WorldWideScience

Sample records for airborne particle size

  1. Particle sizing of airborne radioactivity field measurements at Olympic Dam

    International Nuclear Information System (INIS)

    On July 1, 1991 the Australian Radiation Laboratory (ARL) commenced a two year project entitled - Particle sizing of airborne radioactivity, funded by a Mining and Quarrying Occupational Health and Safety Committee - grant (submission No. 9138). This study was set out to measure airborne radioactivity size distributions in an underground uranium mine, in order to provide better estimates of the health risks associated with inhalation of airborne radiation in the work place. These measurements included both active and passive measurement of radon gas, continuous and spot sample of radon daughter levels, as well as wire screen diffusion battery measurements of the radon daughter size distributions. The results of measurements at over 50 sites within the mine are reported, together with the calculated dose conversion factors derived from the older dosimetric models and from the new ICRP lung model using the computer code RADEP. The results showed that the ventilation is relatively uniform within the mine and the radon daughter concentrations are kept to less than 20% of the equilibrium concentration. The radon and radon daughter concentrations showed marked variability with both time and position within the mine. It is concluded that the present radiation protection methods and dose conversion factors used in Australia provide a good estimate of the radiation risk for the inhalation of radon progeny. 29 refs., 8 tabs., 9 figs

  2. Particle size analysis in estimating the significance of airborne contamination

    International Nuclear Information System (INIS)

    In this report information on pertinent methods and techniques for analysing particle size distributions is compiled. The principles underlying the measurement methods are described, and the merits of different methods in relation to the information being sought and to their usefulness in the laboratory and in the field are explained. Descriptions on sampling methods, gravitational and inertial particle separation methods, electrostatic sizing devices, diffusion batteries, optical sizing techniques and autoradiography are included. Finally, the report considers sampling for respirable activity and problems related to instrument calibration

  3. Size distribution of airborne mist and endotoxin-containing particles in metalworking fluid environments.

    Science.gov (United States)

    Wang, Hongxia; Reponen, Tiina; Lee, Shu-An; White, Eugene; Grinshpun, Sergey A

    2007-03-01

    The objective of the study was to investigate size-selective concentrations of airborne particles and endotoxin in metalworking fluid (MWF) environments. The experiments were conducted under two conditions: (1) MWF collected in the field was aerosolized with a laboratory-scale simulator (MWF simulator) in the laboratory; and (2) MWFs were aerosolized during routine field operations. All experiments included size-selective measurement of airborne concentrations of particle numbers and endotoxin mass using an electrical low-pressure impactor. During field sampling, the total microbial and endotoxin concentrations in the air were also measured with a BioSampler, and the mass concentration of MWF mists was measured with a photometer. Airborne particle concentrations were highest in the fine particle size ranges in the areas affected by MWFs. Relatively high concentrations of endotoxin were detected at particle size below 0.39 mum, which is smaller than the size of intact bacterial cells. The total microbial and endotoxin analysis revealed high microbial contamination in one sampling site although the total particle mass was not elevated. It was concluded that MWF sites can be contaminated with high concentrations of fine particles, and these fine particles may contain microbial components, such as endotoxin. The results call for the size-selective measurement of particles and endotoxin for more comprehensive exposure assessment in MWF facilities. PMID:17237021

  4. Airborne endotoxin associated with particles of different sizes and affected by water content in handled straw.

    Science.gov (United States)

    Madsen, A M; Nielsen, S H

    2010-07-01

    High exposures to endotoxin are observed in environments where organic materials are handled and lower exposures are found in e.g. indoor air. Inhaled endotoxin contributes significantly to the induction of airway inflammation and dysfunction. The size of an inhaled particle influences the deposition in the airways and the following health symptoms. The objective is to characterise the distribution of endotoxin on airborne particles of different sizes in straw storage halls with high exposure and in other environments with lower exposure levels to endotoxin. Furthermore we have studied the influence of water content of handled straw on the size distribution of endotoxin containing particles. Total, inhalable, thoracic and respirable endotoxin and particles have each been quantified in aerosols from boiler rooms and straw storage halls at 24 power plants, including 21 biofuel plants. Inhalable, thoracic and respirable endotoxin have been quantified in aerosols from offices and outdoor air. The endotoxin concentration was higher in airborne thoracic dust than in airborne 'total dust'. The median respirable fraction in the straw storage halls, boiler rooms at biofuel plants, boiler rooms at conventional plants, offices and outdoors was respectively 42%, 9%, 19%, 24% and 34%. Thoracic endotoxin per number of thoracic particles was higher than respirable endotoxin per number of respirable particles at the biofuel plants. In straw storage halls the fraction of endotoxin of respirable size was highest on the days with lowest water content in the received straw. Furthermore the exposures to all endotoxin fractions were highest on days with the lowest water content in the received straw. In conclusion the highest exposures and concentrations of endotoxin occur or tend to occur from thoracic dust. A high variation in endotoxin concentrations and in fractions of respirable or thoracic size is found in the different working areas. This is important in the risk assessment and

  5. Cloud particle size distributions measured with an airborne digital in-line holographic instrument

    Directory of Open Access Journals (Sweden)

    J. P. Fugal

    2009-03-01

    Full Text Available Holographic data from the prototype airborne digital holographic instrument HOLODEC (Holographic Detector for Clouds, taken during test flights are digitally reconstructed to obtain the size (equivalent diameters in the range 23 to 1000 μm, three-dimensional position, and two-dimensional profile of ice particles and then ice particle size distributions and number densities are calculated using an automated algorithm with minimal user intervention. The holographic method offers the advantages of a well-defined sample volume size that is not dependent on particle size or airspeed, and offers a unique method of detecting shattered particles. The holographic method also allows the volume sample rate to be increased beyond that of the prototype HOLODEC instrument, limited solely by camera technology.

    HOLODEC size distributions taken in mixed-phase regions of cloud compare well to size distributions from a PMS FSSP probe also onboard the aircraft during the test flights. A conservative algorithm for detecting shattered particles utilizing the particles depth-position along the optical axis eliminates the obvious ice particle shattering events from the data set. In this particular case, the size distributions of non-shattered particles are reduced by approximately a factor of two for particles 15 to 70 μm in equivalent diameter, compared to size distributions of all particles.

  6. Direct Characterization of Airborne Particles Associated with Arsenic-rich Mine Tailings: Particle Size Mineralogy and Texture

    Energy Technology Data Exchange (ETDEWEB)

    M Corriveau; H Jamieson; M Parsons; J Campbell; A Lanzirotti

    2011-12-31

    Windblown and vehicle-raised dust from unvegetated mine tailings can be a human health risk. Airborne particles from As-rich abandoned Au mine tailings from Nova Scotia, Canada have been characterized in terms of particle size, As concentration, As oxidation state, mineral species and texture. Samples were collected in seven aerodynamically fractionated size ranges (0.5-16 {micro}m) using a cascade impactor deployed at three tailings fields. All three sites are used for recreational activities and off-road vehicles were racing on the tailings at two mines during sample collection. Total concentrations of As in the <8 {micro}m fraction varied from 65 to 1040 ng/m{sup 3} of air as measured by proton-induced X-ray emission (PIXE) analysis. The same samples were analysed by synchrotron-based microfocused X-ray absorption near-edge spectroscopy ({micro}XANES) and X-ray diffraction ({micro}XRD) and found to contain multiple As-bearing mineral species, including Fe-As weathering products. The As species present in the dust were similar to those observed in the near-surface tailings. The action of vehicles on the tailings surface may disaggregate material cemented with Fe arsenate and contribute additional fine-grained As-rich particles to airborne dust. Results from this study can be used to help assess the potential human health risks associated with exposure to airborne particles from mine tailings.

  7. Size and composition of airborne particles from pavement wear, tires, and traction sanding.

    Science.gov (United States)

    Kupiainen, Kaarle J; Tervahattu, Heikki; Räisänen, Mika; Mäkelä, Timo; Aurela, Minna; Hillamo, Risto

    2005-02-01

    Mineral matter is an important component of airborne particles in urban areas. In northern cities of the world, mineral matter dominates PM10 during spring because of enhanced road abrasion caused by the use of antiskid methods, including studded tires and traction sanding. In this study, factors that affect formation of abrasion components of springtime road dust were assessed. Effects of traction sanding and tires on concentrations, mass size distribution, and composition of the particles were studied in a test facility. Lowest particle concentrations were observed in tests without traction sanding. The concentrations increased when traction sand was introduced and continued to increase as a function of the amount of aggregate dispersed. Emissions were additionally affected by type of tire, properties of traction sand aggregate, and driving speed. Aggregates with high fragmentation resistance and coarse grain size distribution had the lowest emissions. Over 90% of PM10 was mineral particles. Mineralogy of the dust and source apportionment showed that they originated from both traction sand and pavement aggregates. The remaining portion was mostly carbonaceous and originated from tires and road bitumen. Mass size distributions were dominated by coarse particles. Contribution of fine and submicron size ranges were approximately 15 and 10% in PM10, respectively. PMID:15757329

  8. Direct characterization of airborne particles associated with arsenic-rich mine tailings: Particle size, mineralogy and texture

    Energy Technology Data Exchange (ETDEWEB)

    Corriveau, M.C. [Department of Geological Sciences and Geological Engineering, Queen' s University, Kingston, Ontario, K7L 3N6 (Canada); Jamieson, H.E., E-mail: jamieson@geol.queensu.ca [Department of Geological Sciences and Geological Engineering, Queen' s University, Kingston, Ontario, K7L 3N6 (Canada); Parsons, M.B. [Geological Survey of Canada (Atlantic), Natural Resources Canada, Dartmouth, Nova Scotia, B2Y 4A2 (Canada); Campbell, J.L. [Guelph-Waterloo Physics Institute, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Lanzirotti, A. [Center for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637 (United States)

    2011-09-15

    Highlights: > Airborne dust from As-rich gold mine tailings used for recreation was collected. > Total concentrations of arsenic in the <8 {mu}m fraction varied from 65 to 1040 ng/m{sup 3}. > Multiple As minerals in dust are comparable with near-surface tailings samples. - Abstract: Windblown and vehicle-raised dust from unvegetated mine tailings can be a human health risk. Airborne particles from As-rich abandoned Au mine tailings from Nova Scotia, Canada have been characterized in terms of particle size, As concentration, As oxidation state, mineral species and texture. Samples were collected in seven aerodynamically fractionated size ranges (0.5-16 {mu}m) using a cascade impactor deployed at three tailings fields. All three sites are used for recreational activities and off-road vehicles were racing on the tailings at two mines during sample collection. Total concentrations of As in the <8 {mu}m fraction varied from 65 to 1040 ng/m{sup 3} of air as measured by proton-induced X-ray emission (PIXE) analysis. The same samples were analysed by synchrotron-based microfocused X-ray absorption near-edge spectroscopy ({mu}XANES) and X-ray diffraction ({mu}XRD) and found to contain multiple As-bearing mineral species, including Fe-As weathering products. The As species present in the dust were similar to those observed in the near-surface tailings. The action of vehicles on the tailings surface may disaggregate material cemented with Fe arsenate and contribute additional fine-grained As-rich particles to airborne dust. Results from this study can be used to help assess the potential human health risks associated with exposure to airborne particles from mine tailings.

  9. Measuring the trace elemental composition of size-resolved airborne particles.

    Science.gov (United States)

    Herner, Jorn D; Green, Peter G; Kleeman, Michael J

    2006-03-15

    A new method to measure the trace elemental composition of size-resolved airborne particles that uses acetone extraction followed by ICPMS analysis is compared to three other established methods: copper anode XRF, molybdenum anode XRF, and an ICPMS method that uses HF digestion. The method detection limit (MDL), accuracy, and precision of each method is studied through the analysis of ambient samples collected in California. The MDLs of the new acetone-ICPMS method are similar to MDLs for the established HF-ICPMS method. Both sets of ICPMS MDLs are 1-3 orders of magnitude lower than XRF MDLs for approximately 50 elements other than the light crustal elements such as silicon, sulfur, calcium, and zinc. The accuracy of the acetone-ICPMS method was verified by comparison to measurements made using ion chromatography and the HF-ICPMS method. The acetone-ICPMS analysis method was more precise than the conventional HF-ICPMS method for collocated measurements. Both ICPMS methods were more precise than XRF for most elements. The size distribution of 21 elements contained in ambient particles collected with cascade impactors could be measured with good precision using the new acetone-ICPMS analysis method: lithium, sulfur, potassium, titanium, vanadium, manganese, iron, gallium, germanium, arsenic, selenium, bromine, rubidium, strontium, cadmium, tin, antimony, barium, thallium, lead, and bismuth. It is likely that the size distribution of an additional 9 elements could also be measured when concentrations are sufficiently high: phosphorus, molybdenum, niobium, palladium, cesium, europium, holmium, platinum, and uranium. None of the conventional methods were able to measure the size distribution of these elements with acceptable precision under the conditions studied. The new acetone-ICPMS method should provide useful data for the study of the health effects of airborne particles. PMID:16570617

  10. Particle-size distribution of fission products in airborne dust collected at Tsukuba from April to June 1986

    International Nuclear Information System (INIS)

    The radioactivity released by the reactor accident at Chernobyl was detected in surface air at Tsukuba, Japan. Gamma-spectrometry of airborne dust collected using aerodynamic separation showed higher concentrations of radionuclides in fine particles. The particle-size distribution of radionuclides changed with time. (author)

  11. Airborne lidar measurements of smoke plume distribution, vertical transmission, and particle size

    International Nuclear Information System (INIS)

    Observations were made of a dense smoke plume downwind from a forest using the ALPHA-1 two-wavelength downward-looking airborne lidar system. Facsimile displays derived from lidar signatures depict plume dimensions, boundary layer height, and underlying terrain elevation. Surface returns are interpreted in terms of vertical transmissions as function of cross-plume distance. Results show significantly greater plume attenuation at 0.53-μm wavelength than at 1.06-μm, indicating approx.0.1-μm mean particle diameters of the presence of gaseous constituents that absorb the visible radiation. These results demonstrate the potential of multiple-wavelength airborne lidar for quantitative analysis of atmospheric particulate and gaseous constituents

  12. Instrument for Long-Path Spectral Extinction Measurements in Air: Application to Sizing of Airborne Particles

    Science.gov (United States)

    Paganini, Enrico; Trespidi, Franco; Ferri, Fabio

    2001-08-01

    A novel instrument that is capable of taking spectral extinction measurements over long optical paths (approximately 1 -100 m) in the UV, visible, and IR ranges is described. The instrument is fully automated, and the extinction spectrum is acquired in almost real time (approximately 5 -10 s) with a resolution of ~3 nm. Its sensitivity and accuracy were estimated by tests carried out in a clean room that showed that, for optical paths between 50 and 100 m, the extinction coefficient can be detected at levels of ~10-5 m-1 . Tests carried out on calibrated latex particles showed that, when it was combined with an appropriate inversion method, the technique could be profitably applied to characterize airborne particulate distributions. By carrying out measurements over optical paths of ~100 m, the instrument is also capable of detecting extinction coefficients that are due to aerosol concentrations well below the limits imposed by the European Economic Community for atmospheric pollution (150 g /m3 ). Scaled over optical paths of ~10 m, the limit imposed for particle emissions from industrial plants (10 mg /m3 ) can also be detected sensitively.

  13. Airborne particle sizes and sources found in indoor air. Rept. for Sep 89-Feb 90

    International Nuclear Information System (INIS)

    The paper summarizes results of a literature search into the sources, sizes, and concentrations of particles in indoor air, including the various types: plant, animal, mineral, combustion, home/personal care, and radioactive aerosols. The information, presented in a summary figure, has been gathered for use in designing test methodologies for air cleaners and other mitigation approaches and to aid in the selection of air cleaners. (NOTE: As concern about indoor air quality has grown, understanding indoor aerosols has become increasingly important so that control techniques may be implemented to reduce damaging health effects and soiling problems. Particle diameters must be known to predict dose or soiling and to determine efficient mitigation techniques.)

  14. Concentration and particle size of airborne toxic algae (brevetoxin) derived from ocean red tide events.

    Science.gov (United States)

    Cheng, Yung Sung; McDonald, Jacob D; Kracko, Dean; Irvin, C Mitch; Zhou, Yue; Pierce, Richard H; Henry, Michael S; Bourdelaisa, Andrea; Naar, Jerome; Baden, Daniel G

    2005-05-15

    Red tides in the Gulf of Mexico are formed by blooms of the dinoflagellate Karenia brevis, which produces brevetoxins (PbTx). Brevetoxins can be transferred from water to air in the wind-powered whitecapped waves during red tide episodes. Inhalation exposure to marine aerosol containing PbTx causes respiratory problems. A liquid chromatograph/ tandem mass spectrometric method was developed for the detection and quantitation of several PbTxs in ambient samples collected during red tide events. This method was complemented by a previously developed antibody assay that analyzes the entire class of PbTx compounds. The method showed good linearity, accuracy, and reproducibility, allowing quantitation of PbTx compounds in the 10 pg/m3 range. Air concentrations of PbTxs and brevenal for individual samples ranged from 0.01 to 80 ng/m3. The particle size showed a single mode with a mass median diameter between 6 and 10 microm, which was consistent for all of the PbTx species that were measured. Our results imply that individual PbTxs were from the same marine aerosol or from marine aerosol that was produced from the same process. The particle size indicated the likelihood of high deposition efficiency in the respiratory tract with the majority of aerosol deposited in the upper airways and small but not insignificant deposition in the lower airways. PMID:15954221

  15. On Airborne Nano/Micro-Sized Particles Released from Low-Metallic Automotive Brakes

    Czech Academy of Sciences Publication Activity Database

    Kukutschová, J.; Moravec, Pavel; Tomášek, V.; Matějka, V.; Smolík, Jiří; Schwarz, Jaroslav; Seidlerová, J.; Šafářová, K.; Filip, P.

    2011-01-01

    Roč. 159, č. 4 (2011), s. 998-1006. ISSN 0269-7491 Institutional research plan: CEZ:AV0Z40720504 Keywords : brake wear debris * nano particles * oxidative wear Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.746, year: 2011

  16. The impact of fireworks on airborne particles

    OpenAIRE

    R. Vecchi; Bernardoni, V.; Cricchio, D; A. D'Alessandro; P. Fermo; F. Lucarelli(Agenzia Spaziale Italiana); S. Nava; Piazzalunga, A.; Valli, G.

    2008-01-01

    Fireworks are one of the most unusual sources of pollution in atmosphere; although transient, these pollution episodes are responsible for high concentrations of particles (especially metals and organic compounds) and gases. In this paper, results of a study on chemical-physical properties of airborne particles (elements, ions, organic and elemental carbon and particles size distributions) collected during a fireworks episode in Milan (Italy) are reported. Elements typically emitted during py...

  17. Study on Size Distributions of Airborne Particles by Aircraft Observation in Spring over Eastern Coastal Areas of China

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; LIU Hongjie; YUE Xin; LI Hong; CHEN Jianhua; TANG Dagang

    2005-01-01

    The authors studied the size distributions of particles at an altitude of 2000 m by aircraft observation over eastern costal areas of China from Zhuhai, Guangdong to Dalian, Liaoning (0.47-30 μm, 57 channels,including number concentration distribution, surface area concentration distribution and mass concentration distribution). In these cities, the average daily concentrations of PM10 are very high. They are among the most heavily polluted cities in China. The main pollution sources are anthropogenic activities such as wood, coal and oil burning. The observed size distributions show a broad spectrum and unique multi-peak characteristics, indicating no significant impacts of individual sources from urban areas. These results are far different from the distribution type at ground level. It may reflect the comprehensive effect of the regional pollution characteristics. Monitoring results over big cities could to some extent reflect their pollution characteristics.

  18. Study of airborne particles generated by the impact of droplets

    International Nuclear Information System (INIS)

    A liquid droplet impinging onto surfaces occurs in many industrial and natural processes. The study of this phenomenon is fundamental in order to determine the potential sources of contamination in the case of scenarios of liquid falls such as dripping. There are very few data in the literature in the case of the impact of millimeter-size droplets. The purpose of our work is to study experimentally the particle emission during the impact of droplets onto a liquid film. Experiments were conducted to study the influence of the velocity and the diameter of the droplets, the height of the liquid film, the surface tension and viscosity of the liquid on the airborne particles. Our results, original, have made it possible to examine the relevance of existing relations, describing the transition between deposition and splash regimes, in order to determine the presence or not of airborne particles. The micro droplets produced, with diameters less than fifty micrometers, are characterised in terms of total mass and size distribution. Our results also show the influence of a combination of several factors on the production of airborne particles. For this reason, it is interesting to use dimensionless numbers, to describe the relationship between the inertial, viscosity and surface tension forces, in order to understand physically the emission of airborne particles. (author)

  19. Airborne soil organic particles generated by precipitation

    Science.gov (United States)

    Wang, Bingbing; Harder, Tristan H.; Kelly, Stephen T.; Piens, Dominique S.; China, Swarup; Kovarik, Libor; Keiluweit, Marco; Arey, Bruce W.; Gilles, Mary K.; Laskin, Alexander

    2016-06-01

    Airborne organic particles play a critical role in Earth's climate, public health, air quality, and hydrological and carbon cycles. However, sources and formation mechanisms for semi-solid and solid organic particles are poorly understood and typically neglected in atmospheric models. Laboratory evidence suggests that fine particles can be formed from impaction of mineral surfaces by droplets. Here, we use chemical imaging of particles collected following rain events in the Southern Great Plains, Oklahoma, USA and after experimental irrigation to show that raindrop impaction of soils generates solid organic particles. We find that after rain events, sub-micrometre solid particles, with a chemical composition consistent with soil organic matter, contributed up to 60% of atmospheric particles. Our irrigation experiments indicate that intensive water impaction is sufficient to cause ejection of airborne soil organic particles from the soil surface. Chemical imaging and micro-spectroscopy analysis of particle physico-chemical properties suggest that these particles may have important impacts on cloud formation and efficiently absorb solar radiation. We suggest that raindrop-induced formation of solid organic particles from soils may be a widespread phenomenon in ecosystems such as agricultural systems and grasslands where soils are exposed to strong, episodic precipitation events.

  20. Particle Size Analysis.

    Science.gov (United States)

    Barth, Howard G.; Sun, Shao-Tang

    1989-01-01

    Presents a review of research focusing on scattering, elution techniques, electrozone sensing, filtration, centrifugation, comparison of techniques, data analysis, and particle size standards. The review covers the period 1986-1988. (MVL)

  1. Measurement of airborne particle concentrations near the Sunset Crater volcano, Arizona.

    Science.gov (United States)

    Benke, Roland R; Hooper, Donald M; Durham, James S; Bannon, Donald R; Compton, Keith L; Necsoiu, Marius; McGinnis, Ronald N

    2009-02-01

    Direct measurements of airborne particle mass concentrations or mass loads are often used to estimate health effects from the inhalation of resuspended contaminated soil. Airborne particle mass concentrations were measured using a personal sampler under a variety of surface-disturbing activities within different depositional environments at both volcanic and nonvolcanic sites near the Sunset Crater volcano in northern Arizona. Focused field investigations were performed at this analog site to improve the understanding of natural and human-induced processes at Yucca Mountain, Nevada. The level of surface-disturbing activity was found to be the most influential factor affecting the measured airborne particle concentrations, which increased over three orders of magnitude relative to ambient conditions. As the surface-disturbing activity level increased, the particle size distribution and the majority of airborne particle mass shifted from particles with aerodynamic diameters less than 10 mum (0.00039 in) to particles with aerodynamic diameters greater than 10 mum (0.00039 in). Under ambient conditions, above average wind speeds tended to increase airborne particle concentrations. In contrast, stronger winds tended to decrease airborne particle concentrations in the breathing zone during light and heavy surface-disturbing conditions. A slight increase in the average airborne particle concentration during ambient conditions was found above older nonvolcanic deposits, which tended to be finer grained than the Sunset Crater tephra deposits. An increased airborne particle concentration was realized when walking on an extremely fine-grained deposit, but the sensitivity of airborne particle concentrations to the resuspendible fraction of near-surface grain mass was not conclusive in the field setting when human activities disturbed the bulk of near-surface material. Although the limited sample size precluded detailed statistical analysis, the differences in airborne particle

  2. Method for measuring the size distribution of airborne rhinovirus

    International Nuclear Information System (INIS)

    About 50% of viral-induced respiratory illnesses are caused by the human rhinovirus (HRV). Measurements of the concentrations and sizes of bioaerosols are critical for research on building characteristics, aerosol transport, and mitigation measures. We developed a quantitative reverse transcription-coupled polymerase chain reaction (RT-PCR) assay for HRV and verified that this assay detects HRV in nasal lavage samples. A quantitation standard was used to determine a detection limit of 5 fg of HRV RNA with a linear range over 1000-fold. To measure the size distribution of HRV aerosols, volunteers with a head cold spent two hours in a ventilated research chamber. Airborne particles from the chamber were collected using an Andersen Six-Stage Cascade Impactor. Each stage of the impactor was analyzed by quantitative RT-PCR for HRV. For the first two volunteers with confirmed HRV infection, but with mild symptoms, we were unable to detect HRV on any stage of the impactor

  3. Method for measuring the size distribution of airborne rhinovirus

    Energy Technology Data Exchange (ETDEWEB)

    Russell, M.L.; Goth-Goldstein, R.; Apte, M.G.; Fisk, W.J.

    2002-01-01

    About 50% of viral-induced respiratory illnesses are caused by the human rhinovirus (HRV). Measurements of the concentrations and sizes of bioaerosols are critical for research on building characteristics, aerosol transport, and mitigation measures. We developed a quantitative reverse transcription-coupled polymerase chain reaction (RT-PCR) assay for HRV and verified that this assay detects HRV in nasal lavage samples. A quantitation standard was used to determine a detection limit of 5 fg of HRV RNA with a linear range over 1000-fold. To measure the size distribution of HRV aerosols, volunteers with a head cold spent two hours in a ventilated research chamber. Airborne particles from the chamber were collected using an Andersen Six-Stage Cascade Impactor. Each stage of the impactor was analyzed by quantitative RT-PCR for HRV. For the first two volunteers with confirmed HRV infection, but with mild symptoms, we were unable to detect HRV on any stage of the impactor.

  4. Molecular composition and size distribution of sugars, sugar-alcohols and carboxylic acids in airborne particles during a severe urban haze event caused by wheat straw burning

    Science.gov (United States)

    Wang, Gehui; Chen, Chunlei; Li, Jianjun; Zhou, Bianhong; Xie, Mingjie; Hu, Shuyuan; Kawamura, Kimitaka; Chen, Yan

    2011-05-01

    Molecular compositions and size distributions of water-soluble organic compounds (WSOC, i.e., sugars, sugar-alcohols and carboxylic acids) in particles from urban air of Nanjing, China during a severe haze event caused by field burning of wheat straw were characterized and compared with those in the summer and autumn non-haze periods. During the haze event levoglucosan (4030 ng m -3) was the most abundant compound among the measured WSOC, followed by succinic acid, malic acid, glycerol, arabitol and glucose, being different from those in the non-haze samples, in which sucrose or azelaic acid showed a second highest concentration, although levoglucosan was the highest. The measured WSOC in the haze event were 2-20 times more than those in the non-hazy days. Size distribution results showed that there was no significant change in the compound peaks in coarse mode (>2.1 μm) with respect to the haze and non-haze samples, but a large difference in the fine fraction (glucose and related sugar-alcohols whose concentrations significantly increased in the fine haze samples are unclear. Compared to that in the fresh smoke particles of wheat straw burning an increase in relative abundance of succinic acid to levoglucosan during the haze event suggests a significant production of secondary organic aerosols during transport of the smoke plumes.

  5. Particle sizes from sectional data

    DEFF Research Database (Denmark)

    Pawlas, Zbynek; Nyengaard, Jens Randel; Jensen, Eva Bjørn Vedel

    2009-01-01

    We propose a new statistical method for obtaining information about particle size distributions from sectional data without specific assumptions about particle shape. The method utilizes recent advances in local stereology. We show how to estimate separately from sectional data the variance due to...... the local stereological estimation procedure and the variance due to the variability of particle sizes in the population. Methods for judging the difference between the distribution of estimated particle sizes and the distribution of true particle sizes are also provided....

  6. Toxicity to chicken embryos of organic extracts from airborne particulates separated into five sizes

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, H.

    1988-07-01

    The chicken embryo assay has been used for research on the toxicity of complex extracts derived from different environmental sources, as well as of individual compounds. However, only a few studies have been made on the toxicological effects of extracts derived from airborne particulate matter in chicken embryo. These studies showed that the toxic effect was due to the polycyclic aromatic hydrocarbons (PAHs) in the particles, although their structure and quantity were the factors determining the extent of the toxicity. Airborne particulate matter is composed of particles of different sizes, which can be separated into five classes according to their size by an Andersen high-volume sampler. Each class contained many kinds of compounds such as PAHs. In this study, airborne particulate matter was extracted according to particle size, the extracts analyzed for PAHs, and tested for embryotoxicity.

  7. Acoustic Resonator Optimisation for Airborne Particle Manipulation

    Science.gov (United States)

    Devendran, Citsabehsan; Billson, Duncan R.; Hutchins, David A.; Alan, Tuncay; Neild, Adrian

    Advances in micro-electromechanical systems (MEMS) technology and biomedical research necessitate micro-machined manipulators to capture, handle and position delicate micron-sized particles. To this end, a parallel plate acoustic resonator system has been investigated for the purposes of manipulation and entrapment of micron sized particles in air. Numerical and finite element modelling was performed to optimise the design of the layered acoustic resonator. To obtain an optimised resonator design, careful considerations of the effect of thickness and material properties are required. Furthermore, the effect of acoustic attenuation which is dependent on frequency is also considered within this study, leading to an optimum operational frequency range. Finally, experimental results demonstrated good particle levitation and capture of various particle properties and sizes ranging to as small as 14.8 μm.

  8. Evaluation of airborne particle emissions from commercial products containing carbon nanotubes

    International Nuclear Information System (INIS)

    The emission of the airborne particles from epoxy resin test sticks with different carbon nanotube (CNT) loadings and two commercial products were characterized while sanding with three grit sizes and three disk sander speeds. The total number concentrations, respirable mass concentrations, and particle size number/mass distributions of the emitted particles were measured using a condensation particle counter, an optical particle counter, and a scanning mobility particle sizer. The emitted particles were sampled on a polycarbonate filter and analyzed using electron microscopy. The highest number concentrations (arithmetic mean = 4,670 particles/cm3) were produced with coarse sandpaper, 2 % (by weight) CNT test sticks and medium disk sander speed, whereas the lowest number concentrations (arithmetic mean = 92 particles/cm3) were produced with medium sandpaper, 2 % CNT test sticks and slow disk sander speed. Respirable mass concentrations were the highest (arithmetic mean = 1.01 mg/m3) for fine sandpaper, 2 % CNT test sticks and medium disk sander speed and the lowest (arithmetic mean = 0.20 mg/m3) for medium sandpaper, 0 % CNT test sticks and medium disk sander speed. For CNT-epoxy samples, airborne particles were primarily micrometer-sized epoxy cores with CNT protrusions. No free CNTs were observed in airborne samples, except for tests conducted with 4 % CNT-epoxy. The number concentration, mass concentration, and size distribution of airborne particles generated when products containing CNTs are sanded depends on the conditions of sanding and the characteristics of the material being sanded.

  9. SIZE DISTRIBUTION AND RATE OF PRODUCTION OF AIRBORNE PARTICULATE MATTER GENERATED DURING METAL CUTTING

    International Nuclear Information System (INIS)

    During deactivation and decommissioning activities, thermal cutting tools, such as plasma torch, laser, and gasoline torch, are used to cut metals. These activities generate fumes, smoke and particulates. These airborne species of matter, called aerosols, may be inhaled if suitable respiratory protection is not used. Inhalation of the airborne metallic aerosols has been reported to cause ill health effects, such as acute respiratory syndrome and chromosome damage in lymphocytes. In the nuclear industry, metals may be contaminated with radioactive materials. Cutting these metals, as in size reduction of gloveboxes and tanks, produces high concentrations of airborne transuranic particles. Particles of the respirable size range (size < 10 microm) deposit in various compartments of the respiratory tract, the fraction and the site in the respiratory tract depending on the size of the particles. The dose delivered to the respiratory tract depends on the size distribution of the airborne particulates (aerosols) and their concentration and radioactivity/toxicity. The concentration of airborne particulate matter in an environment is dependent upon the rate of their production and the ventilation rate. Thus, measuring aerosol size distribution and generation rate is important for (1) the assessment of inhalation exposures of workers, (2) the selection of respiratory protection equipment, and (3) the design of appropriate filtration systems. Size distribution of the aerosols generated during cutting of different metals by plasma torch was measured. Cutting rates of different metals, rate of generation of respirable mass, as well as the fraction of the released kerf that become respirable were determined. This report presents results of these studies. Measurements of the particles generated during cutting of metal plates with a plasma arc torch revealed the presence of particles with mass median aerodynamic diameters of particles close to 0.2 micro

  10. Size distribution and chemical composition of airborne particles in south-eastern Finland during different seasons and wildfire episodes in 2006

    International Nuclear Information System (INIS)

    The inorganic main elements, trace elements and PAHs were determined from selected PM1, PM2.5 and PM10 samples collected at the Nordic background station in Virolahti during different seasons and during the wildfire episodes in 2006. Submicron particles are those most harmful to human beings, as they are able to penetrate deep into the human respiratory system and may cause severe health effects. About 70-80%, of the toxic trace elements, like lead, cadmium, arsenic and nickel, as well as PAH compounds, were found in particles smaller than 1 μm. Furthermore, the main part of the copper, zinc, and vanadium was associated with submicron particles. In practice, all the PAHs found in PM10 were actually in PM2.5. For PAHs and trace elements, it is more beneficial to analyse the PM2.5 or even the PM1 fraction instead of PM10, because exclusion of the large particles reduces the need for sample cleaning to minimize the matrix effects during the analysis. During the wildfire episodes, the concentrations of particles smaller than 2.5 μm, as well as those of submicron particles, increased, and also the ratio PM1/PM10 increased to about 50%. On the fire days, the mean potassium concentration was higher in all particle fractions, but ammonium and nitrate concentrations rose only in particles smaller than 1.0 μm. PAH concentrations rose even to the same level as in winter.

  11. Discussion on National Standard GB 6167 "Methods for Testing the Performance of Airborne Particle Counter"

    Institute of Scientific and Technical Information of China (English)

    刘俊杰; 朱能; 王君山

    2003-01-01

    Airborne particle counters are used widely to test the air cleanliness of cleanrooms. The current Chinese national standard of airborne particle counter calibration, GB6167-85, Methods for Testing the Performance of Dust Particle Counter, has kept the same for more than 10 years. It is necessary to be amended in time.This paper discusses the differences between Chinese airborne particle counter calibration procedure and other new calibration procedures in other countries, and points out the defects of current Chinese national standard.The draft of revised Chinese National Standard is also introduced. The new revised standard, Methods for Testing the Performance of Airborne Particle Counter, covers two level calibrations:primary and secondary. Primary calibration procedure includes testing 6 kinds of performances: sample airflow rate, false counting, particle size accuracy and resolution, particle counting stability, counting efficiency and particle concentration limit. Secondary calibration is a relative comparing test method to verify the counting accuracy of calibrated airborne particle counters. Finally, how to keep the calibration traceability is suggested.

  12. Bioaerosol Mass Spectrometry for Rapid Detection of Individual Airborne Mycobacterium tuberculosis H37Ra Particles

    OpenAIRE

    Tobias, Herbert J.; Schafer, Millie P.; Pitesky, Maurice; Fergenson, David P.; Horn, Joanne; Frank, Matthias; Gard, Eric E.

    2005-01-01

    Single-particle laser desorption/ionization time-of-flight mass spectrometry, in the form of bioaerosol mass spectrometry (BAMS), was evaluated as a rapid detector for individual airborne, micron-sized, Mycobacterium tuberculosis H37Ra particles, comprised of a single cell or a small number of clumped cells. The BAMS mass spectral signatures for aerosolized M. tuberculosis H37Ra particles were found to be distinct from M. smegmatis, Bacillus atrophaeus, and B. cereus particles, using a distin...

  13. Airborne particle monitoring with urban closed-circuit television camera networks and a chromatic technique

    International Nuclear Information System (INIS)

    An economic approach for the preliminary assessment of 2–10 µm sized (PM10) airborne particle levels in urban areas is described. It uses existing urban closed-circuit television (CCTV) surveillance camera networks in combination with particle accumulating units and chromatic quantification of polychromatic light scattered by the captured particles. Methods for accommodating extraneous light effects are discussed and test results obtained from real urban sites are presented to illustrate the potential of the approach

  14. Can airborne ultrasound monitor bubble size in chocolate?

    International Nuclear Information System (INIS)

    Aerated chocolate products consist of solid chocolate with the inclusion of bubbles and are a popular consumer product in many countries. The volume fraction and size distribution of the bubbles has an effect on their sensory properties and manufacturing cost. For these reasons it is important to have an online real time process monitoring system capable of measuring their bubble size distribution. As these products are eaten by consumers it is desirable that the monitoring system is non contact to avoid food contaminations. In this work we assess the feasibility of using an airborne ultrasound system to monitor the bubble size distribution in aerated chocolate bars. The experimental results from the airborne acoustic experiments were compared with theoretical results for known bubble size distributions using COMSOL Multiphysics. This combined experimental and theoretical approach is used to develop a greater understanding of how ultrasound propagates through aerated chocolate and to assess the feasibility of using airborne ultrasound to monitor bubble size distribution in these systems. The results indicated that a smaller bubble size distribution would result in an increase in attenuation through the product

  15. Can airborne ultrasound monitor bubble size in chocolate?

    Science.gov (United States)

    Watson, N.; Hazlehurst, T.; Povey, M.; Vieira, J.; Sundara, R.; Sandoz, J.-P.

    2014-04-01

    Aerated chocolate products consist of solid chocolate with the inclusion of bubbles and are a popular consumer product in many countries. The volume fraction and size distribution of the bubbles has an effect on their sensory properties and manufacturing cost. For these reasons it is important to have an online real time process monitoring system capable of measuring their bubble size distribution. As these products are eaten by consumers it is desirable that the monitoring system is non contact to avoid food contaminations. In this work we assess the feasibility of using an airborne ultrasound system to monitor the bubble size distribution in aerated chocolate bars. The experimental results from the airborne acoustic experiments were compared with theoretical results for known bubble size distributions using COMSOL Multiphysics. This combined experimental and theoretical approach is used to develop a greater understanding of how ultrasound propagates through aerated chocolate and to assess the feasibility of using airborne ultrasound to monitor bubble size distribution in these systems. The results indicated that a smaller bubble size distribution would result in an increase in attenuation through the product.

  16. Radioactive airborne particles from Chernobyl forest fires

    International Nuclear Information System (INIS)

    The spring and summer, 1992 within 30-km zone near Chernobyl NPP were very hot and dry. That lead to forest fires in May (4 ... 9,23 ... 25), July (28 ... 30) and August (10...12). The Cs-137 soil contamination density (SCD) was equal to 1...400 Ci/km2 at various forest sections of combustion. The stationary air samplers with capacity of 1500 m3/h were used for the monitoring of aerosol emissions during fires. These samplers were situated at a distance of 5...10km from fires boundaries. Smoke particles were collected by the fibrous filters FPP-15-1,5 (Russia). After exposure the activity of aerosols of Cs which deposited by a filter was measured by a gamma-spectrometer. For the separation of Sr-90 and isotopes of Pu the radiochemical analysis was used. It was found that the concentration of Cs-137 increased up to 10...100 times compare with open-quotes backgroundclose quotes one even at several km from fires. The concentration of Cs-137 inside of combustion zone was estimated could exceed the Russian maximum permissible one both for population (0.49 nCi/m3) and for professionals (14 nCi/m3) if the SCD will be more than 0.5 and 7 Ci/km2, respectively. It was measured that Cs-137/Sr-90 and Cs-137/Pu-238 ratios increase in fire emissions. It is obviously, that such enrichment was a consequense of radioactive cesium evaporation at temperature more than 500 C. The experimental forest fire was carry out in August, 1993 in Bryansk region (Russia). The forest section with area 50x50 m was selected. The SCD of Cs-137 was equal to 30 Ci/km2. The Cs-137 concentration during the day before the experiment was equal to 0.16pCi/m3. The concentration was varied from 1.6 to 15 pCi/m3 during the experiment. For the determination of particle sizes the filter pack technique (Budyka et al, 1993) was used. It was found that particle size distribution was a bimodal in plume

  17. Concentration and size distribution of total airborne microbes in hazy and foggy weather.

    Science.gov (United States)

    Dong, Lijie; Qi, Jianhua; Shao, Congcong; Zhong, Xi; Gao, Dongmei; Cao, Wanwan; Gao, Jiawei; Bai, Ran; Long, Gaoyuan; Chu, Congcong

    2016-01-15

    Atmospheric bioaerosol particles were collected using a bioaerosol sampler from Oct. 2013 to Aug. 2014 in the coastal region of Qingdao. The total microbes were measured using an epifluorescence microscope after staining with DAPI (4',6-diamidino-2-phenylindole). The concentration of total airborne microbes showed seasonal variation, with the highest value in winter and the lowest in summer. The mean concentration of total microbes was 6.55 × 10(5)Cells/m(3) on non-hazy days. The total microbe concentration increased to 7.09 × 10(5) and 9.00 × 10(5)Cells/m(3) on hazy and foggy days, respectively. The particle sizes of the total microbes presented a bimodal distribution on sunny days, with one peak at 1.1-2.1 μm and another at 4.7-7.0 μm. The size distribution of total microbes showed an increase in the fine fraction on hazy days and an increase in the coarse fraction on foggy days. However, the size distribution became unimodal during a heating period. Spearman correlation analysis showed that temperature and O3 had a significant negative correlation with the airborne microbe concentration, while PM2.5, SO2, NO2, CO and the air quality index (AQI) had significant positive correlations with the airborne microbe concentration during hazy days. The increased number of airborne microbes will affect the air quality on hazy days. PMID:26473703

  18. Endotoxin in Size-Separated Metal Working Fluid Aerosol Particles.

    Science.gov (United States)

    Dahlman-Höglund, Anna; Lindgren, Åsa; Mattsby-Baltzer, Inger

    2016-08-01

    Patients with airway symptoms working in metal working industries are increasing, despite efforts to improve the environmental air surrounding the machines. Our aim was to analyse the amount of endotoxin in size-separated airborne particles of metal working fluid (MWF) aerosol, by using the personal sampler Sioutas cascade impactor, to compare filter types, and to compare the concentration of airborne endotoxin to that of the corresponding MWFs. In a pilot field study, aerosols were collected in two separate machine halls on totally 10 occasions, using glass fibre and polytetrafluoroethylene (PTFE) filters in parallel at each station. Airborne endotoxin was distributed over all size fractions. While a major part was found in the largest size fraction (72%, 2.5-10 µm), up to 8% of the airborne endotoxin was detected in the smallest size fraction (efficiency of the filter types, a significantly higher median endotoxin level was found with glass fibres filters collecting the largest particle-size fraction (1.2-fold) and with PTFE filters collecting the smallest ones (5-fold). The levels of endotoxin in the size-separated airborne particle fractions correlated to those of the MWFs supporting the aerosol-generating machines. Our study indicates that a significant part of inhalable aerosols of MWFs consists of endotoxin-containing particles below the size of intact bacteria, and thus small enough to readily reach the deepest part of the lung. Combined with other chemical irritants of the MWF, exposure to MWF aerosols containing endotoxin pose a risk to respiratory health problems. PMID:27268595

  19. On Airborne Wear Particles Emissions ofCommercial Disc Brake Materials– A Pin on Disc Simulation

    OpenAIRE

    Söderberg, Anders; Wahlström, Jens; Olander, Lars; Jansson, Anders; Olofsson, Ulf

    2008-01-01

    A novel test method was used to study the concentration and size distribution of airborne wear particles from disc brake materials. A pin-on-disc tribometer equipped with particle counting instruments was used as test equipment. Four different nonasbestoses-organic (NAO) linings for the U.S. market and four different low metallic linings for the EU market were tested against material from gray cast iron rotors. The result indicates that the low metallic linings are more aggressive to the roto...

  20. [Investigation of Carbonaceous Airborne Particles by Scanning Proton Microprobe].

    Science.gov (United States)

    Bao, Liang-man; Liu, Jiang-feng; Lei, Qian-tao; Li, Xiao-lin; Zhang, Gui-lin; Li, Yan

    2016-01-15

    Carbonaceous particles are an important component of the atmospheric aerosol particles and important for global climate change, air quality and human health. The PM₁₀ single particles from two environmental monitor locations and seven pollution emission sources were analyzed using scanning proton microprobe (SPM) techniques. The concentration of carbon in individual particles was quantitatively determined by proton non-Rutherford elastic backscattering spectrometry (EBS). The results of this investigation showed that carbonaceous particles were dominant in the pollution sources of coal and oil combustions, diesel busexhaust and automobile exhaust, while inorganic particles were dominant in the sources of steel industry, cement dust and soil dust. Carbonaceous matter was enriched in particles from the city center, while mineral matter was the main component of airborne particles in the industrial area. Elemental mapping of single aerosol particles yielded important information on the chemical reactions of aerosol particles. The micro-PIXE (particle induced X-ray emission) maps of S, Ca and Fe of individual carbonaceous particles showed that sulfuration reaction occurred between SO₂and mineral particles, which increased the sulfur content of particles. PMID:27078933

  1. Characterization of winter airborne particles at Emperor Qin's Terra-cotta Museum, China

    International Nuclear Information System (INIS)

    Daytime and nighttime total suspended particulate matters (TSP) were collected inside and outside Emperor Qin's Terra-cotta Museum, the most popular on-site museum in China, in winter 2008. The purpose of this study was to investigate the contribution of visitors to indoor airborne particles in two display halls with different architectural and ventilating conditions, including Exhibition Hall and Pit No.1. Morphological and elemental analyses of 7-day individual particle samples were performed with scanning electron microscopy and energy dispersive X-ray spectrometer (SEM-EDX). Particle mass concentrations in Exhibition Hall and Pit No.1 were in a range of 54.7-291.7 μg m-3 and 95.3-285.4 μg m-3 with maximum diameters of 17.5 μm and 26.0 μm, respectively. In most sampling days, daytime/nighttime particle mass ratios in Exhibition Hall (1.30-3.12) were higher than those in Pit No.1 (0.96-2.59), indicating more contribution of the tourist flow in Exhibition Hall than in Pit No. 1. The maximum of particle size distributions were in a range of 0.5-1.0 μm, with the highest abundance (43.4%) occurred in Exhibition Hall at night. The majority of airborne particles at the Museum was composed of soil dust, S-containing particles, and low-Z particles like soot aggregate and biogenic particles. Both size distributions and particle types were found to be associated with visitor numbers in Exhibition Hall and with natural ventilation in Pit No.1. No significant influence of visitors on indoor temperature and relative humidity (RH) was found in either display halls. Those baseline data on the nature of the airborne particles inside the Museum can be incorporated into the maintenance criteria, display management, and ventilation strategy by conservators of the museum.

  2. New Methods for Personal Exposure Monitoring for Airborne Particles.

    Science.gov (United States)

    Koehler, Kirsten A; Peters, Thomas M

    2015-12-01

    Airborne particles have been associated with a range of adverse cardiopulmonary outcomes, which has driven its monitoring at stationary central sites throughout the world. Individual exposures, however, can differ substantially from concentrations measured at central sites due to spatial variability across a region and sources unique to the individual, such as cooking or cleaning in homes, traffic emissions during commutes, and widely varying sources encountered at work. Personal monitoring with small, battery-powered instruments enables the measurement of an individual's exposure as they go about their daily activities. Personal monitoring can substantially reduce exposure misclassification and improve the power to detect relationships between particulate pollution and adverse health outcomes. By partitioning exposures to known locations and sources, it may be possible to account for variable toxicity of different sources. This review outlines recent advances in the field of personal exposure assessment for particulate pollution. Advances in battery technology have improved the feasibility of 24-h monitoring, providing the ability to more completely attribute exposures to microenvironment (e.g., work, home, commute). New metrics to evaluate the relationship between particulate matter and health are also being considered, including particle number concentration, particle composition measures, and particle oxidative load. Such metrics provide opportunities to develop more precise associations between airborne particles and health and may provide opportunities for more effective regulations. PMID:26385477

  3. Inversely tracking indoor airborne particles to locate their release sources

    Science.gov (United States)

    Zhang, Tengfei (Tim); Li, Hongzhu; Wang, Shugang

    2012-08-01

    Airborne particles can have numerous adverse effects on human health. Knowing the release locations of airborne particulate sources is helpful in minimizing pollutant exposure. This paper describes a proposal to locate indoor particulate sources by two inverse models: the quasi-reversibility (QR) model and the zone prescription of contaminant sources with the Lagrangian-reversibility (LR) model. The QR model reverses the time marching direction of the Eulerian governing equation and replaces the second-order diffusion term with a fourth-order stabilization term. The zone prescription LR model traces individual particulate motion in a Lagrangian reference frame after reversing the flow field. The particle trajectories are solved backward to the initial release once the conservative forces acting on particles are reversed. The tracked particles are proposed to be placed at the zone boundary of the largest concentration contour within the domain at a given time, which is provided as the initially known information. By connecting all particles at t = 0, a zone is formed that can prescribe the actual contaminant source. This study finds that both models can accurately locate particulate sources released instantaneously at a spot. The QR model performs slightly better than the LR model but is much more computationally demanding.

  4. Identifying airborne metal particles sources near an optoelectronic and semiconductor industrial park

    Science.gov (United States)

    Chen, Ho-Wen; Chen, Wei-Yea; Chang, Cheng-Nan; Chuang, Yen-Hsun; Lin, Yu-Hao

    2016-06-01

    The recently developed Central Taiwan Science Park (CTSP) in central Taiwan is home to an optoelectronic and semiconductor industrial cluster. Therefore, exploring the elemental compositions and size distributions of airborne particles emitted from the CTSP would help to prevent pollution. This study analyzed size-fractionated metal-rich particle samples collected in upwind and downwind areas of CTSP during Jan. and Oct. 2013 by using micro-orifice uniform deposited impactor (MOUDI). Correlation analysis, hierarchical cluster analysis and particle mass-size distribution analysis are performed to identify the source of metal-rich particle near the CTSP. Analyses of elemental compositions and particle size distributions emitted from the CTSP revealed that the CTSP emits some metals (V, As, In Ga, Cd and Cu) in the ultrafine particles (pollution index for optoelectronic and semiconductor emission in the CTSP. Meanwhile, the ratios of As/Ga concentration at the particle size of 0.32 μm demonstrates that humans near the CTSP would be potentially exposed to GaAs ultrafine particles. That is, metals such as Ga and As and other metals that are not regulated in Taiwan are potentially harmful to human health.

  5. Concentrations and Sources of Airborne Particles in a Neonatal Intensive Care Unit

    Science.gov (United States)

    Licina, Dusan; Bhangar, Seema; Brooks, Brandon; Baker, Robyn; Firek, Brian; Tang, Xiaochen; Morowitz, Michael J.; Banfield, Jillian F.; Nazaroff, William W.

    2016-01-01

    Premature infants in neonatal intensive care units (NICUs) have underdeveloped immune systems, making them susceptible to adverse health consequences from air pollutant exposure. Little is known about the sources of indoor airborne particles that contribute to the exposure of premature infants in the NICU environment. In this study, we monitored the spatial and temporal variations of airborne particulate matter concentrations along with other indoor environmental parameters and human occupancy. The experiments were conducted over one year in a private-style NICU. The NICU was served by a central heating, ventilation and air-conditioning (HVAC) system equipped with an economizer and a high-efficiency particle filtration system. The following parameters were measured continuously during weekdays with 1-min resolution: particles larger than 0.3 μm resolved into 6 size groups, CO2 level, dry-bulb temperature and relative humidity, and presence or absence of occupants. Altogether, over sixteen periods of a few weeks each, measurements were conducted in rooms occupied with premature infants. In parallel, a second monitoring station was operated in a nearby hallway or at the local nurses’ station. The monitoring data suggest a strong link between indoor particle concentrations and human occupancy. Detected particle peaks from occupancy were clearly discernible among larger particles and imperceptible for submicron (0.3–1 μm) particles. The mean indoor particle mass concentrations averaged across the size range 0.3–10 μm during occupied periods was 1.9 μg/m3, approximately 2.5 times the concentration during unoccupied periods (0.8 μg/m3). Contributions of within-room emissions to total PM10 mass in the baby rooms averaged 37–81%. Near-room indoor emissions and outdoor sources contributed 18–59% and 1–5%, respectively. Airborne particle levels in the size range 1–10 μm showed strong dependence on human activities, indicating the importance of indoor

  6. Concentrations and Sources of Airborne Particles in a Neonatal Intensive Care Unit.

    Directory of Open Access Journals (Sweden)

    Dusan Licina

    Full Text Available Premature infants in neonatal intensive care units (NICUs have underdeveloped immune systems, making them susceptible to adverse health consequences from air pollutant exposure. Little is known about the sources of indoor airborne particles that contribute to the exposure of premature infants in the NICU environment. In this study, we monitored the spatial and temporal variations of airborne particulate matter concentrations along with other indoor environmental parameters and human occupancy. The experiments were conducted over one year in a private-style NICU. The NICU was served by a central heating, ventilation and air-conditioning (HVAC system equipped with an economizer and a high-efficiency particle filtration system. The following parameters were measured continuously during weekdays with 1-min resolution: particles larger than 0.3 μm resolved into 6 size groups, CO2 level, dry-bulb temperature and relative humidity, and presence or absence of occupants. Altogether, over sixteen periods of a few weeks each, measurements were conducted in rooms occupied with premature infants. In parallel, a second monitoring station was operated in a nearby hallway or at the local nurses' station. The monitoring data suggest a strong link between indoor particle concentrations and human occupancy. Detected particle peaks from occupancy were clearly discernible among larger particles and imperceptible for submicron (0.3-1 μm particles. The mean indoor particle mass concentrations averaged across the size range 0.3-10 μm during occupied periods was 1.9 μg/m3, approximately 2.5 times the concentration during unoccupied periods (0.8 μg/m3. Contributions of within-room emissions to total PM10 mass in the baby rooms averaged 37-81%. Near-room indoor emissions and outdoor sources contributed 18-59% and 1-5%, respectively. Airborne particle levels in the size range 1-10 μm showed strong dependence on human activities, indicating the importance of indoor

  7. COMPARISON OF VARIOUS PARTICLE SIZING TECHNIQUES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    SEM,TEM,gas adsorption,X-ray Sedigraph and laser particle sizing have been employed to analyse particle size distribution and powder agglomeration for Alcoa A16 and for Sumitomo AKS-53B and SKP-53 α-Al2O3 powders on several occasions as well.Comparison and evaluation of various particle-sizing techniques have been made.

  8. Microvolumetric determination of inorganic and organic sulphur in airborne particles

    Energy Technology Data Exchange (ETDEWEB)

    Moehnle, K.; Krivan, V.; Grallath, E.

    1984-02-01

    A reductive procedure for the determination of sulphur was modified and applied to the analysis of airborne particles. It is based on the reduction of the given sulphur forms with the mixture HI/HCOOH/H/sub 3/PO/sub 2//Sb/sub 2/O/sub 3/ to hydrogen sulphide, which is transferred into a NaOH solution and determined by microtitration with Cd/sup 2 +/ using dithizone as indicator. Examination of the behaviour of the different sulphur forms in the reduction mixture showed that the inorganic sulphur was converted to H/sub 2/S whereas the organic remained in the reaction flask. This makes possible the differentiation between inorganic and organic sulphur when one part of the sample is directly reacted with the mixture and the other one is oxidatively decomposed (Schoeniger), and then the total sulphur determined with the same procedure. The method was used for the analysis of a number of airborne particle samples of different origin, and the results were compared with those of some instrumental techniques.

  9. Use of GSR particle analysis program on an analytical SEM to identify sources of emission of airborne particles

    International Nuclear Information System (INIS)

    Full text: High concentrations of airborne particles, in particular PM10 (particulate matter 10, but has been little used in Australia for airborne particulates. Two sets of 15 mm PM10 samples were collected in March and April 2000 from two sites in Brisbane, one within a suburb and one next to an arterial road. The particles were collected directly onto double-sided carbon tapes with a cascade impactor attached to a high-volume PM10 sampler. The carbon tapes were analysed in a JEOL 840 SEM equipped with a Be-window energy-dispersive X-ray detector and Moran Scientific microanalysis system. An automated Gun Shot Residue (GSR) program was used together with backscattered electron imaging to characterise and analyse individual particulates. About 6,000 particles in total were analysed for each set of impactor samples. Due to limitations of useful pixel size, only particles larger than about 0.5 μm could be analysed. The size, shape and estimated elemental composition (from Na to Pb) of the particles were subjected to non-hierarchical cluster analysis and the characteristics of the clusters were related to their possible sources of emission. Both samples resulted in similar particle clusters. The particles could be classified into three main categories non-spherical (58% of the total number of analysed particles, shape factor >1 1), spherical (15%) and 'carbonaceous' (27%, ie with unexplained % of elemental mass >75%). Non-spherical particles were mainly sea salt and soil particles, and a small amount of iron, lead and mineral dust. The spherical particles were mainly sea salt particles and flyash, and a small amount of iron, lead and secondary sulphate dust. The carbonaceous particles included carbon material mixed with secondary aerosols, roadside dust, sea salt or industrial dust. The arterial road sample also contained more roadside dust and less secondary aerosols than the suburb sample. Current limitations with this method are the minimum particle size

  10. Characterization and Control of Airborne Particles Emitted During Production of Epoxy / Carbon Nanotube Nanocomposites

    Science.gov (United States)

    Cena, Lorenzo G.; Peters, Thomas M.

    2016-01-01

    This work characterized airborne particles that were generated from the weighing of bulk, multi-wall carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. It also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood, and biosafety cabinet) for control of particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable mass concentrations were measured using an optical particle counter (OPC) and a condensation particle counter (CPC), and particle morphology was assessed by transmission electron microscopy. The ratios of the geometric mean (GM) concentrations measured during the process to that measured in the background (P/B ratios) were used as indices of the impact of the process and the LEVs on observed concentrations. Processing CNT-epoxy nanocomposites materials released respirable size airborne particles (P/B ratio: weighing = 1.79; sanding = 5.90) but generally no nanoparticles (P/B ratiô1). The particles generated during sanding were predominately micron-sized with protruding CNTs and very different from bulk CNTs that tended to remain in large (>1 μm) tangled clusters. Respirable mass concentrations in the operator’s breathing zone were lower when sanding was performed in the biological safety cabinet (GM = 0.20 μg/m3) compared to those with no LEV (GM = 2.68 μg/m3) or those when sanding was performed inside the fume hood (GM = 21.4 μg/m3; p-value < 0.0001). The poor performance of the custom fume hood used in this study may have been exacerbated by its lack of a front sash and rear baffles and its low face velocity (0.39 m/sec). PMID:21253981

  11. Laboratory testing of airborne brake wear particle emissions using a dynamometer system under urban city driving cycles

    Science.gov (United States)

    Hagino, Hiroyuki; Oyama, Motoaki; Sasaki, Sousuke

    2016-04-01

    To measure driving-distance-based mass emission factors for airborne brake wear particulate matter (PM; i.e., brake wear particles) related to the non-asbestos organic friction of brake assembly materials (pads and lining), and to characterize the components of brake wear particles, a brake wear dynamometer with a constant-volume sampling system was developed. Only a limited number of studies have investigated brake emissions under urban city driving cycles that correspond to the tailpipe emission test (i.e., JC08 or JE05 mode of Japanese tailpipe emission test cycles). The tests were performed using two passenger cars and one middle-class truck. The observed airborne brake wear particle emissions ranged from 0.04 to 1.4 mg/km/vehicle for PM10 (particles up to 10 μm (in size), and from 0.04 to 1.2 mg/km/vehicle for PM2.5. The proportion of brake wear debris emitted as airborne brake wear particles was 2-21% of the mass of wear. Oxygenated carbonaceous components were included in the airborne PM but not in the original friction material, which indicates that changes in carbon composition occurred during the abrasion process. Furthermore, this study identified the key tracers of brake wear particles (e.g., Fe, Cu, Ba, and Sb) at emission levels comparable to traffic-related atmospheric environments.

  12. Airborne brake wear debris: size distributions, composition, and a comparison of dynamometer and vehicle tests.

    Science.gov (United States)

    Sanders, Paul G; Xu, Ning; Dalka, Tom M; Maricq, M Matti

    2003-09-15

    Particle size distributions of light-duty vehicle brake wear debris are reported with careful attention paid to avoid sampling biases. Electrical low-pressure impactor and micro-orifice uniform deposit impactor measurements yield consistent size distributions, and the net particulate matter mass from each method is in good agreement with gravimetric filter measurements. The mass mean diameter of wear debris from braking events representative of urban driving is 6 microm, and the number-weighted mean is 1-2 microm for three currently used classes of lining materials: low metallic, semimetallic, and non-asbestos organic (NAO). In contrast, the wear rates are very material dependent, both in number and mass of particles, with 3-4 times higher emissions observed from the low metallic linings as compared to the semimetallic and NAO linings. Wind tunnel and test track measurements demonstrate the appearance of micron size particles that correlate with braking events, with approximately 50% of the wear debris being airborne for the test vehicle in this study. Elemental analysis of the wear debris reveals a consistent presence of the elements Fe, Cu, and Ba in both dynamometer and test track samples. PMID:14524436

  13. A review of methods for sampling large airborne particles and associated radioactivity

    International Nuclear Information System (INIS)

    Radioactive particles, tens of μm or more in diameter, are unlikely to be emitted directly from nuclear facilities with exhaust gas cleansing systems, but may arise in the case of an accident or where resuspension from contaminated surfaces is significant. Such particles may dominate deposition and, according to some workers, may contribute to inhalation doses. Quantitative sampling of large airborne particles is difficult because of their inertia and large sedimentation velocities. The literature describes conditions for unbiased sampling and the magnitude of sampling errors for idealised sampling inlets in steady winds. However, few air samplers for outdoor use have been assessed for adequacy of sampling. Many size selective sampling methods are found in the literature but few are suitable at the low concentrations that are often encountered in the environment. A number of approaches for unbiased sampling of large particles have been found in the literature. Some are identified as meriting further study, for application in the measurement of airborne radioactivity. (author)

  14. A microfluidics-based on-chip impinger for airborne particle collection.

    Science.gov (United States)

    Mirzaee, I; Song, M; Charmchi, M; Sun, H

    2016-06-21

    Capturing airborne particles from air into a liquid is a critical process for the development of many sensors and analytical systems. A miniaturized airborne particle sampling device (microimpinger) has been developed in this research. The microimpinger relies on a controlled bubble generation process produced by driving air through microchannel arrays. The particles confined in the microscale bubbles are captured in the sampling liquid while the bubbles form, are released and travel in a millimetre-scale sealed liquid reservoir. The microchannel arrays in the impinger are fabricated using a soft-lithography method with polydimethylsiloxane (PDMS) as the structural material. To prevent air leakage at the connections, a PDMS-only sealing technique is successfully developed. The hydrophobicity of the microchannel surface is found to be critical for generating continuous and stable bubbles in the bubbling process. A Teflon layer is coated on the walls of a microchannel array by vapor deposition which effectively increases the hydrophobicity of the PDMS. The collection efficiency of the microimpinger is measured by counting different sizes of fluorescent polystyrene latex particles on polycarbonate membrane filters. Collection efficiencies above 90% are achieved. Furthermore, the particle capturing mechanisms during the injection, formation and rise of a single microbubble are investigated by a computational fluid dynamics (CFD) model. The Navier-Stokes equations are solved along with the use of the volume-of-fluid (VOF) method to capture the bubble deformations and the particles are tracked using a Lagrangian equation of motion. The model is also employed to study the effect of bubble size on the collection efficiency of the microimpinger. PMID:27185303

  15. Determination of chemical composition of individual airborne particles by SEM/EDX and micro-Raman spectrometry: A review

    Science.gov (United States)

    Stefaniak, E. A.; Buczynska, A.; Novakovic, V.; Kuduk, R.; Van Grieken, R.

    2009-04-01

    The strategies for sampling and analysis by SEM/EDX and micro-Raman spectrometry for individual airborne particles analysis as applied at the University of Antwerp (Belgium) by the MITAC group have been reviewed. Microbeam techniques provide detailed information concerning the origin, formation, transport, reactivity, transformation reactions and environmental impact of particulate matter. Moreover, some particles of certain chemical properties have been recognized as a threat for human health and cultural heritage objects. However, the small sizes of particles result in specific problems with respect to single particle analysis. Development of equipment and software for improvement of analysis and quantification are reported.

  16. Particle size characterization by ultrasonic attenuation spectra

    Institute of Scientific and Technical Information of China (English)

    Mingxu Su; Minghua Xue; Xiaoshu Cai; Zhitao Shang; Feng Xu

    2008-01-01

    This paper contributes to extracting information from signals of broadband ultrasonic attenuation spectrum for effective utilization in particle size characterization. The single particle scattering model and the coupled-phase model are formulated simultaneously, the relationship between particle size distribution and ultrasonic spectrum is established, and a convergence criterion for calculation is quantified. Demonsa'ation inversion by the optimum regularization factor method is carded out to yield typical numerical results for discussion. With the experimental set-up developed by the Institute of Particle and Two-Phase Flow Measurement (IPTFM) at the University of Shanghai for Science and Technology, sand sediment particle size is measured by attenuation spectrum and analyzed using the above inversion algorithm and theoretical models. To validate the proposed ultrasonic spectrum particle sizing method, results are compared with those obtained by microscopy.

  17. Particle size distribution instrument. Topical report 13

    Energy Technology Data Exchange (ETDEWEB)

    Okhuysen, W.; Gassaway, J.D.

    1995-04-01

    The development of an instrument to measure the concentration of particles in gas is described in this report. An in situ instrument was designed and constructed which sizes individual particles and counts the number of occurrences for several size classes. Although this instrument was designed to detect the size distribution of slag and seed particles generated at an experimental coal-fired magnetohydrodynamic power facility, it can be used as a nonintrusive diagnostic tool for other hostile industrial processes involving the formation and growth of particulates. Two of the techniques developed are extensions of the widely used crossed beam velocimeter, providing simultaneous measurement of the size distribution and velocity of articles.

