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1

ADVANCED ULTRAFINE PARTICLE ACCELERATOR  

Microsoft Academic Search

The conceptual design of an Ultrafine Particle Radio Frequency Quadrupole (UFP-RFQ) accelerator is discussed. The results indicate that it is possible to accelerate 1 pm radius Al particles to velocities around 100 km\\/s in 100 m RFQ length. This accelerator can provide variable output particle velocity, with capability of handling different particle materials with different sizes. There are scientific, industrial

D. A. Swenson; A. E. Dabiri; Z. Mikic; D. B. McCall; M. F. Scharff

2

Ultrafine particles in cities.  

PubMed

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

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

2014-05-01

3

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

PubMed Central

Vehicle exhaust is rich in polycyclic aromatic hydrocarbons (PAH) and can be a dominant contributor to ultrafine urban particulate matter (PM). Exposure to ultrafine PM is correlated with respiratory infections and asthmatic symptoms in young children. The lung undergoes substantial growth, alveolarization, and cellular maturation within the first years of life, which may be impacted by environmental pollutants such as PM. PAHs in PM can serve as ligands for the aryl hydrocarbon receptor (AhR) that induces expression of certain isozymes in the cytochrome P-450 superfamily, such as CYP1A1 and CYP1B1, localized in specific lung cell types. Although AhR activation and induction has been widely studied, its context within PM exposure and impact on the developing lung is poorly understood. In response, we have developed a replicable ultrafine premixed flame particle (PFP) generating system and used in vitro and in vivo models to define PM effects on AhR activation in the developing lung. We exposed 7-day neonatal and adult rats to a single 6-h PFP exposure and determined that PFPs cause significant parenchymal toxicity in neonates. PFPs contain weak AhR agonists that upregulate AhR-xenobiotic response element activity and expression and are capable inducers of CYP1A1 and CYP1B1 expression in both ages with different spatial and temporal patterns. Neonatal CYP1A1 expression was muted and delayed compared with adults, possibly because of differences in the enzyme maturation. We conclude that the inability of neonates to sufficiently adapt in response to PFP exposure may, in part, explain their susceptibility to PFP and urban ultrafine PM. PMID:23502512

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

2013-01-01

4

Acute pulmonary effects of ultrafine particles in rats and mice.  

PubMed

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

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

2000-08-01

5

Ultrafine Particles Deposition Inside Passenger Vehicles  

Microsoft Academic Search

Although commuting time typically accounts for only 6% of the day for Americans, it has become a significant source of exposure to ultrafine particles (dp < 0.1 ?m) from vehicular emissions. Particle deposition onto surfaces, as an important particle loss mechanism, has been studied extensively in the indoor environments. However since air velocities, surface area to volume ratios and other

Longwen Gong; Bin Xu; Yifang Zhu

2009-01-01

6

Ultrafine particle and fiber production in microgravity  

NASA Technical Reports Server (NTRS)

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

Webb, George W. (Inventor)

1988-01-01

7

A chemical analyzer for charged ultrafine particles  

NASA Astrophysics Data System (ADS)

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

Gonser, S. G.; Held, A.

2013-04-01

8

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

9

In-cabin ultrafine particle dynamics  

Microsoft Academic Search

To assess the total human health risks associated with human exposure to ultrafine particle (UFP), the concentrations and fates of UFPs in the in-cabin atmospheres must be understood. In order to assess human exposure more accurately and further prevent adverse health effects from UFP exposure in the in-cabins, it is essential to gain insight into UFP transport dynamics between in-cabin

Bin Xu

2010-01-01

10

Measurements of ultrafine bubbles using different types of particle size measuring instruments  

NASA Astrophysics Data System (ADS)

In 2010, we succeeded in measuring the sizes of bubbles generated by our GALF (GAs Liquid Foam) bubble generating system, using particle tracking analysis for the first time, and quantitatively confirmed the generation and presence of ultrafine bubbles measuring around 100 to 200 nm in diameter. After that, we also developed a new technology to generate a high density of ultrafine bubbles and launched our ultrafine bubble generating system (ultrafineGALF) in 2011. This report details several independent measurements of bubbles generated in water by ultrafineGALF, using dynamic light scattering, laser diffraction scattering, particle tracking analysis, and the electrical sensing zone method. It was found that the presence of ultrafine bubbles with a diameter of about 100 to 200 nm could be determined quantitatively using any of these methods.

Kobayashi, Hideaki; Maeda, Shigeo; Kashiwa, Masakazu; Fujita, Toshihiro

2014-08-01

11

The development and field testing of a system for determination of ultrafine activity particle size distribution and working levels  

SciTech Connect

Recent investigations of radon decay products in indoor air have shown that what has been called the unattached'' fraction is in fact an ultrafine size aerosol with diameters in the range of 0.5 to 10 nm. There are a number of difficulties in characterizing particles in this size range. Classical diffusion batteries using screens with high mesh numbers do not have the resolution to give detailed information for the ultra fine range. The use of single screens of differing mesh numbers (Graded Screen Arrays) either in parallel or in a stack configuration can be used to provide these results. However, accurately measuring the activity directly attached to the screens is difficult because of the attachment of some activity to the back side of the screen and the distribution of activity around the individual screen wires. A continuous monitoring system that provides information on both the size and charge distributions on these important size range particles has been constructed and its behavior characterized in the laboratory. It has now been field tested and employed in several field studies to determine the exposure of individuals to radon progeny in the indoor environment. 22 refs., 1 fig., 1 tab.

Hopke, P.K.

1990-10-31

12

CARDIOVASCULAR EFFECTS OF ULTRAFINE CARBON PARTICLES IN HYPERTENSIVE RATS (SHR)  

EPA Science Inventory

Rationale: Epidemiological evidence suggests that ultrafine particles are associated with adverse cardiovascular effects, specifically in elderly individuals with preexisting cardiovascular disease. The objective of this study was (i) to assess cardiopulmonary responses in adult ...

13

In-cabin ultrafine particle dynamics  

NASA Astrophysics Data System (ADS)

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

Xu, Bin

14

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...

15

Polymer degradation and ultrafine particles - Potential inhalation hazards for astronauts  

NASA Technical Reports Server (NTRS)

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

Ferin, J.; Oberdoerster, G.

1992-01-01

16

Particle Deposition in Human Nasal Airway Replicas Manufactured by Different Methods. Part II: Ultrafine Particles  

Microsoft Academic Search

Information on the deposition of ultrafine particles in nasal airways is important for assessing the risks of exposure to airborne particulate matter and for understanding drug delivery implications for particles of this diameter. Nasal particle deposition is often studied using plastic replicas of nasal airways. Ultrafine particle deposition has been measured previously in replicas of nasal and upper airways that

James T. Kelly; Bahman Asgharian; Julia S. Kimbell; Brian A. Wong

2004-01-01

17

The persistence, transport and health effects of regional ultrafine particles  

NASA Astrophysics Data System (ADS)

Due to the multitude of health studies that have shown the ability of ultrafine particles (UFPs, DP < 100 nm) to penetrate deep into lung tissue, diffuse into the bloodstream, and eventually cause heart and lung disease, my thesis will focus on these effectively unmonitored airborne pollutants. UFPs are commonly detected near busy roadways and other high-temperature combustion sources in the form of heavy metals (copper, lead, zinc, iron) and toxic organics (benzo{a}pyrene, coronene). Studies of UFPs during the 1970s expressed a nucleic propensity for coagulation and growth. Because many of the UFPs studied were generated from heavy-duty diesel engines operating with ?0.3 wt % sulfur, the resulting sulfur-containing UFPs were hydrophilic and water vapor readily condensed on the generated nuclei. Due to their increased size, UFPs tend to settle out of air streams quickly; thus, limiting their impact regime to near-roadway influence and labeling them as local pollutants. By using highly size- and time-resolved impactors with TeflonRTM ultrafine after-filters (targeting DP < 90 nm), new evidence suggests the persistence of UFPs for greater periods of time and transport than previously predicted. Techniques developed during the Roseville rail yard study, refined during the Watt Ave/Arden Way study and applied across California's central valley have shown low levels of UFPs in a regional background. For cities in constrictive topography and meteorology (such as Bakersfield, Fresno and Los Angeles), winter inversions and stagnant weather can saturate the region with ultrafine heavy metals and carcinogenic organics, similar to the disasters during the middle of the last century.

Spada, Nicholas James

18

EFFECTS OF CARBON ULTRAFINE PARTICLES ON HUMAN AIRWAY EPITHELIAL CELLS  

EPA Science Inventory

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

19

Hygroscopic properties of ultrafine particles in coastal and forest environments  

NASA Astrophysics Data System (ADS)

The hygroscopic properties of recently produced ultrafine particles were measured in forestal and coastal environments using an Ultrafine Tandem Differential Mobility Analyser. The size range of the ambient aerosol particles that was investigated ranged from 8 nm to 30 nm in dry diameter. The measurements in a boreal forest site (SMEAR II station, Hyytiälä, Finland) showed that the growth factors during the days with production of ultrafine particles have a clear diurnal behavior. The minimum growth factor was ca. 1.12-1.13 and was obtained during nighttime. The maximum values were obtained between 13:00 and 16:00. The median values for the maximum growth factor for 10 nm dry diameter particles was 1.26 and for 20 nm dry size 1.28. The measurements in a coastal site (Mace Head station, Carna, Ireland) showed that the new particles produced during nucleation bursts were non- or slightly hygroscopic, with growth factor ca. 1.0-1.1 for 8 nm and 10 nm particles. The background ultrafine particles that were not connected with nucleation bursts were found to be more hygroscopic.

Hämeri, K.; Väkevä, M.

2000-08-01

20

CARDIOVASCULAR RESPONSES TO ULTRAFINE CARBON PARTICLE EXPOSURES IN RATS  

EPA Science Inventory

TD-02-042 (U. KODAVANTI) GPRA # 10108 Cardiovascular Responses to Ultrafine Carbon Particle Exposures in Rats. V. Harder1, B. Lentner1, A. Ziesenis1, E. Karg1, L. Ruprecht1, U. Kodavanti2, A. Stampfl3, J. Heyder1, H. Schulz1 GSF- Institute for Inhalation Biology1, I...

21

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

22

Fluxes of Ultrafine Particles Over and In a Deciduous Forest  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

23

Fine and ultrafine particle decay rates in multiple homes.  

PubMed

Human exposure to particles depends on particle loss mechanisms such as deposition and filtration. Fine and ultrafine particles (FP and UFP) were measured continuously over seven consecutive days during summer and winter inside 74 homes in Edmonton, Canada. Daily average air exchange rates were also measured. FP were also measured outside each home and both FP and UFP were measured at a central monitoring station. A censoring algorithm was developed to identify indoor-generated concentrations, with the remainder representing particles infiltrating from outdoors. The resulting infiltration factors were employed to determine the continuously changing background of outdoor particles infiltrating the homes. Background-corrected indoor concentrations were then used to determine rates of removal of FP and UFP following peaks due to indoor sources. About 300 FP peaks and 400 UFP peaks had high-quality (median R(2) value >98%) exponential decay rates lasting from 30 min to 10 h. Median (interquartile range (IQR)) decay rates for UFP were 1.26 (0.82-1.83) h(-1); for FP 1.08 (0.62-1.75) h(-1). These total decay rates included, on average, about a 25% contribution from air exchange, suggesting that deposition and filtration accounted for the major portion of particle loss mechanisms in these homes. Models presented here identify and quantify effects of several factors on total decay rates, such as window opening behavior, home age, use of central furnace fans and kitchen and bathroom exhaust fans, use of air cleaners, use of air conditioners, and indoor-outdoor temperature differences. These findings will help identify ways to reduce exposure and risk. PMID:24143863

Wallace, Lance; Kindzierski, Warren; Kearney, Jill; MacNeill, Morgan; Héroux, Marie-Ève; Wheeler, Amanda J

2013-11-19

24

Light scattering of ultrafine silica particles by VUV synchrotron radiation.  

PubMed

Vacuum ultraviolet (VUV) light scattering from ultrafine silica particles is studied with an aerosol instrument recently established at the Advanced Light Source (ALS) in Berkeley. Silica particles, size-selected by a differential mobility analyzer, are introduced into vacuum through a set of aerodynamic lenses to form a particle beam. The scattered photons from the crossing area of the VUV synchrotron beam and particle beam are detected with a rotatable VUV photon detector. The angular distributions of scattered photons (ADSP) originating from 70, 100, 200 nm diameter silica particles are measured with 145.9 and 118.1 nm synchrotron radiation. These angular distributions show strong forward scattering. The measured ADSPs are consistent with simulation of Mie scattering. The refractive indices of silica particles, 2.6 + 1.1i and 1.6 + 0.0001i for 118.1 and 145.9 nm, respectively, are obtained by fitting the measured ADSPs; the least average percentage deviations are 18% and 6%, respectively. The scattered fluxes at widely different wavelengths (visible versus VUV) also exhibit clear size sensitivity. Under comparable experimental conditions of photon fluxes and detection efficiencies, limits of particle size detection of 70 and 250 nm are obtained, respectively, when using 118.1 and 532 nm illumination. As anticipated, VUV scattering is a more sensitive probe for ultrafine particles, which will find application in detection of these ubiquitous species beyond the confines of a laboratory. PMID:15943434

Shu, Jinian; Wilson, Kevin R; Arrowsmith, Alan N; Ahmed, Musahid; Leone, Stephen R

2005-06-01

25

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

NASA Astrophysics Data System (ADS)

In the event of kinetic energy penetrator impact, survival personnel is exposed to the additional hazard stemming from ultrafine metallic particles, i.e. exposure, inhalation, and respiration of aerolized metals. Aerosol particle size distribution is an important parameter that influences aerosol transport and deposition processes. In order to have reliable quantitative measure of the aerosol particles generated under controlled impact conditions, an experimental set-up has been developed. Both non penetrating and penetrating impacts tests have been designed and performed with light gas-gun in chamber. During the impact, size distribution, total concentration and chemical composition of ultrafine particles have been measured and correlated with impact parameters (such as energy and velocity). In order to avoid measurement contamination, as a result of undesired participating materials, target and projectile have been made of the same metal and tests have been performed in clean environmental chamber. In this study the results relative to high purity copper are presented.

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

2011-06-01

26

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

Microsoft Academic Search

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

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

2004-01-01

27

Concentrations of ultrafine particles at a highway toll collection booth and exposure implications for toll collectors.  

PubMed

Research regarding the magnitude of ultrafine particle levels at highway toll stations is limited. This study measured ambient concentrations of ultrafine particles at a highway toll station from October 30 to November 1 and November 5 to November 6, 2008. A scanning mobility particle sizer was used to measure ultrafine particle concentrations at a ticket/cash tollbooth. Levels of hourly average ultrafine particles at the tollbooth were about 3-6 times higher than those in urban backgrounds, indicating that a considerable amount of ultrafine particles are exhausted from passing vehicles. A bi-modal size distribution pattern with a dominant mode at about <6 nm and a minor mode at about 40 nm was observed at the tollbooth. The high amounts of nanoparticles in this study can be attributed to gas-to-particle reactions in fresh fumes emitted directly from vehicles. The influences of traffic volume, wind speed, and relative humidity on ultrafine particle concentrations were also determined. High ambient concentrations of ultrafine particles existed under low wind speed, low relative humidity, and high traffic volume. Although different factors account for high ambient concentrations of ultrafine particles at the tollbooth, measurements indicate that toll collectors who work close to traffic emission sources have a high exposure risk. PMID:21071066

Cheng, Yu-Hsiang; Huang, Cheng-Hsiung; Huang, Hsiao-Lin; Tsai, Chuen-Jinn

2010-12-15

28

Process and apparatus for producing ultrafine explosive particles  

DOEpatents

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

McGowan, Michael J. (Martinsburg, WV)

1992-10-20

29

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

Microsoft Academic Search

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

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

2002-01-01

30

Spatio-temporal variation of urban ultrafine particle number concentrations  

NASA Astrophysics Data System (ADS)

Methods are needed to characterize short-term exposure to ultrafine particle number concentrations (UFP) for epidemiological studies on the health effects of traffic-related UFP. Our aims were to assess season-specific spatial variation of short-term (20-min) UFP within the city of Basel, Switzerland, and to develop hybrid models for predicting short-term median and mean UFP levels on sidewalks. We collected measurements of UFP for periods of 20 min (MiniDiSC particle counter) and determined traffic volume along sidewalks at 60 locations across the city, during non-rush hours in three seasons. For each monitoring location, detailed spatial characteristics were locally recorded and potential predictor variables were derived from geographic information systems (GIS). We built multivariate regression models to predict local UFP, using concurrent UFP levels measured at a suburban background station, and combinations of meteorological, temporal, GIS and observed site characteristic variables. For a subset of sites, we assessed the relationship between UFP measured on the sidewalk and at the nearby residence (i.e., home outdoor exposure on e.g. balconies). The average median 20-min UFP levels at street and urban background sites were 14,700 ± 9100 particles cm-3 and 9900 ± 8600 particles cm-3, respectively, with the highest levels occurring in winter and the lowest in summer. The most important predictor for all models was the suburban background UFP concentration, explaining 50% and 38% of the variability of the median and mean, respectively. While the models with GIS-derived variables (R2 = 0.61) or observed site characteristics (R2 = 0.63) predicted median UFP levels equally well, mean UFP predictions using only site characteristic variables (R2 = 0.62) showed a better fit than models using only GIS variables (R2 = 0.55). The best model performance was obtained by using a combination of GIS-derived variables and locally observed site characteristics (median: R2 = 0.66; mean: R2 = 0.65). The 20-min UFP concentrations measured at the sidewalk were strongly related (R2 = 0.8) to the concurrent 20-min residential UFP levels nearby. Our results indicate that median UFP can be moderately predicted by means of a suburban background site and GIS-derived traffic and land use variables. In areas and regions where large-scale GIS data are not available, the spatial distribution of traffic-related UFP may be assessed reasonably well by collecting on-site short-term traffic and land-use data.

Ragettli, Martina S.; Ducret-Stich, Regina E.; Foraster, Maria; Morelli, Xavier; Aguilera, Inmaculada; Basagaña, Xavier; Corradi, Elisabetta; Ineichen, Alex; Tsai, Ming-Yi; Probst-Hensch, Nicole; Rivera, Marcela; Slama, Rémy; Künzli, Nino; Phuleria, Harish C.

2014-10-01

31

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. PMID:22539559

Pesch, Beate

2012-01-01

32

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

PubMed

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

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

2012-07-01

33

Nanotoxicology: an emerging discipline evolving from studies of ultrafine particles.  

PubMed

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 biokinetic 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. PMID:16002369

Oberdörster, Günter; Oberdörster, Eva; Oberdörster, Jan

2005-07-01

34

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. ...

35

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

EPA Science Inventory

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

36

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

EPA Science Inventory

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

37

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

38

Magnetic properties of ultrafine cobalt ferrite particles L. D. Tung,a)  

E-print Network

Magnetic properties of ultrafine cobalt ferrite particles L. D. Tung,a) V. Kolesnichenko, D of a diluted system of ultrafine cobalt ferrite nanoparticles (d 3.3 nm). From the peak of the zero for cobalt ferrite, at 2 K, the reduced remanence Mr /Ms is equal to 0.46 which is close to the theoretical

Spinu, Leonard

39

[Ultrafine particles and effects on the body: review of the literature].  

PubMed

The International laws and the technology developments led to a situation where the current levels of environmental pollution are below those that existed at the beginning of the century: however, these pollution levels produce harmful effects to health linked to an increase in morbidity and mortality. Over the years the pollution has changed: following the transformation of heating, motor innovation and emissions reducing, has been a reduction in air concentration of some conventional pollutants (sulfur dioxide, carbon monoxide, benzene), while there wasn't a significant reduction of particulate air pollution. In this work have been questioned several electronic databases of scientific literature based on a selection algorithm that contains expressions for the following topics: "ultrafine particles", "effects on human health", "occupational and environmental exposure". We analyzed 200 articles, progressively reduced to 88, selected for keywords, year of publication and arguments; the main topics covered by the articles were related to chemical and physical UFP properties, UFP exposure, European legislation relating to the values of particle concentrations in the atmosphere, toxicokinetics and effects on various organs such as, in particular, the respiratory system, cardiovascular system, central nervous system and the intracellular mechanism of action. Analysis of the literature showed that ultrafine particles (PM0.1 aerodynamic diameter less than 0.1 microm) are more powerful than the coarse particle fraction (2.5-10 microm) and fine (0.1-2.5 microm) in inducing adverse effects to human health. Unfortunately, the study of mechanisms of action of these particles presents particular difficulties because of the large number of chemical and biological mechanisms that come into play in the body after exposure to ultrafine particles. PMID:20464974

Pedata, P; Garzillo, E M; Sannolo, N

2010-01-01

40

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

EPA Science Inventory

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

41

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

PubMed

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

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

2012-09-01

42

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

SciTech Connect

High particle collection efficiency in terms of particle weight/volume mg/m{sup 3} is well achieved by a conventional electrostatic precipitator (ESP). However, the collection efficiencies in terms of number density for the ultrafine (particle size between 0.01--0.1 {micro}m) or submicrometer particles by a conventional ESP are still relatively low. Therefore, it is necessary to improve the collection efficiency for ultrafine particles. In this paper, attempts have been made to improve the ultrafine particle collection efficiency by controlling dust loading, as well as using the short pulse energizations. The present version of the ESP consists of three sets of wire-plate-type electrodes. For the ESP under dc operation modes, experimental results show that the collection efficiency for dc applied voltage decreases with increasing dust loading when particle density is larger than 2.5 x 10{sup 10} particles/m{sup 3} due to inefficient collections of ultrafine particles. However, under pulse operating modes without dc bias, high particle collection efficiency for ultrafine particles was obtained, which is thought to be due to the enhancement of particle charging by electrons.

Zukeran, Akinori; Looy, P.C.; Chakrabarti, A.; Berezin, A.A.; Jayaram, S.; Cross, J.D.; Ito, Tairo; Chang, J.S.

1999-10-01

43

Ultrafine particle concentrations in and around idling school buses  

NASA Astrophysics Data System (ADS)

Unnecessary school bus idling increases children's exposure to diesel exhaust, but to what extent children are exposed to ultrafine particles (UFPs, diameter < 100 nm) in and around idling school buses remains unclear. This study employed nine school buses and simulated five scenarios by varying emissions source, wind direction, and window position. The purpose was to investigate the impact of idling on UFP number concentration and PM2.5 mass concentration inside and near school buses. Near the school buses, total particle number concentration increased sharply from engine off to engine on under all scenarios, by a factor of up to 26. The impact of idling on UFP number concentration inside the school buses depended on wind direction and window position: wind direction was important and statistically significant while the effect of window positions depended on wind direction. Under certain scenarios, idling increased in-cabin total particle number concentrations by a factor of up to 5.8, with the significant increase occurring in the size range of 10-30 nm. No significant change of in-cabin PM2.5 mass concentration was observed due to idling, regardless of wind direction and window position, indicating that PM2.5 is not a good indicator for primary diesel exhaust particle exposure. The deposition rates based on total particle number concentration inside school bus cabins varied between 1.5 and 5.0 h-1 across nine tested buses under natural convection conditions, lower than those of passenger cars but higher than those of indoor environments.

Zhang, Qunfang; Fischer, Heidi J.; Weiss, Robert E.; Zhu, Yifang

2013-04-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

45

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

46

ULTRAFINE PARTICLE DEPOSITION IN HEALTHY SUBJECTS VS. PATIENTS WTH COPD  

EPA Science Inventory

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

47

Personal Exposure to Ultrafine Particles and Oxidative DNA Damage  

PubMed Central

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

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

2005-01-01

48

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

49

ENHANCED TOXICITY OF CHARGED CARBON NANOTUBES AND ULTRAFINE CARBON BLACK PARTICLES  

EPA Science Inventory

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

50

Nature and evolution of ultrafine aerosol particles in the atmosphere  

NASA Astrophysics Data System (ADS)

Results of experimental and theoretical studies of a poorly understood phenomenon, an intense emission of ultrafine (nanometer) aerosols (ENA), are reviewed. In the English-language literature, this phenomenon is commonly referred to as a nucleation burst. ENA events have been observed on all the continents and throughout the depth of the troposphere, with the number of corresponding publications growing steadily. Intense and long-lasting ENA events have been studied more or less comprehensively and in full detail for Northern Europe, with 60 to 70% of observations taken in a forest area in the presence of snow cover and 10 to 20% in coastal marine areas. Most often, ENA events occur during spring and fall, with 95% of cases in the daytime and under sunny calm conditions, typical of anticyclones. In ENA events, the concentration of nanoparticles initially grows rapidly to values of 103-105 cm-3. One or two hours later, the so-called nuclei fraction with diameters D = 3-15 nm is produced. The appearance of the Aitken fraction D = 20-80 nm and the enlargement of aerosol particles inside the accumulation fraction D = 80-200 nm may occur during the following 4-6 h. Thus, the cycle of formation and growth of atmospheric aerosol particles in the size range from a few to hundreds of nanometers is reproduced over 6-8 h. A specific synoptic feature of ENA events over land is that they occur when the polar air is transported to measuring sites and the temperature difference between day and light is large. During ENA periods, the formation rate of condensation nuclei with a diameter of 100 nm increases 10-to 100-fold. Important factors of ENA genesis are the “aerosol” and “electric” states of the atmosphere. More intense ENA events occur at low concentrations of background aerosols in the presence of atmospheric ions of medium mobility with D = 2-3 nm. The international experiments ACE 1 and 2, BIOFOR 1, 2, and 3, ESUP 2000, QUEST, etc., have not yet provided any clear answers to the questions about physical and statistical dependences of the time of origin and duration of ENA and new particle characteristics on the solar and ionized radiation intensity and on the content of minor and biogenic gases. Models of new particle formation are discussed in the review.

Smirnov, V. V.

2006-12-01

51

Residential infiltration of fine and ultrafine particles in Edmonton  

NASA Astrophysics Data System (ADS)

Airborne indoor particles arise from both indoor sources and ambient particles that have infiltrated indoors. The intra-urban variability of infiltration factors (Finf) is a source of measurement error in epidemiological studies estimating exposure from a central site measurement, hence information on the within and between-home variability of Finf is useful to better characterize ambient PM exposure. The objective of this paper was to estimate magnitudes and predictors of daily residential infiltration factors (Finf) and ambient/non-ambient components of indoor ultrafine particle (UFP) and fine particle (FP) concentrations. FPs and UFPs were measured continuously for 7 consecutive days in 74 Edmonton homes in winter and summer 2010 (50 homes in each season). Simultaneous measurements of outdoor (near-home) FP and ambient (at a central site) UFP concentrations were also measured. Daily infiltration factors were estimated for each home; considerable variability was seen within and between homes. For FPs, seasonal-averaged Finf (the average of the 7 daily Finf estimates) ranged from 0.10 to 0.92 in winter (median = 0.30, n = 49) and 0.31 to 0.99 in summer (median = 0.68, n = 48). For UFPs, the seasonal-averaged Finf ranged from 0.08 to 0.47 across homes in winter (median = 0.21, n = 33 houses) and from 0.16 to 0.94 in summer (median = 0.57, n = 48). The higher median Finf in summer was attributed to a high frequency of open windows. Daily infiltration factors were also estimated based on the indoor/outdoor PM1 sulfur ratio. These estimates were poorly correlated with DustTrak-based FP infiltration factor estimates; the difference may be due to losses of volatile components on the PM1 filter samples. Generalized linear mixed models were used to identify variables significantly associated with Finf and the non-ambient component of indoor FP and UFP concentrations. Wind speed was consistently associated with Finf across all seasons for both FPs and UFPs. The use of an air cleaner was associated with reduced UFP infiltration factors in summer, suggesting a potential method of reducing infiltrated UFPs. Various cooking activities and smoking were associated with the non-ambient component of indoor FP and UFP concentrations. On average, the majority of indoor FPs were of ambient origin while the majority of UFPs were of indoor origin. In summer, more of the indoor FP and UFP concentrations were from ambient origin, compared to winter, due to the higher infiltration factors. The variability in FP and UFP Finf within and between homes may cause substantial exposure misclassification in epidemiological studies using only ambient measurements.

Kearney, Jill; Wallace, Lance; MacNeill, Morgan; Héroux, Marie-Eve; Kindzierski, Warren; Wheeler, Amanda

2014-09-01

52

Metrological assessment of a portable analyzer for monitoring the particle size distribution of ultrafine particles.  

PubMed

Adverse health effects caused by worker exposure to ultrafine particles have been detected in recent years. The scientific community focuses on the assessment of ultrafine aerosols in different microenvironments in order to determine the related worker exposure/dose levels. To this end, particle size distribution measurements have to be taken along with total particle number concentrations. The latter are obtainable through hand-held monitors. A portable particle size distribution analyzer (Nanoscan SMPS 3910, TSI Inc.) was recently commercialized, but so far no metrological assessment has been performed to characterize its performance with respect to well-established laboratory-based instruments such as the scanning mobility particle sizer (SMPS) spectrometer. The present paper compares the aerosol monitoring capability of the Nanoscan SMPS to the laboratory SMPS in order to evaluate whether the Nanoscan SMPS is suitable for field experiments designed to characterize particle exposure in different microenvironments. Tests were performed both in a Marple calm air chamber, where fresh diesel particulate matter and atomized dioctyl phthalate particles were monitored, and in microenvironments, where outdoor, urban, indoor aged, and indoor fresh aerosols were measured. Results show that the Nanoscan SMPS is able to properly measure the particle size distribution for each type of aerosol investigated, but it overestimates the total particle number concentration in the case of fresh aerosols. In particular, the test performed in the Marple chamber showed total concentrations up to twice those measured by the laboratory SMPS-likely because of the inability of the Nanoscan SMPS unipolar charger to properly charge aerosols made up of aggregated particles. Based on these findings, when field test exposure studies are conducted, the Nanoscan SMPS should be used in tandem with a condensation particle counter in order to verify and correct the particle size distribution data. PMID:24817159

Stabile, Luca; Cauda, Emanuele; Marini, Sara; Buonanno, Giorgio

2014-08-01

53

The role of organic condensation on ultrafine particle growth during nucleation events  

NASA Astrophysics Data System (ADS)

A new aerosol dynamics model (DMANx) has been developed that simulates the aerosol size/composition distribution and includes the condensation of organic vapors on nanoparticles through the implementation of the recently developed Volatility Basis Set framework. Simulations were performed for Hyytiala (Finland) and Finokalia (Greece), two locations with different organic sources where detailed measurements were available to constrain the new model. We investigate the effect of condensation of organics and chemical aging reactions of secondary organic aerosol (OA) on ultrafine particle growth and particle number concentration. This work highlights the importance of the pathways of oxidation of biogenic volatile organic compounds and the production of extremely low-volatility organics. At Hyytiala, organic condensation dominates the growth process of new particles. The low-volatility secondary OA contributes to particle growth during the early growth stage, but after a few hours most of the growth is due to semi-volatile secondary OA. At Finokalia, simulations show that organics have a complementary role to new particle growth contributing 45% to the total mass of new particles. Condensation of organics increases the number concentration of particles that can act as CCN (N100) by 13% at Finokalia and 25% at Hyytiala. The sensitivity of our results to the surface tension used is discussed.

Patoulias, D.; Fountoukis, C.; Riipinen, I.; Pandis, S. N.

2014-12-01

54

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

EPA Science Inventory

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

55

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

EPA Science Inventory

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

56

The exposure to coarse, fine and ultrafine particle emissions from concrete mixing, drilling and cutting activities.  

PubMed

Building activities generate coarse (PM10?10?m), fine (PM2.5?2.5?m) and ultrafine particles (<100nm) making it necessary to understand both the exposure levels of operatives on site and the dispersion of ultrafine particles into the surrounding environment. This study investigates the release of particulate matter, including ultrafine particles, during the mixing of fresh concrete (incorporating Portland cement with Ground Granulated Blastfurnace Slag, GGBS or Pulverised Fuel Ash, PFA) and the subsequent drilling and cutting of hardened concrete. Particles were measured in the 5-10,000nm size range using a GRIMM particle spectrometer and a fast response differential mobility spectrometer (DMS50). The mass concentrations of PM2.5-10 fraction contributed ?52-64% of total mass released. The ultrafine particles dominated the total particle number concentrations (PNCs); being 74, 82, 95 and 97% for mixing with GGBS, mixing with PFA, drilling and cutting, respectively. Peak values measured during the drilling and cutting activities were 4 and 14 times the background. Equivalent emission factors were calculated and the total respiratory deposition dose rates for PNCs for drilling and cutting were 32.97±9.41×10(8)min(-1) and 88.25±58.82×10(8)min(-1). These are a step towards establishing number and mass emission inventories for particle exposure during construction activities. PMID:25068443

Azarmi, Farhad; Kumar, Prashant; Mulheron, Mike

2014-08-30

57

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

EPA Science Inventory

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

58

Fine and ultrafine particles in 20 French dwellings related to time-activity Olivier Ramalho1,*  

E-print Network

Particles are a major pollutant in the indoor environment with contributions from both outdoor and indoor survey 2003- 2005 conducted by the Observatory of Indoor Air Quality (OQAI) (Kirchner et al., 2007 (OPC, dust monitor model 1.108, Grimm GMBH). In a subset of 10 dwellings, ultrafine particles (UFP

Paris-Sud XI, Université de

59

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

60

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

61

Ultrafine SrM particles with high coercivity by chemical coprecipitation  

NASA Astrophysics Data System (ADS)

Ultrafine (˜80 nm), single domain Sr hexaferrite (SrM) particles with Sm additives were produced by chemical coprecipitation. The effects of the Sm 3+/Sr 2+ ratio on the crystallography and magnetic properties of Sm doped SrM ultrafine particles have been investigated. A very high coercivity of 528 kA/m (6635 Oe) with a magnetisation at 1100 kA/m of 63.07 J/T kg was obtained for the sample of Sm3+/ Sr2+= {1}/{14} calcined at 850°C for 2 h in air.

Wang, J. F.; Ponton, C. B.; Harris, I. R.

2002-04-01

62

Formation and Growth of Ultrafine Particles from Secondary Anthropogenic Sources in Bakersfield  

NASA Astrophysics Data System (ADS)

There is extensive evidence that ultrafine particles (Dp<100 nm) have adverse effects on human health. In this study, physical and chemical properties of ultrafine aerosol particles are investigated at a polluted urban site in Bakersfield, California. The analysis is based on measurements during the CalNex campaign 15 May to 29 June in 2010. Aerosol measurements in this study include mainly particle number size distributions provided by a Scanning Mobility Particle Sizer (SMPS) 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 during the campaign and the events had a very regular pattern. A nucleation mode centered at 10-20 nm appeared in early morning and was observed to grow up to 40-100 nm throughout the day. Most of the growth events were regional, representing horizontal scales of at least 100 km. Microphysical modeling and size-resolved HR-ToF-AMS concentrations show that organic components dominated the particle growth in the ultrafine mode, and sulfate provided only a minor contribution to the growth. The ultrafine mass was largely dominated by organics (83%) and was in general at maximum during the afternoon, indicating the importance of photochemistry. Whereas elemental carbon and the AMS tracer m/z 57 for hydrocarbon-like organic aerosol (HOA) peaked in early morning during rush hour, indicative of primary emissions, particle number concentration peaked in the afternoon. This is interpreted as a result of new particle formation. Potentially important parameters for both growth and new particle formation, as concentrations of oxidizers and different organic and inorganic vapors, have been investigated.

Ahlm, L.; Russell, L. M.; Liu, S.; Day, D. A.; Weber, R.; Gentner, D. R.; Goldstein, A. H.; Keutsch, F. N.; VandenBoer, T. C.; Markovic, M. Z.; Murphy, J. G.

2011-12-01

63

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

64

Ultrafine particle emission characteristics of diesel engine by on-board and test bench measurement.  

PubMed

This study investigated the emission characteristics of ultrafine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of (0.56-8.35) x 10(8) cm(-3). The on-board measurement results illustrated that the ultrafine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 x 10(6) cm(-3) and 2.7 x 10(7) cm(-3) under decelerating and idling operations and as high as 5.0 x 10(8) cm(-3) under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a "U" shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds. PMID:23534231

Huang, Cheng; Lou, Diming; Hu, Zhiyuan; Tan, Piqiang; Yao, Di; Hu, Wei; Li, Peng; Ren, Jin; Chen, Changhong

2012-01-01

65

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

66

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

EPA Science Inventory

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

67

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

EPA Science Inventory

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

68

PULMONARY AND CARDIAC GENE EXPRESSION FOLLOWING ACUTE ULTRAFINE CARBON PARTICLE INHALATION IN HYPERTENSIVE RATS  

EPA Science Inventory

Inhalation of ultrafine carbon particles (ufCP) causes cardiac physiological changes without marked pulmonary injury or inflammation. We hypothesized that acute ufCP exposure of 13 months old Spontaneously Hypertensive (SH) rats will cause differential effects on the lung and hea...

