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1

Single-ultrafine-particle mass spectrometer development and application  

E-print Network

A single-ultrafine-particle mass spectrometer was constructed and deployed for size-resolved ultrafine aerosol composition measurements during the winter of 2002-2003 in College Station, Texas. Three separate experiments were held between December...

Glagolenko, Stanislav Yurievich

2004-11-15

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

Surgical smoke and ultrafine particles  

PubMed Central

Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine (<100 nm) and accumulation mode particles (< 1 ?m). Epidemiological and toxicological studies have shown that exposure to particulate air pollution is associated with adverse cardiovascular and respiratory health effects. Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc.) was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3) of particles in the diameter range of 10 nm to 1 ?m. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure. PMID:19055750

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

2008-01-01

4

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

PubMed

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

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

2013-05-15

5

Personal exposure to ultrafine particles.  

PubMed

Personal exposure to ultrafine particles (UFP) can occur while people are cooking, driving, smoking, operating small appliances such as hair dryers, or eating out in restaurants. These exposures can often be higher than outdoor concentrations. For 3 years, portable monitors were employed in homes, cars, and restaurants. More than 300 measurement periods in several homes were documented, along with 25?h of driving two cars, and 22 visits to restaurants. Cooking on gas or electric stoves and electric toaster ovens was a major source of UFP, with peak personal exposures often exceeding 100,000 particles/cm³ and estimated emission rates in the neighborhood of 10¹² particles/min. Other common sources of high UFP exposures were cigarettes, a vented gas clothes dryer, an air popcorn popper, candles, an electric mixer, a toaster, a hair dryer, a curling iron, and a steam iron. Relatively low indoor UFP emissions were noted for a fireplace, several space heaters, and a laser printer. Driving resulted in moderate exposures averaging about 30,000 particles/cm³ in each of two cars driven on 17 trips on major highways on the East and West Coasts. Most of the restaurants visited maintained consistently high levels of 50,000-200,000 particles/cm³ for the entire length of the meal. The indoor/outdoor ratios of size-resolved UFP were much lower than for PM?.? or PM??, suggesting that outdoor UFP have difficulty in penetrating a home. This in turn implies that outdoor concentrations of UFP have only a moderate effect on personal exposures if indoor sources are present. A time-weighted scenario suggests that for typical suburban nonsmoker lifestyles, indoor sources provide about 47% and outdoor sources about 36% of total daily UFP exposure and in-vehicle exposures add the remainder (17%). However, the effect of one smoker in the home results in an overwhelming increase in the importance of indoor sources (77% of the total). PMID:20087407

Wallace, Lance; Ott, Wayne

2011-01-01

6

Pulmonary Effects Induced by Ultrafine PTFE Particles  

Microsoft Academic Search

PTFE (polytetrafluoroethylene) fumes consisting of large numbers of ultrafine (uf) particles and low concentrations of gas-phase compounds can cause severe acute lung injury. Our studies were designed to test three hypotheses: (i) uf PTFE fume particles are causally involved in the induction of acute lung injury, (ii) uf PTFE elicit greater pulmonary effects than larger sized PTFE accumulation mode particles,

Carl J. Johnston; Jacob N. Finkelstein; Pamela Mercer; Nancy Corson; Robert Gelein; Günter Oberdörster

2000-01-01

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 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

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 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

9

Magnetic properties of ultrafine iron particles  

Microsoft Academic Search

The magnetic and morphological properties of fine Fe particles have been studied. Ultrafine particles of Fe were prepared using a vapor deposition technique under an argon atmosphere. The argon pressure was varied from 0.5 to 8 Torr during evaporation, and samples with a median diameter in the range 50-200 Å were obtained having a log-normal distribution. The dependence of magnetic

S. Gangopadhyay; G. C. Hadjipanayis; B. Dale; C. M. Sorensen; K. J. Klabunde; V. Papaefthymiou; A. Kostikas

1992-01-01

10

Ultrafine particle-lung interactions: does size matter?  

PubMed

Epidemiological studies continue to indicate associations between exposure to increased concentrations of ambient fine and ultrafine particles and adverse health effects in susceptible individuals. The ultrafine particle fraction in the ambient atmosphere seems to play a specific role. Yet, the dosimetry (including deposition patterns in the respiratory tract and, particularly, the biokinetic fate of ultrafine particles) is not fully understood. In contrast to fine particles, inhaled ultrafine particles seem to follow different routes in the organism. Cardiovascular effects observed in epidemiological studies triggered the discussion on enhanced translocation of ultrafine particles from the respiratory epithelium towards circulation and subsequent target organs, such as heart, liver, and brain, eventually causing adverse effects on cardiac function and blood coagulation, as well as on functions of the central nervous system. Current knowledge on systemic translocation of ultrafine particles in humans and animal models is reviewed. Additionally, an estimate of accumulating particle numbers in secondary target organs during chronic exposure is extrapolated from long-term translocation data obtained from rats. Toxicological studies aim to provide the biological plausibility of health effects of ultrafine particles and to identify cascades of mechanisms that are causal for the gradual transition from the physiological status towards pathophysiologcal alterations and eventually chronic disease. Considering the interaction between insoluble ultrafine particles and biological systems (such as body fluids, proteins, and cells), there still are gaps in the current knowledge on how ultrafine particles may cause adverse reactions. This paper reviews the current concept of interactions between insoluble ultrafine particles and biological systems. PMID:16551218

Kreyling, Wolfgang G; Semmler-Behnke, Manuela; Möller, Winfried

2006-01-01

11

Design and development of an ultrafine particle reflection-time-of-flight mass spectrometer  

E-print Network

aerosol is passed through a differential mobility analyzer to make a monodisperse mixture, which is transmitted through the inlet. The monodisperse particle beam is intercepted by glass slides, and the spot sizes are indicative of the beam shape and width...

Das, Rishiraj

2012-06-07

12

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

EPA Science Inventory

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

13

Study of fine and ultrafine particles for coal cleaning  

SciTech Connect

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

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

1990-04-01

14

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 ...

15

LASER DESORPTION IONIZATION OF ULTRAFINE AEROSOL PARTICLES. (R823980)  

EPA Science Inventory

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

16

Physicochemical characterization of Baizhi particles by ultrafine pulverization  

Microsoft Academic Search

Baizhi, as a medicinal plant, has been demonstrated to be useful for the treatment of aches and pains in China. The physicochemical\\u000a 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

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

2011-01-01

17

Determining Ultrafine Particle Collection Efficiency in a Nanometer Aerosol Sampler  

Microsoft Academic Search

The Nanometer Aerosol Sampler (NAS, Model 3089) manufactured by TSI Incorporated (Minnesota, USA) is commonly used to collect ultrafine particles (UFPs, diameter < 100 nm) for off-line analysis. However, the UFP collection efficiency for this instrument has only been reported for polystyrene latex (PSL) particles at a flow rate of 1 L· min and a voltage of 10 KV. To

Chengjue Li; Shusen Liu; Yifang Zhu

2010-01-01

18

Ultrafine particle emissions from desktop 3D printers  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

19

Assessing Bicyclist and Pedestrian Exposure to Ultrafine Particles: Passive1 Shielding with Noise Barriers2  

E-print Network

to traffic-related air pollutants, including ultrafine23 particles (UFP, particulate matter with aerodynamicAssessing Bicyclist and Pedestrian Exposure to Ultrafine Particles: Passive1 Shielding with Noise exposure to2 ultrafine particles (UFP), particulate matter with aerodynamic diameter less than 0.1 µm

Bertini, Robert L.

20

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

PubMed

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

Janhäll, Sara; Molnar, Peter; Hallquist, Mattias

2012-09-01

21

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...

22

DAILY MORTALITY AND FINE AND ULTRAFINE PARTICLES IN ERFURT, GERMANY  

EPA Science Inventory

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

23

Recycling concrete: An undiscovered source of ultrafine particles  

NASA Astrophysics Data System (ADS)

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

Kumar, Prashant; Morawska, Lidia

2014-06-01

24

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

25

Occupational exposure to ultrafine particles and polycyclic aromatic hydrocarbons from candle emissions.  

E-print Network

??Ultrafine particles (UFPs) are present in the ambient atmosphere and are generated from atmospheric gases, pollution sources, and combustion. Candles emit carbonaceous soot particles similar… (more)

Silver, David J

2005-01-01

26

Filtration Efficiency of Intermediate Ventilation Air Filters on Ultrafine and Submicron Particles.  

E-print Network

??A number of recent epidemiological studies have addressed the association of mortality or morbidity of urban populations with ambient submicron and ultrafine particle concentrations. Evaluating… (more)

Diez Maroto, Maria

2011-01-01

27

Miniaturized ultrafine particle sizer and monitor  

NASA Technical Reports Server (NTRS)

An apparatus for measuring particle size distribution includes a charging device and a precipitator. The charging device includes a corona that generates charged ions in response to a first applied voltage, and a charger body that generates a low energy electrical field in response to a second applied voltage in order to channel the charged ions out of the charging device. The corona tip and the charger body are arranged relative to each other to direct a flow of particles through the low energy electrical field in a direction parallel to a direction in which the charged ions are channeled out of the charging device. The precipitator receives the plurality of particles from the charging device, and includes a disk having a top surface and an opposite bottom surface, wherein a predetermined voltage is applied to the top surface and the bottom surface to precipitate the plurality of particles.

Chen, Da-Ren (Inventor); Qi, Chaolong (Inventor)

2011-01-01

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

Fine and ultrafine particle emissions from microwave popcorn.  

PubMed

This study characterized fine (PM2.5 ) and ultrafine particle (UFP, diameter < 100 nm) emissions from microwave popcorn and analyzed influential factors. Each pre-packed popcorn bag was cooked in a microwave oven enclosed in a stainless steel chamber for 3 min. The number concentration and size distribution of UFPs and PM2.5 mass concentration were measured inside the chamber repeatedly for five different flavors under four increasing power settings using either the foil-lined original package or a brown paper bag. UFPs and PM2.5 generated by microwaving popcorn were 150-560 and 350-800 times higher than the emissions from microwaving water, respectively. About 90% of the total particles emitted were in the ultrafine size range. The emitted PM concentrations varied significantly with flavor. Replacing the foil-lined original package with a brown paper bag significantly reduced the peak concentration by 24-87% for total particle number and 36-70% for PM2.5 . A positive relationship was observed between both UFP number and PM2.5 mass and power setting. The emission rates of microwave popcorn ranged from 1.9 × 10(10) to 8.0 × 10(10) No./min for total particle number and from 134 to 249 ?g/min for PM2.5 . PMID:24106981

Zhang, Q; Avalos, J; Zhu, Y

2014-04-01

30

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

EPA Science Inventory

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

31

Process for making ultra-fine ceramic particles  

DOEpatents

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

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

1995-01-01

32

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

33

Size-Dependent Proinflammatory Effects of Ultrafine Polystyrene Particles: A Role for Surface Area and Oxidative Stress in the Enhanced Activity of Ultrafines  

Microsoft Academic Search

Studies into the effects of ultrafine particles in the lung have shown adverse effects considered to be due in part to the particle size. Air pollution particles (PM10) are associated with exacerbations of respiratory disease and deaths from cardiovascular causes in epidemiological studies and the ultrafine fraction of PM10 has been hypothesized to play an important role. The aim of

D. M. Brown; M. R. Wilson; W. MacNee; V. Stone; K. Donaldson

2001-01-01

34

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

35

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

SciTech Connect

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

Not Available

1992-01-01

36

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

37

Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles  

PubMed Central

Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) throughout their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nanomaterials. Information about safety and potential hazards is urgently needed. Results of older bio-kinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract. The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels. Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species. Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need for basic research on their interactions with subcellular structures. Additional considerations for assessing safety of engineered NSPs include careful selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and also the benefits of possible desirable effects. An interdisciplinary team approach (e.g., toxicology, materials science, medicine, molecular biology, and bioinformatics, to name a few) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment. PMID:16002369

Oberdörster, Günter; Oberdörster, Eva; Oberdörster, Jan

2005-01-01

38

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. ...

39

Photokilling Squamous Carcinoma Cells SCCVII with Ultrafine Particles of Selected Metal Oxides  

Microsoft Academic Search

The ability of ultrafine particles of TiO2, WO3 and iron-doped TiO2 to kill cancer cells in the presence of UV irradiation was investigated. The best photokilling effect on carcinoma cells SCVII cultured in vitro showed iron-doped TiO2 ultrafine particles synthesized by the sol-gel procedure with starting chemicals Ti(IV)-isopropoxide and anhydrous Fe(II)-acetate. It was found that a small particle size and

Siniša Ivankovi?; Marijan Goti?; Mislav Jurin

2003-01-01

40

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

41

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...

42

Immune Potentiation of Ultrafine Dietary Particles in Normal Subjects and Patients with Inflammatory Bowel Disease  

Microsoft Academic Search

Various specific and non-specific environmental factors have been associated with the induction and\\/or exacerbation of disease activity in patients with Crohn's disease and ulcerative colitis. One such factor is the potential role of ingested ultrafine particles. In fact, based on a Western diet, recent data suggest that more than 1012ultrafine particles are ingested per person every day. These microparticles have

J. J Powell; R. S. J Harvey; P Ashwood; R Wolstencroft; M. E Gershwin; R. P. H Thompson

2000-01-01

43

Ultrafine particle removal and generation by portable air cleaners  

NASA Astrophysics Data System (ADS)

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

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

44

The Effect of Ventilation, Age, and Asthmatic Condition on Ultrafine Particle Deposition in Children  

PubMed Central

Ultrafine particles (UFPs) contribute to health risks associated with air pollution, especially respiratory disease in children. Nonetheless, experimental data on UFP deposition in asthmatic children has been minimal. In this study, the effect of ventilation, developing respiratory physiology, and asthmatic condition on the deposition efficiency of ultrafine particles in children was explored. Deposited fractions of UFP (10–200?nm) were determined in 9 asthmatic children, 8 nonasthmatic children, and 5 nonasthmatic adults. Deposition efficiencies in adults served as reference of fully developed respiratory physiologies. A validated deposition model was employed as an auxiliary tool to assess the independent effect of varying ventilation on deposition. Asthmatic conditions were confirmed via pre-and post-bronchodilator spirometry. Subjects were exposed to a hygroscopic aerosol with number geometric mean diameter of 27–31?nm, geometric standard deviation of 1.8–2.0, and concentration of 1.2 × 106 particles cm?3. Exposure was through a silicone mouthpiece. Total deposited fraction (TDF) and normalized deposition rate were 50% and 32% higher in children than in adults. Accounting for tidal volume and age variation, TDF was 21% higher in asthmatic than in non-asthmatic children. The higher health risks of air pollution exposure observed in children and asthmatics might be augmented by their susceptibility to higher dosages of UFP. PMID:22848818

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

2012-01-01

45

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...

46

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

47

Deposition of Ultrafine Particles at Carinal Ridges of the Upper Bronchial Airways  

Microsoft Academic Search

Bifurcations of the upper bronchial airways are primary hot spots for deposition of inhaled particles and noxious gases. Deposition of coarse particles in the carinal ridges results from inertial impaction, and deposition distal to these sites is attributed to secondary flows. Diffusional deposition of ultrafine particles on carinae surfaces is studied here. Similarity solutions for both the flow and concentration

David M. Broday

2004-01-01

48

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

49

Ultrafine particles at three different sampling locations in Taiwan  

NASA Astrophysics Data System (ADS)

Atmospheric ultrafine particles (UPs or PM 0.1) were investigated at the roadside of Syuefu road in Hsinchu city, in the Syueshan highway tunnel in Taipei and in the NTU Experimental Forest in Nantou, Taiwan. A SMPS (TSI 3936) and three MOUDIs (MSP 110) were collocated to determine the number and mass concentrations of the PM 0.1 simultaneously. The filter samples were further analyzed for organic carbon (OC), element carbon (EC), water-soluble ions and trace elements. Taking into account the OC artifact of PM 0.1, good chemical mass closure (ratio of the reconstructed chemical mass to the gravimetrical mass of PMs) was obtained with an unknown percentage of 10.6, 26.2 and 37.2% at the roadside, tunnel and forest, respectively. The unexplained mass was attributed to aerosol water in this study. The artifact at the roadside, tunnel and the forest PM 0.1 mass was found to be as high as 51.6 ± 10.7%, 20.0 ± 5.4% and 85.6 ± 18.4%, respectively. Finally, the effective density of the roadside, tunnel and forest PM 0.1 was calculated based on the results of chemical speciation and found to be 1.45, 1.29 and 1.22 g cm -3, respectively, which was in good agreement with that obtained by using the method of Spencer et al. (2007). Based on these results, it is foreseeable that the number concentration of the SMPS can be converted using the effective density determined by Spencer et al. (2007) for the real time measurement of the PM 0.1 concentration.

Chen, Sheng-Chieh; Tsai, Chuen-Jinn; Chou, Charles C.-K.; Roam, Gwo-Dong; Cheng, Sen-Sung; Wang, Ya-Nan

2010-02-01

50

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

EPA Science Inventory

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

51

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

Microsoft Academic Search

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

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

2004-01-01

52

Airborne Fine and Ultrafine Particles Near the World Trade Center Disaster Site  

Microsoft Academic Search

Documentation of the airborne fine and ultrafine particles produced by the terrorist attack on the World Trade Center (WTC), particularly while fires were burning, was essential for evaluating the risk of adverse health effects in people who live and work in this area. We collected airborne particles for 3 months at a site about 400 m east of the former

Beverly S. Cohen; Maire S. A. Heikkinen; Yair Hazi

2004-01-01

53

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...

54

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

55

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

56

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

57

Size resolved ultrafine particles emission model--a continues size distribution approach.  

PubMed

A new parameterization for size resolved ultrafine particles (UFP) traffic emissions is proposed based on the results of PARTICULATES project (Samaras et al., 2005). It includes the emission factors from the Emission Inventory Guidebook (2006) (total number of particles, #/km/veh), the shape of the corresponding particle size distribution given in PARTICULATES and data for the traffic activity. The output of the model UFPEM (UltraFine Particle Emission Model) is a sum of continuous distributions of ultrafine particles emissions per vehicle type (passenger cars and heavy duty vehicles), fuel (petrol and diesel) and average speed representative for urban, rural and highway driving. The results from the parameterization are compared with measured total number of ultrafine particles and size distributions in a tunnel in Antwerp (Belgium). The measured UFP concentration over the entire campaign shows a close relation to the traffic activity. The modelled concentration is found to be lower than the measured in the campaign. The average emission factor from the measurement is 4.29E+14 #/km/veh whereas the calculated is around 30% lower. A comparison of emission factors with literature is done as well and in overall a good agreement is found. For the size distributions it is found that the measured distributions consist of three modes--Nucleation, Aitken and accumulation and most of the ultrafine particles belong to the Nucleation and the Aitken modes. The modelled Aitken mode (peak around 0.04-0.05 ?m) is found in a good agreement both as amplitude of the peak and the number of particles whereas the modelled Nucleation mode is shifted to smaller diameters and the peak is much lower that the observed. Time scale analysis shows that at 300 m in the tunnel coagulation and deposition are slow and therefore neglected. The UFPEM emission model can be used as a source term in dispersion models. PMID:21641631

Nikolova, Irina; Janssen, Stijn; Vrancken, Karl; Vos, Peter; Mishra, Vinit; Berghmans, Patrick

2011-08-15

58

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

59

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

Microsoft Academic Search

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

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

2009-01-01

60

Indoor air quality for chemical and ultrafine particle contaminants from printers  

Microsoft Academic Search

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

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

2007-01-01

61

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

62

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

SciTech Connect

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

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

2010-07-15

63

Effect of flow characteristics on ultrafine particle emissions from range hoods.  

PubMed

In order to understand the physical mechanisms of the production of nanometer-sized particulate generated from cooking oils, the ventilation of kitchen hoods was studied by determining the particle concentration, particle size distribution, particle dimensions, and hood's flow characteristics under several cooking scenarios. This research varied the temperature of the frying operation on one cooking operation, with three kinds of commercial cooking oils including soybean oil, olive oil, and sunflower oil. The variations of particle concentration and size distributions with the elevated cooking oil temperatures were presented. The particle concentration increases as a function of temperature. For oil temperatures ranging between 180°C and 210°C, a 5°C increase in temperature increased the number concentration of ultrafine particles by 20-50%. The maximum concentration of ultrafine particles was found to be approximately 6 × 10(6) particles per cm(3) at 260°C. Flow visualization techniques and particle distribution measurement were performed for two types of hood designs, a wall-mounted range hood and an island hood, at a suction flow rate of 15 m(3) min(-1). The flow visualization results showed that different configurations of kitchen hoods induce different aerodynamic characteristics. By comparing the results of flow visualizations and nanoparticle measurements, it was found that the areas with large-scale turbulent vortices are more prone to dispersion of ultrafine particle leakage because of the complex interaction between the shear layers and the suction movement that results from turbulent dispersion. We conclude that the evolution of ultrafine particle concentration fluctuations is strongly affected by the location of the hood, which can alter the aerodynamic features. We suggest that there is a correlation between flow characteristics and amount of contaminant leakage. This provides a comprehensive strategy to evaluate the effectiveness of kitchen hoods in capturing cooking oil fumes, which is based on an assessment of the entire hood face exposure instead of on breathing-zone sampling alone. PMID:23479025

Tseng, Li-Ching; Chen, Chih-Chieh

2013-08-01

64

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; Oberdorster, Gunter

2005-01-01

65

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

66

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

Microsoft Academic Search

In June 1996–June 1997 Berner low-pressure impactors were used at an urban and at a rural site in the Helsinki area for sampling ultrafine particles (UFP, PM0.1). Ten sample pairs, each pair measured simultaneously, were collected in the size range of 0.03–15?m of particle aerodynamic diameter. More than 40 chemical components were measured. Surprisingly, the average UFP mass concentration was

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

2001-01-01

67

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

Microsoft Academic Search

The concentration of ultrafine particles (0.01 to greater than 1 ?m) was measured in some rural and urban areas of Sweden and Denmark. The instruments used are handheld real-time condensation particle counters, models CPC 3007 and P-Trak™ 8525, both manufactured by TSI. Field measurements in Sweden were conducted in a few residential and office buildings, while in Denmark the measurement

Uve Matson

2005-01-01

68

¹¹¹Indium-labeled ultrafine carbon particles; a novel aerosol for pulmonary deposition and retention studies.  

PubMed

Continuous environmental or occupational exposure to airborne particulate pollution is believed to be a major hazard for human health. A technique to characterize their deposition and clearance from the lungs is fundamental to understand the underlying mechanisms behind their negative health effects. In this work, we describe a method for production and follow up of ultrafine carbon particles labeled with radioactive ¹¹¹Indium (¹¹¹In). The physicochemical and biological properties of the aerosol are described in terms of particle size and concentration, agglomeration rate, chemical bonding stability, and human lung deposition and retention. Preliminary in vivo data from a healthy human pilot exposure and 1-week follow up of the aerosol is presented. More than 98% of the generated aerosol was labeled with Indium and with particle sizes log normally distributed around 79? nm count median diameter. The aerosol showed good generation reproducibility and chemical stability, about 5% leaching 7 days after generation. During human inhalation, the particles were deposited in the alveolar space, with no central airways involvement. Seven days after exposure, the cumulative activity retention was 95.3%. Activity leaching tests from blood and urine samples confirmed that the observed clearance was explained by unbound activity, suggesting that there was no significant elimination of ultrafine particles. Compared to previously presented methods based on Technegas, ¹¹¹In-labelled ultrafine carbon particles allow for extended follow-up assessments of particulate pollution retention in healthy and diseased lungs. PMID:21391780

Sanchez-Crespo, Alejandro; Klepczynska-Nyström, Anna; Lundin, Anders; Larsson, Britt Marie; Svartengren, Magnus

2011-02-01

69

Development of advanced 3D chip stacking technology with ultra-fine interconnection  

Microsoft Academic Search

The development of 3D chip stacking technology with ultra-fine pitch interconnection initiated in 1999, which is a part of “Ultra High-Density Electronic System Integration” project. The development involves the backend of wafer fabrication process, packaging and testing. The extended study revealed possibilities and advantages of 3D chip stacking structure with ultra-fine interconnection

Kenji Takahashi; Masataka Hoshino; Hitoshi Yonemura; Manabu Tomisaka; Masahiro Sunohara; Michinobu Tanioka; Tomotoshi Sato; Kazumi Kojima; Hiroshi Terao

2001-01-01

70

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

71

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...

