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1

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

2

Personal exposure to ultrafine particles  

Microsoft Academic Search

Personal exposure to ultrafine particles (UFP) can occur while people are cooking, driving, smoking, operating small appliances such as hair dryers, or eating out in restaurants. These exposures can often be higher than outdoor concentrations. For 3 years, portable monitors were employed in homes, cars, and restaurants. More than 300 measurement periods in several homes were documented, along with 25

Lance Wallace; Wayne Ott

2011-01-01

3

Ultrafine particle emissions from waterpipes  

PubMed Central

Objectives Ultrafine particle emissions from waterpipes and their impact on human health have not been extensively studied. The aim of this study was to characterise the inhalation pattern of waterpipe smokers, and (a) construct apparatus to simulate waterpipe smoking in the laboratory, and (b) characterise mainstream emissions from waterpipes under different smoking conditions. Methods Real life waterpipe smoking patterns were first measured with a spirometer. The average smoking pattern was then mechanically simulated in apparatus. Total particle number concentrations were determined with a condensation particle counter (CPC) for particles between 0.02??m and 1??m (P?Trak UPC, Model 8525, TSI) and the particle size fraction was determined with a differential mobility analyser (DMA) for particles from 0.01??m to 0.5??m. This instrument was coupled with a laser particle spectrometer for particles between 0.35??m and 10??m (Wide Range Particle Spectrometer, Model 1000XP, MSC Corp). Carbon monoxide levels were determined with an electrochemical sensor (Q?Trak monitor, Model 8554, TSI). Results The tidal volume of an average waterpipe breath of 5?seconds was found to be 1 (SD 0.47) litre. The intervals between breaths on average were 25.5 (SD 10.2) seconds. Particle number concentrations of ultrafine particles in mainstream smoke during waterpipe smoking ranged up to 70×109 particles per litre. The median diameter of the particles in a full smoking set with charcoal, tobacco and water was 0.04??m. Smoke from the heated tobacco contributed to particles in the size range between 0.01??m and 0.2??m. The glowing piece of charcoal only contributed to particles smaller than 0.05??m. Conclusions Waterpipe smoking emits large amounts of ultrafine particles. With regard to particle emissions, smoking waterpipes may carry similar health risks to smoking cigarettes.

Monn, Ch; Kindler, Ph; Meile, A; Brandli, O

2007-01-01

4

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

5

Efficiency of cloud condensation nuclei formation from ultrafine particles  

Microsoft Academic Search

Atmospheric cloud condensation nuclei (CCN) concentrations are a key uncertainty in the assessment of the effect of anthropogenic aerosol on clouds and climate. The ability of new ultrafine particles to grow to become CCN varies throughout the atmosphere and must be understood in order to understand CCN formation. We have developed the Probability of Ultrafine particle Growth (PUG) model to

J. R. Pierce; P. J. Adams

2007-01-01

6

Pulmonary effects of inhaled ultrafine particles  

Microsoft Academic Search

Introduction and Objectives: Recent epidemiological studies have shown an association between increased particulate urban air pollution and adverse health\\u000a effects on susceptible parts of the population, in particular the elderly with pre-existing respiratory and cardiovascular\\u000a diseases. Urban particles consist of three modes: ultrafine particles, accumulation mode particles (which together form the\\u000a fine particle mode) and coarse mode particles. Ultrafine particles

Günter Oberdörster

2000-01-01

7

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

PubMed

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. PMID:23502512

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

2013-03-15

8

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

9

Development of a base set of toxicity tests using ultrafine TiO 2 particles as a component of nanoparticle risk management  

Microsoft Academic Search

The development of a risk management system for nanoscale or ultrafine particle-types requires a base set of hazard data. Assessing risk is a function of hazard and exposure data. Previously, we have suggested “parallel tracks” as a strategy for conducting nanoparticle research. On the one hand, mechanistic studies on “representative” nanoparticles could be supported by governmental agencies. Alternatively, with regard

David B. Warheit; Robert A. Hoke; Carol Finlay; E. Maria Donner; Kenneth L. Reed; Christie M. Sayes

2007-01-01

10

Exposure to Ultrafine Particles in Urban Centres  

Microsoft Academic Search

\\u000a Ultrafine particles (UFP: particles with diameters less than 100 nm) can originate from anthropogenic sources such as fossil\\u000a fuel combustion, or naturally through nucleation of sulphuric acid, water and ammonia molecules. These particles can be further\\u000a transformed through condensation, evaporation and coagulation processes that affect their number, size and composition. The\\u000a properties of UFP from vehicle emissions depend on the vehicle

Kelly Sabaliauskas; Greg Evans

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

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

13

Unipolar ion emission enhances respiratory protection against fine and ultrafine particles  

Microsoft Academic Search

We developed a novel concept that allows to considerably improve the performance of conventionally used filtering-facepiece respirators against fine and ultrafine aerosols including airborne viral and bacterial agents. The concept is based on the continuous emission of unipolar ions. The effect was evaluated through the real-time monitoring of the concentration and size distribution of fine and ultrafine aerosol particles. The

Byung Uk Lee; Mikhail Yermakov; Sergey A. Grinshpun

2004-01-01

14

Structural development in ultrafine particles of zirconia produced from sol-gel  

SciTech Connect

The pH of the solution that hydrous zirconia is precipitated from appears to define the crystal structure formed after calcination of the material at 400-600{degree}C. A metastable tetragonal structure was obtained for either low (less than about 5) or high (greater than about 13) pH. The tetragonal phase formed at high pH is much more stable than that obtained at a low pH at a calcination temperature of 500{degree}C. Detailed structural studies were undertaken using transmission electron microscopy, X-ray diffraction and BET surface area. The results obtained from these analyses do not support the crystallite size theory, which states that the tetragonal particles of less than 300 {angstrom} are stabilized against the t {yields} m transformation. It was observed that the time taken to attain the final pH of the solution in contact with the precipitate in the pH range 7-11, plays a dominant role in determining the crystal structure of the zirconium oxide after calcination at 500{degree}C. The dependence of the crystal structure on the rate of precipitation is observed only in the pH range 7-11. Rapid precipitation in this pH range yields predominantly monoclinic zirconia, whereas slow (8 hours) precipitation produces the tetragonal phase. At a pH of approximately 13.0, only the tetragonal phase is formed from both slowly and rapidly precipitated hydrous oxide. The results indicate that both the pH of the supernatant liquid and the time taken to attain this pH play dominant roles in determining the crystal structure of zirconia formed after calcination of the hydrous oxide. The factors that determine the crystal phase are therefore imparted in a mechanism of precipitation that depends upon the pH, and it is inferred that it is the hydroxyl concentration that is the dominant factor.

Srinivasan, R.

1989-01-01

15

Characterizing and predicting ultrafine particle counts in Canadian classrooms during the winter months: Model development and evaluation  

SciTech Connect

School classrooms are potentially important micro-environments for childhood exposures owing to the large amount of time children spend in these locations. While a number of airborne contaminants may be present in schools, to date few studies have examined ultrafine particle (0.02-1 {mu}m) (UFP) levels in classrooms. In this study, our objective was to characterize UFP counts (cm{sup -3}) in classrooms during the winter months and to develop a model to predict such exposures based on ambient weather conditions and outdoor UFPs, as well as classroom characteristics such as size, temperature, relative humidity, and carbon dioxide levels. In total, UFP count data were collected on 60 occasions in 37 occupied classrooms at one elementary school and one secondary school in Pembroke, Ontario. On average, outdoor UFP levels exceeded indoor measures by 8989 cm{sup -3} (95% confidence interval (CI): 6382, 11 596), and classroom UFP counts were similar at both schools with a combined average of 5017 cm{sup -3} (95% CI: 4300, 5734). Of the variables examined only wind speed and outdoor UFPs were important determinants of classrooms UFP levels. Specifically, each 10 km/h increase in wind speed corresponded to an 1873 cm{sup -3} (95% CI: 825, 2920) decrease in classroom UFP counts, and each 10 000 cm{sup -3} increase in outdoor UFPs corresponded to a 1550 cm{sup -3} (95% CI: 930, 2171) increase in classroom UFP levels. However, high correlations between these two predictors meant that the independent effects of wind speed and outdoor UFPs could not be separated in multivariable models, and only outdoor UFP counts were included in the final predictive model. To evaluate model performance, classroom UFP counts were collected for 8 days at two new schools and compared to predicted values based on outdoor UFP measures. A moderate correlation was observed between measured and predicted classroom UFP counts (r=0.63) for both schools combined, but this relationship was not valid on days in which a strong indoor UFP source (electric kitchen stove) was active in schools. In general, our findings suggest that reasonable estimates of classroom UFP counts may be obtained from outdoor UFP data but that the accuracy of such estimates are limited in the presence of indoor UFP sources.

Weichenthal, Scott [Department of Epidemiology, Biostatistics and Occupational Health, Faculty of Medicine, McGill University, 1130 Pine Avenue West, Room B10, Charles Meredith House, Montreal, Que., H3A 1A3 (Canada)], E-mail: sweich@po-box.mcgill.ca; Dufresne, Andre; Infante-Rivard, Claire; Joseph, Lawrence [Department of Epidemiology, Biostatistics and Occupational Health, Faculty of Medicine, McGill University, 1130 Pine Avenue West, Room B10, Charles Meredith House, Montreal, Que., H3A 1A3 (Canada)

2008-03-15

16

Endocytosis of Ultrafine Particles by A549 Cells  

Microsoft Academic Search

Alveolar epithelium's capacity to ingest inhaled ultrafine parti- cles is not well characterized. The objectives of this study were to use an in vitro model of type II lung epithelium and evaluate the cells' ability to take up ultrafine particles (titanium dioxide (TiO 2 ), 50 nm diameter). The human epithelial cell line A549 was grown on aclar substrates and

Rebecca C. Stearns; Joseph D. Paulauskis; John J. Godleski

2001-01-01

17

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  

Microsoft Academic Search

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 VACES consists of three parallel sampling lines (concentrators), each operating at an intake flow rate of 110lmin?1. Coarse particles are concentrated using

Seongheon Kim; Peter A Jaques; Mingchih Chang; John R Froines; Constantinos Sioutas

2001-01-01

18

Development of a base set of toxicity tests using ultrafine TiO2 particles as a component of nanoparticle risk management.  

PubMed

The development of a risk management system for nanoscale or ultrafine particle-types requires a base set of hazard data. Assessing risk is a function of hazard and exposure data. Previously, we have suggested "parallel tracks" as a strategy for conducting nanoparticle research. On the one hand, mechanistic studies on "representative" nanoparticles could be supported by governmental agencies. Alternatively, with regard to commercial nanoparticles, the environmental, health and safety (EHS) framework would include a minimum base set of toxicity studies which should be supported by the companies that are developing nano-based products. The minimum base set could include the following criteria: substantial particle characterization, pulmonary toxicity studies, acute dermal toxicity and sensitization studies, acute oral and ocular toxicity studies, along with screening type genotoxicity, and aquatic toxicity studies. We report here the toxicity results of a base set of hazard tests on a set of newly developed, well-characterized, ultrafine TiO(2) (uf-TiO(2)) particle-types. In vivo pulmonary toxicity studies in rats demonstrated low inflammatory potential and lung tissue toxicity. Acute dermal irritation studies in rabbits and local lymph node assay results in mice indicated that uf-TiO(2) was not a skin irritant or dermal sensitizer. Acute oral toxicity studies demonstrated very low toxicity and uf-TiO(2) produced short-term and reversible ocular conjunctival redness in rabbits. Genotoxicity tests demonstrated that uf-TiO(2) was negative in both the bacterial reverse mutation test and in an in vitro mammalian chromosome aberration test with Chinese hamster ovary cells. The results of aquatic toxicity screening studies demonstrated that uf-TiO(2) exhibited low concern for aquatic hazard in unaerated, 48h, static acute tests using the water flea, Daphnia magna; exhibited low concern for aquatic hazard in unaerated, 96h, static acute tests using the rainbow trout, Oncorhynchus mykiss; and exhibited medium concern in a 72h acute test using the green algae Pseudokirchneriella subcapitata. To summarize the findings, the results of most of the studies demonstrated low hazard potential in mammals or aquatic species following acute exposures to the ultrafine TiO(2) particle-types tested in this program. PMID:17566673

Warheit, David B; Hoke, Robert A; Finlay, Carol; Donner, E Maria; Reed, Kenneth L; Sayes, Christie M

2007-04-27

19

Ultrafine particles at workplaces of a primary aluminium smelter.  

PubMed

The number concentration and size distribution of ultrafine particles in a Søderberg and a prebake potroom of an aluminium primary smelter have been measured using a scanning mobility particle spectrometer. The particle morphology was studied by transmission electron microscopy (TEM). The study shows the existence of elevated number concentrations of ultrafine particles in both potrooms. The main source of these particles is likely to be the process of anode changing. The ultrafine particles were measured directly at the source but could also be identified as episodes of high number concentrations in the general background air. Unlike the larger particles belonging to the 50-100 nm mode, the nanoparticle mode could not be detected in the TEM indicating that they may not be stable under the applied sampling conditions and/or the high vacuum in the instrument. PMID:16395469

Thomassen, Yngvar; Koch, Wolfgang; Dunkhorst, Wilhelm; Ellingsen, Dag G; Skaugset, Nils-Petter; Jordbekken, Lars; Arne Drabløs, Per; Weinbruch, Stephan

2005-12-07

20

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...

21

Adhesion of ultrafine particles—Energy absorption at contact  

Microsoft Academic Search

The mechanical product behaviour of cohesive ultrafine powders (d10?m) is characterized by insufficient flowability and large compressibility. Consequently, a comparatively large energy input is necessary to promote the non-rapid frictional shear flow in powder handling practice. The paper continues the new micromechanical philosophy demonstrated in the last publication [Tomas, J., 2007a. Adhesion of ultrafine particles—a micromechanical approach. Chemical Engineering Science

Jürgen Tomas

2007-01-01

22

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

23

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...

24

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

25

Calibration of a TSI Model 3025 Ultrafine Condensation Particle Counter  

Microsoft Academic Search

The registration efficiency of the TSI model 3025 ultra-fine condensation particle counter for Ag and NaCl particles of between 2 and 20 nm in diameter was determined. Taking into account the different shapes of the input aerosol size distributions entering the differential mobility analyzer (DMA) and the transfer function of the DMA, the counting efficiencies of condensation nucleus counters (CNC)

J. Kesten; A. Reineking; J. Porstendoerfer

1991-01-01

26

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

27

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...

28

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

29

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

30

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

31

Ultrafine aerosol particles in aircraft plumes: In situ observations  

Microsoft Academic Search

Measurements of ultrafine particles in the near field of the DLR research aircraft ATTAS using low (0.02 g\\/kg fuel) and high (2.7 g\\/kg) fuel sulfur contents (FSCs) are presented. Soot emissions of ~1015\\/kg show no significant dependence on FSC. Strong evidence is found that ~1\\/3 of the soot particles must be involved in ice nucleation in contrails, in addition to

F. P. Schröder; B. Kärcher; A. Petzold; R. Baumann; R. Busen; C. Hoell; U. Schumann

1998-01-01

32

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

33

Calibration of TSI model 3025 ultrafine condensation particle counter  

SciTech Connect

The registration efficiency of the TSI model 3025 ultrafine condensation particle counter for Ag and NaCl particles of between 2 and 20 nm in diameter was determined. Taking into account the different shapes of the input aerosol size distributions entering the differential mobility analyzer (DMA) and the transfer function of the DMA, the counting efficiencies of condensation nucleus counters (CNC) for monodisperse Ag and NaCl particles were estimated. In addition, the dependence of the CNC registration efficiency on the particle concentration was investigated.

Kesten, J.; Reineking, A.; Porstendoerfer, J. (Univ. of Goettingen (West Germany))

1991-01-01

34

Formation of ultrafine particles from impact-generated supercritical water  

Microsoft Academic Search

Shock-recovery experiments were performed targeting an olivine, iron, and water mixture to simulate a low-velocity ocean impact event. The maximum pressure in the sample container reached 20 GPa during the experiments. Ultrafine particles (UPs) of olivine and metal oxides were newly formed, even at pressures less than their vaporization pressure (150–200 GPa). Impedance-match and thermodynamic calculations suggest that supercritical water formed during

Yoshihiro Furukawa; Hiromoto Nakazawa; Toshimori Sekine; Takeshi Kakegawa

2007-01-01

35

Sampling methodologies and dosage assessment techniques for submicrometre and ultrafine virus aerosol particles  

Microsoft Academic Search

C.J. HOGAN JR, E.M. KETTLESON, M.-H. LEE, B. RAMASWAMI, L.T. ANGENENT AND P. BISWAS. 2005. Aims: The aerosolization and collection of submicrometre and ultrafine virus particles were studied with the objective of developing robust and accurate methodologies to study airborne viruses. Methods and Results: The collection efficiencies of three sampling devices used to sample airborne biological particles - the All

C. J. Hogan Jr; E. M. Kettleson; M.-H. Lee; B. Ramaswami; L. T. Angenent; P. Biswas

2005-01-01

36

Measurements of Ultrafine Particles and Other Vehicular Pollutants inside a Mobile Exposure System on Los Angeles Freeways  

Microsoft Academic Search

A mobile exposure and air pollution measurement system was developed and used for on-freeway ultrafine particle health effects studies. A nine-passenger van was modified with a high-efficiency particulate air (HEPA) filtration system that can deliver filtered or unfiltered air to an exposure chamber inside the van. State-of-the-art instruments were used to measure concentration and size distribution of fine and ultrafine

Yifang Zhu; David C. Fung; Nola Kennedy; William C. Hinds; Arantzazu Eiguren-Fernandez; Christian Dye; Kostantinos Eleftheriadis; Eleftheria Katsivela; Donald Martello; Natalie Pekney; Richard Anderson; Cliff Davidson; Philip Hopke; Eugene Kim; William Christensen; Nolan Mangelson; Delbert Eatough; Saqib Mukhtar; Atilla Mutlu; Sergio Capareda; Calvin Parnell; Andrew Rutter; Katy Hanford; Jaime Zwers; Anthony Perillo-Nicholas; James Schauer; Mark Olson; Paul Scott; Deborah Proctor; Yinka Afon; David Ervin; Li Wang; Praveen Kolar; James Kastner; Brian Herner; David Stieb; Richard Burnett; Marc Smith-Doiron; Orly Brion; Hwashin Shin; Vanita Economou; Rich Cook; Vlad Isakov; Jawad Touma; William Benjey; James Thurman; Ellen Kinnee; Darrell Ensley

2008-01-01

37

Numerical Simulation of Ultrafine Particle-Laden Cylinder Wake Flow with Coherent Structures  

Microsoft Academic Search

The phenomena of the wake flows containing ultrafine particles such as dust and pollutant in the atmosphere are usually observed downwind of the mountains and buildings. Different from the usually heavy particles, the ultrafine particles suspended in fluid undergo the processes of nucleation, growth and coagulation. Coherent structure in typical occurrence of the stretching of the Karman vortex street can

Changbin Wang; Shujie Zhi; Zhanhong Wan; Zhilin Sun; Hai Ding

2009-01-01

38

Deposition of inhaled charged ultrafine particles in a simple tracheal model  

Microsoft Academic Search

The deposition of ultrafine (d ? 200 nm) particles on airway surfaces is an important determinant of the radiation dose that results from inhalation of radon progeny. Diffusion is the dominant deposition mechanism for radon progeny since most of the alpha particle activity is on ultrafine particles. Freshly formed 218Po is rapidly neutralized but, there remains some charged fraction of

Beverly S. Cohen; Judy Q. Xiong; Bahman Asgharian; Lynda Ayres

1995-01-01

39

Water-Based Condensation Particle Counters for Environmental Monitoring of Ultrafine Particles  

Microsoft Academic Search

TSI Inc. (Shoreview, MN) has introduced three new water-based condensation particle counters (WCPCS) that were designed to detect airborne particles larger than 2.5 nm (model 3786), 5 nm (model 3785), and either 10 or 20 nm (model 3782). These WCPCs are well suited for real time, environmental monitoring of number concentration of airborne ultrafine particles. Their unique design incorporates the

Wei Liu; Stanley L. Kaufman; Brian L. Osmondson; Gilmore J. Sem; Frederick R. Quant; Derek R. Oberreit

2006-01-01

40

Exposure to airborne ultrafine particles from cooking in Portuguese homes.  

PubMed

Cooking was found to be a main source of submicrometer and ultrafine aerosols from gas combustion in stoves. Therefore, this study consisted of the determination of the alveolar deposited surface area due to aerosols resulting from common domestic cooking activities (boiling fish, vegetables, or pasta, and frying hamburgers and eggs). The concentration of ultrafine particles during the cooking events significantly increased from a baseline of 42.7 microm2/cm3 (increased to 72.9 microm2/cm3 due to gas burning) to a maximum of 890.3 microm2/cm3 measured during fish boiling in water and a maximum of 4500 microm2/cm3 during meat frying. This clearly shows that a domestic activity such as cooking can lead to exposures as high as those of occupational exposure activities. Implications: The approach of this study considers the determination of alveolar deposited surface area of aerosols generated from cooking activities, namely, typical Portuguese dishes. This type of measurement has not been done so far, in spite of the recognition that cooking activity is a main source of submicrometer and ultrafine aerosols. The results have shown that the levels of generated aerosols surpass the outdoor concentrations in a major European town, which calls for further determinations, contributing to a better assessment of exposure of individuals to domestic activities such as this one. PMID:23155858

Bordado, J C; Gomes, J F; Albuquerque, P C

2012-10-01

41

Volatility and mixing states of ultrafine particles from biomass burning.  

PubMed

Fine and ultrafine carbonaceous aerosols produced from burning biomasses hold enormous importance in terms of assessing radiation balance and public health hazards. As such, volatility and mixing states of size-selected ultrafine particles (UFP) emitted from rice straw, oak, and pine burning were investigated by using volatility tandem differential mobility analyzer (VTDMA) technique in this study. Rice straw combustion produced unimodal size distributions of emitted aerosols, while bimodal size distributions from combustions of oak (hardwood) and pine (softwood) were obtained. A nearness of flue gas temperatures and a lower CO ratio of flaming combustion (FC) to smoldering combustion (SC) were characteristic differences found between softwood and hardwood. SC emitted larger mode particles in higher numbers than smaller mode particles, while the converse was true for FC. Rice straw open burning UFPs exhibited a volatilization behavior similar to that between FC and SC. In addition, internal mixing states were observed for size-selected UFPs in all biomasses for all combustion conditions, while external mixing states were only observed for rice straw combustion. Results for FC and open burning suggested there was an internal mixing of volatile organic carbon (OC) and non-volatile core (e.g., black carbon (BC)), while the SC in rice straw produced UFPs devoid of non-volatile core. Also, it was found that volatility of constituting OC in FC and SC particles was different. PMID:22244973

Maruf Hossain, A M M; Park, Seungho; Kim, Jae-Seok; Park, Kihong

2011-12-29

42

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...

43

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...

44

What Does Respirator Certification Tell Us About Filtration of Ultrafine Particles?  

Microsoft Academic Search

Recent interest in exposures to ultrafine particles (less than 100 nm) in both environmental and occupational settings led the authors to question whether the protocols used to certify respirator filters provide adequate attention to ultrafine aerosols. The authors reviewed the particle size distribution of challenge aerosols and evaluated the aerosol measurement method currently employed in the National Institute for Occupational

Robert M. Eninger; Takeshi Honda; Tiina Reponen; Roy McKay; Sergey A. Grinshpun

2008-01-01

45

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

46

Exposure to Inhalable, Respirable, and Ultrafine Particles in Welding Fume  

PubMed Central

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.

Pesch, Beate

2012-01-01

47

InterComparison of a Fast Mobility Particle Sizer and a Scanning Mobility Particle Sizer Incorporating an Ultrafine Water-Based Condensation Particle Counter  

Microsoft Academic Search

An Ultrafine Water-based Condensation Particle Counter (UWCPC), a Scanning Mobility Particle Sizer (SMPS) incorporating an UWCPC, and a Fast Mobility Particle Sizer (FMPS) were deployed to determine the number and size distribution of ultrafine particles. Comparisons of particle number concentrations measured by the UWCPC, SMPS, and FMPS were conducted to evaluate the performance of the two particle sizers using ambient

Cheol-Heon Jeong; Greg J. Evans

2009-01-01

48

Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles  

PubMed Central

Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) throughout their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nanomaterials. Information about safety and potential hazards is urgently needed. Results of older bio-kinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract. The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels. Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species. Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need for basic research on their interactions with subcellular structures. Additional considerations for assessing safety of engineered NSPs include careful selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and also the benefits of possible desirable effects. An interdisciplinary team approach (e.g., toxicology, materials science, medicine, molecular biology, and bioinformatics, to name a few) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment.

Oberdorster, Gunter; Oberdorster, Eva; Oberdorster, Jan

2005-01-01

49

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. ...

50

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

51

Ultrafine Particle Deposition and Clearance in the Healthy and Obstructed Lung  

Microsoft Academic Search

Numerous epidemiologic studies have shown associations between Increased plasma viscosity has been found in association with exposure to particulate air pollution and acute increases in morbid- elevated sulfur dioxide and particulate levels (7). A recent ity and mortality, particularly in persons with chronic obstructive study has also shown an association between ultrafine particu- pulmonary disease. The dosimetry of ultrafine particles

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

2002-01-01

52

The Los Angeles International Airport as a source of ultrafine particles and other pollutants to nearby communities  

Microsoft Academic Search

Air monitoring was performed in the vicinity of the Los Angeles International Airport (LAX) during the spring of 2003. The purpose of this monitoring was to determine the extent of airport emissions on downwind ambient air in a mixed use neighborhood that includes residences. A mobile air monitoring platform was developed and deployed to measure ultrafine particle numbers (UFP), size

Dane Westerdahl; Scott A. Fruin; Phillip L. Fine; Constantinos Sioutas

2008-01-01

53

Concentration response functions for ultrafine particles and all-cause mortality and hospital admissions: results of a European expert panel elicitation  

Microsoft Academic Search

Toxicological studies have provided evidence of the toxicity of ultrafine particles (UFP), but epidemiological evidence for health effects of ultrafines is limited. No quantitative summary currently exists of concentration-response functions for ultrafine particles that can be used in health impact assessment. The goal was to specify concentration-response functions for ultrafine particles in urban air including their uncertainty through an expert

Gerard Hoek; Hanna Boogaard; Anne Knol; Jeroen de Hartog; Pauline Slottje; Jon G. Ayres; Paul Borm; Bert Brunekreef; Ken Donaldson; Francesco Forastiere; Stephen Holgate; Wolfgang G. Kreyling; Benoit Nemery; Juha Pekkanen; Vicki Stone; H.-Erich Wichmann; Jeroen van der Sluijs

2010-01-01

54

An Ultrafine, Water-Based Condensation Particle Counter and its Evaluation under Field Conditions  

Microsoft Academic Search

An ultrafine, water-based condensation particle counter (U-WCPC, TSI Model 3786) has been compared to a butanol-based ultrafine counter (U-BCPC, TSI Model 3025) for measurement of atmospheric and freeway-tunnel aerosols. The U-WCPC utilizes a warm, wet-walled growth tube to activate and grow particles through water condensation in a laminar-flow. It has an aerosol sampling rate of 0.3 L\\/min, and a nominal

Kenjiro Iida; Mark R. Stolzenburg; Peter H. McMurry; James N. Smith; Frederick R. Quant; Derek R. Oberreit; Patricia B. Keady; Arantza Eiguren-Fernandez; Gregory S. Lewis; Nathan M. Kreisberg; Susanne V. Hering

2008-01-01

55

Ultrafine particle removal and generation by portable air cleaners  

NASA Astrophysics Data System (ADS)

Portable air cleaners can both remove and generate pollutants indoors. To investigate these phenomena, we conducted a two-phase investigation in a 14.75 m 3 stainless steel chamber. In the first phase, particle size-resolved (12.6-514 nm diameter) clean air delivery rates (CADR) and efficiencies were determined, as were ozone emission rates, for two high-efficiency particle arresting (HEPA) filters, one electrostatic precipitator with a fan, and two ion generators without fans. The two HEPA air cleaners had count average CADR (standard deviation) of 188 (30) and 324 (44) m 3 h -1; the electrostatic precipitator 284 (62) m 3 h -1; and the two ion generators 41 (11) and 35 (13) m 3 h -1. The electrostatic precipitator emitted ozone at a rate of 3.8±0.2 mg h -1, and the two ion generators 3.3±0.2 and 4.3±0.2 mg h -1. Ozone initiates reactions with certain unsaturated organic compounds that produce ultrafine and fine particles, carbonyls, other oxidized products, and free radicals. During the second phase, five different ion generators were operated separately in the presence of a plug-in liquid or solid air freshener, representing a strong terpene source. For air exchange rates of between 0.49 and 0.96 h -1, three ion generators acted as steady-state net particle generators in the entire measured range of 4.61-157 nm, and two generated particles in the range of approximately 10 to 39-55 nm. Terpene and aldehyde concentrations were also sampled for one ion generator, and concentrations of terpenes decreased and formaldehyde increased. Given these results, the pollutant removal benefits of ozone-generating air cleaners may be outweighed by the generation of indoor pollution.

Waring, Michael S.; Siegel, Jeffrey A.; Corsi, Richard L.

56

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

57

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

58

Biogenic iodine emissions and identification of end-products in coastal ultrafine particles during nucleation bursts  

Microsoft Academic Search

Ultrafine particles sampled during new particle formation bursts observed in the coastal zone were studied with transmission electron microscopy (TEM) and elemental analysis using energy-dispersive X ray (EDX). It was observed that both iodine and sulphur were present in the new particles with diameter below 10 mn. Gaseous emissions of halogen compounds from seaweeds were also measured at the same

J. M. Mäkelä; T. Hoffmann; C. Holzke; M. Väkevä; T. Suni; T. Mattila; P. P. Aalto; U. Tapper; E. I. Kauppinen; C. D. O'Dowd

2002-01-01

59

ULTRAFINE PARTICLE CONCENTRATIONS NEAR FREEWAYS AT NIGHT OR EARLY MORNING UNDER CALM WEATHER CONDITIONS  

EPA Science Inventory

There is evidence that ultrafine (UF) particles dominate the number concentrations in close proximity to the roadway. The UF particles are also known to be more toxic than larger sizes of PM on an equal mass basis. In this work, UF particle number concentrations were measured u...

60

Influence of sound wave characteristics on fluidization behaviors of ultrafine particles  

Microsoft Academic Search

The fluidization behaviors of ultrafine particles were investigated in an acoustic fluidized bed with one type of micron particles and two types of nanoparticles. With the assistance of sound wave having low sound frequency and high sound pressure level, the micron and nanoparticles can be fluidized smoothly with fluidization behaviors similar to those of Geldart Group A particles. It has

Qingjie Guo; Huie Liu; Wenzhong Shen; Xianghong Yan; Rugao Jia

2006-01-01

61

A new approach for on-line measurements of the chemistry of individual ultrafine particles  

NASA Astrophysics Data System (ADS)

Ultrafine aerosol particles, those with diameters less than 100nm, are abundant in the atmosphere and play a crucial role in climate through cloud formation and have a greater effect on human health than larger particles. The chemistry of ultrafine particles helps determine whether they will act as cloud condensation nuclei (CCN) as well as how they will affect human health. However, it is difficult to study the chemistry of ultrafine particles due to their low mass and small size for optical detection. Typically, long collection times are required to collect ultrafine particles onto substrates, leading to loss of temporal information and individual particle chemistry and source information. Single particle mass spectrometers that rely on optical detection of particles for subsequent chemical analysis cannot effectively analyze ultrafine particles. Growth of particles through condensation has been used in various sizing (i.e. condensation particle counter (CPC), cloud condensation nuclei counter (CCNc)), as well as chemical (i.e. particle into liquid system (PILS) and condensation growth and impaction system (C-GIS)) instruments. In order to study ultrafine particles, we couple a laminar flow, water condensation growth tube (GT) with an aerodynamic focusing lens aerosol time-of-flight mass spectrometer (ATOFMS). The GT used here is similar in principle to the water-based CPC. The particles are exposed to a region of high supersaturation where they grow in size by water vapor condensation. We have coupled this GT to a single particle mass spectrometry ATOFMS system. Using this combined approach, we are able to detect polystyrene latex spheres (PSLs) as small as 38nm compared to the lower size limit of 90 nm of the ATOFMS without the GT. A series of inorganic and organic chemical standards representative of ambient particles show that by evaporating the particles between the GT and ATOFMS, there is little change in the chemistry of the particles that have undergone this growth and evaporation process. We have successfully characterized ambient particles down to 50nm with this GT-ATOFMS system. This technique has great potential to expand our limited knowledge of the chemistry of ultrafine particles and their effect on both climate and human health.

Zauscher, M. D.; Lewis, G. S.; Hering, S. V.; Prather, K. A.

2009-12-01

62

PAHs, PAH-induced carcinogenic potency, and particle-extract-Induced cytotoxicity of traffic-related nano/ultrafine particles.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) bound in nano/ ultrafine particles from vehicle emissions may cause adverse health effects. However, little is known about the characteristics of the nanoparticle-bound PAHs and the PAH-associated carcinogenic potency/cytotoxicity; therefore, traffic-related nano/ultrafine particles were collected in this study using a microorifice uniform deposition impactor(MOUDI) and a nano-MOUDI. For PM0.056--18, the difference in size-distribution of particulate total-PAHs between non-after-rain and after-rain samples was statistically significant at alpha = 0.05; however, this difference was not significant for PM0.01--0.056. The PAH correlation between PM0.01--0.1 and PM0.1--1.8 was lower for the after-rain samples than forthe non-after-rain samples. The average particulate total-PAHs in five samplings displayed a trimodal distribution with a major peak in the Aitken mode (0.032--0.056 microm). About half of the particulate total-PAHs were in the ultrafine size range. The BaPeq sums of BaP, IND, and DBA (with toxic equivalence factors > or = 0.1) accounted for approximately 90% of the total-BaPeq in the nano/ultrafine particles, although these three compounds contributed little to the mass of the sampled particles. The mean content of the particle-bound total-PAHs/-BaPeqs and the PAH/BaPeq-derived carcinogenic potency followed the order nano > ultrafine > fine > coarse. For a sunny day sample, the cytotoxicity of particle extracts (using 1:1 (v/v) n-hexane/dichloromethane) was significantly higher (p < 0.05) for the nano (particularly the 10-18 nm)/ultrafine particles than for the coarser particles and bleomycin. Therefore, traffic-related nano and ultrafine particles are possibly cytotoxic. PMID:18589992

Lin, Chih-Chung; Chen, Shui-Jen; Huang, Kuo-Lin; Lee, Wen-Jhy; Lin, Wen-Yinn; Tsai, Jen-Hsiung; Chaung, Hso-Chi

2008-06-01

63

Numerical Simulation of Ultrafine Particle-Laden Cylinder Wake Flow with Coherent Structures  

NASA Astrophysics Data System (ADS)

The phenomena of the wake flows containing ultrafine particles such as dust and pollutant in the atmosphere are usually observed downwind of the mountains and buildings. Different from the usually heavy particles, the ultrafine particles suspended in fluid undergo the processes of nucleation, growth and coagulation. Coherent structure in typical occurrence of the stretching of the Karman vortex street can be clearly seen in above mentioned gas-particle wakes. The aim of the present study is to explore the effects of coherent structures on the coagulation and growth of ultrafine particles suspended in wake flow. The particle field is represented by employing a moment method to approximate the ultrafine particle general dynamic equation. The fluid flow is obtained by solving the continuity and momentum equations with the large eddy simulation method and the subgrid-scale stresses were parametrized using the dynamic eddy viscosity model. The calculated contours of vorticity were compared with the relevant experimental results. The instantaneous spatial-temporal distribution of the particles are given and analyzed. The effects of the coherent structure on the diffusion and distribution of particle number concentration, polydispersity are discussed in detail.

Wang, Changbin; Zhi, Shujie; Wan, Zhanhong; Sun, Zhilin; Ding, Hai

64

Personal exposure to ultrafine particles in the workplace: exploring sampling techniques and strategies.  

PubMed

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 consider exposures against surface area and number concentration. From earlier research it was hypothesized that results on number concentration and particle distributions may vary with distance to the source, limiting the reliability of estimates of personal exposure from results which were obtained using static measurement equipment. Therefore, a workplace study was conducted to explore the performance of measurement methods in a multi-source emission scenario as part of a sampling strategy to estimate personal exposure. In addition, a laboratory study was conducted to determine possible influences of both distance to source and time course on particle number concentration and particle size distribution. In both studies different measurement equipment and techniques were used to characterize (total) particle number concentration. These included a condensation particle counter (CPC), a scanning mobility particle sizer (SMPS) and an electrical low pressure impactor (ELPI). For the present studies CPC devices seemed to perform well for the identification of particle emission sources. The range of ultrafine particle number concentration can be detected by both SMPS and ELPI. An important advantage of the ELPI is that aerosols with ultrafine sizes can be collected for further analysis. Specific surface area of the aerosols can be estimated using gas adsorption analysis; however, with this technique ultrafine particles cannot be distinguished from particles with non-ultrafine sizes. Consequently, estimates based on samples collected from the breathing zone and scanning electron microscopic analysis may give a more reliable estimate of the specific surface area of the ultrafine particles responsible for personal exposure. The results of both the experimental and the workplace study suggest both spatial and temporal variation in total number concentration and aerosol size distribution. Therefore, the results obtained from static measurements and grab sampling should be interpreted with care as estimates of personal exposure. For evaluation of workplace exposure to ultrafine particles it is recommended that all relevant characteristics of such exposure are measured as part of a well-designed sampling strategy. PMID:15240340

Brouwer, Derk H; Gijsbers, José H J; Lurvink, Marc W M

2004-07-07

65

Chemical preparation and characterization of metal–metalloid ultrafine amorphous alloy particles  

Microsoft Academic Search

Ultrafine amorphous alloy particles (UAAP) constitute an overlapping area of amorphous alloys and nanophase materials. Special properties of the particles derived from the combination of their long-range disordered structure and nanoscale size are of great interest in catalysis. This paper reviews some fundamental aspects in the chemical preparation of UAAP consisting of transition metal (M) and metalloid elements (B, P)

Yi Chen

1998-01-01

66

Ultrafine particles from diesel engines induce vascular oxidative stress via JNK activation  

Microsoft Academic Search

Exposure to particulate air pollution is linked to increased incidences of cardiovascular diseases. Ambient ultrafine particles (UFP) from diesel vehicle engines have been shown to be proatherogenic in ApoE knockout mice and may constitute a major cardiovascular risk in humans. We posited that circulating nano-sized particles from traffic pollution sources induce vascular oxidative stress via JNK activation in endothelial cells.

Rongsong Li; Zhi Ning; Jeffery Cui; Bhavraj Khalsa; Lisong Ai; Wakako Takabe; Tyler Beebe; Rohit Majumdar; Constantinos Sioutas; Tzung Hsiai

2009-01-01

67

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

68

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

69

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...

70

TRANSLOCATION OF ULTRAFINE INSOLUBLE IRIDIUM PARTICLES FROM LUNG EPITHELIUM TO EXTRAPULMONARY ORGANS IS SIZE DEPENDENT BUT VERY LOW  

Microsoft Academic Search

Recently it was speculated that ultrafine particles may translocate from deposition sites in the lungs to systemic circulation. This could lead to accumulation and potentially adverse reactions in critical organs such as liver, heart, and even brain, consistent with the hypothesis that ultrafine insoluble particles may play a role in the onset of cardiovascular diseases, as growing evidence from epidemiological

W. G. Kreyling; M. Semmler; F. Erbe; P. Mayer; S. Takenaka; H. Schulz; G. Oberdörster; A. Ziesenis

2002-01-01

71

Human pulmonary responses to experimental inhalation of high concentration fine and ultrafine magnesium oxide particles.  

PubMed Central

Exposure to air polluted with particles less than 2.5 micron in size is associated epidemiologically with adverse cardiopulmonary health consequences in humans. The goal of this study was to characterize human pulmonary responses to controlled experimental high-dose exposure to fine and ultrafine magnesium oxide particles. We quantified bronchoalveolar lavage (BAL) cell and cytokine concentrations, pulmonary function, and peripheral blood neutrophil concentrations in six healthy volunteers 18 to 20 hr after inhalation of fine and ultrafine magnesium oxide particles produced from a furnace system model. We compared postexposure studies with control studies from the same six subjects. Mean +/- standard deviation (SD) cumulative magnesium dose was 4,138 +/- 2,163 min x mg/m3. By weight, 28% of fume particles were ultrafine (<0.1 micron in diameter) and over 98% of fume particles were fine (<2.5 micron in diameter). There were no significant differences in BAL inflammatory cell concentrations, BAL interleukin (IL)-1, IL-6, IL-8, tumor necrosis factor, pulmonary function, or peripheral blood neutrophil concentrations postexposure compared with control. Our findings suggest that high-dose fine and ultrafine magnesium oxide particle exposure does not produce a measurable pulmonary inflammatory response. These findings are in marked contrast with the well-described pulmonary inflammatory response following zinc oxide particle inhalation. We conclude that fine and ultrafine particle inhalation does not result in toxicity in a generic manner independent of particle composition. Our findings support the concept that particle chemical composition, in addition to particle size, is an important determinant of respiratory effects. Images Figure 1. Figure 2. A Figure 2. B

Kuschner, W G; Wong, H; D'Alessandro, A; Quinlan, P; Blanc, P D

1997-01-01

72

Preparation of ultrafine metal particles\\/polyurethane composites  

Microsoft Academic Search

A new type of coordination polyurethane was prepared by incorporating the transition metal ions into the pyridine containing thermoplastic polyurethane films. Then the metal ions dispersed in the polyurethane matrix were reduced by controlling the exposure of the metal sites to NaBH4 under mild condition. The reduction of the polyurethane metal complex films resulted in the production of amorphous ultrafine

Lei Chen; Kang Liu; Chang-zheng Yang

1996-01-01

73

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

74

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

75

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

76

[Research on NEDC ultrafine particle emission characters of a port fuel injection gasoline car].  