69

Combustion of PTFE: The effects of gravity on ultrafine particle generation  

NASA Technical Reports Server (NTRS)

The objective of this project is to obtain an understanding of the effect of gravity on the toxicity of ultrafine particle and gas phase materials produced when fluorocarbon polymers are thermally degraded or burned. The motivation for the project is to provide a basic technical foundation on which policies for spacecraft health and safety with regard to fire and polymers can be formulated.

McKinnon, Thomas; Todd, Paul; Oberdorster, Gunter

1996-01-01

70

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

PubMed

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

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

2013-05-21

71

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

72

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. PMID:15735058

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; Oberdörster, Günter

2005-01-01

73

Method for the production of ultrafine particles by electrohydrodynamic micromixing  

DOEpatents

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

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

2001-01-01

74

Environmental and health impacts of fine and ultrafine metallic particles: assessment of threat scores.  

PubMed

This study proposes global threat scores to prioritize the harmfulness of anthropogenic fine and ultrafine metallic particles (FMP) emitted into the atmosphere at the global scale. (Eco)toxicity of physicochemically characterized FMP oxides for metals currently observed in the atmosphere (CdO, CuO, PbO, PbSO(4), Sb(2)O(3), and ZnO) was assessed by performing complementary in vitro tests: ecotoxicity, human bioaccessibility, cytotoxicity, and oxidative potential. Using an innovative methodology based on the combination of (eco)toxicity and physicochemical results, the following hazard classification of the particles is proposed: CdCl2~CdO>CuO>PbO>ZnO>PbSO(4)>Sb(2)O(3). Both cadmium compounds exhibited the highest threat score due to their high cytotoxicity and bioaccessible dose, whatever their solubility and speciation, suggesting that cadmium toxicity is due to its chemical form rather than its physical form. In contrast, the Sb(2)O(3) threat score was the lowest due to particles with low specific area and solubility, with no effects except a slight oxidative stress. As FMP physicochemical properties reveal differences in specific area, crystallization systems, dissolution process, and speciation, various mechanisms may influence their biological impact. Finally, this newly developed and global approach could be widely used in various contexts of pollution by complex metal particles and may improve risk management. PMID:24959986

Goix, Sylvaine; Lévêque, Thibaut; Xiong, Tian-Tian; Schreck, Eva; Baeza-Squiban, Armelle; Geret, Florence; Uzu, Gaëlle; Austruy, Annabelle; Dumat, Camille

2014-08-01

75

Observations of ultra-fine particles above a deciduous forest in Denmark  

NASA Astrophysics Data System (ADS)

We report physical particle size distribution and chemical composition data over a Beech forest in Denmark during May and June of 2004 with a focus on four days characterized by high concentrations of ultra-fine particles. Highest number concentrations of sub-30 nm particles were observed when net radiation >300 W m-2 and ambient particle surface area <100 ?m2 cm-3. The 10-30 nm particles show growth rates of 1.5-4.5 nm hr-1 and are comprised predominantly of ammonium, sulfate and associated water.

Pryor, S. C.; Barthelmie, R. J.; Prip, H.; Sørensen, L. L.

2005-03-01

76

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

EPA Science Inventory

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

77

Number size distribution of fine and ultrafine fume particles from various welding processes.  

PubMed

Studies in the field of environmental epidemiology indicate that for the adverse effect of inhaled particles not only particle mass is crucial but also particle size is. Ultrafine particles with diameters below 100 nm are of special interest since these particles have high surface area to mass ratio and have properties which differ from those of larger particles. In this paper, particle size distributions of various welding and joining techniques were measured close to the welding process using a fast mobility particle sizer (FMPS). It turned out that welding processes with high mass emission rates (manual metal arc welding, metal active gas welding, metal inert gas welding, metal inert gas soldering, and laser welding) show mainly agglomerated particles with diameters above 100 nm and only few particles in the size range below 50 nm (10 to 15%). Welding processes with low mass emission rates (tungsten inert gas welding and resistance spot welding) emit predominantly ultrafine particles with diameters well below 100 nm. This finding can be explained by considerably faster agglomeration processes in welding processes with high mass emission rates. Although mass emission is low for tungsten inert gas welding and resistance spot welding, due to the low particle size of the fume, these processes cannot be labeled as toxicologically irrelevant and should be further investigated. PMID:23028013

Brand, Peter; Lenz, Klaus; Reisgen, Uwe; Kraus, Thomas

2013-04-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

79

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

PubMed Central

For traffic-related pollutants like ultrafine particles (UFP, Dp < 100 nm), a significant fraction of overall exposure occurs within or close to the transit microenvironment. Therefore, understanding exposure to these pollutants in such microenvironments is crucial to accurately assessing overall UFP exposure. The aim of this study was to develop models for predicting in-cabin UFP concentrations if roadway concentrations are known, taking into account vehicle characteristics, ventilation settings, driving conditions and air exchange rates (AER). Particle concentrations and AER were measured in 43 and 73 vehicles, respectively, under various ventilation settings and driving speeds. Multiple linear regression (MLR) and generalized estimating equation (GEE) regression models were used to identify and quantify the factors that determine inside-to-outside (I/O) UFP ratios and AERs across a full range of vehicle types and ages. AER was the most significant determinant of UFP I/O ratios, and was strongly influenced by ventilation setting (recirculation or outside air intake). Inclusion of ventilation fan speed, vehicle age or mileage, and driving speed explained greater than 79% of the variability in measured UFP I/O ratios. PMID:23888122

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

2013-01-01

80

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

81

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

Microsoft Academic Search

Increasing evidence has demonstrated toxic effects of vehicular emitted ultrafine particles (UFPs, diameter < 100 nm), with the highest human exposure usually occurring on and near roadways. Children are particularly at risk due to immature respiratory systems and faster breathing rates. In this study, children’s exposure to in-cabin air pollutants, especially UFPs, was measured inside four diesel-powered school buses. Two 1990 and two

Qunfang Zhang; Yifang Zhu

2010-01-01

82

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

83

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

84

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

85

Size-resolved deposition rates for ultrafine and submicrometer particles in a residential housing unit.  

PubMed

We estimated the size-resolved particle deposition rates for the ultrafine and submicrometer particles using a nonlinear regression method with unknown particle background concentrations during nonsourced period following a controlled sourced period in a well-mixed residential environment. A dynamic adjustment method in conjunction with the constant injection of tracer gas was used to maintain the air exchange rate at three target levels across the range of 0.61-1.24 air change per hour (ACH). Particle deposition was found to be highly size dependent with rates ranging from 0.68 ± 0.10 to 5.03 ± 0.20 h(-1) (mean ± s.e.). Our findings also suggest that the effect of air exchange on the particle deposition under enhanced air mixing was relatively small when compared to both the strong influence of size-dependent deposition mechanisms and the effects of mechanical air mixing by fans. Nonetheless, the significant association between air exchange and particle deposition rates for a few size categories indicated potential influence of air exchange on particle deposition. In the future, the proposed approach can be used to explore the separate or composite effects between air exchange and air mixing on particle deposition rates, which will contribute to improved assessment of human exposure to ultrafine and submicrometer particles. PMID:25126897

Lee, Wan-Chen; Wolfson, Jack M; Catalano, Paul J; Rudnick, Stephen N; Koutrakis, Petros

2014-09-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

87

Ultrafine particles, and PM 2.5 generated from cooking in homes  

NASA Astrophysics Data System (ADS)

Exposure to airborne particulate matters (PM) emitted during cooking can lead to adverse health effects. An understanding of the exposure to PM during cooking at home provides a foundation for the quantification of possible health risks. The concentrations of airborne particles covering the ultrafine (14.6-100 nm) and accumulation mode (100-661.2 nm) size ranges and PM 2.5 (airborne particulate matters smaller than 2.5 ?m in diameter) during and after cooking activities were measured in 12 naturally ventilated, non-smoking homes in Hong Kong, covering a total of 33 cooking episodes. The monitored homes all practiced Chinese-style cooking. Cooking elevated the average number concentrations of ultrafine particles (UFPs) and accumulation mode particles (AMPs) by 10 fold from the background level in the living room and by 20-40 fold in the kitchen. PM 2.5 mass concentrations went up to the maximum average of about 160 ?g m -3 in the kitchen and about 60 ?g m -3 in the living room. Cooking emitted particles dispersed quickly from the kitchen to the living room indicating that the health impact is not limited to occupants in the kitchen. Particle number and mass concentrations remained elevated for 90 min in the kitchen and for 60 min in the living room after cooking. Particles in cooking emissions were mainly in the ultrafine size range in terms of the number count while AMPs contributed to at least 60% of the surface area concentrations in the kitchen and 73% in the living room. This suggests that AMPs could still be a major health concern since the particle surface area concentration is suggested to have a more direct relationship with inhalation toxicity than with number concentration. Particle number concentration (14.6-661.2 nm) in the living room was about 2.7 times that in the outdoor environment, suggesting that better ventilation could help reduce exposure.

Wan, Man-Pun; Wu, Chi-Li; Sze To, Gin-Nam; Chan, Tsz-Chun; Chao, Christopher Y. H.

2011-11-01

88

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. PMID:16079062

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

2005-01-01

89

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. PMID:16079063

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

2005-01-01

90

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

91

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

92

Ultrafine particles cause cytoskeletal dysfunctions in macrophages: role of intracellular calcium  

PubMed Central

Background Particulate air pollution is reported to cause adverse health effects in susceptible individuals. Since most of these particles are derived form combustion processes, the primary composition product is carbon with a very small diameter (ultrafine, less than 100 nm in diameter). Besides the induction of reactive oxygen species and inflammation, ultrafine particles (UFP) can cause intracellular calcium transients and suppression of defense mechanisms of alveolar macrophages, such as impaired migration or phagocytosis. Methods In this study the role of intracellular calcium transients caused by UFP was studied on cytoskeleton related functions in J774A.1 macrophages. Different types of fine and ultrafine carbon black particles (CB and ufCB, respectively), such as elemental carbon (EC90), commercial carbon (Printex 90), diesel particulate matter (DEP) and urban dust (UD), were investigated. Phagosome transport mechanisms and mechanical cytoskeletal integrity were studied by cytomagnetometry and cell viability was studied by fluorescence microscopy. Macrophages were exposed in vitro with 100 and 320 ?g UFP/ml/million cells for 4 hours in serum free medium. Calcium antagonists Verapamil, BAPTA-AM and W-7 were used to block calcium channels in the membrane, to chelate intracellular calcium or to inhibit the calmodulin signaling pathways, respectively. Results Impaired phagosome transport and increased cytoskeletal stiffness occurred at EC90 and P90 concentrations of 100 ?g/ml/million cells and above, but not with DEP or UD. Verapamil and W-7, but not BAPTA-AM inhibited the cytoskeletal dysfunctions caused by EC90 or P90. Additionally the presence of 5% serum or 1% bovine serum albumin (BSA) suppressed the cytoskeletal dysfunctions. Cell viability showed similar results, where co-culture of ufCB together with Verapamil, W-7, FCS or BSA produced less cell dead compared to the particles only. PMID:16202162

Möller, Winfried; Brown, David M; Kreyling, Wolfgang G; Stone, Vicki

2005-01-01

93

Measurement and capture of fine and ultrafine particles from a pilot-scale pulverized coal combustor with an electrostatic precipitator  

SciTech Connect

Experiments were carried out in a pilot-scale pulverized coal combustor at the Energy and Environmental Research Center (EERC) burning a Powder River Basin (PRB) subbituminous coal. A scanning mobility particle sizer (SMPS) and an electrical low-pressure impactor (ELPI) were used to measure the particle size distributions (PSDs) in the range of 17 nm to 10 m at the inlet and outlet of the electrostatic precipitator (ESP). At the ESP inlet, a high number concentration of ultrafine particles was found, with the peak at approximately 75 nm. A trimodal PSD for mass concentration was observed with the modes at approximately 80-100 nm, 1-2 {mu}m, and 10 {mu}m. The penetration of ultrafine particles through the ESP increased dramatically as particle size decreased below 70 nm, attributable to insufficient or partial charging of the ultrafine particles. Injection of nanostructured fine-particle sorbents for capture of toxic metals in the flue gas caused high penetration of the ultrafine particles through the ESP. The conventional ESP was modified to enhance charging using soft X-ray irradiation. A slipstream of flue gas was introduced from the pilot-scale facility and passed through this modified ESP. Enhancement of particle capture was observed with the soft X-ray irradiation when moderate voltages were used in the ESP, indicating more efficient charging of fine particles. 32 refs., 5 figs., 1 tab.

Ying Li; Achariya Suriyawong; Michael Daukoru; Ye Zhuang; Pratim Biswas [Washington University, St. Louis, MO (United States). Aerosol and Air Quality Research Laboratory

2009-05-15

94

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

PubMed

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

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

2003-01-01

95

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

96

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

SciTech Connect

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

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

2006-12-31

97

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

PubMed

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

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

2014-02-01

98

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

PubMed

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

Dong, Shuofei; Yao, Maosheng

2010-11-01

99

Ultrafine Particles from Traffic Emissions and Children's Health (UPTECH) in Brisbane, Queensland (Australia): Study Design and Implementation.  

PubMed

Ultrafine particles are particles that are less than 0.1 micrometres (µm) in diameter. Due to their very small size they can penetrate deep into the lungs, and potentially cause more damage than larger particles. The Ultrafine Particles from Traffic Emissions and Children's Health (UPTECH) study is the first Australian epidemiological study to assess the health effects of ultrafine particles on children's health in general and peripheral airways in particular. The study is being conducted in Brisbane, Australia. Continuous indoor and outdoor air pollution monitoring was conducted within each of the twenty five participating school campuses to measure particulate matter, including in the ultrafine size range, and gases. Respiratory health effects were evaluated by conducting the following tests on participating children at each school: spirometry, forced oscillation technique (FOT) and multiple breath nitrogen washout test (MBNW) (to assess airway function), fraction of exhaled nitric oxide (FeNO, to assess airway inflammation), blood cotinine levels (to assess exposure to second-hand tobacco smoke), and serum C-reactive protein (CRP) levels (to measure systemic inflammation). A pilot study was conducted prior to commencing the main study to assess the feasibility and reliably of measurement of some of the clinical tests that have been proposed for the main study. Air pollutant exposure measurements were not included in the pilot study. PMID:25648226

Ezz, Wafaa Nabil; Mazaheri, Mandana; Robinson, Paul; Johnson, Graham R; Clifford, Samuel; He, Congrong; Morawska, Lidia; Marks, Guy B

2015-01-01

100

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

101

In-cabin commuter exposure to ultrafine particles on Los Angeles freeways.  

PubMed

Worldwide people are exposed to toxic ultrafine particles (UFP, with diameters (dp) less than 100 nm) and nanoparticles (NP, dp < 50 nm) under a variety of circumstances. To date, very limited information is available on human exposure to freshly emitted UFP and NP while traveling on major roads and freeways. We report in-cabin and outdoor measurements of particle number concentration and size distributions while driving three vehicles on Los Angeles freeways. Particle number concentrations and size distributions were measured under different vehicle ventilation settings. When the circulation fan was set to on, with substantial external air intake, outside changes in particle counts caused corresponding in-cabin changes approximately 30-60 s later, indicating an maximal air exchange rate of about 120-60 h(-1). Maximum in-cabin protection (approximately 85%) was obtained when both fan and recirculation were on. In-cabin and outdoor particle size distributions in the 7.9-217 nm range were observed to be mostly bimodal, with the primary peak occurring at 10-30 nm and the secondary at 50-70 nm. The vehicle's manufacture-installed particle filter offered an in-cabin protection of about 50% for particles in the 7-40 nm size range and 20-30% for particles in the 40 to approximately 200 nm size range. For an hour daily commute exposure, the in-vehicle microenvironment contributes approximately 10-50% of people's daily exposure to UFP from traffic. PMID:17438754

Zhu, Yifang; Eiguren-Fernandez, Arantzazu; Hinds, William C; Miguel, Antonio H

2007-04-01

102

Production of Ultrafine, High-purity Ceramic Powders Using the US Bureau of Mines Developed Turbomill  

NASA Technical Reports Server (NTRS)

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

Hoyer, Jesse L.

1993-01-01

103

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

EPA Science Inventory

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

104

Indoor ultrafine particle exposures and home heating systems: A cross-sectional survey of Canadian homes during the winter months  

Microsoft Academic Search

Exposure to airborne particulate matter has a negative effect on respiratory health in both children and adults. Ultrafine particle (UFP) exposures are of particular concern owing to their enhanced ability to cause oxidative stress and inflammation in the lungs. In this investigation, our objective was to examine the contribution of home heating systems (electric baseboard heaters, wood stoves, forced-air oil\\/natural

Scott Weichenthal; Andre Dufresne; Claire Infante-Rivard; Lawrence Joseph

2007-01-01

105

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

PubMed

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

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

2011-03-15

106

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

PubMed Central

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

2014-01-01

107

Characteristics of ultrafine particle sources and deposition rates in primary school classrooms  

NASA Astrophysics Data System (ADS)

The aim of this work was to investigate changes in particle number concentration (PNC) within naturally ventilated primary school classrooms arising from local sources either within or adjacent to the classrooms. We quantify the rate at which ultrafine particles were emitted either from printing, grilling, heating or cleaning activities and the rate at which the particles were removed by both deposition and air exchange processes. At each of 25 schools in Brisbane, Australia, two weeks of measurements of PNC and CO2 were taken both outdoors and in the two classrooms. Bayesian regression modelling was employed in order to estimate the relevant rates and analyse the relationship between air exchange rate (AER), particle infiltration and the deposition rates of particle generated from indoor activities in the classrooms. During schooling hours, grilling events at the school tuckshop as well as heating and printing in the classrooms led to indoor PNCs being elevated by a factor of more than four, with emission rates of (2.51 ± 0.25) × 1011 p min-1, (8.99 ± 6.70) × 1011 p min-1 and (5.17 ± 2.00) × 1011 p min-1, respectively. During non-school hours, cleaning events elevated indoor PNC by a factor of above five, with an average emission rate of (2.09 ± 6.30) × 1011 p min-1. Particles were removed by both air exchange and deposition; chiefly by ventilation when AER > 0.7 h-1 and by deposition when AER < 0.7 h-1.

Laiman, Rusdin; He, Congrong; Mazaheri, Mandana; Clifford, Samuel; Salimi, Farhad; Crilley, Leigh R.; Megat Mokhtar, Megat Azman; Morawska, Lidia

2014-09-01

108

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

PubMed

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

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

2011-11-01

109

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

110

Traffic-generated emissions of ultrafine particles from pavement-tire interface  

NASA Astrophysics Data System (ADS)

In a road simulator study, a significant source of sub-micrometer fine particles produced by the road-tire interface was observed. Since the particle size distribution and source strength is dependent on the type of tire used, it is likely that these particles largely originate from the tires, and not the road pavement. The particles consisted most likely of mineral oils from the softening filler and fragments of the carbon-reinforcing filler material (soot agglomerates). This identification was based on transmission electron microscopy studies of collected ultrafine wear particles and on-line thermal treatment using a thermodesorber. The mean particle number diameters were between 15-50 nm, similar to those found in light duty vehicle (LDV) tail-pipe exhaust. A simple box model approach was used to estimate emission factors in the size interval 15-700 nm. The emission factors increased with increasing vehicle speed, and varied between 3.7×10 11 and 3.2×10 12 particles vehicle -1 km -1 at speeds of 50 and 70 km h -1. This corresponds to between 0.1-1% of tail-pipe emissions in real-world emission studies at similar speeds from a fleet of LDV with 95% gasoline and 5% diesel-fueled cars. The emission factors for particles originating from the road-tire interface were, however, similar in magnitude to particle number emission factors from liquefied petroleum gas-powered vehicles derived in test bench studies in Australia 2005. Thus the road-tire interface may be a significant contributor to particle emissions from ultraclean vehicles.

Dahl, Andreas; Gharibi, Arash; Swietlicki, Erik; Gudmundsson, Anders; Bohgard, Mats; Ljungman, Anders; Blomqvist, Göran; Gustafsson, Mats

111

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

PubMed

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

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

2011-09-15

112

Nasal deposition of ultrafine particles in human volunteers and its relationship to airway geometry  

SciTech Connect

Very large and very small particles most often deposit in the nasal airways. Studies in airway models provide large data sets with which to evaluate the deposition mechanism, while in vivo deposition data are needed to validate results obtained with nasal models. Four adult male, nonsmoking, healthy human volunteers (ages 36-57 yr) participated in this study. Deposition was measured in each subject at constant flow rates of 4, 7.5, 10, and 20 L min{sup -1}. Monodisperse silver particles (5, 8, and 20 nm) and polystyrene latex particles (50 and 100 nm) were used. Bach subject held his breath for 30-60 sec, during which time, the aerosol was drawn through the nasal airway and exhausted through a mouth tube. Aerosol concentrations in the intake and exhaust air were measured by an ultrafine condensation particle counter. The deposition efficiency in the nasal airway was calculated taking into account particle losses in the mask, mouth tube, and transport lines. Our results were consistent with the turbulent diffusional deposition model previously established from studies using nasal airway casts. 21 refs., 12 figs., 3 tabs.

Cheng, Y.S.; Yeh, H.C.; Guilmette, R.A. [Inhalation Toxicology Research Inst., Albuquerque, NM (United States); Simpson, S.Q. [Univ. of New Mexico, Albuquerque, NM (United States); Cheng, K.H.; Swift, D.L. [Johns Hopkins Univ., Baltimore, MD (United States)

1996-10-01

113

Soft-X-Ray-Enhanced Electrostatic Precipitation for Protection against Inhalable Allergens, Ultrafine Particles, and Microbial Infections  

PubMed Central

Protection of the human lung from infectious agents, allergens, and ultrafine particles is difficult with current technologies. High-efficiency particulate air (HEPA) filters remove airborne particles of >0.3 ?m with 99.97% efficiency, but they are expensive to maintain. Electrostatic precipitation has been used as an inexpensive approach to remove large particles from airflows, but it has a collection efficiency minimum in the submicrometer size range, allowing for a penetration window for some allergens and ultrafine particles. Incorporating soft X-ray irradiation as an in situ component of the electrostatic precipitation process greatly improves capture efficiency of ultrafine particles. Here we demonstrate the removal and inactivation capabilities of soft-X-ray-enhanced electrostatic precipitation technology targeting infectious agents (Bacillus anthracis, Mycobacterium bovis BCG, and poxviruses), allergens, and ultrafine particles. Incorporation of in situ soft X-ray irradiation at low-intensity corona conditions resulted in (i) 2-fold to 9-fold increase in capture efficiency of 200- to 600-nm particles and (ii) a considerable delay in the mean day of death as well as lower overall mortality rates in ectromelia virus (ECTV) cohorts. At the high-intensity corona conditions, nearly complete protection from viral and bacterial respiratory infection was afforded to the murine models for all biological agents tested. When optimized for combined efficient particle removal with limited ozone production, this technology could be incorporated into stand-alone indoor air cleaners or scaled for installation in aircraft cabin, office, and residential heating, ventilating, and air-conditioning (HVAC) systems. PMID:23263945

Kettleson, Eric M.; Schriewer, Jill M.; Buller, R. Mark L.

2013-01-01

114

Transformation of Ultrafine Titanium Dioxide Particles from Rutile to Anatase at Negatively Charged Colloid Surfaces  

NASA Astrophysics Data System (ADS)

The phase transition of TiO 2from rutile to anatase has not been reported below the transition temperature from anatase to rutile. This work reports the new observation that ultrafine rutile-type particles are transformed into anatase by contacting the strongly negatively charged colloid particles such as V 2O 5· nH 2O, MoO 3, and H 2WO 4· nH 2O. The weakly negatively charged particles of silica and montmorillonite did not change the structure. More active Nb 2O 5· nH 2O and Ta 2O 5· nH 2O reacted chemically with TiO 2to produce new compounds. Conversely, anatase-type TiO 2was changed into rutile by contacting with HCl solution. From these facts it is concluded that chloride ions at the interface affect to form the rutile-type TiO 2, although anatase is thermodynamically stable at low temperatures. It is concluded that the surface field of the strongly negatively charged crystalline particles in an acidic condition eases the TiO 2article to crystallize into a thermodynamically stable one.

Kittaka, Shigeharu; Matsuno, Kohsaku; Takahara, Shuichi

1997-09-01

115

Emission characteristics of ultrafine particles and volatile organic compounds in a commercial printing center.  

PubMed

Laser printers are one of the common indoor equipment in schools, offices, and various other places. Laser printers have recently been identified as a potential source of indoor air pollution. This study examines the characteristics of ultrafine particles (UFPs, diameter <100 nm) and volatile organic compounds (VOCs) emitted from laser printers housed in a commercial printing center. The results indicated that apart from the printer type, the age of printers, and the number of pages printed, the characteristics of UFPs emitted from printers also depend on indoor ventilation conditions. It was found that at reduced ventilation rates of indoor air, there was a rise in the number concentration of UFPs in the printing center. Interestingly, the contribution of UFPs to the total number of submicrometer-sized particles was observed to be higher at a sampling point far away from the printer than the one in the immediate vicinity of the printer. Black carbon (BC) measurements showed a good correlation (rs = 0.82) with particles in the size range of 100-560 nm than those with diameters less than 100 nm (rs = 0.33 for 50-100 nm, and rs = -0.19 for 5.6-50 nm particles). Measurements of VOCs in the printing center showed high levels of m-, o-, and p-xylene, styrene, and ethylbenzenes during peak hours of printing. Although toluene was found in higher levels, its concentration decreased during peak hours compared to those during nonoperating hours of the printing center. PMID:22168093

Betha, Raghu; Selvam, Valliappan; Blake, Donald R; Balasubramanian, Rajasekhar

2011-11-01

116

Ultrafine particles generated from coloring with scented markers in the presence of ozone.  

PubMed

High concentrations of ultrafine particles (UFPs) have been previously reported during school art activities. This is possibly due to secondary organic aerosols (SOAs) formed from reactions between ozone and volatile organic compounds emitted from art products. Four brands of markers, three scented and one unscented, were tested inside a stainless steel chamber at eight different ozone concentrations between 0 and 300 ppb. Out of the 32 tested markers, only the lemon- and orange-scented markers from one brand reacted with ozone to form UFPs. Limonene, pinene, and several other terpenes were identified as ingredients of ink in SOA-forming markers. Coloring with one lemon-scented marker for 1 min without ozone generated on average approximately 26 ± 4 ppb of limonene inside the chamber. At 150 ppb ozone, using one lemon marker for 1 min formed on average 7.7 × 10(10) particles. The particle size distribution indicated an initial mode of 15 nm which grew to 40 nm. At 50 ppb ozone and below, no significant SOA formation occurred. The number of particles formed is moderately correlated with the mass of ink used (R(2)  = 0.68). Based on these data, scented markers are not likely a strong source of SOA under normal indoor ozone levels. PMID:24547888

Fung, C-C D; Shu, S; Zhu, Y

2014-10-01

117

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

118

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

119

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. PMID:21995556

2011-01-01

120

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

EPA Science Inventory

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

121

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

122

Ultrafine Angelica gigas powder normalizes ovarian hormone levels and has antiosteoporosis properties in ovariectomized rats: particle size effect.  

PubMed

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. PMID:23039111

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

2012-10-01

123

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. PMID:23039111

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

2012-01-01

124

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

2013-10-15

125

Aerosol-computational fluid dynamics modeling of ultrafine and black carbon particle emission, dilution, and growth near roadways  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

126

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

127

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

128

Estimates of HVAC filtration efficiency for fine and ultrafine particles of outdoor origin  

NASA Astrophysics Data System (ADS)

This work uses 194 outdoor particle size distributions (PSDs) from the literature to estimate single-pass heating, ventilating, and air-conditioning (HVAC) filter removal efficiencies for PM2.5 and ultrafine particles (UFPs: <100 nm) of outdoor origin. The PSDs were first fitted to tri-modal lognormal distributions and then mapped to size-resolved particle removal efficiency of a wide range of HVAC filters identified in the literature. Filters included those with a minimum efficiency reporting value (MERV) of 5, 6, 7, 8, 10, 12, 14, and 16, as well as HEPA filters. We demonstrate that although the MERV metric defined in ASHRAE Standard 52.2 does not explicitly account for UFP or PM2.5 removal efficiency, estimates of filtration efficiency for both size fractions increased with increasing MERV. Our results also indicate that outdoor PSD characteristics and assumptions for particle density and typical size-resolved infiltration factors (in the absence of HVAC filtration) do not drastically impact estimates of HVAC filter removal efficiencies for PM2.5. The impact of these factors is greater for UFPs; however, they are also somewhat predictable. Despite these findings, our results also suggest that MERV alone cannot always be used to predict UFP or PM2.5 removal efficiency given the various size-resolved removal efficiencies of different makes and models, particularly for MERV 7 and MERV 12 filters. This information improves knowledge of how the MERV designation relates to PM2.5 and UFP removal efficiency for indoor particles of outdoor origin. Results can be used to simplify indoor air quality modeling efforts and inform standards and guidelines.

Azimi, Parham; Zhao, Dan; Stephens, Brent

2014-12-01

129

Personal day-time exposure to ultrafine particles in different microenvironments.  

PubMed

In order to assess the personal exposure to ultrafine particles (UFP) during individual day-time activities and to investigate the impact of different microenvironments on exposure, we measured personal exposure to particle number concentrations (PNC), a surrogate for UFP, among 112 non-smoking participants in Augsburg, Germany over a nearly two-year period from March 2007 to December 2008. We obtained 337 personal PNC measurements from 112 participants together with dairies of their activities and locations. The measurements lasted on average 5.5h and contained on average 330 observations. In addition, ambient PNC were measured at an urban background stationary monitoring site. Personal PNC were highly variable between measurements (IQR of mean: 11780-24650cm(-3)) and also within a single measurement. Outdoor personal PNC in traffic environments were about two times higher than in non-traffic environments. Higher indoor personal PNC were associated with activities like cooking, being in a bistro or exposure to passive smoking. Overall, personal and stationary PNC were weakly to moderately correlated (r<0.41). Personal PNC were much higher than stationary PNC in traffic (ratio: 1.5), when shopping (ratio: 2.4), and indoors with water vapor (ratio: 2.5). Additive mixed models were applied to predict personal PNC by participants' activities and locations. Traffic microenvironments were significant determinants for outdoor personal PNC. Being in a bistro, passive smoking, and cooking contributed significantly to an increased indoor personal PNC. PMID:25458919

Gu, Jianwei; Kraus, Ute; Schneider, Alexandra; Hampel, Regina; Pitz, Mike; Breitner, Susanne; Wolf, Kathrin; Hänninen, Otto; Peters, Annette; Cyrys, Josef

2015-03-01

130

Small particles disrupt postnatal airway development  

PubMed Central

Increasing numbers of epidemiologic studies associate air pollution exposure in children with decreased lung function development. The objective of this study was to examine the effects of exposure to combustion-generated fine [230 and 212 nm number mean aerodynamic particle diameter (NMAD)] to ultrafine (73 nm NMAD) particles differing in elemental (EC) and organic (OC) carbon content on postnatal airway development in rats. Neonatal Sprague-Dawley rats were exposed from postnatal day 7 through 25, and lung function and airway architecture were evaluated 81 days of age. In a separate group of rats, cell proliferation was examined after a single particle exposure at 7 days of age. Early life exposure to 73 nm high OC/EC particles altered distal airway architecture and resulted in subtle changes in lung mechanics. Early life exposure to 212 nm high OC/EC particles did not alter lung architecture but did alter lung mechanics in a manner suggestive of central airway changes. In contrast, early life exposure to 230 nm low OC/EC particles did not alter lung architecture or mechanics. A single 6-h exposure to 73 nm high OC/EC particle decreased airway cell proliferation, whereas 212 nm high OC/EC particles increased it and 230 nm low OC/EC particles did not. The early life exposure to ultrafine, high OC/EC particles results in persistent alterations in distal airway architecture that is characterized by an initial decrease in airway cell proliferation. PMID:20634362

Lee, DongYoub; Wallis, Chris; Schelegle, Edward S.; Van Winkle, Laura S.; Plopper, Charles G.; Fanucchi, Michelle V.; Kumfer, Ben; Kennedy, Ian M.; Chan, Jackie K. W.

2010-01-01

131

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

NASA Astrophysics Data System (ADS)

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

1989-07-01

132

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. PMID:15471724

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

2004-01-01

133

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

NASA Astrophysics Data System (ADS)

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

Zhang, Qunfang; Zhu, Yifang

2010-01-01

134

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

135

ALADINA - an unmanned research aircraft for observing vertical and horizontal distributions of ultrafine particles within the atmospheric boundary layer  

NASA Astrophysics Data System (ADS)

This paper presents the unmanned research aircraft Carolo P360 "ALADINA" (Application of Light-weight Aircraft for Detecting IN-situ Aerosol) for investigating the horizontal and vertical distribution of ultrafine particles in the atmospheric boundary layer (ABL). It has a wingspan of 3.6 m, a maximum take-off weight of 25 kg and is equipped with aerosol instrumentation and meteorological sensors. A first application of the system, together with the unmanned research aircraft MASC (Multi-Purpose Airborne Carrier) of the Eberhard-Karls University of Tübingen (EKUT), is described. As small payload for ALADINA, two condensation particle counters (CPC) and one optical particle counter (OPC) were miniaturized by re-arranging the vital parts and composing them in a space saving way in the front compartment of the airframe. The CPCs are improved concerning the lower detection threshold and the response time. Each system was characterized in the laboratory and calibrated with test aerosols. The CPCs are operated with two different lower detection threshold diameters of 6 and 18 nm. The amount of ultrafine particles, which is an indicator for new particle formation, is derived from the difference in number concentrations of the two CPCs. Turbulence and thermodynamic structure of the boundary layer are described by measurements of fast meteorological sensors that are mounted at the aircraft nose. A first demonstration of ALADINA and a feasibility study were conducted in Melpitz near Leipzig, Germany, at the Global Atmosphere Watch (GAW) station of the Leibniz Institute for Tropospheric Research (TROPOS) on two days in October 2013. There, various ground-based instruments are installed for long-term atmospheric monitoring. The ground-based infrastructure provides valuable additional background information to embed the flights in the continuous atmospheric context and is used for validation of the airborne results. The development of the boundary layer, derived from backscatter signals of a portable Raman lidar POLLYXT, allows a quick overview of the current vertical structure of atmospheric particles. Ground-based aerosol number concentrations are consistent with the results from flights in heights of a few meters. In addition, a direct comparison of ALADINA aerosol data and ground-based aerosol data, sampling the air at the same location, shows comparable values. MASC was operated simultaneously with complementary flight patterns. It is equipped with the same meteorological instruments that offer the possibility to determine turbulent fluxes. Therefore additional information about meteorological conditions was collected in the lowest part of the atmosphere. Vertical profiles up to 1000 m altitude indicate a high variability with distinct layers of aerosol especially for the small particles of a few nanometers in diameter. Particle bursts were observed on one day during the boundary layer development in the morning.

Altstädter, B.; Platis, A.; Wehner, B.; Scholtz, A.; Lampert, A.; Wildmann, N.; Hermann, M.; Käthner, R.; Bange, J.; Baars, H.

2014-12-01

136

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

137

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

PubMed Central

Background Particulate matter, especially ultrafine particles (UFPs), may cause health effects through generation of oxidative stress, with resulting damage to DNA and other macromolecules. Objective We investigated oxidative damage to DNA and related repair capacity in peripheral blood mononuclear cells (PBMCs) during controlled exposure to urban air particles with assignment of number concentration (NC) to four size modes with average diameters of 12, 23, 57, and 212 nm. Design Twenty-nine healthy adults participated in a randomized, two-factor cross-over study with or without biking exercise for 180 min and with exposure to particles (NC 6169-15362/cm3) or filtered air (NC 91-542/cm3) for 24 hr. Methods The levels of DNA strand breaks (SBs), oxidized purines as formamidopyrimidine DNA glycolase (FPG) sites, and activity of 7,8-dihydro-8-oxoguanine-DNA glycosylase (OGG1) in PBMCs were measured by the Comet assay. mRNA levels of OGG1, nucleoside diphosphate linked moiety X-type motif 1 (NUDT1), and heme oxygenase-1 (HO1) were determined by real-time reverse transcriptase–polymerase chain reaction. Results Exposure to UFPs for 6 and 24 hr significantly increased the levels of SBs and FPG sites, with a further insignificant increase after physical exercise. The OGG1 activity and expression of OGG1, NUDT1, and HO1 were unaltered. There was a significant dose–response relationship between NC and DNA damage, with the 57-nm mode as the major contributor to effects. Concomitant exposure to ozone, nitrogen oxides, and carbon monoxide had no influence. Conclusion Our results indicate that UFPs, especially the 57-nm soot fraction from vehicle emissions, causes systemic oxidative stress with damage to DNA and no apparent compensatory up-regulation of DNA repair within 24 hr. PMID:17687444

Bräuner, Elvira Vaclavik; Forchhammer, Lykke; Møller, Peter; Simonsen, Jacob; Glasius, Marianne; Wåhlin, Peter; Raaschou-Nielsen, Ole; Loft, Steffen

2007-01-01

138

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

139

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

140

An hourly regression model for ultrafine particles in a near-highway urban area.  

