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NUCLEATION AND GROWTH OF CESIUM IODIDE aerosols

JOURNAL OF AEROSOL SCIENCE 1991年第2期22卷 135-147页

作者： BUCKLE, ER Condensation Laboratory School of Materials The University Sheffield S1 3JD U.K.

Experiments on aerosol condensation in the vapour over caesium iodide at 973-1273 K provided morphological data and size distributions to support detailed tests of recent theory. Plumes of particles were obtained by evaporating the pure salt into a flow of unreactive carrier gas. Samples of the flow in the aerosol plume were aspirated to Nuclepore filters for examination by SEM. The interior of particles was observed by transmission optical microscopy of samples collected in immersion oil. The global population was studied by connecting the chamber outlet to differential mobility particle sizing (DMPS) and aerodynamic particle sizing (APS) equipment. The evaporation rate was also measured for theoretical purposes. The particles, which were essentially spherical, showed monomodal size distributions with radii ranging between 0.1 and 4-mu-m. The mean particle size increased and the size distribution broadened with evaporation temperature. The majority of particles consisted of a clear matrix containing one or more granular inclusions. Single granules without the surrounding matrix resembled rounded prisms, suggesting that they represent centres of crystallization in the molten salt droplet. The observations support the boundary-layer model of nucleation and growth adopted in the theory. The evaporation rates indicated condensation boundary-layer thicknesses of the order of 0.1 mm, increasing with temperature. The theoretical particle sizes lie within the limits observed experimentally and show a corresponding dependence on evaporation temperature. The total concentration of particles emitted was predicted to within an order of magnitude. Evaporation at 973 K or less should lead to vapour nucleation at temperatures below the thermodynamic melting point, but the particles observed appear to nucleate as liquid. The absence of morphological change and the minor effect of evaporation temperature on layer thickness indicate that the condensation mechanisms were not influenc

关键词： aerosols

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Sources of nickel, vanadium and black carbon in aerosols in Milwaukee

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ATMOSPHERIC ENVIRONMENT 2012年 59卷 294-301页

作者： de Foy, Benjamin Smyth, Alison M. Thompson, Samantha L. Gross, Deborah S. Olson, Michael R. Sager, Nicholas Schauer, James J. St Louis Univ Dept Earth & Atmospher Sci St Louis MO 63103 USA Carleton Coll Dept Chem Northfield MN USA Univ Wisconsin Madison WI 53706 USA

Detailed analysis of the health effects of particulate matter shows that metals and black carbon have significant impacts of their own. A summer intensive study was performed in Milwaukee, Wisconsin in July and August 2010 to identify potential sources of nickel, vanadium and black carbon in the atmosphere. An Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) was used to collect single-particle mass spectra and an Aethalometer was used to measure black carbon. Comparison with the National Emissions Inventory was performed using mesoscale meteorological simulations based on the Weather Research and Forecasting model (WRF) and the Comprehensive Air-quality Model with eXtensions (CAMx). The analysis suggests that nickel and vanadium are primarily emitted by industrial point sources in the Menomonee valley and that black carbon is primarily associated with mobile sources and emissions of nitrogen oxides. Evaluation of ship emissions from the port of Milwaukee suggest that they are responsible for approximately 5% of nickel and vanadium and approximately 10% of black carbon in Milwaukee. Elevated concentrations of air pollutants were found to occur mainly during wind stagnation events suggesting that local sources dominate over regional transport. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： aerosols Black carbon Nickel Vanadium Urban air quality Emissions inventory

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Influence of aerosols on the ion-flow field under high-voltage direct current transmission lines

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IET GENERATION TRANSMISSION & DISTRIBUTION 2016年第6期10卷 1479-1485页

作者： Yi, Yong Zhang, Chuyan Chen, Zhengying Wang, Liming Tsinghua Univ Dept Elect Engn State Key Lab Power Syst Beijing 100084 Peoples R China Tsinghua Univ Grad Sch Shenzhen Shenzhen 518055 Guangdong Peoples R China

In this study, the influence of aerosols on the ion-flow field has been researched by numerical calculations and experiments. The steady-state model of ion-flow field, considering the aerosols, is developed and solved by finite-element finite-difference method. The transport model of the particles is introduced by the Lagrangian method and the motion equations are solved by the fourth-order Runge-Kutta method. In the laboratory, a reduced-scale line platform is build up to test the influence of the aerosols and used to verify the calculations. From the results of measurements and calculations, it is observed that the calculated results are in good agreement with experimental results.

