained drug concentrations in the lungs than intravenous injection in mice, although a 10-fold lower temocillin dose was delivered intratracheally than systemically. A spray-dried powder of pure temocillin presented a fine particle fraction of 9% of the dose loaded in the inhaler. However, the incorporation of 0.5% to 20% of dipalmitoylphosphatidylcholine (DPPC) in the powder increased the fine particle fraction 4- to 5-fold. X-ray photoelectron spectroscopy and X-ray diffraction revealed that DPPC concentrated at the particle surface with its aliphatic chains laterally packed. The minimal amount of DPPC needed to improve the aerosol performance of temocillin supports the use of this excipient in the formulation of cohesive antibiotic powders for inhalation. PMID:26456267

  19. Performance of a FieldSpec spectroradiometer for aerosol optical depth retrieval: method and preliminary results.

    PubMed

    Bassani, Cristiana; Estellés, Víctor; Campanelli, Monica; Cavalli, Rosa Maria; Martínez-Lozano, José Antonio

    2009-04-10

    The performance of a FieldSpec spectroradiometer for retrieving aerosol optical depth (AOD) has been assessed after modifying its basic configuration in order to measure direct solar irradiance at ground level. The FieldSpec measurements were obtained during four summertime days in the years 2004 and 2005, over a Spanish agricultural site in Barrax, Albacete (30 degrees 3(') N, 2 degrees 6(') W, 700 m a.s.l.), in the framework of two European Space Agency mission remote sensing field campaigns. From the whole FieldSpec spectral domain (350-2500 nm) the AOD was extracted for channels within atmospheric windows. The instrument was calibrated by means of the standard Langley plot method, performed at a high mountain site in Italy. The AOD retrieved by the FieldSpec has been validated by comparison with the AOD obtained from a colocated CIMEL CE318 Sun photometer. The FieldSpec AOD spectra were convoluted with the CE318 filter transmission functions in order to make both datasets comparable. Our results show that both datasets are very similar (R(2) around 0.9) for all the channels from the CE318, with an average deviation of about 0.02. The temporal evolution of the AOD was accurately monitored by the FieldSpec under different atmospheric conditions, as was the case for a previously reported mineral dust intrusion. As a conclusion, the comparison performed in this study shows that the FieldSpec spectroradiometer is a suitable instrument for retrieving the AOD in different atmospheric situations. PMID:19363533

  20. Design and performance of an automatic regenerating adsorption aerosol dryer for continuous operation at monitoring sites

    NASA Astrophysics Data System (ADS)

    Tuch, T. M.; Haudek, A.; Müller, T.; Nowak, A.; Wex, H.; Wiedensohler, A.

    2009-04-01

    Sizes of aerosol particles depend on the relative humidity of their carrier gas. Most monitoring networks require therefore that the aerosol is dried to a relative humidity below 50% RH to ensure comparability of measurements at different sites. Commercially available aerosol dryers are often not suitable for this purpose at remote monitoring sites. Adsorption dryers need to be regenerated frequently and maintenance-free single column Nafion dryers are not designed for high aerosol flow rates. We therefore developed an automatic regenerating adsorption aerosol dryer with a design flow rate of 1 m3/h. Particle transmission efficiency of this dryer has been determined during a 3 weeks experiment. The lower 50% cut-off was found to be below 3 nm at the design flow rate of the instrument. Measured transmission efficiencies are in good agreement with theoretical calculations. One drier has been successfully deployed in the Amazonas river basin. From this monitoring site, we present data from the first 6 months of measurements (February 2008-August 2008). Apart from one unscheduled service, this dryer did not require any maintenance during this time period. The average relative humidity of the dried aerosol was 27.1+/-7.5% RH compared to an average ambient relative humidity of nearly 80% and temperatures around 30°C. This initial deployment demonstrated that these dryers are well suitable for continuous operation at remote monitoring sites under adverse ambient conditions.

  1. Improved performance of U-Mo dispersion fuel by Si addition in Al matrix.

    SciTech Connect

    Kim, Y S; Hofman, G L

    2011-06-01

    The purpose of this report is to collect in one publication and fit together work fragments presented in many conferences in the multi-year time span starting 2002 to the present dealing with the problem of large pore formation in U-Mo/Al dispersion fuel plates first observed in 2002. Hence, this report summarizes the excerpts from papers and reports on how we interpreted the relevant results from out-of-pile and in-pile tests and how this problem was dealt with. This report also provides a refined view to explain in detail and in a quantitative manner the underlying mechanism of the role of silicon in improving the irradiation performance of U-Mo/Al.

  2. Energy Dispersive X-Ray and Electrochemical Impedance Spectroscopies for Performance and Corrosion Analysis of PEMWEs

    NASA Astrophysics Data System (ADS)

    Steen, S. M., Iii; Zhang, F.-Y.

    2014-11-01

    Proton exchange membrane water electrolyzers (PEMWEs) are a promising energy storage technology due to their high efficiency, compact design, and ability to be used in a renewable energy system. Before they are able to make a large commercial impact, there are several hurdles facing the technology today. Two powerful techniques for both in-situ and ex- situ characterizations to improve upon their performance and better understand their corrosion are electrochemical impedance spectroscopy and energy dispersive x-ray spectroscopy, respectively. In this paper, the authors use both methods in order to characterize the anode gas diffusion layer (GDL) in a PEMWE cell and better understand the corrosion that occurs in the oxygen electrode during electrolysis.

  3. Compact and High Performance Spectrometers based on Novel Transmission Gratings with High Dispersion.

    PubMed

    Rasmussen, Thomas Peter

    2016-05-01

    In this article we outline how ultra-compact, yet high performance spectrometers can be designed and built with highly dispersive transmission gratings. By using fused silica as the grating material, and by careful design of the detailed grating structure, we demonstrate an ultraviolet spectrometer with a high and nearly flat efficiency from 178 to 409 nm, a resolution of 0.2 nm, and dimensions of only 61 mm × 64 mm × 19 mm. We tested this spectrometer in a laser-induced breakdown spectroscopy experiment and showed that the spectral information gathered with the spectrometer can be used to obtain quantitative results for sulfur. PMID:27002126

  4. Wireless Performance of a Fully Passive Neurorecording Microsystem Embedded in Dispersive Human Head Phantom

    NASA Technical Reports Server (NTRS)

    Schwerdt, Helen N.; Chae, Junseok; Miranda, Felix A.

    2012-01-01

    This paper reports the wireless performance of a biocompatible fully passive microsystem implanted in phantom media simulating the dispersive dielectric properties of the human head, for potential application in recording cortical neuropotentials. Fully passive wireless operation is achieved by means of backscattering electromagnetic (EM) waves carrying 3rd order harmonic mixing products (2f(sub 0) plus or minus f(sub m)=4.4-4.9 GHZ) containing targeted neuropotential signals (fm approximately equal to 1-1000 Hz). The microsystem is enclosed in 4 micrometer thick parylene-C for biocompatibility and has a footprint of 4 millimeters x 12 millimeters x 500 micrometers. Preliminary testing of the microsystem implanted in the lossy biological simulating media results in signal-to-noise ratio's (SNR) near 22 (SNR approximately equal to 38 in free space) for millivolt level neuropotentials, demonstrating the potential for fully passive wireless microsystems in implantable medical applications.

  5. Dispersion and treatment performance analysis of an UASB reactor under different hydraulic loading rates.

    PubMed

    Peña, M R; Mara, D D; Avella, G P

    2006-02-01

    Mixing and transport phenomena affect the efficiency of all bioreactor configurations. An even mixing pattern at the macro-level is desirable to provide good conditions for substrate transport to, and from, the microbial aggregates. The state of segregation of particulate material in the reactor is also important. The production of biogas in anaerobic reactors is another factor that affects mixing intensity and hence the interactions between the liquid, solid and gaseous phases. The CSTR model with some degree of short-circuiting, dead zones and bypassing flows seems to describe the overall hydrodynamics of UASBs. However, few data are available in the literature for full-scale reactors that relate process performance to mixing characteristics. Dispersion studies using LiCl were done for four hydraulic loading rates on a full-scale UASB treating domestic wastewater in Ginebra, Valle del Cauca, southwest Colombia. COD, TSS, and Settleable Solids were used to evaluate the performance of organic matter removal. The UASB showed a complete mixing pattern for hydraulic loading rates close to the design value (i.e. Q = 10-13l s(-1) and HRT=8-6 h). Gross mixing distortions and localised stagnant zones, short-circuiting and bypass flows were found in the sludge bed and blanket zones for both extreme conditions (underloading and overloading). The liquid volume contained below the gas-liquid-solid separator was found to contribute to the overall stagnant volume, particularly when the reactor was underloaded. The removal of organic matter showed a log-linear correlation with the dispersion number. PMID:16405944

  6. Understanding the Different Effects of Inhaler Design on the Aerosol Performance of Drug-Only and Carrier-Based DPI Formulations. Part 1: Grid Structure.

    PubMed

    Leung, Cassandra Ming Shan; Tong, Zhenbo; Zhou, Qi Tony; Chan, John Gar Yan; Tang, Patricia; Sun, Siping; Yang, Runyu; Chan, Hak-Kim

    2016-09-01

    The design of a dry powder inhaler device has significant influence on aerosol performance; however, such influence may be different between the drug-only and carrier-based formulations. The present study aims to examine the potential difference on the dispersion between these distinct types of formulations, using Aerolizer(®) as a model inhaler with the original or modified (cross-grid) designs. A coupled CFD-discrete element method analysis was employed to determine the flow characteristics and particle impaction. Micronized salbutamol sulphate as a drug-only formulation and three lactose carrier-based formulations with various drug-to-carrier weight ratios 1:5, 1:10 and 1:100 were used. The in vitro aerosolization performance was assessed by a next-generation impactor operating at 100 L/min. Using the original device, FPFloaded was reduced from 47.5 ± 3.8% for the drug-only formulation to 31.8 ± 0.7%, 32.1 ± 0.7% and 12.9 ± 1.0% for the 1:5, 1:10 and 1:100 formulations, respectively. With the cross-grid design, powder-mouthpiece impaction was increased, which caused not only powder deagglomeration but also significant drug retention (doubling or more) in the mouthpiece, and the net result is a significant decrease in FPFloaded to 36.8 ± 1.2%, 20.9 ± 2.6% and 21.9 ± 1.5% for the drug-only, 1:5 and 1:10 formulations, respectively. In contrast, the FPFloaded of the 1:100 formulation remained the same at 12.1 ± 1.3%, indicating the increased mouthpiece drug retention was compensated by increased drug detachment from carriers caused by increased powder-mouthpiece impaction. In conclusion, this study has elucidated different effects and the mechanism on the aerosolization of varied dry powder inhaler formulations due to the grid design. PMID:27161214

  7. A High Performance Liquid Chromatography Method for Determination of Levoglucosan Concentrations in Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Dixon, R. W.; Baltzell, G.

    2002-12-01

    Levoglucosan (1,6-anhydro-β-D-glucopyranose) recently has been measured in atmospheric aerosols where it is a major organic compound originating from biomass combustion. Past analysis methods have used gas chromatography with and without derivitization. We have developed a method for analyzing levoglucosan in atmospheric aerosols using high peformance liquid chromatography (HPLC) with a new detection method called aerosol charge detection. In aerosol charge detection, the column effluent is converted to an aerosol that is charged by passage near a corona discharge region and detected by charge collection. A column specific for carbohydrate compounds, which separates compounds by ligand-exchange and by partitioning based on polarity, was used for the separation using a 100% water eluent at 60°C. Under these conditions, aerosol filter samples extracted in methanol and water gave peaks with the same retention time as a levoglucosan standard. The detection limit was estimated to be about 0.1 μg mL-1 for extracts or 5 to 10 ng m-3 for air sample volumes employed. Samples collected at locations in central New Mexico and central California were found to contain concentrations of levoglucosan from the detection limit to 270 ng m-3, with higher concentrations observed under colder conditions when more fireplaces would tend to be in use. Mannosan (1,6-anhydro-β-D-mannopyranose), another monosaccharide anhydride, also was observed in one sample. The presence of other organic compounds, which have not yet been identified, was inferred by other observed peaks and by an increased baseline in sample chromatograms.

  8. Performance of High Flow Rate Personal Respirable Samplers When Challenged with Mineral Aerosols of Different Particle Size Distributions.

    PubMed

    Stacey, Peter; Thorpe, Andrew; Echt, Alan

    2016-05-01

    It is thought that the performance of respirable samplers may vary when exposed to dust aerosols with different particle sizes and wind speeds. This study investigated the performance of the GK 4.16 (RASCAL), GK 2.69, PPI 8, and FSP 10, high flow rate personal samplers when exposed to aerosols of mineral dust in a wind tunnel at two different wind speeds (1 and 2 m s(-1)) and orientations (towards and side-on to the source of emission). The mass median aerodynamic diameter of four aerosolized test dusts ranged from 8 to 25 µm with geometric standard deviations from 1.6 to 2 µm. The performance of each sampler type was compared with that of the SIMPEDS (Higgins-Dewell design) sampler. There was slight evidence to suggest that the performance of the FSP 10 is affected by the direction of the inlet relative to the air flow, although this was not significant when most respirable dust concentrations were compared, possibly due to the variability of paired dust concentration results. The GK 2.69, RASCAL, and PPI 8 samplers had similar performances, although the results when side-on to the emission source were generally slightly lower than the SIMPEDS. Despite slight differences between respirable dust concentrations the respirable crystalline silica values were not significantly different from the SIMPEDS. The GK family of cyclones obtained most precise results and more closely matched the SIMPEDS. A comparison with dust concentration results from previous calm air chamber studies (where wind speeds were < 0.4 m s(-1)) found that the relative performance between samplers was similar to those observed in this work indicating consistent performance relative to the SIMPEDS in both calm and moving air. PMID:26865560

  9. Performance of High Flow Rate Personal Respirable Samplers When Challenged with Mineral Aerosols of Different Particle Size Distributions

    PubMed Central

    Stacey, Peter; Thorpe, Andrew; Echt, Alan

    2016-01-01

    It is thought that the performance of respirable samplers may vary when exposed to dust aerosols with different particle sizes and wind speeds. This study investigated the performance of the GK 4.16 (RASCAL), GK 2.69, PPI 8, and FSP 10, high flow rate personal samplers when exposed to aerosols of mineral dust in a wind tunnel at two different wind speeds (1 and 2 m s−1) and orientations (towards and side-on to the source of emission). The mass median aerodynamic diameter of four aerosolized test dusts ranged from 8 to 25 µm with geometric standard deviations from 1.6 to 2 µm. The performance of each sampler type was compared with that of the SIMPEDS (Higgins–Dewell design) sampler. There was slight evidence to suggest that the performance of the FSP 10 is affected by the direction of the inlet relative to the air flow, although this was not significant when most respirable dust concentrations were compared, possibly due to the variability of paired dust concentration results. The GK 2.69, RASCAL, and PPI 8 samplers had similar performances, although the results when side-on to the emission source were generally slightly lower than the SIMPEDS. Despite slight differences between respirable dust concentrations the respirable crystalline silica values were not significantly different from the SIMPEDS. The GK family of cyclones obtained most precise results and more closely matched the SIMPEDS. A comparison with dust concentration results from previous calm air chamber studies (where wind speeds were < 0.4 m s−1) found that the relative performance between samplers was similar to those observed in this work indicating consistent performance relative to the SIMPEDS in both calm and moving air. PMID:26865560

  10. Synthesis, Characterization, and Catalytic Performance of Highly Dispersed Vandium Grafted SBA-15 Catalyst

    SciTech Connect

    Du,G.; Lim, S.; Pinault, M.; Wang, C.; Fang, F.; Pfefferle, L.; Hall, G.

    2008-01-01

    Vanadium oxide grafted on mesoporous silica SBA-15 has been synthesized using a controlled grafting process. Its structure has been thoroughly investigated using different characterization techniques, including N2-physisorption, X-ray diffraction, transmission electron microscopy (TEM), Raman spectroscopy, H2 temperature-programmed reduction, X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS). The spectroscopic results revealed that under dehydrated conditions, the grafted vanadium domains are highly dispersed on the SBA-15 surface, composed predominately of isolated VO4 units with distorted tetrahedral coordination. The suggested ({triple_bond}SiO)3V{double_bond}O sites on the silica surface include one short bond ({approx}1.54 Angstroms) and three long bonds (1.74 Angstroms). Methanol oxidation was used as a chemical probe reaction to examine the catalytic properties of these catalysts. At low vanadium loading, the vanadium species grafted on the surface show structural properties similar to those of vanadium-incorporated MCM-41 catalyst. However, the present mesoporous V-SBA-15 catalysts in the oxidation of methanol to formaldehyde show remarkable catalytic performance compared with that of VOx/SBA-15 catalysts synthesized through a conventional wet impregnation method, which has been attributed to the homogeneous dispersion and uniformity of the catalytic vanadium species achieved on the SBA-15 support with large pore diameter and surface area. The acidic properties of V-SBA-15 was investigated by pyridine temperature-programmed desorption, which indicated the existence of both Lewis and Broensted acid sites of the surface.

  11. Performance of Steady-State Dispersion Models Under Low Wind-Speed Conditions

    NASA Astrophysics Data System (ADS)

    Qian, Wenjun; Venkatram, Akula

    2011-03-01

    We examine the performance of two steady-state models, a numerical solution of the advection-diffusion equation and the Gaussian plume-model-based AERMOD (the American Meteorological Society/Environmental Protection Agency Regulatory Model), to predict dispersion for surface releases under low wind-speed conditions. A comparison of model estimates with observations from two tracer studies, the Prairie Grass experiment and the Idaho Falls experiment indicates that about 50% of the concentration estimates are within a factor of two of the observations, but the scatter is large: the 95% confidence interval of the ratio of the observed to estimated concentrations is about 4. The model based on the numerical solution of the diffusion equation in combination with the model of Eckman (1994, Atmos Environ 28:265-272) for horizontal spread performs better than AERMOD in explaining the observations. Accounting for meandering of the wind reduces some of the overestimation of concentrations at low wind speeds. The results deteriorate when routine one-level observations are used to construct model inputs. An empirical modification to the similarity estimate of the surface friction velocity reduces the underestimation at low wind speeds.

  12. Experimental methods to determine inhalability and personal sampler performance for aerosols in ultra-low windspeed environments.

    PubMed

    Schmees, Darrah K; Wu, Yi-Hsuan; Vincent, James H

    2008-12-01

    Most previous experiments of aerosol inhalability as it relates to particle aerodynamic diameter were conducted in wind tunnels for windspeeds greater than 0.5 m s(-1). While that body of work was used to establish an inhalable aerosol convention, results from studies in calm air chambers (for essentially zero windspeed) are being discussed as the basis of a modified criterion. Meanwhile, however, information is lacking for windspeeds in the intermediate range, which--it so happens--pertain to most actual workplaces. With this in mind, we have developed a new experimental system to assess inhalability and personal sampler performance for aerosols with particle aerodynamic diameter within the range from 6 to 90 microm for ultra-low windspeed environments from about 0.1 to 0.5 m s(-1). In this range of conditions for particle size and windspeed, controlled aerosol experiments are very difficult to perform, most notably with respect to the problem of achieving uniform spatial distributions of both test aerosols and air velocity. In the work reported in this paper, we have addressed these difficulties in a new, custom-designed experimental facility. It is a novel wind tunnel design that provides stable and controllable low-turbulence air movement, and allows for the delivery of test aerosol to the working section both from upstream (as in conventional wind tunnel experiments) and from above (as in calm air studies). In this system, losses by elutriation of particles that are being convected in the horizontal aerosol flow are compensated by particles entering from above by gravitational settling. An important feature of the new facility is the life-size, breathing mannequin that contains physical means to achieve any combination of mouth and nasal inspiration and expiration, and allows any desired relevant breathing flowrate and pattern by means of an external computer-controlled breathing simulator. Special steps were taken in the detailed design to ensure that

  13. FUNDAMENTAL PERFORMANCE OF A DISPERSED FIXED DELAY INTERFEROMETER IN SEARCHING FOR PLANETS AROUND M DWARFS

    SciTech Connect

    Wang Ji; Ge Jian; Jiang Peng; Zhao Bo

    2011-09-10

    We present a new method to calculate fundamental Doppler measurement limits with a dispersed fixed delay interferometer (DFDI) in the near-infrared (NIR) wavelength region for searching for exoplanets around M dwarfs in the coming decade. It is based on calculating the Q factor, a measure of flux-normalized Doppler sensitivity in the fringing spectra created with DFDI. We calculate the Q factor as a function of spectral resolution R, stellar-projected rotational velocity Vsin i, stellar effective temperature T{sub eff}, and optical path difference (OPD) of the interferometer. We also compare the DFDI Q factor to that for the popular cross-dispersed echelle spectrograph method (the direct echelle (DE) method). We find that (1) Q{sub DFDI} is a factor of 1.5-3 higher than Q{sub DE} at R ranging from 5000 to 20,000; (2) Q{sub DFDI} and Q{sub DE} converge at a very high R (R {>=} 100,000); (3) Q{sub DFDI} increases as R increases and Vsin i deceases; (4) for a given R, Q{sub DFDI} increases as T{sub eff} drops from 3100 K to 2400 K (M4V to M9V). We also investigate how Q{sub DFDI} is affected by OPD and find that a 5 mm deviation from the optimal OPD does not significantly affect Q{sub DFDI} (10% or less) for a wide range of R. Given that the NIR Doppler measurement is likely to be detector-limited for a while, we introduce new merit functions, which is directly related to photon-limited radial velocity (RV) uncertainty, to evaluate Doppler performance with the DFDI and DE methods. We find that DFDI has strength in wavelength coverage and multi-object capability over the DE for a limited detector resource. We simulate the performance of the InfraRed Exoplanet Tracker (IRET) based on the DFDI design, being considered for the next generation IR Doppler measurements. The predicted photon-limited RV uncertainty suggests that IRET is capable of detecting Earth-like exoplanets in habitable zone around nearby bright M dwarfs if they exist. A new method is developed to

  14. Real-scale miscible grout injection experiment and performance of advection-dispersion-filtration model

    NASA Astrophysics Data System (ADS)

    Bouchelaghem, F.; Vulliet, L.; Leroy, D.; Laloui, L.; Descoeudres, F.

    2001-10-01

    A model was developed, to describe miscible grout propagation in a saturated deformable porous medium, based on Bear's statistical model with spatial volume averaging. In a previous paper, the model was first successfully confronted to one-dimensional laboratory experiments.In the present paper, the numerical model is used to simulate practical grouting operation in a cylindrical injection model. The cylindrical injection model lends itself to study main flow and propagation character istics for a dispersed suspension-type grout, under axisymmetric conditions close to real scale conditions.Comparison between numerical solutions and experimental results is essential to confirm the validity and accuracy of the proposed model from a phenomenological standpoint. The numerical model performances show that the underlying mathematical model constitutes a realistic predictive model reproducing most prominent features during injection of a suspension-type grout into a deformable porous medium. The basic mechanism by which injected miscible grout permeates a soil mass is discussed in detail. Such a tool leads to quality control criteria for grouting on a theoretical basis, which complements existing criteria acquired through engineering practice.

  15. Magnetic fluid with high dispersion and heating performance using nano-sized Fe3O4 platelets

    NASA Astrophysics Data System (ADS)

    Kishimoto, Mikio; Miyamoto, Ryoichi; Oda, Tatsuya; Yanagihara, Hideto; Ohkohchi, Nobuhiro; Kita, Eiji

    2016-01-01

    Magnetic fluid with high dispersion and heating performance was developed using 30 to 50 nm platelet Fe3O4 particles. This fluid was prepared by mechanical dispersion in ethyl alcohol with a silane coupling agent, bonding with polyethylene glycol (PEG), and removal of aggregates formed by precipitation. The peak diameter of the resulting Fe3O4 particles, measured by dynamic light scattering, was approximately 150 nm. The fluid exhibited a 300 W/g specific loss power (measured at 114 kHz by a 50.9 kA/m magnetic field). Distribution of the Fe3O4 particles in tissues was observed by intravenously administrating the fluid in mice. The Fe3O4 particles passed through the lungs, and were uniformly distributed throughout the liver and spleen. High dispersion and high heating performance were simultaneously achieved in the magnetic fluid using platelet Fe3O4 particles surface modified with PEG.

  16. Simulating industrial emissions using atmospheric dispersion modeling system: model performance and source emission factors.

    PubMed

    El-Fadel, M; Abi-Esber, L

    2012-03-01

    In this paper, the Gaussian Atmospheric Dispersion Modeling System (ADMS4) was coupled with field observations of surface meteorology and concentrations of several air quality indicators (nitrogen oxides (NOx), carbon monoxide (CO), fine particulate matter (PM10) and sulfur dioxide (SO2)) to test the applicability of source emission factors set by the European Environment Agency (EEA) and the United States Environmental Protection Agency (USEPA) at an industrial complex. Best emission factors and data groupings based on receptor location, type of terrain and wind speed, were relied upon to examine model performance using statistical analyses of simulated and observed data. The model performance was deemed satisfactory for several scenarios when receptors were located at downwind sites with index of agreement 'd' values reaching 0.58, fractional bias 'FB' and geometric mean bias 'MG' values approaching 0 and 1, respectively, and normalized mean square error 'NMSE' values as low as 2.17. However, median ratios of predicted to observed concentrations 'Cp/Co' at variable downstream distances were 0.01, 0.36, 0.76 and 0.19 for NOx, CO, PM10 and SO2, respectively, and the fraction of predictions within a factor of two of observations 'FAC2' values were lower than 0.5, indicating that the model could not adequately replicate all observed variations in emittant concentrations. Also, the model was found to be significantly sensitive to the input emission factor bringing into light the deficiency in regulatory compliance modeling which often uses internationally reported emission factors without testing their applicability. PMID:22482291

  17. Preliminary aerosol generator design studies

    NASA Technical Reports Server (NTRS)

    Stampfer, J. F., Jr.

    1976-01-01

    The design and construction of a prototype vaporization generator for highly dispersed sodium chloride aerosols is described. The aerosol generating system is to be used in the Science Simulator of the Cloud Physics Laboratory Project and as part of the Cloud Physics Laboratory payload to be flown on the shuttle/spacelab.

  18. Design, Qualification, and On Orbit Performance of the CALIPSO Aerosol Lidar Transmitter

    NASA Technical Reports Server (NTRS)

    Hovis, Floyd E.; Witt, Greg; Sullivan, Edward T.; Le, Khoa; Weimer, Carl; Applegate, Jeff; Luck, William S., Jr.; Verhapen, Ron; Cisewski, Michael S.

    2007-01-01

    The laser transmitter for the CALIPSO aerosol lidar mission has been operating on orbit as planned since June 2006. This document discusses the optical and laser system design and qualification process that led to this success. Space-qualifiable laser design guidelines included the use of mature laser technologies, the use of alignment sensitive resonator designs, the development and practice of stringent contamination control procedures, the operation of all optical components at appropriately derated levels, and the proper budgeting for the space-qualification of the electronics and software.

  19. Design, characterization, and aerosolization of organic solution advanced spray-dried moxifloxacin and ofloxacin dipalmitoylphosphatidylcholine (DPPC) microparticulate/nanoparticulate powders for pulmonary inhalation aerosol delivery

    PubMed Central

    Duan, Jinghua; Vogt, Frederick G; Li, Xiaojian; Hayes, Don; Mansour, Heidi M

    2013-01-01

    The aim of this study was to design and develop respirable antibiotics moxifloxacin (MOXI) hydrochloride and ofloxacin (OFLX) microparticles and nanoparticles, and multifunctional antibiotics particles with or without lung surfactant 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) for targeted dry powder inhalation delivery as a pulmonary nanomedicine. Particles were rationally designed and produced by advanced spray-drying particle engineering from an organic solution in closed mode (no water) from dilute solution. Scanning electron microscopy indicated that these particles had both optimal particle morphology and surface morphology, and the particle size distributions were suitable for pulmonary delivery. Comprehensive and systematic physicochemical characterization and in vitro aerosol dispersion performance revealed significant differences between these two fluoroquinolone antibiotics following spray drying as drug aerosols and as cospray-dried antibiotic drug: DPPC aerosols. Fourier transform infrared spectroscopy and confocal Raman microspectroscopy were employed to probe composition and interactions in the solid state. Spray-dried MOXI was rendered noncrystalline (amorphous) following organic solution advanced spray drying. This was in contrast to spray-dried OFLX, which retained partial crystallinity, as did OFLX:DPPC powders at certain compositions. Aerosol dispersion performance was conducted using inertial impaction with a dry powder inhaler device approved for human use. The present study demonstrates that the use of DPPC offers improved aerosol delivery of MOXI as cospray-dried microparticulate/nanoparticulate powders, whereas residual partial crystallinity influenced aerosol dispersion of OFLX and most of the compositions of OFLX:DPPC inhalation powders. PMID:24092972

  20. Performance of a dispersion model to estimate methane loss from cattle in pens.

    PubMed

    McGinn, S M; Beauchemin, K A; Flesch, T K; Coates, T

    2009-01-01

    Accurate measurements of enteric methane (CH(4)) emissions from cattle (Bos taurus) are necessary to improve emission coefficients used in national emissions inventories, and to evaluate mitigation strategies. Our study was conducted to evaluate a novel approach that allowed near continuous CH(4) measurement from beef cattle confined in pens. The backward Lagrangian Stochastic (bLS) dispersion technique was used in conjunction with global position system (GPS) information from individual animals, to evaluate CH(4) emissions from pens of cattle. The dispersion technique was compared to estimates of CH(4) production using the SF(6) tracer technique. Sixty growing beef cattle were fed a diet containing 60% barley silage (dry matter basis) supplemented with either barley (Hordeum vulgare L.) grain or corn (Zea mays L.) distillers dried grains. The results show that daily CH(4) emissions were about 7% lower for the dispersion technique than for the tracer technique (185 vs. 199 g CH(4) animal(-1) d(-1)). The precision of the dispersion technique, relative to the SF(6) tracer technique, expressed by the Pearson coefficient was 0.76; the relative accuracy given by the concordance coefficient was 0.69. The bLS dispersion technique was able to detect differences (P < 0.05) due to diet and has the added advantage of measuring the pattern of CH(4) production during the 24-h period, with emissions ranging from 161 to 279 g CH(4) animal(-1) d(-1). Configuring the cattle as point sources resulted in more accurate CH(4) emissions than assuming a uniform area release from the pen surface. The results indicate that the bLS dispersion technique using cattle as point sources can be used to accurately measure enteric CH(4) from cattle and to evaluate the impact of dietary mitigation strategies. PMID:19643744

  1. OIL SPILL DISPERSANT EFFECTIVENESS PROTOCOL. II: PERFORMANCE OF THE REVISED PROTOCOL

    EPA Science Inventory

    The current U.S. Environmental Protection Agency (EPA) protocol for testing the effectiveness of dispersants for use in treating oil spills on the open water, the swirling flask test (SFT), has been found to give widely varying results in the hands of different testing laborator...

  2. Sensitivity of aerosol-cloud-precipitation interactions to autoconversion parameterization in WRF model

    NASA Astrophysics Data System (ADS)

    Xie, Xiaoning; Liu, Xiaodong

    2013-04-01

    Autoconversion process is an important bridge between aerosols, clouds, and precipitation, in that the change of the cloud microphysical properties by aerosols could influence the spatial and temporal changes of the surface precipitation, as well as the total precipitation amount. Three types of autoconversion parameterization are considered in our study including the Kessler scheme (Kessler, 1969), the KK scheme (Khairoutdinov and Kogan, 2000), and the Dispersion scheme (Liu et al., 2005). The Kessler scheme doesn't consider aerosol indirect effect and the KK scheme can study the aerosol indirect effect; while the Dispersion scheme can both consider the aerosol indirect effect and the influence of cloud droplet spectral dispersion. In this study, the aerosol effects on clouds and precipitation in mesoscale convective systems are investigated using the Weather Research and Forecast model (WRF) with the Morrison two-moment bulk microphysics scheme. Considering the different types of the autoconversion parameterization schemes including the Kessler scheme, the KK scheme, and the Dispersion scheme, a suite of sensitivity experiments are performed using an initial sounding data of the deep convective cloud system on 31 March 2005 in Beijing under different aerosol concentrations (varying from 50 cm-3 to 10000 cm-3). Numerical experiments in this study show that the aerosol induced precipitation change is strongly dependent on the autoconversion parameterization. For the Kessler scheme, the average cumulative precipitation is enhanced slightly with increasing aerosols. In the meantime, precipitation is reduced significantly with increasing aerosols for the KK scheme. The surface precipitation varies nonmonotonically for the Dispersion scheme, increasing with aerosols at lower concentration, while decreasing at higher concentration. These distinct trends in aerosol-induced precipitation are mainly due to the rain water content change under the different autoconversion

  3. Effect of surface coating with magnesium stearate via mechanical dry powder coating approach on the aerosol performance of micronized drug powders from dry powder inhalers.

    PubMed

    Zhou, Qi Tony; Qu, Li; Gengenbach, Thomas; Larson, Ian; Stewart, Peter J; Morton, David A V

    2013-03-01

    The objective of this study was to investigate the effect of particle surface coating with magnesium stearate on the aerosolization of dry powder inhaler formulations. Micronized salbutamol sulphate as a model drug was dry coated with magnesium stearate using a mechanofusion technique. The coating quality was characterized by X-ray photoelectron spectroscopy. Powder bulk and flow properties were assessed by bulk densities and shear cell measurements. The aerosol performance was studied by laser diffraction and supported by a twin-stage impinger. High degrees of coating coverage were achieved after mechanofusion, as measured by X-ray photoelectron spectroscopy. Concomitant significant increases occurred in powder bulk densities and in aerosol performance after coating. The apparent optimum performance corresponded with using 2% w/w magnesium stearate. In contrast, traditional blending resulted in no significant changes in either bulk or aerosolization behaviour compared to the untreated sample. It is believed that conventional low-shear blending provides insufficient energy levels to expose host micronized particle surfaces from agglomerates and to distribute guest coating material effectively for coating. A simple ultra-high-shear mechanical dry powder coating step was shown as highly effective in producing ultra-thin coatings on micronized powders and to substantially improve the powder aerosolization efficiency. PMID:23196863

  4. Improving the biogas production performance of municipal waste activated sludge via disperser induced microwave disintegration.

    PubMed

    Kavitha, S; Rajesh Banu, J; Vinoth Kumar, J; Rajkumar, M

    2016-10-01

    In this study, the influence of disperser induced microwave pretreatment was investigated to analyze the proficiency of floc disruption on subsequent disintegration and biodegradability process. Initially, the flocs in the sludge was disrupted through disperser at a specific energy input of 25.3kJ/kgTS. The upshot of the microwave disintegration presents that the solids reduction and solubilization of floc disrupted (disperser induced microwave pretreated) sludge was found to be 17.33% and 22% relatively greater than that achieved in microwave pretreated (9.3% and 16%) sludge alone. The biodegradability analysis, affords an evaluation of parameter confidence and correlation determination. The eventual biodegradability of microwave pretreated, and floc disrupted sludges were computed to be 0.15(gCOD/gCOD) and 0.28(gCOD/gCOD), respectively. An economic assessment of this study offers a positive net profit of about 104.8USD/ton of sludge in floc disrupted sample. PMID:26897472

  5. Study of all-optical clock recovery performance by the primary and the secondary temporal Talbot effects in a second-order dispersive medium

    NASA Astrophysics Data System (ADS)

    Oiwa, Masaki; Minami, Shunsuke; Tsuji, Kenichiro; Onodera, Noriaki; Saruwatari, Masatoshi

    2010-08-01

    We theoretically and experimentally study the all-optical clock recovery performance using the primary or the secondary temporal Talbot effects (PTTE or STTE, respectively) in a dispersive medium having the first-order dispersion together with the second-order dispersion (e.g., conventional single-mode fibers: SMFs). Our preliminary numerical simulations have indicated that the STTE-based all-optical clock recovery technique can improve double its performance as compared with the conventional PTTE-based technique when the second-order dispersion (dispersion slope) can be neglected. The following simulation results have revealed that the second-order dispersion, that the normal SMFs possess, limits the performance improvements in the STTE-based clock recovery, whereas the limited performance can be improved by appropriately compensating for the second-order dispersion. On the basis of our simulation results, experiments of the STTE-based clock recovery were conducted by compensating for the second-order dispersion of SMFs used as dispersive media. To be specific, SMFs' second-order dispersion has been reduced to the one-sixteenth of its original value by combining with the reverse-dispersion fibers (RDFs) which can provide the second-order dispersion of the opposite sign to the SMFs. As a result, the performance improvements in the STTE-based clock recovery was demonstrated so that the 10-GHz clear optical clock pulses were successfully recovered from 10-Gbit/s return-to-zero (RZ) pseudo-random bit sequence (PRBS) optical signals.

  6. New Mechanisms to Explain the Effects of Added Lactose Fines on the Dispersion Performance of Adhesive Mixtures for Inhalation

    PubMed Central

    Grasmeijer, Floris; Lexmond, Anne J.; van den Noort, Maarten; Hagedoorn, Paul; Hickey, Anthony J.; Frijlink, Henderik W.; de Boer, Anne H.

    2014-01-01

    Fine excipient particles or ‘fines’ have been shown to improve the dispersion performance of carrier-based formulations for dry powder inhalation. Mechanistic formulation studies have focussed mainly on explaining this positive effect. Previous studies have shown that higher drug contents may cause a decrease in dispersion performance, and there is no reason why this should not be true for fines with a similar shape, size and cohesiveness as drug particles. Therefore, the effects on drug detachment of ‘fine lactose fines’ (FLF, X50 = 1.95 µm) with a similar size and shape as micronised budesonide were studied and compared to those of ‘coarse lactose fines’ (CLF, X50 = 3.94 µm). Furthermore, interactions with the inhalation flow rate, the drug content and the mixing order were taken into account. The observed effects of FLF are comparable to drug content effects in that the detached drug fraction was decreased at low drug content and low flow rates but increased at higher flow rates. At high drug content the effects of added FLF were negligible. In contrast, CLF resulted in higher detached drug fractions at all flow rates and drug contents. The results from this study suggest that the effects of fines may be explained by two new mechanisms in addition to those previously proposed. Firstly, fines below a certain size may increase the effectiveness of press-on forces or cause the formation of strongly coherent fine particle networks on the carrier surface containing the drug particles. Secondly, when coarse enough, fines may prevent the formation of, or disrupt such fine particle networks, possibly through a lowering of their tensile strength. It is recommended that future mechanistic studies are based on the recognition that added fines may have any effect on dispersion performance, which is determined by the formulation and dispersion conditions. PMID:24489969

  7. Speciation analysis of mercury in water samples using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography.

    PubMed

    Gao, Zhongben; Ma, Xiaoguo

    2011-09-19

    A novel approach for preconcentration and speciation analysis of trace amount of mercury from water samples was proposed by dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography with diode array detection (HPLC-DAD). Mercury species (Hg(2+), methylmercury (MeHg(+)) and phenylmercury (PhHg(+))) were complexed with dithizone (DZ) to form hydrophobic chelates and then extracted into the fine drops of extraction solvent dispersed in the aqueous sample by dispersive solvent. After extraction, the sedimented phase was analyzed by HPLC-DAD. Some important parameters affecting the DLLME such as extraction solvent and dispersive solvent type and volume, concentration of dithizone solution, sample pH, extraction time and salt effect were investigated. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF(6)]) was found to be a suitable extractant for the chelates. Under the optimized conditions (extraction solvent: 70 μL of ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF(6)]); dispersive solvent: 0.75 mL of methanol containing dithizone (0.02%, m/v); pH: 4; extraction time: 5 min; and without salt addition), the limits of detection for Hg(2+), MeHg(+) and PhHg(+) were 0.32, 0.96 and 1.91 μg L(-1) (SN(-1)=3) respectively, and the relative standard deviation (RSD) was between 4.1 and 7.3% (n=5). Three real water samples (tap water, river water and lake water) spiked with mercury species were detected by the developed method, and the relative recoveries obtained for Hg(2+), MeHg(+) and PhHg(+) were 89.6-101.3%, 85.6-102.0% and 81.3-97.6%, respectively. PMID:21819859

  8. Determination of Sudan Residues in Sausage by Matrix Solid-Phase Dispersion and High-Performance Liquid Chromatography.

    PubMed

    Zhai, Yujuan; Cheng, Jianhua

    2015-09-01

    A method based on matrix solid-phase dispersion and high-performance liquid chromatography was applied to the determination of four Sudan red residues in sausage. The proposed method required only 0.5 g sample. The neutral alumina was used as the dispersant sorbent while n-hexane containing 10% (v/v) acetone was used as the eluting solvent. The recoveries in samples ranged from 76.4 to 111.0% and relative standard deviations were <10.2% with different spiked levels of 0.05-1.50 mg kg(-1). Detection and quantification limits were 5-19 and 18-39 μg kg(-1), respectively, with linear calibration curves extending up to 2.50 mg g(-1). The results demonstrate that the method can be successfully applied with acceptable recoveries to a broad range of target analytes within a diverse range of sausage. PMID:25838166

  9. TRAJECTORY OF AEROSOL DROPLETS FROM A SPRAYED BACTERIAL SUSPENSION

    EPA Science Inventory

    Simulated droplet trajectories of a polydispersed microbial aerosol in a laminar air flow regimen were compared with observed ispersal patterns of aerosolized Bacillus subtilis subsp. niger spores in quasilaminar airflow. imulated dispersal patterns could be explained in terms of...

  10. Spray-drying performance of a bench-top spray dryer for protein aerosol powder preparation.

    PubMed

    Maa, Y F; Nguyen, P A; Sit, K; Hsu, C C

    1998-11-01

    The objective of this work was to improve a bench-top spray dryer's efficiency in both production recovery and throughput for preparing protein aerosol powders. A Büchi mini-spray dryer was used to prepare the powders of recombinant humanized anti-IgE antibody. The resulting powder's physical properties such as particle size, residual moisture, and morphology, along with its recovery and production rate was the basis of this development work. Mass balance suggests that approximately 10-20% of powder was lost in the exhaust air, consisting primarily of particles less than 2 micrometer. Also, significant loss (20-30%) occurred in the cyclone. Attempts were made to improve product recovery in the receiving vessel using dual-cyclone configurations, different cyclone designs, cyclones with anti-static treatment, and different receiver designs. System modifications such as replacing the original bag-filter unit with a vacuum system effectively reduced drying air flow resistance, allowing the protein to be dried at a lower inlet air temperature and the production scale to be increased. We concluded that the modified spray-drying system is advantageous over the original bench-top spray dryer. This improvement will be beneficial to early-stage research and development involving high-valued protein powders. PMID:10099432

  11. ATR LEU Monothlic and Dispersed with 10B Loading Minimization Design – Neutronics Performance Analysis

    SciTech Connect

    G. S. Chang

    2001-10-01

    The Advanced Test Reactor (ATR), currently operating in the United States, is used for material testing at very high neutron fluxes. Powered with highly enriched uranium (HEU), the ATR has a maximum thermal power rating of 250 MWth. Because of the large test volumes located in high flux areas, the ATR is an ideal candidate for assessing the feasibility of converting HEU driven reactor cores to low-enriched uranium (LEU) cores. The present work investigates the optimized LEU Monolithic and Dispersed fuel with 10B loading minimization design and evaluates the subsequent neutronics operating effects of these optimized fuel designs. The MCNP ATR 1/8th core model was used to optimize the 235U and minimize the 10B loading in the LEU core, such that the differences in K-eff and heat flux profiles between the HEU and LEU cores were minimized. The fuel depletion methodology MCWO was used to calculate K eff versus effective full power days (EFPD) in this paper. The MCWO-calculated results for the optimized LEU Monolithic and Dispersed fuel cases demonstrated adequate excess reactivity such that the K-eff versus EFPD plot is similar to the ATR reference HEU case study. Each HEU fuel element contains 19 fuel plates with a fuel meat thickness of 0.508 mm (20 mil). In this work, the proposed LEU Monolithic (U-10Mo) core conversion case with nominal fuel meat thickness of 0.330 mm (13 mil) and 235U enrichment of 19.7 wt% is used to optimize the radial heat flux profile by varying the fuel meat thickness. The proposed LEU fuel meat varies from 0.203 mm (8.0 mil) to 0.254 mm (10.0 mil) at the inner four fuel plates (1-4) and outer four fuel plates (16-19). In addition, an optimized LEU dispersed (U7Mo) case with all the fuel meat thickness of 0.635 mm (25 mil) was also proposed. Then, for both Monolithic and dispersed cases, a burnable absorber – 10B, was added in the inner and outer plates to reduce the initial excess reactivity, and the higher to average ratio of the inner

  12. Performance Analysis of a New Coded TH-CDMA Scheme in Dispersive Infrared Channel with Additive Gaussian Noise

    NASA Astrophysics Data System (ADS)

    Hamdi, Mazda; Kenari, Masoumeh Nasiri

    2013-06-01

    We consider a time-hopping based multiple access scheme introduced in [1] for communication over dispersive infrared links, and evaluate its performance for correlator and matched filter receivers. In the investigated time-hopping code division multiple access (TH-CDMA) method, the transmitter benefits a low rate convolutional encoder. In this method, the bit interval is divided into Nc chips and the output of the encoder along with a PN sequence assigned to the user determines the position of the chip in which the optical pulse is transmitted. We evaluate the multiple access performance of the system for correlation receiver considering background noise which is modeled as White Gaussian noise due to its large intensity. For the correlation receiver, the results show that for a fixed processing gain, at high transmit power, where the multiple access interference has the dominant effect, the performance improves by the coding gain. But at low transmit power, in which the increase of coding gain leads to the decrease of the chip time, and consequently, to more corruption due to the channel dispersion, there exists an optimum value for the coding gain. However, for the matched filter, the performance always improves by the coding gain. The results show that the matched filter receiver outperforms the correlation receiver in the considered cases. Our results show that, for the same bandwidth and bit rate, the proposed system excels other multiple access techniques, like conventional CDMA and time hopping scheme.

  13. CHEMICAL OIL SPILL DISPERSANTS: UPDATE STATE-OF-THE-ART ON MECHANISMS OF ACTION AND FACTORS INFLUENCING PERFORMANCE WITH EMPHASIS ON LABORATORY STUDIES

    EPA Science Inventory

    The purpose of this report is to provide an updated review of information from the available literature for the mechanism of action of chemical dispersants, variables that affect dispersant performance, evaluation of a variety of laboratory tests designed to assess the performanc...

  14. Determination of polycyclic aromatic hydrocarbons using lab on valve dispersive liquid-liquid microextraction coupled to high performance chromatography.

    PubMed

    Fernández, M; Clavijo, S; Forteza, R; Cerdà, V

    2015-06-01

    In this work, dispersive liquid-liquid microextraction (DLLME) method was applied for high performance liquid chromatography (HPLC) determination of 15 PAHs in aqueous matrices.The extraction procedure was automated using a system of multisyringe flow injection analysis coupled to HPLC instrument with fluorescence detector. Factors affecting the extraction process, such as type and volume of extraction and dispersive solvent, extraction time and centrifugation step were investigated thoroughly and optimized utilizing factorial design. The best recovery was achieved using 100 µL of trichloroethylene as the extraction solvent and 900 µL of acetonitrile as the dispersive solvent.The results showed that extraction time has no effect on the recovery of PAHs. The enrichment factors of PAHs were in the range of 86-95 with limits of detection of 0.02-0.6 µg L(-1). The linearity was 0.2-600 µg L(-1) for different PAHs. The relative standard deviation (RSD) for intra- and inter-day of extraction of PAHs were in the range of 1.6-4.7 and 2.1-5.3, respectively, for five measurements.The developed method was used to assess the occurrence of 15 PAHs in tap water, rain waters and river surface waters samples. PMID:25863390

  15. Immobilization of Highly Dispersed Ag Nanoparticles on Carbon Nanotubes Using Electron-Assisted Reduction for Antibacterial Performance.

    PubMed

    Yan, Xiaoliang; Li, Sha; Bao, Jiehua; Zhang, Nan; Fan, Binbin; Li, Ruifeng; Liu, Xuguang; Pan, Yun-Xiang

    2016-07-13

    Silver nanoparticles (Ag NPs) supported on certain materials have been widely used as disinfectants. Yet, to date, the antibacterial activity of the supported Ag NPs is still far below optimum. This is mainly associated with the easy aggregation of Ag NPs on the supporting materials. Herein, an electron-assisted reduction (EAR) method, which is operated at temperatures as low as room temperature and without using any reduction reagent, was employed for immobilizing highly dispersed Ag NPs on aminated-CNTs (Ag/A-CNTs). The average Ag NPs size on the EAR-prepared Ag/A-CNTs is only 3.8 nm, which is much smaller than that on the Ag/A-CNTs fabricated from the traditional thermal calcination (25.5 nm). Compared with Ag/A-CNTs fabricated from traditional thermal calcination, EAR-prepared Ag/A-CNTs shows a much better antibacterial activity to E. coli/S. aureus and antifouling performance to P. subcordiformis/T. lepidoptera. This is mainly originated from the significantly enhanced Ag(+) ion releasing rate and highly dispersed Ag NPs with small size on the EAR-prepared Ag/A-CNTs. The findings from the present work are helpful for fabricating supported Ag NPs with small size and high dispersion for efficient antibacterial process. PMID:27327238

  16. Performance and economic risk evaluation of dispersed solar thermal power systems by Monte Carlo simulation

    NASA Technical Reports Server (NTRS)

    Manvi, R.; Fujita, T.

    1978-01-01

    A preliminary comparative evaluation of dispersed solar thermal power plants utilizing advanced technologies available in 1985-2000 time frame is under way at JPL. The solar power plants of 50 KWe to 10 MWe size are equipped with two axis tracking parabolic dish concentrator systems operating at temperatures in excess of 1000 F. The energy conversion schemes under consideration include advanced steam, open and closed cycle gas turbines, stirling, and combined cycle. The energy storage systems include advanced batteries, liquid metal, and chemical. This paper outlines a simple methodology for a probabilistic assessment of such systems. Sources of uncertainty in the development of advanced systems are identified, and a computer Monte Carlo simulation is exercised to permit an analysis of the tradeoffs of the risk of failure versus the potential for large gains. Frequency distribution of energy cost for several alternatives are presented.

  17. Dispersal ability and parasitisation performance of Trichogramma spp (Hymenoptera:Trichogrammatidae) in organic Basmati rice.

    PubMed

    Sharma, Sudhendu; Aggarwal, Naveen

    2015-11-01

    The dispersal/host searching capacity of Trichogramma chilonis Ishii and Trichogramma japonicum Ashmead was studied in organic Basmati rice during 2012 and 2013. Results showed that the level of parasitism was negatively correlated with the distance between host eggs and parasitoids' release point. Parasitisation rate was more (11.39-18.10% and 9.77-15.49% by T. chilonis and T. japonicum, respectively) near the release point (1-3m) with maximum parasitism at 1m by both the parasitoid species. A very low parasitism (0.05-0.47%) was recorded up to the distance of 8-9 m in two species. Among the two parasitoid species, T. chilonis showed higher parasitism (up to 18.10%) in different distance treatments in comparison to T. japonicum (up to 15.49%). PMID:26688971

  18. Influence of Copolymer Composition on In Vitro and In Vivo Performance of Celecoxib-PVP/VA Amorphous Solid Dispersions.

    PubMed

    Knopp, Matthias Manne; Nguyen, Julia Hoang; Mu, Huiling; Langguth, Peter; Rades, Thomas; Holm, René

    2016-03-01

    Previous studies suggested that an amorphous solid dispersion with a copolymer consisting of both hydrophobic and hydrophilic monomers could improve the dissolution profile of a poorly water-soluble drug compared to the crystalline form. Therefore, this study investigated the influence of the copolymer composition of polyvinylpyrrolidone/vinyl acetate (PVP/VA) on the non-sink in vitro dissolution behavior and in vivo performance of celecoxib (CCX) amorphous solid dispersions. The study showed that the hydrophilic monomer vinylpyrrolidone (VP) was responsible for the generation of CCX supersaturation whereas the hydrophobic monomer vinyl acetate (VA) was responsible for the stabilization of the supersaturated solution. For CCX, there was an optimal copolymer composition around 50-60% VP content where further replacement of VP monomers with VA monomers did not have any biopharmaceutical advantages. A linear relationship was found between the in vitro AUC(0-4h) and in vivo AUC(0-24h) for the CCX:PVP/VA systems, indicating that the non-sink in vitro dissolution method applied in this study was useful in predicting the in vivo performance. These results indicated that when formulating a poorly water-soluble drug as an amorphous solid dispersion using a copolymer, the copolymer composition has a significant influence on the dissolution profile and in vivo performance. Thus, the dissolution profile of a drug can theoretically be tailored by changing the monomer ratio of a copolymer with respect to the required in vivo plasma-concentration profile. As this ratio is likely to be drug dependent, determining the optimal ratio between the hydrophilic (dissolution enhancing) and hydrophobic (crystallization inhibiting) monomers for a given drug is imperative. PMID:26769250

  19. AERMOD: A Dispersion Model for Industrial Source Applications. Part II: Model Performance against 17 Field Study Databases.