PubMed

Estimating ultrafine particle number concentrations (PNC) near highways for exposure assessment in chronic health studies requires models capable of capturing PNC spatial and temporal variations over the course of a full year. The objectives of this work were to describe the relationship between near-highway PNC and potential predictors, and to build and validate hourly log-linear regression models. PNC was measured near Interstate 93 (I-93) in Somerville, MA using a mobile monitoring platform driven for 234 h on 43 days between August 2009 and September 2010. Compared to urban background, PNC levels were consistently elevated within 100-200 m of I-93, with gradients impacted by meteorological and traffic conditions. Temporal and spatial variables including wind speed and direction, temperature, highway traffic, and distance to I-93 and major roads contributed significantly to the full regression model. Cross-validated model R(2) values ranged from 0.38 to 0.47, with higher values achieved (0.43 to 0.53) when short-duration PNC spikes were removed. The model predicts highest PNC near major roads and on cold days with low wind speeds. The model allows estimation of hourly ambient PNC at 20-m resolution in a near-highway neighborhood. PMID:24559198

Patton, Allison P; Collins, Caitlin; Naumova, Elena N; Zamore, Wig; Brugge, Doug; Durant, John L

2014-03-18

141

Modeling ultrafine particle growth at a pine forest site influenced by anthropogenic pollution during BEACHON-RoMBAS 2011  

NASA Astrophysics Data System (ADS)

Formation and growth of ultrafine particles is crudely represented in chemistry-climate models, contributing to uncertainties in aerosol composition, size distribution, and aerosol effects on cloud condensation nuclei (CCN) concentrations. Measurements of ultrafine particles, their precursor gases, and meteorological parameters were performed in a ponderosa pine forest in the Colorado Front Range in July-August 2011, and were analyzed to study processes leading to small particle burst events (PBEs) which were characterized by an increase in the number concentrations of ultrafine 4-30 nm diameter size particles. These measurements suggest that PBEs were associated with the arrival at the site of anthropogenic pollution plumes midday to early afternoon. During PBEs, number concentrations of 4-30 nm diameter particles typically exceeded 104 cm-3, and these elevated concentrations coincided with increased SO2 and monoterpene concentrations, and led to a factor-of-2 increase in CCN concentrations at 0.5% supersaturation. The PBEs were simulated using the regional WRF-Chem model, which was extended to account for ultrafine particle sizes starting at 1 nm in diameter, to include an empirical activation nucleation scheme in the planetary boundary layer, and to explicitly simulate the subsequent growth of Aitken particles (10-100 nm) by condensation of organic and inorganic vapors. The updated model reasonably captured measured aerosol number concentrations and size distribution during PBEs, as well as ground-level CCN concentrations. Model results suggest that sulfuric acid originating from anthropogenic SO2 triggered PBEs, and that the condensation of monoterpene oxidation products onto freshly nucleated particles contributes to their growth. The simulated growth rate of ~ 3.4 nm h-1 for 4-40 nm diameter particles was comparable to the measured average value of 2.3 nm h-1. Results also suggest that the presence of PBEs tends to modify the composition of sub-20 nm diameter particles, leading to a higher mass fraction of sulfate aerosols. Sensitivity simulations suggest that the representation of nucleation processes in the model largely influences the predicted number concentrations and thus CCN concentrations. We estimate that nucleation contributes 67% of surface CCN at 0.5% supersaturation in this pine forest environment.

Cui, Y. Y.; Hodzic, A.; Smith, J. N.; Ortega, J.; Brioude, J.; Matsui, H.; Levin, E. J. T.; Turnipseed, A.; Winkler, P.; de Foy, B.

2014-10-01

142

Partitioning of Black Carbon between ultrafine and fine particle modes in an urban airport vs. urban background environment  

NASA Astrophysics Data System (ADS)

In this work, we characterize the Black Carbon (BC) aerosol in an urban airport vs. urban background environment with the objective to evaluate when and how the ultrafine BC dominates the bulk aerosol. Aerosol optical and microphysical properties were measured in a Mediterranean urban area (Rome) at sites impacted by BC sources including fossil fuels (FF), and biomass burning (BB). Experimental BC data were interpreted through measurement-constrained simulations of BC microphysics and optical properties. A 'scheme' to separate the ultrafine BC was experimented on the basis of the relation found between changes in the BC partitioning between Aitken and accumulation mode particles, and relevant changes in particle size distribution and optical properties of the bulk aerosol. This separation scheme, applied to experimental data, proved useful to reveal the impact of airport and road traffic emissions. Findings may have important atmospheric implications. The experimented scheme can help separating different BC sources (FF, BB, 'aged' BC) when BC size distributions may be very difficult to obtain (satellite, columnar observations, routine monitoring). Indeed, separating the ultrafine BC from the fine BC may provide significant benefits in addressing BC impact on air quality and climate.

Costabile, F.; Angelini, F.; Barnaba, F.; Gobbi, G. P.

2015-02-01

143

A branch scale analytical model for predicting the vegetation collection efficiency of ultrafine particles  

NASA Astrophysics Data System (ADS)

The removal of ultrafine particles (UFP) by vegetation is now receiving significant attention given their role in cloud physics, human health and respiratory related diseases. Vegetation is known to be a sink for UFP, prompting interest in their collection efficiency. A number of models have tackled the UFP collection efficiency of an isolated leaf or a flat surface; however, up-scaling these theories to the ecosystem level has resisted complete theoretical treatment. To progress on a narrower scope of this problem, simultaneous experimental and theoretical investigations are carried out at the “intermediate” branch scale. Such a scale retains the large number of leaves and their interaction with the flow without the heterogeneities and added geometric complexities encountered within ecosystems. The experiments focused on the collection efficiencies of UFP in the size range 12.6-102 nm for pine and juniper branches in a wind tunnel facility. Scanning mobility particle sizers were used to measure the concentration of each diameter class of UFP upstream and downstream of the vegetation branches thereby allowing the determination of the UFP vegetation collection efficiencies. The UFP vegetation collection efficiency was measured at different wind speeds (0.3-1.5 m s-1), packing density (i.e. volume fraction of leaf or needle fibers; 0.017 and 0.040 for pine and 0.037, 0.055 for juniper), and branch orientations. These measurements were then used to investigate the performance of a proposed analytical model that predicts the branch-scale collection efficiency using conventional canopy properties such as the drag coefficient and leaf area density. Despite the numerous simplifications employed, the proposed analytical model agreed with the wind tunnel measurements mostly to within 20%. This analytical tractability can benefit future air quality and climate models incorporating UFP.

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

2012-05-01

144

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

PubMed Central

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 to manganese (Mn) oxide UFPs (30 nm; ~ 500 ?g/m3) with either both nostrils patent or the right nostril occluded. We analyzed Mn in lung, liver, olfactory bulb, and other brain regions, and we performed gene and protein analyses. Results After 12 days of exposure with both nostrils patent, Mn concentrations in the olfactory bulb increased 3.5-fold, whereas lung Mn concentrations doubled; there were also increases in striatum, frontal cortex, and cerebellum. Lung lavage analysis showed no indications of lung inflammation, whereas increases in olfactory bulb tumor necrosis factor-? mRNA (~ 8-fold) and protein (~ 30-fold) were found after 11 days of exposure and, to a lesser degree, in other brain regions with increased Mn levels. Macrophage inflammatory protein-2, glial fibrillary acidic protein, and neuronal cell adhesion molecule mRNA were also increased in olfactory bulb. With the right nostril occluded for a 2-day exposure, Mn accumulated only in the left olfactory bulb. Solubilization of the Mn oxide UFPs was < 1.5% per day. Conclusions We conclude that the olfactory neuronal pathway is efficient for translocating inhaled Mn oxide as solid UFPs to the central nervous system and that this can result in inflammatory changes. We suggest that despite differences between human and rodent olfactory systems, this pathway is relevant in humans. PMID:16882521

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

2006-01-01

145

Gene expression profile in circulating mononuclear cells after exposure to ultrafine carbon particles  

PubMed Central

Context Exposure to particulate matter (PM) is associated with systemic health effects, but the cellular and molecular mechanisms are unclear. Objective We hypothesized that, if circulating mononuclear cells play an important role in mediating systemic effects of PM, they would show gene expression changes following exposure. Materials and methods Peripheral blood samples were collected before (0 hour) and at 24 hours after exposure from healthy subjects who participated in previous controlled exposures to ultrafine carbon particles (UFP, 50 ?g/m3) or filtered air (FA)(n = 3 each). RNA from mononuclear cell fraction (>85% lymphocytes) was extracted, amplified and hybridized to Affymetrix HU133 plus 2 microarrays. Results We identified 1713 genes (UFP 24 hours vs. FA 0 and 24 hours, p < 0.05, FDR 0.01). The top 10 upregulated genes (fold) were CDKN1C (1.86), ZNF12 (1.83), SRGAP2 (1.82), FYB (1.79), LSM14B (1.79), CD93 (1.76), NCSTN (1.70), DUSP6 (1.69), TACC1 (1.68) and H2AFY (1.68). Upregulation of CDKN1C and SRGAP2 was confirmed by RT-PCR using samples from additional 5 subjects exposed to FA and UFP. We entered 1020 genes with a ratio >1.1 or

Huang, Yuh-Chin T.; Schmitt, Michael; Yang, Zhonghui; Que, Loretta G.; Stewart, Judith C.; Frampton, Mark W.; Devlin, Robert B.

2013-01-01

146

Modeling Population Exposure to Ultrafine Particles in a Major Italian Urban Area  

PubMed Central

Average daily ultrafine particles (UFP) exposure of adult Milan subpopulations (defined on the basis of gender, and then for age, employment or educational status), in different exposure scenarios (typical working day in summer and winter) were simulated using a microenvironmental stochastic simulation model. The basic concept of this kind of model is that time-weighted average exposure is defined as the sum of partial microenvironmental exposures, which are determined by the product of UFP concentration and time spent in each microenvironment. In this work, environmental concentrations were derived from previous experimental studies that were based on microenvironmental measurements in the city of Milan by means of personal or individual monitoring, while time-activity patterns were derived from the EXPOLIS study. A significant difference was observed between the exposures experienced in winter (W: 28,415 pt/cm3) and summer (S: 19,558 pt/cm3). Furthermore, simulations showed a moderate difference between the total exposures experienced by women (S: 19,363 pt/cm3; W: 27,623 pt/cm3) and men (S: 18,806 pt/cm3; W: 27,897 pt/cm3). In addition, differences were found as a function of (I) age, (II) employment status and (III) educational level; accordingly, the highest total exposures resulted for (I) 55–59 years old people, (II) housewives and students and (III) people with higher educational level (more than 10 years of scholarity). Finally, significant differences were found between microenvironment-specific exposures. PMID:25321878

Spinazzè, Andrea; Cattaneo, Andrea; Peruzzo, Carlo; Cavallo, Domenico M.

2014-01-01

147

Different exposure of infants and adults to ultrafine particles in the urban area of Barcelona.  

PubMed

Air pollutants have been linked with a number of adverse health effects. Children are especially sensitive, particularly when they get close to the exhaust emissions of the vehicles on the street. The objective of this study was to measure the different exposure of infants and adults to ultrafine particles (UFP) as a surrogate marker of air pollution and of risk of deleterious health effects. Two different portable P-TRAK® were used to measure simultaneously exposure to UFPs at different heights, one corresponding to the height of an infant in a stroller (0.55 m) and the other one to the height of the face of an adult pedestrian (1.70 m). Measurements were taken on three different streets with high traffic density in Barcelona, in 10 consecutive days during spring, with two sampling sessions of 1 h each day, moving afoot and taking into account temperature, humidity, and wind speed. Fifty-two thousand and eight (52,008) paired values were obtained, and the results showed about 10 % higher levels of UFP concentration at 0.55 m (48,198?±?25,296 pt/cm(3)) compared to 1.70 m (43,151?±?22,517 pt/cm(3)). Differences between working and nonworking days were observed. Concentration patterns and variation by days of the week and time periods were related to traffic intensity. This study revealed that infants transported by stroller in urban areas are more exposed to air pollution than walking adults. As infants are more vulnerable and UFP have more effects on their health, measures should be taken to protect this population when it is transported in the street. PMID:25433547

Garcia-Algar, Oscar; Canchucaja, Lizzeth; d'Orazzio, Valentina; Manich, Andrea; Joya, Xavier; Vall, Oriol

2015-01-01

148

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

PubMed

A major constituent of urban air pollution is diesel exhaust, a complex mixture of gases, chemicals, and particles. Recent evidence suggests that exposure to air pollution can increase the risk of a fatal stroke, cause cerebrovascular damage, and induce neuroinflammation and oxidative stress that may trigger neurodegenerative diseases, such as Parkinson's disease. The specific aim of this study was to determine whether ultrafine diesel exhaust particles (DEPs), the particle component of exhaust from diesel engines, can induce oxidative stress and effect dopamine metabolism in PC-12 cells. After 24 h exposure to DEPs of 200 nm or smaller, cell viability, ROS and nitric oxide (NO(2)) generation, and levels of dopamine (DA) and its metabolites, (dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA)), were evaluated. Results indicated cell viability was not significantly changed by DEP exposure. However, ROS showed dramatic dose-dependent changes after DEP exposure (2.4 fold increase compared to control at 200 ?g/mL). NO(2) levels were also dose-dependently increased after DEP exposure. Although not in a dose-dependent manner, upon DEP exposure, intracellular DA levels were increased while DOPAC and HVA levels decreased when compared to control. Results suggest that ultrafine DEPs lead to dopamine accumulation in the cytoplasm of PC-12 cells, possibly contributing to ROS formation. Further studies are warranted to elucidate this mechanism. PMID:24705343

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

2014-05-01

149

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...

150

On-road and laboratory investigations on non-exhaust ultrafine particles from the interaction between the tire and road pavement under braking conditions  

NASA Astrophysics Data System (ADS)

We investigated the physical and chemical characteristics of non-exhaust ultrafine particles from on-road driving and laboratory measurements using a mobile sampling vehicle. The on-road driving and laboratory measurements during constant speed conditions revealed no enhancement of ultrafine particles. Under braking events, the total number concentrations of tire particles (TPs) sampled 90 mm above the road surface was 6 times higher with broader mode diameters when compared to 40 mm above the road surface. In contrast to braking events, under cornering conditions, the total number concentrations of TPs sampled 40 mm above the road surface were 50 times higher relative to 90 mm above the road surface. From the morphological and elemental analyses, it is likely that the ultrafine particles generated from the interaction between the tire and the road surface under braking conditions might originated from sulfur-containing materials or anti-oxidants which are contained in TPs, and/or graphite and solid lubricants which are mainly present in brake particles (BPs). However, Zn which was a distinguishing elemental marker of tire wear particles didn't show in EDS spectra. Further research would be required as to the exact emission source of ultrafine particles.

Kwak, Jihyun; Lee, Sunyoup; Lee, Seokhwan

2014-11-01

151

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

152

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

PubMed

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

Zhu, Yifang; Zhang, Qunfang

2014-03-01

153

Ultrafine particles from electric appliances and cooking pans: experiments suggesting desorption/nucleation of sorbed organics as the primary source.  

PubMed

Ultrafine particles are observed when metal surfaces, such as heating elements in electric appliances, or even empty cooking pans, are heated. The source of the particles has not been identified. We present evidence that particles >10 nm are not emitted directly from the heating elements or the metal surfaces. Using repeated heating of an electric burner, several types of cooking pans, and a steam iron, the increase in the number of particles (>10 nm) can be reduced to 0. After the devices are exposed to indoor air for several hours or days, subsequent heating results in renewed particle production, suggesting that organic matter has sorbed on their surfaces. Also, after a pan has been heated to the point that no increase in particles is observed, washing with detergent results in copious production of particles the next time the pan is heated. These observations suggest that detergent residue and organics sorbed from indoor air are the sources of the particles. We hypothesize that organic compounds are thermally desorbed from the hot surface as gaseous molecules; as they diffuse from the hot air near the pan into cooler air, selected compounds exceed their saturation concentration and nucleation occurs. PMID:25250820

Wallace, L A; Ott, W R; Weschler, C J

2014-09-24

154

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

PubMed Central

Background Diabetes may confer an increased risk for the cardiovascular health effects of particulate air pollution, but few human clinical studies of air pollution have included people with diabetes. Ultrafine particles (UFP, ?100 nm in diameter) have been hypothesized to be an important component of particulate air pollution with regard to cardiovascular health effects. Methods 17 never-smoker subjects 30–60 years of age, with stable type 2 diabetes but otherwise healthy, inhaled either filtered air (0–10 particles/cm3) or elemental carbon UFP (~107 particles/cm3, ~50 ug/m3, count median diameter 32 nm) by mouthpiece, for 2 hours at rest, in a double-blind, randomized, crossover study design. A digital 12-lead electrocardiogram (ECG) was recorded continuously for 48 hours, beginning 1 hour prior to exposure. Results Analysis of 5-minute segments of the ECG during quiet rest showed reduced high-frequency heart rate variability with UFP relative to air exposure (p?=?0.014), paralleled by non-significant reductions in time-domain heart rate variability parameters. In the analysis of longer durations of the ECG, we found that UFP exposure increased the heart rate relative to air exposure. During the 21- to 45-hour interval after exposure, the average heart rate increased approximately 8 beats per minute with UFP, compared to 5 beats per minute with air (p?=?0.045). There were no UFP effects on cardiac rhythm or repolarization. Conclusions Inhalation of elemental carbon ultrafine particles alters heart rate and heart rate variability in people with type 2 diabetes. Our findings suggest that effects may occur and persist hours after a single 2-hour exposure. PMID:25028096

2014-01-01

155

Novel technologies for the production of ultrafine coal liquefaction catalysts  

SciTech Connect

Unusual materials processing technologies offer the potential for forming ultrafine iron-bearing particles suitable for coal liquefaction catalysis. Two such technologies currently under development at the Pacific Northwest Laboratory are the rapid expansion of supercritical fluid solutions (RESS) process and the precipitation of ultrafine particles in reverse micelle solutions. The RESS process involves expansion of dilute solutions through a small orifice from pressures and temperatures at which they exist as supercritical fluids, to ambient or near ambient conditions such that the post-expansion solvent exists solely in the gaseous phase. The abrupt drop in solvent density and the resulting solute particle nucleation and growth which occur during a RESS expansion promote formation of an ultrafine aerosol consisting of nanometer to micrometer scale solid solute particles. Precipitation of iron sulfides and iron oxides in reverse micelle systems as an alternative route to nanometer scale particle formation is also discussed.

Matson, D.W.; Linehan, J.C.; Fulton, J.L.; Bean, R.M.

1991-10-01

156

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

Microsoft Academic Search

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

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

2010-01-01

157

Spatial variation of ultrafine particles and black carbon in two cities: Results from a short-term measurement campaign.  

PubMed

Recently, short-term monitoring campaigns have been carried out to investigate the spatial variation of air pollutants within cities. Typically, such campaigns are based on short-term measurements at relatively large numbers of locations. It is largely unknown how well these studies capture the spatial variation of long term average concentrations. The aim of this study was to evaluate the within-site temporal and between-site spatial variation of the concentration of ultrafine particles (UFPs) and black carbon (BC) in a short-term monitoring campaign. In Amsterdam and Rotterdam (the Netherlands) measurements of number counts of particles larger than 10nm as a surrogate for UFP and BC were performed at 80 sites per city. Each site was measured in three different seasons of 2013 (winter, spring, summer). Sites were selected from busy urban streets, urban background, regional background and near highways, waterways and green areas, to obtain sufficient spatial contrast. Continuous measurements were performed for 30min per site between 9 and 16h to avoid traffic spikes of the rush hour. Concentrations were simultaneously measured at a reference site to correct for temporal variation. We calculated within- and between-site variance components reflecting temporal and spatial variations. Variance ratios were compared with previous campaigns with longer sampling durations per sample (24h to 14days). The within-site variance was 2.17 and 2.44 times higher than the between-site variance for UFP and BC, respectively. In two previous studies based upon longer sampling duration much smaller variance ratios were found (0.31 and 0.09 for UFP and BC). Correction for temporal variation from a reference site was less effective for the short-term monitoring campaign compared to the campaigns with longer duration. Concentrations of BC and UFP were on average 1.6 and 1.5 times higher at urban street compared to urban background sites. No significant differences between the other site types and urban background were found. The high within to between-site concentration variances may result in the loss of precision and low explained variance when average concentrations from short-term campaigns are used to develop land use regression models. PMID:25486637

Klompmaker, Jochem O; Montagne, Denise R; Meliefste, Kees; Hoek, Gerard; Brunekreef, Bert

2015-03-01

158

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

159

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

PubMed Central

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

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

2013-01-01

160

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

161

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

162

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

SciTech Connect

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

Not Available

1989-07-18

163

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

164

Lead and cadmium phytoavailability and human bioaccessibility for vegetables exposed to soil or atmospheric pollution by process ultrafine particles.  

PubMed

When plants are exposed to airborne particles, they can accumulate metals in their edible portions through root or foliar transfer. There is a lack of knowledge on the influence of plant exposure conditions on human bioaccessibility of metals, which is of particular concern with the increase in urban gardening activities. Lettuce, radish, and parsley were exposed to metal-rich ultrafine particles from a recycling factory via field atmospheric fallouts or polluted soil. Total lead (Pb) and cadmium (Cd) concentrations in of the edible plant parts and their human bioaccessibility were measured, and Pb translocation through the plants was studied using Pb isotopic analysis. The Pb and Cd bioaccessibility measured for consumed parts of the different polluted plants was significantly higher for root exposure (70% for Pb and 89% for Cd in lettuce) in comparison to foliar exposure (40% for Pb and 69% for Cd in lettuce). The difference in metal bioaccessibility could be linked to the metal compartmentalization and speciation changes in relation to exposure conditions. Metal nature strongly influences the measured bioaccessibility: Cd presents higher bioaccessibility in comparison to Pb. In the case of foliar exposure, a significant translocation of Pb from leaves toward the roots was observed. To conclude, the type of pollutant and the method of exposure significantly influences the phytoavailability and human bioaccessibility of metals, especially in relation to the contrasting phenomena involved in the rhizosphere and phyllosphere. The conditions of plant exposure must therefore be taken into account for environmental and health risk assessment. PMID:25603245

Xiong, Tiantian; Leveque, Thibault; Shahid, Muhammad; Foucault, Yann; Mombo, Stéphane; Dumat, Camille

2014-09-01

165

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

EPA Science Inventory

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

166

Size distribution measurement of fine and ultrafine particle emission from cooking Evelyne Ghina  

E-print Network

-suspension, sinks. dep dk is the deposition rate of the particles on the surfaces of the experimental chamber. coag and Balasubramaniana, 2006). We present here a comparison of particles emission rate (diameter in the range 5 nm to 1 at a maximum rate of 10 samples/second. The particle concentrations are measured every second for minimizing

Boyer, Edmond

167

A comparative study on the ultrafine particle episodes induced by vehicle exhaust: A crude oil refinery and ship emissions  

NASA Astrophysics Data System (ADS)

A study on the contribution of vehicle exhausts, ships and an oil refinery emission to the ambient air concentration of ultrafine particles (UFPs) is presented. It is based on a data set of particle number coarser than 2.5 nm (N), black carbon (BC), gaseous pollutants (NOx, SO2, CO and O3), PM2.5 and PM10 measured from 2008 to 2010 in the ambient air of Santa Cruz de Tenerife City, where a previous study found an association between hospitalizations due to heart failure and exposure to UFPs in the ambient air. The observed relationship between N, BC and gaseous pollutants allowed segregating UFP concentrations in a set of components linked to each source. It was found that vehicle exhausts contribute to the background of UFPs, whereas high UFP episodes were due to the emissions of the refinery and ships. The concentration of UFP linked to vehicle exhaust emissions maximized in the morning (07:00-09:00 GMT, 5000-25,000 cm- 3 = 25th-75th percentile), whereas those linked to ship (15,000-45,000 cm- 3) and refinery (25,000-95,000 cm- 3) emissions maximized in the 10:00-17:00 GMT period due to the effects of meteorology and photochemistry. It was found that the UFP concentrations were more sensitive to the fresh emissions of the three sources than PM2.5, which was mostly linked to aged fine particles (0.1-1 ?m) of the urban background. BC was the better tracer of vehicle exhaust emissions. It was concluded that the simultaneous monitoring of UFP, BC and PM2.5 is a suitable strategy of tracing aerosol pollutants of different nature (fresh vs. aged) and from different sources.

González, Yenny; Rodríguez, Sergio

2013-02-01

168

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

PubMed Central

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

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

2010-01-01

169

Complex nanominerals and ultrafine particles assemblages in phosphogypsum of the fertilizer industry and implications on human exposure.  

PubMed

Phosphogypsum (CaSO(4).2H(2)O), a by-product of phosphate-rock processing, contains high amounts of impurities such P(2)O(5), F, radioactive elements, organic substances, secondary nanominerals, and ultrafine particles (UFP) enriched in metals and metalloids. In this study, we examine phosphogypsum (PG) collected from abandoned fertilizer industry facility in south Brazil (Santa Catarina state). The fragile nature of nanominerals and UFP assemblages from fertilizer industry systems required novel techniques and experimental approaches. The investigation of the geochemistry of complex nanominerals and UFP assemblages was a prerequisite to accurately assess the environmental and human health risks of contaminants and cost-effective chemical and biogeological remediation strategies. Particular emphasis was placed on the study and characterization of the complex mixed nanominerals and UFP containing potentially toxic elements. Nanometer-sized phases in PG were characterized using energy-dispersive X-ray spectrometer (EDS), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM) images. The chemical composition and possible correlations with morphology of nanominerals and UFP, as well as aspects of nanominerals and UFP, are discussed in the context of human health exposure, as well as in relation to management of the nanominerals and UFP in PG environments. PMID:20701953

Silva, Luis F O; Hower, James C; Izquierdo, Maria; Querol, Xavier

2010-10-01

170

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

PubMed

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

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

2011-11-01

171

Evaluation of Multi-Year Continuous Measurements of Ultrafine Particles at Two Near-Road Stations in Toronto, Canada  

NASA Astrophysics Data System (ADS)

Particles with an aerodynamic diameter less than 100 nanometre (nm) are referred to as ultrafine particles (UFPs). Relative to fine and course particles, UFPs have greater potential to be suspended in air for a longer time and absorb toxic chemicals due to their larger surface areas per unit mass. UFPs could penetrate deep into the respiratory or cardiovascular systems and pose adverse health effects. In urban environments, primary sources of UFPs are from road traffic emissions and account for most of the total particle numbers. Controls on UPFs rely on better understanding of their emission sources and environmental behaviour. Ontario Ministry of the Environment have monitored UFPs since 2010 at two near-road stations in Toronto by using TSI 3031 UFP monitors. The two monitoring stations are approximately 20-30 meters adjacent to major arterial roads with over 20,000 vehicles per day. UFPs concentrations were monitored using six size channels: 20-30nm, 30-50nm, 50-70nm, 70-100nm, 100-200nm, and 200-450nm. Data are collected at time intervals of 11 or 15 minutes and averaged hourly. Concurrent measurements include wind speeds, wind directions, and concentrations of other air pollutants such as nitrogen oxides and black carbon. Data influenced by road-side traffic emissions were filtered by wind direction within 45° of normal to the road and wind speed greater than 1 m/s. Number concentrations were found higher for particles with sizes of 20-30nm and 30-50nm than for other sizes of UFPs. The observed particle number distributions are generally consistent with the theoretical understanding of particle nuclei mode and accumulation mode. During the day, for UFPs with sizes of 20-30nm and 30-50nm, elevated number concentrations were observed in morning traffic hours and to a less extent in the late afternoon. The elevated UFPs number concentrations coincided with nitrogen oxides and black carbon. Moreover, higher number concentrations were found on weekdays than weekends. The observations suggest that UFPs are mostly from traffic emissions. This presentation will provide an overview of the 3-year continuous near-road UPFs monitoring in Toronto and discuss how different factors influence number concentrations and environmental behaviour of UFPs.

Su, Y.; Sofowote, U.; Debosz, J.; Munoz, T.; Whitelaw, C.

2013-12-01

172

Ultrafine cementitious grout  

DOEpatents

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

Ahrens, Ernst H. (Albuquerque, NM)

1999-01-01

173

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

174

Ultrafine cementitious grout  

SciTech Connect

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

Ahrens, E.H.

1999-10-19

175

Application of a high-efficiency cabin air filter for simultaneous mitigation of ultrafine particle and carbon dioxide exposures inside passenger vehicles.  

PubMed

Modern passenger vehicles are commonly equipped with cabin air filters but their filtration efficiency for ultrafine particle (UFP) is rather low. Although setting the vehicle ventilation system to recirculation (RC) mode can reduce in-cabin UFPs by ? 90%, passenger-exhaled carbon dioxide (CO2) can quickly accumulate inside the cabin. Using outdoor air (OA) mode instead can provide sufficient air exchange to prevent CO2 buildup, but in-cabin UFP concentrations would increase. To overcome this dilemma, we developed a simultaneous mitigation method for UFP and CO2 using high-efficiency cabin air (HECA) filtration in OA mode. Concentrations of UFP and other air pollutants were simultaneously monitored in and out of 12 different vehicles under 3 driving conditions: stationary, on local roadways, and on freeways. Under each experimental condition, data were collected with no filter, in-use original equipment manufacturer (OEM) filter, and two types of HECA filters. The HECA filters offered an average in-cabin UFP reduction of 93%, much higher than the OEM filters (? 50% on average). Throughout the measurements, the in-cabin CO2 concentration remained in the range of 620-930 ppm, significantly lower than the typical level of 2500-4000 ppm observed in the RC mode. PMID:24471775

Lee, Eon S; Zhu, Yifang

2014-02-18

176

Translocation and potential neurological effects of fine and ultrafine particles a critical update  

Microsoft Academic Search

Particulate air pollution has been associated with respiratory and cardiovascular disease. Evidence for cardiovascular and neurodegenerative effects of ambient particles was reviewed as part of a workshop. The purpose of this critical update is to summarize the evidence presented for the mechanisms involved in the translocation of particles from the lung to other organs and to highlight the potential of

Annette Peters; Bellina Veronesi; Lilian Calderón-Garcidueñas; Peter Gehr; Lung Chi Chen; Marianne Geiser; William Reed; Barbara Rothen-Rutishauser; Samuel Schürch; Holger Schulz

2006-01-01

177

Computer simulations of interactions between ultrafine alumina particles produced by an arc discharge  

E-print Network

discharge M. H. Teng, L. D. Marks, and D. L. Johnson Department of Materials Science and Engineering sintering models assume spherical particle shape, and isotropic surface energy and diffusion coefficient.1 alumina particles were produced by an arc-discharge method, sintered in flight through a furnace

Marks, Laurence D.

178

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

179

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

2013-10-01

180

Capture efficiency of cooking-related fine and ultrafine particles by residential exhaust hoods.  

PubMed

Effective exhaust hoods can mitigate the indoor air quality impacts of pollutant emissions from residential cooking. This study reports capture efficiencies (CE) measured for cooking-generated particles for scripted cooking procedures in a 121-m(3) chamber with kitchenette. CEs also were measured for burner produced CO2 during cooking and separately for pots and pans containing water. The study used four exhaust hoods previously tested by Delp and Singer (Environ. Sci. Technol., 2012, 46, 6167-6173). For pan-frying a hamburger over medium heat on the back burner, CEs for particles were similar to those for burner produced CO2 and mostly above 80%. For stir-frying green beans in a wok (high heat, front burner), CEs for burner CO2 during cooking varied by hood and airflow: CEs were 34-38% for low (51-68 l/s) and 54-72% for high (109-138 l/s) settings. CEs for 0.3-2.0 ?m particles during front burner stir-frying were 3-11% on low and 16-70% on high settings. Results indicate that CEs measured for burner CO2 are not predictive of CEs of cooking-generated particles under all conditions, but they may be suitable to identify devices with CEs above 80% both for burner combustion products and for cooking-related particles. PMID:24750219

Lunden, M M; Delp, W W; Singer, B C

2015-02-01

181

Capture Efficiency of Cooking-Related Fine and Ultrafine Particles by Residential Exhaust Hoods  

SciTech Connect

Effective exhaust hoods can mitigate the indoor air quality impacts of pollutant emissions from residential cooking. This study reports capture efficiencies (CE) measured for cooking generated particles for scripted cooking procedures in a 121-m3 chamber with kitchenette. CEs also were measured for burner produced CO2 during cooking and separately for pots and pans containing water. The study used four exhaust hoods previously tested by Delp and Singer (Environ. Sci. Technol., 2012, 46, 6167-6173). For pan-frying a hamburger over medium heat on the back burner, CEs for particles were similar to those for burner produced CO2 and mostly above 80percent. For stir-frying green beans in a wok (high heat, front burner), CEs for burner CO2 during cooking varied by hood and airflow: CEs were 34-38percent for low (51?68 L s-1) and 54?72percent for high (109?138 L s-1) settings. CEs for 0.3?2.0 ?m particles during front burner stir-frying were 3?11percent on low and 16?70percent on high settings. Results indicate that CEs measured for burner CO2 are not predictive of CEs of cooking-generated particles under all conditions, but they may be suitable to identify devices with CEs above 80percent both for burner combustion products and for cooking-related particles.

Lunden, Melissa M.; Delp, William W.

2014-06-05

182

Using mobile monitoring to characterize roadway and aircraft contributions to ultrafine particle concentrations near a mid-sized airport  

NASA Astrophysics Data System (ADS)

Ultrafine particles (UFP) have complex spatial and temporal patterns that can be difficult to characterize, especially in areas with multiple source types. In this study, we utilized mobile monitoring and statistical modeling techniques to determine the contributions of both roadways and aircraft to spatial and temporal patterns of UFP in the communities surrounding an airport. A mobile monitoring campaign was conducted in five residential areas surrounding T.F. Green International Airport (Warwick, RI, USA) for one week in both spring and summer of 2008. Monitoring equipment and geographical positioning system (GPS) instruments were carried following scripted walking routes created to provide broad spatial coverage while recognizing the complexities of simultaneous spatial and temporal heterogeneity. Autoregressive integrated moving average models (ARIMA) were used to predict UFP concentrations as a function of distance from roadway, landing and take-off (LTO) activity, and meteorology. We found that distance to the nearest Class 2 roadway (highways and connector roads) was inversely associated with UFP concentrations in all neighborhoods. Departures and arrivals on a major runway had a significant influence on UFP concentrations in a neighborhood proximate to the end of the runway, with a limited influence elsewhere. Spatial patterns of regression model residuals indicate that spatial heterogeneity was partially explained by traffic and LTO terms, but with evidence that other factors may be contributing to elevated UFP close to the airport grounds. Regression model estimates indicate that mean traffic contributions exceed mean LTO contributions, but LTO activity can dominate the contribution during some minutes. Our combination of monitoring and statistical modeling techniques demonstrated contributions from major surrounding runways and LTO activity to UFP concentrations near a mid-sized airport, providing a methodology for source attribution within a community with multiple distinct sources.

Hsu, Hsiao-Hsien; Adamkiewicz, Gary; Houseman, E. Andres; Spengler, John D.; Levy, Jonathan I.

2014-06-01

183

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. PMID:23645993

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

2012-01-01

184

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

PubMed

Ultrafine particles (UFP; aerodynamic diameter < 0.1 micrometers) are a ubiquitous exposure in the urban environment and are elevated near highways. Most epidemiological studies of UFP health effects use central site monitoring data, which may misclassify exposure. Our aims were to: (1) examine the relationship between distant and proximate monitoring sites and their ability to predict hourly UFP concentration measured at residences in an urban community with a major interstate highway and; (2) determine if meteorology and proximity to traffic improve explanatory power. Short-term (1 - 3 weeks) residential monitoring of UFP concentration was conducted at 18 homes. Long-term monitoring was conducted at two near-highway monitoring sites and a central site. We created models of outdoor residential UFP concentration based on concentrations at the near-highway site, at the central site, at both sites together and without fixed sites. UFP concentration at residential sites was more highly correlated with those at a near-highway site than a central site. In regression models of each site alone, a 10% increase in UFP concentration at a near-highway site was associated with a 6% (95% CI: 6%, 7%) increase at residences while a 10% increase in UFP concentration at the central site was associated with a 3% (95% CI: 2%, 3%) increase at residences. A model including both sites showed minimal change in the magnitude of the association between the near-highway site and the residences, but the estimated association with UFP concentration at the central site was substantially attenuated. These associations remained after adjustment for other significant predictors of residential UFP concentration, including distance from highway, wind speed, wind direction, highway traffic volume and precipitation. The use of a central site as an estimate of personal exposure for populations near local emissions of traffic-related air pollutants may result in exposure misclassification. PMID:23645993

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

2012-09-01

185

Formation of ultrafine deferasirox particles via rapid expansion of supercritical solution (RESS process) using Taguchi approach.  

