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Sample records for characteristics particle size

  1. Characteristics of flow in wet conical spouted beds of unequal-sized spherical Particles

    OpenAIRE

    M. S. Bacelos; PASSOS M. L.; J. T. Freire

    2008-01-01

    Interparticle forces, developed in wet spouted beds composed of a mixture of spherical particles with different size distributions, intensify particle segregation mechanisms interfering in gas distribution inside the bed and, consequently, in the spouting flow characteristics. Therefore, this paper is aimed at describing the effect of interparticle forces on the air-solid flow distribution in conical spouted beds of unequal-sized particles coated by a thin glycerol film. Experimental results ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-15

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

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

    International Nuclear Information System (INIS)

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

  4. Coalbed methane adsorption and desorption characteristics related to coal particle size

    Science.gov (United States)

    Yan-Yan, Feng; Wen, Yang; Wei, Chu

    2016-06-01

    Effects of particle size on CH4 and CO2 adsorption and desorption characteristics of coals are investigated at 308 K and pressures up to 5.0 MPa. The gas adsorption and desorption isotherms of coals with particle sizes ranging from 250 μm to 840 μm are measured via the volumetric method, and the Langmuir model is used to analyse the experimental results. Coal particle size is found to have an obvious effect on the coal pore structure. With the decrease of coal particle size in the process of grinding, the pore accessibility of the coal, including the specific surface area and pore volume, increases. Hence, coal with smaller particle size has higher specific surface area and higher pore volume. The ability of adsorption was highly related to the pore structure of coal, and coal particle size has a significant influence on coal adsorption/desorption characteristics, including adsorption capacity and desorption hysteresis for CH4 and CO2, i.e., coal with a smaller particle size achieves higher adsorption capacity, while the sample with a larger particle size has lower adsorption capacity. Further, coal with larger particle size is also found to have relatively large desorption hysteresis. In addition, dynamic adsorption performances of the samples are carried out at 298 K and at pressures of 0.1 MPa and 0.5 MPa, respectively, and the results indicate that with the increase of particle size, the difference between CO2 and CH4 adsorption capacities of the samples decreases. Project supported by the National Basic Research Program of China (Grant No. 2011CB201202).

  5. Particle number size distribution and new particle formation:New characteristics during the special pollution control period in Beijing

    Institute of Scientific and Technical Information of China (English)

    Jian Gao; Fahe Chai; Tao Wang; Shulan Wang; Wenxing Wang

    2012-01-01

    New particle formation is a key process in shaping the size distribution of aerosols in the atmosphere.We present here the measurement results of number and size distribution of aerosol particles (10-10000 nm in diameter) obtained in the summer of 2008,at a suburban site in Beijing,China.We firstly reported the pollution level,particle number size distribution,diurnal variation of the particle number size distribution and then introduced the characteristics of the particle formation processes.The results showed that the number concentration of ultrafine particles was much lower than the values measured in other urban or suburban areas in previous studies.Sharp increases of ultrafine particle count were frequently observed at noon.An examination of the diurnal pattern suggested that the burst of ultrafine particles was mainly due to new particle formation promoted by photochemical processes.In addition,high relative humidity was a key factor driving the growth of the particles in the afternoon.During the 2-month observations,new particle formation from homogeneous nucleation was observed for 42.7% of the study period.The average growth rate of newly formed particles was 3.2 nm/hr,and varied from 1.2 to 8.0 nm/hr.The required concentration of condensable vapor was 4.4 × 107 cm-3,and its source rate was 1.2 × 106 cm-3sec-1.Further calculation on the source rate of sulphuric acid vapor indicated that the average participation of sulphuric acid to particle growth rates was 28.7%.

  6. Influence of Coal Particle Size on Coal Adsorption and Desorption Characteristics

    Science.gov (United States)

    Zhang, Lei; Aziz, Naj; Ren, Ting; Nemcik, Jan; Tu, Shihao

    2014-10-01

    Accurate testing coal isotherm can play a significant role in the areas of coal seam gas drainage, outburst control, CO2 geo-sequestration, coalbed methane (CBM) and enhanced coalbed methane recovery (ECBM) etc. The effect of particle size on the CO2 and CH4 sorption capacity of bituminous coal from Illawarra, Australia was investigated at 35°C and at pressure up to 4 MPa. A unique indirect gravimetric apparatus was used to measure the gas adsorption and desorption isotherms of coal of different particle sizes ranging from around 150 urn to 16 mm. Langmuir model was used to analysis the experimental results of all gases. Coal particle size was found to have an apparent effect on the coal ash content and helium density results. Coal with larger particle size had higher ash content and higher helium density. The sorption isotherm was found to be highly sensitive with helium density of coal which was determined in the procedure of testing the void volume of sample cell. Hence, coal particle size had a significant influence on the coal sorption characteristics including sorption capacity and desorption hysteresis for CO2 and CH4, especially calculated with dry basis of coal. In this study, the 150-212 um (150 um) coal samples achieved higher sorption capacity and followed by 2.36-3.35 mm (2.4 mm), 8-9.5 mm (8 mm) and 16-19 mm (16 mm) particle size samples. However, the differences between different coal particles were getting smaller when the sorption isotherms are calculated with dry ash free basis. Test with 150 um coal samples were also found to have relatively smaller desorption hysteresis compared with the other larger particle size samples. The different results including adsorption/desorption isotherm, Langmuir parameters and coal hysteresis were all analysed with the CO2 and CH4 gases.

  7. Characteristics and sources of intermediate size particles in recovery boilers : final project report.

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, Larry L. (Brigham Young University, Provo, UT); Shaddix, Christopher R.; Verrill, Christopher L. (Georgia Institute of Technology, Institute of Paper Science and Technology, Atlanta, GA); Wessel, Richard A. (Babcock & Wilcox Company, Barberton, OH)

    2005-02-01

    As part of the U.S. Department of Energy (DOE) Office of Industrial Technologies (OIT) Industries of the Future (IOF) Forest Products research program, a collaborative investigation was conducted on the sources, characteristics, and deposition of particles intermediate in size between submicron fume and carryover in recovery boilers. Laboratory experiments on suspended-drop combustion of black liquor and on black liquor char bed combustion demonstrated that both processes generate intermediate size particles (ISP), amounting to 0.5-2% of the black liquor dry solids mass (BLS). Measurements in two U.S. recovery boilers show variable loadings of ISP in the upper furnace, typically between 0.6-3 g/Nm{sup 3}, or 0.3-1.5% of BLS. The measurements show that the ISP mass size distribution increases with size from 5-100 {micro}m, implying that a substantial amount of ISP inertially deposits on steam tubes. ISP particles are depleted in potassium, chlorine, and sulfur relative to the fuel composition. Comprehensive boiler modeling demonstrates that ISP concentrations are substantially overpredicted when using a previously developed algorithm for ISP generation. Equilibrium calculations suggest that alkali carbonate decomposition occurs at intermediate heights in the furnace and may lead to partial destruction of ISP particles formed lower in the furnace. ISP deposition is predicted to occur in the superheater sections, at temperatures greater than 750 C, when the particles are at least partially molten.

  8. Characteristics of flow in wet conical spouted beds of unequal-sized spherical Particles

    Directory of Open Access Journals (Sweden)

    M. S. Bacelos

    2008-03-01

    Full Text Available Interparticle forces, developed in wet spouted beds composed of a mixture of spherical particles with different size distributions, intensify particle segregation mechanisms interfering in gas distribution inside the bed and, consequently, in the spouting flow characteristics. Therefore, this paper is aimed at describing the effect of interparticle forces on the air-solid flow distribution in conical spouted beds of unequal-sized particles coated by a thin glycerol film. Experimental results show that both the minimum spouting airflow rate and the minimum spouting pressure drop decrease as the amount of glycerol added to the bed increases. In addition, simulated results of the annular air velocity along the bed height showed that, at the base of the column, the radial component of the inertial force is high enough to break liquid bridges between particles and carry these particles out along the spout. Moreover, as the glycerol concentration increases, the spout diameter increases along the bed height. Such changes in the air-solid flow can maintain the spouting regime for higher glycerol concentrations as shown by experimental data.

  9. Effect of drug substance particle size on the characteristics of granulation manufactured in a high-shear mixer

    OpenAIRE

    Badawy, Sherif I. Farags; Lee, Tara J.; Menning, Mark M.

    2000-01-01

    DPC 963 is a non-nucleoside reverse transcriptase inhibitor with low aqueous solubility. The effect of DPC 963 drug substance particle size on the characteristics of granules manufactured by high-shear wet granulation was evaluated. The wet granulation process was used to manufacture a DPC 963 formulation with high drug loading. The formulation was manufactured using drug substance lots with different particle size distributions. Granulation particle size distribution, porosity, and compressi...

  10. Characteristics of atmospheric particulate mercury in size-fractionated particles during haze days in Shanghai

    Science.gov (United States)

    Chen, Xiaojia; Balasubramanian, Rajasekhar; Zhu, Qiongyu; Behera, Sailesh N.; Bo, Dandan; Huang, Xian; Xie, Haiyun; Cheng, Jinping

    2016-04-01

    Atmospheric particulate mercury (PHg) is recognized as a global pollutant that requires regulation because of its significant impacts on both human health and wildlife. The haze episodes that occur frequently in China could influence the transport and fate of PHg. To examine the characteristics of PHg during haze and non-haze days, size-fractioned particles were collected using thirteen-stage Nano-MOUDI samplers (10 nm-18 μm) during a severe haze episode (from December 2013 to January 2014) in Shanghai. The PHg concentration on haze days (4.11 ± 0.53 ng m-3) was three times higher than on non-haze days (1.34 ± 0.15 ng m-3). The ratio of the PHg concentration to total gaseous mercury (TGM) ranged from 0.42 during haze days to 0.21 during non-haze days, which was possibly due to the elevated concentration of particles for gaseous elemental mercury (GEM) adsorption, elevated sulfate and nitrate contributing to GEM oxidation, and the catalytic effect of elevated water-soluble inorganic metal ions. PHg/PM10 during haze days (0.019 ± 0.004 ng/μg) was lower than during non-haze days (0.024 ± 0.002 ng/μg), and PHg/PM10 was significantly reduced with an increasing concentration of PM10, which implied a relatively lower growth velocity of mercury than other compositions on particles during haze days, especially in the diameter range of 0.018-0.032 μm. During haze days, each size-fractioned PHg concentration was higher than the corresponding fraction on non-haze days, and the dominant particle size was in the accumulation mode, with constant accumulation to a particle size of 0.56-1.0 μm. The mass size distribution of PHg was bimodal with peaks at 0.32-0.56 μm and 3.1-6.2 μm on non-haze days, and 0.56-1.0 μm and 3.1-6.2 μm on haze days. There was a clear trend that the dominant size for PHg in the fine modes shifted from 0.32-0.56 μm during non-haze days to 0.56-1.0 μm on haze days, which revealed the higher growth velocity of PHg on haze days due to the

  11. Predicting Soil-Water Characteristics from Volumetric Contents of Pore-Size Analogue Particle Fractions

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Møldrup, Per; Tuller, Markus;

    the SWC, derived from readily available soil properties such as texture and bulk density. A total of 46 soils from different horizons at 15 locations across Denmark were used for models evaluation. The Xw-model predicts the volumetric water content as a function of volumetric fines content (organic......Modelling water distribution and flow in partially saturated soils requires knowledge of the soil-water characteristic (SWC). However, measurement of the SWC is challenging and time-consuming, and in some cases not feasible. This study introduces two predictive models (Xw-model and Xw*-model) for...... matter and clay). It performed reasonably well for the dry-end (above a pF value of 2.0; pF = log(|Ψ|), where Ψ is the matric potential in cm), but did not do as well closer to saturated conditions. The Xw*-model gives the volumetric water content as a function of volumetric content of particle size...

  12. Effects of forage type, animal characteristics and feed intake on faecal particle size in goat, sheep, llama and cattle

    DEFF Research Database (Denmark)

    Jalali, A.R.; Weisbjerg, Martin Riis; Nadeau, E.;

    2015-01-01

    The effect of forage maturity stage at harvest, animal characteristics and neutral detergent fibre (NDF) intake on mean particle size and particle size distribution in faeces from sheep and cattle fed grass silages was studied (Study I). Models for prediction of faeces characteristics from sheep ...... size in faeces from goat, sheep, llama and steers fed other forages e.g., lucerne, dried grass, grass seed straw and whole crop barley silage in Study II.......The effect of forage maturity stage at harvest, animal characteristics and neutral detergent fibre (NDF) intake on mean particle size and particle size distribution in faeces from sheep and cattle fed grass silages was studied (Study I). Models for prediction of faeces characteristics from sheep...... in faeces and this effect was amplified in larger animals. The prediction model established from Study I, on the effect of BW, ADL/NDF in forage, C:F and forage NDF intake on particle size in faeces of grass silage-fed animals in Study I appeared to be valid to predict the geometric mean particle...

  13. Chemical characteristics and source of size-fractionated atmospheric particle in haze episode in Beijing

    Science.gov (United States)

    Tan, Jihua; Duan, Jingchun; Zhen, Naijia; He, Kebin; Hao, Jiming

    2016-01-01

    The abundance, behavior, and source of chemical species in size-fractionated atmospheric particle were studied with a 13-stage low pressure impactor (ELPI) during high polluted winter episode in Beijing. Thirty three elements (Al, Ca, Fe, K, Mg, Na, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, and Pb) and eight water soluble ions (Cl-, NO3-, SO42 -, NH4+, Na+, K+, Ca2 +, and Mg2 +) were determined by ICP/MS and IC, respectively. The size distribution of TC (OC + EC) was reconstructed. Averagely, 51.5 ± 5.3% and 74.1 ± 3.7% of the total aerosol mass was distributed in the sub-micron (PM1) and fine particle (PM2.5), respectively. A significant shift to larger fractions during heavy pollution episode was observed for aerosol mass, NH4+, SO42 -, NO3-, K, Fe, Cu, Zn, Cd, and Pb. The mass size distributions of NH4+, SO42 -, NO3-, and K were dominated by accumulation mode. Size distributions of elements were classified into four main types: (I) elements were enriched within the accumulation mode (water soluble ions. Dust, vehicle, aged coal combustion, and sea salt were identified, and the size resolved source apportionments were discussed. Aged coal combustion was the important source of fine particles and dust contributed most to coarse particle.

  14. Battery condenser system particulate emission factors for cotton gins: Particle size distribution characteristics

    Science.gov (United States)

    This report is part of a project to characterize cotton gin emissions from the standpoint of total particulate stack sampling and particle size analyses. In 2013, the Environmental Protection Agency (EPA) published a more stringent standard for particulate matter with nominal diameter less than or e...

  15. Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles

    Directory of Open Access Journals (Sweden)

    K. Wittmaack

    2005-04-01

    Full Text Available Combustion of elemental carbon (EC and organic carbon (OC contained in ambient aerosol matter was explored using scanning electron microscopy (SEM in combination with energy dispersive X-ray analysis (EDX. To ease identification of the particles of interest and to avoid or at least reduce interaction with simultaneously sampled inorganic oxides and salts, the approach used in this work differed in two ways from commonly applied procedures. First, rather than using a mixture of particles of vastly different sizes, as in PM10 or PM2.5, aerosol matter was collected in a 5-stage impactor. Second, the water soluble fraction of the collected matter was removed prior to analysis. Diesel soot particles, which appeared in the well-known form of chain-type aggregates, constituted the major fraction of EC. In contrast, OC containing particles were observed in a variety of shapes, including a sizable amount of bioaerosol matter appearing mostly in the size range above about 1 µm. During heating in ambient air for 1 h, diesel soot particles were found to be stable up to 480°C, but complete combustion occurred in a narrow temperature interval between about 490 and 510°C. After diesel soot combustion, minute quantities of ''ash'' were observed in the form of aggregated tiny particles with sizes less than 10 nm. These particles could be due to elemental or oxidic contaminants of diesel soot. Combustion of OC was observed over a wide range of temperatures, from well below 200°C to at least 500°C. Incompletely burnt bioaerosol matter was still found after heating to 600°C. The results imply that the EC fraction in aerosol matter can be overestimated significantly if the contribution of OC to a thermogram is not well separated.