PubMed

A Santana gasoline car with multi-port fuel injection (PFI) system was used as the research prototype and an engine exhaust particle sizer (EEPS) was employed to investigate the exhaust ultrafine particle number and size distribution characters of the tested vehicle in new European driving cycle (NEDC). The tested results showed that the vehicle's nuclear particle number, accumulation particle number, as well as the total particle number emission increased when the car drove in accelerated passage, and the vehicle's particle number emission was high during the first 40 seconds after test started and when the speed was over 90 km x h(-1) in extra urban driving cycle (EUDC) in NEDC. The ultrafine particle distribution of the whole NEDC showed a single peak logarithmic distribution, with diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameter was 24 nm. The ultrafine particle distribution of the urban driving cycle named by the economic commission for Europe (ECE) e. g. ECE I, ECE II - IV, the extra urban driving cycle e. g. EUDC, and the idling, constant speed, acceleration, deceleration operation conditions of NEDC all showed a single peak logarithmic distribution, also with particle diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameters of different driving cycle and different driving mode were from 14 nm to 42 nm. Therefore, the ultrafine particle emissions of the tested PFI gasoline car were mainly consisted of nuclear mode particles with a diameter of less than 50 nm. PMID:23379140

Hu, Zhi-Yuan; Li, Jin; Tan, Pi-Qiang; Lou, Di-Ming

2012-12-01

77

Water-based condensation particle counters for environmental monitoring of ultrafine particles.  

PubMed

TSI Inc. (Shoreview, MN) has introduced three new water-based condensation particle counters (WCPCS) that were designed to detect airborne particles larger than 2.5 nm (model 3786), 5 nm (model 3785), and either 10 or 20 nm (model 3782). These WCPCs are well suited for real-time, environmental monitoring of number concentration of airborne ultrafine particles. Their unique design incorporates the use of water as the working fluid instead of alcohol. Water is odor free, readily available, and eliminates the problem of water condensation and absorption into alcohol working fluids during operation in humid environments. In this study, the performance of three TSI WCPCs was characterized for several aerosol compositions, including sucrose, salt (NaCl), dioctyl sebacate (DOS), dioctyl phthalate (DOP), emery oil (poly-alpha-olefin), silver, impurity residue particles, and ambient aerosol particles. All particles were size selected using a nano differential mobility analyzer (nano-DMA; model 3085, TSI Inc.) to create monodisperse challenge aerosols. The challenge aerosol was mixed uniformly with clean makeup flow and split into a WCPC and a reference instrument to determine the counting efficiency of the WCPC. For the model 3785 WCPC, the D50 (i.e., the particle diameter with 50% counting efficiency) was determined to be 3.1 nm for salt particles, 4.7 nm for sucrose and ambient particles, 5.6 nm for silver particles, and >50 nm for ultrapure oil particles. The sensitivity to oil droplets increased dramatically (D50 < 10 nm) when the oil was slightly contaminated. The D50 of model 3786 ultrafine water-based CPC (UWCPC) was 2.4 nm for impurity residue particles. The D50 of the model 3782 WCPC was 10.8 (with a nominal setting of 10 nm) or 19.8 nm (with a nominal setting of 20 nm) for sucrose particles. All three WCPCs have response times of less than 2 or 3 sec and are therefore able to detect fast-changing events. PMID:16681209

Liu, Wei; Kaufman, Stanley L; Osmondson, Brian L; Sem, Gilmore J; Quant, Frederick R; Oberreit, Derek R

2006-04-01

78

Characterization of the University of Toronto Concentrated Aerosol Particle Exposure Facility (CAPEF)—Effects on fine and ultrafine non-refractory aerosol composition  

Microsoft Academic Search

Virtual impactor-based particle concentrators have been developed to enable the study of biological mechanisms and dose-response relationships of PM inhalation. The Concentrated Aerosol Particle Exposure Facility (CAPEF) at University of Toronto houses Harvard School of Public Health-designed coarse, fine, and quasi-ultrafine particle concentrators for such studies. Characterization of the concentration of the non-refractory components of ambient particles was carried out

Robert D. McWhinney; Neeraj Rastogi; Bruce Urch; Frances Silverman; Jeffrey R. Brook; Greg J. Evans; Jonathan P. D. Abbatt

2012-01-01

79

Exposure to ultrafine and fine particles and noise during cycling and driving in 11 Dutch cities  

Microsoft Academic Search

Recent studies have suggested that exposures during traffic participation may be associated with adverse health effects. Traffic participation involves relatively short but high exposures. Potentially relevant exposures include ultrafine particles, fine particles (PM2.5) and noise.Simultaneously, detailed real time exposure of particle number concentration (PNC), PM2.5 and noise has been measured while driving and cycling 12 predefined routes of approximately 10–20 min

Hanna Boogaard; Frank Borgman; Jaap Kamminga; Gerard Hoek

2009-01-01

80

A novel wet chemistry\\/two-step calcining process for the synthesis of ultrafine ?-Al 2O 3 particles  

Microsoft Academic Search

Ultrafine ?-Al2O3 particles have been synthesized via a wet chemistry\\/two-step calcining process. X-ray diffraction (XRD) analysis shows that the as-synthesized particles are of single-phase ?-Al2O3. The grain size of the particles is examined by TEM analysis and is found to be around 80–100 nm. The study demonstrates a novel process for the synthesis of ultrafine ?-Al2O3 particles.

Jie-Hua Wu; Bao-Shun Li; Jing-Kun Guo

2001-01-01

81

Ultrafine Particle Emissions and Exposure Measurement in South Australian Workplaces - A Pilot Study  

Microsoft Academic Search

Airborne ultrafine particles (UFPs) are encountered in many working environments and have been associated with a range of potential health risks, including cardio-respiratory disease. However, there are no generic occupational exposure standards for ambient UFPs (less than < 100 nm in diameter) and generally there is a shortage of relevant exposure data. The aim of this pilot study was to

S Lee; X Liu; A Deemer; B Sanderson; D. Pisaniello

82

Removal of ultrafine particles in indoor air: Performance of various portable air cleaner technologies  

Microsoft Academic Search

Ultrafine particle (UFP) exposures have been associated with human morbidity and mortality. The removal of UFP from indoor air using portable air cleaners (PACs) of various technologies has not been studied in detail. In this study, 12 devices representing different PAC technologies were tested with an UFP challenge in a full-scale stainless-steel chamber. UFP generation and measurements were conducted using

Zuraimi M. Sultan; Gregory J. Nilsson; Robert J. Magee

2011-01-01

83

Effect of interparticle forces on the coagulation of ultrafine SiO 2 particles  

Microsoft Academic Search

The mechanism of ultrafine (2 particle production under thermal arc plasma conditions is studied by modelling. Two cases of the process are considered in the model: (i) when it is determined as a pure free-molecular coagulation; (ii) when the coagulation is influenced by the interparticle forces. The Hamaker formula is used to present the van der Waals forces between the

E. Balabanova; D. Oliver

1996-01-01

84

Ultrafine Particles Affect Experimental Thrombosis in an In Vivo Hamster Model  

Microsoft Academic Search

Particulate air pollution is associated with cardiovascular morbidity systems, such as coagulation. The rationale of these studies and mortality. To investigate this association, we studied the effect is that cytokines and other mediators produced in the lungs of ultrafine (60 nm) polystyrene particles on thrombus formation are also released in the circulation and exert extrapulmonary in a hamster model after

Abderrahim Nemmar; Marc F. Hoylaerts; Peter H. M. Hoet; David Dinsdale; Tim Smith; Haiyan Xu; Jozef Vermylen; Benoit Nemery

85

Translocation of Inhaled Ultrafine Manganese Oxide Particles to the Central Nervous System  

Microsoft Academic Search

BACKGROUND: Studies in monkeys with intranasally instilled gold ultrafine particles (UFPs; < 100 nm) and in rats with inhaled carbon UFPs suggested that solid UFPs deposited in the nose travel along the olfactory nerve to the olfactory bulb. METHODS: To determine if olfactory translocation occurs for other solid metal UFPs and assess potential health effects, we exposed groups of rats

Alison Elder; Robert Gelein; Vanessa Silva; Tessa Feikert; Lisa Opanashuk; Janet Carter; Russell Potter; Andrew Maynard; Yasuo Ito; Jacob Finkelstein; Günter Oberdörster

2006-01-01

86

Observations of ultrafine aerosol particle formation and growth in boreal forest  

Microsoft Academic Search

Number size distribution of ambient submicron and ultrafine aerosol particles have been measured on a continuous basis (every 10 minutes) for three quarters of the year 1996, at a forest site in Southern Finland. Continuous monitoring offers additional insight over the diurnal dynamics of the submicron size distribution, including existence of clearly separate size modes as well as events of

J. M. Mäkelä; P. Aalto; V. Jokinen; T. Pohja; A. Nissinen; S. Palmroth; T. Markkanen; K. Seitsonen; H. Lihavainen; M. Kulmala

1997-01-01

87

Expert elicitation on ultrafine particles: likelihood of health effects and causal pathways  

Microsoft Academic Search

BACKGROUND: Exposure to fine ambient particulate matter (PM) has consistently been associated with increased morbidity and mortality. The relationship between exposure to ultrafine particles (UFP) and health effects is less firmly established. If UFP cause health effects independently from coarser fractions, this could affect health impact assessment of air pollution, which would possibly lead to alternative policy options to be

Anne Barbara Knol; Jeroen J de Hartog; Hanna Boogaard; Pauline Slottje; Jeroen P van der Sluijs; Erik Lebret; Flemming R. Cassee; J Arjan Wardekker; Jon G Ayres; Paul J. Borm; Bert Brunekreef; Kenneth Donaldson; Francesco Forastiere; Stephen T Holgate; Wolfgang G. Kreyling; Benoit Nemery; Juha Pekkanen; Vicky Stone; H-Erich Wichmann; Gerard Hoek

2009-01-01

88

Indoor air quality for chemical and ultrafine particle contaminants from printers  

Microsoft Academic Search

There are various emission sources of chemical contaminants, such as volatile organic compounds (VOCs) and ozone and particulate matter. This report is a study into the indoor air of a room containing either a laser printer\\/ink-jet printer, and the air contaminations were monitored for VOCs, ozone and ultrafine particle. The result confirmed an increase in the concentration of ozone and

Naoki Kagi; Shuji Fujii; Youhei Horiba; Norikazu Namiki; Yoshio Ohtani; Hitoshi Emi; Hajime Tamura; Yong Shik Kim

2007-01-01

89

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

SciTech Connect

The morphological and chemical nature of ultrafine iron catalyst particles (3-5 nm diameters) during activation/FTS was studied by HRTEM, EELS, and Moessbauer spectroscopy. With the progress of FTS, the carbide re-oxidized to magnetite and catalyst activity gradually decreased. The growth of oxide phase continued and average particle size also increased simultaneously. The phase transformation occurred in a ''growing oxide core'' manner with different nano-zones. The nano-range carbide particles did not show fragmentation or attrition as generally observed in micrometer range particles. Nevertheless, when the dimension of particles reached the micrometer range, the crystalline carbide phase appeared to be sprouted on the surface of magnetite single crystal. In the previous reporting period, a 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. During the current reporting period, we have started construction of the new filtration system and began modifications to the 4 liter slurry bubble column reactor (SBCR) reactor. The system will utilize a primary wax separation device followed by a Pall Accusep or Membralox ceramic cross-flow membrane. As of this writing, the unit is nearly complete except for the modification of a moyno-type pump; the pump was shipped to the manufacturer to install a special leak-free, high pressure seal.

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

2006-03-31

90

Multimodal ultrafine particles from pulverized coal combustion in a laboratory scale reactor  

SciTech Connect

Particle size distribution functions have been measured in a ethanol fueled flame reactor fed with a low amount of pulverized coal particles. The reactor is operated in low (5.0 vol.%) and high (76.5 vol.%) oxygen concentrations using two high volatile bituminous Colombian and Indonesian coals. A carbon black powder is also oxidized in the same conditions. Generated particles are sampled using rapid-dilution probes and the size distribution functions are measured on-line by a high resolution Differential Mobility Analyzer. Results clearly show that ultrafine particles, those with sizes lower than 100 nm, have a multimodal size distribution function. These particles have huge number concentrations in both investigated conditions whereas their formation is enhanced in the oxygen enriched condition. Ultrafine particles are almost totally dominated in number by the fraction having sizes below 30 nm. Nanoparticles also account for a significant fraction of total particle mass and slowly coagulate in the reactor. The shape of the size distribution functions is not affected by the coal type, at least for the two investigated coals. Results suggest that ultrafine particles form through the vaporization-nucleation-growth pathway involving inorganic ashes. Moreover the contribution of carbonaceous particles seems particularly important for size smaller than 5 nm. (author)

Carbone, Francesco; Beretta, Federico [Istituto di Ricerche sulla Combustione, Consiglio Nazionale delle Ricerche, piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); D'Anna, Andrea [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli Federico II, piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy)

2010-07-15

91

Ultrafine pitch Pb-free & eutectic solder bumping with fine particle size solder paste for nano packaging  

Microsoft Academic Search

With the demand for electronic component miniaturization with high functionality, high density assemblies requires finer interconnect features and pitches, which cannot be met using conventional solder paste screen printing. Ultra-fine pitch solder deposition can be carried out by electroplating but with related cost and environmental issues. This paper discusses a feasible deposition process for ultra-fine pitch using fine particle size

Vaidyanathan Kripesh; Wong Wai Kwan; Mahadeven Iyer

2003-01-01

92

Spatial Measurements of Ultrafine Particles Using an Engine Exhaust Particle Sizer within a Local Community Downwind of a Major International Trade Bridge in Buffalo, New York  

Microsoft Academic Search

Ultrafine particles (UFP) can be defined as having at least one dimension that is less than 100 nanometers. Because of their dimensions, they exhibit unique properties that affect atmospheric transport, exposures, and possibly health endpoints. Freshly generated Diesel particulate matter (DPM) is predominantly in the ultrafine particle size range size range, which in practice is defined by the detection characteristics

Timothy R. McAuley; Andrea Ferro; John D. Spengler; Philip K. Hopke; Peter A. Jaques

2010-01-01

93

Ultrafine particle emission from incinerators: the role of the fabric filter.  

PubMed

Incinerators are claimed to be responsible of particle and gaseous emissions: to this purpose Best Available Techniques (BAT) are used in the flue-gas treatment sections leading to pollutant emission lower than established threshold limit values. As regard particle emission, only a mass-based threshold limit is required by the regulatory authorities. However; in the last years the attention of medical experts moved from coarse and fine particles towards ultrafine particles (UFPs; diameter less than 0.1 microm), mainly emitted by combustion processes. According to toxicological and epidemiological studies, 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. A further topic to be stressed in the UFP emission from incinerators is the particle filtration efficiency as function of different flue-gas treatment sections. In fact, it could be somehow important to know which particle filtration method is able to assure high abatement efficiency also in terms of UFPs. To this purpose, in the present work experimental results in terms of ultrafine particle emissions from several incineration plants are reported. Experimental campaigns were carried out in the period 2007-2010 by measuring UFP number distributions and total concentrations at the stack of five plants through condensation particle counters and mobility particle sizer spectrometers. Average total particle number concentrations ranging from 0.4 x 10(3) to 6.0 x 10(3) particles cm(-3) were measured at the stack of the analyzed plants. Further experimental campaigns were performed to characterize particle levels before the fabric filters in two of the analyzed plants in order to deepen their particle reduction effect; particle concentrations higher than 1 x 10(7) particles cm(-3) were measured, leading to filtration efficiency greater than 99.99%. PMID:22393815

Buonanno, G; Scungio, M; Stabile, L; Tirler, W

2012-01-01

94

Comparing Inhaled Ultrafine versus Fine Zinc Oxide Particles in Healthy Adults  

PubMed Central

Rationale: Zinc oxide is a common, biologically active constituent of particulate air pollution as well as a workplace toxin. Ultrafine particles (< 0.1 ?m diameter) are believed to be more potent than an equal mass of inhaled accumulation mode particles (0.1–1.0 ?m diameter). Objectives: We compared exposure–response relationships for respiratory, hematologic, and cardiovascular endpoints between ultrafine and accumulation mode zinc oxide particles. Methods: In a human inhalation study, 12 healthy adults inhaled 500 ?g/m3 of ultrafine zinc oxide, the same mass of fine zinc oxide, and filtered air while at rest for 2 hours. Measurements and Main Results: Preexposure and follow-up studies of symptoms, leukocyte surface markers, hemostasis, and cardiac electrophysiology were conducted to 24 hours post-exposure. Induced sputum was sampled 24 hours after exposure. No differences were detected between any of the three exposure conditions at this level of exposure. Conclusions: Freshly generated zinc oxide in the fine or ultrafine fractions inhaled by healthy subjects at rest at a concentration of 500 ?g/m3 for 2 hours is below the threshold for acute systemic effects as detected by these endpoints.

Beckett, William S.; Chalupa, David F.; Pauly-Brown, Andrea; Speers, Donna M.; Stewart, Judith C.; Frampton, Mark W.; Utell, Mark J.; Huang, Li-Shan; Cox, Christopher; Zareba, Wojciech; Oberdorster, Gunter

2005-01-01

95

Study on preparation of ultrafine amorphous particles by chemical reduction  

NASA Astrophysics Data System (ADS)

Ultrafine amorphous FeNiB powder was prepared by potassium borohydride reduction by mixing the aqueous solutions in a bath of supersonic oscillator. Different mixing ratios of potassium borohydride to metal salt were applied. Analysis of the composition of the sample and the Fe2+ and Ni2+ remaining in the filtrate after preparation shows that a quantity of KBH4 about 1.5 times the stoichiometrical quantity is enough. Mössbauer measurements were performed at room temperature and it was found that excess KBH4 makes no distinct difference in the spectra of the samples.

Song, Xu; Yusheng, Xu; Huali, Jiang; Qing, Xue

1993-04-01

96

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

97

A system for aerodynamically sizing ultrafine environmental radioactive particles  

SciTech Connect

The unattached environmental radioactive particles/clusters, produced mainly by {sup 222}Rn in indoor air, are usually few nanometers in size. The inhalation of these radioactive clusters can lead to deposition of radioactivity on the mucosal surface of the tracheobronchial tree. The ultimate size of the cluster together with the flow characteristics will determine the depositional site in the human lung and thus, the extent of damage that can be caused. Thus, there exists the need for the determination of the size of the radioactive clusters. However, the existing particle measuring device have low resolution in the sub-nanometer range. In this research, a system for the alternative detection and measurement of the size of particles/cluster in the less than 2 nm range have been developed. The system is a one stage impactor which has a solid state spectrometer as its impaction plate. It`s major feature is the nozzle-to-plate separation, L. The particle size collected changes with L and thus, particle size spectroscopy is achieved by varying L. The number of collected particles is determined by alpha spectroscopy. The size-discriminating ability of the system was tested with laboratory generated radon particles and it was subsequently used to characterize the physical (size) changes associated with the interaction of radon progeny with water vapor and short chain alcohols in various support gases. The theory of both traditional and high velocity jet impactors together with the design and evaluation of the system developed in this study are discussed in various chapters of this dissertation. The major results obtained in the course of the study are also presented.

Olawoyin, L.

1995-09-01

98

Characterization of ultrafine coal fly ash particles by energy-filtered TEM  

Microsoft Academic Search

Summary In this study, energy-filtered transmission electron microscopy is demonstrated to be a valuable tool for characterizing ultrafine coal fly ash particles, especially those particles encapsulated in or associated with carbon. By examining a series of elemental maps (K-edge maps of C and O, and L-edge maps of Si, Al, Ti and Fe) recorded using the three-window method, consider- able

Y. CHEN; N. SHAH; F. E. HUGGINS; G. P. HUFFMAN; A. DOZIER

2005-01-01

99

Energy Absorption at Particle Contact, Compression, and Shear Flow of Dry Ultrafine Powder  

Microsoft Academic Search

The mechanical behavior of dry, ultrafine cohesive powders (particle size d < 10 ?m) is characterized by insufficient flowability and large compressibility. Consequently, a comparatively large energy input is necessary to promote the non-rapid frictional shear flow in powder handling practice. A micro-mechanical approach is briefly explained first. When two adhesive particles come in contact, the constitutive models of four characteristic stressing modes,

J. Tomas

2009-01-01

100

Instillation of Six Different Ultrafine Carbon Particles Indicates a Surface Area Threshold Dose for Acute Lung Inflammation in Mice  

PubMed Central

Increased levels of particulate air pollution are associated with increased respiratory and cardiovascular mortality and morbidity. Some epidemiologic and toxicologic research suggests ultrafine particles (UFPs) (< 100 nm) to be more harmful per unit mass than larger particles. Our study was aimed at a quantitative comparison of acute adverse effects of different types of carbonaceous UFPs at a dose range that causes a moderate inflammatory response in lungs. We used six different particle types (primary particle size 10–50 nm, specific surface area 30–800 m2/g, and organic content 1–20%): PrintexG, Printex90, flame soot particles with different organic content (SootL, SootH), spark-generated ultrafine carbon particles (ufCP), and the reference diesel exhaust particles (DEP) SRM1650a. Mice were instilled with 5, 20, and 50 ?g of each particle type, and bronchoalveolar lavage was analyzed 24 hr after instillation for inflammatory cells and the level of proinflammatory cytokines. At respective mass-doses, particle-caused detrimental effects ranked in the following order: ufCP > SootL ? SootH > Printex90 > PrintexG > DEP. Relating the inflammatory effects to the particle characteristics—organic content, primary particle size, or specific surface area—demonstrates the most obvious dose response for particle surface area. Our study suggests that the surface area measurement developed by Brunauer, Emmett, and Teller is a valuable reference unit for the assessment of causative health effects for carbonaceous UFPs. Additionally, we demonstrated the existence of a threshold for the particle surface area at an instilled dose of approximately 20 cm2, below which no acute proinflammatory responses could be detected in mice.

Stoeger, Tobias; Reinhard, Claudia; Takenaka, Shinji; Schroeppel, Andreas; Karg, Erwin; Ritter, Baerbel; Heyder, Joachim; Schulz, Holger

2006-01-01

101

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...

102

Aircraft measurements of vertical ultrafine particles profiles over Northern China coastal areas during dust storms in 2006  

Microsoft Academic Search

The vertical distribution of ultrafine particles over Northern China coastal areas was measured by aircraft equipped with a high space–time resolution instrument during dust storms in spring of 2006. Three different types of conditions were observed, i.e. dust storm, weak dust storm and non-dust storm. Results indicate that the number concentration of ultrafine particles can reach up to 1.2×105cm?3 during

Wei Wang; Jianzhong Ma; Shiro Hatakeyama; Xiaoyu Liu; Yue Chen; Akinori Takami; Lihong Ren; Chunmei Geng

2008-01-01

103

The measurement of ultrafine particles: A pilot study using a portable particle counting technique to measure generated particles during a micromachining process  

Microsoft Academic Search

The accurate measurement of airborne particles in the nanometer range is a challenging task. Because several studies have linked exposures to airborne ultrafine particles to elevated human health risks, the need to assess the concentrations of particles in the workplace that are below 100 nm in diameter is imperative. Several different techniques for monitoring nanoparticles are now available, and others

Rodney G. Handy; Mark J. Jackson; Grant M. Robinson; Michael D. Lafreniere

2006-01-01

104

Effects of ultrafine particles-induced oxidative stress on Clara cells in allergic lung inflammation  

Microsoft Academic Search

BACKGROUND: Clara cell protein (CC16), the main secretory product of bronchiolar Clara cells, plays an important protective role in the respiratory tract against oxidative stress and inflammation. The purpose of the study was to investigate the role of elemental carbon ultrafine particles (EC-UFP)-induced oxidative stress on Clara cells and CC16 in a mouse model of allergic lung inflammation. METHODS: Ovalbumin

Francesca Alessandrini; Ingrid Weichenmeier; Erik van Miert; Shinji Takenaka; Erwin Karg; Cornelia Blume; Martin Mempel; Holger Schulz; Alfred Bernard; Heidrun Behrendt

2010-01-01

105

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

106

Glass crystallization synthesis of ultrafine hexagonal M-type ferrites: Particle morphology and magnetic characteristics  

Microsoft Academic Search

This review concerns the synthesis and functional properties of ultrafine particles of M-type hexagonal ferrites prepared\\u000a by the most advanced process of oxide glass crystallization. Hexaferrite phase formation during the heat treatment of multicomponent\\u000a oxide glasses of various chemical compositions containing boron and\\/or silicon oxides as glass formers is considered. This\\u000a route is useful to prepare assemblies of single-crystal strontium

P. E. Kazin; L. A. Trusov; D. D. Zaitsev; Yu. D. Tret’yakov

2009-01-01

107

Relationship between molecular states (conformation and orientation) and activities of ?-amylase adsorbed on ultrafine silica particles  

Microsoft Academic Search

Bacillus subtilis ?-amylase, which contains a relatively large amount of ?-helix, was adsorbed on two types of ultrafine silica particles (silica-1\\u000a and-2, average diameter 15 nm) under various conditions. The changes in circular dichroism (CD) spectra of ?-amylase upon\\u000a adsorption were measured, and the extent of conformational changes was estimated from the reduction in ?-helix content. In\\u000a additions the activities

A. Kondo; T. Urabe

1995-01-01

108

Relationships between molecular states (conformation and orientation) and activities of ?-amylase adsorbed on ultrafine silica particles  

Microsoft Academic Search

Bacillus subtilis?-amylase, which contains a relatively large amount of ?-helix, was adsorbed on two types of ultrafine silica particles (silica-1\\u000a and -2, average diameter 15?nm) under various conditions. The changes in circular dichroism (CD) spectra of ?-amylase upon\\u000a adsorption were measured, and the extent of conformational changes was estimated from the reduction in ?-helix content. In\\u000a addition, the activities of

A. Kondo; T. Urabe

1995-01-01

109

An Ultrafine Aerosol Condensation Nucleus Counter  

Microsoft Academic Search

The development of a condensation nucleus counter (CNC) for detecting ultrafine aerosol (UFA) particles (particle diameter ?20 nm) is described here. This instrument is designed specifically for high-efficiency detection and counting of ultrafine particles. It is a modified version of the TSI model 3020 continuous flow, single-particle-counting condensation nucleus counter with sequential saturator and condenser. Design modifications incorporating aerosol sheathing

Mark R. Stolzenburg; Peter H. McMurry

1991-01-01

110

An innovative antisolvent precipitation process as a promising technique to prepare ultrafine rifampicin particles  

NASA Astrophysics Data System (ADS)

Many existing and new drugs fail to be fully utilized because of their limited bioavailability due to poor solubility in aqueous media (BCS drug classes II and IV). In this work, for accelerating dissolution of this kind of poorly water-soluble drugs, an antisolvent precipitation method that does not require the use of conventional volatile organic solvents is proposed. To demonstrate this technique, ultrafine particles of rifampicin were prepared using a room temperature ionic liquid (1-ethyl 3- methyl imidazolium methyl-phosphonate) as an alternative solvent and a phosphate buffer as an antisolvent.Rifampicin solubility was measured in various solvents (1-ethyl 3-methyl imidazolium methylphosphonate, water and phosphate buffer), showing the RTIL good solvency for the model drug: rifampicin solubility was found to be higher than 90 mg/g in RTIL at 30 °C and lower than 1 mg/g in water at 25 °C. Additionally, it was demonstrated that introduction of rifampicin solution in 1-ethyl 3- methyl imidazolium methyl-phosphonate into the aqueous solution antisolvent can produce particles in the submicron range with or without hydroxypropyl methylcellulose as the stabilizer. The ultrafine particles (280-360 nm) are amorphous with enhanced solubility and faster dissolution rate. To our knowledge, this is the first published work examining the suitability of using RTILs for ultrafine drug nanoparticles preparation by an antisolvent precipitation process.

Viçosa, Alessandra; Letourneau, Jean-Jacques; Espitalier, Fabienne; Inês Ré, Maria

2012-03-01

111

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

112

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

113

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

114

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

115

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

116

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

117

Observations of ultrafine particle nucleation events in the tropical UT\\/LS over West Africa and Brazil  

Microsoft Academic Search

New particle formation by gas to particle conversion in the tropical upper troposphere and lower stratosphere (UT\\/LS) may be a major source of aerosols for origin and maintenance of the global stratospheric Junge aerosol layer. Once created in the tropical upper troposphere these ultrafine particles can be carried aloft towards the tropopause by the -radiatively driven- slowly rising air, and

S. Borrmann; J. Curtius; D. Kunkel; R. Weigel; S. Vicani; C. Schiller; A. Ulanovski; F. Ravegnani; K. A. Law

2009-01-01

118

Axial flow cyclone for segregation and collection of ultrafine particles: theoretical and experimental study.  

PubMed

In this study, an axial flow cyclone was designed, fabricated, and evaluated at different conditions of air flow rates (Q0) and low-pressure environments (P), especially for the segregation and collection of ultrafine particles. An evaporation/condensation type of aerosol generation system consisting of tube furnace and mixing chamber was employed to produce test aerosols. The test aerosol was then classified by a differential mobility analyzer (DMA) and number concentration was measured by a condensation nuclei counter (CNC) and an electrometer upstream and downstream of the cyclone, respectively. The s-shaped curve of the collection efficiency in submicron particle size range was obtained to be similar to the traditional cyclone found in the literatures when the particles were largerthan 40 nm at Q0 = 1.07, 0.455 L(STP)/min, and P = 4.8-500 Torr. The curve was found to be fitted very well by a semiempirical equation described in this paper. For particles smaller than 40 nm, however, the collection efficiency was unusually increased as the particle diameter was decreased due to the fact that the diffusion deposition becomes the dominant collection mechanism in the low-pressure conditions. A model composed of centrifugal force and diffusion deposition is presented and used to fit the experimental data. The cyclone was demonstrated to separate and collect ultrafine particles effectively in the tested vacuum conditions. PMID:15787370

Hsu, Yu-Du; Chein, Hung Min; Chen, Tzu Ming; Tsai, Chuen-Jinn

2005-03-01

119

Investigation on the potential generation of ultrafine particles from the tire-road interface  

NASA Astrophysics Data System (ADS)

There has been some discussion in the literature on the generation of ultrafine particles from tire abrasion of studded and non-studded tires tested in the laboratory environment.In the present study, the potential generation of ultrafine particles from the tire road interface was investigated during real driving. An instrumented Sport Utility Vehicle equipped with summer tires was used to measure particle concentrations with high temporal resolution inside the wheel housing while driving on a regular asphalt road. Different driving conditions, i.e., straight driving, acceleration, braking, and cornering were applied. For normal driving conditions no enhanced particle number concentration in the size range 6-562 nm was found. Unusual maneuvers associated with significant tire slip resulted in measurable particle concentrations. The maximum of the size distribution was between 30 and 60 nm. An exponential increase of the particle concentration with velocity was measured directly at the disc brakes for full stop brakings. A tracer gas experiment was carried out to estimate the upper limit of the emission factor during normal straight driving.

Mathissen, Marcel; Scheer, Volker; Vogt, Rainer; Benter, Thorsten

2011-11-01

120

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

121

Ultrafine particle removal and generation by portable air cleaners  

Microsoft Academic Search

Portable air cleaners can both remove and generate pollutants indoors. To investigate these phenomena, we conducted a two-phase investigation in a 14.75m3 stainless steel chamber. In the first phase, particle size-resolved (12.6–514nm diameter) clean air delivery rates (CADR) and efficiencies were determined, as were ozone emission rates, for two high-efficiency particle arresting (HEPA) filters, one electrostatic precipitator with a fan,

Michael S. Waring; Jeffrey A. Siegel; Richard L. Corsi

2008-01-01

122

Experimental investigation of submicron and ultrafine soot particle removal by tree leaves  

NASA Astrophysics Data System (ADS)

Soot particles emitted from vehicles are one of the major sources of air pollution in urban areas. In this study, five kinds of trees were selected as Pinus densiflora , Taxus cuspidata , Platanus occidentalis , Zelkova serrata , and Ginkgo biloba , and the removal of submicron (<1 ?m) and ultrafine (<0.1 ?m) soot particles by tree leaves was quantitatively compared in terms of deposition velocity. Soot particles were produced by a diffusion flame burner using acetylene as the fuel. The sizes of monodisperse soot particles classified with the Differential Mobility Analyzers (DMA) were 30, 55, 90, 150, 250, 400, and 600 nm. A deposition chamber was designed to simulate the omni-directional flow condition around the tree leaves. Deposition velocities onto the needle-leaf trees were higher than those onto the broadleaf trees. P. densiflora showed the greatest deposition velocity, followed by T. cuspidata , Platanus occidentalis , Zelkova serrata , and Ginkgo biloba . In addition, from the comparison of deposition velocity between two groups of Platanus occidentalis leaves, i.e. one group of leaves with front sides only and the other with back sides only, it was supposed in case of the broadleaf trees that the removal of airborne soot particles of submicron and ultrafine sizes could be affected by the surface roughness of tree leaves, i.e. the veins and other structures on the leaves.

Hwang, Hee-Jae; Yook, Se-Jin; Ahn, Kang-Ho

2011-12-01

123

Source Apportionment of Fine and Ultrafine Particles in California.  

National Technical Information Service (NTIS)

Source profiles for particles smaller than 0.1 microgram in diameter (PM0.1) were measured from light-duty gasoline-powered vehicles, heavy-duty diesel vehicles, pine wood combustion, oak wood combustion, eucalyptus wood combustion, rice straw combustion,...

M. J. Kleeman

2007-01-01

124

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, ...

125

Characteristics of metals in nano/ultrafine/fine/coarse particles collected beside a heavily trafficked road.  

PubMed

Fine particles emitted from vehicles have adverse health effects because of their sizes and chemical compositions. Therefore, this study attempted to characterize the metals in nano (0.010 < Dp < 0.056 microm), ultrafine (Dp < 0.1 microm), fine (Dp < 2.5 microm), and coarse (2.5 < Dp < 10 microm) particles collected near a busy road using a microorifice uniform deposition impactor (MOUDI) and a Nano-MOUDI. The nano particles were found to contain more of traffic-related metals (Pb, Cd, Cu, Zn, Ba, and Ni) than particles of other sizes, although crustal metals accounted for over 90% of all the particulate metals. Most crustal metals, Ba, Ni, Pb, and Zn in ultrafine particles displayed Aitken modes due to their local origins. The Ag, Cd, Cr, Ni, Pb, Sb, V, and Zn were 37, 50, 28, 30, 24, 64, 38, and 22% by mass, respectively, in < 0.1-microm particles, with submicron mass median diameters (MMDs) in PM(0.01-18) (except Zn) (particularly the < 0.1-microm MMDs for Cd and Sb). These levels raise potential health issues. Particle-bound Zn was more abundant in the accumulation mode than in the nucleation/condensation mode, but the opposite was true for Ag, Cd, and Sb. The Ag, Ba, Cd, Pb, Sb, V, and Zn contents in nano particles were strongly associated with diesel fuel, while the Cu, Mn, and Sr in particles < 0.1 microm were more strongly associated with gasoline. The high content of Si in nano particles, more associated with diesel soot than with gasoline exhaust, is another health concern. PMID:16294844

Lin, Chih-Chung; Chen, Shui-Jen; Huang, Kuo-Lin; Hwang, Wen-Ing; Chang-Chien, Guo-Ping; Lin, Wen-Yinn

2005-11-01

126

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

2012-07-22

127

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

SciTech Connect

In the previous reporting period, modifications were completed for integrating a continuous wax filtration system for a 4 liter slurry bubble column reactor. During the current reporting period, a shakedown of the system was completed. Several problems were encountered with the progressive cavity pump used to circulate the wax/catalyst slurry though the cross-flow filter element and reactor. During the activation of the catalyst with elevated temperature (> 270 C) the elastomer pump stator released sulfur thereby totally deactivating the iron-based catalyst. Difficulties in maintaining an acceptable leak rate from the pump seal and stator housing were also encountered. Consequently, the system leak rate exceeded the expected production rate of wax; therefore, no online filtration could be accomplished. Work continued regarding the characterization of ultra-fine catalyst structures. The effect of carbidation on the morphology of iron hydroxide oxide particles was the focus of the study during this reporting period. Oxidation of Fe (II) sulfate results in predominantly {gamma}-FeOOH particles which have a rod-shaped (nano-needles) crystalline structure. Carbidation of the prepared {gamma}-FeOOH with CO at atmospheric pressure produced iron carbides with spherical layered structure. HRTEM and EDS analysis revealed that carbidation of {gamma}-FeOOH particles changes the initial nano-needles morphology and generates ultrafine carbide particles with irregular spherical shape.

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

2006-09-30

128

Local deposition fractions of ultrafine particles in a human nasal-sinus cavity CFD model.  

PubMed

Ultrafine particle deposition studies in the human nasal cavity regions often omit the paranasal sinus regions. Because of the highly diffusive nature of nanoparticles, it is conjectured that deposition by diffusion may occur in the paranasal sinuses, which may affect the residual deposition fraction that leaves the nasal cavity. Two identical CFD models of a human nasal cavity, one with sinuses and one without, were reconstructed from CT-scans to determine the uptake of ultrafine particles. In general, there was little flow passing through the paranasal sinuses. However, flow patterns revealed that some streamlines reached the upper nasal cavity near the olfactory regions. These flow paths promote particle deposition in the sphenoid and ethmoid sinuses. It was found that there were some differences in the deposition fractions and patterns for 5 and 10 nm particles between the nasal-sinus and the nasal cavity models. This difference is amplified when the flow rate is decreased and at a flow rate of 4 L/min the maximum difference was 17%. It is suggested that evaluations of nanoparticle deposition should consider some deposition occurring in the paranasal sinuses especially if flow rates are of concern. PMID:22746399

Ge, Qin Jiang; Inthavong, Kiao; Tu, Ji Yuan

2012-07-01

129

High-frequency ferromagnetic resonance on ultrafine cobalt particles  

Microsoft Academic Search

We report on high-frequency (300-700 GHz) ferromagnetic resonance (HF-FMR) measurements on cobalt superparamagnetic particles with strong uniaxial effective anisotropy. We derive the dynamical susceptibility of the system on the basis of an independent-grain model by using a rectangular approach. Numerical simulations give typical line shapes depending on the anisotropy, the gyromagnetic ratio, and the damping constant. HF-FMR experiments have been

M. Respaud; M. Goiran; J. M. Broto; F. H. Yang; T. Ould Ely; C. Amiens; B. Chaudret

1999-01-01

130

Ultrafine Particle Deposition in a Human Tracheobronchial Cast  

Microsoft Academic Search

The deposition of 0.20, 0.15, and 0.04 ?m diameter particles was measured in a human central airway cast using a variable larynx with cyclic inspiratory flow. Data were compared with theoretical predictions for deposition from laminar flow for the first seven airway generations. With the exception of tracheal deposition, which on average exceeded predictions by a factor of 9, the

Beverly S. Cohen; Robert G. Sussman; Morton Lippmann

1990-01-01

131

Impact of two particle measurement techniques on the determination of N95 class respirator filtration performance against ultrafine particles.  

PubMed

The purpose of this experimental study was to compare two different particle measurement devices; an Electrical Low Pressure Impactor (ELPI) and a Scanning Mobility Particle Sizer (SMPS), to measure the number concentration and the size distribution of NaCl salt aerosols to determine the collection efficiency of filtering respirators against poly disperse aerosols. Tests were performed on NIOSH approved N95 filtering face-piece respirators (FFR), sealed on a manikin head. Ultrafine particles found in the aerosols were also collected and observed by transmission electron microscopy (TEM). According to the results, there is a systematic difference for the particle size distribution measured by the SMPS and the ELPI. It is largely attributed to the difference in the measurement techniques. However, in spite of these discrepancies, reasonably similar trends were found for the number concentration with both measuring instruments. The particle penetration, calculated based on mobility and aerodynamic diameters, never exceeded 5% for any size range measured at constant flow rate of 85 L/min. Also, the most penetrating particle size (MPPS), with the lowest filtration efficiency, would occur at a similar ultrafine size range <100 nm. With the ELPI, the MPPS was at 70 nm aerodynamic diameter, whereas it occurred at 40 nm mobility diameter with the SMPS. PMID:22464753

Mostofi, Reza; Noël, Alexandra; Haghighat, Fariborz; Bahloul, Ali; Lara, Jaime; Cloutier, Yves

2012-03-02

132

Effect of interparticle forces on the coagulation of ultrafine SiO2 particles  

NASA Astrophysics Data System (ADS)

The mechanism of ultrafine (2 particle production under thermal arc plasma conditions is studied by modelling. Two cases of the process are considered in the model: (i) when it is determined as a pure free-molecular coagulation; (ii) when the coagulation is influenced by the interparticle forces. The Hamaker formula is used to present the van der Waals forces between the particles. Particle size distribution functions (PSDF) are calculated for both cases. It is shown that inclusion of the interparticle interactions does not affect the self-preservation of the PSDF. The mean particle sizes are obtained from the PSDF and compared. Higher values are observed in the case that includes van der Waals forces. Comparison between experimental and calculated PSDF shows better agreement in the case considering interparticle forces.

