Electrospray ionizer for mass spectrometry of aerosol particles

DOEpatents

He, Siqin; Hogan, Chris; Li, Lin; Liu, Benjamin Y. H.; Naqwi, Amir; Romay, Francisco

2017-09-19

A device and method are disclosed to apply ESI-based mass spectroscopy to submicrometer and nanometer scale aerosol particles. Unipolar ionization is utilized to charge the particles in order to collect them electrostatically on the tip of a tungsten rod. Subsequently, the species composing the collected particles are dissolved by making a liquid flow over the tungsten rod. This liquid with dissolved aerosol contents is formed into highly charged droplets, which release unfragmented ions for mass spectroscopy, such as time-of-flight mass spectroscopy. The device is configured to operate in a switching mode, wherein aerosol deposition occurs while solvent delivery is turned off and vice versa.

Relating Aerosol Mass and Optical Depth in the Summertime Continental Boundary Layer

NASA Astrophysics Data System (ADS)

Brock, C. A.; Wagner, N.; Middlebrook, A. M.; Attwood, A. R.; Washenfelder, R. A.; Brown, S. S.; McComiskey, A. C.; Gordon, T. D.; Welti, A.; Carlton, A. G.; Murphy, D. M.

2014-12-01

Aerosol optical depth (AOD), the column-integrated ambient aerosol light extinction, is determined from satellite and ground-based remote sensing measurements. AOD is the parameter most often used to validate earth system model simulations of aerosol mass. Relating aerosol mass to AOD, however, is problematic due to issues including aerosol water uptake as a function of relative humidity (RH) and the complicated relationship between aerosol physicochemical properties and light extinction. Measurements of aerosol microphysical, chemical, and optical properties help to constrain the relationship between aerosol mass and optical depth because aerosol extinction at ambient RH is a function of the abundance, composition and size distribution of the aerosol. We use vertical profiles of humidity and dry aerosol extinction observed in the southeastern United States (U.S.) to examine the relationship between submicron aerosol mass concentration and extinction at ambient RH. We show that the κ-Köhler parameterization directly, and without additional Mie calculations, describes the change in extinction with varying RH as a function of composition for both aged aerosols typical of the polluted summertime continental boundary layer and the biomass burning aerosols we encountered. We calculate how AOD and the direct radiative effect in the eastern U.S. have likely changed due to trends in aerosol composition in recent decades. We also examine the sensitivity of AOD to the RH profile and to aerosol composition, size distribution and abundance.

Trends in sulfate and organic aerosol mass in the Southeast U.S.: Impact on aerosol optical depth and radiative forcing

NASA Astrophysics Data System (ADS)

Attwood, A. R.; Washenfelder, R. A.; Brock, C. A.; Hu, W.; Baumann, K.; Campuzano-Jost, P.; Day, D. A.; Edgerton, E. S.; Murphy, D. M.; Palm, B. B.; McComiskey, A.; Wagner, N. L.; Sá, S. S.; Ortega, A.; Martin, S. T.; Jimenez, J. L.; Brown, S. S.

2014-11-01

Emissions of SO2 in the United States have declined since the early 1990s, resulting in a decrease in aerosol sulfate mass in the Southeastern U.S. of -4.5(±0.9)% yr-1 between 1992 and 2013. Organic aerosol mass, the other major aerosol component in the Southeastern U.S., has decreased more slowly despite concurrent emission reductions in anthropogenic precursors. Summertime measurements in rural Alabama quantify the change in aerosol light extinction as a function of aerosol composition and relative humidity. Application of this relationship to composition data from 2001 to 2013 shows that a -1.1(±0.7)% yr-1 decrease in extinction can be attributed to decreasing aerosol water mass caused by the change in aerosol sulfate/organic ratio. Calculated reductions in extinction agree with regional trends in ground-based and satellite-derived aerosol optical depth. The diurnally averaged summertime surface radiative effect has changed by 8.0 W m-2, with 19% attributed to the decrease in aerosol water.

Characterization of urban aerosol using aerosol mass spectrometry and proton nuclear magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Cleveland, M. J.; Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Lefer, B.; Rappenglück, B.

2012-07-01

Particulate matter was measured during August and September of 2006 in Houston as part of the Texas Air Quality Study II Radical and Aerosol Measurement Project. Aerosol size and composition were determined using an Aerodyne quadrupole aerosol mass spectrometer. Aerosol was dominated by sulfate (4.1 ± 2.6 μg m-3) and organic material (5.5 ± 4.0 μg m-3), with contributions of organic material from both primary (˜32%) and secondary (˜68%) sources. Secondary organic aerosol appears to be formed locally. In addition, 29 aerosol filter samples were analyzed using proton nuclear magnetic resonance (1H NMR) spectroscopy to determine relative concentrations of organic functional groups. Houston aerosols are less oxidized than those observed elsewhere, with smaller relative contributions of carbon-oxygen double bonds. These particles do not fit 1H NMR source apportionment fingerprints for identification of secondary, marine, and biomass burning organic aerosol, suggesting that a new fingerprint for highly urbanized and industrially influenced locations be established.

Enhancing non-refractory aerosol apportionment from an urban industrial site through receptor modeling of complete high time-resolution aerosol mass spectra

NASA Astrophysics Data System (ADS)

McGuire, M. L.; Chang, R. Y.-W.; Slowik, J. G.; Jeong, C.-H.; Healy, R. M.; Lu, G.; Mihele, C.; Abbatt, J. P. D.; Brook, J. R.; Evans, G. J.

2014-08-01

Receptor modeling was performed on quadrupole unit mass resolution aerosol mass spectrometer (Q-AMS) sub-micron particulate matter (PM) chemical speciation measurements from Windsor, Ontario, an industrial city situated across the Detroit River from Detroit, Michigan. Aerosol and trace gas measurements were collected on board Environment Canada's Canadian Regional and Urban Investigation System for Environmental Research (CRUISER) mobile laboratory. Positive matrix factorization (PMF) was performed on the AMS full particle-phase mass spectrum (PMFFull MS) encompassing both organic and inorganic components. This approach compared to the more common method of analyzing only the organic mass spectra (PMFOrg MS). PMF of the full mass spectrum revealed that variability in the non-refractory sub-micron aerosol concentration and composition was best explained by six factors: an amine-containing factor (Amine); an ammonium sulfate- and oxygenated organic aerosol-containing factor (Sulfate-OA); an ammonium nitrate- and oxygenated organic aerosol-containing factor (Nitrate-OA); an ammonium chloride-containing factor (Chloride); a hydrocarbon-like organic aerosol (HOA) factor; and a moderately oxygenated organic aerosol factor (OOA). PMF of the organic mass spectrum revealed three factors of similar composition to some of those revealed through PMFFull MS: Amine, HOA and OOA. Including both the inorganic and organic mass proved to be a beneficial approach to analyzing the unit mass resolution AMS data for several reasons. First, it provided a method for potentially calculating more accurate sub-micron PM mass concentrations, particularly when unusual factors are present, in this case the Amine factor. As this method does not rely on a priori knowledge of chemical species, it circumvents the need for any adjustments to the traditional AMS species fragmentation patterns to account for atypical species, and can thus lead to more complete factor profiles. It is expected that this

Enhancing non-refractory aerosol apportionment from an urban industrial site through receptor modelling of complete high time-resolution aerosol mass spectra

NASA Astrophysics Data System (ADS)

McGuire, M. L.; Chang, R. Y.-W.; Slowik, J. G.; Jeong, C.-H.; Healy, R. M.; Lu, G.; Mihele, C.; Abbatt, J. P. D.; Brook, J. R.; Evans, G. J.

2014-02-01

Receptor modelling was performed on quadrupole unit mass resolution aerosol mass spectrometer (Q-AMS) sub-micron particulate matter (PM) chemical speciation measurements from Windsor, Ontario, an industrial city situated across the Detroit River from Detroit, Michigan. Aerosol and trace gas measurements were collected on board Environment Canada's CRUISER mobile laboratory. Positive matrix factorization (PMF) was performed on the AMS full particle-phase mass spectrum (PMFFull MS) encompassing both organic and inorganic components. This approach was compared to the more common method of analysing only the organic mass spectra (PMFOrg MS). PMF of the full mass spectrum revealed that variability in the non-refractory sub-micron aerosol concentration and composition was best explained by six factors: an amine-containing factor (Amine); an ammonium sulphate and oxygenated organic aerosol containing factor (Sulphate-OA); an ammonium nitrate and oxygenated organic aerosol containing factor (Nitrate-OA); an ammonium chloride containing factor (Chloride); a hydrocarbon-like organic aerosol (HOA) factor; and a moderately oxygenated organic aerosol factor (OOA). PMF of the organic mass spectrum revealed three factors of similar composition to some of those revealed through PMFFull MS: Amine, HOA and OOA. Including both the inorganic and organic mass proved to be a beneficial approach to analysing the unit mass resolution AMS data for several reasons. First, it provided a method for potentially calculating more accurate sub-micron PM mass concentrations, particularly when unusual factors are present, in this case, an Amine factor. As this method does not rely on a priori knowledge of chemical species, it circumvents the need for any adjustments to the traditional AMS species fragmentation patterns to account for atypical species, and can thus lead to more complete factor profiles. It is expected that this method would be even more useful for HR-ToF-AMS data, due to the ability

Pollutants identification of ambient aerosols by two types of aerosol mass spectrometers over southeast coastal area, China.

PubMed

Yan, Jinpei; Chen, Liqi; Lin, Qi; Zhao, Shuhui; Li, Lei

2018-02-01

Two different aerosol mass spectrometers, Aerodyne Aerosol Mass Spectrometer (AMS) and Single Particle Aerosol Mass Spectrometer (SPAMS) were deployed to identify the aerosol pollutants over Xiamen, representing the coastal urban area. Five obvious processes were classified during the whole observation period. Organics and sulfate were the dominant components in ambient aerosols over Xiamen. Most of the particles were in the size range of 0.2-1.0μm, accounting for over 97% of the total particles measured by both instruments. Organics, as well as sulfate, measured by AMS were in good correlation with measured by SPAMS. However, high concentration of NH 4 + was obtained by AMS, while extremely low value of NH 4 + was detected by SPAMS. Contrarily, high particle number counts of NO 3 - and Cl - were given by SPAMS while low concentrations of NO 3 - and Cl - were measured by AMS. The variations of POA and SOA obtained from SPAMS during event 1 and event 2 were in accordance with the analysis of HOA and OOA given by AMS, suggesting that both of AMS and SPAMS can well identify the organic clusters of aerosol particles. Overestimate or underestimate of the aerosol sources and acidity would be present in some circumstances when the measurement results were used to analyze the aerosol properties, because of the detection loss of some species for both instruments. Copyright © 2017. Published by Elsevier B.V.

Aerosol detection efficiency in inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Hubbard, Joshua A.; Zigmond, Joseph A.

2016-05-01

An electrostatic size classification technique was used to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Size-segregated particles were counted with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized by the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10- 5 to 10- 11. Free molecular heat and mass transfer theory was applied, but

Aerosol detection efficiency in inductively coupled plasma mass spectrometry

DOE PAGES

Hubbard, Joshua A.; Zigmond, Joseph A.

2016-03-02

We used an electrostatic size classification technique to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Moreover, we counted size-segregated particles with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized bymore » the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10 -5 to 10 -11. Free molecular heat and mass transfer theory was

Formation of secondary organic aerosols from gas-phase emissions of heated cooking oils

NASA Astrophysics Data System (ADS)

Liu, Tengyu; Li, Zijun; Chan, ManNin; Chan, Chak K.

2017-06-01

Cooking emissions can potentially contribute to secondary organic aerosol (SOA) but remain poorly understood. In this study, formation of SOA from gas-phase emissions of five heated vegetable oils (i.e., corn, canola, sunflower, peanut and olive oils) was investigated in a potential aerosol mass (PAM) chamber. Experiments were conducted at 19-20 °C and 65-70 % relative humidity (RH). The characterization instruments included a scanning mobility particle sizer (SMPS) and a high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS). The efficiency of SOA production, in ascending order, was peanut oil, olive oil, canola oil, corn oil and sunflower oil. The major SOA precursors from heated cooking oils were related to the content of monounsaturated fat and omega-6 fatty acids in cooking oils. The average production rate of SOA, after aging at an OH exposure of 1. 7 × 1011 molecules cm-3 s, was 1. 35 ± 0. 30 µg min-1, 3 orders of magnitude lower compared with emission rates of fine particulate matter (PM2. 5) from heated cooking oils in previous studies. The mass spectra of cooking SOA highly resemble field-derived COA (cooking-related organic aerosol) in ambient air, with R2 ranging from 0.74 to 0.88. The average carbon oxidation state (OSc) of SOA was -1.51 to -0.81, falling in the range between ambient hydrocarbon-like organic aerosol (HOA) and semi-volatile oxygenated organic aerosol (SV-OOA), indicating that SOA in these experiments was lightly oxidized.

Performance Comparison of Field Portable Instruments to the Scanning Mobility Particle Sizer Using Monodispersed and Polydispersed Sodium Chloride Aerosols.

PubMed

Vo, Evanly; Horvatin, Matthew; Zhuang, Ziqing

2018-05-21

This study compared the performance of the following field portable aerosol instrument sets to performance of the reference Scanning Mobility Particle Sizer (SMPS): the handheld CPC-3007, the portable aerosol mobility spectrometer (PAMS), the NanoScan scanning mobility particle sizer (NanoScan SMPS) combined with an optical particle sizer (OPS). Tests were conducted with monodispersed and polydispersed aerosols. Monodispersed aerosols were controlled at the approximate concentration of 1 × 105 particles cm-3 and four monodispersed particle sizes of 30, 60, 100, and 300 nm were selected and classified for the monodispersed aerosol test, while three different steady-state concentration levels (low, medium, and high: ~8 × 103, 5 × 104, and 1 × 105 particles cm-3, respectively) were selected for the polydispersed aerosol test. For all four monodispersed aerosol sizes, particle concentrations measured with the NanoScan SMPS were within 13% of those measured with the reference SMPS. Particle concentrations measured with the PAMS were within 25% of those measured with the reference SMPS. Concentrations measured with the handheld condensation particle counter were within 30% of those measured with the reference SMPS. For the polydispersed aerosols, the particle sizes and concentrations measured with the NanoScan-OPS compared most favorably with those measured with the reference SMPS for three different concentration levels of low, medium, and high (concentration deviations ≤10% for all three concentration levels; deviations of particle size ≤4%). Although the particle-size comparability between the PAMS and the reference SMPS was quite reasonable with the deviations within 10%, the polydispersed particle concentrations measured with the PAMS were within 36% of those measured with the reference SMPS. The results of this evaluation will be useful for selecting a suitable portable device for our next workplace study phase of respiratory protection assessment. This

Changes in organic aerosol composition with aging inferred from aerosol mass spectra

NASA Astrophysics Data System (ADS)

Ng, N. L.; Canagaratna, M. R.; Jimenez, J. L.; Chhabra, P. S.; Seinfeld, J. H.; Worsnop, D. R.

2011-07-01

Organic aerosols (OA) can be separated with factor analysis of aerosol mass spectrometer (AMS) data into hydrocarbon-like OA (HOA) and oxygenated OA (OOA). We develop a new method to parameterize H:C of OOA in terms of f43 (ratio of m/z 43, mostly C2H3O+, to total signal in the component mass spectrum). Such parameterization allows for the transformation of large database of ambient OOA components from the f44 (mostly CO2+, likely from acid groups) vs. f43 space ("triangle plot") (Ng et al., 2010) into the Van Krevelen diagram (H:C vs. O:C) (Van Krevelen, 1950). Heald et al. (2010) examined the evolution of total OA in the Van Krevelen diagram. In this work total OA is deconvolved into components that correspond to primary (HOA and others) and secondary (OOA) organic aerosols. By deconvolving total OA into different components, we remove physical mixing effects between secondary and primary aerosols which allows for examination of the evolution of OOA components alone in the Van Krevelen space. This provides a unique means of following ambient secondary OA evolution that is analogous to and can be compared with trends observed in chamber studies of secondary organic aerosol formation. The triangle plot in Ng et al. (2010) indicates that f44 of OOA components increases with photochemical age, suggesting the importance of acid formation in OOA evolution. Once they are transformed with the new parameterization, the triangle plot of the OOA components from all sites occupy an area in Van Krevelen space which follows a ΔH:C/ΔO:C slope of ~ -0.5. This slope suggests that ambient OOA aging results in net changes in chemical composition that are equivalent to the addition of both acid and alcohol/peroxide functional groups without fragmentation (i.e. C-C bond breakage), and/or the addition of acid groups with fragmentation. These results provide a framework for linking the bulk aerosol chemical composition evolution to molecular-level studies.

Characterization of ambient aerosols at the San Francisco International Airport using BioAerosol Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steele, P T; McJimpsey, E L; Coffee, K R

2006-03-16

The BioAerosol Mass Spectrometry (BAMS) system is a rapidly fieldable, fully autonomous instrument that can perform correlated measurements of multiple orthogonal properties of individual aerosol particles. The BAMS front end uses optical techniques to nondestructively measure a particle's aerodynamic diameter and fluorescence properties. Fluorescence can be excited at 266nm or 355nm and is detected in two broad wavelength bands. Individual particles with appropriate size and fluorescence properties can then be analyzed more thoroughly in a dual-polarity time-of-flight mass spectrometer. Over the course of two deployments to the San Francisco International Airport, more than 6.5 million individual aerosol particles were fullymore » analyzed by the system. Analysis of the resulting data has provided a number of important insights relevant to rapid bioaerosol detection, which are described here.« less

Aerosol Vacuum-Assisted Plasma Ionization (Aero-VaPI) Coupled to Ion Mobility-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Blair, Sandra L.; Ng, Nga L.; Zambrzycki, Stephen C.; Li, Anyin; Fernández, Facundo M.

2018-02-01

In this communication, we report on the real-time analysis of organic aerosol particles by Vacuum-assisted Plasma Ionization-Mass Spectrometry (Aero-VaPI-MS) using a home-built VaPI ion source coupled to a Synapt G2-S HDMS ion mobility-mass spectrometry (IM-MS) system. Standards of organic molecules of interest in prebiotic chemistry were used to generate aerosols. Monocaprin and decanoic acid aerosol particles were successfully detected in both the positive and negative ion modes, respectively. A complex aerosol mixture of different sizes of polymers of L-malic acid was also examined through ion mobility (IM) separations, resulting in the detection of polymers of up to eight monomeric units. This noncommercial plasma ion source is proposed as a low cost alternative to other plasma ionization platforms used for aerosol analysis, and a higher-performance alternative to more traditional aerosol mass spectrometers. VaPI provides robust online ionization of organics in aerosols without extensive ion activation, with the coupling to IM-MS providing higher peak capacity and excellent mass accuracy. [Figure not available: see fulltext.

Direct gravimetric determination of aerosol mass concentration in central antarctica.

PubMed

Annibaldi, Anna; Truzzi, Cristina; Illuminati, Silvia; Scarponi, Giuseppe

2011-01-01

In Antarctica, experimental difficulties due to extreme conditions have meant that aerosol mass has rarely been measured directly by gravimetry, and only in coastal areas where concentrations were in the range of 1-7 μg m(-3). The present work reports on a careful differential weighing methodology carried out for the first time on the plateau of central Antarctica (Dome C, East Antarctica). To solve problems of accurate aerosol mass measurements, a climatic room was used for conditioning and weighing filters. Measurements were carried out in long stages of several hours of readings with automatic recording of temperature/humidity and mass. This experimental scheme allowed us to sample from all the measurements (up to 2000) carried out before and after exposure, those which were recorded under the most stable humidity conditions and, even more importantly, as close to each other as possible. The automatic reading of the mass allowed us in any case to obtain hundreds of measurements from which to calculate average values with uncertainties sufficiently low to meet the requirements of the differential weighing procedure (±0.2 mg in filter weighing, between ±7% and ±16% both in aerosol mass and concentration measurements). The results show that the average summer aerosol mass concentration (aerodynamic size ≤10 μm) in central Antarctica is about 0.1 μg m(-3), i.e., about 1/10 of that of coastal Antarctic areas. The concentration increases by about 4-5 times at a site very close to the station.

Primary and secondary organic aerosols in Fresno, California during wintertime: Results from high resolution aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Ge, Xinlei; Setyan, Ari; Sun, Yele; Zhang, Qi

2012-10-01

Organic aerosols (OA) were studied in Fresno, California, in winter 2010 with an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). OA dominated the submicron aerosol mass (average = 67%) with an average concentration of 7.9μg m-3 and a nominal formula of C1H1.59N0.014O0.27S0.00008, which corresponds to an average organic mass-to-carbon ratio of 1.50. Three primary OA (POA) factors and one oxygenated OA factor (OOA) representative of secondary OA (SOA) were identified via Positive Matrix Factorization of the high-resolution mass spectra. The three POA factors, which include a traffic-related hydrocarbon-like OA (HOA), a cooking OA (COA), and a biomass burning OA (BBOA) released from residential heating, accounted for an average 57% of the OA mass and up to 80% between 6 - 9 P.M., during which enhanced emissions from evening rush hour traffic, dinner cooking, and residential wood burning were exacerbated by low mixed layer height. The mass-based size distributions of the OA factors were estimated based on multilinear analysis of the size-resolved mass spectra of organics. Both HOA and BBOA peaked at ˜140 nm in vacuum aerodynamic diameter (Dva) while OOA peaked at an accumulation mode of ˜460 nm. COA exhibited a unique size distribution with two size modes centering at ˜200 nm and 450 nm respectively. This study highlights the leading roles played by anthropogenic POA emissions, primarily from traffic, cooking and residential heating, in aerosol pollution in Fresno in wintertime.

A Water Mass Tracer Detected in Aerosols Demonstrates Ocean-Atmosphere Mass Transfer and Links Sea Spray Aerosol to Source Waters

NASA Astrophysics Data System (ADS)

Pendergraft, M.; Grimes, D. J.; Giddings, S. N.; Feddersen, F.; Prather, K. A.; Santander, M.; Lee, C.; Beall, C.

2016-12-01

During September and October of 2015 the Cross Surfzone/Inner-shelf Dye Exchange (CSIDE) project released rhodamine WT dye to study nearshore water movement and exchange offshore along a Southern California sandy beach. We utilized this opportunity to investigate ocean-atmosphere mass transfer via sea spray aerosol and linkage to source waters. Aerosol-concentrating sampling equipment was deployed at beachside and inland locations during three dye releases. Concentrated aerosol samples were analyzed for dye content using fluorescence spectroscopy. Here we present the ocean and atmosphere conditions associated with the presence and absence of dye in aerosol samples. Dye was identified in aerosol samples collected 0.1-0.3 km from the shoreline for 6 hs during the first and third dye releases of the CSIDE project. During these releases the dye persisted in the waters upwind of the sampling equipment. Dye was not detected in aerosol samples collected during the second release during which dye was moved away from waters upwind of the sampling equipment. Recovery of a chemical tracer in sea spray aerosol allows direct linkage to a known source area in the ocean that is independent of, but supported by, wind data. Our observations demonstrate: a tight ocean-atmosphere spatial coupling; a short residence time of coastal marine constituents before transfer to the atmosphere; that the ocean is both a sink for and a source of atmospheric and terrestrial material; and that human inputs to the ocean can return to us in sea spray aerosol.

A thermal desorption mass spectrometer for freshly nucleated secondary aerosol particles

NASA Astrophysics Data System (ADS)

Held, A.; Gonser, S. G.

2012-04-01

Secondary aerosol formation in the atmosphere is observed in a large variety of locations worldwide, introducing new particles to the atmosphere which can grow to sizes relevant for health and climate effects of aerosols. The chemical reactions leading to atmospheric secondary aerosol formation are not yet fully understood. At the same time, analyzing the chemical composition of freshly nucleated particles is still a challenging task. We are currently finishing the development of a field portable aerosol mass spectrometer for nucleation particles with diameters smaller than 30 nm. This instrument consists of a custom-built aerosol sizing and collection unit coupled to a time-of-flight mass spectrometer (TOF-MS). The aerosol sizing and collection unit is composed of three major parts: (1) a unipolar corona aerosol charger, (2) a radial differential mobility analyzer (rDMA) for aerosol size separation, and (3) an electrostatic precipitator for aerosol collection. After collection, the aerosol sample is thermally desorbed, and the resulting gas sample is transferred to the TOF-MS for chemical analysis. The unipolar charger is based on corona discharge from carbon fibres (e.g. Han et al., 2008). This design allows efficient charging at voltages below 2 kV, thus eliminating the potential for ozone production which would interfere with the collected aerosol. With the current configuration the extrinsic charging efficiency for 20 nm particles is 32 %. The compact radial DMA similar to the design of Zhang et al. (1995) is optimized for a diameter range from 1 nm to 100 nm. Preliminary tests show that monodisperse aerosol samples (geometric standard deviation of 1.09) at 10 nm, 20 nm, and 30 nm can easily be separated from the ambient polydisperse aerosol population. Finally, the size-segregated aerosol sample is collected on a high-voltage biased metal filament. The collected sample is protected from contamination using a He sheath counterflow. Resistive heating of the

Mass spectrometry of atmospheric aerosols--recent developments and applications. Part II: On-line mass spectrometry techniques.

PubMed

Pratt, Kerri A; Prather, Kimberly A

2012-01-01

Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of mass spectrometry. Mass spectrometry provides high sensitivity with fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of mass spectrometry of atmospheric aerosols. In Part II of this two-part review, we concentrate on real-time mass spectrometry techniques, which provide high time resolution for insight into brief events and diurnal changes while eliminating the potential artifacts acquired during long-term filter sampling. In particular, real-time mass spectrometry has been shown recently to provide the ability to probe the chemical composition of ambient individual particles <30 nm in diameter to further our understanding of how particles are formed through nucleation in the atmosphere. Further, transportable real-time mass spectrometry techniques are now used frequently on ground-, ship-, and aircraft-based studies around the globe to further our understanding of the spatial distribution of atmospheric aerosols. In addition, coupling aerosol mass spectrometry techniques with other measurements in series has allowed the in situ determination of chemically resolved particle effective density, refractive index, volatility, and cloud activation properties. Copyright © 2011 Wiley Periodicals, Inc.

Aerosol concentration measurements and correlations with air mass trajectories at the Pierre Auger Observatory

NASA Astrophysics Data System (ADS)

Micheletti, M. I.; Louedec, K.; Freire, M.; Vitale, P.; Piacentini, R. D.

2017-06-01

Aerosols play an important role in radiative transfer processes involved in different fields of study. In particular, their influence is crucial in the attenuation of light at astronomical and astrophysical observatories, and has to be taken into account in light transfer models employed to reconstruct the signals. The Andean Argentinean region is increasingly being considered as a good candidate to host such facilities, as well as the ones for solar-energy resources, and an adequate knowledge of aerosols characteristics there is needed, but it is not always possible due to the vast area involved and the scarce atmospheric data at ground. The aim of this work is to find correlations between aerosol data and particle trajectories that can give an insight into the origin and behaviour of aerosols in this zone and can be employed in situations in which one does not have local aerosol measurements. For this purpose, an aerosol spectrometer and dust monitor (Grimm 1.109) was installed at the Pierre Auger Observatory of ultra-high-energy cosmic rays, to record aerosol concentrations in different size intervals, at surface level. These measurements are analysed and correlated with air mass trajectories obtained from HYSPLIT (NOAA) model calculations. High aerosol concentrations are registered predominantly when air masses have travelled mostly over continental areas, mainly from the NE direction, while low aerosol concentrations are found in correspondence with air masses coming from the Pacific Ocean, from the NW direction. Different size distribution patterns were found for the aerosols depending on their origin: marine or continental. This work shows for the first time the size distribution of aerosols registered at the Pierre Auger Observatory. The correlations found between mass and particle concentrations (total and for different size ranges) and HYSPLIT air mass trajectories, confirm that the latter can be employed as a useful tool to infer the sources, evolution

Comparison of mineral dust and droplet residuals measured with two single particle aerosol mass spectrometers

NASA Astrophysics Data System (ADS)

Wonaschütz, Anna; Ludwig, Wolfgang; Zawadowicz, Maria; Hiranuma, Naruki; Hitzenberger, Regina; Cziczo, Daniel; DeMott, Paul; Möhler, Ottmar

2017-04-01

Single Particle mass spectrometers are used to gain information on the chemical composition of individual aerosol particles, aerosol mixing state, and other valuable aerosol characteristics. During the Mass Spectrometry Intercomparison at the Fifth Ice Nucleation (FIN-01) Workshop, the new LAAPTOF single particle aerosol mass spectrometer (AeroMegt GmbH) was conducting simultaneous measurements together with the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument. The aerosol particles were sampled from the AIDA chamber during ice cloud expansion experiments. Samples of mineral dust and ice droplet residuals were measured simultaneously. In this work, three expansion experiments are chosen for a comparison between the two mass spectrometers. A fuzzy clustering routine is used to group the spectra. Cluster centers describing the ensemble of particles are compared. First results show that while differences in the peak heights are likely due to the use of an amplifier in PALMS, cluster centers are comparable.

Derivation of Aerosol Columnar Mass from MODIS Optical Depth

NASA Technical Reports Server (NTRS)

Gasso, Santiago; Hegg, Dean A.

2003-01-01

In order to verify performance, aerosol transport models (ATM) compare aerosol columnar mass (ACM) with those derived from satellite measurements. The comparison is inherently indirect since satellites derive optical depths and they use a proportionality constant to derive the ACM. Analogously, ATMs output a four dimensional ACM distribution and the optical depth is linearly derived. In both cases, the proportionality constant requires a direct intervention of the user by prescribing the aerosol composition and size distribution. This study introduces a method that minimizes the direct user intervention by making use of the new aerosol products of MODIS. A parameterization is introduced for the derivation of columnar aerosol mass (AMC) and CCN concentration (CCNC) and comparisons between sunphotometer, MODIS Airborne Simulator (MAS) and in-measurements are shown. The method still relies on the scaling between AMC and optical depth but the proportionality constant is dependent on the MODIS derived r$_{eff}$,\\eta (contribution of the accumulation mode radiance to the total radiance), ambient RH and an assumed constant aerosol composition. The CCNC is derived fkom a recent parameterization of CCNC as a function of the retrieved aerosol volume. By comparing with in-situ data (ACE-2 and TARFOX campaigns), it is shown that retrievals in dry ambient conditions (dust) are improved when using a proportionality constant dependent on r$ {eff}$ and \\eta derived in the same pixel. In high humidity environments, the improvement inthe new method is inconclusive because of the difficulty in accounting for the uneven vertical distribution of relative humidity. Additionally, two detailed comparisons of AMC and CCNC retrieved by the MAS algorithm and the new method are shown. The new method and MAS retrievals of AMC are within the same order of magnitude with respect to the in-situ measurements of aerosol mass. However, the proposed method is closer to the in-situ measurements than

Aerosol mass spectrometry: particle-vaporizer interactions and their consequences for the measurements

NASA Astrophysics Data System (ADS)

Drewnick, F.; Diesch, J.-M.; Faber, P.; Borrmann, S.

2015-09-01

The Aerodyne aerosol mass spectrometer (AMS) is a frequently used instrument for on-line measurement of the ambient sub-micron aerosol composition. With the help of calibrations and a number of assumptions on the flash vaporization and electron impact ionization processes, this instrument provides robust quantitative information on various non-refractory ambient aerosol components. However, when measuring close to certain anthropogenic or marine sources of semi-refractory aerosols, several of these assumptions may not be met and measurement results might easily be incorrectly interpreted if not carefully analyzed for unique ions, isotope patterns, and potential slow vaporization associated with semi-refractory species. Here we discuss various aspects of the interaction of aerosol particles with the AMS tungsten vaporizer and the consequences for the measurement results: semi-refractory components - i.e., components that vaporize but do not flash-vaporize at the vaporizer and ionizer temperatures, like metal halides (e.g., chlorides, bromides or iodides of Al, Ba, Cd, Cu, Fe, Hg, K, Na, Pb, Sr, Zn) - can be measured semi-quantitatively despite their relatively slow vaporization from the vaporizer. Even though non-refractory components (e.g., NH4NO3 or (NH4)2SO4) vaporize quickly, under certain conditions their differences in vaporization kinetics can result in undesired biases in ion collection efficiency in thresholded measurements. Chemical reactions with oxygen from the aerosol flow can have an influence on the mass spectra for certain components (e.g., organic species). Finally, chemical reactions of the aerosol with the vaporizer surface can result in additional signals in the mass spectra (e.g., WO2Cl2-related signals from particulate Cl) and in conditioning or contamination of the vaporizer, with potential memory effects influencing the mass spectra of subsequent measurements. Laboratory experiments that investigate these particle-vaporizer interactions are

Pro-2-PAM Therapy for Central and Peripheral Cholinesterases

PubMed Central

DeMar, James C.; Clarkson, Edward D.; Ratcliffe, Ruthie H.; Campbell, Amy J.; Thangavelu, Sonia G.; Herdman, Christine A.; Leader, Haim; Schulz, Susan M.; Marek, Elizabeth; Medynets, Marie A.; Ku, Theresa C.; Evans, Sarah A.; Khan, Farhat A.; Owens, Roberta R.; Nambiar, Madhusoodana P.; Gordon, Richard K.

2010-01-01

Novel therapeutics to overcome the toxic effects of organophosphorus (OP) chemical agents are needed due to the documented use of OPs in warfare (e.g. 1980–1988 Iran/Iraq war) and terrorism (e.g. 1995 Tokyo subway attacks). Standard OP exposure therapy in the United States consists of atropine sulfate (to block muscarinic receptors), the acetylcholinesterase (AChE) reactivator (oxime) pralidoxime chloride (2-PAM), and a benzodiazepine anticonvulsant to ameliorate seizures. A major disadvantage is that quaternary nitrogen charged oximes, including 2-PAM, do not cross the blood brain barrier (BBB) to treat brain AChE. Therefore, we have synthesized and evaluated pro-2-PAM (a lipid permeable 2-PAM derivative) that can enter the brain and reactivate CNS AChE, preventing seizures in guinea pigs after exposure to OPs. The protective effects of the pro-2-PAM after OP exposure were shown using a) surgically-implanted radiotelemetry probes for electroencephalogram (EEG) b) neurohistopathology of brain, c) cholinesterase activities in the PNS and CNS, and d) survivability. The PNS oxime 2-PAM was ineffective at reducing seizures/status epilepticus (SE) in diisopropyl-fluorophosphate (DFP)-exposed animals. In contrast, pro-2-PAM significantly suppressed and then eliminated seizure activity. In OP-exposed guinea pigs, there was a significant reduction in neurological damage with pro-2-PAM, but not 2-PAM. Distinct regional areas of the brains showed significantly higher AChE activity 1.5 h after OP exposure in pro-2-PAM treated animals compared to the 2-PAM treated ones. However, blood and diaphragm showed similar AChE activities in animals treated with either oxime, as both 2-PAM and pro 2-PAM are PNS active oximes. In conclusion, pro-2-PAM can cross the BBB, is rapidly metabolized inside the brain to 2-PAM, and protects against OP-induced SE through restoration of brain AChE activity. Pro-2-PAM represents the first non-invasive means of administering a CNS therapeutic for

SAM-CAAM: A Concept for Acquiring Systematic Aircraft Measurements to Characterize Aerosol Air Masses.

PubMed

Kahn, Ralph A; Berkoff, Tim A; Brock, Charles; Chen, Gao; Ferrare, Richard A; Ghan, Steven; Hansico, Thomas F; Hegg, Dean A; Martins, J Vanderlei; McNaughton, Cameron S; Murphy, Daniel M; Ogren, John A; Penner, Joyce E; Pilewskie, Peter; Seinfeld, John H; Worsnop, Douglas R

2017-10-01

A modest operational program of systematic aircraft measurements can resolve key satellite-aerosol-data-record limitations. Satellite observations provide frequent, global aerosol-amount maps, but offer only loose aerosol property constraints needed for climate and air quality applications. We define and illustrate the feasibility of flying an aircraft payload to measure key aerosol optical, microphysical, and chemical properties in situ . The flight program could characterize major aerosol air-mass types statistically, at a level-of-detail unobtainable from space. It would: (1) enhance satellite aerosol retrieval products with better climatology assumptions, and (2) improve translation between satellite-retrieved optical properties and species-specific aerosol mass and size simulated in climate models to assess aerosol forcing, its anthropogenic components, and other environmental impacts. As such, Systematic Aircraft Measurements to Characterize Aerosol Air Masses (SAM-CAAM) could add value to data records representing several decades of aerosol observations from space, improve aerosol constraints on climate modeling , help interrelate remote-sensing, in situ, and modeling aerosol-type definitions , and contribute to future satellite aerosol missions. Fifteen Required Variables are identified, and four Payload Options of increasing ambition are defined, to constrain these quantities. "Option C" could meet all the SAM-CAAM objectives with about 20 instruments, most of which have flown before, but never routinely several times per week, and never as a group. Aircraft integration, and approaches to data handling, payload support, and logistical considerations for a long-term, operational mission are discussed. SAM-CAAM is feasible because, for most aerosol sources and specified seasons, particle properties tend to be repeatable , even if aerosol loading varies.

Aerosol chemical composition in cloud events by high resolution time-of-flight aerosol mass spectrometry.

PubMed

Hao, Liqing; Romakkaniemi, Sami; Kortelainen, Aki; Jaatinen, Antti; Portin, Harri; Miettinen, Pasi; Komppula, Mika; Leskinen, Ari; Virtanen, Annele; Smith, James N; Sueper, Donna; Worsnop, Douglas R; Lehtinen, Kari E J; Laaksonen, Ari

2013-03-19

This study presents results of direct observations of aerosol chemical composition in clouds. A high-resolution time-of-flight aerosol mass spectrometer was used to make measurements of cloud interstitial particles (INT) and mixed cloud interstitial and droplet residual particles (TOT). The differences between these two are the cloud droplet residuals (RES). Positive matrix factorization analysis of high-resolution mass spectral data sets and theoretical calculations were performed to yield distributions of chemical composition of the INT and RES particles. We observed that less oxidized hydrocarbon-like organic aerosols (HOA) were mainly distributed into the INT particles, whereas more oxidized low-volatile oxygenated OA (LVOOA) mainly in the RES particles. Nitrates existed as organic nitrate and in chemical form of NH(4)NO(3). Organic nitrates accounted for 45% of total nitrates in the INT particles, in clear contrast to 26% in the RES particles. Meanwhile, sulfates coexist in forms of acidic NH(4)HSO(4) and neutralized (NH(4))(2)SO(4). Acidic sulfate made up 64.8% of total sulfates in the INT particles, much higher than 10.7% in the RES particles. The results indicate a possible joint effect of activation ability of aerosol particles, cloud processing, and particle size effects on cloud formation.

A rocket-borne mass analyzer for charged aerosol particles in the mesosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knappmiller, Scott; Robertson, Scott; Sternovsky, Zoltan

2008-10-15

An electrostatic mass spectrometer for nanometer-sized charged aerosol particles in the mesosphere has been developed and tested. The analyzer is mounted on the forward end of a rocket and has a slit opening for admitting a continuous sample of air that is exhausted through ports at the sides. Within the instrument housing are two sets of four collection plates that are biased with positive and negative voltages for the collection of negative and positive aerosol particles, respectively. Each collection plate spans about an order of magnitude in mass which corresponds to a factor of 2 in radius. The number densitymore » of the charge is calculated from the current collected by the plates. The mean free path for molecular collisions in the mesosphere is comparable to the size of the instrument opening; thus, the analyzer performance is modeled by a Monte Carlo computer code that finds the aerosol particles trajectories within the instrument including both the electrostatic force and the forces from collisions of the aerosol particles with air molecules. Mass sensitivity curves obtained using the computer models are near to those obtained in the laboratory using an ion source. The first two flights of the instrument returned data showing the charge number densities of both positive and negative aerosol particles in four mass ranges.« less

Source contributions to black carbon mass fractions in aerosol particles over the northwestern Pacific

NASA Astrophysics Data System (ADS)

Koga, Seizi; Maeda, Takahisa; Kaneyasu, Naoki

Aerosol particle number size distributions above 0.3 μm in diameter and black carbon mass concentrations in aerosols were observed on Chichi-jima of the Ogasawara Islands in the northwestern Pacific from January 2000 to December 2002. Chichi-jima is suitable to observe polluted air masses from East Asia in winter and clean air masses over the western North Pacific in summer. In winter, aerosols over Chichi-jima were strongly affected by anthropogenic emissions in East Asia. The form of energy consumption in East Asia varies in various regions. Hence, each source region is expected to be characterized by an individual black carbon mass fraction. A three-dimensional Eulerian transport model was used to estimate contribution rates to air pollutants from each source region in East Asia. Because the Miyake-jima eruption began at the end of June 2000, the influence of smokes from Miyake-jima was also considered in the model calculation. The results of model calculations represent what must be noticed about smokes from volcanoes including Miyake-jima to interpret temporal variations of sulfur compounds over the northwestern Pacific. To evaluate black carbon mass fractions in anthropogenic aerosols as a function of source region, the relationships between the volume concentration of aerosol particles and the black carbon mass concentration in the winter were classified under each source region in East Asia. Consequently, the black carbon mass fractions in aerosols from China, Japan and the Korean Peninsula, and other regions were estimated to be 9-13%, 5-7%, and 4-5%, respectively.

A CLOSURE STUDY OF AEROSOL MASS CONCENTRATION MEASUREMENTS: COMPARISON OF VALUES OBTAINED WITH FILTERS AND BY DIRECT MEASUREMENTS OF MASS DISTRIBUTIONS. (R826372)

EPA Science Inventory

We compare measurements of aerosol mass concentrations obtained gravimetrically using Teflon coated glass fiber filters and by integrating mass distributions measured with the differential mobility analyzer–aerosol particle mass analyzer (DMA–APM) technique (Aero...

Effect of Vaporizer Temperature on Ambient Non-Refractory Submicron Aerosol Composition and Mass Spectra Measured by the Aerosol Mass Spectrometer

EPA Science Inventory

Aerodyne Aerosol Mass Spectrometers (AMS) are routinely operated with a constant vaporizer temperature (Tvap) of 600^oC in order to facilitate quantitative detection of non-refractory submicron (NR-PM1) species. By analogy with other thermal desorption instrument...

Changes in organic aerosol composition with aging inferred from aerosol mass spectra

NASA Astrophysics Data System (ADS)

Ng, N. L.; Canagaratna, M. R.; Jimenez, J. L.; Chhabra, P. S.; Seinfeld, J. H.; Worsnop, D. R.

2011-03-01

Organic aerosols (OA) can be separated with factor analysis of aerosol mass spectrometer (AMS) data into hydrocarbon-like OA (HOA) and oxygenated OA (OOA). We develop a new method to parameterize H:C of OOA in terms of f43 (ratio of m/z 43, mostly C2H3O+, to total signal in the component mass spectrum). Such parameterization allows the transformation of large database of ambient OOA components from the f44 (mostly CO2+, likely from acid groups) vs. f43 space ("triangle plot") (Ng et al., 2010) into the Van Krevelen diagram (H:C vs. O:C). Heald et al. (2010) suggested that the bulk composition of OA line up in the Van Krevelen diagram with a slope ~ -1; such slope can potentially arise from the physical mixing of HOA and OOA, and/or from chemical aging of these components. In this study, we find that the OOA components from all sites occupy an area in the Van Krevelen space, with the evolution of OOA following a shallower slope of ~ -0.5, consistent with the additions of both acid and alcohol functional groups without fragmentation, and/or the addition of acid groups with C-C bond breakage. The importance of acid formation in OOA evolution is consistent with increasing f44 in the triangle plot with photochemical age. These results provide a framework for linking the bulk aerosol chemical composition evolution to molecular-level studies.

Determination of mixing state and sources of wintertime organic aerosol in Paris using single particle mass spectrometry

NASA Astrophysics Data System (ADS)

Healy, R. M.; Sciare, J.; Poulain, L.; Wiedensohler, A.; Jeong, C.; McGuire, M.; Evans, G. J.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J.

2012-12-01

The size-resolved chemical composition of single particles at an urban background site in Paris, France, was determined using an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) as part of the MEGAPOLI winter campaign in January/February 2010. A variety of mixing states were identified for organic aerosol by mass spectral clustering and apportioned to both fossil fuel and biomass burning sources. The ATOFMS data were scaled in order to produce mass concentration estimates for each organic aerosol particle type identified. Potassium-containing organic aerosol internally mixed with nitrate, associated with local wood burning, was observed to dominate during periods characterised by marine air masses. Sulfate-rich potassium-containing organic aerosol, associated with transboundary transport of biomass burning emissions, dominated during periods influenced by continental air masses. The scaled total mass concentration for potassium-containing particles was well correlated (R2 = 0.79) with concurrent measurements of potassium mass concentration measured with a Particle-Into-Liquid-Sampler (PILS). Another organic particle type, also containing potassium but rich in trimethylamine and sulfate, was detected exclusively during continental air mass events. These particles are postulated to have accumulated gas phase trimethylamine through heterogeneous reaction before arriving at the sampling site. Potential source regions for transboundary organic aerosols have been investigated using the potential source contribution function (PSCF). Comparison with aerosol mass spectrometer (AMS) measurements will also be discussed.

Real-time analysis of ambient organic aerosols using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

NASA Astrophysics Data System (ADS)

Brüggemann, Martin; Karu, Einar; Stelzer, Torsten; Hoffmann, Thorsten

2015-04-01

Organic aerosol accounts for a major fraction of atmospheric aerosols and has implications on the earth's climate and human health. However, due to the chemical complexity its measurement remains a major challenge for analytical instrumentation.1 Here, we present the development, characterization and application of a new soft ionization technique that allows mass spectrometric real-time detection of organic compounds in ambient aerosols. The aerosol flowing atmospheric-pressure afterglow (AeroFAPA) ion source utilizes a helium glow discharge plasma to produce excited helium species and primary reagent ions. Ionization of the analytes occurs in the afterglow region after thermal desorption and results mainly in intact molecular ions, facilitating the interpretation of the acquired mass spectra. In the past, similar approaches were used to detect pesticides, explosives or illicit drugs on a variety of surfaces.2,3 In contrast, the AeroFAPA source operates 'online' and allows the detection of organic compounds in aerosols without a prior precipitation or sampling step. To our knowledge, this is the first application of an atmospheric-pressure glow discharge ionization technique to ambient aerosol samples. We illustrate that changes in aerosol composition and concentration are detected on the time scale of seconds and in the ng-m-3 range. Additionally, the successful application of AeroFAPA-MS during a field study in a mixed forest region in Central Europe is presented. Several oxidation products of monoterpenes were clearly identified using the possibility to perform tandem MS experiments. The acquired data are in agreement with previous studies and demonstrate that AeroFAPA-MS is a suitable tool for organic aerosol analysis. Furthermore, these results reveal the potential of this technique to enable new insights into aerosol formation, growth and transformation in the atmosphere. References: 1) IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The

MASS SPECTROMETRY OF INDIVIDUAL AEROSOL PARTICLES. (R823980)

EPA Science Inventory

Typically, in real-time aerosol mass spectrometry (RTAMS), individual airborne particles
are ablated and ionized with a single focused laser pulse. This technique yields information that
permits bulk characterization of the particle, but information about the particle's sur...

Fully Automated Data Collection Using PAM and the Development of PAM/SPACE Reversible Cassettes

NASA Astrophysics Data System (ADS)

Hiraki, Masahiko; Watanabe, Shokei; Chavas, Leonard M. G.; Yamada, Yusuke; Matsugaki, Naohiro; Igarashi, Noriyuki; Wakatsuki, Soichi; Fujihashi, Masahiro; Miki, Kunio; Baba, Seiki; Ueno, Go; Yamamoto, Masaki; Suzuki, Mamoru; Nakagawa, Atsushi; Watanabe, Nobuhisa; Tanaka, Isao

2010-06-01

To remotely control and automatically collect data in high-throughput X-ray data collection experiments, the Structural Biology Research Center at the Photon Factory (PF) developed and installed sample exchange robots PAM (PF Automated Mounting system) at PF macromolecular crystallography beamlines; BL-5A, BL-17A, AR-NW12A and AR-NE3A. We developed and installed software that manages the flow of the automated X-ray experiments; sample exchanges, loop-centering and X-ray diffraction data collection. The fully automated data collection function has been available since February 2009. To identify sample cassettes, PAM employs a two-dimensional bar code reader. New beamlines, BL-1A at the Photon Factory and BL32XU at SPring-8, are currently under construction as part of Targeted Proteins Research Program (TPRP) by the Ministry of Education, Culture, Sports, Science and Technology of Japan. However, different robots, PAM and SPACE (SPring-8 Precise Automatic Cryo-sample Exchanger), will be installed at BL-1A and BL32XU, respectively. For the convenience of the users of both facilities, pins and cassettes for PAM and SPACE are developed as part of the TPRP.

Secondary Organic Aerosol Production from Gasoline Vehicle Exhaust: Effects of Engine Technology, Cold Start, and Emission Certification Standard.

PubMed

Zhao, Yunliang; Lambe, Andrew T; Saleh, Rawad; Saliba, Georges; Robinson, Allen L

2018-02-06

Secondary organic aerosol (SOA) formation from dilute exhaust from 16 gasoline vehicles was investigated using a potential aerosol mass (PAM) oxidation flow reactor during chassis dynamometer testing using the cold-start unified cycle (UC). Ten vehicles were equipped with gasoline direct injection engines (GDI vehicles) and six with port fuel injection engines (PFI vehicles) certified to a wide range of emissions standards. We measured similar SOA production from GDI and PFI vehicles certified to the same emissions standard; less SOA production from vehicles certified to stricter emissions standards; and, after accounting for differences in gas-particle partitioning, similar effective SOA yields across different engine technologies and certification standards. Therefore the ongoing, dramatic shift from PFI to GDI vehicles in the United States should not alter the contribution of gasoline vehicles to ambient SOA and the natural replacement of older vehicles with newer ones certified to stricter emissions standards should reduce atmospheric SOA levels. Compared to hot operations, cold-start exhaust had lower effective SOA yields, but still contributed more SOA overall because of substantially higher organic gas emissions. We demonstrate that the PAM reactor can be used as a screening tool for vehicle SOA production by carefully accounting for the effects of the large variations in emission rates.

Satellite measurements of aerosol mass and transport

NASA Technical Reports Server (NTRS)

Fraser, R. S.; Kaufman, Y. J.; Mahoney, R. L.

1984-01-01

The aerosol optical thickness over land is derived from satellite measurements of the radiance of scattered sunlight. These data are used to estimate the columnar mass density of particulate sulfur on a day with a large amount of sulfur. The horizontal transport of the particulate sulfur is calculated using wind vectors measured with rawins.

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

NASA Technical Reports Server (NTRS)

Kahn, Ralph A.

2012-01-01

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

[Research progress on wind erosion control with polyacrylamide (PAM).

PubMed

Li, Yuan Yuan; Wang, Zhan Li

2016-03-01

Soil wind erosion is one of the main reasons for soil degradation in the northwest region of China. Polyacrylamide (PAM), as an efficient soil amendment, has gained extensive attention in recent years since it is effective in improving the structure of surface soil due to its special physical and chemical properties. This paper introduced the physical and chemical properties of PAM, reviewed the effects of PAM on soil wind erosion amount and threshold wind velocity, as well as the effect differences of PAM in soil wind erosion control under conditions of various methods and doses. Its effect was proved by comparing with other materials in detail. Furthermore, we analyzed the mecha-nism of wind erosion control with PAM according to its influence on soil physical characteristics. Comprehensive analysis showed that, although some problems existed in wind erosion control with (PAM), PAM as a sand fixation agent, can not only enhance the capacity of the soil resis-tance to wind erosion, but also improve soil physical properties to form better soil conditions. Besides, we proposed that combination of PAM and plant growth would increase the survival rate of plants greatly, control soil wind erosion in wind-erosive areas, and improve the quality of the ecological environment construction. Thus, PAM has practically important significance and wide application prospect in controlling soil wind erosion.

Chemical characteristics of submicron particles at the central Tibetan Plateau: insights from aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Xu, Jianzhong; Zhang, Qi; Shi, Jinsen; Ge, Xinlei; Xie, Conghui; Wang, Junfeng; Kang, Shichang; Zhang, Ruixiong; Wang, Yuhang

2018-01-01

Recent studies have revealed a significant influx of anthropogenic aerosol from South Asia to the Himalayas and Tibetan Plateau (TP) during pre-monsoon period. In order to characterize the chemical composition, sources, and transport processes of aerosol in this area, we carried out a field study during June 2015 by deploying a suite of online instruments including an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) and a multi-angle absorption photometer (MAAP) at Nam Co station (90°57' E, 30°46' N; 4730 m a.s.l.) at the central of the TP. The measurements were made at a period when the transition from pre-monsoon to monsoon occurred. The average ambient mass concentration of submicron particulate matter (PM1) over the whole campaign was ˜ 2.0 µg m-3, with organics accounting for 68 %, followed by sulfate (15 %), black carbon (8 %), ammonium (7 %), and nitrate (2 %). Relatively higher aerosol mass concentration episodes were observed during the pre-monsoon period, whereas persistently low aerosol concentrations were observed during the monsoon period. However, the chemical composition of aerosol during the higher aerosol concentration episodes in the pre-monsoon season was on a case-by-case basis, depending on the prevailing meteorological conditions and air mass transport routes. Most of the chemical species exhibited significant diurnal variations with higher values occurring during afternoon and lower values during early morning, whereas nitrate peaked during early morning in association with higher relative humidity and lower air temperature. Organic aerosol (OA), with an oxygen-to-carbon ratio (O / C) of 0.94, was more oxidized during the pre-monsoon period than during monsoon (average O / C ratio of 0.72), and an average O / C was 0.88 over the entire campaign period, suggesting overall highly oxygenated aerosol in the central TP. Positive matrix factorization of the high-resolution mass spectra of OA identified two oxygenated

The link between organic aerosol mass loading and degree of oxygenation: an α-pinene photooxidation study

NASA Astrophysics Data System (ADS)

Pfaffenberger, L.; Barmet, P.; Slowik, J. G.; Praplan, A. P.; Dommen, J.; Prévôt, A. S. H.; Baltensperger, U.

2013-07-01

A series of smog chamber (SC) experiments was conducted to identify factors responsible for the discrepancy between ambient and SC aerosol degree of oxygenation. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer is used to compare mass spectra from α-pinene photooxidation with ambient aerosol. Composition is compared in terms of the fraction of particulate CO2+, a surrogate for carboxylic acids, vs. the fraction of C2H3O+, a surrogate for aldehydes, alcohols and ketones, as well as in the Van Krevelen space, where the evolution of the atomic hydrogen-to-carbon ratio (H : C) vs. the atomic oxygen-to-carbon ratio (O : C) is investigated. Low (near-ambient) organic mass concentrations were found to be necessary to obtain oxygenation levels similar to those of low-volatility oxygenated organic aerosol (LV-OOA) commonly identified in ambient measurements. The effects of organic mass loading and OH (hydroxyl radical) exposure were decoupled by inter-experiment comparisons at the same integrated OH concentration. An OH exposure between 3 and 25 × 107 cm-3 h is needed to increase O : C by 0.05 during aerosol aging. For the first time, LV-OOA-like aerosol from the abundant biogenic precursor α-pinene was produced in a smog chamber by oxidation at typical atmospheric OH concentrations. Significant correlation between measured secondary organic aerosol (SOA) and reference LV-OOA mass spectra is shown by Pearson's R2 values larger than 0.90 for experiments with low organic mass concentrations between 1.2 and 18 μg m-3 at an OH exposure of 4 × 107 cm-3 h, corresponding to about two days of oxidation time in the atmosphere, based on a global mean OH concentration of ~ 1 × 106 cm-3. α-Pinene SOA is more oxygenated at low organic mass loadings. Because the degree of oxygenation influences the chemical, volatility and hygroscopic properties of ambient aerosol, smog chamber studies must be performed at near-ambient concentrations to accurately simulate

Aircraft-based Aerosol Size and Composition Measurements during ACE-Asia and CRYSTAL-FACE using an Aerodyne Aerosol Mass Spectrometer

NASA Astrophysics Data System (ADS)

Bahreini, R.; Jimenez, J.; Delia, A.; Flagan, R. C.; Seinfeld, J. H.; Jayne, J. T.; Worsnop, D. R.

2002-12-01

An Aerodyne Aerosol Mass Spectrometer (AMS) was deployed in an aircraft for the first time during the ACE-Asia field campaign. The AMS was operated on board the CIRPAS Twin Otter aircraft to measure the size-resolved chemical composition of the submicron aerosols in the outflow from Eastern Asia. Research flights were carried out from March 31 to May 1, 2001 in an area that covered 127 E-135 E and 32 N-38 N on longitude and latitude, respectively. The submicron aerosol was typically distributed in distinct layers (from the boundary layer to ~ 3700 m). This is consistent with other on-board measurements. The aerosol in the pollution layers was mainly composed of sulfate, ammonium, and organics separated by cleaner layers. Sub-micron nitrate aerosols were also detected in some layers. Since the molar ratio of positive to negative ions did not exceed one on most of the constant altitude legs of the flights, the particles were not completely neutralized. Sulfate and organics concentrations of up to 10 and 5 ug m-3 (STP), respectively, were measured on some pollution layers. AMS measurements of sulfate concentration and NH4/SO4 mass ratio (~0.16 on average) are consistent with previously reported measurements at Cheju Island, South Korea [Charmichael et al., 1997; Chen et al., 1997] and Sapporo, Japan [Kaneyasu et al., 1995]. The mass-weighed size distribution of the sub-micron sulfate was relatively constant from day to day and layer to layer, with an aerodynamic mode at 350-500 nm (vacuum aerodynamic diameter) and FWHM ~ 400 nm on most of the layers. Furthermore, the ratios between SO4/ NH4/ NO3/ Organics were approximately independent of size in the sub-micron size range. Comparisons of AMS data to other on-board aerosol measurements will be presented. In particular, the AMS mass concentration correlates well with the aerosol volume determined by the on-board Differential Automated Classifying Aerosol Detector (DCAD). In addition, preliminary results of airborne size

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

PubMed

Ku, Bon Ki; Evans, Douglas E

2012-04-01

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

SAM-CAAM: A Concept for Acquiring Systematic Aircraft Measurements to Characterize Aerosol Air Masses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kahn, Ralph A.; Berkoff, Tim A.; Brock, Charles

A modest operational program of systematic aircraft measurements can resolve key satellite aerosol data record limitations. Satellite observations provide frequent global aerosol amount maps but offer only loose aerosol property constraints needed for climate and air quality applications. In this paper, we define and illustrate the feasibility of flying an aircraft payload to measure key aerosol optical, microphysical, and chemical properties in situ. The flight program could characterize major aerosol airmass types statistically, at a level of detail unobtainable from space. It would 1) enhance satellite aerosol retrieval products with better climatology assumptions and 2) improve translation between satellite-retrieved opticalmore » properties and species-specific aerosol mass and size simulated in climate models to assess aerosol forcing, its anthropogenic components, and other environmental impacts. As such, Systematic Aircraft Measurements to Characterize Aerosol Air Masses (SAM-CAAM) could add value to data records representing several decades of aerosol observations from space; improve aerosol constraints on climate modeling; help interrelate remote sensing, in situ, and modeling aerosol-type definitions; and contribute to future satellite aerosol missions. Fifteen required variables are identified and four payload options of increasing ambition are defined to constrain these quantities. “Option C” could meet all the SAM-CAAM objectives with about 20 instruments, most of which have flown before, but never routinely several times per week, and never as a group. Aircraft integration and approaches to data handling, payload support, and logistical considerations for a long-term, operational mission are discussed. Finally, SAM-CAAM is feasible because, for most aerosol sources and specified seasons, particle properties tend to be repeatable, even if aerosol loading varies.« less

SAM-CAAM: A Concept for Acquiring Systematic Aircraft Measurements to Characterize Aerosol Air Masses

DOE PAGES

Kahn, Ralph A.; Berkoff, Tim A.; Brock, Charles; ...