  16. Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles

    Directory of Open Access Journals (Sweden)

    K. Wittmaack

    2005-01-01

    Full Text Available Combustion of elemental carbon (EC and organic carbon (OC contained in ambient aerosol matter was explored using scanning electron microscopy (SEM in combination with energy dispersive X-ray analysis (EDX. To ease identification of the particles of interest and to avoid or at least reduce interaction with simultaneously sampled inorganic oxides and salts, the approach used in this work differed in two ways from commonly applied procedures. First, rather than using a mixture of particles of vastly different sizes, as in PM10 or PM2.5, aerosol matter was collected in a 5-stage impactor. Second, the water soluble fraction of the collected matter was removed prior to analysis. Diesel soot particles, which appeared in the well-known form of chain-type aggregates, constituted the major fraction of EC. In contrast, OC containing particles were observed in a variety of shapes, including a sizable amount of bioaerosol matter appearing mostly in the size range above about 1 µm. During heating in ambient air for 1h, diesel soot particles were found to be stable up to 470°C, but complete combustion occurred in a narrow temperature interval between about 480 and 510°C. After diesel soot combustion, minute quantities of 'ash' were observed in the form of aggregated tiny particles with sizes less than 10 nm. These particles could be due to elemental or oxidic contaminants of diesel soot. Combustion of OC was observed over a wide range of temperatures, from well below 200°C to at least 500°C. Incompletely burnt bioaerosol matter was still found after heating to 600°C. The results imply that the EC fraction in aerosol matter can be overestimated significantly if the contribution of OC to a thermogram is not well separated.

  17. Effects of supplementation level and particle size of alfalfa hay on growth characteristics and rumen development in dairy calves

    NARCIS (Netherlands)

    Mirzaei, M.; Khorvash, M.; Ghorbani, G.R.; Kazemi-Bonchenari, M.; Riasi, A.; Nabipour, A.; Borne, van den J.J.G.C.

    2015-01-01

    The aim of this study was to assess the effects of particle size (PS) of alfalfa hay on growth characteristics and rumen development in dairy calves at two levels of alfalfa supplementation. Fifty newborn dairy calves (42.7 ± 2.2 kg BW) were used in a 2 × 2 factorial arrangement with the factors sup

  18. Predicting Soil Moisture Characteristic Curves from Continuous Particle-Size Distribution Data

    Institute of Scientific and Technical Information of China (English)

    M.H.MOHAMMADI; F.MESKINI-VISHKAEE

    2013-01-01

    Soil moisture characteristic curve (SMC) is a fundamental soil property and its direct measurement is tedious and time consuming.Therefore,various indirect methods have been developed to predict SMC from particle-size distribution (PSD).However,the majority of these methods often yield intermittent SMC data because they involve estimating individual SMC points.The objectives of this study were 1) to develop a procedure to predict continuous SMC from a limited number of experimental PSD data points and 2) to evaluate model predictions through comparisons with measured values.In this study,an approach that allowed predicting SMC from the knowledge of PSD,parameterized by means of the closed-form van Genuchten model (VG),was used.Through using Moharnmadi and Vanclooster (MV) model,the parameters obtained from fitting of VG to PSD data were applied to predict SMC curves.Since the residual water content (θr) could not be obtained through fitting of VG-MV integrated model to PSD data,we also examined and compared four different methods estimating θr.Results showed that the proposed equation (MV-VG integrated model) provided an excellent fit to all the PSD data and the model could adequately predict SMC as measured in forty-two soils sampled from different regions of Iran.For all soils,the method in which θr was obtained through parameter optimization procedure provided the best overall predictions of SMC.The two methods estimating θr with Campbell and Shiozawa (CS) model resulted in less accuracy than the optimization procedure.Furthermore,the proposed model underestimated the moisture content in the dry range of SMC when the value of θr was assumed to equal zero.θr could be attributed to the incomplete desorption of water coated on soil particles and the accurate estimation of θr was critical in prediction of SMC,especially for fine-textured soils at high suction heads.It could be concluded that the advantages of our approach were the continuity

  19. Influence of the glass particle size on the foaming process and physical characteristics of foam glasses

    DEFF Research Database (Denmark)

    König, Jakob; Petersen, Rasmus Rosenlund; Yue, Yuanzheng

    2016-01-01

    We have prepared low-density foam glasses from cathode-ray-tube panel glass using carbon and MnO2 as the foaming agents. The effect of the glass particle size on the foaming process, the apparent density and the pore morphology is revealed. The results show that the foaming is mainly caused by the...... reduction of manganese. Foam glasses with a density of <150 kg m−3 are obtained when the particle size is ≤33 μm (D50). The foams have a homogeneous pore distribution and a major fraction of the pores are smaller than 0.5 mm. Only when using the smallest particles (13 μm) does the pore size increase to 1......–3 mm due to a faster coalescence process. However, by quenching the sample from the foaming to the annealing temperature the pore size is reduced by a factor of 5–10. The foams with an apparent density of <200 kg m−3 are predominantly open-porous. The foams exhibit a thermal conductivity as lowas 38.1m...

  20. Chemical characteristics and source of size-fractionated atmospheric particle in haze episode in Beijing

    Science.gov (United States)

    Tan, Jihua; Duan, Jingchun; Zhen, Naijia; He, Kebin; Hao, Jiming

    2016-01-01

    The abundance, behavior, and source of chemical species in size-fractionated atmospheric particle were studied with a 13-stage low pressure impactor (ELPI) during high polluted winter episode in Beijing. Thirty three elements (Al, Ca, Fe, K, Mg, Na, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, and Pb) and eight water soluble ions (Cl-, NO3-, SO42 -, NH4+, Na+, K+, Ca2 +, and Mg2 +) were determined by ICP/MS and IC, respectively. The size distribution of TC (OC + EC) was reconstructed. Averagely, 51.5 ± 5.3% and 74.1 ± 3.7% of the total aerosol mass was distributed in the sub-micron (PM1) and fine particle (PM2.5), respectively. A significant shift to larger fractions during heavy pollution episode was observed for aerosol mass, NH4+, SO42 -, NO3-, K, Fe, Cu, Zn, Cd, and Pb. The mass size distributions of NH4+, SO42 -, NO3-, and K were dominated by accumulation mode. Size distributions of elements were classified into four main types: (I) elements were enriched within the accumulation mode (fine, intermediate, and coarse modes; and (IV) those which were mainly found within particles larger than 2.7 μm (Al, Mg, Si, Ca, Sc, Tl, Fe, Sr, Zr, and Ba). [H+]cor showed an accumulation mode at 600-700 nm and the role of Ca2 + should be fully considered in the estimation of acidity. The acidity in accumulation mode particles suggested that generally gaseous NH3 was not enough to neutralize sulfate completely. PMF method was applied for source apportionment of elements combined with water soluble ions. Dust, vehicle, aged coal combustion, and sea salt were identified, and the size resolved source apportionments were discussed. Aged coal combustion was the important source of fine particles and dust contributed most to coarse particle.

  1. A Characteristic Particle Length

    CERN Document Server

    Roberts, Mark D

    2015-01-01

    It is argued that there are characteristic intervals associated with any particle that can be derived without reference to the speed of light $c$. Such intervals are inferred from zeros of wavefunctions which are solutions to the Schr\\"odinger equation. The characteristic length is $\\ell=\\beta^2\\hbar^2/(8Gm^3)$, where $\\beta=3.8\\dots$; this length might lead to observational effects on objects the size of a virus.

  2. Particle Size Analysis.

    Science.gov (United States)

    Barth, Howard G.; Sun, Shao-Tang

    1989-01-01

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

  3. Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles

    OpenAIRE

    Wittmaack, K.

    2005-01-01

    Combustion of elemental carbon (EC) and organic carbon (OC) contained in ambient aerosol matter was explored using scanning electron microscopy (SEM) in combination with energy dispersive X-ray analysis (EDX). To ease identification of the particles of interest and to avoid or at least reduce interaction with simultaneously sampled inorganic oxides and salts, the approach used in this work differed in two ways from commonly applied procedures. First, rather than using a mixture of particles o...

  4. The characteristics of nano-sized Gd-doped CeO2 particles prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Gd-doped ceria particles with nanometer size were prepared by spray pyrolysis from spray solution containing ethylene glycol. The effect of ethylene glycol and gadolinium dopant on the morphology of the ceria particles prepared by spray pyrolysis was investigated. The Gd-doped ceria particles prepared from pure aqueous solution had submicron size, spherical shape and dense structure after post-treatment. The Gd-doped ceria particles prepared from solution containing ethylene glycol had loosely aggregated structure of the primary particles with nanometer size after post-treatment at 900 and 1050 deg. C. The Gd-doped ceria particles had more loosely aggregated and regular morphology than the pure ceria particles at the post-treatment temperature of 900 deg. C. The gadolinium component used as dopant suppressed grain growth in ceria particles prepared by spray pyrolysis. Nanometer size Gd-doped ceria particles were prepared by a ball milling process of the particles obtained by spray pyrolysis. The mean size of the Gd-doped ceria particles was 46 nm after a post-treatment at 1050 deg. C. The ionic conductivity of the Gd-doped ceria particles prepared by spray pyrolysis was compared with that of the commercial yttria-stabilized zirconia (YSZ)

  5. Correlation between particle size and magnetic characteristics of Mn-substituted ZnFe2O4 ferrites

    Science.gov (United States)

    Zawar, Sidra; Atiq, Shahid; Riaz, Saira; Naseem, Shahzad

    2016-05-01

    We report synthesis of Zn1-xMnxFe2O4 (x = 0.0, 0.1, 0.3, 0.4 & 0.5) ferrites using sol-gel auto-combustion route while citric acid is used as a fuel. The study is aimed to explore the influence of Mn contents on structural parameters, morphological characteristics and magnetic properties of ZnFe2O4 ferrite samples while the impact of average grain dimensions on magnetic properties inferred from multi domain and single domain particle's effect is also analyzed. X-ray diffraction confirmed the configuration of single phase pure crystalline structure with low concentration of Mn while some impurity peaks were found for higher Mn contents. Lattice parameter was found to increase with increasing Mn contents while crystallite size was decreased. Average grain size was decreased from 240 to 150 nm with increasing Mn concentration which directly affected the magnetic properties. A decrease in saturation magnetization (from 52.35 to 45.80 emu/g) and an increase in coercivity (from 44 to 262 Oe) was observed with increasing Mn contents. A decrease in initial permeability and increase in hysteresis loss with increasing Mn contents was also evident. Coercive field and hysteresis losses were increased with decreasing average grain size while initial permeability was found to decrease with decrease in average grain size.

  6. Effect of particle size and particle size distribution on physical characteristics, morphology and crystal strucutre of explosively compacted high-Tc superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kotsis, I.; Enisz, M.; Oravetz, D. [Univ. of Veszprem (Hungary)] [and others

    1994-12-31

    A superconductor, of composition Y(Ba,K,Na){sub 2}Cu{sub 3}O{sub x}/F{sub y} and a composite, of composition Y(Ba,K,Na){sub 2}Cu{sub 3}O{sub x}/F{sub y}+Ag, with changing K, Na and F content, but a constant silver content (Ag=10 mass per cent) was prepared using a single heat treatment. The resulting material was ground in a corundum lined mill, separated to particle size fractions of 0-40 {mu}m, 0-63 {mu}m and 63-900 {mu}m and explosively compacted, using an explosive pressure of 10{sup 4} MPa and a subsequent heat treatment. Best results were obtained with the 63-900 {mu}m fraction of composition Y(Ba{sub 1,95}K{sub 0,01})Cu{sub 3}O{sub x}F{sub 0,05}/Ag: porosity <0.01 cm{sup 3}/g and current density 2800 A/cm{sup 2} at 77 K.

  7. Characteristics of Cu–Al2O3 composites of various starting particle size obtained by high-energy milling

    Directory of Open Access Journals (Sweden)

    VIŠESLAVA RAJKOVIĆ

    2009-05-01

    Full Text Available The powder Cu– Al2O3 composites were produced by high-energy milling. Various combinations of particle size and mixtures and approximately constant amount of Al2O3 were used as the starting materials. These powders were separately milled in air for up to 20 h in a planetary ball mill. The copper matrix was reinforced by internal oxidation and mechanical alloying. During the milling, internal oxidation of pre-alloyed Cu-2 mass %-Al powder generated 3.7 mass % Al2O3 nano-sized particles finely dispersed in the copper matrix. The effect of different size of the starting copper and Al2O3 powder particles on the lattice parameter, lattice distortion and grain size, as well as on the size, morphology and microstructure of the Cu– Al2O3 composite powder particles was studied.

  8. Particle sizes from sectional data

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  9. Effect of kaolin particle size and loading on the characteristics of kaolin ceramic support prepared via phase inversion technique

    OpenAIRE

    Siti Khadijah Hubadillah; Zawati Harun; Mohd Hafiz Dzarfan Othman; A. F. ISMAIL; Paran Gani

    2016-01-01

    In this study, low cost ceramic supports were prepared from kaolin via phase inversion technique with two kaolin particle sizes, which are 0.04–0.6 μm (denoted as type A) and 10–15 μm (denoted as type B), at different kaolin contents ranging from 14 to 39 wt.%, sintered at 1200 °C. The effect of kaolin particle sizes as well as kaolin contents on membrane structure, pore size distribution, porosity, mechanical strength, surface roughness and gas permeation of the support were investigated. Th...

  10. Fluidization Characteristics of Silicon Particles with a Wide Size Distribution%宽筛分硅粉颗粒的流化特性

    Institute of Scientific and Technical Information of China (English)

    罗务习; 梁卫华; 张国良; 王金福

    2004-01-01

    Fluidization characteristics of silicon particle system are studied by the pressure fluctuation method.The existence of fine particles in the system can improve fluidization. Silicon particles with a wide size distribution,preferably with some fines, behave as Group A particles according to Geldart classification, although the system belongs to Group B actually. The system is also approved to be suitable for organochlorosilane monomer production using a fluidized bed reactor. Experimental data obtained in this work are important for the design and operation of commercial fluidized bed reactors for the production of organochlorosilane monomers.

  11. The Relations Between Soil Water Retention Characteristics, Particle Size Distributions, Bulk Densities and Calcium Carbonate Contents for Danish Soils

    DEFF Research Database (Denmark)

    Jensen, Niels H.; Balstrøm, Thomas; Breuning-Madsen, Henrik

    2005-01-01

    A database containing about 800 soil profiles located in a 7-km grid covering Denmark has been used to develop a set of regression equations of soil water content at pressure heads –1, -10, -100 and –1500 kPa versus particle size distribution, organic matter, CaCO3 and bulk density. One purpose was...... to elaborate equations based of soil parameters available in the Danish Soil Classification's texture database on particle size distribution and organic matter. It was also tested if inclusion of bulk density or CaCO3 content (in CaCO3-containing samples) as predictors or grouping in surface and...... pedotransfer functions developed in HYPRES (Hydraulic Properties of European Soils). Introducing bulk density as a predictor improved the equation for pressure head –1 kPa but not for lower ones. The grouping of data sets in surface and subsurface horizons or in textural classes did not improve the equations...