Balabanova, E.; Oliver, D.

1996-09-01

133

Ultrafine Sm-Fe-N Particles Prepared by Planetary Ball Milling  

NASA Astrophysics Data System (ADS)

Ultrafine magnetically hard particles are needed for the bottom­up fabrication of anisotropic exchanged­coupled permanent magnets. In this study we have chosen Sm2Fe17Nx because of its high anisotropy field and large saturation magnetization. A multi­stage planetary ball milling process was used. The key is to find the right balance of energy used to mill the precursor particles; it must be high enough to break the particles and reduce their size but, not so high as to destroy the crystal structure of the nanoparticles that would lead to deterioration of the magnetic properties. First the coarse powders were subjected to a wet milling with 2.0 mm diameter media. In each subsequent stage the media size was reduced to maintain the milling balance. Using such a process produced particles in a size range from 100 - 800 nm with a coercivity as high as 10 kOe at room temperature.

Hadjipanayis, G.; Neil, D.; Gabay, A.

2013-01-01

134

The measurement of ultrafine particles: A pilot study using a portable particle counting technique to measure generated particles during a micromachining process  

Microsoft Academic Search

The accurate measurement of airborne particles in the nanometer range is a challenging task. Because several studies have\\u000a linked exposures to airborne ultrafine particles to elevated human health risks, the need to assess the concentrations of\\u000a particles in the workplace that are below 100 nm in diameter is imperative. Several different techniques for monitoring nanoparticles\\u000a are now available, and others

Rodney G. Handy; Mark J. Jackson; Grant M. Robinson; Michael D. Lafreniere

2006-01-01

135

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

136

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

137

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

2012-06-23

138

Theoretical constraints on pure vapor-pressure driven condensation of organics to ultrafine particles  

NASA Astrophysics Data System (ADS)

Organic condensation to freshly nucleated particles contributes substantially to their growth. Here we explore a range of constraints on this process, under the assumption that gas-phase oxidation of organic vapors by hydroxy radical is forming organics with a sufficiently low volatility to condense onto particles in the 2-20 nm size range. To condense but not homogeneously nucleate, vapors need to have saturation concentrations (C*) in the 10-3 - 10-2 ?g m-3 range, and this is exactly the range that gas-phase chemistry is likely to produce. At least half of the observed growth rate of ultrafine particles can be explained by these simple considerations and constraints.

Donahue, N. M.; Trump, E. R.; Pierce, J. R.; Riipinen, I.

2011-08-01

139

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

2009-11-11

140

Ultrafine particles in indoor air of a school: possible role of secondary organic aerosols.  

PubMed

The aim of this work was to investigate ultrafine particles (<0.1 microm) in primary school classrooms, in relation to the classroom activities. The investigations were conducted in three classrooms during two measuring campaigns, which together encompassed a period of 60 days. Initial investigations showed that under the normal operating conditions of the school there were many occasions in all three classrooms where indoor particle concentrations increased significantly compared to outdoor levels. By far the highest increases in the classroom resulted from art activities (painting, gluing, and drawing), at times reaching over 1.4 x 10(5) particle cm(-3). The indoor particle concentrations exceeded outdoor concentrations by approximately 1 order of magnitude, with a count median diameter ranging from 20 to 50 nm. Significant increases also occurred during cleaning activities, when detergents were used. GC-MS analysis conducted on 4 samples randomly selected from about 30 different paints and glues, as well as the detergent used in the school, showed that d-limonene was one of the main organic compounds of the detergent, however, it was not detected in the samples of the paints and the glue. Controlled experiments showed that this monoterpene, emitted from the detergent, reacted with O(3) (at outdoor ambient concentrations ranging from 0.06 to 0.08 ppm) and formed secondary organic aerosols. Further investigations to identify other liquids that may be potential sources of the precursors of secondary organic aerosols were outside the scope of this project, however, it is expected that the problem identified by this study could be more widely spread, since most primary schools use liquid materials for art classes, and all schools use detergents for cleaning. Further studies are therefore recommended to better understand this phenomenon and also to minimize exposure of school children to ultrafine particles from these indoor sources. PMID:20000499

Morawska, Lidia; He, Congrong; Johnson, Graham; Guo, Hai; Uhde, Erik; Ayoko, Godwin

2009-12-15

141

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

142

Synthesis of ultrafine single-component oxide particles by the spray-ICP technique  

Microsoft Academic Search

Ultrafine oxide particles were synthesized by introducing aqueous solutions of metal salts into a high-temperature r.f. inductively\\u000a coupled plasma (the spray-ICP technique). The particles synthesized were spherical for ZrO2, Y2O3, Sm2O3, La2O3, ?-Al2O3, TiO2 (anatase), ?-Bi2O3 and CuO, plate-like for Nd3O2, Cr2O3 and Pr2O3, polyhedral for PrO2, CeO2 and ?-Fe2O3, cubical for NiO, MgO, CaO, Co3O4 and Mn3O4, bar-like for

M. Suzuki; M. Kagawa; Y. Syono; T. Hirai

1992-01-01

143

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

144

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...

145

Size Distribution and Diurnal and Seasonal Trends of Ultrafine Particles in Source and Receptor Sites of the Los Angeles Basin  

Microsoft Academic Search

This paper presents results from a study conducted in two urban areas of southern California, Downey and Riverside, to examine the effect of different sources and formation mechanisms on the size distribution and temporal trends of ultrafine particles. Near-continuous data were collected for 5 months at each location. Our data clearly identified Downey as a source site, primarily affected by

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

2002-01-01

146

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

SciTech Connect

Highlights: > Particle size distributions and total concentrations measurement at the stack and before the fabric filter of an incinerator. > Chemical characterization of UFPs in terms of heavy metal concentration through a nuclear method. > Mineralogical investigation through a Transmission Electron Microscope equipped with an Energy Dispersive Spectrometer. > Heavy metal concentrations on UFPs as function of the boiling temperature. > Different mineralogical and morphological composition amongst samples collected before the fabric filter and at the stack. - Abstract: 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 {mu}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 x 10{sup 7} part. cm{sup -3} and 2.0 x 10{sup 3} part. cm{sup -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.

Buonanno, Giorgio, E-mail: buonanno@unicas.it [University of Cassino, via G. Di Biasio 43, 03043 Cassino (Italy); Stabile, Luca [University of Cassino, via G. Di Biasio 43, 03043 Cassino (Italy); Avino, Pasquale [DIPIA, INAIL (ex-ISPESL), via Urbana 167, 00184 Rome (Italy); Belluso, Elena [Dipartimento di Scienze Mineralogiche e Petrologiche, University of Torino and Institute of Geosciences and Earth Resources, CNR-Unita di Torino, via Valperga Caluso 35, 10125 Torino (Italy)

2011-11-15

147

Apportionment of motor vehicle emissions from fast changes in number concentration and chemical composition of ultrafine particles near a roadway intersection.  

PubMed

High frequency spikes in ultrafine number concentration near a roadway intersection arise from motor vehicles that accelerate after a red light turns green. The present work describes a method to determine the contribution of motor vehicles to the total ambient ultrafine particle mass by correlating these number concentration spikes with fast changes in ultrafine particle chemical composition measured with the nano aerosol mass spectrometer, NAMS. Measurements were performed at an urban air quality monitoring site in Wilmington, Delaware during the summer and winter of 2009. Motor vehicles were found to contribute 48% of the ultrafine particle mass in the winter measurement period, but only 16% of the ultrafine particle mass in the summer period. Chemical composition profiles and contributions to the ultrafine particle mass of spark vs diesel vehicles were estimated by correlating still camera images, chemical composition and spike contribution at each time interval.. The spark and diesel contributions were roughly equal, but the uncertainty in the split was large. The distribution of emissions from individual vehicles was determined by correlating camera images with the spike contribution to particle number concentration at each time interval. A small percentage of motor vehicles were found to emit a disproportionally large concentration of ultrafine particles, and these high emitters included both spark ignition and diesel vehicles. PMID:21667963

Klems, Joseph P; Pennington, M Ross; Zordan, Christopher A; McFadden, Lauren; Johnston, Murray V

2011-06-13

148

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

2011-07-29

149

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

150

Indoor and outdoor concentrations of ultrafine particles in some Scandinavian rural and urban areas.  

PubMed

The concentration of ultrafine particles (0.01 to greater than 1 microm) was measured in some rural and urban areas of Sweden and Denmark. The instruments used are handheld real-time condensation particle counters, models CPC 3007 and P-Trak 8525, both manufactured by TSI. Field measurements in Sweden were conducted in a few residential and office buildings, while in Denmark the measurement sites comprised two office buildings, one of them located in a rural area. The concentration of UFPs was measured simultaneously indoors and outdoors with condensation particle counters. The results revealed that the outdoor-generated particle levels were major contributors to the indoor particle number concentration in the studied buildings when no strong internal source was present. The results showed that in office buildings, the UFP concentrations indoors were typically lower and correlated fairly well to the number concentration outdoors. The determined indoor-outdoor ratios varied between 0.5 and 0.8. The indoor levels of UFPs in offices where smoking is allowed was sometimes recorded higher than outdoor levels, as in one of the Danish offices. In residential buildings, the indoor number concentration was strongly influenced by several indoor activities, e.g., cooking and candle burning. In the presence of significant indoor sources, the indoor/outdoor (IO) ratio exceeded unity. The magnitude of UFP concentrations was greater in the large city of Copenhagen compared to the medium-size city of Gothenburg and lowest at more rural sites. PMID:15862843

Matson, Uve

2004-11-14

151

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

152

Characteristic study of ionic species in nano, ultrafine, fine and coarse particle size mode at a traffic sampling site.  

PubMed

A micro-orifice uniform deposit impactor (MOUDI) and a nano-MOUDI were used to measure the atmospheric coarse (PM2.5-10), fine (PM2.5), ultrafine (PM0.056-1) and nano (<0.056 microm) particle concentrations at a traffic sampling site in central Taiwan during the winter period from November 2004 to January 2005. Meanwhile, concentrations of major ionic species (Cl-, NO3-, SO(2-)4, NH4+, Na+, K+, Ca2+ and Mg2+) were also extracted from various particle size modes (nano, ultrafine, fine and coarse) and analysed by ion chromatography (DIONEX-100). The mass size distribution of ambient suspended particles exhibited two modes. The size ranges of the particles at these two particle size modes were between 1.0 and 1.8 microm and 3.2 and 5.6 microm, respectively. The average mass media aerodynamic diameter (MMAD) of suspended particles was 0.99 microm in this study. In addition, statistical methods, such as correlation coefficient and principal component analysis, were also used to identify the possible pollutant source for various particles size modes (nano, ultrafine, fine and coarse) during the winter months at a traffic sampling site in central Taiwan. PMID:16572709

Fang, Guor-Cheng; Wu, Yuh-Shen; Chang, Shih-Yo; Rau, Jui-Yeh; Huang, Shih-Han; Lin, Chi-Kwong

2006-02-01

153

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

154

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 (PM2.5, SO2, CO and O3) 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 SO2 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 SO2-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

155

PM 10 and Ultrafine Particles Counts In-Vehicle and On-Road in the Athens Area  

Microsoft Academic Search

This work presents the first results of a study concerning on-road and in-vehicle exposure to particulate matter in the area\\u000a of Athens. PM10 concentration measurements were conducted by TSI DustTrak, while driving along routes with different characteristics of traffic\\u000a density, during September 2003–March 2004. Concurrent measurements of the ultrafine particles (UFPs) number concentration\\u000a were also conducted, by condensation particle counter

E. Diapouli; G. Grivas; A. Chaloulakou; N. Spyrellis

2008-01-01

156

Indoor Sources of Ultrafine and Accumulation Mode Particles: Size Distributions, Size-Resolved Concentrations, and Source Strengths  

Microsoft Academic Search

Ultrafine (< 100 nm) and accumulation mode (0.1–1 ?m) particles were monitored in an occupied suburban house at 5-minute intervals for 37 consecutive months between November 21, 1997 and December 31, 2000. Number concentrations for 126 particle sizes from 9.8–947 nm were measured in 259,176 scans. Of 282 separate activities, 18 were chosen for detailed analysis. These included cooking with

Lance Wallace

2006-01-01

157

Measurement of ultrafine particle size distributions from coal-, oil-, and gas-fired stationary combustion sources.  

PubMed

Currently, we have limited knowledge of the physical and chemical properties of emitted primary combustion aerosols and the changes in those properties caused by nucleation, condensation growth of volatile species, and particle coagulations under dilution and cooling in the ambient air. A dilution chamber was deployed to sample exhaust from a pilot-scale furnace burning various fuels at a nominal heat input rate of 160 kW/h(-1) and 3% excess oxygen. The formation mechanisms of particles smaller than 420 nm in electrical mobility diameter were experimentally investigated by measurement with a Scanning Mobility Particle Sizer (SMPS) as a function of aging times, dilution air ratios, combustion exhaust temperatures, and fuel types. Particle formation in the dilution process is a complex mixture of nucleation, coagulation, and condensational growth, depending on the concentrations of available condensable species and solid or liquid particles (such as soot, ash) in combustion exhausts. The measured particle size distributions in number concentrations measured show peaks of particle number concentrations for medium sulfur bituminous coal, No. 6 fuel oil, and natural gas at 40-50 nm, 70-100 nm, and 15-25 nm, respectively. For No. 6 fuel oil and coal, the particle number concentration is constant in the range of a dilution air ratio of 50, but the number decreases as the dilution air ratio decreases to 10. However, for natural gas, the particle number concentration is higher at a dilution air ratio of 10 and decreases at dilution air ratios of 20-50. At a dilution air ratio of 10, severe particle coagulation occurs in a relatively short time. Samples taken at different combustion exhaust temperatures for these fuel types show higher particle number concentrations at 645 K than at 450 K. As the aging time of particles increases, the particles increase in size and the number concentrations decrease. The largest gradient of particle number distribution occurs within the first 10 sec after dilution but shows only minor differences between 10 and 80 sec. The lifetimes of the ultrafine particles are relatively short, with a scale on the order of a few seconds. Results from this study suggest that an aging time of 10 sec and a dilution air ratio of 20 are sufficient to obtain representative primary particle emission samples from stationary combustion sources. PMID:15648387

Chang, M C Oliver; Chow, Judith C; Watson, John G; Hopke, Philip K; Yi, Seung-Muk; England, Glenn C

2004-12-01

158

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

159

Using the Aerasense NanoTracer for simultaneously obtaining several ultrafine particle exposure metrics  

NASA Astrophysics Data System (ADS)

The expanding production and use of nanomaterials increases the chance of human exposure to engineered nanoparticles (NP), also referred to as ultrafine particles (UFP; <= 100 - 300 nm). This is particularly true in workplaces where they can become airborne and thereafter inhaled by workers during nanopowder processing. Considering the suspected hazard of many engineered UFPs, the general recommendation is to take measures for minimizing personal exposure while monitoring the UFP pollution for assessment and control purposes. The portable Aerasense NanoTracer accomplishes this UFP monitoring, either intermittently or in real time. This paper reviews its design and operational characteristics and elaborates on a number of application extensions and constraints. The NanoTracer's output signals enable several UFP exposure metrics to be simultaneously inferred. These include the airborne UFP number concentration and the number-averaged particle size, serving as characteristics of the pertaining UFP pollution. When non-hygroscopic particles are involved, the NanoTracer's output signals also allow an estimation of the lung-deposited UFP surface area concentration and the lung-deposited UFP mass concentration. It is thereby possible to distinguish between UFP depositions in the alveolar region, the trachea-bronchial region and the head airway region, respectively, by making use of the ICRP particle deposition model.

Marra, J.

2011-07-01

160

Commuter exposure to ultrafine particles in different urban locations, transportation modes and routes  

NASA Astrophysics Data System (ADS)

A better understanding of ultrafine particle (UFP) exposure in different urban transport microenvironments is important for epidemiological exposure assessments and for policy making.Three sub-studies were performed to characterize personal exposure to UFP concentration and average particle size distribution diameters in frequently traveled commuter microenvironments in the city of Basel, Switzerland. First, the spatial variation of sidewalk UFP exposures within urban areas and transport-specific microenvironments was explored. Second, exposure to UFP concentration and average particle size were quantified for five modes of transportation (walking, bicycle, bus, tram, car) during different times of the day and week, along the same route. Finally, the contribution of bicycle commuting along two different routes (along main roads, away from main roads) to total daily exposures was assessed by 24-h personal measurements.In general, smaller average particle sizes and higher UFP levels were measured at places and for travel modes in close proximity to traffic. Average trip UFP concentrations were higher in car (31,784 particles cm?³) and on bicycle (22,660 particles cm?³) compared to walking (19,481 particles cm?³) and public transportation (14,055–18,818 particles cm?³). Concentrations were highest for all travel modes during weekday morning rush hours, compared to other time periods. UFP concentration was lowest in bus, regardless of time period. Bicycle travel along main streets between home and work place (24 min on average) contributed 21% and 5% to total daily UFP exposure in winter and summer, respectively. Contribution of bicycle commutes to total daily UFP exposure could be reduced by half if main roads are avoided.Our results show the importance of considering commuter behavior and route choice in exposure assessment studies.

Ragettli, Martina S.; Corradi, Elisabetta; Braun-Fahrländer, Charlotte; Schindler, Christian; de Nazelle, Audrey; Jerrett, Michael; Ducret-Stich, Regina E.; Künzli, Nino; Phuleria, Harish C.

2013-10-01

161

The Effects of Leaf Area Density Variation on the Particle Collection Efficiency in the Size Range of Ultrafine Particles (UFP).  

PubMed

Carbonaceous particles were generated during a "sooting burn" experiment to explore how heterogeneity in horizontal leaf area density (LAD) within the canopy impacts the ultrafine particle (UFP) collection efficiency at the branch-scale. To address this goal, wind tunnel experiments and a particle-size resolving model, which couples the turbulent flow field within the vegetated volume and the collection efficiency, were presented. Three scenarios were examined in a wind-tunnel packed with Juniperus chinensis branches: An LAD that was uniformly distributed, linearly increasing and linearly decreasing along the longitudinal or mean wind direction. The concentration measurements were conducted at multiple locations within the vegetated volume to evaluate the performance of the proposed model needed in discerning the role of LAD heterogeneity on UFP collection. Differences not exceeding 20% were found between modeled and measured concentration for all particle sizes across a wide range of wind speeds. The overall particle collection efficiency was found to be primarily governed by the spatially integrated LAD when differences in aerodynamic attributes (e.g., foliage drag) were accounted for. When combined with earlier studies, the results suggest that one parameter linking the laminar boundary layer conductance to the Schmidt number depends on particle size. PMID:24001338

Huang, Cheng-Wei; Lin, Ming-Yeng; Khlystov, Andrey; Katul, Gabriel

2013-10-07

162

Effects of exposure to ultrafine carbon particles in healthy subjects and subjects with asthma.  

PubMed

Increased levels of particulate air pollution are associated with increased respiratory and cardiovascular mortality and morbidity as well as worsening of asthma. Ultrafine particles (UFP; less than 0.1 microm in aerodynamic diameter) may contribute to the health effects of particulate matter (PM) for a number of reasons. Compared with larger particles on a mass basis, UFP have a higher predicted pulmonary deposition, greater potential to induce pulmonary inflammation, larger surface area, and enhanced oxidant capacity. UFP also have the potential to cross the epithelium and enter the systemic circulation. We hypothesized that exposure to UFP causes airway inflammation in susceptible humans with activation of circulating leukocytes and vascular endothelium, a systemic acute phase response, and transient hypercoagulability. We further hypothesized that in people with asthma, UFP deposition would be increased and underlying airway inflammation enhanced. Our objectives were: to develop a system for controlled exposures of humans to UFP; to measure the pulmonary fractional deposition of UFP; to assess the effects of UFP exposure on blood leukocyte and endothelial adhesion molecule expression and activation, on airway nitric oxide (NO) production, on the systemic acute phase response, on blood coagulability, and on cardiac electrical activity and repolarization; and to evaluate these responses in both healthy subjects and people with asthma. We developed and validated a mouthpiece exposure system for human studies of carbon UFP and then conducted three clinical exposure studies: healthy subjects breathing filtered air and UFP (10 microg/m3) at rest (UPREST); healthy subjects breathing air and UFP (10 and 25 microg/m3) with intermittent exercise (UPDOSE); and subjects with mild asthma breathing air and UFP (10 microg/m3) with intermittent exercise (UPASTHMA). All exposures were for 2 hours on the mouthpiece system. Exposures were separated by at least 2 (UPREST and UPDOSE) or 3 (UPASTHMA) weeks. Prior to and at intervals after each exposure, we assessed symptoms, pulmonary function, blood markers of inflammation and coagulation, and airway NO production. Sputum inflammatory cells were assessed 21 hours after exposure. Continuous 12-lead electrocardiography (ECG) recordings were analyzed for changes in heart rate variability, repolarization, and arrhythmias. For healthy subjects, the fractional deposition of UFP at rest was 0.66 +/- 0.11 (mean +/- SD) by particle number, confirming the high deposition for UFP predicted by models. Deposition further increased during exercise (0.83 +/- 0.04). Asthmatic subjects showed higher UFP deposition than did healthy subjects when breathing at rest (0.76 +/- 0.05). During the UPREST protocol, there were no convincing effects for any outcome measures. Breathing 25 microg/m3 UFP with exercise (UPDOSE) was associated with reductions in blood monocytes and activation of T lymphocytes in healthy females. In asthmatic subjects (UPASTHMA), breathing 10 microg/m3 UFP was associated with reduced numbers of blood eosinophils and CD4+ T lymphocytes. In the UPDOSE group, monocyte expression of intercellular adhesion molecule-1 (ICAM-1) was reduced in a concentration-related manner (P = 0.001). In the UPASTHMA group, CD11b expression was reduced on monocytes and eosinophils, and ICAM-1 expression was reduced on polymorphonuclear leukocytes (PMNs). ECG analyses of UPDOSE subjects showed transient reductions in parasympathetic influence on heart rate variability and a reduced repolarization (QT) interval. In UPASTHMA subjects, ECG analyses showed decreased QT variability, but no effect on the QT interval. There were no significant effects in any of the studies on symptoms, pulmonary function, or markers of airway inflammation. We found no increases in soluble markers of systemic inflammation or coagulation. Our hypothesis that inhalation of carbon UFP causes pulmonary inflammation and an acute phase response was not confirmed. However, the observed subtle changes in leukocyte subsets and adhesion molecule

Frampton, Mark W; Utell, Mark J; Zareba, Wojciech; Oberdörster, Günter; Cox, Christopher; Huang, Li-Shan; Morrow, Paul E; Lee, F Eun-Hyung; Chalupa, David; Frasier, Lauren M; Speers, Donna M; Stewart, Judith

2004-12-01

163

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. In the first quarterly report for this program the concept behind our approach was detailed, the structure of the program was presented, key technical issues were identified, preliminary designs were outlined, and technical progress was discussed. All progress made during the second quarter of this program related to experiment design of the proposed supercritical expansion technique for generating ultra-fine, iron compound, catalyst particles. This second quarterly report, therefore, presents descriptions of the final designs for most system components; diagnostic approaches and designs for determining particles size and size distributions, and the composition of the pre-expansion supercritical solution; and the overall technique progress made during this reporting period. 6 refs., 15 figs., 1 tab.

Not Available

1991-09-01

164

Contrasting macrophage activation by fine and ultrafine titanium dioxide particles is associated with different uptake mechanisms  

PubMed Central

Inhalation of (nano)particles may lead to pulmonary inflammation. However, the precise mechanisms of particle uptake and generation of inflammatory mediators by alveolar macrophages (AM) are still poorly understood. The aim of this study was to investigate the interactions between particles and AM and their associated pro-inflammatory effects in relation to particle size and physico-chemical properties. NR8383 rat lung AM were treated with ultrafine (uf), fine (f) TiO2 or fine crystalline silica (DQ12 quartz). Physico-chemical particle properties were investigated by transmission electron microscopy, elemental analysis and thermogravimetry. Aggregation and agglomeration tendency of the particles were determined in assay-specific suspensions by means of dynamic light scattering. All three particle types were rapidly taken up by AM. DQ12 and ufTiO2 , but not fTiO2 , caused increased extracellular reactive oxygen species (ROS), heme oxygenase 1 (HO-1) mRNA expression and tumor necrosis factor (TNF)-? release. Inducible nitric oxide synthase (iNOS) mRNA expression was increased most strongly by ufTiO2 , while DQ12 exclusively triggered interleukin (IL) 1? release. However, oscillations of intracellular calcium concentration and increased intracellular ROS were observed with all three samples. Uptake inhibition experiments with cytochalasin D, chlorpromazine and a Fc? receptor II (Fc?RII) antibody revealed that the endocytosis of fTiO2 by the macrophages involves actin-dependent phagocytosis and macropinocytosis as well as clathrin-coated pit formation, whereas the uptake of ufTiO2 was dominated by Fc?IIR. The uptake of DQ12 was found to be significantly reduced by all three inhibitors. Our findings suggest that the contrasting AM responses to fTiO2 , ufTiO2 and DQ12 relate to differences in the involvement of specific uptake mechanisms.

2011-01-01

165

Ultrafine particle and fine trace metal (As, Cd, Cu, Pb and Zn) pollution episodes induced by industrial emissions in Huelva, SW Spain  

NASA Astrophysics Data System (ADS)

Urban air quality impairment by ultrafine particles has become a matter of concern due to the adverse effects on human health. Most of the studies of ultrafine particles in urban air quality have focused on vehicle exhaust emissions. We studied how industrial emissions contribute to ultrafine particle concentrations in downwind urban ambient air. This research is based on experimental data collected in the ambient air of the industrial city of Huelva (SW Spain) over April 2008-December 2009 period (particle number, gaseous pollutants and black carbon concentrations and levels and chemical composition of PM10 and PM2.5 with daily and hourly resolution). This city is affected by emissions from the second largest Cu-smelter in Europe, phosphoric acid and fertilizer production plants and an oil refinery and petrochemical plant. Industrial emissions are the main cause of ultrafine particle episodes. When vehicle exhaust emissions are the main source, ultrafine particles typically show (24-h mean) concentrations within the range 14,700-5000 cm-3 (50th-1st), with 60% of these linked to this source and 30% to industrial emissions. In contrast, when daily mean levels of N are within the range 50,000-25,500 cm-3 (100th-70th), industrial and vehicle exhaust emissions accounted for 49 and 30%, respectively. High concentrations of toxic trace metals (As, Cu, Cd, Zn and Pb) were recorded when the study city suffered fumigations of the Cu-smelter plumes (e.g. 10-25 ng m-3 As, 1-2 ng m-3 Cd and >105 cm-3 of ultrafine particles). Because of these industrial emissions, ultrafine particle concentrations during daylight are about two times higher than those observed in other European cities. Recently, ultrafine particle emissions in vehicle exhausts have been subject to limit values in a recent stage of the EURO standards. Industrial emissions should also be considered.

Fernández-Camacho, R.; Rodríguez, S.; de la Rosa, J.; Sánchez de la Campa, A. M.; Alastuey, A.; Querol, X.; González-Castanedo, Y.; Garcia-Orellana, I.; Nava, S.

2012-12-01

166

Ultrafine particle concentrations and exposures in four high-rise Beijing apartments  

NASA Astrophysics Data System (ADS)

Ultrafine particle (UFP) exposures have the potential to elicit adverse health effects. People spend most of their time within their place of residence. Little information is available on UFP levels in homes in mainland China. To contribute new data to this important topic, we made time-series measurements of particle number (PN) concentrations and resident activities inside four apartments in high-rise buildings in Beijing during June to August 2009. Indoor PN concentrations at the four sites, averaged over the few-day duration of monitoring at each site, spanned an order of magnitude, from 2800 to 29,100 cm-3. This wide range resulted from differences among apartments in three main factors: (1) the frequency of indoor source events, including cooking activities and intrusion of cooking exhaust from neighboring apartments; (2) the extent of natural ventilation via open windows; and (3) the extent of active air filtration. Daily-integrated PN exposure of the thirteen residents, while in their apartments, ranged from 45,000 to 494,000 cm-3 h/d. For two sites at which outdoor PN concentrations were also measured, the percentage of daily-integrated residential exposure attributable to particles of outdoor origin was 58% for the residents of one site and 81% for residents of the other.

Mullen, Nasim A.; Liu, Cong; Zhang, Yinping; Wang, Shuxiao; Nazaroff, William W.

2011-12-01

167

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

168

Production, growth and properties of ultrafine atmospheric aerosol particles in an urban environment  

NASA Astrophysics Data System (ADS)

Number concentrations of atmospheric aerosol particles were measured by a flow-switching type differential mobility particle sizer in an electrical mobility diameter range of 6-1000 nm in 30 channels near central Budapest with a time resolution of 10 min continuously from 3 November 2008 to 2 November 2009. Daily median number concentrations of particles varied from 3.8×103 to 29×103 cm-3 with a yearly median of 11.8×103 cm-3. Contribution of ultrafine particles to the total particle number ranged from 58 to 92% with a mean ratio and standard deviation of (79±6)%. Daily average number concentrations in various size fractions and contribution of ultrafine particles to the total particle number showed no seasonal dependency. Monthly mean number size distributions were similar to each other. Overall mean for the number median mobility diameter of the Aitken and accumulation modes were 26 and 93 nm, respectively, which are substantially smaller than for rural or background environments. The Aitken and accumulation modes contributed similarly to the total particle number concentrations at the actual measurement location. Median diameters of the Aitken and accumulation modes were shifted to larger values before nucleation started and over the growth process, which can be related to the presence of aged aerosol under the conditions that favour nucleation and growth. Particle concentrations were usually increased substantially after nucleations. Overall mean and standard deviation of the nucleation mode number concentrations were (10.4±2.8)×103 cm-3. Mean ratio and standard deviation of the nucleation mode number concentration to the total particle number concentration that was averaged for two hours just before the formation was detected was 2.3±1.1. Nucleation unambiguously occurred on 83 days, which represent 27% of all relevant days. Its frequency showed a remarkable seasonal variation with a minimum of 7.3% in winter and a maximum of 44% in spring. Formation rate of particles with a diameter of 6 nm varied between 1.65 and 12.5 cm-3 s-1 with a mean and standard deviation of (4.2±2.5) cm-3 s-1. Seasonal dependency for the formation rate could not be identified. Growth curves of nucleated particles were usually superimposed on the characteristic diurnal pattern of road traffic direct emissions. The growth rate of the nucleation mode with a median diameter of 6 nm varied from 2.0 to 13.3 nm h-1 with a mean and standard deviation of (7.7±2.4) nm h-1. There was an indicative tendency for larger growth rates in summer and for smaller values in winter. Several indirect evidences suggest that the nucleation events occurred at least over the whole city, and were of regional type.

Salma, I.; Borsós, T.; Weidinger, T.; Aalto, P.; Hussein, T.; Dal Maso, M.; Kulmala, M.

2010-06-01

169

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

170

Observations of ultrafine particle nucleation events in the tropical UT/LS over West Africa and Brazil  

NASA Astrophysics Data System (ADS)

New particle formation by gas to particle conversion in the tropical upper troposphere and lower stratosphere (UT/LS) may be a major source of aerosols for origin and maintenance of the global stratospheric Junge aerosol layer. Once created in the tropical upper troposphere these ultrafine particles can be carried aloft towards the tropopause by the -radiatively driven- slowly rising air, and subsequently enter the Brewer-Dobson circulation for global distribution within the stratosphere. During the TROCCINOX (2005) and AMMA-SCOUT (2006) campaigns in South America (Brazil) and West-Africa (Burkina Faso) the Russian M-55 high altitude research aircraft "Geophysica" performed in-situ measurements of trace gases and aerosols in the tropical UT/LS. By means of the four channel COPAS condensation particle counting system total ultrafine particle number concentrations were measured for ambient aerosol particles with size diameters larger than 6 nm, 10 nm, and 14 nm, respectively. The fourth channel also had a lower "cut-off" diameter of 10 nm, but here the sample air was heated to 250 °C prior to the particle detection. Thus, this channel delivered the number of non volatile particles providing information on the fraction of particles NOT consisting of binary sulfuric acid/water solutions. During both campaigns cloud free air masses were encountered between 12 and 14 km altitude with ultrafine particle concentrations as high as 8000 to 10000 particles per cm³. Based on the difference of the count results from the channels with 6 nm and 14 nm cut-off diameters it can be concluded that the particles were freshly formed in-situ during so called nucleation events. Covering flight path lengths of roughly 300 km over West-Africa and 600 km over Brazil these areas with enhanced particle concentrations are of significant scale. For the data observed over Brazil oxidation of ground released SO2 to H2SO4 while being lifted -possibly supported by ion induced nucleation- is a likely explanation. By contrast, for the nucleation event over West-Africa trajectory analyses, as well as correlations with in-situ CO measurements indicate biomass burning as possible source of the gases for the gas-to-particle conversion processes underlying this particular event. In the presentation the "Geophysica" data sets and their differences are shown, and comparisons with tropical data from the literature are provided. Furthermore, the data from the observed nucleation events are juxtaposed with the measured results of background ultrafine aerosol particle concentrations. Here the differences in non-volatile fractions of the UT/LS aerosol over Brazil and West Africa are highlighted, and compared to corresponding measurements over Darwin, Australia, during SCOUT-O3 in 2005.

Borrmann, S.; Curtius, J.; Kunkel, D.; Weigel, R.; Vicani, S.; Schiller, C.; Ulanovski, A.; Ravegnani, F.; Cairo, F.; Law, K. A.

2009-04-01

171

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

172

Children exposure assessment to ultrafine particles and black carbon: The role of transport and cooking activities  

NASA Astrophysics Data System (ADS)

An accurate evaluation of the airborne particle dose-response relationship requires detailed measurements of the actual particle concentration levels that people are exposed to, in every microenvironment in which they reside. The aim of this work was to perform an exposure assessment of children in relation to two different aerosol species: ultrafine particles (UFPs) and black carbon (BC). To this purpose, personal exposure measurements, in terms of UFP and BC concentrations, were performed on 103 children aged 8-11 years (10.1 ± 1.1 years) using hand-held particle counters and aethalometers. Simultaneously, a time-activity diary and a portable GPS were used to determine the children's daily time-activity pattern and estimate their inhaled dose of UFPs and BC. The median concentration to which the study population was exposed was found to be comparable to the high levels typically detected in urban traffic microenvironments, in terms of both particle number (2.2 × 104 part. cm-3) and BC (3.8 ?g m-3) concentrations. Daily inhaled doses were also found to be relatively high and were equal to 3.35 × 1011 part. day-1 and 3.92 × 101 ?g day-1 for UFPs and BC, respectively. Cooking and using transportation were recognized as the main activities contributing to overall daily exposure, when normalized according to their corresponding time contribution for UFPs and BC, respectively. Therefore, UFPs and BC could represent tracers of children exposure to particulate pollution from indoor cooking activities and transportation microenvironments, respectively.

Buonanno, G.; Stabile, L.; Morawska, L.; Russi, A.

2013-11-01

173

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

174

Ultrafine particles from diesel engines induce vascular oxidative stress via JNK activation.  

PubMed

Exposure to particulate air pollution is linked to increased incidences of cardiovascular diseases. Ambient ultrafine particles (UFP) from diesel vehicle engines have been shown to be proatherogenic in ApoE knockout mice and may constitute a major cardiovascular risk in humans. We posited that circulating nano-sized particles from traffic pollution sources induce vascular oxidative stress via JNK activation in endothelial cells. Diesel UFP were collected from a 1998 Kenworth truck. Intracellular superoxide assay revealed that these UFP dose-dependently induced superoxide (O(2)(-)) production in human aortic endothelial cells (HAEC). Flow cytometry showed that UFP increased MitoSOX red intensity specific for mitochondrial superoxide. Protein carbonyl content was increased by UFP as an indication of vascular oxidative stress. UFP also up-regulated heme oxygenase-1 (HO-1) and tissue factor (TF) mRNA expression, and pretreatment with the antioxidant N-acetylcysteine significantly decreased their expression. Furthermore, UFP transiently activated JNK in HAEC. Treatment with the JNK inhibitor SP600125 and silencing of both JNK1 and JNK2 with siRNA inhibited UFP-stimulated O(2)(-) production and mRNA expression of HO-1 and TF. Our findings suggest that JNK activation plays an important role in UFP-induced oxidative stress and stress response gene expression. PMID:19154785

Li, Rongsong; Ning, Zhi; Cui, Jeffery; Khalsa, Bhavraj; Ai, Lisong; Takabe, Wakako; Beebe, Tyler; Majumdar, Rohit; Sioutas, Constantinos; Hsiai, Tzung

2008-12-11

175

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

Microsoft Academic Search

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

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

176

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

177

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

178

Quinones and Aromatic Chemical Compounds in Particulate Matter Induce Mitochondrial Dysfunction: Implications for Ultrafine Particle Toxicity  

PubMed Central

Particulate pollutants cause adverse health effects through the generation of oxidative stress. A key question is whether these effects are mediated by the particles or their chemical compounds. In this article we show that aliphatic, aromatic, and polar organic compounds, fractionated from diesel exhaust particles (DEPs), exert differential toxic effects in RAW 264.7 cells. Cellular analyses showed that the quinone-enriched polar fraction was more potent than the polycyclic aromatic hydrocarbon (PAH)–enriched aromatic fraction in O2•? generation, decrease of membrane potential (??m), loss of mitochondrial membrane mass, and induction of apoptosis. A major effect of the polar fraction was to promote cyclosporin A (CsA)–sensitive permeability transition pore (PTP) opening in isolated liver mitochondria. This opening effect is dependent on a direct effect on the PTP at low doses as well as on an effect on ??m at high doses in calcium (Ca2+)-loaded mitochondria. The direct PTP effect was mimicked by redox-cycling DEP quinones. Although the aliphatic fraction failed to perturb mitochondrial function, the aromatic fraction increased the Ca2+ retention capacity at low doses and induced mitochondrial swelling and a decrease in ??m at high doses. This swelling effect was mostly CsA insensitive and could be reproduced by a mixture of PAHs present in DEPs. These chemical effects on isolated mitochondria could be reproduced by intact DEPs as well as ambient ultrafine particles (UFPs). In contrast, commercial polystyrene nanoparticles failed to exert mitochondrial effects. These results suggest that DEP and UFP effects on the PTP and ??m are mediated by adsorbed chemicals rather than the particles themselves.

Xia, Tian; Korge, Paavo; Weiss, James N.; Li, Ning; Venkatesen, M. Indira; Sioutas, Constantinos; Nel, Andre

2004-01-01

179

The Los Angeles International Airport as a source of ultrafine particles and other pollutants to nearby communities  

NASA Astrophysics Data System (ADS)

Air monitoring was performed in the vicinity of the Los Angeles International Airport (LAX) during the spring of 2003. The purpose of this monitoring was to determine the extent of airport emissions on downwind ambient air in a mixed use neighborhood that includes residences. A mobile air monitoring platform was developed and deployed to measure ultrafine particle numbers (UFP), size distributions, particle length, black carbon (BC), oxides of nitrogen (NO x), and particle-phase polycyclic aromatic hydrocarbons (PM-PAH). Pollutant levels were low at a coastal site upwind of the airport, with UFP ranging between 580 and 3800 counts cm -3, oxides of nitrogen (NO x) from 4 to 22 ppb, black carbon from 0.2 to 0.6 ?g m -3, and PM-PAH ranged from 18 to 36 ng m -3. Markedly higher UFP counts, with average counts of approximately 50,000 cm -3, were observed at a site 500 m downwind of the airport, which was strongly influenced by aircraft landings and where the community interfaced with airport facilities. Black carbon, PM-PAH, and NO x levels were elevated to a lesser extent at downwind locations. Transient peaks in UFP corresponding to aircraft landings and takeoffs were evident. A maximum UFP count reached 4.8 million particles cm -3 downwind of a runway used by jet aircraft for takeoffs. Particle size distributions differed substantially between upwind and downwind locations. The particle numbers at the upwind site were dominated by particles of approximately 90 nm diameter while downwind sites were dominated by particles peaking at approximately 10-15 nm. Additional data obtained from a study of UFP levels conducted subsequently by a co-author indicates that aircraft-generated UFP persist up to 900 m from an LAX runway [Biswas, S., Fine, P.M., Geller, M.D., Hering, S.V., Sioutas, C., 2005. Performance evaluation of a recently developed water-based condensation particle counter. Aerosol Science and Technology 39, 419-427]. Considered together, these observations suggest that airport operations are associated with elevated levels of UFP much further downwind in the neighboring community than would have been predicted by prior studies of UFP from roadway-traffic.