2017-10-30

A modest operational program of systematic aircraft measurements can resolve key satellite aerosol data record limitations. Satellite observations provide frequent global aerosol amount maps but offer only loose aerosol property constraints needed for climate and air quality applications. In this paper, we define and illustrate the feasibility of flying an aircraft payload to measure key aerosol optical, microphysical, and chemical properties in situ. The flight program could characterize major aerosol airmass types statistically, at a level of detail unobtainable from space. It would 1) enhance satellite aerosol retrieval products with better climatology assumptions and 2) improve translation between satellite-retrieved opticalmore » properties and species-specific aerosol mass and size simulated in climate models to assess aerosol forcing, its anthropogenic components, and other environmental impacts. As such, Systematic Aircraft Measurements to Characterize Aerosol Air Masses (SAM-CAAM) could add value to data records representing several decades of aerosol observations from space; improve aerosol constraints on climate modeling; help interrelate remote sensing, in situ, and modeling aerosol-type definitions; and contribute to future satellite aerosol missions. Fifteen required variables are identified and four payload options of increasing ambition are defined to constrain these quantities. “Option C” could meet all the SAM-CAAM objectives with about 20 instruments, most of which have flown before, but never routinely several times per week, and never as a group. Aircraft integration and approaches to data handling, payload support, and logistical considerations for a long-term, operational mission are discussed. Finally, SAM-CAAM is feasible because, for most aerosol sources and specified seasons, particle properties tend to be repeatable, even if aerosol loading varies.« less

Evaluation of species-dependent detection efficiencies in the aerosol mass spectrometer

USDA-ARS?s Scientific Manuscript database

Mass concentrations of chemical species calculated from the aerosol mass spectrometer (AMS) depend on two factors: particle collection efficiency (CE) and relative ionization efficiency (RIE, relative to the primary calibrant ammonium nitrate). While previous studies have characterized CE, RIE is re...

Mass-spectrometric identification of primary biological particle markers and application to pristine submicron aerosol measurements in Amazonia

NASA Astrophysics Data System (ADS)

Schneider, J.; Freutel, F.; Zorn, S. R.; Chen, Q.; Farmer, D. K.; Jimenez, J. L.; Martin, S. T.; Artaxo, P.; Wiedensohler, A.; Borrmann, S.

2011-11-01

The detection of primary biological material in submicron aerosol by means of thermal desorption/electron impact ionization aerosol mass spectrometry was investigated. Mass spectra of amino acids, carbohydrates, small peptides, and proteins, all of which are key building blocks of biological particles, were recorded in laboratory experiments. Several characteristic marker fragments were identified. The intensity of the marker signals relative to the total organic mass spectrum allows for an estimation of the content of primary biological material in ambient organic aerosol. The developed method was applied to mass spectra recorded during AMAZE-08, a field campaign conducted in the pristine rainforest of the central Amazon Basin, Brazil, during the wet season of February and March 2008. The low abundance of identified marker fragments places upper limits of 7.5% for amino acids and 5.6% for carbohydrates on the contribution of primary biological aerosol particles (PBAP) to the submicron organic aerosol mass concentration during this time period. Upper limits for the absolute submicron concentrations for both compound classes range from 0.01 to 0.1 μg m-3. Carbohydrates and proteins (composed of amino acids) make up for about two thirds of the dry mass of a biological cell. Thus, our findings suggest an upper limit for the PBAP mass fraction of about 20% to the submicron organic aerosol measured in Amazonia during AMAZE-08.

Measurements of Organic Composition of Aerosol and Rainwater Samples Using Offline Aerosol Mass Spectrometry

NASA Astrophysics Data System (ADS)

OBrien, R. E.; Ridley, K. J.; Canagaratna, M. R.; Croteau, P.; Budisulistiorini, S. H.; Cui, T.; Green, H. S.; Surratt, J. D.; Jayne, J. T.; Kroll, J. H.

2016-12-01

A thorough understanding of the sources, evolution, and budgets of atmospheric organic aerosol requires widespread measurements of the amount and chemical composition of atmospheric organic carbon in the condensed phase (within particles and water droplets). Collecting such datasets requires substantial spatial and temporal (long term) coverage, which can be challenging when relying on online measurements by state-of-the-art research-grade instrumentation (such as those used in atmospheric chemistry field studies). Instead, samples are routinely collected using relatively low-cost techniques, such as aerosol filters, for offline analysis of their chemical composition. However, measurements made by online and offline instruments can be fundamentally different, leading to disparities between data from field studies and those from more routine monitoring. To better connect these two approaches, and take advantage of the benefits of each, we have developed a method to introduce collected samples into online aerosol instruments using nebulization. Because nebulizers typically require tens to hundreds of milliliters of solution, limiting this technique to large samples, we developed a new, ultrasonic micro-nebulizer that requires only small volumes (tens of microliters) of sample for chemical analysis. The nebulized (resuspended) sample is then sent into a high-resolution Aerosol Mass Spectrometer (AMS), a widely-used instrument that provides key information on the chemical composition of aerosol particulate matter (elemental ratios, carbon oxidation state, etc.), measurements that are not typically made for collected atmospheric samples. Here, we compare AMS data collected using standard on-line techniques with our offline analysis, demonstrating the utility of this new technique to aerosol filter samples. We then apply this approach to organic aerosol filter samples collected in remote regions, as well as rainwater samples from across the US. This data provides

Quantitative determination of carbonaceous particle mixing state in Paris using single particle mass spectrometer and aerosol mass spectrometer measurements

NASA Astrophysics Data System (ADS)

Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

2013-04-01

Single particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been estimated using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulphate and potassium were compared with concurrent measurements from an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal/optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and ten discrete mixing states for carbonaceous particles were identified and quantified. Potassium content was used to identify particles associated with biomass combustion. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorization, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulphate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA/EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidized OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the heterogeneity of primary and

Quantitative determination of carbonaceous particle mixing state in Paris using single-particle mass spectrometer and aerosol mass spectrometer measurements

NASA Astrophysics Data System (ADS)

Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

2013-09-01

Single-particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single-particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been determined using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulfate and potassium were compared with concurrent measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal-optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived estimated mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and 10 discrete mixing states for carbonaceous particles were identified and quantified. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorisation, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulfate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA / EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidised OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the range of primary and secondary organic aerosol mixing states in Paris. Examination of the temporal

Reactions and mass spectra of complex particles using Aerosol CIMS

NASA Astrophysics Data System (ADS)

Hearn, John D.; Smith, Geoffrey D.

2006-12-01

Aerosol chemical ionization mass spectrometry (CIMS) is used both on- and off-line for the analysis of complex laboratory-generated and ambient particles. One of the primary advantages of Aerosol CIMS is the low degree of ion fragmentation, making this technique well suited for investigating the reactivity of complex particles. To demonstrate the usefulness of this "soft" ionization, particles generated from meat cooking were reacted with ozone and the composition was monitored as a function of reaction time. Two distinct kinetic regimes were observed with most of the oleic acid in these particles reacting quickly but with 30% appearing to be trapped in the complex mixture. Additionally, detection limits are measured to be sufficiently low (100-200 ng/m3) to detect some of the more abundant constituents in ambient particles, including sulfate, which is measured in real-time at 1.2 [mu]g/m3. To better characterize complex aerosols from a variety of sources, a novel off-line collection method was also developed in which non-volatile and semi-volatile organics are desorbed from particles and concentrated in a cold U-tube. Desorption from the U-tube followed by analysis with Aerosol CIMS revealed significant amounts of nicotine in cigarette smoke and levoglucosan in oak and pine smoke, suggesting that this may be a useful technique for monitoring particle tracer species. Additionally, secondary organic aerosol formed from the reaction of ozone with R-limonene and volatile organics from orange peel were analyzed off-line showing large molecular weight products (m/z > 300 amu) that may indicate the formation of oligomers. Finally, mass spectra of ambient aerosol collected offline reveal a complex mixture of what appears to be highly processed organics, some of which may contain nitrogen.

Complementary online aerosol mass spectrometry and offline FT-IR spectroscopy measurements: Prospects and challenges for the analysis of anthropogenic aerosol particle emissions

NASA Astrophysics Data System (ADS)

Faber, Peter; Drewnick, Frank; Bierl, Reinhard; Borrmann, Stephan

2017-10-01

The aerosol mass spectrometer (AMS) is well established in investigating highly time-resolved dynamics of submicron aerosol chemical composition including organic aerosol (OA). However, interpretation of mass spectra on molecular level is limited due to strong fragmentation of organic substances and potential reactions inside the AMS ion chamber. Results from complementary filter-based FT-IR absorption measurements were used to explain features in high-resolution AMS mass spectra of different types of OA (e.g. cooking OA, cigarette smoking OA, wood burning OA). Using this approach some AMS fragment ions were validated in this study as appropriate and rather specific markers for a certain class of organic compounds for all particle types under investigation. These markers can therefore be used to get deeper insights in the chemical composition of OA based on AMS mass spectra in upcoming studies. However, the specificity of other fragment ions such as C2H4O2+ (m/z 60.02114) remains ambiguous. In such cases, complementary FT-IR measurements allow the interpretation of highly time-resolved AMS mass spectra at the level of molecular functional groups. Furthermore, this study discusses the challenges in reducing inorganic interferences (e.g. from water and ammonium salts) in FT-IR spectra of atmospheric aerosols to decrease spectral uncertainties for better comparisons and, thus, to get more robust results.

Development and characterization of an aircraft aerosol time-of-flight mass spectrometer.

PubMed

Pratt, Kerri A; Mayer, Joseph E; Holecek, John C; Moffet, Ryan C; Sanchez, Rene O; Rebotier, Thomas P; Furutani, Hiroshi; Gonin, Marc; Fuhrer, Katrin; Su, Yongxuan; Guazzotti, Sergio; Prather, Kimberly A

2009-03-01

Vertical and horizontal profiles of atmospheric aerosols are necessary for understanding the impact of air pollution on regional and global climate. To gain further insight into the size-resolved chemistry of individual atmospheric particles, a smaller aerosol time-of-flight mass spectrometer (ATOFMS) with increased data acquisition capabilities was developed for aircraft-based studies. Compared to previous ATOFMS systems, the new instrument has a faster data acquisition rate with improved ion transmission and mass resolution, as well as reduced physical size and power consumption, all required advances for use in aircraft studies. In addition, real-time source apportionment software allows the immediate identification and classification of individual particles to guide sampling decisions while in the field. The aircraft (A)-ATOFMS was field-tested on the ground during the Study of Organic Aerosols in Riverside, CA (SOAR) and aboard an aircraft during the Ice in Clouds Experiment-Layer Clouds (ICE-L). Initial results from ICE-L represent the first reported aircraft-based single-particle dual-polarity mass spectrometry measurements and provide an increased understanding of particle mixing state as a function of altitude. Improved ion transmission allows for the first single-particle detection of species out to approximately m/z 2000, an important mass range for the detection of biological aerosols and oligomeric species. In addition, high time resolution measurements of single-particle mixing state are demonstrated and shown to be important for airborne studies where particle concentrations and chemistry vary rapidly.

Characterization of aerosol composition, concentrations, and sources at Baengnyeong Island, Korea using an aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Lee, Taehyoung; Choi, Jinsoo; Lee, Gangwoong; Ahn, Junyoung; Park, Jin Soo; Atwood, Samuel A.; Schurman, Misha; Choi, Yongjoo; Chung, Yoomi; Collett, Jeffrey L.

2015-11-01

To improve understanding of the sources and chemical properties of particulate pollutants on the western side of the Korean Peninsula, an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) measured non-refractory fine (PM1) particles from May to November, 2011 at Baengnyeong Island, South Korea. Organic matter and sulfate were generally the most abundant species and exhibited maximum concentrations of 36 μg/m3 and 39 μg/m3, respectively. Nitrate concentrations peaked at 32 μg/m3 but were typically much lower than sulfate and organic matter concentrations. May, September, October, and November featured the highest monthly average concentrations, with lower concentrations typically observed from June through August. Potential source contribution function (PSCF) analysis and individual case studies revealed that transport from eastern China, an area with high SO2 emissions, was associated with high particulate sulfate concentrations at the measurement site. Observed sulfate aerosol sometimes was fully neutralized by ammonium but often was acidic; the average ammonium to sulfate molar ratio was 1.49. Measured species size distributions revealed a range of sulfate particle size distributions with modes between 100 and 600 nm. Organic aerosol source regions were widespread, including contributions from eastern China and South Korea. Positive matrix factorization (PMF) analysis indicated three "factors," or types of organic aerosol, comprising one primary, hydrocarbon-like organic aerosol (HOA) and two oxidized organic aerosol (OOA) components, including a more oxidized (MO-OOA) and a less oxidized (LO-OOA) oxidized organic aerosol. On average, HOA and OOA contributed 21% and 79% of the organic mass (OM), respectively, with the MO-OOA fraction nearly three times as abundant as the LO-OOA fraction. Biomass burning contributions to observed OM were low during the late spring/early summer agricultural burning season in eastern China, since

Characterizing source fingerprints and ageing processes in laboratory-generated secondary organic aerosols using proton-nuclear magnetic resonance (1H-NMR) analysis and HPLC HULIS determination

NASA Astrophysics Data System (ADS)

Zanca, Nicola; Lambe, Andrew T.; Massoli, Paola; Paglione, Marco; Croasdale, David R.; Parmar, Yatish; Tagliavini, Emilio; Gilardoni, Stefania; Decesari, Stefano

2017-09-01

The study of secondary organic aerosol (SOA) in laboratory settings has greatly increased our knowledge of the diverse chemical processes and environmental conditions responsible for the formation of particulate matter starting from biogenic and anthropogenic volatile compounds. However, characteristics of the different experimental setups and the way they impact the composition and the timescale of formation of SOA are still subject to debate. In this study, SOA samples were generated using a potential aerosol mass (PAM) oxidation flow reactor using α-pinene, naphthalene and isoprene as precursors. The PAM reactor facilitated exploration of SOA composition over atmospherically relevant photochemical ageing timescales that are unattainable in environmental chambers. The SOA samples were analyzed using two state-of-the-art analytical techniques for SOA characterization - proton nuclear magnetic resonance (1H-NMR) spectroscopy and HPLC determination of humic-like substances (HULIS). Results were compared with previous Aerodyne aerosol mass spectrometer (AMS) measurements. The combined 1H-NMR, HPLC, and AMS datasets show that the composition of the studied SOA systems tend to converge to highly oxidized organic compounds upon prolonged OH exposures. Further, our 1H-NMR findings show that only α-pinene SOA acquires spectroscopic features comparable to those of ambient OA when exposed to at least 1 × 1012 molec OH cm-3 × s OH exposure, or multiple days of equivalent atmospheric OH oxidation. Over multiple days of equivalent OH exposure, the formation of HULIS is observed in both α-pinene SOA and in naphthalene SOA (maximum yields: 16 and 30 %, respectively, of total analyzed water-soluble organic carbon, WSOC), providing evidence of the formation of humic-like polycarboxylic acids in unseeded SOA.

Fast Airborne Aerosol Size and Chemistry Measurements with the High Resolution Aerosol Mass Spectrometer during the MILAGRO Campaign

NASA Technical Reports Server (NTRS)

DeCarlo, P. F.; Dunlea, E. J.; Kimmel, J. R.; Aiken, A. C.; Sueper, D.; Crounse, J.; Wennberg, P. O.; Emmons, L.; Shinozuka, Y.; Clarke, A.;

Seasonal differences in aerosol water may reconcile AOT and surface mass measurements in the Southeast U.S.

NASA Astrophysics Data System (ADS)

Nguyen, T. K. V.; Ghate, V. P.; Carlton, A. M. G.

2015-12-01

Summertime aerosol optical thickness (AOT) in the Southeast U.S. is high and sharply enhanced (2-3 times) compared to wintertime AOT. This seasonal pattern is unique to the Southeast U.S. and is of particular interest because temperatures there have not warmed over the past 100 years, contrasting with trends in other U.S. regions. Some investigators hypothesize the Southeast temperature trend is due to secondary organic aerosols (SOA) formed from interactions of biogenic volatile organic compounds (BVOCs) and anthropogenic emissions that create a cooling haze. However, aerosol measurements made at the surface do not exhibit strong seasonal differences in mass or organic fraction to support this hypothesis. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with surface mass measurements by examining trends in particle-phase liquid water, an aerosol constituent that effectively scatters radiation and is removed from aerosols in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIA (v2.1) to estimate surface and aloft aerosol water mass concentrations at locations of Interagency Monitoring of Protected Visual Environments (IMPROVE) sites using measured speciated ion mass concentrations and NCEP North American Regional Reanalysis (NARR) meteorological data. Results demonstrate strong seasonal differences in aerosol water in the eastern compared to the western part of the U.S., consistent with geographic patterns in AOT. The highest mean regional seasonal difference from 2000 to 2007 is 5.5 μg m-3 and occurs the Southeast, while the lowest is 0.44 μg m-3 and occurs in the dry Mountain West. Our findings suggest 1) similarity between spatial trends in aerosol water in the U.S. and previously published AOT data from the MODIS-TERRA instrument and 2) similar interannual trends in mean aerosol water and previously published interannual AOT trends from MISR, MODIS-TERRA, MODIS

Aqueous-phase photooxidation of levoglucosan - a mechanistic study using aerosol time-of-flight chemical ionization mass spectrometry (Aerosol ToF-CIMS)

NASA Astrophysics Data System (ADS)

Zhao, R.; Mungall, E. L.; Lee, A. K. Y.; Aljawhary, D.; Abbatt, J. P. D.

2014-09-01

Levoglucosan (LG) is a widely employed tracer for biomass burning (BB). Recent studies have shown that LG can react rapidly with hydroxyl (OH) radicals in the aqueous phase despite many mass balance receptor models assuming it to be inert during atmospheric transport. In the current study, aqueous-phase photooxidation of LG by OH radicals was performed in the laboratory. The reaction kinetics and products were monitored by aerosol time-of-flight chemical ionization mass spectrometry (Aerosol ToF-CIMS). Approximately 50 reaction products were detected by the Aerosol ToF-CIMS during the photooxidation experiments, representing one of the most detailed product studies yet performed. By following the evolution of mass defects of product peaks, unique trends of adding oxygen (+O) and removing hydrogen (-2H) were observed among the products detected, providing useful information for determining potential reaction mechanisms and sequences. Additionally, bond-scission reactions take place, leading to reaction intermediates with lower carbon numbers. We introduce a data analysis framework where the average oxidation state (OSc) is plotted against a novel molecular property: double-bond-equivalence-to-carbon ratio (DBE/#C). The trajectory of LG photooxidation on this plot suggests formation of polycarbonyl intermediates and their subsequent conversion to carboxylic acids as a general reaction trend. We also determined the rate constant of LG with OH radicals at room temperature to be 1.08 ± 0.16 × 109 M-1 s-1. By coupling an aerosol mass spectrometer (AMS) to the system, we observed a rapid decay of the mass fraction of organic signals at mass-to-charge ratio 60 (f60), corresponding closely to the LG decay monitored by the Aerosol ToF-CIMS. The trajectory of LG photooxidation on a f44-f60 correlation plot matched closely to literature field measurement data. This implies that aqueous-phase photooxidation might be partially contributing to aging of BB particles in the

Augmenting the spectral efficiency of enhanced PAM-DMT-based optical wireless communications.

PubMed

Islim, Mohamed Sufyan; Haas, Harald

2016-05-30

The energy efficiency of pulse-amplitude-modulated discrete multitone modulation (PAM-DMT) decreases as the modulation order of M-PAM modulation increases. Enhanced PAM-DMT (ePAM-DMT) was proposed as a solution to the reduced energy efficiency of PAM-DMT. This was achieved by allowing multiple streams of PAM-DMT to be superimposed and successively demodulated at the receiver side. In order to maintain a distortion-free unipolar ePAM-DMT system, the multiple time-domain PAM-DMT streams are required to be aligned. However, aligning the antisymmetry in ePAM-DMT is complex and results in efficiency losses. In this paper, a novel simplified method to apply the superposition modulation on M-PAM modulated discrete multitone (DMT) is introduced. Contrary to ePAM-DMT, the signal generation of the proposed system, termed augmented spectral efficiency discrete multitone (ASE-DMT), occurs in the frequency domain. This results in an improved spectral and energy efficiency. The analytical bit error rate (BER) performance bound of the proposed system is derived and compared with Monte-Carlo simulations. The system performance is shown to offer significant electrical and optical energy savings compared with ePAM-DMT and DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM).

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

PubMed Central

Ku, Bon Ki; Evans, Douglas E.

2015-01-01

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

Laboratory and field measurements of organic aerosols with the photoionization aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Dreyfus, Matthew A.

Analytical methods developed to sample and characterize ambient organic aerosols often face the trade-off between long sampling times and the loss of detailed information regarding specific chemical species present. The soft, universal ionization scheme of the Photoionization Aerosol Mass Spectrometer (PIAMS) allows for identification of various chemical compounds by a signature ion, often the molecular ion. The goal of this thesis work is to apply PIAMS to both laboratory and field experiments to answer questions regarding the formation, composition, and behavior of organic aerosols. To achieve this goal, a variety of hardware and software upgrades were administered to PIAMS to optimize the instrument. Data collection and processing software were either refined or built from the ground up to simplify difficult or monotonous tasks. Additional components were added to PIAMS with the intent to automate the instrument, enhance the results, and make the instrument more rugged and user-friendly. These changes, combined with the application of an external particle concentration system (mini-Versatile Aerosol Concentration Enrichment System, m-VACES), allowed PIAMS to be suitable for field measurements of organic aerosols. Two such field campaigns were completed, both at the State of Delaware Air Quality Monitoring Site in Wilmington, Delaware: a one week period in June, 2006, and an 18 day period in October and November of 2007. A sampling method developed was capable of collecting sufficient ambient organic aerosol and analyzing it with a time resolution of 3.5 minutes. Because of this method, short term concentration changes of individual species can be tracked. Combined with meteorological data, the behavior of these species can be analyzed as a function of time or wind direction. Many compounds are found at enhanced levels during the evening/night-time hours; potentially due to the combined effects of temperature inversion, and fresh emissions in a cooler environment

Blood-brain barrier penetration of novel pyridinealdoxime methiodide (PAM)-type oximes examined by brain microdialysis with LC-MS/MS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okuno, Sou; Sakurada, Koichi; Ohta, Hikoto

2008-02-15

To develop a new reactivator of inhibited acetylcholinesterase (AChE) that can easily penetrate the blood-brain barrier (BBB), BBB penetration of 6 known and novel pyridinealdoxime methiodide (PAM)-type oximes (alkylPAMs) with relatively high reactivation activities was examined by in vivo rat brain microdialysis with liquid chromatography-mass spectrometry (LC-MS/MS). The 50% lethal dose (LD{sub 50}) of alkylPAMs was intravenously determined for Wistar rats, then the limit of detection, quantification range and linearity of the calibration curve of the alkylPAMs in dialysate and blood were determined by LC-MS/MS. Following 10% LD{sub 50} intravenous administration of the alkylPAMs, 4-[(hydroxyimino) methyl]-1-(2-phenylethyl) pyridinium bromide (4-PAPE) andmore » 4-[(hydroxyimino) methyl]-1-octylpyridinium bromide (4-PAO) appeared in the dialysate. Striatal extracellular fluid/blood concentration ratios were 0.039 {+-} 0.018 and 0.301 {+-} 0.183 (mean {+-} SEM), respectively, 1 h after treatment. This is the first report of BBB penetration of 4-PAPE, and the concentration ratio was smaller than that of 2-PAM.The mean BBB penetration of 4-PAO was approximately 30%, indicating that intravenous administration of 4-PAO may be effective for the reactivation of blocked cholinesterase in the brain. However, the toxicity of 4-PAO (LD{sub 50}; 8.89 mg/kg) was greater than that of 2-PAM. Further investigation is required to determine the effects of these alkylPAMs in organophosphate poisoning.« less

Mass spectrometric airborne measurements of submicron aerosol and cloud residual composition in tropic deep convection during ACRIDICON-CHUVA

NASA Astrophysics Data System (ADS)

Schulz, Christiane; Schneider, Johannes; Mertes, Stephan; Kästner, Udo; Weinzierl, Bernadett; Sauer, Daniel; Fütterer, Daniel; Walser, Adrian; Borrmann, Stephan

2015-04-01

Airborne measurements of submicron aerosol and cloud particles were conducted in the region of Manaus (Amazonas, Brazil) during the ACRIDICON-CHUVA campaign in September 2014. ACRIDICON-CHUVA aimed at the investigation of convective cloud systems in order to get a better understanding and quantification of aerosol-cloud-interactions and radiative effects of convective clouds. For that, data from airborne measurements within convective cloud systems are combined with satellite and ground-based data. We used a C-ToF-AMS (Compact-Time-of-Flight-Aerosol-Mass-Spectrometer) to obtain information on aerosol composition and vertical profiles of different aerosol species, like organics, sulphate, nitrate, ammonium and chloride. The instrument was operated behind two different inlets: The HASI (HALO Aerosol Submicrometer Inlet) samples aerosol particles, whereas the CVI (Counterflow Virtual Impactor) samples cloud droplets and ice particles during in-cloud measurements, such that cloud residual particles can be analyzed. Differences in aerosol composition inside and outside of clouds and cloud properties over forested or deforested region were investigated. Additionally, the in- and outflow of convective clouds was sampled on dedicated cloud missions in order to study the evolution of the clouds and the processing of aerosol particles. First results show high organic aerosol mass concentrations (typically 15 μg/m3 and during one flight up to 25 μg/m3). Although high amounts of organic aerosol in tropic air over rainforest regions were expected, such high mass concentrations were not anticipated. Next to that, high sulphate aerosol mass concentrations (about 4 μg/m3) were measured at low altitudes (up to 5 km). During some flights organic and nitrate aerosol was observed with higher mass concentrations at high altitudes (10-12 km) than at lower altitudes, indicating redistribution of boundary layer particles by convection. The cloud residuals measured during in

Latitudinal distribution of aerosol black carbon and its mass fraction to composite aerosols over peninsular India during winter season

NASA Astrophysics Data System (ADS)

Moorthy, K. Krishna; Babu, S. Suresh; Badarinath, K. V. S.; Sunilkumar, S. V.; Kiranchand, T. R.; Ahmed, Y. Nazeer

2007-04-01

During a land campaign to characterise the spatial distribution of aerosols over peninsular India during the winter season, extensive, collocated, and spatially resolved measurements of mass concentration of the composite aerosols (MT) as well as that (MB) of aerosol Black Carbon (BC) were made over different environments (coastal, industrial, urban, village, remote, semiarid) of the western peninsular India. High concentrations of BC, >2.5 μg m-3, were observed along the west coast, from ~8°N up to 14.5°N, and moderate values (1.0 to 2.5 μg m-3) over inland regions from 15 to 18°N. Latitudinally, BC concentration decreased from south to north, @~160 ng m-3 for every degree increase in latitude. The spatial pattern of BC mass fraction differed from that of MB, with regions of high (8 to 16%) ratios spreading more interior, implying higher fractional load of BC at locations where the BC concentrations remain lower.

Sources and atmospheric processing of winter aerosols in Seoul, Korea: insights from real-time measurements using a high-resolution aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Kim, Hwajin; Zhang, Qi; Bae, Gwi-Nam; Kim, Jin Young; Bok Lee, Seung

2017-02-01

Highly time-resolved chemical characterization of nonrefractory submicrometer particulate matter (NR-PM1) was conducted in Seoul, the capital and largest metropolis of Korea, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The measurements were performed during winter, when elevated particulate matter (PM) pollution events are often observed. This is the first time that detailed real-time aerosol measurement results have been reported from Seoul, Korea, and they reveal valuable insights into the sources and atmospheric processes that contribute to PM pollution in this region. The average concentration of submicron aerosol (PM1 = NR-PM1+ black carbon (BC)) was 27.5 µg m-3, and the total mass was dominated by organics (44 %), followed by nitrate (24 %) and sulfate (10 %). The average atomic ratios of oxygen to carbon (O / C), hydrogen to carbon (H / C), and nitrogen to carbon (N / C) of organic aerosols (OA) were 0.37, 1.79, and 0.018, respectively, which result in an average organic mass-to-carbon (OM / OC) ratio of 1.67. The concentrations (2.6-90.7 µg m-3) and composition of PM1 varied dynamically during the measurement period due to the influences of different meteorological conditions, emission sources, and air mass origins. Five distinct sources of OA were identified via positive matrix factorization (PMF) analysis of the HR-ToF-AMS data: vehicle emissions represented by a hydrocarbon-like OA factor (HOA, O / C = 0.06), cooking activities represented by a cooking OA factor (COA, O / C = 0.14), wood combustion represented by a biomass burning OA factor (BBOA, O / C = 0.34), and secondary organic aerosol (SOA) represented by a semivolatile oxygenated OA factor (SV-OOA, O / C = 0.56) and a low-volatility oxygenated OA factor (LV-OOA, O / C = 0.68). On average, primary OA (POA = HOA + COA + BBOA) accounted for 59 % the OA mass, whereas SV-OOA and LV-OOA contributed 15 and 26 %, respectively. Our results indicate that air

Black carbon aerosol mixing state, organic aerosols and aerosol optical properties over the UK

NASA Astrophysics Data System (ADS)

McMeeking, G. R.; Morgan, W. T.; Flynn, M.; Highwood, E. J.; Turnbull, K.; Haywood, J.; Coe, H.

2011-05-01

Black carbon (BC) aerosols absorb sunlight thereby leading to a positive radiative forcing and a warming of climate and can also impact human health through their impact on the respiratory system. The state of mixing of BC with other aerosol species, particularly the degree of internal/external mixing, has been highlighted as a major uncertainty in assessing its radiative forcing and hence its climate impact, but few in situ observations of mixing state exist. We present airborne single particle soot photometer (SP2) measurements of refractory BC (rBC) mass concentrations and mixing state coupled with aerosol composition and optical properties measured in urban plumes and regional pollution over the UK. All data were obtained using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM). We measured sub-micron aerosol composition using an aerosol mass spectrometer (AMS) and used positive matrix factorization to separate hydrocarbon-like (HOA) and oxygenated organic aerosols (OOA). We found a higher number fraction of thickly coated rBC particles in air masses with large OOA relative to HOA, higher ozone-to-nitrogen oxides (NOx) ratios and large concentrations of total sub-micron aerosol mass relative to rBC mass concentrations. The more ozone- and OOA-rich air masses were associated with transport from continental Europe, while plumes from UK cities had higher HOA and NOx and fewer thickly coated rBC particles. We did not observe any significant change in the rBC mass absorption efficiency calculated from rBC mass and light absorption coefficients measured by a particle soot absorption photometer despite observing significant changes in aerosol composition and rBC mixing state. The contributions of light scattering and absorption to total extinction (quantified by the single scattering albedo; SSA) did change for different air masses, with lower SSA observed in

Urban organic aerosols measured by single particle mass spectrometry in the megacity of London

NASA Astrophysics Data System (ADS)

Dall'Osto, M.; Harrison, R. M.

2011-02-01

During the month of October 2006, as part of the REPARTEE-I experiment (Regent's Park and Tower Environmental Experiment) an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed at an urban background location in the city of London, UK. Fifteen particle types were classified, some of which were accompanied by Aerosol Mass Spectrometer (AMS) quantitative aerosol mass loading measurements (Dall'Osto et al., 2009a, b). In this manuscript the origins and properties of four particle types associated with locally generated aerosols, independent of the air mass type advected into London, are examined. One particle type, originating from lubricating oil (referred to as Ca-EC), was associated with morning rush hour traffic emissions. A second particle type, composed of both inorganic and organic species (called Na-EC-OC), was found enhanced in particle number concentration during evening time periods, and is likely to originate from a source operating at this time of day, or more probably from condensation of semi-volatile species, and contains both primary and secondary components. A third class, internally mixed with organic carbon and sulphate (called OC), was found to spike both in the morning and evenings. The fourth class (SOA-PAH) exhibited maximum frequency during the warmest part of the day, and a number of factors point towards secondary production from traffic-related volatile aromatic compounds. Single particle mass spectra of this particle type showed an oxidized polycyclic aromatic compound signature. Finally, a comparison of ATOFMS particle class data is made with factors obtained by Positive Matrix Factorization from AMS data.. Both the Ca-EC and OC particle types correlate with the AMS HOA primary organic fraction (R2 = 0.65 and 0.50 respectively), and Na-EC-OC, but not SOA-PAH, which correlates weakly with the AMS OOA secondary organic aerosol factor (R2 = 0.35). A detailed analysis was conducted to identify ATOFMS particle type(s) representative

Tropical cyclone Pam field survey in Vanuatu

NASA Astrophysics Data System (ADS)

Fritz, Hermann M.; Pilarczyk, Jessica E.; Kosciuch, Thomas; Hong, Isabel; Rarai, Allan; Harrison, Morris J.; Jockley, Fred R.; Horton, Benjamin P.

2016-04-01

Severe tropical cyclone Pam (Cat. 5, SSHS) crossed the Vanuatu archipelago with sustained winds of 270 km/h on March 13 and 14, 2015 and made landfall on Erromango. Pam is the most intense tropical cyclone to make landfall on Vanuatu since the advent of satellite imagery based intensity estimates in the 1970s. Pam caused one of the worst natural disaster in Vanuatu's recorded history. Eleven fatalities were directly attributed to cyclone Pam and mostly due to lack of shelter from airborne debris. On March 6 Pam formed east of the Santa Cruz Islands causing coastal inundation on Tuvalu's Vaitupu Island located some 1100 km east of the cyclone center. Pam intensified while tracking southward along Vanuatu severely affecting the Shefa and Tafea Provinces. An international storm surge reconnaissance team was deployed to Vanuatu from June 3 to 17, 2015 to complement earlier local surveys. Cyclone Pam struck a remote island archipelago particularly vulnerable to the combined cyclonic multi-hazards encompassing extreme wind gusts, massive rainfall and coastal flooding due to a combination of storm surge and storm wave impacts. The team surveyed coastal villages on Epi, the Shepherd Islands (Tongoa and Mataso), Efate (including Lelepa), Erromango, and Tanna. The survey spanned 320 km parallel to the cyclone track between Epi and Tanna encompassing more than 45 sites including the hardest hit settlements. Coastal flooding profiles were surveyed from the shoreline to the limit of inundation. Maximum coastal flood elevations and overland flow depths were measured based on water marks on buildings, scars on trees, rafted debris and corroborated with eyewitness accounts. We surveyed 91 high water marks with characteristic coastal flood levels in the 3 to 7 m range and composed of storm surge with superimposed storm waves. Inundation distances were mostly limited to a few hundred meters but reached 800 m on Epi Island. Wrack lines containing pumice perfectly delineated the

CYP51 is an essential drug target for the treatment of primary amoebic meningoencephalitis (PAM)

PubMed Central

Debnath, Anjan; Calvet, Claudia M.; Aksenov, Alexander; Abagyan, Ruben; Nes, W. David; McKerrow, James H.

2017-01-01

Primary Amoebic Meningoencephalitis (PAM) is caused by Naegleria fowleri, a free-living amoeba that occasionally infects humans. While considered “rare” (but likely underreported) the high mortality rate and lack of established success in treatment makes PAM a particularly devastating infection. In the absence of economic inducements to invest in development of anti-PAM drugs by the pharmaceutical industry, anti-PAM drug discovery largely relies on drug ‘repurposing’—a cost effective strategy to apply known drugs for treatment of rare or neglected diseases. Similar to fungi, N. fowleri has an essential requirement for ergosterol, a building block of plasma and cell membranes. Disruption of sterol biosynthesis by small-molecule inhibitors is a validated interventional strategy against fungal pathogens of medical and agricultural importance. The N. fowleri genome encodes the sterol 14-demethylase (CYP51) target sharing ~35% sequence identity to fungal orthologues. The similarity of targets raises the possibility of repurposing anti-mycotic drugs and optimization of their usage for the treatment of PAM. In this work, we (i) systematically assessed the impact of anti-fungal azole drugs, known as conazoles, on sterol biosynthesis and viability of cultured N. fowleri trophozotes, (ii) identified the endogenous CYP51 substrate by mass spectrometry analysis of N. fowleri lipids, and (iii) analyzed the interactions between the recombinant CYP51 target and conazoles by UV-vis spectroscopy and x-ray crystallography. Collectively, the target-based and parasite-based data obtained in these studies validated CYP51 as a potentially ‘druggable’ target in N. fowleri, and conazole drugs as the candidates for assessment in the animal model of PAM. PMID:29284029

Long-range transport biomass burning emissions to the Himalayas: insights from high-resolution aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Xu, J.; Zhang, X.; Liu, Y.; Shichang, K.; Ma, Y.

2017-12-01

An intensive measurement was conducted at a remote, background, and high-altitude site (Qomolangma station, QOMS, 4276 m a.s.l.) in the northern Himalayas, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) along with other collocated instruments. The field measurement was performed from April 12 to May 12, 2016 to chemically characterize high time-resolved submicron particulate matter (PM1) and obtain the influence of biomass burning emissions to the Himalayas, frequently transported from south Asia during pre-monsoon season. Two high aerosol loading periods were observed during the study. Overall, the average (± 1σ) PM1 mass concentration was 4.44 (± 4.54) µg m-3 for the entire study, comparable with those observed at other remote sites worldwide. Organic aerosols (OA) was the dominant PM1 species (accounting for 54.3% of total PM1 mass on average) and its contribution increased with the increase of total PM1 mass loading. The average size distributions of PM1 species all peaked at an overlapping accumulation mode ( 500 nm), suggesting that aerosol particles were internally well-mixed and aged during long-range transportations. Positive matrix factorization (PMF) analysis on the high-resolution organic mass spectra identified three distinct OA factors, including a biomass burning related OA (BBOA, 43.7%) and two oxygenated OA (Local-OOA and LRT-OOA; 13.9% and 42.4%) represented sources from local emissions and long-range transportations, respectively. Two polluted air mass origins (generally from the west and southwest of QOMS) and two polluted episodes with enhanced PM1 mass loadings and elevated BBOA contributions were observed, respectively, suggesting the important sources of wildfires from south Asia. One of polluted aerosol plumes was investigated in detail to illustrate the evolution of aerosol characteristics at QOMS driving by different impacts of wildfires, air mass origins, meteorological conditions and

Engineered Cpf1 variants with altered PAM specificities.

PubMed

Gao, Linyi; Cox, David B T; Yan, Winston X; Manteiga, John C; Schneider, Martin W; Yamano, Takashi; Nishimasu, Hiroshi; Nureki, Osamu; Crosetto, Nicola; Zhang, Feng

2017-08-01

The RNA-guided endonuclease Cpf1 is a promising tool for genome editing in eukaryotic cells. However, the utility of the commonly used Acidaminococcus sp. BV3L6 Cpf1 (AsCpf1) and Lachnospiraceae bacterium ND2006 Cpf1 (LbCpf1) is limited by their requirement of a TTTV protospacer adjacent motif (PAM) in the DNA substrate. To address this limitation, we performed a structure-guided mutagenesis screen to increase the targeting range of Cpf1. We engineered two AsCpf1 variants carrying the mutations S542R/K607R and S542R/K548V/N552R, which recognize TYCV and TATV PAMs, respectively, with enhanced activities in vitro and in human cells. Genome-wide assessment of off-target activity using BLISS indicated that these variants retain high DNA-targeting specificity, which we further improved by introducing an additional non-PAM-interacting mutation. Introducing the identified PAM-interacting mutations at their corresponding positions in LbCpf1 similarly altered its PAM specificity. Together, these variants increase the targeting range of Cpf1 by approximately threefold in human coding sequences to one cleavage site per ∼11 bp.

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

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

DOE PAGES

VanReken, T. M.; Mwaniki, G. R.; Wallace, H. W.; ...

2015-02-10

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

Brown at aft controls during PAMS STU deploy

NASA Image and Video Library

1996-05-22

S77-E-5066 (22 May 1996) --- Astronaut Curtis L. Brown, Jr., pilot, is seen on the starboard side of the Space Shuttle Endeavour's aft flight deck just prior to the deployment of the Satellite Test Unit (STU), part of the Passive Aerodynamically Stabilized Magnetically Damped Satellite (PAMS). Brown's image was captured with an Electronic Still Camera (ESC). Minutes later the camera was being used to document the deployment of PAMS-STU. The six-member crew will continue operations (tracking, rendezvousing and station-keeping) with PAMS-STU periodically throughout the remainder of the mission.

Characterizing source fingerprints and ageing processes in laboratory-generated secondary organic aerosols using proton-nuclear magnetic resonance ( 1H-NMR) analysis and HPLC HULIS determination

DOE PAGES

Zanca, Nicola; Lambe, Andrew T.; Massoli, Paola; ...

2017-09-06

The study of secondary organic aerosol (SOA) in laboratory settings has greatly increased our knowledge of the diverse chemical processes and environmental conditions responsible for the formation of particulate matter starting from biogenic and anthropogenic volatile compounds. However, characteristics of the different experimental setups and the way they impact the composition and the timescale of formation of SOA are still subject to debate. In this study, SOA samples were generated using a potential aerosol mass (PAM) oxidation flow reactor using α-pinene, naphthalene and isoprene as precursors. The PAM reactor facilitated exploration of SOA composition over atmospherically relevant photochemical ageing timescalesmore » that are unattainable in environmental chambers. The SOA samples were analyzed using two state-of-the-art analytical techniques for SOA characterization – proton nuclear magnetic resonance ( 1H-NMR) spectroscopy and HPLC determination of humic-like substances (HULIS). Results were compared with previous Aerodyne aerosol mass spectrometer (AMS) measurements. The combined 1H-NMR, HPLC, and AMS datasets show that the composition of the studied SOA systems tend to converge to highly oxidized organic compounds upon prolonged OH exposures. Further, our 1H-NMR findings show that only α-pinene SOA acquires spectroscopic features comparable to those of ambient OA when exposed to at least 1×10 12 molec OH cm -3 × s OH exposure, or multiple days of equivalent atmospheric OH oxidation. Over multiple days of equivalent OH exposure, the formation of HULIS is observed in both α-pinene SOA and in naphthalene SOA (maximum yields: 16 and 30 %, respectively, of total analyzed water-soluble organic carbon, WSOC), providing evidence of the formation of humic-like polycarboxylic acids in unseeded SOA.« less

Characterizing source fingerprints and ageing processes in laboratory-generated secondary organic aerosols using proton-nuclear magnetic resonance ( 1H-NMR) analysis and HPLC HULIS determination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zanca, Nicola; Lambe, Andrew T.; Massoli, Paola

The study of secondary organic aerosol (SOA) in laboratory settings has greatly increased our knowledge of the diverse chemical processes and environmental conditions responsible for the formation of particulate matter starting from biogenic and anthropogenic volatile compounds. However, characteristics of the different experimental setups and the way they impact the composition and the timescale of formation of SOA are still subject to debate. In this study, SOA samples were generated using a potential aerosol mass (PAM) oxidation flow reactor using α-pinene, naphthalene and isoprene as precursors. The PAM reactor facilitated exploration of SOA composition over atmospherically relevant photochemical ageing timescalesmore » that are unattainable in environmental chambers. The SOA samples were analyzed using two state-of-the-art analytical techniques for SOA characterization – proton nuclear magnetic resonance ( 1H-NMR) spectroscopy and HPLC determination of humic-like substances (HULIS). Results were compared with previous Aerodyne aerosol mass spectrometer (AMS) measurements. The combined 1H-NMR, HPLC, and AMS datasets show that the composition of the studied SOA systems tend to converge to highly oxidized organic compounds upon prolonged OH exposures. Further, our 1H-NMR findings show that only α-pinene SOA acquires spectroscopic features comparable to those of ambient OA when exposed to at least 1×10 12 molec OH cm -3 × s OH exposure, or multiple days of equivalent atmospheric OH oxidation. Over multiple days of equivalent OH exposure, the formation of HULIS is observed in both α-pinene SOA and in naphthalene SOA (maximum yields: 16 and 30 %, respectively, of total analyzed water-soluble organic carbon, WSOC), providing evidence of the formation of humic-like polycarboxylic acids in unseeded SOA.« less

Black carbon aerosol mixing state, organic aerosols and aerosol optical properties over the United Kingdom

NASA Astrophysics Data System (ADS)

McMeeking, G. R.; Morgan, W. T.; Flynn, M.; Highwood, E. J.; Turnbull, K.; Haywood, J.; Coe, H.

2011-09-01

Black carbon (BC) aerosols absorb sunlight thereby leading to a positive radiative forcing and a warming of climate and can also impact human health through their impact on the respiratory system. The state of mixing of BC with other aerosol species, particularly the degree of internal/external mixing, has been highlighted as a major uncertainty in assessing its radiative forcing and hence its climate impact, but few in situ observations of mixing state exist. We present airborne single particle soot photometer (SP2) measurements of refractory BC (rBC) mass concentrations and mixing state coupled with aerosol composition and optical properties measured in urban plumes and regional pollution over the United Kingdom. All data were obtained using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM). We measured sub-micron aerosol composition using an aerosol mass spectrometer (AMS) and used positive matrix factorization to separate hydrocarbon-like (HOA) and oxygenated organic aerosols (OOA). We found a higher number fraction of thickly coated rBC particles in air masses with large OOA relative to HOA, higher ozone-to-nitrogen oxides (NOx) ratios and large concentrations of total sub-micron aerosol mass relative to rBC mass concentrations. The more ozone- and OOA-rich air masses were associated with transport from continental Europe, while plumes from UK cities had higher HOA and NOx and fewer thickly coated rBC particles. We did not observe any significant change in the rBC mass absorption efficiency calculated from rBC mass and light absorption coefficients measured by a particle soot absorption photometer despite observing significant changes in aerosol composition and rBC mixing state. The contributions of light scattering and absorption to total extinction (quantified by the single scattering albedo; SSA) did change for different air masses, with lower SSA

THE MASS ACCOMMODATION COEFFICIENT OF AMMONIUM NITRATE AEROSOL. (R823514)

EPA Science Inventory

The mass transfer rate of pure ammonium nitrate between the aerosol and gas phases was
quantified experimentally by the use of the tandem differential mobility analyzer/scanning mobility
particle sizer (TDMA/SMPS) technique. Ammonium nitrate particles 80-220 nm in diameter<...

Chemical Characterization of Particulate Matter at the La Porte site Using an Aerosol Mass Spectrometer

NASA Astrophysics Data System (ADS)

Silva, P. J.; Worsnop, D.; Canagaratna, M.; Jimenez, J. L.; Delia, A.; Purvis, K.; Davidovits, P.

2001-12-01

During the summer of 2000, a large atmospheric chemistry field campaign took place in the Greater Houston area in conjunction with an EPA supersite. As part of the campaign, we operated an aerosol mass spectrometer from 20 August, 2000 until 15 September, 2000. The aerosol mass spectrometer (AMS) obtained chemical composition data and particle size distributions continuously with 10 minute averaging times. The measured aerosol mass concentration ranged from approximately 2 μ g m-3 to a high of 30 μ g m-3. Ammonium and sulfate were the two dominant chemical species present during most of the study. The mass concentration of particulate nitrate was typically less than a few μ g m-3, with one major nitrate event on 23 August, 2000. Very small amounts of non-sea salt chloride were detected in the particles, typically less than one μ g m-3, again with the largest value detected on 23 August 2000. In addition to the inorganic species, several different organic aerosol types were identified based on simple evaluation of mass spectral and size distribution data. Three organic particle types appear to be from discrete primary sources of organic aerosol. A combustion particle type displays mass spectra similar to those observed from diesel exhaust emissions. The temporal variation of this type shows sharp spikes, consistent with primary sources and sharp plumes that drift pass. A second organic particle type is responsible for the largest particle mass concentrations observed during the entire study, occurring during a fire episode on 5-6 September, 2000. The mass spectra exhibit characteristic peaks representative of markers for compounds from biomass burning, including levoglucosan and dehydroabietic acid. A third organic particle type observed during the study exhibits peaks in the mass spectra that are characteristic of fluorinated hydrocarbons and are similar to mass spectra of pump oil. This particle type contributes several μ g m-3 to the ambient particle mass

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

NASA Astrophysics Data System (ADS)

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

2015-10-01

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

Bio-Aerosol Detection Using Mass Spectrometry: Public Health Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ludvigson, Laura D.

2004-01-01

I recently spent a summer as an intern at the Lawrence Livermore National Laboratory. I worked on a project involving the real-time, reagentless, single cell detection of aerosolized pathogens using a novel mass spectrometry approach called Bio-Aerosol Mass Spectrometry (BAMS). Based upon preliminary results showing the differentiation capabilities of BAMS, I would like to explore the development and use of this novel detection system in the context of both environmental and clinical sample pathogen detection. I would also like to explore the broader public health applications that a system such as BAMS might have in terms of infectious disease preventionmore » and control. In order to appreciate the potential of this instrument, I will demonstrate the need for better pathogen detection methods, and outline the instrumentation, data analysis and preliminary results that lead me toward a desire to explore this technology further. I will also discuss potential experiments for the future along with possible problems that may be encountered along the way.« less

Power budget enhancement in NG-EPON system employing novel twisted-PAM4

NASA Astrophysics Data System (ADS)

Li, Longsheng; Bi, Meihua; Fu, Yan; Miao, Xin; Zhu, Qingming; Hu, Weisheng

2018-03-01

In this paper, we firstly design a novel modulation format named Twisted-PAM4 (T-PAM4) for the high-speed NG-EPON and the PON-based digital fronthaul system. Compared to other high-order modulation formats like 4-ary pulse amplitude modulation (PAM4), T-PAM4 provides two independent sampling values in each symbol period and enables two-dimensional symbol decision, which significantly improves the receiver sensitivity and hence enlarges the system power budget. Based on this advantage, six types of T-PAM4 are experimentally demonstrated in 28-Gb/s/ λ NG-PON and 32-Gb/s/ λ PON-based digital fronthaul system. The experimental results show that, compared to the ordinary PAM4, the T-PAM4 can bring 5-dB and 4-dB extra power budget in NG-EPON and PON-based fronthaul system respectively. In addition, by experiment, it is also depicted that the T-PAM4 is remarkably robust to system nonlinearity, which would ease the linearity requirement on system components and hence reduce system cost.

A New Method Using Single-Particle Mass Spectrometry Data to Distinguish Mineral Dust and Biological Aerosols

NASA Astrophysics Data System (ADS)

Al-Mashat, H.; Kristensen, L.; Sultana, C. M.; Prather, K. A.

2016-12-01

The ability to distinguish types of particles present within a cloud is important for determining accurate inputs to climate models. The chemical composition of particles within cloud liquid droplets and ice crystals can have a significant impact on the timing, location, and amount of precipitation that falls. Precipitation efficiency is increased by the presence of ice crystals in clouds, and both mineral dust and biological aerosols have been shown to be effective ice nucleating particles (INPs) in the atmosphere. A current challenge in aerosol science is distinguishing mineral dust and biological material in the analysis of real-time, ambient, single-particle mass spectral data. Single-particle mass spectrometers are capable of measuring the size-resolved chemical composition of individual atmospheric particles. However, there is no consistent analytical method for distinguishing dust and biological aerosols. Sampling and characterization of control samples (i.e. of known identity) of mineral dust and bacteria were performed by the Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) as part of the Fifth Ice Nucleation (FIN01) Workshop at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) facility in Karlsruhe, Germany. Using data collected by the ATOFMS of control samples, a new metric has been developed to classify single particles as dust or biological independent of spectral cluster analysis. This method, involving the use of a ratio of mass spectral peak areas for organic nitrogen and silicates, is easily reproducible and does not rely on extensive knowledge of particle chemistry or the ionization characteristics of mass spectrometers. This represents a step toward rapidly distinguishing particle types responsible for ice nucleation activity during real-time sampling in clouds. The ability to distinguish types of particles present within a cloud is important for determining accurate inputs to climate models. The chemical composition of particles

Ambient Aerosol in Southeast Asia: High Resolution Aerosol Mass Spectrometer Measurements Over Oil Palm (Elaeis guineensis)

NASA Astrophysics Data System (ADS)

Phillips, G.; Dimarco, C.; Misztal, P.; Nemitz, E.; Farmer, D.; Kimmel, J.; Jimenez, J.

2008-12-01

The emission of organic compounds in the troposphere is important factor in the formation of secondary organic aerosol (SOA). A very large proportion of organic material emitted globally is estimated to arise from biogenic sources, with almost half coming from tropical and sub-tropical forests. Preliminary analyses of leave cuvette emission studies suggest that oil palm (Elaeis guineensis) is a significantly larger source of isoprene than tropical forest. Much larger sources of isoprene over oil palm allied with a larger anthropogenic component of local emissions contrast greatly with the remote tropical forest environment and therefore the character of SOA formed may differ significantly. These issues, allied with the high price of palm oil on international markets leading to increased use of land for oil palm production, could give rise to rapidly changing chemical and aerosol regimes in the tropics. It is therefore important to understand the current emissions and composition of organic aerosol over all important land-uses in the tropical environment. This in turn will lead to a greater understanding of the present, and to an improvement in predictive capacity for the future system. To help address these issues, a high resolution time of flight aerosol mass spectrometer (HR-ToF-AMS) was deployed in the Sabahmas (PPB OIL) oil palm plantation near Lahad Datu, in Eastern Sabah, as part of the field component of the Aerosol Coupling in the Earth System (ACES) project, part of the UK NERC APPRAISE program. This project was allied closely with measurements made of similar chemical species and aerosol components at a forest site in the Danum Valley as part of the UK Oxidant and Particle Photochemical Processes above a Southeast Asian tropical rainforest (OP3) project. Measurements of submicron non- refractory aerosol composition are presented along with some preliminary analysis of chemically resolved aerosol fluxes made with a new eddy covariance system, based on the

Expanding Single Particle Mass Spectrometer Analyses for the Identification of Microbe Signatures in Sea Spray Aerosol.

PubMed

Sultana, Camille M; Al-Mashat, Hashim; Prather, Kimberly A

2017-10-03

Ocean-derived microbes in sea spray aersosol (SSA) have the potential to influence climate and weather by acting as ice nucleating particles in clouds. Single particle mass spectrometers (SPMSs), which generate in situ single particle composition data, are excellent tools for characterizing aerosols under changing environmental conditions as they can provide high temporal resolution and require no sample preparation. While SPMSs have proven capable of detecting microbes, these instruments have never been utilized to definitively identify aerosolized microbes in ambient sea spray aersosol. In this study, an aerosol time-of-flight mass spectrometer was used to analyze laboratory generated SSA produced from natural seawater in a marine aerosol reference tank. We present the first description of a population of biological SSA mass spectra (BioSS), which closely match the ion signatures observed in previous terrestrial microbe studies. The fraction of BioSS dramatically increased in the largest supermicron particles, consistent with field and laboratory measurements of microbes ejected by bubble bursting, further supporting the assignment of BioSS mass spectra as microbes. Finally, as supported by analysis of inorganic ion signals, we propose that dry BioSS particles have heterogeneous structures, with microbes adhered to sodium chloride nodules surrounded by magnesium-enriched coatings. Consistent with this structure, chlorine-containing ion markers were ubiquitous in BioSS spectra and identified as possible tracers for distinguishing recently aerosolized marine from terrestrial microbes.

Urban organic aerosols measured by single particle mass spectrometry in the megacity of London

NASA Astrophysics Data System (ADS)

Dall'Osto, M.; Harrison, R. M.

2012-05-01

During the month of October 2006, as part of the REPARTEE-I experiment (Regent's Park and Tower Environmental Experiment) an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed at an urban background location in the city of London, UK. Fifteen particle types were classified, some of which were already discussed (Dall'Osto et al., 2009a,b; Harrison et al., 2012). In this manuscript the origins and properties of four unreported particle types postulated to be due to locally generated aerosols, independent of the air mass type advected into London, are examined. One particle type, originating from lubricating oil (referred to as Ca-EC), was associated with morning rush hour traffic emissions. A second particle type, composed of both inorganic and organic species (called Na-EC-OC), was found enhanced in particle number concentration during evening time periods, and is likely to originate from a source operating at this time of day, or more probably from condensation of semi-volatile species. A third class, internally mixed with organic carbon and sulphate (called OC), was found to spike both in the morning and evenings although it could not unambiguously associated with a specific source or atmospheric process. The fourth class (Secondary Organic Aerosols - Polycyclic Aromatic Hydrocarbon; SOA-PAH) exhibited maximum frequency during the warmest part of the day, and a number of factors point towards secondary aerosol production from traffic-related volatile aromatic compounds. Single particle mass spectra of this particle type showed an oxidized polycyclic aromatic compound signature. A comparison of ATOFMS particle class data is then made with factors obtained by Positive Matrix Factorization and PAH signatures obtained from Aerosol Mass Spectrometer (AMS) data (Allan et al., 2010). Both the Ca-EC and OC particle types correlate with primary Hydrocarbon-like Organic Aerosol (HOA, R2 = 0.65 and 0.50 respectively), and Na-EC-OC correlates weakly with the AMS

Evaluation of Aerosol Mixing State Classes in the GISS Modele-matrix Climate Model Using Single-particle Mass Spectrometry Measurements

NASA Technical Reports Server (NTRS)

Bauer, Susanne E.; Ault, Andrew; Prather, Kimberly A.