  12. The Influence of Synthesis Parameters on Particle Size and Photoluminescence Characteristics of Ligand Capped Tb3+:LaF3

    Directory of Open Access Journals (Sweden)

    Phil Brown

    2011-11-01

    Full Text Available Organic ligand surface-treated Tb3+:LaF3 was synthesized in water and methanol for subsequent incorporation into polymethyl methacrylate (PMMA via solution-precipitation chemistry in order to produce optically active polymer nanocomposites. Nanoparticle agglomerate diameters ranged from 388 ± 188 nm when synthesized in water and 37 ± 2 nm when synthesized in methanol. Suspension stability is paramount for producing optically transparent materials. Methanol nanoparticle synthesized at a pH of 3 exhibited the smallest agglomerate size. Optical spectroscopy, dynamic light scattering, transmission electron microscopy, scanning transmission electron microscopy, and zeta potential analysis were used to characterize the particles synthesized.

  13. Adsorption capacities of activated carbons for geosmin and 2-methylisoborneol vary with activated carbon particle size: Effects of adsorbent and adsorbate characteristics.

    Science.gov (United States)

    Matsui, Yoshihiko; Nakao, Soichi; Sakamoto, Asuka; Taniguchi, Takuma; Pan, Long; Matsushita, Taku; Shirasaki, Nobutaka

    2015-11-15

    The adsorption capacities of nine activated carbons for geosmin and 2-methylisoborneol (MIB) were evaluated. For some carbons, adsorption capacity substantially increased when carbon particle diameter was decreased from a few tens of micrometers to a few micrometers, whereas for other carbons, the increase of adsorption capacity was small for MIB and moderate for geosmin. An increase of adsorption capacity was observed for other hydrophobic adsorbates besides geosmin and MIB, but not for hydrophilic adsorbates. The parameter values of a shell adsorption model describing the increase of adsorption capacity were negatively correlated with the oxygen content of the carbon among other characteristics. Low oxygen content indicated low hydrophilicity. The increase of adsorption capacity was related to the hydrophobic properties of both adsorbates and activated carbons. For adsorptive removal of hydrophobic micropollutants such as geosmin, it is therefore recommended that less-hydrophilic activated carbons, such as coconut-shell-based carbons, be microground to a particle diameter of a few micrometers to enhance their equilibrium adsorption capacity. In contrast, adsorption by hydrophilic carbons or adsorption of hydrophilic adsorbates occur in the inner pores, and therefore adsorption capacity is unchanged by particle size reduction. PMID:26302219

  14. Effects of distance between tungsten wire and glass substrate on particle size and photochromic characteristic of tungsten oxide prepared by electric current heating method

    Energy Technology Data Exchange (ETDEWEB)

    Hagizawa, T; Honma, T; Kuroki, Y; Okamoto, T; Takata, M, E-mail: takata@vos.nagaokaut.ac.jp [Department of Electrical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188 (Japan)

    2011-10-29

    Tungsten oxide films consisting of particles were prepared on the substrates placed at various distances from the tungsten wires heated by electric current. The shapes of the particles were sphere in an area on the substrate just above the wire while octahedral shape was found in other area. For the spherical particles, with increasing the distance, the mean particle diameter increased, reached its maximum value and gradually decreased. The particles in each area showed the photochromism especially in near-infrared region. The spherical particles with the smallest size exhibited a significant photochromic effect which could be controlled by changing the distance between the wire and the substrate.

  15. Effects of distance between tungsten wire and glass substrate on particle size and photochromic characteristic of tungsten oxide prepared by electric current heating method

    International Nuclear Information System (INIS)

    Tungsten oxide films consisting of particles were prepared on the substrates placed at various distances from the tungsten wires heated by electric current. The shapes of the particles were sphere in an area on the substrate just above the wire while octahedral shape was found in other area. For the spherical particles, with increasing the distance, the mean particle diameter increased, reached its maximum value and gradually decreased. The particles in each area showed the photochromism especially in near-infrared region. The spherical particles with the smallest size exhibited a significant photochromic effect which could be controlled by changing the distance between the wire and the substrate.

  16. Fabrication of Controllable Pore and Particle Size of Mesoporous Silica Nanoparticles via a Liquid-phase Synthesis Method and Its Absorption Characteristics

    Science.gov (United States)

    Nandiyanto, Asep Bayu Dani; Iskandar, Ferry; Okuyama, Kikuo

    2011-12-01

    Monodisperse spherical mesoporous silica nanoparticles were successfully synthesized using a liquid-phase synthesis method. The result showed particles with controllable pore size from several to tens nanometers with outer diameter of several tens nanometers. The ability in the control of pore size and outer diameter was altered by adjusting the precursor solution ratios. In addition, we have conducted the adsorption ability of the prepared particles. The result showed that large organic molecules were well-absorbed to the prepared silica porous particles, in which this result was not obtained when using commercial dense silica particle and/or hollow silica particle. With this result, the prepared mesoporous silica particles may be used efficiently in various applications, such as sensors, pharmaceuticals, environmentally sensitive pursuits, etc.

  17. COMPARISON OF VARIOUS PARTICLE SIZING TECHNIQUES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  18. [Distribution characteristics of lead in different particle size fractions of surface soil of a lead-acid battery factory contaminated site].

    Science.gov (United States)

    Yue, Xi; Sun, Ti-chang; Huang, Jin-lou

    2013-09-01

    In this research, six topsoil samples (0-20 cm) were collected in the heavy-metal lead contaminated soil of one lead battery factory in south-west China as research object, which were later divided into seven particle size fractions, and analyzed for the lead concentration as well as the correlation between the lead concentration and the organic matter content. The result showed that five soil samples were contaminated with lead with different pollution levels, and there were two different trends in the changes of lead concentration as of the change of soil particle size. The lead concentration of the three samples from sewage treatment workshop, the workshop A and the workshop B, showed a first declining and then ascending trend with the decreasing particle size. The lead concentration of the soil samples of the packing workshop and the former production workshop A showed a decreasing trend when the particle size decreased. The lead concentration and the organic matter content showed a positive linear correlation (R2 = 0.8232). Soil organic matter has the ability of lead enrichment, and the ability declines with the decreasing particle size. Soil texture may be an important factor for the interaction between soil organic matter and lead distribution. PMID:24289023

  19. Aerodynamic characteristics of popcorn ash particles

    Energy Technology Data Exchange (ETDEWEB)

    Cherkaduvasala, V.; Murphy, D.W.; Ban, H.; Harrison, K.E.; Monroe, L.S. [University of Alabama, Birmingham, AL (United States). Dept. of Mechanical Engineering

    2007-07-01

    Popcorn ash particles are fragments of sintered coal fly ash masses that resemble popcorn in low apparent density. They can travel with the flow in the furnace and settle on key places such as catalyst surfaces. Computational fluid dynamics (CFD) models are often used in the design process to prevent the carryover and settling of these particles on catalysts. Particle size, density, and drag coefficient are the most important aerodynamic parameters needed in CFD modeling of particle flow. The objective of this study was to experimentally determine particle size, shape, apparent density, and drag characteristics for popcorn ash particles from a coal-fired power plant. Particle size and shape were characterized by digital photography in three orthogonal directions and by computer image analysis. Particle apparent density was determined by volume and mass measurements. Particle terminal velocities in three directions were measured in water and each particle was also weighed in air and in water. The experimental data were analyzed and models were developed for equivalent sphere and equivalent ellipsoid with apparent density and drag coefficient distributions. The method developed in this study can be used to characterize the aerodynamic properties of popcorn-like particles.

  20. Particle size characterization by ultrasonic attenuation spectra

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  1. 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.

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

    Science.gov (United States)

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

    2002-12-01

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

  3. Experimental study of particle size distribution in suspension polymerization

    International Nuclear Information System (INIS)

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

  4. APSAS; an Automated Particle Size Analysis System

    Science.gov (United States)

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

    1985-01-01

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

  5. PARAMETERS AFFECTING PARTICLE SIZE OF POLYBUTYLACRYLATE MICROGELS

    Institute of Scientific and Technical Information of China (English)

    WANG Xia; YU Yunzhao

    1989-01-01

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

  6. ISO INTERNATIONAL STANDARDS FOR PARTICLE SIZING

    Institute of Scientific and Technical Information of China (English)

    Renliang Xu

    2004-01-01

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

  7. Hazards of explosives dusts: Particle size effects

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-02-01

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

  8. Soil Development and Fertility Characteristics of Inland Valleys in the Rain Forest Zone of Nigeria:Mineralogical Composition and Particle-Size Distribution

    Institute of Scientific and Technical Information of China (English)

    S.S.ABE; G.O.OYEDIRAN; T.MASUNAGA; S.YAMAMOTO; T.HONNA; T.WAKATSUKI

    2009-01-01

    The particle-size distribution and mineralogical composition of the clay (<2 μm) and fine-sand (0.25-0.10 mm)fractions in soils of two inland valleys in Abakaliki and Bende,Southeast Nigeria,were investigated to provide basic information on soil-forming processes and agricultural potentials.These soils were silty or clayey,deriving from Cretaceous or Tertiary shale materials.The particle-size distribution and its computation on a clay-free basis revealed relatively remarkable lithologic breaks in a couple of pedons.The effect of lithologic discontinuities on soil mineralogical composition was not,however,conspicuous.Petrographic investigation revealed that quartz predominantly comprised the fine-sand fraction in the soils at both study sites.Nevertheless,the clay mineralogical composition of the soils was a mixture of kaolinite,irregularly interstratified smectite-illite intergrades (S/I),hydroxyl-Al interlayered 2:1 type clays (HICs),vermiculite,smectite,halloysite and illite along with fine-sized quartz in Abakaliki.The soils of Bende predominantly contained smectite,which was partially interlayered with hydroxyl-A1 and kaolinite.It is suggested that seasonal floodwater has slowed the disintegration of weatherable clay minerals inherited from the shale,while quartz originating from the sandstone is predominant in the fine-sand fraction.Additionally,a possible soil-forming process observed at the both study sites was ferrolysls,which was indicated by a clear decreasing pattern of HICs downward in the soil profiles.The entry of S/I and vertical distribution patterns for a couple of clay minerals in the pedon suggested that the soils in Abakaliki have developed under the significant influence of aeolian dust delivered by the Harmattan.The findings might describe a site-specific deposition pattern of Harmattan dusts as well as hydromorphic soil-forming processes in the wetlands of the inland valleys.

  9. Ultrafine particle characteristics in seven industrial plants.

    Science.gov (United States)

    Elihn, Karine; Berg, Peter

    2009-07-01

    Ultrafine particles are considered as a possible cause of some of the adverse health effects caused by airborne particles. In this study, the particle characteristics were measured in seven Swedish industrial plants, with a special focus on the ultrafine particle fraction. Number concentration, size distribution, surface area concentration, and mass concentration were measured at 10 different job activities, including fettling, laser cutting, welding, smelting, core making, moulding, concreting, grinding, sieving powders, and washing machine goods. A thorough particle characterization is necessary in workplaces since it is not clear yet which choice of ultrafine particle metric is the best to measure in relation to health effects. Job activities were given a different order of rank depending on what particle metric was measured. An especially high number concentration (130 x 10(3) cm(-3)) and percentage of ultrafine particles (96%) were found at fettling of aluminium, whereas the highest surface area concentration (up to 3800 mum(2) cm(-3)) as well as high PM10 (up to 1 mg m(-3)) and PM1 (up to 0.8 mg m(-3)) were found at welding and laser cutting of steel. The smallest geometric mean diameter (22 nm) was found at core making (geometric standard deviation: 1.9). PMID:19447849

  10. Particle Size Estimation Based on Edge Density

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-xing

    2005-01-01

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

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

    Directory of Open Access Journals (Sweden)

    S. Pfeifer

    2015-11-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  13. Measurement of nonvolatile particle number size distribution

    Science.gov (United States)

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

    2016-01-01

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

  14. Particle size distributions in the Eastern Mediterranean troposphere

    Science.gov (United States)

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

    2008-11-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Nakorn Tippayawong

    2008-03-01

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

  17. A system for aerodynamically sizing ultrafine environmental radioactive particles

    International Nuclear Information System (INIS)

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

  18. 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.

  19. Photographic techniques for characterizing streambed particle sizes

    Science.gov (United States)

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

    2003-01-01

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

  20. Langevin granulometry of the particle size distribution

    Science.gov (United States)

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

    2004-06-01

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

  1. Resonance scattering characteristics of double-layer spherical particles

    Institute of Scientific and Technical Information of China (English)

    Xuejin Dong; Mingxu Su; Xiaoshu Cai

    2012-01-01

    Based on the principle of ultrasonic resonance scattering,sound-scattering characteristics of double-layer spherical particles in water were numerically studied in this paper.By solving the equations of the scattering matrix,the scattering coefficient determined by the boundary conditions can be obtained,thus the expression for the sound-scattering function of a single double-layer spherical particle can be derived.To describe the resonance scattering characteristics of a single particle,the reduced scattering cross section and reduced extinction cross section curves were found through numerical calculation.Similarly,the numerically calculated sound attenuation coefficient curves were used to depict the resonance scattering characteristics of monodisperse and polydisperse particles.The results of numerical calculation showed that,for monodisperse particles,the strength of the resonance was mainly related to the particle size and the total number of particles; while for polydisperse particles,it was primarily affected by the particle size,the coverage of the particle size distribution and the particle concentration.

  2. Chaotic mixing of finite-sized particles

    Science.gov (United States)

    Omurtag, Ahmet Can

    1997-10-01

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

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

    International Nuclear Information System (INIS)

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

  4. DUAL-CHANNEL PARTICLE SIZE AND SHAPE ANALYZER

    Institute of Scientific and Technical Information of China (English)

    Arjen van der Schoot

    2004-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    Lijun Xu; Chang Liu; Zhang Cao; Xiaomin Li

    2013-01-01

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

  6. Particle size of spray-dried soymilk

    International Nuclear Information System (INIS)

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

  7. Particle Size Distribution and Characterization of High Siliceous and Microporous Materials

    Institute of Scientific and Technical Information of China (English)

    S.K. Durrani; J.Akhtar; M. Ahmad; M.J. Moughal

    2005-01-01

    Particle size, textural and surface characteristics influence some major technological properties of high siliceous aluminosilicate zeolite and sillicoaluminophosphate (SAPO) microporous materials. A comparative study was furnished for measuring surface characteristics, particle size and particle size distribution using particle size analyzer (PSA)and scanning electron microscope (SEM). The PSA is capable of measuring particle diameter in micron range. The results of these techniques for estimation of particle size were compared and correlated statistically. Student t-test and variance ratio test (F-test) methods were performed for the significance of results by the analysis of variance (ANONA) and multiple-range tests. Textural and surface characteristics were evaluated by Brunauer, Emmett &Teller (BET) volumetric technique and v-αs plotting method. The textural results shows that the external surface area and micropore volume of microporous materials were higher than those of the high siliceous zeolites and its zeotype materials.

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

    International Nuclear Information System (INIS)

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

  9. Particle size dependent rheological property in magnetic fluid

    Science.gov (United States)

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

    2016-06-01

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

  10. Burning characteristics of individual aluminum/aluminum oxide particles

    OpenAIRE

    Ruttenberg, Eric C.

    1996-01-01

    Approved for public release; distribution is unlimited An experimental investigation was conducted in which the burning characteristics of individual aluminum/aluminum oxide particles were measured using a windowed combustion bomb at atmospheric pressure and under gravity-fall conditions. A scanning electron microscope (SEM) was used to measure the size distribution of the initial aluminum particles and the aluminum oxide residue. Analysis of the residue indicated that the mass of aluminum...

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Czech Academy of Sciences Publication Activity Database

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

    2016-01-01

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

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

    International Nuclear Information System (INIS)

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

  14. Fractal and Morphological Characteristics of Single Marble Particle Crushing in Uniaxial Compression Tests

    OpenAIRE

    Yidong Wang; Wenjiao Dan; Yongfu Xu; Yue Xi

    2015-01-01

    Crushing of rock particles is a phenomenon commonly encountered in geotechnical engineering practice. It is however difficult to study the crushing of rock particles using classical theory because the physical structure of the particles is complex and irregular. This paper aims at evaluating fractal and morphological characteristics of single rock particle. A large number of particle crushing tests are conducted on single rock particle. The force-displacement curves and the particle size dist...