Westerdahl, Dane; Fruin, Scott A.; Fine, Phillip L.; Sioutas, Constantinos

180

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

181

The ultrafine particles over the southern mid-latitude Indian Ocean — wind-generated or advected down with subsidence?  

NASA Astrophysics Data System (ADS)

Concentration and number size distribution of aerosol particles from 4.4 to 168 nm diameter are measured at ten latitudinal positions in the Indian Ocean during the Pilot Expedition to Southern Ocean (PESO) from January 23 to March 31, 2004. Total number concentration of particles is minimum in the southern tropical trade wind region and maximum in the roaring forties. Number size distributions follow the power law over the northern Indian Ocean but are monomodal with the maxima lying between 35 and 60 nm over the southern Indian Ocean. Particles of diameter as small as 5 nm are observed in concentrations of ˜ 10 3 cm - 3 in the roaring forties (e.g. ˜ 40-50°S). Concentration of particles of < 50 nm diameter increases with wind speed. Thus, in addition to the ultrafine and Aitken mode particles being transported from the free troposphere to the marine boundary layer with the subsidence following cold frontal passages in the southern mid-latitudes, the wind-generated particles significantly contribute to the ultrafine aerosols down to 5 nm diameter in the roaring forties. Observations indicate that while the wind-generated particles dominate at ˜ 45°S, the particles associated with the subsidence dominate at ˜ 38°S.

Deshpande, C. G.; Pant, Vimlesh; Kamra, A. K.

2010-06-01

182

Production, growth and properties of ultrafine atmospheric aerosol particles in an urban environment  

NASA Astrophysics Data System (ADS)

Number concentrations of atmospheric aerosol particles were measured by a flow-switching type differential mobility particle sizer in an electrical mobility diameter range of 6-1000 nm in 30 channels near central Budapest with a time resolution of 10 min continuously from 3 November 2008 to 2 November 2009. Daily median number concentrations of particles varied from 3.8 × 103 to 29 ×103 cm-3 with a yearly median of 11.8 × 103 cm-3. Contribution of ultrafine particles to the total particle number ranged from 58 to 92% with a mean ratio and standard deviation of (79 ± 6)%. Typical diurnal variation of the particle number concentration was related to the major emission patterns in cities, new particle formation, sinks of particles and meteorology. Shapes of the monthly mean number size distributions were similar to each other. Overall mean for the number median mobility diameter of the Aitken and accumulation modes were 26 and 93 nm, respectively, which are substantially smaller than for rural or background environments. The Aitken and accumulation modes contributed similarly to the total particle number concentrations at the actual measurement location. New particle formation and growth unambiguously occurred on 83 days, which represent 27% of all relevant days. Hence, new particle formation and growth are not rare phenomena in Budapest. Their frequency showed an apparent seasonal variation with a minimum of 7.3% in winter and a maximum of 44% in spring. New particle formation events were linked to increased gas-phase H2SO4 concentrations. In the studied area, new particle formation is mainly affected by condensation sink and solar radiation. The formation process seems to be not sensitive to SO2, which was present in a yearly median concentration of 6.7 ?g m-3. This suggests that the precursor gas was always available in excess. Formation rate of particles with a diameter of 6 nm varied between 1.65 and 12.5 cm-3 s-1 with a mean and standard deviation of (4.2 ± 2.5) cm-3 s-1. Seasonal dependency for the formation rate could not be identified. Growth curves of nucleated particles were usually superimposed on the characteristic diurnal pattern of road traffic direct emissions. The growth rate of the nucleation mode with a median diameter of 6 nm varied from 2.0 to 13.3 nm h-1 with a mean and standard deviation of (7.7 ± 2.4) nm h-1. There was an indicative tendency for larger growth rates in summer and for smaller values in winter. New particle formation events increased the total number concentration by a mean factor and standard deviation of 2.3 ± 1.1 relative to the concentration that occurred immediately before the event. Several indirect evidences suggest that the new particle formation events occurred at least over the whole city, and were of regional type. The results and conclusions presented are the first information of this kind for the region over one-year long time period.

Salma, I.; Borsós, T.; Weidinger, T.; Aalto, P.; Hussein, T.; Dal Maso, M.; Kulmala, M.

2011-02-01

183

Exposure to ultrafine and fine particles and noise during cycling and driving in 11 Dutch cities  

NASA Astrophysics Data System (ADS)

Recent studies have suggested that exposures during traffic participation may be associated with adverse health effects. Traffic participation involves relatively short but high exposures. Potentially relevant exposures include ultrafine particles, fine particles (PM 2.5) and noise. Simultaneously, detailed real time exposure of particle number concentration (PNC), PM 2.5 and noise has been measured while driving and cycling 12 predefined routes of approximately 10-20 min duration. Sampling took place in eleven medium-sized Dutch cities on eleven weekdays in August till October 2006. To investigate variability in cyclists exposure, we systematically collected information on meteorology, GPS coordinates, type of road, traffic intensity, passing vehicles and mopeds while cycling. The overall mean PNC of car drivers was 5% higher than the mean PNC of cyclists. The overall mean concentration of PM 2.5 in the car was 11% higher than during cycling. Slightly higher 1-min peak concentrations were measured in the car (PNC 14%; PM 2.5 29% for 95-percentiles). Shorter duration peaks of PNC were higher during cycling (43% for 99-percentile of 1-s averages). Peaks in PNC typically last for less than 10 s. A large variability of exposure was found within and between routes. Factors that significantly predicted PNC variability during cycling were: passing vehicles (mopeds, cars), waiting for traffic lights, passing different types of (large) intersections and bicycle lanes and bike paths close to motorized traffic. No relation was found between PM 2.5 and those predictor variables. The correlation between PNC and noise was moderate (median 0.34). PM 2.5 had very low correlations with PNC and noise. PNC and PM 2.5 exposure of car drivers was slightly higher than that of cyclists. PNC was largely uncorrelated with PM 2.5 and reflected local traffic variables more than PM 2.5. Different factors were associated with high PNC and high noise exposures.

Boogaard, Hanna; Borgman, Frank; Kamminga, Jaap; Hoek, Gerard

184

Satellite-derived estimates of ultrafine particle concentrations over eastern North America  

NASA Astrophysics Data System (ADS)

High concentrations of ultrafine particles (UFP, i.e., particles with diameter < 100 nm) impact both human health and Earth's climate. Recent innovations in remote sensing technologies and data retrievals offer the potential for predicting UFP concentrations based on data from satellite-borne instrumentation. Herein we present a physically based statistical algorithm to estimate UFP concentrations across eastern North America using remotely sensed aerosol optical depth, Ångstrom exponent, ultraviolet solar radiation flux, and ammonia and sulfur dioxide concentrations. The proposed algorithm is built and independently evaluated using an array of in situ observations. The algorithm is able to capture up to 60% of the variability in daily measured UFP number concentrations at a regionally representative reference site and is thus applied to generate seasonal UFP concentration estimates across eastern North America. The resulting UFP concentrations are cross-evaluated with simulations from a global aerosol microphysics model. There is a negative bias in the model output relative to the satellite-driven proxy, which is largest (up to 76%) in summer and may be due to overestimation of UFP from the satellite-based algorithm derived herein, due to the higher availability of remote sensing data in clear-sky conditions or uncertainty in the model simulation of new particle formation. Nevertheless, the model and algorithm indicate similar spatial and seasonal variability (spatial correlation coefficients of 0.10 to 0.56), indicating the value of the satellite-based UFP proxy in global and regional model evaluation exercises and in efforts to identify regions where future in situ data collection should be prioritized.

Crippa, Paola; Spracklen, Dominick; Pryor, S. C.

2013-09-01

185

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

186

Levels of ultrafine particles in different microenvironments--implications to children exposure.  

PubMed

Indoor and outdoor ultrafine particles (UFPs) (0.01 to greater than 1 microm) concentration levels were examined in the area of Athens during cold period of 2003 and 2004. Seven primary schools, located in areas with different characteristics of urbanization and traffic density, as well as a typical suburban residence, were monitored. Moreover, in-vehicle concentration levels, while driving along major avenues and in the heavy-trafficked centre of Athens, were measured (mean route duration: 45 min). UFPs number concentration was monitored by condensation particle counter (model CPC 3007), with a logging time interval of 1 min. The highest mean indoor concentrations were observed in a small carpet-covered library and a teachers' office (8-hour mean equal to 52.6x10(3) particles/cm(3) and 50.2x10(3) particles/cm(3), respectively), at the same school unit. The highest outdoor concentrations (8-hour mean equal to 36.9x10(3) particles/cm(3) and 38.8x10(3) particles/cm(3)) were measured at two schools, both affected by heavy traffic. Finally, the highest in-vehicle concentrations (148.0x10(3)-173.0x10(3) particles/cm(3)) were measured in central commercial areas of Athens during, on average, 55 min drives. Indoor-to-outdoor concentration (I/O) ratios were below 1.00 at all sites. The largest ratio (0.88) was observed in the residence, during a day when there was cleaning activity in the room monitored. Outdoor concentrations diurnal cycles, both outside the schools and the residence, were closely related to traffic. Indoor concentrations inside schools were relatively stable in classrooms. Nevertheless, number concentrations exhibited variability when there were significant changes in room occupancy. Diurnal variation of indoor concentrations at the residence followed the respective outdoor one with a delay of 1 h or less, in the absence of strong indoor sources, indicating the major contribution of outdoor UFPs to the indoor concentration levels. The present work is the first effort to examine UFPs indoor and outdoor concentration levels in the area of Athens. The obtained concentration data give an insight on the concentration levels to which children may be exposed. They may be also very useful in epidemiological studies, in order to estimate children total personal exposure though the calculation of exposures received in different microenvironments. This kind of studies may contribute to the design of effective policies and mitigation measures for the protection of public health. PMID:17888492

Diapouli, E; Chaloulakou, A; Spyrellis, N

2007-09-20

187

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

188

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

189

Biological effects of ultrafine model particles in human macrophages and epithelial cells in mono- and co-culture.  

PubMed

Exposure to elevated concentrations of ambient ultrafine particulate matter has been associated with increased morbidity and mortality in the public. The particle parameters triggering the underlying mechanisms are largely unknown. The aim of this study was to compare biological in vitro-effects of ultrafine model particles (hematite, silicasol) of different composition and different sizes to evaluate the influence of these parameters. Human epithelial (A549) and macrophage (THP-1, Mono Mac 6) cell lines in mono-culture as well as in co-culture were used as cellular models. The uptake of hematite particles into A549 cells was identified by light microscopy and confirmed by transmission electron microscopy. The loss of membrane integrity measured by the lactate dehydrogenase assay as well as the induction of interleukin-6 and interleukin-8 release were affected by the particles in a dose dependent manner. This study demonstrated that particle size and particle composition, respectively, were responsible for the observed biological effects. Furthermore, the co-cultures of epithelial cells (A549) and macrophages (Mono Mac 6 or differentiated THP-1) showed an increased sensitivity to particles concerning the cytokine release in comparison to the mono-cultures of each cell type. PMID:15471099

Wottrich, Ralf; Diabaté, Silvia; Krug, Harald F

2004-09-01

190

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

191

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

Microsoft Academic Search

Ultrafine aluminum-substituted strontium hexaferrite particles have been prepared via citrate sol-gel route. Gels were synthesized with molar ratios [Al3+]:[Fe3+] 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 24h. Electron energy dispersive X-ray spectroscopy (EDX) verified the presence of Al in the substituted samples. X-ray diffraction (XRD)

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

192

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

2013-04-06

193

Continuous monitoring of ultrafine, fine, and coarse particles in a residence for 18 months in 1999-2000.  

PubMed

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 indoor air concentrations of size-resolved particles (0.01-20 microm) caused by (1) diumal and seasonal variation of outdoor air concentrations and meteorological variables, (2) indoor sources such as cooking and using candles, and (3) activities affecting air change rates such as opening windows and using fans. A second objective was to test and compare available instruments for their suitability in providing real-time estimates of particle levels and ancillary variables. Despite different measuring principles, the instruments employed in this study agreed reasonably well for particles less than 10 microm in diameter. The three instruments measuring fine and coarse particles (aerodynamic diameter between 0.3 and 20 microm) agreed to within 30% in their overall estimates of total volume. Two of these instruments employed optical scattering, and the third used an aerodynamic acceleration principle. However, several lines of evidence indicated that the instrument employing aerodynamic acceleration overestimated concentrations for particle diameters greater than 10 microm. A fourth instrument measuring ultrafine and accumulation-mode particles (0.01-1 microm) was operated with two different inlets providing somewhat different particle size ranges. The two inlets agreed in the ultrafine region (< 0.1 microm) but diverged increasingly for larger particles (up to 0.445 microm). Indoor sources affecting ultrafine particle concentrations were observed 22% of the time, and sources affecting fine and coarse particle concentrations were observed 12 and 15% of the time, respectively. When an indoor source was operating, particle concentrations for different sizes ranged from 2 to 20 times the average concentrations when no indoor source was apparent. Indoor sources, such as cooking with natural gas, and simple physical activities, such as walking, accounted for a majority (50-90%) of the ultrafine and coarse particle concentrations, whereas outdoor sources were more important for accumulation-mode particles between 0.1 and 1 microm in diameter. Averaged for the entire year and including no periods when indoor sources were apparent, the number distribution was bimodal, with a peak at approximately 10 nm (possibly smaller), a shallow minimum at approximately 14 nm, and a second broad peak at approximately 68 nm. The volume distribution was also bimodal, with a broad peak at approximately 200 nm, a minimum at approximately 1.2 microm, and then an upward slope again through the remaining size fractions. A database was created on a 5-min averaging time basis. It contains more than 90,000 measurements by two of the instruments and approximately 30,000 by the two optical scattering instruments. About 4500 hour-long average air change rates were also calculated throughout the year using a dedicated gas chromatograph with electron capture detection (GC/ECD). At high air change rates [> 0.8 air changes per hour (hr(-1))], particle concentrations were either elevated (when no source was present) or depressed (when an indoor source was operating) by factors of up to 2 compared with low air change rates. PMID:12139348

Wallace, Lance; Howard-Reed, Cynthia

2002-07-01

194

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

195

Measurements and predictors of on-road ultrafine particle concentrations and associated pollutants in Los Angeles  

NASA Astrophysics Data System (ADS)

Motor vehicles are the dominant source of oxides of nitrogen (NO x), particulate matter (PM), and certain air toxics (e.g., benzene, 1,3-butadiene) in urban areas. On roadways, motor vehicle-related pollutant concentrations are typically many times higher than ambient concentrations. Due to high air exchange rates typical of moving vehicles, this makes time spent in vehicles on roadways a major source of exposure. This paper presents on-road measurements for Los Angeles freeways and arterial roads taken from a zero-emission electric vehicle outfitted with real-time instruments. The objective was to characterize air pollutant concentrations on roadways and identify the factors associated with the highest concentrations. Our analysis demonstrated that on freeways, concentrations of ultrafine particles (UFPs), black carbon, nitric oxide, and PM-bound polycyclic aromatic hydrocarbons (PM-PAH) are generated primarily by diesel-powered vehicles, despite the relatively low fraction (˜6%) of diesel-powered vehicles on Los Angeles freeways. However, UFP concentrations on arterial roads appeared to be driven primarily by proximity to gasoline-powered vehicles undergoing hard accelerations. Concentrations were roughly one-third of those on freeways. By using a multiple regression model for the freeway measurements, we were able to explain 60-70% of the variability in concentrations of UFP, black carbon, nitric oxide, and PM-PAH using measures of diesel truck density and hour of day (as an indicator of wind speed). Freeway concentrations of these pollutants were also well correlated with readily available annual average daily truck counts, potentially allowing improved population exposure estimates for epidemiology studies. Based on these roadway measurements and average driving time, it appears that 33-45% of total UFP exposure for Los Angeles residents occurs due to time spent traveling in vehicles.

Fruin, S.; Westerdahl, D.; Sax, T.; Sioutas, C.; Fine, P. M.

196

Concentration response functions for ultrafine particles and all-cause mortality and hospital admissions: results of a European expert panel elicitation.  

PubMed

Toxicological studies have provided evidence of the toxicity of ultrafine particles (UFP), but epidemiological evidence for health effects of ultrafines is limited. No quantitative summary currently exists of concentration-response functions for ultrafine particles that can be used in health impact assessment. The goal was to specify concentration-response functions for ultrafine particles in urban air including their uncertainty through an expert panel elicitation. Eleven European experts from the disciplines of epidemiology, toxicology, and clinical medicine selected using a systematic peer-nomination procedure participated. Using individual ratings supplemented with group discussion, probability distributions of effect estimates were obtained for all-cause mortality and cardiovascular and respiratory hospital admissions. Experts judged the small database of epidemiological studies supplemented with experimental studies sufficient to quantify effects of UFP on all-cause mortality and to a lesser extent hospital admissions. Substantial differences in the estimated UFP health effect and its uncertainty were found between experts. The lack of studies on long-term exposure to UFP was rated as the most important source of uncertainty. Effects on hospital admissions were considered more uncertain. This expert elicitation provides the first quantitative evaluation of estimates of concentration response functions between urban air ultrafine particles and all-cause mortality and hospital admissions. PMID:19958027

Hoek, Gerard; Boogaard, Hanna; Knol, Anne; de Hartog, Jeroen; Slottje, Pauline; Ayres, Jon G; Borm, Paul; Brunekreef, Bert; Donaldson, Ken; Forastiere, Francesco; Holgate, Stephen; Kreyling, Wolfgang G; Nemery, Benoit; Pekkanen, Juha; Stone, Vicki; Wichmann, H-Erich; van der Sluijs, Jeroen

2010-01-01

197

Densification, Microstructure Evolution and Mechanical Properties of Ultrafine SiC Particle-Dispersed ZrB 2 Matrix Composites  

Microsoft Academic Search

\\u000a The densification behavior along with the microstructure evolution and some mechanical properties of four ultrafine SiC particle-dispersed\\u000a 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\\u000a under a maximum uniaxial pressure of 45 MPa. The presence of SiC

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

2011-01-01

198

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...

199

Activation of endothelial cells after exposure to ambient ultrafine particles: The role of NADPH oxidase  

SciTech Connect

Several studies have shown that ultrafine particles (UFPs) may pass from the lungs to the circulation because of their very small diameter, and induce lung oxidative stress with a resultant increase in lung epithelial permeability. The direct effects of UFPs on vascular endothelium remain unknown. We hypothesized that exposure to UFPs leads to endothelial cell O{sub 2}{sup {center_dot}}{sup -} generation via NADPH oxidase and results in activation of endothelial cells. Our results showed that UFPs, at a non-toxic dose, induced reactive oxygen species (ROS) generation in mouse pulmonary microvascular endothelial cells (MPMVEC) that was inhibited by pre-treatment with the ROS scavengers or inhibitors, but not with the mitochondrial inhibitor, rotenone. UFP-induced ROS generation in MPMVEC was abolished by p67{sup phox} siRNA transfection and UFPs did not cause ROS generation in MPMVEC isolated from gp91{sup phox} knock-out mice. UFP-induced ROS generation in endothelial cells was also determined in vivo by using a perfused lung model with imaging. Moreover, Western blot and immunofluorescence staining results showed that MPMVEC treated with UFPs resulted in the translocation of cytosolic proteins of NADPH oxidase, p47{sup phox}, p67{sup phox} and rac 1, to the plasma membrane. These results demonstrate that NADPH oxidase in the pulmonary endothelium is involved in ROS generation following exposure to UFPs. To investigate the activation of endothelial cells by UFP-induced oxidative stress, we determined the activation of the mitogen-activated protein kinases (MAPKs) in MPMVEC. Our results showed that exposure of MPMVEC to UFPs caused increased phosphorylation of p38 and ERK1/2 MAPKs that was blocked by pre-treatment with DPI or p67{sup phox} siRNA. Exposure of MPMVEC obtained from gp91{sup phox} knock-out mice to UFPs did not cause increased phosphorylation of p38 and ERK1/2 MAPKs. These findings confirm that UFPs can cause endothelial cells to generate ROS directly via activation of NADPH oxidase. UFP-induced ROS lead to activation of MAPKs through induced phosphorylation of p38 and ERK1/2 MAPKs that may further result in endothelial dysfunction through production of cytokines such as IL-6. Our results suggest that endothelial oxidative stress may be an important mechanism for PM-induced cardiovascular effects.

Mo Yiqun; Wan Rong [Department of Environmental Health and Occupational Health Sciences, School of Public Health and Information Sciences, University of Louisville, 485 E. Gray Street, Louisville, KY 40209 (United States); Chien Sufan [Department of Surgery, University of Louisville, Louisville, KY (United States); Tollerud, David J. [Department of Environmental Health and Occupational Health Sciences, School of Public Health and Information Sciences, University of Louisville, 485 E. Gray Street, Louisville, KY 40209 (United States); Zhang Qunwei [Department of Environmental Health and Occupational Health Sciences, School of Public Health and Information Sciences, University of Louisville, 485 E. Gray Street, Louisville, KY 40209 (United States)], E-mail: Qunwei.Zhang@louisville.edu

2009-04-15

200

Water-soluble ions in nano/ultrafine/fine/coarse particles collected near a busy road and at a rural site.  

PubMed

This study investigated water-soluble ions in the sized particles (particularly nano (PM(0.01-0.056))/ultrafine (PM(0.01-0.1))) collected using MOUDI and Nano-MOUDI samplers near a busy road site and at a rural site. The analytical results demonstrate that nano and coarse particles exhibited the highest (16.3%) and lowest (8.37%) nitrate mass ratios, respectively. The mass ratio of NO(3)(-) was higher than that of SO(4)(2-) in all the sized particles at the traffic site. The secondary aerosols all displayed trimodal distributions. The aerosols in ultrafine particles collected at the roadside site exhibited Aitken mode distributions indicating they were of local origin. This finding was not observed for those ultrafine particles collected at the rural site. The mass median diameters (MMDs) of the nano, ultrafine, and fine particles were smaller at the traffic site than at the rural site, possibly related to the contribution of mobile engine emissions. PMID:16772108

Lin, Chih-Chung; Chen, Shui-Jen; Huang, Kuo-Lin; Lee, Wen-Jhy; Lin, Wen-Yinn; Liao, Chiu-Jung; Chaung, Hso-Chi; Chiu, Chuen-Huey

2006-06-12

201

Vertical and horizontal concentration distributions of ultrafine particles near a highway  

NASA Astrophysics Data System (ADS)

Assessment of human health effects associated with particles requires knowledge of their emission factors and dispersion characteristics. A field experiment was recently conducted to determine the vertical and horizontal dispersion of particles emitted from highway vehicles. The measurements were conducted near the highway I-90 in Liverpool (NY) over a flat terrain, where the predominant dispersion mechanisms were atmospheric turbulence and traffic-produced turbulence (TPT). Real-time vertical number concentration measurements were made using several identical water condensation particle counters (WCPCs) over nine heights up to 10 m. Three sites (at distances of 15, 50, and 100 m from the highway) were selected to study the concentration profiles. As previously observed at other sites, particle concentrations decay with increasing distance from highways. At the site closest to the highway, the highest concentration was observed under a downwind condition with the average wind speed ˜1 ms -1. Under conditions of low wind speed, particles from the highway are observed even at locations upwind of the highway. The vertical profiles of particle concentrations at different measurement locations varied with wind speed, wind direction and distance to the highway. The correlation coefficients of particle concentrations at different elevations reveal the characteristics of the plume dispersion and its development in the horizontal and vertical directions. The experimental results suggest the need for three-dimensional modeling of particle plumes from highways and the importance of considering TPT for accurate prediction of particle dispersion near roadways.

He, Meilu; Dhaniyala, Suresh

2012-01-01

202

Filter Performance of N99 and N95 Facepiece Respirators Against Viruses and Ultrafine Particles  

Microsoft Academic Search

The performance of three filtering facepiece respirators (two models of N99 and one N95) chal- lenged with an inert aerosol (NaCl) and threevirus aerosols (enterobacteriophages MS2 and T4 and Bacillus subtilis phage)—all with significant ultrafine components—was examined using a manikin-based protocol with respirators sealed on manikins. Three inhalation flow rates, 30, 85, and 150 l min21, were tested. The filter

ROBERT M. ENINGER; TAKESHI HONDA; ATIN ADHIKARI; HELVI HEINONEN-TANSKI; TIINA REPONEN; SERGEY A. GRINSHPUN

2008-01-01

203

Cyto- and genotoxicity of ultrafine TiO 2 particles in cultured human lymphoblastoid cells  

Microsoft Academic Search

Titanium dioxide is frequently used in the production of paints, paper, plastics, welding rod-coating material, and cosmetics, because of its low toxicity. However, recent studies have shown that nano-sized or ultrafine TiO2 (UF-TiO2) (<100nm in diameter) can generate pulmonary fibrosis and lung tumor in rats. Cytotoxicity induced by UF-TiO2 in rat lung alveolar macrophages was also observed. This generates great

Jing J. Wang; Barbara J. S. Sanderson; He Wang

2007-01-01

204

Effect of particle size on the flocculation behaviour of ultra-fine clays in salt solutions  

Microsoft Academic Search

The Athabasca oil sands deposit in Alberta contains ~5 x 109 m 3 of bitumen accessible by surface mining. During bitumen separation from the mined ore, ultra-fine (<300 rim) aluminosilicate clays only a few layers thick (U\\/F) are mobilized and become dispersed in the process water. In this water containing dissolved salts from natural deposits, U\\/F are capable of forming

L. S. Kotlyar; B. D. Sparks; Y. Lepage; J. R. Woods

1998-01-01

205

Daily Mortality and Fine and Ultrafine Particles in Erfurt, Germany. Part I: Role of Particle Number and Particle Mass.  

National Technical Information Service (NTIS)

Epidemiologic studies have shown an association between airborne particles and mortality data, but uncertainty persists as to which aspects of the particle mixture are the driving force underlying observed associations. Further, only a small number of stu...

H. E. Wichmann C. Spix T. Tuch G. Wolke A. Peters J. Heinrich W. G. Kreyling J. Heyder

2000-01-01

206

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

207

Association of Biomarkers of Systemic Inflammation with Organic Components and Source Tracers in Quasi-Ultrafine Particles  

PubMed Central

Background Evidence is needed regarding the air pollutant components and their sources responsible for associations between particle mass concentrations and human cardiovascular outcomes. We previously found associations between circulating biomarkers of inflammation and mass concentrations of quasi-ultrafine particles ? 0.25 ?m in aerodynamic diameter (PM0.25) in a panel cohort study of 60 elderly subjects with coronary artery disease living in the Los Angeles Basin. Objectives We reassessed biomarker associations with PM0.25 using new particle composition data. Methods Weekly biomarkers of inflammation were plasma interleukin-6 (IL-6) and soluble tumor necrosis factor-? receptor II (sTNF-RII) (n = 578). Exposures included indoor and outdoor community organic PM0.25 constituents [polycyclic aromatic hydrocarbons (PAHs), hopanes, n-alkanes, organic acids, water-soluble organic carbon, and transition metals]. We analyzed the relation between biomarkers and exposures with mixed-effects models adjusted for potential confounders. Results Indoor and outdoor PAHs (low-, medium-, and high-molecular-weight PAHs), followed by hopanes (vehicle emissions tracer), were positively associated with biomarkers, but other organic components and transition metals were not. sTNF-RII increased by 135 pg/mL [95% confidence interval (CI), 45–225 pg/mL], and IL-6 increased by 0.27 pg/mL (95% CI, 0.10–0.44 pg/mL) per interquartile range increase of 0.56 ng/m3 outdoor total PAHs. Two-pollutant models of PM0.25 with PAHs showed that nominal associations of IL-6 and sTNF-RII with PM0.25 mass were completely confounded by PAHs. Vehicular emission sources estimated from chemical mass balance models were strongly correlated with PAHs (R = 0.71). Conclusions Traffic emission sources of organic chemicals represented by PAHs are associated with increased systemic inflammation and explain associations with quasi-ultrafine particle mass.

Delfino, Ralph J.; Staimer, Norbert; Tjoa, Thomas; Arhami, Mohammad; Polidori, Andrea; Gillen, Daniel L.; Kleinman, Michael T.; Schauer, James J.; Sioutas, Constantinos

2010-01-01

208

Preparation of a Langmuir-Blodgett layer of ultrafine platinum particles and its application to n-Si for efficient photoelectrochemical solar cells  

SciTech Connect

A Langmuir layer of ultrafine platinum particles (2--6 nm in diam) has been developed on a water surface by dropping a Pt colloid solution, prepared by refluxing an ethanol-water (1:1) solution of hexachloroplatinic(IV) acid in the presence of poly(N-vinyl-2-pyrrolidone) as a stabilizer. The layer is transferred onto a single-crystal n-type silicon (n-Si) wafer by the horizontal lifting method. The Pt particles are rather homogeneously scattered on n-Si, and the particle density can be controlled on a nanometer scale by changing the area of the Langmuir layer at the time of transfer. The open-circuit photovoltage (V[sub oc]) for photoelectrochemical (PEC) solar cells with such n-Si electrodes is inversely related to Pt-particle density, and reaches 0.635 V, much higher than that for n-Si coated with a continuous Pt layer (ca. 0.30 V) or that for the conventional p-n junction Si solid solar cell of a similar simple cell structure (ca. 0.59 V). This result is in harmony with the previously proposed theory, the above increase in V[sub oc] being explained by the decrease in the majority carrier dark saturation current density.

Yae, Shinji; Nakanishi, Isao; Nakato, Yoshihiro; Mori, Hirotaro (Osaka Univ. (Japan)); Toshima, Naoki (Univ. of Tokyo (Japan). Dept. of Industrial Chemistry)

1994-11-01

209

a Flow Chamber for Quantitative Nucleation Investigations and Ultrafine Particle Production and Capture  

Microsoft Academic Search

A flow diffusion nucleation chamber to be used for homogeneous nucleation studies and particle production and capture was designed, characterized, constructed, and tested. A mathematical model was developed to predict the temperature, concentration, supersaturation, and nucleation rate profiles throughout the nucleation chamber. Fluid dynamic modeling was used to better understand the flow characteristics in the chamber. Critical supersaturation versus temperature

Vivek Vohra

1996-01-01

210

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

211

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

212

An electrical sensor for long-term monitoring of ultrafine particles in workplaces  

NASA Astrophysics Data System (ADS)

Pegasor Oy Ltd. (Finland) has developed a diffusion charging measurement device that enables continuous monitoring of fine particle concentration at a low initial and lifecycle cost. The innovation, for which an international process and apparatus patent has been applied for, opens doors for monitoring nanoparticle concentrations in workplaces. The Pegasor Particle Sensor (PPS) operates by electrostatically charging particles passing through the sensor and then measuring the current caused by the charged particles as they leave the sensor. The particles never touch the sensor and so never accumulate on its surfaces or need to be cleaned off. The sensor uses an ejector pump to draw a constant sample flow into the sensing area where it is mixed with the clean, charged pump flow air (provided by an external source). The sample flow containing charged particles passes through the sensor. The current generated by the charge leaving the detection volume is measured and related to the particle surface area. This system is extremely simple and reliable - no contact, no moving parts, and all critical parts of the sensor are constantly cleaned by a stream of fresh, filtered air. Due to the ejector pump, the sample flow, and respectively the sensor response is independent of the flow and pressure conditions around the sampling inlet. Tests with the Pegasor Particle Sensor have been conducted in a laboratory, and at a workplace producing nanoparticles for glass coatings. A new measurement protocol has been designed to ensure that process workers are not exposed to unusually high nanoparticle concentrations at any time during their working day. One sensor is placed inside the process line, and a light alarm system indicates the worker not to open any protective shielding or ventilation systems before concentration inside has reached background levels. The benefits of PPS in industrial hygiene are that the same monitoring technology can be used at the source as well as at the worker breathing zone. Up to eight sensors can be installed in series for centralized monitoring of the whole process in real time.

Lanki, Timo; Tikkanen, Juha; Janka, Kauko; Taimisto, Pekka; Lehtimäki, Matti

2011-07-01

213

Carbonaceous and ionic components in ultrafine and fine particles at four sampling sites in the vicinity of roadway intersection  

NASA Astrophysics Data System (ADS)

Ultrafine particles (UFPs; Dp < 0.1 ?m) and fine particles (FPs; Dp < 2.5 ?m) were simultaneously collected for 11 h periods in the daytime and in the nighttime at four sites (S1-S4) around a roadway intersection in an urban area. Sampling was carried out for 14 consecutive days to determine the effect of the intersection on the chemical composition of atmospheric UFPs and FPs. The relative contributions of organic carbon (OC) and elemental carbon (EC) to total carbon (TC) in the daytime samples were 65-86% (UFPs: 83-86%; FPs: 65-75%) and 14-35% (UFPs: 14-17%; FPs: 25-35%), respectively, whereas those in the nighttime samples accounted for 71-90% (UFPs: 87-90%; FPs: 71-78%) and 10-29% (UFPs: 10-13%, FPs: 22-29%), respectively, indicating that the contribution of EC in both UFPs and FPs was higher during the daytime. The decrease in the concentration of carbonaceous components with distance from the intersection indicated a strong effect of motor vehicles emissions on the composition of UFPs and FPs around the intersection. The diurnal variations of sulfate and nitrate in UFPs are consistent with the seasonal variations of sulfate and nitrate in FPs showing higher sulfate and nitrate concentrations in summer and winter, respectively. Not observed in FPs, the diurnal patterns of sulfate and nitrate in UFPs may be closely related to particle size in comparison with larger particles, because smaller particles are more strongly affected by the surrounding environment, for example, through oxidation and dissociation. The present study provides interesting observation that the emission characteristics of OC and EC fractions can be different in the same roadside environment depending on the distance from roadway intersection and particle sizes. Furthermore, concentration difference between EC and black carbon (BC) was found at specific site indicating different EC emission characteristics at the same roadside environment.

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

2013-08-01

214

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

215

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

216

Influence of ozone concentration and temperature on ultra-fine particle and gaseous volatile organic compound formations generated during the ozone-initiated reactions with emitted terpenes from a car air freshener  

Microsoft Academic Search

Experiments were conducted to identify the emissions from the car air freshener and to identify the formation of ultra-fine particles and secondary gaseous compounds during the ozone-initiated oxidations with emitted volatile organic compounds (VOCs). The identified primary constituents emitted from the car air freshener in this study were ?-pinene, ?-pinene, p-cymene, and limonene. Formation of ultra-fine particles (4.4–160nm) was observed

Rheo B. Lamorena; Woojin Lee

2008-01-01

217

Modification of laminar flow ultrafine condensation particle counters for the enhanced detection of 1 nm condensation nuclei  

SciTech Connect

This paper describes simple modifications to thermally diffusive laminar flow ultrafine condensation particle counters (UCPCs) that allow detection of {approx}1 nm condensation nuclei with much higher efficiencies than have been previously reported. These nondestructive 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 UCPCs (BNL 3025A and BNL DEGUCPC) were measured with high resolution mobility classified aerosols composed of NaCl, W, molecular ion standards of tetraalkyl ammonium bromide, and neutralizer-generated ions. With negatively charged NaCl aerosol, the BNL 3025A and BNL DEGUCPC achieved detection efficiencies of 37% (90x increase over TSI 3025A) at 1.68 nm mobility diameter (1.39 nm geometric diameter) and 23% (8x increase over UMN DEG-UCPC) at 1.19 nm mobility diameter (0.89 nm geometric diameter), respectively. Operating conditions for both UCPCs were identified that allowed negatively charged NaCl and W particles, but not negative ions of exactly the same mobility size, to be efficiently detected. This serendipitous material dependence, which is not fundamentally understood, suggests that vapor condensation might sometimes allow for the discrimination between air 'ions' and charged 'particles.' As a detector in a scanning mobility particle spectrometer (SMPS), a UCPC with this strong material dependence would allow for more accurate measurements of sub-2 nm aerosol size distributions due to the reduced interference from neutralizer-generated ions and atmospheric ions, and provide increased sensitivity for the determination of nucleation rates and initial particle growth rates.

Kuang, C.; Chen, M.; McMurry, P. H.; Wang, J.

2011-10-01

218

Fine and ultrafine particles in the Zürich (Switzerland) area measured with a mobile laboratory: an assessment of the seasonal and regional variation throughout a year  

NASA Astrophysics Data System (ADS)

On occasion of the project YOGAM (year of gas phase and aerosol measurements), the spatial and temporal variation of selected aerosol and gas phase parameters was assessed for the Zürich (Switzerland) area with a new mobile pollutant measurement laboratory. This assessment based on on-road measurements along a specified route on selected days during different seasons in 2001/2002, covering urban, suburban and rural regions. Special focus was put on the investigation and characterization of particles in the fine (particle diameter D<2.5 mm) and ultrafine (D<100 nm) size ranges. Analysis of Variance (ANOVA) showed that the variance of all considered fine and ultrafine aerosol parameters (i.e. particle background and total number concentration for particles larger than 3 nm, number concentrations in the size ranges 7-30 nm and 80-140 nm, as well as the active surface area concentration) was significantly larger for day-to-day than for spatial variation. However, Principal Component Analysis (PCA) found a similar regional pollution pattern within every single measuring day. Lowest particle background levels (D>3 nm) were found in rural areas at higher elevation (15 000 cm-3), while corresponding mean background values for urban and freeway-influenced areas were typically 35 000 cm-3 and >80 000 cm-3, respectively. Meteorology, i.e. prevailing weather conditions not only governed the day-to-day concentration variations in the selected area, but also influenced the formation of primary (directly traffic-related) and in few cases secondary (biogenic or anthropogenic) ultrafine particles. Overall, low temperatures regularly enhanced primary ultrafine particle formation in urban areas. There was a possible indication for relatively low number concentrations of secondary ultrafine particles during a few warm and sunny spring days. Mobile measurements as they were performed in this study have been shown to be suitable for pollutant assessments to obtain good information on spatial and day-to-day variability. For experimental studies concerning spatial resolution on a relatively short time scale (<1 day), a mobile measurement design may even be more appropriate than a network of stationary measuring sites.

Bukowiecki, N.; Dommen, J.; Prévôt, A. S. H.; Weingartner, E.; Baltensperger, U.

2003-09-01

219

Hsp70 expression and free radical release after exposure to non-thermal radio-frequency electromagnetic fields and ultrafine particles in human Mono Mac 6 cells  

Microsoft Academic Search

The contemporary urban environment has become increasingly complex in its composition, leading to discussions regarding possible novel health effects. Two factors that recently have received considerable attention are ultrafine particles (UFP; <0.1?m) produced by combustion processes and emissions from wireless communication devices like mobile phones that emit in the radio-frequency (RF) part of the spectrum. Several studies have shown biological

M. Simkó; C. Hartwig; M. Lantow; M. Lupke; M.-O. Mattsson; Q. Rahman; J. Rollwitz

2006-01-01

220

Fine and ultrafine particles in the Zürich (Switzerland) area measured with a mobile laboratory. An assessment of the seasonal and regional variation throughout a year  

NASA Astrophysics Data System (ADS)

On occasion of the project YOGAM (year of gas phase and aerosol measurements), the spatial and temporal variation of selected aerosol and gas phase parameters was assessed for the Zürich (Switzerland) area with a new mobile pollutant measurement laboratory. This assessment based on on-road measurements along a specified route on selected days during different seasons in 2001/2002, covering urban, suburban and rural regions. Special focus was put on the investigation and characterization of particles in the fine (<2.5 mm) and ultrafine (<100 nm) size ranges. Analysis of Variance (ANOVA) showed that the variance of all considered fine and ultrafine aerosol parameters (i.e. particle background and total number concentration for particles larger than 3 nm, number concentrations in the size ranges 7-30 nm and 80-140 nm, as well as the active surface area concentration) was considerably larger for day-to-day than for spatial variation. However, Principal Component Analysis (PCA) found a similar regional pollution pattern within every single measuring day. Lowest particle background levels were found in rural areas at higher elevation 15 000 cm-3), while corresponding mean background values for urban and freeway-influenced areas were typically 35 000 cm-3 and >80 000 cm-3, respectively. Meteorology, i.e. prevailing weather conditions not only governed the day-to-day concentration variations in the selected area, but also influenced the formation of both primary (directly traffic-related) and secondary (biogenic or indirectly traffic-related) ultrafine particles. Overall, low temperatures regularly enhanced primary ultrafine particle formation in urban areas. There was however indication for relatively low number concentrations of secondary ultrafine particles during only a few warm and sunny spring days. Mobile measurements as described in this study have been shown to be suitable for long-term pollutant assessments, to obtain good information on spatial variability and reasonable information on the temporal variability. For aspects concerning spatial resolution, an experimental design using a mobile measurement may even be more appropriate than a network of stationary measuring sites.

Bukowiecki, N.; Dommen, J.; Prévát, A. S. H.; Weingartner, E.; Baltensperger, U.