2013-01-01

Aerosol particles in the atmosphere are composed of multiple chemical species. The aerosol mixing state, which describes how chemical species are mixed at the single-particle level, provides critical information on microphysical characteristics that determine the interaction of aerosols with the climate system. The evaluation of mixing state has become the next challenge. This study uses aerosol time-of-flight mass spectrometry (ATOFMS) data and compares the results to those of the Goddard Institute for Space Studies modelE-MATRIX (Multiconfiguration Aerosol TRacker of mIXing state) model, a global climate model that includes a detailed aerosol microphysical scheme. We use data from field campaigns that examine a variety of air mass regimens (urban, rural, and maritime). At all locations, polluted areas in California (Riverside, La Jolla, and Long Beach), a remote location in the Sierra Nevada Mountains (Sugar Pine) and observations from Jeju (South Korea), the majority of aerosol species are internally mixed. Coarse aerosol particles, those above 1 micron, are typically aged, such as coated dust or reacted sea-salt particles. Particles below 1 micron contain large fractions of organic material, internally-mixed with sulfate and black carbon, and few external mixtures. We conclude that observations taken over multiple weeks characterize typical air mass types at a given location well; however, due to the instrumentation, we could not evaluate mass budgets. These results represent the first detailed comparison of single-particle mixing states in a global climate model with real-time single-particle mass spectrometry data, an important step in improving the representation of mixing state in global climate models.

Differentiation of pancreatic ductal adenocarcinoma from chronic pancreatitis by PAM4 immunohistochemistry.

PubMed

Shi, Chanjuan; Merchant, Nipun; Newsome, Guy; Goldenberg, David M; Gold, David V

2014-02-01

PAM4 is a monoclonal antibody that shows high specificity for pancreatic ductal adenocarcinoma (PDAC) and its neoplastic precursor lesions. A PAM4-based serum immunoassay is able to detect 71% of early-stage patients and 91% with advanced disease. However, approximately 20% of patients diagnosed with chronic pancreatitis (CP) are also positive for circulating PAM4 antigen. The specificity of the PAM4 antibody is critical to the interpretation of the serum-based and immunohistochemical assays for detection of PDAC. To determine whether PAM4 can differentiate PDAC from nonneoplastic lesions of the pancreas. Tissue microarrays of PDAC (N = 43) and surgical specimens from CP (N = 32) and benign cystic lesions (N = 19) were evaluated for expression of the PAM4 biomarker, MUC1, MUC4, CEACAM5/6, and CA19-9. PAM4 and monoclonal antibodies (MAbs) to MUC1, MUC4, CEACAM5/6, and CA19-9 were each reactive with the majority of PDAC cases; however, PAM4 was the only monoclonal antibody not to react with adjacent, nonneoplastic parenchyma. Although PAM4 labeled 19% (6 of 32) of CP specimens, reactivity was restricted to pancreatic intraepithelial neoplasia associated with CP; inflamed tissues were negative in all cases. In contrast, MUC1, MUC4, CEACAM5/6, and CA19-9 were detected in 90%, 78%, 97%, and 100% of CP, respectively, with reactivity also present in nonneoplastic inflamed tissue. PAM4 was the only monoclonal antibody able to differentiate PDAC (and pancreatic intraepithelial neoplasia precursor lesions) from benign, nonneoplastic tissues of the pancreas. These results suggest the use of PAM4 for evaluation of tissue specimens, and support its role as an immunoassay for detection of PDAC.

Characterization of submicron aerosols at a rural site in Pearl River Delta of China using an Aerodyne High-Resolution Aerosol Mass Spectrometer

NASA Astrophysics Data System (ADS)

Huang, X.-F.; He, L.-Y.; Hu, M.; Canagaratna, M. R.; Kroll, J. H.; Ng, N. L.; Zhang, Y.-H.; Lin, Y.; Xue, L.; Sun, T.-L.; Liu, X.-G.; Shao, M.; Jayne, J. T.; Worsnop, D. R.

2010-11-01

The Pearl River Delta (PRD) region in South China is one of the most economically developed regions in China, but it is also noted for its severe air pollution due to industrial/metropolitan emissions. In order to continuously improve the understanding and quantification of air pollution in this region, an intensive campaign was executed in PRD during October-November 2008. Here, we report and analyze Aerodyne High-Resolution Aerosol Mass Spectrometer measurements at Kaiping, a rural site downwind of the highly-polluted central PRD area, to characterize the general features of submicron particulate pollution in the regional air. The mean measured PM1 mass concentration was 33.1 ± 18.1 μg m-3 during the campaign and composed of organic matter (33.8%), sulfate (33.7%), ammonium (14.0%), nitrate (10.7%), black carbon (6.7%), and chloride (1.1%), which is characterized by high fractions of inorganic ions due to huge emissions of SO2 and NOx in PRD. The average size distributions of the species (except BC) were all dominated by an accumulation mode peaking at ~450 nm in vacuum aerodynamic diameter. Calculations based on high-resolution organic mass spectra indicate that C, H, O, and N on average contributed 56.6, 7.0, 35.1, and 1.3% to the total organic mass, respectively, corresponding to an organic matter mass to organic carbon mass ratio (OM/OC) of 1.77 ± 0.08. Based on the high-resolution organic mass spectral dataset observed, Positive Matrix Factorization (PMF) analysis differentiated the organic aerosol into three components, i.e., biomass burning (BBOA) and two oxygenated (LV-OOA and SV-OOA) organic aerosols, which on average accounted for 24.5, 39.6 and 35.8% of the total organic mass, respectively. The BBOA showed strong features of biomass burning emissions and has been mainly attributed to field rice straw burning after harvest. The LV-OOA and SV-OOA were found to correspond to more aged (and thus less-volatile) and fresher (and semi-volatile) secondary

Coupling a versatile aerosol apparatus to a synchrotron: Vacuum ultraviolet light scattering, photoelectron imaging, and fragment free mass spectrometry

NASA Astrophysics Data System (ADS)

Shu, Jinian; Wilson, Kevin R.; Ahmed, Musahid; Leone, Stephen R.

2006-04-01

An aerosol apparatus has been coupled to the Chemical Dynamics Beamline of the Advanced Light Source at Lawrence Berkeley National Laboratory. This apparatus has multiple capabilities for aerosol studies, including vacuum ultraviolet (VUV) light scattering, photoelectron imaging, and mass spectroscopy of aerosols. By utilizing an inlet system consisting of a 200μm orifice nozzle and aerodynamic lenses, aerosol particles of ˜50nm-˜1μm in diameter can be sampled directly from atmospheric pressure. The machine is versatile and can probe carbonaceous aerosols generated by a laboratory flame, nebulized solutions of biological molecules, hydrocarbon aerosol reaction products, and synthesized inorganic nanoparticles. The sensitivity of this apparatus is demonstrated by the detection of nanoparticles with VUV light scattering, photoelectron imaging, and charged particle detection. In addition to the detection of nanoparticles, the thermal vaporization of aerosols on a heater tip leads to the generation of intact gas phase molecules. This phenomenon coupled to threshold single photon ionization, accessible with tunable VUV light, allows for fragment-free mass spectrometry of complex molecules. The initial experiments with light scattering, photoelectron imaging, and aerosol mass spectrometry reported here serve as a demonstration of the design philosophy and multiple capabilities of the apparatus.

A study on contraction of pneumatic artificial muscle (PAM) for load-lifting

NASA Astrophysics Data System (ADS)

Najmuddin, W. S. W. A.; Mustaffa, M. T.

2017-10-01

Pneumatic Artificial Muscles (PAMs) have been known for its wide application in various aspects of industrial automation and robotic equipments. Many advantages in terms of high power-to-volume ratio, high power-to-weight ratio, stick-slip-free operation and high degree of safety offer by PAM compare to traditional actuators. However, behind this benefits lie a limitation of significant compatibility of PAM mechanism which have to be considered so as to fully understand how the PAM works during load-lifting. In this study, the mesh suitability experiment and the effect of force load on PAM contraction experiment have been carried out. PAM is constructed and compatibility of bladder and the braided mesh to produce uniform expansion is investigated. Moreover, the first experimental result of finding compatibility is used to verify the contraction value under various loads.

Understanding the Critical Parameters of the PAMS Mandrel Fabrication Process

DOE PAGES

Bhandarkar, Suhas; Paguio, Reny; Elsner, Fred; ...

2016-07-05

As a part of an effort to continually better the roundness and roughness of ablator capsules, we looked at improving the same for the poly(alphamethylstyrene) or PAMS mandrels used to make the plastic capsules. The importance of this work is based on the fact that the surface properties of the mandrels set the lower limit for the ultimate attributes of the ablator capsule. These mandrels are made using an elegant double-emulsion process that uses the isotropic forces brought about by hydrostatic pressure and interfacial tension to seek sphericity. This paper describes the reasoning that led to investigating the so-called curingmore » process where a solid PAMS shell is generated from a solution phase for achieving this goal. Using modeling to account for the mass transfer of the fluorobenzene solvent phase, we demonstrate that it is the control of the conditions through the percolation point of the system that leads to better mandrels. These concepts were implemented into the fabrication process to demonstrate significant improvements of the roundness of the mandrels.« less

Simulating Aerosol Size Distribution and Mass Concentration with Simultaneous Nucleation, Condensation/Coagulation, and Deposition with the GRAPES-CUACE

NASA Astrophysics Data System (ADS)

Zhou, Chunhong; Shen, Xiaojing; Liu, Zirui; Zhang, Yangmei; Xin, Jinyuan

2018-04-01

A coupled aerosol-cloud model is essential for investigating the formation of haze and fog and the interaction of aerosols with clouds and precipitation. One of the key tasks of such a model is to produce correct mass and number size distributions of aerosols. In this paper, a parameterization scheme for aerosol size distribution in initial emission, which took into account the measured mass and number size distributions of aerosols, was developed in the GRAPES-CUACE [Global/Regional Assimilation and PrEdiction System-China Meteorological Administration (CMA) Unified Atmospheric Chemistry Environment model]—an online chemical weather forecast system that contains microphysical processes and emission, transport, and chemical conversion of sectional multi-component aerosols. In addition, the competitive mechanism between nucleation and condensation for secondary aerosol formation was improved, and the dry deposition was also modified to be in consistent with the real depositing length. Based on the above improvements, the GRAPES-CUACE simulations were verified against observational data during 1-31 January 2013, when a series of heavy regional haze-fog events occurred in eastern China. The results show that the aerosol number size distribution from the improved experiment was much closer to the observation, whereas in the old experiment the number concentration was higher in the nucleation mode and lower in the accumulation mode. Meanwhile, the errors in aerosol number size distribution as diagnosed by its sectional mass size distribution were also reduced. Moreover, simulations of organic carbon, sulfate, and other aerosol components were improved and the overestimation as well as underestimation of PM2.5 concentration in eastern China was significantly reduced, leading to increased correlation coefficient between simulated and observed PM2.5 by more than 70%. In the remote areas where bad simulation results were produced previously, the correlation coefficient

Desorption atmospheric pressure photoionization high-resolution mass spectrometry: a complementary approach for the chemical analysis of atmospheric aerosols.

PubMed

Parshintsev, Jevgeni; Vaikkinen, Anu; Lipponen, Katriina; Vrkoslav, Vladimir; Cvačka, Josef; Kostiainen, Risto; Kotiaho, Tapio; Hartonen, Kari; Riekkola, Marja-Liisa; Kauppila, Tiina J

2015-07-15

On-line chemical characterization methods of atmospheric aerosols are essential to increase our understanding of physicochemical processes in the atmosphere, and to study biosphere-atmosphere interactions. Several techniques, including aerosol mass spectrometry, are nowadays available, but they all suffer from some disadvantages. In this research, desorption atmospheric pressure photoionization high-resolution (Orbitrap) mass spectrometry (DAPPI-HRMS) is introduced as a complementary technique for the fast analysis of aerosol chemical composition without the need for sample preparation. Atmospheric aerosols from city air were collected on a filter, desorbed in a DAPPI source with a hot stream of toluene and nitrogen, and ionized using a vacuum ultraviolet lamp at atmospheric pressure. To study the applicability of the technique for ambient aerosol analysis, several samples were collected onto filters and analyzed, with the focus being on selected organic acids. To compare the DAPPI-HRMS data with results obtained by an established method, each filter sample was divided into two equal parts, and the second half of the filter was extracted and analyzed by liquid chromatography/mass spectrometry (LC/MS). The DAPPI results agreed with the measured aerosol particle number. In addition to the targeted acids, the LC/MS and DAPPI-HRMS methods were found to detect different compounds, thus providing complementary information about the aerosol samples. DAPPI-HRMS showed several important oxidation products of terpenes, and numerous compounds were tentatively identified. Thanks to the soft ionization, high mass resolution, fast analysis, simplicity and on-line applicability, the proposed methodology has high potential in the field of atmospheric research. Copyright © 2015 John Wiley & Sons, Ltd.

Measurements of Size Resolved Organic Particulate Mass Using An On-line Aerosol Mass Spectrometer (ams) Laboratory Validation; Analysis Tool Development; and Interpretation of Field Data

NASA Astrophysics Data System (ADS)

Alfarra, M. R.; Coe, H.; Allan, J. D.; Bower, K. N.; Garforth, A. A.; Canagaratna, M.; Worsnop, D.

The aerosol mass spectrometer (AMS) is a quantitative instrument designed to deliver real-time size resolved chemical composition of the volatile and semi volatile aerosol fractions. The AMS response to a wide range of organic compounds has been exper- imentally characterized, and has been shown to compare well with standard libraries of 70 eV electron impact ionization mass spectra. These results will be presented. Due to the scanning nature of the quadrupole mass spectrometer, the AMS provides averaged composition of ensemble of particles rather than single particle composi- tion. However, the mass spectra measured by AMS are reproducible and similar to those of standard libraries so analysis tools can be developed on large mass spectral libraries that can provide chemical composition information about the type of organic compounds in the aerosol. One such tool is presented and compared with laboratory measurements of single species and mixed component organic particles by the AMS. We will then discuss the applicability of these tools to interpreting field AMS data ob- tained in a range of experiments at different sites in the UK and Canada. The data will be combined with other measurements to show the behaviour of the organic aerosol fraction in urban and sub-urban environments.

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

NASA Astrophysics Data System (ADS)

Nemuc, A.; Vasilescu, J.; Talianu, C.; Belegante, L.; Nicolae, D.

2013-11-01

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

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

NASA Astrophysics Data System (ADS)

Nemuc, A.; Vasilescu, J.; Talianu, C.; Belegante, L.; Nicolae, D.

2013-06-01

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

Analysis of Marine Aerosol Polysaccharides by Pyrolysis Time-of-Flight Mass Spectrometry

NASA Astrophysics Data System (ADS)

Lawler, M. J.; Grieman, M. M.; Sengur, I.; Saltzman, E. S.

2017-12-01

The relationship between surface ocean biological productivity and marine cloud formation and properties has been explored for decades, but the impacts of marine biogenic emissions on cloudiness and climate remain highly uncertain. This is in part due to the challenge of directly linking biogenic materials in the surface ocean with cloud-forming aerosol. It has been shown that polysaccharide gel-forming materials, also known as transparent exopolymers, may be mechanically ejected from the sea surface during air bubble bursting (Leck and Bigg, 2005). Existing analysis methods for such aerosols require considerable sample mass and sample preparation. As part of the multi-year seasonal North Atlantic Aerosols and Marine Ecosystems Study (NAAMES), ambient submicron marine aerosol was collected in November 2015 and May 2016 from the R/V Atlantis at using a Particle into Liquid Sampler (PILS). These samples of roughly 15 minute time resolution were frozen and returned to UC Irvine for analysis. A new technique has been developed to attempt to quantify polysaccharide material in these ambient samples. A small subsample (1- 5 µL) is taken from the PILS vial samples and allowed to dry on a Pt ribbon filament in the chemical ionization source region of a time-of-flight mass spectrometer. The sample then undergoes a two-step heating process, in which volatilizable molecules are first desorbed and then non-volatilizable large molecules such as polysaccharides are pyrolyzed. These desorbed molecules and decomposition products are ionized using either O2- or H3O+ reagent ion and are directly sampled into the mass spectrometer. The resulting spectra can then be compared to standards of known polysaccharide materials for quantification and potentially structural and/or compositional information.

Characterizing aerosol transport into the Canadian High Arctic using aerosol mass spectrometry and Lagrangian modelling

NASA Astrophysics Data System (ADS)

Kuhn, T.; Damoah, R.; Bacak, A.; Sloan, J. J.

2010-05-01

We report the analysis of measurements made using an aerosol mass spectrometer (AMS; Aerodyne Research Inc.) that was installed in the Polar Environment Atmospheric Research Laboratory (PEARL) in summer 2006. PEARL is located in the Canadian high Arctic at 610 m above sea level on Ellesmere Island (80° N 86° W). PEARL is unique for its remote location in the Arctic and because most of the time it is situated within the free troposphere. It is therefore well suited as a receptor site to study the long range tropospheric transport of pollutants into the Arctic. Some information about the successful year-round operation of an AMS at a high Arctic site such as PEARL will be reported here, together with design considerations for reliable sampling under harsh low-temperature conditions. Computational fluid dynamics calculations were made to ensure that sample integrity was maintained while sampling air at temperatures that average -40 °C in the winter and can be as low as -55 °C. Selected AMS measurements of aerosol mass concentration, size, and chemical composition recorded during the months of August, September and October 2006 will be reported. During this period, sulfate was at most times the predominant aerosol component with on average 0.115 μg m-3 (detection limit 0.003 μg m-3). The second most abundant component was undifferentiated organic aerosol, with on average 0.11 μg m-3 detection limit (0.04 μg m-3). The nitrate component, which averaged 0.007 μg m-3, was above its detection limit (0.002 μg m-3), whereas the ammonium ion had an apparent average concentration of 0.02 μg m-3, which was approximately equal to its detection limit. A few episodes having increased mass concentrations and lasting from several hours to several days are apparent in the data. These were investigated further using a statistical analysis to determine their common characteristics. High correlations among some of the components arriving during the short term episodes provide

Experimental Characterization and Hygroscopicity Determination of Secondary Aerosol from D5 Cyclic Siloxane Oxidation

NASA Astrophysics Data System (ADS)

Stanier, C. O.; Janechek, N. J.; Bryngelson, N.; Marek, R. F.; Lersch, T.; Bunker, K.; Casuccio, G.; Brune, W. H.; Hornbuckle, K. C.

2017-12-01

Cyclic volatile methyl siloxanes are anthropogenic chemicals present in personal care products such as antiperspirants and lotions. These are volatile chemicals that are readily released into the atmosphere by product use. Due to their emission and relatively slow kinetics of their major transformation pathway, reaction with hydroxyl radicals (OH), these compounds are present in high concentrations in indoor environments and widespread in outdoor environments. Cyclic siloxane reaction with OH can lead to secondary organic aerosols, and due to the widespread prevalence of the parent compounds, may be an important source of ambient aerosols. Atmospheric aerosols have important influences to the climate by affecting the radiative balance and by serving as cloud condensation nuclei (CCN) which influence clouds. While the parent compounds have been well-studied, the oxidation products have received much less attention, with almost no ambient measurements or experimental physical property data. We report physical properties of aerosols generated by reacting the cyclic siloxane D5 with OH using a Potential Aerosol Mass (PAM) photochemical chamber. The particles were characterized by SMPS, imaging and elemental analysis using both Transmission Electron Microscopy and Scanning Transmission Electron Microscopy equipped with Energy Dispersive X-ray Spectroscopy systems (TEM-EDS and STEM-EDS), volatility measurements using Volatility Tandem Differential Mobility Analyzer (V-TDMA), and hygroscopicity measurements to determine CCN potential using a Droplet Measurement Technologies Cloud Condensation Nuclei Counter (DMT-CCN). Aerosol yield sensitivity to D5 and OH concentrations, residence time, and seed aerosols were analyzed. TEM-EDS and STEM-EDS analysis show spherical particle morphology with elemental composition consistent with aerosols derived from cyclic siloxane sources. Measured aerosol yields were 20-50% with typical aerosol concentrations 300,000 particles cm-3, up to

Evolution of wavelength-dependent mass absorption cross sections of carbonaceous aerosols during the 2010 DOE CARES campaign

NASA Astrophysics Data System (ADS)

Flowers, B. A.; Dubey, M. K.; Subramanian, R.; Sedlacek, A. J.; Kelley, P.; Luke, W. T.; Jobson, B. T.; Zaveri, R. A.

2011-12-01

Predictions of aerosol radiative forcing require process level optical property models that are built on precise and accurate field observations. Evolution of aerosol optical properties for urban influenced carbonaceous aerosol undergoing transport and mixing with rural air masses was a focal point of the DOE Carbonaceous Aerosol and Radiative Effects (CARES) campaign near Sacramento, CA in summer 2010. Urban aerosol was transported from Sacramento, CA (T0) to the foothills of the Sierra Nevada Mountains to a rural site located near Cool, CA (T1). Aerosol absorption and scattering coefficients were measured at the T0 and T1 sites using integrated photoacoustic acoustic/nephelometer instruments (PASS-3 and PASS-UV) at 781, 532, 405, and 375 nm. Single particle soot photometry (SP2) instrumentation was used to monitor black carbon (BC) mass at both sites. Combining data from these sensors allows estimate of the wavelength-dependent mass absorption coefficient (MAC(λ)) and partitioning of MAC(λ) into contributions from the BC core and from enhancements from coating of BC cores. MAC(λ) measured in this way is free of artifacts associated with filter-based aerosol absorption measurements and takes advantage of the single particle sensitivity of the SP2 instrument, allowing observation of MAC(λ) on 10 minute and faster time scales. Coating was observed to enhance MAC(λ) by 20 - 30 % and different wavelength dependence for MAC(λ) was observed for urban and biomass burning aerosol. Further, T0 - T1 evolution of MAC(λ) was correlated with separately measured NO/NOy ratios and CO/CO2 ratios to understand the effects of aging & transport on MAC(λ) and the implications of aerosol processing that links air quality to radiative forcing on a regional scale. Aircraft observations made from the Gulfstream-1 during CARES are also analyzed to enhance process level understanding of the optical properties of fresh and aged carbonaceous aerosol in the urban-rural interface.

Real-time measurement of sodium chloride in individual aerosol particles by mass spectrometry

NASA Technical Reports Server (NTRS)

Sinha, M. P.; Friedlander, S. K.

1985-01-01

The method of particle analysis by mass spectrometry has been applied to the quantitative measurement of sodium chloride in individual particles on a real-time basis. Particles of known masses are individually introduced, in the form of a beam, into a miniature Knudsen cell oven (1600 K). The oven is fabricated from rhenium metal sheet (0.018 mm thick) and is situated in the ion source of a quadrupole mass spectrometer. A particle once inside the oven is trapped and completely volatilized; this overcomes the problem of partial volatilization due to particles bouncing from the filament surface. Individual particles are thermally volatilized and ionized inside the rhenium oven, and produce discrete sodium ion pulses whose intensities are measured with the quadrupole mass spectrometer. An ion pulse width of several milliseconds (4-12 ms) is found for particles in the mass range 1.3 x 10 to the -13th to 5.4 x 10 to the -11th g. The sodium ion intensity is found to be proportional to the particle mass to the 0.86-power. The intensity distribution for monodisperse aerosol particles possesses a geometric standard deviation of 1.09, showing that the method can be used for the determination of the mass distribution function with good resolution in a polydisperse aerosol.

Characterization of aerosol composition and sources in the greater Atlanta area by aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Ng, N. L.; Xu, L.; Suresh, S.; Weber, R. J. J.; Baumann, K.; Edgerton, E. S.

2014-12-01

An important and uncertain aspect of biogenic secondary organic aerosol (SOA) formation is that it is often associated with anthropogenic pollution tracers. Prior studies in Atlanta suggested that 70-80% of the carbon in water-soluble organic carbon (WSOC) is modern, yet it is well-correlated with the anthropogenic CO. In this study, we deployed a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) at multiple sites in different seasons (May 2012-February 2013) to characterize the sources and chemical composition of aerosols in the greater Atlanta area. This area in the SE US is ideal to investigate anthropogenic-biogenic interactions due to high natural and anthropogenic emissions. These extensive field studies are part of the Southeastern Center for Air Pollution and Epidemiology study (SCAPE). The HR-ToF-AMS is deployed at four sites (~ 3 weeks each) in rotation: Jefferson Street (urban), Yorkville (rural), roadside site (near Highway 75/85), and Georgia Tech site (campus), with the urban and rural sites being part of the SEARCH network. We obtained seven HR-ToF-AMS datasets in total. During the entire measurement period, the ACSM is stationary at the GIT site and samples continuously. We perform positive matrix factorization (PMF) analysis on the HR-ToF-AMS and ACSM data to deconvolve the OA into different components. While the diurnal cycle of the total OA is flat as what have been previously observed, the OA factors resolved by PMF analysis show distinctively different diurnal trends. We find that the "more-oxidized oxygenated OA" (MO-OOA) constitutes a major fraction of OA at all sites. In summer, OA is dominated by SOA, e.g., isoprene-OA and OOA with different degrees of oxidation. In contrary, biomass burning OA is more prominent in winter data. By comparing HR-ToF-AMS and ACSM data during the same sampling periods, we find that the aerosol time series are highly correlated, indicating the

Performance Comparison of 112-Gb/s DMT, Nyquist PAM4, and Partial-Response PAM4 for Future 5G Ethernet-Based Fronthaul Architecture

NASA Astrophysics Data System (ADS)

Eiselt, Nicklas; Muench, Daniel; Dochhan, Annika; Griesser, Helmut; Eiselt, Michael; Olmos, Juan Jose Vegas; Monroy, Idelfonso Tafur; Elbers, Joerg-Peter

2018-05-01

For a future 5G Ethernet-based fronthaul architecture, 100G trunk lines of a transmission distance up to 10 km standard single mode fiber (SSMF) in combination with cheap grey optics to daisy chain cell site network interfaces are a promising cost- and power-efficient solution. For such a scenario, different intensity modulation and direct detect (IMDD) Formats at a data rate of 112 Gb/s, namely Nyquist four-level pulse amplitude modulation (PAM4), discrete multi-tone Transmission (DMT) and partial-response (PR) PAM4 are experimentally investigated, using a low-cost electro-absorption modulated laser (EML), a 25G driver and current state-of-the-art high Speed 84 GS/s CMOS digital-to-analog converter (DAC) and analog-to-digital converter (ADC) test chips. Each modulation Format is optimized independently for the desired scenario and their digital signal processing (DSP) requirements are investigated. The performance of Nyquist PAM4 and PR PAM4 depend very much on the efficiency of pre- and post-equalization. We show the necessity for at least 11 FFE-taps for pre-emphasis and up to 41 FFE coefficients at the receiver side. In addition, PR PAM4 requires an MLSE with four states to decode the signal back to a PAM4 signal. On the contrary, bit- and power-loading (BL, PL) is crucial for DMT and an FFT length of at least 512 is necessary. With optimized parameters, all Modulation formats result in a very similar performances, demonstrating a transmission distance of up to 10 km over SSMF with bit error rates (BERs) below a FEC threshold of 4.4E-3, allowing error free transmission.

Impact of aerosol size representation on modeling aerosol-cloud interactions

DOE PAGES

Zhang, Y.; Easter, R. C.; Ghan, S. J.; ...

2002-11-07

In this study, we use a 1-D version of a climate-aerosol-chemistry model with both modal and sectional aerosol size representations to evaluate the impact of aerosol size representation on modeling aerosol-cloud interactions in shallow stratiform clouds observed during the 2nd Aerosol Characterization Experiment. Both the modal (with prognostic aerosol number and mass or prognostic aerosol number, surface area and mass, referred to as the Modal-NM and Modal-NSM) and the sectional approaches (with 12 and 36 sections) predict total number and mass for interstitial and activated particles that are generally within several percent of references from a high resolution 108-section approach.more » The modal approach with prognostic aerosol mass but diagnostic number (referred to as the Modal-M) cannot accurately predict the total particle number and surface areas, with deviations from the references ranging from 7-161%. The particle size distributions are sensitive to size representations, with normalized absolute differences of up to 12% and 37% for the 36- and 12-section approaches, and 30%, 39%, and 179% for the Modal-NSM, Modal-NM, and Modal-M, respectively. For the Modal-NSM and Modal-NM, differences from the references are primarily due to the inherent assumptions and limitations of the modal approach. In particular, they cannot resolve the abrupt size transition between the interstitial and activated aerosol fractions. For the 12- and 36-section approaches, differences are largely due to limitations of the parameterized activation for non-log-normal size distributions, plus the coarse resolution for the 12-section case. Differences are larger both with higher aerosol (i.e., less complete activation) and higher SO2 concentrations (i.e., greater modification of the initial aerosol distribution).« less

Measurements of Semi-volatile Aerosol and Its Effect on Aerosol Optical Properties During Southern Oxidant and Aerosol Study

NASA Astrophysics Data System (ADS)

Khlystov, A.; Grieshop, A. P.; Saha, P.; Subramanian, R.

2013-12-01

Semi-volatile compounds, including particle-bound water, comprise a large part of aerosol mass and have a significant influence on aerosol lifecycle and its optical properties. Understanding the properties of semi-volatile compounds, especially those pertaining to gas/aerosol partitioning, is of critical importance for our ability to predict concentrations and properties of ambient aerosol. A set of state-of-the-art instruments was deployed at the SEARCH site near Centerville, AL during the Southern Oxidant and Aerosol Study (SOAS) campaign in summer 2013 to measure the effect of temperature and relative humidity on aerosol size distribution, composition and optical properties. Light scattering and absorption by temperature- and humidity-conditioned aerosols was measured using three photo-acoustic extinctiometers (PAX) at three wavelengths (405 nm, 532 nm, and 870 nm). In parallel to these measurements, a long residence time temperature-stepping thermodenuder and a variable residence time constant temperature thermodenuder in combination with three SMPS systems and an Aerosol Chemical Speciation Monitor (ACSM) were used to assess aerosol volatility and kinetics of aerosol evaporation. It was found that both temperature and relative humidity have a strong effect on aerosol optical properties. The variable residence time thermodenuder data suggest that aerosol equilibrated fairly quickly, within 2 s, in contrast to other ambient observations. Preliminary analysis show that approximately 50% and 90% of total aerosol mass evaporated at temperatures of 100 C and 180C, respectively. Evaporation varied substantially with ambient aerosol loading and composition and meteorology. During course of this study, T50 (temperatures at which 50% aerosol mass evaporates) varied from 60 C to more than 120 C.

New insights into modeling an organic mass fraction of sea spray aerosol

NASA Astrophysics Data System (ADS)

Meskhidze, N.; Gantt, B.

2010-12-01

As the study of climate change progresses, a need to separate the effects of natural and anthropogenic processes becomes essential in order to correctly forecast the future climate. Due to their massive source regions underlying an atmosphere with low aerosol concentration, marine aerosols derived from sea spray and ocean emitted biogenic volatile organic compounds (BVOCs) are extremely important for the Earth’s radiative budget, regional air quality and biogeochemical cycling of elements. Measurements of freshly-emitted sea spray have revealed that bubble bursting processes, largely responsible for the production of sea salt aerosol, also control sea-to-air transfer of marine organic matter. It has been established that the organic mass fraction of sea spray can be a function of sea-water composition (e.g., concentrations of Chlorophyll-a, [Chl-a], dissolved organic carbon, [DOC], particulate organic carbon, [POC], types of organic carbon, and the amount of surfactants). Current paramaterizations of marine primary organic aerosol emissions use remotely sensed [Chl-a] data as a proxy for oceanic biological activity. However, it has also been shown that the path length, size, and lifetime of bubbles in seawater as well as spatial coverage of seawater surface by streaks or slicks (visible film of a roughly 50 μm thick layer, highly enriched in organics) can have dramatic effect on organic mass fraction of sea spray (OCss). Dynamics of bubble entrainment and the level of microlayer enrichment by organics relative to the underlying bulk water can be controlled by surface wind speed. For bubble entrainment, high winds can increase rising bubble path length and therefore the amount of organics scavenged by the bubble. However, when the surface wind speeds exceed 8 m s-1 breaking of ocean waves can entirely destroy surface organic films and diminish the amount of organics leaving the sea. Despite the probable impact of wind speed, existing parameterizations do not

Inverse effects of Polyacrylamide (PAM) usage in furrow irrigation on advance time and deep percolation.

PubMed

Meral, Ramazan; Cemek, Bilal; Apan, Mehmet; Merdun, Hasan

2006-10-01

The positive effects of Polyacrylamide (PAM), which is used as a soil conditioner in furrow irrigation, on sediment transport, erosion, and infiltration have been investigated intensively in recent years. However, the effects of PAM have not been considered enough in irrigation system planning and design. As a result of increased infiltration because of PAM, advance time may be inversely affected and deep percolation increases. However, advance time in furrow irrigation is a crucial parameter in order to get high application efficiency. In this study, inverse effects of PAM were discussed, and as an alternative solution, the applicability of surge flow was investigated. PAM application significantly increased the advance time at the rates of 41.3-56.3% in the first irrigation. The application of surge flow with PAM removed this negative effect on advance time, where there was no statistically significant difference according to normal continuous flow (without PAM). PAM applications significantly increased the deep percolation, 80.3-117.1%. Surge flow with PAM had significantly positive effect on the deep percolation compared to continuous flow with PAM but not compared to normal continuous flow. These results suggested that irrigation planning should me made based on the new soil and flow conditions because of PAM usage, and surge flow can be a solution to these problems.

PAM4 silicon photonic microring resonator-based transceiver circuits

NASA Astrophysics Data System (ADS)

Palermo, Samuel; Yu, Kunzhi; Roshan-Zamir, Ashkan; Wang, Binhao; Li, Cheng; Seyedi, M. Ashkan; Fiorentino, Marco; Beausoleil, Raymond

2017-02-01

Increased data rates have motivated the investigation of advanced modulation schemes, such as four-level pulseamplitude modulation (PAM4), in optical interconnect systems in order to enable longer transmission distances and operation with reduced circuit bandwidth relative to non-return-to-zero (NRZ) modulation. Employing this modulation scheme in interconnect architectures based on high-Q silicon photonic microring resonator devices, which occupy small area and allow for inherent wavelength-division multiplexing (WDM), offers a promising solution to address the dramatic increase in datacenter and high-performance computing system I/O bandwidth demands. Two ring modulator device structures are proposed for PAM4 modulation, including a single phase shifter segment device driven with a multi-level PAM4 transmitter and a two-segment device driven by two simple NRZ (MSB/LSB) transmitters. Transmitter circuits which utilize segmented pulsed-cascode high swing output stages are presented for both device structures. Output stage segmentation is utilized in the single-segment device design for PAM4 voltage level control, while in the two-segment design it is used for both independent MSB/LSB voltage levels and impedance control for output eye skew compensation. The 65nm CMOS transmitters supply a 4.4Vppd output swing for 40Gb/s operation when driving depletion-mode microring modulators implemented in a 130nm SOI process, with the single- and two-segment designs achieving 3.04 and 4.38mW/Gb/s, respectively. A PAM4 optical receiver front-end is also described which employs a large input-stage feedback resistor transimpedance amplifier (TIA) cascaded with an adaptively-tuned continuous-time linear equalizer (CTLE) for improved sensitivity. Receiver linearity, critical in PAM4 systems, is achieved with a peak-detector-based automatic gain control (AGC) loop.

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

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

Pam2 lipopeptides systemically increase myeloid-derived suppressor cells through TLR2 signaling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maruyama, Akira; Shime, Hiroaki, E-mail: shime@med.hokudai.ac.jp; Takeda, Yohei

2015-02-13

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells that exhibit potent immunosuppressive activity. They are increased in tumor-bearing hosts and contribute to tumor development. Toll-like receptors (TLRs) on MDSCs may modulate the tumor-supporting properties of MDSCs through pattern-recognition. Pam2 lipopeptides represented by Pam2CSK4 serve as a TLR2 agonist to exert anti-tumor function by dendritic cell (DC)-priming that leads to NK cell activation and cytotoxic T cell proliferation. On the other hand, TLR2 enhances tumor cell progression/invasion by activating tumor-infiltrating macrophages. How MDSCs respond to TLR2 agonists has not yet been determined. In this study, we found intravenous administration of Pam2CSK4more » systemically up-regulated the frequency of MDSCs in EG7 tumor-bearing mice. The frequency of tumor-infiltrating MDSCs was accordingly increased in response to Pam2CSK4. MDSCs were not increased by Pam2CSK4 stimuli in TLR2 knockout (KO) mice. Adoptive transfer experiments using CFSE-labeled MDSCs revealed that the TLR2-positive MDSCs survived long in tumor-bearing mice in response to Pam2CSK4 treatment. Since the increased MDSC population sustained immune-suppressive properties, our study suggests that Pam2CSK4-triggered TLR2 activation enhances the MDSC potential and suppress antitumor immune response in tumor microenvironment. - Highlights: • Pam2CSK4 administration induces systemic accumulation of CD11b{sup +}Gr1{sup +} MDSCs. • TLR2 is essential for Pam2CSK4-induced accumulation of CD11b{sup +}Gr1{sup +} MDSCs. • Pam2CSK4 supports survival of CD11b{sup +}Gr1{sup +} MDSCs in vivo.« less

Comparison of primary and secondary particle formation from natural gas engine exhaust and of their volatility characteristics

NASA Astrophysics Data System (ADS)

Alanen, Jenni; Simonen, Pauli; Saarikoski, Sanna; Timonen, Hilkka; Kangasniemi, Oskari; Saukko, Erkka; Hillamo, Risto; Lehtoranta, Kati; Murtonen, Timo; Vesala, Hannu; Keskinen, Jorma; Rönkkö, Topi

2017-07-01

Natural gas usage in the traffic and energy production sectors is a growing trend worldwide; thus, an assessment of its effects on air quality, human health and climate is required. Engine exhaust is a source of primary particulate emissions and secondary aerosol precursors, which both contribute to air quality and can cause adverse health effects. Technologies, such as cleaner engines or fuels, that produce less primary and secondary aerosols could potentially significantly decrease atmospheric particle concentrations and their adverse effects. In this study, we used a potential aerosol mass (PAM) chamber to investigate the secondary aerosol formation potential of natural gas engine exhaust. The PAM chamber was used with a constant UV-light voltage, which resulted in relatively long equivalent atmospheric ages of 11 days at most. The studied retro-fitted natural gas engine exhaust was observed to form secondary aerosol. The mass of the total aged particles, i.e., particle mass measured downstream of the PAM chamber, was 6-268 times as high as the mass of the emitted primary exhaust particles. The secondary organic aerosol (SOA) formation potential was measured to be 9-20 mg kgfuel-1. The total aged particles mainly consisted of organic matter, nitrate, sulfate and ammonium, with the fractions depending on exhaust after-treatment and the engine parameters used. Also, the volatility, composition and concentration of the total aged particles were found to depend on the engine operating mode, catalyst temperature and catalyst type. For example, a high catalyst temperature promoted the formation of sulfate particles, whereas a low catalyst temperature promoted nitrate formation. However, in particular, the concentration of nitrate needed a long time to stabilize - more than half an hour - which complicated the conclusions but also indicates the sensitivity of nitrate measurements on experimental parameters such as emission source and system temperatures. Sulfate was

Multiday production of condensing organic aerosol mass in urban and forest outflow

DOE PAGES

Lee-Taylor, J.; Hodzic, A.; Madronich, S.; ...

2014-07-03

Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for several days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (∼50%) and of shorter duration (1–2 days). The production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products ofmore » both aromatics and alkanes. In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

Structural Basis for the Altered PAM Recognition by Engineered CRISPR-Cpf1.

PubMed

Nishimasu, Hiroshi; Yamano, Takashi; Gao, Linyi; Zhang, Feng; Ishitani, Ryuichiro; Nureki, Osamu

2017-07-06

The RNA-guided Cpf1 nuclease cleaves double-stranded DNA targets complementary to the CRISPR RNA (crRNA), and it has been harnessed for genome editing technologies. Recently, Acidaminococcus sp. BV3L6 (AsCpf1) was engineered to recognize altered DNA sequences as the protospacer adjacent motif (PAM), thereby expanding the target range of Cpf1-mediated genome editing. Whereas wild-type AsCpf1 recognizes the TTTV PAM, the RVR (S542R/K548V/N552R) and RR (S542R/K607R) variants can efficiently recognize the TATV and TYCV PAMs, respectively. However, their PAM recognition mechanisms remained unknown. Here we present the 2.0 Å resolution crystal structures of the RVR and RR variants bound to a crRNA and its target DNA. The structures revealed that the RVR and RR variants primarily recognize the PAM-complementary nucleotides via the substituted residues. Our high-resolution structures delineated the altered PAM recognition mechanisms of the AsCpf1 variants, providing a basis for the further engineering of CRISPR-Cpf1. Copyright © 2017 Elsevier Inc. All rights reserved.

Gaseous composition measured by a chemical ionization mass spectrometer in fresh and aged ship plumes

NASA Astrophysics Data System (ADS)

Faxon, Cameron; Psichoudaki, Magda; Kuuluvainen, Heino; Hallquist, Åsa; Thomson, Erik; Pettersson, Jan; Hallquist, Mattias

2015-04-01

The port of Gothenburg is the largest port of the Nordic countries with numerous ships calling the port daily. The ship exhausts contain numerous pollutants including gases such as SO2 and NOx as well as particulate matter and soot. The exhaust also contains numerous organic compounds, a large fraction of which are unidentified. These organics are oxidized in the atmosphere producing more oxygenated and potentially less volatile compounds that may contribute to the secondary organic aerosol (SOA). This work focuses on the characterization of fresh gaseous species present in the exhaust plumes of the passing ships and also on their photochemical aging. Between 26 September and 12 November 2014 measurements were conducted at a sampling site located on a small peninsula at the entrance of Gothenburg's port. The campaign was divided in two periods. During the first period, the fresh plumes of the passing ships were measured through a main inlet. During the second period, the sample passed through the same inlet and was then introduced into a Potential Aerosol Mass (PAM) reactor. The PAM reactor uses UV lamps and high concentrations of oxidants (OH radicals and O3) to oxidize the organic species present in the plumes. The oxidation that takes place within the reactor can be equivalent to up to one week of atmospheric oxidation. Preliminary tests showed that the oxidation employed in the current camping corresponded to 3.4 days in the atmosphere. A Time-of-Flight Chemical Ionization Mass Spectrometer (ToF-CIMS) was employed to monitor the concentration of different organic species present in the fresh and aged plumes. Water (positive) and iodide (negative) ionization methods were employed were water was primarily used for fresh plumes (large fraction of non-polar compounds) while iodide was used for the aged plumes (primarily oxidised products). The H2O, O3 and SO2 concentrations inside the PAM chamber were monitored, and an organic tracer for OH exposure determination

Aerosol mass spectrometric features of biogenic SOA: observations from a plant chamber and in rural atmospheric environments.

PubMed

Kiendler-Scharr, Astrid; Zhang, Qi; Hohaus, Thorsten; Kleist, Einhard; Mensah, Amewu; Mentel, Thomas F; Spindler, Christian; Uerlings, Ricarda; Tillmann, Ralf; Wildt, Jürgen

2009-11-01

Secondary organic aerosol (SOA) is known to form from a variety of anthropogenic and biogenic precursors. Current estimates of global SOA production vary over 2 orders of magnitude. Since no direct measurement technique for SOA exists, quantifying SOA remains a challenge for atmospheric studies. The identification of biogenic SOA (BSOA) based on mass spectral signatures offers the possibility to derive source information of organic aerosol (OA) with high time resolution. Here we present data from simulation experiments. The BSOA from tree emissions was characterized with an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS). Collection efficiencies were close to 1, and effective densities of the BSOA were found to be 1.3 +/- 0.1 g/cm(3). The mass spectra of SOA from different trees were found to be highly similar. The average BSOA mass spectrum from tree emissions is compared to a BSOA component spectrum extracted from field data. It is shown that overall the spectra agree well and that the mass spectral features of BSOA are distinctively different from those of OA components related to fresh fossil fuel and biomass combustions. The simulation chamber mass spectrum may potentially be useful for the identification and interpretation of biogenic SOA components in ambient data sets.

A new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra

NASA Astrophysics Data System (ADS)

Heringa, M. F.; Decarlo, P. F.; Chirico, R.; Tritscher, T.; Clairotte, M.; Mohr, C.; Crippa, M.; Slowik, J. G.; Pfaffenberger, L.; Dommen, J.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.

2012-02-01

Organic aerosol (OA) represents a significant and often major fraction of the non-refractory PM1 (particulate matter with an aerodynamic diameter da < 1 μm) mass. Secondary organic aerosol (SOA) is an important contributor to the OA and can be formed from biogenic and anthropogenic precursors. Here we present results from the characterization of SOA produced from the emissions of three different anthropogenic sources. SOA from a log wood burner, a Euro 2 diesel car and a two-stroke Euro 2 scooter were characterized with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and compared to SOA from α-pinene. The emissions were sampled from the chimney/tailpipe by a heated inlet system and filtered before injection into a smog chamber. The gas phase emissions were irradiated by xenon arc lamps to initiate photo-chemistry which led to nucleation and subsequent particle growth by SOA production. Duplicate experiments were performed for each SOA type, with the averaged organic mass spectra showing Pearson's r values >0.94 for the correlations between the four different SOA types after five hours of aging. High-resolution mass spectra (HR-MS) showed that the dominant peaks in the MS, m/z 43 and 44, are dominated by the oxygenated ions C2H3O+ and CO2+, respectively, similarly to the relatively fresh semi-volatile oxygenated OA (SV-OOA) observed in the ambient aerosol. The atomic O:C ratios were found to be in the range of 0.25-0.55 with no major increase during the first five hours of aging. On average, the diesel SOA showed the lowest O:C ratio followed by SOA from wood burning, α-pinene and the scooter emissions. Grouping the fragment ions revealed that the SOA source with the highest O:C ratio had the largest fraction of small ions. The HR data of the four sources could be clustered and separated using principal component analysis (PCA). The model showed a significant separation of the four SOA types and clustering of the duplicate

Chemical composition and characteristics of ambient aerosols and rainwater residues during Indian summer monsoon: Insight from aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Chakraborty, Abhishek; Gupta, Tarun; Tripathi, Sachchida N.

2016-07-01

Real time composition of non-refractory submicron aerosol (NR-PM1) is measured via Aerosol mass spectrometer (AMS) for the first time during Indian summer monsoon at Kanpur, a polluted urban location located at the heart of Indo Gangetic Plain (IGP). Submicron aerosols are found to be dominated by organics followed by nitrate. Source apportionment of organic aerosols (OA) via positive matrix factorization (PMF) revealed several types of secondary/oxidized and primary organic aerosols. On average, OA are completely dominated by oxidized OA with a very little contribution from biomass burning OA. During rain events, PM1 concentration is decreased almost by 60%, but its composition remains nearly the same. Oxidized OA showed slightly more decrease than primary OAs, probably due to their higher hygroscopicity. The presence of organo nitrates (ON) is also detected in ambient aerosols. Apart from real-time sampling, collected fog and rainwater samples were also analyzed via AMS in offline mode and in the ICP-OES (Inductively coupled plasma - Optical emission spectrometry) for elements. The presence of sea salt, organo nitrates and sulfates has been observed. Rainwater residues are also dominated by organics but their O/C ratios are 15-20% lower than the observed values for ambient OA. Alkali metals such as Ca, Na, K are found to be most abundant in the rainwater followed by Zn. Rainwater residues are also found to be much less oxidized than the aerosols present inside the fog water, indicating presence of less oxidized organics. These findings indicate that rain can act as an effective scavenger of different types of pollutants even for submicron particle range. Rainwater residues also contain organo sulfates which indicate that some portion of the dissolved aerosols has undergone aqueous processing, possibly inside the cloud. Highly oxidized and possibly hygroscopic OA during monsoon period compared to other seasons (winter, post monsoon), indicates that they can act

Characterization of primary organic aerosol emissions from meat cooking, trash burning, and motor vehicles with high-resolution aerosol mass spectrometry and comparison with ambient and chamber observations.

PubMed

Mohr, Claudia; Huffman, Alex; Cubison, Michael J; Aiken, Allison C; Docherty, Kenneth S; Kimmel, Joel R; Ulbrich, Ingrid M; Hannigan, Michael; Jimenez, Jose L

2009-04-01

Organic aerosol (OA) emissions from motor vehicles, meat-cooking and trash burning are analyzed here using a high-resolution aerosol mass spectrometer (AMS). High resolution data show that aerosols emitted by combustion engines and plastic burning are dominated by hydrocarbon-like organic compounds. Meat cooking and especially paper burning emissions contain significant fractions of oxygenated organic compounds; however, their unit-resolution mass spectral signatures are very similar to those from ambient hydrocarbon-like OA, and very different from the mass spectra of ambient secondary or oxygenated OA (OOA). Thus, primary OA from these sources is unlikelyto be a significant direct source of ambient OOA. There are significant differences in high-resolution tracer m/zs that may be useful for differentiating some of these sources. Unlike in most ambient spectra, all of these sources have low total m/z 44 and this signal is not dominated by the CO2+ ion. All sources have high m/z 57, which is low during high OOA ambient periods. Spectra from paper burning are similar to some types of biomass burning OA, with elevated m/z 60. Meat cooking aerosols also have slightly elevated m/z 60, whereas motor vehicle emissions have very low signal at this m/z.

Gasoline emissions dominate over diesel in formation of secondary organic aerosol mass

NASA Astrophysics Data System (ADS)

Bahreini, R.; Middlebrook, A. M.; de Gouw, J. A.; Warneke, C.; Trainer, M.; Brock, C. A.; Stark, H.; Brown, S. S.; Dube, W. P.; Gilman, J. B.; Hall, K.; Holloway, J. S.; Kuster, W. C.; Perring, A. E.; Prevot, A. S. H.; Schwarz, J. P.; Spackman, J. R.; Szidat, S.; Wagner, N. L.; Weber, R. J.; Zotter, P.; Parrish, D. D.

2012-03-01

Although laboratory experiments have shown that organic compounds in both gasoline fuel and diesel engine exhaust can form secondary organic aerosol (SOA), the fractional contribution from gasoline and diesel exhaust emissions to ambient SOA in urban environments is poorly known. Here we use airborne and ground-based measurements of organic aerosol (OA) in the Los Angeles (LA) Basin, California made during May and June 2010 to assess the amount of SOA formed from diesel emissions. Diesel emissions in the LA Basin vary between weekdays and weekends, with 54% lower diesel emissions on weekends. Despite this difference in source contributions, in air masses with similar degrees of photochemical processing, formation of OA is the same on weekends and weekdays, within the measurement uncertainties. This result indicates that the contribution from diesel emissions to SOA formation is zero within our uncertainties. Therefore, substantial reductions of SOA mass on local to global scales will be achieved by reducing gasoline vehicle emissions.

Preliminary observations of organic gas-particle partitioning from biomass combustion smoke using an aerosol mass spectrometer

Treesearch

T. Lee; S. M. Kreidenweis; J. L. Collett; A. P. Sullivan; C. M. Carrico; J. L. Jimenez; M. Cubison; S. Saarikoski; D. R. Worsnop; T. B. Onasch; E. Fortner; W. C. Malm; E. Lincoln; Cyle Wold; WeiMin Hao

2010-01-01

Aerosols play important roles in adverse health effects, indirect and direct forcing of Earth’s climate, and visibility degradation. Biomass burning emissions from wild and prescribed fires can make a significant contribution to ambient aerosol mass in many locations and seasons. In order to better understand the chemical properties of particles produced by combustion...

Methods for decoding Cas9 protospacer adjacent motif (PAM) sequences: A brief overview.

PubMed

Karvelis, Tautvydas; Gasiunas, Giedrius; Siksnys, Virginijus

2017-05-15

Recently the Cas9, an RNA guided DNA endonuclease, emerged as a powerful tool for targeted genome manipulations. Cas9 protein can be reprogrammed to cleave, bind or nick any DNA target by simply changing crRNA sequence, however a short nucleotide sequence, termed PAM, is required to initiate crRNA hybridization to the DNA target. PAM sequence is recognized by Cas9 protein and must be determined experimentally for each Cas9 variant. Exploration of Cas9 orthologs could offer a diversity of PAM sequences and novel biochemical properties that may be beneficial for genome editing applications. Here we briefly review and compare Cas9 PAM identification assays that can be adopted for other PAM-dependent CRISPR-Cas systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Haloarcula hispanica CRISPR authenticates PAM of a target sequence to prime discriminative adaptation

PubMed Central

Li, Ming; Wang, Rui; Xiang, Hua

2014-01-01

The prokaryotic immune system CRISPR/Cas (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated genes) adapts to foreign invaders by acquiring their short deoxyribonucleic acid (DNA) fragments as spacers, which guide subsequent interference to foreign nucleic acids based on sequence matching. The adaptation mechanism avoiding acquiring ‘self’ DNA fragments is poorly understood. In Haloarcula hispanica, we previously showed that CRISPR adaptation requires being primed by a pre-existing spacer partially matching the invader DNA. Here, we further demonstrate that flanking a fully-matched target sequence, a functional PAM (protospacer adjacent motif) is still required to prime adaptation. Interestingly, interference utilizes only four PAM sequences, whereas adaptation-priming tolerates as many as 23 PAM sequences. This relaxed PAM selectivity explains how adaptation-priming maximizes its tolerance of PAM mutations (that escape interference) while avoiding mis-targeting the spacer DNA within CRISPR locus. We propose that the primed adaptation, which hitches and cooperates with the interference pathway, distinguishes target from non-target by CRISPR ribonucleic acid guidance and PAM recognition. PMID:24803673

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

NASA Technical Reports Server (NTRS)

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

1986-01-01

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

Mass-spectrometric identification of primary biological particle markers: indication for low abundance of primary biological material in the pristine submicron aerosol of Amazonia

NASA Astrophysics Data System (ADS)

Schneider, J.; Freutel, F.; Zorn, S. R.; Chen, Q.; Farmer, D. K.; Jimenez, J. L.; Martin, S. T.; Artaxo, P.; Wiedensohler, A.; Borrmann, S.

2011-07-01

The abundance of marker compounds for primary biological particles in submicron aerosol was investigated by means of aerosol mass spectrometry. Mass spectra of amino acids, carbohydrates, small peptides, and proteins, all of which are key building blocks of biological particles, were recorded in laboratory experiments. Several characteristic marker peaks were identified. The identified marker peaks were compared with mass spectra recorded during AMAZE-08, a field campaign conducted in the pristine rainforest of the Central Amazon Basin, Brazil, during the wet season of February and March 2008. The low abundance of identified marker peaks places upper limits of 7.5 % for amino acids and 5.6 % for carbohydrates on the contribution of primary biological aerosol particles (PBAPs) to the submicron organic aerosol mass concentration during this time period. Upper limits for the absolute submicron concentrations for both compound classes range from 0.01 to 0.1 μg m-3. Carbohydrates and protein amino acids make up for about two thirds of the dry mass of a biological cell. Thus, our findings suggest an upper limit for the PBAPs mass fraction of about 20 % to the submicron organic aerosol.

Borotungstic Acid (BWA)-Polyacrylamide (PAM) Solid Polymer Electrolytes for Electrochemical Capacitors

NASA Astrophysics Data System (ADS)

Foong, Yee Wei

Solid polymer electrolytes (SPEs) are key enablers for thin and flexible electrochemical capacitors in wearable technologies. Polyacrylamide (PAM) is one such promising hygroscopic polymer host, but its performance had not been optimized. This thesis enhanced PAM with borotungstic acid (BWA) as the heteropolyacid conductors. The BWA-PAM electrolyte achieved a high initial conductivity of ca. 27 mS cm-1, but suffered from a short service life (< 40% conductivity retention after 28 days) due to dehydration. BWA-PAM modified with acidic (H3PO4) and neutral (glycerol) plasticizers showed improved conductivity of ca. 30 mS cm-1 and service life (≥ 70% conductivity retention after 28 days). The high BWA and H3PO4 content accelerated the hydrolysis of PAM to polyacrylic acid, resulting in the undesirable precipitation of NH4+-substituted BWA; whereas, glycerol was found to suppress this reaction. The solid CNT-graphite cells with the optimized electrolytes demonstrated a capacitance of ca. 19.5 mF cm -2; a high rate capability (≥ 75% capacitance retention) at 1Vs -1; excellent cycle life (≥ 90% retention of its initial capacitance); and maintained ca. -85° phase angle over 10,000 charging-discharging cycles.

USDA-ARS perspective on PAM

USDA-ARS?s Scientific Manuscript database

Polyacrylamide (PAM) described herein is a synthetic organic polymer used globally by a number of important industries. It also has a number of valuable applications in irrigated agriculture, including its use in furrow irrigation to control erosion and sediment loss in runoff, manage infiltration,...

Wind tunnel experimental study on the effect of PAM on soil wind erosion control.

PubMed

He, Ji-Jun; Cai, Qiang-Guo; Tang, Ze-Jun

2008-10-01

In recent years, high-molecular-weight anionic polyacrylamide (PAM) have been widely tested on a variety of soils, primarily in water erosion control. However, little information is available regarding the effectiveness of PAM on preventing soil loss from wind erosion. The research adopted room wind tunnel experiment, two kinds of soils were used which were from the agro-pastoral area of Inner Mongolia, the northwest of China, the clay content of soils were 22.0 and 13.7%, respectively. For these tests, all the treatments were performed under the condition of wind velocity of 14 m s(-1) and a blown angle of 8.75%, according to the actual situation of experimented area. The study results indicated that using PAM on the soil surface could enhance the capability of avoiding the wind erosion, at the same time, the effect of controlling wind soil erosion with 4 g m(-2) PAM was better than 2 g m(-2) PAM's. Economically, the 2 g m(-2) PAM used in soil surface can control wind erosion effectively in this region. The prophase PAM accumulated in soil could not improve the capability of avoiding the wind erosion, owing to the degradation of PAM in the soil and the continual tillage year after year. The texture of soil is a main factor influencing the capability of soil avoiding wind erosion. Soil with higher clay content has the higher capability of preventing soil from wind erosion than one with the opposite one under the together action of PAM and water.

