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1

Ultrafine particles in cities.  

PubMed

Ultrafine particles (UFPs; diameter less than 100 nm) are ubiquitous in urban air, and an acknowledged risk to human health. Globally, the major source for urban outdoor UFP concentrations is motor traffic. Ongoing trends towards urbanisation and expansion of road traffic are anticipated to further increase population exposure to UFPs. Numerous experimental studies have characterised UFPs in individual cities, but an integrated evaluation of emissions and population exposure is still lacking. Our analysis suggests that the average exposure to outdoor UFPs in Asian cities is about four-times larger than that in European cities but impacts on human health are largely unknown. This article reviews some fundamental drivers of UFP emissions and dispersion, and highlights unresolved challenges, as well as recommendations to ensure sustainable urban development whilst minimising any possible adverse health impacts. PMID:24503484

Kumar, Prashant; Morawska, Lidia; Birmili, Wolfram; Paasonen, Pauli; Hu, Min; Kulmala, Markku; Harrison, Roy M; Norford, Leslie; Britter, Rex

2014-05-01

2

Measuring ambient acidic ultrafine particles using iron nanofilm detectors: Method development  

Microsoft Academic Search

The number concentration and size-resolved properties of acidic ultrafine particles have been observed to more closely associate with adverse health effects than do indices of total particulate mass. However, no reliable measurement techniques are currently available to quantify the number concentration and the size distribution of ambient acidic ultrafine particles. In this study, a method with the use of iron

Da-Wei Wang; Hai Guo; Chak K. Chan

2012-01-01

3

Surgical smoke and ultrafine particles  

PubMed Central

Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine (<100 nm) and accumulation mode particles (< 1 ?m). Epidemiological and toxicological studies have shown that exposure to particulate air pollution is associated with adverse cardiovascular and respiratory health effects. Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc.) was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3) of particles in the diameter range of 10 nm to 1 ?m. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure.

Bruske-Hohlfeld, Irene; Preissler, Gerhard; Jauch, Karl-Walter; Pitz, Mike; Nowak, Dennis; Peters, Annette; Wichmann, H-Erich

2008-01-01

4

Combustion derived ultrafine particles induce cytochrome P-450 expression in specific lung compartments in the developing neonatal and adult rat  

PubMed Central

Vehicle exhaust is rich in polycyclic aromatic hydrocarbons (PAH) and can be a dominant contributor to ultrafine urban particulate matter (PM). Exposure to ultrafine PM is correlated with respiratory infections and asthmatic symptoms in young children. The lung undergoes substantial growth, alveolarization, and cellular maturation within the first years of life, which may be impacted by environmental pollutants such as PM. PAHs in PM can serve as ligands for the aryl hydrocarbon receptor (AhR) that induces expression of certain isozymes in the cytochrome P-450 superfamily, such as CYP1A1 and CYP1B1, localized in specific lung cell types. Although AhR activation and induction has been widely studied, its context within PM exposure and impact on the developing lung is poorly understood. In response, we have developed a replicable ultrafine premixed flame particle (PFP) generating system and used in vitro and in vivo models to define PM effects on AhR activation in the developing lung. We exposed 7-day neonatal and adult rats to a single 6-h PFP exposure and determined that PFPs cause significant parenchymal toxicity in neonates. PFPs contain weak AhR agonists that upregulate AhR-xenobiotic response element activity and expression and are capable inducers of CYP1A1 and CYP1B1 expression in both ages with different spatial and temporal patterns. Neonatal CYP1A1 expression was muted and delayed compared with adults, possibly because of differences in the enzyme maturation. We conclude that the inability of neonates to sufficiently adapt in response to PFP exposure may, in part, explain their susceptibility to PFP and urban ultrafine PM.

Chan, Jackie K. W.; Vogel, Christoph F.; Baek, Jaeeun; Kodani, Sean D.; Uppal, Ravi S.; Bein, Keith J.; Anderson, Donald S.

2013-01-01

5

Acute pulmonary effects of ultrafine particles in rats and mice.  

PubMed

Ambient fine particles consist of ultrafine particles (< 100 nm) and accumulation-mode particles (approximately 100 to 1,000 nm). Our hypothesis that ultrafine particles can have adverse effects in humans is based on results of our earlier studies with particles of both sizes and on the finding that urban ultrafine particles can reach mass concentrations of 40 to 50 micrograms/m3, equivalent to number concentrations of 3 to 4 x 10(5) particles/cm3. The objectives of the exploratory studies reported here were to (1) evaluate pulmonary effects induced in rats and mice by ultrafine particles of known high toxicity (although not occurring in the ambient atmosphere) in order to obtain information on principles of ultrafine particle toxicology; (2) characterize the generation and coagulation behavior of ultrafine particles that are relevant for urban air; (3) study the influence of animals' age and disease status; and (4) evaluate copollutants as modifying factors. We used ultrafine Teflon (polytetrafluoroethylene [PTFE]*) fumes (count median diameter [CMD] approximately 18 nm) generated by heating Teflon in a tube furnace to 486 degrees C to evaluate principles of ultrafine particle toxicity that might be helpful in understanding potential effects of ambient ultrafine particles. Teflon fumes at ultrafine particle concentrations of approximately 50 micrograms/m3 are extremely toxic to rats when inhaled for only 15 minutes. We found that neither the ultrafine Teflon particles alone when generated in argon nor the Teflon fume gas-phase constituents when generated in air were toxic after 25 minutes of exposure. Only the combination of both phases when generated in air caused high toxicity, suggesting the existence of either radicals on the particle surface or a carrier mechanism of the ultrafine particles for adsorbed gas-phase compounds. We also found rapid translocation of the ultrafine Teflon particles across the epithelium after their deposition, which appears to be an important difference from the behavior of larger particles. Furthermore, the pulmonary toxicity of the ultrafine Teflon fumes could be prevented by adapting the animals with short 5-minute exposures on 3 days prior to a 15-minute exposure. This shows the importance of preexposure history in susceptibility to acute effects of ultrafine particles. Aging of the fresh Teflon fumes for 3.5 minutes led to a predicted coagulation resulting in particles greater than 100 nm that no longer caused toxicity in exposed animals. This result is consistent with greater toxicity of ultrafine particles compared with accumulation-mode particles. When establishing dose-response relationships for intratracheally instilled titanium dioxide (TiO2) particles of the size of the urban ultrafine particles (20 nm) and of the urban accumulation-mode particles (250 nm), we observed significantly greater pulmonary inflammatory response to ultrafine TiO2 in rats and mice. The greater toxicity of the ultrafine TiO2 particles correlated well with their greater surface area per mass. Ultrafine particles of carbon, platinum, iron, iron oxide, vanadium, and vanadium oxide were generated by electric spark discharge and characterized to obtain particles of environmental relevance for study. The CMD of the ultrafine carbon particles was approximately 26 nm, and that of the metal particles was 15 to 20 nm, with geometric standard deviations (GSDs) of 1.4 to 1.7. For ultrafine carbon particles, approximately 100 micrograms/m3 is equivalent to 12 x 10(6) particles/cm3. Homogeneous coagulation of these ultrafine particles in an animal exposure chamber occurred rapidly at 1 x 10(7) particles/cm3, so that particles quickly grew to sizes greater than 100 nm. Thus, controlled aging of ultrafine carbon particles allowed the generation of accumulation-mode carbon particles (due to coagulation growth) for use in comparative toxicity studies. We also developed a technique to generate ultrafine particles consisting of the stable isotope 13C by using 13C-graphite electrodes made in our laboratory from amorphous

Oberdörster, G; Finkelstein, J N; Johnston, C; Gelein, R; Cox, C; Baggs, R; Elder, A C

2000-08-01

6

Increased inflammation and altered macrophage chemotactic responses caused by two ultrafine particle types  

PubMed Central

Background: Ultrafine particles have been hypothesised to be an important contributing factor in the toxicity and adverse health effects of particulate air pollution (PM10) and nanoparticles are used increasingly in industrial processes. Aims: To compare the ability of ultrafine and fine particles of titanium dioxide and carbon black to induce inflammation, cause epithelial injury, and affect the alveolar macrophage clearance functions of phagocytosis and chemotaxis in vivo. Methods: Rats were instilled with fine and ultrafine carbon black and titanium dioxide. Inflammation was quantified by bronchoalveolar lavage; the ability of the macrophages to phagoytose indictor fluorescent beads and to migrate towards aC5a were determined. Results: Ultrafine particles induced more PMN recruitment, epithelial damage, and cytotoxicity than their fine counterparts, exposed at equal mass. Both ultrafine and fine particles significantly impaired the phagocytic ability of alveolar macrophages. Only ultrafine particle treatment significantly enhanced the sensitivity of alveolar macrophages to chemotact towards C5a. Conclusions: Ultrafine particles of two very different materials induced inflammation and epithelial damage to a greater extent than their fine counterparts. In general, the effect of ultrafine carbon black was greater than ultrafine titanium dioxide, suggesting that there are differences in the likely harmfulness of different types of ultrafine particle. Epithelial injury and toxicity were associated with the development of inflammation after exposure to ultrafines. Increased sensitivity to a C5a chemotactic gradient could make the ultrafine exposed macrophages more likely to be retained in the lungs, so allowing dose to accumulate.

Renwick, L; Brown, D; Clouter, A; Donaldson, K

2004-01-01

7

Measurement of fine, coarse and ultrafine particles.  

PubMed

Over the last decade a large number of measurement methods for fine, coarse and ultrafine particles have been developed to characterize ambient PM2.5 as well as personal PM2.5 exposures. These new devices will enable us to improve our understanding of factors affecting human exposure to particulate and gaseous air pollutants. A brief description and commentary on these methods is presented. Broadly, these techniques can be divided into two categories: integrated methods that are mostly filter-based, and continuous methods which are based on the measurement of physical properties of particles. In addition, we also review how our personal multipollutant sampler has been used in field studies in various locations in the United States of America. PMID:15098555

Sarnat, Jeremy A; Demokritou, Philip; Koutrakis, Petros

2003-01-01

8

Ultrafine particle characteristics in seven industrial plants.  

PubMed

Ultrafine particles are considered as a possible cause of some of the adverse health effects caused by airborne particles. In this study, the particle characteristics were measured in seven Swedish industrial plants, with a special focus on the ultrafine particle fraction. Number concentration, size distribution, surface area concentration, and mass concentration were measured at 10 different job activities, including fettling, laser cutting, welding, smelting, core making, moulding, concreting, grinding, sieving powders, and washing machine goods. A thorough particle characterization is necessary in workplaces since it is not clear yet which choice of ultrafine particle metric is the best to measure in relation to health effects. Job activities were given a different order of rank depending on what particle metric was measured. An especially high number concentration (130 x 10(3) cm(-3)) and percentage of ultrafine particles (96%) were found at fettling of aluminium, whereas the highest surface area concentration (up to 3800 mum(2) cm(-3)) as well as high PM10 (up to 1 mg m(-3)) and PM1 (up to 0.8 mg m(-3)) were found at welding and laser cutting of steel. The smallest geometric mean diameter (22 nm) was found at core making (geometric standard deviation: 1.9). PMID:19447849

Elihn, Karine; Berg, Peter

2009-07-01

9

Ultrafine particle and fiber production in microgravity  

NASA Technical Reports Server (NTRS)

In a system and method for producing ultrafine particles and ultrafine fibers of a given source material by evaporating and condensing the material in a gas atmosphere that includes inert gas. A smaller, more narrow size distribution is accomplished by producing the particles and fibers in a microgravity environment in order to reduce particle coalescence caused by convection currents. Particle coalescence also is reduced in an Earth gravity environment by controlling the convection currents. Condensed particles are collected either by providing an electrostatic field or a spatially varying magnetic field or by causing the gas to move through a filter which collects the particles. Nonferromagnetic material fibers are produced and collected by electrodes which produce an electro- static field. Ferromagnetic particles are collected by spatially varying magnetic fields.

Webb, George W. (Inventor)

1988-01-01

10

ULTRAFINE PARTICLES ON AND NEAR FREEWAYS  

EPA Science Inventory

We plan to use the concentrator to obtain concentrated samples of fine and ultrafine particles for chemical or biological assays. We plan to conduct a study of I/O ratios for vehicles under different ventilation conditions. We plan to collect large samples of particulate a...

11

Metal articles having ultrafine particles dispersed therein  

SciTech Connect

This patent describes a metal article of manufacture. It comprises: a metal selected from the group consisting of copper, silver, gold, lead, tin, nickel, zinc, cobalt, antimony, bismuth, iron, cadmium, chromium, germanium, gallium, selenium, tellurium, mercury, tungsten arsenic, manganese, iridium, indium, ruthenium, rhenium, rhodium, molybdenum, palladium, osmium and platinum; and a plurality of ultrafine particles.

Alexander, G.B.; Nadkarni, R.A.

1992-07-28

12

Polymer degradation and ultrafine particles: potential inhalation hazards for astronauts.  

PubMed

When Teflon is heated the developing fumes produce in exposed human an influenza-like syndrome (polymer fume fever) or also severe toxic effects like pulmonary edema, pneumonitis and death. The decomposition products and the resulting health effects are temperature-dependent. The toxic effects seem to be related to the ultrafine particulate fraction of the fume. To test the hypothesis that exposure to ultrafine particles results in an increased interstitialization of the particles which is accompanied by an acute pathological inflammation, rats were exposed to titanium dioxide (TiO2) particles by intratracheal instillation and by inhalation. Both acute intratracheal instillation and subchronic inhalation studies on rats show that ultrafine TiO2 particles (approximately 20 nm diameter) access the pulmonary interstitium to a larger extent than fine particles (approximately 250 nm diameter) and that they elicit an inflammatory response as indicated by PMN increase in lavaged cells. The release of ultrafine particles into the air of an enclosed environment from a thermodegradation event or from other sources is a potential hazard for astronauts. Knowing the mechanisms of action is a prerequisite for technical or medical countermeasures. PMID:11537570

Ferin, J; Oberdörster, G

1992-01-01

13

Polymer degradation and ultrafine particles: Potential inhalation hazards for astronauts  

NASA Astrophysics Data System (ADS)

When Teflon is heated the developing fumes produce in exposed humans an influenza-like syndrome (polymer fume fever) or also severe toxic effects like pulmonary edema, pneumonitis and death. The decomposition products and the resulting health effects are temperature-dependent. The toxic effects seem to be related to the ultrafine particulate fraction of the fume. To test the hypothesis that exposure to ultrafine particles results in an increased interstitialization of the particles which is accompanied by an acute pathological inflammation, rats were exposed to titanium dioxide (TiO 2) particles by intratracheal instillation and by inhalation. Both acute intratracheal instillation and subchronic inhalation studies on rats show that ultrafine TiO 2 particles (˜20 nm diameter) access the pulmonary interstitium to a larger extent than fine particles (˜250 nm diameter) and that they elicit an inflammatory response as indicated by PMN increase in lavaged cells. The release of ultrafine particles into the air of an enclosed environment from a thermodegradation event or from other sources is a potential hazard for astronauts. Knowing the mechanisms of action is a prerequisite for technical or medical countermeasures.

Ferin, J.; Oberdörster, G.

14

A chemical analyzer for charged ultrafine particles  

NASA Astrophysics Data System (ADS)

New particle formation is a frequent phenomenon in the atmosphere and of major significance for the earth's climate and human health. To date the mechanisms leading to the nucleation of particles as well as to aerosol growth are not completely understood. A lack of appropriate measurement equipment for online analysis of the chemical composition of freshly nucleated particles is one major limitation. We have developed a Chemical Analyzer for Charged Ultrafine Particles (CAChUP) capable of analyzing particles with diameters below 30 nm. A bulk of size separated particles is collected electrostatically on a metal filament, resistively desorbed and consequently analyzed for its molecular composition in a time of flight mass spectrometer. We report of technical details as well as characterization experiments performed with the CAChUP. Our instrument was tested in the laboratory for its detection performance as well as for its collection and desorption capabilities. The manual application of known masses of camphene (C10H16) to the desorption filament resulted in a detection limit between 0.5 and 5 ng, and showed a linear response of the mass spectrometer. Flow tube experiments of 25 nm diameter secondary organic aerosol from ozonolysis of alpha-pinene also showed a linear relation between collection time and the mass spectrometer's signal intensity. The resulting mass spectra from the collection experiments are in good agreement with published work on particles generated by the ozonolysis of alpha-pinene. A sensitivity study shows that the current setup of CAChUP is ready for laboratory measurements and for the observation of new particle formation events in the field.

Gonser, S. G.; Held, A.

2013-04-01

15

A chemical analyzer for charged ultrafine particles  

NASA Astrophysics Data System (ADS)

New particle formation is a frequent phenomenon in the atmosphere and of major significance for the Earth's climate and human health. To date the mechanisms leading to the nucleation of particles as well as to aerosol growth are not completely understood. A lack of appropriate measurement equipment for online analysis of the chemical composition of freshly nucleated particles is one major limitation. We have developed a Chemical Analyzer for Charged Ultrafine Particles (CAChUP) capable of analyzing particles with diameters below 30 nm. A bulk of size-separated particles is collected electrostatically on a metal filament, resistively desorbed and subsequently analyzed for its molecular composition in a time of flight mass spectrometer. We report on technical details as well as characterization experiments performed with the CAChUP. Our instrument was tested in the laboratory for its detection performance as well as for its collection and desorption capabilities. The manual application of defined masses of camphene (C10H16) to the desorption filament resulted in a detection limit between 0.5 and 5 ng, and showed a linear response of the mass spectrometer. Flow tube experiments of 25 nm diameter secondary organic aerosol from ozonolysis of alpha-pinene also showed a linear relation between collection time and the mass spectrometer's signal intensity. The resulting mass spectra from the collection experiments are in good agreement with published work on particles generated by the ozonolysis of alpha-pinene. A sensitivity study shows that the current setup of CAChUP is ready for laboratory measurements and for the observation of new particle formation events in the field.

Gonser, S. G.; Held, A.

2013-09-01

16

Thermophoresis of Ultrafine and Nanosized Particles  

NASA Astrophysics Data System (ADS)

It is shown that thermophoresis of ultrafine and nanosized particles can be calculated using an ideal gas model in a single-velocity Clausius approximation. An application of the classical approach allows determining the particle velocity and the force generated by the gas phase in the case where a temperature gradient is present in it. A good agreement with the available experimental data is obtained.

Bubenchikov, M. A.; Potekaev, A. I.; Bubenchikov, A. M.

2013-12-01

17

Concentrated ambient ultrafine particle exposure induces cardiac change in young healthy volunteers  

EPA Science Inventory

Exposure to ambient ultrafine particles has been associated with cardiopulmonary toxicity and mortality. Adverse effects specifically linked to ultrafine particles include loss of sympathovagal balance and altered hemostasis. To characterize the effects of ultrafine particles in ...

18

Effects of Exposure to Ultrafine Carbon Particles in Healthy Subjects and Subjects with Asthma.  

National Technical Information Service (NTIS)

We developed and validated a system for exposing people via a mouthpiece to carbon ultrafine particles (UFP) and assessed the deposition of UFP in the airways. We hypothesized that exposure to UFP causes airway inflammation, with activation of circulating...

M. W. Frampton M. J. Utell W. Zareba G. Oberdoerster C. Cox L. S. Huang P. E. Morrow F. E. H. Lee D. Chalupa L. M. Frasier D. M. Speers J. Stewart

2004-01-01

19

Study of fine and ultrafine particles for coal cleaning  

SciTech Connect

During the second quarter of work on this new project, critical review of the literature continued. Several new references related to gravity separation were identified and evaluated. A synopsis was assembled to summarize techniques developed by various researchers for the float/sink separation of ultrafine coal. In the reviewed literature, it was commonly concluded that substantial improvements in washability results for ultrafine coals can be obtained only through the application of dynamic (centrifugal) procedures, and through the use of dispersing aids such as ultrasound and surfactants. These results suggest the presence of physicochemical phenomena, typical of colloidal systems. In theoretical studies this quarter, the effects of Brownian motion on fine particle sedimentation have been identified and theoretically quantitated. The interaction between Brownian and gravitational forces was calculated, and a model was prepared to permit estimation of critical particle size in float/sink separations. In laboratory studies this quarter, aliquots of Upper Freeport coal were prepared and subjected to laboratory float/sink separations to investigate the relative effectiveness of static and centrifugal techniques for fine and ultrafine coal. This series will verify results of earlier work and provide a basis for comparing the effects which may result from further modifications to the separation techniques resulting from insights gained in the basic phenomena governing float/sink processes. 15 refs., 6 figs., 1 tab.

Birlingmair, D.; Buttermore, W.; Chmielewski, T.; Pollard, J.

1990-04-01

20

Response Time of Photoemission of Ultrafine Particle Thin Film.  

National Technical Information Service (NTIS)

The response time of photoemissive materials is required for detecting ultrashort duration laser pulses. In this paper, the respone time of photoemission in ultrafine particle thin film is studied, and the transit time spread (TTS) and response time of pe...

J. L. Wu L. J. Guo Q. D. Wu

1994-01-01

21

In-cabin ultrafine particle dynamics  

NASA Astrophysics Data System (ADS)

To assess the total human health risks associated with human exposure to ultrafine particle (UFP), the concentrations and fates of UFPs in the in-cabin atmospheres must be understood. In order to assess human exposure more accurately and further prevent adverse health effects from UFP exposure in the in-cabins, it is essential to gain insight into UFP transport dynamics between in-cabin and outside atmospheres and the factors that are able to affect them. In this dissertation, mathematical model are developed and formulated as tools to improve the understanding of UFP dynamics in the in-cabin atmosphere. Under three different ventilation conditions, (i) Fan off-recirculation (RC) off, (ii) Fan on-RC off, and (iii) Fan on-RC on, the average modeled UFP I/O ratios were found to be 0.40, 0.25 and 0.10, respectively, and agree with the experimental data very well. Then, analysis focused on how the factors, such as ventilation settings, vehicle speed, filtration, penetration, and deposition, affect I/O ratios in broader categories of vehicle cabin microenvironments. Ventilation is the only mechanical process of exchanging air between the in-cabin and the outside. Under condition (ii), I/O ratio that varies from 0.2 to 0.7 was proportional to the airflow rate in the range of 0-360 m3/h. Under condition (iii), the modeled I/O ratio was inversely proportional to the airflow rate from mechanical ventilation within the range of 0.15-0.45 depending on the particle size. Significant variability of the penetration factor (5˜20%) was found due to the pressure difference. A coefficient "B" was successfully introduced to account for the electric charge effect on penetration factors. The effect of penetration on the I/O ratio was then evaluated by substituting penetration factor into the model. Under condition (i), the modeled I/O ratios increased linearly, up to ˜20%, within the penetration factor range. Under condition (iii), the effect of penetration factor is less but still significant (˜10%). The most penetrating particle size was observed at ˜300 nm, where the filtration efficiency was ˜20% in this study. As the filter face velocity (0.1 m s-1 ˜ 0.5 m s-1) increased, filtration efficiency reductions were 10%-20%. As filter usage is increased, filtration efficiency enhancements were 5%-15% but mechanical airflow rate decreased ˜10%. Due to the discrepancy of filtration efficiencies, the UFP I/O ratios changes 5%-15% under condition (ii), and ˜5% under condition (iii). Vehicle speed directly affects the differential pressure between the ambient and the in-cabin environments, which determines the leakage flow rate. When there is no mechanical air supply from outside, in the vehicle (conditions (i) and (iii)), driving speed plays an important role for the air exchange resulting in a greater effect (˜8%). Under condition (ii), vehicle speed has a little effect on the I/O ratios (<5%).

Xu, Bin

22

VERSATILE AEROSOL CONCENTRATION ENRICHMENT SYSTEM (VACES) FOR SIMULTANEOUS IN VIVO AND IN VITRO EVALUATION OF TOXIC EFFECTS OF ULTRAFINE, FINE AND COARSE AMBIENT PARTICLES. PART I: DEVELOPMENT AND LABORATORY CHARACTERIZATION. (R827352C001)  

EPA Science Inventory

This study presents the development and bench-testing of a versatile aerosol concentration enrichment system (VACES) capable of simultaneously concentrating ambient particles of the coarse, fine and ultrafine size fractions for conducting in vivo and in vitro studies. The VACE...

23

Transmission electron microscopy investigation of ultrafine coal fly ash particles.  

PubMed

Ultrafine (<100 nm) ash particles in three coal fly ashes (CFA) produced by the combustion of three U.S. coals have been examined by high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), and electron diffraction. These ultrafine particles, either as primary ash particles derived directly from coal minerals or as secondary products of decomposition and vaporization-condensation processes, show quite different morphologies, compositions, and microstructures as compared to particles in coarser, micrometer-size fractions previously examined by CCSEM. An eastern U.S. bituminous CFA sample shows abundant discrete crystalline particles rich in Fe, Ti, and Al in its ultrafine ash fraction, and crystalline phases down to 10 nm size have been identified. Western U.S. low-rank CFA samples contain considerable amounts of alkaline-earth element aggregates in the form of phosphates, silicates, and sulfates and mixed species. Most of them show crystalline or crystalline plus amorphous characteristics. All three ultrafine samples also exhibit carbonaceous particles in the form of soot aggregates with primary particle size typically between 20 and 50 nm. In the western low-rank ultrafine CFAs, these carbonaceous soot particles were typically mixed or coated with multi-element inorganic species. PMID:15773488

Chen, Yuanzhi; Shah, Naresh; Huggins, Frank E; Huffman, Gerald P

2005-02-15

24

Polymer degradation and ultrafine particles - Potential inhalation hazards for astronauts  

NASA Technical Reports Server (NTRS)

To test the hypothesis that exposure to ultrafine particles results in an increased interstiatilization of the particles which is accompanied by an acute pathological inflammation, rats were exposed to titanium dioxide (TiO2) particles by intratracheal instillation and by inhalation. Both acute intratracheal instillation and subchronic inhalation studies on rats show that ultrafine TiO2 particles access the pulmonary interstitium to a larger extent than fine particles and that they elicit an inflammatory response as indicated by PMN increase in lavaged cells. The release of ultrafine particles into the air of an enclosed environment from a thermodegradation event or from other sources is a potential hazard for astronauts. Knowing the mechanisms of action is a prerequisite for technical or medical countermeasures.

Ferin, J.; Oberdoerster, G.

1992-01-01

25

Transparent magnetic fluid: preparation of YIG ultrafine particles  

Microsoft Academic Search

In order to prepare transparent magnetic fluid, yttrium iron garnet ultrafine particles ranging in size from 10 through 30 nm are synthesized by hydrolysis of metal alkoxides. Differential thermal analysis, X-ray diffraction analysis, electron micrography and magnetization measurements are carried out on these particles to investigate the calcination condition and particle sizes.

S. Taketomi; Y. Ozaki; K. Kawasaki; S. Yuasa; H. Miyajima

1993-01-01

26

Selective separation of ultra-fine particles by magnetophoresis  

SciTech Connect

The selective and-specific extraction of species of interest fiom local environmental and other sample sources are importaut fbr scientific research, industrial processes, and environmental applications. A novel process for selective separation of ultrafine particles using 'magnetophoresis' is investigated. The principle of this process is that the direction and velocity of particle movement in a magnetic field are determined by magnetic, gravitational, and drag fbrces. By controlling these fbrces, one is able to control the migration rates of different species and then magnetically fiactionate mixtures of species into discrete groups. This study demonstrated for the fist time the selective separation of various species, such as iron (111) oxide, cupric (11) oxide, samarium (In) oxide, and cerium (III) oxide, by magnetophoresis. To better understand this phenomenon, a fbrce-balance model was developed that provides a good interpretation of the experimental results.

Ying, T. (Tung-yu); Prenger, F. Coyne; Wingo, R. M. (Robert M.); Worl, L. A. (Laura A.)

2002-01-01

27

Ultrafine and respirable particles in an automotive grey iron foundry.  

PubMed

Ultrafine particle number and respirable particle mass concentrations were measured throughout an automotive grey iron foundry during winter, spring and summer using a particle concentration mapping procedure. Substantial temporal and spatial variability was observed in all seasons and attributed, in part, to the batch nature of operations, process emission variability and frequent work interruptions. The need for fine mapping grids was demonstrated, where elevations in particle concentrations were highly localized. Ultrafine particle concentrations were generally greatest during winter when incoming make-up air was heated with direct fire, natural gas burners. Make-up air drawn from roof level had elevated respirable mass and ultrafine number concentrations above ambient outdoor levels, suggesting inadvertent recirculation of foundry process emissions. Elevated respirable mass concentrations were highly localized on occasions (e.g. abrasive blasting and grinding), depended on the area within the facility where measurements were obtained, but were largely unaffected by season. Particle sources were further characterized by measuring their respective number and mass concentrations by particle size. Sources that contributed to ultrafine particles included process-specific sources (e.g. melting and pouring operations), and non-process sources (e.g. direct fire natural gas heating units, a liquid propane-fuelled sweeper and cigarette smoking) were additionally identified. PMID:18056626

Evans, Douglas E; Heitbrink, William A; Slavin, Thomas J; Peters, Thomas M

2008-01-01

28

LASER DESORPTION IONIZATION OF ULTRAFINE AEROSOL PARTICLES. (R823980)  

EPA Science Inventory

On-line analysis of ultrafine aerosol particle in the 12 to 150 nm size range is performed by laser desorption/ionization. Particles are size selected with a differential mobility analyzer and then sent into a linear time-of-flight mass spectrometer where they are ablated w...

29

Adhesion of ultrafine particles—A micromechanical approach  

Microsoft Academic Search

In particle processing and product handling of fine (d < 100m), ultrafine (d < 10m) and nanosized particles (d < 0.1m), the well-known flow problems of dry cohesive powders in process apparatuses or storage and transportation containers include bridging, channelling, widely spread residence time distribution associated with time consolidation or caking effects, chemical conversions and deterioration of bioparticles. Avalanching effects

Jürgen Tomas

2010-01-01

30

Selective separation of ultra-fine particles by magnetophoresis  

Microsoft Academic Search

The selective and-specific extraction of species of interest fiom local environmental and other sample sources are importaut fbr scientific research, industrial processes, and environmental applications. A novel process for selective separation of ultrafine particles using 'magnetophoresis' is investigated. The principle of this process is that the direction and velocity of particle movement in a magnetic field are determined by magnetic,

T. Ying; F. Coyne Prenger; R. M. Wingo; L. A. Worl

2002-01-01

31

EFFECTS OF CARBON ULTRAFINE PARTICLES ON HUMAN AIRWAY EPITHELIAL CELLS  

EPA Science Inventory

One of the leading theories concerning the toxicology of ambient particulate matter (PM) attributes health effects associated with PM inhalation to ultrafine particles (UF). UF numbers dwarf those of fine and coarse particles present in the ambient air as a result of fossil fuel ...

32

The occurrence of ultrafine particles in the specific environment of children.  

PubMed

Interest in ultrafine particles (UFP) has been increasing due to their specific physico-chemical characteristics. Ultrafine particles are those with an aerodynamic diameter of <0.1 ?m and are also commonly know as nanoparticles (0.1 ?m = 100 nm). Due to their small size UFP contribute mostly to particle number concentrations and are therefore underestimated in actual pollution measurements, which commonly measure mass concentration. Children represent the most vulnerable group in regard to particulate exposure due to their developing status and different exposures compared to adults. This review discusses the sources of ultrafine particles as well as the specific exposures of children highlighting the importance and uniqueness of this age group. PMID:22475254

Burtscher, Heinz; Schüepp, Karen

2012-06-01

33

Investigation of Surface Properties of Ultrafine Particles by Application of a Multistep Condensation Nucleus Counter  

Microsoft Academic Search

The fate of atmospheric ultrafine particles is determined by their size, chemical composition, and especially by their physical and chemical surface properties. To characterize the surface of ultrafine particles, their behavior as condensation nuclei can be used. Monodisperse ultra-fine particles with different surface structures were investigated by observing the onset of droplet formation at a fixed electrical mobility diameter. Droplet

R. Niessner; B. Daeumer; D. Klockow

1990-01-01

34

Hydrogen adsorption on ultra-fine metal-carbon composite particles  

Microsoft Academic Search

This is an investigation on the storage of hydrogen at 288?308 K on ultra-fine particles. We studied the pore structure by nitrogen adsorption at 77 K on thermal-treated ultra-fine particles with CO 2 and pristine ultra-fine particles.

Sang-Moon Lee; Satoshi Ohshima; Kunio Uchida; Motoo Yumura

2002-01-01

35

Ultrafine particle emissions from desktop 3D printers  

NASA Astrophysics Data System (ADS)

The development of low-cost desktop versions of three-dimensional (3D) printers has made these devices widely accessible for rapid prototyping and small-scale manufacturing in home and office settings. Many desktop 3D printers rely on heated thermoplastic extrusion and deposition, which is a process that has been shown to have significant aerosol emissions in industrial environments. However, we are not aware of any data on particle emissions from commercially available desktop 3D printers. Therefore, we report on measurements of size-resolved and total ultrafine particle (UFP) concentrations resulting from the operation of two types of commercially available desktop 3D printers inside a commercial office space. We also estimate size-resolved (11.5 nm-116 nm) and total UFP (<100 nm) emission rates and compare them to emission rates from other desktop devices and indoor activities known to emit fine and ultrafine particles. Estimates of emission rates of total UFPs were large, ranging from ˜2.0 × 1010 # min-1 for a 3D printer utilizing a polylactic acid (PLA) feedstock to ˜1.9 × 1011 # min-1 for the same type of 3D printer utilizing a higher temperature acrylonitrile butadiene styrene (ABS) thermoplastic feedstock. Because most of these devices are currently sold as standalone devices without any exhaust ventilation or filtration accessories, results herein suggest caution should be used when operating in inadequately ventilated or unfiltered indoor environments. Additionally, these results suggest that more controlled experiments should be conducted to more fundamentally evaluate particle emissions from a wider arrange of desktop 3D printers.

Stephens, Brent; Azimi, Parham; El Orch, Zeineb; Ramos, Tiffanie

2013-11-01

36

Traffic emission factors of ultrafine particles: effects from ambient air.  

PubMed

Ultrafine particles have a significant detrimental effect on both human health and climate. In order to abate this problem, it is necessary to identify the sources of ultrafine particles. A parameterisation method is presented for estimating the levels of traffic-emitted ultrafine particles in terms of variables describing the ambient conditions. The method is versatile and could easily be applied to similar datasets in other environments. The data used were collected during a four-week period in February 2005, in Gothenburg, as part of the Göte-2005 campaign. The specific variables tested were temperature (T), relative humidity (RH), carbon monoxide concentration (CO), and the concentration of particles up to 10 ?m diameter (PM(10)); all indicators are of importance for aerosol processes such as coagulation and gas-particle partitioning. These variables were selected because of their direct effect on aerosol processes (T and RH) or as proxies for aerosol surface area (CO and PM(10)) and because of their availability in local monitoring programmes, increasing the usability of the parameterization. Emission factors are presented for 10-100 nm particles (ultrafine particles; EF(ufp)), for 10-40 nm particles (EF(10-40)), and for 40-100 nm particles (EF(40-100)). For EF(40-100) no effect of ambient conditions was found. The emission factor equations are calculated based on an emission factor for NO(x) of 1 g km(-1), thus the particle emission factors are easily expressed in units of particles per gram of NO(x) emitted. For 10-100 nm particles the emission factor is EF(ufp) = 1.8 × 10(15) × (1 - 0.095 × CO - 3.2 × 10(-3) × T) particles km(-1). Alternative equations for the EFs in terms of T and PM(10) concentration are also presented. PMID:22858604

Janhäll, Sara; Molnar, Peter; Hallquist, Mattias

2012-09-01

37

DAILY MORTALITY AND FINE AND ULTRAFINE PARTICLES IN ERFURT, GERMANY  

EPA Science Inventory

Dr H-Erich Wichmann and colleagues at the National Research Center for Environment and Health (GSF) in Neuherberg, Germany, prospec-tively studied the association of daily mortality data with the number and mass concentrations of ultra-fine and fine particles in Erfurt, Ger...

38

Recycling concrete: An undiscovered source of ultrafine particles  

NASA Astrophysics Data System (ADS)

While concrete recycling is practiced worldwide, there are many unanswered questions in relation to ultrafine particle (UFP; Dp < 100 nm) emissions and exposure around recycling sites. In particular: (i) Does recycling produce UFPs and in what quantities? (ii) How do they disperse around the source? (iii) What impact does recycling have on ambient particle number concentrations (PNCs) and exposure? (iv) How effective are commonly used dust respirators to limit exposure? We measured size-resolved particles in the 5–560 nm range at five distances between 0.15 and 15.15 m that were generated by an experimentally simulated concrete recycling source and found that: (i) the size distributions were multimodal, with up to ˜93% of total PNC in the UFP size range; and (ii) dilution was a key particle transformation mechanism. UFPs showed a much slower decay rate, requiring ˜62% more distance to reach 10% of their initial concentration compared with their larger counterparts in the 100–560 nm size range. Compared with typical urban exposure during car journeys, exposure decay profiles showed up to ˜5 times higher respiratory deposition within 10 m of the source. Dust respirators were found to remove half of total PNC; however the removal factor for UFPs was only ˜57% of that observed in the 100–560 nm size range. These findings highlight a need for developing an understanding of the nature of the particles as well as for better control measures to limit UFP exposure.

Kumar, Prashant; Morawska, Lidia

2014-06-01

39

Land use regression model for ultrafine particles in Amsterdam.  

PubMed

There are currently no epidemiological studies on health effects of long-term exposure to ultrafine particles (UFP), largely because data on spatial exposure contrasts for UFP is lacking. The objective of this study was to develop a land use regression (LUR) model for UFP in the city of Amsterdam. Total particle number concentrations (PNC), PM10, PM2.5, and its soot content were measured directly outside 50 homes spread over the city of Amsterdam. Each home was measured during one week. Continuous measurements at a central urban background site were used to adjust the average concentration for temporal variation. Predictor variables (traffic, address density, land use) were obtained using geographic information systems. A model including the product of traffic intensity and the inverse distance to the nearest road squared, address density, and location near the port explained 67% of the variability in measured PNC. LUR models for PM2.5, soot, and coarse particles (PM10, PM2.5) explained 57%, 76%, and 37% of the variability in measured concentrations. Predictions from the PNC model correlated highly with predictions from LUR models for PM2.5, soot, and coarse particles. A LUR model for PNC has been developed, with similar validity as previous models for more commonly measured pollutants. PMID:21158386

Hoek, Gerard; Beelen, Rob; Kos, Gerard; Dijkema, Marieke; van der Zee, Saskia C; Fischer, Paul H; Brunekreef, Bert

2011-01-15

40

Modeling the Burning Rate Enhancement of a Propellant Containing Ultrafine Particles  

NASA Astrophysics Data System (ADS)

Burning laws for ultrafine particles have been used in previous work to develop models for the burning of single and agglomerated particles. These ultrafine particles are usually reactive metal particles. In a rocket propellant, aluminum particles are often added to other energetic materials to enhance the burning rate and increase the energy released. In this effort, the laws describing the burning of metal particles and those describing the burning of energetic materials will both be coupled into a model for deriving the surface regression rate of the burning rocket propellant. Also from this model, an enhancement factor will be derived for the increase in the burning rate of a propellant when the size of the metal particles is decreased. Examples are shown that illustrate how this concept conforms to experimental results.

Richmond, Clinton T.

2009-12-01

41

Modeling the Burning Rate Enhancement of a Propellant Containing Ultrafine Particles  

NASA Astrophysics Data System (ADS)

Burning laws for ultrafine particles have been used in previous work to develop models for the burning of single and agglomerated particles. These ultrafine particles are usually reactive metal particles. In a rocket propellant, aluminum particles are often added to other energetic materials to enhance the burning rate and increase the energy released. In this effort, the laws describing the burning of metal particles and those describing the burning of energetic materials will both be coupled into a model for deriving the surface regression rate of the burning rocket propellant. Also from this model, an enhancement factor will be derived for the increase in the burning rate of a propellant when the size of the metal particles is decreased. Examples are shown that illustrate how this concept conforms to experimental results.

Richmond, Clinton

2009-06-01

42

Physicochemical characterization of Baizhi particles by ultrafine pulverization  

NASA Astrophysics Data System (ADS)

Baizhi, as a medicinal plant, has been demonstrated to be useful for the treatment of aches and pains in China. The physicochemical characterization of Baizhi particles is greatly influenced by ultrafine pulverization. To study the physicochemical characterization of Baizhi, the raw plant material of Baizhi was ground to 6 ?m particles by a high speed centrifugal sheering (HSCS) pulverizer. The micron particles were characterized by optical microscopy and scanning electron microscopy (SEM). Imperatorin is one of the active ingredients of Baizhi, and its extraction yield is determined to evaluate the chemical characterization of Baizhi powder. Imperatorin was analyzed by high performance liquid chromatography (HPLC). The results show that after ultrafine pulverization, the plant cell walls are broken into pieces and the extraction yield of imperatorin is increased by 11.93% compared with the normal particles.

Yang, Lian-Wei; Sun, Peng; Gai, Guo-Sheng; Yang, Yu-Fen; Wang, Yu-Rong

2011-04-01

43

Observations of ultrafine particles at Owens (dry) Lake  

NASA Astrophysics Data System (ADS)

Owens (dry) Lake is the largest natural source of PM2.5 in North America. One technique used to decrease PM2.5 levels at Owens Lake involves shallow flooding, which covers large areas of the lake bed with several inches of water. These large pools of stagnant water provide ideal conditions for bacterial growth and activity. During a field study at Owens Lake, high concentrations of ultrafine particles (?100 nm) were observed, and we hypothesize that bacterial activity in the flooded regions of the lake bed are the sources of these particles. Because ultrafine particles are known to be good cloud condensation nuclei (CCN), the presence of high number concentrations of ultrafine particles at Owens Lake could have a significant impact on cloud properties, as well as climate, for the Owens River Valley. In November 2009, particle size distributions, alongside condensation nuclei (CN) and cloud condensation nuclei (CCN) concentrations were measured at a Great Unified Basin Air Pollution Control District site on the southeast end of Owens Lake. The sampling site was located ~30 ft south of a large flooded area. Size distributions (11-600 nm) were measured using a scanning mobility particle sizer (SMPS). SMPS size distributions indicated high number concentrations (up to 10,000/cm3) of small particles (20-40 nm) occurring each afternoon throughout the study. Small particles were not observed during two dust storms, when wind speeds reached 20 m/s from the south, transported high concentrations of supermicron dust particles. Based on the SMPS data, some of these high particle concentration events can be classified as new particle formation (NPF) events, while others could possibly be ultrafine primary emissions from local sources, such as flooded areas of the lake. The timing and intensity of the NPF events varied depending on meteorological conditions, such as wind speed and direction, and relative humidity, and the availability of gas-phase precursors, namely O3 and SO2. New particle growth rates during NPF events also depended on atmospheric conditions, and varied from 2.75 - 11 nm/hr. CCN concentrations were also measured throughout the study to determine how the presence of ultrafine particles affected the cloud nucleating ability of Owens Lake particles as a whole.

Fitzgerald, E.; Moore, M. J.; Prather, K. A.

2010-12-01

44

Fluxes of Ultrafine Particles Over and In a Deciduous Forest  

NASA Astrophysics Data System (ADS)

Given the importance of forests to land surface cover and particle removal (due to the very high deposition velocities and well-developed turbulence) there is a specific need to understand removal to, and in, forests. Fluxes of size-resolved and total particle number fluxes over (at 46 m) and in (at 7 m) a deciduous forest over a 14 month period are presented based on data from two Gill 3-D WindMaster Pro sonic anemometers, an Ultrafine Condensation Particle Counter (UCPC) operated at 10 Hz and a Fast Mobility Particle Sizer (FMPS) operated at 1 Hz. Size-resolved particle profiles during the same period are measured using a separate FMPS scanning at three measurement heights across the canopy (top, middle and bottom). Three methods are being applied to derive the total number and size-resolved fluxes from the UCPC and FMPS respectively; eddy covariance, inertial dissipation and the co-spectral approach. The results are integrated with fluxes of sensible heat, momentum and carbon dioxide derived using a Licor LI-7200. Results for the total number flux concentrations and the size-resolved concentrations derived using the three different approaches applied to the above canopy sampling level show a high degree of accord, but that the eddy-covariance fluxes are generally of smaller magnitude than those derived using the spectral methods. In keeping with prior research our results show a considerable number of fluxes are characterized by upward fluxes. Further our results show distinctly different flux diurnal profiles for the nucleation versus Aitken mode particles indicating some differential control on fluxes of particles of different sizes (including a role for aerosol dynamics). This presentation will provide details regarding the experimental approach, flux and gradient estimation methodologies, diagnose the size dependence of the fluxes, and compare and contrast the canopy and ground partitioning of the particle fluxes during leaf-on and leaf-off periods.

Pryor, S. C.; Hornsby, K. E.

2013-12-01

45

Joining of silicon nitride ceramics by utilizing interlayers of ultra-fine particles.  

National Technical Information Service (NTIS)

Various tests have been performed to develop a ceramic-ceramic (C-C)joining method that utilizes ultra-fine particles (UFP) as the joining interlayer. The ceramic material to be joined is silicon nitride (Si(sub 3)N(sub 4)) and the interlayer material are...

T. Abe Y. Murakami T. Aihara H. Takeuchi A. Yamakawa

1994-01-01

46

Pulmonary toxicity study in rats with three forms of ultrafine-TiO 2 particles: Differential responses related to surface properties  

Microsoft Academic Search

Surface properties are critical to assess effects of ultrafine-TiO2 particles. The aim of this study was to assess lung toxicity in rats of newly developed, well characterized, ultrafine-TiO2 particles and compare them to TiO2 samples in two different size ranges and surface modifications. Groups of rats were intratracheally instilled with doses of 1 or 5mg\\/kg of either two ultrafine rutile

David B. Warheit; Thomas R. Webb; Kenneth L. Reed; Scott Frerichs; Christie M. Sayes

2007-01-01

47

The persistence, transport and health effects of regional ultrafine particles  

Microsoft Academic Search

Due to the multitude of health studies that have shown the ability of ultrafine particles (UFPs, DP =0.3 wt % sulfur, the resulting sulfur-containing UFPs were hydrophilic and water vapor readily condensed on the generated nuclei. Due to their increased size, UFPs tend to settle out of air streams quickly; thus, limiting their impact regime to near-roadway influence and labeling

Nicholas James Spada

2010-01-01

48

Extension of Geldart's Diagram to Fluidizable Fine and Ultrafine Particles  

NASA Astrophysics Data System (ADS)

The Geldart's diagram, which was originally based on empirical observations on beds fluidized by air at ambient conditions, has been routinely used to predict the type of gas-fluidization expected for a granular material. However, the Geldart's diagram, based on particle size and density, is not currently a useful tool to predict the fluidization behaviour of many fine and ultrafine cohesive powders. There are recent reports revealing nonbubbling fluidlike fluidization for some preconditioned fine and ultrafine powders, in contrast with the predicted unfiuidizable Geldart C behaviour according to their primary particle size. In this work we present an extension of Geldart's diagram that rationalizes the type of behaviour observed for this new class of fine and ultrafine powders. In our approach we have extended empirical criteria mostly used in the past to explain the behaviour of liquid-fluidized beds, showing that fluidization, either by liquid or gas, can be understood from a general frame. Our approach to treat gas-fluidized beds of fine cohesive particles considers particle agglomerates, grown to a size limited by the balance between interparticle force and flow shear, as effective low-density particles. In accordance with experimental observations, our diagram predicts that the nonbubbling fluidization regime can be just solidlike for slightly cohesive particles (Geldar A behaviour). When particle size is decreased, we predict the existence of a nonbubbling fluidlike regime for preconditioned powders as seen experimentally. For sufficiently small particles and/or high viscosity gases, the fluidized bed transits directly from the nonbubbling fluidlike regime to elutriation as observed in gas-fluidized beds of nanoparticles, fluidized beds of micrometric particles with high viscosity gas, and liquid-fluidized beds of moderate density large beads.

Valverde, J. M.; Castellanos, A.

2009-06-01

49

Photoemission from clean and oxygen-covered ultrafine nickel particles  

NASA Astrophysics Data System (ADS)

Ultrafine nickel particles are produced in ultrapure helium. The measured photothreshold and photoelectric yield of clean nickel particles are found to be in fairly good agreement with theoretical calculations based on a three-step model using density-of-states data of a flat surface. The photothreshold change due to oxygen adsorption on nickel particles was measured. It shows qualitatively the same behavior as on a flat surface but with a sticking coefficient that is smaller by a factor of 500 compared with the one on a flat Ni(110) surface. The formation of NiO is found to influence the experiment at high surface coverage.

Müller, U.; Ammann, M.; Burtscher, H.; Schmidt-Ott, A.

1991-10-01

50

Cluster analysis of roadside ultrafine particle size distributions  

NASA Astrophysics Data System (ADS)

This study reports the diurnal, seasonal, and annual variation of ultrafine particle size distributions in downtown Toronto. The k-means clustering algorithm was applied to five years of size-resolved data for particles with diameters less than 100 nm. Continuous particle number concentrations were measured 16 m from a major arterial roadway between March 2006 and May 2011 using a Fast Mobility Particle Sizer. Eight particle size distribution (PSD) types were identified. The PSD types exhibited distinct weekday-weekend and diurnal patterns. The relative frequency that each PSD occurred varied with season and wind direction and was correlated with other pollutants. These temporal patterns and correlation helped in elucidating the sources and processes that each of the eight PSD represent. Finally, similar PSD types were observed in residential areas located 6 and 15 km away from the central monitoring site suggesting that these PSD types may be generalizable to other sites. Identification of PSD types was found to be a valuable tool to support the interpretation of PSD data so as to elucidate the sources and processes contributing to ultrafine particle concentrations.

Sabaliauskas, Kelly; Jeong, Cheol-Heon; Yao, Xiaohong; Jun, Yun-Seok; Evans, Greg

2013-05-01

51

Examining Elemental Surface Enrichment in Ultrafine Aerosol Particles Using Analytical Scanning Transmission Electron Microscopy  

Microsoft Academic Search

The surface structure and chemistry of ultrafine aerosol particles (typically particles smaller than 100 nm in diameter) play key roles in determining physical and chemical behavior, and is relevant to fields as diverse as nanotechnology and aerosol toxicity. Analytical scanning transmission electron microscopy (STEM) is one of the few analytical methods available that is potentially capable of characterizing ultrafine particles

Andrew D. Maynard; Yasuo Ito; Ilke Arslan; Anthony T Zimmer; Nigel Browning; Alan Nicholls

2004-01-01

52

Process and apparatus for producing ultrafine explosive particles  

DOEpatents

A method and an improved eductor apparatus for producing ultrafine explosive particles is disclosed. The explosive particles, which when incorporated into a binder system, have the ability to propagate in thin sheets, and have very low impact sensitivity and very high propagation sensitivity. A stream of a solution of the explosive dissolved in a solvent is thoroughly mixed with a stream of an inert nonsolvent by obtaining nonlaminar flow of the streams by applying pressure against the flow of the nonsolvent stream, to thereby diverge the stream as it contacts the explosive solution, and violently agitating the combined stream to rapidly precipitate the explosive particles from the solution in the form of generally spheroidal, ultrafine particles. The two streams are injected coaxially through continuous, concentric orifices of a nozzle into a mixing chamber. Preferably, the nonsolvent stream is injected centrally of the explosive solution stream. The explosive solution stream is injected downstream of and surrounds the nonsolvent solution stream for a substantial distance prior to being ejected into the mixing chamber.

McGowan, Michael J. (Martinsburg, WV) [Martinsburg, WV

1992-10-20

53

SOURCE STRENGTHS OF ULTRAFINE AND FINE PARTICLES DUE TO COOKING WITH A GAS STOVE  

EPA Science Inventory

Cooking, particularly frying, is an important source of particles indoors. Few studies have measured a full range of particle sizes, including ultrafine particles, produced during cooking. In this study, semicontinuous instruments with fine size discriminating ability were us...

54

ULTRAFINE CARBON PARTICLES INDUCE IL-8 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS THROUGH A POST-TRANSCRIPTIONAL MECHANISM  

EPA Science Inventory

Ultrafine carbon particles induce IL-8 expression in human airway epithelial cells through a post-transcritpional mechanism Epidemiological studies suggest that ultrafine particles contribute to particulate matter (PM) - induced adverse health effects. IL-8 is an i...

55

Process for making ultra-fine ceramic particles  

DOEpatents

A process for producing ultra-fine ceramic particles in which droplets are formed from a ceramic precursor mixture containing a metal cation, a nitrogen-containing fuel, a solvent, and an anion capable of participating in an anionic oxidation-reduction reaction with the nitrogen containing fuel. The nitrogen-containing fuel contains at least three nitrogen atoms, at least one oxygen atom, and at least one carbon atom. The ceramic precursor mixture is dried to remove at least 85 weight percent of the solvent, and the dried mixture is then ignited to form a combusted powder.

Stangle, Gregory C. (Alfred, NY) [Alfred, NY; Venkatachari, Koththavasal R. (Hornell, NY) [Hornell, NY; Ostrander, Steven P. (Scotia, NY) [Scotia, NY; Schulze, Walter A. (Alfred Station, NY) [Alfred Station, NY

1995-01-01

56

EXTRAPULMONARY TRANSLOCATION OF ULTRAFINE CARBON PARTICLES FOLLOWING WHOLE-BODY INHALATION EXPOSURE OF RATS  

Microsoft Academic Search

Studies with intravenously injected ultrafine particles have shown that the liver is the major organ of their uptake from the blood circulation. Measuring translocation of inhaled ultrafine particles to extrapulmonary organs via the blood compartment is hampered by methodological difficulties (i.e., label may come off, partial solubilization) and analytical limitations (measurement of very small amounts). The objective of our pilot

Günter Oberdörster; Zachary Sharp; Viorel Atudorei; Alison Elder; Robert Gelein; Alex Lunts; Wolfgang Kreyling; Christopher Cox

2002-01-01

57

Study of ultrafine particles near a major highway with heavy-duty diesel traffic  

Microsoft Academic Search

Motor vehicle emissions usually constitute the most significant source of ultrafine particles (diameter <0.1?m) in an urban environment. Zhu et al. (J. Air Waste Manage. Assoc., 2002, accepted for publication) conducted systematic measurements of the concentration and size distribution of ultrafine particles in the vicinity of a highway dominated by gasoline vehicle. The present study compares these previous measurements with

Yifang Zhu; William C Hinds; Seongheon Kim; Si Shen; Constantinos Sioutas

2002-01-01

58

Fabrication of cast carbon steel with ultrafine TiC particles  

Microsoft Academic Search

The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the

Sang-Hoon LEE; Jin-Ju PARK; Sung-Mo HONG; Byoung-Sun HAN; Min-Ku LEE; Chang-Kyu RHEE

2011-01-01

59

A Thermal Desorption Chemical Ionization Ion Trap Mass Spectrometer for the Chemical Characterization of Ultrafine Aerosol Particles  

Microsoft Academic Search

The development of a thermal desorption chemical ionization ion trap mass spectrometer for the chemical characterization of ultrafine aerosol particles is reported and first experimental results are presented. Atmospheric particles are size-classified and collected using a unipolar charger, a radial differential mobility analyzer and an electrostatic precipitator, and analyzed after thermal desorption and chemical ionization using an ion trap mass

Andreas Held; G. Jeffrey Rathbone; James N. Smith

2009-01-01

60

Surface area of particle administered versus mass in determining the pulmonary toxicity of ultrafine and fine carbon black: comparison to ultrafine titanium dioxide  

PubMed Central

Background Nanoparticles are characterized by having a high surface area per mass. Particulate surface area has been reported to play an important role in determining the biological activity of nanoparticles. However, recent reports have questioned this relationship. This study was conducted to determine whether mass of particles or surface area of particles is the more appropriate dose metric for pulmonary toxicity studies. In this study, rats were exposed by intratracheal instillation to various doses of ultrafine and fine carbon black. At 1, 7, or 42 days post-exposure, inflammatory and cytotoxic potential of each particle type was compared on both a mass dosage (mg/rat) as well as an equal surface area dosage (cm2 of particles per cm2 of alveolar epithelium). In an additional study, the pulmonary responses to instillation of ultrafine carbon black were compared to equivalent particle surface area doses of ultrafine titanium dioxide. Results Ultrafine carbon black particles caused a dose dependent but transient inflammatory and cytotoxic response. On a mass basis, these responses were significantly (65 fold) greater than those for fine sized carbon black. However, when doses were equalized based on surface area of particles given, the ultrafine carbon black particles were only slightly (non-significantly) more inflammogenic and cytotoxic compared to the fine sized carbon black. At one day post-exposure, inflammatory potencies of the ultrafine carbon black and ultrafine titanium dioxide particles were similar. However, while the pulmonary reaction to ultrafine carbon black resolved with time, the inflammatory effects of ultrafine titanium dioxide were more persistent over a 42 day post-exposure period. Conclusion These results indicate that for low toxicity low solubility materials, surface area of particles administered rather than mass burden of particles may be a more appropriate dose metric for pulmonary toxicity studies. In addition, ultrafine titanium dioxide appears to be more bioactive than ultrafine carbon black on an equivalent surface area of particles delivered basis.