关键词： HVDC power transmission power transmission lines aerosols Runge-Kutta methods finite difference methods finite element analysis aerosols ion-flow field high-voltage direct current transmission lines numerical calculations steady-state model finite-element finite-difference method Lagrangian method motion equations fourth-order Runge-Kutta method reduced-scale line platform

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Heterogeneous Hydroxyl Radical Oxidation of Isoprene-Epoxydiol-Derived Methyltetrol Sulfates: Plausible Formation Mechanisms of Previously Unexplained Organosulfates in Ambient Fine aerosols

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ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS 2020年第7期7卷 460-468页

作者： Chen, Yuzhi Zhang, Yue Lambe, Andrew T. Xu, Rongshuang Lei, Ziying Olson, Nicole E. Zhang, Zhenfa Szalkowski, Tessa Cui, Tianqu Vizuete, William Gold, Avram Turpin, Barbara J. Ault, Andrew P. Chan, Man Nin Surratt, Jason D. Univ North Carolina Chapel Hill Dept Environm Sci & Engn Gillings Sch Global Publ Hlth Chapel Hill NC 27599 USA Aerodyne Res Inc Billerica MA 01821 USA Chinese Univ Hong Kong Fac Sci Earth Syst Sci Programme Hong Kong Peoples R China Univ Michigan Sch Publ Hlth Dept Environm Hlth Sci Ann Arbor MI 48109 USA Univ Michigan Coll Literature Sci & Arts Dept Chem Ann Arbor MI 48109 USA

Methyltetrol sulfates are unique tracers for secondary organic aerosols (SOA) formed from acid-driven multiphase chemistry of isoprene-derived epoxydiols. 2-Methyltetrol sulfate diastereomers (2-MTSs) are the dominant isomers and single most-abundant SOA tracers in atmospheric fine particulate matter (PM2.5), but their atmospheric sinks remain unknown. We investigated the oxidative aging of authentic 2-MTS aerosols by gas-phase hydroxyl radicals ((OH)-O-center dot) at a relative humidity of 61 +/- 1%. The effective rate constant for this heterogeneous reaction was determined as 4.9 +/- 0.6 x 10(-13) cm(3) molecules(-1) s(-1), corresponding to an atmospheric lifetime of 16 +/- 2 days (assuming an (OH)-O-center dot concentration of 1.5 x 10(6) molecules cm(-3)). Chemical changes to 2-MTSs were monitored by hydrophilic interaction liquid chromatography interfaced to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (HILIC/ESI-HR-QTOFMS). Plausible reaction mechanisms are proposed for previously unknown OSs detected in atmospheric PM2.5 at mass-to-charge ratios (m/z) of 139 (C2H3O5S-), 155 (C2H3O6S-), 169 (C3H5O6S-), 171 (C3H7O6S-), 185 (C3H5O7S-), 199 (C4H7O7S-), 211 (C5H7O7S-), 213 (C5H9O7S-), 227 (C5H7O8S-), 229 (C5H9O8S-), and 231 (C5H11O8S-). Heterogeneous H-center dot oxidation of 2-MTSs redistributes the particulate sulfur speciation into more oxygenated/functionalized OSs, likely modifying the aerosol physicochemical properties of SOA containing 2-MTSs.

关键词： Anions aerosols Oxidation Molecular structure Particulate matter

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Spatiotemporal characteristics of aerosols in India: Observations and model simulations

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ATMOSPHERIC ENVIRONMENT 2015年 116卷 225-244页

作者： Ramachandran, S. Kedia, Sumita Sheel, Varun Phys Res Lab Space & Atmospher Sci Div Ahmadabad 380009 Gujarat India Ctr Dev Adv Comp Computat Earth Sci Grp Pune 411007 Maharashtra India

An analysis of aerosol characteristics measured using sun photometers, MODIS and MISR, and simulated using global aerosol models (GOCART and MOZART) over six distinctly different environments in India reveal significant regional and temporal variations. Model AODs are lower than measured AODs, and exhibit a winter low and summer high, while features in measured AODs differ. MODIS and MISR AODs are higher than model simulated AODs. Differences between measured and model AODs arise due to absence of seasonal cycle in model AODs which occurs mainly due to lack of proper representation of aerosol emissions and not due to meteolorogy. In model simulations dust (>40% during premonsoon) and sulfate (40% during monsoon) contribute the maximum to total AOD. Model derived single scattering albedo (SSA) is higher than measured SSA over the study locations because simulated BC is low. The inter-annual variability in model derived SSA is lower than model-observation differences in SSA. The intra-regional variation in model AODs is lower than that of MODIS AODs. Sea salt contributes similar to 10% to total AOD during monsoon only over Peninsular and west Central India. The underestimation of AODs by GOCART and MOZART and space-time differences with observations strongly favors improving the emission inventories of aerosol sources and removal mechanisms of aerosols in the models. Results from present study can serve as inputs to tune models because not only total AODs but also species AODs, and their amount need to be properly simulated in order to reduce the uncertainty in radiative and climate impact of aerosols. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： aerosols India Observations Models Aerosol optical depth Single scattering albedo Absorbing aerosol optical depth