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.

Multiday production of condensing organic aerosol mass in urban and forest outflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee-Taylor, J.; Hodzic, A.; Madronich, S.

2015-01-16

Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1–2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction productsmore » of both aromatics and alkanes, especially those with relatively low carbon numbers (C4–15). In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

Multiday production of condensing organic aerosol mass in urban and forest outflow

DOE PAGES

Lee-Taylor, J.; Hodzic, A.; Madronich, S.; ...

2015-01-16

Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1–2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction productsmore » of both aromatics and alkanes, especially those with relatively low carbon numbers (C4–15). In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. Here, the results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

Novel glycolipid TLR2 ligands of the type Pam2Cys-α-Gal: synthesis and biological properties.

PubMed

Thomann, Jean-Sébastien; Monneaux, Fanny; Creusat, Gaëlle; Spanedda, Maria Vittoria; Heurtault, Béatrice; Habermacher, Chloé; Schuber, Francis; Bourel-Bonnet, Line; Frisch, Benoît

2012-05-01

A more complete understanding of the mechanism of action of TLR agonists has fueled the investigation of new synthetic immunoadjuvants. In this context, we designed and synthesized glycolipids of the type Pam(2)Cys-α-Galactose as novel immunoadjuvants. Their synthesis required modifying a hydrophobic tBoc-[2,3-bispalmitoyloxy-(2R)-propyl]-R-cysteinyl moiety, i.e. the minimal structure required for TLR2 agonist activity, by addition of a hydrophilic head, either an α-Galactosylpyranose or an α-Galactosylfuranose to gain respectively Pam(2)CGalp and Pam(2)CGalf. While preparing a carbohydrate building block, an unexpected stereoselectivity was observed during a halide ion-catalytic process on a protected galactofuranose: the alpha anomer was obtained with surprisingly high selectivity (α/β ratio>9) and with good isolated yield (51%). The TLR2 binding properties of Pam(2)CGalp and Pam(2)CGalf were then fully evaluated. Their efficiency in triggering the proliferation of BALB/c mouse splenocytes was also compared to that of Pam(2)CAG and Pam(3)CAG, two well-established ligands of TLRs. Moreover, the maturation state of murine dendritic cells previously incubated with either Pam(2)CGalp or Pam(2)CGalf was monitored by flow cytometry and compared to that induced by lipopolysaccharide. Pam(2)CGalp and Pam(2)CGalf were found to be equivalent TLR2 agonists, and induced splenocyte proliferation and DC maturation. With very similar activity, Pam(2)CGalp and Pam(2)CGalf were also 10-fold to 100-fold better than Pam(2)CAG and Pam(3)CAG at inducing B cell proliferation. This represents the first time a glucidic head has been added to the tBoc-[2,3-bispalmitoyloxy-(2R)-propyl]-R-cysteinyl moiety whilst maintaining the immunomodulating activity. This should greatly enrich the data available on Pam(2)C structure/activity relationships. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

A study on the relationship between mass concentrations, chemistry and number size distribution of urban fine aerosols in Milan, Barcelona and London

NASA Astrophysics Data System (ADS)

Rodríguez, S.; van Dingenen, R.; Putaud, J.-P.; Dell'Acqua, A.; Pey, J.; Querol, X.; Alastuey, A.; Chenery, S.; Ho, K.-F.; Harrison, R.; Tardivo, R.; Scarnato, B.; Gemelli, V.

2007-05-01

A physicochemical characterization, including aerosol number size distribution, chemical composition and mass concentrations, of the urban fine aerosol captured in MILAN, BARCELONA and LONDON is presented in this article. The objective is to obtain a comprehensive picture of the microphysical processes involved in aerosol dynamics during the: 1) regular evolution of the urban aerosol (daily, weekly and seasonal basis) and in the day-to-day variations (from clean-air to pollution-events), and 2) the link between "aerosol chemistry and mass concentrations" with the "number size distribution". The mass concentrations of the fine PM2.5 aerosol exhibit a high correlation with the number concentration of >100 nm particles N>100 (nm) ("accumulation mode particles") which only account for <20% of the total number concentration N of fine aerosols; but do not correlate with the number of <100 nm particles ("ultrafine particles"), which accounts for >80% of fine particles number concentration. Organic matter and black-carbon are the only aerosol components showing a significant correlation with the ultrafine particles, attributed to vehicles exhausts emissions; whereas ammonium-nitrate, ammonium-sulphate and also organic matter and black-carbon correlate with N>100 (nm) and attributed to condensation mechanisms, other particle growth processes and some primary emissions. Time series of the aerosol DpN diameter (dN/dlogD mode), mass PM2.5 concentrations and number N>100 (nm) concentrations exhibit correlated day-to-day variations, which point to a significant involvement of condensation of semi-volatile compounds during urban pollution events. This agrees with the observation that ammonium-nitrate is the component exhibiting the highest increases from mid-to-high pollution episodes, when the highest DpN increases are observed. The results indicates that "fine PM2.5 particles urban pollution events" tend to occur when condensation processes have made particles grow large enough

A passive and active microwave-vector radiative transfer (PAM-VRT) model

NASA Astrophysics Data System (ADS)

Yang, Jun; Min, Qilong

2015-11-01

A passive and active microwave vector radiative transfer (PAM-VRT) package has been developed. This fast and accurate forward microwave model, with flexible and versatile input and output components, self-consistently and realistically simulates measurements/radiation of passive and active microwave sensors. The core PAM-VRT, microwave radiative transfer model, consists of five modules: gas absorption (two line-by-line databases and four fast models); hydrometeor property of water droplets and ice (spherical and nonspherical) particles; surface emissivity (from Community Radiative Transfer Model (CRTM)); vector radiative transfer of successive order of scattering (VSOS); and passive and active microwave simulation. The PAM-VRT package has been validated against other existing models, demonstrating good accuracy. The PAM-VRT not only can be used to simulate or assimilate measurements of existing microwave sensors, but also can be used to simulate observation results at some new microwave sensors.

Sensitivity of Aerosol Mass and Microphysics to Treatments of Condensational Growth of Secondary Organic Compounds in a Regional Model

NASA Astrophysics Data System (ADS)

Topping, D. O.; Lowe, D.; McFiggans, G.; Zaveri, R. A.

2016-12-01

Gas to particle partitioning of atmospheric compounds occurs through disequilibrium mass transfer rather than through instantaneous equilibrium. However, it is common to treat only the inorganic compounds as partitioning dynamically whilst organic compounds, represented by the Volatility Basis Set (VBS), are partitioned instantaneously. In this study we implement a more realistic dynamic partitioning of organic compounds in a regional framework and assess impact on aerosol mass and microphysics. It is also common to assume condensed phase water is only associated with inorganic components. We thus also assess sensitivity to assuming all organics are hygroscopic according to their prescribed molecular weight.For this study we use WRF-Chem v3.4.1, focusing on anthropogenic dominated North-Western Europe. Gas-phase chemistry is represented using CBM-Z whilst aerosol dynamics are simulated using the 8-section MOSAIC scheme, including a 9-bin volatility basis set (VBS) treatment of organic aerosol. Results indicate that predicted mass loadings can vary significantly. Without gas phase ageing of higher volatility compounds, dynamic partitioning always results in lower mass loadings downwind of emission sources. The inclusion of condensed phase water in both partitioning models increases the predicted PM mass, resulting from a larger contribution from higher volatility organics, if present. If gas phase ageing of VBS compounds is allowed to occur in a dynamic model, this can often lead to higher predicted mass loadings, contrary to expected behaviour from a simple non-reactive gas phase box model. As descriptions of aerosol phase processes improve within regional models, the baseline descriptions of partitioning should retain the ability to treat dynamic partitioning of organic compounds. Using our simulations, we discuss whether derived sensitivities to aerosol processes in existing models may be inherently biased.This work was supported by the Nature Environment

PAM: A Program for Adolescent Mothers.

ERIC Educational Resources Information Center

Robichaux, Faye B.; And Others

1989-01-01

Describes the Program for Adolescent Mothers (PAM) established to provide opportunities for teen mothers in Louisiana to increase their self-esteem, become productive citizens, and become aware of the physical and emotional development of children. (JOW)

Improved identification of primary biological aerosol particles using single-particle mass spectrometry

DOE PAGES

Zawadowicz, Maria A.; Froyd, Karl D.; Murphy, Daniel M.; ...

2017-06-16

Measurements of primary biological aerosol particles (PBAP), especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture) using SPMS. Here, we show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodologymore » to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04–2 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36–56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust–biological mixtures.« less

Improved identification of primary biological aerosol particles using single-particle mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zawadowicz, Maria A.; Froyd, Karl D.; Murphy, Daniel M.

Measurements of primary biological aerosol particles (PBAP), especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture) using SPMS. Here, we show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodologymore » to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04–2 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36–56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust–biological mixtures.« less

Improved identification of primary biological aerosol particles using single-particle mass spectrometry

NASA Astrophysics Data System (ADS)

Zawadowicz, Maria A.; Froyd, Karl D.; Murphy, Daniel M.; Cziczo, Daniel J.

2017-06-01

Measurements of primary biological aerosol particles (PBAP), especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture) using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04-2 % of particles in the 200-3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36-56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust-biological mixtures.

Variability of aerosol, gaseous pollutants and meteorological characteristics associated with changes in air mass origin at the SW Atlantic coast of Iberia

NASA Astrophysics Data System (ADS)

Diesch, J.-M.; Drewnick, F.; Zorn, S. R.; von der Weiden-Reinmüller, S.-L.; Martinez, M.; Borrmann, S.

2012-04-01

Measurements of the ambient aerosol were performed at the Southern coast of Spain, within the framework of the DOMINO (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) project. The field campaign took place from 20 November until 9 December 2008 at the atmospheric research station "El Arenosillo" (37°5'47.76" N, 6°44'6.94" W). As the monitoring station is located at the interface between a natural park, industrial cities (Huelva, Seville) and the Atlantic Ocean, a variety of physical and chemical parameters of aerosols and gas phase could be characterized in dependency on the origin of air masses. Backwards trajectories were examined and compared with local meteorology to classify characteristic air mass types for several source regions. Aerosol number and mass as well as polycyclic aromatic hydrocarbons and black carbon concentrations were measured in PM1 and size distributions were registered covering a size range from 7 nm up to 32 μm. The chemical composition of the non-refractory submicron aerosol (NR-PM1) was measured by means of an Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS). Gas phase analyzers monitored various trace gases (O3, SO2, NO, NO2, CO2) and a weather station provided meteorological parameters. Lowest average submicron particle mass and number concentrations were found in air masses arriving from the Atlantic Ocean with values around 2 μg m-3 and 1000 cm-3. These mass concentrations were about two to four times lower than the values recorded in air masses of continental and urban origins. For some species PM1-fractions in marine air were significantly larger than in air masses originating from Huelva, a closely located city with extensive industrial activities. The largest fraction of sulfate (54%) was detected in marine air masses and was to a high degree not neutralized. In addition, small concentrations of methanesulfonic acid (MSA), a product of biogenic dimethyl sulfate (DMS) emissions, could be identified in the particle phase

Response of an aerosol mass spectrometer to organonitrates and organosulfates and implications for atmospheric chemistry

PubMed Central

Farmer, D. K.; Matsunaga, A.; Docherty, K. S.; Surratt, J. D.; Seinfeld, J. H.; Ziemann, P. J.; Jimenez, J. L.

2010-01-01

Organonitrates (ON) are important products of gas-phase oxidation of volatile organic compounds in the troposphere; some models predict, and laboratory studies show, the formation of large, multifunctional ON with vapor pressures low enough to partition to the particle phase. Organosulfates (OS) have also been recently detected in secondary organic aerosol. Despite their potential importance, ON and OS remain a nearly unexplored aspect of atmospheric chemistry because few studies have quantified particulate ON or OS in ambient air. We report the response of a high-resolution time-of-flight aerosol mass spectrometer (AMS) to aerosol ON and OS standards and mixtures. We quantify the potentially substantial underestimation of organic aerosol O/C, commonly used as a metric for aging, and N/C. Most of the ON-nitrogen appears as ions in the AMS, which are typically dominated by inorganic nitrate. Minor organonitrogen ions are observed although their identity and intensity vary between standards. We evaluate the potential for using fragment ratios, organonitrogen ions, ions, the ammonium balance of the nominally inorganic ions, and comparison to ion-chromatography instruments to constrain the concentrations of ON for ambient datasets, and apply these techniques to a field study in Riverside, CA. OS manifests as separate organic and sulfate components in the AMS with minimal organosulfur fragments and little difference in fragmentation from inorganic sulfate. The low thermal stability of ON and OS likely causes similar detection difficulties for other aerosol mass spectrometers using vaporization and/or ionization techniques with similar or larger energy, which has likely led to an underappreciation of these species. PMID:20194777

Fractal morphology, imaging and mass spectrometry of single aerosol particles in flight (CXIDB ID 16)

DOE Data Explorer

Loh, N. Duane

2012-06-20

This deposition includes the aerosol diffraction images used for phasing, fractal morphology, and time-of-flight mass spectrometry. Files in this deposition are ordered in subdirectories that reflect the specifics.

Detecting trace pesticides in real time using single particle aerosol mass spectrometry.

PubMed

Barker, Zachary; Venkatchalam, Veena; Martin, Audrey N; Farquar, George R; Frank, Matthias

2010-02-28

Pesticides are toxic substances and may cause unintentional harm if improperly used. The ubiquitous nature of pesticides, with frequent use in agriculture and the household, and the potential for harm that pesticides pose to non-target organisms such as wildlife, humans, and pets, demonstrate the need for rapid and effective detection and identification of these compounds. In this study, single particle aerosol mass spectrometry (SPAMS) was used to rapidly detect compounds from four classes of pesticides commonly used in agricultural and household applications. These include permethrin (pyrethroid class), malathion and dichlorvos (organophosphate class), imidacloprid (chloronicotinyl class), and carbaryl (carbamate class). Analytical standards of each compound were diluted and aerosolized using a nebulizer to create particles for analysis in the SPAMS instrument. The resultant dual-polarity time-of-flight mass spectra were then analyzed to identify the characteristic peaks of the compound in each sample. In addition, samples of commercial products containing pesticides, a commercial insecticide spray, containing permethrin, and a canine flea collar, containing carbaryl, were analyzed in their original form using SPAMS without any significant sample preparation. The characteristic mass spectral peaks of the active pesticides in these samples were identified using the mass spectra obtained earlier from the pesticide analytical standards. By successfully identifying pesticides in analytical standards and in commercial products, it is demonstrated herein that the SPAMS system may be capable of pesticide detection in numerous environmental and agricultural situations. Copyright 2010 Elsevier B.V. All rights reserved.

Gas phase emissions from cooking processes and their secondary aerosol production potential

NASA Astrophysics Data System (ADS)

Klein, Felix; Platt, Stephen; Bruns, Emily; Termime-roussel, Brice; Detournay, Anais; Mohr, Claudia; Crippa, Monica; Slowik, Jay; Marchand, Nicolas; Baltensperger, Urs; Prevot, Andre; El Haddad, Imad

2014-05-01

Long before the industrial evolution and the era of fossil fuels, high concentrations of aerosol particles were alluded to in heavily populated areas, including ancient Rome and medieval London. Recent radiocarbon measurements (14C) conducted in modern megacities came as a surprise: carbonaceous aerosol (mainly organic aerosol, OA), a predominant fraction of particulate matter (PM), remains overwhelmingly non-fossil despite extensive fossil fuel combustion. Such particles are directly emitted (primary OA, POA) or formed in-situ in the atmosphere (secondary OA, SOA) via photochemical reactions of volatile organic compounds (VOCs). Urban levels of non-fossil OA greatly exceed the levels measured in pristine environments strongly impacted by biogenic emissions, suggesting a contribution from unidentified anthropogenic non-fossil sources to urban OA. Positive matrix factorization (PMF) techniques applied to ambient aerosol mass spectrometer (AMS, Aerodyne) data identify primary cooking emissions (COA) as one of the main sources of primary non-fossil OA in major cities like London (Allan et al., 2010), New York (Sun et al., 2011) and Beijing (Huang et al., 2010). Cooking processes can also emit VOCs that can act as SOA precursors, potentially explaining in part the high levels of oxygenated OA (OOA) identified by the AMS in urban areas. However, at present, the chemical nature of these VOCs and their secondary aerosol production potential (SAPP) remain virtually unknown. The approach adopted here involves laboratory quantification of PM and VOC emission factors from the main primary COA emitting processes and their SAPP. Primary emissions from deep-fat frying, vegetable boiling, vegetable frying and meat cooking for different oils, meats and vegetables were analysed under controlled conditions after ~100 times dilution. A high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a high resolution proton transfer time-of-flight mass spectrometer (PTR

Towards depth profiling of organic aerosols in real time using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

NASA Astrophysics Data System (ADS)

Brüggemann, Martin; Hoffmann, Thorsten

2014-05-01

Organic aerosol accounts for a substantial fraction of tropospheric aerosol and has implications on the earth's climate and human health. However, the characterization of its chemical composition and transformations remain a major challenge and is still connected to large uncertainties (IPCC, 2013). Recent measurements revealed that organic aerosol particles may reside in an amorphous or semi-solid phase state which impedes the diffusion within the particles (Virtanen et al., 2010; Shiraiwa et al., 2011). This means that reaction products which are formed on the surface of a particle, e.g. by OH, NO3 or ozone chemistry, cannot diffuse into the particle's core and remain at the surface. Eventually, this leads to particles with a core/shell structure. In the particles' cores the initial compounds are preserved whereas the shells contain mainly the oxidation products. By analyzing the particles' cores and shells separately, thus, it is possible to obtain valuable information on the formation and evolution of the aerosols' particle and gas phase. Here we present the development of the aerosol flowing atmospheric-pressure afterglow (AeroFAPA) technique which allows the mass spectrometric analysis of organic aerosols in real time. The AeroFAPA is an ion source based on a helium glow discharge at atmospheric pressure. The plasma produces excited helium species and primary reagent ions which are transferred into the afterglow region where the ionization of the analytes takes place. Due to temperatures of only 80 ° C to 150 ° C and ambient pressure in the afterglow region, the ionization is very soft and almost no fragmentation of organic molecules is observed. Thus, the obtained mass spectra are easy to interpret and no extensive data analysis procedure is necessary. Additionally, first results of a combination of the AeroFAPA-MS with a scanning mobility particle sizer (SMPS) suggest that it is not only possible to analyze the entire particle phase but rather that a

A study on the relationship between mass concentrations, chemistry and number size distribution of urban fine aerosols in Milan, Barcelona and London

NASA Astrophysics Data System (ADS)

Rodríguez, S.; van Dingenen, R.; Putaud, J.-P.; Dell'Acqua, A.; Pey, J.; Querol, X.; Alastuey, A.; Chenery, S.; Ho, K.-F.; Harrison, R. M.; Tardivo, R.; Scarnato, B.; Gianelle, V.

2007-01-01

A physicochemical characterization of the urban fine aerosol (aerosol number size distribution, chemical composition and mass concentrations) in Milan, Barcelona and London is presented in this article. The objective is to obtain a comprehensive picture on the involvement of the microphysical processes of the aerosol dynamic in the: 1) regular evolution of the urban aerosol (daily, weekly and seasonal basis) and in the day-to-day variations (from clean-air to pollution-events), and 2) link between "aerosol chemistry and mass concentrations" with the "number size distribution". The mass concentrations of the fine PM2.5 aerosol exhibit a high correlation with the number concentration of particles >100 nm (which only accounts for <20% of the total number concentration N of fine aerosols) and do not correlate with the number of particles <100 nm ("ultrafine particles", which accounts for >80% of fine particles). Organic matter (OM) and black-carbon (BC) are the only aerosol components showing a significant correlation with ultrafine particles (attributed to vehicles emissions), whereas ammonium-nitrate, ammonium-sulphate and also OM and BC correlate with N>100(nm) (attributed to gas-to-particle transformation mechanisms and some primary emissions). Time series of the aerosol DpN diameter (dN/dlogD mode), mass PM2.5 concentrations and number N>100(nm) concentrations, exhibit correlated day-to-day variations which point to a significant involvement of condensation of semi-volatile compounds during urban pollution events. This agrees with the fact that ammonium-nitrate is the component exhibiting the highest increases from mid-to-high pollution episodes, when the highest DpN increases are observed. The results indicates that "fine PM2.5 particles urban pollution events" tend to occur when condensation processes have made particles grow enough to produce significant concentrations of N>100(nm). In contrast, because the low contribution of ultrafine particles to the fine

Is there an aerosol signature of aqueous processing?

NASA Astrophysics Data System (ADS)

Ervens, B.; Sorooshian, A.

2017-12-01

The formation of aerosol mass in cloud water has been recognized as a substantial source of atmospheric aerosol mass. While sulfate formation can be relatively well constrained, the formation of secondary organic aerosol mass in the aqueous phase (aqSOA) is much more complex due to the multitude of precursors and variety in chemical processes. Aqueous phase processing adds aerosol mass to the droplet mode, which is formed due to mass addition to activated particles in clouds. In addition, it has been shown that aqSOA mass has specific characteristics in terms of oxidation state and hygroscopicity that might help to distinguish it from other SOA sources. Many models do not include detailed chemical mechanisms of sulfate and aqSOA formation and also lack details on the mass distribution of newly formed mass. Mass addition inside and outside clouds modifies different parts of an aerosol population and consequently affects predictions of properties and lifetime of particles. Using a combination of field data analysis and model studies for a variety of air masses, we will show which chemical and physical aerosol properties can be used, in order to identify an `aqueous phase signature' in processed aerosol populations. We will discuss differences in this signature in clean (e.g., background), moderately polluted (e.g., urban) and highly polluted (e.g., biomass burning) air masses and suggest air-mass-specific chemical and/or physical properties that will help to quantify the aqueous-phase derived aerosol mass.

Sensitivity of Aerosol Mass and Microphysics to varying treatments of Condensational Growth of Secondary Organic Compounds in a regional model

NASA Astrophysics Data System (ADS)

Lowe, Douglas; Topping, David; McFiggans, Gordon

2017-04-01

Gas to particle partitioning of atmospheric compounds occurs through disequilibrium mass transfer rather than through instantaneous equilibrium. However, it is common to treat only the inorganic compounds as partitioning dynamically whilst organic compounds, represented by the Volatility Basis Set (VBS), are partitioned instantaneously. In this study we implement a more realistic dynamic partitioning of organic compounds in a regional framework and assess impact on aerosol mass and microphysics. It is also common to assume condensed phase water is only associated with inorganic components. We thus also assess sensitivity to assuming all organics are hygroscopic according to their prescribed molecular weight. For this study we use WRF-Chem v3.4.1, focusing on anthropogenic dominated North-Western Europe. Gas-phase chemistry is represented using CBM-Z whilst aerosol dynamics are simulated using the 8-section MOSAIC scheme, including a 9-bin VBS treatment of organic aerosol. Results indicate that predicted mass loadings can vary significantly. Without gas phase ageing of higher volatility compounds, dynamic partitioning always results in lower mass loadings downwind of emission sources. The inclusion of condensed phase water in both partitioning models increases the predicted PM mass, resulting from a larger contribution from higher volatility organics, if present. If gas phase ageing of VBS compounds is allowed to occur in a dynamic model, this can often lead to higher predicted mass loadings, contrary to expected behaviour from a simple non-reactive gas phase box model. As descriptions of aerosol phase processes improve within regional models, the baseline descriptions of partitioning should retain the ability to treat dynamic partitioning of organics compounds. Using our simulations, we discuss whether derived sensitivities to aerosol processes in existing models may be inherently biased. This work was supported by the Natural Environment Research Council within

Antarctic aerosols - A review

NASA Astrophysics Data System (ADS)

Shaw, Glenn E.

1988-02-01

Tropospheric aerosols with the diameter range of half a micron reside in the atmosphere for tens of days and teleconnect Antarctica with other regions by transport that reaches planetary scales of distances; thus, the aerosol on the Antarctic ice represents 'memory modules' of events that took place at regions separated from Antarctica by tens of thousands of kilometers. In terms of aerosol mass, the aerosol species include insoluble crustal products (less than 5 percent), transported sea-salt residues (highly variable but averaging about 10 percent), Ni-rich meteoric material, and anomalously enriched material with an unknown origin. Most (70-90 percent by mass) of the aerosol over the Antarctic ice shield, however, is the 'natural acid sulfate aerosol', apparently deriving from biological processes taking place in the surrounding oceans.

Variability of aerosol, gaseous pollutants and meteorological characteristics associated with continental, urban and marine air masses at the SW Atlantic coast of Iberia

NASA Astrophysics Data System (ADS)

Diesch, J.-M.; Drewnick, F.; Zorn, S. R.; von der Weiden-Reinmüller, S.-L.; Martinez, M.; Borrmann, S.

2011-12-01

Measurements of the ambient aerosol were performed at the Southern coast of Spain, within the framework of the DOMINO (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) project. The field campaign took place from 20 November until 9 December 2008 at the atmospheric research station "El Arenosillo" (37°5'47.76" N, 6°44'6.94" W). As the monitoring station is located at the interface between a natural park, industrial cities (Huelva, Seville) and the Atlantic Ocean a variety of physical and chemical parameters of aerosols and gas phase could be characterized in dependency on the origin of air masses. Backwards trajectories were examined and compared with local meteorology to classify characteristic air mass types for several source regions. Aerosol number and mass as well as polycyclic aromatic hydrocarbons and black carbon concentrations were measured in PM1 and size distributions were registered covering a size range from 7 nm up to 32 μm. The chemical composition of the non-refractory submicron aerosol was measured by means of an Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS). Gas phase analyzers monitored various trace gases (O3, SO2, NO, NO2, CO2) and a weather station provided meteorological parameters. Lowest average submicron particle mass and number concentrations were found in air masses arriving from the Atlantic Ocean with values around 2 μg m-3 and 1000 cm-3. These mass concentrations were about two to four times lower than the values recorded in air masses of continental and urban origins. For some species PM1-fractions in marine air were significantly larger than in air masses originating from Huelva, a closely located city with extensive industrial activities. The largest fraction of sulfate (54%) was detected in marine air masses and was to a high degree not neutralized. In addition small concentrations of methanesulfonic acid (MSA), a product of biogenic dimethyl sulfate (DMS) emissions could be identified in the particle phase. In all

Aerosol characterization over the southeastern United States using high resolution aerosol mass spectrometry: spatial and seasonal variation of aerosol composition, sources, and organic nitrates

NASA Astrophysics Data System (ADS)

Xu, L.; Suresh, S.; Guo, H.; Weber, R. J.; Ng, N. L.

2015-04-01

We deployed a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) to characterize the chemical composition of submicron non-refractory particles (NR-PM1) in the southeastern US. Measurements were performed in both rural and urban sites in the greater Atlanta area, GA and Centreville, AL for approximately one year, as part of Southeastern Center of Air Pollution and Epidemiology study (SCAPE) and Southern Oxidant and Aerosol Study (SOAS). Organic aerosol (OA) accounts for more than half of NR1 mass concentration regardless of sampling sites and seasons. Positive matrix factorization (PMF) analysis of HR-ToF-AMS measurements identified various OA sources, depending on location and season. Hydrocarbon-like OA (HOA) and cooking OA (COA) have important but not dominant contributions to total OA in urban sites. Biomass burning OA (BBOA) concentration shows a distinct seasonal variation with a larger enhancement in winter than summer. We find a good correlation between BBOA and brown carbon, indicating biomass burning is an important source for brown carbon, although an additional, unidentified brown carbon source is likely present at the rural Yorkville site. Isoprene-derived OA (Isoprene-OA) is only deconvolved in warmer months and contributes 18-36% of total OA. The presence of Isoprene-OA factor in urban sites is more likely from local production in the presence of NOx than transport from rural sites. More-oxidized and less-oxidized oxygenated organic aerosol (MO-OOA and LO-OOA, respectively) are dominant fractions (47-79%) of OA in all sites. MO-OOA correlates well with ozone in summer, but not in winter, indicating MO-OOA sources may vary with seasons. LO-OOA, which reaches a daily maximum at night, correlates better with estimated nitrate functionality from organic nitrates than total nitrates. Based on the HR-ToF-AMS measurements, we estimate that the nitrate functionality from organic nitrates

Seasonal and spatial variability of the organic matter-to-organic carbon mass ratios in Chinese urban organic aerosols and a first report of high correlations between aerosol oxalic acid and zinc

NASA Astrophysics Data System (ADS)

Xing, L.; Fu, T.-M.; Cao, J. J.; Lee, S. C.; Wang, G. H.; Ho, K. F.; Cheng, M.-C.; You, C.-F.; Wang, T. J.

2013-01-01

We calculated the organic matter to organic carbon mass ratios (OM/OC mass ratios) in PM2.5 collected from 14 Chinese cities during summer and winter of 2003 and analyzed the causes for their seasonal and spatial variability. The OM/OC mass ratios were calculated two ways. Using a mass balance method, the calculated OM/OC mass ratios averaged 1.92 ± 0.39 yr-round, with no significant seasonal or spatial variation. The second calculation was based on chemical species analyses of the organic compounds extracted from the PM2.5 samples using dichloromethane/methanol and water. The calculated OM/OC mass ratio in summer was relatively high (1.75 ± 0.13) and spatially-invariant, due to vigorous photochemistry and secondary OA production throughout the country. The calculated OM/OC mass ratio in winter (1.59 ± 0.18) was significantly lower than that in summer, with lower values in northern cities (1.51 ± 0.07) than in southern cities (1.65 ± 0.15). This likely reflects the wider usage of coal for heating purposes in northern China in winter, in contrast to the larger contributions from biofuel and biomass burning in southern China in winter. On average, organic matters constituted 36% and 34% of Chinese urban PM2.5 mass in summer and winter, respectively. We reported, for the first time, high correlations between Zn and oxalic acid in Chinese urban aerosols in summer. This is consistent with the formation of stable Zn oxalate complex in the aerosol phase previously proposed by Furukawa and Takahashi (2011). We found that many other dicarboxylic acids were also highly correlated with Zn in the summer Chinese urban aerosol samples, suggesting that they may also form stable organic complexes with Zn. Such formation may have profound implications for the atmospheric abundance and hygroscopic property of aerosol dicarboxylic acids.

Aerosol properties associated with air masses arriving into the North East Atlantic during the 2008 Mace Head EUCAARI intensive observing period: an overview

NASA Astrophysics Data System (ADS)

Dall'Osto, M.; Ceburnis, D.; Martucci, G.; Bialek, J.; Dupuy, R.; Jennings, S. G.; Berresheim, H.; Wenger, J.; Healy, R.; Facchini, M. C.; Rinaldi, M.; Giulianelli, L.; Finessi, E.; Worsnop, D.; Ehn, M.; Mikkilä, J.; Kulmala, M.; O'Dowd, C. D.

2010-09-01

As part of the EUCAARI Intensive Observing Period, a 4-week campaign to measure aerosol physical, chemical and optical properties, atmospheric structure, and cloud microphysics was conducted from mid-May to mid-June, 2008 at the Mace Head Atmospheric Research Station, located at the interface of Western Europe and the N. E. Atlantic and centered on the west Irish coastline. During the campaign, continental air masses comprising both young and aged continental plumes were encountered, along with polar, Arctic and tropical air masses. Polluted-continental aerosol concentrations were of the order of 3000 cm-3, while background marine air aerosol concentrations were between 400-600 cm-3. The highest marine air concentrations occurred in polar air masses in which a 15 nm nucleation mode, with concentration of 1100 cm-3, was observed and attributed to open ocean particle formation. Continental air submicron chemical composition (excluding refractory sea salt) was dominated by organic matter, closely followed by sulphate mass. Although the concentrations and size distribution spectral shape were almost identical for the young and aged continental cases, hygroscopic growth factors (GF) and cloud condensation nuclei (CCN) to total condensation nuclei (CN) concentration ratios were significantly less in the younger pollution plume, indicating a more oxidized organic component to the aged continental plume. The difference in chemical composition and hygroscopic growth factor appear to result in a 40-50% impact on aerosol scattering coefficients and Aerosol Optical Depth, despite almost identical aerosol microphysical properties in both cases, with the higher values been recorded for the more aged case. For the CCN/CN ratio, the highest ratios were seen in the more age plume. In marine air, sulphate mass dominated the sub-micron component, followed by water soluble organic carbon, which, in turn, was dominated by methanesulphonic acid (MSA). Sulphate concentrations were

Achievable Strength-Based Signal Detection in Quantity-Constrained PAM OOK Concentration-Encoded Molecular Communication.

PubMed

Mahfuz, Mohammad Upal

2016-10-01

In this paper, the expressions of achievable strength-based detection probabilities of concentration-encoded molecular communication (CEMC) system have been derived based on finite pulsewidth (FP) pulse-amplitude modulated (PAM) on-off keying (OOK) modulation scheme and strength threshold. An FP-PAM system is characterized by its duty cycle α that indicates the fraction of the entire symbol duration the transmitter remains on and transmits the signal. Results show that the detection performance of an FP-PAM OOK CEMC system significantly depends on the statistical distribution parameters of diffusion-based propagation noise and intersymbol interference (ISI). Analytical detection performance of an FP-PAM OOK CEMC system under ISI scenario has been explained and compared based on receiver operating characteristics (ROC) for impulse (i.e., spike)-modulated (IM) and FP-PAM CEMC schemes. It is shown that the effects of diffusion noise and ISI on ROC can be explained separately based on their communication range-dependent statistics. With full duty cycle, an FP-PAM scheme provides significantly worse performance than an IM scheme. The paper also analyzes the performance of the system when duty cycle, transmission data rate, and quantity of molecules vary.

Desert Dust Aerosol Air Mass Mapping in the Western Sahara, Using Particle Properties Derived from Space-Based Multi-Angle Imaging

NASA Technical Reports Server (NTRS)

Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Esselborn, Michael; Fiebig, Marcus; Heese, Birgit; Knippertz, Peter; Mueller, Detlef;

A new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra

NASA Astrophysics Data System (ADS)

Heringa, M. F.; Decarlo, P. F.; Chirico, R.; Tritscher, T.; Clairotte, M.; Mohr, C.; Crippa, M.; Slowik, J. G.; Pfaffenberger, L.; Dommen, J.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.

2011-10-01

Organic aerosol (OA) represents a significant and often major fraction of the non-refractory PM1 (particulate matter with an aerodynamic diameter da < 1 μm) mass. Secondary organic aerosol (SOA) is an important contributor to the OA and can be formed from biogenic and anthropogenic precursors. Here we present results from the characterization of SOA produced from the emissions of three different anthropogenic sources. SOA from a log wood burner, a Euro 2 diesel car and a two-stroke Euro 2 scooter were characterized with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and compared to SOA from α-pinene. The emissions were sampled from the chimney/tailpipe by a heated inlet system and filtered before injection into a smog chamber. The gas phase emissions were irradiated by xenon arc lamps to initiate photo-chemistry which led to nucleation and subsequent particle growth by SOA production. Duplicate experiments were performed for each SOA type, with the averaged organic mass spectra in the m/z range 12-250 showing Pearson's r values >0.94 for the correlations between the different SOA types after 5 h of aging. High-resolution mass spectra (HR-MS) showed that the dominant peaks in the MS, m/z 43 and 44, are dominated by the oxygenated ions C2H3O+ and CO2+, respectively, similarly to the relatively fresh semi-volatile oxidized OA (SV-OOA) observed in the ambient aerosol. The atomic O : C ratios were found to be in the range of 0.25-0.55 with no major increase during the first 5 h of aging. On average, the diesel SOA showed the lowest O : C ratio followed by SOA from wood burning, α-pinene and the scooter emissions. Grouping the fragment ions based on their carbon number revealed that the SOA source with the highest O : C ratio had the largest fraction of small ions. Fragment ions containing up to 3 carbon atoms accounted for 66%, 68%, 72% and 76% of the organic spectrum of the SOA produced by the diesel car, wood burner, α-pinene and

Urban increments of gaseous and aerosol pollutants and their sources using mobile aerosol mass spectrometry measurements

NASA Astrophysics Data System (ADS)

Elser, Miriam; Bozzetti, Carlo; El-Haddad, Imad; Maasikmets, Marek; Teinemaa, Erik; Richter, Rene; Wolf, Robert; Slowik, Jay G.; Baltensperger, Urs; Prévôt, André S. H.

2016-06-01

Air pollution is one of the main environmental concerns in urban areas, where anthropogenic emissions strongly affect air quality. This work presents the first spatially resolved detailed characterization of PM2.5 (particulate matter with aerodynamic equivalent diameter daero ≤ 2.5 µm) in two major Estonian cities, Tallinn and Tartu. The measurements were performed in March 2014 using a mobile platform. In both cities, the non-refractory (NR)-PM2.5 was characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) using a recently developed lens which increases the transmission of super-micron particles. Equivalent black carbon (eBC) and several trace gases including carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) were also measured. The chemical composition of PM2.5 was found to be very similar in the two cities. Organic aerosol (OA) constituted the largest fraction, explaining on average about 52 to 60 % of the PM2.5 mass. Four sources of OA were identified using positive matrix factorization (PMF): hydrocarbon-like OA (HOA, from traffic emissions), biomass burning OA (BBOA, from biomass combustion), residential influenced OA (RIOA, probably mostly from cooking processes with possible contributions from waste and coal burning), and oxygenated OA (OOA, related to secondary aerosol formation). OOA was the major OA source during nighttime, explaining on average half of the OA mass, while during daytime mobile measurements the OA was affected by point sources and dominated by the primary fraction. A strong increase in the secondary organic and inorganic components was observed during periods with transport of air masses from northern Germany, while the primary local emissions accumulated during periods with temperature inversions. Mobile measurements offered the identification of different source regions within the urban areas and the assessment of the extent to which pollutants concentrations exceeded regional background

Response of an aerosol mass spectrometer to organonitrates and organosulfates and implications for atmospheric chemistry.

PubMed

Farmer, D K; Matsunaga, A; Docherty, K S; Surratt, J D; Seinfeld, J H; Ziemann, P J; Jimenez, J L

2010-04-13

Organonitrates (ON) are important products of gas-phase oxidation of volatile organic compounds in the troposphere; some models predict, and laboratory studies show, the formation of large, multifunctional ON with vapor pressures low enough to partition to the particle phase. Organosulfates (OS) have also been recently detected in secondary organic aerosol. Despite their potential importance, ON and OS remain a nearly unexplored aspect of atmospheric chemistry because few studies have quantified particulate ON or OS in ambient air. We report the response of a high-resolution time-of-flight aerosol mass spectrometer (AMS) to aerosol ON and OS standards and mixtures. We quantify the potentially substantial underestimation of organic aerosol O/C, commonly used as a metric for aging, and N/C. Most of the ON-nitrogen appears as NO(x)+ ions in the AMS, which are typically dominated by inorganic nitrate. Minor organonitrogen ions are observed although their identity and intensity vary between standards. We evaluate the potential for using NO(x)+ fragment ratios, organonitrogen ions, HNO(3)+ ions, the ammonium balance of the nominally inorganic ions, and comparison to ion-chromatography instruments to constrain the concentrations of ON for ambient datasets, and apply these techniques to a field study in Riverside, CA. OS manifests as separate organic and sulfate components in the AMS with minimal organosulfur fragments and little difference in fragmentation from inorganic sulfate. The low thermal stability of ON and OS likely causes similar detection difficulties for other aerosol mass spectrometers using vaporization and/or ionization techniques with similar or larger energy, which has likely led to an underappreciation of these species.

PAM-4 Signaling over VCSELs with 0.13µm CMOS Chip Technology

NASA Astrophysics Data System (ADS)

Cunningham, J. E.; Beckman, D.; Zheng, Xuezhe; Huang, Dawei; Sze, T.; Krishnamoorthy, A. V.

2006-12-01

We present results for VCSEL based links operating PAM-4 signaling using a commercial 0.13µm CMOS technology. We perform a complete link analysis of the Bit Error Rate, Q factor, random and deterministic jitter by measuring waterfall curves versus margins in time and amplitude. We demonstrate that VCSEL based PAM 4 can match or even improve performance over binary signaling under conditions of a bandwidth limited, 100meter multi-mode optical link at 5Gbps. We present the first sensitivity measurements for optical PAM-4 and compare it with binary signaling. Measured benefits are reconciled with information theory predictions.

PAM-4 Signaling over VCSELs with 0.13microm CMOS Chip Technology.

PubMed

Cunningham, J E; Beckman, D; Zheng, Xuezhe; Huang, Dawei; Sze, T; Krishnamoorthy, A V

2006-12-11

We present results for VCSEL based links operating PAM-4 signaling using a commercial 0.13microm CMOS technology. We perform a complete link analysis of the Bit Error Rate, Q factor, random and deterministic jitter by measuring waterfall curves versus margins in time and amplitude. We demonstrate that VCSEL based PAM-4 can match or even improve performance over binary signaling under conditions of a bandwidth limited, 100meter multi-mode optical link at 5Gbps. We present the first sensitivity measurements for optical PAM-4 and compare it with binary signaling. Measured benefits are reconciled with information theory predictions.

[Cryotherapy is useful and safe in the prevention of oral mucositis after high-dose melphalan (L-PAM)].

PubMed

Inagaki, Noriko; Ohue, Yukiko; Shigeta, Hiroe; Tasaka, Taizo

2006-11-01

We prospectively assessed the effectiveness of cryotherapy after high-dose L-PAM to prevent oral mucositis. Cryotherapy with ice tips was commenced 15 minutes before L-PAM administration, and continued until the end of administration. Twenty-six patients were enrolled in this study. Thirteen patients with myeloma were treated with 200 mg/m2 L-PAM followed by autologous peripheral blood stem cell transplantation, and 13 patients (4 AML, 4 MDS, 2 ALL, 2 lymphoma and 1 CML) were treated with 140 mg/m2 L-PAM followed by allogeneic stem cell transplantation. Grade 1 mucositis occurred in four of 13 patients (31%) with 200 mg/m2 L-PAM, and 2 of 13 patients (16%) with 140 mg/m2 L-PAM. Only one patient had grade 2 mucositis, and no grade 3 mucositis were observed. The procedure was well tolerated in all patients. These data suggest that cryotherapy is effective to minimize L-PAM-induced oral mucositis.

Molecular Characterization of Organosulfates in Urban Aerosols during the Spring Festival by FT-ICR Mass Spectrometry

NASA Astrophysics Data System (ADS)

Xie, Q.; Fu, P.

2017-12-01

Aerosol particles collected at daytime and nighttime in Beijing during the spring festival, including the episodes of various gradient level pollution and short-term pollution raised by fireworks, were analyzed using 15T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS). Organosulfates (OSs), tracers for secondary organic aerosol formation, were identified through accurate mass measurements. Both the total number and the arbitrary abundance of OSs were consistent with the total OC concentrations of the aerosol samples. Nitrooxy-organosulfates were more abundant in the nighttime than those in the daytime due to high NOX concentrations at night. Although all subgroups OSs increased with the deterioration of air quality, especially for the relative abundance of aromatic OSs with high double bond equivalents, the percentage contributions of aliphatic OSs with low degree of unsaturation decreased. It was worth to note that aliphatic OSs with a wide range in carbon-chain length of C6-40 were identified in this study. The candidates for their potential precursors were alkanes and fatty acids. Moreover, a large number of aromatic OSs, about two thirds of OSs, were detected. The rapid formation of these compounds in New Year's Eve with plentiful aromatics from firework burning suggests that they may be derived from PAHs. The high carbon and oxygen contents of OSs may indicate the presence of dimmers, even polymers. Our results support the important contribution of anthropogenic precursors to OSs in ambient aerosols on the basis of aromatic and aliphatic OSs, which may have a significant impact on the hygroscopic properties of ambient aerosol particles.

Cluster analysis of the organic peaks in bulk mass spectra obtained during the 2002 New England Air Quality Study with an Aerodyne aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

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

2006-06-01

We applied hierarchical cluster analysis to an Aerodyne aerosol mass spectrometer (AMS) bulk mass spectral dataset collected aboard the NOAA research vessel Ronald H. Brown during the 2002 New England Air Quality Study off the east coast of the United States. Emphasizing the organic peaks, the cluster analysis yielded a series of categories that are distinguishable with respect to their mass spectra and their occurrence as a function of time. The differences between the categories mainly arise from relative intensity changes rather than from the presence or absence of specific peaks. The most frequent category exhibits a strong signal at m/z 44 and represents oxidized organic matter most probably originating from both, anthropogenic as well as biogenic sources. On the basis of spectral and trace gas correlations, the second most common category with strong signals at m/z 29, 43, and 44 contains contributions from isoprene oxidation products. The third through the fifth most common categories have peak patterns characteristic of monoterpene oxidation products and were most frequently observed when air masses from monoterpene rich regions were sampled. Taken together, the second through the fifth most common categories represent as much as 5 µg/m3 organic aerosol mass - 17% of the total organic mass - that can be attributed to biogenic sources. These numbers have to be viewed as lower limits since the most common category was attributed to anthropogenic sources for this calculation. The cluster analysis was also very effective in identifying a few contaminated mass spectra that were not removed during pre-processing. This study demonstrates that hierarchical clustering is a useful tool to analyze the complex patterns of the organic peaks in bulk aerosol mass spectra from a field study.

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

Aerosol Optical Properties Measured Onboard the Ronald H. Brown During ACE Asia as a Function of Aerosol Chemical Composition and Source Region

NASA Technical Reports Server (NTRS)

Quinn, P. K.; Coffman, D. J.; Bates, T. S.; Welton, E. J.; Covert, D. S.; Miller, T. L.; Johnson, J. E.; Maria, S.; Russell, L.; Arimoto, R.

2004-01-01

During the ACE Asia intensive field campaign conducted in the spring of 2001 aerosol properties were measured onboard the R/V Ronald H. Brown to study the effects of the Asian aerosol on atmospheric chemistry and climate in downwind regions. Aerosol properties measured in the marine boundary layer included chemical composition; number size distribution; and light scattering, hemispheric backscattering, and absorption coefficients. In addition, optical depth and vertical profiles of aerosol 180 deg backscatter were measured. Aerosol within the ACE Asia study region was found to be a complex mixture resulting from marine, pollution, volcanic, and dust sources. Presented here as a function of air mass source region are the mass fractions of the dominant aerosol chemical components, the fraction of the scattering measured at the surface due to each component, mass scattering efficiencies of the individual components, aerosol scattering and absorption coefficients, single scattering albedo, Angstrom exponents, optical depth, and vertical profiles of aerosol extinction. All results except aerosol optical depth and the vertical profiles of aerosol extinction are reported at a relative humidity of 55 +/- 5%. An over-determined data set was collected so that measured and calculated aerosol properties could be compared, internal consistency in the data set could be assessed, and sources of uncertainty could be identified. By taking into account non-sphericity of the dust aerosol, calculated and measured aerosol mass and scattering coefficients agreed within overall experimental uncertainties. Differences between measured and calculated aerosol absorption coefficients were not within reasonable uncertainty limits, however, and may indicate the inability of Mie theory and the assumption of internally mixed homogeneous spheres to predict absorption by the ACE Asia aerosol. Mass scattering efficiencies of non-sea salt sulfate aerosol, sea salt, submicron particulate organic

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Microphysical processing of aerosol particles in orographic clouds

NASA Astrophysics Data System (ADS)

Pousse-Nottelmann, S.; Zubler, E. M.; Lohmann, U.

2015-01-01

An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented in the regional weather forecast and climate model COSMO. The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snow flakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snow flakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. However, the processes not only impact the total aerosol number and mass, but also the shape of the aerosol size distributions by enhancing the internally mixed/soluble accumulation mode and generating coarse mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases the cloud droplet number concentration with possible implications for the ice

Microphysical processing of aerosol particles in orographic clouds

NASA Astrophysics Data System (ADS)

Pousse-Nottelmann, S.; Zubler, E. M.; Lohmann, U.

2015-08-01

An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented into COSMO-Model, the regional weather forecast and climate model of the Consortium for Small-scale Modeling (COSMO). The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed us to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen (WBF) process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snowflakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snowflakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. Thereby, the processes impact the total aerosol number and mass and additionally alter the shape of the aerosol size distributions by enhancing the internally mixed/soluble Aitken and accumulation mode and generating coarse-mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases

New approaches for the chemical and physical characterization of aerosols using a single particle mass spectrometry based technique

NASA Astrophysics Data System (ADS)

Spencer, Matthew Todd

Aerosols affect the lives of people every day. They can decrease visibility, alter cloud formation and cloud lifetimes, change the energy balance of the earth and are implicated in causing numerous health problems. Measuring the physical and chemical properties of aerosols is essential to understand and mitigate any negative impacts that aerosols might have on climate and human health. Aerosol time-of-flight mass spectrometry (ATOFMS) is a technique that measures the size and chemical composition of individual particles in real time. The goal of this dissertation is to develop new and useful approaches for measuring the physical and/or chemical properties of particles using ATOFMS. This has been accomplished using laboratory experiments, ambient field measurements and sometimes comparisons between them. A comparison of mass spectra generated from petrochemical particles was made to light duty vehicle (LDV) and heavy duty diesel vehicle (HDDV) particle mass spectra. This comparison has given us new insight into how to differentiate between particles from these two sources. A method for coating elemental carbon (EC) particles with organic carbon (OC) was used to generate a calibration curve for quantifying the fraction of organic carbon and elemental carbon on particles using ATOFMS. This work demonstrates that it is possible to obtain quantitative chemical information with regards to EC and OC using ATOFMS. The relationship between electrical mobility diameter and aerodynamic diameter is used to develop a tandem differential mobility analyzer-ATOFMS technique to measure the effective density, size and chemical composition of particles. The method is applied in the field and gives new insight into the physical/chemical properties of particles. The size resolved chemical composition of aerosols was measured in the Indian Ocean during the monsoonal transition period. This field work shows that a significant fraction of aerosol transported from India was from biomass

PAM-4 signal delivery in one radio-over-fiber system

NASA Astrophysics Data System (ADS)

Wang, Hada; Zhou, Wen; Yu, Jianjun

2017-10-01

We propose and experimentally demonstrate four-level pulse-amplitude-modulation (PAM-4) signal delivery in a radio-over-fiber system for the first time. Over 8-Gbit/s PAM-4 signals have been transmitted over 20-km single-mode fiber-28 and 1-m wireless distance. The signal after transmission is detected directly by an envelope detector at the receiver side. The maximal bit rate could be increased if the bandpass amplifier and envelope detector have more bandwidth.

Aerosol properties associated with air masses arriving into the North East Atlantic during the 2008 Mace Head EUCAARI intensive observing period: an overview

NASA Astrophysics Data System (ADS)

Dall'Osto, M.; Ceburnis, D.; Martucci, G.; Bialek, J.; Dupuy, R.; Jennings, S. G.; Berresheim, H.; Wenger, J. C.; Sodeau, J. R.; Healy, R. M.; Facchini, M. C.; Rinaldi, M.; Giulianelli, L.; Finessi, E.; Worsnop, D.; O'Dowd, C. D.

2009-12-01

As part of the EUCAARI Intensive Observing Period, a 4-week campaign to measure aerosol physical, chemical and optical properties, atmospheric structure, and cloud microphysics was conducted from mid-May to mid-June 2008 at the Mace Head Atmospheric Research Station, located at the interface of Western Europe and the NE Atlantic and centered on the west Irish coastline. During the campaign, continental air masses comprising both young and aged continental plumes were encountered, along with polar, Arctic and tropical air masses. Polluted-continental aerosol concentrations were of the order of 3000 cm-3, while background marine air aerosol concentrations were between 400-600 cm-3. The highest marine air concentrations occurred in polar air masses in which a 15 nm nucleation mode, with concentration of 1100 cm-3, was observed and attributed to open ocean particle formation. Black carbon concentrations in polluted air were between 300-400 ng m-3, and in clean marine air were less than 50 ng m-3. Continental air submicron chemical composition (excluding refractory sea salt) was dominated by organic matter, closely followed by sulphate mass. Although the concentrations and size distribution spectral shape were almost identical for the young and aged continental cases, hygroscopic growth factors (GF) and cloud condensation nuclei (CCN) to total condensation nuclei (CN) concentration ratios were significantly less in the younger pollution plume, indicating a more oxidized organic component to the aged continental plume. The difference in chemical composition and hygroscopic growth factor appear to result in a 40-50% impact on aerosol scattering coefficients and Aerosol Optical Depth, despite almost identical aerosol microphysical properties in both cases, with the higher values been recorded for the more aged case. For the CCN/CN ratio, the highest ratios were seen in the more age plume. In marine air, sulphate mass dominated the sub-micron component, followed by water

Highly time-resolved chemical characterization of atmospheric submicron particles during 2008 Beijing Olympic Games using an Aerodyne High-Resolution Aerosol Mass Spectrometer

NASA Astrophysics Data System (ADS)

Huang, X.-F.; He, L.-Y.; Hu, M.; Canagaratna, M. R.; Sun, Y.; Zhang, Q.; Zhu, T.; Xue, L.; Zeng, L.-W.; Liu, X.-G.; Zhang, Y.-H.; Jayne, J. T.; Ng, N. L.; Worsnop, D. R.

2010-09-01

As part of Campaigns of Air Quality Research in Beijing and Surrounding Region-2008 (CAREBeijing-2008), an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed in urban Beijing to characterize submicron aerosol particles during the time of 2008 Beijing Olympic Games and Paralympic Games (24 July to 20 September 2008). The campaign mean PM1 mass concentration was 63.1 ± 39.8 μg m-3; the mean composition consisted of organics (37.9%), sulfate (26.7%), ammonium (15.9%), nitrate (15.8%), black carbon (3.1%), and chloride (0.87%). The average size distributions of the species (except BC) were all dominated by an accumulation mode peaking at about 600 nm in vacuum aerodynamic diameter, and organics was characterized by an additional smaller mode extending below 100 nm. Positive Matrix Factorization (PMF) analysis of the high resolution organic mass spectral dataset differentiated the organic aerosol into four components, i.e., hydrocarbon-like (HOA), cooking-related (COA), and two oxygenated organic aerosols (OOA-1 and OOA-2), which on average accounted for 18.1, 24.4, 33.7 and 23.7% of the total organic mass, respectively. The HOA was identified to be closely associated with primary combustion sources, while the COA mass spectrum and diurnal pattern showed similar characteristics to that measured for cooking emissions. The OOA components correspond to aged secondary organic aerosol. Although the two OOA components have similar elemental (O/C, H/C) compositions, they display differences in mass spectra and time series which appear to correlate with the different source regions sampled during the campaign. Back trajectory clustering analysis indicated that the southerly air flows were associated with the highest PM1 pollution during the campaign. Aerosol particles in southern airmasses were especially rich in inorganic and oxidized organic species. Aerosol particles in northern airmasses contained a large fraction of primary HOA

Spatial and temporal variations of aerosols around Beijing in summer 2006: 2. Local and column aerosol optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsui, Hitoshi; Koike, Makoto; Kondo, Yutaka

Weather Research and Forecasting (WRF)-chem model calculations were conducted to study aerosol optical properties around Beijing, China, during the Campaign of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006) period. In this paper, we interpret aerosol optical properties in terms of aerosol mass concentrations and their chemical compositions by linking model calculations with measurements. In general, model calculations reproduced observed features of spatial and temporal variations of various surface and column aerosol optical parameters in and around Beijing. Spatial and temporal variations of aerosol absorption, scattering, and extinction coefficient corresponded well to those of elemental carbon (primary aerosol),more » sulfate (secondary aerosol), and the total aerosol mass concentration, respectively. These results show that spatial and temporal variations of the absorption coefficient are controlled by local emissions (within 100 km around Beijing during the preceding 24 h), while those of the scattering coefficient are controlled by regional-scale emissions (within 500 km around Beijing during the preceding 3 days) under synoptic-scale meteorological conditions, as discussed in our previous study of aerosol mass concentration. Vertical profiles of aerosol extinction revealed that the contribution of secondary aerosols and their water uptake increased with altitude within the planetary boundary layer, leading to a considerable increase in column aerosol optical depth (AOD) around Beijing. These effects are the main factors causing differences in regional and temporal variations between particulate matter (PM) mass concentration at the surface and column AOD over a wide region in the northern part of the Great North China Plain.« less

Investigation of shortcomings in simulated aerosol vertical profiles

NASA Astrophysics Data System (ADS)

Park, S.; Allen, R.

2017-12-01

The vertical distribution of aerosols is one important factor for aerosol radiative forcing. Previous studies show that climate models poorly reproduce the aerosol vertical profile, with too much aerosol aloft in the upper troposphere. This bias may be related to several factors, including excessive convective mass flux and wet removal. In this study, we evaluate the aerosol vertical profile from several Coupled Model Intercomparison Project 5 (CMIP5) models, as well as the Community Atmosphere Model 5 (CAM5), relative to the Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observation (CALIPSO). The results show that all models significantly underestimate extinction coefficient in the lower troposphere, while overestimating extinction coefficient in the upper troposphere. In addition, the majority of models indicate a land-ocean dependence in the relationship between aerosol extinction coefficient in the upper troposphere and convective mass flux. Over the continents, more convective mass flux is related to more aerosol aloft; over the ocean, more convective mass flux is associated with less aerosol in upper troposphere. Sensitivity experiments are conducted to investigate the role that convection and wet deposition have in contributing to the deficient simulation of the vertical aerosol profile, including the land-ocean dependence.