Sager, Tina M; Castranova, Vincent

2009-01-01

61

Collection efficiency of ultrafine particles by an electrostatic precipitator under DC and pulse operating modes  

Microsoft Academic Search

High particle collection efficiency in terms of particle weight\\/volume mg\\/m3 is achieved by a conventional electrostatic precipitator (ESP). However, the collection efficiencies in terms of number density for the ultrafine (particle size between 0.01-0.1 ?m) or submicrometer particles by a conventional ESP are still relatively low. Therefore, it is necessary to improve the collection efficiency for ultrafine particles. In this

Akinori Zukeran; Paul C. Looy; A. Chakrabarti; A. A. Berezin; S. Jayaram; J. D. Cross; Tairo Ito; Jen-Shih Chang

1999-01-01

62

Attempt to form ultrafine particles with hydride and amorphous structure  

NASA Astrophysics Data System (ADS)

TiH 2 particles with fcc structure can be produced in an atmosphere of reduced pressure of H 2, instead of an ordinary inactive gas, by the gas evaporation technique. The habit of the particles grown in the intermediate zone of a smoke is determined by means of electron microscope to be dodecahedral and consists of 8 {111} and 4 {100}. As in the case of Ti particles, the growth mechanism can be considered as follows: The bcc TiH 2 particles initially formed, the high temperature phase, are transformed into fcc structure, the low temperature phase, through the martensite transformation with a slight change of the habit, from the rhombic dodecahedral to simple dodecahedral. For the preparation of amorphous particles, first the quenching rate of a particle, d T/d t was estimated to be more than 10 4°C/s. The quenching rate was estimated from measurements of the temperature gradient around the evaporation source, d T/d x and the rising velocity of the particles along the convection flow of residual gas, d x/d t. The preparation of ultrafine particles of Pd 80Si 20 chosen as a test material was attempted. However, the particles showed crystalline rather than amorphous structure.

Yatsuya, S.; Yanagida, A.; Yamauchi, K.; Mihama, K.

1984-12-01

63

Exposure to inhalable, respirable, and ultrafine particles in welding fume.  

PubMed

This investigation aims to explore determinants of exposure to particle size-specific welding fume. Area sampling of ultrafine particles (UFP) was performed at 33 worksites in parallel with the collection of respirable particles. Personal sampling of respirable and inhalable particles was carried out in the breathing zone of 241 welders. Median mass concentrations were 2.48 mg m(-3) for inhalable and 1.29 mg m(-3) for respirable particles when excluding 26 users of powered air-purifying respirators (PAPRs). Mass concentrations were highest when flux-cored arc welding (FCAW) with gas was applied (median of inhalable particles: 11.6 mg m(-3)). Measurements of particles were frequently below the limit of detection (LOD), especially inside PAPRs or during tungsten inert gas welding (TIG). However, TIG generated a high number of small particles, including UFP. We imputed measurements particle counts) and for the respirable or inhalable fraction of the welding fume (expressed as their mass) remains challenging. PMID:22539559

Lehnert, Martin; Pesch, Beate; Lotz, Anne; Pelzer, Johannes; Kendzia, Benjamin; Gawrych, Katarzyna; Heinze, Evelyn; Van Gelder, Rainer; Punkenburg, Ewald; Weiss, Tobias; Mattenklott, Markus; Hahn, Jens-Uwe; Möhlmann, Carsten; Berges, Markus; Hartwig, Andrea; Brüning, Thomas

2012-07-01

64

The structure and magnetic properties of ultrafine iron particles with oxide layer  

SciTech Connect

Ultrafine iron particles (UFIPs) are promising as materials for high-density magnetic recording and ferrofluids because the superparamagnetic state in these particles develops at smaller particle sizes than in conventional magnetic materials. The basic obstacle to producing UFIPs is their high reactivity, which leads to strong oxidation of these particles. Given this, effort is being devoted to extending chemical stabilization to iron particles of the smallest size possible. One possible approach involves the formation of a thin passivating oxide layer on iron particles [1-3], for example, by atmospheric-air oxidation or by oxidation in a special atmosphere. This results in the formation of an interesting structure - an ultrafine particle whose magnetic properties exhibit a marked variation from its center to the surface. The UFIP oxidized at room temperature was shown to consist of an unoxidized {alpha}-Fe core with an average diameter of 110 {Angstrom} and a 45-{Angstrom}-thick oxide layer with a spinel-type structure. The hyperfine magnetic field at the particle core coincides with the field in an infinite sample, whereas in the oxide layer, the average magnetic field was lower. Magnetic interaction between the central region of the UFIP and the oxide layer was found to suppress superparamagnetism and to result in development of a hyperfine structure in the Moessbauer subspectrum of the oxide layer. The observed shape of the Moessbauer spectrum is related to the surface state of the oxide phase and, to some extent, to the presence of defects.

Gavrilyuk, A.G.; Sadykov, R.A. [Vereshchagin Institute of High-Pressure Physics, Moscow (Russian Federation)

1994-12-01

65

Vascular effects of ultrafine particles in persons with type 2 diabetes  

EPA Science Inventory

BACKGROUND: Diabetes confers an increased risk for cardiovascular effects of airborne particles. OBJECTIVE: We hypothesized that inhalation of elemental carbon ultrafine particles (UFP) would activate blood platelets and vascular endothelium in people with type 2 diabetes. ...

66

UPREGULATION OF TISSUE FACTOR IN HUMAN ENDOTHELIAL CELLS FOLLOWING ULTRAFINE PARTICLE EXPOSURE  

EPA Science Inventory

Epidemiology studies have linked the exposure to air pollutant particles with increased cardiovascular mortality and morbidity, but the mechanisms remain unknown. In our laboratory we have tested the hypothesis that the ultrafine fraction of ambient pollutant particles would cau...

67

UP-REGULATION OF TISSUE FACTOR IN HUMAN PULMONARY ARTERY ENDOTHELIAL CELLS AFTER ULTRAFINE PARTICLE EXPOSURE  

EPA Science Inventory

Background: Epidemiology studies have linked exposure to pollutant particles to increased cardiovascular mortality and morbidity, but the mechanisms remain unknown. Objectives: We tested the hypothesis that the ultrafine fraction of ambient pollutant particle...

68

INDOOR AND OUTDOOR ULTRA-FINE PARTICLE COUNTS IN A 1999 TWO-SEASON FRESNO, CALIFORNIA, USA ACUTE CARDIAC PANEL STUDY  

EPA Science Inventory

Indoor and Outdoor Ultrafine Particle Counts in a 1999 Two-Season Fresno, California, USA Acute Cardiac Panel Study. John Creason, Debra Walsh, Lucas Neas, US Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects R...

69

Monitoring exposure to airborne ultrafine particles in Lisbon, Portugal.  

PubMed

The aim of this study is to contribute to the assessment of exposure levels of ultrafine particles (UFP) in the urban environment of Lisbon, Portugal, due to automobile traffic, by monitoring lung-deposited alveolar surface area (resulting from exposure to UFP) in a major avenue leading to the town centre during late Spring, as well as in indoor buildings facing it. This study revealed differentiated patterns for week days and weekends, consistent with PM(2.5) and PM(10) patterns currently monitored by air quality stations in Lisbon. The observed ultrafine particulate levels could be directly related with the fluxes of automobile traffic. During a typical week, UFP alveolar deposited surface area varied between 35.0 and 89.2 µm(2)/cm(3), which is comparable with levels reported for other towns such in Germany and United States. The measured values allowed the determination of the number of UFP per cm(3), which are comparable to levels reported for Madrid and Brisbane. In what concerns outdoor/indoor levels, we observed higher levels (32-63%) outdoor, which is somewhat lower than levels observed in houses in Ontario. PMID:22642291

Gomes, João Fernando Pereira; Bordado, João Carlos Moura; Albuquerque, Paula Cristina Silva

2012-06-01

70

Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles  

SciTech Connect

In this reporting period, a study of ultra-fine iron catalyst filtration was initiated to study the behavior of ultra-fine particles during the separation of Fischer-Tropsch Synthesis (FTS) liquids filtration. The overall focus of the program is with slurry-phase FTS in slurry bubble column reactor systems. Hydrocarbon products must be separated from catalyst particles before being removed from the reactor system. An efficient wax product/catalyst separation system is a key factor for optimizing operating costs for iron-based slurry-phase FTS. Previous work has focused on catalyst particle attrition and the formation of ultra-fine iron carbide and/or carbon particles. With the current study, we are investigating how the filtration properties are affected by these chemical and physical changes of the catalyst slurry during activation/synthesis. The change of particle size during the slurry-phase FTS has monitored by withdrawing catalyst sample at different TOS. The measurement of dimension of the HRTEM images of samples showed a tremendous growth of the particles. Carbon rims of thickness 3-6 nm around the particles were observed. This growth in particle size was not due to carbon deposition on the catalyst. A conceptual design and operating philosophy was developed for an integrated wax filtration system for a 4 liter slurry bubble column reactor to be used in Phase II of this research program. The system will utilize a primary inertial hydroclone followed by a Pall Accusep cross-flow membrane. Provisions for cleaned permeate back-pulsing will be included to as a flux maintenance measure.

James K. Neathery; Gary Jacobs; Amitava Sarkar; Burtron H. Davis

2005-09-30

71

Characterization of individual fine and ultrafine particles with a real-time single particle mass spectrometer  

Microsoft Academic Search

Designed to analyze aerosols in ambient settings, the Real-Time Single Particle Mass Spectrometer (RSMS) provides a highly time-resolved measurement of the physical and chemical properties of individual fine (<2.5 mum dia.) and ultrafine (<0.1 mum dia.) particles. Understanding aerosols within this size range is crucial as these particles greatly impact both human health and the environment. Data collected by RSMS

Melissa S. Reinard

2008-01-01

72

Monodispersed Ultrafine Zeolite Crystal Particles by Microwave Hydrothermal Synthesis  

SciTech Connect

Microwave hydrothermal synthesis of zeolites is reviewed. Monodispersed ultrafine crystal particles of zeolite (Silicalite-1) have been synthesized in batch reactor vessels by microwave irradiation heating of aqueous basic silicate precursor solutions with tetra propyl ammonium hydroxide as the templating molecule. The effects of major process parameters (such as synthesis temperature, microwave heating rate, volume ratio (i.e., the volume of the initial synthesis solution over the total volume of the reactor vessel), and synthesis time on the zeolite particle characteristics are studied using a computer-controlled microwave reactor system that allows real-time monitoring and control of reaction medium temperature. The changes in the morphology, size and crystal structure of the particles are investigated using scanning electron microscope, dynamic light scattering, X-ray diffraction, and BET surface analysis. We have found that the synthesis temperature, volume ratio, and heating rate play a significant role in controlling the particle size, uniformity, and morphology. Microwave processing has generated new morphologies of zeolite particles (i.e., uniform block-shaped particles that contain mixed gel-nanocrystallites and agglomerated crystal particles) that could not be made by a conventional hydrothermal process. At higher synthesis temperature and lower volume ratio, irregular block-shaped particles were produced, whereas increasing the volume ratio promoted the formation of monodispersed single-crystal particles with uniform shape. Our results clearly demonstrate that faster microwave heating is advantageous to enhance the zeolite crystallization kinetics and produces larger-size crystal particles in shorter time. In addition, zeolite crystallization mechanisms, depending on the microwave heating rate, were also discussed.

Hu, Michael Z. [ORNL; Harris, Michael Tyrone [ORNL; Khatri, Lubna [ORNL

2008-01-01

73

Diesel Ultrafine/Fine Particle Emissions in Numbers:Statistical Modeling and Evaluation of Engine Operating Variables.  

National Technical Information Service (NTIS)

This work aims to develop statistical models for ultrafine/fine particle number emission rates from a diesel bus, to evaluate the explanatory power of engine operating variables. Emissions were recorded by using on-board instrumentation in two types of re...

O. Gao Y. Kamaria-Nakis

2009-01-01

74

Roadside measurements of ultrafine particles at a busy urban intersection.  

PubMed

A field sampling campaign on ultrafine particles (UFPs, diameter <100 nm) was conducted at a busy traffic intersection from December 2006 to June 2007 in Corpus Christi, TX. This traffic intersection consisted of South Padre Island Drive (SPID, Highway 358) and Staples Street. Traffic densities on SPID were 9102/hr and 7880/hr for weekdays and weekends, respectively. Staples Street traffic densities were 2795/hr and 2572/hr, respectively. There were approximately 3.7% heavy-duty diesel vehicles (HDDVs) on both roadways. Peak traffic flows occurred early in the morning and late in the evening during weekdays and around noon on weekends. The average UFP total number concentration collected by a condensation particle counter (CPC 3785; TSI) was 66 x 10(3) cm(-3). A direct relationship between the UFP number concentration and traffic density was observed, but the HDDV traffic density was found to be a better estimator of the UFP number concentration than total traffic density. A scanning mobility particle sizer (SMPS 3936 with DMA 3081 and CPC 3785, TSI) measuring the particle size distribution from 7 to 290 nm was rotated among four corners of the intersection. The upwind and downwind size distributions were both bimodal in shape, exhibiting a nucleation mode at 10-30 nm and a secondary mode at 50-70 nm. The highest and lowest particle concentrations were observed on the downwind and upwind sides of both roadways, respectively, indicating the importance of wind direction. Wind speed also played an important role in overall particle concentrations; UFP concentrations were inversely proportional to wind speed. A negative correlation was observed between particle number concentrations and ambient temperature. The particle number concentration was 3.5 times greater when traffic was idling at a red light than moving at a green light. PMID:19044160

Wang, Yungang; Zhu, Yifang; Salinas, Robert; Ramirez, David; Karnae, Saritha; John, Kuruvilla

2008-11-01

75

Role of the alveolar macrophage in lung injury: studies with ultrafine particles.  

PubMed Central

We conducted a series of experiments with ultrafine particles (approximately 20 nm) and larger particles (less than 200 nm) of "nuisance" dusts to evaluate the involvement of alveolar macrophages (AM) in particle-induced lung injury and particle translocation in rats. After intratracheal instillation of both ultrafine particles and larger particles of TiO2, we found a highly increased interstitial access of the ultrafine particles combined with a large acute inflammatory reaction as determined by lung lavage parameters. An additional experiment revealed that intratracheal instillation of phagocytized ultrafine TiO2 particles (inside AM) prevented both the pulmonary inflammatory reaction and the interstitial access of the ultrafine particles. Another experiment showed that the influx of polymorphonuclear cells (PMN) into the alveolar space unexpectedly decreased with higher doses of ultrafine particles, whereas alveolar epithelial permeability (protein leakage) increased. The divergence between PMN influx into the alveolar space and changes in alveolar epithelial permeability implies that they are separate events. Pulmonary inflammatory parameters determined by lung lavage analysis correlated best with the surface area of the retained particles rather than with their mass, volume, or numbers. Because higher doses resulted in an increased interstitialized fraction of particles, we suggest that inflammatory events induced by particles in the interstitial space can modify the inflammation in the alveolar space detectable by lung lavage. Our results demonstrate the dual role of AM for modifying particle-induced lung injury, i.e., both preventing such injury and contributing to it. We conclude that the increased pulmonary toxicity of ultrafine particles is related to their larger surface area and to their increased interstitial access.(ABSTRACT TRUNCATED AT 250 WORDS)

Oberdorster, G; Ferin, J; Gelein, R; Soderholm, S C; Finkelstein, J

1992-01-01

76

Cardiovascular Effects in Adults with Metabolic Syndrome Exposed to Concentrated Ultrafine Air Pollution Particles  

EPA Science Inventory

RATIONALE: Epidemiologic studies report associations between ambient air pollution particulate matter (PM) and various indices of cardiopulmonary morbidity and mortality. A leading hypothesis contends that smaller ultrafine (UF) particles induce a greater physiologic response bec...

77

Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.  

PubMed

This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers. PMID:22954401

Gomes, J F; Albuquerque, P C; Miranda, Rosa M; Santos, Telmo G; Vieira, M T

2012-09-01

78

Ultrafine nitrate particle events in Baltimore observed by real-time single particle mass spectrometry  

NASA Astrophysics Data System (ADS)

Ambient particles in Baltimore, Maryland were characterized from April through November 2002 using the real-time single particle mass spectrometer, RSMS III. When particles containing nitrate were examined, two types of ultrafine particle events were revealed: a large burst of nominally "pure" nitrate particles in the 50-90 nm size range, and a smaller (and less frequent) burst of "pure" particles in the 50-90 nm size range that grew to 110-220 nm with time. Coincident with both of these events was an increase in the number of mixed composition particles containing nitrate, suggesting that they were formed by condensation of ammonium nitrate onto pre-existing particles. Meteorological variables, particle number concentrations and continuous nitrate mass measurements were compared to the single particle data. Number and mass concentrations estimated from RSMS III correlated well with similar measurements with other techniques. Ultrafine nitrate particle events were observed during periods of low temperature and high relative humidity as expected from ammonium nitrate equilibrium considerations. During these events, the partitioning of ammonium nitrate to the particle phase strongly influenced the particle number concentration as well as the chemical composition.

Tolocka, Michael P.; Lake, Derek A.; Johnston, Murray V.; Wexler, Anthony S.

79

Synthesis and UV shielding properties of zinc oxide ultrafine particles modified with silica and trimethyl siloxane  

Microsoft Academic Search

This paper introduces a kind of ZnO ultrafine particles modified with silica and trimethyl siloxane (TMS). Thus zinc carbonate hydroxide (ZCH) as the precursor of ZnO was synthesized using chemical precipitation method, and the precursor was modified in situ with silica and TMS. The modified ZnO ultrafine particles were obtained after calcinating the modified precursors. The surface properties of the

Zhi Cao; Zhijun Zhang; Fenxia Wang; Guangzhong Wang

2009-01-01

80

Formation and growth of ultrafine particles from secondary sources in Bakersfield, California  

NASA Astrophysics Data System (ADS)

In this study, physical and chemical properties of ultrafine aerosol particles are investigated at an urban site in Bakersfield, California, during the CalNex 2010 (California Research at the Nexus of Air Quality and Climate Change) campaign in May and June. Ultrafine particle measurements include particle number size distributions by a scanning Differential Mobility Analyzer (DMA) and size resolved aerosol chemical composition determined with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). Growth events of ultrafine particles were observed on most days and had a very regular pattern. A nucleation mode centered at ˜20 nm appeared in the morning and grew to 40-100 nm throughout the day. Microphysical modeling and size-resolved HR-ToF-AMS concentrations showed that organic components provided most of the particle growth in the ultrafine mode, and sulfate provided on most days only a minor contribution to the mass of this mode. The ultrafine particle mass was largely dominated by organics (77%), and was at maximum during the afternoon. Elemental carbon (EC) and the AMS tracer C4H9+ for hydrocarbon-like organic aerosol (HOA) peaked in the early morning during rush hour, indicative of primary emissions. The fact that the particle number concentration peaked in the afternoon, when EC was at minimum, indicates that the midday increase in number concentration was likely due to new particle formation. The potential importance of solar radiation, the condensation sink of vapor on existing particles, concentrations of OH, O3, SO2, NH3, and VOCs for both condensational growth and new particle formation is evaluated based on the covariation of these parameters with ultrafine mass. The results suggest that the ultrafine particles are from secondary sources that are co-emitted or co-produced with glyoxal and formaldehyde.

Ahlm, Lars; Liu, Shang; Day, Douglas A.; Russell, Lynn M.; Weber, Robin; Gentner, Drew R.; Goldstein, Allen H.; Digangi, Josh P.; Henry, Samuel B.; Keutsch, Frank N.; Vandenboer, Trevor C.; Markovic, Milos Z.; Murphy, Jennifer G.; Ren, Xinrong; Scheller, Scott

2012-03-01

81

Formation and growth of ultrafine particles from secondary sources in Bakersfield, California  

NASA Astrophysics Data System (ADS)

In this study, physical and chemical properties of ultrafine aerosol particles are investigated at an urban site in Bakersfield, California, during the CalNex 2010 (California Research at the Nexus of Air Quality and Climate Change) campaign in May and June. Ultrafine particle measurements include particle number size distributions by a scanning Differential Mobility Analyzer (DMA) and size resolved aerosol chemical composition determined with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). Growth events of ultrafine particles were observed on most days and had a very regular pattern. A nucleation mode centered at ˜20 nm appeared in the morning and grew to 40-100 nm throughout the day. Microphysical modeling and size-resolved HR-ToF-AMS concentrations showed that organic components provided most of the particle growth in the ultrafine mode, and sulfate provided on most days only a minor contribution to the mass of this mode. The ultrafine particle mass was largely dominated by organics (77%), and was at maximum during the afternoon. Elemental carbon (EC) and the AMS tracer C4H9+ for hydrocarbon-like organic aerosol (HOA) peaked in the early morning during rush hour, indicative of primary emissions. The fact that the particle number concentration peaked in the afternoon, when EC was at minimum, indicates that the midday increase in number concentration was likely due to new particle formation. The potential importance of solar radiation, the condensation sink of vapor on existing particles, concentrations of OH, O3, SO2, NH3, and VOCs for both condensational growth and new particle formation is evaluated based on the covariation of these parameters with ultrafine mass. The results suggest that the ultrafine particles are from secondary sources that are co-emitted or co-produced with glyoxal and formaldehyde.

Ahlm, Lars; Liu, Shang; Day, Douglas A.; Russell, Lynn M.; Weber, Robin; Gentner, Drew R.; Goldstein, Allen H.; Digangi, Josh P.; Henry, Samuel B.; Keutsch, Frank N.; Vandenboer, Trevor C.; Markovic, Milos Z.; Murphy, Jennifer G.; Ren, Xinrong; Scheller, Scott

2011-11-01

82

The effect of ventilation, age, and asthmatic condition on ultrafine particle deposition in children.  

PubMed

Ultrafine particles (UFPs) contribute to health risks associated with air pollution, especially respiratory disease in children. Nonetheless, experimental data on UFP deposition in asthmatic children has been minimal. In this study, the effect of ventilation, developing respiratory physiology, and asthmatic condition on the deposition efficiency of ultrafine particles in children was explored. Deposited fractions of UFP (10-200?nm) were determined in 9 asthmatic children, 8 nonasthmatic children, and 5 nonasthmatic adults. Deposition efficiencies in adults served as reference of fully developed respiratory physiologies. A validated deposition model was employed as an auxiliary tool to assess the independent effect of varying ventilation on deposition. Asthmatic conditions were confirmed via pre-and post-bronchodilator spirometry. Subjects were exposed to a hygroscopic aerosol with number geometric mean diameter of 27-31?nm, geometric standard deviation of 1.8-2.0, and concentration of 1.2 × 10(6) particles cm(-3). Exposure was through a silicone mouthpiece. Total deposited fraction (TDF) and normalized deposition rate were 50% and 32% higher in children than in adults. Accounting for tidal volume and age variation, TDF was 21% higher in asthmatic than in non-asthmatic children. The higher health risks of air pollution exposure observed in children and asthmatics might be augmented by their susceptibility to higher dosages of UFP. PMID:22848818

Olvera, Hector A; Perez, Daniel; Clague, Juan W; Cheng, Yung-Sung; Li, Wen-Whai; Amaya, Maria A; Burchiel, Scott W; Berwick, Marianne; Pingitore, Nicholas E

2012-01-01

83

A high flow rate, very low pressure drop impactor for inertial separation of ultrafine from accumulation mode particles  

Microsoft Academic Search

This paper presents the development and evaluation of a high-volume, multiple rectangular (slit) geometry jet impactor. Operating with a preselective inlet that removes particles larger than 2.5?m in aerodynamic size, the impactor has been designed to separate ultrafine (<0.15?m) from the accumulation mode range (0.15Particles are accelerated by passing through 10 parallel slits nozzles, each 12.5cm long by 0.0125cm

Chandan Misra; Seongheon Kim; Si Shen; Constantinos Sioutas

2002-01-01

84

Characterization of individual fine and ultrafine particles with a real-time single particle mass spectrometer  

NASA Astrophysics Data System (ADS)

Designed to analyze aerosols in ambient settings, the Real-Time Single Particle Mass Spectrometer (RSMS) provides a highly time-resolved measurement of the physical and chemical properties of individual fine (<2.5 mum dia.) and ultrafine (<0.1 mum dia.) particles. Understanding aerosols within this size range is crucial as these particles greatly impact both human health and the environment. Data collected by RSMS can be used identify particle sources and atmospheric processes. RSMS was deployed to Wilmington, DE during 2005-2006 as part of E-DATAS (Enhanced Delaware Air Toxics Assessment Study), a collaboration with the Delaware Department of Natural Resources (DNREC), the Environmental Protection Agency (EPA) and Duke University. Mass spectra acquired by RSMS were compared to a Scanning Mobility Particle Sizer (SMPS) to give a quantitative estimate of the chemical composition of PM1.0 (particulate matter <1.0 mum dia.) impacting the city. A method to collect and analyze particles directly from emission stacks of industrial facilities was developed to help identify sources of PM. Single particle mass spectrometry, in general, has remained primarily a qualitative technique due to several instrumental limitations which affect the data. First, the shot-to-shot variation in the laser pulse caused inconsistencies between the mass spectra of particles with the same composition. To determine whether this variation was systematic or random, the covariance between ions was calculated for laboratory generated aerosols. Second, RSMS was found to be highly sensitive to specific chemical species such as ammonium nitrate and transition/alkali metals. When these compounds are present in a particle they dominate the mass spectra and dwarf other the signal from other components to the baseline. To explore this bias, data collected by RSMS in Wilmington, DE was compared to data also collected in Wilmington by the quantitative NanoAerosol Mass Spectrometer (NAMS). Finally, a light scattering apparatus was designed to increase the size range of particles effectively analyzed by RSMS. This improvement will allow RSMS, when compared to an independent monitor of particulate mass, to quantitatively estimate the chemical composition particles <2.5 mum dia. (PM2.5 ) in future field campaigns.

Reinard, Melissa S.

85

Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions  

SciTech Connect

The purpose of this program is to design and fabricate an experimental ultra-fine particle generation system; use this system to generate ultra-fine, iron compound, catalyst particles; and to access the ability of these ultra-fine catalyst particles to improve the performance of the solubilization stage of two-stage, catalytic-catalytic liquefaction processes. The effort applied to this program during this reporting period was devoted to experimental design and fabrication tasks.

Not Available

1991-09-01

86

Personal exposure to ultrafine particles and oxidative DNA damage.  

PubMed

Exposure to ultrafine particles (UFPs) from vehicle exhaust has been related to risk of cardiovascular and pulmonary disease and cancer, even though exposure assessment is difficult. We studied personal exposure in terms of number concentrations of UFPs in the breathing zone, using portable instruments in six 18-hr periods in 15 healthy nonsmoking subjects. Exposure contrasts of outdoor pollution were achieved by bicycling in traffic for 5 days and in the laboratory for 1 day. Oxidative DNA damage was assessed as strand breaks and oxidized purines in mononuclear cells isolated from venous blood the morning after exposure measurement. Cumulated outdoor and cumulated indoor exposures to UFPs each were independent significant predictors of the level of purine oxidation in DNA but not of strand breaks. Ambient air concentrations of particulate matter with an aerodynamic diameter of < or = 10 microm (PM10), nitrous oxide, nitrogen dioxide, carbon monoxide, and/or number concentration of UFPs at urban background or busy street monitoring stations was not a significant predictor of DNA damage, although personal UFP exposure was correlated with urban background concentrations of CO and NO2, particularly during bicycling in traffic. The results indicate that biologic effects of UFPs occur at modest exposure, such as that occurring in traffic, which supports the relationship of UFPs and the adverse health effects of air pollution. PMID:16263500

Vinzents, Peter S; Møller, Peter; Sørensen, Mette; Knudsen, Lisbeth E; Hertel, Ole; Jensen, Finn Palmgren; Schibye, Bente; Loft, Steffen

2005-11-01

87

ULTRAFINE PARTICLE DEPOSITION IN HEALTHY SUBJECTS VS. PATIENTS WTH COPD  

EPA Science Inventory

Individuals affected with chronic obstructive pulmonary disease (COPD) have increased susceptibility to adverse health effects from exposure to particulate air pollution. The dosimetry of ultrafine aerosols (diameter # 0.1 :m) is not well characterized in the healthy or diseas...

88

Evidence of high deposition of ultrafine particles at Mauna Loa Observatory  

Microsoft Academic Search

Few measurements exist for the dry deposition of ultrafine particles (diameters less than about 10 nm) under realistic field conditions. Recently refined screen-diffusion techniques have sufficient sensitivity to measure radon (222Rn) progeny under low-level outdoor conditions. Vertical gradients of ultrafine radon progeny at Mauna Loa Observatory were measured for a range of atmospheric conditions. Gradients were generally stronger, for example,

Stewart Whittlestone

1995-01-01

89

Personal Exposure to Ultrafine Particles in the Workplace: Exploring Sampling Techniques and Strategies  

Microsoft Academic Search

Recently, toxicological and epidemiological studies on health effects related to particle exposure suggest that 'ultrafine particles' (particles with an aerodynamic diameter of <100 nm) may cause severe health effects after inhalation. Although the toxicological mechanisms for these effects have not yet been explained, it is apparent that measuring exposures against mass alone is not sufficient. It is also necessary to

DERK H. BROUWER; JOSÉ H. J. GIJSBERS; MARC W. M. LURVINK

2004-01-01

90

ENHANCED TOXICITY OF CHARGED CARBON NANOTUBES AND ULTRAFINE CARBON BLACK PARTICLES  

EPA Science Inventory

Man-made carbonaceous nano-particles such as single and multi-walled carbon nano-tubes (CNT) and ultra-fine carbon black (UFCB) particles are finding increasing applications in industry, but their potential toxic effects is of concern. In aqueous media, these particles cluster in...

91

Research on ultrafine particle size measurement using small amounts of data  

NASA Astrophysics Data System (ADS)

The paper puts forward a new method of ultrafine particle size measurement using small amounts of data of a dynamic light-scattering signal, and establishes an arithmetic model of the measurement by wavelet package transform. First, through the wavelet package transform, the ultrafine particle dynamic light-scattering signals were decomposed into multifrequency bands. Then, the noise of signals of different frequency bands were removed and the power spectrum of the wavelet packet coefficients of each frequency band was calculated. Finally, the ultrafine particle size distribution information could be deduced from inversing the power spectrum. The standard polystyrene particles of 100, 300, and 400nm were measured using this method, and the inversion results indicated that this method can effectively remove noise and improve the accuracy of particle size measurement using small amounts of data.

Li, Zhenmei; Shen, Jin; Liu, Wei; Wang, Yajing

2011-08-01

92

Ultrafine particle generation by high-velocity impact of metal projectiles  

NASA Astrophysics Data System (ADS)

Ultrafine particle generation through mechanical processes was not carefully deepened so far, even if it could be related to the human health-based researches. In particular, the evaluation of ultrafine particles produced in battlefield scenarios can be useful to quantify the exposure of soldiers to particles carrying toxic heavy metals. In the present work ultrafine particle generation during high-velocity impact of metal projectiles was deepened performing symmetrical high velocity Taylor impacts of copper cylinder tests (Rod-on-Rod tests) by means of a gas-gun facility. Particle number distributions and total concentrations were measured through one-second-time resolution instruments in a chamber where impact events at different velocities were performed. Particle number generation per impact was also evaluated. Particle concentrations in the 106 part. cm-3 range were measured corresponding to particle generations higher than 1012 particles per impact, then comparable to those typical of combustion sources. Particle number distribution showed a unimodal distribution with a 10 nm mode. Summarizing, the performed experimental campaign revealed an extremely high generation of ultrafine particles from mechanical processes.

Stabile, L.; Iannitti, G.; Vigo, P.; Ruggiero, A.; Russi, A.; Buonanno, G.

2014-05-01

93

Ultrafine Particle Number Concentrations from Hybrid Urban Transit Buses: Onboard Single-Diameter Scanning Mobility Particle Sizer Measurements  

Microsoft Academic Search

Recent studies have focused on mass-based quantification of gas and particulate matter (PM) transit bus exhaust emissions under laboratory dynamometer testing conditions because transit buses frequent heavily populated areas and are major contributors to the ambient fine particles in urban regions. This study examines the ultrafine particle (particle mobility diameters of <100 >nm) number concentrations and size distributions for conventional

Derek Vikara; Britt A Holmen

2006-01-01

94

ANALYSIS OF TOTAL RESPIRATORY DEPOSITION OF INHALED ULTRAFINE PARTICLES IN ADULT SUBJECTS AT VARIOUS BREATHING PATTERNS  

EPA Science Inventory

Ultrafine particles are ubiquitous in the ambient air and their unique physicochemical characteristics may pose a potential health hazard. Accurate lung dose information is essential to assess a potential health risk to exposure to these particles. In the present study, we measur...

95

DEPOSITION DISTRIBUTION OF NANO AND ULTRAFINE PARTICLES IN HUMAN LUNGS DURING CONTROLLED MOUTH BREATHING  

EPA Science Inventory

Nano and ultrafine particles are abundant in the atmosphere and the level of human exposure to these tiny particles is expected to increase markedly as industrial activities increase manufacturing nano-sized materials. Exposure-dose relationships and site-specific internal dose a...

96

MECHANISMS BY WHICH ULTRAFINE, FINE, AND COARSE PARTICLES CAUSE ADVERSE HEALTH EFFECTS  

EPA Science Inventory

A small number of recent studies suggest that different size particles may cause different health effects. There are clearly differences in the chemical makeup of coarse, fine, and ultrafine particles, and this different chemistry may well drive different health responses. The ...

97

Influence of Dipolar Interaction on Magnetic Properties of Ultrafine Ferromagnetic Particles  

Microsoft Academic Search

We use Monte Carlo simulations to study the influence of dipolar interaction and polydispersity on the magnetic properties of single-domain ultrafine ferromagnetic particles. From the zero field cooling (ZFC)\\/field cooling (FC) simulations we observe that the blocking temperature TB clearly increases with increasing strength of interaction, but it is almost not effected by a broadening of the distribution of particle

Jesús García-Otero; Markus Porto; José Rivas; Armin Bunde

2000-01-01

98

Pulmonary and systemic effects of short-term inhalation exposure to ultrafine carbon black particles  

Microsoft Academic Search

While environmental particles are associated with mortality and morbidity related to pulmonary and cardiovascular (CV) disease, the mechanisms involved in CV health effects are not known. Changes in systemic clotting factors have been associated with pulmonary inflammation. We hypothesized that inhaled ultrafine particles result in an inflammatory response which may stimulate systemic clotting factor release. Adult male Wistar rats were

Peter S Gilmour; Axel Ziesenis; E. Rona Morrison; Mark A Vickers; Ellen M Drost; Isobel Ford; Erwin Karg; Claudia Mossa; Andreas Schroeppel; George A Ferron; Joachim Heyder; Michael Greaves; William MacNee; Kenneth Donaldson

2004-01-01

99

White-light Detection for Nanoparticle Sizing with the TSI Ultrafine Condensation Particle Counter  

Microsoft Academic Search

Several of the most common methods for measuring nanoparticle size distributions employ the ultrafine condensation particle counter (UCPC) for detection purposes. Among these methods, the pulse height analysis (PHA) technique, in which the optical response of the UCPC detector is related to initial particle diameter in the 3–10?nm range, prevails in applications where fast sampling is required or for which

William D. Dick; Peter H. McMurry; Rodney J. Weber; Frederick R. Quant

2000-01-01

100

OXIDATIVE STRESS AND LIPID MEDIATORS INDUCED IN ALVEOLAR MACHROPHAGES BY ULTRAFINE PARTICLES  

EPA Science Inventory

In ambient aerosols, ultrafine particles (UFP) and their agglomerates are considered to be major factors contributing to adverse health effects. Reactivity of agglomerated UFP of elemental carbon (EC), Printex 90, Printex G, and diesel exhaust particles (DEP) was evaluated by the...

101

The Effect of Fuel Type and Aftertreatment Method on Ultrafine Particle Emissions from a Heavy-Duty Diesel Engine  

Microsoft Academic Search

Two potential strategies for reducing diesel emissions are exhaust aftertreatment and the use of reformulated or alternative fuels. Little is yet known about the impact on ultrafine particle emissions of combining exhaust aftertreatment with such increasingly common fuels. This paper reports ultrafine particle size distribution measurements for a study in which the impact of such fuels on emissions from a

Brian P. Frank; Shida Tang; Thomas Lanni; Jillian Grygas; Greg Rideout; Norman Meyer; Chris Beregszaszy

2007-01-01

102

Association of particulate air pollution and acute mortality: involvement of ultrafine particles?  

NASA Technical Reports Server (NTRS)

Recent epidemiological studies show an association between particulate air pollution and acute mortality and morbidity down to ambient particle concentrations below 100 micrograms/m3. Whether this association also implies a causality between acute health effects and particle exposure at these low levels is unclear at this time; no mechanism is known that would explain such dramatic effects of low ambient particle concentrations. Based on results of our past and most recent inhalation studies with ultrafine particles in rats, we propose that such particles, that is, particles below approximately 50 nm in diameter, may contribute to the observed increased mortality and morbidity In the past we demonstrated that inhalation of highly insoluble particles of low intrinsic toxicity, such as TiO2, results in significantly increased pulmonary inflammatory responses when their size is in the ultrafine particle range, approximately 20 nm in diameter. However, these effects were not of an acute nature and occurred only after prolonged inhalation exposure of the aggregated ultrafine particles at concentrations in the milligrams per cubic meter range. In contrast, in the course of our most recent studies with thermodegradation products of polytetrafluoroethylene (PTFE) we found that freshly generated PTFE fumes containing singlet ultrafine particles (median diameter 26 nm) were highly toxic to rats at inhaled concentrations of 0.7-1.0 x 10(6) particles/cm3, resulting in acute hemorrhagic pulmonary inflammation and death after 10-30 min of exposure. We also found that work performance of the rats in a running wheel was severely affected by PTFE fume exposure. These results confirm reports from other laboratories of the highly toxic nature of PTFE fumes, which cannot be attributed to gas-phase components of these fumes such as HF, carbonylfluoride, or perfluoroisobutylene, or to reactive radicals. The calculated mass concentration of the inhaled ultrafine PTFE particles in our studies was less than 60 micrograms/m3, a very low value to cause mortality in healthy rats. Aging of the fumes with concomitant aggregation of the ultrafine particles significantly decreases their toxicity. Since ultrafine particles are always present in the urban atmosphere, we suggest that they play a role in causing acute lung injury in sensitive parts of the population.

Oberdorster, G.; Gelein, R. M.; Ferin, J.; Weiss, B.; Clarkson, T. W. (Principal Investigator)

1995-01-01

103

Spatial distributions of ultrafine particles and their behavior and chemical composition in relation to roadside sources  

NASA Astrophysics Data System (ADS)

Vertical and horizontal distributions of the chemical components of ultrafine particles (UFP; <0.1 ?m) in relation to roadside sources were investigated by using a newly developed PM 0.1 collection system with a UFP impactor filter (50% cut-off, 0.1 ?m; air flow rate, 40.0 L min -1). UFP were measured at a suburban roadside, at two background sites in Saitama (summer 2007 and winter 2008), and at two levels on a high-rise building in Tokyo (summer and winter 2005). The results from the high-rise building showed that ultrafine elemental carbon from vehicle exhaust can reach the upper atmosphere regardless of season because of the high diffusivity of UFP. The total concentrations of the carbonaceous and ionic components at all sites except the roadside site in summer were mostly within the same range. Therefore, UFP diffuse both vertically and horizontally, and its chemical components are distributed uniformly. The UFP composition in summer reflected not only the vehicle exhaust contribution but also photochemical formation, especially at the low-elevation sites, where the samplers were installed several meters above ground level. The results also showed that ionic components contributed to increases in the UFP levels.

Kudo, Shinji; Sekiguchi, Kazuhiko; Kim, Kyung Hwan; Sakamoto, Kazuhiko

2011-11-01

104

Collection efficiency of ultrafine particles by an electrostatic precipitator under DC and pulse operating modes  

Microsoft Academic Search

High particle collection efficiency in terms of particle weight volume mg\\/m3 is well achieved by a conventional electrostatic precipitator (ESP). However, the collection efficiencies in terms of number density for the ultrafine (particle size between 0.01 to 0.1 ?m) or submicron particles by a conventional ESP are still relatively low. Therefore, it is necessary to improve the collection efficiency for

Akinori Zukeran; Paul C. Looy; A. Chakrabarti; Alexander A. Berezin; Shesha Jayaram; J. Cross; T. Ito; Jen Shih Chang

1997-01-01

105

SEPARATION OF FISCHER-TROPSCH WAX PRODUCTS FROM ULTRAFINE IRON CATALYST PARTICLES  

SciTech Connect

In this reporting period, a fundamental filtration study was started to investigate the separation of Fischer-Tropsch Synthesis (FTS) liquids from iron-based catalyst particles. Slurry-phase FTS in slurry bubble column reactor systems is the preferred mode of production since the reaction is highly exothermic. Consequently, heavy wax products must be separated from catalyst particles before being removed from the reactor system. Achieving an efficient wax product separation from iron-based catalysts is one of the most challenging technical problems associated with slurry-phase FTS. The separation problem is further compounded by catalyst particle attrition and the formation of ultra-fine iron carbide and/or carbon particles. Existing pilot-scale equipment was modified to include a filtration test apparatus. After undergoing an extensive plant shakedown period, filtration tests with cross-flow filter modules using simulant FTS wax slurry were conducted. The focus of these early tests was to find adequate mixtures of polyethylene wax to simulate FTS wax. Catalyst particle size analysis techniques were also developed. Initial analyses of the slurry and filter permeate particles will be used by the research team to design improved filter media and cleaning strategies.

James K. Neathery; Gary Jacobs; Burtron H. Davis

2004-03-31

106

Electrocoagulation and separation of aqueous suspensions of ultrafine particles  

Microsoft Academic Search

Conventional methods for the removal of suspended ultrafine particulates in industrial effluents and wastewater treatment frequently involve the bulk addition of inorganic coagulants (e.g. aluminum or ferric salts). This electrolytic dosing is followed by sedimentation to obtain a clarified supernatant liquid. The increased size of the coagulated material facilitates subsequent solid-liquid separation processes such as filtration.An alternative separation treatment for

Michael J. Matteson; Regina L. Dobson; Robert W. Glenn; Nagesh S. Kukunoor; William H. Waits; Eric J. Clayfield

1995-01-01

107

Effect of Working Fluid on Sub2 nm Particle Detection with a Laminar Flow Ultrafine Condensation Particle Counter  

Microsoft Academic Search

The effect of working fluid on size-dependent activation efficiencies with the laminar flow ultrafine condensation particle counter described by Stolzenburg and McMurry (1991) was studied theoretically and experimentally. Criteria considered include tendency to avoid homogeneous nucleation within the condenser and toxicity. The working fluids that were identified have vapor pressures below that of butanol, so particles grow to smaller sizes

Kenjiro Iida; Mark R. Stolzenburg; Peter H. McMurry

2009-01-01

108

Characterization of ultrafine and fine particles at a site near the Great Smoky Mountains National Park  

NASA Astrophysics Data System (ADS)

Continuous measurements were taken during a 22-day campaign held in the summer of 2000 at a site close to the Great Smoky Mountains National Park in eastern Tennessee. The campaign was conducted to investigate the relationships between ultrafine/fine particles and gaseous species observed. A varimax-rotation factor analysis was performed to explore the relationship of the fine and ultrafine particle number concentrations, the gaseous species concentration, the mean wind speed, and the solar radiation. A 6-factor model was found to best resolve 79.7% of the variability embedded in the data. The model suggests that 31.4% of the data variability could be explained by ultrafine particles (the diameters smaller than or equal to 100 nm). It was difficult to label this factor without chemistry information of the ultrafine particles. However, no gas species were loaded on Factor 1 indicating the ultrafine particles observed in this study were not associated with primary source emissions. The decoupling of the ultrafine particles from the fine particles also implies that the former ones might have been produced and transported to the site by separated mechanisms from those of fine particles. The second factor included the PM 2.5 mass concentration and the number concentrations of particles in the diameter range of 101-400 nm. The loading pattern on Factor 2 led to the conclusion that this factor was contributed by regional transport. The third factor includes CO, NO 2, reactive odd nitrogen (NO y), and SO 2 that were contributed by primary source emissions. The mean wind speed and ozone were loaded in Factor 4 that was labeled as ozone transport. Identification of this factor led to an observation that ozone transport to the site was essentially decoupled from the regional transport factor of fine particles (i.e., Factor 2). Solar radiation was singly included in the fifth factor indicating this is a unique factor. The quality of NO data was marginal and the variable was distilled by the model into Factor 6. A multiple regression analysis further indicated that PM 2.5 mass concentration was best explained by CO, O 3, and number concentrations of particles in the diameter range between 0.1 and 0.4 ?m. We also identified two unique events during the campaign in which the number concentrations of 31-51 nm particles dramatically increased by a factor of 10 in 30 min, reaching 40,000 cm -3 and lasting for a couple of hours. Particles in the size range just below and above those in the 31-51 nm diameter range also exhibited increases during these events, but the changes were much less dramatic.

Cheng, Meng-Dawn; Tanner, Roger L.

109

Aggregates of ultrafine particles modulate lipid peroxidation and bacterial killing by alveolar macrophages  

Microsoft Academic Search

We hypothesized that aggregates of ultrafine carbon and washed diesel particles impair the ability of alveolar macrophages (AM) to kill bacteria and enhance the AM lipid peroxidation (LPO) of lung surfactant.Rat AM were exposed, 5h, to particles 20?g\\/ml. The AM, containing carbon or washed diesel particles, were incubated 2h, with Streptococcus pneumoniae, an American Type Culture Collection (ATCC) strain or

Margot Lundborg; Rabea Bouhafs; Per Gerde; Pär Ewing; Per Camner; Sven-Erik Dahlén; Connie Jarstrand

2007-01-01

110

Synthesis of ultra-fine particles of strontium hexaferrite by a modified co-precipitation method  

Microsoft Academic Search

Uniform size and ultra-fine particles of strontium hexaferrite, SrFe12O19, with a particle size range from 0.1 to 0.2 ?m have been synthesised by what is termed modified co-precipitation from mixed aqueous solutions of iron and strontium nitrates. The results obtained here show that single domain particles of strontium hexaferrite exhibiting a significantly higher coercivity of 444.5 kA\\/m (5.55 kOe) can

A. Ataie; S. Heshmati-Manesh

2001-01-01

111

Synthesis and electrochemistry properties of Sn–Sb ultrafine particles as anode of lithium-ion batteries  

Microsoft Academic Search

Ultrafine particles of Sn–Sb alloys with different chemical composition have been prepared by hydrogen plasma-metal reaction. Structure, morphology, size and chemical composition of the Sn–Sb ultrafine particles were investigated by transmission electron microscopy, X-ray diffraction, BET gas adsorption, and induction-coupled plasma spectroscopy. It was found that all the particles have spherical shapes, with average particle size in the range of

Zhong Wang; Wenhuai Tian; Xingguo Li

2007-01-01

112

SIGNALING MECHANISMS IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES  

EPA Science Inventory

SIGNALING MECHANISMS IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES Y.M. Kim, A.G. Lenz, R. Silbajoris, I. Jaspers and J.M. Samet. Department of Environmental Sciences and Engineering and Center for Environmental Medicine, University of North Carolina, ...

113

CARDIOVASCULAR RESPONSES IN UNRESTRAINED WKY-RATS TO INHALED ULTRAFINE CARBON PARTICLES  

EPA Science Inventory

Abstract This study provides evidence for adverse cardiac effects of inhaled ultrafine particles (UFPs) in healthy WKY rats. Short term exposure (24 h) with carbon UFPs (180 ?g?m ?) induced a moderate but significant heart rate increase of 18 bpm (4.8 %) in association with a ...

114

Bound diffusion of ultrafine particles in a generalized potential: a Mössbauer study  

NASA Astrophysics Data System (ADS)

We have studied the bound diffusion of ferric hydroxide ultrafine particles imbedded in a solvated polymeric network of Dowex 50W - x1,2 cation exchangers. The Mössbauer experimental data were theoretically treated as continuous diffusion in an arbitrary potential. The shape of this potential was reconstructed from the temperature dependence of the Mössbauer lineshape.

Plachinda, A. S.; Sedov, V. E.; Khromov, V. I.; Bashkeev, L. V.; Suzdalev, I. P.

1990-11-01

115

Inertial separation of ultrafine particles by a Laval nozzle type supersonic impactor  

Microsoft Academic Search

Separation of ultrafine particles by inertial effect in a supersonic flow field has been experimentally studied. The experiment was carried out in a Laval nozzle with different configurations. As a result, the cut size was found to decrease as Mach number increases, i.e., gas velocity becomes faster and the smallest cut size by this experiment has an aerodynamic diameter of

Chikao Kanaoka; Jarun Chutmanop; Masayuki Kitada

2001-01-01

116

Regional impacts of ultrafine particle emissions from the surface of the Great Lakes  

Microsoft Academic Search

Quantifying the impacts of aerosols on climate requires a detailed knowledge of both the anthropogenic and the natural contributions to the aerosol population. Recent work has suggested a previously unrecognized natural source of ultrafine particles resulting from breaking waves at the surface of large freshwater lakes. This work is the first modeling study to investigate the potential for this newly

S. H. Chung; B. M. Basarab; T. M. Vanreken

2011-01-01

117

The Rat Ear Vein Model for Investigating In Vivo Thrombogenicity of Ultrafine Particles (UFP)  

Microsoft Academic Search

Recent studies in rodents indicate that intravenous or intra- tracheal administration of ultrafine particles (UFP) increases thrombogenesis in a surgically exposed peripheral vein after photodynamic excitation of intravenously injected rose bengal (RB). We sought to adapt the invasive peripheral vein RB model to a noninvasive monitoring of ear veins under an inverted microscope. Animals received one of the following: an

Vanessa M Silva; Nancy Corson; Alison Elder; Gunter Oberdorster

2005-01-01

118

A land use regression model for ultrafine particles in Vancouver, Canada.  

PubMed

Methods to characterize chronic exposure to ultrafine particles (UFP) can help to clarify potential health effects. Since UFP are not routinely monitored in North America, spatiotemporal models are one potential exposure assessment methodology. Portable condensation particle counters were used to measure particle number concentrations (PNC) to develop a land use regression (LUR) model. PNC, wind speed and direction were measured for sixty minutes at eighty locations during a two-week sampling campaign. We conducted continuous monitoring at four additional locations to assess temporal variation. LUR modeling utilized 135 potential geographic predictors including: road length, vehicle density, restaurant density, population density, land use and others. A novel approach incorporated meteorological data through wind roses as alternates to traditional circular buffers. The range of measured (sixty-minute median) PNC across locations varied seventy-fold (1500-105000 particles/cm(3), mean [SD] = 18200 [15900] particles/cm(3)). Correlations between PNC and concurrently measured two-week average NOX concentrations were 0.6-0.7. A PNC LUR model (R(2) = 0.48, leave-one-out cross validation R(2) = 0.32) including truck route length within 50 m, restaurant density within 200 m, and ln-distance to the port represents the first UFP LUR model in North America. Models incorporating wind roses did not explain more variability in measured PNC. PMID:23550900

Abernethy, Rebecca C; Allen, Ryan W; McKendry, Ian G; Brauer, Michael

2013-05-21

119

Ultrafine particles emitted by flame and electric arc guns for thermal spraying of metals.  

PubMed

The ultrafine aerosol emitted by thermal spraying of metals using flame and electric arc processes has been characterized in terms of particle size distribution and emission rates based on both particle number and mass. Thermal spraying of Zn, Zn/Al, and Al was studied. Measurements taken using an electrical low pressure impactor and a condensation nucleus counter reveal an aerosol made up of very fine particles (80-95% of number distribution <100 nm). Ultrafine particle emission rates produced by the electric arc process are very high, the largest values being recorded during spraying of pure aluminium. This process generates high particle emissions and therefore requires careful consideration and possible rethinking of currently implemented protection measures: ventilated cabins, dust collectors, and personal protective equipment. PMID:20685717

Bémer, Denis; Régnier, Roland; Subra, Isabelle; Sutter, Benjamin; Lecler, Marie T; Morele, Yves

2010-08-01

120

Pulmonary and systemic distribution of inhaled ultrafine silver particles in rats.  

PubMed Central

The cardiovascular system is currently considered a target for particulate matter, especially for ultrafine particles. In addition to autonomic or cytokine mediated effects, the direct interaction of inhaled materials with the target tissue must be examined to understand the underlying mechanisms. In the first approach, pulmonary and systemic distribution of inhaled ultrafine elemental silver (EAg) particles was investigated on the basis of morphology and inductively coupled plasma mass spectrometry (ICP-MS) analysis. Rats were exposed for 6 hr at a concentration of 133 microg EAg m(3) (3 x 10(6) cm(3), 15 nm modal diameter) and were sacrificed on days 0, 1, 4, and 7. ICP-MS analysis showed that 1.7 microg Ag was found in the lungs immediately after the end of exposure. Amounts of Ag in the lungs decreased rapidly with time, and by day 7 only 4% of the initial burden remained. In the blood, significant amounts of Ag were detected on day 0 and thereafter decreased rapidly. In the liver, kidney, spleen, brain, and heart, low concentrations of Ag were observed. Nasal cavities, especially the posterior portion, and lung-associated lymph nodes showed relatively high concentrations of Ag. For comparison, rats received by intratracheal instillation either 150 microL aqueous solution of 7 microg silver nitrate (AgNO(3) (4.4 microg Ag) or 150 microL aqueous suspension of 50 microg agglomerated ultrafine EAg particles. A portion of the agglomerates remained undissolved in the alveolar macrophages and in the septum for at least 7 days. In contrast, rapid clearance of instilled water-soluble AgNO(3) from the lung was observed. These findings show that although instilled agglomerates of ultrafine EAg particles were retained in the lung, Ag was rapidly cleared from the lung after inhalation of ultrafine EAg particles, as well as after instillation of AgNO(3), and entered systemic pathways.

Takenaka, S; Karg, E; Roth, C; Schulz, H; Ziesenis, A; Heinzmann, U; Schramel, P; Heyder, J

2001-01-01

121

Method for the production of ultrafine particles by electrohydrodynamic micromixing  

DOEpatents

The present invention relates to a method for the rapid production of homogeneous, ultrafine inorganic material via liquid-phase reactions. The method of the present invention employs electrohydrodynamic flows in the vicinity of an electrified injector tube placed inside another tube to induce efficient turbulent mixing of two fluids containing reactive species. The rapid micromixing allows liquid-phase reactions to be conducted uniformly at high rates. This approach allows continuous production of non-agglomerated, monopispersed, submicron-sized, sphere-like powders.