72

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

EPA Science Inventory

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

73

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

74

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

75

The influence of a cerium additive on ultrafine diesel particle emissions and kinetics of oxidation  

Microsoft Academic Search

The influence of a cerium additive on the kinetics of oxidation and size distribution of ultrafine diesel particles was studied using a high-temperature oxidation-tandem differential mobility analysis method over the temperature range 300–700?°C. The addition of cerium to the diesel fuel was observed to cause significant changes in number-weighted size distributions, light-off temperature, and kinetics of oxidation. The peak number

Heejung Jung; David B. Kittelson; Michael R. Zachariah

2005-01-01

76

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

Microsoft Academic Search

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

A. Kondo; T. Urabe

1995-01-01

77

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

Microsoft Academic Search

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

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

2010-01-01

78

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

Microsoft Academic Search

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

Chia-Pin Chio; Chung-Min Liao

2008-01-01

79

Mechanism of formation of composite CdS-ZnS ultrafine particles in reverse micelles  

SciTech Connect

The mechanism of formation of composite cadmium sulfide and zinc sulfide ultrafine particles (Cd{sub 1{minus}x}Zn{sub x}S) by simultaneous precipitation of cadmium sulfide and zinc sulfide in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelles has been studied. The particle formation process was followed by the change in UV-visible absorption spectra. The effects of the reactant concentration, the molar ratio of cadmium to zinc ions, and the water content on the particle formation process were investigated. The resultant particles were richer in CdS than the feed composition of the cadmium to zinc ions in the reaction solution. The particle composition was found to be controlled by the solubility of the CdS and ZnS ultrafine particles. The particle coagulation process was analyzed on the basis of a statistical distribution of particles among the reverse micelles. The coagulation rate constant was controlled by the composition and the size of the particles and by the size of the reverse micelles.

Sato, Hiroshi; Hirai, Takayuki; Komasawa, Isao [Osaka Univ., Toyonaka (Japan). Dept. of Chemical Engineering

1995-07-01

80

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

PubMed

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

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

2006-04-01

81

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

82

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

83

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

84

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

NASA Astrophysics Data System (ADS)

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

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

85

Ultrafine particles: exposure and source apportionment in 56 Danish homes.  

PubMed

Particle number (PN) concentrations (10-300 nm in size) were continuously measured over a period of ~45 h in 56 residences of nonsmokers in Copenhagen, Denmark. The highest concentrations were measured when occupants were present and awake (geometric mean, GM: 22.3 × 10(3) cm(-3)), the lowest when the homes were vacant (GM: 6.1 × 10(3) cm(-3)) or the occupants were asleep (GM: 5.1 × 10(3) cm(-3)). Diary entries regarding occupancy and particle related activities were used to identify source events and apportion the daily integrated exposure among sources. Source events clearly resulted in increased PN concentrations and decreased average particle diameter. For a given event, elevated particle concentrations persisted for several hours after the emission of fresh particles ceased. The residential daily integrated PN exposure in the 56 homes ranged between 37 × 10(3) and 6.0 × 10(6) particles per cm(3)·h/day (GM: 3.3 × 10(5) cm(-3)·h/day). On average, ~90% of this exposure occurred outside of the period from midnight to 6 a.m. Source events, especially candle burning, cooking, toasting, and unknown activities, were responsible on average for ~65% of the residential integrated exposure (51% without the unknown activities). Candle burning occurred in half of the homes where, on average, it was responsible for almost 60% of the integrated exposure. PMID:23957328

Bekö, Gabriel; Weschler, Charles J; Wierzbicka, Aneta; Karottki, Dorina Gabriela; Toftum, Jørn; Loft, Steffen; Clausen, Geo

2013-09-17

86

Ultrafine particle removal and ozone generation by in-duct electrostatic precipitators.  

PubMed

Human exposure to airborne ultrafine particles (UFP, < 100 nm) has been shown to have adverse health effects and can be elevated in buildings. In-duct electrostatic precipitator filters (ESP) have been shown to be an effective particulate control device for reducing UFP concentrations (20-100 nm) in buildings, although they have the potential to increase indoor ozone concentrations. This study investigated residential ESP filters to reduce ultrafine particles between 4 to 15 nm and quantified the resulting ozone generation. In-duct ESPs were operated in the central air handling unit of a test house. Results for the two tested ESP brands indicate that removal efficiency of 8 to 14 nm particles was near zero and always less than 10% (± 15%), possibly due to particle generation or low charging efficiency. Adding a media filter downstream of the ESP increased the decay rate for particles in the same size range. Continuous operation of one brand of ESP raised indoor ozone concentrations to 77 ppbv and 20 ppbv for a second brand. Using commercial filters containing activated carbon downstream of the installed ESP reduced the indoor steady-state ozone concentrations between 6% and 39%. PMID:24387032

Poppendieck, Dustin G; Rim, Donghyun; Persily, Andrew K

2014-02-01

87

Atmospheric Condensational Properties of Ultrafine Chain and Fractal Aerosol Particles  

NASA Technical Reports Server (NTRS)

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

Marlow, William H.

1997-01-01

88

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

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

2005-01-01

89

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

PubMed

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 microm 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 microm, and 10 microm. 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. PMID:19583155

Li, Ying; Suriyawong, Achariya; Daukoru, Michael; Zhuang, Ye; Biswas, Pratim

2009-05-01

90

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

SciTech Connect

The research conducted by Textron Defense Systems (TDS) represents a potential new and innovative concept for dispersed coal liquefaction. The technical approach is generation of ultra-fine catalyst particles from supercritical solutions by rapid expansion of either catalyst only, or mixtures of catalyst and coal material in supersaturated solvents. The process of rapid expansion of supercritical fluid solutions was developed at Battelle`s Pacific Northwest Laboratories for the intended purpose of providing a new analytical technique for characterizing supercritical fluids. The concept forming the basis of this research is that ultra-fine particles can be generated from supercritical solutions by rapid expansion of either catalyst or catalyst/coal-material mixtures in supersaturated solvents, such as carbon dioxide or water. The focal point of this technique is the rapid transfer of low vapor pressure solute (i.e., catalyst), dissolved in the supercritical fluid solvent, to the gas phase as the solution is expanded through an orifice. The expansion process is characterized by highly nonequilibrium conditions which cause the solute to undergo extremely rapid supersaturation with respect to the solvent, leading to nucleation and particle growth resulting in nanometer size catalyst particles. A supercritical expansion system was designed and built by TDS at their Haverhill facility.

Not Available

1994-05-01

91

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

92

Surface effects on the magnetic properties of ultrafine cobalt particles  

Microsoft Academic Search

Monodispersed nanoparticles of cobalt have been prepared by an original method using the decomposition under hydrogen of an organometallic precursor in the presence of a stabilizing polymer. Two colloids (Coll-I and Coll-II) have been obtained by changing the organometallic concentration in the polymer. Observation by high-resolution transmission electronic microscopy (HRTEM) showed Co particles well isolated and regularly dispersed in the

M. Respaud; J. M. Broto; H. Rakoto; A. R. Fert; L. Thomas; B. Barbara; M. Verelst; E. Snoeck; P. Lecante; A. Mosset; J. Osuna; T. Ould Ely; C. Amiens; B. Chaudret

1998-01-01

93

Size distribution and emission rate measurement of fine and ultrafine particle from indoor human activities  

NASA Astrophysics Data System (ADS)

Human indoor activities generate airborne particles which contribute to the increase of aerosol concentration levels in the home. The particle size distribution emission rate was measured for 18 different activities (burning candle or incense, cooking, spray use, computer printing and household cleaning). The particle emission rate was calculated from concentration measurements with a DMS500 (CAMBUSTION) in an experimental chamber (2.36 ± 0.05 m 3). The results showed that ultrafine particles are emitted during these activities and the lowest number distribution mode was 6 nm for one of the burning candles. All the cooking activities had similar emissions with a mode between 20 and 40 nm. The measured size distributions were represented in a database by the sum of 1, 2 or 3 lognormal distributions. The measured total emission rate ranged between 0.06 × 10 10 and 13.10 × 10 10 s -1 and the highest emission rate was measured for the self cleaning oven program (pyrolysis).

Géhin, Evelyne; Ramalho, Olivier; Kirchner, Séverine

94

NO decomposition by ultrafine noble metals dispersed on the rare earth phosphate hollow particles  

Microsoft Academic Search

Novel fine polymer particles containing ultrafine Pd, Pt or Rh metal dispersed on the core-shell [core, poly(styrene-co-acrylamide) or poly(styrene-co-acrylic acid); shell, LnPO4(Ln = Ce, Nd, Pr, Sm, La)] type microsphere were prepared by the emulsifier-free emulsion polymerization of styrene with acrylamide or acrylic acid followed by the addition of PdCl2, HPtCl6, or RhCl3 and finally by the addition of a

H. Tamai; T. Ikeya; F. Nishiyama; H. Yasuda; K. Iida; S. Nojima

2000-01-01

95

Surface functionalization of polymer latex particles. III. A convenient method of producing ultrafine poly(methylstyrene) latexes with aldehyde groups on the surface  

Microsoft Academic Search

A convenient method of preparing ultrafine poly(methylstyrene) (PMS) latex particles with aldehyde groups on the surface is developed. PMS latexes in the size range 33-81 nm were prepared via microemulsion polymerization, using cetyltri- methylammonium bromide (CTAB) as surfactant. The surface of the PMS latexes was oxidized in the presence of tert-butyl hydroperoxide catalyzed by copper(II) chloride. As the degree of

Pei Li; Jianjun Xu; Chi Wu

1998-01-01

96

[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

97

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, 1991--December 31, 1991  

SciTech Connect

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

Not Available

1992-01-01

98

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

PubMed

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

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

2012-10-15

99

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

100

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

101

Speciation of size-resolved individual ultrafine particles in Pittsburgh, Pennsylvania  

NASA Astrophysics Data System (ADS)

Approximately 236,000 single particle mass spectra were collected throughout the duration of the Pittsburgh Supersite experiment using the third-generation rapid single particle mass spectrometer (RSMS-3). The instrument was operated semicontinuously for 306 days, sampling particles with aerodynamic diameters in the range of 30-1100 nm and collecting both positive and negative ion spectra, particle size, and time of detection for each particle measured. The entire data set has been fully processed and analyzed. Spectra have been clustered into 20 distinct particle classes on the basis of the distribution of their positive ion mass peaks. Negative ion spectra were classified independently within each positive ion class. Frequency of occurrence versus particle size, month of the year, and wind direction has also been calculated for the full data set, as well as within each class. Results indicate a rich array of multicomponent ultrafine particles composed primarily of carbon and ammonium nitrate. Approximately 54% of all the particles measured fell into the carbonaceous ammonium nitrate (CAN) class. These particles were observed in all size bins and from most wind directions for the entirety of this study. Ubiquitous sources throughout the area, including vehicular emissions and secondary organic aerosol formation, are considered to be responsible for a larger fraction of these particles. In terms of particle number, metal containing aerosol dominated the remainder of the particle classes identified. These particles were rich in K+, Na+, Fe+, and Pb+ and to a lesser extent, Ga+ and Zn+. They tended to be smaller in size and were highly correlated with specific wind directions, facilitating the isolation of specific sources.

Bein, Keith J.; Zhao, Yongjing; Wexler, Anthony S.; Johnston, Murray V.

2005-04-01

102

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

PubMed Central

Cooking emissions show a strong dependence on cooking styles and parameters. Measurements of the average ultrafine particle (UFP) concentration, PM2.5 and black carbon concentrations emitted by cooking activities ranged from 1.34 × 104 to 6.04 × 105 particles/cm3, 10.0 to 230.9 ?g/m3 and 0.1 to 0.8 ?g/m3, respectively. Lower UFP concentrations were observed during boiling, while higher levels were emitted during frying. The highest UFP concentrations were observed when using a gas stove at high temperature with the kitchen exhaust fan turned off. The observed UFP profiles were similar in the kitchen and in another room, with a lag of approximately 10 min. PMID:20617057

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

2010-01-01

103

The possible role of organics in the formation and evolution of ultrafine aircraft particles  

NASA Astrophysics Data System (ADS)

We investigate the potential contribution of organic species emitted by aircraft engines to the formation of ultrafine volatile particles detected in jet wakes. The model employed here includes both acidic and organic aerosols—in their "pure" states and mixed with soot—as well as small ion clusters and electrically charged particles. The microphysical treatment accounts for the effects of charge, within the framework of a multicomponent size-resolved kinetically controlled vapor-aerosol system. Owing to their high proton affinities, water/acid solubility, and/or reactivities with liquid sulfuric acid and other inorganic compounds, certain organic constituents known to be generated by aircraft engines are likely to condense onto ions and charged particles and/or to be taken up by liquid sulfuric acid particles, where these particles are expected to act as efficient reaction sites. The present simulations, which are constrained by in situ measurements, indicate that in the case of very low sulfur emissions, organic species in the exhaust stream can dominate the mass of volatile particles detected at very early times. In the case of fuels with medium to high sulfur contents, the organic emissions may still contribute a significant fraction of the total aerosol mass and alter the composition of the exhaust particles.

Yu, Fangqun; Turco, Richard P.; KäRcher, Bernd

1999-02-01

104

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

EPA Science Inventory

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

105

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, ...

106

Ultrafine Zinc and Nickel, Palladium, Silver Coated Zinc Particles Used for Reductive Dehalogenation of Chlorinated Ethylenes in Aqueous Solution  

Microsoft Academic Search

Zero-valent zinc metal has been employed for the reductive dehalo- genation of chlorinated ethylenes. In order to enhance this envi- ronmental remediation chemistry, ultrafine zinc particles and transition metal additives (coatings) have been employed. Indeed, activated zinc (cryozinc) significantly enhanced the reduction\\/de- halogenation process, especially in the presence of nickel and pal- ladium coatings. These reagents were able to achieve

Weifeng Li; Kenneth J. Klabunde

107

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

PubMed Central

High ambient ultrafine particle (UFP) concentrations may play an important role in the adverse health effects associated with living near busy roadways. However, UFP size distributions change rapidly as vehicle emissions dilute and age. These size changes can influence UFP lung deposition rates and dose because deposition in the respiratory system is a strong function of particle size. Few studies to date have measured and characterized changes in near-road UFP size distributions in real-time, thus missing transient variations in size distribution due to short-term fluctuations in wind speed, direction, or particle dynamics. In this study we measured important wind direction effects on near-freeway UFP size distributions and gradients using a mobile platform with 5-s time resolution. Compared to more commonly measured perpendicular (downwind) conditions, parallel wind conditions appeared to promote formation of broader and larger size distributions of roughly one-half the particle concentration. Particles during more parallel wind conditions also changed less in size with downwind distance and the fraction of lung-deposited particle number was calculated to be 15% lower than for downwind conditions, giving a combined decrease of about 60%. In addition, a multivariate analysis of several variables found meteorology, particularly wind direction and temperature, to be important in predicting UFP concentrations within 150 m of a freeway (R2 = 0.46, p = 0.014). PMID:24415904

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

2013-01-01

108

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

109

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

110

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

PubMed

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

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

2014-05-01

111

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

112

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

113

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

114

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

115

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

116

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

PubMed

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

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

2004-12-01

117

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

NASA Astrophysics Data System (ADS)

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

Marra, J.

2011-07-01

118

The formation and growth of ultrafine particles in two contrasting environments: a case study  

NASA Astrophysics Data System (ADS)

Formation of ultrafine particles and their subsequent growth have been examined during new particle formation (NPF) events in two contrasting environments under varying ambient conditions, one for a tropical semi-urban coastal station, Trivandrum, and the other for a high-altitude free-tropospheric Himalayan location, Hanle. At Trivandrum, NPF bursts took place in the late evening/night hours, whereas at Hanle the burst was a daytime event. During the nucleation period, the total number concentration reached levels as high as ~ 15 900 cm-3 at Trivandrum, whereas at Hanle, the total number concentration was ~ 2700 cm-3, indicating the abundant availability of precursors at Trivandrum and the pristine nature of Hanle. A sharp decrease was associated with NPF for the geometric mean diameter of the size distribution, and a large increase in the concentration of the particles in the nucleation regime (Dp < 25 nm). Once formed, these (secondary) aerosols grew from nucleation (diameter Dp < 25 nm) to Aitken (25 ? Dp ? 100 nm) regime and beyond, to the accumulation size regimes (100 ? Dp ? 1000 nm), with varying growth rates (GR) for the different size regimes at both the locations. A more rapid growth ~ 50 nm h-1 was observed at Trivandrum, in contrast to Hanle where the growth rate ranged from 0.1 to 20 nm h-1 for the transformation from the nucleation to accumulation - a size regime that can potentially act as cloud condensation nuclei (CCN). The faster coagulation led to lifetimes of < 1 h for nucleation mode particles.

Kompalli, Sobhan Kumar; Babu, S. Suresh; Krishna Moorthy, K.; Gogoi, Mukunda M.; Nair, Vijayakumar S.; Chaubey, Jai Prakash

2014-07-01

119

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

120

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

NASA Astrophysics Data System (ADS)

Concentrations of ultrafine (<0.1 ?m) particles (UFPs) and PM 2.5 (<2.5 ?m) were measured whilst commuting along a similar route by train, bus, ferry and automobile in Sydney, Australia. One trip on each transport mode was undertaken during both morning and evening peak hours throughout a working week, for a total of 40 trips. Analyses comprised one-way ANOVA to compare overall (i.e. all trips combined) geometric mean concentrations of both particle fractions measured across transport modes, and assessment of both the correlation between wind speed and individual trip means of UFPs and PM 2.5, and the correlation between the two particle fractions. Overall geometric mean concentrations of UFPs and PM 2.5 ranged from 2.8 (train) to 8.4 (bus) × 10 4 particles cm -3 and 22.6 (automobile) to 29.6 (bus) ?g m -3, respectively, and a statistically significant difference ( p < 0.001) between modes was found for both particle fractions. Individual trip geometric mean concentrations were between 9.7 × 10 3 (train) and 2.2 × 10 5 (bus) particles cm -3 and 9.5 (train) to 78.7 (train) ?g m -3. Estimated commuter exposures were variable, and the highest return trip mean PM 2.5 exposure occurred in the ferry mode, whilst the highest UFP exposure occurred during bus trips. The correlation between fractions was generally poor, and in keeping with the duality of particle mass and number emissions in vehicle-dominated urban areas. Wind speed was negatively correlated with, and a generally poor determinant of, UFP and PM 2.5 concentrations, suggesting a more significant role for other factors in determining commuter exposure.

Knibbs, Luke D.; de Dear, Richard J.

2010-08-01

121

Impact of superplasticizer concentration and of ultra-fine particles on the rheological behaviour of dense mortar suspensions  

SciTech Connect

This work aims at investigating the impact of the addition of superplasticizer and of ultra-fine particles, namely of silica fume and of precipitated titania, on the rheological behaviour of water-lean mortar pastes. The pastes are characterised in terms of their spread, their flowing behaviour and by means of performing a shear test, giving access to viscosity/shear gradient correlations. Adding superplasticizer is shown to shift the onset of shear thickening of the referring pastes to higher shear rates and to attenuate its otherwise rapid evolution, possibly by means of favouring steric particle-particle interactions. The workability of these mortars, which is characterised in terms of spread values and draining, is also improved. For the case of fly ash based mortars, adding ultra-fine particles is another way of (slightly) 'retarding' shear thickening and of attenuating its evolution, possibly because of resulting in - on the average - lower hydrodynamic forces and reduced attractive Van der Waals interactions between particles. However, at the same time these mortars are characterised by a worsening in workability which is attributed to the huge amount of surface area provided by the ultra-fines.

Artelt, C. [Lafarge, Centre de Recherche, 95 rue Montmurier, F-38291 St Quentin Fallavier (France)], E-mail: christian.artelt@lafarge.com; Garcia, E. [Lafarge Granulats, 13 rue Jean-Pierre Timbaud, F-92454 Issy les Moulineaux (France)

2008-05-15

122

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

123

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...

124

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

NASA Astrophysics Data System (ADS)

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

Pryor, S. C.; Crippa, P.

2013-12-01

125

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

PubMed

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

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

2011-12-01

126

Combustion of PTFE: The Effects of Gravity and Pigmentation on Ultrafine Particle Generation  

NASA Technical Reports Server (NTRS)

Ultrafine particles generated during polymer thermodegradation are a major health hazard, owing to their unique pathway of processing in the lung. This hazard in manned spacecraft is poorly understood, because the particulate products of polymer thermodegradation are generated under low gravity conditions. Particulate generated from the degradation of PolyTetraFluoroEthylene (PTFE), insulation coating for 20 AWG copper wire (representative of spacecraft application) under intense ohmic heating were studied in terrestrial gravity and microgravity. Microgravity tests were done in a 1.2-second drop tower at the Colorado School of Mines (CSM). Thermophoretic sampling was used for particulate collection. Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) were used to examine the smoke particulates. Image software was used to calculate particle size distribution. In addition to gravity, the color of PTFE insulation has an overwhelming effect on size, shape and morphology of the particulate. Nanometer-sized primary particles were found in all cases, and aggregation and size distribution was dependent on both color and gravity; higher aggregation occurred in low gravity. Particulates from white, black, red and yellow colored PTFE insulations were studied. Elemental analysis of the particulates shows the presence of inorganic pigments.

McKinnon, J. Thomas; Srivastava, Rajiv; Todd, Paul

1997-01-01

127

London penetration depth determination from ultrafine particles of YBa 2Cu 3O 7  

NASA Astrophysics Data System (ADS)

The London penetration depth is determined in disoriented ultrafine particles of YBa 2Cu 3O 7 by the Schoenberg method. Fine particles are prepared by nebulisation of a nitrate solution followed by fast calcination and appropriate annealing in oxygen. The Meissner effect onset at Tc=91.5±0.5 K is sharp and assesses the stoichiometry of our samples. The ultramicrotome cut particles observed using SEM and TEM microscopy are hollow spheres of mean external diameter 1.4 ?m and mean thickness 65 nm. Further evidence of this topology is given from TEM observations on ultramicrotome cut spheres. The envelope of the sphere is observed to be paved by parallelepipedic-like crystallites. The Meissner fraction in our material varies from 0.5% to 2.2% and is found to increase with increasing size of the crystallites. In order to interpret our magnetic data we use a model which relates the magnitude of the Meissner effect with the simultaneous anisotropy of the geometry of the crystallites and the intrinsic anisotropy of the London penetration depth. The value of the anisotropic London penetration depth corresponding to currents flowing along the a or b directions, ?ab=220±30 nm is then determined from the extrapolated value of the Meissner effect at 0 K.

Stroumbos, H.; Laroui, A.; Monod, P.; Decamps, B.; Dubois, J. P.; Odier, P.

1990-05-01

128

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

NASA Astrophysics Data System (ADS)

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

Chio, Chia-Pin; Liao, Chung-Min

129

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

PubMed

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

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

2013-06-14

130

Composition of fine and ultrafine particles and source identification by stable isotope ratios  

NASA Astrophysics Data System (ADS)

Fine (da < 2.1 ?m) and ultra-fine (da < 0.1?m) atmosphere particulate samples collected from two sites in the United States were analyzed for elemental compositions by Instrumental, Neutron Activation Analysis (INAA) at Massachusetts Institute of Technology. The eastern site samples were collected at the Great Smoky Mountain National Park from July 15 to August 25, 1995. The western site samples were collected from a rooftop in Pasadena, California over one winter month in January/February, 1996. Elemental concentrations determined by INAA for the eastern site samples were compared with results from samples (da < 2.4 ?m) collected concurrently but analyzed by other techniques. The results showed consistency between different analytical techniques. Factor Analysis (FA) and Absolute Factor Score-Multiple Linear Regression (AFS-MLR) methods were used to identify sources and their contributions to fine particulate samples at the eastern site. The results showed that the crustal contribution to fine aerosol mass was significant around July 24-26, 1995, and the coal combustion contribution peaked around August 14-18, 1995. The average contribution from crustal sources to the fine particulate mass was 7 +/- 3% for the 2.1 ?m samples and 11 +/- 4% for the 2.4 ?m samples. The mass difference may be due to the different maximum size of the particles. The average contribution from combustion sources was 77 +/- 4% for the 2.1 ?m samples and 90 +/- 6% for the 2.4 ?m samples. Elemental patterns were used to identify sources of ultra-fine particles. Motor vehicle emissions might be the cause of the increase in the ultra-fine particle concentration of Al and Fe at the western site. Variations in stable isotope ratios of 130Ba/138 Ba, 121Sb/123Sb, 84Sr/ 86Sr and 79Br/81Br were investigated using INAA. This technique was applied to fine particulate samples with sources identified by FA. The results showed that the 130Ba/ 138Ba ratio of the dust sample was 0.00151 +/- 0.00008, and the ratio was 0.00109 +/- 0.00003 for the combustion sample. This suggests that the 130Ba/138Ba ratio can be used to separate contributions from soil and combustion sources even if they have similar chemical compositions. Crustal material may have a lower 121Sb/ 123Sb ratio than the combustion source of fine particles. The 84Sr/86Sr and 79Br/81Br ratios also showed differences between these samples, but the differences were not greater than the statistical uncertainty of the measurements. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

Gone, Jec-Kong

131

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

132

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

133

Assessment of ultrafine particles in Portuguese preschools: levels and exposure doses.  