Aerosol Constraints on the Atmosphere of the Hot Saturn-mass Planet WASP-49b

NASA Astrophysics Data System (ADS)

Cubillos, Patricio E.; Fossati, Luca; Erkaev, Nikolai V.; Malik, Matej; Tokano, Tetsuya; Lendl, Monika; Johnstone, Colin P.; Lammer, Helmut; Wyttenbach, Aurélien

2017-11-01

The strong, nearly wavelength-independent absorption cross section of aerosols produces featureless exoplanet transmission spectra, limiting our ability to characterize their atmospheres. Here, we show that even in the presence of featureless spectra, we can still characterize certain atmospheric properties. Specifically, we constrain the upper and lower pressure boundaries of aerosol layers, and present plausible composition candidates. We study the case of the bloated Saturn-mass planet WASP-49 b, where near-infrared observations reveal a flat transmission spectrum between 0.7 and 1.0 μm. First, we use a hydrodynamic upper-atmosphere code to estimate the pressure reached by the ionizing stellar high-energy photons at {10}-8 bar, setting the upper pressure boundary where aerosols could exist. Then, we combine HELIOS and Pyrat Bay radiative-transfer models to constrain the temperature and photospheric pressure of atmospheric aerosols, in a Bayesian framework. For WASP-49 b, we constrain the transmission photosphere (hence, the aerosol deck boundaries) to pressures above {10}-5 bar (100× solar metallicity), {10}-4 bar (solar), and {10}-3 bar (0.1× solar) as the lower boundary, and below {10}-7 bar as the upper boundary. Lastly, we compare condensation curves of aerosol compounds with the planet’s pressure-temperature profile to identify plausible condensates responsible for the absorption. Under these circumstances, we find these candidates: {{Na}}2{{S}} (at 100× solar metallicity); Cr and MnS (at solar and 0.1× solar) and forsterite, enstatite, and alabandite (at 0.1× solar).

Evaluations of tropospheric aerosol properties simulated by the community earth system model with a sectional aerosol microphysics scheme

PubMed Central

Toon, Owen B.; Bardeen, Charles G.; Mills, Michael J.; Fan, Tianyi; English, Jason M.; Neely, Ryan R.

2015-01-01

Abstract A sectional aerosol model (CARMA) has been developed and coupled with the Community Earth System Model (CESM1). Aerosol microphysics, radiative properties, and interactions with clouds are simulated in the size‐resolving model. The model described here uses 20 particle size bins for each aerosol component including freshly nucleated sulfate particles, as well as mixed particles containing sulfate, primary organics, black carbon, dust, and sea salt. The model also includes five types of bulk secondary organic aerosols with four volatility bins. The overall cost of CESM1‐CARMA is approximately ∼2.6 times as much computer time as the standard three‐mode aerosol model in CESM1 (CESM1‐MAM3) and twice as much computer time as the seven‐mode aerosol model in CESM1 (CESM1‐MAM7) using similar gas phase chemistry codes. Aerosol spatial‐temporal distributions are simulated and compared with a large set of observations from satellites, ground‐based measurements, and airborne field campaigns. Simulated annual average aerosol optical depths are lower than MODIS/MISR satellite observations and AERONET observations by ∼32%. This difference is within the uncertainty of the satellite observations. CESM1/CARMA reproduces sulfate aerosol mass within 8%, organic aerosol mass within 20%, and black carbon aerosol mass within 50% compared with a multiyear average of the IMPROVE/EPA data over United States, but differences vary considerably at individual locations. Other data sets show similar levels of comparison with model simulations. The model suggests that in addition to sulfate, organic aerosols also significantly contribute to aerosol mass in the tropical UTLS, which is consistent with limited data. PMID:27668039

Chemical composition of Titan's aerosols analogues characterized with a systematic pyrolysis-gas chromatography-mass spectrometry characterization

NASA Astrophysics Data System (ADS)

Szopa, Cyril; Raulin, Francois; Coll, Patrice; Cabane, Michel; GCMS Team

2014-05-01

The in situ chemical characterization of Titan's atmosphere was achieved in 2005 with two instruments present onboard the Huygens atmospheric probe : the Aerosol Collector and Pyrolyzer (ACP) devoted to collect and pyrolyse Titan's aerosols ; the Gas Chromatograph-Mass Spectrometer (GCMS) experiment devoted to analyze gases collected in the atmosphere or coming from the aerosols pyrolysis. The GCMS was developed by Hasso Niemann in the filiation of the quadrupole mass spectrometers he built for several former space missions. The main objectives were to : determine the concentration profile of the most abundant chemical species; seek for minor atmospheric organic species not detected with remote observations ; give a first view of the organic aerosols structure; characterize the condensed volatiles present at the surface (e.g. lakes) in case of survival of the probe to the landing impact. Taking into account for the potential complexity of the gaseous samples to be analyzed, it was decided to couple to the MS analyzer a gas chromatograph capable to separate volatile species from light inorganic molecules and noble gases, to organic compounds including aromatics. This was the first GCMS analyzer that worked in an extraterrestrial environment since the Viking missions on Mars. Even if the GCMS coupling mode did not provide any result of interest, it has been demonstrated to be functional during the Huygens descent. But, the direct MS analysis of the atmosphere, and the pyrolysis-MS analysis of aerosols allowed to make great discoveries which are still of primary importance to describe the Titan's lower atmosphere composition. This contribution aims at presenting this instrument that worked in the Titan's atmosphere, and summarizing the most important discoveries it allowed.

Characterizing Organic Aerosol Processes and Climatically Relevant Properties via Advanced and Integrated Analyses of Aerosol Mass Spectrometry Datasets from DOE Campaigns and ACRF Measurements. Final report for DE-SC0007178

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Qi

Organic aerosols (OA) are an important but poorly characterized component of the earth’s climate system. Enormous complexities commonly associated with OA composition and life cycle processes have significantly complicated the simulation and quantification of aerosol effects. To unravel these complexities and improve understanding of the properties, sources, formation, evolution processes, and radiative properties of atmospheric OA, we propose to perform advanced and integrated analyses of multiple DOE aerosol mass spectrometry datasets, including two high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) datasets from intensive field campaigns on the aerosol life cycle and the Aerosol Chemical Speciation Monitor (ACSM) datasets from long-term routinemore » measurement programs at ACRF sites. In this project, we will focus on 1) characterizing the chemical (i.e., composition, organic elemental ratios), physical (i.e., size distribution and volatility), and radiative (i.e., sub- and super-saturated growth) properties of organic aerosols, 2) examining the correlations of these properties with different source and process regimes (e.g., primary, secondary, urban, biogenic, biomass burning, marine, or mixtures), 3) quantifying the evolutions of these properties as a function of photochemical processing, 4) identifying and characterizing special cases for important processes such as SOA formation and new particle formation and growth, and 5) correlating size-resolved aerosol chemistry with measurements of radiative properties of aerosols to determine the climatically relevant properties of OA and characterize the relationship between these properties and processes of atmospheric aerosol organics. Our primary goal is to improve a process-level understanding of the life cycle of organic aerosols in the Earth’s atmosphere. We will also aim at bridging between observations and models via synthesizing and translating the results and insights generated from

High-Resolution Electrospray Ionization Mass Spectrometry Analysis of Water- Soluble Organic Aerosols Collected with a Particle into Liquid Sampler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bateman, Adam P.; Nizkorodov, Serguei; Laskin, Julia

2010-10-01

This work demonstrates the utility of a particle-into-liquid sampler (PILS) a technique traditionally used for identification of inorganic ions present in ambient or laboratory aerosols for the analysis of water soluble organic aerosol (OA) using high resolution electrospray ionization mass spectrometry (HR ESI-MS). Secondary organic aerosol (SOA) was produced from 0.5 ppm mixing ratios of limonene and ozone in a 5 m3 Teflon chamber. SOA was collected simultaneously using a traditional filter sampler and a PILS. The filter samples were later extracted with either water or acetonitrile, while the aqueous PILS samples were analyzed directly. In terms of peak intensities,more » types of detectable compounds, average O:C ratios, and organic mass to organic carbon ratios, the resulting high resolution mass spectra were essentially identical for the PILS and filter based samples. SOA compounds extracted from both filter/acetonitrile extraction and PILS/water extraction accounted for >95% of the total ion current in ESI mass spectra. This similarity was attributed to high solubility of limonene SOA in water. In contrast, significant differences in detected ions and peak abundances were observed for pine needle biomass burning organic aerosol (BBOA) collected with PILS and filter sampling. The water soluble fraction of BBOA is considerably smaller than for SOA, and a number of unique peaks were detectable only by the filter/acetonitrile method. The combination of PILS collection with HR-ESI-MS analysis offers a new approach for molecular analysis of the water-soluble organic fraction in biogenic SOA, aged photochemical smog, and BBOA.« less

Aerosol characterization over the southeastern United States using high-resolution aerosol mass spectrometry: spatial and seasonal variation of aerosol composition and sources with a focus on organic nitrates

NASA Astrophysics Data System (ADS)

Xu, L.; Suresh, S.; Guo, H.; Weber, R. J.; Ng, N. L.

2015-07-01

We deployed a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) to characterize the chemical composition of submicron non-refractory particulate matter (NR-PM1) in the southeastern USA. Measurements were performed in both rural and urban sites in the greater Atlanta area, Georgia (GA), and Centreville, Alabama (AL), for approximately 1 year as part of Southeastern Center for Air Pollution and Epidemiology study (SCAPE) and Southern Oxidant and Aerosol Study (SOAS). Organic aerosol (OA) accounts for more than half of NR-PM1 mass concentration regardless of sampling sites and seasons. Positive matrix factorization (PMF) analysis of HR-ToF-AMS measurements identified various OA sources, depending on location and season. Hydrocarbon-like OA (HOA) and cooking OA (COA) have important, but not dominant, contributions to total OA in urban sites (i.e., 21-38 % of total OA depending on site and season). Biomass burning OA (BBOA) concentration shows a distinct seasonal variation with a larger enhancement in winter than summer. We find a good correlation between BBOA and brown carbon, indicating biomass burning is an important source for brown carbon, although an additional, unidentified brown carbon source is likely present at the rural Yorkville site. Isoprene-derived OA factor (isoprene-OA) is only deconvolved in warmer months and contributes 18-36 % of total OA. The presence of isoprene-OA factor in urban sites is more likely from local production in the presence of NOx than transport from rural sites. More-oxidized and less-oxidized oxygenated organic aerosol (MO-OOA and LO-OOA, respectively) are dominant fractions (47-79 %) of OA in all sites. MO-OOA correlates well with ozone in summer but not in winter, indicating MO-OOA sources may vary with seasons. LO-OOA, which reaches a daily maximum at night, correlates better with estimated nitrate functionality from organic nitrates than total nitrates. Based

Aerosol Chemical Composition and its Effects on Cloud-Aerosol Interactions during the 2007 CHAPS Experiment

NASA Astrophysics Data System (ADS)

Lee, Y.; Alexander, L.; Newburn, M.; Jayne, J.; Hubbe, J.; Springston, S.; Senum, G.; Andrews, B.; Ogren, J.; Kleinman, L.; Daum, P.; Berg, L.; Berkowitz, C.

2007-12-01

Chemical composition of submicron aerosol particles was determined using an Aerodyne Time-of-Flight Aerosol Mass Spectrometer (AMS) outfitted on the DOE G-1 aircraft during the Cumulus Humilis Aerosol Processing Study (CHAPS) conducted in Oklahoma City area in June 2007. The primary objective of CHAPS was to investigate the effects of urban emissions on cloud aerosol interactions as a function of processing of the emissions. Aerosol composition was typically determined at three different altitudes: below, in, and above cloud, in both upwind and downwind regions of the urban area. Aerosols were sampled from an isokinetic inlet with an upper size cut-off of ~1.5 micrometer. During cloud passages, the AMS also sampled particles that were dried from cloud droplets collected using a counter-flow virtual impactor (CVI) sampler. The aerosol mass concentrations were typically below 10 microgram per cubic meter, and were dominated by organics and sulfate. Ammonium was often less than required for complete neutralization of sulfate. Aerosol nitrate levels were very low. We noted that nitrate levels were significantly enhanced in cloud droplets compared to aerosols, most likely resulting from dissolution of gaseous nitric acid. Organic to sulfate ratios appeared to be lower in cloud droplets than in aerosols, suggesting cloud condensation nuclei properties of aerosol particles might be affected by loading and nature of the organic components in aerosols. In-cloud formation of sulfate was considered unimportant because of the very low SO2 concentration in the region. A detailed examination of the sources of the aerosol organic components (based on hydrocarbons determined using a proton transfer reaction mass spectrometer) and their effects on cloud formation as a function of atmospheric processing (based on the degree of oxidation of the organic components) will be presented.

Characterization of a real-time tracer for isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

NASA Astrophysics Data System (ADS)

Hu, W. W.; Campuzano-Jost, P.; Palm, B. B.; Day, D. A.; Ortega, A. M.; Hayes, P. L.; Krechmer, J. E.; Chen, Q.; Kuwata, M.; Liu, Y. J.; de Sá, S. S.; McKinney, K.; Martin, S. T.; Hu, M.; Budisulistiorini, S. H.; Riva, M.; Surratt, J. D.; St. Clair, J. M.; Isaacman-Van Wertz, G.; Yee, L. D.; Goldstein, A. H.; Carbone, S.; Brito, J.; Artaxo, P.; de Gouw, J. A.; Koss, A.; Wisthaler, A.; Mikoviny, T.; Karl, T.; Kaser, L.; Jud, W.; Hansel, A.; Docherty, K. S.; Alexander, M. L.; Robinson, N. H.; Coe, H.; Allan, J. D.; Canagaratna, M. R.; Paulot, F.; Jimenez, J. L.

2015-10-01

Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene oxidation pathways, was quantified by applying positive matrix factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of organic aerosol (OA) in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the Southern Oxidant and Aerosol Study (SOAS), 78 % of PMF-resolved IEPOX-SOA is accounted by the measured IEPOX-SOA molecular tracers (2-methyltetrols, C5-Triols, and IEPOX-derived organosulfate and its dimers), making it the highest level of molecular identification of an ambient SOA component to our knowledge. An enhanced signal at C5H6O+ (m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine fC5H6O (fC5H6O= C5H6O+/OA) across multiple field, chamber, and source data sets. A background of ~ 1.7 ± 0.1 ‰ (‰ = parts per thousand) is observed in studies strongly influenced by urban, biomass-burning, and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.6 ‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0 ‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7 ‰), which leaves some room to separate both contributions to OA. Locations strongly influenced by isoprene emissions under low-NO levels had higher fC5H6O (~ 6.5 ± 2.2 ‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. fC5H6O in IEPOX-SOA is always elevated (12-40 ‰) but varies substantially between locations, which is shown to reflect

Characterization of a real-time tracer for isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, W. W.; Campuzano-Jost, P.; Palm, B. B.

Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene oxidation pathways, was quantified by applying positive matrix factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of organic aerosol (OA) in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the Southern Oxidant and Aerosol Study (SOAS), 78 % of PMF-resolved IEPOX-SOA is accountedmore » by the measured IEPOX-SOA molecular tracers (2-methyltetrols, C5-Triols, and IEPOX-derived organosulfate and its dimers), making it the highest level of molecular identification of an ambient SOA component to our knowledge. An enhanced signal at C 5H 6O + ( m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine f C5H6O ( f C5H6O= C 5H 6O +/OA) across multiple field, chamber, and source data sets. A background of ~ 1.7 ± 0.1 ‰ (‰ = parts per thousand) is observed in studies strongly influenced by urban, biomass-burning, and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.6 ‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0 ‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7 ‰), which leaves some room to separate both contributions to OA. Locations strongly influenced by isoprene emissions under low-NO levels had higher f C5H6O (~ 6.5 ± 2.2 ‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. f C5H6O in IEPOX-SOA is always elevated (12–40 ‰) but varies substantially between locations

Characterization of a real-time tracer for isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

DOE PAGES

Hu, W. W.; Campuzano-Jost, P.; Palm, B. B.; ...

2015-10-23

Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene oxidation pathways, was quantified by applying positive matrix factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of organic aerosol (OA) in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the Southern Oxidant and Aerosol Study (SOAS), 78 % of PMF-resolved IEPOX-SOA is accountedmore » by the measured IEPOX-SOA molecular tracers (2-methyltetrols, C5-Triols, and IEPOX-derived organosulfate and its dimers), making it the highest level of molecular identification of an ambient SOA component to our knowledge. An enhanced signal at C 5H 6O + ( m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine f C5H6O ( f C5H6O= C 5H 6O +/OA) across multiple field, chamber, and source data sets. A background of ~ 1.7 ± 0.1 ‰ (‰ = parts per thousand) is observed in studies strongly influenced by urban, biomass-burning, and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.6 ‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0 ‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7 ‰), which leaves some room to separate both contributions to OA. Locations strongly influenced by isoprene emissions under low-NO levels had higher f C5H6O (~ 6.5 ± 2.2 ‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. f C5H6O in IEPOX-SOA is always elevated (12–40 ‰) but varies substantially between locations

Steady increase of secondary organic aerosol mass concentration and light extinction during the CARES 2010 Field Campaign

NASA Astrophysics Data System (ADS)

Gyawali, M. S.; Arnott, W. P.; Flowers, B. A.; Dubey, M. K.; Atkinson, D. B.; Song, C.; Zaveri, R. A.; Setyan, A.; Zhang, Q.; Mazzoleni, C.; Gorkowski, K.

2011-12-01

We present multispectral (355, 375, 405, 532, 870, 781, and 1047 nm) aerosol light absorption and scattering measurements for the 2010 Carbonaceous Aerosols and Radiative Effects (CARES) campaign in Sacramento, CA and the Sierra Nevada foothills. The short wavelength scattering at both sites gradually increased during the last 10 days of the campaign as diagnosed by a systematic increase in the Ångström exponent of scattering. The UV and near UV enhanced scattering was likely a consequence of the ultra and sub-micron aerosol which began to grow vigorously in the size range where scattering at shorter wavelengths begins to increase. Multispectral aerosol light absorption coefficients suggest the absence of short wavelength light absorption by brown carbon. Aerosol mass spectrometer data also shows the steady increase of secondary organic aerosol during the last 10 days of CARES. The time series of the measurements made between the two sites (T0 and T1) separated by the slope of the foothills are strikingly similar, except for isolated night time episodes of enhanced absorption at T0. This is possibly due to paving events or other nocturnal emissions markers

Spatial and temporal variations of aerosols around Beijing in summer 2006: 2. Local and column aerosol optical properties

NASA Astrophysics Data System (ADS)

Matsui, H.; Koike, M.; Kondo, Y.; Takegawa, N.; Fast, J. D.; PöSchl, U.; Garland, R. M.; Andreae, M. O.; Wiedensohler, A.; Sugimoto, N.; Zhu, T.

2010-11-01

Model calculations were conducted using the Weather Research and Forecasting model coupled with chemistry (WRF-chem) for the region around Beijing, China, in the summer of 2006, when the CAREBeijing-2006 intensive campaign was conducted. In this paper, we interpret aerosol optical properties in terms of aerosol mass concentrations and their chemical compositions by linking model calculations with measurements. The model calculations generally captured the observed variability of various surface and column aerosol optical parameters in and around Beijing. At the surface, the spatial and temporal variations of aerosol absorption and scattering coefficients corresponded well to those of elemental carbon and sulfate mass concentrations, respectively, and were controlled by local-scale (<100 km and <24 hours) and regional-scale (<500 km and <3 days) emissions, respectively. The contribution of secondary aerosols and their water uptake increased with altitude within the planetary boundary layer. This variation led to a considerable increase in column aerosol optical depth and was responsible for the differences in regional and temporal variations between surface and column aerosol optical properties around Beijing. These processes are expected to be common in other megacity regions as well. Model calculations, however, underestimated or overestimated the absolute levels of aerosol optical properties in and around Beijing by up to 60%. Sensitivity studies showed that these discrepancies were mostly due to the uncertainties in aerosol mixing state and aerosol density (affecting mass extinction efficiency) in the model calculations. Good agreement with measurements is achieved when these aerosol properties are accurately predicted or assumed; however, significant bias can result when these properties are inadequately treated, even if total aerosol mass concentrations are reproduced well in the model calculations.

Estimation of atmospheric columnar organic matter (OM) mass concentration from remote sensing measurements of aerosol spectral refractive indices

NASA Astrophysics Data System (ADS)

Zhang, Ying; Li, Zhengqiang; Sun, Yele; Lv, Yang; Xie, Yisong

2018-04-01

Aerosols have adverse effects on human health and air quality, changing Earth's energy balance and lead to climate change. The components of aerosol are important because of the different spectral characteristics. Based on the low hygroscopic and high scattering properties of organic matter (OM) in fine modal atmospheric aerosols, we develop an inversion algorithm using remote sensing to obtain aerosol components including black carbon (BC), organic matter (OM), ammonium nitrate-like (AN), dust-like (DU) components and aerosol water content (AW). In the algorithm, the microphysical characteristics (i.e. volume distribution and complex refractive index) of particulates are preliminarily separated to fine and coarse modes, and then aerosol components are retrieved using bimodal parameters. We execute the algorithm using remote sensing measurements of sun-sky radiometer at AERONET site (Beijing RADI) in a period from October of 2014 to January of 2015. The results show a reasonable distribution of aerosol components and a good fit for spectral feature calculations. The mean OM mass concentration in atmospheric column is account for 14.93% of the total and 56.34% of dry and fine-mode aerosol, being a fairly good correlation (R = 0.56) with the in situ observations near the surface layer.

Characterization of Florida red tide aerosol and the temporal profile of aerosol concentration.

PubMed

Cheng, Yung Sung; Zhou, Yue; Pierce, Richard H; Henry, Mike; Baden, Daniel G

2010-05-01

Red tide aerosols containing aerosolized brevetoxins are produced during the red tide bloom and transported by wind to coastal areas of Florida. This study reports the characterization of Florida red tide aerosols in human volunteer studies, in which an asthma cohort spent 1h on Siesta Beach (Sarasota, Florida) during aerosolized red tide events and non-exposure periods. Aerosol concentrations, brevetoxin levels, and particle size distribution were measured. Hourly filter samples were taken and analyzed for brevetoxin and NaCl concentrations. In addition, the aerosol mass concentration was monitored in real time. The results indicated that during a non-exposure period in October 2004, no brevetoxin was detected in the water, resulting in non-detectable levels of brevetoxin in the aerosol. In March 2005, the time-averaged concentrations of brevetoxins in water samples were moderate, in the range of 5-10 microg/L, and the corresponding brevetoxin level of Florida red tide aerosol ranged between 21 and 39 ng/m(3). The temporal profiles of red tide aerosol concentration in terms of mass, NaCl, and brevetoxin were in good agreement, indicating that NaCl and brevetoxins are components of the red tide aerosol. By continuously monitoring the marine aerosol and wind direction at Siesta Beach, we observed that the marine aerosol concentration varied as the wind direction changed. The temporal profile of the Florida red tide aerosol during a sampling period could be explained generally with the variation of wind direction. Copyright 2009 Elsevier Ltd. All rights reserved.

50Gb/s PAM-4 oxide VCSEL development progress at Broadcom

NASA Astrophysics Data System (ADS)

Wang, Jingyi; Murty, M. V. Ramana; Wang, Charlie; Hui, David; Lehman Harren, Ann; Chang, Hsu-Hao; Feng, Zheng-Wen; Fanning, Thomas R.; Sridhara, Aaditya; Taslim, Sumitro-Joyo; Cai, Xinle; Chu, Jason; Giovane, Laura M.

2017-02-01

This paper will review the device design and performance of Broadcom's 50Gb/s PAM-4 VCSEL to enable the next generation of transceivers using a PAM-4 advanced modulation scheme at 25-28 GBd. The VCSEL has been optimized to minimize noise and improve dynamic performance for cleaner eyes. Preliminary wear out lifetime studies indicate that the time to 1% failure exceeds 10 years, making the VCSELs suitable for data communication applications.

Chemical characterization of long-range transport biomass burning emissions to the Himalayas: insights from high-resolution aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Zhang, Xinghua; Xu, Jianzhong; Kang, Shichang; Liu, Yanmei; Zhang, Qi

2018-04-01

An intensive field measurement was conducted at a remote, background, high-altitude site (Qomolangma Station, QOMS, 4276 m a.s.l.) in the northern Himalayas, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) along with other collocated instruments. The field measurement was performed from 12 April to 12 May 2016 to chemically characterize the high time-resolved submicron particulate matter (PM1) and obtain the dynamic processes (emissions, transport, and chemical evolution) of biomass burning (BB), frequently transported from South Asia to the Himalayas during pre-monsoon season. Overall, the average (±1σ) PM1 mass concentration was 4.44 (±4.54) µg m-3 for the entire study, which is comparable with those observed at other remote sites worldwide. Organic aerosol (OA) was the dominant PM1 species (accounting for 54.3 % of total PM1 on average) followed by black carbon (BC) (25.0 %), sulfate (9.3 %), ammonium (5.8 %), nitrate (5.1 %), and chloride (0.4 %). The average size distributions of PM1 species all peaked at an overlapping accumulation mode (˜ 500 nm), suggesting that aerosol particles were internally well-mixed and aged during long-range transport. Positive matrix factorization (PMF) analysis on the high-resolution organic mass spectra identified three distinct OA factors, including a BB-related OA (BBOA, 43.7 %), a nitrogen-containing OA (NOA, 13.9 %) and a more-oxidized oxygenated OA (MO-OOA, 42.4 %). Two polluted episodes with enhanced PM1 mass loadings and elevated BBOA contributions from the west and southwest of QOMS during the study were observed. A typical BB plume was investigated in detail to illustrate the chemical evolution of aerosol characteristics under distinct air mass origins, meteorological conditions, and atmospheric oxidation processes.

Informing Aerosol Transport Models With Satellite Multi-Angle Aerosol Measurements

NASA Technical Reports Server (NTRS)

Limbacher, J.; Patadia, F.; Petrenko, M.; Martin, M. Val; Chin, M.; Gaitley, B.; Garay, M.; Kalashnikova, O.; Nelson, D.; Scollo, S.

2011-01-01

As the aerosol products from the NASA Earth Observing System's Multi-angle Imaging SpectroRadiometer (MISR) mature, we are placing greater focus on ways of using the aerosol amount and type data products, and aerosol plume heights, to constrain aerosol transport models. We have demonstrated the ability to map aerosol air-mass-types regionally, and have identified product upgrades required to apply them globally, including the need for a quality flag indicating the aerosol type information content, that varies depending upon retrieval conditions. We have shown that MISR aerosol type can distinguish smoke from dust, volcanic ash from sulfate and water particles, and can identify qualitative differences in mixtures of smoke, dust, and pollution aerosol components in urban settings. We demonstrated the use of stereo imaging to map smoke, dust, and volcanic effluent plume injection height, and the combination of MISR and MODIS aerosol optical depth maps to constrain wildfire smoke source strength. This talk will briefly highlight where we stand on these application, with emphasis on the steps we are taking toward applying the capabilities toward constraining aerosol transport models, planet-wide.

Quantification of marine aerosol subgrid variability and its correlation with clouds based on high-resolution regional modeling: Quantifying Aerosol Subgrid Variability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Guangxing; Qian, Yun; Yan, Huiping

One limitation of most global climate models (GCMs) is that with the horizontal resolutions they typically employ, they cannot resolve the subgrid variability (SGV) of clouds and aerosols, adding extra uncertainties to the aerosol radiative forcing estimation. To inform the development of an aerosol subgrid variability parameterization, here we analyze the aerosol SGV over the southern Pacific Ocean simulated by the high-resolution Weather Research and Forecasting model coupled to Chemistry. We find that within a typical GCM grid, the aerosol mass subgrid standard deviation is 15% of the grid-box mean mass near the surface on a 1 month mean basis.more » The fraction can increase to 50% in the free troposphere. The relationships between the sea-salt mass concentration, meteorological variables, and sea-salt emission rate are investigated in both the clear and cloudy portion. Under clear-sky conditions, marine aerosol subgrid standard deviation is highly correlated with the standard deviations of vertical velocity, cloud water mixing ratio, and sea-salt emission rates near the surface. It is also strongly connected to the grid box mean aerosol in the free troposphere (between 2 km and 4 km). In the cloudy area, interstitial sea-salt aerosol mass concentrations are smaller, but higher correlation is found between the subgrid standard deviations of aerosol mass and vertical velocity. Additionally, we find that decreasing the model grid resolution can reduce the marine aerosol SGV but strengthen the correlations between the aerosol SGV and the total water mixing ratio (sum of water vapor, cloud liquid, and cloud ice mixing ratios).« less

Aqueous aerosol SOA formation: impact on aerosol physical properties.

PubMed

Woo, Joseph L; Kim, Derek D; Schwier, Allison N; Li, Ruizhi; McNeill, V Faye

2013-01-01

Organic chemistry in aerosol water has recently been recognized as a potentially important source of secondary organic aerosol (SOA) material. This SOA material may be surface-active, therefore potentially affecting aerosol heterogeneous activity, ice nucleation, and CCN activity. Aqueous aerosol chemistry has also been shown to be a potential source of light-absorbing products ("brown carbon"). We present results on the formation of secondary organic aerosol material in aerosol water and the associated changes in aerosol physical properties from GAMMA (Gas-Aerosol Model for Mechanism Analysis), a photochemical box model with coupled gas and detailed aqueous aerosol chemistry. The detailed aerosol composition output from GAMMA was coupled with two recently developed modules for predicting a) aerosol surface tension and b) the UV-Vis absorption spectrum of the aerosol, based on our previous laboratory observations. The simulation results suggest that the formation of oligomers and organic acids in bulk aerosol water is unlikely to perturb aerosol surface tension significantly. Isoprene-derived organosulfates are formed in high concentrations in acidic aerosols under low-NO(x) conditions, but more experimental data are needed before the potential impact of these species on aerosol surface tension may be evaluated. Adsorption of surfactants from the gas phase may further suppress aerosol surface tension. Light absorption by aqueous aerosol SOA material is driven by dark glyoxal chemistry and is highest under high-NO(x) conditions, at high relative humidity, in the early morning hours. The wavelength dependence of the predicted absorption spectra is comparable to field observations and the predicted mass absorption efficiencies suggest that aqueous aerosol chemistry can be a significant source of aerosol brown carbon under urban conditions.

BicPAMS: software for biological data analysis with pattern-based biclustering.

PubMed

Henriques, Rui; Ferreira, Francisco L; Madeira, Sara C

2017-02-02

Biclustering has been largely applied for the unsupervised analysis of biological data, being recognised today as a key technique to discover putative modules in both expression data (subsets of genes correlated in subsets of conditions) and network data (groups of coherently interconnected biological entities). However, given its computational complexity, only recent breakthroughs on pattern-based biclustering enabled efficient searches without the restrictions that state-of-the-art biclustering algorithms place on the structure and homogeneity of biclusters. As a result, pattern-based biclustering provides the unprecedented opportunity to discover non-trivial yet meaningful biological modules with putative functions, whose coherency and tolerance to noise can be tuned and made problem-specific. To enable the effective use of pattern-based biclustering by the scientific community, we developed BicPAMS (Biclustering based on PAttern Mining Software), a software that: 1) makes available state-of-the-art pattern-based biclustering algorithms (BicPAM (Henriques and Madeira, Alg Mol Biol 9:27, 2014), BicNET (Henriques and Madeira, Alg Mol Biol 11:23, 2016), BicSPAM (Henriques and Madeira, BMC Bioinforma 15:130, 2014), BiC2PAM (Henriques and Madeira, Alg Mol Biol 11:1-30, 2016), BiP (Henriques and Madeira, IEEE/ACM Trans Comput Biol Bioinforma, 2015), DeBi (Serin and Vingron, AMB 6:1-12, 2011) and BiModule (Okada et al., IPSJ Trans Bioinf 48(SIG5):39-48, 2007)); 2) consistently integrates their dispersed contributions; 3) further explores additional accuracy and efficiency gains; and 4) makes available graphical and application programming interfaces. Results on both synthetic and real data confirm the relevance of BicPAMS for biological data analysis, highlighting its essential role for the discovery of putative modules with non-trivial yet biologically significant functions from expression and network data. BicPAMS is the first biclustering tool offering the

Source apportionment of lead-containing aerosol particles in Shanghai using single particle mass spectrometry.

PubMed

Zhang, Yaping; Wang, Xiaofei; Chen, Hong; Yang, Xin; Chen, Jianmin; Allen, Jonathan O

2009-01-01

Lead (Pb) in individual aerosol particles was measured using single particle aerosol mass spectrometer (ATOFMS) in the summer of 2007 in Shanghai, China. Pb was found in 3% of particles with diameters in the range 0.1-2.0 microm. Single particle data were analyzed focusing on the particles with high Pb content which were mostly submicron. Using the ART-2a neural network algorithm, these fine Pb-rich particles were classified into eight main classes by their mass spectral patterns. Based on the size distribution, temporal variation of number density, chemical composition and the correlation between different chemical species for each class, three major emission sources were identified. About 45% of the Pb-rich particles contained organic or elemental carbon and were attributed to the emission from coal combustion; particles with good correlation between Cl and Pb content were mostly attributed to waste incineration. One unique class of particles was identified by strong phosphate and Pb signals, which were assigned to emissions from phosphate industry. Other Pb-rich particles included aged sea salt and particles from metallurgical processes.

On the implications of aerosol liquid water and phase separation for organic aerosol mass

EPA Science Inventory

Organic compounds and liquid water are major aerosol constituents in the southeast United States (SE US). Water associated with inorganic constituents (inorganic water) can contribute to the partitioning medium for organic aerosol when relative humidities or organic matter to org...

ACTRIS ACSM intercomparison - Part 2: Intercomparison of ME-2 organic source apportionment results from 15 individual, co-located aerosol mass spectrometers

NASA Astrophysics Data System (ADS)

Fröhlich, R.; Crenn, V.; Setyan, A.; Belis, C. A.; Canonaco, F.; Favez, O.; Riffault, V.; Slowik, J. G.; Aas, W.; Aijälä, M.; Alastuey, A.; Artiñano, B.; Bonnaire, N.; Bozzetti, C.; Bressi, M.; Carbone, C.; Coz, E.; Croteau, P. L.; Cubison, M. J.; Esser-Gietl, J. K.; Green, D. C.; Gros, V.; Heikkinen, L.; Herrmann, H.; Jayne, J. T.; Lunder, C. R.; Minguillón, M. C.; Močnik, G.; O'Dowd, C. D.; Ovadnevaite, J.; Petralia, E.; Poulain, L.; Priestman, M.; Ripoll, A.; Sarda-Estève, R.; Wiedensohler, A.; Baltensperger, U.; Sciare, J.; Prévôt, A. S. H.

2015-06-01

Chemically resolved atmospheric aerosol data sets from the largest intercomparison of the Aerodyne aerosol chemical speciation monitors (ACSMs) performed to date were collected at the French atmospheric supersite SIRTA. In total 13 quadrupole ACSMs (Q-ACSM) from the European ACTRIS ACSM network, one time-of-flight ACSM (ToF-ACSM), and one high-resolution ToF aerosol mass spectrometer (AMS) were operated in parallel for about 3 weeks in November and December~2013. Part 1 of this study reports on the accuracy and precision of the instruments for all the measured species. In this work we report on the intercomparison of organic components and the results from factor analysis source apportionment by positive matrix factorisation (PMF) utilising the multilinear engine 2 (ME-2). Except for the organic contribution of mass-to-charge ratio m/z 44 to the total organics (f44), which varied by factors between 0.6 and 1.3 compared to the mean, the peaks in the organic mass spectra were similar among instruments. The m/z 44 differences in the spectra resulted in a variable f44 in the source profiles extracted by ME-2, but had only a minor influence on the extracted mass contributions of the sources. The presented source apportionment yielded four factors for all 15 instruments: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA), biomass burning-related organic aerosol (BBOA) and secondary oxygenated organic aerosol (OOA). ME-2 boundary conditions (profile constraints) were optimised individually by means of correlation to external data in order to achieve equivalent / comparable solutions for all ACSM instruments and the results are discussed together with the investigation of the influence of alternative anchors (reference profiles). A comparison of the ME-2 source apportionment output of all 15 instruments resulted in relative standard deviations (SD) from the mean between 13.7 and 22.7 % of the source's average mass contribution depending on the

Applications of High-Resolution Electrospray Ionization Mass Spectrometry to Measurements of Average Oxygen to Carbon Ratios in Secondary Organic Aerosols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bateman, Adam P.; Laskin, Julia; Laskin, Alexander

2012-07-02

The applicability of high resolution electrospray ionization mass spectrometry (HR ESI-MS) to measurements of the average oxygen to carbon ratio (O/C) in organic aerosols was investigated. Solutions with known average O/C containing up to 10 standard compounds representative of secondary organic aerosol (SOA) were analyzed and corresponding electrospray ionization efficiencies were quantified. The assumption of equal ionization efficiency commonly used in estimating O/C ratios of organic aerosols was found to be reasonably accurate. We found that the accuracy of the measured O/C ratios increases by averaging the values obtained from both (+) and (-) modes. A correlation was found betweenmore » the ratio of the ionization efficiencies in the positive and negative ESI modes with the octanol-water partition constant, and more importantly, with the compound's O/C. To demonstrate the utility of this correlation for estimating average O/C values of unknown mixtures, we analyzed the ESI (+) and ESI (-) data for SOA produced by oxidation of limonene and isoprene and compared to online O/C measurements using an aerosol mass spectrometer (AMS). This work demonstrates that the accuracy of the HR ESI-MS methods is comparable to that of the AMS, with the added benefit of molecular identification of the aerosol constituents.« less

[Effects of biochar and PAM application on saline soil hydraulic properties of coastal reclamation region].

PubMed

Cao, Yu Tong; She, Dong Li

2017-11-01

Disc infiltration tests were carried out to study the soil infiltration characteristics under different rates of soil amendments application, and to investigate the effects of biochar and polyacrylamide (PAM) application on saline soil hydraulic properties, pore characteristics and contribution of each pore to soil water flow in coastal reclamation region. The results showed that soil satura-ted hydraulic conductivity increased by 46.4% when biochar was applied at 2% compared with the control, and decreased with increasing PAM application. The total effective soil porosity and r>100 μm pores were increased by 8.3% and 10.2% (P<0.05) with the application of 2% biochar alone. The total effective soil porosity and different radius pores decreased with the PAM application. Particularly, the total effective soil porosity decreased markedly when PAM was applied at 1‰ and the reduction was up to 88%. With the application of biochar and PAM, the contribution of r<100 μm pores to water flow decreased and the pores with r>500 μm played a major role in determining water flows.

Feasibility investigation of oily wastewater treatment by combination of zinc and PAM in coagulation/flocculation.

PubMed

Zeng, Yubin; Yang, Changzhu; Zhang, Jingdong; Pu, Wenhong

2007-08-25

Poly-zinc silicate (PZSS) is a new type of coagulant with cationic polymer synthesized by polysilicic acid and zinc sulfate. It has been used in several sorts of wastewaters treatment, but not used in oily wastewater treatment. In this study, we investigated the coagulation/flocculation of oil and suspended solids in heavy oil wastewater (HOW) by PZSS and anion polyacrylamide (A-PAM). The properties of PZSS cooperated with A-PAM were compared with PAC and PFS in dosages, PAMs amount, settling time, pH value and flocs morphology. The results showed that PZSS was more efficient than PAC and PFS. Under the optimum experimental conditions of coagulation/flocculation (dosage: 100mg/L, A-PAM dosage: 1.0mg/L, settling time time: 40min and pH 6.5-9.5), more than 99% of oil was removed and suspended solid value less than 5mg/L by using PZSS cooperated with A-PAM, which could satisfy the demands of the pre-treatment process for HOW to be reused in the steam boiler or recycled into the injecting well.

Reduction in biomass burning aerosol light absorption upon humidification: roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

NASA Astrophysics Data System (ADS)

Lewis, K. A.; Arnott, W. P.; Moosmüller, H.; Chakrabarty, R. K.; Carrico, C. M.; Kreidenweis, S. M.; Day, D. E.; Malm, W. C.; Laskin, A.; Jimenez, J. L.; Ulbrich, I. M.; Huffman, J. A.; Onasch, T. B.; Trimborn, A.; Liu, L.; Mishchenko, M. I.

2009-11-01

Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used were Montana ponderosa pine (Pinus ponderosa), southern California chamise (Adenostoma fasciculatum), and Florida saw palmetto (Serenoa repens). Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients revealed a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: (1) shielding of inner monomers after particle consolidation or collapse with water uptake; (2) the lower case contribution of mass transfer through evaporation and condensation at high relative humidity (RH) to the usual heat transfer pathway for energy release by laser-heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

Reduction in biomass burning aerosol light absorption upon humidification: roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

NASA Astrophysics Data System (ADS)

Lewis, K. A.; Arnott, W. P.; Moosmüller, H.; Chakrabarty, R. K.; Carrico, C. M.; Kreidenweis, S. M.; Day, D. E.; Malm, W. C.; Laskin, A.; Jimenez, J. L.; Ulbrich, I. M.; Huffman, J. A.; Onasch, T. B.; Trimborn, A.; Liu, L.; Mishchenko, M. I.

2009-07-01

Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used are Montana ponderosa pine (Pinus ponderosa), southern California chamise (Adenostoma fasciculatum), and Florida saw palmetto (Serenoa repens). Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients reveal a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: 1. Shielding of inner monomers after particle consolidation or collapse with water uptake; 2. The contribution of mass transfer through evaporation and condensation at high relative humidity to the usual heat transfer pathway for energy release by laser-heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

Cas4 Facilitates PAM-Compatible Spacer Selection during CRISPR Adaptation.

PubMed

Kieper, Sebastian N; Almendros, Cristóbal; Behler, Juliane; McKenzie, Rebecca E; Nobrega, Franklin L; Haagsma, Anna C; Vink, Jochem N A; Hess, Wolfgang R; Brouns, Stan J J

2018-03-27

CRISPR-Cas systems adapt their immunological memory against their invaders by integrating short DNA fragments into clustered regularly interspaced short palindromic repeat (CRISPR) loci. While Cas1 and Cas2 make up the core machinery of the CRISPR integration process, various class I and II CRISPR-Cas systems encode Cas4 proteins for which the role is unknown. Here, we introduced the CRISPR adaptation genes cas1, cas2, and cas4 from the type I-D CRISPR-Cas system of Synechocystis sp. 6803 into Escherichia coli and observed that cas4 is strictly required for the selection of targets with protospacer adjacent motifs (PAMs) conferring I-D CRISPR interference in the native host Synechocystis. We propose a model in which Cas4 assists the CRISPR adaptation complex Cas1-2 by providing DNA substrates tailored for the correct PAM. Introducing functional spacers that target DNA sequences with the correct PAM is key to successful CRISPR interference, providing a better chance of surviving infection by mobile genetic elements. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Autonomous NanoTechnology Swarm (ANTS) Prospecting Asteroid Mission (PAM), Asteroid Proximity Operations

NASA Technical Reports Server (NTRS)

Marr, Greg; Cooley, Steve; Roithmayr, Carlos; Kay-Bunnell, Linda; Williams, Trevor

2004-01-01

The Autonomous NanoTechnology Swarm (ANTS) is a generic mission architecture based on spatially distributed spacecraft, autonomous and redundant components, and hierarchical organization. The ANTS Prospecting Asteroid Mission (PAM) is an ANTS application which will nominally use a swarm of 1000 spacecraft. There would be 10 types of "specialists" with common spacecraft buses. There would be 10 subswarms of approximately 100 spacecraft each or approximately 10 of each specialist in each swarm. The ANTS PAM primary objective is the exploration of the asteroid belt in search of resources and material with astrobiologically relevant origins and signatures. The ANTS PAM spacecraft will nominally be released from a station in an Earth-Moon L1 libration point orbit, and they will use Solar sails for propulsion. The sail structure would be highly flexible, capable of changing morphology to change cross-section for capture of sunlight or to form effective "tip vanes" for attitude control. ANTS PAM sails would be capable of full to partial deployment, to change effective sail area and center of pressure, and thus allow attitude control. Results of analysis of a transfer trajectory from Earth to a sample target asteroid will be presented. ANTS PAM will require continuous coverage of different asteroid locations as close as one to two asteroid "diameters" from the surface of the asteroid for periods of science data collection during asteroid proximity operations. Hovering spacecraft could meet the science data collection objectives. The results of hovering analysis will be presented. There are locations for which hovering is not possible, for example on the illuminated side of the asteroid. For cases where hovering is not possible, the results of utilizing asteroid formations to orbit the asteroid and achieve the desired asteroid viewing will be presented for sample asteroids. The ability of ANTS PAM to reduce the area of the solar sail during asteroid proximity operations is

A Miniature System for Separating Aerosol Particles and Measuring Mass Concentrations

PubMed Central

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

2010-01-01

We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM) sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d < 2.28 μm, 2.28 μm ≤ d ≤ 3.20 μm, d > 3.20 μm. The QCM sensors were coated with a hydrogel, which was found to be a reliable adhesive for capturing aerosol particles. The QCM sensor coated with hydrogel was used to measure the mass loading of particles by utilizing its characteristic of resonant frequency shift. An integrated system has been demonstrated. PMID:22319317

Scaling single-wavelength optical interconnects to 180 Gb/s with PAM-M and pulse shaping

NASA Astrophysics Data System (ADS)

Dris, Stefanos; Bakopoulos, Paraskevas; Argyris, Nikolaos; Spatharakis, Christos; Avramopoulos, Hercules

2016-03-01

Faced with surging datacenter traffic demand, system designers are turning to multi-level optical modulation with direct detection as the means of reaching 100 Gb/s in a single optical lane; a further upgrade to 400 Gb/s is envisaged through wavelength-multiplexing of multiple 100 Gb/s strands. In terms of modulation formats, PAM-4 and PAM-8 are considered the front-runners, striking a good balance between bandwidth-efficiency and implementation complexity. In addition, the emergence of energy-efficient, high-speed CMOS digital-to-analog converters (DACs) opens up new possibilities: Spectral shaping through digital filtering will allow squeezing even more data through low-cost, low-bandwidth electro-optic components. In this work we demonstrate an optical interconnect based on an EAM that is driven directly with sub-volt electrical swing by a 65 GSa/s arbitrary waveform generator (AWG). Low-voltage drive is particularly attractive since it allows direct interfacing with the switch/server ASIC, eliminating the need for dedicated, power-hungry and expensive electrical drivers. Single-wavelength throughputs of 180 and 120 Gb/s are experimentally demonstrated with 60 Gbaud optical PAM-8 and PAM-4 respectively. Successful transmission over 1250 m SMF is achieved with direct-detection, using linear equalization via offline digital signal processing in order to overcome the strong bandwidth limitation of the overall link (~20 GHz). The suitability of Nyquist pulse shaping for optical interconnects is also investigated experimentally with PAM-4 and PAM-8, at a lower symbol rate of 40 Gbaud (limited by the sampling rate of the AWG). To the best of our knowledge, the rates achieved are the highest ever using optical PAM-M formats.

GPR40 partial agonists and AgoPAMs: Differentiating effects on glucose and hormonal secretions in the rodent

PubMed Central

Pachanski, Michele J.; Kirkland, Melissa E.; Kosinski, Daniel T.; Mane, Joel; Cheewatrakoolpong, Boonlert; Xue, Jiyan; Szeto, Daphne; Forrest, Gail; Miller, Corin; Bunzel, Michelle; Plummer, Christopher W.; Chobanian, Harry R.; Miller, Michael W.; Souza, Sarah; Thomas-Fowlkes, Brande S.; Ogawa, Aimie M.; Weinglass, Adam B.; Di Salvo, Jerry; Li, Xiaoyan; Feng, Yue; Tatosian, Daniel A.; Howard, Andrew D.; Colletti, Steven L.

2017-01-01

GPR40 agonists are effective antidiabetic agents believed to lower glucose through direct effects on the beta cell to increase glucose stimulated insulin secretion. However, not all GPR40 agonists are the same. Partial agonists lower glucose through direct effects on the pancreas, whereas GPR40 AgoPAMs may incorporate additional therapeutic effects through increases in insulinotrophic incretins secreted by the gut. Here we describe how GPR40 AgoPAMs stimulate both insulin and incretin secretion in vivo over time in diabetic GK rats. We also describe effects of AgoPAMs in vivo to lower glucose and body weight beyond what is seen with partial GPR40 agonists in both the acute and chronic setting. Further comparisons of the glucose lowering profile of AgoPAMs suggest these compounds may possess greater glucose control even in the presence of elevated glucagon secretion, an unexpected feature observed with both acute and chronic treatment with AgoPAMs. Together these studies highlight the complexity of GPR40 pharmacology and the potential additional benefits AgoPAMs may possess above partial agonists for the diabetic patient. PMID:29053717

ACTRIS ACSM intercomparison - Part 2: Intercomparison of ME-2 organic source apportionment results from 15 individual, co-located aerosol mass spectrometers

NASA Astrophysics Data System (ADS)

Fröhlich, R.; Crenn, V.; Setyan, A.; Belis, C. A.; Canonaco, F.; Favez, O.; Riffault, V.; Slowik, J. G.; Aas, W.; Aijälä, M.; Alastuey, A.; Artiñano, B.; Bonnaire, N.; Bozzetti, C.; Bressi, M.; Carbone, C.; Coz, E.; Croteau, P. L.; Cubison, M. J.; Esser-Gietl, J. K.; Green, D. C.; Gros, V.; Heikkinen, L.; Herrmann, H.; Jayne, J. T.; Lunder, C. R.; Minguillón, M. C.; Močnik, G.; O'Dowd, C. D.; Ovadnevaite, J.; Petralia, E.; Poulain, L.; Priestman, M.; Ripoll, A.; Sarda-Estève, R.; Wiedensohler, A.; Baltensperger, U.; Sciare, J.; Prévôt, A. S. H.

2015-02-01

Chemically resolved atmospheric aerosol data sets from the largest intercomparison of the Aerodyne aerosol chemical speciation monitors (ACSM) performed to date were collected at the French atmospheric supersite SIRTA. In total 13 quadrupole ACSMs (Q-ACSM) from the European ACTRIS ACSM network, one time-of-flight ACSM (ToF-ACSM), and one high-resolution ToF aerosol mass spectrometer (AMS) were operated in parallel for about three weeks in November and December 2013. Part 1 of this study reports on the accuracy and precision of the instruments for all the measured species. In this work we report on the intercomparison of organic components and the results from factor analysis source apportionment by positive matrix factorisation (PMF) utilising the multilinear engine 2 (ME-2). Except for the organic contribution of m/z 44 to the total organics (f44), which varied by factors between 0.6 and 1.3 compared to the mean, the peaks in the organic mass spectra were similar among instruments. The m/z 44 differences in the spectra resulted in a variable f44 in the source profiles extracted by ME-2, but had only a minor influence on the extracted mass contributions of the sources. The presented source apportionment yielded four factors for all 15 instruments: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA), biomass burning-related organic aerosol (BBOA) and secondary oxygenated organic aerosol (OOA). Individual application and optimisation of the ME-2 boundary conditions (profile constraints) are discussed together with the investigation of the influence of alternative anchors (reference profiles). A comparison of the ME-2 source apportionment output of all 15 instruments resulted in relative SD from the mean between 13.7 and 22.7% of the source's average mass contribution depending on the factors (HOA: 14.3 ± 2.2%, COA: 15.0 ± 3.4%, OOA: 41.5 ± 5.7%, BBOA: 29.3 ± 5.0%). Factors which tend to be subject to minor factor mixing (in this case COA

A new application of hierarchical cluster analysis to investigate organic peaks in bulk mass spectra obtained with an Aerodyne Aerosol Mass Spectrometer

NASA Astrophysics Data System (ADS)

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

2006-12-01

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

Series Pneumatic Artificial Muscles (sPAMs) and Application to a Soft Continuum Robot.

PubMed

Greer, Joseph D; Morimoto, Tania K; Okamura, Allison M; Hawkes, Elliot W

2017-01-01

We describe a new series pneumatic artificial muscle (sPAM) and its application as an actuator for a soft continuum robot. The robot consists of three sPAMs arranged radially round a tubular pneumatic backbone. Analogous to tendons, the sPAMs exert a tension force on the robot's pneumatic backbone, causing bending that is approximately constant curvature. Unlike a traditional tendon driven continuum robot, the robot is entirely soft and contains no hard components, making it safer for human interaction. Models of both the sPAM and soft continuum robot kinematics are presented and experimentally verified. We found a mean position accuracy of 5.5 cm for predicting the end-effector position of a 42 cm long robot with the kinematic model. Finally, closed-loop control is demonstrated using an eye-in-hand visual servo control law which provides a simple interface for operation by a human. The soft continuum robot with closed-loop control was found to have a step-response rise time and settling time of less than two seconds.

Series Pneumatic Artificial Muscles (sPAMs) and Application to a Soft Continuum Robot

PubMed Central

Greer, Joseph D.; Morimoto, Tania K.; Okamura, Allison M.; Hawkes, Elliot W.

2017-01-01

We describe a new series pneumatic artificial muscle (sPAM) and its application as an actuator for a soft continuum robot. The robot consists of three sPAMs arranged radially round a tubular pneumatic backbone. Analogous to tendons, the sPAMs exert a tension force on the robot’s pneumatic backbone, causing bending that is approximately constant curvature. Unlike a traditional tendon driven continuum robot, the robot is entirely soft and contains no hard components, making it safer for human interaction. Models of both the sPAM and soft continuum robot kinematics are presented and experimentally verified. We found a mean position accuracy of 5.5 cm for predicting the end-effector position of a 42 cm long robot with the kinematic model. Finally, closed-loop control is demonstrated using an eye-in-hand visual servo control law which provides a simple interface for operation by a human. The soft continuum robot with closed-loop control was found to have a step-response rise time and settling time of less than two seconds. PMID:29379672

Accelerated Biofluid Filling in Complex Microfluidic Networks by Vacuum-Pressure Accelerated Movement (V-PAM).

PubMed

Yu, Zeta Tak For; Cheung, Mei Ki; Liu, Shirley Xiaosu; Fu, Jianping

2016-09-01

Rapid fluid transport and exchange are critical operations involved in many microfluidic applications. However, conventional mechanisms used for driving fluid transport in microfluidics, such as micropumping and high pressure, can be inaccurate and difficult for implementation for integrated microfluidics containing control components and closed compartments. Here, a technology has been developed termed Vacuum-Pressure Accelerated Movement (V-PAM) capable of significantly enhancing biofluid transport in complex microfluidic environments containing dead-end channels and closed chambers. Operation of the V-PAM entails a pressurized fluid loading into microfluidic channels where gas confined inside can rapidly be dissipated through permeation through a thin, gas-permeable membrane sandwiched between microfluidic channels and a network of vacuum channels. Effects of different structural and operational parameters of the V-PAM for promoting fluid filling in microfluidic environments have been studied systematically. This work further demonstrates the applicability of V-PAM for rapid filling of temperature-sensitive hydrogels and unprocessed whole blood into complex irregular microfluidic networks such as microfluidic leaf venation patterns and blood circulatory systems. Together, the V-PAM technology provides a promising generic microfluidic tool for advanced fluid control and transport in integrated microfluidics for different microfluidic diagnosis, organs-on-chips, and biomimetic studies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Criteria for significance of simultaneous presence of both condensible vapors and aerosol particles on mass transfer (deposition) rates

NASA Technical Reports Server (NTRS)

Gokoglu, S. A.

1987-01-01

The simultaneous presence of aerosol particles and condensible vapors in a saturated boundary layer which may affect deposition rates to subcooled surfaces because of vapor-particle interactions is discussed. Scavenging of condensible vapors by aerosol particles may lead to increased particle size and decreased vapor mass fraction, which alters both vapor and particle deposition rates. Particles, if sufficiently concentrated, may also coagulate. Criteria are provided to assess the significance of such phenomena when particles are already present in the mainstream and are not created inside the boundary layer via homogeneous nucleation. It is determined that there is direct proportionality with: (1) the mass concentration of both condensible vapors and aerosol particles; and (2) the square of the boundary layer thickness to particle diameter ratio (delta d sub p) square. Inverse proportionality was found for mainstream to surface temperature difference if thermophoresis dominates particle transport. It is concluded that the square of the boundary layer thickness to particle diameter ratio is the most critical factor to consider in deciding when to neglect vapor-particle interactions.

Criteria for significance of simultaneous presence of both condensible vapors and aerosol particles on mass transfer (deposition) rates

NASA Technical Reports Server (NTRS)

Gokoglu, S. A.

1986-01-01

The simultaneous presence of aerosol particles and condensible vapors in a saturated boundary layer which may affect deposition rates to subcooled surfaces because of vapor-particle interactions is discussed. Scavenging of condensible vapors by aerosol particles may lead to increased particle size and decreased vapor mass fraction, which alters both vapor and particle deposition rates. Particles, if sufficiently concentrated, may also coagulate. Criteria are provided to assess the significance of such phenomena when particles are already present in the mainstream and are not created inside the boundary layer via homogeneous nucleation. It is determined that there is direct proportionality with: (1) the mass concentration of both condensible vapors and aerosol particles; and (2) the square of the boundary layer thickness to particle diameter ratio (delta d sub p) square. Inverse proportionality was found for mainstream to surface temperature difference if thermophoresis dominates particle transport. It is concluded that the square of the boundary layer thickness to particle diameter ratio is the most critical factor to consider in deciding when to neglect vapor-particle interactions.

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

2013-05-07

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

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

The MAC aerosol climatology

NASA Astrophysics Data System (ADS)

Kinne, S.

2015-12-01

Aerosol is highly diverse in space and time. And many different aerosol optical properties are needed (consistent to each other) for the determination of radiative effects. To sidestep a complex (and uncertain) aerosol treatment (emission to mass to optics) a monthly gridded climatology for aerosol properties has been developed. This MPI Aerosol Climatology (MAC) is strongly tied to observational statistics for aerosol column optical properties by AERONET (over land) and by MAN (over oceans). To fill spatial gaps, to address decadal change and to address vertical variability, these sparsely distributed local data are extended with central data of an ensemble of output from global models with complex aerosol modules. This data merging in performed for aerosol column amount (AOD), for aerosol size (AOD,fine) and for aerosol absorption (AAOD). The resulting MAC aerosol climatology is an example for the combination of high quality local observations with spatial, temporal and vertical context from model simulations.