DePaoli, David W. (Knoxville, TN); Hu, Zhong Cheng (Knoxville, TN); Tsouris, Constantinos (Oak Ridge, TN)

2001-01-01

122

Coating mechanism of nano-TiO2 films on the surface of ultra-fine calcined coal kaolin particles  

NASA Astrophysics Data System (ADS)

A new type of mineral composite was made by calcined coal kaolin. The interaction mechanism of an inorganic modification reagent TiOSO4 with the surface of ultra-fine calcined coal kaolin particles (substrate) was studied by X-ray photoelectron spectroscopy. The results show that chemisorption exists in the phase boundary between the modification agent and the substrate surface, while physical adsorption occurs on the modification layers of hydrate titanium dioxide. The interaction force was calculated and analyzed according to DLVO theory between ultra-fine calcined coal kaolin particles and hydrate titanium dioxide nano-particles in the modification system. It is shown that the both electrostatic force and van der Waals force are attractive, and the coacervation between ultra-fine calcined coal kaolin particles and hydrate titanium dioxide nano-particles leads to the coating of hydrate titanium dioxide on the surface of ultra-fine calcined coal kaolin particles.

Lin, Hai; Dong, Ying-Bo

2011-08-01

123

Water Condensation Growth Cells for Ultrafine Particle Collection Onto Concentrated Spots  

Microsoft Academic Search

A laminar flow, condensation method, analogous to that employed in the water-based condensation particle counters, is utilized to provide concentrated, low-pressure drop collection of fine and ultrafine particles. With the laminar flow water condensation approach, the aerosol flow is first chilled by a cold walled conditioner, and then introduced into a hot wet-walled condenser. Because water vapor diffuses more rapidly

G. S. Lewis; S. V. Hering; N. Kreisberg

2007-01-01

124

Concentrations of ultrafine, fine and PM 2.5 particles in three European cities  

Microsoft Academic Search

Total number concentrations, number concentrations of ultrafine (0.01–0.1?m) and accumulation (0.1–0.5?m) particles, as well as mass concentration of PM2.5 particles and blackness of PM2.5 filters, which is related to Black Smoke were simultaneously monitored in three European cities during the winter period for three and a half months. The purpose of the study was to describe the differences in concentration

J Ruuskanen; Th Tuch; H Ten Brink; A Peters; A Khlystov; A Mirme; G. P. A Kos; B Brunekreef; H. E Wichmann; G Buzorius; M Vallius; W. G Kreyling; J Pekkanen

2001-01-01

125

Influence of short-term exposure to ultrafine and fine particles on systemic inflammation  

Microsoft Academic Search

Daily to monthly variations in fine particulate matter have been linked to systemic inflammatory responses. It has been hypothesized\\u000a that smaller particles resulting from combustion processes confer higher toxicity. We aim to analyze the association between\\u000a short-term exposure to ultrafine and fine particles and systemic inflammation. We use baseline data (2000–2003) of the Heinz\\u000a Nixdorf Recall Study, a population-based cohort

Sabine HertelAnja; Anja Viehmann; Susanne Moebus; Klaus Mann; Martina Bröcker-Preuss; Stefan Möhlenkamp; Michael Nonnemacher; Raimund Erbel; Hermann Jakobs; Michael Memmesheimer; Karl-Heinz Jöckel; Barbara Hoffmann

2010-01-01

126

Relationships between size segregated mass concentration data and ultrafine particle number concentrations in urban areas  

Microsoft Academic Search

Mass concentration data derived from samples collected with a micro-orifice uniform deposit impactor (MOUDI) in six Australian urban centers during periods of significant particle loading have been used to investigate the relationships between TSP, PM10, PM2.5, PM1 and ultrafine particles. While PM10 and PM2.5 display a clear relationship, the lack of correlation between PM10 and the coarse fraction of PM10

M. D. Keywood; G. P. Ayers; J. L. Gras; R. W. Gillett; D. D. Cohen

1999-01-01

127

Thin glass film between ultrafine conductor particles in thick-film resistors  

Microsoft Academic Search

Thick-film resistors are electrical composites containing ultrafine particles of ruthenate conductor (Pb[sub 2]Ru[sub 2]O[sub 7] in the present materials) distributed in a highly modified silicate glass. The authors show that conductor particles remain flocced in the absence of any applied or capillary pressures, but are separated at equilibrium by a nanometer-thick film of glass. Microstructures show evidence for liquid-phase sintering,

Yet-Ming Chiang; Lee A. Silverman; Roger H. French; Rowland M. Cannon

1994-01-01

128

Energy change of exciton in ultrafine particle due to a dipole at the surface of the particle.  

National Technical Information Service (NTIS)

The Hamiltonian of the exciton in an ultrafine particle (UFP) with a dipole at its surface is given. The exciton energy is calculated as a function of the dielectric constant of the medium outside the UFP and the strength of the dipole. The results show t...

Lai Zuyou Gu Shiwei

1991-01-01

129

ULTRAFINE CARBON PARTICLES INDUCE INTERLEUKIN-8 GENE TRANSCRIPTION AND P38 MAPK ACTIVATION IN NORMAL BRONCHIAL EPITHELIAL CELLS  

EPA Science Inventory

Epidemiological studies suggest that ultrafine particles contribute to particulate matter-induced adverse health effects. Interleukin (IL)-8 is an important proinflammatory cytokine in the human lung that is induced in respiratory cells exposed to a variety of environmental insul...

130

Exposure for ultrafine carbon particles at levels below detectable pulmonary inflammation affects cardiovascular performance in spontaneously hypertensive rats*  

EPA Science Inventory

Rationale: Exposure to particulate matter is a risk factor for cardiopulmonary disease but the related molecular mechanisms are poorly understood. Previously we studied cardiovascular responses in healthy WKY rats following inhalation exposure to ultrafine carbon particles (UfCPs...

131

Characterization of ultrafine particle number concentration and new particle formation in urban environment of Taipei, Taiwan  

NASA Astrophysics Data System (ADS)

An intensive aerosol characterization experiment was performed at the Taipei Aerosol and Radiation Observatory (TARO, 25.02° N, 121.53° E) in the urban area of Taipei, Taiwan during July 2012. Number concentration and size distribution of aerosol particles were measured continuously, which were accompanied by concurrent measurements of mass concentration of submicron particles, PM (d ? 1 ?m), and photolysis rate of ozone, J(O1D). The averaged number concentrations of total (Ntotal), accumulation mode (Nacu), Aitken mode (Ntotal), and nucleation mode (Nnuc) particles were 7.6 × 103 cm-3, 1.2 × 103 cm-3, 4.4 × 103 cm-3, and 1.9 × 103 cm-3, respectively. Accordingly, the ultrafine particles (UFPs, d ? 100 nm) accounted for 83% of the total number concentration of particles measured in this study (10 ? d ? 429 nm), indicating the importance of UFPs to the air quality and radiation budget in Taipei and its surrounding areas. An averaged Nnuc/NOx ratio of ~60 cm-3 ppbv-1 was derived from nighttime measurements, which was suggested to be the characteristic of vehicle emissions that contributed to the "urban background" of nucleation mode particles throughout a day. On the contrary, it was found that the number concentration of nucleation mode particles was independent of NOx and could be elevated up to 10 times the "urban background" levels during daytime, suggesting a substantial amount of nucleation mode particles produced from photochemical processes. Consistency in the time series of the nucleation mode particle concentration and the proxy of H2SO4 production, UVB·SO2, for new particle formation (NPF) events showed that photo-oxidation of SO2 was responsible for the formation of new particles in our study area. Moreover, analysis upon the diameter growth rate, GR, and formation rate of nucleation mode particles, J10-25, found that the values of GR (8.5 ± 6.8 nm h-1) in Taipei were comparable to other urban areas, whereas the values of J10-25 (2.2 ± 1.2 cm-3 s-1) observed in this study were around the low end of the range of new particle formation rate reported by previous investigations. It was revealed that the particle growth rate correlated exponentially with the photolysis of ozone, suggesting the condensable vapors were produced mostly from photo-oxidation reactions. In addition, this study also revealed that both GR and J10-25 exhibited quadratic relationship with the number concentration of particles. The quadratic relationship was inferred as a result of aerosol dynamics and featured NPF process in urban areas.

Cheung, H. C.; Chou, C. C.-K.; Huang, W.-R.; Tsai, C.-Y.

2013-04-01

132

Aerosol-CFD modelling of ultrafine and black carbon particle emission, dilution, and growth near roadways  

NASA Astrophysics Data System (ADS)

Many studies have shown that on-road vehicle emissions are the dominant source of ultrafine particles (UFP; diameter < 100 nm) in urban areas and near-roadway environments. In order to advance our knowledge on the complex interactions and competition among atmospheric dilution, dispersion and dynamics of UFPs, an aerosol dynamics-CFD coupled model is developed and validated against field measurements. A unique approach of applying periodic boundary conditions is proposed to model pollutant dispersion and dynamics in one unified domain from the tailpipe level to the ambient near-road environment. This approach significantly reduces the size of the computational domain, and therefore, allows fast simulation of multiple scenarios. The model is validated against measured turbulent kinetic energy (TKE) and pollution gradients near a major highway. Through a model sensitivity analysis, the relative importance of individual aerosol dynamical processes on the total particle number concentration (N) and particle number-size distribution (PSD) near a highway is investigated. The results demonstrate that (1) coagulation has a negligible effect on N and particle growth, (2) binary homogeneous nucleation (BHN) of H2SO4-H2O is likely responsible for elevated N closest to the road, (3) N and particle growth are very sensitive to the condensation of semi-volatile organics (SVOCs), particle dry deposition, and the interaction between these processes. The results also indicate that, without the proper treatment of atmospheric boundary layer (i.e. its wind profile and turbulence quantities), the nucleation rate would be underestimated by a factor of 5 in the vehicle wake region due to overestimated mixing. Therefore, introducing ABL conditions to activity-based emission models may potentially improve their performance in estimating UFP traffic emissions.

Huang, L.; Gong, S. L.; Gordon, M.; Liggio, J.; Staebler, R. M.; Stroud, C. A.; Lu, G.; Mihele, C.; Brook, J. R.; Jia, C. Q.

2014-05-01

133

Five-year roadside measurements of ultrafine particles in a major Canadian city  

NASA Astrophysics Data System (ADS)

This study reports the diurnal, seasonal and annual variation of ultrafine particles (UFP) in a large city. Particle number (PN) concentrations were measured in Toronto, Canada on a major arterial roadway between March 2006 and May 2011 using a Fast Mobility Particle Sizer. The PN in the size range of 8-300 nm decreased during the measurement period primarily due to changes in the vehicle fleet. PN50 (particles with diameters less than 50 nm) decreased by 21% between 2006 and 2010. Notably, the majority of the reduction occurred during the winter months. PN50 exhibited the strongest seasonality and diurnal trend. PN50-100 (particles between 50 and 100 nm) and PN100-300 (particles between 100 and 300 nm) decreased by 17% and 24%, respectively. Correlation analysis between gas phase criteria pollutants showed good correlation between PN50-100 and NO2, SO2, and PM2.5. In contrast, PN50 exhibited the highest correlation with temperature, NO and NO2. A multiple linear regression model was developed for each size fraction. The model adequately explained the annual, seasonal and day-to-day variability of PN50-100 (R2 = 0.64) and PN100-300 (R2 = 0.83). The model captured the annual and seasonal variability of PN50 but only partially explained the day-to-day variability (R2 = 0.52). The long-term reductions in PN50 indicate that policy interventions are having some success in slowly decreasing UFP concentrations in Toronto.

Sabaliauskas, Kelly; Jeong, Cheol-Heon; Yao, Xiaohong; Jun, Yun-Seok; Jadidian, Parnian; Evans, Greg J.

2012-03-01

134

Ultrafine particle formation in the inland sea breeze airflow in Southwest Europe  

NASA Astrophysics Data System (ADS)

Studies on ultrafine particles (diameter < 100nm) and air quality have mostly focused on vehicle exhaust emissions and on new particle formation in "clean" ambient air. Here we present a study focused on the processes contributing to ultrafine particle concentrations in a city (Huelva, SW Spain) placed close to a coastal area where significant anthropogenic emissions of aerosol precursors occur. The overall data analysis shows that two processes predominantly contribute to the number of particles coarser than 2.5 nm: vehicle exhaust emissions and new particle formation due to photo-chemical activity. As typically occurs in urban areas, vehicle exhaust emissions result in high concentrations of black carbon (BC) and particles coarser than 2.5 nm (N) during the morning rush hours. The highest N concentrations were recorded during the 11:00-17:00 h period, under the sea breeze regime, when low BC concentrations were registered and photochemical activity resulted in high O3 levels and in new particle formation in the aerosol precursors' rich inland airflow. In this period, it is estimated that about 80% of the number of particles are linked to sulfur dioxide emissions. The contributions to N of "carbonaceous material and those compounds nucleating/condensing immediately after emission" and of the "new particle formation processes in air masses rich gaseous precursors (e.g. SO2)" were estimated by means of a relatively novel method based on simultaneous measurements of BC and N. A comparison with two recent studies suggests that the daily cycles of "new particle formation" during the inland sea breeze is blowing period seem to be a feature of ultrafine particles in coastal areas of South-west Europe.

Fernández-Camacho, R.; Rodríguez, S.; de La Rosa, J.; Sánchez de La Campa, A. M.; Viana, M.; Alastuey, A.; Querol, X.

2010-10-01

135

Ultrafine particle formation in the inland sea breeze airflow in Southwest Europe  

NASA Astrophysics Data System (ADS)

Studies on ultrafine particles and air quality have mostly focused on vehicle exhaust emissions and on new particle formation in "clean" ambient air. Here we present a study of the processes contributing to ultrafine particle concentrations in an urban coastal area (Huelva, SW Spain) where significant anthropogenic emissions of aerosol precursors occur. The overall data analysis shows that two processes predominantly contribute to the number of particles coarser than 2.5 nm: vehicle exhaust emissions and new particle formation due to photo-chemical activity. As typically occurs in urban areas, vehicle exhaust emissions result in high concentrations of black carbon (BC) and particles coarser than 2.5 nm (N) during the morning rush hours. The highest N concentrations were recorded during the 11-17 h period, under the sea breeze regime, when photochemical activity resulted in high O3 levels and new particle formation in the aerosol precursors' rich inland airflow. In this period, it is estimated that about 80% of the number of particles are linked to sulfur dioxide emissions. The contributions to N of "carbonaceous material and those compounds nucleating/condensing immediately after emission" and of the "new particle formation processes in air masses rich gaseous precursors (e.g. SO2)" were estimated by means of a relatively novel method based on simultaneous measurements of BC and N. A comparison with two recent studies suggests that the daily cycles of "new particle formation" during the period when the inland sea breeze is blowing period seem to be a feature of ultrafine particles in coastal areas of South-west Europe.

Fernández-Camacho, R.; Rodríguez, S.; de La Rosa, J.; Sánchez de La Campa, A. M.; Viana, M.; Alastuey, A.; Querol, X.

2010-07-01

136

Ultrafine particle deposition and clearance in the healthy and obstructed lung.  

PubMed

Numerous epidemiologic studies have shown associations between exposure to particulate air pollution and acute increases in morbidity and mortality, particularly in persons with chronic obstructive pulmonary disease. The dosimetry of ultrafine particles in the human lung is poorly characterized. We studied the deposition and clearance of an ultrafine technetium-99m-labeled aerosol in 10 patients with chronic obstructive pulmonary disease and in 9 healthy subjects. Particle retention was followed for 2 hours after inhalation and again at 24 hours by gamma scintigraphy. Central-to-peripheral ratios indexed airway deposition. Particle accumulation in the liver was examined by quantifying activity below the right lung. The dose rate for an aerosol exposure of 10 micro g/m(3) was calculated. Patients had a significantly greater dose rate than healthy subjects (2.9 +/- 1.0 versus 1.9 +/- 0.4 micro g/h, p = 0.02). Central-to-peripheral ratios were slightly greater in patients than in healthy subjects (1.11 +/- 0.10 versus 1.01 +/- 0.11, p = 0.05). Clearance did not statistically differ between health and disease. On average, 24-hour retention was 85 +/- 8% (corrected for isotope dissolution). No accumulation in the liver's vicinity was observed. Data suggest that relative to healthy subjects, patients with moderate-to-severe airways obstruction receive an increased dose from ultrafine particle exposure. PMID:12403694

Brown, James S; Zeman, Kirby L; Bennett, William D

2002-11-01

137

Increased asthma medication use in association with ambient fine and ultrafine particles  

Microsoft Academic Search

ABSTRACT: The association between particulate air pollution and asthma,medication use and symptoms was assessed in a panel study of 53 adult asthmatics in Erfurt, Germany,in winter 1996\\/1997. Number concentrations of ultrafine particles, 0.01?0.1 mm in diameter (NC0.01?0.1), mean 17,300?cm,GSF - National Research Center for Environment,and Health, Institute of Inhalation Biology, Neuherberg, Germany. Correspondence: S. von Klot, GSF -

S. von Klot; G. Wolke; T. Tuch; J. Heinrich; D. W. Dockery; J. Schwartz; W. G. Kreylingz; H. E. Wichmann; A. Peters

2002-01-01

138

Ultrafine surface machining of glass using laser-produced charged particles  

Microsoft Academic Search

Ultra-fine machining of glass substrates using charged particles from laser-produced metal plasma is reported. Since the metal target exhibits high efficiency of linear absorption of nanosecond 532nm laser irradiation, the threshold fluence for machining the glass substrate is lower than 1.2J\\/cm2. Pulse energy of 5–8?J\\/pulse is adequate for this high-precision surface machining process. The optimal parameters for the superior quality

Chengde Li; Suwas Nikumb

2003-01-01

139

Ultrafine microsphere particles of zirconium titanate produced by homogeneous dielectric-tuning coprecipitation  

Microsoft Academic Search

Zirconium titanates are widely used in electrical (common microwave dielectrics) and optical devices as well as in bifunctional catalysis and structural ceramics. In this paper, ultrafine amorphous solid microsphere precursor particles of zirconium titanate (ZrxTi1 - xO2) with possibly tailored intraparticle nanostructure (i.e., nanosized pores) were synthesized by a “dielectric-tuning” solution coprecipitation method, in which inorganic salts were dissolved in

Michael Z.-C. Hu; E. A. Payzant; K. R. Booth; C. J. Rawn; R. D. Hunt; L. F. Allard

2003-01-01

140

Assessment of atmospheric ultrafine carbon particle-induced human health risk based on surface area dosimetry  

Microsoft Academic Search

Evidence shows a strong correlation between human mortality\\/morbidity and atmospheric ultrafine carbon particle (UFCP with aerodynamic diameter <18nm). Theoretical and experimental studies have attempted to use mass concentration\\/dose as exposure dosimetry to construct the dose-response relationships. Yet little attention has been given to the problem of using surface area dosimetry in UFCP-related risk assessment. We introduced an integrated risk assessment

Chia-Pin Chio; Chung-Min Liao

2008-01-01

141

Pulmonary Responses of Mice, Rats, and Hamsters to Subchronic Inhalation of Ultrafine Titanium Dioxide Particles  

Microsoft Academic Search

A multispecies, subchronic, inhalation study comparing pulmo- nary responses to ultrafine titanium dioxide (uf-TiO2) was per- formed. Female rats, mice, and hamsters were exposed to aerosol concentrations of 0.5, 2.0, or 10 mg\\/m 3 uf-TiO2 particles for 6 h\\/day, 5 days\\/week, for 13 weeks. Following the exposure period, animals were held for recovery periods of 4, 13, 26, or 52

Edilberto Bermudez; James B. Mangum; Brian A. Wong; Bahman Asgharian; Paul M. Hext; David B. Warheit; Jeffrey I. Everitt

2004-01-01

142

Exposure to ultrafine particles and PM 2.5 in four Sydney transport modes  

Microsoft Academic Search

Concentrations of ultrafine (<0.1 ?m) particles (UFPs) and PM2.5 (<2.5 ?m) were measured whilst commuting along a similar route by train, bus, ferry and automobile in Sydney, Australia. One trip on each transport mode was undertaken during both morning and evening peak hours throughout a working week, for a total of 40 trips. Analyses comprised one-way ANOVA to compare overall (i.e. all

Luke D. Knibbs; Richard J. de Dear

2010-01-01

143

Linking In-Vehicle Ultrafine Particle Exposures to On-Road Concentrations  

PubMed Central

For traffic-related pollutants like ultrafine particles (UFP, Dp < 100 nm), a significant fraction of overall exposure occurs within or close to the transit microenvironment. Therefore, understanding exposure to these pollutants in such microenvironments is crucial to accurately assessing overall UFP exposure. The aim of this study was to develop models for predicting in-cabin UFP concentrations if roadway concentrations are known, taking into account vehicle characteristics, ventilation settings, driving conditions and air exchange rates (AER). Particle concentrations and AER were measured in 43 and 73 vehicles, respectively, under various ventilation settings and driving speeds. Multiple linear regression (MLR) and generalized estimating equation (GEE) regression models were used to identify and quantify the factors that determine inside-to-outside (I/O) UFP ratios and AERs across a full range of vehicle types and ages. AER was the most significant determinant of UFP I/O ratios, and was strongly influenced by ventilation setting (recirculation or outside air intake). Inclusion of ventilation fan speed, vehicle age or mileage, and driving speed explained greater than 79% of the variability in measured UFP I/O ratios.

Hudda, Neelakshi; Eckel, Sandrah P.; Knibbs, Luke D.; Sioutas, Constantinos; Delfino, Ralph J.; Fruin, Scott A.

2013-01-01

144

Linking in-vehicle ultrafine particle exposures to on-road concentrations  

NASA Astrophysics Data System (ADS)

For traffic-related pollutants like ultrafine particles (UFP), a significant fraction of overall exposure occurs within or close to the transit microenvironment. Therefore, understanding exposure to these pollutants in such microenvironments is crucial to accurately assessing overall UFP exposure. The aim of this study was to develop models for predicting in-cabin UFP concentrations if roadway concentrations are known, quantifying the effect of vehicle characteristics, ventilation settings, driving conditions and air exchange rates (AER). Particle concentrations and AER were measured in 43 and 73 vehicles, respectively, under various ventilation settings and driving speeds. Multiple linear regression (MLR) and generalized estimating equation (GEE) regression models were used to identify and quantify the factors that determine inside-to-outside (I/O) UFP ratios and AERs across a full range of vehicle types and ages. AER was the most significant determinant of UFP I/O ratios, and was most strongly influenced by ventilation setting (recirculation or outside air intake). Further inclusion of ventilation fan speed, vehicle age or mileage, and driving speed explained greater than 79% of the variability in measured UFP I/O ratios.

Hudda, Neelakshi; Eckel, Sandrah P.; Knibbs, Luke D.; Sioutas, Constantinos; Delfino, Ralph J.; Fruin, Scott A.

2012-11-01

145

The mapping of fine and ultrafine particle concentrations in an engine machining and assembly facility.  

PubMed

Aerosol mapping was used to assess particle number and mass concentration in an engine machining and assembly facility in the winter and spring. Number and mass concentration maps were constructed from data collected with two mobile sampling carts, each equipped with a condensation particle counter (10 nm < diameter < 1 microm) and an optical particle counter (300 nm < diameter < 20 microm). Number concentrations inside the facility ranged from 15 to 150 times greater than that outside the facility and were highly dependent on season. The greatest number concentration (>1,000,000 particles cm(-3)) occurred in winter in an area where mass concentration was low (<0.10 mg m(-3)). The increased number of particles was attributed to the exhaust of direct-fire, natural-gas burners used to heat the supply air. The greatest mass concentrations were found around metalworking operations that were poorly enclosed. The larger particles that dominated particle mass in this area were accompanied by ultrafine particles, probably generated through evaporation and subsequent condensation of metalworking fluid components. Repeat mapping events demonstrated that these ultrafine particles persist in workplace air over long time periods. PMID:16361396

Peters, Thomas M; Heitbrink, William A; Evans, Douglas E; Slavin, Thomas J; Maynard, Andrew D

2006-04-01

146

Ultrafine particle size distribution during high velocity impact of high density metals  

NASA Astrophysics Data System (ADS)

In the event of high-energy penetrator impact, people involved in battlefield scenarios are exposed to the additional hazard stemming from ultrafine metallic particles, i.e. exposure, inhalation, and respiration of aerolized metals. In order to have reliable quantitative measurement of the aerosol particles generated under controlled impact conditions, an experimental set-up was designed to perform impact tests with light gas-gun in chamber. During the impact events, aerosol particle size distributions and total concentrations were measured with a one-second time resolution. In this study preliminary results relative to high purity copper projectile impact at different velocities are presented.

Buonanno, Giorgio; Stabile, Luca; Ruggiero, Andrew; Iannitti, Gianluca; Bonora, Nicola

2012-03-01

147

Predominance of soot-mode ultrafine particles in Santiago de Chile: Possible sources  

NASA Astrophysics Data System (ADS)

A monitoring campaign was performed in Santiago de Chile during a winter month of 2003 and 2006 (July) using several instruments to measure the size distribution of particulate material. For the first time, the size distribution of ultrafine particles was measured in Santiago, and an estimation of its sources was done by analyzing its temporal variation. The study was performed in three sites; one of them is located in the eastern part of Santiago, a sector with low particle concentration and about 100 m from a busy street. The other site is located in the western part, which is the sector that has the highest concentration of fine and coarse particle matter during winter, also located far from a street. The third site is located within 5 m from the busiest street in Santiago. In all stations traffic is the dominating source for fine and ultrafine particles and the size distribution is peaked towards 60-100 nm (soot mode). Only in the site near the street, it is possible to see a clear peak towards smaller sizes (10-30 nm). The size distribution measurements presented here indicate that aerosol dynamics play a more important role for the Santiago case as compared to cleaner cities in Europe. Changes in the particle size during different hours of the day reflect both variations in meteorological mixing conditions as well as effects of aerosol dynamic processes such as coagulation, condensation and dry deposition. A relative increase in the number of the larger ultrafine particles ( d ? 70 nm), as compared to the number of smaller particles ( d < 70 nm) correlated with wind speed is an indication of pollution transport with aged particles from other parts of the city.

Gramsch, Ernesto; Gidhagen, Lars; Wahlin, Peter; Oyola, Pedro; Moreno, Francisco

148

Deposition of inhaled charged ultrafine particles in a simple tracheal model  

SciTech Connect

The deposition of ultrafine (d [le] 200 nm) particles on airway surfaces is an important determinant of the radiation dose that results from inhalation of radon progeny. The activity median diameter of particles to which radon daughters attach is small (10--140 nm). In the absence of charge, deposition in the upper airways of the respiratory system occurs by impaction for large particles and diffusion for small particles. Sedimentation is negligible due to the high flow rates in these airways. Experiments conducted in hollow casts and in vivo in humans have all shown an increase in deposition due to the particle charge. In vivo experimental results showed that there exists a threshold value of charge on the particle (q[sub c]) above which the electrostatic charge enhances deposition. These experiments were performed for particles for which deposition by diffusion is small (d [le] 300 nm). Deposition of ultrafine particles in the airways may occur by a combined mechanism of diffusion and electrostatic charge.

Cohen, B.S.; Ayres, L.; Xiong, J.

1992-01-01

149

Deposition of inhaled charged ultrafine particles in a simple tracheal model  

SciTech Connect

The deposition of ultrafine (d {le} 200 nm) particles on airway surfaces is an important determinant of the radiation dose that results from inhalation of radon progeny. The activity median diameter of particles to which radon daughters attach is small (10--140 nm). In the absence of charge, deposition in the upper airways of the respiratory system occurs by impaction for large particles and diffusion for small particles. Sedimentation is negligible due to the high flow rates in these airways. Experiments conducted in hollow casts and in vivo in humans have all shown an increase in deposition due to the particle charge. In vivo experimental results showed that there exists a threshold value of charge on the particle (q{sub c}) above which the electrostatic charge enhances deposition. These experiments were performed for particles for which deposition by diffusion is small (d {le} 300 nm). Deposition of ultrafine particles in the airways may occur by a combined mechanism of diffusion and electrostatic charge.

Cohen, B.S.; Ayres, L.; Xiong, J.

1992-11-01

150

Exposure Assessment for Atmospheric Ultrafine Particles (UFPs) and Implications in Epidemiologic Research  

PubMed Central

Epidemiologic research has shown increases in adverse cardiovascular and respiratory outcomes in relation to mass concentrations of particulate matter (PM) ?2.5 or ?10 ?m in diameter (PM2.5, PM10, respectively). In a companion article [Delfino RJ, Sioutas C, Malik S. 2005. Environ Health Perspect 113(8):934–946]), we discuss epidemiologic evidence pointing to underlying components linked to fossil fuel combustion. The causal components driving the PM associations remain to be identified, but emerging evidence on particle size and chemistry has led to some clues. There is sufficient reason to believe that ultrafine particles < 0.1 ?m (UFPs) are important because when compared with larger particles, they have order of magnitudes higher particle number concentration and surface area, and larger concentrations of adsorbed or condensed toxic air pollutants (oxidant gases, organic compounds, transition metals) per unit mass. This is supported by evidence of significantly higher in vitro redox activity by UFPs than by larger PM. Although epidemiologic research is needed, exposure assessment issues for UFPs are complex and need to be considered before undertaking investigations of UFP health effects. These issues include high spatial variability, indoor sources, variable infiltration of UFPs from a variety of outside sources, and meteorologic factors leading to high seasonal variability in concentration and composition, including volatility. To address these issues, investigators need to develop as well as validate the analytic technologies required to characterize the physical/chemical nature of UFPs in various environments. In the present review, we provide a detailed discussion of key characteristics of UFPs, their sources and formation mechanisms, and methodologic approaches to assessing population exposures.

Sioutas, Constantinos; Delfino, Ralph J.; Singh, Manisha

2005-01-01

151

Potential role of ultrafine particles in associations between airborne particle mass and cardiovascular health.  

PubMed

Numerous epidemiologic time-series studies have shown generally consistent associations of cardiovascular hospital admissions and mortality with outdoor air pollution, particularly mass concentrations of particulate matter (PM) < or = 2.5 or < or = 10 microm in diameter (PM2.5, PM10). Panel studies with repeated measures have supported the time-series results showing associations between PM and risk of cardiac ischemia and arrhythmias, increased blood pressure, decreased heart rate variability, and increased circulating markers of inflammation and thrombosis. The causal components driving the PM associations remain to be identified. Epidemiologic data using pollutant gases and particle characteristics such as particle number concentration and elemental carbon have provided indirect evidence that products of fossil fuel combustion are important. Ultrafine particles < 0.1 microm (UFPs) dominate particle number concentrations and surface area and are therefore capable of carrying large concentrations of adsorbed or condensed toxic air pollutants. It is likely that redox-active components in UFPs from fossil fuel combustion reach cardiovascular target sites. High UFP exposures may lead to systemic inflammation through oxidative stress responses to reactive oxygen species and thereby promote the progression of atherosclerosis and precipitate acute cardiovascular responses ranging from increased blood pressure to myocardial infarction. The next steps in epidemiologic research are to identify more clearly the putative PM casual components and size fractions linked to their sources. To advance this, we discuss in a companion article (Sioutas C, Delfino RJ, Singh M. 2005. Environ Health Perspect 113:947-955) the need for and methods of UFP exposure assessment. PMID:16079061

Delfino, Ralph J; Sioutas, Constantinos; Malik, Shaista

2005-08-01

152

Potential Role of Ultrafine Particles in Associations between Airborne Particle Mass and Cardiovascular Health  

PubMed Central

Numerous epidemiologic time-series studies have shown generally consistent associations of cardiovascular hospital admissions and mortality with outdoor air pollution, particularly mass concentrations of particulate matter (PM) ?2.5 or ?10 ?m in diameter (PM2.5, PM10). Panel studies with repeated measures have supported the time-series results showing associations between PM and risk of cardiac ischemia and arrhythmias, increased blood pressure, decreased heart rate variability, and increased circulating markers of inflammation and thrombosis. The causal components driving the PM associations remain to be identified. Epidemiologic data using pollutant gases and particle characteristics such as particle number concentration and elemental carbon have provided indirect evidence that products of fossil fuel combustion are important. Ultrafine particles < 0.1 ?m (UFPs) dominate particle number concentrations and surface area and are therefore capable of carrying large concentrations of adsorbed or condensed toxic air pollutants. It is likely that redox-active components in UFPs from fossil fuel combustion reach cardiovascular target sites. High UFP exposures may lead to systemic inflammation through oxidative stress responses to reactive oxygen species and thereby promote the progression of atherosclerosis and precipitate acute cardiovascular responses ranging from increased blood pressure to myocardial infarction. The next steps in epidemiologic research are to identify more clearly the putative PM casual components and size fractions linked to their sources. To advance this, we discuss in a companion article (Sioutas C, Delfino RJ, Singh M. 2005. Environ Health Perspect 113:947–955) the need for and methods of UFP exposure assessment.

Delfino, Ralph J.; Sioutas, Constantinos; Malik, Shaista

2005-01-01

153

Combustion-Derived Ultrafine Particles Transport Organic Toxicants to Target Respiratory Cells  

PubMed Central

Epidemiologic evidence supports associations between inhalation of fine and ultrafine ambient particulate matter [aerodynamic diameter ? 2.5 ?m (PM2.5)] and increases in cardiovascular/respiratory morbidity and mortality. Less attention has been paid to how the physical and chemical characteristics of these particles may influence their interactions with target cells. Butadiene soot (BDS), produced during combustion of the high-volume petrochemical 1,3-butadiene, is rich in polynuclear aromatic hydrocarbons (PAHs), including known carcinogens. We conducted experiments to characterize BDS with respect to particle size distribution, assembly, PAH composition, elemental content, and interaction with respiratory epithelial cells. Freshly generated, intact BDS is primarily (> 90%) PAH-rich, metals-poor (nickel, chromium, and vanadium concentrations all < 1 ppm) PM2.5, composed of uniformly sized, solid spheres (30–50 nm) in aggregated form. Cells of a human bronchial epithelial cell line (BEAS-2B) exhibit sequential fluorescent responses—a relatively rapid (~ 30 min), bright but diffuse fluorescence followed by the slower (2–4 hr) appearance of punctate cytoplasmic fluorescence—after BDS is added to medium overlying the cells. The fluorescence is associated with PAH localization in the cells. The ultrafine BDS particles move down through the medium to the cell membrane. Fluorescent PAHs are transferred from the particle surface to the cell membrane, cross the membrane into the cytosol, and appear to accumulate in lipid vesicles. There is no evidence that BDS particles pass into the cells. The results demonstrate that uptake of airborne ultrafine particles by target cells is not necessary for transfer of toxicants from the particles to the cells.

Penn, Arthur; Murphy, Gleeson; Barker, Steven; Henk, William; Penn, Lynn

2005-01-01

154

Combustion-derived ultrafine particles transport organic toxicants to target respiratory cells.  

PubMed

Epidemiologic evidence supports associations between inhalation of fine and ultrafine ambient particulate matter [aerodynamic diameter < or = 2.5 microm (PM2.5)] and increases in cardiovascular/respiratory morbidity and mortality. Less attention has been paid to how the physical and chemical characteristics of these particles may influence their interactions with target cells. Butadiene soot (BDS), produced during combustion of the high-volume petrochemical 1,3-butadiene, is rich in polynuclear aromatic hydrocarbons (PAHs), including known carcinogens. We conducted experiments to characterize BDS with respect to particle size distribution, assembly, PAH composition, elemental content, and interaction with respiratory epithelial cells. Freshly generated, intact BDS is primarily (> 90%) PAH-rich, metals-poor (nickel, chromium, and vanadium concentrations all < 1 ppm) PM2.5, composed of uniformly sized, solid spheres (30-50 nm) in aggregated form. Cells of a human bronchial epithelial cell line (BEAS-2B) exhibit sequential fluorescent responses--a relatively rapid (approximately 30 min), bright but diffuse fluorescence followed by the slower (2-4 hr) appearance of punctate cytoplasmic fluorescence--after BDS is added to medium overlying the cells. The fluorescence is associated with PAH localization in the cells. The ultrafine BDS particles move down through the medium to the cell membrane. Fluorescent PAHs are transferred from the particle surface to the cell membrane, cross the membrane into the cytosol, and appear to accumulate in lipid vesicles. There is no evidence that BDS particles pass into the cells. The results demonstrate that uptake of airborne ultrafine particles by target cells is not necessary for transfer of toxicants from the particles to the cells. PMID:16079063

Penn, Arthur; Murphy, Gleeson; Barker, Steven; Henk, William; Penn, Lynn

2005-08-01

155

Ultrafine particle size distributions measured in aircraft exhaust plumes  

Microsoft Academic Search

Fast-response measurements of particle size distributions were made for the first time in the near-field plume of a Boeing 737-300 aircraft burning fuel with fuel sulfur (S) contents (FSCs) of 56 and 2.6 ppmm, as well as in fresh and dissipating contrails from the same aircraft, using nine particle counters operating in parallel. Nonsoot particles were present in high concentrations,

Charles A. Brock; Franz Schröder; Bernd Kärcher; Andreas Petzold; Reinhold Busen; Markus Fiebig

2000-01-01

156

Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions  

SciTech Connect

The program objective is to generate ultra-fine catalyst particles (20 to 400 {Angstrom} in size) and quantify their potential for improving coal dissolution in the solubilization stage of two-stage catalytic-catalytic liquefaction systems. It has been shown that catalyst activity increases significantly with decreasing particle size for particle sizes in the submicron range. Ultra-fine catalyst particle generation will be accomplished using a novel two-step process. First, the severe conditions produced by a supercritical fluid (e.g., supercritical H{sub 2}O or CO{sub 2}) will be used to dissolve suitable catalyst compounds (e.g., Fe{sub 2}O{sub 3}, FeS{sub 2}, and/or Fe(CO){sub 5}). Sulfur containing compounds may be added to the supercritical solvent during catalyst dissolution to enhance the catalytic activity of the resulting ultra-fine, iron based, catalyst particles.

Not Available

1991-08-01

157

Ultrafine particle deposition to vegetation branches: wind tunnel investigation of the effect of canopy medium and particle size and charge  

NASA Astrophysics Data System (ADS)

Ultrafine particles (UFP) have attracted much attention in recent years due to their influence on atmospheric concentrations of cloud condensation nuclei (CCN) and the consequent effect on cloud albedo and global climate. To understand UFP lifetime in the atmosphere, both sources and sinks need to be known. One important sink for UFP is removal by vegetation. The main collection mechanism by vegetation is Brownian diffusion with a possible contribution of electrostatic forces. Here we report measurements of collection efficiency of UFP by pine and juniper branches in a wind tunnel at different wind speeds, branch orientations, and packing densities. The effect of particle charge is also investigated. Two modeling approached have been developed to describe UFP deposition to vegetation branches. One treats vegetation as a fibrous filter with a characteristic fiber size; the other treats it as a random porous medium. The experiments agreed well with predictions from both models within 20%. Upon bridging these two modeling approaches, estimates of the effective fiber diameter can now be derived from conventional canopy attributes, such as the leaf area index. These results can benefit future air quality and climate models incorporating UFP.

Khlystov, A.; Lin, M.; Katul, G. G.

2012-12-01

158

A review of commuter exposure to ultrafine particles and its health effects  

NASA Astrophysics Data System (ADS)

Ultrafine particles (UFPs, <100 nm) are produced in large quantities by vehicular combustion and are implicated in causing several adverse human health effects. Recent work has suggested that a large proportion of daily UFP exposure may occur during commuting. However, the determinants, variability and transport mode-dependence of such exposure are not well-understood. The aim of this review was to address these knowledge gaps by distilling the results of 'in-transit' UFP exposure studies performed to-date, including studies of health effects. We identified 47 exposure studies performed across 6 transport modes: automobile, bicycle, bus, ferry, rail and walking. These encompassed approximately 3000 individual trips where UFP concentrations were measured. After weighting mean UFP concentrations by the number of trips in which they were collected, we found overall mean UFP concentrations of 3.4, 4.2, 4.5, 4.7, 4.9 and 5.7 × 10 4 particles cm -3 for the bicycle, bus, automobile, rail, walking and ferry modes, respectively. The mean concentration inside automobiles travelling through tunnels was 3.0 × 10 5 particles cm -3. While the mean concentrations were indicative of general trends, we found that the determinants of exposure (meteorology, traffic parameters, route, fuel type, exhaust treatment technologies, cabin ventilation, filtration, deposition, UFP penetration) exhibited marked variability and mode-dependence, such that it is not necessarily appropriate to rank modes in order of exposure without detailed consideration of these factors. Ten in-transit health effects studies have been conducted and their results indicate that UFP exposure during commuting can elicit acute effects in both healthy and health-compromised individuals. We suggest that future work should focus on further defining the contribution of in-transit UFP exposure to total UFP exposure, exploring its specific health effects and investigating exposures in the developing world.

Knibbs, Luke D.; Cole-Hunter, Tom; Morawska, Lidia

2011-05-01

159

MEMS-based silicon cantilevers with integrated electrothermal heaters for airborne ultrafine particle sensing  

NASA Astrophysics Data System (ADS)

The development of low-cost and low-power MEMS-based cantilever sensors for possible application in hand-held airborne ultrafine particle monitors is described in this work. The proposed resonant sensors are realized by silicon bulk micromachining technology with electrothermal excitation, piezoresistive frequency readout, and electrostatic particle collection elements integrated and constructed in the same sensor fabrication process step of boron diffusion. Built-in heating resistor and full Wheatstone bridge are set close to the cantilever clamp end for effective excitation and sensing, respectively, of beam deflection. Meanwhile, the particle collection electrode is located at the cantilever free end. A 300 ?m-thick, phosphorus-doped silicon bulk wafer is used instead of silicon-on-insulator (SOI) as the starting material for the sensors to reduce the fabrication costs. To etch and release the cantilevers from the substrate, inductively coupled plasma (ICP) cryogenic dry etching is utilized. By controlling the etching parameters (e.g., temperature, oxygen content, and duration), cantilever structures with thicknesses down to 10 - 20 ?m are yielded. In the sensor characterization, the heating resistor is heated and generating thermal waves which induce thermal expansion and further cause mechanical bending strain in the out-of-plane direction. A resonant frequency of 114.08 +/- 0.04 kHz and a quality factor of 1302 +/- 267 are measured in air for a fabricated rectangular cantilever (500x100x13.5 ?m3). Owing to its low power consumption of a few milliwatts, this electrothermal cantilever is suitable for replacing the current external piezoelectric stack actuator in the next generation of the miniaturized cantilever-based nanoparticle detector (CANTOR).

Wasisto, Hutomo Suryo; Merzsch, Stephan; Waag, Andreas; Peiner, Erwin

2013-05-01

160

Development of the electroacoustic dewatering (EAD) process for fine/ultrafine coal. Eighth quarterly progress report.  

National Technical Information Service (NTIS)

Battelle is undertaking engineering development of an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acou...

B. C. Kim C. L. Criner H. Wu R. Menton N. Senapati

1990-01-01

161

Removal of fine and ultrafine particles from indoor air environments by the unipolar ion emission  

NASA Astrophysics Data System (ADS)

The continuous emission of unipolar ions was evaluated in order to determine its ability to remove fine and ultrafine particles from indoor air environments. The evolution of the indoor aerosol concentration and particle size distribution was measured in real time with the ELPI in a room-size (24.3 m 3) test chamber where the ion emitter was operating. After the results were compared with the natural decay, the air cleaning factor was determined. The particle aerodynamic size range of ˜0.04-2 ?m was targeted because it represents many bioaerosol agents that cause emerging diseases, as well as those that can be used for biological warfare or in the event of bioterrorism. The particle electric charge distribution (also measured in the test chamber with the ELPI) was rapidly affected by the ion emission. It was concluded that the corona discharge ion emitters (either positive or negative), which are capable of creating an ion density of 10 5-10 6 e ± cm -3, can be efficient in controlling fine and ultrafine aerosol pollutants in indoor air environments, such as a typical office or residential room. At a high ion emission rate, the particle mobility becomes sufficient so that the particle migration results in their deposition on the walls and other indoor surfaces. Within the tested ranges of the particle size and ion density, the particles were charged primarily due to the diffusion charging mechanism. The particle removal efficiency was not significantly affected by the particle size, while it increased with increasing ion emission rate and the time of emission. The performance characteristics of three commercially available ionic air purifiers, which produce unipolar ions by corona discharge at relatively high emission rates, were evaluated. A 30-minute operation of the most powerful device among those tested resulted in the removal of about 97% of 0.1 ?m particles and about 95% of 1 ?m particles from the air in addition to the natural decay effect.

Uk Lee, Byung; Yermakov, Mikhail; Grinshpun, Sergey A.

162

Using the Generalised Additive Model to model the particle number count of ultrafine particles  

NASA Astrophysics Data System (ADS)

In this paper, we compare the Generalised Linear Model (GLM) and Generalised Additive Model (GAM) for modelling the particle number concentration (PNC) of outdoor, airborne ultrafine particles in Helsinki, Finland. We examine temporal trends in PNC and examine the relationship between PNC and rainfall, wind speed and direction, humidity, temperature and solar insolation. Model choice is via the Akaike Information Criterion (AIC). We have shown that the Generalised Additive Model provides a better fit than the equivalent Generalised Linear Model (ELM) when fitting models with the same covariates with equivalent degrees of freedom (AIC and BIC for the GAM are 10266.52 and 10793.04, AIC and BIC for the ELM are 10297.19 and 10885.97, both have an R2 value of 0.836). We also present results that show that modelling both temporal trends and the effect of rainfall, wind speed and direction, humidity, temperature and solar insolation yields a better fitting model, according to the AIC, than either temporal trends or meteorological conditions by themselves. The model is applicable to any longitudinal monitoring-type measurement campaign where long time series are recorded. Use of this technique may be inappropriate for very short measurement campaigns. Attempting to fit a representative daily trend to one or two days' measurements may lead to a high degree of uncertainty; inclusion of a yearly trend requires having at least a year's worth of data with few gaps, particularly large gaps. In such a situation, the temporal trends may end up being penalised to zero and the model reverts to one largely influenced by meteorology.

Clifford, S.; Low Choy, S.; Hussein, T.; Mengersen, K.; Morawska, L.

2011-10-01

163

Atmospheric Condensational Properties of Ultrafine Chain and Fractal Aerosol Particles  

NASA Technical Reports Server (NTRS)

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

Marlow, William H.

1997-01-01

164

ULTRAFINE PARTICLE DISPOSITION IN THE HEALTHY AND MILDLY OBSTRUCTED LUNG  

EPA Science Inventory

ABSTRACT We have shown previously that EGF receptor signaling is triggered by metals associated with ambient air particles. Specifically, we demonstrated that As, Zn and V activated the EGF receptor tyrosine kinase and the downstream kinases, MEK1/2 and ERK1/2. In this study, ...

165

The role of free radicals in the toxic and inflammatory effects of four different ultrafine particle types.  

PubMed

PM10 contains an ultrafine component, which is generally derived from combustion processes. This ultrafine fraction may be a factor in the increases in exacerbations of respiratory disease and deaths from cardiorespiratory causes associated with transient increases in levels of PM10. By using four different ultrafine particles (carbon black, cobalt, nickel, and titanium dioxide), we set out to determine the attributes of the ultrafine particle (surface area, chemical composition, particle number, or surface reactivity) that contribute most to its toxicity and proinflammatory effects both in vivo and in vitro. Instillation of 125 micro g ultrafine carbon black (UFCB) and ultrafine cobalt (UFCo) particles induced a significant influx of neutrophils at both 4 and 18 h postinstillation. Accompanying the influx of neutrophils was an increase in macrophage inflammatory protein-2 (MIP-2) (at 4 h) and an increase in gamma-glutamyl transpeptidase (at 18 h) in bronchoalveolar lavage fluid (BAL). Ultrafine nickel (UFNi) did not induce a significant increase in neutrophil influx until 18 h postinstillation. The increase in neutrophils induced by UFNi at this timepoint was comparable to that induced by UFCo and UFCB. UFTi did not induce a significant increase in neutrophils following instillation into the rat lung. The levels of MIP-2 observed at 4 h and neutrophil influx at 18 h induced by the particle samples were consistent with the pattern of surface free radical generation (as measured by the plasmid scission assay) whereby UFCo, UFCB, and UFNi all cause significant increases in inflammatory markers, as well as inducing a significant depletion of supercoiled plasmid DNA, indicative of hydroxyl radical generation. A role for free radicals and reactive oxygen species (ROS) in mediating ultrafine inflammation is further strengthened by the ability of the antioxidants N-acetylcysteine (NAC) and glutathione monoethyl ester (GSHme) to block the particle induced release of tumour necrosis factor-alpha (TNF-alpha) from alveolar macrophages in vitro. The ultrafine particles in PM10 may cause adverse effects via oxidative stress, and this could have implications for susceptible individuals. Susceptible individuals, such as those with COPD or asthma, already exhibit preexisting oxidative stress and hence are in a primed state for further oxidative stress induced by occupational or environmental particles. PMID:12476359

Dick, Colin A J; Brown, David M; Donaldson, Ken; Stone, Vicki

2003-01-01

166

Nanocrystallization and phase transformation in monodispersed ultrafine zirconia particles from various homogeneous precipitation methods  

SciTech Connect

Monodispersed ultrafine (nano- to micrometer) zirconia precursor powders were synthesized by three different physicochemical methods: (1) forced hydrolysis, (2) homogeneous precipitation in inorganic salt solutions, and (3) hydrolysis/condensation of alkoxide. The forced hydrolysis method produced monoclinic nanocrystalline particles (cube shaped) of nanometer scale, which depended largely on the initial salt concentration. Methods 2 and 3, both involving the use of alcohol as a solvent, exhibited a faster particle formation rate and generated amorphous ultrafine (submicrometer) monodispersed microspheres, indicating that the presence of alcohol may have stimulated particle nucleation due to its low dielectric property (and, thus, the low solubility of nucleus species in mixed water-alcohol solutions). Nucleation and growth of the particles in solutions are discussed based on the measurements obtained by small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS). High-temperature X-ray diffraction (HTXRD) and TGA/DTA studies elucidated the differences in phase transformation for different types of powders. The most interesting finding was the nonconventional monoclinic nanocrystal nucleation and growth that occurred prior to transformation to the tetragonal phase (at 1,200 C) during the heat treatment of the nanocrystalline powders produced by the forced hydrolysis.

Hu, M.C.Z.; Hunt, R.D.; Payzant, E.A.; Hubbard, C.R. [Oak Ridge National Lab., TN (United States)

1999-09-01

167

Characteristics of nano-/ultrafine particle-bound PAHs in ambient air at an international airport.  

PubMed

Concentrations of 22 polycyclic aromatic hydrocarbons (PAHs) were estimated for individual particle-size distributions at the airport apron of the Taipei International Airport, Taiwan, on 48 days in July, September, October, and December of 2011. In total, 672 integrated air samples were collected using a micro-orifice uniform deposition impactor (MOUDI) and a nano-MOUDI. Particle-bound PAHs (P-PAHs) were analyzed by gas chromatography with mass selective detector (GC/MSD). The five most abundant species of P-PAHs on all sampling days were naphthalene (NaP), phenanthrene (PA), fluoranthene (FL), acenaphthene (AcP), and pyrene (Pyr). Total P-PAHs concentrations were 152.21, 184.83, and 188.94 ng/m(3) in summer, autumn, and winter, respectively. On average, the most abundant fractions of benzo[a]pyrene equivalent concentration (BaPeq) in different molecular weights were high-weight PAHs (79.29 %), followed by medium-weight PAHs (11.57 %) and low-weight PAHs (9.14 %). The mean BaPeq concentrations were 1.25 and 0.94 (ng/m(3)) in ultrafine particles (<0.1 ?m) and nano-particles (<0.032 ?m), respectively. The percentages of total BaPeq in nano- and ultrafine particulate size ranges were 52.4 % and 70.15 %, respectively. PMID:22821344

Lai, Chia-Hsiang; Chuang, Kuen-Yuan; Chang, Jin-Wei

2013-03-01

168

Reactive thermal plasmas: ultrafine particle synthesis and coating deposition  

Microsoft Academic Search

Thermal plasmas jets produced by d.c. arcs or RF discharges at pressures close to atmospheric pressure are characterized by the high temperatures (between 6000 and 14?000K) of heavy species and high velocities (between 100 and 2500ms?1) of plasma flow. They can be used either for their physical properties, i.e. acceleration and melting of solid particles (in the diameter range 10–100?m)

P. Fauchais; A. Vardelle; A. Denoirjean

1997-01-01

169

Individual dose and exposure of Italian children to ultrafine particles.  

PubMed

Time-activity patterns and the airborne pollutant concentrations encountered by children each day are an important determinant of individual exposure to airborne particles. This is demonstrated in this work by using hand-held devices to measure the real-time individual exposure of more than 100 children aged 8-11 years to particle number concentrations and average particle diameter, as well as alveolar and tracheobronchial deposited surface area concentration. A GPS-logger and activity diaries were also used to give explanation to the measurement results. Children were divided in three sample groups: two groups comprised of urban schools (school time from 8:30 am to 1:30 pm) with lunch and dinner at home, and the third group of a rural school with only dinner at home. The mean individual exposure to particle number concentration was found to differ between the three groups, ranging from 6.2 × 10(4)part.cm(-3) for children attending one urban school to 1.6 × 10(4)part.cm(-3) for the rural school. The corresponding daily alveolar deposited surface area dose varied from about 1.7 × 10(3)mm(2) for urban schools to 6.0 × 10(2)mm(2) for the rural school. For all of the children monitored, the lowest particle number concentrations are found during sleeping time and the highest were found during eating time. With regard to alveolar deposited surface area dose, a child's home was the major contributor (about 70%), with school contributing about 17% for urban schools and 27% for the rural school. An important contribution arises from the cooking/eating time spent at home, which accounted for approximately 20% of overall exposure, corresponding to more than 200 mm(2). These activities represent the highest dose received per time unit, with very high values also encountered by children with a fireplace at home, as well as those that spend considerable time stuck in traffic jams. PMID:23000716

Buonanno, G; Marini, S; Morawska, L; Fuoco, F C

2012-11-01

170

Source strengths of ultrafine and fine particles due to cooking with a gas stove.  

PubMed

Cooking, particularly frying, is an important source of particles indoors. Few studies have measured a full range of particle sizes, including ultrafine particles, produced during cooking. In this study, semicontinuous instruments with fine size discriminating ability were used to calculate particle counts in 124 size bins from 0.01 to 2.5 microm. Data were collected at 5 min intervals for 18 months in an occupied house. Tracer gas measurements were made every 10 min in each of 10 rooms of the house to establish air change rates. Cooking episodes (N = 44) were selected meeting certain criteria (high concentrations, no concurrent indoor sources, long smooth decay curves), and the number and volume of particles produced were determined for each size category. For each episode, the particle decay rate was determined and used to determine the source strength for each size category. The selected cooking episodes (mostly frying) were capable of producing about 10(14) particles over the length of the cooking period (about 15 min), more than 90% of them in the ultrafine (< 0.1 microm) range, with an estimated whole-house volume concentration of 50 (microm/cm)3. More than 60% of this volume occurred in the 0.1-0.3 microm range. Frying produced peak numbers of particles at about 0.06 microm, with a secondary peak at 0.01 microm. The peak volume occurred at a diameter of about 0.16 microm. Since the cooking episodes selected were biased toward higher concentrations, the particle concentrations measured during about 600 h of morning and evening cooking over a full year were compared to concentrations measured during noncooking periods at the same times. Cooking was capable of producing more than 10 times the ultrafine particle number observed during noncooking periods. Levels of PM2.5 were increased during cooking by a factor of 3. Breakfast cooking (mainly heating water for coffee and using an electric toaster) produced concentrations about half those produced from more complex dinnertime cooking. Although the number and volume concentrations observed depend on air change rates, house volume, and deposition rates due to fans and filters, the source strengths calculated here are independent of these variables and may be used to estimate number and volume concentrations in other types of homes with widely varying volumes, ventilation rates, and heating and air-conditioning practices. PMID:15116834

Wallace, Lance A; Emmerich, Steven J; Howard-Reed, Cynthia

2004-04-15

171

Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles  

SciTech Connect

A fundamental filtration study was started to investigate the separation of Fischer-Tropsch Synthesis (FTS) liquids from iron-based catalyst particles. Slurry-phase FTS in slurry bubble column reactor systems is the preferred mode of operation since the reaction is highly exothermic. Consequently, heavy wax products in one approach may be separated from catalyst particles before being removed from the reactor system. Achieving an efficient wax product separation from iron-based catalysts is one of the most challenging technical problems associated with slurry-phase iron-based FTS and is a key factor for optimizing operating costs. The separation problem is further compounded by attrition of iron catalyst particles and the formation of ultra-fine particles.