PubMed

The aim of this work was to assess ultrafine particles (UFP) number concentrations in different microenvironments of Portuguese preschools and to estimate the respective exposure doses of UFP for 3-5-year-old children (in comparison with adults). UFP were sampled both indoors and outdoors in two urban (US1, US2) and one rural (RS1) preschool located in north of Portugal for 31 days. Total levels of indoor UFP were significantly higher at the urban preschools (mean of 1.82 × 10(4) and 1.32 × 10(4)  particles/cm(3) at US1 an US2, respectively) than at the rural one (1.15 × 10(4)  particles/cm(3) ). Canteens were the indoor microenvironment with the highest UFP (mean of 5.17 × 10(4) , 3.28 × 10(4) , and 4.09 × 10(4)  particles/cm(3) at US1, US2, and RS1), whereas the lowest concentrations were observed in classrooms (9.31 × 10(3) , 11.3 × 10(3) , and 7.14 × 10(3)  particles/cm(3) at US1, US2, and RS1). Mean indoor/outdoor ratios (I/O) of UFP at three preschools were lower than 1 (0.54-0.93), indicating that outdoor emissions significantly contributed to UFP indoors. Significant correlations were obtained between temperature, wind speed, relative humidity, solar radiation, and ambient UFP number concentrations. The estimated exposure doses were higher in children attending urban preschools; 3-5-year-old children were exposed to 4-6 times higher UFP doses than adults with similar daily schedules. PMID:24689947

Fonseca, J; Slezakova, K; Morais, S; Pereira, M C

2014-12-01

134

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

135

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

136

Quinones and aromatic chemical compounds in particulate matter induce mitochondrial dysfunction: implications for ultrafine particle toxicity.  

PubMed

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 (Delta-Psi 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 Delta-Psi 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 Delta-Psi 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 Delta-Psi 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

2004-10-01

137

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

NASA Astrophysics Data System (ADS)

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

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

138

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

139

The influence of a cerium additive on ultrafine diesel particle emissions and kinetics of oxidation  

SciTech Connect

The influence of a cerium additive on the kinetics of oxidation and size distribution of ultrafine diesel particles was studied using a high-temperature oxidation-tandem differential mobility analysis method over the temperature range 300-700|{sup o}C. The addition of cerium to the diesel fuel was observed to cause significant changes in number-weighted size distributions, light-off temperature, and kinetics of oxidation. The peak number concentration in the accumulation mode decreased 50 and 65%, respectively, for 25 and 100 ppm dosing levels under 1400 rpm and 75% engine load. The light-off temperature was reduced by 250 and 300|{sup o}C, respectively, for 25 and 100 ppm dosing levels. The oxidation rate increased significantly (x20) with the addition of cerium to the fuel; however, the rate was relatively insensitive to dosing level. The activation energy for cerium-dosed oxidation was, within experimental error, equivalent to that for undosed fuel (E{sub a}=100-110 kJmol{sup -1}). From a phenomenological kinetic rate perspective, the increase in oxidation rate was attributed solely to an increase in the preexponential factor. These results suggested that diesel particles using regular, undosed diesel fuels were already metal-catalyzed to some extent, most likely from metals in the lube oil. The addition of cerium likely increased the number of catalytic sites but had no effect on the overall activation energy due to the presence of other metals in the diesel particulate matter coming from lube oil. The characteristics of cerium-laden diesel particles were also investigated. Two principal types of aggregates were found using transmission electron microscopy and energy-dispersive spectrometry analysis. The first was composed mainly of agglomerates of carbonaceous spherules and a few, considerably smaller cerium oxide nanoparticles. The second consisted of metallic aggregates composed mainly of cerium oxide nanoparticles and some carbon.

Jung, Heejung; Kittelson, David B.; Zachariah, Michael R. [Departments of Mechanical Engineering and Chemistry, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455 (United States)

2005-08-01

140

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

141

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

PubMed

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

Buonanno, G; Stabile, L; Morawska, L

2014-01-15

142

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

143

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

144

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

PubMed Central

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

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

2013-01-01

145

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, which contributes 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 Aitken-mode Particle burst Events (APEs). These measurements suggest that APEs were associated with the arrival at the site of anthropogenic pollution plumes around noon or in the early afternoon. Number concentrations of ultrafine (4 to 30 nm diameter) particles typically exceeded 10 000 cm-3 during APEs, and these elevated concentrations coincided with increased SO2 and monoterpene concentrations, and led to a factor of two increase in CCN concentrations at 0.5% supersaturation. The APEs 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 by condensation of organic and inorganic vapors. Comparisons with aerosol size distribution measurements showed that simulations using the activation nucleation parameterization reasonably captured aerosol number concentrations and size distribution during APEs, as well as ground level CCN concentrations. Results suggest that sulfuric acid from anthropogenic SO2 triggers APEs, and that the condensation of monoterpene oxidation products onto freshly nucleated particles drives their growth. The simulated growth rate of 3.4 nm h-1 for small particles (4-30 nm in diameter) was comparable to the measured average value of 2.3 nm h-1. Model results also suggest that the presence of APEs tends to modify the composition of sub-100 nm diameter particles, leading to generally higher absolute mass concentrations of sulfate as well as organic aerosols with a higher sulfate content. 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 to 65% 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.; Turnipseed, A.; Winkler, P.; de Foy, B.

2014-03-01

146

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

NASA Astrophysics Data System (ADS)

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

Sambaer, Wannes; Zatloukal, Martin; Kimmer, Dusan

2013-04-01

147

The effects of roadside structures on the transport and dispersion of ultrafine particles from highways  

NASA Astrophysics Data System (ADS)

Understanding local-scale transport and dispersion of pollutants emitted from traffic sources is important for urban planning and air quality assessments. Predicting pollutant concentration patterns in complex environments depends on accurate representations of local features (e.g., noise barriers, trees, buildings) affecting near-field air flows. This study examined the effects of roadside barriers on the flow patterns and dispersion of pollutants from a high-traffic highway in Raleigh, North Carolina, USA. The effects of the structures were analyzed using the Quick Urban & Industrial Complex (QUIC) model, an empirically based diagnostic tool which simulates fine-scale wind field and dispersion patterns around obstacles. Model simulations were compared with the spatial distributions of ultrafine particles (UFP) from vehicular emissions measured using a passenger van equipped with a Differential Mobility Analyzer/Condensation Particle Counter. The field site allowed for an evaluation of pollutant concentrations in open terrain, with a noise barrier present near the road, and with a noise barrier and vegetation present near the road. Results indicated that air pollutant concentrations near the road were generally higher in open terrain situations with no barriers present; however, concentrations for this case decreased faster with distance than when roadside barriers were present. The presence of a noise barrier and vegetation resulted in the lowest downwind pollutant concentrations, indicating that the plume under this condition was relatively uniform and vertically well-mixed. Comparison of the QUIC model with the mobile UFP measurements indicated that QUIC reasonably represented pollutant transport and dispersion for each of the study configurations.

Bowker, George E.; Baldauf, Richard; Isakov, Vlad; Khlystov, Andrey; Petersen, William

148

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

149

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; Oberdorster, Gunter

2006-01-01

150

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

PubMed Central

Background Clara cell protein (CC16), the main secretory product of bronchiolar Clara cells, plays an important protective role in the respiratory tract against oxidative stress and inflammation. The purpose of the study was to investigate the role of elemental carbon ultrafine particles (EC-UFP)-induced oxidative stress on Clara cells and CC16 in a mouse model of allergic lung inflammation. Methods Ovalbumin (OVA)-sensitized mice were exposed to EC-UFP (507 ?g/m3 for 24 h) or filtered air immediately prior to allergen challenge and systemically treated with N-acetylcysteine (NAC) or vehicle prior and during EC-UFP inhalation. CC16 was measured up to one week after allergen challenge in bronchoalveolar lavage fluid (BALF) and in serum. The relative expression of CC16 and TNF-? mRNA were measured in lung homogenates. A morphometrical analysis of mucus hypersecretion and electron microscopy served to investigate goblet cell metaplasia and Clara cell morphological alterations. Results In non sensitized mice EC-UFP inhalation caused alterations in CC16 concentration, both at protein and mRNA level, and induced Clara cell hyperplasia. In sensitized mice, inhalation of EC-UFP prior to OVA challenge caused most significant alterations of BALF and serum CC16 concentration, BALF total protein and TNF-? relative expression compared to relevant controls; their Clara cells displayed the strongest morphological alterations and strongest goblet cell metaplasia occurred in the small airways. NAC strongly reduced both functional and morphological alterations of Clara cells. Conclusion Our findings demonstrate that oxidative stress plays an important role in EC-UFP-induced augmentation of functional and morphological alterations of Clara cells in allergic lung inflammation. PMID:20420656

2010-01-01

151

Vegetation collection efficiency of ultrafine particles: From single fiber to porous media  

NASA Astrophysics Data System (ADS)

A number of parameterization schemes are available to determine the collection efficiency of ultrafine particles (UFP) onto vegetated surfaces. One approach represents the vegetated elements as a fibrous filter with a characteristic fiber size that is difficult to a priori determine, while the other, a more conventional approach, represents vegetation as a porous medium. To date, no attempts have been made to compare the performance of these two distinct approaches or bridge them so as to show the necessary conditions leading to their potential equivalence. In a wind tunnel study, the UFP collection efficiencies of pine branches at five different wind speeds, two branch orientations, and two packing densities were measured and analyzed using these two vegetation representations. This vegetation type was selected because pines are a dominant species in the Southeastern United States and pine needles geometrically resemble fibrous material with a well-defined foliage diameter. The porous media and the fibrous filter representations described well observed UFP deposition at the branch scale. Conditions promoting their equivalence are thus explored. The difficult to determine effective fiber diameter was recovered from conventional canopy attributes such as the leaf area index by matching the collection efficiencies of UFP for the two vegetation representations. These results provide a working "aerodynamic" definition of the effective single-fiber diameter thereby rendering the simplified single-fiber formulation usable in large-scale atmospheric deposition models. Furthermore, the aerodynamic correction factor allows upscaling of pine needles to an effective leaf area index and provides some quantification of the effect of needle spatial clustering on UFP deposition. The applicability of the results to other vegetation species remains to be verified.

Lin, Ming-Yeng; Khlystov, Andrey; Katul, Gabriel G.

2014-01-01

152

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

153

Modeling population exposure to ultrafine particles in a major italian urban area.  

PubMed

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

154

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

155

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

156

Physicochemical properties and ability to generate free radicals of ambient coarse, fine, and ultrafine particles in the atmosphere of Xuanwei, China, an area of high lung cancer incidence  

NASA Astrophysics Data System (ADS)

The link between the high incidence of lung cancer and harmful pollutants emitted by local coal combustion in Xuanwei, Yunnan province, China, has been a focus of study since the 1980s. However, the mechanisms responsible for the high lung cancer rate remain unclear, necessitating further study. Since a close relationship between ambient air particle pollution and respiratory diseases exists, we sampled size-resolved ambient particles from the atmosphere of Xuanwei. In our indoor experiment, cutting-edge methods, including scanning electron microscopy coupled with energy dispersive X-ray detection (SEM/EDX), particle-induced X-ray emission (PIXE), electronic paramagnetic resonance (EPR) and the cell-free DCFH-DA assay, were employed to investigate the physicochemical properties, the potential to generate free radicals and the oxidative potential of ambient coarse (diameter, 1.8-10 ?m), fine (diameter, 0.1-1.8 ?m), and ultrafine (diameter, <0.1 ?m) particles. We found the total mass concentrations of the size-resolved particles collected in spring were higher than that in early winter. Mass percentage of fine particles accounted for 68% and 61% of the total particulate mass in spring and in early winter samples, respectively, indicating that fine particles were the major component of the Xuanwei ambient particulate matters. On the other hand, the results of SEM/EDX analysis showed that the coarse particles were dominated by minerals, the fine particles by soot aggregates and fly ashes, and the ultrafine particles by soot particles and unidentified particles. Our PIXE results revealed that crustal elements (Ca, Ti Si, Fe) were mainly distributed in coarse particles, while trace metals (Cr, Mn, Ni, Cu, Zn, Pb) dominated in the fine particle fraction, and S, a typical element emitted by coal combustion, mainly resided in fine particles collected from the winter atmosphere. EPR results indicated that the magnitude of free radical intensity caused by size-resolved particles followed these patterns: fine particles > coarse particles > ultrafine particles for spring samples and ultrafine particles > fine particles > coarse particles for winter samples. Cell-free DCFH assay results conclusively showed that all of the measured particle suspensions displayed a higher oxidative potential than the negative control. The correlation coefficient (R2) between free radical intensity and fluorescent intensity generated by the size-resolved particles was 0.535 and 0.507 for the spring and winter seasons, respectively, implying that ambient air particles in the Xuanwei atmosphere have the ability to generate free radicals, and fine and ultrafine particles could be hazardous to local residents.

Lu, Senlin; Yi, Fei; Hao, Xiaojie; Yu, Shang; Ren, Jingjing; Wu, Minghong; Jialiang, Feng; Yonemochi, Shinich; Wang, Qingyue

2014-11-01

157

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

158

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

PubMed Central

Background Evidence is needed regarding the air pollutant components and their sources responsible for associations between particle mass concentrations and human cardiovascular outcomes. We previously found associations between circulating biomarkers of inflammation and mass concentrations of quasi-ultrafine particles ? 0.25 ?m in aerodynamic diameter (PM0.25) in a panel cohort study of 60 elderly subjects with coronary artery disease living in the Los Angeles Basin. Objectives We reassessed biomarker associations with PM0.25 using new particle composition data. Methods Weekly biomarkers of inflammation were plasma interleukin-6 (IL-6) and soluble tumor necrosis factor-? receptor II (sTNF-RII) (n = 578). Exposures included indoor and outdoor community organic PM0.25 constituents [polycyclic aromatic hydrocarbons (PAHs), hopanes, n-alkanes, organic acids, water-soluble organic carbon, and transition metals]. We analyzed the relation between biomarkers and exposures with mixed-effects models adjusted for potential confounders. Results Indoor and outdoor PAHs (low-, medium-, and high-molecular-weight PAHs), followed by hopanes (vehicle emissions tracer), were positively associated with biomarkers, but other organic components and transition metals were not. sTNF-RII increased by 135 pg/mL [95% confidence interval (CI), 45–225 pg/mL], and IL-6 increased by 0.27 pg/mL (95% CI, 0.10–0.44 pg/mL) per interquartile range increase of 0.56 ng/m3 outdoor total PAHs. Two-pollutant models of PM0.25 with PAHs showed that nominal associations of IL-6 and sTNF-RII with PM0.25 mass were completely confounded by PAHs. Vehicular emission sources estimated from chemical mass balance models were strongly correlated with PAHs (R = 0.71). Conclusions Traffic emission sources of organic chemicals represented by PAHs are associated with increased systemic inflammation and explain associations with quasi-ultrafine particle mass. PMID:20123637

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

2010-01-01

159

Hygroscopic properties of ultrafine particles at an urban site in northern Japan during the summer of 2011  

NASA Astrophysics Data System (ADS)

To investigate the hygroscopic property of ultrafine particles, hygroscopic growth factors [g(RH)] of size-segregated atmospheric particles were measured at an urban site in Sapporo, northern Japan, during the summer of 2011. Hygroscopic growth factors at 85% RH [g(85%)] of freshly formed nucleation mode particles ranged from 1.11 to 1.28 with an average of 1.16 ± 0.06. These values are similar to those of secondary organic aerosols, suggesting that low volatile organic vapors are important to the growth of nucleated clusters into quasi-stable aerosol particles larger than 3 nm. Higher g(85%) values (range: 1.21-1.31, AVG: 1.27 ± 0.04) were obtained for grown Aitken mode nucleated particles. This result may indicate that the growth of freshly formed nucleation mode particles to the Aitken mode particles at the urban site can be attributed to condensation not only of low volatility organic vapors but also of highly water-soluble inorganic compounds like sulfuric acid. Diel variations in the number concentrations of less-hygroscopic particles [g(85%) <1.05] were similar to those in NO concentrations, suggesting that less-hygroscopic particles are mainly produced by local anthropogenic emissions such as traffic. Higher g(85%) values (1.27 ± 0.05) were obtained at a dry particle diameter of 120 nm when the air masses originated from downwind areas of the Asian continent, whereas lower g(85%) values (1.19 ± 0.06) were obtained when clean marine air masses arrived in the urban site. These results indicate that the hygroscopic property of large Aitken and small accumulation mode particles (80-165 nm) are highly influenced by the long-range transport of atmospheric particles.

Jung, Jinsang; Kawamura, Kimitaka

2013-04-01

160

Agglomerates of ultrafine particles of elemental carbon and TiO2 induce generation of lipid mediators in alveolar macrophages.  

PubMed Central

Agglomerates of ultrafine particles (AUFPs) may cause adverse health effects because of their large surface area. To evaluate physiologic responses of immune cells, we studied whether agglomerates of 77-nm elemental carbon [(EC); specific surface area 750 m2/g] and 21 nm titanium dioxide (TiO(2) particles (specific surface area 50 m(2)/g) affect the release of lipid mediators by alveolar macrophages (AMs). After 60-min incubation with 1 microg/mL AUFP-EC (corresponding to 7.5 cm(2) particle surface area), canine AMs (1 x 10(6) cells/mL) released arachidonic acid (AA) and the cyclooxygenase (COX) products prostaglandin E(2) (PGE(2), thromboxane B(2), and 12-hydroxyheptadecatrienoic acid but not 5-lipoxygenase (5-LO) products. AUFP-TiO(2) with a 10-fold higher mass (10 microg/mL) than AUFP-EC, but a similar particle surface area (5 cm(2) also induced AMs to release AA and COX products. Agglomerates of 250 nm TiO(2) particles (specific surface area 6.5 m(2)/g) at 100 microg/mL mass concentration (particle surface area 6.5 cm(2) showed the same response. Interestingly, 75 cm(2)/mL surface area of AUFP-EC and 16 cm(2)/mL surface area of AUFP-TiO(2) additionally induced the release of the 5-LO products leukotriene B(4) and 5-hydroxyeicosatetraenoic acid. Respiratory burst activity of stimulated canine neutrophils was partially suppressed by supernatants of AMs treated with various mass concentrations of the three types of particles. Inhibition of neutrophil activity was abolished by supernatants of AMs treated with COX inhibitors prior to AUFP-incubation. This indicates that anti-inflammatory properties of PGE(2) dominate the overall response of lipid mediators released by AUFP-affected AMs. In conclusion, our data indicate that surface area rather than mass concentration determines the effect of AUFPs, and that activation of phospholipase A(subscript)2(/subscript) and COX pathway occurs at a lower particle surface area than that of 5-LO-pathway. We hypothesize a protective role of PGE(2) in downregulating potential inflammatory reactions induced by ultrafine particles. PMID:11544173

Beck-Speier, I; Dayal, N; Karg, E; Maier, K L; Roth, C; Ziesenis, A; Heyder, J

2001-01-01

161

A hybrid chip based on aerodynamics and electrostatics for the size-dependent classification of ultrafine and nano particles.  

PubMed

Conventional virtual impactors experience a large pressure drop when they classify particles according to size, in particular ultrafine particles smaller than 100 nm in diameter. Therefore, most virtual impactors have been used to classify particles larger than 100 nm. Their cut-off diameters are also fixed by the geometry of their flow channels. In the proposed virtual impactor, particles smaller than 100 nm are accelerated by applying DC potentials to an integrated electrode pair. By the electrical acceleration, the large pressure drop could be significantly decreased and new cut-off diameters smaller than 100 nm could be successfully added. The geometric cut-off diameter (GCD) of the proposed virtual impactor was designed to be 1.0 microm. Performances including the GCD and wall loss were examined by classifying dioctyl sebacate of 100 to 600 nm in size and carbon particles of 0.6 to 10 microm in size. The GCD was measured to be 0.95 microm, and the wall loss was highest at 1.1 microm. To add new cut-off diameters, monodisperse NaCl particles ranging from 15 to 70 nm were classified using the proposed virtual impactor with applying a DC potential of 0.25 to 3.0 kV. In this range of the potential, the new cut-off diameters ranging from 15 to 35 nm was added. PMID:19704989

Kim, Yong-Ho; Park, Dongho; Hwang, Jungho; Kim, Yong-Jun

2009-09-21

162

Effect of ultrafine carbon black particles on lipoteichoic acid-induced early pulmonary inflammation in BALB/c mice  

SciTech Connect

We studied the interaction effects of a single intratracheal instillation of ultrafine carbon black (CB) particles and staphylococcal lipoteichoic acid (LTA) on early pulmonary inflammation in male BALB/c mice. We examined the cellular profile, cytokine and chemokine levels in the bronchoalveolar lavage (BAL) fluid, and expression of chemokine and toll-like receptor (TLR) mRNAs in lungs. LTA produced a dose-related increase in early pulmonary inflammation, which was characterized by (1) influx of polymorphonuclear neutrophils (PMNs) and (2) induction of interleukin (IL)-6, tumor necrosis factor (TNF)-{alpha}, macrophage inflammatory protein (MIP)-1{alpha}/CCL3, but no effect on monocyte chemoattractant protein (MCP)-1/CCL2 at 24 h after instillation. Levels of some proinflammatory indicators and TLR2-mRNA expression were significantly increased by 14 nm or 95 nm CB (125 {mu}g) and low-dose LTA (10 {mu}g) treatment compared to CB or LTA alone at 4 h after instillation. Notably, PMN levels and production of IL-6 and CCL2 in the 14 nm CB + LTA were significantly higher than that of 95 nm CB + LTA at 4 h after instillation. However, at 24 h after instillation, only PMN levels were significantly higher in the 14 nm CB + LTA than 95 nm CB + LTA but not the cytokines and chemokines. These data show additive as well as synergistic interaction effects of 14 nm or 95 nm ultrafine CB particles and LTA. We suggest that early pulmonary inflammatory responses in male BALB/c mice may be induced in a size-specific manner of the CB particles used in our study.

Yamamoto, Shoji [Environmental Health Sciences Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan)]. E-mail: snyamamo@nies.go.jp; Tin-Tin-Win-Shwe [Environmental Health Sciences Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Ahmed, Sohel [Environmental Health Sciences Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Kobayashi, Takahiro [Environmental Health Sciences Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Fujimaki, Hidekazu [Environmental Health Sciences Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan)

2006-06-15

163

Temperature dependence of long-term magnetization stability for data storage tapes prepared from ultrafine particles  

NASA Astrophysics Data System (ADS)

Time (t) dependence of the change in relative magnetization (?Mrela) for a period of 1000 h was investigated for advanced data storage metal particulate (MP) tape and Ba-ferrite (BF) sheets prepared from ultrafine articles at 295 to 338 K. Time dependence of ?Mrela at 295 K in all samples obeyed a logarithmic law for 1000 h. ?Mrela/log t at all temperatures for BF sheet was much larger than that of MP tape because of lower anisotropy field component. Relative permanent magnetization loss due to the oxidation for MP tape at 295 K was negligibly, however it increased as temperature increased.