  15. Nano-sized Y2O3:Eu phosphor particles prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Y2O3:Eu phosphor particles with nano-sized and non-aggregation characteristics were prepared by spray pyrolysis using spraying solution containing polymeric precursors and Li2CO3 flux material. The post-treated phosphor particles with fine size and high brightness were ball milled to reduce the aggregation degree of the nano-sized Y2O3:Eu phosphor particles. The mean particle size, morphology, and brightness of Y2O3:Eu phosphor particles were strongly affected by contents of the additives and post-treatment temperature. The Y2O3:Eu phosphor particles prepared from the solution containing 0.3 M citric acid, 0.3 M ethylene glycol and 5 wt.% Li2CO3 had fine size and good morphology after post-treatment. The Y2O3:Eu phosphor particles post-treated at 1000 deg. C for 3 h had the mean size of 300 nm. Nano-sized Y2O3:Eu phosphor particles prepared by spray pyrolysis had similar photoluminescence intensity to the micron-sized Y2O3:Eu commercial product prepared by solid state reaction method. The Y2O3:Eu phosphor particles had aggregation-free and regular morphology characteristics even after 30 min ball milling process

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

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

    HE Gui-chun; NI Wen

    2006-01-01

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

  18. Counting and measuring particles sized from soot to pollen

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

  19. [Mineral Spectrum Change Analysis under the Conditions of Different Particle Size].

    Science.gov (United States)

    Wang, Yan-xia; Wu, Jian; Zhou, Liang-guang; Hou, Lan-gong; Wang, Dong; Cao, Min

    2015-03-01

    Mineral particle size is an important factor affecting mineral spectrum characteristics, so to explore the changes of the mineral spectrum curves under different particle sizes and the spectrum difference of different minerals under the same particle size are the keys of hyperspectral remote sensing information mineral identification and the theoretical basis of research on spectral differences of different particle -sizes. Six kinds of collected minerals were observed by spectrometer to get the reflectivity spectrum curve and first order differential spectral curve under different particle sizes, and the spectral characteristics of various kinds of minerals under different particle sizes were analyzed. At the same time, spectrum difference of different mineral under the same particle size was compared to explore possible wavelengths of hyperspectral remote sensing mineral identify. Results show that the spectrum curves of various minerals have a larger difference with the change of the particle size, but change law is not the same. The whole spectrum curve of hypersthene will be decreased with the increase of particle size, and the spectrum curve at a specific wavelength range of antigorite, hematite, kaolinite and chlorite will be decreased with the increase of particle size, and there is no direct correlation between the spectrum of olivine and the particle size. Under the same size, different mineral spectral reflectance change a lot in most band range and it provides the possibility for high precision identification of mineral. Antigorite, kaolinite and chlorite all have more absorption peaks of narrow width and smaller intensity than the other minerals. Spectrum curves of hematite, olivine and hypersthene are relatively smooth, and the number of the absorption and reflection peaks is relatively small. This study aims at providing basic data and theoretical support for mineral spectral library construction and mineral hyperspectral identification technology

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

    International Nuclear Information System (INIS)

    Growth characteristics of silica particles have been studied experimentally using in situ particle sampling technique from H2/O2/Tetraethylorthosilicate (TEOS) diffusion flame with carefully devised sampling probe. The particle morphology and the size comparisons are made between the particles sampled by the local thermophoretic method from the inside of the flame and by the electrostatic collector sampling method after the dilution sampling probe. The Transmission Electron Microscope (TEM) image processed data of these two sampling techniques are compared with Scanning Mobility Particle Sizer (SMPS) measurement. TEM image analysis of two sampling methods showed a good agreement with SMPS measurement. The effects of flame conditions and TEOS flow rates on silica particle size distributions are also investigated using the new particle dilution sampling probe. It is found that the particle size distribution characteristics and morphology are mostly governed by the coagulation process and sintering process in the flame. As the flame temperature increases, the effect of coalescence or sintering becomes an important particle growth mechanism which reduces the coagulation process. However, if the flame temperature is not high enough to sinter the aggregated particles then the coagulation process is a dominant particle growth mechanism. In a certain flame condition a secondary particle formation is observed which results in a bimodal particle size distribution

  1. Dependence of strength on particle size in graphite

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2008-01-01

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

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

    Science.gov (United States)

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

    2015-09-01

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

  4. Universal size/shape-dependent law for characteristic temperatures

    International Nuclear Information System (INIS)

    The description of different effects observed in nature by only one general equation is the 'Holy Grail' for all physicists. This goal has been achieved for characteristic temperatures through a top-down approach and is presented here. The general equation is based only on the surface area to volume ratio of nanostructures and statistics (Fermi-Dirac or Bose-Einstein) followed by the particles involved in the considered phenomena (melting, ferromagnetism, vibration and superconduction). From the distinction between fermions and bosons, this equation indicates the universal behaviour of size and shape effects. Theoretical predictions show satisfactory agreement with experimental data taken from literature.

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

    Science.gov (United States)

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

    2011-02-28

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

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

    Science.gov (United States)

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

    2005-10-15

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

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

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

    YAN Zongling; QIU Xiande; YU Yongqiang

    2003-01-01

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

  9. Study of vibration packing characteristics with simulated fuel particles

    International Nuclear Information System (INIS)

    This report presents the results of vibration packing experiments and computational simulations of particle compaction behavior. Both sphere and shard particles were evaluated in these works. Experiments with simulated fuel particles were conducted to investigate the factors affecting packing behavior. The factors are classified into geometrical and dynamics factors. With regard to the geometrical factors for sphere packing, the experimental results proved that the achievable packing fraction can be predicted by the equation derived by Ayer, which is relationship of inner diameter of cladding and diameters of particles. As for the dynamics factors, less vibration displacement is preferable, because it produces faster packing with less segregation. Similar experiments were conducted for the shard particles. The results indicate the packing characteristics of the shard particles are different from those of the sphere particles. Optimum weight ratio between particle sizes is different from the ratio given by Ayer's equation. As for the dynamics factors, the sweeping frequencies while packing were sufficient to obtain high packing fraction. Computational simulations were performed to investigate the particle behavior during packing. The movement of infiltrating and bed particles during packing was well understood. (author)

  10. 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

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

    Institute of Scientific and Technical Information of China (English)

    Hong Tang; Xiaogang Sun; Guibin Yuan

    2007-01-01

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

  12. Particle size distribution in ferrofluid macro-clusters

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-15

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

  13. Particle size distribution in ferrofluid macro-clusters

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

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

    2014-01-01

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

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

    Science.gov (United States)

    Laceby, J. Patrick; Evrard, Olivier

    2016-04-01

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

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

    Science.gov (United States)

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

  17. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-31

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

  19. 喷动床颗粒粒径对提升管团聚特性影响的三维数值研究%A 3D numerical simulation on effect of spouted bed particle size on the riser particle agglomeratione characteristics

    Institute of Scientific and Technical Information of China (English)

    周云龙; 杨宁

    2014-01-01

    The discrete element method (DEM)was used to simulate the dense gas-solid two-phase flow in a spouted bed riser pipe.The particle phase was based upon the Lagrange method,which considers the in-teraction between particle and gas phase,and the particle collision adopt the soft ball model.The gas phase was based upon eulerian method,using the standard k-ε model to simulate the gas phase turbulent flow. Through analyzing the flow behavior of particle/gas phase,the distribution of dense particles was de-scribed.Thus,the influence of particle size on particle agglomeration characteristics was studied.The re-sults indicated that when the particle size was small,a large scale agglomeration near the wall was ob-served,coupled with a bad-distributed particle flow.As the particle size increases,the agglomeration was improved considerably.When the particle size was 1 60 μm,particles distributed well along the height direc-tion,without agglomeration.The numerical simulation results agreed well with that obtained from the sub-region method.%采用离散单元方法(DEM),对喷动床提升管内稠密气固两相流动过程进行了三维数值模拟。颗粒相采用拉格朗日法,考虑了颗粒间及颗粒与气相间的相互作用,颗粒碰撞采用软球模型;气相采用欧拉法,利用标准 k-ε模型模拟气相的湍流流动。通过对颗粒和气体流动行为的分析,获得了提升管内部稠密颗粒相的分布,并考察了颗粒粒径对提升管颗粒团聚特性的影响。结果表明,当颗粒的粒径较小时,提升管壁面处发生大规模的颗粒团聚,颗粒的分布不均匀;随着颗粒粒径的增大,颗粒团聚现象得到明显改善;当颗粒粒径为160μm 时,沿着提升管高度方向的颗粒分布比较均匀,无团聚现象。通过计算分区的方法统计提升管内各区域颗粒数量百分比,统计结果与数值模拟结果吻合较好。

  20. Urban sediment particle size and pollutants in Southern Brazil

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-08-15

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

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

    DEFF Research Database (Denmark)

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

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

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

    Indian Academy of Sciences (India)

    C N Tharamani; H C Thejaswini; S Sampath

    2008-06-01

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

  3. Stability and size of particle pairs in complex plasmas

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-15

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

  4. Do finite size neutrally buoyant particles cluster?

    CERN Document Server

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

    2012-01-01

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

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

    Science.gov (United States)

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

    1999-11-01

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

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

    International Nuclear Information System (INIS)

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

  7. 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.

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

    OpenAIRE

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

    2009-01-01

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

  9. Pressure characteristics of a hydrocyclone for fine particle separation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li-xin; JIANG Ming-hu; SUN De-zhi; BELAIDI A; THEW M

    2006-01-01

    Solid-liquid hydrocyclones are mainly used to separate large particles, such as the particles of drilling fluid in petroleum industry, and large mineral particles. Till now the hydrocyclonic separation for fine particles is still a big problem. Basic separation principle of hydrocyclones and experimental research facility are simply introduced. The difficulty of separating fine particle is analyzed. Based on a solid-liquid hydrocyclone used for separating fine particles, relationships of dimensionless pressure characteristic parameters, i.e. Euler number and pressure drop ratio, with several main dimensionless parameters, such as split ratio, swirl number and gas-liquid ratio, were experimentally studied in detail. The research was carried out by using the hydrocyclonic separation experimental rig at the University of Bradford. It is shown that the less the size of particle, the less the value of radius of the balance orbit occupied by the particle, and then the more difficult for the particle to be separated. Experiments indicate that Euler number of the tested hydrocyclone increases with the rise of Reynolds number, split ratio, swirl number and gas-liquid ratio respectively, and the pressure drop ratio falls with the increase of Reynolds number, split ratio and swirl number respectively. It is concluded that the most effective way to decrease the unit energy dissipation of hydrocyclone is to reduce swirl number or gas-liquid ratio of the mixed media.

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

  12. HNF/HTPB propellants: Influence of HNF particle size on ballistic properties

    NARCIS (Netherlands)

    Heijden, A.E.D.M. van der; Leeuwenburgh, A.B.

    2009-01-01

    The burning rate characteristics of solid composite propellants can be modified via different methods. One of these is the application of different oxidizer particle sizes in the propellant. The effect of the use of fine and coarse particles of the oxidizer hydrazinium nitroformate (HNF) in hydroxyl

  13. Generation of Fine Particles with Specified Characteristics

    CERN Document Server

    Ishmatov, A N; Trubnikov, A A; Ogorodnikov, S P

    2013-01-01

    The research is devoted to the generation of fine particles and droplet flows with specified characteristics for a wide range of scientific problems. The aspects of aerodynamic fine atomization and the effects of atomizing gas density, gas velocity and mass flow rate, and liquid film thickness on the droplet formation are investigated. The hypothesis of highly efficient utilization of secondary droplets from a coarse polydisperse flow to produce fine particles is suggested and experimentally confirmed. A prototype device to implement the idea of separating the desired droplets fraction from a primary polydisperse flow was developed. In the case of fine liquid atomization, the developed spraying system enabled an increase in the gas-droplet flow concentration. The possibility of producing particles with different dispersiveness and morphology by employing the methods of spray separation and dilute solution atomization is demonstrated. The criteria of the system settings to generate the droplet flow with specif...

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

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

    舒远杰; 刘世俊; 董海山; 郝莹; 詹春红; 陈捷

    2003-01-01

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

  16. Particle size and shape distributions of hammer milled pine

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-01

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

  17. Particle size measurement in intravenous fluids.

    Science.gov (United States)

    Haines-Nutt, R F; Munton, T J

    1984-08-01

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

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  19. Sonochemical synthesis of silica particles and their size control

    Science.gov (United States)

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

    2016-09-01

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

  20. 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.

  1. Effect of Particle Size on Microstructure and Cold Compaction of Gas-Atomized Hypereutectic Al-Si Alloy Powder

    Science.gov (United States)

    Cai, Zhiyong; Wang, Richu; Peng, Chaoqun; Zhang, Chun

    2015-04-01

    The effect of particle size on the cold compaction behavior of rapidly solidified hypereutectic Al-27 wt pct Si alloy powder was studied by double action axial pressing at room temperature. The geometrical characteristics (morphology, size, shape, and distribution of Si reinforcing phase) and hardness of the powder as a function of the particle size were investigated. The result shows that finer powder particle size showed smaller primary Si particles and achieved a lower density at a given pressure. Whereas, the microhardness of Al matrix increases while the particle size decreases, which indicates that the supersaturation due to the high solidification rate increases the deformation resistance of the alloy powder. Furthermore, the geometrical characteristics of Si phases strongly depend on the particle size due to the suppressed growth of Si phases during atomization. This microstructural characteristic evidently affects the powder compactibility at high applied pressures.

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

    Science.gov (United States)

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

    2016-01-01

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

  3. The influence of particle size on the chemistry of mica clays

    OpenAIRE

    Gassman, Paul Lawrence

    1990-01-01

    In order to assess the importance of particle size on elemental composition, structure, morphology, and charge characteristics of 2:1 micas, mechanically produced clay separates were analyzed by; electron probe microanalysis (EPMA), transmission electron microscopy (TEM), thermogravimetry, specific surface area analysis, and ion exchange. Books of biotite and muscovite were reduced to clay size « 2.0 μm) particles by mechanical comminution, then further fractionated into coar...

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

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

    Science.gov (United States)

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

    2004-02-01

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

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  7. CALCULATION OF PARTICLE SIZE OF TITANIUM DIOXIDE HYDROSOL

    Directory of Open Access Journals (Sweden)

    L. M. Sliapniova

    2014-01-01

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

  8. Biofilm effects on size gradation, drag coefficient and settling velocity of sediment particles

    Institute of Scientific and Technical Information of China (English)

    Qian-qian SHANG; Hong-wei FANG; Hui-ming ZHAO; Guo-jian HE; Zheng-hui CUI

    2014-01-01

    Sediment particles are often colonized by biofilm in a natural aquatic ecological system, especially in eutrophic water body. A series of laboratory experiments on particle size gradation, drag coefficient and settling velocity were conducted after natural sediment was colonized by biofilm for 5, 10, 15 and 20 days. Particle image acquisition, particle tracking techniques of Particle Image Velocimetry and Particle Tracking Velocimetry were utilized to analyze the changes of these properties. The experimental results indicate that the size gradation, the drag force exerted on bio-particles, and the settling velocity of bio-particles underwent significant change due to the growth of biofilm onto the sediment surface. The study proposes a characteristic particle size formula and a bio-particle settling velocity formula based on the regression of experiment results, that the settling velocity is only 50% to 60%as the single particle which has the same diameter and density. However, biofilm growth causes large particle which the settling velocities are approximately 10 times larger than that of primary particles. These results may be specifically used in the low energy reservoir or lake environment.