Amitava Sarkar; James K. Neathery; Burtron H. Davis

2006-12-31

172

Electronic State Characterization of TiO 2Ultrafine Particles by Luminescence Spectroscopy  

NASA Astrophysics Data System (ADS)

The electronic states of TiO 2ultrafine particles (UFP) are characterized by photoluminescence spectra and diffuse reflection spectra. The results obtained indicate that the surface structure, i.e., TiOH groups, TiOC 2H 5groups, and the defect state, plays an important role in the electronic states of the TiO 2UFP. Moreover, free exciton emission is observed at room temperature. This emission is attributed to the quantum confinement and the dielectric confinement effects on the TiO 2UFP.

Zhu, Yingchun; Ding, Chuanxian; Ma, Guohong; Du, Zuliang

1998-08-01

173

Investigation on the Surface State of TiO 2 Ultrafine Particles by Luminescence  

NASA Astrophysics Data System (ADS)

The surface states of TiO 2 ultrafine particles (UFP) are characterized by luminescence spectra and UV-absorption spectra. In order to confirm whether the emission at 475 nm originates from the surface state, the as-prepared TiO 2 UFP are plasma-treated. The results indicate that surface states related to the TiOH and TiOC 2H 5 groups play an important role in the emission and UV-absorption of TiO 2UFP. Both quantum confinement and dielectric confinement effects have been used for discussing the emission and UV-absorption properties of TiO 2 UFP.

Zhu, Ying Chun; Ding, Chuan Xian

1999-07-01

174

Electronic state characterization of TiO{sub 2} ultrafine particles by luminescence spectroscopy  

SciTech Connect

The electronic states of TiO{sub 2} ultrafine particles (UFP) are characterized by photoluminescence spectra and diffuse reflection spectra. The results obtained indicate that the surface structure, i.e., TiOH groups, TiOC{sub 2}H{sub 5} groups, and the defect state, plays an important role in the electronic states of the TiO{sub 2} UFP. Moreover, free exciton emission is observed at room temperature. This emission is attributed to the quantum confinement and the dielectric confinement effects on the TiO{sub 2} UFP.

Zhu, Y.; Ding, C. [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Ceramics] [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Ceramics; Ma, G.; Du, Z. [Henan Univ., Kaifeng (China). Lab. of Solid State Physics] [Henan Univ., Kaifeng (China). Lab. of Solid State Physics

1998-08-01

175

Urban and rural ultrafine (PM 0.1) particles in the Helsinki area  

NASA Astrophysics Data System (ADS)

In June 1996-June 1997 Berner low-pressure impactors were used at an urban and at a rural site in the Helsinki area for sampling ultrafine particles (UFP, PM 0.1). Ten sample pairs, each pair measured simultaneously, were collected in the size range of 0.03-15 ?m of particle aerodynamic diameter. More than 40 chemical components were measured. Surprisingly, the average UFP mass concentration was higher at the rural site (520 ng/m 3) than at the urban site (490 ng/m 3). The average chemical composition of UFP was similar at the two sites. The most abundant of the measured components were sulphate (32 and 40 ng/m 3 for the urban and rural sites, respectively), ammonium (22 and 25 ng/m 3), nitrate (4 and 11 ng/m 3) and the Ca 2+ ion (5 and 7 ng/m 3). The most important metals at both sites were Ca, Na, Fe, K and Zn with concentrations between 0.7 and 5 ng/m 3. Of the heavy metals, Ni, V, Cu, and Pb were important with average ultrafine concentrations between about 0.1 and 0.2 ng/m 3. Also the organic anions oxalate (urban 2.1 ng/m 3 and rural 1.9 ng/m 3) and methanesulphonate (1.3 and 1.7 ng/m 3) contributed similarly at both sites. The measured species accounted for only about 15-20% of the total ultrafine mass. The fraction that was not measured includes mainly carbonaceous material and water. It was estimated that the amount of water was about 10% (50 ng/m 3) and that of carbonaceous material about 70% (350 ng/m 3) at both sites. Aitken modes were observed for most components with the average mass mean mode diameters being between about 0.06 and 0.12 ?m. The average concentrations in the Aitken mode differed clearly from those in the UFP for several components. The average contribution of ultrafine mass to the fine particle mass (PM 2.5) was about 7% at the urban site and 8.5% at the rural site. At both sites the contribution of ultrafine to fine was especially high for Se, Ag, B, and Ni (10-20%) and at the rural site also for Co (20%), Ca 2+ (16%) and Mo (11%). Enrichment in the ultrafine particles suggests that local sources may exist for these elements. Aitken modes turned out to be useful indicators of local sources for several components. The Aitken modes of Ba, Ca, Mg and Sr were similar in several samples, suggesting a common local combustion source for these elements, possibly traffic exhaust. Co, Fe, Mo and Ni formed another group of elements often having similar Aitken modes, the likely source being combustion of heavy fuel oil.

Pakkanen, Tuomo A.; Kerminen, Veli-Matti; Korhonen, Christina H.; Hillamo, Risto E.; Aarnio, Päivi; Koskentalo, Tarja; Maenhaut, Willy

176

[Characterization of ultrafine particle size distribution in the urban atmosphere of Hangzhou in spring].  

PubMed

Continuous measurement and analysis of the atmospheric ultrafine particle number concentration were performed in Hangzhou from March to May, 2012 by using the fast mobility particle sizer (FMPS). The result showed that daily number concentration of nucleation mode (5.6-20 nm), Aitken mode (20-100 nm), and accumulation mode (100-560 nm) particles, and total particles were 0.84 x 10(4), 1.08 x 10(4), 0.47 x 10(4) and 2.38 x 10(4) cm(-3) respectively. The concentration of Aitken mode particles was higher than that of other mode particles in sunny day. The nucleation mode and Aitken mode particles usually started to increase around 10:00-11:00 and ended up after 3-4 h. This indicated the solar radiation promoted the formation of new particles. Human activities caused the concentration distribution of each mode particles having an obvious difference between workdays and weekends. Combined with the meteorological factors, analysis showed that the wind speed and wind direction also directly influenced particulate concentration. The analysis of particulate concentration and visibility showed that the concentration of accumulation mode particles had a negative relationship with the atmospheric visibility, while those of nucleation mode and Aitken mode particles had a slight influence on it. PMID:24812930

Xie, Xiao-Fang; Sun, Zai; Yang, Wen-Jun

2014-02-01

177

Diurnal and seasonal variations of ultrafine particle formation in anthropogenic SO2 plumes.  

PubMed

The cloud condensation nuclei concentrations predicted by global aerosol models are sensitive to how new particle formation in subgrid anthropogenic SO(2) plumes is parameterized. Using a state-of-the-art kinetic nucleation model, we carried out two case studies to investigate the large difference in the number concentrations of ultrafine particles observed in the plumes from the Horne smelter: one in the summer and the other in the winter. Our model predicted that particle number concentrations are in good agreement with observations for both cases, showing that particle formation in the Horne smelter plumes is dominated by binary homogeneous nucleation (BHN) in the winter case and by ion-mediated nucleation (IMN) in the summer case. Further sensitivity studies reveal significant diurnal and seasonal variations of sulfate particle formation in the anthropogenic SO(2) plume, mainly associated with corresponding variations of two key parameters: hydroxyl radical concentration ([OH]) and temperature. Nucleation in the plume is negligible at night because of very low [OH]. BHN is significant when [OH] is relatively high or temperature is relatively low, and it is generally limited to the fresh plumes (within approximately 15 km from source), but it can generate very high concentrations of ultrafine particles (peak values as high as 10(5)-10(6) cm(-3)) under favorable conditions. IMN generally dominates nucleation in the plume when [OH] is relatively low or temperature is relatively high, and it extends from fresh plume to more aged plume and produces 2-3 x 10(4) cm(-3) of nucleated particles. The implications of the results are discussed. PMID:20158231

Yu, Fangqun

2010-03-15

178

Measurements of Ultra-fine and Fine Aerosol Particles over Siberia: Large-scale Airborne Campaigns  

NASA Astrophysics Data System (ADS)

In this paper we discuss the results of in-situ measurements of ultra-fine and fine aerosol particles carried out in the troposphere from 500 to 7000 m in the framework of several International and Russian State Projects. Number concentrations of ultra-fine and fine aerosol particles measured during intensive airborne campaigns are presented. Measurements carried over a great part of Siberia were focused on particles with diameters from 3 to 21 nm to study new particle formation in the free/upper troposphere over middle and high latitudes of Asia, which is the most unexplored region of the Northern Hemisphere. Joint International airborne surveys were performed along the following routes: Novosibirsk-Salekhard-Khatanga-Chokurdakh-Pevek-Yakutsk-Mirny-Novosibirsk (YAK-AEROSIB/PLARCAT2008 Project) and Novosibirsk-Mirny-Yakutsk-Lensk-Bratsk-Novosibirsk (YAK-AEROSIB Project). The flights over Lake Baikal was conducted under Russian State contract. Concentrations of ultra-fine and fine particles were measured with automated diffusion battery (ADB, designed by ICKC SB RAS, Novosibirsk, Russia) modified for airborne applications. The airborne ADB coupled with CPC has an additional aspiration unit to compensate ambient pressure and changing flow rate. It enabled to classify nanoparticles in three size ranges: 3-6 nm, 6-21 nm, and 21-200 nm. To identify new particle formation events we used similar specific criteria as Young et al. (2007): (1) N3-6nm >10 cm-3, (2) R1=N3-6/N621 >1 and R2=N321/N21200 >0.5. So when one of the ratios R1 or R2 tends to decrease to the above limits the new particle formation is weakened. It is very important to notice that space scale where new particle formation was observed is rather large. All the events revealed in the FT occurred under clean air conditions (low CO mixing ratios). Measurements carried out in the atmospheric boundary layer over Baikal Lake did not reveal any event of new particle formation. Concentrations of ultra-fine particles were even lower than ones observed in the polar FT. Summarising the data obtained during two intensive measurement campaigns carried out over the vast territory of Siberia we can draw the conclusion that remote Siberian troposphere is a relatively efficient source of recently formed particles. Measurements carried out in the FT (3-7 km) showed that about 44% of them satisfied criteria of new particle formation. At the same time, more favourable conditions are observed between 5 and 7 km (48%). The present work was funded by ANR grant BLAN06-1_137670, CNRS, CEA, the French Ministry of Research, the French Ministry of Foreign Affairs (YAK-AEROSIB project) and by RFBR (grants 07-05-00645, 08-05-10033 and 08-05-92499) and by the Norwegian Research Council as part of POLARCAT-Norway. Flights over Baikal Lake were financed by Russian Government (State Contract No 02.515.11.5087). Young, L.H., Benson, D.R., Montanaro, W.M., Lee, S.H., Pan, L.L., Rogers, D.C., Jensen, J., Stith, J.L., Davis, C.A., Campos, T.L., Bowman, K.P., Cooper,W.A., Lait, L.R., 2007. Enhanced new particle formation observed in the northern midlatitude tropopause region. Journal of Geophysical Research 112. doi:10.1029/2006JD008109

Arshinov, Mikhail; Paris, Jean-Daniel; Stohl, Andreas; Belan, Boris; Ciais, Philippe; Nédélec, Philippe

2010-05-01

179

Engineering drug ultrafine particles of beclomethasone dipropionate for dry powder inhalation.  

PubMed

Beclomethasone dipropionate (BDP), which is a member in the inhaled glucocorticosteroid class, is commonly used in the treatment of asthma by pulmonary delivery. The purpose of this study is to prepare ultrafine BDP particles for dry powder inhalation (DPI) administration by combining microfluidic antisolvent precipitation without surfactant, high-pressure homogenization (HPH) and spray drying. T-junction microchannel was adopted for the preparation of needle-like BDP particles. The needle-like particles could be easily broken down into smaller particles during HPH, which were assembled into uniform low-density spherical BDP aggregates by spray drying. The effects of the operation parameters, such as the flow rates of BDP methanol solution and antisolvent, the overall flow rate, the BDP concentration, and the change of the injection phase on BDP particle size were explored. The results indicated that the BDP particle size greatly decreased with the reduction of BDP solution flow rate and the increase of antisolvent flow rate. However, the BDP particle size firstly decreased and then increased with the increase of the overall flow rate and the increase of BDP concentration. Also, BDP solution as the injection phase could form the smaller BDP particles. 10 HPH cycles are enough to forming short rod-like particles. After spray drying, the BDP spherical aggregates with a 2-3 ?m size could be achieved. They have an excellent aerosol performance, 2.8 and 1.4 times as many as raw BDP and vacuum-dried BDP particles, respectively. PMID:22732674

Xu, Li-Min; Zhang, Qian-Xia; Zhou, Yue; Zhao, Hong; Wang, Jie-Xin; Chen, Jian-Feng

2012-10-15

180

Formation of Ultrafine Cellular Microstructure Around Alumina Particles in a Low-Carbon Steel  

NASA Astrophysics Data System (ADS)

Ultrafine cellular microstructures around alumina particles in a low-carbon steel were observed, which survived even after cyclic austenitization. This indicates that their formation is closely related to internal stress because of a structural heterogeneity during phase transformation rather than to externally applied forces or deformation. Thermo-elasto-plastic finite element analysis confirmed the evolution of a large hydrostatic pressure around an alumina particle due to thermal mismatch during cooling. Therefore, the fine cellular microstructure might be generated as a result of the hydrostatic pressure, which retards the phase transformation around the particle during cooling. In addition, we observed microstructural similarity with the same steel processed under an ultra-high pressure, which was the evidence for the role of the delay in the transformation caused by the hydrostatic pressure.

Kang, Jun-Yun; Lee, Sang Hoon; Cho, Yi-Gil; Kim, Seul Cham; Cho, Hoon-Hwe; Han, Heung Nam; Oh, Kyu Hwan

2013-09-01

181

The surface properties and photocatalytic activities of ZnO ultrafine particles  

NASA Astrophysics Data System (ADS)

We prepared ZnO ultrafine particles (UFPs) by thermal decomposition of the precursor zinc carbonate hydroxide. The surface properties of the as-prepared particles were studied using TEM, XRD, BET, SPS, EPR, IR, and XPS. The surface contains active species such as oxygen deficiencies and hydroxyl that improve photocatalytic activities. The concentrations of active species decreased as the calcination temperature increased along with the surface areas and photovoltage. The ZnO UFP have a significant EPR signal resulting from O 2- deficiencies on the surface, which can capture and trap electrons. During photocatalytic degradation of phenol, the photocatalytic activities of the particles decreased as their size increased, which means that these activities depend mainly on surface properties.

Jing, Liqiang; Xu, Zili; Sun, Xiaojun; Shang, Jing; Cai, Weimin

2001-08-01

182

Exposure assessment in Beijing, China: biological agents, ultrafine particles, and lead.  

PubMed

In this study, air samples were taken using a BioSampler and gelatin filters from six sites in Beijing: office, hospital, student dormitory, train station, subway, and a commercial street. Dust samples were also collected using a surface sampler from the same environments. Limulus amoebocyte lysate (LAL) and Glucatell assays were used to quantify sample endotoxin and (1,3)-?-d-glucan concentration levels, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to measure the dust mite allergens (Der p 1 and Der f 1). Ultrafine particle and lead concentrations in these sampling sites were also measured using P-Trak and atomic absorption spectrometer, respectively. Analysis of variance (ANOVA) and linear regression analysis were used to analyze the concentration data. Higher culturable bacteria (12,639 CFU/m3) and fungi (1,806 CFU/m3) concentrations were observed for the train station and the subway system, respectively. For the rest of sampling sites, their concentrations were comparable to those found in western countries, ranging from 990 to 2,276 CFU/m3 for bacteria, and from 119 to 269 CFU/m3 for fungi. ANOVA analysis indicated that there were statistically significant differences between the culturable bacterial and fungal concentration levels obtained for different sites (p value=0.0001 and 0.0047). As for dust allergens, endotoxin, and (1,3)-?-D-glucan, their concentrations also seemed to be comparable to those found in the developed countries. Airborne allergen concentrations ranged from 16 to 68 ng/m3. The dust-borne allergen concentration was observed to range from 0.063 to 0.327 ng/mg. As for endotoxin, the highest airborne concentration of 25.24 ng/m3 was observed for the commercial street, and others ranged from 0.0427 to 0.1259 ng/m3. And dust-borne endotoxin concentration ranged from 58.83 to 6,427.4 ng/mg. For (1,3)-?-D-glucan, the airborne concentration ranged from 0.02 to 1.2 ng/m3. Linear regression analyses showed that there existed poor correlations between those in airborne and dust-borne states (R2=0.002~0.43). In our study, the lowest ultrafine particle concentration about 5,203 pt/cm3 was observed in office and the highest was observed at the train station, up to 32,783 pt/cm3. Lead concentration was shown to range from 80 to 170 ng/mg with the highest also observed at the train station. The information provided in this work can be used to learn the general situation of relevant health risks in Beijing. And the results here suggested that when characterizing exposure both airborne and dust-borne as well as the environments should be considered. PMID:19904623

Dong, Shuofei; Yao, Maosheng

2010-11-01

183

Perspectives on individual to ensembles of ambient fine and ultrafine particles and their sources  

NASA Astrophysics Data System (ADS)

By combining Rapid Single-ultrafine-particle Mass Spectrometry (RSMS) measurements during the Pittsburgh Supersite experiment with a large array of concurrent PM, gas and meteorological data, a synthesis of data and analyses is employed to characterize sources, emission trends and dynamics of ambient fine and ultrafine particles. Combinatorial analyses elicit individual to ensemble descriptions of particles, their sources, their changes in state from atmospheric processing and the scales of motion driving their transport and dynamics. Major results include (1) Particle size and composition are strong indicators of sources/source categories and real-time measurements allow source attribution at the single particle and point source level. (2) Single particle source attribution compares well to factor analysis of chemically-speciated bulk phase data and both resulted in similar conclusions but independently revealed new sources. (3) RSMS data can quantitatively estimate composition-resolved, number-based particle size distribution. Comparison to mass-based data yielded new information about physical and chemical properties of particles and instrument sensitivity. (4) Source-specific signatures and real-time monitoring allow passing plumes to be tracked and characterized. (5) The largest of three identified coal combustion sources emits ˜ 2.4 x 10 17 primary submicron particles per second. (6) Long-range transport has a significant impact on the eastern U.S. including specific influences of eight separate wildfire events. (7) Pollutant dynamics in the Pittsburgh summertime air shed, and Northeastern U.S., is characterized by alternating periods of stagnation and cleansing. The eight wildfire events were detected in between seven successive stagnation events. (8) Connections exist between boreal fire activity, southeast subsiding transport of the emissions, alternating periods of stagnation and cleansing at the receptor and the structure and propagation of extratropical waves. (9) Wildfire emissions can severely impact preexisting pollutant concentrations and physical and chemical processes at the receptor. (10) High-severity crown fires in boreal Canada emit ˜ 1.2 x 1015 particles/kg biomass burned. (11) In 1998, wildfire activity in the circumpolar boreal forest emitted ˜ 8 x 1026 particles, representing ˜ 14% of global wildland fire emissions. Results and conclusions address future scientific objectives in understanding effects of particles on human health and global climate change.

Bein, Keith James

184

Measurement of Ultrafine Particles and Other Air Pollutants Emitted by Cooking Activities  

PubMed Central

Cooking emissions show a strong dependence on cooking styles and parameters. Measurements of the average ultrafine particle (UFP) concentration, PM2.5 and black carbon concentrations emitted by cooking activities ranged from 1.34 × 104 to 6.04 × 105 particles/cm3, 10.0 to 230.9 ?g/m3 and 0.1 to 0.8 ?g/m3, respectively. Lower UFP concentrations were observed during boiling, while higher levels were emitted during frying. The highest UFP concentrations were observed when using a gas stove at high temperature with the kitchen exhaust fan turned off. The observed UFP profiles were similar in the kitchen and in another room, with a lag of approximately 10 min.

Zhang, Qunfang; Gangupomu, Roja H.; Ramirez, David; Zhu, Yifang

2010-01-01

185

ECG Parameters and Exposure to Carbon Ultrafine Particles in Young Healthy Subjects  

PubMed Central

The mechanisms underlying the association between air pollution and cardiovascular morbidity and mortality are unknown. This study aimed to determine whether controlled exposure to elemental carbon ultrafine particles (UFP) affects electrocardiogram (ECG) parameters describing heart rate variability; repolarization duration, morphology, and variability; and changes in the ST segment. Two separate controlled studies (12 subjects each) were performed using a crossover design, in which each subject was exposed to filtered air and carbon UFP for 2 hours. The first protocol involved 2 exposures to air and 10 µg/m3 (~ 2 × 106 particles/cm3, count median diameter ~25 nm, geometric standard deviation ~1.6), at rest. The second protocol included 3 exposures to air, 10, and 25 µg/m3 UFP (~ 7 × 106 particles/cm3), with repeated exercise. Each subject underwent a continuous digital 12-lead ECG Holter recording to analyze the above ECG parameters. Repeated measures analysis of variance (ANOVA) was used to compare tested parameters between exposures. The observed responses to UFP exposure were small and generally not significant, although there were trends indicating an increase in parasympathetic tone, which is most likely also responsible for trends toward ST elevation, blunted QTc shortening, and increased variability of T-wave complexity after exposure to UFP. Recovery from exercise showed a blunted response of the parasympathetic system after exposure to UFP in comparison to air exposure. In conclusion, transient exposure to 10–25 µg/m3 ultrafine carbon particles does not cause marked changes in ECG-derived parameters in young healthy subjects. However, trends are observed indicating that some subjects might be susceptible to air pollution, with a response involving autonomic modulation of the heart and repolarization of the ventricular myocardium.

Zareba, Wojciech; Couderc, Jean Philippe; Oberdorster, Gunter; Chalupa, David; Cox, Christopher; Huang, Li-Shan; Peters, Annette; Utell, Mark J.; Frampton, Mark W.

2010-01-01

186

Size-dependent hydroxyl radicals generation induced by SiO 2 ultra-fine particles: The role of surface iron  

Microsoft Academic Search

Oxidative stress and hydroxyl radicals (·OH) play important roles in adverse health effects caused by inhalable ambient air\\u000a particles (PM10). The ultra-fine fraction of PM10 has been hypothesized as one of the critical contributors to ·OH generation. Both in vivo and in vitro studies have shown that ultra-fine particles (UFPs) or nano-particles generate more ·OH than larger particles with identical

Yu Shang; Tong Zhu; Yi Li; JinCai Zhao

2009-01-01

187

Exposure to ultrafine particles in hospitality venues with partial smoking bans.  

PubMed

Fine particles in hospitality venues with insufficient smoking bans indicate health risks from passive smoking. In a random sample of Viennese inns (restaurants, cafes, bars, pubs and discotheques) effects of partial smoking bans on indoor air quality were examined by measurement of count, size and chargeable surface of ultrafine particles (UFPs) sized 10-300 nm, simultaneously with mass of particles sized 300-2500 nm (PM2.5). Air samples were taken in 134 rooms unannounced during busy hours and analyzed by a diffusion size classifier and an optical particle counter. Highest number concentrations of particles were found in smoking venues and smoking rooms (median 66,011 pt/cm(3)). Even non-smoking rooms adjacent to smoking rooms were highly contaminated (median 25,973 pt/cm(3)), compared with non-smoking venues (median 7408 pt/cm(3)). The particle number concentration was significantly correlated with the fine particle mass (P<0.001). We conclude that the existing tobacco law in Austria is ineffective to protect customers in non-smoking rooms of hospitality premises. Health protection of non-smoking guests and employees from risky UFP concentration is insufficient, even in rooms labeled "non-smoking". Partial smoking bans with separation of smoking rooms failed. PMID:23652720

Neuberger, Manfred; Moshammer, Hanns; Schietz, Armin

2013-01-01

188

CONTINUOUS MONITORING OF ULTRAFINE, FINE, AND COARSE PARTICLES IN A RESIDENCE FOR 18 MONTHS IN 1999-2000  

EPA Science Inventory

Continuous monitors were employed for 18 months in an occupied townhouse to measure ultrafine, fine, and coarse particles; air change rates; wind speed and direction; temperature; and relative humidity (RH). A main objective was to document short-term and long-term variation in...

189

INCREASED IL-8 AND IL-6 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES  

EPA Science Inventory

INCREASED IL-6 AND IL-8 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES. R Silbajoris1, A G Lenz2, I Jaspers3, J M Samet1. 1NHEERL, USEPA, RTP, NC, USA; 2GSF-Institute for Inhalation Biology, Neuherberg, Germany; 3 CEMLB, UNC-CH, Chapel Hill, ...

190

Separation of fischer Tropsch Wax Products for Ultrafine Iron Catalyst Particles. Technical Progress Report for Reporting Period fo April 1, 2005-September 30, 2005  

National Technical Information Service (NTIS)

In this reporting period, a study of ultra-fine iron catalyst filtration was initiated to study the behavior of ultra-fine particles during the separation of Fischer-Tropsch Synthesis (FTS) liquids filtration. The overall focus of the program is with slur...

A. Sarkar B. H. Davis G. Jacobs J. K. Neathery

2005-01-01

191

Comparisons of Ultrafine and Fine Particles in Their Associations with Biomarkers Reflecting Physiological Pathways  

PubMed Central

Using a quasi-experimental opportunity offered by greatly restricted air pollution emissions during the Beijing Olympics compared to before and after the Olympics, we conducted the current study to compare ultrafine particles (UFPs) and fine particles (PM2.5) in their associations with biomarkers reflecting multiple pathophysiological pathways linking exposure and cardiorespiratory events. Number concentrations of particles (13.0–764.7 nm) and mass concentrations of PM2.5 were measured at two locations within 9 km from the residence and workplace of 125 participating Beijing residents. Each participant was measured 6 times for biomarkers of autonomic function (heart rate, systolic and diastolic blood pressures), hemostasis (von Willebrand factor, soluble CD40 ligand, and P-selectin), pulmonary inflammation and oxidative stress (exhaled nitric oxide and exhaled breath condensate pH, malondialdehyde, and nitrite), and systemic inflammation and oxidative stress (urinary malondialdehyde and 8-hydroxy-2?-deoxyguanosine, plasma fibrinogen, and white blood cells). Linear mixed models were used to estimate associations of biomarkers with UFPs and PM2.5 measured 1–7 days prior to biomarker measurements (lags). We found that the correlation coefficient for UFPs at two locations (?9 km apart) was 0.45, and at the same location, the correlation coefficient for PM2.5 vs UFPs was ?0.18. Changes in biomarker levels associated with increases in UFPs and PM2.5 were comparable in magnitude. However, associations of certain biomarkers with UFPs had different lag patterns compared to those with PM2.5, suggesting that the ultrafine size fraction (?100 nm) and the fine size fraction (?100 nm to 2.5 ?m) of PM2.5 are likely to affect PM-induced pathophysiological pathways independently.

2014-01-01

192

Comparisons of ultrafine and fine particles in their associations with biomarkers reflecting physiological pathways.  

PubMed

Using a quasi-experimental opportunity offered by greatly restricted air pollution emissions during the Beijing Olympics compared to before and after the Olympics, we conducted the current study to compare ultrafine particles (UFPs) and fine particles (PM2.5) in their associations with biomarkers reflecting multiple pathophysiological pathways linking exposure and cardiorespiratory events. Number concentrations of particles (13.0-764.7 nm) and mass concentrations of PM2.5 were measured at two locations within 9 km from the residence and workplace of 125 participating Beijing residents. Each participant was measured 6 times for biomarkers of autonomic function (heart rate, systolic and diastolic blood pressures), hemostasis (von Willebrand factor, soluble CD40 ligand, and P-selectin), pulmonary inflammation and oxidative stress (exhaled nitric oxide and exhaled breath condensate pH, malondialdehyde, and nitrite), and systemic inflammation and oxidative stress (urinary malondialdehyde and 8-hydroxy-2'-deoxyguanosine, plasma fibrinogen, and white blood cells). Linear mixed models were used to estimate associations of biomarkers with UFPs and PM2.5 measured 1-7 days prior to biomarker measurements (lags). We found that the correlation coefficient for UFPs at two locations (?9 km apart) was 0.45, and at the same location, the correlation coefficient for PM2.5 vs UFPs was -0.18. Changes in biomarker levels associated with increases in UFPs and PM2.5 were comparable in magnitude. However, associations of certain biomarkers with UFPs had different lag patterns compared to those with PM2.5, suggesting that the ultrafine size fraction (?100 nm) and the fine size fraction (?100 nm to 2.5 ?m) of PM2.5 are likely to affect PM-induced pathophysiological pathways independently. PMID:24666379

Gong, Jicheng; Zhu, Tong; Kipen, Howard; Wang, Guangfa; Hu, Min; Guo, Qingfeng; Ohman-Strickland, Pamela; Lu, Shou-En; Wang, Yuedan; Zhu, Ping; Rich, David Q; Huang, Wei; Zhang, Junfeng

2014-05-01

193

Ultrafine particle emissions from essential-oil-based mosquito repellent products.  

PubMed

Ultrafine particle (UFP) emissions from three essential-oil-based mosquito repellent products (lemon eucalyptus (LE), natural insects (NI), and bite shield (BS)) were tested in a 386 l chamber at a high air exchange rate of 24/h with filtered laboratory air. Total particle number concentration and size distribution were monitored by a condensation particle counter and a scanning mobility particle sizer, respectively. UFPs were emitted from all three products under indoor relevant ozone concentrations (~ 17 ppb). LE showed a nucleation burst followed by a relatively stable and continuous emission while the other two products (NI and BS) showed episodic emissions. The estimated maximum particle emission rate varied from 5.4 × 10(9) to 1.2 × 10(12) particles/min and was directly related to the dose of mosquito repellent used. These rates are comparable to those due to other indoor activities such as cooking and printing. The emission duration for LE lasted for 8-78 min depending on the dose applied while the emission duration for NI and BS lasted for 2-3 h. PMID:24245647

Liu, J; Fung, D; Jiang, J; Zhu, Y

2014-06-01

194

Ultrafine particle size distributions near freeways: Effects of differing wind directions on exposure  

NASA Astrophysics Data System (ADS)

High ambient ultrafine particle (UFP) concentrations may play an important role in the adverse health effects associated with living near busy roadways. However, UFP size distributions change rapidly as vehicle emissions dilute and age. These size changes can influence UFP lung deposition rates and dose because deposition in the respiratory system is a strong function of particle size. Few studies to date have measured and characterized changes in near-road UFP size distributions in real-time, thus missing transient variations in size distribution due to short-term fluctuations in wind speed, direction, or particle dynamics. In this study we measured important wind direction effects on near-freeway UFP size distributions and gradients using a mobile platform with 5-s time resolution. Compared to more commonly measured perpendicular (downwind) conditions, parallel wind conditions appeared to promote formation of broader and larger size distributions of roughly one-half the particle concentration. Particles during more parallel wind conditions also changed less in size with downwind distance and the fraction of lung-deposited particle number was calculated to be 15% lower than for downwind conditions, giving a combined decrease of about 60%. In addition, a multivariate analysis of several variables found meteorology, particularly wind direction and temperature, to be important in predicting UFP concentrations within 150 m of a freeway (R2 = 0.46, p = 0.014).

Kozawa, Kathleen H.; Winer, Arthur M.; Fruin, Scott A.

2012-12-01

195

Water Condensation Growth Cells for Ultrafine Particle Collection Onto Concentrated Spots  

NASA Astrophysics Data System (ADS)

A laminar flow, condensation method, analogous to that employed in the water-based condensation particle counters, is utilized to provide concentrated, low-pressure drop collection of fine and ultrafine particles. With the laminar flow water condensation approach, the aerosol flow is first chilled by a cold walled conditioner, and then introduced into a hot wet-walled condenser. Because water vapor diffuses more rapidly then heat, the air vapor is supersaturated resulting in particles large enough to be collected by impaction. Several types of collectors have been designed and tested. A compact system utilizing a single TED as a heat pump to provide a ~ 25 ° C temperature difference provides collection at 0.4 L/min with a lower cutpoint of 10 nm, a pressure drop of 1 kPa, and a power consumption of 1 Watt. A larger, parallel plate system samples at 10 L/min, and yields a cutpoint of 20 nm. The design of these systems was guided by numeric modeling of the saturation ratios, particle activation and growth. The model includes the heat release from condensation, and the associated warming of the flow that reduces the supersaturation and particle growth at high particle number concentrations. By controlling the system geometry (either plate separation or tube diameter), we are able to activate at small particle sizes while minimizing concentration effects. Our method of particle collection provides a number of other advantages. Particle bounce off the impaction surface can be eliminated by controlling the temperature of the impaction surface so as to maintain a thin film of water on the surface. Particles can also be collected into a small liquid vial containing less then 1 ml of fluid, which eliminates the need for particle extraction from filters or resuspension from surface, it minimizes the total volume of the sample, and it allows for continuous automated collection and analysis.

Lewis, G. S.; Hering, S. V.; Kreisberg, N.

2007-12-01

196

Real-time gaseous, PM and ultrafine particle emissions from a modern marine engine operating on biodiesel.  

PubMed

Emissions from harbor-craft significantly affect air quality in populated regions near ports and inland waterways. This research measured regulated and unregulated emissions from an in-use EPA Tier 2 marine propulsion engine on a ferry operating in a bay following standard methods. A special effort was made to monitor continuously both the total Particulate Mass (PM) mass emissions and the real-time Particle Size Distribution (PSD). The engine was operated following the loads in ISO 8178-4 E3 cycle for comparison with the certification standards and across biodiesel blends. Real-time measurements were also made during a typical cruise in the bay. Results showed the in-use nitrogen oxide (NOx) and PM(2.5) emission factors were within the not to exceed standard for Tier 2 marine engines. Comparing across fuels we observed the following: a) no statistically significant change in NO(x) emissions with biodiesel blends (B20, B50); b) ? 16% and ? 25% reduction of PM(2.5) mass emissions with B20 and B50 respectively; c) a larger organic carbon (OC) to elemental carbon (EC) ratio and organic mass (OM) to OC ratio with B50 compared to B20 and B0; d) a significant number of ultrafine nuclei and a smaller mass mean diameter with increasing blend-levels of biodiesel. The real-time monitoring of gaseous and particulate emissions during a typical cruise in the San Francisco Bay (in-use cycle) revealed important effects of ocean/bay currents on emissions: NO(x) and CO(2) increased 3-fold; PM(2.5) mass increased 6-fold; and ultrafine particles disappeared due to the effect of bay currents. This finding has implications on the use of certification values instead of actual in-use emission values when developing inventories. Emission factors for some volatile organic compounds (VOCs), carbonyls, and poly aromatic hydrocarbons (PAHs) are reported as supplemental data. PMID:21344849

Jayaram, Varalakshmi; Agrawal, Harshit; Welch, William A; Miller, J Wayne; Cocker, David R

2011-03-15

197

Chemical, dimensional and morphological ultrafine particle characterization from a waste-to-energy plant.  

PubMed

Waste combustion processes are responsible of particles and gaseous emissions. Referring to the particle emission, in the last years specific attention was paid to ultrafine particles (UFPs, diameter less than 0.1 ?m), mainly emitted by combustion processes. In fact, recent findings of toxicological and epidemiological studies indicate that fine and ultrafine particles could represent a risk for health and environment. Therefore, it is necessary to quantify particle emissions from incinerators also to perform an exposure assessment for the human populations living in their surrounding areas. To these purposes, in the present work an experimental campaign aimed to monitor UFPs was carried out at the incineration plant in San Vittore del Lazio (Italy). Particle size distributions and total concentrations were measured both at the stack and before the fabric filter inlet in order to evaluate the removal efficiency of the filter in terms of UFPs. A chemical characterization of UFPs in terms of heavy metal concentration was performed through a nuclear method, i.e., Instrumental Neutron Activation Analysis (INAA), as well as a mineralogical investigation was carried out through a Transmission Electron Microscope (TEM) equipped with an Energy Dispersive Spectrometer (EDS) in order to evaluate shape, crystalline state and mineral compound of sampled particles. Maximum values of 2.7 × 10(7) part. cm(-3) and 2.0 × 10(3) part. cm(-3) were found, respectively, for number concentration before and after the fabric filter showing a very high efficiency in particle removing by the fabric filter. With regard to heavy metal concentrations, the elements with higher boiling temperature present higher concentrations at lower diameters showing a not complete evaporation in the combustion section and the consequent condensation of semi-volatile compounds on solid nuclei. In terms of mineralogical and morphological analysis, the most abundant compounds found in samples collected before the fabric filter are Na-K-Pb oxides followed by phyllosilicates, otherwise, different oxides of comparable abundance were detected in the samples collected at the stack. PMID:21802934

Buonanno, Giorgio; Stabile, Luca; Avino, Pasquale; Belluso, Elena

2011-11-01

198

XRF-analysis of fine and ultrafine particles emitted from laser printing devices.  

PubMed

In this work, the elemental composition of fine and ultrafine particles emitted by ten different laser printing devices (LPD) is examined. The particle number concentration time series was measured as well as the particle size distributions. In parallel, emitted particles were size-selectively sampled with a cascade impactor and subsequently analyzed by the means of XRF. In order to identify potential sources for the aerosol's elemental composition, materials involved in the printing process such as toner, paper, and structural components of the printer were also analyzed. While the majority of particle emissions from laser printers are known to consist of recondensated semi volatile organic compounds, elemental analysis identifies Si, S, Cl, Ca, Ti, Cr, and Fe as well as traces of Ni and Zn in different size fractions of the aerosols. These elements can mainly be assigned to contributions from toner and paper. The detection of elements that are likely to be present in inorganic compounds is in good agreement with the measurement of nonvolatile particles. Quantitative measurements of solid particles at 400 °C resulted in residues of 1.6 × 10(9) and 1.5 × 10(10) particles per print job, representing fractions of 0.2% and 1.9% of the total number of emitted particles at room temperature. In combination with the XRF results it is concluded that solid inorganic particles contribute to LPD emissions in measurable quantities. Furthermore, for the first time Br was detected in significant concentrations in the aerosol emitted from two LPD. The analysis of several possible sources identified the plastic housings of the fuser units as main sources due to substantial Br concentrations related to brominated flame retardants. PMID:21809840

Barthel, Mathias; Pedan, Vasilisa; Hahn, Oliver; Rothhardt, Monika; Bresch, Harald; Jann, Oliver; Seeger, Stefan

2011-09-15

199

Ultrafine particles and nitrogen oxides generated by gas and electric cooking  

PubMed Central

OBJECTIVES—To measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens.?METHODS—Experiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NOx) were measured by a chemiluminescent ML9841A NOx analyser. A TSI 3934 scanning mobility particle sizer was used to measure average number concentration and size distribution of aerosols in the size range 10-500 nm.?RESULTS—High concentrations of particles are generated by gas combustion, by frying, and by cooking of fatty foods. Electric rings and grills may also generate particles from their surfaces. In experiments where gas burning was the most important source of particles, most particles were in the size range 15-40 nm. When bacon was fried on the gas or electric rings the particles were of larger diameter, in the size range 50-100 nm. The smaller particles generated during experiments grew in size with time because of coagulation. Substantial concentrations of NOX were generated during cooking on gas; four rings for 15 minutes produced 5 minute peaks of about 1000 ppb nitrogen dioxide and about 2000 ppb nitric oxide.?CONCLUSIONS—Cooking in a poorly ventilated kitchen may give rise to potentially toxic concentrations of numbers of particles. Very high concentrations of oxides of nitrogen may also be generated by gas cooking, and with no extraction and poor ventilation, may reach concentrations at which adverse health effects may be expected. Although respiratory effects of exposure to NOx might be anticipated, recent epidemiology suggests that cardiac effects cannot be excluded, and further investigation of this is desirable.???Keywords: cooking fuels; nitrogen oxides; ultrafine particles

Dennekamp, M; Howarth, S; Dick, C; Cherrie, J; Donaldson, K; Seaton, A

2001-01-01

200

Production of ultrafine, high-purity ceramic powders using the US Bureau of Mines developed turbomill  

NASA Technical Reports Server (NTRS)

Turbomilling, an innovative grinding technology developed by the U.S. Bureau of Mines in the early 1960's for delaminating filler-grade kaolinitic clays, has been expanded into the areas of particle size reduction, material mixing, and process reaction kinetics. The turbomill, originally called an attrition grinder, has been used for particle size reduction of many minerals, including natural and synthetic mica, pyrophyllite, talc, and marble. In recent years, an all-polymer version of the turbomill has been used to produce ultrafine, high-purity, advanced ceramic powders such as SiC, Si3N4, TiB2, and ZrO2. In addition to particle size reduction, the turbomill has been used to produce intimate mixtures of high surface area powders and whiskers. Raw materials, TiN, AlN, and Al2O3, used to produce a titanium nitride/aluminum oxynitride (TiN/AlON) composite, were mixed in the turbomill, resulting in strength increases over samples prepared by dry ball milling. Using the turbomill as a leach vessel, it was found that 90.4 pct of the copper was extracted from the chalcopyrite during a 4-hour leach test in ferric sulfate versus conventional processing which involves either roasting of the ore for Cu recovery or leaching of the ore for several days.

Hoyer, Jesse L.

1993-01-01

201

Thin glass film between ultrafine conductor particles in thick-film resistors  

SciTech Connect

Thick-film resistors are electrical composites containing ultrafine particles of ruthenate conductor (Pb[sub 2]Ru[sub 2]O[sub 7] in the present materials) distributed in a highly modified silicate glass. The authors show that conductor particles remain flocced in the absence of any applied or capillary pressures, but are separated at equilibrium by a nanometer-thick film of glass. Microstructures show evidence for liquid-phase sintering, i.e., contact flattening of particles, under van der Waals attraction alone. Titania addition, which in dilute concentrations markedly increases the resistivity, decreases the temperature coefficient of resistance, and improves voltage stability and noise, is found to increase the equilibrium film thickness between particles by a few angstroms. STEM analyses show that the added titania preferentially concentrates in the silicate-rich grain boundary film, as well as at particle-glass interfaces. The roles of interparticle forces and adsorption on the glass film thickness with and without titania are discussed. The large increase in resistivity caused by titania additions is attributed to the increase in film thickness as well as to local chemical changes of two possible types. Titania enrichment within the glass film itself is expected to decrease the local ruthenium ion solubility, and this along with the possible formation of a more insulating titania-substituted surface layer on ruthenate grains will decrease the tunneling conductivity between conductor grains.

Chiang, Y.M. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering); Silverman, L.A.; French, R.H. (DuPont Co., Wilmington, DE (United States). Central Research and Development); Cannon, R.M. (Lawrence Berkeley Lab., CA (United States))

1994-05-01

202

Aerosol Measurements of the Fine and Ultrafine Particle Content of Lunar Regolith  

NASA Technical Reports Server (NTRS)

We report the first quantitative measurements of the ultrafine (20 to 100 nm) and fine (100 nm to 20 m) particulate components of Lunar surface regolith. The measurements were performed by gas-phase dispersal of the samples, and analysis using aerosol diagnostic techniques. This approach makes no a priori assumptions about the particle size distribution function as required by ensemble optical scattering methods, and is independent of refractive index and density. The method provides direct evaluation of effective transport diameters, in contrast to indirect scattering techniques or size information derived from two-dimensional projections of high magnification-images. The results demonstrate considerable populations in these size regimes. In light of the numerous difficulties attributed to dust exposure during the Apollo program, this outcome is of significant importance to the design of mitigation technologies for future Lunar exploration.

Greenberg, Paul S.; Chen, Da-Ren; Smith, Sally A.

2007-01-01

203

Temperature dependence of the dynamics of ultrafine particles in a polymeric network  

NASA Astrophysics Data System (ADS)

Simple model systems with pronounced dynamical features will help to get a deeper insight into the complicated dynamics of large molecular networks. We investigated the bounded diffusion of ultrafine Fe(OH)3 particles (˜30 Å in diameter) in the three-dimensional network of the cation exchanger Dowex 50 W which was solvated with a water solution of sucrose (60 wt%). Mössbauer spectra were recorded in the temperature range from 80 K to 305 K. At temperatures above 250 K broad diffusional lines of different widths appear in the spectrum proving the bounded nature of the diffusion. The line widths strongly increase with temperature to values of several hundred mm/s. Around 300 K a large portion of the area escapes even from the largest window of observation used in our experiments (±550 mm/s).

Nienhaus, G. U.; Plachinda, A. S.; Fischer, M.; Khromov, V. I.; Parak, F.; Suzdalev, I. P.; Goldanskii, V. I.

1990-07-01

204

Investigation on the surface state of TiO{sub 2} ultrafine particles by luminescence  

SciTech Connect

The surface states of TiO{sub 2} ultrafine particles (UFP) are characterized by luminescence spectra and UV-absorption spectra. In order to confirm whether the emission at 475 nm originates from the surface state, the as-prepared TiO{sub 2} UFP are plasma-treated. The results indicate that surface states related to the TiOH and TiOC{sub 2}H{sub 5} groups play an important role in the emission and UV-absorption of TiO{sub 2}UFP. Both quantum confinement and dielectric confinement effects have been used for discussing the emission and UV-absorption properties of TiO{sub 2} UFP.

Zhu, Y.C.; Ding, C.X. [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Ceramics] [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Ceramics

1999-07-01

205

Comparison of the Biological Activity Between Ultrafine and Fine Titanium Dioxide Particles in RAW 264.7 Cells Associated with Oxidative Stress  

Microsoft Academic Search

Ultrafine or fine titanium dioxide (TiO2) particles are widely used in the production of white pigments, for sunscreens, and in cleanup techniques. However, currently knowledge is deficient concerning cellular responses to these particles. The study evaluated and compared the biological activity of ultrafine and fine TiO2 particles in RAW 264.7 macrophages according to an oxidative stress paradigm. In vitro exposure

Jihee Lee Kang; Changsuk Moon; Hui Su Lee; Hae Won Lee; Eun-Mi Park; Hee Sun Kim; Vincent Castranova

2008-01-01

206

Long-term study of urban ultrafine particles and other pollutants  

NASA Astrophysics Data System (ADS)

Continuous measurements of number size distributions of ultrafine particles (UFPs) and other pollutants (PM 2.5, SO 2, CO and O 3) have been performed in Rochester, New York since late November 2001. The 2002-2009 average number concentrations of particles in three size ranges (10-50 nm, 50-100 nm and 100-500 nm) were 4730 cm -3, 1838 cm -3, and 1073 cm -3, respectively. The lowest annual average number concentrations of particles in 10-50 nm and 50-100 nm were observed during 2008-2009. The lowest monthly average number concentration of 10-50 nm particles was observed in July and the highest in February. The daily patterns of 10-50 nm particles had two peaks at early morning (7-8 AM) and early afternoon (2 PM). There was a distinct declining trend in the peak number concentrations from 2002-2005 to 2008-2009. Large reductions in SO 2 concentrations associated with northerly winds between 2007 and 2009 were observed. The most significant annual decrease in the frequency of morning particle nucleation was observed from 2005 to 2007. The monthly variation in the morning nucleation events showed a close correlation with number concentrations of 10-50 nm particles ( r = 0.89). The frequency of the local SO 2-related nucleation events was much higher before 2006. All of these results suggest significant impacts of highway traffic and industrial sources. The decrease in particle number concentrations and particle nucleation events likely resulted from a combination of the U.S. EPA 2007 Heavy-Duty Highway Rule implemented on October 1, 2006, the closure of a large coal-fired power plant in May 2008, and the reduction of Eastman Kodak emissions.

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

2011-12-01

207

Ultrafine titanium dioxide particles in the absence of photoactivation can induce oxidative damage to human bronchial epithelial cells  

Microsoft Academic Search

Ultrafine titanium dioxide (TiO2) particles have been shown to exhibit strong cytotoxicity when exposed to UVA radiation, but are regarded as a biocompatible material in the absence of photoactivation. In contrast to this concept, the present results indicate that anatase-sized (10 and 20nm) TiO2 particles in the absence of photoactivation induced oxidative DNA damage, lipid peroxidation, and micronuclei formation, and

Jia-Ran Gurr; Alexander S. S. Wang; Chien-Hung Chen; Kun-Yan Jan

2005-01-01

208

Spatial distribution of ultrafine particles in urban settings: A land use regression model  

NASA Astrophysics Data System (ADS)

BackgroundThe toxic effects of ultrafine particles (UFP) are a public health concern. However, epidemiological studies on the long term effects of UFP are limited due to lacking exposure models. Given the high spatial variation of UFP, the assignment of exposure levels in epidemiological studies requires a fine spatial scale. The aim of this study was to assess the performance of a short-term measurement protocol used at a large number of locations to derive a land use regression (LUR) model of the spatial variation of UFP in Girona, Spain. MethodsWe measured UFP for 15 min on the sidewalk of 644 participants' homes in 12 towns of Girona province (Spain). The measurements were done during non-rush traffic hours 9:15-12:45 and 15:15-16:45 during 32 days between June 15 and July 31, 2009. In parallel, we counted the number of vehicles driving in both directions. Measurements were repeated on a different day for a subset of 25 sites in Girona city. Potential predictor variables such as building density, distance to bus lines and land cover were derived using geographic information systems. We adjusted for temporal variation using daily mean NOx concentrations at a central monitor. Land use regression models for the entire area (Core model) and for individual towns were derived using a supervised forward selection algorithm. ResultsThe best predictors of UFP were traffic intensity, distance to nearest major crossroad, area of high density residential land and household density. The LUR Core model explained 36% of UFP total variation. Adding sampling date and hour of the day to the Core model increased the R2 to 51% without changing the regression slopes. Local models included predictor variables similar to those in the Core model, but performed better with an R2 of 50% in Girona city. Independent LUR models for the first and second measurements at the subset of sites with repetitions had R2's of about 47%. When the mean of the two measurements was used R2 improved to 72%. ConclusionsLUR models for UFP were developed, based on a highly cost-effective short-term monitoring campaign at a large number of sites, with fair performance. Complementing the approach with further strategies to address sources of temporal variation of UFP is likely to result in improved models as indicated by the good performance of the model based on the subset of sites with one repeated measurement. Our approach is promising for UFP and possibly for other PM components requiring active sampling.

Rivera, Marcela; Basagaña, Xavier; Aguilera, Inmaculada; Agis, David; Bouso, Laura; Foraster, Maria; Medina-Ramón, Mercedes; Pey, Jorge; Künzli, Nino; Hoek, Gerard

2012-07-01

209

Measurements of ultrafine particles from a gas-turbine burning biofuels  

SciTech Connect

Measurements of ultrafine particles have been performed at the exhaust of a low emission microturbine for power generation. This device has been fuelled with liquid fuels, including a commercial diesel oil, a mixture of the diesel oil with a biodiesel and kerosene, and tested under different loads. Primarily attention has been focused on the measurements of the size distribution functions of the particles emitted from the system by using particle differential mobility analysis. A bimodal size distribution function of the particle emitted has been found in all the examined conditions. Burning diesel oil, the first mode of the size distribution function of the combustion-formed particles is centered at around 2-3 nm, whereas the second mode is centered at about 20-30 nm. The increase of the turbine load and the addition of 50% of biodiesel has not caused changes in the shape of size distribution of the particles. A slightly decrease of the amount of particle formed has been found. By using kerosene the amount of emitted particles increases of more than one order of magnitude. Also the shape of the size distribution function changes with the first mode shifted towards larger particles of the order of 8-10 nm but with a lower emission of larger 20-30 nm particles. Overall, in this conditions, the mass concentration of particles is increased respect to the diesel oil operation. Particle sizes measured with the diesel oil have been compared with the results on a diesel engine operated in the same power conditions and with the same fuel. Measurements have showed that the mean sizes of the formed particles do not change in the two combustion systems. However, diesel engine emits a number concentration of particles more than two orders of magnitude higher in the same conditions of power and with the same fuel. By running the engine in more premixed-like conditions, the size distribution function of the particles approaches that measured by burning kerosene in the microturbine indicating that the distribution function of the sizes of the emitted particles can be strongly affected by combustion conditions. (author)

Allouis, C.; Beretta, F.; Minutolo, P.; Pagliara, R. [Istituto di Ricerche sulla Combustione, CNR, Piazzale V. Tecchio, 80, 80125 Napoli (Italy); Sirignano, M.; Sgro, L.A.; D'Anna, A. [Dipartimento di Ingegneria Chimica, Universita di Napoli Federico II, Piazzale V. Tecchio, 80, 80125 Napoli (Italy)

2010-04-15

210

Environmentally persistent free radicals amplify ultrafine particle mediated cellular oxidative stress and cytotoxicity  

PubMed Central

Background Combustion generated particulate matter is deposited in the respiratory tract and pose a hazard to the lungs through their potential to cause oxidative stress and inflammation. We have previously shown that combustion of fuels and chlorinated hydrocarbons produce semiquinone-type radicals that are stabilized on particle surfaces (i.e. environmentally persistent free radicals; EPFRs). Because the composition and properties of actual combustion-generated particles are complex, heterogeneous in origin, and vary from day-to-day, we have chosen to use surrogate particle systems. In particular, we have chosen to use the radical of 2-monochlorophenol (MCP230) as the EPFR because we have previously shown that it forms a EPFR on Cu(II)O surfaces and catalyzes formation of PCDD/F. To understand the physicochemical properties responsible for the adverse pulmonary effects of combustion by-products, we have exposed human bronchial epithelial cells (BEAS-2B) to MCP230 or the CuO/silica substrate. Our general hypothesis was that the EPFR-containing particle would have greater toxicity than the substrate species. Results Exposure of BEAS-2B cells to our combustion generated particle systems significantly increased reactive oxygen species (ROS) generation and decreased cellular antioxidants resulting in cell death. Resveratrol treatment reversed the decline in cellular glutathione (GSH), glutathione peroxidase (GPx), and superoxide dismutase (SOD) levels for both types of combustion-generated particle systems. Conclusion The enhanced cytotoxicity upon exposure to MCP230 correlated with its ability to generate more cellular oxidative stress and concurrently reduce the antioxidant defenses of the epithelial cells (i.e. reduced GSH, SOD activity, and GPx). The EPFRs in MCP230 also seem to be of greater biological concern due to their ability to induce lipid peroxidation. These results are consistent with the oxidizing nature of the CuO/silica ultrafine particles and the reducing nature and prolonged environmental and biological lifetimes of the EPFRs in MCP230.

Balakrishna, Shrilatha; Lomnicki, Slawo; McAvey, Kevin M; Cole, Richard B; Dellinger, Barry; Cormier, Stephania A

2009-01-01

211

Removal of Ultra-Fine Aerosol Particles From the Atmospheric Boundary Layer During Precipitation  

NASA Astrophysics Data System (ADS)

New aerosol particles are formed in atmospheric environment as a result of the secondary particle production, or homogeneous nucleation of gaseous species. Direct emissions of small particles into atmosphere are related to road traffic, power plants and additional mechanisms involving ion-assisted nucleation. These processes contribute to ultra-fine particle (UFP) presence in atmosphere (defined as particles with diameter less than 100 nm), which can have health effects and can impact cloud properties. UFP formed in the boundary layer (BL) need to grow up to a diameter dp ~ 100 nm to become activated as cloud droplets (CD). The time required to reach dp=100 nm is about 2-3 days for a typical growth rate of 5 nm hr-1, while significant variability was reported from experimental data. If precipitation occurs, most UFP are too small to become CD and some particles are removed by scavenging processes. A model to estimate the UFP wet removal from the BL by rainfall and coagulation is presented. The scavenging coefficient that describes the decay of aerosol mass in various size bins is a function of aerosol size (dp), rainfall rate (R), and BL background aerosol. The model is applied to determine the UFP characteristic removal time during precipitation, due to below-cloud scavenging by falling raindrops, coagulation with background aerosol, mixing in-cloud followed by coagulation with cloud hydrometeors. Results show that during rain events, the 0.5-folding time is t05 ~ 1 hr for R ~ 1 mm hr-1 for newly created particles (dp < 10 nm) and t05 ~ 1 day for larger UFP (dp ~ 10-100 nm). The likelihood of UFP removal at locations with specific precipitation regimes is also illustrated.