PubMed

The poor water solubility of many drugs is a challenge in pharmaceutical research. Recently, there have been great interests in finding environmentally friendly methods producing fine particles of pharmaceutical products for applications in pharmaceutical engineering. A promising method to improve the bioavailability of pharmaceutical agents is the rapid expansion of supercritical solutions. Deferasirox (DFS), a tridentate chelator, requires two molecules for iron (III) coordination. The bioavailability (the percentage of the drug absorbed compared to its initial dosage) is limited by this insolubility. The effect of four different RESS parameters including, extraction temperature (308-318K), extraction pressure (140-200 bar), effective nozzle diameter (500-1200 ?m), with and without cosolvents were investigated on the size and morphology of the precipitated particles of deferasirox based on Taguchi design. The results show great reduction in the size of the precipitated particles of deferasirox (50 nm-5 ?m) via RESS process compared with the original particles of deferasirox (5-500 ?m). PMID:22583849

Asghari, Iman; Esmaeilzadeh, Feridun

2012-08-20

186

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

187

Effects of Particle Filters and Accelerated Engine Replacement on Heavy-Duty Diesel Vehicle Emissions of Black Carbon, Nitrogen Oxides, and Ultrafine Particles  

NASA Astrophysics Data System (ADS)

Diesel particle filters have become widely used in the United States since the introduction in 2007 of a more stringent exhaust particulate matter emission standard for new heavy-duty diesel vehicle engines. California has instituted additional regulations requiring retrofit or replacement of older in-use engines to accelerate emission reductions and air quality improvements. This presentation summarizes pollutant emission changes measured over several field campaigns at the Port of Oakland in the San Francisco Bay Area associated with diesel particulate filter use and accelerated modernization of the heavy-duty truck fleet. Pollutants in the exhaust plumes of hundreds of heavy-duty trucks en route to the Port were measured in 2009, 2010, 2011, and 2013. Ultrafine particle number, black carbon (BC), nitrogen oxides (NOx), and nitrogen dioxide (NO2) concentrations were measured at a frequency ? 1 Hz and normalized to measured carbon dioxide concentrations to quantify fuel-based emission factors (grams of pollutant emitted per kilogram of diesel consumed). The size distribution of particles in truck exhaust plumes was also measured at 1 Hz. In the two most recent campaigns, emissions were linked on a truck-by-truck basis to installed emission control equipment via the matching of transcribed license plates to a Port truck database. Accelerated replacement of older engines with newer engines and retrofit of trucks with diesel particle filters reduced fleet-average emissions of BC and NOx. Preliminary results from the two most recent field campaigns indicate that trucks without diesel particle filters emit 4 times more BC than filter-equipped trucks. Diesel particle filters increase emissions of NO2, however, and filter-equipped trucks have NO2/NOx ratios that are 4 to 7 times greater than trucks without filters. Preliminary findings related to particle size distribution indicate that (a) most trucks emitted particles characterized by a single mode of approximately 100 nm in diameter and (b) new trucks originally equipped with diesel particle filters were 5 to 6 times more likely than filter-retrofitted trucks and trucks without filters to emit particles characterized by a single mode in the range of 10 to 30 nm in diameter.

Kirchstetter, T.; Preble, C.; Dallmann, T. R.; DeMartini, S. J.; Tang, N. W.; Kreisberg, N. M.; Hering, S. V.; Harley, R. A.

2013-12-01

188

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

189

Ultrafine aerosol diffusion charging: an improved interaction potential for metallic particles  

E-print Network

appreciation to my committee chairman Dr. W. H. Marlow for his guidance and encouragement for the entire duration of the work. He stimulated my interest in aerosol research via, the radon charging problem. He also provided the materials and support needed...' correction 39 11 Collision rate vs. diameter of particle, using Marlow's correction CHAPTER I INTRODUCTION I. l Introduction In recent years, the radiological dose to humans from airborne radioactivity associ- ated with naturally occurring radon has...

Zhu, Xiaowei, d 1963-

1989-01-01

190

Kerosene space heaters: A major source of ultrafine particles indoors Olivier Ramalho1,*  

E-print Network

.8±0.3)�1011 particle·s-1 . Chromium and manganese (4 and 0.05 ng·g-1 of burned fuel) were specifically associated, measurements with an optical counter (0.1 ­ 2 µm range in diameter) indicated a low but significant emission experimental chamber is a 2.36 m3 volume with glass, stainless steel or plexiglas walls (Figure 1). Gloves

Paris-Sud XI, Université de

191

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

192

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. PMID:20046215

Nico, Peter S.; Kumfer, Benjamin M.; Kennedy, Ian M.; Anastasio, Cort

2008-01-01

193

Particle Deposition in a Child Respiratory Tract Model: In Vivo Regional Deposition of Fine and Ultrafine Aerosols in Baboons  

E-print Network

and Ultrafine Aerosols in Baboons Iolanda Albuquerque-Silvaa,b,c , Laurent Vecelliod,e , Marc Duranda,c,f , John three baboons as a child respiratory tract model to assess regional deposition patterns (thoracic region% in the extrathoracic region and 51% ± 8% in the thoracic region. Finally, comparison of baboon and human inhalation

Boyer, Edmond

194

Source apportionment of size segregated fine/ultrafine particle by PMF in Beijing  

NASA Astrophysics Data System (ADS)

Considering the adverse health effects to human body, the number concentration of atmospheric PM (particulate material) is more important than the mass concentration. CO, NO, NO2, SO2 and number concentrations of PM were obtained from a remote site (Miyun), a roadside site (North Fourth Ring Road) and an urban residential site (Tsinghua University) in Beijing in winter. The size distribution and the possible sources of number concentrations were examined using EPA PMF (positive matrix factorization) model. A data set of totally 9610 of number concentration with the size range of 0.028 ?m to 0.948 ?m was included in the PMF analysis. The highest total particle number, mass and area of fine particles concentrations were observed at the North Fourth Ring Road site and the lowest were observed at Miyun site. Four factors were identified at Miyun site, as Factor 1 and Factor 4 may be related to long distance transportation, and Factor 2 and Factor 3 may be assigned as coal combustion and locomotive emission nearby, respectively; three factors were identified at North Fourth Ring Road, of which Factor 1 and Factor 3 are traffic related and Factor 2 may be coal combustion related. Compared with Factor 1, the contributions of Factor 3 to NOx and SO2 were 4-5 times higher. Additionally, Factor 3 was also a major contributor to CO. It suggested that Factor 1 and Factor 3 had the same source emission of motor vehicle, but different engine types, fuel types or exhaust treatments. Three factors were identified at Tsinghua site, as Factor 1 may come from aging vehicle emission, and Factor 2 and Factor 3 may be coal combustion related.

Tan, Ji-hua; Duan, Jing-chun; Chai, Fa-he; He, Ke-bin; Hao, Ji-Ming

2014-03-01

195

ULTRAFINE PARTICLE CELL INTERACTIONS IN VITRO: MOLECULAR MECHANISMS LEADING TO ALTERED GENE EXPRESSION IN RELATION TO PARTICLE COMPOSITION  

EPA Science Inventory

The results of these in vitro studies will identify specific mechanisms that are triggered following particle cell contact in a cell specific context and identify markers of cellular response. We predict that many of the subsequent physiologic effects in vivo are...

196

Endocytosis, oxidative stress and IL-8 expression in human lung epithelial cells upon treatment with fine and ultrafine TiO{sub 2}: Role of the specific surface area and of surface methylation of the particles  

SciTech Connect

Inhaled ultrafine particles show considerably stronger pulmonary inflammatory effects when tested at equal mass dose with their fine counterparts. However, the responsible mechanisms are not yet fully understood. We investigated the role of particle size and surface chemistry in initiating pro-inflammatory effects in vitro in A549 human lung epithelial cells on treatment with different model TiO{sub 2} particles. Two samples of TiO{sub 2}, i.e. fine (40-300 nm) and ultrafine (20-80 nm) were tested in their native forms as well as upon surface methylation, as was confirmed by Fourier transformed infrared spectroscopy. Radical generation during cell treatment was determined by electron paramagnetic resonance with 5,5-dimethyl-1-pyrroline-N-oxide or 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. Interleukin-8 mRNA expression/release was determined by RT-PCR and ELISA, whereas particle uptake was evaluated by transmission electron microscopy. TiO{sub 2} particles were rapidly taken up by the cells, generally as membrane bound aggregates and large intracellular aggregates in vesicles, vacuoles and lamellar bodies. Aggregate size tended to be smaller for the ultrafine samples and was also smaller for methylated fine TiO{sub 2} when compared to non-methylated fine TiO{sub 2}. No particles were observed inside nuclei or any other vital organelle. Both ultrafine TiO{sub 2} samples but not their fine counterparts elicited significantly stronger oxidant generation and IL-8 release, despite their aggregation state and irrespective of their methylation. The present data indicate that ultrafine TiO{sub 2}, even as aggregates/agglomerates, can trigger inflammatory responses that appear to be driven by their large surface area. Furthermore, our results indicate that these effects result from oxidants generated during particle-cell interactions through a yet to be elucidated mechanism(s)

Singh, Seema [Institut fuer umweltmedizinische Forschung (IUF) an der Heinrich-Heine Universitaet Duesseldorf gGmbH (Germany)]|[Energy and Resources Institute (TERI), New Delhi (India); Shi, Tingming [Institut fuer umweltmedizinische Forschung (IUF) an der Heinrich-Heine Universitaet Duesseldorf gGmbH (Germany)]|[Hubei Provincial Centre for Disease Control and Prevention, Wuhan, Hubei (China); Duffin, Rodger [Institut fuer umweltmedizinische Forschung (IUF) an der Heinrich-Heine Universitaet Duesseldorf gGmbH (Germany)]|[Centre for Inflammation Research (CIR), The Queen's Medical Research Institute, University of Edinburgh (United Kingdom); Albrecht, Catrin; Berlo, Damien van; Hoehr, Doris [Institut fuer umweltmedizinische Forschung (IUF) an der Heinrich-Heine Universitaet Duesseldorf gGmbH (Germany); Fubini, Bice; Martra, Gianmario; Fenoglio, Ivana [Dipartimento di Chimica IFM, Interdepartmental Center 'G. Scansetti' for Studies on Asbestos and other Toxic Particulates and NIS Centre of Excellence of Nanostructured Interfaces and Surfaces, Universita degli Studi di Torino (Italy); Borm, Paul J.A. [Institut fuer umweltmedizinische Forschung (IUF) an der Heinrich-Heine Universitaet Duesseldorf gGmbH (Germany)]|[Hogeschool Zuyd, Heerlen (Netherlands); Schins, Roel P.F. [Institut fuer umweltmedizinische Forschung (IUF) an der Heinrich-Heine Universitaet Duesseldorf gGmbH (Germany)]. E-mail: roel.schins@uni-duesseldorf.de

2007-07-15

197

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

198

Ultrafine particle levels at an international port of entry between the US and Mexico: exposure implications for users, workers, and neighbors.  

PubMed

Exposure to diesel-emitted particles has been linked to increased cancer risk and cardiopulmonary diseases. Because of their size (<100 nm), exposure to ultrafine particles (UFPs) emitted from heavy-duty diesel vehicles (HDDV) might result in greater health risks than those associated with larger particles. Seasonal UFP levels at the International Bridge of the Americas, which connects the US and Mexico and has high HDDV traffic demands, were characterized. Hourly average UFP concentrations ranged between 1.7 × 10(3)/cc and 2.9 × 10(5)/cc with a mean of 3.5 × 10(4)/cc. Wind speeds <2 m?s(-1) and temperatures <15?°C were associated with particle number concentrations above normal conditions. The presence of HDDV had the strongest impact on local UFP levels. Varying particle size distributions were associated with south- and northbound HDDV traffic. Peak exposure occurred on weekday afternoons. Although in winter, high exposure episodes were also observed in the morning. Particle number concentrations were estimated to reach background levels at 400 m away from traffic. The populations exposed to UFP above background levels include law enforcement officers, street vendors, private commuters, and commercial vehicle drivers as well as neighbors on both sides of the border, including a church and several schools. PMID:23321858

Olvera, Hector A; Lopez, Mario; Guerrero, Veronica; Garcia, Humberto; Li, Wen-Whai

2013-01-01

199

Frequency-dependent AMS of rocks: A tool for the investigation of the fabric of ultrafine magnetic particles  

NASA Astrophysics Data System (ADS)

In some geological processes, new very fine-grained magnetic minerals may originate. The variation in content of these minerals is routinely investigated by frequency-dependent magnetic susceptibility, which is traditionally interpreted in terms of the presence of viscous superparamagnetic (SP) particles in addition to stable single domain (SSD) and multidomain (MD) magnetic particles. In addition, the fabric of these grains can be investigated through the frequency-dependent AMS. Through standard AMS measurement at different frequencies, one can evaluate the contribution of SP particles to the whole-rock AMS; appropriate methods were developed. Various rocks, soils and ceramics, showing frequency-dependent magnetic susceptibility, were investigated. Measurable changes of AMS with operating frequency were revealed and attempts are made of their fabric interpretation.

Hrouda, František; Ježek, Josef

2014-08-01

200

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

201

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

202

Hygroscopic properties of newly formed ultrafine particles at an urban site surrounded by deciduous forest (Sapporo, northern Japan) during the summer of 2011  

NASA Astrophysics Data System (ADS)

To investigate the hygroscopic properties of ultrafine particles during new particle formation events, the hygroscopic growth factors of size-segregated atmospheric particles were measured at an urban site in Sapporo, northern Japan, during the summer of 2011. The hygroscopic growth factor at 85 % relative humidity [g(85%)] of freshly formed nucleation mode particles was 1.11 to 1.28 (average: 1.16 ± 0.06) at a dry particle diameter (Dp) centered on 20 nm, which is equivalent to 1.17 to 1.35 (1.23 ± 0.06) at a dry Dp centered on 100 nm after considering the Kelvin effect. These values are comparable with those of secondary organic aerosols, suggesting that low-volatility organic vapors are important to the burst of nucleation mode particles. The equivalent g(85%) at a dry Dp of 100 nm for nucleated particles that have grown to Aitken mode sizes (1.24 to 1.34; average: 1.30 ± 0.04) were slightly higher than those of newly formed nucleation mode particles, suggesting that the growth of freshly formed nucleation mode particles to the Aitken mode size can be subjected to condensation of not only low-volatility organic vapors, but also water-soluble inorganic species. Based on this result, and previous measurement of radiocarbon in aerosols, we suggest that the burst of nucleation mode particles and their subsequent growth were highly affected by biogenic organic emissions at this measurement site, which is surrounded by deciduous forest. Gradual increases in mode diameter after the burst of nucleation mode particles were observed under southerly wind conditions, with a dominant contribution of intermediately hygroscopic particles. However, sharp increases in mode diameter were observed when the wind direction shifted to northwesterly or northeasterly, with a sharp increase in the highly hygroscopic particle fraction of the Aitken mode particles, indicating that the hygroscopic growth factor of newly formed particles is perturbed by the local winds that deliver different air masses to the measurement site.

Jung, J.; Kawamura, K.

2014-07-01

203

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

204

Consequences of developmental exposure to concentrated ambient ultrafine particle air pollution combined with the adult paraquat and maneb model of the Parkinson's disease phenotype in male mice.  

PubMed

Current evidence suggests suceptibility of both the substantia nigra and striatum to exposure to components of air pollution. Further, air pollution has been associated with increased risk of PD diagnsosis in humans or PD-like pathology in animals. This study examined whether exposure of mice to concentrated ambient ultrafine particles (CAPS; <100nm diameter) during the first two weeks of life would alter susceptibility to induction of the Parkinson's disease phenyotype (PDP) in a pesticide-based paraquat and maneb (PQ+MB) model during adulthood utilizing i.p. injections of 10mg/kg PQ and 30mg/kg MB 2× per week for 6 weeks. Evidence of CAPS-induced enhancement of the PQ+MB PDP was limited primarily to delayed recovery of locomotor activity 24 post-injection of PQ+MB that could be related to alterations in striatal GABA inhibitory function. Absence of more extensive interactions might also reflect the finding that CAPS and PQ+MB appeared to differentially target the nigrostriatal dopamine and amino acid systems, with CAPS impacting striatum and PQ+MB impacting dopamine-glutamate function in midbrain; both CAPS and PQ+MB elevated glutamate levels in these specific regions, consistent with potential excitotoxicity. These findings demonstrate the ability of postnatal CAPS to produce locomotor dysfunction and dopaminergic and glutamateric changes, independent of PQ+MB, in brain regions involved in the PDP. PMID:24486957

Allen, Joshua L; Liu, Xiufang; Weston, Douglas; Conrad, Katherine; Oberdörster, Günter; Cory-Slechta, Deborah A

2014-03-01

205

Effect of Exposure to Atmospheric Ultrafine Particles on Production of Free Fatty Acids and Lipid Metabolites in the Mouse Small Intestine  

PubMed Central

Background: Exposure to ambient ultrafine particulate matter (UFP) is a well-recognized risk factor for cardiovascular and respiratory diseases. However, little is known about the effects of air pollution on gastrointestinal disorders. Objective: We sought to assess whether exposure to ambient UFP (diameter < 180 nm) increased free fatty acids and lipid metabolites in the mouse small intestine. Methods: Ldlr-null mice were exposed to filtered air (FA) or UFP collected at an urban Los Angeles, California, site that was heavily affected by vehicular emissions; the exposure was carried out for 10 weeks in the presence or absence of D-4F, an apolipoprotein A-I mimetic peptide with antioxidant and anti-inflammation properties on a high-fat or normal chow diet. Results: Compared with FA, exposure to UFP significantly increased intestinal hydroxyeicosatetraenoic acids (HETEs), including 15-HETE, 12-HETE, 5-HETE, as well as hydroxyoctadecadienoic acids (HODEs), including 13-HODE and 9-HODE. Arachidonic acid (AA) and prostaglandin D2 (PGD2) as well as some of the lysophosphatidic acids (LPA) in the small intestine were also increased in response to UFP exposure. Administration of D-4F significantly reduced UFP-mediated increase in HETEs, HODEs, AA, PGD2, and LPA. Although exposure to UFP further led to shortened villus length accompanied by prominent macrophage and neutrophil infiltration into the intestinal villi, administration of D-4F mitigated macrophage infiltration. Conclusions: Exposure to UFP promotes lipid metabolism, villus shortening, and inflammatory responses in mouse small intestine, whereas administration of D-4F attenuated these effects. Our findings provide a basis to further assess the mechanisms underlying UFP-mediated lipid metabolism in the digestive system with clinical relevance to gut homeostasis and diseases. Citation: Li R, Navab K, Hough G, Daher N, Zhang M, Mittelstein D, Lee K, Pakbin P, Saffari A, Bhetraratana M, Sulaiman D, Beebe T, Wu L, Jen N, Wine E, Tseng CH, Araujo JA, Fogelman A, Sioutas C, Navab M, Hsiai TK. 2015. Effect of exposure to atmospheric ultrafine particles on production of free fatty acids and lipid metabolites in the mouse small intestine. Environ Health Perspect 123:34–41;?http://dx.doi.org/10.1289/ehp.1307036 PMID:25170928

Li, Rongsong; Navab, Kaveh; Hough, Greg; Daher, Nancy; Zhang, Min; Mittelstein, David; Lee, Katherine; Pakbin, Payam; Saffari, Arian; Bhetraratana, May; Sulaiman, Dawoud; Beebe, Tyler; Wu, Lan; Jen, Nelson; Wine, Eytan; Tseng, Chi-Hong; Araujo, Jesus A.; Fogelman, Alan; Sioutas, Constantinos; Navab, Mohamed

2014-01-01

206

FINE PARTICLE CHARGING DEVELOPMENT  

EPA Science Inventory

The report gives results of theoretical and experimental investigations into the changing of fine particles by unipolar ions in an electric field, and evaluation of a specially designed small pilot-scale (600-1000 acfm) precharging device. Following an extensive review of the lit...

207

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

208

Investigations of percutaneous uptake of ultrafine TiO 2 particles at the high energy ion nanoprobe LIPSION  

NASA Astrophysics Data System (ADS)

Micronised TiO 2 particles with a diameter of about 15 nm are used in sunscreens as physical UV filter. Due to the small particle size it may be supposed that TiO 2 particles can pass through the uppermost horny skin layer ( stratum corneum) via intercellular channels and penetrate into deeper vital skin layers. Accumulations of TiO 2 particles in the skin can decrease the threshold for allergies of the immune system or cause allergic reactions directly. Spatially resolved ion beam analysis (PIXE, RBS, STIM and secondary electron imaging) was carried out on freeze-dried cross-sections of biopsies of pig skin, on which four different formulations containing TiO 2 particles were applied. The investigations were carried out at the high energy ion nanoprobe LIPSION in Leipzig with a 2.25 MeV proton beam, which was focused to a diameter of 1 ?m. The analysis concentrated on the penetration depth and on pathways of the TiO 2 particles into the skin. In these measurements a penetration of TiO 2 particles through the s. corneum into the underlying stratum granulosum via intercellular space was found. Hair follicles do not seem to be important penetration pathways because no TiO 2 was detected inside. The TiO 2 particle concentration in the stratum spinosum was below the minimum detection limit of about 1 particle/?m 2. These findings show the importance of coating the TiO 2 particles in order to prevent damage of RNA and DNA of skin cells by photocatalytic reactions of the penetrated particles caused by absorption of UV light.

Menzel, F.; Reinert, T.; Vogt, J.; Butz, T.

2004-06-01

209

Indoor/outdoor relationships of quasi-ultrafine, accumulation and coarse mode particles in school environments in Barcelona: chemical composition and sources  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

210

Comprehensive Characterization Of Ultrafine Particulate Emission From 2007 Diesel Engines: PM Size Distribution, Loading And Indidividual Particle Size And Composition.  

NASA Astrophysics Data System (ADS)

The strong absorption of solar radiation by black carbon (BC) impacts the atmospheric radiative balance in a complex and significant manner. One of the most important sources of BC is vehicular emissions, of which diesel represents a significant fraction. To address this issue the EPA has issues new stringent regulations that will be in effect in 2007, limiting the amount of particulate mass that can be emitted by diesel engines. The new engines are equipped with aftertreatments that reduce PM emissions to the point, where filter measurements are subject to significant artifacts and characterization by other techniques presents new challenges. We will present the results of the multidisciplinary study conducted at the Cummins Technical Center in which a suite of instruments was deployed to yield comprehensive, temporally resolved information on the diesel exhaust particle loadings and properties in real-time: Particle size distributions were measured by Engine Exhaust Particle Sizer (EEPS) and Scanning Mobility Particle Sizer (SMPS). Total particle diameter concentration was obtained using Electrical Aerosol Detector (EAD). Laser Induced Incandescence and photoacoustic techniques were used to monitor the PM soot content. Single Particle Laser Ablation Time-of- flight Mass Spectrometer (SPLAT) provided the aerodynamic diameter and chemical composition of individual diesel exhaust particles. Measurements were conducted on a number of heavy duty diesel engines operated under variety of operating conditions, including FTP transient cycles, ramped-modal cycles and steady states runs. We have also characterized PM emissions during diesel particulate filter regeneration cycles. We will present a comparison of PM characteristics observed during identical cycles, but with and without the use of aftertreatment. A total of approximately 100,000 individual particles were sized and their composition characterized by SPLAT. The aerodynamic size distributions of the characterized particles were between 50 and 300 nm, depending on engine operating conditions and particle composition. We will show that while the drastically reduced diesel PM emissions often render the PM filter measurements inadequate due to organic vapor artifacts SPLAT demonstrated its capability to provide real-time information on size and composition of individual diesel exhaust particles as function of engine operating conditions with better than 1 minute resolution.

Zelenyuk, A.; Cuadra-Rodriguez, L. A.; Imre, D.; Shimpi, S.; Warey, A.

2006-12-01

211

Facile Fabrication of Ultrafine Copper Nanoparticles in Organic Solvent  

NASA Astrophysics Data System (ADS)

A facile chemical reduction method has been developed to fabricate ultrafine copper nanoparticles whose sizes can be controlled down to ca. 1 nm by using poly( N-vinylpyrrolidone) (PVP) as the stabilizer and sodium borohyrdride as the reducing agent in an alkaline ethylene glycol (EG) solvent. Transmission electron microscopy (TEM) results and UV-vis absorption spectra demonstrated that the as-prepared particles were well monodispersed, mostly composed of pure metallic Cu nanocrystals and extremely stable over extended period of simply sealed storage.

Zhang, Han-Xuan; Siegert, Uwe; Liu, Ran; Cai, Wen-Bin

2009-07-01

212

Sol–Gel and Ultrafine Particle Formation via Dielectric Tuning of Inorganic Salt–Alcohol–Water Solutions  

Microsoft Academic Search

Under some conditions, inorganic salts can be as good precursors for sol–gel-type processing as those obtained from expensive metalloorganic precursors such as alkoxides. In this work, the formation of monodispersed hydrous zirconia microsphere particles (particularly nanosized) and gels was achieved in solutions of zirconyl chloride dissolved in alcohol–water mixed solvents. The dielectric property of the mixed alcohol–water solvent directly affects

Michael Z.-C. Hu; E. Andrew Payzant; Charles H. Byers

2000-01-01

213

Preferred Crystallographic Orientation Development in Nano/Ultrafine-Grained 316L Stainless Steel During Martensite to Austenite Reversion  

NASA Astrophysics Data System (ADS)

The crystallographic orientation of cold-rolled 316L stainless steel is investigated during reversion of strain-induced ?-martensite to nano/ultrafine-grained austenite upon annealing at 750 °C for different holding times; 1, 5, 15, and 30 min. The texture of nanoscale reverted austenite reveals a Brass ({110}<112>) and a Goss ({110}<100>) textures after annealing for 1 min. No new texture component is appeared through the completion of martensite to austenite reversion for 5 min, but the intensity of Brass and Goss textures are increased. Further annealing for 30 min results in a stronger texture with higher intensity for Brass compared to Goss.

Eskandari, M.; Mohtadi-Bonab, M. A.; Basu, R.; Nezakat, M.; Kermanpur, A.; Szpunar, J. A.; Nahar, S.; Baghpanah, A. H.

2014-12-01

214

Development of porosity in an oxide dispersion strengthened ferritic alloy containing nanoscale oxide particles  

SciTech Connect

The development of porosity at 1000 C in an oxide dispersion strengthened ferritic alloy containing ultra-fine oxide particles with diameters on the order of a few nm is investigated. A comparison with an alloy fabricated by internal oxidation demonstrates that the porosity formation is associated with mechanical alloying with Y2O3 in argon. The pores grow in spite of a sub-micron grain size suggesting that the grain boundaries are not effective paths for removing entrapped gas from the pores.

Schneibel, Joachim H [ORNL; Liu, Chain T [ORNL; Hoelzer, David T [ORNL; Mills, Michael J. [Ohio State University; Sarosi, P. M. [Ohio State University; Hayashi, Taisuke [Ohio State University; Wendt, Ullrich [Otto-von-Guericke Universitat, Magdeburg, Germany; Heyse, Hartmut [Otto-von-Guericke Universitat, Magdeburg, Germany

2007-01-01

215

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

216

journal JAmCeramSoc,77[5]114352(1994) Thin Glass Film between Ultrafine Conductor Particles in  

E-print Network

Research and Development, DuPont Company, Wdmington, Delaware 19880 Rowland M. Cannon* Lawrence Berkeley-22933. YMC was supported by the DuPont Company Visiting Research Scientist program during part of this work in film thickness as well as to local chemical changesof two possible types. Titania enrichment within

Rollins, Andrew M.

217

Ultrafine particles from diesel vehicle emissions at different driving cycles induce differential vascular pro-inflammatory responses: Implication of chemical components and NF-?B signaling  

PubMed Central

Background Epidemiological evidence supports the association between exposure to ambient particulate matter (PM) and cardiovascular diseases. Chronic exposure to ultrafine particles (UFP; Dp <100 nm) is reported to promote atherosclerosis in ApoE knockout mice. Atherogenesis-prone factors induce endothelial dysfunction that contributes to the initiation and progression of atherosclerosis. We previously demonstrated that UFP induced oxidative stress via c-Jun N-terminal Kinases (JNK) activation in endothelial cells. In this study, we investigated pro-inflammatory responses of human aortic endothelial cells (HAEC) exposed to UFP emitted from a diesel truck under an idling mode (UFP1) and an urban dynamometer driving schedule (UFP2), respectively. We hypothesize that UFP1 and UFP2 with distinct chemical compositions induce differential pro-inflammatory responses in endothelial cells. Results UFP2 contained a higher level of redox active organic compounds and metals on a per PM mass basis than UFP1. While both UFP1 and UFP2 induced superoxide production and up-regulated stress response genes such as heme oxygenease-1 (HO-1), OKL38, and tissue factor (TF), only UFP2 induced the expression of pro-inflammatory genes such as IL-8 (2.8 ± 0.3-fold), MCP-1 (3.9 ± 0.4-fold), and VCAM (6.5 ± 1.1-fold) (n = 3, P < 0.05). UFP2-exposed HAEC also bound to a higher number of monocytes than UFP1-exposed HAEC (Control = 70 ± 7.5, UFP1 = 106.7 ± 12.5, UFP2 = 137.0 ± 8.0, n = 3, P < 0.05). Adenovirus NF-?B Luciferase reporter assays revealed that UFP2, but not UFP1, significantly induced NF-?B activities. NF-?B inhibitor, CAY10512, significantly abrogated UFP2-induced pro-inflammatory gene expression and monocyte binding. Conclusion While UFP1 induced higher level of oxidative stress and stress response gene expression, only UFP2, with higher levels of redox active organic compounds and metals, induced pro-inflammatory responses via NF-?B signaling. Thus, UFP with distinct chemical compositions caused differential response patterns in endothelial cells. PMID:20307321

2010-01-01

218

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

219

Development of ultrafine-grained microstructure in Al-Cu-Mg alloy through equal-channel angular pressing  

NASA Astrophysics Data System (ADS)

Al-Cu-Mg alloys are extensively used for riveting applications in aerospace industries due to their relatively high shear strength coupled with high plasticity. The significant advantage of using V65 aluminum alloy ((Al-4Cu-0.2Mg) for rivet application also stems from its significantly slower natural aging kinetics, which gives operational flexibility to carryout riveting operation even after 4 days of solution heat treatment, in contrast to its equivalent alloy AA2024.Rivets are usually made by cold heading of wire rods. In order to form a defect free rivet head, grain size control in wire rods is essential at each and every stage of processing right from casting onwards upto the final wire drawing stage. Wire drawing is carried out at room temperature to reduce diameter as well as impart good surface finish. In the present study, different microstructures in V65 alloy bars were produced by rolling at different temperatures (room temperature to 523K) and subsequently deformed by equal channel angular pressing (ECAP) at 423K upto an equivalent strain of 7. ECAP was carried out to study the effect of initial microstructure on grain refinement and degree of deformation on the evolution of ultrafine grain structure. The refinement of V65 alloy by ECAP is significantly influenced by Initial microstructure but amount of deformation strongly affects the evolution processes as revealed by optical microscopy and transmission electron microscopy.

Sai Anuhya, Danam; Gupta, Ashutosh; Nayan, Niraj; Narayana Murty, S. V. S.; Manna, R.; Sastry, G. V. S.

2014-08-01

220

Ultrafine PEG-coated poly(lactic-co-glycolic acid) nanoparticles formulated by hydrophobic surfactant-assisted one-pot synthesis for biomedical applications  

NASA Astrophysics Data System (ADS)

A novel method was developed for the one-pot synthesis of ultrafine poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs), using an emulsion solvent evaporation formulation method. Using either cetyltrimethylammonium bromide (CTAB) or poly(ethylene glycol)-distearyl phosphoethanolamine (PEGPE) as an oily emulsifier during the emulsion process, produced PLGA particle sizes of less than 50 nm, constituting a breakthrough in emulsion formulation methods. The yield of ultrafine PLGA NPs increased with PEGPE/PLGA ratio, reaching a plateau at around 85%, when the PEGPE/PLGA ratio reached 3:1. The PEGPE-PLGA NPs exhibited high drug loading content, reduced burst release, good serum stability, and enhanced cell uptake rate compared with traditional PLGA NPs. Sub-50 nm diameter PEG-coated ultrafine PLGA NPs show great potential for in vivo drug delivery systems.

Chu, Chih-Hang; Wang, Yu-Chao; Huang, Hsin-Ying; Wu, Li-Chen; Yang, Chung-Shi

2011-05-01

221

Ultrafine metal oxides dismantle chlorinated organics  

SciTech Connect

Researchers at Kansas State University (Manhattan) have developed a low-temperature, noncatalytic process that destroys chlorinated organic compounds without creating harmful byproducts. The process, dubbed destructive adsorption, uses ultrafine particles of several common metal oxides to convert chlorocarbon molecules into metal chlorides and carbon oxides. To date, the process has only been demonstrated for the bench-scale decomposition of carbon tetrachloride (CCl{sub 4}). However, Colorado-based NanTech has recently been awarded a grant to develop the process for commercialization. Certain metal oxides, such as CaO and MgO, react favorably with many of the chlorinated organics commonly found in industrial exhaust streams, and in the organics-laden vapors commonly recovered during soil and groundwater remediation. In the presence of chlorinated compounds such as carbon tetrachloride (CCl{sub 4}), chloroform (CHCl{sub 3}), tetrachloroethylene (C{sub 2}Cl{sub 4}) and chlorobenzene (C{sub 6}H{sub 5}Cl), these metal oxides adsorb chlorine atoms to form metal chlorides (MgCl{sub 2} or CaCl{sub 2}), and their oxygen atoms combine with carbon in the organics to form CO and CO{sub 2}. While these reactions are favorable from a thermodynamic standpoint (all are mildly exothermic), reaction rates are kinetically limited, because they involve solid-gas or solid-liquid reactions. As the metal chloride forms on the surface of the metal oxide, the resulting salt buildup gradually impedes--and eventually prevents--the reaction between the metal oxide and the chlorocarbon compound. To overcome this obstacle, the Kansas State researchers experimented with extremely small particles of metal oxides--less than 25 nanometers dia.--to maximize overall surface area. This increased the reactivity and the capacity of the metal oxide particles.

NONE

1995-07-01

222

Coated particle waste form development  

SciTech Connect

Coated particle waste forms have been developed as part of the multibarrier concept at Pacific Northwest Laboratory under the Alternative Waste Forms Program for the Department of Energy. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low-temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed (FB) coaters, screw agitated coaters (SAC), and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated at PNL as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders-of-magnitude increase in chemical durability. Because the aluminum coatings were porous, the superior leach resistance must be due to either a chemical interaction or to a pH buffer effect. Because they are complex, coated waste form processes rank low in process feasibility. Of all the possible coated particle processes, plasma sprayed marbles have the best rating. Carbon coating of pellets by CVD ranked ninth when compared with ten other processes. The plasma-spray-coated marble process ranked sixth out of eleven processes.

Oma, K.H.; Buckwalter, C.Q.; Chick, L.A.

1981-12-01

223

Coated particle waste form development  

NASA Astrophysics Data System (ADS)

Coated particle waste forms were developed as part of the multibarrier concept. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed coaters, screw agitated coaters, and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders of magnitude increase in chemical durability.

Oma, K. H.; Buckwalter, C. Q.; Chick, L. A.

1981-12-01

224

A new and superior ultrafine cementitious grout  

SciTech Connect

Sealing fractures in nuclear waste repositories concerns all programs investigating deep burial as a means of disposal. Because the most likely mechanism for contaminant migration is by dissolution and movement through groundwater, sealing programs are seeking low-viscosity sealants that are chemically, mineralogically, and physically compatible with the host rock. This paper presents the results of collaborative work directed by Sandia National Laboratories (SNL) and supported by Whiteshell Laboratories, operated by Atomic Energy of Canada, Ltd. The work was undertaken in support of the Waste Isolation Pilot Plant (WIPP), an underground nuclear waste repository located in a salt formation east of Carlsbad, NM. This effort addresses the technology associated with long-term isolation of nuclear waste in a natural salt medium. The work presented is part of the WIPP plugging and sealing program, specifically the development and optimization of an ultrafine cementitious grout that can be injected to lower excessive, strain-induced hydraulic conductivity in the fractured rock termed the Disturbed Rock Zone (DRZ) surrounding underground excavations. Innovative equipment and procedures employed in the laboratory produced a usable cement-based grout; 90% of the particles were smaller than 8 microns and the average particle size was 4 microns. The process involved simultaneous wet pulverization and mixing. The grout was used for a successful in situ test underground at the WIPP. Injection of grout sealed microfractures as small as 6 microns (and in one rare instance, 3 microns) and lowered the gas transmissivity of the DRZ by up to three orders of magnitude. Following the WIPP test, additional work produced an improved version of the grout containing particles 90% smaller than 5 microns and averaging 2 microns. This grout will be produced in dry form, ready for the mixer.