The potential of LIRIC to validate the vertical profiles of the aerosol mass concentration estimated by an air quality model

NASA Astrophysics Data System (ADS)

Siomos, Nikolaos; Filoglou, Maria; Poupkou, Anastasia; Liora, Natalia; Dimopoulos, Spyros; Melas, Dimitris; Chaikovsky, Anatoli; Balis, Dimitris

2015-04-01

Vertical profiles of the aerosol mass concentration derived by a retrieval algorithm that uses combined sunphotometer and LIDAR data (LIRIC) were used in order to validate the mass concentration profiles estimated by the air quality model CAMx. LIDAR and CIMEL measurements of the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki were used for this validation.The aerosol mass concentration profiles of the fine and coarse mode derived by CAMx were compared with the respective profiles derived by the retrieval algorithm. For the coarse mode particles, forecasts of the Saharan dust transportation model BSC-DREAM8bV2 were also taken into account. Each of the retrieval algorithm's profiles were matched to the models' profile with the best agreement within a time window of four hours before and after the central measurement. OPAC, a software than can provide optical properties of aerosol mixtures, was also employed in order to calculate the angstrom exponent and the lidar ratio values for 355nm and 532nm for each of the model's profiles aiming in a comparison with the angstrom exponent and the lidar ratio values derived by the retrieval algorithm for each measurement. The comparisons between the fine mode aerosol concentration profiles resulted in a good agreement between CAMx and the retrieval algorithm, with the vertical mean bias error never exceeding 7 μgr/m3. Concerning the aerosol coarse mode concentration profiles both CAMx and BSC-DREAM8bV2 values are severely underestimated, although, in cases of Saharan dust transportation events there is an agreement between the profiles of BSC-DREAM8bV2 model and the retrieval algorithm.

Determination of particulate lead during MILAGRO/MCMA-2006 using Aerosol Mass Spectrometry

NASA Astrophysics Data System (ADS)

Salcedo, D.; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; de Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L.

2010-02-01

We report the first measurements of particulate lead (Pb) from Aerodyne Aerosol Mass Spectrometers, which were deployed in and around Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO)/Mexico City Metropolitan Area 2006 (MCMA-2006) field campaigns. The high resolution mass spectrometer of one of the AMS instruments (HR-AMS) and the measured isotopic ratios unequivocally prove the detection of Pb in ambient particles. A substantial fraction of the lead evaporated slowly from the vaporizer of the instruments, which is indicative of species with low volatility at 600 °C. A model was developed in order to estimate the ambient particulate Pb entering the AMS from the signals in the "open" and the "closed" (or "background") mass spectrum modes of the AMS. The model suggests the presence of at least two lead fractions with ~25% of the Pb signal exhibiting rapid evaporation (1/e decay constant, τ<0.1 s) and ~75% exhibiting slow evaporation (τ~2.4 min) at the T0 urban supersite and a different fraction (70% prompt and 30% slow evaporation) at a site northwest from the metropolitan area (PEMEX site). From laboratory experiments with pure Pb(NO3)2 particles, we estimated that the Pb ionization efficiency relative to nitrate (RIEPb) is 0.5. Comparison of time series of AMS Pb with other measurements carried out at T0 (using Proton Induced X-ray Emission (PIXE), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and single-particle counts from an Aerosol Time-of-Fight Mass Spectrometer (ATOFMS)) shows similar levels (for PIXE and ICP-MS) and substantial correlation. During part of the campaign, sampling at T0 was alternated every 10 min with an Aerosol Concentrator, which enabled the detection of signals for PbCl+ and PbS+ ions. PbS+ displays the signature of a slowly evaporating species, while PbCl+ appears to arise only from fast evaporation, which is likely due to the higher vapor pressure of the compounds generating Pb

Determination of particulate lead using aerosol mass spectrometry: MILAGRO/MCMA-2006 observations

NASA Astrophysics Data System (ADS)

Salcedo, D.; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; de Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L.

2010-06-01

We report the first measurements of particulate lead (Pb) from Aerodyne Aerosol Mass Spectrometers, which were deployed in and around Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO)/Mexico City Metropolitan Area 2006 (MCMA-2006) field campaigns. The high resolution mass spectrometer of one of the AMS instruments (HR-AMS) and the measured isotopic ratios unequivocally prove the detection of Pb in ambient particles. A substantial fraction of the lead evaporated slowly from the vaporizer of the instruments, which is indicative of species with low volatility at 600 °C. A model was developed in order to estimate the ambient particulate Pb entering the AMS from the signals in the "open" and the "closed" (or "background") mass spectrum modes of the AMS. The model suggests the presence of at least two lead fractions with ~25% of the Pb signal exhibiting rapid evaporation (1/e decay constant, τ<0.1 s) and ~75% exhibiting slow evaporation (τ~2.4 min) at the T0 urban supersite and a different fraction (70% prompt and 30% slow evaporation) at a site northwest from the metropolitan area (PEMEX site). From laboratory experiments with pure Pb(NO3)2 particles, we estimated that the Pb ionization efficiency relative to nitrate (RIEPb) is 0.5. Comparison of time series of AMS Pb with other measurements carried out at the T0 supersite during MILAGRO (using Proton Induced X-ray Emission (PIXE), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and single-particle counts from an Aerosol Time-of-Fight Mass Spectrometer (ATOFMS)) shows similar levels (for PIXE and ICP-MS) and substantial correlation. During part of the campaign, sampling at T0 was alternated every 10 min with an Aerosol Concentrator, which enabled the detection of signals for PbCl+ and PbS+ ions. PbS+ displays the signature of a slowly evaporating species, while PbCl+ appears to arise only from fast evaporation, which is likely due to the higher vapor pressure of the

Engineered Cpf1 variants with altered PAM specificities increase genome targeting range

PubMed Central

Gao, Linyi; Cox, David B.T.; Yan, Winston X.; Manteiga, John C.; Schneider, Martin W.; Yamano, Takashi; Nishimasu, Hiroshi; Nureki, Osamu; Crosetto, Nicola; Zhang, Feng

2017-01-01

The RNA-guided endonuclease Cpf1 is a promising tool for genome editing in eukaryotic cells1–7. However, the utility of the commonly used Acidaminococcus sp. BV3L6 Cpf1 (AsCpf1) and Lachnospiraceae bacterium ND2006 Cpf1 (LbCpf1) is limited by their requirement of a TTTV protospacer adjacent motif (PAM) in the DNA substrate. To address this limitation, we performed a structure-guided mutagenesis screen to increase the targeting range of Cpf1. We engineered two AsCpf1 variants carrying the mutations S542R/K607R and S542R/K548V/N552R, which recognize TYCV and TATV PAMs, respectively, with enhanced activities in vitro and in human cells. Genome-wide assessment of off-target activity using BLISS7 assay indicated that these variants retain high DNA targeting specificity, which we further improved by introducing an additional non-PAM-interacting mutation. Introducing the identified mutations at their corresponding positions in LbCpf1 similarly altered its PAM specificity. Together, these variants increase the targeting range of Cpf1 by approximately three-fold in human coding sequences to one cleavage site per ~11 bp. PMID:28581492

Single-particle aerosol mass spectrometry for the detection and identification of chemical warfare agent simulants.

PubMed

Martin, Audrey N; Farquar, George R; Frank, Matthias; Gard, Eric E; Fergenson, David P

2007-08-15

Single-particle aerosol mass spectrometry (SPAMS) was used for the real-time detection of liquid nerve agent simulants. A total of 1000 dual-polarity time-of-flight mass spectra were obtained for micrometer-sized single particles each of dimethyl methyl phosphonate, diethyl ethyl phosphonate, diethyl phosphoramidate, and diethyl phthalate using laser fluences between 0.58 and 7.83 nJ/microm2, and mass spectral variation with laser fluence was studied. The mass spectra obtained allowed identification of single particles of the chemical warfare agent (CWA) simulants at each laser fluence used although lower laser fluences allowed more facile identification. SPAMS is presented as a promising real-time detection system for the presence of CWAs.

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.

Gaseous and particulate composition of fresh and aged emissions of diesel, RME and CNG buses using Chemical Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Psichoudaki, Magda; Le Breton, Michael; Hallquist, Mattias; Watne, Ågot; Hallquist, Asa

2016-04-01

Urban air pollution is becoming a significant global problem, especially for large cities around the world. Traffic emissions contribute significantly to both elevated particle concentrations and to gaseous pollutants in cities. The latter also have the potential of forming more particulate mass via their photochemical oxidation in the atmosphere. The International Agency for Research on Cancer and the US EPA have characterised diesel exhausts as a likely human carcinogen that can also contribute to other health problems. In order to meet the challenges with increased transportation and enhanced greenhouse gas emissions, the European Union have decided on a 10% substitution of traditional fuels in the road transport sector by alternative fuels (e.g. biodiesel, CNG) before the year 2020. However, it is also important to study the influence of fuel switches on other primary pollutants as well as the potential to form secondary aerosol mass. This work focuses on the characterisation of the chemical composition of the gas and the condensed phase of fresh bus emissions during acceleration, in order to mimic the exhaust plume that humans would inhale under realistic conditions. In addition, photochemical aging of the exhaust emissions was achieved by employing a Potential Aerosol Mass (PAM) flow reactor, allowing the characterization of the composition of the corresponding aged emissions. The PAM reactor uses UV lamps and high concentrations of oxidants (OH radicals and O3) to oxidize the organic species present in the chamber. The oxidation that takes place within the reactor can be equivalent to up to one week of atmospheric oxidation. Preliminary tests showed that the oxidation employed in these measurements corresponded to a range from 4 to 8 days in the atmosphere. During June and July 2015, a total of 29 buses, 5 diesel, 13 CNG and 11 RME (rapeseed methyl ester), were tested in two different locations with limited influence from other types of emissions and traffic

Development of sample exchange robot PAM-HC for beamline BL-1A at the photon factory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hiraki, Masahiko, E-mail: masahiko.hiraki@kek.jp; Department of Accelerator Science, SOKENDAI; Matsugaki, Naohiro

A macromolecular crystallography beamline, BL-1A, has been built at the Photon Factory (PF) for low energy experiments and has been operational since 2010. We have installed a sample exchange robot, PAM (PF Automated Mounting system), similar to other macromolecular crystallography beamlines. However, following the installation of a helium chamber to reduce the absorption of the diffraction signal by air, we developed a new sample exchange robot to replace PAM. The new robot, named PAM-HC (Helium Chamber), is designed with the goal of minimizing leakage of helium gas from the chamber. Here, the PAM-HC hardware and the flow of its movementmore » are described. Furthermore, measurements of temperature changes during sample exchange are presented in this paper.« less

Spatial and Temporal Patterns in the Carbon Isotopic Signal of Leaf Wax Aerosols in Continental Air Masses: Linkages with Ecosystem Discrimination

NASA Astrophysics Data System (ADS)

Weber, J.; Conte, M. H.

2006-12-01

Temporal and spatial variations in the concentration and isotopic composition of atmospheric carbon dioxide can be used to estimate the relative magnitudes of the terrestrial and oceanic carbon sinks. An important model parameter is the terrestrial photosynthetic carbon isotopic fractionation of CO2 (Δ), yet estimating Δ over the large spatial scales required by models remains problematic. Epiculticular leaf waxes appear to closely reflect the plant's carbon isotopic discrimination; therefore, the ablated wax aerosols present in well-mixed continental air masses may be used as a proxy to estimate the magnitude of Δ integrated over large (subcontinental) spatial scales. Over the last several years, we have been conducting time-series studies of wax aerosol molecular and isotopic composition at strategically located sites (Maine, northern Alaska, Florida, Bermuda, Barbados) which receive continental air masses passing over major terrestrial biomes (northern temperate/ecotonal boreal forests, tundra, southern US pine/hardwood forests, North American and north African). In this presentation, we describe and contrast patterns of wax aerosol-derived estimates of Δ at these sites. In North American air masses, estimates of Δ range from 14.5-20.5 using the concentration-weighted average δ13C of wax n-acids and from 13.5-19.5 for the wax n-alcohols. Seasonal trends observed in the Florida (southern US) and Bermuda samples (mixed North American air masses) indicate maximum discrimination in early spring and minimum discrimination during the summer dry season. In northern US and high latitude air masses, seasonal trends are less pronounced but in general temporally offset with highest discrimination occurring during late summer. At Barbados, which is dominated by north African air masses passing over regions largely comprised of arid C4 grasslands, estimated Δ for the wax n-acids is significantly lower (14.0-15.5 per mil), consistent with a higher predominance of C4

Seasonal and spatial variability of the OM/OC mass ratios and high regional correlation between oxalic acid and zinc in Chinese urban organic aerosols

NASA Astrophysics Data System (ADS)

Xing, L.; Fu, T.-M.; Cao, J. J.; Lee, S. C.; Wang, G. H.; Ho, K. F.; Cheng, M.-C.; You, C.-F.; Wang, T. J.

2013-04-01

We calculated the organic matter to organic carbon mass ratios (OM/OC mass ratios) in PM2.5 collected from 14 Chinese cities during summer and winter of 2003 and analyzed the causes for their seasonal and spatial variability. The OM/OC mass ratios were calculated two ways. Using a mass balance method, the calculated OM/OC mass ratios averaged 1.92 ± 0.39 year-round, with no significant seasonal or spatial variation. The second calculation was based on chemical species analyses of the organic compounds extracted from the PM2.5 samples using dichloromethane/methanol and water. The calculated OM/OC mass ratio in summer was relatively high (1.75 ± 0.13) and spatially-invariant due to vigorous photochemistry and secondary organic aerosol (OA) production throughout the country. The calculated OM/OC mass ratio in winter (1.59 ± 0.18) was significantly lower than that in summer, with lower values in northern cities (1.51 ± 0.07) than in southern cities (1.65 ± 0.15). This likely reflects the wider usage of coal for heating purposes in northern China in winter, in contrast to the larger contributions from biofuel and biomass burning in southern China in winter. On average, organic matter constituted 36% and 34% of Chinese urban PM2.5 mass in summer and winter, respectively. We report, for the first time, a high regional correlation between Zn and oxalic acid in Chinese urban aerosols in summer. This is consistent with the formation of stable Zn oxalate complex in the aerosol phase previously proposed by Furukawa and Takahashi (2011). We found that many other dicarboxylic acids were also highly correlated with Zn in the summer Chinese urban aerosol samples, suggesting that they may also form stable organic complexes with Zn. Such formation may have profound implications for the atmospheric abundance and hygroscopic properties of aerosol dicarboxylic acids.

60 YEARS OF POMC: From POMC and α-MSH to PAM, molecular oxygen, copper, and vitamin C.

PubMed

Kumar, Dhivya; Mains, Richard E; Eipper, Betty A

2016-05-01

A critical role for peptide C-terminal amidation was apparent when the first bioactive peptides were identified. The conversion of POMC into adrenocorticotropic hormone and then into α-melanocyte-stimulating hormone, an amidated peptide, provided a model system for identifying the amidating enzyme. Peptidylglycine α-amidating monooxygenase (PAM), the only enzyme that catalyzes this modification, is essential; mice lacking PAM survive only until mid-gestation. Purification and cloning led to the discovery that the amidation of peptidylglycine substrates proceeds in two steps: peptidylglycine α-hydroxylating monooxygenase catalyzes the copper- and ascorbate-dependent α-hydroxylation of the peptidylglycine substrate; peptidyl-α-hydroxyglycine α-amidating lyase cleaves the N-C bond, producing amidated product and glyoxylate. Both enzymes are contained in the luminal domain of PAM, a type 1 integral membrane protein. The structures of both catalytic cores have been determined, revealing how they interact with metals, molecular oxygen, and substrate to catalyze both reactions. Although not essential for activity, the intrinsically disordered cytosolic domain is essential for PAM trafficking. A phylogenetic survey led to the identification of bifunctional membrane PAM in Chlamydomonas, a unicellular eukaryote. Accumulating evidence points to a role for PAM in copper homeostasis and in retrograde signaling from the lumen of the secretory pathway to the nucleus. The discovery of PAM in cilia, cellular antennae that sense and respond to environmental stimuli, suggests that much remains to be learned about this ancient protein. © 2016 Society for Endocrinology.

Classification of organic aerosol in the atmosphere over Seoul based on chemical group separation using two dimensional gas chromatography-time of flight mass spectrometry (GC×GC TOFMS) data

NASA Astrophysics Data System (ADS)

Jeon, S.; Lim, H. B.; Choi, N.; Lee, J.; Ahn, Y. K.; Kim, Y. P.

2016-12-01

Organic aerosols contain thousands of organic compounds and contribute to 20-90% of the total fine aerosol mass. For analyzing organic aerosols, a wide range of analytical techniques have been used such as gas chromatography mass spectrometer (GC/MS), liquid chromatography mass spectrometer (LC/MS), aerosol mass spectrometer (AMS), etc. Among them, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometer (GCxGC/TOF-MS) can provide higher chemical resolution than AMS and analyze more mass fractions of organic aerosols than GC/MS. In this study, we suggest a new data processing method using GCxGC/TOF-MS data for analyzing organic compounds in the ambient aerosols. TSP samples were collected on the roof of the Asan engineering building, Ewha Womans University, Seoul, South Korea (37.56 °N, 126.94 °E, 20 m above ground level). A total of 67 samples were obtained during summer (August 2013) and winter (January and February 2014) with a PUF sampler (Tisch, TE-1000) on quartz fiber filter. Filters were extracted using accelerated solvent extractor with a mixture of dichloromethane and methanol (3:1, v/v). Total extracts were blown down to 0.5 mL using a nitrogen evaporator (Turbo Vap Ⅱ, caliper Life Sciences). Organic compounds in the TSP samples were separated into 6 chemical groups, depending on their retention time in two dimensions for their volatility and polarity. All area of peaks in each group was summed and variance of total area in each group was compared depending on season and diurnal cycle.

Particle interactions of fluticasone propionate and salmeterol xinafoate detected with single particle aerosol mass spectrometry (SPAMS).

PubMed

Jetzer, Martin W; Morrical, Bradley D; Fergenson, David P; Imanidis, Georgios

2017-10-30

Particle co-associations between the active pharmaceutical ingredients fluticasone propionate and salmeterol xinafoate were examined in dry powder inhaled (DPI) and metered dose inhaled (MDI) combination products. Single Particle Aerosol Mass Spectrometry was used to investigate the particle interactions in Advair Diskus ® (500/50 mcg) and Seretide ® (125/25 mcg). A simple rules tree was used to identify each compound, either alone or co-associated at the level of the individual particle, using unique marker peaks in the mass spectra for the identification of each drug. High levels of drug particle co-association (fluticasone-salmeterol) were observed in the aerosols emitted from Advair Diskus ® and Seretide ® . The majority of the detected salmeterol particles were found to be in co-association with fluticasone in both tested devices. Another significant finding was that rather coarse fluticasone particles (in DPI) and fine salmeterol particles (both MDI and DPI) were forming the particle co-associations. Copyright © 2017 Elsevier B.V. All rights reserved.

Aerosol generation and measurement of multi-wall carbon nanotubes

NASA Astrophysics Data System (ADS)

Myojo, Toshihiko; Oyabu, Takako; Nishi, Kenichiro; Kadoya, Chikara; Tanaka, Isamu; Ono-Ogasawara, Mariko; Sakae, Hirokazu; Shirai, Tadashi

2009-01-01

Mass production of some kinds of carbon nanotubes (CNT) is now imminent, but little is known about the risk associated with their exposure. It is important to assess the propensity of the CNT to release particles into air for its risk assessment. In this study, we conducted aerosolization of a multi-walled CNT (MWCNT) to assess several aerosol measuring instruments. A Palas RBG-1000 aerosol generator applied mechanical stress to the MWCNT by a rotating brush at feed rates ranging from 2 to 20 mm/h, which the MWCNT was fed to a two-component fluidized bed. The fluidized bed aerosol generator was used to disperse the MWCNT aerosol once more. We monitored the generated MWCNT aerosol concentrations based on number, area, and mass using a condensation particle counter and nanoparticle surface area monitor. Also we quantified carbon mass in MWCNT aerosol samples by a carbon monitor. The shape of aerosolized MWCNT fibers was observed by a scanning electron microscope (SEM). The MWCNT was well dispersed by our system. We found isolated MWCNT fibers in the aerosols by SEM and the count median lengths of MWCNT fibers were 4-6 μm. The MWCNT was quantified by the carbon monitor with a modified condition based on the NIOSH analytical manual. The MWCNT aerosol concentration (EC mass base) was 4 mg/m3 at 2 mm/h in this study.

Relationship between fluid bed aerosol generator operation and the aerosol produced

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carpenter, R.L.; Yerkes, K.

1980-12-01

The relationships between bed operation in a fluid bed aerosol generator and aerosol output were studied. A two-inch diameter fluid bed aerosol generator (FBG) was constructed using stainless steel powder as a fluidizing medium. Fly ash from coal combustion was aerosolized and the influence of FBG operating parameters on aerosol mass median aerodynamic diameter (MMAD), geometric standard deviation (sigma/sub g/) and concentration was examined. In an effort to extend observations on large fluid beds to small beds using fine bed particles, minimum fluidizing velocities and elutriation constant were computed. Although FBG minimum fluidizing velocity agreed well with calculations, FBG elutriationmore » constant did not. The results of this study show that the properties of aerosols produced by a FBG depend on fluid bed height and air flow through the bed after the minimum fluidizing velocity is exceeded.« less

Laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF): performance, reference spectra and classification of atmospheric samples

NASA Astrophysics Data System (ADS)

Shen, Xiaoli; Ramisetty, Ramakrishna; Mohr, Claudia; Huang, Wei; Leisner, Thomas; Saathoff, Harald

2018-04-01

The laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF, AeroMegt GmbH) is able to identify the chemical composition and mixing state of individual aerosol particles, and thus is a tool for elucidating their impacts on human health, visibility, ecosystem, and climate. The overall detection efficiency (ODE) of the instrument we use was determined to range from ˜ (0.01 ± 0.01) to ˜ (4.23 ± 2.36) % for polystyrene latex (PSL) in the size range of 200 to 2000 nm, ˜ (0.44 ± 0.19) to ˜ (6.57 ± 2.38) % for ammonium nitrate (NH4NO3), and ˜ (0.14 ± 0.02) to ˜ (1.46 ± 0.08) % for sodium chloride (NaCl) particles in the size range of 300 to 1000 nm. Reference mass spectra of 32 different particle types relevant for atmospheric aerosol (e.g. pure compounds NH4NO3, K2SO4, NaCl, oxalic acid, pinic acid, and pinonic acid; internal mixtures of e.g. salts, secondary organic aerosol, and metallic core-organic shell particles; more complex particles such as soot and dust particles) were determined. Our results show that internally mixed aerosol particles can result in spectra with new clusters of ions, rather than simply a combination of the spectra from the single components. An exemplary 1-day ambient data set was analysed by both classical fuzzy clustering and a reference-spectra-based classification method. Resulting identified particle types were generally well correlated. We show how a combination of both methods can greatly improve the interpretation of single-particle data in field measurements.

An Archaeal Immune System Can Detect Multiple Protospacer Adjacent Motifs (PAMs) to Target Invader DNA*

PubMed Central

Fischer, Susan; Maier, Lisa-Katharina; Stoll, Britta; Brendel, Jutta; Fischer, Eike; Pfeiffer, Friedhelm; Dyall-Smith, Mike; Marchfelder, Anita

2012-01-01

The clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) system provides adaptive and heritable immunity against foreign genetic elements in most archaea and many bacteria. Although this system is widespread and diverse with many subtypes, only a few species have been investigated to elucidate the precise mechanisms for the defense of viruses or plasmids. Approximately 90% of all sequenced archaea encode CRISPR/Cas systems, but their molecular details have so far only been examined in three archaeal species: Sulfolobus solfataricus, Sulfolobus islandicus, and Pyrococcus furiosus. Here, we analyzed the CRISPR/Cas system of Haloferax volcanii using a plasmid-based invader assay. Haloferax encodes a type I-B CRISPR/Cas system with eight Cas proteins and three CRISPR loci for which the identity of protospacer adjacent motifs (PAMs) was unknown until now. We identified six different PAM sequences that are required upstream of the protospacer to permit target DNA recognition. This is only the second archaeon for which PAM sequences have been determined, and the first CRISPR group with such a high number of PAM sequences. Cells could survive the plasmid challenge if their CRISPR/Cas system was altered or defective, e.g. by deletion of the cas gene cassette. Experimental PAM data were supplemented with bioinformatics data on Haloferax and Haloquadratum. PMID:22767603

The influence of continental air masses on the aerosols and nutrients deposition over the western North Pacific

NASA Astrophysics Data System (ADS)

Fu, Jiangping; Wang, Bo; Chen, Ying; Ma, Qingwei

2018-01-01

The air masses transported from East Asia have a strong impact on the aerosol properties and deposition in the marine boundary layer of the western North Pacific (WNP) during winter and spring. We joined a cruise between 17 Mar. and 22 Apr. 2014 and investigated the changes of aerosol composition and size distribution over the remote WNP and marginal seas. Although the secondary aerosol species (SO42-, NO3- and NH4+) in remote WNP were influenced significantly by the continental transport, NH4+ concentrations were lower than 2.7 μg m-3 in most sampling days and not correlated with non-sea-salt (nss)-SO42- suggesting that the ocean could be a primary source of NH4+. Moderate Cl- depletion (23%) was observed in remote WNP, and the inverse relationship between Cl- depletion percentages and nss-K+ in aerosols suggested that the transport of biomass burning smoke from East Asia might be a vital extra source of Cl-. Both Asian dust and haze events were encountered during the cruise. Asian dust carried large amounts of crustal elements such as Al and Ti to the WNP, and the dusty Fe deposition may double its background concentration in seawater. Differently, a dramatic increase of dry deposition flux of dissolved particulate inorganic nitrogen was observed during the haze event. Our study reveals that the transport of different continental air masses may have distinct biogeochemical impacts on the WNP by increasing the fluxes of different nutrient elements and potentially changing the nutrient stoichiometry.

Chemical characterization and source apportionment of fine particulate matter in Yangzhou, China, using offline aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Li, L.; Ge, X.; Xu, J.; Ye, Z.

2016-12-01

In recent years, Aerodyne Aerosol Mass Spectrometer (AMS) has been widely used for online and real-time monitoring of fine aerosol particles all over the world. However, due to the high cost and complex maintenance, the AMS was typically deployed for short-term intense field measurements, limiting its ability in elucidating the long-term behaviors and dominant sources of regional fine particles (PM2.5). In this study, we collected daily PM2.5 filter samples across a relatively long period (November 2015 to April 2016, in total >100 samples) using a high-volume sampler, in urban Yangzhou - a city in the Yangtze River Delta region, China. These samples were analyzed by using a suite of analytical techniques, for the water-soluble inorganic ions (WSIs), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and total nitrogen (TN), trace metal elements, etc. More importantly, an Aerodyne soot particle aerosol mass spectrometer (SP-AMS) was for the first time introduced for the offline characterization of the PM2.5 samples collected in this region. In particular, Positive matrix factorization was conducted on the SP-AMS determined water-soluble fraction of organic aerosols (WSOA), and three distinct sources were separated, including a primary OA (POA), a less oxygenated OA (LOOA), and a more oxygenated OA (MOOA). Chemical characteristics and evolution processes of these OA subcomponents were further discussed. Our results are useful for the air pollution management in the YRD region, and the technique developed can be applied elsewhere as well.

Characterization of the sources and processes of organic and inorganic aerosols in New York City with a high-resolution time-of-flight aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Sun, Y.-L.; Zhang, Q.; Schwab, J. J.; Demerjian, K. L.; Chen, W.-N.; Bae, M.-S.; Hung, H.-M.; Hogrefe, O.; Frank, B.; Rattigan, O. V.; Lin, Y.-C.

2010-10-01

Submicron aerosol particles (PM1) were measured in-situ using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) during the summer 2009 Field Intensive Study at Queens College in New York City. Organic aerosol (OA) and sulfate are the two dominant species, accounting for 54% and 24%, respectively, of total PM1 mass on average. The average mass size distribution of OA presents a small mode peaking at ~150 nm (Dva) in addition to an accumulation mode (~550 nm) that is internally mixed with sulfate, nitrate, and ammonium. The diurnal cycles of sulfate and OA both show pronounced peaks between 01:00-02:00 p.m. EST due to photochemical production. The average (±1σ) oxygen-to-carbon (O/C), hydrogen-to-carbon (H/C), and nitrogen-to-carbon (N/C) ratios of OA in NYC are 0.36 (±0.09), 1.49 (±0.08), and 0.012(±0.005), respectively, corresponding to an average organic mass-to-carbon (OM/OC) ratio of 1.62(±0.11). Positive matrix factorization (PMF) of the high resolution mass spectra identified five OA components: a hydrocarbon-like OA (HOA), two types of oxygenated OA (OOA) including a low-volatility OOA (LV-OOA) and a semi-volatile OOA (SV-OOA), a cooking-emission related OA (COA), and a unique nitrogen-enriched OA (NOA). HOA appears to represent primary OA (POA) from urban traffic emissions. It comprises primarily of reduced species (H/C=1.83; O/C=0.06) and shows a mass spectral pattern very similar to those of POA from fossil fuel combustion, and correlates tightly with traffic emission tracers including elemental carbon and NOx. LV-OOA, which is highly oxidized (O/C=0.63) and correlates well with sulfate, appears to be representative for regional, aged secondary OA (SOA). SV-OOA, which is less oxidized (O/C=0.38) and correlates well with non-refractory chloride, likely represents less photo-chemically aged, semi-volatile SOA. COA shows a similar spectral pattern to the reference spectra of POA from cooking emissions and a distinct diurnal pattern

Measuring Sodium Chloride Contents of Aerosols

NASA Technical Reports Server (NTRS)

Sinha, M. P.; Friedlander, S. K.

1986-01-01

Amount of sodium chloride in individual aerosol particles measured in real time by analyzer that includes mass spectrometer. Analyzer used to determine mass distributions of active agents in therapeutic or diagnostic aerosols derived from saline solutions and in analyzing ocean spray. Aerosol particles composed of sodium chloride introduced into oven, where individually vaporized on hot wall. Vapor molecules thermally dissociated, and some of resulting sodium atoms ionized on wall. Ions leave oven in burst and analyzed by spectrometer, which is set to monitor sodium-ion intensity.

Ion mobility spectrometry–mass spectrometry (IMS–MS) for on- and offline analysis of atmospheric gas and aerosol species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krechmer, Jordan E.; Groessl, Michael; Zhang, Xuan

Measurement techniques that provide molecular-level information are needed to elucidate the multiphase processes that produce secondary organic aerosol (SOA) species in the atmosphere. Here we demonstrate the application of ion mobility spectrometry-mass spectrometry (IMS–MS) to the simultaneous characterization of the elemental composition and molecular structures of organic species in the gas and particulate phases. Molecular ions of gas-phase organic species are measured online with IMS–MS after ionization with a custom-built nitrate chemical ionization (CI) source. This CI–IMS–MS technique is used to obtain time-resolved measurements (5 min) of highly oxidized organic molecules during the 2013 Southern Oxidant and Aerosol Study (SOAS)more » ambient field campaign in the forested SE US. The ambient IMS–MS signals are consistent with laboratory IMS–MS spectra obtained from single-component carboxylic acids and multicomponent mixtures of isoprene and monoterpene oxidation products. Mass-mobility correlations in the 2-D IMS–MS space provide a means of identifying ions with similar molecular structures within complex mass spectra and are used to separate and identify monoterpene oxidation products in the ambient data that are produced from different chemical pathways. Water-soluble organic carbon (WSOC) constituents of fine aerosol particles that are not resolvable with standard analytical separation methods, such as liquid chromatography (LC), are shown to be separable with IMS–MS coupled to an electrospray ionization (ESI) source. The capability to use ion mobility to differentiate between isomers is demonstrated for organosulfates derived from the reactive uptake of isomers of isoprene epoxydiols (IEPOX) onto wet acidic sulfate aerosol. As a result, controlled fragmentation of precursor ions by collisionally induced dissociation (CID) in the transfer region between the IMS and the MS is used to validate MS peak assignments, elucidate structures

Ion mobility spectrometry–mass spectrometry (IMS–MS) for on- and offline analysis of atmospheric gas and aerosol species

DOE PAGES

Krechmer, Jordan E.; Groessl, Michael; Zhang, Xuan; ...

2016-07-25

Measurement techniques that provide molecular-level information are needed to elucidate the multiphase processes that produce secondary organic aerosol (SOA) species in the atmosphere. Here we demonstrate the application of ion mobility spectrometry-mass spectrometry (IMS–MS) to the simultaneous characterization of the elemental composition and molecular structures of organic species in the gas and particulate phases. Molecular ions of gas-phase organic species are measured online with IMS–MS after ionization with a custom-built nitrate chemical ionization (CI) source. This CI–IMS–MS technique is used to obtain time-resolved measurements (5 min) of highly oxidized organic molecules during the 2013 Southern Oxidant and Aerosol Study (SOAS)more » ambient field campaign in the forested SE US. The ambient IMS–MS signals are consistent with laboratory IMS–MS spectra obtained from single-component carboxylic acids and multicomponent mixtures of isoprene and monoterpene oxidation products. Mass-mobility correlations in the 2-D IMS–MS space provide a means of identifying ions with similar molecular structures within complex mass spectra and are used to separate and identify monoterpene oxidation products in the ambient data that are produced from different chemical pathways. Water-soluble organic carbon (WSOC) constituents of fine aerosol particles that are not resolvable with standard analytical separation methods, such as liquid chromatography (LC), are shown to be separable with IMS–MS coupled to an electrospray ionization (ESI) source. The capability to use ion mobility to differentiate between isomers is demonstrated for organosulfates derived from the reactive uptake of isomers of isoprene epoxydiols (IEPOX) onto wet acidic sulfate aerosol. As a result, controlled fragmentation of precursor ions by collisionally induced dissociation (CID) in the transfer region between the IMS and the MS is used to validate MS peak assignments, elucidate structures

Ion mobility spectrometry-mass spectrometry (IMS-MS) for on- and offline analysis of atmospheric gas and aerosol species

NASA Astrophysics Data System (ADS)

Krechmer, Jordan E.; Groessl, Michael; Zhang, Xuan; Junninen, Heikki; Massoli, Paola; Lambe, Andrew T.; Kimmel, Joel R.; Cubison, Michael J.; Graf, Stephan; Lin, Ying-Hsuan; Budisulistiorini, Sri H.; Zhang, Haofei; Surratt, Jason D.; Knochenmuss, Richard; Jayne, John T.; Worsnop, Douglas R.; Jimenez, Jose-Luis; Canagaratna, Manjula R.

2016-07-01

Measurement techniques that provide molecular-level information are needed to elucidate the multiphase processes that produce secondary organic aerosol (SOA) species in the atmosphere. Here we demonstrate the application of ion mobility spectrometry-mass spectrometry (IMS-MS) to the simultaneous characterization of the elemental composition and molecular structures of organic species in the gas and particulate phases. Molecular ions of gas-phase organic species are measured online with IMS-MS after ionization with a custom-built nitrate chemical ionization (CI) source. This CI-IMS-MS technique is used to obtain time-resolved measurements (5 min) of highly oxidized organic molecules during the 2013 Southern Oxidant and Aerosol Study (SOAS) ambient field campaign in the forested SE US. The ambient IMS-MS signals are consistent with laboratory IMS-MS spectra obtained from single-component carboxylic acids and multicomponent mixtures of isoprene and monoterpene oxidation products. Mass-mobility correlations in the 2-D IMS-MS space provide a means of identifying ions with similar molecular structures within complex mass spectra and are used to separate and identify monoterpene oxidation products in the ambient data that are produced from different chemical pathways. Water-soluble organic carbon (WSOC) constituents of fine aerosol particles that are not resolvable with standard analytical separation methods, such as liquid chromatography (LC), are shown to be separable with IMS-MS coupled to an electrospray ionization (ESI) source. The capability to use ion mobility to differentiate between isomers is demonstrated for organosulfates derived from the reactive uptake of isomers of isoprene epoxydiols (IEPOX) onto wet acidic sulfate aerosol. Controlled fragmentation of precursor ions by collisionally induced dissociation (CID) in the transfer region between the IMS and the MS is used to validate MS peak assignments, elucidate structures of oligomers, and confirm the

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

PubMed

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

2009-03-01

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

Development and first application of an Aerosol Collection Module (ACM) for quasi online compound specific aerosol measurements

NASA Astrophysics Data System (ADS)

Hohaus, Thorsten; Kiendler-Scharr, Astrid; Trimborn, Dagmar; Jayne, John; Wahner, Andreas; Worsnop, Doug

2010-05-01

Atmospheric aerosols influence climate and human health on regional and global scales (IPCC, 2007). In many environments organics are a major fraction of the aerosol influencing its properties. Due to the huge variety of organic compounds present in atmospheric aerosol current measurement techniques are far from providing a full speciation of organic aerosol (Hallquist et al., 2009). The development of new techniques for compound specific measurements with high time resolution is a timely issue in organic aerosol research. Here we present first laboratory characterisations of an aerosol collection module (ACM) which was developed to allow for the sampling and transfer of atmospheric PM1 aerosol. The system consists of an aerodynamic lens system focussing particles on a beam. This beam is directed to a 3.4 mm in diameter surface which is cooled to -30 °C with liquid nitrogen. After collection the aerosol sample can be evaporated from the surface by heating it to up to 270 °C. The sample is transferred through a 60cm long line with a carrier gas. In order to test the ACM for linearity and sensitivity we combined it with a GC-MS system. The tests were performed with octadecane aerosol. The octadecane mass as measured with the ACM-GC-MS was compared versus the mass as calculated from SMPS derived total volume. The data correlate well (R2 0.99, slope of linear fit 1.1) indicating 100 % collection efficiency. From 150 °C to 270 °C no effect of desorption temperature on transfer efficiency could be observed. The ACM-GC-MS system was proven to be linear over the mass range 2-100 ng and has a detection limit of ~ 2 ng. First experiments applying the ACM-GC-MS system were conducted at the Jülich Aerosol Chamber. Secondary organic aerosol (SOA) was formed from ozonolysis of 600 ppbv of b-pinene. The major oxidation product nopinone was detected in the aerosol and could be shown to decrease from 2 % of the total aerosol to 0.5 % of the aerosol over the 48 hours of

Comparison of the impact of volcanic eruptions and aircraft emissions on the aerosol mass loading and sulfur budget in the stratosphere

NASA Technical Reports Server (NTRS)

Yue, Glenn K.; Poole, Lamont R.

1992-01-01

Data obtained by the Stratospheric Aerosol and Gas Experiment (SAGE) 1 and 2 were used to study the temporal variation of aerosol optical properties and to assess the mass loading of stratospheric aerosols from the eruption of volcanos Ruiz and Kelut. It was found that the yearly global average of optical depth at 1.0 micron for stratospheric background aerosols in 1979 was 1.16 x 10(exp -3) and in 1989 was 1.66 x 10(exp -3). The eruptions of volcanos Ruiz and Kelut ejected at least 5.6 x 10(exp 5) and 1.8 x 10(exp 5) tons of materials into the stratosphere, respectively. The amount of sulfur emitted per year from the projected subsonic and supersonic fleet is comparable to that contained in the background aerosol particles in midlatitudes from 35 deg N to 55 deg N.

Ubiquitous influence of wildfire emissions and secondary organic aerosol on summertime atmospheric aerosol in the forested Great Lakes region

NASA Astrophysics Data System (ADS)

Gunsch, Matthew J.; May, Nathaniel W.; Wen, Miao; Bottenus, Courtney L. H.; Gardner, Daniel J.; VanReken, Timothy M.; Bertman, Steven B.; Hopke, Philip K.; Ault, Andrew P.; Pratt, Kerri A.

2018-03-01

Long-range aerosol transport affects locations hundreds of kilometers from the point of emission, leading to distant particle sources influencing rural environments that have few major local sources. Source apportionment was conducted using real-time aerosol chemistry measurements made in July 2014 at the forested University of Michigan Biological Station near Pellston, Michigan, a site representative of the remote forested Great Lakes region. Size-resolved chemical composition of individual 0.5-2.0 µm particles was measured using an aerosol time-of-flight mass spectrometer (ATOFMS), and non-refractory aerosol mass less than 1 µm (PM1) was measured with a high-resolution aerosol mass spectrometer (HR-AMS). The field site was influenced by air masses transporting Canadian wildfire emissions and urban pollution from Milwaukee and Chicago. During wildfire-influenced periods, 0.5-2.0 µm particles were primarily aged biomass burning particles (88 % by number). These particles were heavily coated with secondary organic aerosol (SOA) formed during transport, with organics (average O/C ratio of 0.8) contributing 89 % of the PM1 mass. During urban-influenced periods, organic carbon, elemental carbon-organic carbon, and aged biomass burning particles were identified, with inorganic secondary species (ammonium, sulfate, and nitrate) contributing 41 % of the PM1 mass, indicative of atmospheric processing. With current models underpredicting organic carbon in this region and biomass burning being the largest combustion contributor to SOA by mass, these results highlight the importance for regional chemical transport models to accurately predict the impact of long-range transported particles on air quality in the upper Midwest, United States, particularly considering increasing intensity and frequency of Canadian wildfires.

Linking biogenic hydrocarbons to biogenic aerosol in the Borneo rainforest

NASA Astrophysics Data System (ADS)

Hamilton, J. F.; Alfarra, M. R.; Robinson, N.; Ward, M. W.; Lewis, A. C.; McFiggans, G. B.; Coe, H.; Allan, J. D.

2013-11-01

Emissions of biogenic volatile organic compounds are though to contribute significantly to secondary organic aerosol formation in the tropics, but understanding these transformation processes has proved difficult, due to the complexity of the chemistry involved and very low concentrations. Aerosols from above a Southeast Asian tropical rainforest in Borneo were characterised using liquid chromatography-ion trap mass spectrometry, high-resolution aerosol mass spectrometry and Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) techniques. Oxygenated compounds were identified in ambient organic aerosol that could be directly traced back to isoprene, monoterpenes and sesquiterpene emissions, by combining field data on chemical structures with mass spectral data generated from synthetically produced products created in a simulation chamber. Eighteen oxygenated species of biogenic origin were identified in the rainforest aerosol from the precursors isoprene, α-pinene, limonene, α-terpinene and β-caryophyllene. The observations provide the unambiguous field detection of monoterpene and sesquiterpene oxidation products in SOA above a pristine tropical rainforest. The presence of 2-methyl tetrol organosulfates and an associated sulfated dimer provides direct evidence that isoprene in the presence of sulfate aerosol can make a contribution to biogenic organic aerosol above tropical forests. High-resolution mass spectrometry indicates that sulfur can also be incorporated into oxidation products arising from monoterpene precursors in tropical aerosol.

Linking biogenic hydrocarbons to biogenic aerosol in the Borneo rainforest

NASA Astrophysics Data System (ADS)

Hamilton, J. F.; Alfarra, M. R.; Robinson, N.; Ward, M. W.; Lewis, A. C.; McFiggans, G. B.; Coe, H.; Allan, J. D.

2013-07-01

Emissions of biogenic volatile organic compounds are though to contribute significantly to secondary organic aerosol formation in the tropics, but understanding the process of these transformations has proved difficult, due to the complexity of the chemistry involved and very low concentrations. Aerosols from above a South East Asian tropical rainforest in Borneo were characterised using liquid chromatography-ion trap mass spectrometry, high resolution aerosol mass spectrometry and fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) techniques. Oxygenated compounds were identified in ambient organic aerosol that could be directly traced back to isoprene, monoterpenes and sesquiterpene emissions, by combining field data on chemical structures with mass spectral data generated from synthetically produced products created in a simulation chamber. Eighteen oxygenated species of biogenic origin were identified in the rainforest aerosol from the precursors isoprene, α-pinene, limonene, α-terpinene and β-caryophyllene. The observations provide the unambiguous field detection of monoterpene and sesquiterpene oxidation products in SOA above a pristine tropical rainforest. The presence of 2-methyltetrol organosulfates and an associated sulfated dimer provides direct evidence that isoprene in the presence of sulfate aerosol can make a contribution to biogenic organic aerosol above tropical forests. High-resolution mass spectrometry indicates that sulfur can also be incorporated into oxidation products arising from monoterpene precursors in tropical aerosol.

Chemical Composition of African Biomass Burning Aerosols Over the Southeast Atlantic: Aerosol Mass Spectrometer Results from the 2016 and 2017 ORACLES Field Campaigns.

NASA Astrophysics Data System (ADS)

Dobracki, A. N.; Howell, S. G.; Freitag, S.; Smirnow, N.; Podolske, J. R.

2017-12-01

Biomass burning (BB) is one of the largest contributors of anthropogenic aerosols in the atmosphere. During BB events, organic and inorganic gases and particles are emitted into the atmosphere. Because of their abundance, particle size, and radiative properties, BB aerosols play an important role in global climate. Southern Africa produces 30% of the Earth's BB aerosol particles. Organics, Nitrates, sulfates, and refractory black carbon, along with other chemical species are lofted into the free troposphere and transported over the Southeast Atlantic Ocean. However, considerate uncertainty remains in the chemical composition of these plumes with its large variety of organic and inorganic species. As part of the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) 2016 and 2017 airborne field campaigns, an Aerosol Mass Spectrometer (AMS) was used to sample the chemical composition and chemical structure of the aerosol in this region. Results show constant vertical stratification within the plume over the course of the campaign (August 2017 / September 2016). Using nitrate (NO3) and organic carbon (OC) as two tracers, the structure of the September 2016 plume had a ratio of 1:8 (NO3:OC) in the upper plume (3km-5km), while the lower plume (1km-2.5km) had a ratio of 1:12 (NO3:OC). AMS measurements were supported by carbon monoxide (CO) and carbon dioxide (CO2) measurements. This data revealed a modified combustion efficiency (MCE= ΔCO2/ΔCO2 + ΔCO) of <0.97 in the upper plume, and a higher MCE > 0.97 in the lower plume. An MCE above 0.9 represents efficient burning processes. Additionally, concentrations of C2(H2O)2 (m/z60), a common chemical fragment from breaking up carbohydrates (primarily levoglucosan) emitted by burning biomass only represented <1% of total organics throughout the campaign. These low concentrations are due to efficient combustion rather than oxidation during transport. These results are consistent with earlier studies of

Effective PCR-based detection of Naegleria fowleri from cultured sample and PAM-developed mouse.

PubMed

Kang, Heekyoung; Seong, Gi-Sang; Sohn, Hae-Jin; Kim, Jong-Hyun; Lee, Sang-Eun; Park, Mi Yeoun; Lee, Won-Ja; Shin, Ho-Joon

2015-10-01

Increasing numbers of Primary Amoebic Meningoencephalitis (PAM) cases due to Naegleria fowleri are becoming a serious issue in subtropical and tropical countries as a Neglected Tropical Disease (NTD). To establish a rapid and effective diagnostic tool, a PCR-based detection technique was developed based on previous PCR methods. Four kinds of primer pairs, Nfa1, Nae3, Nf-ITS, and Naegl, were employed in the cultured amoebic trophozoites and a mouse with PAM experimentally developed by N. fowleri inoculation (PAM-mouse). For the extraction of genomic DNA from N. fowleri trophozoites (1×10(6)), simple boiling with 10μl of PBS (pH 7.4) at 100°C for 30min was found to be the most rapid and efficient procedure, allowing amplification of 2.5×10(2) trophozoites using the Nfa-1 primer. The primers Nfa1 and Nae3 amplified only N. fowleri DNA, whereas the ITS primer detected N. fowleri and N. gruberi DNA. Using the PAM-mouse brain tissue, the Nfa1 primer was able to amplify the N. fowleri DNA 4 days post infection with 1ng/μl of genomic DNA being detectable. Using the PAM-mouse CSF, amplification of the N. fowleri DNA with the Nae3 primer was possible 5 days post infection showing a better performance than the Nfa1 primer at day 6. Copyright © 2015 Elsevier GmbH. All rights reserved.

Determination of particulate lead during MILAGRO / MCMA-2006 using Aerosol Mass Spectrometry

NASA Astrophysics Data System (ADS)

Salcedo, Dara; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; de Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L.

2010-05-01

We report the first measurements of particulate lead (Pb) from Aerodyne Aerosol Mass Spectrometers, which were deployed in and around Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO) / Mexico City Metropolitan Area 2006 (MCMA-2006) field campaigns. The high resolution mass spectrometer of one of the AMS instruments (HR-AMS) and the measured isotopic ratios unequivocally prove the detection of Pb in ambient particles. A substantial fraction of the lead evaporated slowly from the vaporizer of the instruments, which is indicative of species with low volatility at 600oC. A model was developed in order to estimate the ambient particulate Pb entering the AMS from the signals in the "open" and the "closed" (or "background") mass spectrum modes of the AMS. The model suggests the presence of at least two lead fractions with ~25% of the Pb signal exhibiting rapid evaporation (1/e decay constant, τ < 0.1 s) and ~75% exhibiting slow evaporation (τ ~2.4 min) at T0 and a different fraction (70% prompt and 30% slow evaporation) at a site northwest from the metropolitan area (PEMEX32 site). From laboratory experiments with pure Pb(NO3)2 particles, we estimated that the Pb ionization efficiency relative to nitrate (RIEPb) is 0.5. Comparison of time series of AMS Pb with other measurements carried out at the T0 urban supersite during MILAGRO (using Proton Induced X-ray Emission (PIXE), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and single-particle counts from an Aerosol Time-of-Fight Mass Spectrometer (ATOFMS)) shows similar levels (for PIXE and ICP-MS) and substantial correlation. During part of the campaign, sampling at T0 was alternated every 10 minutes with an Aerosol Concentrator, which enabled the detection of signals for PbCl+ and PbS+ ions. PbS+ displays the signature of a slowly evaporating species, while PbCl+ appears to arise only from fast evaporation, which is likely due to the higher vapor pressure of the

Effects of miso- and mesoscale obstructions on PAM winds obtained during project NIMROD. [Portable Automated Mesonet

NASA Technical Reports Server (NTRS)

Fujita, T. T.; Wakimoto, R. M.

1982-01-01

Data from 27 PAM (Portable Automated Mesonet) stations, operational as a phase of project NIMROD (Northern Illinois Meteorological Research on Downburst), are presented. It was found that PAM-measured winds are influenced by the mesoscale obstruction of the Chicago metropolitan area, as well as by the misoscale obstruction of identified trees and buildings. The mesoscale obstruction was estimated within the range of near zero to 50%, increasing toward the city limits, while the misoscale obstruction was estimated as being as large as 58% near obstructing trees which were empirically calculated to cause a wind speed deficit 50-80 times their height. Despite a statistical analysis based on one-million PAM winds, wind speed and stability transmission factors could not be accurately calculated; thus, in order to calculate the airflow free from obstacle, PAM-measured winds must be corrected.

Seven years of aerosol scattering hygroscopic growth measurements from SGP: Factors influencing water uptake: Aerosol Scattering Hygroscopic Growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jefferson, A.; Hageman, D.; Morrow, H.

Long-term measurements of changes in the aerosol scattering coefficient hygroscopic growth at the U.S. Department of Energy Southern Great Plains site provide information on the seasonal as well as size and chemical dependence of aerosol water uptake. Annual average sub-10 μm fRH values (the ratio of aerosol scattering at 85%/40% relative humidity (RH)) were 1.78 and 1.99 for the gamma and kappa fit algorithms, respectively. Our study found higher growth rates in the winter and spring seasons that correlated with a high aerosol nitrate mass fraction. fRH exhibited strong, but differing, correlations with the scattering Ångström exponent and backscatter fraction,more » two optical size-dependent parameters. The aerosol organic mass fraction had a strong influence on fRH. Increases in the organic mass fraction and absorption Ångström exponent coincided with a decrease in fRH. Similarly, fRH declined with decreases in the aerosol single scatter albedo. The uncertainty analysis of the fit algorithms revealed high uncertainty at low scattering coefficients and increased uncertainty at high RH and fit parameters values.« less

Seven years of aerosol scattering hygroscopic growth measurements from SGP: Factors influencing water uptake: Aerosol Scattering Hygroscopic Growth

DOE PAGES

Jefferson, A.; Hageman, D.; Morrow, H.; ...

2017-09-11

Long-term measurements of changes in the aerosol scattering coefficient hygroscopic growth at the U.S. Department of Energy Southern Great Plains site provide information on the seasonal as well as size and chemical dependence of aerosol water uptake. Annual average sub-10 μm fRH values (the ratio of aerosol scattering at 85%/40% relative humidity (RH)) were 1.78 and 1.99 for the gamma and kappa fit algorithms, respectively. Our study found higher growth rates in the winter and spring seasons that correlated with a high aerosol nitrate mass fraction. fRH exhibited strong, but differing, correlations with the scattering Ångström exponent and backscatter fraction,more » two optical size-dependent parameters. The aerosol organic mass fraction had a strong influence on fRH. Increases in the organic mass fraction and absorption Ångström exponent coincided with a decrease in fRH. Similarly, fRH declined with decreases in the aerosol single scatter albedo. The uncertainty analysis of the fit algorithms revealed high uncertainty at low scattering coefficients and increased uncertainty at high RH and fit parameters values.« less

Characterization of a real-time tracer for Isoprene Epoxydiols-derived Secondary Organic Aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

NASA Astrophysics Data System (ADS)

Hu, W. W.; Campuzano-Jost, P.; Palm, B. B.; Day, D. A.; Ortega, A. M.; Hayes, P. L.; Krechmer, J. E.; Chen, Q.; Kuwata, M.; Liu, Y. J.; de Sá, S. S.; Martin, S. T.; Hu, M.; Budisulistiorini, S. H.; Riva, M.; Surratt, J. D.; St. Clair, J. M.; Isaacman-Van Wertz, G.; Yee, L. D.; Goldstein, A. H.; Carbone, S.; Artaxo, P.; de Gouw, J. A.; Koss, A.; Wisthaler, A.; Mikoviny, T.; Karl, T.; Kaser, L.; Jud, W.; Hansel, A.; Docherty, K. S.; Robinson, N. H.; Coe, H.; Allan, J. D.; Canagaratna, M. R.; Paulot, F.; Jimenez, J. L.

2015-04-01

Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene low-NO oxidation pathways, was quantified by applying Positive Matrix Factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of OA in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the SOAS study, 78% of IEPOX-SOA is accounted for the measured molecular tracers, making it the highest level of molecular identification of an ambient SOA component to our knowledge. Enhanced signal at C5H6O+ (m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine fC5H6O ( fC5H6O = C5H6O+/OA) across multiple field, chamber and source datasets. A background of ~ 1.7 ± 0.1‰ is observed in studies strongly influenced by urban, biomass-burning and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.8‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7‰). Locations strongly influenced by isoprene emissions under low-NO levels had higher fC5H6O (~ 6.5 ± 2.2‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. fC5H6O in IEPOX-SOA is always elevated (12-40‰) but varies substantially between locations, which is shown to reflect large variations in its detailed molecular composition. The low fC5H6O (< 3‰) observed in non IEPOX-derived isoprene-SOA indicates that this tracer ion is specifically enhanced from IEPOX-SOA, and is not a tracer for all SOA from

Toward Quantifying the Mass-Based Hygroscopicity of Individual Submicron Atmospheric Aerosol Particles with STXM/NEXAFS and SEM/EDX

NASA Astrophysics Data System (ADS)

Yancey Piens, D.; Kelly, S. T.; OBrien, R. E.; Wang, B.; Petters, M. D.; Laskin, A.; Gilles, M. K.

2014-12-01

The hygroscopic behavior of atmospheric aerosols influences their optical and cloud-nucleation properties, and therefore affects climate. Although changes in particle size as a function of relative humidity have often been used to quantify the hygroscopic behavior of submicron aerosol particles, it has been noted that calculations of hygroscopicity based on size contain error due to particle porosity, non-ideal volume additivity and changes in surface tension. We will present a method to quantify the hygroscopic behavior of submicron aerosol particles based on changes in mass, rather than size, as a function of relative humidity. This method results from a novel experimental approach combining scanning transmission x-ray microscopy with near-edge x-ray absorption fine spectroscopy (STXM/NEXAFS), as well as scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDX) on the same individual particles. First, using STXM/NEXAFS, our methods are applied to aerosol particles of known composition ‒ for instance ammonium sulfate, sodium bromide and levoglucosan ‒ and validated by theory. Then, using STXM/NEXAFS and SEM/EDX, these methods are extended to mixed atmospheric aerosol particles collected in the field at the DOE Atmospheric Radiation Measurement (ARM) Climate Research Facility at the Southern Great Planes sampling site in Oklahoma, USA. We have observed and quantified a range of hygroscopic behaviors which are correlated to the composition and morphology of individual aerosol particles. These methods will have implications for parameterizing aerosol mixing state and cloud-nucleation activity in atmospheric models.

Comparison of MADE3-simulated and observed aerosol distributions with a focus on aerosol vertical profiles

NASA Astrophysics Data System (ADS)

Kaiser, Christopher; Hendricks, Johannes; Righi, Mattia; Jöckel, Patrick

2016-04-01

The reliability of aerosol radiative forcing estimates from climate models depends on the accuracy of simulated global aerosol distribution and composition, as well as on the models' representation of the aerosol-cloud and aerosol-radiation interactions. To help improve on previous modeling studies, we recently developed the new aerosol microphysics submodel MADE3 that explicitly tracks particle mixing state in the Aitken, accumulation, and coarse mode size ranges. We implemented MADE3 into the global atmospheric chemistry general circulation model EMAC and evaluated it by comparison of simulated aerosol properties to observations. Compared properties include continental near-surface aerosol component concentrations and size distributions, continental and marine aerosol vertical profiles, and nearly global aerosol optical depth. Recent studies have shown the specific importance of aerosol vertical profiles for determination of the aerosol radiative forcing. Therefore, our focus here is on the evaluation of simulated vertical profiles. The observational data is taken from campaigns between 1990 and 2011 over the Pacific Ocean, over North and South America, and over Europe. The datasets include black carbon and total aerosol mass mixing ratios, as well as aerosol particle number concentrations. Compared to other models, EMAC with MADE3 yields good agreement with the observations - despite a general high bias of the simulated mass mixing ratio profiles. However, BC concentrations are generally overestimated by many models in the upper troposphere. With MADE3 in EMAC, we find better agreement of the simulated BC profiles with HIPPO data than the multi-model average of the models that took part in the AeroCom project. There is an interesting difference between the profiles from individual campaigns and more "climatological" datasets. For instance, compared to spatially and temporally localized campaigns, the model simulates a more continuous decline in both total

Aerosol growth in Titan's ionosphere.