2003-05-01

221

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

222

Cloud condensation nuclei droplet growth kinetics of ultrafine particles during anthropogenic nucleation events  

NASA Astrophysics Data System (ADS)

Evolution of the cloud condensation nucleus (CCN) activity of 36 ± 4 nm diameter anthropogenic aerosol particles at a water supersaturation of 1.0 ± 0.1% is examined for particle nucleation and growth. During the early stages of one event, relatively few of the anthropogenic particles at 36 nm were CCN active and their growth rates by water condensation were delayed relative to ammonium sulphate particles. As the event progressed, the particle size distribution evolved to larger sizes and the relative numbers of particles at 36 nm that were CCN active increased until all the 36 nm particles were activating at the end of the event. Based on the chemistry of larger particles and the results from an aerosol chemical microphysics box model, the increase in CCN activity of the particles was most likely the result of the condensation of sulphate in this case. Despite the increased CCN activity, a delay was observed in the initial growth of these particles into cloud droplets, which persisted even when the aerosol was most CCN active later in the afternoon. Simulations show that the delay in water uptake is explained by a reduction of the mass accommodation coefficient assuming that the composition of the 36 nm particles is the same as the measured composition of the 60-100 nm particles.

Shantz, N. C.; Pierce, J. R.; Chang, R. Y.-W.; Vlasenko, A.; Riipinen, I.; Sjostedt, S.; Slowik, J. G.; Wiebe, A.; Liggio, J.; Abbatt, J. P. D.; Leaitch, W. R.

2012-02-01

223

Dynamic variations of ultrafine, fine and coarse particles at the Lu-Lin background site in East Asia  

NASA Astrophysics Data System (ADS)

The characteristics of atmospheric ultrafine particles (i.e. <100 nm, nanoparticles or PM0.1), PM2.5 and PM10 were studied at the Lulin Atmospheric Background Station (LABS, 2862 m a.s.l., Taiwan) as part of the 7SEAS/Dongsha campaign. Sampling was conducted in July and August of 2009 and September to November of 2010, during which two 96-h and four 72-h PM samples were taken. Real-time particle size distributions were measured continuously from July to August of 2009 and July to November of 2010. PM0.1, PM2.5 and PM10 were collected by using two MOUDIs (micro-orifice uniform deposit impactor, MSP 110) and a Dichotomous PM10 sampler (Andersen SA-241) while real-time size distributions of particles of 5.5–350 nm in diameter were measured by an SMPS (scanning mobility particle sizer, TSI 3936). Filter samples were analyzed for gravimetric mass and chemical compositions, including organic carbon (OC), element carbon (EC), water-soluble ions and trace elements. Meteorology parameters and gaseous O3 and CO concentrations were also monitored along with the SMPS data for studying particle nucleation, condensation, SOA (secondary organic aerosol) formation and long-range air pollutant transport at the LABS. SMPS data showed that nanoparticle concentrations at the LABS remained relatively stable at low level (˜300–500 #/cm3) during the nighttime (22:00–04:00), increased during daytime, and reached a maximum (˜2000–4000 #/cm3) in the afternoon (12:00–16:00). The NMD (number median diameter) showed an opposite trend with the peak number concentrations observed in the afternoon corresponding to the smallest NMD (20–40 nm). These results indicate the dominance of local sources rather than the transport from other atmospheric air because that the lifetime of nanoparticles was only few minutes. Chemical analysis of filter samples showed that the concentrations of trace elements K and Mn, which serve as biomass burning markers, were elevated in the fine particle fractions during November 9–12th when the air mass passed through South and Southeast Asia prior to reaching the LABS. The concentrations of K and Mn would have been low if the aerosols had local origins The biomass burning derived K was found in all fine particle samples at the LABS suggesting that the free troposphere around Taiwan is frequently impacted by the long-range transport of biomass burning plumes via the westerly winds.

Chen, Sheng-Chieh; Hsu, Shih-Chieh; Tsai, Chuen-Jinn; Chou, Charles C.-K.; Lin, Neng-Huei; Lee, Chung-Te; Roam, Gwo-Dong; Pui, David Y. H.

2013-10-01

224

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

2013-04-09

225

Chemical and physical properties of ultrafine diesel exhaust particles sampled downstream of a catalytic trap.  

PubMed

The chemical and physical properties of exhaust particles produced by a Caterpillar 3176 C-12 heavy duty diesel engine equipped with a catalytic trap (CRT) are reported. The engine was operated at 600 Nm and 1500 rpm, using fuels containing 15 and 49 ppm sulfur. A two-stage dilution tunnel designed to simulate the reactions that occur when hot combustion products mix with cooler atmospheric air was used. Particle size distributions were measured using a scanning mobility particle sizer (SMPS) and nano-scanning mobility particle sizer (nano SMPS); a nanomicro-orifice uniform deposit impactor (nano MOUDI) collected size-resolved samples for gravimetric and chemical analysis. A nanometer tandem differential mobility analyzer (nano TDMA) was used to measure the volatility and hygroscopicity of 4-15 nm particles. These measurements confirm that the particles consisted primarily of sulfates. PMID:16999131

Grose, Melissa; Sakurai, Hiromu; Savstrom, Jake; Stolzenburg, Mark R; Watts, Winthrop F; Morgan, Christopher G; Murray, Ian P; Twigg, Martyn V; Kittelson, David B; McMurry, Peter H

2006-09-01

226

Cyto- and genotoxicity of ultrafine TiO2 particles in cultured human lymphoblastoid cells.  

PubMed

Titanium dioxide is frequently used in the production of paints, paper, plastics, welding rod-coating material, and cosmetics, because of its low toxicity. However, recent studies have shown that nano-sized or ultrafine TiO(2) (UF-TiO(2)) (<100 nm in diameter) can generate pulmonary fibrosis and lung tumor in rats. Cytotoxicity induced by UF-TiO(2) in rat lung alveolar macrophages was also observed. This generates great concern about the possible adverse effects of UF-TiO(2) for humans. The cytotoxicity and genotoxicity of UF-TiO(2) were investigated using the methyl tetrazolium cytotoxicity (MTT) assay, the population growth assay, the apoptosis assay by flow cytometry, the cytokinesis block micronucleus (CBMN) assay, the comet assay, and the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene mutation assay. WIL2-NS cells were incubated for 6, 24 and 48 h with 0, 26, 65 and 130 microg/ml UF-TiO(2). Significant decreases in viability were seen in the MTT assay at higher doses; for example, 61, 7 and 2% relative viability at 130 microg/ml for 6, 24 and 48-h exposure (P<0.01). A dose-dependent relationship was observed, while a time-dependent relationship was seen only at the highest dose (130 microg/ml) after exposure for 24 and 48 h. Treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the frequency of micronucleated binucleated cells (P<0.01). In addition, a significant reduction in the cytokinesis block proliferation index was observed by the CBMN assay (P<0.05). In the comet assay, treatment with 65 microg/ml UF-TiO(2) induced approximately 5-fold increases in olive tail moment (P<0.05). In the HPRT mutation assay, treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the mutation frequency (P<0.05). The results of this study indicate that UF-TiO(2) can cause genotoxicity and cytotoxicity in cultured human cells. PMID:17223607

Wang, Jing J; Sanderson, Barbara J S; Wang, He

2006-12-15

227

Ultrafine particle emission from incinerators: The role of the fabric filter  

Microsoft Academic Search

Incinerators are claimed to be responsible of particle and gaseous emissions: to this purpose Best Available Techniques (BAT) are used in the flue-gas treatment sections leading to pollutant emission lower than established threshold limit values. As regard particle emission, only a mass-based threshold limit is required by the regulatory authorities. However, in the last years the attention of medical experts

G. Buonanno; M. Scungio; L. Stabile; W. Tirler

2012-01-01

228

Laboratory Study of Simulated Atmospheric Transformations of Chromium in Ultrafine Combustion Aerosol Particles  

Microsoft Academic Search

While atmospheric particles can have adverse health effects, the reasons for this toxicity are largely unclear. One possible reason is that the particles can contain toxic metals such as chromium. Chromium exists in the environment in two major oxidation states: III, which is an essential nutrient, and VI, which is highly toxic and carcinogenic. Currently little is known about the

Michelle Werner; Peter Nico; Bing Guo; Ian Kennedy; Cort Anastasio

2006-01-01

229

High-resolution mobile monitoring of carbon monoxide and ultrafine particle concentrations in a near-road environment.  

PubMed

Assessment of near-road air quality is challenging in urban environments that have roadside structures, elevated road sections, or depressed roads that may impact the dispersion of traffic emissions. Vehicles traveling on arterial roadways may also contribute to air pollution spatial variability in urban areas. To characterize the nature of near-road air quality in a complex urban environment, an instrumented all-electric vehicle was deployed to perform high spatial- and temporal-resolution mapping of ultrafine particles (UFPs, particle diameter <100 nm) and carbon monoxide (CO). Sampling was conducted in areas surrounding a highway in Durham, NC, with multiple repeats of the driving route accomplished within a morning or evening commute time frame. Six different near-road transects were driven, which included features such as noise barriers, vegetation, frontage roads, and densely built houses. Under downwind conditions, median UFP and CO levels in near-road areas located 20-150 m from the highway were a factor of 1.8 and 1.2 higher, respectively, than in areas characterized as urban background. Sampling in multiple near-road neighborhoods during downwind conditions revealed significant variability in absolute UFP and CO concentrations as well as in the rate of concentration attenuation with increasing distance from the highway. During low-speed meandering winds, regional UFP and CO concentrations nearly doubled relative to crosswind conditions; however, near-road UFP levels were still higher than urban background levels by a factor of 1.2, whereas near-road CO concentrations were not significantly different than the urban background. PMID:20397562

Hagler, Gayle S W; Thoma, Eben D; Baldauf, Richard W

2010-03-01

230

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

231

Nitrogen dioxide and ultrafine particles dominate the biological effects of inhaled diesel exhaust treated by a catalyzed diesel particulate filter.  

PubMed

We studied the impact of a catalyzed diesel particulate filter (DPF) on the toxicity of diesel exhaust. Rats inhaled exhaust from a Cummins ISM heavy-duty diesel engine, with and without DPF after-treatment, or HEPA-filtered air for 4h, on 1 day (single exposure) and 3 days (repeated exposures). Biological effects were assessed after 2h (single exposure) and 20h (single and repeated exposures) recovery in clean air. Concentrations of pollutants were (1) untreated exhaust (-DPF), nitric oxide (NO), 43 ppm; nitrogen dioxide (NO2), 4 ppm; carbon monoxide (CO), 6 ppm; hydrocarbons, 11 ppm; particles, 3.2×10(5)/cm(3), 60-70nm mode, 269 ?g/m(3); (2) treated exhaust (+DPF), NO, 20 ppm; NO2, 16 ppm; CO, 1 ppm; hydrocarbons, 3 ppm; and particles, 4.4×10(5)/cm(3), 7-8nm mode, 2 ?g/m(3). Single exposures to -DPF exhaust resulted in increased neutrophils, total protein and the cytokines, growth-related oncogene/keratinocyte chemoattractant, macrophage inflammatory protein-1?, and monocyte chemoattractant protein-1 in lung lavage fluid, as well as increased gene expression of interleukin-6, prostaglandin-endoperoxide synthase 2, metallothionein 2A, tumor necrosis factor-?, inducible nitric oxide synthase, glutathione S-transferase A1, heme oxygenase-1, superoxide dismutase 2, endothelin-1 (ET-1), and endothelin-converting enzyme-1 in the lung, and ET- 1 in the heart. Ratio of bigET-1 to ET-1 peptide increased in plasma in conjunction with a decrease in endothelial nitric oxide synthase gene expression in the lungs after exposure to diesel exhaust, suggesting endothelial dysfunction. Rather than reducing toxicity, +DPF exhaust resulted in heightened injury and inflammation, consistent with the 4-fold increase in NO2 concentration. The ratio of bigET-1 to ET-1 was similarly elevated after -DPF and +DPF exhaust exposures. Endothelial dysfunction, thus, appeared related to particle number deposited, rather than particle mass or NO2 concentration. The potential benefits of particulate matter reduction using a catalyzed DPF may be confounded by increase in NO2 emission and release of reactive ultrafine particles. PMID:23897985

Karthikeyan, Subramanian; Thomson, Errol M; Kumarathasan, Prem; Guénette, Josée; Rosenblatt, Debbie; Chan, Tak; Rideout, Greg; Vincent, Renaud

2013-07-28

232

Development of ultrafine Ti-Fe-Sn in-situ composite with enhanced plasticity  

NASA Astrophysics Data System (ADS)

The present investigation is aimed at developing ultrafine eutectic/dendrite Ti-Fe-Sn in-situ composite with balanced combination of strength and plasticity. It also studies the microstructure evolution in the series of hypereutectic Ti-Fe-Sn ternary alloys. Sn concentration of these alloys has been varied from 0 - 10 atom% in the binary alloy (Ti71Fe29) keeping the Ti concentration fixed. These alloys have been prepared by arc melting under an Ar atmosphere on a water-cooled Cu hearth, which are subsequently suction cast in a split Cu-mold under an Ar atmosphere. Detailed X-ray diffraction (XRD) study shows the presence of TiFe, ?-Ti, and Ti3Sn phases. The SEM micrographs reveal that the microstructures consist of fine scale eutectic matrix (?-Ti and TiFe) with primary dendrite phases (TiFe and/or Ti3Sn) depending on concentration of Sn. ? -Ti forms as a eutectoid reaction product of ?-Ti. The room temperature uniaxial compressive test reveals simultaneous improvement in the strength (1942 MPa) and plasticity (13.1 %) for Ti71Fe26Sn3 ternary alloy. The fracture surface indicates a ductile mode of fracture for the alloy.

Mondal, B.; Samal, S.; Biswas, K.; Govind

2012-01-01

233

Development of Ultrafine-Grained Dual-Phase Steels: Mechanism of Grain Refinement During Intercritical Deformation  

NASA Astrophysics Data System (ADS)

Heavy deformation of metastable austenite (below Ae3) or both austenite and ferrite in the two-phase region (between Ar3 and Ar1) is known to develop an ultrafine ferrite grain structure with an average grain size of less than 3 ?m. Different dynamic softening mechanisms, such as dynamic recovery, dynamic recrystallization, and dynamic strain-induced austenite?ferrite transformation (DSIT), are responsible for such grain refinement. However, the sequence of those metallurgical events and the temperature range over which any particular mechanism dominates is not yet well understood. The current study throws some light on this aspect by applying heavy, single-pass compressive deformation (with true strain of 1.0) on the microalloyed steel samples over a temperature range of 1173 K to 873 K (900 °C to 600 °C) using a Gleeble simulator (Dynamic Systems Inc., Poestenkill, NY) and water quenching the samples immediately after deformation. The current study showed the dominating effect of the following mechanisms with respect to the deformation temperature: (1) DSIT followed by conventional dynamic recrystallization (Conv-DRX) of ferrite at higher deformation temperatures (?1073 K [800 °C]), (2) extended recovery and continuous dynamic recrystallization (Cont-DRX) of ferrite at intermediate deformation temperatures (~1023 K [750 °C]), and (3) simple dynamic recovery of ferrite at lower deformation temperatures (?923 K [650 °C]).

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

2013-05-01

234

Development of Ultrafine-Grained Dual-Phase Steels: Mechanism of Grain Refinement During Intercritical Deformation  

NASA Astrophysics Data System (ADS)

Heavy deformation of metastable austenite (below Ae3) or both austenite and ferrite in the two-phase region (between Ar3 and Ar1) is known to develop an ultrafine ferrite grain structure with an average grain size of less than 3 ?m. Different dynamic softening mechanisms, such as dynamic recovery, dynamic recrystallization, and dynamic strain-induced austenite?ferrite transformation (DSIT), are responsible for such grain refinement. However, the sequence of those metallurgical events and the temperature range over which any particular mechanism dominates is not yet well understood. The current study throws some light on this aspect by applying heavy, single-pass compressive deformation (with true strain of 1.0) on the microalloyed steel samples over a temperature range of 1173 K to 873 K (900 °C to 600 °C) using a Gleeble simulator (Dynamic Systems Inc., Poestenkill, NY) and water quenching the samples immediately after deformation. The current study showed the dominating effect of the following mechanisms with respect to the deformation temperature: (1) DSIT followed by conventional dynamic recrystallization (Conv-DRX) of ferrite at higher deformation temperatures (?1073 K [800 °C]), (2) extended recovery and continuous dynamic recrystallization (Cont-DRX) of ferrite at intermediate deformation temperatures (~1023 K [750 °C]), and (3) simple dynamic recovery of ferrite at lower deformation temperatures (?923 K [650 °C]).

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

2013-09-01

235

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

236

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

237

Sulfuric acid?layered ultrafine particles potentiate ozone?induced airway injury  

Microsoft Academic Search

Urban air pollution in the United States is composed of a complex mixture of particles and gases. Among the most prominent products of the atmospheric pollutants are sulfur oxides and ozone. In this report, we use two exposure protocols to examine the interaction between exposure to these two pollutants. In the first exposure regimen, guinea pigs were exposed to sulfuric

Lung Chi Chen; Patricia D. Miller; Hua Fuan Lam; John Guty; Mary O. Amdur

1991-01-01

238

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

239

Estimation of ultrafine particle concentrations at near-highway residences using data from local and central monitors  

PubMed Central

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.

Fuller, Christina H.; Brugge, Doug; Williams, Paige; Mittleman, Murray; Durant, John L.; Spengler, John D.

2012-01-01

240

Ultrafine PM emissions from natural gas, oxidation-catalyst diesel, and particle-trap diesel heavy-duty transit buses.  

PubMed

This paper addresses how current technologies effective for reducing PM emissions of heavy-duty engines may affect the physical characteristics of the particles emitted. Three in-use transit bus configurations were compared in terms of submicron particle size distributions using simultaneous SMPS measurements under two dilution conditions, a minidiluter and the legislated constant volume sampler (CVS). The compressed natural gas (CNG)-fueled and diesel particulate filter (DPF)-equipped diesel configurations are two "green" alternatives to conventional diesel engines. The CNG bus in this study did not have an oxidation catalyst whereas the diesel configurations (with and without particulate filter) employed catalysts. The DPF was a continuously regenerating trap (CRT). Particle size distributions were collected between 6 and 237 nm using 2-minute SMPS scans during idle and 55 mph steady-state cruise operation. Average particle size distributions collected during idle operation of the diesel baseline bus operating on ultralow sulfur fuel showed evidence for nanoparticle growth under CVS dilution conditions relative to the minidiluter. The CRT effectively reduced both accumulation and nuclei mode concentrations by factors of 10-100 except under CVS dilution conditions where nuclei mode concentrations were measured during 55 mph steady-state cruise that exceeded baseline diesel concentrations. The CVS data suggest some variability in trap performance. The CNG bus had accumulation mode concentrations 10-100x lower than the diesel baseline but often displayed large nuclei modes, especially under CVS dilution conditions. Partly this may be explained by the lack of an oxidation catalyst on the CNG, but differences between the minidiluter and CVS size distributions suggest that dilution ratio, temperature-related wall interactions, and differences in tunnel background between the diluters contributed to creating nanoparticle concentrations that sometimes exceeded diesel baseline concentrations when driving under load. The results do not support use of CVS dilution methodology for ultrafine particle sampling, and, despite attention to collection of tunnel blanks in this study, results indicate that a protocol needs to be determined and prescribed for taking into account tunnel blank "emissions" to obtain meaningful comparisons between different technologies. Of critical importance is determining how temperature differences between tunnel blank and test cycle sampling compare in terms of background particle numbers. Total particle number concentrations for the minidiluter sampling point were not significantly different for the two alternative technologies when considering all the steady-cycle data collected. Concentrations ranged from 0.8 to 3 x 10(6) for the baseline bus operating on ultralow sulfur fuel, from 0.5 to 9 x 10(4) for the diesel bus equipped with the CRT filter, and from 1 to 8 x 10(4) particles/cc for the CNG bus. PMID:12523418

Holmén, Britt A; Ayala, Alberto

2002-12-01

241

Particle number size distribution in the eastern Mediterranean: Formation and growth rates of ultrafine airborne atmospheric particles  

NASA Astrophysics Data System (ADS)

Particle number concentration was measured between June 2009 and June 2010 at Akrotiri research station in a rural/suburban region of western Crete (Greece). Overall, the available data covered 157 days during the aforementioned period of measurements. The objectives were to study the number size distribution characteristics of ambient aerosols and furthermore to identify new particle formation events and to evaluate particle formation rates and growth rates of the newborn particles. Aerosol particles with mobility diameters between 10 and 1100 nm were measured using a Scanning Mobility Particle Sizer (SMPS) system. Measurements were performed at ambient relative humidities. The median total particle number concentration was 525 #/cm3 whereas the number concentration ranged between 130 #/cm3 and 9597 #/cm3. The average percentage of particles with diameters between 10 nm and 100 nm (N10–100) to total particles was 53% during summer and spring, but reached 80% during winter. Maximum average contribution of nano-particles (10 nm < Dp < 50 nm) to total particles was recorded also in winter and was attributed partly to the effect of local heating. Furthermore, back trajectories (HYSPLIT model) showed that different air mass origins are linked to different levels of particle number concentrations, with higher values associated with air masses passing from polluted areas before reaching the Akrotiri station. Modal analysis of the measured size distribution data revealed a strong nucleation mode during winter (15–25 nm), which can be correlated with emissions from local sources (domestic heating). The nucleation mode was observed also during the spring campaigns and was partly linked to new particle formation events. On the contrary, an accumulation mode (80–120 nm) prevailed in the measurements during summer campaigns, when the station area was influenced by polluted air masses arriving mainly from Eastern Europe. In total, 13 new particle formation events were recorded during the 157 days of measurements. Nucleation events were associated with low values of N100 particle number concentration and reduced coagulation sinks. Mean growth and formation rates were calculated and showed values equal to 6 nm hr?1 and 13 cm?3 s?1, respectively.

Kopanakis, I.; Chatoutsidou, S. E.; Torseth, K.; Glytsos, T.; Lazaridis, M.

2013-10-01

242

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

243

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

244

Influence of channel angle on the development of ultrafine grains in equal-channel angular pressing  

Microsoft Academic Search

Equal-channel angular pressing provides a convenient procedure for introducing an ultrafine grain size into a material. Using samples of pure Al, tests were conducted to determine the influence of the channel angle ?, defined as the angle of intersection of the two channels within the die, on the subsequent microstructure attained by pressing. Experiments were performed using dies having channel

Kiyotaka Nakashima; Zenji Horita; Minoru Nemoto; Terence G. Langdon

1998-01-01

245

Combustion of Ultrafine Aluminum in Air  

Microsoft Academic Search

The paper reports results of studying the combustion of ultrafine aluminum (surface average diameter of particles is ˜ 0.1 µm) in a sealed bomb at an initial air pressure of 1 atm. The combustion proceeds in two stages, similarly to combustion in air. It is shown that during the two-stage combustion of ultrafine aluminum powder in the bomb, the mass

A. P. Il'in; A. A. Gromov; V. I. Vereshchagin; E. M. Popenko; V. A. Surgin; H. Lehn

2001-01-01

246

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

Microsoft Academic Search

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

Tina M Sager; Vincent Castranova

2009-01-01

247

How do the indoor size distributions of airborne submicron and ultrafine particles in the absence of significant indoor sources depend on outdoor distributions?  

PubMed

Although almost all epidemiological studies of smaller airborne particles only consider outdoor concentrations, people in Central Europe actually spend most of their time indoors. Yet indoor pollutants such as organic gases, allergens and dust are known to play a prominent role, often affecting human health more than outdoor ones. The aim of this study was to ascertain how the indoor particle size distributions of submicron and ultrafine particles correlate with the outdoor concentrations in the absence of significant indoor sources. A typical indoor particle size distribution pattern has one or two modes. In the absence of significant indoor activities such as smoking, cooking etc., outdoor particles were found to be a very important source of indoor particles. The study shows that in the absence of significant indoor sources, the number of indoor concentrations of particles in this size range are clearly lower than the outdoor concentrations. This difference is greater, the higher the number of outdoor concentrations. However, the drop in concentration is not uniform, with the decrease in concentration of smaller particles exceeding that of larger ones. By contrast, the findings with larger particle sizes (diameter > 1 microm) exhibit rather linear concentration decreases. The non-uniform drop in the number of concentrations from outdoors to indoors in our measurements considering smaller particles ( >0.01 microm) is accompanied by a shift of the concentration maxima to larger particle diameters. PMID:12756011

Franck, U; Herbarth, O; Wehner, B; Wiedensohler, A; Manjarrez, M

2003-06-01

248

Exposure assessment of a cyclist to PM 10 and ultrafine particles  

Microsoft Academic Search

Estimating personal exposure to air pollution is a crucial component in identifying high-risk populations and situations. It will enable policy makers to determine efficient control strategies. Cycling is again becoming a favorite mode of transport both in developing and in developed countries due to increasing traffic congestion and environmental concerns. In Europe, it is also seen as a healthy sports

P. Berghmans; N. Bleux; L. Int Panis; V. K. Mishra; R. Torfs; M. Van Poppel

2009-01-01

249

Modeling of in situ ultrafine atmospheric particle formation in the eastern United States  

NASA Astrophysics Data System (ADS)

The creation of new atmospheric particles from in situ nucleation influences climate through cloud-aerosol interactions and may negatively impact human health. Although recent observations show that nucleation is widespread in the eastern United States, the corresponding pathways remain uncertain. Combining extensive field measurements in Pittsburgh, Pennsylvania, with an aerosol dynamics and chemistry model assuming ternary NH3-H2SO4-H2O nuclei formation, we show excellent model-measurement agreement and predictive capability. The ternary NH3-H2SO4-H2O nucleation model is successful in predicting the presence or lack of nucleation on 19 out of 19 days with complete data sets in July 2001 and on 25 out of 29 days in January 2002. Reductions of ammonia emissions are predicted to decrease the frequency of nucleation events during both summer and winter, with a more dramatic effect during the summer. The response to changes in emissions of sulfur dioxide during the summer is counterintuitive. Reductions of sulfur dioxide and the resulting sulfate by up to 40% actually increase the frequency of the summer nucleation events. Modeling predicts the opposite effect in winter, with reductions of sulfur dioxide leading to fewer nucleation events.

Gaydos, Timothy M.; Stanier, Charles O.; Pandis, Spyros N.

2005-04-01

250

Development and characterization of metal-diboride-based composites toughened with ultra-fine SiC particulates  

Microsoft Academic Search

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 ZrB2 or a mixture of ZrB2 and HfB2. 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

Frédéric Monteverde; Alida Bellosi

2005-01-01

251

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

252

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

253

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

254

Ultrafine particles affect the balance of endogenous pro- and anti-inflammatory lipid mediators in the lung: in-vitro and in-vivo studies  

PubMed Central

Background Exposure to ultrafine particles exerts diverse harmful effects including aggravation of pulmonary diseases like asthma. Recently we demonstrated in a mouse model for allergic airway inflammation that particle-derived oxidative stress plays a crucial role during augmentation of allergen-induced lung inflammation by ultrafine carbon particle (UfCP) inhalation. The mechanisms how particle inhalation might change the inflammatory balance in the lungs, leading to accelerated inflammatory reactions, remain unclear. Lipid mediators, known to be immediately generated in response to tissue injury, might be strong candidates for priming this particle-triggered change of the inflammatory balance. Methods We hypothesize that inhalation of UfCP may disturb the balance of pro- and anti-inflammatory lipid mediators in: i) a model for acute allergic pulmonary inflammation, exposing mice for 24 h before allergen challenge to UfCP inhalation (51.7 nm, 507 ?g/m3), and ii) an in-vitro model with primary rat alveolar macrophages (AM) incubated with UfCP (10 ?g/1 x 106 cells/ml) for 1 h. Lungs and AM were analysed for pro- and anti-inflammatory lipid mediators, namely leukotriene B4 (LTB4), prostaglandin E2 (PGE2), 15(S)-hydroxy-eicosatetraenoic acid (15(S)-HETE), lipoxin A4 (LXA4) and oxidative stress marker 8-isoprostane by enzyme immunoassays and immunohistochemistry. Results In non-sensitized mice UfCP exposure induced a light non-significant increase of all lipid mediators. Similarly but significantly in rat AM all lipid mediators were induced already within 1 h of UfCP stimulation. Also sensitized and challenge mice exposed to filtered air showed a partially significant increase in all lipid mediators. In sensitized and challenged mice UfCP exposure induced highest significant levels of all lipid mediators in the lungs together with the peak of allergic airway inflammation on day 7 after UfCP inhalation. The levels of LTB4, 8-isoprostane and PGE2 were significantly increased also one day after UfCP exposure. Immunohistochemistry localized highest concentrations of PGE2 especially in AM one day after UfCP exposure. Conclusion Our results suggest that UfCP exposure affects the balance between pro- and anti-inflammatory lipid mediators. In allergic mice, where the endogenous balance of pro- and anti-inflammatory mediators is already altered, UfCP exposure aggravates the inflammation and the increase in anti-inflammatory, pro-resolving lipid mediators is insufficient to counterbalance the extensive inflammatory response. This may be a contributing mechanism that explains the increased susceptibility of asthmatic patients towards particle exposure.

2012-01-01

255

Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions. Quarterly technical progress report, January 1, 1991--March 31, 1991  

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. In the first quarterly report for this program the concept behind our approach was detailed, the structure of the program was presented, key technical issues were identified, preliminary designs were outlined, and technical progress was discussed. All progress made during the second quarter of this program related to experiment design of the proposed supercritical expansion technique for generating ultra-fine, iron compound, catalyst particles. This second quarterly report, therefore, presents descriptions of the final designs for most system components; diagnostic approaches and designs for determining particles size and size distributions, and the composition of the pre-expansion supercritical solution; and the overall technique progress made during this reporting period. 6 refs., 15 figs., 1 tab.

Not Available

1991-09-01

256

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

257

Production of ultrafine atmospheric pressure plasma jet with nano-capillary  

Microsoft Academic Search

The atmospheric pressure plasma jet (APPJ) has been developed to apply to the ultrafine process for future material processing. In this study, we tried to reduce the diameter of APPJs by using micro- or nano-capillary tubes. To measure the existence of the bullet-like charged particles from the capillary tip, the plasma flow generated from capillary tubes with a diameter of

Ryota Kakei; Akihisa Ogino; Futoshi Iwata; Masaaki Nagatsu

2010-01-01

258

Simulating ultrafine particle formation in Europe using a regional CTM: Contribution of primary emissions versus secondary formation to aerosol number concentrations  

NASA Astrophysics Data System (ADS)

PMCAMx-UF, a 3-D regional chemical transport model with detailed aerosol microphysics, was applied to the European domain for the first time, in order to simulate particle number concentrations. Results for the month of May 2008 are presented during which an intensive measurement campaign was performed in Europe. The focus of this work was to better understand the relative contribution of direct emissions and new particle formation to regional aerosol number concentrations in Europe during a photochemically active period. Results show that nucleation events start generally from Eastern Europe and move to the west following the photochemical activity. The model predicts nucleation events that occur over scales of hundreds up to thousands of kilometers mainly in the high SO2 areas of the Balkans and Southeast Europe as well as more localized events in west and central Europe. Aerosol nucleation is predicted to increase the total particle number concentration by a factor of 20 or more in some of these wide areas and by a factor of 6.5 for particles larger than 10 nm. The effect of nucleation in the lower troposphere on particle number above 100 nm is, on average, small with the exception of the Mediterranean area where the model predicts that nucleation can increase the number concentration of CCN-sized particles by up to 20%. Model evaluation was conducted against ground based hourly measurements from 7 sites. The model agrees encouragingly well with the particle number concentration ground measurements, reproducing more than 70% of the (hourly) data points for N10 within a factor of 2. However, a systematic underprediction of N100 implies the need for improvement of either the size distribution of the emissions and/or the growth of the ultrafine particles to this size range. Approximately 50% of particles above 10 nm are predicted to come from aerosol nucleation. Including nucleation in the simulation has a minor effect in the predictions of N100 at all studied sites, ranging from -4% to +3% while the effect on N50 is more pronounced only in sites that are influenced by local pollution and have high aerosol number concentrations. Results from the 3 nucleation mechanisms that were tested suggest that i) the ternary mechanism performs better than the activation or the kinetic, and ii) additional improvements in the diurnal and geographical distribution of the particle number emission inventory are needed.

Fountoukis, C.; Riipinen, I.; Denier van der Gon, H.; Charalampidis, P. E.; Pilinis, C.; Pandis, S. N.

2012-04-01

259

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

260

Gas Jet Deposition of Multicomponent Ultrafine Microstructures.  

National Technical Information Service (NTIS)

The potential technological importance of multicomponent ultrafine microstructures makes it essential to develop methods of formation which permit both higher growth rates and improved control over material properties. During the course of our Phase I res...

B. L. Halpern J. J. Schmitt

1988-01-01

261

Influence of ozone concentration and temperature on ultra-fine particle and gaseous volatile organic compound formations generated during the ozone-initiated reactions with emitted terpenes from a car air freshener.  

PubMed

Experiments were conducted to identify the emissions from the car air freshener and to identify the formation of ultra-fine particles and secondary gaseous compounds during the ozone-initiated oxidations with emitted volatile organic compounds (VOCs). The identified primary constituents emitted from the car air freshener in this study were alpha-pinene, beta-pinene, p-cymene, and limonene. Formation of ultra-fine particles (4.4-160 nm) was observed when ozone was injected into the chamber containing emitted monoterpenes from the air freshener. Particle number concentrations, particle mass concentrations, and surface concentrations were measured in time dependent experiments to describe the particle formation and growth within the chamber. The irritating secondary gaseous products formed during the ozone-initiated reactions include formaldehyde, acetaldehyde, acrolein, acetone, and propionaldehyde. Ozone concentration (50 and 100 ppb) and temperature (30 and 40 degrees C) significantly affect the formation of particles and gaseous products during the ozone-initiated reactions. The results obtained in this study provided an insight on the potential exposure of particles and irritating secondary products formed during the ozone-initiated reaction to passengers in confined spaces. PMID:18336999

Lamorena, Rheo B; Lee, Woojin

2008-02-07

262

Investigations of percutaneous uptake of ultrafine TiO2 particles at the high energy ion nanoprobe LIPSION  

NASA Astrophysics Data System (ADS)

Micronised TiO2 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 TiO2 particles can pass through the uppermost horny skin layer (stratum corneum) via intercellular channels and penetrate into deeper vital skin layers. Accumulations of TiO2 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 TiO2 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 TiO2 particles into the skin. In these measurements a penetration of TiO2 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 TiO2 was detected inside. The TiO2 particle concentration in the stratum spinosum was below the minimum detection limit of about 1 particle/?m2. These findings show the importance of coating the TiO2 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

263

Ultrafine particles and associated pollutants on roadways and in community air of Los Angeles California, Beijing China, and the Los Angeles International Airport  

NASA Astrophysics Data System (ADS)

Particles smaller than 10 microm in diameter are harmful to health. However, the smallest of these particles, ultrafine particles (UFP), equal to or smaller than 100 nm, may be especially harmful. Most are emitted by combustion sources, with transportation sources being a dominant contributor. While these particles have recently been under intense research, little is known regarding UFP concentrations or its components where people live, work, and commute. This dissertation reports on investigations of UFP and other pollutants in transportation-dominated areas. Included are findings from on-road, near-road and community monitoring studies performed in two megacities: Los Angeles, California and Beijing, China. A common feature of these studies was the application of advanced technologies to gather time-resolved measurements. An important finding made in Los Angeles was that real-time pollutant measurements could be made on busy roadways. UFP size distribution measurements made on a freeway with heavy-duty truck traffic demonstrated that UFP were much higher than on other highways or in community air. Nitric oxide (NO) levels were also much higher in these truck-dominated microenvironments. High correlations were found between UFP, black carbon (BC), particle counts, (NO), and particulate polycyclic aromatic hydrocarbons. Monitoring at Los Angeles International Airport demonstrated that aircraft are important sources of UFP. Elevated UFP counts were found 900 meters from a runway used for take offs, while smaller values were found 500 meters downwind of a runway used for landings. These measurements showed a persistence of UFP at the community boundary in excess of measurements from roadside studies. A peak UFP measurement of 4.8 million particles cm -3 was made approximately 75 meters from a jet aircraft waiting to takeoff. Measurements made in Beijing demonstrated that heavy-duty diesel truck activity severely impacts community air quality. Black carbon was a marker of this activity. Levels of BC were approximately 5 microg m-3 in community air when trucks were not allowed in the city and exceeded 10--30 microg m-3 when trucks entered the city. On-road measurements made on expressways used by diesel-fueled trucks and light-duty gasoline-powered vehicles provided an opportunity to make emission estimates for carbon monoxide, BC, and UFP.

Westerdahl, Frederick Dane

264

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

265

Ultrafine PM Emissions from Natural Gas, Oxidation-Catalyst Diesel, and Particle-Trap Diesel Heavy-Duty Transit Buses  

Microsoft Academic Search

This paper addresses how current technologies effective for reducing PM emissions of heavy-duty engines may affect the physical characteristics of the particles emitted. Three in-use transit bus configurations were compared in terms of submicron particle size distributions using simultaneous SMPS measurements under two dilution conditions, a minidiluter and the legislated constant volume sampler (CVS). The compressed natural gas (CNG) -fueled

BRITT A. H OLME; ALBERTO A YALA

266

Fine and ultrafine particles at a near-free tropospheric environment over the high-altitude station Hanle in the Trans-Himalaya: New particle formation and size distribution  

NASA Astrophysics Data System (ADS)

Number-size distributions of ultrafine, fine, and accumulation mode aerosols in the size range 5-1300 nm have been measured regularly from the pristine, high-altitude (for 4520 m above mean sea level) station Hanle in the Trans-Himalaya during the summer and autumn (August-November) 2009. The total number concentration ranged from 80 to 8000 cm-3 with a mean value of 1150 cm-3. Examination of the temporal variations of the size distributions indicated that formation of new ultrafine particles from the precursor gases (probably transported from the valley regions) was highly probable during the forenoon hours of the day, especially during the summer when the insolation was abundant, the process becoming increasingly less efficient as the season progressed toward winter. The time of occurrence of maximum concentration was generally during the forenoon, a few hours after sunrise, and this time shifted to later parts of the day as the season progressed toward winter, probably associated with later sunrise and low solar elevations. The number-size distributions revealed two prominent modes: a nucleation mode with mode diameter at ˜16 nm and a consistent accumulation mode with the mode diameter ranging between 115 and 150 nm. Examining the temporal features with the air mass types, it was noticed that the number concentration increased, and the accumulation mode broadened when west Asian air mass prevailed. In summer (during August) the number concentrations tended to higher values associated with air mass from the Indian origin. The ratio of the Aitken to accumulation mode concentration indicated that the aerosol particles existing over the site are aged.

Moorthy, K. Krishna; Sreekanth, V.; Prakash Chaubey, Jai; Gogoi, Mukunda M.; Suresh Babu, S.; Kumar Kompalli, Sobhan; Bagare, S. P.; Bhatt, Bhuvan C.; Gaur, Vinod K.; Prabhu, T. P.; Singh, N. S.

2011-10-01

267

The formation of ultra-fine particles during ozone-initiated oxidations with terpenes emitted from natural paint.  

PubMed

The formation of secondary products during the ozone-initiated oxidations with biogenic VOCs emitted from natural paint was investigated in this study. Mass spectrometry and infrared spectroscopy measurements have shown that the major components of gas-phase chemicals emitted from natural paint are monoterpenes including alpha- and beta-pinenes, camphene, p-cymene, and limonene. A significant formation of gaseous carbonyl products and nano-sized particles (4.4-168nm) was observed in the presence of ozone. Carboxylic acids were also observed to form during the reactions (i.e. formic acid at 0.170ppm and acetic acid at 0.260ppm). The formation of particles increased as the volume of paint introduced into a reaction chamber increased. A secondary increase in the particle number concentration was observed after 440min, which suggests further partitioning of oxidation products (i.e. carboxylic acids) into the particles previously existing in the reaction chamber. The growth of particles increased as the mean particle diameter and particle mass concentrations increased during the reaction. The experimental results obtained in this study may provide insight into the potential exposure of occupants to irritating chemical compounds formed during the oxidations of biogenic VOCs emitted from natural paint in indoor environments. PMID:16908097

Lamorena, Rheo B; Jung, Sang-Guen; Bae, Gwi-Nam; Lee, Woojin

2006-07-04

268

Effect of advanced aftertreatment for PM and NOx reduction on heavy-duty diesel engine ultrafine particle emissions.  