Ahrens, E.H.

1997-04-01

225

Effect of reductant and PVP on morphology and magnetic property of ultrafine Ni powders prepared via hydrothermal route  

SciTech Connect

Graphical abstract: The ultrafine Ni powders with the shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using different reductants. Their saturation magnetization, remanent magnetization and coercivity sequentially increase, and the coercivity of hexagonal sheet-like Ni powders increases by 25% compared with the Ni bulk counterpart. - Highlights: • The ultrafine Ni powders with various shapes of sphere, fish-bone, hexagonal sheet, etc. • Facile and one-step hydrothermal reduction using three reductants and PVP additive was developed. • Magnetic properties of the ultrafine Ni powders with different shapes were measured. • Compared with bulk Ni material, coercivity of hexagonal sheet Ni increases by 25%. • The formation mechanism of the shapes was suggested. - Abstract: The ultrafine nickel particles with different shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using hydrazine hydrate, sodium hypophosphite and ethylene glycol as reductants, polyvinylpyrrolidone as structure-directing agent. It has been verified with the characterization of X-ray powder diffraction and transmission/scanning electronic microscopy that as-prepared products belong to face-centered cubic structure of nickel microcrystals with high purity and fine dispersity. The magnetic hysteresis loops measured at room temperature reveal that the values of saturation magnetization, remanent magnetization and coercivity rise sequentially from silknet, sphere to hexagonal sheet. In comparison with nickel bulk counterpart, the coercivity of the hexagonal sheet nickel powders increases by 25%.

Zhang, Jun, E-mail: j-zhang@126.com; Wang, Xiucai; Li, Lili; Li, Chengxuan; Peng, Shuge

2013-10-15

226

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

227

Preparation of ultrafine boride powders by metallothermic reduction method  

NASA Astrophysics Data System (ADS)

Ultrafine TiB2, ZrB2, and ReB2 powders were prepared by the metallothermic reduction method using Mg. Obtained TiB2, ZrB2, and ReB2 powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and scratch test. The morphology of the powders was a laminar hexagonal single crystal. The mean particle sizes of TiB2 and ZrB2 increased with increasing reaction temperature, and that of ReB2 was 0.11 ?m at 1093 K. The obtained ReB2 powder can scratch the surface of polycrystalline synthetic diamonds (HK = 7000 kg/mm2). The obtained powders will be useful for developing of new superhard alloys and pigments.

Nishiyama, Katsuhiro; Nakamur, Takanobu; Utsumi, Shigenori; Sakai, Hideki; Abe, Masahiko

2009-06-01

228

Health hazards of ultrafine metal and metal oxide powders  

NASA Technical Reports Server (NTRS)

Study reveals that suggested threshold limit values are from two to fifty times lower than current recommended threshold limit values. Proposed safe limits of exposure to the ultrafine dusts are based on known toxic potential of various materials as determined in particle size ranges.

Boylen, G. W., Jr.; Chamberlin, R. I.; Viles, F. J.

1969-01-01

229

Microstructure development and densification of ultrafine Y-TZP monoliths obtained by seeding-assisted chemical coprecipitation  

Microsoft Academic Search

Y-TZP seeded gel monoliths have been prepared by a sol–gel method based on the coprecipitation of Zr4+ and Y3+ precursors as hydroxides and the stabilisation of the suspension in pure ethanol with a disc turbine. The addition of solid Y-TZP nanometer-size seed particles (10 wt%) into the Y-TZP precursor solution plays a crucial role during crystallisation and densification of monoliths.

J. Tartaj; E. Lachowski; J. F. Fernández; C. Moure; P. Durán

2000-01-01

230

Measurement and identification of ultrafine bubbles by resonant mass measurement method  

NASA Astrophysics Data System (ADS)

Various methods have been used to measure the particle size and number density of ultrafine bubbles generated by the ultrafine bubble generator, ultrafineGALF. The presence of particles with diameters of about 100 to 200 nm was indicated by every method that we used before. However, absolute identification of these as ultrafine bubbles rather than some other type of particle was not possible because conventional measurement methods using light generated by a laser and scattered by particles do not distinguish dust particles from bubbles. The present series of experiments, using the resonant mass measurement method, was the first to succeed in clearly distinguishing ultrafine bubbles from other particles. This was due to the use of the resonant mass measurement method, which is capable of distinguishing positively buoyant particles (bubbles) from negatively buoyant particles. In addition, the results from the resonant mass measurement method were compared, in terms of particle size distribution, with this from the particle tracking analysis method, which uses a different measurement principle. The particle size distributions yielded by both methods showed a moderate correlation between the number density results obtained by each.

Kobayashi, Hideaki; Maeda, Shigeo; Kashiwa, Masakazu; Fujita, Toshihiro

2014-08-01

231

Real-world PM, NO x, CO, and ultrafine particle emission factors for military non-road heavy duty diesel vehicles  

NASA Astrophysics Data System (ADS)

Training on US military bases involves nonroad diesel vehicles with emissions that can affect base personnel, nearby communities, and attainment of air quality standards. Nonroad diesel engines contribute 44% of diesel PM and 12% of total NO x emissions from mobile sources nationwide. Although military sector fuel use accounts for only ?0.4% of distillate fuel use in US, emissions factors measured for these engines improve the representation of the relatively small (as compared to onroad sources) database of nonroad emission factors. Heavy-duty multi-axle, all-wheel drive military trucks are not compatible with regular single-axle dynamometers and their emissions cannot be measured under standard laboratory conditions. We have developed a novel in-plume technique to measure in-use emissions from vehicles with elevated stack. Real-world gaseous and particulate matter (PM) emission factors (EFs) from ten 7-ton 6-wheel drive trucks and two 8-wheel drive heavy tactical Logistics Vehicle System (LVS) vehicles were measured using in-plume sampling. The EFs of these trucks are comparable to those of onroad trucks while the PM EFs of 2-stroke LVS are ?10 times higher than those of onroad vehicles. Lower EC/PM ratio was observed for LVS compared with MTVR. PM number emission factors were 5.9 × 10 14 particles km -1 for the trucks and 2.5 × 10 16 particles km -1 for the LVSs, three orders of magnitude higher than the proposed European Union standard of 6 × 10 11 particles km -1. The EFs sampled can be extended to engines used in the broader nonroad sector including agriculture and mining and used as inputs to the NONROAD model.

Zhu, Dongzi; Nussbaum, Nicholas J.; Kuhns, Hampden D.; Chang, M.-C. Oliver; Sodeman, David; Moosmüller, Hans; Watson, John G.

2011-05-01

232

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

Microsoft Academic Search

Trees are effective in the capture of particles from urban air to the extent that they can significantly improve urban air quality. As a result of their aerodynamic properties conifers, with their smaller leaves and more complex shoot structures, have been shown to capture larger amounts of particle matter than broadleaved trees. This study focuses on the effects of particle

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

2005-01-01

233

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 ...

234

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 ...

235

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

236

Prototype development and testing of ultrafine grain NZP ceramics. Final report, July 28, 1995--April 27, 1997  

SciTech Connect

The goal of this project was to demonstrate that a new low-expanding ceramic (Ca{sub 0.6},Mg{sub 0.4})Zr{sub 4}(PO{sub 4}){sub 6}, hereafter referred to as CMZP, could be used as an exhaust manifold liner in off-road diesel engines and provide improved engine efficiency (by permitting higher engine operating temperature). This study has successfully demonstrated this improvement and further engine testing (and possible manufacturing) is presently underway at Caterpillar Inc. Laboratories. Basically this program involved two subcontracts: one to Virginia Tech to develop sintering procedures for CMZP, and one to Caterpillar, Inc. to develop slip casting procedures for CMZP. Nearly 100kg of CMZP were prepared by MATVA, Inc. and Virginia Tech for use by Caterpillar. Virginia Tech developed detailed sintering procedures for CMZP and Caterpillar developed slip casting procedures and manufactured several exhaust manifold elbows. These elbows have been cast into prototype cylinder heads and have been shown to be acceptable replacements for metal manifolds. (Caterpillar advises that a new component may require up to 6 years of testing and qualification before acceptance as standard diesel engine part).

Brown, J.J.

1997-08-04

237

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. PMID:18202315

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

238

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

239

Numerical investigation of the influence of crystallization of ultrafine particles of aluminum oxide on energy characteristics of solid-propellant rocket engine  

NASA Astrophysics Data System (ADS)

The results of numerical investigation of a multiphase flow considering coagulation, crushing and crystallization of the particles of polydispersed condensate in the nozzles of solid-propellant rocket engine are presented. The influence of particles crystallization on the energy characteristics of the engine is shown.

Dyachenko, N. N.; Dyachenko, L. I.

2014-08-01

240

EFFECT OF CENTRAL FANS AND IN-DUCT FILTERS ON DEPOSITION RATES OF ULTRAFINE AND FINE PARTICLES IN AN OCCUPIED TOWNHOUSE  

EPA Science Inventory

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 duct...

241

Respiratory effects of fine and ultrafine particles from indoor sources--a randomized sham-controlled exposure study of healthy volunteers.  

PubMed

Particulate air pollution is linked to impaired respiratory health. We analyzed particle emissions from common indoor sources (candles burning (CB), toasting bread (TB), frying sausages (FS)) and lung function in 55 healthy volunteers (mean age 33.0 years) in a randomized cross-over controlled exposure study. Lung-deposited particle surface area concentration (PSC), size-specific particle number concentration (PNC) up to 10 µm, and particle mass concentration (PMC) of PM1, PM2.5 and PM10 were determined during exposure (2 h). FEV1, FVC and MEF25%-75% was measured before, 4 h and 24 h after exposure. Wilcoxon-rank sum tests (comparing exposure scenarios) and mixed linear regression using particle concentrations and adjusting for personal characteristics, travel time and transportation means before exposure sessions were performed. While no effect was seen comparing the exposure scenarios and in the unadjusted model, inverse associations were found for PMC from CB and FS in relation to FEV1 and MEF25%-75%. with a change in 10 µg/m3 in PM2.5 from CB being associated with a change in FEV1 of -19 mL (95%-confidence interval:-43; 5) after 4 h. PMC from TB and PNC of UFP were not associated with lung function changes, but PSC from CB was. Elevated indoor fine particles from certain sources may be associated with small decreases in lung function in healthy adults. PMID:25000149

Soppa, Vanessa J; Schins, Roel P F; Hennig, Frauke; Hellack, Bryan; Quass, Ulrich; Kaminski, Heinz; Kuhlbusch, Thomas A J; Hoffmann, Barbara; Weinmayr, Gudrun

2014-07-01

242

High-temperature LDV seed particle development  

NASA Technical Reports Server (NTRS)

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.

1989-01-01

243

Effect of quenching conditions on particle formation and growth in thermal plasma synthesis of fine powders  

Microsoft Academic Search

The vapor-phase synthesis of ultrafine powders in reactive thermal plasma systems is studied. A mathematical model is developed to determine the effect of quenching conditions on the size characteristics of powders produced. The particle nucleation is considered to be due to both condensation of product vapor and surface reaction between adsorbed reactant species. The particle growth is considered to be

Shrikant V. Joshi; Qibin Liang; Jin Y. Park; James A. Batdorf

1990-01-01

244

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

245

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

246

Utility of an alternative bicycle commute route of lower proximity to motorised traffic in decreasing exposure to ultra-fine particles, respiratory symptoms and airway inflammation – a structured exposure experiment  

PubMed Central

Background Bicycle commuting in an urban environment of high air pollution is known to be a potential health risk, especially for susceptible individuals. While risk management strategies aimed to reduce exposure to motorised traffic emissions have been suggested, only limited studies have assessed the utility of such strategies in real-world circumstances. Objectives The potential to lower exposure to ultrafine particles (UFP; < 0.1 ?m) during bicycle commuting by reducing proximity to motorised traffic was investigated with real-time air pollution and intermittent acute inflammatory measurements in healthy individuals using their typical higher proximity, and an alternative lower proximity, bicycle commute route. Methods Thirty-five healthy adults (mean ± SD: age = 39 ± 11 yr; 29% female) completed two return trips, one each in the condition of their typical route (HIGH) and a pre-determined alternative route of lower proximity to motorised traffic (LOW); proximity being determined by the proportion of on-road cycle paths. Particle number concentration (PNC) and diameter (PD) were monitored in-commute in real-time. Acute inflammatory indices of respiratory symptoms (as a scalar of frequency from very low to very high / 1 to 5), lung function and spontaneous sputum (for inflammatory cell analyses) were collected immediately pre-commute, and immediately and three hours post-commute. Results In the condition of LOW, compared to in the condition of HIGH, there was a significant decrease in mean PNC (1.91 x e4 ± 0.93 × e4 ppcc vs. 2.95 × e4 ± 1.50 × e4 ppcc; p ? 0.001), and the mean frequency of in-commute offensive odour detection (2.1 vs. 2.8; p = 0.019), dust and soot observation (1.7 vs. 2.3; p = 0.038) and nasopharyngeal irritation (1.5 vs. 1.9; p = 0.007). There were no significant differences between LOW and HIGH in the commute distance and duration (12.8 ± 7.1 vs. 12.0 ± 6.9 km and 44 ± 17 vs. 42 ± 17 min, respectively), or other indices of acute airway inflammation. Conclusions Exposure to PNC and offensive odour, and nasopharyngeal irritation, can be significantly lowered when utilising a route of lower proximity to motorised traffic whilst bicycle commuting, without significantly affecting commute distance or duration. This may bring health benefits for both healthy and susceptible individuals. PMID:23566176

2013-01-01

247

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

248

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

249

Personal exposure to ultrafine particles: Two-level statistical modeling of background exposure and time-activity patterns during three seasons.  

PubMed

Personal exposure to air pollution is associated with time- and location-specific factors including indoor and outdoor air pollution, meteorology and time activities. Our investigation aims at the description and identification of factors determining personal exposure to particle number concentration (PNC) in everyday situations. Ten volunteers recorded their personal exposure to PNC and kept an activity diary in three different seasons besides stationary measurements of ambient air pollution and meteorology. Background exposure to PNC was modelled using the most predictive variables. In a second step, the effects of the activities were calculated adjusted for the background exposure. The average personal PNC level was highest in winter and was three times higher than the mean stationary PNC level while staying indoors and two times higher while staying outdoors. Personal indoor PNC levels were significantly increased during the use of candles, cooking and the occurrence of smell of food. High stationary outdoor PNC levels and low dew point temperatures were associated with increased personal outdoor PNC levels. Times spent in public transport were associated with lower personal PNC levels than other times spent in transportation. Personal PNC levels in everyday situations exhibited a large variability because of seasonal, microenvironment-specific and activity-specific influences.Journal of Exposure Science and Environmental Epidemiology advance online publication, 19 November 2014; doi:10.1038/jes.2014.73. PMID:25407347

Deffner, Veronika; Küchenhoff, Helmut; Maier, Verena; Pitz, Mike; Cyrys, Josef; Breitner, Susanne; Schneider, Alexandra; Gu, Jianwei; Geruschkat, Uta; Peters, Annette

2014-11-19

250

Effects of ultrafine petrol exhaust particles on cytotoxicity, oxidative stress generation, DNA damage and inflammation in human A549 lung cells and murine RAW 264.7 macrophages.  

PubMed

Air pollution has persistently been the major cause of respiratory-related illness and death. Environmental pollutants such as diesel and petrol exhaust particles (PEPs) are the major contributors to urban air pollution. The aim of the present study was to characterize and investigate the in vitro cytotoxicity, oxidative stress, DNA damage and inflammation induced by PEPs. Cultured type II epithelium cells (human A549 lung cells) and alveolar macrophages (murine RAW 264.7 cells) were exposed to control, vehicle control and to different concentrations of PEPs for up to 24h. Each treatment was evaluated by cell viability, cytotoxicity, oxidative stress, DNA damage and inflammatory parameters. Overall in vitro studies demonstrated that both cell lines showed similar patterns in response to the above studies induced by petrol exhaust nanoparticles (PENPs). Vehicle control showed no changes compared with the control. In both cell lines, significant changes at the dose of 20 and 50?g/mL (A549 cell lines) and 10and 20?g/mL (macrophages) for PENPs were found. The reactive oxygen species production in both cell lines shot up in minutes, reached the maximum within an hour and came down after 4h. Hence, exposure to PENPs resulted in dose-dependent toxicity in cultured A549 cells and RAW 264.7 cells and was closely correlated to increased oxidative stress, DNA damage and inflammation. PMID:25173103

Durga, Mohan; Nathiya, Soundararajan; Rajasekar, Abbu; Devasena, Thiyagarajan

2014-09-01

251

Sintering of Ultrafine Metal Powders. I. Coalescence Growth Stage of Au and Ag  

Microsoft Academic Search

Sintering of ultrafine powders of Au and Ag, produced by a gas evaporation technique, has been studied by the electron microscopy and X-ray diffraction methods. The critical temperature, above which the particle size increases, is found to be room temperature for Au powders and 60°C for Ag powders with a particle size of about 200 Å. Retardation of sintering is

Saburo Iwama; Toshio Sahashi

1980-01-01

252

In-situ loading ultrafine AuPd particles on ceria: highly active catalyst for solvent-free selective oxidation of benzyl alcohol.  

PubMed

Ce(III) oxide was synthesized under the protection of nitrogen gas, which had strong ability to reduce noble metal ions (e.g., Au, Pd ions) into metallic forms under oxygen-free conditions. On the basis of the surface redox reaction between the Ce(III) oxide support and noble metal ions, an effective and novel approach was presented to prepare noble metal/CeO(2) nanocatalysts, and a series of AuPd/CeO(2) nanocomposites with different Au:Pd molar ratios and metal loadings were obtained in the absence of any extra reducing and protective agents. The resultant composites were characterized by different techniques including X-ray diffraction, transmission electron microspectroscopy, X-ray photoelectron microspectroscopy, and ICP-AES analysis. It was demonstrated that in the AuPd/CeO(2) composites the content of Ce(III) reached about 30%, and the AuPd bimetallic particles with average size of 2.6 or 3.3 nm and narrow size distribution were uniformly distributed on the CeO(2) nanorods. The AuPd/CeO(2) composites were found to be excellent heterogeneous nanocatalysts for the selective oxidation of benzyl alcohol under solvent-free conditions. It was shown that all the AuPd/CeO(2) catalysts exhibited good selectivity toward benzaldehyde; especially, the catalyst with Au:Pd = 1:5 and metal loading of 1.2 wt % displayed extremely high activity with a TOF = 30.1 s(-1) at 160 °C. PMID:21182245

Zhang, Hongye; Xie, Yun; Sun, Zhenyu; Tao, Ranting; Huang, Changliang; Zhao, Yanfei; Liu, Zhimin

2011-02-01

253

Development of Quality Control Parameters and Electronic Data Recording for an Ambient Air Particle Inhalation Exposure System  

EPA Science Inventory

Ambient air particle concentrating systems were installed by the US EPA in RTP, NC. These systems, designed by Harvard School of Public Health?s Department of Environmental Sciences and Engineering (Boston, MA), concentrated ambient fine and ultra-fine mode particulate matter (P...

254

Seasonal and spatial variation in reactive oxygen species activity of quasi-ultrafine particles (PM0.25) in the Los Angeles metropolitan area and its association with chemical composition  

NASA Astrophysics Data System (ADS)

Seasonal and spatial variation in redox activity of quasi-ultrafine particles (PM0.25) and its association with chemical species was investigated at 9 distinct sampling sites across the Los Angeles metropolitan area. Biologically reactive oxygen species (ROS) assay (generation of ROS in rat alveolar macrophage cells) was employed in order to assess the redox activity of PM0.25 samples. Seasonally, fall and summer displayed higher volume-based ROS activity (i.e. ROS activity per unit volume of air) compared to spring and winter. ROS levels were generally higher at near source and urban background sites compared to rural receptor locations, except for summer when comparable ROS activity was observed at the rural receptor sites. Univariate linear regression analysis indicated association (R > 0.7) between ROS activity and organic carbon (OC), water soluble organic carbon (WSOC) and water soluble transition metals (including Fe, V, Cr, Cd, Ni, Zn, Mn, Pb and Cu). A multivariate regression method was also used to obtain a model to predict the ROS activity of PM0.25, based on its water-soluble components. The most important species associated with ROS were Cu and La at the source site of Long Beach, and Fe and V at urban Los Angeles sites. These metals are tracers of road dust enriched with vehicular emissions (Fe and Cu) and residual oil combustion (V and La). At Riverside, a rural receptor location, WSOC and Ni (tracers of secondary organic aerosol and metal plating, respectively) were the dominant species driving the ROS activity. At Long Beach, the multivariate model was able to reconstruct the ROS activity with a high coefficient of determination (R2 = 0.82). For Los Angeles and Riverside, however, the regression models could only explain 63% and 68% of the ROS activity, respectively. The unexplained portion of the measured ROS activity is likely attributed to the nature of organic species not captured in the organic carbon (OC) measurement as well as non-linear effects, which were not included in our linear model.

Saffari, Arian; Daher, Nancy; Shafer, Martin M.; Schauer, James J.; Sioutas, Constantinos

2013-11-01

255

Protective effects of pulmonary epithelial lining fluid on oxidative stress and DNA single-strand breaks caused by ultrafine carbon black, ferrous sulphate and organic extract of diesel exhaust particles  

SciTech Connect

Pulmonary epithelial lining fluid (ELF) is the first substance to make contact with inhaled particulate matter (PM) and interacts chemically with PM components. The objective of this study was to determine the role of ELF in oxidative stress, DNA damage and the production of proinflammatory cytokines following physicochemical exposure to PM. Ultrafine carbon black (ufCB, 15 nm; a model carbonaceous core), ferrous sulphate (FeSO{sub 4}; a model transition metal) and a diesel exhaust particle (DEP) extract (a model organic compound) were used to examine the acellular oxidative potential of synthetic ELF and non-ELF systems. We compared the effects of exposure to ufCB, FeSO{sub 4} and DEP extract on human alveolar epithelial Type II (A549) cells to determine the levels of oxidative stress, DNA single-strand breaks and interleukin-8 (IL-8) production in ELF and non-ELF systems. The effects of ufCB and FeSO{sub 4} on the acellular oxidative potential, cellular oxidative stress and DNA single-strand breakage were mitigated significantly by the addition of ELF, whereas there was no decrease following treatment with the DEP extract. There was no significant effect on IL-8 production following exposure to samples that were suspended in ELF/non-ELF systems. The results of the present study indicate that ELF plays an important role in the initial defence against PM in the pulmonary environment. Experimental components, such as ufCB and FeSO{sub 4}, induced the production of oxidative stress and led to DNA single-strand breaks, which were moderately prevented by the addition of ELF. These findings suggest that ELF plays a protective role against PM-driven oxidative stress and DNA damage. -- Highlights: ? To determine the role of ELF in ROS, DNA damage and IL-8 after exposure to PM. ? ufCB, FeSO{sub 4} and DEP extract were used to examine the protective effects of ELF. ? PM-driven oxidative stress and DNA single-strand breakage were mitigated by ELF. ? The findings suggest that ELF has a protective role against PM. ? The synthetic ELF system could reduce the use of animals in PM-driven ROS testing.

Chuang, Hsiao-Chi [School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan (China) [School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan (China); Cheng, Yi-Ling; Lei, Yu-Chen [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China)] [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Chang, Hui-Hsien [Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China)] [Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Cheng, Tsun-Jen, E-mail: tcheng@ntu.edu.tw [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China) [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China)

2013-02-01

256

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

257

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

258

Ultrafine coal single stage dewatering and briquetting process  

SciTech Connect

The primary goal of the current physical coal cleaning process is to reduce the ash and sulfur content from the coal, that is, to remove the mineral particles from the coal. In order to separate mineral from coal particles efficiently, the finely disseminated mineral matter must be liberated from the coal matrix with the help of an ultrafine grinding operation. The coal becomes very difficult to dewater because of the small particle size produced. Difficulty in coal transportation as well as in its storage and handling at the utility plants are also problems associated with the small coal particles resulting from ultrafine grinding. During this project, several types of coal samples with various particle size distributions have been tested for use in the dewatering and briquetting processes. Furthermore, various bitumen emulsions have been tested to determine the optimum dewatering reagent. These dewatering and pelletizing tests were carried out using a lab-scale hydraulic compacting device. Discharge from the dewatering and briquetting processes was tested to determine compliance with current federal and state requirements. The influence of bitumen emulsion on the sulfur content of coal pellets made were also examined. In addition, a ram extruder which can be operated continuously to simulate a rotary press operation, has been built and is currently being tested for use in the fine coal dewatering and pelletizing process.

Wilson, J.W.; Ding, Y.; Tobey, M. [Univ. of Missouri, Rolla, MO (United States). Mining Engineering Dept.

1995-12-31

259

Simultaneously strong and tough ultrafine continuous nanofibers.  

PubMed

Strength of structural materials and fibers is usually increased at the expense of strain at failure and toughness. Recent experimental studies have demonstrated improvements in modulus and strength of electrospun polymer nanofibers with reduction of their diameter. Nanofiber toughness has not been analyzed; however, from the classical materials property trade-off, one can expect it to decrease. Here, on the basis of a comprehensive analysis of long (5-10 mm) individual polyacrylonitrile nanofibers, we show that nanofiber toughness also dramatically improves. Reduction of fiber diameter from 2.8 ?m to ?100 nm resulted in simultaneous increases in elastic modulus from 0.36 to 48 GPa, true strength from 15 to 1750 MPa, and toughness from 0.25 to 605 MPa with the largest increases recorded for the ultrafine nanofibers smaller than 250 nm. The observed size effects showed no sign of saturation. Structural investigations and comparisons with mechanical behavior of annealed nanofibers allowed us to attribute ultrahigh ductility (average failure strain stayed over 50%) and toughness to low nanofiber crystallinity resulting from rapid solidification of ultrafine electrospun jets. Demonstrated superior mechanical performance coupled with the unique macro-nano nature of continuous nanofibers makes them readily available for macroscopic materials and composites that can be used in safety-critical applications. The proposed mechanism of simultaneously high strength, modulus, and toughness challenges the prevailing 50 year old paradigm of high-performance polymer fiber development calling for high polymer crystallinity and may have broad implications in fiber science and technology. PMID:23464637

Papkov, Dimitry; Zou, Yan; Andalib, Mohammad Nahid; Goponenko, Alexander; Cheng, Stephen Z D; Dzenis, Yuris A

2013-04-23

260

STRUCTURE AND MECHANICAL PROPERTIES ULTRA-FINE GRAINED TITANIUM  

E-print Network

This paper describes manufacture of ultra-grained titanium, its structure and properties. Ultragrained titanium has higher specific strength properties than ordinary (coarse-grained) titanium. Ultra-grained titanium was produced by the ECAP process. The research it self was focused on physical base of strengthening and softening processes and developments occurring at the grain boundaries during the ECAP process at half-hot temperature. Strength of ultra-fine grained titanium varies around 960 MPa, grain size around 300 nm.

Miroslav Greger; Milena Widomská

261

ENHANCED DETECTION OF 1 NM CONDENSATION NUCLEI USING DIETHYLENE GLYCOL AND BUTANOL CONDENSATION PARTICLE COUNTERS  

E-print Network

ENHANCED DETECTION OF 1 NM CONDENSATION NUCLEI USING DIETHYLENE GLYCOL AND BUTANOL CONDENSATION directly through scattering and absorbing incoming solar radiation and indirectly as cloud condensation. A diethylene glycol-based ultrafine condensation particle counter (DEG-UCPC) has recently been developed

262

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

263

Ultrafine cement grout for sealing underground nuclear waste repositories  

SciTech Connect

Sealing fractures in nuclear waste repositories concerns all programs investigating deep burial as a means of disposal. Because the most likely mechanism for contaminant migration is by dissolution and movement through groundwater, sealing programs are seeking low-viscosity sealants that are chemically, mineralogically, and physically compatible with their host. This paper presents the results of collaborative work between Whitesell Laboratories, operated by Atomic Energy of Canada, Ltd., and Sandia National Laboratories; the work was undertaken in support of the Waste Isolation Pilot Plant (WIPP). This effort addresses the technology associated with long-term isolation of nuclear waste in a natural salt medium. The work presented is part of the plugging and sealing program, specifically the development and optimization of Ultrafine cementitious grout that can be injected to adequately lower excessive, strain-induced permeability in the Distributed Rock Zone (DRZ) surrounding underground excavations. Innovative equipment and procedures employed in the laboratory produced a usable cement-based grout whose particles are 90% smaller than 8 microns and average 4 microns. The process involved simultaneous wet pulverization and mixing. The grout was used for a successful in situ test underground at the WIPP. Injection of grout sealed microfractures as small as 8 microns and lowered the gas permeability of the DRZ by three orders of magnitude. Following the WIPP test, additional work produced an improved version of the grout containing particles 90% smaller than 6 microns and averaging 2 microns. This grout can be produced in the dry form at a competitive cost ready to mix.

Ahrens, E.H. [Sandia National Labs., Livermore, CA (United States); Onofrei, M. [Atomic Energy of Canada Ltd., Pinawa, MB (Canada). Whiteshell Nuclear Research Establishment

1996-02-01

264

Ultrafine coal single stage dewatering and briquetting process  

SciTech Connect

It is well known that a large portion of the pyrite particles in the coal seams of the Illinois Basin are finely disseminated within the coal matrix. In order to liberate these micron size pyrite particles, one must use a fine grinding operation. The ultrafine coal particles are difficult to dewater and create problems in coal transportation, as well as in storage and handling at utility plants. The objective of this research project is to combine the ultrafine coal dewatering and briquetting processes into a single stage operation. This will be accomplished by the use of bitumen based emulsions for dewatering and a compaction device for briquetting. During this reporting period, several types of coal samples with various particle size distributions have been tested for use in the dewatering and briquetting processes. Furthermore, various bitumen emulsions have been tested to determine the optimum dewatering reagent. These dewatering and pelletizing tests were carried out using a lab-scale ram extruder. Discharge from the dewatering and briquetting processes was tested to determine compliance with current federal and state requirements. The influence of bitumen emulsion on the sulfur content of coal pellets made were also examined. In addition, a ram extruder which can be operated continuously to simulate a rotary press operation, has been built and is currently being tested for use in the fine coal dewatering and pelletizing process.

Wilson, J.W. [Missouri Univ., Rolla, MO (United States). Dept. of Mining Engineering; Honaker, R.Q. [Southern Illinois Univ., Carbondale, IL (United States). Dept. of Mining Engineering

1995-12-31

265

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

266

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

267

Preparation of ultrafine boride powders by metallothermic reduction method  

Microsoft Academic Search

Ultrafine TiB2, ZrB2, and ReB2 powders were prepared by the metallothermic reduction method using Mg. Obtained TiB2, ZrB2, and ReB2 powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and scratch test. The morphology of the powders was a laminar hexagonal single crystal. The mean particle sizes of TiB2 and ZrB2 increased with increasing

Katsuhiro Nishiyama; Takanobu Nakamur; Shigenori Utsumi; Hideki Sakai; Masahiko Abe

2009-01-01

268

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

269

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

270

24-gauge ultrafine cryoprobe with diameter of 550?m and its cooling performance.  

PubMed

This paper describes the development of a novel cryoprobe with the same size as a 24-gauge injection needle and the evaluation of its cooling performance. This ultrafine cryoprobe was designed to reduce the invasiveness and extend application areas of cryosurgery. The ultrafine cryoprobe has a double-tube structure and consists of two stainless steel microtubes. The outer diameter of the cryoprobe is 550?m, and the inner tube has a 70-?m inner diameter to depressurize the high-pressure refrigerant. By solving the bioheat transfer equation and considering freezing phenomena, the relationship between the size of the frozen region and the heat transfer coefficient of the refrigerant flow in an ultrafine cryoprobe was derived analytically. The results showed that the size of the frozen region is strongly affected by the heat transfer coefficient. A high heat transfer coefficient such as that of phase change heat transfer is required to generate a frozen region of sufficient size. In the experiment, trifluoromethane (HFC-23) was used as the refrigerant, and the cooling effects of the gas and liquid phase states at the inlet were evaluated. When the ultrafine cryoprobe was cooled using a liquid refrigerant, the surface temperature was approximately -50°C, and the temperature distribution on the surface was uniform for a thermally insulated condition. However, for the case with vaporized refrigerant, the temperature distribution was not uniform. Therefore, it was concluded that the cooling mechanism using liquid refrigerant was suitable for ultrafine cryoprobes. Furthermore, to simulate cryosurgery, a cooling experiment using hydrogel was conducted. The results showed that the surface temperature of the ultrafine cryoprobe reached -35°C and formed a frozen region with a radius of 4mm in 4min. These results indicate that the ultrafine cryoprobe can be applied in actual cryosurgeries for small affected areas. PMID:25305055

Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao

2014-12-01

271

Particle acceleration in time-developing magnetic reconnection process  

Microsoft Academic Search

Particle trajectories and acceleration are numerically studied in time-varying electric and magnetic fields that are obtained by a previous MHD simulation of an externally driven reconnection. Electron and proton orbits are traced under the influence of the developing reconnection fields for various initial particle positions and velocities. A method of continuation of local analytic solution in a particle-pushing algorithm is

Tetsuya Sato; Hiroshi Matsumoto; Keisuke Nagai

1982-01-01

272

Fluid particle accelerations in fully developed turbulence  

Microsoft Academic Search

The motion of fluid particles as they are pushed along erratic trajectories\\u000aby fluctuating pressure gradients is fundamental to transport and mixing in\\u000aturbulence. It is essential in cloud formation and atmospheric transport,\\u000aprocesses in stirred chemical reactors and combustion systems, and in the\\u000aindustrial production of nanoparticles. The perspective of particle\\u000atrajectories has been used successfully to describe mixing

Greg A. Voth; Alice M. Crawford; Jim Alexander; Eberhard Bodenschatz; A. La Porta

2001-01-01

273

Discharge-aided reactive laser ablation for ultrafine powder production  

NASA Astrophysics Data System (ADS)

Ultrafine alumina powder was produced by aluminum target ablation with a Nd:YAG laser beam (1064 nm wavelength; 340 mJ/pulse energy; 7 ns pulse duration; 10 pps repetition rate), in a 120 Torr O2 atmosphere. A theoretical approach for the ablation process, based on laser energy absorption and energy balance in the target, is used for comparison with the experimental production rate. Three experimental irradiation conditions were chosen: (1) energy density of 5 J/cm2, considered reference (RDE), (2) lower energy density of 2.5 J/cm2 (LDE) and (3) RDE with auxiliary discharge between an auxiliary electrode and target, triggered by the ablation plume (RDA). Calculated and experimental data of target weight loss show good agreement (135 ng/pulse, calculated, and 100, 110, 120 ng/pulse, experimentally, for RDE, LDE, RDA conditions, respectively). The X-Ray Diffraction spectra of alumina show formation of (gamma) -alumina particles only, especially in LDE and RDA conditions. From Scanning Electron Microscopy size analysis, a decrease of particle size, in LDE and RDA irradiating conditions, is observed. The decrease of laser beam fluence or aiding of ablation using an auxiliary discharge is both favorable for the production of high quality powder, without diminishing the production rate. This can be a good basis for future improvement of the ultrafine powder production process.

Chis, Ioan; Marcu, Aurelian; Yukawa, T.; Dragulinescu, Dumitru; Grigoriu, Constantin; Miu, Dana; Jiang, Weihua; Yatsui, Kiyoshi

1998-07-01

274

Sintering behavior of ultrafine silicon carbide powders obtained by vapor phase reaction  

NASA Technical Reports Server (NTRS)

The sintering behavior of ultrafine SiC powder with average particle size of about 0.01-0.06 microns produced by a vapor phase reaction of the Me4Si-H2 system was studied at the temperature range of 1400-2050 deg. It was found that the homogeneous dispersion of C on SiC particles is important to remove the surface oxide layer effectively. B and C and inhibitive effect on SiC grain growth.

Okabe, Y.; Miyachi, K.; Hojo, J.; Kato, A.

