WorldWideScience

Sample records for sub-micron sized particles

  1. 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

  2. Sub-micron particle number size distribution characteristics at two urban locations in Leicester

    Science.gov (United States)

    Hama, Sarkawt M. L.; Cordell, Rebecca L.; Kos, Gerard P. A.; Weijers, E. P.; Monks, Paul S.

    2017-09-01

    The particle number size distribution (PNSD) of atmospheric particles not only provides information about sources and atmospheric processing of particles, but also plays an important role in determining regional lung dose. Owing to the importance of PNSD in understanding particulate pollution two short-term campaigns (March-June 2014) measurements of sub-micron PNSD were conducted at two urban background locations in Leicester, UK. At the first site, Leicester Automatic Urban Rural Network (AURN), the mean number concentrations of nucleation, Aitken, accumulation modes, the total particles, equivalent black carbon (eBC) mass concentrations were 2002, 3258, 1576, 6837 # cm-3, 1.7 μg m-3, respectively, and at the second site, Brookfield (BF), were 1455, 2407, 874, 4737 # cm-3, 0.77 μg m-3, respectively. The total particle number was dominated by the nucleation and Aitken modes, with both consisting of 77%, and 81% of total number concentrations at AURN and BF sites, respectively. This behaviour could be attributed to primary emissions (traffic) of ultrafine particles and the temporal evolution of mixing layer. The size distribution at the AURN site shows bimodal distribution at 22 nm with a minor peak at 70 nm. The size distribution at BF site, however, exhibits unimodal distribution at 35 nm. This study has for the first time investigated the effect of Easter holiday on PNSD in UK. The temporal variation of PNSD demonstrated a good degree of correlation with traffic-related pollutants (NOX, and eBC at both sites). The meteorological conditions, also had an impact on the PNSD and eBC at both sites. During the measurement period, the frequency of NPF events was calculated to be 13.3%, and 22.2% at AURN and BF sites, respectively. The average value of formation and growth rates of nucleation mode particles were 1.3, and 1.17 cm-3 s-1 and 7.42, and 5.3 nm h-1 at AURN, and BF sites, respectively. It can suggested that aerosol particles in Leicester originate mainly

  3. Dynamics of Dissolved Organic Matter and Microbes in Seawater through Sub-Micron Particle Size Analyses

    Digital Repository Service at National Institute of Oceanography (India)

    Goes, J.I.; Balch, W.M.; Vaughn, J.M.; Gomes, H.R.

    -78. Hansell, D.A. and Carlson, C.A., (1998) Deep-ocean gradients in the concentration of dissolved organic carbon. Nature, 395, 263-266. J. E. (1977) Characterization of suspended matter in the Gulf of Mexico ? II. Particles size analysis of suspended matter.... and Morris, I. (1980) Extracellular release of carbon by marine phytoplankton: a physiological approach. Limnol. Oceanogr., 25, 262-279. Maurer, L. G. (1976) Organic polymers in seawater: changes with depth in the Gulf of Mexico. Deep-Sea Res., 23, 1059...

  4. Short range investigation of sub-micron zirconia particles

    Energy Technology Data Exchange (ETDEWEB)

    Caracoche, M C; Martinez, J A [Departamento de Fisica, IFLP, Facultad de Ciencias Exactas, CICPBA, Universidad Nacional de La Plata (Argentina); Rivas, P C [IFLP-CONICET, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata (Argentina); Bondioli, F; Cannillo, V [Dipartimento di Ingegniria dei Materiali e dell' Ambiente, Facolta di Ingegneria, Universita di Modena e Reggio Emilia (Italy); Ferrari, A M, E-mail: cristina@fisica.unlp.edu.a [Dipartimento di Scienza a Metodi dell' Ingegneria, Universita di Modena e Reggio Emilia (Italy)

    2009-05-01

    The Perturbed Angular Correlations technique was used to determine the configurations around Zirconium ions and their thermal behavior in non-aggregated sub-micron zirconia spherical particles. Three residues containing- Zr surroundings were determined for the non-crystalline starting particles, which were identified under the assumption of a certain chemical reactions sequence during synthesis. While the one made up mainly by hydroxyl groups was common to both samples, the two involving mainly organic residues were particle size dependent. Upon crystallization, both samples stabilized in the t'- and t- tetragonal forms and the Xc-cubic form but their amounts and temperatures of appearance were different. On heating, the structure of the smaller particles became gradually monoclinic achieving total degradation upon the subsequent cooling to RT.

  5. Fabrication of magnetic and fluorescent chitin and dibutyrylchitin sub-micron particles by oil-in-water emulsification.

    Science.gov (United States)

    Blanco-Fernandez, Barbara; Chakravarty, Shatadru; Nkansah, Michael K; Shapiro, Erik M

    2016-11-01

    Chitin is a carbohydrate polymer with unique pharmacological and immunological properties, however, because of its unwieldy chemistry, the synthesis of discreet sized sub-micron particles has not been well reported. This work describes a facile and flexible method to fabricate biocompatible chitin and dibutyrylchitin sub-micron particles. This technique is based on an oil-in-water emulsification/evaporation method and involves the hydrophobization of chitin by the addition of labile butyryl groups onto chitin, disrupting intermolecular hydrogen bonds and enabling solubility in the organic solvent used as the oil phase during fabrication. The subsequent removal of butyryl groups post-fabrication through alkaline saponification regenerates native chitin while keeping particles morphology intact. Examples of encapsulation of hydrophobic dyes and nanocrystals are demonstrated, specifically using iron oxide nanocrystals and coumarin 6. The prepared particles had diameters between 300-400nm for dibutyrylchitin and 500-600nm for chitin and were highly cytocompatible. Moreover, they were able to encapsulate high amounts of iron oxide nanocrystals and were able to label mammalian cells. We describe a technique to prepare sub-micron particles of highly acetylated chitin (>90%) and dibutyrylchitin and demonstrate their utility as carriers for imaging. Chitin is a polysaccharide capable of stimulating the immune system, a property that depends on the acetamide groups, but its insolubility limits its use. No method for sub-micron particle preparation with highly acetylated chitins have been published. The only approach for the preparation of sub-micron particles uses low acetylation chitins. Dibutyrylchitin, a soluble chitin derivative, was used to prepare particles by oil in water emulsification. Butyryl groups were then removed, forming chitin particles. These particles could be suitable for encapsulation of hydrophobic payloads for drug delivery and cell imaging, as well as

  6. Practical Considerations for Detection and Characterization of Sub-Micron Particles in Protein Solutions by Nanoparticle Tracking Analysis.

    Science.gov (United States)

    Gruia, Flaviu; Parupudi, Arun; Polozova, Alla

    2015-01-01

    Nanoparticle Tracking Analysis (NTA) is an emerging analytical technique developed for detection, sizing, and counting of sub-micron particles in liquid media. Its feasibility for use in biopharmaceutical development was evaluated with particle standards and recombinant protein solutions. Measurements of aqueous suspensions of NIST-traceable polystyrene particle standards showed accurate particle concentration detection between 2 × 10(7) and 5 × 10(9) particles/mL. Sizing was accurate for particle standards up to 200 nm. Smaller than nominal value sizes were detected by NTA for the 300-900 nm particles. Measurements of protein solutions showed that NTA performance is solution-specific. Reduced sensitivity, especially in opalescent solutions, was observed. Measurements in such solutions may require sample dilution; however, common sample manipulations, such as dilution and filtration, may result in particle formation. Dilution and filtration case studies are presented to further illustrate such behavior. To benchmark general performance, NTA was compared against asymmetric flow field flow fractionation coupled with multi-angle light scattering (aF4-MALS) and dynamic light scattering, which are other techniques for sub-micron particles. Data shows that all three methods have limitations and may not work equally well under certain conditions. Nevertheless, the ability of NTA to directly detect and count sub-micron particles is a feature not matched by aF4-MALS or dynamic light scattering. Thorough characterization of particulate matter present in protein therapeutics is limited by the lack of analytical methods for particles in the sub-micron size range. Emerging techniques are being developed to bridge this analytical gap. In this study, Nanoparticle Tracking Analysis is evaluated as a potential tool for biologics development. Our results indicate that method performance is molecule-specific and may not work as well under all solution conditions, especially when

  7. Study of lead phytoavailability for atmospheric industrial micronic and sub-micronic particles in relation with lead speciation

    Energy Technology Data Exchange (ETDEWEB)

    Uzu, G. [EcoLab UMR 5245 CNRS-INPT-UPS, ENSAT BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan (France)], E-mail: gaelle.uzu@ensat.fr; Sobanska, S. [LASIR UMR 8516, Universite des Sciences et Technologies de Lille, Batiment C5, 59655 Villeneuve d' Ascq Cedex (France)], E-mail: Sophie.Sobanska@univ-lille1.fr; Aliouane, Y. [EcoLab UMR 5245 CNRS-INPT-UPS, ENSAT BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan (France); Pradere, P. [Chemical Metal Treatment Company, STCM, 30-32 chemin de Fondeyre, 31200 Toulouse (France)], E-mail: p.pradere@stc-metaux.com; Dumat, C. [EcoLab UMR 5245 CNRS-INPT-UPS, ENSAT BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan (France)], E-mail: camille.dumat@ensat.fr

    2009-04-15

    Particles from channelled emissions of a battery recycling facility were size-segregated and investigated to correlate their speciation and morphology with their transfer towards lettuce. Microculture experiments carried out with various calcareous soils spiked with micronic and sub-micronic particles (1650 {+-} 20 mg Pb kg{sup -1}) highlighted a greater transfer in soils mixed with the finest particles. According to XRD and Raman spectroscopy results, the two fractions presented differences in the amount of minor lead compounds like carbonates, but their speciation was quite similar, in decreasing order of abundance: PbS, PbSO{sub 4}, PbSO{sub 4}.PbO, {alpha}-PbO and Pb{sup 0}. Morphology investigations revealed that PM{sub 2.5} (i.e. Particulate Matter 2.5 composed of particles suspended in air with aerodynamic diameters of 2.5 {mu}m or less) contained many Pb nanoballs and nanocrystals which could influence lead availability. The soil-plant transfer of lead was mainly influenced by size and was very well estimated by 0.01 M CaCl{sub 2} extraction. - The soil-lettuce lead transfer from atmospheric industrial sub-micronic and micronic particles depends on particle size.

  8. Study of lead phytoavailability for atmospheric industrial micronic and sub-micronic particles in relation with lead speciation

    International Nuclear Information System (INIS)

    Uzu, G.; Sobanska, S.; Aliouane, Y.; Pradere, P.; Dumat, C.

    2009-01-01

    Particles from channelled emissions of a battery recycling facility were size-segregated and investigated to correlate their speciation and morphology with their transfer towards lettuce. Microculture experiments carried out with various calcareous soils spiked with micronic and sub-micronic particles (1650 ± 20 mg Pb kg -1 ) highlighted a greater transfer in soils mixed with the finest particles. According to XRD and Raman spectroscopy results, the two fractions presented differences in the amount of minor lead compounds like carbonates, but their speciation was quite similar, in decreasing order of abundance: PbS, PbSO 4 , PbSO 4 .PbO, α-PbO and Pb 0 . Morphology investigations revealed that PM 2.5 (i.e. Particulate Matter 2.5 composed of particles suspended in air with aerodynamic diameters of 2.5 μm or less) contained many Pb nanoballs and nanocrystals which could influence lead availability. The soil-plant transfer of lead was mainly influenced by size and was very well estimated by 0.01 M CaCl 2 extraction. - The soil-lettuce lead transfer from atmospheric industrial sub-micronic and micronic particles depends on particle size

  9. Kinetics of Sub-Micron Grain Size Refinement in 9310 Steel

    Science.gov (United States)

    Kozmel, Thomas; Chen, Edward Y.; Chen, Charlie C.; Tin, Sammy

    2014-05-01

    Recent efforts have focused on the development of novel manufacturing processes capable of producing microstructures dominated by sub-micron grains. For structural applications, grain refinement has been shown to enhance mechanical properties such as strength, fatigue resistance, and fracture toughness. Through control of the thermo-mechanical processing parameters, dynamic recrystallization mechanisms were used to produce microstructures consisting of sub-micron grains in 9310 steel. Starting with initial bainitic grain sizes of 40 to 50 μm, various levels of grain refinement were observed following hot deformation of 9310 steel samples at temperatures and strain rates ranging from 755 K to 922 K (482 °C and 649 °C) and 1 to 0.001/s, respectively. The resulting deformation microstructures were characterized using scanning electron microscopy and electron backscatter diffraction techniques to quantify the extent of carbide coarsening and grain refinement occurring during deformation. Microstructural models based on the Zener-Holloman parameter were developed and modified to include the effect of the ferrite/carbide interactions within the system. These models were shown to effectively correlate microstructural attributes to the thermal mechanical processing parameters.

  10. Sub-micron filter

    Science.gov (United States)

    Tepper, Frederick [Sanford, FL; Kaledin, Leonid [Port Orange, FL

    2009-10-13

    Aluminum hydroxide fibers approximately 2 nanometers in diameter and with surface areas ranging from 200 to 650 m.sup.2/g have been found to be highly electropositive. When dispersed in water they are able to attach to and retain electronegative particles. When combined into a composite filter with other fibers or particles they can filter bacteria and nano size particulates such as viruses and colloidal particles at high flux through the filter. Such filters can be used for purification and sterilization of water, biological, medical and pharmaceutical fluids, and as a collector/concentrator for detection and assay of microbes and viruses. The alumina fibers are also capable of filtering sub-micron inorganic and metallic particles to produce ultra pure water. The fibers are suitable as a substrate for growth of cells. Macromolecules such as proteins may be separated from each other based on their electronegative charges.

  11. Water ice and sub-micron ice particles on Tethys and Mimas

    Science.gov (United States)

    Scipioni, Francesca; Nordheim, Tom; Clark, Roger Nelson; D'Aversa, Emiliano; Cruikshank, Dale P.; Tosi, Federico; Schenk, Paul M.; Combe, Jean-Philippe; Dalle Ore, Cristina M.

    2017-10-01

    IntroductionWe present our ongoing work, mapping the variation of the main water ice absorption bands, and the distribution of the sub-micron particles, across Mimas and Tethys’ surfaces using Cassini-VIMS cubes acquired in the IR range (0.8-5.1 μm). We present our results in the form of maps of variation of selected spectral indicators (depth of absorption bands, reflectance peak height, spectral slopes).Data analysisVIMS acquires hyperspectral data in the 0.3-5.1 μm spectral range. We selected VIMS cubes of Tethys and Mimas in the IR range (0.8-5.1 μm). For all pixels in the selected cubes, we measured the band depths for water-ice absorptions at 1.25, 1.5 and 2.02 μm and the height of the 3.6 μm reflection peak. Moreover, we considered the spectral indictors for particles smaller than 1 µm [1]: (i) the 2 µm absorption band is asymmetric and (ii) it has the minimum shifted to longer λ (iii) the band depth ratio 1.5/2.0 µm decreases; (iv) the reflection peak at 2.6 µm decreases; (v) the Fresnel reflection peak is suppressed; (vi) the 5 µm reflectance is decreased relative to the 3.6 µm peak. To characterize the global variation of water-ice band depths, and of sub-micron particles spectral indicators, across Mimas and Tethys, we sampled the two satellites’ surfacees with a 1°x1° fixed-resolution grid and then averaged the band depths and peak values inside each square cell.3. ResultsFor both moons we find that large geologic features, such as the Odysseus and Herschel impact basins, do not correlate with water ice’s abundance variation. For Tethys, we found a quite uniform surface on both hemispheres. The only deviation from this pattern shows up on the trailing hemisphere, where we notice two north-oriented, dark areas around 225° and 315°. For Mimas, the leading and trailing hemispheres appear to be quite similar in water ice abundance, the trailing portion having water ice absorption bands lightly more suppressed than the leading side

  12. EXPLORING THE ROLE OF SUB-MICRON-SIZED DUST GRAINS IN THE ATMOSPHERES OF RED L0–L6 DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Hiranaka, Kay; Cruz, Kelle L.; Baldassare, Vivienne F. [Hunter College, Department of Physics and Astronomy, City University of New York, 695 Park Ave, New York, NY 10065 (United States); Douglas, Stephanie T. [American Museum of Natural History, Department of Astrophysics, Central Park West at 79th Street, New York, NY 10024 (United States); Marley, Mark S., E-mail: khiranak@hunter.cuny.edu [NASA Ames Research Center, MS-245-3, Moffett Field, CA 94035 (United States)

    2016-10-20

    We examine the hypothesis that the red near-infrared colors of some L dwarfs could be explained by a “dust haze” of small particles in their upper atmospheres. This dust haze would exist in conjunction with the clouds found in dwarfs with more typical colors. We developed a model that uses Mie theory and the Hansen particle size distributions to reproduce the extinction due to the proposed dust haze. We apply our method to 23 young L dwarfs and 23 red field L dwarfs. We constrain the properties of the dust haze including particle size distribution and column density using Markov Chain Monte Carlo methods. We find that sub-micron-range silicate grains reproduce the observed reddening. Current brown dwarf atmosphere models include large-grain (1–100 μ m) dust clouds but not sub-micron dust grains. Our results provide a strong proof of concept and motivate a combination of large and small dust grains in brown dwarf atmosphere models.

  13. Characterisation of sub-micron particle number concentrations and formation events in the western Bushveld Igneous Complex, South Africa

    Directory of Open Access Journals (Sweden)

    A. Hirsikko

    2012-05-01

    Full Text Available South Africa holds significant mineral resources, with a substantial fraction of these reserves occurring and being processed in a large geological structure termed the Bushveld Igneous Complex (BIC. The area is also highly populated by informal, semi-formal and formal residential developments. However, knowledge of air quality and research related to the atmosphere is still very limited in the area. In order to investigate the characteristics and processes affecting sub-micron particle number concentrations and formation events, air ion and aerosol particle size distributions and number concentrations, together with meteorological parameters, trace gases and particulate matter (PM were measured for over two years at Marikana in the heart of the western BIC. The observations showed that trace gas (i.e. SO2, NOx, CO and black carbon concentrations were relatively high, but in general within the limits of local air quality standards. The area was characterised by very high condensation sink due to background aerosol particles, PM10 and O3 concentration. The results indicated that high amounts of Aitken and accumulation mode particles originated from domestic burning for heating and cooking in the morning and evening, while during daytime SO2-based nucleation followed by the growth by condensation of vapours from industrial, residential and natural sources was the most probable source for large number concentrations of nucleation and Aitken mode particles. Nucleation event day frequency was extremely high, i.e. 86% of the analysed days, which to the knowledge of the authors is the highest frequency ever reported. The air mass back trajectory and wind direction analyses showed that the secondary particle formation was influenced both by local and regional pollution and vapour sources. Therefore, our observation of the annual cycle and magnitude of the particle formation and growth rates during

  14. IBA and synchrotron methods for sub-micron fine particle characterisation

    International Nuclear Information System (INIS)

    Cohen, D.D.; Siegele, R. Stampfl. A.; Cai, Z.; Ilinski, P.; Rodrigues, W.; Legnini, D.G.; Yun, W.; Lai, B.

    1999-01-01

    Fine air-borne particles, whose average diameters are 2.5 μm and less (PM2.5), are known to play significant roles in a number of human and environmental issues. They may penetrate deep into the human lung system and are believed, due to their small size or due to toxins adsorbed onto their surfaces, to be responsible for up to 60,000 and 10,000 deaths in the U.S. and U.K. respectively. Health studies within NSW, Australia carried out by the NSW EPA, have shown increased hospital admissions and excess deaths related to high fine particle pollution episodes. A number of environmental issues are affected by the amount and type of fine-particles in the air. The white and brown hazes that occur in populated cities causing poor visibility are due to light scattering from fine particles. These same particles are easily transported large distances in the lower atmosphere playing a key role in global pollution and climate forcing. Current knowledge of fine-particle concentrations and constituents is very limited. Sources of fine particles are both natural and man-made. Over the past few years considerable work on the characterisation of these particles has been going on at ANSTO using accelerator based ion beam analysis (IBA) methods. X-ray fluorescence using ion beams from accelerators and synchrotron fluorescence are complementary techniques. This is well demonstrated by the plot. PIXE has higher cross sections for low Z elements, but for high Z elements closer to the excitation energy (16keV) synchrotron radiation cross sections are larger. Both techniques are multi-elemental analysis techniques

  15. Thermal and mechanical behaviour of sub micron sized fly ash reinforced polyester resin composite

    Science.gov (United States)

    Nantha Kumar, P.; Rajadurai, A.; Muthuramalingam, T.

    2018-04-01

    The utilization of particles reinforced resin matrix composites is being increased owing to its lower density and high strength to weight ratio. In the present study, an attempt has been made to synthesize fly ash particles reinforced polyester resin composite for engine cowling application. The thermal stability and mechanical behaviours such as hardness and flexural strength of the composite with 2, 3 and 4 weight % of reinforcement is studied and analyzed. The thermo gravimetric analysis indicates that the higher addition of reinforcement increases the decomposition temperature due to its refractory nature. It is also observed that the hardness increases with higher filler addition owing to the resistance of FA particles towards penetration. The flexural strength is found to increase up to the addition of 3% of FA particles, whereas the polyester resin composite prepared with 4% FA particles addition is observed to have low flexural strength owing to agglomeration of particles.

  16. Synthesis and characterization of monodisperse, mesoporous, and magnetic sub-micron particles doped with a near-infrared fluorescent dye

    International Nuclear Information System (INIS)

    Le Guevel, Xavier; Nooney, Robert; McDonagh, Colette; MacCraith, Brian D.

    2011-01-01

    Recently, multifunctional silica nanoparticles have been investigated extensively for their potential use in biomedical applications. We have prepared sub-micron monodisperse and stable multifunctional mesoporous silica particles with a high level of magnetization and fluorescence in the near infrared region using an one-pot synthesis technique. Commercial magnetite nanocrystals and a conjugated-NIR-dye were incorporated inside the particles during the silica condensation reaction. The particles were then coated with polyethyleneglycol to stop aggregation. X-ray diffraction, N 2 adsorption analysis, TEM, fluorescence and absorbance measurements were used to structurally characterize the particles. These mesoporous silica spheres have a large surface area (1978 m 2 /g) with 3.40 nm pore diameter and a high fluorescence in the near infrared region at λ=700 nm. To explore the potential of these particles for drug delivery applications, the pore accessibility to hydrophobic drugs was simulated by successfully trapping a hydrophobic ruthenium dye complex inside the particle with an estimated concentration of 3 wt%. Fluorescence imaging confirmed the presence of both NIR dye and the post-grafted ruthenium dye complex inside the particles. These particles moved at approximately 150 μm/s under the influence of a magnetic field, hence demonstrating the multifunctionality and potential for biomedical applications in targeting and imaging. - Graphical Abstract: Hydrophobic fluorescent Ruthenium complex has been loaded into the mesopores as a surrogate drug to simulate drug delivery and to enhance the multifunctionality of the magnetic NIR emitting particles. Highlights: → Monodisperse magnetic mesoporous silica particles emitting in the near infrared region are obtained in one-pot synthesis. → We prove the capacity of such particles to uptake hydrophobic dye to mimic drug loading. → Loaded fluorescent particles can be moved under a magnetic field in a microfluidic

  17. Assessment of Sub-Micron Particles by Exploiting Charge Differences with Dielectrophoresis

    Directory of Open Access Journals (Sweden)

    Maria F. Romero-Creel

    2017-08-01

    Full Text Available The analysis, separation, and enrichment of submicron particles are critical steps in many applications, ranging from bio-sensing to disease diagnostics. Microfluidic electrokinetic techniques, such as dielectrophoresis (DEP have proved to be excellent platforms for assessment of submicron particles. DEP is the motion of polarizable particles under the presence of a non-uniform electric field. In this work, the polarization and dielectrophoretic behavior of polystyrene particles with diameters ranging for 100 nm to 1 μm were studied employing microchannels for insulator based DEP (iDEP and low frequency (<1000 Hz AC and DC electric potentials. In particular, the effects of particle surface charge, in terms of magnitude and type of functionalization, were examined. It was found that the magnitude of particle surface charge has a significant impact on the polarization and dielectrophoretic response of the particles, allowing for successful particle assessment. Traditionally, charge differences are exploited employing electrophoretic techniques and particle separation is achieved by differential migration. The present study demonstrates that differences in the particle’s surface charge can also be exploited by means of iDEP; and that distinct types of nanoparticles can be identified by their polarization and dielectrophoretic behavior. These findings open the possibility for iDEP to be employed as a technique for the analysis of submicron biological particles, where subtle differences in surface charge could allow for rapid particle identification and separation.

  18. Design and characterization of radiation resistant integrated circuits for the LHC particle detectors using deep sub-micron CMOS technologies

    International Nuclear Information System (INIS)

    Anelli, Giovanni Maria

    2000-01-01

    The electronic circuits associated with the particle detectors of the CERN Large Hadron Collider (LHC) have to work in a highly radioactive environment. This work proposes a methodology allowing the design of radiation resistant integrated circuits using the commercial sub-micron CMOS technology. This method uses the intrinsic radiation resistance of ultra-thin grid oxides, the technology of enclosed layout transistors (ELT), and the protection rings to avoid the radio-induced creation of leakage currents. In order to check the radiation tolerance level, several test structures have been designed and tested with different radiation sources. These tests have permitted to study the physical phenomena responsible for the damages induced by the radiations and the possible remedies. Then, the particular characteristics of ELT transistors and their influence on the design of complex integrated circuits has been explored. The modeling of the W/L ratio, the asymmetries (for instance in the output conductance) and the performance of ELT couplings have never been studied yet. The noise performance of the 0.25 μ CMOS technology, used in the design of several integrated circuits of the LHC detectors, has been characterized before and after irradiation. Finally, two integrated circuits designed using the proposed method are presented. The first one is an analogic memory and the other is a circuit used for the reading of the signals of one of the LHC detectors. Both circuits were irradiated and have endured very high doses practically without any sign of performance degradation. (J.S.)

  19. On the sub-micron aerosol size distribution in a coastal-rural site at El Arenosillo Station (SW – Spain

    Directory of Open Access Journals (Sweden)

    M. Sorribas

    2011-11-01

    Full Text Available This study focuses on the analysis of the sub-micron aerosol characteristics at El Arenosillo Station, a rural and coastal environment in South-western Spain between 1 August 2004 and 31 July 2006 (594 days. The mean total concentration (NT was 8660 cm−3 and the mean concentrations in the nucleation (NNUC, Aitken (NAIT and accumulation (NACC particle size ranges were 2830 cm−3, 4110 cm−3 and 1720 cm−3, respectively. Median size distribution was characterised by a single-modal fit, with a geometric diameter, median number concentration and geometric standard deviation of 60 nm, 5390 cm−3 and 2.31, respectively. Characterisation of primary emissions, secondary particle formation, changes to meteorology and long-term transport has been necessary to understand the seasonal and annual variability of the total and modal particle concentration. Number concentrations exhibited a diurnal pattern with maximum concentrations around noon. This was governed by the concentrations of the nucleation and Aitken modes during the warm seasons and only by the nucleation mode during the cold seasons. Similar monthly mean total concentrations were observed throughout the year due to a clear inverse variation between the monthly mean NNUC and NACC. It was related to the impact of desert dust and continental air masses on the monthly mean particle levels. These air masses were associated with high values of NACC which suppressed the new particle formation (decreasing NNUC. Each day was classified according to a land breeze flow or a synoptic pattern influence. The median size distribution for desert dust and continental aerosol was dominated by the Aitken and accumulation modes, and marine air masses were dominated by the nucleation and Aitken modes. Particles

  20. The inhalation of insoluble iron oxide particles in the sub-micron ranges. Part II - Plutonium-237 labelled aerosols

    International Nuclear Information System (INIS)

    Waite, D.A.; Ramsden, D.

    1971-10-01

    The results of a series of inhalation studies using iron oxide particles in the size range 0.1 to 0.3 um (count median diameter) are described. In this series the aerosols were labelled with plutonium 237. In vivo detection, excretion analysis and crude location studies were obtainable and the results compared to the earlier studies using chromium 51 labelled aerosols. Plutonium 237 can be considered as a simulator for plutonium 239 and attempts are made to extrapolate the results to the problem of the estimation of plutonium 239 in the human lung. (author)

  1. Small Sub-micron-Particle Position-Resolving Laser-Doppler Velocimeter for High-Speed Flows, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objectives of this proposed work are to develop and prove the use of LDV and CompLDV for particle-position-resolving and flow velocity profile...

  2. Comparative Mineralogy, Microstructure and Compositional Trends in the Sub-Micron Size Fractions of Mare and Highland Lunar Soils

    Science.gov (United States)

    Thompson, M. S.; Christoffersen, R.; Noble, S. K.; Keller, L. P.

    2012-01-01

    The morphology, mineralogy, chemical composition and optical properties of lunar soils show distinct correlations as a function of grain size and origin [1,2,3]. In the fraction, there is an increased correlation between lunar surface properties observed through remote sensing techniques and those attributed to space weathering phenomenae [1,2]. Despite the establishment of recognizable trends in lunar grains fraction fraction for both highland and mare derived soils. The properties of these materials provide the focus for many aspects of lunar research including the nature of space weathering on surface properties, electrostatic grain transport [4,5] and dusty plasmas [5]. In this study, we have used analytical transmission and scanning transmission electron microscopy (S/TEM) to characterize the mineralogy type, microstructure and major element compositions of grains in this important size range in lunar soils.

  3. Portable sample preparation and analysis system for micron and sub-micron particle characterization using light scattering and absorption spectroscopy

    Science.gov (United States)

    Stark, Peter C [Los Alamos, NM; Zurek, Eduardo [Barranquilla, CO; Wheat, Jeffrey V [Fort Walton Beach, FL; Dunbar, John M [Santa Fe, NM; Olivares, Jose A [Los Alamos, NM; Garcia-Rubio, Luis H [Temple Terrace, FL; Ward, Michael D [Los Alamos, NM

    2011-07-26

    There is provided a method and device for remote sampling, preparation and optical interrogation of a sample using light scattering and light absorption methods. The portable device is a filtration-based device that removes interfering background particle material from the sample matrix by segregating or filtering the chosen analyte from the sample solution or matrix while allowing the interfering background particles to be pumped out of the device. The segregated analyte is then suspended in a diluent for analysis. The device is capable of calculating an initial concentration of the analyte, as well as diluting the analyte such that reliable optical measurements can be made. Suitable analytes include cells, microorganisms, bioparticles, pathogens and diseases. Sample matrixes include biological fluids such as blood and urine, as well as environmental samples including waste water.

  4. Influence of biomass burning on mixing state of sub-micron aerosol particles in the North China Plain

    Science.gov (United States)

    Kecorius, Simonas; Ma, Nan; Teich, Monique; van Pinxteren, Dominik; Zhang, Shenglan; Gröβ, Johannes; Spindler, Gerald; Müller, Konrad; Iinuma, Yoshiteru; Hu, Min; Herrmann, Hartmut; Wiedensohler, Alfred

    2017-09-01

    Particulate emissions from crop residue burning decrease the air quality as well as influence aerosol radiative properties on a regional scale. The North China Plain (NCP) is known for the large scale biomass burning (BB) of field residues, which often results in heavy haze pollution episodes across the region. We have been able to capture a unique BB episode during the international CAREBeijing-NCP intensive field campaign in Wangdu in the NCP (38.6°N, 115.2°E) from June to July 2014. It was found that aerosol particles originating from this BB event showed a significantly different mixing state compared with clean and non-BB pollution episodes. BB originated particles showed a narrower probability density function (PDF) of shrink factor (SF). And the maximum was found at shrink factor of 0.6, which is higher than in other episodes. The non-volatile particle number fraction during the BB episode decreased to 3% and was the lowest measured value compared to all other predefined episodes. To evaluate the influence of particle mixing state on aerosol single scattering albedo (SSA), SSA at different RHs was simulated using the measured aerosol physical-chemical properties. The differences between the calculated SSA for biomass burning, clean and pollution episodes are significant, meaning that the variation of SSA in different pollution conditions needs to be considered in the evaluation of aerosol direct radiative effects in the NCP. And the calculated SSA was found to be quite sensitive on the mixing state of BC, especially at low-RH condition. The simulated SSA was also compared with the measured values. For all the three predefined episodes, the measured SSA are very close to the calculated ones with assumed mixing states of homogeneously internal and core-shell internal mixing, indicating that both of the conception models are appropriate for the calculation of ambient SSA in the NCP.

  5. Continuous and simultaneous measurement of the tank-treading motion of red blood cells and the surrounding flow using translational confocal micro-particle image velocimetry (micro-PIV) with sub-micron resolution

    International Nuclear Information System (INIS)

    Oishi, M; Utsubo, K; Kinoshita, H; Fujii, T; Oshima, M

    2012-01-01

    In this study, a translational confocal micro-particle image velocimetry (PIV) system is introduced to measure the microscopic interaction between red blood cells (RBCs) and the surrounding flow. Since the macroscopic behavior of RBCs, such as the tank-treading motion, is closely related to the axial migration and other flow characteristics in arterioles, the measurement method must answer the conflicting demands of sub-micron resolution, continuous measurement and applicability for high-speed flow. In order to avoid loss of the measurement target, i.e. RBCs, from the narrow field of view during high-magnification measurement, the translation stage with the flow device moves in the direction opposite the direction of flow. The proposed system achieves the measurement of higher absolute velocities compared with a conventional confocal micro-PIV system without the drawbacks derived from stage vibration. In addition, we have applied a multicolor separation unit, which can measure different phases simultaneously using different fluorescent particles, in order to clarify the interaction between RBCs and the surrounding flow. Based on our measurements, the tank-treading motion of RBCs depends on the shear stress gradient of the surrounding flow. Although, the relationship between the tank-treading frequency and the shear rate of the surrounding flow is of the same order as in the previous uniform shear rate experiments, our results reveal the remarkable behavior of the non-uniform membrane velocities and lateral velocity component of flow around the RBCs. (paper)

  6. Scanning SQUID susceptometers with sub-micron spatial resolution

    International Nuclear Information System (INIS)

    Kirtley, John R.; Rosenberg, Aaron J.; Palmstrom, Johanna C.; Holland, Connor M.; Moler, Kathryn A.; Paulius, Lisa; Spanton, Eric M.; Schiessl, Daniel; Jermain, Colin L.; Gibbons, Jonathan; Fung, Y.-K.K.; Gibson, Gerald W.; Huber, Martin E.; Ralph, Daniel C.; Ketchen, Mark B.

    2016-01-01

    Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ_0/Hz"1"/"2. This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes the spacing between the sample surface and the SQUID pickup loop. We describe the design, modeling, fabrication, and testing of these sensors. Although sub-micron spatial resolution has been achieved previously in scanning SQUID sensors, our sensors not only achieve high spatial resolution but also have integrated modulation coils for flux feedback, integrated field coils for susceptibility measurements, and batch processing. They are therefore a generally applicable tool for imaging sample magnetization, currents, and susceptibilities with higher spatial resolution than previous susceptometers.

  7. Scanning SQUID susceptometers with sub-micron spatial resolution

    Energy Technology Data Exchange (ETDEWEB)

    Kirtley, John R., E-mail: jkirtley@stanford.edu; Rosenberg, Aaron J.; Palmstrom, Johanna C.; Holland, Connor M.; Moler, Kathryn A. [Department of Applied Physics, Stanford University, Stanford, California 94305-4045 (United States); Paulius, Lisa [Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008-5252 (United States); Spanton, Eric M. [Department of Physics, Stanford University, Stanford, California 94305-4045 (United States); Schiessl, Daniel [Attocube Systems AG, Königinstraße 11A, 80539 Munich (Germany); Jermain, Colin L.; Gibbons, Jonathan [Department of Physics, Cornell University, Cornell, Ithaca, New York 14853 (United States); Fung, Y.-K.K.; Gibson, Gerald W. [IBM Research Division, T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Huber, Martin E. [Department of Physics, University of Colorado Denver, Denver, Colorado 80217-3364 (United States); Ralph, Daniel C. [Department of Physics, Cornell University, Cornell, Ithaca, New York 14853 (United States); Kavli Institute at Cornell, Ithaca, New York 14853 (United States); Ketchen, Mark B. [OcteVue, Hadley, Massachusetts 01035 (United States)

    2016-09-15

    Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ{sub 0}/Hz{sup 1/2}. This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes the spacing between the sample surface and the SQUID pickup loop. We describe the design, modeling, fabrication, and testing of these sensors. Although sub-micron spatial resolution has been achieved previously in scanning SQUID sensors, our sensors not only achieve high spatial resolution but also have integrated modulation coils for flux feedback, integrated field coils for susceptibility measurements, and batch processing. They are therefore a generally applicable tool for imaging sample magnetization, currents, and susceptibilities with higher spatial resolution than previous susceptometers.

  8. Toxic assessment of urban atmospheric particle-bound PAHs: Relevance of composition and particle size in Barcelona (Spain)

    International Nuclear Information System (INIS)

    Mesquita, Sofia Raquel; Drooge, Barend L. van; Reche, Cristina; Guimarães, Laura; Grimalt, Joan O.; Barata, Carlos; Piña, Benjamin

    2014-01-01

    Zebrafish embryotoxicity and dioxin-like activity levels were tested for particulate air samples from an urban background site in Barcelona (Spain). Samples were collected during 14 months, and maximal values for both biological activities corresponded to samples collected during late autumn months, correlating with elevated PAH levels. Vehicle and combustion emissions appeared as the potentially most toxic sources, whereas total PM mass and mineral content appeared to be poor predictors of the biological activity of the samples. Samples simultaneously collected at different particle size cut-offs (10, 2.5, and 1 μm) did not differ significantly in dioxin-like PAH levels and biological activity, indicating that the sub-micron particle fraction (PM 1 ) concentrated essentially all observed toxicity. Our results support the need for a tighter control on sub-micron particle emissions and show that total PM mass and, particularly, PM 10 , may not fully characterize the toxic potential of air samples. Highlights: • Dioxin-like activity was found in all air particle samples collected in Barcelona. • 50% of the samples showed different levels of fish embryotoxicity. • Toxic effects associated to PAHs and linked to vehicle and combustion emissions. • The toxicity was not correlated to PM mass or mineral content. • The sub-micron particle fraction PM 1 concentrated essentially all observed toxicity. -- In vivo toxic effects associated to sub-micron urban air particles from combustion and vehicle emissions

  9. Lung deposition of sub-micron aerosols calculated as a function of age and breathing rate

    International Nuclear Information System (INIS)

    James, A.C.

    1978-01-01

    Experimental measurements of lung deposition and especially of regional deposition, of aerosols in the sub-micron size range have been so few that it is worthwhile establishing a method of calculation. A computer routine has therefore been developed to calculate aerosol deposition in successive bronchial and bronchiolar generations of the Weibel 'A' model of human lung for the sub-micron size range where deposition occurs solely by diffusion. This model can be scaled to represent lungs at various ages and vital capacities. Some calculated results are presented here and compared with measurements of lung deposition made under carefully controlled conditions in humans. (author)

  10. Fabrication, microstructure, and mechanical properties of high strength cobalt sub-micron structures

    International Nuclear Information System (INIS)

    Jin Sumin; Burek, Michael J.; Evans, Robert D.; Jahed, Zeinab; Leung, Michael C.; Evans, Neal D.; Tsui, Ting Y.

    2012-01-01

    The mechanical properties exhibited by sub-micron scale columnar structures of cobalt, fabricated by electron beam lithography and electroplating techniques, were investigated through uniaxial compression. Transmission electron microscopy analyses show these specimens possess a microstructure with sub-micron grains which are elongated and aligned near to the pillar loading axis. In addition, small nanocrystalline cobalt crystals are also present within the columnar structure. These specimens display exceptional mechanical strength comparable with both bulk polycrystalline and nanocrystalline cobalt deposited by electroplating. Size-dependent softening with shrinking sample dimensions is also observed in this work. Additionally, the strength of these sub-micron structures appears to be strain rate sensitive and comparable with bulk nanocrystalline cobalt specimens.

  11. Block copolymer stabilized nonaqueous biocompatible sub-micron emulsions for topical applications.

    Science.gov (United States)

    Atanase, Leonard Ionut; Riess, Gérard

    2013-05-20

    Polyethylene glycol (PEG) 400/Miglyol 812 non-aqueous sub-micron emulsions were developed due to the fact that they are of interest for the design of drug-loaded biocompatible topical formulations. These types of emulsions were favourably stabilized by poly (2-vinylpyridine)-b-poly (butadiene) (P2VP-b-PBut) copolymer with DPBut>DP2VP, each of these sequences being well-adapted to the solubility parameters of PEG 400 and Miglyol 812, respectively. This type of block copolymers, which might limit the Ostwald ripening, appeared to be more efficient stabilizers than low molecular weight non-ionic surfactants. The emulsion characteristics, such as particle size, stability and viscosity at different shear rates were determined as a function of the phase ratio, the copolymer concentration and storage time. It was further shown that Acyclovir, as a model drug of low water solubility, could be incorporated into the PEG 400 dispersed phase, with no significant modification of the initial emulsion characteristics. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Particle size determination

    International Nuclear Information System (INIS)

    Burr, K.J.

    1979-01-01

    A specification is given for an apparatus to provide a completely automatic testing cycle to determine the proportion of particles of less than a predetermined size in one of a number of fluid suspensions. Monitoring of the particle concentration during part of the process can be carried out by an x-ray source and detector. (U.K.)

  13. The Columbia University Sub-micron Charged Particle Beam

    Science.gov (United States)

    Randers-Pehrson, Gerhard; Johnson, Gary W.; Marino, Stephen A.; Xu, Yanping; Dymnikov, Alexander D.; Brenner, David J.

    2009-01-01

    A lens system consisting of two electrostatic quadrupole triplets has been designed and constructed at the Radiological Research Accelerator Facility (RARAF) of Columbia University. The lens system has been used to focus 6-MeV 4He ions to a beam spot in air with a diameter of 0.8 µm. The quadrupole electrodes can withstand voltages high enough to focus 4He ions up to 10 MeV and protons up to 5 MeV. The quadrupole triplet design is novel in that alignment is made through precise construction and the relative strengths of the quadrupoles are accomplished by the lengths of the elements, so that the magnitudes of the voltages required for focusing are nearly identical. The insulating sections between electrodes have had ion implantation to improve the voltage stability of the lens. The lens design employs Russian symmetry for the quadrupole elements. PMID:20161365

  14. The Columbia University sub-micron charged particle beam

    International Nuclear Information System (INIS)

    Randers-Pehrson, Gerhard; Johnson, Gary W.; Marino, Stephen A.; Xu Yanping; Dymnikov, Alexander D.; Brenner, David J.

    2009-01-01

    A lens system consisting of two electrostatic quadrupole triplets has been designed and constructed at the Radiological Research Accelerator Facility (RARAF) of Columbia University. The lens system has been used to focus 6 MeV 4 He ions to a beam spot in air with a diameter of 0.8 μm. The quadrupole electrodes can withstand voltages high enough to focus 4 He ions up to 10 MeV and protons up to 5 MeV. The quadrupole triplet design is novel in that alignment is made through precise construction and the relative strengths of the quadrupoles are accomplished by the lengths of the elements, so that the magnitudes of the voltages required for focusing are nearly identical. The insulating sections between electrodes have had ion implantation to improve the voltage stability of the lens. The lens design employs Russian symmetry for the quadrupole elements.

  15. Synthesis and characterization of hollow α-Fe2O3 sub-micron spheres prepared by sol–gel

    International Nuclear Information System (INIS)

    León, Lizbet; Bustamante, Angel; Osorio, Ana; Olarte, G. S.; Santos Valladares, Luis De Los; Barnes, Crispin H. W.; Majima, Yutaka

    2011-01-01

    In this work we report the preparation of magnetic hematite hollow sub-micron spheres (α-Fe 2 O 3 ) by colloidal suspensions of ferric nitrate nine-hydrate (Fe(NO 3 ) 3 ·9H 2 O) particles in citric acid solution by following the sol–gel method. After the gel formation, the samples were annealed at different temperatures in an oxidizing atmosphere. Annealing at 180°C resulted in an amorphous phase, without iron oxide formation. Annealing at 250°C resulted in coexisting phases of hematite, maghemite and magnetite, whereas at 400°C, only hematite and maghemite were found. Pure hematite hollow sub-micron spheres with porous shells were formed after annealing at 600°C. The characterization was performed by X-ray diffraction (XRD), Mössbauer spectroscopy (MS) and scanning electron microscopy (SEM).

  16. Impact-disrupted gunshot residue: A sub-micron analysis using a novel collection protocol

    Directory of Open Access Journals (Sweden)

    V. Spathis

    2017-06-01

    Full Text Available The analysis of gunshot residue (GSR has played an integral role within the legal system in relation to shooting cases. With a characteristic elemental composition of lead, antimony, barium, and a typically discriminative spheroidal morphology, the presence and distribution of GSR can aid in firearm investigations. In this experiment, three shots of low velocity rim-fire ammunition were fired over polished silicon collection substrates placed at six intervals over a 100 cm range. The samples were analysed using a Field Emission Gun Scanning Electron Microscope (FEG-SEM in conjunction with an X-flash Energy Dispersive X-ray (EDX detector, allowing for GSR particle analyses of composition and structure at the sub-micron level. The results of this experiment indicate that although classic spheroidal particles are present consistently throughout the entire range of samples their sizes vary significantly, and at certain distances from the firearm particles with an irregular morphology were discerned, forming “impact-disrupted” GSR particles, henceforth colloquially referred to as “splats”. Upon further analysis, trends with regards to the formation of these splat particles were distinguished. An increase in splat frequency was observed starting at 10 cm from the firearm, with 147 mm−2 splat density, reaching a maximal flux at 40 cm (451 mm−2, followed by a gradual decrease to the maximum range sampled. Moreover, the structural morphology of the splats changes throughout the sampling range. At the distances closest to the firearm, molten-looking particles were formed, demonstrating the metallic residues were in a liquid state when their flight path was disrupted. However, at increased distances-primarily where the discharge plume was at maximum dispersion and moving away from the firearm, the residues have had time to cool in-fight resulting in semi-congealed and solid particles that subsequently disrupted upon impact, forming more

  17. Characterization of in-situ annealed sub-micron thick Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Byoung-Soo; Sung, Shi-Joon; Hwang, Dae-Kue, E-mail: dkhwang@dgist.ac.kr

    2015-09-01

    Sub-micron thick Cu(In,Ga)Se{sub 2} (CIGS) thin films were deposited on Mo-coated soda-lime glass substrates under various conditions by single-stage co-evaporation. Generally, the short circuit current (J{sub sc}) decreased with the decreasing thickness of the absorber layer. However, in this study, J{sub sc} was nearly unchanged with decreasing thickness, while the open circuit voltage (V{sub oc}) and fill factor (FF) decreased by 31.9 and 31.1%, respectively. We believe that the remarkable change of V{sub oc} and FF can be attributed to the difference in the total amount of injected thermal energy. Using scanning electron microscopy, we confirmed that the surface morphology becomes smooth and the grain size increased after the annealing process. In the X-ray diffraction patterns, the CIGS thin film also showed an improved crystal quality. We observed that the electric properties were improved by the in-situ annealing of CIGS thin films. The reverse saturation current density of the annealed CIGS solar cell was 100 times smaller than that of reference solar cell. Thus, sub-micron CIGS thin films annealed under a constant Se rate showed a 64.7% improvement in efficiency. - Highlights: • The effects of in-situ annealing the sub-micron CIGS film have been investigated. • The surface morphology and the grain size were improved by in-situ annealing. • The V{sub oc} and FF of the films were increased by about 30% after in-situ annealing. • In-situ annealing of sub-micron thick CIGS films can be improved an efficiency.

  18. Imaging of vaporised sub-micron phase change contrast agents with high frame rate ultrasound and optics

    Science.gov (United States)

    Lin, Shengtao; Zhang, Ge; Jamburidze, Akaki; Chee, Melisse; Hau Leow, Chee; Garbin, Valeria; Tang, Meng-Xing

    2018-03-01

    Phase-change ultrasound contrast agent (PCCA), or nanodroplet, shows promise as an alternative to the conventional microbubble agent over a wide range of diagnostic applications. Meanwhile, high-frame-rate (HFR) ultrasound imaging with microbubbles enables unprecedented temporal resolution compared to traditional contrast-enhanced ultrasound imaging. The combination of HFR ultrasound imaging and PCCAs can offer the opportunity to observe and better understand PCCA behaviour after vaporisation captures the fast phenomenon at a high temporal resolution. In this study, we utilised HFR ultrasound at frame rates in the kilohertz range (5-20 kHz) to image native and size-selected PCCA populations immediately after vaporisation in vitro within clinical acoustic parameters. The size-selected PCCAs through filtration are shown to preserve a sub-micron-sized (mean diameter  1 µm) that originate from native PCCA emulsion. The results demonstrate imaging signals with different amplitudes and temporal features compared to that of microbubbles. Compared with the microbubbles, both the B-mode and pulse-inversion (PI) signals from the vaporised PCCA populations were reduced significantly in the first tens of milliseconds, while only the B-mode signals from the PCCAs were recovered during the next 400 ms, suggesting significant changes to the size distribution of the PCCAs after vaporisation. It is also shown that such recovery in signal over time is not evident when using size-selective PCCAs. Furthermore, it was found that signals from the vaporised PCCA populations are affected by the amplitude and frame rate of the HFR ultrasound imaging. Using high-speed optical camera observation (30 kHz), we observed a change in particle size in the vaporised PCCA populations exposed to the HFR ultrasound imaging pulses. These findings can further the understanding of PCCA behaviour under HFR ultrasound imaging.

  19. Immobilization of trypsin on sub-micron skeletal polymer monolith

    Energy Technology Data Exchange (ETDEWEB)

    Yao Chunhe [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate School, Chinese Academy of Sciences, Beijing 100049 (China); Qi Li, E-mail: qili@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Hu Wenbin [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate School, Chinese Academy of Sciences, Beijing 100049 (China); Wang Fuyi [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yang Gengliang [College of Pharmacy, Hebei University, Baoding 071002 (China)

    2011-04-29

    A new kind of immobilized trypsin reactor based on sub-micron skeletal polymer monolith has been developed. Covalent immobilization of trypsin on this support was performed using the epoxide functional groups in either a one- or a multi-step reaction. The proteolytic activity of the immobilized trypsin was measured by monitoring the formation of N-{alpha}-benzoyl-L-arginine (BA) which is the digestion product of a substrate N-{alpha}-benzoyl-L-arginine ethyl ester (BAEE). Results showed that the digestion speed was about 300 times faster than that performed in free solution. The performance of such an enzyme reactor was further demonstrated by digesting protein myoglobin. It has been found that the protein digestion could be achieved in 88 s at 30 deg. C, which is comparable to 24 h digestion in solution at 37 {sup o}C. Furthermore, the immobilized trypsin exhibits increased stability even after continuous use compared to that in free solution. The present monolithic enzyme-reactor provides a promising platform for the proteomic research.

  20. Sub-micron resolution selected area electron channeling patterns.

    Science.gov (United States)

    Guyon, J; Mansour, H; Gey, N; Crimp, M A; Chalal, S; Maloufi, N

    2015-02-01

    Collection of selected area channeling patterns (SACPs) on a high resolution FEG-SEM is essential to carry out quantitative electron channeling contrast imaging (ECCI) studies, as it facilitates accurate determination of the crystal plane normal with respect to the incident beam direction and thus allows control the electron channeling conditions. Unfortunately commercial SACP modes developed in the past were limited in spatial resolution and are often no longer offered. In this contribution we present a novel approach for collecting high resolution SACPs (HR-SACPs) developed on a Gemini column. This HR-SACP technique combines the first demonstrated sub-micron spatial resolution with high angular accuracy of about 0.1°, at a convenient working distance of 10mm. This innovative approach integrates the use of aperture alignment coils to rock the beam with a digitally calibrated beam shift procedure to ensure the rocking beam is maintained on a point of interest. Moreover a new methodology to accurately measure SACP spatial resolution is proposed. While column considerations limit the rocking angle to 4°, this range is adequate to index the HR-SACP in conjunction with the pattern simulated from the approximate orientation deduced by EBSD. This new technique facilitates Accurate ECCI (A-ECCI) studies from very fine grained and/or highly strained materials. It offers also new insights for developing HR-SACP modes on new generation high-resolution electron columns. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Fabrication of sub-micron whole waffer SIS tunnel junctions for millimeter wave mixers

    International Nuclear Information System (INIS)

    Huq, S.E.; Blamire, M.G.; Evetts, J.E.; Hasko, D.G.; Ahmed, H.

    1991-01-01

    As a part of a programme for the development of a space-qualified sub-mm-wave mixer operating in the region of one terahertz we have been developing the processes required for the fabrication of submicron whole wafer tunnel junctions. Using the self-aligned whole-wafer process (SAWW) with electron beam lithography we have been able to reliably fabricate high quality (V m > 20 mV) submicron tunnel junctions from whole wafer Nb/AlO x /Nb structures. In particular we show that the junction quality is independent of size down to 0.3 μm 2 junction area. The problems of film stress, anodization, registration for electron beam lithography and lift-off, which limit the yield of good quality sub-micron scale junctions are addressed in this paper

  2. High intensity laser interactions with sub-micron droplets

    International Nuclear Information System (INIS)

    Mountford, L.C.

    1999-01-01

    A high-density source of liquid ethanol droplets has been developed, characterised and used in laser interaction studies for the first time. Mie Scattering and attenuation measurements show that droplets with a radius of (0.5 ± 0.1) μm and atomic densities of 10 19 atoms/cm 3 can be produced, bridging the gap between clusters and macroscopic solids. Lower density (10 16 cm -3 ) sprays can also be produced and these are electrostatically split into smaller droplets with a radius of (0.3 ± 0.1) μm. This work has been accepted for publication in Review of Scientific Instruments. A range of high intensity interaction experiments have been carried out with this unique sub-micron source. The absolute yield of keV x-rays, generated using 527 nm, 2 ps pulses focused to ∼10 17 W/cm 2 , was measured for the first time. ∼7 μJ of x-rays with photon energies above 1 keV were produced, comparable to yields obtained from much higher Z Xenon clusters. At intensities ≤10 16 W/cm 2 the yield from droplets exceeds that from solid targets of similar Z. The droplet medium is debris free and self-renewing, providing a suitable x-ray source for lithographic techniques. Due to the spacing between the droplets, it was expected that the droplet plasma temperature would exceed that of a solid target plasma, which is typically limited by rapid heat conduction to <1 keV. Analysis of the x-ray data shows this to be true with a mean droplet plasma temperature of (2 ± 0.8) keV, and a number of measurements exceeding 5 keV (to appear in Applied Physics Letters). The absorption of high intensity laser pulses in the dense spray has been measured for the first time and this was found to be wavelength and polarisation independent and in excess of 60%. These first interaction measurements clearly indicate that there are significant differences between the laser heating of droplet, solid and cluster targets. (author)

  3. 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 t...

  4. The evaluation of microstructure and mechanical properties of sintered sub-micron WC-Co powders

    International Nuclear Information System (INIS)

    Nor Izan Izura; Mohd Asri Selamat; Noraizham Mohamad Diah; Talib Ria Jaafar

    2007-01-01

    A cemented tungsten carbide (WC-Co) is widely used for a variety of machining, cutting, drilling and other applications. The properties of this tungsten heavy alloy are sensitive to processing and degraded by residual porosity. The sequence of high end powder metallurgy process include mixing, compacting and followed by multi-atmosphere sintering of green compact were analyzed. The sub micron (<1.0 μm) and less than 10.0 μm of WC powders are sintered with a metal binder 6% Co to provide pore-free part. The powder compacts were sintered at temperatures cycle in the range of 1200 degree Celsius-1550 degree Celsius in nitrogen-based sintering atmosphere. To date, however there have been few reported studies in the literature that the best sintering was carried out via liquid phase sintering in vacuum at approximately 1500 degree Celsius. from this study we found that in order to attain high mechanical properties, a fine grain size of powder is necessary. Therefore, the attention of this work is to develop and produce wear resistant component with better properties or comparable to the commercial ones. (author)

  5. Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

    International Nuclear Information System (INIS)

    Zheng Qi-Wen; Yu Xue-Feng; Cui Jiang-Wei; Guo Qi; Ren Di-Yuan; Cong Zhong-Chao; Zhou Hang

    2014-01-01

    Pattern imprinting in deep sub-micron static random access memories (SRAMs) during total dose irradiation is investigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell's static noise margin (SNM) and the background data, and study the influence of irradiation on the probability density function of ΔSNM, which is the difference between two data sides' SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation (STI) oxide rather than from the gate oxide of the micron-device. (condensed matter: structural, mechanical, and thermal properties)

  6. Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

    Science.gov (United States)

    Zheng, Qi-Wen; Yu, Xue-Feng; Cui, Jiang-Wei; Guo, Qi; Ren, Di-Yuan; Cong, Zhong-Chao; Zhou, Hang

    2014-10-01

    Pattern imprinting in deep sub-micron static random access memories (SRAMs) during total dose irradiation is investigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell's static noise margin (SNM) and the background data, and study the influence of irradiation on the probability density function of ΔSNM, which is the difference between two data sides' SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation (STI) oxide rather than from the gate oxide of the micron-device.