    NASA Astrophysics Data System (ADS)

    Perry, Steven G.; Cimorelli, Alan J.; Paine, Robert J.; Brode, Roger W.; Weil, Jeffrey C.; Venkatram, Akula; Wilson, Robert B.; Lee, Russell F.; Peters, Warren D.

    2005-05-01

    The performance of the American Meteorological Society (AMS) and U.S. Environmental Protection Agency (EPA) Regulatory Model (AERMOD) Improvement Committee's applied air dispersion model against 17 field study databases is described. AERMOD is a steady-state plume model with significant improvements over commonly applied regulatory models. The databases are characterized, and the performance measures are described. Emphasis is placed on statistics that demonstrate the model's abilities to reproduce the upper end of the concentration distribution. This is most important for applied regulatory modeling. The field measurements are characterized by flat and complex terrain, urban and rural conditions, and elevated and surface releases with and without building wake effects. As is indicated by comparisons of modeled and observed concentration distributions, with few exceptions AERMOD's performance is superior to that of the other applied models tested. This is the second of two articles, with the first describing the model formulations.

  20. Determination of thiamphenicol in honey by dispersive liquid-liquid microextraction with high-performance liquid chromatography.

    PubMed

    Chen, Huaixia; Chen, Hui; Liao, Lei; Ying, Jun; Huang, Jianlin

    2010-07-01

    Dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography-variable wavelength detector (HPLC-VWD) was developed for extraction and determination of thiamphenicol (THA) in honey. A mixture of extraction solvent (30 microL 1,1,2,2-tetrachloroethane) and dispersive solvent (1.0 mL of acetonitrile) was rapidly injected into 5.00 mL sample solution for the formation of cloudy solution. The analyte in the sample was extracted into the fine droplets of C(2)H(2)Cl(4). After extraction, phase separation was performed by centrifugation, and the enriched analyte in the sedimented phase was determined by HPLC-VWD. Some important parameters, such as the kind and volume of extraction solvent and dispersive solvent, extraction time, sample solution pH, sample volume, and salt effect, were investigated and optimized. Under the optimum extraction condition, the method yielded a linear calibration curve in the concentration range from 3 to 2000 microg/kg for target analyte. The enrichment factors for THA was 87.9, and the limit of detection (S/N = 3) was 0.1 microg/kg. The relative standard deviation for the extraction of 10 microg/kg of THA was 6.2% (n = 6). The main advantages of DLLME-HPLC method are simplicity of operation, rapidity, low cost, high enrichment factor, high recovery, good repeatability, and extraction solvent volume at the microL level. Honey samples were successfully analyzed using the proposed method. PMID:20822659

  1. Performance of the analytical solutions for Taylor dispersion process in open channel flow

    NASA Astrophysics Data System (ADS)

    Zeng, L.; Wu, Zi; Fu, Xudong; Wang, Guangqian

    2015-09-01

    The present paper provides a systematical analysis for concentration distribution of Taylor dispersion in laminar open channel flow, seeking fundamental understandings for the physical process of solute transport that generally applies to natural rivers. As a continuation and a direct numerical verification of the previous theoretical work (Wu, Z., Chen, G.Q., 2014. Journal of Hydrology, 519: 1974-1984.), in this paper we attempt to understand that to what extent the obtained analytical solutions are valid for the multi-dimensional concentration distribution, which is vital for the key conclusion of the so-called slow-decaying transient effect. It is shown that as a first estimation, even asymptotically, the longitudinal skewness of the concentration distribution should be incorporated to predict the vertical concentration correctly. Thus the traditional truncation of the concentration expansion is considered to be insufficient for the first estimation. The analytical solution by the two-scale perturbation analysis with modifications up to the second order is shown to be a most economical solution to give a reasonably good prediction.

  2. High Performance Non-Dispersive X-Ray Spectrometers for Charge Exchange Measurements

    NASA Technical Reports Server (NTRS)

    Porter Frederick; Adams, J.; Beiersdorfer, P.; Brown, G. V.; Karkatoua, D.; Kelley, R. L.; Kilbourne, C. A.; Lautenagger, M.

    2010-01-01

    Currently, the only measurements of cosmological charge exchange have been made using low resolution, non-dispersive spectrometers like the PSPC on ROSAT and the CCD instruments on Chandra and XMM/Newton. However, upcoming cryogenic spectrometers on Astro-H and IXO will add vast new capabilities to investigate charge exchange in local objects such as comets and planetary atmospheres. They may also allow us to observe charge exchange in extra-solar objects such as galactic supernova remnants. With low spectral resolution instruments such as CCDs, x-ray emission due to charge exchange recombination really only provides information on the acceptor species, such as the solar wind. With the new breed of x-ray calorimeter instruments, emission from charge exchange becomes highly diagnostic allowing one to uniquely determine the acceptor species, ionization state, donor species and ionization state, and the relative velocity of the interaction. We will describe x-ray calorimeter instrumentation and its potential for charge exchange measurements in the near term. We will also touch on the instrumentation behind a decade of high resolution measurements of charge exchange using an x-ray calorimeter at the Lawrence Livermore National Laboratory.

  3. Improved Irradiation Performance of Uranium-Molybdenum/Aluminum Dispersion Fuel by Silicon Addition in Aluminum

    SciTech Connect

    Yeon Soo Kim; G. L. Hofman; A. B. Robinson; D. M. Wachs

    2013-10-01

    Uranium-molybdenum fuel particle dispersion in aluminum is a form of fuel under development for conversion of high-power research and test reactors from highly enriched to low-enriched uranium in the U.S. Global Threat Reduction Initiative program (also known as the Reduced Enrichment for Research and Test Reactors program). Extensive irradiation tests have been conducted to find a solution for problems caused by interaction layer growth and pore formation between U-Mo and Al. Adding a small amount of Si (up to [approximately]5 wt%) in the Al matrix was one of the proposed remedies. The effect of silicon addition in the Al matrix was examined using irradiation test results by comparing side-by-side samples with different Si additions. Interaction layer growth was progressively reduced with increasing Si addition to the matrix Al, up to 4.8 wt%. The Si addition also appeared to delay pore formation and growth between the U-Mo and Al.

  4. Determination of inulin-type fructooligosaccharides in edible plants by high-performance liquid chromatography with charged aerosol detector.

    PubMed

    Li, Jing; Hu, Dejun; Zong, Wanrong; Lv, Guangping; Zhao, Jing; Li, Shaoping

    2014-08-01

    Fructooligosaccharides (FOS), which are regarded as functional ingredients, are commonly classified as dietary fibers in many countries. However, few analytical methods for separation and analysis of individual FOS in plants, crops, and food products have been developed. In this study, a simple, rapid, and sensitive high performance liquid chromatography with charged aerosol detector (HPLC-CAD) method was developed for simultaneous determination of 11 inulin-type FOS with degree of polymerization (DP) 3-13 in different samples. The separation was performed on a Waters XBridge Amide column (4.6 × 250 mm i.d., 3.5 μm) with gradient elution. All calibration curves for investigated analytes showed good linear regression (R(2) > 0.9962). Their limits of detection (LOD) and quantification (LOQ) were in the ranges 0.4-0.6 μg/mL and 1.4-2.3 μg/mL, respectively. The recoveries ranged from 94.0% to 114.4%. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was applied to qualitative analysis of FOS in different samples. The developed method was successfully applied to analysis of 11 FOS in different samples of plants from Compositae, Campanulaceae, and Rubiaceae families. The developed HPLC-CAD nethod with microwave-assisted extraction can be used for quantitative analysis of FOS and is helpful for quality control of plants containing FOS. PMID:25034622

  5. Space shuttle launch vehicle performance trajectory, exchange ratios, and dispersion analysis

    NASA Technical Reports Server (NTRS)

    Toelle, R. G.; Blackwell, D. L.; Lott, L. N.

    1973-01-01

    A baseline space shuttle performance trajectory for Mission 3A launched from WTR has been generated. Design constraints of maximum dynamic pressure, longitudinal acceleration, and delivered payload were satisfied. Payload exchange ratios are presented with explanation on use. Design envelopes of dynamic pressure, SRB staging point, aerodynamic heating and flight performance reserves are calculated and included.

  6. Performance assessment of Large Eddy Simulation (LES) for modeling dispersion in an urban street canyon with tree planting

    NASA Astrophysics Data System (ADS)

    Moonen, P.; Gromke, C.; Dorer, V.

    2013-08-01

    The potential of a Large Eddy Simulation (LES) model to reliably predict near-field pollutant dispersion is assessed. To that extent, detailed time-resolved numerical simulations of coupled flow and dispersion are conducted for a street canyon with tree planting. Different crown porosities are considered. The model performance is assessed in several steps, ranging from a qualitative comparison to measured concentrations, over statistical data analysis by means of scatter plots and box plots, up to the calculation of objective validation metrics. The extensive validation effort highlights and quantifies notable features and shortcomings of the model, which would otherwise remain unnoticed. The model performance is found to be spatially non-uniform. Closer agreement with measurement data is achieved near the canyon ends than for the central part of the canyon, and typical model acceptance criteria are satisfied more easily for the leeward than for the windward canyon wall. This demonstrates the need for rigorous model evaluation. Only quality-assured models can be used with confidence to support assessment, planning and implementation of pollutant mitigation strategies.

  7. Modeling the Integrated Performance of Dispersion and Monolithic U-Mo Based Fuels

    SciTech Connect

    Daniel M. Wachs; Douglas E. Burkes; Steven L. Hayes; Karen Moore; Greg Miller; Gerard Hofman; Yeon Soo Kim

    2006-10-01

    The evaluation and prediction of integrated fuel performance is a critical component of the Reduced Enrichment for Research and Test Reactors (RERTR) program. The PLATE code is the primary tool being developed and used to perform these functions. The code is being modified to incorporate the most recent fuel/matrix interaction correlations as they become available for both aluminum and aluminum/silicon matrices. The code is also being adapted to treat cylindrical and square pin geometries to enhance the validation database by including the results gathered from various international partners. Additional modeling work has been initiated to evaluate the thermal and mechanical performance requirements unique to monolithic fuels during irradiation.

  8. Final Technical Report - High-Performance, Oxide-Dispersion-Strengthened Tubes for Production of Ethylene adn Other Industrial Chemicals

    SciTech Connect

    McKimpson, Marvin G.

    2006-04-06

    strengthened materials produced using mechanical alloying technology. To minimize cost, the bimetallic tube is produced by direct powder co-extrusion. This technology has potential for domestic energy savings of up to 4.1 trillion BTU/year (4.3 x 1015J/year) and a reduction of 370,000 tons (340,000 tonnes) of CO2 emissions in short-residence-time ethylene furnaces. This represents an energy savings and CO2 emissions reduction of about 3.3%. If the technology is also applied to other types of ethylene pyrolysis furnaces, total energy savings and CO2 emissions reductions could increase by up to five times. The work involved: Developing powder and consolidation processing protocols to produce an oxide-dispersion strengthened variant of Alloy 803 exhibiting creep strength comparable to Incoloy? Alloy MA956, Developing a direct powder co-extrusion protocol for fabricating co-extruded bimetallic Incoloy? Alloy MA956 / ODS Alloy 803 tubes, Characterizing the properties of the ODS Alloy 803 material, the welding characteristics of the bimetallic tubes, and the coking characteristics of the Incoloy? MA956 alloy, and Documenting the potential energy savings and user requirements for these bimetallic pyrolysis furnace tubes. The project demonstrated that oxide dispersion strengthened Alloy 803 can be produced successfully using conventional mechanical alloying technology. The oxide dispersion strengthened bimetallic radiant coil technology explored under this program has significant potential for energy savings and productivity improvements for domestic ethylene producers. In today's competitive market, however, domestic furnace manufacturers and ethylene producers appear reluctant to pay any cost premium for higher-performance coil materials offering either higher temperature capabilities or longer service life. Interest in oxide dispersion strengthened radiant coils is likely to increase if furnace and ethylene producers begin to focus more on increasing tube wall temperatures to

  9. Enhanced photorefractive performance in CdSe quantum-dot-dispersed poly(styrene-co-acrylonitrile) polymers

    SciTech Connect

    Li Xiangping; Embden, Joel van; Chon, James W. M.; Gu Min; Evans, Richard A.

    2010-06-21

    This paper reports on the enhanced photorefractive behavior of a CdSe quantum-dot-dispersed less expensive polymer of poly(styrene-co-acrylonitrile). The capability of CdSe quantum dots used as photosensitizers and the associated photorefractive performance are characterized through a photocurrent experiment and a two-beam coupling experiment, respectively. An enhanced two-beam coupling gain coefficient of 12.2 cm{sup -1} at 46 V/mum was observed owning to the reduced potential barrier. The photorefractive performance per CdSe quantum dot is three orders of magnitude higher than that in the sample sensitized by trinitrofluorenone in poly(styrene-co-acrylonitrile), and almost ten times higher than that in the CdSe quantum-dot-sensitized poly(N-vinylcarbazole) polymers.

  10. Organic aerosols

    SciTech Connect

    Penner, J.E.

    1994-01-01

    Organic aerosols scatter solar radiation. They may also either enhance or decrease concentrations of cloud condensation nuclei. This paper summarizes observed concentrations of aerosols in remote continental and marine locations and provides estimates for the sources of organic aerosol matter. The anthropogenic sources of organic aerosols may be as large as the anthropogenic sources of sulfate aerosols, implying a similar magnitude of direct forcing of climate. The source estimates are highly uncertain and subject to revision in the future. A slow secondary source of organic aerosols of unknown origin may contribute to the observed oceanic concentrations. The role of organic aerosols acting as cloud condensation nuclei (CCN) is described and it is concluded that they may either enhance or decrease the ability of anthropogenic sulfate aerosols to act as CCN.

  11. Influence of surface characteristics of modified glass beads as model carriers in dry powder inhalers (DPIs) on the aerosolization performance.

    PubMed

    Zellnitz, Sarah; Schroettner, Hartmuth; Urbanetz, Nora Anne

    2015-01-01

    The aim of this work is to investigate the effect of surface characteristics (surface roughness and specific surface area) of surface-modified glass beads as model carriers in dry powder inhalers (DPIs) on the aerosolization, and thus, the in vitro respirable fraction often referred to as fine particle fraction (FPF). By processing glass beads in a ball mill with different grinding materials (quartz and tungsten carbide) and varying grinding time (4 h and 8 h), and by plasma etching for 1 min, glass beads with different shades of surface roughness and increased surface area were prepared. Compared with untreated glass beads, the surface-modified rough glass beads show increased FPFs. The drug detachment from the modified glass beads is also more reproducible than from untreated glass beads indicated by lower standard deviations for the FPFs of the modified glass beads. Moreover, the FPF of the modified glass beads correlates with their surface characteristics. The higher the surface roughness and the higher the specific surface area of the glass beads the higher is the FPF. Thus, surface-modified glass beads make an ideal carrier for tailoring the performance of DPIs in the therapy of asthma and chronically obstructive pulmonary diseases. PMID:25632978

  12. Quantitative analysis of aliphatic amines in urban aerosols based on online derivatization and high performance liquid chromatography.

    PubMed

    Huang, Xiongfeng; Deng, Congrui; Zhuang, Guoshun; Lin, Jing; Xiao, Mengxin

    2016-07-13

    A method combining online derivatization with high performance liquid chromatography/fluorescence detection was developed for the determination of seven aliphatic amines (ethanolamine, methylamine, ethylamine, propylamine, butylamine, pentylamine and hexylamine) in urban aerosols. The collected amines were online derivatized with o-phthalaldehyde to form highly fluorescent sulfonatoisoindole derivatives. The derivatives were completely separated in 13 min through gradient elution and detected by fluorescence detection at an excitation wavelength of 334 nm and an emission wavelength of 443 nm. Under the optimized conditions, the relative standard derivations (RSDs) of all detected amines were 0.02-2.03% and 1.04-1.52% for the retention time and peak area, respectively. Excellent linearity was achieved for each analyte, ranging from 5 μg L(-1) to 1000 μg L(-1) (R(2) > 0.99). The detection limits for all analytes were below 1.1 μg L(-1). The proposed method was used to analyze aliphatic amines in 35 samples of urban PM2.5 collected in Shanghai and was found to be suitable for the determination of particulate aliphatic amines at ng m(-3) levels in ambient air. Based on our measurements, ethanolamine and methylamine were the most abundant species on average in Shanghai during dry and wet seasons. The highest concentration was 15.3 ng m(-3) for ethanolamine and 13.2 ng m(-3) for methylamine. PMID:27272699

  13. Determination of triazine herbicides in environmental samples by dispersive liquid-liquid microextraction coupled with high performance liquid chromatography.

    PubMed

    Wang, Chun; Ji, Shujing; Wu, Qiuhua; Wu, Chunxia; Wang, Zhi

    2011-10-01

    A simple, rapid, efficient, and environmentally friendly method for the determination of five triazine herbicides in water and soil samples was developed by using dispersive liquid-liquid microextraction (DLLME), coupled with high performance liquid chromatography-diode array detection (HPLC-DAD). The water samples were directly used for DLLME extraction. For soil samples, the target analytes were first extracted by water-methanol (99:1, v/v). In the DLLME extraction method, chloroform was used as an extraction solvent, and acetonitrile as a dispersive solvent. Under the optimum conditions, the enrichment factors of DLLME were in the range between 183-221. The linearity of the method was obtained in the range of 0.5-200 ng/mL for the water sample analysis, and 1-200 ng/g for the soil samples, respectively. The correlation coefficients ranged from 0.9968 to 0.9999. The limits of detection were 0.05-0.1 ng/mL for the water samples, and 0.1-0.2 ng/g for the soil samples. The proposed method has been successfully applied to the analysis of target triazine herbicides (simazin, atrazine, prometon, ametryn, and prometryn) in water and soil samples with satisfactory results. PMID:22586245

  14. Design and performance evaluation of a dispersion compensation unit using several chirping functions in a tanh apodized FBG and comparison with dispersion compensation fiber.

    PubMed

    Mohammed, Nazmi A; Solaiman, Mohammad; Aly, Moustafa H

    2014-10-10

    In this work, various dispersion compensation methods are designed and evaluated to search for a cost-effective technique with remarkable dispersion compensation and a good pulse shape. The techniques consist of different chirp functions applied to a tanh fiber Bragg grating (FBG), a dispersion compensation fiber (DCF), and a DCF merged with an optimized linearly chirped tanh FBG (joint technique). The techniques are evaluated using a standard 10 Gb/s optical link over a 100 km long haul. The linear chirp function is the most appropriate choice of chirping function, with a pulse width reduction percentage (PWRP) of 75.15%, lower price, and poor pulse shape. The DCF yields an enhanced PWRP of 93.34% with a better pulse quality; however, it is the most costly of the evaluated techniques. Finally, the joint technique achieved the optimum PWRP (96.36%) among all the evaluated techniques and exhibited a remarkable pulse shape; it is less costly than the DCF, but more expensive than the chirped tanh FBG. PMID:25322426

  15. CHEMICAL OIL SPILL DISPERSANTS: UPDATE STATE-OF-THE- ART ON MECHANISM OF ACTION AND LABORATORY TESTING FOR PERFORMANCE

    EPA Science Inventory

    Chemical dispersants are formulations designed to facilitate dispersion of an oil slick into small droplets that disperse to non-problematic concentrations in an underlying water column. This project had two primary objectives: (1) update information on mechanisms of action of ...

  16. The enhanced aerosol performance of salbutamol from dry powders containing engineered mannitol as excipient.

    PubMed

    Kaialy, Waseem; Martin, Gary P; Ticehurst, Martyn D; Momin, Mohammed N; Nokhodchi, Ali

    2010-06-15

    The aim of the present study was to investigate the effect of crystallising mannitol from different binary mixtures of acetone/water on the resultant physical properties and to determine the effects of any changes on in vitro aerosolisation performance, when the different mannitol crystals were used as a carrier in dry powder inhaler formulations containing salbutamol sulphate. Mannitol particles were crystallised under controlled conditions by dissolving the sugar in water and precipitating the sugar using binary mixtures of acetone/water in different percentages as anti-solvent media. For comparison purposes the physical properties and deposition behaviour of commercially available mannitol were also studied. SEM showed that all crystallised mannitol particles were more elongated than the commercial mannitol. Solid state studies revealed that commercial mannitol and mannitol crystallised using acetone in the presence of 10-25% v/v water as anti-solvent was beta-polymorphic form whereas mannitol crystallised in the presence of a small amount of water (0-7.5%) was the alpha-form. All the crystallised mannitol samples showed poor flowability. Nevertheless, the powdered crystallised mannitol and commercial samples were blended with salbutamol in the ratio 67.5:1. The aerosolisation performance of the formulations containing the engineered mannitol (evaluated using Multi Stage Liquid Impinger) was considerably better than that of the commercial mannitol formulation (the fine particle fraction was increased from 15.42% to 33.07-43.99%, for the formulations containing crystallised mannitol). Generally, carriers having a high tapped density and high fraction of fine carrier particles produced a high FPF. The improvement in the DPI performance could be attributed to the presence of elongated carrier particles with smooth surfaces since these are believed to have less adhesive forces between carrier and the drug resulting in easier detachment of the drug during the

  17. Emission, Dispersion, Transformation, and Deposition of Asian Particulates Over the Western Pacific Ocean

    SciTech Connect

    Turco, Richard P.

    2005-02-28

    In this project we developed and applied a coupled three-dimensional meteorology/chemistry/microphysics model to study the patterns of aerosol dispersion and deposition in the western Pacific area; carried out a series of detailed regional aerosol simulations to test the ability of models to treat emission, dispersion and removal processes prior to long-range transport; calculated and analyzed trajectories that originate in Asian dust source regions and reach the Pacific Basin; performed detailed simulations of regional and trans-Pacific transport, as well as the microphysical and chemical properties, of aerosols in the Asia-Pacific region to quantify processes that control the emission, dispersion and removal of particles; and assessed the contributions of regional-scale Asian particulate sources to the deposition of pollutants onto surface waters. The transport and deposition of aerosols and vapors were found to be strongly controlled by large and synoptic scale meteorology, convection, turbulence, and precipitation, as well as strong interactions between surface conditions and topographical features. The present analysis suggests that accurate representations of aerosol sources, transport and deposition can be obtained using a comprehensive modeling approach.

  18. Performance improvement of FSO/CDMA systems over dispersive turbulence channel using multi-wavelength PPM signaling.

    PubMed

    Dang, Ngoc T; Pham, Anh T

    2012-11-19

    Previous studies show that, compared to on-off keying (OOK) signaling, pulse-position modulation (PPM) is favorable in FSO/CDMA systems thanks to its energy efficiency and simple detection. Nevertheless, when the system bit rate increases and the transmission distance is far, the FSO/CDMA systems using PPM signaling critically suffer from the impact of pulse broadening caused by dispersion, especially when the modulation level is high. In this paper, we therefore propose to use multi-wavelength PPM (MWPPM) signaling to overcome the limitation of PPM. To further improve the system performance, avalanche photodiode (APD) is also used. The performance of the proposed system is theoretically analyzed using a realistic model of Gaussian pulse propagation. To model the impact of intensity fluctuation caused by the atmospheric turbulence, the log-normal channel is used. We find that, by using MWPPM, the effects of both intensity fluctuation and pulse broadening are mitigated, the BER is therefore significantly improved. Additionally, we quantitatively show that the system performance is further improved by using APD, especially when the average APD gain is chosen properly. PMID:23187533

  19. Technical study of some major parameters influencing the performance of an aerosol delivery equipment suitable for calves.

    PubMed

    Genicot, B; Peckova, M; Close, R; Lindsey, J K; Lambert, P; Lekeux, P

    1994-01-01

    Aerosol delivery equipment, suitable for the treatment of bovine respiratory dysfunctions and including 2 parallelly positioned jet nebulizers, was studied in depth in order to determine the optimal working conditions in the field. Indeed, some factors might reasonably alter the performance of this equipment. Among these factors, the influences of the parallel position of jet nebulizers (in order to accommodate the breathing requirements of the cattle and achieve a rapid treatment), of the long feed pipe delivering compressed air (in order to keep the animal away from the compressor unit), and finally of the ambient temperature were studied, this equipment being essentially used during the winter season. This equipment could accommodate the breathing needs of cattle weighing up to 225 kg if a pressure of 600 kPa was developed upstream to the nebulizers. The rate of atomization was significantly reduced when working at ambient air temperatures (272.25 K < T < 274.65 K) close to those encountered in winter. This was especially true when pressure upstream to the nebulizers did not exceed 500 kPa. The immersion of the feed pipe for compressed air in hot water led to an increase in the rate of atomization without raising evaporative water losses, and reduced the drop in temperature in the nebulizer solution. Finally, the rate of atomization significantly increased when the face mask including the nebulizers was maintained so that the nebulizers were in a vertical position or at an angle not less than 60 degrees with respect to the ground. PMID:7951349

  20. High performance liquid chromatography-charged aerosol detection applying an inverse gradient for quantification of rhamnolipid biosurfactants.

    PubMed

    Behrens, Beate; Baune, Matthias; Jungkeit, Janek; Tiso, Till; Blank, Lars M; Hayen, Heiko

    2016-07-15

    A method using high performance liquid chromatography coupled to charged-aerosol detection (HPLC-CAD) was developed for the quantification of rhamnolipid biosurfactants. Qualitative sample composition was determined by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The relative quantification of different derivatives of rhamnolipids including di-rhamnolipids, mono-rhamnolipids, and their precursors 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) differed for two compared LC-MS instruments and revealed instrument dependent responses. Our here reported HPLC-CAD method provides uniform response. An inverse gradient was applied for the absolute quantification of rhamnolipid congeners to account for the detector's dependency on the solvent composition. The CAD produces a uniform response not only for the analytes but also for structurally different (nonvolatile) compounds. It was demonstrated that n-dodecyl-β-d-maltoside or deoxycholic acid can be used as alternative standards. The method of HPLC-ultra violet (UV) detection after a derivatization of rhamnolipids and HAAs to their corresponding phenacyl esters confirmed the obtained results but required additional, laborious sample preparation steps. Sensitivity determined as limit of detection and limit of quantification for four mono-rhamnolipids was in the range of 0.3-1.0 and 1.2-2.0μg/mL, respectively, for HPLC-CAD and 0.4 and 1.5μg/mL, respectively, for HPLC-UV. Linearity for HPLC-CAD was at least 0.996 (R(2)) in the calibrated range of about 1-200μg/mL. Hence, the here presented HPLC-CAD method allows absolute quantification of rhamnolipids and derivatives. PMID:27283098

  1. Evaluation of the performance of the N95-companion: effects of filter penetration and comparison with other aerosol instruments.

    PubMed

    Rengasamy, Samy; Eimer, Benjamin C; Shaffer, Ronald E

    2012-01-01

    Fit factor is the ratio of the particle concentration outside (C(out)) to the inside (C(in)) of the respirator and assumes that filter penetration is negligible. For Class-95 respirators, concerns were raised that filter penetration could bias fit test measurements. The TSI N95-Companion was designed to overcome this limitation by measuring only 40-60 nm size particles. Recent research has shown that particles in this size range are the most penetrating for respirators containing electrostic filter media. The goal of this study was to better understand the performance of the N95-Companion by assessing the impact of filter penetration and by comparing C(out)/C(in) ratios measured by other aerosol instruments (nano-Differential Mobility Analyzer/Ultrafine Condensation Particle Counter (nano-DMA/UCPC) and the TSI PortaCount Plus) using N95 filtering facepiece respirators sealed to a manikin and with intentionally created leaks. Results confirmed that 40-60 nm-diameter size room air particles were most penetrating for the respirators tested. A nonlinear relationship was found between the N95-Companion-measured C(out)/C(in) ratios and the other instruments at the sealed condition and at the small leak sizes because the N95-Companion measures only charged particles that are preferentially captured by the electrostic filter media, while the other instrument configurations also measure uncharged particles, which are captured less efficiently. The C(out)/C(in) ratios from the N95-Companion for experiments conducted under sealed condition suggest that filter penetration of negatively charged 40-60 nm size particles was less than 0.05%. Thus, the N95-Companion measured C(out)/C(in) ratios are due primarily to particle penetration through leakage, not through filter media, while the C(out)/C(in) ratios for the PortaCount, nano-DMA/UCPC, and UCPC result from a combination of face seal leakage and filter penetration. PMID:22642759

  2. Effect of dispersion method and CNT loading on the quality and performance of nanocomposite soy protein/CNTs adhesive for wood application

    NASA Astrophysics Data System (ADS)

    Afolabi, Ayo Samuel; Oluwafolakemi Sadare, Olawumi; Olawale Daramola, Michael

    2016-09-01

    In this article the effect of dispersion method and carbon nanotubes (CNTs) loading on the quality and performance of a nanocomposite adhesive is reported. The nanocomposite soy protein isolate adhesive was successfully developed by incorporating CNTs into the soy protein isolate (SPI) for enhanced bond strength and water resistance. Dispersion methods, namely mechanical (shear) mixing and mechanical/sonication were employed to aid good dispersion and interfacial interaction between soy protein matrix and the carbon nanofillers during the preparation of the adhesive. The concentration of the CNT was varied from 0.1–0.7 wt% in the nanocomposite adhesive. The morphology and the surface chemistry of the adhesives were checked with SEM and FTIR, respectively. The shear strength of the developed adhesives was investigated according to European standard (EN-204) for interior wood application on a tensile testing machine. The morphological structure of the nanocomposite adhesive obtained from SEM images showed homogeneous dispersion of CNTs in SPI using the two dispersion methods; shear mixing and sonication/shear mixing. Fourier transform infrared spectra showed chemical functionalities and successful interaction between CNTs and SPI adhesive. Thermogravimetric profile of the adhesive samples showed that the newly developed nanocomposite adhesive was thermally stable at a temperature up to about 600 °C at a higher percentage loading of 0.5 wt% CNTs. The result showed that sonication method of dispersion of CNTs into the SPI adhesive had a higher shear strength compared to the mechanical method of dispersion both at dry and wet state.

  3. Performance evaluation of AERMOD, CALPUFF, and legacy air dispersion models using the Winter Validation Tracer Study dataset

    NASA Astrophysics Data System (ADS)

    Rood, Arthur S.

    2014-06-01

    The performance of the steady-state air dispersion models AERMOD and Industrial Source Complex 2 (ISC2), and Lagrangian puff models CALPUFF and RATCHET were evaluated using the Winter Validation Tracer Study dataset. The Winter Validation Tracer Study was performed in February 1991 at the former Rocky Flats Environmental Technology Site near Denver, Colorado. Twelve, 11-h tests were conducted where a conservative tracer was released and measured hourly at 140 samplers in concentric rings 8 km and 16 km from the release point. Performance objectives were unpaired maximum one- and nine-hour average concentration, location of plume maximum, plume impact area, arc-integrated concentration, unpaired nine-hour average concentration, and paired ensemble means. Performance objectives were aimed at addressing regulatory compliance, and dose reconstruction assessment questions. The objective of regulatory compliance is not to underestimate maximum concentrations whereas for dose reconstruction, the objective is an unbiased estimate of concentration in space and time. Performance measures included the fractional bias, normalized mean square error, geometric mean, geometric mean variance, correlation coefficient, and fraction of observations within a factor of two. The Lagrangian puff models tended to exhibit the smallest variance, highest correlation, and highest number of predictions within a factor of two compared to the steady-state models at both the 8-km and 16-km distance. Maximum one- and nine-hour average concentrations were less likely to be under-predicted by the steady-state models compared to the Lagrangian puff models. The characteristic of the steady-state models not to under-predict maximum concentrations make them well suited for regulatory compliance demonstration, whereas the Lagrangian puff models are better suited for dose reconstruction and long range transport.

  4. Analysis of drugs of abuse in human plasma by dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    PubMed

    Fernández, P; Regenjo, M; Bermejo, A M; Fernández, A M; Lorenzo, R A; Carro, A M

    2015-04-01

    Opioids and cocaine are widely used at present, both for recreational purposes and as drugs of abuse. This raises the need to develop new analytical methods specifically designed for the simultaneous detection of several drugs of abuse in biological samples. In this work, dispersive liquid-liquid microextraction (DLLME) was assessed as a new sample treatment for the simultaneous extraction of morphine (MOR), 6-acetylmorphine (6AM), cocaine (COC), benzoylecgonine (BZE) and methadone (MET) from human plasma. Preliminary assays were done before developing an experimental design based on a Uniform Network Doehlert which allowed the optimum extraction conditions to be identified, namely: a volume of extractant solvent (chloroform) and dispersant solvent (acetonitrile) of 220 µl and 3.2 ml, respectively; 0.2 g of NaCl as a salting-out additive; pH 10.6 and ultrasound stirring for 3.5 min. The resulting extracts were analyzed by high-performance liquid chromatography with photodiode array detection (HPLC-PDA), using an XBridge® RP18 column (250 × 4.6 mm i.d., 5 µm particle size). Calibration graphs were linear over the concentration range 0.1-10 µg ml⁻¹, and detection limits ranged from 13.9 to 28.5 ng ml⁻¹. Precision calculated at three different concentration levels in plasma was included in the range 0.1-6.8% RSD. Recoveries of the five drugs were all higher than 84% on average. Finally the proposed method was successfully applied to 22 plasma samples from heroin, cocaine and/or methadone users, and the most frequently detected drug was benzoylecgonine, followed by methadone, cocaine and morphine. PMID:25091865

  5. Aerosol generation by raindrop impact on soil

    NASA Astrophysics Data System (ADS)

    Joung, Young Soo; Buie, Cullen R.

    2015-01-01

    Aerosols are investigated because of their significant impact on the environment and human health. To date, windblown dust and sea salt from sea spray through bursting bubbles have been considered the chief mechanisms of environmental aerosol dispersion. Here we investigate aerosol generation from droplets hitting wettable porous surfaces including various classifications of soil. We demonstrate that droplets can release aerosols when they influence porous surfaces, and these aerosols can deliver elements of the porous medium to the environment. Experiments on various porous media including soil and engineering materials reveal that knowledge of the surface properties and impact conditions can be used to predict when frenzied aerosol generation will occur. This study highlights new phenomena associated with droplets on porous media that could have implications for the investigation of aerosol generation in the environment.

  6. Montelukast-loaded nanostructured lipid carriers: part II pulmonary drug delivery and in vitro-in vivo aerosol performance.

    PubMed

    Patil-Gadhe, Arpana; Kyadarkunte, Abhay; Patole, Milind; Pokharkar, Varsha

    2014-09-01

    The aim of the present study was to establish the potential of montelukast loaded nanostructured lipid carrier (MNLC) for pulmonary application. The formulated nanoparticles were evaluated in vitro for aerodynamic characterization and in vivo for pulmokinetics in Wistar rats. The in vitro cytotoxicity was performed on A549 cell line and compared with montelukast-aqueous solution. MNLC was prepared with montelukast (0.2%), Precirol ATO5 (solid lipid), and Capryol-90 (liquid lipid) in the ratio of 7:3 using melt-emulsification-homogenization method. dl-Pyrrolidonecarboxylic acid salt of l-cocyl arginine ethyl ester (CAE), a biodegradable surfactant in the concentration of 1% was used to stabilize the nanoparticles. The particle size and encapsulation efficiency (EE) were 184.6 ± 2.7 nm and >95%, respectively. MNLC-Dry powder for inhalation (DPI) was prepared by lyophilization using 3% mannitol as cryoprotectant and carrier. MNLC-DPI was evaluated for flow, crystallographic and thermal properties. Mass median diameters (MMD) and density for MNLC-DPI were found to be 15.1 ± 1.4 μm and 0.051 ± 0.002 g/cc, respectively. In vitro aerosol performance study indicated more than 95% of the emitted dose (ED) at both the flow rates studied. Mass median aerodynamic diameters (MMAD) of 3.24 ± 0.67 μm with 69.98 ± 1.9% fine particle fraction (FPF) were obtained at 30 L/min flow rate, whereas at 60 L/min MMAD and FPF were found to be 2.83 ± 0.46 μm and 90.22 ± 2.6%, respectively. In vitro cytotoxicity study on A549 cells revealed higher safety of MNLC than pure drug. The pulmonary pharmacokinetic study demonstrated improved bioavailability, longer residence of drug in the lung and targeting factor of 11.76 for MNLC as compared to montelukast-aqueous solution. Thus, the results of the study demonstrated the potential of montelukast lipidic nanoparticulate formulation to improve the efficacy with reduced toxicity leading to better performance of drug as MNLC-DPI for

  7. Trace matrix solid phase dispersion using a molecular sieve as the sorbent for the determination of flavonoids in fruit peels by ultra-performance liquid chromatography.

    PubMed

    Cao, Wan; Hu, Shuai-Shuai; Ye, Li-Hong; Cao, Jun; Pang, Xiao-Qing; Xu, Jing-Jing

    2016-01-01

    A simple, rapid, and highly selective trace matrix solid phase dispersion (MSPD) technique, coupled with ultra-performance liquid chromatography-ultraviolet detection, was proposed for extracting flavonoids from orange fruit peel matrices. Molecular sieve SBA-15 was applied for the first time as a solid support in trace MSPD. Parameters, such as the type of dispersant, mass ratio of the sample to the dispersant, grinding time, and elution pH, were optimized in detail. The optimal extraction conditions involved dispersing a powdered fruit peel sample (25 mg) into 25mg of SBA-15 and then eluting the target analytes with 500 μL of methanol. A satisfactory linearity (r(2) > 0.9990) was obtained, and the calculated limits of detection reached 0.02-0.03 μg/mL for the compounds. The results showed that the method developed was successfully applied to determine the content of flavonoids in complex fruit peel matrices. PMID:26212999

  8. Design and Performance of a TES X-ray Microcalorimeter Array for Energy Dispersive Spectroscopy on Scanning Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Muramatsu, Haruka; Nagayoshi, K.; Hayashi, T.; Sakai, K.; Yamamoto, R.; Mitsuda, K.; Yamasaki, N. Y.; Maehata, K.; Hara, T.

    2016-07-01

    We discuss the design and performance of a transition edge sensor (TES) X-ray microcalorimeter array for scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS). The TES X-ray microcalorimeter has better energy resolution compared to conventional silicon drift detector and STEM-EDS utilizing a TES detector makes it possible to map the distribution of elements on a specimen in addition to analyze the composition. The requirement for a TES detector is a high counting rate (>20 kcps), wide energy band (0.5-15 keV) and good energy resolution (<10 eV) full width at half maximum. The major improvement of this development is to increase the maximum counting rate. In order to accommodate the high counting rate, we adopted an 8 × 8 format, 64-pixel array and common biasing scheme for the readout method. We did all design and fabrication of the device in house. With the device we have fabricated most recently, the pulse decay time is 40 \\upmu s which is expected to achieve 50 kcps. For a single pixel, the measured energy resolution was 7.8 eV at 5.9 keV. This device satisfies the requirements of counting rate and energy resolution, although several issues remain where the performance must be confirmed.

  9. Design and Performance of a TES X-ray Microcalorimeter Array for Energy Dispersive Spectroscopy on Scanning Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Muramatsu, Haruka; Nagayoshi, K.; Hayashi, T.; Sakai, K.; Yamamoto, R.; Mitsuda, K.; Yamasaki, N. Y.; Maehata, K.; Hara, T.

    2016-02-01

    We discuss the design and performance of a transition edge sensor (TES) X-ray microcalorimeter array for scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS). The TES X-ray microcalorimeter has better energy resolution compared to conventional silicon drift detector and STEM-EDS utilizing a TES detector makes it possible to map the distribution of elements on a specimen in addition to analyze the composition. The requirement for a TES detector is a high counting rate (> 20 kcps), wide energy band (0.5-15 keV) and good energy resolution (< 10 eV) full width at half maximum. The major improvement of this development is to increase the maximum counting rate. In order to accommodate the high counting rate, we adopted an 8 × 8 format, 64-pixel array and common biasing scheme for the readout method. We did all design and fabrication of the device in house. With the device we have fabricated most recently, the pulse decay time is 40 \\upmu s which is expected to achieve 50 kcps. For a single pixel, the measured energy resolution was 7.8 eV at 5.9 keV. This device satisfies the requirements of counting rate and energy resolution, although several issues remain where the performance must be confirmed.

  10. Design and Performance of a TES X-ray Microcalorimeter Array for Energy Dispersive Spectroscopy on Scanning Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Muramatsu, Haruka; Nagayoshi, K.; Hayashi, T.; Sakai, K.; Yamamoto, R.; Mitsuda, K.; Yamasaki, N. Y.; Maehata, K.; Hara, T.

    2016-07-01

    We discuss the design and performance of a transition edge sensor (TES) X-ray microcalorimeter array for scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS). The TES X-ray microcalorimeter has better energy resolution compared to conventional silicon drift detector and STEM-EDS utilizing a TES detector makes it possible to map the distribution of elements on a specimen in addition to analyze the composition. The requirement for a TES detector is a high counting rate (>20 kcps), wide energy band (0.5-15 keV) and good energy resolution (<10 eV) full width at half maximum. The major improvement of this development is to increase the maximum counting rate. In order to accommodate the high counting rate, we adopted an 8 × 8 format, 64-pixel array and common biasing scheme for the readout method. We did all design and fabrication of the device in house. With the device we have fabricated most recently, the pulse decay time is 40 μs which is expected to achieve 50 kcps. For a single pixel, the measured energy resolution was 7.8 eV at 5.9 keV. This device satisfies the requirements of counting rate and energy resolution, although several issues remain where the performance must be confirmed.

  11. A high performance semi-crystalline electrostatic stabilizer for aqueous dispersion prepregging: Poly(pyridine ether-co-ether ether ketone)

    SciTech Connect

    Brink, A.E.; Lin, M.C.; Riffle, J.S. |

    1993-12-31

    Aqueous dispersion prepregging is a relatively new, alternate method for processing polymer matrix composites, which could potentially circumvent many of the environmental and processing problems prominent in melt or solution prepregging. However, this method requires the high performance thermoplastic matrix resin to be in the form of small particles dispersed in a stable aqueous suspension. The preparation of submicron particles of the high performance semicrystalline poly(ether ether ketone) has previously been reported (Polymer, accepted 1992). Suspensions of these particles in water were demonstrated, but the suspending agents used were not thermally stable materials. This paper discusses the development of a high performance stabilizer which can be used for suspending PEEK particles in water (forming stable colloids), thereby facilitating the development of processes for aqueous dispersion prepegging. The stabilizer is a copolymer formed from 4,4`-difluoro (N-benzohydroxylidene aniline), 2,6-dichloropyridine, and hydroquinone.

  12. Whole-body nanoparticle aerosol inhalation exposures.

    PubMed

    Yi, Jinghai; Chen, Bean T; Schwegler-Berry, Diane; Frazer, Dave; Castranova, Vince; McBride, Carroll; Knuckles, Travis L; Stapleton, Phoebe A; Minarchick, Valerie C; Nurkiewicz, Timothy R

    2013-01-01

    Inhalation is the most likely exposure route for individuals working with aerosolizable engineered nano-materials (ENM). To properly perform nanoparticle inhalation toxicology studies, the aerosols in a chamber housing the experimental animals must have: 1) a steady concentration maintained at a desired level for the entire exposure period; 2) a homogenous composition free of contaminants; and 3) a stable size distribution with a geometric mean diameter < 200 nm and a geometric standard deviation σg < 2.5 (5). The generation of aerosols containing nanoparticles is quite challenging because nanoparticles easily agglomerate. This is largely due to very strong inter-particle forces and the formation of large fractal structures in tens or hundreds of microns in size (6), which are difficult to be broken up. Several common aerosol generators, including nebulizers, fluidized beds, Venturi aspirators and the Wright dust feed, were tested; however, none were able to produce nanoparticle aerosols which satisfy all criteria (5). A whole-body nanoparticle aerosol inhalation exposure system was fabricated, validated and utilized for nano-TiO2 inhalation toxicology studies. Critical components: 1) novel nano-TiO2 aerosol generator; 2) 0.5 m(3) whole-body inhalation exposure chamber; and 3) monitor and control system. Nano-TiO2 aerosols generated from bulk dry nano-TiO2 powders (primary diameter of 21 nm, bulk density of 3.8 g/cm(3)) were delivered into the exposure chamber at a flow rate of 90 LPM (10.8 air changes/hr). Particle size distribution and mass concentration profiles were measured continuously with a scanning mobility particle sizer (SMPS), and an electric low pressure impactor (ELPI). The aerosol mass concentration (C) was verified gravimetrically (mg/m(3)). The mass (M) of the collected particles was determined as M = (Mpost-Mpre), where Mpre and Mpost are masses of the filter before and after sampling (mg). The mass concentration was calculated as C = M

  13. Whole-Body Nanoparticle Aerosol Inhalation Exposures

    PubMed Central

    Yi, Jinghai; Chen, Bean T.; Schwegler-Berry, Diane; Frazer, Dave; Castranova, Vince; McBride, Carroll; Knuckles, Travis L.; Stapleton, Phoebe A.; Minarchick, Valerie C.; Nurkiewicz, Timothy R.

    2013-01-01

    Inhalation is the most likely exposure route for individuals working with aerosolizable engineered nano-materials (ENM). To properly perform nanoparticle inhalation toxicology studies, the aerosols in a chamber housing the experimental animals must have: 1) a steady concentration maintained at a desired level for the entire exposure period; 2) a homogenous composition free of contaminants; and 3) a stable size distribution with a geometric mean diameter < 200 nm and a geometric standard deviation σg < 2.5 5. The generation of aerosols containing nanoparticles is quite challenging because nanoparticles easily agglomerate. This is largely due to very strong inter-particle forces and the formation of large fractal structures in tens or hundreds of microns in size 6, which are difficult to be broken up. Several common aerosol generators, including nebulizers, fluidized beds, Venturi aspirators and the Wright dust feed, were tested; however, none were able to produce nanoparticle aerosols which satisfy all criteria 5. A whole-body nanoparticle aerosol inhalation exposure system was fabricated, validated and utilized for nano-TiO2 inhalation toxicology studies. Critical components: 1) novel nano-TiO2 aerosol generator; 2) 0.5 m3 whole-body inhalation exposure chamber; and 3) monitor and control system. Nano-TiO2 aerosols generated from bulk dry nano-TiO2 powders (primary diameter of 21 nm, bulk density of 3.8 g/cm3) were delivered into the exposure chamber at a flow rate of 90 LPM (10.8 air changes/hr). Particle size distribution and mass concentration profiles were measured continuously with a scanning mobility particle sizer (SMPS), and an electric low pressure impactor (ELPI). The aerosol mass concentration (C) was verified gravimetrically (mg/m3). The mass (M) of the collected particles was determined as M = (Mpost-Mpre), where Mpreand Mpost are masses of the filter before and after sampling (mg). The mass concentration was calculated as C = M/(Q*t), where Q is

  14. Performance evaluation of selected n95 respirators and surgical masks when challenged with aerosolized endospores and inert particles.

    PubMed

    Davidson, Craig S; Green, Christopher F; Gibbs, Shawn G; Schmid, Kendra K; Panlilio, Adelisa L; Jensen, Paul A; Scarpino, Pasquale V

    2013-01-01

    The objective of this study was to assess how the relative efficiency of N95 respirators and surgical masks might vary with different challenge aerosols, utilizing a standardized manikin head form as a surrogate to human participation. A Collision nebulizer aerosolized B. anthracis Sterne strain endospores and polystyrene latex (PSL) particles to evaluate 11 models of N95 respirators and surgical masks. An automated breathing simulator, calibrated to normal tidal volume and active breathing rate, mimicked human respiration. A manikin head form with N95 respirators or surgical masks, and manikin head form without N95 respirators or surgical masks were placed in the bioaerosol chamber. An AGI-30 sampler filled with phosphate buffered water was fitted behind the mouth of each manikin head form to collect endospore bioaerosol samples. PSL aerosols concentrations were quantified by an ARTI Hand Held Particle Counter. Geometric Mean (GM) relative efficiency of N95 respirators and surgical masks challenged with endospore bioaerosol ranged from 34-65%. In PSL aerosol experiments, GM relative efficiency ranged from 35-64% for 1.3 μm particles. GM filtration efficiency of all N95 and surgical N95 respirators filter media evaluated was ≥99% when challenged with particles ≥0.1 μm. GM filtration efficiency of surgical mask filter media ranged from 70-83% with particles ≥0.1 μm and 74-92% with 1.3 μm PSL particles. Relative efficiencies of N95 respirators and surgical masks challenged with aerosolized B. anthracis endospores and PSL were similar. Relative efficiency was similar between N95 respirators and surgical masks on a manikin head form despite clear differences in filtration efficiency. This study further highlights the importance of face seal leakage in the respiratory protection provided by N95 respirators, and demonstrates it on a human surrogate. PMID:23915331

  15. Simultaneous determination of phenolic compounds in Equisetum palustre L. by ultra high performance liquid chromatography with tandem mass spectrometry combined with matrix solid-phase dispersion extraction.

    PubMed

    Wei, Zuofu; Pan, Youzhi; Li, Lu; Huang, Yuyang; Qi, Xiaolin; Luo, Meng; Zu, Yuangang; Fu, Yujie

    2014-11-01

    A method based on matrix solid-phase dispersion extraction followed by ultra high performance liquid chromatography with tandem mass spectrometry is presented for the extraction and determination of phenolic compounds in Equisetum palustre. This method combines the high efficiency of matrix solid-phase dispersion extraction and the rapidity, sensitivity, and accuracy of ultra high performance liquid chromatography with tandem mass spectrometry. The influential parameters of the matrix solid-phase dispersion extraction were investigated and optimized. The optimized conditions were as follows: silica gel was selected as dispersing sorbent, the ratio of silica gel to sample was selected to be 2:1 (400/200 mg), and 8 mL of 80% methanol was used as elution solvent. Furthermore, a fast and sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed for the determination of nine phenolic compounds in E. palustre. This method was carried out within <6 min, and exhibited satisfactory linearity, precision, and recovery. Compared with ultrasound-assisted extraction, the proposed matrix solid-phase dispersion procedure possessed higher extraction efficiency, and was more convenient and time saving with reduced requirements on sample and solvent amounts. All these results suggest that the developed method represents an excellent alternative for the extraction and determination of active components in plant matrices. PMID:25132205

  16. Potential Annealing Treatments for Tailoring the Starting Microstructure of Low-Enriched U-Mo Dispersion Fuels to Optimize Performance During Irradiation

    SciTech Connect

    Dennis D. Keiser, Jr.; Jan-Fong Jue; Nicolas E. Woolstenhulme; Ashley Ewh

    2011-12-01

    Low-enriched uranium-molybdenum alloy particles dispersed in aluminum alloy (e.g., dispersion fuels) are being developed for application in research and test reactors. To achieve the best performance of these fuels during irradiation, optimization of the starting microstructure may be required by utilizing a heat treatment that results in the formation of uniform, Si-rich interaction layers between the U-Mo particles and Al-Si matrix. These layers behave in a stable manner under certain irradiation conditions. To identify the optimum heat treatment for producing these kinds of layers in a dispersion fuel plate, a systematic annealing study has been performed using actual dispersion fuel samples, which were fabricated at relatively low temperatures to limit the growth of any interaction layers in the samples prior to controlled heat treatment. These samples had different Al matrices with varying Si contents and were annealed between 450 and 525 C for up to 4 hours. The samples were then characterized using scanning electron microscopy (SEM) to examine the thickness, composition, and uniformity of the interaction layers. Image analysis was performed to quantify various attributes of the dispersion fuel microstructures that related to the development of the interaction layers. The most uniform layers were observed to form in fuel samples that had an Al matrix with at least 4 wt% Si and a heat treatment temperature of at least 475 C.

  17. Influence of polymer molecular weight on in vitro dissolution behavior and in vivo performance of celecoxib:PVP amorphous solid dispersions.

    PubMed

    Knopp, Matthias Manne; Nguyen, Julia Hoang; Becker, Christian; Francke, Nadine Monika; Jørgensen, Erling B; Holm, Per; Holm, René; Mu, Huiling; Rades, Thomas; Langguth, Peter

    2016-04-01

    In this study, the influence of the molecular weight of polyvinylpyrrolidone (PVP) on the non-sink in vitro dissolution and in vivo performance of celecoxib (CCX):PVP amorphous solid dispersions were investigated. The dissolution rate of CCX from the amorphous solid dispersions increased with decreasing PVP molecular weight and crystallization inhibition was increased with increasing molecular weight of PVP, but reached a maximum for PVP K30. This suggested that the crystallization inhibition was not proportional with molecular weight of the polymer, but rather there was an optimal molecular weight where the crystallization inhibition was strongest. Consistent with the findings from the non-sink in vitro dissolution tests, the amorphous solid dispersions with the highest molecular weight PVPs (K30 and K60) resulted in significantly higher in vivo bioavailability (AUC0-24h) compared with pure amorphous and crystalline CCX. A linear relationship between the in vitro and in vivo parameter AUC0-24h indicated that the simple non-sink in vitro dissolution method used in this study could be used to predict the in vivo performance of amorphous solid dispersion with good precision, which enabled a ranking between the different formulations. In conclusion, the findings of this study demonstrated that the in vitro and in vivo performance of CCX:PVP amorphous solid dispersions were significantly controlled by the molecular weight of the polymer. PMID:26899127

  18. Atmospheric aerosols: Their Optical Properties and Effects (supplement)

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A digest of technical papers is presented. Topics include aerosol size distribution from spectral attenuation with scattering measurements; comparison of extinction and backscattering coefficients for measured and analytic stratospheric aerosol size distributions; using hybrid methods to solve problems in radiative transfer and in multiple scattering; blue moon phenomena; absorption refractive index of aerosols in the Denver pollution cloud; a two dimensional stratospheric model of the dispersion of aerosols from the Fuego volcanic eruption; the variation of the aerosol volume to light scattering coefficient; spectrophone in situ measurements of the absorption of visible light by aerosols; a reassessment of the Krakatoa volcanic turbidity, and multiple scattering in the sky radiance.