Andronache, C.

2004-05-01

212

Formation of bands of ultrafine beryllium particles during rapid solidification of Al-Be alloys: Modeling and direct observations  

SciTech Connect

Rapid solidification of dilute hyper-eutectic and monotectic alloys sometimes produces a dispersion of ultrafine randomly-oriented particles that lie in arrays parallel to the advancing solidification front. The authors characterize this effect in Al-Be where Be-rich particles with diameters on the order of 10 nm form in arrays spaced approximately 25 nm apart, and they present a model of macroscopically steady state but microscopically oscillatory motion of the solidification front to explain this unusual microstructure. The proposed mechanism involves; (i) the build-up of rejected solute in a diffusional boundary layer which slows down the growing crystal matrix, (2) the boundary layer composition entering a metastable liquid miscibility gap, (3) homogeneous nucleation of solute rich liquid droplets in the boundary layer, and crystallization of these droplets, and (4) growth of the matrix past the droplets and its reformation into a planar interface. The size of the Be-rich particles is limited by the beryllium supersaturation in the diffusional boundary layer. A numerical model was developed to investigate this solidification mechanism, and the results of the model are in good agreement with experimental observations of rapidly solidified Al-5 at.% Be.

Elmer, J.W.; Tanner, L.E.; Smith, P.M.; Wall, M.A. (Lawrence Livermore National Lab., CA (United States)); Aziz, M.J. (Harvard Univ., Cambridge, MA (United States). Div. of Applied Sciences)

1994-04-01

213

Development of the electroacoustic dewatering (EAD) process for fine\\/ultrafine coal  

Microsoft Academic Search

Battelle is undertaking engineering development of an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to commercial coal dewatering systems, such as belt filter presses. The Battelle project for demonstrating the potential for commercial application of the EAD process

B. C. Kim; C. L. Criner; H. Wu; R. Menton; N. Senapati; S. P. Chauhan

1990-01-01

214

Development of the Electroacoustic Dewatering (EAD) process for fine\\/ultrafine coal  

Microsoft Academic Search

Battelle, in cooperation with the Electric Power Research Institute (EPRI), CQ, Inc., Ashbrook-Simon-Hartley (ASH), Lewis Corporation, and Professor S. H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaption of synergistic effects of electric and acoustic fields to commercial

B. F. Jirjis; N. Senapati; R. Menton; P. Hsieh; S. P. Chauhan; S. H. Chiang; Y. S. Cheng

1990-01-01

215

Development of the electroacoustic dewatering (EAD) process for fine\\/ultrafine coal. Final report  

Microsoft Academic Search

Battelle (Columbus, Ohio) undertook development of its electro-acoustic (EAD) process to demonstrate its commercial potential for continuous dewatering of fine and ultrafine coals. The pilot plant and laboratory results, provided in this report, show that a commercial-size EAD machine is expected to economically achieve the dewatering targets for -100 mesh and -325 mesh coals. The EAD process utilizes a synergistic

S. P. Chauhan; B. C. Kim; R. Menton; N. Senapati; C. L. Criner; B. Jirjis; H. S. Muralidhara; Y. L. Chou; H. Wu; P. Hsieh; H. R. Johnson; R. Eason; S. M. Chiang; Y. S. Cheng; D. Kehoe

1991-01-01

216

Development of the electroacoustic dewatering (EAD) process for fine\\/ultrafine coal  

Microsoft Academic Search

Battelle, in cooperation with the Electric Power Research Institute (EPRI) CQ, Inc., Ashbrook-Simon-Hartley (ASH), and Professor S. H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to commercial coal dewatering

B. C. Kim; C. L. Criner; H. Wu; N. Senapati; S. P. Chauhan

1990-01-01

217

Development of the electroacoustic dewatering (EAD) process for fine\\/ultrafine coal  

Microsoft Academic Search

Battelle (Columbus, Ohio) undertook development of its electro-acoustic (EAD) process to demonstrate its commercial potential for continuous dewatering of fine and ultrafine coals. The pilot plant and laboratory results, provided in this report, show that a commercial-size EAD machine is expected to economically achieve the dewatering targets for -100 mesh and -325 mesh coals. The EAD process utilizes a synergistic

S. P. Chauhan; B. C. Kim; R. Menton; N. Senapati; C. L. Criner; B. Jirjis; H. S. Muralidhara; Y. L. Chou; H. Wu; P. Hsieh; H. R. Johnson; R. Eason; S. M. Chiang; Y. S. Cheng; D. Kehoe

1991-01-01

218

GENE PROFILING AND THE ROLE OF COAGULATION FACTORS IN INFLAMMATION SIGNALING IN HUMAN PULMONARY ARTERY ENDOTHELIAL CELLS FOLLOWING ULTRAFINE PARTICLES EXPOUSRE  

EPA Science Inventory

Epidemiologic studies have linked exposures to particulate air pollution and increased cardiovascular mortality and morbidity, however, the mechanisms are not clear. Ultrafine particles within air pollution represent a particular area of concern because the small size fraction o...

219

Unhealthy diet and ultrafine carbon black particles induce senescence and disease associated phenotypic changes.  

PubMed

Diet and pollution are environmental factors known to compromise "healthy aging" of the cardiovascular and respiratory systems. The molecular consequences of this permanent burden in these cells are still unknown. Therefore, this study investigates the impact of unhealthy diet on aging-related signaling pathways of human, primary cardiovascular cells and of airborne particles on lung epithelial and human endothelial cells. Nutrition health reports have shown that the diet in industrialized countries contains more than 100mg/dl low density lipoprotein (LDL) and a high fraction of added sugars, especially fructose. Several studies demonstrated that ultrafine particles can enter the circulation and thus may interact with endothelial cells directly. Both, dietary compounds and pollution derived particles, have been shown to increase the risk for cardiovascular diseases. To simulate an unhealthy diet, we supplemented cell culture media of human primary endothelial cells, smooth muscle cells and cardiomyocytes with LDL and replaced 1/3 of glucose with fructose. We observed hypertrophy in cardiomyocytes, enhanced proliferation in smooth muscle cells and increased senescence, loss of endothelial nitric oxide synthase and increased nuclear FoxO3A in endothelial cells. With respect to pollution we have used ultrafine carbon black particles (ufCB), one of the major constituents of industrial and exhaust emissions, in concentrations our lungs and vessels are constantly exposed to. These concentrations of ufCB increased reactive oxygen species in lung epithelial and vascular endothelial cells and reduced the S-NO content, a marker for NO-bioavailability, in endothelial cells. NO increases activation of Telomerase Reverse Transcriptase (TERT), an enzyme essential for telomere maintenance. TERT is required for proper endothelial cell function and is inactivated by Src kinase under conditions of oxidative stress. ufCB significantly increased Src kinase activation and reduced Telomerase activity in endothelial and lung epithelial cells. As a consequence, ufCB increased senescence of endothelial cells. To investigate whether ufCB show also effects in vivo, we instilled ufCB in concentrations not inducing inflammation into mice. Indeed, eNOS expression was reduced in the abdominal aorta of animals treated with ufCB. Thus, a combination of fructose and LDL in the diet and ufCB, as a major constituent of air pollution, seem to accelerate respiratory and cardiovascular cellular changes, which may compromise "healthy aging" and can lead to cardiovascular and pulmonary diseases. PMID:22507566

Büchner, Nicole; Ale-Agha, Niloofar; Jakob, Sascha; Sydlik, Ulrich; Kunze, Kerstin; Unfried, Klaus; Altschmied, Joachim; Haendeler, Judith

2013-01-01

220

Spatial coherence of nucleation and ultrafine particle concentrations over eastern North America (Invited)  

NASA Astrophysics Data System (ADS)

Particle size distributions from sites in eastern North America imply new particle formation (NPF) is frequently observed, however the absence of an observing network precludes direct estimation of spatial scales of NPF. Inferences regarding the spatial scales of NPF and resulting ultrafine particle (UFP, i.e. sub-100 nm diameter) concentrations are presented based on in situ and remote sensing observations along with simulations conducted with the GLOMAP global chemistry model and the WRF-CHEM regional chemistry model. Analyses of in situ measurements indicate; (i) NPF and UFP concentrations in two long-term data sets (one collected at a site in southern Indiana (MMSF) and the other 1500 km to the northeast, close to Toronto) indicate a high probability of simultaneous NPF and high coherence of UFP concentrations. (ii) The spatial extent of NPF estimated from the temporal duration of events at MMSF and back-trajectories show minimum spatial scales of 340 to 1000 km. (iii) Co-occurrence of NPF along an 80 km transect in southern Indiana but site-to-site variability in UFP concentrations with data from the Indianapolis metropolitan area differing substantially from two non-urban locations. The implied regional scale NPF and relatively high spatial correlation of UFP concentrations are used in part to justify development of a physically-consistent, but statistically-based, proxy for UFP concentrations where the predictors are spatially averaged remote sensing observations. The proxy is built on data from MMSF and includes predictors known to control NPF; Aerosol Optical Depth and Ångstrom exponent from MODIS (as proxies for the condensational sink), and ultraviolet radiation flux and SO2 concentrations from the Ozone Monitoring Instrument, and NH3 concentrations from Tropospheric Emission Spectrometer as indicators of ternary nucleation. The model is applied on a grid of 100x100 km across the whole of eastern North America and the resulting UFP concentrations are cross-compared with output from GLOMAP. The results indicate: (i) Consistent with in situ observations, there is evidence that UFP concentrations, and by association NPF events, are relatively coherent across large spatial scales over eastern North America. (ii) Consistent with in situ observations, NPF intensity peaks during spring and summer. (iii) Satellite-derived estimates of UFP concentrations exhibit a high degree of coherence with GLOMAP in terms of seasonality and spatial patterns. But there is a systematic positive bias in the proxy estimates that may be due to differences in the nucleation mechanism applied, background concentrations associated with primary emissions and/or errors in the condensation and coagulation sinks. To evaluate the spatial variability (i) in UFP concentrations at scales below those represented in the satellite proxy and/or GLOMAP and (ii) of UFP that can be attributed to causes not linked to NPF, we are conducting simulations at 12 km with WRF-CHEM. Initial results suggest a substantial fraction of the non-NPF-related variability in near-surface total UFP concentrations on scales below 100x100 km can be attributed to variations in Aitken mode primary emissions and/or boundary layer dynamics determined by land-use patterns.

Pryor, S. C.; Crippa, P.

2013-12-01

221

Alterations in welding process voltage affect the generation of ultrafine particles, fume composition, and pulmonary toxicity.  

PubMed

The goal was to determine if increasing welding voltage changes the physico-chemical properties of the fume and influences lung responses. Rats inhaled 40 mg/m³ (3 h/day × 3 days) of stainless steel (SS) welding fume generated at a standard voltage setting of 25 V (regular SS) or at a higher voltage (high voltage SS) of 30 V. Particle morphology, size and composition were characterized. Bronchoalveolar lavage was performed at different times after exposures to assess lung injury. Fumes collected from either of the welding conditions appeared as chain-like agglomerates of nanometer-sized primary particles. High voltage SS welding produced a greater number of ultrafine-sized particles. Fume generated by high voltage SS welding was higher in manganese. Pulmonary toxicity was more substantial and persisted longer after exposure to the regular SS fume. In summary, a modest raise in welding voltage affected fume size and elemental composition and altered the temporal lung toxicity profile. PMID:21281223

Antonini, James M; Keane, Michael; Chen, Bean T; Stone, Samuel; Roberts, Jenny R; Schwegler-Berry, Diane; Andrews, Ronnee N; Frazer, David G; Sriram, Krishnan

2011-12-01

222

Ultrafine particles formed by heating droplets of simulated ash containing metals  

SciTech Connect

Coal and biomass combustion and waste incineration produce inorganic aerosol, whose ultrafine fraction is hypothesized to be generated mainly by metal vaporization and subsequent nucleation and growth in a high-temperature atmosphere. To investigate this mechanism, we investigated nanoparticle inception and early growth processes at high temperature by spraying monodisperse droplets of simulated ash containing metals in the centerline of a laboratory ethylene/air laminar premixed flame at stoichiometric conditions. Particles were collected by thermophoresis on mica substrates for atomic force microscopy dimensional and morphological analysis. Chemical nature, volume fraction, and mean diameter of particles were evaluated by in situ UV-Vis broadband light absorption and laser light-scattering measurements. We also measured size distribution of material sampled from the flame without dilution using differential mobility analysis and scanning electron microscopy. Energy dispersive X-ray spectroscopy provided further information on the chemical composition of particles deposited on substrates. Size distributions showed that the flame-generated aerosol have a high number concentration, are mostly smaller than 10 nm, and persist far downstream of the droplet injection point. Preliminary results showed that the coagulation rate of those nanoparticles is much slower than their collision rate, which implies that their lifetime may be long and may represent a severe problem for environmental pollution.

Carbone, F.; Barone, A.; Pagliara, R.; Beretta, F.; D'Anna, A.; D'Alessio, A. [University of Naples Federico II, Naples (Italy)

2008-12-15

223

Characterization of decay and emission rates of ultrafine particles in indoor ice rink.  

PubMed

The purposes of this study were to determine indoor ultrafine particle (UFP, diameter <100 nm) levels in ice rinks and to characterize UFP decay and emission rates. All 15 public ice rinks in Seoul were investigated for UFP and carbon monoxide (CO) concentrations. Three ice rinks did not show peaks in UFP concentrations, and one ice rink used two resurfacers simultaneously. High peaks of UFP and CO concentrations were observed when the resurfacer was operated. The average air change rate in the 11 ice rinks was 0.21 ± 0.13/h. The average decay rates of UFP number concentrations measured by the P-Trak and DiSCmini were 0.54 ± 0.21/h and 0.85 ± 0.34/h, respectively. The average decay rate of UFP surface area concentration was 0.33 ± 0.15/h. The average emission rates of UFP number concentrations measured by P-Trak and DiSCmini were 1.2 × 10(14) ± 6.5 × 10(13) particles/min and 3.3 × 10(14) ± 2.4 × 10(14) particles/min, respectively. The average emission rate of UFP surface area concentration was 3.1 × 10(11) ± 2.0 × 10(11) ?m(2)/min. UFP emission rate was associated with resurfacer age. DiSCmini measured higher decay and emission rates than P-Trak due to their different measuring mechanisms and size ranges. PMID:23176435

Kim, J; Lee, K

2013-08-01

224

Ultrafine particles pollution in urban coastal air due to ship emissions  

NASA Astrophysics Data System (ADS)

Two years of experimental data (2008-2009) of particle number (?2.5 nm diameter) and black carbon concentrations and of gaseous pollutants recorded in the ambient air of a coastal city were analysed in order to assess the impact of ship emissions on the ultrafine particles (UFPs, diameter <100 nm) concentrations in urban ambient air. The observed relationship between particle number and the other air pollutants, allowed segregating the contribution of vehicle exhaust and of ship emissions to the UFP concentrations in the urban ambient air. Vehicle exhausts resulted in high concentrations of UFP, black carbon and NO x during the early morning, when UFPs showed concentrations 15-30 × 10 3 cm -3. Pollutants linked to this source rapidly decreased when inland sea breeze started to flow. However, this airflow resulted in inland transport of ship plumes (emitted in the harbour and in the sea) into the city and in high concentrations of SO 2, NO x and UFP from mid morning to the evening. In this context, UFPs showed concentrations 35-50 × 10 3 cm -3, being the 65-70% of these linked to ship emissions mostly related to SO 2 (gas phase precursor). UFPs pollution is a matter of concern due to adverse effects on human health. Up to the date, most of studies on urban air quality and UFPs have focused on vehicle exhaust emissions. This study shows how inland transport of ship plumes due to sea breeze blowing results in UFPs pollution in coastal cities.

González, Yenny; Rodríguez, Sergio; Guerra García, Juan Carlos; Trujillo, Juan Luis; García, Rosa

2011-09-01

225

Ultrafine Angelica gigas Powder Normalizes Ovarian Hormone Levels and Has Antiosteoporosis Properties in Ovariectomized Rats: Particle Size Effect  

PubMed Central

Abstract The root of Angelica gigas (Korean angelica) is traditionally used to treat women's ailments that are caused by an impairment of menstrual blood flow and cycle irregularities. This study evaluated the effect particle size of Korean angelica powder on its efficacy for treating estrogen-related symptoms of menopause. Initially, Korean angelica roots were pulverized into ultrafine powder, and orally administered to the rats at a concentration of 500?mg/kg body weight for 8 weeks. The effects of Korean angelica powder particle size on extraction yield, contents of bioactive compounds (decursin and decursinol angelate), levels of serum ovarian hormones (estradiol and progesterone), reproductive hormones (luteinizing hormone and follicle-stimulating hormone), and experimental osteoporosis parameters (mineral density, strength, and histological features) were determined. A significant increase (fivefold) in the contents of decursin and decursinol angelate in the extract of the ultrafine Korean angelica powder was observed compared to coarse Korean angelica powder. Rats were divided into sham-operated or ovariectomized (OVX) groups that were fed coarse (CRS) or ultrafine (UF) ground Korean angelica root. The serum levels of estradiol in the OVX_UF group were 19.2% and 54.1% higher than that of OVX_CRS group. Serum bone-alkaline phosphatase/total-alkaline phosphatase index in the OVX_UF group was half that of the OVX_CRS group. In addition, less trabecular bone loss and thick cortical areas were observed in rats administered ultrafine powder. Therefore, ultrafine grinding may enhance the bioactivity of herbal medicines and be especially useful when their extracted forms lose bioactivity during processing, storage, and oral intake.

Choi, Kyeong-Ok; Lee, Inae; Paik, Sae-Yeol-Rim; Kim, Dong Eun; Lim, Jung Dae; Kang, Wie-Soo; Ko, Sanghoon

2012-01-01

226

Assessment of atmospheric ultrafine carbon particle-induced human health risk based on surface area dosimetry  

NASA Astrophysics Data System (ADS)

Evidence shows a strong correlation between human mortality/morbidity and atmospheric ultrafine carbon particle (UFCP with aerodynamic diameter <18 nm). Theoretical and experimental studies have attempted to use mass concentration/dose as exposure dosimetry to construct the dose-response relationships. Yet little attention has been given to the problem of using surface area dosimetry in UFCP-related risk assessment. We introduced an integrated risk assessment framework based on surface area dosimetry to estimate the adverse health potential risk exposed to atmospheric UFCP. We used the neutrophil cells elevation effect as adverse health effect endpoint. We reanalyzed the published data of UFCP particle diameter ( dp) and associated specific surface area (SSA) to reconstruct their relationship through log-linear regression method. Our results show that smaller particle size ( dp < 51 nm) demonstrated steep slope (ln SSA = 11.0-2.03 ln dp), whereas larger particle size ( dp > 51 nm) was found close to the theoretical relationship (ln SSA = 8.65-1.20 ln dp). We applied the modeled relationships to estimate the surface area doses of human inhaled particles in specific scenarios or subgroups. Our findings show that Adult and Youth subgroups in northern Taiwan region posed the highest potential risk, indicating that the median 10% exceedance risks are 39.6 (95%CI: 36.4-42.9) fold compared to control based on neutrophil cells elevation effect. The result provides a preliminary aspect for discussing the human health adverse effect exposed to atmospheric UFCP for specific groups based on particle surface area dosimetry.

Chio, Chia-Pin; Liao, Chung-Min

227

The structure and optical properties of silicon ultrafine particles deposited by the gas-evaporation technique with a supersonic jet nozzle  

Microsoft Academic Search

The structure and properties of silicon (Si) ultrafine particles deposited on Si or SiO2 substrates at 300 K by the gas-evaporation technique with a supersonic jet nozzle were studied. The technique is designed to deposit Si ultrafine particles at the supersonic speed, resulting from the differential pressure between the Si evaporation and the Si deposition chamber. The size of Si

Hiroshi Ono; Shinji Nozaki; Hiroshi Morisaki

1997-01-01

228

Simulation of NO x and ultrafine particles in a street canyon in Stockholm, Sweden  

NASA Astrophysics Data System (ADS)

A computational fluid dynamic (CFD) model has been used to assess the concentrations of NO x and particle number in a street canyon in Stockholm with a high traffic volume. Comparisons of a simulated 11-week long time series of NO x with measurements (both sides of the street, urban background excluded) show good agreement, especially if emissions are distributed to be three times higher along the side of the street where the traffic is uphill, as compared to the downhill side. The simulation of number concentrations of inert particles indicates a similar asymmetry in emissions. A month-long measurement of particle size distribution (7-450 nm) at street level indicates that the ratio of nucleation size mode particle (7-20 nm) to total particle number (7-450 nm) is decreasing for increased particle surface area. Given the strong dominance of the locally generated particles over the urban background, this is interpreted as a local change in the size distribution. The results of a monodisperse aerosol dynamic model, coupled to the CFD model that simulates also the turbulence generated by vehicle movements, show that coagulation and deposition may reduce total particle inside the canyon with approximately 30% during low wind speeds. Most of the removal occurs shortly after emission, before the particles reach the leeward curb-side. Losses between the leeward curb-side and other locations in the street, e.g. roof levels, is estimated to be smaller, less than 10%. Coagulation is the dominating removal process under low wind speed conditions and deposition for higher wind speeds, the summed removal being smaller for high wind velocities. Deposition is enhanced over the road surface due to the velocities generated by vehicle movements. Although coagulation and deposition removal is most effective on the smallest ultrafine particles, this effect is not sufficient to explain the observed change in size distribution. It is suggested that also the formation of particles in the exhaust plumes is influenced by a larger particle surface area in the ambient air.

Gidhagen, L.; Johansson, C.; Langner, J.; Olivares, G.

229

Ultrafine particles are not major carriers of carcinogenic PAHs and their genotoxicity in size-segregated aerosols.  

PubMed

Some studies suggest that genotoxic effects of combustion-related aerosols are induced by carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) and their derivatives, which are part of the organic fraction of the particulate matter (PM) in ambient air. The proportion of the organic fraction in PM is known to vary with particle size. The ultrafine fraction is hypothesized to be the most important carrier of c-PAHs, since it possesses the highest specific surface area of PM. To test this hypothesis, the distribution of c-PAHs in organic extracts (EOMs) was compared for four size fractions of ambient-air aerosols: coarse (1particles and ultrafine particles (dae<0.17). High-volume aerosol samples were collected consecutively in four localities that differed in the level of environmental pollution. The genotoxicity of EOMs was measured by analysis of DNA adducts induced in an a cellular assay consisting of calf thymus DNA with/without rat liver microsomal S9 fraction coupled with (32)P-postlabelling. The upper accumulation fraction was the major size fraction in all four localities, forming 37-46% of the total PM mass. Per m(3) of sampled air, this fraction also bound the largest amount of c-PAHs. Correspondingly, the upper accumulation fraction induced the highest DNA-adduct levels. Per PM mass itself, the lower accumulation fraction is seen to be the most efficient in binding DNA-reactive organic compounds. Interestingly, the results suggest that the fraction of ultrafine particles of various ambient-air samples is neither a major carrier of c-PAHs, nor a major inducer of their genotoxicity, which is an important finding that is relevant to the toxicity and health effects of ultrafine particles, which are so extensively discussed these days. PMID:23466560

Topinka, Jan; Milcova, Alena; Schmuczerova, Jana; Krouzek, Jiri; Hovorka, Jan

2013-06-14

230

SEPARATION OF FISCHER-TROPSCH WAX PRODUCTS FROM ULTRAFINE IRON CATALYST PARTICLES  

SciTech Connect

In this reporting period, a fundamental filtration study was continued to investigate the separation of Fischer-Tropsch Synthesis (FTS) liquids from iron-based catalyst particles. The overall focus of the program is with slurry-phase FTS in slurry bubble column reactor systems. Hydrocarbon products must be separated from catalyst particles before being removed from the reactor system. An efficient wax product/catalyst separation system is a key factor for optimizing operating costs for iron-based slurry-phase FTS. Previous work has focused on catalyst particle attrition and the formation of ultra-fine iron carbide and/or carbon particles. With the current study, we are investigating how the filtration properties are affected by these chemical and physical changes of the catalyst slurry during activation/synthesis. The shakedown phase of the pilot-scale filtration platform was completed at the end of the last reporting period. A study of various molecular weight waxes was initiated to determine the effect of wax physical properties on the permeation rate without catalyst present. As expected, the permeation flux was inversely proportional to the nominal average molecular weight of the polyethylene wax. Even without catalyst particles present in the filtrate, the filtration membranes experience fouling during an induction period on the order of days on-line. Another long-term filtration test was initiated using a batch of iron catalyst that was previously activated with CO to form iron carbide in a separate continuous stirred tank reactor (CSTR) system. The permeation flux stabilized more rapidly than that experienced with unactivated catalyst tests.

James K. Neathery; Gary Jacobs; Burtron H. Davis

2004-09-30

231

Exposure and Toxicity Assessment of Ultrafine Particles from Nearby Traffic in Urban Air in Seoul, Korea  

PubMed Central

Objectives We investigated the particle mass size distribution and chemical properties of air pollution particulate matter (PM) in the urban area and its capacity to induce cytotoxicity in human bronchial epithelial (BEAS-2B) cells. Methods To characterize the mass size distributions and chemical concentrations associated with urban PM, PM samples were collected by a 10-stage Micro-Orifice Uniform Deposit Impactor close to nearby traffic in an urban area from December 2007 to December 2009. PM samples for in vitro cytotoxicity testing were collected by a mini-volume air sampler with PM10 and PM2.5 inlets. Results The PM size distributions were bi-modal, peaking at 0.18 to 0.32 and 1.8 to 3.2 µm. The mass concentrations of the metals in fine particles (0.1 to 1.8 µm) accounted for 45.6 to 80.4% of the mass concentrations of metals in PM10. The mass proportions of fine particles of the pollutants related to traffic emission, lead (80.4%), cadmium (69.0%), and chromium (63.8%) were higher than those of other metals. Iron was the dominant transition metal in the particles, accounting for 64.3% of the PM10 mass in all the samples. We observed PM concentration-dependent cytotoxic effects on BEAS-2B cells. Conclusions We found that exposure to PM2.5 and PM10 from a nearby traffic area induced significant increases in protein expression of inflammatory cytokines (IL-6 and IL-8). The cell death rate and release of cytokines in response to the PM2.5 treatment were higher than those with PM10. The combined results support the hypothesis that ultrafine particles from vehicular sources can induce inflammatory responses related to environmental respiratory injury.

Yang, Ji-Yeon; Kim, Jin-Yong; Jang, Ji-Young; Lee, Gun-Woo; Kim, Soo-Hwan; Shin, Dong-Chun

2013-01-01

232

Destructive adsorption of chlorinated hydrocarbons on ultrafine (nanoscale) particles of calcium oxide. 2  

SciTech Connect

As a one-step approach to the safe destruction of chlorocarbons, the reaction of carbon tetrachloride with ultrafine particles of calcium oxide to give calcium chloride and carbon dioxide (CCL{sub 4}(g) + 2CaO(s) {r_arrow} CO{sub 2}(g) + 2CaCl{sub 2}(s)) has been studied in detail. Calcium oxide prepared by an aerogel/hypercrytical drying method (AP-CaO) is superior to a conventionally prepared (CP-CaO) sample, and both are vastly superior to commercial CaO (CM-CaO). Optimum temperature for this gas-solid reaction is 450 {degrees}C. The effects of surface -OH, added water, CCl{sub 4} pressure, and a wide range of temperatures are discussed. Conditions for the suppression of byproducts C{sub 2}Cl{sub 4} and Cl{sub 2}CO are presented. Morphological changes in the particles after CCl{sub 4} reaction were studied by atomic force microscopy. A wide range of other techniques have been applied toward complete characterization of the process and products, including FT-IR, pulsed U-tube reaction studies, gravimetric adsorption, X-ray diffraction, and GC-MS. 39 refs., 11 figs., 3 tabs.

Koper, O.; Lagadic, I.; Klabunde, K.J. [Kansas State Univ., Manhattan, KS (United States)] [Kansas State Univ., Manhattan, KS (United States)

1997-03-01

233

Modification of Laminar Flow Ultrafine Condensation Particle Counters for the Enhanced Detection of 1 nm Condensation Nuclei  

Microsoft Academic Search

This paper describes simple modifications to thermally diffusive laminar flow ultrafine condensation particle counters (UCPCs) that allow detection of ?1 nm condensation nuclei with much higher efficiencies than have been previously reported. These non-destructive modifications were applied to a commercial butanol-based UCPC (TSI 3025A) and to a diethylene glycol-based UCPC (UMN DEG-UCPC). Size and charge dependent detection efficiencies using the

Chongai Kuang; Modi Chen; Peter H. McMurry; Jian Wang

2012-01-01

234

Modification of Laminar Flow Ultrafine Condensation Particle Counters for the Enhanced Detection of 1 nm Condensation Nuclei  

Microsoft Academic Search

This paper describes simple modifications to thermally diffusive laminar flow ultrafine condensation particle counters (UCPCs) that allow detection of ?1 nm condensation nuclei with much higher efficiencies than have been previously reported. These non-destructive modifications were applied to a commercial butanol-based UCPC (TSI 3025A) and to a diethylene glycol-based UCPC (UMN DEG-UCPC). Size and charge dependent detection efficiencies using the modified

Chongai Kuang; Modi Chen; Peter H. McMurry; Jian Wang

2011-01-01

235

Coating mechanism of nano-TiO 2 films on the surface of ultra-fine calcined coal kaolin particles  

Microsoft Academic Search

A new type of mineral composite was made by calcined coal kaolin. The interaction mechanism of an inorganic modification reagent\\u000a TiOSO4 with the surface of ultra-fine calcined coal kaolin particles (substrate) was studied by X-ray photoelectron spectroscopy.\\u000a The results show that chemisorption exists in the phase boundary between the modification agent and the substrate surface,\\u000a while physical adsorption occurs on

Hai Lin; Ying-Bo Dong

2011-01-01

236

Growth of ultra-fine cobalt ferrite particles by a sol–gel method and their magnetic properties  

Microsoft Academic Search

Ultra-fine CoFe2O4 particles are fabricated by a sol–gel method and magnetic and structural properties of powders are investigated. Cobalt ferrite powders fired at and above 450 °C have only a single-phase spinel structure and behave ferrimagnetically. Powders annealed at 350 °C have a typical spinel structure and are of the paramagnetic and ferrimagnetic nature, simultaneously. With X-ray diffraction and Mossbauer

Jae-Gwang Lee; Jae Yun Park; Chul Sung Kim

1998-01-01

237

Identification and verification of ultrafine particle affinity zones in urban neighbourhoods: sample design and data pre-processing  

PubMed Central

A methodology is presented and validated through which long-term fixed site air quality measurements are used to characterise and remove temporal signals in sample-based measurements which have good spatial coverage but poor temporal resolution. The work has been carried out specifically to provide a spatial dataset of atmospheric ultrafine particle (UFP < 100 nm) data for ongoing epidemiologic cohort analysis but the method is readily transferable to wider epidemiologic investigations and research into the health effects of other pollutant species.

2009-01-01

238

Concentrations of fine, ultrafine, and black carbon particles in auto-rickshaws in New Delhi, India  

NASA Astrophysics Data System (ADS)

Concentrations of air pollutants from vehicles are elevated along roadways, indicating that human exposure in transportation microenvironments may not be adequately characterized by centrally located monitors. We report results from ˜180 h of real-time measurements of fine particle and black carbon mass concentration (PM 2.5, BC) and ultrafine particle number concentration (PN) inside a common vehicle, the auto-rickshaw, in New Delhi, India. Measured exposure concentrations are much higher in this study (geometric mean for ˜60 trip-averaged concentrations: 190 ?g m -3 PM 2.5, 42 ?g m -3 BC, 280 × 10 3 particles cm -3; GSD ˜1.3 for all three pollutants) than reported for transportation microenvironments in other megacities. In-vehicle concentrations exceeded simultaneously measured ambient levels by 1.5× for PM 2.5, 3.6× for BC, and 8.4× for PN. Short-duration peak concentrations (averaging time: 10 s), attributable to exhaust plumes of nearby vehicles, were greater than 300 ?g m -3 for PM 2.5, 85 ?g m -3 for BC, and 650 × 10 3 particles cm -3 for PN. The incremental increase of within-vehicle concentration above ambient levels—which we attribute to in- and near-roadway emission sources—accounted for 30%, 68% and 86% of time-averaged in-vehicle PM 2.5, BC and PN concentrations, respectively. Based on these results, we estimate that one's exposure during a daily commute by auto-rickshaw in Delhi is as least as large as full-day exposures experienced by urban residents of many high-income countries. This study illuminates an environmental health concern that may be common in many populous, low-income cities.

Apte, Joshua, S.; Kirchstetter, Thomas W.; Reich, Alexander, H.; Deshpande, Shyam J.; Kaushik, Geetanjali; Chel, Arvind; Marshall, Julian D.; Nazaroff, William W.

2011-08-01

239

SEPARATION OF FISCHER-TROPSCH WAX PRODUCTS FROM ULTRAFINE IRON CATALYST PARTICLES  

SciTech Connect

In this reporting period, a fundamental filtration study was continued to investigate the separation of Fischer-Tropsch Synthesis (FTS) liquids from iron-based catalyst particles. The overall focus of the program is with slurry-phase FTS in slurry bubble column reactor systems. Hydrocarbon products must be separated from catalyst particles before being removed from the reactor system. An efficient wax product/catalyst separation system is a key factor for optimizing operating costs for iron-based slurry-phase FTS. Previous work has focused on catalyst particle attrition and the formation of ultra-fine iron carbide and/or carbon particles. With the current study, we are investigating how the filtration properties are affected by these chemical and physical changes of the catalyst slurry during activation/synthesis. In this reporting period, a series of crossflow filtration experiments were initiated to study the effect of olefins and oxygenates on the filtration flux and membrane performance. Iron-based FTS reactor waxes contain a significant amount of oxygenates, depending on the catalyst formulation and operating conditions. Mono-olefins and aliphatic alcohols were doped into an activated iron catalyst slurry (with Polywax) to test their influence on filtration properties. The olefins were varied from 5 to 25 wt% and oxygenates from 6 to 17 wt% to simulate a range of reactor slurries reported in the literature. The addition of an alcohol (1-dodecanol) was found to decrease the permeation rate while the olefin added (1-hexadecene) had no effect on the permeation rate. A passive flux maintenance technique was tested that can temporarily increase the permeate rate for 24 hours.

James K. Neathery; Gary Jacobs; Burtron H. Davis

2005-03-31

240

On-road ultrafine particle concentration in the M5 East road tunnel, Sydney, Australia  

NASA Astrophysics Data System (ADS)

The human health effects following exposure to ultrafine (<100 nm) particles (UFPs) produced by fuel combustion, while not completely understood, are generally regarded as detrimental. Road tunnels have emerged as locations where maximum exposure to these particles may occur for the vehicle occupants using them. This study aimed to quantify and investigate the determinants of UFP concentrations in the 4 km twin-bore (eastbound and westbound) M5 East tunnel in Sydney, Australia. Sampling was undertaken using a condensation particle counter (CPC) mounted in a vehicle traversing both tunnel bores at various times of day from May through July, 2006. Supplementary measurements were conducted in February, 2008. Over three hundred transects of the tunnel were performed, and these were distributed evenly between the bores. Additional comparative measurements were conducted on a mixed route comprising major roads and shorter tunnels, all within Sydney. Individual trip average UFP concentrations in the M5 East tunnel bores ranged from 5.53 × 10 4 p cm -3 to 5.95 × 10 6 p cm -3. Data were sorted by hour of capture, and hourly median trip average (HMA) UFP concentrations ranged from 7.81 × 10 4 p cm -3 to 1.73 × 10 6 p cm -3. Hourly median UFP concentrations measured on the mixed route were between 3.71 × 10 4 p cm -3 and 1.55 × 10 5 p cm -3. Hourly heavy diesel vehicle (HDV) traffic volume was a very good determinant of UFP concentration in the eastbound tunnel bore ( R2 = 0.87), but much less so in the westbound bore ( R2 = 0.26). In both bores, the volume of passenger vehicles (i.e. unleaded gasoline-powered vehicles) was a significantly poorer determinant of particle concentration. When compared with similar studies reported previously, the measurements described here were among the highest recorded concentrations, which further highlights the contribution road tunnels may make to the overall UFP exposure of vehicle occupants.

Knibbs, Luke D.; de Dear, Richard J.; Morawska, Lidia; Mengersen, Kerrie L.

241

Measurements of ultrafine particles and other vehicular pollutants inside school buses in South Texas  

NASA Astrophysics Data System (ADS)

Increasing evidence has demonstrated toxic effects of vehicular emitted ultrafine particles (UFPs, diameter < 100 nm), with the highest human exposure usually occurring on and near roadways. Children are particularly at risk due to immature respiratory systems and faster breathing rates. In this study, children's exposure to in-cabin air pollutants, especially UFPs, was measured inside four diesel-powered school buses. Two 1990 and two 2006 model year diesel-powered school buses were selected to represent the age extremes of school buses in service. Each bus was driven on two routine bus runs to study school children's exposure under different transportation conditions in South Texas. The number concentration and size distribution of UFPs, total particle number concentration, PM 2.5, PM 10, black carbon (BC), CO, and CO 2 levels were monitored inside the buses. The average total particle number concentrations observed inside the school buses ranged from 7.3 × 10 3 to 3.4 × 10 4 particles cm -3, depending on engine age and window position. When the windows were closed, the in-cabin air pollutants were more likely due to the school buses' self-pollution. The 1990 model year school buses demonstrated much higher air pollutant concentrations than the 2006 model year ones. When the windows were open, the majority of in-cabin air pollutants came from the outside roadway environment with similar pollutant levels observed regardless of engine ages. The highest average UFP concentration was observed at a bus transfer station where approximately 27 idling school buses were queued to load or unload students. Starting-up and idling generated higher air pollutant levels than the driving state. Higher in-cabin air pollutant concentrations were observed when more students were on board.

Zhang, Qunfang; Zhu, Yifang

2010-01-01

242

Characterization of ultrafine particle number concentration and new particle formation in an urban environment of Taipei, Taiwan  

NASA Astrophysics Data System (ADS)

An intensive aerosol characterization experiment was performed at the Taipei Aerosol and Radiation Observatory (TARO, 25.02° N, 121.53° E) in the urban area of Taipei, Taiwan, during July 2012. Number concentration and size distribution of aerosol particles were measured continuously, which were accompanied by concurrent measurements of mass concentration of submicron particles, PM1 (d ? 1 ?m), and photolysis rate of ozone, J(O1D). The averaged number concentrations of total (Ntotal), accumulation mode (Nacu), Aitken mode (NAitken), and nucleation mode (Nnuc) particles were 13.9 × 103 cm-3, 1.2 × 103 cm-3, 6.1 × 103 cm-3, and 6.6 × 103 cm-3, respectively. Accordingly, the ultrafine particles (UFPs, d ? 100 nm) accounted for 91% of the total number concentration of particles measured in this study (10 ? d ? 429 nm), indicating the importance of UFPs to the air quality and radiation budget in Taipei and its surrounding areas. An averaged Nnuc / NOx ratio of 192.4 cm-3 ppbv-1 was derived from nighttime measurements, which was suggested to be the characteristic of vehicle emissions that contributed to the "urban background" of nucleation mode particles throughout a day. On the contrary, it was found that the number concentration of nucleation mode particles was independent of NOx and could be elevated up to 10 times of the "urban background" levels during daytime, suggesting a substantial amount of nucleation mode particles produced from photochemical processes. Averages (± 1?) of the diameter growth rate (GR) and formation rate of nucleation mode particles, J10, were 11.9 ± 10.6 nm h-1 and 6.9 ± 3.0 cm-3 s-1, respectively. Consistency in the time series of the nucleation mode particle concentration and the proxy of H2SO4 production, UVB · SO2/CS, for new particle formation (NPF) events suggested that photooxidation of SO2 was likely one of the major mechanisms for the formation of new particles in our study area. Moreover, it was revealed that the particle growth rate correlated exponentially with the photolysis of ozone, implying that the condensable vapors were produced mostly from photooxidation reactions. In addition, this study also revealed that Nnuc exhibited a quadratic relationship with J10. The quadratic relationship was inferred as a result of aerosol dynamics and featured NPF processes in urban areas.

Cheung, H. C.; Chou, C. C.-K.; Huang, W.-R.; Tsai, C.-Y.

2013-09-01

243

Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions. Quarterly technical progress report, April 1, 1991--June 30, 1991  

SciTech Connect

The purpose of this program is to design and fabricate an experimental ultra-fine particle generation system; use this system to generate ultra-fine, iron compound, catalyst particles; and to access the ability of these ultra-fine catalyst particles to improve the performance of the solubilization stage of two-stage, catalytic-catalytic liquefaction processes. The effort applied to this program during this reporting period was devoted to experimental design and fabrication tasks.

Not Available

1991-09-01

244

Exposure to Ultrafine Particles from Ambient Air and Oxidative Stress-Induced DNA Damage  

PubMed Central

Background Particulate matter, especially ultrafine particles (UFPs), may cause health effects through generation of oxidative stress, with resulting damage to DNA and other macromolecules. Objective We investigated oxidative damage to DNA and related repair capacity in peripheral blood mononuclear cells (PBMCs) during controlled exposure to urban air particles with assignment of number concentration (NC) to four size modes with average diameters of 12, 23, 57, and 212 nm. Design Twenty-nine healthy adults participated in a randomized, two-factor cross-over study with or without biking exercise for 180 min and with exposure to particles (NC 6169-15362/cm3) or filtered air (NC 91-542/cm3) for 24 hr. Methods The levels of DNA strand breaks (SBs), oxidized purines as formamidopyrimidine DNA glycolase (FPG) sites, and activity of 7,8-dihydro-8-oxoguanine-DNA glycosylase (OGG1) in PBMCs were measured by the Comet assay. mRNA levels of OGG1, nucleoside diphosphate linked moiety X-type motif 1 (NUDT1), and heme oxygenase-1 (HO1) were determined by real-time reverse transcriptase–polymerase chain reaction. Results Exposure to UFPs for 6 and 24 hr significantly increased the levels of SBs and FPG sites, with a further insignificant increase after physical exercise. The OGG1 activity and expression of OGG1, NUDT1, and HO1 were unaltered. There was a significant dose–response relationship between NC and DNA damage, with the 57-nm mode as the major contributor to effects. Concomitant exposure to ozone, nitrogen oxides, and carbon monoxide had no influence. Conclusion Our results indicate that UFPs, especially the 57-nm soot fraction from vehicle emissions, causes systemic oxidative stress with damage to DNA and no apparent compensatory up-regulation of DNA repair within 24 hr.

Brauner, Elvira Vaclavik; Forchhammer, Lykke; M?ller, Peter; Simonsen, Jacob; Glasius, Marianne; Wahlin, Peter; Raaschou-Nielsen, Ole; Loft, Steffen

2007-01-01

245

Ultrafine particle exposures while walking, cycling, and driving along an urban residential roadway  

NASA Astrophysics Data System (ADS)

Elevated concentrations of ultrafine particles (UFPs, <0.1 ?m), which have been linked to adverse health effects, are commonly found along roadways. This study reports UFP and PM2.5 concentrations and respiratory exposures among four transportation modes on an urban residential street in Santa Monica, California while walking, cycling, and driving with windows open and windows closed (with air recirculation on). Repeated measurements were made for nine days during morning (7:30-9:30), afternoon (12:30-14:30), and evening (17:00-19:00) periods. Median UFP concentrations ranged 1-3 × 104 particles cm-3, were 70% lower in afternoon or evening periods compared to the morning, and were 60% lower when driving with windows closed than open. Median PM2.5 ranged 2-15 ?g m-3, well below the annual National Ambient Air Quality standard of 15 ?g m-3. Respiratory UFP exposure (particles inhaled trip-1) was ˜2 times higher while driving with windows open, ˜15 times higher when cycling, and ˜30 times higher walking, than driving with windows closed. During one evening session with perpendicular rather than parallel wind conditions, absolute UFP concentration was 80% higher, suggesting influence of off-roadway sources. Under parallel wind conditions, a parameter called emissions-weighted traffic volume, used to account for higher and lower emitting vehicles, was correlated with beach-site-subtracted UFP using second-order polynomial model (R2 = 0.61). Based on this model, an 83% on-roadway UFP reduction could be achieved by (1) requiring all trucks to meet California 2007 model-year engine standards, (2) reducing light-duty vehicle flows by 25%, and (3) replacing high-emitting light-duty vehicles (pre 1978) with newer 2010 fleet-average vehicles.

Quiros, David C.; Lee, Eon S.; Wang, Rui; Zhu, Yifang

2013-07-01

246

Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer  

NASA Astrophysics Data System (ADS)

Ultrafine particles (UFP) formed in the boundary layer (BL) by nucleation processes need to grow up to a diameter dp ˜ 100 nm to become activated as cloud droplets (CD). The time required to reach dp = 100 nm is about 2-3 days for a typical growth rate of 5 nm h-1. If precipitation occurs, most UFP are too small to become CD, and some particles are removed by scavenging processes. A model to estimate the UFP wet removal from the BL by rainfall and coagulation is presented. The scavenging coefficient that describes the decay of aerosol mass in various size bins is a function of aerosol size (dp), rainfall rate (R), and BL background aerosol. The model is applied to determine the UFP 0.5-folding time (t05) during rain events and results show that t05 ˜ 1 hour for R ˜ 1 mm h-1 for newly created particles (dp < 10 nm) and t05 ˜ 1 day for larger UFP (dp ˜ 10-100 nm). To infer the likelihood of UFP removal at a given location, the average time interval (?t) between rain events with rainfall rate R = 1 mm h-1 at stations with different precipitation regimes was determined. Results show that on average, UFP are very effectively removed from the BL by below-cloud scavenging in tropical regions (?t ˜ 1 day), removed to a significant extent in eastern U.S. regions (?t ˜ 3 days), and are less likely to be removed in southwest U.S. regions (?t ˜ 6-8 days), where the frequency of dry periods is high and UFP have sufficient time to grow.

Andronache, Constantin

2004-08-01

247

Correlation analysis of noise and ultrafine particle counts in a street canyon.  

PubMed

Ultrafine particles (UFP, diameter<100 nm) are very likely to negatively affect human health, as underlined by some epidemiological studies. Unfortunately, further investigation and monitoring are hindered by the high cost involved in measuring these UFP. Therefore we investigated the possibility to correlate UFP counts with data coming from low-cost sensors, most notably noise sensors. Analyses are based on an experiment where UFP counts, noise levels, traffic counts, nitrogen oxide (NO, NO(2) and their combination NO(x)) concentrations, and meteorological data were collected simultaneously in a street canyon with a traffic intensity of 3200 vehicles/day, over a 3-week period during summer. Previous reports that NO(x) concentrations could be used as a proxy to UFP monitoring were verified in our setup. Traffic intensity or noise level data were found to correlate with UFP to a lesser degree than NO(x) did. This can be explained by the important influence of meteorological conditions (mainly wind and humidity), influencing UFP dynamics. Although correlations remain moderate, sound levels are more correlated to UFP in the 20-30 nm range. The particles in this size range have indeed rather short atmospheric residence times, and are thus more closely short-term traffic-related. Finally, the UFP estimates were significantly improved by grouping data with similar relative humidity and wind conditions. By doing this, we were able to devise noise indicators that correlate moderately with total particle counts, reaching a Spearman correlation of R=0.62. Prediction with noise indicators is even comparable to the more-expensive-to-measure NO(x) for the smallest UFP, showing the potential of using microphones to estimate UFP counts. PMID:21075426

Can, A; Rademaker, M; Van Renterghem, T; Mishra, V; Van Poppel, M; Touhafi, A; Theunis, J; De Baets, B; Botteldooren, D

2011-01-01

248

Ultrafine Particle Scavenging by Rainfall at a Boreal Site: Observations and Model Estimations  

NASA Astrophysics Data System (ADS)

Removal of airborne particles from atmosphere during precipitation events represents a major sink of aerosol. We report estimations of aerosol wet removal rates which are important for pollution studies and for climate numerical models. Scavenging coefficients were determined from six years of ultrafine particle (UFP) observations during rain events at a boreal forest site in Southern Finland. The range of the median scavenging coefficients are comparable with results from similar experiments, for the same rainfall rates. A model of UFP scavenging during rain events is described, based on these processes: (1) UFP below-cloud scavenging by falling raindrops; (2) UFP mixing in-cloud and cloud droplet activation scavenging; and (3) UFP in-cloud collection and in-cloud coagulation with cloud droplets. These results are applicable to predominant stratiform precipitation (Rainfall intensity less than 10 mm/h). Our study suggest that the net loss of UFP near the ground during a rain event is the result of below-cloud scavenging due to aerosol collection by raindrops, mixing, cloud droplet activation and in-cloud scavenging. The importance of each process is determined by the mixing between boundary layer (BL) and cloud elements. If the mixing is reduced, then the below-cloud scavenging caused by raindrop collection, is important. However, for typical mixing during rain event, the in- cloud processes are dominant, and can impact directly the overall UFP scavenging from the BL. The chemical composition and aerosol history of chemical processing can impact the growth factor, possibly affecting the scavenged fraction of those particles that reach supersaturation conditions. The study underlines the complex aerosol-hydrometeor interactions and the role of vertical mixing in the overall aerosol scavenging effect observed in the BL.

Andronache, C.; Gronholm, T.; Laakso, L.; Phillips, V.; Venalainen, A.

2006-05-01

249

Wintertime spatio-temporal variation of ultrafine particles in a Belgian city.  

PubMed

Simultaneous measurements of ultrafine particles (UFPs) were carried out at four sampling locations situated within a 1 km(2) grid area in a Belgian city, Borgerhout (Antwerp). All sampling sites had different orientation and height of buildings and dissimilar levels of anthropogenic activities (mainly traffic volume). The aims were to investigate: (i) the spatio-temporal variation of UFP within the area, (ii) the effect of wind direction with respect to the volume of traffic on UFP levels, and (iii) the spatial representativeness of the official monitoring station situated in the study area. All sampling sites followed similar diurnal patterns of UFP variation, but effects of local traffic emissions were evident. Wind direction also had a profound influence on UFP concentrations at certain sites. The results indicated a clear influence of local weather conditions and the more dominant effect of traffic volumes. Our analysis indicated that the regional air quality monitoring station represented the other sampling sites in the study area reasonably well; temporal patterns were found to be comparable though the absolute average concentrations showed differences of up to 35%. PMID:22705865

Mishra, Vinit K; Kumar, Prashant; Van Poppel, Martine; Bleux, Nico; Frijns, Evelien; Reggente, Matteo; Berghmans, Patrick; Int Panis, Luc; Samson, Roeland

2012-08-01

250

Effect of cabin ventilation rate on ultrafine particle exposure inside automobiles.  

PubMed

We alternately measured on-road and in-vehicle ultrafine (<100 nm) particle (UFP) concentration for 5 passenger vehicles that comprised an age range of 18 years. A range of cabin ventilation settings were assessed during 301 trips through a 4 km road tunnel in Sydney, Australia. Outdoor air flow (ventilation) rates under these settings were quantified on open roads using tracer gas techniques. Significant variability in tunnel trip average median in-cabin/on-road (I/O) UFP ratios was observed (0.08 to approximately 1.0). Based on data spanning all test automobiles and ventilation settings, a positive linear relationship was found between outdoor air flow rate and I/O ratio, with the former accounting for a substantial proportion of variation in the latter (R(2) = 0.81). UFP concentrations recorded in-cabin during tunnel travel were significantly higher than those reported by comparable studies performed on open roadways. A simple mathematical model afforded the ability to predict tunnel trip average in-cabin UFP concentrations with good accuracy. Our data indicate that under certain conditions, in-cabin UFP exposures incurred during tunnel travel may contribute significantly to daily exposure. The UFP exposure of automobile occupants appears strongly related to their choice of ventilation setting and vehicle. PMID:20369882

Knibbs, Luke D; de Dear, Richard J; Morawska, Lidia

2010-05-01

251

Ambient ultrafine particles reduce endothelial nitric oxide production via S-glutathionylation of eNOS  

PubMed Central

Exposure to airborne particulate pollutants is intimately linked to vascular oxidative stress and inflammatory responses with clinical relevance to atherosclerosis. Particulate matter (PM) has been reported to induce endothelial dysfunction and atherosclerosis. Here, we tested whether ambient ultrafine particles (UFP, diameter < 200 nm) modulate eNOS activity in terms of nitric oxide (NO) production via protein S-glutathionylation. Treatment of human aortic endothelial cells (HAEC) with UFP significantly reduced NO production. UFP-mediated reduction in NO production was restored in the presence of JNK inhibitor (SP600125), NADPH oxidase inhibitor (Apocynin), anti-oxidant (N-acetyl cysteine), and superoxide dismutase mimetics (Tempol and MnTMPyP). UFP exposure increased the GSSG/GSH ratio and eNOS S-glutathionylation, whereas over-expression of Glutaredoxin-1 (to inhibit S-glutathionylation) restored UFP-mediated reduction in NO production by nearly 80%. Thus, our findings suggest that eNOS S-glutathionylation is a potential mechanism underlying ambient UFP-induced reduction of NO production.

Du, Yunfeng; Navab, Mohamad; Shen, Melody; Hill, James; Pakbin, Payam; Sioutas, Constantinos; Hsiai, Tzung; Li, Rongsong

2013-01-01

252

Morphology of Nano and Micro Fiber Structures in Ultrafine Particles Filtration  

SciTech Connect

Selected procedures permitting to prepare homogeneous nanofibre structures of the desired morphology by employing a suitable combination of variables during the electrospinning process are presented. A comparison (at the same pressure drop) was made of filtration capabilities of planar polyurethane nanostructures formed exclusively by nanofibres, space polycarbonate nanostructures having bead spacers, structures formed by a combination of polymethyl methacrylate micro- and nanofibres and polypropylene meltblown microstructures, through which ultrafine particles of ammonium sulphate 20-400 nm in size were filtered. The structures studied were described using a new digital image analysis technique based on black and white images obtained by scanning electron microscopy. More voluminous structures modified with distance microspheres and having a greater thickness and mass per square area of the material, i.e. structures possessing better mechanical properties, demanded so much in nanostructures, enable preparation of filters having approximately the same free volume fraction as flat nanofibre filters but an increased effective fibre surface area, changed pore size morphology and, consequently, a higher filter quality.

Kimmer, Dusan; Vincent, Ivo; Fenyk, Jan; Petras, David [SPUR a.s., T. Bati 299, 764 22 Zlin (Czech Republic); Zatloukal, Martin; Sambaer, Wannes [Centre of Polymer Systems, Polymer Centre, Tomas Bata University in Zlin, nam. T. G. Masaryka 5555, 760 01 Zlin (Czech Republic); Zdimal, Vladimir [Institute of Chemical Process Fundamentals of the AS CR, v.v.i., Rozvojova 135, 165 02 Praha 6 (Czech Republic)

2011-07-15

253

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

PubMed

Exposure to atmospheric fine particulate matter (PM(2.5)) is a modifiable risk factor of cardiovascular disease. Ultrafine particles (UFP, diameter <0.1 ?m), a subfraction of PM(2.5), promote vascular oxidative stress and inflammatory responses. Epidemiologic studies suggest that PM exposure promotes vascular calcification. Here, we assessed whether UFP exposure promotes vascular calcification via NF-?B signaling. UFP exposure at 50 ?g/ml increased alkaline phosphatase (ALP) activity by 4.4 ± 0.2-fold on day 3 (n = 3, P < 0.001) and matrix calcification by 3.5 ± 1.7-fold on day 10 (n = 4, P < 0.05) in calcifying vascular cells (CVC), a subpopulation of vascular smooth muscle cells with osteoblastic potential. Treatment of CVC with conditioned media derived from UFP-treated macrophages (UFP-CM) also led to an increase in ALP activities and matrix calcification. Furthermore, both UFP and UFP-CM significantly increased NF-?B activity, and cotreatment with an NF-?B inhibitor, JSH23, attenuated both UFP- and UFP-CM-induced ALP activity and calcification. When low-density lipoprotein receptor-null mice were exposed to UFP at 359.5 ?g/m(3) for 10 wk, NF-?B activation and vascular calcification were detected in the regions of aortic roots compared with control filtered air-exposed mice. These findings suggest that UFP promotes vascular calcification via activating NF-?B signaling. PMID:23242187

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

2013-02-15

254

Ambient ultrafine particles reduce endothelial nitric oxide production via S-glutathionylation of eNOS.  