  7. Experimental study on reactor neutron induced effect of deep sub-micron CMOS static random access memory

    International Nuclear Information System (INIS)

    Yang Shanchao; Guo Xiaoqiang; Lin Dongsheng; Chen Wei; Li Ruibin; Bai Xiaoyan; Wang Guizhen

    2010-01-01

    This paper investigates neutron irradiation effects of two kinds of commercial CMOS SRAM (static random access memory), of which one is 4M memory with the feature size of 0.25 μm and the other is 16M memory with the feature size of 0.13 μm. We designed a memory testing system of irradiation effects and performed the neutron irradiation experiment using the Xi'an Pulse Reactor. The upset of two kinds of memory cells did not present a threshold versus the increase of neutron fluence. The results showed that deep sub-micron SRAM behaved single-event upset (SEU) effect in neutron irradiation environment. The SEU effect of SRAM with smaller size and higher integrated level tends to upset is considered to be related to the reduction of the device feature size, and fewer charges for upsets of the memory cell also lead to the SEU effect. (authors)

  8. X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

    Science.gov (United States)

    Dudak, J.; Karch, J.; Holcova, K.; Zemlicka, J.

    2017-12-01

    As X-ray micro-CT became a popular tool for scientific purposes a number of commercially available CT systems have emerged on the market. Micro-CT systems have, therefore, become widely accessible and the number of research laboratories using them constantly increases. However, even when CT scans with spatial resolution of several micrometers can be performed routinely, data acquisition with sub-micron precision remains a complicated task. Issues come mostly from prolongation of the scan time inevitably connected with the use of nano-focus X-ray sources. Long exposure time increases the noise level in the CT projections. Furthermore, considering the sub-micron resolution even effects like source-spot drift, rotation stage wobble or thermal expansion become significant and can negatively affect the data. The use of dark-current free photon counting detectors as X-ray cameras for such applications can limit the issue of increased image noise in the data, however the mechanical stability of the whole system still remains a problem and has to be considered. In this work we evaluate the performance of a micro-CT system equipped with nano-focus X-ray tube and a large area photon counting detector Timepix for scans with effective pixel size bellow one micrometer.

  9. Highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles

    Science.gov (United States)

    Huang, Yuewang; Zhao, Qiancheng; Sharac, Nicholas; Ragan, Regina; Boyraz, Ozdal

    2015-05-01

    We demonstrate the fabrication of a highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles for plasmonic enhancement. The average enhancement effect is evaluated by measuring the spectral broadening effect caused by self-phase-modulation. The nonlinear refractive index n2 was measured to be 7.0917×10-19 m2/W for a waveguide whose Wopen is 5 μm. Several waveguides at different locations on one wafer were measured in order to take the randomness of the nanoparticle distribution into consideration. The largest enhancement is measured to be as high as 10 times. Fabrication of this waveguide started with a MEMS grade photomask. By using conventional optical lithography, the wide linewidth was transferred to a wafer. Then the wafer was etched anisotropically by potassium hydroxide (KOH) to engrave trapezoidal trenches with an angle of 54.7º. Side wall roughness was mitigated by KOH etching and thermal oxidation that was used to generate a buffer layer for silicon nitride waveguide. The guiding material silicon nitride was then deposited by low pressure chemical vapor deposition. The waveguide was then patterned with a chemical template, with 20 nm gold particles being chemically attached to the functionalized poly(methyl methacrylate) domains. Since the particles attached only to the PMMA domains, they were confined to localized regions, therefore forcing the nanoparticles into clusters of various numbers and geometries. Experiments reveal that the waveguide has negligible nonlinear absorption loss, and its nonlinear refractive index can be greatly enhanced by gold nano clusters. The silicon nitride trench waveguide has large nonlinear refractive index, rendering itself promising for nonlinear applications.

  10. Sub-micron accurate track navigation method ''Navi'' for the analysis of Nuclear Emulsion

    International Nuclear Information System (INIS)

    Yoshioka, T; Yoshida, J; Kodama, K

    2011-01-01

    Sub-micron accurate track navigation in Nuclear Emulsion is realized by using low energy signals detected by automated Nuclear Emulsion read-out systems. Using those much dense ''noise'', about 10 4 times larger than the real tracks, the accuracy of the track position navigation reaches to be sub micron only by using the information of a microscope field of view, 200 micron times 200 micron. This method is applied to OPERA analysis in Japan, i.e. support of human eye checks of the candidate tracks, confirmation of neutrino interaction vertexes and to embed missing track segments to the track data read-out by automated systems.

  11. Sub-micron accurate track navigation method ``Navi'' for the analysis of Nuclear Emulsion

    Science.gov (United States)

    Yoshioka, T.; Yoshida, J.; Kodama, K.

    2011-03-01

    Sub-micron accurate track navigation in Nuclear Emulsion is realized by using low energy signals detected by automated Nuclear Emulsion read-out systems. Using those much dense ``noise'', about 104 times larger than the real tracks, the accuracy of the track position navigation reaches to be sub micron only by using the information of a microscope field of view, 200 micron times 200 micron. This method is applied to OPERA analysis in Japan, i.e. support of human eye checks of the candidate tracks, confirmation of neutrino interaction vertexes and to embed missing track segments to the track data read-out by automated systems.

  12. Synthesis and characterization of hollow {alpha}-Fe{sub 2}O{sub 3} sub-micron spheres prepared by sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Lizbet, E-mail: lizbetlf@gmail.com; Bustamante, Angel; Osorio, Ana; Olarte, G. S. [Universidad Nacional Mayor de San Marcos (Peru); Santos Valladares, Luis De Los, E-mail: ld301@cam.ac.uk; Barnes, Crispin H. W. [University of Cambridge, Cavendish Laboratory (United Kingdom); Majima, Yutaka [Tokyo Institute of Technology, Materials and Structures Laboratory (Japan)

    2011-11-15

    In this work we report the preparation of magnetic hematite hollow sub-micron spheres ({alpha}-Fe{sub 2}O{sub 3}) by colloidal suspensions of ferric nitrate nine-hydrate (Fe(NO{sub 3}){sub 3}{center_dot}9H{sub 2}O) particles in citric acid solution by following the sol-gel method. After the gel formation, the samples were annealed at different temperatures in an oxidizing atmosphere. Annealing at 180 Degree-Sign C resulted in an amorphous phase, without iron oxide formation. Annealing at 250 Degree-Sign C resulted in coexisting phases of hematite, maghemite and magnetite, whereas at 400 Degree-Sign C, only hematite and maghemite were found. Pure hematite hollow sub-micron spheres with porous shells were formed after annealing at 600 Degree-Sign C. The characterization was performed by X-ray diffraction (XRD), Moessbauer spectroscopy (MS) and scanning electron microscopy (SEM).

  13. Bacterial growth and motility in sub-micron constrictions

    NARCIS (Netherlands)

    Männik, J.; Driessen, R.; Galajda, P.; Keymer, J.E.; Dekker, C.

    2009-01-01

    In many naturally occurring habitats, bacteria live in micrometer-size confined spaces. Although bacterial growth and motility in such constrictions is of great interest to fields as varied as soil microbiology, water purification, and biomedical research, quantitative studies of the effects of

  14. Characteristics of scandate-impregnated cathodes with sub-micron scandia-doped matrices

    International Nuclear Information System (INIS)

    Yuan Haiqing; Gu Xin; Pan Kexin; Wang Yiman; Liu Wei; Zhang Ke; Wang Jinshu; Zhou Meiling; Li Ji

    2005-01-01

    We describe in this paper scandate-impregnated cathodes with sub-micron scandia-doped tungsten matrices having an improved uniformity of the Sc distribution. The scandia-doped tungsten powders were made by both liquid-solid doping and liquid-liquid doping methods on the basis of previous research. By improving pressing, sintering and impregnating procedures, we have obtained scandate-impregnated cathodes with a good uniformity of the Sc 2 O 3 - distribution. The porosity of the sub-micron structure matrix and content of impregnants inside the matrix are similar to those of conventionally impregnated cathodes. Space charge limited current densities of more than 30 A/cm 2 at 850 deg. C b have been obtained in a reproducible way. The current density continuously increases during the first 2000 h life test at 950 deg. C b with a dc load of 2 A/cm 2 and are stable for at least 3000 h

  15. Deep sub-micron FD-SOI for front-end application

    International Nuclear Information System (INIS)

    Ikeda, H.; Arai, Y.; Hara, K.; Hayakawa, H.; Hirose, K.; Ikegami, Y.; Ishino, H.; Kasaba, Y.; Kawasaki, T.; Kohriki, T.; Martin, E.; Miyake, H.; Mochizuki, A.; Tajima, H.; Tajima, O.; Takahashi, T.; Takashima, T.; Terada, S.; Tomita, H.; Tsuboyama, T.

    2007-01-01

    In order to confirm benefits of a deep sub-micron FD-SOI and to identify possible issues concerning front-end circuits with the FD-SOI, we have submitted a small design to Oki Electric Industry Co., Ltd. via the multi-chip project service of VDEC, the University of Tokyo. The initial test results and future plans for development are presented

  16. Sub-micron indent induced plastic deformation in copper and irradiated steel

    International Nuclear Information System (INIS)

    Robertson, Ch.

    1998-09-01

    In this work we aim to study the indent induced plastic deformation. For this purpose, we have developed a new approach, whereby the indentation curves provides the mechanical behaviour, while the deformation mechanisms are observed thanks to Transmission Electron Microscopy (TEM). In order to better understand how an indent induced dislocation microstructure forms, numerical modeling of the indentation process at the scale of discrete dislocations has been worked out as well. Validation of this modeling has been performed through direct comparison of the computed microstructures with TEM micrographs of actual indents in pure Cu [001]. Irradiation induced modifications of mechanical behaviour of ion irradiated 316L have been investigated, thanks to the mentioned approach. An important hardening effect was reported from indentation data (about 50%), on helium irradiated 316L steel. TEM observations of the damage zone clearly show that this behaviour is associated with the presence of He bubbles. TEM observations of the indent induced plastic zone also showed that the extent of the plastic zone is strongly correlated with hardness, that is to say: harder materials gets a smaller plastic zone. These results thus clearly established that the selected procedure can reveal any irradiation induced hardening in sub-micron thick ion irradiated layers. The behaviour of krypton irradiated 316L steel is somewhat more puzzling. In one hand indeed, a strong correlation between the defect cluster size and densities on the irradiation temperature is observed in the 350 deg C -600 deg C range, thanks to TEM observations of the damage zone. On the other hand, irradiation induced hardening reported from indentation data is relatively small (about 10%) and shows no dependence upon the irradiation temperature (within the mentioned range). In addition, it has been shown that the reported hardening vanishes following appropriate post-irradiation annealing, although most of the TEM

  17. Dense plasma focus x-ray source for sub-micron lithography

    International Nuclear Information System (INIS)

    Prasad, R.R.; Krishnan, M.; Mangano, J.; Greene, P.; Qi, Niansheng

    1993-01-01

    A discharge driven, dense plasma focus in neon is under development at SRL for use as a point x-ray source for sub-micron lithography. This source is presently capable of delivering ∼ 13j/pulse of neon K-shell x-rays (8--14 angstrom) into 4π steradians with 2 kj of electrical energy stored in the capacitor bank charged to 9 kV at a pulse repetition rate of 2 Hz. The discharge is produced by a ≤4 kj, ≤12 kV, capacitor bank circuit, which has a fixed inductance of 12 nH and drives ≤450 kA currents into the DPF load, with ∼1.1 μs rise-times. X-rays are produced when a dense pinch of neon is formed along the axis of the DPF electrodes. A new rail-gap switched capacitor bank and DPF have been built, designed for continuous operation at 2 Hz and burst mode operation at 20 Hz. This paper will present measurements of the x-ray output at a repetition rate of 2 Hz using the new capacitor bank. It will also describe measurements of the spot size (0.3--0.8 mm) and the spectrum (8--14 angstrom) of the DPF source. The dependence of these parameters on the DPF head geometry, bank energy and operating pressure will be discussed. The x-ray output has been measured using filtered pin diodes, x-ray diodes, and absolutely calibrated x-ray crystal spectra. Results from the source operating at 2 Hz will be presented. A novel concept of a windowless beamline has also been developed. The results of preliminary experiments to test the concept will be discussed. At a pulse repetition rate of 20 Hz, this source should produce 200--400 W of x-ray power in the 8-14 angstrom wavelength band, with an input power of 40--60 kW

  18. The effect of arsenic thermal diffusion on the morphology and photoluminescence properties of sub-micron ZnO rods

    Energy Technology Data Exchange (ETDEWEB)

    Ding Meng [Department of Physics, Jilin University, Changchun 130023 (China); Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130021 (China); Yao Bin, E-mail: binyao@jlu.edu.c [Department of Physics, Jilin University, Changchun 130023 (China); Zhao Dongxu, E-mail: dxzhao2000@yahoo.com.c [Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130021 (China); Fang Fang; Shen Dezhen; Zhang Zhenzhong [Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130021 (China)

    2010-05-31

    As-doped sub-micron ZnO rods were realized by a simple thermal diffusion process using a GaAs wafer as an arsenic resource. The surface of the sub-micron ZnO rods became rough and the morphology of As-doped sub-micron ZnO rods changed markedly with increasing diffusion temperature. From the results of energy-dispersive X-ray spectroscopy, X-ray diffraction and photoluminescence, arsenic elements were confirmed to be introduced into the sub-micron ZnO rods. The acceptor ionization energy was deduced to be about 110 meV based on the temperature-dependent PL spectra.

  19. The effect of arsenic thermal diffusion on the morphology and photoluminescence properties of sub-micron ZnO rods

    International Nuclear Information System (INIS)

    Ding Meng; Yao Bin; Zhao Dongxu; Fang Fang; Shen Dezhen; Zhang Zhenzhong

    2010-01-01

    As-doped sub-micron ZnO rods were realized by a simple thermal diffusion process using a GaAs wafer as an arsenic resource. The surface of the sub-micron ZnO rods became rough and the morphology of As-doped sub-micron ZnO rods changed markedly with increasing diffusion temperature. From the results of energy-dispersive X-ray spectroscopy, X-ray diffraction and photoluminescence, arsenic elements were confirmed to be introduced into the sub-micron ZnO rods. The acceptor ionization energy was deduced to be about 110 meV based on the temperature-dependent PL spectra.

  20. New constraints on deformation processes in serpentinite from sub-micron Raman Spectroscopy and TEM

    Science.gov (United States)

    Smith, S. A. F.; Tarling, M.; Rooney, J. S.; Gordon, K. C.; Viti, C.

    2017-12-01

    Extensive work has been performed to characterize the mineralogical and mechanical properties of the various serpentine minerals (i.e. antigorite, lizardite, chrysotile, polyhedral and polygonal serpentine). However, correct identification of serpentine minerals is often difficult or impossible using conventional analytical techniques such as optical- and SEM-based microscopy, X-ray diffraction and infrared spectroscopy. Transmission Electron Microscopy (TEM) is the best analytical technique to identify the serpentine minerals, but TEM requires complex sample preparation and typically results in very small analysis areas. Sub-micron confocal Raman spectroscopy mapping of polished thin sections provides a quick and relatively inexpensive way of unambiguously distinguishing the main serpentine minerals within their in-situ microstructural context. The combination of high spatial resolution (with a diffraction-limited system, 366 nm), large-area coverage (up to hundreds of microns in each dimension) and ability to map directly on thin sections allows intricate fault rock textures to be imaged at a sample-scale, which can then form the target of more focused TEM work. The potential of sub-micron Raman Spectroscopy + TEM is illustrated by examining sub-micron-scale mineral intergrowths and deformation textures in scaly serpentinites (e.g. dissolution seams, mineral growth in pressure shadows), serpentinite crack-seal veins and polished fault slip surfaces from a serpentinite-bearing mélange in New Zealand. The microstructural information provided by these techniques has yielded new insights into coseismic dehydration and amorphization processes and the interplay between creep and localised rupture in serpentinite shear zones.

  1. Modelling of passive heating for replication of sub-micron patterns in optical disk substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Youngmin; Bae, Jaecheol; Kim, Hongmin; Kang, Shinill [School of Mechanical Engineering, Yonsei University, 134 Shinchon-dong, Seodaemoon-ku, Seoul (Korea, Republic of)

    2004-05-07

    The transcribability of pit or land groove structures in replicating an optical disk substrate greatly affects the performance of a high-density optical disk. However, a solidified layer generated during the polymer filling worsens transcribability because the solidified layer prevents the polymer melt from filling the sub-micron patterns. Therefore, the development of the solidified layer during the filling stage of injection moulding must be delayed. For this delay, passive heating through an insulation layer has been used. In the present study, to examine the development of the solidified layer, delayed by passive heating, the flow of the polymer melt with passive heating was analysed. Passive heating delayed markedly the development of the solidified layer, reduced the viscosity of the polymer melt, and increased the fluidity of the polymer melt in the vicinity of the stamper surface with the sub-micron patterns. As a result, we predict that passive heating can improve the transcribability of an optical disk substrate. To verify our prediction, we fabricated an optical disk substrate by using passive heating of a mould and measured the transcribability of an optical disk substrate.

  2. Modelling of passive heating for replication of sub-micron patterns in optical disk substrates

    International Nuclear Information System (INIS)

    Kim, Youngmin; Bae, Jaecheol; Kim, Hongmin; Kang, Shinill

    2004-01-01

    The transcribability of pit or land groove structures in replicating an optical disk substrate greatly affects the performance of a high-density optical disk. However, a solidified layer generated during the polymer filling worsens transcribability because the solidified layer prevents the polymer melt from filling the sub-micron patterns. Therefore, the development of the solidified layer during the filling stage of injection moulding must be delayed. For this delay, passive heating through an insulation layer has been used. In the present study, to examine the development of the solidified layer, delayed by passive heating, the flow of the polymer melt with passive heating was analysed. Passive heating delayed markedly the development of the solidified layer, reduced the viscosity of the polymer melt, and increased the fluidity of the polymer melt in the vicinity of the stamper surface with the sub-micron patterns. As a result, we predict that passive heating can improve the transcribability of an optical disk substrate. To verify our prediction, we fabricated an optical disk substrate by using passive heating of a mould and measured the transcribability of an optical disk substrate

  3. Time-specific measurements of energy deposition from radiation fields in simulated sub-micron tissue volumes

    International Nuclear Information System (INIS)

    Famiano, M.A.

    1997-01-01

    A tissue-equivalent spherical proportional counter is used with a modified amplifier system to measure specific energy deposited from a uniform radiation field for short periods of time (∼1 micros to seconds) in order to extrapolate to dose in sub-micron tissue volumes. The energy deposited during these time intervals is compared to biological repair processes occurring within the same intervals after the initial energy deposition. The signal is integrated over a variable collection time which is adjusted with a square-wave pulse. Charge from particle passages is collected on the anode during the period in which the integrator is triggered, and the signal decays quickly to zero after the integrator feedback switch resets; the process repeats for every triggering pulse. Measurements of energy deposited from x rays, 137 Cs gamma rays, and electrons from a 90 Sr/ 90 Y source for various time intervals are taken. Spectral characteristics as a function of charge collection time are observed and frequency plots of specific energy and collection time-interval are presented. In addition, a threshold energy flux is selected for each radiation type at which the formation of radicals (based on current measurements) in mammalian cells equals the rate at which radicals are repaired

  4. Exploitation of sub-micron cavitation nuclei to enhance ultrasound-mediated transdermal transport and penetration of vaccines.

    Science.gov (United States)

    Bhatnagar, Sunali; Kwan, James J; Shah, Apurva R; Coussios, Constantin-C; Carlisle, Robert C

    2016-09-28

    Inertial cavitation mediated by ultrasound has been previously shown to enable skin permeabilisation for transdermal drug and vaccine delivery, by sequentially applying the ultrasound then the therapeutic in liquid form on the skin surface. Using a novel hydrogel dosage form, we demonstrate that the use of sub-micron gas-stabilising polymeric nanoparticles (nanocups) to sustain and promote cavitation activity during simultaneous application of both drug and vaccine results in a significant enhancement of both the dose and penetration of a model vaccine, Ovalbumin (OVA), to depths of 500μm into porcine skin. The nanocups themselves exceeded the penetration depth of the vaccine (up to 700μm) due to their small size and capacity to 'self-propel'. In vivo murine studies indicated that nanocup-assisted ultrasound transdermal vaccination achieved significantly (pultrasound-assisted vaccine delivery in the presence of nanocups demonstrated substantially higher specific anti-OVA IgG antibody levels compared to other transdermal methods. Further optimisation can lead to a viable, safe and non-invasive delivery platform for vaccines with potential use in a primary care setting or personalized self-vaccination at home. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  5. EFFECTS OF EFFECTS OF PARTICLE SIZE DISTRIBUTION ...

    African Journals Online (AJOL)

    eobe

    The parameters examined were: moisture content, particle size distribution, total isture content, particle size distribution, total hydrocarbon content, soil pH, available nitrogen, available phosphorus, total heterotrophic bacteria and fungi count. The analysis of the soil characteristics throughout the remediation period showed ...

  6. 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.

  7. Sub-micron silicon nitride waveguide fabrication using conventional optical lithography.

    Science.gov (United States)

    Huang, Yuewang; Zhao, Qiancheng; Kamyab, Lobna; Rostami, Ali; Capolino, Filippo; Boyraz, Ozdal

    2015-03-09

    We demonstrate a novel technique to fabricate sub-micron silicon nitride waveguides using conventional contact lithography with MEMS-grade photomasks. Potassium hydroxide anisotropic etching of silicon facilitates line reduction and roughness smoothing and is key to the technique. The fabricated waveguides is measured to have a propagation loss of 0.8dB/cm and nonlinear coefficient of γ = 0.3/W/m. A low anomalous dispersion of <100ps/nm/km is also predicted. This type of waveguide is highly suitable for nonlinear optics. The channels naturally formed on top of the waveguide also make it promising for plasmonics and quantum efficiency enhancement in sensing applications.

  8. Design consideration for dc SQUIDs fabricated in deep sub-micron technology

    International Nuclear Information System (INIS)

    Ketchen, M.B.

    1991-01-01

    Design rules for scaling dc SQUID junctions to optimize SQUID performance have been well known for over a decade, and verified down to the sub-micron regime. Practical SQUIDs having well coupled input coils of usable inductance have generally been fabricated at the 2-5 μm level of lithography. Other technologies, silicon in particular, are now routinely practiced at the 0.5 μm level of lithography with impressive demonstrations at the 0.1-0.25 μm level not uncommon. In this paper the implications of applying such fabrication capability to advance dc SQUID technology are explored. In particular the issues of scaling practical dc SQUIDs down to the 0.1-0.25 μm regime are examined, using as a prototype design the basic washer SQUID with a spiral input coil

  9. Occurrence of weak, sub-micron, tropospheric aerosol events at high Arctic latitudes

    Science.gov (United States)

    O'Neill, N. T.; Pancrati, O.; Baibakov, K.; Eloranta, E.; Batchelor, R. L.; Freemantle, J.; McArthur, L. J. B.; Strong, K.; Lindenmaier, R.

    2008-07-01

    Numerous fine mode (sub-micron) aerosol optical events were observed during the summer of 2007 at the High Arctic atmospheric observatory (PEARL) located at Eureka, Nunavut, Canada. Half of these events could be traced to forest fires in southern and eastern Russia and the Northwest Territories of Canada. The most notable findings were that (a) a combination of ground-based measurements (passive sunphotometry, high spectral resolution lidar) could be employed to determine that weak (near sub-visual) fine mode events had occurred, and (b) this data combined with remote sensing imagery products (MODIS, OMI-AI, FLAMBE fire sources), Fourier transform spectroscopy and back trajectories could be employed to identify the smoke events.

  10. Hot carrier degradation and a new lifetime prediction model in ultra-deep sub-micron pMOSFET

    International Nuclear Information System (INIS)

    Lei Xiao-Yi; Liu Hong-Xia; Zhang Kai; Zhang Yue; Zheng Xue-Feng; Ma Xiao-Hua; Hao Yue

    2013-01-01

    The hot carrier effect (HCE) of an ultra-deep sub-micron p-channel metal—oxide semiconductor field-effect transistor (pMOSFET) is investigated in this paper. Experiments indicate that the generation of positively charged interface states is the predominant mechanism in the case of the ultra-deep sub-micron pMOSFET. The relation of the pMOSFET hot carrier degradation to stress time (t), channel width (W), channel length (L), and stress voltage (V d ) is then discussed. Based on the relation, a lifetime prediction model is proposed, which can predict the lifetime of the ultra-deep sub-micron pMOSFET accurately and reflect the influence of the factors on hot carrier degradation directly. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  11. Sub-micron-sized delafossite CuCrO2 with different morphologies ...

    Indian Academy of Sciences (India)

    Abstract. Currently, copper chromium oxide crystallizing in delafossite structure attracts huge research interest due to its versatile applications arising from its layered structure. In this work, delafossite CuCrO2 was synthesized by sol–gel method from their respective hydrated nitrate salts with citric acid as a chelating agent.

  12. Sub-micron-sized delafossite CuCrO2 with different morphologies ...

    Indian Academy of Sciences (India)

    Currently, copper chromium oxide crystallizing in delafossite structure attracts huge research interest due to its versatile applications arising from its layered structure. In this work, delafossite CuCrO 2 was synthesized by sol–gel method from their respective hydrated nitrate salts with citric acid as a chelating agent.

  13. Particle size distribution of plutonium contaminated soil

    International Nuclear Information System (INIS)

    Zeng Ke; Wu Wangsuo; Jin Yuren; Shen Maoquan; Han Zhaoyang; Hu Zhiqian; Ma Teqi

    2012-01-01

    Wet classification and γ ray spectroscopy had been applied to study the particle size distribution of Pu in the desert soil of somewhere in Northern China. It was found that nearly 90% of Pu exits in 0.1-10 mm particles. only 10% less in particles under 0.05 mm that still poses notable hazards to biosphere if any resuspension. Providing a decontamination target of 239 Pu <4000 Bq/kg, accident condition. (authors)

  14. Particle sizes in slash fire smoke.

    Science.gov (United States)

    David V. Sandberg; Robert E. Martin

    1975-01-01

    Particulate emissions are the most objectionable atmospheric contaminant from forest burning. Little is known of the particulate sizes, and this research was done under laboratory conditions to obtain particle size information. Comments are made concerning techniques for future work in this field.

  15. MICRON-SIZED POLYMER PARTICLES FROM TANZANIAN ...

    African Journals Online (AJOL)

    Micron sized polymeric particles were prepared from cashew nut shell liquid and subsequently functionalized to produce micron-sized carboxylated cation exchange resin (MCCER). By titrimetry and analytical procedures employing atomic absorption spectrometry, an assessment of the cation exchange capability of the ...

  16. Suppression of coffee ring: (Particle) size matters

    Science.gov (United States)

    Bansal, Lalit; Seth, Pranjal; Murugappan, Bhubesh; Basu, Saptarshi

    2018-05-01

    Coffee ring patterns in drying sessile droplets are undesirable in various practical applications. Here, we experimentally demonstrate that on hydrophobic substrates, the coffee ring can be suppressed just by increasing the particle diameter. Particles with larger size flocculate within the evaporation timescale, leading to a significant gravimetric settling (for Pe > 1) triggering a uniform deposit. Interestingly, the transition to a uniform deposit is found to be independent of the internal flow field and substrate properties. Flocculation of particles also alters the particle packing at the nanoscale resulting in order to disorder transitions. In this letter, we exhibit a physical exposition on how particle size affects morphodynamics of the droplet drying at macro-nano length scales.

  17. Sub-micron Hard X-ray Fluorescence Imaging of Synthetic Elements

    Science.gov (United States)

    Jensen, Mark P.; Aryal, Baikuntha P.; Gorman-Lewis, Drew; Paunesku, Tatjana; Lai, Barry; Vogt, Stefan; Woloschak, Gayle E.

    2013-01-01

    Synchrotron-based X-ray fluorescence microscopy (SXFM) using hard X-rays focused into sub-micron spots is a powerful technique for elemental quantification and mapping, as well as microspectroscopic measurement such as μ-XANES (X-ray absorption near edge structure). We have used SXFM to image and simultaneously quantify the transuranic element plutonium at the L3 or L2 edge as well as lighter biologically essential elements in individual rat pheochromocytoma (PC12) cells after exposure to the long-lived plutonium isotope 242Pu. Elemental maps reveal that plutonium localizes principally in the cytoplasm of the cells and avoids the cell nucleus, which is marked by the highest concentrations of phosphorus and zinc, under the conditions of our experiments. The minimum detection limit under typical acquisition conditions for an average 202 μm2 cell is 1.4 fg Pu/cell or 2.9 × 10−20 moles Pu/μm2, which is similar to the detection limit of K-edge SXFM of transition metals at 10 keV. Copper electron microscopy grids were used to avoid interference from gold X-ray emissions, but traces of strontium present in naturally occurring calcium can still interfere with plutonium detection using its Lα X-ray emission. PMID:22444530

  18. Scalable Sub-micron Patterning of Organic Materials Toward High Density Soft Electronics.

    Science.gov (United States)

    Kim, Jaekyun; Kim, Myung-Gil; Kim, Jaehyun; Jo, Sangho; Kang, Jingu; Jo, Jeong-Wan; Lee, Woobin; Hwang, Chahwan; Moon, Juhyuk; Yang, Lin; Kim, Yun-Hi; Noh, Yong-Young; Jaung, Jae Yun; Kim, Yong-Hoon; Park, Sung Kyu

    2015-09-28

    The success of silicon based high density integrated circuits ignited explosive expansion of microelectronics. Although the inorganic semiconductors have shown superior carrier mobilities for conventional high speed switching devices, the emergence of unconventional applications, such as flexible electronics, highly sensitive photosensors, large area sensor array, and tailored optoelectronics, brought intensive research on next generation electronic materials. The rationally designed multifunctional soft electronic materials, organic and carbon-based semiconductors, are demonstrated with low-cost solution process, exceptional mechanical stability, and on-demand optoelectronic properties. Unfortunately, the industrial implementation of the soft electronic materials has been hindered due to lack of scalable fine-patterning methods. In this report, we demonstrated facile general route for high throughput sub-micron patterning of soft materials, using spatially selective deep-ultraviolet irradiation. For organic and carbon-based materials, the highly energetic photons (e.g. deep-ultraviolet rays) enable direct photo-conversion from conducting/semiconducting to insulating state through molecular dissociation and disordering with spatial resolution down to a sub-μm-scale. The successful demonstration of organic semiconductor circuitry promise our result proliferate industrial adoption of soft materials for next generation electronics.

  19. Prediction of total dose effects on sub-micron process metal oxide semiconductor devices

    International Nuclear Information System (INIS)

    Kamimura, Hiroshi; Kato, Masataka.

    1991-01-01

    A method for correcting leakage currents is described to predict the radiation-induced threshold voltage shift of sub-micron MOSFETs. A practical model for predicting the leakage current generated by irradiation is also given on the basis of experimental results on 0.8-μm process MOSFETs. The constants in the threshold voltage shift model are determined from the 'true' I-V characteristic of the MOSFET, which is obtained by correction of leakage currents due to characteristic change of a parasitic transistor. In this way, the threshold voltage shift of the n-channel MOSFET irradiated at a low dose rate of 2 Gy(Si)/h was also calculated by using data from a high dose rate irradiation experiment (100 Gy(Si)/h, 5 h). The calculated result well represented the tendency of measured data on threshold voltage shift. The radiation-induced leakage current was considered to decay approximately in two exponential modes. The constants in this leakage current model were determined from the above high dose rate experiment. The response of leakage current predicted at a low dose rate of 2 Gy(Si)/h approximately agreed with that measured during and after irradiation. (author)

  20. Large area sub-micron chemical imaging of magnesium in sea urchin teeth.

    Science.gov (United States)

    Masic, Admir; Weaver, James C

    2015-03-01

    The heterogeneous and site-specific incorporation of inorganic ions can profoundly influence the local mechanical properties of damage tolerant biological composites. Using the sea urchin tooth as a research model, we describe a multi-technique approach to spatially map the distribution of magnesium in this complex multiphase system. Through the combined use of 16-bit backscattered scanning electron microscopy, multi-channel energy dispersive spectroscopy elemental mapping, and diffraction-limited confocal Raman spectroscopy, we demonstrate a new set of high throughput, multi-spectral, high resolution methods for the large scale characterization of mineralized biological materials. In addition, instrument hardware and data collection protocols can be modified such that several of these measurements can be performed on irregularly shaped samples with complex surface geometries and without the need for extensive sample preparation. Using these approaches, in conjunction with whole animal micro-computed tomography studies, we have been able to spatially resolve micron and sub-micron structural features across macroscopic length scales on entire urchin tooth cross-sections and correlate these complex morphological features with local variability in elemental composition. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Vibro-spring particle size distribution analyser

    International Nuclear Information System (INIS)

    Patel, Ketan Shantilal

    2002-01-01

    This thesis describes the design and development of an automated pre-production particle size distribution analyser for particles in the 20 - 2000 μm size range. This work is follow up to the vibro-spring particle sizer reported by Shaeri. In its most basic form, the instrument comprises a horizontally held closed coil helical spring that is partly filled with the test powder and sinusoidally vibrated in the transverse direction. Particle size distribution data are obtained by stretching the spring to known lengths and measuring the mass of the powder discharged from the spring's coils. The size of the particles on the other hand is determined from the spring 'intercoil' distance. The instrument developed by Shaeri had limited use due to its inability to measure sample mass directly. For the device reported here, modifications are made to the original configurations to establish means of direct sample mass measurement. The feasibility of techniques for measuring the mass of powder retained within the spring are investigated in detail. Initially, the measurement of mass is executed in-situ from the vibration characteristics based on the spring's first harmonic resonant frequency. This method is often erratic and unreliable due to the particle-particle-spring wall interactions and the spring bending. An much more successful alternative is found from a more complicated arrangement in which the spring forms part of a stiff cantilever system pivoted along its main axis. Here, the sample mass is determined in the 'static mode' by monitoring the cantilever beam's deflection following the wanton termination of vibration. The system performance has been optimised through the variations of the mechanical design of the key components and the operating procedure as well as taking into account the effect of changes in the ambient temperature on the system's response. The thesis also describes the design and development of the ancillary mechanisms. These include the pneumatic

  2. Sub-micron opto-chemical probes for studying living neurons

    Science.gov (United States)

    Hossein-Zadeh, M.; Delgado, J.; Schweizer, F.; Lieberman, R.

    2017-02-01

    We have fabricated sub-micron opto-chemical probes for pH, oxygen and calcium monitoring and demonstrated their application in intracellular and extracellular monitoring of neurons (cortical neuronal cultures and acute hippocampal slices). Using these probes, we have measured extracellular pH in the stratum radiatum of the CA1 region of mouse hippocampus upon stimulation of presynaptic Schaffer collateral axons. Synaptic transmission was monitored using standard electrophysiological techniques. We find that the local pH transiently changes in response to synaptic stimulation. In addition, the geometry of the functionalized region on the probe combined with high sensitivity imaging enables simultaneous monitoring of spatially adjacent but distinct compartments. As proof of concept we impaled cultured neurons with the probe measured calcium and pH inside as well as directly outside of neurons as we changed the pH and calcium concentration in the physiological solution in the perfusion chamber. As such these probes can be used to study the impact of the environment on both cellular and extra-cellular space. Additionally as the chemical properties of the surrounding medium can be controlled and monitored with high precision, these probes enable differential measurement of the target parameter referenced to a stable bath. This approach eliminates the uncertainties associated with non-chemical fluctuations in the fluorescent emission and result in a self-calibrated opto-chemical probe. We have also demonstrated multifunctional probes that are capable of measuring up to three parameters in the extracellular space in brain slices.

  3. An examination of the shrinking-core model of sub-micron aluminum combustion

    Science.gov (United States)

    Buckmaster, John; Jackson, Thomas L.

    2013-04-01

    We revisit the shrinking-core model of sub-micron aluminum combustion with particular attention to the mass flux balance at the reaction front which necessarily leads to a displacement velocity of the alumina shell surrounding the liquid aluminum. For the planar problem this displacement simply leads to an equal displacement of the entire alumina layer, and therefore a straightforward mathematical framework can be constructed. In this way we are able to construct a single curve which defines the burn time for arbitrary values of the diffusion coefficient of O atoms, the reaction rate, the characteristic length of the combustion field, and the O atom mass concentration within the alumina provided that it is much smaller than the aluminum density. This demonstrates a transition between a 'd 2-t' law for fast chemistry and a 'd-t' law for slow chemistry. For the spherical geometry, the one of physical interest, the outward displacement velocity creates not a simple displacement, but a stress field which, when examined within the framework of linear elasticity, strongly suggests the creation of internal cracking. We note that if the molten aluminum is pushed into these cracks by the high internal pressure characteristic of the stress field, its surface, where reaction occurs, could be fractal in nature and affect the fundamental nature of the burning law. Indeed, if this ingredient is added to the planar model, a single curve for the burn time can again be derived, and this describes a transition from a 'd 2-t' law to a 'd ν-t' law, where 0<ν<1.

  4. Grain orientation and strain measurements in sub-micron wide passivated individual aluminum test structures

    International Nuclear Information System (INIS)

    Tamura, N.; Valek, B.C.; Spolenak, R.; MacDowell, A.A.; Celestre, R.S.; Padmore, H.A.; Brown, W.L.; Marieb, T.; Bravman, J.C.; Batterman, B.W.; Patel, J.R.

    2001-01-01

    An X-ray microdiffraction dedicated beamline, combining white and monochromatic beam capabilities, has been built at the Advanced Light Source. The purpose of this beamline is to address the myriad of problems in Materials Science and Physics that require submicron x-ray beams for structural characterization. Many such problems are found in the general area of thin films and nano-materials. For instance, the ability to characterize the orientation and strain state in individual grains of thin films allows us to measure structural changes at a very local level. These microstructural changes are influenced heavily by such parameters as deposition conditions and subsequent treatment. The accurate measurement of strain gradients at the micron and sub-micron level finds many applications ranging from the strain state under nano-indenters to gradients at crack tips. Undoubtedly many other applications will unfold in the future as we gain experience with the capabilities and limitations of this instrument. We have applied this technique to measure grain orientation and residual stress in single grains of pure Al interconnect lines and preliminary results on post-electromigration test experiments are presented. It is shown that measurements with this instrument can be used to resolve the complete stress tensor (6 components) in a submicron volume inside a single grain of Al under a passivation layer with an overall precision of about 20 MPa. The microstructure of passivated lines appears to be complex, with grains divided into identifiable subgrains and noticeable local variations of both tensile/compressive and shear stresses within single grains

  5. Permeability of different size waste particles

    Directory of Open Access Journals (Sweden)

    Sabina Gavelytė

    2015-10-01

    Full Text Available The world and life style is changing, but the most popular disposal route for waste is landfill globally until now. We have to think about waste prevention and preparing for re-use or recycling firstly, according to the waste disposal hierarchy. Disposed waste to the landfill must be the last opportunity. In a landfill, during waste degradation processes leachate is formed that can potentially cause clogging of bottom drainage layers. To ensure stability of a landfill construction, the physical properties of its components have to be controlled. The hydrology of precipitation, evaporation, runoff and the hydraulic performance of the capping and liner materials are important controls of the moisture content. The water balance depends also on the waste characteristics and waste particle size distribution. The aim of this paper is to determine the hydraulic permeability in a landfill depending on the particle size distribution of municipal solid waste disposed. The lab experiment results were compared with the results calculated with DEGAS model. Samples were taken from a landfill operated for five years. The samples particle sizes are: >100 mm, 80 mm, 60 mm, 40 mm, 20 mm, 0.01 mm and <0.01 mm. The permeability test was conducted using the column test. The paper presents the results of experiment and DEGAS model water permeability with waste particle size.

  6. Remote Laser Diffraction Particle Size Distribution Analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Batcheller, Thomas Aquinas; Huestis, Gary Michael; Bolton, Steven Michael

    2001-03-01

    In support of a radioactive slurry sampling and physical characterization task, an “off-the-shelf” laser diffraction (classical light scattering) particle size analyzer was utilized for remote particle size distribution (PSD) analysis. Spent nuclear fuel was previously reprocessed at the Idaho Nuclear Technology and Engineering Center (INTEC—formerly recognized as the Idaho Chemical Processing Plant) which is on DOE’s INEEL site. The acidic, radioactive aqueous raffinate streams from these processes were transferred to 300,000 gallon stainless steel storage vessels located in the INTEC Tank Farm area. Due to the transfer piping configuration in these vessels, complete removal of the liquid can not be achieved. Consequently, a “heel” slurry remains at the bottom of an “emptied” vessel. Particle size distribution characterization of the settled solids in this remaining heel slurry, as well as suspended solids in the tank liquid, is the goal of this remote PSD analyzer task. A Horiba Instruments Inc. Model LA-300 PSD analyzer, which has a 0.1 to 600 micron measurement range, was modified for remote application in a “hot cell” (gamma radiation) environment. This technology provides rapid and simple PSD analysis, especially down in the fine and microscopic particle size regime. Particle size analysis of these radioactive slurries down in this smaller range was not previously achievable—making this technology far superior than the traditional methods used. Successful acquisition of this data, in conjunction with other characterization analyses, provides important information that can be used in the myriad of potential radioactive waste management alternatives.

  7. Prescribed 3-D Direct Writing of Suspended Micron/Sub-micron Scale Fiber Structures via a Robotic Dispensing System.

    Science.gov (United States)

    Yuan, Hanwen; Cambron, Scott D; Keynton, Robert S

    2015-06-12

    A 3-axis dispensing system is utilized to control the initiating and terminating fiber positions and trajectory via the dispensing software. The polymer fiber length and orientation is defined by the spatial positioning of the dispensing system 3-axis stages. The fiber diameter is defined by the prescribed dispense time of the dispensing system valve, the feed rate (the speed at which the stage traverses from an initiating to a terminating position), the gauge diameter of the dispensing tip, the viscosity and surface tension of the polymer solution, and the programmed drawing length. The stage feed rate affects the polymer solution's evaporation rate and capillary breakup of the filaments. The dispensing system consists of a pneumatic valve controller, a droplet-dispensing valve and a dispensing tip. Characterization of the direct write process to determine the optimum combination of factors leads to repeatedly acquiring the desired range of fiber diameters. The advantage of this robotic dispensing system is the ease of obtaining a precise range of micron/sub-micron fibers onto a desired, programmed location via automated process control. Here, the discussed self-assembled micron/sub-micron scale 3D structures have been employed to fabricate suspended structures to create micron/sub-micron fluidic devices and bioengineered scaffolds.

  8. Area- and energy-efficient CORDIC accelerators in deep sub-micron CMOS technologies

    Science.gov (United States)

    Vishnoi, U.; Noll, T. G.

    2012-09-01

    The COordinate Rotate DIgital Computer (CORDIC) algorithm is a well known versatile approach and is widely applied in today's SoCs for especially but not restricted to digital communications. Dedicated CORDIC blocks can be implemented in deep sub-micron CMOS technologies at very low area and energy costs and are attractive to be used as hardware accelerators for Application Specific Instruction Processors (ASIPs). Thereby, overcoming the well known energy vs. flexibility conflict. Optimizing Global Navigation Satellite System (GNSS) receivers to reduce the hardware complexity is an important research topic at present. In such receivers CORDIC accelerators can be used for digital baseband processing (fixed-point) and in Position-Velocity-Time estimation (floating-point). A micro architecture well suited to such applications is presented. This architecture is parameterized according to the wordlengths as well as the number of iterations and can be easily extended for floating point data format. Moreover, area can be traded for throughput by partially or even fully unrolling the iterations, whereby the degree of pipelining is organized with one CORDIC iteration per cycle. From the architectural description, the macro layout can be generated fully automatically using an in-house datapath generator tool. Since the adders and shifters play an important role in optimizing the CORDIC block, they must be carefully optimized for high area and energy efficiency in the underlying technology. So, for this purpose carry-select adders and logarithmic shifters have been chosen. Device dimensioning was automatically optimized with respect to dynamic and static power, area and performance using the in-house tool. The fully sequential CORDIC block for fixed-point digital baseband processing features a wordlength of 16 bits, requires 5232 transistors, which is implemented in a 40-nm CMOS technology and occupies a silicon area of 1560 μm2 only. Maximum clock frequency from circuit

  9. Influence of particle size in silo discharge

    Directory of Open Access Journals (Sweden)

    Gella Diego

    2017-01-01

    Full Text Available Recently Janda et al. [Phys. Rev. Lett. 108, 248001 (2012] reported an experimental study where it was measured the velocity and volume fraction fields of 1 mm diameter stainless steel beads in the exit of a two-dimensional silo. In that work, they proposed a new expression to predict the flow of granular media in silos which does not explicitly include the particle size as a parameter. Here, we study if effectively, there is not such influence of the particle size in the flux equations as well as investigate any possible effect in the velocity and volume fraction fields. To this end, we have performed high speed motion measurements of these magnitudes in a two-dimensional silo filled with 4 mm diameter beads of stainless steel, the same material than the previous works. A developed tracking program has been implemented to obtain at the same time both, the velocity and volume fraction. The final objective of this work has been to extend and generalize the theoretical framework of Janda et al. for all sizes of particles. We have found that the obtained functionalities are the same than in the 1 mm case, but the exponents and other fitting parameters are different.

  10. Size exclusion chromatography with superficially porous particles.

    Science.gov (United States)

    Schure, Mark R; Moran, Robert E

    2017-01-13

    A comparison is made using size-exclusion chromatography (SEC) of synthetic polymers between fully porous particles (FPPs) and superficially porous particles (SPPs) with similar particle diameters, pore sizes and equal flow rates. Polystyrene molecular weight standards with a mobile phase of tetrahydrofuran are utilized for all measurements conducted with standard HPLC equipment. Although it is traditionally thought that larger pore volume is thermodynamically advantageous in SEC for better separations, SPPs have kinetic advantages and these will be shown to compensate for the loss in pore volume compared to FPPs. The comparison metrics include the elution range (smaller with SPPs), the plate count (larger for SPPs), the rate production of theoretical plates (larger for SPPs) and the specific resolution (larger with FPPs). Advantages to using SPPs for SEC are discussed such that similar separations can be conducted faster using SPPs. SEC using SPPs offers similar peak capacities to that using FPPs but with faster operation. This also suggests that SEC conducted in the second dimension of a two-dimensional liquid chromatograph may benefit with reduced run time and with equivalently reduced peak width making SPPs advantageous for sampling the first dimension by the second dimension separator. Additional advantages are discussed for biomolecules along with a discussion of optimization criteria for size-based separations. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Particle-size distribution study: PILEDRIVER event

    Energy Technology Data Exchange (ETDEWEB)

    Rabb, David D [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

    1970-05-15

    Reentry was made by mining into the chimney of broken rock created by a nuclear detonation in granite at a depth of 1500 feet. The chimney was 160 ft in radius and 890 ft high. An injection of radioactive melt was encountered at 300 ft from shot point. Radiochemical analyses determined that the yield of PILEDRIVER nuclear device was 61 {+-} 10 kt. Two samples of chimney rubble totalling over 5,000 lb were obtained during the postshot exploration. These samples of broken granite underwent screen analysis, a radioactivity-distribution study, and cursory leaching tests. The two samples were separated into 25 different size-fractions. An average of the particle-size data from the two samples showed that 17% of the material is between 20 mesh and I in.; 42% between 1 and 6 in.; and 34% between 6 in. and 3 ft. The distribution of radioactivity varies markedly with the particle size. The minus 100-mesh material comprizes less than 1.5% of the weight but contains almost 20% of the radioactivity. Small-scale batch-leaching tests showed that 25% of the radioactivity could be removed in a few hours by a film-percolation leach with distilled water, and 40% with dilute acid. Brief studies were made of the microfractures in the broken rock and of the radioactivity created by the PILEDRIVER explosion. (author)

  12. Particle-size distribution study: PILEDRIVER event

    International Nuclear Information System (INIS)

    Rabb, David D.

    1970-01-01

    Reentry was made by mining into the chimney of broken rock created by a nuclear detonation in granite at a depth of 1500 feet. The chimney was 160 ft in radius and 890 ft high. An injection of radioactive melt was encountered at 300 ft from shot point. Radiochemical analyses determined that the yield of PILEDRIVER nuclear device was 61 ± 10 kt. Two samples of chimney rubble totalling over 5,000 lb were obtained during the postshot exploration. These samples of broken granite underwent screen analysis, a radioactivity-distribution study, and cursory leaching tests. The two samples were separated into 25 different size-fractions. An average of the particle-size data from the two samples showed that 17% of the material is between 20 mesh and I in.; 42% between 1 and 6 in.; and 34% between 6 in. and 3 ft. The distribution of radioactivity varies markedly with the particle size. The minus 100-mesh material comprizes less than 1.5% of the weight but contains almost 20% of the radioactivity. Small-scale batch-leaching tests showed that 25% of the radioactivity could be removed in a few hours by a film-percolation leach with distilled water, and 40% with dilute acid. Brief studies were made of the microfractures in the broken rock and of the radioactivity created by the PILEDRIVER explosion. (author)

  13. Spatial Variability of CCN Sized Aerosol Particles

    Science.gov (United States)

    Asmi, A.; Väänänen, R.

    2014-12-01

    The computational limitations restrict the grid size used in GCM models, and for many cloud types they are too large when compared to the scale of the cloud formation processes. Several parameterizations for e.g. convective cloud formation exist, but information on spatial subgrid variation of the cloud condensation nuclei (CCNs) sized aerosol concentration is not known. We quantify this variation as a function of the spatial scale by using datasets from airborne aerosol measurement campaigns around the world including EUCAARI LONGREX, ATAR, INCA, INDOEX, CLAIRE, PEGASOS and several regional airborne campaigns in Finland. The typical shapes of the distributions are analyzed. When possible, we use information obtained by CCN counters. In some other cases, we use particle size distribution measured by for example SMPS to get approximated CCN concentration. Other instruments used include optical particle counters or condensational particle counters. When using the GCM models, the CCN concentration used for each the grid-box is often considered to be either flat, or as an arithmetic mean of the concentration inside the grid-box. However, the aircraft data shows that the concentration values are often lognormal distributed. This, combined with the subgrid variations in the land use and atmospheric properties, might cause that the aerosol-cloud interactions calculated by using mean values to vary significantly from the true effects both temporary and spatially. This, in turn, can cause non-linear bias into the GCMs. We calculate the CCN aerosol concentration distribution as a function of different spatial scales. The measurements allow us to study the variation of these distributions within from hundreds of meters up to hundreds of kilometers. This is used to quantify the potential error when mean values are used in GCMs.

  14. High Proportions of Sub-micron Particulate Matter in Icelandic Dust Storms in 2015

    Science.gov (United States)

    Dagsson Waldhauserova, Pavla; Arnalds, Olafur; Olafsson, Haraldur; Magnusdottir, Agnes

    2017-04-01

    in situ measurements at the dust source in 2013 revealed extremely high number concentrations of submicron particles, specifically in the size range 0.3-0.337 μm. The PM2.5/PM10 ratios of mass concentrations seem to be lower at the dust sources that in some distance from the sources as measured in 2015. Common dust storms in Iceland are of several hundred thousand tons of magnitude from relatively well defined main dust sources. Numerical simulations were used calculate the total dust flux from the sources as 180,000 - 280,000 tons in this study. The mean PM1 (PM10) concentrations inside of the dust plumes varied from 97 to 241 µg m-3 (PM10 = 158 to 583 µg m-3). The extent of moderate dust events was calculated as 2.450 km2 to 4.220 km2 of the land area suggesting the regional scale of the events. Dust plumes reported here passed the most densely inhabited areas of Iceland, health risk warnings for the general public were, however, not issued. The data provided stresses the need for such warning system and is an important step towards its development.

  15. Particle size distribution control of Pt particles used for particle gun

    Science.gov (United States)

    Ichiji, M.; Akiba, H.; Nagao, H.; Hirasawa, I.

    2017-07-01

    The purpose of this study is particle size distribution (PSD) control of submicron sized Pt particles used for particle gun. In this report, simple reaction crystallization is conducted by mixing H2PtCl6 and ascorbic acid. Without the additive, obtained Pt particles have broad PSD and reproducibility of experiment is low. With seeding, Pt particles have narrow PSD and reproducibility improved. Additionally, mean particle diameter of 100-700 nm is controlled by changing seeding amount. Obtained particles are successfully characterized as Pt by XRD results. Moreover, XRD spectra indicate that obtained particles are polycrystals. These experimental results suggest that seeding consumed nucleation, as most nuclei attached on the seed surface. This mechanism virtually restricted nucleation to have narrow PSD can be obtained.

  16. The magnetic structure and palaeomagnetic recording fidelity of sub-micron greigite (Fe3S4)

    Science.gov (United States)

    Valdez-Grijalva, Miguel A.; Nagy, Lesleis; Muxworthy, Adrian R.; Williams, Wyn; Fabian, Karl

    2018-02-01

    We present the results of a finite-element micromagnetic model of 30nm to 300nm greigite (Fe3S4) grains with a variety of equant morphologies. This grain size range covers the magnetic single-domain (SD) to pseudo single-domain (PSD) transition, and possibly also the PSD to multi-domain (MD) transition. The SD-PSD threshold d0 is determined to be 50nm ≤d0 ≤ 56nm depending on grain shape. The nudged elastic-band method was used to determine the room temperature energy barriers between stable states and thus the blocking volumes. It is found that, in the absence of interparticle magnetostatic interactions, the magnetisation of equant SD greigite is not stable on a geological scale and only PSD grains ≥ 70nm can be expected to carry a stable magnetisation over billion-year timescales, i.e., all non-interacting SD particles are essentially superparamagnetic. We further identify a mechanism for the PSD to multi-domain (MD) transition, which is of a continuous nature from PSD nucleation up to 300nm, when structures typical of MD behaviour like closure domains begin to form.

  17. An alternative method for determining particle-size distribution of forest road aggregate and soil with large-sized particles

    Science.gov (United States)

    Hakjun Rhee; Randy B. Foltz; James L. Fridley; Finn Krogstad; Deborah S. Page-Dumroese

    2014-01-01

    Measurement of particle-size distribution (PSD) of soil with large-sized particles (e.g., 25.4 mm diameter) requires a large sample and numerous particle-size analyses (PSAs). A new method is needed that would reduce time, effort, and cost for PSAs of the soil and aggregate material with large-sized particles. We evaluated a nested method for sampling and PSA by...

  18. Automatic particle-size analysis of HTGR recycle fuel

    International Nuclear Information System (INIS)

    Mack, J.E.; Pechin, W.H.

    1977-09-01

    An automatic particle-size analyzer was designed, fabricated, tested, and put into operation measuring and counting HTGR recycle fuel particles. The particle-size analyzer can be used for particles in all stages of fabrication, from the loaded, uncarbonized weak acid resin up to fully-coated Biso or Triso particles. The device handles microspheres in the range of 300 to 1000 μm at rates up to 2000 per minute, measuring the diameter of each particle to determine the size distribution of the sample, and simultaneously determining the total number of particles. 10 figures

  19. Nonlinear resistivity in a d-wave superconductor YBa{sub 2}Cu{sub 4}O{sub 8} of sub-micron scale grains

    Energy Technology Data Exchange (ETDEWEB)

    Deguchi, H; Shoho, T; Kato, Y; Ashida, T; Mito, M; Takagi, S [Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Hagiwara, M [Faculty of Engineering and Design, Kyoto Institute of Technology, Kyoto 606-8585 (Japan); Koyama, K, E-mail: deguchi@tobata.isc.kyutech.ac.jp [Faculty of Integrated Arts and Science, The University of Tokushima 770-8502 (Japan)

    2011-07-20

    The d-wave ceramic YBa{sub 2}Cu{sub 4}O{sub 8} superconductor composed of sub-micron size grains is considered as random Josephson-coupled network of 0 and {pi} junctions and shows successive phase transitions. The upper transition occurs inside each grain at T{sub c1} = 82 K and the lower transition occurs among the grains at T{sub c2} = 66 K. We measured the temperature dependence of the current-voltage characteristics of the ceramic YBa{sub 2}Cu{sub 4}O{sub 8} and derived the linear and nonlinear resistivity. The nonlinear resistivity {rho}{sub 2} and {rho}{sub 4} have finite values between T{sub c1} and T{sub c2} and have the peak at the same temperature T{sub p} = 70 K above T{sub c2}. The result agrees with the theoretical one obtained by Li and DomInguez. They interpreted T{sub p} as the crossover temperature from the normal state phase to a chiral paramagnetic one.