  18. An introduction to data analysis of airborne particle composition

    International Nuclear Information System (INIS)

    A major problem facing air quality management personnel is the identification of sources of airborne particles and the quantitative apportionment of the aerosol mass to those sources. The ability to collect particle samples and analyze these samples for a suite of elements by such techniques as neutron activation analysis or x-ray fluorescence provides that data for the problem of resolving a series of complex mixtures into its components based on the profiles of the elements emitted by the various sources in the airshed. If all of the sources and their composition profiles are known, then the mass balance model becomes a multiple regression problem. If a series of samples have been analyzed without substantial information being available on the sources, factor analysis methods can be employed. In both situations, there are limits to the identification of specific sources or the location of the sources. Thus, other methods that combine chemical with meteorological data have been developed to assist in spatial identification of pollutant sources. There are also limitations to the ability of any statistical method to resolve sources in real world problems. The physical and statistical basis of these methods and their application to representative problems are reviewed in this report. (author). 42 refs, 5 figs, 5 tabs

  19. Size-resolved culturable airborne bacteria sampled in rice field, sanitary landfill, and waste incineration sites.

    Science.gov (United States)

    Heo, Yongju; Park, Jiyeon; Lim, Sung-Il; Hur, Hor-Gil; Kim, Daesung; Park, Kihong

    2010-08-01

    Size-resolved bacterial concentrations in atmospheric aerosols sampled by using a six stage viable impactor at rice field, sanitary landfill, and waste incinerator sites were determined. Culture-based and Polymerase Chain Reaction (PCR) methods were used to identify the airborne bacteria. The culturable bacteria concentration in total suspended particles (TSP) was found to be the highest (848 Colony Forming Unit (CFU)/m(3)) at the sanitary landfill sampling site, while the rice field sampling site has the lowest (125 CFU/m(3)). The closed landfill would be the main source of the observed bacteria concentration at the sanitary landfill. The rice field sampling site was fully covered by rice grain with wetted conditions before harvest and had no significant contribution to the airborne bacteria concentration. This might occur because the dry conditions favor suspension of soil particles and this area had limited personnel and vehicle flow. The respirable fraction calculated by particles less than 3.3 mum was highest (26%) at the sanitary landfill sampling site followed by waste incinerator (19%) and rice field (10%), which showed a lower level of respiratory fraction compared to previous literature values. We identified 58 species in 23 genera of culturable bacteria, and the Microbacterium, Staphylococcus, and Micrococcus were the most abundant genera at the sanitary landfill, waste incinerator, and rice field sites, respectively. An antibiotic resistant test for the above bacteria (Micrococcus sp., Microbacterium sp., and Staphylococcus sp.) showed that the Staphylococcus sp. had the strongest resistance to both antibiotics (25.0% resistance for 32 microg ml(-1) of Chloramphenicol and 62.5% resistance for 4 microg ml(-1) of Gentamicin). PMID:20623053

  20. APSAS; an Automated Particle Size Analysis System

    Science.gov (United States)

    Poppe, Lawrence J.; Eliason, A.H.; Fredericks, J.J.

    1985-01-01

    The Automated Particle Size Analysis System integrates a settling tube and an electroresistance multichannel particle-size analyzer (Coulter Counter) with a Pro-Comp/gg microcomputer and a Hewlett Packard 2100 MX(HP 2100 MX) minicomputer. This system and its associated software digitize the raw sediment grain-size data, combine the coarse- and fine-fraction data into complete grain-size distributions, perform method of moments and inclusive graphics statistics, verbally classify the sediment, generate histogram and cumulative frequency plots, and transfer the results into a data-retrieval system. This system saves time and labor and affords greater reliability, resolution, and reproducibility than conventional methods do.

  1. Application examples of APC-03-2 and APC-03-2A airborne particle counters under various contamination conditions

    International Nuclear Information System (INIS)

    Several application examples of the airborne particle counters APC-03-2 and APC-03-2A for monitoring particle size distribution and concentration in air and other gases are described. The computer controlled fast data evaluation and storage provide efficient presentation of the measured data in a variety of table- and histogram-forms, presenting of alarm levels for each size range, observation of alarm history, etc. The device can be applied not only for clean room monitoring and laminar box testing, but also for measuring contamination in health care facilities in workshops using hazardous airborne compounds (e.g. in pharmacology), and in toxicology where the concentration of the contamination may be very high. (author)

  2. Regional monitoring of metals in the Munich metropolitan area: Comparison of biomonitoring (standardized grass culture) with deposition and airborne particles

    International Nuclear Information System (INIS)

    In the Munich metropolitan area a close association of lead (Pb) and antimony (Sb) impacts with traffic was observed in 1992 and 1993. The intercorrelation of both metals was found by samples of standardised grass cultures and was reflected by deposition sampling, too. With respect to location-specific variations, however, both methods revealed differing gradients of Pb and Sb concentrations with increasing distance from traffic. It appeared that Sb variations according to traffic implications were particularly well indicated by means of biomonitoring, while Pb variations were not indicated adequately. As a result, a special qualification of grass to selectively collect metals on airborne dust according to particle sizes was suggested. Further investigations on the correlations between metal biomonitoring, metal deposition and airborne metals in 1994 - 1996 corroborated method-specific sampling features. They in turn showed that one interference is the individual prevalence of the metals on different particle sizes. (author)

  3. Determination of thorium and uranium particles in monazite airborne

    International Nuclear Information System (INIS)

    The work is the determination of the Mass Median Aerodynamic Diameter of Airborne particles of Th and U, produced during the milling of monazite in Monozite Sand Plants. The air samples was collected using a Cascade Impactor from Delron DCI-6 with a flux of 12,5 1/min and cut-off diametes of 0,5, 1,0, 4,0, 8,0 and 16,0 μm. Each stage of the cascate impactor was analysed by measuring the X rays induced in collision with 2 MeV protons acellereted by a 4 MV Van de Graaff acceletor located at University Catolic, PUC, RJ. The MMAD found for Th and U was of 1,15 μm with a geometric standard desviation of 2,0. Take in acount that there are more thorium than uranium in the brazilian monazite, and the 232Th 238U are thr principal isotopes at the Th and U natural radioative decay series, we considered the mass and the activity distribution as equal. The mean concentration of Th (17,0 Bq/m3) record in the air was 42% above 3/10 of international limit for concentration of oxides of thorium in the air, while the concentration of U remaind below 1/10 of the limit for concentration of U3O8 in the air. (author)

  4. PARAMETERS AFFECTING PARTICLE SIZE OF POLYBUTYLACRYLATE MICROGELS

    Institute of Scientific and Technical Information of China (English)

    WANG Xia; YU Yunzhao

    1989-01-01

    The factors affecting particle size of reactive microgels formed during the self-emulsifying copolymerization of unsaturated polyester (UP )with butyl acrylate (BA)have been studied. The parameters discussed are: the proportion of the UP in the monomer mixture, the molecular weight and the carboxyl value of the UP, the phase ratio, the electrolyte concentration and the polar solvent additive. The seeding emulsion polymerization is discussed as well. It turned out that the particle size of the reactive microgels can be controlled in a definite range by changing the experimental conditions. However the particle size distribution becomes broader as the average diameter increases. It is suggested that the agglomeration of primary particles plays an important role during the growth of microgel particle.

  5. ISO INTERNATIONAL STANDARDS FOR PARTICLE SIZING

    Institute of Scientific and Technical Information of China (English)

    Renliang Xu

    2004-01-01

    This introductory article describes how typically an ISO International Standard is made and the activity of the technical committee (TC 24/SC 4) responsible to establish International Standards related to particle sizing methods.

  6. Study of airborne particle generated by free falling powder

    International Nuclear Information System (INIS)

    This study comes within the general framework of industrial facilities' safety research. Indeed, industrial processes, notably in the nuclear field, handle hazardous materials in powder form and can produce large quantities of fugitive dust. The study of the particles resuspension from powders is of interest of first order in order to estimate the consequences of this source term of contamination on the operator, the neighbouring installations and, if necessary, the environment. Up to now, there are very few reliable data in the scientific literature on the particulate emission in case of a scenario with an accidental free fall spill of powder. The powder dustiness evaluation is carried out using coefficients obtained in experiments, or using empirical correlations. The objective of the present work is to study the influence of some parameters involved in the airborne particles production by a free fall of powder. For that purpose, experiments are carried out in order to study the influence of parameters such as the type of discharge, the powder nature, the type of surface on which occurs the powder impaction, the system diameter used for discharge, and the falling mass. The results of mass fractions and number concentrations obtained highlighted the dominating parameters according to the type of discharge employed. Thereafter, the comparisons between our results and the empirical correlations available in the literature showed that those led to an undervaluation of the powder dustiness. This thus led us to develop, starting from the whole of experimental data, empirical correlations taking into account the various parameters studied as well as the interactions. (author)

  7. Hazards of explosives dusts: Particle size effects

    Energy Technology Data Exchange (ETDEWEB)

    Cashdollar, K L; Hertzberg, M; Green, G M

    1992-02-01

    At the request of the Department of Energy, the Bureau of Mines has investigated the hazards of military explosives dispersed as dust clouds in a 20-L test chamber. In this report, the effect of particle size for HMX, HNS, RDX, TATB, and TNT explosives dusts is studied in detail. The explosibility data for these dusts are also compared to those for pure fuel dusts. The data show that all of the sizes of the explosives dusts that were studied were capable of sustaining explosions as dust clouds dispersed in air. The finest sizes (<10 [mu]m) of explosives dusts were less reactive than the intermediate sizes (20 to 60 [mu]m); this is opposite to the particle size effect observed previously for the pure fuel dusts. At the largest sizes studied, the explosives dusts become somewhat less reactive as dispersed dust clouds. The six sizes of the HMX dust were also studied as dust clouds dispersed in nitrogen.

  8. Particle Size Estimation Based on Edge Density

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-xing

    2005-01-01

    Given image sequences of closely packed particles, the underlying aim is to estimate diameters without explicit segmentation. In a way, this is similar to the task of counting objects without directly counting them. Such calculations may, for example, be useful fast estimation of particle size in different application areas. The topic is that of estimating average size (=average diameter) of packed particles, from formulas involving edge density, and the edges from moment-based thresholding are used. An average shape factor is involved in the calculations, obtained for some frames from crude partial segmentation. Measurement results from about 80 frames have been analyzed.

  9. Patterns of covariance between airborne laser scanning metrics and Lorenz curve descriptors of tree size inequality

    NARCIS (Netherlands)

    Valbuena, R.; Maltamo, M.; Martín-Fernández, S.; Packalén, P.; Pascual, C.; Nabuurs, G.J.

    2013-01-01

    The Lorenz curve, as a descriptor of tree size inequality within a stand, has been suggested as a reliable means for characterizing forest structure and distinguishing even from uneven-sized areas. The aim of this study was to achieve a thorough understanding on the relations between airborne laser

  10. Differences in airborne particle and gaseous concentrations in urban air between weekdays and weekends

    International Nuclear Information System (INIS)

    Airborne particle number concentrations and size distributions as well as CO and NOx concentrations monitored at a site within the central business district of Brisbane, Australia were correlated with the traffic flow rate on a nearby freeway with the aim of investigating differences between weekday and weekend pollutant characteristics. Observations over a 5-year monitoring period showed that the mean number particle concentration on weekdays was (8.8±0.1)x103 cm-3 and on weekends (5.9±0.2)x103 cm-3 - a difference of 47%. The corresponding mean particle number median diameters during weekdays and weekends were 44.2±0.3 and 50.2±0.2 nm, respectively. The differences in mean particle number concentration and size between weekdays and weekends were found to be statistically significant at confidence levels of over 99%. During a 1-year period of observation, the mean traffic flow rate on the freeway was 14.2x104 and 9.6x104 vehicles per weekday and weekend day, respectively - a difference of 48%. The mean diurnal variations of the particle number and the gaseous concentrations closely followed the traffic flow rate on both weekdays and weekends (correlation coefficient of 0.86 for particles). The overall conclusion, as to the effect of traffic on concentration levels of pollutant concentration in the vicinity of a major road (about 100 m) carrying traffic of the order of 105 vehicles per day, is that about a 50% increase in traffic flow rate results in similar increases of CO and NOx concentrations and a higher increase of about 70% in particle number concentration. (author)

  11. Intercomparison of 15 aerodynamic particle size spectrometers (APS 3321: uncertainties in particle sizing and number size distribution

    Directory of Open Access Journals (Sweden)

    S. Pfeifer

    2015-11-01

    Full Text Available Aerodynamic particle size spectrometers are a well-established method to measure number size distributions of coarse mode particles in the atmosphere. Quality assurance is essential for atmospheric observational aerosol networks to obtain comparable results with known uncertainties. In a laboratory study within the framework of ACTRIS (Aerosols, Clouds, and Trace gases Research Infrastructure Network, 15 aerodynamic particle size spectrometers (APS model 3321, TSI Inc., St. Paul, MN, USA were compared with a focus on flow rates accuracy, particle sizing, and unit-to-unit variability of the particle number size distribution. Flow rate deviations were relatively small (within a few percent, while the sizing accuracy was found to be within 10 % compared to polystyrene latex (PSL reference particles. The unit-to-unit variability in terms of the particle number size distribution during this study was within 10–20 % for particles in the range of 0.9 up to 3 μm, which is acceptable for atmospheric measurements. For particles smaller than that, the variability increased up to 60 %, probably caused by differences in the counting efficiencies of individual units. Number size distribution data for particles smaller than 0.9 μm in aerodynamic diameter should be only used with caution. For particles larger than 3 μm, the unit-to-unit variability increased as well. A possible reason is an insufficient sizing accuracy in combination with a steeply sloping particle number size distribution and the increasing uncertainty due to decreasing counting. This uncertainty of the particle number size distribution has especially to be considered if higher moments of the size distribution such as the particle volume or mass are calculated, which require the conversion of the aerodynamic diameter measured to a volume equivalent diameter. In order to perform a quantitative quality assurance, a traceable reference method for the particle number concentration in the size

  12. Intercomparison of 15 aerodynamic particle size spectrometers (APS 3321): uncertainties in particle sizing and number size distribution

    Science.gov (United States)

    Pfeifer, Sascha; Müller, Thomas; Weinhold, Kay; Zikova, Nadezda; Martins dos Santos, Sebastiao; Marinoni, Angela; Bischof, Oliver F.; Kykal, Carsten; Ries, Ludwig; Meinhardt, Frank; Aalto, Pasi; Mihalopoulos, Nikolaos; Wiedensohler, Alfred

    2016-04-01

    Aerodynamic particle size spectrometers are a well-established method to measure number size distributions of coarse mode particles in the atmosphere. Quality assurance is essential for atmospheric observational aerosol networks to obtain comparable results with known uncertainties. In a laboratory study within the framework of ACTRIS (Aerosols, Clouds, and Trace gases Research Infrastructure Network), 15 aerodynamic particle size spectrometers (APS model 3321, TSI Inc., St. Paul, MN, USA) were compared with a focus on flow rates, particle sizing, and the unit-to-unit variability of the particle number size distribution. Flow rate deviations were relatively small (within a few percent), while the sizing accuracy was found to be within 10 % compared to polystyrene latex (PSL) reference particles. The unit-to-unit variability in terms of the particle number size distribution during this study was within 10 % to 20 % for particles in the range of 0.9 up to 3 µm, which is acceptable for atmospheric measurements. For particles smaller than that, the variability increased up to 60 %, probably caused by differences in the counting efficiencies of individual units. Number size distribution data for particles smaller than 0.9 µm in aerodynamic diameter should only be used with caution. For particles larger than 3 µm, the unit-to-unit variability increased as well. A possible reason is an insufficient sizing accuracy in combination with a steeply sloping particle number size distribution and the increasing uncertainty due to decreasing counting. Particularly this uncertainty of the particle number size distribution must be considered if higher moments of the size distribution such as the particle volume or mass are calculated, which require the conversion of the aerodynamic diameter measured to a volume equivalent diameter. In order to perform a quantitative quality assurance, a traceable reference method for the particle number concentration in the size range 0.5-3 µm

  13. Self-refreshing characteristics of an airborne particle sensor using a bridged paddle oscillator

    Science.gov (United States)

    Choi, Eunsuk; Lee, Seung-Beck; Park, Bonghyun; Sul, Onejae

    2016-05-01

    We report on the self-refreshing characteristics of a micromachined airborne particle sensor. The sensor consists of a bridge-type beam having an oscillating paddle-type particle collector at its center. When a positive potential is applied to the paddle, the sensor is able to attract and collect negatively charged airborne particles while oscillating close to its resonant frequency and thereby measure their density from the change in the oscillating phase at ˜10 pg resolution. When the applied potential is removed, the collected particles are detached from the sensor due to momentum transfer from the oscillating paddle, thus demonstrating a self-refreshing capability.

  14. Measurement of nonvolatile particle number size distribution

    Science.gov (United States)

    Gkatzelis, G. I.; Papanastasiou, D. K.; Florou, K.; Kaltsonoudis, C.; Louvaris, E.; Pandis, S. N.

    2016-01-01

    An experimental methodology was developed to measure the nonvolatile particle number concentration using a thermodenuder (TD). The TD was coupled with a high-resolution time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle sizer (SMPS) that provided the number size distribution of the aerosol in the range from 10 to 500 nm. The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (> 98 %) of secondary organic as well as freshly nucleated particles, using a TD temperature of 400 °C and a centerline residence time of 15 s. This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of number concentration and size distribution for particles emitted from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80 % of particle number concentration remained after passing through the thermodenuder, suggesting that nearly all biomass burning particles had a nonvolatile core. These remaining particles consisted mostly of black carbon (60 % mass contribution) and organic aerosol (OA; 40 %). Organics that had not evaporated through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) as determined from AMS source apportionment analysis. For periods during which traffic contribution was dominant 50-60 % of the particles had a nonvolatile core while the rest evaporated at 400 °C. The remaining particle mass consisted mostly of black carbon with an 80 % contribution, while OA was responsible for another 15-20 %. Organics were mostly hydrocarbon-like OA (HOA) and OOA. These results suggest that even at 400 °C some fraction of the OA does not evaporate from particles emitted from common combustion processes, such as biomass burning and car engines, indicating that a fraction of this type of OA

  15. Correlation analysis of size-resolved airborne particulate matter with classified meteorological conditions

    Science.gov (United States)

    Nguyen, Minh-Viet; Park, Gee-Hyeong; Lee, Byeong-Kyu

    2016-05-01

    This study analyzed correlations between classified meteorological conditions and size-resolved particulate matter (PM) concentrations over year. Seasonal measurements of airborne PM were conducted on the roof of a university building located in an urban residential area in Ulsan, Korea. A total of 267 daily PM samples were obtained using a nine-stage cascade impactor during the 12-month sampling period (March 2011-March 2012). Among this period, the average PM1.0, PM2.5, PM2.5-10, and PM10 concentrations were the lowest during the summer. The highest and lowest monthly average PM concentrations for all particle size ranges were observed in dry April and humid July, respectively. The PM1.0, PM2.5, PM2.5-10, and PM10 concentrations were negatively correlated (p 80 %) and under moderate humidity conditions (50-80 %) only during the winter season. PM concentrations also negatively correlated with precipitation (p 30 mm) and moderate (10-30 mm) rainfall conditions and only under light rainfall (speed [strong (>7 m/s) and moderate (3-7 m/s) wind]. Most PM concentrations correlated positively with ambient temperature, however, only on days with an average temperature above 20 °C. High and moderate temperatures negatively correlated with high and moderate humid conditions, while low and extra low temperatures in winter period showed positive correlation with high and moderate humidity.

  16. Sampling and Characterization of Airborne Particle from Car Brakes Testing

    Czech Academy of Sciences Publication Activity Database

    Moravec, Pavel; Smolík, Jiří; Schwarz, Jaroslav; Ševčíková, Irena; Kukutschová, J.; Tomášek, V.

    Praha: Česká aerosolová společnost, 2009, s. 25-30. ISBN 978-80-86186-20-7. [Konference České aerosolové společnosti /10./. Čejkovice (CZ), 12.11.2009-13.11.2009] R&D Projects: GA ČR GA106/07/1436 Institutional research plan: CEZ:AV0Z40720504 Keywords : friction * size resolved sampling * wear particles Subject RIV: CF - Physical ; Theoretical Chemistry http://cas.icpf.cas.cz/download/Sbornik_VKCAS_2009.pdf

  17. A new look at inhalable metalliferous airborne particles on rail subway platforms.

    Science.gov (United States)

    Moreno, Teresa; Martins, Vânia; Querol, Xavier; Jones, Tim; BéruBé, Kelly; Minguillón, Maria Cruz; Amato, Fulvio; Capdevila, Marta; de Miguel, Eladio; Centelles, Sonia; Gibbons, Wes

    2015-02-01

    Most particles breathed on rail subway platforms are highly ferruginous (FePM) and extremely small (nanometric to a few microns in size). High magnification observations of particle texture and chemistry on airborne PM₁₀ samples collected from the Barcelona Metro, combined with published experimental work on particle generation by frictional sliding, allow us to propose a general model to explain the origin of most subway FePM. Particle generation occurs by mechanical wear at the brake-wheel and wheel-rail interfaces, where magnetic metallic flakes and splinters are released and undergo progressive atmospheric oxidation from metallic iron to magnetite and maghemite. Flakes of magnetite typically comprise mottled mosaics of octahedral nanocrystals (10-20 nm) that become pseudomorphed by maghemite. Continued oxidation results in extensive alteration of the magnetic nanostructure to more rounded aggregates of non-magnetic hematite nanocrystals, with magnetic precursors (including iron metal) still preserved in some particle cores. Particles derived from steel wheel and rails contain a characteristic trace element chemistry, typically with Mn/Fe=0.01. Flakes released from brakes are chemically very distinctive, depending on the pad composition, being always carbonaceous, commonly barium-rich, and texturally inhomogeneous, with trace elements present in nanominerals incorporated within the crystalline structure. In the studied subway lines of Barcelona at least there appears to be only a minimal aerosol contribution from high temperature processes such as sparking. To date there is no strong evidence that these chemically and texturally complex inhalable metallic materials are any more or less toxic than street-level urban particles, and as with outdoor air, the priority in subway air quality should be to reduce high mass concentrations of aerosol present in some stations. PMID:25461038

  18. Airborne contamination of forest soils by carbonaceous particles from industrial coal processing

    OpenAIRE

    Schmidt, M. W. I.; Knicker, Heike; Hatcher, Patrick G.; Kögel-Knabner, I.

    2000-01-01

    In the German Ruhr-area industrial coal processing emitted large amounts of carbonaceous particles for a century until 1970. Our objectives were to detect the presence of airborne carbonaceous particles and assess their impact on the chemical structure of soil organic matter in two forest soils (Podzols) with potential sources of carbonaceous particles approximately 10 to 30 km away. Contamination was not visible macroscopicaily. Organic matter was characterized in bulk soils and in particle-...

  19. ELECTROHYDRODYNAMIC ENHANCED TRANSPORT AND TRAPPING OF AIRBORNE PARTICLES TO A MICROFLUIDIC AIR-LIQUID INTERFACE

    OpenAIRE

    Sandström, Niklas; Frisk, Thomas; Stemme, Göran; van der Wijngaart, Wouter

    2008-01-01

    We introduce a novel approach for greatly improved transport and trapping of airborne sample to a microfluidic analysis system by integrating an electrohydrodynamic (EHD) air pump with a microfluidic air-liquid interface. In our system, a negative corona discharge partially ionizes the air around a sharp electrode tip while the electrostatic field accelerates airborne particles towards an electrically grounded liquid surface, where they absorb. The air-liquid interface is fixated at the micro...

  20. Concentrations and Sources of Airborne Particles in a Neonatal Intensive Care Unit

    OpenAIRE

    Licina, Dusan; Bhangar, Seema; Brooks, Brandon; Baker, Robyn; Firek, Brian; Tang, Xiaochen; Morowitz, Michael J; Banfield, Jillian F; Nazaroff, William W.

    2016-01-01

    Premature infants in neonatal intensive care units (NICUs) have underdeveloped immune systems, making them susceptible to adverse health consequences from air pollutant exposure. Little is known about the sources of indoor airborne particles that contribute to the exposure of premature infants in the NICU environment. In this study, we monitored the spatial and temporal variations of airborne particulate matter concentrations along with other indoor environmental parameters and human occupanc...

  1. Concentrations and Sources of Airborne Particles in a Neonatal Intensive Care Unit.

    OpenAIRE

    Licina, D; Bhangar, S; Brooks, B.; Baker, R; Firek, B; Tang, X; Morowitz, MJ; Banfield, JF; Nazaroff, WW

    2016-01-01

    Premature infants in neonatal intensive care units (NICUs) have underdeveloped immune systems, making them susceptible to adverse health consequences from air pollutant exposure. Little is known about the sources of indoor airborne particles that contribute to the exposure of premature infants in the NICU environment. In this study, we monitored the spatial and temporal variations of airborne particulate matter concentrations along with other indoor environmental parameters and human occupanc...

  2. Ventilation conditions and air-borne bacteria and particles in operating theatres: proposed safe economies.

    OpenAIRE

    Clark, R. P.; Reed, P. J.; Seal, D V; Stephenson, M. L.

    1985-01-01

    Concentrations of air-borne bacteria and particles have been measured in turbulently ventilated operating theatres in full flow, half flow and zero flow conditions. Increased air-borne challenge produced by human activity and by mechanical cleaning procedures is demonstrated: die-away of this contamination is shown to be related to the ventilation rate. Ventilation can be reduced or turned off at night and during weekends, and cleaning can also be carried out, without increased risk of infect...

  3. In situ exhaust cloud measurements. [particle size distribution and cloud physics of rocket exhaust clouds

    Science.gov (United States)

    Wornom, D.

    1980-01-01

    Airborne in situ exhaust cloud measurements were conducted to obtain definitions of cloud particle size range, Cl2 content, and HCl partitioning. Particle size distribution data and Cl2 measurements were made during the May, August, and September 1977 Titan launches. The measurements of three basic effluents - HCl, NO sub X, and particles - against minutes after launch are plotted. The maximum observed HCl concentration to the maximum Cl2 concentration are compared and the ratios of the Cl2 to the HCl is calculated.

  4. Estimating average tree crown size using high-resolution airborne data

    Czech Academy of Sciences Publication Activity Database

    Brovkina, Olga; Latypov, I.; Cienciala, E.

    2015-01-01

    Roč. 9, may 13 (2015), 096053-1-096053-13. ISSN 1931-3195 R&D Projects: GA MŠk(CZ) LO1415; GA MŠk OC09001 Institutional support: RVO:67179843 Keywords : crown size * airborne data * spruce * granulometry Subject RIV: EH - Ecology, Behaviour Impact factor: 1.183, year: 2014

  5. Airborne observations of new particle formation events in the boundary layer using a Zeppelin

    Science.gov (United States)

    Lampilahti, Janne; Manninen, Hanna E.; Nieminen, Tuomo; Mirme, Sander; Pullinen, Iida; Yli-Juuti, Taina; Schobesberger, Siegfried; Kangasluoma, Juha; Kontkanen, Jenni; Lehtipalo, Katrianne; Ehn, Mikael; Mentel, Thomas F.; Petäjä, Tuukka; Kulmala, Markku

    2014-05-01

    Atmospheric new particle formation (NPF) is a frequent and ubiquitous process in the atmosphere and a major source of newly formed aerosol particles [1]. However, it is still unclear how the aerosol particle distribution evolves in space and time during an NPF. We investigated where in the planetary boundary layer does NPF begin and how does the aerosol number size distribution develop in space and time during it. We measured in Hyytiälä, southern Finland using ground based and airborne measurements. The measurements were part of the PEGASOS project. NPF was studied on six scientific flights during spring 2013 using a Zeppelin NT class airship. Ground based measurements were simultaneously conducted at SMEAR II station located in Hyytiälä. The flight profiles over Hyytiälä were flown between sunrise and noon during the growth of the boundary layer. The profiles over Hyytiälä covered vertically a distance of 100-1000 meters reaching the mixed layer, stable (nocturnal) boundary layer and the residual layer. Horizontally the profiles covered approximately a circular area of four kilometers in diameter. The measurements include particle number size distribution by Neutral cluster and Air Ion Spectrometer (NAIS), Differential Mobility Particle Sizer (DMPS) and Particle Size Magnifier (PSM) [2], meteorological parameters and position (latitude, longitude and altitude) of the Zeppelin. Beginning of NPF was determined from an increase in 1.7-3 nm ion concentration. Height of the mixed layer was estimated from relative humidity measured on-board the Zeppelin. Particle growth rate during NPF was calculated. Spatial inhomogeneities in particle number size distribution during NPF were located and the birthplace of the particles was estimated using the growth rate and trajectories. We observed a regional NPF event that began simultaneously and evolved uniformly inside the mixed layer. In the horizontal direction we observed a long and narrow high concentration plume of

  6. Photographic techniques for characterizing streambed particle sizes

    Science.gov (United States)

    Whitman, M.S.; Moran, E.H.; Ourso, R.T.

    2003-01-01

    We developed photographic techniques to characterize coarse (>2-mm) and fine (???2-mm) streambed particle sizes in 12 streams in Anchorage, Alaska. Results were compared with current sampling techniques to assess which provided greater sampling efficiency and accuracy. The streams sampled were wade-able and contained gravel - cobble streambeds. Gradients ranged from about 5% at the upstream sites to about 0.25% at the downstream sites. Mean particle sizes and size-frequency distributions resulting from digitized photographs differed significantly from those resulting from Wolman pebble counts for five sites in the analysis. Wolman counts were biased toward selecting larger particles. Photographic analysis also yielded a greater number of measured particles (mean = 989) than did the Wolman counts (mean = 328). Stream embeddedness ratings assigned from field and photographic observations were significantly different at 5 of the 12 sites, although both types of ratings showed a positive relationship with digitized surface fines. Visual estimates of embeddedness and digitized surface fines may both be useful indicators of benthic conditions, but digitizing surface fines produces quantitative rather than qualitative data. Benefits of the photographic techniques include reduced field time, minimal streambed disturbance, convenience of postfield processing, easy sample archiving, and improved accuracy and replication potential.

  7. Measurement of the electrostatic charge in airborne particles: II - particle charge distribution of different aerosols

    Directory of Open Access Journals (Sweden)

    M. V. Rodrigues

    2006-03-01

    Full Text Available This work gives sequence to the study on the measurement of the electrostatic charges in aerosols. The particle charge classifier developed for this purpose and presented in the previous paper (Marra and Coury, 2000 has been used here to measure the particle charge distribution of a number of different aerosols. The charges acquired by the particles were naturally derived from the aerosol generation procedure itself. Two types of aerosol generators were used: the vibrating orifice generator and turntable Venturi plate generator. In the vibrating orifice generator, mono-dispersed particles were generated by a solution of water/ethanol/methylene blue, while in the rotating plate generator, six different materials were utilized. The results showed no clear dependence between electric charge and particle diameter for the mono-dispersed aerosol. However, for the poly-dispersed aerosols, a linear dependence between particle size and charge could be noticed.

  8. Langevin granulometry of the particle size distribution

    Science.gov (United States)

    Kákay, Attila; Gutowski, M. W.; Takacs, L.; Franco, V.; Varga, L. K.

    2004-06-01

    The problem of deriving the particle size distribution directly from superparamagnetic magnetization curves is studied by three mathematical methods: (1) least-squares deviation with regularization procedure, (2) simulated annealing and (3) genetic algorithm. Software has been developed for the latest versions of all these methods and its performance compared for various models of underlying particle size distributions (Dirac dgr-like, lognormal- and Gaussian-shaped). For single peak distributions all three methods give reasonable and similar results, but for bimodal distributions the genetic algorithm is the only acceptable one. The genetic algorithm is able to recover with the same precision both the lognormal and Gaussian single and double (mixed) model distributions. The sensitivity of the genetic algorithm—the most promising method—to uncertainty of measurements was also tested; correct peak position and its half width were recovered for Gaussian distributions, when the analysed data were contaminated with noise of up to 5% of MS.

  9. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry.

    Science.gov (United States)

    Kero, Ida Teresia; Jørgensen, Rikke Bramming

    2016-01-01

    The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPI(TM)), a Fast Mobility Particle Sizer (FMPS(TM)), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification. PMID:27598180

  10. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry

    Directory of Open Access Journals (Sweden)

    Ida Teresia Kero

    2016-09-01

    Full Text Available The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPITM, a Fast Mobility Particle Sizer (FMPSTM, and a Condensation Particle Counter (CPC. The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification.

  11. Characterization of trace metals in airborne carbonaceous aerosols by single-particle EDX – Scanning Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Pietrodangelo A.

    2013-04-01

    Full Text Available The presence of fine and ultrafine metal particles has been evidenced in size segregated airborne carbonaceous aerosols collected at one industrial and two background (urban and rural sites during an extended field campaign in Central Italy. Analysis of the backscattered electrons (BSE by SEM – EDX demonstrated an effective potential in evidencing main structural features of the metal content in identified carbon aerosols. Many observed ultrafine metal particles appear embedded in the skeleton of carbonaceous individual particles and aggregates in the coarse fraction, while the same is not evident in the case of mixed carbon-sulphates aerosol that has been detected in the submicron size. These carbon-sulphates formations include indeed nano-sized metal particles that appear physically combined but not embedded. Also, larger metal particles (ranging around 1 μm physical size were observed close to carbon materials, but not included in their structure. Main compositional differences of metal particles with size segregation could be evidenced by energy – dispersive X ray spectrometry (EDX. Larger particles are mainly rich in Fe, frequently in presence of Mn, Cu, Cr and Zn in variable proportions; either oxidized or elemental metals were detected. On the other hand, ultrafine particles associated with carbon–sulphates aerosol are enriched in Pb and Zn, although the presence of other trace elements not detectable by SEM – EDX technique cannot be excluded. Moreover, Ce-enriched ultrafine particles were clearly determined in cenospheres. Conversely, inclusion of fine and ultrafine metal particles was rarely or not observed in soot aggregates.

  12. Chaotic mixing of finite-sized particles

    Science.gov (United States)

    Omurtag, Ahmet Can

    1997-10-01

    Dynamical systems concepts have been used to analyze the behavior of rigid spherical finite-sized particles in chaotic flows in the eccentric annular system. If the particles are sufficiently small they follow the fluid streamlines. Then the dynamical system is Hamiltonian as a result of the presence of a streamfunction for the two- dimensional incompressible flow. The Stokes number characterizes the significance of particle inertia. It is shown that the bifurcations of the dynamical system can be harnessed for separating particles with different physical properties. These results are numerically obtained for finite-sized particles in Stokes flows. Departure from Stokes flow toward higher Reynolds numbers results in longer transients in the fluid velocity field. It also changes the steady state pattern of the streamlines. Mixing under chaotic stirring procedures with up to Re=100 indicates a general tendency toward poorer mixing per cycle. Results obtained by the numerically generated fluid velocity field demonstrated good agreement with experimental results. The extent and shape of the chaotic regions are not, in general, radically modified as the Reynolds number increases. It was shown that the unstable manifolds of the underlying mapping based on Stokes flow provides a template for deformations in the flow even beyond the Stokes regime as well as with particle inertia and q/not=1. It was also shown that the stable and unstable manifolds can be located by calculating the finite-time Lyapunov exponents of a very large number of trajectories in the domain. Mixing in the eccentric annulus is applied to the problem of collecting fetal cells from maternal circulation of blood. Fetal cells were modeled as small spherical particles suspended in a Newtonian fluid filling the gap in a small eccentric annular mixing device. Two separate model collecting devices are used. The first model utilizes vertically placed and antibody coated fibers that adhere to fetal cells on

  13. Chamber bioaerosol study: human emissions of size-resolved fluorescent biological aerosol particles

    OpenAIRE

    Bhangar, Seema; Adams, Rachel I.; Pasut, Wilmer; Huffman, Alex; Arens, Edward A.; Taylor, John W; Bruns, Tom D; Nazaroff, William W

    2015-01-01

    Humans are a prominent source of airborne biological particles in occupied indoor spaces, but few studies have quantified human bioaerosol emissions. The chamber investigation reported here employs a fluorescence-based technique to evaluate bioaerosols with high temporal and particle size resolution. In a 75-m3 chamber, occupant emission rates of coarse (2.5–10 μm) fluorescent biological aerosol particles (FBAPs) under seated, simulated office-work conditions averaged 0.9 ± 0.3 million partic...

  14. Measurements of size and composition of particles in polar stratospheric clouds from infrared solar absorption spectra

    Science.gov (United States)

    Kinne, S.; Toon, O. B.; Toon, G. C.; Farmer, C. B.; Browell, E. V.; Mccormick, M. P.

    1989-01-01

    Results are presented on polar stratospheric cloud (PSC) observations, based on IR measurements of solar extinction, made by the airborne JPL Mark IV interferometer during the Airborne Antarctic Ozone Expedition in 1987, together with the instrumentation and the theoretical aspects of data analysis. Thirty-three PSC cases were analyzed and categorized into two types, I and II, which were found to occur at different altitudes during September. Type I clouds, seen at altitudes above 15 km, contained particles with radii of about 0.5 micarons and nitric acid concentrations greater than 40 percent, while type II clouds, found usually below 15 km, contained particles with radii of 6 microns and larger, composed of water ice. In addition, particles of larger than the 15-micron-size detection limit were encounterd.

  15. DUAL-CHANNEL PARTICLE SIZE AND SHAPE ANALYZER

    Institute of Scientific and Technical Information of China (English)

    Arjen van der Schoot

    2004-01-01

    @@ Fig. 1 shows a newly developed analyzer (Ankersmid CIS-100) that brings together two different measurement channels for accurate size and shape measurement of spherical and non-spherical particles. The size of spherical particles is measured by a HeNe Laser Beam; the size of non-spherical particles is analyzed by Dynamic Video Analysis of the particles' shape.

  16. PHIPS-HALO: the airborne Particle Habit Imaging and Polar Scattering probe - Part 1: Design and operation

    Science.gov (United States)

    Abdelmonem, Ahmed; Järvinen, Emma; Duft, Denis; Hirst, Edwin; Vogt, Steffen; Leisner, Thomas; Schnaiter, Martin

    2016-07-01

    The number and shape of ice crystals present in mixed-phase and ice clouds influence the radiation properties, precipitation occurrence and lifetime of these clouds. Since clouds play a major role in the climate system, influencing the energy budget by scattering sunlight and absorbing heat radiation from the earth, it is necessary to investigate the optical and microphysical properties of cloud particles particularly in situ. The relationship between the microphysics and the single scattering properties of cloud particles is usually obtained by modelling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. There is a demand to obtain both information correspondently and simultaneously for individual cloud particles in their natural environment. For evaluating the average scattering phase function as a function of ice particle habit and crystal complexity, in situ measurements are required. To this end we have developed a novel airborne optical sensor (PHIPS-HALO) to measure the optical properties and the corresponding microphysical parameters of individual cloud particles simultaneously. PHIPS-HALO has been tested in the AIDA cloud simulation chamber and deployed in mountain stations as well as research aircraft (HALO and Polar 6). It is a successive version of the laboratory prototype instrument PHIPS-AIDA. In this paper we present the detailed design of PHIPS-HALO, including the detection mechanism, optical design, mechanical construction and aerodynamic characterization.

  17. Particle size influence on effective permittivity of particle-gas mixture with particle clusters

    Institute of Scientific and Technical Information of China (English)

    Lijun Xu; Chang Liu; Zhang Cao; Xiaomin Li

    2013-01-01

    The influence of particle size on the effective permittivity of a particle-gas mixture in the presence of particle clusters was studied using numerical analysis involving the three-dimensional finite element method.The effective permittivity of the mixture was obtained by calculating the electrostatic energy generated in the computation domain.Numerical results show that for fixed volume fraction of particles in the mixture,the effective permittivity of the mixture increases with decreasing particle size.Static experiments were carried out by using a differential capacitance sensor with parallel plates.The variation of the effective permittivity with particle size is shown by experimental data to agree with the numerical results.The methodology described and the results obtained in this paper may be used to help modify the measurement of particles volume fraction in the presence of particle clusters when a capacitance sensor is used.

  18. Vertical Variation of Ice Particle Size in Convective Cloud Tops

    Science.gov (United States)

    Van Diedenhoven, Bastiaan; Fridlind, Ann M.; Cairns, Brian; Ackerman, Andrew S.; Yorks, John E.

    2016-01-01

    A novel technique is used to estimate derivatives of ice effective radius with respect to height near convective cloud tops (dr(sub e)/dz) from airborne shortwave reflectance measurements and lidar. Values of dr(sub e)/dz are about -6 micrometer/km for cloud tops below the homogeneous freezing level, increasing to near 0 micrometer/km above the estimated level of neutral buoyancy. Retrieved dr(sub e)/dz compares well with previously documented remote sensing and in situ estimates. Effective radii decrease with increasing cloud top height, while cloud top extinction increases. This is consistent with weaker size sorting in high, dense cloud tops above the level of neutral buoyancy where fewer large particles are present and with stronger size sorting in lower cloud tops that are less dense. The results also confirm that cloud top trends of effective radius can generally be used as surrogates for trends with height within convective cloud tops. These results provide valuable observational targets for model evaluation.

  19. Calibration of the passive cavity aerosol spectrometer probe for airborne determination of the size distribution

    Directory of Open Access Journals (Sweden)

    Y. Cai

    2013-09-01

    Full Text Available This work describes calibration methods for the particle sizing and particle concentration systems of the passive cavity aerosol spectrometer probe (PCASP. Laboratory calibrations conducted over six years, in support of the deployment of a PCASP on a cloud physics research aircraft, are analyzed. Instead of using the many calibration sizes recommended by the PCASP manufacturer, a relationship between particle diameter and scattered light intensity is established using three sizes of mobility-selected polystyrene latex particles, one for each amplifier gain stage. In addition, studies of two factors influencing the PCASP's determination of the particle size distribution – amplifier baseline and particle shape – are conducted. It is shown that the PCASP-derived size distribution is sensitive to adjustments of the sizing system's baseline voltage, and that for aggregates of spheres, a PCASP-derived particle size and a sphere-equivalent particle size agree within uncertainty dictated by the PCASP's sizing resolution. Robust determinations of aerosol concentration, and size distribution, also require calibration of the PCASP's aerosol flowrate sensor. Sensor calibrations, calibration drift, and the sensor's non-linear response are documented.

  20. Calibration of the passive cavity aerosol spectrometer probe for airborne determination of the size distribution

    Directory of Open Access Journals (Sweden)

    Y. Cai

    2013-05-01

    Full Text Available This work describes calibration methods for the particle sizing and particle concentration systems of the passive cavity aerosol spectrometer probe (PCASP. Laboratory calibrations conducted over six years, in support of the deployment of a PCASP on a cloud physics research aircraft, are analyzed. Instead of using the many calibration sizes recommended by the PCASP manufacturer, a relationship between particle diameter and scattered light intensity is established using three sizes of mobility-selected polystyrene latex particles, one for each amplifier gain stage. In addition, studies of two factors influencing the PCASP's determination of the particle size distribution – amplifier baseline and particle shape – are conducted. It is shown that the PCASP-derived size distribution is sensitive to adjustments of the sizing system's baseline voltage, and that for aggregate spheres, a PCASP-derived particle size and a sphere-equivalent particle size agree within uncertainty dictated by the PCASP's sizing resolution. Robust determination of aerosol concentration, and size distribution, also require calibration of the PCASP's aerosol flowrate sensor. Sensor calibrations, calibration drift, and the sensor's non-linear response are documented.

  1. Particle size of spray-dried soymilk

    International Nuclear Information System (INIS)

    Soymilk was spray-dried under various combinations of inlet-heated air temperature (255, 265, and 275 degrees C), atomizer speed (19,300 and 26,800 rpm), and feed rate (0.37 and 0.58 L/m) and sieved using ultrasonic and shaker/tapping methods to determine mean particle size diameter. High fat content of the soymilk required the addition of dispersion agents to increase flowability. Nine algorithms were used to calculate mean diameter from experimental data. These values were compared with Sauter and volume mean diameter estimates obtained from six empirical relations reported in the literature for spray dried products. Estimates from experimental data were found to depend on the processing temperature, sieving method and dispersion agent used, and did not agree with literature reporting decreases in particle size with increases in atomizer speed. Good estimates of Sauter and volume mean diameters were obtained from the Friedman's correlation and the modified Herring and Marshall correlation, respectively

  2. Determining size-specific emission factors for environmental tobacco smoke particles

    Energy Technology Data Exchange (ETDEWEB)

    Klepeis, Neil E.; Apte, Michael G.; Gundel, Lara A.; Sextro, Richard G.; Nazaroff, William W.

    2002-07-07

    Because size is a major controlling factor for indoor airborne particle behavior, human particle exposure assessments will benefit from improved knowledge of size-specific particle emissions. We report a method of inferring size-specific mass emission factors for indoor sources that makes use of an indoor aerosol dynamics model, measured particle concentration time series data, and an optimization routine. This approach provides--in addition to estimates of the emissions size distribution and integrated emission factors--estimates of deposition rate, an enhanced understanding of particle dynamics, and information about model performance. We applied the method to size-specific environmental tobacco smoke (ETS) particle concentrations measured every minute with an 8-channel optical particle counter (PMS-LASAIR; 0.1-2+ micrometer diameters) and every 10 or 30 min with a 34-channel differential mobility particle sizer (TSI-DMPS; 0.01-1+ micrometer diameters) after a single cigarette or cigar was machine-smoked inside a low air-exchange-rate 20 m{sup 3} chamber. The aerosol dynamics model provided good fits to observed concentrations when using optimized values of mass emission rate and deposition rate for each particle size range as input. Small discrepancies observed in the first 1-2 hours after smoking are likely due to the effect of particle evaporation, a process neglected by the model. Size-specific ETS particle emission factors were fit with log-normal distributions, yielding an average mass median diameter of 0.2 micrometers and an average geometric standard deviation of 2.3 with no systematic differences between cigars and cigarettes. The equivalent total particle emission rate, obtained integrating each size distribution, was 0.2-0.7 mg/min for cigars and 0.7-0.9 mg/min for cigarettes.

  3. Airborne measurements over the boreal forest of southern Finland during new particle formation events in 2009 and 2010

    Energy Technology Data Exchange (ETDEWEB)

    Schobesberger, S.; Vaananen, R.; Leino, K. [Helsinki Univ. (Finland). Dept. of Physics, Division of Atmospheric Sciences] [and others

    2013-06-01

    We conducted airborne observations of aerosol physical properties over the southern Finland boreal forest environment. The aim was to investigate the lower tropospheric aerosol (up to 4-km altitude) over an area of 250 by 200 km, in particular during new particle formation (NPF) events, and to address the spatial variability of aerosol number concentration and number size distribution. The regional NPF events, detected both airborne and at the ground, with air masses originating from the Arctic or northern Atlantic Ocean were studied throughout the boundary layer and throughout the area covered. Three suitable case studies are presented in more detail. In two of these studies, the concentrations of nucleation mode particles (3-10 nm in diameter) were found considerably higher (up to a factor of 30) in the upper parts of the planetary boundary layer compared to ground-based measurements during the nucleation events. The observed vertical variation can be connected to boundary layer dynamics and interactions between the boundary layer and the lower free troposphere, likely yielding high concentrations of newly formed aerosol particles. Our results suggest that nucleation does not necessarily occur close to the surface. In one presented case we found evidence of NPF occurring in a limited area above cloud, in the complete absence of a regional NPF event. (orig.)

  4. Production of sized particles of uranium oxides and uranium oxyfluorides

    International Nuclear Information System (INIS)

    A process for converting uranium hexafluoride to uranium dioxide of a relatively large particle size in a fluidized bed reactor by mixing uranium hexafluoride with a mixture of steam and hydrogen to form a mixture of uranium oxide and uranium oxyfluoride seed particles of varying sizes, separating the larger particles from the smaller particles in a cyclone separator, recycling the smaller seed particles through the ejector to increase their size, and introducing the larger seed particles from the cyclone separator into a fluidized bed reactor where the seed particles serve as nuclei on which coarser particles of uranium dioxide are formed. (Patent Office Record)

  5. Retention of airborne particles in granular bed filters

    International Nuclear Information System (INIS)

    A literature survey was made on theoretical models for the prediction of particle retention in sand beds. Also data on observed retention was collected from the literature. Based on this information, a semi-empirical model was compiled. Comparison of the model with published retention data shows a general agreement. (Auth.)

  6. Evaluation of cell sorting aerosols and containment by an optical airborne particle counter.

    Science.gov (United States)

    Xie, Mike; Waring, Michael T

    2015-08-01

    Understanding aerosols produced by cell sorting is critical to biosafety risk assessment and validation of containment efficiency. In this study an Optical Airborne Particle Counter was used to analyze aerosols produced by the BD FACSAria and to assess the effectiveness of its aerosol containment. The suitability of using this device to validate containment was directly compared to the Glo-Germ method put forth by the International Society for Advancement of Cytometry (ISAC) as a standard for testing. It was found that high concentrations of aerosols ranging from 0.3 µm to 10 µm can be detected in failure mode, with most less than 5 µm. In most cases, while numerous aerosols smaller than 5 µm were detected by the Optical Airborne Particle Counter, no Glo-Germ particles were detected, indicating that small aerosols are under-evaluated by the Glo-Germ method. The results demonstrate that the Optical Airborne Particle Counter offers a rapid, economic, and quantitative analysis of cell sorter aerosols and represents an improved method over Glo-Germ for the task of routine validation and monitoring of aerosol containment for cell sorting. PMID:26012776

  7. Automated classification of single airborne particles from two-dimensional angle-resolved optical scattering (TAOS) patterns by non-linear filtering

    Science.gov (United States)

    Crosta, Giovanni Franco; Pan, Yong-Le; Aptowicz, Kevin B.; Casati, Caterina; Pinnick, Ronald G.; Chang, Richard K.; Videen, Gorden W.

    2013-12-01

    Measurement of two-dimensional angle-resolved optical scattering (TAOS) patterns is an attractive technique for detecting and characterizing micron-sized airborne particles. In general, the interpretation of these patterns and the retrieval of the particle refractive index, shape or size alone, are difficult problems. By reformulating the problem in statistical learning terms, a solution is proposed herewith: rather than identifying airborne particles from their scattering patterns, TAOS patterns themselves are classified through a learning machine, where feature extraction interacts with multivariate statistical analysis. Feature extraction relies on spectrum enhancement, which includes the discrete cosine FOURIER transform and non-linear operations. Multivariate statistical analysis includes computation of the principal components and supervised training, based on the maximization of a suitable figure of merit. All algorithms have been combined together to analyze TAOS patterns, organize feature vectors, design classification experiments, carry out supervised training, assign unknown patterns to classes, and fuse information from different training and recognition experiments. The algorithms have been tested on a data set with more than 3000 TAOS patterns. The parameters that control the algorithms at different stages have been allowed to vary within suitable bounds and are optimized to some extent. Classification has been targeted at discriminating aerosolized Bacillus subtilis particles, a simulant of anthrax, from atmospheric aerosol particles and interfering particles, like diesel soot. By assuming that all training and recognition patterns come from the respective reference materials only, the most satisfactory classification result corresponds to 20% false negatives from B. subtilis particles and <11% false positives from all other aerosol particles. The most effective operations have consisted of thresholding TAOS patterns in order to reject defective ones

  8. Allergens in Paved Road Dust and Airborne Particles

    OpenAIRE

    Miguel, Ann G.; Cass, Glen R.; Glovsky, M. Michael; Weiss, Jay

    1999-01-01

    Paved road dust present on the surface of streets in Southern California consists of a complex mixture of soil dust, deposited motor vehicle exhaust particles, tire dust, brake lining wear dust, plant fragments, and other biological materials. The research presented here shows that allergens from at least 20 different source materials are found in the paved road dust. These include pollens and pollen fragments, animal dander, and molds. When paved road dust is resuspended into the atmosphere ...

  9. Characterization of individual airborne particles in Taiyuan City, China

    OpenAIRE

    Xie, R. K.; Seip, H. M.; L. Liu; Zhang, D.S.

    2009-01-01

    Taiyuan, the capital of Shanxi province, China, is one of the most polluted cities in the world. To characterize the ambient particulate pollution, samples of particulates with aerodynamic diameter less than 10 µm (PM10) were collected during a 6-day campaign. Individual particles were analyzed by Scanning Electron Microscope with Energy-Dispersive Spectrometer (SEM-EDS) to determine their chemical composition. Meanwhile, photomicrographs were obtained from SEM to aid in particles’ source ide...

  10. Identification and characterization of individual airborne volcanic ash particles by Raman microspectroscopy.

    Science.gov (United States)

    Ivleva, Natalia P; Huckele, Susanne; Weinzierl, Bernadett; Niessner, Reinhard; Haisch, Christoph; Baumann, Thomas

    2013-11-01

    We present for the first time the Raman microspectroscopic identification and characterization of individual airborne volcanic ash (VA) particles. The particles were collected in April/May 2010 during research aircraft flights, which were performed by Deutsches Zentrum für Luft- und Raumfahrt in the airspace near the Eyjafjallajökull volcano eruption and over Europe (between Iceland and Southern Germany). In addition, aerosol particles were sampled by an Electrical Low Pressure Impactor in Munich, Germany. As references for the Raman analysis, we used the spectra of VA collected at the ground near the place of eruption, of mineral basaltic rock, and of different minerals from a database. We found significant differences in the spectra of VA and other aerosol particles (e.g., soot, nitrates, sulfates, and clay minerals), which allowed us to identify VA among other atmospheric particulate matter. Furthermore, while the airborne VA shows a characteristic Raman pattern (with broad band from ca. 200 to ca. 700 cm(-1) typical for SiO₂ glasses and additional bands of ferric minerals), the differences between the spectra of aged and fresh particles were observed, suggesting differences in their chemical composition and/or structure. We also analyzed similarities between Eyjafjallajökull VA particles collected at different sampling sites and compared the particles with a large variety of glassy and crystalline minerals. This was done by applying cluster analysis, in order to get information on the composition and structure of volcanic ash. PMID:24121468

  11. Indoor and outdoor airborne particles. An in vitro study on mutagenic potential and toxicological implications.

    OpenAIRE

    Houdt, van, R.

    1988-01-01

    IntroductionAir pollution components are present as gases and as particulate matter. As particle deposition takes place in various parts of the respiratory system particulate matter may have other toxicological implications than gaseous pollutants, which all may penetrate in the lower part of the respiratory tract. In addition, suspended particulate matter represents a group of pollutants of variable physical as well as chemical composition. Therefore airborne particulate matter cannot be reg...

  12. Assessment of oxidative DNA damage formation by organic complex mixtures from airborne particles PM10

    Czech Academy of Sciences Publication Activity Database

    Gábelová, A.; Valovičová, Z.; Lábaj, J.; Bačová, G.; Binková, Blanka; Farmer, P. B.

    2007-01-01

    Roč. 620, 1-2 (2007), s. 135-144. ISSN 0027-5107 Grant ostatní: EU(EU) 2000-00091 Institutional research plan: CEZ:AV0Z50390512 Source of funding: R - rámcový projekt EK Keywords : airborne particles PM10 * oxidative DNA damage * 8-oxoguanine Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 4.159, year: 2007

  13. Airborne Release of Particles in Overheating Incidents Involving Plutonium Metal and Compounds

    International Nuclear Information System (INIS)

    Ever-increasing utilization of nuclear fuels will result in wide-scale plutonium recovery processing, reconstitution of fuels, transportation, and extensive handling of this material. A variety of circumstances resulting in overheating and fires involving plutonium may occur, releasing airborne particles. This work describes the observations from a study in which the airborne release of plutonium and its compounds was measured during an exposure of the material of interest containing plutonium to temperatures which may result from fires. Aerosol released from small cylinders of metallic plutonium ignited in air at temperatures from 410 to 650°C ranged from 3 x 10-6 to 5 x 10-5 wt%. Particles smaller than 15μm in diameter represented as much as 0.03% of the total released. Large plutonium pieces weighing from 456 to 1770 g were ignited and allowed to oxidize completely in air with a velocity of around 500 cm/sec. Release rates of from 0.0045 to 0.032 wt% per hour were found. The median mass diameter of airborne material was 4 μm. Quenching the oxidation with magnesium oxide sand reduced the release to 2.9 X 10-4 wt% per hour. Many experiments were carried out in which plutonium compounds as powders were heated at temperatures ranging from 700 to 1000°C with several air flows. Release rates ranged from 5 x 10-8 to 0.9 wt% per hour, depending upon the compound and the conditions imposed. The airborne release from boiling solutions of plutonium nitrate were roughly related to energy of boiling, and ranged from 4 x 10-4 to 2 x 10-1 % for the evaporation of 90% of the solution. The fraction airborne when combustibles contaminated with plutonium are burned is under study. The data reported can be used in assessing the consequences of off-standard situations involving plutonium and its compounds in fires. (author)

  14. Predicting emissions of SVOCs from polymeric materials and their interaction with airborne particles.

    Science.gov (United States)

    Xu, Ying; Little, John C

    2006-01-15

    A model that predicts the emission rate of volatile organic compounds (VOCs) from building materials is extended and used to predict the emission rate of semivolatile organic compounds (SVOCs) from polymeric materials. Reasonable agreement between model predictions and gas-phase di-2-ethylhexyl phthalate (DEHP) concentrations is achieved using data collected in a previous experimental study that measured emissions of DEHP from vinyl flooring in two very different chambers. While emissions of highly volatile VOCs are subject to "internal" control (the material-phase diffusion coefficient), emissions of the very low volatility SVOCs are subject to "external" control (partitioning into the gas phase, the convective mass-transfer coefficient, and adsorption onto interior surfaces). The effect of SVOCs partitioning onto airborne particles is also examined. The DEHP emission rate is increased when the gas-phase concentration is high, and especially when partitioning to the airborne particles is strong. Airborne particles may play an important role in inhalation exposure as well as in transporting SVOCs well beyond the source. Although more rigorous validation is needed, the model should help elucidate the mechanisms governing emissions of phthalate plasticizers, brominated flame retardants, biocides, and other SVOCs from a wide range of building materials and consumer products. PMID:16468389

  15. Intercomparison of 15 Aerodynamic Particle Size Spectrometers (APS 3321): Uncertainties in Particle Sizing and Number Size Distribution.

    Czech Academy of Sciences Publication Activity Database

    Pfeifer, S.; Müller, T.; Weinhold, K.; Zíková, Naděžda; dos Santos, S.M.; Marinoni, A.; Bischof, O.F.; Kykal, C.; Ries, L.; Meinhardt, F.; Aalto, P.; Mihalopoulos, N.; Wiedensohler, A.

    2016-01-01

    Roč. 9, č. 4 (2016), s. 1545-1551. ISSN 1867-1381 EU Projects: European Commission(XE) 262254 - ACTRIS Institutional support: RVO:67985858 Keywords : counting efficiency * aerodynamic particle size spectrometers * laboratory study Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.929, year: 2014

  16. Total airborne mold particle sampling: evaluation of sample collection, preparation and counting procedures, and collection devices.

    Science.gov (United States)

    Godish, Diana; Godish, Thad

    2008-02-01

    This study was conducted to evaluate (i) procedures used to collect, prepare, and count total airborne mold spore/particle concentrations, and (ii) the relative field performance of three commercially available total airborne mold spore/particle sampling devices. Differences between factory and laboratory airflow calibration values of axial fan-driven sampling instruments (used in the study) indicated a need for laboratory calibration using a mass flow meter to ensure that sample results were accurately calculated. An aniline blue-amended Calberla's solution adjusted to a pH of 4.2-4.4 provided good sample mounting/counting results using Dow Corning high vacuum grease, Dow Corning 280A adhesive, and Dow Corning 316 silicone release spray for samples collected using mini-Burkard and Allergenco samplers. Count variability among analysts was most pronounced in 5% counts of relatively low mold particle deposition density samples and trended downward with increased count percentage and particle deposition density. No significant differences were observed among means of 5, 10, and 20% counts and among analysts; a significant interaction effect was observed between analysts' counts and particle deposition densities. Significantly higher mini-Burkard and Air-O-Cell total mold spore/particle counts for 600x vs. 400x (1.9 and 2.3 x higher, respectively), 1000x vs. 600x (1.9 and 2.2 x higher, respectively) and 1000x vs. 400x (3.6 and 4.6 x higher, respectively) comparisons indicated that 1000x magnification counts best quantified total airborne mold spore/particles using light microscopy, and that lower magnification counts may result in unacceptable underreporting of airborne mold spore/particle concentrations. Modest but significantly higher (1.2x) total mold spore concentrations were observed with Allergenco vs. mini-Burkard samples collected in co-located, concurrently operated sampler studies; moderate but significantly higher mini-Burkard count values (1.4x) were

  17. Approximation for the absorption coefficient of airborne atmospheric aerosol particles in terms of measurable bulk properties

    OpenAIRE

    HÄNEL, GOTTFRIED; Dlugi, Ralph

    2011-01-01

    The absorption coefficient of airborne atmospheric aerosol particles can be approximated by where λ is the wavelength of radiation, n — ik is the mean complex refractive index, ρ the mean bulk density, and M/Vk the mass of the particles per unit volume of air. This approximation gives good results at relative humidities between 0 and 0.95 for the wavelengths of radiation between 0.55 μm and 2.0 μm and between 9.25 μm and 12.0 μm. Basing on this approximation it is possible to determine the s...

  18. A review of airborne particle sampling with special reference to long-lived radioactive dust

    International Nuclear Information System (INIS)

    This report reviews some basic aspects related to the sampling of airborne particles with special reference to Long-Lived Radioactive Dust (LLRD). The report covers a number of areas of practical interest such as the production of aerosols, the dynamics of suspended particles, the physical and chemical characteristics and properties of dust clouds, and the inhalation and measurement of dust. It is followed with a brief review of dust sampling instrumentation, and with a short account of the work done on LLRD in Canada with a few references to work done outside this country. (34 figs., 7 tabs., 117 refs.)

  19. The generation of diesel exhaust particle aerosols from a bulk source in an aerodynamic size range similar to atmospheric particles

    Directory of Open Access Journals (Sweden)

    Daniel J Cooney

    2008-08-01

    Full Text Available Daniel J Cooney1, Anthony J Hickey21Department of Biomedical Engineering; 2School of Pharmacy, University of North Carolina, Chapel Hill, NC, USAAbstract: The influence of diesel exhaust particles (DEP on the lungs and heart is currently a topic of great interest in inhalation toxicology. Epidemiological data and animal studies have implicated airborne particulate matter and DEP in increased morbidity and mortality due to a number of cardiopulmonary diseases including asthma, chronic obstructive pulmonary disorder, and lung cancer. The pathogeneses of these diseases are being studied using animal models and cell culture techniques. Real-time exposures to freshly combusted diesel fuel are complex and require significant infrastructure including engine operations, dilution air, and monitoring and control of gases. A method of generating DEP aerosols from a bulk source in an aerodynamic size range similar to atmospheric DEP would be a desirable and useful alternative. Metered dose inhaler technology was adopted to generate aerosols from suspensions of DEP in the propellant hydrofluoroalkane 134a. Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm. Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process. Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene in the particles resulting from the aerosolization process.Keywords: diesel exhaust particles, aerosol, inhalation toxicology

  20. Ultrasonic attenuation model for measuring particle size and inverse calculation of particle size distribution in mineral slurries

    Institute of Scientific and Technical Information of China (English)

    HE Gui-chun; NI Wen

    2006-01-01

    Based on various ultrasonic loss mechanisms, the formula of the cumulative mass percentage of minerals with different particle sizes was given, with which the particle size distribution was integrated into an ultrasonic attenuation model. And then the correlations between the ultrasonic attenuation and the pulp density, and the particle size were obtained. The derived model was combined with the experiment and the analysis of experimental data to determine the inverse model relating ultrasonic attenuation coefficient with size distribution. Finally, an optimization method of inverse parameter, genetic algorithm was applied for particle size distribution. The results of inverse calculation show that the precision of measurement was high.

  1. Counting and measuring particles sized from soot to pollen

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    For number concentration measurements of superfine particles a condensation nucleus counter (CNC) is frequently used. The combination of a new CNC module with a white light aerosol spectrometer and a passive collector makes possible accurate time-resolved determination of particle number within the overall size range of 10 nm to 40 μm and at concentrations up to 105 particles/cm3. With the aerosol spectrometer a high time-resolved particle size determination is also possible in the size range of 0.3-40 μm up to the same high number concentrations of 105 particles/cm3.

  2. A Lagrangian particle model to predict the airborne spread of foot-and-mouth disease virus

    Science.gov (United States)

    Mayer, D.; Reiczigel, J.; Rubel, F.

    Airborne spread of bioaerosols in the boundary layer over a complex terrain is simulated using a Lagrangian particle model, and applied to modelling the airborne spread of foot-and-mouth disease (FMD) virus. Two case studies are made with study domains located in a hilly region in the northwest of the Styrian capital Graz, the second largest town in Austria. Mountainous terrain as well as inhomogeneous and time varying meteorological conditions prevent from application of so far used Gaussian dispersion models, while the proposed model can handle these realistically. In the model, trajectories of several thousands of particles are computed and the distribution of virus concentration near the ground is calculated. This allows to assess risk of infection areas with respect to animal species of interest, such as cattle, swine or sheep. Meteorological input data like wind field and other variables necessary to compute turbulence were taken from the new pre-operational version of the non-hydrostatic numerical weather prediction model LMK ( Lokal-Modell-Kürzestfrist) running at the German weather service DWD ( Deutscher Wetterdienst). The LMK model provides meteorological parameters with a spatial resolution of about 2.8 km. To account for the spatial resolution of 400 m used by the Lagrangian particle model, the initial wind field is interpolated upon the finer grid by a mass consistent interpolation method. Case studies depict a significant influence of local wind systems on the spread of virus. Higher virus concentrations at the upwind side of the hills and marginal concentrations in the lee are well observable, as well as canalization effects by valleys. The study demonstrates that the Lagrangian particle model is an appropriate tool for risk assessment of airborne spread of virus by taking into account the realistic orographic and meteorological conditions.

  3. Dependence of strength on particle size in graphite

    International Nuclear Information System (INIS)

    The strength to particle size relationship for specially fabricated graphites has been demonstrated and rationalized using fracture mechanics. In the past, similar studies have yielded empirical data using only commercially available material. Thus, experimental verification of these relationships has been difficult. However, the graphites of this study were fabricated by controlling the particle size ranges for a series of isotropic graphites. All graphites that were evaluated had a constant 1.85 g/cm3 density. Thus, particle size was the only variable. This study also considered the particle size effect on other physical properties; coefficient of thermal expansion (CTE), electrical resistivity, fracture strain, and Young's modulus

  4. Finite size effect of harmonic measure estimation in a DLA model: Variable size of probe particles

    OpenAIRE

    Menshutin, Anton Yu.; Shchur, Lev N.; Vinokour, Valery M.