PubMed

Exposure to airborne particulate pollutants is intimately linked to vascular oxidative stress and inflammatory responses with clinical relevance to atherosclerosis. Particulate matter (PM) has been reported to induce endothelial dysfunction and atherosclerosis. Here, we tested whether ambient ultrafine particles (UFP, diameter <200 nm) modulate eNOS activity in terms of nitric oxide (NO) production via protein S-glutathionylation. Treatment of human aortic endothelial cells (HAEC) with UFP significantly reduced NO production. UFP-mediated reduction in NO production was restored in the presence of JNK inhibitor (SP600125), NADPH oxidase inhibitor (Apocynin), anti-oxidant (N-acetyl cysteine), and superoxide dismutase mimetics (Tempol and MnTMPyP). UFP exposure increased the GSSG/GSH ratio and eNOS S-glutathionylation, whereas over-expression of Glutaredoxin-1 (to inhibit S-glutathionylation) restored UFP-mediated reduction in NO production by nearly 80%. Thus, our findings suggest that eNOS S-glutathionylation is a potential mechanism underlying ambient UFP-induced reduction of NO production. PMID:23751346

Du, Yunfeng; Navab, Mohamad; Shen, Melody; Hill, James; Pakbin, Payam; Sioutas, Constantinos; Hsiai, Tzung K; Li, Rongsong

2013-07-01

255

Personal exposure to ultrafine particles: the influence of time-activity patterns.  

PubMed

Exposure to ultrafine particles (UFPs) is deemed to be a major risk affecting human health. Therefore, airborne particle studies were performed in the recent years to evaluate the most critical micro-environments, as well as identifying the main UFP sources. Nonetheless, in order to properly evaluate the UFP exposure, personal monitoring is required as the only way to relate particle exposure levels to the activities performed and micro-environments visited. To this purpose, in the present work, the results of experimental analysis aimed at showing the effect of the time-activity patterns on UFP personal exposure are reported. In particular, 24 non-smoking couples (12 during winter and summer time, respectively), comprised of a man who worked full-time and a woman who was a homemaker, were analyzed using personal particle counter and GPS monitors. Each couple was investigated for a 48-h period, during which they also filled out a diary reporting the daily activities performed. Time activity patterns, particle number concentration exposure and the related dose received by the participants, in terms of particle alveolar-deposited surface area, were measured. The average exposure to particle number concentration was higher for women during both summer and winter (Summer: women 1.8 × 10(4) part. cm(-3); men 9.2 × 10(3) part. cm(-3); Winter: women 2.9 × 10(4) part. cm(-3); men 1.3 × 10(4) part. cm(-3)), which was likely due to the time spent undertaking cooking activities. Staying indoors after cooking also led to higher alveolar-deposited surface area dose for both women and men during the winter time (9.12 × 10(2) and 6.33 × 10(2) mm(2), respectively), when indoor ventilation was greatly reduced. The effect of cooking activities was also detected in terms of women's dose intensity (dose per unit time), being 8.6 and 6.6 in winter and summer, respectively. On the contrary, the highest dose intensity activity for men was time spent using transportation (2.8 in both winter and summer). PMID:24080417

Buonanno, G; Stabile, L; Morawska, L

2014-01-15

256

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

NASA Astrophysics Data System (ADS)

Vehicular emitted air pollutant concentrations were studied near three types of roadways in Austin, Texas: (1) State Highway 71 (SH-71), a heavily traveled arterial highway dominated by passenger vehicles; (2) Interstate 35 (I-35), a limited access highway north of Austin in Georgetown; and (3) Farm to Market Road 973 (FM-973), a heavily traveled surface roadway dominated by truck traffic. Air pollutants examined include carbon monoxide (CO), oxides of nitrogen (NO x), and carbonyl species in the gas-phase. In the particle phase, ultrafine particle (UFP) concentrations (diameter < 100 nm), fine particulate matter (PM 2.5, diameter < 2.5 ?m) mass and carbon content and several particle-bound organics were examined. All roadways had an upwind stationary sampling location, one or two fixed downwind sample locations and a mobile monitoring platform that characterized pollutant concentrations fall-off with increased distance from the roadways. Data reported in this paper focus on UFP while other pollutants and near-roadway chemical processes are examined in a companion paper. Traffic volume, especially heavy-duty traffic, wind speed, and proximity to the road were found to be the most important factors determining UFP concentrations near the roadways. Since wind directions were not consistent during the sampling periods, distances along wind trajectories from the roadway to the sampling points were used to study the decay characteristics of UFPs. Under perpendicular wind conditions, for all studied roadway types, particle number concentrations increased dramatically moving from the upwind side to the downwind side. The elevated particle number concentrations decay exponentially with increasing distances from the roadway with sharp concentration gradients observed within 100-150 m, similar to previously reported studies. A single exponential decay curve was found to fit the data collected from all three roadways very well under perpendicular wind conditions. No consistent pattern was observed for UFPs under parallel wind conditions. However, regardless of wind conditions, particle concentrations returned to background levels within a few hundred meters of the roadway. Within measured UFP size ranges, smaller particles (6-25 nm) decayed faster than larger ones (100-300 nm). Similar decay rates were observed among UFP number, surface, and volume.

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

257

Comparison Between Different Processing Schedules for the Development of Ultrafine-Grained Dual-Phase Steel  

NASA Astrophysics Data System (ADS)

A comparative study was carried out on the development of ultrafine-grained dual-phase (DP) (ferrite-martensite) structures in a low-carbon microalloyed steel processed using two thermomechanical processing routes, (i) intercritical deformation and (ii) warm-deformation and intercritical annealing. The samples were deformed using Gleeble3500® simulator, maintaining a constant total strain ( ? = 1) and strain rate ( = 1/s). Evolution of microstructure and micro-texture was investigated by SEM, TEM, and EBSD. Ultrafine-grained DP structures could be formed by careful selection of deformation temperature, T def (for intercritical deformation) or annealing temperature, T anneal (for warm-deformation and annealing). Overall, the ferrite grain sizes ranged from 1.5 to 4.0 ?m, and the sizes and fractions of the uniformly distributed fine-martensitic islands ranged from 1.5 to 3.0 ?m and 15 to 45 pct, respectively. Dynamic strain-induced austenite-to-ferrite transformation followed by continuous (dynamic) recrystallization of the ferrite dictated the grain refinement during intercritical deformation, while, continuous (static) recrystallization by pronounced recovery dictated the grain refinement during the warm-deformation and the annealing. Regarding intercritical deformation, the samples cooled to T def indicated finer grain size compared with the samples heated to T def, which are explained in terms of the effects of strain partitioning on the ferrite and the heating during deformation. Alpha-fiber components dominated the texture in all the samples, and the fraction of high-angle boundaries (with >15 deg misorientation) increased with the increasing T def or T anneal, depending on the processing schedule. Fine carbide particles, microalloyed precipitates and austenitic islands played important roles in defining the mechanism of grain refinement that involved retarding conventional ferrite recrystallization and ferrite grain growth. With regard to the intercritical deformation, warm-deformation followed by annealing is a simpler process to control in the rolling mill; however, the need for high-power rolling mill and controlled annealing facility imposes industrial challenges.

Karmakar, Anish; Sivaprasad, S.; Nath, S. K.; Misra, R. D. K.; Chakrabarti, Debalay

2014-05-01

258

The influence of morphology of ultra-fine calcite particles on decomposition kinetics  

Microsoft Academic Search

The decomposition kinetics of reference calcite and three ultra-fine samples with different morphologies are investigated.\\u000a The kinetic parameters and rate equation are obtained according to the methods reported in our previous studies. Compared\\u000a with the reference calcite, a considerable diminution of the activation energy E\\u000a a up to 70–80 kJ mol?1 is observed in the case of three ultra-fine samples.

Y.-L. Ren; X. Wang; M. Shui; R.-S. Li

2008-01-01

259

In situ ultrafine particle sizing by a combination of pulsed laser heatup and particle thermal emission  

Microsoft Academic Search

A new in situ method for particle sizing is described. The aerosol particles are heated up by a laser pulse. Their thermal radiation is detected by a photomultiplier. Numerical analysis of the measured signal based on a solution of the first kind Fredholm integral equation results in the particle size distribution. The method is characterized by measurement time of less

P. Roth; A. V. Filippov

1996-01-01

260

Effect of particle-fiber friction coefficient on ultrafine aerosol particles clogging in nanofiber based filter  

NASA Astrophysics Data System (ADS)

Realistic SEM image based 3D filter model considering transition/free molecular flow regime, Brownian diffusion, aerodynamic slip, particle-fiber and particle-particle interactions together with a novel Euclidian distance map based methodology for the pressure drop calculation has been utilized for a polyurethane nanofiber based filter prepared via electrospinning process in order to more deeply understand the effect of particle-fiber friction coefficient on filter clogging and basic filter characteristics. Based on the performed theoretical analysis, it has been revealed that the increase in the fiber-particle friction coefficient causes, firstly, more weaker particle penetration in the filter, creation of dense top layers and generation of higher pressure drop (surface filtration) in comparison with lower particle-fiber friction coefficient filter for which deeper particle penetration takes place (depth filtration), secondly, higher filtration efficiency, thirdly, higher quality factor and finally, higher quality factor sensitivity to the increased collected particle mass. Moreover, it has been revealed that even if the particle-fiber friction coefficient is different, the cake morphology is very similar.

Sambaer, Wannes; Zatloukal, Martin; Kimmer, Dusan

2013-04-01

261

Ambient ultrafine particles alter lipid metabolism and HDL anti-oxidant capacity in LDLR-null mice.  

PubMed

Exposure to ambient particulate matter (PM) is a risk factor for cardiovascular diseases. The redox-active ultrafine particles (UFPs) promote vascular oxidative stress and inflammatory responses. We hypothesized that UFPs modulated lipid metabolism and anti-oxidant capacity of high density lipoprotein (HDL) with an implication in atherosclerotic lesion size. Fat-fed low density lipoprotein receptor-null (LDLR?/? mice were exposed to filtered air (FA) or UFPs for 10 weeks with or without administering an apolipoprotein A-I mimetic peptide made of D-amino acids, D-4F. LDLR?/? mice exposed to UFPs developed a reduced plasma HDL level (P < 0.01), paraoxonase activity (P < 0.01), and HDL anti-oxidant capacity (P < 0.05); but increased LDL oxidation, free oxidized fatty acids, triglycerides, serum amyloid A (P < 0.05), and tumor necrosis factor ? (P < 0.05), accompanied by a 62% increase in the atherosclerotic lesion ratio of the en face aortic staining and a 220% increase in the cross-sectional lesion area of the aortic sinus (P < 0.001). D-4F administration significantly attenuated these changes. UFP exposure promoted pro-atherogenic lipid metabolism and reduced HDL anti-oxidant capacity in fat-fed LDLR?/? mice, associated with a greater atherosclerotic lesion size compared with FA-exposed animals. D-4F attenuated UFP-mediated pro-atherogenic effects, suggesting the role of lipid oxidation underlying UFP-mediated atherosclerosis. PMID:23564731

Li, Rongsong; Navab, Mohamad; Pakbin, Payam; Ning, Zhi; Navab, Kaveh; Hough, Greg; Morgan, Todd E; Finch, Caleb E; Araujo, Jesus A; Fogelman, Alan M; Sioutas, Constantinos; Hsiai, Tzung

2013-06-01

262

Ambient ultrafine particles alter lipid metabolism and HDL anti-oxidant capacity in LDLR-null mice[S  

PubMed Central

Exposure to ambient particulate matter (PM) is a risk factor for cardiovascular diseases. The redox-active ultrafine particles (UFPs) promote vascular oxidative stress and inflammatory responses. We hypothesized that UFPs modulated lipid metabolism and anti-oxidant capacity of high density lipoprotein (HDL) with an implication in atherosclerotic lesion size. Fat-fed low density lipoprotein receptor-null (LDLR?/?) mice were exposed to filtered air (FA) or UFPs for 10 weeks with or without administering an apolipoprotein A-I mimetic peptide made of D-amino acids, D-4F. LDLR?/? mice exposed to UFPs developed a reduced plasma HDL level (P < 0.01), paraoxonase activity (P < 0.01), and HDL anti-oxidant capacity (P < 0.05); but increased LDL oxidation, free oxidized fatty acids, triglycerides, serum amyloid A (P < 0.05), and tumor necrosis factor ? (P < 0.05), accompanied by a 62% increase in the atherosclerotic lesion ratio of the en face aortic staining and a 220% increase in the cross-sectional lesion area of the aortic sinus (P < 0.001). D-4F administration significantly attenuated these changes. UFP exposure promoted pro-atherogenic lipid metabolism and reduced HDL anti-oxidant capacity in fat-fed LDLR?/? mice, associated with a greater atherosclerotic lesion size compared with FA-exposed animals. D-4F attenuated UFP-mediated pro-atherogenic effects, suggesting the role of lipid oxidation underlying UFP-mediated atherosclerosis.

Li, Rongsong; Navab, Mohamad; Pakbin, Payam; Ning, Zhi; Navab, Kaveh; Hough, Greg; Morgan, Todd E.; Finch, Caleb E.; Araujo, Jesus A.; Fogelman, Alan M.; Sioutas, Constantinos; Hsiai, Tzung

2013-01-01

263

Exposure to fine and ultrafine particles from secondhand smoke in public places before and after the smoking ban, Italy 2005  

PubMed Central

Background A smoking ban in all indoor public places was enforced in Italy on 10 January 2005. Methods We compared indoor air quality before and after the smoking ban by monitoring the indoor concentrations of fine (<2.5??m diameter, PM2.5) and ultrafine particulate matter (<0.1??m diameter, UFP). PM2.5 and ultrafine particles were measured in 40 public places (14 bars, six fast food restaurants, eight restaurants, six game rooms, six pubs) in Rome, before and after the introduction of the law banning smoking (after 3 and 12?months). Measurements were taken using real time particle monitors (DustTRAK Mod. 8520 TSI; Ultra?fine Particles Counter?TRAK Model 8525 TSI). The PM2.5 data were scaled using a correction equation derived from a comparison with the reference method (gravimetric measurement). The study was completed by measuring urinary cotinine, and pre?law and post?law enforcement among non?smoking employees at these establishments Results In the post?law period, PM2.5 decreased significantly from a mean concentration of 119.3??g/m3 to 38.2??g/m3 after 3?months (p<0.005), and then to 43.3??g/m3 a year later (p<0.01). The UFP concentrations also decreased significantly from 76?956 particles/cm3 to 38?079 particles/cm3 (p<0.0001) and then to 51?692 particles/cm3 (p<0.01). Similarly, the concentration of urinary cotinine among non?smoking workers decreased from 17.8?ng/ml to 5.5?ng/ml (p<0.0001) and then to 3.7?ng/ml (p<0.0001). Conclusion The application of the smoking ban led to a considerable reduction in the exposure to indoor fine and ultrafine particles in hospitality venues, confirmed by a contemporaneous reduction of urinary cotinine.

Valente, Pasquale; Forastiere, Francesco; Bacosi, Antonella; Cattani, Giorgio; Carlo, Simonetta Di; Ferri, Monica; Figa-Talamanca, Irene; Marconi, Achille; Paoletti, Luigi; Perucci, Carlo; Zuccaro, Piergiorgio

2007-01-01

264

Development of the electroacoustic dewatering (EAD) process for fine/ultrafine coal  

SciTech Connect

Battelle, in cooperation with the Electric Power Research Institute (EPRI) CQ, Inc., Ashbrook-Simon-Hartley (ASH), and Professor S. H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to commercial coal dewatering systems, such as belt filter presses. The project has the following objectives: To validate the expected technical feasibility and energy conservation/economic benefits of the EAD process as applied to fine ({minus}100 mesh) and ultrafine ({minus}325 mesh) coal; and to obtain data from a continuous, process research unit (PRU) in order to conduct a reliable economic analysis and to design commercial EAD filters as well as to promote adaptation of the process by the coal preparation industry. Progress is reported. 2 figs., 4 tabs.

Kim, B.C.; Criner, C.L.; Wu, H.; Senapati, N.; Chauhan, S.P.

1990-08-10

265

Development of the Electroacoustic Dewatering (EAD) process for fine/ultrafine coal  

SciTech Connect

Battelle, in cooperation with the Electric Power Research Institute (EPRI), CQ, Inc., Ashbrook-Simon-Hartley (ASH), Lewis Corporation, and Professor S. H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaption of synergistic effects of electric and acoustic fields to commercial coal dewatering systems, such as belt filter presses include: validation of the expected technical feasibility and energy conservation/economic benefits of the EAD process as applied to fine (-100 mesh) and ultrafine (-325 mesh) coal; and data acquisition from a continuous, process research unit (PRU) in order to conduct a reliable economic analysis and to design commercial EAD filters as well as to promote adaptation of the process by the coal preparation industry.

Jirjis, B.F.; Senapati, N.; Menton, R.; Hsieh, P.; Chauhan, S.P. (Battelle, Columbus, OH (USA)); Chiang, S.H.; Cheng, Y.S. (Pittsburgh Univ., PA (USA). Dept. of Chemical Engineering)

1990-03-13

266

Development of the electroacoustic dewatering (EAD) process for fine/ultrafine coal  

SciTech Connect

Battelle is undertaking engineering development of an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to commercial coal dewatering systems, such as belt filter presses. The Battelle project for demonstrating the potential for commercial application of the EAD process for coal has the following objectives: to validate the expected technical feasibility and energy conservation/economic benefits of the EAD process as applied to fine ({minus}100 mesh) and ultrafine ({minus}325 mesh) coal; and to obtain data from a continuous, process research unit (PRU) in order to conduct a reliable economic analysis and to design commercial EAD filters as well as to promote adaptation of the process by the coal preparation industry. Progress is discussed. 4 figs.

Kim, B.C.; Criner, C.L.; Wu, H.; Menton, R.; Senapati, N.; Chauhan, S.P.

1990-11-09

267

Ultrafine particle concentrations in the surroundings of an urban area: comparing downwind to upwind conditions using Generalized Additive Models (GAMs).  

PubMed

The aim of this study was to investigate the influence of an urban area on ultrafine particle (UFP) concentration in nearby surrounding areas. We assessed how downwind and upwind conditions affect the UFP concentration at a site placed a few kilometres from the city border. Secondarily, we investigated the relationship among other meteorological factors, temporal variables and UFP. Data were collected for 44 days during 2008 and 2009 at a rural site placed about 3 kilometres from Bologna, in northern Italy. Measurements were performed using a spectrometer (FMPS TSI 3091). The average UFP number concentration was 11?776 (±7836) particles per cm(3). We analysed the effect of wind direction in a multivariate Generalized Additive Model (GAM) adjusted for the principal meteorological parameters and temporal trends. An increase of about 25% in UFP levels was observed when the site was downwind of the urban area, compared with the levels observed when wind blew from rural areas. The size distribution of particles was also affected by the wind direction, showing higher concentration of small size particles when the wind blew from the urban area. The GAM showed a good fit to the data (R(2) = 0.81). Model choice was via Akaike Information Criteria (AIC). The analysis also revealed that an approach based on meteorological data plus temporal trends improved the goodness of the fit of the model. In addition, the findings contribute to evidence on effects of exposure to ultrafine particles on a population living in city surroundings. PMID:24077061

Sartini, Claudio; Zauli Sajani, Stefano; Ricciardelli, Isabella; Delgado-Saborit, Juana Mari; Scotto, Fabiana; Trentini, Arianna; Ferrari, Silvia; Poluzzi, Vanes

2013-10-23

268

Particle Size Analysis—Problems and Possibilities in the Fine and Ultrafine Range  

Microsoft Academic Search

The paper discusses some experiences in the field of particle size analysis and is restricted to the off-line techniques measuring the particle size distributions of solids. A survey concerning the developments of methods and instruments is followed by a representation of some actual problems (sampling procedure, coincidence, distance between particles, and interaction forces).

Claus Bernhardt

2000-01-01

269

Effects of ultrafine diesel exhaust particles on oxidative stress generation and dopamine metabolism in PC-12 cells.  

PubMed

A major constituent of urban air pollution is diesel exhaust, a complex mixture of gases, chemicals, and particles. Recent evidence suggests that exposure to air pollution can increase the risk of a fatal stroke, cause cerebrovascular damage, and induce neuroinflammation and oxidative stress that may trigger neurodegenerative diseases, such as Parkinson's disease. The specific aim of this study was to determine whether ultrafine diesel exhaust particles (DEPs), the particle component of exhaust from diesel engines, can induce oxidative stress and effect dopamine metabolism in PC-12 cells. After 24h exposure to DEPs of 200nm or smaller, cell viability, ROS and nitric oxide (NO2) generation, and levels of dopamine (DA) and its metabolites, (dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA)), were evaluated. Results indicated cell viability was not significantly changed by DEP exposure. However, ROS showed dramatic dose-dependent changes after DEP exposure (2.4 fold increase compared to control at 200?g/mL). NO2 levels were also dose-dependently increased after DEP exposure. Although not in a dose-dependent manner, upon DEP exposure, intracellular DA levels were increased while DOPAC and HVA levels decreased when compared to control. Results suggest that ultrafine DEPs lead to dopamine accumulation in the cytoplasm of PC-12 cells, possibly contributing to ROS formation. Further studies are warranted to elucidate this mechanism. PMID:24705343

Kim, Yong-Dae; Lantz-McPeak, Susan M; Ali, Syed F; Kleinman, Michael T; Choi, Young-Sook; Kim, Heon

2014-05-01

270

TRANSLOCATION AND POTENTIAL NEUROLOGICAL EFFECTS OF FINE AND ULTRAFINE PARTICLES: A CRITICAL UPDATE  

EPA Science Inventory

This proceedings book is a collection of seminars presented in a symposium organized by by Munich's GSF-National Research Center for Environment and Health. Research presented at this symposium indicated inhaled ultrafine particulate matter quickly exits the lungs and target...

271

Ultrafine particles near a major roadway in Raleigh, North Carolina: Downwind attenuation and correlation with traffic-related pollutants  

NASA Astrophysics Data System (ADS)

Ultrafine particles (UFPs, diameter < 100 nm) and co-emitted pollutants from traffic are a potential health threat to nearby populations. During summertime in Raleigh, North Carolina, UFPs were simultaneously measured upwind and downwind of a major roadway using a spatial matrix of five portable industrial hygiene samplers (measuring total counts of 20-1000 nm particles). While the upper sampling range of the portable samplers extends past the defined "ultrafine" upper limit (100 nm), the 20-1000 nm number counts had high correlation (Pearson R = 0.7-0.9) with UFPs (10-70 nm) measured by a co-located research-grade analyzer and thus appear to be driven by the ultrafine range. Highest UFP concentrations were observed during weekday morning work commutes, with levels at 20 m downwind from the road nearly fivefold higher than at an upwind station. A strong downwind spatial gradient was observed, linearly approximated over the first 100 m as an 8% drop in UFP counts per 10 m distance. This result agreed well with UFP spatial gradients estimated from past studies (ranging 5-12% drop per 10 m). Linear regression of other vehicle-related air pollutants measured in near real-time (10-min averages) against UFPs yielded moderate to high correlation with benzene ( R2 = 0.76), toluene ( R2 = 0.49), carbon monoxide ( R2 = 0.74), nitric oxide ( R2 = 0.80), and black carbon ( R2 = 0.65). Overall, these results support the notion that near-road levels of UFPs are heavily influenced by traffic emissions and correlate with other vehicle-produced pollutants, including certain air toxics.

Hagler, G. S. W.; Baldauf, R. W.; Thoma, E. D.; Long, T. R.; Snow, R. F.; Kinsey, J. S.; Oudejans, L.; Gullett, B. K.

272

Characterizing ultrafine particles and other air pollutants in and around school buses.  

PubMed

Increasing evidence has demonstrated toxic effects of ultrafine particles (UFP*, diameter < 100 nm). Children are particularly at risk because of their immature respiratory systems and higher breathing rates per body mass. This study aimed to characterize UFP, PM2.5 (particulate matter < or = 2.5 microm in aerodynamic diameter), and other vehicular-emitted pollutants in and around school buses. Four sub-studies were conducted, including: 1. On-road tests to measure in-cabin air pollutant levels while school buses were being driven; 2. Idling tests to determine the contributions of tailpipe emissions from idling school buses to air pollutant levels in and around school buses under different scenarios; 3. Retrofit tests to evaluate the performance of two retrofit systems, a diesel oxidation catalyst (DOC) muffler and a crankcase filtration system (CFS), on reducing tailpipe emissions and in-cabin air pollutant concentrations under idling and driving conditions; and 4. High efficiency particulate air (HEPA) filter air purifier tests to evaluate the effectiveness of in-cabin filtration. In total, 24 school buses were employed to cover a wide range of school buses commonly used in the United States. Real-time air quality measurements included particle number concentration (PNC), fine and UFP size distribution in the size range 7.6-289 nm, PM2.5 mass concentration, black carbon (BC) concentration, and carbon monoxide (CO) and carbon dioxide (CO2) concentrations. For in-cabin measurements, instruments were placed on a platform secured to the rear seats inside the school buses. For all other tests, a second set of instruments was deployed to simultaneously measure the ambient air pollutant levels. For tailpipe emission measurements, the exhaust was diluted and then measured by instruments identical to those used for the in-cabin measurements. The results show that when driving on roads, in-cabin PNC, fine and UFP size distribution, PM2.5, BC, and CO varied by engine age, window position, driving speed, driving route, and operating conditions. Emissions from idling school buses increased the PNC close to the tailpipe by a factor of up to 26.0. Under some circumstances, tailpipe emissions of idling school buses increased the in-cabin PNC by factors ranging from 1.2 to 5.8 in the 10-30 nm particle size range. Retrofit systems significantly reduced the tailpipe emissions of idling school buses. With both DOC and CFS installed, PNC in tailpipe emissions dropped by 20%-94%. No unequivocal decrease was observed for in-cabin air pollutants after retrofitting. The operation of the air conditioning (AC) unit and the pollutant concentrations in the surrounding ambient air played more important roles than retrofit technologies in determining in-cabin air quality. The use of a HEPA air purifier removed up to 50% of in-cabin particles. Because each sub-study tested only a subset of the 24 school buses, the results should be seen as more exploratory than definitive. PMID:24834688

Zhu, Yifang; Zhang, Qunfang

2014-03-01

273

Combination Effects of Cigarette Smoke Extract and Ambient Ultrafine Particles on Endothelial Cells  

PubMed Central

Previous studies have shown that ambient ultrafine particles with diameters less than 100 nm (UFPs) can pass from the lungs to the circulation because of their very small diameter, and induce lung oxidative stress with a resultant dysfunction of lung endothelial cells. However, no studies have addressed the potential combined effects of UFPs and cigarette smoke on vascular endothelial cells. We hypothesized that co-exposure to UFPs and cigarette smoke extract (CSE) may cause combined effects on activation of endothelial cells and dysfunction of endothelium by oxidative stress through activation of NADPH oxidase. We determined the effects of UFPs with or without CSE on mouse pulmonary microvascular endothelial cells (MPMVEC) obtained from C57BL/6J (wild-type) and gp91phox knock-out mice (gp91phox is one of the key components of NADPH oxidase, one of ROS generators). Our results showed that exposure of MPMVEC from wild-type mice to UFPs or CSE, at a non-toxic dose, induced reactive oxygen species (ROS) generation, increased phosphorylation of p38 and Erk1/2, and up-regulated early growth response -1 (Egr-1) and IL-6 genes. These effects were significantly enhanced when cells were co-exposed to both UFPs and CSE. However, exposure of MPMVEC from gp91phox knock-out mice did not induce the above effects. Furthermore, UFPs- and/or CSE-induced Egr-1 mRNA upregulation was attenuated significantly when cells were pre-treated with p38 specific inhibitor, SB 203580, or MEK1/2 inhibitor, PD98059, and Egr-1 siRNA treatment abolished UFPs- and/or CSE- induced overexpression of IL-6. Our results suggest that UFPs and/or CSE caused activation of NADPH oxidase, resulting in ROS generation that led to activation of MAPKs through induced phosphorylation of p38 and ERK1/2 MAPKs and upregulation of Egr-1. Those effects may further result in endothelial dysfunction through production of cytokines such as IL-6. Our results suggest that co-exposure to UFPs and CSE causes enhanced injury to endothelial cells.

Mo, Yiqun; Wan, Rong; Feng, Lingfang; Chien, Sufan; Tollerud, David J.; Zhang, Qunwei

2011-01-01

274

Development of ultra-fine pitch ball bonding technology  

Microsoft Academic Search

While the environment surrounding wire bonding, i.e., wire, lead frame, wire bonder, and capillary, is being developed more eagerly than ever, wire bonding technology which can better meet the more compact and higher density chips without modifying the existing assembly process is desired. This paper discusses reduction of the diameter of a ball to be formed at the tip of

K. Tatsumi; T. Uno; O. Kitamura; Y. Ohno; T. Katsumata; M. Furusawa

1995-01-01

275

Particle features, oxidation behaviors and magnetic properties of ultrafine particles of Ni-Co alloy prepared by hydrogen plasma metal reaction  

NASA Astrophysics Data System (ADS)

Ni-Co ultrafine particles (UFPs) were prepared by hydrogen plasma metal reaction. Particle characteristics, oxidation, and magnetic properties were investigated and compared. fcc structured Ni-Co UFPs with a sphere shape were prepared over the whole composition range. The particles distribute from 5 to 100 nm in size with an average particle size of about 35 nm. They are thermally stable in air below 433 K, but oxidize quickly at the higher temperatures. The saturation magnetization of the UFPs is lower than that of the corresponding bulk alloy, especially in the Co rich side. Formation of oxide layer on the particle's surface is an important reason for this reduction. Ni-Co UFPs possess large residual magnetization and coercive force above 60% Co. The composition dependence of the saturation magnetization and the coercive force changes remarkably around 60% Co, which implies a large variation in magnetic status around this composition.

Li, X. G.; Murai, T.; Chiba, A.; Takahashi, S.

1999-08-01

276

Response of spontaneously hypertensive rats to inhalation of fine and ultrafine particles from traffic: experimental controlled study  

PubMed Central

Background Many epidemiological studies have shown that mass concentrations of ambient particulate matter (PM) are associated with adverse health effects in the human population. Since PM is still a very crude measure, this experimental study has explored the role of two distinct size fractions: ultrafine (<0.15 ?m) and fine (0.15- 2.5 ?m) PM. In a series of 2-day inhalation studies, spontaneously hypersensitive (SH) rats were exposed to fine, concentrated, ambient PM (fCAP) at a city background location or a combination of ultrafine and fine (u+fCAP) PM at a location dominated by traffic. We examined the effect on inflammation and both pathological and haematological indicators as markers of pulmonary and cardiovascular injury. Exposure concentrations ranged from 399 ?g/m3 to 3613 ?g/m3 for fCAP and from 269?g/m3 to 556 ?g/m3 for u+fCAP. Results Ammonium, nitrate, and sulphate ions accounted for 56 ± 16% of the total fCAP mass concentrations, but only 17 ± 6% of the u+fCAP mass concentrations. Unambiguous particle uptake in alveolar macrophages was only seen after u+fCAP exposures. Neither fCAP nor u+fCAP induced significant changes of cytotoxicity or inflammation in the lung. However, markers of oxidative stress (heme oxygenase-1 and malondialdehyde) were affected by both fCAP and u+fCAP exposure, although not always significantly. Additional analysis revealed heme oxygenase-1 (HO-1) levels that followed a nonmonotonic function with an optimum at around 600 ?g/m3 for fCAP. As a systemic response, exposure to u+fCAP and fCAP resulted in significant decreases of the white blood cell concentrations. Conclusion Minor pulmonary and systemic effects are observed after both fine and ultrafine + fine PM exposure. These effects do not linearly correlate with the CAP mass. A greater component of traffic CAP and/or a larger proportion ultrafine PM does not strengthen the absolute effects.

Kooter, Ingeborg M; Boere, A John F; Fokkens, Paul HB; Leseman, Daan LAC; Dormans, Jan AMA; Cassee, Flemming R

2006-01-01

277

Inhalation of ultrafine carbon particles alters heart rate and heart rate variability in people with type 2 diabetes  

PubMed Central

Background Diabetes may confer an increased risk for the cardiovascular health effects of particulate air pollution, but few human clinical studies of air pollution have included people with diabetes. Ultrafine particles (UFP, ?100 nm in diameter) have been hypothesized to be an important component of particulate air pollution with regard to cardiovascular health effects. Methods 17 never-smoker subjects 30–60 years of age, with stable type 2 diabetes but otherwise healthy, inhaled either filtered air (0–10 particles/cm3) or elemental carbon UFP (~107 particles/cm3, ~50 ug/m3, count median diameter 32 nm) by mouthpiece, for 2 hours at rest, in a double-blind, randomized, crossover study design. A digital 12-lead electrocardiogram (ECG) was recorded continuously for 48 hours, beginning 1 hour prior to exposure. Results Analysis of 5-minute segments of the ECG during quiet rest showed reduced high-frequency heart rate variability with UFP relative to air exposure (p?=?0.014), paralleled by non-significant reductions in time-domain heart rate variability parameters. In the analysis of longer durations of the ECG, we found that UFP exposure increased the heart rate relative to air exposure. During the 21- to 45-hour interval after exposure, the average heart rate increased approximately 8 beats per minute with UFP, compared to 5 beats per minute with air (p?=?0.045). There were no UFP effects on cardiac rhythm or repolarization. Conclusions Inhalation of elemental carbon ultrafine particles alters heart rate and heart rate variability in people with type 2 diabetes. Our findings suggest that effects may occur and persist hours after a single 2-hour exposure.

2014-01-01

278

Preparation of Iron Ultrafine Particles by the Dielectric Breakdown of Fe(CO)5 Using a Transversely Excited Atmospheric CO2 Laser and Their Characteristics  

Microsoft Academic Search

Iron ultrafine particles containing the gamma-phase in a relatively high yield of approx. 50% were prepared by the dielectric breakdown of Fe(CO)5 upon irradiation with a tightly focused laser beam of a transversely excited atmospheric (TEA) CO2 laser. CO is also obtained as a volatile product. The iron particles are fine and isotropic in shape. The particle size is in

Tetsuro Majima; Tesshu Miyahara; Koichi Haneda; Tadahiro Ishii; Michio Takami

1994-01-01

279

Comparison of carcinogen, carbon monoxide, and ultrafine particle emissions from narghile waterpipe and cigarette smoking: Sidestream smoke measurements and assessment of second-hand smoke emission factors  

Microsoft Academic Search

The lack of scientific evidence on the constituents, properties, and health effects of second-hand waterpipe smoke has fueled controversy over whether public smoking bans should include the waterpipe. The purpose of this study was to investigate and compare emissions of ultrafine particles (UFP, <100 nm), carcinogenic polyaromatic hydrocarbons (PAH), volatile aldehydes, and carbon monoxide (CO) for cigarettes and narghile (shisha, hookah)

Nancy Daher; Rawad Saleh; Ezzat Jaroudi; Hiba Sheheitli; Thérèse Badr; Elizabeth Sepetdjian; Mariam Al Rashidi; Najat Saliba; Alan Shihadeh

2010-01-01

280

Size distribution of chemical elements and their source apportionment in ambient coarse, fine, and ultrafine particles in Shanghai urban summer atmosphere.  

PubMed

Ambient coarse particles (diameter 1.8-10 microm), fine particles (diameter 0.1-1.8 microm), and ultrafine particles (diameter < 0.1 microm) in the atmosphere of the city of Shanghai were sampled during the summer of 2008 (from Aug 27 to Sep 08). Microscopic characterization of the particles was investigated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX). Mass concentrations of Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr, and Pb in the size-resolved particles were quantified by using synchrotron radiation X-ray fluorescence (SRXRF). Source apportionment of the chemical elements was analyzed by means of an enrichment factor method. Our results showed that the average mass concentrations of coarse particles, fine particles and ultrafine particles in the summer air were 9.38 +/- 2.18, 8.82 +/- 3.52, and 2.02 +/- 0.41 microg/m3, respectively. The mass percentage of the fine particles accounted for 51.47% in the total mass of PM10, indicating that fine particles are the major component in the Shanghai ambient particles. SEM/EDX results showed that the coarse particles were dominated by minerals, fine particles by soot aggregates and fly ashes, and ultrafine particles by soot particles and unidentified particles. SRXRF results demonstrated that crustal elements were mainly distributed in the coarse particles, while heavy metals were in higher proportions in the fine particles. Source apportionment revealed that Si, K, Ca, Fe, Mn, Rb, and Sr were from crustal sources, and S, Cl, Cu, Zn, As, Se, Br, and Pb from anthropogenic sources. Levels of P, V, Cr, and Ni in particles might be contributed from multi-sources, and need further investigation. PMID:22893966

Lü, Senlin; Zhang, Rui; Yao, Zhenkun; Yi, Fei; Ren, Jingjing; Wu, Minghong; Feng, Man; Wang, Qingyue

2012-01-01

281

Impact of meteorology, traffic characteristics, and distance from roadway on roadside concentrations of ultrafine particulate matter  

EPA Science Inventory

Traffic-laden roadways are major contributors to poor air quality in developed areas, elevating pollutants such as particulate matter (PM) and ozone. Among the numerous air pollutants emitted by vehicles, ultrafine particles (UFPs, diameter ...

282

Mobile platform measurements of ultrafine particles and associated pollutant concentrations on freeways and residential streets in Los Angeles  

NASA Astrophysics Data System (ADS)

Recent health studies have reported that ultrafine particles (UFP) (<0.1 ?m in diameter) may be responsible for some of the adverse health effects broadly attributed to particulate matter. In urban areas, UFP are produced by combustion sources, such as vehicle exhaust, and by secondary formation in the atmosphere. While UFP can be monitored, few studies have explored the impact of local primary sources in urban areas (including mobile sources on freeways) on the temporal and spatial distribution of UFP. This paper describes the integration of multiple monitoring technologies on a mobile platform designed to characterize UFP and associated pollutants, and the application of this platform in a study of UFP number concentrations and size distributions in Los Angeles. Monitoring technologies included two condensation particle counters (TSI Model 3007 and TSI 3022A) and scanning mobility particle sizers for UFP. Real-time measurements made of NO x (by chemiluminesence), black carbon (BC) (by light absorption), particulate matter-phase PAH (by UV ionization), and particle length (by diffusional charging) showed high correlations with UFP numbers, ( r2=0.78 for NO, 0.76 for BC, 0.69 for PAH, and 0.88 for particle length). Average concentrations of UFP and related pollutants varied strongly by location, road type, and truck traffic volumes, suggesting a relationship between these concentrations and truck traffic density.

Westerdahl, Dane; Fruin, Scott; Sax, Todd; Fine, Philip M.; Sioutas, Constantinos

283

Electrode geometry effects on the collection efficiency of submicron and ultra-fine dust particles in spike-plate electrostatic precipitators  

Microsoft Academic Search

The collection efficiency of electrostatic precipitators for the submicron particles ranging from 0.1 to 1 mum and ultrafine particles smaller than 0. lmum is below the requirements of new PM2.5 emission regulations. In this work, numerical and experimental studies were conducted to examine the effect of discharge and collecting electrode geometries on the ion density and electric field profiles and

D. Brocilo; J. Podlinski; J. S. Chang; J. Mizeraczyk; R. D. Findlay

2008-01-01

284

Ultrafine particles as trace catchers for polycyclic aromatic hydrocarbons: the photoelectric aerosol sensor as a tool for in situ sorption and desorption studies  

Microsoft Academic Search

The adsorption, condensation, and desorption behavior of polycyclic aromatic hydrocarbons (PAHs) on the surface of ultrafine particles has been studied. Four different kinds of monodisperse primary particles-carbon, sodium chloride, aluminum oxide, and Aerosil 200-were subjected to PAH adsorption under well-defined conditions. The photoelectric aerosol sensor was used as a sensitive technique for in situ and on-line detection of the degree

Reinhard. Niessner; Peter. Wilbring

1989-01-01

285

Determinants of ultrafine particle exposures in transportation environments: findings of an 8-month survey conducted in Montréal, Canada.  

PubMed

An 8-month sampling campaign was conducted in Montréal, Canada to explore determinants of ultrafine particle (UFP) exposures in transportation environments and to develop models to predict such exposures. Between April and November 2006, UFP (0.02-1 mum) count exposure data were collected for one researcher during 80 morning and evening commutes including a 0.5-km walk, a 3-km bus ride, and a 26-km automobile ride in each direction. Ambient temperature, relative humidity, precipitation, and wind speed/direction data were collected for each transit period and the positions of bus and automobile windows were recorded. Mixing heights were also estimated. Morning UFP exposures were significantly greater than those in the evening, with the highest levels observed in the automobile and the lowest while walking. Wind speed and mixing height were highly correlated, and as a result only wind speed was considered in multivariable models owing to the accessibility of quantitative hourly monitoring data. In these models, each 10 degrees C increase in morning temperature was associated with decreases of 14,560/cm(3) (95% CI=11,111 to 18,020), 8160/cm(3) (95% CI=5060 to 11,260), and 11,310/cm(3) (95% CI=6820 to 15,810) for UFP exposures in walk, bus, and automobile environments, respectively. Likewise, each 10-km/h increase in morning wind speed corresponded to decreases of 8252/cm(3) (95% CI=5130 to 11,360), 6210/cm(3) (95% CI=3420 to 9000), and 6350/cm(3) (95% CI=2440 to 10,260) for UFP exposures in walk, bus, and automobile environments, respectively. Similar trends were observed in the evening hours. In an evaluation of model performance, moderate correlations were observed between measured and predicted UFP exposures on new bus (r=0.65) and automobile (r=0.77) routes. Further research is required to incorporate variables such as traffic density and vehicle ventilation settings into the models presented. PMID:18183044

Weichenthal, Scott; Dufresne, André; Infante-Rivard, Claire; Joseph, Lawrence

2008-11-01

286

Development of the electroacoustic dewatering (EAD) process for fine/ultrafine coal  

SciTech Connect

Battelle (Columbus, Ohio) undertook development of its electro-acoustic (EAD) process to demonstrate its commercial potential for continuous dewatering of fine and ultrafine coals. The pilot plant and laboratory results, provided in this report, show that a commercial-size EAD machine is expected to economically achieve the dewatering targets for {minus}100 mesh and {minus}325 mesh coals. The EAD process utilizes a synergistic combination of electric and acoustic (e.g., ultrasonic) fields in conjunction with conventional mechanical processes, such as belt presses, screw presses, plate and frame filter presses, and vacuum filters. The application of EAD is typically most beneficial after a filter cake is formed utilizing conventional mechanical filtration. (VC)

Chauhan, S.P.; Kim, B.C.; Menton, R.; Senapati, N.; Criner, C.L.; Jirjis, B.; Muralidhara, H.S.; Chou, Y.L.; Wu, H.; Hsieh, P. (Battelle, Columbus, OH (United States)); Johnson, H.R.; Eason, R. (Ashbrook-Simon-Hartley Corp., Houston, TX (United States)); Chiang, S.M.; Cheng, Y.S. (Pittsburgh Univ., PA (United States)); Kehoe, D. (CQ, Inc., Homer City, PA (United States))

1991-10-31

287

Development of the electroacoustic dewatering (EAD) process for fine/ultrafine coal. Final report  

SciTech Connect

Battelle (Columbus, Ohio) undertook development of its electro-acoustic (EAD) process to demonstrate its commercial potential for continuous dewatering of fine and ultrafine coals. The pilot plant and laboratory results, provided in this report, show that a commercial-size EAD machine is expected to economically achieve the dewatering targets for {minus}100 mesh and {minus}325 mesh coals. The EAD process utilizes a synergistic combination of electric and acoustic (e.g., ultrasonic) fields in conjunction with conventional mechanical processes, such as belt presses, screw presses, plate and frame filter presses, and vacuum filters. The application of EAD is typically most beneficial after a filter cake is formed utilizing conventional mechanical filtration. (VC)

Chauhan, S.P.; Kim, B.C.; Menton, R.; Senapati, N.; Criner, C.L.; Jirjis, B.; Muralidhara, H.S.; Chou, Y.L.; Wu, H.; Hsieh, P. [Battelle, Columbus, OH (United States); Johnson, H.R.; Eason, R. [Ashbrook-Simon-Hartley Corp., Houston, TX (United States); Chiang, S.M.; Cheng, Y.S. [Pittsburgh Univ., PA (United States); Kehoe, D. [CQ, Inc., Homer City, PA (United States)

1991-10-31

288

Mineral assemblage anomalies in the slip zone of the 1999 Taiwan Chi-Chi earthquake: Ultrafine particles preserved only in the latest slip zone  

NASA Astrophysics Data System (ADS)

determined mineral assemblages of samples from the Taiwan Chelungpu fault and from milling and heating experiments by using X-ray diffraction and scanning and transmission electron microscopy. The fault system contains three dominant fault zones, the shallowest of which slipped during the 1999 Chi-Chi earthquake. The quartz and clay mineral contents of the primary slip zone were low, and it contained partly amorphous ultrafine particles (several tens of nanometers). Up to 30 weight percent of materials in that zone could not be fit to standard diffraction patterns, whereas nearly 100 weight percent of those in surrounding samples could be. The unfitted component could be attributed to the observed ultrafine particles produced by comminution during the earthquake, because weak diffraction intensities are caused from mineral lattice distortion, granulation, and amorphous coatings. Such particles are a potential proxy for identifying the slip zone of the most recent earthquake along a fault.

Hirono, Tetsuro; Kameda, Jun; Kanda, Hiroki; Tanikawa, Wataru; Ishikawa, Tsuyoshi

2014-05-01

289

A PEMS study of the emissions of gaseous pollutants and ultrafine particles from gasoline- and diesel-fueled vehicles  

NASA Astrophysics Data System (ADS)

On-road emission measurements of gasoline- and diesel-fueled vehicles were conducted by a portable emission measurement system (PEMS) in Shanghai, China. Horiba OBS 2200 and TSI EEPS 3090 were employed to detect gaseous and ultrafine particle emissions during the tests. The driving-based emission factors of gaseous pollutants and particle mass and number were obtained on various road types. The average NOx emission factors of the diesel bus, diesel car, and gasoline car were 8.86, 0.68, and 0.17 g km?1, all of which were in excess of their emission limits. The particle number emission factors were 7.06 × 1014, 6.08 × 1014, and 1.57 × 1014 km?1, generally higher than the results for similar vehicle types reported in the previous studies. The size distributions of the particles emitted from the diesel vehicles were mainly concentrated in the accumulation mode, while those emitted from the gasoline car were mainly distributed in the nucleation mode. Both gaseous and particle emission rates exhibit significant correlations with the change in vehicle speed and power demand. The lowest emission rates for each vehicle type were produced during idling. The highest emission rates for each vehicle type were generally found in high-VSP bins. The particle number emission rates of the gasoline car show the strongest growth trend with increasing VSP and speed. The particle number emission for the gasoline car increased by 3 orders of magnitude from idling to the highest VSP and driving speed conditions. High engine power caused by aggressive driving or heavy loads is the main contributor to high emissions for these vehicles in real-world situations.

Huang, Cheng; Lou, Diming; Hu, Zhiyuan; Feng, Qian; Chen, Yiran; Chen, Changhong; Tan, Piqiang; Yao, Di

2013-10-01

290

Ultra-fine coal characterization  

SciTech Connect

The objectives of this Preparation Program include beneficiation of coal to produce high-quality solid or slurry fuel as alternatives for fuel oil and natural gas. Fine grinding is a necessary prerequisite if physical separations are being considered during such beneficiation since the impurity minerals are very fine-grained and dispersed throughout the coal mass. It is the purpose of this research to study the properties of ultra-fine coal since the behavior of such coal can be different from the behavior of the coarser coal normally encountered during cleaning. Research was divided into six tasks: (1) Sample Collection and Preparation: Suitable samples of the base case coal and eight other representative coals were collected and prepared for the subsequent test work. (2) Chemical and Bulk Property Determinations: Compositions, washabilities, moisture levels, and other coal properties which effect behavior of the fine coal in beneficiation systems were determined for each coal. (3) Mineral Liberation Studies: Liberation of the mineral matter in the coal achieved by fine and ultra-fine grinding and the degree of liberation was determined. (4) Hydrodynamic Study of Particles and Slurries: The deviation of individual fine coal particles from Stoke's Law free-settling behavior was determined. (5) Study of the Surface Properties of Particles: The surface characteristics of fine particles of coal which relate to the effectiveness of beneficiation processes were studied. These included electrical charges in aqueous media (zeta potential) and the wettability of the coals (contact angles), and (6) Predictive Model Development: Empirical predictive equations were developed relating measurable coal characteristics of ultra-fine coal to the response of the coal to froth flotation. Accomplishments are discussed in this report. 55 refs., 53 figs., 64 tabs.

Smit, F.J.; Odekirk, J.R.; Baltich, L.K.

1988-12-01

291

Ultrafine particles of Ulmus davidiana var. japonica induce apoptosis of gastric cancer cells via activation of caspase and endoplasmic reticulum stress.  

PubMed

Small-sized particles are more suitable for targeted delivery and are therapeutically more effective than large-sized particles. In this study, we investigated the anticancer effects of ultrafine particles of Ulmus davidiana var. japonica (ufUJ) on human gastric cancer cell lines SNU-1, SNU-216, and SNU-484. ufUJ induced apoptosis by the proteolytic activation of caspase-9, caspase-6, and caspase-3 and cleavage of poly (ADP-ribose) polymerase. The expression levels of the endoplasmic reticulum stress-related protein BiP markedly increased after ufUJ treatment. BiP knockdown decreased ufUJ-induced cell death. ufUJ-induced apoptosis was inhibited by the caspase-3 inhibitor z-DEVD-fmk, caspase-6 inhibitor z-VEID-fmk, and caspase-9 inhibitor z-LEHD-fmk, and by siRNAs against caspases 3, 6, and 9. Gastric cancer cells did not show anchorage-independent growth in the presence of ufUJ. However, cells treated with caspase inhibitors showed an enhanced colony-forming ability. These findings may be helpful in the prevention of gastric cancer and in the development of functional foods. PMID:24395528

Ahn, Joungjwa; Lee, Jong Suk; Yang, Kyung Mi

2014-06-01

292

RF Netsu Purazuma Ni Yoru SM-CO Kinkokukan Kagobutsu Chobiryushi Gosei No Kenkyu (Study on the Formation of Ultrafine Particles of Sm-Co Intermetallic Compounds Using RF Thermal Plasma).  

National Technical Information Service (NTIS)

Alloy ultrafine particles have been successfully synthesized using RF (radio frequency) thermal plasma only in cases in which all constituent elements have essentially the same physical properties such as melting point and vapor pressure. For the Sm - Co ...

N. Kikukawa M. Sugasawa M. Kobayashi M. Nakamura H. Sakamoto

1993-01-01

293

Composition and magnetic studies of ultrafine Al-substituted Sr hexaferrite particles prepared by citrate sol-gel method  

NASA Astrophysics Data System (ADS)

Ultrafine aluminum-substituted strontium hexaferrite particles have been prepared via citrate sol-gel route. Gels were synthesized with molar ratios [Al 3+]:[Fe 3+] of 0.4:11.6, 1:11, 1.5:10.5 and 2:10 and the ferrite particles were obtained by annealing the gels at 950 °C for 2 and 24 h. Electron energy dispersive X-ray spectroscopy (EDX) verified the presence of Al in the substituted samples. X-ray diffraction (XRD) confirmed the formation of the M-type hexaferrite phase in the samples with some indication of ?-Fe 2O 3. Scanning electron microscope showed that the hexaferrite powder consists hexagonal crystals with average diameter Dav (80-186 nm) that decreases with increasing Al content and increases with increasing annealing time. Magnetic properties were determined using a pulsed-field magnetometer and a vibrating sample magnetometer (VSM). The saturation magnetization at room temperature and the Curie temperature were found to decrease while the coercivity increases with increasing the Al content. The highest coercivity of 10.1 kOe was achieved for the sample with the molar ratio [Al 3+]:[Fe 3+]=2:10 annealed for 24 h. The influences of the particle size, composition and impurity on the magnetic properties were discussed.

Nga, Tran Thi Viet; Duong, Nguyen Phuc; Hien, Than Duc

2012-03-01

294

Study of fine and ultrafine particles for coal cleaning. Fossil energy quarterly report, April 1, 1990June 30, 1990  

Microsoft Academic Search

The primary objective of this research is to identify improved means for predicting the cleanability of fine and ultrafine coal by investigating the phenomena which govern laboratory techniques used to separate coal ground to find and ultrafine sizes for the determination of washability characteristics. This study seeks to identify and quantify factors other than gravity which affect separation, to establish

D. Birlingmair; W. Buttermore; V. Enustun; J. Pollard

1990-01-01

295

Are Ambient Ultrafine, Accumulation Mode, and Fine Particles Associated with Adverse Cardiac Responses in Patients Undergoing Cardiac Rehabilitation?  

PubMed Central

Background: Mechanisms underlying previously reported air pollution and cardiovascular (CV) morbidity associations remain poorly understood. Objectives: We examined associations between markers of pathways thought to underlie these air pollution and CV associations and ambient particle concentrations in postinfarction patients. Methods: We studied 76 patients, from June 2006 to November 2009, who participated in a 10-week cardiac rehabilitation program following a recent (within 3 months) myocardial infarction or unstable angina. Ambient ultrafine particle (UFP; 10–100 nm), accumulation mode particle (AMP; 100–500 nm), and fine particle concentrations (PM2.5; ? 2.5 ?m in aerodynamic diameter) were monitored continuously. Continuous Holter electrocardiogram (ECG) recordings were made before and during supervised, graded, twice weekly, exercise sessions. A venous blood sample was collected and blood pressure was measured before sessions. Results: Using mixed effects models, we observed adverse changes in rMSSD [square root of the mean of the sum of the squared differences between adjacent normal-to-normal (NN) intervals], SDNN (standard deviation of all NN beat intervals), TpTe (time from peak to end of T-wave), heart rate turbulence, systolic and diastolic blood pressures, C-reactive protein, and fibrinogen associated with interquartile range increases in UFP, AMP, and PM2.5 at 1 or more lag times within the previous 5 days. Exposures were not associated with MeanNN, heart-rate–corrected QT interval duration (QTc), deceleration capacity, and white blood cell count was not associated with UFP, AMP, and PM2.5 at any lag time. Conclusions: In cardiac rehabilitation patients, particles were associated with subclinical decreases in parasympathetic modulation, prolongation of late repolarization duration, increased blood pressure, and systemic inflammation. It is possible that such changes could increase the risk of CV events in this susceptible population.

Zareba, Wojciech; Beckett, William; Hopke, Philip K; Oakes, David; Frampton, Mark W; Bisognano, John; Chalupa, David; Bausch, Jan; O'Shea, Karen; Wang, Yungang; Utell, Mark J

2012-01-01

296

Development of ultrafine and pure amorphous and crystalline new materials and their fabrication process -A study on the ultrafine crystalline fibrous materials.  

National Technical Information Service (NTIS)

Rice husk, a unique agricultural by-product produced annually in a considerable amount of quantity, is being considered seriously all over the world as a potential renewable resource for energy and advanced materials. Ultrafine ceramic fiber has been know...