  20. Concentration and size distribution of particles in abstracted groundwater.

    Science.gov (United States)

    van Beek, C G E M; de Zwart, A H; Balemans, M; Kooiman, J W; van Rosmalen, C; Timmer, H; Vandersluys, J; Stuyfzand, P J

    2010-02-01

    Particle number concentrations have been counted and particle size distributions calculated in groundwater derived by abstraction wells. Both concentration and size distribution are governed by the discharge rate: the higher this rate the higher the concentration and the higher the proportion of larger particles. However, the particle concentration in groundwater derived from abstraction wells, with high groundwater flow velocities, is much lower than in groundwater from monitor wells, with minimal flow velocities. This inconsistency points to exhaustion of the particle supply in the aquifer around wells due to groundwater abstraction for many years. The particle size distribution can be described with the help of a power law or Pareto distribution. Comparing the measured particle size distribution with the Pareto distribution shows that particles with a diameter >7 microm are under-represented. As the particle size distribution is dependent on the flow velocity, so is the value of the "Pareto" slope beta. (c) 2009 Elsevier Ltd. All rights reserved.

  1. Analysis of functional failure mode of commercial deep sub-micron SRAM induced by total dose irradiation

    International Nuclear Information System (INIS)

    Zheng Qi-Wen; Cui Jiang-Wei; Zhou Hang; Yu De-Zhao; Yu Xue-Feng; Lu Wu; Guo Qi; Ren Di-Yuan

    2015-01-01

    Functional failure mode of commercial deep sub-micron static random access memory (SRAM) induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize the functional failure mode of the device by testing its electrical parameters and function with test patterns covering different functional failure modes. Experimental results reveal that the functional failure mode of the device is a temporary function interruption caused by peripheral circuits being sensitive to the standby current rising. By including radiation-induced threshold shift and off-state leakage current in memory cell transistors, we simulate the influence of radiation on the functionality of the memory cell. Simulation results reveal that the memory cell is tolerant to irradiation due to its high stability, which agrees with our experimental result. (paper)

  2. 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: 3.089, year: 2016

  3. Automatic size analysis of coated fuel particles

    International Nuclear Information System (INIS)

    Wallisch, K.; Koss, P.

    1977-01-01

    The determination of the diameter, coating thickness, and sphericity of coated fuel particles by conventional methods is very time consuming. Therefore, statistical data can only be obtained with limited accuracy. An alternative method is described that avoids these disadvantages by utilizing a fast optical data-collecting system of high accuracy. This system allows the determination of the diameter of particles in the range between 100 and 1500 μm, with an accuracy of better than +-2 μm and with a rate of 100 particles per second. The density and thickness of coating layers can be determined by comparing the data obtained before and after coating, taking into account the relative increase of weight. A special device allows the automatic determination of the sphericity of single particles as well as the distribution in a batch. This device measures 50 to 100 different diameters of each particle per second. An on-line computer stores the measured data and calculates all parameters required, e.g., number of particles measured, particle diameter, standard deviation, diameter limiting values, average particle volume, average particle surface area, and the distribution of sphericity in absolute and percent form

  4. Sub-micron-scale femtosecond laser ablation using a digital micromirror device

    International Nuclear Information System (INIS)

    Mills, B; Feinaeugle, M; Sones, C L; Eason, R W; Rizvi, N

    2013-01-01

    Commercial digital multimirror devices offer a cheap and effective alternative to more expensive spatial light modulators for ablation via beam shaping. Here we present femtosecond laser ablation using the digital multimirror device from an Acer C20 Pico Digital Light Projector and show ablation of complex features with feature sizes ranging from sub-wavelength (400 nm) up to ∼30 µm. Simulations are presented that have been used to optimize and understand the experimentally observed resolution. (paper)

  5. Effect of silica particle size on macrophage inflammatory responses.

    Directory of Open Access Journals (Sweden)

    Toshimasa Kusaka

    Full Text Available Amorphous silica particles, such as nanoparticles (<100 nm diameter particles, are used in a wide variety of products, including pharmaceuticals, paints, cosmetics, and food. Nevertheless, the immunotoxicity of these particles and the relationship between silica particle size and pro-inflammatory activity are not fully understood. In this study, we addressed the relationship between the size of amorphous silica (particle dose, diameter, number, and surface area and the inflammatory activity (macrophage phagocytosis, inflammasome activation, IL-1β secretion, cell death and lung inflammation. Irrespective of diameter size, silica particles were efficiently internalized by mouse bone marrow-derived macrophages via an actin cytoskeleton-dependent pathway, and induced caspase-1, but not caspase-11, activation. Of note, 30 nm-1000 nm diameter silica particles induced lysosomal destabilization, cell death, and IL-1β secretion at markedly higher levels than did 3000 nm-10000 nm silica particles. Consistent with in vitro results, intra-tracheal administration of 30 nm silica particles into mice caused more severe lung inflammation than that of 3000 nm silica particles, as assessed by measurement of pro-inflammatory cytokines and neutrophil infiltration in bronchoalveolar lavage fluid of mice, and by the micro-computed tomography analysis. Taken together, these results suggest that silica particle size impacts immune responses, with submicron amorphous silica particles inducing higher inflammatory responses than silica particles over 1000 nm in size, which is ascribed not only to their ability to induce caspase-1 activation but also to their cytotoxicity.

  6. Dependence of strength on particle size in graphite

    International Nuclear Information System (INIS)

    Kennedy, E.P.; Kennedy, C.R.

    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/cm 3 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

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

    DEFF Research Database (Denmark)

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

    1997-01-01

    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 superparamagnetic at finite temperatures. The temperature dependence of the superparamagnetic relaxation time and the influence of inter-particle interactions is discussed. Finally, some examples of studies of surface magnetization of alpha-Fe particles are presented....

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

    International Nuclear Information System (INIS)

    Knudsen, I.E.; Randall, C.C.

    1976-01-01

    A process is claimed for converting uranium hexafluoride (UF 6 ) to uranium dioxide (UO 2 ) 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

  9. Ultraviolet (UV) disinfection of grey water: particle size effects.

    Science.gov (United States)

    Winward, G P; Avery, L M; Stephenson, T; Jefferson, B

    2008-02-01

    The impact of water quality on the ultraviolet (UV) disinfection of grey water was investigated with reference to urban water reuse. Direct UV disinfection of grey water did not meet the stringent California State Title 22 criteria for unrestricted urban water reuse due to the presence of particulate material ranging from or = 2000 microm in size. Grey water was manipulated by settling to produce fractions of varying particle size distributions and blending was employed post-disinfection to extract particle-associated coliforms (PACs). The efficacy of UV disinfection was found to be linked to the particle size of the grey water fractions. The larger particle size fractions with a mean particle size of 262 microm and above were observed to shield more coliforms from UV light than did the smaller particles with a mean particle size below 119 microm. Up to 70% of total coliforms in the larger particle size fractions were particle-associated following a UV dose (fluence) of 260 mJ.cm(-2) and would remain undetected by standard coliform enumeration techniques. Implications for urban water reuse are discussed and recommendations made for grey water treatment to ensure removal of particle-associated indicator bacteria and pathogens prior to UV disinfection.

  10. The role of sub-micron grain size in the development of rare earth hard magnetic alloys

    International Nuclear Information System (INIS)

    Davies, H.A.; Wang, Z.C.

    2004-01-01

    The magnetic properties of nanocrystalline melt spun rare earth-iron-boron alloys based on Nd or Pr and on Nd-Pr mixtures are compared for a wide range of RE:Fe ratio. Their magnetic properties are compared with those of corresponding alloy ribbons based on Nd. The Pr containing alloys have generally higher coercivity than their Nd counterparts because of the higher anisotropy constant of the Pr 2 Fe 14 B phase. Co substitution for Fe increases the Curie temperature and thermal stability for the nanophase alloys. Excellent magnetic property combinations were achieved for single phase Pr 12 (Fe 100-x Co x ) 82 B 6 (x=0-20) alloys, processed by overquenching and devitrification annealing. In contrast, in the case of nanocomposite Pr 10 (Fe 100-x Co x ) 84 B 6 alloys, based on Pr 2 Fe 14 B/α-Fe mixtures, only for 30% substitution of Fe by Co could useful enhancement of (BH) max be achieved, due to generally rather coarse α-Fe crystallites

  11. Artificial neural network based particle size prediction of polymeric nanoparticles.

    Science.gov (United States)

    Youshia, John; Ali, Mohamed Ehab; Lamprecht, Alf

    2017-10-01

    Particle size of nanoparticles and the respective polydispersity are key factors influencing their biopharmaceutical behavior in a large variety of therapeutic applications. Predicting these attributes would skip many preliminary studies usually required to optimize formulations. The aim was to build a mathematical model capable of predicting the particle size of polymeric nanoparticles produced by a pharmaceutical polymer of choice. Polymer properties controlling the particle size were identified as molecular weight, hydrophobicity and surface activity, and were quantified by measuring polymer viscosity, contact angle and interfacial tension, respectively. A model was built using artificial neural network including these properties as input with particle size and polydispersity index as output. The established model successfully predicted particle size of nanoparticles covering a range of 70-400nm prepared from other polymers. The percentage bias for particle prediction was 2%, 4% and 6%, for the training, validation and testing data, respectively. Polymer surface activity was found to have the highest impact on the particle size followed by viscosity and finally hydrophobicity. Results of this study successfully highlighted polymer properties affecting particle size and confirmed the usefulness of artificial neural networks in predicting the particle size and polydispersity of polymeric nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Engineering design of sub-micron topographies for simultaneously adherent and reflective metal-polymer interfaces

    Science.gov (United States)

    Brown, Christopher A.

    1993-01-01

    The approach of the project is to base the design of multi-function, reflective topographies on the theory that topographically dependent phenomena react with surfaces and interfaces at certain scales. The first phase of the project emphasizes the development of methods for understanding the sizes of topographic features which influence reflectivity. Subsequent phases, if necessary, will address the scales of interaction for adhesion and manufacturing processes. A simulation of the interaction of electromagnetic radiation, or light, with a reflective surface is performed using specialized software. Reflectivity of the surface as a function of scale is evaluated and the results from the simulation are compared with reflectivity measurements made on multi-function, reflective surfaces.

  13. Seasonal and particle size-dependent variations in gas/particle partitioning of PCDD/Fs

    International Nuclear Information System (INIS)

    Lee, Se-Jin; Ale, Debaki; Chang, Yoon-Seok; Oh, Jeong-Eun; Shin, Sun Kyoung

    2008-01-01

    This study monitored particle size-dependent variations in atmospheric polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Two gas/particle partitioning models, the subcooled liquid vapor pressure (P L 0 ) and the octanol-air partition coefficient (K OA ) model, were applied to each particle sizes. The regression coefficients of each fraction against the gas/particle partition coefficient (K P ) were similar for separated particles within the same sample set but differed for particles collected during different periods. Gas/particle partitioning calculated from the integral of fractions was similar to that of size-segregated particles and previously measured bulk values. Despite the different behaviors and production mechanisms of atmospheric particles of different sizes, PCDD/F partitioning of each size range was controlled by meteorological conditions such as atmospheric temperature, O 3 and UV, which reflects no source related with certain particle size ranges but mixed urban sources within this city. Our observations emphasize that when assessing environmental and health effects, the movement of PCDD/Fs in air should be considered in conjunction with particle size in addition to the bulk aerosol. - Gas/particle partitioning of atmospheric PCDD/Fs for different particle sizes reflects the impacts of emitters of different size ranges

  14. Direct determination of highly size-resolved turbulent particle fluxes with the disjunct eddy covariance method and a 12 – stage electrical low pressure impactor

    Directory of Open Access Journals (Sweden)

    A. Schmidt

    2008-12-01

    Full Text Available During summer 2007, turbulent vertical particle mass and number fluxes were measured for a period of 98 days near the city centre of Münster in north-west Germany. For this purpose, a valve controlled disjunct eddy covariance system was mounted at 65 m a.g.l. on a military radio tower. The concentration values for 11 size bins with aerodynamic diameters (D50 from 0.03 to 10 μm were measured with an electrical low pressure impactor. After comparison with other fluxes obtained from 10 Hz measurements with the classical eddy covariance method, the loss of information concerning high frequent parts of the flux could be stated as negligible. The results offer an extended insight in the turbulent atmospheric exchange of aerosol particles by highly size-resolved particle fluxes covering 11 size bins and show that the city of Münster acts as a relevant source for aerosol particles.

    Significant differences occur between the fluxes of the various particle size classes. While the total particle number flux shows a pattern which is strictly correlated to the diurnal course of the turbulence regime and the traffic intensity, the total mass flux exhibits a single minimum in the evening hours when coarse particles start to deposit.

    As a result, a mean mass deposition of about 10 mg m−2 per day was found above the urban test site, covering the aerosol size range from 40 nm to 2.0 μm. By contrast, the half-hourly total number fluxes accumulated over the lower ELPI stages range from −4.29×107 to +1.44×108 particles m−2 s−1 and are clearly dominated by the sub-micron particle fraction of the impactor stages with diameters between 40 nm and 320 nm. The averaged number fluxes of particles with diameters between 2.0 and 6.4 μm show lower turbulent dynamics during daytime and partially remarkably high negative fluxes with mean deposition velocities of 2×10−3 m

  15. Correlation between sub-micron surface roughness of iron oxide encrustations and trace element concentrations

    International Nuclear Information System (INIS)

    Fischer, Cornelius; Karius, Volker; Luettge, Andreas

    2009-01-01

    Iron oxide encrustations are formed on black slate surfaces during oxidative weathering of iron sulfide and phosphate bearing, organic matter-rich slates. Synchronously, trace elements are released during ongoing weathering. Laser ablation ICP-MS analyses of a weathered and encrusted slate showed that major portions of the V, Cu, As, Mo, Pb, Th, and U reside in the encrustation. Recently a potential relationship between several micrometer to 500 nm surface topography roughness of such encrustations and its uranium concentration was shown. Based on laser scanning microscopy measurements, the present study shows that this interrelation must be expanded to small submicron-sized half-pores with diameters between 100 nm and 500 nm. We demonstrate that the relationship is not limited to topography variations of a single encrustation in the hand-specimen scale. Surface topography and geochemical analyses of iron oxide encrustations from several locations but from the same geochemical environment and with similar weathering history showed that the concentrations of U, P, Cu, and Zn correlate inversely with the surface roughness parameter F. This parameter represents the total surface area and is - in this case - a proxy for the root-mean square surface roughness Rq. This study substantiates the environmental importance that micrometer- to submicrometer topography variations of fluid-rock interfaces govern the trapping of trace elements.

  16. Correlation between sub-micron surface roughness of iron oxide encrustations and trace element concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Cornelius, E-mail: cornelius@rice.edu [Department of Earth Science, MS-126, Rice University, 6100 Main Street, Houston, TX 77005 (United States); Geowissenschaftliches Zentrum der Universitaet Goettingen, Abt. Sedimentologie and Umweltgeologie, Goldschmidtstr. 3, D-37077 Goettingen (Germany); Karius, Volker [Geowissenschaftliches Zentrum der Universitaet Goettingen, Abt. Sedimentologie and Umweltgeologie, Goldschmidtstr. 3, D-37077 Goettingen (Germany); Luettge, Andreas [Department of Earth Science, MS-126, Rice University, 6100 Main Street, Houston, TX 77005 (United States); Department of Chemistry, Rice University, 6100 Main Street, Houston, TX 77005 (United States)

    2009-08-01

    Iron oxide encrustations are formed on black slate surfaces during oxidative weathering of iron sulfide and phosphate bearing, organic matter-rich slates. Synchronously, trace elements are released during ongoing weathering. Laser ablation ICP-MS analyses of a weathered and encrusted slate showed that major portions of the V, Cu, As, Mo, Pb, Th, and U reside in the encrustation. Recently a potential relationship between several micrometer to 500 nm surface topography roughness of such encrustations and its uranium concentration was shown. Based on laser scanning microscopy measurements, the present study shows that this interrelation must be expanded to small submicron-sized half-pores with diameters between 100 nm and 500 nm. We demonstrate that the relationship is not limited to topography variations of a single encrustation in the hand-specimen scale. Surface topography and geochemical analyses of iron oxide encrustations from several locations but from the same geochemical environment and with similar weathering history showed that the concentrations of U, P, Cu, and Zn correlate inversely with the surface roughness parameter F. This parameter represents the total surface area and is - in this case - a proxy for the root-mean square surface roughness Rq. This study substantiates the environmental importance that micrometer- to submicrometer topography variations of fluid-rock interfaces govern the trapping of trace elements.

  17. Penetration of sub-micron aerosol droplets in composite cylindrical filtration elements

    International Nuclear Information System (INIS)

    Geurts, Bernard J.; Pratte, Pascal; Stolz, Steffen; Stabbert, Regina; Poux, Valerie; Nordlund, Markus; Winkelmann, Christoph

    2011-01-01

    Advection-diffusion transport of aerosol droplets in composite cylindrical filtration elements is analyzed and compared to experimental data. The penetration, characterizing the fraction of droplets that passes through the pores of a filtration element, is quantified for a range of flow rates. The advection-diffusion transport in a laminar Poiseuille flow is treated numerically for slender pores using a finite difference approach in cylindrical coordinates. The algebraic dependence of the penetration on the Peclet number as predicted theoretically, is confirmed by experimental findings at a variety of aspect ratios of the cylindrical pores. The effective penetration associated with a composite filtration element consisting of a set of parallel cylindrical pores is derived. The overall penetration of heterogeneous composite filtration elements shows an algebraic dependence to the fourth power on the radii of the individual pores that are contained. This gives rise to strong variations in the overall penetration in cases with uneven distributions of pore sizes, highly favoring filtration by the larger pores. The overall penetration is computed for a number of basic geometries, providing a point of reference for filtration design and experimental verification.

  18. Concentration and size distribution of particles in abstracted groundwater

    NARCIS (Netherlands)

    Van Beek, C.G.E.M.; de Zwart, A.H.; Balemans, M.; Kooiman, J.W.; van Rosmalen, C.; Timmer, H.; Vandersluys, J.; Stuijfzand, P.J.

    2010-01-01

    Particle number concentrations have been counted and particle size distributions calculated in groundwater derived by abstraction wells. Both concentration and size distribution are governed by the discharge rate: the higher this rate the higher the concentration and the higher the proportion of

  19. 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.

  20. 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.

  1. Particle size dependence of biogenic secondary organic aerosol molecular composition

    Science.gov (United States)

    Tu, Peijun; Johnston, Murray V.

    2017-06-01

    Formation of secondary organic aerosol (SOA) is initiated by the oxidation of volatile organic compounds (VOCs) in the gas phase whose products subsequently partition to the particle phase. Non-volatile molecules have a negligible evaporation rate and grow particles at their condensation rate. Semi-volatile molecules have a significant evaporation rate and grow particles at a much slower rate than their condensation rate. Particle phase chemistry may enhance particle growth if it transforms partitioned semi-volatile molecules into non-volatile products. In principle, changes in molecular composition as a function of particle size allow non-volatile molecules that have condensed from the gas phase (a surface-limited process) to be distinguished from those produced by particle phase reaction (a volume-limited process). In this work, SOA was produced by β-pinene ozonolysis in a flow tube reactor. Aerosol exiting the reactor was size-selected with a differential mobility analyzer, and individual particle sizes between 35 and 110 nm in diameter were characterized by on- and offline mass spectrometry. Both the average oxygen-to-carbon (O / C) ratio and carbon oxidation state (OSc) were found to decrease with increasing particle size, while the relative signal intensity of oligomers increased with increasing particle size. These results are consistent with oligomer formation primarily in the particle phase (accretion reactions, which become more favored as the volume-to-surface-area ratio of the particle increases). Analysis of a series of polydisperse SOA samples showed similar dependencies: as the mass loading increased (and average volume-to-surface-area ratio increased), the average O / C ratio and OSc decreased, while the relative intensity of oligomer ions increased. The results illustrate the potential impact that particle phase chemistry can have on biogenic SOA formation and the particle size range where this chemistry becomes important.

  2. Particle size dependence of biogenic secondary organic aerosol molecular composition

    Directory of Open Access Journals (Sweden)

    P. Tu

    2017-06-01

    Full Text Available Formation of secondary organic aerosol (SOA is initiated by the oxidation of volatile organic compounds (VOCs in the gas phase whose products subsequently partition to the particle phase. Non-volatile molecules have a negligible evaporation rate and grow particles at their condensation rate. Semi-volatile molecules have a significant evaporation rate and grow particles at a much slower rate than their condensation rate. Particle phase chemistry may enhance particle growth if it transforms partitioned semi-volatile molecules into non-volatile products. In principle, changes in molecular composition as a function of particle size allow non-volatile molecules that have condensed from the gas phase (a surface-limited process to be distinguished from those produced by particle phase reaction (a volume-limited process. In this work, SOA was produced by β-pinene ozonolysis in a flow tube reactor. Aerosol exiting the reactor was size-selected with a differential mobility analyzer, and individual particle sizes between 35 and 110 nm in diameter were characterized by on- and offline mass spectrometry. Both the average oxygen-to-carbon (O ∕ C ratio and carbon oxidation state (OSc were found to decrease with increasing particle size, while the relative signal intensity of oligomers increased with increasing particle size. These results are consistent with oligomer formation primarily in the particle phase (accretion reactions, which become more favored as the volume-to-surface-area ratio of the particle increases. Analysis of a series of polydisperse SOA samples showed similar dependencies: as the mass loading increased (and average volume-to-surface-area ratio increased, the average O ∕ C ratio and OSc decreased, while the relative intensity of oligomer ions increased. The results illustrate the potential impact that particle phase chemistry can have on biogenic SOA formation and the particle size range where this chemistry becomes

  3. Prospects for sub-micron solid state nuclear magnetic resonance imaging with low-temperature dynamic nuclear polarization.

    Science.gov (United States)

    Thurber, Kent R; Tycko, Robert

    2010-06-14

    We evaluate the feasibility of (1)H nuclear magnetic resonance (NMR) imaging with sub-micron voxel dimensions using a combination of low temperatures and dynamic nuclear polarization (DNP). Experiments are performed on nitroxide-doped glycerol-water at 9.4 T and temperatures below 40 K, using a 30 mW tunable microwave source for DNP. With DNP at 7 K, a 0.5 microL sample yields a (1)H NMR signal-to-noise ratio of 770 in two scans with pulsed spin-lock detection and after 80 db signal attenuation. With reasonable extrapolations, we infer that (1)H NMR signals from 1 microm(3) voxel volumes should be readily detectable, and voxels as small as 0.03 microm(3) may eventually be detectable. Through homonuclear decoupling with a frequency-switched Lee-Goldburg spin echo technique, we obtain 830 Hz (1)H NMR linewidths at low temperatures, implying that pulsed field gradients equal to 0.4 G/d or less would be required during spatial encoding dimensions of an imaging sequence, where d is the resolution in each dimension.

  4. Parametric study of plasma-mediated thermoluminescence produced by Al2O3 sub-micron powders

    Science.gov (United States)

    Morávek, T.; Ambrico, P. F.; Ambrico, M.; Schiavulli, L.; Ráheľ, J.

    2017-10-01

    Sub-micron Al2O3 powders with a surface activated by dielectric barrier discharge exhibit improved performance in wet deposition of ceramic layers. In addressing the possible mechanisms responsible for the observed improvement, a comprehensive thermoluminescence (TL) study of plasma-activated powders was performed. TL offers the unique possibility of exploring the population of intrinsic electrons/holes in the charge trapping states. This study covers a wide range of experimental conditions affecting the TL of powders: treatment time, plasma working gas composition, change of discharge configuration, step-annealing of powder, exposure to laser irradiation and aging time. Deconvoluted TL spectra were followed for the changes in their relative contributions. The TL spectra of all tested gases (air, Ar, N2 and 5% He in N2) consist of the well-known main dosimetric peak at 450 K and a peak of similar magnitude at higher temperatures, centered between 700 and 800 K depending on the working gas used. N2 plasma treatment gave rise to a new specific TL peak at 510 K, which exhibited several peculiarities. Initial thermal annealing of Al2O3 powders led to its significant amplification (unlike the other peaks); the peak was insensitive to optical bleaching, and it exhibited slow gradual growth during the long-term aging test. Besides its relevance to the ceramic processing studies, a comprehensive set of data is presented that provides a useful and unconventional view on plasma-mediated material changes.

  5. Sonochemical synthesis of silica particles and their size control

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hwa-Min [Advanced Materials and Chemical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Lee, Chang-Hyun [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Kim, Bonghwan, E-mail: bhkim@cu.ac.kr [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of)

    2016-09-01

    Graphical abstract: - Highlights: • Silica particles were easily prepared by an ultrasound-assisted sol–gel method. • The particle size was controlled by the ammonium hydroxide/water molar ratio. • The size-controlled diameter of silica particles ranged from 40 to 400 nm. • The particles were formed in a relatively short reaction time. - Abstract: 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.

  6. Decomposition of Atmospheric Aerosol Phase Function by Particle Size and Morphology via Single Particle Scattering Measurements

    Science.gov (United States)

    Aptowicz, K. B.; Pan, Y.; Martin, S.; Fernandez, E.; Chang, R.; Pinnick, R. G.

    2013-12-01

    We report upon an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 micrometer to less than 1% for particles over 5 micrometer. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor.

  7. Correcting for particle size effects on plasma actuator particle image velocimetry measurements

    Science.gov (United States)

    Masati, A.; Sedwick, R. J.

    2018-01-01

    Particle image velocimetry (PIV) is often used to characterize plasma actuator flow, but particle charging effects are rarely taken into account. A parametric study was conducted to determine the effects of particle size on the velocity results of plasma actuator PIV experiments. Results showed that smaller particles more closely match air flow velocities than larger particles. The measurement uncertainty was quantified by deconvolving the particle image diameter from the correlation diameter. The true air velocity was calculated by linearly extrapolating to the zero-size particle diameter.

  8. 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.

  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. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 244-256, 2004

  10. Effect of particle size distribution on sintering of tungsten

    International Nuclear Information System (INIS)

    Patterson, B.R.; Griffin, J.A.

    1984-01-01

    To date, very little is known about the effect of the nature of the particle size distribution on sintering. It is reasonable that there should be an effect of size distribution, and theory and prior experimental work examining the effects of variations in bimodal and continuous distributions have shown marked effects on sintering. Most importantly, even with constant mean particle size, variations in distribution width, or standard deviation, have been shown to produce marked variations in microstructure and sintering rate. In the latter work, in which spherical copper powders were blended to produce lognormal distributions of constant geometric mean particle size by weight frequency, blends with larger values of geometric standard deviation, 1nσ, sintered more rapidly. The goals of the present study were to examine in more detail the effects of variations in the width of lognormal particle size distributions of tungsten powder and determine the effects of 1nσ on the microstructural evolution during sintering

  11. Distribution Of Natural Radioactivity On Soil Size Particles

    International Nuclear Information System (INIS)

    Tran Van Luyen; Trinh Hoai Vinh; Thai Khac Dinh

    2008-01-01

    This report presents a distribution of natural radioactivity on different soil size particles, taken from one soil profile. On the results shows a range from 52% to 66% of natural radioisotopes such as 238 U, 232 Th, 226 Ra and 40 K concentrated on the soil particles below 40 micrometers in diameter size. The remained of natural radioisotopes were distributed on a soil particles with higher diameter size. The study is available for soil sample collected to natural radioactive analyze by gamma and alpha spectrometer methods. (author)

  12. Particle sizing experiments with the laser Doppler velocimeter: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Giel, T.V. Jr.; Son, J.Y.

    1988-06-01

    Measurement techniques for in-situ simultaneous measurements of particle size distributions and particle velocities using the dual beam laser Doppler velocimeter (LV) were analytically and experimentally investigated. This investigation examined the different signal characteristics of the LV for determination of particle size and particle velocity, simultaneously. The different size related signal components were evaluated not only singularly but also as simultaneous measurements to determine which characteristic, or combination of characteristics, provided the best measure of particle size. The evaluation concentrated on the 0.5 to 5 ..mu..m particle size range, in which the LV light scattering characteristics are complex often non-monotonic functions of the particle size as well as functions of index of refraction, the laser light wavelength, laser intensity and polarization, and the location and response characteristics of the detector. Different components of the LV signal were considered, but analysis concentrated on Doppler phase, visibility and scatter-intensity because they show the greatest promise. These signals characteristics were initially defined analytically for numerous optical configurations over the 0.5 to 5 ..mu..m diameter range with 0.1 ..mu..m segmentation, for refractive index values from 1.0 to 3.0 with absorptive (imaginary) components varied form 0 to 1.0. Collector orientation and effective f/No., as well as fringe spacing, beam polarization and wavelength, were varied in this analytical evaluation. 18 refs., 42 figs., 5 tabs.

  13. Relationship between dioxin concentration and particle size for suspended sediment

    Energy Technology Data Exchange (ETDEWEB)

    Kitamura, K.; Sakurai, T.; Choi, J.W.; Suzuki, N.; Morita, M. [National Inst. for Environmental Studies, Tsukuba (Japan)

    2004-09-15

    The purpose of the present study was to find out how the amounts of adsorbed dioxins, i.e., polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/Fs), mono-ortho-polychlorinated biphenyls (PCBs) and non-ortho-PCBs, vary with the particle size of suspended sediment. As dioxins are hydrophobic, they tend to adsorb onto particles suspended in water, and the determination of which dioxin congeners readily dissolve in water or adsorb onto particles is central to the characterization of dioxin behavior in water/sediment systems. Presumably suspension of sediments and the size of the particles govern the transfer of dioxins to aquatic organisms. Therefore, in the present study, we investigated the relationship between the amount of dioxins and the particle-size distribution of resuspended, rather than settled, sediment.

  14. Karna Particle Size Dataset for Tables and Figures

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset contains 1) table of bulk Pb-XAS LCF results, 2) table of bulk As-XAS LCF results, 3) figure data of particle size distribution, and 4) figure data for...

  15. 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...

  16. Stabilization of amorphous calcium carbonate by controlling its particle size

    NARCIS (Netherlands)

    Nudelman, F.; Sonmezler, E.; Bomans, P.H.H.; With, de G.; Sommerdijk, N.A.J.M.

    2010-01-01

    Amorphous calcium carbonate (ACC) nanoparticles of different size are prepared using a flow system. Post-synthesis stabilization with a layer of poly[(a,ß)-DL-aspartic acid] leads to stabilization of the ACC, but only for particles

  17. WOOD STOVE EMISSIONS: PARTICLE SIZE AND CHEMICAL COMPOSITION

    Science.gov (United States)

    The report summarizes wood stove particle size and chemical composition data gathered to date. [NOTE: In 1995, EPA estimated that residential wood combustion (RWC), including fireplaces, accounted for a significant fraction of national particulate matter with aerodynamic diameter...

  18. Polybutadiene latex particle size distribution analysis utilizing a disk centrifuge

    NARCIS (Netherlands)

    Verdurmen, E.M.F.J.; Albers, J.G.; German, A.L.

    1994-01-01

    Polybutadiene (I) latexes prepd. by emulsifier-free emulsion polymn. and having particle diam. 50-300 nm for both unimodal and bimodal particles size distributions were analyzed by the line-start (LIST) method in a Brookhaven disk centrifuge photosedimentometer. A special spin fluid was designed to

  19. Effect of limestone particle size on bone quality characteristics of ...

    African Journals Online (AJOL)

    A study was conducted to determine the effect of different limestone particle sizes in layer diets on bone quality characteristics at end-of-lay hens. Calcitic limestone (360 g Ca/kg DM) that is extensively used in commercial poultry diets was obtained from a specific South African source. Limestone particles were graded as ...

  20. Particle size- and concentration-dependent separation of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Witte, Kerstin, E-mail: witte@micromod.de [University of Rostock, Institute of Physics, Albert-Einstein-Str. 23, 18059 Rostock (Germany); Micromod Partikeltechnologie GmbH, Friedrich-Barnewitz-Str. 4, 18119 Rostock (Germany); Müller, Knut; Grüttner, Cordula; Westphal, Fritz [Micromod Partikeltechnologie GmbH, Friedrich-Barnewitz-Str. 4, 18119 Rostock (Germany); Johansson, Christer [Acreo Swedish ICT AB, 40014 Göteborg (Sweden)

    2017-04-01

    Small magnetic nanoparticles with a narrow size distribution are of great interest for several biomedical applications. When the size of the particles decreases, the magnetic moment of the particles decreases. This leads to a significant increase in the separation time by several orders of magnitude. Therefore, in the present study the separation processes of bionized nanoferrites (BNF) with different sizes and concentrations were investigated with the commercial Sepmag Q system. It was found that an increasing initial particle concentration leads to a reduction of the separation time for large nanoparticles due to the higher probability of building chains. Small nanoparticles showed exactly the opposite behavior with rising particle concentration up to 0.1 mg(Fe)/ml. For higher iron concentrations the separation time remains constant and the measured Z-average decreases in the supernatant at same time intervals. At half separation time a high yield with decreasing hydrodynamic diameter of particles can be obtained using higher initial particle concentrations. - Highlights: • Size dependent separation processes of multicore nanoparticles. • Concentration dependent separation processes of multicore nanoparticles. • Increasing separation time with rising concentrations for small particles. • Large particles show typical cooperative magnetophoresis behavior.

  1. Effect of limestone particle size on egg production and eggshell ...

    African Journals Online (AJOL)

    Different limestone particle sizes had no effect on any of the tested egg production and eggshell quality parameters. These results suggested that larger particles limestone are not necessarily essential to provide sufficient Ca2+ to laying hens for egg production and eggshell quality at end-of-lay, provided that the dietary Ca ...

  2. Assessment of particle size distribution in CO 2 accidental releases

    NARCIS (Netherlands)

    Hulsbosch-Dam, C.E.C.; Spruijt, M.P.N.; Necci, A.; Cozzani, V.

    2012-01-01

    A model was developed to calculate the particle size distribution following the release of pressurised supercritical CO 2. The model combines several sub-models for the different stages of jet break-up and specifically addresses the possible formation of solid particles, which is important for CO 2

  3. SiO2/ZnO Composite Hollow Sub-Micron Fibers: Fabrication from Facile Single Capillary Electrospinning and Their Photoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Guanying Song

    2017-02-01

    Full Text Available In this work, SiO2/ZnO composite hollow sub-micron fibers were fabricated by a facile single capillary electrospinning technique followed by calcination, using tetraethyl orthosilicate (TEOS, polyvinylpyrrolidone (PVP and ZnO nanoparticles as raw materials. The characterization results of the scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FT-IR spectra indicated that the asprepared composite hollow fibers consisted of amorphous SiO2 and hexagonal wurtzite ZnO. The products revealed uniform tubular structure with outer diameters of 400–500 nm and wall thickness of 50–60 nm. The gases generated and the directional escaped mechanism was proposed to illustrate the formation of SiO2/ZnO composite hollow sub-micron fibers. Furthermore, a broad blue emission band was observed in the photoluminescence (PL of SiO2/ZnO composite hollow sub-micron fibers, exhibiting great potential applications as blue light-emitting candidate materials.

  4. Sizes of particles formed during municipal wastewater treatment.

    Science.gov (United States)

    Lech, Smoczynski; Marta, Kosobucka; Michal, Smoczynski; Harsha, Ratnaweera; Krystyna, Pieczulis-Smoczynska

    2017-02-01

    Volumetric diameters Dv and specific surface area SpS of sludge particles formed during chemical coagulation and electrocoagulation of sewage were determined. The obtained aggregate-flocs differed substantially in both Dv and SpS values. The differences in Dv and SpS values of the analyzed particles were interpreted based on theoretical models for expanding aggregates. The most uniform particles were formed under exposure to: (a) optimal and maximal doses of PIX, (b) optimal doses of PAX, (c) maximal doses of the Al electro-coagulant. The lowest PIX dose produced the least uniform particles. Sludge aggregates-particles produced under exposure to minimal doses of PIX and the Al electro-coagulant were characterized by the lowest SpS values. Sludge particles coagulated by PAX and the particles formed at higher doses of PIX and the Al electro-coagulant had higher SpS values. The particles formed at all doses of the applied coagulants and electro-coagulants were generally classified into two size ranges: the main range and the secondary range. Most particles belonged to the main size range. An increase in the percentage of colloidal hydroxide particles in sewage sludge increased SpS.

  5. A system for aerodynamically sizing ultrafine environmental radioactive particles

    International Nuclear Information System (INIS)

    Olawoyin, L.

    1995-09-01

    The unattached environmental radioactive particles/clusters, produced mainly by 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. 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.

  7. Effect of particle size on iron nanoparticle oxidation state

    International Nuclear Information System (INIS)

    Lombardo, Jeffrey J.; Lysaght, Andrew C.; Goberman, Daniel G.; Chiu, Wilson K.S.

    2012-01-01

    Selecting catalyst particles is a very important part of carbon nanotube growth, although the properties of these nanoscale particles are unclear. In this article iron nanoparticles are analyzed through the use of atomic force microscopy and x-ray photoelectron spectroscopy in order to understand how the size affects the chemical composition of nanoparticles and thus their physical structure. Initially, atomic force microscopy was used to confirm the presence of iron particles, and to determine the average size of the particles. Next an analytical model was developed to estimate particle size as a function of deposition time using inputs from atomic force microscopy measurement. X-ray photoelectron spectroscopy analysis was then performed with a focus on the spectra relating to the 2p Fe electrons to study the chemical state of the particles as a function of time. It was shown that as the size of nanoparticles decreased, the oxidation state of the particles changed due to a high proportion of atoms on the surface.

  8. Strategy for determination of an efficient Cochleate particle size.

    Science.gov (United States)

    Gil, Danay; Bracho, Gustavo; Zayas, Caridad; del Campo, Judith; Acevedo, Reinaldo; Toledo, Arturo; Lastre, Miriam; Pérez, Oliver

    2006-04-12

    Cochleate structures obtained from the outer membrane of Neisseria meningitidis serotype B have demonstrated to be high immunogenicity when administrated by intramuscular, oral or intranasal routes, and could be used as adjuvant and meningococcal nasal vaccine candidate. Due to the microparticulate nature of Cochleate it is necessary to control the particle size since it capture by cells of the immune system could be affected by this aspect. We combined optic microscopy and immunisation experiments to select the optimum particle size. Six different processes of producing Cochleate obtaining were evaluated and different mechanical stress conditions were carried out to homogenize and modulate the particles size. The more immunogenic particles were selected on the basis of the levels of specific IgA and IgG antibodies induced after intranasal immunisation in mice. The best treatment parameter for mechanical stress of the Cochleate was prolonged treatment with untrasonic low frequency waves.

  9. Dust generation in powders: Effect of particle size distribution

    Directory of Open Access Journals (Sweden)

    Chakravarty Somik

    2017-01-01

    Full Text Available This study explores the relationship between the bulk and grain-scale properties of powders and dust generation. A vortex shaker dustiness tester was used to evaluate 8 calcium carbonate test powders with median particle sizes ranging from 2μm to 136μm. Respirable aerosols released from the powder samples were characterised by their particle number and mass concentrations. All the powder samples were found to release respirable fractions of dust particles which end up decreasing with time. The variation of powder dustiness as a function of the particle size distribution was analysed for the powders, which were classified into three groups based on the fraction of particles within the respirable range. The trends we observe might be due to the interplay of several mechanisms like de-agglomeration and attrition and their relative importance.

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

    International Nuclear Information System (INIS)

    1978-01-01

    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

  11. Particle interaction of lubricated or unlubricated binary mixtures according to their particle size and densification mechanism.

    Science.gov (United States)

    Di Martino, Piera; Joiris, Etienne; Martelli, Sante

    2004-09-01

    The aim of this study is to assess an experimental approach for technological development of a direct compression formulation. A simple formula was considered composed by an active ingredient, a diluent and a lubricant. The active ingredient and diluent were selected as an example according to their typical densification mechanism: the nitrofurantoine, a fragmenting material, and the cellulose microcrystalline (Vivapur), which is a typical visco-elastic material, equally displaying good bind and disintegrant properties. For each ingredient, samples of different particle size distribution were selected. Initially, tabletability of pure materials was studied by a rotary press without magnesium stearate. Vivapur tabletability decreases with increase in particle size. The addition of magnesium stearate as lubricant decreases tabletability of Vivapur of greater particle size, while it kept unmodified that of Vivapur of lower particle size. Differences in tabletability can be related to differences in particle-particle interactions; for Vivapur of higher particle size (Vivapur 200, 102 and 101), the lower surface area develops lower surface available for bonds, while for Vivapur of lower particle size (99 and 105) the greater surface area allows high particle proximity favouring particle cohesivity. Nitrofurantoine shows great differences in compression behaviour according to its particle size distribution. Large crystals show poorer tabletability than fine crystals, further decreased by lubricant addition. The large crystals poor tabletability is due to their poor compactibility, in spite of high compressibility and plastic intrinsic deformability; in fact, in spite of the high densification tendency, the nature of the involved bonds is very weak. Nitrofurantoine samples were then mixed with Vivapurs in different proportions. Compression behaviour of binary mixes (tabletability and compressibility) was then evaluated according to diluents proportion in the mixes. The

  12. Saharan Dust Particle Size And Concentration Distribution In Central Ghana

    Science.gov (United States)

    Sunnu, A. K.

    2010-12-01

    A.K. Sunnu*, G. M. Afeti* and F. Resch+ *Department of Mechanical Engineering, Kwame Nkrumah University of Science and Technology (KNUST) Kumasi, Ghana. E-mail: albertsunnu@yahoo.com +Laboratoire Lepi, ISITV-Université du Sud Toulon-Var, 83162 La Valette cedex, France E-mail: resch@univ-tln.fr Keywords: Atmospheric aerosol; Saharan dust; Particle size distributions; Particle concentrations. Abstract The Saharan dust that is transported and deposited over many countries in the West African atmospheric environment (5°N), every year, during the months of November to March, known locally as the Harmattan season, have been studied over a 13-year period, between 1996 and 2009, using a location at Kumasi in central Ghana (6° 40'N, 1° 34'W) as the reference geographical point. The suspended Saharan dust particles were sampled by an optical particle counter, and the particle size distributions and concentrations were analysed. The counter gives the total dust loads as number of particles per unit volume of air. The optical particle counter used did not discriminate the smoke fractions (due to spontaneous bush fires during the dry season) from the Saharan dust. Within the particle size range measured (0.5 μm-25 μm.), the average inter-annual mean particle diameter, number and mass concentrations during the northern winter months of January and February were determined. The average daily number concentrations ranged from 15 particles/cm3 to 63 particles/cm3 with an average of 31 particles/cm3. The average daily mass concentrations ranged from 122 μg/m3 to 1344 μg/m3 with an average of 532 μg/m3. The measured particle concentrations outside the winter period were consistently less than 10 cm-3. The overall dust mean particle diameter, analyzed from the peak representative Harmattan periods over the 13-year period, ranged from 0.89 μm to 2.43 μm with an average of 1.5 μm ± 0.5. The particle size distributions exhibited the typical distribution pattern for

  13. Determination of the lateral size and thickness of solution-processed graphene flakes

    Science.gov (United States)

    Lin, Li-Shang; Bin-Tay, Wei; Aslam, Zabeada; Westwood, A. V. K.; Brydson, R.

    2017-09-01

    We present a method to determine the lateral size distribution of solution…processed graphene via direct image analysis techniques. Initially transmission electron microscopy (TEM) and optical microscopy (OM) were correlated and used to provide a reliable benchmark. A rapid, automated OM method was then developed to obtain the distribution from thousands of flakes, avoiding statistical uncertainties and providing high accuracy. Dynamic light scattering (DLS) was further employed to develop an in-situ method to derive the number particle size distribution (PSD) for a dispersion, with a deviation lower than 22% in the sub-micron regime. Methods for determining flake thickness are also discussed.

  14. Effect of particle size on mixing degree in dispensation.

    Science.gov (United States)

    Nakamura, Hitoshi; Yanagihara, Yoshitsugu; Sekiguchi, Hiroko; Ohtani, Michiteru; Kariya, Satoru; Uchino, Katsuyoshi; Suzuki, Hiroshi; Iga, Tatsuji

    2004-03-01

    By using lactose colored with erythrocin, we examined the effect of particle size on mixing degree during the preparation of triturations with a mortar and pestle. We used powders with different distributions of particle sizes, i.e., powder that passed through 32-mesh but was trapped on a 42-mesh sieve (32/42-mesh powder), powder that passed through a 42-mesh sieve but was trapped on a 60-mesh sieve (42/60-mesh powder), powder that passed through a 60-mesh sieve but was trapped on a 100-mesh sieve (60/100-mesh powder), and powder that passes through a 100-mesh sieve (> 100-mesh powder). The mixing degree of colored powder and non-colored powder whose distribution of particle sizes was the same as that of the colored powder was excellent. The coefficient of variation (CV) value of the mixing degree was 6.08% after 40 rotations when colored powder was mixed with non-colored powder that both passed through a 100-mesh sieve. The CV value of the mixing degree was low in the case of mixing of colored and non-colored powders with different particle size distributions. After mixing, about 50% of 42/60-mesh powder had become smaller particles, whereas the distribution of particle sizes was not influenced by the mixing of 60/100-mesh powder. It was suggested that the mixing degree is affected by distribution of particle sizes. It may be important to determine the mixing degrees for drugs with narrow therapeutic ranges.

  15. Selection Of Suitable Particle Size And Particle Ratio For Japanese Cucumber Cucumis Sativus L. Plants

    Directory of Open Access Journals (Sweden)

    Galahitigama GAH

    2015-08-01

    Full Text Available This study was conducted to select the best particle size of coco peat for cucumber nurseries as well as best particle ratio for optimum plant growth and development of cucumber. The experiment was carried out in International Foodstuff Company and Faculty of Agriculture University of Ruhuna Sri Lanka during 2015 to 2016. Under experiment one three types of different particle sizes were used namely fine amp88040.5mm T2 medium 3mm-0.5mm T3 and coarse 4mm T4 with normal coco peat T1 as treatments. Complete Randomized Design CRD used as experimental design with five replicates. Germination percentage number of leaves per seedling seedling height in frequent day intervals was taken as growth parameters. Analysis of variance procedure was applied to analyze the data at 5 probability level. The results revealed that medium size particle media sieve size 0.5mm -3mm of coco peat was the best particle size for cucumber nursery practice when considered the physical and chemical properties of medium particles of coco peat. In the experiment of selecting of suitable particle ratio for cucumber plants the compressed mixture of coco peat particles that contain 70 ww unsieved coco peat 20 ww coarse particles and 10 ww coconut husk chips 5 12mm has given best results for growth performances compared to other treatments and cucumber grown in this mixture has shown maximum growth and yield performances.

  16. Influence of particle size distributions on magnetorheological fluid performances

    International Nuclear Information System (INIS)

    Chiriac, H; Stoian, G

    2010-01-01

    In this paper we investigate the influence that size distributions of the magnetic particles might have on the magnetorheological fluid performances. In our study, several size distributions have been tailored first by sieving a micrometric Fe powder in order to obtain narrow distribution powders and then by recomposing the new size distributions (different from Gaussian). We used spherical Fe particles (mesh -325) commercially available. The powder was sieved by means of a sieve shaker using a series of sieves with the following mesh size: 20, 32, 40, 50, 63, 80 micrometers. All magnetic powders were characterized through Vibrating Sample Magnetometer (VSM) measurements, particle size analysis and also Scanning Electron Microscope (SEM) images were taken. Magnetorheological (MR) fluids based on the resulted magnetic powders were prepared and studied by means of a rheometer with a magnetorheological module. The MR fluids were measured in magnetic field and in zero magnetic field as well. As we noticed in our previous experiments particles size distribution can also influence the MR fluids performances.

  17. Effects of emulsion droplet sizes on the crystallisation of milk fat.

    Science.gov (United States)

    Truong, Tuyen; Bansal, Nidhi; Sharma, Ranjan; Palmer, Martin; Bhandari, Bhesh

    2014-02-15

    The crystallisation properties of milk fat emulsions containing dairy-based ingredients as functions of emulsion droplet size, cooling rate, and emulsifier type were investigated using a differential scanning calorimeter (DSC). Anhydrous milk fat and its fractions (stearin and olein) were emulsified with whey protein concentrate, sodium caseinate, and Tween80 by homogenisation to produce emulsions in various size ranges (0.13-3.10 μm). Particle size, cooling rate, and types of emulsifier all had an influence on the crystallisation properties of fat in the emulsions. In general, the crystallisation temperature of emulsified fats decreased with decreasing average droplet size and was of an exponent function of size, indicating that the influence of particle size on crystallisation temperature is more pronounced in the sub-micron range. This particle size effect was also verified by electron microscopy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Photometric imaging in particle size measurement and surface visualization.

    Science.gov (United States)

    Sandler, Niklas

    2011-09-30

    The aim of this paper is to give an insight into photometric particle sizing approaches, which differ from the typical particle size measurement of dispersed particles. These approaches can often be advantageous especially for samples that are moist or cohesive, when dispersion of particles is difficult or sometimes impossible. The main focus of this paper is in the use of photometric stereo imaging. The technique allows the reconstruction of three-dimensional images of objects using multiple light sources in illumination. The use of photometric techniques is demonstrated in at-line measurement of granules and on-line measurement during granulation and dry milling. Also, surface visualization and roughness measurements are briefly discussed. Copyright © 2010 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

    Fajgelj, A.; Zeisler, R.; Benesch, T.; Dekner, R.

    1994-01-01

    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)

  20. Using sub-micron silver-nanoparticle based films to counter biofilm formation by Gram-negative bacteria

    Science.gov (United States)

    Gillett, A. R.; Baxter, S. N.; Hodgson, S. D.; Smith, G. C.; Thomas, P. J.

    2018-06-01

    Composite films comprised of silver nanoparticles (AgNPs) grown using a low-cost straightforward chemical bath based method have been deposited on glass microscope slides to investigate their potential as a sacrificial antibacterial coating. The as-deposited films have been characterised using scanning electron microscopy (SEM) and optical profilometry. These suggested that the films were relatively uniform in coverage. Chemical composition of the AgNP films has been studied by using X-ray photoelectron spectroscopy (XPS). The XPS analysis indicated that the Ag was in a metallic form able to sustain plasmon behaviour, and that low levels of residual nanoparticle precursors were present. Particle size was characterised using transmission electron microscopy (TEM) which showed an average particle size of 10.6 nm. The effectiveness of the films as an antibacterial coating was tested against Escherichia coli. The AgNP film was determined to be effective in the killing of E. coli cells over a 24 h period when compared to equivalent samples that contained no silver. Of particular note was that only minimal bacterial growth was detected over the first 12 h of testing, up to 78.6 times less than the control samples, suggesting the film is very efficient at slowing initial biofilm formation. The use of AgNP based films that have been synthesised using a novel low-cost, low-temperature and highly upscalable method is demonstrated as a promising solution for the deployment of silver as an effective sacrifical antimicrobial coating to counter the formation of potentially hazardous Gram negative biofilms.

  1. 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.

  2. Inhalation risk and particle size in dust and mist

    Energy Technology Data Exchange (ETDEWEB)

    Davies, C N

    1949-01-01

    This paper presents a critical overview of particle uptake and retention from literature through 1949. Particles > 6-..mu..m are retained in nose, or by secondary bronchi with mouth breathing. Few > 2-..mu..m particles are exhaled, trapped mostly in bronchioles (some by alveoli) by sedimentation. Maximal deposition is 0.4- to 0.8-..mu..m size in bronchioles and alveoli. Minimim retention is at 0.1 to 0.15 ..mu..m; approx. 80% are exhaled. Brownian settling of smaller particles in alveoli occurs. Particles of low density penetrate farther. Slow breathing enhances retention. Soluble toxins may be absorbed at any point along respiratory tract, so deep penetration percentage is moot in most cases.

  3. High-resolution extraction of particle size via Fourier Ptychography

    Science.gov (United States)

    Li, Shengfu; Zhao, Yu; Chen, Guanghua; Luo, Zhenxiong; Ye, Yan

    2017-11-01

    This paper proposes a method which can extract the particle size information with a resolution beyond λ/NA. This is achieved by applying Fourier Ptychographic (FP) ideas to the present problem. In a typical FP imaging platform, a 2D LED array is used as light sources for angle-varied illuminations, a series of low-resolution images was taken by a full sequential scan of the array of LEDs. Here, we demonstrate the particle size information is extracted by turning on each single LED on a circle. The simulated results show that the proposed method can reduce the total number of images, without loss of reliability in the results.

  4. 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.

  5. 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.

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

    International Nuclear Information System (INIS)

    Leonard, Stephen S.; Castranova, Vince; Chen, Bean T.; Schwegler-Berry, Diane; Hoover, Mark; Piacitelli, Chris; Gaughan, Denise M.

    2007-01-01

    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 H 2 O 2 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

  7. The influences of ambient particle composition and size on particle infiltration in Los Angeles, CA, residences.

    Science.gov (United States)

    Sarnat, Stefanie Ebelt; Coull, Brent A; Ruiz, Pablo A; Koutrakis, Petros; Suh, Helen H

    2006-02-01

    Particle infiltration is a key determinant of the indoor concentrations of ambient particles. Few studies have examined the influence of particle composition on infiltration, particularly in areas with high concentrations of volatile particles, such as ammonium nitrate (NH4NO3). A comprehensive indoor monitoring study was conducted in 17 Los Angeles-area homes. As part of this study, indoor/outdoor concentration ratios during overnight (nonindoor source) periods were used to estimate the fraction of ambient particles remaining airborne indoors, or the particle infiltration factor (FINF), for fine particles (PM2.5), its nonvolatile (i.e., black carbon [BC]) and volatile (i.e., nitrate [NO3-]) components, and particle sizes ranging between 0.02 and 10 microm. FINF was highest for BC (median = 0.84) and lowest for NO3- (median = 0.18). The low FINF for NO3- was likely because of volatilization of NO3- particles once indoors, in addition to depositional losses upon building entry. The FINF for PM2.5 (median = 0.48) fell between those for BC and NO3-, reflecting the contributions of both particle components to PM25. FINF varied with particle size, air-exchange rate, and outdoor NO3- concentrations. The FINF for particles between 0.7 and 2 microm in size was considerably lower during periods of high as compared with low outdoor NO3- concentrations, suggesting that outdoor NO3- particles were of this size. This study demonstrates that infiltration of PM2.5 varies by particle component and is lowest for volatile species, such as NH4NO3. Our results suggest that volatile particle components may influence the ability for outdoor PM concentrations to represent indoor and, thus, personal exposures to particles of ambient origin, because volatilization of these particles causes the composition of PM2.5 to differ indoors and outdoors. Consequently, particle composition likely influences observed epidemiologic relationships based on outdoor PM concentrations, especially in areas

  8. Particle size, magnetic field, and blood velocity effects on particle retention in magnetic drug targeting.

    Science.gov (United States)

    Cherry, Erica M; Maxim, Peter G; Eaton, John K

    2010-01-01

    A physics-based model of a general magnetic drug targeting (MDT) system was developed with the goal of realizing the practical limitations of MDT when electromagnets are the source of the magnetic field. The simulation tracks magnetic particles subject to gravity, drag force, magnetic force, and hydrodynamic lift in specified flow fields and external magnetic field distributions. A model problem was analyzed to determine the effect of drug particle size, blood flow velocity, and magnetic field gradient strength on efficiency in holding particles stationary in a laminar Poiseuille flow modeling blood flow in a medium-sized artery. It was found that particle retention rate increased with increasing particle diameter and magnetic field gradient strength and decreased with increasing bulk flow velocity. The results suggest that MDT systems with electromagnets are unsuitable for use in small arteries because it is difficult to control particles smaller than about 20 microm in diameter.

  9. Automatic particle-size analysis of HTGR nuclear fuel microspheres

    International Nuclear Information System (INIS)

    Mack, J.E.

    1977-01-01

    An automatic particle-size analyzer (PSA) has been developed at ORNL for measuring and counting samples of nuclear fuel microspheres in the diameter range of 300 to 1000 μm at rates in excess of 2000 particles per minute, requiring no sample preparation. A light blockage technique is used in conjunction with a particle singularizer. Each particle in the sample is sized, and the information is accumulated by a multi-channel pulse height analyzer. The data are then transferred automatically to a computer for calculation of mean diameter, standard deviation, kurtosis, and skewness of the distribution. Entering the sample weight and pre-coating data permits calculation of particle density and the mean coating thickness and density. Following this nondestructive analysis, the sample is collected and returned to the process line or used for further analysis. The device has potential as an on-line quality control device in processes dealing with spherical or near-spherical particles where rapid analysis is required for process control

  10. Evolution of the sedimentation technique for particle size distribution analysis

    International Nuclear Information System (INIS)

    Maley, R.