PubMed

Four heavy-duty and medium-duty diesel vehicles were tested in six different aftertreament configurations using a chassis dynamometer to characterize the occurrence of nucleation (the conversion of exhaust gases to particles upon dilution). The aftertreatment included four different diesel particulate filters and two selective catalytic reduction (SCR) devices. All DPFs reduced the emissions of solid particles by several orders of magnitude, but in certain cases the occurrence of a volatile nucleation mode could increase total particle number emissions. The occurrence of a nucleation mode could be predicted based on the level of catalyst in the aftertreatment, the prevailing temperature in the aftertreatment, and the age of the aftertreatment. The particles measured during nucleation had a high fraction of sulfate, up to 62% of reconstructed mass. Additionally the catalyst reduced the toxicity measured in chemical and cellular assays suggesting a pathway for an inverse correlation between particle number and toxicity. The results have implications for exposure to and toxicity of diesel PM. PMID:21322629

Herner, Jorn Dinh; Hu, Shaohua; Robertson, William H; Huai, Tao; Chang, M-C Oliver; Rieger, Paul; Ayala, Alberto

2011-02-15

269

Study of an ultrafine w-EDM technique  

Microsoft Academic Search

A precision ultrafine w-EDM (wire electrical discharge machining) technique specifically for machining intricate parts and structures is developed in this paper. A thumb-sized and versatile w-EDM device equipped with a complete control system for wire tension (ultrafine tungsten wire of 13 µm diameter) is designed and employed for the study of ultrafine w-EDM. The tension of the wire electrode is

Shun-Tong Chen; Hong-Ye Yang; Chih-Wei Du

2009-01-01

270

Dose-controlled exposure of A549 epithelial cells at the air–liquid interface to airborne ultrafine carbonaceous particles  

Microsoft Academic Search

The geometry of commercially available perfusion chambers designed for harbouring three membrane-based cell cultures was modified for reliable and dose-controlled air–liquid interface (ALI) exposures. Confluent A549 epithelial cells grown on membranes were integrated in the chamber system and supplied with medium from the chamber bottom. Cell viability was not impaired by the conditions of ALI exposure without particles. Expression of

E. Bitterle; E. Karg; A. Schroeppel; W. G. Kreyling; A. Tippe; G. A. Ferron; O. Schmid; J. Heyder; K. L. Maier; T. Hofer

2006-01-01

271

The formation of ultra-fine particles during ozone-initiated oxidations with terpenes emitted from natural paint  

Microsoft Academic Search

The formation of secondary products during the ozone-initiated oxidations with biogenic VOCs emitted from natural paint was investigated in this study. Mass spectrometry and infrared spectroscopy measurements have shown that the major components of gas-phase chemicals emitted from natural paint are monoterpenes including ?- and ?-pinenes, camphene, p-cymene, and limonene. A significant formation of gaseous carbonyl products and nano-sized particles

Rheo B. Lamorena; Sang-Guen Jung; Gwi-Nam Bae; Woojin Lee

2007-01-01

272

Parameterization of meteorological variables in the process of infiltration of outdoor ultrafine particles into a residential building.  

PubMed

As part of the Brooklyn Traffic Real-Time Ambient Pollutant Penetration and Environmental Dispersion (B-TRAPPED) study, a field investigation was conducted of the mechanisms involved in infiltration of outdoor particles (0.02 microm to 1 microm) into a near-highway urban residential building. Using continuous real-time total number concentration time-series data measured simultaneously at multiple outdoor and indoor locations, the infiltration time was estimated for various indoor sites by using the cross-correlation analysis method. The effects of meteorological variables on infiltration times were also characterized at given locations. In particular, infiltration time was examined as a function of outdoor mean rooftop wind speed. Outdoor and indoor temperature and relative humidity were also investigated in relation to infiltration times. Our results showed that outdoor wind speed was the dominant meteorological parameter affecting the infiltration rate, but no correlation was found with temperature. The outdoor-indoor PM concentration ratio was found to be significantly different for the first and second floors of the test building. Finally, we determined the effectiveness of a protective shelter-in-place area inside the building by calculating infiltration times into the area. We found that the shelter-in-place area offered some protection against the infiltrating particles because of increased attenuation of the outdoor concentration. PMID:20024016

Hahn, Intaek; Brixey, Laurie A; Wiener, Russell W; Henkle, Stacy W

2009-10-29

273

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

274

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 suggested potential lung injury, the severity of which could be correlated with the carbon (soot) content of the ultrafines. This increased toxicity is consistent with theories in which the presence of carbon mediates transition metal (i.e., Fe) complexes, as revealed in this work by TEM and XAFS spectroscopy, promoting reactive oxygenspecies, oxidation-reduction cycling, and oxidative stress. 24 refs., 7 figs.

William P. Linak; Jong-Ik Yoo; Shirley J. Wasson; Weiyan Zhu; Jost O.L. Wendt; Frank E. Huggins; Yuanzhi Chen; Naresh Shah; Gerald P. Huffman; M. Ian Gilmour [US Environmental Protection Agency, Research Triangle Park, NC (United States). National Risk Management Research Laboratory

2007-07-01

275

A Handheld Electrostatic Precipitator for Sampling Airborne Particles and Nanoparticles  

Microsoft Academic Search

Researchers at NIOSH are developing methods for characterizing ultrafine aerosols in workplaces. One method includes the detailed analysis of collected particles using electron microscopy (EM). In order to collect samples for EM at remote workplaces including mining and manufacturing facilities, researchers have developed a handheld electrostatic precipitator (ESP) particle sampler capable of collecting airborne particles including nanoscale materials, for subsequent

Arthur Miller; Garrett Frey; Grant King; Carl Sunderman

2010-01-01

276

The role of oxidative stress in the prolonged inhibitory effect of ultrafine carbon black on epithelial cell function  

Microsoft Academic Search

Respired ultrafine particles induce a greater inflammation in rat lungs than fine particles; we have hypothesized that this is due to their comparatively huge number and surface area for the production of free radicals. We tested this hypothesis by studying the effects of fine and ultrafine (uf) carbon black (CB) particles in comparison with quartz on A549 human type II

V. Stone; J. Shaw; D. M. Brown; W. MacNee; S. P. Faux; K. Donaldson

1998-01-01

277

Increased inflammation and intracellular calcium caused by ultrafine carbon black is independent of transition metals or other soluble components  

Microsoft Academic Search

OBJECTIVESParticulate air pollution has been shown to cause adverse health effects, and the ultrafine particle component has been implicated. The aim of the present study was to investigate whether an ultrafine particle exerted its effects through transition metals or other soluble factors released from the surface of the particles.METHODSBoth in vitro and in vivo models were used to test the

D M Brown; V Stone; P Findlay; W MacNee; K Donaldson

2000-01-01

278

Simulation of particles transport and coagulation during the RESS process  

Microsoft Academic Search

The rapid expansion of supercritical solution (RESS) is a promising process for the production of small particles with a narrow size distribution. It involves an expansion of a supercritical solution through a small nozzle to generate a rapid nucleation and then the formation of ultrafine particles. The particles are transported by a powerful jet developed in the expansion chamber. The

A. Ben Moussa; H. Ksibi; M. Baccar

2008-01-01

279

Development of an Ultra-fine Coal Dewatering Technology and an Integrated Flotation-Dewatering System for Coal Preparation Plants  

SciTech Connect

The project proposal was approved for only the phase I period. The goal for this Phase I project was to develop an industrial model that can perform continuous and efficient dewatering of fine coal slurries of the previous flotation process to fine coal cake of {approx}15% water content from 50-70%. The feasibility of this model should be demonstrated experimentally using a lab scale setup. The Phase I project was originally for one year, from May 2005 to May 2006. With DOE approval, the project was extended to Dec. 2006 without additional cost from DOE to accomplish the work. Water has been used in mining for a number of purposes such as a carrier, washing liquid, dust-catching media, fire-retardation media, temperature-control media, and solvent. When coal is cleaned in wet-processing circuits, waste streams containing water, fine coal, and noncombustible particles (ash-forming minerals) are produced. In many coal preparation plants, the fine waste stream is fed into a series of selection processes where fine coal particles are recovered from the mixture to form diluted coal fine slurries. A dewatering process is then needed to reduce the water content to about 15%-20% so that the product is marketable. However, in the dewatering process currently used in coal preparation plants, coal fines smaller than 45 micrometers are lost, and in many other plants, coal fines up to 100 micrometers are also wasted. These not-recovered coal fines are mixed with water and mineral particles of the similar particle size range and discharged to impoundment. The wasted water from coal preparation plants containing unrecoverable coal fine and mineral particles are called tailings. With time the amount of wastewater accumulates occupying vast land space while it appears as threat to the environment. This project developed a special extruder and demonstrated its application in solid-liquid separation of coal slurry, tailings containing coal fines mostly less than 50 micron. The extruder is special because all of its auger surface and the internal barrier surface are covered with the membranes allowing water to drain and solid particles retained. It is believed that there are four mechanisms working together in the dewatering process. They are hydrophilic diffusion flow, pressure flow, agitation and air purging. Hydrophilic diffusion flow is effective with hydrophilic membrane. Pressure flow is due to the difference of hydraulic pressure between the two sides of the membrane. Agitation is provided by the rotation of the auger. Purging is achieved with the air blow from the near bottom of the extruder, which is in vertical direction.

Wu Zhang; David Yang; Amar Amarnath; Iftikhar Huq; Scott O'Brien; Jim Williams

2006-12-22

280

Relationship of pulmonary toxicity and carcinogenicity of fine and ultrafine granular dusts in a rat bioassay  

PubMed Central

The current carcinogenicity study with female rats focused on the toxicity and carcinogenicity of intratracheally instilled fine and ultrafine granular dusts. The positive control, crystalline silica, elicited the greatest magnitude and progression of pulmonary inflammatory reactions, fibrosis and the highest incidence of primary lung tumors (39.6%). Addition of poly-2-vinylpyridine-N-oxide decreased inflammatory responses, fibrosis, and the incidence of pulmonary tumors induced by crystalline quartz to 21.4%. After repeated instillation of soluble, ultrafine amorphous silica (15 mg) a statistically significant tumor response (9.4%) was observed, although, the inflammatory response in the lung was not as persistently severe as in rats treated with carbon black. Instillation of ultrafine carbon black (5 mg) caused a lung tumor incidence of 15%. In contrast to a preceding study using a dose of 66 mg coal dust, lung tumors were not detected after exposure to the same coal dust at a dose of 10 mg in this study. Pulmonary inflammatory responses to coal dust were very low indicating a mechanistic threshold for the development of lung tumors connected with particle related chronic inflammation. The animals treated with ultrafine carbon black and ultrafine amorphous silica showed significantly more severe lesions in non-cancerous endpoints when compared to animals treated with fine coal dust. Furthermore, carbon black treated rats showed more severe non-cancerous lung lesions than amorphous silica treated rats. Our data show a relationship between tumor frequencies and increasing scores when using a qualitative scoring system for specific non-cancerous endpoints such as inflammation, fibrosis, epithelial hyperplasia, and squamous metaplasia.

Kolling, Angelika; Ernst, Heinrich; Rittinghausen, Susanne; Heinrich, Uwe

2011-01-01

281

A novel technique for evaluating cleaned fine and ultrafine coal. Final technical report, 1 September 1991--31 August 1992  

SciTech Connect

The increasing demand for cleaner coals requires that coals be crushed to fine ({minus}100 mesh--0.15 mm) and ultrafine ({minus}325 mesh--0.045 mm) sizes to liberate more of the fine-grained mineral matter including pyrite. However, such small coal particles can not be analyzed in the standard washability analysis. The purpose of this study is to develop a washability analysis system for fine and ultrafine coal particles using Density Gradient Centrifugation (DGC) and Thermal Gravimetric Analysis (TGA) techniques. The main conclusion of this project is that it has clearly been demonstrated that the density gradient centrifugation process can be used to generate usable washability data on fine and ultrafine coals. Specific conclusions are: (1) A single DGC run gives all twelve density fractions (at 0.05 gm/ml increments) for a washability analysis of a single size fraction; (2) Recovery from the DGC runs is usually sufficient for ash and sulfur analysis; (3) DGC washability analysis can be used to define the limits of washability and to screen coals for ultrafine use.

Crelling, J.C.; Hippo, E.J. [Southern Illinois Univ., Carbondale, IL (United States)

1992-12-31

282

Initial study of dry ultrafine coal beneficiation utilizing triboelectric charging with subsequent electrostatic separation  

SciTech Connect

A novel, dry process using electrostatics to beneficiate ultrafine coal is being developed by the Coal Preparation Division at the Pittsburgh Energy Technology Center. The historical concept of triboelectricity and its eventual use as a means of charging coal for electrostatic separation will be discussed. Test data from a first-generation and a second-generation Tribo-Electrostatic separator are presented showing the effects of feed particle size, separator voltage, solids concentration in air, and particle velocity on separation performance. 10 refs., 10 figs., 9 tabs.

Link, T.A.; Killmeyer, R.P.; Elstrodt, R.H.; Haden, N.H.

1990-10-01

283

Synthesis of ultrafine particles of intermetallic compounds by the vapor-phase magnesium reduction of chloride mixtures: Part II. Nickel aluminides  

Microsoft Academic Search

The new chemical synthesis process developed in this laboratory for the preparation of the fine powders of intermetallic compounds\\u000a by the vapor-phase reduction of mixtures of constituent metal chlorides by magnesium vapor, described in Part I for titanium\\u000a aluminides, was applied to the synthesis of nickel aluminide particles. NiAl, NiAl3, and Ni2Al3 were formed by reducing mixtures of NiCl2 and

H. Y. Sohn; S. Paldey

1998-01-01

284

Intercomparison of Four Methods to Determine Size Distributions of Low-Concentration (? 100 cm), Ultrafine Aerosols (3 < Dp < 10 nm) with Illustrative Data from the Arctic  

Microsoft Academic Search

Four different methods for measuring ultrafine particle size distributions in the 3–10-nm particle diameter range are compared and discussed. These methods all use an ultrafine condensation particle counter (TSI Inc. Model 3025 or its prototype) as the detector, but use different approaches to determine the size of the particles counted. Size classification was achieved using a Hauke Model VIE-06 differential

A. Wiedensohler; P. Aalto; D. Covert; J. Heintzenberg; P. H. McMurry

1994-01-01

285

Modelling detonation in ultrafine tatb hemispherical boosters using crest  

NASA Astrophysics Data System (ADS)

Hemispherical ultrafine TATB boosters can initiate detonation in the TATB-based explosive LX-17. For accurate hydrocode predictions of experiments using this combination of explosives, it is important to accurately model the detonation wave emerging from the booster material since this may influence the detonation behaviour in the main charge. Since ultrafine TATB exhibits non-ideal detonation behaviour, its response should be modelled using reactive flow. In this paper, the CREST reactive burn model, which uses entropy-dependent reaction rates to simulate explosive behaviour, is applied to LLNL experimental data obtained from ultrafine TATB hemispherical boosters initiated by slapper detonators at three initial temperatures (ambient, -20°C, and -54°C). The ambient temperature data is used to develop an initial CREST model for ultrafine TATB which is then subsequently applied to the cold data. A comparison of the experimental and modelling results is presented showing that the model gives good agreement to experiment at both ambient and cold temperatures

Whitworth, Nicholas J.

2012-03-01

286

Flocculation, hydrophobic agglomeration and filtration of ultrafine coal  

NASA Astrophysics Data System (ADS)

In coal preparation plant circuits, fine coal particles are aggregated either by oil agglomeration or by flocculation. In a new hydrophobic agglomeration process, recently developed hydrophobic latices are utilized. While the selectivity of such aggregation processes determines the beneficiation results, the degree of aggregation has a strong effect on fine coal filtration. The aim of this research was to study the fundamentals and analyze the common grounds for these processes, including the potential effect of the coal surface properties. The selective flocculation tests, in which three types of coal, which differed widely in surface wettability, and three additives (hydrophobic latices, a semi-hydrophobic flocculant and a typical hydrophilic polyelectrolyte) were utilized, showed that coal wettability plays a very important role in selective flocculation. The abstraction of a hydrophobic latex on coal and silica revealed that the latex had a much higher affinity towards hydrophobic coal than to hydrophilic mineral matter. As a result, the UBC-1 hydrophobic latex flocculated only hydrophobic coal particles while the polyelectrolyte (PAM) flocculated all the tested coal samples and minerals, showing no selectivity in the fine coal beneficiation. The oil agglomeration was tested using kerosene emulsified with various surfactants (e.g. cationic, anionic and non-ionic). Surfactants enhance not only oil emulsification, hence reducing oil consumption (down to 0.25--0.5%), but also entirely change the electrokinetic properties of the droplets and affect the interaction energy between oil droplets and coal particles. Consequently, the results found in the course of the experimental work strongly indicate that even oxidized coals can be agglomerated if cationic surfactants are used to emulsify the oil. Oil agglomeration of the Ford-4 ultrafine coal showed that even at extremely low oil consumption (0.25 to 0.5%), a clean coal product with an ash content around 5% at over 99.9% coal recovery could be obtained in a one-stage separation by screening the agglomerated product. If a conventional oil agglomeration process is used instead, oil consumption as high as 30% is needed to obtain comparable results. In the tests on filtration and dewatering of ultrafine and fine coals, the effect of chemical additives and coal surface properties was investigated. The tests revealed very significant differences in the filtration of ultrafine (-45 mum) and fine (-500 mum) coals. The moisture contents in the filter cakes in the tests with ultrafine coal were around 40% (irrespective of the coal surface properties), while for the fine coal the moisture content fluctuated around 18% (Ford-4) and 30% (Ford-13). The results revealed that the hydrophobic latex and the emulsified oils could not only successfully beneficiate the ultrafine coal but also significantly increase filtration rate and/or reduce moisture content of the filter cake. Among the chemicals tested, the emulsified oils were found to be the most promising not only for the beneficiation but also for filtration and dewatering processes. Surfactants were found to only slightly affect the filtration of fine coal. However, they can influence filtration very profoundly if utilized to emulsify the oil which is used to agglomerate coal prior to its filtration.

Yu, Zhimin

287

Fine and ultrafine particles at a near-free tropospheric environment over the high-altitude station Hanle in the Trans-Himalaya: New particle formation and size distribution  

Microsoft Academic Search

Number-size distributions of ultrafine, fine, and accumulation mode aerosols in the size range 5-1300 nm have been measured regularly from the pristine, high-altitude (for 4520 m above mean sea level) station Hanle in the Trans-Himalaya during the summer and autumn (August-November) 2009. The total number concentration ranged from 80 to 8000 cm-3 with a mean value of 1150 cm-3. Examination

K. Krishna Moorthy; V. Sreekanth; Jai Prakash Chaubey; Mukunda M. Gogoi; S. Suresh Babu; Sobhan Kumar Kompalli; S. P. Bagare; Bhuvan C. Bhatt; Vinod K. Gaur; T. P. Prabhu; N. S. Singh

2011-01-01

288

Study of an ultrafine w-EDM technique  

NASA Astrophysics Data System (ADS)

A precision ultrafine w-EDM (wire electrical discharge machining) technique specifically for machining intricate parts and structures is developed in this paper. A thumb-sized and versatile w-EDM device equipped with a complete control system for wire tension (ultrafine tungsten wire of 13 µm diameter) is designed and employed for the study of ultrafine w-EDM. The tension of the wire electrode is controlled by magnetic repulsive force to steady the wire during machining. Ultrafine wire cutting can be conducted in vertical-, horizontal- or slantwise-wire arrangements. Via some experiments, optimal machining conditions including discharge capacitance, feed rate, wire tension and the appropriate design for the w-EDM device are obtained. Two miniature samples including a micro of Taipei's landmark 101 building and a micro relay are fabricated and the feasibility of the proposed approach is verified. It is confirmed that the ultrafine w-EDM technique using an ultrafine tungsten wire of 13 µm was realized successfully.

Chen, Shun-Tong; Yang, Hong-Ye; Du, Chih-Wei

2009-11-01

289

Preliminary Attempt at Sintering an Ultrafine Alumina Powder Using Microwaves.  

National Technical Information Service (NTIS)

A commercially available microwave oven was used to sinter ultrafine alumina powders (0.02 -0.05 micrometers particle size) with and without CaO sintering aid. The oven was modified by inserting a thermocouple probe through the bottom housing, and thoroug...

E. M. Alhambra

1994-01-01

290

Heterogeneities in inflammatory and cytotoxic responses of RAW 264.7 macrophage cell line to urban air coarse, fine, and ultrafine particles from six European sampling campaigns  

SciTech Connect

We investigated the cytotoxic and inflammatory activities of size-segregated particulate samples (particulate matter, PM) from contrasting air pollution situations in Europe. Coarse (PM10-2.5), fine (PM2.5-0.2), and ultrafine (PM0.2) particulate samples were collected with a modified Harvard high-volume cascade impactor (HVCI). Mouse RAW 264.7 macrophages were exposed to the samples for 24 h. Selected inflammatory mediators, nitric oxide (NO) and cytokines (tumor necrosis factor alpha (TNF alpha), interleukin 6 (IL-6), macrophage inflammatory protein-2 (MIP-2)), were measured together with cytotoxicity (MTT test), and analysis of apoptosis and cell cycle (propidium iodide staining). The PM10-2.5 samples had a much higher inflammatory activity than the PM2.5-0.2 and PM0.2 samples, but the PM2.5-0.2 samples showed the largest differences in inflammatory activity, and the PM0.2 samples in cytotoxicity, between the sampling campaigns. The PM2.5-0.2 samples from traffic environments in springtime Barcelona and summertime Athens had the highest inflammatory activities, which may be related to the high photochemical activity in the atmosphere during the sampling campaigns. The PM0.2 sample from wintertime Prague with proven impacts from local coal and biomass combustion had very high cytotoxic and apoptotic activities and caused a distinct cell cycle arrest. Thus, particulate size, sources, and atmospheric transformation processes affect the toxicity profile of urban air particulate matter. These factors may explain some of the heterogeneity observed in particulate exposure-response relationships of human health effects in epidemiological studies.

Jalava, P.I.; Salonen, R.O.; Pennanen, A.S.; Sillanpaa, M.; Halinen, A.I.; Happo, M.S.; Hillamo, R.; Brunekreef, B.; Katsouyanni, K.; Sunyer, J.; Hirvonen, M.R. [National Public Health Institute, Kuopio (Finland). Dept. for Environmental Health

2007-03-15

291

SPLAT II: An Aircraft Compatible, Ultra-Sensitive, High Precision Instrument for In-Situ Characterization of the Size and Composition of Fine and Ultrafine Particles  

SciTech Connect

The properties of aerosols depend on the size and internal compositions of the individual particles. The vast majority of atmospheric aerosols are smaller than 200 nm, yet the single particle mass spectrometers, the only instruments that can characterize the size and internal compositions of individual particles, typically detect these small particles with extremely low efficiencies. In this paper we describe a new instrument called SPLAT II that provides unparalleled sensitivity to small particles, detecting 100% of particles that are larger than 125 nm and 40% of 100 nm particles. This instrument also brings an increase by a factor of 10 in temporal resolution, sizing up to 500 particles per second and characterizing the composition of up to 100 of them. SPLAT II uses a two-laser, two-step process to evaporate the particles and generate ions, producing high quality, reproducible mass spectra of the refractive and non-refractive aerosol fractions to yield the complete compositions of individual particles. The instrument control board provides for size dependent delays for lasers’ triggers to eliminate a size dependent hit rate. The mass spectra are recorded with 14-bit vertical resolution and analyzed using custom software packages. The instrument’s high sizing resolution and sensitivity makes it possible to combine it with the differential mobility analyzer(s) and measure particle size, composition, density, dynamic shape factor, hygroscopicity, and fractal dimension.

Zelenyuk, Alla; Yang, Juan; Choi, Eric Y.; Imre, Dan G.

2009-05-01

292

A comparative investigation of ultrafine particle number and mass emissions from a fleet of on-road diesel and CNG buses.  

PubMed

Particle number, particle mass, and CO2 concentrations were measured on the curb of a busy urban busway used entirely by a mix of diesel and CNG operated buses. With the passage of each bus, the ratio of particle number concentration and particle mass concentration to CO2 concentration in the diluted exhaust plume were used as measures of the particle number and mass emission factors, respectively. With all buses accelerating pastthe monitoring point, the results showed that the median particle mass emission from CNG buses was less than 9% of that from diesel buses. However, the median particle number emission from CNG buses was 6 times higher than the diesel buses, and the particles from the CNG buses were mainly in the nanoparticle size range. Using a thermodenuder to remove the volatile material from the sampled emissions showed that the majority of particles from the CNG buses, but not from the diesel buses, were volatile. Approximately, 82% of the particles from the CNG buses and 38% from the diesel buses were removed by heating the emissions to 300 degrees C. PMID:18800557

Jayaratne, E R; He, C; Ristovski, Z D; Morawska, L; Johnson, G R

2008-09-01

293

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 II: FIELD EVALUATION. (R827352C001)  

EPA Science Inventory

This study presents results from a field evaluation of a mobile versatile aerosol concentration enrichment system (VACES), designed to enhance the ambient concentrations of ultrafine (less than 0.18 ...

294

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 II. FIELD EVALUATION. (R826232)  

EPA Science Inventory

Abstract This study presents results from a field evaluation of a mobile versatile aerosol concentration enrichment system (VACES), designed to enhance the ambient concentrations of ultrafine (less than 0.18 ...

295

Effect of central fans and in-duct filters on deposition rates of ultrafine and fine particles in an occupied townhouse  

Microsoft Academic Search

Airborne particles are implicated in morbidity and mortality of certain high-risk subpopulations. Exposure to particles occurs mostly indoors, where a main removal mechanism is deposition to surfaces. Deposition can be affected by the use of forced-air circulation through ducts or by air filters. In this study, we calculate the deposition rates of particles in an occupied house due to forced-air

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

2004-01-01

296

A new process to fabricate ultrafine-grained low-carbon steel with high strength and high elongation  

Microsoft Academic Search

A new process to fabricate ultrafine-grained low-carbon steel was proposed. Low-carbon steel plates were intercritically quenched to obtain martensite–ferrite structure, and then warmly rolled at 700°C. The processed samples revealed bimodal ultrafine ferritic grains and nanoscale carbide particles, and showed excellent mechanical properties.

W. Lei; T. S. Wang; Z. Li; X. J. Zhang; Q. F. Wang; F. C. Zhang

2010-01-01

297

Flow and compaction behaviour of ultrafine coated ibuprofen.  

PubMed

Good flow and compaction properties are prerequisites for successful compaction process. Apart from initial profile, mechanical properties of pharmaceutical powders can get modified during unit processes like milling. Milled powders can exhibit a wide range of particle size distribution. Further downstream processing steps like compaction can be affected by this differential particle size distribution. This has greatest implications for formulations like high dose drugs wherein the active pharmaceutical ingredient (API) contributes the maximum bulk in the final formulation. The present study assesses the impact of dry coating with ultrafine particles of same material, on the flow and compaction properties of the core material. Ibuprofen was selected as model drug as it has been reported to have poor mechanical properties. Ultrafine ibuprofen (average size 1.75 ?m) was generated by Dyno(®) milling and was dry coated onto the core ibuprofen particles (average size 180 ?m). Compaction studies were performed using a fully instrumented rotary tablet press. Compaction data was analyzed for compressibility, tabletability, compactibility profiles and Heckel plot. Dry coating of the ibuprofen exhibited greater compressibility and tabletability, at lower compaction pressure. However, at compaction pressure above 220 MPa, compressibility and tabletability of coated as well as uncoated materials were found to be similar. Heckel analysis also supported the above findings, as P(y) value of uncoated ibuprofen was found to be 229.49 MPa and for 2.0% ultrafine coated ibuprofen was found to be 158.53 MPa. Lower P(y) value of ultrafine coated ibuprofen indicated ease of plastic deformation. Superior compressibility and deformation behaviour of ultrafine coated ibuprofen attributed to increased interparticulate bonding area. This strategy can also be explored for improving tabletability of high dose poorly compressible drugs. PMID:23142495

More, Parth K; Khomane, Kailas S; Bansal, Arvind K

2012-11-08

298

Ambient Particulate Pollutants in the Ultrafine Range Promote Early Atherosclerosis and Systemic Oxidative Stress  

PubMed Central

Air pollution is associated with significant adverse health effects, including increased cardiovascular morbidity and mortality. Exposure to particulate matter with an aerodynamic diameter of <2.5 ?m (PM2.5) increases ischemic cardiovascular events and promotes atherosclerosis. Moreover, there is increasing evidence that the smallest pollutant particles pose the greatest danger because of their high content of organic chemicals and prooxidative potential. To test this hypothesis, we compared the proatherogenic effects of ambient particles of <0.18 ?m (ultrafine particles) with particles of <2.5 ?m in genetically susceptible (apolipoprotein E–deficient) mice. These animals were exposed to concentrated ultrafine particles, concentrated particles of <2.5 ?m, or filtered air in a mobile animal facility close to a Los Angeles freeway. Ultrafine particle–exposed mice exhibited significantly larger early atherosclerotic lesions than mice exposed to PM2.5 or filtered air. Exposure to ultrafine particles also resulted in an inhibition of the antiinflammatory capacity of plasma high-density lipoprotein and greater systemic oxidative stress as evidenced by a significant increase in hepatic malondialdehyde levels and upregulation of Nrf2-regulated antioxidant genes. We conclude that ultrafine particles concentrate the proatherogenic effects of ambient PM and may constitute a significant cardiovascular risk factor.

Araujo, Jesus A.; Barajas, Berenice; Kleinman, Michael; Wang, Xuping; Bennett, Brian J.; Gong, Ke Wei; Navab, Mohamad; Harkema, Jack; Sioutas, Constantinos; Lusis, Aldons J.; Nel, Andre E.

2010-01-01

299

A novel technique for evaluating cleaned fine and ultrafine coal. Technical report, 1 December 1991--29 February 1992  

SciTech Connect

The purpose of this study is to develop a washability analysis system for fine and ultrafine coal particles using Density Gradient Centrifugation (DGC) and Thermal Gravimetric Analysis (TGA) techniques. The unique advantages of this proposed technique is that it provides a means to obtain usable washability curves on fine and ultrafine coal samples. The DGC technique will produce a large number of density fractions in a single run and, thus, is much faster and more efficient than normal washability analysis. During this quarter all of the samples to be used in this study have been received and reduced to the required size ranges. The set of 48 samples of IBCSP 101 have been separated by the DGC technique and submitted for moisture, ash and sulfur analysis.

Crelling, J.C.; Hippo, E.J.

1992-08-01

300

In-vehicle measurement of ultrafine particles on compressed natural gas, conventional diesel, and oxidation-catalyst diesel heavy-duty transit buses.  

PubMed

Many metropolitan transit authorities are considering upgrading transit bus fleets to decrease ambient criteria pollutant levels. Advancements in engine and fuel technology have lead to a generation of lower-emission buses in a variety of fuel types. Dynamometer tests show substantial reductions in particulate mass emissions for younger buses (<10 years) over older models, but particle number reduction has not been verified in the research. Recent studies suggest that particle number is a more important factor than particle mass in determining health effects. In-vehicle particle number concentration measurements on conventional diesel, oxidation-catalyst diesel and compressed natural gas transit buses are compared to estimate relative in-vehicle particulate exposures. Two primary consistencies are observed from the data: the CNG buses have average particle count concentrations near the average concentrations for the oxidation-catalyst diesel buses, and the conventional diesel buses have average particle count concentrations approximately three to four times greater than the CNG buses. Particle number concentrations are also noticeably affected by bus idling behavior and ventilation options, such as, window position and air conditioning. PMID:17219245

Hammond, Davyda; Jones, Steven; Lalor, Melinda

2007-02-01

301

High-temperature LDV seed particle development  

NASA Astrophysics Data System (ADS)

The feasibility of developing a method for making monodisperse, unagglomerated spherical particles greater than 50 nm in diameter was demonstrated. Carbonaceous particles were made by pyrolyzing ethylene with a pulsed CO2 laser, thereby creating a non-equilibrium mixture of carbon, hydrogen, hydrocarbon vapors, and unpyrolyzed ethylene. Via a complex series of reactions, the carbon and hydrocarbon vapors quickly condensed into the spherical particles. By cooling and dispersing them in a supersonic expansion immediately after their creation, the hot newly-formed spheres were prevented from colliding and coalescing, thus preventing the problem of agglomeration which as plagued other investigators studying laser-simulated particle formation. The cold particles could be left suspended in the residual gases indefinitely without agglomerating. Their uniform sizes and unagglomerated nature were visualized by collecting the particles on filters that were subsequently examined using electron microscopy. It was found the mean particle size can be coarsely controlled by varying the initial ethylene pressure, and can be finely controlled by varying the fluence (energy/unit area) with which the laser irradiates the gas. The motivating application for this research was to manufacture particles that could be used as laser Doppler velocimetry (LDV) seeds in high-temperature high-speed flows. Though the particles made in this program will not evaporate until heated to about 3000 K, and thus could serve as LDV seeds in some applications, they are not ideal when the hot atmosphere is also oxidizing. In that situation, ceramic materials would be preferable. Research performed elsewhere has demonstrated that selected ceramic materials can be manufactured by laser pyrolysis of appropriate supply gases. It is anticipated that, when the same gases are used in conjunction with the rapid cooling technique, unagglomerated spherical ceramic particles can be made with little difficulty. Such particles would also be valuable to manufacturers of ceramic or abrasive products, and this technique may find its greatest commercial potential in those areas.

Frish, Michael B.; Pierce, Vicky G.

1989-05-01

302

Intercomparison of four methods to determine size distributions of low-concentration (approximately 100 cm[sup [minus]3]), ultrafine aerosols (3 < D[sub p] < 10 nm) with illustrative data from the Arctic  

Microsoft Academic Search

Four different methods for measuring ultrafine particle size distributions in the 3-10-nm particle diameter range are compared and discussed. These methods all use an ultrafine condensation particle counter (TSI Inc. Model 3025 or its prototype) as the detector, but use different approaches to determine the size of the particles counted. Size classification was achieved using a Hauke Model VIE-06 differential

A. Wiedensohler; P. Aalto; D. Covert; J. Heintzenberg; P. H. McMurry

1994-01-01

303

Reactivity of layered vanadium pentoxide hydrate with ultrafine metal oxide, TiO2 and ZrO2, particles in an aqueous system  

Microsoft Academic Search

The interactions between vanadium pentoxide hydrate (V2O5·nH2O) sol and colloid solutions of ultra fine titanium dioxide TiO2 and zirconium dioxide particles ZrO2 were studied. When mixed with an intrinsic V2O5·nnH2O sol, TiO2 particles in the mixed sol are sandwiched by V2O5·nH2O layer sheets to form intercalation compounds. An Interlayer distance of V2O5·nH2O was increased by this treatment and the surface

S. Kittaka; K. Matsuno; K. Tanaka; Y. Kuroda; M. Fukuhara

2001-01-01

304

The preparation of ultrafine V 8C 7 powder and its phase reactions  

Microsoft Academic Search

The conventional carbothermal synthesis of V8C7 powder has weak points such as high reaction temperature and large particle size. This paper discusses the preparation of ultrafine V8C7 powder by reducing and carburizing the vanadium oxides using the carbon which is pyrolyzed from the organic compounds and the phase reactions during the preparation of ultrafine V8C7 powder. V2O5 dissolves in a

Lianwu Yan; Enxi Wu

2007-01-01

305

Development of an Ultrafine Coal Dewatering Technology and an Integrated Flotation-Dewatering System for Coal Preparation Plants  

Microsoft Academic Search

The project proposal was approved for only the phase I period. The goal for this Phase I project was to develop an industrial model that can perform continuous and efficient dewatering of fine coal slurries of the previous flotation process to fine coal cake of 15% water content from 50-70%. The feasibility of this model should be demonstrated experimentally using

Wu Zhang; David Yang; Amar Amarnath; Iftikhar Huq; Scott OBrien; Jim Williams

2006-01-01

306

In-vehicle Measurement of Ultrafine Particles on Compressed Natural Gas, Conventional Diesel, and Oxidation-catalyst Diesel Heavy-duty Transit Buses  

Microsoft Academic Search

Many metropolitan transit authorities are considering upgrading transit bus fleets to decrease ambient criteria pollutant\\u000a levels. Advancements in engine and fuel technology have lead to a generation of lower-emission buses in a variety of fuel\\u000a types. Dynamometer tests show substantial reductions in particulate mass emissions for younger buses (<10 years) over older\\u000a models, but particle number reduction has not been

Davyda Hammond; Steven Jones; Melinda Lalor

2007-01-01

307

New particle formation and ultrafine charged aerosol climatology at a high altitude site in the Alps (Jungfraujoch, 3580 m a.s.l., Switzerland)  

Microsoft Academic Search

We investigate the formation and growth of charged aerosols clusters at Jungfraujoch, in the Swiss Alps (3580 m a.s.l.), the highest altitude site of the European EUCAARI project intensive campaign. Charged particles and clusters (0.5-1.8 nm) were measured from April 2008 to April 2009 and allowed the detection of nucleation events in this very specific environment (presence of free tropospheric

J. Boulon; K. Sellegri; H. Venzac; D. Picard; E. Weingartner; G. Wehrle; M. Collaud Coen; R. Bütikofer; E. Flückiger; U. Baltensperger; P. Laj

2010-01-01

308

Ultra-fine coal characterization  

SciTech Connect

Research continued on this program to relate beneficiation characteristics of ultra-fine coals to the mineral-matter liberation and bulk properties of the coals. Washability tests are reported here which quantify mineral-matter liberation during ultra-fine grinding of Pittsburgh, Pocahontas No. 3, Sunnyside, Anderson and Beulah-Zap coals. The first three are bituminous coals from Pennsylvania, West Virginia and Utah, respectively, and the last two are a subbituminous coal from the Powder River area of Wyoming and a lignite coal from North Dakota. 4 refs., 5 tabs.

Smit, F.J.

1988-02-29

309

Some recent developments in particle detectors.  

NASA Astrophysics Data System (ADS)

Amongst the recent developments in particle detectors, the emphasis is on those based on the detection of ultraviolet or vacuum ultraviolet photons. The combination of wire chambers and photoionizable vapours, or photocathodes obtained by the condensation of such vapours, permits the building of a new class of Ring-Imaging Cherenkov detectors and BaF2 calorimeters.

Charpak, G.

1983-08-01

310

The response of a co-culture lung model to fine and ultrafine particles of incinerator fly ash at the air-liquid interface.  

PubMed

Elevated concentrations of particulate matter in the environmental atmosphere constitute a potential risk to human health. In vitro cell-based assays are therefore necessary to evaluate the toxicological potential of inhaled particulate emissions. In this study, the exposure of a co-culture cell model at the air-liquid interface was used to evaluate the dose-dependent biological effects of a test aerosol. The CULTEX system was used to expose human cells to an environmentally-relevant aerosol, generated from fly ash collected in a commercial municipal waste incinerator and resuspended in filtered air. Human bronchial epithelial cells, BEAS-2B, co-cultured with differentiated THP-1 macrophages growing on Transwell inserts, were employed in the bioassay. Analyses of cell viability, interleukin-8 (IL-8) release, intracellular glutathione, and haeme oxygenase-1 enzyme expression were performed. Transportation of the cells and exposure to humidified filtered air or the test aerosol, at 100 ml/min for 1 to 6 hours, were well tolerated by the cells and had no effect on their viability. Levels of IL-8 release and haeme oxygenase-1 expression were elevated by exposure to fly ash aerosol as a function of time, but not by exposure to clean air. For IL-8 release, a dose-dependent effect was demonstrated with the assumption that the deposited mass of the particles correlated with exposure time. Exposure to the test aerosol did not affect the intracellular glutathione concentration. This in vitro approach simulates particle deposition in the human lung more realistically than does submerged exposure, and it preserves the inherent properties of the particles. It shows promise for use to detect particulate emissions which are potentially detrimental to human health. PMID:18662093

Diabaté, Silvia; Mülhopt, Sonja; Paur, Hanns-Rudolf; Krug, Harald F

2008-07-01

311

Synthesis, characterization, and microstructural evolution of ultrafine oxide powders  

NASA Astrophysics Data System (ADS)

Phase-pure, homogeneous, single- and multi-component ultrafine ceramic oxide particles (UFPs) were synthesized via flame spray pyrolysis (FSP) of combustible metalloorganic precursors. A variety of single source, atomically mixed, inexpensive, and air stable chemical precursors were used to (1) demonstrate the versatility of FSP to produce high purity UFPs and (2) control their phase and composition. Ultrafine TiOsb2,\\ CeOsb2,\\ 3Alsb2Osb3{*}2SiOsb2 (mullite), and Ysb3Alsb5Osb{12} (YAG) composition powders were produced by injecting a metalloorganic precursor/ethanol solution into a flame. UFP production occurs by combustion of the aerosol droplets of this solution to produce molecular M-O monomers, which then coalesce to form molecular clusters, which in turn form larger particles. These particles then grow via vapor condensation and/or coagulation. The semi-continuous FSP process used 50-100 mL of precursor/min to produce powders at 300-500 g/h. The resulting UFPs were characterized with gas sorption, CHN, TGA, DTA, DRIFTS, XRD, and TEM techniques. Ultrafine TiOsb2 particle sizes were 40-60 nm with surface areas of 35 msp2/g and were mostly unagglomerated, single crystals. Mullite particles were mostly unagglomerated amorphous particles with some interparticle necking. Ultrafine mullite particle sizes ranged from 40-80 nm (due to necking) with surface areas = 45 msp2/g. Ultrafine CeOsb2 particles averaged 80 nm in diameter and were unagglomerated single crystals with surface areas = 10 msp2/g. The compaction and sintering behavior of UFPs were traced with XRD, DRIFTS, and SEM techniques. UFP compacts sinter and densify at lower temperatures than typical of coarser powder compacts. This work reports significant results for which there are no literature precedents. UFP-TiOsb2 densified to 97% of theory with final average grain sizes of $2 mum. CeOsb2 inherent oxygen vacancies render it thermally unstable above 800spcirc$C, where extensive grain growth occurs due to rapid oxygen diffusion. Doping may further inhibit grain growth in all compacts of UFP powders. Future work entails doping in the precursor state as well as solid-state doping.