J. C. Lee M. J. Park K. S. Shin D. Y. Lee B. K. Kim

1996-01-01

297

Development of a High-Strength Ultrafine-Grained Ferritic Steel Nanocomposite  

NASA Astrophysics Data System (ADS)

This article describes the microstructural and mechanical properties of 12YWT oxide-dispersion-strengthened (ODS)-ferritic steel nanocomposite. According to the annealing results obtained from X-ray diffraction line profile analysis on mechanically alloyed powders milled for 80 hours, the hot extrusion at 1123 K (850 °C) resulted in a nearly equiaxed ultrafine structure with an ultimate tensile strength of 1470 MPa, yield strength of 1390 MPa, and total elongation of 13 pct at room temperature comparable with high-strength 14YWT ODS steel. Maximum total elongation was found at 973 K (600 °C) where fractography of the tensile specimen showed a fully ductile dimple feature compared with the splitting cracks and very fine dimpled structure observed at room temperature. The presence of very small particles on the wall of dimples at 1073 K (800 °C) with nearly chemical composition of the matrix alloy was attributed to the activation of the boundaries decohesion mechanism as a result of diffusion of solute atoms. The results of Charpy impact test also indicated significant improvement of transition temperature with respect to predecessor 12YWT because of the decreased grain size and more homogeneity of grain size distribution. Hence, this alloy represented a good compromise between the strength and Charpy impact properties.

Rahmanifard, Roohollah; Farhangi, Hasan; Novinrooz, Abdul Javad; Moniri, Samira

2013-02-01

298

Pulmonary delivery of an ultra-fine oxytocin dry powder formulation: potential for treatment of postpartum haemorrhage in developing countries.  

PubMed

Oxytocin is recommended by the World Health Organisation as the most effective uterotonic for the prevention and treatment of postpartum haemorrhage. The requirement for parenteral administration by trained healthcare providers and the need for the drug solution to be maintained under cold-chain storage limit the use of oxytocin in the developing world. In this study, a spray-dried ultrafine formulation of oxytocin was developed with an optimal particle size diameter (1-5 µm) to facilitate aerosolised delivery via the lungs. A powder formulation of oxytocin, using mannitol, glycine and leucine as carriers, was prepared with a volume-based median particle diameter of 1.9 µm. Oxytocin content in the formulation was assayed using high-performance liquid chromatography-mass spectroscopy and was found to be unchanged after spray-drying. Ex vivo contractility studies utilising human and ovine uterine tissue indicated no difference in the bioactivity of oxytocin before and after spray-drying. Uterine electromyographic (EMG) activity in postpartum ewes following pulmonary (in vivo) administration of oxytocin closely mimicked that observed immediately postpartum (0-12 h following normal vaginal delivery of the lamb). In comparison to the intramuscular injection, pulmonary administration of an oxytocin dry powder formulation to postpartum ewes resulted in generally similar EMG responses, however a more rapid onset of uterine EMG activity was observed following pulmonary administration (129 ± 18 s) than intramuscular injection (275 ± 22 s). This is the first study to demonstrate the potential for oxytocin to elicit uterine activity after systemic absorption as an aerosolised powder from the lungs. Aerosolised oxytocin has the potential to provide a stable and easy to administer delivery system for effective prevention and treatment of postpartum haemorrhage in resource-poor settings in the developing world. PMID:24376618

Prankerd, Richard J; Nguyen, Tri-Hung; Ibrahim, Jibriil P; Bischof, Robert J; Nassta, Gemma C; Olerile, Livesey D; Russell, Adrian S; Meiser, Felix; Parkington, Helena C; Coleman, Harold A; Morton, David A V; McIntosh, Michelle P

2013-01-01

299

Pulmonary Delivery of an Ultra-Fine Oxytocin Dry Powder Formulation: Potential for Treatment of Postpartum Haemorrhage in Developing Countries  

PubMed Central

Oxytocin is recommended by the World Health Organisation as the most effective uterotonic for the prevention and treatment of postpartum haemorrhage. The requirement for parenteral administration by trained healthcare providers and the need for the drug solution to be maintained under cold-chain storage limit the use of oxytocin in the developing world. In this study, a spray-dried ultrafine formulation of oxytocin was developed with an optimal particle size diameter (1-5 µm) to facilitate aerosolised delivery via the lungs. A powder formulation of oxytocin, using mannitol, glycine and leucine as carriers, was prepared with a volume-based median particle diameter of 1.9 µm. Oxytocin content in the formulation was assayed using high-performance liquid chromatography-mass spectroscopy and was found to be unchanged after spray-drying. Ex vivo contractility studies utilising human and ovine uterine tissue indicated no difference in the bioactivity of oxytocin before and after spray-drying. Uterine electromyographic (EMG) activity in postpartum ewes following pulmonary (in vivo) administration of oxytocin closely mimicked that observed immediately postpartum (0-12 h following normal vaginal delivery of the lamb). In comparison to the intramuscular injection, pulmonary administration of an oxytocin dry powder formulation to postpartum ewes resulted in generally similar EMG responses, however a more rapid onset of uterine EMG activity was observed following pulmonary administration (129 ± 18 s) than intramuscular injection (275 ± 22 s). This is the first study to demonstrate the potential for oxytocin to elicit uterine activity after systemic absorption as an aerosolised powder from the lungs. Aerosolised oxytocin has the potential to provide a stable and easy to administer delivery system for effective prevention and treatment of postpartum haemorrhage in resource-poor settings in the developing world.

Ibrahim, Jibriil P.; Bischof, Robert J.; Nassta, Gemma C.; Olerile, Livesey D.; Russell, Adrian S.; Meiser, Felix; Parkington, Helena C.; Coleman, Harold A.; Morton, David A. V.; McIntosh, Michelle P.

2013-01-01

300

Exposure to ambient ultrafine particles and urinary 8-hydroxyl-2-deoxyguanosine in children with and without eczema.  

PubMed

Ambient fine and ultrafine particles (UFPs) in urban air are known to contribute to inflammatory and allergic disease. It has been suggested that oxidative stress is an underlying mechanism for the detrimental health effects. The objective of this study was to investigate the short-term effect of ambient UFPs and particulate polycyclic aromatic hydrocarbons (PAHs) on urinary 8-hydroxyl-2-deoxyguanosine (8-OHdG) concentrations in children with and without eczema. Spot urine samples were collected from 84 children twice weekly for 61 days and 8-OHdG content was measured. Significant associations were found between the ambient UFPs and particle bound PAHs and increase in urinary 8-OHdG levels. An inter-quartile range (IQR) increase in the UFP concentration in the 24-h (IQR, 32,300/m(3)) period preceding urine collection was significantly associated with a 5.7% (95% confidence interval [CI], 0.16-1.27%) increase in the urinary 8-OHdG level children with AD. In children without eczema, such short-term effect of previous day UFPs on urinary 8-OHdG was not observed. There were no significant positive associations between the mass fraction of PMs and urinary 8-OHdG. The results suggest that short-term exposure to ambient UFPs plays a critical role in PM induced oxidative stress in children with eczema. PMID:23685365

Song, Sanghwan; Paek, Domyung; Park, Chunghee; Lee, Chulwoo; Lee, Jung-Hyun; Yu, Seung-Do

2013-08-01

301

Measurements of ultrafine particle concentration and size distribution in the urban atmosphere  

Microsoft Academic Search

Particle size distributions were measured at three adjacent sites in Birmingham: a busy roadside (A38); 30 m away from the road and a nearby urban background site. Two scanning mobility particle sizers (SMPS), an electrical low pressure impactor (ELPI), a condensation particle counter and a thermophoretic precipitator were employed to measure and collect particles. Excellent agreement on the number weighted

Ji Ping Shi; A. A. Khan; Roy M. Harrison

1999-01-01

302

Deposition velocities to Sorbus aria, Acer campestre, Populus deltoides X trichocarpa 'Beaupré', Pinus nigra and X Cupressocyparis leylandii for coarse, fine and ultra-fine particles in the urban environment.  

PubMed

Trees are effective in the capture of particles from urban air to the extent that they can significantly improve urban air quality. As a result of their aerodynamic properties conifers, with their smaller leaves and more complex shoot structures, have been shown to capture larger amounts of particle matter than broadleaved trees. This study focuses on the effects of particle size on the deposition velocity of particles (Vg) to five urban tree species (coniferous and broadleaved) measured at two field sites, one urban and polluted and a second more rural. The larger uptake to conifers is confirmed, and for broadleaves and conifers Vg values are shown to be greater for ultra-fine particles (Dp < 1.0 microm) than for fine and coarse particles. This is important since finer particles are more likely to be deposited deep in the alveoli of the human lung causing adverse health effects. The finer particle fraction is also shown to be transported further from the emission source; in this study a busy urban road. In further sets of data the aqueous soluble and insoluble fractions of the ultra-fines were separated, indicating that aqueous insoluble particles made up only a small proportion of the ultra-fines. Much of the ultra-fine fraction is present as aerosol. Chemical analysis of the aqueous soluble fractions of coarse, fine and ultra-fine particles showed the importance of nitrates, chloride and phosphates in all three size categories at the polluted and more rural location. PMID:15327866

Freer-Smith, P H; Beckett, K P; Taylor, Gail

2005-01-01

303

Development of the electroacoustic dewatering (EAD) process for fine/ultrafine coal. Seventh quarterly progress report period ending June 30, 1990.  

National Technical Information Service (NTIS)

Battelle, in cooperation with the Electric Power Research Institute (EPRI) CQ, Inc., Ashbrook-Simon-Hartley (ASH), and Professor S. H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals...

B. C. Kim C. L. Criner H. Wu N. Senapati S. P. Chauhan

1990-01-01

304

Source apportionment of urban fine and ultra-fine particle number concentration in a Western Mediterranean city  

NASA Astrophysics Data System (ADS)

Extensive measurements on particle number concentration and size distribution (13-800 nm), together with detailed chemical composition of PM 2.5 have constituted the main inputs of the database used for a source apportionment analysis. Data were collected at an urban background site in Barcelona, Western Mediterranean. The source identification analysis helped us to distinguish five emission sources (vehicle exhausts, mineral dust, sea spray, industrial source and fuel-oil combustion) and two atmospheric processes (photochemical induced nucleation and regional/urban background particles derived from coagulation and condensation processes). After that, a multilinear regression analysis was applied in order to quantify the contribution of each factor. This study reveals that vehicle exhausts contribute dominantly to the number concentration in all the particle sizes (52-86%), but especially in the range 30-200 nm. This work also points out the importance of the regional and/or urban formed aerosols (secondary inorganic particles) on the total number concentration (around 25% of the total number), with a higher impact on the accumulation mode. The photo-chemically induced nucleation of aerosols only represents a small proportion of the total number as an annual mean (3%), but is very relevant when considering only the nucleation mode (13-20 nm) fraction (23%). The other sources recognized registered sporadic contributions to the total number, coinciding with specific meteorological scenarios. This study discloses the main sources and features affecting and controlling the fine and ultra-fine aerosols in a typical city in the Western Mediterranean coast. Whereas the road traffic appears to be the most important source of sub-micrometric aerosols, other sources may not be negligible under specific meteorological conditions.

Pey, Jorge; Querol, Xavier; Alastuey, Andrés; Rodríguez, Sergio; Putaud, Jean Philippe; Van Dingenen, Rita

305

ASSESSMENT OF REGIONAL DEPOSITION DISTRIBUTION OF INHALED ULTRAFINE, FINE, AND COARSE PARTICLES IN HUMAN LUNGS  

EPA Science Inventory

Deposition site and dose of inhaled particles are key determinants in health risk assessment of particulate pollutants. Previous lung deposition studies have dealt largely with total lung deposition measurement. However, particle deposition does not take place uniformly in the lu...

306

Microstructures developed by compressive deformation of coarse grained and ultrafine grained 5083 Al alloys at 77 K and 298 K  

Microsoft Academic Search

Compression tests were performed on the well-annealed coarse grained (CG) and the near dislocation-free ultrafine grained (UFG) 5083 Al alloys at 298K and 77K. The mechanical behavior of the CG alloy was dominated by the stage III hardening at 298K and the stage II hardening at 77K. The microstructure of the CG alloy compressed at 298K was characterized by well-developed

Kyung-Tae Park; Jun Hwan Park; Yong Shin Lee; Won Jong Nam

2005-01-01

307

Development of the electroacoustic dewatering (EAD) process for fine/ultrafine coal: Third quarterly progress report, (April--June 1989)  

SciTech Connect

Battelle, in cooperation with the Electric Power Research Institute (EPRI), Ashbrook-Simon-Hartley (ASH), Kaiser Engineers (KE), Lewis Corporation, and Professor S.H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to commercial coal dewatering systems, such as belt filter presses. 2 figs., 2 tabs.

Not Available

1989-07-18

308

Formation and Growth of Ultrafine Particles from Methanesulfonic Acid and Amines in a Fast Flow System  

NASA Astrophysics Data System (ADS)

Understanding particle formation and growth is critical for improving our ability to predict visibility reduction, health effects and climate forcing. Methanesulfonic acid (MSA) originating from oxidation of organosulfur compounds is commonly detected in atmospheric particles and has been suggested to be a potentially important gaseous precursor of atmospheric particles. While it is well established that ammonia and amines enhance particle formation from sulfuric acid by orders of magnitude, particle formation from amines and MSA has only recently been demonstrated in a large volume, slow flow tube. In order to further investigate particle formation and growth at much earlier stages, a borosilicate glass fast flow reactor was designed and characterized. This reactor accesses reaction times from 0.5 to 40 s and with multiple inlets, facilitates the study of individual reaction steps. Particle distributions from MSA-amine-water systems are measured using a scanning mobility particle sizer for particles down to 2.5 nm, and filters are used for collection and off-line analysis of gaseous species. The results of comprehensive studies to define the dependence of particle formation on MSA, amine and water concentrations will be reported. These suggest that nucleation in this system is a potential source of particles in the troposphere.

Chen, H.; Ezell, M. J.; Arquero, K. D.; Finlayson-Pitts, B. J.

2013-12-01

309

Influence of soil ageing on bioavailability and ecotoxicity of lead carried by process waste metallic ultrafine particles.  

PubMed

Ultrafine particulate matters enriched with metals are emitted into the atmosphere by industrial activities and can impact terrestrial and aquatic ecosystems. Thus, this study investigated the environmental effects of process particles from a lead-recycling facility after atmospheric deposition on soils and potential run-off to surface waters. The toxicity of lead-enriched PM for ecosystems was investigated on lettuce and bacteria by (i) germination tests, growth assays, lead transfer to plant tissues determination and (ii) Microtox analysis. The influence of ageing and soil properties on metal transfer and ecotoxicity was studied using three different soils and comparing various aged, spiked or historically long-term polluted soils. Finally, lead availability was assessed by 0.01 M CaCl(2) soil extraction. The results showed that process PM have a toxic effect on lettuce seedling growth and on Vibrio fischeri metabolism. Soil-PM interactions significantly influence PM ecotoxicity and bioavailability; the effect is complex and depends on the duration of ageing. Solubilisation or stabilisation processes with metal speciation changes could be involved. Finally, Microtox and phytotoxicity tests are sensitive and complementary tools for studying process PM ecotoxicity. PMID:21868052

Schreck, E; Foucault, Y; Geret, F; Pradere, P; Dumat, C

2011-11-01

310

Densification, Microstructure Evolution and Mechanical Properties of Ultrafine SiC Particle-Dispersed ZrB2 Matrix Composites  

NASA Astrophysics Data System (ADS)

The densification behavior along with the microstructure evolution and some mechanical properties of four ultrafine SiC particle-dispersed ZrB2 matrix composites were studied. The SiC-ZrB2 composites, with a SiC content of 5, 10, 15 and 20 vol%, were densified to near full density by vacuum hot pressing at 1,900°C under a maximum uniaxial pressure of 45 MPa. The presence of SiC greatly improved the sinterability of ZrB2. Grain growth of the diboride matrix was increasingly inhibited for larger amounts of SiC added. Elastic modulus, Poisson ratio, microhardness, flexural strength and fracture toughness were measured at room temperature. Unexpectedly, no obvious effect of the increasing amount of SiC on flexural strength and fracture toughness was found. The former property ranged from 650 to 715 MPa but was actually affected by the exaggerated size of several tenths of micrometers of sintered SiC clusters which acted as dominant critical defects. Also fracture toughness did not receive a marked contribution from the increase of the SiC content. As for the matrix, the prevailing fracture mode of the composites was intragranular, regardless of the SiC content.

Monteverde, Frédéric; Guicciardi, Stefano; Melandri, Cesare; Fabbriche, Daniele Dalle

311

Air Pollution Upregulates Endothelial Cell Procoagulant Activity via Ultrafine Particle-Induced Oxidant Signaling and Tissue Factor Expression.  

PubMed

Air pollution exposure is associated with cardiovascular events triggered by clot formation. Endothelial activation and initiation of coagulation are pathophysiological mechanisms that could link inhaled air pollutants to vascular events. Here we investigated the underlying mechanisms of increased endothelial cell procoagulant activity following exposure to soluble components of ultrafine particles (soluble UF). Human coronary artery endothelial cells (HCAEC) were exposed to soluble UF and assessed for their ability to trigger procoagulant activity in platelet-free plasma. Exposed HCAEC triggered earlier thrombin generation and faster fibrin clot formation, which was abolished by an anti-tissue factor (TF) antibody, indicating TF-dependent effects. Soluble UF exposure increased TF mRNA expression without compensatory increases in key anticoagulant proteins. To identify early events that regulate TF expression, we measured endothelial H2O2 production following soluble UF exposure and identified the enzymatic source. Soluble UF exposure increased endothelial H2O2 production, and antioxidants attenuated UF-induced upregulation of TF, linking the procoagulant responses to reactive oxygen species (ROS) formation. Chemical inhibitors and RNA silencing showed that NOX-4, an important endothelial source of H2O2, was involved in UF-induced upregulation of TF mRNA. These data indicate that soluble UF exposure induces endothelial cell procoagulant activity, which involves de novo TF synthesis, ROS production, and the NOX-4 enzyme. These findings provide mechanistic insight into the adverse cardiovascular effects associated with air pollution exposure. PMID:24752501

Snow, S J; Cheng, W; Wolberg, A S; Carraway, M S

2014-07-01

312

Ambient ultrafine particles provide a strong adjuvant effect in the secondary immune response: implication for traffic-related asthma flares.  

PubMed

We have previously demonstrated that intranasal administration of ambient ultrafine particles (UFP) acts as an adjuvant for primary allergic sensitization to ovalbumin (OVA) in Balb/c mice. It is important to find out whether inhaled UFP exert the same effect on the secondary immune response as a way of explaining asthma flares in already-sensitized individuals due to traffic exposure near a freeway. The objective of this study is to determine whether inhalation exposure to ambient UFP near an urban freeway could enhance the secondary immune response to OVA in already-sensitized mice. Prior OVA-sensitized animals were exposed to concentrated ambient UFP at the time of secondary OVA challenge in our mobile animal laboratory in Los Angeles. OVA-specific antibody production, airway morphometry, allergic airway inflammation, cytokine gene expression, and oxidative stress marker were assessed. As few as five ambient UFP exposures were sufficient to promote the OVA recall immune response, including generating allergic airway inflammation in smaller and more distal airways compared with the adjuvant effect of intranasally instilled UFP on the primary immune response. The secondary immune response was characterized by the T helper 2 and IL-17 cytokine gene expression in the lung. In summary, our results demonstrated that inhalation of prooxidative ambient UFP could effectively boost the secondary immune response to an experimental allergen, indicating that vehicular traffic exposure could exacerbate allergic inflammation in already-sensitized subjects. PMID:20562226

Li, Ning; Harkema, Jack R; Lewandowski, Ryan P; Wang, Meiying; Bramble, Lori A; Gookin, Glenn R; Ning, Zhi; Kleinman, Michael T; Sioutas, Constantinos; Nel, Andre E

2010-09-01

313

Nrf2 Deficiency in Dendritic Cells Enhances the Adjuvant Effect of Ambient Ultrafine Particles on Allergic Sensitization  

PubMed Central

Particulate matter (PM) is an important risk factor for asthma. Generation of oxidative stress by PM is a major mechanism of its health effects. Transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) mediates antioxidant and phase II enzymes and is essential in protecting against oxidative stress and lung inflammation. We have previously shown that ambient ultrafine particles (UFP) could exert a potent adjuvant effect on allergic sensitization to ovalbumin (OVA) in mice. We hypothesized that Nrf2 deficiency in dendritic cells (DC) could enhance the adjuvant potential of UFP on allergic sensitization. We show that the adjuvant effect of intranasally instilled UFP is significantly enhanced in Nrf2 knockout (Nrf2-/-) mice compared with their wild-type (Nrf2+/+) counterparts. Under resting conditions Nrf2-/- DC displayed an intrinsic predilection to a T-helper 2 (Th2)-favoring cytokine profile characterized by low level of IL-12p70 and high level of IL-6 as compared to Nrf2+/+ DC. Adoptive transfer of OVA/UFP-treated Nrf2-/- DC provoked a more severe allergic inflammation in the lung than Nrf2+/+ DC in the same treatment group. We conclude that Nrf2 deficiency in DC may promote a constitutive immune-polarizing cytokine milieu, which we propose may have contributed to the augmented adjuvant effect of UFP on allergic sensitization.

Li, Ning; Wang, Meiying; Barajas, Berenice; Sioutas, Constantinos; Williams, Marc A; Nel, Andre E.

2014-01-01

314

Nrf2 deficiency in dendritic cells enhances the adjuvant effect of ambient ultrafine particles on allergic sensitization.  

PubMed

Particulate matter (PM) is an important risk factor for asthma. Generation of oxidative stress by PM is a major mechanism of its health effects. Transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) mediates antioxidant and phase II enzymes and is essential in protecting against oxidative stress and lung inflammation. We have previously shown that ambient ultrafine particles (UFP) could exert a potent adjuvant effect on allergic sensitization to ovalbumin (OVA) in mice. We hypothesized that Nrf2 deficiency in dendritic cells (DC) could enhance the adjuvant potential of UFP on allergic sensitization. We show that the adjuvant effect of intranasally instilled UFP is significantly enhanced in Nrf2 knockout (Nrf2(-/-)) mice compared with their wild-type (Nrf2(+/+)) counterparts. Under resting conditions, Nrf2(-/-) DC displayed an intrinsic predilection to a T helper 2-favoring cytokine profile characterized by a low level of IL-12p70 and a high level of IL-6 as compared to Nrf2(+/+) DC. Adoptive transfer of OVA/UFP-treated Nrf2(-/-) DC provoked a more severe allergic inflammation in the lung than Nrf2(+/+) DC in the same treatment group. We conclude that Nrf2 deficiency in DC may promote a constitutive immune-polarizing cytokine milieu, which we propose may have contributed to the augmented adjuvant effect of UFP on allergic sensitization. PMID:23595026

Li, Ning; Wang, Meiying; Barajas, Berenice; Sioutas, Constantinos; Williams, Marc A; Nel, Andre E

2013-01-01

315

Size-resolved fine and ultrafine particle composition in Baltimore, Maryland  

NASA Astrophysics Data System (ADS)

The third-generation real-time single-particle mass spectrometer (RSMS-3) was deployed from March to December 2002 in Baltimore, Maryland, as part of the Baltimore Particulate Matter Supersite. The site was located to the east of the downtown area and northwest of many local industrial emission sites. RSMS-3 actively sampled and analyzed over 380,000 individual particles within the 48-770 nm size range. The resulting positive and negative ion spectra for each particle were classified using a neural network algorithm, adaptive resonance theory ART 2-a. A subset of these data, particles analyzed between 1 April and 30 November 2003, is presented here. Over 99% of these particles could be described by 10 major composition types. Ambient number concentrations were determined for each type and correlated with particle size, wind direction, and time of day/year. On the basis of this information, local and regional sources of different composition classes are postulated. Almost 40% of all particles in the Baltimore aerosol are internally mixed, consisting primarily of organic carbon, ammonium nitrate, and ammonium sulfate. Most of these particles are likely derived from regional sources. The remaining particles appear to be derived mainly from local sources and processes and include elemental carbon (almost 30%), ammonium nitrate (over 10%), and various metals (over 20%). The particle composition types found in Baltimore aerosol are compared to previous measurements in Houston and Atlanta.

Tolocka, Michael P.; Lake, Derek A.; Johnston, Murray V.; Wexler, Anthony S.

2005-04-01

316

Evaluation of the Quick Urban and Industrial Complex (QUIC) Modeling System to Predict Ultrafine Particle Levels in an Urban Neighborhood near a Highway  

NASA Astrophysics Data System (ADS)

Exposure to vehicle-generated ultrafine particles (<100 nm; UFP) has been linked to cardiovascular and pulmonary diseases in people living near highways. Due to the high degree of temporal and spatial variation of UFP near highways, models are needed to help predict UFP exposures in near-highway neighborhoods. The goals of this work were to evaluate the ability of QUIC, a random-walk dispersion model, to predict near-highway UFP in an urban neighborhood (<1 km2) for different wind conditions and land-surface detail. QUIC was chosen because it is able to capture a wide variety of land-surface features and has relatively small computational requirements. QUIC models were developed with and without individually-resolved buildings for a neighborhood near Interstate 93 in Somerville (MA, USA), and tested using wind conditions characteristic of the area. Model results were then compared to field data collected with a mobile air pollution monitoring laboratory. Generally good agreement was observed between the model results and field data for winds parallel and perpendicular to the highway. In addition, models that treated neighborhood blocks (i.e., collections of houses surrounded by four intersecting streets) as porous structures through which attenuated wind and UFP could pass performed better than models containing non-porous solid blocks or individual buildings. These results will help inform the development of a predictive UFP model that will be used as part of a cardiovascular health study being conducted in several neighborhoods near I-93 in Somerville.

St. Vincent, A.; Milando, C.; Zhu, S.; Zamore, W.; Brugge, D.; Durant, J.

2010-12-01

317

The observation of multi-axial anisotropy in ultrafine cobalt ferrite particles used in magnetic fluids  

Microsoft Academic Search

It has been shown that nano-sized particles of cobalt ferrite produced by the coprecipitation method for use in magnetic fluids exhibit multiaxial anisotropy, which has not previously been reported for ferrite particles. The value of the magnetic anisotropy constant calculated from measurements of the decay of remanence is similar to that reported for bulk cobalt ferrite.

K. J. Davies; S. Wells; R. V. Upadhyay; S. W. Charles; K. O'Grady; M. El Hilo; T. Meaz; S. Mørup

1995-01-01

318

A Novel Magnetic Separation Technique: Selective Separation of Ultrafine Particles by Magnetophoresis  

Microsoft Academic Search

The selective and specific extraction of species of interest from local environmental and other sample sources are important for scientific research, industrial processes, and environmental applications. A novel process for selective separation of magnetic particles using magnetophoresis is investigated. The principle of this process is that the direction and velocity of particle movement in a magnetic field gradient are determined

F. Coyne Prenger; Laura A. Worl; Michael D. Johnson; Joseph A. Waynert; Robert M. Wingo

2004-01-01

319

Using advanced dispersion models and mobile monitoring to characterize spatial patterns of ultrafine particles in an urban area  

NASA Astrophysics Data System (ADS)

In urban settings with elevated bridges, buildings, and other complex terrain, the relationship between traffic and air pollution can be highly variable and difficult to accurately characterize. Atmospheric dispersion models are often used in this context, but incorporating background concentrations and characterizing emissions at high spatiotemporal resolution is challenging, especially for ultrafine particles (UFPs). Ambient pollutant monitoring can characterize this relationship, especially when using continuous real-time monitoring. However, it is challenging to quantify local source contributions over background or to characterize spatial patterns across a neighborhood. The goal of this study is to evaluate contributions of traffic to neighborhood-scale air pollution using a combination of regression models derived from mobile UFP monitoring observations collected in Brooklyn, NY and outputs from the Quick Urban & Industrial Complex (QUIC) model. QUIC is a dispersion model that can explicitly take into account the three-dimensional shapes of buildings. The monitoring-based regression model characterized concentration gradients from a major elevated roadway, controlling for real-time traffic volume, meteorological variables, and other local sources. QUIC was applied to simulate dispersion from this same major roadway. The relative concentration decreases with distance from the roadway estimated by the monitoring-based regression model after removal of background and by QUIC were similar. Horizontal contour plots with both models demonstrated non-uniform patterns related to building configuration and source heights. We used the best-fit relationship between the monitoring-based regression model after removal of background and the QUIC outputs ( R2 = 0.80) to estimate a UFP emissions factor of 5.7 × 10 14 particles/vehicle-km, which was relatively consistent across key model assumptions. Our joint applications of novel techniques for analyzing mobile monitoring data and the advanced dispersion model QUIC provide insight about source contributions above background levels and spatiotemporal air pollution patterns in urban areas.

Zwack, Leonard M.; Hanna, Steven R.; Spengler, John D.; Levy, Jonathan I.

2011-09-01

320

Indoor/outdoor relationships and mass closure of quasi-ultrafine, accumulation and coarse particles in Barcelona schools  

NASA Astrophysics Data System (ADS)

The mass concentration, chemical composition and sources of quasi-ultrafine (quasi-UFP, PM0.25), accumulation (PM0.25-2.5) and coarse mode (PM2.5-10) particles were determined in indoor and outdoor air at 39 schools in Barcelona (Spain). Quasi-UFP mass concentrations measured (25.6 ?g m-3 outdoors, 23.4 ?g m-3 indoors) are significantly higher than those reported in other studies, and characterised by higher carbonaceous and mineral matter contents and a lower proportion of secondary inorganic ions. Results suggest that quasi-UFPs in Barcelona are affected by local sources in the schools, mainly human activity (e.g. organic material from textiles, etc., contributing 23-46% to total quasi-UFP mass) and playgrounds (in the form of mineral matter, contributing about 9% to the quasi-UFP mass). The particle size distribution patterns of toxicologically relevant metals and major aerosol components was characterised, displaying two modes for most elements and components, and one mode for inorganic salts (ammonium nitrate and sulfate) and elemental carbon (EC). Regarding metals, Ni and Cr were partitioned mainly in quasi-UFPs and could thus be of interest for epidemiological studies, given their high redox properties. Exposure of children to quasi-UFP mass and chemical species was assessed by comparing the concentrations measured at urban background and traffic areas schools. Finally, three main indoor sources across all size fractions were identified by assessing indoor / outdoor ratios (I / O) of PM species used as their tracers: human activity (organic material), cleaning products, paints and plastics (Cl- source), and a metallic mixed source (comprising combinations of Cu, Zn, Co, Cd, Pb, As, V and Cr). Our results support the need to enforce targeted legislation to determine a minimum "safe" distance between major roads and newly built schools to reduce exposure to traffic-derived metals in quasi-UFPs.

Viana, M.; Rivas, I.; Querol, X.; Alastuey, A.; Sunyer, J.; Álvarez-Pedrerol, M.; Bouso, L.; Sioutas, C.

2014-05-01

321

Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions. Quarterly technical progress report, October 1, 1990--December 31, 1990  

SciTech Connect

The program objective is to generate ultra-fine catalyst particles (20 to 400 {Angstrom} in size) and quantify their potential for improving coal dissolution in the solubilization stage of two-stage catalytic-catalytic liquefaction systems. It has been shown that catalyst activity increases significantly with decreasing particle size for particle sizes in the submicron range. Ultra-fine catalyst particle generation will be accomplished using a novel two-step process. First, the severe conditions produced by a supercritical fluid (e.g., supercritical H{sub 2}O or CO{sub 2}) will be used to dissolve suitable catalyst compounds (e.g., Fe{sub 2}O{sub 3}, FeS{sub 2}, and/or Fe(CO){sub 5}). Sulfur containing compounds may be added to the supercritical solvent during catalyst dissolution to enhance the catalytic activity of the resulting ultra-fine, iron based, catalyst particles.

Not Available

1991-08-01

322

Reduction of exposure to ultrafine particles by kitchen exhaust hoods: the effects of exhaust flow rates, particle size, and burner position.  

PubMed

Cooking stoves, both gas and electric, are one of the strongest and most common sources of ultrafine particles (UFP) in homes. UFP have been shown to be associated with adverse health effects such as DNA damage and respiratory and cardiovascular diseases. This study investigates the effectiveness of kitchen exhaust hoods in reducing indoor levels of UFP emitted from a gas stove and oven. Measurements in an unoccupied manufactured house monitored size-resolved UFP (2 nm to 100 nm) concentrations from the gas stove and oven while varying range hood flow rate and burner position. The air change rate in the building was measured continuously based on the decay of a tracer gas (sulfur hexafluoride, SF(6)). The results show that range hood flow rate and burner position (front vs. rear) can have strong effects on the reduction of indoor levels of UFP released from the stove and oven, subsequently reducing occupant exposure to UFP. Higher range hood flow rates are generally more effective for UFP reduction, though the reduction varies with particle diameter. The influence of the range hood exhaust is larger for the back burner than for the front burner. The number-weighted particle reductions for range hood flow rates varying between 100 m(3)/h and 680 m(3)/h range from 31% to 94% for the front burner, from 54% to 98% for the back burner, and from 39% to 96% for the oven. PMID:22750181

Rim, Donghyun; Wallace, Lance; Nabinger, Steven; Persily, Andrew

2012-08-15

323

Ultrafine aerosol formation via ion-mediated nucleation  

Microsoft Academic Search

The role of background ionization in the generation and evolution of ultrafine atmospheric particles is developed through modeling and data analysis. It is found that charged molecular clusters condensing around natural air ions can grow significantly faster than corresponding neutral clusters, and thus preferentially achieve stable, observable sizes. Detailed microphysical simulations of this process seem to explain recent measurements of

Fangqun Yu; Richard P. Turco

2000-01-01

324

Ultrafine cementitious grout  

DOEpatents

An ultrafine cementitious grout in three particle grades containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 30 wt. % to about 70 wt. % Portland cement; from about 30 wt. % to about 70 wt. % pumice containing at least 70% amorphous silicon dioxide; and from 1.2 wt. % to about 5.0 wt. % superplasticizer. The superplasticizer is dispersed in the mixing water prior to the addition of dry grout and the W/CM ratio is about 0.4 to 1/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 .mu.m in width.

Ahrens, Ernst H. (Albuquerque, NM)

1999-01-01

325

Ultrafine cementitious grout  

SciTech Connect

An ultrafine cementitious grout in three particle grades containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 30 wt. % to about 70 wt. % Portland cement; from about 30 wt. % to about 70 wt. % pumice containing at least 70% amorphous silicon dioxide; and from 1.2 wt. % to about 5.0 wt. % superplasticizer. The superplasticizer is dispersed in the mixing water prior to the addition of dry grout and the W/CM ratio is about 0.4 to 1/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 {mu}m in width.

Ahrens, E.H.

1999-10-19

326

Ultrafine cementitious grout  

DOEpatents

An ultrafine cementitious grout having a particle size 90% of which are less than 6 .mu.m in diameter and an average size of about 2.5 .mu.m or less, and preferably 90% of which are less than 5 .mu.m in diameter and an average size of about 2 .mu.m or less containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 40 wt. % to about 50 wt. % Portland cement; from about 50 wt. % to about 60 wt. % pumice containing at least 60% amorphous silicon dioxide; and from 0.1 wt. % to about 1.5 wt. % superplasticizer. The grout is mixed with water in the W/CM ratio of about 0.4-0.6/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 .mu.m in width.

Ahrens, Ernst H. (Albuquerque, NM)

1998-01-01

327

Deposition and retention of ultrafine aerosol particles in the human respiratory system. Normal and pathological cases.  

PubMed

The particle number concentration in ambient air is dominated by nanometer-sized particles. Recent epidemiological studies report an association between the presence of nanoparticles in inhaled air at the workplace and acute morbidity and even mortality in the elderly. A theoretical model of deposition of 20 nm particles in the human alveolus was formulated. Gas flow structure and deposition rate were calculated for alveoli with different elastic properties of lung tissue. Data obtained in the paper show increased convective effects and diffusional rate of deposition of nanoparticles for alveoli with higher stiffness of the alveolar wall. The retention of deposited particles is also higher in these pathological alveoli. Results of our calculations indicate a possibility of existence of a positive loop of coupling in deposition and retention of nanoparticles in the lung with pathological changes. PMID:10927666

Grado?, L; Orlicki, D; Podgórski, A

2000-01-01

328

Bipolar charging of ultrafine particles in the size range below 10 nm  

Microsoft Academic Search

Bipolar diffusion charging of aerosol particles in the size range of 2.3–10 nm was studied experimentally. Charging probability for WOx nanoparticles as a function of particle size was measured using an 241Am aerosol neutralizer for aerosol charging and a tandem DMA (Reischl type) with a VIE-06 Faraday cup electrometer for aerosol measurement. In spite of small deviations in the predictions

G. P. Reischl; J. M. Mäkelä; R. Karch; J. Necid

1996-01-01

329

Elemental composition and sources of fine and ultrafine ambient particles in Erfurt, Germany.  

PubMed

We present the first results of a source apportionment for the urban aerosol in Erfurt, Germany, for the period 1995-1998. The analysis is based on data of particle number concentrations (0.01-2.5 microm; mean 1.8 x 10(4) cm(-3), continuous), the concentration of the ambient gases SO(2), NO, NO(2) and CO (continuous), particle mass less than 2.5 microm (PM(2.5)) and less than 10 microm (PM(10)) (Harvard Impactor sampling, mean PM(2.5) 26.3 micro/m(3), mean PM(10) 38.2 microg/m(3)) and the size fractionated concentrations of 19 elements (impactor sampling 0.05-1.62 microm, PIXE analysis). We determined: (a) the correlations between (i) the 1- and 24-h average concentrations of the gaseous pollutants and the particle number as well as the particle mass concentration and (ii) between the 24-h elemental concentrations; (b) Crustal Enrichment Factors for the PIXE elements using Si as reference element; and (c) the diurnal pattern of the measured pollutants on weekdays and on weekends. The highly correlated PIXE elements Si, Al, Ti and Ca having low enrichment factors were identified as soil elements. The strong correlation of particle number concentrations with NO, which is considered to be typically emitted by traffic, and the striking similarity of their diurnal variation suggest that a sizable fraction of the particle number concentration is associated with emission from vehicles. Besides NO and particle number concentrations other pollutants such as NO(2), CO as well as the elements Zn and Cu were strongly correlated and appear to reflect motor vehicle traffic. Sulfur could be a tracer for coal combustion, however, it was not correlated with any of the quoted elements. Highly correlated elements V and Ni have similar enrichment factors and are considered as tracers for oil combustion. PMID:12670764

Cyrys, J; Stölzel, M; Heinrich, J; Kreyling, W G; Menzel, N; Wittmaack, K; Tuch, T; Wichmann, H-Erich

2003-04-15

330

Development and characterization of metal-diboride-based composites toughened with ultra-fine SiC particulates  

NASA Astrophysics Data System (ADS)

Two metal-diboride-based ceramics containing up to 15 vol%. ultra-fine ?-SiC particulates were developed from commercially available powders. The primary matrix of the composites was ZrB 2 or a mixture of ZrB 2 and HfB 2. With the assistance of 4.5 vol%. ZrN as a sintering aid, both the compositions achieved nearly full density after hot-pressing at 1,900 °C. The microstructure was characterized by fine diboride grains ( ?3 ?m average size) and SiC particles dispersed uniformly. Limited amounts of secondary phases like MO 2 and M(C,N), M=Zr or Zr/Hf, were found. The thermo-mechanical data of both the materials offered a promising combination of properties: about 16 GPa of micro-hardness, 5 MPa? m of fracture toughness and Young's moduli exceeding 470 GPa. The ZrB 2sbnd SiC composite showed values of strength in air of 635 ± 60 and 175 ± 15 MPa at 25 and 1,500 °C, respectively. Likewise, the (ZrB 2 + HfB 2) sbnd SiC composite exhibited values of strength in air of 590 ± 25 and 190 ± 20 MPa at 25 and 1,500 °C, respectively. The composites also displayed good tolerance of conditions of repeated short exposures, 10 minutes each, at 1,700 °C in stagnant air. In such oxidizing conditions, the resistance to oxidation was provided by the formation of a protective silica-based glass coating, the primary oxidation product of SiC. Such a coating encapsulated the specimen coherently, and provided protection to the faces exposed to the hot atmosphere.

Monteverde, Frédéric; Bellosi, Alida

2005-05-01

331

Development of the Electroacoustic Dewatering (EAD) process for fine\\/ultrafine coal  

Microsoft Academic Search

This report describes an advanced process, called Electroacoustic Dewatering (EAD), which capitalizes on the adaptation of synergistic effects of electric and acoustic fields to commercial coal dewatering systems, such as belt filter presses. Objectives are: (1) to validate the expected technical feasibility and energy conservation\\/economic benefits of the EAD process as applied to fine (-100 mesh) and ultrafine (-325 mesh)

H. S. Muralidhara; B. F. Jirjis; N. Senapati; R. Menton; P. Hsieh; S. H. Chiang; Y. S. Cheng; S. P. Chauhan; Battelle Memorial Inst; OH Columbus

1989-01-01

332

Environmentally persistent free radicals amplify ultrafine particle mediated cellular oxidative stress and cytotoxicity  

Microsoft Academic Search

BACKGROUND: Combustion generated particulate matter is deposited in the respiratory tract and pose a hazard to the lungs through their potential to cause oxidative stress and inflammation. We have previously shown that combustion of fuels and chlorinated hydrocarbons produce semiquinone-type radicals that are stabilized on particle surfaces (i.e. environmentally persistent free radicals; EPFRs). Because the composition and properties of actual

Shrilatha Balakrishna; Slawo Lomnicki; Kevin M McAvey; Richard B Cole; Barry Dellinger; Stephania A Cormier

2009-01-01

333

Fine and ultrafine particles generated during fluidized bed combustion of different solid fuels  

SciTech Connect

The paper reports an experimental study carried out with a 110-mm ID fluidized bed combustor focused on the characterization of particulates formation/emission during combustion of coal and non-fossil solid fuels. Fuels included: a bituminous coal, a commercial predried and granulated sludge (GS), a refuse-derived fuel (RDF), and a biomass waste (pine seed shells). Stationary combustion experiments were carried out analyzing the fate of fuel ashes. Fly ashes collected at the combustor exhaust were characterized both in terms of particle size distribution and chemical composition, with respect to both trace and major elements. Tapping-Mode Atomic Force Microscopy (TM-AFM) technique and high-efficiency cyclone-type collector devices were used to characterize the size and morphology of the nanometric-and micronic-size fractions of fly ash emitted at the exhaust respectively. Results showed that during the combustion process: I) the size of the nanometric fraction ranges between 2 and 65 nm; ii) depending on the fuel tested, combustion-assisted attrition or the production of the primary ash particles originally present in the fuel particles, are responsible of fine particle generation. The amount in the fly ash of inorganic compounds is larger for the waste-derived fuels, reflecting the large inherent content of these compounds in the parent fuels.

Urciuolo, M.; Barone, A.; D'Alessio, A.; Chirone, R. [CNR, Rome (Italy). Institute of Research for Combustion

2008-12-15

334

Ultrafine particles and nitrogen oxides generated by gas and electric cooking  

Microsoft Academic Search

OBJECTIVESTo measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens.METHODSExperiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NOx) were measured by a chemiluminescent ML9841A NOx analyser.

M Dennekamp; S Howarth; C A J Dick; J W Cherrie; K Donaldson; A Seaton

2001-01-01

335

The characteristics of ultrafine particles produced freeze-drying and by precipitation  

SciTech Connect

We have investigated the characteristics of powders produced by two techniques: (1) freeze-drying, and (2) precipitation from a liquid medium. Powders of ionic compounds: RbCl and TlF have been produced by freeze-drying. By optimizing this technique, it is possible to produce powders comprising small, 10 ..mu..m agglomerates of primary particles with average sizes between 0.1--0.5 ..mu..m. These agglomerates can be broken into primary particles by sonication. We have also precipitated RbCl and TlF powders from an aqueous solution by adding isopropanol. These powders consist of large agglomerates of primary particles, 0.5 ..mu..m to 10 ..mu..m in size, which do not respond well to sonication, but may be subdivided by mechanical milling. We have also adapted a chemical precipitation technique for producing 0.2 ..mu..m diameter primary particles of Y/sub 2/O/sub 3/. 4 refs., 5 figs.

Panitz, J.K.G.

1988-01-01

336

Estimation of ultrafine particle concentrations at near-highway residences using data from local and central monitors  

NASA Astrophysics Data System (ADS)

Ultrafine particles (UFP; aerodynamic diameter < 0.1 ?m) are a ubiquitous exposure in the urban environment and are elevated near highways. Most epidemiological studies of UFP health effects use central site monitoring data, which may misclassify exposure. Our aims were to: (1) examine the relationship between distant and proximate monitoring sites and their ability to predict hourly UFP concentration measured at residences in an urban community with a major interstate highway and; (2) determine if meteorology and proximity to traffic improve explanatory power. Short-term (1-3 weeks) residential monitoring of UFP concentration was conducted at 18 homes. Long-term monitoring was conducted at two near-highway monitoring sites and a central site. We created models of outdoor residential UFP concentration based on concentrations at the near-highway site, at the central site, at both sites together and without fixed sites. UFP concentration at residential sites was more highly correlated with those at a near-highway site than a central site. In regression models of each site alone, a 10% increase in UFP concentration at a near-highway site was associated with a 6% (95% CI: 6%, 7%) increase at residences while a 10% increase in UFP concentration at the central site was associated with a 3% (95% CI: 2%, 3%) increase at residences. A model including both sites showed minimal change in the magnitude of the association between the near-highway site and the residences, but the estimated association with UFP concentration at the central site was substantially attenuated. These associations remained after adjustment for other significant predictors of residential UFP concentration, including distance from highway, wind speed, wind direction, highway traffic volume and precipitation. The use of a central site as an estimate of personal exposure for populations near local emissions of traffic-related air pollutants may result in exposure misclassification.

Fuller, Christina H.; Brugge, Doug; Williams, Paige L.; Mittleman, Murray A.; Durant, John L.; Spengler, John D.

2012-09-01

337

Estimation of ultrafine particle concentrations at near-highway residences using data from local and central monitors.  

PubMed

Ultrafine particles (UFP; aerodynamic diameter < 0.1 micrometers) are a ubiquitous exposure in the urban environment and are elevated near highways. Most epidemiological studies of UFP health effects use central site monitoring data, which may misclassify exposure. Our aims were to: (1) examine the relationship between distant and proximate monitoring sites and their ability to predict hourly UFP concentration measured at residences in an urban community with a major interstate highway and; (2) determine if meteorology and proximity to traffic improve explanatory power. Short-term (1 - 3 weeks) residential monitoring of UFP concentration was conducted at 18 homes. Long-term monitoring was conducted at two near-highway monitoring sites and a central site. We created models of outdoor residential UFP concentration based on concentrations at the near-highway site, at the central site, at both sites together and without fixed sites. UFP concentration at residential sites was more highly correlated with those at a near-highway site than a central site. In regression models of each site alone, a 10% increase in UFP concentration at a near-highway site was associated with a 6% (95% CI: 6%, 7%) increase at residences while a 10% increase in UFP concentration at the central site was associated with a 3% (95% CI: 2%, 3%) increase at residences. A model including both sites showed minimal change in the magnitude of the association between the near-highway site and the residences, but the estimated association with UFP concentration at the central site was substantially attenuated. These associations remained after adjustment for other significant predictors of residential UFP concentration, including distance from highway, wind speed, wind direction, highway traffic volume and precipitation. The use of a central site as an estimate of personal exposure for populations near local emissions of traffic-related air pollutants may result in exposure misclassification. PMID:23645993

Fuller, Christina H; Brugge, Doug; Williams, Paige; Mittleman, Murray; Durant, John L; Spengler, John D

2012-09-01

338

Using mobile monitoring to characterize roadway and aircraft contributions to ultrafine particle concentrations near a mid-sized airport  

NASA Astrophysics Data System (ADS)

Ultrafine particles (UFP) have complex spatial and temporal patterns that can be difficult to characterize, especially in areas with multiple source types. In this study, we utilized mobile monitoring and statistical modeling techniques to determine the contributions of both roadways and aircraft to spatial and temporal patterns of UFP in the communities surrounding an airport. A mobile monitoring campaign was conducted in five residential areas surrounding T.F. Green International Airport (Warwick, RI, USA) for one week in both spring and summer of 2008. Monitoring equipment and geographical positioning system (GPS) instruments were carried following scripted walking routes created to provide broad spatial coverage while recognizing the complexities of simultaneous spatial and temporal heterogeneity. Autoregressive integrated moving average models (ARIMA) were used to predict UFP concentrations as a function of distance from roadway, landing and take-off (LTO) activity, and meteorology. We found that distance to the nearest Class 2 roadway (highways and connector roads) was inversely associated with UFP concentrations in all neighborhoods. Departures and arrivals on a major runway had a significant influence on UFP concentrations in a neighborhood proximate to the end of the runway, with a limited influence elsewhere. Spatial patterns of regression model residuals indicate that spatial heterogeneity was partially explained by traffic and LTO terms, but with evidence that other factors may be contributing to elevated UFP close to the airport grounds. Regression model estimates indicate that mean traffic contributions exceed mean LTO contributions, but LTO activity can dominate the contribution during some minutes. Our combination of monitoring and statistical modeling techniques demonstrated contributions from major surrounding runways and LTO activity to UFP concentrations near a mid-sized airport, providing a methodology for source attribution within a community with multiple distinct sources.

Hsu, Hsiao-Hsien; Adamkiewicz, Gary; Houseman, E. Andres; Spengler, John D.; Levy, Jonathan I.

2014-06-01

339

Novel method of doping tungsten into zinc oxide ultrafine particle using RF plasma system  

Microsoft Academic Search

A tungsten plate was set on a one-plate electrode in RF plasma, using parallel plates in a mixed gas of argon (9.75Torr) and oxygen (0.25Torr). Zn smoke was introduced into the plasma field. W atoms were doped in the ZnO smoke formation field in the RF plasma system. The resulting particles with a size of 30nm were identified to be

T. Sato; H. Suzuki; O. Kido; M. Kurumada; K. Kamitsuji; Y. Kimura; A. Takeda; S. Kaneko; Y. Saito; C. Kaito

2004-01-01

340

Redox Dynamics of Mixed Metal (Mn, Cr, and Fe) Ultrafine Particles  

SciTech Connect

The impact of particle composition on metal oxidation state, and on changes in oxidation state with simulated atmospheric aging, are investigated experimentally in flame-generated nanoparticles containing Mn, Cr, and Fe. The results demonstrate that the initial fraction of Cr(VI) within the particles decreases with increasing total metal concentration in the flame. In contrast, the initial Mn oxidation state was only partly controlled by metal loading, suggesting the importance of other factors. Two reaction pathways, one reductive and one oxidative, were found to be operating simultaneously during simulated atmospheric aging. The oxidative pathway depended upon the presence of simulated sunlight and O{sub 3}, whereas the reductive pathway occurred in the presence of simulated sunlight alone. The reductive pathway appears to be rapid but transient, allowing the oxidative pathway to dominate with longer aging times, i.e. greater than {approx}8 hours. The presence of Mn within the particles enhanced the importance of the oxidative pathway, leading to more net Cr oxidation during aging implying that Mn can mediate oxidation by removal of electrons from other particulate metals.

Nico, Peter S.; Kumfer, Benjamin M.; Kennedy, Ian M.; Anastasio, Cort

2008-08-01

341

Redox Dynamics of Mixed Metal (Mn, Cr, and Fe) Ultrafine Particles  

PubMed Central

The impact of particle composition on metal oxidation state, and on changes in oxidation state with simulated atmospheric aging, are investigated experimentally in flame-generated nanoparticles containing Mn, Cr, and Fe. The results demonstrate that the initial fraction of Cr(VI) within the particles decreases with increasing total metal concentration in the flame. In contrast, the initial Mn oxidation state was only partly controlled by metal loading, suggesting the importance of other factors. Two reaction pathways, one reductive and one oxidative, were found to be operating simultaneously during simulated atmospheric aging. The oxidative pathway depended upon the presence of simulated sunlight and O3, whereas the reductive pathway occurred in the presence of simulated sunlight alone. The reductive pathway appears to be rapid but transient, allowing the oxidative pathway to dominate with longer aging times, i.e. greater than ?8 hours. The presence of Mn within the particles enhanced the importance of the oxidative pathway, leading to more net Cr oxidation during aging implying that Mn can mediate oxidation by removal of electrons from other particulate metals.

Nico, Peter S.; Kumfer, Benjamin M.; Kennedy, Ian M.; Anastasio, Cort

2008-01-01

342

Seasonal and spatial variability in chemical composition and mass closure of ambient ultrafine particles in the megacity of Los Angeles.  

PubMed

Emerging toxicological research has shown that ultrafine particles (UFP, dp < 0.1–0.2 ?m) may be more potent than coarse or fine particulate matter. To better characterize quasi-UFP (PM0.25, dp < 0.25 ?m), we conducted a year-long sampling campaign at 10 distinct areas in the megacity of Los Angeles, including source, near-freeway, semi-rural receptor and desert-like locations. Average PM0.25 mass concentration ranged from 5.9 to 16.1 ?g m?3 across the basin and over different seasons. Wintertime levels were highest at the source site, while lowest at the desert-like site. Conversely, summertime concentrations peaked at the inland receptor locations. Chemical mass reconstruction revealed that quasi-UFP in the basin consisted of 49–64% organic matter, 3–6.4% elemental carbon, 9–15% secondary ions (SI), 0.7–1.3% trace ions, and 5.7–17% crustal material and trace elements, on a yearly average basis. Organic carbon (OC), a major constituent of PM0.25, exhibited greatest concentrations in fall and winter at all sites, with the exception of the inland areas. Atmospheric stability conditions and particle formation favored by condensation of low-volatility organics contributed to these levels. Inland, OC concentrations peaked in summer due to increased PM0.25 advection from upwind sources coupled with secondary organic aerosol formation. Among SI, nitrate peaked at semi-rural Riverside sites, located downwind of strong ammonia sources. Moreover, ionic balance indicated an overall neutral quasi-UFP aerosol, with somewhat lower degree of neutralization at near-freeway sites in winter. Anthropogenic metals peaked at the urban sites in winter while generally increased at the receptor areas in summer. Lastly, coefficients of divergence analysis showed that while PM0.25 mass is relatively spatially homogeneous in the basin, some of its components, mainly EC, nitrate and several toxic metals, are unevenly distributed. These results suggest that population exposure to quasi-UFP can substantially vary by season and over short spatial scales in the megacity of Los Angeles. PMID:24592446

Daher, Nancy; Hasheminassaba, Sina; Shafer, Martin M; Schauer, James J; Sioutas, Constantinos

2013-01-01

343

FORMATION OF FINE PARTICLES FROM RESIDUAL OIL COMBUSTION: REDUCING ULTRAFINE NUCLEI THROUGH THE ADDITION OF INORGANIC SORBENT  

EPA Science Inventory

The paper gives results of an investigation, using an 82-kW-rated laboratory-scale refractory-lined combustor, of the characteristics of particulate matter emitted from residual oil combustion and the reduction of ultrafine nuclei by postflame sorbent injection. Without sorbent a...

344

On-road measurements of ultrafine particle concentration profiles and their size distributions inside the longest highway tunnel in Southeast Asia  

NASA Astrophysics Data System (ADS)

This study measured ultrafine particle (UFP) levels and their size distributions in the Hsuehshan tunnel from August 12 to 19, 2009, using a Fast Mobility Particle Sizer. Measurement results demonstrate that traffic volume, the slope of the tunnel (downhill or uphill) and the ventilation system affected UFP levels inside the tunnel. Average UFP levels were about 1.0 × 10 5-3.0 × 10 5 particles cm -3 at normal traffic volume. A traffic jam in the tunnel could raise UFP levels to over 1.0 × 10 6 particles cm -3. UFP levels at the uphill bore were significantly higher than those at the downhill bore due to high UFP levels exhausted from vehicles going uphill at high engine load conditions. UFP levels eventually diluted 10-50% with fresh air from tunnel air shafts. Gas-to-particle condensation conversion markedly produced nucleation mode particles at the tunnel entrance section. Observations also showed Aitken mode particles markedly formed by coagulation growth of nucleation mode particles in the tunnel middle section and exit section. That is, the particle size distributions changed significantly inside the tunnel. Measurement results suggest that particles in the Aitken mode in the long tunnel governed UFP levels.