    2008-01-01

    A finite size effect in the probing of the harmonic measure in simulation of diffusion-limited aggregation (DLA) growth is investigated. We introduce a variable size of probe particles, to estimate harmonic measure and extract the fractal dimension of DLA clusters taking two limits, of vanishingly small probe particle size and of infinitely large size of a DLA cluster. We generate 1000 DLA clusters consisting of 50 million particles each, using an off-lattice killing-free algorithm developed ...

  5. The biological response to nanometre-sized polymer particles.

    Science.gov (United States)

    Liu, Aiqin; Richards, Laura; Bladen, Catherine L; Ingham, Eileen; Fisher, John; Tipper, Joanne L

    2015-09-01

    Recently, nanometre-sized UHMWPE particles generated from hip and knee replacements have been identified in vitro and in vivo. UHMWPE particles in the 0.1-1.0μm size range have been shown to be more biologically active than larger particles, provoking an inflammatory response implicated in late aseptic loosening of total joint replacements. The biological activity of nanometre-sized particles has not previously been studied. The biological response to clinically-relevant UHMWPE wear particles including nanometre-sized and micrometre-sized, along with polystyrene particles (FluoSpheres 20nm, 60nm, 200nm and 1.0μm), and nanometre-sized model polyethylene particles (Ceridust 3615®), was determined in terms of osteolytic cytokine release from primary human peripheral blood mononuclear cells (PBMNCs). Nanometre-sized UHMWPE wear particles, nanometre-sized Ceridust 3615® and 20nm FluoSpheres had no significant effect on TNF-α, IL-1β, IL-6 and IL-8 release from PBMNCs at a concentration of 100μm(3) particles per cell after 12 and 24h. The micrometre-size UHMWPE wear particles (0.1-1.0μm) and 60nm, 200nm and 1.0μm FluoSpheres caused significantly elevated osteolytic cytokine release from PBMNCs. These results indicated that particles below circa 50nm fail to activate PBMNCs and that particle size, composition and morphology played a crucial role in cytokine release by particle stimulated macrophages. PMID:26004221

  6. Preference of food particle size among several urban ant species.

    Science.gov (United States)

    Hooper-Bùi, Linda M; Appel, Arthur G; Rust, Michael K

    2002-12-01

    Appropriate particle size may be a critical characteristic for effective granular ant baits. We examined the particle size preference of six species of pest ants to an anchovy-based bait. We also examined head capsule widths of Argentine ants, Linepithema humile (Mayr) (mean = 0.54 mm), California harvester ants, Pogonomyrmex californicus (Buckley) (mean = 1.63 mm), red imported fire ants, Solenopsis invicta Buren (mean = 0.9 mm), and southern fire ants, Solenopsis xyloni McCook (mean = 0.76 mm) and compared them with the first and second most preferred particle size. There were differences between particle size of which the most mass was removed and of which there were more particles removed by ants. California Argentine ants, southern fire ants, and Alabama Argentine ants removed more 840 to 1,000-microm particle mass of the anchovy diet but had more visits to dishes containing 420 to 590 microm particles. California harvester ants and Allegheny mound ants, Formica spp., removed more >2,000 microm particle mass but visited dishes containing 1,000 to 2,000 microm particles more often. Red imported fire ants also removed more >2,000 microm particle mass but visited dishes with 590 to 840-microm particles most often. Pharaoh ants, Monomorium pharaonis (L.), removed and visited 420 to 590-microm particles more than any other size. A linear regression model determined that particle size preferred by each ant species relates to forager head width. The majority of particles of commercial ant bait, including Amdro, Ascend, Award, Bushwhacker, Max Force with fipronil, and old and new formulations of Max Force with hydramethylnon, were 1,000 to 2,000 microm, but the majority of Niban particles were ant baits to fit the particle size preference of each pest ant species may increase the efficacy of ant baits. PMID:12539835

  7. Selective follicular targeting by modification of the particle sizes.

    Science.gov (United States)

    Patzelt, Alexa; Richter, Heike; Knorr, Fanny; Schäfer, Ulrich; Lehr, Claus-Michael; Dähne, Lars; Sterry, Wolfram; Lademann, Juergen

    2011-02-28

    Hair follicles represent interesting target sites for topically applied substances such as topical vaccinations or agents used in the field of regenerative medicine. In recent years, it could be shown that particles penetrate very effectively into the hair follicles. In the present study, the influence of particle size on the follicular penetration depths was examined. The penetration depths of two different types of particles sized 122 to 1000 nm were determined in vitro on porcine skin. The results revealed that the particles of medium size (643 and 646 nm, respectively) penetrated deeper into the porcine hair follicles than smaller or larger particles. It was concluded that by varying the particle size, different sites within the porcine hair follicle can be targeted selectively. For the human terminal hair follicle, the situation can be expected to be similar due to a similar size ratio of the hair follicles. PMID:21087645

  8. Particle size dependent chemistry from laser ablation of brass.

    Science.gov (United States)

    Liu, Chunyi; Mao, Xianglei; Mao, Sam S; Greif, Ralph; Russo, Richard E

    2005-10-15

    The proportion of zinc and copper in particles formed by laser ablation of brass was found to vary with the particle diameter. Energy-dispersive X-ray analysis showed that smaller particles were zinc enhanced while larger particles were composed mostly of copper. A model based on condensation of vapor onto large droplets ejected from a melted liquid layer is proposed to describe the change in particle composition versus size. PMID:16223257

  9. The physicochemical characterisation of microscopic airborne particles in south Wales: A review of the locations and methodologies

    International Nuclear Information System (INIS)

    As part of the NERC-URGENT thematic programme, research was undertaken into the physicochemistry and bioreactivity of microscopic airborne particulate matter in south Wales. This paper reviews the collecting and characterisation methods used in the research; some of the results obtained are shown as examples. Four main collecting locations were chosen: Cardiff (urban); Port Talbot (urban/industrial); Park Slip West coal opencast pit (industrial/rural); the Black Mountains (rural/background). Collections initially used a 30-l/min Negretti PM1 filter collection system, however in the later stages of the project increased use was made of a 1100-l/min impaction system (nicknamed the super-sucker). This latter device was developed at Harvard University USA, however was adapted and optimised at Cardiff University. Methods for the extraction of PM1 off polycarbonate filters and polyurethane substrates were developed, with particular attention being paid to minimise physical or chemical changes during the extraction, and the extracts being in an appropriate state for bioreactivity assessment. Physicochemical characterisation of the PM1 included the empirical measurement of shape and size using electron microscopy and semi-automated image analysis. The determinations of the water-soluble and -insoluble chemical components were undertaken by ion chromatography and inductive coupled plasma-mass spectrometry. The bioreactivity of south Wales airborne particles is not covered by this review

  10. Production of sized particles of uranium oxides and uranium oxyfluorides

    International Nuclear Information System (INIS)

    A process is claimed for converting uranium hexafluoride (UF6) to uranium dioxide (UO2) of a relatively large particle size in a fluidized bed reactor by mixing uranium hexafluoride with a mixture of steam and hydrogen and by preliminary reacting in an ejector gaseous uranium hexafluoride with steam and hydrogen to form a mixture of uranium and oxide and uranium oxyfluoride seed particles of varying sizes, separating the larger particles from the smaller particles in a cyclone separator, recycling the smaller seed particles through the ejector to increase their size, and introducing the larger seed particles from the cyclone separator into a fluidized bed reactor where the seed particles serve as nuclei on which coarser particles of uranium dioxide are formed. 9 claims, 2 drawing figures

  11. Occupational exposure to airborne particles and other pollutants in an aviation base

    International Nuclear Information System (INIS)

    The occupational exposure to airborne particles and other pollutants in a high performance jet engine airport was investigated. Three spatial scales were considered: i) a downwind receptor site, ii) close to the airstrip, iii) personal monitoring. Particle number, surface area, mass concentrations and distributions were measured as well as inorganic and organic fractions, ionic fractions and Polycyclic Aromatic Hydrocarbons. Particle number distribution measured at a receptor site presents a mode of 80 nm and an average total concentration of 6.5 × 103 part. cm−3; the chemical analysis shows that all the elements may be attributed to long-range transport from the sea. Particle number concentrations in the proximity of the airstrip show short term peaks during the working day mainly related to takeoff, landing and pre-flight operations of jet engines. Personal exposure of workers highlights a median number concentration of 2.5 × 104 part. cm−3 and 1.7 × 104 part. cm−3 for crew chief and hangar operator. - Highlights: ► Air quality measures were performed at different spatial scales in an aviation base. ► Exposure to Polycyclic Aromatic Hydrocarbons was estimated. ► Particles at downwind receptor site show a marine origin typical of a coastal site. ► Main exposure peaks are related to pre-flight operations of jet engine aircrafts. ► Crew chief are exposed to highest concentrations even if these were not worrisome. - A negligible impact of a high performance jet engine airport, in terms of airborne particles and other pollutants, was measured through an experimental campaign at three spatial scales.

  12. Optical manipulation of airborne particles using flexible dual-beam trap

    Czech Academy of Sciences Publication Activity Database

    Brzobohatý, Oto; Šiler, Martin; Zemánek, Pavel

    Bellingham: SPIE, 2012 - (Dholakia, K.; Spalding, G.), 84582C:1-7 ISBN 978-0-8194-9175-6. [Optical Trapping and Optical Micromanipulation IX. San Diego (US), 12.08.2012-16.08.2012] R&D Projects: GA ČR GPP205/11/P294; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : Optical tweezers * Dual-beam trap * Standing wave trap * Spatial light modulator * Airborne particles * Droplets Subject RIV: BH - Optics, Masers, Lasers

  13. Turbulent particle deposition in a rectangular chamber: Study of the effect of particle size and ventilation regimes

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, Yoshio

    1996-04-01

    The interaction of aerosol particles with wall surfaces is important in modeling their behavior. This interaction is usually represented in theoretical models as a loss term. The loss rate is the rate at which particles deposit or react with the surfaces. This loss term is important in many branches of aerosol science including human health and indoor air quality. Increased surface deposition usually means lower concentrations of airborne particles and hence, lower exposure to the inhabitants. If the efficiency of the particle deposition is influenced by factors other than the particle size, such as a natural convection of the air, this has to be taken into account to evaluate the results. In this research, test aerosol sized from 15 nm to 3 {micro}m are produced by several different aerosol generators; the gas burner, the Collison nebulizer, the condensation aerosol generator, the orifice atomizer and the Vibrating Orifice Aerosol Generator (VOAG). A rectangular chamber whose dimensions are 75 x 75 x 180 cm{sup 3} was used in this study. The particles were injected into the chamber, with a known ventilation and the concentration decay was monitored by the Ultrafine Condensation Particle Counter (UCPC) and Optical Particle Counter (OPC). During the measurement, the air inside the chamber is moved by natural convection and ventilation effect. The results shows that the particle loss rate under the higher air exchange rate is larger and this is not only due to air exchange itself but also the wall deposition. The theoretical model presented by Benes and Holub (1996) agree with the experimental data better than the Crump and Seinfield (1981) model with the hypothesis of Plandtl`s mixing length. 118 refs.

  14. Calculation method for particle mean diameter and particle size distribution function under dependent model algorithm

    Institute of Scientific and Technical Information of China (English)

    Hong Tang; Xiaogang Sun; Guibin Yuan

    2007-01-01

    In total light scattering particle sizing technique, the relationship among Sauter mean diameter D32, mean extinction efficiency Q, and particle size distribution function is studied in order to inverse the mean diameter and particle size distribution simply. We propose a method which utilizes the mean extinction efficiency ratio at only two selected wavelengths to solve D32 and then to inverse the particle size distribution associated with (Q) and D32. Numerical simulation results show that the particle size distribution is inversed accurately with this method, and the number of wavelengths used is reduced to the greatest extent in the measurement range. The calculation method has the advantages of simplicity and rapidness.

  15. Particle size distribution in ferrofluid macro-clusters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wah-Keat, E-mail: wklee@bnl.gov [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700S. Cass Avenue, Argonne, IL 60439 (United States); Ilavsky, Jan [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700S. Cass Avenue, Argonne, IL 60439 (United States)

    2013-03-15

    Under an applied magnetic field, many commercial and concentrated ferrofluids agglomerate and form large micron-sized structures. Although large diameter particles have been implicated in the formation of these macro-clusters, the question of whether the particle size distribution of the macro-clusters are the same as the original fluid remains open. Some studies suggest that these macro-clusters consist of larger particles, while others have shown that there is no difference in the particle size distribution between the macro-clusters and the original fluid. In this study, we use X-ray imaging to aid in a sample (diluted EFH-1 from Ferrotec) separation process and conclusively show that the average particle size in the macro-clusters is significantly larger than those in the original sample. The average particle size in the macro-clusters is 19.6 nm while the average particle size of the original fluid is 11.6 nm. - Highlights: Black-Right-Pointing-Pointer X-ray imaging was used to isolate ferrofluid macro-clusters under an applied field. Black-Right-Pointing-Pointer Small angle X-ray scattering was used to determine particle size distributions. Black-Right-Pointing-Pointer Results show that macro-clusters consist of particles that are larger than average.

  16. Particle size distribution in ferrofluid macro-clusters

    International Nuclear Information System (INIS)

    Under an applied magnetic field, many commercial and concentrated ferrofluids agglomerate and form large micron-sized structures. Although large diameter particles have been implicated in the formation of these macro-clusters, the question of whether the particle size distribution of the macro-clusters are the same as the original fluid remains open. Some studies suggest that these macro-clusters consist of larger particles, while others have shown that there is no difference in the particle size distribution between the macro-clusters and the original fluid. In this study, we use X-ray imaging to aid in a sample (diluted EFH-1 from Ferrotec) separation process and conclusively show that the average particle size in the macro-clusters is significantly larger than those in the original sample. The average particle size in the macro-clusters is 19.6 nm while the average particle size of the original fluid is 11.6 nm. - Highlights: ► X-ray imaging was used to isolate ferrofluid macro-clusters under an applied field. ► Small angle X-ray scattering was used to determine particle size distributions. ► Results show that macro-clusters consist of particles that are larger than average.

  17. Methods for determining particle size distribution and growth rates between 1 and 3 nm using the Particle Size Magnifier

    CERN Document Server

    Lehtipalo, Katrianne; Kontkanen, Jenni; Kangasluoma, Juha; Franchin, Alessandro; Wimmer, Daniela; Schobesberger, Siegfried; Junninen, Heikki; Petäjä, Tuukka; Sipilä, Mikko; Mikkilä, Jyri; Vanhanen, Joonas; Worsnop, Douglas R; Kulmala, Markku

    2014-01-01

    The most important parameters describing the atmospheric new particle formation process are the particle formation and growth rates. These together determine the amount of cloud condensation nuclei attributed to secondary particle formation. Due to difficulties in detecting small neutral particles, it has previously not been possible to derive these directly from measurements in the size range below about 3 nm. The Airmodus Particle Size Magnifier has been used at the SMEAR II station in Hyytiälä, southern Finland, and during nucleation experiments in the CLOUD chamber at CERN for measuring particles as small as about 1 nm in mobility diameter. We developed several methods to determine the particle size distribution and growth rates in the size range of 1–3 nm from these data sets. Here we introduce the appearance-time method for calculating initial growth rates. The validity of the method was tested by simulations with the Ion-UHMA aerosol dynamic model.

  18. Particle Size: A sediment tracing challenge or opportunity?

    Science.gov (United States)

    Laceby, J. Patrick; Evrard, Olivier

    2016-04-01

    Tracing sediment back to their sources with biogeochemical fingerprints involves multiple assumptions. One of the most fundamental assumptions is the conservative behavior of tracer properties during sediment generation, transportation, and deposition processes. Essentially, the biogeochemical fingerprints used to trace sediment must remain constant, or conservative, during these erosion processes, or they must vary in a predictable way. At the core of this assumption of conservative behavior are potential particle size impacts. Owing to the significance of particle size for sediment tracing research, we believe it is important to present an overview of past and present techniques used to address particle size, along with possibilities for future research. The two primary approaches utilized to address particle size impacts are fractionation (e.g., researchers applying the tributary tracing approach or sampling sediment generated directly on hillslopes may potentially address particle size impacts in their sampling design. Although these approaches have been presented in the literature, their effectiveness has yet to be determined. For the future, we boldly suggest that there are likely situations where particle size may be potentially used as a fingerprint in and of itself. Indeed, potential particle size impacts are directly related to the biogeochemical fingerprints used to trace sediments and we believe that there is a fantastic opportunity to obtain further sediment source information through comprehensively investigating and unravelling inherent particle size complexities.

  19. Effect of particle size on enzymatic hydrolysis of pretreated Miscanthus

    Science.gov (United States)

    Particle size reduction is a crucial factor in transportation logistics as well as cellulosic conversion. The effect of particle size on enzymatic hydrolysis of pretreated Miscanthus x giganteus was determined. Miscanthus was ground using a hammer mill equipped with screens having 0.08, 2.0 or 6.0...

  20. Particle size control of detergents in mixed flow spray dryers

    Directory of Open Access Journals (Sweden)

    Mark Jonathan Crosby

    2015-03-01

    Full Text Available Particle size is a key quality parameter of a powder detergent as it determines its performance, the bulk density and the look and feel of the product. Consequently, it is essential that particle size is controlled to ensure the consistency of performance when comparing new formulations. The majority of study reported in the literature relating to particle size control, focuses on the spray produced by the atomisation technique. One approach advocated to achieve particle size control is the manipulation of the ratio of the mass slurry rate and mass flow rate of gas used for atomisation. Within this study, ratio control was compared with an automatic cascade loop approach using online measurements of the powder particle size on a small-scale pilot plant. It was concluded that cascade control of the mean particle size, based on manipulating the mass flow rate of gas, resulted in tighter, more responsive control. The effect of a ratio change varied with different formulations and different slurry rates. Furthermore, changes in slurry rate caused complications, as the impact on particle size growth in the dryer is non-linear and difficult to predict. The cascade loop enables further study into the effect of particle size on detergent performance.

  1. Continuum radiation analysis of size distributed ensembles of char particles

    Energy Technology Data Exchange (ETDEWEB)

    Zarkova, L.P.; Pirgov, P.S. [Bulgarian Academy of Sciences, Sofia (Bulgaria). Inst. of Electronics; Vasilieva, I.A. [Inst. of High Temperatures, Moscow (Russian Federation); Banin, V.E.; Moors, J.H.J.; Veefkind, A. [Technische Hogeschool Eindhoven (Netherlands). Lab. for Fluid Dynamics and Heat Transfer

    1997-12-31

    Continuum radiation emitted by char particles has been collected during shock tube experiments. Since the particles have different sizes their cooling rates, their temperatures and emissivities are different. A method is presented to determine the kinetic parameters of char combustion taking into account this complication, when the initial size distribution is determined independently. Results are presented and their accuracy will be discussed. (orig.)

  2. Magnetic Properties of Nanometer-sized Crystalline and Amorphous Particles

    DEFF Research Database (Denmark)

    Mørup, Steen; Bødker, Franz; Hansen, Mikkel Fougt; Jiang, Jianzhong

    Amorphous transition metal-metalloid alloy particles can be prepared by chemical preparation techniques. We discuss the preparation of transition metal-boron and iron-carbon particles and their magnetic properties. Nanometer-sized particles of both crystalline and amorphous magnetic materials are...

  3. Synthesis of size-controlled Bi particles by electrochemical deposition

    Indian Academy of Sciences (India)

    C N Tharamani; H C Thejaswini; S Sampath

    2008-06-01

    Small sized bismuth particles are prepared by an electrochemical method using a triple voltage pulse technique. The bath composition and electrochemical parameters are optimized to yield monodisperse particles. The particles have been characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, UV-visible spectroscopy and X-ray diffraction technique. The particles, as deposited, are highly crystalline in nature and the particle size and shape get tuned depending on the conditions of deposition.

  4. Stability and size of particle pairs in complex plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Nosenko, V., E-mail: V.Nosenko@dlr.de [Deutsches Zentrum für Luft- und Raumfahrt, Forschungsgruppe Komplexe Plasmen, D-82234 Weßling (Germany); Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching (Germany); Ivlev, A. V.; Kompaneets, R. [Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching (Germany); Morfill, G. [Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching (Germany); Centre for Plasma Science and Technology, BMSTU, Moscow (Russian Federation)

    2014-11-15

    Particle pairing in a complex plasma was experimentally studied with the emphasis on pair spatial extent and stability. Micron-size particles were suspended in the (pre)sheath area above the lower electrode in a capacitively coupled radio-frequency discharge in argon. They formed vertical pairs due to the ion wakes created by the flow of ions past particles. We discuss the confinement mechanism for the lower particle, resulting from a combination of the wake field and the field of non-uniform sheath. A model of particle pairs is proposed, which provides good description for the dependence of pair size and stability on experimental parameters.

  5. Do finite size neutrally buoyant particles cluster?

    CERN Document Server

    Fiabane, Lionel; Pinton, Jean-Francois; Monchaux, Romain; Cartellier, Alain; Bourgoin, Mickael

    2012-01-01

    We investigate the preferential concentration of particles which are neutrally buoyant but with a diameter significantly larger than the dissipation scale of the carrier flow. Such particles are known not to behave as flow tracers (Qureshi et al., Phys. Re. Lett. 2007) but whether they do cluster or not remains an open question. For this purpose, we take advantage of a new turbulence generating apparatus, the Lagrangian Exploration Module which produces homogeneous and isotropic turbulence in a closed water flow. The flow is seeded with neutrally buoyant particles with diameter 700\\mum, corresponding to 4.4 to 17 times the turbulent dissipation scale when the rotation frequency of the impellers driving the flow goes from 2 Hz to 12 Hz, and spanning a range of Stokes numbers from 1.6 to 24.2. The spatial structuration of these inclusions is then investigated by a Voronoi tesselation analysis, as recently proposed by Monchaux et al. (Phys. Fluids 2010), from images of particle concentration field taken in a las...

  6. Influence of particle size on diffusion-limited aggregation.

    Science.gov (United States)

    Tan, Z J; Zou, X W; Zhang, W B; Jin, Z Z

    1999-11-01

    The influence of particle size on diffusion-limited aggregation (DLA) has been investigated by computer simulations. For DLA clusters consisting of two kinds of particles with different sizes, when large particles are in the minority, the patterns of clusters appear asymmetrical and nonuniform, and their fractal dimensions D(f) increase compared with one-component DLA. With increasing size of large particles, D(f) increases. This increase can be attributed to two reasons: one is that large particles become new growth centers; the other is the big masses of large particles. As the concentration ratio x(n) of large particles increases, D(f) will reach a maximum value D(f(m)) and then decrease. When x(n) exceeds a certain value, the morphology and D(f) of the two-component DLA clusters are similar to those of one-component DLA clusters. PMID:11970534

  7. A hybrid mathematical model for controlling particle size, particle size distribution, and color properties of toner particles

    Science.gov (United States)

    Ataeefard, Maryam; Shadman, Alireza; Saeb, Mohammad Reza; Mohammadi, Yousef

    2016-08-01

    A mathematical modeling approach was proposed combining the capabilities of response surface methodology (RSM) and desirability function (DF) and implemented successfully in production of printing toner particles. Toner powders were systematically synthesized through suspension copolymerization process. Applying RSM, a series of experiments were designed and toner particles were prepared and the effects of monomer ratio, colorant and surfactant content on the particle size (PS), particle size distribution (PSD), thermal and colorimetric properties (∆ E) of the resulting toner were monitored and discussed. The second-order models corresponding to each target characteristic, i.e., PS, PSD, and ∆ E of different types of toner powders, were obtained by individual optimization to express variation of each property in terms of polymerization parameters. Applying statistical calculations, the best reduced models were identified to be fed in the second step of optimization. Since toners with appropriate PS, PSD, and CP were needed, we applied multi-objective optimization based on DF approach. The results show that exact tuning of toner properties is closely possible with the aid of hybrid mathematical model developed in this work. Noticeably, desirabilities are very close to 100 %.

  8. Stability of MC Carbide Particles Size in Creep Resisting Steels

    Directory of Open Access Journals (Sweden)

    Vodopivec, F.

    2006-01-01

    Full Text Available Theoretical analysis of the dependence microstructure creep rate. Discussion on the effects of carbide particles size and their distribution on the base of accelerated creep tests on a steel X20CrMoV121 tempered at 800 °C. Analysis of the stability of carbide particles size in terms of free energy of formation of the compound. Explanation of the different effect of VC and NbC particles on accelerated creep rate.

  9. Nanometer Sized Silver Particles Embedded Silica Particles—Spray Method

    OpenAIRE

    Karunagaran B; Nimma Elizabeth R.; Gnana kumar G; Nahm KeeSuk

    2009-01-01

    Abstract Spherical shaped, nanometer to micro meter sized silica particles were prepared in a homogeneous nature by spray technique. Silver nanoparticles were produced over the surface of the silica grains in a harmonized manner. The size of silver and silica particles was effectively controlled by the precursors and catalysts. The electrostatic repulsion among the silica spheres and the electro static attraction between silica spheres and silver particles make the synchronized structure of t...

  10. Airborne particulate endocrine disrupting compounds in China: Compositions, size distributions and seasonal variations of phthalate esters and bisphenol A

    Science.gov (United States)

    Li, Jianjun; Wang, Gehui

    2015-03-01

    Phthalate esters and bisphenol A (BPA) are endocrine disrupting compounds (EDCs) and ubiquitously occur in the environment. In the past decade we have characterized atmospheric organic aerosols from various environments (e.g., urban, rural, mountain and marine) of East Asia on a molecular level, but not investigated EDCs in the samples. In the current study we re-analyzed our database for concentrations, compositions and size distributions of phthalates and BPA and compared with those in the literature to improve the understanding on air pollution status in China. Our results showed that airborne particulate phthalates and BPA are 63-1162 ng m- 3 and 1.0-20 ng m- 3 in the urban regions in China, respectively, being one to two orders of magnitude higher than those in the developed countries. Among the detected phthalates in Chinese urban areas, bis(2-ethylhexyl) phthalate (BEHP) is the predominant congener, contributing to 23-79% (ave. 53 ± 15%) of the total phthalates. Concentrations of phthalates and bisphenol A in Shanghai and Xi'an (two mega-cities in China) in 2009 were 3-84% lower than those in 2003, probably indicating a positive effect of the government's air pollution control in the recent years. Phthalates are higher in summer than in winter, because they are not chemically bonded to the polymeric matrix and more easily evaporate into the air under higher temperature conditions. Based on the size distribution observation, we found that diisobutyl and dibutyl phthalates mainly exist in coarse particles because of high volatilities, in contrast to BEHP and BPA, which are dominant in fine particles due to less volatility. Our results also indicate that BPA is mostly derived from the open burning of solid waste while phthalates are derived from both direct evaporation from the matrix and solid waste combustion.

  11. Size control of monodisperse nonporous silica particles by seed particle growth

    Institute of Scientific and Technical Information of China (English)

    Beibei Zhao; Caihua Tian; Yan Zhang; Tao Tang; Fengyun Wang

    2011-01-01

    Monodisperse nonporous silica particles were prepared by sol-precipitation via seed particle growth method, and the particle size, which varied from 1.0 to 4.7 μm, was strictly controlled in our experiment.The formation of secondary particles, which resulted in a multimodal distribution of particle size, was suppressed by changing tetraethoxysilane (TEOS) concentration and reaction temperature. Furthermore,the effect of adding small amounts of electrolyte to the hydrolysis mixture was examined.

  12. Size Segregation in Rapid Flows of Inelastic Particles with Continuous Size Distributions

    Institute of Scientific and Technical Information of China (English)

    LI Rui; ZHANG Duan-Ming; LI Zhi-Hao

    2012-01-01

    Two-dimensional numerical simulations are employed to gain insight into the segregation behavior of granular mixtures with a power-law particle size distribution in the presence of a granular temperature gradient.It is found that particles of all sizes move toward regions of low granular temperature.Species segregation is also observed.Large particles demonstrate a higher affinity for the low-temperature regions and accumulate in these cool regions to a greater extent than their smaller counterparts.Furthermore,the local particle size distribution maintains the same form as the overall (including all particles) size distribution.%Two-dimensional numerical simulations are employed to gain insight into the segregation behavior of granular mixtures with a power-law particle size distribution in the presence of a granular temperature gradient. It is found that particles of all sizes move toward regions of low granular temperature. Species segregation is also observed. Large particles demonstrate a higher affinity for the low-temperature regions and accumulate in these cool regions to a greater extent than their smaller counterparts. Furthermore, the local particle size distribution maintains the same form as the overall (including all particles) size distribution.

  13. The study on differentiated particle size sampling technology of aerosols

    International Nuclear Information System (INIS)

    This article introduces basic principle of differentiated particle size sampling technology of aerosols. This sampling technology is used to conduct a experimental research on the aerosols particles size distribution of uranium and radon and it's daughters. Experimental results showed that the part of radon and it's daughters aerosols particles size smaller than 0.43 μm reached 76.4%. The part of radon and it's daughters aerosols particles size less than 1 μm reached 96.3%. The part of uranium aerosol particles size larger than 4.7 μm under specific conditions is 94%, the part of aerosol particles size larger than 10 μm is 72%. According to the experiment's result, we designed a new sampling equipments that cutting size is 1 μm to collect samples of aerosols, and it is used in the separation efficiency experiments of 241Am aerosols. Experimental results showed that the separation efficiency of 241Am aerosols can reach 94.2%. Thus, using the differentiated particle size sampling technology to collect samples of plutonium aerosols, in the sampling process can reduce the effect of natural background aerosols. (authors)

  14. Reconciliation of coarse mode sea-salt aerosol particle size measurements and parameterizations at a subtropical ocean receptor site

    OpenAIRE

    Reid, J S; B. Brooks; Crahan, K. K.; De Leeuw, G.; E. A. Reid; Anderson, F.D.; D. A. Hegg; T. F. Eck; O'Neill, N.

    2006-01-01

    In August/September of 2001, the R/P FLIP and CIRPAS Twin Otter research aircraft were deployed to the eastern coast of Oahu, Hawaii, as part of the Rough Evaporation Duct (RED) experiment. Goals included the study of the air/sea exchange, turbulence, and sea-salt aerosol particle characteristics at the subtropical marine Pacific site. Here we examine coarse mode particle size distributions. Similar to what has been shown for airborne dust, optical particle counters such as the Forward Scatte...

  15. The impact of mass transfer limitations on size distributions of particle associated SVOCs in outdoor and indoor environments

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cong; Zhang, Yinping [Department of Building Science, Tsinghua University, Beijing (China); Weschler, Charles J., E-mail: weschlch@rwjms.rutgers.edu [Department of Building Science, Tsinghua University, Beijing (China); Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ (United States); International Center for Indoor Environment and Energy, Technical University of Denmark, Lyngby (Denmark)

    2014-11-01

    Semi-volatile organic compounds (SVOCs) partition between the gas phase and airborne particles. The size distribution of particle-associated SVOCs impacts their fate in outdoor and indoor environments, as well as human exposure to these compounds and subsequent health risks. Allen et al. (1996) previously proposed that the rate of mass transfer can impact polycyclic aromatic hydrocarbon (PAH) partitioning among different sized particles, especially for time scales relevant to urban aerosols. The present study quantitatively builds on this idea, presenting a model that incorporates dynamic SVOC/particle interaction and applying this model to typical outdoor and indoor scenarios. The model indicates that the impact of mass transfer limitations on the size distribution of a particle-associated SVOC can be evaluated by the ratio of the time to achieve gas–particle equilibrium relative to the residence time of particles. The higher this ratio, the greater the influence of mass transfer limitations on the size distribution of particle-associated SVOCs. The influence of such constraints is largest on the fraction of particle-associated SVOCs in the coarse mode (> 2 μm). Predictions from the model have been found to be in reasonable agreement with size distributions measured for PAHs at roadside and suburban locations in Japan. The model also quantitatively explains shifts in the size distributions of particle associated SVOCs compared to those for particle mass, and the manner in which these shifts vary with temperature and an SVOC's molecular weight. - Highlights: • Rate of mass transfer can impact SVOC partitioning among different sized particles. • Model was developed that incorporates dynamic SVOC/particle sorption. • Key parameters: mass-transfer coefficients, partition coefficient, residence time • Model explains observed SVOC size distribution shifts with temperature and MW. • Largest impact of mass transfer constraints: SVOC sorption to coarse

  16. The impact of mass transfer limitations on size distributions of particle associated SVOCs in outdoor and indoor environments

    International Nuclear Information System (INIS)

    Semi-volatile organic compounds (SVOCs) partition between the gas phase and airborne particles. The size distribution of particle-associated SVOCs impacts their fate in outdoor and indoor environments, as well as human exposure to these compounds and subsequent health risks. Allen et al. (1996) previously proposed that the rate of mass transfer can impact polycyclic aromatic hydrocarbon (PAH) partitioning among different sized particles, especially for time scales relevant to urban aerosols. The present study quantitatively builds on this idea, presenting a model that incorporates dynamic SVOC/particle interaction and applying this model to typical outdoor and indoor scenarios. The model indicates that the impact of mass transfer limitations on the size distribution of a particle-associated SVOC can be evaluated by the ratio of the time to achieve gas–particle equilibrium relative to the residence time of particles. The higher this ratio, the greater the influence of mass transfer limitations on the size distribution of particle-associated SVOCs. The influence of such constraints is largest on the fraction of particle-associated SVOCs in the coarse mode (> 2 μm). Predictions from the model have been found to be in reasonable agreement with size distributions measured for PAHs at roadside and suburban locations in Japan. The model also quantitatively explains shifts in the size distributions of particle associated SVOCs compared to those for particle mass, and the manner in which these shifts vary with temperature and an SVOC's molecular weight. - Highlights: • Rate of mass transfer can impact SVOC partitioning among different sized particles. • Model was developed that incorporates dynamic SVOC/particle sorption. • Key parameters: mass-transfer coefficients, partition coefficient, residence time • Model explains observed SVOC size distribution shifts with temperature and MW. • Largest impact of mass transfer constraints: SVOC sorption to coarse

  17. Acoustic emissions for particle sizing of powders through signal processing techniques

    Energy Technology Data Exchange (ETDEWEB)

    Bastari, A.; Cristalli, C.; Morlacchi, R.; Pomponi, E. [Loccioni Group (Italy)

    2011-04-15

    The present work introduces an innovative method for measuring particle size distribution of an airborne powder, based on the application of signal processing techniques to the acoustic emission signals produced by the impacts of the powder with specific metallic surfaces. The basic idea of the proposed methodology lies on the identification of the unknown relation between the acquired acoustic emission signals and the powder particle size distribution, by means of a multi-step procedure. In the first step, wavelet packet decomposition is used to extract useful features from the acoustic emission signals: the dimensionality of feature space is further reduced through multivariate data analysis techniques. As a final step, a neural network is properly trained to map the feature vector into the particle size distribution. The proposed solution has several advantages, such as low cost and low invasiveness which allow the system based on this technique to be easily integrated in pre-existing plants. It has been successfully applied to the PSD measurement of coal powder produced by grinding mills in a coal-fired power station, and the experimental results are reported in the paper. The measurement principle can also be applied to different particle sizing applications, whenever a solid powder is carried in air or in other gases.

  18. Concentration and Grist size spectrum of Airborne dust during operation of earth moving machineries of Alluvial soil

    Directory of Open Access Journals (Sweden)

    S. C. Ganguli

    1963-01-01

    Full Text Available Concentration and grist size spectrum of airborne dust generated by heavy earth moving machinery while operating on alluvial soil on the Indogangetic plain at Roorkee (29.52DegreeN, 77.53DegreeEN has been determined.

  19. Effect of Processing and Aging on Particle Size of Explosives

    Institute of Scientific and Technical Information of China (English)

    舒远杰; 刘世俊; 董海山; 郝莹; 詹春红; 陈捷

    2003-01-01

    Influence of such processes as molding powder production, pel-lets pressing and aging under different condit/ons on particle size of TATB ( 1,3,S-trlamino-2,4,6-trinltrobenzene ) and HMX (cyclotetramethylenetetranitramine) was experimentally studied. The results showed that parflele size of these explosives was greatly changed before and airier moldinu powder produc-tion, but for different size grade of explosive this change was not the same; pressing process had also great effect on explosive particle size, but before and after ageing process explosive par-tide size did not change seriously.

  20. Chamber bioaerosol study: human emissions of size-resolved fluorescent biological aerosol particles.

    Science.gov (United States)

    Bhangar, S; Adams, R I; Pasut, W; Huffman, J A; Arens, E A; Taylor, J W; Bruns, T D; Nazaroff, W W

    2016-04-01

    Humans are a prominent source of airborne biological particles in occupied indoor spaces, but few studies have quantified human bioaerosol emissions. The chamber investigation reported here employs a fluorescence-based technique to evaluate bioaerosols with high temporal and particle size resolution. In a 75-m(3) chamber, occupant emission rates of coarse (2.5-10 μm) fluorescent biological aerosol particles (FBAPs) under seated, simulated office-work conditions averaged 0.9 ± 0.3 million particles per person-h. Walking was associated with a 5-6× increase in the emission rate. During both walking and sitting, 60-70% or more of emissions originated from the floor. The increase in emissions during walking (vs. while sitting) was mainly attributable to release of particles from the floor; the associated increased vigor of upper body movements also contributed. Clothing, or its frictional interaction with human skin, was demonstrated to be a source of coarse particles, and especially of the highly fluorescent fraction. Emission rates of FBAPs previously reported for lecture classes were well bounded by the experimental results obtained in this chamber study. In both settings, the size distribution of occupant FBAP emissions had a dominant mode in the 3-5 μm diameter range. PMID:25704637

  1. Particle size and shape distributions of hammer milled pine

    Energy Technology Data Exchange (ETDEWEB)

    Westover, Tyler Lott [Idaho National Lab. (INL), Idaho Falls, ID (United States); Matthews, Austin Colter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Williams, Christopher Luke [Idaho National Lab. (INL), Idaho Falls, ID (United States); Ryan, John Chadron Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-04-01

    Particle size and shape distributions impact particle heating rates and diffusion of volatized gases out of particles during fast pyrolysis conversion, and consequently must be modeled accurately in order for computational pyrolysis models to produce reliable results for bulk solid materials. For this milestone, lodge pole pine chips were ground using a Thomas-Wiley #4 mill using two screen sizes in order to produce two representative materials that are suitable for fast pyrolysis. For the first material, a 6 mm screen was employed in the mill and for the second material, a 3 mm screen was employed in the mill. Both materials were subjected to RoTap sieve analysis, and the distributions of the particle sizes and shapes were determined using digital image analysis. The results of the physical analysis will be fed into computational pyrolysis simulations to create models of materials with realistic particle size and shape distributions. This milestone was met on schedule.

  2. Particle size measurement in intravenous fluids.

    Science.gov (United States)

    Haines-Nutt, R F; Munton, T J

    1984-08-01

    The level of particulate contamination in a range of large volume injections has been measured using electrical resistance (Coulter) and light blockage (HIAC) techniques. Particle counts showed large variations between the two techniques and although a correlation could be shown for ionic solutions no such correlation could be found for sugar containing solutions. Shape factors alone cannot explain these discrepancies but other differences fundamental to the physics of the two measuring techniques play an important part. We conclude that results obtained using one technique cannot be correlated, theoretically or actually, with those obtained from the other technique. PMID:6148396

  3. Particle size alterations of feedstuffs during in situ NDF incubation

    DEFF Research Database (Denmark)

    Krämer, Monika; Nørgaard, P.; Lund, Peter;

    2013-01-01

    Particle size alterations during neutral detergent fiber (NDF) determination and in situ rumen incubation were analyzed by dry sieving and image analysis. The in situ procedure for estimation of NDF degradation parameters and indigestible NDF concentration used for feed evaluation was thereby...... evaluated in terms of particle size for a broad range of feedstuffs which typically serve as NDF sources in dairy cow rations. Early and late cut grass silages, corn silage, alfalfa silage, rapeseed meal and dried distillers grains were examined. Treatments were I) drying and grinding of forage samples and...... determined and image analysis was used to estimate particle size profiles and thereby the risk for particle loss. Particle dimensions changed during NDF determination and in situ rumen incubation and variations depended on feedstuff and treatment. Late cut grass silage varied most in particle area among...

  4. Sonochemical synthesis of silica particles and their size control

    Science.gov (United States)

    Kim, Hwa-Min; Lee, Chang-Hyun; Kim, Bonghwan

    2016-09-01

    Using an ultrasound-assisted sol-gel method, we successfully synthesized very uniformly shaped, monodisperse, and size-controlled spherical silica particles from a mixture of ethanol, water, and tetraethyl orthosilicate in the presence of ammonia as catalyst, at room temperature. The diameters of the silica particles were distributed in the range from 40 to 400 nm; their morphology was well characterized by scanning electron microscopy. The silica particle size could be adjusted by choosing suitable concentrations of ammonium hydroxide and water, which in turn determined the nucleation and growth rates of the particles during the reaction. This sonochemical-based silica synthesis offers an alternative way to produce spherical silica particles in a relatively short reaction time. Thus, we suggest that this simple, low-cost, and efficient method of preparing uniform silica particles of various sizes will have practical and wide-ranging industrial applicability.

  5. The effect of airborne particles and weather conditions on pediatric respiratory infections in Cordoba, Argentine

    International Nuclear Information System (INIS)

    We studied the effect of estimated PM10 on respiratory infections in children from Cordoba, Argentine as well as the influence of weather factors, socio-economic conditions and education. We analyzed upper and lower respiratory infections and applied a time-series analysis with a quasi-Poisson distribution link function. To control for seasonally varying factors we fitted cubic smoothing splines of date. We also examined community-specific parameters and differences in susceptibility by sex. We found a significant association between particles and respiratory infections. This relationship was affected by mean temperature, atmospheric pressure and wind speed. These effects were stronger in fall, winter and spring for upper respiratory infections while for lower respiratory infections the association was significant only during spring. Low socio-economic conditions and low education levels increased the risk of respiratory infections. These findings add useful information to understand the influence of airborne particles on children health in developing countries. - Highlights: ► Few information is available on children respiratory health from developing countries. ► We modeled the association between PM10 and children's respiratory infections. ► We checked the influence of weather factors, socio-economic conditions, education and sex. ► Temperature, pressure and wind speed modified the effect of particles. ► Low socio-economic conditions and low education levels increased the risk of infections. - The concentration of airborne particles as well as low socio-economic conditions and low education levels are significant risk factors for upper and lower respiratory infections in children from Cordoba, Argentine.

  6. Determination of reactivity rates of silicate particle-size fractions

    Directory of Open Access Journals (Sweden)

    Angélica Cristina Fernandes Deus

    2014-04-01

    Full Text Available The efficiency of sources used for soil acidity correction depends on reactivity rate (RR and neutralization power (NP, indicated by effective calcium carbonate (ECC. Few studies establish relative efficiency of reactivity (RER for silicate particle-size fractions, therefore, the RER applied for lime are used. This study aimed to evaluate the reactivity of silicate materials affected by particle size throughout incubation periods in comparison to lime, and to calculate the RER for silicate particle-size fractions. Six correction sources were evaluated: three slags from distinct origins, dolomitic and calcitic lime separated into four particle-size fractions (2, 0.84, 0.30 and <0.30-mm sieves, and wollastonite, as an additional treatment. The treatments were applied to three soils with different texture classes. The dose of neutralizing material (calcium and magnesium oxides was applied at equal quantities, and the only variation was the particle-size material. After a 90-day incubation period, the RER was calculated for each particle-size fraction, as well as the RR and ECC of each source. The neutralization of soil acidity of the same particle-size fraction for different sources showed distinct solubility and a distinct reaction between silicates and lime. The RER for slag were higher than the limits established by Brazilian legislation, indicating that the method used for limes should not be used for the slags studied here.

  7. Particle size measurement from infrared laser ablation of tissue.

    Science.gov (United States)

    Cao, Fan; Donnarumma, Fabrizio; Murray, Kermit K

    2016-01-01

    The concentration and size distribution were measured for particles ablated from tissue sections using an infrared optical parametric oscillator laser system. A scanning mobility particle sizer and light scattering particle sizer were used in parallel to realize a particle sizing range from 10 nm to 20 μm. Tissue sections from rat brain and lung ranging in thickness between 10 and 50 μm were mounted on microscope slides and irradiated with nanosecond laser pulses at 3 μm wavelength and fluences between 7 and 21 kJ m(-2) in reflection geometry. The particle size distributions were characterized by a bimodal distribution with a large number of particles 100 nm in diameter and below and a large mass contribution from particles greater than 1 μm in diameter. The large particle contribution dominated the ablated particle mass at high laser fluence. The tissue type, thickness, and water content did not have a significant effect on the particle size distributions. The implications of these results for laser ablation sampling and mass spectrometry imaging under ambient conditions are discussed. PMID:26630332

  8. MONODISPERSE MICRON-SIZED POLYACRYLAMIDE PARTICLES SYNTHESIZED BY DISPERSION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Xin Hou; Bo Gao; Zhe-guo Zhang; Kang-de Yao

    2007-01-01

    Monodisperse micron-sized polyacrylamide (PAM) particles with a regular shape have been successfully prepared through dispersion polymerization of the monomer using a rotary reactor. FTIR and NMR spectroscopic results demonstrated the formation of PAM. POM and TEM observations revealed that PAM particles had a regular shape and good dispersity. A thick layer of surfactant (PVP) still existed on PAM particles after multiple centrifugation and ultrasonic re-dispersion in ethanol, which indicates a strong interaction between PVP and PAM. The effects of various polymerization factors on the average size of PAM particles have also been studied.

  9. Cytotoxicity evaluation of ceramic particles of different sizes and shapes.

    Science.gov (United States)

    Yamamoto, Akiko; Honma, Rieko; Sumita, Masae; Hanawa, Takao

    2004-02-01

    When artificial hip or knee joints are implanted in the human body, they release metallic, ceramic, and polymeric debris into the surrounding tissues. The toxicity of the released particles is of two types: chemical, caused by the released soluble ions and monomers, and mechanical, a result of mechanical stimulation produced by the insoluble particles. In this study, the cytotoxicity of particles of TiO2, Al2O3, ZrO2, Si3N4, and SiC for murine fibroblasts and macrophages were examined to evaluate just their mechanical toxicity because these particles are not expected to release soluble metal ions. Different sizes and shapes of TiO2 particles were used to evaluate the effect of size and shape on particle cytotoxicity. The results suggest that the cytotoxicity of ceramic particles does not depend on their chemical species. Cytotoxicity levels were lower than those of corresponding metal ions, indicating that the mechanical toxicity of particles is lower than the chemical toxicity of released soluble ions and monomers. The differences in size did not affect the mechanical toxicity of these particles. The dendritic particles had a higher cytotoxicity level for macrophages than did spindle and spheric particles. PMID:14704966

  10. Experimental study of particle size distribution in suspension polymerization

    International Nuclear Information System (INIS)

    Particle size distribution is an important characteristic in suspension polymerization. Special condition must satisfy for achievement of an appropriate particle size distribution This condition is studied for some systems. In this work the effect of parameters affecting the suspension polymerization system of styrene was studied and then the approximate optimum range was determined to obtain narrow particle size distribution mainly in the range of 200 to 400 microns. The studied parameters are: position of impeller, impeller type, impeller speed, baffles, stabilizer concentration, initiator concentration and divinylbenzene concentration as cross-linking agent

  11. Treatment of airborne asbestos and asbestos-like microfiber particles using atmospheric microwave air plasma

    International Nuclear Information System (INIS)

    Highlights: → We use atmospheric microwave air plasma to treat ceramic fiber and stainless fiber as asbestos alike micro fiber particle. → Spheroidization of certain type of ceramic fiber and stainless fiber particle. → The evaluation of the treated particles by the fiber vanishing rate. → Good fiber vanishing rate is observed for fiber particle with diameter below 10 μm. → The treatment of pure asbestos and a suggestion of the use of this method for the treatment airborne asbestos. - Abstract: Atmospheric microwave air plasma was used to treat asbestos-like microfiber particles that had two types of ceramic fiber and one type of stainless fiber. The treated particles were characterized via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The experiment results showed that one type of ceramic fiber (Alumina:Silica = 1:1) and the stainless fiber were spheroidized, but the other type of ceramic fiber (Alumina:Silica = 7:3) was not. The conversion of the fibers was investigated by calculating the equivalent diameter, the aspect ratio, and the fiber content ratio. The fiber content ratio in various conditions showed values near zero. The relationship between the normalized fiber vanishing rate and the energy needed to melt the particles completely per unit surface area of projected particles, which is defined as η, was examined and seen to indicate that the normalized fiber vanishing rate decreased rapidly with the increase in η. Finally, some preliminary experiments for pure asbestos were conducted, and the analysis via XRD and phase-contrast microscopy (PCM) showed the availability of the plasma treatment.

  12. Biofilter media gas pressure loss as related to media particle size and particle shape

    DEFF Research Database (Denmark)

    Pugliese, Lorenzo; Poulsen, Tjalfe G.; Røjgaard Andreasen, Rune

    2013-01-01

    Pressure loss (ΔP) is a key parameter for estimating biofilter energy consumption. Accurate predictions of ΔP as a function of air velocity (V) are therefore essential, to assess energy consumption and minimize operation costs. This paper investigates the combined impact of medium particle size and...... particle size fractions, with particle sizes ranging from 2 to 14 mm, were considered for each material. As expected, ΔP decreased with increasing particle size in agreement with earlier findings. ΔP, however, also showed a tendency to decrease with increasing particle roundness especially for fractions...... containing smaller particles. A new model concept for estimating V - ΔP across different particle size fractions and shapes was proposed. This model yielded improved prediction accuracy in comparison with existing prediction approaches....

  13. CALCULATION OF PARTICLE SIZE OF TITANIUM DIOXIDE HYDROSOL

    Directory of Open Access Journals (Sweden)

    L. M. Sliapniova

    2014-01-01

    Full Text Available One of the problems facing chemists who are involved in obtaining disperse systems with micro- and nanoscale particles of the disperse phase is a size evaluation of the obtained particles. Formation of hydrated sol is one of the stages for obtaining nanopowders while using sol-gel-method. We have obtained titanium dioxide hydrosol while using titanium tetrachloride hydrolysis in the presence of organic solvent with the purpose to get titanium dioxide powder It has been necessary to evaluate size of titanium dioxide hydrosol particles because particle dimensions of disperse hydrosol phase are directly interrelated with the obtained powder dispersiveness.Size calculation of titanium dioxide hydrosol particles of disperse phase has been executed in accordance with the Rayleigh equation and it has been shown that calculation results correspond to experimental data of atomic force microscopy and X-ray crystal analysis of the powder obtained from hydrosol.In order to calculate particle size in the disperse system it is possible to use the Rayleigh equation if the particle size is not more than 1/10 of wave length of impinging light or the Heller equation for the system including particles with diameter less than wave length of the impinging light but which is more than 1/10 of its value. Titaniun dioxide hydrosol has been obtained and an index of the wave ration has been calculated in the Heller equation. The obtained value has testified about high dispersiveness of the system and possibility to use the Rayleigh equation for calculation of the particle size in the disperse phase. Calculation of disperse-phase particle size of titanium dioxide hydrosol has corresponded to experimental data of the atomic force microscopy and X-ray crystal analysis for the powder obtained from the system.

  14. Particle size distributions in the Eastern Mediterranean troposphere

    Science.gov (United States)

    Kalivitis, N.; Birmili, W.; Stock, M.; Wehner, B.; Massling, A.; Wiedensohler, A.; Gerasopoulos, E.; Mihalopoulos, N.

    2008-11-01

    Atmospheric particle size distributions were measured on Crete island, Greece in the Eastern Mediterranean during an intensive field campaign between 28 August and 20 October, 2005. Our instrumentation combined a differential mobility particle sizer (DMPS) and an aerodynamic particle sizer (APS) and measured number size distributions in the size range 0.018 μm 10 μm. Four time periods with distinct aerosol characteristics were discriminated, two corresponding to marine and polluted air masses, respectively. In marine air, the sub-μm size distributions showed two particle modes centered at 67 nm and 195 nm having total number concentrations between 900 and 2000 cm-3. In polluted air masses, the size distributions were mainly unimodal with a mode typically centered at 140 nm, with number concentrations varying between 1800 and 2900 cm-3. Super-μm particles showed number concentrations in the range from 0.01 to 2.5 cm-3 without any clear relation to air mass origin. A small number of short-lived particle nucleation events were recorded, where the calculated particle formation rates ranged between 1.1 1.7 cm-3 s-1. However, no particle nucleation and growth events comparable to those typical for the continental boundary layer were observed. Particles concentrations (Diameter <50 nm) were low compared to continental boundary layer conditions with an average concentration of 300 cm-3. The production of sulfuric acid and its subsequently condensation on preexisting particles was examined with the use of a simplistic box model. These calculations suggested that the day-time evolution of the Aitken particle population was governed mainly by coagulation and that particle formation was absent during most days.

  15. Particle size distribution in the tilapia Recirculating Aquaculture System

    OpenAIRE

    Stokic, Jelena

    2012-01-01

    This study was to evaluate methods for measuring and describing particle size distribution from three different spots in Tilapia recirculating system at University of Life Ccience in Ås, Norway. For this purpose serial filtration over different mesh size and parallel filtration over different mesh size methods were compared. Water samples were taken from before drum filter, after drum filter and after bio-filter (MBBR) and filtrated through eight different mesh size classes and calculated in ...

  16. Analysis of Particle Size Control in the Preparation of Nano-size CaCO3 Particles

    Institute of Scientific and Technical Information of China (English)

    曹维良; 王泽; 张敬畅

    2003-01-01

    Cubic shaped CaCO3 particles with mean size of 30-40nm were prepared by intermittent carbonation process without any additives. It was found that the flow rate of CO2 has no distinct influence on the particle size in the range of 30 120ml·min-1 under conditions of 13℃ and stirring rate of 680r·min-1. A further increase of flow rate makes the particles larger. When CO2 flow rate is 70ml·min-1, a high agitation rate is in favor of the reduction of the crystal size in the range of 70-680 r·min-1. When flow rate is 120 ml·min-1, the particles prepared at agitation rates of 680r·min-1 and 280r·min-1 have similar sizes, while products prepared at 90r·min-1 have larger size.

  17. Experimental analysis of particle sizes for PIV measurements

    Science.gov (United States)

    van Overbrüggen, Timo; Klaas, Michael; Soria, Julio; Schröder, Wolfgang

    2016-09-01

    The right choice of seeding particles strongly influences the outcome of a particle-image velocimetry (PIV) measurement. Particles have to scatter enough light to be seen by cameras and follow the flow faithfully. As the flow following behavior depends on the inertia and therefore the size of the particle, smaller particles are desirable. Unfortunately, larger particles possess better light scattering behavior, which is especially important for volumetric PIV measurements. In this paper, the particle response of two exemplary solid particles to an oscillatory air flow created by a piston movement is analyzed and compared to analytic results by Hjelmfelt and Mockros (1966 Appl. Sci. Res. 16 149–61) concerning phase lag and amplitude ratio between particle movement and flow field. To achieve realistic experimental boundary conditions, polydispersed particles are used for the analysis. The analytic results show a strong dependence on the diameter. That is, using the volumetric mean diameter an overestimation of the phase lag of the particles is determined, whereas an underestimation of phase lag is computed for the number mean diameter. Hence, for polydispersed particles a more general analysis than that based on the particle mean diameter is required to determine in detail the particle following behavior.

  18. Effect of Cobalt Particle Size on Acetone Steam Reforming

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junming; Zhang, He; Yu, Ning; Davidson, Stephen D.; Wang, Yong

    2015-06-11

    Carbon-supported cobalt nanoparticles with different particle sizes were synthesized and characterized by complementary characterization techniques such as X-ray diffraction, N-2 sorption, acetone temperature-programmed desorption, transmission electron microscopy, and CO chemisorption. Using acetone steam reforming reaction as a probe reaction, we revealed a volcano-shape curve of the intrinsic activity (turnover frequency of acetone) and the CO2 selectivity as a function of the cobalt particle size with the highest activity and selectivity observed at a particle size of approximately 12.8nm. Our results indicate that the overall performance of acetone steam reforming is related to a combination of particle-size-dependent acetone decomposition, water dissociation, and the oxidation state of the cobalt nanoparticles.

  19. Effect of synthesis conditions on particle size of HMS

    Institute of Scientific and Technical Information of China (English)

    LI Hao; LIU Hong; HE Shi-qiang

    2009-01-01

    HMS mesoporous molecular sieve was synthesized hydrothermally by using dodecylamine (DDA) as template and tetethylorthosilicalite (TEOS) as silicon source. The influence of the hydrothermal synthesis conditions on HMS particle size was studied systematically. The results showed that the smaller particle was obtained under the condition of DDA/SiO2=0.27, H2O/SiO2=66.7, EtOH/SiO2=6.5 mol and synthesis time of 18 h. The presences of additives (TW20, TW60, SP60 and Neopelex) also helped to the reduction of particle size. The HMS mesoporous molecular sieve with particle size around 60~100 nm was obtained by using TW20 or TW60 as an additive. In addition, TEM image showed that HMS mesoporous molecular sieve with pariticle size about 20~100 nm was synthesized in microemulsion.

  20. Noninvasive particle sizing using camera-based diffuse reflectance spectroscopy

    DEFF Research Database (Denmark)

    Abildgaard, Otto Højager Attermann; Frisvad, Jeppe Revall; Falster, Viggo;

    2016-01-01

    Diffuse reflectance measurements are useful for noninvasive inspection of optical properties such as reduced scattering and absorption coefficients. Spectroscopic analysis of these optical properties can be used for particle sizing. Systems based on optical fiber probes are commonly employed, but...... their low spatial resolution limits their validity ranges for the coefficients. To cover a wider range of coefficients, we use camera-based spectroscopic oblique incidence reflectometry. We develop a noninvasive technique for acquisition of apparent particle size distributions based on this approach....... Our technique is validated using stable oil-in-water emulsions with a wide range of known particle size distributions. We also measure the apparent particle size distributions of complex dairy products. These results show that our tool, in contrast to those based on fiber probes, can deal with a range...

  1. Chemical and isotopic properties and origin of coarse airborne particles collected by passive samplers in industrial, urban, and rural environments

    Science.gov (United States)

    Guéguen, Florence; Stille, Peter; Dietze, Volke; Gieré, Reto

    2012-12-01

    Passive air samplers have been installed in industrial, urban, rural and remote forested environments in order to collect coarse airborne particles for subsequent chemical characterization. To identify principal polluting sources, isotopic tracers, such as Sr, Nd and Pb isotopic ratios, have been used. The mass deposition rates (MDRs) of trace metals, determined for each of the studied environments, clearly indicate that industrial and traffic sites are especially affected by air pollution. Elements such as V, Pb, Fe, Cr, Co, Mo, Cd, Ni, As, Sb and Zn are notably enriched in samples from industrial zones, whereas V, Mn, Ba, Sr, Al, U, Th, rare earth elements (REE), Zr, Y, Cs, Rb, Sb, Sn and Cu are principal components of the airborne particles collected close to areas influenced by heavy traffic. The chemical/isotopic baseline composition derived from the airborne particles is the result of mixing of particles from different industrial sources, traffic and fertilizers. The monthly analysis of trace-metal MDRs of the collected airborne particle samples from different stations around the industrial zone allows for the detection of distinct atmospheric dust-deposition events during the year, characterized by high MDRs. "Natural" dusts from regional soil re-suspension, including from more distant regions like the Sahara desert, might overprint the regional atmospheric baseline composition, as suggested by trace metal trajectories in ternary diagrams and by Sr, Nd and Pb isotope data.

  2. Effects of impurities on particle sizing by acoustic attenuation spectroscopy

    OpenAIRE

    Inam, Muhammad Asif; Frances, Christine

    2010-01-01

    It is important to have correct information regarding particle size in order to interpret, control, and optimize many industrial processes. Prior to the recent advent of acoustic attenuation spectroscopy, it was difficult to study particle size distribution online and under real process conditions in processes involving concentrated dispersions (suspensions or emulsions). The technique still needs improvement because it is less known how and under which conditions to employ the technique when...

  3. Fabrication and characterization of thermally actuated micromechanical resonators for airborne particle mass sensing: II. Device fabrication and characterization

    International Nuclear Information System (INIS)

    This paper, the second of two parts, presents extensive measurement and characterization results on fabricated thermally actuated single-crystal silicon MEMS resonators analyzed in part I. The resonators have been fabricated using a single mask process on SOI substrates. Resonant frequencies in a few hundreds of kHz to a few MHz and equivalent motional conductances as high as 102 mA V−1 have been measured for the fabricated resonators. The measurement results have been compared to the resonator characteristics predicted by the model developed in part I showing a good agreement between the two. Despite the relatively low frequencies, high quality factors (Q) of the order of a few thousand have been measured for the resonators under atmospheric pressure. The mass sensitivities of some of the resonators were characterized by embedding them in a custom-made test setup and deposition of artificially generated aerosol particles with known size and composition. The resulting measured mass sensitivities are of the order of tens to hundreds of Hz ng−1 and are in agreement with the expected values based on the resonator's physical dimensions. Finally, measurement of mass density of arbitrary airborne particles in the surrounding lab environment has been demonstrated

  4. A system for aerodynamically sizing ultrafine environmental radioactive particles

    International Nuclear Information System (INIS)

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

  5. A system for aerodynamically sizing ultrafine environmental radioactive particles

    Energy Technology Data Exchange (ETDEWEB)

    Olawoyin, L.

    1995-09-01

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

  6. Particle-size dependence on metal(loid) distributions in mine wastes: Implications for water contamination and human exposure

    Science.gov (United States)

    Kim, C.S.; Wilson, K.M.; Rytuba, J.J.

    2011-01-01

    The mining and processing of metal-bearing ores has resulted in contamination issues where waste materials from abandoned mines remain in piles of untreated and unconsolidated material, posing the potential for waterborne and airborne transport of toxic elements. This study presents a systematic method of particle size separation, mass distribution, and bulk chemical analysis for mine tailings and adjacent background soil samples from the Rand historic mining district, California, in order to assess particle size distribution and related trends in metal(loid) concentration as a function of particle size. Mine tailings produced through stamp milling and leaching processes were found to have both a narrower and finer particle size distribution than background samples, with significant fractions of particles available in a size range (???250 ??m) that could be incidentally ingested. In both tailings and background samples, the majority of trace metal(loid)s display an inverse relationship between concentration and particle size, resulting in higher proportions of As, Cr, Cu, Pb and Zn in finer-sized fractions which are more susceptible to both water- and wind-borne transport as well as ingestion and/or inhalation. Established regulatory screening levels for such elements may, therefore, significantly underestimate potential exposure risk if relying solely on bulk sample concentrations to guide remediation decisions. Correlations in elemental concentration trends (such as between As and Fe) indicate relationships between elements that may be relevant to their chemical speciation. ?? 2011 Elsevier Ltd.

  7. FRACTIONATION OF PULP AND PAPER PARTICLES SELECTIVELY BY SIZE

    Directory of Open Access Journals (Sweden)

    Ossi Tapio Laitinen

    2011-02-01

    Full Text Available A study was made of the classification of pulp, paper, and peat particles by size with a device called a tube flow fractionator. An accurate and simple experimental model was formulated in order to estimate the time required for fractionation, yielding an excellent correlation between the observed and predicted fractionation times. The results showed that the fractionation time of a certain size of pulp, paper, and peat particles in the tube flow device can be accurately estimated from the length, width, and thickness of the particle. The results can be used to facilitate the selection of specific fractions of pulp and paper samples.

  8. Finite size effect of harmonic measure estimation in a DLA model: Variable size of probe particles

    Science.gov (United States)

    Menshutin, Anton Yu.; Shchur, Lev N.; Vinokour, Valery M.

    2008-11-01

    A finite size effect in the probing of the harmonic measure in simulation of diffusion-limited aggregation (DLA) growth is investigated. We introduce a variable size of probe particles, to estimate harmonic measure and extract the fractal dimension of DLA clusters taking two limits, of vanishingly small probe particle size and of infinitely large size of a DLA cluster. We generate 1000 DLA clusters consisting of 50 million particles each, using an off-lattice killing-free algorithm developed in the early work. The introduced method leads to unprecedented accuracy in the estimation of the fractal dimension. We discuss the variation of the probability distribution function with the size of probing particles.