  19. The performance and the characterization of laser ablation aerosol particle time-of-flight mass spectrometry (LAAP-ToF-MS)

    NASA Astrophysics Data System (ADS)

    Gemayel, Rachel; Hellebust, Stig; Temime-Roussel, Brice; Hayeck, Nathalie; Van Elteren, Johannes T.; Wortham, Henri; Gligorovski, Sasho

    2016-05-01

    Hyphenated laser ablation-mass spectrometry instruments have been recognized as useful analytical tools for the detection and chemical characterization of aerosol particles. Here we describe the performances of a laser ablation aerosol particle time-of-flight mass spectrometer (LAAP-ToF-MS) which was designed for aerodynamic particle sizing using two 405 nm scattering lasers and characterization of the chemical composition of single aerosol particle via ablation/ionization by a 193 nm excimer laser and detection in a bipolar time-of-flight mass spectrometer with a mass resolving power of m/Δm > 600.

    We describe a laboratory based optimization strategy for the development of an analytical methodology for characterization of atmospheric particles using the LAAP-ToF-MS instrument in combination with a particle generator, a differential mobility analyzer and an optical particle counter. We investigated the influence of particle number concentration, particle size and particle composition on the detection efficiency. The detection efficiency is a product of the scattering efficiency of the laser diodes and the ionization efficiency or hit rate of the excimer laser. The scattering efficiency was found to vary between 0.6 and 1.9 % with an average of 1.1 %; the relative standard deviation (RSD) was 17.0 %. The hit rate exhibited good repeatability with an average value of 63 % and an RSD of 18 %. In addition to laboratory tests, the LAAP-ToF-MS was used to sample ambient air during a period of 6 days at the campus of Aix-Marseille University, situated in the city center of Marseille, France. The optimized LAAP-ToF-MS methodology enables high temporal resolution measurements of the chemical composition of ambient particles, provides new insights into environmental science, and a new investigative tool for atmospheric chemistry and physics, aerosol science and health impact studies.

  20. A microscale model for air pollutant dispersion simulation in urban areas: Presentation of the model and performance over a single building

    NASA Astrophysics Data System (ADS)

    Zhang, Ning; Du, Yunsong; Miao, Shiguang

    2016-02-01

    A microscale air pollutant dispersion model system is developed for emergency response purposes. The model includes a diagnostic wind field model to simulate the wind field and a random-walk air pollutant dispersion model to simulate the pollutant concentration through consideration of the influence of urban buildings. Numerical experiments are designed to evaluate the model's performance, using CEDVAL (Compilation of Experimental Data for Validation of Microscale Dispersion Models) wind tunnel experiment data, including wind fields and air pollutant dispersion around a single building. The results show that the wind model can reproduce the vortexes triggered by urban buildings and the dispersion model simulates the pollutant concentration around buildings well. Typically, the simulation errors come from the determination of the key zones around a building or building cluster. This model has the potential for multiple applications; for example, the prediction of air pollutant dispersion and the evaluation of environmental impacts in emergency situations; urban planning scenarios; and the assessment of microscale air quality in urban areas.

  1. An investigation into the effect of spray drying temperature and atomizing conditions on miscibility, physical stability, and performance of naproxen-PVP K 25 solid dispersions.

    PubMed

    Paudel, Amrit; Loyson, Yves; Van den Mooter, Guy

    2013-04-01

    The present study investigates the effect of changing spray drying temperature (40°C-120°C) and/or atomizing airflow rate (AR; 5-15 L/min) on the phase structure, physical stability, and performance of spray-dried naproxen-polyvinylpyrrolidone (PVP) K 25 amorphous solid dispersions. The modulated differential scanning calorimetry, attenuated total internal reflectance-Fourier transform infrared, and powder X-ray diffractometry (pXRD) studies revealed that higher inlet temperature (IT) or atomization airflow leads to the formation of amorphous-phase-separated dispersions with higher strongly H-bonded and free PVP fractions, whereas that prepared with the lowest IT was more homogeneous. The dispersion prepared with the lowest atomization AR showed trace crystallinity. Upon exposure to 75% relative humidity (RH) for 3 weeks, the phase-separated dispersions generated by spray drying at higher temperature or higher atomization airflow retained relatively higher amorphous drug fraction compared with those prepared at slow evaporation conditions. The humidity-controlled pXRD analysis at 98% RH showed that the dispersion prepared with highest atomization AR displayed the slowest kinetics of recrystallization. The molecular-level changes occurring during recrystallization at 98% RH was elucidated by spectroscopic monitoring at the same humidity. The rate and extent of the drug dissolution was the highest for dispersions prepared at the highest atomizing AR and the lowest for that prepared with the slowest atomizing condition. PMID:23359268

  2. Matrix solid-phase dispersion extraction and high-performance liquid chromatographic determination of residual sulfonamides in chicken.

    PubMed

    Kishida, K; Furusawa, N

    2001-12-01

    Simultaneous determination of the six sulfonamides (SAs) sulfadiazine, sulfadimidine, sulfamonomethoxine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline in chicken using matrix solid-phase dispersion (MSPD) with neutral aluminium oxide as an MSPD sorbent and high-performance liquid chromatography (HPLC) is presented. In the present MSPD, six SAs could be isolated by only one step, elution with a 70% (v/v) aqueous ethanol solution, without the sorbent conditioning and the sorbent-tissue matrix washing. For the HPLC determination, a LiChrospher 100 RP-8 and a mixture of 1% acetic acid solution (pH 3.0, in water)-acetonitrile-N,N-dimethylformamide (78:22:5, v/v/v) as the mobile phase with a photodiode array detector were used. Average recoveries were greater than 87.6% with relative standard deviations between 0.5 and 8.6%. The total time and amount of solvent required for the analysis of one sample were <1.5 h and <12 ml, respectively. PMID:11765084

  3. A Transition Edge Sensor Microcalorimeter System for the Energy Dispersive Spectroscopy Performed on a Scanning-Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Maehata, K.; Hara, T.; Mitsuda, K.; Hidaka, M.; Tanaka, K.; Yamanaka, Y.

    2015-11-01

    We are conducting the development of a transition edge sensor (TES) microcalorimeter system for energy-dispersive X-ray spectroscopy (EDS), performed using a scanning-transmission electron microscope (STEM). The operating temperature of the TES microcalorimeter was maintained using a compact dry 3 He-4 He dilution refrigerator. This was pre-cooled by a remote helium cooling loop system and a Gifford-McMahon cooler. These conditions allowed for high-resolution STEM imaging to be achieved. A single-pixel TES microcalorimeter with a polycapillary optic was selected to demonstrate the analytical operation of the EDS system in the STEM. For a Ti-It-Pt sample, an X-ray energy resolution of 8.6 eV full-width at half maximum (FWHM) was obtained at Ir M_{α 1} , Pt M_{α 1} , and Ir M_{β } . Using an electron device sample, element distribution maps of Si, Ti, and W were obtained using a Si K_{α 1} X-ray energy resolution of 9.7 eV FWHM.

  4. A Transition Edge Sensor Microcalorimeter System for the Energy Dispersive Spectroscopy Performed on a Scanning-Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Maehata, K.; Hara, T.; Mitsuda, K.; Hidaka, M.; Tanaka, K.; Yamanaka, Y.

    2016-07-01

    We are conducting the development of a transition edge sensor (TES) microcalorimeter system for energy-dispersive X-ray spectroscopy (EDS), performed using a scanning-transmission electron microscope (STEM). The operating temperature of the TES microcalorimeter was maintained using a compact dry 3He-4He dilution refrigerator. This was pre-cooled by a remote helium cooling loop system and a Gifford-McMahon cooler. These conditions allowed for high-resolution STEM imaging to be achieved. A single-pixel TES microcalorimeter with a polycapillary optic was selected to demonstrate the analytical operation of the EDS system in the STEM. For a Ti-It-Pt sample, an X-ray energy resolution of 8.6 eV full-width at half maximum (FWHM) was obtained at Ir M_{α 1}, Pt M_{α 1}, and Ir M_{β }. Using an electron device sample, element distribution maps of Si, Ti, and W were obtained using a Si K_{α 1} X-ray energy resolution of 9.7 eV FWHM.

  5. Studies on effects of feedback delay on the convergence performance of adaptive time-domain equalizers for fiber dispersive channels

    NASA Astrophysics Data System (ADS)

    Guo, Qun; Xu, Bo; Qiu, Kun

    2016-04-01

    Adaptive time-domain equalizer (TDE) is an important module for digital optical coherent receivers. From an implementation perspective, we analyze and compare in detail the effects of error signal feedback delay on the convergence performance of TDE using either least-mean square (LMS) or constant modulus algorithm (CMA). For this purpose, a simplified theoretical model is proposed based on which iterative equations on the mean value and the variance of the tap coefficient are derived with or without error signal feedback delay for both LMS- and CMA-based methods for the first time. The analytical results show that decreased step size has to be used for TDE to converge and a slower convergence speed cannot be avoided as the feedback delay increases. Compared with the data-aided LMS-based method, the CMA-based method has a slower convergence speed and larger variation after convergence. Similar results are confirmed using numerical simulations for fiber dispersive channels. As the step size increases, a feedback delay of 20 clock cycles might cause the TDE to diverge. Compared with the CMA-based method, the LMS-based method has a higher tolerance on the feedback delay and allows a larger step size for a faster convergence speed.

  6. Relative neutronic performance of proposed high-density dispersion fuels in water-moderated and D{sub 2}O-reflected research reactors

    SciTech Connect

    Bretscher, M.M.; Matos, J.E.; Snelgrove, J.L.

    1996-12-01

    This paper provides an overview of the neutronic performance of an idealized research reactor using several high density LEU fuels that are being developed by the RERTR program. High-density LEU dispersion fuels are needed for new and existing high-performance research reactors and to extend the lifetime of fuel elements in other research reactors. This paper discusses the anticipated neutronic behavior of proposed advanced fuels containing dispersions of U{sub 3}Si{sub 2}, UN, U{sub 2}Mo and several uranium alloys with Mo, or Zr and Nb. These advanced fuels are ranked based on the results of equilibrium depletion calculations for a simplified reactor model having a small H{sub 2}O-cooled core and a D{sub 2}O reflector. Plans have been developed to fabricate and irradiate several uranium alloy dispersion fuels in order to test their stability and compatibility with the matrix material and to establish practical loading limits.

  7. SMED - Sulphur MEditerranean Dispersion

    NASA Astrophysics Data System (ADS)

    Salerno, Giuseppe G.; Sellitto, Pasquale; Corradini, Stefano; Di Sarra, Alcide Giorgio; Merucci, Luca; Caltabiano, Tommaso; La Spina, Alessandro

    2016-04-01

    Emissions of volcanic gases and particles can have profound impacts on terrestrial environment, atmospheric composition, climate forcing, and then on human health at various temporal and spatial scales. Volcanic emissions have been identified as one of the largest sources of uncertainty in our understanding of recent climate change trends. In particular, a primary role is acted by sulphur dioxide emission due to its conversion to volcanic sulphate aerosol via atmospheric oxidation. Aerosols may play a key role in the radiative budget and then in photochemistry and tropospheric composition. Mt. Etna is one of the most prodigious and persistent emitters of gasses and particles on Earth, accounting for about 10% of global average volcanic emission of CO2 and SO2. Its sulphur emissions stand for 0.7 × 106 t S/yr9 and then about 10 times bigger than anthropogenic sulphur emissions in the Mediterranean area. Centrepiece of the SMED project is to advance the understanding of volcanogenic sulphur dioxide and sulphate aerosol particles dispersion and radiative impact on the downwind Mediterranean region by an integrated approach between ground- and space-based observations and modelling. Research is addressed by exploring the potential relationship between proximal SO2 flux and aerosol measured remotely in the volcanic plume of Mt. Etna between 2000 and 2014 and distal aerosol ground-based measurements in Lampedusa, Greece, and Malta from AERONET network. Ground data are combined with satellite multispectral polar and geostationary imagers able to detect and retrieve volcanic ash and SO2. The high repetition time of SEVIRI (15 minutes) will ensure the potential opportunity to follow the entire evolution of the volcanic cloud, while, the higher spatial resolution of MODIS (1x1 km2), are exploited for investigating the probability to retrieve volcanic SO2 abundances from passive degassing. Ground and space observations are complemented with atmospheric Lagrangian model

  8. An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

    NASA Astrophysics Data System (ADS)

    Rumsey, I. C.; Cowen, K.; Kelly, T.; Hanft, E.; Mishoe, K.; Rogers, C.; Proost, R.; Lear, G.; Frelink, T.; Walker, J. T.

    2011-12-01

    Ambient air monitoring as part of the U.S. EPA's Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The U.S. EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to examine ecosystem exposure to nitrogen and sulfur compounds at higher time resolution and with greater accuracy than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at hourly temporal resolution. The performance of the MARGA was assessed under the U.S. EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, NC from September 8th-October 8th, 2010. Precision of the MARGA was evaluated by comparing duplicate units and accuracy was evaluated by comparing duplicate MARGAs to duplicate reference denuder/filter packs. The MARGA utilizes a Wet Rotating Denuder (WRD) to collect gases, while aerosols are collected by a Steam Jet Aerosol Collector (SJAC). Both the WRD and the SJAC produce aqueous sample streams, which are analyzed by online ion chromatography for anions and cations. The reference denuder/filter pack consisted of sodium carbonate (Na2CO3) and phosphorous acid (H3PO3) coated denuders followed by a Teflon filter, a nylon filter, and a citric acid coated cellulose filter. The assessment of the MARGA units focused on gaseous SO2, HNO3 and NH3 and aerosol SO4-, NO3- and NH4+. To evaluate accuracy, hourly MARGA concentrations were averaged over 12 hours to match with 12-hour integrated concentrations from the reference system. The concentrations were compared using linear regression with performance goals of slope between 0.8-1.2 and y-intercept between -10 ppb and 10 ppb. Accuracy was further quantified as the median absolute relative percent difference (MARPD) between 12-hour MARGA and reference concentrations, with a performance goal of ≤ 40%. The precision of

  9. Visible-light-driven photocatalysts Ag/AgCl dispersed on mesoporous Al2O3 with enhanced photocatalytic performance.

    PubMed

    Feng, Zhouzhou; Yu, Jiajie; Sun, Dongping; Wang, Tianhe

    2016-10-15

    In this paper, Ag/AgCl and Ag/AgCl/Al2O3 photocatalysts were synthesized via a precipitation reaction between NaCl and CH3COOAg or Ag(NH3)2NO3, wherein Ag/AgCl was immobilized into mesoporous Al2O3 medium. The Ag/AgCl-based nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra, and so on. The photocatalysts displayed excellent photocatalytic activity for the degradations of methyl orange (MO) and methylene blue (MB) pollutants under visible light irradiation. The Ag/AgCl(CH3COOAg)/Al2O3 sample exhibited the best photocatalytic performance, degrading 99% MO after 9min of irradiation, which was 1.1 times, 1.22 times and 1.65 times higher than that of Ag/AgCl(Ag(NH3)2NO3)/Al2O3, Ag/AgCl(CH3COOAg) and Ag/AgCl(Ag(NH3)2NO3) photocatalyst, respectively. Meanwhile, Ag/AgCl(CH3COOAg)/Al2O3 also showed excellent capability of MB degradation. Compared to the data reported for Ag/AgCl/TiO2, the Ag/AgCl/Al2O3 prepared in this work exhibited a good performance for the degradation of methyl orange (MO). The results suggest that the dispersion of Ag/AgCl on mesoporous Al2O3 strongly affected their photocatalytic activities. O2(-), OH radicals and Cl(0) atoms are main active species during photocatalysis. PMID:27442145

  10. Oil dispersants

    SciTech Connect

    Flaherty, L.M.

    1989-01-01

    This book contains papers presented at a symposium of the American Society for Testing and Materials. The topics covered include: The effect of elastomers on the efficiency of oil spill dispersants; planning for dispersant use; field experience with dispersants for oil spills on land; and measurements on natural dispersion.

  11. Performance evaluation of the pilot-scale, double-shell tank ventilation system using simulated aerosol streams

    SciTech Connect

    Brouns, T.M.; Peterson, M.E.

    1989-12-01

    Radioactive waste slurries are currently being stored in underground tanks on the Hanford Site. The slurries that are being stored in the double-shell tanks (DSTs) are various mixtures of radioactive solids, liquids, and aqueous wastes. The tanks must be maintained at a negative pressure relative to atmospheric pressure to safeguard against pressurization and the subsequent leakage of entrained radioactive aerosols to the environment. A ventilation system must be capable of withdrawing the total volume of off gas generated from the tanks while maintaining the tanks at a negative pressure. Westinghouse Hanford Company (WHC) has identified a need to improve the efficiency of the ventilation system being used on the tank farms to meet the more restrictive release limits for radioactive isotopes. Kaiser Engineers Hanford Company (KEH) has been contracted by WHC to design the new ventilation system for the existing tank farms. WHC contracted the Pacific Northwest Laboratory (PNL) to fabricate and test the prototypic pilot-scale design prior to finalizing the design of the ventilation system. The PNL has conducted tests to determine (1) the effectiveness of the system for removal of vapors condensable at 35{degrees}F, (2) the effectiveness for removal of soluble and insoluble aerosols, and (3) the life span of the mist eliminators to be used in the new system. The results of extensive testing of the pilot-scale system with condensables and both soluble and insoluble aerosols are presented in this report. 7 refs., 25 figs., 8 tabs.

  12. TiO2/CdS porous hollow microspheres rapidly synthesized by salt-assistant aerosol decomposition method for excellent photocatalytic hydrogen evolution performance.

    PubMed

    Huang, Yu; Chen, Jun; Zou, Wei; Zhang, Linxing; Hu, Lei; He, Min; Gu, Lin; Deng, Jinxia; Xing, Xianran

    2016-01-21

    TiO2/CdS porous hollow microspheres have been one-pot rapidly synthesized by a salt-assisted aerosol decomposition method, and exhibit an excellent photocatalytic activity of 996 μmol h(-1) (50 mg photocatalysts with loading Ru co-catalyst) for hydrogen evolution from aqueous solutions containing sacrificial reagents (SO3(2-) and S(2-)) under visible light (λ ≥ 420 nm). Its high photocatalytic performance is attributed to the surface morphology, crystallinity and heterostructures. The present facile method can be extended to fabricate other heterostructures consisting of oxides or sulfides. PMID:26661031

  13. Four dimensional variational assimilation of in-situ and remote-sensing aerosol data

    NASA Astrophysics Data System (ADS)

    Nieradzik, L. P.; Elbern, H.

    2012-04-01

    Aerosols play an increasingly important role in atmospheric modelling. They have a strong influence on the radiative transfer balance and a significant impact on human health. Their origin is various and so are its effects. Most of the measurement sites in Europe account for an integrated aerosol load PMx (Particulate Matter of less than x μm in diameter) which does not give any qualitative information on the composition of the aerosol. Since very different constituents contribute to PMx, like e.g. mineral dust derived from desert storms or sea salt, it is necessary to make aerosol forecasts not only of load, but also type resolved. The method of four dimensional variational data assimilation (4Dvar) is a widely known technique to enhance forecast skills of CTMs (Chemistry-Transport-Models) by ingesting in-situ and, especially, remote-sensing measurements. The EURAD-IM (EURopean Air pollution Dispersion - Inverse Model), containing a full adjoint gas-phase model, has been expanded with an adjoint of the MADE (Modal Aerosol Dynamics model for Europe) to optimise initial and boundary values for aerosols using 4Dvar. A forward and an adjoint radiative transfer model is driven by the EURAD-IM as mapping between BLAOT (Boundary Layer Aerosol Optical Thickness) and internal aerosol species. Furthermore, its condensation scheme has been bypassed by an HDMR (High-Dimensional-Model-Representation) to ensure differentiability. In this study both in-situ measured PMx as well as satellite retrieved aerosol optical thicknesses have been assimilated and the effect on forecast performance has been investigated. The source of BLAOT is the aerosol retrieval system SYNAER (SYNergetic AErosol Retrieval) from DLR-DFD that retrieves AOT by making use of both AATSR/SCIAMACHY and AVHRR/GOME-2 data respectively. Its strengths are a large spatial coverage, near real-time availability, and the classification of five intrinsic aerosol species, namely water-solubles, water-insolubles, soot

  14. Graphical aerosol classification method using aerosol relative optical depth

    NASA Astrophysics Data System (ADS)

    Chen, Qi-Xiang; Yuan, Yuan; Shuai, Yong; Tan, He-Ping

    2016-06-01

    A simple graphical method is presented to classify aerosol types based on a combination of aerosol optical thickness (AOT) and aerosol relative optical thickness (AROT). Six aerosol types, including maritime (MA), desert dust (DD), continental (CO), sub-continental (SC), urban industry (UI) and biomass burning (BB), are discriminated in a two dimensional space of AOT440 and AROT1020/440. Numerical calculations are performed using MIE theory based on a multi log-normal particle size distribution, and the AROT ranges for each aerosol type are determined. More than 5 years of daily observations from 8 representative aerosol sites are applied to the method to confirm spatial applicability. Finally, 3 individual cases are analyzed according to their specific aerosol status. The outcomes indicate that the new graphical method coordinates well with regional characteristics and is also able to distinguish aerosol variations in individual situations. This technique demonstrates a novel way to estimate different aerosol types and provide information on radiative forcing calculations and satellite data corrections.

  15. A laser analyzer of aerosol dispersion

    NASA Astrophysics Data System (ADS)

    Kairo, V. S.; Smirnov, V. V.

    1980-10-01

    A small He-Ne laser, wide-angle reflecting optics, an electrostatic diluent, and a graduated measuring device provided a wide range of particle sizing (0.2 to 20 microns) at concentrations ranging from 0.01 to one million particles/cu cm. The device was calibrated by measuring particles of polystyrene, a melamine-formaldehyde resin, aluminum, magnesium, willow seeds, and club moss.

  16. Investigations on particle surface characteristics vs. dispersion behaviour of L-leucine coated carrier-free inhalable powders.

    PubMed

    Raula, Janne; Thielmann, Frank; Naderi, Majid; Lehto, Vesa-Pekka; Kauppinen, Esko I

    2010-01-29

    Aerosol microparticles of salbutamol sulphate are gas-phase coated with an amino acid L-leucine. Depending of the saturated state of L-leucine, the coating is formed by the surface diffusion of L-leucine molecules within a droplet or by the physical vapour deposition (PVD) of L-leucine or by the combination thereof. The PVD coated particles showed excellent aerosolization characteristics in a carrier-free powder delivery from an inhaler. The aerosolization of the fine powders is compared with surface energy parameters analysed by inverse gas chromatography (IGC). The dispersion testing is conducted by a Inhalation Simulator using a fast inhalation profile with inhalation flow rate of 67 l min(-1). It is found that the powder emission is affected by the morphology, surface roughness (asperity size and density) of the particles and acidity of particle surface. The latter affects the dispersion and dose repeatability of fine powder in a case if L-leucine content is high enough. However, there is no direct correlation between dispersive surface energies and aerosolization performances of the powders. Crucial factors for the improved aerosolization rely weakly on surface acid-base properties but strongly on particle morphology and fine-scale surface roughness. PMID:19879344

  17. Growth and immune system performance to assess the effect of dispersed oil on juvenile sea bass (Dicentrarchus labrax).

    PubMed

    Dussauze, Matthieu; Danion, Morgane; Floch, Stéphane Le; Lemaire, Philippe; Theron, Michaël; Pichavant-Rafini, Karine

    2015-10-01

    The potential impact of chemically and mechanically dispersed oil was assessed in a model fish of European coastal waters, the sea bass Dicentrarchus labrax. Juvenile sea bass were exposed for 48h to dispersed oil (mechanically and chemically) or dispersants alone. The impact of these exposure conditions was assessed using growth and immunity. The increase observed in polycyclic aromatic hydrocarbon metabolites in bile indicated oil contamination in the fish exposed to chemical and mechanical dispersion of oil without any significant difference between these two groups. After 28 days of exposure, no significant differences were observed in specific growth rate,apparent food conversion efficiency and daily feeding). Following the oil exposure, fish immunity was assessed by a challenge with Viral Nervous Necrosis Virus (VNNV). Fish mortality was observed over a 42 day period. After 12 days post-infection, cumulative mortality was significantly different between the control group (16% p≤0.05) and the group exposed to chemical dispersion of oil (30% p≤0.05). However, at the end of the experiment, no significant difference was recorded in cumulative mortality or in VNNV antibodies secreted in fish in responses to the treatments. These data suggested that in our experimental condition, following the oil exposure, sea bass growth was not affected whereas an impact on immunity was observed during the first days. However, this effect on the immune system did not persist over time. PMID:26092553

  18. Porous spherical carbon/sulfur nanocomposites by aerosol-assisted synthesis: the effect of pore structure and morphology on their electrochemical performance as lithium/sulfur battery cathodes.

    PubMed

    Sohn, Hiesang; Gordin, Mikhail L; Xu, Terrence; Chen, Shuru; Lv, Dongping; Song, Jiangxuan; Manivannan, Ayyakkannu; Wang, Donghai

    2014-05-28

    Porous spherical carbons (PSCs) with tunable pore structure (pore volume, pore size, and surface area) were prepared by an aerosol-assisted process. PSC/sulfur composites (PSC/S, S: ca.59 wt %) were then made and characterized as cathodes in lithium/sulfur batteries. The relationships between the electrochemical performance of PSC/S composites and their pore structure and particle morphology were systematically investigated. PSC/S composite cathodes with large pore volume (>2.81 cm(3)/g) and pore size (>5.10 nm) were found to exhibit superior electrochemical performance, likely due to better mass transport in the cathode. In addition, compared with irregularly shaped carbon/sulfur composite, the spherical shaped PSC/S composite showed better performance due to better electrical contact among the particles. PMID:24758613

  19. The effect of excipients on the stability and aerosol performance of salmon calcitonin dry powder inhalers prepared via the spray freeze drying process.

    PubMed

    Poursina, Narges; Vatanara, Alireza; Rouini, Mohammad Reza; Gilani, Kambiz; Najafabadi, Abdolhossein Rouholamini

    2016-06-01

    Spray freeze drying was developed to produce dry powders suitable for applications such as inhalation delivery. In the current study, the spray freeze drying technique was employed to produce inhalable salmon calcitonin microparticles. Effects of the carrier type, concentration of hydroxyl propyl-β-cyclodextrin and the presence of Tween 80 on the chemical and structural stability, as well as on the aerosol performance of the particles were investigated. The results indicated that hydroxyl propyl-β-cyclodextrin had the most important effect on the chemical stability of the powder and strongly increased its stability by increasing its concentration in the formulation. Chemically stable formulations (over 90 % recovery) were selected for further examinations. Fluorescence spectroscopy and circular dichroism suggested that the formulations were structurally stable. Aerosol performance showed that the Tween-free powders produced higher fine particle fraction values than the formulations containing Tween (53.7 vs. 41.92 % for trehalose content and 52.85 vs. 43.06 % for maltose content). PMID:27279064

  20. Global Aerosols

    Atmospheric Science Data Center

    2013-04-19

    ... sizes and from multiple sources, including biomass burning, mineral dust, sea salt and regional industrial pollution. A color scale is ... desert source region. Deserts are the main sources of mineral dust, and MISR obtains aerosol optical depth at visible wavelengths ...

  1. An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

    NASA Astrophysics Data System (ADS)

    Rumsey, I. C.; Cowen, K. A.; Walker, J. T.; Kelly, T. J.; Hanft, E. A.; Mishoe, K.; Rogers, C.; Proost, R.; Beachley, G. M.; Lear, G.; Frelink, T.; Otjes, R. P.

    2014-06-01

    Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at an hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina, from 8 September to 8 October 2010 and focused on gaseous SO2, HNO3, and NH3 and aerosol SO42-, NO3-, and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of ≤ 25%. The accuracy of the MARGA was evaluated by calculating the MARPD for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤ 40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42-, and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3- could not be evaluated due to the different sampling efficiency of coarse NO3- by the MUs and the filter pack. Estimates of "fine" NO3- were calculated for the MUs and the filter pack

  2. Simultaneous determination of 17 disperse dyes in textile by ultra-high performance supercritical fluid chromatography combined with tandem mass spectrometry.

    PubMed

    Zhou, Ying; Du, Zhenxia; Zhang, Yun

    2014-09-01

    A simple, highly sensitive and fast procedure for the control of 17 allergenic and prohibited disperse dyes in textile products was optimized. The method was based on ultrasound assisted extraction of textile samples with 10 mL of methanol under controlled conditions (30 min, 70°C). The extracts were analyzed by the ultra-high performance supercritical fluid chromatography (UHPSFC) system coupled with triple quadrupole tandem mass spectrometry (MS/MS). Four stationary phases (BEH, BEH 2-ethyl-pyridine, HSS C18 SB and CSH fluorophenyl) were screened as well as analytical conditions (modifier percentage, backpressure and column temperature) were investigated to improve the separation. All 17 disperse dyes were simultaneously separated and determined by UHPSFC-MS/MS in 5 min. The dyes were monitored via the ESI(+) ionization method and quantified by 3-channel multiple reaction monitoring (MRM). The calibrations were performed and good linear relationship (R≥0.99) was observed within the concentration range of 2-50 μg mL(-1). Satisfactory recoveries (70.55-103.03%) of all the disperse dyes spiked with standards at different levels were demonstrated. This is the first report on the simultaneous analysis of disperse dyes using UHPSFC-MS/MS. PMID:24913864

  3. Generation of a monodispersed aerosol

    NASA Technical Reports Server (NTRS)

    Schenck, H.; Mikasa, M.; Devicariis, R.

    1974-01-01

    The identity and laboratory test methods for the generation of a monodispersed aerosol are reported on, and are subjected to the following constraints and parameters; (1) size distribution; (2) specific gravity; (3) scattering properties; (4) costs; (5) production. The procedure called for the collection of information from the literature, commercial available products, and experts working in the field. The following topics were investigated: (1) aerosols; (2) air pollution -- analysis; (3) atomizers; (4) dispersion; (5) particles -- optics, size analysis; (6) smoke -- generators, density measurements; (7) sprays; (8) wind tunnels -- visualization.

  4. CMAQ model performance enhanced when in-cloud secondary organic aerosol is included: comparisons of organic carbon predictions with measurements.

    PubMed

    Carlton, Annmarie G; Turpin, Barbara I; Altieri, Katye E; Seitzinger, Sybil P; Mathur, Rohit; Roselle, Shawn J; Weber, Rodney J

    2008-12-01

    Mounting evidence suggests that low-volatility (particle-phase) organic compounds form in the atmosphere through aqueous phase reactions in clouds and aerosols. Although some models have begun including secondary organic aerosol (SOA) formation through cloud processing, validation studies that compare predictions and measurements are needed. In this work, agreement between modeled organic carbon (OC) and aircraft measurements of water soluble OC improved for all 5 of the compared ICARTT NOAA-P3 flights during August when an in-cloud SOA (SOAcld) formation mechanism was added to CMAQ (a regional-scale atmospheric model). The improvement was most dramatic for the August 14th flight, a flight designed specifically to investigate clouds. During this flight the normalized mean bias for layer-averaged OC was reduced from -64 to -15% and correlation (r) improved from 0.5 to 0.6. Underpredictions of OC aloft by atmospheric models may be explained, in part, by this formation mechanism (SOAcld). OC formation aloft contributes to long-range pollution transport and has implications to radiative forcing, regional air quality and climate. PMID:19192800

  5. Evaluation of the performance of four chemical transport models in predicting the aerosol chemical composition in Europe in 2005

    NASA Astrophysics Data System (ADS)

    Prank, Marje; Sofiev, Mikhail; Tsyro, Svetlana; Hendriks, Carlijn; Semeena, Valiyaveetil; Vazhappilly Francis, Xavier; Butler, Tim; Denier van der Gon, Hugo; Friedrich, Rainer; Hendricks, Johannes; Kong, Xin; Lawrence, Mark; Righi, Mattia; Samaras, Zissis; Sausen, Robert; Kukkonen, Jaakko; Sokhi, Ranjeet

    2016-05-01

    Four regional chemistry transport models were applied to simulate the concentration and composition of particulate matter (PM) in Europe for 2005 with horizontal resolution ~ 20 km. The modelled concentrations were compared with the measurements of PM chemical composition by the European Monitoring and Evaluation Programme (EMEP) monitoring network. All models systematically underestimated PM10 and PM2.5 by 10-60 %, depending on the model and the season of the year, when the calculated dry PM mass was compared with the measurements. The average water content at laboratory conditions was estimated between 5 and 20 % for PM2.5 and between 10 and 25 % for PM10. For majority of the PM chemical components, the relative underestimation was smaller than it was for total PM, exceptions being the carbonaceous particles and mineral dust. Some species, such as sea salt and NO3-, were overpredicted by the models. There were notable differences between the models' predictions of the seasonal variations of PM, mainly attributable to different treatments or omission of some source categories and aerosol processes. Benzo(a)pyrene concentrations were overestimated by all the models over the whole year. The study stresses the importance of improving the models' skill in simulating mineral dust and carbonaceous compounds, necessity for high-quality emissions from wildland fires, as well as the need for an explicit consideration of aerosol water content in model-measurement comparison.

  6. [Rapid screening and identification of 22 allergenic disperse dyes in ecological textiles by high performance liquid chromatography-linear ion trap/orbitrap mass spectrometry].

    PubMed

    Niu, Zengyuan; Luo, Xin; Ye, Xiwen; Xiu, Xiaoli; Zhang, Li; Wang, Xin; Chen, Jing

    2015-10-01

    A rapid screening method based on high performance liquid chromatography-linear ion trap/orbitrap high-resolution mass spectrometry (HPLC-LTQ/Orbitrap MS) for 22 disperse dyes in ecological textiles has been established. The target compounds were extracted by pyridine/water (1:1, v/v) by shaking extraction in 90 degrees C water bath. The extracts were then separated by a CAPCELL PAK C18 column (100 mm x 2.0 mm, 5 μm) using gradient elution with acetonitrile-5 mmol/L ammonium acetate containing 0.01% (v/v) formic acid as mobile phases, and finally analyzed by HPLC-LTQ/Orbitrap in positive and negative ESI modes. The retention time and accurate mass of parent ion were used for fast screening of 22 disperse dyes, while the confirmatory analysis was obtained by fragments generated by collision-induced dissociation (CID) MS/MS. Target analysis exhibited high mass accuracy (< 5 x 10(-6)). Each target showed a good linearity in its own concentration range and the correlation coefficient was higher than 0.99. The LOQs were 0.125-2.5 mg/kg. Except for Disperse Yellow 49, the average recoveries of most disperse dyes at three spiked levels were 65%-120%, and the relative standard deviations (n = 6) were less than 15%. The method was applied for screening 40 different kinds of textiles, and Disperse Orange 37/76 was detected in one of them. With high selectivity and strong anti-jamming ability, this method is simple, rapid, accurate, and it can be used for the inspection of disperse dyes in textiles. PMID:26930969

  7. AERMOD: A DISPERSION MODEL FOR INDUSTRIAL SOURCE APPLICATIONS PART II: MODEL PERFORMANCE AGAINST 17 FIELD STUDY DATABASES

    EPA Science Inventory

    The formulations of the AMS/EPA Regulatory Model Improvement Committee's applied air dispersion model (AERMOD) are described. This is the second in a series of three articles. Part I describes the model's methods for characterizing the atmospheric boundary layer and complex ter...

  8. Aerosol physical, chemical and optical properties observed in the ambient atmosphere during haze pollution conditions

    NASA Astrophysics Data System (ADS)

    Li, Zhengqiang; Xie, Yisong; Li, Donghui; Li, Kaitao; Zhang, Ying; Li, Li; Lv, Yang; Qie, Lili; Xu, Hua

    Aerosol’s properties in the ambient atmosphere may differ significantly from sampling results due to containing of abundant water content. We performed sun-sky radiometer measurements in Beijing during 2011 and 2012 winter to obtain distribution of spectral and angular sky radiance. The measurements are then used to retrieve aerosol physical, chemical and optical properties, including single scattering albedo, size distribution, complex refractive indices and aerosol component fractions identified as black carbon, brown carbon, mineral dust, ammonium sulfate-like components and water content inside particle matters. We found that during winter haze condition aerosol is dominated by fine particles with center radius of about 0.2 micron. Fine particles contribute about 93% to total aerosol extinction of solar light, and result in serious decrease of atmospheric visibility during haze condition. The percentage of light absorption of haze aerosol can up to about 10% among its total extinction, much higher than that of unpolluted conditions, that causes significant radiative cooling effects suppressing atmospheric convection and dispersion of pollutants. Moreover, the average water content occupies about one third of the ambient aerosol in volume which suggests the important effect of ambient humidity in the formation of haze pollution.

  9. Formation and deposition of volcanic sulfate aerosols on Mars

    NASA Technical Reports Server (NTRS)

    Settle, M.

    1979-01-01

    The paper considers the formation and deposition of volcanic sulfate aerosols on Mars. The rate limiting step in sulfate aerosol formation on Mars is the gas phase oxidation of SO2 by chemical reactions with O, OH, and HO2; submicron aerosol particles would circuit Mars and then be removed from the atmosphere by gravitational forces, globally dispersed, and deposited over a range of equatorial and mid-latitudes. Volcanic sulfate aerosols on Mars consist of liquid droplets and slurries containing sulfuric acid; aerosol deposition on a global or hemispheric scale could account for the similar concentrations of sulfur within surficial soils at the two Viking lander sites.

  10. Ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction coupled with high performance liquid chromatography for sensitive determination of trace celastrol in urine.

    PubMed

    Sun, Jian-Nan; Shi, Yan-Ping; Chen, Juan

    2011-11-15

    Ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction (UA IL-DLLME) coupled with high-performance liquid chromatography (HPLC) has been developed for the determination of celastrol in human urine samples. In the microextraction procedure, ionic liquid (IL) was used as extraction solvent and dispersed into the aqueous sample solution as fine droplets by means of dispersive solvent and ultrasonication which promoted the analyte to migrate into IL phase more easily. Several important parameters affecting the extraction efficiency were studied and optimized, including the type and volume of extraction solvent and dispersive solvent, sample pH, ultrasonication time, cooling time, centrifugation time and salting-out effect. Under the optimized conditions, 110-fold enrichment factor was obtained and the limit of detection (LOD) was 1.6 μg/L at a signal-to-noise ratio of 3. The calibration curve was linear over the range of 10-1000 μg/L for celastrol in human urine sample, with a correlation coefficient of 0.9980. Intra- and inter-assay precision were 0.43% and 2.78%, respectively. The proposed method was successfully applied to the real human urine samples and good spiked recoveries in the range of 93.2-109.3% were obtained. PMID:21963272

  11. Determination of six pyrethroid insecticides in fruit juice samples using dispersive liquid-liquid microextraction combined with high performance liquid chromatography.

    PubMed

    Boonchiangma, Suthasinee; Ngeontae, Wittaya; Srijaranai, Supalax

    2012-01-15

    Dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography (HPLC) with UV detection was applied for the determination of six pyrethroids (tetramethrin, fenpropathrin, cypermethrin, deltamethrin, fenvalerate and permethrin) in various fruit juices including apple, red grape, orange, kiwi, passion fruit, pomegranate and guava juice. Six pyrethroids were separated within 30 min using a Waters Atlantis T3 column under an isocratic elution of acetonitrile-water (72:28). The parameters affecting extraction efficiency of the DLLME method such as type of disperser and extraction solvent, volume of disperser and extraction solvent and centrifugation time were investigated. Under the optimum conditions, 5.00 mL of sample solution, 300 μL of chloroform as extraction solvent and 1.25 mL of methanol as dispersive solvent gave high enrichment factor in the range of 62-84. Good linearity was obtained from 2 to 1,500 μg/L (r(2)>0.995). The mean recoveries of the pyrethroids evaluated by fortification of real samples were in the range of 84-94%. The limits of detection ranging from 2 to 5 μg/L are sufficient to analyze pyrethroid residues at the maximum residue limits (MRLs) established by the European Union (EU) in fruit juices. The proposed method can be applied to direct determination of pyrethroid residues in fruit juices. PMID:22265489

  12. Numerical study on mixing performance of glass fiber dispersion in a twin-screw extruder with backward-mixing elements

    NASA Astrophysics Data System (ADS)

    Hirata, Kunihiro; Ishida, Hiroshi; Hiragori, Motohiro; Nakayama, Yasuya; Kajiwara, Toshihisa

    2015-05-01

    In the kneading of glass-fiber-reinforced plastics by twin-screw extrusion, the use of a backward-mixing screw (BMS) element for melt mixing has been found to be effective in dispersing glass-fiber bundles. In this study, we use the computational fluid dynamics (CFD) to study the mechanism of dispersion by a BMS element for glass fiber bundles. The result of CFD for a BMS and a forward kneading disk (FKD) reveals that the melt mixing by a BMS is highly effective to act the required stress on overall resin. In addition, there is a good correlation between the incidence of undispersed glass-fiber bundles measured experimentally and the minimum value of distribution of the time-integrated stress calculated numerically. On the basis of the above results, we propose a method to predict the operating conditions in which the incident probability of undispersed glass-fiber bundles and thermal degradation are controlled.

  13. Performance of a hollow-fiber spiral disk for effective gas dispersion toward high mass transfer rate

    SciTech Connect

    Tsuchiya, Katsumi; Haryono, M.H.; Tomida, Tahei; Hatano, Hiroyuki; Oaki, Hiroshi

    1996-02-01

    Gas-dispersive capability of a hollow-fiber membrane, manufactured specifically for the use in fine bubbles generation, is tested for attaining high gas-liquid mass transfer rate under low-gas-throughput, shallow-sparging (at depths < 0.7 m) conditions. The hollow fiber is wound in a plane spiral form, each of which can be piled in a cylindrical module. A bubble column is used in the presence as well as absence of a draft tube, which the module can fit to and serve as part of. To enhance the effectiveness in the module`s generating fine bubbles, electrolytes are added to the liquid phase, water. Over a superficial gas velocity range of 0.1--2 mm/s, the hollow-fiber module (in comparison to conventional perforated-plate distributors) demonstrates, even with moderate gas-supply pressures (< 0.3 MPa), as high as 3-fold and 20-fold increases in the volumetric mass transfer coefficient in the absence and presence of the electrolytes, respectively. The former has been attained with a negligible increase in the gas holdup; the latter has accompanied a large ({approximately} 20-fold) increase in the gas holdup. While in the latter case the bubbles are very finely dispersed, the draft-tube model of operation secures still reasonable liquid circulation with nonclustering, spherical bubbles uniformly dispersed in each of the core and annular regions of the bubble column.

  14. Tropospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Buseck, P. R.; Schwartz, S. E.

    2003-12-01

    It is widely believed that "On a clear day you can see forever," as proclaimed in the 1965 Broadway musical of the same name. While an admittedly beautiful thought, we all know that this concept is only figurative. Aside from Earth's curvature and Rayleigh scattering by air molecules, aerosols - colloidal suspensions of solid or liquid particles in a gas - limit our vision. Even on the clearest day, there are billions of aerosol particles per cubic meter of air.Atmospheric aerosols are commonly referred to as smoke, dust, haze, and smog, terms that are loosely reflective of their origin and composition. Aerosol particles have arisen naturally for eons from sea spray, volcanic emissions, wind entrainment of mineral dust, wildfires, and gas-to-particle conversion of hydrocarbons from plants and dimethylsulfide from the oceans. However, over the industrial period, the natural background aerosol has been greatly augmented by anthropogenic contributions, i.e., those produced by human activities. One manifestation of this impact is reduced visibility (Figure 1). Thus, perhaps more than in other realms of geochemistry, when considering the composition of the troposphere one must consider the effects of these activities. The atmosphere has become a reservoir for vast quantities of anthropogenic emissions that exert important perturbations on it and on the planetary ecosystem in general. Consequently, much recent research focuses on the effects of human activities on the atmosphere and, through them, on the environment and Earth's climate. For these reasons consideration of the geochemistry of the atmosphere, and of atmospheric aerosols in particular, must include the effects of human activities. (201K)Figure 1. Impairment of visibility by aerosols. Photographs at Yosemite National Park, California, USA. (a) Low aerosol concentration (particulate matter of aerodynamic diameter less than 2.5 μm, PM2.5=0.3 μg m-3; particulate matter of aerodynamic diameter less than 10

  15. Aerosol fabrication methods for monodisperse nanoparticles

    DOEpatents

    Jiang, Xingmao; Brinker, C Jeffrey

    2014-10-21

    Exemplary embodiments provide materials and methods for forming monodisperse particles. In one embodiment, the monodisperse particles can be formed by first spraying a nanoparticle-containing dispersion into aerosol droplets and then heating the aerosol droplets in the presence of a shell precursor to form core-shell particles. By removing either the shell layer or the nanoparticle core of the core-shell particles, monodisperse nanoparticles can be formed.

  16. Performance of some DFT functionals with dispersion on modeling of the translational isomers of a solvent-switchable [2]rotaxane

    NASA Astrophysics Data System (ADS)

    Ivanov, Petko

    2016-03-01

    The balances of interactions were studied by computational methods in the translational isomers of a solvent switchable fullerene-stoppered [2]rotaxane (1) manifesting unexpected behavior, namely that due to favorable dispersion interactions the fullerene stopper becomes the second station upon change of the solvent. For comparison, another system, a pH switchable molecular shuttle (2), was also examined as an example of prevailing electrostatic interactions. Tested for 1 were five global hybrid Generalized Gradient Approximation functionals (B3LYP, B3LYP-D3, B3LYP-D3BJ, PBEh1PBE and APFD), one long-range corrected, range-separated functional with D2 empirical dispersion correction, ωB97XD, the Zhao-Truhlar's hybrid meta-GGA functional M06 with double the amount of nonlocal exchange (2X), and a pure functional, B97, with the Grimme's D3BJ dispersion (B97D3). The molecular mechanics method qualitatively correctly reproduced the behavior of the [2]rotaxanes, whereas the DFT models, except for M06-2X to some extent, failed in the case of significant dispersion interactions with participation of the fulleropyrrolidine stopper (rotaxane 1). Unexpectedly, the benzylic amide macrocycle tends to adopt preferentially 'boat'-like conformation in most of the cases. Four hydrogen bonds interconnect the axle with the wheel for the translational isomer with the macroring at the succinamide station (station II), whereas the number of hydrogen bonds vary for the isomer with the macroring at the fulleropyrrolidine stopper (station I) depending of the computational model used. The B3LYP and the PBEh1PBE results show strong preference of station II in the gas phase and in the model solvent DMSO. After including empirical dispersion correction, the translational isomer with the macroring at station I has the lower energy with B3LYP, both in the gas phase and in DMSO. The same result, but with higher preference of station I, was estimated with APFD, ωB97XD and B97D3. Only M06-2X

  17. A rapid ultrasound-assisted dispersive liquid-liquid microextraction followed by ultra-performance liquid chromatography for the simultaneous determination of seven benzodiazepines in human plasma samples.

    PubMed

    Fernández, Purificación; González, Cristina; Pena, M Teresa; Carro, Antonia M; Lorenzo, Rosa A

    2013-03-12

    A simple and efficient ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) method has been developed for the determination of seven benzodiazepines (alprazolam, bromazepam, clonazepam, diazepam, lorazepam, lormetazepam and tetrazepam) in human plasma samples. Chloroform and methanol were used as extractant and disperser solvents, respectively. The influence of several variables (e.g., type and volume of dispersant and extraction solvents, pH, ultrasonic time and ionic strength) was carefully evaluated and optimized, using an asymmetric screening design 3(2)4(2)//16. Analysis of extracts was performed by ultra-performance liquid chromatography coupled with photodiode array detection (UPLC-PDA). Under the optimum conditions, two reversed-phases, Shield RP18 and C18 columns were successfully tested, obtaining good linearity in a range of 0.01-5μgmL(-1), with correlation coefficients r>0.996. Quantification limits ranged between 4.3-13.2ngmL(-1) and 4.0-14.8ngmL(-1), were obtained for C18 and Shield RP18 columns, respectively. The optimized method exhibited a good precision level, with relative standard deviation values lower than 8%. The recoveries studied at two spiked levels, ranged from 71 to 102% for all considered compounds. The proposed method was successfully applied to the analysis of seven benzodiazepines in real human plasma samples. PMID:23452791

  18. Immunization by a bacterial aerosol.

    PubMed

    Garcia-Contreras, Lucila; Wong, Yun-Ling; Muttil, Pavan; Padilla, Danielle; Sadoff, Jerry; Derousse, Jessica; Germishuizen, Willem Andreas; Goonesekera, Sunali; Elbert, Katharina; Bloom, Barry R; Miller, Rich; Fourie, P Bernard; Hickey, Anthony; Edwards, David

    2008-03-25

    By manufacturing a single-particle system in two particulate forms (i.e., micrometer size and nanometer size), we have designed a bacterial vaccine form that exhibits improved efficacy of immunization. Microstructural properties are adapted to alter dispersive and aerosol properties independently. Dried "nanomicroparticle" vaccines possess two axes of nanoscale dimensions and a third axis of micrometer dimension; the last one permits effective micrometer-like physical dispersion, and the former provides alignment of the principal nanodimension particle axes with the direction of airflow. Particles formed with this combination of nano- and micrometer-scale dimensions possess a greater ability to aerosolize than particles of standard spherical isotropic shape and of similar geometric diameter. Here, we demonstrate effective application of this biomaterial by using the live attenuated tuberculosis vaccine bacille Calmette-Guérin (BCG). Prepared as a spray-dried nanomicroparticle aerosol, BCG vaccine exhibited high-efficiency delivery and peripheral lung targeting capacity from a low-cost and technically simple delivery system. Aerosol delivery of the BCG nanomicroparticle to normal guinea pigs subsequently challenged with virulent Mycobacterium tuberculosis significantly reduced bacterial burden and lung pathology both relative to untreated animals and to control animals immunized with the standard parenteral BCG. PMID:18344320

  19. Low Density Solvent-Based Dispersive Liquid-Liquid Microextraction for the Determination of Synthetic Antioxidants in Beverages by High-Performance Liquid Chromatography

    PubMed Central

    Çabuk, Hasan; Köktürk, Mustafa

    2013-01-01

    A simple and efficient method was established for the determination of synthetic antioxidants in beverages by using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography with ultraviolet detection. Butylated hydroxy toluene, butylated hydroxy anisole, and tert-butylhydroquinone were the antioxidants evaluated. Experimental parameters including extraction solvent, dispersive solvent, pH of sample solution, salt concentration, and extraction time were optimized. Under optimal conditions, the extraction recoveries ranged from 53 to 96%. Good linearity was observed by the square of correlation coefficients ranging from 0.9975 to 0.9997. The relative standard deviations ranged from 1.0 to 5.2% for all of the analytes. Limits of detection ranged from 0.85 to 2.73 ng mL−1. The method was successfully applied for determination of synthetic antioxidants in undiluted beverage samples with satisfactory recoveries. PMID:23853535

  20. Matrix solid-phase dispersion microextraction and determination by high-performance liquid chromatography with UV detection of pesticide residues in citrus fruit.

    PubMed

    Valenzuela, A I; Lorenzini, R; Redondo, M J; Font, G

    1999-04-16

    A multiresidue method based on matrix solid-phase dispersion (MSPD) microextraction was studied to determine the carbamate, benfuracarb, and urea insecticides, diflubenzuron, flufenoxuron hexaflumuron and hexythiazox, used in control of citrus pests. Optimisation of different parameters, such as the type of solid support for matrix dispersion, elution solvents and the clean-up step were carried out. The method used 0.5 g of orange sample, C8 bonded silica as MSPD sorbent and dichloromethane as eluting solvent. Recoveries, at spiked concentrations below the maximum residue levels established by Spanish Government, were between 74 and 84% with relative standard deviations ranging from 2 to 4%. The limits of quantification were from 0.15 to 0.25 microgram/g using high-performance liquid chromatography with UV detection at 200 nm. The method may be useful as a screening protocol for the determination of these newly developed pesticides in citrus samples. PMID:10327624

  1. Assessing the performance of dispersionless and dispersion-accounting methods: helium interaction with cluster models of the TiO2(110) surface.