PubMed

Lavvas, Panayotis; Yelle, Roger V; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J; Wahlund, Jan-Erik; Crary, Frank J; Snowden, Darci

2013-02-19

Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan's upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere.

Aerosol composition and source apportionment in Santiago de Chile

NASA Astrophysics Data System (ADS)

Artaxo, Paulo; Oyola, Pedro; Martinez, Roberto

1999-04-01

Santiago de Chile, São Paulo and Mexico City are Latin American urban areas that suffer from heavy air pollution. In order to study air pollution in Santiago area, an aerosol source apportionment study was designed to measure ambient aerosol composition and size distribution for two downtown sampling sites in Santiago. The aerosol monitoring stations were operated in Gotuzo and Las Condes during July and August 1996. The study employed stacked filter units (SFU) for aerosol sampling, collecting fine mode aerosol (dp<2 μm) and coarse mode aerosol (2Aerosol mass (PM 10 mass of particles smaller than 10 μm) and black carbon concentration were also measured. Particle-Induced X-ray Emission (PIXE) was used to measure the concentration of 22 trace elements at levels below 0.5 ng m -3. Quantitative aerosol source apportionment was performed using Absolute Principal Factor Analysis (APFA). Very high aerosol concentrations were observed (up to 400 μg/m 3 PM 10). The main aerosol particle sources in Santiago are resuspended soil dust and traffic emissions. Coarse particles account for 63% of PM 10 aerosol in Gotuzo and 53% in Las Condes. A major part of this component is resuspended soil dust. In the fine fraction, resuspended soil dust accounts for 15% of fine mass, and the aerosols associated with transportation activities account for a high 64% of the fine particle mass. Sulfate particle is an important component of the aerosol in Santiago, mainly originating from gas-to-particle conversion from SO 2. In the Gotuzo site, sulfates are the highest aerosol component, accounting for 64.5% of fine mass. Direct traffic emissions are generally mixed with resuspended soil dust. It is difficult to separate the two components, because the soil dust in downtown Santiago is contaminated with Pb, Br, Cl, and other heavy metals that are also tracers for traffic emissions. Residual oil combustion is observed, with the presence of V, S and Ni. An

Aerosol Enhancements in the Upper Troposphere Over The Amazon Forest: Do Amazonian Clouds Produce Aerosols?

NASA Astrophysics Data System (ADS)

Andreae, M. O.; Afchine, A.; Albrecht, R. I.; Artaxo, P.; Borrmann, S.; Cecchini, M. A.; Costa, A.; Dollner, M.; Fütterer, D.; Järvinen, E.; Klimach, T.; Konemann, T.; Kraemer, M.; Krüger, M. L.; Machado, L.; Mertes, S.; Pöhlker, C.; Poeschl, U.; Sauer, D. N.; Schnaiter, M.; Schneider, J.; Schulz, C.; Spanu, A.; Walser, A.; Weinzierl, B.; Wendisch, M.

2015-12-01

The German-Brazilian cooperative aircraft campaign ACRIDICON-CHUVA (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems) on the German research aircraft HALO took place over the Amazon Basin in September/October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with trace gases, aerosol particles, and atmospheric radiation. The aircraft was equipped with about 30 remote sensing and in-situ instruments for meteorological, trace gas, aerosol, cloud, precipitation, and solar radiation measurements. Fourteen research flights were conducted during this campaign. Observations during ACRIDICON-CHUVA showed high aerosol concentrations in the upper troposphere (UT) over the Amazon Basin, with concentrations after normalization to standard conditions often exceeding those in the boundary layer (BL). This behavior was consistent between several aerosol metrics, including condensation nuclei (CN), cloud condensation nuclei (CCN), and chemical species mass concentrations. These UT aerosols were different in their composition and size distribution from the aerosol in the BL, making convective transport of particles unlikely as a source. The regions in the immediate outflow of deep convective clouds were found to be depleted in aerosol particles, whereas enhanced aerosol number and mass concentrations were found in UT regions that had experienced outflow from deep convection in the preceding 24-48 hours. This suggests that aerosol production takes place in the UT based on volatile and condensable material brought up by deep convection. Subsequently, downward mixing and transport of upper tropospheric aerosol may be a source of particles to the BL, where they increase in size by the condensation of biogenic volatile organic carbon (BVOC) oxidation products. This may be an important source of aerosol particles in the Amazonian BL, where aerosol nucleation and new

Thermal Extraction–Two-Dimensional Gas Chromatography–Mass Spectrometry with Heart-Cutting for Nitrogen Heterocyclics in Biomass Burning Aerosols

EPA Science Inventory

A thermal extraction-two-dimensional gas chromatography-mass spectrometry (TE-GC-MS) method (with heart-cutting) is developed for quantitatively assessing nitrogen (N-bearing organic species (e.g., pyrrole, pyridine, nitriles, and amines) in aerosols emitted from agricultural fir...

Method for characterization of low molecular weight organic acids in atmospheric aerosols using ion chromatography mass spectrometry.

PubMed

Brent, Lacey C; Reiner, Jessica L; Dickerson, Russell R; Sander, Lane C

2014-08-05

The structural composition of PM2.5 monitored in the atmosphere is usually divided by the analysis of organic carbon, black (also called elemental) carbon, and inorganic salts. The characterization of the chemical composition of aerosols represents a significant challenge to analysts, and studies are frequently limited to determination of aerosol bulk properties. To better understand the potential health effects and combined interactions of components in aerosols, a variety of measurement techniques for individual analytes in PM2.5 need to be implemented. The method developed here for the measurement of organic acids achieves class separation of aliphatic monoacids, aliphatic diacids, aromatic acids, and polyacids. The selective ion monitoring capability of a triple quadropole mass analyzer was frequently capable of overcoming instances of incomplete separations. Standard Reference Material (SRM) 1649b Urban Dust was characterized; 34 organic acids were qualitatively identified, and 6 organic acids were quantified.

Photoactivation mechanism of PAmCherry based on crystal structures of the protein in the dark and fluorescent states.

PubMed

Subach, Fedor V; Malashkevich, Vladimir N; Zencheck, Wendy D; Xiao, Hui; Filonov, Grigory S; Almo, Steven C; Verkhusha, Vladislav V

2009-12-15

Photoactivatable fluorescent proteins (PAFPs) are required for super-resolution imaging of live cells. Recently, the first red PAFP, PAmCherry1, was reported, which complements the photo-activatable GFP by providing a red super-resolution color. PAmCherry1 is originally "dark" but exhibits red fluorescence after UV-violet light irradiation. To define the structural basis of PAmCherry1 photoactivation, we determined its crystal structure in the dark and red fluorescent states at 1.50 A and 1.65 A, respectively. The non-coplanar structure of the chromophore in the dark PAmChery1 suggests the presence of an N-acylimine functionality and a single non-oxidized C(alpha)-C(beta) bond in the Tyr-67 side chain in the cyclized Met-66-Tyr-67-Gly-68 tripeptide. MS data of the chromophore-bearing peptide indicates the loss of 20 Da upon maturation, whereas tandem MS reveals the C(alpha)-N bond in Met-66 is oxidized. These data indicate that PAmCherry1 in the dark state possesses the chromophore N-[(E)-(5-hydroxy-1H-imidazol-2-yl)methylidene]acetamide, which, to our knowledge, has not been previously observed in PAFPs. The photoactivated PAmCherry1 exhibits a non-coplanar anionic DsRed-like chromophore but in the trans configuration. Based on the crystallographic analysis, MS data, and biochemical analysis of the PAmCherry1 mutants, we propose the detailed photoactivation mechanism. In this mechanism, the excited-state PAmCherry1 chromophore acts as the oxidant to release CO(2) molecule from Glu-215 via a Koble-like radical reaction. The Glu-215 decarboxylation directs the carbanion formation resulting in the oxidation of the Tyr-67 C(alpha)-C(beta) bond. The double bond extends the pi-conjugation between the phenolic ring of Tyr-67, the imidazolone, and the N-acylimine, resulting in the red fluorescent chromophore.

The Potential of The Synergy of Sunphotometer and Lidar Data to Validate Vertical Profiles of The Aerosol Mass Concentration Estimated by An Air Quality Model

NASA Astrophysics Data System (ADS)

Siomos, N.; Filioglou, M.; Poupkou, A.; Liora, N.; Dimopoulos, S.; Melas, D.; Chaikovsky, A.; Balis, D. S.

2016-06-01

Vertical profiles of the aerosol mass concentration derived by the Lidar/Radiometer Inversion Code (LIRIC), that uses combined sunphotometer and lidar data, were used in order to validate the aerosol mass concentration profiles estimated by the air quality model CAMx. Lidar and CIMEL measurements performed at the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece (40.5N, 22.9E) from the period 2013-2014 were used in this study.

OFDM and PAM comparison using a high baudrate low resolution IM/DD interface for 400G Ethernet access.

PubMed

André, Nuno Sequeira; Louchet, Hadrien; Filsinger, Volker; Hansen, Erik; Richter, André

2016-05-30

We compare OFDM and PAM for 400G Ethernet based on a 3-bit high baudrate IM/DD interface at 1550nm. We demonstrate 27Gb/s and 32Gb/s transmission over 10km SSMF using OFDM and PAM respectively. We show that capacity can be improved through adaptation/equalization to achieve 42Gb/s and 64Gb/s for OFDM and PAM respectively. Experimental results are used to create realistic simulations to extrapolate the performance of both modulation formats under varied conditions. For the considered interface we found that PAM has the best performance, OFDM is impaired by quantization noise. When the resolution limitation is relaxed, OFDM shows better performance.

Glyoxal contribution to aerosols over Los Angeles

NASA Astrophysics Data System (ADS)

Balcerak, Ernie

2012-01-01

Laboratory and field studies have indicated that glyoxal (chemical formula OCHCHO), an atmospheric oxidation product of isoprene and aromatic compounds, may contribute to secondary organic aerosols in the atmosphere, which can block sunlight and affect atmospheric chemistry. Some aerosols are primary aerosols, emitted directly into the atmosphere, while others are secondary, formed through chemical reactions in the atmosphere. Washenfelder et al. describe in situ glyoxal measurements from Pasadena, Calif., near Los Angeles, made during summer 2010. They used three different methods to calculate the contribution of glyoxal to secondary atmospheric aerosol and found that it is responsible for 0-0.2 microgram per cubic meter, or 0-4%, of the secondary organic aerosol mass. The researchers also compared their results to those of a previous study that calculated the glyoxal contribution to aerosol for Mexico City. Mexico City had higher levels of organic aerosol mass from glyoxal. They suggest that the lower contribution of glyoxal to aerosol concentrations for Los Angeles may be due to differences in the composition or water content of the aerosols above the two cities. (Journal of Geophysical Research-Atmospheres, doi:10.1029/2011JD016314, 2011)

STRAPS v1.0: Evaluating a methodology for predicting electron impact ionisation mass spectra for the aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Topping, David; Allan, James; Alfarra, Rami; Aumont, Bernard

2017-04-01

Our ability to model the chemical and thermodynamic processes that lead to secondary organic aerosol (SOA) formation is thought to be hampered by the complexity of the system. While there are fundamental models now available that can simulate the tens of thousands of reactions thought to take place, validation against experiments is highly challenging. Techniques capable of identifying individual molecules such as chromatography are generally only capable of quantifying a subset of the material present, making it unsuitable for a carbon budget analysis. Integrative analytical methods such as the Aerosol Mass Spectrometer (AMS) are capable of quantifying all mass, but because of their inability to isolate individual molecules, comparisons have been limited to simple data products such as total organic mass and O:C ratio. More detailed comparisons could be made if more of the mass spectral information could be used, but because a discrete inversion of AMS data is not possible, this activity requires a system of predicting mass spectra based on molecular composition. In this proof of concept study, the ability to train supervised methods to predict electron impact ionisation (EI) mass spectra for the AMS is evaluated. Supervised Training Regression for the Arbitrary Prediction of Spectra (STRAPS), is not built from first principles. A methodology is constructed whereby the presence of specific mass-to-charge ratio (m/z) channels are fit as a function of molecular structure before the relative peak height for each channel is similarly fit using a range of regression methods. The widely-used AMS mass spectral database is used as a basis for this, using unit mass resolution spectra of laboratory standards. Key to the fitting process is choice of structural information, or molecular fingerprint. Initial results suggest the generic public 'MACCS' fingerprints provide the most accurate trained model when combined with both decision trees and random forests with median

Classifying aerosol type using in situ surface spectral aerosol optical properties

NASA Astrophysics Data System (ADS)

Schmeisser, Lauren; Andrews, Elisabeth; Ogren, John A.; Sheridan, Patrick; Jefferson, Anne; Sharma, Sangeeta; Kim, Jeong Eun; Sherman, James P.; Sorribas, Mar; Kalapov, Ivo; Arsov, Todor; Angelov, Christo; Mayol-Bracero, Olga L.; Labuschagne, Casper; Kim, Sang-Woo; Hoffer, András; Lin, Neng-Huei; Chia, Hao-Ping; Bergin, Michael; Sun, Junying; Liu, Peng; Wu, Hao

2017-10-01

Knowledge of aerosol size and composition is important for determining radiative forcing effects of aerosols, identifying aerosol sources and improving aerosol satellite retrieval algorithms. The ability to extrapolate aerosol size and composition, or type, from intensive aerosol optical properties can help expand the current knowledge of spatiotemporal variability in aerosol type globally, particularly where chemical composition measurements do not exist concurrently with optical property measurements. This study uses medians of the scattering Ångström exponent (SAE), absorption Ångström exponent (AAE) and single scattering albedo (SSA) from 24 stations within the NOAA/ESRL Federated Aerosol Monitoring Network to infer aerosol type using previously published aerosol classification schemes.Three methods are implemented to obtain a best estimate of dominant aerosol type at each station using aerosol optical properties. The first method plots station medians into an AAE vs. SAE plot space, so that a unique combination of intensive properties corresponds with an aerosol type. The second typing method expands on the first by introducing a multivariate cluster analysis, which aims to group stations with similar optical characteristics and thus similar dominant aerosol type. The third and final classification method pairs 3-day backward air mass trajectories with median aerosol optical properties to explore the relationship between trajectory origin (proxy for likely aerosol type) and aerosol intensive parameters, while allowing for multiple dominant aerosol types at each station.The three aerosol classification methods have some common, and thus robust, results. In general, estimating dominant aerosol type using optical properties is best suited for site locations with a stable and homogenous aerosol population, particularly continental polluted (carbonaceous aerosol), marine polluted (carbonaceous aerosol mixed with sea salt) and continental dust/biomass sites

Can Condensing Organic Aerosols Lead to Less Cloud Particles?

NASA Astrophysics Data System (ADS)

Gao, C. Y.; Tsigaridis, K.; Bauer, S.

2017-12-01

We examined the impact of condensing organic aerosols on activated cloud number concentration in a new aerosol microphysics box model, MATRIX-VBS. The model includes the volatility-basis set (VBS) framework in an aerosol microphysical scheme MATRIX (Multiconfiguration Aerosol TRacker of mIXing state) that resolves aerosol mass and number concentrations and aerosol mixing state. Preliminary results show that by including the condensation of organic aerosols, the new model (MATRIX-VBS) has less activated particles compared to the original model (MATRIX), which treats organic aerosols as non-volatile. Parameters such as aerosol chemical composition, mass and number concentrations, and particle sizes which affect activated cloud number concentration are thoroughly evaluated via a suite of Monte-Carlo simulations. The Monte-Carlo simulations also provide information on which climate-relevant parameters play a critical role in the aerosol evolution in the atmosphere. This study also helps simplifying the newly developed box model which will soon be implemented in the global model GISS ModelE as a module.

PAM multiplicity marks genomic target sites as inhibitory to CRISPR-Cas9 editing.

PubMed

Malina, Abba; Cameron, Christopher J F; Robert, Francis; Blanchette, Mathieu; Dostie, Josée; Pelletier, Jerry

2015-12-08

In CRISPR-Cas9 genome editing, the underlying principles for selecting guide RNA (gRNA) sequences that would ensure for efficient target site modification remain poorly understood. Here we show that target sites harbouring multiple protospacer adjacent motifs (PAMs) are refractory to Cas9-mediated repair in situ. Thus we refine which substrates should be avoided in gRNA design, implicating PAM density as a novel sequence-specific feature that inhibits in vivo Cas9-driven DNA modification.

Structural analysis of aerosol particles by microscopic observation using a time-of-flight secondary ion mass spectrometer

NASA Astrophysics Data System (ADS)

Takami, Akinori; Mayama, Norihito; Sakamoto, Tetsuo; Ohishi, Kenji; Irei, Satoshi; Yoshino, Ayako; Hatakeyama, Shiro; Murano, Kentaro; Sadanaga, Yasuhiro; Bandow, Hiroshi; Misawa, Kentaro; Fujii, Masaaki

2013-06-01

The chemical composition and structure of fine aerosol particles with diameters of less than 1 µm were analyzed in the spring of 2011 at Fukue Island, Japan, using an aerosol quadrupole mass spectrometer (Q-AMS, Aerodyne Research, Inc.) and a time-of-flight secondary ion mass spectrometer (TOF-SIMS). The Q-AMS results were similar to those of previous studies conducted at the same location, suggesting that the composition we observed is typical of this site. Based on the TOF-SIMS results, we classified the fine aerosol particles into three types: Type A, in which sulfate was covered with organic matter (OM); Type B, in which soil-containing particles with a diameter of 0.5 µm were associated with sulfate and OM; and Type C, in which black carbon (BC) and sulfate aggregates were associated with OM. During the observation period, the relative abundances of Type A, B, and C particles were 55%, 20%, and 25%, respectively. The structure, chemical composition, and the proportion of each type of particles provide information for a more representative particle model in radiative models. The relative abundance of Type C, i.e., BC-containing particles, is quite different to that in Tokyo, suggesting that Type C could be an indicator of transboundary air pollution, in this case from mainland China.

Origin of atmospheric aerosols at the Pierre Auger Observatory using studies of air mass trajectories in South America

NASA Astrophysics Data System (ADS)

Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antičić, T.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bardenet, R.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Foerster, N.; Fox, B. D.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giammarchi, M.; Giller, M.; Gitto, J.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kadija, K.; Kambeitz, O.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Pȩkala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Pontz, M.; Porcelli, A.; Preda, T.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Straub, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Taşcău, O.; Thao, N. T.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Tridapalli, D. B.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Curci, G.

2014-11-01

The Pierre Auger Observatory is making significant contributions towards understanding the nature and origin of ultra-high energy cosmic rays. One of its main challenges is the monitoring of the atmosphere, both in terms of its state variables and its optical properties. The aim of this work is to analyse aerosol optical depth τa(z) values measured from 2004 to 2012 at the observatory, which is located in a remote and relatively unstudied area of Pampa Amarilla, Argentina. The aerosol optical depth is in average quite low - annual mean τa(3.5 km) ∼ 0.04 - and shows a seasonal trend with a winter minimum - τa(3.5 km) ∼ 0.03 -, and a summer maximum - τa(3.5 km) ∼ 0.06 -, and an unexpected increase from August to September - τa(3.5 km) ∼ 0.055. We computed backward trajectories for the years 2005 to 2012 to interpret the air mass origin. Winter nights with low aerosol concentrations show air masses originating from the Pacific Ocean. Average concentrations are affected by continental sources (wind-blown dust and urban pollution), whilst the peak observed in September and October could be linked to biomass burning in the northern part of Argentina or air pollution coming from surrounding urban areas.

Molecular composition of boreal forest aerosol from Hyytiälä, Finland, using ultrahigh resolution mass spectrometry.

PubMed

Kourtchev, Ivan; Fuller, Stephen; Aalto, Juho; Ruuskanen, Taina M; McLeod, Matthew W; Maenhaut, Willy; Jones, Rod; Kulmala, Markku; Kalberer, Markus

2013-05-07

Organic compounds are important constituents of fine particulate matter (PM) in the troposphere. In this study, we applied direct infusion nanoelectrospray (nanoESI) ultrahigh resolution mass spectrometry (UHR-MS) and liquid chromatography LC/ESI-UHR-MS for the analysis of the organic fraction of PM1 aerosol samples collected over a two week period at a boreal forest site (Hyytiälä), southern Finland. Elemental formulas (460-730 in total) were identified with nanoESI-UHR-MS in the negative ionization mode and attributed to organic compounds with a molecular weight below 400. Kendrick Mass Defect and Van Krevelen approaches were used to identify compound classes and mass distributions of the detected species. The molecular composition of the aerosols strongly varied between samples with different air mass histories. An increased number of nitrogen, sulfur, and highly oxygenated organic compounds was observed during the days associated with continental air masses. However, the samples with Atlantic air mass history were marked by a presence of homologous series of unsaturated and saturated C12-C20 fatty acids suggesting their marine origin. To our knowledge, we show for the first time that the highly detailed chemical composition obtained from UHR-MS analyses can be clearly linked to meteorological parameters and trace gases concentrations that are relevant to atmospheric oxidation processes. The additional LC/ESI-UHR-MS analysis revealed 29 species, which were mainly attributed to oxidation products of biogenic volatile compounds BVOCs (i.e., α,β-pinene, Δ3-carene, limonene, and isoprene) supporting the results from the direct infusion analysis.

Evolution of size-segregated aerosol mass concentration during the Antarctic summer at Northern Foothills, Victoria Land

NASA Astrophysics Data System (ADS)

Illuminati, Silvia; Bau, Sébastien; Annibaldi, Anna; Mantini, Caterina; Libani, Giulia; Truzzi, Cristina; Scarponi, Giuseppe

2016-01-01

Within the framework of the Italian National Programm for Antarctic Research (PNRA), the first direct gravimetric measurements of size-segregated aerosol fractions were carried out at Faraglione Camp, ˜3-km far from the Italian station "M. Zucchelli" (Terra Nova Bay, Ross Sea), during the 2014-2015 austral summer. A six-stage high-volume cascade impactor with size classes between 10 μm and 0.49 μm, and, in parallel, for comparison purposes, a PM10 high-volume sampler (50% cut-off aerodynamic diameter of 10 μm) were used. A 10-day sampling strategy was adopted. Aerosol mass measurements were carried out before and after exposure by using a microbalance specifically designed for the filter weight and placed inside a glove bag in order to maintain stable temperature and humidity conditions during weighing sessions. Measured atmospheric concentrations (referred to the "actual air conditions" of mean temperature of 268 K and mean pressure of 975 hPa) of size-segregated aerosol fractions showed the following values, given as size range, means (interquartile range): Dp < 0.49 μm, 0.33 (0.26-0.34) μg m-3; 0.49-0.95 μm, 0.20 (0.19-0.24) μg m-3; 0.95-1.5 μm, 0.16 (0.13-0.21) μg m-3; 1.5-3.0 μm 0.075 (0.05-0.11) μg m-3; 3.0-7.2 μm 0.12 (0.02-0.19) μg m-3; 7.2-10 μm 0.06 (0.01-0.03) μg m-3. The average mass concentration of the total PM10 at Faraglione Camp for the entire sampling period was 0.92 (0.67-1.1) μg m-3. Although a great variability, the aerosol mass concentration showed a tri-modal distribution, with an accumulation mode (in the range 0.1-1.0 μm) and two coarse modes (CM1 in the range 1.0-3.0 μm, and CM2 in the range 3.0-10 μm). From 50% to 90% of the PM10 mass comes from particles of a size smaller than 1.0 μm. The two coarse modes represented from ˜5% to ˜35% of the PM10, showing opposite seasonal trends (CM1 decreased while CM2 increased). During summer, PM10 mass concentration increased to a maximum of ˜1.6 μg m-3 at mid-December, while

Steps Toward an EOS-Era Aerosol Air Mass Type Climatology

NASA Technical Reports Server (NTRS)

Kahn, Ralph A.

2012-01-01

We still have a way to go to develop a global climatology of aerosol type from the EOS-era satellite data record that currently spans more than 12 years of observations. We have demonstrated the ability to retrieve aerosol type regionally, providing a classification based on the combined constraints on particle size, shape, and single-scattering albedo (SSA) from the MISR instrument. Under good but not necessarily ideal conditions, the MISR data can distinguish three-to-five size bins, two-to-four bins in SSA, and spherical vs. non-spherical particles. However, retrieval sensitivity varies enormously with scene conditions. So, for example, there is less information about aerosol type when the mid-visible aerosol optical depth (AOD) is less that about 0.15 or 0.2.

Resolving the Aerosol Piece of the Global Climate Picture

NASA Astrophysics Data System (ADS)

Kahn, R. A.

2017-12-01

Factors affecting our ability to calculate climate forcing and estimate model predictive skill include direct radiative effects of aerosols and their indirect effects on clouds. Several decades of Earth-observing satellite observations have produced a global aerosol column-amount (AOD) record, but an aerosol microphysical property record required for climate and many air quality applications is lacking. Surface-based photometers offer qualitative aerosol-type classification, and several space-based instruments map aerosol air-mass types under favorable conditions. However, aerosol hygroscopicity, mass extinction efficiency (MEE), and quantitative light absorption, must be obtained from in situ measurements. Completing the aerosol piece of the climate picture requires three elements: (1) continuing global AOD and qualitative type mapping from space-based, multi-angle imagers and aerosol vertical distribution from near-source stereo imaging and downwind lidar, (2) systematic, quantitative in situ observations of particle properties unobtainable from space, and (3) continuing transport modeling to connect observations to sources, and extrapolate limited sampling in space and time. At present, the biggest challenges to producing the needed aerosol data record are: filling gaps in particle property observations, maintaining global observing capabilities, and putting the pieces together. Obtaining the PDFs of key particle properties, adequately sampled, is now the leading observational deficiency. One simplifying factor is that, for a given aerosol source and season, aerosol amounts often vary, but particle properties tend to be repeatable. SAM-CAAM (Systematic Aircraft Measurements to Characterize Aerosol Air Masses), a modest aircraft payload deployed frequently could fill this gap, adding value to the entire satellite data record, improving aerosol property assumptions in retrieval algorithms, and providing MEEs to translate between remote-sensing optical constraints

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

NASA Astrophysics Data System (ADS)

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

2006-12-01

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

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).

A one-dimensional sectional aerosol model integrated with mesoscale meteorological data to study marine boundary layer aerosol dynamics

NASA Astrophysics Data System (ADS)

Caffrey, Peter F.; Hoppel, William A.; Shi, Jainn J.

2006-12-01

The dynamics of aerosols in the marine boundary layer are simulated with a one-dimensional, multicomponent, sectional aerosol model using vertical profiles of turbulence, relative humidity, temperature, vertical velocity, cloud cover, and precipitation provided by 3-D mesoscale meteorological model output. The Naval Research Laboratory's (NRL) sectional aerosol model MARBLES (Fitzgerald et al., 1998a) was adapted to use hourly meteorological input taken from NRL's Coupled Ocean-Atmosphere Prediction System (COAMPS). COAMPS-generated turbulent mixing coefficients and large-scale vertical velocities determine vertical exchange within the marine boundary layer and exchange with the free troposphere. Air mass back trajectories were used to define the air column history along which the meteorology was retrieved for use with the aerosol model. Details on the integration of these models are described here, as well as a description of improvements made to the aerosol model, including transport by large-scale vertical motions (such as subsidence and lifting), a revised sea-salt aerosol source function, and separate tracking of sulfate mass from each of the five sources (free tropospheric, nucleated, condensed from gas phase oxidation products, cloud-processed, and produced from heterogeneous oxidation of S(IV) on sea-salt aerosol). Results from modeling air masses arriving at Oahu, Hawaii, are presented, and the relative contribution of free-tropospheric sulfate particles versus sea-salt aerosol from the surface to CCN concentrations is discussed. Limitations and benefits of the method are presented, as are sensitivity analyses of the effect of large-scale vertical motions versus turbulent mixing.

Photochemical Assessment Monitoring Stations (PAMS)

EPA Pesticide Factsheets

Photochemical Assessment Monitoring Stations (PAMS). This file provides information on the numbers and distribution (latitude/longitude) of air monitoring sites which measure ozone precursors (approximately 60 volatile hydrocarbons and carbonyl), as required by the 1990 Clean Air Act Amendments, in areas with persistently high ozone levels (mostly large metropolitan areas). In these areas, the States have established ambient air monitoring sites which collect and report detailed data for volatile organic compounds, nitrogen oxides, ozone and meteorological parameters. This file displays 199 monitoring sites reporting measurements for 2010. A wide range of related monitoring site attributes is also provided.

PAM multiplicity marks genomic target sites as inhibitory to CRISPR-Cas9 editing

PubMed Central

Malina, Abba; Cameron, Christopher J. F.; Robert, Francis; Blanchette, Mathieu; Dostie, Josée; Pelletier, Jerry

2015-01-01

In CRISPR-Cas9 genome editing, the underlying principles for selecting guide RNA (gRNA) sequences that would ensure for efficient target site modification remain poorly understood. Here we show that target sites harbouring multiple protospacer adjacent motifs (PAMs) are refractory to Cas9-mediated repair in situ. Thus we refine which substrates should be avoided in gRNA design, implicating PAM density as a novel sequence-specific feature that inhibits in vivo Cas9-driven DNA modification. PMID:26644285

Single particle characterization using a light scattering module coupled to a time-of-flight aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Cross, E. S.; Onasch, T. B.; Canagaratna, M.; Jayne, J. T.; Kimmel, J.; Yu, X.-Y.; Alexander, M. L.; Worsnop, D. R.; Davidovits, P.

2008-12-01

We present the first single particle results obtained using an Aerodyne time-of-flight aerosol mass spectrometer coupled with a light scattering module (LS-ToF-AMS). The instrument was deployed at the T1 ground site approximately 40 km northeast of the Mexico City Metropolitan Area (MCMA) as part of the MILAGRO field study in March of 2006. The instrument was operated as a standard AMS from 12-30 March, acquiring average chemical composition and size distributions for the ambient aerosol, and in single particle mode from 27-30 March. Over a 75-h sampling period, 12 853 single particle mass spectra were optically triggered, saved, and analyzed. The correlated optical and chemical detection allowed detailed examination of single particle collection and quantification within the LS-ToF-AMS. The single particle data enabled the mixing states of the ambient aerosol to be characterized within the context of the size-resolved ensemble chemical information. The particulate mixing states were examined as a function of sampling time and most of the particles were found to be internal mixtures containing many of the organic and inorganic species identified in the ensemble analysis. The single particle mass spectra were deconvolved, using techniques developed for ensemble AMS data analysis, into HOA, OOA, NH4NO3, (NH4)2SO4, and NH4Cl fractions. Average single particle mass and chemistry measurements are shown to be in agreement with ensemble MS and PTOF measurements. While a significant fraction of ambient particles were internal mixtures of varying degrees, single particle measurements of chemical composition allowed the identification of time periods during which the ambient ensemble was externally mixed. In some cases the chemical composition of the particles suggested a likely source. Throughout the full sampling period, the ambient ensemble was an external mixture of combustion-generated HOA particles from local sources (e.g. traffic), with number concentrations peaking

BioAerosol Mass Spectrometry: Reagentless Detection of Individual Airborne Spores and Other Bioagent Particles Based on Laser Desorption/Ionization Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steele, Paul Thomas

2004-09-01

Better devices are needed for the detection of aerosolized biological warfare agents. Advances in the ongoing development of one such device, the BioAerosol Mass Spectrometry (BAMS) system, are described here in detail. The system samples individual, micrometer-sized particles directly from the air and analyzes them in real-time without sample preparation or use of reagents. At the core of the BAMS system is a dual-polarity, single-particle mass spectrometer with a laser based desorption and ionization (DI) system. The mass spectra produced by early proof-of-concept instruments were highly variable and contained limited information to differentiate certain types of similar biological particles. Themore » investigation of this variability and subsequent changes to the DI laser system are described. The modifications have reduced the observed variability and thereby increased the usable information content in the spectra. These improvements would have little value without software to analyze and identify the mass spectra. Important improvements have been made to the algorithms that initially processed and analyzed the data. Single particles can be identified with an impressive level of accuracy, but to obtain significant reductions in the overall false alarm rate of the BAMS instrument, alarm decisions must be made dynamically on the basis of multiple analyzed particles. A statistical model has been developed to make these decisions and the resulting performance of a hypothetical BAMS system is quantitatively predicted. The predictions indicate that a BAMS system, with reasonably attainable characteristics, can operate with a very low false alarm rate (orders of magnitude lower than some currently fielded biodetectors) while still being sensitive to small concentrations of biological particles in a large range of environments. Proof-of-concept instruments, incorporating some of the modifications described here, have already performed well in independent testing.« less

Characterization of biomass burning aerosols produced in the laboratory with a light-scattering aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Middlebrook, A. M.; Adler, G. A.; Coggon, M.; De Gouw, J. A.; Franchin, A.; Gilman, J.; Koss, A.; Krechmer, J. E.; Lamb, K.; Manfred, K.; Roberts, J. M.; Schwarz, J. P.; Sekimoto, K.; Selimovic, V.; Stockwell, C.; Wagner, N.; Warneke, C.; Washenfelder, R. A.; Womack, C.; Yokelson, R. J.; Yuan, B.

2017-12-01

During the 2016 NOAA FIREX project at the Missoula Fire Sciences Laboratory, small fires of known fuel type and properties were ignited to characterize their direct emissions with a large variety of new sampling methods. Two types of experiments were employed: sampling smoke directly from the exhaust stack throughout the lifecycle of the fires (stack burns) or sampling when the exhaust vent was closed to fill the room with smoke (room burns). For both types of burns, photo-oxidation chambers were at times used to mimic aging in the atmosphere. During all these experiments, we measured the non-refractory components of the smoke particles using an Aerodyne compact time-of-flight aerosol mass spectrometer (AMS) with a light scattering module and diluted the sample line as little as possible (usually by a factor of 10) without overwhelming our instrument. For the stack burns, our AMS was placed near the top of the exhaust stack to capture the composition and size distribution during the rapidly changing stages of the fires. We found that the chemical composition of the aerosols varied with fuel type and combustion conditions on time scales of a few minutes as the fuels went through different stages of heating and combustion. For the room burns, we obtained additional measurements with the light-scattering module aimed at understanding how well smoke particles are measured with the AMS, along with characterization of their physical properties. We will present a summary of our results, with connections to their relevance for constraining model treatments of fire emissions on the atmosphere.

Online and offline mass spectrometric study of the impact of oxidation and ageing on glyoxal chemistry and uptake onto ammonium sulfate aerosols.

PubMed

Hamilton, Jacqueline F; Baeza-Romero, M Teresa; Finessi, Emanuela; Rickard, Andrew R; Healy, Robert M; Peppe, Salvatore; Adams, Thomas J; Daniels, Mark J S; Ball, Stephen M; Goodall, Iain C A; Monks, Paul S; Borrás, Esther; Muñoz, Amalia

2013-01-01

Recent laboratory and modelling studies have shown that reactive uptake of low molecular weight alpha-dicarbonyls such as glyoxal (GLY) by aerosols is a potentially significant source of secondary organic aerosol (SOA). However, previous studies disagree in the magnitude of the uptake of GLY, the mechanism involved and the physicochemical factors affecting particle formation. In this study, the chemistry of GLY with ammonium sulfate (AS) in both bulk laboratory solutions and in aerosol particles is investigated. For the first time, Aerosol Time of Flight Mass Spectrometry (ATOFMS), a single particle technique, is used together with offline (ESI-MS and LC-MS2) mass spectrometric techniques to investigate the change in composition of bulk solutions of GLY and AS resulting from aqueous photooxidation by OH and from ageing of the solutions in the dark. The mass spectral ions obtained in these laboratory studies were used as tracers of GLY uptake and chemistry in AS seed particles in a series of experiments carried out under dark and natural irradiated conditions at the outdoor European Photo-reactor (EUPHORE). Glyoxal oligomers formed were not detected by the ATOFMS, perhaps due to inefficient absorption at the laser wavelength. However, the presence of organic nitrogen compounds, formed by reaction of GLY with ammonia was confirmed, resulting in an increase in the absorption efficiency of the aerosol, and this increased the number of particles successfully ionised by the ATOFMS. A number of light absorbing organic nitrogen species, including 1H-imidazole, 1H-imidazole-2-carboxaldehyde, 2,2'-bis-imidazole and a glyoxal substituted 2,2'-bisimidazole, previously identified in aqueous laboratory solutions, were also identified in chamber aerosol and formed on atmospherically relevant timescales. An additional compound, predicted to be 1,2,5-oxadiazole, had an enhanced formation rate when the chamber was open and is predicted to be formed via a light activated pathway

Simultaneous aerosol mass spectrometry and chemical ionisation mass spectrometry measurements during a biomass burning event in the UK: insights into nitrate chemistry

NASA Astrophysics Data System (ADS)

Reyes-Villegas, Ernesto; Priestley, Michael; Ting, Yu-Chieh; Haslett, Sophie; Bannan, Thomas; Le Breton, Michael; Williams, Paul I.; Bacak, Asan; Flynn, Michael J.; Coe, Hugh; Percival, Carl; Allan, James D.

2018-03-01

Over the past decade, there has been an increasing interest in short-term events that negatively affect air quality such as bonfires and fireworks. High aerosol and gas concentrations generated from public bonfires or fireworks were measured in order to understand the night-time chemical processes and their atmospheric implications. Nitrogen chemistry was observed during Bonfire Night with nitrogen containing compounds in both gas and aerosol phases and further N2O5 and ClNO2 concentrations, which depleted early next morning due to photolysis of NO3 radicals and ceasing production. Particulate organic oxides of nitrogen (PONs) concentrations of 2.8 µg m-3 were estimated using the m / z 46 : 30 ratios from aerosol mass spectrometer (AMS) measurements, according to previously published methods. Multilinear engine 2 (ME-2) source apportionment was performed to determine organic aerosol (OA) concentrations from different sources after modifying the fragmentation table and it was possible to identify two PON factors representing primary (pPON_ME2) and secondary (sPON_ME2) contributions. A slight improvement in the agreement between the source apportionment of the AMS and a collocated AE-31 Aethalometer was observed after modifying the prescribed fragmentation in the AMS organic spectrum (the fragmentation table) to determine PON sources, which resulted in an r2 = 0.894 between biomass burning organic aerosol (BBOA) and babs_470wb compared to an r2 = 0.861 obtained without the modification. Correlations between OA sources and measurements made using time-of-flight chemical ionisation mass spectrometry with an iodide adduct ion were performed in order to determine possible gas tracers to be used in future ME-2 analyses to constrain solutions. During Bonfire Night, strong correlations (r2) were observed between BBOA and methacrylic acid (0.92), acrylic acid (0.90), nitrous acid (0.86), propionic acid, (0.85) and hydrogen cyanide (0.76). A series of

A Novel M1 PAM VU0486846 Exerts Efficacy in Cognition Models without Displaying Agonist Activity or Cholinergic Toxicity.

PubMed

Rook, Jerri M; Bertron, Jeanette L; Cho, Hyekyung P; Garcia-Barrantes, Pedro M; Moran, Sean P; Maksymetz, James T; Nance, Kellie D; Dickerson, Jonathan W; Remke, Daniel H; Chang, Sichen; Harp, Joel M; Blobaum, Anna L; Niswender, Colleen M; Jones, Carrie K; Stauffer, Shaun R; Conn, P Jeffrey; Lindsley, Craig W

2018-05-08

Selective activation of the M 1 subtype of muscarinic acetylcholine receptor, via positive allosteric modulation (PAM), is an exciting strategy to improve cognition in schizophrenia and Alzheimer's disease patients. However, highly potent M 1 ago-PAMs, such as MK-7622, PF-06764427, and PF-06827443, can engender excessive activation of M 1 , leading to agonist actions in the prefrontal cortex (PFC) that impair cognitive function, induce behavioral convulsions, and result in other classic cholinergic adverse events (AEs). Here, we report a fundamentally new and highly selective M 1 PAM, VU0486846. VU0486846 possesses only weak agonist activity in M 1 -expressing cell lines with high receptor reserve and is devoid of agonist actions in the PFC, unlike previously reported ago-PAMs MK-7622, PF-06764427, and PF-06827443. Moreover, VU0486846 shows no interaction with antagonist binding at the orthosteric acetylcholine (ACh) site (e.g., neither bitopic nor displaying negative cooperativity with [ 3 H]-NMS binding at the orthosteric site), no seizure liability at high brain exposures, and no cholinergic AEs. However, as opposed to ago-PAMs, VU0486846 produces robust efficacy in the novel object recognition model of cognitive function. Importantly, we show for the first time that an M 1 PAM can reverse the cognitive deficits induced by atypical antipsychotics, such as risperidone. These findings further strengthen the argument that compounds with modest in vitro M 1 PAM activity (EC 50 > 100 nM) and pure-PAM activity in native tissues display robust procognitive efficacy without AEs mediated by excessive activation of M 1 . Overall, the combination of compound assessment with recombinant in vitro assays (mindful of receptor reserve), native tissue systems (PFC), and phenotypic screens (behavioral convulsions) is essential to fully understand and evaluate lead compounds and enhance success in clinical development.

Biological applications of an LCoS-based programmable array microscope (PAM)

NASA Astrophysics Data System (ADS)

Hagen, Guy M.; Caarls, Wouter; Thomas, Martin; Hill, Andrew; Lidke, Keith A.; Rieger, Bernd; Fritsch, Cornelia; van Geest, Bert; Jovin, Thomas M.; Arndt-Jovin, Donna J.

2007-02-01

We report on a new generation, commercial prototype of a programmable array optical sectioning fluorescence microscope (PAM) for rapid, light efficient 3D imaging of living specimens. The stand-alone module, including light source(s) and detector(s), features an innovative optical design and a ferroelectric liquid-crystal-on-silicon (LCoS) spatial light modulator (SLM) instead of the DMD used in the original PAM design. The LCoS PAM (developed in collaboration with Cairn Research, Ltd.) can be attached to a port of a(ny) unmodified fluorescence microscope. The prototype system currently operated at the Max Planck Institute incorporates a 6-position high-intensity LED illuminator, modulated laser and lamp light sources, and an Andor iXon emCCD camera. The module is mounted on an Olympus IX71 inverted microscope with 60-150X objectives with a Prior Scientific x,y, and z high resolution scanning stages. Further enhancements recently include: (i) point- and line-wise spectral resolution and (ii) lifetime imaging (FLIM) in the frequency domain. Multiphoton operation and other nonlinear techniques should be feasible. The capabilities of the PAM are illustrated by several examples demonstrating single molecule as well as lifetime imaging in live cells, and the unique capability to perform photoconversion with arbitrary patterns and high spatial resolution. Using quantum dot coupled ligands we show real-time binding and subsequent trafficking of individual ligand-growth factor receptor complexes on and in live cells with a temporal resolution and sensitivity exceeding those of conventional CLSM systems. The combined use of a blue laser and parallel LED or visible laser sources permits photoactivation and rapid kinetic analysis of cellular processes probed by photoswitchable visible fluorescent proteins such as DRONPA.

Long-Term Observations on Aerosol Elemental Carbon and Mass Concentrations in Winter-Time in New Delhi: Implications for Local Source Changes

NASA Astrophysics Data System (ADS)

Aggarwal, S. G.; Singh, K.; Singh, N.; Gupta, P. K.

2009-12-01

Fossil-fuel and bio-fuel burning are the two major sources identified for high carbonaceous aerosol loadings in several mega cities in India. In the last decade, according to a report from the Central Pollution Control Board (CPCB, 1999), the vehicular emission (mostly diesel-powered engines) was contributed to ~67% of the total air pollution load in New Delhi. Therefore, a policy decision was taken by the government, and most of the diesel-powered engines were converted to compressed natural gas (CNG) -powered engines by 2003. To better understand the effect of these changes on air quality, we collected high volume aerosol samples (total suspended particles, TSP) mostly for a day basis at our institute building in New Delhi almost everyday during winter season (November to January) from 2002 to 2008. We found very high mean aerosol loading, i.e., 488±47 μg m-3 in 2002 winter, which dropped significantly to 280±73 μg m-3 in 2003 winter. Thereafter, a steadily increased trend of aerosol mass loadings was observed, i.e., 339±112, 339±120, 412±107 and 444±55 μg m-3 in 2004, 2005, 2006 and 2007 winters, respectively. Similar trend was also observed for elemental carbon (EC) concentration in TSP, which was peaked in 2002 (47±11 μg m-3) and minimized in 2003 (32±6 μg m-3), and then gradually increased to 41±8 μg m-3 in 2007 winter. These decline trends of aerosol mass and EC concentrations in 2003 can be explained well, because of the conversion of diesel engine to CNG engines of public transport facilities. However, again increase in aerosol mass and EC concentrations possibly because of a high increase in road traffic in recent years. According to the economic survey of New Delhi 2008-09, the number of vehicles (which includes all types of engines, i.e., petrol, diesel and CNG) has grown from ~3.3 millions in 1997-98 to ~5.6 millions in 2007-08. The influence of engine types and vehicle population on aerosol loading can also be explained well by SO2 and

40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass...

40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass...

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

NASA Astrophysics Data System (ADS)

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

2011-12-01

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

Measurements of aerosol chemical composition in boreal forest summer conditions

NASA Astrophysics Data System (ADS)

ńijälä, M.; Junninen, H.; Ehn, M.; Petäjä, T.; Vogel, A.; Hoffmann, T.; Corrigan, A.; Russell, L.; Makkonen, U.; Virkkula, A.; Mäntykenttä, J.; Kulmala, M.; Worsnop, D.

2012-04-01

Boreal forests are an important biome, covering vast areas of the northern hemisphere and affecting the global climate change via various feedbacks [1]. Despite having relatively few anthropogenic primary aerosol sources, they always contain a non-negligible aerosol population [2]. This study describes aerosol chemical composition measurements using Aerodyne Aerosol Mass Spectrometer (C-ToF AMS, [3]), carried out at a boreal forest area in Hyytiälä, Southern Finland. The site, Helsinki University SMEAR II measurement station [4], is situated at a homogeneous Scots pine (Pinus sylvestris) forest stand. In addition to the station's permanent aerosol, gas phase and meteorological instruments, during the HUMPPA (Hyytiälä United Measurements of Photochemistry and Particles in Air) campaign in July 2010, a very comprehensive set of atmospheric chemistry measurement instrumentation was provided by the Max Planck Institute for chemistry, Johannes Gutenberg-University, University of California and the Finnish Meteorological institute. In this study aerosol chemical composition measurements from the campaign are presented. The dominant aerosol chemical species during the campaign were the organics, although periods with elevated amounts of particulate sulfates were also seen. The overall AMS measured particle mass concentrations varied from near zero to 27 μg/m observed during a forest fire smoke episode. The AMS measured aerosol mass loadings were found to agree well with DMPS derived mass concentrations (r2=0.998). The AMS data was also compared with three other aerosol instruments. The Marga instrument [5] was used to provide a quantitative semi-online measurement of inorganic chemical compounds in particle phase. Fourier Transform Infrared Spectroscopy (FTIR) analysis was performed on daily filter samples, enabling the identification and quantification of organic aerosol subspecies. Finally an Atmospheric Pressure Chemical Ionization Ion Trap Mass Spectrometer (APCI

Exploring with PAM: Prospecting ANTS Missions for Solar System Surveys

NASA Astrophysics Data System (ADS)

Clark, P. E.; Rilee, M. L.; Curtis, S. A.

2003-03-01

ANTS (Autonomous Nano Technology Swarm of hundreds of picoclass autonomous spacecraft) have many applications. A version designed for surveying and the resource potential of the asteroid belt, called PAM (Prospecting ANTS Mission), is examined here.

Physicochemical Characterization of Capstone Depleted Uranium Aerosols I: Uranium Concentration in Aerosols as a Function of Time and Particle Size

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parkhurst, MaryAnn; Cheng, Yung-Sung; Kenoyer, Judson L.

2009-03-01

During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing depleted uranium were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols weremore » evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time particularly within the first minute after the shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% 30 min after perforation. In the Bradley vehicle, the initial (and maximum) uranium concentration was lower than those observed in the Abrams tank and decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in the cyclone samplers, which collected aerosol continuously for 2 h post perforation. The percentages of uranium mass in the cyclone separator stages from the Abrams tank tests ranged from 38% to 72% and, in most cases, varied with particle size, typically with less uranium associated with the smaller particle sizes. Results with the Bradley vehicle ranged from 18% to 29% and were not specifically correlated with particle size.« less

Aerosol Composition and Variability in Baltimore Measured during DISCOVER-AQ

NASA Astrophysics Data System (ADS)

Beyersdorf, A. J.; Ziemba, L. D.; Chen, G.; Thornhill, K. L.; Winstead, E. L.; Diskin, G. S.; Chatfield, R. B.; Natraj, V.; Anderson, B. E.

2012-12-01

In order to relate satellite-based measurements of aerosols to ground-level air quality, the correlation between aerosol optical properties (wavelength-dependent scattering and absorption measured by satellites) and mass measurements of aerosol loading (i.e. PM2.5 used for air quality monitoring) must be understood. This connection varies with many factors including those specific to the aerosol type (such as composition, size, hygroscopicity, and mass scattering and absorption efficiencies) and to the surrounding atmosphere (such as temperature, relative humidity and altitude). The DISCOVER-AQ (Deriving Information on Surface conditions from COlumn and VERtically resolved observations relevant to Air Quality) project was designed to provide a unique dataset for determining variability in and correlations between aerosol loading, composition, optical properties and meteorological conditions. Extensive in-situ profiling of the lower atmosphere in the Baltimore-Washington D.C. region was performed during fourteen flights during July 2011. Identical flight plans and profile locations throughout the campaign provide meaningful statistics for analysis. Measured aerosol mass was composed primarily of ammonium sulfate (campaign average of 36%) and water-soluble organics (58%). A distinct difference in composition was related to aerosol loading with high-loading days having a proportionally larger percentage of ammonium sulfate (up to 60%). This composition shift causes a change in the water-uptake potential (hygroscopicity) of the aerosols with higher relative organic composition decreasing water-uptake. On average, sulfate mass increased during the day due to increased photochemistry, while organics decreased. Analysis of the linkage between aerosol loading and optical properties was also performed. The absorption by black carbon was dependent on the amount of organic coating with an increase in mass absorption efficiency from 7.5 m2/g for bare soot to 16 m2/g at an

Time-Resolved Molecular Characterization of Limonene/Ozone Aerosol using High-Resolution Electrospray Ionization Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bateman, Adam P.; Nizkorodov, Serguei; Laskin, Julia

2009-09-09

Molecular composition of limonene/O3 secondary organic aerosol (SOA) was investigated using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) as a function of reaction time. SOA was generated by ozonation of D-limonene in a reaction chamber and sampled at different time intervals using a cascade impactor. The SOA samples were extracted into acetonitrile and analyzed using a HR-ESI-MS instrument with a resolving power of 100,000 (m/Δm). The resulting mass spectra provided detailed information about the extent of oxidation inferred from the O:C ratios, double bond equivalency (DBE) factors, and aromaticity indexes (AI) in hundreds of identified individual SOA species.

Intercomparison and closure calculations using measurements of aerosol species and optical properties during the Yosemite Aerosol Characterization Study

NASA Astrophysics Data System (ADS)

Malm, William C.; Day, Derek E.; Carrico, Christian; Kreidenweis, Sonia M.; Collett, Jeffrey L.; McMeeking, Gavin; Lee, Taehyoung; Carrillo, Jacqueline; Schichtel, Bret

2005-07-01

Physical and optical properties of inorganic aerosols have been extensively studied, but less is known about carbonaceous aerosols, especially as they relate to the non-urban settings such as our nation's national parks and wilderness areas. Therefore an aerosol characterization study was conceived and implemented at one national park that is highly impacted by carbonaceous aerosols, Yosemite. The primary objective of the study was to characterize the physical, chemical, and optical properties of a carbon-dominated aerosol, including the ratio of total organic matter weight to organic carbon, organic mass scattering efficiencies, and the hygroscopic characteristics of a carbon-laden ambient aerosol, while a secondary objective was to evaluate a variety of semi-continuous monitoring systems. Inorganic ions were characterized using 24-hour samples that were collected using the URG and Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring systems, the micro-orifice uniform deposit impactor (MOUDI) cascade impactor, as well as the semi-continuous particle-into-liquid sampler (PILS) technology. Likewise, carbonaceous material was collected over 24-hour periods using IMPROVE technology along with the thermal optical reflectance (TOR) analysis, while semi-continuous total carbon concentrations were measured using the Rupprecht and Patashnick (R&P) instrument. Dry aerosol number size distributions were measured using a differential mobility analyzer (DMA) and optical particle counter, scattering coefficients at near-ambient conditions were measured with nephelometers fitted with PM10 and PM2.5 inlets, and "dry" PM2.5 scattering was measured after passing ambient air through Perma Pure Nafion® dryers. In general, the 24-hour "bulk" measurements of various aerosol species compared more favorably with each other than with the semi-continuous data. Semi-continuous sulfate measurements correlated well with the 24-hour measurements, but were biased low by

Breast imaging using the Twente photoacoustic mammoscope (PAM): new clinical measurements

NASA Astrophysics Data System (ADS)

Heijblom, Michelle; Piras, Daniele; Ten Tije, Ellen; Xia, Wenfeng; van Hespen, Johan; Klaase, Joost; van den Engh, Frank; van Leeuwen, Ton; Steenbergen, Wiendelt; Manohar, Srirang

2011-07-01

Worldwide, yearly about 450,000 women die from the consequences of breast cancer. Current imaging modalities are not optimal in discriminating benign from malignant tissue. Visualizing the malignancy-associated increased hemoglobin concentration might significantly improve early diagnosis of breast cancer. Since photoacoustic imaging can visualize hemoglobin in tissue with optical contrast and ultrasound-like resolution, it is potentially an ideal method for early breast cancer imaging. The Twente Photoacoustic Mammoscope (PAM) has been developed specifically for breast imaging. Recently, a large clinical study has been started in the Medisch Spectrum Twente in Oldenzaal using PAM. In PAM, the breast is slightly compressed between a window for laser light illumination and a flat array ultrasound detector. The measurements are performed using a Q-switched Nd:YAG laser, pulsed at 1064 nm and a 1 MHz unfocused ultrasound detector array. Three-dimensional data are reconstructed using a delay and sum reconstruction algorithm. Those reconstructed images are compared with conventional imaging and histopathology. In the first phase of the study 12 patients with a malignant lesion and 2 patients with a benign cyst have been measured. The results are used to guide developments in photoacoustic mammography in order to pave the way towards an optimal technique for early diagnosis of breast cancer.

Seven years of aerosol scattering hygroscopic growth measurements from SGP: Factors influencing water uptake: Aerosol Scattering Hygroscopic Growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jefferson, A.; Hageman, D.; Morrow, H.

Long-term measurements of changes in the aerosol scattering coefficient hygroscopic growth at the U.S. Department of Energy Southern Great Plains site provide information on the seasonal as well as size and chemical dependence of aerosol hygroscopic growth. Annual average sub 10 um fRH values (the ratio of aerosol scattering at 85%/40% RH) were 1.75 and 1.87 for the gamma and kappa fit algorithms, respectively. The study found higher growth rates in the winter and spring seasons that correlated with high aerosol nitrate mass fraction. FRH, exhibited strong, but differing correlations with the scattering Ångström exponent and backscatter fraction, two opticalmore » size-dependent parameters. The aerosol organic fraction had a strong influence, with fRH decreasing with increases in the organic mass fraction and absorption Ångström exponent and increasing with the aerosol single scatter albedo. Uncertainty analysis if the fit algorithms revealed high uncertainty at low scattering coefficients and slight increases in uncertainty at high RH and fit parameters values.« less

Sedimentological characteristics of the 2015 Tropical Cyclone Pam overwash deposits from Vanuatu, South Pacific

NASA Astrophysics Data System (ADS)

Hong, I.; Pilarczyk, J.; Horton, B.; Fritz, H. M.; Kosciuch, T. J.; Wallace, D. J.; Dike, C.; Rarai, A.; Harrison, M. J.; Jockley, F. R.

2016-12-01

Historical observations and overwash sediments deposited by prehistoric tropical cyclones (TC) enable the assessment of long-term patterns of tropical cyclone variability. Prehistoric TC reconstructions, however, are limited in their ability to quantify the intensity of past events. Modern analogues present an opportunity to characterize overwash sediments deposited by a TC of known intensity. On 13 March 2015, TC Pam made landfall on Vanuatu as a Category 5 storm with 10-minute sustained wind speeds as high as 250 km/h. Less than three months after landfall, we (1) measured the height and inland extent of TC Pam's storm surge; and (2) described the sedimentological characteristics of the TC Pam overwash deposits focusing on two of the hardest hit islands, Efate and Tanna. TC Pam's storm surge inundated Vanuatu with maximum high water marks of 5.6 m above mean sea level (MSL) on the island of Efate and 5.5 m above MSL on the island of Tanna. We measured surge heights of 4.2 m above MSL at our study area Manuro on Efate and 3.3 m above MSL at our study area Port Resolution Bay on Tanna. TC Pam deposited a medium-grained (mean: 1.20 Φ), moderately well-sorted (sorting: 0.55 Φ) mixed-carbonate sand with trace amounts of volcanic sediments and coral fragments at Manuro. The sand extends 130 m inland, abruptly transitioning into pumice that extends 400 m inland into Lake Otas. A sharp contact separates the base of the sand and the underlying organic-rich sand unit. In contrast, TC Pam deposited a medium-grained (mean: 1.81 Φ), moderately well-sorted (sorting: 0.67 Φ) volcanic sand at Port Resolution Bay. The sand extends up to 320 m inland. A sharp contact separates the base of the sand and the underlying rooted sandy soil. We found both a coarsening upward and fining upward sequences in trench M1 at Manuro and upward fining in trenches RB 3 and RB 2 at Port Resolution Bay. We used a combination of measured flow heights obtained at the Port Resolution Bay site and

MATRIX-VBS (v1.0): Implementing an Evolving Organic Aerosol Volatility in an Aerosol Microphysics Model

NASA Technical Reports Server (NTRS)

Gao, Chloe Y.; Tsigaridis, Kostas; Bauer, Susanne E.