  9. The variation of solubility of strontium sulphate with particle size

    International Nuclear Information System (INIS)

    Radioactive sulphur was used to study the variation of solubility of strontium sulphate with particle size. Synthetic methods were used to control the particle size (d = 160-1000 A) and the size distribution was determined by electron microscopy. The separation of phases was carried out by sedimentation and the supernatant liquid was examined with the electron microscope to check for existence of peptized particles. The concentration of the dissolved SrSO4 was determined by evaporation of an aliquot of the supernatant and determining the sulphur activity. The results were found to follow the Ostwald-Freundlich equation for solubility with the smallest particles in a given distribution determining the solubility. From the solubility data an interfacial tension of 84±8 erg/cm2 was obtained, a value much lower than previously reported in the literature. The Ostwald-Freundlich equation was extended to crystals of any geometry. Using this extended equation the interfacial tension of tho different faces of strontium sulphate was calculated. The data on variation of solubility with particle size and on the synthesis of particles of SrSO4 were used to determine the size of the nucleus of SrSO4. Semiquantitative observations showed that the rate of solubility is much faster than the rate of growth. (author)

  10. Assessment of oxidative DNA damage formation by organic complex mixtures from airborne particles PM10

    International Nuclear Information System (INIS)

    The free radical generating activity of airborne particulate matter (PM10) has been proposed as a primary mechanism in biological activity of ambient air pollution. In an effort to determine the impact of the complex mixtures of extractable organic matter (EOM) from airborne particles on oxidative damage to DNA, the level of 8-oxo-2'-deoxyguanosine (8-oxodG), the most prevalent and stable oxidative lesion, was measured in the human metabolically competent cell line Hep G2. Cultured cells were exposed to equivalent EOM concentrations (5-150 μg/ml) and oxidative DNA damage was analyzed using a modified single cell gel electrophoresis (SCGE), which involves the incubation of whole cell DNA with repair specific DNA endonuclease, which cleaves oxidized DNA at the sites of 8-oxodG. EOMs were extracted from PM10 collected daily (24 h intervals) in three European cities: Prague (Czech Republic, two monitoring sites, Libus and Smichov), Kosice (Slovak Republic) and Sofia (Bulgaria) during 3-month sampling periods in the winter and summer seasons. No substantial time- and dose-dependent increase of oxidative DNA lesions was detected in EOM-treated cells with the exception of the EOM collected at the monitoring site Kosice, summer sampling. In this case, 2 h cell exposure to EOM resulted in a slight but significant increase of oxidative DNA damage at three from total of six concentrations. The mean 8-oxodG values at these concentrations ranged from 15.3 to 26.1 per 106 nucleotides with a value 3.5 per 106 nucleotides in untreated cells. B[a]P, the positive control, induced a variable but insignificant increase of oxidative DNA damage in Hep G2 cell (approximately 1.6-fold increase over control value). Based on these data we believe that EOM samples extracted from airborne particle PM10 play probably only a marginal role in oxidative stress generation and oxidative lesion formation to DNA. However, adsorbed organic compounds can undergo various interactions (additive or

  11. Assessment of oxidative DNA damage formation by organic complex mixtures from airborne particles PM(10).

    Science.gov (United States)

    Gábelová, Alena; Valovicová, Zuzana; Lábaj, Juraj; Bacová, Gabriela; Binková, Blanka; Farmer, Peter B

    2007-07-01

    The free radical generating activity of airborne particulate matter (PM(10)) has been proposed as a primary mechanism in biological activity of ambient air pollution. In an effort to determine the impact of the complex mixtures of extractable organic matter (EOM) from airborne particles on oxidative damage to DNA, the level of 8-oxo-2'-deoxyguanosine (8-oxodG), the most prevalent and stable oxidative lesion, was measured in the human metabolically competent cell line Hep G2. Cultured cells were exposed to equivalent EOM concentrations (5-150microg/ml) and oxidative DNA damage was analyzed using a modified single cell gel electrophoresis (SCGE), which involves the incubation of whole cell DNA with repair specific DNA endonuclease, which cleaves oxidized DNA at the sites of 8-oxodG. EOMs were extracted from PM(10) collected daily (24h intervals) in three European cities: Prague (Czech Republic, two monitoring sites, Libus and Smíchov), Kosice (Slovak Republic) and Sofia (Bulgaria) during 3-month sampling periods in the winter and summer seasons. No substantial time- and dose-dependent increase of oxidative DNA lesions was detected in EOM-treated cells with the exception of the EOM collected at the monitoring site Kosice, summer sampling. In this case, 2h cell exposure to EOM resulted in a slight but significant increase of oxidative DNA damage at three from total of six concentrations. The mean 8-oxodG values at these concentrations ranged from 15.3 to 26.1 per 10(6) nucleotides with a value 3.5 per 10(6) nucleotides in untreated cells. B[a]P, the positive control, induced a variable but insignificant increase of oxidative DNA damage in Hep G2 cell (approximately 1.6-fold increase over control value). Based on these data we believe that EOM samples extracted from airborne particle PM(10) play probably only a marginal role in oxidative stress generation and oxidative lesion formation to DNA. However, adsorbed organic compounds can undergo various interactions

  12. Prediction of Particle Size of Ammonium Perchlorate during Pulverisation

    Directory of Open Access Journals (Sweden)

    Sunil Jain

    2006-07-01

    Full Text Available Ammonium perchlorate has been pulverised by an impact mill (air classifier mill to studythe influence of different operating parameters, viz., effect of mill speed, classifier speed, feedrate, and damper opening (suction rate on the particle size. Further based on the differentgrinding parameters, an empirical equation has been developed and used for the prediction ofparticle size. The experimental results indicate that the values are very close to the predictedones. In addition, particle size distribution has also been studied by applying different modelequations and it has been found that Rosin-Rammler model is the most suitable model for thisoperation.

  13. Measurement of particle size based on digital imaging technique

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong; TANG Hong-wu; LIU Yun; WANG Hao; LIU Gui-ping

    2013-01-01

    To improve the analysis methods for the measurement of the sediment particle sizes with a wide distribution and of irregular shapes,a sediment particle image measurement,an analysis system,and an extraction algorithm of the optimal threshold based on the gray histogram peak values are proposed.Recording the pixels of the sediment particles by labeling them,the algorithm can effectively separate the sediment particle images from the background images using the equivalent pixel circles with the same diameters to represent the sediment particles.Compared with the laser analyzer for the case of blue plastic sands,the measurement results of the system are shown to be reasonably similar.The errors are mainly due to the small size of the particles and the limitation of the apparatus.The measurement accuracy can be improved by increasing the Charge-Coupled Devices (CCD) camera resolution.The analysis method of the sediment particle images can provide a technical support for the rapid measurement of the sediment particle size and its distribution.

  14. On the interaction between glyceraldehyde-3-phosphate dehydrogenase and airborne particles: Evidence for electrophilic species

    Science.gov (United States)

    Shinyashiki, Masaru; Rodriguez, Chester E.; Di Stefano, Emma W.; Sioutas, Constantinos; Delfino, Ralph J.; Kumagai, Yoshito; Froines, John R.; Cho, Arthur K.

    Many of the adverse health effects of airborne particulate matter (PM) have been attributed to the chemical properties of some of the large number of chemical species present in PM. Some PM component chemicals are capable of generating reactive oxygen species and eliciting a state of oxidative stress. In addition, however, PM can contain chemical species that elicit their effects through covalent bond formation with nucleophilic functions in the cell. In this manuscript, we report the presence of constituents with electrophilic properties in ambient and diesel exhaust particles, demonstrated by their ability to inhibit the thiol enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GAPDH is irreversibly inactivated by electrophiles under anaerobic conditions by covalent bond formation. This inactivation can be blocked by the prior addition of a high concentration of dithiothreitol (DTT) as an alternate nucleophile. Addition of DTT after the reaction between the electrophile and GAPDH, however, does not reverse the inactivation. This property has been utilized to develop a procedure that provides a quantitative measure of electrophiles present in samples of ambient particles collected in the Los Angeles Basin and in diesel exhaust particles. The toxicity of electrophiles is the result of irreversible changes in biological molecules; recovery is dependent on resynthesis. If the resynthesis is slow, the irreversible effects can be cumulative and manifest themselves after chronic exposure to low levels of electrophiles.

  15. Alternate particle removal technologies for the Airborne Activity Confinement System at the Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Brockmann, J.E.; Adkins, C.L.J.; Gelbard, F. [Sandia National Labs., Albuquerque, NM (United States)

    1991-09-01

    This report presents a review of the filtration technologies available for the removal of particulate material from a gas stream. It was undertaken to identify alternate filtration technologies that may be employed in the Airborne Activity Confinement System (AACS) at the Savannah River Plant. This report is organized into six sections: (1) a discussion of the aerosol source term and its definition, (2) a short discussion of particle and gaseous contaminant removal mechanisms, (3) a brief overview of particle removal technologies, (4) a discussion of the existing AACS and its potential shortcomings, (5) an enumeration of issues to be addressed in upgrading the AACS, and, (6) a detailed discussion of the identified technologies. The purpose of this report is to identity available options to the existing particle removal system. This system is in continuous operation during routine operation of the reactor. As will be seen, there are a number of options and the selection of any technology or combination of technologies will depend on the design aerosol source term (yet to be appropriately defined) as well as the flow requirements and configuration. This report does not select a specific technology. It focuses on particulate removal and qualitatively on the removal of radio-iodine and mist elimination. Candidate technologies have been selected from industrial and nuclear gas cleaning applications.

  16. Alternate particle removal technologies for the Airborne Activity Confinement System at the Savannah River Site

    International Nuclear Information System (INIS)

    This report presents a review of the filtration technologies available for the removal of particulate material from a gas stream. It was undertaken to identify alternate filtration technologies that may be employed in the Airborne Activity Confinement System (AACS) at the Savannah River Plant. This report is organized into six sections: (1) a discussion of the aerosol source term and its definition, (2) a short discussion of particle and gaseous contaminant removal mechanisms, (3) a brief overview of particle removal technologies, (4) a discussion of the existing AACS and its potential shortcomings, (5) an enumeration of issues to be addressed in upgrading the AACS, and, (6) a detailed discussion of the identified technologies. The purpose of this report is to identity available options to the existing particle removal system. This system is in continuous operation during routine operation of the reactor. As will be seen, there are a number of options and the selection of any technology or combination of technologies will depend on the design aerosol source term (yet to be appropriately defined) as well as the flow requirements and configuration. This report does not select a specific technology. It focuses on particulate removal and qualitatively on the removal of radio-iodine and mist elimination. Candidate technologies have been selected from industrial and nuclear gas cleaning applications

  17. Size distribution of particle systems analyzed with organic photodetectors

    CERN Document Server

    Sentis, Matthias

    2015-01-01

    As part of a consortium between academic and industry, this PhD work investigates the interest and capabilities of organic photo-sensors (OPS) for the optical characterization of suspensions and two-phase flows. The principle of new optical particle sizing instruments is proposed to characterize particle systems confined in a cylinder glass (standard configuration for Process Analytical Technologies). To evaluate and optimize the performance of these systems, a Monte-Carlo model has been specifically developed. This model accounts for the numerous parameters of the system: laser beam profile, mirrors, lenses, sample cell, particle medium properties (concentration, mean & standard deviation, refractive indices), OPS shape and positions, etc. Light scattering by particles is treated either by using Lorenz-Mie theory, Debye, or a hybrid model (that takes into account the geometrical and physical contributions). For diluted media (single scattering), particle size analysis is based on the inversion of scatter...

  18. Size distribution of natural aerosols and radioactive particles issued from radon, in marine and hardly polluted urban atmospheres

    International Nuclear Information System (INIS)

    With a view to studying the natural radioactive particles produced by atttachment of 222Rn daughters on environmental aerosol particles, the behaviours of CASELLA MK2 and ANDERSEN cascade impactors were first investigated. Their characteristic stage diameters were determined and size distributions of airborne particles were obtained in various situations. Moreover, an experimental and automatic equipment for measuring radon was devised and a method was developed in order to evaluate RaA, RaB, RaC concentrations in the free atmosphere. A degree of radioactive desequilibrium between 222Rn and its daughters, more important than that in other locations was thus demonstrated. Furthermore, by means of various aerosol collection systems (ion tubes, diffusion batteries, cascade impactors, filters), the cumulative size distribution of natural radioactivity was established in the air, at ground level. Finally, from a theory of attachment of small radioactive ions on atmospheric particles, a tentative explanation of experimental results was made

  19. RNA Control of HIV-1 Particle Size Polydispersity

    CERN Document Server

    Faivre-Moskalenko, Cendrine; Thomas, Audrey; Tartour, Kevin; Beck, Yvonne; Iazykov, Maksym; Danial, John; Lourdin, Morgane; Muriaux, Delphine; Castelnovo, Martin

    2014-01-01

    HIV-1, an enveloped RNA virus, produces viral particles that are known to be much more heterogeneous in size than is typical of non-enveloped viruses. We present here a novel strategy to study HIV-1 Viral Like Particles (VLP) assembly by measuring the size distribution of these purified VLPs and subsequent viral cores thanks to Atomic Force Microscopy imaging and statistical analysis. This strategy allowed us to identify whether the presence of viral RNA acts as a modulator for VLPs and cores size heterogeneity in a large population of particles. These results are analyzed in the light of a recently proposed statistical physics model for the self-assembly process. In particular, our results reveal that the modulation of size distribution by the presence of viral RNA is qualitatively reproduced, suggesting therefore an entropic origin for the modulation of RNA uptake by the nascent VLP.

  20. An overview of differential mobility analyzers for size classification of nanometer-sized aerosol particles

    Directory of Open Access Journals (Sweden)

    Nakorn Tippayawong

    2008-03-01

    Full Text Available Size classification of nanoparticles is an important process in the electrical mobility particle size analyzer. The differential mobility analyzer (DMA is one of the most commonly used devices for classifying and measuring nanometersized aerosol particles between 1 nm to 1 μm in diameter, based on their electrical mobility. The DMA can be described as an assembly of two concentrically cylindrical electrodes with an air gap between the walls. In the DMA, air and aerosol flows enter from one end, pass through the annulus and exit the other end. An electric field is applied between the inner and outer electrodes. Particles having a specific mobility exit with the monodisperse air flow through a small slit located at the bottom of the inner electrode. These particles are transferred to a particle counter to determine the particle number concentration. In the past several decades, there have been numerous extensive studies and developments on the DMA. Nonetheless, they are different in terms of specific applications, construction, particle size range, as well as time response and resolution. The purpose of this article is to provide an overview of the state-of-the-art existing cylindrical DMAs for aerosol particle size classification as well as for the generation of monodisperse aerosol in nanometer size range. A description of the operating principles, detailed physical characteristics of these DMAs, including the single-channel and multi-channel DMAs, as well as some examples of applications to nanotechnology are given.

  1. Influences of Substrate Adhesion and Particle Size on the Shape Memory Effect of Polystyrene Particles.

    Science.gov (United States)

    Cox, Lewis M; Killgore, Jason P; Li, Zhengwei; Long, Rong; Sanders, Aric W; Xiao, Jianliang; Ding, Yifu

    2016-04-19

    Formulations and applications of micro- and nanoscale polymer particles have proliferated rapidly in recent years, yet knowledge of their mechanical behavior has not grown accordingly. In this study, we examine the ways that compressive strain, substrate surface energy, and particle size influence the shape memory cycle of polystyrene particles. Using nanoimprint lithography, differently sized particles are programmed into highly deformed, temporary shapes in contact with substrates of differing surface energies. Atomic force microscopy is used to obtain in situ measurements of particle shape recovery kinetics, and scanning electron microscopy is employed to assess differences in the profiles of particles at the conclusion of the shape memory cycle. Finally, finite element models are used to investigate the growing impact of surface energies at smaller length scales. Results reveal that the influence of substrate adhesion on particle recovery is size-dependent and can become dominating at submicron length scales. PMID:27023181

  2. Retrieval of particle size distribution from aerosol optical thickness using an improved particle swarm optimization algorithm

    Science.gov (United States)

    Mao, Jiandong; Li, Jinxuan

    2015-10-01

    Particle size distribution is essential for describing direct and indirect radiation of aerosols. Because the relationship between the aerosol size distribution and optical thickness (AOT) is an ill-posed Fredholm integral equation of the first type, the traditional techniques for determining such size distributions, such as the Phillips-Twomey regularization method, are often ambiguous. Here, we use an approach based on an improved particle swarm optimization algorithm (IPSO) to retrieve aerosol size distribution. Using AOT data measured by a CE318 sun photometer in Yinchuan, we compared the aerosol size distributions retrieved using a simple genetic algorithm, a basic particle swarm optimization algorithm and the IPSO. Aerosol size distributions for different weather conditions were analyzed, including sunny, dusty and hazy conditions. Our results show that the IPSO-based inversion method retrieved aerosol size distributions under all weather conditions, showing great potential for similar size distribution inversions.

  3. Effect of indoor-generated airborne particles on radon progeny dynamics.

    Science.gov (United States)

    Trassierra, C Vargas; Stabile, L; Cardellini, F; Morawska, L; Buonanno, G

    2016-08-15

    In order to investigate the interaction between radon progeny and particles, an experimental campaign was carried out in a radon chamber at the Italian National Institute of Ionizing Radiation Metrology, quantifying the amount of attached and unattached radon daughters present in air, as well as the equilibrium factor in the presence of particles generated through indoor sources. A fixed radon concentration was maintained, while particles were generated using incense sticks, mosquito coils and gas combustion. Aerosols were characterized in terms of particle concentrations and size distributions. Simultaneously, radon concentration and attached/unattached potential alpha energy concentration in the air were continuously monitored by two different devices, based on alpha spectroscopy techniques. The presence of particles was found to affect the attached fraction of radon decay products, in such a way that the particles acted as a sink for radionuclides. In terms of sources which emit large particles (e.g. incense, mosquito coils), which greatly increase particle surface area concentrations, the Equilibrium Factor was found to double with respect to the background level before particle generation sessions. On the contrary, the radon decay product dynamics were not influenced by gas combustion processes, mainly due to the small surface area of the particles emitted. PMID:27131455

  4. Studies on the particle size control of gelatin microspheres

    Institute of Scientific and Technical Information of China (English)

    Ruixue SUN; Jingjing SHI; Yanchuan GUO; Lijuan CHEN

    2009-01-01

    A series of gelatin microspheres (GMs) were prepared through emulsification-coacervation method in water-in-oil (w/o) emulsions. The influence of preparation parameters on particle size, surface morphology, and dispersion of GMs was examined. The studied preparation parameters include concentration of gelatin solutions, concentration of the emulsifier, w/o ratio, emulsifying time, stirring speed, and so on. The surface morphology, dispersion, and particle sizes of GMs were determined by the scanning electron microscopy (SEM), SemAfore 4 Demo software, and particle size distribution graphic charts. The experimental results indicated that increasing the concentration of gelatin solution would increase the particle size of GMs. When the solution concentration increased from 0.050 to 0.200 g/mL gradually, the particle size increased correspondingly. The relationship between the two quantities was linear. On the contrary, increasing the concentration of the emulsifier would decrease the particle size of GMs. Furthermore, the particle size reduced quickly at initial time and slowed down latterly. With the increase of emulsifier concentration from 0 to 0.020 g/mL, the mean diameters of GMs decreased from 17.32 to 5.38 urn. However, the particle size dwindled slowly when emulsifier concentration was higher than 0.020 g/mL. The excellent result was obtained with the condition of 0.050 g/mL of emulsifier concentration, 0.100 g/mL of gelatin solution concentration, 1/5 of w/o ratio, 10 min of emulsifying time, and 900 r/min of the stirring speed. The GMs prepared at this condition had the smallest sizes, the narrowest size distribution, the best spherical shape, and fluidity. The w/o ratio has the same influence on particle size of GMs as that of gelatin solution concentration. With the increase of w/o ratio, the average particle sizes increased linearly, and the surface of microspheres become smoother as well. It is supposed that w/o ratio can be used to change the diameters

  5. Ionization cluster size distribution for alpha particles: Experiment, modelling

    International Nuclear Information System (INIS)

    The paper presents data for measured ionization cluster size distributions by alpha particles in tissue equivalent media and comparison with the simulated data for liquid water. The experiments were carried out with a beam of 4.6 MeV alpha particles performed in a setup called the JET Counter. The theoretically derived cluster size distributions for alphas particles were obtained using the K-means algorithm. The simulation was carried out by Monte Carlo track structure calculations using cross sections for liquid water. The first moments of cluster size distributions, derived from K-means algorithm as a function of diameter of cluster centroid, were compared with the corresponding moments derived from the experiments for nitrogen and propane targets. It was found that the ratio of the first moments for water to gas targets correlates well with the corresponding ratio of the mean free paths for primary ionization by alpha particles in the two media. It is shown that the cluster size distributions for alpha particles in water, obtained from K-means algorithm, are in agreement with the corresponding distributions measured experimentally in nitrogen or propane gas targets of nano-meter sizes. (authors)

  6. Direct Deposition of Gas Phase Generated Aerosol Gold Nanoparticles into Biological Fluids - Corona Formation and Particle Size Shifts

    Science.gov (United States)

    Svensson, Christian R.; Messing, Maria E.; Lundqvist, Martin; Schollin, Alexander; Deppert, Knut; Pagels, Joakim H.; Rissler, Jenny; Cedervall, Tommy

    2013-01-01

    An ongoing discussion whether traditional toxicological methods are sufficient to evaluate the risks associated with nanoparticle inhalation has led to the emergence of Air-Liquid interface toxicology. As a step in this process, this study explores the evolution of particle characteristics as they move from the airborne state into physiological solution. Airborne gold nanoparticles (AuNP) are generated using an evaporation-condensation technique. Spherical and agglomerate AuNPs are deposited into physiological solutions of increasing biological complexity. The AuNP size is characterized in air as mobility diameter and in liquid as hydrodynamic diameter. AuNP:Protein aggregation in physiological solutions is determined using dynamic light scattering, particle tracking analysis, and UV absorption spectroscopy. AuNPs deposited into homocysteine buffer form large gold-aggregates. Spherical AuNPs deposited in solutions of albumin were trapped at the Air-Liquid interface but was readily suspended in the solutions with a size close to that of the airborne particles, indicating that AuNP:Protein complex formation is promoted. Deposition into serum and lung fluid resulted in larger complexes, reflecting the formation of a more complex protein corona. UV absorption spectroscopy indicated no further aggregation of the AuNPs after deposition in solution. The corona of the deposited AuNPs shows differences compared to AuNPs generated in suspension. Deposition of AuNPs from the aerosol phase into biological fluids offers a method to study the protein corona formed, upon inhalation and deposition in the lungs in a more realistic way compared to particle liquid suspensions. This is important since the protein corona together with key particle properties (e.g. size, shape and surface reactivity) to a large extent may determine the nanoparticle effects and possible translocation to other organs. PMID:24086363

  7. Seasonal size distribution of airborne culturable bacteria and fungi and preliminary estimation of their deposition in human lungs during non-haze and haze days

    Science.gov (United States)

    Gao, Min; Jia, Ruizhi; Qiu, Tianlei; Han, Meilin; Song, Yuan; Wang, Xuming

    2015-10-01

    In recent years, haze events in Beijing have significantly increased in frequency. On haze days, airborne microorganisms are considered to be a potential risk factor for various health concerns. However, limited information on bioaerosols has prevented our proper understanding of the possible threat to human health due to these bioaerosols. In this study, we used a six-stage impactor for sampling culturable bioaerosols and the LUDEP 2.07 computer-based model for calculating their deposition on human lungs to investigate seasonal concentration, size distribution, and corresponding deposition efficiency and flux in the human respiratory tract during different haze-level events. The current results of the analysis of 398 samples over four seasons indicate that the concentration of culturable airborne bacteria decreased with increasing haze severity. The bioaerosol concentration ratio was skewed towards larger particle sizes on heavy haze days leading to larger bioaerosol aerodynamic diameters than on non-haze days. During nasal breathing by an adult male engaged in light exercise in an outdoor environment, the total deposition efficiency of culturable bioaerosols is 80-90% including approximately 70% in the upper respiratory tract, 5-7% in the alveoli, and about 3% in the bronchial couple with bronchiolar regions. Although the difference in culturable bioaerosol aerodynamic diameters at different haze levels was not large enough to cause obvious differences in lung deposition efficiency, the deposition fluxes clearly varied with the degree of haze owing to the varied concentration of culturable airborne bacteria and fungi. The results here could improve our understanding of the seasonal health threat due to culturable bioaerosols during non-haze and haze days.

  8. Spontaneous formation of small sized albumin/acacia coacervate particles.

    Science.gov (United States)

    Burgess, D J; Singh, O N

    1993-07-01

    Microgel coacervate particles form spontaneously on mixing aqueous solutions of oppositely charged albumin and acacia, under specific conditions of pH, ionic strength, and polyion concentration, close to but not at the optimum conditions for maximum coacervate yield. The mean particle diameter of these coacervate particles is approximately 6 microns when suspended in aqueous media, as determined by HIAC/Royco particle analysis. The geometric standard deviation of the particles falls in the range 1.2-1.9 microns. The particle size was not dependent on the method of emulsification of the coacervate in the equilibrium phase, or on the stirring speed applied during the manufacturing process. The microgel particles were stable on storage, for periods up to forty-six days, without the addition of a chemical cross-linking agent, or the application of heat. Stability was measured with respect to the change in particle size of samples stored at different temperatures. The non-cross-linked microcapsules were also shown to be stable on pH change, to pH values outside the coacervation pH range. At the optimum conditions for maximum coacervate yield the albumin/acacia system formed a very viscous coacervate phase, which was unsuitable for microcapsule preparation. The rheological properties of albumin/acacia and gelatin/acacia complex coacervates optimized for maximum coacervate yield were compared. The albumin/acacia coacervate was shown to be three orders of magnitude more viscous than the gelatin/acacia system. PMID:8105049

  9. Particle size studies in the preparation of AQCS reference materials

    International Nuclear Information System (INIS)

    Particle size determination is one of the important steps in the characterization of physical properties of each particulate material. However, particle size distribution effects also a chemical composition of the material in terms of homogeneity and representativeness of the sample, as well as allows or not a possible sub-sampling of the material. All this is of great importance in the preparation of reference materials for which the chemical composition and physical properties have to be extremely well characterized. In the present paper we intend to present same efforts which have been done by Analytical Quality Control Services (AQCS) of the International Atomic Energy Agency (IAEA) in the field of particle size determination in the production of reference materials. The Malvern product MasterSizer X, based on laser light scattering is used for this purpose and the technique is also shortly discussed. (author)

  10. Dust Particle Size Distributions during Spring in Yinchuan, China

    OpenAIRE

    Jiangfeng Shao; Jiandong Mao

    2016-01-01

    Dust particle size distributions in Yinchuan, China, were measured during March and April 2014, using APS-3321 sampler. The distributions were measured under different dust conditions (background, floating dust, blowing dust, and dust storm) and statistical analyses were performed. The results showed that, under different dust conditions, the instantaneous number concentrations of dust particles differed widely. For example, during blowing sand and dust storm conditions, instantaneous dust pa...

  11. Size distribution of particle systems analyzed with organic photodetectors

    OpenAIRE

    Sentis, Matthias

    2015-01-01

    As part of a consortium between academic and industry, this PhD work investigates the interest and capabilities of organic photo-sensors (OPS) for the optical characterization of suspensions and two-phase flows. The principle of new optical particle sizing instruments is proposed to characterize particle systems confined in a cylinder glass (standard configuration for Process Analytical Technologies). To evaluate and optimize the performance of these systems, a Monte-Carlo model has been spec...

  12. Advanced analysis of polymer emulsions: Particle size and particle size distribution by field-flow fractionation and dynamic light scattering.

    Science.gov (United States)

    Makan, Ashwell C; Spallek, Markus J; du Toit, Madeleine; Klein, Thorsten; Pasch, Harald

    2016-04-15

    Field flow fractionation (FFF) is an advanced fractionation technique for the analyses of very sensitive particles. In this study, different FFF techniques were used for the fractionation and analysis of polymer emulsions/latexes. As model systems, a pure acrylic emulsion and emulsions containing titanium dioxide were prepared and analyzed. An acrylic emulsion polymerization was conducted, continuously sampled from the reactor and subsequently analyzed to determine the particle size, radius of gyration in specific, of the latex particles throughout the polymerization reaction. Asymmetrical flow field-flow fractionation (AF4) and sedimentation field-flow fractionation (SdFFF), coupled to a multidetector system, multi-angle laser light scattering (MALLS), ultraviolet (UV) and refractive index (RI), respectively, were used to investigate the evolution of particle sizes and particle size distributions (PSDs) as the polymerization progressed. The obtained particle sizes were compared against batch-mode dynamic light scattering (DLS). Results indicated differences between AF4 and DLS results due to DLS taking hydration layers into account, whereas both AF4 and SdFFF were coupled to MALLS detection, hence not taking the hydration layer into account for size determination. SdFFF has additional separation capabilities with a much higher resolution compared to AF4. The calculated radii values were 5nm larger for SdFFF measurements for each analyzed sample against the corresponding AF4 values. Additionally a low particle size shoulder was observed for SdFFF indicating bimodality in the reactor very early during the polymerization reaction. Furthermore, different emulsions were mixed with inorganic species used as additives in cosmetics and coatings such as TiO2. These complex mixtures of species were analyzed to investigate the retention and particle interaction behavior under different AF4 experimental conditions, such as the mobile phase. The AF4 system was coupled online

  13. THE STICKINESS OF MICROMETER-SIZED WATER-ICE PARTICLES

    International Nuclear Information System (INIS)

    Water ice is one of the most abundant materials in dense molecular clouds and in the outer reaches of protoplanetary disks. In contrast to other materials (e.g., silicates), water ice is assumed to be stickier due to its higher specific surface energy, leading to faster or more efficient growth in mutual collisions. However, experiments investigating the stickiness of water ice have been scarce, particularly in the astrophysically relevant micrometer-sized region and at low temperatures. In this work, we present an experimental setup to grow aggregates composed of μm-sized water-ice particles, which we used to measure the sticking and erosion thresholds of the ice particles at different temperatures between 114 K and 260 K. We show with our experiments that for low temperatures (below ∼210 K), μm-sized water-ice particles stick below a threshold velocity of 9.6 m s–1, which is approximately 10 times higher than the sticking threshold of μm-sized silica particles. Furthermore, erosion of the grown ice aggregates is observed for velocities above 15.3 m s–1. A comparison of the experimentally derived sticking threshold with model predictions is performed to determine important material properties of water ice, i.e., the specific surface energy and the viscous relaxation time. Our experimental results indicate that the presence of water ice in the outer reaches of protoplanetary disks can enhance the growth of planetesimals by direct sticking of particles

  14. EFFECTS OF ULTRASOUND ON THE MORPHOLOGY, PARTICLE SIZE, CRYSTALLINITY, AND CRYSTALLITE SIZE OF CELLULOSE

    Directory of Open Access Journals (Sweden)

    SUMARI SUMARI

    2014-05-01

    Full Text Available The aim of this study is to optimize ultrasound treatment to produce fragment of cellulose that is low in particles size, crystallite size, and crystallinity. Slurry of 1 % (w/v the cellulose was sonicated at different time periods and temperatures. An ultrasonic reactor was operated at 300 Watts and 28 kHz to cut down the polymer into smaller particles. We proved that ultrasound damages and fragments the cellulose particles into shorter fibers. The fiber lengths were reduced from in the range of 80-120 µm to 30-50 µm due to an hour ultrasonication and became 20-30 µm after 5 hours. It was also found some signs of erosion on the surface and stringy. The acoustic cavitation also generated a decrease in particle size, crystallinity, and crystallite size of the cellulose along with increasing sonication time but it did not change d-spacing. However, the highest reduction of particle size, crystallite size, and crystallinity of the cellulose occurred within the first hour of ultrasonication, after which the efficiency was decreased. The particle diameter, crystallite size, and crystallinity were decreased from 19.88 µm to 15.96 µm, 5.81 Å to 2.98 Å, and 77.7% to 73.9% respectively due to an hour ultrasound treatment at 40 °C. The treatment that was conducted at 40 °C or 60 °C did not give a different effect significantly. Cellulose with a smaller particle and crystallite size as well as a more amorphous shape is preferred for further study.

  15. Particle size distribution dynamics during precipitative softening: declining solution composition.

    Science.gov (United States)

    Nason, Jeffrey A; Lawler, Desmond F

    2009-02-01

    Particle removal is a critical step in the treatment of surface water for potable use, and the majority of drinking water treatment plants employ precipitative coagulation processes such as alum and iron "sweep-floc" coagulation or lime softening for particle pre-treatment. Unfortunately, little is quantitatively known about how particle size distributions are shaped by simultaneous precipitation and flocculation. In an earlier paper, we demonstrated the effects of the saturation ratio, the mixing intensity and the seed concentration on the rates of homogeneous nucleation, precipitative growth and flocculation during precipitation of calcium carbonate at constant solution composition using electronic particle counting techniques. In this work, we extend those findings to systems more closely emulating the conditions in actual softening processes (i.e., declining solution composition). Key findings include the strong dependence of the rate of flocculation on the initial saturation ratio and demonstration of the benefits of seeding precipitative softening from the perspective of optimizing the effluent particle size distribution. The mixing intensity during precipitation was also shown to strongly influence the final particle size distribution. Implications of the findings with respect to softening practice are discussed. PMID:18976791

  16. Miniaturization of powder dissolution measurement and estimation of particle size.

    Science.gov (United States)

    Avdeef, Alex; Tsinman, Konstantin; Tsinman, Oksana; Sun, Na; Voloboy, Dmytro

    2009-11-01

    The objective was to investigate the applicability and limitations of an approach for estimating particle size from powder dissolution measurement using as little as 50 microg of sample in 1 ml of buffer solutions. The powder dissolution profiles of five sparingly-soluble drugs (hydrochlorothiazide, phenazopyridine hydrochloride, 2-naphthoic acid, indomethacin, and dipyridamole) were evaluated with a novel biexponential spherical particle equation and also the Wang-Flanagan spherical particle non-sink equation. The results were compared to particle sizing based on measured specific surface area by the Brunauer-Emmett-Teller (BET) method, and also based on Coulter counting. With the exception of hydrochlorothiazide, the model compounds indicated some agglomeration in the dissolution media. The dry-state specific surface area was larger than expected from either the Coulter method or the powder-dissolution data, especially for phenazopyridine hydrochloride. The particle radii estimated by the powder dissolution method ranged from 10 to 68 microm, with equilibrium solubilities spanning from 5 microg/ml (dipyridamole) to 911 microg/ml (hydrochlorothiazide). Powder dissolution data collected with the miniaturized apparatus can be used to determine particle size, with estimated values agreeing reasonably with those measured by the Coulter counter method. PMID:19937817

  17. Rock sampling. [method for controlling particle size distribution

    Science.gov (United States)

    Blum, P. (Inventor)

    1971-01-01

    A method for sampling rock and other brittle materials and for controlling resultant particle sizes is described. The method involves cutting grooves in the rock surface to provide a grouping of parallel ridges and subsequently machining the ridges to provide a powder specimen. The machining step may comprise milling, drilling, lathe cutting or the like; but a planing step is advantageous. Control of the particle size distribution is effected primarily by changing the height and width of these ridges. This control exceeds that obtainable by conventional grinding.

  18. Dependence of CO2 absorption on particle size ferroelectric materials

    International Nuclear Information System (INIS)

    We have studied the interaction of carbon dioxide with the surface of ferroelectric oxides such as barium titanate (BaTiO3), potassium niobate (KNb=3) and lithium niobate (LiNbO3). The chemisorption states of CO2 on the surface of KnbO3 and LiNbO3 change when the particles of this material are smaller than 100 microns. The structure of the particles has been defined by x-ray diffraction and Raman spectroscopy, by size. Good correlation was found for the chemisorption properties and for the structural changes for particles smaller than 100 microns. (C.W)

  19. Particle size and velocity measurement in flames by laser anemometer

    Science.gov (United States)

    Chigier, N. A.; Ungut, A.; Yule, A. J.

    1979-01-01

    Simultaneous droplet size and velocity measurements by a particle counting Laser Doppler Anemometer (LDA) in kerosene fuel sprays under burning and non-burning conditions are presented. Particle sizes are derived from pulse height analysis of the mean LDA signals and velocities are simultaneously determined by measuring Doppler shift frequencies. The measurements show that droplet velocity is a function of droplet diameter for burning and non-burning conditions, and spatially averaged size distributions are derived from velocity data. A comparison of results obtained under burning and non-burning conditions show changes in size distribution due to preferential vaporization of small droplets, acceleration due to thermal expansion of gases, and corresponding changes in droplet momentum.

  20. Diffusion of Finite-Size Particles in Confined Geometries

    KAUST Repository

    Bruna, Maria

    2013-05-10

    The diffusion of finite-size hard-core interacting particles in two- or three-dimensional confined domains is considered in the limit that the confinement dimensions become comparable to the particle\\'s dimensions. The result is a nonlinear diffusion equation for the one-particle probability density function, with an overall collective diffusion that depends on both the excluded-volume and the narrow confinement. By including both these effects, the equation is able to interpolate between severe confinement (for example, single-file diffusion) and unconfined diffusion. Numerical solutions of both the effective nonlinear diffusion equation and the stochastic particle system are presented and compared. As an application, the case of diffusion under a ratchet potential is considered, and the change in transport properties due to excluded-volume and confinement effects is examined. © 2013 Society for Mathematical Biology.

  1. Investigation of particles size effects in Dissipative Particle Dynamics (DPD) modelling of colloidal suspensions

    Science.gov (United States)

    Mai-Duy, N.; Phan-Thien, N.; Khoo, B. C.

    2015-04-01

    In the Dissipative Particle Dynamics (DPD) simulation of suspension, the fluid (solvent) and colloidal particles are replaced by a set of DPD particles and therefore their relative sizes (as measured by their exclusion zones) can affect the maximal packing fraction of the colloidal particles. In this study, we investigate roles of the conservative, dissipative and random forces in this relative size ratio (colloidal/solvent). We propose a mechanism of adjusting the DPD parameters to properly model the solvent phase (the solvent here is supposed to have the same isothermal compressibility to that of water).

  2. Airborne measurements of nucleation mode particles I: coastal nucleation and growth rates

    Directory of Open Access Journals (Sweden)

    C. D. O'Dowd

    2007-01-01

    Full Text Available A light aircraft was equipped with a bank of Condensation Particle Counters (CPCs (50% cut from 3–5.4–9.6 nm and a nano-Scanning Mobility Particle Sizer (nSMPS and deployed along the west coast of Ireland, in the vicinity of Mace Head. The objective of the exercise was to provide high resolution micro-physical measurements of the coastal nucleation mode in order to map the spatial extent of new particle production regions and to evaluate the evolution, and associated growth rates of the coastal nucleation-mode aerosol plume. Results indicate that coastal new particle production is occurring over most areas along the land-sea interface with peak concentrations at the coastal plume-head in excess of 106 cm−3. Pseudo-Lagrangian studies of the coastal plume evolution illustrated significant growth of new particles to sizes in excess of 8 nm approximately 10 km downwind of the source region. Close to the plume head (<1 km growth rates can be as high as 123–171 nm h−1, decreasing gradually to 53–72 nm h−1 at 3 km. Further along the plume, at distances up to 10 km, the growth rates are calculated to be 17–32 nm h−1. Growth rates of this magnitude suggest that after a couple of hours, coastal nucleation mode particles can reach significant sizes where they can contribution to the regional aerosol loading.

  3. Particle size distribution of aerosols during sand-blasting of steam turbines

    International Nuclear Information System (INIS)

    Studies were performed to determine the activity median aerodynamic diameter and the solubility classification of radioactive airborne particulates produced during sand blasting of steam turbines at Chin Shan Nuclear Power Station in Taiwan. Cascade impactors were used to collect air samples in the sand blasting house for analyses of particle size and elemental composition. Radionuclides identified in the samples included 60Co, 137Cs, 131I, 140Ba, 140La and 141Ce. These were found to have an activity median aerodynamic diameter of 3 μm to 4 μm, except for volatile 131I, which had a somewhat smaller diameter of 2.8 μm. The major elements composing the aerosols were Si, Fe, Ca, K, Al, and Cr. (author)

  4. Particle size-dependent radical generation from wildland fire smoke

    International Nuclear Information System (INIS)

    Firefighting, along with construction, mining and agriculture, ranks among the most dangerous occupations. In addition, the work environment of firefighters is unlike that of any other occupation, not only because of the obvious physical hazards but also due to the respiratory and systemic health hazards of smoke inhalation resulting from combustion. A significant amount of research has been devoted to studying municipal firefighters; however, these studies may not be useful in wildland firefighter exposures, because the two work environments are so different. Not only are wildland firefighters exposed to different combustion products, but their exposure profiles are different. The combustion products wildland firefighters are exposed to can vary greatly in characteristics due to the type and amount of material being burned, soil conditions, temperature and exposure time. Smoke inhalation is one of the greatest concerns for firefighter health and it has been shown that the smoke consists of a large number of particles. These smoke particles contain intermediates of hydrogen, carbon and oxygen free radicals, which may pose a potential health risk. Our investigation looked into the involvement of free radicals in smoke toxicity and the relationship between particle size and radical generation. Samples were collected in discrete aerodynamic particle sizes from a wildfire in Alaska, preserved and then shipped to our laboratory for analysis. Electron spin resonance was used to measure carbon-centered as well as hydroxyl radicals produced by a Fenton-like reaction with wildfire smoke. Further study of reactive oxygen species was conducted using analysis of cellular H2O2 generation, lipid peroxidation of cellular membranes and DNA damage. Results demonstrate that coarse size-range particles contained more carbon radicals per unit mass than the ultrafine particles; however, the ultrafine particles generated more ·OH radicals in the acellular Fenton-like reaction. The

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

    Science.gov (United States)

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

    2013-05-01

    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 μm-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 μm 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 μm3). 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).

  6. Particle size of a new endodontic cement compared to Root MTA and calcium hydroxide

    OpenAIRE

    Soheilipour, Elham; Kheirieh, Sanam; Madani, Majid; Akbarzadeh Baghban, Alireza; Asgary, Saeed

    2009-01-01

    INTRODUCTION: Particle size and distribution can influence the properties of materials. This study analyzed and compared the particle size of Root MTA, calcium hydroxide (CH), and a new endodontic cement called calcium enriched material (CEM). MATERIALS AND METHODS: The particle size of each material was analyzed three times using 0.05 mg of test material with a particle size analyzer. The particle size distribution ranges, the cumulative percentage and the mean of particle sizes were calcula...

  7. Experimental Effects on IR Reflectance Spectra: Particle Size and Morphology

    Energy Technology Data Exchange (ETDEWEB)

    Beiswenger, Toya N.; Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong; Blake, Thomas A.; Ertel, Alyssa B.; Tonkyn, Russell G.; Szecsody, James E.; Johnson, Timothy J.; Smith, Milton; Lanker, Cory

    2016-05-23

    For geologic and extraterrestrial samples it is known that both particle size and morphology can have strong effects on the species’ infrared reflectance spectra. Due to such effects, the reflectance spectra cannot be predicted from the absorption coefficients alone. This is because reflectance is both a surface as well as a bulk phenomenon, incorporating both dispersion as well as absorption effects. The same spectral features can even be observed as either a maximum or minimum. The complex effects depend on particle size and preparation, as well as the relative amplitudes of the optical constants n and k, i.e. the real and imaginary components of the complex refractive index. While somewhat oversimplified, upward-going amplitude in the reflectance spectrum usually result from surface scattering, i.e. rays that have been reflected from the surface without penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. While the effects are well known, we report seminal measurements of reflectance along with quantified particle size of the samples, the sizing obtained from optical microscopy measurements. The size measurements are correlated with the reflectance spectra in the 1.3 – 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to understand the effects on the spectral features as a function of the mean grain size of the sample. We report results for both sodium sulfate Na2SO4 as well as ammonium sulfate (NH4)2SO4; the optical constants have been measured for (NH4)2SO4. To go a step further from the field to the laboratory we explore our understanding of particle size effects on reflectance spectra in the field using standoff detection. This has helped identify weaknesses and strengths in detection using standoff distances of up 160 meters away from the Target. The studies have

  8. Nano sized clay detected on chalk particle surfaces

    DEFF Research Database (Denmark)

    Skovbjerg, Lone; Hassenkam, Tue; Makovicky, Emil;

    2012-01-01

    that in calcite saturated water, both the polar and the nonpolar functional groups adhere to the nano sized clay particles but not to calcite. This is fundamentally important information for the development of conceptual and chemical models to explain wettability alterations in chalk reservoirs...

  9. Aerosol Particle Size Distributions at a Rural Coastal Site

    NARCIS (Netherlands)

    Leeuw, G. de; Vignati, E.

    1998-01-01

    Aerosol particle size distributions were measured on the Swedish island Ostergamsholm, about 3 km east of Gotland, from 26 April until 13 May, 1998. In this contribution preliminary results are presented of the dialysis of data collected at the south tip of the island at 10 m above sea level using a

  10. Particle size and packing characterization by diffuse light transmission

    Institute of Scientific and Technical Information of China (English)

    Henrik Ehlers; Jyrki Hein(a)m(a)ki; Jouko Yliruusi

    2012-01-01

    Particle size,packing density and blend composition of glass ballotini,microcrystalline cellulose pellets and theophylline granules were studied by diffuse light transmission.Diffuse visible light was directed to the sample and the intensity of the light transmitted to the opposite side of the sample was measured through a diffusing lens using a phototransistor.Light transmission was found to decrease with decreasing particle size and with increasing packing density.There was a correlation,though somewhat irregular,between light transmission and particle size for glass ballotini and microcrystalline cellulose pellets,and a strong near-linear correlation between light transmission and particle size for theophylline granules.The effect of packing density on light transmission was significant.Differentiating the composition of binary blends of microcrystalline cellulose pellets and glass ballotini and blends of theophylline granules was found possible on the basis of light transmission.The method proposed showed potential as a rapid,simple and inexpensive analytical tool for basic process diagnostics.

  11. Tracing Particle Size Distribution Curves Using an Analogue Circuit.

    Science.gov (United States)

    Bisschop, F. De; Segaert, O.

    1986-01-01

    Proposes an analog circuit for use in sedimentation analysis of finely divided solid materials. Discusses a method of particle size distribution analysis and provides schematics of the circuit with list of components as well as a discussion about the operation of the circuit. (JM)

  12. Comparison of ice particle size variations across Ganymede and Callisto

    Science.gov (United States)

    Stephan, Katrin; Hoffmann, Harald; Hibbitts, Karl; Wagner, Roland; Jaumann, Ralf

    2016-04-01

    Ratios of band depths of different H2O ice absorptions as measured by the Near Infrared Spectrometer NIMS onboard the Galileo spacecraft [1] have been found to be semi-quantitative indicator of changes in the particle size of ice across the surfaces of the Jovian satellite Ganymede [2]. This method is now applied to Ganymede's neighboring satellite Callisto. On Ganymede, sizes reach from 1 μm near the poles to 1 mm near the equator [2]. Smallest particles occur at latitudes higher than ±30° where the closed magnetic field lines of Ganymede's magnetic field change into open ones and Ganymede's polar caps become apparent. Thus, the formation of these polar caps has often been attributed to brightening effects due to plasma bombardment of the surface [3,4]. Callisto, which does not exhibit an intrinsic magnetic field, however, also shows the same trend as observed on Ganymede with slightly larger particle sizes on Callisto than on Ganymede at low and mid latitude but similar particle sizes in the polar regions. Similar trends in the particle size variations on Callisto and on Ganymede imply that these variations are caused by similar surface processes. Our measurements rather point to a continuous decreasing of ice particle sizes toward the poles on both satellites related to changes of the surface temperatures [5]. Maximum temperatures during the day reach 150 K and 165 K near the equator of Ganymede and Callisto [6, 7], respectively and sublimation of ice particles and crystal growth [8] is expected to be the dominant surface process in these regions. In contrast, polar temperatures do not exceed 80 ± 5 K [5]. Larger particles in the equatorial region of Callisto than on Ganymede could be explained due to the slight higher maximum temperature but also a longer Callistoan day (Callisto: ~ 17 Earth days; Ganymede: ~ 7 Earth days). References: [1] Carlson et al.. (1999) Science 274, 385-388, 1996; [2] Stephan et al., 2009, EPSC, Abstract #EPSC2009-633; [3] Johnson

  13. Evolution of Particle Size Distributions in Fragmentation Over Time

    Science.gov (United States)

    Charalambous, C. A.; Pike, W. T.

    2013-12-01

    We present a new model of fragmentation based on a probabilistic calculation of the repeated fracture of a particle population. The resulting continuous solution, which is in closed form, gives the evolution of fragmentation products from an initial block, through a scale-invariant power-law relationship to a final comminuted powder. Models for the fragmentation of particles have been developed separately in mainly two different disciplines: the continuous integro-differential equations of batch mineral grinding (Reid, 1965) and the fractal analysis of geophysics (Turcotte, 1986) based on a discrete model with a single probability of fracture. The first gives a time-dependent development of the particle-size distribution, but has resisted a closed-form solution, while the latter leads to the scale-invariant power laws, but with no time dependence. Bird (2009) recently introduced a bridge between these two approaches with a step-wise iterative calculation of the fragmentation products. The development of the particle-size distribution occurs with discrete steps: during each fragmentation event, the particles will repeatedly fracture probabilistically, cascading down the length scales to a final size distribution reached after all particles have failed to further fragment. We have identified this process as the equivalent to a sequence of trials for each particle with a fixed probability of fragmentation. Although the resulting distribution is discrete, it can be reformulated as a continuous distribution in maturity over time and particle size. In our model, Turcotte's power-law distribution emerges at a unique maturation index that defines a regime boundary. Up to this index, the fragmentation is in an erosional regime with the initial particle size setting the scaling. Fragmentation beyond this index is in a regime of comminution with rebreakage of the particles down to the size limit of fracture. The maturation index can increment continuously, for example under

  14. Interactions, particle size and surface effects in magnetic nanoparticle systems

    Energy Technology Data Exchange (ETDEWEB)

    Blanco-Mantecon, M

    2000-02-01

    This work has involved the study of the magnetic behaviour of small magnetic nanoparticle systems. Due to the reduced size of magnetic nanoparticles they present distinctive properties, such as size and surface effects, that have been analysed in this work, as well as the effect of interactions in such systems. The samples chosen for the study were magnetite particles in the form of a ferrofluid and Co nanoclusters in a nonmagnetic matrix of Cu. Both systems present very narrow particle size distributions, which facilitates the interpretation of the data. The samples have been subjected to basic characterisation, which includes the determination of the distribution of magnetic particle sizes using the magnetisation curves at room temperatures, TEM microscopy and X-ray diffraction, in the case of the ferrofluid samples. For the nanoclusters, a time of flight spectrometer has been used to obtain the number of atoms per cluster. Many of the measurements have been performed at low temperatures, where thermal effects are minimised. For such measurements the samples have been frozen in a zero applied field, so that they have a random distribution of magnetic moments prior to the measurement. The energy barrier distributions have been calculated via the temperature decay of remanence (TDR). From this study, an effective anisotropy constant has been calculated. For the study of the interactions, surface and size effects, magnetisation, susceptibility (ZFC), remanence and delta-M curves, as well as the time dependence of magnetisation have been studied. The attempt frequency of the different particle size systems has been calculated using different techniques. The basic magnetic behaviour can be explained on the basis of the Neel blocking model. It has been found that the systems with the smaller particles have significant surface effects, which are enhanced at lower temperatures. Interactions, which are weak due to the low concentration of magnetic material in the samples

  15. Size-dependent dielectrophoretic crossover frequency of spherical particles.

    Science.gov (United States)

    Weng, Ping-You; Chen, I-An; Yeh, Che-Kai; Chen, Pin-Yi; Juang, Jia-Yang

    2016-01-01

    Dielectrophoresis (DEP) has been extensively used in lab-on-a-chip systems for trapping, separating, and manipulating of micro particles suspended in a liquid medium. The most widely used analytic model, the dipole model, provides an accurate prediction on the crossover frequency of submicron particles, but cannot explain the significant drop in crossover frequency of larger particles. Here, we present numerical simulations using the Maxwell stress tensor (MST) and finite element method to study the size effect of the DEP crossover frequency of spherical polystyrene particles suspended in de-ionized water. Our results show that the surface conductance due to the electrical double layer plays a key role, and the size dependency of crossover frequency obtained by the MST method agrees reasonably well with published experimental data. The exponents of the power law are approximately -1.0 and -4.3 for smaller (diameter  4.6 μm), respectively. The free surface charge distribution reveals that the charge begins accumulating on the particle equator for particle diameters larger than a critical diameter of 4.6 μm, a result not captured by the dipolar approximation. This method may be extended to analyze bioparticles with complex shapes and composition, and provides new insights into the interpretation of dielectrophoresis applications using lab-on-a-chip systems. PMID:26909121

  16. The white-light humidified optical particle spectrometer (WHOPS – a novel airborne system to characterize aerosol hygroscopicity

    Directory of Open Access Journals (Sweden)

    B. Rosati

    2014-07-01

    3% and maximal deviation of 9% for GFs at RH = 95%. First airborne measurements in the Netherlands observed GFs (mean value of the GF distribution at RH = 95% between 1.74 and 2.67 with a median of 1.94 for particles with a dry diameter of 500 nm. This corresponds to hygroscopicity parameters (κ between 0.21 and 0.93 with a median of 0.33. The GF distributions indicate externally mixed particles covering the whole range of GFs between ~ 1.0–3.0. On average ~ 74% of the particles were "more hygroscopic" with GFs > 1.5, ~ 15% were non- or slightly hygroscopic with GF 2, indicating influence of sea salt particles, consistent with previous ground-based particle hygroscopicity measurements in this area. The mean dry effective index of refraction for 500 nm particles was found to be rather constant with a value of 1.42 ± 0.04.

  17. Ultrasonic cavitation for obtainment of nanometric sized particles

    Science.gov (United States)

    Santos, A.; Guzmán, R.; Espinosa, J.; Estrada, J.

    2016-02-01

    This project aims to determine the possibility of obtaining nanometric size particles of aluminium oxide (Al2O3) and titanium dioxide (TiO2) from commercial micron-sized powders, through the physical principle of ultrasonic cavitation, in order to be used as supply material in coatings made through a process of thermal spray by flame. The tests are performed on a Hielscher UIP 1000hd Ultrasonics equipment, in a 20 micron wave amplitude and in times of 6, 8, 12, 18 and 24 hours. The determination of the particle size is done through image processing using ImageJ software, obtained by the technique of scanning electron microscopy (SEM); while the elemental composition of the processed samples is analyzed through the technique of energy dispersing spectroscopy (EDS). The results show that Al2O3 and TiO2 have a reduction behaviour of the particles size after being subjected to ultrasonic cavitation, however is only reached the nanometric size in the TiO2 samples.

  18. Particle size, porosity and temperature effects on char conversion

    International Nuclear Information System (INIS)

    Highlights: → Effect of particle size, porosity and temperature on char conversion is investigated. → Kinetic parameters have been obtained using a chemically controlled experiment. → Transport equation inside the char particle was solved using finite element method. → Large Damkohler number resulted in steep gasifying agent concentration profiles. → Small Damkohler number resulted in constant gasifying agent concentration profile. -- Abstract: The effect of particle size, porosity and reactor temperature/reaction rate constant on the progress of a char particle conversion has been investigated numerically by solving the transport equation inside a reacting char particle. Numerical simulations have been conducted for three cases that include two extreme cases and one general case. The two extreme cases correspond to a very large Damkohler number (3.2607 x 103) and a very small Damkohler number (0.0042). The third case corresponds to an intermediate value of Damkohler number. For the very large Damkohler number case, concentration profiles of the gasifying agent showed a steep gradient across the particle and the reaction occurred mostly in outer layer of the particle. This behavior corresponds to a diffusion controlled process. For the very small Damkohler number case, gasifying agent concentration was a straight line parallel to the x-axis, with a y-axis value of the surrounding concentration. The reaction occurred homogeneously across the particle and the degree of conversion was only a function in time. This behavior corresponds to a chemically controlled process. The total conversion of the char particle as a function of time has also been calculated for different particle sizes, initial porosity and reaction rate constant. Variation in conversion profiles as a function of time due to variation in initial porosity and reaction rate constant were limited to a certain extent. Very high initial porosity values tend to shift the process towards a

  19. Monitoring and evaluation techniques for airborne contamination

    Energy Technology Data Exchange (ETDEWEB)

    Xia Yihua [China Inst. of Atomic Energy, Beijing (China)

    1997-06-01

    Monitoring and evaluation of airborne contamination are of great importance for the purpose of protection of health and safety of workers in nuclear installations. Because airborne contamination is one of the key sources to cause exposure to individuals by inhalation and digestion, and to cause diffusion of contaminants in the environment. The main objectives of monitoring and evaluation of airborne contamination are: to detect promptly a loss of control of airborne material, to help identify those individuals and predict exposure levels, to assess the intake and dose commitment to the individuals, and to provide sufficient documentation of airborne radioactivity. From the viewpoint of radiation protection, the radioactive contaminants in air can be classified into the following types: airborne aerosol, gas and noble gas, and volatile gas. In this paper, the following items are described: sampling methods and techniques, measurement and evaluation, and particle size analysis. (G.K.)

  20. The influence of particle size on the fracture toughness of a PP-based particle composite

    Czech Academy of Sciences Publication Activity Database

    Hutař, Pavel; Majer, Zdeněk; Šestáková, Lucie; Náhlík, Luboš; Knésl, Zdeněk

    Riga, Latvia : Institute of Polymer Mechanics, University of Latvia, 2008. s. 112-112. [Mechanics of Composite Materials 2008. 26.05.2008-30.05.2008, Riga] R&D Projects: GA ČR GA106/07/1284 Institutional research plan: CEZ:AV0Z20410507 Keywords : PP-based particle composite * particle size * fracture toughness Subject RIV: JI - Composite Materials

  1. Totally asymmetric exclusion processes with particles of arbitrary size

    CERN Document Server

    Lakatos, G

    2003-01-01

    The steady-state currents and densities of a one-dimensional totally asymmetric exclusion process (TASEP) with particles that occlude an integer number (d) of lattice sites are computed using various mean-field approximations and Monte Carlo simulations. TASEPs featuring particles of arbitrary size are relevant for modelling systems such as mRNA translation, vesicle locomotion along microtubules and protein sliding along DNA. We conjecture that the nonequilibrium steady-state properties separate into low-density, high-density, and maximal current phases similar to those of the standard (d = 1) TASEP. A simple mean-field approximation for steady-state particle currents and densities is found to be inaccurate. However, we find local equilibrium particle distributions derived from a discrete Tonks gas partition function yield apparently exact currents within the maximal current phase. For the boundary-limited phases, the equilibrium Tonks gas distribution cannot be used to predict currents, phase boundaries, or ...

  2. Beryllium solubility in occupational airborne particles: Sequential extraction procedure and workplace application.

    Science.gov (United States)

    Rousset, Davy; Durand, Thibaut

    2016-01-01

    Modification of an existing sequential extraction procedure for inorganic beryllium species in the particulate matter of emissions and in working areas is described. The speciation protocol was adapted to carry out beryllium extraction in closed-face cassette sampler to take wall deposits into account. This four-step sequential extraction procedure aims to separate beryllium salts, metal, and oxides from airborne particles for individual quantification. Characterization of the beryllium species according to their solubility in air samples may provide information relative to toxicity, which is potentially related to the different beryllium chemical forms. Beryllium salts (BeF(2), BeSO(4)), metallic beryllium (Bemet), and beryllium oxide (BeO) were first individually tested, and then tested in mixtures. Cassettes were spiked with these species and recovery rates were calculated. Quantitative analyses with matched matrix were performed using inductively coupled plasma mass spectrometry (ICP-MS). Method Detection Limits (MDLs) were calculated for the four matrices used in the different extraction steps. In all cases, the MDL was below 4.2 ng/sample. This method is appropriate for assessing occupational exposure to beryllium as the lowest recommended threshold limit values are 0.01 µg.m(-3) in France([) (1) (]) and 0.05 µg.m(-3) in the USA.([ 2 ]) The protocol was then tested on samples from French factories where occupational beryllium exposure was suspected. Beryllium solubility was variable between factories and among the same workplace between different tasks. PMID:26327570

  3. Particle size dependent rheological property in magnetic fluid

    Science.gov (United States)

    Wu, Jie; Pei, Lei; Xuan, Shouhu; Yan, Qifan; Gong, Xinglong

    2016-06-01

    The influence of the particle size on the rheological property of magnetic fluid was studied both by the experimental and computer simulation methods. Firstly, the magnetic fluids were prepared by dispersing Fe3O4 nanospheres with size varied from 40 nm to 100 nm and 200 nm in the solution. Then, the rheological properties were investigated and it was found that the relative magnetorheological effects increased with increasing the particle size. Finally, the molecular dynamic simulation was used to analyze the mechanical characteristics of the magnetic fluid and the chain-like model agreed well with the experimental result. The authentic chain-like structure observed by a microscope agreed with the simulation results. The three particles composed of the similar cluster nanostructure, thus they exhibited similar magnetic property. To this end, the unique assembling microstructures was the origination of the mechanical difference. And it was found that the higher MR (magnetorheological) effects of the large particle based magnetic fluid was originated from the stronger assembling microstructure under the applying magnetic field.

  4. Surface Chemistry at Size-Selected Nano-Aerosol Particles

    Science.gov (United States)

    Roberts, Jeffrey

    2005-03-01

    A method has been developed to conduct surface chemistry and extract surface kinetic rates from size-selected aerosol nanoparticles. The measurements encompass broad ranges of particle size, phase, and composition. Results will be presented on the uptake of water by aerosolized soot nanoparticles of radius between 10 and 40 nm. Water uptake was monitored by tandem differential mobility analysis (T-DMA), which is capable of measuring changes in particle diameter as little as 0.2 nm. Soot particles were produced in an ethene diffusion flame and extracted into an atmospheric pressure aerosol flow tube reactor. The particles were subjected to various thermal and oxidative treatments, and the effects of these treatments on the ability of soot to adsorb monolayer quantities of water was determined. The results are important because soot nucleates atmospheric cloud particles. More generally, the results represent one of the first kinetic and mechanistic studies of gas-phase nanoparticle reactivity. Co-author: Henry Ajo, University of Minnesota

  5. The Size Distribution of Arecibo Interstellar Particles and Its Implications

    Science.gov (United States)

    Meisel, David D.; Janches, Diego; Mathews, John D.

    2002-11-01

    Size histograms of all Arecibo ultra-high-frequency radar micrometeors detected in 1997-1998 whose radii were measured by atmospheric drag are presented. Most can be fitted with either a lognormal function or, alternatively, one or more power-law functions. Either form is indicative of significant fragmentation. The interplanetary dust particle (IDP) histogram results are discussed and compared with those considered to be extrasolar particles, including a subset of those deemed to be true interstellar particles (ISPs). The Arecibo IDP power-law results are shown to agree well with those derived from IRAS dust bands and Long-Duration Exposure Facility cratering, thus confirming the applicability of the sample to the derivation of mass estimates. A dichotomy between size histograms of particles with preperihelion Earth encounters and those with postperihelion encounters is evidence that significant size histogram change occurs when the smallest particles, including all ISPs, pass close to the Sun, even if only once. A small sample of previously undetected Arecibo postperihelion ISPs coming from the direction of the known Ulysses gas and dust flow are shown to have a size distribution and solar system dynamical properties similar to other Arecibo ISPs and therefore can be combined with previous ISP results to obtain a more robust sample. Derived mass flux points for the Arecibo ISPs agree well (over 5 orders of magnitude of mass) with a previously derived mass flux distribution function for Ulysses/Galileo spacecraft dust. This combined spacecraft and ground-based mass flux function is then used to infer a number of interesting mass-related solar system and astrophysical quantities.

  6. Theory of flotation of small and medium-size particles

    Science.gov (United States)

    Derjaguin, B. V.; Dukhin, S. S.

    1993-08-01

    The paper describes a theory of flotation of small and medium-size particles less than 50μ in radius) when their precipitation on a bubble surface depends more on surface forces than on inertia forces, and deformation of the bubble due to collisions with the particles may be neglected. The approach of the mineral particle to the bubble surface is regarded as taking place in three stages corresponding to movement of the particles through zones 1, 2 and 3. Zone 3 is a liquid wetting layer of such thickness that a positive or negative disjoining pressure arises in this intervening layer between the particle and the bubble. By zone 2 is meant the diffusional boundary layer of the bubble. In zone 1, which comprises the entire liquid outside zone 2, there are no surface forces. Precipitation of the particles is calculated by considering the forces acting in zones 1, 2 and 3. The particles move through zone 1 under the action of gravity and inertia. Analysis of the movement of the particles under the action of these forces gives the critical particle size, below which contact with the bubble surface is impossible, if the surface forces acting in zones 2 and 3 be neglected. The forces acting in zone 2 are ‘diffusio-phoretic’ forces due to the concentration gradient in the diffusional boundary layer. The concentration and electric field intensity distribution in zone 2 is calculated, taking into account ion diffusion to the deformed bubble surface. An examination is made of the ‘equilibrium’ surface forces acting in zone 3 independent of whether the bubble is at rest or in motion. These forces, which determine the behaviour of the thin wetting intervening layer between the bubble and the mineral particle and the height of the force barrier against its rupture, may be represented as results of the disjoining pressure forces acting on various parts of the film. The main components of the disjoining pressure are van der Waals forces, forces of an iono

  7. Health effects of daily airborne particle dose in children: Direct association between personal dose and respiratory health effects

    International Nuclear Information System (INIS)

    Air pollution is a widespread health problem associated with respiratory symptoms. Continuous exposure monitoring was performed to estimate alveolar and tracheobronchial dose, measured as deposited surface area, for 103 children and to evaluate the long-term effects of exposure to airborne particles through spirometry, skin prick tests and measurement of exhaled nitric oxide (eNO). The mean daily alveolar deposited surface area dose received by children was 1.35 × 103 mm2. The lowest and highest particle number concentrations were found during sleeping and eating time. A significant negative association was found between changes in pulmonary function tests and individual dose estimates. Significant differences were found for asthmatics, children with allergic rhinitis and sensitive to allergens compared to healthy subjects for eNO. Variation is a child's activity over time appeared to have a strong impact on respiratory outcomes, which indicates that personal monitoring is vital for assessing the expected health effects of exposure to particles. -- Highlights: •Particle dose was estimated through personal monitoring on more than 100 children. •We focused on real-time daily dose of particle alveolar deposited surface area. •Spirometry, skin prick and exhaled Nitric Oxide tests were performed. •Negative link was found between changes in pulmonary functions and individual doses. •A child's lifestyle appeared to have a strong impact on health respiratory outcomes. -- The respiratory health effects of daily airborne particle dose on children through personal monitoring

  8. Infrared reflectance spectra: Effects of particle size, provenance and preparation

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yin-Fong; Myers, Tanya L.; Brauer, Carolyn S.; Blake, Thomas A.; Forland, Brenda M.; Szecsody, James E.; Johnson, Timothy J.

    2014-09-22

    We have recently developed methods for making more accurate infrared total and diffuse directional - hemispherical reflectance measurements using an integrating sphere. We have found that reflectance spectra of solids, especially powders, are influenced by a number of factors including the sample preparation method, the particle size and morphology, as well as the sample origin. On a quantitative basis we have investigated some of these parameters and the effects they have on reflectance spectra, particularly in the longwave infrared. In the IR the spectral features may be observed as either maxima or minima: In general, upward-going peaks in the reflectance spectrum result from strong surface scattering, i.e. rays that are reflected from the surface without bulk penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. The light signals reflected from solids usually encompass all such effects, but with strong dependencies on particle size and preparation. This paper measures the reflectance spectra in the 1.3 – 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to observe the effects on the spectral features: Bulk materials were ground with a mortar and pestle and sieved to separate the samples into various size fractions between 5 and 500 microns. The median particle size is demonstrated to have large effects on the reflectance spectra. For certain minerals we also observe significant spectral change depending on the geologic origin of the sample. All three such effects (particle size, preparation and provenance) result in substantial change in the reflectance spectra for solid materials; successful identification algorithms will require sufficient flexibility to account for these parameters.

  9. Photothermal imaging of nanometer-sized metal particles among scatterers.

    Science.gov (United States)

    Boyer, David; Tamarat, Philippe; Maali, Abdelhamid; Lounis, Brahim; Orrit, Michel

    2002-08-16

    Ambient optical detection of labeled molecules is limited for fluorescent dyes by photobleaching and for semiconducting nanoparticles by "blinking" effects. Because nanometer-sized metal particles do not optically bleach, they may be useful optical labels if suitable detection signals can be found. We demonstrate far-field optical detection of gold colloids down to diameters of 2.5 nanometers with a photothermal method that combines high-frequency modulation and polarization interference contrast. The photothermal image is immune to the effects of scattering background, which limits particle imaging through Rayleigh scattering to diameters larger than 40 nanometers. PMID:12183624

  10. On the size and composition of particles in polar stratospheric clouds

    Science.gov (United States)

    Kinne, Stefan; Toon, Owen B.; Toon, Goeff C.; Farmer, Crofton B.; Browell, Edward V.