1984-01-01

275

Processing, application and characterization of ultrafine 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, ultrafine 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) ultrafine 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 several of these topics will be highlighted in more detail.

van der Heijden, Antoine

2005-07-01

276

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

277

Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite  

PubMed Central

The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties. PMID:25265897

Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, Jürgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem

2014-01-01

278

Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite  

NASA Astrophysics Data System (ADS)

The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties.

Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, Jürgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem

2014-09-01

279

Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite.  

PubMed

The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties. PMID:25265897

Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, Jürgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem

2014-01-01

280

Ultrafine hollow needle formation on silicon  

NASA Astrophysics Data System (ADS)

A method for the formation of ultrafine hollow needles, microcylindrical and nano-wall structures on silicon substrates is reported. The fabrication of these ultrafine structures is possible through a combination of high-precision high aspect ratio vertical etching of silicon with a small angle vacuum deposition technique where nanometric walls are feasible. These structures can be used as the media to transfer gas and liquid through their tiny holes. In addition, the structure has been used to realize cavity-based capacitance inclination sensor suitable for small angle detection. A capacitance variation of 0.6 pF/degree of inclination has been obtained.

Sanaee, Z.; Mohajerzadeh, S.

2010-04-01

281

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

282

Measurement of particle accelerations in fully developed turbulence  

Microsoft Academic Search

We use silicon strip detectors (originally developed for the CLEO III high\\u000aenergy particle physics experiment) to measure fluid particle trajectories in\\u000aturbulence with temporal resolution of up to 70,000 frames per second. This\\u000ahigh frame rate allows the Kolmogorov time scale of a turbulent water flow to\\u000abe fully resolved for 140 <= R_lambda <= 970. Particle trajectories exhibiting

GREG A. VOTH; A. LA PORTA; ALICE M. CRAWFORD; JIM ALEXANDER; EBERHARD BODENSCHATZ

2002-01-01

283

Suppression of methane/air explosion by ultrafine water mist containing sodium chloride additive.  

PubMed

The suppression effect of ultrafine mists on methane/air explosions with methane concentrations of 6.5%, 8%, 9.5%, 11%, and 13.5% were experimentally studied in a closed visual vessel. Ultrafine water/NaCl solution mist as well as pure water mist was adopted and the droplet sizes of mists were measured by phase doppler particle analyzer (PDPA). A high speed camera was used to record the flame evolution processes. In contrast to pure water mist, the flame propagation speed, the maximum explosion overpressure (?Pmax), and the maximum pressure rising rate ((dP/dt)max) decreased significantly, with the "tulip" flame disappearing and the flame getting brighter. The results show that the suppressing effect on methane explosion by ultrafine water/NaCl solution mist is influenced by the mist amount and methane concentration. With the increase of the mist amount, the pressure, and the flame speed both descended significantly. And when the mist amount reached 74.08g/m(3) and 37.04g/m(3), the flames of 6.5% and 13.5% methane explosions can be absolutely suppressed, respectively. All of results indicate that addition of NaCl can improve the suppression effect of ultrafine pure water mist on the methane explosions, and the suppression effect is considered due to the combination effect of physical and chemical inhibitions. PMID:25528229

Cao, Xingyan; Ren, Jingjie; Zhou, Yihui; Wang, Qiuju; Gao, Xuliang; Bi, Mingshu

2015-03-21

284

Spatial development of particle-laden turbulent pipe flow  

NASA Astrophysics Data System (ADS)

The inhomogeneity of turbulence in wall bounded flows induces the phenomenology called turbophoresis whereby inertial particles of suitable mass accumulate at the solid wall. Particles injected near the axis of a fully turbulent pipe flow, after an initial spreading phase, undergo a segregation process which eventually leads to a pseudoequilibrium distribution sufficiently downstream. Wall densities up to thousand times the reference value can be easily achieved. The process is discussed here by analyzing the direct numerical simulation (DNS) data of a spatially developing particle laden pipe flow under the assumption of dilute suspension. Development phase and asymptotic state are addressed in quantitative terms. A Shannon-like entropy is introduced to quantify the level of spreading/segregation achieved by the particle distributions along the pipe. This allows to define on a physically sound basis the length of the developing region and to summarize in a single indicator the accumulation level as a function of the particle response time. By conditional statistics, it is unequivocally shown that particles approach the wall dragged by relatively fast yet comparatively rare events where highly accumulating particles follow the fluid in-rush toward the wall. On the contrary, the outward particle flux takes place in the form of much more frequent and gentle motions away from the wall. The analysis of DNS data and a simple argument highlight the role of the elongated clusters of particles at the wall as essential features responsible for the eventual asymptotic equilibrium.

Picano, F.; Sardina, G.; Casciola, C. M.

2009-09-01

285

Development of a Charged Particle Microbeam for Targeted and Single Particle Subcellular Irradiation  

SciTech Connect

The development of a charged particle microbeam for single particle, subcellular irradiations at the Massachusetts Institute of Technology Laboratory for Accelerator Beam Applications (MIT LABA) was initiated under this NEER aeard. The Microbeam apparatus makes use of a pre-existing electrostatic accelerator with a horizontal beam tube.

Yanch, Jacquelyn C.

2004-03-12

286

Laser wakefield simulations towards development of compact particle accelerators  

E-print Network

Laser wakefield simulations towards development of compact particle accelerators C.G.R. Geddes1, D understanding of accelerator physics to advance beam performance and stability, and particle simulations model, France; 9 Oxford University, UK E-mail: cgrgeddes@lbl.gov Abstract. Laser driven wakefield accelerators

Geddes, Cameron Guy Robinson

287

Status of preparing ultra-fine grained titanium alloys by equal channel angular pressing  

Microsoft Academic Search

Equal channel angular pressing (ECAP), as one of the most feasible severe plastic deformation (SPD) techniques for industry manufacturing, can produce ultra-fine grained (UFG) structures and improve properties and forming ability of titanium alloys. The basic principle, research development and application of preparing UFG titanium alloys were introduced. The effects of different ECAP factors on microstructure and properties, and the

Yan Zhao; Hongzhen Guo; Tao Wang; Zekun Yao

2010-01-01

288

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

289

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

290

Ultrafine coal single stage dewatering and briquetting process. Technical report, September 1--November 30, 1994  

SciTech Connect

It is well known that a large portion of the pyrite particles in the coal seams of the Illinois Basin, are finely disseminated within the coal matrix. In order to liberate these micron size pyrite particles, one must use a fine grinding operation. The ultrafine coal particles that are produced are difficult to dewater and they create problems in coal transportation as well as in its storage and handling at utility plants. The objective of this research project is to combine ultrafine coal dewatering and briquetting processes into a single stage operation. This will be accomplished by the use of bitumen based emulsions for dewatering and a compaction device for briquetting. During this reporting period, two types of coal samples have been tested for use in the dewatering and briquetting processes. These tests were carried out in conjunction with a selected hydrophobic binder as the dewatering reagent and an uniaxial hydraulic press. The influence of compaction pressure and binder concentration (2 to 5%) on the performance of coal pellets have been evaluated in terms of their water and wear resistance. A laboratory scale ultrafine coal dewatering and briquetting extruder that can be operated continuously for coal pellets fabrication, has been designed and built, and will be available for testing in the next quarter.

Wilson, J.W. [Univ. of Missouri, Rolla, MO (United States). Dept. of Mining Engineering; Honaker, R.Q. [Southern Illinois Univ., Carbondale, IL (United States). Dept. of Mining Engineering

1994-12-31

291

Early Postnatal Exposure to Ultrafine Particulate Matter Air Pollution: Persistent Ventriculomegaly, Neurochemical Disruption, and Glial Activation Preferentially in Male Mice  

PubMed Central

Background: Air pollution has been associated with adverse neurological and behavioral health effects in children and adults. Recent studies link air pollutant exposure to adverse neurodevelopmental outcomes, including increased risk for autism, cognitive decline, ischemic stroke, schizophrenia, and depression. Objectives: We sought to investigate the mechanism(s) by which exposure to ultrafine concentrated ambient particles (CAPs) adversely influences central nervous system (CNS) development. Methods: We exposed C57BL6/J mice to ultrafine (< 100 nm) CAPs using the Harvard University Concentrated Ambient Particle System or to filtered air on postnatal days (PNDs) 4–7 and 10–13, and the animals were euthanized either 24 hr or 40 days after cessation of exposure. Another group of males was exposed at PND270, and lateral ventricle area, glial activation, CNS cytokines, and monoamine and amino acid neurotransmitters were quantified. Results: We observed ventriculomegaly (i.e., lateral ventricle dilation) preferentially in male mice exposed to CAPs, and it persisted through young adulthood. In addition, CAPs-exposed males generally showed decreases in developmentally important CNS cytokines, whereas in CAPs-exposed females, we observed a neuroinflammatory response as indicated by increases in CNS cytokines. We also saw changes in CNS neurotransmitters and glial activation across multiple brain regions in a sex-dependent manner and increased hippocampal glutamate in CAPs-exposed males. Conclusions: We observed brain region– and sex-dependent alterations in cytokines and neurotransmitters in both male and female CAPs-exposed mice. Lateral ventricle dilation (i.e., ventriculomegaly) was observed only in CAPs-exposed male mice. Ventriculomegaly is a neuropathology that has been associated with poor neurodevelopmental outcome, autism, and schizophrenia. Our findings suggest alteration of developmentally important neurochemicals and lateral ventricle dilation may be mechanistically related to observations linking ambient air pollutant exposure and adverse neurological/neurodevelopmental outcomes in humans. Citation: Allen JL, Liu X, Pelkowski S, Palmer B, Conrad K, Oberdörster G, Weston D, Mayer-Pröschel M, Cory-Slechta DA. 2014. Early postnatal exposure to ultrafine particulate matter air pollution: persistent ventriculomegaly, neurochemical disruption, and glial activation preferentially in male mice. Environ Health Perspect 122:939–945;?http://dx.doi.org/10.1289/ehp.1307984 PMID:24901756

Allen, Joshua L.; Liu, Xiufang; Pelkowski, Sean; Palmer, Brian; Conrad, Katherine; Oberdörster, Günter; Weston, Douglas; Mayer-Pröschel, Margot

2014-01-01

292

Ultrafine Particulate Ferrous Iron and Anthracene Associations with Mitochondrial Dysfunction  

SciTech Connect

The ultrafine size fraction of ambient particles (ultrafine particles, UFP, diameter < 100 nm) has been identified as being far more potent in their adverse health effects than their larger counterparts, yet, the detailed mechanisms for why UFP display such distinctive toxicity are not well understood. In the present study, ambient UFP were exposed to mitochondria while monitoring electron transport chain (ETC) activity as a model system for biochemical toxicity. UFP samples were collected in rural (Ellensburg, WA) and urban environments (Seattle, WA) and chemically characterized for total trace metals, ferrous (Fe(II)) and easily reducible ferric (Fe(III)) iron, polycyclic aromatic hydrocarbons, and surface constituents with X-ray photoelectron spectroscopy (XPS). Low doses of UFP (8 µg mL-1) caused a decrease in mitochondrial ETC function compared to controls in 94% of the samples after The 20 min of exposure. Significant correlations exist between initial %ETC inhibition (0-10 min) and Fe(II) (R=0.55, P=0.03, N=15), anthracene (R=0.74, P<0.01, N=13), and %C-O surface bonds (R=0.56, P=0.03, N=15), whereby anthracene and %C-O correlate as well (R=0.58, P=0.03, N=14). No significant associations were identified with total Fe and other trace metals. Results from this study indicate that the redox active fraction of Fe as well as the abundance of anthracene-related, C-O containing, surface structures may contribute to the initial detrimental behavior of UFP, thus supporting the idea that the Fe(II)/Fe(III) and certain efficient hydroquinone/quinone redox pairs may play an important role likely due to their potential to produce reactive oxygen species (ROS).

Faiola, Celia; Johansen, Anne M.; Rybka, Sara; Nieber, Annika; Thomas-Bradley, Carin; Bryner, Stephanie; Johnston, Justin M.; Engelhard, Mark H.; Nachimuthu, Ponnusamy; Owens, Kalyn S.

2011-04-20

293

Comparative study of ultrafine atmospheric aerosol within a city  

NASA Astrophysics Data System (ADS)

Particle number size distributions in a mobility diameter range of 6-1000 nm and size-resolved number concentrations were determined with a time resolution of 10 min for a near-city background, city centre, street canyon and road tunnel environments in Budapest. Median N6-100 concentrations for the sites listed were 3.1 × 103, 9.3 × 103, 19.4 × 103 and 123 × 103 cm-3, respectively. Contributions of the ultrafine (UF) particles (<100 nm) to the total particle number for all locations were rather large (up to 86%), and do not seem to vary substantially in time. Diurnal variations of the mean N6-100 concentrations had different patterns for both the various urban sites, and for workdays and weekends. Nucleation strength factor (NSF) was introduced for the first time to quantify the relative importance of new particle formation with respect to all sources of UF particles. During the daytime in summer, nucleation in the near-city background was a major production process of UF particles with a daily mean relative contribution of 42%. In the city centre and street canyon, the daily mean relative contributions of nucleation to the UF particles were 30% and 23%, respectively. Median particle diameters for the background, city centre, street canyon and road tunnel environments were 61, 42, 35 and 42 nm, respectively, so they were jointly influenced with the anthropogenic impact and aerosol ageing. Monthly mean frequency of new particle formation and growth events in the background seems somewhat larger, while it appears smaller for the street canyon in comparison to the city centre.

Salma, I.; Borsós, T.; Németh, Z.; Weidinger, T.; Aalto, P.; Kulmala, M.

2014-08-01

294

Primitive ultrafine matrix in ordinary chondrites  

NASA Technical Reports Server (NTRS)

Ultrafine matrix material has been concentrated by sieving and filtering disaggregated samples of six ordinary chondrites of different classes. This component(s), 'Holy Smoke' (HS), is enriched in both volatile, e.g. Na, K, Zn, Sb, and Pb, as well as refractory elements, e.g. W and REE; however, the element ratios vary greatly among the different chondrites. SEM studies show that HS contains fragile crystals, differing in composition, and apparently in gross disequilibrium not only among themselves but also with the major mineral phases and consequently thermodynamic equilibration did not occur. Thus HS must have originated from impacting bodies and/or was inherent in the 'primitive' regolith. Subsequent impact brecciation and reheating appears to have altered, to varying degrees, the original composition of this ultrafine matrix material. Recent 'cosmic dust' studies may indicate that HS still exists in the solar system. Survival of such delicate material must be considered in all theories for the origin of chondrites.

Rambaldi, E. R.; Fredriksson, B. J.; Fredriksson, K.

1981-01-01

295

The phase of particle acceleration in the flare development  

Microsoft Academic Search

Evidence is given that the particle acceleration in flares is confined to the initial phase of the flare development preceding the Ha flare maximum and lasting for less than 10 min. The impulsive acceleration process is confined to a relatively small limited volume of about 5 × 1027 cm3 in the region of highest magnetic gradient in the flare, and

Z. Švestka

1970-01-01

296

DEVELOPMENT OF SENSITIVE MAGNETIC PARTICLE IMMUNOASSAY FOR POLYBROMINATED DIPHENYL ETHERS.  

Technology Transfer Automated Retrieval System (TEKTRAN)

A sensitive magnetic particle based immunoassay for polybrominated diphenyl ether (PBDE) was developed. Rabbit antiserum was produced by immunizing the rabbit with 4-(2,4-dibromo-5-(2,4-dibromophenoxy)phenoxy)butyrate-BSA. The PBDE ligand and horse radish peroxidase were conjugated via NHS and EDA...

297

Enhanced ultrafine coal dewatering using flocculation filtration processes  

Microsoft Academic Search

Ultrafine coal (?150 ?m) can be effectively cleaned using advanced separation techniques such as column flotation, however, dewatering it to below 20 percent moisture level using the conventional dewatering techniques is difficult. A comparative flocculation filtration study was performed for enhancing dewatering of ultrafine coal using vacuum, hyperbaric, and centrifugal filters. The cationic and anionic flocculants were added into the

D. Tao; J. G. Groppo; B. K. Parekh

2000-01-01

298

Development of a large-area silicon ?-particle detector.  

PubMed

Circular ion-implanted silicon detector of ?-particles with a large, 5-cm(2), sensitive area has been developed. An advantage of the detector is that the detector surface is easily cleanable with chemicals. The hardened surface of the detector shows no signs of deterioration of the spectroscopic and electrical characteristics upon repeated cleaning. The energy resolution along the diameters of the detector was (1.0±0.1)% for the 5.486-MeV ?-particles. Detailed tests of the charge collection efficiency and uniformity of the detector entrance window were also performed with a 5.5-MeV He(2+) microbeam. PMID:25016328

Tran, Linh T; Prokopovich, Dale A; Lerch, Michael L F; Petasecca, Marco; Siegele, Rainer; Reinhard, Mark I; Perevertaylo, Vladimir; Rosenfeld, Anatoly B

2014-09-01

299

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

300

Charged Particle Environment Definition for NGST: Model Development  

NASA Technical Reports Server (NTRS)

NGST will operate in a halo orbit about the L2 point, 1.5 million km from the Earth, where the spacecraft will periodically travel through the magnetotail region. There are a number of tools available to calculate the high energy, ionizing radiation particle environment from galactic cosmic rays and from solar disturbances. However, space environment tools are not generally available to provide assessments of charged particle environment and its variations in the solar wind, magnetosheath, and magnetotail at L2 distances. An engineering-level phenomenology code (LRAD) was therefore developed to facilitate the definition of charged particle environments in the vicinity of the L2 point in support of the NGST program. LRAD contains models tied to satellite measurement data of the solar wind and magnetotail regions. The model provides particle flux and fluence calculations necessary to predict spacecraft charging conditions and the degradation of materials used in the construction of NGST. This paper describes the LRAD environment models for the deep magnetotail (XGSE < -100 Re) and solar wind, and presents predictions of the charged particle environment for NGST.

Blackwell, William C.; Minow, Joseph I.; Evans, Steven W.; Hardage, Donna M.; Suggs, Robert M.

2000-01-01

301

Susceptibility to Inhaled Flame-Generated Ultrafine Soot in Neonatal and Adult Rat Lungs  

PubMed Central

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.

2011-01-01

302

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

303

Virus-like particles in picornavirus vaccine development.  

PubMed

Virus-like particles (VLP), which are similar to natural virus particles but do not contain viral genes, have brought about significant breakthroughs in many research fields because of their unique advantages. The ordered repeating epitopes of VLP can induce immunity responses similar to those prompted by natural viral infection; thus, VLP vaccines are regarded as candidate alternatives to whole-virus vaccines. As picornavirus has serious impacts on human and animal health, the development of efficient and safe vaccines is a key endeavor in preventing virus infections. The characteristics of picornavirus capsid proteins allow the development of VLP vaccines. This paper investigates research scenarios and progress on picornavirus VLP vaccines with the aim of providing a reference for researchers focusing on virology and vaccinology. PMID:24647496

Dong, Hu; Guo, Hui-Chen; Sun, Shi-Qi

2014-05-01

304

Synthesis of Ultrafine Carbon Black by Pyrolysis of Polymers Using a Direct Current Thermal Plasma Process  

Microsoft Academic Search

A direct current thermal plasma system was developed and applied to synthesize ultrafine carbon black by using PS (polystyrene)\\u000a and HDPE (high density polyethylene) as carbon sources. The precursors were pyrolyzed at different temperatures and the pyrolysis\\u000a products were employed to investigate the actual synthesis of carbon black through the plasma jet. Spherical carbon nanoparticles\\u000a with a high degree of

Xiao-Feng Guo; Geon-Joong Kim

2010-01-01

305

Photocatalytic water splitting using semiconductor particles: History and recent developments  

Microsoft Academic Search

Overall water splitting to produce H2 and O2 over a semiconductor photocatalyst using solar energy is a promising process for the large-scale production of clean, recyclable H2. Numerous attempts have been made to develop photocatalysts that function under visible-light irradiation to efficiently utilize solar energy. In general, overall water splitting over a photocatalyst particle can be achieved by modifying the

Kazuhiko Maeda

306

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

307

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

308

Ultrafine coal single stage dewatering and briquetting process. Technical report, December 1, 1994--February 28, 1995  

SciTech Connect

It is well known that a large portion of the pyrite particles in the coal seams of the Illinois Basin, are finely disseminated within the coal matrix. In order to liberate these micron size pyrite particles, one must use a fine grinding operation. The ultrafine coal particles that are produced are difficult to dewater and they create problems in coal transportation as well as in its storage and handling at utility plants. The objective of this research project is to combine ultrafine coal dewatering and briquetting processes into a single stage operation. This will be accomplished by the use of bitumen based emulsions for dewatering and a compaction device for briquetting. During this reporting period, two types of coal samples have been tested for use in the dewatering and briquetting processes. These tests were carried out using Orimulsion as the dewatering reagent. A ram extruder that can be operated continuously is used to fabricate dewatered pellets. The influence of compaction pressure, curing time, binder concentration (2% to 5%), particle size, and compacting time on the performance of coal pellets have been evaluated in terms of their water resistance and wear vulnerability.

Wilson, J.W.

1996-03-01

309

Principle and equipment of polymer melt differential electrospinning preparing ultrafine fiber  

NASA Astrophysics Data System (ADS)

Two methods preparing polymer ultrafine fiber have been developed: solution electrospinning and melt electrospinning, among which, solution electrospinning is much simpler to realize in lab or industry. More than 100 institutions have made endeavors to research it and more than 30 thousand papers have been published. However, its industrialization was restricted in some extend because of existence of toxic solvent and low strength caused by small pores. Solventless melt electrospinning is environment friendly, but high melt viscosity, thick fiber diameter, low yield and complex equipment lead to less research on it. Aiming to solving the shortage of traditional needle nozzle equipment, we first proposed a melt differential electrospinning method preparing ultrafine fiber, through which fiber smaller than imicrometer can be produced and a yield of 10-20g/h can be achieved by a needleless nozzle. Further more, principle and equipment of melt differential electrospinning are introduced.

Weimin, Yang; Haoyi, Li

2014-08-01

310

Recently developed methods in neutral-particle transport calculations: Overview  

NASA Astrophysics Data System (ADS)

Successful, general methods for the solution of the neutral particle transport equation involve a close connection between the spatial discretization method used and the source acceleration method chosen. The first form of the transport equation, angular discretization (which is discrete ordinates) is considered as well as spatial discretization based upon a mesh arrangement. Characteristic methods are considered briefly in the context of future, desirable developments. The ideal spatial discretization method is described as having the following attributes: positive-positive boundary data yields a positive angular flux within the mesh including its boundaries; satisfies the particle balance equation over the mesh, that is, the method is conservative; possesses the diffusion limit independent of spatial mesh size, that is for a linearly isotropic flux assumption, the transport differencing reduces to a suitable diffusion equation differencing; the method is unconditionally acceleratable, i.e., for each mesh size, the method is unconditionally convergent with a source iteration acceleration.

Alcouffe, R. E.

311

Particle morphological and roughness controls on mineral surface charge development  

NASA Astrophysics Data System (ADS)

Effects of mineral particle morphology and roughness on potential determining ion (p.d.i.; H+, OH-) loadings achieved at synthetic lepidocrocite (?-FeOOH) surfaces were predominantly investigated by potentiometry and thermodynamic modeling. Nanosized rod- (RL) and lath-shaped (LL) particles exhibiting different proportions of the same predominant crystallographic faces acquired largely comparable pH, ionic strength and counterion (NaCl, NaClO4) dependencies on p.d.i. loadings. These results supported previous claims that faces ideally containing proton silent sites only, are likely populated by additional proton active sites. This concept was supported further by results of roughened LL-like particles (LLR) also showing highly congruent pH-, ionic strength- and composition-dependent p.d.i. loadings with those of LL and RL. These loadings thereby correspond to maximal levels allowed by net attractive and repulsive forces at each solution composition, irrespective of particle morphology. Contrasting equilibration times required to achieve these loadings revealed considerably slower exchange of p.d.i. and electrolyte ions near the point of zero charge in the rough LLR than in the more idealized LL and RL particles. Thermodynamic modeling was used to test various concepts accounting for these results. The model made use of a novel framework capable of isolating electrostatic contributions from different faces, and of accounting for ion-specific double-layer properties within a single crystallographic face. These efforts made use of capacitance values for each electrolyte ions within the framework of a recently developed Variable Capacitance Model. Attempts at modeling all three particle types were used to suggest that the (0 1 0) face contains ?0.9 site nm-2 of proton active sites, a value notably constrained by recently published Na+, Cl-, and ClO4- loadings derived by cryogenic X-ray photoelectron spectroscopy. The model presented in this work thus provides a means to predict p.d.i. loadings on multifaceted mineral particle surfaces, and can therefore be used to constrain further our understanding of mineral/water interface reactivity.

Boily, Jean-François; Kozin, Philipp A.

2014-09-01

312

Ultrafine BaFe 12O 19 powder synthesised by mechanochemical processing  

Microsoft Academic Search

Ultrafine BaFe12O19 powder has been synthesised by a novel mechanochemical preparation method. Mechanical milling of 1.2BaCl2 + 12FeCl3 + 38.4NaOH led to a mixture of NaCl and iron and barium hydroxide or oxidehydroxide. The formation of BaFe12O19 required annealing at 800°C in air. A significant reduction of particle size was achieved by dilution with NaCl. High coercivity values above 5

J. Ding; T. Tsuzuki; P. G. McCormick

1998-01-01

313

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

314

Development progress of the Materials Analysis and Particle Probe.  

PubMed

The Materials Analysis and Particle Probe (MAPP) is a compact in vacuo surface science diagnostic, designed to provide in situ surface characterization of plasma facing components in a tokamak environment. MAPP has been implemented for operation on the Lithium Tokamak Experiment at Princeton Plasma Physics Laboratory (PPPL), where all control and analysis systems are currently under development for full remote operation. Control systems include vacuum management, instrument power, and translational/rotational probe drive. Analysis systems include onboard Langmuir probes and all components required for x-ray photoelectron spectroscopy, low-energy ion scattering spectroscopy, direct recoil spectroscopy, and thermal desorption spectroscopy surface analysis techniques. PMID:25430248

Lucia, M; Kaita, R; Majeski, R; Bedoya, F; Allain, J P; Boyle, D P; Schmitt, J C; Onge, D A St

2014-11-01

315

Some recent developments in nuclear charged particle detectors  

SciTech Connect

The latest developments of large-area, position sensitive gas-filled ionization chambers are described. Multi-wire-proportional chambers as position-sensing and parallel-plate-avalanche counters as time-sensing detectors at low pressure (5 torr) have proven to be useful and reliable instruments in heavy ion physics. Gas (proportional) scintillation counters, used mainly for x-ray spectroscopy, have recently been applied as particle detectors. Finally, a brief description of a large plastic scintillator spectrometer, the Plastic Ball, is given and some of the first test and calibration data are shown.

Stelzer, H.

1980-08-01

316

Development progress of the Materials Analysis and Particle Probea)  

NASA Astrophysics Data System (ADS)

The Materials Analysis and Particle Probe (MAPP) is a compact in vacuo surface science diagnostic, designed to provide in situ surface characterization of plasma facing components in a tokamak environment. MAPP has been implemented for operation on the Lithium Tokamak Experiment at Princeton Plasma Physics Laboratory (PPPL), where all control and analysis systems are currently under development for full remote operation. Control systems include vacuum management, instrument power, and translational/rotational probe drive. Analysis systems include onboard Langmuir probes and all components required for x-ray photoelectron spectroscopy, low-energy ion scattering spectroscopy, direct recoil spectroscopy, and thermal desorption spectroscopy surface analysis techniques.

Lucia, M.; Kaita, R.; Majeski, R.; Bedoya, F.; Allain, J. P.; Boyle, D. P.; Schmitt, J. C.; Onge, D. A. St.

2014-11-01

317

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...

318

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

319

Particles induce apical plasma membrane enlargement in epithelial lung cell line depending on particle surface area dose  

PubMed Central

Background Airborne particles entering the respiratory tract may interact with the apical plasma membrane (APM) of epithelial cells and enter them. Differences in the entering mechanisms of fine (between 0.1 ?m and 2.5 ?m) and ultrafine ( ? 0.1 ?m) particles may be associated with different effects on the APM. Therefore, we studied particle-induced changes in APM surface area in relation to applied and intracellular particle size, surface and number. Methods Human pulmonary epithelial cells (A549 cell line) were incubated with various concentrations of different sized fluorescent polystyrene spheres without surface charge (? fine – 1.062 ?m, ultrafine – 0.041 ?m) by submersed exposure for 24 h. APM surface area of A549 cells was estimated by design-based stereology and transmission electron microscopy. Intracellular particles were visualized and quantified by confocal laser scanning microscopy. Results Particle exposure induced an increase in APM surface area compared to negative control (p < 0.01) at the same surface area concentration of fine and ultrafine particles a finding not observed at low particle concentrations. Ultrafine particle entering was less pronounced than fine particle entering into epithelial cells, however, at the same particle surface area dose, the number of intracellular ultrafine particles was higher than that of fine particles. The number of intracellular particles showed a stronger increase for fine than for ultrafine particles at rising particle concentrations. Conclusion This study demonstrates a particle-induced enlargement of the APM surface area of a pulmonary epithelial cell line, depending on particle surface area dose. Particle uptake by epithelial cells does not seem to be responsible for this effect. We propose that direct interactions between particle surface area and cell membrane cause the enlargement of the APM. PMID:19284624

Brandenberger, Christina; Rothen-Rutishauser, Barbara; Blank, Fabian; Gehr, Peter; Mühlfeld, Christian

2009-01-01

320

Time-resolved characterization of particle associated polycyclic aromatic hydrocarbons using a newly-developed sequential spot sampler with automated extraction and analysis  

NASA Astrophysics Data System (ADS)

A versatile and compact sampling system, the Sequential Spot Sampler (S3) has been developed for pre-concentrated, time-resolved, dry collection of fine and ultrafine particles. Using a temperature-moderated laminar flow water condensation method, ambient particles as small as 6 nm are deposited within a dry, 1-mm diameter spot. Sequential samples are collected on a multiwell plate. Chemical analyses are laboratory-based, but automated. The sample preparation, extraction and chemical analysis steps are all handled through a commercially-available, needle-based autosampler coupled to a liquid chromatography system. This automation is enabled by the small deposition area of the collection. The entire sample is extracted into 50-100 ?L volume of solvent, providing quantifiable samples with small collected air volumes. A pair of S3 units was deployed in Stockton (CA) from November 2011 to February 2012. PM2.5 samples were collected every 12 h, and analyzed for polycyclic aromatic hydrocarbons (PAHs). In parallel, conventional filter samples were collected for 48 h and used to assess the new system's performance. An automated sample preparation and extraction was developed for samples collected using the S3. Collocated data from the two sequential spot samplers were highly correlated for all measured compounds, with a regression slope of 1.1 and r2 = 0.9 for all measured concentrations. S3/filter ratios for the mean concentration of each individual PAH vary between 0.82 and 1.33, with the larger variability observed for the semivolatile components. Ratio for total PAH concentrations was 1.08. Total PAH concentrations showed similar temporal trend as ambient PM2.5 concentrations. Source apportionment analysis estimated a significant contribution of biomass burning to ambient PAH concentrations during winter.

Eiguren-Fernandez, Arantzazu; Lewis, Gregory S.; Spielman, Steven R.; Hering, Susanne V.

2014-10-01

321

Thickening of ultrafine coal-water slurries in a solid-bowl centrifuge  

SciTech Connect

As part of a study being conducted for the Electric Power Research Institute's (EPRI's) Upgraded Coal Interest Group (UCIG) to evaluate ultrafine coal dewatering technologies, testing was carried out to investigate the use of a solid-bowl (high-g) centrifuge for thickening ultrafine coalwater slurries. The objective of this study was to increase the solids concentration to a level suitable for use as a coal-water slurry fuel, while maximizing overall solids recovery. Feed material was collected from the combined discharge (centrate) streams from several screen-bowl centrifuges. These devices are currently being used in a commercial coal cleaning facility to dewater the clean coal product from a froth flotation circuit. Current plant practice is to discharge the centrate to settling ponds. The screen bowl centrate averages 5% solids by weight and contains nearly 60% material finer than 10 {mu}m. The current study examined the effects of operating conditions on centrifuge performance. The test conditions included centrifuge bowl and scroll speeds and volumetric feed rate. In addition to thickening, some cleaning was also achieved, because the finest particles (e.g. < 3 {micro}m), which contained a large percentage of liberated clays, were removed with the bulk of the water. The centrifuge products were analyzed for solids concentration, particle size distribution, and ash content. Size selectivity curves were also used to evaluate centrifuge performance.

Pinkerton, A.P.; Klima, M.S.; Morrison, J.L.; Miller, B.G.

1999-07-01

322

Development of a novel protocol for generating flavivirus reporter particles.  

PubMed

Infection with West Nile virus (WNV), a mosquito-borne flavivirus, is a growing public and animal health concern worldwide. Prevention, diagnosis and treatment strategies for the infection are urgently required. Recently, viral reverse genetic systems have been developed and applied to clinical WNV virology. We developed a protocol for generating reporter virus particles (RVPs) of WNV with the aim of overcoming two major problems associated with conventional protocols, the difficulty in generating RVPs due to the specific skills required for handling RNAs, and the potential for environmental contamination by antibiotic-resistant genes encoded within the genome RNA of the RVPs. By using the proposed protocol, cells were established in which the RVP genome RNA is replicated constitutively and does not encode any antibiotic-resistant genes, and used as the cell supply for RVP genome RNA. Generation of the WNV RVPs requires only the simple transfection of the expression vectors for the viral structural proteins into the cells. Therefore, no RNA handling is required in this protocol. The WNV RVP yield obtained using this protocol was similar that obtained using the conventional protocol. According to these results, the newly developed protocol appears to be a good alternative for the generation of WNV RVPs, particularly for clinical applications. PMID:25116200

Fernández, Igor Velado; Okamoto, Natsumi; Ito, Aki; Fukuda, Miki; Someya, Azusa; Nishino, Yosii; Sasaki, Nobuya; Maeda, Akihiko

2014-11-01

323

Residential indoor and outdoor ultrafine particles in Windsor, Ontario  

NASA Astrophysics Data System (ADS)

UFPs in the 20-100 nm size range were measured for 10 mins every hour for 5 consecutive days in 45 homes of nonsmoking adults in summer 2005 and in 49 homes of asthmatic children in summer and winter 2006. Median hourly outdoor levels across all measurements were 10,800, 12,000 and 6300 cm -3 and median indoor levels were 2700, 3730 and 2580 cm -3 in summer 2005, winter 2006 and summer 2006, respectively. Outdoor levels generally exceeded indoor levels but indoor concentrations were higher around 5-7pm, suggesting a strong influence of cooking. Daily and weekly infiltration factors were estimated for each home using three methods. Weekly infiltration factors ( Finf's) based on a censored indoor/outdoor ratio method varied widely across homes; median Finf's across homes were 0.16 (summer 2005), 0.21 (winter 2006) and 0.26 (summer 2006). Large indoor peaks and low infiltration of ambient PM resulted in the indoor sources generally contributing more than infiltrated ambient UFPs to indoor concentrations. Median estimates of the percentage of indoor-generated contribution to total indoor levels were 58% (summer 2005), 65% (winter 2006) and 69% (summer 2006). The proportion of homes having more than half of their indoor concentrations provided by indoor sources was 66% (summer 2005), 67% (winter 2006) and 79% (summer 2006). Median deposition rates ranged from 0.61-0.79 h -1 across the 3 sampling sessions. Spatial variability was higher for outdoor UFPs than concurrently measured PM 2.5. The median correlations of hourly averaged outdoor UFPs between pairs of homes were moderate in the three sampling sessions (0.56-0.65), but were considerably lower than corresponding PM 2.5 correlations. The wide range of infiltration factors across homes as well as the spatial variability and moderate between- home correlations of outdoor UFPs could cause measurement error in epidemiology studies that use central site UFP measurements as a surrogate for personal exposure to ambient UFPs.

Kearney, J.; Wallace, L.; MacNeill, M.; Xu, X.; VanRyswyk, K.; You, H.; Kulka, R.; Wheeler, A. J.

2011-12-01

324

Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.  