  9. Particle size distribution in the tilapia Recirculating Aquaculture System

    OpenAIRE

    Stokic, Jelena

    2012-01-01

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

  10. Synthesis and optical properties of quantum-size metal sulfide particles in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Nedeljkovic, J.M.; Patel, R.C.; Kaufman, P.; Joyce-Pruden, C.; O' Leary, N. (Clarkson Univ., Potsdam, NY (United States))

    1993-04-01

    During the past decade, small-particle' research has become quite popular in various fields of chemistry and physics. The recognition of quantum-size effects in very small colloidal particles has led to renewed interest in this area. Small particles' are clusters of atoms or molecules ranging in size from 1 nm to almost 10 nm or having agglomeration numbers from 10 up to a few hundred. In other words, small particles fall in size between single atoms or molecules and bulk materials. The agglomeration number specifies the number of individual atoms or molecules in a given cluster. The research in this area is interdisciplinary, and it links colloidal science and molecular chemistry. The symbiosis of these two areas of research has revealed some intriguing characteristics of small particles. This experiment illustrates the following: simple colloidal techniques for the preparation of two different types of quantum-size metal sulfide particles; the blue shift of the measured optical absorption spectra when the particle size is decreased in the quantum-size regime; and use of a simple quantum mechanical model to calculate the particle size from the absorption onset measured for CdS.

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

    Institute of Scientific and Technical Information of China (English)

    曹维良; 王泽; 张敬畅

    2003-01-01

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

  12. Experimental analysis of particle sizes for PIV measurements

    Science.gov (United States)

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

    2016-09-01

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

  13. Effect of Cobalt Particle Size on Acetone Steam Reforming

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-11

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

  14. Effect of synthesis conditions on particle size of HMS

    Institute of Scientific and Technical Information of China (English)

    LI Hao; LIU Hong; HE Shi-qiang

    2009-01-01

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

  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, but...... their low spatial resolution limits their validity ranges for the coefficients. To cover a wider range of coefficients, we use camera-based spectroscopic oblique incidence reflectometry. We develop a noninvasive technique for acquisition of apparent particle size distributions based on this approach....... Our technique is validated using stable oil-in-water emulsions with a wide range of known particle size distributions. We also measure the apparent particle size distributions of complex dairy products. These results show that our tool, in contrast to those based on fiber probes, can deal with a range...

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

    OpenAIRE

    Inam, Muhammad Asif; Frances, Christine

    2010-01-01

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

  17. Particle size dependent magnetic properties and phase transitions in multiferroic BiFeO{sub 3} nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Annapu Reddy, V., E-mail: reddydph@iitr.ernet.in [Ferroelectric Materials and Devices Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand 247667 (India); Radio Frequency Integrated Circuits Research Laboratory, Department of Electronics and Computer Engineering, Indian Institute of Technology Roorkee, Uttarakhand 247667 (India); Pathak, N.P. [Radio Frequency Integrated Circuits Research Laboratory, Department of Electronics and Computer Engineering, Indian Institute of Technology Roorkee, Uttarakhand 247667 (India); Nath, R., E-mail: rnathfph@iitr.ernet.in [Ferroelectric Materials and Devices Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand 247667 (India)

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer Nano-particles of Bismuth ferrite was synthesized by spray pyrolysis technique at low temperature. Black-Right-Pointing-Pointer Bismuth ferrite exhibits room temperature weak ferromagnetism. Black-Right-Pointing-Pointer The adsorbate induced spin polarization screening in Bismuth ferrite nanoparticles. Black-Right-Pointing-Pointer The superparaelectric size of Bismuth ferrite was determined. Black-Right-Pointing-Pointer The phase transitions shift with particle size are discussed base on the modified Ising model. - Abstract: The particle size effect in the range 10-150 nm on the magnetic properties and phase transitions in BiFeO{sub 3} samples prepared by spray pyrolysis method has been studied. The phase purity and structure have been investigated by XRD and FTIR spectroscopy analysis. The FTIR peaks of the nanoparticles shift to lower wave number due to increase surface area and grain boundaries. The Fe-SEM and TEM images show that the particles are uniform, dense and of nearly spherical shape nanoparticles. The significant enhancement in magnetization with finite coercive field has been observed in 12 nm particle size samples. The increase in magnetization is about four times larger than that of the bulk samples. It has been attributed to the suppression of the cycloidal spin structure due to large uncompensated spins of Fe{sup +3} ions at the surface of the particle and the adsorbate induced spin polarization screening in BFO nanoparticles. The phase transitions above room temperature have been investigated by DTA measurements and show that Neel temperature (T{sub N}) and Curie temperature (T{sub c}) increase with particle size. The shift in T{sub N} and T{sub c} values with particle size are fitted well to the finite scaling models. The microscopic parameters like correction length, characteristic microscopic dimension of the system and critical particle size have been evaluated which provide more physical insight in

  18. Particle size dependent magnetic properties and phase transitions in multiferroic BiFeO3 nano-particles

    International Nuclear Information System (INIS)

    Highlights: ► Nano-particles of Bismuth ferrite was synthesized by spray pyrolysis technique at low temperature. ► Bismuth ferrite exhibits room temperature weak ferromagnetism. ► The adsorbate induced spin polarization screening in Bismuth ferrite nanoparticles. ► The superparaelectric size of Bismuth ferrite was determined. ► The phase transitions shift with particle size are discussed base on the modified Ising model. - Abstract: The particle size effect in the range 10–150 nm on the magnetic properties and phase transitions in BiFeO3 samples prepared by spray pyrolysis method has been studied. The phase purity and structure have been investigated by XRD and FTIR spectroscopy analysis. The FTIR peaks of the nanoparticles shift to lower wave number due to increase surface area and grain boundaries. The Fe-SEM and TEM images show that the particles are uniform, dense and of nearly spherical shape nanoparticles. The significant enhancement in magnetization with finite coercive field has been observed in 12 nm particle size samples. The increase in magnetization is about four times larger than that of the bulk samples. It has been attributed to the suppression of the cycloidal spin structure due to large uncompensated spins of Fe+3 ions at the surface of the particle and the adsorbate induced spin polarization screening in BFO nanoparticles. The phase transitions above room temperature have been investigated by DTA measurements and show that Néel temperature (TN) and Curie temperature (Tc) increase with particle size. The shift in TN and Tc values with particle size are fitted well to the finite scaling models. The microscopic parameters like correction length, characteristic microscopic dimension of the system and critical particle size have been evaluated which provide more physical insight in the finite scaling effect in the nanoparticle samples.

  19. Electrochemical characteristics of xLi2MnO3-(1-x)Li(Mn0.375Ni0.375Co0.25)O2 (0.0 ≤ x ≤ 1.0) composite cathodes: Effect of particle and Li2MnO3 domain size

    International Nuclear Information System (INIS)

    Highlights: • Average particle size of composite cathodes is varied. • Size of Li2MnO3 nano domains is a function of nominal cathode composition. • Electrochemical performances grossly depend on the size of Li2MnO3 nano domains. • Electrochemically triggered layer to spinel transformation affects cycleability. • The optimized cathode yields a discharge capacity of 300 mAhg−1 at 10 mAg−1 current. - Abstract: We have investigated the electrochemical characteristics of a series of high capacity xLi2MnO3-(1-x)Li(Mn0.375Ni0.375Co0.25)O2 (0.0 ≤ x ≤ 1.0) integrated cathodes. Among several interrelated factors (viz. nominal molar content of Li2MnO3 and Li(Mn0.375Ni0.375Co0.25)O2 constituents, activation of Li2MnO3 component, crystallinity of the particles etc) an optimum particle size is argued to be most critical to yield better electrochemical performance of the synthesized cathodes. Through X-ray diffraction in conjunction with micro-Raman spectroscopy and high resolution transmission microscopy analyses we have demonstrated that with the increase of nominal Li2MnO3 contents, the size of the ordered nano-domains (inside the active matrix) and the average size of the composite cathode particles increase systematically. The size of the ordered nano-domains, cathode particles, and electrochemically triggered layer to spinel phase transformation influence the electrochemical characteristics of these cathodes. The average particle size of 0.5Li2MnO3- 0.5Li(Mn0.375Ni0.375Co0.25)O2 particles have been systematically varied by tuning the calcination time temperature combination. The optimized cathode yields a discharge capacity ∼ 300 mAhg−1 with capacity retention about 96% after 50 charge-discharge cycles at 10 mAg−1 rate. The cathode with optimal particle size also exhibits a decent rate capability with room temperature discharge capacity ∼ 200 mAhg−1 at 300 mAg−1 rate

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

    Science.gov (United States)

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

    2016-08-01

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

  1. Laboratory and field evaluations of the LISST-100 instrument for suspended particle size determinations

    Science.gov (United States)

    Gartner, J.W.; Cheng, R.T.; Wang, P.-F.; Richter, K.

    2001-01-01

    Advances in technology have resulted in a new instrument that is designed for in-situ determination of particle size spectra. Such an instrument that can measure undisturbed particle size distributions is much needed for sediment transport studies. The LISST-100 (Laser In-Situ Scattering and Transmissometry) uses the principle of laser diffraction to obtain the size distribution and volume concentration of suspended material in 32 size classes logarithmically spaced between 1.25 and 250 ??m. This paper describes a laboratory evaluation of the ability of LISST-100 to determine particle sizes using suspensions of single size, artificial particles. Findings show the instrument is able to determine particle size to within about 10% with increasing error as particle size increases. The instrument determines volume (or mass) concentration using a volume conversion factor Cv. This volume conversion factor is theoretically a constant. In the laboratory evaluation Cv is found to vary by a factor of about three over the particle size range between 5 and 200 ??m. Results from field studies in South San Francisco Bay show that values of mass concentration of suspended marine sediments estimated by LISST-100 agree favorably with estimates from optical backscatterance sensors if an appropriate value of Cv, according to mean size, is used and the assumed average particle (aggregate) density is carefully chosen. Analyses of size distribution of suspended materials in South San Francisco Bay over multiple tide cycles suggest the likelihood of different sources of sediment because of different size characteristics during flood and ebb cycles. ?? 2001 Elsevier Science B.V.

  2. FRACTIONATION OF PULP AND PAPER PARTICLES SELECTIVELY BY SIZE

    Directory of Open Access Journals (Sweden)

    Ossi Tapio Laitinen

    2011-02-01

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

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

    Science.gov (United States)

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

    2008-11-01

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

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

    International Nuclear Information System (INIS)

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

  5. Prediction of Particle Size of Ammonium Perchlorate during Pulverisation

    Directory of Open Access Journals (Sweden)

    Sunil Jain

    2006-07-01

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

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

    International Nuclear Information System (INIS)

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

  7. Measurement of particle size based on digital imaging technique

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

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

  8. Size distribution of particle systems analyzed with organic photodetectors

    CERN Document Server

    Sentis, Matthias

    2015-01-01

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

  9. Characteristics of the fine particles generated in plasma process

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, A.; Matsubayashi, K.; Susuki, M. [Tokyo Institute of Technology, Graduate School of Science and Engineering (Japan)

    2001-07-01

    Modeling of fine particles generation in plasma process under an atmospheric pressure is investigated. Our model consists of two physical phenomena, evaporation of metal and particle growth, were studied with computer simulation. Evaporation phenomenon is simulated by lattice Boltzmann method and evaporation rate of iron is estimated. Particle growth is simulated by using general dynamic equation. Agglomerate consisting of primary particles which is taken size distribution into account is represented by fractal dimension connecting number density of primary particles. Particle size and particle size distribution at various temperatures are obtained and discussed. (authors)

  10. RNA Control of HIV-1 Particle Size Polydispersity

    CERN Document Server

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2016-04-19

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

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

    Science.gov (United States)

    Mao, Jiandong; Li, Jinxuan

    2015-10-01

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

  13. Studies on the particle size control of gelatin microspheres

    Institute of Scientific and Technical Information of China (English)

    Ruixue SUN; Jingjing SHI; Yanchuan GUO; Lijuan CHEN

    2009-01-01

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

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

    International Nuclear Information System (INIS)

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

  15. Componentes de rendimento e características da carne e carcaça de novilhos confinados sob efeito do tamanho de partícula e da altura de colheita das plantas de milho na ensilagem Yield composition and characteristics of meat and carcass of steers confineds on effect of particle size and cutting height of corn plant for silage

    Directory of Open Access Journals (Sweden)

    Mikael Neumann

    2008-04-01

    Full Text Available O experimento foi conduzido no Núcleo de Produção Animal (NUPRAN da Universidade Estadual do Centro Oeste do Paraná (UNICENTRO com o objetivo de avaliar o efeito do tamanho de partícula (pequena: entre 0,2 e 0,6cm ou grande: entre 1,0 e 2,0cm e da altura de corte das plantas de milho para ensilagem (baixa: 15cm, ou alta: 39cm, sobre os componentes de rendimento e as características da carne e carcaça de novilhos terminados em confinamento, constituindo-se os tratamentos: T1 - silagem de partícula pequena com altura de corte baixa; T2 - silagem de partícula grande com altura de corte baixa; T3 - silagem de partícula pequena com altura de corte alta; e T4 - silagem de partícula grande com altura de corte alta. Não houve interação significativa (P>0,05 entre altura de colheita e tamanho de partícula para os parâmetros relativos aos componentes de rendimento e às características da carne e carcaça. Silagens de partícula pequena na dieta alimentar de bovinos confinados proporcionaram maior (P0,05 nas características da carcaça, na qualidade da carne e nos componentes de rendimento da carcaça na produção de novilhos de corte confinados.The experiment was conducted at the Núcleo de Produção Animal (NUPRAN of Universidade Estadual do Centro Oeste do Paraná (UNICENTRO. The experiment was aimed at evaluating the composition of yield and characteristics of meat and carcass on effect of particle sizes (small: between 0.2 and 0.6cm or large: between 1.0 and 2.0cm and cutting heights (low cut: 15cm or high cut: 39cm of the corn plant. The treatments were: T1 - small particle size with low cut height; T2 - large particle size with low cut height; T3 - small particle size with high cut height; and T4 - large particle size with high cut height. No signification interaction (P>.05 was observed between cutting height and particle size for composition of income and characteristics of meat and carcass. Small particle silages in diet for

  16. Particle size distribution and pollutants in road-deposited sediments in different areas of Zhenjiang, China.

    Science.gov (United States)

    Bian, Bo; Zhu, Wei

    2009-08-01

    An understanding of road-deposited sediment (RDS) characteristics on an impervious surface is essential to estimate pollutant washoff characteristics and to minimise the impacts of pollutants on the water environment. A total of 62 RDS samples were collected from four different land-use types (commercial, residential, intense traffic and riverside park) in Zhenjiang City, China. The samples were fractionated into seven grain-size classes and analysed for particle size distribution and concentrations of pollutants. The samples are found to consist predominantly of fine particles (60-80%, traffic area. The maximum mean contents of organic matter (12.55%), nitrogen (6.31 mg/g) and phosphorus (5.15 mg/g) were found in samples from the commercial area. The concentrations of heavy metals were highest in the smallest particle size fraction analysed (63 microm). The organic matter and nitrogen content generally increased with decreasing particle sizes in the <500-microm particle size range. The results also revealed that most of the total nitrogen (TN) is attached to the finer sediments and that to effectively reduce TN loads in particulates, treatment facilities must be able to remove the finer particles (down to 125 microm for TN). PMID:18791663

  17. Characteristics of aerosolized ice forming marine biogenic particles

    Science.gov (United States)

    Alpert, Peter A.