    1988-01-01

    Attenuation measurements of the solar radiation between 1.5 and 15 micron wavelengths were performed with the airborne (DC-8) JPL MARK 4 interferometer during the 1987 Antarctic Expedition. The opacities not only provide information about the abundance of stratospheric gases but also about the optical depths of polar stratospheric clouds (PSCs) at wavelengths of negligible gas absorption (windows). The optical depth of PSCs can be determined for each window once the background attenuation, due to air-molecules and aerosol has been filtered out with a simple extinction law. The ratio of optical thicknesses at different wavelengths reveals information about particle size and particle composition. Among the almost 700 measured spectra only a few PSC cases exist. PSC events are identified by sudden reductions in the spectrally integrated intensity value and are also verified with backscattering data from an upward directed lidar instrument, that was mounted on the DC-8. For the selected case on September 21st at 14.40 GMT, lidar data indicate an optically thin cloud at 18k and later an additional optically thick cloud at 15 km altitude. All results still suffer from: (1) often arbitrary definitions of a clear case, that often already may have contained PSC particles and (2) noise problems that restrict the calculations of optical depths to values larger than 0.001. Once these problems are handled, this instrument may become a valuable tool towards a better understanding of the role PSCs play in the Antarctic stratosphere.

  11. Particle size distributions of particulate emissions from the ferroalloy industry evaluated by electrical low pressure impactor (ELPI).

    Science.gov (United States)

    Kero, Ida; Naess, Mari K; Tranell, Gabriella

    2015-01-01

    The present article presents a comprehensive evaluation of the potential use of an Electrical Low Pressure Impactor (ELPI) in the ferroalloy industry with respect to indoor air quality and fugitive emission control. The ELPI was used to assess particulate emission properties, particularly of the fine particles (Dp ≤ 1 μm), which in turn may enable more satisfactory risk assessments for the indoor working conditions in the ferroalloy industry. An ELPI has been applied to characterize the fume in two different ferroalloy plants, one producing silicomanganese (SiMn) alloys and one producing ferrosilicon (FeSi) alloys. The impactor classifies the particles according to their aerodynamic diameter and gives real-time particle size distributions (PSD). The PSD based on both number and mass concentrations are shown and compared. Collected particles have also been analyzed by transmission and scanning electron microscopy with energy dispersive spectroscopy. From the ELPI classification, particle size distributions in the range 7 nm - 10 μm have been established for industrial SiMn and FeSi fumes. Due to the extremely low masses of the ultrafine particles, the number and mass concentration PSD are significantly different. The average aerodynamic diameters for the FeSi and the SiMn fume particles were 0.17 and 0.10 μm, respectively. Based on this work, the ELPI is identified as a valuable tool for the evaluation of airborne particulate matter in the indoor air of metallurgical production sites. The method is well suited for real-time assessment of morphology (particle shape), particle size, and particle size distribution of aerosols. PMID:25380385

  12. Reconciliation of coarse mode sea-salt aerosol particle size measurements and parameterizations at a subtropical ocean receptor site

    Science.gov (United States)

    Reid, Jeffrey S.; Brooks, Barbara; Crahan, Katie K.; Hegg, Dean A.; Eck, Thomas F.; O'Neill, Norm; de Leeuw, Gerrit; Reid, Elizabeth A.; Anderson, Kenneth D.

    2006-01-01

    In August/September of 2001, the R/P FLIP and CIRPAS Twin Otter research aircraft were deployed to the eastern coast of Oahu, Hawaii, as part of the Rough Evaporation Duct (RED) experiment. Goals included the study of the air/sea exchange, turbulence, and sea-salt aerosol particle characteristics at the subtropical marine Pacific site. Here we examine coarse mode particle size distributions. Similar to what has been shown for airborne dust, optical particle counters such as the Forward Scattering Spectrometer Probe (FSSP), Classical Scattering Aerosol Spectrometer Probe (CSASP) and the Cloud Aerosol Spectrometer (CAS) within the Cloud Aerosol and Precipitation Spectrometer (CAPS) instrument systematically overestimate particle size, and consequently volume, for sea salt particles. Ground-based aerodynamic particle sizers (APS) and AERONET inversions yield much more reasonable results. A wing pod mounted APS gave mixed results and may not be appropriate for marine boundary layer studies. Relating our findings to previous studies does much to explain the bulk of the differences in the literature and leads us to conclude that the largest uncertainty facing flux and airborne cloud/aerosol interaction studies is likely due to the instrumentation itself. To our knowledge, there does not exist an in situ aircraft system that adequately measures the ambient volume distribution of coarse mode sea salt particles. Most empirically based sea salt flux parameterizations can trace their heritage to a clearly biased measurement technique. The current "state of the art" in this field prevents any true form of clear sky radiative "closure" for clean marine environments.

  13. Characterizing the impact of urban emissions on regional aerosol particles: airborne measurements during the MEGAPOLI experiment

    Science.gov (United States)

    Freney, E. J.; Sellegri, K.; Canonaco, F.; Colomb, A.; Borbon, A.; Michoud, V.; Doussin, J.-F.; Crumeyrolle, S.; Amarouche, N.; Pichon, J.-M.; Bourianne, T.; Gomes, L.; Prevot, A. S. H.; Beekmann, M.; Schwarzenböeck, A.

    2014-02-01

    The MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) experiment took place in July 2009. The aim of this campaign was to study the aging and reactions of aerosol and gas-phase emissions in the city of Paris. Three ground-based measurement sites and several mobile platforms including instrument equipped vehicles and the ATR-42 aircraft were involved. We present here the variations in particle- and gas-phase species over the city of Paris, using a combination of high-time resolution measurements aboard the ATR-42 aircraft. Particle chemical composition was measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), giving detailed information on the non-refractory submicron aerosol species. The mass concentration of black carbon (BC), measured by a particle absorption soot photometer (PSAP), was used as a marker to identify the urban pollution plume boundaries. Aerosol mass concentrations and composition were affected by air-mass history, with air masses that spent longest time over land having highest fractions of organic aerosol and higher total mass concentrations. The Paris plume is mainly composed of organic aerosol (OA), BC, and nitrate aerosol, as well as high concentrations of anthropogenic gas-phase species such as toluene, benzene, and NOx. Using BC and CO as tracers for air-mass dilution, we observe the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase with increasing photochemical age (-log(NOx / NOy)). Plotting the equivalent ratios of different organic aerosol species (LV-OOA, SV-OOA, and HOA) illustrate that the increase in OA is a result of secondary organic aerosol (SOA) formation. Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in London, Mexico City, and in New England, USA. Using the measured SOA volatile organic compounds (VOCs) species together with organic aerosol formation

  14. Inversion method based on stochastic optimization for particle sizing.

    Science.gov (United States)

    Sánchez-Escobar, Juan Jaime; Barbosa-Santillán, Liliana Ibeth; Vargas-Ubera, Javier; Aguilar-Valdés, Félix

    2016-08-01

    A stochastic inverse method is presented based on a hybrid evolutionary optimization algorithm (HEOA) to retrieve a monomodal particle-size distribution (PSD) from the angular distribution of scattered light. By solving an optimization problem, the HEOA (with the Fraunhofer approximation) retrieves the PSD from an intensity pattern generated by Mie theory. The analyzed light-scattering pattern can be attributed to unimodal normal, gamma, or lognormal distribution of spherical particles covering the interval of modal size parameters 46≤α≤150. The HEOA ensures convergence to the near-optimal solution during the optimization of a real-valued objective function by combining the advantages of a multimember evolution strategy and locally weighted linear regression. The numerical results show that our HEOA can be satisfactorily applied to solve the inverse light-scattering problem. PMID:27505357

  15. Size-segregated compositional analysis of aerosol particles collected in the European Arctic during the ACCACIA campaign

    Science.gov (United States)

    Young, G.; Jones, H. M.; Darbyshire, E.; Baustian, K. J.; McQuaid, J. B.; Bower, K. N.; Connolly, P. J.; Gallagher, M. W.; Choularton, T. W.

    2016-03-01

    Single-particle compositional analysis of filter samples collected on board the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft is presented for six flights during the springtime Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign (March-April 2013). Scanning electron microscopy was utilised to derive size-segregated particle compositions and size distributions, and these were compared to corresponding data from wing-mounted optical particle counters. Reasonable agreement between the calculated number size distributions was found. Significant variability in composition was observed, with differing external and internal mixing identified, between air mass trajectory cases based on HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) analyses. Dominant particle classes were silicate-based dusts and sea salts, with particles notably rich in K and Ca detected in one case. Source regions varied from the Arctic Ocean and Greenland through to northern Russia and the European continent. Good agreement between the back trajectories was mirrored by comparable compositional trends between samples. Silicate dusts were identified in all cases, and the elemental composition of the dust was consistent for all samples except one. It is hypothesised that long-range, high-altitude transport was primarily responsible for this dust, with likely sources including the Asian arid regions.

  16. Short-term mechanisms of toxic action of airborne particulates underlie dose-rate dependent health risks and support control of one-hour airborne particle levels

    Energy Technology Data Exchange (ETDEWEB)

    Michaels, R.A.; Kleinman, M.T.

    1999-07-01

    Twenty-four-hour airborne particle mass levels permissible under the NAAQS have been associated with mortality and morbidity in communities, motivating reconsideration of the standard. Reports of shorter-term mechanisms of toxic action exerted by airborne PM and PM constituents are emerging. The mechanisms are diverse, but have in common a short time frame of toxic action, from minutes to hours. In view of documented PM excursions also lasting minutes to hours, this study inquires whether such short-term mechanisms might contribute to explaining daily morbidity and mortality. Toxicology experiments have demonstrated the harmfulness of brief exposure to PM levels in the range of observed excursions. This suggests that toxicological processes initiated by short-term inhalation of PM may exert clinically important effects, and that weak associations of 24-hour-average particle mass with mortality and morbidity may represent artifacts of stronger, shorter-term associations whose full magnitude remains to be quantified. In one study, the area of lung surface developing lesions was elevated in rats breathing the same four-hour dose of aerosols, when the four-hour average rate of aerosol delivery included a short-term (five-minute) burst fifty percent above the average dose rate. Elevations were observed with each of two aerosols tested. The magnitude of the effect was higher with one of the two aerosols, whose dose rate included four excursions rather than just one excursion. Particulate matter inhaled or instilled intratracheally has produced morbidity in animals, including apnea and electrophysiological effects in dogs. Other studies reveal that PM can kill rats via electrophysiological and possibly other mechanisms. PM has also adversely affected asthmatic people in controlled clinical settings during exercise or, in one study, at rest.

  17. Particle size distribution dynamics during precipitative softening: constant solution composition.

    Science.gov (United States)

    Nason, Jeffrey A; Lawler, Desmond F

    2008-08-01

    In the treatment of surface water for potable use, precipitative coagulation (e.g., lime softening, alum or iron sweep coagulation) is widely utilized prior to particle removal processes. The particle size distribution (PSD) formed during such processes is a prime determinant of the removal efficiency for suspended and dissolved contaminants, but little is known quantitatively about how PSDs change by simultaneous precipitation and flocculation. Using precipitative softening as an example, detailed measurements of the PSD (using electronic particle counting) were made during precipitation of CaCO(3) under conditions of constant solution composition. Examination of the time-varying PSDs revealed dramatic changes resulting from nucleation, crystal growth, and flocculation. The influence of the saturation ratio, seed concentration, and mixing intensity on those processes was quantified. Implications with respect to the design and operation of water treatment facilities are discussed. PMID:18656223

  18. Thermal levitation of 10 um size particles in low vacuum

    Science.gov (United States)

    Fung, Long Fung Frankie; Kowalski, Nicholas; Parker, Colin; Chin, Cheng

    2016-05-01

    We report on experimental methods for trapping 10 micron-sized ice, glass, ceramic and polyethylene particles with thermophoresis in medium vacuum, at pressures between 5 Torr and 25 Torr. Under appropriate conditions particles can launch and levitate robustly for up to an hour. We describe the experimental setup used to produce the temperature gradient necessary for the levitation, as well as our procedure for generating and introducing ice into the experimental setup. In addition to analyzing the conditions necessary for levitation, and the dependence of levitation on the experimental parameters, we report on the behavior of particles during levitation and ejection, including position and stability, under different pressures and temperatures. We also note a significant discrepancy between theory and data, suggesting the presence of other levitating forces.

  19. Building predictive models of soil particle-size distribution

    OpenAIRE

    Alessandro Samuel-Rosa; Ricardo Simão Diniz Dalmolin; Pablo Miguel

    2013-01-01

    Is it possible to build predictive models (PMs) of soil particle-size distribution (psd) in a region with complex geology and a young and unstable land-surface? The main objective of this study was to answer this question. A set of 339 soil samples from a small slope catchment in Southern Brazil was used to build PMs of psd in the surface soil layer. Multiple linear regression models were constructed using terrain attributes (elevation, slope, catchment area, convergence index, and topographi...

  20. The stickiness of micrometer-sized water-ice particles

    CERN Document Server

    Gundlach, B

    2014-01-01

    Water ice is one of the most abundant materials in dense molecular clouds and in the outer reaches of protoplanetary disks. In contrast to other materials (e.g., silicates) water ice is assumed to be stickier due to its higher specific surface energy, leading to faster or more efficient growth in mutual collisions. However, experiments investigating the stickiness of water ice have been scarce, particularly in the astrophysically relevant micrometer-size region and at low temperatures. In this work, we present an experimental setup to grow aggregates composed of $\\mathrm{\\mu}$m-sized water-ice particles, which we used to measure the sticking and erosion thresholds of the ice particles at different temperatures between $114 \\, \\mathrm{K}$ and $260 \\, \\mathrm{K}$. We show with our experiments that for low temperatures (below $\\sim 210 \\, \\mathrm{K}$), $\\mathrm{\\mu}$m-sized water-ice particles stick below a threshold velocity of $9.6 \\, \\mathrm{m \\, s^{-1}}$, which is approximately ten times higher than the stic...

  1. Production of large-particle-size monodisperse latexes

    Science.gov (United States)

    Vanderhoff, J. W.; El-Aasser, M. L.; Micale, F. J.; Sudol, E. D.; Tseng, C. M.; Silwanowicz, A.

    1984-01-01

    The research program achieved two objectives: (1) it has refined and extended the experimental techniques for preparing monodisperse latexes in quantity on the ground up to a particle diameter of 10 microns; and (2) it has demonstrated that a microgravity environment can be used to grow monodisperse latexes to larger sizes, where the limitations in size have yet to be defined. The experimental development of the monodisperse latex reactor (MLR) and the seeded emulsion polymerizations carried out in the laboratory prototype of the flight hardware, as a function of the operational parameters is discussed. The emphasis is directed towards the measurement, interpretation, and modeling of the kinetics of seeded emulsion polymerization and successive seeded emulsion polymerization. The recipe development of seeded emulsion polymerization as a function of particle size is discussed. The equilibrium swelling of latex particles with monomers was investigated both theoretically and experimentally. Extensive studies are reported on both the type and concentration of initiators, surfactants, and inhibitors, which eventually led to the development of the flight recipes. The experimental results of the flight experiments are discussed, as well as the experimental development of inhibition of seeded emulsion polymerization in terms of time of inhibition and the effect of inhibitors on the kinetics of polymerization.

  2. Effect of proteins, polysaccharides, and particle sizes on sludge dewaterability

    Institute of Scientific and Technical Information of China (English)

    SHAO Liming; HE Peipei; YU Guanghui; HE Pinjing

    2009-01-01

    Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins (PN) and polysaccharides (PS) in the sludge, the PN/PS ratio, the particle sizes, and their relationship with sludge dewaterability (as determined by capillary suction time, CST). The sludge flocs were stratified through centrifugation- and ultrasound-based method into four layers: (1) slime, (2) loosely bound extracellular polymeric substances (LB-EPS), (3) tightly bound EPS (TB-EPS), and (4) pellet. The results showed that PN was mainly partitioned in the pellet (80.7%) and TB-EPS (9.6%) layers, while PS distributed evenly in the four layers. During hydrolysis and acidification, PN was transferred from the pellet and TB-EPS layers to the slime layer, but PS had no significant transfer trends. The mean particle sizes of the sludge flocs decreased with hydrolysis and acidification. The pH had a more significant influence on the dewaterability of sludge flocs than temperature. Sludge dewaterability during hydrolysis and acidification processes greatly deteriorated from 9.7 s at raw sludge to 340--450 s under alkaline conditions. However, it was just slightly increased under acidic conditions. Further investigation suggested that CST was affected by soluble PN, soluble PN/PS, and particle sizes of sludge flocs, but was affected slightly by total PN, PS, or PN/PS in the whole sludge flocs and other layers (except slime).

  3. Particle Size Distribution in Saturn’s Ring C

    Science.gov (United States)

    Marouf, Essam A.; Wong, K.; French, R.; Rappaport, N.

    2012-10-01

    Information about particle sizes in Saturn’s rings is provided by two complementary types of Cassini radio occultation measurements. The first is differential extinction of three coherent sinusoidal signals transmitted by Cassini through the rings back to Earth (wavelength = 0.94, 3.6, and 13 cm, respectively). The differential measurements strongly constraint three parameters of an assumed power-law size distribution n(a) = n0 (a/a0)q, amin ≤ a ≤ amax: namely, the power law index q, the minimum radius amin, and reference abundance n0 at reference radius a0. The differential measurements are particularly sensitive to radii in the range 0.1 mm features of width as small several hundred kilometers can be identified and isolated in the measured spectra for a small subset of Cassini orbits of favorable geometry. We use three inverse scattering algorithms (Bayes, constrained linear inversion, generalized singular-value-decomposition) to recover the size distribution of particles of resolved ring features over the size range 1 m consistency of the results with a single power-law model extending over 0.1 mm selected features across Saturn’s Ring C where little evidence for gravitational wakes is present, hence the approaches above are applicable.

  4. Effect of particle size on degree of inversion in ferrites

    International Nuclear Information System (INIS)

    Ferrites with the spinel structure are important materials because of their structural, magnetic and electrical properties. The suitability of these materials depends on both the intrinsic behavior of the material and the effects of the grain size. Moessbauer spectroscopy was employed to investigate the cation distribution and degree of inversion in bulk and nano sized particles of CuFe/sub 2/O/sub 4/, MnFe/sub 2/O/sub 4/ and NiFe/sub 2/O/sub 4/ ferrites. The Moessbauer spectra of all bulk ferrites showed complete magnetic behavior, whereas nanoparticle ferrites showed combination of ferromagnetic and superparamagnetic components. Moreover, the cation distribution in nanoparticle materials was also found to be different to that of their bulk counterparts indicating the particle size dependency. The inversion of Cu and Ni ions in bulk sample was greater than that of nanoparticles; whereas the inversion of Mn ions was less in bulk material as compared to the nanoparticles. Hence the degree of inversion decreased in CuFe/sub 2/O/sub 4/ and NiFe/sub 2/O/sub 4/ samples whereas, it increased in MnFe/sub 2/O/sub 4/ as the particle size decreased and thus showed the anomalous behavior in this case. The nanoparticle samples also showed paramagnetic behaviour due to superparamagnetism and this effect is more prominent in MnFe/sub 2/O/sub 4/. Moessbauer spectra of bulk and nanoparticles CuFe/sub 2/O/sub 4/ is shown. (Orig./A.B.)

  5. Inverse problem for particle size distributions of atmospheric aerosols using stochastic particle swarm optimization

    International Nuclear Information System (INIS)

    As a part of resolving optical properties in atmosphere radiative transfer calculations, this paper focuses on obtaining aerosol optical thicknesses (AOTs) in the visible and near infrared wave band through indirect method by gleaning the values of aerosol particle size distribution parameters. Although various inverse techniques have been applied to obtain values for these parameters, we choose a stochastic particle swarm optimization (SPSO) algorithm to perform an inverse calculation. Computational performances of different inverse methods are investigated and the influence of swarm size on the inverse problem of computation particles is examined. Next, computational efficiencies of various particle size distributions and the influences of the measured errors on computational accuracy are compared. Finally, we recover particle size distributions for atmospheric aerosols over Beijing using the measured AOT data (at wavelengths λ=0.400, 0.690, 0.870, and 1.020 μm) obtained from AERONET at different times and then calculate other AOT values for this band based on the inverse results. With calculations agreeing with measured data, the SPSO algorithm shows good practicability.

  6. Gas-solute dispersivity ratio in granular porous media as related to particle size distribution and particle shape

    DEFF Research Database (Denmark)

    Pugliese, Lorenzo; Poulsen, Tjalfe; Straface, Salvatore

    2013-01-01

    by fitting the advection-dispersion equation to the measured breakthrough curves and in turn used to calculate gas and solute dispersivities as a function of mean particle size (Dm) and particle size range (R) for the 63 particle size fractions considered. The results show that solute and gas...

  7. Measurements of Nucleation-Mode Particle Size Distributions in Aircraft Plumes during SULFUR 6

    Science.gov (United States)

    Brock, Charles A.; Bradford, Deborah G.

    1999-01-01

    This report summarizes the participation of the University of Denver in an airborne measurement program, SULFUR 6, which was undertaken in late September and early October of 1998 by the Deutsches Zentrum fur Luft und Raumfahrt (DLR). Scientific findings from two papers that have been published or accepted and from one manuscript that is in preparation are presented. The SULFUR 6 experiment was designed to investigate the emissions from subsonic aircraft to constrain calculations of possible atmospheric chemical and climatic effects. The University of Denver effort contributed toward the following SULFUR 6 goals: (1) To investigate the relationship between fuel sulfur content (FSC--mass of sulfur per mass of fuel) and particle number and mass emission index (El--quantity emitted per kg of fuel burned); (2) To provide upper and lower limits for the mass conversion efficiency (nu) of fuel sulfur to gaseous and particulate sulfuric acid; (3) To constrain models of volatile particle nucleation and growth by measuring the particle size distribution between 3 and 100 nm at aircraft plume ages ranging from 10(exp -1) to 10(exp 3) s; (4) To determine microphysical and optical properties and bulk chemical composition of soot particles in aircraft exhaust; and (5) To investigate the differences in particle properties between aircraft plumes in contrail and non-contrail situations. The experiment focused on emissions from the ATTAS research aircraft (a well characterized, but older technology turbojet) and from an in-service Boeing 737-300 aircraft provided by Lufthansa, with modem, high-bypass turbofan engines. Measurements were made from the DLR Dassault Falcon 900 aircraft, a modified business jet. The Atmospheric Effects of Aviation Program (AEAP) provided funding to operate an instrument, the nucleation-mode aerosol size spectrometer (N-MASS), during the SULFUR 6 campaign and to analyze the data. The N-MASS was developed at the University of Denver with the support of

  8. Urban sediment particle size and pollutants in Southern Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Poleto, Cristiano; Merten, Gustavo H. [Federal Univ. of Rio Grande do Sul - UFRGS, Porto Alegre, RS (BR). Hydraulic Research Inst. (IPH); Bortoluzzi, Edson C. [Univ. of Passo Fundo - UPF, RS (Brazil); Charlesworth, Susanne M. [Coventry Univ. (United Kingdom). Dept. of Geography, Environment and Disaster Management

    2009-08-15

    Background, aim and scope: Studies of particulate-associated pollutants, or PAPs, in urban areas have become necessary due to their potentially deleterious effects on the environment. However, it is not just the sediments themselves which are problematic but also their particle size composition, which has a great influence on their capacity to adsorb and transport pollutants. This paper presents the particle size distributions and concentrations of five metals (Cr, Cu, Ni, Pb and Zn) of urban sediments collected from paved streets and gully pots from 20 cities in southern Brazil. The cities have different characteristics and hence sources of PAPs associated with differing geologies, soil types and type of urbanisation. Studies of this nature enable elucidation of the relationship between diffuse sources such as streets and gully pots and the likelihood of PAPs to subsequently pollute the urban aquatic environment. Materials and methods: Sediment samples were taken at random from paved streets and gully pots in 20 cities in Rio Grande do Sul state, southern Brazil by means of a portable vacuum cleaner to avoid loss of finer particles. The particle sizes of the samples were measured using a Cilas {sup registered} 1180 laser particle analyzer, and the concentrations of five metals (Cr, Cu, Ni, Pb and Zn) were determined by wet acid digestion (HCl-HF-HClO{sub 4}-HNO{sub 3}) followed by inductively coupled plasma atomic emission spectroscopy on the <63-{mu}m fraction. Results: It was found that in comparison to sediments collected from the streets, gully pot sediments were more heterogeneous in terms of particle size and also that sediment samples from the gully pots were predominantly coarser than those originating on the streets. From the gully pot results, analysis of the modal particle diameter enabled the cities to be divided into three categories. The concentrations of metals in the street sediments were similar across all 20 cities, with all concentrations above

  9. Chemically generated convective transport of micron sized particles

    Science.gov (United States)

    Shklyaev, Oleg; Das, Sambeeta; Altemose, Alicia; Shum, Henry; Balazs, Anna; Sen, Ayusman

    2015-11-01

    A variety of chemical and biological applications require manipulation of micron sized objects like cells, viruses, and large molecules. Increasing the size of particles up to a micron reduces performance of techniques based on diffusive transport. Directional transport of cargo toward detecting elements reduces the delivery time and improves performance of sensing devices. We demonstrate how chemical reactions can be used to organize fluid flows carrying particles toward the assigned destinations. Convection is driven by density variations caused by a chemical reaction occurring at a catalyst or enzyme-covered target site. If the reaction causes a reduction in fluid density, as in the case of catalytic decomposition of hydrogen peroxide, then fluid and suspended cargo is drawn toward the target along the bottom surface. The intensity of the fluid flow and the time of cargo delivery are controlled by the amount of reagent in the system. After the reagent has been consumed, the fluid pump stops and particles are found aggregated on and around the enzyme-coated patch. The pumps are reusable, being reactivated upon injection of additional reagent. The developed technique can be implemented in lab-on-a-chip devices for transportation of micro-scale object immersed in solution.

  10. Particle size - An important factor in environmental consequence modeling

    International Nuclear Information System (INIS)

    Most available environmental transport and dosimetry codes for radiological consequence analysis are designed primarily for estimating dose and health consequences to specific off-site individuals as well as the population as a whole from nuclear facilities operating under either normal or accident conditions. Models developed for these types of analyses are generally based on assumptions that the receptors are at great distances (several kilometers), and the releases are prolonged and filtered. This allows the use of simplified approaches such as averaged meteorological conditions and the use of a single (small) particle size for atmospheric transport and dosimetry analysis. Source depletion from particle settling, settle-out, and deposition is often ignored. This paper estimates the effects of large particles on the resulting dose consequences from an atmospheric release. The computer program AI-RISK has been developed to perform multiparticle-sized atmospheric transport, dose, and pathway analyses for estimating potential human health consequences from the accidental release of radioactive materials. The program was originally developed to facilitate comprehensive analyses of health consequences, ground contamination, and cleanup associated with possible energetic chemical reactions in high-level radioactive waste (HLW) tanks at a US Department of Energy site

  11. Interpretation of aerosol trace metal particle size distributions

    International Nuclear Information System (INIS)

    Proton-induced X-ray emission (PIXE) analysis is capable of rapid routine determination of 10--15 elements present in amounts greater than or equal to 1 ng simultaneously in aerosol size fractions as collected by single orifice impactors over short periods of time. This enables detailed study of complex relationships between elements detected. Since absolute elemental concentrations may be strongly influenced by meteorological and topographical conditions, it is useful to normalize to a reference element. Comparison between the ratios of concentrations with aerosol and corresponding values for anticipated sources may lead to the identification of important sources for the elements. Further geochemical insights may be found through linear correlation coefficients, regression analysis, and cluster analysis. By calculating correlations for elemental pairs, an indication of the degree of covariance between the elements is obtained. Preliminary results indicate that correlations may be particle size dependent. A high degree of covariance may be caused either by a common source or may only reflect the conservative nature of the aerosol. In a regression analysis, by plotting elemental pairs and estimating the regression coefficients, we may be able to conclude if there is more than one source operating for a given element in a certain size range. Analysis of clustering of several elements, previously investigated for aerosol filter samples, can be applied to the analysis of aerosol size fractions. Careful statistical treatment of elemental concentrations as a function of aerosol particle size may thus yield significant information on the generation, transport and deposition of trace metals in the atmosphere

  12. Building predictive models of soil particle-size distribution

    Directory of Open Access Journals (Sweden)

    Alessandro Samuel-Rosa

    2013-04-01

    Full Text Available Is it possible to build predictive models (PMs of soil particle-size distribution (psd in a region with complex geology and a young and unstable land-surface? The main objective of this study was to answer this question. A set of 339 soil samples from a small slope catchment in Southern Brazil was used to build PMs of psd in the surface soil layer. Multiple linear regression models were constructed using terrain attributes (elevation, slope, catchment area, convergence index, and topographic wetness index. The PMs explained more than half of the data variance. This performance is similar to (or even better than that of the conventional soil mapping approach. For some size fractions, the PM performance can reach 70 %. Largest uncertainties were observed in geologically more complex areas. Therefore, significant improvements in the predictions can only be achieved if accurate geological data is made available. Meanwhile, PMs built on terrain attributes are efficient in predicting the particle-size distribution (psd of soils in regions of complex geology.

  13. Totally asymmetric exclusion processes with particles of arbitrary size

    International Nuclear Information System (INIS)

    The steady-state currents and densities of a one-dimensional totally asymmetric exclusion process (TASEP) with particles that occlude an integer number (d) of lattice sites are computed using various mean-field approximations and Monte Carlo simulations. TASEPs featuring particles of arbitrary size are relevant for modelling systems such as mRNA translation, vesicle locomotion along microtubules and protein sliding along DNA. We conjecture that the nonequilibrium steady-state properties separate into low-density, high-density, and maximal current phases similar to those of the standard (d = 1) TASEP. A simple mean-field approximation for steady-state particle currents and densities is found to be inaccurate. However, we find local equilibrium particle distributions derived from a discrete Tonks gas partition function yield apparently exact currents within the maximal current phase. For the boundary-limited phases, the equilibrium Tonks gas distribution cannot be used to predict currents, phase boundaries, or the order of the phase transitions. However, we employ a refined mean-field approach to find apparently exact expressions for the steady-state currents, boundary densities, and phase diagrams of the d ≥ 1 TASEP. Extensive Monte Carlo simulations are performed to support our analytic, mean-field results

  14. Totally asymmetric exclusion processes with particles of arbitrary size

    Energy Technology Data Exchange (ETDEWEB)

    Lakatos, Greg; Chou, Tom [Department of Biomathematics and Institute for Pure and Applied Mathematics, UCLA, Los Angeles, CA 90095 (United States)

    2003-02-28

    The steady-state currents and densities of a one-dimensional totally asymmetric exclusion process (TASEP) with particles that occlude an integer number (d) of lattice sites are computed using various mean-field approximations and Monte Carlo simulations. TASEPs featuring particles of arbitrary size are relevant for modelling systems such as mRNA translation, vesicle locomotion along microtubules and protein sliding along DNA. We conjecture that the nonequilibrium steady-state properties separate into low-density, high-density, and maximal current phases similar to those of the standard (d = 1) TASEP. A simple mean-field approximation for steady-state particle currents and densities is found to be inaccurate. However, we find local equilibrium particle distributions derived from a discrete Tonks gas partition function yield apparently exact currents within the maximal current phase. For the boundary-limited phases, the equilibrium Tonks gas distribution cannot be used to predict currents, phase boundaries, or the order of the phase transitions. However, we employ a refined mean-field approach to find apparently exact expressions for the steady-state currents, boundary densities, and phase diagrams of the d {>=} 1 TASEP. Extensive Monte Carlo simulations are performed to support our analytic, mean-field results.

  15. Influence of Particle Size on Properties of Expanded Graphite

    Directory of Open Access Journals (Sweden)

    Kurajica, S

    2010-02-01

    Full Text Available Expanded graphite has been applied widely in thermal insulation, adsorption, vibration damping, gasketing, electromagnetic interference shielding etc. It is made by intercalation of natural flake graphite followed by thermal expansion. Intercalation is a process whereby an intercalant material is inserted between the graphene layers of a graphite crystal. Exfoliation, a huge unidirectional expansion of the starting intercalated flakes, occurs when the graphene layers are forced apart by the sudden decomposition and vaporization of the intercalated species by thermal shock. Along with production methodologies, such as the intercalation process and heat treatment, the raw material characteristics, especially particle size, strongly influence the properties of the final product.This report evaluates the influence of the particle size of the raw material on the intercalation and expansion processes and consequently the properties of the exfoliated graphite. Natural crystalline flake graphite with wide particle diameter distribution (between dp = 80 and 425 µm was divided into four size-range portions by sieving. Graphite was intercalated via perchloric acid, glacial acetic acid and potassium dichromate oxidation and intercalation procedure. 5.0 g of graphite, 7.0 g of perchloric acid, 4.0 g of glacial acetic acid and 2.0 g of potassium dichromate were placed in glass reactor. The mixture was stirred with n = 200 min–1 at temperature of 45 °C during 60 min. Then it was filtered and washed with distilled water until pH~6 and dried at 60 °C during 24 h. Expansion was accomplished by thermal shock at 1000 °C for 1 min. The prepared samples were characterized by means of exfoliation volume measurements, simultaneous differential thermal analysis and thermo-gravimetry (DTA/TGA, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, BET measurements and scanning electron microscopy (SEM.X-ray diffraction indicated a change of distance

  16. Effects of particle size on the mechanical properties of particle-reinforced Sn-Ag composite solder joint

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Particulate size has significant influenced on the mechanical properties of particle-reinforced composite solder joints. In this current research, Cu or Ni reinforcement particles were mechanically added to the Sn-3.5Ag eutectic solder, and the effects of the particle size on the mechanical properties of particle-reinforced composite solder joint were systematically studied. This investigation touched on how mechanical properties of the solder joints are affected by particles size. A quantitative formula was set up to correlate the mechanical property of the solder joint with particle size in different processing conditions. Besides, the fracture mechanism of the composite solder joint was analyzed.

  17. Dynamics of a system of sticking particles of a finite size on the line

    OpenAIRE

    Wolansky, Gershon

    2006-01-01

    The continuous limit of large systems of particles of finite size on the line is described. The particles are assumed to move freely and stick under collision, to form compound particles whose mass and size is the sum of the masses and sizes of the particles before collision, and whose velocity is determined by conservation of linear momentum.

  18. Particle size tuning in silver-polyacrylonitrile nanocomposites

    Directory of Open Access Journals (Sweden)

    2010-02-01

    Full Text Available Silver-polyacrylonitrile (Ag-PAN nanocomposites were in situ synthesized by simultaneous polymerization of acrylonitrile and reduction of silver ions, starting from mixtures of silver nitrate (AgNO3, acrylonitrile (AN, and UV photoinitiator (IN. The films obtained proved to be transparent and were characterized by a homogeneous dispersion of Ag nanoparticles within the PAN matrix without any macroscopic agglomeration. The particle size and number density were found to depend on both precursor salt and UV photoinitiator weight percentages. Optical and electrical properties were investigated as a function of both AgNO3 and IN amounts, too. We found that it is possible to finely tailor the metal nanoparticle size and number density and, consequently, the film optical and electrical response by adjusting the amounts of precursor salt and UV photoinitiator in the initial mixtures.

  19. Isotope ratio analysis on micron-sized particles in complex matrices by Laser Ablation-Absorption Ratio Spectrometry

    International Nuclear Information System (INIS)

    Laser ablation has been combined with dual tunable diode laser absorption spectrometry to measure 152Gd:160Gd isotope ratios in micron-size particles. The diode lasers are tuned to specific isotopes in two different atomic transitions at 405.9 nm (152Gd) and 413.4 nm (160Gd) and directed collinearly through the laser ablation plume, separated on a diffraction grating, and detected with photodiodes to monitor transient absorption signals on a shot-by-shot basis. The method has been characterized first using Gd metal foil and then with particles of GdCl3.xH20 as binary and ternary mixtures with 152Gd:160Gd isotope ratios ranging from 0.01 to 0.43. These particulate mixtures have been diluted with Columbia River sediment powder (SRM 4350B) to simulate environmental samples and we show the method is capable of detecting a few highly-enriched particles in the presence of a >100-fold excess of low-enrichment particles, even when the Gd-bearing particles are a minor component (0.08%) in the SRM powder and widely dispersed (1178 particles detected in 800,000 ablation laser shots). The implications for monitoring 235U:238U enrichment ratios in airborne particle samples, as related to the nuclear industry, are discussed.

  20. Size Resolved High Temperature Oxidation Kinetics of Nano-Sized Titanium and Zirconium Particles.

    Science.gov (United States)

    Zong, Yichen; Jacob, Rohit J; Li, Shuiqing; Zachariah, Michael R

    2015-06-18

    While ultrafine metal particles offer the possibility of very high energy density fuels, there is considerable uncertainty in the mechanism by which metal nanoparticles burn, and few studies that have examined the size dependence to their kinetics at the nanoscale. In this work we quantify the size dependence to the burning rate of titanium and zirconium nanoparticles. Nanoparticles in the range of 20-150 nm were produced via pulsed laser ablation, and then in-flight size-selected using differential electrical mobility. The size-selected oxide free metal particles were directly injected into the post flame region of a laminar flame to create a high temperature (1700-2500 K) oxidizing environment. The reaction was monitored using high-speed videography by tracking the emission from individual nanoparticles. We find that sintering occurs prior to significant reaction, and that once sintering is accounted for, the rate of combustion follows a near nearly (diameter)(1) power-law dependence. Additionally, Arrhenius parameters for the combustion of these nanoparticles were evaluated by measuring the burn times at different ambient temperatures. The optical emission from combustion was also used to model the oxidation process, which we find can be reasonably described with a kinetically controlled shrinking core model. PMID:25914926

  1. Experimental investigation of suspended particles transport through porous media: particle and grain size effect.

    Science.gov (United States)

    Liu, Quansheng; Cui, Xianze; Zhang, Chengyuan; Huang, Shibing

    2016-01-01

    Particle and grain size may influence the transportation and deposition characteristics of particles within pollutant transport and within granular filters that are typically used in wastewater treatment. We conducted two-dimensional sandbox experiments using quartz powder as the particles and quartz sand as the porous medium to study the response of transportation and deposition formation to changes in particle diameter (ds, with median diameter 18, 41, and 82 μm) and grain diameter (dp, with median diameter 0.36, 1.25, and 2.82 mm) considering a wide range of diameter ratios (ds/dp) from 0.0064 to 0.228. Particles were suspended in deionized water, and quartz sand was used as the porous medium, which was meticulously cleaned to minimize any physicochemical and impurities effects that could result in indeterminate results. After the experiments, the particle concentration of the effluent and particle mass per gram of dry sands were measured to explore changes in transportation and deposition characteristics under different conditions. In addition, a micro-analysis was conducted to better analyse the results on a mesoscopic scale. The experimental observation analyses indicate that different diameter ratios (ds/dp) may lead to different deposit formations. As ds/dp increased, the deposit formation changed from 'Random Deposition Type' to 'Gradient Deposition Type', and eventually became 'Inlet Deposition Type'. PMID:26323505

  2. Toxic effects of indoor and outdoor airborne particles relevant to carcinogenesis.

    NARCIS (Netherlands)

    Heussen, G.A.H.

    1993-01-01

    The mutagenicity of indoor and outdoor airborne particulate matter (APM) has been demonstrated by previous in vitro studies (Alink et al., 1983; Van Houdt et al., 1984, 1986, 1987). The aim of the present thesis was to contribute to a better understanding of the mode of action of AIM in the pathogen

  3. Performance of a scanning mobility particle sizer in measuring diverse types of airborne nanoparticles: Multi-walled carbon nanotubes, welding fumes, and titanium dioxide spray.

    Science.gov (United States)

    Chen, Bean T; Schwegler-Berry, Diane; Cumpston, Amy; Cumpston, Jared; Friend, Sherri; Stone, Samuel; Keane, Michael

    2016-07-01

    Direct-reading instruments have been widely used for characterizing airborne nanoparticles in inhalation toxicology and industrial hygiene studies for exposure/risk assessments. Instruments using electrical mobility sizing followed by optical counting, e.g., scanning or sequential mobility particle spectrometers (SMPS), have been considered as the "gold standard" for characterizing nanoparticles. An SMPS has the advantage of rapid response and has been widely used, but there is little information on its performance in assessing the full spectrum of nanoparticles encountered in the workplace. In this study, an SMPS was evaluated for its effectiveness in producing "monodisperse" aerosol and its adequacy in characterizing overall particle size distribution using three test aerosols, each mimicking a unique class of real-life nanoparticles: singlets of nearly spherical titanium dioxide (TiO2), agglomerates of fiber-like multi-walled carbon nanotube (MWCNT), and aggregates that constitutes welding fume (WF). These aerosols were analyzed by SMPS, cascade impactor, and by counting and sizing of discrete particles by scanning and transmission electron microscopy. The effectiveness of the SMPS to produce classified particles (fixed voltage mode) was assessed by examination of the resulting geometric standard deviation (GSD) from the impactor measurement. Results indicated that SMPS performed reasonably well for TiO2 (GSD = 1.3), but not for MWCNT and WF as evidenced by the large GSD values of 1.8 and 1.5, respectively. For overall characterization, results from SMPS (scanning voltage mode) exhibited particle-dependent discrepancies in the size distribution and total number concentration compared to those from microscopic analysis. Further investigation showed that use of a single-stage impactor at the SMPS inlet could distort the size distribution and underestimate the concentration as shown by the SMPS, whereas the presence of vapor molecules or atom clusters in some test

  4. Performance of a Scanning Mobility Particle Sizer in Measuring Diverse Types of Airborne Nanoparticles: Multi-Walled Carbon Nanotubes, Welding Fumes, and Titanium Dioxide Spray

    Science.gov (United States)

    Chen, Bean T.; Schwegler-Berry, Diane; Cumpston, Amy; Cumpston, Jared; Friend, Sherri; Stone, Samuel; Keane, Michael

    2016-01-01

    Direct-reading instruments have been widely used for characterizing airborne nanoparticles in inhalation toxicology and industrial hygiene studies for exposure/risk assessments. Instruments using electrical mobility sizing followed by optical counting, e.g., scanning or sequential mobility particle spectrometers (SMPS), have been considered as the “gold standard” for characterizing nanoparticles. An SMPS has the advantage of rapid response and has been widely used, but there is little information on its performance in assessing the full spectrum of nanoparticles encountered in the workplace. In this study, an SMPS was evaluated for its effectiveness in producing “monodisperse” aerosol and its adequacy in characterizing overall particle size distribution using three test aerosols, each mimicking a unique class of real-life nanoparticles: singlets of nearly spherical titanium dioxide (TiO2), agglomerates of fiber-like multi-walled carbon nanotube (MWCNT), and aggregates that constitutes welding fume (WF). These aerosols were analyzed by SMPS, cascade impactor, and by counting and sizing of discrete particles by scanning and transmission electron microscopy. The effectiveness of the SMPS to produce classified particles (fixed voltage mode) was assessed by examination of the resulting geometric standard deviation (GSD) from the impactor measurement. Results indicated that SMPS performed reasonably well for TiO2 (GSD = 1.3), but not for MWCNT and WF as evidenced by the large GSD values of 1.8 and 1.5, respectively. For overall characterization, results from SMPS (scanning voltage mode) exhibited particle-dependent discrepancies in the size distribution and total number concentration compared to those from microscopic analysis. Further investigation showed that use of a single-stage impactor at the SMPS inlet could distort the size distribution and underestimate the concentration as shown by the SMPS, whereas the presence of vapor molecules or atom clusters in

  5. Effects of particle size on the mechanical properties of particle-reinforced Sn-Ag composite solder joint

    Institute of Scientific and Technical Information of China (English)

    TAI Feng; GUO Fu

    2009-01-01

    Particulate size has significant influenced on the mechanical properties of particle-reinforced compos-ite solder joints. In this current research, Cu or Ni reinforcement particles were mechanically added to the Sn-3.5Ag eutectic solder, and the effects of the particle size on the mechanical properties of parti-cle-reinforced composite solder joint were systematically studied. This investigation touched on how mechanical properties of the solder joints are affected by particles size. A quantitative formula was set up to correlate the mechanical property of the solder joint with particle size in different processing conditions. Besides, the fracture mechanism of the composite solder joint was analyzed.

  6. Size distribution of radon daughter particles in uranium mine atmospheres

    International Nuclear Information System (INIS)

    An investigation of the particle size distribution and other properties of radon daughters in uranium mines was reported earlier but only summaries of the data were presented. This report consists mainly of tables of detailed measurements that were omitted in the original article. The tabulated data include the size distributions, uncombined fractions and ratios of radon daughters as well as the working levels, radon concentrations, condensation nuclei concentrations, temperature, and relative humidity. The measurements were made in 27 locations in four large underground mines in New Mexico during typical mining operations. The size distributions of the radon daughters were log normal. The activity median diameters ranged from 0.09 μm to 0.3 μm with a mean of 0.17 μm. Geometric standard deviations were from 1.3 to 4 with a mean of 2.7. Uncombined fractions expressed in accordance with the ICRP definition ranged from 0.004 to 0.16 with a mean of 0.04

  7. Particle size effect on velocity of gold particle embedded laser driven plastic targets

    International Nuclear Information System (INIS)

    A scheme to enhance the target foil velocity has been investigated for a direct drive inertial fusion target. Polymer PVA (polyvinyl alcohol or (C2H4O)n) target foils of thickness 15-20 μm were used in plain form and also embedded with gold in the nano-particle (Au-np) or micro-particle (Au-mp) form. Nano-particles were of 20-50 nm and micro-particles of 2-3 μm in size. 17% higher target velocity was measured for foils embedded with nano-particle gold (Au-np) as compared to targets embedded with micro-particles gold (Au-mp). The weight of gold in both cases was in the range 40-55% of the full target weight (atomic percentage of about 22%). Experiments were performed with the single beam of the Prague Asterix Laser System (PALS) at 0.43 μm wavelength (3ω of the fundamental wavelength), 120 Joule energy and 300 psec pulse duration. Laser intensity on the target was about 1015 W/cm2. A simple model has been proposed to explain the experimental results. (authors)

  8. Micro-sized and Nano-sized Fe3O4 Particles as Anode Materials for Lithium-ion Batteries

    Institute of Scientific and Technical Information of China (English)

    Y.X.Chen; L.H.He; P.J.Shang; Q.L.Tang; Z.Q.Liu; H.B.Liu; L.P.Zhou

    2011-01-01

    Micro-sized (1030.3±178.4 nm) and nano-sized (50.4±8.0 nm) Fe3O4 particles have been fabricated through hydrogen thermal reduction of α-Fe2O3 particles synthesized by means of a hydrothermal process. The morphology and microstructure of the micro-sized and the nano-sized Fe3O4 particles were characterized by X-ray diffraction, field-emission gun scanning electron microscopy, transmission electron microscopy and highresolution electron microscopy. The micro-sized Fe3O4 particles exhibit porous structure, while the nano-sized Fe3O4 particles are solid structure. Their electrochemical performance was also evaluated. The nano-sized solid Fe3O4 particles exhibit gradual capacity fading with initial discharge capacity of 1083.1 mAhg-1 and reversible capacity retention of 32.6% over 50 cycles. Interestingly, the micro-sized porous Fe3O4 particles display very stable capacity-cycling behavior, with initial discharge capacity of 887.5 mAhg-1 and charge capacity of 684.4 mAhg-1 at the 50th cycle. Therefore, 77.1% of the reversible capacity can be maintained over 50 cycles. The micro-sized porous Fe3O4 particles with facile synthesis, good cycling performance and high capacity retention are promising candidate as anode materials for high energy-density lithium-ion batteries.

  9. Airborne Biogenic Particles in the Snow of the Cities of the Russian Far East as Potential Allergic Compounds

    Directory of Open Access Journals (Sweden)

    Kirill S. Golokhvast

    2014-01-01

    Full Text Available This paper presents an analysis of airborne biogenic particles (1 mkm–1 mm found in the snow in several cities of the Russian Far East during 2010–2013. The most common was vegetational terraneous detritus (fragments of tree and grass leaves followed by animal hair, small insects and their fragments, microorganisms of aeroplankton, and equivocal biological garbage. Specific components were found in samples from locations close to bodies of water such as fragments of algae and mollusc shells and, marine invertebrates (needles of sea urchins and shell debris of arthropods. In most locations across the Far East (Vladivostok, Khabarovsk, Blagoveshchensk, and Ussuriysk, the content of biogenic particles collected in the winter did not exceed 10% of the total particulate matter, with the exception of Birobidzhan and the nature reserve Bastak, where it made up to 20%. Most of all biogenic compounds should be allergic: hair, fragments of tree and grass leaves, insects, and microorganisms.

  10. Airborne biogenic particles in the snow of the cities of the Russian Far East as potential allergic compounds.

    Science.gov (United States)

    Golokhvast, Kirill S

    2014-01-01

    This paper presents an analysis of airborne biogenic particles (1 mkm-1 mm) found in the snow in several cities of the Russian Far East during 2010-2013. The most common was vegetational terraneous detritus (fragments of tree and grass leaves) followed by animal hair, small insects and their fragments, microorganisms of aeroplankton, and equivocal biological garbage. Specific components were found in samples from locations close to bodies of water such as fragments of algae and mollusc shells and, marine invertebrates (needles of sea urchins and shell debris of arthropods). In most locations across the Far East (Vladivostok, Khabarovsk, Blagoveshchensk, and Ussuriysk), the content of biogenic particles collected in the winter did not exceed 10% of the total particulate matter, with the exception of Birobidzhan and the nature reserve Bastak, where it made up to 20%. Most of all biogenic compounds should be allergic: hair, fragments of tree and grass leaves, insects, and microorganisms. PMID:25140327

  11. Strategies for minimizing sample size for use in airborne LiDAR-based forest inventory

    Science.gov (United States)

    Junttila, Virpi; Finley, Andrew O.; Bradford, John B.; Kauranne, Tuomo

    2013-01-01

    Recently airborne Light Detection And Ranging (LiDAR) has emerged as a highly accurate remote sensing modality to be used in operational scale forest inventories. Inventories conducted with the help of LiDAR are most often model-based, i.e. they use variables derived from LiDAR point clouds as the predictive variables that are to be calibrated using field plots. The measurement of the necessary field plots is a time-consuming and statistically sensitive process. Because of this, current practice often presumes hundreds of plots to be collected. But since these plots are only used to calibrate regression models, it should be possible to minimize the number of plots needed by carefully selecting the plots to be measured. In the current study, we compare several systematic and random methods for calibration plot selection, with the specific aim that they be used in LiDAR based regression models for forest parameters, especially above-ground biomass. The primary criteria compared are based on both spatial representativity as well as on their coverage of the variability of the forest features measured. In the former case, it is important also to take into account spatial auto-correlation between the plots. The results indicate that choosing the plots in a way that ensures ample coverage of both spatial and feature space variability improves the performance of the corresponding models, and that adequate coverage of the variability in the feature space is the most important condition that should be met by the set of plots collected.

  12. Measurement of Size-dependent Dynamic Shape Factors of Quartz Particles in Two Flow Regimes

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Jennifer M.; Bell, David M.; Imre, D.; Kleiber, Paul; Grassian, Vicki H.; Zelenyuk, Alla

    2016-08-02

    Understanding and modeling the behavior of quartz dust particles, commonly found in the atmosphere, requires knowledge of many relevant particles properties, including particle shape. This study uses a single particle mass spectrometer, a differential mobility analyzer, and an aerosol particle mass analyzer to measure quartz aerosol particles mobility, aerodynamic, and volume equivalent diameters, mass, composition, effective density, and dynamic shape factor as a function of particle size, in both the free molecular and transition flow regimes. The results clearly demonstrate that dynamic shape factors can vary significantly as a function of particle size. For the quartz samples studied here, the dynamic shape factors increase with size, indicating that larger particles are significantly more aspherical than smaller particles. In addition, dynamic shape factors measured in the free-molecular (χv) and transition (χt) flow regimes can be significantly different, and these differences vary with the size of the quartz particles. For quartz, χv of small (d < 200 nm) particles is 1.25, while χv of larger particles (d ~ 440 nm) is 1.6, with a continuously increasing trend with particle size. In contrast χt, of small particles starts at 1.1 increasing slowly to 1.34 for 550 nm diameter particles. The multidimensional particle characterization approach used here goes beyond determination of average properties for each size, to provide additional information about how the particle dynamic shape factor may vary even for particles with the same mass and volume equivalent diameter.

  13. Mixtures of organic and inorganic substrates, particle size and proportion.

    Directory of Open Access Journals (Sweden)

    Emilio Raymundo Morales-Maldonado

    2015-06-01

    Full Text Available The objective of this paper was to review the mixtures of organic and inorganic materials used in the preparation of a new material, particle size, proportion, and their response in plant. In Mexico, agricultural waste is considered as a pollutant reservoir; however, from another perspective, this represents an industry with great potential. The nutrients ingested by animals represent nutriments available for plants when properly recycled. An option that minimizes the risk of contamination and improves its quality is the production of compost and vermicompost. Both processes are an alternative to organic production. A material by itself does not meet the optimum conditions. Reducing the volume of an organic material increases compaction and compression of roots, affecting the efficiency of irrigation and fertilization, so it is necessary to make mixtures with inorganic materials, that is used in the development of a new material for better growing conditions of the plant.

  14. Drilling coal seam outbursts where particle size matters

    Energy Technology Data Exchange (ETDEWEB)

    Gray, I. [Sigra Pty Ltd. (Australia)

    2009-10-01

    The paper is distilled from the ACARP report 'Coal mine outburst mechanisms, thresholds and predication techniques' originally written in 2006 and added to from recent direct experience of outburst conditions in Central Asian Mines. In an endeavour to provide a basis of prediction as to whether an outburst will occur it takes the approach of examining the total energy that may be released in an outburst. The sources of energy considered are the strain energy that may be released in failure of the coal and in the release of gas. Two modes of gas release are considered, one from pore space and one from diffusion. In the latter case a new model is developed to describe the potential energy release from diffusing particles. In the Australian context it is considered that the elements of energy release due to gas dominate. The critical factors that contributing to energy release in an outburst are: gas content/gas pressure; diffusion coefficient; sorption isotherm; particle size. The less critical factors are: free pore space; stress; and stiffness. 1 ref., 2 figs.

  15. Estimation of Particle Size Distribution and Aspect Ratio of Non-Spherical Particles From Chord Length Distribution

    CERN Document Server

    Agimelen, Okpeafoh S; Vasile, Massimiliano; Nordon, Alison; Haley, Ian; Mulholland, Anthony J

    2014-01-01

    Information about size and shape of particles produced in various manufacturing processes is very important for process and product development because design of downstream processes as well as final product properties strongly depend on these geometrical particle attributes. However, recovery of particle size and shape information in situ during crystallisation processes has been a major challenge. The focused beam reflectance measurement (FBRM) provides the chord length distribution (CLD) of a population of particles in a suspension flowing close to the sensor window. Recovery of size and shape information from the CLD requires a model relating particle size and shape to its CLD as well as solving the corresponding inverse problem. This paper presents a comprehensive algorithm which produces estimates of particle size distribution and particle aspect ratio from measured CLD data. While the algorithm searches for a global best solution to the inverse problem without requiring further a priori information on ...

  16. Shape and Size from the Mist:A Deformable Model for Particle Characterization

    OpenAIRE

    Dahl, Anders Lindbjerg; Jørgensen, Thomas Martini; Gundu, Phanindra Narayan; Larsen, Rasmus

    2010-01-01

    Process optimization often depends on the correct estimation of particle size, their shape and their concentration. In case of the backlight microscopic system, which we investigate here, particle images suffer from out-of-focus blur. This gives a bias towards overestimating the particle size when particles are behind or in front of the focus plane. In most applications only in-focus particles get analyzed, but this weakens the statistical basis and requires either particle sampling over long...

  17. Ultrafine particle size as a tracer for aircraft turbine emissions

    Science.gov (United States)

    Riley, Erin A.; Gould, Timothy; Hartin, Kris; Fruin, Scott A.; Simpson, Christopher D.; Yost, Michael G.; Larson, Timothy

    2016-08-01

    Ultrafine particle number (UFPN) and size distributions, black carbon, and nitrogen dioxide concentrations were measured downwind of two of the busiest airports in the world, Los Angeles International Airport (LAX) and Hartsfield-Jackson International Airport (ATL - Atlanta, GA) using a mobile monitoring platform. Transects were located between 5 km and 10 km from the ATL and LAX airports. In addition, measurements were taken at 43 additional urban neighborhood locations in each city and on freeways. We found a 3-5 fold increase in UFPN concentrations in transects under the landing approach path to both airports relative to surrounding urban areas with similar ground traffic characteristics. The latter UFPN concentrations measured were distinct in size distributional properties from both freeways and across urban neighborhoods, clearly indicating different sources. Elevated concentrations of Black Carbon (BC) and NO2 were also observed on airport transects, and the corresponding pattern of elevated BC was consistent with the observed excess UFPN concentrations relative to other urban locations.

  18. Effect of varying total mixed ration particle size on rumen digesta and fecal particle size and digestibility in lactating dairy cows.

    Science.gov (United States)

    Maulfair, D D; Fustini, M; Heinrichs, A J

    2011-07-01

    The objective of this experiment was to evaluate the effects of feeding rations of different particle sizes on rumen digesta and fecal matter particle size. Four rumen-cannulated, multiparous, Holstein cows (104±15 d in milk) were randomly assigned to treatments in a 4×4 Latin square design. The diets consisted of 29.4% corn silage, 22.9% ground corn, 17.6% alfalfa haylage, and 11.8% dry grass hay [20% of forage dry matter (DM)] on a DM basis. Dry grass hay was chopped to 4 different lengths to vary the total mixed ration (TMR) particle size. Geometric mean particle sizes of the rations were 4.46, 5.10, 5.32, and 5.84 mm for short, medium, long, and extra long diets, respectively. The ration affected rumen digesta particle size for particles ≥3.35 mm, and had no effect on distribution of particles 1.18 mm had ration by time interactions. Fecal neutral detergent fiber (NDF) and indigestible NDF concentrations decreased with increasing TMR particle size. Fecal particle size expressed as total geometric mean particle length followed this same tendency. Fecal particle size, expressed as retained geometric mean particle length, averaged 1.13 mm with more than 36% of particles being larger than 1.18 mm. All fecal nutrient concentrations measured were significantly affected by time after feeding, with NDF and indigestible NDF increasing after feeding and peaking at about 12h later and then decreasing to preprandial levels. Starch concentrations were determined to have the opposite effect. Additionally, apparent digestibility of diet nutrients was analyzed and DM digestibility tended to decrease with increasing TMR particle size, whereas other nutrient digestibilities were not different among rations. These results show that the critical size for increased resistance to rumen escape is larger than 1.18 mm and this critical size is constant throughout the day. This study also concludes that, when using average quality grass hay to provide the range of particle sizes fed

  19. Note: Evaluation of slurry particle size analyzers for chemical mechanical planarization process

    Science.gov (United States)

    Jang, Sunjae; Kulkarni, Atul; Qin, Hongyi; Kim, Taesung

    2016-04-01

    In the chemical mechanical planarization (CMP) process, slurry particle size is important because large particles can cause defects. Hence, selection of an appropriate particle measuring system is necessary in the CMP process. In this study, a scanning mobility particle sizer (SMPS) and dynamic light scattering (DLS) were compared for particle size distribution (PSD) measurements. In addition, the actual particle size and shape were confirmed by transmission electron microscope (TEM) results. SMPS classifies the particle size according to the electrical mobility, and measures the particle concentration (single particle measurement). On the other hand, the DLS measures the particle size distribution by analyzing scattered light from multiple particles (multiple particle measurement). For the slurry particles selected for evaluation, it is observed that SMPS shows bi-modal particle sizes 30 nm and 80 nm, which closely matches with the TEM measurements, whereas DLS shows only single mode distribution in the range of 90 nm to 100 nm and showing incapability of measuring small particles. Hence, SMPS can be a better choice for the evaluation of CMP slurry particle size and concentration measurements.

  20. Carbon-based phytoplankton size classes retrieved via ocean color estimates of the particle size distribution

    Science.gov (United States)

    Kostadinov, Tihomir S.; Milutinović, Svetlana; Marinov, Irina; Cabré, Anna

    2016-04-01

    Owing to their important roles in biogeochemical cycles, phytoplankton functional types (PFTs) have been the aim of an increasing number of ocean color algorithms. Yet, none of the existing methods are based on phytoplankton carbon (C) biomass, which is a fundamental biogeochemical and ecological variable and the "unit of accounting" in Earth system models. We present a novel bio-optical algorithm to retrieve size-partitioned phytoplankton carbon from ocean color satellite data. The algorithm is based on existing methods to estimate particle volume from a power-law particle size distribution (PSD). Volume is converted to carbon concentrations using a compilation of allometric relationships. We quantify absolute and fractional biomass in three PFTs based on size - picophytoplankton (0.5-2 µm in diameter), nanophytoplankton (2-20 µm) and microphytoplankton (20-50 µm). The mean spatial distributions of total phytoplankton C biomass and individual PFTs, derived from global SeaWiFS monthly ocean color data, are consistent with current understanding of oceanic ecosystems, i.e., oligotrophic regions are characterized by low biomass and dominance of picoplankton, whereas eutrophic regions have high biomass to which nanoplankton and microplankton contribute relatively larger fractions. Global climatological, spatially integrated phytoplankton carbon biomass standing stock estimates using our PSD-based approach yield ˜ 0.25 Gt of C, consistent with analogous estimates from two other ocean color algorithms and several state-of-the-art Earth system models. Satisfactory in situ closure observed between PSD and POC measurements lends support to the theoretical basis of the PSD-based algorithm. Uncertainty budget analyses indicate that absolute carbon concentration uncertainties are driven by the PSD parameter No which determines particle number concentration to first order, while uncertainties in PFTs' fractional contributions to total C biomass are mostly due to the

  1. Particle capture by aquatic vegetation modeled in flume experiments: the effects of particle size, stem density, biofilm, and flow velocity

    Science.gov (United States)

    Kerwin, R.; Fauria, K.; Nover, D.; Schladow, G.

    2014-12-01

    Vegetated floodplains and wetlands can trap and remove particles from suspension thereby affecting water quality, land accretion, and wetland functioning. However, the rate of particle removal by vegetation remains poorly characterized, especially for fine particles. In this study, we monitored particle concentration and size distribution (1.25 - 250 µm diameter suspended road dust) in a laboratory flume as flow velocity, plant stem density, initial particle concentration, and the presence of biofilm on vegetation were varied. We characterized change in particle concentration through time by calculating decay constants, termed capture rates. Based on our experiments, we found that suspended particle concentration decayed more rapidly in the presence, rather than in the absence, of vegetation. Additionally, particle capture rates increased with stem density, particle size, and the presence of biofilm, while decreasing with flow velocity. These results demonstrate that low flow velocities and the presence of biofilm optimize particle capture by vegetation. Our results are relevant to floodplain and wetland restoration efforts.

  2. Accumulation and transport of microbial-size particles in a pressure protected model burn unit: CFD simulations and experimental evidence

    Directory of Open Access Journals (Sweden)

    Mimoun Maurice

    2011-03-01

    Full Text Available Abstract Background Controlling airborne contamination is of major importance in burn units because of the high susceptibility of burned patients to infections and the unique environmental conditions that can accentuate the infection risk. In particular the required elevated temperatures in the patient room can create thermal convection flows which can transport airborne contaminates throughout the unit. In order to estimate this risk and optimize the design of an intensive care room intended to host severely burned patients, we have relied on a computational fluid dynamic methodology (CFD. Methods The study was carried out in 4 steps: i patient room design, ii CFD simulations of patient room design to model air flows throughout the patient room, adjacent anterooms and the corridor, iii construction of a prototype room and subsequent experimental studies to characterize its performance iv qualitative comparison of the tendencies between CFD prediction and experimental results. The Electricité De France (EDF open-source software Code_Saturne® (http://www.code-saturne.org was used and CFD simulations were conducted with an hexahedral mesh containing about 300 000 computational cells. The computational domain included the treatment room and two anterooms including equipment, staff and patient. Experiments with inert aerosol particles followed by time-resolved particle counting were conducted in the prototype room for comparison with the CFD observations. Results We found that thermal convection can create contaminated zones near the ceiling of the room, which can subsequently lead to contaminate transfer in adjacent rooms. Experimental confirmation of these phenomena agreed well with CFD predictions and showed that particles greater than one micron (i.e. bacterial or fungal spore sizes can be influenced by these thermally induced flows. When the temperature difference between rooms was 7°C, a significant contamination transfer was observed to

  3. Algorithm of Data Reduce in Determination of Aerosol Particle Size Distribution at Damps/C

    International Nuclear Information System (INIS)

    The analysis had to do for algorithm of data reduction on Damps/C (Differential Mobility Particle Sizer with Condensation Particle Counter) system, this is for determine aerosol particle size distribution with range 0,01 μm to 1 μm in diameter. Damps/C (Differential Mobility Particle Sizer with Condensation Particle Counter) system contents are software and hardware. The hardware used determine of mobilities of aerosol particle and so the software used determine aerosol particle size distribution in diameter. The mobilities and diameter particle had connection in the electricity field. That is basic program for reduction of data and particle size conversion from particle mobility become particle diameter. The analysis to get transfer function value, Ω, is 0.5. The data reduction program to do conversation mobility basis become diameter basis with number efficiency correction, transfer function value, and poly charge particle. (author)

  4. Effect of four different size reduction methods on the particle size, solubility enhancement and physical stability of nicergoline nanocrystals.