    PubMed

    de Lara-Castells, María Pilar; Stoll, Hermann; Mitrushchenkov, Alexander O

    2014-08-21

    As a prototypical dispersion-dominated physisorption problem, we analyze here the performance of dispersionless and dispersion-accounting methodologies on the helium interaction with cluster models of the TiO2(110) surface. A special focus has been given to the dispersionless density functional dlDF and the dlDF+Das construction for the total interaction energy (K. Pernal, R. Podeswa, K. Patkowski, and K. Szalewicz, Phys. Rev. Lett. 2009, 109, 263201), where Das is an effective interatomic pairwise functional form for the dispersion. Likewise, the performance of symmetry-adapted perturbation theory (SAPT) method is evaluated, where the interacting monomers are described by density functional theory (DFT) with the dlDF, PBE, and PBE0 functionals. Our benchmarks include CCSD(T)-F12b calculations and comparative analysis on the nuclear bound states supported by the He-cluster potentials. Moreover, intra- and intermonomer correlation contributions to the physisorption interaction are analyzed through the method of increments (H. Stoll, J. Chem. Phys. 1992, 97, 8449) at the CCSD(T) level of theory. This method is further applied in conjunction with a partitioning of the Hartree-Fock interaction energy to estimate individual interaction energy components, comparing them with those obtained using the different SAPT(DFT) approaches. The cluster size evolution of dispersionless and dispersion-accounting energy components is then discussed, revealing the reduced role of the dispersionless interaction and intramonomer correlation when the extended nature of the surface is better accounted for. On the contrary, both post-Hartree-Fock and SAPT(DFT) results clearly demonstrate the high-transferability character of the effective pairwise dispersion interaction whatever the cluster model is. Our contribution also illustrates how the method of increments can be used as a valuable tool not only to achieve the accuracy of CCSD(T) calculations using large cluster models but also to

  2. New understanding and quantification of the regime dependence of aerosol-cloud interaction for studying aerosol indirect effects

    NASA Astrophysics Data System (ADS)

    Chen, Jingyi; Liu, Yangang; Zhang, Minghua; Peng, Yiran

    2016-02-01

    Aerosol indirect effects suffer from large uncertainty in climate models and among observations. This study focuses on two plausible factors: regime dependence of aerosol-cloud interactions and the effect of cloud droplet spectral shape. We show, using a new parcel model, that combined consideration of droplet number concentration (Nc) and relative dispersion (ɛ, ratio of standard deviation to mean radius of the cloud droplet size distribution) better characterizes the regime dependence of aerosol-cloud interactions than considering Nc alone. Given updraft velocity (w), ɛ increases with increasing aerosol number concentration (Na) in the aerosol-limited regime, peaks in the transitional regime, and decreases with further increasing Na in the updraft-limited regime. This new finding further reconciles contrasting observations in literature and reinforces the compensating role of dispersion effect. The nonmonotonic behavior of ɛ further quantifies the relationship between the transitional Na and w that separates the aerosol- and updraft-limited regimes.

  3. Ocular dispersion

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Noojin, Gary D.; Thomas, Robert J.; Stolarski, David J.; Rockwell, Benjamin A.; Welch, Ashley J.

    1999-06-01

    Spectrally resolved white-light interferometry (SRWLI) was used to measure the wavelength dependence of refractive index (i.e., dispersion) for various ocular components. The accuracy of the technique was assessed by measurement of fused silica and water, the refractive indices of which have been measured at several different wavelengths. The dispersion of bovine and rabbit aqueous and vitreous humor was measured from 400 to 1100 nm. Also, the dispersion was measured from 400 to 700 nm for aqueous and vitreous humor extracted from goat and rhesus monkey eyes. For the humors, the dispersion did not deviate significantly from water. In an additional experiment, the dispersion of aqueous and vitreous humor that had aged up to a month was compared to freshly harvested material. No difference was found between the fresh and aged media. An unsuccessful attempt was also made to use the technique for dispersion measurement of bovine cornea and lens. Future refinement may allow measurement of the dispersion of cornea and lens across the entire visible and near-infrared wavelength band. The principles of white- light interferometry including image analysis, measurement accuracy, and limitations of the technique, are discussed. In addition, alternate techniques and previous measurements of ocular dispersion are reviewed.

  4. Spatial pattern in aerosol insecticide deposition inside a flour mill

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aerosol insecticides are commonly used for management of stored-product pests inside food facilities, but the physical complexity of the interior of most food facilities may influence the dispersal and deposition of aerosol droplets and create spatial variation in efficacy. The spatial pattern in ae...

  5. A general circulation model (GCM) parameterization of Pinatubo aerosols

    SciTech Connect

    Lacis, A.A.; Carlson, B.E.; Mishchenko, M.I.

    1996-04-01

    The June 1991 volcanic eruption of Mt. Pinatubo is the largest and best documented global climate forcing experiment in recorded history. The time development and geographical dispersion of the aerosol has been closely monitored and sampled. Based on preliminary estimates of the Pinatubo aerosol loading, general circulation model predictions of the impact on global climate have been made.

  6. Ionic-liquid-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the forensic determination of methamphetamine in human urine.

    PubMed

    Wang, Ruifeng; Qi, Xiujuan; Zhao, Lei; Liu, Shimin; Gao, Shuang; Ma, Xiangyuan; Deng, Youquan

    2016-07-01

    Determination of methamphetamine in forensic laboratories is a major issue due to its health and social harm. In this work, a simple, sensitive, and environmentally friendly method based on ionic liquid dispersive liquid-liquid microextraction combined with high-performance liquid chromatography was established for the analysis of methamphetamine in human urine. 1-Octyl-3-methylimidazolium hexafluorophosphate with the help of disperser solvent methanol was selected as the microextraction solvent in this process. Various parameters affecting the extraction efficiency of methamphetamine were investigated systemically, including extraction solvent and its volume, disperser solvent and its volume, sample pH, extraction temperature, and centrifugal time. Under the optimized conditions, a good linearity was obtained in the concentration range of 10-1000 ng/mL with determination coefficient >0.99. The limit of detection calculated at a signal-to-noise ratio of 3 was 1.7 ng/mL and the relative standard deviations for six replicate experiments at three different concentration levels of 100, 500, and 1000 ng/mL were 6.4, 4.5, and 4.7%, respectively. Meanwhile, up to 220-fold enrichment factor of methamphetamine and acceptable extraction recovery (>80.0%) could be achieved. Furthermore, this method has been successfully employed for the sensitive detection of a urine sample from a suspected drug abuser. PMID:27135774

  7. [Simultaneous determination of four phthalate esters in water samples using ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography].

    PubMed

    Ma, Yanling; Chen, Lingxin; Ding, Yangjun; Ming, Yongfei; Li, Jinhua

    2013-02-01

    Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography (UA-DLLME-HPLC) was developed for the determination of four typical phthalate esters (PAEs). The analyzed PAEs included dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and di-n-octyl phthalate (DnOP). The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents, ultrasonic time, ionic strength and extraction time, were investigated. Enrichment factor (EF)was employed to evaluate the extraction efficiency. The conditions were finally chosen: CCl4 (40 microL)/ acetonitrile (1.0 mL) as extraction/dispersion solvents; 30 g/L NaCl; ultrasound/centrifugation of 5 min. Under the optimized extraction conditions, UA-DLLME exhibited strong enrichment ability for the four PAEs. The EFs for DMP, DEP, DBP and DnOP obtained were 71, 144, 169 and 159, respectively. The limits of detection were 3.78, 1.77, 3.07 and 3.30 microg/L for DMP, DEP, DBP and DnOP, respectively. The satisfactory recoveries for three water samples at three spiked levels ranged from 82.99%-114.47%, with the relative standard deviations of 1.93%-8.31%. It is a convenient, speedy, environmentally benign method for the routine analysis of PAEs in water samples. PMID:23697182

  8. Achieving extremely concentrated aqueous dispersions of graphene flakes and catalytically efficient graphene-metal nanoparticle hybrids with flavin mononucleotide as a high-performance stabilizer.

    PubMed

    Ayán-Varela, M; Paredes, J I; Guardia, L; Villar-Rodil, S; Munuera, J M; Díaz-González, M; Fernández-Sánchez, C; Martínez-Alonso, A; Tascón, J M D

    2015-05-20

    The stable dispersion of graphene flakes in an aqueous medium is highly desirable for the development of materials based on this two-dimensional carbon structure, but current production protocols that make use of a number of surfactants typically suffer from limitations regarding graphene concentration or the amount of surfactant required to colloidally stabilize the sheets. Here, we demonstrate that an innocuous and readily available derivative of vitamin B2, namely the sodium salt of flavin mononucleotide (FMNS), is a highly efficient dispersant in the preparation of aqueous dispersions of defect-free, few-layer graphene flakes. Most notably, graphene concentrations in water as high as ∼50 mg mL(-1) using low amounts of FMNS (FMNS/graphene mass ratios of about 0.04) could be attained, which facilitated the formation of free-standing graphene films displaying high electrical conductivity (∼52000 S m(-1)) without the need of carrying out thermal annealing or other types of post-treatment. The excellent performance of FMNS as a graphene dispersant could be attributed to the combined effect of strong adsorption on the sheets through the isoalloxazine moiety of the molecule and efficient colloidal stabilization provided by its negatively charged phosphate group. The FMNS-stabilized graphene sheets could be decorated with nanoparticles of several noble metals (Ag, Pd, and Pt), and the resulting hybrids exhibited a high catalytic activity in the reduction of nitroarenes and electroreduction of oxygen. Overall, the present results should expedite the processing and implementation of graphene in, e.g., conductive inks, composites, and hybrid materials with practical utility in a wide range of applications. PMID:25915172

  9. Bubble bursting as an aerosol generation mechanism during an oil spill in the deep-sea environment: molecular dynamics simulations of oil alkanes and dispersants in atmospheric air/salt water interfaces.

    PubMed

    Liyana-Arachchi, Thilanga P; Zhang, Zenghui; Ehrenhauser, Franz S; Avij, Paria; Valsaraj, Kalliat T; Hung, Francisco R

    2014-01-01

    Potential of mean force (PMF) calculations and molecular dynamics (MD) simulations were performed to investigate the properties of oil n-alkanes [i.e., n-pentadecane (C15), n-icosane (C20) and n-triacontane (C30)], as well as several surfactant species [i.e., the standard anionic surfactant sodium dodecyl sulfate (SDS), and three model dispersants similar to the Tween and Span species present in Corexit 9500A] at air/salt water interfaces. This study was motivated by the 2010 Deepwater Horizon (DWH) oil spill, and our simulation results show that, from the thermodynamic point of view, the n-alkanes and the model dispersants have a strong preference to remain at the air/salt water interface, as indicated by the presence of deep free energy minima at these interfaces. The free energy minimum of these n-alkanes becomes deeper as their chain length increases, and as the concentration of surfactant species at the interface increases. The n-alkanes tend to adopt a flat orientation and form aggregates at the bare air/salt water interface. When this interface is coated with surfactants, the n-alkanes tend to adopt more tilted orientations with respect to the vector normal to the interface. These simulation results are consistent with the experimental findings reported in the accompanying paper [Ehrenhauser et al., Environ. Sci.: Processes Impacts 2013, in press, (DOI: 10.1039/c3em00390f)]. The fact that these long-chain n-alkanes show a strong thermodynamic preference to remain at the air/salt water interfaces, especially if these interfaces are coated with surfactants, makes these species very likely to adsorb at the surface of bubbles or droplets and be ejected to the atmosphere by sea surface processes such as whitecaps (breaking waves) and bubble bursting. Finally, the experimental finding that more oil hydrocarbons are ejected when Corexit 9500A is present in the system is consistent with the deeper free energy minima observed for the n-alkanes at the air/salt water

  10. [Determination of benzoylurea and bishydrazide pesticide residues in vegetables by ultra performance liquid chromatography-tandem mass spectrometry with matrix solid phase dispersion].

    PubMed

    Han, Xiao; Lou, Xishan; Zhang, Li; Wang, Guoqing; Ma, Ming; Wang, Minglin

    2010-04-01

    A method for the determination of nine pesticides including benzoylureas (diflubenzuron, chlorobenzuron, triflumuron, teflubenzuron, flufenoxuron, chlorfluazuron, hexaflumuron) and bishydrazides (methoxyfenozide, tebufenozide) in vegetables was developed by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with matrix solid phase dispersion. The sample was graphitized with neutral alumina as dispersant and carbon black as purifying, and eluted with ethyl acetate. The separation was achieved by UPLC, and then the identification and quantification were performed using MS/MS with multiple-reaction monitoring and electrospray ionization in positive or negative mode. The following results were obtained: The calibration curves showed good linearity in the ranges of 1-100 microg/L with R2 > or = 0.99. The recoveries were 78.5%-112.8% at four spiked levels of 1, 5, 10, 100 microg/kg, and the relative standard deviations were 2.3%-10.2%. The limits of determination were 0.5-1.0 microg/kg. The method has the advantages of easy to operate, fast to perform, lower limits of quantification, consuming less sample and organic solvents. It can meet the demands of practical use for the rapid and simultaneous determination of benzoylureas and bishydrazides in vegetables. PMID:20712114

  11. Influence of temperature and artificially-created physical barriers on the efficacy of synergized pyrethrin aerosol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flour mills in the United States are utilizing synergized pyrethrin aerosol for management of stored product insects. However, the dispersal of the aerosol within a facility may be hampered by barriers created from machinery and other equipment that block dispersion. Additionally, seasonal temperatu...

  12. Atmospheric Aerosols

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Lawless, James G. (Technical Monitor)

    1994-01-01

    Aerosols, defined as particles and droplets suspended in air, are always present in the atmosphere. They are part of the earth-atmosphere climate system, because they interact with both incoming solar and outgoing terrestrial radiation. They do this directly through scattering and absorption, and indirectly through effects on clouds. Submicrometer aerosols usually predominate in terms of number of particles per unit volume of air. They have dimensions close to the wavelengths of visible light, and thus scatter radiation from the sun very effectively. They are produced in the atmosphere by chemical reactions of sulfur-, nitrogen- and carbon-containing gases of both natural and anthropogenic origins. Light absorption is dominated by particles containing elemental carbon (soot), produced by incomplete combustion of fossil fuels and by biomass burning. Light-scattering dominates globally, although absorption can be significant at high latitudes, particularly over highly reflective snow- or ice-covered surfaces. Other aerosol substances that may be locally important are those from volcanic eruptions, wildfires and windblown dust.

  13. Utilization of highly purified single wall carbon nanotubes dispersed in polymer thin films for an improved performance of an electrochemical glucose sensor.

    PubMed

    Goornavar, Virupaxi; Jeffers, Robert; Biradar, Santoshkumar; Ramesh, Govindarajan T

    2014-07-01

    In this work we report the improved performance an electrochemical glucose sensor based on a glassy carbon electrode (GCE) that has been modified with highly purified single wall carbon nanotubes (SWCNTs) dispersed in polyethyleneimine (PEI), polyethylene glycol (PEG) and polypyrrole (PPy). The single wall carbon nanotubes were purified by both thermal and chemical oxidation to achieve maximum purity of ~98% with no damage to the tubes. The SWCNTs were then dispersed by sonication in three different organic polymers (1.0mg/ml SWCNT in 1.0mg/ml of organic polymer). The stable suspension was coated onto the GCE and electrochemical characterization was performed by Cyclic Voltammetry (CV) and Amperometry. The electroactive enzyme glucose oxidase (GOx) was immobilized on the surface of the GCE/(organic polymer-SWCNT) electrode. The amperometric detection of glucose was carried out at 0.7 V versus Ag/AgCl. The GCE/(SWCNT-PEI, PEG, PPY) gave a detection limit of 0.2,633 μM, 0.434 μM, and 0.9,617 μM, and sensitivities of 0.2411 ± 0.0033 μA mM(-1), r(2)=0.9984, 0.08164 ± 0.001129 μA mM(-1), r(2)=0.9975, 0.04189 ± 0.00087 μA mM(-1), and r(2)=0.9944 respectively and a response time of less than 5s. The use of purified SWCNTs has several advantages, including fast electron transfer rate and stability in the immobilized enzyme. The significant enhancement of the SWCNT modified electrode as a glucose sensor can be attributed to the superior conductivity and large surface area of the well dispersed purified SWCNTs. PMID:24857497

  14. Aerosol extinction measurements with CO2-lidar

    NASA Technical Reports Server (NTRS)

    Hagard, Arne; Persson, Rolf

    1992-01-01

    With the aim to develop a model for infrared extinction due to aerosols in slant paths in the lower atmosphere we perform measurements with a CO2-lidar. Earlier measurements with a transmissometer along horizontal paths have been used to develop relations between aerosol extinction and meteorological parameters. With the lidar measurements we hope to develop corresponding relations for altitude profiles of the aerosol extinction in the infrared. An important application is prediction of detection range for infrared imaging systems.

  15. Determination of calcium stearate in polyolefin samples by gas chromatographic technique after performing dispersive liquid-liquid microextraction.

    PubMed

    Ranji, Ali; Ghorbani Ravandi, Mahboobeh; Farajzadeh, Mir Ali

    2008-05-01

    In this study, a gas chromatographic method is presented for the determination of calcium stearate after its conversion to stearic acid in a polymeric matrix. A solution of hydrochloric acid in 2-propanol is used as an extracting solvent of calcium stearate and its converter to stearic acid. For stearic acid preconcentration before its injection to a separation system, a recently presented extraction method, dispersive liquid-liquid microextraction, using carbon tetrachloride as an extracting solvent is used. Finally, 1 microL of the organic phase collected at the bottom of a conical test tube after centrifuging is injected into a gas chromatograph (GC) for quantification. This method has a relatively broad linear dynamic range (50 - 2000 mg/L) with a limit of detection (LOD) of 15 mg/L for stearic acid in solution. The LOD of the proposed method in a polymeric sample using 10 mg of polymer is 60 ppm as calcium stearate. Some effective parameters, such as the time and temperature of heating, the concentration of hydrochloric acid and the volume of distilled water, were studied. PMID:18469468

  16. Selenium speciation in tea by dispersive liquid-liquid microextraction coupled to high-performance liquid chromatography after derivatization with 2,3-diaminonaphthalene.

    PubMed

    Zhou, Qingxiang; Lei, Man; Li, Jing; Wang, Mengyun; Zhao, Danchen; Xing, An; Zhao, Kuifu

    2015-05-01

    Selenium is an important element for human health, and it is present in many natural drinks and foods. Present study described a new method using dispersive liquid-liquid microextraction prior to high-performance liquid chromatography with a UV variable wavelength detector for the determination of the total selenium, Se(IV), Se(VI), and total organoselenium in tea samples. In the procedure, 2,3-diaminonaphthalene was used as the chelating reagent, 400 μL acetonitrile was used as the disperser solvent and 60 μL chlorobenzene was used as the extraction solvent. The complex of Se(IV) and 2,3-diaminonaphthalene in the final extracted phase was analyzed by high-performance liquid chromatography. The factors influencing the derivatization and microextraction were investigated. Under the optimal conditions, the limit of detection was 0.11 μg/L for Se(IV) and the linearity range was in the range of 0.5-40 μg/L. This method was successfully applied to the determination of selenium in four tea samples with spiked recoveries ranging from 91.3 to 100%. PMID:25677605

  17. Platinum-TM (TM = Fe, Co) alloy nanoparticles dispersed nitrogen doped (reduced graphene oxide-multiwalled carbon nanotube) hybrid structure cathode electrocatalysts for high performance PEMFC applications.

    PubMed

    Vinayan, B P; Ramaprabhu, S

    2013-06-01

    The efforts to push proton exchange membrane fuel cells (PEMFC) for commercial applications are being undertaken globally. In PEMFC, the sluggish kinetics of oxygen reduction reactions (ORR) at the cathode can be improved by the alloying of platinum with 3d-transition metals (TM = Fe, Co, etc.) and with nitrogen doping, and in the present work we have combined both of these aspects. We describe a facile method for the synthesis of a nitrogen doped (reduced graphene oxide (rGO)-multiwalled carbon nanotubes (MWNTs)) hybrid structure (N-(G-MWNTs)) by the uniform coating of a nitrogen containing polymer over the surface of the hybrid structure (positively surface charged rGO-negatively surface charged MWNTs) followed by the pyrolysis of these (rGO-MWNTs) hybrid structure-polymer composites. The N-(G-MWNTs) hybrid structure is used as a catalyst support for the dispersion of platinum (Pt), platinum-iron (Pt3Fe) and platinum-cobalt (Pt3Co) alloy nanoparticles. The PEMFC performances of Pt-TM alloy nanoparticle dispersed N-(G-MWNTs) hybrid structure electrocatalysts are 5.0 times higher than that of commercial Pt-C electrocatalysts along with very good stability under acidic environment conditions. This work demonstrates a considerable improvement in performance compared to existing cathode electrocatalysts being used in PEMFC and can be extended to the synthesis of metal, metal oxides or metal alloy nanoparticle decorated nitrogen doped carbon nanostructures for various electrochemical energy applications. PMID:23644681

  18. Temporal consistency of lidar observations during aerosol transport events in the framework of the ChArMEx/ADRIMED campaign at Minorca in June 2013

    NASA Astrophysics Data System (ADS)

    Chazette, Patrick; Totems, Julien; Ancellet, Gérard; Pelon, Jacques; Sicard, Michaël

    2016-03-01

    We performed synergetic daytime and nighttime active and passive remote-sensing observations at Minorca (Balearic Islands, Spain), over more than 3 weeks during the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Effect in the Mediterranean (ChArMEx/ADRIMED) special observation period (SOP 1a, June-July 2013). We characterized the aerosol optical properties and type in the low and middle troposphere using an automated procedure combining Rayleigh-Mie-Raman lidar (355, 387 and 407 nm) with depolarization (355 nm) and AERONET Cimel® sun-photometer data. Results show a high variability due to varying dynamical forcing. The mean column-averaged lidar backscatter-to-extinction ratio (BER) was close to 0.024 sr-1 (lidar ratio of ˜ 41.7 sr), with a large dispersion of ±33 % over the whole observation period due to changing atmospheric transport regimes and aerosol sources. The ground-based remote-sensing measurements, coupled with satellite observations, allowed the documentation of (i) dust particles up to 5 km (above sea level) in altitude originating from Morocco and Algeria from 15 to 18 June with a peak in aerosol optical thickness (AOT) of 0.25 ± 0.05 at 355 nm, (ii) a long-range transport of biomass burning aerosol (AOT = 0.18 ± 0.16) related to North American forest fires detected from 26 to 28 June 2013 by the lidar between 2 and 7 km and (iii) mixture of local sources including marine aerosol particles and pollution from Spain. During the biomass burning event, the high value of the particle depolarization ratio (8-14 %) may imply the presence of dust-like particles mixed with the biomass burning aerosols in the mid-troposphere. For the field campaign period, we also show linearity with SEVIRI retrievals of the aerosol optical thickness despite 35 % relative bias, which is discussed as a function of aerosol type.

  19. Temporal consistency of lidar observables during aerosol transport events in the framework of the ChArMEx/ADRIMED campaign at Menorca Island in June 2013

    NASA Astrophysics Data System (ADS)

    Chazette, P.; Totems, J.; Ancellet, G.; Pelon, J.; Sicard, M.

    2015-11-01

    We performed synergetic daytime and night-time active and passive remote sensing observations at Menorca (Balearic Island, Spain), over more than 3 weeks during the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Effect in the Mediterranean (ChArMEx/ADRIMED) special observation period (SOP 1a, June-July 2013). We characterized the aerosol optical properties and type in the low and middle troposphere using an automated procedure combining Rayleigh-Mie-Raman lidar (355, 387 and 407 nm) with depolarization (355 nm) and AERONET Cimel® sun-photometer data. Results show a high variability due to varying dynamical forcing. The mean column-averaged lidar backscatter-to-extinction ratio (BER) was close to 0.024 sr-1 (lidar ratio of ∼ 41.7 sr), with a large dispersion of ±33 % over the whole observation period due to changing atmospheric transport regimes and aerosol sources. The ground-based remote sensing measurements, coupled with satellite observations, allowed to document (i) dust particles up to 5 km a.s.l. in altitude originating from Morocco and Algeria from 15 to 18 June with a peak in aerosol optical thickness (AOT) of 0.25 ± 0.05 at 355 nm, (ii) a long-range transport of biomass burning aerosol (AOT = 0.18 ± 0.16) related to North American forest fires detected from 26 to 28 June 2013 by the lidar between 2 and 7 km and (iii) mixture of local sources including marine aerosol particles and pollution from Spain. During the biomass burning event, the high value of the particle depolarization ratio (8-14 %) may imply the presence of dust-like particles mixed with the biomass burning aerosols in the mid troposphere. We show also linearity with SEVIRI retrievals of the aerosol optical thickness within 35 % relative bias, which is discussed as a function of aerosol type.

  20. Lead Isotopic Composition and Trace Metals in Aerosols for Source Apportionment

    NASA Astrophysics Data System (ADS)

    Chien, C. T.; Paytan, A.

    2014-12-01

    Transported thousands of miles away from their source, aerosols can be dispersed and deposition throughout the Earth's surface. Aerosols from natural and industrial sources have different characteristics and health impacts thus it is important to identify their sources. The lead isotopic composition and trace metals in aerosol samples collected in different regions and periods around the world can help us better understand spatial and seasonal variation of aerosol sources. Aerosol samples collected in California, Bermuda, China and the Red Sea have been analyzed. The trace metal and Pb isotopes in these samples provide information regarding the various sources of aerosols to these sites.

  1. Cloud and Aerosol Lidar Channel Design and Performance of the Geoscience Laser Altimeter System on the ICESat Mission

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Abshire, James B.; Krainak, Michael A.; Spinhirne, James D.; Palm, Steve S.; Lancaster, Redgie S.; Allan, Graham R.

    2004-01-01

    The design of the 532 and 1064nm wavelength atmosphere lidar channels of the Geoscience Laser Altimeter System on the ICESat spacecraft is described. The lidar channel performance per on orbit measurements data will be presented.

  2. Characterization Of Industrial And Background Aerosols In The RhÔne-alpes Region Using Laser Remote Sensing Device.

    NASA Astrophysics Data System (ADS)

    Geffroy, S.; Rairoux, P.; Mondelain, D.; Boutou, V.; Wolf, J.-P.; Frejafon, E.

    Lack of reliable database on aerosol emission and dispersion is one of the main rea- sons for the incertitude of the impact of aerosol on the climate change. International statements and policies requested improvement on the global and on the regional scale. This new project is related to the characterisation of the spatial and time distribution of the aerosols in the Rhône-Alpes region. Actually, aerosols monitoring is mainly performed at ground level in this region and only few studies have been performed on the 3D distribution of urban aerosols (soot) using remote sensing laser device. The Rhône-Alpes region is representative for the regional impact of industry and traffic emission and also for the long-range transport of pollution over the East part of the Alps. The environmental situation of the region in term of sources and localization is especially dominated by: heavy traffic with several motorways (A6 from Paris, A7 to Marseille - both downtown - and A43 to the Alps and Italy) and industrial pollu- tion in particular for Lyon (refinery and several chemistry plants) and Saint Etienne agglomerations, which have a direct impact on the local air quality and also on the regional and national scale. Characterization of the aerosol load and dispersion in this region will be achieved applying two schemes. The first one will be related to the 3D quantitative characterization of diffuse aerosol emission in the industrial areas. Mon- itoring will be performed using a UV-infrared lidar remote sensing device. Emission cadastre elaboration and microphysical characterisation of the emission will be estab- lished. Direct access to several aerosol distribution modes will be used to describe the aerosol population dynamic: sedimentation, transport and aggregation. Studies on the direct impact of the emission on the region will be achieved coupling the 3D and ground level monitoring with dispersion model. The second scheme will be related to the long term remote sensing of

  3. Ice Nucleation Activity of Various Agricultural Soil Dust Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Schiebel, Thea; Höhler, Kristina; Funk, Roger; Hill, Thomas C. J.; Levin, Ezra J. T.; Nadolny, Jens; Steinke, Isabelle; Suski, Kaitlyn J.; Ullrich, Romy; Wagner, Robert; Weber, Ines; DeMott, Paul J.; Möhler, Ottmar

    2016-04-01

    Recent investigations at the cloud simulation chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) suggest that agricultural soil dust has an ice nucleation ability that is enhanced up to a factor of 10 compared to desert dust, especially at temperatures above -26 °C (Steinke et al., in preparation for submission). This enhancement might be caused by the contribution of very ice-active biological particles. In addition, soil dust aerosol particles often contain a considerably higher amount of organic matter compared to desert dust particles. To test agricultural soil dust as a source of ice nucleating particles, especially for ice formation in warm clouds, we conducted a series of laboratory measurements with different soil dust samples to extend the existing AIDA dataset. The AIDA has a volume of 84 m3 and operates under atmospherically relevant conditions over wide ranges of temperature, pressure and humidity. By controlled adiabatic expansions, the ascent of an air parcel in the troposphere can be simulated. As a supplement to the AIDA facility, we use the INKA (Ice Nucleation Instrument of the KArlsruhe Institute of Technology) continuous flow diffusion chamber based on the design by Rogers (1988) to expose the sampled aerosol particles to a continuously increasing saturation ratio by keeping the aerosol temperature constant. For our experiments, soil dust was dry dispersed into the AIDA vessel. First, fast saturation ratio scans at different temperatures were performed with INKA, sampling soil dust aerosol particles directly from the AIDA vessel. Then, we conducted the AIDA expansion experiment starting at a preset temperature. The combination of these two different methods provides a robust data set on the temperature-dependent ice activity of various agriculture soil dust aerosol particles with a special focus on relatively high temperatures. In addition, to extend the data set, we investigated the role of biological and organic matter in more

  4. Binary Solvents Dispersive Liquid—Liquid Microextraction (BS-DLLME) Method for Determination of Tramadol in Urine Using High-Performance Liquid Chromatography

    PubMed Central

    2014-01-01

    Background Tramadol is an opioid, synthetic analog of codeine and has been used for the treatment of acute or chronic pain may be abused. In this work, a developed Dispersive liquid liquid microextraction (DLLME) as binary solvents-based dispersive liquid-liquid microextraction (BS-DLLME) combined with high performance liquid chromatography (HPLC) with fluorescence detection (FD) was employed for determination of tramadol in the urine samples. This procedure involves the use of an appropriate mixture of binary extraction solvents (70 μL CHCl3 and 30 μL ethyl acetate) and disperser solvent (600 μL acetone) for the formation of cloudy solution in 5 ml urine sample comprising tramadol and NaCl (7.5%, w/v). After centrifuging, the small droplets of extraction solvents were precipitated. In the final step, the HPLC with fluorescence detection was used for determination of tramadol in the precipitated phase. Results Various factors on the efficiency of the proposed procedure were investigated and optimized. The detection limit (S/N = 3) and quantification limit (S/N = 10) were found 0.2 and 0.9 μg/L, respectively. The relative standard deviations (RSD) for the extraction of 30 μg L of tramadol was found 4.1% (n = 6). The relative recoveries of tramadol from urine samples at spiking levels of 10, 30 and 60 μg/L were in the range of 95.6 – 99.6%. Conclusions Compared with other methods, this method provides good figures of merit such as good repeatability, high extraction efficiency, short analysis time, simple procedure and can be used as microextraction technique for routine analysis in clinical laboratories. PMID:24495475

  5. Determination of isothiazolinone preservatives in cosmetics and household products by matrix solid-phase dispersion followed by high-performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Alvarez-Rivera, Gerardo; Dagnac, Thierry; Lores, Marta; Garcia-Jares, Carmen; Sanchez-Prado, Lucia; Lamas, J Pablo; Llompart, Maria

    2012-12-28

    In this work, the development of a new efficient methodology applying, for the first time, matrix solid phase dispersion (MSPD) for the determination of sensitizer isothiazolinone biocides in cosmetics and household products - 2-methyl-3-isothiazolinone (MI), 5-chloro-2-methyl-3-isothiazolinone (CMI), 1,2-benzisothiazolinone (BzI) and 2-octyl-3-isothiazolinone (OI) - is described. The main factors affecting the MSPD extraction procedure, the dispersive phase and the elution solvent, are assessed and optimized through a multicategorical experimental design, using a real cosmetic sample. The most suitable extraction conditions comprise the use of 2g of florisil as dispersive phase and 5 mL of methanol as elution solvent. Subsequently, the extract is readily analyzed by HPLC-MS/MS without any further clean-up or concentration steps. Method performance was evaluated demonstrating to have a broad linear range (R(2)>0.9980) and limits of detection (LOD) and quantification (LOQ) at the low nanogram per gram level, which are well below the required limits for UE regulation compliance. Satisfactory recoveries above 80%, except for MI (mean values close to 60%), were obtained. In all cases, the method precision (% RSD) was lower than 7%, making this low cost extraction method reliable for routine control. The validated methodology was finally applied to the analysis of a wide variety of cosmetics and household products. Most of the real samples analyzed have been shown to comply with the current European Cosmetic Regulation, although the results obtained for some rinse-off cosmetics (e.g. baby care products) revealed high isothiazolinone content. PMID:23182288

  6. Fabrication of uniformly dispersed Ag nanoparticles loaded TiO{sub 2} nanotube arrays for enhancing photoelectrochemical and photocatalytic performances under visible light irradiation

    SciTech Connect

    Yi, Junhui; Zhang, Shengsen; Wang, Hongjuan; Yu, Hao; Peng, Feng

    2014-12-15

    Graphical abstract: Uniformly dispersed Ag nanoparticles (NPs) were successfully loaded on both the outer and inner surface of the TiO{sub 2} nanotube arrays (NTs) through a simple polyol method, which exhibited the enhanced photoelectrochemical and photocatalytic performances under visible-light irradiation due to the more effective separation of photo-generated electron–hole pairs and faster interfacial charge transfer. - Highlights: • Highly dispersed Ag nanoparticles (NPs) are successfully prepared by polyol method. • Ag NPs are uniformly loaded on the surface of the TiO{sub 2} nanotube arrays (NTs). • Ag/TiO{sub 2}-NTs exhibit the enhanced photocatalytic activity under visible-light. • The enhanced photocurrent is explained by electrochemical impedance spectroscopy. - Abstract: Uniformly dispersed Ag nanoparticles (NPs) were successfully loaded on both the outer and inner surface of the TiO{sub 2} nanotube arrays (NTs) through a simple polyol method. The as-prepared Ag/TiO{sub 2}-NTs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV–vis diffusion reflectance spectroscopy. Photoelectrochemical behaviors were investigated via photocurrent response and electrochemical impedance spectroscopy (EIS). Photocatalytic activity of Ag/TiO{sub 2}-NTs was evaluated by degradation of acid orange II under visible light irradiation. The results showed that photocatalytic efficiency of Ag/TiO{sub 2}-NTs is more than 5 times higher than that of pure TiO{sub 2} NTs. Comparing with the electrochemical deposition method, the photocatalytic activity of Ag/TiO{sub 2}-NTs prepared by polyol method has been obviously increased.

  7. Development of hot melt co-formulated antimalarial solid dispersion system in fixed dose form (ARLUMELT): Evaluating amorphous state and in vivo performance.

    PubMed

    Fule, Ritesh; Dhamecha, Dinesh; Maniruzzaman, Mohammed; Khale, Anubha; Amin, Purnima

    2015-12-30

    The aim of this study was to investigate the industrial feasibility of developing a co-formulated solid dispersion (SD) containing two antimalarial drugs artemether (ARTM) and lumefantrine (LUMF). Soluplus(®) (polyethyleneglycol-polyvinyl caprolactam-polyvinyl acetate grafted copolymer) was used as primary carrier matrices via hot-melt extrusion processing to improve solubility profile and the oral bioavailability of the combination. Based on the preliminary screening, the optimized quantities of PEG 400, Lutrol F127 and Lutrol F68 were incorporated as surfactant with soluplus in different ratios to improve extrudability, increase wettability and the melt viscosity of the HME process. Soluplus(®) was proved to successfully stabilize both the drugs inside its polymeric network during extrusion via forming a stable solid dispersion. Physicochemical properties of the APIs and the SDs characterized by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), MDSC, FTIR spectroscopy and X-ray diffractometry (XRD) revealed the amorphous existence of the drug in all SDs developed. Molecular level morphology of solid dispersion characterized by using advanced physicochemical characterization techniques such as Raman spectroscopy, atomic force microscopy (AFM) and 2D NMR showed the transformation of the crystalline drugs to its stable amorphous state. All manufactured SDs retained their amorphicity even after a stability study conducted in accelerated condition over 6 months. The solubility and in vitro dissolution performance of both drugs in SD formulations was improved significantly when compared with pure drugs and marketed product while the in vivo studies revealed the same.The pharmacokinetic studies in rats revealed that the SD (AL1) shows a 44.12-65.24 folds increase in the AUC(0-72) and 42.87-172.61 folds increase in Cmax compared to that of pure drugs and a better bioavailability than that of commercial product. PMID:26471056

  8. Applications of UV Scattering and Absorbing Aerosol Indices

    NASA Astrophysics Data System (ADS)

    Penning de Vries, M.; Beirle, S.; Wagner, T.

    2009-04-01

    Aerosols cause a substantial amount of radiative forcing, but quantifying this amount is difficult: determining aerosol concentrations in the atmosphere and, especially, characterizing their (optical) properties, has proved to be quite a challenge. A good way to monitor aerosol characteristics on a global scale is to perform satellite remote sensing. Most satellite aerosol retrieval algorithms are based on fitting of aerosol-induced changes in earth reflectance, which are usually subtle and have a smooth wavelength dependence. In such algorithms certain aerosol models are assumed, where optical parameters such as single scattering albedo, asymmetry parameter and size parameter (or Angstrom exponent) are defined. Another, semi-quantitative technique for detecting aerosols is the calculation of UV Aerosol Indices (UVAI). The Absorbing and Scattering Aerosol Indices detect "UV-absorbing" aerosols (most notably mineral dust, black and brown carbon particles) and "scattering" aerosols (sulfate and secondary organic aerosol particles), respectively. UVAI are essentially a measure of the contrast between two wavelengths in the UV range. The advantages of UVAI are: they can be determined in the presence of clouds, they are rather insensitive to surface type, and they are very sensitive to aerosols. The Absorbing Aerosol Index (AAI) has been in use for over a decade, and the Scattering Aerosol Index (SAI) was recently introduced by our group. Whereas the AAI is mainly used to detect desert dust and biomass burning plumes, the SAI can be used to study regions with high concentrations of non-absorbing aerosols, either anthropogenic (e.g. sulfate aerosols in eastern China) or biogenic (e.g. secondary organic aerosols formed from VOCs emitted by plants). Here we will present our recent UVAI results from SCIAMACHY: we will discuss the seasonal trend of SAI, and correlate our UVAI data with other datasets such as trace gases (HCHO, NO2, CO) and fire counts from the (A

  9. Validation of MODIS Aerosol Retrieval Over Ocean

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine A.; Tanre, Didier; Kaufman, Yoram J.; Ichoku, Charles; Mattoo, Shana; Levy, Robert; Chu, D. Allen; Holben, Brent N.; Dubovik, Oleg; Ahmad, Ziauddin; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) algorithm for determining aerosol characteristics over ocean is performing with remarkable accuracy. A two-month data set of MODIS retrievals co-located with observations from the AErosol RObotic NETwork (AERONET) ground-based sunphotometer network provides the necessary validation. Spectral radiation measured by MODIS (in the range 550 - 2100 nm) is used to retrieve the aerosol optical thickness, effective particle radius and ratio between the submicron and micron size particles. MODIS-retrieved aerosol optical thickness at 660 nm and 870 nm fall within the expected uncertainty, with the ensemble average at 660 nm differing by only 2% from the AERONET observations and having virtually no offset. MODIS retrievals of aerosol effective radius agree with AERONET retrievals to within +/- 0.10 micrometers, while MODIS-derived ratios between large and small mode aerosol show definite correlation with ratios derived from AERONET data.

  10. Solitonization of a dispersive wave.

    PubMed

    Braud, F; Conforti, M; Cassez, A; Mussot, A; Kudlinski, A

    2016-04-01

    We report the observation of a nonlinear propagation scenario in which a dispersive wave is transformed into a fundamental soliton in an axially varying optical fiber. The dispersive wave is initially emitted in the normal dispersion region and the fiber properties change longitudinally so that the dispersion becomes anomalous at the dispersive wave wavelength, which allows it to be transformed into a soliton. The solitonic nature of the field is demonstrated by solving the direct Zakharov-Shabat scattering problem. Experimental characterization performed in spectral and temporal domains show evidence of the solitonization process in an axially varying photonic crystal fiber. PMID:27192249

  11. A non-derivative method for the quantitative analysis of isosteroidal alkaloids from Fritillaria by high performance liquid chromatography combined with charged aerosol detection.

    PubMed

    Long, Zhen; Guo, Zhimou; Acworth, Ian N; Liu, Xiaoda; Jin, Yan; Liu, Xingguo; Liu, Lvye; Liang, Lina

    2016-05-01

    A non-derivative method was developed for the qualitative and quantitative analysis of isosteroidal alkaloids from Fritillaria thunbergii. During method development the performance of two universal detectors, the charged aerosol detector (CAD) and evaporative light scattering detector (ELSD), were evaluated. The CAD was found to be 30 to 55 times more sensitive than ELSD enabling the measurement of low levels of reference compound impurities that could not be detected by ELSD. The peak area percent of the reference compound, peimisine, obtained by CAD was 50.10%, but 91.66% by ELSD showing that CAD is suitable to estimate the presence of impurities. The CAD showed good reproducibility with overall intra- and inter-day peak area RSD values of less than 1.8% and 2.7%, respectively and had a linear dynamic range of up to 4 orders of magnitude (0.06-44mg/L) for peimine and peiminine. The optimized method was used for the quantitative analysis of peimine and peiminine from F. thunbergii. PMID:26946033

  12. Rapid and sensitive quantification of levoglucosan in aerosols by high-performance anion-exchange chromatography with positive electrospray ionization mass spectrometry (HPAEC-positive ESI-MS)

    NASA Astrophysics Data System (ADS)

    Asakawa, Daichi; Furuichi, Yuko; Yamamoto, Atsushi; Oku, Yuichiro; Funasaka, Kunihiro

    2015-12-01

    A convenient quantification method for underivatized levoglucosan, which is a tracer for biomass burning influenced particulate matter (PM), has been established using high-performance anion-exchange chromatography (HPAEC) coupled to positive electrospray ionization mass spectrometry ((+)ESI-MS). Levoglucosan was chromatographically separated from its isomers (mannosan and galactosan) and detected selectively with positive ESI-MS. Limits of detection and quantification for this method were 0.40 and 1.3 ng mL-1, respectively. A comparison of simultaneous measurements by this method and conventional derivatization gas chromatography/mass spectrometry showed a good linearity with a slope of 1.008 and a determination coefficient of 0.9932. The developed method was applied to ambient suspended particulate matter hourly collected by continuous particulate monitors at 10 stations. The hourly concentration of levoglucosan during August 9-11, 2011, was 1.7-918 ng m-3 and its distribution indicated the transportation of biomass burning aerosols of a forest fire. This is the first report of horizontal distribution of the hourly levoglucosan concentration in Japan.

  13. Hygroscopic, Morphological, and Chemical Properties of Agricultural Aerosols

    NASA Astrophysics Data System (ADS)

    Hiranuma, N.; Brooks, S. D.; Cheek, L.; Thornton, D. C.; Auvermann, B. W.; Littleton, R.

    2007-12-01

    Agricultural fugitive dust is a significant source of localized air pollution in the semi-arid southern Great Plains. In the Texas Panhandle, daily episodes of ground-level fugitive dust emissions from the cattle feedlots are routinely observed in conjunction with increased cattle activity in the late afternoons and early evenings. We conducted a field study to characterize size-selected agricultural aerosols with respect to hygroscopic, morphological, and chemical properties and to attempt to identify any correlations between these properties. To explore the hygroscopic nature of agricultural particles, we have collected size-resolved aerosol samples using a cascade impactor system at a cattle feedlot in the Texas Panhandle and have used the Environmental Scanning Electron Microscope (ESEM) to determine the water uptake by individual particles in those samples as a function of relative humidity. To characterize the size distribution of agricultural aerosols as a function of time, A GRIMM aerosol spectrometer and Sequential Mobility Particle Sizer and Counter (SMPS) measurements were simultaneously performed in an overall size range of 11 nm to 20 µm diameters at a cattle feedlot. Complementary determination of the elemental composition of individual particles was performed using Energy Dispersive X-ray Spectroscopy (EDS). In addition to the EDS analysis, an ammonia scrubber was used to collect ammonia and ammonium in the gas and particulate phases, respectively. The concentration of these species was quantified offline via UV spectrophotometry at 640 nanometers. The results of this study will provide important particulate emission data from a feedyard, needed to improve our understanding of the role of agricultural particulates in local and regional air quality.

  14. Radon tower measurements in a Spanish coastal site for Lagrangian particle dispersion model inter-comparison and performance assessment at the mesoscale

    NASA Astrophysics Data System (ADS)

    Vargas, Arturo; Arnold, Delia; Ángel Hernández-Ceballos, Miguel; Adame, José Antonio; Morton, Don; Grossi, Claudia; Schicker, Irene; de la Morena, Benito; Bolivar, Juan Pedro; Gil, Manuel

    2013-04-01

    In the framework of the spanish research project "Development and validation of advanced atmospheric dispersion models for their application in radiological emergency systems" (ref:CGL2008-00473) /CLI, the "El Arenosillo" tower, belonging to the National Institute for Aerospace Technology (INTA) was equiped with radon monitors and, since 2011, is providing reliable and high quality measurements of Rn-222 air concentrations on an hourly basis at two elevations, namely 10 and 100 m above ground level. This radionuclide data is accompanied by continuous meteorological data including temperature, humidity, pressure and wind speed / direction. The location of the station, at the very edge of the Southern Europe, exposed to continental (rural, industrial and urban), marine and Saharan air masses, together with the Rn-222 and meteorological measurements, make it particularly attractive to study the transport phenomena and the performance of meteorological and transport models at all scales, as well as to carry out studies on the vertical structure of the atmosphere in a coastal site. In this context, two intensive measurement campaigns, including radio soundings, were performed during October 2011 and May 2012, allowing the comparison and a better understanding of the Rn-222 measurements under different meteorological conditions. This work will present a first evaluation of the two campaigns at the INTA station, analyzing the evolution of Rn-222 concentration data and the results of the meteorological numerical modelling of those episodes using the Weather Research and Forecasting (WRF) model with different parameterizations. Finally, the atmospheric dispersion model inter-comparison (HYSPLIT-WRF and FLEXPART-WRF) with Rn-222 as a tracer is performed.

  15. Dispersive liquid-liquid microextraction combined with ultra-high performance liquid chromatography for the simultaneous determination of 25 sulfonamide and quinolone antibiotics in water samples.

    PubMed

    Herrera-Herrera, Antonio V; Hernández-Borges, Javier; Borges-Miquel, Teresa M; Rodríguez-Delgado, Miguel Ángel

    2013-03-01

    In this work, a dispersive liquid-liquid microextraction (DLLME) procedure combined with ultra-high performance liquid chromatography with diode-array detection was developed to determine 25 antibiotics in mineral and run-off waters. Optimum DLLME conditions (5 mL of water at pH=7.6, 20% (w/v) NaCl, 685 μL of CHCl₃ as extractant solvent, and 1250 μL of ACN as disperser solvent) allowed the repeatable, accurate and selective determination of 11 sulfonamides (sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole, sulfadimidin, sulfamethoxypyridazine, sulfadoxine, sulfamethoxazole, sulfisoxazole, sulfadimethoxine and sulfaquinoxaline) and 14 quinolones (pipemidic acid, marbofloxacin, fleroxacin, levofloxacin, pefloxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, moxifloxacin, oxolinic acid and flumequine). The method was validated by means of the obtention of calibration curves of the whole method as well as a recovery study at two levels of concentration. The LODs of the method were in the range 0.35-10.5 μg/L with recoveries between 78% and 117%. PMID:23246932

  16. Development and comparison of two dispersive liquid-liquid microextraction techniques coupled to high performance liquid chromatography for the rapid analysis of bisphenol A in edible oils.

    PubMed

    Liu, Shuhui; Xie, Qilong; Chen, Jie; Sun, Janzhi; He, Hui; Zhang, Xiaoke

    2013-06-21

    In this study, two novel sample extraction methods for the analysis of bisphenol A (BPA) in edible oils were developed by using liquid-liquid extraction followed by a dispersive liquid-liquid microextraction (LLE-DLLME) and reversed-phase dispersive liquid-liquid microextraction (RP-DLLME). RP-DLLME showed a superior characteristic over LLE-DLLME and other previously reported procedures because of its easy operation, short extraction time, high sensitivity, low organic solvent consumption and waste generation. The optimized extraction conditions of RP-DLLME for 1.0 g of edible oil diluted in 4 mL of n-hexane were: extractant, 100 μL 0.2 M sodium hydroxide solution (80% methanol, v/v); extraction time, 1 min; centrifugation, 3 min. The determination of BPA was carried out by high performance liquid chromatography coupled with a DAD detector. The method offered excellent linearity over a range of 0.010-0.5 μg g(-1) with a correlation coefficient of r>0.997. Intra-day and inter-day repeatability values expressed as relative standard deviation were 1.9% and 5.9%, respectively. The quantitation limit and detection limit were 6.3 and 2.5 ng g(-1). The target analyte was detected in 5 out of 16 edible oil samples. The recovery rates in real samples ranged from 89.5 to 99.7%. PMID:23683892

  17. Dispersive Liquid-Liquid Microextraction Combined with Ultrahigh Performance Liquid Chromatography/Tandem Mass Spectrometry for Determination of Organophosphate Esters in Aqueous Samples

    PubMed Central

    Luo, Haiying; Xian, Yanping; Guo, Xindong; Luo, Donghui; Lu, Yujing; Yang, Bao

    2014-01-01

    A new technique was established to identify eight organophosphate esters (OPEs) in this work. It utilised dispersive liquid-liquid microextraction in combination with ultrahigh performance liquid chromatography/tandem mass spectrometry. The type and volume of extraction solvents, dispersion agent, and amount of NaCl were optimized. The target analytes were detected in the range of 1.0–200 µg/L with correlation coefficients ranging from 0.9982 to 0.9998, and the detection limits of the analytes were ranged from 0.02 to 0.07 µg/L (S/N = 3). The feasibility of this method was demonstrated by identifying OPEs in aqueous samples that exhibited spiked recoveries, which ranged between 48.7% and 58.3% for triethyl phosphate (TEP) as well as between 85.9% and 113% for the other OPEs. The precision was ranged from 3.2% to 9.3% (n = 6), and the interprecision was ranged from 2.6% to 12.3% (n = 5). Only 2 of the 12 selected samples were tested to be positive for OPEs, and the total concentrations of OPEs in them were 1.1 and 1.6 µg/L, respectively. This method was confirmed to be simple, fast, and accurate for identifying OPEs in aqueous samples. PMID:24616613

  18. Rapid determination of tetrabromobisphenol A and its main derivatives in aqueous samples by ultrasound-dispersive liquid-liquid microextraction combined with high-performance liquid chromatography.

    PubMed

    Wang, Xuemei; Liu, Jiyan; Liu, Qian; Du, Xinzhen; Jiang, Guibin

    2013-11-15

    A method of ultrasound-dispersive liquid-liquid microextraction (US-DLLME) combined with high-performance liquid chromatography/variable wavelength detection (HPLC-VWD) has been developed for rapid measuring tetrabromobisphenol A and its five derivatives in water. Parameters affecting the extraction efficiency including the extraction solvents and dispersive solvents and their volume, ionic strength of the sample, and ultrasound time were optimized, and further validated by orthogonal array design (OAD). The optimized conditions provided enrichment factors for analytes of 74-490. Most analytes had linear responses between 2 and 500 μg L(-1), with correlation coefficients (r(2)) of 0.9923-0.9994. Limits of detection were 0.13-0.63 μg L(-1). Relative standard deviations (RSDs) for five replicates ranged from 2.6% to 4.5% for all analytes. When applied to spiked samples of real water, the method provided recoveries of 88.6-106.3% for tap water, 87.8-108.5% for Mi River water, 82.7-113.5% for chemical wastewater, 45.5-115.3% for urine, and 46.4-126.2% for fruit juice, with RSDs (n=5) less than 4%, 6%, 8%, 10%, and 9% respectively. PMID:24148493

  19. Ionic-liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of multiclass pesticide residues in water samples.

    PubMed

    Tadesse, Bezuayehu; Teju, Endale; Gure, Abera; Megersa, Negussie

    2015-03-01

    Ionic-liquid-based dispersive liquid-liquid microextraction in combination with high-performance liquid chromatography and diode array detection has been proposed for the simultaneous analysis of four multiclass pesticide residues including carbaryl, methidathion, chlorothalonil, and ametryn from water samples. The major experimental parameters including the type and volume of ionic liquid, sample pH, type, and volume of disperser solvent and cooling time were investigated and optimum conditions were established. Under the optimum experimental conditions, limits of detection and quantification of the method were in the range of 0.1-1.8 and 0.4-5.9 μg/L, respectively, with satisfactory enrichment factors ranging from 10-20. The matrix-matched calibration curves, which were constructed for lake water, as a representative matrix were linear over wide range with coefficients of determination of 0.996 or better. Intra- and interday precisions, expressed as relative standard deviations, were in the range of 1.1-9.7 and 3.1-7.8%, respectively. The relative recoveries of the spiked environmental water samples at one concentration level were in the range of 77-102%. The results of the present study revealed that the proposed method is simple, fast, and uses environmentally friendly extraction solvent for the analysis of the target pesticide residues in environmental water samples. PMID:25641819

  20. Well-dispersed Pt cubes on porous Cu foam: high-performance catalysts for the electrochemical oxidation of glucose in neutral media.