Nishio, Hiroaki; Yamamoto, Hiroshi

164

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

EPA Science Inventory

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

165

The application of wavelet decomposition to quantify the local and regional sources of ultrafine particles in cities  

NASA Astrophysics Data System (ADS)

This study explores the application of wavelet decomposition as a means to distinguish between local and regional sources of ultrafine particles (UFP). Particle number concentrations were measured at a central site, two downtown sites, and four residential sites located across Toronto, Canada. Using a wavelet decomposition algorithm, particle concentration time series were separated into two signals: high frequency local-to-neighbourhood scale sources and low frequency urban-to-regional scale sources and processes. At the field sites, local-neighbourhood sources contributed between 13 and 32% of the total particle concentration. The urban-regional signal at each field site exhibited stronger correlation and greater homogeneity with respect to the central site than the original concentration time series. In contrast, the high frequency local-neighbourhood source signals exhibited limited correlation and high heterogeneity with respect to the central site. Traffic volume within a 2.5 km buffer explained 87% of the variability in the local-neighbourhood level signal observed between field sites while no significant association with traffic was found for the original particle number concentration data. This study has demonstrated that wavelet decomposition can be a useful tool for estimating exposure to UFP from local-neighbourhood and urban-regional scale sources and processes.

Sabaliauskas, Kelly; Jeong, Cheol-Heon; Yao, Xiaohong; Evans, Greg J.

2014-10-01

166

Fine and Ultrafine Particle Characterization and Modeling in High-Speed Milling of 6061-T6 Aluminum Alloy  

NASA Astrophysics Data System (ADS)

In this study, an experimental investigation was carried out on fine and ultrafine metallic dust emission during high-speed milling of 6061-T6 aluminum alloy in wet and dry conditions. Measurements of dust emission were conducted using a scanning mobility particle sizer spectrometer and an aerodynamic particle sizer spectrometer. These instruments were used to characterize particles in the micrometer and the nanometer size ranges. It was confirmed that the machining process produces nanoparticles as small as 10 nm and that the characteristics of the generated nanoparticles are not significantly influenced by the cutting conditions. The cutting forces and chip compression ratio were measured to validate the proposed dust generation model based on an energy approach. Good agreement was observed between the model and the experimental measurements for the investigated conditions. It was demonstrated that the majority of generated dust is caused by deformations in the primary shear zone. In addition, the percentage of generated dust is significantly influenced by deformation conditions in the chip formation zone. It was found that high cutting speeds could reduce the percentage of the generated particles during the milling process.

Zaghbani, Imed; Songmene, Victor; Khettabi, Riad

2009-02-01

167

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

168

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

169

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

170

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

NASA Astrophysics Data System (ADS)

Representing the formation and growth of ultrafine particles in chemistry and climate models is challenging due to the complexity of processes involved, which leads to uncertainties in aerosol size distributions and their effects on Cloud Condensation Nuclei (CCN). The Rocky Mountain Biogenic Aerosol Study (RoMBAS) was an intensive measurement campaign as part of the broader BEACHON (Bio-hydro-atmosphere interactions of Energy Aerosols, Carbon, H2O, Organics and Nitrogen) project. This took place during July - August 2011 at the Manitou Experimental Forest Observatory. The location is situated in the rural-urban interface along the Colorado Front Range and allows us to study the effects of aerosol formation and other atmospheric chemistry phenomenon in a forested region with periodic urban influences. Surface measurements of gases, aerosols and meteorological parameters from this campaign were used to examine the formation and growth processes leading to observed Aiken-mode Particle burst Events (APEs), and to quantify their effects on aerosol properties and cloud condensation nuclei CCN concentrations. Results suggest that APEs were observed at the forest site in the early afternoon associated with the arrival of anthropogenic plumes from Denver and Colorado Springs. Mean number concentrations of ultrafine particles (4-30nm) typically exceeded 5000 cm-3 during APEs and these elevated concentrations were correlated with elevated SO2. The Weather Research and Forecasting model with on-line Chemistry (WRF-Chem) was used to model APEs during BEACHON-RoMBAS. The model was updated to include an activation nucleation (AN) scheme with an empirical representation of aerosol nucleation rate, and subsequent growth due to the condensation of organic and inorganic vapors. Comparisons with ground measurements show that the updated model reasonably captures aerosol number concentrations and size distribution during APEs, as well as CN and CCN concentrations. Model results suggest that anthropogenic SO2 trigger APEs, and that the condensation of monoterpene oxidation products onto freshly nucleated particles drives their growth. The simulated growth rate is 1.2 nm/hr which is comparable with 2 nm/hr in the measurement. Comparing with a sensitivity test excluding nucleation process in the model, model calculations with AN show the presence of APEs in the forest area tends to modify the composition of small aerosols (<100nm), leading to 2.3 times higher values of sulfate aerosols.Therefore, the predicted volume-averaged hygroscopicity parameter and CCN concentration are significantly influenced.

Cui, Y.; Hodzic, A.; Smith, J. N.; Ortega, J. V.; de Foy, B.

2013-12-01

171

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

172

PROCEEDINGS ON SYNCHROTRON RADIATION: Size distribution of sulfur species in fine and ultrafine aerosol particles using sulfur K-edge XANES  

NASA Astrophysics Data System (ADS)

The sulfur species existing in different size aerosol particles were determined based on the 'white line' energy shift and the features of post edge structure of sulfur K-edge XANES (X-ray Absorption Near Edge Structure). The results indicated that sulfates were dominant sulfur species in aerosol particles. However, small amount of reductive sulfur species were also found in the ultrafine aerosol particles(<0.1 ?m). Sulfates in aerosols mostly exhibited as (NH4)2SO4 and gypsum. Most (NH4)2SO4 distributed in aerosol particles finer than 0.952 ?m, while gypsum was the dominant sulfate in coarse aerosols.

Lin, Jun; Bao, Liang-Man; Liu, Wei; Li, Yan; Li, Yu-Lan; Ma, Chen-Yan; Zhao, Yi-Dong

2009-11-01

173

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

174

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

175

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

PubMed Central

Background: Mechanisms underlying previously reported air pollution and cardiovascular (CV) morbidity associations remain poorly understood. Objectives: We examined associations between markers of pathways thought to underlie these air pollution and CV associations and ambient particle concentrations in postinfarction patients. Methods: We studied 76 patients, from June 2006 to November 2009, who participated in a 10-week cardiac rehabilitation program following a recent (within 3 months) myocardial infarction or unstable angina. Ambient ultrafine particle (UFP; 10–100 nm), accumulation mode particle (AMP; 100–500 nm), and fine particle concentrations (PM2.5; ? 2.5 ?m in aerodynamic diameter) were monitored continuously. Continuous Holter electrocardiogram (ECG) recordings were made before and during supervised, graded, twice weekly, exercise sessions. A venous blood sample was collected and blood pressure was measured before sessions. Results: Using mixed effects models, we observed adverse changes in rMSSD [square root of the mean of the sum of the squared differences between adjacent normal-to-normal (NN) intervals], SDNN (standard deviation of all NN beat intervals), TpTe (time from peak to end of T-wave), heart rate turbulence, systolic and diastolic blood pressures, C-reactive protein, and fibrinogen associated with interquartile range increases in UFP, AMP, and PM2.5 at 1 or more lag times within the previous 5 days. Exposures were not associated with MeanNN, heart-rate–corrected QT interval duration (QTc), deceleration capacity, and white blood cell count was not associated with UFP, AMP, and PM2.5 at any lag time. Conclusions: In cardiac rehabilitation patients, particles were associated with subclinical decreases in parasympathetic modulation, prolongation of late repolarization duration, increased blood pressure, and systemic inflammation. It is possible that such changes could increase the risk of CV events in this susceptible population. PMID:22542955

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

2012-01-01

176

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

Microsoft Academic Search

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

Rongsong Li; Zhi Ning; Rohit Majumdar; Jeffery Cui; Wakako Takabe; Nelson Jen; Constantinos Sioutas; Tzung Hsiai

2010-01-01

177

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

178

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

PubMed

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

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

2013-01-01

179

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

180

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

181

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

PubMed

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

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

2013-01-01

182

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

PubMed Central

Particulate matter (PM) is an important risk factor for asthma. Generation of oxidative stress by PM is a major mechanism of its health effects. Transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) mediates antioxidant and phase II enzymes and is essential in protecting against oxidative stress and lung inflammation. We have previously shown that ambient ultrafine particles (UFP) could exert a potent adjuvant effect on allergic sensitization to ovalbumin (OVA) in mice. We hypothesized that Nrf2 deficiency in dendritic cells (DC) could enhance the adjuvant potential of UFP on allergic sensitization. We show that the adjuvant effect of intranasally instilled UFP is significantly enhanced in Nrf2 knockout (Nrf2-/-) mice compared with their wild-type (Nrf2+/+) counterparts. Under resting conditions Nrf2-/- DC displayed an intrinsic predilection to a T-helper 2 (Th2)-favoring cytokine profile characterized by low level of IL-12p70 and high level of IL-6 as compared to Nrf2+/+ DC. Adoptive transfer of OVA/UFP-treated Nrf2-/- DC provoked a more severe allergic inflammation in the lung than Nrf2+/+ DC in the same treatment group. We conclude that Nrf2 deficiency in DC may promote a constitutive immune-polarizing cytokine milieu, which we propose may have contributed to the augmented adjuvant effect of UFP on allergic sensitization. PMID:23595026

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

2014-01-01

183

Electrostatic precipitation of ultrafine particles enhanced by simultaneous diffusional deposition on wire screens.  

PubMed

A laboratory-scale electrostatic precipitator has been designed and constructed in which the grounded collector plate has been substituted by a set of wire screens placed perpendicularly to the gas flow. Particles are deposited onto the screens by two mechanisms--electrostatic deposition and diffusional deposition--which act simultaneously. On the one hand, electrostatic deposition is effective for relatively large particles, but it is quite ineffective for the smallest ones because their charging probability in the corona field is too low. On the other hand, the diffusional collection efficiency of particles on fibers is high for small particles but low for the larger ones. Therefore, the simultaneous diffusional-electrostatic precipitation may become a useful technique for efficient filtration of particles below 0.1 microm. A preliminary experimental evaluation of this filtering device has shown that submicrometer particles with diameters down to a few nanometers can be collected with number efficiencies greater than 99%. PMID:12469721

Alonso, Manuel; Alguacil, Francisco José

2002-11-01

184

Size distribution and emission rate measurement of fine and ultrafine particle from indoor human activities  

Microsoft Academic Search

Human indoor activities generate airborne particles which contribute to the increase of aerosol concentration levels in the home. The particle size distribution emission rate was measured for 18 different activities (burning candle or incense, cooking, spray use, computer printing and household cleaning). The particle emission rate was calculated from concentration measurements with a DMS500 (CAMBUSTION) in an experimental chamber (2.36±0.05m3).

Evelyne Géhin; Olivier Ramalho; Séverine Kirchner

2008-01-01

185

Redox Dynamics of Mixed Metal (Mn, Cr, and Fe) Ultrafine Particles  

Microsoft Academic Search

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

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

2009-01-01

186

Influence of temperature on fractal dimension of dynamic scattered light intensity signal of ultrafine particles  

NASA Astrophysics Data System (ADS)

The fluctuation of the dynamic scattered light of particles was characterized with fractal dimensions, and the influence of temperature on the fractal dimension was discussed. In the experiments, the fractal dimensions of dynamic scattered light intensity signal of particles with the diameter of 60nm, 90nm, 200nm, 300nm and 450nm, were obtained under the temperatures of 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C. The experimental results shown the monotony relationship between fractal dimension of scattered light intensity signal of particles and the temperature in the particle system, which indicate that the fractal dimension of scattered light signal correlate well not only with the particle size but also the temperature of the suspension. Under the condition of constant temperature in the cuvette, the smaller the particles, the larger their fractal dimensions. For the same particle system, the higher the temperature, the larger the fractal dimensions of dynamic scattered light. By using two-dimensional interpolation surface chart of fractal dimensions, the polydisperse particle system were measured.

Shen, Jin; Tan, Boxue; Ding, Qiang; Yang, Shulian

2008-03-01

187

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

188

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

189

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

190

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

191

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

192

Measurement of Ultrafine Particle Size Distributions from Coal, Oil, and Gas-Fired Stationary Combustion Sources  

Microsoft Academic Search

Currently, we have limited knowledge of the physical and chemical properties of emitted primary combustion aerosols and the changes in those properties caused by nucleation, condensation growth of volatile species, and particle coagulations under dilution and cooling in the ambient air. A dilution chamber was deployed to sample exhaust from a pilot-scale furnace burning various fuels at a nominal heat

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

2004-01-01

193

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

194

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

195

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

196

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

197

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

198

Simple and rapid HPLC-UV method using an ultrafine particle octadecylsilane for determination of residual fentanyl in applied Durotep MT transdermal matrix patches and its clinical application.  

PubMed

A few complicated and time-consuming methods are available for the determination of residual fentanyl in Durotep MT transdermal patches, however, their application to clinical settings is limited. The aim of this study was to develop a simple and rapid HPLC-UV method using an ultrafine particle octadecylsilane (ODS) for the determination of residual fentanyl in applied Durotep MT transdermal matrix patches. Patch extraction involved sonicating a shredded Durotep MT patch in acetonitrile for 15 min. Fentanyl separation was completed within 2 min using a 2.3-?m particle ODS column (50 × 4.6 mm i.d.) at a flow rate of 1.5 mL/min. No peaks interfering with fentanyl (1.27 min) and papaverine (0.89 min) as an internal standard were observed. The calibration curve for fentanyl was linear over the range of 0.015-9.0 mg as a Durotep MT patch. The intra- and inter-assay precisions and accuracies of each patch were within 5.3% and 103.9-110.5% and within 8.2% and 97.1-104.3%, respectively. The validated method was applied to determine residual fentanyl in Durotep MT patches used in 35 cancer patients. Although the plasma fentanyl concentration was significantly correlated with its measured absorption rate, the measured absorption rate normalized fentanyl concentration showed a large inter-individual variation. The validated simple and rapid HPLC-UV method established in the present study is helpful for evaluating the absorption rate of fentanyl in patients receiving Durotep MT patches. PMID:22223375

Naito, Takafumi; Takashina, Yoshiaki; Yagi, Tatsuya; Kawakami, Junichi

2012-01-01

199

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

200

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

201

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

202

FORMATION OF FINE PARTICLES FROM RESIDUAL OIL COMBUSTION: REDUCING ULTRAFINE NUCLEI THROUGH THE ADDITION OF INORGANIC SORBENT  

EPA Science Inventory

The paper gives results of an investigation, using an 82-kW-rated laboratory-scale refractory-lined combustor, of the characteristics of particulate matter emitted from residual oil combustion and the reduction of ultrafine nuclei by postflame sorbent injection. Without sorbent a...

203

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

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

204

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

PubMed

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 gas furnace) to indoor UFP exposures. We conducted a cross-sectional survey in 36 homes in the cities of Montréal, Québec, and Pembroke, Ontario. Real-time measures of indoor UFP concentrations were collected in each home for approximately 14 h, and an outdoor UFP measurement was collected outside each home before indoor sampling. A home-characteristic questionnaire was also administered, and air exchange rates were estimated using carbon dioxide as a tracer gas. Average UFP exposures of 21,594 cm(-3) (95% confidence interval (CI): 14,014, 29,174) and 6660 cm(-3) (95% CI: 4339, 8982) were observed for the evening (1600-2400) and overnight (2400-0800) hours, respectively. In an unadjusted comparison, overnight baseline UFP exposures were significantly greater in homes with electric baseboard heaters as compared to homes using forced-air oil or natural gas furnaces, and homes using wood stoves had significantly greater overnight baseline UFP exposures than homes using forced-air natural gas furnaces. However, in multivariate models, electric oven use (beta=12,253 cm(-3), 95% CI: 3524, 20,982), indoor relative humidity (beta=1136 cm(-3) %, 95% CI: 372, 1899), and indoor smoking (beta=18,192 cm(-3), 95% CI: 2073, 34,311) were the only significant determinants of mean indoor UFP exposure, whereas air exchange rate (beta=4351 cm(-3) h(-1), 95% CI: 1507, 7195) and each 10,000 cm(-3) increase in outdoor UFPs (beta=811 cm(-3), 95% CI: 244,1377) were the only significant determinants of overnight baseline UFP exposures. In general, our findings suggest that home heating systems are not important determinants of indoor UFP exposures. PMID:17033678

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

2007-05-01

205

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

PubMed

The contemporary urban environment has become increasingly complex in its composition, leading to discussions regarding possible novel health effects. Two factors that recently have received considerable attention are ultrafine particles (UFP; <0.1 microm) produced by combustion processes and emissions from wireless communication devices like mobile phones that emit in the radio-frequency (RF) part of the spectrum. Several studies have shown biological effects of both these exposures in various cell systems. Here we investigate if exposure to UFP (12-14 nm, 100 microg/ml) and RF-electromagnetic fields (EMF; 2 W/kg specific absorption rate (SAR); continuous wave (CW) or modulated (217Hz or GSM-nonDTX)), alone or in combination influences levels of the superoxide radical anion or the stress protein heat-shock protein (Hsp70) in the human monocyte cell line Mono Mac 6. Heat treatment (42-43 degrees C, 1h) was used as positive control for both stress reaction and for heat development in the RF exposure setup. Our results clearly show that Mono Mac 6 cells are capable to internalise UFP, and that this phagocytic activity is connected to an increased release of free radicals. This increase (40-45% above negative control) is stronger than the effect of heat treatment. On the other hand, none of the employed RF exposures showed any effects on free radical levels. Co-exposure of RF and UFP did not potentiate the UFP effect either. Our investigations showed a significantly increased Hsp70 expression level by heat treatment in a time-dependent manner, whereas UFP, RF, or UFP+RF were without any effect. Therefore, we conclude that in the investigated Mono Mac 6 cells, RF exposure alone or in combination with UFP cannot influence stress-related responses. PMID:16153791

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

2006-02-01

206

Development of Ultrafine, Lamellar Structures in Two-Phase {gamma}-TiAl Alloys  

SciTech Connect

Processing of two-phase gamma-TiAl alloys (Ti-47Al-2Cr-2Nb or minor modifications thereof) above the alpha-transus temperature (T {sub alpha}) produced unique refined-colony/ultrafine lamellar structures in both powder- and ingot-metallurgy (P/M and I/M, respectively) alloys. These ultrafine lamellar structures consist of fine laths of the gamma and alpha {sub 2} phases, with average interlamellar spacings (lambda {sub Lambda}) of 100-200 nm and alpha {sub 2}-alpha {sub 2} spacings (lambda {sub alpha}) of 200-500 nm, and are dominated by gamma/alpha {sub 2} interfaces. This characteristic microstructure forms by extruding P/M Ti-47Al-2Cr-2Nb alloys above T {sub alpha}, and also forms with finer colony size but slightly coarser fully-lamellar structures by hot-extruding similar I/M alloys. Alloying additions of B and W refine lambda {sub L} and lambda {sub alpha} in both I/M Ti-47Al (cast and heat-treated above T {sub alpha}) or in extruded Ti-47Al-2Cr-2Nb alloys. The ultrafine lamellar structure in the P/M alloy remains stable during heat-treatment at 900 {degrees}C for 2h, but becomes unstable after 4h at 982 {degrees}C; the ultrafine lamellar structure remains relatively stable after aging for {gt}5000 h at 800 {degrees}C. Additions of B+W dramatically improve the coarsening resistance of lambda L and lambda alpha in the I/M Ti-47Al alloys aged for 168 h at 1000{degrees}C. In both the P/M and I/M Ti-47Al-2Cr-2Nb alloys, these refined-colony/ultrafine-lamellar structures correlate with high strength and good ductility at room temperature, and very good strength at high temperatures. While refining the colony size improves the room-temperature ductility, alloys with finer lambda {sub L} are stronger at both room- and high-temperatures. Additions of B+W produce finer as-processed lambda {sub L} and lambda {sub alpha} in I/M TiAl alloys, and stabilize such structures during heat-treatment or aging.

Maziasz, P.J., Liu, C.T.

1997-12-31

207

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

208

Hygroscopic properties of newly formed ultrafine particles at an urban site surrounded by a deciduous forest in northern Japan during the summer of 2011  

NASA Astrophysics Data System (ADS)

To investigate the hygroscopic property of ultrafine particles during the new particle formation event, hygroscopic growth factors (g(RH)) of size-segregated atmospheric particles were measured at an urban site in Sapporo, northern Japan, during the summer of 2011. Hygroscopic growth factors at 85% RH (g(85%)) of freshly formed nucleation mode particles were measured at a dry particle diameter (Dp) centered at 20 nm to be 1.11 to 1.28 (average 1.16 ± 0.06), which are equivalent to 1.17 to 1.35 (1.23 ± 0.06) for a dry Dp centered at 100 nm after considering the Kelvin effect. These values are comparable with those of secondary organic aerosols, suggesting that low-volatility organic vapors are important to the burst of nucleation mode particles at the measurement site surrounded by a deciduous forest. Gradual increases in mode diameter after the burst of nucleation mode particles were obtained under southerly wind condition with a dominant contribution of intermediately-hygroscopic particles. However, sharp increases in mode diameter were obtained when wind direction shifted to northwesterly or northeasterly with a sharp increase in highly-hygroscopic particle faction in the Aitken mode particles, indicating that local wind direction is an important factor controlling the growth of newly formed particles and their hygroscopic properties. Higher g(85%) values (1.27 ± 0.05) were obtained at a dry Dp of 120 nm when the air masses originated from the Asian Continent, whereas lower g(85%) values (1.19 ± 0.06) were obtained when clean marine air masses arrived at the urban site. These results indicate that the hygroscopic property of large Aitken and small accumulation mode particles (80-165 nm) is highly influenced by the long-range atmospheric transport of particles and their precursors.

Jung, J.; Kawamura, K.

2014-03-01

209

The effect of dilution on the quantitative measurement of bubbles in high-density ultrafine bubble-filled water using the light scattering method  

NASA Astrophysics Data System (ADS)

We have developed an ultrafine bubble generating system, ultrafineGALF, upgrading the microGALF system to a flow rate of 0.24 m3/h. The ultrafineGALF system can generate a dense population of more than 109 ultrafine bubbles per ml. The density and size distribution of these bubbles have been measured using a NanoSight measuring instrument, but precision measurement of the number density has become difficult because it now extends beyond the measuring range (1×109/ml) of this instrument. Thus far, the number density of the ultrafine bubbles after dilution has been measured, but few reports are available on the effect of dilution on gas particles, which behave differently from solid particles. In this study, the effect of dilution, which is required to measure the density of ultrafine bubbles at ultra-high densities, was investigated. No large differences due to the use of dilution among three types of samples with different concentrations of ultrafine bubbles were found, although the samples did show slightly different rates of change in the concentration of ultrafine bubbles over time.

Maeda, Shigeo; Kobayashi, Hideaki; Ida, Katsuhisa; Kashiwa, Masakazu; Nishihara, Ikkan; Fujita, Toshihiro

2014-08-01

210

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

NASA Astrophysics Data System (ADS)

The collection efficiency of electrostatic precipitators for the submicron particles ranging from 0.1 to 1 ?m and ultrafine particles smaller than 0. l?m is below the requirements of new PM2.5 emission regulations. In this work, numerical and experimental studies were conducted to examine the effect of discharge and collecting electrode geometries on the ion density and electric field profiles and consequently their effect on the particle surface charge and collection efficiency. The collection efficiency prediction was based on a modified Deutsche's equation after calculation of three dimensional electric field and ion density profiles. Whereas, the particle surface charge was obtained from diffusion and field charging models. Results show that the collection efficiency of fine particles for the spike-type discharge electrode when compared to the conventional wire-type was improved. Experimental validations were conducted on a bench scale electrostatic precipitator for total and partial collection efficiency of particles ranging in size from 0.01 to 20 ?m and the results indicated that the model can be effectively applied for prototype design, modification, and scale-up of collecting and discharge electrodes.

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

2008-12-01

211

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

212

Seasonal and spatial variation in dithiothreitol (DTT) activity of quasi-ultrafine particles in the Los Angeles Basin and its association with chemical species.  