Baranwal, Rita

312

Plasma synthesis and characterization of ultrafine SiC  

SciTech Connect

Ultrafine SiC powders have been prepared by gas phase synthesis from silane and methane in an argon thermal rf-plasma. Bulk properties of the powders were determined by elemental analysis, x-ray diffractin, helium pycnometry, and BET surface area measurements. The near-surface composition and structure of the particles were examined by x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). In addition to free silicon and carbon particles in the powders, free carbon and various silicon/carbon/oxygen species were found on the surface of the SiC particles.

Vogt, G.J.; Phillips, D.S.; Taylor, T.N.

1986-01-01

313

Contrast in air pollution components between major streets and background locations: Particulate matter mass, black carbon, elemental composition, nitrogen oxide and ultrafine particle number  

NASA Astrophysics Data System (ADS)

Policies to reduce outdoor air pollution concentrations are often assessed on the basis of the regulated pollutants. Whether these are the most appropriate components to assess the potential health benefits is questionable, as other health-relevant pollutants may be more strongly related to traffic. The aim of this study is to compare the contrast in concentration between major roads and (sub)urban background for a large range of pollutants and to analyze the magnitude of the measured difference in the street - background for major streets with different street configurations. Measurements of PM 10, PM 2.5, particle number concentrations (PNC), black carbon (BC), elemental composition of PM 10 and PM 2.5 and NO x were conducted simultaneously in eight major streets and nine (sub)urban background locations in the Netherlands. Measurements were done six times for a week during a six month period in 2008. High contrasts between busy streets and background locations in the same city were found for chromium, copper and iron (factor 2-3). These elements were especially present in the coarse fraction of PM. In addition, high contrasts were found for BC and NO x (factor 1.8), typically indicators of direct combustion emissions. The contrast for PNC was similar to BC. NO 2 contrast was lower (factor 1.5). The largest contrast was found for two street canyons and two streets with buildings at one side of the street only. The contrast between busy streets and urban background in NO 2 was less than the contrast found for BC, PNC and elements indicative of non-exhaust emissions, adding evidence that NO 2 is not representing (current) traffic well. The study supports a substantial role for non-exhaust emissions including brake- and tyre wear and road dust in addition to direct combustion emissions. Significant underestimation of disease burden may occur when relying too much on the regulated components.

Boogaard, Hanna; Kos, Gerard P. A.; Weijers, Ernie P.; Janssen, Nicole A. H.; Fischer, Paul H.; van der Zee, Saskia C.; de Hartog, Jeroen J.; Hoek, Gerard

2011-01-01

314

Synthesis of ultrafine particles of intermetallic compounds by the vapor-phase magnesium reduction of chloride mixtures: Part I. Titanium aluminides  

Microsoft Academic Search

A new chemical synthesis process for the preparation of intermetallic compounds has been developed. It involves the vapor-phase\\u000a reduction of mixtures of constituent metal chlorides by magnesium vapor to produce intermetallic compounds in the form of\\u000a fine powder. The advantages of the process include (a) the use of inexpensive raw materials, (b) low reaction temperatures,\\u000a and (c) products in the

H. Y. Sohn; S. Paldey

1998-01-01

315

Initial study of dry ultrafine coal beneficiation utilizing triboelectric charging with subsequent electrostatic separation.  

National Technical Information Service (NTIS)

A novel, dry process using electrostatics to beneficiate ultrafine coal is being developed by the Coal Preparation Division at the Pittsburgh Energy Technology Center. The historical concept of triboelectricity and its eventual use as a means of charging ...

T. A. Link R. P. Killmeyer R. H. Elstrodt N. H. Haden

1990-01-01

316

Cytocompatible and water stable ultrafine protein fibers for tissue engineering  

NASA Astrophysics Data System (ADS)

This dissertation proposal focuses on the development of cytocompatible and water stable protein ultrafine fibers for tissue engineering. The protein-based ultrafine fibers have the potential to be used for biomedicine, due to their biocompatibility, biodegradability, similarity to natural extracellular matrix (ECM) in physical structure and chemical composition, and superior adsorption properties due to their high surface to volume ratio. However, the current technologies to produce the protein-based ultrafine fibers for biomedical applications still have several problems. For instance, the current electrospinning and phase separation technologies generate scaffolds composed of densely compacted ultrafine fibers, and cells can spread just on the surface of the fiber bulk, and hardly penetrate into the inner sections of scaffolds. Thus, these scaffolds can merely emulate the ECM as a two dimensional basement membrane, but are difficult to mimic the three dimensional ECM stroma. Moreover, the protein-based ultrafine fibers do not possess sufficient water stability and strength for biomedical applications, and need modifications such as crosslinking. However, current crosslinking methods are either high in toxicity or low in crosslinking efficiency. To solve the problems mentioned above, zein, collagen, and gelatin were selected as the raw materials to represent plant proteins, animal proteins, and denatured proteins in this dissertation. A benign solvent system was developed specifically for the fabrication of collagen ultrafine fibers. In addition, the gelatin scaffolds with a loose fibrous structure, high cell-accessibility and cell viability were produced by a novel ultralow concentration phase separation method aiming to simulate the structure of three dimensional (3D) ECM stroma. Non-toxic crosslinking methods using citric acid as the crosslinker were also developed for electrospun or phase separated scaffolds from these three proteins, and proved to be efficient to enhance the strength and water stability of scaffolds. The crosslinked protein scaffolds showed higher cytocompatibility than the polylactic acid scaffolds and the fibers crosslinked by glutaraldehyde. The potential of using these protein-based ultrafine fibers crosslinked by citric acid for tissue engineering has been proved in this dissertation.

Jiang, Qiuran

317

Modeling Detonation in Ultrafine TATB Hemispherical Boosters Using CREST  

NASA Astrophysics Data System (ADS)

Hemispherical ultrafine TATB boosters are often used to initiate detonation in the TATB-based explosive LX-17. For accurate hydrocode predictions of experiments using this combination of explosives, it is important to accurately model the detonation wave emerging from the booster material since this may influence the detonation behaviour in the main charge. Since ultrafine TATB exhibits non-ideal detonation behaviour, it's response should be modeled using reactive flow. In this paper, the CREST reactive burn model, which uses entropy- dependent reaction rates to simulate explosive behaviour, is applied to experimental data obtained from ultrafine TATB hemispherical boosters initiated by slapper detonators at three initial temperatures (ambient, -20 degC and -54 degC). The ambient temperature data is used to develop an initial CREST model for ultrafine TATB which is then subsequently applied to the cold data. A comparison of the experimental and modeling results is presented showing that the model gives good agreement to experiment at both ambient and cold temperatures.

Whitworth, Nicholas

2011-06-01

318

Preparation, characterization, and cytotoxicity of CPT/Fe2O3-embedded PLGA ultrafine composite fibers: a synergistic approach to develop promising anticancer material  

PubMed Central

The aim of this study was to fabricate camptothecin/iron(III) oxide (CPT/Fe2O3)-loaded poly(D,L-lactide-co-glycolide) (PLGA) composite mats to modulate the CPT release and to improve the structural integrity and antitumor activity of the released drug. The CPT/Fe2O3-loaded PLGA ultrafine fibers were prepared for the first time by electrospinning a composite solution of CPT/Fe2O3 and neat PLGA (4 weight percent). The physicochemical characterization of the electrospun composite mat was carried out by scanning electron microscopy, energy dispersive X-ray spectroscopy, electron probe microanalysis, thermogravimetry, transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray diffraction pattern. The medicated composite fibers were evaluated for their cytotoxicity on C2C12 cells using Cell Counting Kit-8 assay (Sigma-Aldrich Corporation, St Louis, MO). The in vitro studies indicated a slow and prolonged release over a period of 96 hours with mild initial burst. Scanning electron microscopy, thermogravimetry, and X-ray diffraction studies confirmed the interaction of CPT/Fe2O3 with the PLGA matrix and showed that the crystallinity of CPT decreased after loading. Incorporation of CPT in the polymer media affected both the morphology and the size of the CPT/Fe2O3-loaded PLGA composite fibers. Electron probe microanalysis and energy dispersive X-ray spectroscopy results confirmed well-oriented composite ultrafine fibers with good incorporation of CPT/Fe2O3. The cytotoxicity results illustrate that the pristine PLGA did not exhibit noteworthy cytotoxicity; conversely, the CPT/Fe2O3 composite fibers inhibited C2C12 cells significantly. Thus, the current work demonstrates that the CPT/Fe2O3-loaded PLGA composite fibers represent a promising chemotherapeutic system for enhancing anticancer drug efficacy and selectively targeting cancer cells in order to treat diverse cancers.

Amna, Touseef; Hassan, M Shamshi; Nam, Ki-Taek; Bing, Yang You; Barakat, Nasser AM; Khil, Myung-Seob; Kim, Hak Yong

2012-01-01

319

Size distributions of fine and ultrafine particles in the city of Strasbourg: correlation between number of particles and concentrations of NO(x) and SO(2) gases and some soluble ions concentration determination.  

PubMed

An Electrical Low Pressure Impactor (ELPI) was used during spring and autumn 2003 in the centre of Strasbourg for the measurement of atmospheric aerosols size distribution. The concentration of NO(x) and SO(2) in air was simultaneously measured with specific analysers. Samples were collected in the range 0.007-10 microm in equivalent aerodynamic diameter size. Number distributions are representative of a pollution originating from urban traffic with a particle size distribution exhibiting a nucleation mode below 29 nm and an accumulation mode around 80 nm in size. A mean particle density equal to 39000+/-35000 total particles per cm(3) with a size ranging from 7 to 10 microm was obtained after a sampling period of 2 weeks in spring. About 86.9% of the number of particles have an aerodynamic diameter below 0.1 microm and 13.1% between 0.1 and 1 microm. Correlation coefficients between the number of particles impacted on each ELPI plate and gas concentrations (SO(2) and NO(x)) showed that the numbers of particles with diameter between 0.10 and 0.62 microm are highly related to the NO(x) concentration. This result indicates that particles are traffic induced since NO(x) is mainly emitted by cars as shown by measurements on various sites. Particles are less clearly correlated to the SO(2) concentration. Particle analysis on different ELPI plates for a sampling period of 2 weeks in autumn showed high level of soluble NO(3)(-), SO(4)(2-) and NH(4)(+) ions. Indeed, up to 90% b.w. of these three species were found in the particle range 0.1-1 microm. The formation of particulate NH(4)NO(3) is favoured by high NO(x) concentration, which induces the formation of gaseous HNO(3). PMID:17275982

Roth, Estelle; Kehrli, Damaris; Bonnot, Karine; Trouvé, Gwénaëlle

2007-02-02

320

Evaluating measurements of new particle concentrations, source rates, and spatial scales during coastal nucleation events using condensation particle counters  

Microsoft Academic Search

Condensation particle counters (CPCs), used to examine particle production in the coastal environment, are evaluated for their ability to differentiate ultrafine sizes between 3 and 10 nm, along with their ability to count high total particle number concentrations encountered during coastal nucleation events. Four ultrafine particles counters, with a 3 nm detection limit, were deployed in a spatial array comprising

K. Hämeri; C. D. O'Dowd; C. Hoell

2002-01-01

321

Future Particle Accelerator Developments for Radiation Therapy  

NASA Astrophysics Data System (ADS)

During the last decade particle beam cancer therapy has seen a rapid increase in interest, and several new centers have been built, are currently under construction, or are in an advanced stage of planning. Typical treatment centers today consist of an accelerator capable of producing proton or ion beams in an energy range of interest for medical treatment, i.e. providing a penetration depth in water of about 30 cm, a beam delivery system to transport the produced beam to the patient treatment rooms, and several patient stations, allowing for an optimal usage of the continuously produced beam. This makes these centers rather large and consequently expensive. Only major hospital centers situated in an area where they can draw on a population of several million can afford such an installation. In order to spread the use of particle beam cancer therapy to a broader population base it will be necessary to scale down the facility size and cost. This can in principle be done by reducing the number of treatment rooms to one, eliminating the need of an elaborate beam delivery system, and thereby reducing the building size and cost. Such a change should be going in parallel with a reduction of the accelerator itself, and a number of approaches to this are currently being pursued. If successful, such developments could eventually lead to a compact system where all components would fit into a single shielded room, not much different in size from a typical radiation vault for radiotherapy with X-rays.

Holzscheiter, Michael H.; Bassler, Niels

322

Ultrafine hydrogen storage powders  

DOEpatents

A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

Anderson, Iver E. (Ames, IA); Ellis, Timothy W. (Doylestown, PA); Pecharsky, Vitalij K. (Ames, IA); Ting, Jason (Ames, IA); Terpstra, Robert (Ames, IA); Bowman, Robert C. (La Mesa, CA); Witham, Charles K. (Pasadena, CA); Fultz, Brent T. (Pasadena, CA); Bugga, Ratnakumar V. (Arcadia, CA)

2000-06-13

323

Influence of the sampling site, the season of the year, the particle size and the number of nucleation events on the chemical composition of atmospheric ultrafine and total suspended particles  

NASA Astrophysics Data System (ADS)

Twenty one organic compounds including three monocarboxylic and ten dicarboxylic acids, four aldehydes, three polyols and one amine were determined in 61 atmospheric aerosol particle samples with different sizes (30 ± 4-nm, 40 ± 5-nm, 50 ± 5-nm and total suspended particles) collected at two sampling sites, the SMEAR II and SMEAR III stations during different seasons of the year. Non supervised pattern recognition techniques, such as hierarchical cluster analysis and principal component analysis were used to study the influence of the collection place, the season of the year and the particle size on the concentration and behavior of the target compounds. The reliability of these results was proved using a supervised pattern recognition technique such as soft independent modeling of class analogy. The results achieved demonstrate that the chemical composition of the atmospheric aerosol particles is affected by the potential emission sources and the reactivity of the studied compounds under certain atmospheric conditions. In addition, from quantitative analysis methodologies partial least squares regression and principal component regression models were successfully used to clarify the influence of the number of nucleation events on the chemical composition of the particles.

Ruiz-Jimenez, Jose; Parshintsev, Jevgeni; Laitinen, Totti; Hartonen, Kari; Petäjä, Tuukka; Kulmala, Markku; Riekkola, Marja-Liisa

2012-03-01

324

Observations of turbulence-induced new particle formation in the residual layer  

NASA Astrophysics Data System (ADS)

Aerosol particle measurements in the atmospheric boundary layer performed by a helicopter-borne measurement payload and by a lidar system from a case study during the IMPACT field campaign in Cabauw (NL) are presented. Layers of increased number concentrations of ultrafine particles were observed in the residual layer, indicating relatively recent new-particle formation. These layers were characterized by a sub-critical Richardson number and concomitant increased turbulence. Turbulent mixing is likely to lead to local supersaturation of possible precursor gases which are essential for new particle formation. Observed peaks in the number concentrations of ultrafine particles at ground level are connected to the new particle formation in the residual layer by boundary layer development and vertical mixing.

Wehner, B.; Siebert, H.; Ansmann, A.; Ditas, F.; Seifert, P.; Stratmann, F.; Wiedensohler, A.; Apituley, A.; Shaw, R. A.; Manninen, H. E.; Kulmala, M.

2010-01-01

325

Observations of turbulence-induced new particle formation in the residual layer  

NASA Astrophysics Data System (ADS)

Aerosol particle measurements in the atmospheric boundary layer performed by a helicopter-borne measurement payload and by a lidar system from a case study during the IMPACT field campaign in Cabauw (NL) are presented. Layers of increased number concentrations of ultrafine particles were observed in the residual layer, indicating relatively recent new-particle formation. These layers were characterized by a sub-critical Richardson number and concomitant increased turbulence. Turbulent mixing is likely to lead to local supersaturation of possible precursor gases which are essential for new particle formation. Observed peaks in the number concentrations of ultrafine particles at ground level are connected to the new particle formation in the residual layer by boundary layer development and vertical mixing.

Wehner, B.; Siebert, H.; Ansmann, A.; Ditas, F.; Seifert, P.; Stratmann, F.; Wiedensohler, A.; Apituley, A.; Shaw, R. A.; Manninen, H. E.; Kulmala, M.

2010-05-01

326

Preliminary attempt at sintering an ultrafine alumina powder using microwaves. Master's thesis  

SciTech Connect

A commercially available microwave oven was used to sinter ultrafine alumina powders (0.02 - 0.05 micrometers particle size) with and without CaO sintering aid. The oven was modified by inserting a thermocouple probe through the bottom housing, and thoroughly insulating the interior with insulating material. The oven was placed in a glove box and filled with argon to prevent degradation of the thermocouple, and oxidation of the powdered graphite susceptor. Heating rates of 50-75 Deg C/sec with a maximum temperature of 1575 Deg C were obtained. Limited success in sintering of the the powder compacts was achieved in this preliminary effort. The microstructures of the sintered products were examined by scanning electron microscopy. It was concluded that further work is necessary to develop this technique into one which can be used for the routine sintering of fine powdered ceramic material. A review of the literature on microwave sintering of ceramic powders is also reported.

Alhambra, E.M.

1994-09-01

327

Effect of ultrafine zinc oxide (ZnO) nanoparticles on induction of oral tolerance in mice.  

PubMed

Ultrafine nanoparticles of zinc oxide (ZnO) recently became available as a substitute for larger-size fine ZnO particles. However, the biological activity of ultrafine ZnO currently remains undefined. In the present study, we investigated the effect of ultrafine ZnO on oral tolerance that plays an important role in the prevention of food allergy. Oral tolerance was induced in mice by a single oral administration (i.e., gavage) of 25 mg of ovalbumin (OVA) 5 days prior to a subcutaneous immunization with OVA (Day 0). Varying doses of ultrafine (diameter: approximately 21 nm) as well as fine (diameter: < 5 microm) ZnO particles were given orally at the same time during the OVA gavage. The results indicated that a single oral administration of OVA was followed by significant decreases in serum anti-OVA IgG, IgG(1), IgG(2a), and IgE antibodies and in the proliferative responses to the antigen by these hosts' spleen cells. The decreases in these immune responses to OVA were associated with a marked suppression of secretion of interferon (IFN)gamma, interleukin (IL)-5, and IL-17 by these lymphoid cells. Treatment with either ultrafine or fine ZnO failed to affect the oral OVA-induced suppression of antigen-specific IgG, IgG(1), IgG(2a), and IgE production or lymphoid cell proliferation. The suppression induced by the oral OVA upon secretion of IFN gamma, IL-5, and IL-17 was also unaffected by either size of ZnO. These results indicate that ultrafine particles of ZnO do not appear to modulate the induction of oral tolerance in mice. PMID:20507255

Matsumura, Misa; Takasu, Nobuo; Nagata, Masafumi; Nakamura, Kazuichi; Kawai, Motoyuki; Yoshino, Shin

328

Producing bulk ultrafine-grained materials by severe plastic deformation  

Microsoft Academic Search

This overview highlights very recent achievements and new trends in one of the most active and developing fields in modern\\u000a materials science: the production of bulk ultrafine-grained (UFG) materials using severe plastic deformation (SPD). The article\\u000a also summarizes the chronology of early work in SPD processing and presents clear and definitive descriptions of the terminology\\u000a currently in use in this

Ruslan Z. Valiev; Yuri Estrin; Zenji Horita; Terence G. Langdon; Michael J. Zechetbauer; Yuntian T. Zhu

2006-01-01

329

Preparation of ultrafine catalyst powders using a flow-through hydrothermal process  

Microsoft Academic Search

The rapid thermal decomposition of solutes (RTDS) process was used to produce ultrafine iron-bearing oxide and hydroxide powders for use as coal liquefaction catalysts. The RTDS process subjects aqueous solutions containing dissolved metal salts to elevated temperatures and pressures in a flow-through apparatus. Particle formation is initiated during brief exposure of the solution to a heated region, then is quenched

D. W. Matson; J. C. Linehan; J. G. Darab

1993-01-01

330

Redistribution of elements during heat treatment of alloy AK7 containing ultrafinely dispersed nitrides  

Microsoft Academic Search

(rn) where ahn is the molar volume of component m; n m is the density of component m, moles. In this work, with the aim of establishing the effect of ultrafinely dispersed titanium nitride particles on diffusion processes in aluminum alloys, a study was made of the redistribution of silicon, copper, magnesium, and iron in a diffusion pair in AK7

D. F. Chernega; V. G. Mogilatenko; L. V. Shepeleva

1991-01-01

331

The synthesis of ultrafine titanium nitride in an r.f. plasma  

Microsoft Academic Search

The ultrafine titanium nitride particles with a statistical median size of about 10 nm were prepared by passing pure titanium powder (2]\\/[Ti] molar ratio of the reactant on the nature of the products were investigated by chemical analysis, X-ray diffraction and electron microscopy. The conversion efficiency was close to 100%. The colour of the product was black, which is attributed

Toyonobu Yoshida; Akihisa Kawasaki; Kunihiko Nakagawa; Kazuo Akashi

1979-01-01

332

Nuclear microprobe investigation of the penetration of ultrafine zinc oxide into intact and tape-stripped human skin  

NASA Astrophysics Data System (ADS)

Ultrafine metal oxides, such as titanium dioxide and zinc oxide are widely used in cosmetic and health products like sunscreens. These oxides are potent UV filters and the small particle size makes the product more transparent compared to formulations containing coarser particles. In the present work the penetration of ultrafine zinc oxide into intact and tape-stripped human skin was investigated using nuclear microprobe techniques, such as proton induced X-ray spectroscopy and scanning transmission ion microscopy. Our results indicate that the penetration of ultrafine zinc oxide, in a hydrophobic basis gel with 48 h application time, is limited to the stratum corneum layer of the intact skin. Removing the stratum corneum partially or entirely by tape-stripping did not cause the penetration of the particles into the deeper dermal layers; the zinc particles remained on the surface of the skin.

Szikszai, Z.; Kertész, Zs.; Bodnár, E.; Major, I.; Borbíró, I.; Kiss, Á. Z.; Hunyadi, J.

2010-06-01

333

Ultrafine luminescent structures through nanoparticle self-assembly  

NASA Astrophysics Data System (ADS)

We report the fabrication of ultrafine structures consisting of regular arrays of nanoemitters through the self-assembly of luminescent nanoparticles on a silicon wafer. Nanoparticles of yttrium aluminium garnet (YAG) doped with Eu3+ ions were synthesized by a sonochemical technique. These particles, suspended in ethanol, are introduced onto a pre-patterned silicon wafer, covered with a thin oxide layer. On annealing the sample in an ultrahigh-vacuum chamber, the nanoparticles self-assemble along the pattern. We demonstrate this 'chemical lithography' by assembling the nanoparticles along a variety of patterns. We believe that such self-organized nanopatterning of functional structures is important for the realization of nanodevices.

Prabhakaran, K.; Götzinger, S.; Shafi, K. V. P. M.; Mazzei, A.; Schietinger, S.; Benson, O.

2006-08-01

334

Development and Performance of Charged Nano Particle Collector  

Microsoft Academic Search

Nucleation events have been observed at many sites worldwide, but the mechanism of the nucleation process is not clear - several hypotheses have been posed to explain these events. To obtain further insight into the chemical composition of these nano particles, a Nano Particle Collector (Nano PC) has been developed based the size dependence of particle mobility. We constructed a

Y. Zhao; A. S. Wexler

2005-01-01

335

Preparation of Ultrafine W-Cu Composite Powder Using Ultrasonic-Assisted Electroless Plating  

NASA Astrophysics Data System (ADS)

W-Cu ultrafine/nanocomposite powders have high sintering activity, so ultrafine/nanotechnology of W-Cu composite powders is one of the main methods to obtain fully dense, high-performance W-Cu composite materials. Cu-coated ultrafine W composite powders were synthesized by ultrasonic-assisted electroless plating process with non-noble metal activation pretreatment at room temperature in this paper. The growth mechanism of Cu layers and surface morphologies and composition of initial ultrafine W powders, pretreated W powders and Cu-coated W powders were analyzed by field emission scanning electron microscopy (FE-SEM), and energy dispersion spectrometry (EDS). The results show that the uniformly Cu coated W composite powder is successfully synthesized without conventional sensitization and activation steps by ultrasonic-assisted electroless plating at room temperature. The Cu layers on the ultrafine W powders had cell structure with dense, uniform distribution. The growth mechanism of Cu layers appears as follows: the surfaces of pretreated W powders appear linear-like and lamellar-like surface defects which act as activated sites. The reactants in the plating solution were adsorbed on catalytic activity surfaces of powders and happened oxidation-reduction reaction. The growth and aggregation mechanisms of Cu particles after nucleation are stripy Cu-cells grew up, bend, bifurcated, and aggregated, then wounding into a cellular structure, like "wrapping wool clusters" in the life. Finally, Cu cells grow up and merge into a layer.

Huang, Limei; Luo, Laima; Ding, Xiaoyu; Zan, Xiang; Hong, Yu; Cheng, Jigui; Wu, Yucheng; Luo, Guangnan; Zhu, Liu

2013-07-01

336

Development of Improved Magnetic Particle Inspection Procedures.  

National Technical Information Service (NTIS)

Current magnetic particle inspections for surface and near-surface flaws in ferromagnetic parts are dependent on human observations, decisions and errors. An improvement on this would be a semi-automatic device for detection and decision making that could...

E. F. Bauer

1971-01-01

337

Ultrafine-grained titanium for medical implants  

DOEpatents

We disclose ultrafine-grained titanium. A coarse-grained titanium billet is subjected to multiple extrusions through a preheated equal channel angular extrusion (ECAE) die, with billet rotation between subsequent extrusions. The resulting billet is cold processed by cold rolling and/or cold extrusion, with optional annealing. The resulting ultrafine-grained titanium has greatly improved mechanical properties and is used to make medical implants.

Zhu, Yuntian T. (Los Alamos, NM); Lowe, Terry C. (Santa Fe, NM); Valiev, Ruslan Z. (Ufa, RU); Stolyarov, Vladimir V. (Ufa, RU); Latysh, Vladimir V. (Ufa, RU); Raab, Georgy J. (Ufa, RU)

2002-01-01

338

Development of particle swarm optimization algorithm  

Microsoft Academic Search

Particle swarm optimization (PSO) is a new stochastic optimization technique based on swarm intelligence. In this paper, we introduce the basic principles of PSO firstly. Then, the research progress on PSO algorithm is summarized in several fields, such as parameter selection and design, population topology, hybrid PSO algorithm etc. Finally, some vital applications and aspects that may be conducted in

Yu Chen; Fan Yang; Quan Zou; Chen Lin

2011-01-01

339

Comparison of inhibitory activities of zinc oxide ultrafine and fine particulates on IgE-induced mast cell activation.  

PubMed

The effects of ultrafine and fine particles of zinc oxide (ZnO) on IgE-dependent mast cell activation were investigated. The rat mast cell line RBL2H3 sensitized with monoclonal anti-ovalbumin (OVA) IgE was challenged with OVA in the presence or absence of ZnO particles and zinc sulfate (ZnSO4). Degranulation of RBL2H3 was examined by the release of ?-hexosaminidase. To understand the mechanisms responsible for regulating mast cell functions, the effects of ZnO particles on the levels of intracellular Zn2+, Ca2+, phosphorylated-Akt, and global tyrosine phosphorylation were also measured. IgE-induced release of b-hexosaminidase was obviously attenuated by ultrafine ZnO particles and ZnSO4, whereas it was very weakly inhibited by fine ZnO particles. The intracellular Zn2+ concentration was higher in the cells incubated with ultrafine ZnO particles than in those with fine ZnO particles. Consistent with inhibitory effect on release of b-hexosaminidase, ultrafine ZnO particles and ZnSO4, but not fine ZnO particle, strongly attenuated the IgE-mediated increase of phosphorylated-Akt and tyrosine phosphorylations of 100 and 70 kDa proteins in RBL2H3 cells. These findings indicate that ultrafine ZnO particles, with a small diameter and a large total surface area/mass, could release Zn2+ easily and increase intracellular Zn2+ concentration efficiently, thus decreasing FceRI-mediated mast cell degranulation through inhibitions of PI3K and protein tyrosine kinase activation. Exposure to ZnO particles might affect immune responses, especially in allergic diseases. PMID:19609684

Yamaki, Kouya; Yoshino, Shin

2009-12-01

340

Effects of ultra-fine materials on workability and strength of concrete containing alkali-activated slag as the binder  

Microsoft Academic Search

This paper presents the results of an investigation into the effects of ultra-fine materials on workability and strength development of concrete containing alkali-activated slag (AAS) as the binder. It was found that partial replacement of slag with ultra-fine fly ash significantly improves the workability; however, the strength development is similar to ordinary portland cement (OPC). Partial replacement of slag with

Frank Collins; J. G Sanjayan

1999-01-01

341

Radio frequency (RF) suspension plasma sprayed ultra-fine hydroxyapatite (HA)\\/zirconia composite powders  

Microsoft Academic Search

Ultra-fine hydroxyapatite (HA)\\/ZrO2 composite powders was synthesised by radio frequency (RF) induction suspension plasma spray. A wet suspension of HA\\/ZrO2 was employed as feedstock. The suspension was injected axially into the RF plasma to produce the nano-composite powders, which were subsequently accumulated in cyclone collectors. The particle size and morphology was resolved by using the Zeta potential nano-particle size analyser,

Rajendra Kumar; P. Cheang; K. A. Khor

2003-01-01

342

Phase transformation of ultrafine rare earth oxide powders synthesized by radio frequency plasma spraying  

Microsoft Academic Search

Inductively coupled radio frequency plasma spraying was used to prepare ultrafine powders of Sm2O3, Dy2O3, and Lu2O3. These three materials were studied because they are effective dopants in multi-layer ceramic capacitors (MLCC) to improve lifetime. The as-sprayed powders consist of both micron-sized mono-dispersed spherical particles and nano-sized particles in various shapes. In addition to the spheroidization effect, plasma treatment leads

X. L. Sun; A. I. Y. Tok; R. Huebner; F. Y. C. Boey

2007-01-01

343

Vaporization--Condensation Generation of Ultrafine Hydrocarbon Particulate Matter for Inhalation Toxicology Studies  

Microsoft Academic Search

An evaporation\\/condensation particle generator produced 30-50 nm count median diameter particles from both pure hydrocarbons and from a complex mixture--used motor oil--at a concentration above 1 2 10 6 \\/cm 3 . The objective was to generate ultrafine aerosols for inhalation toxicology studies using specified organic components as surrogates for the particulate emissions generated by diesel internal combustion engines. This

John M. Veranth; Robert Gelein; Günter Oberdörster

2003-01-01

344

Dissolution of populations of ultrafine grains with applications to feldspars  

NASA Astrophysics Data System (ADS)

Mineral dissolution studies are difficult to interpret when the solid reactant displays a wide range in grain sizes, since the rate of dissolution of the finest grains may not be simply related to their surface area. The transient apparent rate of dissolution of a population of fine-grained reactants is modeled to predict changes to the solution composition, as well as changes in the size distribution of ultra-fine particles as functions of time. The model is applied to the experimental data on Amelia albite of HOLDREN and BERNER (1979) from which both solution composition and grain size distribution have been obtained. The observed size distribution cannot be duplicated if the dissolution rate is proportional to surface area ( i.e.dV/dt = Kr 2); other contributions to the rate, such as dependence on grain size and the specific contributions from edges and corners, must be invoked. The observed grain size distribution and pseudo-parabolic rate can be reproduced when the rate of dissolution of the fine grains is proportional to its radius ( i.e.dV/dt = kr ). The rate constant, k, is consistent with a rate limited by dissolution at the edges of the grains. The possibility of predicting both the contribution of ultra-fine particles to the observed dissolution rate and the time evolution of the grain size distribution makes the model a useful tool for interpreting mineral dissolution data.

Talman, S. J.; Nesbitt, H. W.

1988-06-01

345

Development and application of a particle-particle particle-mesh Ewald method for dispersion interactions.  

PubMed

For inhomogeneous systems with interfaces, the inclusion of long-range dispersion interactions is necessary to achieve consistency between molecular simulation calculations and experimental results. For accurate and efficient incorporation of these contributions, we have implemented a particle-particle particle-mesh Ewald solver for dispersion (r(-6)) interactions into the LAMMPS molecular dynamics package. We demonstrate that the solver's O(N log N) scaling behavior allows its application to large-scale simulations. We carefully determine a set of parameters for the solver that provides accurate results and efficient computation. We perform a series of simulations with Lennard-Jones particles, SPC/E water, and hexane to show that with our choice of parameters the dependence of physical results on the chosen cutoff radius is removed. Physical results and computation time of these simulations are compared to results obtained using either a plain cutoff or a traditional Ewald sum for dispersion. PMID:23145717

Isele-Holder, Rolf E; Mitchell, Wayne; Ismail, Ahmed E

2012-11-01

346

Associations of Fine and Ultrafine Particulate Air Pollution With Stroke Mortality in an Area of Low Air Pollution Levels  

Microsoft Academic Search

Background and Purpose—Daily variation in outdoor concentrations of inhalable particles (PM10 10 m in diameter) has been associated with fatal and nonfatal stroke. Toxicological and epidemiological studies suggest that smaller, combustion-related particles are especially harmful. We therefore evaluated the effects of several particle measures including, for the first time to our knowledge, ultrafine particles (0.1 m) on stroke. Methods—Levels of

Jaana Kettunen; Timo Lanki; Pekka Tiittanen; Pasi P. Aalto; Tarja Koskentalo; Markku Kulmala; Veikko Salomaa; Juha Pekkanen

2010-01-01

347

Development of an improved positron emission particle tracking system  

Microsoft Academic Search

An improved Positron Emission Particle Tracking (PEPT) system has been developed for the non-intrusive investigation of solids flow in a gas-solids Interconnected Fluidised Bed (IFB) reactor. This system tracks continuously the 3D location of a single positron emitting particle. This particle has the same size and density as the solids and can be made as small as 500 ?m. The

C. S. Stellema; J. Vlek; R. F. Mudde; J. J. M. de Goeij; C. M. van den Bleek

1998-01-01

348

Measurement of aerosol number size distributions in the Yangtze River delta in China: Formation and growth of particles under polluted conditions  

Microsoft Academic Search

Particle size distribution is important for understanding the sources and effects of atmospheric aerosols. In this paper we present particle number size distributions (10nm–10?m) measured at a suburban site in the fast developing Yangtze River Delta (YRD) region (near Shanghai) in summer 2005. The average number concentrations of ultrafine (10–100nm) particles were 2–3 times higher than those reported in the

Jian Gao; Tao Wang; Xuehua Zhou; Waishing Wu; Wenxing Wang

2009-01-01

349

Mössbauer studies of the ultrafine antiferromagnetic cores of ferritin  

NASA Astrophysics Data System (ADS)

The ultrafine iron cores found within the iron-storage protein ferritin are of interest to both the molecular biologist and physicist. The manner in which the protein shell (apoferritin) takes up, releases and sequesters iron is of great biological importance. Also, due to their nano-size (?8 nm), the magnetically ordered cores are singly domained. Such particles possess interesting magnetic relaxation and dynamic properties for which Mössbauer spectroscopy is an ideal analytic tool. Horse ferritin molecules iron-loaded artificially contain ferrihydrite-like cores which behave as superparamagnets due to their nano-size. An anomalous decrease in the f-factor occurs above the blocking temperature of the superparamagnetic particles. This has been attributed to a magnetostriction effect resulting from superparamagnetic switching.

Hawkins, C.; Williams, J. M.; Hudson, A. J.; Andrews, S. C.; Treffry, A.

1994-12-01

350

Design and fabrication of ultrafine piezoelectric composites.  

PubMed

Making fine scale (< 20 microm) piezoelectric composites for high frequency (> 50 MHz) ultrasound transducers remains challenging. Interdigital phase bonding (IPhB), described in this paper, presents a new technique developed to make piezoelectric composites at the ultrafine scale using a conventional dicing saw. Using the IPhB technique, a composite structure with a pitch that is less than the dicing saw blade thickness can be created. The approach is flexible enough to make composites of different combination of pitch and volume ratio. Using a conventional dicing saw with a 50 microm thick blade, composite with a 25 microm pitch and a volume ratio of 61 percent are fabricated. Such a composite is suitable for fabrication of ultrasonic transducers and arrays with central frequencies of up to 85 MHz. Single element transducers working at central frequencies of 50-60 MHz were made of these composites as a mean to characterize the acoustic performance. Measurement results of the transducers show that the longitudinal electromechanical coupling coefficient is greater than 0.6 and that there are no noticeable lateral resonances in the frequency range of 55-150 MHz. Design criteria for fine scale elements are also discussed based on theoretical results from finite element analysis (FEA). PMID:16003926

Yin, J; Lukacs, M; Harasiewicz, K A; Foster, F S

2005-01-01

351

Synthesis of ultrafine powders by microwave heating  

DOEpatents

A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has been removed. The resulting material is an ultrafine powder. This method can be used to make Al.sub.2 O.sub.3, NiO+Al.sub.2 O.sub.3 and NiO as well as a number of other materials including GaBa.sub.2 Cu.sub.3 O.sub.x.

Meek, Thomas T. (Knoxville, TN); Sheinberg, Haskell (Los Alamos, NM); Blake, Rodger D. (Santa Fe, NM)

1988-01-01

352

Synthesis of ultrafine powders by microwave heating  

DOEpatents

A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has dissolved. The resulting material is an ultrafine powder. This method can be used to make Al/sub 2/O/sub 3/, NiO /plus/ Al/sub 2/O/sub 3/ and NiO as well as a number of other materials including GaBa/sub 2/Cu/sub 3/O/sub x/. 1 tab.

Meek, T.T.; Sheinberg, H.; Blake, R.D.

1987-04-24

353

Increased inflammation and intracellular calcium caused by ultrafine carbon black is independent of transition metals or other soluble components  

PubMed Central

OBJECTIVES—Particulate air pollution has been shown to cause adverse health effects, and the ultrafine particle component has been implicated. The aim of the present study was to investigate whether an ultrafine particle exerted its effects through transition metals or other soluble factors released from the surface of the particles.?METHODS—Both in vitro and in vivo models were used to test the imflammogenicity of carbon black (CB) and ultrafine carbon black (UfCB) and the role of transition metals was investigated by treating the particles with desferrioxamine mesylate (desferal), a transition metal chelator. Rats were instilled with particles and the cell population assessed by bronchoalveolar lavage (BAL). Calcium homeostasis in macrophages was assessed with a fluorimetric technique.?RESULTS—UfCB was inflammogenic compared with CB when instilled into Wistar rat lungs, an effect which could not be ameliorated by desferal treatment of the particles. Particle leachates produced no significant inflammation in vivo. In vitro experiments showed that the cytosolic calcium ion concentration in Mono Mac 6 cells was increased significantly after UfCB treatment and treatment of particles with desferal did not alter these effects. Particle leachates had no effect on cytosolic calcium ion concentration. Iron was not detected in leachates of the particles with the desferal assay, however, ng/mg of particles were detectable in citrate leachates with inductively coupled plasma-mass spectrometry (ICP-MS).?CONCLUSIONS—The increased inflammogenicity of UfCB compared with CB cannot be explained by soluble transition metals released from or by accumulation of iron at the particle surface. Differences may be accounted for by increased surface area or particle number.???Keywords: ultrafine; calcium; transition metals

Brown, D; Stone, V; Findlay, P; MacNee, W; Donaldson, K

2000-01-01

354

Processing, Application and Characterization of (Ultra)fine and Nanometric Materials in Energetic Compositions  

NASA Astrophysics Data System (ADS)

The energetic materials research at TNO Defence, Security and Safety, The Netherlands is focusing at the development and characterization of explosives (insensitive munitions), gun/rocket propellants and pyrotechnic compositions and their ingredients. The application of reactive, (ultra)fine and nanometric materials in these compositions has gained increased interest over the past few years. Current research topics focus on the processing, application and characterization of (1) (ultra)fine energetic crystals and composite nano-clusters in plastic bonded explosives, (2) metastable intermolecular composites (MICs) and (3) self-propagating high-temperature synthesis (SHS). In this paper these topics will be highlighted in more detail.

van der Heijden, A. E. D. M.; Bouma, R. H. B.; Carton, E. P.; Martinez Pacheco, M.; Meuken, B.; Webb, R.; Zevenbergen, J. F.

2006-07-01

355

Microstructural Evolution and Mechanical Proerties of Ti(Ni, Fe)Sn Ultrafine Eutectic Alloys  

Microsoft Academic Search

Ultrafine eutectic alloys have been developed in Ti-Ni, Ti-Fe and Ti-(Ni, Fe)-Sn alloys. The Ti76Ni24 and (Ti74Ni26)97Sn3 ultrafine eutectic alloys consist of a mixture of alpha-Ti and Ti2Ni phases, and beta-Ti(Sn) and Ti2Ni phases, respectively, whereas the Ti70.5Fe29.5 and (Ti70.5Fe29.5)97Sn3 alloys are composed by a mixture of beta-Ti(Sn) and FeTi phases with relatively spherical colony. The compression tests of Ti76Ni24,

Dong Hyouk Pi; Ki Buem Kim; Jin Man Park; Jun Hee Han; Do Hyang Kim

2009-01-01

356

Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage.  