Cheng, Yu-Hsiang; Liu, Zhen-Shu; Chen, Chih-Chieh

2010-02-01

345

Development of Ultrafine, Lamellar Structures in Two-Phase {gamma}-TiAl Alloys  

SciTech Connect

Processing of two-phase gamma-TiAl alloys (Ti-47Al-2Cr-2Nb or minor modifications thereof) above the alpha-transus temperature (T {sub alpha}) produced unique refined-colony/ultrafine lamellar structures in both powder- and ingot-metallurgy (P/M and I/M, respectively) alloys. These ultrafine lamellar structures consist of fine laths of the gamma and alpha {sub 2} phases, with average interlamellar spacings (lambda {sub Lambda}) of 100-200 nm and alpha {sub 2}-alpha {sub 2} spacings (lambda {sub alpha}) of 200-500 nm, and are dominated by gamma/alpha {sub 2} interfaces. This characteristic microstructure forms by extruding P/M Ti-47Al-2Cr-2Nb alloys above T {sub alpha}, and also forms with finer colony size but slightly coarser fully-lamellar structures by hot-extruding similar I/M alloys. Alloying additions of B and W refine lambda {sub L} and lambda {sub alpha} in both I/M Ti-47Al (cast and heat-treated above T {sub alpha}) or in extruded Ti-47Al-2Cr-2Nb alloys. The ultrafine lamellar structure in the P/M alloy remains stable during heat-treatment at 900 {degrees}C for 2h, but becomes unstable after 4h at 982 {degrees}C; the ultrafine lamellar structure remains relatively stable after aging for {gt}5000 h at 800 {degrees}C. Additions of B+W dramatically improve the coarsening resistance of lambda L and lambda alpha in the I/M Ti-47Al alloys aged for 168 h at 1000{degrees}C. In both the P/M and I/M Ti-47Al-2Cr-2Nb alloys, these refined-colony/ultrafine-lamellar structures correlate with high strength and good ductility at room temperature, and very good strength at high temperatures. While refining the colony size improves the room-temperature ductility, alloys with finer lambda {sub L} are stronger at both room- and high-temperatures. Additions of B+W produce finer as-processed lambda {sub L} and lambda {sub alpha} in I/M TiAl alloys, and stabilize such structures during heat-treatment or aging.

Maziasz, P.J., Liu, C.T.

1997-12-31

346

Simulation of in situ ultrafine particle formation in the eastern United States using PMCAMx-UF  

Microsoft Academic Search

A three-dimensional chemical transport model has been developed incorporating the Dynamic Model for Aerosol Nucleation for the simulation of aerosol dynamics into the regional model PMCAMx. Using a scaled version of the ternary H2SO4-NH3-H2O nucleation theory and the Two Moment Aerosol Sectional algorithm, the new model (PMCAMx-UF) is used to simulate a summertime period in the eastern United States. The

JaeGun Jung; Christos Fountoukis; Peter J. Adams; Spyros N. Pandis

2010-01-01

347

Relaxation in ordered systems of ultrafine magnetic particles: effect of the exchange interaction  

NASA Astrophysics Data System (ADS)

We perform Monte Carlo simulations to study the relaxation of single-domain nanoparticles that are located on a simple cubic lattice with anisotropy axes pointing in the z-direction, under the combined influence of anisotropy energy, dipolar interaction and ferromagnetic interaction of strength J. We compare the results of classical Heisenberg systems with three-dimensional magnetic moments \\vec \\mu_i to those of Ising systems and find that Heisenberg systems show a much richer and more complex dynamical behavior. In contrast to Heisenberg systems, Ising systems need large activation energies to turn a spin and also possess a smaller configuration space for the orientation of the \\vec \\mu_i . Accordingly, Heisenberg systems possess a whole landscape of different states with very close-lying energies, while Ising systems tend to get frozen in one random state far away from the ground state. For Heisenberg systems, we identify two phase transitions: (i) at intermediate J between domain and layered states and (ii) at larger J between layered and ferromagnetic states. Between these two transitions, the layered states change their appearance and develop a sub-structure, where the orientation of the \\vec \\mu_i in each layer depends on J, so that for each value of J, a new ground state appears.

Russ, Stefanie; Bunde, Armin

2011-03-01

348

Relaxation in ordered systems of ultrafine magnetic particles: effect of the exchange interaction.  

PubMed

We perform Monte Carlo simulations to study the relaxation of single-domain nanoparticles that are located on a simple cubic lattice with anisotropy axes pointing in the z-direction, under the combined influence of anisotropy energy, dipolar interaction and ferromagnetic interaction of strength J. We compare the results of classical Heisenberg systems with three-dimensional magnetic moments [Formula: see text] to those of Ising systems and find that Heisenberg systems show a much richer and more complex dynamical behavior. In contrast to Heisenberg systems, Ising systems need large activation energies to turn a spin and also possess a smaller configuration space for the orientation of the [Formula: see text]. Accordingly, Heisenberg systems possess a whole landscape of different states with very close-lying energies, while Ising systems tend to get frozen in one random state far away from the ground state. For Heisenberg systems, we identify two phase transitions: (i) at intermediate J between domain and layered states and (ii) at larger J between layered and ferromagnetic states. Between these two transitions, the layered states change their appearance and develop a sub-structure, where the orientation of the [Formula: see text] in each layer depends on J, so that for each value of J, a new ground state appears. PMID:21378444

Russ, Stefanie; Bunde, Armin

2011-03-30

349

Development of ultra-fine grained W TiC and their mechanical properties for fusion applications  

NASA Astrophysics Data System (ADS)

Effects of neutron irradiation on microstructural evolution and radiation hardening were examined for fine-grained W-0.3 wt%TiC (grain size of 0.9 ?m) and commercially available pure W (20 ?m). Both materials were neutron irradiated at 563 K to 9 × 10 23 n/m 2 ( E > 1 MeV) in the Japan Materials Testing Reactor (JMTR). Post-irradiation examinations showed that the microstructural changes and the degree of hardening due to irradiation were significantly reduced for fine-grained W-0.3TiC compared with pure W, demonstrating the significance of grain refinement to improve radiation resistance. In order to develop ultra-fine grained W-TiC compacts with nearly full densification, the fabrication process was modified, so that W-(0.3-0.7)%TiC with 0.06-0.2 ?m grain size and 99% of relative density was fabricated. The achievable grain refinement depended on TiC content and milling atmosphere. The three-point bending fracture strength at room temperature for ultra-fine grained W-TiC compacts of powder milled in H 2 reached approximately 1.6-2 GPa for composition near 0.5%TiC.

Kurishita, H.; Amano, Y.; Kobayashi, S.; Nakai, K.; Arakawa, H.; Hiraoka, Y.; Takida, T.; Takebe, K.; Matsui, H.

2007-08-01

350

Hygroscopic properties of newly formed ultrafine particles at an urban site surrounded by a deciduous forest in northern Japan during the summer of 2011  

NASA Astrophysics Data System (ADS)

To investigate the hygroscopic property of ultrafine particles during the new particle formation event, hygroscopic growth factors (g(RH)) of size-segregated atmospheric particles were measured at an urban site in Sapporo, northern Japan, during the summer of 2011. Hygroscopic growth factors at 85% RH (g(85%)) of freshly formed nucleation mode particles were measured at a dry particle diameter (Dp) centered at 20 nm to be 1.11 to 1.28 (average 1.16 ± 0.06), which are equivalent to 1.17 to 1.35 (1.23 ± 0.06) for a dry Dp centered at 100 nm after considering the Kelvin effect. These values are comparable with those of secondary organic aerosols, suggesting that low-volatility organic vapors are important to the burst of nucleation mode particles at the measurement site surrounded by a deciduous forest. Gradual increases in mode diameter after the burst of nucleation mode particles were obtained under southerly wind condition with a dominant contribution of intermediately-hygroscopic particles. However, sharp increases in mode diameter were obtained when wind direction shifted to northwesterly or northeasterly with a sharp increase in highly-hygroscopic particle faction in the Aitken mode particles, indicating that local wind direction is an important factor controlling the growth of newly formed particles and their hygroscopic properties. Higher g(85%) values (1.27 ± 0.05) were obtained at a dry Dp of 120 nm when the air masses originated from the Asian Continent, whereas lower g(85%) values (1.19 ± 0.06) were obtained when clean marine air masses arrived at the urban site. These results indicate that the hygroscopic property of large Aitken and small accumulation mode particles (80-165 nm) is highly influenced by the long-range atmospheric transport of particles and their precursors.

Jung, J.; Kawamura, K.

2014-03-01

351

Ultrafine atmospheric aerosols, clouds and climate  

NASA Astrophysics Data System (ADS)

Changes in atmospheric aerosol due to anthropogenic emissions are the most uncertain factors that have contributed to recent climate change. Much of this uncertainty is from the effect that particles have on cloud radiative properties, the aerosol indirect effect. Particles on which cloud droplets form are called cloud condensation nuclei (CCN). Particles larger than about 80--100 nm dry diameter typically act as CCN in stratus clouds. In order to predict how cloud radiative properties have changed since pre-industrial times, the CCN concentrations in both present-day and pre-industrial times must be known. Much of the uncertainty in CCN predictions is from uncertainty in the sources of ultrafine particles (particles with diameter smaller than 100 nm) as well as the processes that grow these particles to CCN sizes. This thesis explores various aspects of the how uncertainties in ultrafine particles affect predictions of CCN. First, we explore the uncertainty in CCN due to uncertain sea-salt emissions and also the affect of recently quantified ultrafine sea-salt on CCN. In the Southern Ocean, uncertainty in sea-salt emissions contributed to uncertainties in CCN(0.2%) by a factor of 2. Ultrafine sea-salt aerosol increased CCN(0.2%) in remote marine regions by more than 20%. Next, we look at how primary carbonaceous particles affect CCN as well as how uncertainties in their chemical properties affect CCN. The addition of primary carbonaceous aerosol increased CCN(0.2%) concentrations by 65--90% in the globally averaged surface layer. A sensitivity study showed that approximately half of this increase occurs even if all carbonaceous aerosols are completely insoluble. To study the growth of ultrafine particles to CCN sizes, we develop the Probability of Ultrafine Growth (PUG) model. It was found in most cases that condensation is the dominant growth mechanism and coagulation with larger particles is the dominant sink mechanism for ultrafine particles. We found that the probability of a 30 nm ultrafine particle generating a 100 nm CCN varies from <0.1% to ˜90% in different parts of the atmosphere. For a given mass of primary ultrafine aerosol, an uncertainty of a factor of two in the median emission diameter can lead to an uncertainty in the number of CCN generated as high as a factor for eight. Next, we develop a method for parameterizing sub-grid scale aerosol dynamics of freshly-emitted aerosol. This approach is based on the calculation of the probability that a given particle emitted inside a computational grid cell will survive and be available for transfer outside the cell. The method for applying the sub-grid coagulation parameterization to a CTM is discussed. In order to elucidate the computational burden of simulating aerosol nucleation in 3-D models, we derive the pseudo-steady-state approximation (PSSA) for sulfuric acid vapor and tested it in a box model with size-resolved aerosol microphysics. The associated errors in prediction of the sulfuric acid vapor concentration and particle concentrations are small. The PSSA model was faster than a model that explicitly solves for the sulfuric acid vapor concentration in 97% of the tests, more than ten times faster in 91% of the points, and more than 100 times faster in 69% of the tests. Next, we evaluate the sensitivity of CCN(0.2%) concentrations to changes in the nucleation rates. The difference in predicted nucleation rates in simulations using a binary nucleation parameterization and a ternary nucleation parameterization was six orders of magnitude, globally. The global CCN(0.2%) concentration was 12% higher when the ternary parameterization was used instead of the binary parameterization. The sensitivity of CCN(0.2%) to changes in nucleation rate increased both when the primary particle emissions were reduced and when the SOA formation rates were increased. In our pre-industrial simulations, the sensitivity of CCN(0.2%) to the nucleation rates were similar to the present day simulations. We found that the proposed ion-aerosol clear-air mechanism cannot explain t

Pierce, Jeffrey Robert

352

Production of Ultrafine, High-Purity Ceramic Powders Using the US Bureau of Mines Developed Turbomill.  

National Technical Information Service (NTIS)

Turbomilling, an innovative grinding technology developed by the U.S. Bureau of Mines in the early 1960's for delaminating filler-grade kaolinitic clays, has been expanded into the areas of particle size reduction, material mixing, and process reaction ki...

J. L. Hoyer

1993-01-01

353

Ultrafine particle levels at an international port of entry between the US and Mexico: exposure implications for users, workers, and neighbors.  

PubMed

Exposure to diesel-emitted particles has been linked to increased cancer risk and cardiopulmonary diseases. Because of their size (<100 nm), exposure to ultrafine particles (UFPs) emitted from heavy-duty diesel vehicles (HDDV) might result in greater health risks than those associated with larger particles. Seasonal UFP levels at the International Bridge of the Americas, which connects the US and Mexico and has high HDDV traffic demands, were characterized. Hourly average UFP concentrations ranged between 1.7 × 10(3)/cc and 2.9 × 10(5)/cc with a mean of 3.5 × 10(4)/cc. Wind speeds <2 m?s(-1) and temperatures <15?°C were associated with particle number concentrations above normal conditions. The presence of HDDV had the strongest impact on local UFP levels. Varying particle size distributions were associated with south- and northbound HDDV traffic. Peak exposure occurred on weekday afternoons. Although in winter, high exposure episodes were also observed in the morning. Particle number concentrations were estimated to reach background levels at 400 m away from traffic. The populations exposed to UFP above background levels include law enforcement officers, street vendors, private commuters, and commercial vehicle drivers as well as neighbors on both sides of the border, including a church and several schools. PMID:23321858

Olvera, Hector A; Lopez, Mario; Guerrero, Veronica; Garcia, Humberto; Li, Wen-Whai

2013-01-01

354

Development of the Electroacoustic Dewatering (EAD) process for fine/ultrafine coal  

SciTech Connect

This report describes an advanced process, called Electroacoustic Dewatering (EAD), which capitalizes on the adaptation of synergistic effects of electric and acoustic fields to commercial coal dewatering systems, such as belt filter presses. Objectives are: (1) to validate the expected technical feasibility and energy conservation/economic benefits of the EAD process as applied to fine ({minus}100 mesh) and ultrafine ({minus}325 mesh) coal; and (2) to obtain data from a continuous, process research unit (PRU) in order to conduct a reliable economic analysis and to design commercial EAD filters as well as to promote adaptation of the process by the coal preparation industry. During this quarter, our efforts were focused on material selection, acquisition, and characterization and on laboratory EAD tests. 8 figs., 6 tabs.

Muralidhara, H.S.; Jirjis, B.F.; Senapati, N.; Menton, R.; Hsieh, P.; Chiang, S.H.; Cheng, Y.S.; Chauhan, S.P. (Battelle Memorial Inst., Columbus, OH (USA); Pittsburgh Univ., PA (USA). Dept. of Chemical Engineering; Battelle Memorial Inst., Columbus, OH (USA))

1989-10-30

355

Development of the Electroacoustic Dewatering (EAD) process for fine/ultrafine coal  

SciTech Connect

Electroacoustic Dewatering (EAD) capitalizes on the adaptation of synergistic effects of electric and acoustic fields to commercial coal dewatering systems, such as belt filter presses. The Battelle project for demonstrating the potential for commercial application of the EAD process for coal has the following objectives: to validate the expected technical feasibility and energy conservation/economic benefits of the EAD process as applied to fine (-100 mesh) and ultrafine (-325 mesh) coal; and to obtain data from a continuous, process research unit (PRU) in order to conduct a reliable economic analysis and to design commercial EAD filters as well as to promote adaptation of the process by the coal preparation industry. During this quarter, efforts were directed towards completion of PRU operation. The paper describes results from field testing on miners 325 mesh Upper Freeport coal and discusses the effects of experimental factors on final cake solids and on delta solids and linear regression models. 4 figs., 4 tabs.

Kim, B.C.; Criner, C.L.; Senapati, N.; Menton, R.; Chou, Y.L.; Chauhan, S.P.

1991-01-25

356

Ultrafine cementitious grout  

DOEpatents

An ultrafine cementitious grout is described having a particle size 90% of which are less than 6 {micro}m in diameter and an average size of about 2.5 {micro}m or less, and preferably 90% of which are less than 5 {micro}m in diameter and an average size of about 2 {micro}m or less containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 40 wt. % to about 50 wt. % Portland cement; from about 50 wt. % to about 60 wt. % pumice containing at least 60% amorphous silicon dioxide; and from 0.1 wt. % to about 1.5 wt. % superplasticizer. The grout is mixed with water in the W/CM ratio of about 0.4--0.6/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 {micro}m in width. 4 figs.

Ahrens, E.H.

1998-07-07

357

Influences of traffic volumes and wind speeds on ambient ultrafine particle levels—Observations at a highway electronic toll collection (ETC) lane  

NASA Astrophysics Data System (ADS)

The levels of ultrafine particles (UFPs) and their size distributions on a highway electronic toll collection (ETC) lane were measured from October 30 to November 1 and November 5 to November 6, 2008. The hourly UFP levels measured at the highway ETC lane were 1.3 × 10 4-1.9 × 10 5 particles cm -3 (mean = 9.4 × 10 4 particles cm -3). Compared with urban UFP levels, average UFP levels at the highway ETC lane were about 5-10 times higher than those previously measured in urban areas, indicating that a considerable amount of UFPs were exhausted from vehicles. At the highway ETC lane, the average UFP number size distribution had a dominant mode at about 10 nm and a minor mode at about 33 nm. Measurement results indicate that nucleation mode particles remained at relatively high levels compared to Aitken mode and accumulation mode particles at the highway ETC lane. This study identifies the impacts of traffic volumes and wind speeds on ambient UFP levels. Measurement results show that the elevated UFP levels resulting from traffic volume decreased exponentially as wind speed increased on the highway when wind speed was <2.0 m s -1. However, the elevated UFP levels resulting from traffic volume increased slightly when wind speed was >2.0 m s -1 due to local turbulent mixing causes UFPs at high wind speeds. According to measurement results, high levels of UFP were observed at low wind speeds and under high traffic volumes.

Cheng, Yu-Hsiang; Li, Yi-Sheng

2011-01-01

358

Frequency-dependent AMS of rocks as a tool for the investigation of the fabric of ultrafine magnetic particles  

NASA Astrophysics Data System (ADS)

In some geological processes, new very fine-grained magnetic minerals may originate. The variation in content of these minerals is routinely investigated by frequency-dependent magnetic susceptibility, which is traditionally interpreted in terms of presence of viscous superparamagnetic (SP) particles in addition to stable single domain (SSD) and multidomain (MD) magnetic particles. In addition, the fabric of these grains can be investigated through the frequency-dependent AMS. Through standard AMS measurement at different frequencies, one can evaluate the contribution of SP particles to the whole-rock AMS; appropriate methods were developed. Various rocks, soils and ceramics, showing frequency-dependent magnetic susceptibility, were investigated. Measurable changes of AMS with operating frequency were revealed and attempts are made of their fabric interpretation.

Hrouda, Frantisek; Jezek, Josef

2014-05-01

359

Short-term exposure to PM 10, PM 2.5, ultrafine particles and CO 2 for passengers at an intercity bus terminal  

NASA Astrophysics Data System (ADS)

The Taipei Bus Station is the main transportation hub for over 50 bus routes to eastern, central, and southern Taiwan. Daily traffic volume at this station is about 2500 vehicles, serving over 45,000 passengers daily. The station is a massive 24-story building housing a bus terminal, a business hotel, a shopping mall, several cinemas, offices, private residential suites, and over 900 parking spaces. However, air quality inside this bus terminal is a concern as over 2500 buses are scheduled to run daily. This study investigates the PM 10, PM 2.5, UFP and CO 2 levels inside and outside the bus terminal. All measurements were taken between February and April 2010. Measurement results show that coarse PM inside the bus terminal was resuspended by the movement of large numbers of passengers. The fine and ultrafine PM in the station concourse were from outside vehicles. Moreover, fine and ultrafine PM at waiting areas were exhausted directly from buses in the building. The CO 2 levels at waiting areas were likely elevated by bus exhaust and passengers exhaling. The PM 10, PM 2.5 and CO 2 levels at the bus terminal were lower than Taiwan's EPA suggested standards for indoor air quality. However, UFP levels at the bus terminal were significantly higher than those in the urban background by about 10 times. Therefore, the effects of UFPs on the health of passengers and workers must be addressed at this bus terminal since the levels of UFPs are higher than >1.0 × 10 5 particles cm -3.

Cheng, Yu-Hsiang; Chang, Hsiao-Peng; Hsieh, Cheng-Ju

2011-04-01

360

Changes in pulmonary lavage fluid of guinea pigs exposed to ultrafine zinc oxide with adsorbed sulfuric acid  

Microsoft Academic Search

Ultrafine metal oxide particles (diameters less than 0.1 ?m) and sulfur dioxide are important products of coal combustion. Interaction of these products in the effluent stream results in formation of ultrafine particles with adsorbed sulfur compounds, including sulfuric acid. The toxicity of ultrafine zinc oxide particles with adsorbed sulfuric acid was evaluated by comparing pulmonary lavage fluid from guinea pigs

Michael W. Conner; William H. Flood; Adrianne E. Rogers; Mary O. Amdur

1989-01-01

361

Development of the Electroacoustic Dewatering (EAD) process for fine/ultrafine coal: First quarterly progress report, period ending December 15, 1988  

SciTech Connect

Battelle, in cooperation with the Electric Power Research Institute (EPRI), Ashbrook-Simon-Hartley (ASH), Kaiser Engineers (KE), Lewis Corporation, and Prof. S.H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to a commercial belt filter press design that is used in many other applications. 1 fig.

Not Available

1989-01-05

362

Comparison of carcinogen, carbon monoxide, and ultrafine particle emissions from narghile waterpipe and cigarette smoking: Sidestream smoke measurements and assessment of second-hand smoke emission factors  

PubMed Central

The lack of scientific evidence on the constituents, properties, and health effects of second-hand waterpipe smoke has fueled controversy over whether public smoking bans should include the waterpipe. The purpose of this study was to investigate and compare emissions of ultrafine particles (UFP, <100 nm), carcinogenic polyaromatic hydrocarbons (PAH), volatile aldehydes, and carbon monoxide (CO) for cigarettes and narghile (shisha, hookah) waterpipes. These smoke constituents are associated with a variety of cancers, and heart and pulmonary diseases, and span the volatility range found in tobacco smoke. Sidestream cigarette and waterpipe smoke was captured and aged in a 1 m3 Teflon-coated chamber operating at 1.5 air changes per hour (ACH). The chamber was characterized for particle mass and number surface deposition rates. UFP and CO concentrations were measured online using a fast particle spectrometer (TSI 3090 Engine Exhaust Particle Sizer), and an indoor air quality monitor. Particulate PAH and gaseous volatile aldehydes were captured on glass fiber filters and DNPH-coated SPE cartridges, respectively, and analyzed off-line using GC–MS and HPLC–MS. PAH compounds quantified were the 5- and 6-ring compounds of the EPA priority list. Measured aldehydes consisted of formaldehyde, acetaldehyde, acrolein, methacrolein, and propionaldehyde. We found that a single waterpipe use session emits in the sidestream smoke approximately four times the carcinogenic PAH, four times the volatile aldehydes, and 30 times the CO of a single cigarette. Accounting for exhaled mainstream smoke, and given a habitual smoker smoking rate of 2 cigarettes per hour, during a typical one-hour waterpipe use session a waterpipe smoker likely generates ambient carcinogens and toxicants equivalent to 2–10 cigarette smokers, depending on the compound in question. There is therefore good reason to include waterpipe tobacco smoking in public smoking bans.

Daher, Nancy; Saleh, Rawad; Jaroudi, Ezzat; Sheheitli, Hiba; Badr, Therese; Sepetdjian, Elizabeth; Al Rashidi, Mariam; Saliba, Najat; Shihadeh, Alan

2009-01-01

363

Comparison of carcinogen, carbon monoxide, and ultrafine particle emissions from narghile waterpipe and cigarette smoking: Sidestream smoke measurements and assessment of second-hand smoke emission factors  

NASA Astrophysics Data System (ADS)

The lack of scientific evidence on the constituents, properties, and health effects of second-hand waterpipe smoke has fueled controversy over whether public smoking bans should include the waterpipe. The purpose of this study was to investigate and compare emissions of ultrafine particles (UFP, <100 nm), carcinogenic polyaromatic hydrocarbons (PAH), volatile aldehydes, and carbon monoxide (CO) for cigarettes and narghile (shisha, hookah) waterpipes. These smoke constituents are associated with a variety of cancers, and heart and pulmonary diseases, and span the volatility range found in tobacco smoke. Sidestream cigarette and waterpipe smoke was captured and aged in a 1 m 3 Teflon-coated chamber operating at 1.5 air changes per hour (ACH). The chamber was characterized for particle mass and number surface deposition rates. UFP and CO concentrations were measured online using a fast particle spectrometer (TSI 3090 Engine Exhaust Particle Sizer), and an indoor air quality monitor. Particulate PAH and gaseous volatile aldehydes were captured on glass fiber filters and DNPH-coated SPE cartridges, respectively, and analyzed off-line using GC-MS and HPLC-MS. PAH compounds quantified were the 5- and 6-ring compounds of the EPA priority list. Measured aldehydes consisted of formaldehyde, acetaldehyde, acrolein, methacrolein, and propionaldehyde. We found that a single waterpipe use session emits in the sidestream smoke approximately four times the carcinogenic PAH, four times the volatile aldehydes, and 30 times the CO of a single cigarette. Accounting for exhaled mainstream smoke, and given a habitual smoker smoking rate of 2 cigarettes per hour, during a typical one-hour waterpipe use session a waterpipe smoker likely generates ambient carcinogens and toxicants equivalent to 2-10 cigarette smokers, depending on the compound in question. There is therefore good reason to include waterpipe tobacco smoking in public smoking bans.

Daher, Nancy; Saleh, Rawad; Jaroudi, Ezzat; Sheheitli, Hiba; Badr, Thérèse; Sepetdjian, Elizabeth; Al Rashidi, Mariam; Saliba, Najat; Shihadeh, Alan

2010-01-01

364

Comparison of carcinogen, carbon monoxide, and ultrafine particle emissions from narghile waterpipe and cigarette smoking: Sidestream smoke measurements and assessment of second-hand smoke emission factors.  

PubMed

The lack of scientific evidence on the constituents, properties, and health effects of second-hand waterpipe smoke has fueled controversy over whether public smoking bans should include the waterpipe. The purpose of this study was to investigate and compare emissions of ultrafine particles (UFP, <100 nm), carcinogenic polyaromatic hydrocarbons (PAH), volatile aldehydes, and carbon monoxide (CO) for cigarettes and narghile (shisha, hookah) waterpipes. These smoke constituents are associated with a variety of cancers, and heart and pulmonary diseases, and span the volatility range found in tobacco smoke.Sidestream cigarette and waterpipe smoke was captured and aged in a 1 m(3) Teflon-coated chamber operating at 1.5 air changes per hour (ACH). The chamber was characterized for particle mass and number surface deposition rates. UFP and CO concentrations were measured online using a fast particle spectrometer (TSI 3090 Engine Exhaust Particle Sizer), and an indoor air quality monitor. Particulate PAH and gaseous volatile aldehydes were captured on glass fiber filters and DNPH-coated SPE cartridges, respectively, and analyzed off-line using GC-MS and HPLC-MS. PAH compounds quantified were the 5- and 6-ring compounds of the EPA priority list. Measured aldehydes consisted of formaldehyde, acetaldehyde, acrolein, methacrolein, and propionaldehyde.We found that a single waterpipe use session emits in the sidestream smoke approximately four times the carcinogenic PAH, four times the volatile aldehydes, and 30 times the CO of a single cigarette. Accounting for exhaled mainstream smoke, and given a habitual smoker smoking rate of 2 cigarettes per hour, during a typical one-hour waterpipe use session a waterpipe smoker likely generates ambient carcinogens and toxicants equivalent to 2-10 cigarette smokers, depending on the compound in question. There is therefore good reason to include waterpipe tobacco smoking in public smoking bans. PMID:20161525

Daher, Nancy; Saleh, Rawad; Jaroudi, Ezzat; Sheheitli, Hiba; Badr, Thérèse; Sepetdjian, Elizabeth; Al Rashidi, Mariam; Saliba, Najat; Shihadeh, Alan

2010-01-01

365

FINE PARTICLE CHARGING DEVELOPMENT  

EPA Science Inventory

The report gives results of theoretical and experimental investigations into the changing of fine particles by unipolar ions in an electric field, and evaluation of a specially designed small pilot-scale (600-1000 acfm) precharging device. Following an extensive review of the lit...

366

Consequences of developmental exposure to concentrated ambient ultrafine particle air pollution combined with the adult paraquat and maneb model of the Parkinson's disease phenotype in male mice.  

PubMed

Current evidence suggests suceptibility of both the substantia nigra and striatum to exposure to components of air pollution. Further, air pollution has been associated with increased risk of PD diagnsosis in humans or PD-like pathology in animals. This study examined whether exposure of mice to concentrated ambient ultrafine particles (CAPS; <100nm diameter) during the first two weeks of life would alter susceptibility to induction of the Parkinson's disease phenyotype (PDP) in a pesticide-based paraquat and maneb (PQ+MB) model during adulthood utilizing i.p. injections of 10mg/kg PQ and 30mg/kg MB 2× per week for 6 weeks. Evidence of CAPS-induced enhancement of the PQ+MB PDP was limited primarily to delayed recovery of locomotor activity 24 post-injection of PQ+MB that could be related to alterations in striatal GABA inhibitory function. Absence of more extensive interactions might also reflect the finding that CAPS and PQ+MB appeared to differentially target the nigrostriatal dopamine and amino acid systems, with CAPS impacting striatum and PQ+MB impacting dopamine-glutamate function in midbrain; both CAPS and PQ+MB elevated glutamate levels in these specific regions, consistent with potential excitotoxicity. These findings demonstrate the ability of postnatal CAPS to produce locomotor dysfunction and dopaminergic and glutamateric changes, independent of PQ+MB, in brain regions involved in the PDP. PMID:24486957

Allen, Joshua L; Liu, Xiufang; Weston, Douglas; Conrad, Katherine; Oberdörster, Günter; Cory-Slechta, Deborah A

2014-03-01

367

Nano-porous TiO2 layer using ultrafine nano-particles for the blocking layer in dye-sensitized solar cells.  

PubMed

A nano-porous TiO2 layer was produced by spray-deposition using ultrafine anatase nano-particles for the blocking layer for the dye-sensitized solar cells (DSCs). The microstructure and the electrochemical properties of the spray-deposited TiO2 layer were examined. The results of electrochemical properties showed that the spray-deposited TiO2 layer was capable to suppress the I3- ions diffusion to FTO substrate, reducing the electron recombination between the electrons on FTO substrate and I3- ions in electrolyte. In addition, the connection between TiO2 film and FTO substrate was improved by the TiO2 layer. Therefore, the short circuit current density and thereby the photo-to-electric energy conversion efficiency were improved by this blocking layer. The blocking effect of the porous layer was attributed to both the complicated pore structure of the spray-deposited layer and the enhanced connections between TiO2 film and FTO substrate. The low temperature characteristic of spray deposition approach indicates that it is suitable to the flexible-based DSCs. PMID:24734697

Yao, Hai-Long; Ma, Jun-Hua; Yang, Guan-Jun; He, Xue-Long; Fan, Sheng-Qiang; Li, Cheng-Xin; Li, Chang-Jiu

2014-04-01

368

X-Ray Diffraction Study on Ultrafine Particles of Ag-Cu Alloys Prepared by “Hydrogen Plasma-Metal” Reaction Method  

NASA Astrophysics Data System (ADS)

A series of ultrafine particles (UFP) in AgxCu100-x alloys was prepared by the “hydrogen plasma-metal” reaction method with changing composition xb of bulk parent alloys. The changes in diffraction profiles and lattice constants on xb were investigated by X-ray diffraction and least-squares pattern fitting methods. On the Cu-rich side (xb<50), the UFP was composed of three metastable phases: Cu-rich 1 phase (x{=}6.1˜5.3), Cu-rich 2 phase (x˜12.2) and Ag-rich phase (x{=}94.8˜91.0). In these, the solubility of Ag in the Cu-rich 2 phase was about 2.5 times as large as the maximum value (x{=}4.9) at the eutectic temperature of the equilibrium phase diagram. On the Ag-rich side together with xb{=}50, the UFP was composed of Cu-rich 1 phase (x˜5.3) and Ag-rich phase (x˜91.7) except for xb{=}90. The total concentration of Ag in the UFP noticeably deviated positively from xb.

Nakahigashi, Kiyotaka; Ishibashi, Hiroki; Minamigawa, Shinnosuke; Kogachi, Mineo

1992-07-01

369

Co-formation of hydroperoxides and ultra-fine particles during the reactions of ozone with a complex VOC mixture under simulated indoor conditions  

NASA Astrophysics Data System (ADS)

In this study we examined the co-formation of hydrogen peroxide and other hydroperoxides (collectively presented as H 2O 2*) as well as submicron particles, including ultra-fine particles (UFP), resulting from the reactions of ozone (O 3) with a complex mixture of volatile organic compounds (VOCs) under simulated indoor conditions. The VOC mixture contained 23 compounds, including two terpenes ( d-limonene and ?-pinene), two unsaturated alkenes (1-decene and 1-octene), and 19 other saturated organic compounds. These compounds are commonly found in indoor air but their concentrations were higher than typical indoor levels. When O 3 was added to a 25-m 3 controlled environmental facility (CEF) containing the 23 VOC mixture, both H 2O 2* and submicron particles were formed. The 2-h average concentration of H 2O 2* was 1.89±0.30 ppb, and the average total particle number concentration was 46,000±12,000 particles cm -3. A small increase of UFP (0.02-0.1 ?m) occurred 5 min after the O 3 addition (17 min after the VOC addition) and a sharp increase of UFP occurred 13 min after the O 3 addition, suggesting homogeneous nucleation. The delayed onset of this event might reflect the time required to achieve saturated concentrations of the condensable organics. When the 2 terpenes were removed from the O 3/23 VOCs mixture, no H 2O 2* or particles were formed, indicating that the reactions of O 3 with the two terpenes were the key processes contributing to the formation of H 2O 2* and submicron particles in the O 3/23 VOCs system. The present study confirmed the findings of a previous study carried out in a real-world office and generated new findings regarding co-formation of UFP. Through a comparative analysis of H 2O 2* yields under different reaction conditions, this study demonstrates that VOCs co-present with the terpenes and O 3 may play a role in producing H 2O 2*.

Fan, Zhihua; Weschler, Charles J.; Han, In-Kyu; Zhang, Junfeng (Jim)

370

The effects of leaf area density variation on the collection efficiency of black carbon in the size range of ultrafine particles (UFP)  

NASA Astrophysics Data System (ADS)

Black carbon is mainly produced in the ultra-fine particle (UFP) size range of 10-100 nm from combustion processes and is now receiving significant attention given its role in global and regional climate change, cloud physics, human health and respiratory related diseases. Likewise, the role of vegetated surfaces in removing UFP is drawing increased attention, prompting interest in the relationship between leaf area density and UFP collection efficiency. Here, carbonaceous particles, mainly black carbon, were generated by burning candles during "sooting burn" to explore the effects of leaf area density (LAD) variation on the collection efficiency of black carbon in the UFP size range. Three scenarios were explored in a wind tunnel: (1) Juniperus Chinensis branches that are uniformly distributed within the test section; (2) LAD that is linearly increasing with downwind distance and (3) LAD that is decreasing with downwind distance. The total leaf area index (LAI) was maintained constant in all three cases. Particle concentrations were measured at multiple locations within the vegetated volume for a range of sizes of UFP (12.6-102 nm) using Scanning Mobility Particle Sizer (SMPS). The measured concentration can be used to evaluate the performance of a size-resolving model that couples the turbulent flow field and the collection efficiency for the variable LAD. The model assumes that (i) the mean longitudinal momentum balance is controlled only by the interplay between drag force and the pressure gradient, and (ii) the dominant collection mechanism for UFP is Brownian diffusion. Hence, other collection mechanisms such as inertial impaction, interception and phoretic effects are negligible. Good agreement was found between the model calculations of the UFP collection efficiency by the vegetation and the wind tunnel measurements for all three cases and across a wide range of wind speeds and particle size. It was shown that variations in leaf area density lead to a modification in the mean pressure gradient, resulting in an adjustment in the drag coefficient via the mean momentum balance. Once this adjustment is accounted for, the over-all particle collection efficiency is governed by the integrated LAD.

Huang, C.; Lin, M.; Khlystov, A.; Katul, G. G.

2012-12-01

371

Investigations of percutaneous uptake of ultrafine TiO 2 particles at the high energy ion nanoprobe LIPSION  

NASA Astrophysics Data System (ADS)

Micronised TiO 2 particles with a diameter of about 15 nm are used in sunscreens as physical UV filter. Due to the small particle size it may be supposed that TiO 2 particles can pass through the uppermost horny skin layer ( stratum corneum) via intercellular channels and penetrate into deeper vital skin layers. Accumulations of TiO 2 particles in the skin can decrease the threshold for allergies of the immune system or cause allergic reactions directly. Spatially resolved ion beam analysis (PIXE, RBS, STIM and secondary electron imaging) was carried out on freeze-dried cross-sections of biopsies of pig skin, on which four different formulations containing TiO 2 particles were applied. The investigations were carried out at the high energy ion nanoprobe LIPSION in Leipzig with a 2.25 MeV proton beam, which was focused to a diameter of 1 ?m. The analysis concentrated on the penetration depth and on pathways of the TiO 2 particles into the skin. In these measurements a penetration of TiO 2 particles through the s. corneum into the underlying stratum granulosum via intercellular space was found. Hair follicles do not seem to be important penetration pathways because no TiO 2 was detected inside. The TiO 2 particle concentration in the stratum spinosum was below the minimum detection limit of about 1 particle/?m 2. These findings show the importance of coating the TiO 2 particles in order to prevent damage of RNA and DNA of skin cells by photocatalytic reactions of the penetrated particles caused by absorption of UV light.

Menzel, F.; Reinert, T.; Vogt, J.; Butz, T.

2004-06-01

372

Miniature Pipe Bundle Heat Exchanger for Thermophoretic Deposition of Ultrafine Soot Aerosol Particles at High Flow Velocities  

Microsoft Academic Search

The deposition of submicrometer soot aerosol particles in a miniature pipe bundle heat exchanger system has been investigated under conditions characteristic for combustion exhaust from diesel engines and oil or biomass burning processes. The system has been characterized for a wide range of aerosol inlet temperatures (390–510 K) and flow velocities (1–4 m s), and particle deposition efficiencies up to

A. Messerer; R. Niessner; U. Pöschl

2004-01-01

373

Indoor/outdoor relationships of quasi-ultrafine, accumulation and coarse mode particles in school environments in Barcelona: chemical composition and sources  

NASA Astrophysics Data System (ADS)

The mass concentration, chemical composition and sources of quasi-ultrafine (quasi-UFP, PM0.25), accumulation (PM0.25-2.5) and coarse mode (PM2.5-10) particles were determined in indoor and outdoor air at 39 schools in Barcelona (Spain). Quasi-UFP mass concentrations measured (25.6 ?g m-3 outdoors, 23.4 ?g m-3 indoors) are significantly higher than those reported in other studies, and characterised by higher carbonaceous and mineral matter contents and a lower proportion of secondary inorganic ions. Results suggest that quasi-UFPs in Barcelona are affected by local sources in the schools, mainly human activity (e.g. organic material from textiles, etc.; contributing 23-46% to total quasi-UFP mass) and playgrounds (in the form of mineral matter, contributing about 9% to the quasi-UFP mass). The particle size distribution of toxicologically relevant metals and major aerosol components was characterised, displaying bimodal size distributions for most elements and components, and a unimodal distribution for inorganic salts (ammonium nitrate and sulphate) and elemental carbon (EC). Regarding metals, Ni and Cr were partitioned mainly in quasi-UFPs and could thus be of interest for epidemiological studies, given their high redox properties. Children exposure to quasi-UFP mass and chemical species was assessed by comparing the concentrations measured at urban background and traffic areas schools. Finally, three main indoor sources across all size fractions were identified by assessing indoor/outdoor ratios (I/O) of PM species used as their tracers: human activity (organic material), cleaning products, paints and plastics (Cl- source), and a metallic mixed source (comprising combinations of Cu, Zn, Co, Cd, Pb, As, V and Cr).

Viana, M.; Rivas, I.; Querol, X.; Alastuey, A.; Sunyer, J.; Álvarez-Pedrerol, M.; Bouso, L.; Sioutas, C.

2013-12-01

374

Exposure to fine and ultrafine particles from secondhand smoke in public places before and after the smoking ban, Italy 2005  

Microsoft Academic Search

Results: In the post-law period, PM2.5 decreased significantly from a mean concentration of 119.3 mg\\/m 3 to 38.2 mg\\/m3 after 3 months (p,0.005), and then to 43.3 mg\\/m3 a year later (p,0.01). The UFP concentrations also decreased significantly from 76 956 particles\\/cm3 to 38 079 particles\\/cm3 (p,0.0001) and then to 51 692 particles\\/cm3 (p,0.01). Similarly, the concentration of urinary cotinine

Pasquale Valente; Francesco Forastiere; Antonella Bacosi; Giorgio Cattani; Simonetta Di Carlo; Monica Ferri; Irene Figa; Achille Marconi; Luigi Paoletti; Carlo Perucci; Piergiorgio Zuccaro

2010-01-01

375

Comprehensive Characterization Of Ultrafine Particulate Emission From 2007 Diesel Engines: PM Size Distribution, Loading And Indidividual Particle Size And Composition.  

NASA Astrophysics Data System (ADS)

The strong absorption of solar radiation by black carbon (BC) impacts the atmospheric radiative balance in a complex and significant manner. One of the most important sources of BC is vehicular emissions, of which diesel represents a significant fraction. To address this issue the EPA has issues new stringent regulations that will be in effect in 2007, limiting the amount of particulate mass that can be emitted by diesel engines. The new engines are equipped with aftertreatments that reduce PM emissions to the point, where filter measurements are subject to significant artifacts and characterization by other techniques presents new challenges. We will present the results of the multidisciplinary study conducted at the Cummins Technical Center in which a suite of instruments was deployed to yield comprehensive, temporally resolved information on the diesel exhaust particle loadings and properties in real-time: Particle size distributions were measured by Engine Exhaust Particle Sizer (EEPS) and Scanning Mobility Particle Sizer (SMPS). Total particle diameter concentration was obtained using Electrical Aerosol Detector (EAD). Laser Induced Incandescence and photoacoustic techniques were used to monitor the PM soot content. Single Particle Laser Ablation Time-of- flight Mass Spectrometer (SPLAT) provided the aerodynamic diameter and chemical composition of individual diesel exhaust particles. Measurements were conducted on a number of heavy duty diesel engines operated under variety of operating conditions, including FTP transient cycles, ramped-modal cycles and steady states runs. We have also characterized PM emissions during diesel particulate filter regeneration cycles. We will present a comparison of PM characteristics observed during identical cycles, but with and without the use of aftertreatment. A total of approximately 100,000 individual particles were sized and their composition characterized by SPLAT. The aerodynamic size distributions of the characterized particles were between 50 and 300 nm, depending on engine operating conditions and particle composition. We will show that while the drastically reduced diesel PM emissions often render the PM filter measurements inadequate due to organic vapor artifacts SPLAT demonstrated its capability to provide real-time information on size and composition of individual diesel exhaust particles as function of engine operating conditions with better than 1 minute resolution.

Zelenyuk, A.; Cuadra-Rodriguez, L. A.; Imre, D.; Shimpi, S.; Warey, A.

2006-12-01

376

The Ultrafine Mineralogy of a Molten Interplanetary Dust Particle as an Example of the Quench Regime of Atmospheric Entry Heating  

NASA Technical Reports Server (NTRS)

Melting and degassing of interplanetary dust particle L2005B22 at approx. 1200 C was due to flash heating during atmospheric entry. Preservation of the porous particle texture supports rapid quenching from the peak heating temperature whereby olivine and pyroxene nanocrystals (3 nm-26 nm) show partial devitrification of the quenched melt at T approx. = 450 C - 740 C. The implied ultrahigh cooling rates are calculated at approx. 105 C/h-106 C/h, which is consistent with quench rates inferred from the temperature-time profiles based on atmospheric entry heating models. A vesicular rim on a nonstoichiometric relic forsterite grain in this particle represents either evaporative magnesium loss during flash heating or thermally annealed ion implantation texture.

Rietmeijer, Frans J. M.

1996-01-01

377

Particle Deposition in a Child Respiratory Tract Model: In Vivo Regional Deposition of Fine and Ultrafine Aerosols in Baboons  

PubMed Central

To relate exposure to adverse health effects, it is necessary to know where particles in the submicron range deposit in the respiratory tract. The possibly higher vulnerability of children requires specific inhalation studies. However, radio-aerosol deposition experiments involving children are rare because of ethical restrictions related to radiation exposure. Thus, an in vivo study was conducted using three baboons as a child respiratory tract model to assess regional deposition patterns (thoracic region vs. extrathoracic region) of radioactive polydisperse aerosols ([d16–d84], equal to [0.15 µm–0.5 µm], [0.25 µm–1 µm], or [1 µm–9 µm]). Results clearly demonstrated that aerosol deposition within the thoracic region and the extrathoraic region varied substantially according to particle size. High deposition in the extrathoracic region was observed for the [1 µm–9 µm] aerosol (72%±17%). The [0.15 µm–0.5 µm] aerosol was associated almost exclusively with thoracic region deposition (84%±4%). Airborne particles in the range of [0.25 µm–1 µm] showed an intermediate deposition pattern, with 49%±8% in the extrathoracic region and 51%±8% in the thoracic region. Finally, comparison of baboon and human inhalation experiments for the [1 µm–9 µm] aerosol showed similar regional deposition, leading to the conclusion that regional deposition is species-independent for this airborne particle sizes.

Albuquerque-Silva, Iolanda; Vecellio, Laurent; Durand, Marc; Avet, John; Le Pennec, Deborah; de Monte, Michele; Montharu, Jerome; Diot, Patrice; Cottier, Michele; Dubois, Francis; Pourchez, Jeremie

2014-01-01

378

Particle deposition in a child respiratory tract model: in vivo regional deposition of fine and ultrafine aerosols in baboons.  

PubMed

To relate exposure to adverse health effects, it is necessary to know where particles in the submicron range deposit in the respiratory tract. The possibly higher vulnerability of children requires specific inhalation studies. However, radio-aerosol deposition experiments involving children are rare because of ethical restrictions related to radiation exposure. Thus, an in vivo study was conducted using three baboons as a child respiratory tract model to assess regional deposition patterns (thoracic region vs. extrathoracic region) of radioactive polydisperse aerosols ([d16-d84], equal to [0.15 µm-0.5 µm], [0.25 µm-1 µm], or [1 µm-9 µm]). Results clearly demonstrated that aerosol deposition within the thoracic region and the extrathoraic region varied substantially according to particle size. High deposition in the extrathoracic region was observed for the [1 µm-9 µm] aerosol (72%±17%). The [0.15 µm-0.5 µm] aerosol was associated almost exclusively with thoracic region deposition (84%±4%). Airborne particles in the range of [0.25 µm-1 µm] showed an intermediate deposition pattern, with 49%±8% in the extrathoracic region and 51%±8% in the thoracic region. Finally, comparison of baboon and human inhalation experiments for the [1 µm-9 µm] aerosol showed similar regional deposition, leading to the conclusion that regional deposition is species-independent for this airborne particle sizes. PMID:24787744

Albuquerque-Silva, Iolanda; Vecellio, Laurent; Durand, Marc; Avet, John; Le Pennec, Déborah; de Monte, Michèle; Montharu, Jérôme; Diot, Patrice; Cottier, Michèle; Dubois, Francis; Pourchez, Jérémie

2014-01-01

379

Development of the electroacoustic dewatering (EAD) process for fine/ultrafine coal: Second quarterly progress report period ending 31 March 1989  

SciTech Connect

Battelle, in cooperation with the Electric Power Research Institute (EPRI), Ashbrook-Simon-Hartley (ASH), Kaiser Engineers (KE), Lewis Corporation, and Prof. S.H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to a commercial belt filter press design that is used in many other applications. The EAD equipment is described. 2 figs.

Not Available

1989-04-18

380

A velocity map imaging photoelectron spectrometer for the study of ultrafine aerosols with a table-top VUV laser and Na-doping for particle sizing applied to dimethyl ether condensation  

NASA Astrophysics Data System (ADS)

We present a new experimental configuration for the study of size-dependent, angle-resolved photoelectron and photoion spectra of weakly bound ultrafine aerosol particles targeted at particle sizes below ~20 nm. It combines single photon ionization by a tunable, table-top vacuum ultraviolet laser at energies up to 18 eV with velocity map imaging detection and independent size determination of the aerosol particles using the Na-doping method. As an example, the size-dependence of the valence photoelectron spectrum of dimethyl ether clusters and ultrafine aerosols is investigated. Up to a mean particle diameter of ~3-4 nm, the first ionization energy (value at band maximum) decreases systematically (up to ~1 eV) and the corresponding band broadens systematically (up to a factor of ~3) with increasing aggregate size. Plateau values for band positions and bandwidths are reached beyond a diameter of ~3-4 nm. Experimental evidence for the dominance of the fast intermolecular proton transfer over monomer fragmentation reactions upon ionization is presented via photoion imaging.

Yoder, Bruce L.; West, Adam H. C.; Schläppi, Bernhard; Chasovskikh, Egor; Signorell, Ruth

2013-01-01

381

Ultrafine aerosol size distributions and sulfuric acid vapor pressures: Implications for new particle formation in the atmosphere. Year 2 progress report  

SciTech Connect

This project has two components: (1) measurement of H{sub 2}SO{sub 4} vapor pressures in air under temperature/relative humidity conditions similar to atmospheric, and (2) measurement of ultrafine aerosol size distributions. During Year 2, more effort was put on size distribution measurements. 4 figs.

McMurry, P.H.

1993-07-01

382

An investigation on dewatering kinetics of ultrafine coal  

Microsoft Academic Search

Ultrafine coal dewatering is of great importance to the coal industry due to its impacts on the handling and utilization characteristics of coal products. Commercially available filtration techniques are either ineffective or costly for dewatering of ultrafine coal to the desired moisture level of about 20%. Considerable efforts have been devoted to understanding the dewatering process and developing new technologies

D. Tao; B. K. Parekh; J. T. Liu; S. Chen

2003-01-01

383

Novel synthesis of substoichiometric ultrafine titanium carbide  

Microsoft Academic Search

Ultrafine titanium carbide particles were synthesized by liquid-magnesium reduction of vaporized TiCl4+CCl4 solution. Fine TiC particles were produced by the reaction of released Ti and C atoms, and after reduction process vacuum was used to remove the residual phases of MgCl2 and excess Mg. Fixed and free carbon were measured in products synthesized with various parameters as well as stoichiometry

D. W. Lee; S. V. Alexandrovskii; B. K. Kim

2004-01-01

384

Fine and ultrafine particles of the diet: influence on the mucosal immune response and association with Crohn's disease.  

PubMed

Crohn's disease is a modern Western disease characterised by transmural inflammation of the gastrointestinal tract. It is of unknown aetiology, but evidence suggests that it results from a combination of genetic predisposition and environmental factors. Bacterial-sized microparticles (0.1-1.0 microm) are potent adjuvants in model antigen-mediated immune responses and are increasingly associated with disease. Microparticles of TiO2 and aluminosilicate accumulate in macrophages of human gut-associated lymphoid tissue where the earliest signs of lesions in Crohn's disease are observed. Dietary microparticles are of endogenous or exogenous origin. Endogenous microparticles dominate and are calcium phosphate (most probably hydroxyapatite), which precipitates in the lumen of the mid-distal gastrointestinal tract due to secretion of Ca and phosphate in the succus entericus. Exogenous dietary microparticles are contaminants (soil and/or dust) and food additives. TiO2, for example, is a food colourant, and aluminosilicates are anti-caking agents, although some aluminosilicates occur as natural contaminants. Food additives alone account for ingestion of approximately 10(12) particles/person per d. Possible mechanisms for the role of exogenous and endogenous dietary microparticles in promoting toleragenic or immune responses of gastrointestinal mucosal phagocytosis are discussed. In a double-blind randomised pilot study we have shown that a diet low in Ca and exogenous microparticles appears to alleviate the symptoms of ileal Crohn's disease, with a significant (P= 0.002) improvement in the Crohn's disease activity index. A multi-centre trial and further mechanistic studies at the cellular level are underway. PMID:12002786

Lomer, Miranda C E; Thompson, Richard P H; Powell, Jonathan J

2002-02-01

385

Ultrafine particles from diesel vehicle emissions at different driving cycles induce differential vascular pro-inflammatory responses: Implication of chemical components and NF-?B signaling  

PubMed Central

Background Epidemiological evidence supports the association between exposure to ambient particulate matter (PM) and cardiovascular diseases. Chronic exposure to ultrafine particles (UFP; Dp <100 nm) is reported to promote atherosclerosis in ApoE knockout mice. Atherogenesis-prone factors induce endothelial dysfunction that contributes to the initiation and progression of atherosclerosis. We previously demonstrated that UFP induced oxidative stress via c-Jun N-terminal Kinases (JNK) activation in endothelial cells. In this study, we investigated pro-inflammatory responses of human aortic endothelial cells (HAEC) exposed to UFP emitted from a diesel truck under an idling mode (UFP1) and an urban dynamometer driving schedule (UFP2), respectively. We hypothesize that UFP1 and UFP2 with distinct chemical compositions induce differential pro-inflammatory responses in endothelial cells. Results UFP2 contained a higher level of redox active organic compounds and metals on a per PM mass basis than UFP1. While both UFP1 and UFP2 induced superoxide production and up-regulated stress response genes such as heme oxygenease-1 (HO-1), OKL38, and tissue factor (TF), only UFP2 induced the expression of pro-inflammatory genes such as IL-8 (2.8 ± 0.3-fold), MCP-1 (3.9 ± 0.4-fold), and VCAM (6.5 ± 1.1-fold) (n = 3, P < 0.05). UFP2-exposed HAEC also bound to a higher number of monocytes than UFP1-exposed HAEC (Control = 70 ± 7.5, UFP1 = 106.7 ± 12.5, UFP2 = 137.0 ± 8.0, n = 3, P < 0.05). Adenovirus NF-?B Luciferase reporter assays revealed that UFP2, but not UFP1, significantly induced NF-?B activities. NF-?B inhibitor, CAY10512, significantly abrogated UFP2-induced pro-inflammatory gene expression and monocyte binding. Conclusion While UFP1 induced higher level of oxidative stress and stress response gene expression, only UFP2, with higher levels of redox active organic compounds and metals, induced pro-inflammatory responses via NF-?B signaling. Thus, UFP with distinct chemical compositions caused differential response patterns in endothelial cells.

2010-01-01

386

Ultrafine ash aerosols from coal combustion: Characterization and health effects  

SciTech Connect

Ultrafine coal fly-ash particles withdiameters less than 0.5 {mu}m typically comprise less than 1% of the total fly-ash mass. This paper reports research focused on both characterization and health effects of primary ultrafine coal ash aerosols alone. Ultrafine, fine, and coarse ash particles were segregated and collected from a coal burned in a 20 kW laboratory combustor and two additional coals burned in an externally heated drop tube furnace. Extracted samples from both combustors were characterized by transmission electron microscopy (TEM), wavelength dispersive X-ray fluorescence(WD-XRF) spectroscopy, Moessbauer spectroscopy, and X-ray absorption fine structure (XAFS) spectroscopy. Pulmonary inflammation was characterized by albumin concentrations in mouse lung lavage fluid after instillation of collected particles in saline solutions and a single direct inhalation exposure. Results indicate that coal ultrafine ash sometimes contains significant amounts of carbon, probably soot originating from coal tar volatiles, depending on coal type and combustion device. Surprisingly, XAFS results revealed the presence of chromium and thiophenic sulfur in the ultrafine ash particles. The instillation results sugge