PubMed

A year-long sampling campaign of quasi-ultrafine particles (dp < 0.25 ?m) was conducted at 10 distinct sites representing source, urban and/or near-freeway, rural receptor and desert locations across the Los Angeles air basin. Redox activity of the PM samples was measured by means of the Dithiothreitol (DTT) assay and detailed chemical analysis was performed to measure the concentrations of chemical species. DTT activity per unit air volume and unit PM mass (expressed in nmol min(-1) m(-3) and nmol/min/?g PM, respectively) showed similar trends across sites and seasons. DTT activity was generally higher during cold seasons (winter and fall) compared to warm seasons (summer and spring). Noticeable peaks were observed at urban near-freeway locations representing "source" sites impacted by fresh traffic emissions. Regression analysis indicated strong association (R > 0.7) between the DTT activity and the concentrations of carbonaceous species (OC, EC, WSOC and WIOC) across all seasons and strong winter-time correlations with organic tracers of primary vehicular emissions including polycyclic aromatic hydrocarbons (PAHs), alkanes, hopanes and steranes. Strong correlations were also observed, particularly during winter, between DTT activity and transition metals (e.g., Cr, Mn, V, Fe, Cu, Cd and Zn), which share similar vehicular sources with primary organics. A multivariate linear regression analysis indicated that the variability in DTT activity is best explained by the variability in concentrations of WSOC, WIOC, EC and hopanes. Combined contributions from these species explained 88% of the DTT activity. The appearance of WSOC as a typical tracer of secondary organic aerosol, along with EC, WIOC and hopanes, all markers of emissions from primary combustion sources, emphasizes the contributions of both primary and secondary sources to the overall oxidative potential of quasi-ultrafine particles. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Environmental Science and Health, Part A, to view the supplemental file. PMID:24345242

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

2014-01-01

213

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

214

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

PubMed Central

Background Exposure to ultrafine particles exerts diverse harmful effects including aggravation of pulmonary diseases like asthma. Recently we demonstrated in a mouse model for allergic airway inflammation that particle-derived oxidative stress plays a crucial role during augmentation of allergen-induced lung inflammation by ultrafine carbon particle (UfCP) inhalation. The mechanisms how particle inhalation might change the inflammatory balance in the lungs, leading to accelerated inflammatory reactions, remain unclear. Lipid mediators, known to be immediately generated in response to tissue injury, might be strong candidates for priming this particle-triggered change of the inflammatory balance. Methods We hypothesize that inhalation of UfCP may disturb the balance of pro- and anti-inflammatory lipid mediators in: i) a model for acute allergic pulmonary inflammation, exposing mice for 24 h before allergen challenge to UfCP inhalation (51.7 nm, 507 ?g/m3), and ii) an in-vitro model with primary rat alveolar macrophages (AM) incubated with UfCP (10 ?g/1 x 106 cells/ml) for 1 h. Lungs and AM were analysed for pro- and anti-inflammatory lipid mediators, namely leukotriene B4 (LTB4), prostaglandin E2 (PGE2), 15(S)-hydroxy-eicosatetraenoic acid (15(S)-HETE), lipoxin A4 (LXA4) and oxidative stress marker 8-isoprostane by enzyme immunoassays and immunohistochemistry. Results In non-sensitized mice UfCP exposure induced a light non-significant increase of all lipid mediators. Similarly but significantly in rat AM all lipid mediators were induced already within 1 h of UfCP stimulation. Also sensitized and challenge mice exposed to filtered air showed a partially significant increase in all lipid mediators. In sensitized and challenged mice UfCP exposure induced highest significant levels of all lipid mediators in the lungs together with the peak of allergic airway inflammation on day 7 after UfCP inhalation. The levels of LTB4, 8-isoprostane and PGE2 were significantly increased also one day after UfCP exposure. Immunohistochemistry localized highest concentrations of PGE2 especially in AM one day after UfCP exposure. Conclusion Our results suggest that UfCP exposure affects the balance between pro- and anti-inflammatory lipid mediators. In allergic mice, where the endogenous balance of pro- and anti-inflammatory mediators is already altered, UfCP exposure aggravates the inflammation and the increase in anti-inflammatory, pro-resolving lipid mediators is insufficient to counterbalance the extensive inflammatory response. This may be a contributing mechanism that explains the increased susceptibility of asthmatic patients towards particle exposure. PMID:22809365

2012-01-01

215

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

NASA Astrophysics Data System (ADS)

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 circulation and the use of in-duct filters such as electrostatic precipitators (ESP) and fibrous mechanical filters (MECH). Deposition rates are calculated for 128 size categories ranging from 0.01 to 2.5 ?m. More than 110 separate "events" (mostly cooking, candle burning, and pouring kitty litter) were used to calculate deposition rates for four conditions: fan off, fan on, MECH installed, ESP installed. For all cases, deposition rates varied in a "U"-shaped distribution with the minimum occurring near 0.1 ?m, as predicted by theory. The use of the central fan with no filter or with a standard furnace filter increased deposition rates by amounts on the order of 0.1-0.5 h -1. The MECH increased deposition rates by up to 2 h -1 for ultrafine and fine particles but was ineffective for particles in the 0.1-0.5 ?m range. The ESP increased deposition rates by 2-3 h -1 and was effective for all sizes. However, the ESP lost efficiency after several weeks and needed regular cleaning to maintain its effectiveness. A reduction of particle levels by 50% or more could be achieved by use of the ESP when operating properly. Since the use of fans and filters reduces particle concentrations from both indoor and outdoor sources, it is more effective than the alternative approach of reducing ventilation by closing windows or insulating homes more tightly. For persons at risk, use of an air filter may be an effective method of reducing exposure to particles.

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

216

Development of the Electroacoustic Dewatering (EAD) process for fine/ultrafine coal: First quarterly progress report, period ending December 15, 1988  

SciTech Connect

Battelle, in cooperation with the Electric Power Research Institute (EPRI), Ashbrook-Simon-Hartley (ASH), Kaiser Engineers (KE), Lewis Corporation, and Prof. S.H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to a commercial belt filter press design that is used in many other applications. 1 fig.

Not Available

1989-01-05

217

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...

218

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

NASA Astrophysics Data System (ADS)

The lack of scientific evidence on the constituents, properties, and health effects of second-hand waterpipe smoke has fueled controversy over whether public smoking bans should include the waterpipe. The purpose of this study was to investigate and compare emissions of ultrafine particles (UFP, <100 nm), carcinogenic polyaromatic hydrocarbons (PAH), volatile aldehydes, and carbon monoxide (CO) for cigarettes and narghile (shisha, hookah) waterpipes. These smoke constituents are associated with a variety of cancers, and heart and pulmonary diseases, and span the volatility range found in tobacco smoke. Sidestream cigarette and waterpipe smoke was captured and aged in a 1 m 3 Teflon-coated chamber operating at 1.5 air changes per hour (ACH). The chamber was characterized for particle mass and number surface deposition rates. UFP and CO concentrations were measured online using a fast particle spectrometer (TSI 3090 Engine Exhaust Particle Sizer), and an indoor air quality monitor. Particulate PAH and gaseous volatile aldehydes were captured on glass fiber filters and DNPH-coated SPE cartridges, respectively, and analyzed off-line using GC-MS and HPLC-MS. PAH compounds quantified were the 5- and 6-ring compounds of the EPA priority list. Measured aldehydes consisted of formaldehyde, acetaldehyde, acrolein, methacrolein, and propionaldehyde. We found that a single waterpipe use session emits in the sidestream smoke approximately four times the carcinogenic PAH, four times the volatile aldehydes, and 30 times the CO of a single cigarette. Accounting for exhaled mainstream smoke, and given a habitual smoker smoking rate of 2 cigarettes per hour, during a typical one-hour waterpipe use session a waterpipe smoker likely generates ambient carcinogens and toxicants equivalent to 2-10 cigarette smokers, depending on the compound in question. There is therefore good reason to include waterpipe tobacco smoking in public smoking bans.

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

2010-01-01

219

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

Microsoft Academic Search

Micronised TiO2 particles with a diameter of about 15 nm are used in sunscreens as physical UV filter. Due to the small particle size it may be supposed that TiO2 particles can pass through the uppermost horny skin layer (stratum corneum) via intercellular channels and penetrate into deeper vital skin layers. Accumulations of TiO2 particles in the skin can decrease

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

2004-01-01

220

Nano-porous TiO2 layer using ultrafine nano-particles for the blocking layer in dye-sensitized solar cells.  

PubMed

A nano-porous TiO2 layer was produced by spray-deposition using ultrafine anatase nano-particles for the blocking layer for the dye-sensitized solar cells (DSCs). The microstructure and the electrochemical properties of the spray-deposited TiO2 layer were examined. The results of electrochemical properties showed that the spray-deposited TiO2 layer was capable to suppress the I3- ions diffusion to FTO substrate, reducing the electron recombination between the electrons on FTO substrate and I3- ions in electrolyte. In addition, the connection between TiO2 film and FTO substrate was improved by the TiO2 layer. Therefore, the short circuit current density and thereby the photo-to-electric energy conversion efficiency were improved by this blocking layer. The blocking effect of the porous layer was attributed to both the complicated pore structure of the spray-deposited layer and the enhanced connections between TiO2 film and FTO substrate. The low temperature characteristic of spray deposition approach indicates that it is suitable to the flexible-based DSCs. PMID:24734697

Yao, Hai-Long; Ma, Jun-Hua; Yang, Guan-Jun; He, Xue-Long; Fan, Sheng-Qiang; Li, Cheng-Xin; Li, Chang-Jiu

2014-04-01

221

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

222

The effects of leaf area density variation on the collection efficiency of black carbon in the size range of ultrafine particles (UFP)  

NASA Astrophysics Data System (ADS)

Black carbon is mainly produced in the ultra-fine particle (UFP) size range of 10-100 nm from combustion processes and is now receiving significant attention given its role in global and regional climate change, cloud physics, human health and respiratory related diseases. Likewise, the role of vegetated surfaces in removing UFP is drawing increased attention, prompting interest in the relationship between leaf area density and UFP collection efficiency. Here, carbonaceous particles, mainly black carbon, were generated by burning candles during "sooting burn" to explore the effects of leaf area density (LAD) variation on the collection efficiency of black carbon in the UFP size range. Three scenarios were explored in a wind tunnel: (1) Juniperus Chinensis branches that are uniformly distributed within the test section; (2) LAD that is linearly increasing with downwind distance and (3) LAD that is decreasing with downwind distance. The total leaf area index (LAI) was maintained constant in all three cases. Particle concentrations were measured at multiple locations within the vegetated volume for a range of sizes of UFP (12.6-102 nm) using Scanning Mobility Particle Sizer (SMPS). The measured concentration can be used to evaluate the performance of a size-resolving model that couples the turbulent flow field and the collection efficiency for the variable LAD. The model assumes that (i) the mean longitudinal momentum balance is controlled only by the interplay between drag force and the pressure gradient, and (ii) the dominant collection mechanism for UFP is Brownian diffusion. Hence, other collection mechanisms such as inertial impaction, interception and phoretic effects are negligible. Good agreement was found between the model calculations of the UFP collection efficiency by the vegetation and the wind tunnel measurements for all three cases and across a wide range of wind speeds and particle size. It was shown that variations in leaf area density lead to a modification in the mean pressure gradient, resulting in an adjustment in the drag coefficient via the mean momentum balance. Once this adjustment is accounted for, the over-all particle collection efficiency is governed by the integrated LAD.

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

2012-12-01

223

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

224

Development of Particle Flow Calorimetry  

E-print Network

This talk reviews the development of imaging calorimeters for the purpose of applying Particle Flow Algorithms (PFAs) to the measurement of hadronic jets at a future lepton collider. After a short introduction, the current status of PFA developments is presented, followed by a review of the major developments in electromagnetic and hadronic calorimetry.

Jose Repond

2011-10-10

225

Magnetic field effect on gas-phase synthesis of metal-containing ultrafine particles from iron pentacarbonyl and carbon disulfide  

Microsoft Academic Search

From a gaseous mixture of Fe(CO)5 and CS2, sedimentary aerosol particles involving organometal compounds were produced under UV light irradiation at 313nm. Chemical composition of the sedimentary aerosol particles was controlled by a magnetic field and by post-exposure with UV light. By applying a magnetic field up to 5T, photochemical reactivity of Fe(CO)5 molecules was promoted and the amount of

Hiroshi Morita; Youjirou Takeyasu; Hironori Okamura; Hiroaki Ishikawa

2006-01-01

226

The developing respiratory tract and its specific needs in regard to ultrafine particulate matter exposure.  

PubMed

Nanoparticles have unique physico-chemical properties compared to larger particles that have the potential to provide promising new possibilities for biomedical applications. Considerable research is currently exploring these potentials of nanotechnology. In contrast, airborne particles as components of indoor air, ambient air pollution associated with traffic-related pollution, industry, power plants, and other combustion sources have the potential to harm children's health. However, a similar research effort into the potential health effects of exposure to nanoparticles is lacking. Children differ markedly from adults in their developmental biology rendering young children the most vulnerable group with regard to potentially harmful effects induced by particulate exposure. This review discusses the differences between children and adults in regard to nanoparticle exposure highlighting the uniqueness and vulnerability of children. PMID:22475255

Schüepp, Karen; Sly, Peter D

2012-06-01

227

Development of the electroacoustic dewatering (EAD) process for fine/ultrafine coal: Second quarterly progress report period ending 31 March 1989  

SciTech Connect

Battelle, in cooperation with the Electric Power Research Institute (EPRI), Ashbrook-Simon-Hartley (ASH), Kaiser Engineers (KE), Lewis Corporation, and Prof. S.H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to a commercial belt filter press design that is used in many other applications. The EAD equipment is described. 2 figs.

Not Available

1989-04-18

228

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

Microsoft Academic Search

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

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

2006-01-01

229

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

230

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

Microsoft Academic Search

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

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

1998-01-01

231

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

232

Ultrafine titania by flame spray pyrolysis of a titanatrane complex  

Microsoft Academic Search

Ultrafine titania particles can be produced by flame spray pyrolysis of a chelated metal alkoxide. The precursor can be made by reacting a titanium hydrosol with triethanolamine in ethylene glycol. The chelate, dissolved in ethanol, is misted as an aerosol into an oxidizing flame where it undergoes combustion. The combustion process generates particles, probably by a gas phase condensation process,

Clint R. Bickmore; Kurt F. Waldner; Rita Baranwal; Tom Hinklin; David R. Treadwell; Richard M. Laine

1998-01-01

233

On-line analysis of the size distribution of fine and ultrafine aerosol particles in flue and stack gas of a municipal waste incineration plant: effects of dynamic process control measures and emission reduction devices.  

PubMed

The size distribution of particles in the waste gas of a municipal waste incineration plant (23 MW) was measured on-line at two sampling points in the flue-gas duct (700 and 300 degrees C) as well as in the stack gas (80 degrees C). The measurements were performed during both stable combustion conditions and transient operating conditions. The particle measurements were carried out by a mobile system consisting of a home-designed sampling system with dilution device and a scanning mobility particle sizer (SMPS) for the particle size range 17-600 nm as well as an aerodynamic particle sizer (APS) for the size range 500 nm-30 microm. The APS and SMPS data were combined using a special method and a home written software tool. The maximum of the particle-size distribution in the flue gas of the incinerator shifts from about 90 nm at the 700 degrees C sampling point to about 140 nm at the 300 degrees C point, showing the particle growth by coagulation processes and condensation of inorganic and organic gaseous species with decreasing temperature. This finding is consistent with the measured concentration profiles of gaseous organic chemical species in the flue gas. While at flue-gas temperatures of 600-800 degrees C a rich pattern of polycyclic aromatic hydrocarbon species (PAH) is observable, the PAH concentrations are considerably reduced further downstream of the flue-gas channel, where the temperature drops below 500 degrees C. Condensation and reactive bonding of gaseous chemicals onto particulate matter is, among other reasons, responsible for the depletion of gas-phase species. Process control measures, such as firing the backup burners or cleaning of the grate with pressurized air, can cause dynamic changes of the particle-size distribution. Furthermore the flue-gas cleaning measures have great impact onto both the particle concentration and the size distribution. For this reason the impact of one particular emission reduction device, the wet electrostatic dust precipitator (wet-ESP), is evaluated. The wet-ESP reduces considerably the particle concentration over the whole size range. Behind the flue-gas processing units a broad maximum in the particle-size distribution occurs at about 70 nm, but no pronounced particle-size distribution could be observed. The particle concentration level atthis maximum is about 3 magnitudes lower than in the raw flue gas. However, intermittent periods lasting for several minutes of high emissions of ultrafine particles with d < 40 nm were observed. These particles are most likely formed by nucleation processes behind the wet-ESP from gas-phase constituents of the stack gas. PMID:14594389

Maguhn, Jürgen; Karg, Erwin; Kettrup, Antonius; Zimmermann, Ralf

2003-10-15

234

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

235

Development of ultrafine multichannel microfluidic mixer for synthesis of bimetallic nanoclusters: catalytic application of highly monodisperse AuPd nanoclusters stabilized by poly(N-vinylpyrrolidone).  

PubMed

On account of their novel properties, bimetallic nanoparticles and nanoclusters (NCs) are strong potential candidates for optical, magnetic, and catalytic functional materials. These properties depend on the chemical composition and size (number of constituent atoms) of the NCs. Control of size, structure, and composition is particularly important for fabricating highly functional materials based on bimetallic NCs. Size- and structure-controlled synthesis of two-element alloys can reveal their intrinsic electronic synergistic effects. However, because synergistic enhancement of activity is strongly affected by composition as well as by size and structure, controlled synthesis is a challenging task, particularly in catalytic applications. To investigate catalytic synergistic effects, we have synthesized highly monodisperse, sub-2 nm, solid-solution AuPd NCs stabilized with poly(N-vinylpyrrolidone) (AuPd:PVP) using a newly developed ultrafine microfluidic mixing device with 15 ?m wide multiple lamination channels. The synergistic enhancement for catalytic aerobic oxidation of benzyl alcohol exhibited a volcano-shaped trend, with a maximum at 20-65 at. % Pd. From X-ray photoelectron spectroscopic measurements, we confirmed that the enhanced activity originates from the enhanced electron density at the Au sites, donated by Pd sites. PMID:25145798

Hayashi, Naoto; Sakai, Yuka; Tsunoyama, Hironori; Nakajima, Atsushi

2014-09-01

236

Low-temperature densification of ultrafine grained aluminum 6061-T6 by polymer bonding  

NASA Astrophysics Data System (ADS)

Ultrafine grained and nanocrytalline materials have many beneficial properties such as higher hardness, strength and wear resistance. A machining process has been developed as a new method to make nanostructured metals or alloys. Through the process, severe plastic deformation can be applied to metals or alloys and they become ultrafine grain and nanocrystalline in their structures. Because ultrafine grained alloys made by machining are made up to small chips, not bulk, to make bulk material, the alloy chips must be densified through processes such as sintering. Unfortunately, during the conventional sintering, the ultrafine grained alloys show grain growth at high rate and lose their hardness and strength. Therefore, low-temperature densification of ultrafine grained alloys has been pursued. In this thesis, ultrafine-grained (UFG) Al 6061-T6 particulate produced from machining chips have been consolidated and bonded using liquid epoxies that cure at 100?, below the coarsening temperature of the UFG structure. Two routes were explored---die-pressing premixed alloy particulate and epoxy and pressure infiltration of pre-pressed alloy particulate preforms. The effects of pressing pressure and epoxy viscosity were investigated. In order to reduce porosity and contamination, three treatments---application of pressure during curing of epoxy, the cleaning of the alloy powder with NaOH solution and degassing epoxy before pressing---were tried. In order to overcome limitation of diepressing, infiltration method was compared with die-pressing and the resulting properties of the composite discussed. Bond thickness between the alloy particles increases with the viscosity of the epoxies. In the hardness results by micro-indentor, the value of composite with more than 80% volume fraction of Al alloy chip (Va) was more than 120 kg/mm2. In those measurements, the hardness of the composite depends mainly on the volume fraction of Al alloy and was clearly influenced by the boundary with epoxy and porosity. In the results by macro-indentor, the hardness of composite with more than 80% Va was more than 70 kg/mm2. It was concluded that alloy volume fractions of 0.8 to 0.9 were achieved with hardness greater than that of conventional bulk al 6061-T6.

Kim, Boumseock

237

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

SciTech Connect

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

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

2007-03-15

238

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

239

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

240

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 ...

241

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 ...

242

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

243

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

244

Flow and compaction behaviour of ultrafine coated ibuprofen.  

PubMed

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

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

2013-01-30

245

The wear of ultrafine WC–Co hard metals  

Microsoft Academic Search

The wear performance of ultrafine-grained tungsten carbide–cobalt (WC–Co) hard metals during three-body abrasion and particle erosion has been evaluated and compared to that of similar conventional coarser grained hard metals. The tungsten carbide grain size varied between 0.5 and 3?m with cobalt contents ranging from 6 to 15%. Silica particles were used in both forms of testing. Erosion was carried

C. Allen; M. Sheen; J. Williams; V. A. Pugsley

2001-01-01

246

Flame pyrolysis – a preparation route for ultrafine pure ?-Fe2O3 powders and the control of their particle size and properties  

Microsoft Academic Search

Highly dispersed ?-Fe2O3 powders with particle sizes down to 5 nm were directly synthesized by combustion of solutions of\\u000a iron pentacarbonyl or iron(III) acetylacetonate in toluene in an oxyhydrogen flame. The particle size as well as other properties\\u000a of the obtained powders can be controlled simply by varying the iron concentration in the starting solutions. Phase composition,\\u000a morphological and magnetic

S. GRIMM; M SCHULTZ; S BARTH; R MULLER

1997-01-01

247

Respiratory Effects of Fine and Ultrafine Particles from Indoor Sources--A Randomized Sham-Controlled Exposure Study of Healthy Volunteers  

PubMed Central

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

2014-01-01

248

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

249

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

250

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

NASA Astrophysics Data System (ADS)

A three-dimensional regional chemical transport model (CTM) with detailed aerosol microphysics, PMCAMx-UF, was applied to the European domain to simulate the contribution of direct emissions and secondary formation to total particle number concentrations during May 2008. PMCAMx-UF uses the Dynamic Model for Aerosol Nucleation and the Two-Moment Aerosol Sectional (TOMAS) algorithm to track both aerosol number and mass concentration using a sectional approach. The model predicts nucleation events that occur over scales of hundreds up to thousands of kilometers especially over the Balkans and Southeast Europe. The model predictions were compared against measurements from 7 sites across Europe. The model reproduces more than 70% of the hourly concentrations of particles larger than 10 nm (N10) within a factor of 2. About half of these particles are predicted to originate from nucleation in the lower troposphere. Regional nucleation is predicted to increase the total particle number concentration by approximately a factor of 3. For particles larger than 100 nm the effect varies from an increase of 20% in the eastern Mediterranean to a decrease of 20% in southern Spain and Portugal resulting in a small average increase of around 1% over the whole domain. Nucleation has a significant effect in the predicted N50 levels (up to a factor of 2 increase) mainly in areas where there are condensable vapors to grow the particles to larger sizes. A semi-empirical ternary sulfuric acid-ammonia-water parameterization performs better than the activation or the kinetic parameterizations in reproducing the observations. Reducing emissions of ammonia and sulfur dioxide affects certain parts of the number size distribution.

Fountoukis, C.; Riipinen, I.; Denier van der Gon, H. A. C.; Charalampidis, P. E.; Pilinis, C.; Wiedensohler, A.; O'Dowd, C.; Putaud, J. P.; Moerman, M.; Pandis, S. N.

2012-06-01

251

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

NASA Astrophysics Data System (ADS)

A three-dimensional regional chemical transport model (CTM) with detailed aerosol microphysics, PMCAMx-UF, was applied to the European domain to simulate the contribution of direct emissions and secondary formation to total particle number concentrations during May 2008. PMCAMx-UF uses the Dynamic Model for Aerosol Nucleation and the Two-Moment Aerosol Sectional (TOMAS) algorithm to track both aerosol number and mass concentration using a sectional approach. The model predicts nucleation events that occur over scales of hundreds up to thousands of kilometers especially over the Balkans and Southeast Europe. The model predictions were compared against measurements from 7 sites across Europe. The model reproduces more than 70% of the hourly concentrations of particles larger than 10 nm (N10) within a factor of 2. About half of these particles are predicted to originate from nucleation in the lower troposphere. Regional nucleation is predicted to increase the total particle number concentration by approximately a factor of 3. For particles larger than 100 nm the effect varies from an increase of 20% in the eastern Mediterranean to a decrease of 20% in southern Spain and Portugal resulting in a small average increase of around 1% over the whole domain. Nucleation has a significant effect in the predicted N50 levels (up to a factor of 2 increase) mainly in areas where there are condensable vapors to grow the particles to larger sizes. A semi-empirical ternary sulfuric acid-ammonia-water parameterization performs better than the activation or the kinetic parameterizations in reproducing the observations. Reducing emissions of ammonia and sulfur dioxide affects certain parts of the number size distribution.