    1998-01-01

    After an introduction on the significance of particle size measurements, sedimentation methods are described, with emphasis on the evolution of the gravitational approach. The gravitational technique based on mass determination by X-ray adsorption allows fast analysis by automation and easy data handling, in addition to providing the accuracy required by quality control and research applications [it

  11. Preparation of leucite powders with controlled particle size distribution

    Czech Academy of Sciences Publication Activity Database

    Novotná, Martina; Kloužková, A.; Maixner, J.; Šatava, Vladimír

    2005-01-01

    Roč. 49, č. 4 (2005), s. 252-258 ISSN 0862-5468 R&D Projects: GA ČR GA104/03/0031 Institutional research plan: CEZ:AV0Z40320502 Keywords : leucite * preparation * particle size distribution Subject RIV: CA - Inorganic Chemistry Impact factor: 0.463, year: 2005

  12. Particle size distribution of UO sub 2 aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Raghunath, B. (Radiation Safety Systems Div., BARC, Bombay (India)); Ramachandran, R.; Majumdar, S. (Radiometallurgy Div., BARC, Bombay (India))

    1991-12-01

    The Anderson cascade impactor has been used to determine the activity mean aerodynamic diameter and the particle size distribution of UO{sub 2} powders dispersed in the form of stable aerosols in an air medium. The UO{sub 2} powders obtained by the calcination of ammonium uranyl carbonate (AUC) and ammonium diuranate (ADU) precipitates have been used. (orig./MM).

  13. Effects of Particle Size Distribution on Bioremediation of Crude Oil ...

    African Journals Online (AJOL)

    Bioremediation has been proven to be the most effective method of cleaning up oil contaminated soils through the application of nutrients and microorganism. ... The parameters examined were: moisture content, particle size distribution, total hydrocarbon content, soil pH, available nitrogen, available phosphorus, total ...

  14. 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...

  15. Estimation of particle size distribution of nanoparticles from electrical ...

    Indian Academy of Sciences (India)

    ... blockade (CB) phenomena of electrical conduction through atiny nanoparticle. Considering the ZnO nanocomposites to be spherical, Coulomb-blockade model of quantum dot isapplied here. The size distribution of particle is estimated from that model and compared with the results obtainedfrom AFM and XRD analyses.

  16. How does particle size influence caking in lactose powder?

    DEFF Research Database (Denmark)

    Carpin, Melanie Anne; Bertelsen, H.; Dalberg, A.

    2017-01-01

    Particle size distribution (PSD) is known to influence product properties such as flowability and compressibility. When producing crystalline lactose, different steps can affect the PSD of the final powder. The aim of this study was to investigate the influence of PSD on caking and the mechanisms...

  17. Particle size distribution of selected electronic nicotine delivery system products.

    Science.gov (United States)

    Oldham, Michael J; Zhang, Jingjie; Rusyniak, Mark J; Kane, David B; Gardner, William P

    2018-03-01

    Dosimetry models can be used to predict the dose of inhaled material, but they require several parameters including particle size distribution. The reported particle size distributions for aerosols from electronic nicotine delivery system (ENDS) products vary widely and don't always identify a specific product. A low-flow cascade impactor was used to determine the particle size distribution [mass median aerodynamic diameter (MMAD); geometric standard deviation (GSD)] from 20 different cartridge based ENDS products. To assess losses and vapor phase amount, collection efficiency of the system was measured by comparing the collected mass in the impactor to the difference in ENDS product mass. The levels of nicotine, glycerin, propylene glycol, water, and menthol in the formulations of each product were also measured. Regardless of the ENDS product formulation, the MMAD of all tested products was similar and ranged from 0.9 to 1.2 μm with a GSD ranging from 1.7 to 2.2. There was no consistent pattern of change in the MMAD and GSD as a function of number of puffs (cartridge life). The collection efficiency indicated that 9%-26% of the generated mass was deposited in the collection system or was in the vapor phase. The particle size distribution data are suitable for use in aerosol dosimetry programs. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Synthesis of micro-sized polystyrene magnetic particles

    International Nuclear Information System (INIS)

    Neves, Juliete S.; Suarez, Paulo A.Z.; Umpierre, Alexandre P.; Machado, Fabricio; Souza Junior, Fernando G. de

    2011-01-01

    The present work illustrates the synthesis of spherical and micro-sized polystyrene magnetic particles by using a water-based suspension polymerization process to incorporate in situ surface modified superparamagnetic Fe 3 O 4 nanoparticles. The crystallite size of Fe 3 O 4 was determined to be equal to 7.7 nm, based on Scherrer's equation and XRD measurement. According to EDX analyses, Fe 3 O 4 / polystyrene nanocomposites particles show strong characteristic peaks Kα and Kβ of iron at the interval from 6.38 KeV to 7.04 KeV with an amount of iron in the samples equal to 98 %, indicating that the inorganic material dispersed in the polystyrene matrix is essentially Fe in the form of iron oxide (Fe 3 O 4 ). The obtained polymeric materials presented good magnetic behavior, indicating that the modified Fe 3 O 4 nanoparticles were successfully dispersed in the polystyrene particles. (author)

  19. Aerosol spectral optical depths and size characteristics at a coastal industriallocation in India - effect of synoptic and mesoscale weather

    Directory of Open Access Journals (Sweden)

    K. Niranjan

    2004-06-01

    Full Text Available The aerosol spectral optical depths at ten discrete channels in the visible and near IR bands, obtained from a ground-based passive multi-wavelength solar radiometer at a coastal industrial location, Visakhapatnam, on the east coast of India, are used to study the response of the aerosol optical properties and size distributions to the changes in atmospheric humidity, wind speed and direction. It is observed that during high humidity conditions, the spectral optical depths show about 30% higher growth factors, and the size distributions show the generation of a typical new mode around 0.4 microns. The surface wind speed and direction also indicate the formation of new particles when the humid marine air mass interacts with the industrial air mass. This is interpreted in terms of new particle formation and subsequent particle growth by condensation and self-coagulation. The results obtained on the surface-size segregated aerosol mass distribution from a co-located Quartz Crystal Microbalance during different humidity conditions also show a large mass increase in the sub-micron size range with an increase in atmospheric humidity, indicating new particle formation at the sub-micron size range.

  20. Size-resolved particle emission factors for individual ships

    Science.gov (United States)

    Jonsson, Åsa M.; Westerlund, Jonathan; Hallquist, Mattias

    2011-07-01

    In these experiments size-resolved emission factors for particle number (EFPN) and mass (EFPM) have been determined for 734 individual ship passages for real-world dilution. The method used is an extractive sampling method of the passing ship plumes where particle number/mass and CO2 were measured with high time resolution (1 Hz). The measurements were conducted on a small island located in the entrance to the port of Gothenburg (N57.6849, E11.838), the largest harbor in Scandinavia. This is an emission control area (ECA) and in close vicinity to populated areas. The average EFPN and EFPM were 2.55 ± 0.11 × 1016 (kg fuel)-1 and 2050 ± 110 mg (kg fuel)-1, respectively. The determined EF for ships with multiple passages showed a great reproducibility. Size-resolved EFPN were peaking at small particle sizes ˜35 nm. Smaller particle sizes and hence less mass were observed by a gas turbine equipped ship compared to diesel engine equipped ships. On average 36 to 46% of the emitted particles by number were non-volatile and 24% by mass (EFPN 1.16 ± 0.19 × 1016 [kg fuel]-1 and EFPM 488 ± 73 mg [kg fuel]-1, respectively). This study shows a great potential to gain large data-sets regarding ship emission determining parameters that can improve current dispersion modeling for health assessments on local and regional scales. The global contributions of total and non-volatile particle mass from shipping using this extensive data-set from an ECA were estimated to be at least 0.80 Tgy-1 and 0.19 Tgy-1.

  1. Optimization of particle trapping and patterning via photovoltaic tweezers: role of light modulation and particle size

    International Nuclear Information System (INIS)

    Matarrubia, J; García-Cabañes, A; Plaza, J L; Agulló-López, F; Carrascosa, M

    2014-01-01

    The role of light modulation m and particle size on the morphology and spatial resolution of nano-particle patterns obtained by photovoltaic tweezers on Fe : LiNbO 3 has been investigated. The impact of m when using spherical as well as non-spherical (anisotropic) nano-particles deposited on the sample surface has been elucidated. Light modulation is a key parameter determining the particle profile contrast that is optimum for spherical particles and high-m values (m ∼ 1). The minimum particle periodicities reachable are also investigated obtaining periodic patterns up to 3.5 µm. This is a value at least one order of magnitude shorter than those obtained in previous reported experiments. Results are successfully explained and discussed in light of the previous reported models for photorefraction including nonlinear carrier transport and dielectrophoretic trapping. From the results, a number of rules for particle patterning optimization are derived. (paper)

  2. Diffusion of Finite-Size Particles in Confined Geometries

    KAUST Repository

    Bruna, Maria; Chapman, S. Jonathan

    2013-01-01

    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.

  3. Determination of particle size distributions from acoustic wave propagation measurements

    International Nuclear Information System (INIS)

    Spelt, P.D.; Norato, M.A.; Sangani, A.S.; Tavlarides, L.L.

    1999-01-01

    The wave equations for the interior and exterior of the particles are ensemble averaged and combined with an analysis by Allegra and Hawley [J. Acoust. Soc. Am. 51, 1545 (1972)] for the interaction of a single particle with the incident wave to determine the phase speed and attenuation of sound waves propagating through dilute slurries. The theory is shown to compare very well with the measured attenuation. The inverse problem, i.e., the problem of determining the particle size distribution given the attenuation as a function of frequency, is examined using regularization techniques that have been successful for bubbly liquids. It is shown that, unlike the bubbly liquids, the success of solving the inverse problem is limited since it depends strongly on the nature of particles and the frequency range used in inverse calculations. copyright 1999 American Institute of Physics

  4. 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 ...

  5. Particle Transport and Size Sorting in Bubble Microstreaming Flow

    Science.gov (United States)

    Thameem, Raqeeb; Rallabandi, Bhargav; Wang, Cheng; Hilgenfeldt, Sascha

    2014-11-01

    Ultrasonic driving of sessile semicylindrical bubbles results in powerful steady streaming flows that are robust over a wide range of driving frequencies. In a microchannel, this flow field pattern can be fine-tuned to achieve size-sensitive sorting and trapping of particles at scales much smaller than the bubble itself; the sorting mechanism has been successfully described based on simple geometrical considerations. We investigate the sorting process in more detail, both experimentally (using new parameter variations that allow greater control over the sorting) and theoretically (incorporating the device geometry as well as the superimposed channel flow into an asymptotic theory). This results in optimized criteria for size sorting and a theoretical description that closely matches the particle behavior close to the bubble, the crucial region for size sorting.

  6. Effect of particle size on the glass transition.

    Science.gov (United States)

    Larsen, Ryan J; Zukoski, Charles F

    2011-05-01

    The glass transition temperature of a broad class of molecules is shown to depend on molecular size. This dependency results from the size dependence of the pair potential. A generalized equation of state is used to estimate how the volume fraction at the glass transition depends on the size of the molecule, for rigid molecule glass-formers. The model shows that at a given pressure and temperature there is a size-induced glass transition: For molecules larger than a critical size, the volume fraction required to support the effective pressure due to particle attractions is above that which characterizes the glassy state. This observation establishes the boundary between nanoparticles, which exist in liquid form only as dispersions in low molecular weight solvents and large molecules which form liquids that have viscosities below those characterized by the glassy state.

  7. 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

  8. Change of particle size distribution during Brownian coagulation

    International Nuclear Information System (INIS)

    Lee, K.W.

    1984-01-01

    Change in particle size distribution due to Brownian coagulation in the continuum regime has been stuied analytically. A simple analytic solution for the size distribution of an initially lognormal distribution is obtained based on the assumption that the size distribution during the coagulation process attains or can, at least, be represented by a time dependent lognormal function. The results are found to be in a form that corrects Smoluchowski's solution for both polydispersity and size-dependent kernel. It is further shown that regardless of whether the initial distribution is narrow or broad, the spread of the distribution is characterized by approaching a fixed value of the geometric standard deviation. This result has been compared with the self-preserving distribution obtained by similarity theory. (Author)

  9. Size-dependent nonlocal effects in plasmonic semiconductor particles

    DEFF Research Database (Denmark)

    Maack, Johan Rosenkrantz; Mortensen, N. Asger; Wubs, Martijn

    2017-01-01

    Localized surface plasmons (LSP) in semiconductor particles are expected to exhibit spatial nonlocal response effects as the geometry enters the nanometer scale. To investigate these nonlocal effects, we apply the hydrodynamic model to nanospheres of two different semiconductor materials: intrinsic...... InSb and n-doped GaAs. Our results show that the semiconductors indeed display nonlocal effects, and that these effects are even more pronounced than in metals. In a 150 nm InSb particle at 300 K, the LSP frequency is blueshifted 35%, which is orders of magnitude larger than the blueshift in a metal...... particle of the same size. This property, together with their tunability, makes semiconductors a promising platform for experiments in nonlocal effects. Copyright (C)EPLA, 2017...

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    feedstuffs with a decrease of 74 % between 24 h and 288 h in situ rumen incubation. Together with the highest mass proportion (20 %) of particles in the critical zone for escape (smaller than 0.005 mm2 in area) for late cut grass silage after 288 h in situ rumen incubation, this imposes a risk for particle...... 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 grinding of concentrates, II) neutral detergent soluble (NDS) extraction, III) machine-washing and NDS extraction, IV) 24 h rumen incubation, machine-washing and NDS extraction, and V) 288 h rumen incubation, machine-washing and NDS extraction. Degradation profiles for potentially degradable NDF were...

  11. Size-exclusion chromatography using core-shell particles.

    Science.gov (United States)

    Pirok, Bob W J; Breuer, Pascal; Hoppe, Serafine J M; Chitty, Mike; Welch, Emmet; Farkas, Tivadar; van der Wal, Sjoerd; Peters, Ron; Schoenmakers, Peter J

    2017-02-24

    Size-exclusion chromatography (SEC) is an indispensable technique for the separation of high-molecular-weight analytes and for determining molar-mass distributions. The potential application of SEC as second-dimension separation in comprehensive two-dimensional liquid chromatography demands very short analysis times. Liquid chromatography benefits from the advent of highly efficient core-shell packing materials, but because of the reduced total pore volume these materials have so far not been explored in SEC. The feasibility of using core-shell particles in SEC has been investigated and contemporary core-shell materials were compared with conventional packing materials for SEC. Columns packed with very small core-shell particles showed excellent resolution in specific molar-mass ranges, depending on the pore size. The analysis times were about an order of magnitude shorter than what could be achieved using conventional SEC columns. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Studies of particle drying using non-invasive Raman spectrometry and particle size analysis.

    Science.gov (United States)

    Hamilton, Peter; Littlejohn, David; Nordon, Alison; Sefcik, Jan; Slavin, Paul; Dallin, Paul; Andrews, John

    2011-05-21

    The evaporation of methanol from needle-shaped particles of cellobiose octaacetate (COA) has been studied directly in a jacketed vacuum drier using in situ measurements by Raman spectrometry. A design of experiments (DoE) approach was used to investigate the effects of three parameters (method of agitation, % solvent loss on drying and jacket temperature), with the intention of minimising the drying time and extent of particle attrition. Drying curves based on Raman signals for methanol and COA in the spectra of the wet particles indicated the end of drying and revealed three stages in the drying process that could be used to monitor the progress of solvent removal in real time. Off-line particle size measurements based on laser diffraction were made to obtain information on the extent of attrition, to compare with the trends revealed by the Raman drying curves. The study demonstrated that non-invasive Raman spectrometry can be used to study the progress of drying during agitation of particles in a vacuum drier, allowing optimisation of operating conditions to minimise attrition and reduce drying times. Although a correlation between particle size and off-line Raman measurements of COA was demonstrated, it was not possible to derive equivalent information from the in situ Raman spectra owing to the greater effects of particle motion or bulk density variations of the particles in the drier.

  13. Light absorption by coated nano-sized carbonaceous particles

    Science.gov (United States)

    Gangl, Martin; Kocifaj, Miroslav; Videen, Gorden; Horvath, Helmuth

    The optical properties of strongly absorbing soot particles coated by transparent material are investigated experimentally and described by several modeling approaches. Soot is produced by spark discharge and passed through a Sinclair-La Mer generator where non-absorbing carnauba wax is condensed onto it to obtain internal soot-wax mixtures in a controlled way. Measurements of the extinction and volume scattering coefficient show an amplification of absorption by a factor of approximately 1.8. This behavior was described by different approaches of internally mixed materials for the modal diameters of the measured size distributions: concentric-sphere model, effective medium approximations and heterogeneous ellipsoids. The concentric-sphere model describes the absorption increase quantitatively; and hence, it is chosen to be applied to the entire particle population in the size distribution. The growth of the soot particles by condensing wax is described by a simplified growth model to estimate the different contributions of several soot particle diameters to the overall absorption cross-section.

  14. Mass size distribution of particle-bound water

    Science.gov (United States)

    Canepari, S.; Simonetti, G.; Perrino, C.

    2017-09-01

    The thermal-ramp Karl-Fisher method (tr-KF) for the determination of PM-bound water has been applied to size-segregated PM samples collected in areas subjected to different environmental conditions (protracted atmospheric stability, desert dust intrusion, urban atmosphere). This method, based on the use of a thermal ramp for the desorption of water from PM samples and the subsequent analysis by the coulometric KF technique, had been previously shown to differentiate water contributes retained with different strength and associated to different chemical components in the atmospheric aerosol. The application of the method to size-segregated samples has revealed that water showed a typical mass size distribution in each one of the three environmental situations that were taken into consideration. A very similar size distribution was shown by the chemical PM components that prevailed during each event: ammonium nitrate in the case of atmospheric stability, crustal species in the case of desert dust, road-dust components in the case of urban sites. The shape of the tr-KF curve varied according to the size of the collected particles. Considering the size ranges that better characterize the event (fine fraction for atmospheric stability, coarse fraction for dust intrusion, bi-modal distribution for urban dust), this shape is coherent with the typical tr-KF shape shown by water bound to the chemical species that predominate in the same PM size range (ammonium nitrate, crustal species, secondary/combustion species - road dust components).

  15. Fabrication and size control of Ag nano particles

    International Nuclear Information System (INIS)

    Farbod, M.; Batvandi, M. R.

    2012-01-01

    The objective of this research was to fabricate Ag nanoparticles and control their sizes. Colloidal Ag nanoparticles with particle size of 30 nm were prepared by dissolving AgNO 3 in ethanol and through the chemical reduction of Ag + in alcohol solution. To control the nanoparticle size, different samples were fabricated by changing the AgNO 3 and stabilizer concentrations and the effects of different factors on the shape and size of nanoparticles were investigated. The samples were characterized using Scanning Electron Microscopy and EDX analysis. The results showed that by increasing the AgNO 3 concentration, the average size of nanoparticles increases and nanoparticles lose their spherical shape. Also, we found that by using the stabilizer, it is possible to produce stable nanoparticles but increasing the stabilizer concentration caused an increase in size of nanoparticles. Fabrication of nanoparticles without using stabilizer was achieved but the results showed the nanoparticles size had a growth of 125 nm/h in the alcoholic media.

  16. 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...

  17. FIELD COMPARISONS OF DUAL SMPS-APS SYSTEMS TO MEASURE INDOOR-OUTDOOR PARTICLE SIZE DISTRIBUTIONS

    Science.gov (United States)

    Simultaneous measurements of particle size distributions across multiple locations can provide critical information to accurately assess human exposure to particles. These data are very useful to describe indoor-outdoor particle relationships, outdoor particle penetration thro...

  18. Size and Velocity Distributions of Particles and Droplets in Spray Combustion Systems.

    Science.gov (United States)

    1984-11-01

    34Particle Sizing by Optical , Nonimaging Techniques," Liquid Particle Size _Mjur-mentTechnjgjwi, ASTM publications STP848, ed. by J. MI. Tishkoff, R. D... Optical Nonimaging predictions do not account for nonideal lens effects. Techniques," in Liquid Particle Size Measurement Techniques, J.M.Tishkoff, ed...4S E. Dan Hirleman’ Particle Sizing by Optical , Nonimaging Techniques REFERENCE: Hieleman, E. D., "Particle Sizing by Optical , Nonimaging Tech- niques

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

    International Nuclear Information System (INIS)

    Yuan Yuan; Yi Hongliang; Shuai Yong; Wang Fuqiang; Tan Heping

    2010-01-01

    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.

  20. Particle size and radionuclide levels in some west Cumbrian soils

    International Nuclear Information System (INIS)

    Livens, F.R.

    1988-01-01

    Four west Cumbrian soils of contrasting types, together with an estuarine silt sample, were separated into different particle size fractions by a combination of sieving and settling techniques. These sub-samples were analysed by quantitative gamma-ray spectrometry for several nuclides, principally 137 Cs, 106 Ru and 241 Am, followed by chemical separation and alpha spectrometric determination of 238,239,240 Pu. A simple empirical method of correction for differing sample sizes, and hence counting geometries, was developed for gamma spectrometry and found to give good results. The radionuclides were concentrated into the finer size fractions, with clay-sized ( 137 Cs from 3 to 35 times. The enhancement was greatest for all radionuclides in a sandy soil with a very low clay content (0.2% by weight) and it was found that, as the abundance of fine particles increased, so the concentration effect decreased. No evidence was found for a simple relationship between organic content and radionuclide activity, although the organic matter does have some effect. 17 refs.; 3 figs.; 6 tabs

  1. [Ultrafine particle number concentration and size distribution of vehicle exhaust ultrafine particles].

    Science.gov (United States)

    Lu, Ye-qiang; Chen, Qiu-fang; Sun, Zai; Cai, Zhi-liang; Yang, Wen-jun

    2014-09-01

    Ultrafine particle (UFP) number concentrations obtained from three different vehicles were measured using fast mobility particle sizer (FMPS) and automobile exhaust gas analyzer. UFP number concentration and size distribution were studied at different idle driving speeds. The results showed that at a low idle speed of 800 rmin-1 , the emission particle number concentration was the lowest and showed a increasing trend with the increase of idle speed. The majority of exhaust particles were in Nuclear mode and Aitken mode. The peak sizes were dominated by 10 nm and 50 nm. Particle number concentration showed a significantly sharp increase during the vehicle acceleration process, and was then kept stable when the speed was stable. In the range of 0. 4 m axial distance from the end of the exhaust pipe, the particle number concentration decayed rapidly after dilution, but it was not obvious in the range of 0. 4-1 m. The number concentration was larger than the background concentration. Concentration of exhaust emissions such as CO, HC and NO showed a reducing trend with the increase of idle speed,which was in contrast to the emission trend of particle number concentration.

  2. Two size-selective mechanisms specifically trap bacteria-sized food particles in Caenorhabditis elegans.

    Science.gov (United States)

    Fang-Yen, Christopher; Avery, Leon; Samuel, Aravinthan D T

    2009-11-24

    Caenorhabditis elegans is a filter feeder: it draws bacteria suspended in liquid into its pharynx, traps the bacteria, and ejects the liquid. How pharyngeal pumping simultaneously transports and filters food particles has been poorly understood. Here, we use high-speed video microscopy to define the detailed workings of pharyngeal mechanics. The buccal cavity and metastomal flaps regulate the flow of dense bacterial suspensions and exclude excessively large particles from entering the pharynx. A complex sequence of contractions and relaxations transports food particles in two successive trap stages before passage into the terminal bulb and intestine. Filtering occurs at each trap as bacteria are concentrated in the central lumen while fluids are expelled radially through three apical channels. Experiments with microspheres show that the C. elegans pharynx, in combination with the buccal cavity, is tuned to specifically catch and transport particles of a size range corresponding to most soil bacteria.

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

    International Nuclear Information System (INIS)

    Siddique, M.; Butt, N.M.

    2012-01-01

    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.)

  4. Particle size distributions of radioactive aerosols measured in workplaces

    International Nuclear Information System (INIS)

    Dorrian, M.-D.; Bailey, M.R.

    1995-01-01

    A survey of published values of Activity Median Aerodynamic Diameter (AMAD) measured in working environments was conducted to assist in the selection of a realistic default AMAD for occupational exposures. Results were compiled from 52 publications covering a wide variety of industries and workplaces. Reported values of AMAD from all studies ranged from 0.12 μm to 25 μm, and most were well fitted by a log-normal distribution with a median value of 4.4 μm. This supports the choice of a 5 μm default AMAD, as a realistic rounded value for occupational exposures, by the ICRP Task Group on Human Respiratory Tract Models for Radiological Protection and its acceptance by ICRP. Both the nuclear power and nuclear fuel handling industries gave median values of approximately 4 μm. Uranium mills gave a median value of 6.8 μm with AMADs frequently greater than 10 μm. High temperature and arc saw cutting operations generated submicron particles and occasionally, biomodal log-normal particle size distributions. It is concluded that in view of the wide range of AMADs found in the surveyed literature, greater emphasis should be placed on air sampling to characterise aerosol particle size distributions for individual work practices, especially as doses estimated with the new 5 μm default AMAD will not always be conservative. (author)

  5. Depositing nanometer-sized particles of metals onto carbon allotropes

    Science.gov (United States)

    Watson, Kent A. (Inventor); Fallbach, Michael J. (Inventor); Ghose, Sayata (Inventor); Smith, Joseph G. (Inventor); Delozier, Donavon M. (Inventor); Connell, John W. (Inventor)

    2010-01-01

    A process for depositing nanometer-sized metal particles onto a substrate in the absence of aqueous solvents, organic solvents, and reducing agents, and without any required pre-treatment of the substrate, includes preparing an admixture of a metal compound and a substrate by dry mixing a chosen amount of the metal compound with a chosen amount of the substrate; and supplying energy to the admixture in an amount sufficient to deposit zero valance metal particles onto the substrate. This process gives rise to a number of deposited metallic particle sizes which may be controlled. The compositions prepared by this process are used to produce polymer composites by combining them with readily available commodity and engineering plastics. The polymer composites are used as coatings, or they are used to fabricate articles, such as free-standing films, fibers, fabrics, foams, molded and laminated articles, tubes, adhesives, and fiber reinforced articles. These articles are well-suited for many applications requiring thermal conductivity, electrical conductivity, antibacterial activity, catalytic activity, and combinations thereof.

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

    International Nuclear Information System (INIS)

    Yuan, Y.C.; MacFarlane, D.

    1991-01-01

    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

  7. Initiator Systems Effect on Particle Coagulation and Particle Size Distribution in One-Step Emulsion Polymerization of Styrene

    Directory of Open Access Journals (Sweden)

    Baijun Liu

    2016-02-01

    Full Text Available Particle coagulation is a facile approach to produce large-scale polymer latex particles. This approach has been widely used in academic and industrial research owing to its higher polymerization rate and one-step polymerization process. Our work was motivated to control the extent (or time of particle coagulation. Depending on reaction parameters, particle coagulation is also able to produce narrowly dispersed latex particles. In this study, a series of experiments were performed to investigate the role of the initiator system in determining particle coagulation and particle size distribution. Under the optimal initiation conditions, such as cationic initiator systems or higher reaction temperature, the time of particle coagulation would be advanced to particle nucleation period, leading to the narrowly dispersed polymer latex particles. By using a combination of the Smoluchowski equation and the electrostatic stability theory, the relationship between the particle size distribution and particle coagulation was established: the earlier the particle coagulation, the narrower the particle size distribution, while the larger the extent of particle coagulation, the larger the average particle size. Combined with the results of previous studies, a systematic method controlling the particle size distribution in the presence of particle coagulation was developed.

  8. Particle-Size-Exclusion Clogging Regimes in Porous Media

    Science.gov (United States)

    Gerber, G.; Rodts, S.; Aimedieu, P.; Faure, P.; Coussot, P.

    2018-04-01

    From observations of the progressive deposition of noncolloidal particles by geometrical exclusion effects inside a 3D model porous medium, we get a complete dynamic view of particle deposits over a full range of regimes from transport over a long distance to clogging and caking. We show that clogging essentially occurs in the form of an accumulation of elements in pore size clusters, which ultimately constitute regions avoided by the flow. The clusters are dispersed in the medium, and their concentration (number per volume) decreases with the distance from the entrance; caking is associated with the final stage of this effect (for a critical cluster concentration at the entrance). A simple probabilistic model, taking into account the impact of clogging on particle transport, allows us to quantitatively predict all these trends up to a large cluster concentration, based on a single parameter: the clogging probability, which is a function of the confinement ratio. This opens the route towards a unification of the different fields of particle transport, clogging, caking, and filtration.

  9. Totally asymmetric exclusion processes with particles of arbitrary size

    International Nuclear Information System (INIS)

    Lakatos, Greg; Chou, Tom

    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 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

  10. 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.

  11. Analysis of filler particle levels and sizes in dental alginates

    Directory of Open Access Journals (Sweden)

    Hugo Lemes Carlo

    2010-06-01

    Full Text Available The aim of this study was to determine the inorganic filler fractions and sizes of commercially alginates. The inorganic particles volumetric fractions of five alginates - Jeltrate(J, Jeltrate Plus(JP, Jeltrate Chromatic Ortho(JC, Hydrogum(H and Ezact Krom(E were accessed by weighing a previously determined mass of each material in water before and after burning samples at 450 °C for 3 hours. Unsettled materials were soaked in acetone and chloroform and sputter-coated with gold for SEM evaluation of fillers' morphology and size. The results for the volumetric inorganic particle content were (%: J - 48.33, JP - 48.33, JC - 33.79, H - 37.55 and E - 40.55. The fillers presented a circular appearance with helical form and various perforations. Hydrogum fillers looked like cylindrical, perforated sticks. The mean values for fillers size were (μm: J - 12.91, JP - 13.67, JC - 13.44, E - 14.59 and H - 9 (diameter, 8.81 (length. The results of this study revealed differences in filler characteristics that could lead to different results when testing mechanical properties.

  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. Effect of Particle Size on Thermal Conductivity of Nanofluid

    Science.gov (United States)

    Chopkar, M.; Sudarshan, S.; Das, P. K.; Manna, I.

    2008-07-01

    Nanofluids, containing nanometric metallic or oxide particles, exhibit extraordinarily high thermal conductivity. It is reported that the identity (composition), amount (volume percent), size, and shape of nanoparticles largely determine the extent of this enhancement. In the present study, we have experimentally investigated the impact of Al2Cu and Ag2Al nanoparticle size and volume fraction on the effective thermal conductivity of water and ethylene glycol based nanofluid prepared by a two-stage process comprising mechanical alloying of appropriate Al-Cu and Al-Ag elemental powder blend followed by dispersing these nanoparticles (1 to 2 vol pct) in water and ethylene glycol with different particle sizes. The thermal conductivity ratio of nanofluid, measured using an indigenously developed thermal comparator device, shows a significant increase of up to 100 pct with only 1.5 vol pct nanoparticles of 30- to 40-nm average diameter. Furthermore, an analytical model shows that the interfacial layer significantly influences the effective thermal conductivity ratio of nanofluid for the comparable amount of nanoparticles.

  14. Shape, size, and distribution of magnetic particles in Bjurbole chondrules

    Science.gov (United States)

    Nava, David F.

    1994-01-01

    Chondrules from the Bjurbole chondritic meteorite (L4) exhibit saturation remanence magnetization (SIRM) values which vary over three orders of magnitude. REM values (Natural Remanence Magnetization/SIRM) for Allende (C3V) and Chainpur (LL3) are less than 0.01 but in Bjurbole some chondrules were found to have REM values greater than 0.1 with several greater than 0.2. REM values greater than 0.1 are abnormal and cannot be acquired during weak field cooling. If exposure to a strong field (whatever the source) during the chondrules' history is responsible for the high REM values, was such history associated with a different processing which might have resulted in different shape, size, and distribution of metal particles compared to chondrules having REM values of less than 0.01? Furthermore, magnetic hysteresis results show a broad range of magnetic hardness and other intrinsic magnetic properties. These features must be related to (1) size and amount of metal; and (2) properties of, and amount of, tetrataenite in the chondrules (all chondrules thus far subjected to thermomagnetic analysis show the presence of tetrataenite). A scanning electron microscopy (SEM) study is underway to determine the relationship between the shape, size, and distribution of metal particles within individual chondrules and the magnetic properties of these chondrules. Results from the SEM study in conjunction with magnetic property data may also help to discern effects from possible lightning strikes in the nebula prior to incorporation of the chondrules into the parent body.

  15. Interpretation of aerosol trace metal particle size distributions

    International Nuclear Information System (INIS)

    Johansson, T.B.; Van Grieken, R.E.; Winchester, J.W.

    1974-01-01

    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

  16. 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...

  17. 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

  18. Pore size determination from charged particle energy loss measurement

    International Nuclear Information System (INIS)

    Brady, F.P.; Armitage, B.H.

    1977-01-01

    A new method aimed at measuring porosity and mean pore size in materials has been developed at Harwell. The energy width or variance of a transmitted or backscattered charged particle beam is measured and related to the mean pore size via the assumption that the variance in total path length in the porous material is given by (Δx 2 )=na 2 , where n is the mean number of pores and a the mean pore size. It is shown on the basis of a general and rigorous theory of total path length distribution that this approximation can give rise to large errors in the mean pore size determination particularly in the case of large porosities (epsilon>0.5). In practice it is found that it is not easy to utilize fully the general theory because accurate measurements of the first four moments are required to determine the means and variances of the pore and inter-pore length distributions. Several models for these distributions are proposed. When these are incorporated in the general theory the determinations of mean pore size from experimental measurements on powder samples are in good agreement with values determined by other methods. (Auth.)

  19. Standing spin-wave mode structure and linewidth in partially disordered hexagonal arrays of perpendicularly magnetized sub-micron Permalloy discs

    International Nuclear Information System (INIS)

    Ross, N.; Kostylev, M.; Stamps, R. L.

    2014-01-01

    Standing spin wave mode frequencies and linewidths in partially disordered perpendicular magnetized arrays of sub-micron Permalloy discs are measured using broadband ferromagnetic resonance and compared to analytical results from a single, isolated disc. The measured mode structure qualitatively reproduces the structure expected from the theory. Fitted demagnetizing parameters decrease with increasing array disorder. The frequency difference between the first and second radial modes is found to be higher in the measured array systems than predicted by theory for an isolated disc. The relative frequencies between successive spin wave modes are unaffected by reduction of the long-range ordering of discs in the array. An increase in standing spin wave resonance linewidth at low applied magnetic fields is observed and grows more severe with increased array disorder.

  20. Observation of the dynamics of magnetically induced chains of sub-micron superparamagnetic beads in aqueous solutions by laser light scattering

    International Nuclear Information System (INIS)

    Tanizawa, Y; Tashiro, T; Sandhu, A; Ko, P J

    2013-01-01

    Optical monitoring the behaviour of magnetically induced self-assembled chains of superparamagnetic beads (SPBs) are of interest for biomedical applications such as biosensors. However, it is difficult to directly monitor magnetically induced self-assembly of sub-micron nano-beads with conventional optical microscopes. Here, we describe the optical observation of the dynamics of magnetically induced self-assembled rotating chains of 130 nm SPBs in aqueous solutions by laser light scattering. Magnetic fields of ∼1 kOe were applied to control the self-assembly chains of SPBs and their behaviour analyzed by monitoring the intensity of laser light scattered from the chain structures. We compared the light scattering from chains that were formed only by the application of external fields with chains formed by beads functionalized by EDC, where chemical reactions lead to the bonding of individual beads to form chains. The EDC experiments are a precursor to experiments on molecular recognition applications for biomedical diagnostics.

  1. Polymer-Particle Nanocomposites: Size and Dispersion Effects

    Science.gov (United States)

    Moll, Joseph

    Polymer-particle nanocomposites are used in industrial processes to enhance a broad range of material properties (e.g. mechanical, optical, electrical and gas permeability properties). This dissertation will focus on explanation and quantification of mechanical property improvements upon the addition of nanoparticles to polymeric materials. Nanoparticles, as enhancers of mechanical properties, are ubiquitous in synthetic and natural materials (e.g. automobile tires, packaging, bone), however, to date, there is no thorough understanding of the mechanism of their action. In this dissertation, silica (SiO2) nanoparticles, both bare and grafted with polystyrene (PS), are studied in polymeric matrices. Several variables of interest are considered, including particle dispersion state, particle size, length and density of grafted polymer chains, and volume fraction of SiO2. Polymer grafted nanoparticles behave akin to block copolymers, and this is critically leveraged to systematically vary nanoparticle dispersion and examine its role on the mechanical reinforcement in polymer based nanocomposites in the melt state. Rheology unequivocally shows that reinforcement is maximized by the formation of a transient, but long-lived, percolating polymer-particle network with the particles serving as the network junctions. The effects of dispersion and weight fraction of filler on nanocomposite mechanical properties are also studied in a bare particle system. Due to the interest in directional properties for many different materials, different means of inducing directional ordering of particle structures are also studied. Using a combination of electron microscopy and x-ray scattering, it is shown that shearing anisotropic NP assemblies (sheets or strings) causes them to orient, one in front of the other, into macroscopic two-dimensional structures along the flow direction. In contrast, no such flow-induced ordering occurs for well dispersed NPs or spherical NP aggregates! This work

  2. Statistical properties of the normalized ice particle size distribution

    Science.gov (United States)

    Delanoë, Julien; Protat, Alain; Testud, Jacques; Bouniol, Dominique; Heymsfield, A. J.; Bansemer, A.; Brown, P. R. A.; Forbes, R. M.

    2005-05-01

    Testud et al. (2001) have recently developed a formalism, known as the "normalized particle size distribution (PSD)", which consists in scaling the diameter and concentration axes in such a way that the normalized PSDs are independent of water content and mean volume-weighted diameter. In this paper we investigate the statistical properties of the normalized PSD for the particular case of ice clouds, which are known to play a crucial role in the Earth's radiation balance. To do so, an extensive database of airborne in situ microphysical measurements has been constructed. A remarkable stability in shape of the normalized PSD is obtained. The impact of using a single analytical shape to represent all PSDs in the database is estimated through an error analysis on the instrumental (radar reflectivity and attenuation) and cloud (ice water content, effective radius, terminal fall velocity of ice crystals, visible extinction) properties. This resulted in a roughly unbiased estimate of the instrumental and cloud parameters, with small standard deviations ranging from 5 to 12%. This error is found to be roughly independent of the temperature range. This stability in shape and its single analytical approximation implies that two parameters are now sufficient to describe any normalized PSD in ice clouds: the intercept parameter N*0 and the mean volume-weighted diameter Dm. Statistical relationships (parameterizations) between N*0 and Dm have then been evaluated in order to reduce again the number of unknowns. It has been shown that a parameterization of N*0 and Dm by temperature could not be envisaged to retrieve the cloud parameters. Nevertheless, Dm-T and mean maximum dimension diameter -T parameterizations have been derived and compared to the parameterization of Kristjánsson et al. (2000) currently used to characterize particle size in climate models. The new parameterization generally produces larger particle sizes at any temperature than the Kristjánsson et al. (2000

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

    International Nuclear Information System (INIS)

    George, A.C.; Hinchliffe, L.; Sladowski, R.

    1975-01-01

    The size distribution of radon daughters was measured in several uranium mines using four compact diffusion batteries and a round jet cascade impactor. Simultaneously, measurements were made of uncombined fractions of radon daughters, radon concentration, working level, and particle concentration. The size distributions found for radon daughters were log normal. The activity median diameters ranged from 0.09 μm to 0.3 μm with a mean value of 0.17 μm. Geometric standard deviations were in the range from 1.3 to 4 with a mean value of 2.7. Uncombined fractions expressed in accordance with the ICRP definition ranged from 0.004 to 0.16 with a mean value of 0.04. The radon daughter sizes in these mines are greater than the sizes assumed by various authors in calculating respiratory tract dose. The disparity may reflect the widening use of diesel-powered equipment in large uranium mines. (U.S.)

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

    International Nuclear Information System (INIS)

    George, A.C.; Hinchliffe, L.; Sladowski, R.

    1977-07-01

    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

  5. Atherogenic lipoprotein particle size and concentrations and the effect of pravastatin in children with familial hypercholesterolemia

    NARCIS (Netherlands)

    van der Graaf, Anouk; Rodenburg, Jessica; Vissers, Maud N.; Hutten, Barbara A.; Wiegman, Albert; Trip, Mieke D.; Stroes, Erik S. G.; Wijburg, Frits A.; Otvos, James D.; Kastelein, John J. P.

    2008-01-01

    OBJECTIVE: To determine lipoprotein particle concentrations and size in children with familial hypercholesterolemia (FH) and investigate the effect of pravastatin therapy on these measures. STUDY DESIGN: Lipoprotein particle concentrations and sizes were examined by nuclear magnetic resonance (NMR)

  6. Progress towards sub-micron hard x-ray imaging using elliptically bent mirrors and its applications

    International Nuclear Information System (INIS)

    MacDowell, A.A.; Lamble, G.M.; Celestre, R.S.; Padmore, H.A.; Chang, C.H.; Patel, J.R.

    1998-06-01

    The authors have developed an x-ray micro-probe facility utilizing mirror bending techniques that allow white light x-rays (4--12keV) from the Advanced light Source Synchrotron to be focused down to spot sizes of micron spatial dimensions. They have installed a 4 crystal monochromator prior to the micro-focusing mirrors. The monochromator is designed such that it can move out of the way of the input beam, and allows the same micron sized sample to be illuminated with either white or monochromatic radiation. Illumination of the sample with white light allows for elemental mapping and Laue x-ray diffraction, while illumination of the sample with monochromatic light allows for elemental mapping (with reduced background), micro-X-ray absorption spectroscopy and micro-diffraction. The performance of the system will be described as will some of the initial experiments that cover the various disciplines of Earth, Material and Life Sciences

  7. Progress towards sub-micron hard x-ray imaging using elliptically bent mirrors and its applications

    Energy Technology Data Exchange (ETDEWEB)

    MacDowell, A.A.; Lamble, G.M.; Celestre, R.S.; Padmore, H.A. [Lawrence Berkeley National Lab., CA (United States); Chang, C.H.; Patel, J.R. [Lawrence Berkeley National Lab., CA (United States). Advanced Light Source Div.]|[Stanford Univ., CA (United States)

    1998-06-01

    The authors have developed an x-ray micro-probe facility utilizing mirror bending techniques that allow white light x-rays (4--12keV) from the Advanced light Source Synchrotron to be focused down to spot sizes of micron spatial dimensions. They have installed a 4 crystal monochromator prior to the micro-focusing mirrors. The monochromator is designed such that it can move out of the way of the input beam, and allows the same micron sized sample to be illuminated with either white or monochromatic radiation. Illumination of the sample with white light allows for elemental mapping and Laue x-ray diffraction, while illumination of the sample with monochromatic light allows for elemental mapping (with reduced background), micro-X-ray absorption spectroscopy and micro-diffraction. The performance of the system will be described as will some of the initial experiments that cover the various disciplines of Earth, Material and Life Sciences.

  8. Contact freezing of supercooled cloud droplets on collision with mineral dust particles: effect of particle size

    Science.gov (United States)

    Hoffmann, Nadine; Duft, Denis; Kiselev, Alexei; Leisner, Thomas

    2013-04-01

    The contact freezing of supercooled cloud droplets is one of the potentially important and the least investigated heterogeneous mechanism of ice formation in the tropospheric clouds [1]. On the time scales of cloud lifetime the freezing of supercooled water droplets via contact mechanism may occur at higher temperature compared to the same IN immersed in the droplet. However, the laboratory experiments of contact freezing are very challenging due to the number of factors affecting the probability of ice formation. In our experiment we study single water droplets freely levitated in the laminar flow of mineral dust particles acting as the contact freezing nuclei. By repeating the freezing experiment sufficient number of times we are able to reproduce statistical freezing behavior of large ensembles of supercooled droplets and measure the average rate of freezing events. We show that the rate of freezing at given temperature is governed only by the rate of droplet -particle collision and by the properties of the contact ice nuclei. In this contribution we investigate the relationship between the freezing probability and the size of mineral dust particle (represented by illite) and show that their IN efficiency scales with the particle size. Based on this observation, we discuss the similarity between the freezing of supercooled water droplets in immersion and contact modes and possible mechanisms of apparent enhancement of the contact freezing efficiency. [1] - K.C. Young, The role of contact nucleation in ice phase initiation in clouds, Journal of the Atmospheric Sciences 31, 1974

  9. Measuring depths of sub-micron tracks in a CR-39 detector from replicas using Atomic Force Microscopy

    International Nuclear Information System (INIS)

    Yu, K.N.; Ng, F.M.F.; Nikezic, D.

    2005-01-01

    One of the challenging tasks in the application of solid-state nuclear track detectors (SSNTDs) is the measurement of the depth of the tracks, in particular, the shallow ones resulting from short etching periods. In the present work, a method is proposed to prepare replicas of tracks from α particles in the CR-39 SSNTDs and to measure their heights using atomic force microscopy (AFM). After irradiation, the detectors were etched in a 6.25N aqueous solution of NaOH maintained at 70 deg. C. The etched detectors were immersed into a beaker of the replicating fluid, which was placed in a water bath under ultrasonic vibration and maintained at room temperature to facilitate the filling of the etched tracks with the replicating fluid. As an example of application, these results have been used to derive a V function for the CR-39 detectors used in the present study (for the specified etching conditions)

  10. 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.

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

    International Nuclear Information System (INIS)

    Morales-Maldonado, Emilio Raymundo; Casanova-Lugo, Fernando

    2015-01-01

    The mixtures of organic and inorganic materials used in the preparation of a new material, particle size, proportion and their response in plant were reviewed. Agricultural wastes are considered a pollutant reservoir in Mexico; however, for another perspective this represent an industry with great potential. The nutrients ingested by animals represent nutriments available for plants when properly recycled. The production of compost and vermicompost is an option that minimize the risk of contamination and improve quality. Both processes are an alternative for organic production. The efficiency of irrigation and fertilization are affected for the reducing the volumen of an organic material incresase compaction and compression of roots. The mixtures with inorganic materials are used in the development of a new material to obtain better growing conditions for the plant. (author) [es

  12. Effect of particle size on the thermoluminescent response of hydroxyapatite

    International Nuclear Information System (INIS)

    Barrera V, A.; Zarate M, J.; Contreras, M. E.; Rivera M, T.

    2016-10-01

    We present the study of the structural characterization and the thermoluminescent response of the hydroxyapatite as a function of the calcination temperature and the effect of the particle size. For precipitation synthesis, calcium nitrate (Ca(NO_3)_2 and dibasic ammonium phosphate ((NH_4)_2HPO_4) were used as precursors and ammonium hydroxide (NH_4OH) as a ph controlling agent. The characterization of the samples was carried out by the techniques of X-ray diffraction, scanning electron microscopy and infrared spectroscopy. The powders obtained are composed of hydroxyapatite, with a different degree of dehydroxylation. The thermoluminescent characterization indicates that at higher calcination temperature there is a higher thermoluminescent response, the calcined powders at 1300 degrees Celsius show a very well defined brightness curve with a higher intensity, with its maximum intensity located at a temperature of 210 degrees Celsius, which indicates that this material can be used as a dosimeter. (Author)

  13. Optimation of particle size and composition in fabrication of granite particle composite floortiles

    International Nuclear Information System (INIS)

    Budiarto; Parikin; Mohammad-Dani

    2004-01-01

    Granite particle composite floortile materials, that have epoxy matrix, may be utilized as water resist and ductile materials. The utility of composite materials for industrial households is, however, very important and very promising indeed. Starting from powdering the granite refuges into particles of 100, 140 and 200 in mesh, the powder was mixed by epoxy containing versamid hardener and stirred till highly homogenized. Specimens were mould in glass frame and dried in ambient temperature for 48 hours. The specimens were prepared into certain dimensions, conformed to testing needs: hardness, density, compression and bending. The hardness and density data show clearly the value change of particulate composition (34, 40, 50 and 70) and matrix (66, 60, 50 and 30) as well. From bending and compression tests, the optimum grain size (μm) and composition (%) of granite particles reveal between the number of 120-123 and 55-61 respectively. The accurate point of the values can be determined by using differential method. As conclusion, for the better mechanical properties of granite particles composite floortiles, the grains should be 121 in μm and 57% composition of granite particles

  14. Intrinsic speckle noise in in-line particle holography due to polydisperse and continuous particle sizes

    Science.gov (United States)

    Edwards, Philip J.; Hobson, Peter R.; Rodgers, G. J.

    2000-08-01

    In-line particle holography is subject to image deterioration due to intrinsic speckle noise. The resulting reduction in the signal to noise ratio (SNR) of the replayed image can become critical for applications such as holographic particle velocimetry (HPV) and 3D visualisation of marine plankton. Work has been done to extend the mono-disperse model relevant to HPV to include poly-disperse particle fields appropriate for the visualisation of marine plankton. Continuous and discrete particle fields are both considered. It is found that random walk statistics still apply for the poly-disperse case. The speckle field is simply the summation of the individual speckle patters due to each scatter size. Therefor the characteristic speckle parameter (which encompasses particle diameter, concentration and sample depth) is alos just the summation of the individual speckle parameters. This reduces the SNR calculation to the same form as for the mono-disperse case. For the continuous situation three distributions, power, exponential and Gaussian are discussed with the resulting SNR calcuated. The work presented here was performed as part of the Holomar project to produce a working underwater holographic camera for recording plankton.

  15. High performance imaging of relativistic soft X-ray harmonics by sub-micron resolution LiF film detectors

    Energy Technology Data Exchange (ETDEWEB)

    Pikuz, Tatiana; Faenov, Anatoly [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kizugawa, Kyoto 619-0215 (Japan); Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Pirozhkov, Alexander; Esirkepov, Timur; Koga, James; Nakamura, Tatsufumi; Bulanov, Sergei; Fukuda, Yuji; Hayashi, Yukio; Kotaki, Hideyuki; Kando, Masaki [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kizugawa, Kyoto 619-0215 (Japan); Astapov, Artem; Pikuz, Sergey Jr. [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Klushin, Georgy [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); International Laser Center of M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Nagorskiy, Nikolai; Magnitskiy, Sergei [International Laser Center of M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Kato, Yoshiaki [The Graduate School for the Creation of New Photonics Industries, Hamamatsu, Shizuoka (Japan)

    2012-12-15

    The spectrum variation and the coherent properties of the high-order harmonics (HOH) generated by an oscillating electron spikes formed at the joint of the boundaries of a cavity and a bow wave, which are created by a relativistically self-focusing laser in underdense gas jet plasma, are investigated. This new mechanism for HOH generation efficiently produces emission from ultraviolet up to the XUV ''water window'' spectral range. To characterize such source in the wide spectral range a diffraction imaging technique is applied. High spatial resolution EUV and soft X-ray LiF film detector have been used for precise measurements of diffraction patterns. The measurements under observation angle of 8 to the axis of laser beam propagation have been performed. The diffraction patterns were observed on the detector clearly, when the square mesh was placed at the distance of 500 mm from the output of plasma and at the distance of 27.2 mm in front of the detector. It is shown that observed experimental patterns are well consistent with modeled ones for theoretical HOH spectrum, provided by particle-in-cell simulations of a relativistic-irradiance laser pulse interaction with underdense plasma (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    International Nuclear Information System (INIS)

    Muhammad-Priyatna; Otto-Pribadi-Ruslanto

    2001-01-01

    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)

  17. Discrete element method modeling of the triboelectric charging of polyethylene particles: Can particle size distribution and segregation reduce the charging?

    International Nuclear Information System (INIS)

    Konopka, Ladislav; Kosek, Juraj

    2015-01-01

    Polyethylene particles of various sizes are present in industrial gas-dispersion reactors and downstream processing units. The contact of the particles with a device wall as well as the mutual particle collisions cause electrons on the particle surface to redistribute in the system. The undesirable triboelectric charging results in several operational problems and safety risks in industrial systems, for example in the fluidized-bed polymerization reactor. We studied the charging of polyethylene particles caused by the particle-particle interactions in gas. Our model employs the Discrete Element Method (DEM) describing the particle dynamics and incorporates the ‘Trapped Electron Approach’ as the physical basis for the considered charging mechanism. The model predicts the particle charge distribution for systems with various particle size distributions and various level of segregation. Simulation results are in a qualitative agreement with experimental observations of similar particulate systems specifically in two aspects: 1) Big particles tend to gain positive charge and small particles the negative one. 2) The wider the particle size distribution is, the more pronounced is the charging process. Our results suggest that not only the size distribution, but also the effect of the spatial segregation of the polyethylene particles significantly influence the resulting charge distribution ‘generated’ in the system. The level of particle segregation as well as the particle size distribution of polyethylene particles can be in practice adjusted by the choice of supported catalysts, by the conditions in the fluidized-bed polymerization reactor and by the fluid dynamics. We also attempt to predict how the reactor temperature affects the triboelectric charging of particles. (paper)

  18. Effect of Finite Particle Size on Convergence of Point Particle Models in Euler-Lagrange Multiphase Dispersed Flow

    Science.gov (United States)

    Nili, Samaun; Park, Chanyoung; Haftka, Raphael T.; Kim, Nam H.; Balachandar, S.

    2017-11-01

    Point particle methods are extensively used in simulating Euler-Lagrange multiphase dispersed flow. When particles are much smaller than the Eulerian grid the point particle model is on firm theoretical ground. However, this standard approach of evaluating the gas-particle coupling at the particle center fails to converge as the Eulerian grid is reduced below particle size. We present an approach to model the interaction between particles and fluid for finite size particles that permits convergence. We use the generalized Faxen form to compute the force on a particle and compare the results against traditional point particle method. We apportion the different force components on the particle to fluid cells based on the fraction of particle volume or surface in the cell. The application is to a one-dimensional model of shock propagation through a particle-laden field at moderate volume fraction, where the convergence is achieved for a well-formulated force model and back coupling for finite size particles. Comparison with 3D direct fully resolved numerical simulations will be used to check if the approach also improves accuracy compared to the point particle model. Work supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

  19. Thermal and particle size distribution effects on the ferromagnetic resonance in magnetic fluids

    International Nuclear Information System (INIS)

    Marin, C.N.

    2006-01-01

    Thermal and particle size distribution effects on the ferromagnetic resonance of magnetic fluids were theoretically investigated, assuming negligible interparticle interactions and neglecting the viscosity of the carrier liquid. The model is based on the usual approach for the ferromagnetic resonance description of single-domain magnetic particle systems, which was amended in order to take into account the finite particle size effect, the particle size distribution and the orientation mobility of the particles within the magnetic fluid. Under these circumstances the shape of the resonance line, the resonance field and the line width are found to be strongly affected by the temperature and by the particle size distribution of magnetic fluids

  20. Particle size effects on protein and virus-like particle adsorption on perfusion chromatography media.

    Science.gov (United States)

    Wu, Yige; Abraham, Dicky; Carta, Giorgio

    2015-01-02

    The resin structure, chromatographic behavior, and adsorption kinetics of proteins and virus-like-particles (VLPs) are studied for POROS HS 20 and POROS HS 50 (23 and 52 μm mean diameter, respectively) to determine the effects of particle size on perfusion chromatography and to determine the predictive ability of available models. Transmission electron microscopy (TEM) and inverse size-exclusion chromatography (iSEC) show similar structures for the two resins, both containing 200-1000 nm pores that transect a network of much smaller pores. For non-binding conditions, trends of the height equivalent to a theoretical plate (HETP) as a function of reduced velocity are consistent with perfusion. The estimated intraparticle flow fractions for these conditions are 0.0018 and 0.00063 for POROS HS 20 and HS 50, respectively. For strong binding conditions, confocal laser scanning microscopy (CLSM) shows asymmetrical intraparticle concentrations profiles and enhanced rates of IgG adsorption on POROS HS 20 at 1000 cm/h. The corresponding effective diffusivity under flow is 2-3 times larger than for non-flow conditions and much larger than observed for POROS HS 50, consistent with available models. For VLPs, however, adsorption is confined to a thin layer near the particle surface for both resins, suggesting that the bound VLPs block the pores. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Particle contamination effects in EUVL: enhanced theory for the analytical determination of critical particle sizes

    Science.gov (United States)

    Brandstetter, Gerd; Govindjee, Sanjay

    2012-03-01

    Existing analytical and numerical methodologies are discussed and then extended in order to calculate critical contamination-particle sizes, which will result in deleterious effects during EUVL E-chucking in the face of an error budget on the image-placement-error (IPE). The enhanced analytical models include a gap dependant clamping pressure formulation, the consideration of a general material law for realistic particle crushing and the influence of frictional contact. We present a discussion of the defects of the classical de-coupled modeling approach where particle crushing and mask/chuck indentation are separated from the global computation of mask bending. To repair this defect we present a new analytic approach based on an exact Hankel transform method which allows a fully coupled solution. This will capture the contribution of the mask indentation to the image-placement-error (estimated IPE increase of 20%). A fully coupled finite element model is used to validate the analytical models and to further investigate the impact of a mask back-side CrN-layer. The models are applied to existing experimental data with good agreement. For a standard material combination, a given IPE tolerance of 1 nm and a 15 kPa closing pressure, we derive bounds for single particles of cylindrical shape (radius × height < 44 μm) and spherical shape (diameter < 12 μm).