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Characterization of few-layer graphene aerosols by laser-induced incandescence

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CARBON 2020年 167卷 870-880页

作者： Musikhin, Stanislav Fortugno, Paolo Corbin, Joel C. Smallwood, Greg J. Dreier, Thomas Daun, Kyle J. Schulz, Christof Univ Duisburg Essen Inst Combust & Gas Dynam React Fluids D-47057 Duisburg Germany Univ Duisburg Essen Ctr Nanointegrat Duisburg Essen D-47057 Duisburg Germany Univ Waterloo Dept Mech & Mechatron Engn Waterloo ON N2L 3G1 Canada Natl Res Council Canada Metrol Res Ctr Ottawa ON K1K 2E1 Canada

Gas-phase synthesis is a promising route for producing large amounts of high quality few-layer graphene (FLG) nanoparticles economically, but optimizing these processes requires a detailed understanding of the formation kinetics, which in turn demands diagnostics for characterizing this material in situ. This work reports the first laser-induced incandescence measurements on FLG aerosols. Temporallyand spectrally-resolved incandescence signals from FLG particles are measured and used to calculate pyrometric temperatures. Differences between incandescence signals and pyrometric temperatures obtained from FLG and aerosolized soot nanoaggregates are attributed to the larger absorption cross-section and specific surface area of FLG compared to soot. LII signal intensity is found to vary linearly with particle number concentration measured independently by a condensation particle counter. Overall, these results demonstrate the potential for laser-induced incandescence to measure FLG nanoparticle mass (volume) fraction and active surface area in situ, as well as to differentiate graphene from other types of carbonaceous nanomaterials online. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： aerosols

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Characterization of chemical properties of atmospheric aerosols over Anmyeon (South Korea), a super site under Global Atmosphere Watch

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JOURNAL OF ATMOSPHERIC CHEMISTRY 2010年第2-3期67卷 71-86页

作者： Park, Sung-Hwa Panicker, A. S. Lee, Dong-In Jung, Woon-Seon Jang, Sang-Min Jang, Min Kim, Dongchul Kim, Yu-Won Jeong, Harrison Pukyong Natl Univ Dept Environm Atmospher Sci Pusan 608737 South Korea Pukyong Natl Univ Atmospher Environm Res Inst Pusan 608737 South Korea Pukyong Natl Univ Interdisciplinary Program Earth Environm Engn Pusan 608737 South Korea Univ Maryland Baltimore Country Goddard Earth Sci & Technol Ctr Baltimore MD USA Univ Space Res Assoc Columbia MD USA Korea Meteorol Adm Korea Global Atmosphere Watch Ctr Seoul South Korea

This paper reports aerosol chemical properties for the first time over a Korean Global Atmosphere Watch (GAW) supersite, Anmyeon (36A degrees 32'N;126A degrees 19'E), during 2003-2004 period. Total suspended Particulates (TSP) showed significant seasonal variation with consistent higher mass concentrations during spring season (average of up to 230 A +/- 190 mu g/m(3)). PM10 also followed similar trend with higher concentrations during spring (average of up to 170 A +/- 130 mu g/m(3)) and showed reduced concentrations during summer. PM2.5 showed a significant increase during summer (average of up to 60 A +/- 25 mu g/m(3)), which could be due to the influx of fine mode sea salt aerosols associated with the Changma front (summer monsoon). Chemical composition analysis showed enhanced presence of acidic fractions, majorly contributed by sulphates (SO (4) (2-) ) and nitrates (NO (3) (-) ) in TSP, PM10 and PM2.5 during different seasons. Enhanced presence of Calcium (Ca2+) was observed during sand storm days during spring. The high correlation obtained on matrix analysis between crustal ions and acidic ions suggests that the ionic compositions over the site are mainly contributed by terrestrial sources of similar origin. The neutralization factors has been estimated to find the extend of neutralization of acidicity by main basic components, and found to have higher value for Ammonium (up to 1.1) in different seasons, indicating significant neutralization of acidic components over the region by NH (4) (+) . Back trajectory analysis has been performed during different seasons to constrain the possible sources of aerosol origin and the results are discussed in detail.