    PubMed

    Niu, Xiangheng; Lan, Minbo; Zhao, Hongli; Chen, Chen

    2013-07-15

    The investigation of highly efficient catalysts for the electrochemical oxidation of glucose is the most critical challenge to commercialize nonenzymatic glucose sensors, which display a few attractive superiorities including the sufficient stability of their properties and the desired reproducibility of results over enzyme electrodes. Herein we propose a new and very promising catalyst: Pt cubes well-dispersed on the porous Cu foam, for the the electrochemical oxidation reaction of glucose in neutral media. The catalyst is fabricated in situ on a homemade screen-printed carbon electrode (SPCE) substrate through initially synthesizing the three-dimensional (3D) porous Cu foam using a hydrogen evolution assisted electrodeposition strategy, followed by electrochemically reducing the platinic precursor simply and conveniently. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) proofs demonstrate that Pt cubes, with an average size (the distance of opposite faces) of 185.1 nm, highly dispersed on the macro/nanopore integrated Cu foam support can be reproducibly obtained. The results of electrochemical tests indicate that the cubic Pt-based catalyst exhibits significant enhancement on the catalytic activity towards the electrooxidation of glucose in the presence of chloride ions, providing a specific activity 6.7 times and a mass activity 5.3 times those of commercial Pt/C catalysts at -0.4 V (vs. Ag/AgCl). In addition, the proposed catalyst shows excellent stability of performance, with only a 2.8% loss of electrocatalytic activity after 100 repetitive measurements. PMID:23744705

  1. Determination of eight fluoroquinolones in groundwater samples with ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction prior to high-performance liquid chromatography and fluorescence detection.

    PubMed

    Vázquez, M M Parrilla; Vázquez, P Parrilla; Galera, M Martínez; García, M D Gil

    2012-10-20

    An ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction (US-IL-DLLME) procedure was developed for the extraction of eight fluoroquinolones (marbofloxacin, norfloxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, oxolinic acid and nalidixic acid) in groundwater, using high-performance liquid chromatography with fluorescence detection (HPLC-FD). The ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution using a small volume of disperser solvent (0.4 mL of methanol), which increased the extraction efficiency and reduced the equilibrium time. For the DLLME procedure, the IL 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM] [PF(6)]) and methanol (MeOH) were used as extraction and disperser solvent, respectively. By comparing [C(8)MIM] [PF(6)] with 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM] [PF(6)]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)MIM] [PF(6)]) as extraction solvents, it was observed that when using [C(8)MIM] [PF(6)] the cloudy solution was formed more readily than when using [C(6)MIM] [PF(6)] or [C(4)MIM] [PF(6)]. The factors affecting the extraction efficiency, such as the type and volume of ionic liquid, type and volume of disperser solvent, cooling in ice-water, sonication time, centrifuging time, sample pH and ionic strength, were optimised. A slight increase in the recoveries of fluoroquinolones was observed when an ice-water bath extraction step was included in the analytical procedure (85-107%) compared to those obtained without this step (83-96%). Under the optimum conditions, linearity of the method was observed over the range 10-300 ng L(-1) with correlation coefficient >0.9981. The proposed method has been found to have excellent sensitivity with limit of detection between 0.8 and 13 ng L(-1) and precision with relative standard deviation values between 4.8 and 9.4% (RSD, n=5). Good enrichment factors (122-205) and recoveries (85

  2. Evaluation and Modification of Commercial Dry Powder Inhalers for the Aerosolization of a Submicrometer Excipient Enhanced Growth (EEG) Formulation

    PubMed Central

    Son, Yoen-Ju; Longest, P. Worth; Tian, Geng; Hindle, Michael

    2013-01-01

    The aim of this study was to evaluate and modify commercial dry powder inhalers (DPIs) for the aerosolization of a submicrometer excipient enhanced growth (EEG) formulation. The optimized device and formulation combination was then tested in a realistic in vitro mouth-throat - tracheobronchial (MT-TB) model. An optimized EEG submicrometer powder formulation, consisting of albuterol sulfate (drug), mannitol (hygroscopic excipient), L-leucine (dispersion enhancer) and poloxamer 188 (surfactant) in a ratio of 30:48:20:2 was prepared using a Büchi Nano spray dryer. The aerosolization performance of the EEG formulation was evaluated with 5 conventional DPIs: Aerolizer, Novolizer, HandiHaler, Exubera and Spiros. To improve powder dispersion, the HandiHaler was modified with novel mouth piece (MP) designs. The aerosol performance of each device was assessed using a next generation impactor (NGI) at airflow rates generating a pressure drop of 4 kPa across the DPI. In silico and in vitro deposition and hygroscopic growth of formulations was studied using a MT-TB airway geometry model. Both Handihaler and Aerolizer produced high emitted doses (ED) together with a significant submicrometer aerosol fraction. A modified HandiHaler with a MP including a three-dimensional (3D) array of rods (HH-3D) produced a submicrometer particle fraction of 38.8% with a conventional fine particle fraction (% <5µm) of 97.3%. The mass median diameter (MMD) of the aerosol was reduced below 1 µm using this HH-3D DPI. The aerosol generated from the modified HandiHaler increased to micrometer size (2.8 µm) suitable for pulmonary deposition, when exposed to simulated respiratory conditions, with negligible mouth-throat (MT) deposition (2.6 %). PMID:23608613

  3. Using the OMI aerosol index and absorption aerosol optical depth to evaluate the NASA MERRA Aerosol Reanalysis

    NASA Astrophysics Data System (ADS)

    Buchard, V.; da Silva, A. M.; Colarco, P. R.; Darmenov, A.; Randles, C. A.; Govindaraju, R.; Torres, O.; Campbell, J.; Spurr, R.

    2015-05-01

    . Finally, during a period where the Asian region was mainly dominated by anthropogenic aerosols, we have performed a qualitative analysis in which the specification of anthropogenic emissions in GEOS-5 is adjusted to provide insight into discrepancies observed in AI comparisons.

  4. Aerosol feed direct methanol fuel cell

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew (Inventor); Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor)

    2002-01-01

    Improvements to fuel cells include introduction of the fuel as an aerosol of liquid fuel droplets suspended in a gas. The particle size of the liquid fuel droplets may be controlled for optimal fuel cell performance by selection of different aerosol generators or by separating droplets based upon size using a particle size conditioner.

  5. Dispersion Modeling.

    ERIC Educational Resources Information Center

    Budiansky, Stephen

    1980-01-01

    This article discusses the need for more accurate and complete input data and field verification of the various models of air pollutant dispension. Consideration should be given to changing the form of air quality standards based on enhanced dispersion modeling techniques. (Author/RE)

  6. METHODS OF CALCULATINAG LUNG DELIVERY AND DEPOSITION OF AEROSOL PARTICLES

    EPA Science Inventory


    Lung deposition of aerosol is measured by a variety of methods. Total lung deposition can be measured by monitoring inhaled and exhaled aerosols in situ by laser photometry or by collecting the aerosols on filters. The measurements can be performed accurately for stable monod...

  7. Online determination of levoglucosan in ambient aerosols with Particle-into-Liquid Sampler - High-Performance Anion-Exchange Chromatography - Mass Spectrometry (PILS-HPAEC-MS)

    NASA Astrophysics Data System (ADS)

    Saarnio, K.; Teinilä, K.; Saarikoski, S.; Carbone, S.; Gilardoni, S.; Timonen, H.; Aurela, M.; Hillamo, R.

    2013-06-01

    Biomass burning, such as domestic heating, agricultural, and wild open-land fires, has a significant influence on the atmosphere at the global and, especially, at the local scale. Levoglucosan has been shown to be a good tracer for biomass burning emissions in atmospheric particulate matter and several analytical techniques have been presented for the determination of levoglucosan from filter samples. In this paper, a novel combination of a Particle-into-Liquid Sampler (PILS) to a high-performance anion-exchange chromatograph (HPAEC) with the detection by a mass spectrometer (MS) is presented for the online analysis of levoglucosan in ambient particles. The PILS-HPAEC-MS technique enables a fast online analysis of levoglucosan from the particulate samples. The method was tested at an urban background station in Helsinki, Finland, in winter 2011. A comparison with simultaneous levoglucosan measurements from filter samples by the HPAEC-MS was performed and it showed a good agreement between the online and offline methods. Additionally, the online levoglucosan data were compared with the biomass burning tracer fragments measured by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). As there were no local biomass burning sources close to the measurement station, online levoglucosan measurements revealed that most of the particles from biomass burning were either regionally distributed or long-range transported in the urban background of Helsinki. The average levoglucosan concentrations were relatively low (average 0.083 μg m-3) during the measurement campaign. The highest concentration peak measured for levoglucosan (1.4 μg m-3) seemed to originate from biomass burning in Eastern Europe, likely in Estonia, that was transported to Helsinki.

  8. Online determination of levoglucosan in ambient aerosols with particle-into-liquid sampler - high-performance anion-exchange chromatography - mass spectrometry (PILS-HPAEC-MS)

    NASA Astrophysics Data System (ADS)

    Saarnio, K.; Teinilä, K.; Saarikoski, S.; Carbone, S.; Gilardoni, S.; Timonen, H.; Aurela, M.; Hillamo, R.

    2013-10-01

    Biomass burning, such as domestic heating, agricultural, and wild open-land fires, has a significant influence on the atmosphere at the global and, especially, at the local scale. Levoglucosan has been shown to be a good tracer for biomass burning emissions in atmospheric particulate matter, and several analytical techniques have been presented for the determination of levoglucosan from filter samples. In this paper, a novel combination of a particle-into-liquid sampler (PILS) to a high-performance anion-exchange chromatograph (HPAEC) with the detection by a mass spectrometer (MS) is presented for the online analysis of levoglucosan in ambient particles. The PILS-HPAEC-MS technique enables a fast online analysis of levoglucosan from the particulate samples. The method was tested at an urban background station in Helsinki, Finland, in winter 2011. A comparison with simultaneous levoglucosan measurements from filter samples by the HPAEC-MS was performed and it showed a good agreement between the online and offline methods. Additionally, the online levoglucosan data were compared with the biomass burning tracer fragments measured by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). As there were no local biomass burning sources close to the measurement station, online levoglucosan measurements revealed that most of the particles from biomass burning were either regionally distributed or long-range transported in the urban background of Helsinki. The average levoglucosan concentrations were relatively low (average 0.083 μg m-3) during the measurement campaign. The highest concentration peak measured for levoglucosan (1.4 μg m-3) seemed to originate from biomass burning in the Baltic countries, likely in Estonia, that was transported to Helsinki.

  9. [Determination of amantadine and rimantadine residues in egg and chicken samples by dispersive solid phase extraction purification-ultra high performance liquid chromatography-tandem mass spectrometry].

    PubMed

    Lin, Tao; Fan, Jianlin; Liu, Xingyong; Chen, Xinglian; Li, Yangang; Liu, Hongcheng

    2015-11-01

    A method was developed for the determination of residual amantadine and rimantadine in eggs and chickens by dispersive solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry. Egg and chicken samples were extracted with ammonia water-acetonitrile (2:98, v/v). The extraction solution was dried to 1 mL under nitrogen, and then purified by dispersive solid phase extraction method with C18 and NH2 sorbents. After purification, the extraction solution was filtered through a filter. The target compounds were analyzed by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) on a ZORBAX C18 column using a mixture of 1 mmol/L ammonium acetate solution (containing 0.1% (v/v) formic acid) and methanol as mobile phases with gradient elution. The mass spectrometer was operated under multiple reaction monitoring (MRM) mode in positive mode. The good linearities were obtained for amantadine and rimantadine at a concentration range of 0.15-10.0 μg/L. The limits of detection for amantadine and rimantadine were all 0.05 μg/kg, and the limits of quantification were 0.20 μg/kg. The recoveries of amantadine and rimantadine in eggs and chickens at three spiked levels (0.2, 1.0 and 2.0 μg/kg) age of 89%-108% with the relative standard deviations of 5.0%-8.6%. The results demonstrated that the method is suitable for the determination of amantadine and rimantadine in eggs and chickens. PMID:26939363

  10. Global Atmospheric Aerosol Modeling

    NASA Technical Reports Server (NTRS)

    Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

    2012-01-01

    Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

  11. A review of dispersion modelling and its application to the dispersion of particles: An overview of different dispersion models available

    NASA Astrophysics Data System (ADS)

    Holmes, N. S.; Morawska, L.

    This paper provides the first review of the application of atmospheric models for particle dispersion. The different types of dispersion models available, from simple box type models to complex fluid dynamics models are outlined and the suitability of the different approaches to dispersion modelling within different environments, in regards to scale, complexity of the environment and concentration parameters is assessed. Finally, several major commercial and non-commercial particle dispersion packages are reviewed, detailing which processes are included and advantages and limitations of their use to modelling particle dispersion. The models reviewed included: Box models (AURORA, CPB and PBM), Gaussian models (CALINE4, HIWAY2, CAR-FMI, OSPM, CALPUFF, AEROPOL, AERMOD, UK-ADMS and SCREEN3), Lagrangian/Eulerian Models (GRAL, TAPM, ARIA Regional), CFD models (ARIA Local, MISKAM, MICRO-CALGRID) and models which include aerosol dynamics (GATOR, MONO32, UHMA, CIT, AERO, RPM, AEROFOR2, URM-1ATM, MADRID, CALGRID and UNI-AERO).

  12. Aerosol gels

    NASA Technical Reports Server (NTRS)

    Sorensen, Christopher M. (Inventor); Chakrabarti, Amitabha (Inventor); Dhaubhadel, Rajan (Inventor); Gerving, Corey (Inventor)

    2010-01-01

    An improved process for the production of ultralow density, high specific surface area gel products is provided which comprises providing, in an enclosed chamber, a mixture made up of small particles of material suspended in gas; the particles are then caused to aggregate in the chamber to form ramified fractal aggregate gels. The particles should have a radius (a) of up to about 50 nm and the aerosol should have a volume fraction (f.sub.v) of at least 10.sup.-4. In preferred practice, the mixture is created by a spark-induced explosion of a precursor material (e.g., a hydrocarbon) and oxygen within the chamber. New compositions of matter are disclosed having densities below 3.0 mg/cc.

  13. On performance of parametric and distribution-free models for zero-inflated and over-dispersed count responses.

    PubMed

    Tang, Wan; Lu, Naiji; Chen, Tian; Wang, Wenjuan; Gunzler, Douglas David; Han, Yu; Tu, Xin M

    2015-10-30

    Zero-inflated Poisson (ZIP) and negative binomial (ZINB) models are widely used to model zero-inflated count responses. These models extend the Poisson and negative binomial (NB) to address excessive zeros in the count response. By adding a degenerate distribution centered at 0 and interpreting it as describing a non-risk group in the population, the ZIP (ZINB) models a two-component population mixture. As in applications of Poisson and NB, the key difference between ZIP and ZINB is the allowance for overdispersion by the ZINB in its NB component in modeling the count response for the at-risk group. Overdispersion arising in practice too often does not follow the NB, and applications of ZINB to such data yield invalid inference. If sources of overdispersion are known, other parametric models may be used to directly model the overdispersion. Such models too are subject to assumed distributions. Further, this approach may not be applicable if information about the sources of overdispersion is unavailable. In this paper, we propose a distribution-free alternative and compare its performance with these popular parametric models as well as a moment-based approach proposed by Yu et al. [Statistics in Medicine 2013; 32: 2390-2405]. Like the generalized estimating equations, the proposed approach requires no elaborate distribution assumptions. Compared with the approach of Yu et al., it is more robust to overdispersed zero-inflated responses. We illustrate our approach with both simulated and real study data. PMID:26078035

  14. Fog dispersion

    NASA Technical Reports Server (NTRS)

    Frost, W.; Christensen, L. S.; Collins, F. G.; Camp, D. W.

    1980-01-01

    A study of economically viable techniques for dispersing warm fog at commercial airports is presented. Five fog dispersion techniques are examined: evaporation suppression, downwash, mixing, seeding with hygroscopic material, thermal techniques, and charged particle techniques. Thermal techniques, although effective, were found to be too expensive for routine airport operations, and detrimental to the environment. Seeding or helicopter downwash are practical for small-scale or temporary fog clearing, but are probably not useful for airport operations on a routine basis. Considerable disagreement exists on the capability of charged particle techniques, which stems from the fact that different assumptions and parameter values are used in the analytical models. Recommendations resulting from the review of this technique are listed, and include: experimental measurements of the parameters in question; a study to ascertain possible safety hazards, such as increased electrical activity or fuel ignition during refueling operations which could render charged particle techniques impractical; and a study of a single charged particle generator.

  15. Aerosol volatility in a boreal forest environment

    NASA Astrophysics Data System (ADS)

    Häkkinen, S. A. K.; ńijälä, M.; Lehtipalo, K.; Junninen, H.; Virkkula, A.; Worsnop, D. R.; Kulmala, M.; Petäjä, T.; Riipinen, I.

    2012-04-01

    Climate and health effects of atmospheric aerosols are determined by their properties such as their chemical composition. Aerosol chemical composition can be studied indirectly by measuring volatility of aerosol particles. The volatility of submicron aerosol particles (20-500 nm) was studied in a boreal forest site at SMEAR II (Station for Measuring Ecosystem-Atmosphere Relations II) station (Vesala et al., 1998) in Hyytiälä, Finland, during 01/2008-05/2010. The instrument used for the measurements was VDMPS (Volatility Differential Mobility Particle Sizer), which consists of two separate instruments: DMPS (Differential Mobility Particle Sizer, Aalto et al., 2001) and TD (Thermodenuder, Wehner et al., 2002). Aerosol evaporation was examined by heating the aerosol and comparing the total aerosol mass before and after heating. In the VDMPS system ambient aerosol sample was heated up to temperatures ranging from 80 °C to 280 °C. The higher the heating temperature was the more aerosol material was evaporated. There was a non-volatile residual present in aerosol particles when heated up to 280 °C. This residual explained (20±8)% of the total aerosol mass. Aerosol non-volatile mass fraction was highest during winter and smallest during summer months. The role of black carbon in the observed non-volatile residual was determined. Black carbon explained 40 to 90% of the non-volatile mass. Especially during colder seasons noticeable amount of non-volatile material, something else than black carbon, was observed. According to Kalberer et al. (2004) some atmospheric organic species can form polymers that have high evaporation temperatures. Also low-volatile organic salts may contribute to the non-volatile aerosol (Smith et al., 2010). Aerosol mass composition measured directly with AMS (Aerosol Mass Spectrometer, Jayne et al., 2000) was analyzed in order to examine the properties of the non-volatile material (other than black carbon). The AMS measurements were performed

  16. A COMPUTER-CONTROLLED WHOLE-BODY INHALATION EXPOSURE SYSTEM FOR THE OIL DISPERSANT COREXIT EC9500A

    PubMed Central

    Goldsmith, William Travis; McKinney, Walter; Jackson, Mark; Law, Brandon; Bledsoe, Toni; Siegel, Paul; Cumpston, Jared; Frazer, David

    2015-01-01

    An automated whole-body inhalation exposure system capable of exposing 12 individually housed rats was designed to examine the potential adverse health effects of the oil dispersant COREXIT EC9500A, used extensively during the Deepwater Horizon oil spill. A computer–controlled syringe pump injected the COREXIT EC9500A into an atomizer where droplets and vapor were formed and mixed with diluent air. The aerosolized COREXIT EC9500A was passed into a customized exposure chamber where a calibrated light-scattering instrument estimated the real-time particle mass concentration of the aerosol in the chamber. Software feedback loops controlled the chamber aerosol concentration and pressure throughout each exposure. The particle size distribution of the dispersant aerosol was measured and shown to have a count median aerodynamic diameter of 285 nm with a geometric standard deviation of 1.7. The total chamber concentration (particulate + vapor) was determined using a modification of the acidified methylene blue spectrophotometric assay for anionic surfactants. Tests were conducted to show the effectiveness of closed loop control of chamber concentration and to verify chamber concentration homogeneity. Five automated 5-h animal exposures were performed that produced controlled and consistent COREXIT EC9500A concentrations (27.1 ± 2.9 mg/m3, mean ± SD). PMID:21916743

  17. Elution strategies for reversed-phase high-performance liquid chromatography analysis of sucrose alkanoate regioisomers with charged aerosol detection.

    PubMed

    Lie, Aleksander; Pedersen, Lars Haastrup

    2013-10-11

    A broad range of elution strategies for RP-HPLC analysis of sucrose alkanoate regioisomers with CAD was systematically evaluated. The HPLC analyses were investigated using design-of-experiments methodology and analysed by analysis of variance (ANOVA) and regression modelling. Isocratic elutions, isocratic elutions with increased flow, and gradient elutions with step-down profiles and step-up profiles were performed and the chromatographic parameters of the different elution strategies were described by suitable variables. Based on peak resolutions general resolution deviation for multiple peaks (RDm) was developed for sample-independent evaluation of separation of any number of peaks in chromatographic analysis. Isocratic elutions of sucrose alkanoates showed similar relationships between eluent acetonitrile concentration and retention time for all regioisomers of sucrose caprate and sucrose laurate, as confirmed by evaluation of the curvatures using approximate second derivatives and Kendall rank correlation coefficients. Regression modelling and statistical analysis showed that acetonitrile concentration and flow rate were highly significant for both average adjusted retention time and RDm for sucrose laurate. For both responses the effect of changes in acetonitrile concentration was larger than the effect of changes in flow rate, over the ranges studied. Regression modelling of the step-down gradient profiles for the sucrose alkanoates showed that the eluent acetonitrile concentrations were the overall most significant variables for retention time and separation. The models for average adjusted retention time of sucrose caprate and sucrose laurate showed only a few differences in the significance levels of terms, while the models for RDm showed larger differences between the sucrose alkanoates, in both the number of terms and their significance. Efficiency evaluation of elution strategies, in terms of RDm and analysis time, showed that the best results were

  18. Aerosol optical properties at a coastal site in Hong Kong, South China: temporal features, size dependencies and source analysis

    NASA Astrophysics Data System (ADS)

    Wang, Jiaping; Ding, Aijun; Virkkula, Aki; Lee, Shuncheng; Shen, Yicheng; Chi, Xuguang; Xu, Zheng

    2016-04-01

    Hong Kong is a typical coastal city adjacent to the Pearl River Delta (PRD) region in southern China, which is one of the regions suffering from severe air pollution. Atmospheric aerosols can affect the earth's radiative balance by scattering and absorbing incoming solar radiation. Black Carbon (BC) aerosol is a particularly emphasized component due to its strong light absorption. Aerosol transported from different source areas consists of distinct size distributions, leading to different optical properties. As the byproducts of the incomplete oxidation, BC and CO both have relatively long life time, their relationship is a good indicator for distinguishing different pollutant sources. In this study, temporal variations of aerosol optical properties and concentrations of BC and CO at a coastal background station in Hong Kong were investigated. Transport characteristics and origins of aerosol were elucidated by analyzing backward Lagrangian particle dispersion modeling (LPDM) results, together with related parameters including the relationships between optical properties and particle size, BC-CO correlations, ship location data and meteorological variables. From February 2012 to September 2013 and March 2014 to February 2015, continuous in-situ measurements of light scattering and absorption coefficients, particle size distribution and concentrations of BC and CO were conducted at Hok Tsui (HT), a coastal background station on the southeast tip of Hong Kong Island (22.22°N, 114.25°E, 60 m above the sea level) with few local anthropogenic activities. Affected by the Asian monsoon, this region is dominated by continental outflow in winter and by marine inflow from the South China Sea in summer, which is an ideal station for identifying the transport characteristics of aerosol and their effects on optical properties from different anthropogenic emission sources. 7-day backward Lagrangian particle dispersion modeling was performed for source identification. Three

  19. Spent fuel sabotage aerosol test program :FY 2005-06 testing and aerosol data summary.

    SciTech Connect

    Gregson, Michael Warren; Brockmann, John E.; Nolte, O. (Fraunhofer institut fur toxikologie und experimentelle Medizin, Germany); Loiseau, O. (Institut de radioprotection et de Surete Nucleaire, France); Koch, W. (Fraunhofer institut fur toxikologie und experimentelle Medizin, Germany); Molecke, Martin Alan; Autrusson, Bruno (Institut de radioprotection et de Surete Nucleaire, France); Pretzsch, Gunter Guido (Gesellschaft fur anlagen- und Reaktorsicherheit, Germany); Billone, M. C. (Argonne National Laboratory, USA); Lucero, Daniel A.; Burtseva, T.; Brucher, W (Gesellschaft fur anlagen- und Reaktorsicherheit, Germany); Steyskal, Michele D.

    2006-10-01

    This multinational, multi-phase spent fuel sabotage test program is quantifying the aerosol particles produced when the products of a high energy density device (HEDD) interact with and explosively particulate test rodlets that contain pellets of either surrogate materials or actual spent fuel. This program has been underway for several years. This program provides source-term data that are relevant to some sabotage scenarios in relation to spent fuel transport and storage casks, and associated risk assessments. This document focuses on an updated description of the test program and test components for all work and plans made, or revised, primarily during FY 2005 and about the first two-thirds of FY 2006. It also serves as a program status report as of the end of May 2006. We provide details on the significant findings on aerosol results and observations from the recently completed Phase 2 surrogate material tests using cerium oxide ceramic pellets in test rodlets plus non-radioactive fission product dopants. Results include: respirable fractions produced; amounts, nuclide content, and produced particle size distributions and morphology; status on determination of the spent fuel ratio, SFR (the ratio of respirable particles from real spent fuel/respirables from surrogate spent fuel, measured under closely matched test conditions, in a contained test chamber); and, measurements of enhanced volatile fission product species sorption onto respirable particles. We discuss progress and results for the first three, recently performed Phase 3 tests using depleted uranium oxide, DUO{sub 2}, test rodlets. We will also review the status of preparations and the final Phase 4 tests in this program, using short rodlets containing actual spent fuel from U.S. PWR reactors, with both high- and lower-burnup fuel. These data plus testing results and design are tailored to support and guide, follow-on computer modeling of aerosol dispersal hazards and radiological consequence

  20. Performance of a focused cavity aerosol spectrometer for measurements in the stratosphere of particle size in the 0.06-2.0-micrometer-diameter range

    NASA Technical Reports Server (NTRS)

    Jonsson, H. H.; Wilson, J. C.; Brock, C. A.; Knollenberg, R. G.; Newton, R.; Dye, J. E.; Baumgardner, D.; Borrmann, S.; Ferry, G. V.; Pueschel, R.

    1995-01-01

    A focused cavity aerosol spectrometer aboard a NASA ER-2 high-altitude aircraft provided high-resolution measurements of the size of the stratospheric particles in the 0.06-2.0-micrometer-diameter range in flights following the eruption of Mount Pinatubo in 1991. Effects of anisokinetic sampling and evaporation in the sampling system were accounted for by means adapted and specifically developed for this instrument. Calibrations with monodisperse aerosol particles provided the instrument's response matrix, which upon inversion during data reduction yielded the particle size distributions. The resultant dataset is internally consistent and generally shows agreement to within a factor of 2 with comparable measurements simultaneously obtained by a condensation nuclei counter, a forward-scattering spectrometer probe, and aerosol particle impactors, as well as with nearby extinction profiles obtained by satellite measurements and with lidar measurements of backscatter.

  1. Aerosol typing - key information from aerosol studies

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Kahn, Ralph; Papagiannopoulos, Nikolaos; Holzer-Popp, Thomas; Pappalardo, Gelsomina

    2016-04-01

    Aerosol typing is a key source of aerosol information from ground-based and satellite-borne instruments. Depending on the specific measurement technique, aerosol typing can be used as input for retrievals or represents an output for other applications. Typically aerosol retrievals require some a priori or external aerosol type information. The accuracy of the derived aerosol products strongly depends on the reliability of these assumptions. Different sensors can make use of different aerosol type inputs. A critical review and harmonization of these procedures could significantly reduce related uncertainties. On the other hand, satellite measurements in recent years are providing valuable information about the global distribution of aerosol types, showing for example the main source regions and typical transport paths. Climatological studies of aerosol load at global and regional scales often rely on inferred aerosol type. There is still a high degree of inhomogeneity among satellite aerosol typing schemes, which makes the use different sensor datasets in a consistent way difficult. Knowledge of the 4d aerosol type distribution at these scales is essential for understanding the impact of different aerosol sources on climate, precipitation and air quality. All this information is needed for planning upcoming aerosol emissions policies. The exchange of expertise and the communication among satellite and ground-based measurement communities is fundamental for improving long-term dataset consistency, and for reducing aerosol type distribution uncertainties. Aerosol typing has been recognized as one of its high-priority activities of the AEROSAT (International Satellite Aerosol Science Network, http://aero-sat.org/) initiative. In the AEROSAT framework, a first critical review of aerosol typing procedures has been carried out. The review underlines the high heterogeneity in many aspects: approach, nomenclature, assumed number of components and parameters used for the

  2. Performance of McRAS-AC in the GEOS-5 AGCM: Part 1, Aerosol-Activated Cloud Microphysics, Precipitation, Radiative Effects, and Circulation

    NASA Technical Reports Server (NTRS)

    Sud, Y. C.; Lee, D.; Oreopoulos, L.; Barahona, D.; Nenes, A.; Suarez, M. J.

    2012-01-01

    A revised version of the Microphysics of clouds with Relaxed Arakawa-Schubert and Aerosol-Cloud interaction (McRAS-AC), including, among others, the Barahona and Nenes ice nucleation parameterization, is implemented in the GEOS-5 AGCM. Various fields from a 10-year long integration of the AGCM with McRAS-AC were compared with their counterparts from an integration of the baseline GEOS-5 AGCM, and with satellite data as observations. Generally using McRAS-AC reduced biases in cloud fields and cloud radiative effects are much better over most of the regions of the Earth. Two weaknesses are identified in the McRAS-AC runs, namely, too few cloud particles around 40S-60S, and too high cloud water path during northern hemisphere summer over the Gulf Stream and North Pacific. Sensitivity analyses showed that these biases potentially originated from biases in the aerosol input. The first bias is largely eliminated in a sensitivity test using 50% smaller aerosol particles, while the second bias is much reduced when interactive aerosol chemistry was turned on. The main drawback of McRAS-AC is dearth of low-level marine stratus clouds, probably due to lack of dry-convection, not yet implemented into the cloud scheme. Despite these biases, McRAS-AC does simulate realistic clouds and their optical properties that can improve with better aerosol-input and thereby has the potential to be a valuable tool for climate modeling research because of its aerosol indirect effect simulation capabilities involving prediction of cloud particle number concentration and effective particle size for both convective and stratiform clouds is quite realistic.

  3. Determination of some B Vitamins in Sour Cherry Juice Using Dispersive Liquid-liquid Microextraction Followed by High-performance Liquid Chromatography

    PubMed Central

    Parsaei, Parvin; Bahmaei, Manouchehr; Ghannadi, AliReza

    2014-01-01

    Dispersive liquid-liquid microextraction method (DLLME) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine thiamine (B1), nicotinamide (B3) and pyridoxine (B6) in sour cherry juice. This method was rapid, simple and sensitive. Separation was accomplished using a C18 column. The optimum chromatographic conditions were found to be: mobile phase consisted of 8% methanol and 92% aqueous phase (1% (V/V) acetic acid water solution); flow rate, 0.7 mL/min; detection wavelength, 260 nm and pH, 3.3. The extraction efficiency of thiamine, nicotinamide and pyridoxine was influenced by factors such as: additional salt effect, the kind and volume of disperser and extraction solvents. In this research, the limit of detection (LOD) and quantification (LOQ) were 0.9 and 3 ng/mL for thiamine, 1.5 and 5 ng/mL for nicotinamide, 0.9 and 3 ng/mL for pyridoxine. The relative standard deviations (RSDs) were less than 2.87% (n=3). An appropriate linear behavior over the observed concentration range was obtained with the value of R²>0.996 for the target vitamins. This method was successfully applied to the sour cherry juice samples. Sour cherry var. Gise (Prunus cerasus var. Gise), which was used in this research, was a local variety of the sour cherry with large stone, double flowers, double fruits, dark red skin and dark red juice. This variety was identified in high altitude areas of Isfahan province after five years of study, since 2005, by Agricultural and Natural Resources Research Center of Isfahan. PMID:25587335

  4. Determination of some B Vitamins in Sour Cherry Juice Using Dispersive Liquid-liquid Microextraction Followed by High-performance Liquid Chromatography.

    PubMed

    Parsaei, Parvin; Bahmaei, Manouchehr; Ghannadi, AliReza

    2014-01-01

    Dispersive liquid-liquid microextraction method (DLLME) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine thiamine (B1), nicotinamide (B3) and pyridoxine (B6) in sour cherry juice. This method was rapid, simple and sensitive. Separation was accomplished using a C18 column. The optimum chromatographic conditions were found to be: mobile phase consisted of 8% methanol and 92% aqueous phase (1% (V/V) acetic acid water solution); flow rate, 0.7 mL/min; detection wavelength, 260 nm and pH, 3.3. The extraction efficiency of thiamine, nicotinamide and pyridoxine was influenced by factors such as: additional salt effect, the kind and volume of disperser and extraction solvents. In this research, the limit of detection (LOD) and quantification (LOQ) were 0.9 and 3 ng/mL for thiamine, 1.5 and 5 ng/mL for nicotinamide, 0.9 and 3 ng/mL for pyridoxine. The relative standard deviations (RSDs) were less than 2.87% (n=3). An appropriate linear behavior over the observed concentration range was obtained with the value of R²>0.996 for the target vitamins. This method was successfully applied to the sour cherry juice samples. Sour cherry var. Gise (Prunus cerasus var. Gise), which was used in this research, was a local variety of the sour cherry with large stone, double flowers, double fruits, dark red skin and dark red juice. This variety was identified in high altitude areas of Isfahan province after five years of study, since 2005, by Agricultural and Natural Resources Research Center of Isfahan. PMID:25587335

  5. TEM Study of SAFARI-2000 Aerosols

    NASA Technical Reports Server (NTRS)

    Buseck, Peter R.

    2004-01-01

    The aim of our research was to obtain data on the chemical and physical properties of individual aerosol particles from biomass smoke plume s in southern Africa and from air masses in the region that are affec ted by the smoke. We used analytical transmission electron microscopy (ATEM), including energy-dispersive X-ray spectrometry (EDS) and ele ctron energy-loss spectroscopy (EELS), and field-emission electron microscopy (FESEM) to study aerosol particles from several smoke and haz e samples and from a set of cloud samples.

  6. Dispersion analysis for baseline reference mission 2

    NASA Technical Reports Server (NTRS)

    Snow, L. S.

    1975-01-01

    A dispersion analysis considering uncertainties (or perturbations) in platform, vehicle, and environmental parameters was performed for baseline reference mission (BRM) 2. The dispersion analysis is based on the nominal trajectory for BRM 2. The analysis was performed to determine state vector and performance dispersions (or variations) which result from the indicated uncertainties. The dispersions are determined at major mission events and fixed times from liftoff (time slices). The dispersion results will be used to evaluate the capability of the vehicle to perform the mission within a specified level of confidence and to determine flight performance reserves.

  7. Pulmonary Deposition of Aerosols in Microgravity

    NASA Technical Reports Server (NTRS)

    Prisk, G. Kim

    1997-01-01

    The intrapulmonary deposition of airborne particles (aerosol) in the size range of 0.5 to 5 microns is primarily due to gravitational sedimentation. In the microgravity (muG) environment, sedimentation is no longer active, and thus there should be marked changes in the amount and site of the deposition of these aerosol. We propose to study the total intrapulmonary deposition of aerosol spanning the range 0.5 to 5 microns in the KC-135 at both muG and at 1.8-G. This will be followed by using boli of 1.0 micron aerosol, inhaled at different points in a breath to study aerosol dispersion and deposition as a function of inspired depth. The results of these studies will have application in better understanding of pulmonary diseases related to inhaled particles (pneumoconioses), in studying drugs delivered by inhalation, and in understanding the consequence of long-term exposure to respirable aerosols in long-duration space flight.

  8. Molecularly Imprinted Dispersive Solid-Phase Extraction for the Determination of Triazine Herbicides in Grape Seeds by High-Performance Liquid Chromatography.

    PubMed

    Li, Xinpei; Wang, Yuanpeng; Sun, Qun; Xu, Bo; Yang, Zhaoqing; Wang, Xinghua

    2016-05-01

    Molecular imprinting technique, regarded as one of the current state-of-the-art researches, was incorporated with the simple dispersive solid-phase extraction (MI-DSPE) in this work for the extraction of triazine herbicides in grape seeds. The atrazine molecularly imprinted polymers (MIPs) were successfully prepared and characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The imprinting particles were used as the adsorbent in DSPE. Thus, a simple, rapid and selective method based on MIPs coupled with DSPE was established for the simultaneous cleaning-up and quantitative extraction of four triazine herbicides in grape seeds. The experiment parameters, including type of washing solvents, washing time and type of eluting solvents, were investigated and optimized. The performance of the present method was validated by high-performance liquid chromatography. Good linear responses were obtained in concentration range of 0.010-5.0 µg g(-1)with correlation coefficients (r(2)) higher than 0.9993. The recoveries at two spiked levels (1.0 and 2.0 µg g(-1)) were between 81.2 and 113.0% with relative deviations ranging from 1.2 to 10.7%. The limits of detection were ranged between 0.006 and 0.013 µg g(-1), which were lower than the values required by European regulations. PMID:27013667

  9. Applying the data fusion method to evaluation of the performance of two control signals in monitoring polarization mode dispersion effects in fiber optic links

    NASA Astrophysics Data System (ADS)

    Dashtbani Moghari, M.; Rezaei, P.; Habibalahi, A.

    2015-02-01

    With increasing distance and bit rate in fiber optic links the effects of polarization mode dispersion (PMD) have been highlighted. Since PMD has a statistical nature, using a control signal that can provide accurate information to dynamically tune a PMD compensator is of great importance. In this paper, we apply the data fusion method with the aim of introducing a method that can be used to evaluate more accurately the performance of control signals before applying them in a PMD compensation system. Firstly, the minimum and average degree of polarization (DOP_min and DOP_ave respectively) as control signals in monitoring differential group delay (DGD) for a system including all-order PMD are calculated. Then, features including the amounts of sensitivity and ambiguity in DGD monitoring are calculated for NRZ data format as DGD to bit time (DGD/T) varies. It is shown that each of the control signals mentioned has both positive and negative features for efficient DGD monitoring. Therefore, in order to evaluate features concurrently and increase reliability, we employ data fusion to fuse features of each control signal, which makes evaluating and predicting the performance of control signals possible, before applying them in a real PMD compensation system. Finally, the reliability of the results obtained from data fusion is tested in a typical PMD compensator.

  10. Pipette vial dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice.

    PubMed

    Xi, Xuefei; Yang, Miyi; Shen, Ganni; Wu, Xiaoling; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2016-01-01

    A simple, sensitive, and efficient method of using a pipette vial to perform dispersive liquid-liquid microextraction based on the solidification of floating organic droplets was coupled with high-performance liquid chromatography (HPLC) and a diode array detector for the preconcentration and analysis of four benzoylurea insecticides in fruit juice. In this method, 1-dodecanol was used as an extractant, and a snipped pipette was used as an experimental vial to simplify the procedure of collecting and separating solidified extractant. The experimental parameters were optimized using a Plackett-Burman design and one-factor-at-a-time method. Under the optimal conditions in the water model, the limits of detection for analytes varied from 0.03 to 0.28 μg/L, and the enrichment factors ranged from 147 to 206. Linearity was achieved for diflubenzuron and flufenoxuron in a range of 0.5-500 μg/L, for hexaflumuron in a range of 1-500 μg/L, and for triflumuron in a range of 5-500 μg/L. The correlation coefficients for the analytes ranged from 0.9986 to 0.9994 with recoveries of 91.4-110.9%. Finally, the developed technique was successfully applied to fruit juice samples with acceptable results. The relative standard deviations of the analytes at two spiking levels (50 and 200 μg/L) varied between 0.2 and 4.5%. PMID:26526571

  11. Trace analysis of some organophosphorus pesticides in rice samples using ultrasound-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    PubMed

    Sharafi, Kiomars; Fattahi, Nazir; Mahvi, Amir Hossein; Pirsaheb, Meghdad; Azizzadeh, Nahid; Noori, Masomeh

    2015-03-01

    An ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of a floating organic drop method followed by high-performance liquid chromatography was developed for the extraction, preconcentration, and determination of trace amounts of organophosphorus pesticides in rice samples. Variables affecting the performance of both steps were thoroughly investigated. Some effective parameters on extraction were studied and optimized. Under the optimum conditions, recoveries for rice sample are in the range of 58.0-66.0%. The calibration graphs are linear in the range of 4-800 μg/kg and, limits of detection and limits of quantification are in the range of 1.5-3 and 4.2-8.5 μg/kg, respectively. The relative standard deviation for 50.0 μg/kg of organophosphorus pesticides in rice sample are in the range of 4.4-5.1% (n = 5). The obtained results show that proposed method is a fast and simple method for the determination of pesticides in cereals. PMID:25641828

  12. Preconcentration and determination of chlordiazepoxide and diazepam drugs using dispersive nanomaterial-ultrasound assisted microextraction method followed by high performance liquid chromatography.

    PubMed

    Pebdani, A Amiri; Khodadoust, S; Talebianpoor, M S; Zargar, H R; Zarezade, V

    2016-01-01

    Benzodiazepines (BDs) are used widely in clinical practice, due to their multiple pharmacological functions. In this study a dispersive nanomaterial-ultrasound assisted- microextraction (DNUM) method followed by high performance liquid chromatography (HPLC) was used for the preconcentration and determination of chlordiazepoxide and diazepam drugs from urine and plasma samples. Various parameters such as amount of adsorbent (mg: ZnS-AC), pH and ionic strength of sample solution, vortex and ultrasonic time (min), and desorption volume (mL) were investigated by fractional factorial design (FFD) and central composite design (CCD). Regression models and desirability functions (DF) were applied to find the best experimental conditions for providing the maximum extraction recovery (ER). Under the optimal conditions a linear calibration curve were obtained in the range of 0.005-10μgmL(-1) and 0.006-10μgmL(-1) for chlordiazepoxide and diazepam, respectively. To demonstrate the analytical performance, figures of merits of the proposed method in urine and plasma spiked with chlordiazepoxide and diazepam were investigated. The limits of detection of chlordiazepoxide and diazepam in urine and plasma were ranged from 0.0012 to 0.0015μgmL(-1), respectively. PMID:26655106

  13. Determination of Triazine Herbicides in Drinking Water by Dispersive Micro Solid Phase Extraction with Ultrahigh-Performance Liquid Chromatography-High-Resolution Mass Spectrometric Detection.

    PubMed

    Chen, Dawei; Zhang, Yiping; Miao, Hong; Zhao, Yunfeng; Wu, Yongning

    2015-11-11

    A novel dispersive micro solid phase extraction (DMSPE) method based on a polymer cation exchange material (PCX) was applied to the simultaneous determination of the 30 triazine herbicides in drinking water with ultrahigh-performance liquid chromatography-high-resolution mass spectrometric detection. Drinking water samples were acidified with formic acid, and then triazines were adsorbed by the PCX sorbent. Subsequently, the analytes were eluted with ammonium hydroxide/acetonitrile. The chromatographic separation was performed on an HSS T3 column using water (4 mM ammonium formate and 0.1% formic acid) and acetonitrile (0.1% formic acid) as the mobile phase. The method achieved LODs of 0.2-30.0 ng/L for the 30 triazines, with recoveries in the range of 70.5-112.1%, and the precision of the method was better than 12.7%. These results indicated that the proposed method had the advantages of convenience and high efficiency when applied to the analysis of the 30 triazines in drinking water. PMID:26487365

  14. Dispersion and Filtration of Carbon Nanotubes (CNTs) and Measurement of Nanoparticle Agglomerates in Diesel Exhaust

    PubMed Central

    Wang, Jing; Pui, David Y.H.

    2012-01-01

    Carbon nanotubes (CNTs) tend to form bundles due to their geometry and van der Walls forces, which usually complicates studies of the CNT properties. Dispersion plays a significant role in CNT studies and we summarize dispersion techniques to generate airborne CNTs from suspensions or powders. We describe in detail our technique of CNT aerosolization with controlled degree of agglomeration using an electrospray system. The results of animal inhalation studies using the electrosprayed CNTs are presented. We have performed filtration experiments for CNTs through a screen filter. A numerical model has been established to simulate the CNT filtration experiments. Both the modeling and experimental results show that the CNT penetration is less than the penetration for a sphere with the same mobility diameter, which is mainly due to the larger interception length of the CNTs. There is a need for instruments capable of fast and online measurement of gas-borne nanoparticle agglomerates. We developed an instrument Universal NanoParticle Analyzer (UNPA) and the measurement results for diesel exhaust particulates are presented. The results presented here are pertinent to non-spherical aerosol particles, and illustrate the effects of particle morphology on aerosol behaviors. PMID:23355749

  15. Statistical description of turbulent dispersion

    NASA Astrophysics Data System (ADS)

    Brouwers, J. J. H.

    2012-12-01

    We derive a comprehensive statistical model for dispersion of passive or almost passive admixture particles such as fine particulate matter, aerosols, smoke, and fumes in turbulent flow. The model rests on the Markov limit for particle velocity. It is in accordance with the asymptotic structure of turbulence at large Reynolds number as described by Kolmogorov. The model consists of Langevin and diffusion equations in which the damping and diffusivity are expressed by expansions in powers of the reciprocal Kolmogorov constant C0. We derive solutions of O(C00) and O(C0-1). We truncate at O(C0-2) which is shown to result in an error of a few percentages in predicted dispersion statistics for representative cases of turbulent flow. We reveal analogies and remarkable differences between the solutions of classical statistical mechanics and those of statistical turbulence.

  16. Investigations of the surface functionalization of titania: Dispersion-induced effects within mixed monolayers, linker-assisted assembly of quantum dots, and photovoltaic device performance

    NASA Astrophysics Data System (ADS)

    Kern, Meghan Elizabeth

    The research presented in this dissertation focuses on the surface chemistry of nanomaterials, specifically the study of the parameters influencing the surface functionalization of nanocrystalline TiO2 thin films with adsorbates and CdSe quantum dots (QDs) and their influence on the photovoltaic device performance of quantum dot-sensitized solar cells (QDSSCs). Mixed monolayers will be the subject of discussion for the first half of this dissertation and the remaining portion will focus on the discussion of materials assembly. Lateral dispersion forces induce the ordering of n-alkanoic acids on nanocrystalline TiO2 films and cause the compositions of mixed monolayers to change. The equilibrium formation of singlecomponent monolayers of n-alkanoic acids and 6-bromohexanoic acid (Br6A) on TiO2 was wellmodeled by the Langmuir adsorption isotherm. The adsorption of n-heneicosanoic acid (21A) followed Langmuir kinetics, whereas the net rates of adsorption of shorter n-alkanoic acids and Br6A were slower than predicted by simple Langmuir kinetics, suggesting that desorption was non-negligible. At high surface coverage, n-alkanoic acids with 14 or more methylene groups formed ordered, crystalline monolayers, as evidenced by shifts of asymmetric and symmetric CH2 stretching bands in IR spectra. The formation of ordered monolayers were well-modeled by an idealized mechanism, in which adsorption and desorption followed Langmuir kinetics and ordering was first-order with respect to the fractional surface coverage of adsorbates. Dispersion forces and ordering affected the compositions of mixed monolayers of 21A and Br6A on TiO2 films that remained in contact with mixed coadsorption solutions. When the fractional surface coverage of 21A was sufficiently high to induce ordering, it displaced Br6A from TiO2. We propose that these compositional changes were driven by the stabilization of 21A via cohesive lateral dispersion forces. CdSe QDs were attached to surfaces of

  17. Direct normal irradiance forecasting at dust sites based on aerosol data assimilation

    NASA Astrophysics Data System (ADS)

    Hoppe, Charlotte; Friese, Elmar; Berndt, Jonas; Elbern, Hendrik

    2016-04-01

    The optimal operation of concentrating solar thermal power plants (CSP) or concentrating photovoltaic plants (CPV) requires precise forecasts of direct normal irradiance (DNI). Aerosols have a strong impact on DNI. High aerosol loads may cause a reduction of DNI of up to 20-30% under clear-sky conditions. Thus, an accurate representation of the aerosol optical depth (AOD) is crucial for reliable DNI forecasts. Concentrating solar power plants are often located in desert/arid regions where dust events are likely to occur. For those locations with strong aerosol or especially dust sources in the vicinity, using only large scale, low resolution aerosol information from satellites might not be sufficient. Ground-based measurements of particulate matter (PM10 and PM2.5) provide additional, more precise, local information. On the other hand, sparsely populated desert areas are only poorly equipped with in-situ measurement devices. Thus, data assimilation seeks to make optimal use of all available observations. Within the EU FP7 project DNICast, assimilation based simulations are performed using the EURopean pollution Dispersion-Inverse Model (EURAD-IM) including a 3D/4D- Var data assimilation scheme and sophisticated aerosol dynamics and aerosol chemistry schemes. The setup includes all aerosol related observation streams along with routine data assimilation plus available on-site data and will provide assimilation based short term forecasts of AOD at selected test sites. The system is embedded in the European Earth observation system MACC (now: CAMS) and benefits from near-real time in situ and space borne measurements. The system is coupled to the WRF model to provide radiation forecasts based on aerosol information from the EURAD-IM data assimilation scheme. We will present simulation results for CSP sites on the Iberian Peninsula evaluating the gain of information obtained by data assimilation to capture small-scale dust events and large scale Saharan dust events

  18. KISMET tungsten dispersal experiment

    SciTech Connect

    Wohletz, K.; Kunkle, T.; Hawkins, W.

    1996-12-01

    Results of the KISMET tungsten dispersal experiment indicate a relatively small degree of wall-rock contamination caused by this underground explosive experiment. Designed as an add-on to the KISMET test, which was performed in the U-1a.02 drift of the LYNER facility at Nevada Test Site on 1 March 1995, this experiment involved recovery and analysis of wall-rock samples affected by the high- explosive test. The chemical, high-explosive blast drove tungsten powder, placed around the test package as a plutonium analog, into the surrounding wall- rock alluvium. Sample analyses by an analytical digital electron microscope (ADEM) show tungsten dispersed in the rock as tiny (<10 {mu}m) particles, agglomerates, and coatings on alluvial clasts. Tungsten concentrations, measured by energy dispersive spectral analysis on the ADEM, indicate penetration depths less than 0.1 m and maximum concentrations of 1.5 wt % in the alluvium.

  19. Analysis of the Performance Characteristics of the Five-Channel Microtops II Sun Photometer for Measuring Aerosol Optical Thickness and Precipitable Water Vapor

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Levy, Robert; Kaufman, Yoram; Remer, Lorraine A.; Li, Rong-Rong; Martins, Vanderlei J.; Holben, Brent N.; Abuhassan, Nader; Slutsker, Ilya; Eck, Thomas F.; Pietras, Christophe; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Five Microtops II sun photometers were studied in detail at the NASA Goddard Space Flight Center (GSFC) to determine their performance in measuring aerosol optical thickness (AOT or Tau(sub alphalambda) and precipitable column water vapor (W). Each derives Tau(sub alphalambda) from measured signals at four wavelengths lambda (340, 440, 675, and 870 nm), and W from the 936 nm signal measurements. Accuracy of Tau(sub alphalambda) and W determination depends on the reliability of the relevant channel calibration coefficient (V(sub 0)). Relative calibration by transfer of parameters from a more accurate sun photometer (such as the Mauna-Loa-calibrated AERONET master sun photometer at GSFC) is more reliable than Langley calibration performed at GSFC. It was found that the factory-determined value of the instrument constant for the 936 nm filter (k= 0.7847) used in the Microtops' internal algorithm is unrealistic, causing large errors in V(sub 0(936)), Tau(sub alpha936), and W. Thus, when applied for transfer calibration at GSFC, whereas the random variation of V(aub 0) at 340 to 870 nm is quite small, with coefficients of variation (CV) in the range of 0 to 2.4%, at 936 nm the CV goes up to 19%. Also, the systematic temporal variation of V(sub 0) at 340 to 870 nm is very slow, while at 936 nm it is large and exhibits a very high dependence on W. The algorithm also computes Tau(sub alpha936) as 0.91Tau(sub alpha870), which is highly simplistic. Therefore, it is recommended to determine Tau(sub alpha936) by logarithmic extrapolation from Tau(sub alpha675) and Tau(sub alpha 870. From the operational standpoint of the Microtops, apart from errors that may result from unperceived cloud contamination, the main sources of error include inaccurate pointing to the Sun, neglecting to clean the front quartz window, and neglecting to calibrate correctly. If these three issues are adequately taken care of, the Microtops can be quite accurate and stable, with root mean square (rms

  20. Aerosol mobility size spectrometer

    DOEpatents

    Wang, Jian; Kulkarni, Pramod

    2007-11-20

    A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housing includes an inlet for introducing a flow medium into the chamber in a flow direction, an aerosol injection port adjacent the inlet for introducing a charged aerosol sample into the chamber, a separation section for applying an electric field to the aerosol sample across the flow direction and an outlet opposite the inlet. In the separation section, the aerosol sample becomes entrained in the flow medium and the aerosol particles within the aerosol sample are separated by size into a plurality of aerosol flow streams under the influence of the electric field. The camera is disposed adjacent the housing outlet for optically detecting a relative position of at least one aerosol flow stream exiting the outlet and for optically detecting the number of aerosol particles within the at least one aerosol flow stream.