    Science.gov (United States)

    Martena, Valentina; Shegokar, Ranjita; Di Martino, Piera; Müller, Rainer H

    2014-09-01

    Nicergoline, a poorly soluble active pharmaceutical ingredient, possesses vaso-active properties which causes peripheral and central vasodilatation. In this study, nanocrystals of nicergoline were prepared in an aqueous solution of polysorbate 80 (nanosuspension) by using four different laboratory scale size reduction techniques: high pressure homogenization (HPH), bead milling (BM) and combination techniques (high pressure homogenization followed by bead milling HPH + BM, and bead milling followed by high pressure homogenization BM + HPH). Nanocrystals were investigated regarding to their mean particles size, zeta potential and particle dissolution. A short term physical stability study on nanocrystals stored at three different temperatures (4, 20 and 40 °C) was performed to evaluate the tendency to change in particle size, aggregation and zeta potential. The size reduction technique and the process parameters like milling time, number of homogenization cycles and pressure greatly affected the size of nanocrystals. Among the techniques used, the combination techniques showed superior and consistent particle size reduction compared to the other two methods, HPH + BM and BM + HPH giving nanocrystals of a mean particle size of 260 and 353 nm, respectively. The particle dissolution was increased for any nanocrystals samples, but it was particularly increased by HPH and combination techniques. Independently to the production method, nicergoline nanocrystals showed slight increase in particle size over the time, but remained below 500 nm at 20 °C and refrigeration conditions. PMID:23815299

  5. Characterization of airborne uranium from test firing of XM774 ammunition

    International Nuclear Information System (INIS)

    Pacific Northwest Laboratory conducted experiments at Aberdeen Proving Grounds, Maryland, to characterize the airborne depleted uranium (DU) resulting from the test firings of 105-mm, APFSDS-T XM774 ammunition. The goal was to obtain data pertinent to evaluations of human inhalation exposure to the airborne DU. Data was desired concerning the following: (1) size distribution of airborne DU; (2) quantity of airborne DU; (3) dispersion of airborne DU from the target vicinity; (4) amount of DU deposited on the ground; (5) solubility of airborne DU compounds in lung fluid; and (6) oxide forms of airborne and fallout DU. The experiments involved extensive air sampling for total airborne DU particulates and respirable DU particles both above the targets and at distances downwind. Fallout and fragments were collected around the target area. High-speed movies of the smoke generated from the impact of the penetrators were taken to estimate the cloud volumes. Results of the experiments are presented

  6. Strengthening mechanisms and fracture surface characteristics of silicate glass matrix composites with inclusion of alumina particles of different particle sizes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Minghui, E-mail: mhchen@imr.ac.cn [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhu, Shenglong; Wang, Fuhui [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2013-03-15

    Strengthening mechanisms of silicate glass by the inclusion of alumina particles of different volume fractions and different particle sizes are reported. The formulas of three responsible strengthening mechanisms, based on inclusion/crack interactions and interfacial elemental diffusion, were deduced; these include crack deflection, crack bridging and interdiffusion. The strength of the glass/alumina composites increased with inclusion fraction, but followed strengthening mechanisms that varied with alumina particle size. Crack deflection and bridging mechanisms dominated in strengthening for the glass/alumina (at mean particle size of 6 μm) composites while interdiffusion mechanism played a major role in the glass/alumina (at mean particle size of 1 μm) composites. The theoretical deduction of strengthening mechanisms depending on the particle size of alumina inclusions was demonstrated by the experimental strength data and fracture surface characteristics of the glass/alumina composites.

  7. Strengthening mechanisms and fracture surface characteristics of silicate glass matrix composites with inclusion of alumina particles of different particle sizes

    International Nuclear Information System (INIS)

    Strengthening mechanisms of silicate glass by the inclusion of alumina particles of different volume fractions and different particle sizes are reported. The formulas of three responsible strengthening mechanisms, based on inclusion/crack interactions and interfacial elemental diffusion, were deduced; these include crack deflection, crack bridging and interdiffusion. The strength of the glass/alumina composites increased with inclusion fraction, but followed strengthening mechanisms that varied with alumina particle size. Crack deflection and bridging mechanisms dominated in strengthening for the glass/alumina (at mean particle size of 6 μm) composites while interdiffusion mechanism played a major role in the glass/alumina (at mean particle size of 1 μm) composites. The theoretical deduction of strengthening mechanisms depending on the particle size of alumina inclusions was demonstrated by the experimental strength data and fracture surface characteristics of the glass/alumina composites

  8. The permeability of poly-disperse porous media and effective particle size

    Science.gov (United States)

    Markicevic, B. I.; Preston, C.; Osterroth, S.; Iliev, O.; Hurwitz, M.

    2015-11-01

    The interactions between the fluid and solid phases in porous media account for the openness and length of the flow path that the fluid needs to travel within. The same reasoning applies for both mono- and poly-disperse media, and is reflected in the adoption of the same permeability models. The only difference is that an effective particle size diameter has to be used for the poly-disperse samples. A filtration experiment is used to form a particle layer, filter cake, consisting of particles of different sizes. Both inflow and outflow particle size distribution are measured by particle counting method, and from their difference, the particle size distribution in the cake is determined. In a set of experiments, the filtration history is altered by changing (i) filtration medium; (ii) suspension flow rate; and (iii) particle concentration, where in all cases investigated the cake permeability remains constant. In order to predict the permeability of poly-disperse cake from the analytical models, the particle size distribution moments are calculated, and the permeability is found for each moment. Comparing the experimental to the analytical permeability values the effective particle size is found, where the permeability calculated by using the harmonic mean of the particle size distribution reproduces the permeability experimental value best. Finally, in the parametric study, reducing the cake porosity and/or lowering the particle retention shifts effective particle size used in the permeability model toward higher moments of the particle size distribution function.

  9. Middle East Health and Air Quality Utilizing NASA EOS in the Saharan and Arabian Deserts to Examine Dust Particle Size and Mineralogy of Aerosols

    Science.gov (United States)

    Keeton, Tiffany; Barrick, Bradley; Cooksey, Kirstin; Cowart, Kevin; Florence, Victoria; Herdy, Claire; Padgett-Vasquez, Steve; Luvall, Jeffrey; Molthan, Andrew

    2012-01-01

    Ground-based studies conducted in Iraq have revealed the presence of potential human pathogens in airborne dust. According to the Environmental Protection Agency (EPA), airborne particulate matter below 2.5micron (PM2.5) can cause long-term damage to the human respiratory system. NASA fs Earth Observing System (EOS) can be used to determine spectral characteristics of dust particles and dust particle sizes. Comparing dust particle size from the Sahara and Arabian Deserts gives insight into the composition and atmospheric transport characteristics of dust from each desert. With the use of NASA SeaWiFS DeepBlue Aerosol, dust particle sizes were estimated using Angstrom Exponent. Brightness Temperature Difference (BTD) equation was used to determine the area of the dust storm. The Moderate-resolution Imaging Spectroradiometer (MODIS) on Terra satellite was utilized in calculating BTD. Mineral composition of a dust storm that occurred 17 April 2008 near Baghdad was determined using imaging spectrometer data from the JPL Spectral Library and EO-1 Hyperion data. Mineralogy of this dust storm was subsequently compared to that of a dust storm that occurred over the Bodele Depression in the Sahara Desert on 7 June 2003.

  10. ESTIMATING SOIL PARTICLE-SIZE DISTRIBUTION FOR SICILIAN SOILS

    Directory of Open Access Journals (Sweden)

    Vincenzo Bagarello

    2009-09-01

    Full Text Available The soil particle-size distribution (PSD is commonly used for soil classification and for estimating soil behavior. An accurate mathematical representation of the PSD is required to estimate soil hydraulic properties and to compare texture measurements from different classification systems. The objective of this study was to evaluate the ability of the Haverkamp and Parlange (HP and Fredlund et al. (F PSD models to fit 243 measured PSDs from a wide range of 38 005_Bagarello(547_33 18-11-2009 11:55 Pagina 38 soil textures in Sicily and to test the effect of the number of measured particle diameters on the fitting of the theoretical PSD. For each soil textural class, the best fitting performance, established using three statistical indices (MXE, ME, RMSE, was obtained for the F model with three fitting parameters. In particular, this model performed better in the fine-textured soils than the coarse-textured ones but a good performance (i.e., RMSE < 0.03 was detected for the majority of the investigated soil textural classes, i.e. clay, silty-clay, silty-clay-loam, silt-loam, clay-loam, loamy-sand, and loam classes. Decreasing the number of measured data pairs from 14 to eight determined a worse fitting of the theoretical distribution to the measured one. It was concluded that the F model with three fitting parameters has a wide applicability for Sicilian soils and that the comparison of different PSD investigations can be affected by the number of measured data pairs.

  11. Carbon-based phytoplankton size classes retrieved via ocean color estimates of the particle size distribution

    Directory of Open Access Journals (Sweden)

    T. S. Kostadinov

    2015-05-01

    Full Text Available Owing to their important roles in biogeochemical cycles, phytoplankton functional types (PFTs have been the aim of an increasing number of ocean color algorithms. Yet, none of the existing methods are based on phytoplankton carbon (C biomass, which is a fundamental biogeochemical and ecological variable and the "unit of accounting" in Earth System models. We present a novel bio-optical algorithm to retrieve size-partitioned phytoplankton carbon from ocean color satellite data. The algorithm is based on existing algorithms to estimate particle volume from a power-law particle size distribution (PSD. Volume is converted to carbon concentrations using a compilation of allometric relationships. We quantify absolute and fractional biomass in three PFTs based on size – picophytoplankton (0.5–2 μm in diameter, nanophytoplankton (2–20 μm and microphytoplankton (20–50 μm. The mean spatial distributions of total phytoplankton C biomass and individual PFTs, derived from global SeaWiFS monthly ocean color data, are consistent with current understanding of oceanic ecosystems, i.e. oligotrophic regions are characterized by low biomass and dominance of picoplankton, whereas eutrophic regions have large biomass to which nanoplankton and microplankton contribute relatively larger fractions. Global spatially integrated phytoplankton carbon biomass standing stock estimates using our PSD-based approach yield on average ~0.2–0.3 Gt of C, consistent with analogous estimates from two other ocean color algorithms, and several state-of-the-art Earth System models. However, the range of phytoplankton C biomass spatial variability globally is larger than estimated by any other models considered here, because the PSD-based algorithm is not a priori empirically constrained and introduces improvement over the assumptions of the other approaches. Satisfactory in situ closure observed between PSD and POC measurements lends support to the theoretical basis of the

  12. Event-based total suspended sediment particle size distribution model

    Science.gov (United States)

    Thompson, Jennifer; Sattar, Ahmed M. A.; Gharabaghi, Bahram; Warner, Richard C.

    2016-05-01

    One of the most challenging modelling tasks in hydrology is prediction of the total suspended sediment particle size distribution (TSS-PSD) in stormwater runoff generated from exposed soil surfaces at active construction sites and surface mining operations. The main objective of this study is to employ gene expression programming (GEP) and artificial neural networks (ANN) to develop a new model with the ability to more accurately predict the TSS-PSD by taking advantage of both event-specific and site-specific factors in the model. To compile the data for this study, laboratory scale experiments using rainfall simulators were conducted on fourteen different soils to obtain TSS-PSD. This data is supplemented with field data from three construction sites in Ontario over a period of two years to capture the effect of transport and deposition within the site. The combined data sets provide a wide range of key overlooked site-specific and storm event-specific factors. Both parent soil and TSS-PSD in runoff are quantified by fitting each to a lognormal distribution. Compared to existing regression models, the developed model more accurately predicted the TSS-PSD using a more comprehensive list of key model input parameters. Employment of the new model will increase the efficiency of deployment of required best management practices, designed based on TSS-PSD, to minimize potential adverse effects of construction site runoff on aquatic life in the receiving watercourses.

  13. Influence of instruments performance and material properties on exposure assessment of airborne engineered nanomaterials

    DEFF Research Database (Denmark)

    Levin, Marcus

    particle number concentration. Measured size distributions with particle modes above 150 nm should not be deemed reliable as they might arise from misclassification of larger size particles. 4) That current methods for real-time measurement of lung-deposited surface area concentration for airborne...

  14. Toxicogenomic analysis of the particle dose- and size-response relationship of silica particles-induced toxicity in mice

    Science.gov (United States)

    Lu, Xiaoyan; Jin, Tingting; Jin, Yachao; Wu, Leihong; Hu, Bin; Tian, Yu; Fan, Xiaohui

    2013-01-01

    This study investigated the relationship between particle size and toxicity of silica particles (SP) with diameters of 30, 70, and 300 nm, which is essential to the safe design and application of SP. Data obtained from histopathological examinations suggested that SP of these sizes can all induce acute inflammation in the liver. In vivo imaging showed that intravenously administrated SP are mainly present in the liver, spleen and intestinal tract. Interestingly, in gene expression analysis, the cellular response pathways activated in the liver are predominantly conserved independently of particle dose when the same size SP are administered or are conserved independently of particle size, surface area and particle number when nano- or submicro-sized SP are administered at their toxic doses. Meanwhile, integrated analysis of transcriptomics, previous metabonomics and conventional toxicological results support the view that SP can result in inflammatory and oxidative stress, generate mitochondrial dysfunction, and eventually cause hepatocyte necrosis by neutrophil-mediated liver injury.

  15. Toxicogenomic analysis of the particle dose- and size-response relationship of silica particles-induced toxicity in mice

    International Nuclear Information System (INIS)

    This study investigated the relationship between particle size and toxicity of silica particles (SP) with diameters of 30, 70, and 300 nm, which is essential to the safe design and application of SP. Data obtained from histopathological examinations suggested that SP of these sizes can all induce acute inflammation in the liver. In vivo imaging showed that intravenously administrated SP are mainly present in the liver, spleen and intestinal tract. Interestingly, in gene expression analysis, the cellular response pathways activated in the liver are predominantly conserved independently of particle dose when the same size SP are administered or are conserved independently of particle size, surface area and particle number when nano- or submicro-sized SP are administered at their toxic doses. Meanwhile, integrated analysis of transcriptomics, previous metabonomics and conventional toxicological results support the view that SP can result in inflammatory and oxidative stress, generate mitochondrial dysfunction, and eventually cause hepatocyte necrosis by neutrophil-mediated liver injury. (paper)

  16. CONTROL OF POLYMER PARTICLE SIZE USING POROUS GLASS MEMBRANE EMULSIFICATION A REVIEW

    Institute of Scientific and Technical Information of China (English)

    Guanghui Ma

    2003-01-01

    Much attention has in recent years been paid to fine applications of polymer particles, e.g., carrier for enzyme, separation media for protein, DNA and cell, and carrier for drug in Drug Delivery System (DDS). Control of polymer particle size is especially important in such fine applications. For instance, when the particles are used as a carrier of anti-cancer agents, the locations of particles containing anti-cancer agents also depend on the size of the particles. In this paper, various techniques of controlling polymer particle size are described, with emphasis on Shirasu Porous Glass (SPG) membrane emulsification, as carried out in our research group.

  17. Comparison fo CO2 Lidar Backscatter with Particle Size Distribution and GOES-7 Data in Hurricane Juliette

    Science.gov (United States)

    Jarzembski, Maurice A.; Srivastava, Vandana; McCaul, Eugene W., Jr.; Jedlovec, Gary J.; Atkinson, Robert J.; Pueschel, Rudy F.; Cutten, Dean R.

    1999-01-01

    Two NASA/MSFC continuous wave (CW) focused Doppler lidars obtained in-situ high resolution calibrated backscatter measurements in the upper levels of Hurricane Juliette as part of the 1995 NASA/Multicenter Airborne Coherent Atmospheric Wind Sensor (MACAWS) mission on board NASA's DC8 aircraft. These were also intercompared with in-situ cloud particle size distributions obtained from NASA/Ames Research Center's forward scattering spectrometer probe (FSSP), the DC8 aircraft infrared (IR) surface temperature radiometer data, and the Geostationary Operational Environmental Satellites (GOES-7) 11 micrometer IR emission images with their corresponding estimates of cloud top temperature and height. Two traverses of Hurricane Juliette's eye were made off the west coast of Mexico at altitude approx. 11.7 km on 21 September 1995. During this DC8 flight, late stages of eyewall decay-replacement cycles were observed, giving the appearance of an annular eye with clouds in the central region.

  18. 激光尘埃粒子计数器反射腔偏差分析%Error Analysis of Reflecting mirror of Airborne Particle Counter

    Institute of Scientific and Technical Information of China (English)

    王卫芳

    2011-01-01

    目前激光尘埃粒子计数器的应用非常广泛,但各方面参数的选择还都不是很完善。将激光尘埃粒子计器的反射腔工作原理建立了几何模型,用数学公式表达出气溶胶粒子偏离焦点后在反射腔上的偏差,为实际生产和使用提供了依据。%Recently,The Airborne Particle Counter is used widely,however,its choose of parameters is not very perfect.In this particle,a geometric model of mirror in Airborne Particle Counter was established,expressed in mathematical formula for error in reflect cavity besause of Particles off the focus,This will offer some references to practices.

  19. Particle sizing calibration with refractive index correction for light scattering optical particle counters and impacts upon PCASP and CDP data collected during the Fennec campaign

    Directory of Open Access Journals (Sweden)

    P. D. Rosenberg

    2012-05-01

    Full Text Available Optical particle counters (OPCs are used regularly for atmospheric research, measuring particle scattering cross sections to generate particle size distribution histograms. This manuscript presents two methods for calibrating OPCs with case studies based on a Passive Cavity Aerosol Spectrometer Probe (PCASP and a Cloud Droplet Probe (CDP, both of which are operated on the Facility for Airborne Atmospheric Measurements BAe-146 research aircraft.

    A probability density function based method is provided for modification of the OPC bin boundaries when the scattering properties of measured particles are different to those of the calibration particles due to differences in refractive index or shape. This method provides mean diameters and widths for OPC bins based upon Mie-Lorenz theory or any other particle scattering theory, without the need for smoothing, despite the highly nonlinear and non-monotonic relationship between particle size and scattering cross section. By calibrating an OPC in terms of its scattering cross section the optical properties correction can be applied with minimal information loss, and performing correction in this manner provides traceable and transparent uncertainty propagation throughout the whole process.

    Analysis of multiple calibrations has shown that for the PCASP the bin centres differ by up to 30% from the manufacturer's nominal values and can change by up to approximately 20% when routine maintenance is performed. The CDP has been found to be less sensitive than the manufacturer's specification with differences in sizing of between 1.6 ± 0.8 μm and 4.7 ± 1.8 μm for one flight. Over the course of the Fennec project in the Sahara the variability of calibration was less than the calibration uncertainty in 6 out of 7 calibrations performed.

    As would be expected from Mie-Lorenz theory, the impact of the refractive index corrections has been found to be largest for absorbing materials and

  20. Particle sizing calibration with refractive index correction for light scattering optical particle counters and impacts upon PCASP and CDP data collected during the Fennec campaign

    Science.gov (United States)

    Rosenberg, P. D.; Dean, A. R.; Williams, P. I.; Dorsey, J. R.; Minikin, A.; Pickering, M. A.; Petzold, A.

    2012-05-01

    Optical particle counters (OPCs) are used regularly for atmospheric research, measuring particle scattering cross sections to generate particle size distribution histograms. This manuscript presents two methods for calibrating OPCs with case studies based on a Passive Cavity Aerosol Spectrometer Probe (PCASP) and a Cloud Droplet Probe (CDP), both of which are operated on the Facility for Airborne Atmospheric Measurements BAe-146 research aircraft. A probability density function based method is provided for modification of the OPC bin boundaries when the scattering properties of measured particles are different to those of the calibration particles due to differences in refractive index or shape. This method provides mean diameters and widths for OPC bins based upon Mie-Lorenz theory or any other particle scattering theory, without the need for smoothing, despite the highly nonlinear and non-monotonic relationship between particle size and scattering cross section. By calibrating an OPC in terms of its scattering cross section the optical properties correction can be applied with minimal information loss, and performing correction in this manner provides traceable and transparent uncertainty propagation throughout the whole process. Analysis of multiple calibrations has shown that for the PCASP the bin centres differ by up to 30% from the manufacturer's nominal values and can change by up to approximately 20% when routine maintenance is performed. The CDP has been found to be less sensitive than the manufacturer's specification with differences in sizing of between 1.6 ± 0.8 μm and 4.7 ± 1.8 μm for one flight. Over the course of the Fennec project in the Sahara the variability of calibration was less than the calibration uncertainty in 6 out of 7 calibrations performed. As would be expected from Mie-Lorenz theory, the impact of the refractive index corrections has been found to be largest for absorbing materials and the impact on Saharan dust measurements made

  1. Effects of concentration of dispersions on particle sizing during production of fine particles in wet grinding process

    OpenAIRE

    Inam, Muhammad Asif; Ouattara, Soualo; Frances, Christine

    2011-01-01

    Stirred media milling is a prospective technology for producing colloidal dispersions by means of wet grinding process. In the past, many researchers have studied the effects of different operating parameters such as size, shape, nature and quantity of grinding medium, the speed of agitator in grinding chamber, the feed rate of dispersions, etc. in stirred media mills. However, it is still less known how particle sizing which generates valuable information of particle size of the product to i...

  2. PARTICLE SIZE ESTIMATION AND ELEMENTAL ANALYSIS OF LAUHA BHASMA

    Directory of Open Access Journals (Sweden)

    Singh Neetu

    2011-02-01

    Full Text Available Ayurveda is the science of life. It consists of medicaments prepared by materials obtained from nature, viz; plant products, animal products and metal/ mineral products. Converting the metals/minerals into acceptable form (i.e bhasma preparation for internal administration is done by following various pharmaceutical processing methods. These methods are extensively mentioned in Rasa Shastra (A branch of Ayurveda. Lauha (iron is one of the most important metals mentioned in Rasa Shastra for preparing Lauha bhasma. As iron supplementation is required for formation of hemoglobin of blood and is most essential component for maintaining physiological condition of the body system, in Ayurveda utmost importance is given for Lauha bhasma preparation and also Lauha bhasma were used for preparing many number of Ayurvedic dosage form. In ancient pharmaceutical science of Ayurveda to determine the quality of bhasma certain testing procedures have been mentioned such as varitar, rekhapurnata etc. but in present day scenario apart from these testing procedure there is a need of more sophisticated testing methods for determining quality of Lauha bhasma. In present study Lauha bhsma has been prepared by following Ayurvedic textual reference. After preparation of Lauha bhasma it is subjected to various testing procedures like AAS, EDAX, SEM and TEM. The details including results of these testing procedures with illustrated photographs, tables etc. are mentioned in the paper. SEM & TEM result confirms the formation of nanoparticles after 20th puta. Decrease in particle size after successive steps is observed. Whereas tests like AAS and EDAX show incorporation of trace elements in the finally prepared bhasma.

  3. Airborne dust and soil particles at the Phoenix landing site, Mars

    DEFF Research Database (Denmark)

    Madsen, M. B.; Drube, L.; Goetz, W.;

    . Because of the multiple background colors of the iSweeps the effect of the translucence of thin dust layers can be studied. This is used to estimate the rate of dust accumulation and will be used to evaluate light scattering properties of the particles. Some particles raised by the retro-rockets during...

  4. Mobility particle size spectrometers: harmonization of technical standards and data structure to facilitate high quality long-term observations of atmospheric particle number size distributions

    Directory of Open Access Journals (Sweden)

    A. Wiedensohler

    2012-03-01

    Full Text Available Mobility particle size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers or SMPS (Scanning Mobility Particle Sizers have found a wide range of applications in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards and guidelines with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. Technical standards were developed for a minimum requirement of mobility size spectrometry to perform long-term atmospheric aerosol measurements. Technical recommendations include continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyzer.

    We compared commercial and custom-made inversion routines to calculate the particle number size distributions from the measured electrical mobility distribution. All inversion routines are comparable within few per cent uncertainty for a given set of raw data.

    Furthermore, this work summarizes the results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research and ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network to determine present uncertainties especially of custom-built mobility particle size spectrometers. Under controlled laboratory conditions, the particle number size distributions from 20 to 200 nm determined by mobility particle size spectrometers of different design are within an uncertainty range of around ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. For particles larger than 200 nm, the uncertainty range increased to 30%, which could not be explained. The network reference mobility spectrometers with identical design agreed within ±4% in the

  5. Concentration and Particle Size of Airborne Toxic Algae (Brevetoxin) Derived from Ocean Red Tide Events

    OpenAIRE

    Cheng, Yung Sung; McDonald, Jacob D.; Kracko, Dean; Irvin, C. Mitch; Zhou, Yue; Pierce, Richard H.; Henry, Michael S.; Bourdelaisa, Andrea; Naar, Jerome; Baden, Daniel G.

    2005-01-01

    Red tides in the Gulf of Mexico are formed by blooms of the dinoflagellate Karenia brevis, which produces brevetoxins (PbTx). Brevetoxins can be transferred from water to air in the wind-powered whitecapped waves during red tide episodes. Inhalation exposure to marine aerosol containing PbTx causes respiratory problems. A liquid chromatograph/ tandem mass spectrometric method was developed for the detection and quantitation of several PbTxs in ambient samples collected during red tide events....

  6. Nano-sized ceria particles prepared by spray pyrolysis using polymeric precursor solution

    International Nuclear Information System (INIS)

    Nano-sized ceria particles were prepared from the aqueous solution containing the polymeric precursors by ultrasonic spray pyrolysis at the severe preparation conditions such as high flow rate of carrier gas and short residence time. The key idea to produce nanoparticles was to prepare hollow ceria particles which are easily turned to aggregates of nano-sized primary particles during the post-thermal treatment and thereafter disintegrate such aggregates to nano-sized particles by a simple ball milling process. It was found that using the polymeric precursor strongly influences the crystallization characteristics and morphological changes of the as-prepared particles during the post-thermal treatment. The as-prepared particles prepared from the polymeric precursor solution had non-spherical shape and fractured structure with a thin shell, whereas the as-prepared and calcined ceria particles obtained from the aqueous solution had spherical shape and hollow morphology with a thick shell. Also, nano-sized ceria particles prepared from the polymeric precursor solution had less aggregated structure than those prepared from the aqueous solution. For the ceria particles prepared from the polymeric precursor solution, the degree of aggregation between the primary particles was reduced as increasing the calcination temperature. As a result, aggregation-free nano-sized ceria particles were obtained above 1200 deg. C without a milling process. The mean size of the primary particles increased from several tens nanometer to submicrometer size as the calcination temperature changed from 800 to 1300 deg. C

  7. Understanding particle size and distance driven competition of interparticle interactions and effective single-particle anisotropy

    Science.gov (United States)

    Pacakova, B.; Mantlikova, A.; Niznansky, D.; Kubickova, S.; Vejpravova, J.

    2016-05-01

    Magnetic response of single-domain nanoparticles (NPs) in concentrated systems is strongly affected by mutual interparticle interactions. However, particle proximity significantly influences single-particle effective anisotropy. To solve which of these two phenomena plays a dominant role in the magnetic response of real NP systems, systematic study on samples with well-defined parameters is required. In our work, we prepared a series of nanocomposites constituted of highly-crystalline and well-isolated CoFe2O4 NPs embedded in an amorphous SiO2 matrix using a single-molecule precursor method. This preparation method enabled us to reach a wide interval of particle size and concentration. We observed that the characteristic parameters of the single-domain state (coercivity, blocking temperature) and dipole–dipole interaction energy ({{E}\\text{d-\\text{d}}} ) scaled with each other and increased with increasing {{≤ft({{d}\\text{XRD}}/r\\right)}3} , where d XRD was the NP diameter and r was the interparticle distance. Our results are in excellent agreement with Monte-Carlo simulations of the particle growth. Moreover, we demonstrated that the contribution of {{E}\\text{d-\\text{d}}} acting as an additional energetic barrier to the superspin reversal or as an average static field did not sufficiently explain how the concentrated NP systems responded to an external magnetic field. Alternations in the blocking temperature and coercivity of our NP systems accounted for reformed relaxations of the NP superspins and modified effective anisotropy energy of the interacting NPs. Therefore, the concept of modified NP effective anisotropy explains the magnetic response of our concentrated NP systems better than the concept of the energy barrier influenced by interparticle interactions.

  8. Understanding particle size and distance driven competition of interparticle interactions and effective single-particle anisotropy.

    Science.gov (United States)

    Pacakova, B; Mantlikova, A; Niznansky, D; Kubickova, S; Vejpravova, J

    2016-05-25

    Magnetic response of single-domain nanoparticles (NPs) in concentrated systems is strongly affected by mutual interparticle interactions. However, particle proximity significantly influences single-particle effective anisotropy. To solve which of these two phenomena plays a dominant role in the magnetic response of real NP systems, systematic study on samples with well-defined parameters is required. In our work, we prepared a series of nanocomposites constituted of highly-crystalline and well-isolated CoFe2O4 NPs embedded in an amorphous SiO2 matrix using a single-molecule precursor method. This preparation method enabled us to reach a wide interval of particle size and concentration. We observed that the characteristic parameters of the single-domain state (coercivity, blocking temperature) and dipole-dipole interaction energy ([Formula: see text]) scaled with each other and increased with increasing [Formula: see text], where d XRD was the NP diameter and r was the interparticle distance. Our results are in excellent agreement with Monte-Carlo simulations of the particle growth. Moreover, we demonstrated that the contribution of [Formula: see text] acting as an additional energetic barrier to the superspin reversal or as an average static field did not sufficiently explain how the concentrated NP systems responded to an external magnetic field. Alternations in the blocking temperature and coercivity of our NP systems accounted for reformed relaxations of the NP superspins and modified effective anisotropy energy of the interacting NPs. Therefore, the concept of modified NP effective anisotropy explains the magnetic response of our concentrated NP systems better than the concept of the energy barrier influenced by interparticle interactions. PMID:27122013

  9. Dynamics of finite size neutrally buoyant particles in isotropic turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Elhimer, M; Jean, A; Praud, O; Bazile, R; Marchal, M; Couteau, G, E-mail: elhimer@imft.fr [Universite de Toulouse, INPT, UPS, IMFT - Institut de Mecanique des Fluides de Toulouse, Allee Camille Soula, F-31400 Toulouse (France); CNRS, IMFT, F-31400 Toulouse (France)

    2011-12-22

    The dynamics of neutrally buoyant particles suspended in a turbulent flow is investigated experimentally, with particles having diameters larger than the Kolmogorov length scale. To that purpose, a turbulence generator have been constructed and the resulting flow characterized. The fluid was then seeded with polystyrene particles of diameter about 1 mm and their velocity measured separately and simultaneously with the surrounding fluid. Comparison of the velocities statistics between the two phases shows no appreciable discrepancy. However, simultaneous velocity measurement shows that particles may move in different direction from the underlying flow.

  10. Taille des particules et catalyse Particle Size and Catalysis

    Directory of Open Access Journals (Sweden)

    Boitiaux J. P.

    2006-11-01

    hydrogène pouvaient tout à fait rendre compte des phénomènes observés. En plus de cela un métal déposé sur silice et un métal déposé sur alumine peuvent se comporter de façon tout à fait différente. Tout ceci montre que certaines interprétations sont trop simplistes et que faire varier la taille des particules par n'importe quel moyen et étudier les conséquences sur l'acte catalytique n'est pas suffisant. Les deux approches complémentaires, celle du cristallographe qui tente de décrire les petites particules à partir des paramètres du métal massique et celle du chimiste qui tente de déduire la structure du comportement du catalyseur observé dans la réaction étudiée, n'arrivent pas vraiment à se rejoindre pour aboutir à une description en tout point acceptable de la structure de la particule. D'un côté le physico-chimiste utilise des simplifications outrancières lorsqu'il tente de décrire ses structures grâce à l'usage de fonctions d'état qui n'ont pas toujours des solutions évidentes. D'un autre le chimiste manipule des objets réels mais arrive difficilement à isoler le paramètre qu'il veut étudier. Ses conclusions ne sont jamais à l'abri des artefacts apportés par les conditions opératoires ou les effets de support. Ce dilemme existe aussi pour le physicien qui tente de synthétiser des agrégats bien définis dans un flux gazeux mais loin de la réalité de la catalyse. De même pour le chimiste qui veut ramener les effets de structure à de simples comparaisons entre les faces exposées par les monocristaux. Néanmoins l'apport des deux est indispensable car ils donnent des idées directrices indispensables pour l'homme de catalyse qui tente de maîtriser l'ensemble des paramètres. While heterogeneous catalysis, and especially catalysis by metals, is concerned with the size of the particles and hence with the developed surface area, this is not only to prepare an effective product at minimum cost. The study of the

  11. Research on bimodal particle extinction coefficient during Brownian coagulation and condensation for the entire particle size regime

    International Nuclear Information System (INIS)

    The extinction coefficient of atmospheric aerosol particles influences the earth’s radiation balance directly or indirectly, and it can be determined by the scattering and absorption characteristics of aerosol particles. The problem of estimating the change of extinction coefficient due to time evolution of bimodal particle size distribution is studied, and two improved methods for calculating the Brownian coagulation coefficient and the condensation growth rate are proposed, respectively. Through the improved method based on Otto kernel, the Brownian coagulation coefficient can be expressed simply in powers of particle volume for the entire particle size regime based on the fitted polynomials of the mean enhancement function. Meanwhile, the improved method based on Fuchs–Sutugin kernel is developed to obtain the condensation growth rate for the entire particle size regime. And then, the change of the overall extinction coefficient of bimodal distributions undergoing Brownian coagulation and condensation can be estimated comprehensively for the entire particle size regime. Simulation experiments indicate that the extinction coefficients obtained with the improved methods coincide fairly well with the true values, which provide a simple, reliable, and general method to estimate the change of extinction coefficient for the entire particle size regime during the bimodal particle dynamic processes.

  12. Element content and particle size characterization of a mussel candidate reference material

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Edson G.; Vasconcellos, Marina B.A., E-mail: emoreira@ipen.b, E-mail: mbvascon@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro do Reator de Pesquisas; Santos, Rafaela G. dos; Martinelli, Jose R., E-mail: jroberto@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencias e Tecnologia de Materiais

    2011-07-01

    The use of certified reference materials is an important tool in the quality assurance of analytical measurements. To assure reliability on recently prepared powder reference materials, not only the characterization of the property values of interest and their corresponding uncertainties, but also physical properties such as the particle size distribution must be well evaluated. Narrow particle size distributions are preferable than larger ones; as different size particles may have different analyte content. Due to this fact, the segregation of the coarse and the fine particles in a bottle may lead to inhomogeneity of the reference material, which should be avoided. In this study the element content as well as the particle size distribution of a mussel candidate reference material produced at IPEN-CNEN/SP was investigated. Instrumental Neutron Activation Analysis was applied to the determination of 15 elements in seven fractions of the material with different particle size distributions. Subsamples of the materials were irradiated simultaneously with elemental standards at the IEA-R1 research nuclear reactor and the induced gamma ray energies were measured in a hyperpure germanium detector. Three vials of the candidate reference material and three coarser fractions, collected during the preparation, were analyzed by Laser Diffraction Particle Analysis to determine the particle size distribution. Differences on element content were detected for fractions with different particle size distribution, indicating the importance of particle size control for biological reference materials. From the particle size analysis, Gaussian particle size distribution was observed for the candidate reference material with mean particle size {mu} = 94.6 {+-} 0.8 {mu}m. (author)

  13. An experimental and theoretical study of the seepage migration of suspended particles with different sizes

    Science.gov (United States)

    Bai, Bing; Xu, Tao; Guo, Zhiguang

    2016-08-01

    This study experimentally investigates the effect of particle size, particle concentration and flow velocity on the migration of suspended particles of size 1.02-47 μm in porous media. The results show that at the same flow velocity, the peak values of the breakthrough curves decrease and corresponding pore volumes increase slightly with increasing particles size. The migration velocity of smaller suspended particles is even greater than water flow velocity, which is attributed to the size exclusion effect. With increase of the injected particle concentration, the deposition coefficients of small single particles increase at first and then tend to a steady state or even decrease slightly, explained by the maximum retention concentration. The dispersivity of small particles decreases with increasing velocity. However, at a high flow velocity, the hydrodynamic dispersivity becomes increasingly dominant with the increase of particle size. The deposition coefficients for large-sized particles are higher than those for small-sized particles, which is attributed to considerable mass removal due to straining. An analytical solution, considering the release effect of sorbed particles, is developed to account for the one-dimensional flow and dispersive effect using a source function method, and then three transport parameters—dispersivity, deposition coefficient and release coefficient—are fitted using the experimental results. Finally, suspended-particle migration is predicted by the proposed model for short-time constant-concentration injection and repeated three-pulse injection. Overall, particle size has a significant effect on the seepage migration parameters of suspended particles in porous media such as the particle velocity, dispersivity and deposition coefficient.

  14. Simultaneous measurement of Ni-Al particle size, velocity, and temperature in atmospheric thermal plasmas

    International Nuclear Information System (INIS)

    A technique for simultaneously measuring particle size, velocity, and temperature has been applied to the in-flight characterization of a Ni--Al particles sprayed in a 28 kW plasma torch. The radial distribution of particle size, velocity, temperature and particle concentration were obtained at stand off distances between 63.5 and 88.9 mm. These measurements and their relationship to the characteristics of the resulting coating are discussed. Injection geometry dependent particle sizing and an apparant fracturing of the original particles into smaller particles was observed. A significant fraction of the largest particles observed did not appear to the molten. Particle behavior was found to be relatively insensitive to gas mixture and flow rate. 1 ref., 8 figs

  15. Variation of particle number concentration and size distributions at the urban environment in Vilnius (Lithuania)

    Science.gov (United States)

    Ulevicius, Vidmantas; Byčenkienë, Steigvilë; Plauškaitë, Kristina; Dudoitis, Vadimas

    2013-05-01

    This study presents results of research on urban aerosol particles with a focus on the particle size distribution and the aerosol particle number concentration (PNC). The real time measurements of the aerosol PNC in the size range of 9-840 nm were performed at the urban background site using a Condensed Particle Counter and Scanning Mobility Particle Sizer (SMPS). Strong diurnal patterns in aerosol PNC were evident as a direct effect of three sources of the aerosol particles (nucleation, traffic, and residential heating appliances). The traffic exhaust emissions were a major contributor of the pollution observed at the roadside site that was dominated by the nucleation mode particles, while particles formed due to the residential heating appliances and secondary formation processes contributed to the accumulation mode particles and could impact the variation of PNC and its size distribution during the same day.

  16. Particle diffusion in active fluids is non-monotonic in size.

    Science.gov (United States)

    Patteson, Alison E; Gopinath, Arvind; Purohit, Prashant K; Arratia, Paulo E

    2016-02-28

    We experimentally investigate the effect of particle size on the motion of passive polystyrene spheres in suspensions of Escherichia coli. Using particles covering a range of sizes from 0.6 to 39 microns, we probe particle dynamics at both short and long time scales. In all cases, the particles exhibit super-diffusive ballistic behavior at short times before eventually transitioning to diffusive behavior. Surprisingly, we find a regime in which larger particles can diffuse faster than smaller particles: the particle long-time effective diffusivity exhibits a peak in particle size, which is a deviation from classical thermal diffusion. We also find that the active contribution to particle diffusion is controlled by a dimensionless parameter, the Péclet number. A minimal model qualitatively explains the existence of the effective diffusivity peak and its dependence on bacterial concentration. Our results have broad implications on characterizing active fluids using concepts drawn from classical thermodynamics. PMID:26797039

  17. Lattice Constant Dependence on Particle Size for Ceria prepared from a Citrate Sol-Gel

    Science.gov (United States)

    Morris, V. N.; Farrell, R. A.; Sexton, A. M.; Morris, M. A.

    2006-02-01

    High surface area ceria nanoparticles have been prepared using a citrate solgel precipitation method. Changes to the particle size have been made by calcining the ceria powders at different temperatures, and X-ray methods used to determine their lattice parameters. The particle sizes have been assessed using transmission electron microscopy (TEM) and the lattice parameter found to fall with decreasing particle size. The results are discussed in the light of the role played by surface tension effects.

  18. The effect of particle size on the rheological properties of polyamide 6/biochar composites

    Science.gov (United States)

    Huber, Tim; Misra, Manjusri; Mohanty, Amar K.

    2015-05-01

    To assess the potential of biochar as filler for thermoplastic materials and to optimize its processing conditions, composites of polyamide 6 and biochar were produced by extrusion followed by injection moulding. Biochar was prepared by grinding and ball-milling, respectively before addition to the polymer. The different biochar treatments resulted in strong differences in the mean particle size as well as the particle size distribution. The size of the filler particle significantly influences the flow behaviour of the melt.

  19. The effect of particle size and porosity on spectral contrast in the mid-infrared

    Science.gov (United States)

    Salisbury, J.W.; Eastes, J.W.

    1985-01-01

    Contrary to previous work, we find that the decreasing intensity of fundamental molecular vibration bands with decreasing particle size is due primarily to increasing porosity of the finer particle size ranges, rather than to particle size per se. This implies that laser reflectance measurements from orbiting spacecraft should avoid loss of spectral contrast for fine particulate surfaces, because such measurements near zero phase angle will benefit from the opposition effect. ?? 1985.

  20. Performance of diethylene glycol-based particle counters in the sub-3 nm size range

    CERN Document Server

    Wimmer, D; Franchin, A; Kangasluoma, J; Kreissl, F; Kürten, A; Kupc, A; Metzger, A; Mikkilä, J; Petäjä, J; Riccobono, F; Vanhanen, J; Kulmala, M; Curtius, J

    2013-01-01

    When studying new particle formation, the uncertainty in determining the "true" nucleation rate is considerably reduced when using condensation particle counters (CPCs) capable of measuring concentrations of aerosol particles at sizes close to or even at the critical cluster size (1–2 nm). Recently, CPCs able to reliably detect particles below 2 nm in size and even close to 1 nm became available. Using these instruments, the corrections needed for calculating nucleation rates are substantially reduced compared to scaling the observed formation rate to the nucleation rate at the critical cluster size. However, this improved instrumentation requires a careful characterization of their cut-off size and the shape of the detection efficiency curve because relatively small shifts in the cut-off size can translate into larger relative errors when measuring particles close to the cut-off size. Here we describe the development of two continuous-flow CPCs using diethylene glycol (DEG) as the working fluid. The desig...

  1. The future of airborne sulfur-containing particles in the absence of fossil fuel sulfur dioxide emissions.

    Science.gov (United States)

    Perraud, Véronique; Horne, Jeremy R; Martinez, Andrew S; Kalinowski, Jaroslaw; Meinardi, Simone; Dawson, Matthew L; Wingen, Lisa M; Dabdub, Donald; Blake, Donald R; Gerber, R Benny; Finlayson-Pitts, Barbara J

    2015-11-01

    Sulfuric acid (H2SO4), formed from oxidation of sulfur dioxide (SO2) emitted during fossil fuel combustion, is a major precursor of new airborne particles, which have well-documented detrimental effects on health, air quality, and climate. Another precursor is methanesulfonic acid (MSA), produced simultaneously with SO2 during the atmospheric oxidation of organosulfur compounds (OSCs), such as dimethyl sulfide. In the present work, a multidisciplinary approach is used to examine how contributions of H2SO4 and MSA to particle formation will change in a large coastal urban area as anthropogenic fossil fuel emissions of SO2 decline. The 3-dimensional University of California Irvine-California Institute of Technology airshed model is used to compare atmospheric concentrations of gas phase MSA, H2SO4, and SO2 under current emissions of fossil fuel-associated SO2 and a best-case futuristic scenario with zero fossil fuel sulfur emissions. Model additions include results from (i) quantum chemical calculations that clarify the previously uncertain gas phase mechanism of formation of MSA and (ii) a combination of published and experimental estimates of OSC emissions, such as those from marine, agricultural, and urban processes, which include pet waste and human breath. Results show that in the zero anthropogenic SO2 emissions case, particle formation potential from H2SO4 will drop by about two orders of magnitude compared with the current situation. However, particles will continue to be generated from the oxidation of natural and anthropogenic sources of OSCs, with contributions from MSA and H2SO4 of a similar order of magnitude. This could be particularly important in agricultural areas where there are significant sources of OSCs. PMID:26483454

  2. Phthalates in PM2.5 airborne particles in the Moravian-Silesian Region, Czech Republic

    OpenAIRE

    Jana Růžičková; Helena Raclavská; Konstantin Raclavský; Dagmar Juchelková

    2016-01-01

    Industrial area of the Moravian-Silesian Region (the Czech Republic) is highly polluted by air contaminants, especially emissions of particulate matter. Samples of PM2.5 particles were analysed by pyrolysis gas chromatography with mass spectrometric detection. Concentrations of phthalates were determined for the winter season, transitional period and the summer season. The relative concentrations of phthalates in PM2.5 particles have the same proportion in both heating and non-heating season:...

  3. Theoretical studies on bioaerosol particle size and shape measurement from spatial scattering profiles

    Institute of Scientific and Technical Information of China (English)

    Chunxia Feng; Lihua Huang; Jianbo Wang; Yongkai Zhao; Huijie Huang

    2011-01-01

    @@ A method of clarifying bioaerosol particles is proposed based on T-matrix.Size and shape characterizations are simultaneously acquired for individual bioaerosol particles by analyzing the spatial distribution of scattered light.The particle size can be determined according to the scattering intensity,while shape information can be obtained through asymmetry factor(AF).The azimuthal distribution of the scattered light for spherical particles is symmetrical,whereas it is asymmetrical for non-spherical ones,and the asymmetry becomes intense with increasing asphericity.The calculated results denote that the 50-100 scattering angle is an effective range to classify the bioaerosol particles that we axe concerned of.The method is very useful in real-time environmental monitoring of particle sizes and shapes.%A method of clarifying bioaerosol particles is proposed based on T-matrix. Size and shape characterizations are simultaneously acquired for individual bioaerosol particles by analyzing the spatial distribution of scattered light. The particle size can be determined according to the scattering intensity, while shape information can be obtained through asymmetry factor (AF). The azimuthal distribution of the scattered light for spherical particles is symmetrical, whereas it is asymmetrical for non-spherical ones, and the asymmetry becomes intense with increasing asphericity. The calculated results denote that the 5°-10° scattering angle is an effective range to classify the bioaerosol particles that we are concerned of. The method is very useful in real-time environmental monitoring of particle sizes and shapes.

  4. Cellulosic biomass pretreatment and sugar yields as a function of biomass particle size.

    Directory of Open Access Journals (Sweden)

    Michael J Dougherty

    Full Text Available Three lignocellulosic pretreatment techniques (ammonia fiber expansion, dilute acid and ionic liquid are compared with respect to saccharification efficiency, particle size and biomass composition. In particular, the effects of switchgrass particle size (32-200 on each pretreatment regime are examined. Physical properties of untreated and pretreated samples are characterized using crystallinity, surface accessibility measurements and scanning electron microscopy (SEM imaging. At every particle size tested, ionic liquid (IL pretreatment results in greater cell wall disruption, reduced crystallinity, increased accessible surface area, and higher saccharification efficiencies compared with dilute acid and AFEX pretreatments. The advantages of using IL pretreatment are greatest at larger particle sizes (>75 µm.

  5. Simulating the particle size distribution of rockfill materials based on its statistical regularity

    Institute of Scientific and Technical Information of China (English)

    YAN Zongling; QIU Xiande; YU Yongqiang

    2003-01-01

    The particle size distribution of rockfill is studied by using granular mechanics, mesomechanics and probability statistics to reveal the relationship of the distribution of particle size to that of the potential energy intensity before fragmentation,which finds out that the potential energy density has a linear relation to the logarithm of particle size and deduces that the distribution of the logarithm of particle size conforms to normal distribution because the distribution of the potential energy density does so. Based on this finding and by including the energy principle of rock fragmentation, the logarithm distribution model of particle size is formulated, which uncovers the natural characteristics of particle sizes on statistical distribution. Exploring the properties of the average value, the expectation, and the unbiased variance of particle size indicates that the expectation does notequal to the average value, but increases with increasing particle size and its ununiformity, and is always larger than the average value, and the unbiased variance increases as the ununiformity and geometric average value increase. A case study proves that the simulated results by the proposed logarithm distribution model accord with the actual data. It is concluded that the logarithm distribution model and Kuz-Ram model can be used to forecast the particle-size distribution of inartificial rockfill while for blasted rockfill, Kuz-Ram model is an option, and in combined application of the two models, it is necessary to do field tests to adjust some parameters of the model.

  6. Transport and Aggregation of Nanoparticles in Packed Beds: Effects of Pore Velocity and Initially-Fed Particle Size on Transient Particle Size Distributions

    Science.gov (United States)

    Pham, Ngoc; Papavassiliou, Dimitrios

    2015-11-01

    Aggregation of colloidal particles in flow through porous media has received careful consideration, as it reduces particle breakthrough due to pore clogging and sedimentation. Additionally, in unstable colloidal systems, deposition of colloidal aggregates on the pore surfaces can create sub-surfaces for further colloidal attachment. This phenomenon is known as ripening effect. In this study, transient particle size distributions of nano-particle systems, propagating in a bed packed with spheres are numerically investigated. In our simulation, only pair interactions are considered, and the aggregation rate is varied with the relative position of two particles in a pair. The packed bed consists of spheres of known size, randomly packed in a simulation box. To generate the velocity field of water inside the porous medium, the lattice Boltzmann method (LBM) is used. In conjunction with that, the trajectories of thousands of massless particles moving with the flow under convection and diffusion are recorded employing a Lagrangian framework. While pore clogging is neglected, we draw attention to the change of the distribution of particle size under different pore velocities and different initially-fed particle sizes.

  7. Singular Diffusion as a Function of Nanoparticles Size in Antimony Film-Selenium Particles and Antimony Film-Tellurium Particles

    International Nuclear Information System (INIS)

    A recently developed chemical synthesis method using the nanoparticle size as a parameter has been applied to Sb film-Se particle and Sb film-Te particle systems. In the Sb-Se system, the diffusion of Se atoms to the Sb film can be clearly seen for Se particle sizes less than 50 nm. Diffusion of Sb atoms predominantly took place in the case of the Sb-Te system. The uniqueness of the reaction consists in the diffusion direction of nanoparticles. Comparison with previous work (Kaito et al., 1998b) is made on the basis of the particle stability and electronegativity

  8. Effects of Particle Size on Dilute Particle Dispersion in a Kármán Vortex Street Flow

    Institute of Scientific and Technical Information of China (English)

    武作兵; 凌国灿; 邢启江

    2002-01-01

    It is shown that in a Kármán vortex street flow, particle size influences the dilute particle dispersion. Together with an increase of the particle size, there is an emergence of a period-doubling bifurcation to a chaotic orbit,as well as a decrease of the corresponding basins of attraction. A crisis leads the attractor to escape from the central region of flow. In the motion of dilute particles, a drag term and gravity term dominate and result in a bifurcation phenomenon.

  9. Superselective Particle Embolization Enhances Efficacy of Radiofrequency Ablation: Effects of Particle Size and Sequence of Action

    International Nuclear Information System (INIS)

    Purpose. To evaluate the effects of particle size and course of action of superselective bland transcatheter arterial embolization (TAE) on the efficacy of radiofrequency ablation (RFA). Methods. Twenty pigs were divided into five groups: group 1a, 40-μm bland TAE before RFA; group 1b, 40-μm bland TAE after RFA; group 2a, 250-μm bland TAE before RFA; group 2b, 250-μm bland TAE after RFA and group 3, RFA alone. A total of 40 treatments were performed with a combined CT and angiography system. The sizes of the treated zones were measured from contrast-enhanced CTs on days 1 and 28. Animals were humanely killed, and the treated zones were examined pathologically. Results. There were no complications during procedures and follow-up. The short-axis diameter of the ablation zone in group 1a (mean ± standard deviation, 3.19 ± 0.39 cm) was significantly larger than in group 1b (2.44 ± 0.52 cm; P = 0.021), group 2a (2.51 ± 0.32 cm; P = 0.048), group 2b (2.19 ± 0.44 cm; P = 0.02), and group 3 (1.91 ± 0.55 cm; P 3). At histology, 40-μm microspheres were observed to occlude smaller and more distal arteries than 250-μm microspheres. Conclusion. Bland TAE is more effective before RFA than postablation embolization. The use of very small 40-μm microspheres enhances the efficacy of RFA more than the use of larger particles.

  10. Testosterone sorption and desorption: Effects of soil particle size

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yong, E-mail: yqi01@unomaha.edu [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Zhang, Tian C. [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Ren, Yongzheng [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-08-30

    Graphical abstract: - Highlights: • Smaller soil particles have higher sorption and lower desorption rates. • The sorption capacity ranks as clay > silt > sand. • Small particles like clays have less potential for desorption. • Colloids (clays) have high potential to facilitate the transport of hormones in soil–water environments. - Abstract: Soils contain a wide range of particles of different diameters with different mobility during rainfall events. Effects of soil particles on sorption and desorption behaviors of steroid hormones have not been investigated. In this study, wet sieve washing and repeated sedimentation methods were used to fractionate the soils into five ranges. The sorption and desorption properties and related mechanisms of testosterone in batch reactors filled with fractionated soil particles were evaluated. Results of sorption and desorption kinetics indicate that small soil particles have higher sorption and lower desorption rates than that of big ones. Thermodynamic results show the sorption processes are spontaneous and exothermal. The sorption capacity ranks as clay > silt > sand, depending mainly on specific surface area and surface functional groups. The urea control test shows that hydrogen bonding contributes to testosterone sorption onto clay and silt but not on sand. Desorption tests indicate sorption is 36–65% irreversible from clay to sand. Clays have highest desorption hysteresis among these five soil fractions, indicating small particles like clays have less potential for desorption. The results provide indirect evidence on the colloid (clay)-facilitated transport of hormones (micro-pollutants) in soil environments.

  11. Determination of Size Distribution of Nano-particles by Capillary Zone Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Yan XUE; Hai Ying YANG; Yong Tan YANG

    2005-01-01

    A new method was developed for the determination of the size distribution of nano-particles by capillary zone electrophoresis (CZE). Scattering effect of nanoparticles was studied. This method for the determination of size distribution was statistical.

  12. THE BIMODAL DISTRIBUTION: DEVELOPMENT OF THE CONCEPT OF FINE AND COARSE PARTICLES AS SEPARATE AND DISTINCT COMPONENTS OF AIRBORNE PARTICULATE MATTER

    Science.gov (United States)

    In the early 1970s, it was understood that combustion particles were formed mostly in sizes below 1 um diameter, and windblown dust was suspended in sizes mostly above 1 um diameter. However, particle size distribution was thought of as a single mode. Particles were thought to f...

  13. [Mineral Spectrum Change Analysis under the Conditions of Different Particle Size].

    Science.gov (United States)

    Wang, Yan-xia; Wu, Jian; Zhou, Liang-guang; Hou, Lan-gong; Wang, Dong; Cao, Min

    2015-03-01

    Mineral particle size is an important factor affecting mineral spectrum characteristics, so to explore the changes of the mineral spectrum curves under different particle sizes and the spectrum difference of different minerals under the same particle size are the keys of hyperspectral remote sensing information mineral identification and the theoretical basis of research on spectral differences of different particle -sizes. Six kinds of collected minerals were observed by spectrometer to get the reflectivity spectrum curve and first order differential spectral curve under different particle sizes, and the spectral characteristics of various kinds of minerals under different particle sizes were analyzed. At the same time, spectrum difference of different mineral under the same particle size was compared to explore possible wavelengths of hyperspectral remote sensing mineral identify. Results show that the spectrum curves of various minerals have a larger difference with the change of the particle size, but change law is not the same. The whole spectrum curve of hypersthene will be decreased with the increase of particle size, and the spectrum curve at a specific wavelength range of antigorite, hematite, kaolinite and chlorite will be decreased with the increase of particle size, and there is no direct correlation between the spectrum of olivine and the particle size. Under the same size, different mineral spectral reflectance change a lot in most band range and it provides the possibility for high precision identification of mineral. Antigorite, kaolinite and chlorite all have more absorption peaks of narrow width and smaller intensity than the other minerals. Spectrum curves of hematite, olivine and hypersthene are relatively smooth, and the number of the absorption and reflection peaks is relatively small. This study aims at providing basic data and theoretical support for mineral spectral library construction and mineral hyperspectral identification technology

  14. Characterization of spherical core–shell particles by static light scattering. Estimation of the core- and particle-size distributions

    International Nuclear Information System (INIS)

    A numerical method is proposed for the characterization of core–shell spherical particles from static light scattering (SLS) measurements. The method is able to estimate the core size distribution (CSD) and the particle size distribution (PSD), through the following two-step procedure: (i) the estimation of the bivariate core–particle size distribution (C–PSD), by solving a linear ill-conditioned inverse problem through a generalized Tikhonov regularization strategy, and (ii) the calculation of the CSD and the PSD from the estimated C–PSD. First, the method was evaluated on the basis of several simulated examples, with polystyrene–poly(methyl methacrylate) core–shell particles of different CSDs and PSDs. Then, two samples of hematite–Yttrium basic carbonate core–shell particles were successfully characterized. In all analyzed examples, acceptable estimates of the PSD and the average diameter of the CSD were obtained. Based on the single-scattering Mie theory, the proposed method is an effective tool for characterizing core–shell colloidal particles larger than their Rayleigh limits without requiring any a-priori assumption on the shapes of the size distributions. Under such conditions, the PSDs can always be adequately estimated, while acceptable CSD estimates are obtained when the core/shell particles exhibit either a high optical contrast, or a moderate optical contrast but with a high ‘average core diameter’/‘average particle diameter’ ratio. -- Highlights: ► Particles with core–shell morphology are characterized by static light scattering. ► Core size distribution and particle size distribution are successfully estimated. ► Simulated and experimental examples are used to validate the numerical method. ► The positive effect of a large core/shell optical contrast is investigated. ► No a-priori assumption on the shapes of the size distributions is required.

  15. Mathematical model parameters for describing the particle size spectra of knife-milled corn stover

    Energy Technology Data Exchange (ETDEWEB)

    Bitra, V.S.P [University of Tennessee; Womac, A.R. [University of Tennessee; Yang, Y.T. [University of Tennessee; Miu, P.I. [University of Tennessee; Igathanathane, C. [Mississippi State University (MSU)

    2009-09-01

    Particle size distributions of Corn stover (Zea mays L.) created by a knife mill were determined using integral classifying screens with sizes from 12.7 to 50.8 mm, operating at speeds from 250 to 500 rpm, and mass input rates ranging from 1 to 9 kg min_1. Particle distributions were classified using American Society of Agricultural and Biological Engineers (ASABE) standardised sieves for forage analysis that incorporated a horizontal sieving motion. The sieves were made from machined-aluminium with their thickness proportional to the sieve opening dimensions. A wide range of analytical descriptors that could be used to mathematically represent the range of particle sizes in the distributions were examined. The correlation coefficients between geometric mean length and screen size, feed rate, and speed were 0.980, 0.612, and _0.027, respectively. Screen size and feed rate directly influenced particle size, whereas operating speed had a weak indirect relation with particle size. The Rosin Rammler equation fitted the chopped corn stover size distribution data with coefficient of determination (R2) > 0.978. This indicated that particle size distribution of corn stover was well-fit by the Rosin Rammler function. This can be attributed to the fact that Rosin Rammler expression was well suited to the skewed distribution of particle sizes. Skewed distributions occurred when significant quantities of particles, either finer or coarser, existed or were removed from region of the predominant size. The mass relative span was slightly greater than 1, which indicated that it was a borderline narrow to wide distribution of particle sizes. The uniformity coefficient was <4.0 for 19.0 50.8 mm screens, which indicated particles of relatively uniform size. Knife mill chopping of corn stover produced fine-skewed mesokurtic particles with 12.7 50.8 mm screens. Size-related parameters, namely, geometric mean length, Rosin Rammler size parameter, median length, effective length, and

  16. Effects of fuel particle size distributions on neutron transport in stochastic media

    International Nuclear Information System (INIS)

    Highlights: • Effects of fuel particle size distributions on neutron transport are evaluated. • Neutron channeling is identified as the fundamental reason for the effects. • The effects are noticeable at low packing and low optical thickness systems. • Unit cells of realistic reactor designs are studied for different size particles. • Fuel particle size distribution effects are not negligible in realistic designs. - Abstract: This paper presents a study of the fuel particle size distribution effects on neutron transport in three-dimensional stochastic media. Particle fuel is used in gas-cooled nuclear reactor designs and innovative light water reactor designs loaded with accident tolerant fuel. Due to the design requirements and fuel fabrication limits, the size of fuel particles may not be perfectly constant but instead follows a certain distribution. This brings a fundamental question to the radiation transport computation community: how does the fuel particle size distribution affect the neutron transport in particle fuel systems? To answer this question, size distribution effects and their physical interpretations are investigated by performing a series of neutron transport simulations at different fuel particle size distributions. An eigenvalue problem is simulated in a cylindrical container consisting of fissile fuel particles with five different size distributions: constant, uniform, power, exponential and Gaussian. A total of 15 parametric cases are constructed by altering the fissile particle volume packing fraction and its optical thickness, but keeping the mean chord length of the spherical fuel particle the same at different size distributions. The tallied effective multiplication factor (keff) and the spatial distribution of fission power density along axial and radial directions are compared between different size distributions. At low packing fraction and low optical thickness, the size distribution shows a noticeable effect on neutron

  17. Lung deposition predictions of airborne particles and the emergence of contemporary diseases Part-I

    Directory of Open Access Journals (Sweden)

    Khan A

    2011-05-01

    Full Text Available Inhaled particles can cause a variety of pulmonary illnesses such as asthma, bronchitis, chronic obstructive pulmonary diseases (COPD and even secondary organismic diseases. Thus, predictions of inhaled aerosol deposition in the respiratory tract are essential not only to assess their possible consequences but also to optimize drug delivery using pharmaceutical aerosols. Deposition of inhaled aerosols is a complex phenomenon that depends on the physico-chemical properties of the particles, lung anatomy, and respiratory patterns of the subject. Hence, the prediction of particle deposition for an individual person poses real challenges. Different conceptual particle deposition models are employed for the estimation of deposition fraction in different region of the lung. However, these deposition fractions vary with the above mentioned parameters in addition to the modeling and computational technique. Part-I of this review article briefly describes the deposition behaviour of inhaled particulate matter and the currently available approaches for the prediction of aerosol deposition in the respiratory tract. Part-II continues this thread and provides a broad view of the health-related issues of particle exposure.

  18. Particle Size Distribution and Characterization of High Siliceous and Microporous Materials

    Institute of Scientific and Technical Information of China (English)

    S.K. Durrani; J.Akhtar; M. Ahmad; M.J. Moughal

    2005-01-01

    Particle size, textural and surface characteristics influence some major technological properties of high siliceous aluminosilicate zeolite and sillicoaluminophosphate (SAPO) microporous materials. A comparative study was furnished for measuring surface characteristics, particle size and particle size distribution using particle size analyzer (PSA)and scanning electron microscope (SEM). The PSA is capable of measuring particle diameter in micron range. The results of these techniques for estimation of particle size were compared and correlated statistically. Student t-test and variance ratio test (F-test) methods were performed for the significance of results by the analysis of variance (ANONA) and multiple-range tests. Textural and surface characteristics were evaluated by Brunauer, Emmett &Teller (BET) volumetric technique and v-αs plotting method. The textural results shows that the external surface area and micropore volume of microporous materials were higher than those of the high siliceous zeolites and its zeotype materials.

  19. Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes.

    Science.gov (United States)

    Dalmora, Adilson C; Ramos, Claudete G; Oliveira, Marcos L S; Teixeira, Elba C; Kautzmann, Rubens M; Taffarel, Silvio R; de Brum, Irineu A S; Silva, Luis F O

    2016-01-01

    Understanding the geochemistry of basalt alteration is central to the study of agriculture systems. Various nano-minerals play an important role in the mobilization of contaminants and their subsequent uptake by plants. We present a new analytical experimental approach in combination with an integrated analytical protocol designed to study basalt alteration processes. Recently, throughout the world, ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been of great concern for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the Nova Prata mining district in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/Energy Dispersive Spectroscopy (EDS)/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM/EDS), and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3, and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition, we have identified a number of trace metals such as Cd, Cu, Cr, and Zn, that are preferentially concentrated into the finer, inhalable, dust fraction and, thus, could present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in

  20. Nano-sized Y2O3:Eu phosphor particles prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Y2O3:Eu phosphor particles with nano-sized and non-aggregation characteristics were prepared by spray pyrolysis using spraying solution containing polymeric precursors and Li2CO3 flux material. The post-treated phosphor particles with fine size and high brightness were ball milled to reduce the aggregation degree of the nano-sized Y2O3:Eu phosphor particles. The mean particle size, morphology, and brightness of Y2O3:Eu phosphor particles were strongly affected by contents of the additives and post-treatment temperature. The Y2O3:Eu phosphor particles prepared from the solution containing 0.3 M citric acid, 0.3 M ethylene glycol and 5 wt.% Li2CO3 had fine size and good morphology after post-treatment. The Y2O3:Eu phosphor particles post-treated at 1000 deg. C for 3 h had the mean size of 300 nm. Nano-sized Y2O3:Eu phosphor particles prepared by spray pyrolysis had similar photoluminescence intensity to the micron-sized Y2O3:Eu commercial product prepared by solid state reaction method. The Y2O3:Eu phosphor particles had aggregation-free and regular morphology characteristics even after 30 min ball milling process

  1. Finite size fluid particle in nonuniform moving grid

    International Nuclear Information System (INIS)

    The particle-in-cell (PIC) method, which is known as mixed Eulerian-Lagrangian scheme, has been applied successfully to solve a wide variety of problems in which the fluid distortion is large. In this paper, a new type of the PIC method is presented. Area-weighting technique and a nonuniform-spacing, moving grid were employed for the suppression of nonphysical fluctuation and for the description of large density variation with few particles, respectively. The reduction of numerical viscosity is discussed. In a basic scheme, the equations for one compressible fluid were used. In the present approach to the PIC method, a particle has the memories for its own mass, position and internal energy, but momentum is attached to the particle only when it moves, in order to evade the multistreaming problem. An essential point is that a particle preserves the memory of the cell boundary lines when it moves. As the examples, one-dimensional adiabatic expansion process and the Rayleigh-Taylor instability were analyzed. The results showed that the new PIC method is useful for the description of large density variation with few particles as well as for the cases known to be powerful in Harlow's PIC method. Nonphysical noise, numerical thermal diffusion and viscosity were successfully reduced. A nonuniformly-spacing, moving grid system can be used for the local fine resolution of processes. (Kato, T.)

  2. Particle number size distribution and new particle formation:New characteristics during the special pollution control period in Beijing

    Institute of Scientific and Technical Information of China (English)

    Jian Gao; Fahe Chai; Tao Wang; Shulan Wang; Wenxing Wang

    2012-01-01

    New particle formation is a key process in shaping the size distribution of aerosols in the atmosphere.We present here the measurement results of number and size distribution of aerosol particles (10-10000 nm in diameter) obtained in the summer of 2008,at a suburban site in Beijing,China.We firstly reported the pollution level,particle number size distribution,diurnal variation of the particle number size distribution and then introduced the characteristics of the particle formation processes.The results showed that the number concentration of ultrafine particles was much lower than the values measured in other urban or suburban areas in previous studies.Sharp increases of ultrafine particle count were frequently observed at noon.An examination of the diurnal pattern suggested that the burst of ultrafine particles was mainly due to new particle formation promoted by photochemical processes.In addition,high relative humidity was a key factor driving the growth of the particles in the afternoon.During the 2-month observations,new particle formation from homogeneous nucleation was observed for 42.7% of the study period.The average growth rate of newly formed particles was 3.2 nm/hr,and varied from 1.2 to 8.0 nm/hr.The required concentration of condensable vapor was 4.4 × 107 cm-3,and its source rate was 1.2 × 106 cm-3sec-1.Further calculation on the source rate of sulphuric acid vapor indicated that the average participation of sulphuric acid to particle growth rates was 28.7%.