  2. Fabrication of sub-micron surface structures on copper, stainless steel and titanium using picosecond laser interference patterning

    Energy Technology Data Exchange (ETDEWEB)

    Bieda, Matthias, E-mail: matthias.bieda@iws.fraunhofer.de [Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, 01277 Dresden (Germany); Siebold, Mathias, E-mail: m.siebold@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstr. 400, 01328 Dresden (Germany); Lasagni, Andrés Fabián, E-mail: andres_fabian.lasagni@tu-dresden.de [Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, 01277 Dresden (Germany); Technische Universität Dresden, Institut für Fertigungstechnik, 01062 Dresden (Germany)

    2016-11-30

    Highlights: • Laser interference patterning is introduced to generate sub-micrometer surface pattern. • The two-temperature model is applied to ps-laser interference patterning of metals. • Line-like structures with a pitch of 0.7 μm were fabricated on SAE 304, Ti and Cu. • The process is governed by a photo-thermal mechanism for a pulse duration of 35 ps. • A “cold”-ablation process for metals requires a pulse duration shorter than 10 ps. - Abstract: Picosecond direct laser interference patterning (ps-DLIP) is investigated theoretically and experimentally for the bulk metals copper, stainless steel and titanium. While surface texturing with nanosecond pulses is limited to feature sizes in the micrometer range, utilizing picosecond pulses can lead to sub-micrometer structures. The modelling and simulation of ps-DLIP are based on the two-temperature model and were carried out for a pulse duration of 35 ps at 515 nm wavelength and a laser fluence of 0.1 J/cm{sup 2}. The subsurface temperature distribution of both electrons and phonons was computed for periodic line-like structures with a pitch of 0.8 μm. The increase in temperature rises for a lower absorption coefficient and a higher thermal conductivity. The distance, at which the maximum subsurface temperature occurs, increases for a small absorption coefficient. High absorption and low thermal conductivity minimize internal heating and give rise to a pronounced surface micro topography with pitches smaller than 1 μm. In order to confirm the computed results, periodic line-like surface structures were produced using two interfering beams of a Yb:YAG-Laser with 515 nm wavelength and a pulse duration of 35 ps. It was possible to obtain a pitch of 0.7 μm on the metallic surfaces.

  3. Estimating particle number size distributions from multi-instrument observations with Kalman Filtering

    Energy Technology Data Exchange (ETDEWEB)

    Viskari, T.

    2012-07-01

    Atmospheric aerosol particles have several important effects on the environment and human society. The exact impact of aerosol particles is largely determined by their particle size distributions. However, no single instrument is able to measure the whole range of the particle size distribution. Estimating a particle size distribution from multiple simultaneous measurements remains a challenge in aerosol physical research. Current methods to combine different measurements require assumptions concerning the overlapping measurement ranges and have difficulties in accounting for measurement uncertainties. In this thesis, Extended Kalman Filter (EKF) is presented as a promising method to estimate particle number size distributions from multiple simultaneous measurements. The particle number size distribution estimated by EKF includes information from prior particle number size distributions as propagated by a dynamical model and is based on the reliabilities of the applied information sources. Known physical processes and dynamically evolving error covariances constrain the estimate both over time and particle size. The method was tested with measurements from Differential Mobility Particle Sizer (DMPS), Aerodynamic Particle Sizer (APS) and nephelometer. The particle number concentration was chosen as the state of interest. The initial EKF implementation presented here includes simplifications, yet the results are positive and the estimate successfully incorporated information from the chosen instruments. For particle sizes smaller than 4 micrometers, the estimate fits the available measurements and smooths the particle number size distribution over both time and particle diameter. The estimate has difficulties with particles larger than 4 micrometers due to issues with both measurements and the dynamical model in that particle size range. The EKF implementation appears to reduce the impact of measurement noise on the estimate, but has a delayed reaction to sudden

  4. Synthesis and self-assembly of dumbbell shaped ZnO sub-micron structures using low temperature chemical bath deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Borade, P. [National Centre for Nanoscience and Nanotechnology, University of Mumbai, Kalina Campus, Santacruz (E), Mumbai 400098 (India); Joshi, K.U. [Anton-Paar India Pvt. Ltd., Thane (W), 400607 (India); Gokarna, A.; Lerondel, G. [Laboratoire de Nanotechnologie et D' Instrumentation Optique, Institut Charles Delaunay, CNRS UMR 6281, Université de Technologie de Troyes, 12 Rue Marie Curie, BP 2060, 10010 Troyes (France); Walke, P. [National Centre for Nanoscience and Nanotechnology, University of Mumbai, Kalina Campus, Santacruz (E), Mumbai 400098 (India); Late, D. [National Chemical Laboratory (NCL), Pune 400027 (India); Jejurikar, S.M., E-mail: jejusuhas@gmail.com [National Centre for Nanoscience and Nanotechnology, University of Mumbai, Kalina Campus, Santacruz (E), Mumbai 400098 (India)

    2016-02-01

    We report well dispersed horizontal growth of ZnO sub-micron structures using simplest technique ever known i.e. chemical bath deposition (CBD). A set of samples were prepared under two different cases A) dumbbell shaped ZnO grown in CBD bath and B) tubular ZnO structures evolved from dumbbell shaped structures by dissolution mechanism. Single phase wurtzite ZnO formation is confirmed using X-ray diffraction (XRD) technique in both cases. From the morphological investigations performed using scanning electron microscopy (SEM), sample prepared under case A indicate formation of hex bit tool (HBT) shaped ZnO crystals, which observed to self-organize to form dumbbell structures. Further these microstructures are then converted into tubular structures as a fragment of post CBD process. The possible mechanism responsible for the self-assembly of HBT units to form dumbbell structures is discussed. Observed free excitonic peak located at 370 nm in photoluminescence (PL) spectra recorded at 18 K indicate that the micro/nanostructures synthesized using CBD are of high optical quality. - Highlights: • Controlled growth of Dumbbell shaped ZnO using Chemical Bath Deposition (CBD). • Growth mechanism of dumbbell shaped ZnO by self-assembling was discussed. • Quick Transformation of ZnO dumbbell structures in to tubular structures by dissolution. • Sharp UV Emission at 370 nm from both dumbbell and tubular structures.

  5. Estimation of the sizes of hot nuclear systems from particle-particle large angle kinematical correlations

    International Nuclear Information System (INIS)

    La Ville, J.L.; Bizard, G.; Durand, D.; Jin, G.M.; Rosato, E.

    1990-06-01

    Light fragment emission, when triggered by large transverse momentum protons shows specific kinematical correlations due to recoil effects of the excited emitting source. Such effects have been observed in azimuthal angular distributions of He-particles produced in collisions induced by 94 MeV/u 16 0 ions on Al, Ni and Au targets. A model calculation assuming a two-stage mechanism (formation and sequential decay of a hot source) gives a good description of these whole data. From this succesfull confrontation, it is possible to estimate the size of the emitting system

  6. Tailoring particle size and morphology of colloidal Ag particles via chemical precipitation for Ag-BSCCO composites

    International Nuclear Information System (INIS)

    Medendorp, N.W. Jr.; Bowman, K.J.; Trumble, K.P.

    1996-01-01

    The chemical precipitation of silver particles is an effective method for tailoring the particle size and morphology. This article investigates a chemical precipitation method for producing silver colloids, and how processing parameters affected particle size, morphology and adherence. Decreasing the silver nitrate concentration during precipitation with sodium borohydride decreased the colloidal silver particle size. Decreasing the addition rate of the reducing agent produced faceted particles. Reversing the reactant addition order also changed the particle size and the morphology. Precipitated colloids demonstrated a difference between the growth-dominated and the equilibrium structures. Co-dispersing Bi-based superconducting platelets during precipitation allowed Ag colloids to preferentially nucleate on the platelets and to remain adhered even after the additional processing. (orig.)

  7. Particle size analyses in and around mineral sands operations

    International Nuclear Information System (INIS)

    Koperski, J.

    1993-01-01

    Activity Median Aerodynamic Diameters (AMADs) of airborne dust in and around West Australian heavy mineral sands operations have been investigated. Monitoring of dry separation plant workers, positional monitoring of the plant environment and positional monitoring outdoors were conducted. The number of AMAD detections was 49, 21 and 37, respectively. Mean AMAD values of 15.7μm (GSD 2.9) for personal monitoring, 4.6μm (GSD 3.5) for positional monitoring indoors and 2.7 μm (GSD 4.8) for hi-vol positional monitoring outdoors were obtained. The size distribution of airborne radioactivity was observed to be log-normal. Applying the ICRP 30 inhalation model (ICRP 1979) and both, ICRP 26 (ICRP 1977) and ICRP 60 (ICRP 1990) recommendations, intake-to-dose conversion factors for internal alpha exposure from the Th series radionuclides (in secular equilibrium, solubility Class Y) associated with airborne dust were subsequently assessed. It has been concluded that no single AMAD value would characterise heavy mineral sands operations. In the areas of the greatest radiological impact (dry separation plants indoors) emphasis should be focused upon personal monitoring strategies. In the areas of a lower impact (outdoors), a positional cascade impactor data may be used for personal AMAD assessment. Application of the reference 1μm AMAD value may lead to an over 5-fold overestimation of internal doses for the dry separation plant workers and to about 2-fold dose overestimation for the other workers. Hence, the need and importance of conducting site-specific particle size analyses for individual mineral sands operations. 13 refs., 4 tabs., 6 figs

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

    International Nuclear Information System (INIS)

    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. (paper)

  9. 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......-resolved observations. We present size-resolved particle number fluxes for sub-100-nm particle diameters (Dp) over a deciduous forest derived using eddy covariance applied to data from a fast mobility particle sizer. The size-resolved particle number fluxes in 18 diameters between 8 and 100 nm were collected during...... leaf-on and are statistically robust. Particle deposition velocities normalized by friction velocity (v d +) are approximately four times smaller than comparable values for coniferous forests reported elsewhere. Comparison of the data with output from a new one-dimensional mechanistic particle...

  10. Transmission and fractionation of micro-sized particle suspensions

    NARCIS (Netherlands)

    Brans, G.B.P.W.; Dinther, van A.M.C.; Odum, B.; Schroën, C.G.P.H.; Boom, R.M.

    2007-01-01

    In processes aimed at the fractionation of a multi-component feed stream, transmission of particles through the membrane is at least as important as retention of larger particles. In this paper, we describe the mechanisms of transmission of mono-disperse latex particles through a polymer membrane.

  11. Sensitivity of Particle Size in Discrete Element Method to Particle Gas Method (DEM_PGM) Coupling in Underbody Blast Simulations

    Science.gov (United States)

    2016-06-12

    Particle Size in Discrete Element Method to Particle Gas Method (DEM_PGM) Coupling in Underbody Blast Simulations Venkatesh Babu, Kumar Kulkarni, Sanjay...buried in soil viz., (1) coupled discrete element & particle gas methods (DEM-PGM) and (2) Arbitrary Lagrangian-Eulerian (ALE), are investigated. The...DEM_PGM and identify the limitations/strengths compared to the ALE method. Discrete Element Method (DEM) can model individual particle directly, and

  12. Preparation of gold nanoparticles and determination of their particles size via different methods

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad; Usanase, Gisele [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France); Oulmi, Kafia; Aberkane, Fairouz; Bendaikha, Tahar [Laboratory of Chemistry and Environmental Chemistry(LCCE), Faculty of Science, Material Science Department, University of Batna, 05000 (Algeria); Fessi, Hatem [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France); Zine, Nadia [Institut des Sciences Analytiques (ISA), Université Lyon, Université Claude Bernard Lyon-1, UMR-5180, 5 rue de la Doua, F-69100 Villeurbanne (France); Agusti, Géraldine [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France); Errachid, El-Salhi [Institut des Sciences Analytiques (ISA), Université Lyon, Université Claude Bernard Lyon-1, UMR-5180, 5 rue de la Doua, F-69100 Villeurbanne (France); Elaissari, Abdelhamid, E-mail: elaissari@lagep.univ-lyon1.fr [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France)

    2016-07-15

    Graphical abstract: Preparation of gold nanoparticles via NaBH{sub 4} reduction method, and determination of their particle size, size distribution and morphology by using different techniques. - Highlights: • Gold nanoparticles were synthesized by NaBH{sub 4} reduction method. • Excess of reducing agent leads to tendency of aggregation. • The particle size, size distribution and morphology were investigated. • Particle size was determined both experimentally as well as theoretically. - Abstract: Gold nanoparticles have been used in various applications covering both electronics, biosensors, in vivo biomedical imaging and in vitro biomedical diagnosis. As a general requirement, gold nanoparticles should be prepared in large scale, easy to be functionalized by chemical compound of by specific ligands or biomolecules. In this study, gold nanoparticles were prepared by using different concentrations of reducing agent (NaBH{sub 4}) in various formulations and their effect on the particle size, size distribution and morphology was investigated. Moreover, special attention has been dedicated to comparison of particles size measured by various techniques, such as, light scattering, transmission electron microscopy, UV spectrum using standard curve and particles size calculated by using Mie theory and UV spectrum of gold nanoparticles dispersion. Particle size determined by various techniques can be correlated for monodispersed particles and excess of reducing agent leads to increase in the particle size.

  13. Preparation of gold nanoparticles and determination of their particles size via different methods

    International Nuclear Information System (INIS)

    Iqbal, Muhammad; Usanase, Gisele; Oulmi, Kafia; Aberkane, Fairouz; Bendaikha, Tahar; Fessi, Hatem; Zine, Nadia; Agusti, Géraldine; Errachid, El-Salhi; Elaissari, Abdelhamid

    2016-01-01

    Graphical abstract: Preparation of gold nanoparticles via NaBH_4 reduction method, and determination of their particle size, size distribution and morphology by using different techniques. - Highlights: • Gold nanoparticles were synthesized by NaBH_4 reduction method. • Excess of reducing agent leads to tendency of aggregation. • The particle size, size distribution and morphology were investigated. • Particle size was determined both experimentally as well as theoretically. - Abstract: Gold nanoparticles have been used in various applications covering both electronics, biosensors, in vivo biomedical imaging and in vitro biomedical diagnosis. As a general requirement, gold nanoparticles should be prepared in large scale, easy to be functionalized by chemical compound of by specific ligands or biomolecules. In this study, gold nanoparticles were prepared by using different concentrations of reducing agent (NaBH_4) in various formulations and their effect on the particle size, size distribution and morphology was investigated. Moreover, special attention has been dedicated to comparison of particles size measured by various techniques, such as, light scattering, transmission electron microscopy, UV spectrum using standard curve and particles size calculated by using Mie theory and UV spectrum of gold nanoparticles dispersion. Particle size determined by various techniques can be correlated for monodispersed particles and excess of reducing agent leads to increase in the particle size.

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

    International Nuclear Information System (INIS)

    Tang Hong; Lin Jianzhong

    2011-01-01

    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.

  15. Size measurement of radioactive aerosol particles in intense radiation fields using wire screens and imaging plates

    Energy Technology Data Exchange (ETDEWEB)

    Oki, Yuichi; Tanaka, Toru; Takamiya, Koichi; Ishi, Yoshihiro; UesugI, Tomonori; Kuriyama, Yasutoshi; Sakamoto, Masaaki; Ohtsuki, Tsutomu [Kyoto University Research Reactor Institute, Osaka (Japan); Nitta, Shinnosuke [Graduate School of Engineering, Kyoto University, Kyoto (Japan); Osada, Naoyuki [Advanced Science Research Center, Okayama University, Okayama (Japan)

    2016-09-15

    Very fine radiation-induced aerosol particles are produced in intense radiation fields, such as high-intensity accelerator rooms and containment vessels such as those in the Fukushima Daiichi nuclear power plant (FDNPP). Size measurement of the aerosol particles is very important for understanding the behavior of radioactive aerosols released in the FDNPP accident and radiation safety in high-energy accelerators. A combined technique using wire screens and imaging plates was developed for size measurement of fine radioactive aerosol particles smaller than 100 nm in diameter. This technique was applied to the radiation field of a proton accelerator room, in which radioactive atoms produced in air during machine operation are incorporated into radiation-induced aerosol particles. The size of 11C-bearing aerosol particles was analyzed using the wire screen technique in distinction from other positron emitters in combination with a radioactive decay analysis. The size distribution for 11C-bearing aerosol particles was found to be ca. 70 μm in geometric mean diameter. The size was similar to that for 7Be-bearing particles obtained by a Ge detector measurement, and was slightly larger than the number-based size distribution measured with a scanning mobility particle sizer. The particle size measuring method using wire screens and imaging plates was successfully applied to the fine aerosol particles produced in an intense radiation field of a proton accelerator. This technique is applicable to size measurement of radioactive aerosol particles produced in the intense radiation fields of radiation facilities.

  16. 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

  17. Nano-sized calcium phosphate particles for periodontal gene therapy.

    Science.gov (United States)

    Elangovan, Satheesh; Jain, Shardool; Tsai, Pei-Chin; Margolis, Henry C; Amiji, Mansoor

    2013-01-01

    Growth factors such as platelet-derived growth factor (PDGF) have significantly enhanced periodontal therapy outcomes with a high degree of variability, mostly due to the lack of continual supply for a required period of time. One method to overcome this barrier is gene therapy. The aim of this in vitro study is to evaluate PDGF-B gene delivery in fibroblasts using nano-sized calcium phosphate particles (NCaPP) as vectors. NCaPP incorporating green fluorescent protein (NCaPP-GFP) and PDGF-B (NCaPP-PDGF-B) plasmids were synthesized using an established precipitation system and characterized using transmission electron microscopy and 1.2% agarose gel electrophoresis. Biocompatibility and transfection of the nanoplexes in fibroblasts were evaluated using cytotoxicity assay and florescence microscopy, respectively. Polymerase chain reaction and enzyme-linked immunosorbent assay were performed to evaluate PDGF-B transfection after different time points of treatments, and the functionality of PDGF-B transfection was evaluated using the cell proliferation assay. Synthesized NCaPP nanoplexes incorporating the genes of GFP and PDGF-B were spherical in shape and measured about 30 to 50 nm in diameter. Gel electrophoresis confirmed DNA incorporation and stability within the nanoplexes, and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium reagent assay demonstrated their biocompatibility in fibroblasts. In vitro transfection studies revealed a higher and longer lasting transfection after NCaPP-PDGF-B treatment, which lasted up to 96 hours. Significantly enhanced fibroblast proliferation observed in NCaPP-PDGF-B-treated cells confirmed the functionality of these nanoplexes. NCaPP demonstrated higher levels of biocompatibility and efficiently transfected PDGF plasmids into fibroblasts under described in vitro conditions.

  18. Verification of Gyrokinetic Particle of Turbulent Simulation of Device Size Scaling Transport

    Institute of Scientific and Technical Information of China (English)

    LIN Zhihong; S. ETHIER; T. S. HAHM; W. M. TANG

    2012-01-01

    Verification and historical perspective are presented on the gyrokinetic particle simulations that discovered the device size scaling of turbulent transport and indentified the geometry model as the source of the long-standing disagreement between gyrokinetic particle and continuum simulations.

  19. Data Descriptor : Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition

    NARCIS (Netherlands)

    Schmale, Julia; Henning, Silvia; Henzing, Bas; Keskinen, Helmi; Sellegri, Karine; Ovadnevaite, Jurgita; Bougiatioti, Aikaterini; Kalivitis, Nikos; Stavroulas, Iasonas; Jefferson, Anne; Park, Minsu; Schlag, Patrick; Kristensson, Adam; Iwamoto, Yoko; Pringle, Kirsty; Reddington, Carly; Aalto, Pasi; Äijälä, Mikko; Baltensperger, Urs; Bialek, Jakub; Birmili, Wolfram; Bukowiecki, Nicolas; Ehn, Mikael; Fjæraa, Ann Mari; Fiebig, Markus; Frank, Göran; Fröhlich, Roman; Frumau, Arnoud; Furuya, Masaki; Hammer, Emanuel; Heikkinen, Liine; Herrmann, Erik; Holzinger, Rupert; Hyono, Hiroyuki; Kanakidou, Maria; Kiendler-Scharr, Astrid; Kinouchi, Kento; Kos, Gerard P A; Kulmala, Markku; Mihalopoulos, Nikolaos; Motos, Ghislain; Nenes, Athanasios; O'Dowd, Colin; Paramonov, Mikhail; Petäjä, Tuukka; Picard, David; Poulain, Laurent; Prévôt, André Stephan Henry; Slowik, Jay; Sonntag, Andre; Swietlicki, Erik; Svenningsson, Birgitta; Tsurumaru, Hiroshi; Wiedensohler, Alfred; Wittbom, Cerina; Ogren, John A.; Matsuki, Atsushi; Yum, Seong Soo; Myhre, Cathrine Lund; Carslaw, Ken; Stratmann, Frank; Gysel, Martin

    2017-01-01

    Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other

  20. Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes

    Energy Technology Data Exchange (ETDEWEB)

    Dalmora, Adilson C. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração. Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Institute for Environmental Assessment and Water Studies (IDÆA), Spanish National Research Council (CSIC), C/Jordi Girona 18-26, 08034 Barcelona (Spain); Ramos, Claudete G.; Oliveira, Marcos L.S. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração. Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Teixeira, Elba C. [Fundação Estadual de Proteção Ambiental Henrique Luis Roessler, Porto Alegre, RS (Brazil); Kautzmann, Rubens M.; Taffarel, Silvio R. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração. Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Brum, Irineu A.S. de [Universidade Federal do Rio Grande do Sul, Escola de Engenharia, Departamento de Metalurgia, Centro de Tecnologia, Av. Bento Gonçalves, 9500. Bairro Agronomia. CEP: 91501-970 Porto Alegre, RS (Brazil); and others

    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 SiO{sub 2}, Al{sub 2}O{sub 3}, and Fe{sub 2}O{sub 3,} 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

  1. Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes

    International Nuclear Information System (INIS)

    Dalmora, Adilson C.; Ramos, Claudete G.; Oliveira, Marcos L.S.; Teixeira, Elba C.; Kautzmann, Rubens M.; Taffarel, Silvio R.; Brum, Irineu A.S. de

    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 SiO 2 , Al 2 O 3 , and Fe 2 O 3, 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

  2. Influence of particle size on physical and sensory attributes of mango pulp powder

    Science.gov (United States)

    Sharma, M.; Kadam, D. M.; Chadha, S.; Wilson, R. A.; Gupta, R. K.

    2013-09-01

    The present investigation was aimed to observe the effect of particle size on physical, sensory and thermal properties of foam-mat dried mango pulp powder. Mango pulp of Dussehri variety was foam-mat dried using 3% egg white at 65ºC. Dried foam-mats were pulverized and passed through a sieve shaker for obtaining three grades of powder with 50, 60, and 85 mesh size sieves. The particle size of these samples measured using laser diffraction particle size analyzer ranged from 191.26 to 296.19 μm. The data was analysed statistically using ANOVA of SAS. There was a linear increase in lightness (`L' value) with a decrease in particle size, however, `a' value decreased with a decrease in particle size, indicating the decrease in redness. An increase in bulk density and decrease in water solubility index and water absorption index % were observed with a decrease in particle size. Particle size had a significant effect on sensory parameters. Particle size in the range of 258.01 to 264.60μmwas found most acceptable with respect to sensory characteristics. This finding can be exploited for various commercial applicationswhere powder quality is dependent on the particle size and has foremost priority for end users.

  3. Optimizing the particle size of coal for CWM in view of fluidity. [Biomodal

    Energy Technology Data Exchange (ETDEWEB)

    Matsuo, Seiji; Nonaka, Michio; Okano, Yasuhiko; Inoue, Toshio

    1987-10-25

    As is well known, the viscosity of CWM is considerably influenced by the distribution of coal particle sizes and has bearing on particle packing density or porosity. A model for representing the viscosity of CWM in terms of particle porosity and specific surface was designed. Also, experimental verification was conducted for the method of optimizing particle size on a two-stage grinding system. The results are as follows: The viscosity of CWM is influenced not only by the porosity of coal particles, but also by the specific surface; also, it is correlated to the distance between suspended particles. At the two-stage grinding experiments, a particle size distribution leading to a low viscosity was obtained by mixing coarse and fine particles at 4:1. This has demonstrated that the use of an agitating mill for fine particles is of help. (11 figs, 2 tabs, 6 refs)

  4. Acceleration statistics of finite-sized particles in turbulent flow: the role of Faxen forces

    OpenAIRE

    Calzavarini, Enrico; Volk, Romain; Bourgoin, Mickael; Leveque, Emmanuel; Pinton, Jean-Francois; Toschi, Federico

    2008-01-01

    International audience; The dynamics of particles in turbulence when the particle size is larger than the dissipative scale of the carrier flow are studied. Recent experiments have highlighted signatures of particles' finiteness on their statistical properties, namely a decrease of their acceleration variance, an increase of correlation times (at increasing the particles size) and an independence of the probability density function of the acceleration once normalized to their variance. These ...

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

    International Nuclear Information System (INIS)

    Moreira, Edson G.; Vasconcellos, Marina B.A.; Santos, Rafaela G. dos; Martinelli, Jose R.

    2011-01-01

    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 μ = 94.6 ± 0.8 μm. (author)

  6. Ultrasound Assisted Particle Size Control by Continuous Seed Generation and Batch Growth

    OpenAIRE

    Jordens, Jeroen; Canini, Enio; Gielen, Bjorn; Van Gerven, Tom; Braeken, Leen

    2017-01-01

    Controlling particle size is essential for crystal quality in the chemical and pharmaceutical industry. Several articles illustrate the potential of ultrasound to tune this particle size during the crystallization process. This paper investigates how ultrasound can control the particle size distribution (PSD) of acetaminophen crystals by continuous seed generation in a tubular crystallizer followed by batch growth. It is demonstrated that the supersaturation ratio at which ultrasound starts s...

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

    International Nuclear Information System (INIS)

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

    2006-01-01

    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

  8. Chemical composition and source-apportionment of sub-micron particles during wintertime over Northern India: New insights on influence of fog-processing.

    Science.gov (United States)

    Rajput, Prashant; Singh, Dharmendra Kumar; Singh, Amit Kumar; Gupta, Tarun

    2018-02-01

    A comprehensive study was carried out from central part of Indo-Gangetic Plain (IGP; at Kanpur) to understand abundance, temporal variability, processes (secondary formation and fog-processing) and source-apportionment of PM 1 -bound species (PM 1 : particulate matter of aerodynamic diameter ≤ 1.0 μm) during wintertime. A total of 50 PM 1 samples were collected of which 33 samples represent submicron aerosol characteristics under non-foggy condition whereas 17 samples represent characteristics under thick foggy condition. PM 1 mass concentration during non-foggy episodes varied from 24-393 (Avg.: 247) μg m -3 , whereas during foggy condition it ranged from 42-243 (Avg.: 107) μg m -3 . With respect to non-foggy condition, the foggy conditions were associated with higher contribution of PM 1 -bound organic matter (OM, by 23%). However, lower fractional contribution of SO 4 2- , NO 3 - and NH 4 + during foggy conditions is attributable to wet-scavenging owing to their high affinity to water. Significant influence of fog-processing on organic aerosols composition is also reflected by co-enhancement in OC/EC and WSOC/OC ratio during foggy condition. A reduction by 5% in mineral dust fraction under foggy condition is associated with a parallel decrease in PM 1 mass concentration. However, mass fraction of elemental carbon (EC) looks quite similar (≈3% of PM 1 ) but the mass absorption efficiency (MAE) of EC is higher by 30% during foggy episodes. Thus, it is evident from this study that fog-processing leads to quite significant enhancement in OM (23%) contribution (and MAE of EC) with nearly equal and parallel decrease in SO 4 2- , NO 3 - and NH 4 + and mineral dust fractions (totaling to 24%). Characteristic features of mineral dust remain similar under foggy and non-foggy conditions; inferred from similar ratios of Fe/Al (≈0.3), Ca/Al (0.35) and Mg/Al (0.22). Positive matrix factorization (PMF) resolves seven sources: biomass burning (19.4%), coal combustion (1.1%), vehicular emission (3%), industrial activities (6.1%), leather tanneries (4%), secondary transformations (46.2%) and mineral dust (20.2%). Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Effect of Particle Size Distribution on Slurry Rheology: Nuclear Waste Simulant Slurries

    International Nuclear Information System (INIS)

    Chun, Jaehun; Oh, Takkeun; Luna, Maria L.; Schweiger, Michael J.

    2011-01-01

    Controlling the rheological properties of slurries has been of great interest in various industries such as cosmetics, ceramic processing, and nuclear waste treatment. Many physicochemical parameters, such as particle size, pH, ionic strength, and mass/volume fraction of particles, can influence the rheological properties of slurry. Among such parameters, the particle size distribution of slurry would be especially important for nuclear waste treatment because most nuclear waste slurries show a broad particle size distribution. We studied the rheological properties of several different low activity waste nuclear simulant slurries having different particle size distributions under high salt and high pH conditions. Using rheological and particle size analysis, it was found that the percentage of colloid-sized particles in slurry appears to be a key factor for rheological characteristics and the efficiency of rheological modifiers. This behavior was shown to be coupled with an existing electrostatic interaction between particles under a low salt concentration. Our study suggests that one may need to implement the particle size distribution as a critical factor to understand and control rheological properties in nuclear waste treatment plants, such as the U.S. Department of Energy's Hanford and Savannah River sites, because the particle size distributions significantly vary over different types of nuclear waste slurries.

  10. 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...

  11. Characterization of spherical core–shell particles by static light scattering. Estimation of the core- and particle-size distributions

    International Nuclear Information System (INIS)

    Clementi, Luis A.; Vega, Jorge R.; Gugliotta, Luis M.; Quirantes, Arturo

    2012-01-01

    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.

  12. On the functional form of particle number size distributions: influence of particle source and meteorological variables

    Science.gov (United States)

    Cugerone, Katia; De Michele, Carlo; Ghezzi, Antonio; Gianelle, Vorne; Gilardoni, Stefania

    2018-04-01

    Particle number size distributions (PNSDs) have been collected periodically in the urban area of Milan, Italy, during 2011 and 2012 in winter and summer months. Moreover, comparable PNSD measurements were carried out in the rural mountain site of Oga-San Colombano (2250 m a.s.l.), Italy, during February 2005 and August 2011. The aerosol data have been measured through the use of optical particle counters in the size range 0.3-25 µm, with a time resolution of 1 min. The comparison of the PNSDs collected in the two sites has been done in terms of total number concentration, showing higher numbers in Milan (often exceeding 103 cm-3 in winter season) compared to Oga-San Colombano (not greater than 2×102 cm-3), as expected. The skewness-kurtosis plane has been used in order to provide a synoptic view, and select the best distribution family describing the empirical PNSD pattern. The four-parameter Johnson system-bounded distribution (called Johnson SB or JSB) has been tested for this aim, due to its great flexibility and ability to assume different shapes. The PNSD pattern has been found to be generally invariant under site and season changes. Nevertheless, several PNSDs belonging to the Milan winter season (generally more than 30 %) clearly deviate from the standard empirical pattern. The seasonal increase in the concentration of primary aerosols due to combustion processes in winter and the influence of weather variables throughout the year, such as precipitation and wind speed, could be considered plausible explanations of PNSD dynamics.

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

    International Nuclear Information System (INIS)

    Tanaka, Toshihiro; Isfort, Peter; Braunschweig, Till; Westphal, Saskia; Woitok, Anna; Penzkofer, Tobias; Bruners, Philipp; Kichikawa, Kimihiko; Schmitz-Rode, Thomas; Mahnken, Andreas H.

    2013-01-01

    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.

  14. Effect of particle-size dynamics on properties of dense spongy-particle systems: Approach towards equilibrium

    Science.gov (United States)

    Zakhari, Monica E. A.; Anderson, Patrick D.; Hütter, Markus

    2017-07-01

    Open-porous deformable particles, often envisaged as sponges, are ubiquitous in biological and industrial systems (e.g., casein micelles in dairy products and microgels in cosmetics). The rich behavior of these suspensions is owing to the elasticity of the supporting network of the particle, and the viscosity of permeating solvent. Therefore, the rate-dependent size change of these particles depends on their structure, i.e., the permeability. This work aims at investigating the effect of the particle-size dynamics and the underlying particle structure, i.e., the particle permeability, on the transient and long-time behavior of suspensions of spongy particles in the absence of applied deformation, using the dynamic two-scale model developed by Hütter et al. [Farad. Discuss. 158, 407 (2012), 10.1039/c2fd20025b]. In the high-density limit, the transient behavior is found to be accelerated by the particle-size dynamics, even at average size changes as small as 1 % . The accelerated dynamics is evidenced by (i) the higher short-time diffusion coefficient as compared to elastic-particle systems and (ii) the accelerated formation of the stable fcc crystal structure. Furthermore, after long times, the particle-size dynamics of spongy particles is shown to result in lower stationary values of the energy and normal stresses as compared to elastic-particle systems. This dependence of the long-time behavior of these systems on the permeability, that essentially is a transport coefficient and hence must not affect the equilibrium properties, confirms that full equilibration has not been reached.

  15. Evaluation of instruments used in particle size analysis by using the sedimentation technique

    International Nuclear Information System (INIS)

    Elmasry, M.A.A.; Abdrahman, A.A.M.; Ahmed, A.Z.

    2007-01-01

    This study is carried out to evaluate the performance of some instruments in which the sedimentation technique is used for the determination of particle size distribution using Stoke's law. A mathematical formula has been developed to calculate the particle size distribution for different cases and the results were compared to the real ones. The results revealed unsatisfactory agreement between the calculated and the measured values. In addition, illogic results were obtained indicating that the instruments in which the sedimentation technique is used are not the proper ones to provide accurate measurements except for mono particle size cases. More above, the results obtained represent the sedimentation rate but not the particle size distribution.

  16. Polydisperse-particle-size-distribution function determined from intensity profile of angularly scattered light

    International Nuclear Information System (INIS)

    Alger, T.W.

    1979-01-01

    A new method for determining the particle-size-distribution function of a polydispersion of spherical particles is presented. The inversion technique for the particle-size-distribution function is based upon matching the measured intensity profile of angularly scattered light with a summation of the intensity contributions of a series of appropriately spaced, narrowband, size-distribution functions. A numerical optimization technique is used to determine the strengths of the individual bands that yield the best agreement with the measured scattered-light-intensity profile. Because Mie theory is used, the method is applicable to spherical particles of all sizes. Several numerical examples demonstrate the application of this inversion method

  17. The effects of particle size distribution and induced unpinning during grain growth

    International Nuclear Information System (INIS)

    Thompson, G.S.; Rickman, J.M.; Harmer, M.P.; Holm, E.A.

    1996-01-01

    The effect of a second-phase particle size distribution on grain boundary pinning was studied using a Monte Carlo simulation technique. Simulations were run using a constant number density of both whisker and rhombohedral particles, and the effect of size distribution was studied by varying the standard deviation of the distribution around a constant mean particle size. The results of present simulations indicate that, in accordance with the stereological assumption of the topological pinning model, changes in distribution width had no effect on the pinned grain size. The effect of induced unpinning of particles on microstructure was also studied. In contrast to predictions of the topological pinning model, a power law dependence of pinned grain size on particle size was observed at T=0.0. Based on this, a systematic deviation to the stereological predictions of the topological pinning model is observed. The results of simulations at higher temperatures indicate an increasing power law dependence of pinned grain size on particle size, with the slopes of the power law dependencies fitting an Arrhenius relation. The effect of induced unpinning of particles was also studied in order to obtain a correlation between particle/boundary concentration and equilibrium grain size. The results of simulations containing a constant number density of monosized rhombohedral particles suggest a strong power law correlation between the two parameters. copyright 1996 Materials Research Society

  18. Estimation of particle size distribution of nanoparticles from electrical ...

    Indian Academy of Sciences (India)

    2018-02-02

    Feb 2, 2018 ... An indirect method of estimation of size distribution of nanoparticles in a nanocomposite is ... The present approach exploits DC electrical current–voltage ... the sizes of nanoparticles (NPs) by electrical characterization.

  19. 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

    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...

  20. 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.

  1. Simultaneous velocity and particle size measurement in two phase flows by Laser Anemometry

    Science.gov (United States)

    Ungut, A.; Yule, A. J.; Taylor, D. S.; Chigier, N. A.

    1978-01-01

    A technique for particle size measurement by using Laser Doppler Anemometry is discussed. An additional gate photomultiplier has been introduced at right angles to the optical axis in order to select only those particles passing through the central region of the measurement control volume. Particle sizing measurements have been made in sprays of glass particles using the modified Laser Anemometry system. Measurements in fuel sprays are also reported and compared with the results obtained by a photographic technique. The application of the particle sizing technique to opaque particles is investigated and suitable optical arrangements are suggested. Light scattering characteristics of Laser Anemometry systems for different optical geometries are calculated to select the optimum optical arrangement for the particle sizing measurements.

  2. Particles size distribution effect on 3D packing of nanoparticles in to a bounded region

    International Nuclear Information System (INIS)

    Farzalipour Tabriz, M.; Salehpoor, P.; Esmaielzadeh Kandjani, A.; Vaezi, M. R.; Sadrnezhaad, S. K.

    2007-01-01

    In this paper, the effects of two different Particle Size Distributions on packing behavior of ideal rigid spherical nanoparticles using a novel packing model based on parallel algorithms have been reported. A mersenne twister algorithm was used to generate pseudo random numbers for the particles initial coordinates. Also, for this purpose a nano sized tetragonal confined container with a square floor (300 * 300 nm) were used in this work. The Andreasen and the Lognormal Particle Size Distributions were chosen to investigate the packing behavior in a 3D bounded region. The effects of particle numbers on packing behavior of these two Particle Size Distributions have been investigated. Also the reproducibility and the distribution of packing factor of these Particle Size Distributions were compared

  3. Size-selective separation of submicron particles in suspensions with ultrasonic atomization.

    Science.gov (United States)

    Nii, Susumu; Oka, Naoyoshi

    2014-11-01

    Aqueous suspensions containing silica or polystyrene latex were ultrasonically atomized for separating particles of a specific size. With the help of a fog involving fine liquid droplets with a narrow size distribution, submicron particles in a limited size-range were successfully separated from suspensions. Performance of the separation was characterized by analyzing the size and the concentration of collected particles with a high resolution method. Irradiation of 2.4MHz ultrasound to sample suspensions allowed the separation of particles of specific size from 90 to 320nm without regarding the type of material. Addition of a small amount of nonionic surfactant, PONPE20 to SiO2 suspensions enhanced the collection of finer particles, and achieved a remarkable increase in the number of collected particles. Degassing of the sample suspension resulted in eliminating the separation performance. Dissolved air in suspensions plays an important role in this separation. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Effects of fuel particle size distributions on neutron transport in stochastic media

    International Nuclear Information System (INIS)

    Liang, Chao; Pavlou, Andrew T.; Ji, Wei

    2014-01-01

    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 (k eff ) 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

  5. 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

    2017-09-12

    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.

  6. Particle Sampling and Real Time Size Distribution Measurement in H2/O2/TEOS Diffusion Flame

    International Nuclear Information System (INIS)

    Ahn, K.H.; Jung, C.H.; Choi, M.; Lee, J.S.

    2001-01-01

    Growth characteristics of silica particles have been studied experimentally using in situ particle sampling technique from H 2 /O 2 /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

  7. Effects of various forces on the distribution of particles at the boundary of a dusty plasma

    International Nuclear Information System (INIS)

    Liu, J.; Ma, J.X.

    1997-01-01

    The distribution and suspension of dust particles under the action of electrostatic, gravitational, ion-drag and neutral collision forces are investigated near the boundary of a dusty plasma. It is shown that the competition among the forces results in spatial oscillations (multi-layer) of the particle distribution. For sub-micron grains the ion-drag has a significant effect on the grain dynamics while for micrometer sized grains the gravity quickly dominates over other forces. The effect of the neutral gas flux is to enhance or diminish that of the gravity while the effect of the neutral viscosity is to shift the profile toward the wall. Under the force balance, the particles are suspended in a narrow region with sharp boundaries within the sheath. copyright 1997 American Institute of Physics

  8. Hydrodynamics of multi-sized particles in stable regime of a swirling bed

    Energy Technology Data Exchange (ETDEWEB)

    Miin, Chin Swee; Sulaiman, Shaharin Anwar; Raghavan, Vijay Raj; Heikal, Morgan Raymond; Naz, Muhammad Yasin [Universiti Teknologi PETRONAS, Perak (Malaysia)

    2015-11-15

    Using particle imaging velocimetry (PIV), we observed particle motion within the stable operating regime of a swirling fluidized bed with an annular blade distributor. This paper presents velocity profiles of particle flow in an effort to determine effects from blade angle, particle size and shape and bed weight on characteristics of a swirling fluidized bed. Generally, particle velocity increased with airflow rate and shallow bed height, but decreased with bed weight. A 3 .deg. increase in blade angle reduced particle velocity by approximately 18%. In addition, particle shape, size and bed weight affected various characteristics of the swirling regime. Swirling began soon after incipience in the form of a supra-linear curve, which is the characteristic of a swirling regime. The relationship between particle and gas velocities enabled us to predict heat and mass transfer rates between gas and particles.

  9. 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.

  10. 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.

  11. Effect of particle size on microstructure and mechanical properties of composites produced by ARB process

    International Nuclear Information System (INIS)

    Jamaati, Roohollah; Amirkhanlou, Sajjad; Toroghinejad, Mohammad Reza; Niroumand, Behzad

    2011-01-01

    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.

  12. Method for rapid particle size analysis by hydrosizing and nuclear sensing

    International Nuclear Information System (INIS)

    Daellenbach, C.B.; Mahan, W.M.

    1977-01-01

    A method and apparatus to practice the method for rapidly determining the size and mass distribution of a sample of randomly sized particles of a known total mass are described. A series of substantially identical hydrocyclones are connected by conduits to each other and to a temperature controlled water feed. By restricting the cross-sectional areas of these conduits to progressively smaller values, the slurry containing the sample particles is caused to increase its velocity as it moves from hydrocyclone to hydrocyclone. As described by the Stokesian theory which relates particle diameter and settling velocity, the largest sized particles are suspended in the closed apex of the first hydrocyclone with smaller sized particles, in given size ranges, being suspended in the next succeeding hydrocyclone's apexes. In this manner, the particles are separated into discrete fractional sizes with a residual slurry of the very smallest particles being discharged. Before the discrete fractions of particles are suspended in their hydrocyclone apexes, a combined photon source, like a gamma ray source, and detector are calibrated with the water temperature kept constant. When the suspension of particles takes place, an attenuation of the radiation from the source is observed at the detector. This attenuation can be related to the mass or weight of the discrete fractions of suspended particles. Electronic circuitry is used to indicate what this fractional mass or weight is as it relates to the total weight of the sample. 6 claims, 4 figs

  13. Effect of particle size on laser-induced breakdown spectroscopy analysis of alumina suspension in liquids

    International Nuclear Information System (INIS)

    Diaz Rosado, José Carlos; L'hermite, Daniel; Levi, Yves

    2012-01-01

    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 Al 2 O 3 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 Al 2 O 3 particles in suspension in water has been estimated. ► We can determine the deepness of the interaction volume into the liquid.

  14. Viscous properties of ferrofluids containing both micrometer-size magnetic particles and fine needle-like particles

    Energy Technology Data Exchange (ETDEWEB)

    Ido, Yasushi, E-mail: ido.yasushi@nitech.ac.jp [Department of Electric and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya (Japan); Nishida, Hitoshi [Department of Electrical and Control Systems Engineering, National Institute of Technology, Toyama College, 13 Hongo-cho, Toyama (Japan); Iwamoto, Yuhiro [Department of Electric and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya (Japan); Yokoyama, Hiroki [KYB Corporation, 2-4-1 Hamamatsu-cho, Minato-ku, Tokyo (Japan)

    2017-06-01

    Ferrofluids containing both micrometer-size spherical magnetic particles and nanometer-size needle-like nonmagnetic hematite particles were newly produced. Average length of long axis of the needle-like nonmagnetic particles was 194 nm and the aspect ratio was 8.3. Shear stress and viscosity were measured using the rheometer with the additional equipment for viscosity measurements in the presence of magnetic field. When the total volume fraction of particles in the fluid is constant (0.30), there is the specific mixing ratio of the particles to increase viscosity of the fluid drastically in the absence of magnetic field due to the percolation phenomenon. The fluid of the specific mixing ratio shows solid-like behavior even in the absence of magnetic field. Mixing the needle-like nonmagnetic particles causes strong yield stress and strong viscous force in the presence of magnetic field. - Highlights: • Viscous properties of new magnetic functional fluids were studied experimentally. • The new fluids contain spherical magnetic particles and needle-like particles. • Percolation occurs in the fluid of specific mixing ratio of particles without field. • The fluid of the specific mixing ratio behaves like solid without field. • Mixing needle-like particles causes strong yield stress of the fluid in the field.

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

    Science.gov (United States)

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

    2013-04-01

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

  16. Effect of particle size of granules on some mechanical properties of ...

    African Journals Online (AJOL)

    Solid dosage forms are invariably multiparticulate systems of heterogenous particle size distribution. The purpose of this study was to investigate the effect of particle size distribution of paracetamol granules on some tablet mechanical properties of paracetamol tablets. Granules were formed by wet massing paracetamol ...

  17. On the origin of the cobalt particle size effects in Fischer−Tropsch catalysis

    NARCIS (Netherlands)

    den Breejen, J.P.|info:eu-repo/dai/nl/304837318; Radstake, P.B.|info:eu-repo/dai/nl/304829587; Bezemer, G.L.; Bitter, J.H.|info:eu-repo/dai/nl/160581435; Froseth, V.; Holmen, A.; de Jong, K.P.|info:eu-repo/dai/nl/06885580X

    2009-01-01

    The effects of metal particle size in catalysis are of prime scientific and industrial importance and call for a better understanding. In this paper the origin of the cobalt particle size effects in Fischer−Tropsch (FT) catalysis was studied. Steady-State Isotopic Transient Kinetic Analysis (SSITKA)

  18. Evaluation of radiocolloids as thrombus imaging agents. Effect of particle size on thrombus uptake

    Energy Technology Data Exchange (ETDEWEB)

    Rosenthal, S.N.; Bardfeld, P.A.

    1985-01-01

    Thrombus uptake values of several /sup 99m/Tc labeled radiocolloids determined using an experimental rodent model of deep venous thrombosis were correlated with particle size distributions. The thrombus uptake values increased with increasing mean particle size. The /sup 99m/Tc-tin colloid had the highest thrombus uptake value of any of the colloids used in this study.

  19. Particle size distribution of hydrocyanic acid in gari, a cassava-based product.

    Science.gov (United States)

    Maduagwu, E N; Fafunso, M

    1980-12-01

    A reciprocal relationship was observed between the cyanide content of gari and particle size. Hydrocyanic acid (HCN) content was positively correlated (r = 0.62) with sugar content but the correlation with starch content was poor (r = 0.33). From both the nutritional and toxicological standpoints, it would appear that larger particles size in gari is beneficial.

  20. Sub-micron indent induced plastic deformation in copper and irradiated steel; Deformation plastique induite par l'essai d'indentation submicronique, dans le cuivre et l'acier 316L irradie

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Ch

    1999-07-01

    In this work we aim to study the indent induced plastic deformation. For this purpose, we have developed a new approach, whereby the indentation curves provides the mechanical behaviour, while the deformation mechanisms are observed thanks to Transmission Electron Microscopy (TEM). In order to better understand how an indent induced dislocation microstructure forms, numerical modeling of the indentation process at the scale of discrete dislocations has been worked out as well. Validation of this modeling has been performed through direct comparison of the computed microstructures with TEM micrographs of actual indents in pure Cu (001]. Irradiation induced modifications of mechanical behaviour of ion irradiated 316L have been investigated, thanks to the mentioned approach. An important hardening effect was reported from indentation data (about 50%), on helium irradiated 316L steel. TEM observations of the damage zone clearly show that this behaviour is associated with the presence of He bubbles. TEM observations of the indent induced plastic zone also showed that the extent of the plastic zone is strongly correlated with hardness, that is to say: harder materials gets a smaller plastic zone. These results thus clearly established that the selected procedure can reveal any irradiation induced hardening in sub-micron thick ion irradiated layers. The behaviour of krypton irradiated 316L steel is somewhat more puzzling. In one hand indeed, a strong correlation between the defect cluster size and densities on the irradiation temperature is observed in the 350 deg. C - 600 deg. C range, thanks to TEM observations of the damage zone. On the other hand, irradiation induced hardening reported from indentation data is relatively small (about 10%) and shows no dependence upon the irradiation temperature (within the mentioned range). In addition, it has been shown that the reported hardening vanishes following appropriate post-irradiation annealing, although most of the TEM

  1. Study on effective particle diameters and coolability of particulate beds packed with irregular multi-size particles

    Energy Technology Data Exchange (ETDEWEB)

    Thakre, S.; Ma, W.; Kudinov, P.; Bechta, S. [Royal Institute of Technology, KTH. Div. of Nuclear Power Safety, Stockholm (Sweden)

    2013-08-15

    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

  2. Study on effective particle diameters and coolability of particulate beds packed with irregular multi-size particles

    International Nuclear Information System (INIS)

    Thakre, S.; Ma, W.; Kudinov, P.; Bechta, S.

    2013-08-01

    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

  3. Surface modification and particles size distribution control in nano-CdS/polystyrene composite film

    International Nuclear Information System (INIS)

    Min Zhirong; Ming Qiuzhang; Hai Chunliang; Han Minzeng

    2003-01-01

    Preparation of nano-CdS particles with surface thiol modification by microemulsion method and their influences on the particle size distribution in highly filled polystyrene-based composites were studied. The modified nano-CdS was characterized by X-ray photoelectron spectroscopy (XPS), light absorption and emission measurements to reveal the morphologies of the surface modifier, which are consistent with the surface molecules packing calculation. The morphologies of the surface modifier exerted a great influence not only on the optical performance of the particles themselves, but also on the size distribution of the particle in polystyrene matrix. A monolayer coverage with tightly packed thiol molecules was believed to be most effective in promoting a uniform particle size distribution and eliminating the surface defects that cause radiationless recombination. Control of the particles size distribution in polystyrene can be attained by adjusting surface coverage status of the thiol molecules based on the strong interaction between the surface modifier and the matrix

  4. Determination of the particle size distribution of aerosols by means of a diffusion battery

    International Nuclear Information System (INIS)

    Maigne, J.P.

    1978-09-01

    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 [fr

  5. Clearance of iron oxide particles in rat liver: effect of hydrated particle size and coating material on liver metabolism.

    Science.gov (United States)

    Briley-Saebo, Karen C; Johansson, Lars O; Hustvedt, Svein Olaf; Haldorsen, Anita G; Bjørnerud, Atle; Fayad, Zahi A; Ahlstrom, Haakan K

    2006-07-01

    We sought to evaluate the effect of the particle size and coating material of various iron oxide preparations on the rate of rat liver clearance. The following iron oxide formulations were used in this study: dextran-coated ferumoxide (size = 97 nm) and ferumoxtran-10 (size = 21 nm), carboxydextran-coated SHU555A (size = 69 nm) and fractionated SHU555A (size = 12 nm), and oxidized-starch coated materials either unformulated NC100150 (size = 15 nm) or formulated NC100150 injection (size = 12 nm). All formulations were administered to 165 rats at 2 dose levels. Quantitative liver R2* values were obtained during a 63-day time period. The concentration of iron oxide particles in the liver was determined by relaxometry, and these values were used to calculate the particle half-lives in the liver. After the administration of a high dose of iron oxide, the half-life of iron oxide particles in rat liver was 8 days for dextran-coated materials, 10 days for carboxydextran materials, 14 days for unformulated oxidized-starch, and 29 days for formulated oxidized-starch. The results of the study indicate that materials with similar coating but different sizes exhibited similar rates of liver clearance. It was, therefore, concluded that the coating material significantly influences the rate of iron oxide clearance in rat liver.

  6. Fabrication, Characterization, and Biological Activity of Avermectin Nano-delivery Systems with Different Particle Sizes

    Science.gov (United States)

    Wang, Anqi; Wang, Yan; Sun, Changjiao; Wang, Chunxin; Cui, Bo; Zhao, Xiang; Zeng, Zhanghua; Yao, Junwei; Yang, Dongsheng; Liu, Guoqiang; Cui, Haixin

    2018-01-01

    Nano-delivery systems for the active ingredients of pesticides can improve the utilization rates of pesticides and prolong their control effects. This is due to the nanocarrier envelope and controlled release function. However, particles containing active ingredients in controlled release pesticide formulations are generally large and have wide size distributions. There have been limited studies about the effect of particle size on the controlled release properties and biological activities of pesticide delivery systems. In the current study, avermectin (Av) nano-delivery systems were constructed with different particle sizes and their performances were evaluated. The Av release rate in the nano-delivery system could be effectively controlled by changing the particle size. The biological activity increased with decreasing particle size. These results suggest that Av nano-delivery systems can significantly improve the controllable release, photostability, and biological activity, which will improve efficiency and reduce pesticide residues.

  7. 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.

  8. Particle Size Control for PIV Seeding Using Dry Ice

    Science.gov (United States)

    2010-03-01

    in flight actually being carried out, the observations, drawings and notes of Leonardo da Vinci showed an analytical process to develop a way for...theoretical particle response: dvp dt = −C(vp − U) C = 18µ ρpd2p 86 87 Bibliography 1. Linscott, R. N. and Da Vinci , L., The Notebooks of Leonardo Da Vinci

  9. Micrometer-scale 3-D shape characterization of eight cements: Particle shape and cement chemistry, and the effect of particle shape on laser diffraction particle size measurement

    International Nuclear Information System (INIS)

    Erdogan, S.T.; Nie, X.; Stutzman, P.E.; Garboczi, E.J.

    2010-01-01

    Eight different portland cements were imaged on a synchrotron beam line at Brookhaven National Laboratory using X-ray microcomputed tomography at a voxel size of about 1 μm per cubic voxel edge. The particles ranged in size roughly between 10 μm and 100 μm. The shape and size of individual particles were computationally analyzed using spherical harmonic analysis. The particle shape difference between cements was small but significant, as judged by several different quantitative shape measures, including the particle length, width, and thickness distributions. It was found that the average shape of cement particles was closely correlated with the volume fraction of C 3 S (alite) and C 2 S (belite) making up the cement powder. It is shown that the non-spherical particle shape of the cements strongly influence laser diffraction results, at least in the sieve size range of 20 μm to 38 μm. Since laser diffraction particle size measurement is being increasingly used by the cement industry, while cement chemistry is always a main factor in cement production, these results could have important implications for how this kind of particle size measurement should be understood and used in the cement industry.

  10. The effect of particle shape and size distribution on the acoustical properties of mixtures of hemp particles.

    Science.gov (United States)

    Glé, Philippe; Gourdon, Emmanuel; Arnaud, Laurent; Horoshenkov, Kirill-V; Khan, Amir

    2013-12-01

    Hemp concrete is an attractive alternative to traditional materials used in building construction. It has a very low environmental impact, and it is characterized by high thermal insulation. Hemp aggregate particles are parallelepiped in shape and can be organized in a plurality of ways to create a considerable proportion of open pores with a complex connectivity pattern, the acoustical properties of which have never been examined systematically. Therefore this paper is focused on the fundamental understanding of the relations between the particle shape and size distribution, pore size distribution, and the acoustical properties of the resultant porous material mixture. The sound absorption and the transmission loss of various hemp aggregates is characterized using laboratory experiments and three theoretical models. These models are used to relate the particle size distribution to the pore size distribution. It is shown that the shape of particles and particle size control the pore size distribution and tortuosity in shiv. These properties in turn relate directly to the observed acoustical behavior.