  1. Improving performance of HVAC systems to reduce exposure to aerosolized infectious agents in buildings; recommendations to reduce risks posed by biological attacks.

    PubMed

    Hitchcock, Penny J; Mair, Michael; Inglesby, Thomas V; Gross, Jonathan; Henderson, D A; O'Toole, Tara; Ahern-Seronde, Joa; Bahnfleth, William P; Brennan, Terry; Burroughs, H E Barney; Davidson, Cliff; Delp, William; Ensor, David S; Gomory, Ralph; Olsiewski, Paula; Samet, Jonathan M; Smith, William M; Streifel, Andrew J; White, Ronald H; Woods, James E

    2006-01-01

    The prospect of biological attacks is a growing strategic threat. Covert aerosol attacks inside a building are of particular concern. In the summer of 2005, the Center for Biosecurity of the University of Pittsburgh Medical Center convened a Working Group to determine what steps could be taken to reduce the risk of exposure of building occupants after an aerosol release of a biological weapon. The Working Group was composed of subject matter experts in air filtration, building ventilation and pressurization, air conditioning and air distribution, biosecurity, building design and operation, building decontamination and restoration, economics, medicine, public health, and public policy. The group focused on functions of the heating, ventilation, and air conditioning systems in commercial or public buildings that could reduce the risk of exposure to deleterious aerosols following biological attacks. The Working Group's recommendations for building owners are based on the use of currently available, off-the-shelf technologies. These recommendations are modest in expense and could be implemented immediately. It is also the Working Group's judgment that the commitment and stewardship of a lead government agency is essential to secure the necessary financial and human resources and to plan and build a comprehensive, effective program to reduce exposure to aerosolized infectious agents in buildings. PMID:16545023

  2. Turbulent Dispersion of Traffic Emissions

    NASA Astrophysics Data System (ADS)

    Staebler, R. M.; Gordon, M.; Liggio, J.; Makar, P.; Mihele, C.; Brook, J.; Wentzell, J. J.; Gong, S.; Lu, G.; Lee, P.

    2010-12-01

    Emissions from the transportation sector are a significant source of air pollution. Ongoing efforts to reduce the impacts require tools to provide guidance on policies regarding fuels, vehicle types and traffic control. The air quality models currently used to predict the effectiveness of policies typically treat traffic emissions as a source uniformly distributed across the surface of a model grid. In reality, emissions occur along lines above the surface, in an initially highly concentrated form, and are immediately mixed by traffic-enhanced turbulence. Differences between model and reality in terms of both chemistry and dispersion are to be expected. The ALMITEE (Advancing Local-scale Modeling through Inclusion of Transportation Emission Experiments) subproject FEVER (Fast Evolution of Vehicle Emissions from Roadways), conducted on multi-lane highways in the Toronto area in the summer of 2010, included measurements to quantify the evolution and dispersion of traffic emissions. Continuous micro-meteorological data (heat and momentum fluxes, temperature, humidity and incoming solar radiation) were collected 10m from the road, next to a traffic camera used to determine traffic density, composition and speed. Sonic anemometers and an aircraft turbulence probe mounted on a mobile lab provided measurements of turbulent dispersion both directly in traffic on the highway as well as on perpendicular side roads, as a function of distance from the highway. The mobile lab was equipped with instruments to characterize the aerosol size and mass distributions, aerosol composition including black carbon content, NO, NO2, CO2, CO, SO2 and VOCs at high time resolution. Preliminary results on the consequences of turbulent dispersion of traffic emissions levels under a variety of conditions will be disseminated.

  3. Results and code predictions for ABCOVE (aerosol behavior code validation and evaluation) aerosol code validation: Test AB6 with two aerosol species. [LMFBR

    SciTech Connect

    Hilliard, R K; McCormack, J C; Muhlestein, L D

    1984-12-01

    A program for aerosol behavior code validation and evaluation (ABCOVE) has been developed in accordance with the LMFBR Safety Program Plan. The ABCOVE program is a cooperative effort between the USDOE, the USNRC, and their contractor organizations currently involved in aerosol code development, testing or application. The second large-scale test in the ABCOVE program, AB6, was performed in the 850-m/sup 3/ CSTF vessel with a two-species test aerosol. The test conditions simulated the release of a fission product aerosol, NaI, in the presence of a sodium spray fire. Five organizations made pretest predictions of aerosol behavior using seven computer codes. Three of the codes (QUICKM, MAEROS and CONTAIN) were discrete, multiple species codes, while four (HAA-3, HAA-4, HAARM-3 and SOFIA) were log-normal codes which assume uniform coagglomeration of different aerosol species. Detailed test results are presented and compared with the code predictions for seven key aerosol behavior parameters.

  4. AEROSOL AND GAS MEASUREMENT

    EPA Science Inventory

    Measurements provide fundamental information for evaluating and managing the impact of aerosols on air quality. Specific measurements of aerosol concentration and their physical and chemical properties are required by different users to meet different user-community needs. Befo...

  5. Aerosols and environmental pollution

    NASA Astrophysics Data System (ADS)

    Colbeck, Ian; Lazaridis, Mihalis

    2010-02-01

    The number of publications on atmospheric aerosols has dramatically increased in recent years. This review, predominantly from a European perspective, summarizes the current state of knowledge of the role played by aerosols in environmental pollution and, in addition, highlights gaps in our current knowledge. Aerosol particles are ubiquitous in the Earth’s atmosphere and are central to many environmental issues; ranging from the Earth’s radiative budget to human health. Aerosol size distribution and chemical composition are crucial parameters that determine their dynamics in the atmosphere. Sources of aerosols are both anthropogenic and natural ranging from vehicular emissions to dust resuspension. Ambient concentrations of aerosols are elevated in urban areas with lower values at rural sites. A comprehensive understanding of aerosol ambient characteristics requires a combination of measurements and modeling tools. Legislation for ambient aerosols has been introduced at national and international levels aiming to protect human health and the environment.

  6. Aerosol/Cloud Measurements Using Coherent Wind Doppler Lidars

    NASA Astrophysics Data System (ADS)

    Royer, Philippe; Boquet, Matthieu; Cariou, Jean-Pierre; Sauvage, Laurent; Parmentier, Rémy

    2016-06-01

    The accurate localization and characterization of aerosol and cloud layers is crucial for climate studies (aerosol indirect effect), meteorology (Planetary Boundary Layer PBL height), site monitoring (industrial emissions, mining,…) and natural hazards (thunderstorms, volcanic eruptions). LEOSPHERE has recently developed aerosol/cloud detection and characterization on WINDCUBE long range Coherent Wind Doppler Lidars (CWDL). These new features combine wind and backscatter intensity informations (Carrier-to-Noise Ratio CNR) in order to detect (aerosol/cloud base and top, PBL height) and to characterize atmospheric structures (attenuated backscatter, depolarization ratio). For each aerosol/cloud functionality the method is described, limitations are discussed and examples are given to illustrate the performances.

  7. Stratospheric aerosol properties and their effects on infrared radiation.

    NASA Technical Reports Server (NTRS)

    Remsberg, E. E.

    1973-01-01

    This paper presents a stratospheric aerosol model and infers its effects on terrestrial radiation. Composition of the aerosol is assumed to be concentrated sulfuric acid. An appropriate size distribution has been determined from available size distribution measurements of other investigators. Aerosols composed of concentrated sulfuric acid emit energy in the atmospheric window region of the infrared spectrum, 8-13 microns. Laboratory measurements of optical constant data obtained at room temperature are presented for 75 and 90% aqueous sulfuric acid. Calculations of an aerosol extinction coefficient are then performed by using the above data. Effects of changes in aerosol phase and temperature are discussed but not resolved.

  8. Characterization of a Vortex Shaking Method for Aerosolizing Fibers

    PubMed Central

    Ku, Bon Ki; Deye, Gregory; Turkevich, Leonid A.

    2015-01-01

    Generation of well-dispersed, well-characterized fibers is important in toxicology studies. A vortex-tube shaking method is investigated using glass fibers to characterize the generated aerosol. Controlling parameters that were studied included initial batch amounts of glass fibers, preparation of the powder (e.g., preshaking), humidity, and airflow rate. Total fiber number concentrations and aerodynamic size distributions were typically measured. The aerosol concentration is only stable for short times (t < 10 min) and then falls precipitously, with concomitant changes in the aerosol aerodynamic size distribution; the plateau concentration and its duration both increase with batch size. Preshaking enhances the initial aerosol concentration and enables the aerosolization of longer fibers. Higher humidity strongly affects the particle size distribution and the number concentration, resulting in a smaller modal diameter and a higher number concentration. Running the vortex shaker at higher flow rates (Q > 0.3 lpm), yields an aerosol with a particle size distribution representative of the batch powder; running the vortex shaker at a lower aerosol flow rate (Q ~ 0.1 lpm) only aerosolizes the shorter fibers. These results have implications for the use of the vortex shaker as a standard aerosol generator. PMID:26635428

  9. Speciation of mercury in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Jia, Xiaoyu; Han, Yi; Liu, Xinli; Duan, Taicheng; Chen, Hangting

    2011-01-01

    The dispersive liquid-liquid microextraction (DLLME) combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry for the speciation of mercury in water samples was described. Firstly methylmercury (MeHg +) and mercury (Hg 2+) were complexed with sodium diethyldithiocarbamate, and then the complexes were extracted into carbon tetrachloride by using DLLME. Under the optimized conditions, the enrichment factors of 138 and 350 for MeHg + and Hg 2+ were obtained from only 5.00 mL sample solution. The detection limits of the analytes (as Hg) were 0.0076 ng mL -1 for MeHg + and 0.0014 ng mL -1 for Hg 2+, respectively. The relative standard deviations for ten replicate measurements of 0.5 ng mL -1 MeHg + and Hg 2+ were 6.9% and 4.4%, respectively. Standard reference material of seawater (GBW(E)080042) was analyzed to verify the accuracy of the method and the results were in good agreement with the certified values. Finally, the developed method was successfully applied for the speciation of mercury in three environmental water samples.

  10. Determination of aflatoxins in high-pigment content samples by matrix solid-phase dispersion and high-performance liquid chromatography.

    PubMed

    Hu, Yan-Yun; Zheng, Ping; Zhang, Zhao-Xiang; He, You-Zhao

    2006-06-14

    A fast, efficient, and cost-effective method was developed for the analysis of aflatoxins in farm commodities with high-pigment content, such as chili powder, green bean, and black sesame. The proposed method involved matrix solid-phase dispersion (MSPD) and high-performance liquid chromatography (HPLC)-fluorescence detection (FLD) with postcolumn electrochemical derivatization in a Kobra cell. The MSPD procedure combined the extraction with neutral alumina and pigment cleanup with graphitic carbon black (GCB) in a single step. The recoveries of aflatoxins ranged from 88% to 95% with the relative standard deviations (RSD) less than 6% (n = 6). The limits of detection (LODs) were 0.25 ng/g aflatoxin B1, G1, and 0.10 ng/g aflatoxin B2, G2, respectively. The analytical results obtained by MSPD were compared to those of the immunoaffinity column (IAC) cleanup method. No significant differences were found between the two methods by t-test at the 95% confidence level. PMID:16756336

  11. [Determination of nine estrogenic steroids in milk using matrix solid phase dispersion-ultra performance liquid chromatography with mass spectrometric detector].

    PubMed

    Liu, Hongcheng; Li, Ning; Lin, Tao; Shao, Jinliang; Li, Qiwan

    2015-11-01

    An analytical method for the multiresidue determination of nine estrogenic steroids in milk was developed by modified matrix solid phase dispersion (MSPD) purification and ultra performance liquid chromatography (UPLC) with mass spectrometric detector (MSD). The sensitivity and accuracy of MSD were better than that of ultraviolet detector. In comparison with traditional mass spectrometry, the merits of MSD were simpler in operation and shorter in starting time (5 min). The results showed that the limits of detection of the compounds with nucleophilic substitution were high in positive ion mode of MSD and were easily affected by environmental conditions. The matrix effects of milk samples reduced from 84%-160% to 80%-121% after MSPD purification. The intraday precision and interday precision of the nine estrogenic steroids were 0.87%-1.78% and 1.82%-3.79%, respectively. The average recoveries were 68.7%-94.7%, and the relative standard deviations (RSDs) were less than 10%. The limits of detection (LODs) were 0.5-10 μg/kg. The limits of quantification (LOQ) were 2-20 μg/kg. PMID:26939362

  12. Effects of Optical-density and Phase Dispersion of an Imperfect Band-limited Occulting Mask on the Broadband Performance of a TPF Coronagraph

    NASA Technical Reports Server (NTRS)

    Sidiek, Erkin; Balasubramanian, Kunjithapatham

    2007-01-01

    Practical image-plane occulting masks required by high-contrast imaging systems such as the TPF-Coronagraph introduce phase errors into the transmitting beam., or, equivalently, diffracts the residual starlight into the area of the final image plane used for detecting exo-planets. Our group at JPL has recently proposed spatially Profiled metal masks that can be designed to have zero parasitic phase at the center wavelength of the incoming broadband light with small amounts of' 00 and phase dispersions at other wavelengths. Work is currently underway to design. fabricate and characterize such image-plane masks. In order to gain some understanding on the behaviors of these new imperfect band-limited occulting masks and clarify how such masks utilizing different metals or alloys compare with each other, we carried out some modeling and simulations on the contrast performance of the high-contrast imaging testbed (HCIT) at .JPL. In this paper we describe the details of our simulations and present our results.

  13. Performance of a gaseous detector based energy dispersive X-ray fluorescence imaging system: Analysis of human teeth treated with dental amalgam

    NASA Astrophysics Data System (ADS)

    Silva, A. L. M.; Figueroa, R.; Jaramillo, A.; Carvalho, M. L.; Veloso, J. F. C. A.

    2013-08-01

    Energy dispersive X-ray fluorescence (EDXRF) imaging systems are of great interest in many applications of different areas, once they allow us to get images of the spatial elemental distribution in the samples. The detector system used in this study is based on a micro patterned gas detector, named Micro-Hole and Strip Plate. The full field of view system, with an active area of 28 × 28 mm2 presents some important features for EDXRF imaging applications, such as a position resolution below 125 μm, an intrinsic energy resolution of about 14% full width at half maximum for 5.9 keV X-rays, and a counting rate capability of 0.5 MHz. In this work, analysis of human teeth treated by dental amalgam was performed by using the EDXRF imaging system mentioned above. The goal of the analysis is to evaluate the system capabilities in the biomedical field by measuring the drift of the major constituents of a dental amalgam, Zn and Hg, throughout the tooth structures. The elemental distribution pattern of these elements obtained during the analysis suggests diffusion of these elements from the amalgam to teeth tissues.

  14. Simultaneous determination of six synthetic phenolic antioxidants in edible oils using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with diode array detection.

    PubMed

    Xu, Shuangjiao; Liu, Liangliang; Wang, Yanqin; Zhou, Dayun; Kuang, Meng; Fang, Dan; Yang, Weihua; Wei, Shoujun; Xiao, Aiping; Ma, Lei

    2016-08-01

    A simple, rapid, organic-solvent- and sample-saving pretreatment technique, called dispersive liquid-liquid microextraction, was developed for the determination of six synthetic phenolic antioxidants from edible oils before high-performance liquid chromatography with diode array detection. The entire procedure was composed of a two-step microextraction and a centrifugal process and could be finished in about 5 min, only consuming only 25 mg of sample and 1 mL of the organic solvent for each extraction. The influences of several important parameters on the microextraction efficiency were thoroughly investigated. Recovery assays for oil samples were spiked at three concentration levels, 50, 100 and 200 mg/kg, and provided recoveries in the 86.3-102.5% range with a relative standard deviation below 3.5%. The intra-day and inter-day precisions for the analysis were less than 3.8%. The proposed method was successfully applied for the determination of synthetic phenolic antioxidants in different oil samples, and satisfactory results were obtained. Thus, the developed method represents a viable alternative for the quality control of synthetic phenolic antioxidant concentrations in edible oils. PMID:27334034

  15. Characterization and stability study of polysorbate 20 in therapeutic monoclonal antibody formulation by multidimensional ultrahigh-performance liquid chromatography-charged aerosol detection-mass spectrometry.

    PubMed

    Li, Yi; Hewitt, Daniel; Lentz, Yvonne K; Ji, Junyan A; Zhang, Taylor Y; Zhang, Kelly

    2014-05-20

    Polysorbate 20 is a nonionic surfactant commonly used in the formulation of therapeutic monoclonal antibodies (mAb) to prevent protein denaturation and aggregation. It is critical to understand the molecular heterogeneity and stability of polysorbate 20 in mAb formulations as polysorbate can gradually degrade in aqueous solution over time by multiple pathways losing surfactant functions and leading to protein aggregation. The molecular heterogeneity of polysorbate and the interference from proteins and the excipient in the formulation matrix make it a challenge to study polysorbate in protein formulations. In this work, the characterization and stability study of polysorbate 20 in the presence of mAb formulation sample matrix is first reported using two-dimensional liquid chromatography (2DLC) coupled with charged aerosol detection (CAD) and mass spectrometry (MS) detection. A mixed-mode column that has both anion-exchange and reversed-phase properties was used in the first dimension to separate protein and polysorbate in the formulation sample, while polysorbate 20 esters were trapped online and then analyzed using an reversed-phase ultrahigh-performance liquid chromatography (RP-UHPLC) column in the second dimension to further separate the ester species. The MS served as the third dimension to further resolve as well as to identify the polysorbate ester subspecies. Another 2DLC method using a cation-exchange column in the first dimension and the same RP-UHPLC method in the second dimension was developed to analyze the degradation products of polysorbate 20. Stability samples of a protein drug product were studied using these two 2DLC-CAD-MS methods to separate, identify, and quantify the multiple ester species in polysorbate 20 and also to monitor the change of their corresponding degradants. We found different polysorbate esters degrade at different rates, and importantly, the degradation rates for some esters are different in the protein formulation compared to

  16. Aerosol distribution apparatus

    DOEpatents

    Hanson, W.D.

    An apparatus for uniformly distributing an aerosol to a plurality of filters mounted in a plenum, wherein the aerosol and air are forced through a manifold system by means of a jet pump and released into the plenum through orifices in the manifold. The apparatus allows for the simultaneous aerosol-testing of all the filters in the plenum.

  17. Solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1992-03-17

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration is disclosed. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  18. Improved solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1988-07-19

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  19. Solid aerosol generator

    DOEpatents

    Prescott, Donald S.; Schober, Robert K.; Beller, John

    1992-01-01

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates.

  20. Tropopsheric Aerosol Chemistry via Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Worsnop, Douglas

    2008-03-01

    A broad overview of size resolved aerosol chemistry in urban, rural and remote regions is evolving from deployment of aerosol mass spectrometers (AMS) throughout the northern hemisphere. Using thermal vaporization and electron impact ionization as universal detector of non-refractory inorganic and organic composition, the accumulation of AMS results represent a library of mass spectral signatures of aerosol chemistry. For organics in particular, mass spectral factor analysis provides a procedure for classifying (and simplifying) complex mixtures composed of the hundreds or thousands of individual compounds. Correlations with parallel gas and aerosol measurements (e.g. GC/MS, HNMR, FTIR) supply additional chemical information needed to interpret mass spectra. The challenge is to separate primary and secondary; anthropogenic, biogenic and biomass burning sources - and subsequent - transformations of aerosol chemistry and microphysics.

  1. Ensembles of satellite aerosol retrievals based on three AATSR algorithms within aerosol_cci

    NASA Astrophysics Data System (ADS)

    Kosmale, Miriam; Popp, Thomas

    2016-04-01

    Ensemble techniques are widely used in the modelling community, combining different modelling results in order to reduce uncertainties. This approach could be also adapted to satellite measurements. Aerosol_cci is an ESA funded project, where most of the European aerosol retrieval groups work together. The different algorithms are homogenized as far as it makes sense, but remain essentially different. Datasets are compared with ground based measurements and between each other. Three AATSR algorithms (Swansea university aerosol retrieval, ADV aerosol retrieval by FMI and Oxford aerosol retrieval ORAC) provide within this project 17 year global aerosol records. Each of these algorithms provides also uncertainty information on pixel level. Within the presented work, an ensembles of the three AATSR algorithms is performed. The advantage over each single algorithm is the higher spatial coverage due to more measurement pixels per gridbox. A validation to ground based AERONET measurements shows still a good correlation of the ensemble, compared to the single algorithms. Annual mean maps show the global aerosol distribution, based on a combination of the three aerosol algorithms. In addition, pixel level uncertainties of each algorithm are used for weighting the contributions, in order to reduce the uncertainty of the ensemble. Results of different versions of the ensembles for aerosol optical depth will be presented and discussed. The results are validated against ground based AERONET measurements. A higher spatial coverage on daily basis allows better results in annual mean maps. The benefit of using pixel level uncertainties is analysed.

  2. Auditory attention and multiattribute decision-making during a 33 h sleep-deprivation period: mean performance and between-subject dispersions.

    PubMed

    Linde, L; Edland, A; Bergström, M

    1999-05-01

    One purpose of this study was to compare attention in the evening (22:00 h), in the late night (04:00 h), in the morning (10:00 h) and in the afternoon (16:00 h) during a period of complete wakefulness beginning at 08:00 h with a mean daytime performance without sleep deprivation. Another purpose was to investigate sleep deprivation effects on a multi-attribute decision-making task with and without time pressure. Twelve sleep-deprived male students were compared with 12 male non-sleep-deprived students. Both groups were tested five times with an auditory attention and a symbol coding task. Significant declines (p < 0.05) in mean level of performance on the auditory attention task were found at 04:00, 10:00 and 16:00 h for subjects forced to the vigil. However, the effect of the sleep deprivation manifested itself even more in increased between-subject dispersions. There were no differences between time pressure and no time pressure on the decision-making task and no significant differences between sleep-deprived and non-sleep-deprived subjects in decision strategies. In fact, the pattern of decision strategies among the sleep-deprived subject was more similar to a pattern of decision strategies typical for non-stressful conditions than the pattern of decision strategies among the non-sleep-deprived subjects. This result may have been due to the fact that the sleep loss acted as a dearouser. Here too, however, the variances differed significantly among sleep-deprived and non-sleep-deprived subjects, indicating that the sleep-deprived subjects were more variable in their decision strategy pattern than the control group. PMID:10327892

  3. Simultaneous determination of seven phthalic acid esters in beverages using ultrasound and vortex-assisted dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

    PubMed

    Yılmaz, Pelin Köseoğlu; Ertaş, Abdulselam; Kolak, Ufuk

    2014-08-01

    A sensitive, rapid, and simple high-performance liquid chromatography with UV detection method was developed for the simultaneous determination of seven phthalic acid esters (dimethyl phthalate, dipropyl phthalate, di-n-butyl phthalate, benzyl butyl phthalate, dicyclohexyl phthalate, di-(2-ethylhexyl) phthalate, and di-n-octyl phthalate) in several kinds of beverage samples. Ultrasound and vortex-assisted dispersive liquid-liquid microextraction method was used. The separation was performed using an Intersil ODS-3 column (C18 , 250 × 4.6 mm, 5.0 μm) and a gradient elution with a mobile phase consisting of MeOH/ACN (50:50) and 0.2 M KH2 PO4 buffer. Analytes were detected by a UV detector at 230 nm. The developed method was validated in terms of linearity, limit of detection, limit of quantification, repeatability, accuracy, and recovery. Calibration equations and correlation coefficients (> 0.99) were calculated by least squares method with weighting factor. The limit of detection and quantification were in the range of 0.019-0.208 and 0.072-0.483 μg/L. The repeatability and intermediate precision were determined in terms of relative standard deviation to be within 0.03-3.93 and 0.02-4.74%, respectively. The accuracy was found to be in the range of -14.55 to 15.57% in terms of relative error. Seventeen different beverage samples in plastic bottles were successfully analyzed, and ten of them were found to be contaminated by different phthalic acid esters. PMID:24890649

  4. Aerosol backscatter studies supporting LAWS

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry

    1989-01-01

    Optimized Royal Signals and Radar Establishment (RSRE), Laser True Airspeed System (LATAS) algorithm for low backscatter conditions was developed. The algorithm converts backscatter intensity measurements from focused continuous-wave (CW) airborne Doppler lidar into backscatter coefficients. The performance of optimized algorithm under marginal backscatter signal conditions was evaluated. The 10.6 micron CO2 aerosol backscatter climatologies were statistically analyzed. Climatologies reveal clean background aerosol mode near 10(exp -10)/kg/sq m/sr (mixing ratio units) through middle and upper troposhere, convective mode associated with planetary boundary layer convective activity, and stratospheric mode associated with volcanically-generated aerosols. Properties of clean background mode are critical to design and simulation studies of Laser Atmospheric Wind Sounder (LAWS), a MSFC facility Instrument on the Earth Observing System (Eos). Previous intercomparisons suggested correlation between aerosol backscatter at CO2 wavelength and water vapor. Field measurements of backscatter profiles with MSFC ground-based Doppler lidar system (GBDLS) were initiated in late FY-88 to coincide with independent program of local rawinsonde releases and overflights by Multi-spectral Atmospheric Mapping Sensor (MAMS), a multi-channel infrared radiometer capable of measuring horizontal and vertical moisture distributions. Design and performance simulation studies for LAWS would benefit from the existence of a relationship between backscatter and water vapor.

  5. On measurements of aerosol-gas composition of the atmosphere during two expeditions in 2013 along the Northern Sea Route

    NASA Astrophysics Data System (ADS)

    Sakerin, S. M.; Bobrikov, A. A.; Bukin, O. A.; Golobokova, L. P.; Pol'kin, Vas. V.; Pol'kin, Vik. V.; Shmirko, K. A.; Kabanov, D. M.; Khodzher, T. V.; Onischuk, N. A.; Pavlov, A. N.; Potemkin, V. L.; Radionov, V. F.

    2015-11-01

    We presented the results of expedition measurements of the set of physical-chemical characteristics of atmospheric aerosol in areas of the Arctic and Far East seas, performed onboard RV Akademik Fedorov (17 August-22 September 2013) and RV Professor Khljustin (24 July-7 September 2013). The specific features of spatial distribution and time variations of aerosol optical depth (AOD) of the atmosphere in the wavelength range of 0.34-2.14 μm and boundary layer height, aerosol and black carbon mass concentrations, and disperse and chemical composition of aerosol are discussed. Over the Arctic Ocean (on the route of RV Akademik Fedorov) there is a decrease in aerosol and black carbon concentrations in a northeastern direction: higher values were observed in the region of Spitsbergen and near the Kola Peninsula; and minimum values were observed at northern margins of the Laptev Sea. Average AOD (0.5 μm) values in this remote region were 0.03; the aerosol and black carbon mass concentrations were 875 and 22 ng m-3, respectively. The spatial distributions of most aerosol characteristics over Far East seas show their latitudinal decrease in the northern direction. On transit of RV Professor Khljustin from the Japan Sea to the Chukchi Sea, the aerosol number concentration decreased on average from 23.7 to 2.5 cm-3, the black carbon mass concentration decreased from 150 to 50 ng m-3, and AOD decreased from 0.19 to 0.03. We analyzed the variations in the boundary layer height, measured by ship-based lidar: the average value was 520 m, and the maximal value was 1200 m. In latitudinal distribution of the boundary layer height, there is a characteristic minimum at a latitude of ~ 55° N. For water basins of eight seas, we present the chemical compositions of the water-soluble aerosol fraction (ions, elements) and small gas-phase species, as well as estimates of their vertical fluxes. It is shown that substances are mainly (75-89 %) supplied from the atmosphere to the sea

  6. On measurements of aerosol-gas composition of the atmosphere during two expeditions in 2013 along Northern Sea Route

    NASA Astrophysics Data System (ADS)

    Sakerin, S. M.; Bobrikov, A. A.; Bukin, O. A.; Golobokova, L. P.; Pol'kin, Vas. V.; Pol'kin, Vik. V.; Shmirko, K. A.; Kabanov, D. M.; Khodzher, T. V.; Pavlov, A. N.; Potemkin, V. L.; Radionov, V. F.

    2015-06-01

    We presented the results of expedition measurements of the set of physical-chemical characteristics of atmospheric aerosol in water basins of Arctic and Far East seas, performed onboard RV Akademik Fedorov (17 August-22 September 2013) and RV Professor Khljustin (24 July-7 September 2013). The specific features of spatial distribution and time variations of aerosol optical depth (AOD) of the atmosphere in the wavelength range of 0.34-2.14 μm and boundary layer height, aerosol and black carbon mass concentrations, and disperse and chemical composition of aerosol are discussed. Over the Arctic Ocean (on the route of RV Akademik Fedorov) there is a decrease in aerosol and black carbon concentrations in northeastern direction: higher values were observed in the region of Spitsbergen and near the Kola Peninsula; and minimum values were observed at northern margins of the Laptev Sea. Average AOD (0.5 μm) values in this remote region were 0.03; the aerosol and black carbon mass concentrations were 875 and 22 ng m-3, respectively. The spatial distributions of most aerosol characteristics over Far East seas show their latitudinal decrease in the northern direction. On transit of RV Professor Khljustin from Japan to Chukchi Sea, the aerosol number concentration decreased, on the average, from 23.7 to 2.5 cm-3, the black carbon mass concentration decreased from 150 to 50 ng m-3, and AOD decreased from 0.19 to 0.03. We analyzed the variations in the boundary layer height, measured by ship-based lidar: the average value was 520 m, and the maximal value was 1200 m. In latitudinal distribution of the boundary layer height, there is a characteristic minimum at latitude of ∼ 55° N. For water basins of eight seas, we present the chemical compositions of water-soluble aerosol fraction (ions, elements) and small gaseous impurities, as well as estimates of their vertical fluxes. It is shown that substances are mainly (75-89 %) supplied from the atmosphere to the sea surface

  7. Anthropogenic Aerosol Effects on Sea Surface Temperatures: Mixed-Layer Ocean Experiments with Explicit Aerosol Representation

    NASA Astrophysics Data System (ADS)

    Dallafior, Tanja; Folini, Doris; Wild, Martin; Knutti, Reto

    2014-05-01

    Anthropogenic aerosols affect the Earth's radiative balance both through direct and indirect effects. These effects can lead to a reduction of the incoming solar radiation at the surface, i.e. dimming, which may lead to a change in sea surface temperatures (SST) or SST pattern. This, in turn, may affect precipitation patterns. The goal of the present work is to achieve an estimate of the equilibrium SST changes under anthropogenic aerosol forcing since industrialisation. We show preliminary results from mixed-layer ocean (MLO) experiments with explicit aerosol representation performed with ECHAM6-HAM. The (fixed) MLO heat flux into the deep ocean was derived from atmosphere only runs with fixed climatological SSTs (1961-1990 average) and present day (year 2000) aerosols and GHG burdens. Some experiments we repeated with an alternative MLO deep ocean heat flux (based on pre-industrial conditions) to test the robustness of our results with regard to this boundary condition. The maximum surface temperature responses towards anthropogenic aerosol and GHG forcing (separately and combined) were derived on a global and regional scale. The same set of experiments was performed with aerosol and GHG forcings representative of different decades over the past one and a half centuries. This allows to assess how SST patterns at equilibrium changed with changing aerosol (and GHG) forcing. Correlating SST responses with the change in downward clear-sky and all-sky shortwave radiation provides a first estimate of the response to anthropogenic aerosols. Our results show a clear contrast in hemispheric surface temperature response, as expected from the inter-hemispheric asymmetry of aerosol forcing The presented work is part of a project aiming at quantifying the effect of anthropogenic aerosol forcing on SSTs and the consequences for global precipitation patterns. Results from this study will serve as a starting point for further experiments involving a dynamic ocean model, which

  8. A laboratory study of the performance of the handheld diffusion size classifier (DiSCmini) for various aerosols in the 15-400 nm range.

    PubMed

    Bau, S; Zimmermann, B; Payet, R; Witschger, O

    2015-02-01

    In addition to chemical composition, particle concentration and size are among the main parameters used to characterize exposure to airborne ultrafine or nanoparticles. To assess occupational inhalation exposure, real-time instruments are recommended in recent strategies published. Among portable devices for personal exposure assessment in the workplace, DiSCmini (Matter Aerosol AG, Switzerland) has been identified as a potential candidate with its capacity to measure the airborne nanoparticle concentration and average particle size with good time-resolution. Monodisperse and polydisperse test nanoaerosols of varying compositions and morphologies were produced in the laboratory using the CAIMAN facility. These aerosols covered a range of particle sizes between 15 and 400 nm and number concentrations from 700 to 840,000 cm(-3). The aerosols were used to investigate the behavior of DiSCmini, comparing experimental data to reference data. In spite of a slight tendency to underestimate particle size, all particle diameters, number concentrations and surface area concentrations measured were in the same order of magnitude as reference data. Furthermore, no significant effect due to particle composition or morphology was noted. PMID:25366997

  9. Implementation of the Missing Aerosol Physics into LLNL IMPACT

    SciTech Connect

    Chuang, C

    2005-02-09

    characteristics and composition of aerosols. These processes, together with other physical properties (i.e., size, density, and refractive index), determine the atmospheric lifetime of aerosols and their radiative forcing. To better represent physical properties of aerosols, we adapted an aerosol microphysics model that simulates aerosol size distribution. Work toward this goal was done in collaboration with Professor Anthony Wexler of University of California at Davis. Professor Wexler's group has developed sectional models of atmospheric aerosol dynamics that include an arbitrary number of size sections and chemical compounds or compound classes. The model, AIM (Aerosol Inorganic Model), is designed to predict the mass distribution and composition of urban and regional particulate matter (''Sun and Wexler'', 1998a, b). This model is currently incorporated into EPA's Models-3 air quality modeling platform/CMAQ (Community Multiscale Air Quality) to test its performance with previous simulations of CMAQ over the continental US.

  10. A Computationally Efficient Algorithm for Aerosol Phase Equilibrium

    SciTech Connect

    Zaveri, Rahul A.; Easter, Richard C.; Peters, Len K.; Wexler, Anthony S.

    2004-10-04

    Three-dimensional models of atmospheric inorganic aerosols need an accurate yet computationally efficient thermodynamic module that is repeatedly used to compute internal aerosol phase state equilibrium. In this paper, we describe the development and evaluation of a computationally efficient numerical solver called MESA (Multicomponent Equilibrium Solver for Aerosols). The unique formulation of MESA allows iteration of all the equilibrium equations simultaneously while maintaining overall mass conservation and electroneutrality in both the solid and liquid phases. MESA is unconditionally stable, shows robust convergence, and typically requires only 10 to 20 single-level iterations (where all activity coefficients and aerosol water content are updated) per internal aerosol phase equilibrium calculation. Accuracy of MESA is comparable to that of the highly accurate Aerosol Inorganics Model (AIM), which uses a rigorous Gibbs free energy minimization approach. Performance evaluation will be presented for a number of complex multicomponent mixtures commonly found in urban and marine tropospheric aerosols.

  11. Ensemble-Based Assimilation of Aerosol Observations in GEOS-5

    NASA Technical Reports Server (NTRS)

    Buchard, V.; Da Silva, A.

    2016-01-01

    MERRA-2 is the latest Aerosol Reanalysis produced at NASA's Global Modeling Assimilation Office (GMAO) from 1979 to present. This reanalysis is based on a version of the GEOS-5 model radiatively coupled to GOCART aerosols and includes assimilation of bias corrected Aerosol Optical Depth (AOD) from AVHRR over ocean, MODIS sensors on both Terra and Aqua satellites, MISR over bright surfaces and AERONET data. In order to assimilate lidar profiles of aerosols, we are updating the aerosol component of our assimilation system to an Ensemble Kalman Filter (EnKF) type of scheme using ensembles generated routinely by the meteorological assimilation. Following the work performed with the first NASA's aerosol reanalysis (MERRAero), we first validate the vertical structure of MERRA-2 aerosol assimilated fields using CALIOP data over regions of particular interest during 2008.

  12. Colloidal Dispersions

    NASA Astrophysics Data System (ADS)

    Russel, W. B.; Saville, D. A.; Schowalter, W. R.

    1992-03-01

    The book covers the physical side of colloid science from the individual forces acting between submicron particles suspended in a liquid through the resulting equilibrium and dynamic properties. The relevant forces include Brownian motion, electrostatic repulsion, dispersion attraction, both attraction and repulsion due to soluble polymer, and viscous forces due to relative motion between the particles and the liquid. The balance among Brownian motion and the interparticle forces decides the questions of stability and phase behavior. Imposition of external fields produces complex effects, i.e. electrokinetic phenomena (electric field), sedimentation (gravitational field), diffusion (concentration/chemical potential gradient), and non-Newtonian rheology (shear field). The treatment aims to impart a sound, quantitative understanding based on fundamental theory and experiments with well-characterized model systems. This broad grasp of the fundamentals lends insight and helps to develop the intuitive sense needed to isolate essential features of technological problems and design critical experiments. Some exposure to fluid mechanics, statistical mechanics, and electricity and magnetism is assumed, but each subject is reintroduced in a self-contained manner.

  13. The Influence of Free Tropospheric Aerosol on the Boundary Layer Aerosol Budget in the Arctic

    NASA Astrophysics Data System (ADS)

    Igel, A. L.; Ekman, A.; Leck, C.; Savre, J.; Tjernstrom, M. K. H.; Sedlar, J.

    2015-12-01

    Large-eddy simulations of the summertime high Arctic boundary layer with mixed-phase stratus clouds have been performed based on observations taken during the ASCOS[1] campaign. The model includes a prognostic aerosol scheme where accumulation mode aerosol particles can be activated into cloud droplets, impaction scavenged, and regenerated upon cloud droplet evaporation or ice crystal sublimation. Two sets of simulations were performed, one with a constant aerosol concentration in the boundary layer and free troposphere, and one with enhanced free tropospheric concentrations based on observed aerosol concentration profiles. We find that the rate of aerosol depletion in the boundary layer is an order of magnitude larger than the median surface emission rates measured over the open water, indicating that for the present case the surface emissions are unlikely to compensate for aerosol loss due to interactions with clouds. In this case study, when the enhanced free troposphere aerosol concentrations are included, the entrainment of these particles into the boundary layer is able to offset the loss of particles from aerosol-cloud interactions. These results suggest that enhanced levels of accumulation mode particles, if located at the cloud top, may be an important source of accumulation mode particles in the Arctic boundary layer. [1] The Arctic Summer Cloud Ocean Study (ASCOS) was conducted in 2008 with the overall aim to improve our understanding of stratus cloud formation and possible climate feedback processes over the central Arctic Ocean. Tjernström et al., 2014 give more details.

  14. Aerosols of Mongolian arid area

    NASA Astrophysics Data System (ADS)

    Golobokova, L.; Marinayte, I.; Zhamsueva, G.

    2012-04-01

    Sampling was performed in July-August 2005-2010 at Station Sain Shand (44°54'N, 110°07'E) in the Gobi desert (1000 m a.s.l.), West Mongolia. Aerosol samples were collected with a high volume sampler PM 10 (Andersen Instruments Inc., USA) onto Whatman-41 filters. The substance was extracted from the filters by de-ionized water. The solution was screened through an acetate-cellulose filter with 0.2 micron pore size. Ions of ammonium, sodium, potassium, magnesium, and calcium, as well as sulphate ions, nitrate ions, hydrocarbonate, chloride ions were determined in the filtrate by means of an atomic adsorption spectrometer Carl Zeiss Jena (Germany), a high performance liquid chromatographer «Milichrome A-02» (Russia), and an ionic chromatographer ICS-3000 (Dionex, USA). The PAH fraction was separated from aerosol samples using hexane extraction at room temperature under UV environment. The extract was concentrated to 0.1-0.2 ml and analysed by a mass-spectrometer "Agilent, GC 6890, MSD 5973 Network". Analysis of concentrations of aerosols components, their correlation ratios, and meteorological modeling show that the main factor affecting chemical composition of aerosols is a flow of contaminants transferred by air masses to the sampling area mainly from the south and south-east, as well as wind conditions of the area, dust storms in particular. Sulphate, nitrate, and ammonium are major ions in aerosol particles at Station Sain Shand. Dust-borne aerosol is known to be a sorbent for both mineral and organic admixtures. Polycyclic aromatic hydrocarbons (PAH) being among superecotoxicants play an important role among resistant organic substances. PAH concentrations were determined in the samples collected in 2010. All aerosol samples contained dominant PAHs with 5-6 benzene rings ( (benze(k)fluoranthen, benze(b)flouranthen, benze(a)pyren, benze(?)pyren, perylene, benze(g,h,i)perylene, and indene(1,2,3-c,d)pyrene). Their total quantity varied between 42 and 90

  15. Warm fog dispersal

    NASA Technical Reports Server (NTRS)

    Frost, W.

    1983-01-01

    The charged particle generator was further tested after some design modification. The generator performance was measured with additional instrumentation and found to confirm previous measurements. Plans for a field testing were than developed. The overall status of the program and the field test plans were presented to a group of atmospheric scientists and electrostatic experts at the NASA/MSFC sponsored USRA Workshop on Electrostatic Fog Dispersal at NCAR, Boulder, Colorado discussed in previous sections. The recommendations from this workshop are being evaluated as to whether NASA should proceed with the field test or whether further theoretical research on the phenomenon of electrostatic fog dispersal and additional development of the charged particle generator should be carried out. Information obtained from the USRA Workshop clearly identified three physical mechanisms that could possibly influence the fog dispersal process, which heretofore have not been considered, and which may provide additional insight to the direction of further fog dispersal work. These mechanisms are: the effect of corona discharge on the electric field strength at the surface, the influx of fog into the cleared volume by turbulent diffusion, and the increase in supersaturation as liquid water is removed, activating haze particles, and thus generating more fog. Plans are being formulated to investigate these mechanisms.

  16. Evaluating Aerosol Process Modules within the Framework of the Aerosol Modeling Testbed

    NASA Astrophysics Data System (ADS)

    Fast, J. D.; Velu, V.; Gustafson, W. I.; Chapman, E.; Easter, R. C.; Shrivastava, M.; Singh, B.

    2012-12-01

    Factors that influence predictions of aerosol direct and indirect forcing, such as aerosol mass, composition, size distribution, hygroscopicity, and optical properties, still contain large uncertainties in both regional and global models. New aerosol treatments are usually implemented into a 3-D atmospheric model and evaluated using a limited number of measurements from a specific case study. Under this modeling paradigm, the performance and computational efficiency of several treatments for a specific aerosol process cannot be adequately quantified because many other processes among various modeling studies (e.g. grid configuration, meteorology, emission rates) are different as well. The scientific community needs to know the advantages and disadvantages of specific aerosol treatments when the meteorology, chemistry, and other aerosol processes are identical in order to reduce the uncertainties associated with aerosols predictions. To address these issues, an Aerosol Modeling Testbed (AMT) has been developed that systematically and objectively evaluates new aerosol treatments for use in regional and global models. The AMT consists of the modular Weather Research and Forecasting (WRF) model, a series testbed cases for which extensive in situ and remote sensing measurements of meteorological, trace gas, and aerosol properties are available, and a suite of tools to evaluate the performance of meteorological, chemical, aerosol process modules. WRF contains various parameterizations of meteorological, chemical, and aerosol processes and includes interactive aerosol-cloud-radiation treatments similar to those employed by climate models. In addition, the physics suite from the Community Atmosphere Model version 5 (CAM5) have also been ported to WRF so that they can be tested at various spatial scales and compared directly with field campaign data and other parameterizations commonly used by the mesoscale modeling community. Data from several campaigns, including the 2006

  17. Infrared differential-absorption Mueller matrix spectroscopy and neural network-based data fusion for biological aerosol standoff detection.

    PubMed

    Carrieri, Arthur H; Copper, Jack; Owens, David J; Roese, Erik S; Bottiger, Jerold R; Everly, Robert D; Hung, Kevin C

    2010-01-20

    An active spectrophotopolarimeter sensor and support system were developed for a military/civilian defense feasibility study concerning the identification and standoff detection of biological aerosols. Plumes of warfare agent surrogates gamma-irradiated Bacillus subtilis and chicken egg white albumen (analytes), Arizona road dust (terrestrial interferent), water mist (atmospheric interferent), and talcum powders (experiment controls) were dispersed inside windowless chambers and interrogated by multiple CO(2) laser beams spanning 9.1-12.0 microm wavelengths (lambda). Molecular vibration and vibration-rotation activities by the subject analyte are fundamentally strong within this "fingerprint" middle infrared spectral region. Distinct polarization-modulations of incident irradiance and backscatter radiance of tuned beams generate the Mueller matrix (M) of subject aerosol. Strings of all 15 normalized elements {M(ij)(lambda)/M(11)(lambda)}, which completely describe physical and geometric attributes of the aerosol particles, are input fields for training hybrid Kohonen self-organizing map feed-forward artificial neural networks (ANNs). The properly trained and validated ANN model performs pattern recognition and type-classification tasks via internal mappings. A typical ANN that mathematically clusters analyte, interferent, and control aerosols with nil overlap of species is illustrated, including sensitivity analysis of performance. PMID:20090802

  18. Generating monodisperse pharmacological aerosols using the spinning-top aerosol generator.

    PubMed

    Biddiscombe, Martyn F; Barnes, Peter J; Usmani, Omar S

    2006-01-01

    Pharmacological aerosols of precisely controlled particle size and narrow dispersity can be generated using the spinning-top aerosol generator (STAG). The ability of the STAG to generate monodisperse aerosols from solutions of raw drug compounds makes it a valuable research instrument. In this paper, the versatility of this instrument has been further demonstrated by aerosolizing a range of commercially available nebulized pulmonary therapy preparations. Nebules of Flixotide (fluticasone propionate), Pulmicort (budesonide), Combivent (salbutamol sulphate and ipratropium bromide), Bricanyl (terbutaline sulphate), Atrovent(ipratropium bromide), and Salamol (salbutamol sulphate) were each mixed with ethanol and delivered to the STAG. Monodisperse drug aerosol distributions were generated with MMADs of 0.95-6.7 microm. To achieve larger particle sizes from the nebulizer drug suspensions, the STAG formed compound particle agglomerates derived from the smaller insoluble drug particles. These compound agglomerates behaved aerodynamically as a single particle, and this was verified using an aerodynamic particle sizer and an Andersen Cascade Impactor. Scanning electron microscope images demonstrated their physical structure. On the other hand using the nebulizer drug solutions, spherical particles proportional to the original droplet diameter were generated. The aerosols generated by the STAG can allow investigators to study the scientific principles of inhaled drug deposition and lung physiology for a range of therapeutic agents. PMID:17034300

  19. Rapid determination of phthalate esters in alcoholic beverages by conventional ionic liquid dispersive liquid-liquid microextraction coupled with high performance liquid chromatography.

    PubMed

    Fan, Yingying; Liu, Shuhui; Xie, Qilong

    2014-02-01

    A very simple, fast and environmentally friendly sample extraction method was proposed for the analysis of phthalate esters (PAEs, di-isobutyl phthalate (DIBP), dibutylphthalate (DBP), butylbenzylphthalate (BBP) and bis(2-ethylhexyl)phthalate (DEHP)) in alcoholic beverages by using conventional ionic liquid dispersive liquid-liquid microextraction. The samples were extracted by 160 μL 1-octyl-3-methylimidazolium hexafluorophosphate in the presence of appropriate amount of ethanol and 10% (w/v) sodium chloride solution; the enriched analytes in sedimented phases were analyzed by high performance liquid chromatography-diode array detector (HPLC-DAD). Under the optimum conditions, a satisfactory linearity (in the range of 0.02-1 μg mL(-1) for white spirits and 0.01-0.5 μg mL(-1) for red wines with the correlation coefficients (r) varying from 0.9983 to 1), acceptable recovery rates (88.5-103.5% for white spirits and 91.6-104.6% for red wines), good repeatability (RSD ≤ 8.0%) and low detection limits (3.1-4.2 ng mL(-1) for white spirits and 1.5-2.2 ng mL(-1) for red wines) were obtained. The developed method was successfully applied for the determination of the four PAEs in 30 white spirits and 11 red wines collected locally, and the DBP content in 63% (19:30) white spirits exceeded the specific migration limit of 0.3 mg kg(-1) established by international regulation. PMID:24401417

  20. Simultaneous determination of seven synthetic colorants in wine by dispersive micro-solid-phase extraction coupled with reversed-phase high-performance liquid chromatography.

    PubMed

    Zhang, Yun; Zhou, Hua; Wang, Yougang; Wu, Xianglun; Zhao, Yonggang

    2015-02-01

    A novel and effective dispersive micro-solid-phase extraction (d-µ-SPE) using ethanediamine-functionalized magnetic Fe3O4 polymer (EDA-MP) as an efficient adsorbent in wine sample was developed. Based on this, a simple and time-saving analytical method for the simultaneous determination of seven synthetic colorants (i.e., tartrazine, amaranth, carmine, sunset yellow, allura red, brilliant blue and erythrosine) in wine by reversed-phase high-performance liquid chromatography with an ultraviolet detector was established. The experimental parameters, including the chromatographic retention behavior of studied synthetic colorants, the effect of the usage amount of cross-linking monomer, the effect of the usage amount of EDA-MP on the recovery and the recyclability of the adsorbents, were studied in detail. The results showed that the EDA-MP could be reused efficiently at least six times. Under optimized conditions, the recoveries for all analytes were in the range of 88.6-105.2%, with the intraday relative standard deviations (RSDs) ranging from 2.1 to 8.2% and the interday RSDs ranging from 3.4 to 8.7%, and all the analytes had good linearities in the tested ranges with correlation coefficients (r(2)) >0.9995. The limits of quantification for seven synthetic colorants were between 0.12 and 0.45 mg L(-1). The developed method was successfully applied to wine samples, and it was confirmed that the EDA-MP particles were highly effective d-µ-SPE materials. PMID:24850700

  1. X-RAY FLUORESCENCE ANALYSIS OF FILTER-COLLECTED AEROSOL PARTICLES

    EPA Science Inventory

    X-ray fluorescence (XRF) has become an effective technique for determining the elemental content of aerosol samples. For quantitative analysis, the aerosol particles must be collected as uniform deposits on the surface of Teflon membrane filters. An energy dispersive XRF spectrom...

  2. APPLICATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE INDOOR AIR EMISSIONS FROM AEROSOL CONSUMER PRODUCTS (PROJECT SUMMARY)

    EPA Science Inventory

    report gives results of research, undertaken to develop tools and meth-odologies to measure aerosol chemical and particle dispersion through space. Georgia Tech Research Institute re-searchers built an Aerosol Mass Spec-tral Interface (AMSI), which is interfaced with a mass spect...

  3. QT dispersion in adult hypertensives.

    PubMed Central

    Sani, Isa Muhammad; Solomon, Danbauchi Sulei; Imhogene, Oyati Albert; Ahmad, Alhassan Muhammad; Bala, Garko Sani

    2006-01-01

    Increased QT dispersion is associated with sudden cardiac death in congestive cardiac failure, hypertrophic cardiomyopathy and following myocardial infarction. Patients with hypertension--in particular, those with left ventricular hypertrophy (LVH)--are also at greater risk of sudden cardiac death. We examined whether QT dispersion, which is easily obtained from a routine ECG, correlates with LVH. One-hundred untreated patients with systemic hypertension and 78 normotensives had QT dispersion measured manually from a surface 12-lead electrocardiogram and two-dimensional echocardiography performed to measure interventricular septal thickness, posterior wall thickness and left ventricular internal diameter. Office blood pressure was also recorded. Multivariate analysis demonstrated significant relationships between QT dispersion and office systolic blood pressure, and left ventricular mass index. Manual measurement of QT dispersion might be a simple, noninvasive screening procedure to identify those hypertensives at greatest risk of sudden cardiac death in a third-world country. PMID:16623077

  4. PIXE Analysis of Indoor Aerosols

    NASA Astrophysics Data System (ADS)

    Johnson, Christopher; Turley, Colin; Moore, Robert; Battaglia, Maria; Labrake, Scott; Vineyard, Michael

    2011-10-01

    We have performed a proton-induced X-ray emission (PIXE) analysis of aerosol samples collected in academic buildings at Union College to investigate the air quality in these buildings and the effectiveness of their air filtration systems. This is also the commissioning experiment for a new scattering chamber in the Union College Ion-Beam Analysis Laboratory. The aerosol samples were collected on Kapton foils using a nine-stage cascade impactor that separates particles according to their aerodynamic size. The foils were bombarded with beams of 2.2-MeV protons from the Union College 1.1-MV Pelletron Accelerator and the X-ray products were detected with an Amptek silicon drift detector. After subtracting the contribution from the Kapton foils, the X-ray energy spectra of the aerosol samples were analyzed using GUPIX software to determine the elemental concentrations of the samples. We will describe the collection of the aerosol samples, discuss the PIXE analysis, and present the results.