  3. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

    2015-11-17

    Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

  4. Influence of Particle Size Distribution on Micromechanical Properties of thin Nanoparticulate Coatings

    Science.gov (United States)

    Barth, Nina; Schilde, Carsten; Kwade, Arno

    In this study the production of thin nanoparticulate coatings on solid stainless-steel substrates using dip-coating was investigated. Defined particle sizes and particle size distributions of Al2O3-nanoparticles were adjusted by stirred media milling using various operating parameters. Using nanoindentation the influence of particle size and width of the particle size distribution on the mechanical properties was investigated. In particular the establishment of nanoindentation routines for particulate thin films in contrast to hard coatings is discussed. Nanoindentation appears to be an efficient method for analysing mechanical properties of said thin coatings. It will be shown, that the influence of the substrate can be neglected for small indent depth while the coating's surface roughness influences the employed routine of the nanoindentation. The effect of the median particle size and the width of the particle size distribution on the coating structure and the micromechanical coating properties will be discussed. As a result, the maximum indentation force decreases with decreasing particle size but rises again once the nanoparticles reach very small sizes. A change in the width of the particle size distribution influences the micromechanical properties and coating structure as well.

  5. OPTICAL INSTRUMENT FOR IN-STACK MONITORING OF PARTICLE SIZE

    Science.gov (United States)

    A new light scattering instrument for in-situ measurements of particulates in the 0.2 to 10.0 micrometer diameter size range is described. Two modes of scattering are used, each with two wavelengths of light, to generate five size fractions by volume from a distribution of partic...

  6. Particle size dependent magnetic properties and phase transitions in multiferroic BiFeO{sub 3} nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Annapu Reddy, V., E-mail: reddydph@iitr.ernet.in [Ferroelectric Materials and Devices Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand 247667 (India); Radio Frequency Integrated Circuits Research Laboratory, Department of Electronics and Computer Engineering, Indian Institute of Technology Roorkee, Uttarakhand 247667 (India); Pathak, N.P. [Radio Frequency Integrated Circuits Research Laboratory, Department of Electronics and Computer Engineering, Indian Institute of Technology Roorkee, Uttarakhand 247667 (India); Nath, R., E-mail: rnathfph@iitr.ernet.in [Ferroelectric Materials and Devices Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand 247667 (India)

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer Nano-particles of Bismuth ferrite was synthesized by spray pyrolysis technique at low temperature. Black-Right-Pointing-Pointer Bismuth ferrite exhibits room temperature weak ferromagnetism. Black-Right-Pointing-Pointer The adsorbate induced spin polarization screening in Bismuth ferrite nanoparticles. Black-Right-Pointing-Pointer The superparaelectric size of Bismuth ferrite was determined. Black-Right-Pointing-Pointer The phase transitions shift with particle size are discussed base on the modified Ising model. - Abstract: The particle size effect in the range 10-150 nm on the magnetic properties and phase transitions in BiFeO{sub 3} samples prepared by spray pyrolysis method has been studied. The phase purity and structure have been investigated by XRD and FTIR spectroscopy analysis. The FTIR peaks of the nanoparticles shift to lower wave number due to increase surface area and grain boundaries. The Fe-SEM and TEM images show that the particles are uniform, dense and of nearly spherical shape nanoparticles. The significant enhancement in magnetization with finite coercive field has been observed in 12 nm particle size samples. The increase in magnetization is about four times larger than that of the bulk samples. It has been attributed to the suppression of the cycloidal spin structure due to large uncompensated spins of Fe{sup +3} ions at the surface of the particle and the adsorbate induced spin polarization screening in BFO nanoparticles. The phase transitions above room temperature have been investigated by DTA measurements and show that Neel temperature (T{sub N}) and Curie temperature (T{sub c}) increase with particle size. The shift in T{sub N} and T{sub c} values with particle size are fitted well to the finite scaling models. The microscopic parameters like correction length, characteristic microscopic dimension of the system and critical particle size have been evaluated which provide more physical insight in

  7. Particle size dependent magnetic properties and phase transitions in multiferroic BiFeO3 nano-particles

    International Nuclear Information System (INIS)

    Highlights: ► Nano-particles of Bismuth ferrite was synthesized by spray pyrolysis technique at low temperature. ► Bismuth ferrite exhibits room temperature weak ferromagnetism. ► The adsorbate induced spin polarization screening in Bismuth ferrite nanoparticles. ► The superparaelectric size of Bismuth ferrite was determined. ► The phase transitions shift with particle size are discussed base on the modified Ising model. - Abstract: The particle size effect in the range 10–150 nm on the magnetic properties and phase transitions in BiFeO3 samples prepared by spray pyrolysis method has been studied. The phase purity and structure have been investigated by XRD and FTIR spectroscopy analysis. The FTIR peaks of the nanoparticles shift to lower wave number due to increase surface area and grain boundaries. The Fe-SEM and TEM images show that the particles are uniform, dense and of nearly spherical shape nanoparticles. The significant enhancement in magnetization with finite coercive field has been observed in 12 nm particle size samples. The increase in magnetization is about four times larger than that of the bulk samples. It has been attributed to the suppression of the cycloidal spin structure due to large uncompensated spins of Fe+3 ions at the surface of the particle and the adsorbate induced spin polarization screening in BFO nanoparticles. The phase transitions above room temperature have been investigated by DTA measurements and show that Néel temperature (TN) and Curie temperature (Tc) increase with particle size. The shift in TN and Tc values with particle size are fitted well to the finite scaling models. The microscopic parameters like correction length, characteristic microscopic dimension of the system and critical particle size have been evaluated which provide more physical insight in the finite scaling effect in the nanoparticle samples.

  8. Particle Sampling and Real Time Size Distribution Measurement in H2/O2/TEOS Diffusion Flame

    International Nuclear Information System (INIS)

    Growth characteristics of silica particles have been studied experimentally using in situ particle sampling technique from H2/O2/Tetraethylorthosilicate (TEOS) diffusion flame with carefully devised sampling probe. The particle morphology and the size comparisons are made between the particles sampled by the local thermophoretic method from the inside of the flame and by the electrostatic collector sampling method after the dilution sampling probe. The Transmission Electron Microscope (TEM) image processed data of these two sampling techniques are compared with Scanning Mobility Particle Sizer (SMPS) measurement. TEM image analysis of two sampling methods showed a good agreement with SMPS measurement. The effects of flame conditions and TEOS flow rates on silica particle size distributions are also investigated using the new particle dilution sampling probe. It is found that the particle size distribution characteristics and morphology are mostly governed by the coagulation process and sintering process in the flame. As the flame temperature increases, the effect of coalescence or sintering becomes an important particle growth mechanism which reduces the coagulation process. However, if the flame temperature is not high enough to sinter the aggregated particles then the coagulation process is a dominant particle growth mechanism. In a certain flame condition a secondary particle formation is observed which results in a bimodal particle size distribution

  9. Effect of Particle Size and Grinding Time on Gold Dissolution in Cyanide Solution

    Directory of Open Access Journals (Sweden)

    Jessica Egan

    2016-07-01

    Full Text Available The recovery of gold by ore leaching is influenced by the size of the particles and the chemical environment. The effect of particle size on the dissolution of gold is usually studied using mono-size particles as the gold in solution comes from the ore of a unique leached particle size. This paper proposes a method to estimate the gold dissolution as a function of particle size using a bulk ore sample, i.e., with the dissolved gold coming from the various sizes of particles carried by the ore. The results are consistent with the fact that gold dissolution increases with the decreasing particle size but results also indicate that gold dissolution of the ore within a size interval is not significantly affected by the grinding time used for the ore size reduction. Results also show a good dissolution of the gold contained in the fine-size fractions without oxidation and lead nitrate pre-treatment for an ore that is known to require such pre-treatment.

  10. Particle size distribution measurements of manganese-doped ZnS nanoparticles.

    Science.gov (United States)

    Dieckmann, Yvonne; Cölfen, Helmut; Hofmann, Heinrich; Petri-Fink, Alke

    2009-05-15

    We performed particle size and particle size distribution measurements for L-cysteine-stabilized ZnS/Mn nanoparticles in the size region below 10 nm. For this we applied transmission electron microscopy (TEM), analytical ultracentrifugation (AUC), dynamic light scattering (DLS), and asymmetric flow field flow fractionation (aF-FFF) measurements, and we calculated particle sizes with the help of X-ray diffraction (XRD) patterns and the shift of the band gap absorption in the UV-vis spectrum. The different methods are explained, and their limitations are discussed, with the conclusion that only a combination of different techniques can yield a realistic and complete picture about the size distribution of the sample. From these methods TEM, AUC, DLS, and aF-FFF measure the actual particle size distribution either in dispersion or after drying of the sample, whereas the particle size obtained from XRD patterns and with the help of the band gap widening corresponds to the average size of the crystal domains within the particles. We obtained particle size distributions with their maximum between 3 and 7 nm and a mean crystallite size of 3.5-4 nm. PMID:19374425

  11. Indoor and outdoor airborne particles. An in vitro study on mutagenic potential and toxicological implications.

    NARCIS (Netherlands)

    Houdt, van J.J.

    1988-01-01

    IntroductionAir pollution components are present as gases and as particulate matter. As particle deposition takes place in various parts of the respiratory system particulate matter may have other toxicological implications than gaseous pollutants, which all may penetrate in the low

  12. Effect of atmospheric electricity on dry deposition of airborne particles from atmosphere

    Science.gov (United States)

    Tammet, H.; Kimmel, V.; Israelsson, S.

    The electric mechanism of dry deposition is well known in the case of unattached radon daughter clusters that are unipolar charged and of high mobility. The problematic role of the electric forces in deposition of aerosol particles is theoretically examined by comparing the fluxes of particles carried by different deposition mechanisms in a model situation. The electric mechanism of deposition appears essential for particles of diameter 10-200 nm in conditions of low wind speed. The electric flux of fine particles can be dominant on the tips of leaves and needles even in a moderate atmospheric electric field of a few hundred V m -1 measured over the plane ground surface. The electric deposition is enhanced under thunderclouds and high voltage power lines. Strong wind suppresses the relative role of the electric deposition when compared with aerodynamic deposition. When compared with diffusion deposition the electric deposition appears less uniform: the precipitation particulate matter on the tips of leaves and especially on needles of top branches of conifer trees is much more intensive than on the ground surface and electrically shielded surfaces of plants. The knowledge of deposition geometry could improve our understanding of air pollution damage to plants.

  13. Aerobyologic monitoring in urban and extra urban areas : analysis of airborne fungal particle concentration; Indagini aerobiologiche in ambiente urbano ed extraurbano componente fungina aerodiffusa

    Energy Technology Data Exchange (ETDEWEB)

    Bari, A. [ENEA, Saluggia (Italy). Centro Ricerche Energia; Caramiello, R.; Fossa, V.; Potenza, A. [Turin Univ. (Italy), Dip. di Biologia Vegetale

    1995-12-01

    In the environmental monitoring studies carried out by ENEA (Italian Agency for New Technologies, Energy and the Environment) a research about air quality of Turin and Saluggia (VC) has started in collaboration with the University of Turin. This research concerns the study of pollen and airborne fungal particle concentrations in the atmosphere. In the last few years the interest in airborne spores and hyphal fragments has increased. Indeed these particles play a very important role in allergic reactions, in several other human diseases, and in plant pathology. The incidence and the risk of infections by airborne fungal spores are correlated to the general climate and to the local micro climatic conditions; a complete aerosporological knowledge can be in many cases a useful indicator for infection risks. In this study the concentrations of airborne fungal spores in two different stations (urban station, Turin; and rural station, Saluggia (VC)) has been evaluated and compared, only for the year 1992, in order to verify the influence of climatic conditions and of floristic and vegetational aspects. In order to establish the correlations between the climate and the airborne fungal data, the results of aerosporogical analysis, relative to the Turin station, are reported. This investigation cover a six year period, three of which under standard climatic conditions and three with considerable peculiarities. A comparative evaluation of the efficiency in the collection of aerobiological particles (pollen and spores) by natural traps (mosses) has been attempted in Saluggia. The results obtained by this palinological analysis have been compared with the composition of the local flora and the data monitored by a spore-trap (volumetric pollen trap) positioned on the roof of a building in the ENEA Research Center of Saluggia.

  14. Airborne measurements of trace gas and aerosol particle emissions from biomass burning in Amazonia

    Directory of Open Access Journals (Sweden)

    P. Guyon

    2005-05-01

    Full Text Available As part of the LBA-SMOCC (Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke, Aerosols, Clouds, Rainfall, and Climate 2002 campaign, we studied the emission of carbon monoxide (CO, carbon dioxide (CO2, and aerosol particles from Amazonian deforestation fires using an instrumented aircraft. Emission ratios for aerosol number (CN relative to CO (ERCN/CO fell in the range 14–32 cm-3 ppb-1 for most of the time, in agreement with values usually found from tropical savanna fires. The number of particles emitted per amount biomass burned was found to be dependant on the fire condition (combustion efficiency. Variability in the ERCN/CO between fires was similar to the variability caused by variations in combustion behavior within each individual fire. This was confirmed by observations of CO-to-CO2 emission ratios (ERCO/CO2, which stretched across the same wide range of values for individual fires as for all the fires observed during the sampling campaign, indicating that flaming and smoldering phases are present simultaneously in deforestation fires. Emission factors (EF for CO and aerosol particles were computed and a correction was applied for the residual smoldering combustion (RSC fraction of emissions that are not sampled by the aircraft. The correction, previously unpublished for tropical deforestation fires, suggested an EF about one and a half to twice as large for these species. Vertical transport of biomass-burning plumes from the boundary layer (BL to the cloud detrainment layer (CDL and the free troposphere (FT was found to be a very common phenomenon. We observed a 20% loss in particle number as a result of this vertical transport and subsequent cloud processing, attributable to in-cloud coagulation. This small loss fraction suggests that this mode of transport is very efficient in terms of particle numbers and occurs mostly via non

  15. Airborne measurements of trace gas and aerosol particle emissions from biomass burning in Amazonia

    Directory of Open Access Journals (Sweden)

    P. Guyon

    2005-01-01

    Full Text Available As part of the LBA-SMOCC (Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Smoke, Aerosols, Clouds, Rainfall, and Climate 2002 campaign, we studied the emission of carbon monoxide (CO, carbon dioxide (CO2, and aerosol particles from Amazonian deforestation fires using an instrumented aircraft. Emission ratios for aerosol number (CN relative to CO (ERCN/CO fell in the range 14-32 cm-3 ppb-1 in most of the investigated smoke plumes. Particle number emission ratios have to our knowledge not been previously measured in tropical deforestation fires, but our results are in agreement with values usually found from tropical savanna fires. The number of particles emitted per amount biomass burned was found to be dependent on the fire conditions (combustion efficiency. Variability in ERCN/CO between fires was similar to the variability caused by variations in combustion behavior within each individual fire. This was confirmed by observations of CO-to-CO2 emission ratios (ERCO/CO2, which stretched across the same wide range of values for individual fires as for all the fires observed during the sampling campaign, reflecting the fact that flaming and smoldering phases are present simultaneously in deforestation fires. Emission factors (EF for CO and aerosol particles were computed and a correction was applied for the residual smoldering combustion (RSC fraction of emissions that are not sampled by the aircraft, which increased the EF by a factor of 1.5-2.1. Vertical transport of smoke from the boundary layer (BL to the cloud detrainment layer (CDL and the free troposphere (FT was found to be a very common phenomenon. We observed a 20% loss in particle number as a result of this vertical transport and subsequent cloud processing, attributable to in-cloud coagulation. This small loss fraction suggests that this mode of transport is very efficient in terms of particle numbers and occurs mostly via non-precipitating clouds. The detrained aerosol

  16. Heterogeneous reaction of N2O5 with airborne TiO2 particles and the implication for stratospheric particle injection

    Science.gov (United States)

    Tang, Mingjin; Abraham, Luke; Braesicke, Peter; Cox, Tony; McGregor, James; Pope, Francis; Pyle, John; Rkiouak, Laylla; Telford, Paul; Watson, Matt; Kalberer, Markus

    2014-05-01

    Injection of aerosol particles (or their precursors) into the stratosphere to scatter solar radiation back into space, has been suggested as a solar-radiation management (SRM) scheme for the mitigation for global warming. TiO2 has recently been highlighted as a possible candidate aerosol because of its high light scattering ability with a refractive index of 2.5 (Pope et al. 2012). The impact of particles injection on stratospheric ozone requires systematical assessment via laboratory and modelling studies. In this work, the heterogeneous reaction of airborne sub-micrometre TiO2 particles with N2O5 has been investigated at room temperature and different relative humidities (RH), using an atmospheric pressure aerosol flow tube. The uptake coefficient of N2O5 onto TiO2, γ(N2O5), was determined to be ~1.0×10-3 at low RH, and increase to ~3×10-3 at 60% RH. The dependence of γ(N2O5) on RH can be explained by the water adsorption isotherm of TiO2 particles. In addition, the uptake of N2O5 onto TiO2 aerosol particles has been included in the UKCA chemistry-climate model to assess the effect of N2O5 uptake onto TiO2 particles on the stratospheric composition. We construct a case study based on the eruption of Mt. Pinatubo, comparing the effects of TiO2 to those from the volcanic sulfate and to the situation with only background amount of aerosol. The changes in reactive nitrogen species and ozone due to the heterogeneous reaction of TiO2 with N2O5 are assessed relative to sulfate aerosol impacts. Pope, F. D., Braesicke, P., Grainger, R. G., Kalberer, M., Watson, I. M., Davidson, P. J., and Cox, R. A.: Stratospheric aerosol particles and solar-radiation management, Nature Clim. Change, 2, 713-719, 2012

  17. Particle size effects in Fischer-Tropsch synthesis by Co catalyst supported on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Ali Nakhaei Pour; Elham Hosaini; Mohammad Izadyar; Mohammad Reza Housaindokht

    2015-01-01

    The effect of Co particle size on the Fischer-Tropsch synthesis (FTS) activity of carbon nanotube (CNT)-supported Co catalysts was investigated. Microemulsion (using water-to-surfactant molar ratios of 2 to12) and impregnation techniques were used to prepare catalysts with different Co particle sizes. Kinetic studies were performed to understand the effect of Co particle size on catalytic activity. Size-dependent kinetic parameters were developed using a thermodynamic method, to evaluate the structural sensitivity of the CNT-supported Co catalysts. The size-independent FTS reaction rate constant and size-independent adsorption parameter increased with increasing reac-tion temperature. The Polani parameter also depended on catalyst particle size, because of changes in the catalyst surface coverage.

  18. Seasonal Variations of Number Size Distributions and Mass Concentrations of Atmospheric Particles in Beijing

    Institute of Scientific and Technical Information of China (English)

    YU Jianhua; Benjamin GUINOT; YU Tong; WANG Xin; LIU Wenqing

    2005-01-01

    Particle number and mass concentrations were measured in Beijing during the winter and summer periods in 2003, together with some other parameters including black carbon (BC) and meteorological conditions. Particle mass concentrations exhibited low seasonality, and the ratio of PM2.5/PM10 in winter was higher than that in summer. Particle number size distribution (PSD) was characterized by four modes and exhibited low seasonality. BC was well correlated with the number and mass concentrations of accumulation and coarse particles, indicating these size particles are related to anthropogenic activities.Particle mass and number concentrations (except ultra-fine and nucleation particles) followed well the trends of BC concentration for the majority of the day, indicating that most particles were associated with primary emissions. The diurnal number distributions of accumulation and coarse mode particles were characterized by two peaks.

  19. Particle-size distribution and gas/particle partitioning of atmospheric polybrominated diphenyl ethers in urban areas of Greece

    Energy Technology Data Exchange (ETDEWEB)

    Mandalakis, Manolis; Besis, Athanasios [Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, GR-71003 Heraklion-Voutes (Greece); Stephanou, Euripides G. [Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, GR-71003 Heraklion-Voutes (Greece)], E-mail: stephanou@chemistry.uoc.gr

    2009-04-15

    Ambient concentrations, gas/particle partitioning and particle-size distribution of polybrominated diphenyl ethers (PBDEs) were investigated in two urban areas (Athens and Heraklion) of Greece. Atmospheric (gas + particle) concentrations of {sigma}PBDE varied from 21 to 30 pg m{sup -3} in the center of Athens and from 4 to 44 pg m{sup -3} in the suburbs of Heraklion. A predominance of particulate PBDEs was observed in Athens (71-76% in particles), whereas the opposite was evident in Heraklion (69-92% in gas phase). In both urban areas, PBDE particle-size distribution featured a distinct enrichment in smaller particles. A similar trend was also observed in aerosols of a background marine site. For all sampling sites, more than 46% of {sigma}PBDE was associated with particles of <0.57 {mu}m in diameter. Our results imply that particulate PBDEs may have long atmospheric residence time and they may be capable of reaching the deeper parts of the human respiratory system. - Analysis of size-segregated aerosol samples indicates a predominance of polybrominated diphenyl ethers in the small particle-size fraction.

  20. Effect of particle size on microstructure and mechanical properties of composites produced by ARB process

    International Nuclear Information System (INIS)

    Research highlights: → Microstructure of MMC with larger particles becomes completely uniform, sooner. → When the number of cycles increased, tensile strength for both samples improved. → Up to the seventh cycle, tensile strength of MMC with larger particles was bigger. → First, the tensile elongation of MMCs was decreased, and then it was improved. - Abstract: In the present work, Al/10 vol.% SiC metal matrix composite (MMC) was manufactured by accumulative roll bonding (ARB) process. The silicon carbide particles with two various particle sizes of 40 and 2 μm were used. Effect of particle size on microstructure (by scanning electron microscopy) and mechanical properties (tensile strength and elongation) at various ARB cycles was investigated. It was found that the microstructural evolution in MMC with 40 μm particle size was more salient compared to the MMCs with 2 μm particle size. Also, the composite strip with 40 μm particle size became uniform with high bonding quality and without any porosity sooner than the strip of 2 μm particle size. Moreover, when the number of cycles was increased, the tensile strength for both samples was improved. The tensile strength of the composite strip with 40 μm particle size was more than the composite strip with 2 μm up to the seventh cycle. By increasing the number of cycles after the seventh cycle, the value of tensile strength of MMC with 40 μm particle size became saturated and then decreased, and its tensile strength became less than that of the composite with 2 μm particle size for the ninth and eleventh cycles. Up to the seventh cycle, when the number of ARB cycles was increased, the elongation of composite strips was decreased, but after the ninth cycle, the tensile elongation for both samples was improved.

  1. Effect of particle size on microstructure and mechanical properties of composites produced by ARB process

    Energy Technology Data Exchange (ETDEWEB)

    Jamaati, Roohollah, E-mail: r.jamaatikenari@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Amirkhanlou, Sajjad; Toroghinejad, Mohammad Reza; Niroumand, Behzad [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2011-02-25

    Research highlights: {yields} Microstructure of MMC with larger particles becomes completely uniform, sooner. {yields} When the number of cycles increased, tensile strength for both samples improved. {yields} Up to the seventh cycle, tensile strength of MMC with larger particles was bigger. {yields} First, the tensile elongation of MMCs was decreased, and then it was improved. - Abstract: In the present work, Al/10 vol.% SiC metal matrix composite (MMC) was manufactured by accumulative roll bonding (ARB) process. The silicon carbide particles with two various particle sizes of 40 and 2 {mu}m were used. Effect of particle size on microstructure (by scanning electron microscopy) and mechanical properties (tensile strength and elongation) at various ARB cycles was investigated. It was found that the microstructural evolution in MMC with 40 {mu}m particle size was more salient compared to the MMCs with 2 {mu}m particle size. Also, the composite strip with 40 {mu}m particle size became uniform with high bonding quality and without any porosity sooner than the strip of 2 {mu}m particle size. Moreover, when the number of cycles was increased, the tensile strength for both samples was improved. The tensile strength of the composite strip with 40 {mu}m particle size was more than the composite strip with 2 {mu}m up to the seventh cycle. By increasing the number of cycles after the seventh cycle, the value of tensile strength of MMC with 40 {mu}m particle size became saturated and then decreased, and its tensile strength became less than that of the composite with 2 {mu}m particle size for the ninth and eleventh cycles. Up to the seventh cycle, when the number of ARB cycles was increased, the elongation of composite strips was decreased, but after the ninth cycle, the tensile elongation for both samples was improved.

  2. Metal uptake by corn grown on media treated with particle-size fractionated biosolids

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Weiping [Department of Environmental Sciences, University of California, Riverside, CA 92521 (United States)], E-mail: chenweip@yahoo.com.cn; Chang, Andrew C.; Wu, Laosheng [Department of Environmental Sciences, University of California, Riverside, CA 92521 (United States); Zhang, Yongsong [School of Environmental and Natural Resources Sciences, Zhejiang University, Hangzhou, Zhejiang, 31009 (China)

    2008-03-15

    Particle-size of biosolids may affect plant uptake of heavy metals when the biosolids are land applied. In this study, corn (Zea mays L.) was grown on sand media treated with biosolids to study how particle-size of biosolids affected the plant uptake of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Two biosolids, the Nu-Earth biosolids and the Los Angeles biosolids, of dissimilar surface morphology were utilized. The former exhibited a porous and spongy structure and had considerably greater specific surface area than that of the latter, which was granular and blocky. The specific surface area of the Los Angeles biosolids was inversely proportional to its particle-size, while that of Nu-Earth biosolids did not change significantly with particle-size. For each biosolid, the metal concentrations were not affected by particle sizes. The biomass yields of plants grown on the treated media increased as the biosolid particle-size decreased, indicating that plant uptake of nutrients from biosolids was dependent on interactions at the root-biosolids interface. The effect of particle-size on a metal's availability to plants was element-specific. The uptake rate of Cd, Zn, Cu, and Ni was correlated with the surface area of the particles, i.e., smaller particles having higher specific area provided greater root-biosolids contact and resulted in enhanced uptake of Cd and Zn and slightly less increased uptake of Cu and Ni. The particle morphology of biosolids had limited influence on the plant tissue concentrations of Cr and Pb. For both types of biosolids, total metal uptake increased as biosolid particle-size decreased. Our research indicates that biosolid particle-size distribution plays a deciding role in plant uptake of heavy metals when they are land applied.

  3. Experimental determination of the steady-state charging probabilities and particle size conservation in non-radioactive and radioactive bipolar aerosol chargers in the size range of 5–40 nm

    International Nuclear Information System (INIS)

    Three bipolar aerosol chargers, an AC-corona (Electrical Ionizer 1090, MSP Corp.), a soft X-ray (Advanced Aerosol Neutralizer 3087, TSI Inc.), and an α-radiation-based 241Am charger (tapcon & analysesysteme), were investigated on their charging performance of airborne nanoparticles. The charging probabilities for negatively and positively charged particles and the particle size conservation were measured in the diameter range of 5–40 nm using sucrose nanoparticles. Chargers were operated under various flow conditions in the range of 0.6–5.0 liters per minute. For particular experimental conditions, some deviations from the chosen theoretical model were found for all chargers. For very small particle sizes, the AC-corona charger showed particle losses at low flow rates and did not reach steady-state charge equilibrium at high flow rates. However, for all chargers, operating conditions were identified where the bipolar charge equilibrium was achieved. Practically, excellent particle size conservation was found for all three chargers

  4. The influence of particle size on the rheological properties of plate-like iron particle based magnetorheological fluids

    International Nuclear Information System (INIS)

    This work is devoted to the dependence of particle size on magnetorheological properties of magnetorheological fluid (MRF) consisting of plate-like iron particles suspended in a carrier liquid with two aspects. One aspect is to study the influence of the particle size on the rheological properties of the MRF, and the other is to investigate the influence of small-sized particles on the large-sized MRF. In order to achieve this goal, firstly, two different types of MR suspensions have been constituted by a plate-like iron particle; one is small with an average particle size of 2 μm in diameter, and the other is large with an average particle size of 19 μm in diameter. In this work, these are denoted as S-MRF and L-MRF, respectively. Secondly, in order to check the influence of the small particle size of the large-sized MR fluid, three different weight fractions of bidisperse MRF samples are prepared. The structural and morphology of plate-like iron particles are described in detail. The magnetic properties of these MR fluids are carried out at room temperature using the magnetometer, followed by the investigation on the field-dependent rheological properties of these MR fluids. It is observed that in both the S-MRF and L-MRF, the yield stress and viscosity is increased by the increasing particle size, which directly shows a correlation with the fluid magnetization. It is also identified from the test of the bidisperse MRF samples that the yield and viscosity depend on the weight fraction due to the magnetostatic interaction between the two different sizes of particles. Based on the rheological properties, some figures of merit are derived for the proposed MRF samples, which are important in the design of the application device. The sedimentation experiments for MRF samples are performed to check the stability of the MRF each day. With the basic rheological properties and sedimentation experiments, it is clearly demonstrated that the bidisperse MR suspension with a

  5. Effect of particle size on laser-induced breakdown spectroscopy analysis of alumina suspension in liquids

    International Nuclear Information System (INIS)

    The analysis by Laser Induced Breakdown Spectroscopy (LIBS) was proposed for the detection and the quantification of different elements in water even when the analyte is composed of particles in suspension. We have studied the effect of particle size on the LIBS signal during liquid analysis. In our study we used different particle sizes (from 2 μm to 90 μm) of Al2O3 in suspension in water. The results were compared to the signal obtained in the case of dissolved aluminum. In the case of particles, a linear correlation between the LIBS signal versus concentration was found but a significant decrease in the slope of the calibration curve was found when the particle size increased. Several hypotheses have been tested and only a partial ablation of the particles might explain this decrease in signal intensity. This effect probably does not occur at smaller particle size. We estimated 860 nm/pulse as ablated thickness from the top of the particle. A statistical analysis over all data obtained allowed us to calculate 100 μm as ablated water column depth. - Highlights: ► We have identified a decrease of calibration curve when particle size increases. ► Partial particle ablation has been identified as the origin of this effect. ► The ablation rate on Al2O3 particles in suspension in water has been estimated. ► We can determine the deepness of the interaction volume into the liquid.

  6. Facile route to silver submicron-sized particles and their catalytic activity towards 4-nitrophenol reduction

    International Nuclear Information System (INIS)

    Research highlights: → Submicron-sized Ag particles can be prepared by using EDTA as a reducing agent. → By varying the amount of EDTA, the size of Ag particles can be controlled. → By varying the hydrothermal reaction time, the size of Ag particles can be controlled. → In comparison with Ag nanoparticles, the submicron-sized Ag particles have a comparable catalytic activity. - Abstract: A facile, efficient, and environmentally friendly synthetic route was developed to fabricate silver submicron-sized particles by reducing silver nitrate with EDTA in aqueous solution. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) analysis revealed the formation of silver particles, with sizes ranging from 100 to 800 nm. By varying the amount of EDTA utilized in the reaction medium and/or hydrothermal reaction time, the size of prepared silver particles can be readily controlled. Compared with silver nanoparticles, the as-synthesized submicron-sized silver particles were found to show a comparable catalytic activity towards the reduction of 4-nitrophenol to 4-aminophenol in the presence of an excess amount of NaBH4.

  7. Facile route to silver submicron-sized particles and their catalytic activity towards 4-nitrophenol reduction

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Deli [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Xie Jimin, E-mail: Xiejm391@sohu.com [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Chen Min; Li Di; Zhu Jianjun; Qin Huiru [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2011-02-03

    Research highlights: > Submicron-sized Ag particles can be prepared by using EDTA as a reducing agent. > By varying the amount of EDTA, the size of Ag particles can be controlled. > By varying the hydrothermal reaction time, the size of Ag particles can be controlled. > In comparison with Ag nanoparticles, the submicron-sized Ag particles have a comparable catalytic activity. - Abstract: A facile, efficient, and environmentally friendly synthetic route was developed to fabricate silver submicron-sized particles by reducing silver nitrate with EDTA in aqueous solution. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) analysis revealed the formation of silver particles, with sizes ranging from 100 to 800 nm. By varying the amount of EDTA utilized in the reaction medium and/or hydrothermal reaction time, the size of prepared silver particles can be readily controlled. Compared with silver nanoparticles, the as-synthesized submicron-sized silver particles were found to show a comparable catalytic activity towards the reduction of 4-nitrophenol to 4-aminophenol in the presence of an excess amount of NaBH{sub 4}.

  8. Nitrogen mineralization and denitrification as influenced by crop residue particle size

    DEFF Research Database (Denmark)

    Ambus, P.; Jensen, E.S.

    1997-01-01

    Managing the crop residue particle size has the potential to affect N conservation in agricultural systems. We investigated the influence of barley (Hordeum vulgare) and pea (Pisum sativum) crop residue particle size on N mineralization and denitrification in two laboratory experiments. Experiment...

  9. Use of a magnetic fluid for particle size analysis by a sedimentation method

    OpenAIRE

    Dikansky, Yury; Zakinyan, Arthur; Bedganian, Marita

    2011-01-01

    Available at http://arxiv.org/abs/1104.0318v1 International audience A new method of particle size analysis of micrometer-sized particles is discussed. The improved method of sedimentation analysis with magnetic fluids has the potential and versatility to characterize polydisperse systems.

  10. Optical sensor technology for simultaneous measurement of particle speed and concentration of micro sized particles

    DEFF Research Database (Denmark)

    Clausen, Casper; Han, Anpan; Kristensen, Martin;

    2013-01-01

    as a hybrid between Laser Doppler Velocimetry and Laser Particle Counters. The experimental characterization of a lab-scale setup has been performed with polystyrene particles in the range from 750 nm to 20 μm, with various particle speeds. It is shown that particle concentrations can be determined...... independently from particle speeds and is a key advantage compared to normal Laser Particle Counters.......Experimental characterization of a sensor technology that can measure particle speed and concentration simultaneously in liquids and gases is presented here. The basic sensor principle is based on an optical element that shapes a light beam into well-defined fringes. The technology can be described...

  11. Characterization of energy barrier and particle size distribution of lyophilized ferrofluids by magnetic relaxation measurements

    International Nuclear Information System (INIS)

    The magnetic properties of a ferrofluid are strongly influenced by its particle size distribution. We analyzed a ferrofluid with an unknown particle size distribution as well as fractionated samples of the original material. The ferrofluid in our investigations consists of a mixture of maghemite and magnetite. We investigated these different samples using temperature-dependent magnetorelaxometry method. The evaluation of the Neel relaxation signal allows us a direct determination of the energy barrier distribution, which is one of the most important parameters of such systems of magnetic nanoparticles. The calculated particle volumes were compared with particle sizes determined by transmission electron microscopy

  12. Characterization of energy barrier and particle size distribution of lyophilized ferrofluids by magnetic relaxation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Schmidl, Frank [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany)]. E-mail: Frank.Schmidl@uni-jena.de; Weber, Peter [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Koettig, Torsten [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Buettner, Markus [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Prass, Stefan [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Becker, Christoph [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Mans, Michael [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Heinrich, Jochen [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Roeder, Michael [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Wagner, Kerstin [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Berkov, Dimitr V. [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Goernert, Peter [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Gloeckl, Gunnar [Institute of Pharmacy, Ernst-Moritz-Arndt-University, D-17487 Greifswald (Germany); Weitschies, Werner [Institute of Pharmacy, Ernst-Moritz-Arndt-University, D-17487 Greifswald (Germany); Seidel, Paul [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany)

    2007-04-15

    The magnetic properties of a ferrofluid are strongly influenced by its particle size distribution. We analyzed a ferrofluid with an unknown particle size distribution as well as fractionated samples of the original material. The ferrofluid in our investigations consists of a mixture of maghemite and magnetite. We investigated these different samples using temperature-dependent magnetorelaxometry method. The evaluation of the Neel relaxation signal allows us a direct determination of the energy barrier distribution, which is one of the most important parameters of such systems of magnetic nanoparticles. The calculated particle volumes were compared with particle sizes determined by transmission electron microscopy.

  13. Resolving particle size modality in bi-modal iron oxide nanoparticle suspensions

    International Nuclear Information System (INIS)

    Particle size modality in bi-modal iron oxide suspensions was resolved by exploiting complex ac-susceptibility (ACS), small angle X-ray scattering (SAXS) and photon cross-correlation spectroscopy. To explain dynamic magnetic response of bi-modal suspensions, the Debye model was expanded to a linear superposition form allowing for the contribution of both particle fractions. This modified and adopted model is able to resolve the bi-modal particle size distributions. The SAXS curves of mono- and bi-modal suspensions were fitted well using a Monte Carlo simulation scheme, allowing the detection of bi-modal particle size distributions with high precision

  14. Size-resolved fluxes of sub-100-nm particles over forests

    DEFF Research Database (Denmark)

    Pryor, Sara; Barthelmie, Rebecca Jane; Spaulding, A.M.;

    2009-01-01

    Dry deposition of atmospheric particles is critically dependent on particle size and plays a key role in dictating the mass and number distributions of atmospheric particles. However, modeling dry deposition is constrained by a lack of understanding of controlling dependencies and accurate size...... deposition model designed for broadleaf forest exhibits greater accord with the measurements than two previous analytical models, but modeled v d + underestimate observed values by at least a factor of two for all Dp between 6 and 100 nm. When size-resolved particle deposition velocities for Dp ... deposition velocities over forests that could reasonably be applied in regional and global atmospheric chemistry transport models....

  15. Measurement of Soluble and Total Hexavalent Chromium in the Ambient Airborne Particles in New Jersey

    Science.gov (United States)

    Huang, Lihui; Yu, Chang Ho; Hopke, Philip K.; Lioy, Paul J.; Buckley, Brian T.; Shin, Jin Young; Fan, Zhihua (Tina)

    2015-01-01

    Hexavalent chromium (Cr(VI)) in ambient airborne particulate matter (PM) is a known pulmonary carcinogen and may have both soluble and insoluble forms. The sum of the two forms is defined as total Cr(VI). Currently, there were no methods suitable for large-scale monitoring of total Cr(VI) in ambient PM. This study developed a method to measure total Cr(VI) in ambient PM. This method includes PM collection using a Teflon filter, microwave extraction with 3% Na2CO3-2% NaOH at 95°C for 60 minutes, and Cr(VI) analysis by 1,5-diphenylcarbazide colorimetry at 540 nm. The recoveries of total Cr(VI) were 119.5 ± 10.4% and 106.3 ± 16.7% for the Cr(VI)-certified reference materials, SQC 012 and SRM 2700, respectively. Total Cr(VI) in the reference urban PM (NIST 1648a) was 26.0 ± 3.1 mg/kg (%CV = 11.9%) determined by this method. The method detection limit was 0.33 ng/m3. This method and the one previously developed to measure ambient Cr(VI), which is soluble in pH ~9.0 aqueous solution, were applied to measure Cr(VI) in ambient PM10 collected from three urban areas and one suburban area in New Jersey. The total Cr(VI) concentrations were 1.05–1.41 ng/m3 in the winter and 0.99–1.56 ng/m3 in the summer. The soluble Cr(VI) concentrations were 0.03–0.19 ng/m3 in the winter and 0.12–0.37 ng/m3 in the summer. The summer mean ratios of soluble to total Cr(VI) were 14.3–43.7%, significantly higher than 4.2–14.4% in the winter. The winter concentrations of soluble and total Cr(VI) in the suburban area were significantly lower than in the three urban areas. The results suggested that formation of Cr(VI) via atmospheric chemistry may contribute to the higher soluble Cr(VI) concentrations in the summer. PMID:26120324

  16. TOF-SIMS measurements for toxic air pollutants adsorbed on the surface of airborne particles

    Science.gov (United States)

    Tomiyasu, Bunbunoshin; Hoshi, Takahiro; Owari, Masanori; Nihei, Yoshimasa

    2003-01-01

    Three kinds of particulate matter were collected: diesel and gasoline exhaust particles emitted directly from exhaust nozzle, and suspended particulate matter (SPM) near the traffic route. Soxhlet extraction was performed on each sample. By gas-chromatograph-mass spectrometer (GC-MS) analysis of these extracts, di-ethyl phthalate and di- n-butyl phthalate were detected from the extract of SPM and diesel exhaust particles (DEPs). Because these phthalates were sometimes suspected as contamination, time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurements were also performed on the samples collected at the same environment. By comparing obtained spectra, it is clear that these environmental endocrine disrupters (EEDs) were adsorbed on DEP surface. Thus, we concluded that the combination of conventional method and TOF-SIMS measurement is one of the most powerful techniques for analyzing the toxic air pollutants adsorbed on SPM surface.

  17. Phthalates in PM2.5 airborne particles in the Moravian-Silesian Region, Czech Republic

    Directory of Open Access Journals (Sweden)

    Jana Růžičková

    2016-03-01

    Full Text Available Industrial area of the Moravian-Silesian Region (the Czech Republic is highly polluted by air contaminants, especially emissions of particulate matter. Samples of PM2.5 particles were analysed by pyrolysis gas chromatography with mass spectrometric detection. Concentrations of phthalates were determined for the winter season, transitional period and the summer season. The relative concentrations of phthalates in PM2.5 particles have the same proportion in both heating and non-heating season: di(2ethylexyl phthalate > di-n-butyl phthalate > diisononyl phthalate > diethyl phthalate. The most common increase in concentration in the winter season is from 5 to 10 times higher; the maximum of average concentration was 44 times higher than in the non-heating season.

  18. Personal exposure to airborne ultrafine particles in the urban area of Milan

    International Nuclear Information System (INIS)

    The relevance of health effects related to ultrafine particles (UFPs; aerodynamic diameter 5 particles/cm3. UFPs measures were divided on the basis of crossed environments or micro-environments, days of the week and day time (hours). The highest measured mean concentrations and data variability were observed during walking time and moving on motorized vehicles (bus and car), indicating that the highest exposure to UFPs can be reached near motorized traffic. The lowest exposures were observed in green areas and in office microenvironments. An appreciable difference between working and non-working days was observed. Concentration patterns and variation by days of the week and time periods appears related to time trends in traffic intensity.

  19. Airborne measurements of trace gas and aerosol particle emissions from biomass burning in Amazonia

    OpenAIRE

    Guyon, P; Frank, G. P.; M. Welling; D. Chand; Artaxo, P.; L. Rizzo; Nishioka, G.; Kolle, O.; Fritsch, H.; Silva Dias, M. A. F.; L. V. Gatti; Cordova, A. M.; Andreae, M.O.

    2005-01-01

    As part of the LBA-SMOCC (Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke, Aerosols, Clouds, Rainfall, and Climate) 2002 campaign, we studied the emission of carbon monoxide (CO), carbon dioxide (CO2), and aerosol particles from Amazonian deforestation fires using an instrumented aircraft. Emission ratios for aerosol number (CN) relative to CO (ERCN/CO) fell in the range 14–32 cm-3&nbs...

  20. Determination of the particle size distribution of aerosols by means of a diffusion battery

    International Nuclear Information System (INIS)

    The different methods allowing to determine the particle size distribution of aerosols by means of diffusion batteries are described. To that purpose, a new method for the processing of experimental data (percentages of particles trapped by the battery vs flow rate) was developed on the basis of calculation principles which are described and assessed. This method was first tested by numerical simulation from a priori particle size distributions and then verified experimentally using a fine uranine aerosol whose particle size distribution as determined by our method was compared with the distribution previously obtained by electron microscopy. The method can be applied to the determination of particle size distribution spectra of fine aerosols produced by 'radiolysis' of atmospheric gaseous impurities. Two other applications concern the detection threshold of the condensation nuclei counter and the 'critical' radii of 'radiolysis' particles

  1. Particle size effect for cobalt Fischer-Tropsch catalysts based on in situ CO chemisorption

    Science.gov (United States)

    Yang, Jia; Frøseth, Vidar; Chen, De; Holmen, Anders

    2016-06-01

    The cobalt particle size effect on activity and selectivity for CO hydrogenation was revisited on cobalt catalysts supported on a large variety of supports at 483 K, 1.85 bar, and H2/CO/Ar = 15/1.5/33.5 Nml/min. The size dependence of the activity and selectivity was analyzed in terms of site coverage and rate constants based on SSITKA experimental results. It was found that the Co particle size index estimated by the conventional method, namely, ex situ hydrogen chemisorption, could not correlate well the activity and selectivity as a function of the particle size index. The same holds for the site coverage of CO and intermediates leading to methane formation. However, the cobalt particle size index based on in situ CO chemisorption measured at 373 K provides a good correlation for turnover frequencies (TOFs) at reaction conditions. It was observed that TOF for CO conversion (TOFCO) increased with increasing particle size index of cobalt and SSITKA experiments showed that this was possibly due to increased site coverage of CO. The TOF for methane formation (TOFCH4) increased with particle size and remained constant at higher particle sizes possibly due to combined effect from the site coverage of intermediates leading to methane (θCHx) and the pseudo-first-order rate constant (kt). The results suggest that the support can play an important role for the size dependence of the activity and selectivity of CO hydrogenation on Co catalysts.

  2. Particle-size distribution and packing fraction of geometric random packings

    NARCIS (Netherlands)

    Brouwers, H.J.H.

    2006-01-01

    This paper addresses the geometric random packing and void fraction of polydisperse particles. It is demonstrated that the bimodal packing can be transformed into a continuous particle-size distribution of the power law type. It follows that a maximum packing fraction of particles is obtained when t

  3. Determination of Particle Size by Diffraction of Light

    Science.gov (United States)

    Rinard, Phillip M.

    1974-01-01

    Describes a simplified diffraction experiment offered in a workshop with the purpose of illustrating to high school students the relation of science to society. The radii determined for cigarette smoke particles range from 0.2 to 0.5 micrometer in this experiment. Included is a description of the diffraction theory. (CC)

  4. Particle size effects on bioaccessible amounts of ingestible soil-borne toxic elements.

    Science.gov (United States)

    Qin, Junhao; Nworie, Obinna Elijah; Lin, Chuxia

    2016-09-01

    The unified BARGE method was used to examine the effects of soil particle size on the bioaccessible amounts of potentially toxic elements in multi-contaminated soils from a closed landfill site. The results show that bioaccessible As, Al, Cd, Cr, Cu, Mn, Ni, Pb and Zn increased with decreasing soil particle size and the particle size effect on bioaccessibility of As and Al in the gastrointestinal phase: As bioaccessibility decreased with decreasing particle size, and the finer soil fractions tended to have a higher Al bioaccessibility, as compared to the coarser soil fractions. The research findings prompt the need for further division of soil particle size fractions in order to more accurately assess the bioaccessible amounts of soil-borne potentially toxic elements in contaminated lands. PMID:27337436

  5. Size control of rhodium particles of silica-supported catalysts using water-in-oil microemulsion

    Science.gov (United States)

    Kishida, Masahiro; Hanaoka, Toshiaki; Kim, Won Young; Nagata, Hideo; Wakabayashi, Katsuhiko

    1997-11-01

    Effects of components of water-in-oil microemulsions on rhodium particle sizes of silica-supported rhodium catalysts were investigated in the catalyst preparation method using microemulsion. In the case of the microemulsion of polyoxyethylene(23)dodecyl ether/ n-alcohols/RhCl 3 aq., the rhodium particle size increased from 3.4 to 5.0 nm as the specific permittivity of the organic solvent increased. The chain length of hydrophilic group of polyoxyethylene- p-nonylphenyl ether ( n = 5 to 15) employed as surfactants had an effect on the rhodium particle size where the rhodium size ranged between 2.0 and 3.6 nm. The rhodium particle size was 1.5 nm in the case of sodium bis(2-ethylhexyl) sulfocuccinate and this value was found to be the smallest. These results could be interpreted in terms of the adsorption of the surfactant on rhodium-hydrazine particle surface.

  6. Characteristics of flow in wet conical spouted beds of unequal-sized spherical Particles

    OpenAIRE

    M. S. Bacelos; PASSOS M. L.; J. T. Freire

    2008-01-01

    Interparticle forces, developed in wet spouted beds composed of a mixture of spherical particles with different size distributions, intensify particle segregation mechanisms interfering in gas distribution inside the bed and, consequently, in the spouting flow characteristics. Therefore, this paper is aimed at describing the effect of interparticle forces on the air-solid flow distribution in conical spouted beds of unequal-sized particles coated by a thin glycerol film. Experimental results ...

  7. Limitations on the use of laser velocimeter signals for particle sizing

    Science.gov (United States)

    Orloff, K. L.; Myer, F. C.; Mikasa, M. F.; Phillips, J. R.

    1976-01-01

    The paper discusses the complex relationship existing between the diameter of a particle, its index of refraction, and the output signal of a fringe-type laser velocimeter, and describes a special purpose laser velocimeter for aerosol sizing that determines aerosol size distributions on the basis of Farmer's (1973) relationship between visibility and particle size. In experiments with particles of known size, this relationship is in qualitative agreement with the experimentally observed results, the main differences being that (1) the visibility does not assume a minimum value of zero, as predicted, and (2) the visibility value above which there is no ambiguity in the corresponding fringe spacing is higher than that predicted.

  8. Coalbed methane adsorption and desorption characteristics related to coal particle size

    Science.gov (United States)

    Yan-Yan, Feng; Wen, Yang; Wei, Chu

    2016-06-01

    Effects of particle size on CH4 and CO2 adsorption and desorption characteristics of coals are investigated at 308 K and pressures up to 5.0 MPa. The gas adsorption and desorption isotherms of coals with particle sizes ranging from 250 μm to 840 μm are measured via the volumetric method, and the Langmuir model is used to analyse the experimental results. Coal particle size is found to have an obvious effect on the coal pore structure. With the decrease of coal particle size in the process of grinding, the pore accessibility of the coal, including the specific surface area and pore volume, increases. Hence, coal with smaller particle size has higher specific surface area and higher pore volume. The ability of adsorption was highly related to the pore structure of coal, and coal particle size has a significant influence on coal adsorption/desorption characteristics, including adsorption capacity and desorption hysteresis for CH4 and CO2, i.e., coal with a smaller particle size achieves higher adsorption capacity, while the sample with a larger particle size has lower adsorption capacity. Further, coal with larger particle size is also found to have relatively large desorption hysteresis. In addition, dynamic adsorption performances of the samples are carried out at 298 K and at pressures of 0.1 MPa and 0.5 MPa, respectively, and the results indicate that with the increase of particle size, the difference between CO2 and CH4 adsorption capacities of the samples decreases. Project supported by the National Basic Research Program of China (Grant No. 2011CB201202).

  9. Design of a Particle Shadow-graph Velocimetry and Size (PSVS) System to Determine Particle Size and Density Distributions in Hanford Nuclear Tank Wastes - 12280

    International Nuclear Information System (INIS)

    Accurate particle size and density distributions for nuclear tank waste materials are essential information that helps determine the engineering requirements for a host of waste management unit operations (e.g., tank mixing, pipeline transport, and filtration). The most prevalent approach for determining particle size and density distribution is highly laborious and involves identifying individual particles using scanning electron microscope/x-ray diffraction and then acquiring the density of the materials from the technical literature. Other methods simply approximate individual particle densities by assuming chemical composition, rather than obtaining actual measurements of particle density. To overcome these limitations, a Particle Shadow-graph Velocimetry and Size (PSVS) system has been designed to simultaneously obtain particle size and density distributions for a broad range of Hanford tank waste materials existing as both individual particles and agglomerates. The PSVS system uses optical hardware, a temperature-controlled settling column, and particle introduction chamber to accurately and reproducibly obtain images of settling particles. Image analysis software provides a highly accurate determination of both particle terminal velocity and equivalent spherical particle diameter. The particle density is then calculated from Newton's terminal settling theory. The PSVS system was designed to accurately image particle/agglomerate sizes between 10 and 1000 μm and particle/agglomerate densities ranging from 1.4 to 11.5 g/cm3, where the maximum terminal velocity does not exceed 10 cm/s. Preliminary testing was completed with standard materials and results were in good agreement with terminal settling theory. Recent results of this method development are presented, as well as experimental design. The primary goal of these PSVS system tests was to obtain accurate and reproducible particle size and velocity measurements to estimate particle densities within 20

  10. Study on effective particle diameters and coolability of particulate beds packed with irregular multi-size particles

    International Nuclear Information System (INIS)

    One of the key questions in severe accident research is the coolability of the debris bed, i.e., whether decay heat can be completely removed by the coolant flow into the debris bed. Extensive experimental and analytical work has been done to substantiate the coolability research. Most of the available experimental data is related to the beds packed with single size (mostly spherical) particles, and less data is available for multi-size/irregular-shape particles. There are several analytical models available, which rely on the mean particle diameter and porosity of the bed in their predictions. Two different types of particles were used to investigate coolability of particulate beds at VTT, Finland. The first type is irregular-shape Aluminum Oxide gravel particles whose sizes vary from 0.25 mm to 10 mm, which were employed in the STYX experiment programme (2001-2008). The second type is spherical beads of Zirconium silicate whose sizes vary between 0.8 mm to 1 mm, which were used in the COOLOCE tests (Takasuo et al., 2012) to study the effect of multi-dimensional flooding on coolability. In the present work, the two types of particles are used in the POMECO-FL and POMECO-HT test facility to obtain their effective particle diameters and dryout heat flux of the beds, respectively. The main idea is to check how the heaters' orientations (vertical in COOLOCE vs. horizontal in POMECO-HT) and diameters (6 mm in COOLOCE vs. 3 mm in POMECO-HT) affect the coolability (dryout heat flux) of the test beds. The tests carried out on the POMECO-FL facility using a bed packed with aluminum oxide gravel particles show the effective particle diameter of the gravel particles is 0.65 mm, by which the frictional pressure gradient can be predicted by the Ergun equation. After the water superficial velocity is higher than 0.0025 m/s, the pressure gradient is underestimated. The effective particle diameter of the zirconium particles is found as 0.8 mm. The dryout heat flux is measured on

  11. Biofilm effects on size gradation, drag coefficient and settling velocity of sediment particles

    Institute of Scientific and Technical Information of China (English)

    Qian-qian SHANG; Hong-wei FANG; Hui-ming ZHAO; Guo-jian HE; Zheng-hui CUI

    2014-01-01

    Sediment particles are often colonized by biofilm in a natural aquatic ecological system, especially in eutrophic water body. A series of laboratory experiments on particle size gradation, drag coefficient and settling velocity were conducted after natural sediment was colonized by biofilm for 5, 10, 15 and 20 days. Particle image acquisition, particle tracking techniques of Particle Image Velocimetry and Particle Tracking Velocimetry were utilized to analyze the changes of these properties. The experimental results indicate that the size gradation, the drag force exerted on bio-particles, and the settling velocity of bio-particles underwent significant change due to the growth of biofilm onto the sediment surface. The study proposes a characteristic particle size formula and a bio-particle settling velocity formula based on the regression of experiment results, that the settling velocity is only 50% to 60%as the single particle which has the same diameter and density. However, biofilm growth causes large particle which the settling velocities are approximately 10 times larger than that of primary particles. These results may be specifically used in the low energy reservoir or lake environment.

  12. Ion acoustic and dust acoustic waves at finite size of plasma particles

    International Nuclear Information System (INIS)

    We consider the influence of the finite size of ions on the properties of classic plasmas. We focus our attention at the ion acoustic waves for electron-ion plasmas. We also consider the dusty plasmas where we account the finite size of ions and particles of dust and consider the dispersion of dust acoustic waves. The finite size of particles is a classical effect as well as the Coulomb interaction. The finite size of particles considerably contributes to the properties of the dense plasmas in the small wavelength limit. Low temperature dense plasmas, revealing the quantum effects, are also affected by the finite size of plasma particles. Consequently, it is important to consider the finite size of ions in the quantum plasmas as well

  13. Synthesis and optical properties of quantum-size metal sulfide particles in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Nedeljkovic, J.M.; Patel, R.C.; Kaufman, P.; Joyce-Pruden, C.; O' Leary, N. (Clarkson Univ., Potsdam, NY (United States))

    1993-04-01

    During the past decade, small-particle' research has become quite popular in various fields of chemistry and physics. The recognition of quantum-size effects in very small colloidal particles has led to renewed interest in this area. Small particles' are clusters of atoms or molecules ranging in size from 1 nm to almost 10 nm or having agglomeration numbers from 10 up to a few hundred. In other words, small particles fall in size between single atoms or molecules and bulk materials. The agglomeration number specifies the number of individual atoms or molecules in a given cluster. The research in this area is interdisciplinary, and it links colloidal science and molecular chemistry. The symbiosis of these two areas of research has revealed some intriguing characteristics of small particles. This experiment illustrates the following: simple colloidal techniques for the preparation of two different types of quantum-size metal sulfide particles; the blue shift of the measured optical absorption spectra when the particle size is decreased in the quantum-size regime; and use of a simple quantum mechanical model to calculate the particle size from the absorption onset measured for CdS.

  14. Alpha spectrometry for particle size determination of mineral sands dust samples

    International Nuclear Information System (INIS)

    A method is proposed for assessing the size distribution of the radioactive particles directly from the alpha spectrum of a dust sample. The residual range distribution of alpha particles emerging from a sphere containing a monoenergetic alpha emitter is simply a quadratic function of the diameter of the sphere. The residual range distribution from a typical dust particle closely approximates that of a sphere of the same mass. For mixtures of various size particles of similar density the (multiparticle) residual range distribution can thus readily be calculated for each of the alpha emitters contained in the particles. Measurement of the composite residual range distribution can be made in a vacuum alpha spectrometer provided the dust sample has no more than a monolayer of particles. The measured energy distribution is particularly sensitive to upper particle size distributions in the diameter region of 4μm to 20μm of 5 mg/cm3 density particles, i.e. 2 to 10 mg/ch2. For dust particles containing212Po or known ratios of alpha emitters a measured alpha spectrum can be unraveled to the underlying particle size distribution. Uncertainty in the size distribution has been listed as deserving research priority in the overall radiation protection program of the mineral sands industry. The proposed method had the potential of reducing this uncertainty, thus permitting more effective radiation protection control. 2 refs., 1 tabs., 1 figs

  15. Experimental study on size-dependency of effective permittivity of particle-gas mixture with agglomeration

    Institute of Scientific and Technical Information of China (English)

    Li Xiaomin; Xu Lijun; Li Songyun

    2007-01-01

    The effective medium approximation (EMA) theory is the basis of a capacitance sensor used for concentration measurement of a particulate solid flow, its measurement result is independent on particle size. In existence of particle agglomeration or aggradation, however, it is found that the effective permittivity of a gas/solid mixture is dependent on particle size. In this paper, a parallel plate, differential capacitance sensor is utilized to investigate the influence of particle size on the effective permittivity of the mixture in such a case. Static experiments using three materials including glass, limestone and quartz particles were carried out in an off-line manner. The volume fraction of particles being tested ranged from 20×10-6 to 600×10-6, while the particle size was between 3 and 100 μm. Experimental results show that the effective permittivity of a particle-gas mixture with particle agglomeration is larger than that predicted by EMA and the smaller the particle size, the larger the effective permittivity. The experiment process and analysis results are discussed in detail in the paper.

  16. Selection of filter media used for monitoring airborne alpha-emitting particles in a radiological emergency

    International Nuclear Information System (INIS)

    We have developed on air monitor for alpha-emitting particles released to the atmosphere at an accident of nuclear reprocessing plant. Selection of a suitable filter for the monitor is considerably important in order to achieve the high-sensitive measurement of radioactive concentration. We have examined surface collection efficiencies and pressure drops for the various filters that are commercially available in Japan. It was found that the PTFE membrane filter with backing had superior performance to the others, that is, a high surface collection efficiency and low pressure drop. (author)

  17. Investigation of Composition of Particle Size in Sediments of Stormwater Sedimentation Tank

    Directory of Open Access Journals (Sweden)

    Daiva Laučytė

    2011-04-01

    Full Text Available The main object for the storm water runoff treatment is to remove suspended solids before the storm water runoff is discharged into surface waters. Therefore the sedimentation tank is the most often used treatment facility. In order to optimise the sedimentation, the tendency of particle size distribution in bottom sediments must be known. Two similar size storm water runoff sedimentation tanks in Vilnius city were selected for the analysis of the particle size distribution in sediments. The composite samples of drained storm water runoff sediments were collected at the sedimentation tanks located in the districts of Verkiai and Karoliniskes on the 2nd of June, 2008. The analyses of grain size distribution were performed according the standard ISO/TS 17892-4:2004. The results showed that the particles with the particle size of 1–2 mm were obtained up to 10 m from the inlet and the particles with the size of 0,01–0,05 mm mainly were obtained close to the outlet of sedimentation tank. It is recommended to divide the sedimentation tank in two parts in order to get proper management of sediments: the particles that size is 1–10 mm could be managed as waste from grit chambers and particles of smaller size could be managed as primary sludge.Article in Lithuanian

  18. Effect of sodium citrate on preparation of nano-sized cobalt particles by organic colloidal process

    Institute of Scientific and Technical Information of China (English)

    Huaping ZHU; Hao LI; Huiyu SONG; Shijun LIAO

    2009-01-01

    Nano-sized cobalt particles with the diameter of 2 nm were prepared via an organic colloidal process with sodium formate, ethylene glycol and sodium citrate as the reducing agent, the solvent and the complexing agent, respectively. The effects of sodium citrate on the yield, crystal structure, particle size and size distribution of the prepared nano-sized cobalt particles were then investigated. The results show that the average particle diameter decreases from 200 nm to 2 nm when the molar ratio of sodium citrate to cobalt chloride changes from 0 to 6. Furthermore, sodium citrate plays a crucial role in the controlling of size distribution of the nano-sized particles. The size distribution of the particle without sodium citrate addition is in range from tens of nanometers to 300 or 400 nm, while that with sodium citrate addition is limited in the range of (2±0.25) nm. Moreover, it is found that the addition of sodium citrate as a complex agent could decrease the yield of the nano-sized cobalt particle.

  19. The Influence of the Particle Size on the Adhesion Between Ceramic Particles and Metal Matrix in MMC Composites

    Science.gov (United States)

    Jarzabek, Dariusz M.; Chmielewski, Marcin; Dulnik, Judyta; Strojny-Nedza, Agata

    2016-05-01

    This study investigated the influence of the particle size on the adhesion force between ceramic particles and metal matrix in ceramic-reinforced metal matrix composites. The Cu-Al2O3 composites with 5 vol.% of ceramic phase were prepared by a powder metallurgy process. Alumina oxide powder as an electrocorundum (Al2O3) powder with different particle sizes, i.e., fine powder materials and carried out the experiments with the use of the self-made tensile tester. We have observed that the interface strength is higher for the sample with coarse particles and is equal to 74 ± 4 MPa and it is equal to 68 ± 3 MPa for the sample with fine ceramic particles.

  20. Lifetimes and Sizes from Two-Particle Correlation Functions

    OpenAIRE

    Heinz, U.; Tomasik, B.; Wiedemann, U. A.; Wu, Y. -F.

    1996-01-01

    We discuss the Yano-Koonin-Podgoretskii (YKP) parametrization of the two-particle correlation function for azimuthally symmetric expanding sources. We derive model-independent expressions for the YKP fit parameters and discuss their physical interpretation. We use them to evaluate the YKP fit parameters and their momentum dependence for a simple model for the emission function and propose new strategies for extracting the source lifetime. Longitudinal expansion of the source can be seen direc...

  1. Estimation of size distribution of primary particles after evaporation or urane(IV) oxide

    International Nuclear Information System (INIS)

    Studying the behaviour of urane oxide aerossoles in a closed system the size distribution of the particles resulting from evaporation of UO2 was also investigated. They were precipitated on formfar coated specimen supports grids and photographed with an electron microscope. For the estimation of the size distribution the projected diameter was used. The results show that the size distribution of the primary particles corresponds to a logarithmic normal distribution. (author)

  2. Laboratory and field evaluations of the LISST-100 instrument for suspended particle size determinations

    Science.gov (United States)

    Gartner, J.W.; Cheng, R.T.; Wang, P.-F.; Richter, K.

    2001-01-01

    Advances in technology have resulted in a new instrument that is designed for in-situ determination of particle size spectra. Such an instrument that can measure undisturbed particle size distributions is much needed for sediment transport studies. The LISST-100 (Laser In-Situ Scattering and Transmissometry) uses the principle of laser diffraction to obtain the size distribution and volume concentration of suspended material in 32 size classes logarithmically spaced between 1.25 and 250 ??m. This paper describes a laboratory evaluation of the ability of LISST-100 to determine particle sizes using suspensions of single size, artificial particles. Findings show the instrument is able to determine particle size to within about 10% with increasing error as particle size increases. The instrument determines volume (or mass) concentration using a volume conversion factor Cv. This volume conversion factor is theoretically a constant. In the laboratory evaluation Cv is found to vary by a factor of about three over the particle size range between 5 and 200 ??m. Results from field studies in South San Francisco Bay show that values of mass concentration of suspended marine sediments estimated by LISST-100 agree favorably with estimates from optical backscatterance sensors if an appropriate value of Cv, according to mean size, is used and the assumed average particle (aggregate) density is carefully chosen. Analyses of size distribution of suspended materials in South San Francisco Bay over multiple tide cycles suggest the likelihood of different sources of sediment because of different size characteristics during flood and ebb cycles. ?? 2001 Elsevier Science B.V.

  3. Airborne Particles in the Baroque Hall of the National Library in Prague

    Czech Academy of Sciences Publication Activity Database

    Mašková, Ludmila; Džumbová, Lucie; Ondráček, Jakub; Smolík, Jiří; Grontoft, T.; López-Aparicio, S.; Stankiewicz, J.

    - : -, 2010, s. 133. ISBN N. [ Indoor Air Quality Meeting /9./. Chalon-sur-Saone (FR), 21.04.2010-23.04.2010] R&D Projects: GA MŠk OC09049 Grant ostatní: MF(CZ) CZ0046/2/0001 Institutional research plan: CEZ:AV0Z40720504 Keywords : indoor /outdoor aerosol * number size distribution Subject RIV: CF - Physical ; Theoretical Chemistry

  4. Characterization of Airborne Particles in the Baroque Hall of the National Library in Prague

    Czech Academy of Sciences Publication Activity Database

    Mašková, Ludmila; Smolík, Jiří; Džumbová, Lucie; Ondráček, Jakub; López-Aparicio, S.; Grontoft, T.; Stankiewicz, J.