    Ice particles are ubiquitous in the atmosphere existing as the sole constituents of glaciated cirrus clouds or coexisting with supercooled liquid droplets in mixed-phase clouds. Aerosol particles serving as heterogeneous ice nuclei for ice crystal formation impact the global radiative balance by modification of cloud radiative properties, and thus climate. Atmospheric ice formation is not a well understood process and represents great uncertainty for climate prediction. The oceans which cover the majority of the earth's surface host nearly half the total global primary productivity and contribute to the greatest aerosol production by mass. However, the effect of biological activity on particle aerosolization, particle composition, and ice nucleation is not well established. This dissertation investigates the link between marine biological activity, aerosol particle production, physical/chemical particle characteristics, and ice nucleation under controlled laboratory conditions. Dry and humidified aerosol size distributions of particles from bursting bubbles generated by plunging water jets and aeration through frits in a seawater mesocosm containing bacteria and/or phytoplankton cultures, were measured as a function of biological activity. Total particle production significantly increases primarily due to enhanced aerosolization of particles ≤100 nm in diameter attributable to the presence and growth of phytoplankton. Furthermore, hygroscopicity measurements indicate primary organic material associated with the sea salt particles, providing additional evidence for the importance of marine biological activity for ocean derived aerosol composition. Ice nucleation experiments show that these organic rich particles nucleate ice efficiently in the immersion and deposition modes, which underscores their importance in mixed-phase and cirrus cloud formation processes. In separate ice nucleation experiments employing pure cultures of Thalassiosira pseudonana, Nannochloris

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

    Science.gov (United States)

    Burgess, D J; Singh, O N

    1993-07-01

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

  19. Effects of childhood body size on breast cancer tumour characteristics

    OpenAIRE

    Li, Jingmei; Humphreys, Keith; Eriksson, Louise; Czene, Kamila; Liu, Jianjun; Hall, Per

    2010-01-01

    Introduction Although a role of childhood body size in postmenopausal breast cancer risk has been established, less is known about its influence on tumour characteristics. Methods We studied the relationships between childhood body size and tumour characteristics in a Swedish population-based case-control study consisting of 2,818 breast cancer cases and 3,111 controls. Our classification of childhood body size was derived from a nine-level somatotype. Relative risks were estimated by odds ra...

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Jiangfeng Shao; Jiandong Mao

    2016-01-01

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

  2. Size distribution of particle systems analyzed with organic photodetectors

    OpenAIRE

    Sentis, Matthias

    2015-01-01

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

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

    Science.gov (United States)

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

    2016-04-15

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

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

    International Nuclear Information System (INIS)

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

  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 distribution dynamics during precipitative softening: declining solution composition.

    Science.gov (United States)

    Nason, Jeffrey A; Lawler, Desmond F

    2009-02-01

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

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

    Science.gov (United States)

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

    2009-11-01

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

  8. 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.

  9. Particle characteristics and reduction behavior of synthetic magnetite

    Science.gov (United States)

    Ramadan, Wegdan; Zaki, Mohamed I.; Fouad, Nasr E.; Mekhemer, Gamal A. H.

    2014-04-01

    Two samples (S1 and S2) of magnetite were synthesized, using two different methods, and characterized by means of X-ray powder diffractometry, infrared and Mössbauer spectroscopy, N2 sorptiometry and electron microscopy. Particles of sample-S1 were found to be loosely agglomerated, micro-sized spheroids (200-350 nm) composed almost solely of highly aggregated (fused) crystallites (size averaged at 35 nm) of cubic-Fe3O4. In contrast, particles of sample-S2 were strongly agglomerated, nano-sized spheroids (25-30 nm) composed of slightly aggregated crystallites (size averaged at 11 nm) of cubic-Fe3O4 and noncrystalline domains made-up of FeO(OH) species. Temperature-programed reduction (TPR) profiles obtained for the two samples were similar in monitoring two peaks at >450 °C assignable to a two-step reduction of Fe3O4 (→FeO→Fe), but different in monitoring a peak at<450 °C only for the reduction of FeO(OH) (→Fe3O4) contained in sample-S2. However, curve fitting analysis of the TPR profiles and molecular stoichiometry calculations based on amounts of hydrogen consumed revealed that the two-step reduction of Fe3O4 is not straightforward. That is by resolving two consecutive pathways for each step and, hence, nonstoichiometric intermediate products whose composition was found to be critically controlled by the composition of the reducing gas atmosphere (5 or 80% H2/N2) and characteristics of the starting sample particles (chemical and phase composition, and, but to lesser extents, the agglomeration and average size).

  10. Dependence of CO2 absorption on particle size ferroelectric materials

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    1979-01-01

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

  12. 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.

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Science.gov (United States)

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

    2016-05-25

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

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

    Science.gov (United States)

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

    2015-04-01

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

  16. Computer Simulation of Packing of Particles with Size Distributions Produced by Fragmentation Processes

    OpenAIRE

    Martin Martin, Miguel Angel; Muñoz Ortega, Francisco Javier; Reyes Castro, Miguel E.; Taguas Coejo, Francisco Javier

    2015-01-01

    Fragmentation schemes inspired by theoretical results and conjectures of Kolmogorov are applied to produce particle size distributions of different natures, depending on fragmentation parameters. A two-dimensional computer simulation method of packing is applied to the resulting distributions and the void fraction is evaluated. The relationship between the void fraction and characteristic parameters of the fragmentation process is studied.

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

    OpenAIRE

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

    2009-01-01

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

  18. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts.

    Science.gov (United States)

    Babu, S Suresh; Kompalli, Sobhan Kumar; Moorthy, K Krishna

    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 (~15-15,000nm) 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 <100nm) 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 167nm and 1150 to 1760nm 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

  19. Particle Size Affects Concentration-Dependent Cytotoxicity of Chitosan Nanoparticles towards Mouse Hematopoietic Stem Cells

    Directory of Open Access Journals (Sweden)

    Siti Sarah Omar Zaki

    2015-01-01

    Full Text Available 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-23

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

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

    Science.gov (United States)

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

    2016-08-01

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

  2. 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...

  3. Aerosol Particle Size Distributions at a Rural Coastal Site

    NARCIS (Netherlands)

    Leeuw, G. de; Vignati, E.

    1998-01-01

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

  4. Particle size and packing characterization by diffuse light transmission

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

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

    Science.gov (United States)

    Bisschop, F. De; Segaert, O.

    1986-01-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  7. Evolution of Particle Size Distributions in Fragmentation Over Time

    Science.gov (United States)

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

    2013-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Blanco-Mantecon, M

    2000-02-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  10. Particle characteristics and reduction behavior of synthetic magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Ramadan, Wegdan [Physics Department, Faculty of Science, Alexandria University, Alexandria 21511 (Egypt); Zaki, Mohamed I., E-mail: mizaki@link.net [Chemistry Department, Faculty of Science, Minia University, El-Minia 61519 (Egypt); Fouad, Nasr E.; Mekhemer, Gamal A.H. [Chemistry Department, Faculty of Science, Minia University, El-Minia 61519 (Egypt)

    2014-04-15

    Two samples (S1 and S2) of magnetite were synthesized, using two different methods, and characterized by means of X-ray powder diffractometry, infrared and Mössbauer spectroscopy, N{sub 2} sorptiometry and electron microscopy. Particles of sample-S1 were found to be loosely agglomerated, micro-sized spheroids (200–350 nm) composed almost solely of highly aggregated (fused) crystallites (size averaged at 35 nm) of cubic-Fe{sub 3}O{sub 4}. In contrast, particles of sample-S2 were strongly agglomerated, nano-sized spheroids (25–30 nm) composed of slightly aggregated crystallites (size averaged at 11 nm) of cubic-Fe{sub 3}O{sub 4} and noncrystalline domains made-up of FeO(OH) species. Temperature-programed reduction (TPR) profiles obtained for the two samples were similar in monitoring two peaks at >450 °C assignable to a two-step reduction of Fe{sub 3}O{sub 4} (→FeO→Fe), but different in monitoring a peak at<450 °C only for the reduction of FeO(OH) (→Fe{sub 3}O{sub 4}) contained in sample-S2. However, curve fitting analysis of the TPR profiles and molecular stoichiometry calculations based on amounts of hydrogen consumed revealed that the two-step reduction of Fe{sub 3}O{sub 4} is not straightforward. That is by resolving two consecutive pathways for each step and, hence, nonstoichiometric intermediate products whose composition was found to be critically controlled by the composition of the reducing gas atmosphere (5 or 80% H{sub 2}/N{sub 2}) and characteristics of the starting sample particles (chemical and phase composition, and, but to lesser extents, the agglomeration and average size). - Highlights: • Nano or micro, pure Fe{sub 3}O{sub 4} particles are H{sub 2}-reduced in two steps (→FeO→Fe) at >450 °C. • FeO(OH)-impure particles exhibit a third reduction step (FeO(OH)→Fe{sub 3}O{sub 4}) at <450 °C. • FeO disproportion and related autocatalytic effects complicate the reduction course. • Consequently, each of the Fe{sub 3}O{sub 4

  11. Ultrasonic cavitation for obtainment of nanometric sized particles

    Science.gov (United States)

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

    2016-02-01

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

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

    International Nuclear Information System (INIS)

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

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

    Czech Academy of Sciences Publication Activity Database

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

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

  14. 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 ...

  15. Feed preference in pigs: relationship with feed particle size and texture.

    Science.gov (United States)

    Solà-Oriol, D; Roura, E; Torrallardona, D

    2009-02-01

    In previous studies, we observed important differences in the feed preferences of pigs resulting from changes in only 1 dietary ingredient. The present experiment was conducted to study the relationship between the feed preference values of feeds reported previously and their particle size and texture characteristics. The effect of individual feed ingredients was studied when added to a common basal diet. In addition to the basal diet, which included rice, a soybean meal product containing 56% CP, sunflower oil, and wheat bran, a total of 126 diets were studied. Of these, 63 were prepared by replacing the rice in the basal diet with another cereal, 29 by replacing the soybean product with different protein sources, 19 by replacing the sunflower oil with different lipid sources, and 6 by replacing the wheat bran with different fiber sources. Cereals were studied at inclusion rates of 150, 300, and 600 g x kg(-1); protein sources were studied at 50, 100, and 200 g x kg(-1); lipids were studied at 15, 30, and 100 g x kg(-1); and fiber sources were studied at 65 and 130 g x kg(-1). The particle size profile of all the diets was determined by using a 9-screen sieve shaker. The geometric mean particle size, particle size uniformity, number of particles per gram, surface area (cm(2) x g(-1)), and percentage of fine (passing through a 250-microm sieve) and coarse particles (remaining in a 2,000-microm sieve) were calculated. The texture properties (hardness, fragility, chewing work, and adhesiveness) of the feeds were also determined by using a texture analyzer. The Pearson correlation coefficients of these variables with feed preference were as follows: geometric mean particle size (r = 0.07; P = 0.45), particle size uniformity (r = 0.16; P = 0.07), number of particles per gram (r = -0.05; P = 0.61), surface area (r = -0.07; P = 0.46), percentage of coarse particles (r = 0.04; P = 0.65), percentage of fine particles (r = -0.12; P = 0.19), hardness (r = -0.21; P = 0

  16. [Particle Size Distribution and Pollutant Speciation Analyses of Stormwater Runoff in the Ancient Town of Suzhou].

    Science.gov (United States)

    Li, Huai; Wu, Wei; Tian, Yong-jing; Huang, Tian-yin

    2016-02-15

    The particle size distribution (PSD) and its transformation processes in the stormwater runoffs in the ancient town of Suzhou were studied based on the particles size analyses, the water-quality monitoring data and the parameters of the rainfall-runoff models. The commercial districts, the modern residential area, the old residential area, the traffic area and the landscape tourist area were selected as the five functional example areas in the ancient town of Suzhou. The effects of antecedent dry period, the rainfall intensity and the amount of runoffs on the particle size distributions were studied, and the existing forms of the main pollutants in different functional areas and their possible relations were analyzed as well. The results showed that the particle size distribution, the migration processes and the output characteristics in the stormwater runoffs were greatly different in these five functional areas, which indicated different control measures for the pollution of the runoffs should be taken in the design process. The antecedent dry period, the rainfall intensity and the amount of runoffs showed significant correlations with the particle size distribution, showing these were the important factors. The output of the particles was greatly influenced by the flow scouring in the early period of the rainfall, and the correlations between the amount of runoffs and the particle migration ability presented significant difference in 30% (early period) and 70% (later period) of the runoff volume. The major existence form of the output pollutants was particle, and the correlation analyses of different diameter particles showed that the particles smaller than 150 microm were the dominant carrier of the pollutants via adsorption and accumulation processes. PMID:27363145

  17. [Particle Size and Number Density Online Analysis for Particle Suspension with Polarization-Differentiation Elastic Light Scattering Spectroscopy].

    Science.gov (United States)

    Chen, Wei-kang; Fang, Hui

    2016-03-01

    The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products. PMID:27400522

  18. Particle rebound characteristics of turbomachinery cascade leading edge geometry

    Science.gov (United States)

    Siravuri, Sastri

    The objective of this research work is to investigate and understand the complex phenomena associated with the mechanism of particle impacts on turbomachinery cascade leading edge geometry. At present, there is a need for experimental work in basic and applied research to find out the parameters that are relevant to particle rebound characteristics on turbomachinery blades. In the present work, experiments were conducted with air velocity at 15 m/s (˜50 ft/sec) and at 30 m/s (˜100 ft/sec) using high-speed photography and Laser Doppler Velocimetry (LDV). Silica sand particles of 1000--1500 micron size were used for this study. In the present investigation, particle rebound data was obtained for cylindrical targets with radius of curvature representative of leading edge geometry (cylinder diameter = 4.5mm & 6.5 mm) using LDV. The numerical simulations, which are based on non-linear dynamic analysis, were also performed using the finite element code DYNA3-D. Several different material models viz elastic-elastic, elastic-plastic, elastic-plastic with friction & isotropic-elastic-plastic with dynamic friction and particle rotation were used in the DYNA3-D numerical analysis. The computational results include a time history of the displacement, stress and strain profiles through the particle collision. Numerical results are presented for the rebound conditions of spherical silica sand particle for different pre-collision velocities. The computed particle restitution coefficients, after they reach steady rebound conditions, are compared with experimental results obtained from LDV. A probabilistic model was developed to incorporate the uncertainties in the impact velocity in the numerical model. Histograms and Cumulative Distribution Functions (CDFs) for impact velocity were obtained from experimental LDV data. Ten randomly selected probabilities for each impact angle were used to calculate the impact velocity from cumulative distribution function. This randomly selected

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

    Science.gov (United States)

    Roberts, Jeffrey

    2005-03-01

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

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

    Science.gov (United States)

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

    2002-11-01

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

  1. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-22

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

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

    Science.gov (United States)

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

    2002-08-16

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

  4. DNA Gel Particles: Particle Preparation and Release Characteristics

    OpenAIRE

    Morán, M. Carmen; Miguel, M. Graça; Lindman, Björn

    2007-01-01

    Aqueous mixtures of oppositely charged polyelectrolytes undergo associative phase separation, resulting in coacervation, gelation, or precipitation. This phenomenon has been exploited here to form DNA gel particles by interfacial diffusion. We report the formation of DNA gel particles by mixing solutions of DNA (either single-stranded (ssDNA) or double-stranded (dsDNA)) with solutions of cationic surfactant CTAB and solutions of the protein lysozyme. Swelling, surface morphology, and DNA rele...