2017-01-01

The gas-particle partitioning and chemical aging of semi-volatile organic aerosol are presented in a newly developed box model scheme, where its effect on the growth, composition, and mixing state of particles is examined. The volatility-basis set (VBS) framework is implemented into the aerosol microphysical scheme MATRIX (Multiconfiguration Aerosol TRacker of mIXing state), which resolves mass and number aerosol concentrations and in multiple mixing-state classes. The new scheme, MATRIX-VBS, has the potential to significantly advance the representation of organic aerosols in Earth system models by improving upon the conventional representation as non-volatile particulate organic matter, often also with an assumed fixed size distribution. We present results from idealized cases representing Beijing, Mexico City, a Finnish forest, and a southeastern US forest, and investigate the evolution of mass concentrations and volatility distributions for organic species across the gas and particle phases, as well as assessing their mixing state among aerosol populations. Emitted semi-volatile primary organic aerosols evaporate almost completely in the intermediate-volatility range, while they remain in the particle phase in the low-volatility range. Their volatility distribution at any point in time depends on the applied emission factors, oxidation by OH radicals, and temperature. We also compare against parallel simulations with the original scheme, which represented only the particulate and non-volatile component of the organic aerosol, examining how differently the condensed-phase organic matter is distributed across the mixing states in the model. The results demonstrate the importance of representing organic aerosol as a semi-volatile aerosol, and explicitly calculating the partitioning of organic species between the gas and particulate phases.

The physico-chemical evolution of atmospheric aerosols and the gas-particle partitioning of inorganic aerosol during KORUS-AQ

NASA Astrophysics Data System (ADS)

Lee, T.; Park, T.; Lee, J. B.; Lim, Y. J.; Ahn, J.; Park, J. S.; Soo, C. J.; Desyaterik, Y.; Collett, J. L., Jr.

2017-12-01

Aerosols influence climate change directly by scattering and absorption and indirectly by acting as cloud condensation nuclei and some of the effects of aerosols are reduction in visibility, deterioration of human health, and deposition of pollutants to ecosystems. Urban area is large source of aerosols and aerosol precursors. Aerosol sources are both local and from long-range transport. Long-range transport processed aerosol are often dominant sources of aerosol pollution in Korea. To improve our knowledge of aerosol chemistry, Korea and U.S-Air Quality (KORUS-AQ) of Aircraft-based aerosol measurement took place in and around Seoul, Korea during May and June 2016. KORUS-AQ campaigns were conducted to study the chemical characterization and processes of pollutants in the Seoul Metropolitan area to regional scales of Korean peninsula. Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed on aircraft platforms on-board DC-8 (NASA) aircraft. We characterized aerosol chemical properties and mass concentrations of sulfate, nitrate, ammonium and organics in polluted air plumes and investigate the spatial and vertical distribution of the species. The results of studies show that organics is predominant in Aerosol and a significant fraction of the organics is oxygenated organic aerosol (OOA) at the high altitude. Both Nitrate and sulfate can partition between the gas and particle phases. The ratios for HNO3/(N(V) (=gaseous HNO3 + particulate Nitrate) and SO2/(SO2+Sulfate) were found to exhibit quite different distributions between the particles and gas phase for the locations during KORUS-AQ campaign, representing potential for formation of additional particulate nitrate and sulfate. The results of those studies can provide highly resolved temporal and spatial air pollutant, which are valuable for air quality model input parameters for aerosol behaviour.

Comparison of secondary organic aerosol formed with an aerosol flow reactor and environmental reaction chambers: effect of oxidant concentration, exposure time and seed particles on chemical composition and yield

NASA Astrophysics Data System (ADS)

Lambe, A. T.; Chhabra, P. S.; Onasch, T. B.; Brune, W. H.; Hunter, J. F.; Kroll, J. H.; Cummings, M. J.; Brogan, J. F.; Parmar, Y.; Worsnop, D. R.; Kolb, C. E.; Davidovits, P.

2014-12-01

We performed a systematic intercomparison study of the chemistry and yields of SOA generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0×108 to 2.2×1010 molec cm-3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2×106 to 2×107 molec cm-3 over exposure times of several hours. The OH concentration in the chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. A linear correlation analysis of the mass spectra (m=0.91-0.92, r2=0.93-0.94) and carbon oxidation state (m=1.1, r2=0.58) of SOA produced in the flow reactor and environmental chambers for OH exposures of approximately 1011 molec cm-3 s suggests that the composition of SOA produced in the flow reactor and chambers is the same within experimental accuracy as measured with an aerosol mass spectrometer. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors, rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of sulfate seed particles on isoprene SOA yield measurements was examined in the flow reactor. The studies show that seed particles increase the yield of SOA produced in flow reactors by a factor of 3 to 5 and may also account in part for higher SOA yields obtained in the chambers, where seed particles are routinely used.

Chemical characterization of fine particulate matter in Changzhou, China, and source apportionment with offline aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Ye, Zhaolian; Liu, Jiashu; Gu, Aijun; Feng, Feifei; Liu, Yuhai; Bi, Chenglu; Xu, Jianzhong; Li, Ling; Chen, Hui; Chen, Yanfang; Dai, Liang; Zhou, Quanfa; Ge, Xinlei

2017-02-01

Knowledge of aerosol chemistry in densely populated regions is critical for effective reduction of air pollution, while such studies have not been conducted in Changzhou, an important manufacturing base and populated city in the Yangtze River Delta (YRD), China. This work, for the first time, performed a thorough chemical characterization on the fine particulate matter (PM2.5) samples, collected during July 2015 to April 2016 across four seasons in this city. A suite of analytical techniques was employed to measure the organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSIIs), trace elements, and polycyclic aromatic hydrocarbons (PAHs) in PM2.5; in particular, an Aerodyne soot particle aerosol mass spectrometer (SP-AMS) was deployed to probe the chemical properties of water-soluble organic aerosol (WSOA). The average PM2.5 concentration was found to be 108.3 µg m-3, and all identified species were able to reconstruct ˜ 80 % of the PM2.5 mass. The WSIIs occupied about half of the PM2.5 mass (˜ 52.1 %), with SO42-, NO3-, and NH4+ as the major ions. On average, nitrate concentrations dominated over sulfate (mass ratio of 1.21), indicating that traffic emissions were more important than stationary sources. OC and EC correlated well with each other and the highest OC / EC ratio (5.16) occurred in winter, suggesting complex OC sources likely including both secondary and primary ones. Concentrations of eight trace elements (Mn, Zn, Al, B, Cr, Cu, Fe, Pb) can contribute up to ˜ 5.0 % of PM2.5 during winter. PAH concentrations were also high in winter (140.25 ng m-3), which were predominated by median/high molecular weight PAHs with five and six rings. The organic matter including both water-soluble and water-insoluble species occupied ˜ 21.5 % of the PM2.5 mass. SP-AMS determined that the WSOA had average atomic oxygen-to-carbon (O / C), hydrogen-to-carbon (H / C), nitrogen-to-carbon (N / C), and organic

Biomass burning and biogenic aerosols in northern Australia during the SAFIRED campaign

NASA Astrophysics Data System (ADS)

Milic, Andelija; Mallet, Marc D.; Cravigan, Luke T.; Alroe, Joel; Ristovski, Zoran D.; Selleck, Paul; Lawson, Sarah J.; Ward, Jason; Desservettaz, Maximilien J.; Paton-Walsh, Clare; Williams, Leah R.; Keywood, Melita D.; Miljevic, Branka

2017-03-01

There is a lack of knowledge of how biomass burning aerosols in the tropics age, including those in the fire-prone Northern Territory in Australia. This paper reports chemical characterization of fresh and aged aerosols monitored during the 1-month-long SAFIRED (Savannah Fires in the Early Dry Season) field study, with an emphasis on the chemical signature and aging of organic aerosols. The campaign took place in June 2014 during the early dry season when the surface measurement site, the Australian Tropical Atmospheric Research Station (ATARS), located in the Northern Territory, was heavily influenced by thousands of wild and prescribed bushfires. ATARS was equipped with a wide suite of instrumentation for gaseous and aerosol characterization. A compact time-of-flight aerosol mass spectrometer was deployed to monitor aerosol chemical composition. Approximately 90 % of submicron non-refractory mass was composed of organic material. Ozone enhancement in biomass burning plumes indicated increased air mass photochemistry. The diversity in biomass burning emissions was illustrated through variability in chemical signature (e.g. wide range in f44, from 0.06 to 0.18) for five intense fire events. The background particulate loading was characterized using positive matrix factorization (PMF). A PMF-resolved BBOA (biomass burning organic aerosol) factor comprised 24 % of the submicron non-refractory organic aerosol mass, confirming the significance of fire sources. A dominant PMF factor, OOA (oxygenated organic aerosol), made up 47 % of the sampled aerosol, illustrating the importance of aerosol aging in the Northern Territory. Biogenic isoprene-derived organic aerosol factor was the third significant fraction of the background aerosol (28 %).

Flow-Tube Investigations of Hypergolic Reactions of a Dicyanamide Ionic Liquid Via Tunable Vacuum Ultraviolet Aerosol Mass Spectrometry.

PubMed

Chambreau, Steven D; Koh, Christine J; Popolan-Vaida, Denisia M; Gallegos, Christopher J; Hooper, Justin B; Bedrov, Dmitry; Vaghjiani, Ghanshyam L; Leone, Stephen R

2016-10-07

The unusually high heats of vaporization of room-temperature ionic liquids (RTILs) complicate the utilization of thermal evaporation to study ionic liquid reactivity. Although effusion of RTILs into a reaction flow-tube or mass spectrometer is possible, competition between vaporization and thermal decomposition of the RTIL can greatly increase the complexity of the observed reaction products. In order to investigate the reaction kinetics of a hypergolic RTIL, 1-butyl-3-methylimidazolium dicyanamide (BMIM + DCA - ) was aerosolized and reacted with gaseous nitric acid, and the products were monitored via tunable vacuum ultraviolet photoionization time-of-flight mass spectrometry at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source. Reaction product formation at m/z 42, 43, 44, 67, 85, 126, and higher masses was observed as a function of HNO 3 exposure. The identities of the product species were assigned to the masses on the basis of their ionization energies. The observed exposure profile of the m/z 67 signal suggests that the excess gaseous HNO 3 initiates rapid reactions near the surface of the RTIL aerosol. Nonreactive molecular dynamics simulations support this observation, suggesting that diffusion within the particle may be a limiting step. The mechanism is consistent with previous reports that nitric acid forms protonated dicyanamide species in the first step of the reaction.

The pam1 gene is required for meiotic bouquet formation and efficient homologous synapsis in maize (Zea mays L.).

PubMed Central

Golubovskaya, Inna N; Harper, Lisa C; Pawlowski, Wojciech P; Schichnes, Denise; Cande, W Zacheus

2002-01-01

The clustering of telomeres on the nuclear envelope (NE) during meiotic prophase to form the bouquet arrangement of chromosomes may facilitate homologous chromosome synapsis. The pam1 (plural abnormalities of meiosis 1) gene is the first maize gene that appears to be required for telomere clustering, and homologous synapsis is impaired in pam1. Telomere clustering on the NE is arrested or delayed at an intermediate stage in pam1. Telomeres associate with the NE during the leptotene-zygotene transition but cluster slowly if at all as meiosis proceeds. Intermediate stages in telomere clustering including miniclusters are observed in pam1 but not in wild-type meiocytes. The tight bouquet normally seen at zygotene is a rare event. In contrast, the polarization of centromeres vs. telomeres in the nucleus at the leptotene-zygotene transition is the same in mutant and wild-type cells. Defects in homologous chromosome synapsis include incomplete synapsis, nonhomologous synapsis, and unresolved interlocks. However, the number of RAD51 foci on chromosomes in pam1 is similar to that of wild type. We suggest that the defects in homologous synapsis and the retardation of prophase I arise from the irregularity of telomere clustering and propose that pam1 is involved in the control of bouquet formation and downstream meiotic prophase I events. PMID:12524364

Aerosol growth in Titan’s ionosphere

PubMed Central

Lavvas, Panayotis; Yelle, Roger V.; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J.; Wahlund, Jan-Erik; Crary, Frank J.; Snowden, Darci

2013-01-01

Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan’s upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere. PMID:23382231

High-Throughput Characterization of Cascade type I-E CRISPR Guide Efficacy Reveals Unexpected PAM Diversity and Target Sequence Preferences.

PubMed

Fu, Becky Xu Hua; Wainberg, Michael; Kundaje, Anshul; Fire, Andrew Z

2017-08-01

Interactions between Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) RNAs and CRISPR-associated (Cas) proteins form an RNA-guided adaptive immune system in prokaryotes. The adaptive immune system utilizes segments of the genetic material of invasive foreign elements in the CRISPR locus. The loci are transcribed and processed to produce small CRISPR RNAs (crRNAs), with degradation of invading genetic material directed by a combination of complementarity between RNA and DNA and in some cases recognition of adjacent motifs called PAMs (Protospacer Adjacent Motifs). Here we describe a general, high-throughput procedure to test the efficacy of thousands of targets, applying this to the Escherichia coli type I-E Cascade (CRISPR-associated complex for antiviral defense) system. These studies were followed with reciprocal experiments in which the consequence of CRISPR activity was survival in the presence of a lytic phage. From the combined analysis of the Cascade system, we found that (i) type I-E Cascade PAM recognition is more expansive than previously reported, with at least 22 distinct PAMs, with many of the noncanonical PAMs having CRISPR-interference abilities similar to the canonical PAMs; (ii) PAM positioning appears precise, with no evidence for tolerance to PAM slippage in interference; and (iii) while increased guanine-cytosine (GC) content in the spacer is associated with higher CRISPR-interference efficiency, high GC content (>62.5%) decreases CRISPR-interference efficiency. Our findings provide a comprehensive functional profile of Cascade type I-E interference requirements and a method to assay spacer efficacy that can be applied to other CRISPR-Cas systems. Copyright © 2017 by the Genetics Society of America.

Aerosols in Northern Morocco: Input pathways and their chemical fingerprint

NASA Astrophysics Data System (ADS)

Benchrif, A.; Guinot, B.; Bounakhla, M.; Cachier, H.; Damnati, B.; Baghdad, B.

2018-02-01

The Mediterranean basin is one of the most sensitive regions in the world regarding climate change and air quality. Deserts and marine aerosols combine with combustion aerosols from maritime traffic, large urban centers, and at a larger scale from populated industrialized regions in Europe. From Tetouan city located in the North of Morocco, we attempted to better figure out the main aerosol transport pathways and their respective aerosol load and chemical profile by examining air mass back trajectory patterns and aerosol chemical compositions from May 2011 to April 2012. The back trajectory analysis throughout the sampling period led to four clusters, for which meteorological conditions and aerosol chemical characteristics have been investigated. The most frequent cluster (CL3: 39%) corresponds to polluted air masses coming from the Mediterranean Basin, characterized by urban and marine vessels emissions out of Spain and of Northern Africa. Two other polluted clusters were characterized. One is of local origin (CL1: 22%), with a marked contribution from urban aerosols (Rabat, Casablanca) and from biomass burning aerosols. The second (CL2: 32%) defines air masses from the near Atlantic Ocean, affected by pollutants emitted from the Iberian coast. A fourth cluster (CL4: 7%) is characterized by rather clean, fast and rainy oceanic air masses, influenced during their last 24 h before reaching Tetouan by similar sources with those affecting CL2, but to a lesser extent. The chemical data show that carbonaceous species are found in the fine aerosols fraction and are generally from local primary sources (low OC/EC) rather than long-range transported. In addition to fresh traffic and maritime vessel aerosols, our results suggest the contribution of local biomass burning.

Mass or total surface area with aerosol size distribution as exposure metrics for inflammatory, cytotoxic and oxidative lung responses in rats exposed to titanium dioxide nanoparticles.

PubMed

Noël, A; Truchon, G; Cloutier, Y; Charbonneau, M; Maghni, K; Tardif, R

2017-04-01

There is currently no consensus on the best exposure metric(s) for expressing nanoparticle (NP) dose. Although surface area has been extensively studied for inflammatory responses, it has not been as thoroughly validated for cytotoxicity or oxidative stress effects. Since inhaled NPs deposit and interact with lung cells based on agglomerate size, we hypothesize that mass concentration combined with aerosol size distribution is suitable for NP risk assessment. The objective of this study was to evaluate different exposure metrics for inhaled 5 nm titanium dioxide aerosols composed of small (SA < 100 nm) or large (LA > 100 nm) agglomerates at 2, 7, and 20 mg/m 3 on rat lung inflammatory, cytotoxicity, and oxidative stress responses. We found a significant positive correlation ( r = 0.98, p < 0.01) with the inflammatory reaction, measured by the number of neutrophils and the mass concentration when considering all six (SA + LA) aerosols. This correlation was similar ( r = 0.87) for total surface area. Regarding cytotoxicity and oxidative stress responses, measured by lactate dehydrogenase and 8-isoprostane, respectively, and mass or total surface area as an exposure metric, we observed significant positive correlations only with SA aerosols for both the mass concentration and size distribution ( r > 0.91, p < 0.01), as well as for the total surface area ( r > 0.97, p < 0.01). These data show that mass or total surface area concentrations alone are insufficient to adequately predict oxidant and cytotoxic pulmonary effects. Overall, our study indicates that considering NP size distribution along with mass or total surface area concentrations contributes to a more mechanistic discrimination of pulmonary responses to NP exposure.

Determination of the organic aerosol mass to organic carbon ratio in IMPROVE samples.

PubMed

El-Zanan, Hazem S; Lowenthal, Douglas H; Zielinska, Barbara; Chow, Judith C; Kumar, Naresh

2005-07-01

The ratio of organic mass (OM) to organic carbon (OC) in PM(2.5) aerosols at US national parks in the IMPROVE network was estimated experimentally from solvent extraction of sample filters and from the difference between PM(2.5) mass and chemical constituents other than OC (mass balance) in IMPROVE samples from 1988 to 2003. Archived IMPROVE filters from five IMPROVE sites were extracted with dichloromethane (DCM), acetone and water. The extract residues were weighed to determine OM and analyzed for OC by thermal optical reflectance (TOR). On average, successive extracts of DCM, acetone, and water contained 64%, 21%, and 15%, respectively, of the extractable OC, respectively. On average, the non-blank-corrected recovery of the OC initially measured in these samples by TOR was 115+/-42%. OM/OC ratios from the combined DCM and acetone extracts averaged 1.92 and ranged from 1.58 at Indian Gardens, AZ in the Grand Canyon to 2.58 at Mount Rainier, WA. The average OM/OC ratio determined by mass balance was 2.07 across the IMPROVE network. The sensitivity of this ratio to assumptions concerning sulfate neutralization, water uptake by hygroscopic species, soil mass, and nitrate volatilization were evaluated. These results suggest that the value of 1.4 for the OM/OC ratio commonly used for mass and light extinction reconstruction in IMPROVE is too low.

Overview of the aerosol measurements in the UTLS during the POSIDON campaign

NASA Astrophysics Data System (ADS)

Gao, R. S.; Liu, S.; Thornberry, T. D.; Rollins, A. W.; Yu, P.; Woods, S.; Bui, T. V.

2017-12-01

The tropical tropopause layer (TTL) is the main gateway for transport of aerosols from the troposphere to the stratosphere. Studies of aerosol properties in the TTL, however, are very limited. During the NASA Pacific Oxidants, Sulfur, Ice, Dehydration, and cONvection (POSIDON) Experiment in Guam in October 2016, we measured aerosol size distributions onboard the NASA WB-57F high altitude research aircraft up to 19 km. Multiple aerosol vertical profiles showed a robust enhancement of aerosols as a function of altitude between 15 and 19 km, with the aerosol number and mass concentrations of 10 cm-3 and 0.1 µg m-3, respectively, for particles in the size range of 140-3000 nm at 17 km altitude. Simulation using a global sectional aerosol model coupled with the Community Earth System Model generally agreed with aerosol observations, suggesting that the aerosol enhancement was likely due to in-situ particle formation and growth. Concurrent SO2 measurement showed that conversion of SO2 to sulfuric acid alone cannot explain the enhanced aerosol layer at TTL, indicating that other precursors or formation pathways exist for efficient aerosol formation. Using the measured mass concentration and an average vertical air velocity, the aerosol mass flux at the tropopause has been estimated. In addition, we investigated the potential aerosol removal processes and found no evidence for aerosol scavenging by ice.

Submicron particles influenced by mixed biogenic and anthropogenic emissions: high-resolution aerosol mass spectrometry results from the Carbonaceous Aerosols and Radiative Effects Study (CARES)

NASA Astrophysics Data System (ADS)

Setyan, A.; Zhang, Q.; Merkel, M.; Knighton, W. B.; Sun, Y.; Song, C.; Shilling, J. E.; Onasch, T. B.; Herndon, S. C.; Worsnop, D. R.; Fast, J. D.; Zaveri, R. A.; Berg, L. K.; Wiedensohler, A.; Flowers, B. A.; Dubey, M. K.; Subramanian, R.

2012-02-01

The Carbonaceous Aerosols and Radiative Effects Study (CARES) took place in the Sacramento Valley of California in summer 2010. We present results obtained at Cool, CA, the T1 site of the project (~40 km downwind of urban emissions from Sacramento), where we deployed an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) in parallel with complementary instrumentation to characterize the sources and processes of submicron particles (PM1). Cool is located at the foothill of the Sierra Nevada Mountains, where intense biogenic emissions are periodically mixed with urban outflow transported by daytime southwesterly winds from the Sacramento metropolitan area. The particle mass loading was low (3.0 μg m-3 on average) and dominated by organics (80 % of the PM1 mass) followed by sulfate (9.9 %). Organics and sulfate appeared to be externally mixed, as suggested by their different time series (r2 = 0.13) and size distributions. Sulfate showed a bimodal distribution with a droplet mode peaking at ˜400 nm in vacuum aerodynamic diameter (Dva), and a condensation mode at ~150 nm, while organics generally displayed a broad distribution in 60-600 nm (Dva). New particle formation and growth events were observed almost every day, emphasizing the roles of organics and sulfate in new particle growth, especially that of organics. The organic aerosol (OA) had a~nominal formula of C1H1.38N0.004O0.44, thus an average organic mass-to-carbon (OM/OC) ratio of 1.70. Two different oxygenated OA (OOA, 90 % of total OA mass) and a hydrocarbon-like OA (HOA, 10 %) were identified by Positive matrix factorization (PMF) of the high-resolution mass spectra. The more oxidized MO-OOA (O/C = 0.54) corresponded to secondary OA (SOA) primarily influenced by biogenic emissions, while the less oxidized LO-OOA (O/C = 0.42) corresponded to SOA associated with urban transport. The HOA factor corresponded to primary emissions mainly due to local traffic. Twenty three periods of

Estimating Marine Aerosol Particle Volume and Number from Maritime Aerosol Network Data

NASA Technical Reports Server (NTRS)

Sayer, A. M.; Smirnov, A.; Hsu, N. C.; Munchak, L. A.; Holben, B. N.

2012-01-01

As well as spectral aerosol optical depth (AOD), aerosol composition and concentration (number, volume, or mass) are of interest for a variety of applications. However, remote sensing of these quantities is more difficult than for AOD, as it is more sensitive to assumptions relating to aerosol composition. This study uses spectral AOD measured on Maritime Aerosol Network (MAN) cruises, with the additional constraint of a microphysical model for unpolluted maritime aerosol based on analysis of Aerosol Robotic Network (AERONET) inversions, to estimate these quantities over open ocean. When the MAN data are subset to those likely to be comprised of maritime aerosol, number and volume concentrations obtained are physically reasonable. Attempts to estimate surface concentration from columnar abundance, however, are shown to be limited by uncertainties in vertical distribution. Columnar AOD at 550 nm and aerosol number for unpolluted maritime cases are also compared with Moderate Resolution Imaging Spectroradiometer (MODIS) data, for both the present Collection 5.1 and forthcoming Collection 6. MODIS provides a best-fitting retrieval solution, as well as the average for several different solutions, with different aerosol microphysical models. The average solution MODIS dataset agrees more closely with MAN than the best solution dataset. Terra tends to retrieve lower aerosol number than MAN, and Aqua higher, linked with differences in the aerosol models commonly chosen. Collection 6 AOD is likely to agree more closely with MAN over open ocean than Collection 5.1. In situations where spectral AOD is measured accurately, and aerosol microphysical properties are reasonably well-constrained, estimates of aerosol number and volume using MAN or similar data would provide for a greater variety of potential comparisons with aerosol properties derived from satellite or chemistry transport model data.

AEROSOL SAMPLING AND ANALYSIS, PHOENIX, ARIZONA

EPA Science Inventory

An atmospheric sampling program was carried out in the greater Phoenix, Arizona metropolitan area in November, 1975. Objectives of the study were to measure aerosol mass flux through Phoenix and to characterize the aerosol according to particle type and size. The ultimate goal of...

Receptor modeling of near-roadway aerosol mass spectrometer data in Las Vegas, Nevada, with EPA PMF

NASA Astrophysics Data System (ADS)

Brown, S. G.; Lee, T.; Norris, G. A.; Roberts, P. T.; Collett, J. L., Jr.; Paatero, P.; Worsnop, D. R.

2012-01-01

Ambient non-refractory PM1 aerosol particles were measured with an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS) at an elementary school 18 m from the US 95 freeway soundwall in Las Vegas, Nevada, during January 2008. Additional collocated continuous measurements of black carbon (BC), carbon monoxide (CO), nitrogen oxides (NOx), and meteorological data were collected. The US~Environmental Protection Agency's~(EPA) positive matrix factorization (PMF) data analysis tool was used to apportion organic matter (OM) as measured by HR-AMS, and rotational tools in EPA PMF were used to better characterize the solution space and pull resolved factors toward known source profiles. Three- to six-factor solutions were resolved. The four-factor solution was the most interpretable, with the typical AMS PMF factors of hydrocarbon-like organic aerosol (HOA), low-volatility oxygenated organic aerosol (LV-OOA), biomass burning organic aerosol (BBOA), and semi-volatile oxygenated organic aerosol (SV-OOA). When the measurement site was downwind of the freeway, HOA composed about half the OM, with SV-OOA and LV-OOA accounting for the rest. Attempts to pull the PMF factor profiles toward source profiles were successful but did not qualitatively change the results, indicating that these factors are very stable. Oblique edges were present in G-space plots, suggesting that the obtained rotation may not be the most plausible one. Since solutions found by pulling the profiles or using Fpeak retained these oblique edges, there appears to be little rotational freedom in the base solution. On average, HOA made up 26% of the OM, while LV-OOA was highest in the afternoon and accounted for 26% of the OM. BBOA occurred in the evening hours, was predominantly from the residential area to the north, and on average constituted 12% of the OM; SV-OOA accounted for the remaining third of the OM. Use of the pulling techniques available in EPA PMF and ME-2 suggested that the four

Measuring patient activation in Italy: Translation, adaptation and validation of the Italian version of the patient activation measure 13 (PAM13-I).

PubMed

Graffigna, Guendalina; Barello, Serena; Bonanomi, Andrea; Lozza, Edoardo; Hibbard, Judith

2015-12-23

The Patient Activation Measure (PAM13) is an instrument that assesses patient knowledge, skills, and confidence for disease self-management. This cross-sectional study was aimed to validate a culturally-adapted Italian Patient Activation Measure (PAM13-I) for patients with chronic conditions. 519 chronic patients were involved in the Italian validation study and responded to PAM13-I. The PAM 13 was translated into Italian by a standardized forward-backward translation. Data quality was assessed by mean, median, item response, missing values, floor and ceiling effects, internal consistency (Cronbach's alpha and average inter-item correlation), item-rest correlations. Rasch Model and differential item functioning assessed scale properties. Mean PAM13-I score was 66.2. Rasch analysis showed that the PAM13-I is a good measure of patient activation. The level of internal consistency was good (α = 0.88). For all items, the distribution of answers was left-skewed, with a small floor effect (range 1.7-4.5 %) and a moderate ceiling effect (range 27.6-55.0 %). The Italian version formed a unidimensional, probabilistic Guttman-like scale explaining 41 % of the variance. The PAM13-I has been demonstrated to be a valid and reliable measure of patient activation and the present study suggests its applicability to the Italian-speaking chronic patient population. The measure has good psychometric properties and appears to be consistent with the developmental nature of the patient activation phenomenon, although it presents a different ranking order of the items comparing to the American version. PAM13-I can be a useful assessment tool to evaluate interventions aimed at improving patient engagement in healthcare and to train doctors in attuning their communication to the level of patients' activation. Future research could be conducted to further confirm the validity of the PAM13-I.

Pressure application measurement (PAM): a novel behavioural technique for measuring hypersensitivity in a rat model of joint pain.

PubMed

Barton, Nicola J; Strickland, Iain T; Bond, Susan M; Brash, Harry M; Bate, Simon T; Wilson, Alex W; Chessell, Iain P; Reeve, Alison J; McQueen, Daniel S

2007-06-15

Chronic joint pain affects physical well being and can lead to severe psychological and social problems, therefore successful long-term management is highly sought-after. No current behavioural measures of pain used in pre-clinical models mimic the clinical dolorimeter, which provides an objective measure of joint hypersensitivity. In this study we aim to use a novel behavioural readout alongside an established measure to mimic the multifactorial measurements taken in the clinic. Using the pressure application measurement (PAM) device a gradually increasing squeeze was applied across the knee joint of rats until the animal gave an indication of pain or discomfort. PAM and the incapacitance tester were used to detect joint hypersensitivity in a well-established rodent model of adjuvant-induced arthritis. Subsequently, the analgesic effects of prednisolone (1, 3 or 10 mg kg(-1)), morphine (3 mg kg(-1)) and celecoxib (15 mg kg(-1)) were assessed. Both PAM and the incapacitance tester detected a reversal of hypersensitivity 1h post-drug administration. Furthermore, the two readouts were highly correlated, and power analysis indicated that PAM was highly reproducible. In conclusion, PAM provides a novel, accurate behavioural tool for detecting a primary mechanical hypersensitivity in a rat model of chronic inflammatory joint pain.

40 CFR 52.480 - Photochemical Assessment Monitoring Stations (PAMS) Program.

Code of Federal Regulations, 2010 CFR

2010-07-01

... of Columbia's Department of Consumer and Regulatory Affairs submitted a plan for the establishment... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Photochemical Assessment Monitoring Stations (PAMS) Program. 52.480 Section 52.480 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...

40 CFR 52.430 - Photochemical Assessment Monitoring Stations (PAMS) Program.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Photochemical Assessment Monitoring Stations (PAMS) Program. 52.430 Section 52.430 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Natural Resources & Environmental Control submitted a plan for the establishment and implementation of a...

Online molecular characterisation of organic aerosols in an atmospheric chamber using extractive electrospray ionisation mass spectrometry

NASA Astrophysics Data System (ADS)

Gallimore, Peter J.; Giorio, Chiara; Mahon, Brendan M.; Kalberer, Markus

2017-12-01

The oxidation of biogenic volatile organic compounds (VOCs) represents a substantial source of secondary organic aerosol (SOA) in the atmosphere. In this study, we present online measurements of the molecular constituents formed in the gas and aerosol phases during α-pinene oxidation in the Cambridge Atmospheric Simulation Chamber (CASC). We focus on characterising the performance of extractive electrospray ionisation (EESI) mass spectrometry (MS) for particle analysis. A number of new aspects of EESI-MS performance are considered here. We show that relative quantification of organic analytes can be achieved in mixed organic-inorganic particles. A comprehensive assignment of mass spectra for α-pinene derived SOA in both positive and negative ion modes is obtained using an ultra-high-resolution mass spectrometer. We compare these online spectra to conventional offline ESI-MS spectra and find good agreement in terms of the compounds identified, without the need for complex sample work-up procedures. Under our experimental conditions, EESI-MS signals arise only from particle-phase analytes. High-time-resolution (7 min) EESI-MS spectra are compared with simulations from the near-explicit Master Chemical Mechanism (MCM) for a range of reaction conditions. We show that MS peak abundances scale with modelled concentrations for condensable products (pinonic acid, pinic acid, OH-pinonic acid). Relative quantification is achieved throughout SOA formation as the composition, size and mass (5-2400 µg m-3) of particles is evolving. This work provides a robust demonstration of the advantages of EESI-MS for chamber studies over offline ESI-MS (time resolution, relative quantification) and over hard online techniques (molecular information).

Quantitative characterization of colloidal assembly of graphene oxide-silver nanoparticle hybrids using aerosol differential mobility-coupled mass analyses.

PubMed

Nguyen, Thai Phuong; Chang, Wei-Chang; Lai, Yen-Chih; Hsiao, Ta-Chih; Tsai, De-Hao

2017-10-01

In this work, we develop an aerosol-based, time-resolved ion mobility-coupled mass characterization method to investigate colloidal assembly of graphene oxide (GO)-silver nanoparticle (AgNP) hybrid nanostructure on a quantitative basis. Transmission electron microscopy (TEM) and zeta potential (ZP) analysis were used to provide visual information and elemental-based particle size distributions, respectively. Results clearly show a successful controlled assembly of GO-AgNP by electrostatic-directed heterogeneous aggregation between GO and bovine serum albumin (BSA)-functionalized AgNP under an acidic environment. Additionally, physical size, mass, and conformation (i.e., number of AgNP per nanohybrid) of GO-AgNP were shown to be proportional to the number concentration ratio of AgNP to GO (R) and the selected electrical mobility diameter. An analysis of colloidal stability of GO-AgNP indicates that the stability increased with its absolute ZP, which was dependent on R and environmental pH. The work presented here provides a proof of concept for systematically synthesizing hybrid colloidal nanomaterials through the tuning of surface chemistry in aqueous phase with the ability in quantitative characterization. Graphical Abstract Colloidal assembly of graphene oxide-silver nanoparticle hybrids characterized by aerosol differential mobility-coupled mass analyses.

Aerosol Chemical Speciation Monitor (ACSM) Instrument Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, Thomas B.

The Aerodyne Aerosol Chemical Speciation Monitor (ACSM) measures particle mass loading and chemical composition in real time for non-refractory sub-micron aerosol particles. The ACSM is designed for long-term unattended deployment and routine monitoring applications.

Biological particle analysis by mass spectrometry

NASA Technical Reports Server (NTRS)

Vilker, V. L.; Platz, R. M.

1983-01-01

An instrument that analyzes the chemical composition of biological particles in aerosol or hydrosol form was developed. Efforts were directed toward the acquisition of mass spectra from aerosols of biomolecules and bacteria. The filament ion source was installed on the particle analysis by mass spectrometry system. Modifications of the vacuum system improved the sensitivity of the mass spectrometer. After the modifications were incorporated, detailed mass spectra of simple compounds from the three major classes of biomolecules, proteins, nucleic acids, and carbohydrates were obtained. A method of generating bacterial aerosols was developed. The aerosols generated were collected and examined in the scanning electron microscope to insure that the bacteria delivered to the mass spectrometer were intact and free from debris.

Outdoor and indoor aerosol size, number, mass and compositional dynamics at an urban background site during warm season

NASA Astrophysics Data System (ADS)

Talbot, N.; Kubelova, L.; Makes, O.; Cusack, M.; Ondracek, J.; Vodička, P.; Schwarz, J.; Zdimal, V.

2016-04-01

This paper describes the use of a unique valve switching system that allowed for high temporal resolution indoor and outdoor data to be collected concurrently from online C-ToF-AMS, SMPS and OC/EC, and offline BLPI measurements. The results reveal near real-time dynamic aerosol behaviour along a migration path from an outdoor to indoor environment. An outdoor reduction in NR-PM1 mass concentration occurred daily from AM (06:00-12:00) to PM (12:00-18:00). SO4 (26%-37%) [AM/PM] increased proportionally during afternoons at the expense of NO3 (18%-7%). The influences of mixing height, temperature and solar radiation were considered against the mean mass concentration loss for each species. Losses were then calculated according to species via a basic input/output model. NO3 lost the most mass during afternoon periods, which we attribute to the accelerated dissociation of NH4NO3 through increasing temperature and decreasing relative humidity. Indoor/outdoor (I/O) ratios varied from 0.46 for <40 nm to 0.65 for >100 nm. These ratios were calculated using average SMPS PNC measurements over the full campaign and corroborated using a novel technique of calculating I/O penetration ratios through the indoor migration of particles during a new particle formation event. This ratio was then used to observe changes in indoor composition relative to those outdoors. Indoor sampling was carried out in an undisturbed room with no known sources. Indoor concentrations were found to be proportional to those outdoors, with organic matter [2.7 μg/m3] and SO4 [1.7 μg/m3] being the most prominent species. These results are indicative of fairly rapid aerosol penetration, a source-free indoor environment and small afternoon I/O temperature gradients. Fine fraction NO3 was observed indoors in both real-time AMS PM1 and off-line BLPI measurements. Greater mass concentration losses were observed from filter measurements, highlighting an important time dependency factor when investigating semi

Simulating Aerosol Optical Properties With the Aerosol Simulation Program (ASP): Closure Studies Using ARCTAS Data

NASA Astrophysics Data System (ADS)

Alvarado, M. J.; Macintyre, H. L.; Bian, H.; Chin, M.; Wang, C.

2012-12-01

The scattering and absorption of ultraviolet and visible radiation by aerosols can significantly alter actinic fluxes and photolysis rates. Accurate modeling of aerosol optical properties is thus essential to simulating atmospheric chemistry, air quality, and climate. Here we evaluate the aerosol optical property predictions of the Aerosol Simulation Program (ASP) with in situ data on aerosol scattering and absorption gathered during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The model simulations are initialized with in situ data on the aerosol size distribution and composition. We perform a set of sensitivity studies (e.g., internal vs. external mixture, core-in-shell versus Maxwell-Garnett, fraction of the organic carbon mass that is light-absorbing "brown carbon," etc.) to determine the model framework and parameters most consistent with the observations. We compare the ASP results to the aerosol optical property lookup tables in FAST-JX and suggest improvements that will better enable FAST-JX to simulate the impact of aerosols on photolysis rates and atmospheric chemistry.

A technique for rapid source apportionment applied to ambient organic aerosol measurements from a thermal desorption aerosol gas chromatograph (TAG)

DOE PAGES

Zhang, Yaping; Williams, Brent J.; Goldstein, Allen H.; ...

2016-11-25

Here, we present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography–mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG) system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes) (Zhang et al., 2014). Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arrangedmore » into an input data matrix for positive matrix factorization (PMF), where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins) are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. A six-factor PMF comparison among aerosol mass spectrometry (AMS), TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level

A technique for rapid source apportionment applied to ambient organic aerosol measurements from a thermal desorption aerosol gas chromatograph (TAG)

NASA Astrophysics Data System (ADS)

Zhang, Yaping; Williams, Brent J.; Goldstein, Allen H.; Docherty, Kenneth S.; Jimenez, Jose L.

2016-11-01

We present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography-mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG) system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes) (Zhang et al., 2014). Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arranged into an input data matrix for positive matrix factorization (PMF), where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins) are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. A six-factor PMF comparison among aerosol mass spectrometry (AMS), TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level resolution on

Measuring patient activation in The Netherlands: translation and validation of the American short form Patient Activation Measure (PAM13).

PubMed

Rademakers, Jany; Nijman, Jessica; van der Hoek, Lucas; Heijmans, Monique; Rijken, Mieke

2012-07-31

The American short form Patient Activation Measure (PAM) is a 13-item instrument which assesses patient (or consumer) self-reported knowledge, skills and confidence for self-management of one's health or chronic condition. In this study the PAM was translated into a Dutch version; psychometric properties of the Dutch version were established and the instrument was validated in a panel of chronically ill patients. The translation was done according to WHO guidelines. The PAM 13-Dutch was sent to 4178 members of the Dutch National Panel of people with Chronic illness or Disability (NPCD) in April 2010 (study A) and again to a sub sample of this group (N = 973) in June 2010 (study B). Internal consistency, test-retest reliability and cross-validation with the SBSQ-D (a measure for Health literacy) were computed. The Dutch results were compared to similar Danish and American data. The psychometric properties of the PAM 13-Dutch were generally good. The level of internal consistency is good (α = 0.88) and item-rest correlations are moderate to strong. The Dutch mean PAM score (61.3) is comparable to the American (61.9) and lower than the Danish (64.2). The test-retest reliability was moderate. The association with Health literacy was weak to moderate. The PAM-13 Dutch is a reliable instrument to measure patient activation. More research is needed into the validity of the Patient Activation Measure, especially with respect to a more comprehensive measure of Health literacy.

Characterization of the organic matter in submicron urban aerosols using a Thermo-Desorption Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (TD-PTR-TOF-MS)

NASA Astrophysics Data System (ADS)

Salvador, Christian Mark; Ho, T.-T.; Chou, Charles C.-K.; Chen, M.-J.; Huang, W.-R.; Huang, S.-H.

2016-09-01

Organic matter is the most complicated and unresolved major component of atmospheric aerosol particles. Its sources and global budget are still highly uncertain and thereby necessitate further research efforts with state-of-the-art instrument. This study employed a Thermo-Desorption Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (TD-PTR-TOF-MS) for characterization of ambient organic aerosols. First, five authentic standard substances, which include phthalic acid, levoglucosan, arabitol, cis-pinonic acid and glutaric acid, were utilized to examine the response of the instrument. The results demonstrated the linearity of the TD-PTR-TOF-MS signals against a range of mass loading of specific species on filters. However, it was found that significant fragmentation happened to those challenging compounds, although the proton-transfer-reaction (PTR) was recognized as a soft ionization technique. Consequently, quantitative characterization of aerosols with the TD-PTR-TOF-MS depended on the availability of the fragmentation pattern in mass spectra and the recovery rate with the quantification ion peak(s). The instrument was further deployed to analyze a subset of submicron aerosol samples collected at the TARO (Taipei Aerosol and Radiation Observatory) in Taipei, Taiwan during August 2013. The results were compared with the measurements from a conventional DRI thermo-optical carbon analyzer. The inter-comparison indicated that the TD-PTR-TOF-MS underestimated the mass of total organic matter (TOM) in aerosol samples by 27%. The underestimation was most likely due to the thermo-decomposition during desorption processes and fragmentation in PTR drift tube, where undetectable fragments were formed. Besides, condensation loss of low vapor pressure species in the transfer components was also responsible for the underestimation to a certain degree. Nevertheless, it was showed that the sum of the mass concentrations of the major detected ion peaks correlated strongly

Size-Segregated Aerosol Composition and Mass Loading of Atmospheric Particles as Part of the Pacific Northwest 2001(PNW2001) Air Quality Study In Puget Sound

NASA Astrophysics Data System (ADS)

Disselkamp, R. S.; Barrie, L. A.; Shutthanadan, S.; Cliff, S.; Cahill, T.

2001-12-01

In mid-August, 2001, an aircraft-based air-quality study was performed in the Puget Sound, WA, area entitled PNW2001 (http://www.pnl.gov/pnw2001). The objectives of this field campaign were the following: 1. reveal information about the 3-dimensional distribution of ozone, its gaseous precursors and fine particulate matter during weather conditions favoring air pollution; 2. derive information about the accuracy of urban and biogenic emissions inventories that are used to drive the air quality forecast models; and 3. examine the accuracy of modeled ozone concentration with that observed. In support of these efforts, we collected time-averaged ( { ~}10 minute averages), size-segregated, aerosol composition and mass-loading information using ex post facto analysis techniques of synchrotron x-ray fluorescence (s-XRF), proton induced x-ray emissions(PIXE), proton elastic scattering (PESA), and scanning transmission ion microscopy (STIM). This is the first time these analysis techniques have been used together on samples collected from aircraft using an optimized 3-stage rotating drum impactor. In our presentation, we will discuss the aerosol components in three aerosol size fractions as identified by statistical analysis of multielemental data (including total mass, H, Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Pb) and relate variations in these components to physical aerosol properties, other gaseous trace constituents and to air mass origin.

Comparison of PAM Systems for Acoustic Monitoring and Further Risk Mitigation Application.

PubMed

Ludwig, Stefan; Kreimeyer, Roman; Knoll, Michaela

2016-01-01

We present results of the SIRENA 2011 research cruises conducted by the NATO Undersea Research Centre (NURC) and joined by the Research Department for Underwater Acoustics and Geophysics (FWG), Bundeswehr Technical Centre (WTD 71) and the Universities of Kiel and Pavia. The cruises were carried out in the Ligurian Sea. The main aim of the FWG was to test and evaluate the newly developed towed hydrophone array as a passive acoustic monitoring (PAM) tool for risk mitigation applications. The system was compared with the PAM equipment used by the other participating institutions. Recorded sounds were used to improve an automatic acoustic classifier for marine mammals, and validated acoustic detections by observers were compared with the results of the classifier.

Plasma peptidylglycine alpha-amidating monooxygenase (PAM) and ceruloplasmin are affected by age and copper status in rats and mice

PubMed Central

Prohaska, Joseph R.; Broderius, Margaret

2009-01-01

In an attempt to identify a sensitive and improved marker of mammalian copper status during neonatal development experiments compared two plasma cuproenzymes, peptidylglycine α-amidating monooxygenase (PAM ), an enzyme involved in peptide posttranslational activation, to ceruloplasmin (Cp), a ferroxidase involved in iron mobilization. Dietary Cu deficiency (Cu−) was studied in dams and offspring at postnatal age 3 (P3), P12, and P28. Rodent Cp activity rose during lactation whereas PAM activity fell. Reduction in Cp activity was more severe than reduction in PAM activity in Cu− offspring and dams. Cp activity was greater in rats than mice whereas PAM activity was similar in adults but greater in mouse than rat pups. Both cuproenzymes changed during neonatal development and when dietary copper was limiting. With proper controls, each enzyme can be used to assess copper status. PMID:16448835

PAM-4 delivery based on pre-distortion and CMMA equalization in a ROF system at 40 GHz

NASA Astrophysics Data System (ADS)

Zhou, Wen; Zhang, Jiao; Han, Xifeng; Kong, Miao; Gou, Pengqi

2018-06-01

In this paper, we proposed a PAM-4 delivery in a ROF system at 40-GHz. PAM-4 transmission data can be generated via look-up table (LUT) pre-distortion, then delivered over 25km single-mode fiber and 0.5m wireless link. At the receiver side, the received signal can be processed with cascaded multi-module algorithm (CMMA) equalization to improve the decision precision. Our measured results show that 10Gbaud PAM-4 transmission in a ROF system at 40-GHz can be achieved with BER of 1.6 × 10-3. To our knowledge, this is the first time to introduce LUT pre-distortion and CMMA equalization in a ROF system to improve signal performance.

[Size distributions of aerosol during the Spring Festival in Nanjing].

PubMed

Wang, Hong-Lei; Zhu, Bin; Shen, Li-Juan; Liu, Xiao-Hui; Zhang, Ze-Feng; Yang, Yang

2014-02-01

In order to investigate the firework burning impacts on spectrum distribution of atmospheric aerosol during the Spring Festival in Nanjing, number concentration and mass concentration of aerosol as well as mass concentration of gas pollutants were measured during January 19-31, 2012. The results indicated that the concentration of aerosol between 10-20 nm decreased, aerosol concentration in the range of 50-100 nm, 100-200 nm and 200-500 nm increased during the firework burning period comparing to those during the non-burning period. However, there was no obvious variation for aerosol between 20-50 nm and 0.5-10 microm. The spectrum distribution of number concentration was bimodal during the non-burning period and unimodal during the burning period, with the peak value shifting to large diameter section. The mass concentration presented a bimodal distribution, the value of PM2.5/PM10 and PM10/PM10 increased by 10% during the burning period. The firework burning events had big influence on the density of aerosol between 1.0-2.1 microm.

Polar and non-polar organic aerosols from large-scale agricultural-waste burning emissions in Northern India: Implications to organic mass-to-organic carbon ratio.

PubMed

Rajput, Prashant; Sarin, M M

2014-05-01

This study focuses on characteristics of organic aerosols (polar and non-polar) and total organic mass-to-organic carbon ratio (OM/OC) from post-harvest agricultural-waste (paddy- and wheat-residue) burning emissions in Northern India. Aerosol samples from an upwind location (Patiala: 30.2°N, 76.3°E) in the Indo-Gangetic Plain were analyzed for non-polar and polar fractions of organic carbon (OC1 and OC2) and their respective mass (OM1 and OM2). On average, polar organic aerosols (OM2) contribute nearly 85% of the total organic mass (OM) from the paddy- and wheat-residue burning emissions. The water-soluble-OC (WSOC) to OC2 ratio, within the analytical uncertainty, is close to 1 from both paddy- and wheat-residue burning emissions. However, temporal variability and relatively low WSOC/OC2 ratio (Av: 0.67±0.06) is attributed to high moisture content and poor combustion efficiency during paddy-residue burning, indicating significant contribution (∼30%) of aromatic carbon to OC2. The OM/OC ratio for non-polar (OM1/OC1∼1.2) and polar organic aerosols (OM2/OC2∼2.2), hitherto unknown for open agricultural-waste burning emissions, is documented in this study. The total OM/OC ratio is nearly identical, 1.9±0.2 and 1.8±0.2, from paddy- and wheat-residue burning emissions. Copyright © 2013 Elsevier Ltd. All rights reserved.

An aerosol climatology for a rapidly growing arid region (southern Arizona): Major aerosol species and remotely sensed aerosol properties

NASA Astrophysics Data System (ADS)

Sorooshian, Armin; Wonaschütz, Anna; Jarjour, Elias G.; Hashimoto, Bryce I.; Schichtel, Bret A.; Betterton, Eric A.

2011-10-01

This study reports a comprehensive characterization of atmospheric aerosol particle properties in relation to meteorological and back trajectory data in the southern Arizona region, which includes two of the fastest growing metropolitan areas in the United States (Phoenix and Tucson). Multiple data sets (MODIS, AERONET, OMI/TOMS, MISR, GOCART, ground-based aerosol measurements) are used to examine monthly trends in aerosol composition, aerosol optical depth (AOD), and aerosol size. Fine soil, sulfate, and organics dominate PM2.5 mass in the region. Dust strongly influences the region between March and July owing to the dry and hot meteorological conditions and back trajectory patterns. Because monsoon precipitation begins typically in July, dust levels decrease, while AOD, sulfate, and organic aerosol reach their maximum levels because of summertime photochemistry and monsoon moisture. Evidence points to biogenic volatile organic compounds being a significant source of secondary organic aerosol in this region. Biomass burning also is shown to be a major contributor to the carbonaceous aerosol budget in the region, leading to enhanced organic and elemental carbon levels aloft at a sky-island site north of Tucson (Mt. Lemmon). Phoenix exhibits different monthly trends for aerosol components in comparison with the other sites owing to the strong influence of fossil carbon and anthropogenic dust. Trend analyses between 1988 and 2009 indicate that the strongest statistically significant trends are reductions in sulfate, elemental carbon, and organic carbon, and increases in fine soil during the spring (March-May) at select sites. These results can be explained by population growth, land-use changes, and improved source controls.

Mapping PAM4 (clivatuzumab), a monoclonal antibody in clinical trials for early detection and therapy of pancreatic ductal adenocarcinoma, to MUC5AC mucin.

PubMed

Gold, David V; Newsome, Guy; Liu, Donglin; Goldenberg, David M

2013-11-20

PAM4, an antibody that has high specificity for pancreatic ductal adenocarcinoma (PDAC), compared to normal pancreas, benign lesions of the pancreas, and cancers originating from other tissues, is being investigated as a biomarker for early detection, as well as antibody-targeted imaging and therapy. Therefore, the identity of the antigen bound by this monoclonal antibody (MAb) can provide information leading to improved use of the antibody. Prior results suggested the antigen is a mucin-type glycoprotein rich in cysteine disulfide bridges that provide stable conformation for the PAM4-epitope. Indirect and sandwich enzyme immunoassays (EIA) were performed to compare and contrast the reactivity of PAM4 with several anti-mucin antibodies having known reactivity to specific mucin species (e.g., MUC1, MUC4, MUC5AC, etc.). Studies designed to block reactivity of PAM4 with its specific antigen also were performed. We demonstrate that MAbs 2-11 M1 and 45 M1, each reactive with MUC5AC, are able to provide signal in a heterologous sandwich immunoassay where PAM4 is the capture antibody. Further, we identify MAbs 21 M1, 62 M1, and 463 M1, each reactive with MUC5AC, as inhibiting the reaction of PAM4 with its specific epitope. MAbs directed to MUC1, MUC3, MUC4, MUC16 and CEACAM6 are not reactive with PAM4-captured antigen, nor are they able to block the reaction of PAM4 with its antigen. These data implicate MUC5AC as a specific mucin species to which PAM4 is reactive. Furthermore, this realization may allow for the improvement of the current PAM4 serum-based immunoassay for detection of early-stage PDAC by the application of anti-MUC5AC MAbs as probes in this sandwich EIA.

Changes in ground-level PM mass concentration and column aerosol optical depth over East Asia during 2004-2014

NASA Astrophysics Data System (ADS)

Nam, J.; Kim, S. W.; Park, R.; Yoon, S. C.; Sugimoto, N.; Park, J. S.; Hong, J.

2015-12-01

Multi-year records of moderate resolution imaging spectroradiometer (MODIS), ground-level particulate matter (PM) mass concentration, cloud-aerosol lidar with orthogonal polarization (CALIOP), and ground-level lidar were analyzed to investigate seasonal and annual changes of aerosol optical depth (AOD) and PM mass concentration over East Asia. Least mean square fit method is applied to detect the trends and their magnitudes for each selected regions and stations. Eleven-year MODIS measurements show generally increasing trends in both AOD (1.18 % yr-1) and Ångström exponent (0.98 % yr-1), especially over the east coastal industrialized region in China. Monthly variation of AOD show maximum value at April-July, which were related to the progress of summer monsoon rain band and stationary continental air mass on the northeast of Asia. Increasing trends of AOD were found for eight cites in China (0.80 % yr-1) and Seoul site, Korea (0.40 % yr-1), whereas no significant change were shown in Gosan background site (0.04 % yr-1) and decreasing trend at five background sites in Japan (-0.42 % yr-1). Contrasting to AOD trend, all fifteen sites in China (-1.28 % yr-1), Korea (-2.77 % yr-1), and Japan (-2.03 % yr-1) showed decreasing trend of PM10 mass concentration. Also, PM2.5 mass concentration at Beijing, Seoul, Rishiri, and Oki show significant decreasing trend of -1.16 % yr-1. To further discuss the opposite trend of surface PM mass concentration and column AOD, we investigate vertical aerosol profile from lidar measurements. AOD estimated for planetary boundary layer (surface~1.5 km altitude; AODPBL) from CALIOP measurements over East China show decreasing trend of -1.71 % yr-1 over the period of 2007-2014, wherever AOD estimated for free troposphere (1.5 km~5 km altitude; AODFT) show increasing trend of 2.92 % yr-1. In addition, ground-level lidar measurements in Seoul show decreasing AODPBL trend of -2.57 % yr-1, whereas, AODFT show no significant change (-0.44 % yr

Comprehensive chemical comparison of fuel composition and aerosol particles emitted from a ship diesel engine by gas chromatography atmospheric pressure chemical ionisation ultra-high resolution mass spectrometry with improved data processing routines.

PubMed

Rüger, Christopher P; Schwemer, Theo; Sklorz, Martin; O'Connor, Peter B; Barrow, Mark P; Zimmermann, Ralf

2017-02-01

The analysis of petrochemical materials and particulate matter originating from combustion sources remains a challenging task for instrumental analytical techniques. A detailed chemical characterisation is essential for addressing health and environmental effects. Sophisticated instrumentation, such as mass spectrometry coupled with chromatographic separation, is capable of a comprehensive characterisation, but needs advanced data processing methods. In this study, we present an improved data processing routine for the mass chromatogram obtained from gas chromatography hyphenated to atmospheric pressure chemical ionisation and ultra high resolution mass spectrometry. The focus of the investigation was the primary combustion aerosol samples, i.e. particulate matter extracts, as well as the corresponding fossil fuels fed to the engine. We demonstrate that utilisation of the entire transient and chromatographic information results in advantages including minimisation of ionisation artefacts and a reliable peak assignment. A comprehensive comparison of the aerosol and the feed fuel was performed by applying intensity weighted average values, compound class distribution and principle component analysis. Certain differences between the aerosol generated with the two feed fuels, diesel fuel and heavy fuel oil, as well as between the aerosol and the feed were revealed. For the aerosol from heavy fuel oil, oxidised species from the CHN and CHS class precursors of the feed were predominant, whereas the CHO x class is predominant in the combustion aerosol from light fuel oil. Furthermore, the complexity of the aerosol increases significantly compared to the feed and incorporating a higher chemical space. Coupling of atmospheric pressure chemical ionisation to gas chromatography was found to be a useful additional approach for characterisation of a combustion aerosol, especially with an automated utilisation of the information from the ultra-high resolution mass spectrometer

Two-Column Aerosol Project (TCAP) Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, Larry K

This study included the deployment of the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Mobile Facility (AMF), ARM Mobile Aerosol Observing System (MAOS) and the ARM Aerial Facility (AAF). The study was a collaborative effort involving scientists from DOE national laboratories, NOAA, NASA, and universities. The AAF and MAOS were deployed for two approximately month-long Intensive Operational Periods (IOPs) conducted in June 2012 and February 2013. Seasonal differences in the aerosol chemical and optical properties observed using the AMF, AAF, and MAOS are presented in this report. The total mass loading of aerosol is found tomore » be much greater in the summer than in the winter, with the difference associated with greater amounts of organic aerosol. The mass fraction of organic aerosol is much reduced in the winter, when sulfate is the dominant aerosol type. Surprisingly, very little sea-salt aerosol was observed in the summer. In contrast, much more sea salt aerosol was observed in the winter. The mass loading of black carbon is nearly the same in both seasons. These differences lead to a relative increase in the aerosol light absorption in the winter and an associated decrease in observed single-scattering albedo. Measurements of aerosol mixing state were made using a single-particle mass spectrometer, which showed that the majority of the summertime aerosol consisted of organic compounds mixed with various amounts of sulfate. A number of other findings are also summarized in the report, including: impact of aerosol layers aloft on the column aerosol optical depth; documentation of the aerosol properties at the AMF; differences in the aerosol properties associated with both columns, which are not systematic but reflect the complicated meteorological and chemical processes that impact aerosol as it is advected away from North America; and new instruments and data-processing techniques for measuring both

Characterization of vertical aerosol flows by single particle mass spectrometry for micrometeorological analysis