  11. On airborne nano/micro-sized wear particles released from low-metallic automotive brakes

    International Nuclear Information System (INIS)

    Kukutschova, Jana; Moravec, Pavel; Tomasek, Vladimir; Matejka, Vlastimil; Smolik, Jiri; Schwarz, Jaroslav; Seidlerova, Jana; Safarova, Klara; Filip, Peter

    2011-01-01

    The paper addresses the wear particles released from commercially available 'low-metallic' automotive brake pads subjected to brake dynamometer tests. Particle size distribution was measured in situ and the generated particles were collected. The collected fractions and the original bulk material were analyzed using several chemical and microscopic techniques. The experiments demonstrated that airborne wear particles with sizes between 10 nm and 20 μm were released into the air. The numbers of nanoparticles (<100 nm) were by three orders of magnitude larger when compared to the microparticles. A significant release of nanoparticles was measured when the average temperature of the rotor reached 300 deg. C, the combustion initiation temperature of organics present in brakes. In contrast to particle size distribution data, the microscopic analysis revealed the presence of nanoparticles, mostly in the form of agglomerates, in all captured fractions. The majority of elements present in the bulk material were also detected in the ultra-fine fraction of the wear particles. - Research highlights: → Wear of low-metallic friction composite produces airborne nano-sized particles. → Nano-sized particles contain carbon black and metallic compounds. → Carbon black nano-sized particles are related to resin degradation. → Number of nanoparticles higher by three orders of magnitude than microparticles. - Braking of automobiles may contribute to nano-particulate air pollution caused by friction processes associated with wear of low-metallic brake pads.

  12. Size limits for rounding of volcanic ash particles heated by lightning

    Science.gov (United States)

    Wadsworth, Fabian B.; Vasseur, Jérémie; Llewellin, Edward W.; Genareau, Kimberly; Cimarelli, Corrado; Dingwell, Donald B.

    2017-03-01

    Volcanic ash particles can be remelted by the high temperatures induced in volcanic lightning discharges. The molten particles can round under surface tension then quench to produce glass spheres. Melting and rounding timescales for volcanic materials are strongly dependent on heating duration and peak temperature and are shorter for small particles than for large particles. Therefore, the size distribution of glass spheres recovered from ash deposits potentially record the short duration, high-temperature conditions of volcanic lightning discharges, which are hard to measure directly. We use a 1-D numerical solution to the heat equation to determine the timescales of heating and cooling of volcanic particles during and after rapid heating and compare these with the capillary timescale for rounding an angular particle. We define dimensionless parameters—capillary, Fourier, Stark, Biot, and Peclet numbers—to characterize the competition between heat transfer within the particle, heat transfer at the particle rim, and capillary motion, for particles of different sizes. We apply this framework to the lightning case and constrain a maximum size for ash particles susceptible to surface tension-driven rounding, as a function of lightning temperature and duration, and ash properties. The size limit agrees well with maximum sizes of glass spheres found in volcanic ash that has been subjected to lightning or experimental discharges, demonstrating that the approach that we develop can be used to obtain a first-order estimate of lightning conditions in volcanic plumes.

  13. Accurate particle speed prediction by improved particle speed measurement and 3-dimensional particle size and shape characterization technique

    DEFF Research Database (Denmark)

    Cernuschi, Federico; Rothleitner, Christian; Clausen, Sønnik

    2017-01-01

    Accurate particle mass and velocity measurement is needed for interpreting test results in erosion tests of materials and coatings. The impact and damage of a surface is influenced by the kinetic energy of a particle, i.e. particle mass and velocity. Particle mass is usually determined with optic...

  14. Influence of Particle Size in Talc Suppression by a Galactomannan Depressant

    Directory of Open Access Journals (Sweden)

    Zhixiang Chen

    2018-03-01

    Full Text Available Flotation behavior of different sizes of particles may follow different trends. The influence of particle size in talc suppression by a depressant galactomannan was studied in this research. The flotation response and mechanism were examined by flotation tests, modified flotation rate constant and entrainment recovery calculation, laser particle size experiments, adsorption tests, and advancing contact angle measurement as well as scanning electron microscopy (SEM and energy dispersive X-ray spectrometry (EDS. The maximum recovery increased with particle size increases in the absence of galactomannan FPY (Fenugreek polysaccharide. The obviously suppressed effect was observed for the size fraction of −74 + 38 μm after reacting with FPY, but low efficiency was received for −38 μm and −10 μm, respectively. Laser particle size analysis indicated that the FPY has a certain function for the flocculation of fine particles. It is beneficial for reducing recovery by entrainment. EDS and advancing contact angle test results showed that the difference in contact angles probably is a result of genuine differences in the quantity of O and Mg bearing surface species, while the contact angle varied with particle size fraction in the absence of FPY. Adsorption and SEM test results demonstrated that in the case of −74 + 38 μm, the depressant adsorption density on the mineral surface is higher than the other two size fractions. On the whole, FPY probably is not enough of a depressant for talc suppression.

  15. 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

  16. Particle size distribution and physico-chemical composition of clay.

    African Journals Online (AJOL)

    HP USER

    <300µm, <106µm, <63µm and <44µm respectively. There was no remarkable difference in silica (SiO2) as particle fractions reduced from <. 300µm - < 106µm - < 63µm but an observed. Table 1.0 Chemical composition of crude clay. Component wt (%). SiO2. 38.48. Al2O3. 12.46. Fe2O3. 6.18. TiO2. 1.85. MgO. 14.67. CaO.

  17. Investigation of Composition of Particle Size in Sediments of Stormwater Sedimentation Tank

    OpenAIRE

    Daiva Laučytė; Regimantas Dauknys

    2011-01-01

    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 ...

  18. 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.

  19. The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes

    International Nuclear Information System (INIS)

    Zhang, Bo; Edwards, Brian J.

    2015-01-01

    A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated with the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes

  20. The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes.

    Science.gov (United States)

    Zhang, Bo; Edwards, Brian J

    2015-06-07

    A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated with the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes.

  1. Particle diffusional layer thickness in a USP dissolution apparatus II: a combined function of particle size and paddle speed.

    Science.gov (United States)

    Sheng, Jennifer J; Sirois, Paul J; Dressman, Jennifer B; Amidon, Gordon L

    2008-11-01

    This work was to investigate the effects of particle size and paddle speed on the particle diffusional layer thickness h(app) in a USP dissolution apparatus II. After the determination of the powder dissolution rates of five size fractions of fenofibrate, including <20, 20-32, 32-45, 63-75, and 90-106 microm, the present work shows that the dependence of h(app) on particle size follows different functions in accordance with the paddle speed. At 50 rpm, the function of h(app) is best described by a linear plot of h{app} = 9.91sqrt d-23.31 (R(2) = 0.98) throughout the particle diameter, d, from 6.8 to 106 microm. In contrast, at 100 rpm a transitional particle radius, r, of 23.7 microm exists, under which linear relationship h(app) = 1.59r (R(2) = 0.98) occurs, but above which h(app) becomes a constant of 43.5 microm. Thus, h(app) changes not only with particle size, but also with the hydrodynamics under standard USP configurations, which has been overlooked in the past. Further, the effects of particle size and paddle speed on h(app) were combined using dimensionless analysis. Within certain fluid velocity/particle regime, linear correlation of h(app)/d with the square-root of Reynolds number (d\\varpi/upsilon){1/2}, that is, h{app}/d = 1.5207 - 9.25 x 10{- 4} (d\\varpi/n){1/2} (R(2) = 0.9875), was observed.

  2. Particle size reduction in debris flows: Laboratory experiments compared with field data from Inyo Creek, California

    Science.gov (United States)

    Arabnia, O.; Sklar, L. S.; Mclaughlin, M. K.

    2014-12-01

    Rock particles in debris flows are reduced in size through abrasion and fracture. Wear of coarse sediments results in production of finer particles, which alter the bulk material rheology and influence flow dynamics and runout distance. Particle wear also affects the size distribution of coarse particles, transforming the initial sediment size distribution produced on hillslopes into that delivered to the fluvial channel network. A better understanding of the controls on particle wear in debris flows would aid in the inferring flow conditions from debris flow deposits, in estimating the initial size of sediments entrained in the flow, and in modeling debris flow dynamics and mapping hazards. The rate of particle size reduction with distance traveled should depend on the intensity of particle interactions with other particles and the flow boundary, and on rock resistance to wear. We seek a geomorphic transport law to predict rate of particle wear with debris flow travel distance as a function of particle size distribution, flow depth, channel slope, fluid composition and rock strength. Here we use four rotating drums to create laboratory debris flows across a range of scales. Drum diameters range from 0.2 to 4.0 m, with the largest drum able to accommodate up to 2 Mg of material, including boulders. Each drum has vanes along the boundary to prevent sliding. Initial experiments use angular clasts of durable granodiorite; later experiments will use less resistant rock types. Shear rate is varied by changing drum rotational velocity. We begin experiments with well-sorted coarse particle size distributions, which are allowed to evolve through particle wear. The fluid is initially clear water, which rapidly acquires fine-grained wear products. After each travel increment all coarse particles (mass > 0.4 g) are weighed individually. We quantify particle wear rates using statistics of size and mass distributions, and by fitting various comminution functions to the data

  3. Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens

    Science.gov (United States)

    Cicek, Ahmet; Korozlu, Nurettin; Adem Kaya, Olgun; Ulug, Bulent

    2017-03-01

    We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated.

  4. Particle size distribution measurements of radionuclides from Chernobyl

    International Nuclear Information System (INIS)

    Georgi, B.; Tschiersch, J.

    1988-01-01

    Characteristics of the size distribution of the Chernobyl aerosol have been measured at four locations along the trajectory of the cloud. Changes in time and differences between 131 I and the other isotopes are explained by aerosol physical processes. The relevance of the measurements for dose calculations are discussed

  5. The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size.

    Science.gov (United States)

    Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech

    2016-04-20

    Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of -0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

  6. The effect of particle size on sorption of estrogens, androgens and progestagens in aquatic sediment

    International Nuclear Information System (INIS)

    Sangster, Jodi L.; Oke, Hugues; Zhang, Yun; Bartelt-Hunt, Shannon L.

    2015-01-01

    Highlights: • Two sediments were used to evaluate the effects of particle size on steroid sorption. • Sorption capacity did not increase with decreasing particle size for all steroids. • Particle interactions affect the distribution of steroids within the whole sediments. • Preferential sorption to fine particles was observed. - Abstract: There is growing concern about the biologic effects of steroid hormones in impacted waterways. There is increasing evidence of enhanced transport and biological effects stemming from steroid hormones associated with soils or sediments; however, there are limited studies evaluating how steroid hormone distribution between various particle sizes within whole sediments affects steroid fate. In this study, sorption of 17β-estradiol, estrone, progesterone, and testosterone was evaluated to different size fractions of two natural sediments, a silty loam and a sandy sediment, to determine the steroid sorption capacity to each fraction and distribution within the whole sediment. Sorption isotherms for all steroid hormones fit linear sorption models. Sorption capacity was influenced more by organic carbon content than particle size. Interactions between size fractions were found to affect the distribution of steroids within the whole sediments. All four steroids preferentially sorbed to the clay and colloids in the silty loam sediment at the lowest aqueous concentration (1 ng/L) and as aqueous concentration increased, the distribution of sorbed steroid was similar to the distribution by weight of each size fraction within the whole sediment. In the sandy sediment, preferential sorption to fine particles was observed.

  7. The effect of particle size on sorption of estrogens, androgens and progestagens in aquatic sediment

    Energy Technology Data Exchange (ETDEWEB)

    Sangster, Jodi L.; Oke, Hugues; Zhang, Yun; Bartelt-Hunt, Shannon L., E-mail: sbartelt2@unl.edu

    2015-12-15

    Highlights: • Two sediments were used to evaluate the effects of particle size on steroid sorption. • Sorption capacity did not increase with decreasing particle size for all steroids. • Particle interactions affect the distribution of steroids within the whole sediments. • Preferential sorption to fine particles was observed. - Abstract: There is growing concern about the biologic effects of steroid hormones in impacted waterways. There is increasing evidence of enhanced transport and biological effects stemming from steroid hormones associated with soils or sediments; however, there are limited studies evaluating how steroid hormone distribution between various particle sizes within whole sediments affects steroid fate. In this study, sorption of 17β-estradiol, estrone, progesterone, and testosterone was evaluated to different size fractions of two natural sediments, a silty loam and a sandy sediment, to determine the steroid sorption capacity to each fraction and distribution within the whole sediment. Sorption isotherms for all steroid hormones fit linear sorption models. Sorption capacity was influenced more by organic carbon content than particle size. Interactions between size fractions were found to affect the distribution of steroids within the whole sediments. All four steroids preferentially sorbed to the clay and colloids in the silty loam sediment at the lowest aqueous concentration (1 ng/L) and as aqueous concentration increased, the distribution of sorbed steroid was similar to the distribution by weight of each size fraction within the whole sediment. In the sandy sediment, preferential sorption to fine particles was observed.

  8. Experimental investigation of particle size distribution influence on diffusion controlled coarsening

    International Nuclear Information System (INIS)

    Fang, Zhigang; Patterson, B.R.

    1993-01-01

    The influence of initial particle size distribution on coarsening during liquid phase sintering has been experimentally investigated using W-14Ni-6Fe alloy as a model system. It was found that initially wider size distribution particles coarsened more rapidly than those of an initially narrow distribution. The well known linear relationship between the cube of the average particle radius bar r -3 , and time was observed for most of the coarsening process, although the early stage coarsening rate constant changed with time, as expected with concomitant early changes in the tungsten particle size distribution. The instantaneous transient rate constant was shown to be related to the geometric standard deviation, 1nσ, of the instantaneous size distributions, with higher rate constants corresponding to larger 1nσ values. The form of the particle size distributions changed rapidly during early coarsening and reached a quasi-stable state, different from the theoretical asymptotic distribution, after some time. A linear relationship was found between the experimentally observed instantaneous rate constant and that computed from an earlier model incorporating the effect of particle size distribution. The above results compare favorably with those from prior theoretical modeling and computer simulation studies of the effect of particle size distribution on coarsening, based on the DeHoff communicating neighbor model

  9. A novel approach for preparation of micrometer-sized, monodisperse dimple and hemispherical polystyrene particles.

    Science.gov (United States)

    Tanaka, Takuya; Komatsu, Yoshifumi; Fujibayashi, Teruhisa; Minami, Hideto; Okubo, Masayoshi

    2010-03-16

    Micrometer-sized, monodisperse dimple and hemispherical polystyrene (PS) particles were successfully prepared by heating (55-70 degrees C) of spherical PS particles dispersed in methanol/water media (40/60 to 80/20, w/w) in the presence of decane droplets, and subsequent cooling down to room temperature. Decane was absorbed by the PS particles during the heating process. Decane-absorbed PS particles phase-separated into PS and decane phases in the inside during the cooling process, and eventually dimple and/or hemispherical particles were formed by removal of the decane phase from phase-separated PS/decane particles by evaporation. The size of the dimple, which is determined by the volume of decane phase-separated from decane-absorbed PS particles during the cooling process, increased with increases in the heating temperature and the methanol content.

  10. Effect of dispersed phase particle size on microstructure of cup fracture

    International Nuclear Information System (INIS)

    Goritskij, V.M.; Guseva, I.A.

    1978-01-01

    A correlation-regressive analysis has been carried out to reveal the influence of the size and the mean distance between the disperse particles of deposits V(C,N) on the microstructure (size of micropores and cups, density of the cups) of a viscous cup-like fracture of specimens made of 30Kh2NMFA grade steel that has been hardened and annealed. It is shown that micropores develop at relatively large particles of deposits V(C,N) (>=0.04/m). A strong correlation linear connection exists between the size of a disperse particle of deposits V(C,N), the size of micropore and cup. This connection is attributable to the close, pairwise correlative connection between the size of the particle and the micropore, the micropore and the cup

  11. Feed particle size evaluation: conventional approach versus digital holography based image analysis

    Directory of Open Access Journals (Sweden)

    Vittorio Dell’Orto

    2010-01-01

    Full Text Available The aim of this study was to evaluate the application of image analysis approach based on digital holography in defining particle size in comparison with the sieve shaker method (sieving method as reference method. For this purpose ground corn meal was analyzed by a sieve shaker Retsch VS 1000 and by image analysis approach based on digital holography. Particle size from digital holography were compared with results obtained by screen (sieving analysis for each of size classes by a cumulative distribution plot. Comparison between particle size values obtained by sieving method and image analysis indicated that values were comparable in term of particle size information, introducing a potential application for digital holography and image analysis in feed industry.

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

    Science.gov (United States)

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

    2006-12-01

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

  13. Two Size-Selective Mechanisms Specifically Trap Bacteria-Sized Food Particles in Caenorhabditis elegans

    OpenAIRE

    Fang-Yen, Christopher M.; Avery, Leon; Samuel, Aravinthan DT

    2009-01-01

    Caenorhabditis elegans is a filter feeder: it draws bacteria suspended in liquid into its pharynx, traps the bacteria, and ejects the liquid. How pharyngeal pumping simultaneously transports and filters food particles has been poorly understood. Here, we use high-speed video microscopy to define the detailed workings of pharyngeal mechanics. The buccal cavity and metastomal flaps regulate the flow of dense bacterial suspensions and exclude excessively large particles from entering the pharyn...

  14. A study of particle size distribution in zirconia-alumina powders

    International Nuclear Information System (INIS)

    Ramakrishnan, K.N.; Venkadesan, S.; Nagarajan, R.

    1996-01-01

    Powder particles, in general are characterized in terms of particle size, size distributions and composition for reasons associated with manufacturing problem based upon product quality, manufacturing convenience, cost and product handling convenience. Particle size analysis or the measurement of particle size distribution is a common effort in any physical, chemical or mechanical processes. This information and processing methods are intricate factors that relate to material behavior and/or physical properties of the fabricated product. The requirements for the formation of a product of particulate solids and its strength varies as the particle size and the size distribution changes. Also the transport properties and the chemical activity are related to the particle size and the size distribution. The choice of a distribution to represent a physical system is generally motivated by an understanding of the nature of underlying phenomenon and is verified by the available data. After a model has been chosen, its parameter must be determined. The reasonableness of a selected model on the basis of given data is especially important when the model is to be used for prediction. Two different approaches in this problem are probability plotting and statistical tests

  15. Towards High Capacity Li-ion Batteries Based on Silicon-Graphene Composite Anodes and Sub-micron V-doped LiFePO4 Cathodes

    Science.gov (United States)

    Loveridge, M. J.; Lain, M. J.; Johnson, I. D.; Roberts, A.; Beattie, S. D.; Dashwood, R.; Darr, J. A.; Bhagat, R.

    2016-01-01

    Lithium iron phosphate, LiFePO4 (LFP) has demonstrated promising performance as a cathode material in lithium ion batteries (LIBs), by overcoming the rate performance issues from limited electronic conductivity. Nano-sized vanadium-doped LFP (V-LFP) was synthesized using a continuous hydrothermal process using supercritical water as a reagent. The atomic % of dopant determined the particle shape. 5 at. % gave mixed plate and rod-like morphology, showing optimal electrochemical performance and good rate properties vs. Li. Specific capacities of >160 mAh g−1 were achieved. In order to increase the capacity of a full cell, V-LFP was cycled against an inexpensive micron-sized metallurgical grade Si-containing anode. This electrode was capable of reversible capacities of approximately 2000 mAh g−1 for over 150 cycles vs. Li, with improved performance resulting from the incorporation of few layer graphene (FLG) to enhance conductivity, tensile behaviour and thus, the composite stability. The cathode material synthesis and electrode formulation are scalable, inexpensive and are suitable for the fabrication of larger format cells suited to grid and transport applications. PMID:27898104

  16. Towards High Capacity Li-ion Batteries Based on Silicon-Graphene Composite Anodes and Sub-micron V-doped LiFePO4 Cathodes

    Science.gov (United States)

    Loveridge, M. J.; Lain, M. J.; Johnson, I. D.; Roberts, A.; Beattie, S. D.; Dashwood, R.; Darr, J. A.; Bhagat, R.

    2016-11-01

    Lithium iron phosphate, LiFePO4 (LFP) has demonstrated promising performance as a cathode material in lithium ion batteries (LIBs), by overcoming the rate performance issues from limited electronic conductivity. Nano-sized vanadium-doped LFP (V-LFP) was synthesized using a continuous hydrothermal process using supercritical water as a reagent. The atomic % of dopant determined the particle shape. 5 at. % gave mixed plate and rod-like morphology, showing optimal electrochemical performance and good rate properties vs. Li. Specific capacities of >160 mAh g-1 were achieved. In order to increase the capacity of a full cell, V-LFP was cycled against an inexpensive micron-sized metallurgical grade Si-containing anode. This electrode was capable of reversible capacities of approximately 2000 mAh g-1 for over 150 cycles vs. Li, with improved performance resulting from the incorporation of few layer graphene (FLG) to enhance conductivity, tensile behaviour and thus, the composite stability. The cathode material synthesis and electrode formulation are scalable, inexpensive and are suitable for the fabrication of larger format cells suited to grid and transport applications.

  17. Experimental study of the effect of wearing dust-proof mask on inhaled aerosol particle size

    International Nuclear Information System (INIS)

    Lu Shunguang; Mei Chongsheng; Wu Yuangqing; Ren Liuan.

    1985-01-01

    This paper describes a method for measuring particle size of inhaled aerosol with a phantom of human head wearing dust-proof mask and a cascade impactor. The results showed that AMAD of inhaled aerosol was degraded and the size distribution of particles changed when the dust-proof mask was wearing. The leak rate of mask increased as the size of dust particles decreased. The results are applicable to estimate internal exposure dose and to evaluate the dust-proof capacity of mask

  18. Rutile nanopowders for pigment production: Formation mechanism and particle size prediction

    Science.gov (United States)

    Zhang, Wu; Tang, Hongxin

    2018-01-01

    Formation mechanism and particle size prediction of rutile nanoparticles for pigment production were investigated. Anatase nanoparticles were observed by oriented attachment with parallel lattice fringe spaces of 0.2419 nm. Upon increasing the calcination temperature, the (1 1 0) plane of rutile was gradually observed, suggesting that the anatase (1 0 3) planes undergo internal structural rearrangement of oxygen and titanium ions into rutile phase due to ionic diffusion. Backpropagation neural network was used to predict particle size of rutile nanopowders, the prediction errors were all smaller than 2%, providing an efficient method to control particle size in pigment production.

  19. Phenomenological theory of size effects in ultrafine ferroelectric particles (PbTiO3-type)

    International Nuclear Information System (INIS)

    Jiang, B.; Bursill, L.A.

    1998-01-01

    A new phenomenological model is proposed and discussed to study the size effects on phase transitions in PbTiO 3 -type ferroelectric particles. This model, by taking size effects on the phenomenological Landau-Ginzburg-Devonshire coefficients into consideration, can successfully explain the size effects on Curie temperature, c/a ratio, thermal and dielectric properties of lead-titanate-type ferroelectric particles. Theoretical and experimental results for PbTiO 3 fine particles are also compared and discussed. The relationship between the current model and the model of Zhong et al (Phys. Rev. B 50, 698 (1994)) is also presented. (authors)

  20. Performance of japanese quails fed feeds containing different corn and limestone particle sizes

    OpenAIRE

    Berto,DA; Garcia,EA; Móri,C; Faitarone,ABG; Pelícia,K; Molino,AB

    2007-01-01

    This study aimed at evaluating performance and egg quality of Japanese quails fed feeds containing different corn and limestone particle sizes. A total number of 648 birds in the peak of production was distributed in a random complete block experimental design, using a 2x3 factorial arrangement (2 corn particle sizes and 3 limestone particle sizes). Birds were designated to one of two blocks, with six replicates of 18 birds each. Mean geometric diameter (MGD) values used were 0.617mm and 0.72...

  1. Particle size and surface charge affect particle uptake by human dendritic cells in an in vitro model

    DEFF Research Database (Denmark)

    Foged, Camilla; Brodin, Birger; Frøkjær, Sven

    2005-01-01

    Current vaccine development includes optimization of antigen delivery to antigen presenting cells, such as dendritic cells (DC). Particulate systems have attracted increasing attention in the development of vaccine delivery systems. In the present study, we investigated DC uptake of model...... fluorescent polystyrene particles with a broad size range and variable surface properties. Localization of particles was investigated using confocal laser scanning microscopy and uptake was quantified by flow cytometry. Immature DC were generated from mononuclear cells isolated from human blood...

  2. Toward selective electrochemical 'E-tongue': Potentiometric DO sensor based on sub-micron ZnO-RuO{sub 2} sensing electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zhuiykov, Serge, E-mail: serge.zhuiykov@csiro.au [CSIRO, Materials Science and Engineering Division, 37 Graham Road, Highett, VIC 3190 (Australia); Kats, Eugene [CSIRO, Materials Science and Engineering Division, 37 Graham Road, Highett, VIC 3190 (Australia); Plashnitsa, Vladimir [Research and Education Centre of Carbon Resources, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan); Miura, Norio [KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2011-06-01

    Highlights: > We examine ZnO-doped RuO{sub 2} sensing electrode of DO sensor. > Study of ZnO-RuO{sub 2} confirmed the development of high surface-to-volume ratio. > Developed sensing electrode is insensitive to the presence of various dissolved salts. > 20 mol% ZnO-doped RuO{sub 2} sensing electrode enables maximum DO sensitivity. > We conclude that DO sensor based on ZnO-RuO{sub 2} electrode can work at 11-30 deg. C. - Abstract: Planar dissolved oxygen (DO) sensors based on thick-film ZnO-RuO{sub 2} sensing electrodes (SEs) with different mol% of ZnO were prepared on the alumina substrates using a screen-printing method and their structural and electrochemical properties were closely studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), electrochemical impedance spectroscopy (EIS) and energy-dispersive spectroscopy (EDS) techniques. Structural and electrochemical properties of ZnO-RuO{sub 2}-SEs have been investigated. Interference testing ascertained that the DO sensor based on sub-micron ZnO-RuO{sub 2}-SE is insensitive to the presence of various dissolved ions including Cl{sup -}, Li{sup +}, SO{sub 4}{sup 2-}, NO{sup 3-}, Ca{sup 2+}, PO{sub 4}{sup 3-}, Mg{sup 2+}, Na{sup +} and K{sup +} within a concentration range of 10{sup -7} to 10{sup -1} mol/L for DO measurement from 0.5 to 8.0 ppm in the test solution at a temperature range of 11-30 deg. C. These dissolved salts had practically no effect on the sensor's output potential difference response, whereas Br{sup -} ions had some effects at concentration more than 10{sup -3} mol/L. The relationship between DO and the sensor's potential difference was found to be relatively linear with the maximum sensitivity of -50.6 mV per decade was achieved at 20 mol% ZnO at 7.35 pH. The response and recovery time to pH changes for the planar device based on 20 mol% ZnO-RuO{sub 2}-SE was found to be 10 and 25 s

  3. [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.

  4. Particle Size Distributions in Chondritic Meteorites: Evidence for Pre-Planetesimal Histories

    Science.gov (United States)

    Simon, J. I.; Cuzzi, J. N.; McCain, K. A.; Cato, M. J.; Christoffersen, P. A.; Fisher, K. R.; Srinivasan, P.; Tait, A. W.; Olson, D. M.; Scargle, J. D.

    2018-01-01

    Magnesium-rich silicate chondrules and calcium-, aluminum-rich refractory inclusions (CAIs) are fundamental components of primitive chondritic meteorites. It has been suggested that concentration of these early-formed particles by nebular sorting processes may lead to accretion of planetesimals, the planetary bodies that represent the building blocks of the terrestrial planets. In this case, the size distributions of the particles may constrain the accretion process. Here we present new particle size distribution data for Northwest Africa 5717, a primitive ordinary chondrite (ungrouped 3.05) and the well-known carbonaceous chondrite Allende (CV3). Instead of the relatively narrow size distributions obtained in previous studies (Ebel et al., 2016; Friedrich et al., 2015; Paque and Cuzzi, 1997, and references therein), we observed broad size distributions for all particle types in both meteorites. Detailed microscopic image analysis of Allende shows differences in the size distributions of chondrule subtypes, but collectively these subpopulations comprise a composite "chondrule" size distribution that is similar to the broad size distribution found for CAIs. Also, we find accretionary 'dust' rims on only a subset (approximately 15-20 percent) of the chondrules contained in Allende, which indicates that subpopulations of chondrules experienced distinct histories prior to planetary accretion. For the rimmed subset, we find positive correlation between rim thickness and chondrule size. The remarkable similarity between the size distributions of various subgroups of particles, both with and without fine grained rims, implies a common size sorting process. Chondrite classification schemes, astrophysical disk models that predict a narrow chondrule size population and/or a common localized formation event, and conventional particle analysis methods must all be critically reevaluated. We support the idea that distinct "lithologies" in NWA 5717 are nebular aggregates of

  5. 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.

  6. Systems and methods of varying charged particle beam spot size

    Science.gov (United States)

    Chen, Yu-Jiuan

    2014-09-02

    Methods and devices enable shaping of a charged particle beam. A modified dielectric wall accelerator includes a high gradient lens section and a main section. The high gradient lens section can be dynamically adjusted to establish the desired electric fields to minimize undesirable transverse defocusing fields at the entrance to the dielectric wall accelerator. Once a baseline setting with desirable output beam characteristic is established, the output beam can be dynamically modified to vary the output beam characteristics. The output beam can be modified by slightly adjusting the electric fields established across different sections of the modified dielectric wall accelerator. Additional control over the shape of the output beam can be excreted by introducing intentional timing de-synchronization offsets and producing an injected beam that is not fully matched to the entrance of the modified dielectric accelerator.

  7. 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

    1997-12-31

    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.

  8. 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.

  9. Effect of particle size distribution on permeability in the randomly packed porous media

    Science.gov (United States)

    Markicevic, Bojan

    2017-11-01

    An answer of how porous medium heterogeneity influences the medium permeability is still inconclusive, where both increase and decrease in the permeability value are reported. A numerical procedure is used to generate a randomly packed porous material consisting of spherical particles. Six different particle size distributions are used including mono-, bi- and three-disperse particles, as well as uniform, normal and log-normal particle size distribution with the maximum to minimum particle size ratio ranging from three to eight for different distributions. In all six cases, the average particle size is kept the same. For all media generated, the stochastic homogeneity is checked from distribution of three coordinates of particle centers, where uniform distribution of x-, y- and z- positions is found. The medium surface area remains essentially constant except for bi-modal distribution in which medium area decreases, while no changes in the porosity are observed (around 0.36). The fluid flow is solved in such domain, and after checking for the pressure axial linearity, the permeability is calculated from the Darcy law. The permeability comparison reveals that the permeability of the mono-disperse medium is smallest, and the permeability of all poly-disperse samples is less than ten percent higher. For bi-modal particles, the permeability is for a quarter higher compared to the other media which can be explained by volumetric contribution of larger particles and larger passages for fluid flow to take place.

  10. Role of particle size and composition in metal adsorption by solids deposited on urban road surfaces

    International Nuclear Information System (INIS)

    Gunawardana, Chandima; Egodawatta, Prasanna; Goonetilleke, Ashantha

    2014-01-01

    Despite common knowledge that the metal content adsorbed by fine particles is relatively higher compared to coarser particles, the reasons for this phenomenon have gained little research attention. The research study discussed in the paper investigated the variations in metal content for different particle sizes of solids associated with pollutant build-up on urban road surfaces. Data analysis confirmed that parameters favourable for metal adsorption to solids such as specific surface area, organic carbon content, effective cation exchange capacity and clay forming minerals content decrease with the increase in particle size. Furthermore, the mineralogical composition of solids was found to be the governing factor influencing the specific surface area and effective cation exchange capacity. There is high quartz content in particles >150 μm compared to particles <150 μm. As particle size reduces below 150 μm, the clay forming minerals content increases, providing favourable physical and chemical properties that influence adsorption. -- Highlights: • Physico-chemical parameters investigated in build-up samples from 32 road surfaces. • Mineralogical composition primarily governs the physico-chemical characteristics. • High clay forming mineral content in fine solids increases SSA and ECEC. • Characteristics influenced by quartz and amorphous content with particle size. • High quartz content in coarse particles contributes reduced metal adsorption. -- The mineralogical composition of solids is the governing factor influencing metal adsorption to solids in pollutant build-up on urban surfaces

  11. Fundamental study on laser manipulation of contamination particles with determining shape, size and species

    International Nuclear Information System (INIS)

    Shimizu, Isao; Fujii, Taketsugu

    1995-01-01

    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)

  12. Evaluating unsupervised methods to size and classify suspended particles using digital in-line holography

    Science.gov (United States)

    Davies, Emlyn J.; Buscombe, Daniel D.; Graham, George W.; Nimmo-Smith, W. Alex M.

    2015-01-01

    Substantial information can be gained from digital in-line holography of marine particles, eliminating depth-of-field and focusing errors associated with standard lens-based imaging methods. However, for the technique to reach its full potential in oceanographic research, fully unsupervised (automated) methods are required for focusing, segmentation, sizing and classification of particles. These computational challenges are the subject of this paper, in which we draw upon data collected using a variety of holographic systems developed at Plymouth University, UK, from a significant range of particle types, sizes and shapes. A new method for noise reduction in reconstructed planes is found to be successful in aiding particle segmentation and sizing. The performance of an automated routine for deriving particle characteristics (and subsequent size distributions) is evaluated against equivalent size metrics obtained by a trained operative measuring grain axes on screen. The unsupervised method is found to be reliable, despite some errors resulting from over-segmentation of particles. A simple unsupervised particle classification system is developed, and is capable of successfully differentiating sand grains, bubbles and diatoms from within the surf-zone. Avoiding miscounting bubbles and biological particles as sand grains enables more accurate estimates of sand concentrations, and is especially important in deployments of particle monitoring instrumentation in aerated water. Perhaps the greatest potential for further development in the computational aspects of particle holography is in the area of unsupervised particle classification. The simple method proposed here provides a foundation upon which further development could lead to reliable identification of more complex particle populations, such as those containing phytoplankton, zooplankton, flocculated cohesive sediments and oil droplets.

  13. Relation between particle size and properties of some bituminous coals

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, A.D.; Cheng, M.; Goulet, J.-C.; Furimsky, E. (CANMET, Ottawa, ON (Canada). Energy Research Laboratories)

    1990-02-01

    Coal fractions of different size distributions exhibited different H/C ratio, ash and sulphur contents, and surface structures. This was confirmed using two low-sulphur and two high-sulphur bituminous coals. The effect was much less pronounced for low-sulphur coals than for high-sulphur coals. A significant difference in properties was noted between the two high-sulphur coals in spite of similar basic compositional parameters. This was confirmed by the fractal dimensionality factor D of Illinois No. 6 coal, which exceeded the theoretical value. 14 refs., 9 figs., 5 tabs.

  14. Effects of the finite particle size in turbulent wall-bounded flows of dense suspensions

    Science.gov (United States)

    Costa, Pedro; Picano, Francesco; Brandt, Luca; Breugem, Wim-Paul

    2018-05-01

    We use interface-resolved simulations to study finite-size effects in turbulent channel flow of neutrally-buoyant spheres. Two cases with particle sizes differing by a factor of 2, at the same solid volume fraction of 20% and bulk Reynolds number are considered. These are complemented with two reference single-phase flows: the unladen case, and the flow of a Newtonian fluid with the effective suspension viscosity of the same mixture in the laminar regime. As recently highlighted in Costa et al. (PRL 117, 134501), a particle-wall layer is responsible for deviations of the statistics from what is observed in the continuum limit where the suspension is modeled as a Newtonian fluid with an effective viscosity. Here we investigate the fluid and particle dynamics in this layer and in the bulk. In the particle-wall layer, the near wall inhomogeneity has an influence on the suspension micro-structure over a distance proportional to the particle size. In this layer, particles have a significant (apparent) slip velocity that is reflected in the distribution of wall shear stresses. This is characterized by extreme events (both much higher and much lower than the mean). Based on these observations we provide a scaling for the particle-to-fluid apparent slip velocity as a function of the flow parameters. We also extend the flow scaling laws in to second-order Eulerian statistics in the homogeneous suspension region away from the wall. Finite-size effects in the bulk of the channel become important for larger particles, while negligible for lower-order statistics and smaller particles. Finally, we study the particle dynamics along the wall-normal direction. Our results suggest that 1-point dispersion is dominated by particle-turbulence (and not particle-particle) interactions, while differences in 2-point dispersion and collisional dynamics are consistent with a picture of shear-driven interactions.

  15. Emanation of 232U and its radioactive daughter products from respirable size particles

    International Nuclear Information System (INIS)

    Cuddihy, R.G.; Griffith, W.C.; Hoover, M.D.; Kanapilly, G.M.; Stalnaker, N.D.

    1978-01-01

    This study is to develop a model for the emanation of 232 U and its radioactive daughter products from particles of Th-U fuel material. The radiation doses to internal organs following inhalation of these particles can only be calculated by knowing the rate of emanation of the daughters from particles in the lung and the subsequent excretion or translocation of the daughters to other organs. The emanation mechanisms are recoil of the daughter nuclei from the particle during alpha decay of the parent, diffusion of inert gas daughters from the particle and dissolution of the particle itself in biological fluids. Experiments to evaluate these mechanisms will involve ThO 2 and UO 2 particles in the size range 0.1 to 1.0 μm MMAD uniformly labeled with 232 U. The influence of the material temperature history on emanation will be investigated by heat treating particles at 600 and 1400 0 C

  16. The influence of powder particle size on properties of Cu-Al2O3 composites

    Directory of Open Access Journals (Sweden)

    Rajković V.

    2009-01-01

    Full Text Available Inert gas atomized prealloyed copper powder containing 2 wt.% Al (average particle size ≈ 30 μm and a mixture consisting of copper (average particle sizes ≈ 15 μm and 30 μm and 4 wt.% of commercial Al2O3 powder particles (average particle size ≈ 0.75 μm were milled separately in a high-energy planetary ball mill up to 20 h in air. Milling was performed in order to strengthen the copper matrix by grain size refinement and Al2O3 particles. Milling in air of prealloyed copper powder promoted formation of finely dispersed nano-sized Al2O3 particles by internal oxidation. On the other side, composite powders with commercial micro-sized Al2O3 particles were obtained by mechanical alloying. Following milling, powders were treated in hydrogen at 400 0C for 1h in order to eliminate copper oxides formed on their surface during milling. Hot-pressing (800 0C for 3 h in argon at pressure of 35 MPa was used for compaction of milled powders. Hot-pressed composite compacts processed from 5 and 20 h milled powders were additionally subjected to high temperature exposure (800°C for 1 and 5h in argon in order to examine their thermal stability. The results were discussed in terms of the effects of different size of starting powders, the grain size refinement and different size of Al2O3 particles on strengthening, thermal stability and electrical conductivity of copper-based composites.

  17. Measurements of humidified particle number size distributions in a Finnish boreal forest: derivation of hygroscopic particle growth factors

    Energy Technology Data Exchange (ETDEWEB)

    Birmili, W.; Schwirn, K.; Nowak, A.; Rose, D.; Wiedensohler, A. (Leibniz Institute for Tropospheric Research, Leipzig (Germany)); Petaejae, T.; Haemeri, K.; Aalto, P.; Kulmala, M.; Boy, M. (Dept. of Physics, Univ. of Helsinki (Finland)); Joutsensaari, J. (Univ. of Kuopio, Dept. of Physics (Finland))

    2009-07-01

    Dry and humidified size distributions of atmospheric particles were characterised at the atmospheric research station SMEAR 2, Finland between May and July 2004. Particles were classified in a size range between 3 and 800 nm at controlled relative humidities up to 90% by two instruments complementary in size range (HDMPS; Nano-HDMPS). Using the summation method, descriptive hygroscopic growth factors (DHGF) were derived for particle diameters between 70 and 300 nm by comparing dry and humidified size distributions. At 90% relative humidity, DHGF showed mean values between 1.25 and 1.45 in the accumulation mode, between 1.20 and 1.25 in the Aitken mode, and between 1.15 and 1.20 in the nucleation mode. Due to the high size resolution of the method, the transition in DHGF between the Aitken and accumulation modes, which reflects differences in the soluble fraction, could be pinpointed efficiently. For the accumulation mode, experimental DHGFs were compared to those calculated from a simplistic growth model initialised by in-situ chemical composition measurements, and yielded maximum deviations around 0.1. The variation in DHGF could only imperfectly be linked to meteorological factors. A pragmatic parameterisation of DHGF as a function of particle diameter and relative humidity was derived, and subsequently used to study the sensitivity of the condensational sink parameter (CS) as a function of height in a well-mixed boundary layer. (orig.)

  18. The particle size characteristics of fluvial suspended sediment in the Humber and Tweed catchments, UK

    Science.gov (United States)

    Walling; Owens; Waterfall; Leeks; Wass

    2000-05-05

    This paper presents information on the absolute (chemically-dispersed) particle size characteristics of the suspended sediment transported by rivers in the Humber and Tweed basins during the period 1994-1998. For most of the rivers, > 95% of the suspended sediment load at the time of sampling was 63 microm (i.e. sand-sized material). The sediment transported in the two basins were similar. There were, however, noticeable spatial variations in the particle size composition of suspended sediment within the study basins, which reflected the particle size of the sediment sources and their spatial variation, and the selectivity of the sediment mobilization and delivery processes. When particle size parameters were plotted against discharge, there were no significant relationships, although there was some evidence of trends varying between sites. The lack of significant relationships with discharge reflects the fact that sediment particle size is largely supply-controlled, rather than a function of flow and hydraulics. When particle size variations were examined during individual storm events, there was evidence of a pulse of coarse sediment on the rising limb of the hydrograph. This may reflect the remobilization of coarse channel bed sediment as flow velocity and shear stress increase. Finer sediment was transported subsequently during the hydrograph peak and on the falling limb. The findings reported have important implications for understanding and modelling suspended sediment, and associated contaminant, dynamics in river basins.

  19. Study of effect of variables on particle size of telmisartan nanosuspensions using box-Behnken design.

    Science.gov (United States)

    Rao, M R P; Bajaj, A

    2014-12-01

    Telmisartan, an orally active nonpeptide angiotensin II receptor antagonist is a BCS Class II drug having aqueous solubility of 9.9 µg/ml and hence oral bioavailability of 40%. The present study involved preparation of nanosuspensions by evaporative antisolvent precipitation technique to improve the saturation solubility and dissolution rate of telmisartan. Various stabilizers such as TPGS, PVPK 30, PEG 6000 were investigated of which TPGS was found to provide maximum decrease in particle size and accord greater stability to the nanosuspensions. Box-Behnken design was used to investigate the effect of independent variables like stabilizer concentration, time and speed of stirring on particle size of nanosuspensions. Pharmacodynamic studies using Goldblatt technique were undertaken to evaluate the effect of nano-sizing on the hypotensive effect of the drug. Concentration of TPGS and speed of rotation were found to play an important role in particle size of the nanosuspensions whereas time of stirring displayed an exponential relationship with particle size. Freeze dried nanocrystals obtained from nanosuspension of least particle size were found to have increased saturation solubility of telmisartan in different dissolution media. The reconstituted nanosuspension was found to reduce both systolic and diastolic blood pressure without affecting pulse pressure and heart rate. Statistical tools can be used to identify key process and formulation parameters which play a significant role in controlling the particle size in nanosuspensions. © Georg Thieme Verlag KG Stuttgart · New York.

  20. SIZE DISTRIBUTIONS OF SOLAR FLARES AND SOLAR ENERGETIC PARTICLE EVENTS

    International Nuclear Information System (INIS)

    Cliver, E. W.; Ling, A. G.; Belov, A.; Yashiro, S.

    2012-01-01

    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.

  1. Control over particle size distribution by autoclaving poloxamer-stabilized trimyristin nanodispersions

    DEFF Research Database (Denmark)

    Göke, Katrin; Roese, Elin; Arnold, Andreas

    2016-01-01

    Lipid nanoparticles are under investigation as delivery systems for poorly water-soluble drugs. The particle size in these dispersions strongly influences important pharmaceutical properties like biodistribution and drug loading capacity; it should be below 500 nm for direct injection into the bl......Lipid nanoparticles are under investigation as delivery systems for poorly water-soluble drugs. The particle size in these dispersions strongly influences important pharmaceutical properties like biodistribution and drug loading capacity; it should be below 500 nm for direct injection...... treatment thus seems to be a promising approach to achieve the desired narrow particle size distribution of such dispersions. Related to the lipid content, suspension particles needed more emulsifier for stabilization than emulsion droplets, and smaller particles more than larger ones....

  2. Effect of milling time on the structure, particle size, and morphology of montmorillonite

    International Nuclear Information System (INIS)

    Abareshi, M.

    2017-01-01

    In the current research, effect of milling on the structure, particle size and morphology of montmorillonite was investigated. For this purpose, the montmorillonite was analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Then the montmorillonite was milled using high energy planetary ball mill at different milling times (1-60 hours). After that, the structure, particle size and morphology of all samples were investigated by XRD, FTIR, SEM, and transmission electron microscopy. Results showed that the ball milling causes the particle size reduction of clay and separation of the clay layers. Moreover, ball milling increases the overall structural disorder and transforms the crystalline structure into an amorphous phase. Also, the morphology of clay particle changes from layered to aggregates of almost rounded particles after 60 hours of milling.

  3. Electromechanical characterization of individual micron-sized metal coated polymer particles

    Energy Technology Data Exchange (ETDEWEB)

    Bazilchuk, Molly; Kristiansen, Helge [Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim 7491 (Norway); Conpart AS, Skjetten 2013 (Norway); Pettersen, Sigurd Rolland; Zhang, Zhiliang; He, Jianying, E-mail: jianying.he@ntnu.no [Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim 7491 (Norway)

    2016-06-28

    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.

  4. Electromechanical characterization of individual micron-sized metal coated polymer particles

    International Nuclear Information System (INIS)

    Bazilchuk, Molly; Kristiansen, Helge; Pettersen, Sigurd Rolland; Zhang, Zhiliang; He, Jianying

    2016-01-01

    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.

  5. Measurement of particle size distribution and mass concentration of nuclear fuel aerosols

    International Nuclear Information System (INIS)

    Pickering, S.

    1982-01-01

    The particle size distribution and particle mass concentration of a nuclear fuel aerosol is measured by admitting the aerosol into a vertically-extending container, positioning an alpha particle detector within the container so that its window is horizontal and directed vertically, stopping the admission of aerosol into the container, detecting the alpha-activity of the particles of the aerosol sedimenting onto the detector window (for example in a series of equal time intervals until a constant level is reached), and converting the alpha-activity measurements into particle size distribution and/or particle mass concentration measurements. The detector is attached to a pivotted arm and by raising a counterweight can be lowered from the container for cleaning. (author)

  6. The effect of particles in different sizes on the mechanical properties of spray formed steel composites

    DEFF Research Database (Denmark)

    Petersen, Kenneth; Pedersen, A. S.; Pryds, N.

    2000-01-01

    particle size of 46 and 134 μm were carried out with respect to their mechanical properties e.g. wear resistance and tensile strength. It was found that the addition of Al2O3 particles to the steel improves its wear properties and reduces the elongation and tensile strength of the material......The main objective of the work was to investigate the effect of addition of ceramic particles with different size distributions on the mechanical properties, e.g. wear resistance and tensile strength, of spray formed materials. The experiments were carried out in a spray-forming unit at Risø...... National Laboratory, Denmark, where composites with a low alloyed boron steel (0.2 wt.% carbon) matrix containing alumina particles were produced. A comparison between cast hot-rolled material without particles, spray formed material without particles and the spray formed composites with an average ceramic...

  7. A simple algorithm for measuring particle size distributions on an uneven background from TEM images

    DEFF Research Database (Denmark)

    Gontard, Lionel Cervera; Ozkaya, Dogan; Dunin-Borkowski, Rafal E.

    2011-01-01

    Nanoparticles have a wide range of applications in science and technology. Their sizes are often measured using transmission electron microscopy (TEM) or X-ray diffraction. Here, we describe a simple computer algorithm for measuring particle size distributions from TEM images in the presence of a...... application to images of heterogeneous catalysts is presented.......Nanoparticles have a wide range of applications in science and technology. Their sizes are often measured using transmission electron microscopy (TEM) or X-ray diffraction. Here, we describe a simple computer algorithm for measuring particle size distributions from TEM images in the presence...

  8. The effect of reducing alfalfa haylage particle size on cows in early lactation.

    Science.gov (United States)

    Kononoff, P J; Heinrichs, A J

    2003-04-01

    The objective of this experiment was to evaluate effects of reducing forage particle size on cows in early lactation based on measurements of the Penn State Particle Separator (PSPS). Eight cannulated, multiparous cows averaging 19 +/- 4 d in milk and 642 +/- 45 kg BW were assigned to one of two 4 x 4 Latin Squares. During each of the 23-d periods, animals were offered one of four diets, which were chemically identical but included alfalfa haylage of different particle size; short (SH), mostly short (MSH), mostly long (MLG), and long (LG). Physically effective neutral detergent fiber (peNDF) was determined by measuring the amount of neutral detergent fiber retained on a 1.18 mm screen and was similar across diets (25.7, 26.2, 26.4, 26.7%) but the amount of particles >19.0 mm significantly decreased with decreasing particle size. Reducing haylage particle size increased dry matter intake linearly (23.3, 22.0, 20.9, 20.8 kg for SH, MSH, MLG, LG, respectively). Milk production and percentage fat did not differ across treatments averaging 35.5 +/- 0.68 kg milk and 3.32 +/- 0.67% fat, while a quadratic effect was observed for percent milk protein, with lowest values being observed for LG. A quadratic effect was observed for mean rumen pH (6.04, 6.15, 6.13, 6.09), while A:P ratio decreased linearly (2.75, 2.86, 2.88, 2.92) with decreasing particle size. Total time ruminating increased quadratically (467, 498, 486, 468 min/d), while time eating decreased linearly (262, 253, 298, 287 min/d) with decreasing particle size. Both eating and ruminating per unit of neutral detergent fiber intake decreased with reducing particle size (35.8, 36.7, 44.9, 45.6 min/kg; 19.9, 23.6, 23.5, 23.5 min/kg). Although chewing activity was closely related to forage particle size, effects on rumen pH were small, indicating factors other than particle size are critical in regulating pH when ration neutral detergent fiber met recommended levels. Feeding alfalfa haylage based rations of reduced

  9. Study of Acid Hydrolysis on Organic Waste: Understanding The Effect of Delignification and Particle Size

    Directory of Open Access Journals (Sweden)

    Anwar Nadiem

    2018-01-01

    Full Text Available Organic wastes from Swiettenia marcophylla L, Artocarpus heterophyllus L, Mangifera indica L, and Annona muricata L were prepared by grinding into 0.1875, 0.3750, 0.7500 mm of particle size and delignified by 2% NaOH at 80°C for 90 minutes. Acid dilution hydrolysis process with H2SO4 1% was performed at 150°C for 120 minutes in a closed reactor. The effect of particle size and delignification on and reducing sugar concentration were investigated. The result showed (1 leaves that can be used as raw material to produce hydrogen should have 38–49% cellulose and hemicellulose. (2 Reducing sugar concentration increased with particle size reduction and delignification. (3 the best result with the highest reducing sugar concentration was achieved by 0.1875 mm particle size with delignification on Annona muricata L.

  10. Effects of Na and Ca on particle size; Effect of filtering on UV absorbance

    Data.gov (United States)

    U.S. Environmental Protection Agency — Effects of Na and Ca on particle size; Effect of filtering on UV absorbance. This dataset is associated with the following publication: Bouchard, D., C. Knightes, X....

  11. Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method.

    Science.gov (United States)

    Kalani, Mahshid; Yunus, Robiah

    2012-01-01

    The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks.

  12. Effect of particle size of granules on some mechanical properties of ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... compacts formed from larger granules as a result of plastic deformation and fragmentation than ... whether an increase or a decrease in particle size will ... many) was used for the preparation of the tablets from the various.

  13. Specific activity of uranium and thorium in marketable rock phosphate as a function of particle size

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, R; McKlveen, J W [Arizona State Univ., Tempe (USA); Jenkins, R [Phillip Morris Research Center, Richmond, VA (USA); McDowell, W J [Oak Ridge National Lab., TN (USA)

    1980-07-01

    Marketable rock phosphate fertilizer from Florida was classified into seven particle size fractions ranging from 149 ..mu..m to less than 0.5 ..mu..m using a Bahco Microparticle Classifier and air elutriation. The resulting size fractions were assayed for U and /sup 230/Th by solvent extraction and liquid scintillation ..cap alpha..-spectroscopy. Results indicated that the specific activity of U and /sup 230/Th increased with decreasing particle size. Maximum activities of 110 pCi/g U and 50 pCi/g /sup 230/Th were found in particles less than 1.0 ..mu..m in aerodynamic diameter. Qualitative emission spectrographic analysis of the fractions revealed that the concentrations of Al, Cu, Mg, Na, Ti and Zn also increased with decreasing particle size.

  14. Effect of particle size on colloidal zirconia rheology at the isoelectric point

    International Nuclear Information System (INIS)

    Leong, Y.K.; Scales, P.J.; Healy, T.W.; Boger, D.V.

    1995-01-01

    This paper examines the effects of particle concentration and size on the yield stress of ZrO 2 suspensions at a well-defined surface chemistry condition of the isoelectric point (IEP). At the IEP, the relationship between yield stress τ y max and particulate volume fraction φ s , and mean particle size d was evaluated to be τ y max = K φ s 4.0 /d 2.0 . The difference in size distribution of the various ZrO 2 suspensions examined causes some degree of scatter in the data used to establish the τ y max , φ s , and d relation. The use of particle concentration n t based on the fine size fraction instead of volume fraction φ s provided a better correlation, because the fine particles govern the properties of the flocculated network structure

  15. Development of an ejecta particle size measurement diagnostic based on Mie scattering

    Energy Technology Data Exchange (ETDEWEB)

    Schauer, Martin Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Buttler, William Tillman [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Frayer, Daniel K. [National Security Tech, Inc., Los Alamos, NM (United States); Grover, Michael [National Security Technologies, Santa Barbara, CA (United States). Special Technologies Lab.; Monfared, Shabnam Kalighi [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stevens, Gerald D. [National Security Technologies, Santa Barbara, CA (United States). Special Technologies Lab.; Stone, Benjamin J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Turley, William Dale [National Security Technologies, Santa Barbara, CA (United States). Special Technologies Lab.

    2017-09-27

    The goal of this work is to determine the feasibility of extracting the size of particles ejected from shocked metal surfaces (ejecta) from the angular distribution of light scattered by a cloud of such particles. The basis of the technique is the Mie theory of scattering, and implicit in this approach are the assumptions that the scattering particles are spherical and that single scattering conditions prevail. The meaning of this latter assumption, as far as experimental conditions are concerned, will become clear later. The solution to Maxwell’s equations for spherical particles illuminated by a plane electromagnetic wave was derived by Gustav Mie more than 100 years ago, but several modern treatises discuss this solution in great detail. The solution is a complicated series expansion of the scattered electric field, as well as the field within the particle, from which the total scattering and absorption cross sections as well as the angular distribution of scattered intensity can be calculated numerically. The detailed nature of the scattering is determined by the complex index of refraction of the particle material as well as the particle size parameter, x, which is the product of the wavenumber of the incident light and the particle radius, i.e. x = 2rπ= λ. Figure 1 shows the angular distribution of scattered light for different particle size parameters and two orthogonal incident light polarizations as calculated using the Mie solution. It is obvious that the scattering pattern is strongly dependent on the particle size parameter, becoming more forward-directed and less polarizationdependent as the particle size parameter increases. This trend forms the basis for the diagnostic design.

  16. Effect of particle size on laser-induced breakdown spectroscopy analysis of alumina suspension in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Rosado, Jose Carlos [CEA, DEN, SEARS, LANIE, 91191 Gif-sur-Yvette (France); Univ. Paris Sud, Faculty of Pharmaceutical Sciences, Public Health and Environment UMR 8079, 5 rue J.B. Clement, 92296 Chatenay-Malabry (France); National University of Engineering, Faculty of Science, P.O. Box 31-139, Av. Tupac Amaru 210, Lima (Peru); L' hermite, Daniel, E-mail: daniel.lhermite@cea.fr [CEA, DEN, SEARS, LANIE, 91191 Gif-sur-Yvette (France); Levi, Yves [Univ. Paris Sud, Faculty of Pharmaceutical Sciences, Public Health and Environment UMR 8079, 5 rue J.B. Clement, 92296 Chatenay-Malabry (France)

    2012-08-15

    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 {mu}m to 90 {mu}m) of Al{sub 2}O{sub 3} 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 {mu}m as ablated water column depth. - Highlights: Black-Right-Pointing-Pointer We have identified a decrease of calibration curve when particle size increases. Black-Right-Pointing-Pointer Partial particle ablation has been identified as the origin of this effect. Black-Right-Pointing-Pointer The ablation rate on Al{sub 2}O{sub 3} particles in suspension in water has been estimated. Black-Right-Pointing-Pointer We can determine the deepness of the interaction volume into the liquid.