    -, č. 7 (2010), s. 141-146. ISSN 1581-9280. [9th Indoor Air Quality Meeting. Chalon-sur-Saone, 21.04.2010-23.04.2010] R&D Projects: GA MŠk OC09049 Grant ostatní: MF NF(CZ) A/CZ0046/2/0001 Institutional research plan: CEZ:AV0Z40720504 Keywords : indoor /outdoor aerosol * mass size distribution * chemical composition Subject RIV: CF - Physical ; Theoretical Chemistry

  5. Characterization of Airborne Particles in the Baroque Hall of the National Library in Prague

    Czech Academy of Sciences Publication Activity Database

    Džumbová, Lucie; Mašková, Ludmila; Ondráček, Jakub; Smolík, Jiří; Grontoft, T.; López-Aparicio, S.; Stankiewicz, J.

    - : -, 2010, s. 55. ISBN N. [ Indoor Air Quality Meeting /9./. Chalon-sur-Saone (FR), 21.04.2010-23.04.2010] R&D Projects: GA MŠk OC09049 Grant ostatní: MF(CZ) CZ0046/2/0001 Institutional research plan: CEZ:AV0Z40720504 Keywords : indoor /outdoor aerosol * mass size distribution * chemical composition Subject RIV: CF - Physical ; Theoretical Chemistry

  6. Particle size-dependent leakage and losses of aerosols in respirators

    Energy Technology Data Exchange (ETDEWEB)

    Holton, P.M.; Tackett, D.L.; Willeke, K.

    1987-10-01

    Measuring particle size-dependent leakage into and losses inside a respirator reveals the deposition mechanisms occurring at the leak site and the flow dynamics inside the respirator. This study investigated particle size-dependent leakage and deposition within the mask by examining the leakage into the mask for different hole locations, probe locations, hole shapes, hole lengths and hole sizes. The shape of the leak has an effect on particle size-dependent leakage. Probe and leak location tests indicated that not only does the total measured leakage change but also the size-dependence of the leakage changes depending on the leak and probe locations. When the leak site is in the chin area, the clean air entering through the filters at the chin helps to carry the inward leakage into the breathing zone. Particle size-dependent leakage does occur and is due to both inertial entry losses at the leak site and within the mask, and diffusional losses within the mask and leak site. Particle size-dependent curves change shape as the hole size changes with relatively more larger particles entering through the small hole size.

  7. Size Distribution of Particles Emitted from Liquefied Natural Gas Fueled Engine

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The results of measurements conducted to determine the number and mass concentration of particles emitted from the liquefied natural gas (LNG) fueled spark ignition engines are presented. Particle size distributions were measured at different speeds, different loads and ESC cycles. The nanoparticles with diameter smaller than 39nm, measured by the electrical low-pressure impactor (ELPI), are dominant in number concentration that is nearly 92.7% of the total number of the emitted particles at the peak point. As for the mass of emission particle, it is shown that the mass of the particles greater than 1.2μm is more than 65% that of the emitted particles.

  8. A Review of Discrete Element Method (DEM) Particle Shapes and Size Distributions for Lunar Soil

    Science.gov (United States)

    Lane, John E.; Metzger, Philip T.; Wilkinson, R. Allen

    2010-01-01

    As part of ongoing efforts to develop models of lunar soil mechanics, this report reviews two topics that are important to discrete element method (DEM) modeling the behavior of soils (such as lunar soils): (1) methods of modeling particle shapes and (2) analytical representations of particle size distribution. The choice of particle shape complexity is driven primarily by opposing tradeoffs with total number of particles, computer memory, and total simulation computer processing time. The choice is also dependent on available DEM software capabilities. For example, PFC2D/PFC3D and EDEM support clustering of spheres; MIMES incorporates superquadric particle shapes; and BLOKS3D provides polyhedra shapes. Most commercial and custom DEM software supports some type of complex particle shape beyond the standard sphere. Convex polyhedra, clusters of spheres and single parametric particle shapes such as the ellipsoid, polyellipsoid, and superquadric, are all motivated by the desire to introduce asymmetry into the particle shape, as well as edges and corners, in order to better simulate actual granular particle shapes and behavior. An empirical particle size distribution (PSD) formula is shown to fit desert sand data from Bagnold. Particle size data of JSC-1a obtained from a fine particle analyzer at the NASA Kennedy Space Center is also fitted to a similar empirical PSD function.

  9. A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

    Science.gov (United States)

    Bastian, S.; Löschau, G.; Wiedensohler, A.

    2014-04-01

    An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The function control allows unattended quality assurance experiments at remote air quality monitoring or research stations under field conditions. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter while removing diffusive particles smaller than 20 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. Another feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. The performance of the function control is illustrated with the aid of a 1-year data set recorded at Annaberg-Buchholz, a station in the Saxon air quality monitoring network. During the period of concern, the total particle number concentration derived from the mobility particle size spectrometer slightly overestimated the particle number concentration recorded by the condensation particle counter by 2 % (grand average). Based on our first year of experience with the function control, we developed tolerance criteria that allow a performance evaluation of a tested mobility particle size spectrometer with respect to the total particle number concentration. We conclude that the automated function control enhances the quality and reliability of unattended long-term particle number size distribution measurements. This will have beneficial effects for intercomparison studies involving different measurement sites, and help provide a higher

  10. Theoretical Study on the Effects of Particle Size Distribution on the Optical Properties of Colloidal Gold

    International Nuclear Information System (INIS)

    Mie theory has been used to calculate the extinction of a gold nanoparticle in water by varying its diameter from 1 to 1000 nm. Utilizing this size-dependent theoretical spectrum, we have calculated the extinction spectrum of a colloidal gold by taking into account the size distribution of particle. Such calculation is in better agreement with experiment than the calculation without considering the size distribution. A least-squares fitting is used to deduce the size distribution from an experimental extinction spectrum. For particles with their diameters ranging from 10 to 28 nanometers, the fitting gives reasonable agreement with the size distribution obtained from tunneling electron microscope images

  11. Rural measurements of the chemical composition of airborne particles in the Eastern United States

    International Nuclear Information System (INIS)

    Quantitative measurements of particulate composition was made at three rural sites: in central South Dakota, on the Louisiana Gulf Coastal, and in the Blue Ridge Mountains of Virginia. The first two sites were selected to determine background concentrations in continental polar and maritime tropical air masses, respectively, which affect the eastern United State during the summer. The Virginia site was selected as a receptor site, downwind of the midwestern source area. The South Dakota data established the background concentrations. These concentrations were similar to the levels in Louisiana when air parcels arrived from the Gulf of Mexico, without recently passing over the United States. Levels of fine particles (diameters less than 2.5 μm) were highest in Virginia and were due chiefly to sulfate. Using trajectory and statistical analyses, it is shown that the residence time of an air parcel over the midwestern source area was the most important variable in determining the sulface levels in the Blue Ridge Mountains

  12. Particle Size Dependence of TiO2 Electrodes in Rechargeable Lithium Battery

    Directory of Open Access Journals (Sweden)

    S. Y. Huang

    1996-01-01

    Full Text Available Particle size effects in five anatase TiO2 pellet electrodes with different particle sizes (4 ∼ 300nm and surface areas (8 ∼ 380m2/g were studied by XRD analysis, chronopotentiometry and chronoamperometry in Li/LiN(CF3SO22 + EC:DME/TiO2 cells. Nanosized TiO2 electrodes showed by 22% larger storage capacity, 50% lower overvoltage loss at the same current density, and 75% higher charge density for a given time than microsized ones; electric storage capacity enhances more rapidly with decreasing particle size and increasing surface area in a nanoscale region than in a microscale region. The particle size dependence may be explained by surface morphology of electrodes and existence of structural defects or distortion in the surface layer of TiO2 nanosized particles.

  13. Radial particle-size segregation during packing of particulates into cylindrical containers

    Science.gov (United States)

    Ripple, C.D.; James, R.V.; Rubin, J.

    1973-01-01

    In a series of experiments, soil materials were placed in long cylindrical containers, using various packing procedures. Soil columns produced by deposition and simultaneous vibratory compaction were dense and axially uniform, but showed significant radial segregation of particle sizes. Similar results were obtained with deposition and simultaneous impact-type compaction when the impacts resulted in significant container "bouncing". The latter procedure, modified to minimize "bouncing" produced dense, uniform soil columns, showing little radial particle-size segregation. Other procedures tested (deposition alone and deposition followed by compaction) did not result in radial segregation, but produced columns showing either relatively low or axially nonuniform densities. Current data suggest that radial particle-size segregation is mainly due to vibration-induced particle circulation in which particles of various sizes have different circulation rates and paths. ?? 1973.

  14. Effects of particle size on residual stresses of metal matrix composites

    Institute of Scientific and Technical Information of China (English)

    YAN Yi-wu; GENG Lin; LI Ai-bin

    2006-01-01

    A finite element analysis was carried out on the development of residual stresses during the cooling process from the fabrication temperature in the SiCp reinforced Al matrix composites. In the simulation, the two-dimensional and random distribution multi-particle unit cell model and plane strain conditions were used. By incorporating the Taylor-based nonlocal plasticity theory, the effect of particle size on the nature, magnitude and distribution of residual stresses of the composites was studied. The magnitude thermal-stress-induced plastic deformation during cooling was also calculated. The results show similarities in the patterns of thermal residual stress and strain distributions for all ranges of particle size. However, they show differences in magnitude of thermal residual stress as a result of strain gradient effect. The average thermal residual stress increases with decreasing particle size, and the residual plastic strain decreases with decreasing particle size.

  15. Size Effects in Heterogeneous Systems with Nanoscale Particles

    Czech Academy of Sciences Publication Activity Database

    Levdansky, V.V.; Smolík, Jiří; Ždímal, Vladimír

    -: -, 2011, s. pc3 16. ISBN N. [E- MRS 2011 Spring Meeting IUMRS ICAM 2011 & E- MRS / MRS Bilateral Conference on Energy. Nice (FR), 09.05.2011-13.05.2011] R&D Projects: GA ČR GA101/09/1633; GA AV ČR(CZ) IAA400720804; GA AV ČR IAA200760905 Institutional research plan: CEZ:AV0Z40720504 Keywords : nanoscale particles * aeerosol systems * gas Subject RIV: CF - Physical ; Theoretical Chemistry http://www.emrs-strasbourg.com/index.php?option=com_abstract&task=view&id=118&day=2011-05-12&year=2011&Itemid=99999999&id_season=4.

  16. Effect of sulfate and carbonate minerals on particle-size distributions in arid soils

    Science.gov (United States)

    Goossens, Dirk; Buck, Brenda J.; Teng, Yuazxin; Robins, Colin; Goldstein, Harland L.

    2014-01-01

    Arid soils pose unique problems during measurement and interpretation of particle-size distributions (PSDs) because they often contain high concentrations of water-soluble salts. This study investigates the effects of sulfate and carbonate minerals on grain-size analysis by comparing analyses in water, in which the minerals dissolve, and isopropanol (IPA), in which they do not. The presence of gypsum, in particular, substantially affects particle-size analysis once the concentration of gypsum in the sample exceeds the mineral’s solubility threshold. For smaller concentrations particle-size results are unaffected. This is because at concentrations above the solubility threshold fine particles cement together or bind to coarser particles or aggregates already present in the sample, or soluble mineral coatings enlarge grains. Formation of discrete crystallites exacerbates the problem. When soluble minerals are dissolved the original, insoluble grains will become partly or entirely liberated. Thus, removing soluble minerals will result in an increase in measured fine particles. Distortion of particle-size analysis is larger for sulfate minerals than for carbonate minerals because of the much higher solubility in water of the former. When possible, arid soils should be analyzed using a liquid in which the mineral grains do not dissolve, such as IPA, because the results will more accurately reflect the PSD under most arid soil field conditions. This is especially important when interpreting soil and environmental processes affected by particle size.

  17. Particle-size distribution of polybrominated diphenyl ethers (PBDEs) and its implications for health

    Science.gov (United States)

    Lyu, Y.; Xu, T.; Li, X.; Cheng, T.; Yang, X.; Sun, X.; Chen, J.

    2015-12-01

    In order better to understand the particle-size distribution of particulate PBDEs and their deposition pattern in human respiratory tract, we made an one year campaign 2012-2013 for the measurement of size-resolved aerosol particles at Shanghai urban site. The results showed that particulate PBDEs exhibited a bimodal distribution with a mode peak in the accumulation particle size range and the second mode peak in the coarse particle size ranges. As the number of bromine atoms in the molecule increased, accumulation mode peak intensity increased while coarse mode peak intensity decreased. This change was the consistent with the variation of PBDEs' sub-cooled vapor pressure. Absorption and adsorption process dominated the distribution of PBDEs among the different size particles. Evaluated deposition flux of Σ13PBDE was 26.8 pg h-1, in which coarse particles contributed most PBDEs in head and tracheobronchial regions, while fine mode particles contributed major PBDEs in the alveoli region. In associated with the fact that fine particles can penetrate deeper into the respiratory system, fine particle-bound highly brominated PBDEs can be inhaled more deeply into human lungs and cause a greater risk to human health.

  18. Size distribution of particle-associated polybrominated diphenyl ethers (PBDEs) and their implications for health

    Science.gov (United States)

    Lyu, Yan; Xu, Tingting; Li, Xiang; Cheng, Tiantao; Yang, Xin; Sun, Xiaomin; Chen, Jianmin

    2016-03-01

    In order to better understand the size distribution of particle-associated PBDEs and their deposition pattern in the human respiratory tract, we carried out a 1-year campaign during 2012-2013 for the measurement of size-resolved particles at the urban site of Shanghai. The results showed that particulate PBDEs exhibited a bimodal distribution with a mode peak in the accumulation particle size range and the second mode peak in the coarse particle size ranges. As the number of bromine atoms in the molecule increases, accumulation-mode peak intensity increased while coarse-mode peak intensity decreased. This change was consistent with the variation of PBDEs' subcooled vapor pressure. Absorption and adsorption processes dominated the distribution of PBDEs among the different size particles. The evaluated deposition flux of Σ13 PBDEs was 26.8 pg h-1, in which coarse particles contributed most PBDEs in head and tracheobronchial regions, while fine-mode particles contributed major PBDEs in the alveoli region. In association with the fact that fine particles can penetrate deeper into the respiratory system, fine-particle-bound highly brominated PBDEs can be inhaled more deeply into human lungs and cause a greater risk to human health.

  19. Particle size and support effects in NO adsorption on model Pt and Rh catalysts

    International Nuclear Information System (INIS)

    The adsorption of NO on Rh particles supported on ZrO2 (100) and α-Al2O3(0001) and on Pt particles supported on CeO2, α-Al2O3(0001), and the Zn- and O-polar surfaces of ZnO(0001) has been studied using temperature programmed desorption (TPD). For Rh, the support affected the stability of the metal films and the final particle size but made no observable changes in NO adsorption properties. However, the TPD curves were found to be strongly dependent on the particle size for Rh. A low-temperature N2 feature which is observed on bulk metals and large particles was not seen with small Rh particles. For Pt, both support composition and particle size influenced the TPD results. The results for CeO2 and α-Al2O3(0001) were essentially identical, and the changes in the NO TPD curves appear to be due to particle size only. The implications of these results on particle size and support effects in NO reduction catalysis will be discussed

  20. Particle size of unattached radon progeny in filtered room air

    International Nuclear Information System (INIS)

    The size distribution of the unattached radon progeny in filtered room air was measured with a serial array of wire screens. Nearly all the size distributions of 2 to 3 min air, measured with the graded wire screen samplers were unimodal, with a geometric standard deviation averaging 1.8 ± 0.058. The grand average of the geometric mean and standard error of the mean diffusion coefficient was 0.048 ± 0.0004. The results obtained using different combinations of the graded wire screens were consistent. The measured diffusion coefficient predicts a nasal penetration of 9% to 16% for inspiratory flow rates of 3 1.min-1 to 30 min-1, respectively. The results indicate that about 15% of the inhaled unattached radon progeny penetrate beyond the nose into the tracheobronchial region to deliver a radiation dose to the bronchial epithelium. (author)

  1. A novel method for size uniform 200nm particles: multimetallic particles and in vitro gene delivery

    Science.gov (United States)

    Mair, Lamar; Ford, Kris; Superfine, Richard

    2008-10-01

    We report on the fabrication of arrays of mono- and multimetallic particles via metal evaporation onto lithographically patterned posts. Metal particles evaporated on cylindrical structures 0.20μm in diameter and 0.33μm tall are released via photoresist dissolution, resulting in freely suspended, shape defined particles. These Post-Particles have highly tunable composition, as demonstrated by our deposition of five different multimetallic particle blends. We calculate the susceptibility and magnetization of 200nm Fe particles in an applied 0.081T magnetic field. In order to evaluate their usefulness as magnetofection agents an antisense oligonucleotide designed to correct the aberrant splicing of enhanced green fluorescent protein mRNA was successfully attached to Fe Post-Particles via a polyethyleneimine linker and transfected into a modified HeLa cell line.

  2. Size Dependence of Chemical Reactions in Nanoscale Aerosol Particles

    Czech Academy of Sciences Publication Activity Database

    Levdansky, V.V.; Smolík, Jiří; Moravec, Pavel

    Helsinki : -, 2010, P2L1. ISBN N. [International Aerosol Conference IAC 2010. Helsinki (FI), 29.08.2010-03.09.2010] R&D Projects: GA ČR GA104/07/1093; GA ČR GA101/09/1633; GA AV ČR(CZ) IAA400720804 Institutional research plan: CEZ:AV0Z40720504 Keywords : size effect * nanoparticles * chemical reactions Subject RIV: CF - Physical ; Theoretical Chemistry www.iac2010.fi

  3. Deformation Behavior of Sub-micron and Micron Sized Alumina Particles in Compression.

    Energy Technology Data Exchange (ETDEWEB)

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay; Mook, William; Boyce, Brad; Kotula, Paul Gabriel; McKenzie, Bonnie Beth; Bufford, Daniel Charles; Hall, Aaron Christopher.

    2014-09-01

    The ability to integrate ceramics with other materials has been limited due to high temperature (>800degC) ceramic processing. Recently, researchers demonstrated a novel process , aerosol deposition (AD), to fabricate ceramic films at room temperature (RT). In this process, sub - micro n sized ceramic particles are accelerated by pressurized gas, impacted on the substrate, plastically deformed, and form a dense film under vacuum. This AD process eliminates high temperature processing thereby enabling new coatings and device integration, in which ceramics can be deposited on metals, plastics, and glass. However, k nowledge in fundamental mechanisms for ceramic particle s to deform and form a dense ceramic film is still needed and is essential in advancing this novel RT technology. In this wo rk, a combination of experimentation and atomistic simulation was used to determine the deformation behavior of sub - micron sized ceramic particle s ; this is the first fundamental step needed to explain coating formation in the AD process . High purity, singl e crystal, alpha alumina particles with nominal size s of 0.3 um and 3.0 um were examined. Particle characterization, using transmission electron microscopy (TEM ), showed that the 0.3 u m particles were relatively defect - free single crystals whereas 3.0 u m p articles were highly defective single crystals or particles contained low angle grain boundaries. Sub - micron sized Al 2 O 3 particles exhibited ductile failure in compression. In situ compression experiments showed 0.3um particles deformed plastically, fractured, and became polycrystalline. Moreover, dislocation activit y was observed within the se particles during compression . These sub - micron sized Al 2 O 3 particles exhibited large accum ulated strain (2 - 3 times those of micron - sized particles) before first fracture. I n agreement with the findings from experimentation , a tomistic simulation s of nano - Al 2 O 3 particles showed dislocation slip and

  4. Particle size dependence of hit probability for lung cells

    International Nuclear Information System (INIS)

    The macroscopic quantity 'absorbed dose' loses its validity to interpret the radiation-induced biological effects in the lung inhaled with particulate α-emitters like transuranic elements, because the doses to individual cells differ more widely than the range of doses over which the dose-response relationship can be regarded as linear. We intend to make up a three-dimensional model of parenchymal lung using a stack of actual histological sections in order to computer microscopic dose distribution around particulate α-emitters. This theoretical dosimetric approach will provide a scientific basis to the extrapolation of results of animal experiments utilizing high doses to man exposed to low level radioactivity and also to the understanding of biological effects associated with high LET radiations. Lung cells which survive α-particle hits were calculated, which will be a significant index of potential risk. Three models were assumed for the structure of parenchymal lung, which were 1) structureless lung of uniform density, 2) lattice of honeycomb pattern and 3) digital image of actual histological section of rat lung. The result shows that the survival cells decrease exponentially with the diameter of inhaled particles in any models. But the slope of the curve for the structureless lung is much greater than those for any other two models. This result suggests the validity of the dosimetric approach using actual histological section to estimate the inhalation risk of particulate α-emitters. (author)

  5. The impact of fuel particle size distribution on neutron transport in stochastic media

    International Nuclear Information System (INIS)

    This paper presents a study of the particle size distribution impact on neutron transport in three-dimensional stochastic media. An eigenvalue problem is simulated in a cylindrical container consisting of fissile fuel particles with five different size distributions: constant, uniform, power, exponential and Gaussian. We construct 15 cases by altering the fissile particle volume packing fraction and its optical thickness, but keeping the mean chord length of the spherical fuel particle the same at different size distributions. The tallied effective multiplication factor (keff) and flux distribution along axial and radial directions are compared between different size distributions. At low packing fraction and low optical thickness, the size distribution has a significant impact on radiation transport in stochastic media, which can cause as high as ∼270 pcm difference in keff value and ∼2.6% relative error difference in peak flux. As the packing fraction and optical thickness increase, the impact gradually dissipates. (authors)

  6. NUMBER CONCENTRATION, SIZE DISTRIBUTION AND FINE PARTICLE FRACTION OF TROPOSPHERIC AND STRATOSPHERIC AEROSOLS

    Institute of Scientific and Technical Information of China (English)

    Li Xu; Guangyu Shi; Li Zhang; Jun Zhou; Yasunobu Iwasaka

    2003-01-01

    Aerosol observations were carried out at Xianghe Scientific Balloon Base (39.45°N, 117°E) using a stratospheric balloon. The particle number concentrations of the tropospheric and stratospheric aerosols were directly explored.The vertical distributions of the number concentration, number-size (that is, particle number versus particle size)distribution, and the fraction of fine particles (0.5 μm>r>0.15 μm/r>0.15 μm) are reported in this paper. The profiles of particle concentration present multi-peak phenomenon. The pattern of size distribution for atmospheric aerosol indicates a tri-modal (r=~0.2 μm, ~0.88 μm and ~7.0 μm) and a bi-modal (r=~0.13 μm and 2.0 μm). The number-size distribution almost fits the Junge distribution for particles with r<0.5 μm in the stratosphere of 1993 and the troposphere of 1994. But the distributions of coarse particles (r>0.5 μm) are not uniform. The number-size distribution exhibits also a wide size range in the troposphere of 1993. The results demonstrate that fine particles represent the major portion in the troposphere during the measurement period, reaching as high as 95% in 1994. Certain coarse particle peaks in the troposphere were attributed to clouds and other causes, and in the stratosphere to volcanic eruption. The stratospheric aerosol layer consists of unique fractions of fine or coarse particles depending on their sources. In summary, the process of gas-to-particles conversion was active and the coarse particles were rich over the Xianghe area. The measurements also demonstrate that the spatial and temporal atmospheric aerosol distributions are nonuniform and changeful.

  7. Ti particle-reinforced surface layers in Al: Effect of particle size on microstructure, hardness and wear

    Energy Technology Data Exchange (ETDEWEB)

    Mordyuk, B.N., E-mail: mordyuk@imp.kiev.ua [Kurdyumov Institute for Metal Physics, 36 Academician Vernadsky Boulevard, UA-03680, Kyiv (Ukraine); Silberschmidt, V.V. [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, LE11 3TU (United Kingdom); Prokopenko, G.I. [Kurdyumov Institute for Metal Physics, 36 Academician Vernadsky Boulevard, UA-03680, Kyiv (Ukraine); Nesterenko, Yu.V. [National Technical University ' Kyiv Polytechnic Institute' , 37 Peremohy Avenue, UA-03056, Kyiv (Ukraine); Iefimov, M.O. [Frantzevich Institute for Problems of Materials Science, 3 Krzhyzhanivsky Street, UA-03142, Kyiv (Ukraine)

    2010-11-15

    Two types of Ti particles are used in an ultrasonic impact peening (UIP) process to modify sub-surface layers of cp aluminium atomized, with an average size of approx. 20 {mu}m and milled (0.3-0.5 {mu}m). They are introduced into a zone of severe plastic deformation induced by UIP. The effect of Ti particles of different sizes on microstructure, phase composition, microhardness and wear resistance of sub-surface composite layers in aluminium is studied in this paper. The formed layers of a composite reinforced with smaller particles have a highly misoriented fine-grain microstructure of its matrix with a mean grain size of 200-400 nm, while reinforcement with larger particles results in relatively large Al grains (1-2 {mu}m). XRD, SEM, EDX and TEM studies confirm significantly higher particle/matrix bonding in the former case due to formation of a Ti{sub 3}Al interlayer around Ti particles with rough surface caused by milling. Different microstructures determine hardness and wear resistance of reinforced aluminium layers: while higher magnitudes of microhardness are observed for both composites (when compared with those of annealed and UIP-treated aluminium), the wear resistance is improved only in the case of reinforcement with small particles.

  8. Ti particle-reinforced surface layers in Al: Effect of particle size on microstructure, hardness and wear

    International Nuclear Information System (INIS)

    Two types of Ti particles are used in an ultrasonic impact peening (UIP) process to modify sub-surface layers of cp aluminium atomized, with an average size of approx. 20 μm and milled (0.3-0.5 μm). They are introduced into a zone of severe plastic deformation induced by UIP. The effect of Ti particles of different sizes on microstructure, phase composition, microhardness and wear resistance of sub-surface composite layers in aluminium is studied in this paper. The formed layers of a composite reinforced with smaller particles have a highly misoriented fine-grain microstructure of its matrix with a mean grain size of 200-400 nm, while reinforcement with larger particles results in relatively large Al grains (1-2 μm). XRD, SEM, EDX and TEM studies confirm significantly higher particle/matrix bonding in the former case due to formation of a Ti3Al interlayer around Ti particles with rough surface caused by milling. Different microstructures determine hardness and wear resistance of reinforced aluminium layers: while higher magnitudes of microhardness are observed for both composites (when compared with those of annealed and UIP-treated aluminium), the wear resistance is improved only in the case of reinforcement with small particles.

  9. The effect of particle size on fracture properties and size effect of concrete

    NARCIS (Netherlands)

    Schlangen, E.; Lim, H.S.; Weerheijm, J.

    2005-01-01

    In the study the effect of scaling the material structure on the fracture behaviour of concrete is investigated. Next to this the size effect of concrete fracture strength and fracture energy is studied. The fracture mechanism of concrete made with different size aggregates are tested numerically. A

  10. The effect of particle size on hydrolysis reaction rates and rheological properties in cellulosic slurries.

    Science.gov (United States)

    Dasari, Rajesh K; Eric Berson, R

    2007-04-01

    The effect of varying initial particle sizes on enzymatic hydrolysis rates and rheological properties of sawdust slurries is investigated. Slurries with four particle size ranges (33 microm units per gram of cellulose at 50 degrees C and 250 rpm in shaker flasks. At lower initial particle sizes, higher enzymatic reaction rates and conversions of cellulose to glucose were observed. After 72 h 50 and 55% more glucose was produced from the smallest size particles than the largest size ones, for initial solids concentration of 10 and 13% (w/w), respectively. The effect of initial particle size on viscosity over a range of shear was also investigated. For equivalent initial solids concentration, smaller particle sizes result in lower viscosities such that at a concentration of 10% (w/w), the viscosity decreased from 3000 cP for 150 microm conversion of biomass to ethanol. Furthermore, the corresponding reduction in viscosity may allow for higher solids loading and reduced reactor sizes during large-scale processing. PMID:18478396

  11. Composition and mutagenicity of PAHs associated with urban airborne particles in Córdoba, Argentina

    International Nuclear Information System (INIS)

    The comet assay and micronucleous test were used to assess the genotoxicity of organic compounds associated with particulate material collected in the city of Córdoba, Argentina. Samples were collected on fiber glass filters and their organic extracts were analyzed by GC-MS. These extracts were used for the comet assay on human lymphocytes and for the MCN test with Tradescantia pallida. The concentrations of polycyclic aromatic hydrocarbons as well as some of their nitro derivates were higher during winter. Their composition suggested that their main emission sources were gasoline and diesel vehicles. We observed genotoxic effects of these organic extracts due to the presence of both direct and indirect acting mutagens. We found a good agreement between the two test systems employed, which encourages the further use of plant bioassays for air pollution monitoring, especially in developing countries, due to their flexibility, low cost and efficiency. -- Highlights: •PAHs and nitro-PAHs were higher during winter and fall seasons. •Concentrations of PAHs were below the daily potential dose of carcinogenic PAH. •The comet assay revealed that indirect mutagens were more abundant than direct ones. •The MCN test and the comet assay demonstrated the presence of human carcinogens. -- Capsule: Indirect mutagens were more abundant during winter and fall, in agreement with the higher concentrations of PAHs and nitro-PAHs being associated with atmospheric particles

  12. Limitations in the Use of Unipolar Charging for Electrical Mobility Sizing Instruments: A Study of the Fast Mobility Particle Sizer

    DEFF Research Database (Denmark)

    Levin, Marcus; Gudmundsson, A.; Pagels, J. H.;

    2015-01-01

    A comparison between three different types of particle sizing instruments (fast mobility particle sizer, FMPS; electrical low pressure impactor, ELPI; and scanning mobility particle sizer, SMPS) and one condensation particle counter (CPC) was made to compare instrument response in terms of size...... distributions and number concentration. Spherical oil droplets in 39 different sizes, with geometric mean diameter (GMD) ranging from 50nm to 820nm, were used as test particles. Furthermore, a characterization of the FMPS unipolar charger behavior was made to analyze the measured size distributions and number...... concentrations. The results show that all three sizing-instruments agree well for particle sizes below 200nm, both in terms of size and number concentration, but the FMPS deviates clearly when particle sizes exceed 200nm. Above this, the FMPS underestimates the particle size throughout the remainder of the size...

  13. Based on particle size distribution of radioactive aerosol of screen diffusion battery measuring software

    International Nuclear Information System (INIS)

    Based on screen diffusion battery of particle size distribution of the radioactive aerosol measuring system developed a measurement and analysis software, the software operating environment was the embedded ARM-based hardware system and embedded linux operating system. The software is developed by the open source package QT. System functions included the measurement process control, screen diffusion battery transmittance calculations, particle size distribution measurement, measurement data analysed by the EM algorithm and Twomey algorithms, particle size distribution showed, system communication and other functions. (authors)

  14. Measurements of Particle Size Distribution Based on Mie Scattering Theory and Markov Chain Inversion Algorithm

    Directory of Open Access Journals (Sweden)

    Zi Ye

    2012-10-01

    Full Text Available Measuring particle size distribution through calculating light scattering intensity is a typical inverse problem. This paper builds an inverse mathematical model based on Mie scattering, deduces the inversion formulas for particle size, and calculates the relative coefficients through programming with built-in functions in MATLAB. In order to improve the accuracy and noise immunity of particle size distribution measurement, the development of stochastic inversion algorithm: an inverse problem model based on Markov chain algorithm is proposed. Results of numerical simulation are added acceptable noise indicate that the algorithm of Markov chain has strong noise immunity and can meet the requirements of on-line measurement.

  15. Effect of particle size and temperature on volatiles produced from coal by slow pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Morris, R.M. (University of Durban-Westville, Durban (South Africa). Dept. of Chemical Engineering)

    1990-06-01

    Pyrolysis runs were carried out in the temperature range 1000-1150{degree}C and the particle size range +38 {mu}m to -2360{mu}m on a semianthracite coal from the Welgedacht area. Correlations were established for the yields of hydrogen and methane as functions of particle size and final temperature, and for carbon monoxide and carbon dioxide as a function of particle size at a final temperature before decomposition of carbonates in the mineral matter. The observations are explained in terms of secondary reactions occurring in the diffusion of the primary products through the pores of the char. 10 refs., 6 figs., 4 tabs.

  16. Size measurement of nano-particles using self-mixing effect

    Institute of Scientific and Technical Information of China (English)

    Huarui Wang; Jianqi Shen

    2008-01-01

    In this letter, the technique of laser self-mixing effect is employed for nano-particle size analysis. In contrast to the photon correlation spectroscopy (PCS) and photon cross correlation spectroscopy (PCCS),the main advantages of this technique are sensitive, compact, low-cost, and simple experimental setup etc.An improved Kaczmarz projection method is developed in the inversion problem to extract the particle size distribution. The experimental results prove that nano-particle size can be measured reasonably by using the self-mixing effect technique combined with the improved projection algorithm.

  17. Atomic-Scale Modeling of Particle Size Effects for the Oxygen Reduction Reaction of Pt

    DEFF Research Database (Denmark)

    Tritsaris, Georgios; Greeley, Jeffrey Philip; Rossmeisl, Jan;

    2011-01-01

    both the specific and mass activities for particle sizes in the range between 2 and 30 nm. The mass activity is calculated to be maximized for particles of a diameter between 2 and 4 nm. Our study demonstrates how an atomic-scale description of the surface microstructure is a key component in...... understanding particle size effects on the activity of catalytic nanoparticles.......We estimate the activity of the oxygen reduction reaction on platinum nanoparticles of sizes of practical importance. The proposed model explicitly accounts for surface irregularities and their effect on the activity of neighboring sites. The model reproduces the experimentally observed trends in...

  18. Faecal particle-size distribution from ewes fed grass silages harvested at different stages of maturity

    DEFF Research Database (Denmark)

    Jalali, Alireza; Nørgaard, Peder; Nadeau, E.;

    2008-01-01

    The aim of this experiment was to study the effect of maturity stage of grass at harvest on particle size in faeces from ewes fed grass silage ad libitum. Eighteen pregnant Swedish ewes bearing two foetuses were given one of three treatments as their only feed. The treatments were early (ECS...... pore size. The proportions of particles in the B, C, D, S and O fractions were affected by cutting time of the silaage (P < 0.003). In conclusion, stage of maturity at harvest strongly affects the distribution of particle size in faeces from ewes fed grass silages....

  19. Laser tweezers: spectroscopy of optically trapped micron-sized particles

    International Nuclear Information System (INIS)

    Information is often obtained about biological systems by analysis of single cells in the system. The optimum conditions for this analysis are when the cells are living and in their natural surroundings as they will be performing their normal functions and interactions. Analysis of cells can be difficult due to their mobility. Laser tweezing is a non contact method that can be employed to overcome this problem and provides a powerful tool in the analysis of functions and interactions at single cell level. In this investigation Raman spectra of a molecule of β - carotene, dissolved in microdroplets of oil was obtained. The droplets were trapped using Nd-YAG beam and a low intensity Ar+ beam was used to analyse the trapped particles. 2 refs., 5 figs

  20. Laser tweezers: spectroscopy of optically trapped micron-sized particles

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, K.M.; Livett, M.K.; Nugent, K.W. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1996-12-31

    Information is often obtained about biological systems by analysis of single cells in the system. The optimum conditions for this analysis are when the cells are living and in their natural surroundings as they will be performing their normal functions and interactions. Analysis of cells can be difficult due to their mobility. Laser tweezing is a non contact method that can be employed to overcome this problem and provides a powerful tool in the analysis of functions and interactions at single cell level. In this investigation Raman spectra of a molecule of {beta} - carotene, dissolved in microdroplets of oil was obtained. The droplets were trapped using Nd-YAG beam and a low intensity Ar{sup +} beam was used to analyse the trapped particles. 2 refs., 5 figs.

  1. SIZE DISTRIBUTIONS OF SOLAR FLARES AND SOLAR ENERGETIC PARTICLE EVENTS

    Energy Technology Data Exchange (ETDEWEB)

    Cliver, E. W. [Space Vehicles Directorate, Air Force Research Laboratory, Sunspot, NM 88349 (United States); Ling, A. G. [Atmospheric Environmental Research, Lexington, MA 02421 (United States); Belov, A. [IZMIRAN, Troitsk, Moscow Region 142190 (Russian Federation); Yashiro, S. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-09-10

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast ({>=}1000 km s{sup -1}) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes ({alpha} values) of power-law size distributions of the peak 1-8 A fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes {>=}1 pr cm{sup -2} s{sup -1} sr{sup -1}) and (b) fast CMEs were {approx}1.3-1.4 compared to {approx}1.2 for the peak proton fluxes of >10 MeV SEP events and {approx}2 for the peak 1-8 A fluxes of all SXR flares. The difference of {approx}0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  2. SIZE DISTRIBUTIONS OF SOLAR FLARES AND SOLAR ENERGETIC PARTICLE EVENTS

    International Nuclear Information System (INIS)

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (≥1000 km s–1) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (α values) of power-law size distributions of the peak 1-8 Å fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes ≥1 pr cm–2 s–1 sr–1) and (b) fast CMEs were ∼1.3-1.4 compared to ∼1.2 for the peak proton fluxes of >10 MeV SEP events and ∼2 for the peak 1-8 Å fluxes of all SXR flares. The difference of ∼0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  3. An optical particle size spectrometer for aircraft-borne measurements in IAGOS-CARIBIC

    Science.gov (United States)

    Hermann, Markus; Weigelt, Andreas; Assmann, Denise; Pfeifer, Sascha; Muller, Thomas; Conrath, Thomas; Voigtlander, Jens; Heintzenberg, Jost; Wiedensohler, Alfred; Martinsson, Bengt G.; Deshler, Terry; Brenninkmeijer, Carl A. M.; Zahn, Andreas

    2016-05-01

    The particle number size distribution is an important parameter to characterize the atmospheric aerosol and its influence on the Earth's climate. Here we describe a new optical particle size spectrometer (OPSS) for measurements of the accumulation mode particle number size distribution in the tropopause region on board a passenger aircraft (IAGOS-CARIBIC observatory: In-service Aircraft for a Global Observing System - Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container). A modified KS93 particle sensor from RION Co., Ltd., together with a new airflow system and a dedicated data acquisition system, is the key component of the CARIBIC OPSS. The instrument records individual particle pulse signal curves in the particle size range 130-1110 nm diameter (for a particle refractive index of 1.47-i0.006) together with a time stamp and thus allows the post-flight choice of the time resolution and the size distribution bin width. The CARIBIC OPSS has a 50 % particle detection diameter of 152 nm and a maximum asymptotic counting efficiency of 98 %. The instrument's measurement performance shows no pressure dependency and no particle coincidence for free tropospheric conditions. The size response function of the CARIBIC OPSS was obtained by a polystyrene latex calibration in combination with model calculations. Particle number size distributions measured with the new OPSS in the lowermost stratosphere agreed within a factor of 2 in concentration with balloon-borne measurements over western North America. Since June 2010 the CARIBIC OPSS is deployed once per month in the IAGOS-CARIBIC observatory.

  4. Influence of Particle Size on Magnetic Properties of Soils in Zhejiang Province, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The relationship between magnetic properties and particle size of soils derived from metamorphic rock,basalt, granite, Quaternary red clay, limestone and mudstone from Zhejiang Province, East China was stu died. Based on the variations of the mass magnetic susceptibility (x), anhysteretic remanent magnetization (ARM), and saturation isothermal remanent magnetizatization (SIRM) with soil particle size, the relationship could be classified into three groups. For the soils derived from metamorphic rock and basalt, magnetic values were the highest in the gravel and coarse sand fractions and decreased with decreasing soil particle size. The soils derived from sedimentary rock had a bimodal distribution of magnetic values, with peaks in 1~0.5 and 0.005~0.000 5 mm fractions. The soil developed on granite was characterized by a peak of magnetic valuein 0.001~0.000 5 mm fractions. Frequency-dependent susceptibility (xfd) and ratios of magnetic parameters (ARM/x, SIRM/x and SIRM/ARM) of soil particle fractions showed that variations in ferrimagnetic grainsize paralleled those in particle size. xfd peaked in clay fraction and decreased with increasing particle size,irrespective of soil parent materials. The acquisition curves of IRM and demagnetization parameter of different soil particles indicated that there were different agnetic minerals assemblages in different particle fractions..

  5. Seasonal cycle and modal structure of particle number size distribution at Dome C, Antarctica

    Directory of Open Access Journals (Sweden)

    E. Järvinen

    2013-08-01

    Full Text Available We studied new particle formation and modal behavior of ultrafine aerosol particles on the high East Antarctic plateau at the Concordia station, Dome C (75°06' S, 123°23' E. Aerosol particle number size distributions were measured in the size range 10–600 nm from 14 December 2007 to 7 November 2009. We used an automatic algorithm for fitting up to three modes to the size distribution data. The total particle number concentration was low with the median of 109 cm−3. There was a clear seasonal cycle in the total particle number and the volume concentrations. The concentrations were at their highest during the austral summer with the median values of 260 cm−3 and 0.086 μm3 cm−3, and at their lowest during the austral winter with corresponding values of 15 cm−3 and 0.009 μm3 cm−3. New particle formation events were determined from the size distribution data. During the measurement period, natural new particle formation was observed on 60 days and for 15 of these days the particle growth rates from 10 to 25 nm in size could be determined. The median particle growth rate during all these events was 2.5 nm h−1 and the median formation rate of 10 nm particles was 0.023 cm−3 s−1. Most of the events were similar to those observed at other continental locations, yet also some variability in event types was observed. Exceptional features in Dome C were the winter events that occurred during dark periods, as well as the events for which the growth could be followed during several consecutive days. We called these latter events slowly growing events. This paper is the first one to analyze long-term size distribution data from Dome C, and also the first paper to show that new particle formation events occur in central Antarctica.

  6. Narrowly size-distributed cobalt salt containing poly(2-hydroxyethyl methacrylate) particles by inverse miniemulsion.

    Science.gov (United States)

    Cao, Zhihai; Wang, Zhuo; Herrmann, Christine; Ziener, Ulrich; Landfester, Katharina

    2010-05-18

    Cobalt-containing hybrid particles have been prepared through the encapsulation of cobalt tetrafluoroborate hexahydrate (CoTFB) via inverse miniemulsion polymerization of 2-hydroxyethyl methacrylate (HEMA). We systematically varied the amount and type of cosolvent (water, methanol, ethanol, ethylene glycol), apolar continuous phase (cyclohexane, isooctane, isopar M, hexadecane), amount of cobalt salt, and molecular weight of the polymeric surfactant. The influence of those parameters on the particle size, size distribution, and particle morphology were investigated. Narrowly size-distributed hybrid particles with good colloidal stability could be obtained in a wide range of cobalt content between 5.7 and 22.6 wt % salt relative to the monomer. The addition of a cosolvent such as water not only promotes the loading of metal salt but also has a positive influence on narrowing the particle size distribution. We assume that generally narrowly size-distributed particles can be obtained for a large variety of combinations of polar/apolar phase by adjusting the balance between osmotic and Laplace pressure via the solubility of the metal salt in the continuous phase and lowering the interfacial tension by adjusting the hydrophilic-lipophilic balance (HLB) value of the surfactant. The results show a significant advantage of the inverse miniemulsion over the direct system with respect to the variability and total amount of metal salt without losing the narrow particle size distribution and colloidal stability. PMID:20112941

  7. Preparation and characterization of micrometer-sized ice particles for planetary-science experiments

    CERN Document Server

    Gundlach, Bastian; Beitz, Eike; Blum, Jürgen

    2011-01-01

    Coagulation models assume a higher sticking threshold for micrometer-sized ice particles than for micrometer-sized silicate particles. However, in contrast to silicates, laboratory investigations of the collision properties of micrometer-sized ice particles (in particular, of the most abundant water ice) have not been conducted yet. Thus, we established two different experimental methods to produce micrometer-sized water ice particles, i. e. by spraying water droplets into liquid nitrogen an by spraying water droplets into a cold nitrogen atmosphere. We found that the size of the ice particles, produced with the different methods, are very similar (arithmetic means of the particle radii for the two different methods: (1.49+-0.79) micrometer and (1.45+-0.65) micrometer, respectively). Ice aggregates composed of the micrometer-sized ice particles are highly porous (volume filling factor: 0.11+-0.01) or rather compact (volume filling factor: 0.72+-0.04), depending on the method of production. Furthermore, a roll...

  8. Investigation of aged aerosols in size-resolved Asian dust storm particles transported from Beijing, China to Incheon, Korea using low-Z particle EPMA

    Directory of Open Access Journals (Sweden)

    H. Geng

    2013-10-01

    Full Text Available This is the first study of Asian dust storm (ADS particles collected in Beijing, China and Incheon, Korea during the same spring ADS event. Using a seven-stage May impactor and a quantitative electron probe X-ray microanalysis (ED-EPMA, also known as low-Z particle EPMA, we examined the composition and morphology of 4200 aerosol particles at stages 1–6 (with a size cut-off of 16, 8, 4, 2, 1, and 0.5 μm in equivalent aerodynamic diameter, respectively collected during an ADS event on 28–29 April 2005. The results showed that there were large differences in the chemical compositions between particles in sample S1 collected in Beijing immediately after the peak time of the ADS and in samples S2 and S3, which were collected in Incheon approximately 5 h and 24 h later, respectively. In sample S1, mineral dust particles accounted for more than 88% in relative number abundance at stages 1–5, and organic carbon (OC and reacted NaCl-containing particles accounted for 24% and 32%, respectively, at stage 6. On the other hand, in samples S2 and S3, in addition to approximately 60% mineral dust, many sea salt particles reacted with airborne SO2 and NOx, often mixed with mineral dust, were encountered at stages 1–5, and (C, N, O, S-rich particles (likely a mixture of water-soluble organic carbon with (NH42SO4 and NH4NO3 and K-containing particles were abundantly observed at stage 6. This suggests that the secondary aerosols and the internal mixture of mineral dust with sea spray aerosol increased when the ADS particles passed over the Yellow Sea. In the reacted or aged mineral dust and sea salt particles, nitrate-containing and both nitrate- and sulfate-containing species vastly outnumbered the sulfate-containing species, implying that ambient nitrogen oxides had a greater influence on the atmospheric particles during the ADS episode than SO2. In addition to partially- or totally-reacted CaCO3, reacted or aged Mg-containing aluminosilicates (likely

  9. Fundamental study on laser manipulation of contamination particles with determining shape, size and species

    International Nuclear Information System (INIS)

    It has been desired to eliminate or collect the contamination particles of radioisotope in each sort of species or shape and size non-invasively. The shape and size of particle can be determined from the shape and distribution of diffraction pattern of particle in the parallel laser beam, the species of particle can be discriminated by the fluorescence from resonance of laser beam, or by the laser Raman scattering, and the particle suspended in the air or falling down in a vacuum can be levitated against the gravity and trapped by the radiation force and the trapping force of the focussed laser beam in the atmosphere or in a vacuum. For the purpose of the non-invasive manipulation of contamination particles, the laser manipulation technique, image processing technique with Multiplexed Matched Spatial Filter and the determination technique of laser Raman scattering or fluorescence from resonance of laser light were combined in the experiments. The shape, size and species of particles trapped in the focal plane of focused Ar laser beam can be determined simultaneously and instantaneously from the shape and intensity distributions of diffraction patterns of the particles in the irradiation of parallel coherent beam of He-Ne laser, and fluorescence from the resonance of YAG laser beam with variable wave length. In this research, a new technique is proposed to manipulate non-invasively the contamination particles determined with the shape, size and species in the atmosphere or in a vacuum, by laser beam. (author)

  10. (99m)Tc-human serum albumin nanocolloids: particle sizing and radioactivity distribution.

    Science.gov (United States)

    Persico, Marco G; Lodola, Lorenzo; Buroni, Federica E; Morandotti, Marco; Pallavicini, Piersandro; Aprile, Carlo

    2015-07-01

    Several parameters affect the biodistribution of administered nanocolloids (NC) for Sentinel Lymph Node (SLN) detection: particle size distribution, number of Tc atoms per particle and specific activity (SA). Relatively few data are available with frequently conflicting results. (99m)Tc-NC-human serum albumin (HSA) Nanocoll®, Nanoalbumon® and Nanotop® were analysed for particles' dimensional and radioactivity distribution, and a mathematical model was elaborated to estimate the number of particles involved. Commercially available kits were reconstituted at maximal SA of 11 MBq/µg HSA. Particles size distribution was evaluated by Dynamic Light Scattering. These data were related to the radioactivity distribution analysis passing labelled NC through three polycarbonate filters (15-30-50-nm pore size) under vacuum. Highest radioactivity was carried by 30-50 nm particles. The smallest ones, even though most numerous, carried only the 10% of (99m)Tc atoms. Nanocoll and Nanotop are not significantly different, while Nanoalbumon is characterized by largest particles (>30 nm) that carried the most of radioactivity (80%). Smallest particles could saturate the clearing capacity of macrophages; therefore, if the tracer is used for SLN detection, more node tiers could be visualized, reducing accuracy of SLN mapping. Manufacturers could implement technical leaflets with particle size distribution and could improve the labelling protocol to provide clinicians useful information. PMID:26198778

  11. Critical conditions for particle motion in coarse bed materials of nonuniform size distribution

    Science.gov (United States)

    Bathurst, James C.

    2013-09-01

    Initiation of particle motion in a bed material of nonuniform size distribution may be quantified by (qci/qcr) = (Di/Dr)b, where qci is the critical unit discharge at which particle size Di enters motion, qcr is the critical condition for a reference size Dr unaffected by the hiding/exposure effects associated with nonuniform size distributions, i and r refer to percentiles of the distribution and b varies from 0 (equal mobility in entrainment of all particle sizes) to 1.5-2.5 (full size selective transport). Currently there is no generally accepted method for predicting the value of b. Flume and field data are therefore combined to investigate the above relationship. Thirty-seven sets of flume data quantify the relationship between critical unit discharge and particle size for bed materials with uniform size distributions (used here to approximate full size selective transport). Field data quantify the relationship for bed materials of nonuniform size distribution at 24 sites, with b ranging from 0.15 to 1.3. Intersection of the two relationships clearly demonstrates the hiding/exposure effect; in some but not all cases, Dr is close to the median size D50. The exponent has two clusters of values: b > 1 for sites subject to episodic rain-fed floods and data collected by bedload pit trap and tracers; and b 1, sites with relatively infrequent bedload transport where particle embedding and consolidation could reduce the mobility of coarser particles; and, for b firm evidence for such a dependency on bed structure but variations in b could potentially be caused by factors outside those determining equal mobility or size selection but appearing to affect b in the same way.

  12. Values of Particle Size, Particle Density and Slurry Viscosity to use in Waste Feed Delivery Transfer System Analysis

    International Nuclear Information System (INIS)

    The objective of this document is to provide recommended values for three waste properties to be used in a planned revision of the Waste Feed Delivery Transfer System Analysis (Julyk et al. 2001). These properties are particle size distribution (PSD), particle density, and slurry viscosity. In this document, the results of laboratory and engineering studies will be collated and summarized to provide a succinct source of physical property data for use in the hydraulic analysis of the transfer system

  13. Particle size analysis of coal and lime stone used in fbc power plant lakhra

    International Nuclear Information System (INIS)

    Pakistan is gifted with huge coal reserves throughout its land from Sindh to NWFP province. The total reserves at Lakhra have been estimated to be 1328 million tones. Average annual production of coal from Lakhra is over one million tones. Most of this production is used in the WAPDA power plant at Khanot, Sindh and in brick kiln industry. The high sulphur content coal has been used in the FBC (Fluidized Bed Combustor) power plant at Lakhra. The coal and limestone have been used ill power plant at Lakhra are 52 and 26 tones/hr as per stoichiometric calculations respectively. The research shows that for complete combustion of high sulphur content coal and reducing the emission, the particles size of coal and limestone is of utmost importance. The particle sizes of coal and limestone have been analyzed. The result is then compared with the required particle size as per design parameters of FBC at Lakhra (coal and lime stone 13 and 6.0 mm). The result shows that the particle size of the coal and limestone is not being as per design parameter of the FBC. The coal and lime stone particles size used in FBC is from 0.075-4.75 that is much lower than the particle size of 13 and 6 mm as per design specification. In addition the particle size analysis was also carried out for the fly ash, bottom ash and re-injected material (un-burnt material from the FBC that is recycled to the FBC as per plant specification) to evaluate the overall performance of the FBC plant in terms of Maintenance and Operational problems. As a result of deviation of particle size of coal and limestone from the recommended size, the combustion of coal is not complete. The incomplete combustion not only reduces the plant efficiency and capacity but various operational and technical problems occurs that even result regular shut down of the power plant. (author)

  14. Preparation of Nano-Sized TiO2 Particles by Microemulsion Method

    Institute of Scientific and Technical Information of China (English)

    Shaohua Zhang; Bing Xie; Fengyi Li; Peng Xu

    2006-01-01

    Nano-sized titania powders have been prepared by hydrolysis of tetrabutyl titanate in the droplet of water/OP-7/pentanol/cyclohexane microemulsion system. The effects of ingredient change on the water drop size and particle size were investigated. The prepared TiO2 was in the form of anatase after annealing. TiO2 was characterized by TG-TGA,FTIR, XRD to measure the transformation temperature, surface adsorption and average size.

  15. Trace elements in airborne particles in internal industrial environments: spectrometric analysis of x-ray fluorescence (XRF)

    International Nuclear Information System (INIS)

    Fluorescence spectroscopy x-ray, is a technique of non-destructive analysis, that allows quantitative determination of the absolute concentration of chemical elements that make up a given matrix. The detected elements depend on atomic number and energy of the secondary target used for irradiation of samples. X-rays are detected and counted in a spectroscopy system based on a multichannel analyzer, that discriminates by energy and form a spectrum of independent photopeaks, whose energy identifies the element and its intensity is proportional to its concentration. The quantification requires the irradiation and counting of a set of pattern comparators, of the same elements identified in the samples. The x-ray emission shows only during the time that the selected sample is subjected to irradiation by x-ray tube. This irradiation does not change the structure nor the chemical composition of the matrix, so the sample remains unchanged, after irradiation. This condition non-destructive characterizes the fluorescence x-ray. The trace elements present in airborne particles, are determined and collected on a Nuclepore filter. The collection sites selected are: Taller de Mecanica de Precision de la Escuela de Fisica, Universidad de Costa Rica; Taller J. V. G. Precision, San Antonio de Coronado; Taller de Muflas, MUFLASA, Alto de Guadalupe; Industria Silvania S. A., Pavas. In addition, it is attached the service rendered to the enterprise Sellos Generales S. A. The working conditions and physical conditions of facilities were considered. An aerosol sampler with a temporal variation was used. Irradiation of samples and an evaluation of the concentrations have been made. (author)

  16. The impact of flood and post-flood cleaning on airborne microbiological and particle contamination in residential houses.

    Science.gov (United States)

    He, Congrong; Salonen, Heidi; Ling, Xuan; Crilley, Leigh; Jayasundara, Nadeesha; Cheung, Hing Cho; Hargreaves, Megan; Huygens, Flavia; Knibbs, Luke D; Ayoko, Godwin A; Morawska, Lidia

    2014-08-01

    In January 2011, Brisbane, Australia, experienced a major river flooding event. We aimed to investigate its effects on air quality and assess the role of prompt cleaning activities in reducing the airborne exposure risk. A comprehensive, multi-parameter indoor and outdoor measurement campaign was conducted in 41 residential houses, 2 and 6 months after the flood. The median indoor air concentrations of supermicrometer particle number (PN), PM10, fungi and bacteria 2 months after the flood were comparable to those previously measured in Brisbane. These were 2.88 p cm(-3), 15 μg m(-3), 804 cf um(-3) and 177 cf um(-3) for flood-affected houses (AFH), and 2.74 p cm(-3), 15 μg m(-3), 547 cf um(-3) and 167 cf um(-3) for non-affected houses (NFH), respectively. The I/O (indoor/outdoor) ratios of these pollutants were 1.08, 1.38, 0.74 and 1.76 for AFH and 1.03, 1.32, 0.83 and 2.17 for NFH, respectively. The average of total elements (together with transition metals) in indoor dust was 2296 ± 1328 μg m(-2) for AFH and 1454 ± 678 μg m(-2) for NFH, respectively. In general, the differences between AFH and NFH were not statistically significant, implying the absence of a measureable effect on air quality from the flood. We postulate that this was due to the very swift and effective cleaning of the flooded houses by 60,000 volunteers. Among the various cleaning methods, the use of both detergent and bleach was the most efficient at controlling indoor bacteria. All cleaning methods were equally effective for indoor fungi. This study provides quantitative evidence of the significant impact of immediate post-flood cleaning on mitigating the effects of flooding on indoor bioaerosol contamination and other pollutants. PMID:24785990

  17. [Particle Size and Number Density Online Analysis for Particle Suspension with Polarization-Differentiation Elastic Light Scattering Spectroscopy].

    Science.gov (United States)

    Chen, Wei-kang; Fang, Hui

    2016-03-01

    The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products. PMID:27400522

  18. Removal of Cryptosporidium sized particle under different filtration temperature, flow rate and alum dosing

    Institute of Scientific and Technical Information of China (English)

    XU Guo-ren; Fitzpatrick S. B. Caroline; Gregory John; DENG Lin-yu

    2007-01-01

    Recent Cryptosporidium outbreaks have highlighted concerns about filter efficiency and in particular particle breakthrough. It is essential to ascertain the causes of Cryptosporidium sized particle breakthrough for Cryptosporidium cannot be destroyed by conventional chlorine disinfection. This research tried to investigate the influence of temperature, flow rate and chemical dosing on particle breakthrough during filtration. The results showed that higher temperatures and coagulant doses could reduce particle breakthrough. The increase of filtration rate made the residual particle counts become larger. There was an optimal dose in filtration and was well correlated to ζ potential.

  19. Characterization of macromolecular complexes in red wine: Composition, molecular mass distribution and particle size.

    Science.gov (United States)

    Bindon, Keren A; Carew, Anna L; Mierczynska-Vasilev, Agnieszka; Kassara, Stella; Kerslake, Fiona; Smith, Paul A

    2016-05-15

    Precipitates were prepared from two compositionally different Pinot noir wines with addition of excess ethanol, and contained primarily polysaccharide, tannin and protein. The ethanol-soluble material was further fractionated into polymeric (tannin) and monomeric phenolics. Tannin associated with precipitates was of a higher molecular mass than that remaining in ethanolic solution. Wine fractions were reconstituted at the ratios of the original wine and analyzed using nanoparticle tracking analysis. The average particle size of the tannin fraction was 75-89 nm, and increased when combined with the precipitate (≅ 200 nm). Addition of the monomeric fraction to the tannin-precipitate complex increased both the incidence and concentration of smaller particles, reducing the average particle size. The formation of aggregates occurred in all fractions and only minor differences in particle size distribution were found between wines. Differences in particle concentration between wines appear to be due to differences in the total concentration of macromolecules rather than compositional differences. PMID:26776042

  20. The effect of particle size distributions on the microstructural evolution during sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Tikare, V.; Frandsen, Henrik Lund;

    2013-01-01

    Microstructural evolution and sintering behavior of powder compacts composed of spherical particles with different particle size distributions (PSDs) were simulated using a kinetic Monte Carlo model of solid state sintering. Compacts of monosized particles, normal PSDs with fixed mean particle...... PSDs, but the final grain sizes were smaller. These behaviors are explained by the smallest grains in the broader PSDs being consumed very quickly by larger neighboring grains. The elimination of the small grains reduces both the total number of necks and the neck area between particles, which in turn...... reduces the regions where vacancies can be annihilated, leading to slower densification rates. The loss of neck area causes grain growth by surface diffusion to become the dominant microstructural evolution mechanism, leading to poor densification. Finally, pore size was shown to increase with the width...

  1. Studies on the Effects of RDX Particle Size on the Burning Rate of Gun Propellants

    Directory of Open Access Journals (Sweden)

    A.G.S. Pillai

    1996-04-01

    Full Text Available The ballistic properties of RDX-based propellants are highly dependent on the particle size of RDX used. The effect of RDX particle size on the burning rate and pressure exponent of the gun propellant was studied. Propellant formulation containing RDX to extent of 60 per cent in the composition was processed with varying particle size of RDX. Finished propellants in heptatubular and cord geometry were evaluated for ballistic aspects by closed vessel firing in a 700 cc vessel at a loading density of 0.18 g/cc. The data obtained clearly indicate that increase in particle size of RDX increases the burning rate as well as the pressure exponent.

  2. Particle Size Distribution, Powder Agglomerates and Their Effects on Sinterability of Ultrafine Alumina Powders

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An intensive study of the particle size distribution of four commercial ultrafine alumina powders to obtain information about the powder agglomeration and relate them to the compactibility and the sinterability has been made.

  3. Regression modeling of particle size distributions in urban storm water: advancements through improved sample collection methods

    Science.gov (United States)

    Fienen, Michael N.; Selbig, William R.

    2012-01-01

    A new sample collection system was developed to improve the representation of sediment entrained in urban storm water by integrating water quality samples from the entire water column. The depth-integrated sampler arm (DISA) was able to mitigate sediment stratification bias in storm water, thereby improving the characterization of suspended-sediment concentration and particle size distribution at three independent study locations. Use of the DISA decreased variability, which improved statistical regression to predict particle size distribution using surrogate environmental parameters, such as precipitation depth and intensity. The performance of this statistical modeling technique was compared to results using traditional fixed-point sampling methods and was found to perform better. When environmental parameters can be used to predict particle size distributions, environmental managers have more options when characterizing concentrations, loads, and particle size distributions in urban runoff.

  4. Size-selective separation of DNA fragments by using lysine-functionalized silica particles

    Science.gov (United States)

    Liu, Lingling; Guo, Zilong; Huang, Zhenzhen; Zhuang, Jiaqi; Yang, Wensheng

    2016-02-01

    In this work, a facile and efficient approach has been demonstrated for size-selective separation of DNA fragments by using lysine-functionalized silica particles. At a given pH, the environmental ionic strength can be utilized to alter the electrostatic interactions of lysine-functionalized silica particles with DNA fragments and in turn the DNA fragments on the silica particle surfaces, which exhibits a clear dependence on the DNA fragment sizes. By carefully adjusting the environmental pH and salt concentration, therefore, the use of the lysine-functionalized silica particles allows effective separation of binary and ternary DNA mixtures, for example, two different DNA fragments with sizes of 101 and 1073 bp, 101 and 745 bp, 101 and 408 bp, respectively, and three different DNA fragments with sizes of 101, 408 and 1073 bp.

  5. Electromechanical characterization of individual micron-sized metal coated polymer particles

    Science.gov (United States)

    Bazilchuk, Molly; Pettersen, Sigurd Rolland; Kristiansen, Helge; Zhang, Zhiliang; He, Jianying

    2016-06-01

    Micron-sized polymer particles with nanoscale metal coatings are essential in conductive adhesives for electronics assembly. The particles function in a compressed state in the adhesives. The link between mechanical properties and electrical conductivity is thus of the utmost importance in the formation of good electrical contact. A custom flat punch set-up based on nanoindentation has been developed to simultaneously deform and electrically probe individual particles. The set-up has a sufficiently low internal resistance to allow the measurement of sub-Ohm contact resistances. Additionally, the set-up can capture mechanical failure of the particles. Combining this data yields a fundamental understanding of contact behavior. We demonstrate that this method can clearly distinguish between particles of different sizes, with different thicknesses of metal coating, and different metallization schemes. The technique provides good repeatability and physical insight into the behavior of these particles that can guide adhesive design and the optimization of bonding processes.

  6. Measuring shape and size of micrometric particles from the analysis of the forward scattered field

    Science.gov (United States)

    Villa, S.; Sanvito, T.; Paroli, B.; Pullia, A.; Delmonte, B.; Potenza, M. A. C.

    2016-06-01

    Characterizing nano- and micro-particles in fluids still proves to be a significant challenge for both science and industry. Here, we show how to determine shape and size distributions of polydisperse water suspensions of micron-sized particles by the analysis of the field scattered in the forward direction by single particles illuminated by a laser beam. We exploit the novel Single Particle Extinction and Scattering method in connection with shear conditions which give preferred orientations to the particles passing through the scattering volume. Water suspensions of calibrated non-spherical particles, polydisperse standard monophasic mineral samples of quartz and kaolinite, and a mixture of quartz and illite are studied in detail. Application and limitation of the method are discussed.

  7. Single particle optical sizing; aggregation of polystyrene latices by salt and polymer.

    OpenAIRE

    Pelssers, E.G.M.

    1988-01-01

    The subject of this thesis is the development of a Single Particle Optical Sizer (SPOS) which is capable of measuring in detail discrete particle size distributions in the colloidal size range. With this instrument we studied the aggregation of latices induced by polymer and salt, and found evidence for non-equilibrium flocculation.Chapter 2 is an inventory of the existing methods of measuring aggregation. A comparison is made with our SPOS instrument. The techniques are classified into three...

  8. The influence of particle size on the chemistry of mica clays

    OpenAIRE

    Gassman, Paul Lawrence

    1990-01-01

    In order to assess the importance of particle size on elemental composition, structure, morphology, and charge characteristics of 2:1 micas, mechanically produced clay separates were analyzed by; electron probe microanalysis (EPMA), transmission electron microscopy (TEM), thermogravimetry, specific surface area analysis, and ion exchange. Books of biotite and muscovite were reduced to clay size « 2.0 μm) particles by mechanical comminution, then further fractionated into coar...

  9. Statistical estimation of stratospheric particle size distribution by combining optical modelling and lidar scattering measurements

    OpenAIRE

    J. Jumelet; S. Bekki; David, C.; P. Keckhut

    2008-01-01

    A method for estimating the stratospheric particle size distribution from multiwavelength lidar measurements is presented. It is based on matching measured and model-simulated backscatter coefficients. The lidar backscatter coefficients measured at the three commonly used wavelengths 355, 532 and 1064 nm are compared to a precomputed look-up table of model-calculated values. The optical model assumes that particles are spherical and that their size distribution is unimodal. ...

  10. Size-Segregated Particle Number Concentrations and Respiratory Emergency Room Visits in Beijing, China

    OpenAIRE

    Leitte, Arne Marian; Schlink, Uwe; Herbarth, Olf; Wiedensohler, Alfred; Pan, Xiao-Chuan; Hu, Min; Richter, Matthia; Wehner, Birgit; TUCH Thomas; Wu, Zhijun; Yang, Minjuan; Liu, Liqun; Breitner, Susanne; Cyrys, Josef; Peters, Annette

    2010-01-01

    Background The link between concentrations of particulate matter (PM) and respiratory morbidity has been investigated in numerous studies. Objectives The aim of this study was to analyze the role of different particle size fractions with respect to respiratory health in Beijing, China. Methods Data on particle size distributions from 3 nm to 1 μm; PM10 (PM ≤ 10 μm), nitrogen dioxide (NO2), and sulfur dioxide concentrations; and meteorologic variables were col