  5. TEMPORAL AND SPATIAL DYNAMICS OF DIFFERENT PARTICLE SIZE OF SUSPENDED SEDIMENT IN THE LIU RIVER CATCHMENTS,CHINA

    Institute of Scientific and Technical Information of China (English)

    Haoming FAN; Qiangguo CAI; Chengjiu GUO; Tieliang WANG

    2006-01-01

    This paper presents information on the particle size characteristics of suspended sediment transported by the Liu River, which has the most serious erosion and sedimentation problems in the northeast of China. The median (d50) particle size for the individual stations on the Liu River ranged from 0.0343 to 0.0588 mm. Particles <0.01 mm ranged from 15.4 to 33.3% and >0.05 mm of ranged from 24.3 to 53.7%. Spatial and temporal variations were noticeable in the particle size composition of suspended sediment within the study basins. At different locations the sediment particles size varies as a result of differences in catchment characteristics. The preferential deposition of the coarser size fractions has resulted in downstream fining of the suspended sediment load. In the flood season the suspended sediment particle size was finer than that in low flow season. The relations among water discharge, suspended sediment concentration, and sediment particle size are complicated. At small water discharge or suspended sediment concentration, with the increase of water discharge or sediment concentration the particle size of suspended sediment decreases to a minimum. However, when the water discharge or sediment concentration exceed certain threshold values (turning points) the particle size increases or remains constant with the increase of water discharge or sediment concentration. The tuning points are different in different rivers. Thus, their relations are double-valued. The negative relation between suspended sediment particle size and flow discharge reflects the importance of supply conditions and the positive relation reflects that the flow and hydraulics take a greater role in sediment transportation. On the whole, variation of the sediment particle size is subject to many factors such as the hydraulic conditions, the type and extent of erosion, human activities, vegetation coverage, hydraulic projects, and sediment supply. The findings reported in this paper

  6. On-line non-intrusive particle size measurement of pulverised fuel through digital imaging

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents the basic principles of particle size measurement and latest industrial results recorded using an innovative optical instrumentation system designed to measure the size distribution of particles in a pneumatic suspension. The system is non-intrusive and cost-effective. A low-cost CCD camera is used to capture images of the particulate flow field, which is illuminated by a low-cost pulsed laser sheet generator. The particle size distribution is then determined by processing the particle images through the use of novel processing algorithms. Experimental results obtained in the past on a small scale particle flow test rig have demonstrated that the system is capable of measuring the size distribution of pneumatically conveyed particles with an accuracy of a few percent. For the present paper results obtained when testing the system at a 4 MW industrial test facility are presented. Comparisons are made with both off-line reference data achieved through sieving and on-line laser diffraction data recorded using an intrusive, extractive, Malvern Instruments system. In general there is good agreement between results when considering the characteristics and limitations of the individual methodologies. The novel imaging system shows itself to be rugged, practical and useful under genuine industrial conditions.

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

    Science.gov (United States)

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

    2016-08-01

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

  8. Effects of aerosol particle size on dispersion and continuous air monitor response in a plutonium laboratory

    International Nuclear Information System (INIS)

    The effectiveness of continuous air monitors (CAMs) in protecting plutonium workers depends on the efficiency of aerosol transport from the release point to the CAM. The main processes for aerosol transport are diffusion, forced convection, and gravitational settling. The transport of particles relative to each of these processes depends on particle size. Studies have shown that activity median aerodynamic diameters for plutonium aerosols can range from less than 0.1 μm to greater than 10 μm. The purpose of this study was to characterize the influence of particle size on aerosol transport and CAM response in a plutonium laboratory. Polydisperse dioctyl sebacate oil aerosols were released from multiple locations within a plutonium laboratory at Los Alamos National Laboratory. An array of Laser Particle counters (LPCs) positioned in the laboratory measured time resolved aerosol dispersion. Aerosol concentrations were binned into two size ranges: (1) 0.5 μm to 5.0 μm, and (2) those greater than 5.0 μm. Statistical comparisons were done and the results suggested that transport efficiency was greater for smaller particles than larger particles in this laboratory. This result suggested the importance of using particles of similar physical characteristics to those of the source when doing tests to decide optimal placement of CAMs

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

    Science.gov (United States)

    Nason, Jeffrey A; Lawler, Desmond F

    2008-08-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

  11. Building predictive models of soil particle-size distribution

    OpenAIRE

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

    2013-01-01

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

  12. Underlying event characteristics and their dependence on jet size of charged-particle jet events in p anti-p collisions at sqrt{s}=7 TeV with the ATLAS detector

    Czech Academy of Sciences Publication Activity Database

    Aad, G.; Abbott, B.; Abdallah, J.; Böhm, Jan; Chudoba, Jiří; Gallus, Petr; Gunther, Jaroslav; Jakoubek, Tomáš; Juránek, Vojtěch; Kepka, Oldřich; Kupčo, Alexander; Kůs, Vlastimil; Lokajíček, Miloš; Marčišovský, Michal; Mikeštíková, Marcela; Myška, Miroslav; Němeček, Stanislav; Růžička, Pavel; Schovancová, Jaroslava; Šícho, Petr; Staroba, Pavel; Svatoš, Michal; Taševský, Marek; Tic, Tomáš; Valenta, J.; Vrba, Václav; Zeman, Martin

    2012-01-01

    Roč. 86, č. 7 (2012), "072004-1"-"072004-21". ISSN 1550-7998 R&D Projects: GA MŠk LA08032 Institutional research plan: CEZ:AV0Z10100502 Keywords : charged particle transverse momentum * charged particle multiplicity * underlying event * ATLAS Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 4.691, year: 2012 http:// arxiv .org/abs/ arXiv :1208.0563

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

    CERN Document Server

    Gundlach, B

    2014-01-01

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

  14. Production of large-particle-size monodisperse latexes

    Science.gov (United States)

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

    1984-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    SHAO Liming; HE Peipei; YU Guanghui; HE Pinjing

    2009-01-01

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

  16. Size dependence of vacancy migration energy in ionic nano particles: A potential energy landscape perspective

    Science.gov (United States)

    Niiyama, Tomoaki; Okushima, Teruaki; Ikeda, Kensuke S.; Shimizu, Yasushi

    2016-06-01

    Size dependence of vacancy migration energy in ionic nano particles is investigated by analysis of potential energy surfaces in potassium chloride clusters. Numerical methods are used to find almost all local minima and transition states for vacancy migration in clusters of different sizes, and reveal characteristic features of energy surface structure. It is shown that migration energy is significantly lower near a cluster surface than near a cluster core, and the mean first-passage time for migration of a vacancy decreases with cluster size. These results are consistent with observations of high diffusion rates in small clusters.

  17. Paramagnetic properties of size-controlled squid ink particles dispersed in water

    International Nuclear Information System (INIS)

    The paramagnetic properties of size-controlled ink particles isolated from the ink sacs of squid were studied by electron spin resonance (ESR). ESR spectra of the large and small ink particles dispersed in water were successfully observed at room temperature. Both the ink particles in aqueous suspensions seemingly indicated similar ESR spectra consisting of a singlet with a slightly asymmetrical signal. The linewidth below saturation was almost the same in both the ink particles, but the linewidth of the small ink particle was obviously broadened with an increase in microwave power. On the other hand, the progressive microwave power saturation revealed a clear difference between the paramagnetic behaviors of the ink particles in aqueous suspensions and in solid states. In comparison with dehydrated samples, the ESR signals of the ink particles dispersed in water showed the inhomogeneous broadening and faster spin-lattice relaxation processes. The fundamental characteristics of size-controlled ink particles would serve as basic information for various applications. (author)

  18. Aerosol size distribution seasonal characteristics measured in Tiksi, Russian Arctic

    Science.gov (United States)

    Asmi, E.; Kondratyev, V.; Brus, D.; Laurila, T.; Lihavainen, H.; Backman, J.; Vakkari, V.; Aurela, M.; Hatakka, J.; Viisanen, Y.; Uttal, T.; Ivakhov, V.; Makshtas, A.

    2016-02-01

    Four years of continuous aerosol number size distribution measurements from the Arctic Climate Observatory in Tiksi, Russia, are analyzed. Tiksi is located in a region where in situ information on aerosol particle properties has not been previously available. Particle size distributions were measured with a differential mobility particle sizer (in the diameter range of 7-500 nm) and with an aerodynamic particle sizer (in the diameter range of 0.5-10 μm). Source region effects on particle modal features and number, and mass concentrations are presented for different seasons. The monthly median total aerosol number concentration in Tiksi ranges from 184 cm-3 in November to 724 cm-3 in July, with a local maximum in March of 481 cm-3. The total mass concentration has a distinct maximum in February-March of 1.72-2.38 μg m-3 and two minimums in June (0.42 μg m-3) and in September-October (0.36-0.57 μg m-3). These seasonal cycles in number and mass concentrations are related to isolated processes and phenomena such as Arctic haze in early spring, which increases accumulation and coarse-mode numbers, and secondary particle formation in spring and summer, which affects the nucleation and Aitken mode particle concentrations. Secondary particle formation was frequently observed in Tiksi and was shown to be slightly more common in marine, in comparison to continental, air flows. Particle formation rates were the highest in spring, while the particle growth rates peaked in summer. These results suggest two different origins for secondary particles, anthropogenic pollution being the important source in spring and biogenic emissions being significant in summer. The impact of temperature-dependent natural emissions on aerosol and cloud condensation nuclei numbers was significant: the increase in both the particle mass and the CCN (cloud condensation nuclei) number with temperature was found to be higher than in any previous study done over the boreal forest region. In addition

  19. Particle Size Distribution in Saturn’s Ring C

    Science.gov (United States)

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

    2012-10-01

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

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

    International Nuclear Information System (INIS)

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

  1. Particle size analysis of prepared solutions and fingerprint deposits of high explosive materials

    Energy Technology Data Exchange (ETDEWEB)

    Carmack, W.J.; Hembree, P.B.

    1998-03-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) managed and operated by Lockheed Martin Idaho Technologies Company (LMITCO) was tasked via the Federal Aviation Administration (FAA) and US Department of Energy (DOE) to conduct various studies involving the detection and measurement of explosive materials and their associated residues. This report details the results of an investigation to determine the particle size characteristics of the explosive materials used in the design, development, and testing of trace explosives detection systems. These materials, in the form of water suspensions of plastic explosives, are used to provide a quantitative means of monitoring the performance characteristics of the detection systems. The purpose of this investigation is to provide data that allows a comparison between the particles deposited using the suspension standards and the particles deposited from fingerprints. This information may support the development of quality control aids, measurement methods, or performance criteria specifications for the use of trace explosives detection systems. For this report, particle size analyses were completed on explosives standard suspensions/solutions for composition C-4, Semtex-H, and Detasheet and fingerprints for C-4, Detasheet, and pentolite. Because of the difficulty in collecting microscopic images of the particles in the suspensions from test protocol surfaces, this paper discusses the characteristics of the particles as they are found on metal, glass, and paper. The results of the particle characterization analyses indicate that the water suspensions contain particulate composed of binder materials and dissolved portions of the explosive compounds. Upon drying of the water suspensions, significant particle nucleation and growth is observed. The nucleated particulate is comparable to the particulate deposited by fingerprints.

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

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

    Pugliese, Lorenzo; Poulsen, Tjalfe; Straface, Salvatore

    2013-01-01

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

  4. Particle size characterization using fraunhoffer diffraction and milling performance of maize

    Directory of Open Access Journals (Sweden)

    Chaurand M.

    1997-12-01

    Full Text Available Twenty-six samples of hybrid maizes (ROSSO flint maize, VOLGA dent maize, DEA and MONARQUE flint-dent maizes were dry-milled and separated into fractions. The milling yield was determined. Particle size was measured by mechanical sieving for grits, and by laser diffraction for coarse and fine semolina and flours. Bimodal particle size distributions of fine semolina and flours were analyzed as a function of mode size and proportion. Despite inherent variations in culture conditions, differences were apparent between VOLGA and the three other hybrids. The principal mode was characteristic of the fraction considered, without clear varietal differentiation. Analysis of the secondary mode of fine semolina and flours showed that it was principally due to particles similar in size to starch granules (14 to 17/*m, VOLGA particles being smaller than the others. The relative "weight" of the secondary mode was greater with VOLGA than with the three other maize types. The small differences observed between DEA and the ROSSO and MONARQUE hybrids were not significant. A technological behaviour index is proposed: the calculated quantity (g of very fine particles constituting the secondary modes of fine semolina and flours (per 1 g of ground maize. This index is inversely correlated with the yield of grits (r=0.913 for the 26 samples, and may therefore prove useful in the cultivation and processing of maize.

  5. On the time-averaging of ultrafine particle number size spectra in vehicular plumes

    Directory of Open Access Journals (Sweden)

    X. H. Yao

    2006-01-01

    Full Text Available Ultrafine vehicular particle (<100 nm number size distributions presented in the literature are mostly averages of long scan-time (~30 s or more spectra mainly due to the non-availability of commercial instruments that can measure particle distributions in the <10 nm to 100 nm range faster than 30 s even though individual researchers have built faster (1–2.5 s scanning instruments. With the introduction of the Engine Exhaust Particle Sizer (EEPS in 2004, high time-resolution (1 full 32-channel spectrum per second particle size distribution data become possible and allow atmospheric researchers to study the characteristics of ultrafine vehicular particles in rapidly and perhaps randomly varying high concentration environments such as roadside, on-road and tunnel. In this study, particle size distributions in these environments were found to vary as rapidly as one second frequently. This poses the question on the generality of using averages of long scan-time spectra for dynamic and/or mechanistic studies in rapidly and perhaps randomly varying high concentration environments. One-second EEPS data taken at roadside, on roads and in tunnels by a mobile platform are time-averaged to yield 5, 10, 30 and 120 s distributions to answer this question.

  6. Simultaneous measurement of particle velocity and size based on gray difference and autocorrelation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The gray of two images of a same particle taken by a digital camera with different exposure times is different too. Based on the gray difference of particle images in a double-exposed photo and autocorrelation processing of digital images,this paper proposes a method for measuring particle velocities and sizes simultaneously. This paper also introduces the theoretical foundation of this method,the process of particle imaging and image processing,and the simultaneous measurement of velocity and size of a low speed flow field with 35 μm and 75 μm standard particles. The graphical measurement results can really reflect the flow characteristics of the flow field. In addition,although the measured velocity and size histograms of these two kinds of standard particles are slightly wider than the theoretical ones,they are all still similar to the normal distribution,and the peak velocities and diameters of the histograms are consistent with the default values. Therefore,this measurement method is capable of providing moderate measurement accuracy,and it can be further developed for high-speed flow field measurements.

  7. Chemically generated convective transport of micron sized particles

    Science.gov (United States)

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

    2015-11-01

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

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

    International Nuclear Information System (INIS)

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

  9. Interpretation of aerosol trace metal particle size distributions

    International Nuclear Information System (INIS)

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

  10. CHARACTERISTICS OF SINGLE PARTICLE COAL COMBUSTION

    Science.gov (United States)

    The paper discusses the measurement of the burning history of single coal particles, using a two-color optical pyrometer. rom intensity traces at two wavelengths, information on burning times and temperatures, the duration of a volatile flame, and projected areas was obtained for...

  11. 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.

  12. Diffusion limited aggregation of particles with different sizes: Fractal dimension change by anisotropic growth

    Science.gov (United States)

    Braga, F. L.; Mattos, O. A.; Amorin, V. S.; Souza, A. B.

    2015-07-01

    Clusters formation models have been extensively studied in literature, and one of the main task of this research area is the analysis of the particle aggregation processes. Some work support that the main characteristics of this processes are strictly correlated to the cluster morphology, for example in DLA. It is expected that in the DLA clusters formation with particles containing different sizes the modification of the aggregation processes can be responsible for changes in the DLA morphology. The present article is going to analyze the formation of DLA clusters of particles with different sizes and show that the aggregates obtained by this approach generate an angle selection mechanism on dendritic growth that influences the shielding effect of the DLA edge and affect the fractal dimension of the clusters.