  17. Size effects in PbTiO3 nanocrystals: Effect of particle size on spontaneous polarization and strains

    Science.gov (United States)

    Akdogan, E. K.; Rawn, C. J.; Porter, W. D.; Payzant, E. A.; Safari, A.

    2005-04-01

    The spontaneous polarization (Ps) and spontaneous strains (xi) in mechanically unclamped and surface charge compensated PbTiO3 nanocrystals were determined as a function of particle size in the range <150nm by differential scanning calorimetry and x-ray powder diffraction, respectively. Significant deviations from bulk order parameters (P,xi) have been observed as the particle size decreased below ˜100nm. The critical size (rc) below which the ferroelectric tetragonal phase transforms to the paraelectric cubic phase was determined as ˜15nm. The depression in transition temperature with particle size is 14 °C at 28 nm. No change in the order of m3m →4mm ferrodistortive phase transition is observed. A simple analysis showed that ΔHtr/(kBT )˜103 at 25 °C for r =16nm, indicating that the stabilization of the cubic phase at rc cannot be linked to an instability in dipolar ordering due to thermal agitations. Comparison of the spontaneous volumetric strains with the strain induced by surface stress indicated that the effect of surface stress on ferroelectric phase stability was negligible. Anomalies in electrostrictive properties were determined for r →rc. The observed size dependence of PS is attributed to the reduced extent of long-range dipole-dipole interactions that arise due to the changes in bonding characteristics of ions with decreasing particle size in the perovskite lattice, in conformity with a recent study by Tsunekawa et al. [Phys. Rev. Lett. 85 (16), 4340 (2000)].

  18. Size-resolved chemical composition, effective density, and optical properties of biomass burning particles

    Science.gov (United States)

    Zhai, Jinghao; Lu, Xiaohui; Li, Ling; Zhang, Qi; Zhang, Ci; Chen, Hong; Yang, Xin; Chen, Jianmin

    2017-06-01

    Biomass burning aerosol has an important impact on the global radiative budget. A better understanding of the correlations between the mixing states of biomass burning particles and their optical properties is the goal of a number of current studies. In this work, the effective density, chemical composition, and optical properties of rice straw burning particles in the size range of 50-400 nm were measured using a suite of online methods. We found that the major components of particles produced by burning rice straw included black carbon (BC), organic carbon (OC), and potassium salts, but the mixing states of particles were strongly size dependent. Particles of 50 nm had the smallest effective density (1.16 g cm-3) due to a relatively large proportion of aggregate BC. The average effective densities of 100-400 nm particles ranged from 1.35 to 1.51 g cm-3 with OC and inorganic salts as dominant components. Both density distribution and single-particle mass spectrometry showed more complex mixing states in larger particles. Upon heating, the separation of the effective density distribution modes confirmed the external mixing state of less-volatile BC or soot and potassium salts. The size-resolved optical properties of biomass burning particles were investigated at two wavelengths (λ = 450 and 530 nm). The single-scattering albedo (SSA) showed the lowest value for 50 nm particles (0.741 ± 0.007 and 0.889 ± 0.006) because of the larger proportion of BC content. Brown carbon played an important role for the SSA of 100-400 nm particles. The Ångström absorption exponent (AAE) values for all particles were above 1.6, indicating the significant presence of brown carbon in all sizes. Concurrent measurements in our work provide a basis for discussing the physicochemical properties of biomass burning aerosol and its effects on the global climate and atmospheric environment.

  19. Effect of corn silage particle size and level of soybean oil on ruminal ...

    African Journals Online (AJOL)

    To determine the effects of two corn silage particle size (coarse particle with geometric mean of 5.83 ± 2.47 mm and fine particle with geometric mean of 4.74 ± 2.74 mm) and two levels of soybean oil (0 and 4% of DM) on ruminal mat composition, distribution and consistency, four two years fistulated ruminant Zel ewes (BW ...

  20. Surface particle sizes on armoured gravel streambeds: Effects of supply and hydraulics

    Science.gov (United States)

    Peter J. Whiting; John G. King

    2003-01-01

    Most gravel-bed streams exhibit a surface armour in which the median grain size of the surface particles is coarser than that of the subsurface particles. This armour has been interpreted to result when the supply of sediment is less than the ability of the stream to move sediment. While there may be certain sizes in the bed for which the supply is less than the...

  1. Stable solutions of a scalar conservation law for particle-size segregation in dense granular avalanches

    OpenAIRE

    Shearer, M.; Gray, J. M N T; Thornton, A. R.

    2008-01-01

    Dense, dry granular avalanches are very efficient at sorting the larger particles towards the free surface of the flow, and finer grains towards the base, through the combined processes of kinetic sieving and squeeze expulsion. This generates an inversely graded particle-size distribution, which is fundamental to a variety of pattern formation mechanisms, as well as subtle size-mobility feedback effects, leading to the formation of coarse-grained lateral levees that create channels in geophys...

  2. The effect of particle size and concentration on the flow properties of a homogeneous slurry

    International Nuclear Information System (INIS)

    Abbas, M.A.; Crowe, C.T.

    1986-01-01

    This paper presents the results of the effects of particle size and concentration on the velocity distribution in the fully developed flow of a homogeneous slurry. The slurry consisted of chloroform and silica gel with matched index of refraction to enable Laser-Doppler anemometry (LDA) measurements through the mixture. Slurries with two particle sizes and solids concentration up to 30% by volume were studied. Measurements were made over a Reynolds number range of 1,200 to 30,000

  3. Performance of japanese quails fed feeds containing different corn and limestone particle sizes

    Directory of Open Access Journals (Sweden)

    DA Berto

    2007-09-01

    Full Text Available This study aimed at evaluating performance and egg quality of Japanese quails fed feeds containing different corn and limestone particle sizes. A total number of 648 birds in the peak of production was distributed in a random complete block experimental design, using a 2x3 factorial arrangement (2 corn particle sizes and 3 limestone particle sizes. Birds were designated to one of two blocks, with six replicates of 18 birds each. Mean geometric diameter (MGD values used were 0.617mm and 0.723mm (corn fine and coarse particle sizes, respectively, and 0.361mm, 0.721mm, and 0.947mm (limestone fine, intermediate and coarse particle sizes, respectively. The following treatments were applied: T1: fine corn feed, with 100% fine limestone; T2: fine corn feed, with 50% fine limestone and 50% intermediate limestone; T3: fine corn feed, with 50% fine limestone and 50% coarse limestone; T4: coarse corn feed, with 100% fine limestone; T5: coarse corn feed, with 50% fine limestone and 50% intermediate limestone; T6: coarse corn feed, with 50% fine limestone and 50% coarse limestone. The experiment lasted 112 days, consisting of 4 cycles of 28 days. No significant interaction was observed among corn and limestone particle sizes for any of the analyzed parameters. There were no significant effects (p>0.05 of the tested corn particle sizes on quail performance or egg quality. There were significant (p<0.05 isolated effects of limestone particle size only on the percentage of cracked eggs, which was reduced when birds fed 50% coarse limestone (0.947mm and 50% fine limestone (0.361mm as compared to those fed 100% fine limestone. Therefore, the inclusion of 50% coarse limestone (0.947mm is recommended for quail egg production.

  4. Micrometer sized dust particles in a fr plasma under varying gravity conditions

    NARCIS (Netherlands)

    Beckers, J.; Stoffels, W.W.; Kroesen, G.M.W.; Ockenga, T.; Wolter, M.; Kersten, H.

    2009-01-01

    For diagnostic purposes micrometer-sized particles can be used as floating electrostatic probes. Once injected into a complex rf plasma, these particles will become negatively charged and can be trapped in the plasma sheath due to an equilibrium of several forces working on them, e.g. the

  5. Urban particle size distributions during two contrasting dust events originating from Taklimakan and Gobi Deserts

    International Nuclear Information System (INIS)

    Zhao, Suping; Yu, Ye; Xia, Dunsheng; Yin, Daiying; He, Jianjun; Liu, Na; Li, Fang

    2015-01-01

    The dust origins of the two events were identified using HYSPLIT trajectory model and MODIS and CALIPSO satellite data to understand the particle size distribution during two contrasting dust events originated from Taklimakan and Gobi deserts. The supermicron particles significantly increased during the dust events. The dust event from Gobi desert affected significantly on the particles larger than 2.5 μm, while that from Taklimakan desert impacted obviously on the particles in 1.0–2.5 μm. It is found that the particle size distributions and their modal parameters such as VMD (volume median diameter) have significant difference for varying dust origins. The dust from Taklimakan desert was finer than that from Gobi desert also probably due to other influencing factors such as mixing between dust and urban emissions. Our findings illustrated the capacity of combining in situ, satellite data and trajectory model to characterize large-scale dust plumes with a variety of aerosol parameters. - Highlights: • Dust particle size distributions had large differences for varying origins. • Dust originating from Taklimakan Desert was finer than that from Gobi Desert. • Effect of dust on the supermicron particles was obvious. • PM_1_0 concentrations increased by a factor of 3.4–25.6 during the dust event. - Dust particle size distributions had large differences for varying origins, which may be also related to other factors such as mixing between dust and urban emissions.

  6. Damping of Mechanical Waves with Styrene/Butadiene Rubber Filled with Polystyrene Particle: Effects of Particles Size and Wave Frequency

    Directory of Open Access Journals (Sweden)

    M. Haghgo

    2007-08-01

    Full Text Available Utilizing polymeric materials for damping mechanical waves is of great importance in various fields of applications such as military camouflage, prevention of structural vibrational energy transfer, and noise attenuation. This ability originates from segmental dynamics of chain-like polymer molecules. Damping properties of styrene-butadiene rubbercontaining 10 wt% of monosize polystyrene particles with different diameters (from 80 nm to 500 μm was investigated in the frequency range of vibration, sound, and ultrasound via dynamic mechanical thermal analysis, normalsound adsorption test, and ultrasound attenuation coefficient measurement. The obtained results indicated that for different systems, containing different sizes of polystyrene particles, the area under the damping curve does not show significant change comparing to the neat SBR in the frequency range studied. However, addition of polystyrene particles, specifically nanosized particles, resulted in emergence of a secondary glass transition temperature which could be attributed to the modified dynamics of a layer of matrix molecules near the surface of PS particles. In the range of sound frequency, 0.5 to 6.3 kHz, the maximum damping was observed for the system containing polystyrene nanoparticles. However the single damping curve of neat SBR was separated into two or even three distinct curves owing to the presence of the particles. The maximum damping in the ultrasound frequency range was found for the system containing 0.5 mm polystyrene particles. This is attributed to different contributions from matrix chains dynamics and the reflection of mechanical waves from particles-matrix interface at different frequency ranges. On other words, the increase in the glass transition temperature of the elastomeric matrix phase with increasing the mechanical wave frequency causes a reduction in the contribution from matrix chains dynamics while the contribution due to diffraction from dispersed

  7. Diffusion of finite-sized hard-core interacting particles in a one-dimensional box: Tagged particle dynamics.

    Science.gov (United States)

    Lizana, L; Ambjörnsson, T

    2009-11-01

    We solve a nonequilibrium statistical-mechanics problem exactly, namely, the single-file dynamics of N hard-core interacting particles (the particles cannot pass each other) of size Delta diffusing in a one-dimensional system of finite length L with reflecting boundaries at the ends. We obtain an exact expression for the conditional probability density function rhoT(yT,t|yT,0) that a tagged particle T (T=1,...,N) is at position yT at time t given that it at time t=0 was at position yT,0. Using a Bethe ansatz we obtain the N -particle probability density function and, by integrating out the coordinates (and averaging over initial positions) of all particles but particle T , we arrive at an exact expression for rhoT(yT,t|yT,0) in terms of Jacobi polynomials or hypergeometric functions. Going beyond previous studies, we consider the asymptotic limit of large N , maintaining L finite, using a nonstandard asymptotic technique. We derive an exact expression for rhoT(yT,t|yT,0) for a tagged particle located roughly in the middle of the system, from which we find that there are three time regimes of interest for finite-sized systems: (A) for times much smaller than the collision time tparticle concentration and D is the diffusion constant for each particle, the tagged particle undergoes a normal diffusion; (B) for times much larger than the collision time t >taucoll but times smaller than the equilibrium time ttaue , rhoT(yT,t|yT,0) approaches a polynomial-type equilibrium probability density function. Notably, only regimes (A) and (B) are found in the previously considered infinite systems.

  8. Size-selective sorting in bubble streaming flows: Particle migration on fast time scales

    Science.gov (United States)

    Thameem, Raqeeb; Rallabandi, Bhargav; Hilgenfeldt, Sascha

    2015-11-01

    Steady streaming from ultrasonically driven microbubbles is an increasingly popular technique in microfluidics because such devices are easily manufactured and generate powerful and highly controllable flows. Combining streaming and Poiseuille transport flows allows for passive size-sensitive sorting at particle sizes and selectivities much smaller than the bubble radius. The crucial particle deflection and separation takes place over very small times (milliseconds) and length scales (20-30 microns) and can be rationalized using a simplified geometric mechanism. A quantitative theoretical description is achieved through the application of recent results on three-dimensional streaming flow field contributions. To develop a more fundamental understanding of the particle dynamics, we use high-speed photography of trajectories in polydisperse particle suspensions, recording the particle motion on the time scale of the bubble oscillation. Our data reveal the dependence of particle displacement on driving phase, particle size, oscillatory flow speed, and streaming speed. With this information, the effective repulsive force exerted by the bubble on the particle can be quantified, showing for the first time how fast, selective particle migration is effected in a streaming flow. We acknowledge support by the National Science Foundation under grant number CBET-1236141.

  9. Particle size distribution in effluent of trickling filters and in humus tanks.

    Science.gov (United States)

    Schubert, W; Günthert, F W

    2001-11-01

    Particles and aggregates from trickling filters must be eliminated from wastewater. Usually this happens through sedimentation in humus tanks. Investigations to characterize these solids by way of particle size measurements, image analysis and particle charge measurements (zeta potential) are made within the scope of Research Center for Science and Technology "Fundamentals of Aerobic biological wastewater treatment" (SFB 411). The particle size measuring results given within this report were obtained at the Ingolstadt wastewater treatment plant, Germany, which served as an example. They have been confirmed by similar results from other facilities. Particles flushed out from trickling filters will be partially destroyed on their way to the humus tank. A large amount of small particles is to be found there. On average 90% of the particles are smaller than 30 microm. Particle size plays a decisive role in the sedimentation behaviour of solids. Small particles need sedimentation times that cannot be provided in settling tanks. As a result they cause turbidity in the final effluent. Therefore quality of sewage discharge suffers, and there are hardly advantages of the fixed film reactor treatment compared to the activated sludge process regarding sedimentation behaviour.

  10. Combinative Particle Size Reduction Technologies for the Production of Drug Nanocrystals

    Directory of Open Access Journals (Sweden)

    Jaime Salazar

    2014-01-01

    Full Text Available Nanosizing is a suitable method to enhance the dissolution rate and therefore the bioavailability of poorly soluble drugs. The success of the particle size reduction processes depends on critical factors such as the employed technology, equipment, and drug physicochemical properties. High pressure homogenization and wet bead milling are standard comminution techniques that have been already employed to successfully formulate poorly soluble drugs and bring them to market. However, these techniques have limitations in their particle size reduction performance, such as long production times and the necessity of employing a micronized drug as the starting material. This review article discusses the development of combinative methods, such as the NANOEDGE, H 96, H 69, H 42, and CT technologies. These processes were developed to improve the particle size reduction effectiveness of the standard techniques. These novel technologies can combine bottom-up and/or top-down techniques in a two-step process. The combinative processes lead in general to improved particle size reduction effectiveness. Faster production of drug nanocrystals and smaller final mean particle sizes are among the main advantages. The combinative particle size reduction technologies are very useful formulation tools, and they will continue acquiring importance for the production of drug nanocrystals.

  11. Bioleaching of metals from spent refinery petroleum catalyst using moderately thermophilic bacteria: effect of particle size.

    Science.gov (United States)

    Srichandan, Haragobinda; Singh, Sradhanjali; Pathak, Ashish; Kim, Dong-Jin; Lee, Seoung-Won; Heyes, Graeme

    2014-01-01

    The present work investigated the leaching potential of moderately thermophilic bacteria in the recovery of metals from spent petroleum catalyst of varying particle sizes. The batch bioleaching experiments were conducted by employing a mixed consortium of moderate thermophilic bacteria at 45°C and by using five different particle sizes (from 45 to >2000 μm) of acetone-washed spent catalyst. The elemental mapping by FESEM confirmed the presence of Al, Ni, V and Mo along with sulfur in the spent catalyst. During bioleaching, Ni (92-97%) and V (81-91%) were leached in higher concentrations, whereas leaching yields of Al (23-38%) were found to be lowest in all particle sizes investigated. Decreasing the particle size from >2000 μm to 45-106 μm caused an increase in leaching yields of metals during initial hours. However, the final metals leaching yields were almost independent of particle sizes of catalyst. Leaching kinetics was observed to follow the diffusion-controlled model showing the linearity more close than the chemical control. The results of the present study suggested that bioleaching using moderate thermophilic bacteria was highly effective in removing the metals from spent catalyst. Moreover, bioleaching can be conducted using spent catalyst of higher particle size (>2000 μm), thus saving the grinding cost and making process attractive for larger scale application.

  12. 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

  13. Effect of particle size on thermal decomposition of alkali metal picrates

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rui; Zhang, Tonglai, E-mail: ztlbit@bit.edu.cn; Yang, Li; Zhou, Zunning

    2014-05-01

    Graphical abstract: The smaller-sized picrate has greater gas emission than do its larger counterpart. The small size effect reduces the thermal decomposition activation energy, accelerates the reaction rate, and promotes the reaction activity. - Highlights: • Picrates were prepared into three micron sizes by microemulsion synthesis. • Thermal decomposition kinetics and thermodynamics were studied by DPTA and DSC. • Smaller-sized picrate has higher activity and faster reaction rate. • Particle size effect on thermal decomposition kinetics and thermodynamics was revealed. - Abstract: Three alkali metal picrates, KPA, RbPA and CsPA, were prepared into three micron sizes by microemulsion synthesis, and their thermal decomposition behaviors were investigated by DPTA at different temperatures and by DSC at different heating rates. The smaller-sized picrate has greater gas emission and smaller kinetic and thermodynamic parameters than do its larger counterpart. It can be attributed to the decreasing particle size which leads to the high surface energy, the fast mass and heat transfer, and the increasing active sites on the reaction interface. The small size effect and surface effect cause the autocatalysis which reduces the activation energy and promotes the reaction activity. The particle size does not affect the reaction mechanism. However, the picrates with different central alkali metals exhibit different reaction mechanisms even though they are of the same size. This is because the central metal determines the bond energy and consequently affects the stability of picrate.

  14. Effect of particle size on thermal decomposition of alkali metal picrates

    International Nuclear Information System (INIS)

    Liu, Rui; Zhang, Tonglai; Yang, Li; Zhou, Zunning

    2014-01-01

    Graphical abstract: The smaller-sized picrate has greater gas emission than do its larger counterpart. The small size effect reduces the thermal decomposition activation energy, accelerates the reaction rate, and promotes the reaction activity. - Highlights: • Picrates were prepared into three micron sizes by microemulsion synthesis. • Thermal decomposition kinetics and thermodynamics were studied by DPTA and DSC. • Smaller-sized picrate has higher activity and faster reaction rate. • Particle size effect on thermal decomposition kinetics and thermodynamics was revealed. - Abstract: Three alkali metal picrates, KPA, RbPA and CsPA, were prepared into three micron sizes by microemulsion synthesis, and their thermal decomposition behaviors were investigated by DPTA at different temperatures and by DSC at different heating rates. The smaller-sized picrate has greater gas emission and smaller kinetic and thermodynamic parameters than do its larger counterpart. It can be attributed to the decreasing particle size which leads to the high surface energy, the fast mass and heat transfer, and the increasing active sites on the reaction interface. The small size effect and surface effect cause the autocatalysis which reduces the activation energy and promotes the reaction activity. The particle size does not affect the reaction mechanism. However, the picrates with different central alkali metals exhibit different reaction mechanisms even though they are of the same size. This is because the central metal determines the bond energy and consequently affects the stability of picrate

  15. In Situ Sampling of Relative Dust Devil Particle Loads and Their Vertical Grain Size Distributions.

    Science.gov (United States)

    Raack, Jan; Reiss, Dennis; Balme, Matthew R; Taj-Eddine, Kamal; Ori, Gian Gabriele

    2017-04-19

    During a field campaign in the Sahara Desert in southern Morocco, spring 2012, we sampled the vertical grain size distribution of two active dust devils that exhibited different dimensions and intensities. With these in situ samples of grains in the vortices, it was possible to derive detailed vertical grain size distributions and measurements of the lifted relative particle load. Measurements of the two dust devils show that the majority of all lifted particles were only lifted within the first meter (∼46.5% and ∼61% of all particles; ∼76.5 wt % and ∼89 wt % of the relative particle load). Furthermore, ∼69% and ∼82% of all lifted sand grains occurred in the first meter of the dust devils, indicating the occurrence of "sand skirts." Both sampled dust devils were relatively small (∼15 m and ∼4-5 m in diameter) compared to dust devils in surrounding regions; nevertheless, measurements show that ∼58.5% to 73.5% of all lifted particles were small enough to go into suspension (grain size classification). This relatively high amount represents only ∼0.05 to 0.15 wt % of the lifted particle load. Larger dust devils probably entrain larger amounts of fine-grained material into the atmosphere, which can have an influence on the climate. Furthermore, our results indicate that the composition of the surface, on which the dust devils evolved, also had an influence on the particle load composition of the dust devil vortices. The internal particle load structure of both sampled dust devils was comparable related to their vertical grain size distribution and relative particle load, although both dust devils differed in their dimensions and intensities. A general trend of decreasing grain sizes with height was also detected. Key Words: Mars-Dust devils-Planetary science-Desert soils-Atmosphere-Grain sizes. Astrobiology 17, xxx-xxx.

  16. Particle size distribution properties in mixed-phase monsoon clouds from in situ measurements during CAIPEEX

    Science.gov (United States)

    Patade, Sachin; Prabha, T. V.; Axisa, D.; Gayatri, K.; Heymsfield, A.

    2015-10-01

    A comprehensive analysis of particle size distributions measured in situ with airborne instrumentation during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) is presented. In situ airborne observations in the developing stage of continental convective clouds during premonsoon (PRE), transition, and monsoon (MON) period at temperatures from 25 to -22°C are used in the study. The PRE clouds have narrow drop size and particle size distributions compared to monsoon clouds and showed less development of size spectra with decrease in temperature. Overall, the PRE cases had much lower values of particle number concentrations and ice water content compared to MON cases, indicating large differences in the ice initiation and growth processes between these cloud regimes. This study provided compelling evidence that in addition to dynamics, aerosol and moisture are important for modulating ice microphysical processes in PRE and MON clouds through impacts on cloud drop size distribution. Significant differences are observed in the relationship of the slope and intercept parameters of the fitted particle size distributions (PSDs) with temperature in PRE and MON clouds. The intercept values are higher in MON clouds than PRE for exponential distribution which can be attributed to higher cloud particle number concentrations and ice water content in MON clouds. The PRE clouds tend to have larger values of dispersion of gamma size distributions than MON clouds, signifying narrower spectra. The relationships between PSDs parameters are presented and compared with previous observations.

  17. Early-stage evolution of particle size distribution with Johnson's SB function due to Brownian coagulation

    International Nuclear Information System (INIS)

    Tang Hong; Lin Jianzhong

    2013-01-01

    The moment method can be used to determine the time evolution of particle size distribution due to Brownian coagulation based on the general dynamic equation (GDE). But the function form of the initial particle size distribution must be determined beforehand for the moment method. If the assumed function type of the initial particle size distribution has an obvious deviation from the true particle population, the evolution of particle size distribution may be different from the real evolution tendency. Thus, a simple and general method is proposed based on the moment method. In this method, the Johnson's S B function is chosen as a general distribution function to fit the initial distributions including the log normal (L-N), Rosin–Rammler (R-R), normal (N-N) and gamma distribution functions, respectively. Meanwhile, using the modified beta function to fit the L-N, R-R, N-N and gamma functions is also conducted as a comparison in order to present the advantage of the Johnson's S B function as the general distribution function. And then, the time evolution of particle size distributions using the Johnson's S B function as the initial distribution can be obtained by several lower order moment equations of the Johnson's S B function in conjunction with the GDE during the Brownian coagulation process. Simulation experiments indicate that fairly reasonable results of the time evolution of particle size distribution can be obtained with this proposed method in the free molecule regime, transition regime and continuum plus near continuum regime, respectively, at the early time stage of evolution. The Johnson's S B function has the ability of describing the early time evolution of different initial particle size distributions. (paper)

  18. Polypyrrole-palladium nanocomposite coating of micrometer-sized polymer particles toward a recyclable catalyst.

    Science.gov (United States)

    Fujii, Syuji; Matsuzawa, Soichiro; Hamasaki, Hiroyuki; Nakamura, Yoshinobu; Bouleghlimat, Azzedine; Buurma, Niklaas J

    2012-02-07

    A range of near-monodisperse, multimicrometer-sized polymer particles has been coated with ultrathin overlayers of polypyrrole-palladium (PPy-Pd) nanocomposite by chemical oxidative polymerization of pyrrole using PdCl(2) as an oxidant in aqueous media. Good control over the targeted PPy-Pd nanocomposite loading is achieved for 5.2 μm diameter polystyrene (PS) particles, and PS particles of up to 84 μm diameter can also be efficiently coated with the PPy-Pd nanocomposite. The seed polymer particles and resulting composite particles were extensively characterized with respect to particle size and size distribution, morphology, surface/bulk chemical compositions, and conductivity. Laser diffraction studies of dilute aqueous suspensions indicate that the polymer particles disperse stably before and after nanocoating with the PPy-Pd nanocomposite. The Fourier transform infrared (FT-IR) spectrum of the PS particles coated with the PPy-Pd nanocomposite overlayer is dominated by the underlying particle, since this is the major component (>96% by mass). Thermogravimetric and elemental analysis indicated that PPy-Pd nanocomposite loadings were below 6 wt %. The conductivity of pressed pellets prepared with the nanocomposite-coated particles increased with a decrease of particle diameter because of higher PPy-Pd nanocomposite loading. "Flattened ball" morphologies were observed by scanning/transmission electron microscopy after extraction of the PS component from the composite particles, which confirmed a PS core and a PPy-Pd nanocomposite shell morphology. X-ray diffraction confirmed the production of elemental Pd and X-ray photoelectron spectroscopy studies indicated the existence of elemental Pd on the surface of the composite particles. Transmission electron microscopy confirmed that nanometer-sized Pd particles were distributed in the shell. Near-monodisperse poly(methyl methacrylate) particles with diameters ranging between 10 and 19 μm have been also successfully

  19. 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

    Measurements of solute dispersion in porous media is generally much more time consuming than gas dispersion measurements performed under equivalent conditions. Significant time savings may therefore, be achieved if solute dispersion coefficients can be estimated based on measured gas dispersion...... data. This paper evaluates the possibility for estimating solute dispersion based on gas dispersion measurements. Breakthrough measurements were carried out at different fluid velocities (covering the same range in Reynolds number), using O2 and NaCl as gas and solute tracers, respectively. Three...... different, granular porous materials were used: (1) crushed granite (very angular particles), (2) gravel (particles of intermediate roundness) and (3) Leca® (almost spherical particles). For each material, 21 different particle size fractions were used. Gas and solute dispersion coefficients were determined...

  20. Mechanism for Particle Transport and Size Sorting via Low-Frequency Vibrations

    Science.gov (United States)

    Sherrit, Stewart; Scott, James S.; Bar-Cohen, Yoseph; Badescu, Mircea; Bao, Xiaoqi

    2010-01-01

    There is a need for effective sample handling tools to deliver and sort particles for analytical instruments that are planned for use in future NASA missions. Specifically, a need exists for a compact mechanism that allows transporting and sieving particle sizes of powdered cuttings and soil grains that may be acquired by sampling tools such as a robotic scoop or drill. The required tool needs to be low mass and compact to operate from such platforms as a lander or rover. This technology also would be applicable to sample handling when transporting samples to analyzers and sorting particles by size.

  1. Dimerization of eosin on nanostructured gold surfaces: Size regime dependence of the small metallic particles

    Science.gov (United States)

    Ghosh, Sujit Kumar; Pal, Anjali; Nath, Sudip; Kundu, Subrata; Panigrahi, Sudipa; Pal, Tarasankar

    2005-08-01

    Gold nanoparticles of variable sizes have been exploited to study their influence on the absorption and emission spectral characteristics of eosin, a fluorescent dye. It has been found that smaller particles of gold stimulate J-aggregation of eosin on the surface of metal particles whereas larger particles cannot induce any kind of aggregation amongst the dye molecules. The size regime dependence of the gold nanoparticles has been attributed to the intercluster interactions induced by the dye molecules for smaller gold nanoparticles and consequently, close packing of the dye molecules around the gold surface engenders intermolecular interactions amongst the dye molecules leading to dimerization.

  2. Influence of removal time and particle size on the particle substrate adhesion force

    Directory of Open Access Journals (Sweden)

    M. A. Felicetti

    2008-03-01

    Full Text Available An investigation was conducted on influence of removal time on the particle substrate adhesive force. The centrifuge technique was used to determine the adhesion force at different compression and removal rates. A microcentrifuge with a maximum rotation of 14000 rpm was used to both compress upon particles and remove them from the surface of the substrate. An image analysis program (Image-Pro Plus 4.5 was employed to monitor the number of particles adhering to and removed from the surface of the substrate after each increase in angular speed. The influence of removal time on the adhesion force was investigated, using removal times of 1, 3 and 5 minutes, which indicated that removal time does not interfere with the adhesion force within the diameter range analyzed here.

  3. Gold particle formation via photoenhanced deposition on lithium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Zaniewski, A.M., E-mail: azaniews@asu.edu; Meeks, V.; Nemanich, R.J.

    2017-05-31

    Highlights: • Gold chloride is reduced into solid gold nanoparticles at the surface of a polarized semiconductor. • Reduction processes are driven by ultraviolet light. • Gold nanoparticle and silver nanoparticle deposition patterns are compared. - Abstract: In this work, we report on a technique to reduce gold chloride into sub-micron particles and nanoparticles. We use photoelectron transfer from periodically polarized lithium niobate (PPLN) illuminated with above band gap light to drive the surface reactions required for the reduction and particle formation. The particle sizes and distributions on the PPLN surface are sensitive to the solution concentration, with inhibited nucleation and large particles (>150 nm) for both low (2E−8M to 9E−7M) and high (1E−5M to 1E−3M) concentrations of gold chloride. At midrange values of the concentration, nucleation is more frequent, resulting in smaller sized particles (<150 nm). We compare the deposition process to that for silver, which has been previously studied. We find that the reduction of gold chloride into nanoparticles is inhibited compared to silver ion reduction, due to the multi-step reaction required for gold particle formation. This also has consequences for the resulting deposition patterns: while silver deposits into nanowires along boundaries between areas with opposite signed polarizations, such patterning of the deposition is not observed for gold, for a wide range of concentrations studied (2E−8 to 1E−3M).

  4. [Size distribution of particle and polycyclic aromatic hydrocarbons in particle emissions from simulated emission sources].

    Science.gov (United States)

    Fu, Hai-Huan; Tian, Na; Shang, Hui-Bin; Zhang, Bin; Ye, Su-Fen; Chen, Xiao-Qiu; Wu, Shui-Ping

    2014-01-01

    Particles from cooking lampblack, biomass and plastics burning smoke, gasoline vehicular exhausts and gasoline generator exhausts were prepared in a resuspension test chamber and collected using a cascade MOUDI impactor. A total of 18 polycyclic aromatic hydrocarbons (PAHs) associated with particles were analyzed by GC-MS. The results showed that there were two peaks in the range of 0.44-1.0 microm and 2.5-10 microm for cooking lampblack, and only one peak in the range of 0.44-1.0 microm for straw and wood burning smoke. But there were no clear peak for plastics burning smoke. The peak for gasoline vehicular exhausts was found in the range of 2.5-10 microm due to the influence of water vapor associated with particles, while the particles from gasoline generator exhausts were mainly in the range of lampblack and gasoline vehicular exhausts. The peak in the range of 0.44-1.0 microm became more and more apparent with the increase of PAHs molecular weight. The fraction of PAH on particles less than 1.0 microm to that on the total particles increased along with PAH's molecular weight. Phenanthrene was the dominant compound for cooking lampblack and combustion smoke, while gasoline vehicular exhausts and generator exhausts were characterized with significantly high levels of naphthalene and benzo[g, h, i] perylene, respectively. The distribution of source characteristic ratios indicated that PAHs from cooking lampblack and biomass burning were close and they were different from those of vehicular exhausts and generator exhausts.

  5. Measurement of particle size distribution of soil and selected aggregate sizes using the hydrometer method and laser diffractometry

    Science.gov (United States)

    Guzmán, G.; Gómez, J. A.; Giráldez, J. V.

    2010-05-01

    Soil particle size distribution has been traditionally determined by the hydrometer or the sieve-pipette methods, both of them time consuming and requiring a relatively large soil sample. This might be a limitation in situations, such as for instance analysis of suspended sediment, when the sample is small. A possible alternative to these methods are the optical techniques such as laser diffractometry. However the literature indicates that the use of this technique as an alternative to traditional methods is still limited, because the difficulty in replicating the results obtained with the standard methods. In this study we present the percentages of soil grain size determined using laser diffractometry within ranges set between 0.04 - 2000 μm. A Beckman-Coulter ® LS-230 with a 750 nm laser beam and software version 3.2 in five soils, representative of southern Spain: Alameda, Benacazón, Conchuela, Lanjarón and Pedrera. In three of the studied soils (Alameda, Benacazón and Conchuela) the particle size distribution of each aggregate size class was also determined. Aggregate size classes were obtained by dry sieve analysis using a Retsch AS 200 basic ®. Two hundred grams of air dried soil were sieved during 150 s, at amplitude 2 mm, getting nine different sizes between 2000 μm and 10 μm. Analyses were performed by triplicate. The soil sample preparation was also adapted to our conditions. A small amount each soil sample (less than 1 g) was transferred to the fluid module full of running water and disaggregated by ultrasonication at energy level 4 and 80 ml of sodium hexametaphosphate solution during 580 seconds. Two replicates of each sample were performed. Each measurement was made for a 90 second reading at a pump speed of 62. After the laser diffractometry analysis, each soil and its aggregate classes were processed calibrating its own optical model fitting the optical parameters that mainly depends on the color and the shape of the analyzed particle. As a

  6. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts

    International Nuclear Information System (INIS)

    Babu, S. Suresh; Kompalli, Sobhan Kumar; Moorthy, K. Krishna

    2016-01-01

    Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~ 15–15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter < 100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

  7. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts

    Energy Technology Data Exchange (ETDEWEB)

    Babu, S. Suresh, E-mail: s_sureshbabu@vssc.gov.in [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Kompalli, Sobhan Kumar [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Moorthy, K. Krishna [Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012 (India)

    2016-09-01

    Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~ 15–15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter < 100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

  8. Effect of indirect non-thermal plasma on particle size distribution and composition of diesel engine particles

    Science.gov (United States)

    Linbo, GU; Yixi, CAI; Yunxi, SHI; Jing, WANG; Xiaoyu, PU; Jing, TIAN; Runlin, FAN

    2017-11-01

    To explore the effect of the gas source flow rate on the actual diesel exhaust particulate matter (PM), a test bench for diesel engine exhaust purification was constructed, using indirect non-thermal plasma technology. The effects of different gas source flow rates on the quantity concentration, composition, and apparent activation energy of PM were investigated, using an engine exhaust particle sizer and a thermo-gravimetric analyzer. The results show that when the gas source flow rate was large, not only the maximum peak quantity concentrations of particles had a large drop, but also the peak quantity concentrations shifted to smaller particle sizes from 100 nm to 80 nm. When the gas source flow rate was 10 L min-1, the total quantity concentration greatly decreased where the removal rate of particles was 79.2%, and the variation of the different mode particle proportion was obvious. Non-thermal plasma (NTP) improved the oxidation ability of volatile matter as well as that of solid carbon. However, the NTP gas source rate had little effects on oxidation activity of volatile matter, while it strongly influenced the oxidation activity of solid carbon. Considering the quantity concentration and oxidation activity of particles, a gas source flow rate of 10 L min-1 was more appropriate for the purification of particles.

  9. Approach for measuring the chemistry of individual particles in the size range critical for cloud formation.

    Science.gov (United States)

    Zauscher, Melanie D; Moore, Meagan J K; Lewis, Gregory S; Hering, Susanne V; Prather, Kimberly A

    2011-03-15

    Aerosol particles, especially those ranging from 50 to 200 nm, strongly impact climate by serving as nuclei upon which water condenses and cloud droplets form. However, the small number of analytical methods capable of measuring the composition of particles in this size range, particularly at the individual particle level, has limited our knowledge of cloud condensation nuclei (CCN) composition and hence our understanding of aerosols effect on climate. To obtain more insight into particles in this size range, we developed a method which couples a growth tube (GT) to an ultrafine aerosol time-of-flight mass spectrometer (UF-ATOFMS), a combination that allows in situ measurements of the composition of individual particles as small as 38 nm. The growth tube uses water to grow particles to larger sizes so they can be optically detected by the UF-ATOFMS, extending the size range to below 100 nm with no discernible changes in particle composition. To gain further insight into the temporal variability of aerosol chemistry and sources, the GT-UF-ATOFMS was used for online continuous measurements over a period of 3 days.

  10. Investigation of the low-speed impact behavior of dual particle size metal matrix composites

    International Nuclear Information System (INIS)

    Cerit, Afşın Alper

    2014-01-01

    Highlights: • AA2124 matrix composites reinforced with SiC particles were manufactured. • Low-speed impact behaviors of composites were investigated. • Composites were manufactured with single (SPS) and dual particle sizes (DPS). • Impact behaviors of DPS composites are more favorable than the SPS composites. • Approximately 50–60% of input energy was absorbed by the composite samples. - Abstract: SiC-reinforced aluminum matrix composites were manufactured by powder metallurgy using either single or dual particle sized SiC powders and samples sintered under argon atmosphere. Quasi-static loading, low-speed impact tests and hardness tests were used to investigate mechanical behavior and found that dual particle size composites had improved hardness and impact performance compared to single particle size composites. Sample microstructure, particle distributions, plastic deformations and post-testing damages were examined by scanning electron microscopy and identified microstructure agglomerations in SPS composites. Impact traces were characterized by broken and missing SiC particles and plastically deformed composite areas

  11. Removal of virus to protozoan sized particles in point-of-use ceramic water filters.

    Science.gov (United States)

    Bielefeldt, Angela R; Kowalski, Kate; Schilling, Cherylynn; Schreier, Simon; Kohler, Amanda; Scott Summers, R

    2010-03-01

    The particle removal performance of point-of-use ceramic water filters (CWFs) was characterized in the size range of 0.02-100 microm using carboxylate-coated polystyrene fluorescent microspheres, natural particles and clay. Particles were spiked into dechlorinated tap water, and three successive water batches treated in each of six different CWFs. Particle removal generally increased with increasing size. The removal of virus-sized 0.02 and 0.1 microm spheres were highly variable between the six filters, ranging from 63 to 99.6%. For the 0.5 microm spheres removal was less variable and in the range of 95.1-99.6%, while for the 1, 2, 4.5, and 10 microm spheres removal was >99.6%. Recoating four of the CWFs with colloidal silver solution improved removal of the 0.02 microm spheres, but had no significant effects on the other particle sizes. Log removals of 1.8-3.2 were found for natural turbidity and spiked kaolin clay particles; however, particles as large as 95 microm were detected in filtered water. Copyright 2009 Elsevier Ltd. All rights reserved.

  12. Zn incorporation in CuInSe2: Particle size and strain effects on ...

    Indian Academy of Sciences (India)

    Administrator

    Zn incorporation in CuInSe2: Particle size and strain effects on microstructural ... size as well as tensile strain. The calculated ... X-ray diffraction analysis of CuInSe2 samples reported in figure 2 ... To estimate qualitative information regarding ...

  13. U-Mo Alloy Powder Obtained Through Selective Hydriding. Particle Size Control

    International Nuclear Information System (INIS)

    Balart, S.N.; Bruzzoni, P.; Granovsky, M.S.

    2002-01-01

    Hydride-dehydride methods to obtain U-Mo alloy powder for high-density fuel elements have been successfully tested by different authors. One of these methods is the selective hydriding of the α phase (HSα). In the HSα method, a key step is the partial decomposition of the γ phase (retained by quenching) to α phase and an enriched γ phase or U 2 Mo. This transformation starts mainly at grain boundaries. Subsequent hydrogenation of this material leads to selective hydriding of the α phase, embrittlement and intergranular fracture. According to this picture, the particle size of the final product should be related to the γ grain size of the starting alloy. The feasibility of controlling the particle size of the product by changing the γ grain size of the starting alloy is currently investigated. In this work an U-7 wt% Mo alloy was subjected to various heat treatments in order to obtain different grain sizes. The results on the powder particle size distribution after applying the HSα method to these samples show that there is a strong correlation between the original γ grain size and the particle size distribution of the powder. (author)

  14. Variations in Tropospheric Submicron Particle Size Distributions Across the European Continent 2008–2009

    Czech Academy of Sciences Publication Activity Database

    Beddows, D.C.S.; Dall’Osto, M.; Harrison, R. M.; Kulmala, M.; Asmi, A.; Wiedensohler, A.; Laj, P.; Fjaeraa, A.M.; Sellegri, K.; Birmili, W.; Bukowiecki, N.; Weingartner, E.; Baltensperger, U.; Ždímal, Vladimír; Zíková, Naděžda; Putaud, J.-P.; Marinoni, A.; Tunved, P.; Hansson, H.-C.; Feibig, M.; Kivekäs, N.; Swietlicki, E.; Lihavainen, H.; Asmi, E.; Ulevicius, V.; Aalto, P.P.; Mihalopoulos, N.; Kalivitis, N.; Kalapov, I.; Kiss, G.; de Leeuw, G.; Henzing, B.; O'Dowd, C.; Jennings, S.G.; Flentje, H.; Meinhardt, F.; Ries, L.; Denier van der Gon19, H.A.C.; Visschedijk, A.J.H.; Swietlicki, E.

    2014-01-01

    Roč. 14, č. 8 (2014), s. 4327-4348 ISSN 1680-7316 EU Projects: European Commission(XE) 36833 - EUCAARI; European Commission(XE) 26140 - EUSAAR Institutional support: RVO:67985858 Keywords : particle size distribution * clusters * aerosol size distribution Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.053, year: 2014

  15. Determination of particle size distribution of salt crystals in aqueous slurries

    International Nuclear Information System (INIS)

    Miller, A.G.

    1977-10-01

    A method for determining particle size distribution of water-soluble crystals in aqueous slurries is described. The salt slurries, containing sodium salts of predominantly nitrate, but also nitrite, sulfate, phosphate, aluminates, carbonate, and hydroxide, occur in radioactive, concentrated chemical waste from the reprocessing of nuclear fuel elements. The method involves separating the crystals from the aqueous phase, drying them, and then dispersing the crystals in a nonaqueous medium based on nitroethane. Ultrasonic treatment is important in dispersing the sample into its fundamental crystals. The dispersed crystals are sieved into appropriate size ranges for counting with a HIAC brand particle counter. A preponderance of very fine particles in a slurry was found to increase the difficulty of effecting complete dispersion of the crystals because of the tendency to retain traces of aqueous mother liquor. Traces of moisture produce agglomerates of crystals, the extent of agglomeration being dependent on the amount of moisture present. The procedure is applicable to particles within the 2 to 600 μm size range of the HIAC particle counter. The procedure provides an effective means for measuring particle size distribution of crystals in aqueous salt slurries even when most crystals are less than 10 μm in size. 19 figures

  16. Soot particle size measurements in ethylene diffusion flames at elevated pressures

    KAUST Repository

    Steinmetz, Scott

    2016-05-07

    Soot particle size is investigated in laminar nitrogen-diluted ethylene coflow diffusion flames at 4, 8, 12 and 16 atm. Line of sight attenuation and scattering are used to measure two-dimensional soot volume fraction and particle size fields for the first time at elevated pressures. Soot volume fraction dependence on pressure is consistent with the observations of similar studies, scaling approximately with the square of pressure. Scattering intensity is analyzed through Rayleigh and Rayleigh-Debye-Gans polydisperse fractal aggregate theories to provide two estimates of particle size. An increase in overall particle sizes with pressure is found, consistent with similar one-dimensional studies. Particle diameters in the annulus of the flame increase faster with pressure than those on centerline. Contrary to previous studies, the dependence of particle size on pressure was found to taper off between 8 and 12 atm, with little observed growth beyond 12 atm. The measurements provide additional data for one of the International Sooting Flame (ISF) workshop\\'s target pressurized flames.

  17. Aerosol particle size does not predict pharmacokinetic determined lung dose in children

    DEFF Research Database (Denmark)

    Bønnelykke, Klaus; Chawes, Bo L K; Vindfeld, Signe

    2013-01-01

    In vitro measures of aerosol particles size, such as the fine particle mass, play a pivotal role for approval of inhaled anti-asthmatic drugs. However, the validity as a measure of dose to the lungs in children lacks evidence. In this study we investigated for the first time the association between...... an in vivo estimate of lung dose of inhaled drug in children and the corresponding particle size segments assessed ex vivo. Lung dose of fluticasone propionate after inhalation from a dry powder inhaler (Diskus®) was studied in 23 children aged 4-7 and 12-15 years with mild asthma. Six-hour pharmacokinetics...... was assessed after single inhalation. The corresponding emitted mass of drug in segments of aerosol particle size was assessed ex vivo by replicating the inhalation flows recorded by transducers built into the Diskus® inhaler and re-playing them in a breathing simulator. There was no correlation between any...

  18. Fabrication and Application of Mono-sized Spherical Micro Particles by Pulsated Orifice Ejection Method

    Directory of Open Access Journals (Sweden)

    DONG Wei

    2018-02-01

    Full Text Available A novel technology called pulsated orifice ejection method(POEM and used for preparing mono-sized and high-precision spherical micro particles was introduced in this article. The working principle of the technique was illustrated and it was in two modes:low-melting point diaphragm mode and high-melting point rod mode, depending on the different melting points of materials. The particles prepared by POEM have the advantages of mono-sized, uniform and controllable particle size, high sphericity, and consistent thermal history. By introducing the application of particles prepared by this method, showing the huge application prospects of this technology in electronic packaging, bioengineering, micro-fabrication, rapid solidification analysis of metal droplets, additive manufacturing and so on.With the development of POEM, this technology is predicted to have wider prospects due to its unique characteristics.

  19. Improved soil particle-size analysis by gamma-ray attenuation

    International Nuclear Information System (INIS)

    Oliveira, J.C.M.; Vaz, C.M.P.; Reichardt, K.; Swartzendruber, D.

    1997-01-01

    The size distribution of particles is useful for physical characterization of soil. This study was conducted to determine whether a new method of soil particle-size analysis by gamma-ray attenuation could be further improved by changing the depth and time of measurement of the suspended particle concentration during sedimentation. In addition to the advantage of nondestructive, undisturbed measurement by gamma-ray attenuation, as compared with conventional pipette or hydrometer methods, the modifications here suggested and employed do substantially decrease the total time for analysis, and will also facilitate total automation and generalize the method for other sedimentation studies. Experimental results are presented for three different Brazilian soil materials, and illustrate the nature of the fine detail provided in the cumulative particle-size distribution as given by measurements obtained during the relatively short time period of 28 min

  20. Development of laboratory and process sensors to monitor particle size distribution of industrial slurries

    Energy Technology Data Exchange (ETDEWEB)

    Pendse, H.P.

    1992-10-01

    In this paper we present a novel measurement technique for monitoring particle size distributions of industrial colloidal slurries based on ultrasonic spectroscopy and mathematical deconvolution. An on-line sensor prototype has been developed and tested extensively in laboratory and production settings using mineral pigment slurries. Evaluation to date shows that the sensor is capable of providing particle size distributions, without any assumptions regarding their functional form, over diameters ranging from 0.1 to 100 micrometers in slurries with particle concentrations of 10 to 50 volume percents. The newly developed on-line sensor allows one to obtain particle size distributions of commonly encountered inorganic pigment slurries under industrial processing conditions without dilution.

  1. Effects of cement particle size distribution on performance properties of Portland cement-based materials

    Energy Technology Data Exchange (ETDEWEB)

    Bentz, D.P.; Garboczi, E.J.; Haecker, C.J.; Jensen, O.M.

    1999-10-01

    The original size, spatial distribution, and composition of Portland cement particles have a large influence on hydration kinetics, microstructure development, and ultimate properties of cement-based materials. In this paper, the effects of cement particle size distribution on a variety of performance properties are explored via computer simulation and a few experimental studies. Properties examined include setting time, heat release, capillary porosity percolation, diffusivity, chemical shrinkage, autogenous shrinkage, internal relative humidity evolution, and interfacial transition zone microstructure. The effects of flocculation and dispersion of the cement particles in the starting microstructures on resultant properties are also briefly evaluated. The computer simulations are conducted using two cement particle size distributions that bound those commonly in use today and three different water-to-cement ratios: 0.5, 0.3, and 0.246. For lower water-to-cement ratio systems, the use of coarser cements may offer equivalent or superior performance, as well as reducing production costs for the manufacturer.

  2. Prediction of the filtrate particle size distribution from the pore size distribution in membrane filtration: Numerical correlations from computer simulations

    Science.gov (United States)

    Marrufo-Hernández, Norma Alejandra; Hernández-Guerrero, Maribel; Nápoles-Duarte, José Manuel; Palomares-Báez, Juan Pedro; Chávez-Rojo, Marco Antonio

    2018-03-01

    We present a computational model that describes the diffusion of a hard spheres colloidal fluid through a membrane. The membrane matrix is modeled as a series of flat parallel planes with circular pores of different sizes and random spatial distribution. This model was employed to determine how the size distribution of the colloidal filtrate depends on the size distributions of both, the particles in the feed and the pores of the membrane, as well as to describe the filtration kinetics. A Brownian dynamics simulation study considering normal distributions was developed in order to determine empirical correlations between the parameters that characterize these distributions. The model can also be extended to other distributions such as log-normal. This study could, therefore, facilitate the selection of membranes for industrial or scientific filtration processes once the size distribution of the feed is known and the expected characteristics in the filtrate have been defined.

  3. A method for detecting the presence of organic fraction in nucleation mode sized particles

    Directory of Open Access Journals (Sweden)

    P. Vaattovaara

    2005-01-01

    Full Text Available New particle formation and growth has a very important role in many climate processes. However, the overall knowlegde of the chemical composition of atmospheric nucleation mode (particle diameter, d<20 nm and the lower end of Aitken mode particles (d≤50 nm is still insufficient. In this work, we have applied the UFO-TDMA (ultrafine organic tandem differential mobility analyzer method to shed light on the presence of an organic fraction in the nucleation mode size class in different atmospheric environments. The basic principle of the organic fraction detection is based on our laboratory UFO-TDMA measurements with organic and inorganic compounds. Our laboratory measurements indicate that the usefulness of the UFO-TDMA in the field experiments would arise especially from the fact that atmospherically the most relevant inorganic compounds do not grow in subsaturated ethanol vapor, when particle size is 10 nm in diameter and saturation ratio is about 86% or below it. Furthermore, internally mixed particles composed of ammonium bisulfate and sulfuric acid with sulfuric acid mass fraction ≤33% show no growth at 85% saturation ratio. In contrast, 10 nm particles composed of various oxidized organic compounds of atmospheric relevance are able to grow in those conditions. These discoveries indicate that it is possible to detect the presence of organics in atmospheric nucleation mode sized particles using the UFO-TDMA method. In the future, the UFO-TDMA is expected to be an important aid to describe the composition of atmospheric newly-formed particles.

  4. Optimization of solid state fermentation of sugar cane by Aspergillus niger considering particles size effect

    Energy Technology Data Exchange (ETDEWEB)

    Echevarria, J.; Rodriguez, L.J.A.; Delgado, G. (Instituto Cubano de Investigaciones de los Derivados de la Cana de Azucar (ICIDCA), La Habana (Cuba)); Espinosa, M.E. (Centro Nacional de Investigaciones Cientificas, La Habana (Cuba))

    1991-01-01

    The protein enrichment of sugar cane by solid state fermentation employing Aspergillus niger was optimized in a packed bed column using a two Factor Central Composit Design {alpha} = 2, considering as independent factors the particle diameter corresponding to different times of grinding for a sample and the air flow rate. It was significative for the air flow rate (optimum 4.34 VKgM) and the particle diameter (optimum 0.136 cm). The average particle size distribution, shape factor, specific surface, volume-surface mean diameter, number of particles, real and apparent density and holloweness for the different times of grinding were determined, in order to characterize the samples. (orig.).

  5. The IBAS image analyser and its use in particle size measurement

    International Nuclear Information System (INIS)

    Snelling, K.W.

    1984-10-01

    The Kontron image analyser (IBAS) is used at Winfrith primarily for size analysis of aerosol particles. The system incorporates two computers, IBAS 1 for system communication and control, and IBAS 2 containing the main image memories. The first is accessed via a keyboard or digitiser tablet, and output can be displayed on a monitor or in printed form. The contents of the image memories are displayed on a colour monitor. Automatic image analysis is described, with typical applications, including the measurement of monodisperse particles, sodium fire aerosols, reactor crud particles and cadmium-silver aerosol particles. (U.K.)

  6. Effect of fuel particles' size variations on multiplication factor in pebble-bed nuclear reactor

    International Nuclear Information System (INIS)

    Snoj, L.; Ravnik, M.

    2005-01-01

    The pebble-bed reactor (Pbr) spherical fuel element consists of two radial zones: the inner zone, in which the fissile material in form of the so-called TRISO particles is uniformly dispersed in graphite matrix and the outer zone, a shell of pure graphite. A TRISO particle is composed of a fissile kernel (UO 2 ) and several layers of carbon composites. The effect of TRISO particles' size variations and distance between them on PBR multiplication factor is studied using MCNP code. Fuel element is modelled in approximation of a cubical unit cell with periodic boundary condition. The multiplication factor of the fuel element depends on the size of the TRISO particles due to resonance self-shielding effect and on the inter-particle distance due to inter-kernel shadowing. (author)

  7. Simulation study of effects of initial particle size distribution on dissolution

    International Nuclear Information System (INIS)

    Wang, G.; Xu, D.S.; Ma, N.; Zhou, N.; Payton, E.J.; Yang, R.; Mills, M.J.; Wang, Y.

    2009-01-01

    Dissolution kinetics of γ' particles in binary Ni-Al alloys with different initial particle size distributions (PSD) is studied using a three-dimensional (3D) quantitative phase field model. By linking model inputs directly to thermodynamic and atomic mobility databases, microstructural evolution during dissolution is simulated in real time and length scales. The model is first validated against analytical solution for dissolution of a single γ' particle in 1D and numerical solution in 3D before it is applied to investigate the effects of initial PSD on dissolution kinetics. Four different types of PSD, uniform, normal, log-normal and bimodal, are considered. The simulation results show that the volume fraction of γ' particles decreases exponentially with time, while the temporal evolution of average particle size depends strongly on the initial PSD

  8. In-situ detection of micron-sized dust particles in near-Earth space

    Science.gov (United States)

    Gruen, E.; Zook, H. A.

    1985-01-01

    In situ detectors for micron sized dust particles based on the measurement of impact ionization have been flown on several space missions (Pioneer 8/9, HEOS-2 and Helios 1/2). Previous measurements of small dust particles in near-Earth space are reviewed. An instrument is proposed for the measurement of micron sized meteoroids and space debris such as solid rocket exhaust particles from on board an Earth orbiting satellite. The instrument will measure the mass, speed, flight direction and electrical charge of individually impacting debris and meteoritic particles. It is a multicoincidence detector of 1000 sq cm sensitive area and measures particle masses in the range from 10 to the -14th power g to 10 to the -8th power g at an impact speed of 10 km/s. The instrument is lightweight (5 kg), consumes little power (4 watts), and requires a data sampling rate of about 100 bits per second.

  9. Application of ferrofluid density separation to particles in the micrometer-size range

    International Nuclear Information System (INIS)

    Strebin, R.S. Jr.; Johnson, J.W.; Robertson, D.M.