PubMed Central

The objectives of this study were to determine whether differences in the size and composition of coarse (2.5-10 micro m), fine (< 2.5 microm), and ultrafine (< 0.1 microm) particulate matter (PM) are related to their uptake in macrophages and epithelial cells and their ability to induce oxidative stress. The premise for this study is the increasing awareness that various PM components induce pulmonary inflammation through the generation of oxidative stress. Coarse, fine, and ultrafine particles (UFPs) were collected by ambient particle concentrators in the Los Angeles basin in California and used to study their chemical composition in parallel with assays for generation of reactive oxygen species (ROS) and ability to induce oxidative stress in macrophages and epithelial cells. UFPs were most potent toward inducing cellular heme oxygenase-1 (HO-1) expression and depleting intracellular glutathione. HO-1 expression, a sensitive marker for oxidative stress, is directly correlated with the high organic carbon and polycyclic aromatic hydrocarbon (PAH) content of UFPs. The dithiothreitol (DTT) assay, a quantitative measure of in vitro ROS formation, was correlated with PAH content and HO-1 expression. UFPs also had the highest ROS activity in the DTT assay. Because the small size of UFPs allows better tissue penetration, we used electron microscopy to study subcellular localization. UFPs and, to a lesser extent, fine particles, localize in mitochondria, where they induce major structural damage. This may contribute to oxidative stress. Our studies demonstrate that the increased biological potency of UFPs is related to the content of redox cycling organic chemicals and their ability to damage mitochondria.

Li, Ning; Sioutas, Constantinos; Cho, Arthur; Schmitz, Debra; Misra, Chandan; Sempf, Joan; Wang, Meiying; Oberley, Terry; Froines, John; Nel, Andre

2003-01-01

357

Design of ultra-fine nonwovens via electrospinning of Nylon 6: Spinning parameters and filtration efficiency  

Microsoft Academic Search

Electrospinning and its application in filtration area are worthwhile to look into as the large surface-to-volume ratio of nanoweb may affect the filtration efficiency by possibly giving more particle-capture sites. In this study, Nylon 6 is electrospun to produce ultra-fine nonwovens, and its characteristics as filter media are investigated. Electrospinning parameters including solution concentration, tip-to-collector distance, and the feed rate

Shu Zhang; Woo Sub Shim; Jooyoun Kim

2009-01-01

358

Increased calcium influx in a monocytic cell line on exposure to ultrafine carbon black  

Microsoft Academic Search

ABSTRACT: Ultrafine particles have been shown,to induce pro-inflammatory,effects both in vivo and,in vitro. Increased expression of pro-inflammatory,genes probably requires the activation of specific transcription factors such as nuclear factor kappa,B (NF-kB) via a number,of possible pathways,including,Ca,Dept of Health Risk Analysis and Toxicology, University of Maastricht, Maastricht, The Netherlands. **MRC Tox- icology Unit, University of Leicester, Lei-

V. Stone; M. Tuinman; J. E. Vamvakopoulos; J. Shaw; D. Brown; S. Petterson; S. P. Faux; P. Borm; W. MacNee; F. Michaelangeli; K. Donaldson

2000-01-01

359

A novel synthesis of phase-pure ultrafine YAG:Tb phosphor with different Tb concentration  

Microsoft Academic Search

Ultrafine luminescent yttrium aluminum garnet (YAG):Tb powders doped with different Tb concentration are prepared by a nitrate–citrate sol–gel combustion process. Single-phase cubic YAG:Tb crystalline is obtained at 800 °C by directly crystallizing from amorphous materials as determined by X-ray diffraction (XRD) techniques. The resultant YAG:Tb powders heat-treated at 1000 °C are uniform and in good dispersity with particle size of

Jun-ji Zhang; Jin-wei Ning; Xue-jian Liu; Yu-bai Pan; Li-ping Huang

2003-01-01

360

Synthesis of ultrafine spherical YAG:Eu 3+ phosphors by MOCVD  

Microsoft Academic Search

Ultrafine Europium-doped yttrium aluminum garnet (YAG:Eu3+) phosphor powders, with uniform diameters of about 1 ?m, have been prepared by metallorganic chemical vapor deposition (MOCVD). The metal–organic precursors have been characterized by thermogravimetry–differential scanning calorimeter (TG–DSC). The phosphor powders have been identified by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence measurements. It shows that the YAG:Eu3+ particles annealed at 1473 K

Yanhui Li; Jihua Zhang; Qingquan Xiao; Renjie Zeng

2008-01-01

361

Selective hydrogenation of cinnamaldehyde to cinnamyl alcohol over an ultrafine CoB amorphous alloy catalyst  

Microsoft Academic Search

The Co-B amorphous alloy catalyst, in the form of ultrafine particles, was prepared by chemical reduction of CoCl2 with borohydride in aqueous solution. The as-prepared Co-B amorphous catalyst exhibited excellent activity and selectivity to cinnamyl alcohol (CMO) during liquid phase hydrogenation of cinnamaldehyde (CMA). Dependence of the contents of CMA and various products on the reaction time was detected, which

Hexing Li; Xingfan Chen; Minghui Wang; Yeping Xu

2002-01-01

362

In situ TEM studies of deformation mechanisms in nanoindentation of ultrafine-grained and nanocrystalline metals  

NASA Astrophysics Data System (ADS)

The mechanical properties of ultrafine-grained and nanocrystalline materials have received a great deal of recent attention because of their unusual and promising values. However, some of the most important mechanisms of deformation remain unclear. To address this issue, an in situ nanoindentation stage has been used in a transmission electron microscope to explore the deformation behaviors of nanocrystalline aluminum, ultrafine-grained aluminum, and ultrafine-grained iron in real time. The special in situ indentation stage contains a Berkovich-type diamond indenter which can be coarsely actuated by a 3-axis screw-positioner and by a piezoelectric ceramic crystal for fine positioning actual indentation. Two methods are used to fabricate samples that are electron transparent, accessible to the indenter and mechanically stable. In one method, polygranular aluminum films are deposited on wedge-shaped silicon substrates so that the film above the wedge tip is transparent. The grain size of the film can be controlled by adjusting the deposition conditions. Alternatively, thin plates of iron are machined from bulk specimens by FIB. In situ studies of nanocrystalline Al films were carried out under various diffraction conditions. Although it is difficult to image individual nanosized grains, the results suggest that strain is accommodated by grain boundary movement or, more interestingly, by strain-induced grain coarsening. In the ultrafine-grained Al films, strain-induced grain coarsening is also frequently observed during deformation at room temperature. The results show that the strain-induced coarsening is by normal grain growth (that is, by grain boundary migration), which may lead to a dramatic enhancement of the ductility. Strain-induced coarsening is more difficult to achieve in ultrafine-grained iron because of the much lower mobility of the grain boundaries. The lack of grain boundary motion in Fe is attributed to the pinning effect of nano-sized particles at the Fe grain boundaries.

Jin, Miao

363

Time-resolved chemical characterization of aerosol particles down to 6 nm diameter in Stockton, California  

NASA Astrophysics Data System (ADS)

A versatile and compact sampling system has been developed to collect sequential time-resolved, dry aerosol particles down to 6 nm in diameter. Using the same technology as in the water-based condensation particle counters this system collects and deposits dry samples of ambient fine and ultrafine particles in 1mm spots. The size of the deposition area allows reducing collection times by increasing the concentration of particles in the 50-100 ?l volume of solvent used to extract the chemicals of interest.

Eiguren-Fernandez, Arantza; Lewis, Gregory; Spielman, Steven; Hering, Susanne

2013-05-01

364

Massive culture of human liver cancer cells in a newly developed radial flow bioreactor system: Ultrafine structure of functionally enhanced hepatocarcinoma cell lines  

Microsoft Academic Search

Summary  With a view to initiating clinical trials, cell morphology and function for a newly developed artificial liver support system\\u000a employing highly functional human liver cell line, FLC-7, cultured in a radial flow bioreactor were compared to cells grown\\u000a in a conventional monolayer culture.\\u000a \\u000a The radial flow bioreactor consists of a vertically extended cylindrical matrix comprised of porous glass bead microcarriers

Masaaki Kawada; Seishi Nagamori; Hideki Aizaki; Kenichi Fukaya; Minoru Niiya; Tomokazu Matsuura; Hajime Sujino; Satoshi Hasumura; Hitoshi Yashida; Satoru Mizutani; Hiroshi Ikenaga

1998-01-01

365

Prototype development and testing of ultrafine grain NZP ceramics. Quarterly technical progress report No. 3, October 28, 1995--January 27, 1996  

SciTech Connect

Caterpillar has been developing advanced low-heat-rejection (LHR) engine designs because by insulating the combustion chamber components for reduced heat rejection, improved fuel economy and emission reduction can be achieved. The insulation eliminates heat loss during the closed portion of the cycle and increases the combustion temperature. Increased combustion temperatures improve emissions by reducing the amount of particulate or smoke. The higher combustion temperatures also provide additional energy to drive a turbocharger that, in turn, improves the overall efficiency of the engine system and results in increased fuel economy.

Brown, J.J.

1996-02-08

366

Development of a particle monitor for the CFFF  

SciTech Connect

To evaluate and improve the performance of particulate control devices (dry electrostatic precipitator or DESP, wet electrostatic precipitator or WESP, Baghouse or BH), the entering particle loading, and size distribution if measurable, is needed. Standard extraction methods provide this data but we labor intensive and thus can not provide this data on-line in near-real-time as needed to determine best particulate device settings for changing operating conditions. Furthermore, the extreme particle number density of the solids in the process stream (10{sup 7} particles/cm{sup 3}) and the small particle sizes (mass mean diameter 0.5--1.0 {mu}m) are outside the capability of existing near-real-time particle loading and sizing devices. Thus, a particulate sample extraction and dilution system (SEDS) was constructed to allow on-line, near continuous determination of solid particulate size distribution with loading in the flue gas entering the particulate cleanup systems. The US Department of Energy Coal Fired Flow Facility (CFFF) SEDS was modeled on a Southern Research Institute developed system which dilutes the sampled flue gas to reduce moisture content, acid mist content, temperature and particulate loading as needed to allow direct, near continuous measurement using commercially available instrumentation. Because the 0.25--1.5 {mu}m particles which present the greatest difficulty for successful cleaning by an electrostatic precipitator are difficult to charge and are produced in large numbers by the high temperature MHD combustion, the CFFF SEDS was designed to measure primarily this size particles. In addition to the measurement uncertainties of the commercially obtained and calibrated particle counting instrument in the SEDS, the dilution process introduces other uncertainties. These uncertainties are being evaluated as the SEDS construction is being completed and as best operating parameters are being determined.

Parker, J.L.; Giel, T.V.; Winkleman, B.C.; Hodges, M.E.; Holt, J.K.; Douglas, J.R.

1993-06-01

367

Thermal stability of ultrafine-grained austenitic stainless steels  

Microsoft Academic Search

Ultrafine-grained 316 and 304 austenitic stainless steel samples have been produced by high pressure torsion. Their microstructure, after deformation and annealing at a temperature in the 350–900°C range, has been characterized using several techniques (transmission electron microscopy, X-ray diffraction, Mössbauer spectroscopy). The average grain size in the ultrafine-grained 316 is about 40nm while it is larger in the ultrafine-grained 304

A. Etienne; B. Radiguet; C. Genevois; J.-M. Le Breton; R. Valiev; P. Pareige

2010-01-01

368

Antimicrobial PLGA ultrafine fibers: interaction with wound bacteria.  

PubMed

The structure and functions of polymer nanofibers as wound dressing materials have been well investigated over the last few years. However, during the healing process, nanofibrous mats are inevitably involved in dynamic interactions with the wound environment, an aspect not explored yet. Potential active participation of ultrafine fibers as wound dressing material in a dynamic interaction with wound bacteria has been examined using three wound bacterial strains and antimicrobial fusidic acid (FA)-loaded electrospun PLGA ultrafine fibers (UFs). These were developed and characterized for morphology and in-use pharmaceutical attributes. In vitro microbiological studies showed fast bacterial colonization of UFs and formation of a dense biofilm. Interestingly, bacterial stacks on UFs resulted in a remarkable enhancement of drug release, which was associated with detrimental changes in morphology of UFs in addition to a decrease in pH of their aqueous incubation medium. In turn, UFs by allowing progressively faster release of bioactive FA eradicated planktonic bacteria and considerably suppressed biofilm. Findings point out the risk of wound reinfection and microbial resistance upon using non-medicated or inadequately medicated bioresorbable fibrous wound dressings. Equally important, data strongly draw attention to the importance of characterizing drug delivery systems and establishing material-function relationships for biomedical applications under biorelevant conditions. PMID:21396444

Said, Somiraa S; Aloufy, Affaf K; El-Halfawy, Omar M; Boraei, Nabila A; El-Khordagui, Labiba K

2011-03-09

369

Cryogenic detection of particles: Development effort in the United States  

SciTech Connect

The development of cryogenic detectors of particles, with emphasis on large mass devices, has been reviewed. Most groups are still tooling up and exploring basic properties of sensors. The main discussion themes are summarized and some of the early experimental results are described.

Sadoulet, B.

1987-05-01

370

Low-temperature preparation of ultrafine rare-earth iron garnets  

SciTech Connect

Ultrafine rare-earth iron garnets, (R{sub 3}Fe{sub 5}O{sub 12} where R = Sm, Tb, Dy, Ho, Er, Yb, (YGd), and (YNd)) have been prepared by thermal decomposition of a citrate precursor, R{sub 3}Fe{sub 5}(cit){sub 25} {center dot} (36 + N)H{sub 2}O. The precursors decompose at lower temperatures, below 450{degrees}C, and are characterized using DTA, DSC, TG, and IR spectroscopy. Ultrafine amorphous garnets having particle size 10 to 35 nm and surface area 30 to 75 m{sup 2}/g have been obtained and characterized by XRD, TEM, Mossbauer spectra, particle size analysis, and magnetic and surface area measurements. Superparamagnetism indicates the ultrafine characteristics of the garnet materials. The nature of crystallite aggregates and agglomerates is of special interest because it represents finite clusters. An intercrystallite bond exists between crystallites having 1.0- to 1.5-nm size. The rupture of intercrystallite bonds during crystallization leads to monolith formation.

Sankaranarayanan, V.K.; Gajbhiye, N.S. (Dept. of Chemistry, Indian Institute of Technology, Kanpur (IN))

1990-05-01

371

Gene expression profiles in rat lung after inhalation exposure to C 60 fullerene particles  

Microsoft Academic Search

Concern over the influence of nanoparticles on human health has risen due to advances in the development of nanotechnology. We are interested in the influence of nanoparticles on the pulmonary system at a molecular level. In this study, gene expression profiling of the rat lung after whole-body inhalation exposure to C60 fullerene (0.12mg\\/m3; 4.1×104 particles\\/cm3, 96nm diameter) and ultrafine nickel

Katsuhide Fujita; Yasuo Morimoto; Akira Ogami; Toshihiko Myojyo; Isamu Tanaka; Manabu Shimada; Wei-Ning Wang; Shigehisa Endoh; Kunio Uchida; Tetsuya Nakazato; Kazuhiro Yamamoto; Hiroko Fukui; Masanori Horie; Yasukazu Yoshida; Hitoshi Iwahashi; Junko Nakanishi

2009-01-01

372

Development of surfaces repelling negatively buoyant solid particles  

NASA Astrophysics Data System (ADS)

Using a hybrid computational method that integrates the lattice Boltzmann model for fluid dynamics and the lattice spring model for solids, we examine the motion of negatively buoyant solid microparticles in shear flow near a solid wall decorated with regularly distributed rigid posts. The posts are arranged in a square pattern and tilted relative to the flow direction. We show that when rigid posts are tilted against flow, secondary flows emerge that prevent the deposition of suspended particles on the solid surface. We probe the effect of post geometry on the development of secondary flows and identify the optimal post architecture in terms of the mass of levitated solid particles. Our results are useful for designing anti-fouling surfaces that repel colloidal particles carried by fluid.

Semmler, Carina; Alexeev, Alexander

2011-03-01

373

Development of 2D Ionization Chamber for Particle Therapy  

NASA Astrophysics Data System (ADS)

Recently rapid growth in particle therapy has imposed new detector developments for quality assurance (QA) purposes. Relatively high dose deposition from proton or carbon ion beam requires stringent performance from detectors. Cyclotron, synchrotron, or future laser driven accelerators represent DC and pulse sources which need different timing designs in electronics. Dose and position measurements of particle beams can serve clinical, beam diagnosis and QA purposes. We categorize the parameters of detectors - electronics, DAQ, and simulation--to serve for later optimizations. Gaseous detector is preferred because of its radiation hardness, and operation at ionization mode provides stable condition. We present our progresses in 2D ionization chamber development. Basic studies are carried out on 1D ionization chamber, which consists of 16 6-mm-wide strips. Results of measuring electron and proton beams are compared with MC simulations. 2D array ionization chamber design is optimized and based on 1D prototype measurements.

Ho, Chi-Li

2010-11-01

374

Papillomavirus-like particles and HPV vaccine development  

Microsoft Academic Search

Human papillomavirus-like particles (VLPs), self-assembled after high level expression of the papillomavirus L1 virion capsid protein in non-mammalian cells, are attractive candidates for a subunit vaccine to prevent genital HPV infection and the subsequent development of cervical cancer. In animal studies, purified VLPs induce high titers of antibodies against conformational type specific L1 epitopes. These antibodies neutralize homologous virions in

John T. Schiller; Douglas R. Lowy

1996-01-01

375

The Pandora Software Development Kit for Particle Flow Calorimetry  

NASA Astrophysics Data System (ADS)

Pandora is a robust and efficient framework for developing and running pattern-recognition algorithms. It was designed to perform particle flow calorimetry, which requires many complex pattern-recognition techniques to reconstruct the paths of individual particles through fine granularity detectors. The Pandora C++ software development kit (SDK) consists of a single library and a number of carefully designed application programming interfaces (APIs). A client application can use the Pandora APIs to pass details of tracks and hits/cells to the Pandora framework, which then creates and manages named lists of self-describing objects. These objects can be accessed by Pandora algorithms, which perform the pattern-recognition reconstruction. Development with the Pandora SDK promotes the creation of small, re-usable algorithms containing just the kernel of a specific operation. The algorithms are configured via XML and can be nested to perform complex reconstruction tasks. As the algorithms only access the Pandora objects in a controlled manner, via the APIs, the framework can perform most book-keeping and memory-management operations. The Pandora SDK has been fully exploited in the implementation of PandoraPFA, which uses over 60 algorithms to provide the state of the art in particle flow calorimetry for ILC and CLIC.

Marshall, J. S.; Thomson, M. A.

2012-12-01

376

Impact ionization mass spectrometer instrument development for cosmic dust particles  

NASA Astrophysics Data System (ADS)

A new instrument is under development to analyze the chemical composition of dust particles in-situ. The CRIA (Cosmic dust Reflectron for Isotopic Analysis) instrument is a mass spectrometer that analyzes the ions generated upon the hypervelocity impact of cosmic dust particles on a solid surface. The large sensitive area of the instrument (40 cm in diameter) makes the instrument capable of measuring the composition of interstellar dust particles that have a low flux. The laboratory prototype of the instrument has been previously tested in laboratory conditions using laser ablation and the Heidelberg dust acceleration facility. The mass resolution of the instrument is approximately m/dm ~ 200. Here we report on the progress of the technical readiness level (TRL) of the instrument. The development is done as part of a graduate level course offered at the Aerospace Engineering department at the University of Colorado. In the class the students design and fabricate the instrument to specified requirement and perform the environmental tests for the applicable TRL level. The details of the class setup are discussed. This project is funded by the Laboratory of Atmospheric and Space Physics (LASP) and the Aerospace Engineering Department at the University of Colorado, Boulder. The instrument concept development was funded by NASA.

Sternovsky, Z.; Palo, S.; Li, X.; Brower, L.; Chang, L.; Lee, D.; Pilinski, M.; Salehi, M.; Tu, W.; Turner, D.; Amyx, K.; Horanyi, M.; Gruen, E.; Knappmiller, S.; Robertson, S.; Srama, R.; Auer, S.

2007-12-01

377

Correlation between particle size, in vivo particle persistence, and lung injury.  

PubMed Central

Dosimetry parameters such as deposition, clearance, retention, and translocation and dissolution of inhaled particles in and to different lung compartments may be important for the persistence of particles in the lung and may correlate with adverse pulmonary effects. We investigated such correlations using a model involving TiO2 particles of two particle sizes (20 nm diameter, ultrafine; 250 nm diameter, fine) of the same crystalline structure (anatase). A 12-week inhalation experiment in rats resulted in a similar mass deposition of the two particle types in the lower respiratory tract. The ultrafine particles elicited a persistently high inflammatory reaction in the lungs of the animals compared to the larger-sized particles. In the postexposure period (up to 1 year) retention in the alveolar space per se was not different between fine and ultrafine TiO2. However, the following differences between the particle types were noted: a significantly different total pulmonary retention, both quantitatively (significantly prolonged retention of the ultrafine TiO2) and qualitatively (increased translocation to the pulmonary interstitium and persistence there of the ultrafine TiO2); greater epithelial effects (Type II cell proliferation; occlusion of pores of Kohn) and the beginning of interstitial fibrotic foci with ultrafine TiO2; significant sustained impairment of alveolar macrophage function after ultrafine TiO2 exposure as measured by the clearance of test particles. A correlation between particle surface area and effects was observed. A comparison of the adverse reactions with dosimetric parameters of TiO2 in different lung compartments in the postexposure period showed a correlation of the persistence of effects in both the alveolar and interstitial space with the persistence of particles in the respective compartment.

Oberdorster, G; Ferin, J; Lehnert, B E

1994-01-01

378

Moessbauer Studies of Iron-Based Ultrafine Coal Liquefaction Catalysts.  

NASA Astrophysics Data System (ADS)

Mossbauer spectroscopy has been used to investigate the structure and size dispersion of a variety of ultrafine iron-based catalysts for direct coal-liquefaction. In the as-prepared state, iron was chemically incorporated into the coal as a FeOOH polymorph, while catalysts prepared separately were usually present as Fe_2 O_3. The Mossbauer spectra of these catalysts showed pronounced superparamagnetic effects. The superparamagnetic relaxation spectra obtained at various temperatures were analyzed using a novel fitting model to determine the particle size distribution of these catalysts. The resulting size distributions are in the nanometer range and agree reasonably well with size information obtained by Scanning Transmission Electron Microscopy (STEM), SQUID Magnetometry, and X-Ray Diffraction (XRD). Investigation of a 30A FeOOH catalyst by Mossbauer spectroscopy revealed that the recoilless fraction decreased dramatically with temperature, becoming effectively zero at 50K. This effect has been explained on the basis of a combined effect of the recoil of the particle and the particle motion due to thermal agitation. The mean square amplitude of particle-motion was derived as a function of temperature. It was shown that by application of pressure or by suspending the particles in a wax matrix, the recoilless fraction could be increased significantly. During direct coal liquefaction (DCL), the highly dispersed ferric iron rapidly reacts with H_2 S to form pyrrhotite (Fe_{(1 -x)}S), where x is the vacancy concentration. If insufficient sulfur is present in the reactor to convert all of the iron to pyrrhotite, the remainder is left in the form of a superparamagnetic oxide. Mossbauer studies were done on a number of catalysts after DCL or related hydrotreatment reaction to determine the structure and vacancy content of the pyrrhotites, which varied from 5 to 11% for the limited number of samples studied here.

Ganguly, Bhaswati

379

Measurements of the effects of humidity on radio-aerosol penetration through ultrafine capillaries  

SciTech Connect

The purpose of this research was to examine the effects of humidity on radio-aerosol penetration through ultrafine capillaries. A number of tests were conducted at relative humidities of 20%, 50%, and 80%, with sampling times of 20, 40, and 60 min. The radio-aerosol consisted of polystyrene particles with a diameter of 0.1 {micro}m. The ultrafine capillaries had a diameter of 250 {micro}m. The data from these tests varied significantly. These results made the identification of radio-aerosol penetration trends inconclusive. The standard deviation for all penetration data ranged from 3% to 30%. The results of this study suggest that a better control of the experimental parameters was needed to obtain more accurate data from experiments associated with radio-aerosol penetration in the presence of moisture. The experimental parameters that may have contributed to the wide variance of data, include aerosol flow, radio-aerosol generation, capillary characteristics, humidity control, and radiation measurements. It was the uncertainty of these parameters that contributed to the poor data which made conclusive deductions about radio-aerosol penetration dependence on humidity difficult. The application of this study is to ultrafine leaks resulting from stress fractures in high-level nuclear waste transportation casks under accident scenarios.

Cullen, C.

1996-08-01

380

Inferring the Sources of Fine and Ultrafine Particulate Matter at Downwind Receptor Sites in the Los Angeles Basin Using Multiple Continuous Measurements Special Issue of Aerosol Science and Technology on Findings from the Fine Particulate Matter Supersites Program  

Microsoft Academic Search

Recent studies that have found increased health effects of atmospheric ultrafine particulate matter (PM) have refocused attention on particle number rather than particle mass concentrations as a relevant measurement of PM pollution. As part of the Southern California Supersite program, ambient particle characteristics were measured over 13 months at three different sites in the eastern portion of the Los Angeles

Philip M. Fine; Si Shen; Constantinos Sioutas

2004-01-01

381

Microstructure and impact properties of ultra-fine grained tungsten alloys dispersed with TiC  

Microsoft Academic Search

In order to improve both the low temperature toughness and the resistance to embrittlement by recrystallization and irradiation in currently available tungsten and its alloys, ultra-fine grained tungsten alloys with TiC additions of 0.2 and 0.5 wt% were developed by mechanical alloying and hot isostatic pressing. It is shown that the impact toughness of the developed alloys is very sensitive

Yuji Kitsunai; Hiroaki Kurishita; Hideo Kayano; Yutaka Hiraoka; Tadashi Igarashi; Tomohiro Takida

1999-01-01

382

Optimization of multigravity separation for recovery of ultrafine coal  

SciTech Connect

Enhanced gravity separation appears to be one of the most promising methods for processing all types of < 200-{mu}m coal feeds and tailings. Systems based on this technology are reviewed, and the results of investigations based on C900 Multi-Gravity Separator tests conducted to assess the treatment of < 200-{mu}m, extremely difficult-to-wash coal settling pond tailings are presented. Multi-Gravity Separator processing tests of ultra-fine tailings with a high clay particle size content (22.6% < 10 {mu}m and 60.1 % < 40 {mu}m) and a 69.56% ash content show that this material can be effectively treated after desliming (< 10 {mu}m) of clay-size particles to produce a coal with a 20.6% ash at a separator combustible material recovery of 69.3 %. Desliming is shown to be critical in reducing coal ash content and combustible material recovery. Similar improvements are anticipated in the recovery and separation processes for other enhanced gravity separation systems from the desliming of feeds. Although not a conventional form of treating Multi-Gravity Separator data, the existence of well-defined polynomial relationships based on the product of drum shake amplitude and shake frequency relative to product coal recovery, product ash content and yields at varying wash water flows is demonstrated. Low-amplitude and intermediate-to high-frequency bed agitation are shown to produce optimum ash reduction results.

Menendez, M.; Gent, M.; Torano, J.; Diego, I. [University of Oviedo, Oviedo (Spain)

2007-11-15

383

Susceptibility to inhaled flame-generated ultrafine soot in neonatal and adult rat lungs.  

PubMed

Over a quarter of the U.S. population is exposed to harmful levels of airborne particulate matter (PM) pollution, which has been linked to development and exacerbation of respiratory diseases leading to morbidity and mortality, especially in susceptible populations. Young children are especially susceptible to PM and can experience altered anatomic, physiologic, and biological responses. Current studies of ambient PM are confounded by the complex mixture of soot, metals, allergens, and organics present in the complex mixture as well as seasonal and temporal variance. We have developed a laboratory-based PM devoid of metals and allergens that can be replicated to study health effects of specific PM components in animal models. We exposed 7-day-old postnatal and adult rats to a single 6-h exposure of fuel-rich ultrafine premixed flame particles (PFPs) or filtered air. These particles are high in polycyclic aromatic hydrocarbons content. Pulmonary cytotoxicity, gene, and protein expression were evaluated at 2 and 24 h postexposure. Neonates were more susceptible to PFP, exhibiting increased lactate dehydrogenase activity in bronchoalveolar lavage fluid and ethidium homodimer-1 cellular staining in the lung in situ as an index of cytotoxicity. Basal gene expression between neonates and adults differed for a significant number of antioxidant, oxidative stress, and proliferation genes and was further altered by PFP exposure. PFP diminishes proliferation marker PCNA gene and protein expression in neonates but not adults. We conclude that neonates have an impaired ability to respond to environmental exposures that increases lung cytotoxicity and results in enhanced susceptibility to PFP, which may lead to abnormal airway growth. PMID:21914721

Chan, Jackie K W; Fanucchi, Michelle V; Anderson, Donald S; Abid, Aamir D; Wallis, Christopher D; Dickinson, Dale A; Kumfer, Benjamin M; Kennedy, Ian M; Wexler, Anthony S; Van Winkle, Laura S

2011-09-13

384

Study of the Group Paramagnetism of Ferrimagnetic Particles by the Moessbauer Effect.  

National Technical Information Service (NTIS)

The group paramagnetism of the ultrafine ferrimagnetic S-FeOOH particles with the help of the Mossbauer effect is studied. The experimental Mossbauer spectra are compared with the spectra calculated according to the Wickman's model for particles of differ...

P. O. Voznyuk V. N. Dubinin

1974-01-01

385

COMBUSTION GENERATED PARTICLES - EXAMINING BOTH DIESEL AND COAL PM CHARACTERIZATION AND HEALTH EFFECTS  

EPA Science Inventory

Processes that form fine and ultrafine particulate matter (PM) are of regulatory interest because there is evidence that these particles cause adverse health effects. Different fuels and combustion technologies produce particles with widely different physical and chemical propert...

386

Nuclear microprobe investigation of the penetration of ultrafine zinc oxide into human skin affected by atopic dermatitis  

NASA Astrophysics Data System (ADS)

Skin penetration is one of the potential routes for nanoparticles to gain access into the human body. Ultrafine metal oxides, such as titanium dioxide and zinc oxide are widely used in cosmetic and health products like sunscreens. These oxides are potent UV filters and the particle size smaller than 200 nm makes the product more transparent compared to formulations containing coarser particles. The present study continues the work carried out in the frame of the NANODERM: "Quality of skin as a barrier to ultrafine particles" European project and complements our previous investigations on human skin with compromised barrier function. Atopic dermatitis (a type of eczema) is an inflammatory, chronically relapsing, non-contagious skin disease. It is very common in children but may occur at any age. The exact cause of atopic dermatitis is unknown, but is likely due to a combination of impaired barrier function together with a malfunction in the body's immune system. In this study, skin samples were obtained from two patients suffering from atopic dermatitis. Our results indicate that the ultrafine zinc oxide particles, in a hydrophobic basis gel with an application time of 2 days or 2 weeks, have penetrated deeply into the stratum corneum in these patients. On the other hand, penetration into the stratum spinosum was not observed even in the case of the longer application time.

Szikszai, Z.; Kertész, Zs.; Bodnár, E.; Borbíró, I.; Angyal, A.; Csedreki, L.; Furu, E.; Szoboszlai, Z.; Kiss, Á. Z.; Hunyadi, J.

2011-10-01

387

Electroacoustic measurements of sulfide mineral particles  

Microsoft Academic Search

Electroacoustic measurements (AcoustoSizer, Matec Applied Sciences) of zeta potential and particle size distribution are reported on well characterised ultrafine (?5 ?m) sphalerite and galena particles. For both sulfide minerals the zeta potentials determined electroacoustically are in good agreement with those determined using the more conventional microelectrophoresis. The applicability of the electroacoustic technique to sulfide mineral particles is discussed, in particular

C. A Prestidge; W. N Rowlands

1997-01-01

388

Formation of ultra-fine ferrite in hot rolled strip: potential mechanisms for grain refinement  

Microsoft Academic Search

A novel single-pass hot strip rolling process has been developed in which ultra-fine (<2 ?m) ferrite grains form at the surface of hot rolled strip in two low carbon steels with average austenite grain sizes above 200 ?m. Two experiments were performed on strip that had been re-heated to 1250°C for 300 s and air-cooled to the rolling temperatures. The

P. J. Hurley; P. D. Hodgson

2001-01-01

389

An elevated temperature electrospinning process for preparing acyclovir-loaded PAN ultrafine fibers  

Microsoft Academic Search

An elevated temperature electrospinning process was developed for the preparation of drug-loaded polyacrylonitrile (PAN) ultrafine fibers. An additional apparatus for maintaining the electrospinning temperature at a high constant value was fitted on the syringe pump. Acyclovir (ACY)-loaded PAN fibers could be prepared from the co-dissolving dimethyl sulfoxide solutions of PAN and ACY at 80°C. As the temperature increased, the viscosities

Hong-Mei Chen; Deng-Guang Yu

2010-01-01

390

3-D Radargrammetric Modeling of RADARSAT-2 Ultrafine Mode: Preliminary Results of the Geometric Calibration  

Microsoft Academic Search

The geometry and the accuracy of the 3-D cartographic localization of RADARSAT-2 images are being evaluated as part of the Canadian Space Agency's Science and Operational Applications Research program. In a first step, the Toutin's 3-D physical model, previously developed for RADARSAT-1, was adapted to RADARSAT-2 sensor and applied to two ultrafine mode images (U2 and U25) acquired over an

Thierry Toutin; Rene Chenier

2009-01-01

391

3D GEOMETRIC MODELING OF RADARSAT-2 ULTRAFINE MODE USING DIFFERENTIAL GPS DATA  

Microsoft Academic Search

The geometry and the accuracy of the three-dimensional (3-D) cartographic localization of RADARSAT-2 images are being evaluated as part of the Canadian Space Agency's Science and Operational Applications Research program. In a first step, the Toutin's 3-D physical model, previously developed for Radarsat-1, was adapted to Radarsat-2 sensor and applied to two ultra-fine mode images (U2 and U25) acquired over

Thierry Toutin; René Chénier

392

On-line measurement of ultrafine aggregate surface area and volume distributions by electrical mobility analysis: II. Comparison of measurements and theory  

Microsoft Academic Search

Differential mobility analyzers (DMAs) are sometimes used to characterize aerosols that contain aggregates of low fractal dimension. However, these instruments are normally calibrated for spherical particles and the calibrations are not directly applicable to aggregates. A method proposed by Lall and Friedlander [(2006). On-line measurement of ultrafine aggregate surface area and volume distributions by electrical mobility analysis, I: Theoretical analysis.

Anshuman A. Lall; Martin Seipenbusch; Weizhi Rong; Sheldon K. Friedlander

2006-01-01

393

Pulmonary Inflammation After Intraperitoneal Administration of Ultrafine Titanium Dioxide (TiO2) At Rest or in Lungs Primed with Lipopolysaccharide  

Microsoft Academic Search

Nanoparticles are widely used in nanomedicines, including for targeted delivery of pharmacological, therapeutic, and diagnostic agents. Since nanoparticles might translocate across cellular barriers from the circulation into targeted organs, it is important to obtain information concerning the pathophysiologic effects of these particles through systemic migration. In the present study, acute pulmonary responses were examined after intraperitoneal (ip) administration of ultrafine

Changsuk Moon; Hyun-Jeong Park; Youn-Hee Choi; Eun-Mi Park; Vincent Castranova; Jihee Lee Kang

2010-01-01

394

Development of Pressure sensing Particles through SERS and Upconversion  

NASA Astrophysics Data System (ADS)

With the increasing distance of space travel, there is a critical need for non-invasive point-of-care diagnostic techniques. According to the NASA Human Research Roadmap, the ``lack of non-invasive diagnostic imaging capability and techniques to diagnose identified Exploration Medical Conditions involving internal body parts,'' is a critical capability gap for long distance space travel. To address this gap, we developed a novel technique for non-invasive monitoring of strain on implanted devices. We constructed a prototype tension-indicating washer with an upconversion spectrum that depended upon strain. The washer was made of a polydimethylsiloxane (PDMS) mixture with upconversion particles embedded in it. This mixture was cured onto a lenticular lens. Methylene blue dye solution was sealed between the lenticular lens and PDMS so that pressure on the washer displaced the dye and uncovered the upconversion particles. We also began work on a tension-indicating screw based upon surface enhanced Raman spectroscopy (SERS). Future work for this project is to quantitatively correlate the spectral intensity with pressure, further develop SERS washers, and construct SERS and/or upconversion screws or bolts. Non-invasive tension-indicating devices and techniques such as these can be applied to orthopedics, used as a general technique for measuring micro-strain, verifying proper assembly of equipment, and observing/studying bolt loosening.

Widejko, Ryan; Wang, Fenglin; Anker, Jeff

2012-03-01

395

Inversion of ultrafine condensation nucleus counter pulse height distributions to obtain nanoparticle (?3–10 nm) size distributions  

Microsoft Academic Search

Previous work (Ahn and Liu (1990)J. Aerosol. Sci. 21, 249–261; Brockmann (1981) Ph.D. Thesis, University of Minnesota; Rebours et al. (1992)J. Aerosol. Sci. 23, S189–S192; Stolzenburg (1988) Ph.D. thesis, University of Minnesota) has shown that for particles smaller than about 15nm, pulse heights produced by the optical detector in a white-light ultrafine condensation nucleus counter (UCNC; Stolzenburg and McMurry (1991)Aerosol.

Rodney J. Weber; Mark R. Stolzenburg; Spyros N. Pandis; Peter H. McMurry

1998-01-01

396

Multiscale Statistical Model of Fully-Developed Turbulence Particle Accelerations  

NASA Astrophysics Data System (ADS)

Based on the experimental measurement results of fluid particle transverse accelerations in fully developed pipe turbulence published in Nature (2001) by La Porta et al, the present authors recently develop a multiscale statistical model which considers both normal diffusion in molecular scale and anomalous diffusion in vortex scale. This model gives rise to a new probability density function, called Power-Stretched Gaussian Distribution model (PSGD). In this study, we make a further comparison of this statistical distribution model with the well-known Lévy distribution, Tsallis distribution and stretched-exponential distribution. Our model is found to have the following merits: 1) fewer parameters, 2) better fitting with experimental data, 3) more explicit physical interpretation.

Chen, Wen; Sun, Hongguang

397

Synthesis of ultrafine ceramic and metallic powders in a thermal argon rf plasma  

SciTech Connect

Ultrafine powders of SiC, Si/sub 3/N/sub 4/, Ni, and Al/sub 2/O/sub 3/ have been prepared in a rf-plasma reactor, utilizing an induction plasma tube designed at Los Alamos. The primary particle size of the ceramic powders ranges from 5 to 50 nm. Silicon carbide and alumina are ultrapure crystalline powders, while silicon nitride is amorphous for surface areas greater than 100 m/sup 2//g. Plasma nickel powder will sinter to full density at 1073 K.

Vogt, G.J.; Vigil, R.S.; Newkirk, L.R.; Trkula, M.

1985-01-01

398

Ultra-fine coal characterization. 8th quarterly report, December 1, 1985-February 28, 1986  

SciTech Connect

Research continued to relate the beneficiation characteristics of ultra-fine coal to the mineral-matter liberation and the bulk properties of the coal. Washability tests were made on washed coals from the Pittsburgh, Upper Freeport and Pocahontas No. 3 seams following procedures established for midwestern coals. An initial set of flotation modelling experiments on Illinois No. 6 coal were completed and evaluated. Zeta-potential measurements were also made on particles of 5 coals suspended in water of pH 2 to pH 12. 3 refs., 8 figs., 9 tabs.

Smit, F.J.

1986-04-10

399

Pseudophasic extraction method for the separation of ultra-fine minerals  

DOEpatents

An improved aqueous-based extraction method for the separation and recovery of ultra-fine mineral particles. The process operates within the pseudophase region of the conventional aqueous biphasic extraction system where a low-molecular-weight, water soluble polymer alone is used in combination with a salt and operates within the pseudo-biphase regime of the conventional aqueous biphasic extraction system. A combination of low molecular weight, mutually immiscible polymers are used with or without a salt. This method is especially suited for the purification of clays that are useful as rheological control agents and for the preparation of nanocomposites.

Chaiko, David J. (Naperville, IL)

2002-01-01

400

Microbial production of ultrafine-grained magnetite by fermentation processes at room temperature.  

PubMed

A method of producing magnetite nanoparticles was developed through culturing a microorganism designated Haejae-1, Shewanella sp., in the presence of glucose and akaganeite (beta-FeOOH). Haejae-1 isolated from inter-tidal flat sediments was able to produce copious amount of ultrafine magnetite via glucose fermentation extracellularly under anaerobic conditions at room temperature, allowing for easy production, separation, and recovery of the magnetite. TEM observation revealed aggregates of small crystals of ultrafine magnetite which ranged in size from about 2 to 4 nanometers. Magnetic property by SQUID analysis showed the magnetite nanoparticles demonstrate superparamagnetic behavior. As a result, the method of the present study can be used to produce magnetite efficiently using inexpensive means at room temperature. The magnetite is a mineral of a great commercial value in that it is useful, e.g., in magnetic recording devices, drug carriers, and as toner for plain paper copiers. PMID:19198424

Roh, Yul; Kim, Yumi; Lee, Sanghoon; Jang, Heedong; Suh, Yongjae

2008-10-01

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