Fountoukis, C.; Riipinen, I.; Denier van der Gon, H. A. C.; Charalampidis, P. E.; Pilinis, C.; Wiedensohler, A.; O'Dowd, C.; Putaud, J. P.; Moerman, M.; Pandis, S. N.

2012-09-01

252

Effect of deformation and annealing temperatures on ultrafine microstructure development and yield strength of pearlitic steel through continuous recrystallization  

Microsoft Academic Search

Associated with the durability of railway wheels, microstructure development of high-carbon steel (0.67% C) during uniaxial compressive deformation and after subsequent annealing was studied using scanning electron microscopy and electron back scattering diffraction. The spheroidization of cementite is accelerated due to compressive deformation depending on the temperature. Annealing at 600°C leads to the formation of ferrite grain boundaries due to

Kazuyuki Handa; Yoshisato Kimura; Yuji Yasumoto; Taisuke Kamioka; Yoshinao Mishima

2010-01-01

253

Microstructure and tribo-mechanical properties of ultrafine Ti(CN) cermets  

Microsoft Academic Search

Role of Ti(CN) particle size on the microstructure of the Ti(CN)–WC–Ni cermets has been evaluated. The systems containing ultrafine grade Ti(CN) shows better structural homogeneity and a large volume fraction of rim phase in the core-rim structure when compared to the coarse Ti(CN) cermets. Measurable shift in the lattice parameter of the Ti(CN) core occurs in the ultrafine grade cermet

E. T. Jeon; J. Joardar; S. Kang

2002-01-01

254

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

255

Estimation of health risks and safety margins due to inhalation of ultrafine particles and nanoparticles in selected occupational, consumer and environmental settings  

NASA Astrophysics Data System (ADS)

Nanoparticles exhibit properties different from those of the same bulk materials leading to unknown toxicological implications that have evoked concern for (1) occupational, (2) consumer and (3) environmental safety. The current work utilizes epidemiological and toxicological data for screening level assessment of these risks using various suggested health relevant dose metrics (mass, particle number and surface area) to (i) quantify the potential risk levels and to (ii) compare the properties of these alternative risk assessment methods.

Hänninen, Otto; Brüske-Hohlfeld, Irene; Loh, Miranda; Stoeger, Tobias; Kreyling, Wolfgang; Schmid, Otmar; Peters, Annette

2009-05-01

256

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

257

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

258

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...

259

Development and scale-up of particle agglomeration processes for coal beneficiation  

NASA Astrophysics Data System (ADS)

The development of two modified agglomeration processes for coal beneficiation is presented separately in Parts I and II of this dissertation. Part I is based on research which was conducted to study the mechanism and characteristics of a gas-promoted oil agglomeration process. Part II is based on research which was carried out to develop a newer and more innovative method for agglomerating coal particles with microscopic gas bubbles in aqueous suspensions. In Part I, the development of a gas-promoted oil agglomeration process for cleaning coal was carried out with scale model mixing systems in which aqueous suspensions of ultrafine coal particles were treated with a liquid hydrocarbon and a small amount of air. The resulting agglomerates were recovered by screening. During batch agglomeration tests the progress of agglomeration was monitored by observing changes in agitator torque in the case of concentrated suspension. A key parameter turned out to be the minimum time te required to produce compact spherical agglomerates. Other important parameters included the projected area mean particle diameter of the agglomerates recovered at the end of a test as well as the ash content and yield of agglomerates. Batch agglomeration tests were conducted with geometrically similar mixing tanks which ranged in volume from 0.346 to 11.07 liters. It was shown that gas bubbles trigger the process of agglomeration and participate in a very complex mechanism involving the interaction of particles, oil droplets, and gas bubbles. The process takes place in stages involving dispersion of oil and gas, flocculation, coagulation, and agglomerate building. Numerous agglomeration tests were conducted with two kinds of coal in concentrated suspensions to determine the important characteristics of the process and to study the effects of the following operating parameters: i-octane concentration, air concentration, particle concentration, tank diameter, impeller diameter, and impeller speed. Several excellent correlations between the minimum time required to produce spherical agglomerates or a final agglomerate diameter and the operating parameters were obtained by using the general linear regression method. In addition, the results provided a basis for size scale up of an agglomeration system. In Part II, the technical feasibility of a gas agglomeration method for cleaning coal was demonstrated by means of bench-scale tests conducted with a mixing system which enabled the treatment of ultrafine coal particles with a colloidal suspension of microscopic gas bubbles in water. A suitable suspension of microbubbles was produced by agitation and a small amount of i-octane. When the suspension of microbubbles and coal particles was mixed, agglomeration was rapid and small spherical agglomerates were produced. Since the agglomerates floated, they were separated from the nonfloating tailings in a settling chamber. By employing this method in numerous agglomeration tests of moderately hydrophobic coals with 26 wt. % ash, it was shown that the ash content could be reduced to 6--7 wt. % while achieving a coal recovery of 75 to 85% on a dry, ash-free basis by using a solids concentration of 3 to 5 w/w %, air saturation of 5 to 15 psig, and i-octane concentration of 1.0 v/w % based on the coal weight. It was also shown that the process of agglomeration can be reversed by subjecting an aqueous suspension of agglomerates to a pressure sufficient to redissolve the microbubbles.

Shen, Meiyu

260

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

261

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

262

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

263

Deposition of ultrafine aerosols in rat nasal molds  

SciTech Connect

To evaluate the health effect of air pollutants on the respiratory tract, it is critical to determine the regional deposition of inhaled aerosols. Information on deposition of larger particles in the nasal passages of laboratory animals is available; the deposition fraction increases with increasing particle size. However, little deposition information is available for ultrafine particles of less than 0.2 {mu}m. Three clear, plastic molds (models) of the nasal passages of F344/N rats, prepared from metal replica casts used in these studies. Total deposition of ultrafine aerosols in the casts was determined by using a unidirectional flow system. The pressure drops measured in the casts were a function of flow rate to the power of 1.4-1.6, indicating that flow through the nasal passages has nonlaminar components. Deposition data were obtained by using monodisperse sodium chloride aerosols with particle sizes ranging from 0.2 to 0.005 {mu}m, at inspiratory and expiratory flow rates of 200 to 600 ml/min. Similar deposition data were obtained for two of the casts studied. Deposition efficiency was greatest for the smallest particles, and decreased with increasing particle size and flow rate. At an inspiratory flow rate of 400 ml/min, which is comparable to the mean respiratory flow of an adult male F344 rat with a respiratory minute volume of 200 ml, deposition efficiencies reached 40 and 70% for 0.01- and 0.005-{mu}m particles, respectively.

Cheng, Y.S.; Hansen, G.K.; Su, Y.F.; Yeh, H.C. (Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States)); Morgan, K.T. (Chemical Industry Institute of Toxicology, Research Triangle Park, NC (United States))

1990-01-01

264

Coarse(PM 2.5-10 ), Fine(PM 2.5 ), and Ultrafine Air Pollution Particles Induce\\/Increase Immune Costimulatory Receptors on Human Blood-Derived Monocytes but not on Alveolar Macrophages  

Microsoft Academic Search

Diesel particles have been shown to possess adjuvant activity and influence the development of allergic sensitization. Also, more heterogeneous mixtures of pollution particles have been shown to affect host defenses and development of immunity in animal models. In the present study it was determined whether freshly collected particulate matter (PM 10 ) in the size ranges 2.5-10 µm (PM 2.5-10

Susanne Becker; Joleen Soukup

2003-01-01

265

Improvement of characteristics of new-type solar cells, having a “transparent conductor\\/thin Si0 2 layer with ultrafine metal particles as conductive channels\\/n-Si” junction  

Microsoft Academic Search

New-type solar cells, having a structure “transparent conductor\\/thin Si02 layer with ultrafine metal islands as conductive channels\\/n-Si” have been prepared by forming a very thin (< 1.0 nm) silicon oxide (Si02) layer as well as platinum (Pt) islands (5–50 nm in size) embedded in it on a single crystal n-type silicon (n-Si) wafer, followed by the deposition of an indium

Yoshihiro Nakato; Ken-ichiro Kai; Kazuhide Kawabe

1995-01-01

266

Superior H2 production by hydrophilic ultrafine Ta2O5 engineered covalently on graphene  

NASA Astrophysics Data System (ADS)

A H2O2-mediated hydrothermal method was developed for the fabrication of hydrophilic Ta2O5/graphene composite. The composite shows a superior H2 productivity, up to 30 mmol g-1 h-1 when used as a photocatalyst for water splitting, corresponding to an apparent quantum efficiency of 33.8% at 254 nm. This superior performance is due to the hydrophilic nature of the composite and more importantly due to the ultrafine Ta2O5 nanoparticles (about 4.0 ± 1.5 nm) which are covalently bonded with the conductive graphene. The hydrophilic property of the composite is attributed to the use of H2O2 in the hydrothermal process. The ultrafine size of the Ta2O5 particles which are covalently bonded with the graphene sheets is attributed to the use of sonication in the synthesis process. Furthermore, the hydrophilic Ta2O5/Gr composite is durable, which is beneficial to long term photocatalysis. The strategy reported here provides a new approach to designing photocatalysts with superior performance for H2 production.

Mao, Lin; Zhu, Shenmin; Ma, Jun; Shi, Dian; Chen, Yixin; Chen, Zhixin; Yin, Chao; Li, Yao; Zhang, Di

2014-05-01

267

Effect of multidirectional forging and equal channel angular pressing on ultrafine grain formation in a Cu- Cr-Zr alloy  

NASA Astrophysics Data System (ADS)

The microstructure evolution was investigated in a Cu-0.3%Cr-0.5%Zr alloy subjected to large plastic deformation at temperature of 400 °C. Two methods of large plastic deformation, i.e., equal channel angular pressing (ECAP) and multidirectional forging (MDF) were used. The large plastic deformations resulted in the development of new ultrafine grains. The formation of new ultrafine grains occurred as a result of continuous reaction, i.e., progressive increase in the misorientations of deformation subboundaries. The faster kinetics of microstructure evolution was observed during MDF as compared to ECAP. The MDF to a total strain of 4 resulted in the formation of uniform ultrafine grained structure, while ECAP to the same strain led to the heterogeneous microstructure consisting of new ultrafine grains and coarse remnants of original grains. Corresponding area fractions of ultrafine grains comprised 0.23 and 0.59 in the samples subjected to ECAP and MDF, respectively.

Shakhova, I.; Belyakov, A.; Kaibyshev, R.

2014-08-01

268

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

269

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

270

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

271

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

SciTech Connect

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

Alhambra, E.M.

1994-09-01

272

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

273

High activity ultrafine Ni Co B amorphous alloy powder for the hydrogenation of benzene  

Microsoft Academic Search

An ultrafine amorphous NiCoB alloy powder, prepared by chemical reduction, showed much higher catalytic activity than Raney nickel in the hydrogenation of benzene. The only product was cyclohexane. Its amorphous structure was verified by DSC, XRD and EXAFS. TEM was used to determine its morphology. The particle size was found to be about 10 nm. The chemical composition of the

Huaiming Wang; Zhongbin Yu; Haiying Chen; Jun Yang; Jingfa Deng

1995-01-01

274

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

275

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

276

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

277

Production of Ultra-Fine Grains and Evolution of Grain Boundaries During Severe Plastic Deformation of Aluminum and its Alloys.  

National Technical Information Service (NTIS)

Equal channel-angular pressing (ECAP) is a recently developed method for deformation processing of material that can produce an ultra-fine grain structure in bulk material through severe plastic deformation. This study will present results on micro struct...

D. L. Swisher

2000-01-01

278

Development of a particle nanoimprinting technique by core-shell particles.  

PubMed

We developed a particle nanoimprinting technique assisted by the array of core-shell particles. Core-shell particles composed of a solid core of polystyrene and a soft shell were prepared by soap-free emulsion polymerization and subsequently seeded polymerization. By the Langmuir-Blodgett method, particles were arranged into a closely packed 2D array over the water surface and transferred onto a polystyrene (PS) substrate at a regular interval. The PS substrate was heated up above its glass transition temperature (Tg) by either UV irradiation using a high-pressure Hg lamp or heat treatment in a temperature-controlled incubator. It could be observed that a nanopatterned indented surface was formed through the denting of particles into the PS substrate (particle nanoindenting). By the detachment of particles from the substrate by ultrasonication in ethanol, nanoholes were produced over the surface (particle nanoimprinting). The depth and the wall of nanoholes and their interval were tunable by the shell thickness and the 2D packing ratio of core-shell particle monolayers. The contact angle decreased from 70 degrees of the pristine particle monolayer to 13 degrees by the particle nanoindenting, and again increased to 50 degrees by detaching the particles from the substrate to create the nanoholes. The use of nanoholes as zepto-litter volume vessels enabled us to produce and arrange nanocrystals, such as NaCl and CaCO3 (zepto-reactor). PMID:24446687

Watanabe, H; Nishimura, M; Fukui, Y; Fujimoto, K

2014-02-18

279

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

Microsoft Academic Search

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

Frank Collins; J. G Sanjayan

1999-01-01

280

New particle formation observed in the tropical\\/subtropical cirrus clouds  

Microsoft Academic Search

Previous studies show that new particle formation takes place in the outflows of marine stratus and cumulus clouds. Here we show measurements of high concentrations of ultrafine particles, diameters (Dp) from 4 to 9 nm (N4–9), in interstitial cloud aerosol. These ultrafine particles indicate that in situ new particle formation occurs interstitially in cirrus clouds. Measurements were made at altitudes

S.-H. Lee; J. C. Wilson; D. Baumgardner; R. L. Herman; E. M. Weinstock; B. G. LaFleur; G. Kok; B. Anderson; P. Lawson; B. Baker; A. Strawa; J. V. Pittman; J. M. Reeves; T. P. Bui

2004-01-01

281

New particle formation observed in the tropical\\/subtropical cirrus clouds  

Microsoft Academic Search

Previous studies show that new particle formation takes place in the outflows of marine stratus and cumulus clouds. Here we show measurements of high concentrations of ultrafine particles, diameters (Dp) from 4 to 9 nm (N4-9), in interstitial cloud aerosol. These ultrafine particles indicate that in situ new particle formation occurs interstitially in cirrus clouds. Measurements were made at altitudes

S.-H. Lee; J. C. Wilson; D. Baumgardner; R. L. Herman; E. M. Weinstock; B. G. LaFleur; G. Kok; B. Anderson; P. Lawson; B. Baker; A. Strawa; J. V. Pittman; J. M. Reeves; T. P. Bui

2004-01-01

282

Ultrafine spinel powders by flame spray pyrolysis of a magnesium aluminum double alkoxide  

Microsoft Academic Search

Ultrafine crystalline spinel powder has been prepared using flame spray pyrolysis of alcoholic solutions of a novel double alkoxide precursor. The particles produced are spherical, dense, single crystals with diameters of 10--100 nm and specific surface areas ranging from 40 to 60 m²\\/g. Powder production rates of 50--100 g\\/h are achieved using a bench-top apparatus. Particle formation appears to occur

Clint R. Bickmore; Kurt F. Waldner; David R. Treadwell; Richard M. Laine

1996-01-01

283

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

284

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

285

Current Development Status of a Particle Size Analyzer for Coated Particle Fuel  

SciTech Connect

Work was performed to develop a prototype Particle Size Analyzer (PSA) for application to coated particle fuel characterization. This system was based on a light obscuration method and targeted towards high throughput analysis. Although never matured to the point of replacing existing lower throughput optical microscopy shadowgraph methods, the system was successfully applied to automating the counting of large particle samples for increased accuracy in calculating mean particle properties based on measurements of multiparticle samples. The measurement of particle size with the PSA was compared to current shadowgraph techniques and found to result in considerably greater throughput at the cost of larger measurement uncertainty. The current algorithm used by the PSA is more sensitive to particle shape and this is a likely cause of the greater uncertainty when attempting to measure average particle diameter. The use of the PSA to measure particle shape will require further development. Particle transport through the PSA and stability of the light source/detector are key elements in the successful application of this technique. A number of system pitfalls were studied and addressed.

Nelson, Andrew T [ORNL; Hunn, John D [ORNL; Karnowski, Thomas Paul [ORNL

2007-08-01

286

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

Microsoft Academic Search

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

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

2010-01-01

287

Particle and Wave: Developing the Quantum Wave Accompanying a Classical Particle  

E-print Network

The relationship between classical and quantum mechanics is explored in an intuitive manner by the exercise of constructing a wave in association with a classical particle. Using special relativity, the time coordinate in the frame of reference of a moving particle is expressed in terms of the coordinates in the laboratory frame of reference in order to provide an initial spatiotemporal function to work from in initiating the development of a quantum wave. When temporal periodicity is ascribed to the particle, a provisional spatiotemporal function for a particle travelling at constant velocity manifests itself as an running wave characterized by parameters associated with the moving particle. A wave description for bidirectional motion is generated based on an average time coordinate for a combination of oppositely directed elementary running waves, and the resulting spatiotemporal function exhibits wave behavior characteristic of a standing wave. Ascribing directional orientation to the intrinsic periodicity of the particle introduces directional sub-states; variations in the relative number of sub-states as a function of angle in combined states lead to spatially varying magnitudes for the associated waves. Further analysis leads to full mathematical expression for all waves representing free particle motion. A generalization for particles subject to force fields enables us to develop a governing differential equation identical in form to the Schroedinger equation.

C. L. Herzenberg

2008-12-04

288

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

289

Synthesis of ultrafine powders by microwave heating  

DOEpatents

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

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

1988-01-01

290

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, Jurgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem

2014-01-01

291

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

292

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

293

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

294

Development of HTGR-coated particle fuel technology in Korea  

Microsoft Academic Search

The status of R&D works being carried out for the development of the technology for the coated fuel particles and the achievements in the first phase in Korea is described. Emphasis is given to the development of the laboratory equipment and apparatus and the first results of the experiments carried out for the kernel preparation and coating of PyC and

Young-Woo Lee; Ji-Yeon Park; Yeon Ku Kim; Kyung Chae Jeong; Woong Ki Kim; Bong Goo Kim; Young Min Kim; Moon Sung Cho

2008-01-01

295

Common mode choke cores using the new Fe-based alloys composed of ultrafine grain structure  

Microsoft Academic Search

Common mode choke cores using the new Fe-based alloys called ‘‘FINEMET’’ composed of ultrafine grain structure were developed. These new cores show high attenuation to high-voltage pulse noises and good attenuation characteristics over a wide frequency range. Accordingly, the new cores are expected to be applied in many applications as line filters for electronic devices.

Y. Yoshizawa; K. Yamauchi; T. Yamane; H. Sugihara

1988-01-01

296

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

297

Investigation of the structural–phase state of ultrafine plasmochemical ZrO2 (Y) powders  

NASA Astrophysics Data System (ADS)

The methods of X–ray phase analysis, thermogravimetry and differential scanning calorimetry were used to study the structural and phase state of ultrafine powders (UFP) of ZrO2(Y) obtained by plasmochemical synthesis. It is shown that these UFPs are in a highly nonequilibrium state due to the presence of adsorbates and bound water, and the distribution of the stabilizing impurity in the volume of the particles is nonuniform.

Ghyngazov, S. A.; Vasiliev, I. P.; Frangulyan, T. S.; Khaidukova, V. M.; Mylnikova, T. S.

2014-10-01

298

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

Microsoft Academic Search

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

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

2000-01-01

299

Development of particle standards for testing explosive detection systems: characterization of the adhesion forces between composition 4 particles and polyethylene  

Microsoft Academic Search

A method has been developed to study the adhesion of particles on a surface and the gas velocity needed to overcome the adhesion and dislodge the particle from the surface. Experiments have been performed to determine the minimum detachment velocity for particles deposited on a surface by gravitational settling and by finger print transfer. Particles of Arizona road dust and

Benjamin Y. Liu; S. H. Yoo; John P. Davies; Garold L. Gresham; Susan F. Hallowell

1994-01-01

300

Enhanced strength and electrical conductivity in ultrafine-grained Cu-Cr alloy processed by severe plastic deformation  

NASA Astrophysics Data System (ADS)

The influence of severe plastic deformation on strength and electrical conductivity in the Cu-Cr copper alloy has been studied. Microstructure of ultrafine-grained samples was investigated by transmission electron microscopy and X-ray diffraction with special attention on precipitation of small chromium particles after various thermal treatments. Effect of dynamic precipitation leading to enhancement of strength and electrical conductivity was observed. It is shown that ultrafine-grained samples enable to demonstrate the combination of enhanced thermal stability up to 500°C, high ultimate tensile strength of 790-840 MPa and enhanced electrical conductivity of 81-85% IACS. The contributions of grain boundaries and precipitates to enhanced properties of ultrafine-grained copper alloy are discussed.

Islamgaliev, R. K.; Nesterov, K. M.; Champion, Y.; Valiev, R. Z.

2014-08-01

301

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

302

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

303

Mechanisms involved in ultrafine carbon black-induced release of IL-6 from primary rat epithelial lung cells.  

PubMed

The aims of the present study were to establish to what extent IL-1, and intracellular pathways involving mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-kappaB), play a role in ultrafine particle-induced release of IL-6 by primary rat epithelial lung cells. Ultrafine carbon black (Printex 90) induced a concentration- and time-dependent increase in the release of IL-1alpha, IL-1beta and IL-6. The ultrafine carbon black-induced release of IL-6 was completely eliminated by an IL-1 receptor antagonist (IL-1ra). Cellular release of IL-1alpha, IL-1beta and IL-6 was significantly attenuated by curcumin and by inhibitors of the MAPKs ERK1/2 (PD98069), p38 (SB202190) and JNK (SP600125), whereas pyrrolidine dithiocarbamate (PDTC) attenuated the release of IL-6, but not of IL-1alpha and IL-1beta. The effects of curcumin and PDTC may indicate an involvement of NF-kappaB. Furthermore, ultrafine carbon black induced degradation of IkappaBalpha, used as an indicator of NF-kappaB activation, and induced phosphorylation of ERK1/2, p38 and JNK1/2. This degradation and phosphorylation was attenuated by IL-1ra. The present findings provide more insight into the largely unknown mechanisms involved in ultrafine particle-induced release of cytokines from lung cells. The findings suggest that ultrafine carbon black-induced release of IL-6 strongly depends on IL-1 and that activation of MAPKs and NF-kappaB is involved in this response. PMID:19782127

Totlandsdal, Annike I; Refsnes, Magne; Låg, Marit

2010-02-01

304

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

305

HEASD PM RESEARCH METHODS: PARTICLE METHODS EVALUATION AND DEVELOPMENT  

EPA Science Inventory

The FRM developed by NERL forms the backbone of the EPA's national monitoring strategy. It is the measurement that defines attainment of the new standard. However, the agency has numerous other needs in assessing the physical and chemical characteristics of ambient fine particl...

306

Experimental Investigation of Magnesium-Base Nanocomposite Produced by Friction Stir Processing: Effects of Particle Types and Number of Friction Stir Processing Passes  

Microsoft Academic Search

In this research, nanosized SiC and Al2O3 particles were added to as-cast AZ91 magnesium alloy, and surface nanocomposite layers with ultrafine-grained structure were\\u000a produced via friction stir processing (FSP). Effects of reinforcing particle types and FSP pass number on the powder distribution pattern,\\u000a microstructure, microhardness, and on tensile and wear properties of the developed surfaces were investigated. Results show\\u000a that

P. Asadi; G. Faraji; A. Masoumi; M. K. Besharati Givi

2011-01-01

307

Primitive ultrafine matrix in ordinary chondrites  

NASA Astrophysics Data System (ADS)

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.

1981-12-01

308

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

309

In vivo deposition of ultrafine aerosols in the nasal airway of the rat  

SciTech Connect

We studied the deposition of ultrafine aerosols, ranging in geometric diameter from 0.005 to 0.1 microns, in the nasal airway of Fischer-344/N rats, at inspiratory flow rates of 200, 300, 400, and 600 ml/min. Simultaneously, we measured the pressure drop across the rat nasal airway. The purpose was to determine whether the in vivo deposition of ultrafine aerosols in the rat nasal airway is the same as the deposition observed in rat nasal casts. At a flow rate of 400 ml/min, corresponding to the normal mean inspiratory flow rate of the rat, deposition efficiency increased from 6 to 58%, when the particle diameter decreased from 0.1 to 0.005 microns. For 0.005-microns-diameter particles, the deposition efficiency decreased from 68 to 52% when the flow rate was increased from 200 to 600 ml/min. These results agree well with those from previous experiments with nasal casts, which indicated that diffusion is the dominant mechanism for deposition of ultrafine aerosols. The pressure drop in the nasal airway of the rat increased almost linearly with flow rate, from 73 Pa at 200 ml/min to 247 Pa at 600 ml/min. These values are within the range of those obtained in previous experiments with nasal casts, although the pressure drop in casts increased as a power greater than 1 with flow rate. The results of our study support the use of nasal airway casts to estimate the in vivo deposition of ultrafine aerosols.