PubMed

Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by solution. We predict that micrometer-sized particles and nanoparticles have the same equilibrium internal structure. The variation of liquid-vapor surface tension with solute concentration is a key factor in determining whether a solution-embedded ice core or vapor-exposed ice cap is the equilibrium structure of the aerosols. In agreement with experiments, we predict that the structure of mixed-phase HNO3-water particles, representative of polar stratospheric clouds, consists of an ice core surrounded by freeze-concentrated solution. The results of this work are important to determine the phase state and internal structure of sea spray ultrafine aerosols and other mixed-phase particles under atmospherically relevant conditions. PMID:24820354

Hudait, Arpa; Molinero, Valeria

2014-06-01

325

Thermal degradation events as health hazards: Particle vs gas phase effects, mechanistic studies with particles  

NASA Astrophysics Data System (ADS)

Exposure to thermal degradation products arising from fire or smoke could be a major concern for manned space missions. Severe acute lung damage has been reported in people after accidental exposure to fumes from plastic materials, and animal studies revealed the extremely high toxicity of freshly generated fumes whereas a decrease in toxicity of aged fumes has been found. This and the fact that toxicity of the freshly generated fumes can be prevented with filters raises the question whether the toxicity may be due to the particulate rather than the gas phase components of the thermodegradation products. Indeed, results from recent studies implicate ultrafine particles (particle diameter in the nm range) as potential severe pulmonary toxicants. We have conducted a number of in vivo (inhalation and instillation studies in rats) and in vitro studies to test the hypothesis that ultrafine particles possess an increased potential to injure the lung compared to larger-sized particles. We used as surrogate particles ultrafine TiO 2 particles (12 and 20 nm diameter). Results in exposed rats showed that the ultrafine TiO 2 particles not only induce a greater acute inflammatory reaction in the lung than larger-sized TiO 2 particles, but can also lead to persistent chronic effects, as indicated by an adverse effect on alveolar macrophage mediated clearance function of particles. Release of mediators from alveolar macrophages during phagocytosis of the ultrafine particles and an increased access of the ultrafine particles to the pulmonary interstitium are likely factors contributing to their pulmonary toxicity. In vitro studies with lung cells (alveolar macrophages) showed, in addition, that ultrafine TiO 2 particles have a greater potential to induce cytokines than larger-sized particles. We conclude from our present studies that ultrafine particles have a significant potential to injure the lung and that their occurrence in thermal degradation events can play a major role in the highly acute toxicity of fumes. Future studies will include adsorption of typical gas phase components (HCl, HF) on surrogate particles to differentiate between gas and particle phase effects and to perform mechanistic studies aimed at introducing therapeutic/preventive measures. These studies will be complemented by a comparison with actual thermal degradation products.

Oberdörster, G.; Ferin, J.; Finkelstein, J.; Soderholm, S.

326

Particles influence allergic responses in mice--role of gender and particle size.  

PubMed

Epidemiological evidence suggesting that exposure to traffic air pollution may enhance sensitization to common allergens in children is increasing, and animal studies support biological plausibility and causality. The effect of air pollution on respiratory symptoms was suggested to be gender dependent. Previous studies showed that allergy-promoting activity of polystyrene particles (PSP) increased with decreasing particle size after footpad injection of mice. The primary aim of this study was to confirm the influence of particle size on the immunoglobulin E (IgE)-promoting capacity of particles in an airway allergy model. A second aim was to examine whether the allergy-promoting capacity of particles was influenced by gender. Female and male mice were intranasally exposed to the allergen ovalbumin (OVA) with or without ultrafine, fine, or coarse PSP modeling the core of ambient air particles. After intranasal booster immunizations with OVA, serum levels of OVA-specific IgE antibodies, and also markers of airway inflammation and cellular responses in the lung-draining mediastinal lymph nodes (MLN), were determined. PSP of all sizes promoted allergic responses, measured as increased serum concentrations of OVA-specific IgE antibodies. Further, PSP produced eosinophilic airway inflammation and elevated MLN cell numbers as well as numerically reducing the percentage of regulatory T cells. Ultrafine PSP produced stronger allergic responses to OVA than fine and coarse PSP. Although PSP enhanced sensitization in both female and male mice, significantly higher IgE levels and numbers of eosinophils were observed in females than males. However, the allergy-promoting effect of PSP was apparently independent of gender. Thus, our data support the notion that ambient air particle pollution may affect development of allergy in both female and male individuals. PMID:24588227

Alberg, Torunn; Hansen, Jitka Stilund; Lovik, Martinus; Nygaard, Unni Cecilie

2014-01-01

327

Synthesis of Ultrafine Nickel-Iron Powder by the Magnesium Reduction in Gas Phase  

NASA Astrophysics Data System (ADS)

Ultra fine metallic powders have an increasing application in magnetic materials, catalysts and chemical and metallic industries. In this research, magnesium-thermic reduction in gas phase was used to synthesize an ultra-fine nickel-iron intermetallic compound. Synthesis of nickel-iron submicron powder by metal chlorides and magnesium vapors was studied. Evaporation rate of the chlorides and magnesium in the range of 800 to 920 degrees Celsius was measured in order to control the composition of the resulting compound. The simultaneous reduction of the chlorides was done in a tubular furnace under argon atmosphere at 920 degrees Celsius. Chemical analysis of the resulting compound and the X ray diffraction analysis identified the formation of Ni3Fe compound. The particle size of the compound was measured 60 to 230 nano-meters by scanning electron microscopy. In addition, the particles were spherical and homogeneous. The product may be used for production of magnetic and catalytic applications.

Tabatabaei, Seyed Yousef; Bateni, Ali; Firoozi, Sadegh

328

New particle formation at a remote continental site: Assessing the contributions of SO2 and organic precursors  

Microsoft Academic Search

Ultrafine aerosols, with diameters less than 10 nm, nucleate from gas phase species. The composition of newly formed ultrafine atmospheric aerosols is not known with certainty; new particles have variously been conjectured to be sulfates, organic compounds, and sulfate\\/organic mixtures. The 1993 Tropospheric OH Photochemistry Experiment at Idaho Hill, Colorado, provided an opportunity to examine the question of which class

James J. Marti; Rodney J. Weber; Peter H. McMurry; Fred Eisele; David Tanner; Anne Jefferson

1997-01-01

329

Methods for Designing Concurrently Strengthened Severely Deformed Age-Hardenable Aluminum Alloys by Ultrafine-Grained and Precipitation Hardenings  

NASA Astrophysics Data System (ADS)

The age-hardenings behavior and precipitate microstructures with high dislocation density and/or ultrafine grains have been studied for 6022Al-Mg-Si and 2091Al-Li-Cu alloys. The high-pressure torsion (HPT) specimen of the former alloy exhibited either suppressed age hardenings or even age softening, unlike in the cases of the undeformed and cold-rolled specimens, at room temperature (RT) to 443 K (170 °C). On the other hand, the HPT specimen of the latter alloy successfully increased the hardness up to >HV290 at 373 K (100 °C), suggesting that concurrent strengthening by ultrafine-grained and precipitation hardenings can be activated if both alloy system and aging temperature are optimally selected. The corresponding transmission electron microscopy (TEM) microstructures attributed such a high level of hardness to the transgranular precipitation of the nanometer-scale particles within ultrafine grains. From the results of in situ small-angle X-ray scattering (SAXS) measurements, methods to maximize the effect of the combined processing of severe plastic deformation (SPD) and the age-hardenings technique are proposed based on the underlying phase transformation mechanisms.

Hirosawa, Shoichi; Hamaoka, Takumi; Horita, Zenji; Lee, Seungwon; Matsuda, Kenji; Terada, Daisuke

2013-08-01

330

Ultrafine-grained Aluminm and Boron Carbide Metal Matrix Composites  

NASA Astrophysics Data System (ADS)

Cryomilling is a processing technique used to generate homogenously distributed boron carbide (B4C) particulate reinforcement within an ultrafine-grained aluminum matrix. The motivation behind characterizing a composite consisting of cryomilled aluminum B4C metal matrix composite is to design and develop a high-strength, lightweight aluminum composite for structural and high strain rate applications. Cryomilled Al 5083 and B4C powders were synthesized into bulk composite by various thermomechanical processing methods to form plate and extruded geometries. The effects of processing method on microstructure and mechanical behavior for the final consolidated composite were investigated. Cryomilling for extended periods of time in liquid nitrogen has shown to increase strength and thermal stability. The effects associated with cryomilling with stearic acid additions (as a process-control agent) on the degassing behavior of Al powders is investigated and results show that the liberation of compounds associated with stearic acid were suppressed in cryomilled Al powders. The effect of thermal expansion mismatch strain on strengthening due to geometrically necessary dislocations resulting from quenching is investigated and found not to occur in bulk cryomilled Al 5083 and B 4C composites. Previous cryomilled Al 5083 and B4C composites have exhibited ultrahigh strength associated with considerable strain-to-failure (>14 pct.) at high strain rates (>103/s) during mechanical testing, but only limited strain-to-failure (˜0.75 pct.) at quasi-static strain rates (10-3/s). The increased strain to failure at high strain rates is attributed to micro-flaw developments, including kinking, extensive axial splitting, and grain growth were observed after high strain rate deformation, and the significance of these mechanisms is considered.

Vogt, Rustin

331

Oxidation of ultrafine (Si) SiC powders  

Microsoft Academic Search

The increasing usage of ultrafine ceramic powders in the fabrication of highly reliable ceramics results in a growing interest in appropriate processing conditions for these powders. During processing the extremely high surface areas might lead to significant absorbtion of oxygen even at low temperatures. But especially in this temperature regime, oxidation data of powders are rarely available; as far as

R. Vaben; D. Stöver

1994-01-01

332

CEC-500-2010-FS-017 Volatility of Ultrafine Particulate  

E-print Network

. Limited research has been done to characterize compressed natural gas mass emissions and practically-volatile and semi-volatile fractions of ultrafine particulate matter emissions from compressed natural gas vehicles compressed natural gas, and emission control technologies that will best protect human health

333

In vivo deposition of ultrafine aerosols in human nasal and oral airways  

SciTech Connect

The extrathoracic airways, including the nasal passage, oral passage, pharynx, and larynx, are the first targets for inhaled particles and provide an important defense for the lung. Understanding the deposition efficiency of the nasal and oral passages is therefore crucial for assessing doses of inhaled particles to the extrathoracic airways and the lung. Significant inter-subject variability in nasal deposition has been shown in recent studies by Rasmussen, T.R. et al, using 2.6 {mu}m particles in 10 human subjects and in our preliminary studies using 0.004-0.15 {mu}m particles in four adult volunteers. No oral deposition was reported in either of these studies. Reasons for the intersubject variations have been frequently attributed to the geometry of the nasal passages. The aims of the present study were to measure in vivo the nasal airway dimensions and the deposition of ultrafine aerosols in both the nasal and oral passages, and to determine the relationship between nasal airway dimensions and aerosol deposition. A statistical procedure incorporated with the diffusion theory was used to model the dimensional features of the nasal airways which may be responsible for the biological variability in particle deposition. In summary, we have correlated deposition of particles in the size range of 0.004 to 0.15 {mu}m with the nasal dimensions of each subject.

Yeh, Hsu-Chi; Swift, D.L. [John Hopkins Univ., Baltimore, MD (United States); Simpson, S.Q. [Univ. of New Mexico, Albuquerque, NM (United States)] [and others

1995-12-01

334

Dynamic deformation and fracture behavior of ultrafine-grained aluminum alloy fabricates by equal-channel angular pressing  

NASA Astrophysics Data System (ADS)

In the present study, ultrafine-grained microstructures of a conventional 5083 aluminum alloy were fabricated by equal-channel angular pressing, and their dynamic deformation and fracture behavior were investigated. Dynamic torsional tests were conducted on four aluminum alloy specimens using a torsional Kolsky bar, and then the test data were analyzed in relation to microstructures, tensile properties, and adiabatic shear-banding behavior. The equal-channel angular-pressed (ECAP) specimens consisted of ultrafine grains and contained a considerable amount of second-phase particles, which were refined and distributed homogeneously in the matrix as the equal-channel angular pressing pass number increased. The dynamic torsional test results indicated that the maximum shear stress increased, while the fracture shear strain remained constant, with increasing equal-channel angular pressing pass number. Observation of the deformed area beneath the dynamically fractured surface showed that a number of voids initiated mainly at second-phase particle/matrix interfaces and that the number of voids increased with increasing pass number. Adiabatic shear bands of 200 to <300 µm in width were formed in the as-extruded and 1-pass ECAP specimens having coarser particles, whereas they were hardly formed in the four-pass and eight-pass ECAP specimens having finer particles. The possibility of adiabatic shear-band formation was explained by concepts of absorbed deformation energy and void initiation.

Kim, Yang Gon; Hwang, Byoungchul; Lee, Sunghak; Kim, Woo Gyeom; Shin, Dong Hyuk

2005-11-01

335

Number Concentration and Size of Particles in Urban Air: Effects on Spirometric Lung Function in Adult Asthmatic Subjects  

Microsoft Academic Search

Daily variations in ambient particulate air pollution are associated with variations in respiratory lung function. It has been suggested that the effects of particulate matter may be due to particles in the ultrafine (0.01-0.1 µm) size range. Because previous studies on ultrafine particles only used self-monitored peak expiratory flow rate (PEFR), we assessed the associations between particle mass and number

Pasi Penttinen; Kirsi Liisa Timonen; Pekka Tiittanen; Aadu Mirme; Juhani Ruuskanen; Juha Pekkanen

2001-01-01

336

Development of a multifunctional particle spectrometer for space radiation imaging  

Microsoft Academic Search

For future exploration of the solar system, the European Space Agency (ESA) is planning missions to Mercury (BepiColombo), the Sun (SolarOrbiter) and to the moons of Jupiter and Saturn. The expected intensity of radiation during such missions is hazardous for the scientific instruments and the satellite. To extend the lifetime of the satellite and its payload a multifunctional particle spectrometer

Erik Maddox; Alex Palacios; Dimitris Lampridis; Stefan Kraft; Alan Owens; Dana Tomuta; Reint Ostendorf

2008-01-01

337

Particle Deposition in Ventilation Ducts: Connectors, Bends and Developing Turbulent Flow  

Microsoft Academic Search

In ventilation ducts the turbulent flow profile is commonly disturbed or not fully developed, and these conditions are likely to influence particle deposition to duct surfaces. Particle deposition rates at eight S-connectors, in two 90° duct bends and in two ducts where the turbulent flow profile was not fully developed were measured in a laboratory duct system with both bare

Mark R. Sippola; William W. Nazaroff

2005-01-01

338

Nanocasting Synthesis of Ultrafine WO3 Nanoparticles for Gas Sensing Applications.  

PubMed

Ultrafine WO3 nanoparticles were synthesized by nanocasting route, using mesoporous SiO2 as a template. BET measurements showed a specific surface area of 700 m 2/gr for synthesized SiO2, while after impregnation and template removal, this area was reduced to 43 m 2/gr for WO3 nanoparticles. HRTEM results showed single crystalline nanoparticles with average particle size of about 5 nm possessing a monoclinic structure, which is the favorite crystal structure for gas sensing applications. Gas sensor was fabricated by deposition of WO3 nanoparticles between electrodes via low frequency AC electrophoretic deposition. Gas sensing measurements showed that this material has a high sensitivity to very low concentrations of NO2 at 250°C and 300°C. PMID:20672126

Kamali Heidari, Elham; Marzbanrad, Ehsan; Zamani, Cyrus; Raissi, Babak

2009-01-01

339

Nanocasting Synthesis of Ultrafine WO3 Nanoparticles for Gas Sensing Applications  

NASA Astrophysics Data System (ADS)

Ultrafine WO3 nanoparticles were synthesized by nanocasting route, using mesoporous SiO2 as a template. BET measurements showed a specific surface area of 700 m2/gr for synthesized SiO2, while after impregnation and template removal, this area was reduced to 43 m2/gr for WO3 nanoparticles. HRTEM results showed single crystalline nanoparticles with average particle size of about 5 nm possessing a monoclinic structure, which is the favorite crystal structure for gas sensing applications. Gas sensor was fabricated by deposition of WO3 nanoparticles between electrodes via low frequency AC electrophoretic deposition. Gas sensing measurements showed that this material has a high sensitivity to very low concentrations of NO2 at 250°C and 300°C.

Kamali Heidari, Elham; Marzbanrad, Ehsan; Zamani, Cyrus; Raissi, Babak

2010-02-01

340

Early developments: Particle physics aspects of cosmic rays  

NASA Astrophysics Data System (ADS)

Cosmic rays is the birthplace of elementary particle physics. The 1936 Nobel prize was shared between Victor Hess and Carl Anderson. Anderson discovered the positron in a cloud chamber. The positron was predicted by Dirac several years earlier. In subsequent cloud chamber investigations Anderson and Neddermeyer saw the muon, which for some time was considered to be a candidate for the Yukawa particle responsible for nuclear binding. Measurements with nuclear emulsions by Lattes, Powell, Occhialini and Muirhead clarified the situation by the discovery of the charged pions in cosmic rays. The cloud chamber continued to be a powerful instrument in cosmic ray studies. Rochester and Butler found V's, which turned out to be shortlived neutral kaons decaying into a pair of charged pions. Also ?'s, ?'s, and ?'s were found in cosmic rays. But after that accelerators and storage rings took over. The unexpected renaissance of cosmic rays started with the search for solar neutrinos and the observation of the supernova 1987A. Cosmic ray neutrino results were best explained by the assumption of neutrino oscillations opening a view beyond the standard model of elementary particles. After 100 years of cosmic ray research we are again at the beginning of a new era, and cosmic rays may contribute to solve the many open questions, like dark matter and dark energy, by providing energies well beyond those of accelerators.

Grupen, Claus

2014-01-01

341

Direct numerical simulation of particle dispersion in a spatially developing turbulent boundary layer  

NASA Astrophysics Data System (ADS)

We performed DNS of particle-laden spatially developing turbulent boundary layer at Re?=1000-3200. We computed the Lagrangian trajectories of millions of fluid points and solid particles with Stokes number St=0.1, 1, and 5, where St=?p/?k, and ?k was computed at z+ at the streamwise location where particles were released. The particles were gradually released from a line source in the viscous sublayer, buffer layer, and log-layer. We computed the time development of particle mean displacement, dispersion, and turbulent diffusivity. Our DNS results of fluid point mean-displacements are in excellent agreement with those of Batchelor's (1964) theory. Also, our DNS results show that in general particle statistics are strongly influenced by particle's Stokes number. Such dependence is mostly caused by the particles tendency to preferentially accumulate in the viscous sublayer as their Stokes number increases. Furthermore, for t/T L < 1 where TL is the Lagrangian integral time scale, the streamwise and wall-normal dispersions are ? t2 for fluid points and ? t3 for solid particles. For 20 < t/TL < 80, the streamwise dispersion of fluid points and particles with St = 0.1 is approximately ? t5/3, while that of particles with St = 1 and 5 is approximately ? t5/2. For all cases studied and for 20 < t/T L < 80, the wall-normal dispersion is approximately ? t.

Ferrante, A.; Dodd, M.

2012-12-01

342

Development of magnetic luminescent core/shell nanocomplex particles with fluorescence using Rhodamine 6G  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? A simple method was developed to synthesize Co-B/SiO{sub 2}/dye/SiO{sub 2} composite particles. ? The magnetic particle shows that highly luminescent and core/shell particles are formed. ? Such core/shell particles can be easily suspended in water. ? The magnetic particles could detect fluorescence for the application of biosensor. -- Abstract: A simple and reproducible method was developed to synthesize a novel class of Co-B/SiO{sub 2}/dye/SiO{sub 2} composite core/shell particles. Using a single cobalt core, Rhodamine 6G of organic dye molecules was entrapped in a silica shell, resulting in core/shell particles of ?200 nm diameter. Analyses using a variety of techniques such as transmission electron microscopy, X-ray photoelectron spectroscopy, vibration sample magnetometry, confocal laser scanning microscopy, and fluorescence intensity demonstrated that dye molecules were trapped inside the core/shell particles. A photoluminescence investigation showed that highly luminescent and photostable core/shell particles were formed. Such core/shell particles can be easily suspended in water. The synthesized magnetic particles could be used to detect fluorescence on glass substrate arrays for bioassay and biosensor applications.

Lee, Hee Uk; Song, Yoon Seok [Department of Chemical and Biological Engineering, Korea University, 5 Ga, Anam-Dong, Sungbuk-Gu, Seoul 136-701 (Korea, Republic of)] [Department of Chemical and Biological Engineering, Korea University, 5 Ga, Anam-Dong, Sungbuk-Gu, Seoul 136-701 (Korea, Republic of); Park, Chulhwan [Department of Chemical Engineering, Kwangwoon University, 447-1 Wolgye-Dong, Nowon-Gu, Seoul 139-701 (Korea, Republic of)] [Department of Chemical Engineering, Kwangwoon University, 447-1 Wolgye-Dong, Nowon-Gu, Seoul 139-701 (Korea, Republic of); Kim, Seung Wook, E-mail: kimsw@korea.ac.kr [Department of Chemical and Biological Engineering, Korea University, 5 Ga, Anam-Dong, Sungbuk-Gu, Seoul 136-701 (Korea, Republic of)

2012-12-15

343

An Investigation of the CSC-MIG Welding Process for Deposition of Conventional, Ultrafine and Nanostructured MMC Coatings  

NASA Astrophysics Data System (ADS)

Welding based coating deposition techniques allow high rates of material deposition and form a permanent metallurgical bond between the coating and the substrate material. Welding based methods can also provide an economic alternative over other industrial coating deposition processes where high initial capital investment and running costs can be restrictive. As with all technological sectors, the need for new and improved machinery and processes to meet industrial needs provides a drive for continued research. The controlled short-circuit MIG (CSC-MIG) welding system is a newly developed welding apparatus built to overcome several shortcomings associated with traditional MIG welding. It allows for greater control of many welding parameters and has reduced heat input during deposition when compared with conventional MIG welding systems. This project was conducted to understand the CSC-MIG welding system as a process and as a hardfacing deposition technique through examination of the microstructural features and transformations of Ni/WC coatings. Several coatings deposited with a Ni/WC electrode wire, with heat input ranging between 10 J/mm and 110 J/mm, were examined. It was found that the detrimental decarburization reactions acting on the WC particles, as seen in thermal spray systems, do not occur when welding with the CSC-MIG. Although the energy input during welding with the CSC-MIG system is significantly lower than for traditional MIG, dissolution of the reinforcing phase is an issue to be contended with and must be minimized through proper selection of welding parameters. Precipitation of a reaction layer around the WC/W2C reinforcing phase was identified as WC; the average thickness of which increased from 3.8 mum to 7.2 mum for the low and high heat input condition, respectively. Precipitation of newly formed WC particles was also observed; their size distribution increased from D50 = 2.4 mum in the low heat input weldment to D50 = 6.75 mum in the high heat input weldment. The hardness of the deposited coatings decreased from 587 HV10 to 410 HV 10 when the energy input was increased from 10.1 J/mm to 108.7 J/mm. Using a pre-placed powder method, as in submerged arc welding, several coatings were embedded with either conventional, ultrafine or nanostructured WC powder. In the analysis of these tests, it was found that the method of embedding the WC particles into the coating had an effect on the overall dissolution of the reinforcing phase. Although the loss of the nanostructure was observed in coatings embedded with the nanostructured WC feedstock, the precipitation of ultrafine WC single crystals is likely to increase the wear resistance compared with conventional sized WC additions. This thesis contains the first journal articles submitted for publication using results from experiments conducted with a CSC-MIG welding system.

Vespa, Patrick

344

On the interactions between particles and turbulence in a fully-developed channel flow in air  

NASA Astrophysics Data System (ADS)

The interactions between small, dense particles and fluid turbulence have been investigated in a downflow, fully-developed channel in air. The particles were selected to respond to some but not all of the scales of turbulent motions. Particle velocities and concentration fields were examined to determine particle response to turbulence. Gas-phase velocities were measured to investigate turbulence modification by particles; particle relaxation time and mass loading were varied. The channel flow was at Reynolds number 13,800. Three classes of narrowly sized spherical beads were used: 50 micron and 90 micron diameter glass beads and 70 micron diameter copper shot. The particles were smaller than the Kolmogorov scale of turbulence; particle relaxation times ranged from 18 ms to 95 ms. Particle mass loadings ranged up to 0.8 yet particle volume fractions remained under 0.02 percent. Particle and gas-phase velocities were measured by LDA, with pedestal amplitude discrimination. Particle concentration fields were determined from computer processed laser flow visualization (these experiments also used 25 micron glass beads and Lycopodium powder). Particle mean velocity profiles were flatter than air velocity profiles. Streamwise particle velocity fluctuation intensities were larger than the corresponding fluid turbulence intensities, while the opposite behavior was observed in the transverse direction. Particle number density distributions furnished evidence of preferential concentration of particles by turbulence, previously observed in the computational studies of Squires and Eaton. Gas-phase mean velocity profiles exhibited no effects of particle loading, with the air mass flow-rate held constant. Turbulence attenuation increased with both particle mass loading and particle relaxation time, with reductions in turbulence kinetic energy of up to 80 percent. Particles at low mass loadings attenuated turbulence more strongly in the transverse than in the streamwise direction, which is attributed to the different turbulence spectra seen by the particle in the two directions. Turbulence attenuation increased with distance from the wall. Estimates of the contribution of particles to the dissipation of turbulence kinetic energy, based on k-epsilon models, showed that smaller relative increases in dissipation in channel flow, compared with those in forced isotropic turbulence, corresponded to larger reductions of turbulence intensity.

Kulick, Johathan D.

345

Code Development of a 3D Finite Element Particle-In-Cell Code with Adaptive Meshing  

Microsoft Academic Search

Summary form only given. Calabazas Creek Research, Inc., in association with U.C. Berkeley (UCB), is developing a fully relativistic, 3D, one-species, particle-in-cell simulation code with adaptive finite element meshing. This initial version will simulate particles in quasi-static fields, which are solved by the finite element methods. In quasi-static PIC analysis, all particles are synchronized in time, and the electric and

Thuc Bui; L. Ives; J. Verbonceur; C. Birdsall

2005-01-01

346

Unraveling the Atomic Structure of Ultrafine Iron Clusters  

PubMed Central

Unraveling the atomic structures of ultrafine iron clusters is critical to understanding their size-dependent catalytic effects and electronic properties. Here, we describe the stable close-packed structure of ultrafine Fe clusters for the first time, thanks to the superior properties of graphene, including the monolayer thickness, chemical inertness, mechanical strength, electrical and thermal conductivity. These clusters prefer to take regular planar shapes with morphology changes by local atomic shuffling, as suggested by the early hypothesis of solid-solid transformation. Our observations differ from observations from earlier experimental study and theoretical model, such as icosahedron, decahedron or cuboctahedron. No interaction was observed between Fe atoms or clusters and pristine graphene. However, preferential carving, as observed by other research groups, can be realized only when Fe clusters are embedded in graphene. The techniques introduced here will be of use in investigations of other clusters or even single atoms or molecules. PMID:23251781

Wang, Hongtao; Li, Kun; Yao, Yingbang; Wang, Qingxiao; Cheng, Yingchun; Schwingenschlögl, Udo; Zhang, Xi Xiang; Yang, Wei

2012-01-01

347

Pearlitic Transformations in an Ultrafine-Grained Hypereutectoid Steel  

NASA Astrophysics Data System (ADS)

Common steels of both hypo- and hypereutectoid compositions form pearlitic or martensitic constituents when cooled from austenite temperature in air or in water. Here, we provide evidence that this is not the case in an ultrafine-grained hypereutectoid steel. In this system, when the grain size was reduced to a scale of 2 to 4 ?m, normal pearlite could not be obtained when the steel was cooled in air; instead, nanometer-sized granular cementite and ferrite were formed in the eutectoid transformation. When the cooling rate was increased by quenching in saltwater, martensite was no longer formed; instead, fine lamellar pearlite was formed. This research indicates that these abnormal phase transformations were related to the rapid diffusion present in the ultrafine-grained steel, which changed the diffusive transformations.

Liu, Yongning; He, Tao; Peng, Guangjin; Lian, Fuliang

2011-08-01

348

Structural properties of ultrafine Ba-hexaferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Crystal structure of ultrafine Ba-hexaferrite (BaFe12O19) nanoparticles was studied using X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption fine structure (XAFS), and Mössbauer spectroscopy (MS), to be compared to the structure of larger nanoparticles and the bulk. The nanoparticles were synthesized with hydrothermal treatment of an appropriate suspension of Ba and Fe hydroxides in the presence of a large excess of OH-. The ultrafine nanoparticles were formed in a discoid shape, ?10 nm wide and only ?3 nm thick, comparable to the size of the hexagonal unit cell in the c-direction. The HRTEM image analysis confirmed the hexaferrite structure, whereas EDXS showed the composition matching the BaFe12O19 formula. XAFS and MS analyses showed considerable disorder of the structure, most probably responsible for the low magnetization.

Makovec, Darko; Primc, Darinka; Šturm, Sašo; Kodre, Alojz; Hanžel, Darko; Drofenik, Miha

2012-12-01

349

Unraveling the Atomic Structure of Ultrafine Iron Clusters  

NASA Astrophysics Data System (ADS)

Unraveling the atomic structures of ultrafine iron clusters is critical to understanding their size-dependent catalytic effects and electronic properties. Here, we describe the stable close-packed structure of ultrafine Fe clusters for the first time, thanks to the superior properties of graphene, including the monolayer thickness, chemical inertness, mechanical strength, electrical and thermal conductivity. These clusters prefer to take regular planar shapes with morphology changes by local atomic shuffling, as suggested by the early hypothesis of solid-solid transformation. Our observations differ from observations from earlier experimental study and theoretical model, such as icosahedron, decahedron or cuboctahedron. No interaction was observed between Fe atoms or clusters and pristine graphene. However, preferential carving, as observed by other research groups, can be realized only when Fe clusters are embedded in graphene. The techniques introduced here will be of use in investigations of other clusters or even single atoms or molecules.

Wang, Hongtao; Li, Kun; Yao, Yingbang; Wang, Qingxiao; Cheng, Yingchun; Schwingenschlögl, Udo; Zhang, Xi Xiang; Yang, Wei

2012-12-01

350

Characterization of ultrafine particulate matter from traditional and improved biomass cookstoves.  

PubMed

Biomass combustion in cookstoves has a substantial impact on human health, affects CO2 levels in the atmosphere, and black carbon (BC) and organic carbon (OC) affect the earth's radiative balance. Various initiatives propose to replace traditional fires with "improved" (nontraditional) cookstoves to offset negative local and global effects. In this laboratory study, we compared the size, composition, and morphology of ultrafine particulate emissions from a "three-stone" traditional fire to those from two improved stove designs (one "rocket", one "gasifier"). Measurement tools included a scanning mobility particle sizer, PTFE and quartz filter samples, and transmission electron microscopy. In the improved stoves, particulate mass (PM) emissions factors were much lower although median particle size was also lower: 35 and 24 nm for the rocket and gasifier, respectively, vs 61 nm for the three-stone fire. Particles from improved stoves formed clearly defined chain agglomerates and independent spheres with little evidence of volatile matter and had a higher proportion of BC to total PM, although overall BC emissions factors were fairly uniform. The 3-fold increase in quantities of sub-30 nm particles from improved cookstoves warrants further consideration by health scientists, with due consideration to the higher combustion efficiencies of improved cookstoves. PMID:23469776

Just, Brian; Rogak, Steven; Kandlikar, Milind

2013-04-01

351

OBSERVATION OF ULTRAFINE CHANNELS OF SOLAR CORONA HEATING  

SciTech Connect

We report the first direct observations of dynamical events originating in the Sun's photosphere and subsequently lighting up the corona. Continuous small-scale, impulsive events have been tracked from their origin in the photosphere on through to their brightening of the local corona. We achieve this by combining high-resolution ground-based data from the 1.6 m aperture New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO), and satellite data from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). The NST imaging observations in helium I 10830 A reveal unexpected complexes of ultrafine, hot magnetic loops seen to be reaching from the photosphere to the base of the corona. Most of these ultrafine loops are characterized by an apparently constant, but surprisingly narrow diameter of about 100 km all along each loop, and the loops originate on the solar surface from intense, compact magnetic field elements. The NST observations detect the signature of upward injections of hot plasma that excite the ultrafine loops from the photosphere to the base of the corona. The ejecta have their individual footpoints in the intergranular lanes between the Sun's ubiquitous, convectively driven granules. In many cases, AIA/SDO detects cospatial and cotemporal brightenings in the overlying, million degree coronal loops in conjunction with the upward injections along the ultrafine loops. Segments of some of the more intense upward injections are seen as rapid blueshifted events in simultaneous H{alpha} blue wing images observed at BBSO. In sum, the observations unambiguously show impulsive coronal heating events from upward energy flows originating from intergranular lanes on the solar surface accompanied by cospatial mass flows.

Ji, Haisheng [Key Laboratory for Dark Matter and Space Science, Purple Mountain Observatory, CAS, Nanjing 210008 (China); Cao, Wenda; Goode, Philip R. [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States)

2012-05-01

352

Taylor particle dispersion during transition to fully developed two-dimensional turbulence  

E-print Network

We report new measurements of single particle dispersion in turbulent two-dimensional (2D) flows. Laboratory experiments in electromagnetically driven and Faraday wave driven turbulence reveal a transition from weakly dispersing superdiffusive regime to strongly dispersing Brownian diffusion as the flow energy is increased in a broad range. The transition to fully developed 2D turbulence is characterized by the topological changes in the fluid particle trajectories and the development of self-similar diffusion. The degree of 2D turbulence development can be quantified by a parameter describing the deviation of single particle dispersion from the Taylor dispersion.

Xia, H; Punzmann, H; Shats, M

2014-01-01

353

PARTICLE DEPOSITION IN A NEARLY DEVELOPED TURBULENT DUCT FLOW WITH ELECTROPHORESIS  

Microsoft Academic Search

This study is concerned with deposition of neutral and charged particles in nearly developed turbulent duct flows. The cases that the duct is vertical or horizontal and when the particles carry Boltzmann, static electrification, as well as saturation charge distributions are analyzed. The mean turbulent flow field is evaluated with the aid of the FLUENT code, using the Reynolds stress

Chunhong He; Goodarz Ahmadi

1999-01-01

354

New developments in particle characterization by laser diffraction: size and shape  

Microsoft Academic Search

Laser diffraction has become a popular technique in many fields for measuring particle size distributions (PSDs). It is not only one of the standard techniques for laboratory measurements but is also gaining importance for on-line process monitoring and process control. This article reports some developments of this technique while recognizing the potential that still exists. In this report both particle

Zhenhua Ma; Henk G Merkus; Jan G. A. E de Smet; Camiel Heffels; Brian Scarlett

2000-01-01

355

Rapid Development of High Ice Particle Concentrations in Small Polar Maritime Cumuliform Clouds  

Microsoft Academic Search

Extremely high ice particle concentrations developed rapidly in the ascending tops of maritime cumulus congestus clouds after drizzle drops had already formed below this level by the collision-coalescence mechanism. In one building cloud with a top temperature no colder than 8°C, the ice particle concentrations increased from 0 to >350 L1 within 9 min. In another cloud with a top

Peter V. Hobbs; Arthur L. Rangno

1990-01-01

356

Development of a particle injection system for impurity transport study in KSTARa)  

NASA Astrophysics Data System (ADS)

A solid particle injection system is developed for KSTAR. The system has a compact size, compatibility with a strong magnetic field and high vacuum environment, and the capability to inject a small amount of solid particles with a narrow injection angle. The target flight-distance of 10 cm has been achieved with a particle loss rate of less than 10%. Solid impurity particles such as tungsten and carbon will be injected by this system at the midplane in KSTAR. The impurity transport feature will be studied with a soft X-ray array, a vacuum ultra-violet diagnostic, and Stand Alone Non-Corona code.

Lee, H. Y.; Hong, Suk-Ho; Hong, Joohwan; Lee, Seung Hun; Jang, Siwon; Jang, Juhyeok; Jeon, Taemin; Park, Jae Sun; Choe, Wonho

2014-11-01

357

Development of a particle injection system for impurity transport study in KSTAR  

SciTech Connect

A solid particle injection system is developed for KSTAR. The system has a compact size, compatibility with a strong magnetic field and high vacuum environment, and the capability to inject a small amount of solid particles with a narrow injection angle. The target flight-distance of 10 cm has been achieved with a particle loss rate of less than 10%. Solid impurity particles such as tungsten and carbon will be injected by this system at the midplane in KSTAR. The impurity transport feature will be studied with a soft X-ray array, a vacuum ultra-violet diagnostic, and Stand Alone Non-Corona code.