  5. Airborne Atmospheric Aerosol Measurement System

    NASA Astrophysics Data System (ADS)

    Ahn, K.; Park, Y.; Eun, H.; Lee, H.

    2015-12-01

    It is important to understand the atmospheric aerosols compositions and size distributions since they greatly affect the environment and human health. Particles in the convection layer have been a great concern in global climate changes. To understand these characteristics satellite, aircraft, and radio sonde measurement methods have usually been used. An aircraft aerosol sampling using a filter and/or impactor was the method commonly used (Jay, 2003). However, the flight speed particle sampling had some technical limitations (Hermann, 2001). Moreover, the flight legal limit, altitude, prohibited airspace, flight time, and cost was another demerit. To overcome some of these restrictions, Tethered Balloon Package System (T.B.P.S.) and Recoverable Sonde System(R.S.S.) were developed with a very light optical particle counter (OPC), impactor, and condensation particle counter (CPC). Not only does it collect and measure atmospheric aerosols depending on altitudes, but it also monitors the atmospheric conditions, temperature, humidity, wind velocity, pressure, GPS data, during the measurement (Eun, 2013). In this research, atmospheric aerosol measurement using T.B.P.S. in Ansan area is performed and the measurement results will be presented. The system can also be mounted to an unmanned aerial vehicle (UAV) and create an aerial particle concentration map. Finally, we will present measurement data using Tethered Balloon Package System (T.B.P.S.) and R.S.S (Recoverable Sonde System).

  6. Optimal Aerosol Parameterization for Remote Sensing Retrievals

    NASA Technical Reports Server (NTRS)

    Newchurch, Michael J.

    2004-01-01

    discrepancy in the lower stratosphere is attributable to natural variation, and is also seen in comparisons between lidar and ozonesonde measurements. NO2 profiles obtained with our algorithm were compared to those obtained through the SAGE III operational algorithm and exhibited differences of 20 - 40%. Our retrieved profiles agree with the HALOE NO2 measurements significantly better than those of the operational retrieval. In other work (described below), we are extending our aerosol retrievals into the infrared regime and plan to perform retrievals from combined uv-visible-infrared spectra. This work will allow us to use the spectra to derive the size and composition of aerosols, and we plan to employ our algorithms in the analysis of PSC spectra. We are presently also developing a limb-scattering algorithm to retrieve aerosol data from limb measurements of solar scattered radiation.

  7. Characterization of Speciated Aerosol Direct Radiative Forcing Over California

    SciTech Connect

    Zhao, Chun; Leung, Lai-Yung R.; Easter, Richard C.; Hand, Jenny; Avise, J.

    2013-03-16

    . Aerosol radiative forcing is presented along with the contribution from individual aerosol species from the simulation with anthropogenic EC emission doubled. On statewide average over California, aerosol reduces the seasonal-average surface radiation fluxes by about 3 W m-2 with a maximum of 10 W m-2 in summer. In the atmosphere, aerosol introduces a warming effect of about 2 W m-2 with a maximum of 10 W m-2 also in summer. EC and dust contribute about 75-95% and 1-10% of the total warming through the seasons, respectively. At the top of atmosphere (TOA), the overall aerosol radiative effect is cooling with a maximum of -3.5 W m-2. EC contributes exclusively to the TOA warming of up to about 0.7 W m-2. The encouraging performance of WRF-Chem in simulating aerosols and their radiative forcing suggests that the model is suitable for further investigation of the impact of emission control on radiative forcing and regional climate over California.

  8. Application of a coupled aerosol formation: Radiative transfer model to climatic studies of aerosols

    NASA Technical Reports Server (NTRS)

    Toon, O. B.; Pollack, J. B.

    1979-01-01

    A sophisticated one dimensional physical-chemical model of the formation and evolution of stratospheric aerosols was used to predict the size and number concentration of the stratospheric aerosols as functions of time and altitude following: a large volcanic eruption; increased addition of carbonyl sulfide (OCS) or sulfur dioxide (SO2) to the troposphere; increased supersonic aircraft (SST) flights in the stratosphere; and, large numbers of space shuttle (SS) flights through the stratosphere. A radiative-convective one dimensional climate sensitivity study, using the results of the aerosol formation model, was performed to assess the ground level climatic significance of these perturbations to the stratospheric aerosol layer. Volcanic eruptions and large OCS or SO2 increases could cause significant climatic changes. Currently projected SS launches and moderate fleets of SST's are unlikely to upset the stratospheric aerosol layer enough to significantly impact climate.

  9. Rifapentine-loaded PLGA microparticles for tuberculosis inhaled therapy: Preparation and in vitro aerosol characterization.

    PubMed

    Parumasivam, Thaigarajan; Leung, Sharon S Y; Quan, Diana Huynh; Triccas, Jamie A; Britton, Warwick J; Chan, Hak-Kim

    2016-06-10

    Inhaled delivery of drugs incorporated into poly (lactic-co-glycolic acid) (PLGA) microparticles allows a sustained lung concentration and encourages phagocytosis by alveolar macrophages that harboring Mycobacterium tuberculosis. However, limited data are available on the effects of physicochemical properties of PLGA, including the monomer ratio (lactide:glycide) and molecular weight (MW) on the aerosol performance, macrophage uptake, and toxicity profile. The present study aims to address this knowledge gap, using PLGAs with monomer ratios of 50:50, 75:25 and 85:15, MW ranged 24 - 240kDa and an anti-tuberculosis (TB) drug, rifapentine. The PLGA-rifapentine powders were produced through a solution spray drying technique. The particles were spherical with a smooth surface and a volume median diameter around 2μm (span ~2). When the powders were dispersed using an Osmohaler(®) at 100L/min for 2.4s, the fine particle fraction (FPFtotal, wt.% particles in aerosol <5μm relative to the total recovered drug mass) was ranged between 52 and 57%, with no significant difference between the formulations. This result suggests that the monomer ratio and MW are not crucial parameters for the aerosol performance of PLGA. The phagocytosis analysis was performed using Thp-1 monocyte-derived macrophages. The highest rate of uptake was observed in PLGA 85:15 followed by 75:25 and 50:50 with about 90%, 80% and 70%, respectively phagocytosis over 4h of exposure. Furthermore, the cytotoxicity analysis on Thp-1 and human lung adenocarcinoma epithelial cells demonstrated that PLGA concentration up to 1.5mg/mL, regardless of the monomer composition and MW, were non-toxic. In conclusion, the monomer ratio and MW are not crucial in determining the aerosol performance and cytotoxicity profile of PLGA however, the particles with high lactide composition have a superior tendency for macrophage uptake. PMID:27049049

  10. Transmission electron microscopy study of aerosol particles from the brown hazes in northern China

    NASA Astrophysics Data System (ADS)

    Li, Weijun; Shao, Longyi

    2009-05-01

    Airborne aerosol collections were performed in urban areas of Beijing that were affected by regional brown haze episodes over northern China from 31 May to 12 June 2007. Morphologies, elemental compositions, and mixing states of 810 individual aerosol particles of different sizes were obtained by transmission electron microscopy coupled with energy-dispersive X-ray spectrometry. The phases of some particles were verified using selected-area electron diffraction. Aerosol particle types less than 10 μm in diameter include mineral, complex secondary (Ca-S, K-, and S-rich), organic, soot, fly ash, and metal (Fe-rich and Zn-bearing). Most soot, fly ash, and organic particles are less than 2 μm in diameter. Approximately 84% of the analyzed mineral particles have diameters between 2 and 10 μm, while 81% of the analyzed complex secondary and metal particles are much smaller, from 0.1 to 2 μm. Trajectory analysis with fire maps show that southerly air masses arriving at Beijing have been transported through many agricultural biomass burning sites and heavy industrial areas. Spherical fly ash and Fe-rich particles were from industrial emissions, and abundant K-rich and organic particles likely originated from field burning of crop residues. Abundant Zn-bearing particles are associated with industrial activities and local waste incinerators. On the basis of the detailed analysis of 443 analyzed aerosol particles, about 70% of these particles are internally mixed with two or more aerosol components from different sources. Most mineral particles are covered with visible coatings that contain N, O, Ca (or Mg), minor S, and Cl. K- and S-rich particles tend to be coagulated with fly ash, soot, metal, and fine-grained mineral particles. Organic materials internally mixed with K- and S-rich particles can be their inclusions and coatings.

  11. Measurements of Atmospheric Aerosol Vertical Distributions above Svalbard, Norway using Unmanned Aerial Systems (UAS)

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Johnson, J. E.; Stalin, S.; Telg, H.; Murphy, D. M.; Burkhart, J. F.; Quinn, P.; Storvold, R.

    2015-12-01

    Atmospheric aerosol vertical distributions were measured above Svalbard, Norway in April 2015 to investigate the processes controlling aerosol concentrations and radiative effects. The aerosol payload was flown in a NOAA/PMEL MANTA Unmanned Aerial System (UAS) on 9 flights totaling 19 flight hours. Measurements were made of particle number concentration and aerosol light absorption at three wavelengths, similar to those conducted in April 2011 (Bates et al., Atmos. Meas. Tech., 6, 2115-2120, 2013). A filter sample was collected on each flight for analyses of trace elements. Additional measurements in the aerosol payload in 2015 included aerosol size distributions obtained using a Printed Optical Particle Spectrometer (POPS) and aerosol optical depth obtained using a four wavelength miniature Scanning Aerosol Sun Photometer (miniSASP). The data show most of the column aerosol mass and resulting optical depth in the boundary layer but frequent aerosol layers aloft with high particle number concentration (2000 cm-3) and enhanced aerosol light absorption (1 Mm-1). Transport of these aerosol layers was assessed using FLEXPART particle dispersion models. The data contribute to an assessment of sources of BC to the Arctic and potential climate impacts.

  12. Chemical characterization of secondary organic aerosol constituents from isoprene ozonolysis in the presence of acidic aerosol

    NASA Astrophysics Data System (ADS)

    Riva, Matthieu; Budisulistiorini, Sri Hapsari; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.

    2016-04-01

    Isoprene is the most abundant non-methane hydrocarbon emitted into Earth's atmosphere and is predominantly derived from terrestrial vegetation. Prior studies have focused largely on the hydroxyl (OH) radical-initiated oxidation of isoprene and have demonstrated that highly oxidized compounds, such as isoprene-derived epoxides, enhance the formation of secondary organic aerosol (SOA) through heterogeneous (multiphase) reactions on acidified sulfate aerosol. However, studies on the impact of acidified sulfate aerosol on SOA formation from isoprene ozonolysis are lacking and the current work systematically examines this reaction. SOA was generated in an indoor smog chamber from isoprene ozonolysis under dark conditions in the presence of non-acidified or acidified sulfate seed aerosol. The effect of OH radicals on SOA chemical composition was investigated using diethyl ether as an OH radical scavenger. Aerosols were collected and chemically characterized by ultra performance liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) and gas chromatography/electron impact ionization-mass spectrometry (GC/EI-MS). Analysis revealed the formation of highly oxidized compounds, including organosulfates (OSs) and 2-methylterols, which were significantly enhanced in the presence of acidified sulfate seed aerosol. OSs identified in the chamber experiments were also observed and quantified in summertime fine aerosol collected from two rural locations in the southeastern United States during the 2013 Southern Oxidant and Aerosol Study (SOAS).

  13. Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds

    SciTech Connect

    Turner, David, D.; Ferrare, Richard, A.

    2011-07-06

    The 'Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds' project focused extensively on the analysis and utilization of water vapor and aerosol profiles derived from the ARM Raman lidar at the Southern Great Plains ARM site. A wide range of different tasks were performed during this project, all of which improved quality of the data products derived from the lidar or advanced the understanding of atmospheric processes over the site. These activities included: upgrading the Raman lidar to improve its sensitivity; participating in field experiments to validate the lidar aerosol and water vapor retrievals; using the lidar aerosol profiles to evaluate the accuracy of the vertical distribution of aerosols in global aerosol model simulations; examining the correlation between relative humidity and aerosol extinction, and how these change, due to horizontal distance away from cumulus clouds; inferring boundary layer turbulence structure in convective boundary layers from the high-time-resolution lidar water vapor measurements; retrieving cumulus entrainment rates in boundary layer cumulus clouds; and participating in a field experiment that provided data to help validate both the entrainment rate retrievals and the turbulent profiles derived from lidar observations.

  14. Stratospheric Aerosol Injection for Geoengineering Purposes

    NASA Astrophysics Data System (ADS)

    Turco, R. P.; Yu, F.

    2008-12-01

    A number of studies have focused on the large-scale aspects of massive stratospheric aerosol injections for the purpose of modifying global climate to counterbalance current and future greenhouse warming effects. However, no descriptions of actual injection schemes have been presented at any level of detail; it is generally assumed that the procedure would be straightforward. Approaches mentioned include direct injection of dispersed microparticles of sulfates or other mineral particles, or the emission of precursor vapors, such as sulfur dioxide or hydrogen sulfide, that lead to particle formation. Using earlier aircraft plume research as a guide, we investigate the fate of injected aerosols/precursors from a stratospheric platform in terms of the chemical and microphysical evolution occurring in a mixing plume. We utilize an advanced microphysics model that treats nucleation, coagulation, condensation and other processes relevant to the injection of particulates at high altitudes, as well as the influence of plume dilution. The requirements of particle size and concentration for producing the desired engineered radiative forcing place significant constraints on the injection system. Here, we focus on the effects of early microphysical processing on the formation of a suitable aerosol layer, and consider strategies to overcome potential hurdles. Among the problems explicitly addressed are: the propensity for emitted particles to coagulate to sizes that are optically inefficient at solar wavelengths, accelerated scavenging by an enhanced background aerosol layer, the evolution of size dispersion leading to significant infrared effects, and total mass injection rates implied by stratospheric residence times. We also investigate variability in aerosol properties owing to uncertain nucleation rates in evolving plumes. In the context of the microphysical simulations, we discuss infrastructure requirements in terms of the scale of the intervention and, hence, the

  15. Evaluation of Enviro-HIRLAM model and aerosols effect during wildfires episodes in Europe and Central Russia in summer 2010

    NASA Astrophysics Data System (ADS)

    Nuterman, Roman; Pagh Nielsen, Kristian; Baklanov, Alexander; Kaas, Eigil

    2014-05-01

    The summer of 2010 was characterized by severe weather events such as floods, heat waves and droughts across Middle East, most of Europe and European Russia. Among them the wildfires in Portugal and European Russia were some of the most prominent and led to substantial increase of atmospheric aerosols concentration. For instance, pollution from Russian wildfires, which were the most noticeable, spread around the entire central part of the country and also dispersed towards the Northern Europe. This study is devoted to Enviro-HIRLAM (Environment - HIgh Resolution Limited Area Model) model evaluation and analysis of radiation balance change due to increased aerosol burden caused by wildfires in Russia. For this purpose the model was forced by boundary and initial conditions produced by ECMWF (European Center for Medium-Range Weather Forecast) IFS and MOZART models for meteorology and atmospheric composition, respectively. The model setup included aerosol microphysics module M7 with simple tropospheric sulfur chemistry, anthropogenic emissions by TNO, wildfires emissions by FMI and interactive sea-salt and dust emissions. During the model run surface data assimilation of meteorological parameters was applied. The HIRLAM Savijarvi radiation scheme has been improved to account explicitly for aerosol radiation interactions. So that the short-wave radiative transfer calculations are performed as standard 2-stream calculations for averages of aerosol optical properties weighted over the entire spectrum. The model shows good correlation of particulate matter (PM) concentrations on diurnal cycle as well as day-to-day variability, but one always has negative bias of PM. The Enviro-HIRLAM is able to capture concentration peaks both from short-term and long-term trans boundary transport of PM and predicted the Aerosol Optical Thickness (at 550 nm) up to 2 over wildfire-polluted regions. And the direct radiative forcing is less than -100 W/m2.

  16. Temperature-assisted On-column Solute Focusing: A General Method to Reduce Pre-column Dispersion in Capillary High Performance Liquid Chromatography

    PubMed Central

    Groskreutz, Stephen R.; Weber, Stephen G.

    2014-01-01

    Solvent-based on-column focusing is a powerful and well known approach for reducingthe impact of pre-column dispersion in liquid chromatography. Here we describe an orthogonal temperature-based approach to focusing called temperature-assisted on-column solute focusing (TASF). TASF is founded on the same principles as the more commonly used solvent-based method wherein transient conditions are created thatlead to high solute retention at the column inlet. Combining the low thermal mass of capillary columns and the temperature dependence of solute retentionTASF is used effectivelyto compress injection bands at the head of the column through the transient reduction in column temperature to 5 °C for a defined 7 mm segment of a 6 cm long 150 μm I.D. column. Following the 30 second focusing time, the column temperature is increased rapidly to the separation temperature of 60 °C releasing the focused band of analytes. We developed a model tosimulate TASF separations based on solute retention enthalpies, focusing temperature, focusing time, and column parameters. This model guides the systematic study of the influence of sample injection volume on column performance.All samples have solvent compositions matching the mobile phase. Over the 45 to 1050 nL injection volume range evaluated, TASF reducesthe peak width for all soluteswith k’ greater than or equal to 2.5, relative to controls. Peak widths resulting from injection volumes up to 1.3 times the column fluid volume with TASF are less than 5% larger than peak widths from a 45 nL injection without TASF (0.07 times the column liquid volume). The TASF approach reduced concentration detection limits by a factor of 12.5 relative to a small volume injection for low concentration samples. TASF is orthogonal to the solvent focusing method. Thus, it canbe used where on-column focusing is required, but where implementation of solvent-based focusing is difficult. PMID:24973805

  17. Thermoluminescent aerosol analysis

    NASA Technical Reports Server (NTRS)

    Rogowski, R. S.; Long, E. R., Jr. (Inventor)

    1977-01-01

    A method for detecting and measuring trace amounts of aerosols when reacted with ozone in a gaseous environment was examined. A sample aerosol was exposed to a fixed ozone concentration for a fixed period of time, and a fluorescer was added to the exposed sample. The sample was heated in a 30 C/minute linear temperature profile to 200 C. The trace peak was measured and recorded as a function of the test aerosol and the recorded thermoluminescence trace peak of the fluorescer is specific to the aerosol being tested.

  18. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1997-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size resolved aerosol microphysics and chemistry. Both profiles included pollution haze layer from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core.

  19. Remote sensing of aerosol properties during CARES

    NASA Astrophysics Data System (ADS)

    Kassianov, Evgueni; Barnard, James; Pekour, Mikhail; Flynn, Connor; Ferrare, Richard; Hostetler, Chris; Hair, John; Jobson, Bertram T.

    2011-11-01

    One month of MFRSR data collected at two sites in the central California (USA) region during the CARES campaign are processed and the MFRSR-derived AODs at 500 nm wavelength are compared with available AODs provided by AERONET measurements. We find that the MFRSR and AERONET AODs are small (~0.05) and comparable. A reasonable quantitative agreement between column aerosol size distributions (up to 2 μm) from the MFRSR and AERONET retrievals is illustrated as well. Analysis of the retrieved (MFRSR and AERONET) and in situ measured aerosol size distributions suggests that the contribution of the coarse mode to aerosol optical properties is substantial for several days. The results of a radiative closure experiment performed for the two sites and one-month period show a favorable agreement between the calculated and measured broadband downwelling irradiances (bias does not exceed about 3 Wm-2), and thus imply that the MFRSR-derived aerosol optical properties are reasonable.

  20. Remote Sensing of Aerosol Properties during CARES

    SciTech Connect

    Kassianov, Evgueni I.; Barnard, James C.; Pekour, Mikhail S.; Flynn, Connor J.; Ferrare, R.; Hostetler, Chris A.; Hair, John; Jobson, Bertram Thomas

    2011-10-01

    One month of MFRSR data collected at two sites in the central California (USA) region during the CARES campaign are processed and the MFRSR-derived AODs at 500 nm wavelength are compared with available AODs provided by AERONET measurements. We find that the MFRSR and AERONET AODs are small ({approx}0.05) and comparable. A reasonable quantitative agreement between column aerosol size distributions (up to 2 um) from the MFRSR and AERONET retrievals is illustrated as well. Analysis of the retrieved (MFRSR and AERONET) and in situ measured aerosol size distributions suggests that the contribution of the coarse mode to aerosol optical properties is substantial for several days. The results of a radiative closure experiment performed for the two sites and one-month period show a favorable agreement between the calculated and measured broadband downwelling irradiances (bias does not exceed about 3 Wm-2), and thus imply that the MFRSR-derived aerosol optical properties are reasonable.

  1. Pyrene-end-functionalized poly(L-lactide) as an efficient carbon nanotube dispersing agent in poly(L-lactide): mechanical performance and biocompatibility study.

    PubMed

    Martínez de Arenaza, I; Obarzanek-Fojt, M; Sarasua, J R; Meaurio, E; Meyer, F; Raquez, J M; Dubois, P; Bruinink, A

    2015-08-01

    In order to improve the mechanical properties of poly(L-lactide) (PLLA) based implants, a study was made of how far well dispersed multi-walled carbon nanotubes (MWCNTs) within a PLLA matrix were able to positively affect these properties. To this end, pyrene-end-functionalized poly(L-lactide) (py-end-PLLA) was evaluated as a dispersing agent. Transmission electron microscopy (TEM) analyses and mechanical tests of MWCNTs-based materials demonstrated an enhancement of MWCNT dispersion in the PLLA matrix and improved Young's modulus (E) when 4 wt% of py-end-PLLA was used as the dispersing agent. Subsequently, the bioacceptance of PLLA/py-end-PLLA/MWCNTs nanocomposites was evaluated using human bone marrow stromal cells (HBMC) in vitro. The inclusion of py-end-PLLA and MWCNTs supported HBMC adhesion and proliferation. The expression levels of the bone-specific markers indicated that the cells kept their potential to undergo osteogenic differentiation. The results of this study indicate that the addition of MWCNT combined with py-end-PLLA in PLLA/py-end-PLLA/MWCNTs nanocomposites may widen the range of applications of PLLA within the field of bone tissue engineering thanks to their mechanical strength and cytocompatibility. PMID:26154591

  2. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    to carbonyl- and nitro- functional groups on conjugated and aromatic organic structures (e.g. PAH, and terpene derived products). Using 12-hour fine (0.1-1.0 micron) aerosol samples collected in the field on quartz filters, uv/vis and infrared spectra were obtained in the laboratory using integrating spheres and diffuse reflectance spectroscopy, respectively. An inter-comparison of the "real-time" measurements made by the photo-acoustic, aethalometer and MAAP techniques have been described. In addition, the in situ aethalometer (seven-channel) results are compared with continuous integrating sphere uv-visible spectra to examine the angstrom absorption coefficient variance. These results will be briefly overviewed and the specific posters detailing these results will be highlighted highlighted. This work was performed as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City under the support of the Atmospheric Science Program. "This researchwas supported by the Office of Science (BER), U. S. Department of Energy, Grant No. DE-FG02-07ER64329.

  3. Distribution and Sources of Trace Gases and Aerosols in the Asian Summer Monsoon Anticyclone - Aircraft Observations and Model Simulations

    NASA Astrophysics Data System (ADS)

    Schlager, H.; Klausner, T.; Aufmhoff, H.; Baumann, R.; Gottschaldt, K. D.

    2015-12-01

    We report aircraft observations of trace gases and aerosols from recent field campaigns in the Asian summer monsoon anticyclone. Measurements were performed with the DLR Falcon and HALO aircraft at altitudes up to 15 km across the boundary of the anticyclone over the Arabian Sea during June, July and September conditions. Sharp gradients in chemical tracer mixing ratios were observed at the boundary of the anticyclone. In particular, sulfur dioxide and aerosols were enhanced inside the anticyclone. Ozone and carbon monoxide were enhanced or reduced in the anticyclone depending on the degree of in-mixing of air from the stratosphere inferred from observations of the stratospheric tracer hydrochloric acid. Backward trajectory analysis, tracer dispersion calculations, and simulations with the chemistry-climate model EMAC, nudged to the meteorological conditions of the measurements, were used to investigate the origin and transport of trace gases in and in the vicinity of the anticyclone. A chemistry-aerosol box model was used to simulate the formation of sulfate aerosol from sulfur dioxide inside the anticyclone uplifted by deep convection over northern India and in the Gulf of Bengal.

  4. Comparison of the performances of land use regression modelling and dispersion modelling in estimating small-scale variations in long-term air pollution concentrations in a Dutch urban area

    NASA Astrophysics Data System (ADS)

    Beelen, Rob; Voogt, Marita; Duyzer, Jan; Zandveld, Peter; Hoek, Gerard

    2010-11-01

    The performance of a Land Use Regression (LUR) model and a dispersion model (URBIS - URBis Information System) was compared in a Dutch urban area. For the Rijnmond area, i.e. Rotterdam and surroundings, nitrogen dioxide (NO 2) concentrations for 2001 were estimated for nearly 70 000 centroids of a regular grid of 100 × 100 m. A LUR model based upon measurements carried out on 44 sites from the Dutch national monitoring network and upon Geographic Information System (GIS) predictor variables including traffic intensity, industry, population and residential land use was developed. Interpolation of regional background concentration measurements was used to obtain the regional background. The URBIS system was used to estimate NO 2 concentrations using dispersion modelling. URBIS includes the CAR model (Calculation of Air pollution from Road traffic) to calculate concentrations of air pollutants near urban roads and Gaussian plume models to calculate air pollution levels near motorways and industrial sources. Background concentrations were accounted for using 1 × 1 km maps derived from monitoring and model calculations. Moderate agreement was found between the URBIS and LUR in calculating NO 2 concentrations ( R = 0.55). The predictions agreed well for the central part of the concentration distribution but differed substantially for the highest and lowest concentrations. The URBIS dispersion model performed better than the LUR model ( R = 0.77 versus R = 0.47 respectively) in the comparison between measured and calculated concentrations on 18 validation sites. Differences can be understood because of the use of different regional background concentrations, inclusion of rather coarse land use category industry as a predictor variable in the LUR model and different treatment of conversion of NO to NO 2. Moderate agreement was found between a dispersion model and a land use regression model in calculating annual average NO 2 concentrations in an area with multiple

  5. New Satellite Project Aerosol-UA: Remote Sensing of Aerosols in the Terrestrial Atmosphere

    NASA Technical Reports Server (NTRS)

    Milinevsky, G.; Yatskiv, Ya.; Degtyaryov, O.; Syniavskyi, I.; Mishchenko, Michael I.; Rosenbush, V.; Ivanov, Yu.; Makarov, A.; Bovchaliuk, A.; Danylevsky, V.; Sosonkin, M.; Moskalov, S.; Bovchaliuk, V; Lukenyuk, A.; Shymkiv, A.

    2016-01-01

    We discuss the development of the Ukrainian space project Aerosol-UA which has the following three main objectives: (1) to monitor the spatial distribution of key characteristics of terrestrial tropospheric and stratospheric aerosols; (2) to provide a comprehensive observational database enabling accurate quantitative estimates of the aerosol contribution to the energy budget of the climate system; and (3) quantify the contribution of anthropogenic aerosols to climate and ecological processes. The remote sensing concept of the project is based on precise orbital measurements of the intensity and polarization of sunlight scattered by the atmosphere and the surface with a scanning polarimeter accompanied by a wide-angle multispectral imager-polarimeter. Preparations have already been made for the development of the instrument suite for the Aerosol-UA project, in particular, of the multi-channel scanning polarimeter (ScanPol) designed for remote sensing studies of the global distribution of aerosol and cloud properties (such as particle size, morphology, and composition) in the terrestrial atmosphere by polarimetric and spectrophotometric measurements of the scattered sunlight in a wide range of wavelengths and viewing directions from which a scene location is observed. ScanPol is accompanied by multispectral wide-angle imager-polarimeter (MSIP) that serves to collect information on cloud conditions and Earths surface image. Various components of the polarimeter ScanPol have been prototyped, including the opto-mechanical and electronic assemblies and the scanning mirror controller. Preliminary synthetic data simulations for the retrieval of aerosol parameters over land surfaces have been performed using the Generalized Retrieval of Aerosol and Surface Properties (GRASP) algorithm. Methods for the validation of satellite data using ground-based observations of aerosol properties are also discussed. We assume that designing, building, and launching into orbit a multi

  6. An Analysis of AERONET Aerosol Absorption Properties and Classifications Representative of Aerosol Source Regions

    NASA Technical Reports Server (NTRS)

    Giles, David M.; Holben, Brent N.; Eck, Thomas F.; Sinyuk, Aliaksandr; Smirnov, Alexander; Slutsker, Ilya; Dickerson, R. R.; Thompson, A. M.; Schafer, J. S.

    2012-01-01

    Partitioning of mineral dust, pollution, smoke, and mixtures using remote sensing techniques can help improve accuracy of satellite retrievals and assessments of the aerosol radiative impact on climate. Spectral aerosol optical depth (tau) and single scattering albedo (omega (sub 0) ) from Aerosol Robotic Network (AERONET) measurements are used to form absorption [i.e., omega (sub 0) and absorption Angstrom exponent (alpha(sub abs))] and size [i.e., extinction Angstrom exponent (alpha(sub ext)) and fine mode fraction of tau] relationships to infer dominant aerosol types. Using the long-term AERONET data set (1999-2010), 19 sites are grouped by aerosol type based on known source regions to: (1) determine the average omega (sub 0) and alpha(sub abs) at each site (expanding upon previous work); (2) perform a sensitivity study on alpha(sub abs) by varying the spectral omega (sub 0); and (3) test the ability of each absorption and size relationship to distinguish aerosol types. The spectral omega (sub 0) averages indicate slightly more aerosol absorption (i.e., a 0.0 < delta omega (sub 0) <= 0.02 decrease) than in previous work and optical mixtures of pollution and smoke with dust show stronger absorption than dust alone. Frequency distributions of alpha(sub abs) show significant overlap among aerosol type categories and at least 10% of the alpha(sub abs) retrievals in each category are below 1.0. Perturbing the spectral omega (sub 0) by +/- 0.03 induces significant alpha(sub abs) changes from the unperturbed value by at least approx. +/- 0.6 for Dust, approx. +/-0.2 for Mixed, and approx. +/-0.1 for Urban/Industrial and Biomass Burning. The omega (sub 0)440nm and alpha(sub ext) 440-870nm relationship shows the best separation among aerosol type clusters, providing a simple technique for determining aerosol type from surface- and future space-based instrumentation.

  7. New satellite project Aerosol-UA: Remote sensing of aerosols in the terrestrial atmosphere

    NASA Astrophysics Data System (ADS)

    Milinevsky, G.; Yatskiv, Ya.; Degtyaryov, O.; Syniavskyi, I.; Mishchenko, M.; Rosenbush, V.; Ivanov, Yu.; Makarov, A.; Bovchaliuk, A.; Danylevsky, V.; Sosonkin, M.; Moskalov, S.; Bovchaliuk, V.; Lukenyuk, A.; Shymkiv, A.; Udodov, E.

    2016-06-01

    We discuss the development of the Ukrainian space project Aerosol-UA which has the following three main objectives: (1) to monitor the spatial distribution of key characteristics of terrestrial tropospheric and stratospheric aerosols; (2) to provide a comprehensive observational database enabling accurate quantitative estimates of the aerosol contribution to the energy budget of the climate system; and (3) quantify the contribution of anthropogenic aerosols to climate and ecological processes. The remote sensing concept of the project is based on precise orbital measurements of the intensity and polarization of sunlight scattered by the atmosphere and the surface with a scanning polarimeter accompanied by a wide-angle multispectral imager-polarimeter. Preparations have already been made for the development of the instrument suite for the Aerosol-UA project, in particular, of the multi-channel scanning polarimeter (ScanPol) designed for remote sensing studies of the global distribution of aerosol and cloud properties (such as particle size, morphology, and composition) in the terrestrial atmosphere by polarimetric and spectrophotometric measurements of the scattered sunlight in a wide range of wavelengths and viewing directions from which a scene location is observed. ScanPol is accompanied by multispectral wide-angle imager-polarimeter (MSIP) that serves to collect information on cloud conditions and Earth's surface image. Various components of the polarimeter ScanPol have been prototyped, including the opto-mechanical and electronic assemblies and the scanning mirror controller. Preliminary synthetic data simulations for the retrieval of aerosol parameters over land surfaces have been performed using the Generalized Retrieval of Aerosol and Surface Properties (GRASP) algorithm. Methods for the validation of satellite data using ground-based observations of aerosol properties are also discussed. We assume that designing, building, and launching into orbit a multi

  8. New understanding and quantification of the regime dependence of aerosol-cloud interaction for studying aerosol indirect effects

    DOE PAGESBeta

    Chen, Jingyi; Liu, Yangang; Zhang, Minghua; Peng, Yiran

    2016-02-28

    In this study, aerosol indirect effects suffer from large uncertainty in climate models and among observations. This study focuses on two plausible factors: regime dependence of aerosol-cloud interactions and the effect of cloud droplet spectral shape. We show, using a new parcel model, that combined consideration of droplet number concentration (Nc) and relative dispersion (ε, ratio of standard deviation to mean radius of the cloud droplet size distribution) better characterizes the regime dependence of aerosol-cloud interactions than considering Nc alone. Given updraft velocity (w), ε increases with increasing aerosol number concentration (Na) in the aerosol-limited regime, peaks in the transitionalmore » regime, and decreases with further increasing Na in the updraft-limited regime. This new finding further reconciles contrasting observations in literature and reinforces the compensating role of dispersion effect. The nonmonotonic behavior of ε further quantifies the relationship between the transitional Na and w that separates the aerosol- and updraft-limited regimes.« less

  9. Dispersibility of Amphibious Montmorillonite

    NASA Astrophysics Data System (ADS)

    Yeh, Meng-Heng; Hwang, Weng-Sing; Kuo, Wuei-Jueng

    2005-09-01

    The objective of this study is to develop a suitable method to convert hydrophilic montmorillonite into amphibious montmorillonite by replacing the sodium ions normally found in clay with poly(oxyethylene) (POE)-amide chlorite cations. Amphibious montmorillonite has a high d-spacing and good dispersion characteristics in many different types of solutions, including those having an intermediate hydrophilic lipophilic balance (HLB) value. Four different modifying cations are tested and X-ray diffraction analysis is performed to measure the resulting changes in the d-spacing of the MMT. Scanning electron microscopy is employed to investigate the morphology of the modified clays. A laser-doppler particle analyzer is used to measure the particle size of the clays in various solutions. Dobrat’s method is applied to calculate the dispersibility of each clay and Stoke’s law is used to evaluate the settling rate. The results indicate that the d-spacing of the POE-amide chlorite cation modified montmorillonite increases from 1.28 to 3.51 nm. The amphibious montmorillonite demonstrates good dispersion characteristics in eight commonly employed coating solutions with intermediate HLB values.

  10. Aerosol tests conducted at Aberdeen Proving Grounds MD.

    SciTech Connect

    Brockmann, John E.; Lucero, Daniel A.; Servantes, Brandon Lee; Hankins, Matthew Granholm

    2012-06-01

    Test data are reported that demonstrate the deposition from a spray dispersion system (Illinois Tool Works inductively charging rotary atomization nozzle) for application of decontamination solution to various surfaces in the passenger cabin of a Boeing 737 aircraft. The decontamination solution (EnviroTru) was tagged with a known concentration of fluorescein permitting determination of both airborne decontaminant concentration and surface deposited decontaminant solution so that the effective deposition rates and surface coverage could be determined and correlated with the amount of material sprayed. Six aerosol dispersion tests were conducted. In each test, aluminum foil deposition coupons were set out throughout the passenger area and the aerosol was dispersed. The aerosol concentration was measured with filter samplers as well as with optical techniques Average aerosol deposition ranged from 3 to 15 grams of decontamination solution per square meter. Some disagreement was observed between various instruments utilizing different measurement principles. These results demonstrate a potentially effective method to disperse decontaminant to interior surfaces of a passenger aircraft.

  11. Sources of Size Segregated Sulfate Aerosols in the Arctic Summer

    NASA Astrophysics Data System (ADS)

    Ghahremaninezhadgharelar, R.; Norman, A. L.; Abbatt, J.; Levasseur, M.

    2015-12-01

    Aerosols drive significant radiative forcing and affect Arctic climate. Despite the importance of these particles in Arctic climate change, there are some key uncertainties in the estimation of their effects and sources. Aerosols in six size fractions between <0.49 to 7.0 microns in diameter were collected on board the Canadian Coast Guard Ship (CCGS) Amundsen in the Arctic, during July 2014. A cascade impactor fitted to a high volume sampler was used for this study and was modified to permit collection of SO2 after aerosols were removed from the gas stream. The isotopic composition of sulfate aerosols and SO2 was measured and apportionment calculations have been performed to quantify the contribution of biogenic as well as anthropogenic sources to the growth of different aerosol size fractions in the atmosphere. The presence of sea salt sulfate aerosols was especially high in coarse mode aerosols as expected. The contribution of biogenic sulfate concentration in this study was higher than anthropogenic sulfate. Around 70% of fine aerosols (<0.49 μm) and 86% of SO2 were from biogenic sources. Concentrations of biogenic sulfate for fine aerosols, ranging from 18 to 625 ng/m3, were five times higher than total biogenic sulfate concentrations measured during Fall in the same region (Rempillo et al., 2011). A comparison of the isotope ratio for SO2 and fine aerosols offers a way to determine aerosol growth from local SO2 oxidation. For some samples, the values for SO2 and fine aerosols were close together suggesting the same source for SO2 and aerosol sulfur.Aerosols drive significant radiative forcing and affect Arctic climate. Despite the importance of these particles in Arctic climate change, there are some key uncertainties in the estimation of their effects and sources. Aerosols in six size fractions between <0.49 to 7.0 microns in diameter were collected on board the Canadian Coast Guard Ship (CCGS) Amundsen in the Arctic, during July 2014. A cascade impactor

  12. Determination of nine sensitizing disperse dyes in activated sludge by ultrasound-assisted liquid-liquid extraction-ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry.

    PubMed

    Zhou, Linjun; Shi, Lili; Liu, Jining; Lv, Fenglan; Xu, Yanhua

    2016-01-01

    A method was developed on the basis of ultrasound-assisted liquid-liquid extraction ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (ULLE-UPLC-ESI-MS/MS) to determine nine sensitizing disperse dyes in activated sludge. The samples were extracted using ULLE and separated through UPLC on an ACQUITY UPLCTM BEH C18 column with a gradient elution program of acetonitrile and acidified water (containing 2% acetonitrile, 0.2% formic acid, and 0.005 mol/L ammonium; pH 2.7) as the mobile phase. The samples were then identified and quantified through UPLC-ESI-MS/MS in a positive mode and multiple reaction monitoring. Results showed good linearity (10-1000 μg/L, 0.9934-0.9998), detection limit (0.08-2.17 μg/L), and quantification limit (0.27-7.38 μg/L) for the nine sensitizing disperse dyes, with recoveries ranging from 65.0 to 111.3%. The proposed method was applied to detect and determine the concentration of sensitizing disperse dyes in sludge samples obtained from various sewage treatment plants (six dyeing enterprises and one dye manufacturer). Three sensitizing disperse dyes were identified, and the lowest concentration detected was 10 μg/kg. PMID:26521175

  13. Migration of dispersive GPR data

    USGS Publications Warehouse

    Powers, M.H.; Oden, C.P.

    2004-01-01

    Electrical conductivity and dielectric and magnetic relaxation phenomena cause electromagnetic propagation to be dispersive in earth materials. Both velocity and attenuation may vary with frequency, depending on the frequency content of the propagating energy and the nature of the relaxation phenomena. A minor amount of velocity dispersion is associated with high attenuation. For this reason, measuring effects of velocity dispersion in ground penetrating radar (GPR) data is difficult. With a dispersive forward model, GPR responses to propagation through materials with known frequency-dependent properties have been created. These responses are used as test data for migration algorithms that have been modified to handle specific aspects of dispersive media. When either Stolt or Gazdag migration methods are modified to correct for just velocity dispersion, the results are little changed from standard migration. For nondispersive propagating wavefield data, like deep seismic, ensuring correct phase summation in a migration algorithm is more important than correctly handling amplitude. However, the results of migrating model responses to dispersive media with modified algorithms indicate that, in this case, correcting for frequency-dependent amplitude loss has a much greater effect on the result than correcting for proper phase summation. A modified migration is only effective when it includes attenuation recovery, performing deconvolution and migration simultaneously.

  14. Spatial distribution of atmospheric aerosol optical depth over Atlantic Ocean along the route of Russian Antarctic expeditions

    NASA Astrophysics Data System (ADS)

    Kabanov, Dmitry M.; Radionov, Vladimir F.; Sakerin, Sergey M.; Smirnov, Alexander

    2015-11-01

    During recent decade, Microtops and SPM portable sun photometers are used to perform annual measurements of aerosol optical depth (AOD) and water vapor content of the atmosphere over Atlantic Ocean along the route of the Russian Antarctic expeditions (RAE). The data accumulation has made it possible to analyze the specific features of the spatial distribution of spectral AOD of the atmosphere along eastern RAE route and identify six basic regions (latitudinal zones). The statistical characteristics of AOD in the identified oceanic regions in winter and spring periods are discussed. The estimates of finely and coarsely dispersed AOD components in different regions, as well as the interannual atmospheric AOD variations, are presented.

  15. Design of experiments and multivariate analysis for evaluation of reversed-phase high-performance liquid chromatography with charged aerosol detection of sucrose caprate regioisomers.

    PubMed

    Lie, Aleksander; Wimmer, Reinhard; Pedersen, Lars Haastrup

    2013-03-15

    The use of step-down gradient elution profiles to improve separation of sucrose caprate regioisomers was investigated as part of the development of a quantitative RP-HPLC analysis method with charged aerosol detection. The investigation was conducted using design-of-experiments methodology and evaluated by multivariate regression analysis. This approach was proven to be useful for systematic method development in HPLC analysis. The gradient elution profiles were described by four variables - two concentration variables and two duration variables. The regression analysis showed that the concentration variables had the most significant effects on retention times, both as individual terms and as part of variable interactions. All the regioisomers exhibited non-linear relationships between eluent acetonitrile concentration and retention time with similar curvatures. Kendall rank correlation coefficients confirmed that the curvatures of the regioisomer curves were highly dependent on each other. Charged aerosol detection provided a mass-sensitivity of 10-100 ng for the sucrose fatty acid ester regioisomers. Resolution deviation (RD) was defined as an aggregate objective function for evaluating the separation of three specific sucrose caprate regioisomers with similar elution properties substituted at positions 6-, 3- and 1'-, respectively. The investigation resulted in the development of elution strategies for separation and quantitative RP-HPLC analysis of regioisomers of sucrose caprate with all eight sucrose caprate regioisomers successfully identified. Thus, resolutions above the level of adequacy for quantification, R(s)≥1.0, were achieved for all regioisomers, both with isocratic and gradient elution strategies. For isocratic elutions, the best separation was achieved with eluent acetonitrile concentration 34%. Gradient elution resulted in a similar RD, but decreased the analysis time by 7-28%. For the gradient resulting in the most desirable combination of

  16. Infection of phytoplankton by aerosolized marine viruses.

    PubMed

    Sharoni, Shlomit; Trainic, Miri; Schatz, Daniella; Lehahn, Yoav; Flores, Michel J; Bidle, Kay D; Ben-Dor, Shifra; Rudich, Yinon; Koren, Ilan; Vardi, Assaf

    2015-05-26

    Marine viruses constitute a major ecological and evolutionary driving force in the marine ecosystems. However, their dispersal mechanisms remain underexplored. Here we follow the dynamics of Emiliania huxleyi viruses (EhV) that infect the ubiquitous, bloom-forming phytoplankton E. huxleyi and show that EhV are emitted to the atmosphere as primary marine aerosols. Using a laboratory-based setup, we showed that the dynamic of EhV aerial emission is strongly coupled to the host-virus dynamic in the culture media. In addition, we recovered EhV DNA from atmospheric samples collected over an E. huxleyi bloom in the North Atlantic, providing evidence for aerosolization of marine viruses in their natural environment. Decay rate analysis in the laboratory revealed that aerosolized viruses can remain infective under meteorological conditions prevailing during E. huxleyi blooms in the ocean, allowing potential dispersal and infectivity over hundreds of kilometers. Based on the combined laboratory and in situ findings, we propose that atmospheric transport of EhV is an effective transmission mechanism for spreading viral infection over large areas in the ocean. This transmission mechanism may also have an important ecological impact on the large-scale host-virus "arms race" during bloom succession and consequently the turnover of carbon in the ocean. PMID:25964340

  17. Infection of phytoplankton by aerosolized marine viruses

    PubMed Central

    Sharoni, Shlomit; Trainic, Miri; Schatz, Daniella; Lehahn, Yoav; Flores, Michel J.; Bidle, Kay D.; Ben-Dor, Shifra; Rudich, Yinon; Vardi, Assaf

    2015-01-01

    Marine viruses constitute a major ecological and evolutionary driving force in the marine ecosystems. However, their dispersal mechanisms remain underexplored. Here we follow the dynamics of Emiliania huxleyi viruses (EhV) that infect the ubiquitous, bloom-forming phytoplankton E. huxleyi and show that EhV are emitted to the atmosphere as primary marine aerosols. Using a laboratory-based setup, we showed that the dynamic of EhV aerial emission is strongly coupled to the host–virus dynamic in the culture media. In addition, we recovered EhV DNA from atmospheric samples collected over an E. huxleyi bloom in the North Atlantic, providing evidence for aerosolization of marine viruses in their natural environment. Decay rate analysis in the laboratory revealed that aerosolized viruses can remain infective under meteorological conditions prevailing during E. huxleyi blooms in the ocean, allowing potential dispersal and infectivity over hundreds of kilometers. Based on the combined laboratory and in situ findings, we propose that atmospheric transport of EhV is an effective transmission mechanism for spreading viral infection over large areas in the ocean. This transmission mechanism may also have an important ecological impact on the large-scale host–virus “arms race” during bloom succession and consequently the turnover of carbon in the ocean. PMID:25964340

  18. HOUSTON AEROSOL CHARACTERIZATION STUDY

    EPA Science Inventory

    An intensive field study of ambient aerosols was conducted in Houston between September 14 and October 14, 1978. Measurements at 12 sites were made using (1) two relocatable monitoring systems instrumented for aerosol and gaseous pollutants, (2) a network of high volume samplers ...

  19. Global Aerosol Observations

    Atmospheric Science Data Center

    2013-04-19

    ... atmosphere, directly influencing global climate and human health. Ground-based networks that accurately measure column aerosol amount and ... being used to improve Air Quality Models and for regional health studies. To assess the human-health impact of chronic aerosol exposure, ...

  20. Direct Aerosol Forcing Uncertainty

    DOE Data Explorer

    Mccomiskey, Allison

    2008-01-15

    Understanding sources of uncertainty in aerosol direct radiative forcing (DRF), the difference in a given radiative flux component with and without aerosol, is essential to quantifying changes in Earth's radiation budget. We examine the uncertainty in DRF due to measurement uncertainty in the quantities on which it depends: aerosol optical depth, single scattering albedo, asymmetry parameter, solar geometry, and surface albedo. Direct radiative forcing at the top of the atmosphere and at the surface as well as sensitivities, the changes in DRF in response to unit changes in individual aerosol or surface properties, are calculated at three locations representing distinct aerosol types and radiative environments. The uncertainty in DRF associated with a given property is computed as the product of the sensitivity and typical measurement uncertainty in the respective aerosol or surface property. Sensitivity and uncertainty values permit estimation of total uncertainty in calculated DRF and identification of properties that most limit accuracy in estimating forcing. Total uncertainties in modeled local diurnally averaged forcing range from 0.2 to 1.3 W m-2 (42 to 20%) depending on location (from tropical to polar sites), solar zenith angle, surface reflectance, aerosol type, and aerosol optical depth. The largest contributor to total uncertainty in DRF is usually single scattering albedo; however decreasing measurement uncertainties for any property would increase accuracy in DRF. Comparison of two radiative transfer models suggests the contribution of modeling error is small compared to the total uncertainty although comparable to uncertainty arising from some individual properties.

  1. Portable Aerosol Contaminant Extractor

    DOEpatents

    Carlson, Duane C.; DeGange, John J.; Cable-Dunlap, Paula

    2005-11-15

    A compact, portable, aerosol contaminant extractor having ionization and collection sections through which ambient air may be drawn at a nominal rate so that aerosol particles ionized in the ionization section may be collected on charged plate in the collection section, the charged plate being readily removed for analyses of the particles collected thereon.

  2. Investigation of aerosol optical properties for remote sensing through DRAGON (distributed regional aerosol gridded observation networks) campaign in Korea

    NASA Astrophysics Data System (ADS)

    Lim, Jae-Hyun; Ahn, Joon Young; Park, Jin-Soo; Hong, You-Deok; Han, Jin-Seok; Kim, Jhoon; Kim, Sang-Woo

    2014-11-01

    Aerosols in the atmosphere, including dust and pollutants, scatters/absorbs solar radiation and change the microphysics of clouds, thus influencing the Earth's energy budget, climate, air quality, visibility, agriculture and water circulation. Pollutants have also been reported to threaten the human health. The present research collaborated with the U.S. NASA and the U.S. Aerosol Robotic Network (AERONET) is to study the aerosol characteristics in East Asia and improve the long-distance transportation monitoring technology by analyzing the observations of aerosol characteristics in East Asia during Distributed Regional Aerosol Gridded Observation Networks (DRAGON) Campaign (March 2012-May 2012). The sun photometers that measure the aerosol optical characteristics were placed evenly throughout the Korean Peninsula and concentrated in Seoul and the metropolitan area. Observation data are obtained from the DRAGON campaign and the first year (2012) observation data (aerosol optical depth and aerosol spatial distribution) are analyzed. Sun photometer observations, including aerosol optical depth (AOD), are utilized to validate satellite observations from Geostationary Ocean Color Imager (GOCI) and Moderate Resolution Imaging Spectroradiometer (MODIS). Additional analysis is performed associated with the Northeast Asia, the Korean Peninsula in particular, to determine the spatial distribution of the aerosol.

  3. Information Content of Aerosol Retrievals in the Sunglint Region

    NASA Technical Reports Server (NTRS)

    Ottaviani, M.; Knobelspiesse, K.; Cairns, B.; Mishchenko, M.

    2013-01-01

    We exploit quantitative metrics to investigate the information content in retrievals of atmospheric aerosol parameters (with a focus on single-scattering albedo), contained in multi-angle and multi-spectral measurements with sufficient dynamical range in the sunglint region. The simulations are performed for two classes of maritime aerosols with optical and microphysical properties compiled from measurements of the Aerosol Robotic Network. The information content is assessed using the inverse formalism and is compared to that deriving from observations not affected by sunglint. We find that there indeed is additional information in measurements containing sunglint, not just for single-scattering albedo, but also for aerosol optical thickness and the complex refractive index of the fine aerosol size mode, although the amount of additional information varies with aerosol type.

  4. Program Models A Laser Beam Focused In An Aerosol Spray

    NASA Technical Reports Server (NTRS)

    Barton, J. P.

    1996-01-01

    Monte Carlo analysis performed on packets of light. Program for Analysis of Laser Beam Focused Within Aerosol Spray (FLSPRY) developed for theoretical analysis of propagation of laser pulse optically focused within aerosol spray. Applied for example, to analyze laser ignition arrangement in which focused laser pulse used to ignite liquid aerosol fuel spray. Scattering and absorption of laser light by individual aerosol droplets evaluated by use of electromagnetic Lorenz-Mie theory. Written in FORTRAN 77 for both UNIX-based computers and DEC VAX-series computers. VAX version of program (LEW-16051). UNIX version (LEW-16065).

  5. Dyphylline aerosol can induce bronchospasm in human asthmatics.

    PubMed

    Lawyer, C; Auer, S; Brottem, J; Bardana, E; Hirshman, C; Lynn, R; Downes, H

    1982-01-01

    Dihydroxypropyl theophylline (dyphylline) was administered by aerosol in a single dose of 250 mg aerosolized over five minutes to two asthmatic volunteers and in a single dose of 375 mg aerosolized over ten minutes to two other asthmatic volunteers. Serial spirometry was then performed. Marked bronchospasm occurred within ten minutes in two of the subjects, and developed more slowly in another. One subject demonstrated no significant change. Aerosolized dyphylline solution was not an effective bronchodilator, using the methods described in this study. PMID:6957527

  6. Stratospheric aerosols in the intertropical convergence zone, Panama Canal zone

    NASA Technical Reports Server (NTRS)

    Farlow, N. H.; Ferry, G. V.; Lem, H. Y.; Hayes, D. M.