关键词： aerosols TSP PM10 PM2,(5)

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A TUNABLE IR-DIODE LASER TECHNIQUE FOR MEASURING REACTION-RATES OF HIGH-TEMPERATURE aerosols

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COMBUSTION AND FLAME 1989年第1期77卷 69-78页

作者： BRANDT, O ROTH, P Fachgebiet Verbrennung und Gasdynamik Universität Duisburg 4100 Duisburg West Germany

To determine reaction rates in high-temperature aerosols, the time-dependent mass change of the suspended particles, or changes of the gaseous reactants or products, must be measured. In the present case, the shock tube technique has been applied to produce the high-temperature reactions and a rapid scanning infrared diode laser has been used to measure the gaseous reaction products from heterogeneous gas-particle reactions. The method has been applied to sootoxygenargon mixtures where CO and CO 2 are the expected gaseous reaction products. The particle properties were determined from in situ extinction measurements at three different wavelengths, while the total particle mass suspended in the carrier gas was determined by weighing the mass of the particles in a known volume. Theoretical considerations on heterogeneous reactions and the optical diagnostic methods are given, together with preliminary results.

关键词： aerosols

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Realization of Self-Preserving Size Distribution Theory for the Evolution of Tropospheric Atmospheric aerosols through an Inverse Gaussian Distribution

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JOURNAL OF THE ATMOSPHERIC SCIENCES 2021年第7期78卷 2143-2160页

作者： Shen, J. Yu, M. Koivisto, A. J. Jiang, H. Liu, Y. Wang, L. Hussein, T. China Jiliang Univ Lab Aerosol Sci & Technol Hangzhou Peoples R China ARCHE Consulting Wondelgem Belgium Air Pollut Management Copenhagen Denmark Univ Helsinki Inst Atmospher & Earth Syst Res INAR Helsinki Finland Fudan Univ Dept Environm Sci & Engn Shanghai Peoples R China Univ Jordan Sch Sci Dept Phys Amman Jordan

The inverse Gaussian distributed method of moments (IGDMOM) was developed to analytically solve the kinetic collection equation (KCE) for the first time. Using the IGDMOM, we obtained both new analytical and asymptotic solutions to the KCE. This is shown for both the free-molecular and continuum regime collision frequency functions. The new analytical solutions are highly suitable for demonstrating the self-preserving size distribution (SPSD) theory. The SPSD theory is considered one of the most elegant research works in atmospheric science for aerosols or small cloud droplets. It was initially discovered by Friedlander and then developed by Lee with an assumption of the time-dependent lognormal size distribution function. In this study, we demonstrate that the SPSD theory of coagulating atmospheric aerosols can be presented in a simpler and more rigorous theoretical way, which is realized through the introduction of the IGDMOM for describing aerosol size distributions. Using the IGDMOM, the new formulas for the SPSD, as well as the time required for aerosols to reach the SPSD, are analytically provided and verified. Furthermore, we discover that the SPSD of atmospheric aerosols undergoing coagulation is only determined using a shape factor variable omega, which is composed of the first three moments at an initial stage. This study has critical implications for developing tropospheric atmospheric aerosol or small cloud droplet dynamics models and further verifies the SPSD theory from the viewpoint of theoretical analysis.

关键词： Atmosphere Numerical analysis modeling Model comparison aerosols particulates

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Penetration of inhaled aerosols in the bronchial tree

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MEDICAL ENGINEERING & PHYSICS 2017年 44卷 25-31页

作者： Miguel, Antonio F. Univ Evora Sch Sci & Technol Dept Phys Rua Romao Ramalho 59 P-7000671 Evora Portugal Inst Earth Sci ICT Pole Evora Evora Portugal

It has long been recognized that the pattern of particle deposition in the respiratory tree affects how far aerosols penetrate into the deeper zones of the arterial tree, and hence contribute to either their pathogenic potential or therapeutic benefit. In this paper, we introduce an anatomically-inspired model of the human respiratory tree featuring the generations 0-7 in the Weibel model of respiratory tree (i.e., the conducting zone). This model is used to study experimentally the dynamics of inhaled aerosol particles (0.5-20 mu m aerodynamic diameter), in terms of the penetration fraction of particles (i.e., the fraction of inflowing particles that leave the flow system) during typical breathing patterns. Our study underline important modifications in the penetration patterns for coarse particles compared to fine particles. Our experiments suggest a significant decrease of particle penetration for large-sized particles and higher respiratory frequencies. Dimensionless numbers are also introduced to further understand the particle penetration into the respiratory tree. A decline is seen in the penetration fraction with decreasing Reynolds number and increasing Stokes number. A simple conceptual framework is presented to provide additional insights into the findings obtained. (C) 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

关键词： Respiratory tree Lungs aerosols Deposition Penetration Breathing patterns Reynolds number Stokes number Hess-Murray law

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