Lee, H. Y.; Hong, Joohwan; Lee, Seung Hun; Jang, Siwon; Jang, Juhyeok; Jeon, Taemin; Park, Jae Sun; Choe, Wonho, E-mail: wchoe@kaist.ac.kr [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea and Fusion Plasma Transport Research Center, Daejeon 305-701 (Korea, Republic of); Hong, Suk-Ho [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of)

2014-11-15

358

Development of multiple-layer polymeric particles for targeted and controlled drug delivery  

PubMed Central

The purpose of this work was to develop multilayered particles consisting of a magnetic core and two encompassing shells made up of poly (N-isopropylacrylamide) (PNIPAAm) and poly(d,l-lactide-co-glycolide) (PLGA) for targeted and controlled drug delivery. Transmission electron microscopy confirmed that multilayered particles were obtained with PNIPAAm magnetic nanoparticles embedded within the PLGA shell. Factorial analysis studies also showed that the particle size was inversely proportional to the surfactant concentration and sonication power and directly proportional to the PLGA concentration. Drug-release results demonstrated that these multilayer particles produced an initial burst release and a subsequent sustained release of both bovine serum albumin (BSA) and curcumin loaded into the core and shell of the particle, respectively. BSA release was also affected by changes in temperature. In conclusion, our results indicate that the multilayered magnetic particles could be synthesized and used for targeted and controlled delivery of multiple drugs with different release mechanisms. PMID:19699325

Koppolu, Bhanuprasanth; Rahimi, Maham; Nattama, Sivaniarvindpriya; Wadajkar, Aniket; Nguyen, Kytai Truong

2010-01-01

359

Acute exposure of mice to high-dose ultrafine carbon black decreases susceptibility to pneumococcal pneumonia  

PubMed Central

Background Epidemiological studies suggest that inhalation of carbonaceous particulate matter from biomass combustion increases susceptibility to bacterial pneumonia. In vitro studies report that phagocytosis of carbon black by alveolar macrophages (AM) impairs killing of Streptococcus pneumoniae. We have previously reported high levels of black carbon in AM from biomass smoke-exposed children and adults. We therefore aimed to use a mouse model to test the hypothesis that high levels of carbon loading of AM in vivo increases susceptibility to pneumococcal pneumonia. Methods Female outbred mice were treated with either intranasal phosphate buffered saline (PBS) or ultrafine carbon black (UF-CB in PBS; 500 ?g on day 1 and day 4), and then infected with S. pneumoniae strain D39 on day 5. Survival was assessed over 72 h. The effect of UF-CB on AM carbon loading, airway inflammation, and a urinary marker of pulmonary oxidative stress was assessed in uninfected animals. Results Instillation of UF-CB in mice resulted a pattern of AM carbon loading similar to that of biomass-smoke exposed humans. In uninfected animals, UF-CB treated animals had increased urinary 8-oxodG (P = 0.055), and an increased airway neutrophil differential count (P < 0.01). All PBS-treated mice died within 72 h after infection with S. pneumoniae, whereas morbidity and mortality after infection was reduced in UF-CB treated animals (median survival 48 h vs. 30 h, P < 0.001). At 24 hr post-infection, UF-CB treated mice had lower lung and the blood S. pneumoniae colony forming unit counts, and lower airway levels of keratinocyte-derived chemokine/growth-related oncogene (KC/GRO), and interferon gamma. Conclusion Acute high level loading of AM with ultrafine carbon black particles per se does not increase the susceptibility of mice to pneumococcal infection in vivo. PMID:20958976

2010-01-01

360

Characterization and speciation of depleted uranium in individual soil particles using microanalytical methods  

Microsoft Academic Search

Microanalytical techniques for elemental composition and nuclide-specific analysis have been used to identify the origin and the leachability of depleted uranium particles. The soil particle samples were collected from Kosovo area a few years after the war, the presence of fine particles with depleted uranium as major component was easily identified by EPMA and SIMS. The ultrafine uranium particles were

S. Torok; J Osán; L Vincze; S Kurunczi; G Tamborini; M Betti

2004-01-01

361

Development, characterization, and application of a charged particle microbeam for radiobiological research  

E-print Network

The goal of this work is to develop a charged-particle microbeam for use in radiobiological research at the MIT Laboratory for Accelerator Beam Applications (LABA). The purpose of this device is to precisely explore the ...

Folkert, Michael R. (Michael Ryan), 1975-

2005-01-01

362

Norovirus P particle: a subviral nanoparticle for vaccine development against norovirus, rotavirus and influenza virus  

PubMed Central

Noroviruses (NoVs) are important pathogens causing epidemic acute gastroenteritis that affects millions of people worldwide. The protruding (P) domain of the NoV capsid protein, the surface antigen of NoV, forms a 24-mer subviral particle called the P particle that is an excellent candidate vaccine against NoVs. The P particles are easily produced in Escherichia coli, highly stable and highly immunogenic. Each P domain has three surface loops that can be used for foreign antigen presentation, making the P particles a useful platform for vaccine development against other infectious diseases. This article summarizes the discovery, structure, development and applications of the P particles as a vaccine against NoVs, as well as a vaccine platform against rotavirus, influenza virus and possibly other pathogens in the future. PMID:22734641

Tan, Ming; Jiang, Xi

2012-01-01

363

Densification characteristics of chromia/alumina castables by particle size distribution  

PubMed Central

The quality of the refractories applied on integrated gasification combined cycle should be a key factor that affects both the reliability and the economics of gasifier operation. To enhance the workability of chromia/alumina castables, three types of ultrafine alumina powder were added to improve the workability. Densification behavior of such castables in the presence of ultrafine alumina was assessed through the measurement of parameters like flow value, viscosity, bulk density, apparent porosity, and microstructure evaluation by an SEM study. It's proved that the specific surface area and particle size distribution of ultrafine powders in matrix parts greatly influence the densification behavior of these castables. PMID:22221548

2012-01-01

364

Densification characteristics of chromia/alumina castables by particle size distribution  

NASA Astrophysics Data System (ADS)

The quality of the refractories applied on integrated gasification combined cycle should be a key factor that affects both the reliability and the economics of gasifier operation. To enhance the workability of chromia/alumina castables, three types of ultrafine alumina powder were added to improve the workability. Densification behavior of such castables in the presence of ultrafine alumina was assessed through the measurement of parameters like flow value, viscosity, bulk density, apparent porosity, and microstructure evaluation by an SEM study. It's proved that the specific surface area and particle size distribution of ultrafine powders in matrix parts greatly influence the densification behavior of these castables.

Zhao, Jingming; Kim, Taesuk; Kim, Gichul; Hwang, Kyuhong; Bae, Dongsik

2012-01-01

365

Size and modal analyses of fines and ultrafines from some Apollo 17 samples  

NASA Technical Reports Server (NTRS)

Scanning electron and optical microscopy techniques have been used to determine the grain-size frequency distributions and morphology-based modal analyses of fine and ultrafine fractions of some Apollo 17 regolith samples. There are significant and large differences between the grain-size frequency distributions of the less than 10-micron size fraction of Apollo 17 samples, but there are no clear relations to the local geologic setting from which individual samples have been collected. This may be due to effective lateral mixing of regolith particles in this size range by micrometeoroid impacts. None of the properties of the frequency distributions support the idea of selective transport of any fine grain-size fraction, as has been proposed by other workers. All of the particle types found in the coarser size fractions also occur in the less than 10-micron particles. In the size range from 105 to 10 microns there is a strong tendency for the percentage of regularly shaped glass to increase as the graphic mean grain size of the less than 1-mm size fraction decreases, both probably being controlled by exposure age.

Greene, G. M.; King, D. T., Jr.; Banholzer, G. S., Jr.; King, E. A.

1975-01-01

366

Microstructure and mechanical behavior of ultrafine-grained titanium J. Gubicza1,a  

E-print Network

Microstructure and mechanical behavior of ultrafine-grained titanium J. Gubicza1,a , Zs. Fogarassy1@yahoo.com Keywords: Titanium, Equal Channel Angular Pressing (ECAP), radial forging, drawing, microstructure, mechanical properties. Abstract. Ultrafine-grained titanium was processed by severe plastic deformation (SPD

Gubicza, Jenõ

367

A Compact Water-Based Particle Condensation Monitor  

NASA Astrophysics Data System (ADS)

A water-based, condensation particle counter (ME-WCPC, TSI-3781) has been developed to provide monitoring of particle number concentrations in ambient air and in occupied spaces. This instrument weighs 2.3 kg and has a lower size detection limit near 7 nm. Its internal data logging can date-stamp and store up to two weeks of one-minute data. Reported here is the evaluation of this instrument under field conditions. Comparison is made to three types of butanol-based counters (TSI Models 3010, 3022, 3025) and to bench- scale water based counters (TSI Models 3785 and 3786). Ambient sampling was done in the summer and winter in Riverside, California, and in the winter in Berkeley, California. Residential measurements were made at two homes, including one kitchen. Direct assessment of automotive emissions was made through measurements from the air duct of the Caldecott Freeway Tunnel. At all locations the collocated ME-WCPCs agreed with each other, with the square of the correlation coefficient above 0.97 and slopes near 1. For particle number concentrations below 200,000 cm-3, measurements from the ME-WCPC are within a 10 percent, on average, of those from the butaonol-based TSI-3022, and higher than those from the dilution- corrected TSI-3010, consistent with the differences in the lower particle size limits cutpoints of the instruments (7 nm for the TSI-3022, 10 nm for the TSI-3010). The two ultrafine condensation particle counters, the water- based TSI-3786, and the butanol based TSI-3025, both have lower detection limits of 2.5 nm. These instruments were tightly correlated, with R2 greater than 0.99 with 2% to 9% higher concentrations reported on average from the water-based ultrafine instrument. The one-minute data show consistent diurnal variations, with maxima occurring during the morning, evening hours, and often again near midnight.

Hering, S. V.

2006-12-01

368

On the morphological development of second-phase particles in elastically-stressed solids  

NASA Technical Reports Server (NTRS)

We examine the equilibrium shape and the dynamics of the morphological evolution of a coherent misfitting particle in an elastically anisotropic medium. No a priori assumptions are made on the possible particle morphologies; the particle evolves in a manner consistent with both the diffusion and elastic fields surrounding the particle and the thermodynamics of interfaces in stressed solids. Through these calculations we find the thermodynamically stable equilibrium shape of a misfitting particle. By thermodynamically stable we mean that all the equilibrium conditions, elastic, chemical and interfacial are satisfied simultaneously, in contrast to previous treatments which determined the equilibrium shape by minimizing the sum of the elastic and interfacial energies for certain classes of particle shapes. We find that the equilibrium particle morphologies are not simple geometric shapes, have fourfold symmetry and a continuously varying interfacial curvature with position along the interface. Furthermore, the results show that the times required for a particle to evolve to its equilibrium morphology are likely to be within those which are accessible experimentally. In addition, we develop a general approach for determining the equilibrium shape of a particle in an elastically stressed solid.

Voorhees, P. W.; Mcfadden, G. B.; Johnson, W. C.

1992-01-01

369

Norovirus P Particle, a Novel Platform for Vaccine Development and Antibody Production?  

PubMed Central

The norovirus P particle is an octahedral nanoparticle formed by 24 copies of the protrusion (P) domain of the norovirus capsid protein. This P particle is easily produced in Escherichia coli, extremely stable, and highly immunogenic. There are three surface loops per P domain, making a total of 72 loops per particle, and these are potential sites for foreign antigen presentation for immune enhancement. To prove this concept, a small peptide (His tag, 7 amino acids [aa]) and a large antigen (rotavirus VP8, 159 aa) were inserted into one of the loops. Neither insertion affects P particle formation, while both antigens were presented well on the P particle surface. The immune-enhancement effect of the P particle was demonstrated by significantly increased antibody titers induced by the P particle-presented antigens compared to the titers induced by free antigens. In addition, the measured neutralization antibody titers and levels of protection against rotavirus shedding in mice immunized with the VP8 chimeric P particles were significantly higher than those of mice immunized with the free VP8 antigen. Sera from P particle-VP8 chimera-vaccinated animals also blocked norovirus virus-like particle (VLP) binding to the histo-blood group antigen (HBGA) receptors. From these data, the P particle appears to be an excellent vaccine platform for antigen presentation. The readily available three surface loops and the great capacity for foreign antigen insertion make this platform attractive for wide application in vaccine development and antibody production. The P particle-VP8 chimeras may serve as a dual vaccine against both rotavirus and norovirus. PMID:21068235

Tan, Ming; Huang, Pengwei; Xia, Ming; Fang, Ping-An; Zhong, Weiming; McNeal, Monica; Wei, Chao; Jiang, Wen; Jiang, Xi

2011-01-01

370

About the sizes of elastomer particles in the asphalt concrete binder providing the maximum service life of pavements  

NASA Astrophysics Data System (ADS)

It is noted that the durability of asphalt concrete pavements is determined by the time of the trunk cracks formation in the polymer-containing composites - in the modified by elastomers (e.g., by rubber) bitumenous binder of asphalt. Developed by the authors previously the theory of the cracks propagation in heterosystems [1] has allowed to investigate the problem of the cracks propagation in the rubber-bitumen composite. This investigations show that most effectively to prevente the trunk cracks formation in asphalt concrete can ultrafine rubber particles (150-750 nm) in a bitumenos binder of asphalt.

Kaplan, A. M.; Chekunaev, N. I.

2014-05-01

371

particles  

NASA Astrophysics Data System (ADS)

We explore a facile and nontoxic hydrothermal route for synthesis of a Cu2ZnSnS4 nanocrystalline material by using l-cysteine as the sulfur source and ethylenediaminetetraacetic acid (EDTA) as the complexing agent. The effects of the amount of EDTA, the mole ratio of the three metal ions, and the hydrothermal temperature and time on the phase composition of the obtained product have been systematically investigated. The addition of EDTA and an excessive dose of ZnCl2 in the hydrothermal reaction system favor the generation of kesterite Cu2ZnSnS4. Pure kesterite Cu2ZnSnS4 has been synthesized at 180°C for 12 h from the reaction system containing 2 mmol of EDTA at 2:2:1 of Cu/Zn/Sn. It is confirmed by Raman spectroscopy that those binary and ternary phases are absent in the kesterite Cu2ZnSnS4 product. The kesterite Cu2ZnSnS4 material synthesized by the hydrothermal process consists of flower-like particles with 250 to 400 nm in size. It is revealed that the flower-like particles are assembled from single-crystal Cu2ZnSnS4 nanoflakes with ca. 20 nm in size. The band gap of the Cu2ZnSnS4 nanocrystalline material is estimated to be 1.55 eV. The films fabricated from the hierarchical Cu2ZnSnS4 particles exhibit fast photocurrent responses under intermittent visible-light irradiation, implying that they show potentials for use in solar cells and photocatalysis.

Xia, Yu; Chen, Zhihong; Zhang, Zhengguo; Fang, Xiaoming; Liang, Guozheng

2014-05-01

372

Advanced development of particle beam probe diagnostic system  

NASA Astrophysics Data System (ADS)

This progress report under DOE Grant DE-FG02-85ER3211 covers the period 15 Dec. 1992 through 15 Oct. 1993. The major accomplishments of this period are summarized. The basic TEXT heavy ion beam probe including the primary beam line, the upper secondary beam line with the old 500 keV analyzer, and the lower secondary beam line with the new 2 MeV analyzer is operational, and system shake-down is now beginning. Several subsystems of the complete system design are still under development including secondary beam line sweeps, primary beam detectors, the digital control, and data acquisition system. The lower analyzer entrance aperture and detector plates also have very limited capabilities to make it possible to more rapidly obtain satisfactory initial alignment and calibration conditions. We have performed a variety of high voltage tests that establish the basic efficacy of the 2 MeV analyzer design. We have upgraded the ion optics and added vacuum chambers in our vertical test stand facility to allow us to test the 2 MeV analyzers. We have also constructed a facility for testing ion source characteristics. We analyzed data on primary beam modulation taken during the last run period and confirmed the accuracy of our simulation code. Analysis of magnetic field measurements continued.

Crowley, T. P.; Schoch, P. M.; Connor, K. A.

373

Large Eddy Simulation of Turbulence Modification and Particle Dispersion in a Fully-Developed Pipe Flow  

NASA Astrophysics Data System (ADS)

A LES study of the modification of turbulence in a fully-developed turbulent pipe flow by dispersed heavy particles at Re_? = 360 is presented. A 64 (radial) x 64 (azimuthal) x 128 (axial) grid has been used. An Eulerian-Lagrangian approach has been used for treating the continuous and the dispersed phases respectively. The particle equation of motion included only the drag force. Three different LES models are used in the continuous fluid simulation: (i) A “No-Model” LES (coarse-grid DNS) (ii) Smagorinsky’s model and (iii) Schumann’s model . The motivation behind employing the Schumann’s model is to study the impact of sub-grid-scale fluctuations on the particle motion and their (SGS fluctuations) modulation, in turn, by the particles. The effect of particles on fluid turbulence is investigated by tracking 100000 particles of different diameters. Our studies confirm the preferential concentration of particles in the near wall region. It is observed that the inclusion of two-way coupling reduces the preferential concentration of particles. In addition, it was found that two-way coupling attenuates the fluid turbulence. However, we expect the above trends to differ depending upon the particle diameter, volumetric and mass fractions. The effect of SGS fluctuations on the particle dispersion and turbulence modulation is also being investigated. Other relevant statistics for the continuous and the dispersed phases are collected for the cases of one-way and two-way coupling. These statistics are compared to study the modulation of turbulence by the particles.

Rani, Sarma; Pratap Vanka, Surya

1999-11-01

374

Toxicity of boehmite nanoparticles: impact of the ultrafine fraction and of the agglomerates size on cytotoxicity and pro-inflammatory response.  

PubMed

Boehmite (?-AlOOH) nanoparticles (NPs) are used in a wide range of industrial applications. However, little is known about their potential toxicity. This study aimed at a better understanding of the relationship between the physico-chemical properties of these NPs and their in vitro biological activity. After an extensive physico-chemical characterization, the cytotoxicity, pro-inflammatory response and oxidative stress induced by a bulk industrial powder and its ultrafine fraction were assessed using RAW264.7 macrophages. Although the bulk powder did not trigger a significant biological activity, pro-inflammatory response was highly enhanced with the ultrafine fraction. This observation was confirmed with boehmite NPs synthesized at the laboratory scale, with well-defined and tightly controlled physico-chemical features: toxicity was increased when NPs were dispersed. In conclusion, the agglomerates size of boehmite NPs has a major impact on their toxicity, highlighting the need to study not only raw industrial powders containing NPs but also the ultrafine fractions representative of respirable particles. PMID:24992651

Forest, Valérie; Pailleux, Mélanie; Pourchez, Jérémie; Boudard, Delphine; Tomatis, Maura; Fubini, Bice; Sennour, Mohamed; Hochepied, Jean-François; Grosseau, Philippe; Cottier, Michèle

2014-08-01

375

Development of the Moving Least Squares Smooth Particle Hydrodynamics Approach For Inert/Energetic Material Interaction  

NASA Astrophysics Data System (ADS)

PRIMEX-Warhead Systems (PWS) has developed a smooth particle code based upon a methodology developed by G. Dilts (1999) referred to as MLSPH (Moving Least Squares Smooth Paticles Hydrodynamics). The object is to solve general high rate problems associated with the interaction of energetic and inert materials. Some conservative numerical schemes in cylindrical geometry were developed as well 1D, 2D, and 3D cartesian coding. We use a simple neighbor search technique that limits the computation of searching neighbor particles to one order lower compared to the total CPU time of calculation. PWSuses randomly distributed phantom particles to eliminate certain terms in the numerical growth factor, thus improving the stability of the MLSPH method. In fact, the stability factor can be close to unity. The boundary treatment is also naturally implemented by using this approach. The particle size effect has been minimized through rezoning. PWS developed a new numerical technique of second order accuracy that exactly conserves mass and volume. The rezoning technique provides smoother boundary surface and improves stability by naturally moving apart the particles that are close together. This rezoning method can be used to construct a conservative scheme for volume expansion of particles (mass conservation) that keeps the volume sum of particles equal to the volume enclosed by boundaries, this feature is not satisfied in other SPH schemes. We have also started working on the implementation of a general 3D rezoning technique for SPH. The PWS-MLSPH code is able to deal with material interactions between solid, fluid and gas. Several reaction models are contained in the code to solve problems that involves explosives. In particular the burn process of inert materials contained in an explosive matrix is handled with a 'neighbor ignition' method. That allows an explosive particle to be ignited only by another burning explosive particle that is close enough. We will present a calculation involving the interaction of inert tungsten particles in a TNT matrix. The program will eventually be modified to allow for energy release of metallic particles into the reaction zone (as a function of particle size and coating). The figure below depicts a calculation of 100 micron tungsten in a 60/40 volume ratio.

Yao, Jin; Gunger, Michael

2001-06-01

376

Developments in digital in-line holography enable validated measurement of 3D particle field dynamics.  

SciTech Connect

Digital in-line holography is an optical technique which can be applied to measure the size, three-dimensional position, and three-component velocity of disperse particle fields. This work summarizes recent developments at Sandia National Laboratories focused on improvement in measurement accuracy, experimental validation, and applications to multiphase flows. New routines are presented which reduce the uncertainty in measured position along the optical axis to a fraction of the particle diameter. Furthermore, application to liquid atomization highlights the ability to measure complex, three-dimensional structures. Finally, investigation of particles traveling at near sonic conditions prove accuracy despite significant experimental noise due to shock-waves.

Guildenbecher, Daniel Robert

2013-12-01

377

Preparation of Ultrafine Crystalline TiO2 Powders from Aqueous TiCl4 Solution by Precipitation  

NASA Astrophysics Data System (ADS)

Ultrafine crystalline TiO2 powders were prepared by just heating and stirring aqueous TiOCl2 solution with a Ti+4 concentration of 0.5 mol/l at room temperature to 100°C under one atmosphere. The crystallinity, the phase transformation and the particle shape of ultrafine TiO2 powders obtained by this simple precipitation method were analyzed using an X-ray diffractometer (XRD), transmission electron microscopy (TEM), differential thermal analyzer (DTA), and scanning electron microscopy (SEM). TiO2 crystalline precipitates with a pure rutile phase were formed below 65°C, then TiO2 crystalline precipitates with an anatase phase started forming at temperatures higher than 65°C, which ends with the pure anatase phase at 100°C. The direct formation of TiO2 crystalline precipitates from an aqueous TiOCl2 solution is due to the existence of the OH- ions in distilled water which cause the crystallization of TiOCl2 to TiO2 without hydrolyzation to Ti(OH)4. Conventionally, rutile-phase TiO2 is obtained at much higher temperatures. However, in this study a stable rutile-phase TiO2 was obtained by a simple method at close to room temperature.

Nam, Hee-Dong; Lee, Byung-Ha; Kim, Sun-Jae; Jung, Chung-Hwan; Lee, Ju-Hyeon; Park, Sung

1998-08-01

378

Bulk Nanostructured Materials Obtained by Shock Waves Compaction of Ultrafine Titanium and Aluminum  

NASA Astrophysics Data System (ADS)

Theoretical and experimental Investigations of shock wave consolidation processes of Ti-Al nano sized and ultra-disperse powder compositions are discussed. For theoretical calculations of the shock wave loaded materials were used the hydrodynamic theory and experimental adiabatic of Ti and Al. The normal and tangential stresses in the cylindrical steel tube (containers of Ti-Al reaction mixtures) were estimated using the partial solutions of elasticity theory. The mixtures of ultra-disperse Ti and nano sized (? 50nm) Al powder compositions were consolidated to full or near-full density by explosive-compaction technology. The ammonium nitride based industrial explosives were used for generation of shock waves. To form ultra-fine grained bulk TiAl intermetallics with different compositions, ultra-disperse Ti particles were mixed with nano-crystalline Al. Each reaction mixture was placed in a sealed container and explosively compacted using a normal and cylindrical detonation set-up. Explosive compaction experiments were performed in range of pressure impulse (5-20) GPa. X-ray diffraction (XRD), structural investigations (SEM) and micro-hardness measurements were used to characterize the intermetallics phase composition and mechanical properties. The results of analysis revealing the effects of the compacting conditions and precursor particles sizes, affecting the consolidation and the properties of this new ultra high performance alloys are discussed.

Chikhradze, Nikoloz M.; Politis, Constantin; Chikhradze, Mikheil; Oniashvili, George

379

Investigation of the Co particle size distribution in ensembles produced by reduction from Co oxide  

Microsoft Academic Search

We outline the method for evaluation of the particle size distribution of the magnetic nanoparticles from the hysteresis loop measurements. We apply the method to study the ultrafine Co particles filling the porous silica gel matrix (SiO2). The influence of the technological conditions of the sample preparation onto particle size distribution function is demonstrated.

N. Bagrets; N. Perov; A. Bagrets; A. Lermontov; G. Pankina; P. Chernavskii

2004-01-01

380

Cytotoxicity of ultrafine monodispersed nanoceria on human gastric cancer cells.  

PubMed

The safety and toxicity of CeO2 nanoparticles (nanoceria) are of growing concern due to their potential applications in biological and medical fields based on the radical scavenging and UV-filtering properties. In this paper, the ultrafine monodisperse (2-5 nm) water-insoluble (CeO2-P) and water-soluble nanoceria modified with various functional groups of dextran (CeO2-dextran), polyacrylic acid (CeO2-PAA) and ethylenediamine (CeO2-EDA) on surface were synthesized via alkaline-based precipitation and inverse microemulsion methods. The cell uptaking, oxidative stress and cytotoxicity of these nanoceria on human gastric cancer cell line (BGC-803) were systematically investigated. It is found that the cell uptaking of nanoceria is largely relied on the function groups on its surfaces and followed the order: CeO2-P > CeO2-EDA > CeO2-dextran > CeO2-PAA. Moreover, the oxidative stress of BGC-803 cells is obviously affected by the antioxidant capacity of nanoceria determined by Ce3+/Ce4+ ratio, which eventually causes the cell viability variable once the nanoceria entered into BGC-803 cells. In addition, the cell viability is also closely correlated with the concentration and surface characteristics of nanoceria. The cytotoxicity of nanoceria on BGC-803 cells is largely dependent on its surface functional groups. Our work may provide guidance on the cytotoxicity of ultrafine monodisperse nanoceria for their uses in biological and medical fields. PMID:24804543

Li, Changyan; Zhao, Wenzhi; Liu, Baocang; Xu, Guangran; Liu, Lixia; Lv, Haibo; Shang, Dandan; Yang, Dezhi; Damirin, Aletangaole; Zhang, Jun

2014-07-01

381

Recent developments of coatings for GCFR and HTGCR fuel particles and their performance  

NASA Astrophysics Data System (ADS)

Recent developments in the fabrication and properties of pyrolytic carbon and silicon carbide coatings, suitable for coated nuclear fuel particles, are described. Particularly, these properties have been related to the performance of fuel particles suitable for high temperature gas-cooled reactors and on a rather more tentative basis for gas-cooled fast reactors. Silicon carbide coatings cam withstand appreciable tensile stresses, particularly if the flaw size in the coating surface is minimised. This feature of silicon carbide, in addition to its dimensional stability under fast neutron dose, allows a change in the philosophy of coated particle design, in turn leading to increases in performance. Methods of preparing pure dense silicon carbide in the temperature range 1200-1700 °C are described, together with dense isotropic pyrolytic carbons which can be deposited from butane, propylene or acetylene. The effects of these advances on coated particle design are also discussed.

Ford, L. H.; Hibbert, N. S.; Martin, D. G.

1972-11-01

382

Development of a Simple Sintering Law for Fractal Aggregates Composed of Unequal Sized Primary Particles  

NASA Astrophysics Data System (ADS)

Sintering of silicon nanoparticle chain aggregates composed of unequal sized primary particles are investigated using molecular dynamics (MD) simulations at 1500 K. We consider straight chain aggregates consisting of up to 40 2.5 and 5.4 nm primary particles. The sintering time increases with increase in the total volume of the chain aggregate or with increase in the exposed initial surface area of the chain. A mathematical model was developed to describe the dynamics of sintering of such chain aggregates. The model is a power law modification of the Frenkel sintering equation with the Koch-Friedlander model to include primary particle size dependence. We found that the particle size effect is a local process, and important only at the initial stage of the sintering. Thus, the effect is not significant when the aggregate becomes large. The model is amenable for use in aerosol models that might include sintering effects.

Hawa, Takumi; Zachariah, Michael

2008-03-01

383

Development of an improved method to perform single particle analysis by TIMS for nuclear safeguards.  

PubMed

A method is described that allows measuring the isotopic composition of small uranium oxide particles (less than 1?m in diameter) for nuclear safeguards purposes. In support to the development of reliable tools for the identification of uranium and plutonium signatures in trace amounts of nuclear materials, improvements in scanning electron microscopy (SEM) and thermal ionization mass spectrometry (TIMS) in combination with filament carburization and multiple ion counting (MIC) detection were investigated. The method that has been set up enables the analysis of single particles by a combination of analytical tools, thus yielding morphological, elemental and isotopic information. Hereby individual particles of certified reference materials (CRMs) containing uranium at femtogram levels were analysed. The results showed that the combination of techniques proposed in this work is suitable for the accurate determination of uranium isotope ratios in single particles with improved capabilities for the minor abundant isotopes. PMID:21296200

Kraiem, M; Richter, S; Kühn, H; Aregbe, Y

2011-02-28

384

Particle deposition to forests: An alternative to K-theory  

NASA Astrophysics Data System (ADS)

It has been known for some time that flux-gradient closure schemes (or K-theory), widely used to model the aerosol sized particle turbulent diffusivity, are problematic within canopies. Reported momentum transport in a zero- or counter-mean velocity gradient flow within open trunk spaces of forests is prototypical of the failure of K-theory. To circumvent this problem, a multi-layered and size-resolved second-order closure model is developed using the mean particle turbulent flux budget as a primary closure for the particle turbulent flux instead of K-theory. The proposed model is evaluated against the multi-level size-resolved particle fluxes and particle concentration measurements conducted within and above a tall Scots pine forest situated in Hyytiälä, Southern Finland. Conditions promoting the failure of K-theory for different particle sizes and canopy layers and the characteristics of the particle transport processes within the canopy sub-layer (CSL) are discussed. Using the model, it is shown that K-theory may still be plausible for modeling the particle deposition velocity when the particle size range is smaller than 1 ?m provided the local particle turbulent diffusivity is estimated from the characteristic turbulent relaxation time scale and the vertical velocity variance. Model calculations suggest that the partitioning of particle deposition onto foliage and forest floor appears insensitive to the friction velocity for particles smaller than 100 nm (ultrafine), but decreases with increasing friction velocity for particles larger than 100 nm (accumulation and coarse modes).

Huang, Cheng-Wei; Launiainen, Samuli; Grönholm, Tiia; Katul, Gabriel G.

2014-09-01

385

The morphology of ultrafine atmospheric aerosols: An analysis of inertial deposition, condensation and evaporation, chemical composition, and spatial variation  

NASA Astrophysics Data System (ADS)

A large fraction of the Los Angeles ultrafine atmospheric aerosol (UAA) consists of nanoparticle chain aggregates (NCAs; Xiong and Friedlander, 2001). NCAs are often sized and collected using instruments that rely on inertial transport mechanisms. A new method of interpreting the aerodynamic diameter of NCAs was described. The method can be used to calculate aggregate surface area or volume. A linear relationship between aggregate aerodynamic diameter and primary particle diameter based on published Monte-Carlo drag calculations was derived. The relationship shows that the aggregate aerodynamic diameter is independent of the number of primary particles that compose an aggregate, hence the aggregate mass. The analysis was applied to the collection of NCAs by a low-pressure impactor. Measurements of aggregates collected near a major freeway and at Los Angeles International Airport were made for two aerodynamic cutoff diameter diameters, 50 nm and 75 nm. In both measurements, the aggregate aerodynamic diameters calculated from the primary particle diameter were fairly close to the stage cutoff diameter. The number of primary particles per aggregate varied one order of magnitude for particles depositing on the same stage. The first study of the effect of condensation and evaporation of water on atmospheric aggregate morphology was carried out. Measurements of fractal dimension indicate that the morphology of ultrafine atmospheric aggregates did not change following once cycle of condensation and evaporation at saturation ratio 1.8. It is possible that during condensation, aggregates may not become fully incorporated in water droplets, and this may prevent restructuring. Spatial variation in the morphology of UAA near a major freeway was investigated. UAA with 50 nm electrical mobility diameter was charged and selected with a differential mobility analyzer, and collected using a nanometer aerosol sampler (NAS). The fraction of particles with multiple inclusions measured 90 m from I-405 was significantly greater than the fraction on I-405 (p < 0.001). The increase in the member of particles with multiple inclusions with increasing distance from the freeway suggests that dilution does not prevent particles from colliding and merging. Thus, coagulation may play a role in altering the particle number-size distribution.

Barone, Teresa Louise

386

Experiments measuring particle deposition from fully developed turbulent flow in ventilation ducts  

SciTech Connect

Particle deposition in ventilation ducts influences particle exposures of building occupants and may lead to a variety of indoor air quality concerns. Experiments have been performed in a laboratory to study the effects of particle size and air speed on deposition rates of particles from turbulent air flows in galvanized steel and internally insulated ducts with hydraulic diameters of 15.2 cm. The duct systems were constructed of materials typically found in commercial heating, ventilating and air conditioning (HVAC) systems. In the steel duct system, experiments with nominal particle sizes of 1, 3, 5, 9 and 16 {micro}m were conducted at each of three nominal air speeds: 2.2, 5.3 and 9.0 m/s. In the insulated duct system, deposition rates of particles with nominal sizes of 1, 3, 5, 8 and 13 {micro}m were measured at nominal air speeds of 2.2, 5.3 and 8.8 m/s. Fluorescent techniques were used to directly measure the deposition velocities of monodisperse fluorescent particles to duct surfaces (floor, wall and ceiling) at two straight duct sections where the turbulent flow profile was fully developed. In steel ducts, deposition rates were higher to the duct floor than to the wall, which were, in turn, greater than to the ceiling. In insulated ducts, deposition was nearly the same to the duct floor, wall and ceiling for a given particle size and air speed. Deposition to duct walls and ceilings was greatly enhanced in insulated ducts compared to steel ducts. Deposition velocities to each of the three duct surface orientations in both systems were found to increase with increasing particle size or air velocity over the ranges studied. Deposition rates measured in the current experiments were in general agreement with the limited observations of similar systems by previous researchers.

Sippola, Mark R.; Nazaroff, William W.

2003-08-01

387

Energy Conservation/Waste Reduction in the Processing of Soft (Unfired) Ceramic Particles Via Dynamic Cyclone Classification  

SciTech Connect

The objective of this project was to advance the development of a novel inertial classifier technology to a full-scale industrial product by sequentially evaluating performance of pre-commercial prototypes. The technology, termed a ''Dynamic Cyclone Classifier'' (DCC), utilizes boundary layers on rotating annular disks to effect particle separation with minimal particle-rotor impaction. Although a large (2-ton/hr) DCC was originally envisioned for use within the mining industry, a smaller (kg/hr) sub-10-mm ''Fine Particle Dynamic Cyclone Classifier'' (FPDCC) was subsequently developed as a result of market research that showed higher commercialization potential for classifying ultrafine powders. Modified FPDCC prototypes were iteratively tested and evaluated in the sub-10-mm particle size range using standardized test particles (i.e., ISO Fine test dust). Classification performance tests were assessed by varying device parameters to define the operational envelope of the device to obtain sharp classification cuts, to maximize particle dispersion, to limit particle attrition and to increase production yields. The FPDCC exhibited sub-10-mm performance using both ideal (ISO test dust) and pharmaceutical excipient (calcium carbonate) ultrafine powders. Performance was compared with conventional classification technologies having the ability to process sub-10-mm ultrafine powders, specifically high-efficiency cyclones (HECs) and rotary vane classifiers (RVCs). The FPDCC can generate sharper classification cuts than high-pressure/high efficiency cyclones (HECs), since there is no turbulent particle re-entrainment, while using as much as 95% less energy. Being vaneless, particle impact with high RPM rotor components in the FPDCC is much less severe than in rotary vane classifiers (RVCs), leading to less critical component wear/erosion and concomitantly reducing potential product attrition and contamination. FPDCC energy usage is also less than in RVCs, since rotating vanes require more power to overcome their stronger countercurrent flow. Several large commercial classifier manufacturers have expressed interest in licensing the FPDCC technology for commercialization contingent upon performance validation/verification in the laboratory and at selected Beta test sites. The revised target markets for the FPDCC are pharmaceuticals/neutriceuticals, food products/additives, cosmetics and specialty chemicals. Commercial FPDCC devices will improve product yield, reduce production costs, decrease energy consumption, and minimize process/product waste streams.

Wright, Steve R.

2003-04-15

388

The dynamics of particle disks. III - Dense and spinning particle disks. [development of kinetic theory for planetary rings  

NASA Technical Reports Server (NTRS)

The kinetic theory of planetary rings developed by Araki and Tremaine (1986) and Araki (1988) is extended and refined, with a focus on the implications of finite particle size: (1) nonlocal collisions and (2) finite filling factors. Consideration is given to the derivation of the equations for the local steady state, the low-optical-depth limit, and the steady state at finite filling factors (including the effects of collision inelasticity, spin degrees of freedom, and self-gravity). Numerical results are presented in extensive graphs and characterized in detail. The importance of distinguishing effects (1) and (2) at low optical depths is stressed, and the existence of vertical density profiles with layered structures at high filling factors is demonstrated.

Araki, Suguru

1991-01-01

389
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