    1979-01-01

    To investigate whether injection sources of the stratospheric aerosol layer could be detected in the tropical stratosphere, an examination of the aerosol vertical and horizontal size distribution around the Intertropical Convergence Zone (ITCZ) at the Panama Canal Zone was performed during the summer of 1977. By comparing these data with similar measurements in temperate and polar regions, it was hoped to discover variations in particle size that would indicate whether a young aerosol is forming and entering the stratosphere at the ITCZ; where the aerosol matures; and finally, where it reenters the troposphere. The methods used in the investigations and the results obtained from the analyses are described.

  7. Application of dispersive liquid–liquid microextraction and reversed phase-high performance liquid chromatography for the determination of two fungicides in environmental water samples

    PubMed Central

    Cheng, Jing; Zhou, Yiwen; Zuo, Mei; Dai, Liping; Guo, Xiaojie

    2010-01-01

    Dispersive liquid–liquid microextraction (DLLME) has been developed for the extraction and preconcentration of diethofencarb (DF) and pyrimethanil (PM) in environmental water. In the method, a suitable mixture of extraction solvent (50 μL carbon tetrachloride) and dispersive solvent (0.75 mL acetonitrile) are injected into the aqueous samples (5.00 mL) and the cloudy solution is observed. After centrifugation, the enriched analytes in the sediment phase were determined by HPLC-VWD. Different influencing factors, such as the kind and volume of extraction and dispersive solvent, extraction time and salt effect were investigated. Under the optimum conditions, the enrichment factors for DF and PM were both 108 and the limit of detection were 0.021 ng mL−1 and 0.015 ng mL−1, respectively. The linear ranges were 0.08–400 ng mL−1 for DF and 0.04–200 ng mL−1 for PM. The relative standard deviation (RSDs) were both almost at 6.0% (n = 6). The relative recoveries from samples of environmental water were from the range of 87.0 to 107.2%. Compared with other methods, DLLME is a very simple, rapid, sensitive (low limit of detection) and economical (only 5 mL volume of sample) method. PMID:20862191

  8. Cardiogenic mixing increases aerosol deposition in the human lung in the absence of gravity

    PubMed Central

    Prisk, G. Kim; Sá, Rui Carlos; Darquenne, Chantal

    2012-01-01

    Rationale Exposure to extraterrestrial dusts is an almost inevitable consequence of any proposed planetary exploration. Previous studies in humans showed reduced deposition in low-gravity compared with normal gravity (1G). However, the reduced sedimentation means that fewer particles deposit in the airways, increasing the number of particles transported to the lung periphery where they eventually deposit albeit at a smaller rate than in 1G. In this study, we determined the role that gravity and other mechanisms such as cardiogenic mixing play in peripheral lung deposition during breath holds. Methods Eight healthy subjects inhaled boluses of 0.5 μm-diameter particles to penetration volumes (Vp) of 300 and 1200ml that were followed by breath holds of up to 10 sec. Tests were performed in 1G and during short periods of microgravity (μG) aboard the NASA Microgravity Research Aircraft. Aerosol deposition and dispersion were calculated from these data. Results Results show that, for both Vp, deposition in 1G was significantly higher than in μG. In contrast, while dispersion was significantly higher in 1G compared to μG at Vp=1200ml, there was no significant gravitational effect on dispersion at Vp=300ml. Finally, for each G level and Vp, deposition and dispersion significantly increased with increasing breath-hold time. Conclusion The most important finding of this study is that, even in the absence of gravity, aerosol deposition in the lung periphery increased with increasing residence time. Because the particles used in this study were too large to be significantly affected by Brownian diffusion, the increase in deposition is likely due to cardiogenic motion effects. PMID:23976801

  9. An improved method for retrieving nighttime aerosol optical thickness from the VIIRS Day/Night Band

    NASA Astrophysics Data System (ADS)

    McHardy, T. M.; Zhang, J.; Reid, J. S.; Miller, S. D.; Hyer, E. J.; Kuehn, R. E.

    2015-11-01

    Using Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) data, a method, dubbed the "variance method", is developed for retrieving nighttime aerosol optical thickness (τ) values through the examination of the dispersion of radiance values above an artificial light source. Based on the improvement of a previous algorithm, this updated method derives a semi-quantitative indicator of nighttime τ using artificial light sources. Nighttime τ retrievals from the newly developed method are inter-compared with an interpolated value from late afternoon and early morning ground observations from four AErosol RObotic NETwork (AERONET) sites as well as column-integrated τ from one High Spectral Resolution Lidar (HSRL) site at Huntsville, AL, during the NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign, providing full diel coverage. Sensitivity studies are performed to examine the effects of lunar illumination on VIIRS τ retrievals made via the variance method, revealing that lunar contamination may have a smaller impact than previously thought; however, the small sample size of this study limits the conclusiveness thus far. VIIRS τ retrievals yield a coefficient of determination (r2) of 0.60 and a root-mean-squared error (RMSE) of 0.18 when compared against straddling daytime-averaged AERONET τ values. Preliminary results suggest that artificial light sources can be used for estimating regional and global nighttime aerosol distributions in the future.

  10. A rotating, bluff-body disc for reduced variability in wind tunnel aerosol studies

    PubMed Central

    Koehler, Kirsten A.; Anthony, T. Renee; van Dyke, Michael; Volckens, John

    2016-01-01

    A rotating bluff-body disc (RBD) was developed to reduce spatiotemporal variability associated with sampling supermicron aerosol in low-velocity wind tunnels. The RBD is designed to rotate eight personal aerosol samplers around a circular path in a forward-facing plane aligned with the wind tunnel cross section. Rotation of the RBD allows each sampler to traverse an identical path about the wind tunnel cross section, which reduces the effects of spatial heterogeneity associated with dispersing supermicron aerosol in low-velocity wind tunnels. Samplers are positioned on the face of the RBD via sampling ports, which connect to an air manifold on the back of the disc. Flow through each sampler was controlled with a critical orifice or needle valve, allowing air to be drawn through the manifold with a single pump. A metal tube, attached to this manifold, serves as both the axis of rotation and the flow conduction path (between the samplers and the vacuum source). Validation of the RBD was performed with isokinetic samplers and 37-mm cassettes. For facing-the-wind tests, the rotation of the RBD significantly decreased intra-sampler variability when challenged with particle diameters from 1 to 100 μm. The RBD was then employed to determine the aspiration efficiency of Institute of Occupational Medicine (IOM) personal samplers under a facing-the-wind condition. Operation of IOM samplers on the RBD reduced the between-sampler variability for all particle sizes tested. PMID:21097990

  11. Utilization of near real-time satellite data in atmospheric transport and dispersion modeling applications

    NASA Astrophysics Data System (ADS)

    Nair, U. S.; Christopher, S. A.; Wu, Y.; Yang, E.; Keiser, K.

    2010-12-01

    Prior studies show that satellite derived land and aerosols products may be utilized to improve numerical model predictions of atmospheric transport and dispersion. Satellite derived smoke emissions can be effectively utilized in numerical modeling of smoke transport. Satellite derived aerosol optical thickness (AOT) provide an effective constraint for the column loading in aerosol transport models. Land surface heterogeneity has substantial impact on mesoscale and small scale atmospheric dispersion. Satellite derived land products such as albedo and leaf area index provide an effective constraint for land surface heterogeneity. Utilization of NASA MODIS land and aerosol products in multiple applications related to atmospheric dispersion, nutrient deposition and air quality modeling will be discussed. These applications are developed for near-real time use in a decision support related to emergency and environmental management in the State of Alabama. Experiences and lessons learned form the development of these applications will also be discussed.

  12. Comparison of Aerosol Classification from Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Omar, A. H.; Hostetler, C. A.; Hair, J. W.; Rogers, R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.

    2012-12-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft has acquired large datasets of aerosol extinction (532nm), backscatter (532 and 1064nm), and depolarization (532 and 1064nm) profiles during 349 science flights in 19 field missions across North America since 2006. The extinction-to-backscatter ratio ("lidar ratio"), aerosol depolarization ratios, and backscatter color ratio measurements from HSRL-1 are scale-invariant parameters that depend on aerosol type but not concentration. These four aerosol intensive parameters are combined to qualitatively classify HSRL aerosol measurements into eight separate composition types. The classification methodology uses models formed from "training cases" with known aerosol type. The remaining measurements are then compared with these models using the Mahalanobis distance. Aerosol products from the CALIPSO satellite include aerosol type information as well, which is used as input to the CALIPSO aerosol retrieval. CALIPSO aerosol types are inferred using a mix of aerosol loading-dependent parameters, estimated aerosol depolarization, and location, altitude, and surface type information. The HSRL instrument flies beneath the CALIPSO satellite orbit track, presenting the opportunity for comparisons between the HSRL aerosol typing and the CALIPSO Vertical Feature Mask Aerosol Subtype product, giving insight into the performance of the CALIPSO aerosol type algorithm. We find that the aerosol classification from the two instruments frequently agree for marine aerosols and pure dust, and somewhat less frequently for pollution and smoke. In addition, the comparison suggests that the CALIPSO polluted dust type is overly inclusive, encompassing cases of dust combined with marine aerosol as well as cases without much evidence of dust. Qualitative classification of aerosol type combined with quantitative profile measurements of aerosol backscatter and extinction has many useful

  13. Atmospheric aerosol and Doppler lidar studies

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeff; Bowdle, D. A.; Srivastava, V.; Jarzembski, M.; Cutten, D.; Mccaul, E. W., Jr.

    1991-01-01

    Experimental and theoretical studies were performed of atmospheric aerosol backscatter and atmospheric dynamics with Doppler lidar as a primary tool. Activities include field and laboratory measurement and analysis efforts. The primary focus of activities related to understanding aerosol backscatter is the GLObal Backscatter Experiment (GLOBE) program. GLOBE is a multi-element effort designed toward developing a global aerosol model to describe tropospheric clean background backscatter conditions that Laser Atmospheric Wind Sounder (LAWS) is likely to encounter. Two survey missions were designed and flown in the NASA DC-8 in November 1989 and May to June 1990 over the remote Pacific Ocean, a region where backscatter values are low and where LAWS wind measurements could make a major contribution. The instrument complement consisted of pulsed and continuous-wave (CW) CO2 gas and solid state lidars measuring aerosol backscatter, optical particle counters measuring aerosol concentration, size distribution, and chemical composition, a filter/impactor system collecting aerosol samples for subsequent analysis, and integrating nephelometers measuring visible scattering coefficients. The GLOBE instrument package and survey missions were carefully planned to achieve complementary measurements under clean background backscatter conditions.

  14. Simulation of Climate Forcing by Aerosols

    SciTech Connect

    Ghan, Steven J.; Bian, Xindi; Chapman, Elaine G.; Easter, Richard C.; Fann, George I.; Kothari, Suraj C.; Zaveri, Rahul A.; Zhang, Yang

    2004-05-03

    The largest source of uncertainty in estimates of the radiative forcing governing climate change is in the radiative forcing due to anthropogenic aerosols. Current estimates of the global mean of the aerosol radiative forcing range from –0.3 to –3.0 watts per square meter (Wm-2 ) which is opposite in sign and possibly comparable in magnitude to the +2 Wm-2 forcing due to increasing greenhouse gases. We have developed a global aerosol and climate modeling system that provides arguably the most detailed treatment of aerosols and their impact on the planetary radiation balance of any model, but our estimates of radiative forcing have been hindered by our lack of access to high performance computing resources. We propose to use the MSCF to conduct a series of simulations with and without emissions of a variety of aerosol particles and aerosol precursors. These extensive simulations will enable us to produce much more refined estimates of the impact of anthropogenic emissions on radiative forcing of climate change. To take full advantage of the parallelism available on the MSCF MPP1, we will apply the Global Array Toolkit to dynamically load balance the reactive chemistry component of our model. We will adapt our modifications of the serial NCAR Community Climate Model CCM2 to the parallel NCAR CCM3.10.

  15. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1996-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

  16. Sensitivity of numerical dispersion modeling to explosive source parameters

    SciTech Connect

    Baskett, R.L. ); Cederwall, R.T. )

    1991-02-13

    The calculation of downwind concentrations from non-traditional sources, such as explosions, provides unique challenges to dispersion models. The US Department of Energy has assigned the Atmospheric Release Advisory Capability (ARAC) at the Lawrence Livermore National Laboratory (LLNL) the task of estimating the impact of accidental radiological releases to the atmosphere anywhere in the world. Our experience includes responses to over 25 incidents in the past 16 years, and about 150 exercises a year. Examples of responses to explosive accidents include the 1980 Titan 2 missile fuel explosion near Damascus, Arkansas and the hydrogen gas explosion in the 1986 Chernobyl nuclear power plant accident. Based on judgment and experience, we frequently estimate the source geometry and the amount of toxic material aerosolized as well as its particle size distribution. To expedite our real-time response, we developed some automated algorithms and default assumptions about several potential sources. It is useful to know how well these algorithms perform against real-world measurements and how sensitive our dispersion model is to the potential range of input values. In this paper we present the algorithms we use to simulate explosive events, compare these methods with limited field data measurements, and analyze their sensitivity to input parameters. 14 refs., 7 figs., 2 tabs.

  17. The interaction of bromine with micron and submicron aerosols.

    PubMed

    Spatola, J A; Gentry, J W

    1980-11-01

    This study was undertaken to gain a better understanding of the reactions of aerosols with gases and vapors. The experimental system was designed in which both phases were dispersed. A collision-type nebulizer was used to generate monodisperse aerosols of 0.234, 0.500, 0.804, 1.101 and 2.020 microns diameter. Bromine concentrations of 100 and 200 ppm were produced to interact with the aerosolS. A light-scattering optical particle counter was used to determine the particle number concentration. Reacted aerosol collected on Teflon filters was analyzed by energy-dispersive x-ray fluorescence. Two temperature regimes were selected: approximately 26 degrees C and 60 degrees C. Separate runs were also conducted for the extreme case of zero curvature using 25 microns thick polystyrene sheet. Data generated from this study show a strong dependence of bromine levels on particle size. As the particle size increased, the amount of bromine per particle (ng Br/particle) also increased. However, on a weight-to-weight basis (ng Br/ng aerosol), the amount of bromine was found to increase with decreasing particle size. The concentration dependence on particle diameter was more strongly associated with values between d2 and d3. This dependence, together with other experimental data, supports a shrinking-unreacted core physical model for the actual reaction. When Br2 concentration or reaction temperature was increased, higher levels of bromine resulted in the aerosol. Runs where both temperature and concentration were increased showed lower levels of bromine than with an increase in either variable. One possible explanation is that the relative rates of reaction on the surface of the particle and diffusion through the reacted shell may be the influencing factors. Brominated polystyrene sheet material showed substantially lower bromine levels than the aerosols. PMID:7457368

  18. Comparison of coliphage and bacterial aerosols at a wastewater spray irrigation site.

    PubMed

    Bausum, H T; Schaub, S A; Kenyon, K F; Small, M J

    1982-01-01

    Microbiological aerosols were measured on a spray irrigation site at Fort Huachuca, Ariz. Indigenous bacteria and tracer bacteriophage were sampled from sprays of chlorinated and unchlorinated secondary-treatment wastewaters during day and night periods. Aerosol dispersal and downwind migration were determined. Bacterial and coliphage f2 aerosols were sampled by using Andersen viable type stacked-sieve and high-volume electrostatic precipitator samplers. Bacterial standard plate counts averaged 2.4 x 10(5) colony-forming units per ml in unchlorinated effluents. Bacterial aerosols reached 500 bacteria per m3 at 152 m downwind and 10,500 bacteria per m3 at 46m. Seeded coliphage f2 averaged 4.0 x 10(5) plaque-forming units per ml in the effluent and were detected 563 m downwind. Downwind microbial aerosol levels were somewhat enhanced by nighttime conditions. The median aerodynamic particle size of the microbial aerosols was approximately 5.0 micrometer. Chlorination reduced wastewater bacterial levels 99.97% and reduced aerosol concentrations to near background levels; coliphage f2 was reduced only 95.4% in the chlorinated effluent and was readily measured 137 m downwind. Microbiological source strength an meteorological data were used in conjunction with a dispersion model to generate mathematical predictions of aerosol strength at various sampler locations. The mean calculated survival of aerosolized bacteria (standard plate count) in the range 46 to 76 m downwind was 5.2%, and that of coliphage f2 was 4.3 %. PMID:7055376

  19. Analysis of Atmospheric Aerosol Data Sets and Application of Radiative Transfer Models to Compute Aerosol Effects

    NASA Technical Reports Server (NTRS)

    Schmid, Beat; Bergstrom, Robert W.; Redemann, Jens

    2002-01-01

    This report is the final report for "Analysis of Atmospheric Aerosol Data Sets and Application of Radiative Transfer Models to Compute Aerosol Effects". It is a bibliographic compilation of 29 peer-reviewed publications (published, in press or submitted) produced under this Cooperative Agreement and 30 first-authored conference presentations. The tasks outlined in the various proposals are listed below with a brief comment as to the research performed. Copies of title/abstract pages of peer-reviewed publications are attached.

  20. Dispersal Timing: Emigration of Insects Living in Patchy Environments.

    PubMed

    Lakovic, Milica; Poethke, Hans-Joachim; Hovestadt, Thomas

    2015-01-01

    Dispersal is a life-history trait affecting dynamics and persistence of populations; it evolves under various known selective pressures. Theoretical studies on dispersal typically assume 'natal dispersal', where individuals emigrate right after birth. But emigration may also occur during a later moment within a reproductive season ('breeding dispersal'). For example, some female butterflies first deposit eggs in their natal patch before migrating to other site(s) to continue egg-laying there. How breeding compared to natal dispersal influences the evolution of dispersal has not been explored. To close this gap we used an individual-based simulation approach to analyze (i) the evolution of timing of breeding dispersal in annual organisms, (ii) its influence on dispersal (compared to natal dispersal). Furthermore, we tested (iii) its performance in direct evolutionary contest with individuals following a natal dispersal strategy. Our results show that evolution should typically result in lower dispersal under breeding dispersal, especially when costs of dispersal are low and population size is small. By distributing offspring evenly across two patches, breeding dispersal allows reducing direct sibling competition in the next generation whereas natal dispersal can only reduce trans-generational kin competition by producing highly dispersive offspring in each generation. The added benefit of breeding dispersal is most prominent in patches with small population sizes. Finally, the evolutionary contests show that a breeding dispersal strategy would universally out-compete natal dispersal. PMID:26132493

  1. Development of a dispersive liquid-liquid microextraction method for the determination of fluoroquinolones in chicken liver by high performance liquid chromatography.

    PubMed

    Moema, D; Nindi, M M; Dube, S

    2012-06-12

    A simple and cost effective sample pre-treatment method, dispersive liquid-liquid microextraction (DLLME), has been developed for the extraction of six fluoroquinolones (FQs) from chicken liver samples. Clean DLLME extracts were analyzed for fluoroquinolones using liquid chromatography with diode array detection (LC-DAD). Parameters such as type and volume of disperser solvent, type and volume of extraction solvent, concentration and composition of phosphoric acid in the disperser solvent and pH were optimized. Linearity in the concentration range of 30-500 μg kg(-1) was obtained with regression coefficients ranging from 0.9945 to 0.9974. Intra-day repeatability expressed as % RSD was between 4 and 7%. The recoveries determined in spiked blank chicken livers at three concentration levels (i.e. 50, 100 and 300 μg kg(-1)) ranged from 83 to 102%. LODs were between 5 and 19 μg kg(-1) while LOQs ranged between 23 and 62 μg kg(-1). All of the eight chicken liver samples obtained from the local supermarkets were found to contain at least one type of fluoroquinolone with enrofloxacin being the most commonly detected. Only one sample had four fluoroquinolone antibiotics (ciprofloxacin, difloxacin, enrofloxacin, norfloxacin). Norfloxacin which is unlicensed for use in South Africa was also detected in three of the eight chicken liver samples analyzed. The concentration levels of all FQs antibiotics in eight samples ranged from 8.8 to 35.3 μg kg(-1), values which are lower than the South African stipulated maximum residue limits (MRL). PMID:22632048

  2. Measurements of atmospheric aerosol vertical distributions above Svalbard, Norway, using unmanned aerial systems (UAS)

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P. K.; Johnson, J. E.; Corless, A.; Brechtel, F. J.; Stalin, S. E.; Meinig, C.; Burkhart, J. F.

    2013-08-01

    Atmospheric aerosol vertical distributions were measured above Svalbard, Norway, in April 2011 during the Cooperative Investigation of Climate-Cryosphere Interactions campaign (CICCI). Measurements were made of the particle number concentration and the aerosol light absorption coefficient at three wavelengths. A filter sample was collected on each flight at the altitude of maximum particle number concentration. The filters were analyzed for major anions and cations. The aerosol payload was flown in a NOAA/PMEL MANTA Unmanned Aerial System (UAS). A total of 18 flights were flown during the campaign totaling 38 flight hours. The data show frequent aerosol layers aloft with high particle number concentration (1000 cm-3) and enhanced aerosol light absorption (1 Mm-1). Air mass histories of these aerosol layers were assessed using FLEXPART particle dispersion modeling. The data contribute to an assessment of sources of BC to the Arctic and potential climate impacts.

  3. Measurements of atmospheric aerosol vertical distributions above Svalbard, Norway using unmanned aerial systems (UAS)

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P. K.; Johnson, J. E.; Corless, A.; Brechtel, F. J.; Stalin, S. E.; Meinig, C.; Burkhart, J. F.

    2013-03-01

    Atmospheric aerosol vertical distributions were measured above Svalbard, Norway in April 2011 during the Cooperative Investigation of Climate-Cryosphere Interactions campaign (CICCI). Measurements were made of the particle number concentration and the aerosol light absorption coefficient at three wavelengths. A filter sample was collected on each flight at the altitude of maximum particle number concentration. The filters were analyzed for major anions and cations. The aerosol payload was flown in a NOAA/PMEL MANTA Unmanned Aerial System (UAS). A total of 18 flights were flown during the campaign totaling 38 flight hours. The data show frequent aerosol layers aloft with high particle number concentration (1000 cm-3 and enhanced aerosol light absorption (1 Mm-1). Air mass histories of these aerosol layers were assessed using FLEXPART particle dispersion modeling. The data contribute to an assessment of sources of BC to the Arctic and potential climate impacts.

  4. Sugars in Antarctic aerosol

    NASA Astrophysics Data System (ADS)

    Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

    2015-10-01

    The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the "Mario Zucchelli" coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

  5. Initial steps of aerosol growth

    NASA Astrophysics Data System (ADS)

    Kulmala, M.; Laakso, L.; Lehtinen, K. E. J.; Riipinen, I.; Dal Maso, M.; Anttila, T.; Kerminen, V.-M.; Hõrrak, U.; Vana, M.; Tammet, H.

    2004-12-01

    The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent - mainly condensational - growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm (diameter) in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhanced growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

  6. Initial steps of aerosol growth

    NASA Astrophysics Data System (ADS)

    Kulmala, O.; Laakso, L.; Lehtinen, K. E. J.; Riipinen, I.; Dal Maso, M.; Anttila, T.; Kerminen, V.-M.; Hõrrak, U.; Vana, M.; Tammet, H.

    2004-09-01

    The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent - mainly condensational - growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhance growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

  7. Simulation modeling of anthrax spore dispersion in a bioterrorism incident.

    PubMed

    Reshetin, Vladimir P; Regens, James L

    2003-12-01

    Recent events have increased awareness of the risk posed by terrorist attacks. Bacillus anthracis has resurfaced in the 21st century as a deadly agent of bioterrorism because of its potential for causing massive civilian casualties. This analysis presents the results of a computer simulation of the dispersion of anthrax spores in a typical 50-story, high-rise building after an intentional release during a bioterrorist incident. The model simulates aerosol dispersion in the case of intensive, small-scale convection, which equalizes the concentration of anthrax spores over the building volume. The model can be used to predict the time interval required for spore dispersion throughout a building after a terrorist attack in a high-rise building. The analysis reveals that an aerosol release of even a relatively small volume of anthrax spores during a terrorist incident has the potential to quickly distribute concentrations that are infectious throughout the building. PMID:14641889

  8. AeroCom INSITU Project: Comparing modeled and measured aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Andrews, Elisabeth; Schmeisser, Lauren; Schulz, Michael; Fiebig, Markus; Ogren, John; Bian, Huisheng; Chin, Mian; Easter, Richard; Ghan, Steve; Kokkola, Harri; Laakso, Anton; Myhre, Gunnar; Randles, Cynthia; da Silva, Arlindo; Stier, Phillip; Skeie, Ragnehild; Takemura, Toshihiko; van Noije, Twan; Zhang, Kai

    2016-04-01

    AeroCom, an open international collaboration of scientists seeking to improve global aerosol models, recently initiated a project comparing model output to in-situ, surface-based measurements of aerosol optical properties. The model/measurement comparison project, called INSITU, aims to evaluate the performance of a suite of AeroCom aerosol models with site-specific observational data in order to inform iterative improvements to model aerosol modules. Surface in-situ data has the unique property of being traceable to physical standards, which is an asset in accomplishing the overall goal of bettering the accuracy of aerosols processes and the predicative capability of global climate models. Here we compare dry, in-situ aerosol scattering and absorption data from ~75 surface, in-situ sites from various global aerosol networks (including NOAA, EUSAAR/ACTRIS and GAW) with a simulated optical properties from a suite of models participating in the AeroCom project. We report how well models reproduce aerosol climatologies for a variety of time scales, aerosol characteristics and behaviors (e.g., aerosol persistence and the systematic relationships between aerosol optical properties), and aerosol trends. Though INSITU is a multi-year endeavor, preliminary phases of the analysis suggest substantial model biases in absorption and scattering coefficients compared to surface measurements, though the sign and magnitude of the bias varies with location. Spatial patterns in the biases highlight model weaknesses, e.g., the inability of models to properly simulate aerosol characteristics at sites with complex topography. Additionally, differences in modeled and measured systematic variability of aerosol optical properties suggest that some models are not accurately capturing specific aerosol behaviors, for example, the tendency of in-situ single scattering albedo to decrease with decreasing aerosol extinction coefficient. The endgoal of the INSITU project is to identify specific

  9. Indirect and semi-direct aerosol campaign: The impact of Arctic aerosols on clouds

    DOE PAGESBeta

    McFarquhar, Greg M.; Ghan, Steven; Verlinde, Johannes; Korolev, Alexei; Strapp, J. Walter; Schmid, Beat; Tomlinson, Jason M.; Wolde, Menqistu; Brooks, Sarah D.; Cziczo, Dan; et al

    2011-02-01

    A comprehensive dataset of microphysical and radiative properties of aerosols and clouds in the boundary layer in the vicinity of Barrow, Alaska, was collected in April 2008 during the Indirect and Semi-Direct Aerosol Campaign (ISDAC). ISDAC's primary aim was to examine the effects of aerosols, including those generated by Asian wildfires, on clouds that contain both liquid and ice. ISDAC utilized the Atmospheric Radiation Measurement Pro- gram's permanent observational facilities at Barrow and specially deployed instruments measuring aerosol, ice fog, precipitation, and radiation. The National Research Council of Canada Convair-580 flew 27 sorties and collected data using an unprecedented 41more » stateof- the-art cloud and aerosol instruments for more than 100 h on 12 different days. Aerosol compositions, including fresh and processed sea salt, biomassburning particles, organics, and sulfates mixed with organics, varied between flights. Observations in a dense arctic haze on 19 April and above, within, and below the single-layer stratocumulus on 8 and 26 April are enabling a process-oriented understanding of how aerosols affect arctic clouds. Inhomogeneities in reflectivity, a close coupling of upward and downward Doppler motion, and a nearly constant ice profile in the single-layer stratocumulus suggests that vertical mixing is responsible for its longevity observed during ISDAC. Data acquired in cirrus on flights between Barrow and Fairbanks, Alaska, are improving the understanding of the performance of cloud probes in ice. Furthermore, ISDAC data will improve the representation of cloud and aerosol processes in models covering a variety of spatial and temporal scales, and determine the extent to which surface measurements can provide retrievals of aerosols, clouds, precipitation, and radiative heating.« less

  10. Indirect and semi-direct aerosol campaign: The impact of Arctic aerosols on clouds

    SciTech Connect

    McFarquhar, Greg M.; Ghan, Steven; Verlinde, Johannes; Korolev, Alexei; Strapp, J. Walter; Schmid, Beat; Tomlinson, Jason M.; Wolde, Menqistu; Brooks, Sarah D.; Cziczo, Dan; Dubey, Manvendra K.; Fan, Jiwen; Flynn, Connor; Gultepe, Ismail; Hubbe, John; Gilles, Mary K.; Laskin, Alexander; Lawson, Paul; Leaitch, W. Richard; Liu, Peter; Liu, Xiaohong; Lubin, Dan; Mazzoleni, Claudio; Macdonald, Ann -Marie; Moffet, Ryan C.; Morrison, Hugh; Ovchinnikov, Mikhail; Ronfeld, Debbie; Shupe, Matthew D.; Xie, Shaocheng; Zelenyuk, Alla; Bae, Kenny; Freer, Matt; Glen, Andrew

    2011-02-01

    A comprehensive dataset of microphysical and radiative properties of aerosols and clouds in the boundary layer in the vicinity of Barrow, Alaska, was collected in April 2008 during the Indirect and Semi-Direct Aerosol Campaign (ISDAC). ISDAC's primary aim was to examine the effects of aerosols, including those generated by Asian wildfires, on clouds that contain both liquid and ice. ISDAC utilized the Atmospheric Radiation Measurement Pro- gram's permanent observational facilities at Barrow and specially deployed instruments measuring aerosol, ice fog, precipitation, and radiation. The National Research Council of Canada Convair-580 flew 27 sorties and collected data using an unprecedented 41 stateof- the-art cloud and aerosol instruments for more than 100 h on 12 different days. Aerosol compositions, including fresh and processed sea salt, biomassburning particles, organics, and sulfates mixed with organics, varied between flights. Observations in a dense arctic haze on 19 April and above, within, and below the single-layer stratocumulus on 8 and 26 April are enabling a process-oriented understanding of how aerosols affect arctic clouds. Inhomogeneities in reflectivity, a close coupling of upward and downward Doppler motion, and a nearly constant ice profile in the single-layer stratocumulus suggests that vertical mixing is responsible for its longevity observed during ISDAC. Data acquired in cirrus on flights between Barrow and Fairbanks, Alaska, are improving the understanding of the performance of cloud probes in ice. Furthermore, ISDAC data will improve the representation of cloud and aerosol processes in models covering a variety of spatial and temporal scales, and determine the extent to which surface measurements can provide retrievals of aerosols, clouds, precipitation, and radiative heating.

  11. Dispersion in alluvial convergent estuaries

    NASA Astrophysics Data System (ADS)

    Zhang, Zhilin; Savenije, Hubert H. G.

    2016-04-01

    The Van der Burgh's equation for longitudinal effective dispersion is a purely empirical method with practical implications. Its application to the effective tidal average dispersion under equilibrium conditions appears to have excellent performance in a wide range of alluvial estuaries. In this research, we try to find out the physical meaning of Van der Burgh's coefficient. Researchers like MacCready, Fischer, Kuijper, Hansen and Rattray have tried to split up dispersion into its constituents which did not do much to explain overall behaviour. In addition, traditional literature on dispersion is mostly related to flumes with constant cross-section. This research is about understanding the Van der Burgh's coefficient facing the fact that natural estuaries have exponentially varying cross-section. The objective is to derive a simple 1-D model considering both longitudinal and lateral mixing processes based on field observations (theoretical derivation). To that effect, we connect dispersion with salinity using the salt balance equation. Then we calculate the salinity along the longitudinal direction and compare it to the observed salinity. Calibrated dispersion coefficients in a range of estuaries are then compared with new expressions for the Van der Burgh's coefficient K and it is analysed if K varies from estuary to estuary. The set of reliable data used will be from estuaries: Kurau, Perak, Bernam, Selangor, Muar, Endau, Maputo, Thames, Corantijn, Sinnamary, Mae Klong, Lalang, Limpopo, Tha Chin, Chao Phraya, Edisto and Elbe.

  12. Ruby lidar observations and trajectory analysis of stratospheric aerosols injected by the volcanic eruptions of El Chichon

    NASA Technical Reports Server (NTRS)

    Uchino, O.; Tabata, T.; Akita, I.; Okada, Y.; Naito, K.

    1985-01-01

    Large amounts of aerosol particles and gases were injected into the lower stratosphere by the violet volcanic eruptions of El Chichon on March 28, and April 3 and 4, 1982. Observational results obtained by a ruby lidar at Tsukuba (36.1 deg N, 140.1 deg E) are shown, and some points of latitude dispersion processes of aerosols are discussed.

  13. Does the Madden-Julian Oscillation Influence Aerosol Variability?

    NASA Astrophysics Data System (ADS)

    Tian, B.; Waliser, D. E.; Kahn, R. A.; Li, Q.; Yung, Y. L.; Tyranowski, T.; Geogdzhayev, I. V.; Mishchenko, M. I.; Torres, O.; Smirnov, A.

    2007-12-01

    We investigate the modulation of aerosols by the Madden-Julian Oscillation (MJO) using satellite-based global aerosol products, including aerosol index (AI) from the Total Ozone Mapping Spectrometer (TOMS) on Nimbus-7, and aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Advanced Very High Resolution Radiometer (AVHRR) on NOAA satellites. A composite analysis is performed for boreal winter, and the global pentad rainfall data from the NOAA Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) are used to identify MJO events. The MJO composites exhibit large variations in the TOMS AI and MODIS/AVHRR AOT over the equatorial Indian and western Pacific Oceans where MJO convection is active, as well as the tropical Africa and Atlantic Ocean where MJO convection is relatively weak but the background aerosol level is relatively high. A strong inverse linear relationship between the TOMS AI and rainfall anomalies, but a weaker, less coherent positive correlation between the MODIS/AVHRR AOT and rainfall anomalies, were found. The Aerosol Robotic Network AOT pattern at Kaashidoo (73.5°E, 4.9°N) and Nauru (167°E, 0.5°S) is more consistent with MODIS and AVHRR. These results indicate a connection between the MJO, its associated rainfall and circulation variability, and the observed aerosol variations. Several physical and non-physical factors that may contribute to the observed aerosol-rainfall relationship, such as aerosol humidification effect, wet deposition, surface wind speed, phytoplankton, different sensor sensitivities (absorbing versus non-absorbing aerosols and upper versus lower tropospheric aerosols), sampling issue, and cloud contamination, are discussed. However, a clear causal explanation for the observed patterns remains elusive. Further investigation is needed to unravel this complex aerosol-rainfall relationship.

  14. Characterizing Uncertainty in Global Aerosol Retrievals from Multiple Spaceborne Sensors

    NASA Astrophysics Data System (ADS)

    Petrenko, M.; Smirnov, A.; Ichoku, C. M.

    2014-12-01

    Complementary global aerosol products have been routinely available from multiple spaceborne sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, SeaWiFS, and VIIRS. However, a variety of studies suggest that individual aerosol products have significant differences in the geographic distribution of their retrieval uncertainties. Nonetheless, it can be difficult or impractical to track down relevant product validation studies and invest time in mastering the proprietary file formats of these aerosol products. As a result, many studies are performed using data from one or two most familiar products that, oftentimes, may not be optimal for a given region of interest. In this presentation, we will use Aerosol Robotic Network (AERONET) and Maritime Aerosol Network (MAN) data within the framework of the Multi-sensor Aerosol Products Sampling System (MAPSS) to catalog the accuracy of aerosol retrievals from the spaceborne sensors listed above. We will report our findings in analyzing the spatial and temporal distributions of the uncertainties in the global over-land and maritime retrievals of aerosols based on inter-comparing spaceborne data with coincident ground-based measurements from both AERONET and MAN. We will also explain our vision of how this analysis can be used as a base for a multi-sensor aerosol product package that would help end users to make a more informed choice when selecting data for their regions of interest.

  15. Evaluating the Impact of Aerosols on Numerical Weather Prediction

    NASA Astrophysics Data System (ADS)

    Freitas, Saulo; Silva, Arlindo; Benedetti, Angela; Grell, Georg; Members, Wgne; Zarzur, Mauricio

    2015-04-01

    The Working Group on Numerical Experimentation (WMO, http://www.wmo.int/pages/about/sec/rescrosscut/resdept_wgne.html) has organized an exercise to evaluate the impact of aerosols on NWP. This exercise will involve regional and global models currently used for weather forecast by the operational centers worldwide and aims at addressing the following questions: a) How important are aerosols for predicting the physical system (NWP, seasonal, climate) as distinct from predicting the aerosols themselves? b) How important is atmospheric model quality for air quality forecasting? c) What are the current capabilities of NWP models to simulate aerosol impacts on weather prediction? Toward this goal we have selected 3 strong or persistent events of aerosol pollution worldwide that could be fairly represented in current NWP models and that allowed for an evaluation of the aerosol impact on weather prediction. The selected events includes a strong dust storm that blew off the coast of Libya and over the Mediterranean, an extremely severe episode of air pollution in Beijing and surrounding areas, and an extreme case of biomass burning smoke in Brazil. The experimental design calls for simulations with and without explicitly accounting for aerosol feedbacks in the cloud and radiation parameterizations. In this presentation we will summarize the results of this study focusing on the evaluation of model performance in terms of its ability to faithfully simulate aerosol optical depth, and the assessment of the aerosol impact on the predictions of near surface wind, temperature, humidity, rainfall and the surface energy budget.

  16. Chamber for Aerosol Deposition of Bioparticles

    NASA Technical Reports Server (NTRS)

    Kern, Roger; Kirschner, Larry

    2008-01-01

    Laboratory apparatus is depicted that is a chamber for aerosol deposition of bioparticles on surfaces of test coupons. It is designed for primary use in inoculating both flat and three-dimensional objects with approximately reproducible, uniform dispersions of bacterial spores of the genus Bacillus so that the objects could be used as standards for removal of the spores by quantitative surface sampling and/or cleaning processes. The apparatus is also designed for deposition of particles other than bacterial spores, including fungal spores, viruses, bacteriophages, and standard micron-sized beads. The novelty of the apparatus lies in the combination of a controllable nebulization system with a settling chamber large enough to contain a significant number of test coupons. Several companies market other nebulizer systems, but none are known to include chambers for deposition of bioparticles to mimic the natural fallout of bioparticles. The nebulization system is an expanded and improved version of commercially available aerosol generators that include nebulizers and drying columns. In comparison with a typical commercial aerosol generator, this system includes additional, higher-resolution flowmeters and an additional pressure regulator. Also, unlike a typical commercial aerosol generator, it includes stopcocks for separately controlling flows of gases to the nebulizer and drying column. To maximize the degree of uniformity of dispersion of bioaerosol, the chamber is shaped as an axisymmetrical cylinder and the aerosol generator is positioned centrally within the chamber and aimed upward like a fountain. In order to minimize electric charge associated with the aerosol particles, the drying column is made of aluminum, the drying column is in direct contact with an aluminum base plate, and three equally spaced Po-210 antistatic strips are located at the exit end of the drying column. The sides and top of the chamber are made of an acrylic polymer; to prevent

  17. Dominant Aerosol Particle Type/Mixture Identification at Worldwide Locations Using the Aerosol Robotic Network (AERONET)

    NASA Astrophysics Data System (ADS)

    Giles, D. M.; Holben, B.; Eck, T. F.; Sinyuk, A.; Smirnov, A.; Slutsker, I.; Dickerson, R. R.; Thompson, A. M.; Schafer, J. S.

    2011-12-01

    Aerosol absorption results in atmospheric heating for various forms of particulate matter - we address means of partitioning mineral dust, pollution (e.g., black and brown carbon), and mixtures of the two using remote sensing techniques. Remotely sensed spectral aerosol optical depth (AOD) and single scattering albedo (SSA) derived from Aerosol Robotic Network (AERONET) sun photometer measurements can be used to calculate the absorption aerosol optical depth (AAOD) at 440, 675, and 870 nm. The spectral change in AAOD with wavelength on logarithmic scales provides the absorption Angstrom exponent (AAE). Recently, a few studies have shown that the relationship between aerosol absorption (i.e., AAE or SSA) and aerosol size [i.e., Angstrom exponent (AE) or fine mode fraction (FMF) of the AOD] can estimate the dominant aerosol particle types/mixtures (i.e., dust, pollution, and dust and pollution mixtures) [Bergstrom et al., 2007; Russell et al., 2010; Lee et al. 2010; Giles et al., 2011]. To evaluate these methods, approximately 20 AERONET sites were grouped into various aerosol categories (i.e., dust, mixed, urban/industrial, and biomass burning) based on aerosol types/mixtures identified in previous studies. For data collected between 1999 and 2010, the long-term data set was analyzed to determine the magnitude of spectral AAOD, perform a sensitivity study on AAE by varying the spectral AOD and SSA, and identify dominant aerosol particle types/mixtures. An assessment of the spectral AAOD showed, on average, that the mixed (dust and pollution) category had the highest absorption (AAE ~1.5) followed by biomass burning (AAE~1.3), dust (AAE~1.7), and urban/industrial (AAE~1.2) categories with AAOD (440 nm) varying between 0.03 and 0.09 among these categories. Perturbing input parameters based on the expected uncertainties for AOD (±0.01) and SSA [±0.03; for cases where AOD(440 nm)>0.4], the sensitivity study showed the perturbed AAE mean varied from the unperturbed

  18. Ambient aerosol analysis using aerosol-time-of-flight mass spectrometry

    SciTech Connect

    Prather, K.A.; Noble, C.A.; Liu, D.Y.; Silva, P.J.; Fergenson, D.F.

    1996-10-01

    We have recently developed a technique, Aerosol-Time-of-Flight Mass Spectrometry (ATOFMS), which is capable of real-time determination of the aerodynamic size and chemical composition of individual aerosol particles. In order to obtain such information, the techniques of aerodynamic particle sizing and time-of-flight mass spectrometry are combined in a single instrument. ATOFMS is being used for the direct analysis of ambient aerosols with the goal of establishing correlations between particle size and chemical composition. Currently, measurements are being made to establish potential links between the presence of particular types of particles with such factors as the time of day, weather conditions, and concentration levels of gaseous smog components such as NO{sub x} and ozone. This data will be used to help establish a better understanding of tropospheric gas-aerosol processes. This talk will discuss the operating principles of ATOFMS as well as present the results of ambient analysis studies performed in our laboratory.

  19. Volcanic Aerosol Evolution: Model vs. In Situ Sampling

    NASA Astrophysics Data System (ADS)

    Pfeffer, M. A.; Rietmeijer, F. J.; Brearley, A. J.; Fischer, T. P.

    2002-12-01

    Volcanoes are the most significant non-anthropogenic source of tropospheric aerosols. Aerosol samples were collected at different distances from 92°C fumarolic source at Poás Volcano. Aerosols were captured on TEM grids coated by a thin C-film using a specially designed collector. In the sampling, grids were exposed to the plume for 30-second intervals then sealed and frozen to prevent reaction before ATEM analysis to determine aerosol size and chemistry. Gas composition was established using gas chromatography, wet chemistry techniques, AAS and Ion Chromatography on samples collected directly from a fumarolic vent. SO2 flux was measured remotely by COSPEC. A Gaussian plume dispersion model was used to model concentrations of the gases at different distances down-wind. Calculated mixing ratios of air and the initial gas species were used as input to the thermo-chemical model GASWORKS (Symonds and Reed, Am. Jour. Sci., 1993). Modeled products were compared with measured aerosol compositions. Aerosols predicted to precipitate out of the plume one meter above the fumarole are [CaSO4, Fe2.3SO4, H2SO4, MgF2. Na2SO4, silica, water]. Where the plume leaves the confines of the crater, 380 meters distant, the predicted aerosols are the same, excepting FeF3 replacing Fe2.3SO4. Collected aerosols show considerable compositional differences between the sampling locations and are more complex than those predicted. Aerosols from the fumarole consist of [Fe +/- Si,S,Cl], [S +/- O] and [Si +/- O]. Aerosols collected on the crater rim consist of the same plus [O,Na,Mg,Ca], [O,Si,Cl +/- Fe], [Fe,O,F] and [S,O +/- Mg,Ca]. The comparison between results obtained by the equilibrium gas model and the actual aerosol compositions shows that an assumption of chemical and thermal equilibrium evolution is invalid. The complex aerosols collected contrast the simple formulae predicted. These findings show that complex, non-equilibrium chemical reactions take place immediately upon volcanic

  20. An investigation of Raman lidar aerosol measurements and their application to the study of the aerosol indirect effect

    NASA Astrophysics Data System (ADS)

    Russo, Felicita

    The problem of the increasing global atmospheric temperature has motivated a large interest in studying the mechanisms that can influence the radiative balance of the planet. Aerosols are responsible for several radiative effects in the atmosphere: an increase of aerosol loading in the atmosphere increases the reflectivity of the atmosphere and has an estimated cooling effect and is called the aerosol direct effect. Another process involving aerosols is the effect that an increase in their concentration in the atmosphere has on the formation of clouds and is called the aerosol indirect effect. In the latest IPCC report, the aerosol indirect effect was estimated to be responsible for a radiative forcing ranging between -0.3 W/m2 to -1.8 W/m2, which can be as large as, but opposite in sign to, the radiative forcing due to greenhouse gases. The main goal of this dissertation is to study the Raman lidar measurements of quantities relevant for the investigation of the aerosol indirect effect and ultimately to apply these measurements to a quantification of the aerosol indirect effect. In particular we explore measurements of the aerosol extinction from both the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) and the US Department of Energy (DOE) ARM Climate Research Facility Raman Lidar (CARL). An algorithm based on the chi-squared technique to calculate the aerosol extinction, which was introduced first by Whiteman (1999), is here validated using both simulated and experimental data. It has been found as part of this validation that the aerosol extinction uncertainty retrieved with this technique is on average smaller that the uncertainty calculated with the technique traditionally used. This algorithm was then used to assess the performance of the CARL aerosol extinction retrieval for low altitudes. Additionally, since CARL has been upgraded with a channel for measuring Raman liquid water scattering, measurements of cloud liquid water content, droplet

  1. Production of Highly Charged Pharmaceutical Aerosols Using a New Aerosol Induction Charger

    PubMed Central

    Golshahi, Laleh; Longest, P. Worth; Holbrook, Landon; Snead, Jessica; Hindle, Michael

    2015-01-01

    Purpose Properly charged particles can be used for effective lung targeting of pharmaceutical aerosols. The objective of this study was to characterize the performance of a new induction charger that operates with a mesh nebulizer for the production of highly charged submicrometer aerosols to bypass the mouth-throat and deliver clinically relevant doses of medications to the lungs. Methods Variables of interest included combinations of model drug (i.e. albuterol sulfate) and charging excipient (NaCl) as well as strength of the charging field (1–5 kV/cm). Aerosol charge and size were measured using a modified electrical low pressure impactor system combined with high performance liquid chromatography. Results At the approximate mass median aerodynamic diameter (MMAD) of the aerosol (~ 0.4 μm), the induction charge on the particles was an order of magnitude above the field and diffusion charge limit. The nebulization rate was 439.3 ± 42.9 μl/min, which with a 0.1 % w/v solution delivered 419.5 ± 34.2 μg of medication per minute. A new correlation was developed to predict particle charge produced by the induction charger. Conclusions The combination of the aerosol induction charger and predictive correlations will allow for the practical generation and control of charged submicrometer aerosols for targeting deposition within the lungs. PMID:25823649

  2. The Aerosol Modeling Testbed: A community tool to objectively evaluate aerosol process modules

    SciTech Connect

    Fast, Jerome D.; Gustafson, William I.; Chapman, Elaine G.; Easter, Richard C.; Rishel, Jeremy P.; Zaveri, Rahul A.; Grell, Georg; Barth, Mary

    2011-03-02

    This study describes a new modeling paradigm that significantly advances how the third activity is conducted while also fully exploiting data and findings from the first two activities. The Aerosol Modeling Testbed (AMT) is a computational framework for the atmospheric sciences community that streamlines the process of testing and evaluating aerosol process modules over a wide range of spatial and temporal scales. The AMT consists of a fully-coupled meteorology-chemistry-aerosol model, and a suite of tools to evaluate the performance of aerosol process modules via comparison with a wide range of field measurements. The philosophy of the AMT is to systematically and objectively evaluate aerosol process modules over local to regional spatial scales that are compatible with most field campaigns measurement strategies. The performance of new treatments can then be quantified and compared to existing treatments before they are incorporated into regional and global climate models. Since the AMT is a community tool, it also provides a means of enhancing collaboration and coordination among aerosol modelers.

  3. Volcanic Aerosol Radiative Properties

    NASA Technical Reports Server (NTRS)

    Lacis, Andrew

    2015-01-01

    Large sporadic volcanic eruptions inject large amounts of sulfur bearing gases into the stratosphere which then get photochemically converted to sulfuric acid aerosol droplets that exert a radiative cooling effect on the global climate system lasting for several years.

  4. Palaeoclimate: Aerosols and rainfall

    NASA Astrophysics Data System (ADS)

    Partin, Jud

    2015-03-01

    Instrumental records have hinted that aerosol emissions may be shifting rainfall over Central America southwards. A 450-year-long precipitation reconstruction indicates that this shift began shortly after the Industrial Revolution.

  5. Aerosol lenses propagation model.

    PubMed

    Tremblay, Grégoire; Roy, Gilles

    2011-09-01

    We propose a model based on the properties of cascading lenses modulation transfer function (MTF) to reproduce the irradiance of a screen illuminated through a dense aerosol cloud. In this model, the aerosol cloud is broken into multiple thin layers considered as individual lenses. The screen irradiance generated by these individual layers is equivalent to the point-spread function (PSF) of each aerosol lens. Taking the Fourier transform of the PSF as a MTF, we cascade the lenses MTF to find the cloud MTF. The screen irradiance is found with the Fourier transform of this MTF. We show the derivation of the model and we compare the results with the Undique Monte Carlo simulator for four aerosols at three optical depths. The model is in agreement with the Monte Carlo for all the cases tested. PMID:21886230

  6. Long-term Observation of Aerosol Optical Properties at the SORPES station in Nanjing, China

    NASA Astrophysics Data System (ADS)

    Shen, Yicheng; Ding, Aijun; Virkkula, Aki; Wang, Jiaping; Chi, Xuguang; Qi, Ximeng; Liu, Qiang; Zheng, Longfei; Xie, Yuning

    2016-04-01

    Atmospheric aerosols influence the earth's radiation budget by scattering and absorbing solar radiation and contribute substantial uncertainty in the estimation of climate forcing. Thorough and comprehensive measurements on different parameters including absorption and scattering coefficient, wavelength dependence and angular dependence along with their daily and seasonal variation help to understand the influence of aerosol on radiation. 2-years continuous measurement of aerosol optical properties has been conducted from June 2013 to May 2015 at the Station for Observing Regional Process of Earth System (SORPES) station, which is a regional background station located in downwind direction of Yangtze River Delta (YRD) urban agglomeration in China. A 7-wavelenths aethalometer and a 3-wavelenths nephelometer were used to measure absorption and scattering coefficient, and also other parameters like single scattering albedo (SSA), absorption angstrom Exponent (AAE), scattering angstrom exponent (SAE) and back-scattering refraction. In addtion, simultaneous measurements on chemical composition and particle size distribution were performed so as to investigate the dependencies of aerosol optical properties on chemical composition and size distribution. To get further insight on the influencing factors, Lagrangian particle dispersion modeling (LPDM) was employed for source identification in this study. The averages of absorption coefficient, scattering coefficient and SSA are 26.0±18.7 Mm-1, 426±327 Mm-1 , 0.936±0.3 at 520nm respectively for whole period. SAE between 450 and 635nm is 1.299±0.34 and have strong negative correlation with particle Surface Mean Diameter (SMD). AAE between 370 and 950nm is 1.043±0.15 for whole period but growth to more than 1.6 in all identified Biomass Burning (BB) events.

  7. The effect of organic aerosol material on aerosol reactivity towards ozone

    NASA Astrophysics Data System (ADS)

    Batenburg, Anneke; Gaston, Cassandra; Thornton, Joel; Virtanen, Annele

    2015-04-01

    After aerosol particles are formed or emitted into the atmosphere, heterogeneous reactions with gaseous oxidants cause them to 'age'. Aging can change aerosol properties, such as the hygroscopicity, which is an important parameter in how the particles scatter radiation and form clouds. Conversely, heterogeneous reactions on aerosol particles play a significant role in the cycles of various atmospheric trace gases. Organic compounds, a large part of the total global aerosol matter, can exist in liquid or amorphous (semi)solid physical phases. Different groups have shown that reactions with ozone (O3) can be limited by bulk diffusion in organic aerosol, particularly in viscous, (semi)solid materials, and that organic coatings alter the surface interactions between gas and aerosol particles. We aim to better understand and quantify how the viscosity and phase of organic aerosol matter affect gas-particle interactions. We have chosen the reaction of O3 with particles composed of a potassium iodide (KI) core and a variable organic coating as a model system. The reaction is studied in an aerosol flow reactor that consists of a laminar flow tube and a movable, axial injector for the injection of O3. The aerosol-containing air is inserted at the tube's top. The interaction length (and therefore time), between the particles and the O3 can be varied by moving the injector. Alternat