Gerde, P.; Cheng, Y.S.; Medinsky, M.A. (Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (USA))

1991-02-01

310

Daily trends and source apportionment of ultrafine particulate mass (PM0.1) over an annual cycle in a typical California city.  

PubMed

Toxicology studies indicate that inhalation of ultrafine particles (Dp < 0.1 ?m) causes adverse health effects, presumably due to their large surface area-to-volume ratio that can drive heterogeneous reactions. Epidemiological associations between ultrafine particles and health effects, however, have been difficult to identify due to the lack of appropriate long-term monitoring and exposure data. The majority of the existing ultrafine particle epidemiology studies are based on exposure to particle number, although an independent analysis suggests that ultrafine particle mass (PM0.1) correlates better with particle surface area. More information is needed to characterize PM0.1 exposure to fully evaluate the health effects of ultrafine particles using epidemiology. The present study summarizes 1 year of daily PM0.1 chemistry and source apportionment at Sacramento, CA, USA. Positive matrix factorization (PMF) was used to resolve PM0.1 source contributions from old-technology diesel engines, residential wood burning, rail, regional traffic, and brake wear/road dust. Diesel PM0.1 and total PM0.1 concentrations were reduced by 97 and 26%, respectively, as a result of the adoption of cleaner diesel technology. The strong linear correlation between PM0.1 and particle surface area in central California suggests that the adoption of clean diesel engines reduced particle surface area by similar amounts. PM0.1 sulfate reduction occurred as a result of reduced primary particle surface area available for sulfate condensation. The current study demonstrates the capability of measuring PM0.1 source contributions over a 12 month period and identifies the extended benefits of emissions reduction efforts for diesel engines on ambient concentrations of primary and secondary PM0.1. PMID:24245739

Kuwayama, Toshihiro; Ruehl, Chris R; Kleeman, Michael J

2013-12-17

311

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

312

Age-specific effects on rat lung glutathione and antioxidant enzymes after inhaling ultrafine soot.  

PubMed

Vehicle exhaust is rich in polycyclic aromatic hydrocarbons (PAHs) and is a dominant contributor to urban particulate pollution (PM). Exposure to PM is linked to respiratory and cardiovascular morbidity and mortality in susceptible populations, such as children. PM can contribute to the development and exacerbation of asthma, and this is thought to occur because of the presence of electrophiles in PM or through electrophile generation via the metabolism of PAHs. Glutathione (GSH), an abundant intracellular antioxidant, confers cytoprotection through conjugation of electrophiles and reduction of reactive oxygen species. GSH-dependent phase II detoxifying enzymes glutathione peroxidase and glutathione S-transferase facilitate metabolism and conjugation, respectively. Ambient particulates are highly variable in composition, which complicates systematic study. In response, we have developed a replicable ultrafine premixed flame particle (PFP)-generating system for in vivo studies. To determine particle effects in the developing lung, 7-day-old neonatal and adult rats inhaled 22 ?g/m(3) PFP during a single 6-hour exposure. Pulmonary GSH and related phase II detoxifying gene and protein expression were evaluated 2, 24, and 48 hours after exposure. Neonates exhibited significant depletion of GSH despite higher initial baseline levels of GSH. Furthermore, we observed attenuated induction of phase II enzymes (glutamate cysteine ligase, glutathione reductase, glutathione S-transferase, and glutathione peroxidase) in neonates compared with adult rats. We conclude that developing neonates have a limited ability to deviate from their normal developmental pattern that precludes adequate adaptation to environmental pollutants, which results in enhanced cytotoxicity from inhaled PM. PMID:23065132

Chan, Jackie K W; Kodani, Sean D; Charrier, Jessie G; Morin, Dexter; Edwards, Patricia C; Anderson, Donald S; Anastasio, Cort; Van Winkle, Laura S

2013-01-01

313

Age-Specific Effects on Rat Lung Glutathione and Antioxidant Enzymes after Inhaling Ultrafine Soot  

PubMed Central

Vehicle exhaust is rich in polycyclic aromatic hydrocarbons (PAHs) and is a dominant contributor to urban particulate pollution (PM). Exposure to PM is linked to respiratory and cardiovascular morbidity and mortality in susceptible populations, such as children. PM can contribute to the development and exacerbation of asthma, and this is thought to occur because of the presence of electrophiles in PM or through electrophile generation via the metabolism of PAHs. Glutathione (GSH), an abundant intracellular antioxidant, confers cytoprotection through conjugation of electrophiles and reduction of reactive oxygen species. GSH-dependent phase II detoxifying enzymes glutathione peroxidase and glutathione S-transferase facilitate metabolism and conjugation, respectively. Ambient particulates are highly variable in composition, which complicates systematic study. In response, we have developed a replicable ultrafine premixed flame particle (PFP)-generating system for in vivo studies. To determine particle effects in the developing lung, 7–day-old neonatal and adult rats inhaled 22 ?g/m3 PFP during a single 6-hour exposure. Pulmonary GSH and related phase II detoxifying gene and protein expression were evaluated 2, 24, and 48 hours after exposure. Neonates exhibited significant depletion of GSH despite higher initial baseline levels of GSH. Furthermore, we observed attenuated induction of phase II enzymes (glutamate cysteine ligase, glutathione reductase, glutathione S-transferase, and glutathione peroxidase) in neonates compared with adult rats. We conclude that developing neonates have a limited ability to deviate from their normal developmental pattern that precludes adequate adaptation to environmental pollutants, which results in enhanced cytotoxicity from inhaled PM. PMID:23065132

Chan, Jackie K. W.; Kodani, Sean D.; Charrier, Jessie G.; Morin, Dexter; Edwards, Patricia C.; Anderson, Donald S.; Anastasio, Cort

2013-01-01

314

Ultrafine spinel powders by flame spray pyrolysis of a magnesium aluminum double alkoxide  

SciTech Connect

Ultrafine crystalline spinel powder has been prepared using flame spray pyrolysis of alcoholic solutions of a novel double alkoxide precursor. The particles produced are spherical, dense, single crystals with diameters of 10--100 nm and specific surface areas ranging from 40 to 60 m{sup 2}/g. Powder production rates of 50--100 g/h are achieved using a bench-top apparatus. Particle formation appears to occur by rapid oxidation of the organic ligands followed by nucleation and growth from oxide species.

Bickmore, C.R.; Waldner, K.F.; Treadwell, D.R.; Laine, R.M. [Univ. of Michigan, Ann Arbor, MI (United States)

1996-05-01

315

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

316

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

317

Meteorological influences on particle growth events in Beltsville, MD during July 2011  

NASA Astrophysics Data System (ADS)

During summer 2011, particle growth events were investigated in Beltsville, MD, USA where anthropogenic and biogenic hydrocarbon emissions heavily influence the atmosphere. Ultrafine particle growth events were studied during this period and occurred on cooler (temperature 8°C less), drier (relative humidity 19% less), and clearer days than on the average July 2011 non-growth event day. These events occurred after cold air advection associated with cold frontal passages with significant precipitation. This dataset showed two interested types of cases: elevated ultrafine (<25 nm) number concentrations during the night-time hours (01 - 11 Universal Time Coordinated, UTC) and regional particle growth events during the day-time hours (11 - 00 UTC). At night, local sources of ammonium nitrate particles are present during low frictional velocities, high relative humidity, and lower temperatures. These events occurred throughout the campaign regardless of frontal passage and showed evidence of nucleating particles, growing to 30 nm. During the day, regional particle growth events grew to sizes around 110 nm at an average growth rate of 3.5 nm hr-1. These results show that regional particle growth events occur shortly after an increase in turbulent mixing, an increase in temperature and a decrease in relative humidity, all consistent with the expansion of the boundary layer due to diurnal heating. Increased concentrations of sulfur dioxide (SO2) occurred just prior to the particle growth events being detected at 15:00 UTC. The peak in SO2 coincided with the breakdown of the nocturnal boundary layer and when the convective boundary layer began developing. More investigations using photochemical box-models will be presented to determine the significance of these chemical species on the elevated night-time ultrafine particles (ammonium nitrate) and regional particle growth events (SO2).

Payne, M. K.; Joseph, E.; Sakai, R. K.; Fuentes, J. D.; Stockwell, W. R.

2013-12-01

318

Grain Boundaries and Mechanical Properties of Ultrafine-Grained Metals  

NASA Astrophysics Data System (ADS)

The concept of grain boundary (GB) engineering of ultrafine-grained (UFG) metals and alloys is developed for enhancement of their properties by tailoring different GBs (low-angle and high-angle ones, special and random, or equilibrium and nonequilibrium) and formation of GB segregations and precipitations by severe plastic deformation (SPD) processing. In this article, using this approach and varying regimes and routes of SPD processing, we show for several light alloys (Al and Ti) the ability to produce UFG materials with different GBs, and this can have a dramatic effect on the mechanical behavior of the processed materials. This article demonstrates also several new examples of attaining superior strength and ductility as well as enhanced superplasticity at low temperatures and high strain rates in various UFG metals and alloys.

Valiev, Ruslan Z.; Murashkin, Maxim Yu.; Semenova, Irina P.

2010-04-01

319

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

PubMed

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

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

2011-12-01

320

Real-time prediction of size-resolved ultrafine particulate matter on freeways.  

PubMed

Ultrafine particulate matter (UFP; diameter <0.1 ?m) concentrations are relatively high on the freeway, and time spent on freeways can contribute a significant fraction of total daily UFP exposure. We model real-time size-resolved UFP concentrations in summer time on-freeway air. Particle concentrations (32 bins, 5.5 to 600 nm) were measured on Minnesota freeways during summer 2006 and 2007 ( Johnson, J. P.; Kittelson, D. B.; Watts, W. F. Environ. Sci. Technol. 2009 , 43 , 5358 - 5364 ). Here, we develop and apply two-way stratified multilinear regressions, using an approach analogous to mobile-monitoring land-use regression but using real-time meteorological and traffic data. Our models offer the strongest predictions in the 10-100 nm size range (adj-R(2): 0.79-0.89, average adj-R(2): 0.85) and acceptable but weaker predictions in the 130-200 nm range (adj-R(2): 0.41-0.62, average adj-R(2): 0.52). The aggregate model for total particle counts performs well (adj-R(2) = 0.77). Bootstrap resampling (n = 1000) indicates that the proposed models are robust to minor perturbations in input data. The proposed models are based on readily available real-time information (traffic and meteorological parameters) and can thus be exploited to offer spatiotemporally resolved prediction of UFPs on freeways within similar geographic and meteorological environments. The approach developed here provides an important step toward modeling population exposure to UFP. PMID:22185611

Aggarwal, Srijan; Jain, Ricky; Marshall, Julian D

2012-02-21

321

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

322

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

323

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

324

Developments in time analysis of particle and photon tunnelling  

E-print Network

A compact analysis of development and prospects in the study of the tunnelling evolution is given. A new systematization of various approaches to defining tunnelling times in the light of time as a quantum mechanical observable is proposed. The problem of superluminal group velocities, without violations of special relativity, is also taken in account. Then a particular attention is devoted to the presentation of new results on the analogy between particle and photon tunnelling and analysis of the causality validity during tunnelling. [PACS nos. 03.40.Kf, 03.50.De, 41.20.Jb, 41.20.Bt, 42.25.Bs, 03.30.+p, 03.65.-w].

V. S. Olkhovsky; A. Agresti

1996-12-06

325

Ultrafine Grain Formation in Ferritic Stainless Steel during Severe Plastic Deformation  

NASA Astrophysics Data System (ADS)

The development of submicrocrystalline structures in Fe-20 pct Cr ferritic stainless steel was studied in multidirectional forging to large total strains. The structural changes are characterized by the development of microshear bands in high density dislocation substructures. The multidirectional deformation promotes the multiple shearing, which results in the formation of a spatial net of mutually crossed microshear bands subdividing the original grains. The new grains with high-angle boundaries appear primarily at the microshear band intersections and subsequently along the bands. The fraction of ultrafine grains gradually increases with increasing the density of microshear bands as a result of continuous increase in misorientations among deformation subgrains during processing. An increase in the processing temperature can accelerate remarkably the kinetics of ultrafine grain evolution at large strains. The mechanism of strain-induced grain formation is discussed in detail.

Sakai, T.; Belyakov, A.; Miura, H.

2008-09-01

326

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

327

LIGHT MICROSCOPY DETECTION OF NANOSCALE PARTICLE INTERNALIZATION BY HUMAN LUNG CELLS  

EPA Science Inventory

RATIONALE. Ultrafine particulate matter (PM) is reported to be more strongly correlated with adverse health effects relative to larger particle size fractions. These epidemiological findings are supported by toxicological studies suggesting that particle size is inversely associa...

328

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

329

Development of Pressure sensing Particles through SERS and Upconversion  

NASA Astrophysics Data System (ADS)

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

Widejko, Ryan; Wang, Fenglin; Anker, Jeff

2012-03-01

330

Preparation of spherical ultrafine copper powder via hydrogen reduction-densification of Mg(OH)2-coated Cu2O powder  

NASA Astrophysics Data System (ADS)

A novel process was developed to produce spherical copper powder for multilayer ceramic capacitors (MLCC). Spherical ultrafine cuprous oxide (Cu2O) powder was prepared by glucose reduction of Cu(OH)2. The Cu2O particles were coated by Mg(OH)2 and reduced to metallic copper particles. At last, the copper particles were densified by high-temperature heat treatment. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), tap density, and thermogravimetry (TG). It is found that the shape and size distribution of the copper powder are determined by the Cu2O powder and the copper particles do not agglomerate during high-temperature heat treatment because of the existence of Mg(OH)2 coating. After densification at high temperature, the particle tap density increases from 3.30 to 4.18 g/cm3 and the initial oxidation temperature rises from 125 to 150°C.

Wang, Yue-jun; Zhou, Kang-gen

2012-11-01

331

Water-stable three-dimensional ultrafine fibrous scaffolds from keratin for cartilage tissue engineering.  

PubMed

Intrinsically water-stable scaffolds composed of ultrafine keratin fibers oriented randomly and evenly in three dimensions were electrospun for cartilage tissue engineering. Keratin has been recognized as a biomaterial that could substantially support the growth and development of multiple cell lines. Besides, three-dimensional (3D) ultrafine fibrous structures were preferred in tissue engineering due to their structural similarity to native extracellular matrices in soft tissues. Recently, we have developed a nontraditional approach to developing 3D fibrous scaffolds from alcohol-soluble corn protein, zein, and verified their structural advantages in tissue engineering. However, keratin with highly cross-linked molecular structures could not be readily dissolved in common solvents for fiber spinning, which required the remarkable drawability of solution. So far, 3D fibrous scaffolds from pure keratin for biomedical applications have not been reported. In this research, the highly cross-linked keratin from chicken feathers was de-cross-linked and disentangled into linear and aligned molecules with preserved molecular weights, forming highly stretchable spinning dope. The solution was readily electrospun into scaffolds with ultrafine keratin fibers oriented randomly in three dimensions. Due to the highly cross-linked molecular structures, keratin scaffolds showed intrinsic water stability. Adipose-derived mesenchymal stem cells could penetrate much deeper, proliferate, and chondrogenically differentiate remarkably better on the 3D keratin scaffolds than on 2D PLA fibrous scaffolds, 3D soy protein fibrous scaffolds, or 3D commercial nonfibrous scaffolds. In summary, the electrospun 3D ultrafine fibrous scaffolds from keratin could be promising candidates for cartilage tissue engineering. PMID:25010870

Xu, Helan; Cai, Shaobo; Xu, Lan; Yang, Yiqi

2014-07-22

332

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

333

Study on ultra-fine w-EDM with on-machine measurement-assisted  

SciTech Connect

The purpose of this study was to develop the on-machine measurement techniques so as to precisely fabricate micro intricate part using ultra-fine w-EDM. The measurement-assisted approach which employs an automatic optical inspection (AOI) is incorporated to ultra-fine w-EDM process to on-machine detect the machining error for next re-machining. The AOI acquires the image through a high resolution CCD device from the contour of the workpiece after roughing in order to further process and recognize the image for determining the residual. This facilitates the on-machine error detection and compensation re-machining. The micro workpiece and electrode are not repositioned during machining. A fabrication for a micro probe of 30-{mu}m diameter is rapidly machined and verified successfully. Based on the proposed technique, on-machine measurement with AOI has been realized satisfactorily.

Chen Shuntong [Department of Mechatronic Technology, National Taiwan Normal University (China); Yang Hongye [Department of Industrial Education, National Taiwan Normal University (China)

2011-01-17

334

Pseudophasic extraction method for the separation of ultra-fine minerals  

DOEpatents

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

Chaiko, David J. (Naperville, IL)

2002-01-01

335

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

336

Ultrafine fibrous gelatin scaffolds with deep cell infiltration mimicking 3D ECMs for soft tissue repair.  

PubMed

In this research, ultrafine fibrous scaffolds with deep cell infiltration and sufficient water stability have been developed from gelatin, aiming to mimic the extracellular matrices (ECMs) as three dimensional (3D) stromas for soft tissue repair. The ultrafine fibrous scaffolds produced from the current technologies of electrospinning and phase separation are either lack of 3D oriented fibrous structure or too compact to be penetrated by cells. Whilst electrospun scaffolds are able to emulate two dimensional (2D) ECMs, they cannot mimic the 3D ECM stroma. In this work, ultralow concentration phase separation (ULCPS) has been developed to fabricate gelatin scaffolds with 3D randomly oriented ultrafine fibers and loose structures. Besides, a non-toxic citric acid crosslinking system has been established for the ULCPS method. This system could endow the scaffolds with sufficient water stability, while maintain the fibrous structures of scaffolds. Comparing with electrospun scaffolds, the ULCPS scaffolds showed improved cytocompatibility and more importantly, cell infiltration. This research has proved the possibility of using gelatin ULCPS scaffolds as the substitutes of 3D ECMs. PMID:24728742

Jiang, Qiuran; Xu, Helan; Cai, Shaobo; Yang, Yiqi

2014-07-01

337

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

338

Ultrafine Particulate Dispersed High-Temperature Coatings by Hybrid Spray Process  

NASA Astrophysics Data System (ADS)

Oxide dispersion strengthened alloys (ODS), although not commonly used in coating applications, have long been used for high-temperature structural applications due to their superior creep properties. In this paper, we present the design, synthesis, and characterization of a new class of functionally engineered high-temperature coatings in which ultrafine oxide particulates are dispersed in the matrix alloy to achieve superior creep resistance along with improved high-temperature corrosion and erosion resistance. These coatings were fabricated using a novel technique called “hybrid spray process”. Hybrid spray technique combines arc spray and high-velocity oxy fuel (HVOF) spray processes; the metallic matrix alloys are fused by the wire arcing component of the process, whereas the ultrafine particles are synthesized in-flight by the HVOF component from liquid precursors. These particulate dispersed high-temperature composite coatings were fabricated using liquid precursors for SiO2, Cr2O3, Al2O3, and wire feed stock of 55/45 NiCr, in one step. The coatings were then characterized using electron microscopy (SEM/TEM) and thermogravimetric analysis (TGA). High-temperature erosion, oxidation, and corrosion performance of these coatings were also evaluated and compared with 304 stainless steel, arc sprayed NiCr coatings as well as Alloy 625 overlay cladding. The hybrid spray process produced dense coatings with uniform dispersion of the ultrafine oxide particles. Further, these coatings also demonstrated superior corrosion, erosion, and oxidation resistance; SiO2 particulate dispersion being most effective in terms of high-temperature corrosion resistance.

Mohanty, P. S.; Roche, A. D.; Guduru, R. K.; Varadaraajan, V.

2010-01-01

339

DEVELOPMENT OF AN INTEGRATED PERFORMANCE MODEL FOR TRISO-COATED GAS REACTOR PARTICLE FUEL  

Microsoft Academic Search

The success of gas reactors depends upon the safety and quality of the coated particle fuel. The understanding and evaluation of this fuel requires development of an integrated mechanistic fuel performance model that fully describes the mechanical and physico- chemical behavior of the fuel particle under irradiation. Such a model, called PARFUME (PARticle FUel ModEl), is being developed at the

G. K. MILLER; D. A. PETTI; J. T. MAKI

340

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

341

SYSTEMIC INTERACTIONS BETWEEN INHALED ULTRAFINE PARTICLES AND ENDOTOXIN. (R826784)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

342

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

343

Number concentration and chemical composition of ultrafine and nanoparticles from WTE (waste to energy) plants.  

PubMed

Stack field testing at four municipal waste-to-energy (WTE) plants was conducted to investigate total number concentrations and size distributions in a size range extended towards the evaluation of ultrafine (UFP) and nanoparticle (NP) fractions with diameters smaller than 100nm and 50nm, respectively. Measurements were performed with a specifically designed sampling line, equipped with a dilution system and a particle counting device for measuring both primary particles in raw flue gases at stack conditions and the contributions of condensable origin, arising from their cooling and dilution immediately following stack release into the atmosphere. Average concentration levels detected ranged between 5×10(3)-6×10(5)cm(-3): for all sampling conditions, ultrafine fractions largely prevailed in number size distributions, with average diameters constantly located in the nanoparticle size range. Stack concentrations appeared to be influenced by the design and process configuration of flue gas cleaning systems, with most significant effects related to the presence of wet scrubbing units and the baghouse operating temperature of dry removal processes. Chemical speciation (i.e., trace metals, anions and cations, carbonaceous compounds) of size-resolved particulate fractions was performed on one of the plants. NP and UFP composition was essentially in accordance with the most important fuel and combustion process characteristics: in particular, the presence of chlorides and metal species was consistent with the respective waste feed content and their expected behavior during combustion and flue gas cleaning processes. PMID:22326138

Cernuschi, Stefano; Giugliano, Michele; Ozgen, Senem; Consonni, Stefano

2012-03-15

344

Mammalian cell-transforming potential of traffic-linked ultrafine particulate matter PM0.056 in urban roadside atmosphere.  