    1976-02-01

    A device designed and described by AVCO* as a ''Ferrofluid Density Separator''/sup (1)/ develops an apparent fluid density from nominally 2 to 20 g/cm 3 dependent on the magnitude of an imposed magnetic field gradient. The ferrofluid retains other normal properties of a liquid. One of these devices and a concentration series of ferrofluids were obtained in order to determine the practicality of separating groups of micrometer-size particles into density fractions. Such separations would be of enormous value in the study of various particle burdens because particles of interest are almost always diluted with overwhelming amounts of other particles. The results of a study of separations of micrometer-size particles with the ferrofluid density separator are presented

  10. Size controlled hydroxyapatite and calcium carbonate particles: synthesis and their application as templates for SERS platform.

    Science.gov (United States)

    Parakhonskiy, B V; Svenskaya, Yu I; Yashchenok, A М; Fattah, H A; Inozemtseva, O A; Tessarolo, F; Antolini, R; Gorin, D A

    2014-06-01

    An elegant route for hydroxyapatite (HA) particle synthesis via ionic exchange reaction is reported. Calcium carbonate particles (CaCO3) were recrystallized into HA beads in water solution with phosphate ions. The size of initial CaCO3 particles was controlled upon the synthesis by varying the amount of ethylene glycol (EG) in aqueous solution. The average size of HA beads ranged from 0.6±0.1 to 4.3±1.1μm. Silver nanoparticles were deposited on the surface of HA and CaCO3 particles via silver mirror reaction. Surface enhanced Raman scattering of silver functionalized beads was demonstrated by detecting Rhodamine B. CaCO3 and HA particles have a great potential for design of carrier which can provide diagnostic and therapeutic functions. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. 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

    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...

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

    Czech Academy of Sciences Publication Activity Database

    Pacáková, Barbara; Mantlíková, Alice; Nižňanský, D.; Kubíčková, Simona; Vejpravová, Jana

    2016-01-01

    Roč. 28, č. 20 (2016), 1-11, č. článku 206004. ISSN 0953-8984 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:68378271 Keywords : magnetic nanoparticles * single-particle anisotropy * dipolar energy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.649, year: 2016

  13. Stable Carbon Fractionation In Size Segregated Aerosol Particles Produced By Controlled Biomass Burning

    Science.gov (United States)

    Masalaite, Agne; Garbaras, Andrius; Garbariene, Inga; Ceburnis, Darius; Martuzevicius, Dainius; Puida, Egidijus; Kvietkus, Kestutis; Remeikis, Vidmantas

    2014-05-01

    Biomass burning is the largest source of primary fine fraction carbonaceous particles and the second largest source of trace gases in the global atmosphere with a strong effect not only on the regional scale but also in areas distant from the source . Many studies have often assumed no significant carbon isotope fractionation occurring between black carbon and the original vegetation during combustion. However, other studies suggested that stable carbon isotope ratios of char or BC may not reliably reflect carbon isotopic signatures of the source vegetation. Overall, the apparently conflicting results throughout the literature regarding the observed fractionation suggest that combustion conditions may be responsible for the observed effects. The purpose of the present study was to gather more quantitative information on carbonaceous aerosols produced in controlled biomass burning, thereby having a potential impact on interpreting ambient atmospheric observations. Seven different biomass fuel types were burned under controlled conditions to determine the effect of the biomass type on the emitted particulate matter mass and stable carbon isotope composition of bulk and size segregated particles. Size segregated aerosol particles were collected using the total suspended particle (TSP) sampler and a micro-orifice uniform deposit impactor (MOUDI). The results demonstrated that particle emissions were dominated by the submicron particles in all biomass types. However, significant differences in emissions of submicron particles and their dominant sizes were found between different biomass fuels. The largest negative fractionation was obtained for the wood pellet fuel type while the largest positive isotopic fractionation was observed during the buckwheat shells combustion. The carbon isotope composition of MOUDI samples compared very well with isotope composition of TSP samples indicating consistency of the results. The measurements of the stable carbon isotope ratio in

  14. Polycyclic aromatic hydrocarbons in urban atmosphere of Guangzhou, China: Size distribution characteristics and size-resolved gas-particle partitioning

    Science.gov (United States)

    Yu, Huan; Yu, Jian Zhen

    2012-07-01

    Size distributions of thirteen polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), and organic carbon (OC) in the range of 0.01-18 μm were measured using a nano Micro-Orifice Uniform Deposit Impactor (nano-MOUDI) in an urban location in Guangzhou, China in July 2006. PAH size distributions were fit with five modes and the respective mass median aerodynamic diameters (MMAD) are: Aitken mode (MMAD: ˜0.05 μm), three accumulation modes AMI, AMII, AMIII (MMAD: 0.13-0.17 μm, 0.4-0.45 μm, and 0.9-1.2 μm, respectively), and coarse mode (MMAD: 4-6 μm). Seven-ring PAH was mainly in AMII and AMIII. Five- and six-ring PAHs were found to be abundant in all the three AM. Three- and four-ring PAHs had a significant presence in the coarse mode in addition to the three AM. Size-resolved gas-particle partition coefficients of PAHs (Kp) were estimated using measured EC and OC data. The Kp values of a given PAH could differ by a factor of up to ˜7 on particles in different size modes, with the highest Kp associated with the AMI particles and the lowest Kp associated with the coarse mode particles. Comparison of calculated overall Kp with measured Kp values in Guangzhou by Yang et al. (2010) shows that adsorption on EC appeared to be the dominant mechanism driving the gas-particle partitioning of three- and four-ring PAHs while absorption in OM played a dominant role for five- and six-ring PAHs. The calculated equilibrium timescales of repartitioning indicate that five- to seven-ring PAHs could not achieve equilibrium partitioning within their typical residence time in urban atmospheres, while three- and four-ring PAHs could readily reach new equilibrium states in particles of all sizes. A partitioning flux is therefore proposed to replace the equilibrium assumption in modeling PAH transport and fate.

  15. Particle number size distributions in urban air before and after volatilisation

    Directory of Open Access Journals (Sweden)

    W. Birmili

    2010-05-01

    Full Text Available Aerosol particle number size distributions (size range 0.003–10 μm in the urban atmosphere of Augsburg (Germany were examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration between November 2004 and November 2006 was 12 200 cm−3, i.e. similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer as consequence of more frequent inversion situations and enhanced particulate emissions. The diurnal variations of particle number were shaped by a remarkable maximum in the morning during the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening concentration maximum could frequently be observed, suggesting a re-stratification of the urban atmosphere. Overall, the mixed layer height turned out to be the most influential meteorological parameter on the particle size distribution. Its influence was even greater than that of the geographical origin of the prevailing synoptic-scale air mass.

    Size distributions below 0.8 μm were also measured downstream of a thermodenuder (temperature: 300 °C, allowing to retrieve the volume concentration of non-volatile compounds. The balance of particle number upstream and downstream of the thermodenuder suggests that practically all particles >12 nm contain a non-volatile core while additional nucleation of particles smaller than 6 nm could be observed after the thermodenuder as an interfering artifact of the method. The good correlation between the non-volatile volume concentration and an independent measurement of the aerosol absorption coefficient (R2=0.9 suggests a close correspondence of the refractory and light-absorbing particle fractions. Using the "summation method", an average diameter ratio of particles before and after volatilisation could

  16. Synthesis and electrochemical properties of different sizes of the CuO particles

    International Nuclear Information System (INIS)

    Zhang Xiaojun; Zhang Dongen; Ni Xiaomin; Song Jimei; Zheng Huagui

    2008-01-01

    Well-dispersed cupric oxide (CuO) nanoparticles with the size from 10 to 100 nm were successfully synthesized by thermal decomposition of CuC 2 O 4 precursor at 400 deg. C. The prepared CuO nanoparticles of different sizes used as anode materials for Li ion battery all exhibit high electrochemical capacity at the first discharge. However, with the particles size changing, an interesting phenomenon appears. That is, the larger size of the particles is, the discharge capacity of the first time smaller is, while that of the second time is larger. At the same time, the mechanism of the above phenomenon is discussed in this paper. Surprisingly, we have synthesized the copper nanoparticles with different sizes by the CuO of different sizes as the electrodes

  17. Effect on blood lead of airborne lead particles characterized by size.

    Science.gov (United States)

    Park, Dong-Uk; Paik, Nam-Won

    2002-03-01

    Worker exposure to airborne lead particles was evaluated for a total of 117 workers in 12 work-places of four different industrial types in Korea. The particle sizes were measured using 8-stage cascade impactors worn by the workers. Mass median aerodynamic diameters (MMAD) were determined by type of industry and percentage of lead particles as a fraction of airborne lead (PbA) concentration was determined by particle size. Blood lead (PbB) levels of workers who matched airborne lead samples were also examined. A Scheffé's pairwise comparison test showed that MMAD and the fractions of each of respirable particles and lead particles lead particles lead particles (r = 0.82) than that between concentrations of small particles and PbA (r = 0.61). A simple linear regression indicated that PbB correlated better with respirable lead concentration (r2 = 0.35, P = 0.0001) than with PbA concentration and had a higher slope coefficient. Controlling for respirable lead concentration reduced the partial correlation coefficient between PbA concentration and PbB level from 0.56 to 0.20 (P = 0.053). The results indicate that the contribution of respirable lead particles to lead absorption would be greater than that of PbA. This study concludes that the measurement of PbA only may not properly reflect a worker's exposure to lead particles with diverse characteristics. For the evaluation of a worker's exposure to various types of lead particles, it is recommended that respirable lead particles as well as PbA be measured.

  18. Sources and mixing state of size-resolved elemental carbon particles in a European megacity: Paris

    Science.gov (United States)

    Healy, R. M.; Sciare, J.; Poulain, L.; Kamili, K.; Merkel, M.; Müller, T.; Wiedensohler, A.; Eckhardt, S.; Stohl, A.; Sarda-Estève, R.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J. C.

    2012-02-01

    An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed to investigate the size-resolved chemical composition of single particles at an urban background site in Paris, France, as part of the MEGAPOLI winter campaign in January/February 2010. ATOFMS particle counts were scaled to match coincident Twin Differential Mobility Particle Sizer (TDMPS) data in order to generate hourly size-resolved mass concentrations for the single particle classes observed. The total scaled ATOFMS particle mass concentration in the size range 150-1067 nm was found to agree very well with the sum of concurrent High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and Multi-Angle Absorption Photometer (MAAP) mass concentration measurements of organic carbon (OC), inorganic ions and black carbon (BC) (R2 = 0.91). Clustering analysis of the ATOFMS single particle mass spectra allowed the separation of elemental carbon (EC) particles into four classes: (i) EC attributed to biomass burning (ECbiomass), (ii) EC attributed to traffic (ECtraffic), (iii) EC internally mixed with OC and ammonium sulfate (ECOCSOx), and (iv) EC internally mixed with OC and ammonium nitrate (ECOCNOx). Average hourly mass concentrations for EC-containing particles detected by the ATOFMS were found to agree reasonably well with semi-continuous quantitative thermal/optical EC and optical BC measurements (r2 = 0.61 and 0.65-0.68 respectively, n = 552). The EC particle mass assigned to fossil fuel and biomass burning sources also agreed reasonably well with BC mass fractions assigned to the same sources using seven-wavelength aethalometer data (r2 = 0.60 and 0.48, respectively, n = 568). Agreement between the ATOFMS and other instrumentation improved noticeably when a period influenced by significantly aged, internally mixed EC particles was removed from the intercomparison. 88% and 12% of EC particle mass was apportioned to fossil fuel and biomass burning respectively using the ATOFMS data

  19. Sources and mixing state of size-resolved elemental carbon particles in a European megacity: Paris

    Directory of Open Access Journals (Sweden)

    R. M. Healy

    2012-02-01

    Full Text Available An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS was deployed to investigate the size-resolved chemical composition of single particles at an urban background site in Paris, France, as part of the MEGAPOLI winter campaign in January/February 2010. ATOFMS particle counts were scaled to match coincident Twin Differential Mobility Particle Sizer (TDMPS data in order to generate hourly size-resolved mass concentrations for the single particle classes observed. The total scaled ATOFMS particle mass concentration in the size range 150–1067 nm was found to agree very well with the sum of concurrent High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS and Multi-Angle Absorption Photometer (MAAP mass concentration measurements of organic carbon (OC, inorganic ions and black carbon (BC (R2 = 0.91. Clustering analysis of the ATOFMS single particle mass spectra allowed the separation of elemental carbon (EC particles into four classes: (i EC attributed to biomass burning (ECbiomass, (ii EC attributed to traffic (ECtraffic, (iii EC internally mixed with OC and ammonium sulfate (ECOCSOx, and (iv EC internally mixed with OC and ammonium nitrate (ECOCNOx. Average hourly mass concentrations for EC-containing particles detected by the ATOFMS were found to agree reasonably well with semi-continuous quantitative thermal/optical EC and optical BC measurements (r2 = 0.61 and 0.65–0.68 respectively, n = 552. The EC particle mass assigned to fossil fuel and biomass burning sources also agreed reasonably well with BC mass fractions assigned to the same sources using seven-wavelength aethalometer data (r2 = 0.60 and 0.48, respectively, n = 568. Agreement between the ATOFMS and other instrumentation improved noticeably when a period influenced by significantly aged, internally mixed EC particles was removed from the intercomparison. 88% and 12% of EC particle

  20. The Effect of Particle Size of Wollastonite Filler on Thermal Performance of Intumescent Fire Retardant Coating

    Directory of Open Access Journals (Sweden)

    Zia-ul-Mustafa M.

    2014-07-01

    Full Text Available Intumescent Fire retardant coatings (IFRC’s are one of the simplest ways to protect substrates exposed to fire. In this study, Wollastonite (W filler of two different particle sizes were used to determine the fire performance of intumescent fire retardant coating. The basic ingredients of the coating were ammonium poly-phosphate (APP as acid source, expandable graphite (EG as carbon source, melamine (MEL as blowing agent in epoxy binder, boric acid as additive and hardener as curing agent. A series of coating formulations were developed by using different weight percentages of both sized Wollastonite fillers. The coated steel substrate samples were tested for fire performance using Bunsen burner and char expansion was measured using furnace fire test. A Comparison of the coatings thermal performance was determined. Wollastonite containing filler particle size 10 μm showed better thermal performance than formulations containing filler’s particle size 44 μm.

  1. Mean size among the particles of short-lived radon daughter products in the atmosphere

    International Nuclear Information System (INIS)

    Nakatani, S.

    1980-01-01

    The diffusion-battery method is used to classify the radioactive particles according to their sizes. The diffusion coefficient is determined from the fractional penetration of the particles through the battery. Particle radii are derived from the diffusion coefficients with the Stokes-Cunningham-Millikan formula. At the exit and entrance of the battery, individual concentrations of radon daughter products 218 Po, 214 Pb, 214 Bi are determined. Thus the mean sizes of individual radon daughters can be obtained from the fractional penetration of individual nuclides through the diffusion battery. Despite large statistical fluctuations the mean size of 214 Bi is always shifted toward the larger size region as compared with those of other radionuclides

  2. Analysis of tecniques for measurement of the size distribution of solid particles

    Directory of Open Access Journals (Sweden)

    F. O. Arouca

    2005-03-01

    Full Text Available Determination of the size distribution of solid particles is fundamental for analysis of the performance several pieces of equipment used for solid-fluid separation. The main objective of this work is to compare the results obtained with two traditional methods for determination of the size grade distribution of powdery solids: the gamma-ray attenuation technique (GRAT and the LADEQ test tube technique. The effect of draining the suspension in the two techniques used was also analyzed. The GRAT can supply the particle size distribution of solids through the monitoring of solid concentration in experiments on batch settling of diluted suspensions. The results show that use of the peristaltic pump in the GRAT and the LADEQ methods produced a significant difference between the values obtained for the parameters of the particle size model.

  3. The necessity of microscopy to characterize the optical properties of size-selected, nonspherical aerosol particles.

    Science.gov (United States)

    Veghte, Daniel P; Freedman, Miriam A

    2012-11-06

    It is currently unknown whether mineral dust causes a net warming or cooling effect on the climate system. This uncertainty stems from the varied and evolving shape and composition of mineral dust, which leads to diverse interactions of dust with solar and terrestrial radiation. To investigate these interactions, we have used a cavity ring-down spectrometer to study the optical properties of size-selected calcium carbonate particles, a reactive component of mineral dust. The size selection of nonspherical particles like mineral dust can differ from spherical particles in the polydispersity of the population selected. To calculate the expected extinction cross sections, we use Mie scattering theory for monodisperse spherical particles and for spherical particles with the polydispersity observed in transmission electron microscopy images. Our results for calcium carbonate are compared to the well-studied system of ammonium sulfate. While ammonium sulfate extinction cross sections agree with Mie scattering theory for monodisperse spherical particles, the results for calcium carbonate deviate at large and small particle sizes. We find good agreement for both systems, however, between the calculations performed using the particle images and the cavity ring-down data, indicating that both ammonium sulfate and calcium carbonate can be treated as polydisperse spherical particles. Our results indicate that having an independent measure of polydispersity is essential for understanding the optical properties of nonspherical particles measured with cavity ring-down spectroscopy. Our combined spectroscopy and microscopy techniques demonstrate a novel method by which cavity ring-down spectroscopy can be extended for the study of more complex aerosol particles.

  4. Air bubble-induced detachment of polystyrene particles with different sizes from collector surfaces in a parallel plate flow chamber

    NARCIS (Netherlands)

    Gomez-Suarez, C; van der Mei, HC; Busscher, HJ

    2001-01-01

    Particle size was found to be an important factor in air bubble-induced detachment of colloidal particles from collector surfaces in a parallel plate flow chamber and generally polystyrene particles with a diameter of 806 nm detached less than particles with a diameter of 1400 nm. Particle

  5. Distinguishing magnetic particle size of iron oxide nanoparticles with first-order reversal curves

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, Monika; Hirt, Ann M., E-mail: ann.hirt@erdw.ethz.ch [Department of Earth Sciences, Institute of Geophysics, ETH-Zurich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland); Widdrat, Marc; Faivre, Damien [Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, D-14424 Potsdam (Germany); Tompa, Éva; Pósfai, Mihály [Department of Earth and Environmental Sciences, University of Pannonia, Egyetem u. 10, H-8200 Veszprém (Hungary); Uebe, Rene; Schüler, Dirk [Department Biologie I, LMU Munich, Großhaderner Str. 2, D-82152 Martinsried (Germany)

    2014-09-28

    Magnetic nanoparticles encompass a wide range of scientific study and technological applications. The success of using the nanoparticles in various applications demands control over size, dispersibility, and magnetics. Hence, the nanoparticles are often characterized by transmission electron microscopy (TEM), X-ray diffraction, and magnetic hysteresis loops. TEM analysis requires a thin layer of dispersed particles on the grid, which may often lead to particle aggregation thus making size analysis difficult. Magnetic hysteresis loops on the other hand provide information on the bulk property of the material without discriminating size, composition, and interaction effects. First order reversal curves (FORCs), described as an assembly of partial hysteresis loops originating from the major loop are efficient in identifying the domain size, composition, and interaction in a magnetic system. This study presents FORC diagrams on a variety of well-characterized biogenic and synthetic magnetite nanoparticles. It also introduces deconvoluted reversible and irreversible components from FORC as an important method for obtaining a semi-quantitative measure of the effective magnetic particle size. This is particularly important in a system with aggregation and interaction among the particles that often leads to either the differences between physical size and effective magnetic size. We also emphasize the extraction of secondary components by masking dominant coercivity fraction on FORC diagram to explore more detailed characterization of nanoparticle systems.

  6. Effect of Particle Size on Electrode Potential and Thermodynamics of Nanoparticles Electrode in Theory and Experiment

    International Nuclear Information System (INIS)

    Yunfeng, Yang; Yongqiang, Xue; Zixiang, Cui; Miaozhi, Zhao

    2014-01-01

    The particle size of electrode materials has a significant influence on the standard electrode potential and the thermodynamic properties of electrode reactions. In this paper, the size-dependent electrochemical thermodynamics has been theoretically investigated and successfully deduced electrochemical thermodynamics equations for nanoparticles electrode. At the same time, the electrode potential and thermodynamical properties of Ag 2 O/Ag nanoparticles electrode constructed by the solid and spherical Ag 2 O nanoparticles with different sizes further testified that the particle size of nanoparticles has a significant effect on electrochemical thermodynamics. The results show that the electrode potential depends on that of the smallest nanoparticle in a nanoparticles electrode which consisted of different particle sizes of nano-Ag 2 O. When the size of Ag 2 O nanoparticles reduces, the standard electrode potentials and the equilibrium constants of the corresponding electrode reactions increase, and the temperature coefficient, the mole Gibbs energy change, the mole enthalpy change and the mole entropy change decrease. Moreover, these physical quantities are all linearly related with the reciprocal of average particle size (r > 10 nm). The experimental regularities coincide with the theoretical equations

  7. Distinguishing magnetic particle size of iron oxide nanoparticles with first-order reversal curves

    International Nuclear Information System (INIS)

    Kumari, Monika; Hirt, Ann M.; Widdrat, Marc; Faivre, Damien; Tompa, Éva; Pósfai, Mihály; Uebe, Rene; Schüler, Dirk

    2014-01-01

    Magnetic nanoparticles encompass a wide range of scientific study and technological applications. The success of using the nanoparticles in various applications demands control over size, dispersibility, and magnetics. Hence, the nanoparticles are often characterized by transmission electron microscopy (TEM), X-ray diffraction, and magnetic hysteresis loops. TEM analysis requires a thin layer of dispersed particles on the grid, which may often lead to particle aggregation thus making size analysis difficult. Magnetic hysteresis loops on the other hand provide information on the bulk property of the material without discriminating size, composition, and interaction effects. First order reversal curves (FORCs), described as an assembly of partial hysteresis loops originating from the major loop are efficient in identifying the domain size, composition, and interaction in a magnetic system. This study presents FORC diagrams on a variety of well-characterized biogenic and synthetic magnetite nanoparticles. It also introduces deconvoluted reversible and irreversible components from FORC as an important method for obtaining a semi-quantitative measure of the effective magnetic particle size. This is particularly important in a system with aggregation and interaction among the particles that often leads to either the differences between physical size and effective magnetic size. We also emphasize the extraction of secondary components by masking dominant coercivity fraction on FORC diagram to explore more detailed characterization of nanoparticle systems.

  8. Raman spectroscopic identification of size-selected airborne particles for quantitative exposure assessment

    International Nuclear Information System (INIS)

    Steer, Brian; Gorbunov, Boris; Price, Mark C; Podoleanu, Adrian

    2016-01-01

    In this paper we present a method for the quantification of chemically distinguished airborne particulate matter, required for health risk assessment. Rather than simply detecting chemical compounds in a sample, we demonstrate an approach for the quantification of exposure to airborne particles and nanomaterials. In line with increasing concerns over the proliferation of engineered particles we consider detection of synthetically produced ZnO crystals. A multi-stage approach is presented whereby the particles are first aerodynamically size segregated from a lab-generated single component aerosol in an impaction sampler. These size fractionated samples are subsequently analysed by Raman spectroscopy. Imaging analysis is applied to Raman spatial maps to provide chemically specific quantification of airborne exposure against background which is critical for health risk evaluation of exposure to airborne particles. Here we present a first proof-of-concept study of the methodology utilising particles in the 2–4 μm aerodynamic diameter range to allow for validation of the approach by comparison to optical microscopy. The results show that the combination of these techniques provides independent size and chemical discrimination of particles. Thereby a method is provided to allow quantitative and chemically distinguished measurements of aerosol concentrations separated into exposure relevant size fractions. (paper)

  9. A novel method for determination of particle size distribution in-process

    Science.gov (United States)

    Salaoru, Tiberiu A.; Li, Mingzhong; Wilkinson, Derek

    2009-07-01

    The pharmaceutical and fine chemicals industries are strongly concerned with the manufacture of high value-added speciality products, often in solid form. On-line measurement of solid particle size is vital for reliable control of product properties. The established techniques, such as laser diffraction or spectral extinction, require dilution of the process suspension when measuring from typical manufacturing streams because of their high concentration. Dilution to facilitate measurement can result in changes of both size and form of particles, especially during production processes such as crystallisation. In spectral extinction, the degree of light scattering and absorption by a suspension is measured. However, for concentrated suspensions the interpretation of light extinction measurements is difficult because of multiple scattering and inter-particle interaction effects and at higher concentrations extinction is essentially total so the technique can no longer be applied. At the same time, scattering by a dispersion also causes a change of phase which affects the real component of the suspension's effective refractive index which is a function of particle size and particle and dispersant refractive indices. In this work, a novel prototype instrument has been developed to measure particle size distribution in concentrated suspensions in-process by measuring suspension refractive index at incidence angles near the onset of total internal reflection. Using this technique, the light beam does not pass through the suspension being measured so suspension turbidity does not impair the measurement.

  10. Soot Particle Size Distribution Functions in a Turbulent Non-Premixed Ethylene-Nitrogen Flame

    KAUST Repository

    Boyette, Wesley

    2017-02-21

    A scanning mobility particle sizer with a nano differential mobility analyzer was used to measure nanoparticle size distribution functions in a turbulent non-premixed flame. The burner utilizes a premixed pilot flame which anchors a C2H4/N2 (35/65) central jet with ReD = 20,000. Nanoparticles in the flame were sampled through a N2-filled tube with a 500- μm orifice. Previous studies have shown that insufficient dilution of the nanoparticles can lead to coagulation in the sampling line and skewed particle size distribution functions. A system of mass flow controllers and valves were used to vary the dilution ratio. Single-stage and two-stage dilution systems were investigated. A parametric study on the effect of the dilution ratio on the observed particle size distribution function indicates that particle coagulation in the sampling line can be eliminated using a two-stage dilution process. Carbonaceous nanoparticle (soot) concentration particle size distribution functions along the flame centerline at multiple heights in the flame are presented. The resulting distributions reveal a pattern of increasing mean particle diameters as the distance from the nozzle along the centerline increases.

  11. Combustion synthesis of micron-sized Sm2Co17 particles via mechanochemical processing

    International Nuclear Information System (INIS)

    Liu, W.; McCormick, P.G.

    1998-01-01

    Full text: The spontaneous formation of Sm 2 Co 17 micron-sized particles via a mechanically induced combustion reaction has been investigated. Sm 2 Co 17 alloy particles of 0.1--2 μm in size embedded in a CaO matrix formed directly via a combustion reaction induced by milling the powder mixture of Sm 2 O 3 , CoO, CaO and Ca over a critical time. The micron-sized Sm 2 Co 17 particles were found to have the TbCu 7 -type structure and characterized by a coercivity value of 7.8 kOe while embedded in the CaO matrix. The effect of subsequent heat treatment on the structure and magnetic properties of as-milled samples was also investigated. Removal of the CaO by a carefully controlled washing process yielded micron-sized Sm 2 Co 17 particles without significant oxidation of the particles. These fine Sm 2 Co 17 particles can be used to produce anisotropic bulk or bonded magnets

  12. Soot Particle Size Distribution Functions in a Turbulent Non-Premixed Ethylene-Nitrogen Flame

    KAUST Repository

    Boyette, Wesley; Chowdhury, Snehaunshu; Roberts, William L.

    2017-01-01

    A scanning mobility particle sizer with a nano differential mobility analyzer was used to measure nanoparticle size distribution functions in a turbulent non-premixed flame. The burner utilizes a premixed pilot flame which anchors a C2H4/N2 (35/65) central jet with ReD = 20,000. Nanoparticles in the flame were sampled through a N2-filled tube with a 500- μm orifice. Previous studies have shown that insufficient dilution of the nanoparticles can lead to coagulation in the sampling line and skewed particle size distribution functions. A system of mass flow controllers and valves were used to vary the dilution ratio. Single-stage and two-stage dilution systems were investigated. A parametric study on the effect of the dilution ratio on the observed particle size distribution function indicates that particle coagulation in the sampling line can be eliminated using a two-stage dilution process. Carbonaceous nanoparticle (soot) concentration particle size distribution functions along the flame centerline at multiple heights in the flame are presented. The resulting distributions reveal a pattern of increasing mean particle diameters as the distance from the nozzle along the centerline increases.

  13. New insights into the oleate flotation response of feldspar particles of different sizes: Anisotropic adsorption model.

    Science.gov (United States)

    Xu, Longhua; Tian, Jia; Wu, Houqin; Deng, Wei; Yang, Yaohui; Sun, Wei; Gao, Zhiyong; Hu, Yuehua

    2017-11-01

    The anisotropic adsorption of sodium oleate (NaOL) on feldspar surfaces was investigated to elucidate the different flotation properties of feldspar particles of four different size ranges. Microflotation experiments showed that the feldspar flotation recovery of particles with sizes spanning different ranges decreased in the order 0-19>19-38>45-75>38-45μm. Zeta potential and FTIR measurements showed that NaOL was chemically adsorbed on the Al sites of the feldspar surface. The anisotropic surface energies and broken bond densities estimated by density functional theory calculations showed that, although feldspar mostly exposed (010) and (001) surfaces, only the (001) surfaces contained the Al sites needed for NaOL adsorption. The interaction energies calculated by molecular dynamics simulations confirmed the more favorable NaOL adsorption on (001) than (010) surfaces, which may represent the main cause for the anisotropic NaOL adsorption on feldspar particles of different sizes. SEM measurements showed that the main exposed surfaces on coarse and fine feldspar particles were the side (010) and basal (001) ones, respectively. A higher fraction of Al-rich (001) surfaces is exposed on fine feldspar particles, resulting in better floatability compared with coarse particles. XPS and adsorption measurements confirmed that the Al content on the feldspar surface varied with the particle size, explaining the different NaOL flotation of feldspar particles of different sizes. Therefore, the present results suggest that coarsely ground ore should be used for the separation of feldspar gangue minerals. Further improvements in the flotation separation of feldspar from associated valuable minerals can be achieved through selective comminution or grinding processes favoring the exposure of (010) surfaces. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Temperature and particle-size dependent viscosity data for water-based nanofluids - Hysteresis phenomenon

    International Nuclear Information System (INIS)

    Nguyen, C.T.; Desgranges, F.; Roy, G.; Galanis, N.; Mare, T.; Boucher, S.; Angue Mintsa, H.

    2007-01-01

    In the present paper, we have investigated experimentally the influence of both the temperature and the particle size on the dynamic viscosities of two particular water-based nanofluids, namely water-Al 2 O 3 and water-CuO mixtures. The measurement of nanofluid dynamic viscosities was accomplished using a 'piston-type' calibrated viscometer based on the Couette flow inside a cylindrical measurement chamber. Data were collected for temperatures ranging from ambient to 75 deg. C, for water-Al 2 O 3 mixtures with two different particle diameters, 36 nm and 47 nm, as well as for water-CuO nanofluid with 29 nm particle size. The results show that for particle volume fractions lower than 4%, viscosities corresponding to 36 nm and 47 nm particle-size alumina-water nanofluids are approximately identical. For higher particle fractions, viscosities of 47 nm particle-size are clearly higher than those of 36 nm size. Viscosities corresponding to water-oxide copper are the highest among the nanofluids tested. The temperature effect has been investigated thoroughly. A more complete viscosity data base is presented for the three nanofluids considered, with several experimental correlations proposed for low particle volume fractions. It has been found that the application of Einstein's formula and those derived from the linear fluid theory seems not to be appropriate for nanofluids. The hysteresis phenomenon on viscosity measurement, which is believed to be the first observed for nanofluids, has raised serious concerns regarding the use of nanofluids for heat transfer enhancement purposes

  15. Size-sensitive particle trajectories in three-dimensional micro-bubble acoustic streaming flows

    Science.gov (United States)

    Volk, Andreas; Rossi, Massimiliano; Hilgenfeldt, Sascha; Rallabandi, Bhargav; Kähler, Christian; Marin, Alvaro

    2015-11-01

    Oscillating microbubbles generate steady streaming flows with interesting features and promising applications for microparticle manipulation. The flow around oscillating semi-cylindrical bubbles has been typically assumed to be independent of the axial coordinate. However, it has been recently revealed that particle motion is strongly three-dimensional: Small tracer particles follow vortical trajectories with pronounced axial displacements near the bubble, weaving a toroidal stream-surface. A well-known consequence of bubble streaming flows is size-dependent particle migration, which can be exploited for sorting and trapping of microparticles in microfluidic devices. In this talk, we will show how the three-dimensional toroidal topology found for small tracer particles is modified as the particle size increases up to 1/3 of the bubble radius. Our results show size-sensitive particle positioning along the axis of the semi-cylindrical bubble. In order to analyze the three-dimensional sorting and trapping capabilities of the system, experiments with an imposed flow and polydisperse particle solutions are also shown.

  16. Size-based sorting of micro-particles using microbubble streaming

    Science.gov (United States)

    Wang, Cheng; Jalikop, Shreyas; Hilgenfeldt, Sascha

    2009-11-01

    Oscillating microbubbles driven by ultrasound have shown great potential in microfluidic applications, such as transporting particles and promoting mixing [1-3]. The oscillations generate secondary steady streaming that can also trap particles. We use the streaming to develop a method of sorting particles of different sizes in an initially well-mixed solution. The solution is fed into a channel consisting of bubbles placed periodically along a side wall. When the bubbles are excited by an ultrasound piezo-electric transducer to produce steady streaming, the flow field is altered by the presence of the particles. This effect is dependent on particle size and results in size-based sorting of the particles. The effectiveness of the separation depends on the dimensions of the bubbles and particles as well as on the ultrasound frequency. Our experimental studies are aimed at a better understanding of the design and control of effective microfluidic separating devices. Ref: [1] P. Marmottant and S. Hilgenfeldt, Nature 423, 153 (2003). [2] P. Marmottant and S. Hilgenfeldt, Proc. Natl. Acad. Science USA, 101, 9523 (2004). [3] P. Marmottant, J.-P. Raven, H. Gardeniers, J. G. Bomer, and S. Hilgenfeldt, J. Fluid Mech., vol.568, 109 (2006).

  17. Effect of graphite particle size and content on the formation mechanism of detonation polycrystalline diamond

    Science.gov (United States)

    Tong, Y.; Cao, Y.; Liu, R.; Shang, S. Y.; Huang, F. L.

    2018-03-01

    The formation mechanism of detonation polycrystalline diamond (DPD) generated from the detonation of a mixed RDX/graphite explosive is investigated. It is found experimentally that the DPD conversion rate decreases with both the content and the particle size of the graphite. Moreover, the particle sizes of the generated DPD powder are analyzed, which shows that, with the decrease in the graphite particle size, the mean number diameter of DPD decreases, but the mean volume diameter increases. In addition, with the help of scanning electron microscopy, it is observed that the in situ phase change occurs in the graphite particles, by which the small particles combine to form numerous large DPD particles. Based on both the experimental data and the classical ZND detonation model, we divide such a DPD synthesis process into two stages: In the first stage, the in situ phase change from graphite to diamond is dominant, supplemented by some coalescence growth at high pressure and temperature, which is affected mainly by the detonation performance of the mixed explosive under consideration. In the second stage, the graphitization of DPD caused by the residual heat is dominant, which is affected mainly by the unloading rate of the particle temperature.

  18. Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives

    International Nuclear Information System (INIS)

    Contado, Catia; Ravani, Laura; Passarella, Martina

    2013-01-01

    Graphical abstract: -- Highlights: •Four types of SiO 2 particles were characterized by SdFFF, PCS and EM techniques. •Clusters of 10 nm nanoparticles were found in some SiO 2 samples. •A method was set up to extract SiO 2 particles from food matrices. •The effects of the carrier solution composition on SdFFF separations were evaluated. •Particle size distributions were obtained from SiO 2 particles extracted from foodstuffs. -- Abstract: Four types of SiO 2 , available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w −1 ) a nearly silica-free instant barley coffee powder with a known SiO 2 sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO 2 particles and verify the new particle size distribution. The SiO 2 content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w −1 ). The protocol to isolate the silica particles was so applied to the most SiO 2 -rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification

  19. Size distribution and hygroscopic properties of aerosol particles from dry-season biomass burning in Amazonia

    Directory of Open Access Journals (Sweden)

    J. Rissler

    2006-01-01

    Full Text Available Aerosol particle number size distributions and hygroscopic properties were measured at a pasture site in the southwestern Amazon region (Rondonia. The measurements were performed 11 September-14 November 2002 as part of LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate, and cover the later part of the dry season (with heavy biomass burning, a transition period, and the onset of the wet period. Particle number size distributions were measured with a DMPS (Differential Mobility Particle Sizer, 3-850nm and an APS (Aerodynamic Particle Sizer, extending the distributions up to 3.3 µm in diameter. An H-TDMA (Hygroscopic Tandem Differential Mobility Analyzer measured the hygroscopic diameter growth factors (Gf at 90% relative humidity (RH, for particles with dry diameters (dp between 20-440 nm, and at several occasions RH scans (30-90% RH were performed for 165nm particles. These data provide the most extensive characterization of Amazonian biomass burning aerosol, with respect to particle number size distributions and hygroscopic properties, presented until now. The evolution of the convective boundary layer over the course of the day causes a distinct diel variation in the aerosol physical properties, which was used to get information about the properties of the aerosol at higher altitudes. The number size distributions averaged over the three defined time periods showed three modes; a nucleation mode with geometrical median diameters (GMD of ~12 nm, an Aitken mode (GMD=61-92 nm and an accumulation mode (GMD=128-190 nm. The two larger modes were shifted towards larger GMD with increasing influence from biomass burning. The hygroscopic growth at 90% RH revealed a somewhat external mixture with two groups of particles; here denoted nearly hydrophobic (Gf~1.09 for 100 nm particles and moderately hygroscopic (Gf~1.26. While the hygroscopic growth factors were surprisingly similar over the

  20. Methods for obtaining true particle size distributions from cross section measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lord, Kristina Alyse [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    Sectioning methods are frequently used to measure grain sizes in materials. These methods do not provide accurate grain sizes for two reasons. First, the sizes of features observed on random sections are always smaller than the true sizes of solid spherical shaped objects, as noted by Wicksell [1]. This is the case because the section very rarely passes through the center of solid spherical shaped objects randomly dispersed throughout a material. The sizes of features observed on random sections are inversely related to the distance of the center of the solid object from the section [1]. Second, on a plane section through the solid material, larger sized features are more frequently observed than smaller ones due to the larger probability for a section to come into contact with the larger sized portion of the spheres than the smaller sized portion. As a result, it is necessary to find a method that takes into account these reasons for inaccurate particle size measurements, while providing a correction factor for accurately determining true particle size measurements. I present a method for deducing true grain size distributions from those determined from specimen cross sections, either by measurement of equivalent grain diameters or linear intercepts.

  1. Cluster analysis of rural, urban, and curbside atmospheric particle size data.

    Science.gov (United States)

    Beddows, David C S; Dall'Osto, Manuel; Harrison, Roy M

    2009-07-01

    Particle size is a key determinant of the hazard posed by airborne particles. Continuous multivariate particle size data have been collected using aerosol particle size spectrometers sited at four locations within the UK: Harwell (Oxfordshire); Regents Park (London); British Telecom Tower (London); and Marylebone Road (London). These data have been analyzed using k-means cluster analysis, deduced to be the preferred cluster analysis technique, selected from an option of four partitional cluster packages, namelythe following: Fuzzy; k-means; k-median; and Model-Based clustering. Using cluster validation indices k-means clustering was shown to produce clusters with the smallest size, furthest separation, and importantly the highest degree of similarity between the elements within each partition. Using k-means clustering, the complexity of the data set is reduced allowing characterization of the data according to the temporal and spatial trends of the clusters. At Harwell, the rural background measurement site, the cluster analysis showed that the spectra may be differentiated by their modal-diameters and average temporal trends showing either high counts during the day-time or night-time hours. Likewise for the urban sites, the cluster analysis differentiated the spectra into a small number of size distributions according their modal-diameter, the location of the measurement site, and time of day. The responsible aerosol emission, formation, and dynamic processes can be inferred according to the cluster characteristics and correlation to concurrently measured meteorological, gas phase, and particle phase measurements.

  2. Forecast errors in dust vertical distributions over Rome (Italy): Multiple particle size representation and cloud contributions

    Science.gov (United States)

    Kishcha, P.; Alpert, P.; Shtivelman, A.; Krichak, S. O.; Joseph, J. H.; Kallos, G.; Katsafados, P.; Spyrou, C.; Gobbi, G. P.; Barnaba, F.; Nickovic, S.; PéRez, C.; Baldasano, J. M.

    2007-08-01

    In this study, forecast errors in dust vertical distributions were analyzed. This was carried out by using quantitative comparisons between dust vertical profiles retrieved from lidar measurements over Rome, Italy, performed from 2001 to 2003, and those predicted by models. Three models were used: the four-particle-size Dust Regional Atmospheric Model (DREAM), the older one-particle-size version of the SKIRON model from the University of Athens (UOA), and the pre-2006 one-particle-size Tel Aviv University (TAU) model. SKIRON and DREAM are initialized on a daily basis using the dust concentration from the previous forecast cycle, while the TAU model initialization is based on the Total Ozone Mapping Spectrometer aerosol index (TOMS AI). The quantitative comparison shows that (1) the use of four-particle-size bins in the dust modeling instead of only one-particle-size bins improves dust forecasts; (2) cloud presence could contribute to noticeable dust forecast errors in SKIRON and DREAM; and (3) as far as the TAU model is concerned, its forecast errors were mainly caused by technical problems with TOMS measurements from the Earth Probe satellite. As a result, dust forecast errors in the TAU model could be significant even under cloudless conditions. The DREAM versus lidar quantitative comparisons at different altitudes show that the model predictions are more accurate in the middle part of dust layers than in the top and bottom parts of dust layers.

  3. Particle Size Affects Concentration-Dependent Cytotoxicity of Chitosan Nanoparticles towards Mouse Hematopoietic Stem Cells

    International Nuclear Information System (INIS)

    Zaki, S. S. O.; Ibrahim, M. N.; Katas, H.

    2015-01-01

    Chitosan nanoparticles (CSNPs) have been extensively applied in medical and pharmaceutical fields as promising drug delivery systems. Despite that, the safety of CSNPs remains inadequate and needs further investigation, particularly on hematopoietic stem cells (HSCs). CSNPs were prepared by ionic gelation method and later were characterized for their physical characteristics (particle size and zeta potential). Cytotoxicity of CSNPs was assessed by MTT assay. Particle size was highly influenced by chitosan concentration and molecular weight (medium and high molecular weight (MMW and HMW)). Higher chitosan concentration and molecular weight produced larger nanoparticles. Zeta potential of CSNPs was not significantly affected by chitosan concentrations and molecular weights used in the present study. MMW had a better stability than HMW CSNPs as their particle size and zeta potential were not significantly altered after autoclaving. Cytotoxicity of CSNPs was influenced by zeta potential and particle size. On the other hand, chitosan concentration and molecular weight indirectly influenced cytotoxicity by affecting particle size and zeta potential of CSNPs. In conclusion, cytotoxicity of CSNPs was mainly attributed to their physical characteristics and this opens a strategy to ensure the safety of CSNPs applications in stem cell technology.

  4. Particle size distribution of rice flour affecting the starch enzymatic hydrolysis and hydration properties.

    Science.gov (United States)

    de la Hera, Esther; Gomez, Manuel; Rosell, Cristina M

    2013-10-15

    Rice flour is becoming very attractive as raw material, but there is lack of information about the influence of particle size on its functional properties and starch digestibility. This study evaluates the degree of dependence of the rice flour functional properties, mainly derived from starch behavior, with the particle size distribution. Hydration properties of flours and gels and starch enzymatic hydrolysis of individual fractions were assessed. Particle size heterogeneity on rice flour significantly affected functional properties and starch features, at room temperature and also after gelatinization; and the extent of that effect was grain type dependent. Particle size heterogeneity on rice flour induces different pattern in starch enzymatic hydrolysis, with the long grain having slower hydrolysis as indicated the rate constant (k). No correlation between starch digestibility and hydration properties or the protein content was observed. It seems that in intact granules interactions with other grain components must be taken into account. Overall, particle size fractionation of rice flour might be advisable for selecting specific physico-chemical properties. Copyright © 2013. Published by Elsevier Ltd.

  5. Particle size distribution and property of bacteria attached to carbon fines in drinking water treatment

    Directory of Open Access Journals (Sweden)

    Wang Leilei

    2008-06-01

    Full Text Available The quantitative change and size distribution of particles in the effluents from a sand filter and a granular activated carbon (GAC filter in a drinking water treatment plant were investigated. The average total concentration of particles in the sand filter effluent during a filter cycle was 148 particles/mL, 27 of which were larger than 2 µm in size. The concentration in the GAC effluent (561 particles/mL was significantly greater than that in the sand filter effluent. The concentration of particles larger than 2 µm in the GAC filter effluent reached 201 particles/mL, with the amount of particles with sizes between 2 µm and 15 µm increasing. The most probable number (MPN of carbon fines reached 43 unit/L after six hours and fines between 0.45 µm and 8.0 µm accounted for more than 50%. The total concentration of outflowing bacteria in the GAC filter effluent, 350 CFU (colony-forming units/mL, was greater than that in the sand filter effluent, 210 CFU/mL. The desorbed bacteria concentration reached an average of 310 CFU/mg fines. The disinfection efficiency of desorbed bacteria was lower than 40% with 1.5 mg/L of chlorine. The disinfection effect showed that the inactivation rate with 2.0 mg/L of chloramine (90% was higher than that with chlorine (70%. Experimental results indicated that the high particle concentration in raw water and sedimentation effluent led to high levels of outflowing particles in the sand filter effluent. The activated carbon fines in the effluent accounted for a small proportion of the total particle amount, but the existing bacteria attached to carbon fines may influence the drinking water safety. The disinfection efficiency of desorbed bacteria was lower than that of free bacteria with chlorine, and the disinfection effect on bacteria attached to carbon fines with chloramine was better than that with only chlorine.

  6. Airborne particle-bound brominated flame retardants: Levels, size distribution and indoor-outdoor exchange.

    Science.gov (United States)

    Zhu, Yue-Shan; Yang, Wan-Dong; Li, Xiu-Wen; Ni, Hong-Gang; Zeng, Hui

    2018-02-01

    The quality of indoor environments has a significant impact on public health. Usually, an indoor environment is treated as a static box, in which physicochemical reactions of indoor air contaminants are negligible. This results in conservative estimates for primary indoor air pollutant concentrations, while also ignoring secondary pollutants. Thus, understanding the relationship between indoor and outdoor particles and particle-bound pollutants is of great significance. For this reason, we collected simultaneous indoor and outdoor measurements of the size distribution of airborne brominated flame retardant (BFR) congeners. The time-dependent concentrations of indoor particles and particle-bound BFRs were then estimated with the mass balance model, accounting for the outdoor concentration, indoor source strength, infiltration, penetration, deposition and indoor resuspension. Based on qualitative observation, the size distributions of ΣPBDE and ΣHBCD were characterized by bimodal peaks. According to our results, particle-bound BDE209 and γ-HBCD underwent degradation. Regardless of the surface adsorption capability of particles and the physicochemical properties of the target compounds, the concentration of BFRs in particles of different size fractions seemed to be governed by the particle distribution. Based on our estimations, for airborne particles and particle-bound BFRs, a window-open ventilated room only takes a quarter of the time to reach an equilibrium between the concentration of pollutants inside and outside compared to a closed room. Unfortunately, indoor pollutants and outdoor pollutants always exist simultaneously, which poses a window-open-or-closed dilemma to achieve proper ventilation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Effect of particle size of drug on conversion of crystals to an amorphous state in a solid dispersion with crospovidone.

    Science.gov (United States)

    Sugamura, Yuka; Fujii, Makiko; Nakanishi, Sayaka; Suzuki, Ayako; Shibata, Yusuke; Koizumi, Naoya; Watanabe, Yoshiteru

    2011-01-01

    The effect of particle size on amorphization of drugs in a solid dispersion (SD) was investigated for two drugs, indomethacin (IM) and nifedipine (NP). The SD of drugs were prepared in a mixture with crospovidone by a variety of mechanical methods, and their properties investigated by particle sizing, thermal analysis, and powder X-ray diffraction. IM, which had an initial particle size of 1 µm and tends to aggregate, was forced through a sieve to break up the particles. NP, which had a large initial particle size, was jet-milled. In both cases, reduction of the particle size of the drugs enabled transition to an amorphous state below the melting point of the drug. The reduction in particle size is considered to enable increased contact between the crospovidone and drug particles, increasing interactions between the two compounds. © 2011 Pharmaceutical Society of Japan

  8. Particle size distribution of mainstream tobacco and marijuana smoke. Analysis using the electrical aerosol analyzer.

    Science.gov (United States)

    Anderson, P J; Wilson, J D; Hiller, F C

    1989-07-01

    Accurate measurement of cigarette smoke particle size distribution is important for estimation of lung deposition. Most prior investigators have reported a mass median diameter (MMD) in the size range of 0.3 to 0.5 micron, with a small geometric standard deviation (GSD), indicating few ultrafine (less than 0.1 micron) particles. A few studies, however, have suggested the presence of ultrafine particles by reporting a smaller count median diameter (CMD). Part of this disparity may be due tot he inefficiency to previous sizing methods in measuring ultrafine size range, to evaluate size distribution of smoke from standard research cigarettes, commercial filter cigarettes, and from marijuana cigarettes with different delta 9-tetrahydrocannabinol contents. Four 35-cm3, 2-s puffs were generated at 60-s intervals, rapidly diluted, and passed through a charge neutralizer and into a 240-L chamber. Size distribution for six cigarettes of each type was measured, CMD and GSD were determined from a computer-generated log probability plot, and MMD was calculated. The size distribution parameters obtained were similar for all cigarettes tested, with an average CMD of 0.1 micron, a MMD of 0.38 micron, and a GSD of 2.0. The MMD found using the EAA is similar to that previously reported, but the CMD is distinctly smaller and the GSD larger, indicating the presence of many more ultrafine particles. These results may explain the disparity of CMD values found in existing data. Ultrafine particles are of toxicologic importance because their respiratory tract deposition is significantly higher than for particles 0.3 to 0.5 micron and because their large surface area facilitates adsorption and delivery of potentially toxic gases to the lung.

  9. How does dietary particle size affect carnivore gastrointestinal transit: A dog model.

    Science.gov (United States)

    De Cuyper, A; Hesta, M; Tibosch, S; Wanke, C; Clauss, M; Janssens, G P J

    2018-04-01

    The effect of dietary particle size on gastrointestinal transit in carnivores has not been studied and might offer more insight into their digestive physiology. This study evaluated the effect of two dietary particle sizes (fine = 7.8 mm vs. coarse = 13 mm) of chunked day-old chicks on transit parameters in dogs. Six beagle dogs were fed both dietary treatments in a crossover design of 7 days with transit testing on the fifth day. Transit parameters were assessed using two markers, that is a wireless motility capsule (IntelliCap ® ) and titanium oxide (TiO 2 ). Dietary particle size did not affect gastric emptying time (GRT), small bowel transit time (SBTT), colonic transit time (CTT) and total transit time (aTTT) of the capsule (p > .05). There was no effect of dietary particle size on TiO 2 mean retention time (MRT) (p > .05). The time of last TiO 2 excretion (MaxRT) differed (p = .013) between diets, being later for the coarse diet. Both MRT (R = 0.617, p = .032) and MaxRT (R = 0.814; p = .001) were positively correlated to aTTT. The ratio MRT/aTTT tended towards a difference between diets (p = .059) with the coarse diet exceeding fine diet values. Results show that the difference between capsule measurements and TiO 2 is larger for the fine than the coarse diet suggesting that the capsule becomes more accurate when dietary particle size approaches marker size. Dietary particle size might have affected transit parameters but differences are too small to claim major physiological consequences. © 2017 Blackwell Verlag GmbH.

  10. An experimental study of asphaltene particle sizes in n-heptane-toluene mixtures by light scattering

    Directory of Open Access Journals (Sweden)

    Rajagopal K.

    2004-01-01

    Full Text Available The particle size of asphaltene flocculates has been the subject of many recent studies because of its importance in the control of deposition in petroleum production and processing. We measured the size of asphaltene flocculates in toluene and toluene - n-heptane mixtures, using the light-scattering technique. The asphaltenes had been extracted from Brazilian oil from the Campos Basin, according to British Standards Method IP-143/82. The asphaltene concentration in solution ranged between 10-6 g/ml and 10-7 g/ml. Sizes was measured for a period of about 10000 minutes at a constant temperature of 20°C. We found that the average size of the particles remained constant with time and increase with an increase in amount of n-heptane. The correlation obtained for size with concentration will be useful in asphaltene precipitation models.

  11. Spatio-temporal evolution of the dust particle size distribution in dusty argon rf plasmas

    International Nuclear Information System (INIS)

    Killer, Carsten; Mulsow, Matthias; Melzer, André

    2015-01-01

    An imaging Mie scattering technique has been developed to measure the spatially resolved size distribution of dust particles in extended dust clouds. For large dust clouds of micrometre-sized plastic particles confined in an radio frequency (rf) discharge, a segmentation of the dust cloud into populations of different sizes is observed, even though the size differences are very small. The dust size dispersion inside a population is much smaller than the difference between the populations. Furthermore, the dust size is found to be constantly decreasing over time while the particles are confined in an inert argon plasma. The processes responsible for the shrinking of the dust in the plasma have been addressed by mass spectrometry, ex situ microscopy of the dust size, dust resonance measurements, in situ determination of the dust surface temperature and Fourier transform infrared absorption (FT-IR). It is concluded that both a reduction of dust size and its mass density due to outgassing of water and other volatile constituents as well as chemical etching by oxygen impurities are responsible for the observations. (paper)

  12. Characterization of road runoff with regard to seasonal variations, particle size distribution and the correlation of fine particles and pollutants.

    Science.gov (United States)

    Hilliges, R; Endres, M; Tiffert, A; Brenner, E; Marks, T

    2017-03-01

    Urban runoff is known to transport a significant pollutant load consisting of e.g. heavy metals, salts and hydrocarbons. Interactions between solid and dissolved compounds, proper understanding of particle size distribution, dissolved pollutant fractions and seasonal variations is crucial for the selection and development of appropriate road runoff treatment devices. Road runoff at an arterial road in Augsburg, Germany, has been studied for 3.5 years. A strong seasonal variation was observed, with increased heavy metal concentrations with doubled and tripled median concentrations for heavy metals during the cold season. Correlation analysis showed that de-icing salt is not the only factor responsible for increased pollutant concentrations in winter. During the cold period, the fraction of dissolved metals was lower compared to the warm season. In road dust, the highest metal concentrations were measured for fine particles. Metals in road runoff were found to show a significant correlation to fine particles SS63 (removal rates.

  13. Actinide transport in Topopah Spring Tuff: Pore size, particle size, and diffusion

    International Nuclear Information System (INIS)

    Buchholtz ten Brink, M.; Phinney, D.L.; Smith, D.K.

    1991-04-01

    Diffusive transport rates for aqueous species in a porous medium are a function of sorption, molecular diffusion, and sample tortuosity. With heterogeneous natural samples, an understanding of the effect of multiple transport paths and sorption mechanisms is particularly important since a small amount of radioisotope traveling via a faster-than-anticipated transport path may invalidate the predictions of transport codes which assume average behavior. Static-diffusion experiments using aqueous 238 U tracer in tuff indicated that U transport was faster in regions of greater porosity and that apparent diffusion coefficients depended on the scale (m or μm) over which concentration gradients were measured in Topopah Spring Tuff. If a significant fraction of actinides in high-level waste are released to the environment in forms that do not sorb to the matrix, they may be similarly transported along fast paths in porous regions of the tuff. To test this, aqueous diffusion rates in tuff were measured for 238 U and 239 Pu leached from doped glass. Measured transport rates and patterns were consistent in both systems with a dual-porosity transported moeld. In addition, filtration or channelling of actinides associated with colloidal particles may significantly affect the radionuclide transport rate in Topopah Spring tuff. 9 refs., 7 figs

  14. Isolation, characterization, and stability of discretely-sized nanolipoprotein particles assembled with apolipophorin-III.

    Directory of Open Access Journals (Sweden)

    Nicholas O Fischer

    Full Text Available BACKGROUND: Nanolipoprotein particles (NLPs are discoidal, nanometer-sized particles comprised of self-assembled phospholipid membranes and apolipoproteins. NLPs assembled with human apolipoproteins have been used for myriad biotechnology applications, including membrane protein solubilization, drug delivery, and diagnostic imaging. To expand the repertoire of lipoproteins for these applications, insect apolipophorin-III (apoLp-III was evaluated for the ability to form discretely-sized, homogeneous, and stable NLPs. METHODOLOGY: Four NLP populations distinct with regards to particle diameters (ranging in size from 10 nm to >25 nm and lipid-to-apoLp-III ratios were readily isolated to high purity by size exclusion chromatography. Remodeling of the purified NLP species over time at 4 degrees C was monitored by native gel electrophoresis, size exclusion chromatography, and atomic force microscopy. Purified 20 nm NLPs displa