PubMed

We examined the clastogenic and cell-transforming potential of ultrafine particulate matter fraction PM0.056 of urban ambient aerosol using mammalian cells. PM1.0, PM0.56 and PM0.056 fractions were sampled from roadside atmosphere of an urban area using the cascade impactor MOUDI-NR-110. The potential to induce cytotoxicity, DNA damage and micronuclei formation was examined at the test concentrations of 3, 6, 12.5, 25, 50 and 100 ?g/ml using the 3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, the plasmid relaxation assay and the C3H10T1/2 (10T1/2) cells. The cell-transforming potential was investigated in vitro using 10T1/2 cell transformation assay and the soft agar assay. PM1, PM0.56 and PM0.056 fractions were found to be toxic in dose-dependent manner. These induced cytotoxicity at five test concentrations, the ultrafine particle fraction PM0.056 showed greater cytotoxic potential. PM0.056 induced micronucleus formation in 10T1/2 cells. The effect was statistically significant. The DNA-damaging potential was measured in a plasmid relaxation assay. Both fine and ultrafine particle fraction PM0.56 and PM0.056 displayed greater effect as compared to larger PM1 fraction. DNA damage was found to be dependent on particulate matter intrinsic pro-oxidant chemicals. The ability of the ultrafine particle fraction PM0.056 to induce morphological cell transformation was demonstrated by significant and dose-dependent increases in type III focus formation by morphologically transformed cells in culture flasks and their clonal expansion in soft agar. It is concluded that the traffic-linked ultrafine particle fraction PM0.056 in the atmosphere by the roadside of an urban area is clastogenic and able to induce morphological transformation of mammalian cells. PMID:24895420

Verma, Mukesh K; Poojan, Shiv; Sultana, Sarwat; Kumar, Sushil

2014-09-01

345

Surface and bulk characterization of an ultrafine South African coal fly ash with reference to polymer applications  

NASA Astrophysics Data System (ADS)

South African coal-fired power stations produce about 25 million tons of fly ash per annum, of which only approximately 5% is currently reused. A growing concern about pollution and increasing landfill costs stimulates research into new ways to utilize coal fly ash for economically beneficial applications. Fly ash particles may be used as inorganic filler in polymers, an application which generally requires the modification of their surface properties. In order to design experiments that will result in controlled changes in surface chemistry and morphology, a detailed knowledge of the bulk chemical and mineralogical compositions of untreated fly ash particles, as well as their morphology and surface properties, is needed. In this paper, a combination of complementary bulk and surface techniques was explored to assess the physicochemical properties of a classified, ultrafine coal fly ash sample, and the findings were discussed in the context of polymer application as fillers. The sample was categorized as a Class F fly ash (XRF). Sixty-two percent of the sample was an amorphous glass phase, with mullite and quartz being the main identified crystalline phases (XRD, FTIR). Quantitative carbon and sulfur analysis reported a total bulk carbon and sulfur content of 0.37% and 0.16% respectively. The spatial distribution of the phases was determined by 2D mapping of Raman spectra, while TGA showed a very low weight loss for temperatures ranging between 25 and 1000 °C. Individual fly ash particles were characterized by a monomodal size distribution (PSD) of spherical particles with smooth surfaces (SEM, TEM, AFM), and a mean particle size of 4.6 ?m (PSD). The BET active surface area of this sample was 1.52 m2/g and the chemical composition of the fly ash surface (AES, XPS) was significantly different from the bulk composition and varied considerably between spheres. Many properties of the sample (e.g. spherical morphology, small particle size, thermal stability) appeared to be suitable for its applicability as filler in polymers, although the wide variation in surface composition between individual particles may challenge the development of a suitable surface modification technique. The observation that the bulk and surface compositions of the particles were so intrinsically different, strongly suggested that surface characterization is important when considering compatibility between matrices when applying fly ash as filler in polymers.

van der Merwe, E. M.; Prinsloo, L. C.; Mathebula, C. L.; Swart, H. C.; Coetsee, E.; Doucet, F. J.

2014-10-01

346

Recent developments in the particle size distribution modeling of fluidized-bed olefin polymerization reactors  

Microsoft Academic Search

In the present study, a steady-state population balance model is developed for the prediction of the particle size distribution in ethylene copolymerization FBRs operating under moderate particle agglomeration conditions. To calculate the growth rate of a single particle under internal and external heat and mass transfer limitations, the polymeric flow model (PFM) is employed. The PFM is solved together with

H. Yiannoulakis; A. Yiagopoulos; C. Kiparissides

2001-01-01

347

Low-temperature, facile fabrication of ultrafine Cu2O networks by anodization on TiO2 nanotube arrays  

NASA Astrophysics Data System (ADS)

A green and facile process was developed to fabricate ultrafine p-type Cu2O single crystal nanowires by anodizing copper (Cu0) particles preloaded on TiO2 nanotube arrays. The Cu2O nanowires with a diameter of less than 5 nm were assembled on the top surface of n-type TiO2 nanotube arrays, constructing a novel p-n junction heterostructure with larger specific surface area compared to the unmodified TiO2 nanotube arrays. X-ray diffractometer (XRD) and high-resolution transmission electron microscopy (HRTEM) were employed to demonstrate that the resulting Cu2O was single crystalline. The composite Cu2O/TiO2 nanotube arrays exhibited significantly enhanced response to the visible light, resulting from Cu2O with a narrow-band gap. Furthermore, under visible light irradiation, enhanced efficiency in separating photogenerated hole-electron pairs was achieved due to the potential difference generated on the p-n interface. A possible mechanism was proposed to explain the formation of crystal Cu2O nanowires.

Luo, S. L.; Li, Y.; Yang, L. X.; Liu, C. B.; Su, F.; Chen, Y.

2012-10-01

348

Precise size control over ultrafine rutile titania nanocrystallites in hierarchical nanotubular silica/titania hybrids with efficient photocatalytic activity.  

PubMed

Hierarchical-structured nanotubular silica/titania hybrids incorporated with particle-size-controllable ultrafine rutile titania nanocrystallites were realized by deposition of ultrathin titania sandwiched silica gel films onto each nanofiber of natural cellulose substances (e.g., common commercial filter paper) and subsequent flame burning in air. The rapid flame burning transforms the initially amorphous titania into rutile phase titania, and the silica gel films suppress the crystallite growth of rutile titania, thereby achieving nano-precise size regulation of ultrafine rutile titania nanocrystallites densely embedded in the silica films of the nanotubes. The average diameters of these nanocrystallites are adjustable in a range of approximately 3.3-16.0 nm by a crystallite size increment rate of about 2.4 nm per titania deposition cycle. The silica films transfer the electrons activated by crystalline titania and generate catalytic reactive species at the outer surface. The size-tuned ultrafine rutile titania nanocrystallites distributed in the unique hierarchical networks significantly improve the photocatalytic performance of the rutile phase titania, thereby enabling a highly efficient photocatalytic degradation of the methylene blue dye under ultraviolet light irradiation, which is even superior to the pure anatase-titania-based materials. The facile stepwise size control of the rutile titania crystallites described here opens an effective pathway for the design and preparation of fine-nanostructured rutile phase titania materials to explore potential applications. PMID:23843325

Gu, Yuanqing; Huang, Jianguo

2013-08-12

349

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

350

Stability of ultrafine lamellar structures during aging in two-phase {gamma}-TiAl alloys  

SciTech Connect

Two-phase {gamma}-tail alloys such as PM Ti-47Al-2Cr-2Nb or Ti-47Al- 2Cr-1Nb-Ta hot extruded above the {alpha}-transus temperature have unique refined-colony/ultrafine lamellar structures. These lamellar microstructures consist of very fine laths of the {gamma} and {alpha}{sub 2} phases, with average interlamellar spacings of 100 nm and {alpha}{sub 2}-{alpha}{sub 2} spacings of 200 nm, and are dominated by {gamma}/{alpha}{sub 2} interfaces. This ultrafine lamellar structure remains stable during 900 C heat treatment for 2 h, but becomes unstable after 4 h at 982 C. This structure remains stable in both alloys after aging for >5000 h at 800 C but disappears completely at 1000 C. Continuous coarsening begins with dissolution of fine {alpha}{sub 2} lamellea. The aged Ta-modified alloy shows similar lamellar coarsening behavior within the colonies but has more discontinuous coarsening of the intercolony {gamma} with new precipitation of coarse {alpha}{sub 2} and {beta} phase particles. Analytical electron microscopy show that changes in {alpha}{sub 2} phase composition correlate with microstructural instability.

Maziasz, P.J.; Liu, C.T.; Wright, J.L.

1997-08-01

351

Formation of Splats from Suspension Particles with Solid Inclusions Finely Dispersed in a Melted Metal Matrix  

NASA Astrophysics Data System (ADS)

A theoretical model has been developed to describe the splats formation from composite particles of several tens of micrometers in size whose liquid metal binder contains a high volume concentration of ultra-fine refractory solid inclusions uniformly distributed in the binder. A theoretical solution was derived, enabling evaluation of splat thickness and diameter, and also the contact temperature at the particle-substrate interface, under complete control of key physical parameters (KPPs) of the spray process (impact velocity, temperature, and size of the particle, and substrate temperature) versus the concentration of solid inclusions suspended in the metal-binder melt. Using the solution obtained, the calculations performed demonstrate the possibility of formulating adequate requirements on the KPPs of particle-substrate interaction providing a deposition of ceramic-metal coatings with predictable splat thickness and degree of particle flattening on the substrate, and also with desired contact temperature during the formation of the first coating monolayer.

Solonenko, O. P.

2012-12-01

352

Fracture of Ni with grain-size from nanocrystalline to ultrafine scale under cyclic loading  

SciTech Connect

A two-step fatigue loading scheme was developed to study the fracture characteristics of nanocrystalline and ultrafine-grained Ni, with grain-sizes of 23 and 260nm, respectively. Cyclic work-hardening, measured by the mid-loop width during cycling, was observed in both types of material in the first loading step. The loop width increases rapidly as the load is upgraded in the second step. Crack initiation and striation have been observed for the first time in nanocrystalline Ni.

Cheng, Sheng [ORNL; Stoica, Alexandru Dan [ORNL; Wang, Xun-Li [ORNL; Wang, Gy [University of Tennessee, Knoxville (UTK); Choo, Hahn [ORNL; Liaw, Peter K [University of Tennessee, Knoxville (UTK)

2007-01-01

353

Development of the General AntiParticle Spectrometer (GAPS)  

NASA Astrophysics Data System (ADS)

The GAPS experiment is foreseen to carry out a dark matter search by searching for low energy cosmic ray antideuterons with a novel detection approach. The theoretically predicted antideuteron flux resulting from secondary interactions of primary cosmic rays, e.g. protons, with the interstellar medium is very low. So far not a single cosmic antideuteron has been detected by any experiment, but well-motivated theories beyond the standard model of particle physics contain viable dark matter candidates, which could lead to a significant enhancement of the antideuteron flux due to self-annihilation of dark matter particles. GAPS is designed to achieve its goals via a series of ultra-long duration balloon flights at high altitude in Antarctica. In June 2012, a successful prototype balloon flight from the balloon base in Taiki, Japan was carried out. The presentation will report on the data analysis of the prototype flight and discuss the implications for the design of the full GAPS payload.

Von Doetinchem, Philip

354

The relationship between aviation activities and ultrafine particulate matter concentrations near a mid-sized airport  

NASA Astrophysics Data System (ADS)

Aircraft contribute to emissions of ultrafine particulate matter (UFP) and other air pollutants, with corresponding impacts on community-level exposures near active airports. However, it is challenging to isolate the contribution of aircraft from local road traffic and other nearby combustion sources. In this study, we used high-resolution monitoring and flight activity data to quantify contributions from landing and take-off operations (LTO) to UFP concentrations. UFP concentrations were monitored with 1-min resolution at four monitoring sites surrounding T.F. Green Airport in Warwick, RI, in three one-week campaigns across different seasons in 2007 and 2008. Along with pollutant monitoring, wind data were collected and runway-specific LTO data were obtained from airport officials. We developed regression models in which wind speed and direction were included as a nonparametric smooth spatial term using thin-plate splines applied to wind velocity vectors and fitted using linear mixed models. To better pinpoint the timing in the LTO cycle most contributing to elevated concentrations, we used regression models with lag terms for flight activity (ranging from 5 min before to 5 min after the departure or arrival). Results suggest positive associations between UFP concentrations and LTO activities, especially for departures when an aircraft moves near or passes a monitoring site. Departures of jet engine aircrafts on a runway proximate to one of the monitors have a maximal impact 1 min prior to take-off, with median absolute contributions during those minutes of 7400 particles cm-3 (range: 1100-70,000 particles cm-3). Across all observations, our models indicate median (95th, 99th percentile) percent contribution for all LTO activities of 9.8% (54%, 72%) and 6.6% (39%, 55%) for the two sites proximate to the airport's principal runway, and 4.7% (24%, 36%) and 1.8% (22%, 31%) for the remaining two sites. Our analysis illustrates the complexity of aviation impacts on local air quality and allows for quantification of the marginal contribution of LTO activity relative to other nearby sources.

Hsu, Hsiao-Hsien; Adamkiewicz, Gary; Andres Houseman, E.; Vallarino, Jose; Melly, Steven J.; Wayson, Roger L.; Spengler, John D.; Levy, Jonathan I.

2012-04-01

355

Simulation of particles transport and coagulation during the RESS process  

NASA Astrophysics Data System (ADS)

The rapid expansion of supercritical solution (RESS) is a promising process for the production of small particles with a narrow size distribution. It involves an expansion of a supercritical solution through a small nozzle to generate a rapid nucleation and then the formation of ultrafine particles. The particles are transported by a powerful jet developed in the expansion chamber. The particle size distribution (PSD) of the obtained fine powders depends on the hydrodynamic conditions in the pre- and post-expansion unit, the nature of solute-solvent system, as well as on the nozzle geometry, and diameter. In this work, we have developed a numerical simulation of both transport and Brownian coagulation of spherical particles in the expansion chamber by resolving the general dynamic equation (GDE). This simulation has permitted to control the temporal evolution of PSD characterizing each class of particles. These PSD field evolutions show that the particles of each class get round the Mach disk taking refuge on the jet boundaries where the Brownian coagulation is more pronounced. Therefore, these particles whose size depends on thermodynamic and geometrical conditions are deposited on the flat plate as a ring. We notice that the narrowest distribution function of the deposited particles on the flat plate is obtained for the largest nozzle orifice diameters and the lowest expansion pressure.

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

2008-08-01

356

Development of analytical and numerical models predicting the deposition rate of electrically charged particles in turbulent channel flows  

E-print Network

An analytical model is established to predict an electrostatically charged particle deposition as a function of particle size in fully-developed turbulent pipe flow. The convectivediffusion flux equation is solved for the particle concentration as a...

Ko, Hanseo

2012-06-07

357

Doped hydrophobic silica nano- and micro-particles as novel agents for developing latent fingerprints.  

PubMed

Novel hydrophobic silica based particles have been developed to visualise latent fingerprints. The composition of the particles has been designed to maximise both hydrophobic and ionic interactions between a variety of coloured and fluorescent reporter molecules and the silicate backbone within the particles. The resulting doped particles retain the incorporated dyes with high affinity. In addition, a variety of sub-particles have also been embedded to again produce coloured or magnetisable hydrophobic particles. The particles can be harvested as nanoparticles or microparticles. The former are applied to latent fingerprints as an aqueous suspension and the latter as a dusting agent using brushes or a magnetic wand. Examples of the prints produced using these agents are given. The resulting prints have good definition. PMID:17418514

Theaker, Brenden J; Hudson, Katherine E; Rowell, Frederick J

2008-01-15

358

Benign joining of ultrafine grained aerospace aluminum alloys using nanotechnology.  

PubMed

Ultrafine grained aluminum alloys have restricted applicability due to their limited thermal stability. Metalized 7475 alloys can be soldered and brazed at room temperature using nanotechnology. Reactive foils are used to release heat for milliseconds directly at the interface between two components leading to a metallurgical joint without significantly heating the bulk alloy, thus preserving its mechanical properties. PMID:22105915

Longtin, Rémi; Hack, Erwin; Neuenschwander, Jürg; Janczak-Rusch, Jolanta

2011-12-22

359

Continuous processing of ultrafine grained Al by ECAP–Conform  

Microsoft Academic Search

In this paper, we report a new severe plastic deformation (SPD) technique, which combines equal channel angular pressing (ECAP) with Conform, to process ultrafine grained (UFG) materials in a continuous manner. ECAP in its original form can only process short metal bars and is labor intensive. Conform is a technique that has been used to continuously form metals into various

Georgy J. Raab; Ruslan Z. Valiev; Terry C. Lowe; Yuntian T. Zhu

2004-01-01

360

Ballistic performance of nanocrystalline and nanotwinned ultrafine crystal steel  

E-print Network

Ballistic performance of nanocrystalline and nanotwinned ultrafine crystal steel Jaime Fronta to be relevant candidates for ballistic protection. The aim of the present work is to compare their ballistic show a lower energy absorption than coarse-grained steel under ballistic loading, but under equal

Suresh, Subra

361

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

362

Preparation of ultrafine MnO 2 powders by the solid state method reaction of KMnO 4 with Mn(II) salts at room temperature  

Microsoft Academic Search

A novel route was used to prepare ultrafine powders of MnO2, i.e. the solid state reaction of KMnO4 with manganese acetate or manganese chloride at or near room temperature. The results of XPS and chemical analysis revealed that the main valence state of synthesized manganese oxides was 4. TEM and XRD showed that the average particle sizes were in the

Qingwen Li; Guoan Luo; Juan Li; Xi Xia

2003-01-01

363

Effects of TiC\\/TiN addition on the microstructure and mechanical properties of ultra-fine grade Ti (C, N)–Ni cermets  

Microsoft Academic Search

Two series of Ti (C, N)-based cermets, one with TiC addition and the other with TiN addition, were fabricated by conventional powder metallurgy technique. The initial powder particle size of the main hard phase components (Ti (C, N), TiC and TiN) was nano\\/submicron-sized, in order to achieve an ultra-fine grade final microstructure. The TiC and TiN addition can improve the

Ning Liu; Sheng Chao; Xinming Huang

2006-01-01

364

Ferrite and Spheroidized Cementite Ultrafine Microstructure Formation in an Fe-0.67 Pct C Steel for Railway Wheels under Simulated Service Conditions  

NASA Astrophysics Data System (ADS)

The microstructure development of a high-carbon steel (0.67 pct C) for railway wheels as they are affected by rolling contact with rail tracks and by cyclic frictional heat from braking is studied in the vicinity of the contact surface by scanning electron microscopy (SEM) and electron backscattered diffraction. An ultrafine microstructure consisting of ferrite grains with a size of less than 1 ?m and spheroidized cementite particles is formed in the region up to 100 ?m below the contact surface. The generation of low-angle sub-boundaries associated with the rearrangement of accumulated dislocations involved in continuous recrystallization of ferrite microstructure contributes to the microstructure refinement at temperatures lower than A1 temperature (1000 K). Fine spheroidized cementite particles with uniform distribution obstruct the migration of high-angle grain boundaries, by which the dislocation density is maintained sufficiently high for the formation of sub-boundaries. The formation of a texture, corresponding to the surface texture typically formed in low-carbon steels by hot rolling without lubrication at ferritic temperatures, is observed in the ultrarefined microstructure region. The results drawn from this study strongly indicate the occurrence of “ in-situ microstructure control” under service conditions.

Handa, Kazuyuki; Kimura, Yoshisato; Mishima, Yoshinao

2009-12-01

365

Development of phonon-mediated cryogenic particle detectors with electron and nuclear recoil discrimination  

Microsoft Academic Search

Observations have shown that galaxies, including our own, are surrounded by halos of ``dark matter''. One possibility is that this may be an undiscovered form of matter, weakly interacting massive particles (WIMPs). This thesis describes the development of silicon based cryogenic particle detectors designed to directly detect interactions with these WIMPs. These detectors are part of a new class of

Sae Woo Nam

1999-01-01

366

Modeling particle deposition from fully developed turbulent flow in ventilation duct  

Microsoft Academic Search

This paper proposes an improved Eulerian model to predict particle deposition velocity in fully developed turbulent duct flow. The model is modified based on the three-layer model by Lai and Nazaroff (Journal of Aerosol Science, 31, 463–476, 2000), accounting for turbophoresis as well as Brownian diffusion, turbulent diffusion and gravitational settling. An expression relating the turbophoretic velocity to particle relaxation

Bin Zhao; Jun Wu

2006-01-01

367

Development and analysis of startup strategies for particle bed nuclear rocket engine  

Microsoft Academic Search

The particle bed reactor (PBR) nuclear thermal propulsion rocket engine concept is the focus of the Air Force's Space Nuclear Thermal Propulsion program. While much progress has been made in developing the concept, several technical issues remain. Perhaps foremost among these concerns is the issue of flow stability through the porous, heated bed of fuel particles. There are two complementary

David E. Suzuki

1993-01-01

368

Nanocasting Synthesis of Ultrafine WO3 Nanoparticles for Gas Sensing Applications  

PubMed Central

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

2010-01-01

369

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

370

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

371

Enormous Enhancement of van der Waals Forces between Small Silver Particles  

Microsoft Academic Search

Dispersion forces enhance the coagulation rate of small particles in a gas. Measurements of coagulation rates on ultrafine Ag and C particles with radii of 3-16 nm were performed. The results obtained with C particles almost agree with the expectations based on bulk electronic properties. However, Ag particles 14 nm in radius exhibit a very large coagulation rate. It points

Heinz Burtscher; Andreas Schmidt-Ott

1982-01-01

372

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

373

DEVELOPMENT AND LABORATORY CHARACTERIZATION OF A PROTOTYPE COARSE PARTICLE CONCENTRATOR FOR INHALATION TOXICOLOGICAL STUDIES. (R825270)  

EPA Science Inventory

This paper presents the development and laboratory characterization of a prototype slit nozzle virtual impactor that can be used to concentrate coarse particles. A variety of physical design and flow parameters were evaluated including different acceleration and collection sli...

374

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

375

Development and Evaluation of a PM 10 Impactor-Inlet for a Continuous Coarse Particle Monitor  

Microsoft Academic Search

Conventional PM 10 inlets available operate at a flow rate of 16.7 l\\/min. The purpose of this study was to develop and test a PM 10 inlet designed to operate at 50 l\\/min to be used with a recently developed continuous coarse particle monitor (Misra et al.). Laboratory tests using polystyrene latex particles established the inlet's 50% cutpoint at 9.5

Chandan Misra; Michael D. Geller; Constantinos Sioutas; Paul A. Solomon

2003-01-01

376

PROJECT 4 -- TRANSPORT AND FATE PARTICLES  

EPA Science Inventory

These experiments use size and surface-fixed charge defined ultrafine particulates to provide baseline information on the time course and extent of their systemic absorption. Understanding the nature of particle transport in blood will be important for recognizing the likeliho...

377

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

378

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

379

Shape effect of ultrafine-grained structure on static fracture toughness in low-alloy steel  

NASA Astrophysics Data System (ADS)

A 0.4C-2Si-1Cr-1Mo steel with an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 773 K and subsequent annealing at 973 K. A static three-point bending test was conducted at ambient temperature and at 77 K. The strength-toughness balance of the developed steels was markedly better than that of conventionally quenched and tempered steel with a martensitic structure. In particular, the static fracture toughness of the UFEG steel, having a yield strength of 1.86 GPa at ambient temperature, was improved by more than 40 times compared with conventional steel having a yield strength of 1.51 GPa. Furthermore, even at 77 K, the fracture toughness of the UFEG steel was about eight times higher than that of the conventional and UFG steels, despite the high strength of the UFEG steel (2.26 GPa). The UFG steel exhibited brittle fracture behavior at 77 K, as did the conventional steel, and no dimple structure was observed on the fracture surface. Therefore, it is difficult to improve the low-temperature toughness of the UFG steel by grain refinement only. The shape of crystal grains plays an important role in delamination toughening, as do their refinement and orientation.

Inoue, Tadanobu; Kimura, Yuuji; Ochiai, Shojiro

2012-06-01

380

Evidences for New Particle Formation in the Arctic as a Part of TOPSE Atmospheric Nucleation Event  

NASA Astrophysics Data System (ADS)

Simultaneous measurements of ultrafine particles and precursor gases show evidences of new particle formation over a wide range of latitude in the free tropospheric Arctic region. However, the exact mechanism of new particle formation is uncertain. In this study, in-situ measurements taken during deployment 3 (Flight 16, March 7, 2000, Churchill-Churchill, 13:25-18:33 GMT) as a part of Tropospheric Ozone Production about Spring Equinox (TOPSE) experiment, over Western Canada were used for comparison with the model predictions. Using a combination of satellite derived brightness temperature, air parcel backward trajectory information, in-situ measurements of aerosol and precursor gases and aerosol microphysical model [Tripathi et al., 2004] driven by parameterized ion induced nucleation [Modgil et al., 2005], we have investigated the plausible mechanism responsible for, and factors leading to, new particle formation in the middle to upper troposphere during TOPSE atmospheric nucleation event. The reasonable agreement between model predicted and observed ultrafine particles of diameter 3 to 4 nm and 3 to 8 nm suggest that new particle formation is likely to occur by ion induced nucleation mechanism during TOPSE nucleation event. A significant finding is that the lowering of pre-existing particle surface, in the region of cloud outflow, triggered particle nucleation in this region. These studies indicate that, at typical middle to upper tropospheric conditions of Arctic, ion mechanism is an important source of ultrafine particles and these freshly particles can grow to act as cloud condensation nuclei (CCN), which have implications for cloud radiative properties. References Modgil, M. S., Sanjeev Kumar, S. N. Tripathi, and E. R. Lovejoy, A parameterization of ion-induced nucleation of sulfuric acid and water for atmospheric conditions, J. Geophys. Res., In press, 2005. Tripathi, S. N., X. P. Vancassel, R. G. Grainger, and H. L. Rogers, A Fast Stratospheric Aerosol Microphysical Model (SAMM): H2SO4-H2O Aerosol Development and Validation, AOPP Memorandum 2004.1, Department of Physics, University of Oxford, 2004. http://www.atm.ox.ac.uk/main/research/technical.html

Tripathi, S. N.; Kanawade, V. P.

2005-12-01