  13. Totally asymmetric exclusion processes with particles of arbitrary size

    International Nuclear Information System (INIS)

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

  14. Totally asymmetric exclusion processes with particles of arbitrary size

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-02-28

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

  15. Underlying event characteristics and their dependence on jet size of charged-particle jet events in pp collisions at $\\sqrt{s}$ = 7 TeV with the ATLAS detector

    CERN Document Server

    Aad, Georges; Abdallah, Jalal; Abdel Khalek, Samah; Abdelalim, Ahmed Ali; Abdinov, Ovsat; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Acerbi, Emilio; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Addy, Tetteh; Adelman, Jahred; Adomeit, Stefanie; Adragna, Paolo; Adye, Tim; Aefsky, Scott; Aguilar-Saavedra, Juan Antonio; Aharrouche, Mohamed; Ahlen, Steven; Ahles, Florian; Ahmad, Ashfaq; Ahsan, Mahsana; Aielli, Giulio; Akdogan, Taylan; Å kesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Akiyama, Kunihiro; Alam, Mohammad; Alam, Muhammad Aftab; Albert, Justin; Albrand, Solveig; Aleksa, Martin; Aleksandrov, Igor; Alessandria, Franco; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alison, John; Allbrooke, Benedict; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alvarez Gonzalez, Barbara; Alviggi, Mariagrazia; Amako, Katsuya; Amelung, Christoph; Ammosov, Vladimir; Amorim, Antonio; Amram, Nir; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Anduaga, Xabier; Anger, Philipp; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoun, Sahar; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Arce, Ayana; Arfaoui, Samir; Arguin, Jean-Francois; Arik, Engin; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnal, Vanessa; Arnault, Christian; Artamonov, Andrei; Artoni, Giacomo; Arutinov, David; Asai, Shoji; Asfandiyarov, Ruslan; Ask, Stefan; Å sman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astbury, Alan; Aubert, Bernard; Auge, Etienne; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Avramidou, Rachel Maria; Axen, David; Azuelos, Georges; Azuma, Yuya; Baak, Max; Baccaglioni, Giuseppe; Bacci, Cesare; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Badescu, Elisabeta; Bagnaia, Paolo; Bahinipati, Seema; Bai, Yu; Bailey, David; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Mark; Baker, Sarah; Banas, Elzbieta; Banerjee, Piyali; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barbaro Galtieri, Angela; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Barrillon, Pierre; Bartoldus, Rainer; Barton, Adam Edward; Bartsch, Valeria; Bates, Richard; Batkova, Lucia; Batley, Richard; Battaglia, Andreas; Battistin, Michele; Bauer, Florian; Bawa, Harinder Singh; Beale, Steven; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Becker, Anne Kathrin; Becker, Sebastian; Beckingham, Matthew; Becks, Karl-Heinz; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Begel, Michael; Behar Harpaz, Silvia; Beimforde, Michael; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellina, Francesco; Bellomo, Massimiliano; Belloni, Alberto; Beloborodova, Olga; Belotskiy, Konstantin; Beltramello, Olga; Benary, Odette; Benchekroun, Driss; Bendtz, Katarina; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez Garcia, Jorge-Armando; Benjamin, Douglas; Benoit, Mathieu; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, Jürg; Bernat, Pauline; Bernhard, Ralf; Bernius, Catrin; Berry, Tracey; Bertella, Claudia; Bertin, Antonio; Bertolucci, Federico; Besana, Maria Ilaria; Besjes, Geert-Jan; Besson, Nathalie; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Bierwagen, Katharina; Biesiada, Jed; Biglietti, Michela; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare; Biscarat, Catherine; Bitenc, Urban; Black, Kevin; Blair, Robert; Blanchard, Jean-Baptiste; Blanchot, Georges; Blazek, Tomas; Blocker, Craig; Blocki, Jacek; Blondel, Alain; Blum, Walter; Blumenschein, Ulrike; Bobbink, Gerjan; Bobrovnikov, Victor; Bocchetta, Simona Serena; Bocci, Andrea; Boddy, Christopher Richard; Boehler, Michael; Boek, Jennifer; Boelaert, Nele; Bogaerts, Joannes Andreas; Bogdanchikov, Alexander; Bogouch, Andrei; Bohm, Christian; Bohm, Jan; Boisvert, Veronique; Bold, Tomasz; Boldea, Venera; Bolnet, Nayanka Myriam; Bomben, Marco; Bona, Marcella; Bondioli, Mario; Boonekamp, Maarten; Booth, Chris; Bordoni, Stefania; Borer, Claudia; 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Carlino, Gianpaolo; Carminati, Leonardo; Caron, Bryan; Caron, Sascha; Carquin, Edson; Carrillo Montoya, German D; Carter, Antony; Carter, Janet; Carvalho, João; Casadei, Diego; Casado, Maria Pilar; Cascella, Michele; Caso, Carlo; Castaneda Hernandez, Alfredo Martin; Castaneda-Miranda, Elizabeth; Castillo Gimenez, Victoria; Castro, Nuno Filipe; Cataldi, Gabriella; Catastini, Pierluigi; Catinaccio, Andrea; Catmore, James; Cattai, Ariella; Cattani, Giordano; Caughron, Seth; Cavalleri, Pietro; Cavalli, Donatella; Cavalli-Sforza, Matteo; Cavasinni, Vincenzo; Ceradini, Filippo; Cerqueira, Augusto Santiago; Cerri, Alessandro; Cerrito, Lucio; Cerutti, Fabio; Cetin, Serkant Ali; Chafaq, Aziz; Chakraborty, Dhiman; Chalupkova, Ina; Chan, Kevin; Chapleau, Bertrand; Chapman, John Derek; Chapman, John Wehrley; Chareyre, Eve; Charlton, Dave; Chavda, Vikash; Chavez Barajas, Carlos Alberto; Cheatham, Susan; Chekanov, Sergei; Chekulaev, Sergey; Chelkov, Gueorgui; Chelstowska, Magda Anna; Chen, Chunhui; Chen, Hucheng; Chen, Shenjian; Chen, Xin; Cheplakov, Alexander; Cherkaoui El Moursli, Rajaa; Chernyatin, Valeriy; Cheu, Elliott; Cheung, Sing-Leung; Chevalier, Laurent; Chiefari, Giovanni; Chikovani, Leila; Childers, John Taylor; Chilingarov, Alexandre; Chiodini, Gabriele; Chisholm, Andrew; Chislett, Rebecca Thalatta; Chizhov, Mihail; Choudalakis, Georgios; Chouridou, Sofia; Christidi, Illectra-Athanasia; Christov, Asen; Chromek-Burckhart, Doris; Chu, Ming-Lee; Chudoba, Jiri; Ciapetti, Guido; Ciftci, Abbas Kenan; Ciftci, Rena; Cinca, Diane; Cindro, Vladimir; Ciocca, Claudia; Ciocio, Alessandra; Cirilli, Manuela; Citterio, Mauro; Ciubancan, Mihai; Clark, Allan G; Clark, Philip James; Cleland, Bill; Clemens, Jean-Claude; Clement, Benoit; Clement, Christophe; Coadou, Yann; Cobal, Marina; Coccaro, Andrea; Cochran, James H; Coe, Paul; Cogan, Joshua Godfrey; Coggeshall, James; Cogneras, Eric; Colas, Jacques; Colijn, Auke-Pieter; Collins, Neil; Collins-Tooth, Christopher; Collot, Johann; Colombo, Tommaso; Colon, German; Conde Muiño, Patricia; Coniavitis, Elias; Conidi, Maria Chiara; Consonni, Sofia Maria; Consorti, Valerio; Constantinescu, Serban; Conta, Claudio; Conti, Geraldine; Conventi, Francesco; Cooke, Mark; Cooper, Ben; Cooper-Sarkar, Amanda; Copic, Katherine; Cornelissen, Thijs; Corradi, Massimo; Corriveau, Francois; Cortes-Gonzalez, Arely; Cortiana, Giorgio; Costa, Giuseppe; Costa, María José; Costanzo, Davide; Costin, Tudor; Côté, David; Courneyea, Lorraine; Cowan, Glen; Cowden, Christopher; Cox, Brian; Cranmer, Kyle; Crescioli, Francesco; Cristinziani, Markus; Crosetti, Giovanni; Crupi, Roberto; Crépé-Renaudin, Sabine; Cuciuc, Constantin-Mihai; Cuenca Almenar, Cristóbal; Cuhadar Donszelmann, Tulay; Curatolo, Maria; Curtis, Chris; Cuthbert, Cameron; Cwetanski, Peter; Czirr, Hendrik; Czodrowski, Patrick; Czyczula, Zofia; D'Auria, Saverio; D'Onofrio, Monica; D'Orazio, Alessia; Da Cunha Sargedas De Sousa, Mario Jose; Da Via, Cinzia; Dabrowski, Wladyslaw; Dafinca, Alexandru; Dai, Tiesheng; Dallapiccola, Carlo; Dam, Mogens; Dameri, Mauro; Damiani, Daniel; Danielsson, Hans Olof; Dao, Valerio; Darbo, Giovanni; Darlea, Georgiana Lavinia; Davey, Will; Davidek, Tomas; Davidson, Nadia; Davidson, Ruth; Davies, Eleanor; Davies, Merlin; Davison, Adam; Davygora, Yuriy; Dawe, Edmund; Dawson, Ian; Daya-Ishmukhametova, Rozmin; De, Kaushik; de Asmundis, Riccardo; De Castro, Stefano; De Cecco, Sandro; de Graat, Julien; De Groot, Nicolo; de Jong, Paul; De La Taille, Christophe; De la Torre, Hector; De Lorenzi, Francesco; de Mora, Lee; De Nooij, Lucie; De Pedis, Daniele; De Salvo, Alessandro; De Sanctis, Umberto; De Santo, Antonella; De Vivie De Regie, Jean-Baptiste; De Zorzi, Guido; Dearnaley, William James; Debbe, Ramiro; Debenedetti, Chiara; Dechenaux, Benjamin; Dedovich, Dmitri; Degenhardt, James; Del Papa, Carlo; Del Peso, Jose; Del Prete, Tarcisio; Delemontex, Thomas; Deliyergiyev, Maksym; Dell'Acqua, Andrea; Dell'Asta, Lidia; Della Pietra, Massimo; della Volpe, Domenico; Delmastro, Marco; Delsart, Pierre-Antoine; Deluca, Carolina; Demers, Sarah; Demichev, Mikhail; Demirkoz, Bilge; Deng, Jianrong; Denisov, Sergey; Derendarz, Dominik; Derkaoui, Jamal Eddine; Derue, Frederic; Dervan, Paul; Desch, Klaus Kurt; Devetak, Erik; Deviveiros, Pier-Olivier; Dewhurst, Alastair; DeWilde, Burton; Dhaliwal, Saminder; Dhullipudi, Ramasudhakar; Di Ciaccio, Anna; Di Ciaccio, Lucia; Di Girolamo, Alessandro; Di Girolamo, Beniamino; Di Luise, Silvestro; Di Mattia, Alessandro; Di Micco, Biagio; Di Nardo, Roberto; Di Simone, Andrea; Di Sipio, Riccardo; Diaz, Marco Aurelio; Diehl, Edward; Dietrich, Janet; Dietzsch, Thorsten; Diglio, Sara; Dindar Yagci, Kamile; Dingfelder, Jochen; Dionisi, Carlo; Dita, Petre; Dita, Sanda; Dittus, Fridolin; Djama, Fares; Djobava, Tamar; do Vale, Maria Aline Barros; Do Valle Wemans, André; Doan, Thi Kieu Oanh; Dobbs, Matt; Dobinson, Robert; Dobos, Daniel; Dobson, Ellie; Dodd, Jeremy; Doglioni, Caterina; Doherty, Tom; Doi, Yoshikuni; Dolejsi, Jiri; Dolenc, Irena; Dolezal, Zdenek; Dolgoshein, Boris; Dohmae, Takeshi; Donadelli, Marisilvia; Donega, Mauro; Donini, Julien; Dopke, Jens; Doria, Alessandra; Dos Anjos, Andre; Dotti, Andrea; Dova, Maria-Teresa; Doxiadis, Alexander; Doyle, Tony; Dris, Manolis; Dubbert, Jörg; Dube, Sourabh; Duchovni, Ehud; Duckeck, Guenter; Dudarev, Alexey; Dudziak, Fanny; Dührssen, Michael; Duerdoth, Ian; Duflot, Laurent; Dufour, Marc-Andre; Dunford, Monica; Duran Yildiz, Hatice; Duxfield, Robert; Dwuznik, Michal; Dydak, Friedrich; Düren, Michael; Ebke, Johannes; Eckweiler, Sebastian; Edmonds, Keith; Edwards, Clive; Edwards, Nicholas Charles; Ehrenfeld, Wolfgang; Eifert, Till; Eigen, Gerald; Einsweiler, Kevin; Eisenhandler, Eric; Ekelof, Tord; El Kacimi, Mohamed; Ellert, Mattias; Elles, Sabine; Ellinghaus, Frank; Ellis, Katherine; Ellis, Nicolas; Elmsheuser, Johannes; Elsing, Markus; Emeliyanov, Dmitry; Engelmann, Roderich; Engl, Albert; Epp, Brigitte; Eppig, Andrew; Erdmann, Johannes; Ereditato, Antonio; Eriksson, Daniel; Ernst, Jesse; Ernst, Michael; Ernwein, Jean; Errede, Deborah; Errede, Steven; Ertel, Eugen; Escalier, Marc; Escobar, Carlos; Espinal Curull, Xavier; Esposito, Bellisario; Etienne, Francois; Etienvre, Anne-Isabelle; Etzion, Erez; Evangelakou, Despoina; Evans, Hal; Fabbri, Laura; Fabre, Caroline; Fakhrutdinov, Rinat; Falciano, Speranza; Fang, Yaquan; Fanti, Marcello; Farbin, Amir; Farilla, Addolorata; Farley, Jason; Farooque, Trisha; Farrell, Steven; Farrington, Sinead; Farthouat, Philippe; Fassnacht, Patrick; Fassouliotis, Dimitrios; Fatholahzadeh, Baharak; Favareto, Andrea; Fayard, Louis; Fazio, Salvatore; Febbraro, Renato; Federic, Pavol; Fedin, Oleg; Fedorko, Wojciech; Fehling-Kaschek, Mirjam; Feligioni, Lorenzo; Fellmann, Denis; Feng, Cunfeng; Feng, Eric; Fenyuk, Alexander; Ferencei, Jozef; Fernando, Waruna; Ferrag, Samir; Ferrando, James; Ferrara, Valentina; Ferrari, Arnaud; Ferrari, Pamela; Ferrari, Roberto; Ferreira de Lima, Danilo Enoque; Ferrer, Antonio; Ferrere, Didier; Ferretti, Claudio; Ferretto Parodi, Andrea; Fiascaris, Maria; Fiedler, Frank; Filipčič, Andrej; Filthaut, Frank; Fincke-Keeler, Margret; Fiolhais, Miguel; Fiorini, Luca; Firan, Ana; Fischer, Gordon; Fisher, Matthew; Flechl, Martin; Fleck, Ivor; Fleckner, Johanna; Fleischmann, Philipp; Fleischmann, Sebastian; Flick, Tobias; Floderus, Anders; Flores Castillo, Luis; Flowerdew, Michael; Fonseca Martin, Teresa; Formica, Andrea; Forti, Alessandra; Fortin, Dominique; Fournier, Daniel; Fox, Harald; Francavilla, Paolo; Franchino, Silvia; Francis, David; Frank, Tal; Franklin, Melissa; Franz, Sebastien; Fraternali, Marco; Fratina, Sasa; French, Sky; Friedrich, Conrad; Friedrich, Felix; Froeschl, Robert; Froidevaux, Daniel; Frost, James; Fukunaga, Chikara; Fullana Torregrosa, Esteban; Fulsom, Bryan Gregory; Fuster, Juan; Gabaldon, Carolina; Gabizon, Ofir; Gadfort, Thomas; Gadomski, Szymon; Gagliardi, Guido; Gagnon, Pauline; Galea, Cristina; Gallas, Elizabeth; Gallo, Valentina Santina; Gallop, Bruce; Gallus, Petr; Gan, KK; Gao, Yongsheng; Gaponenko, Andrei; Garberson, Ford; Garcia-Sciveres, Maurice; García, Carmen; García Navarro, José Enrique; Gardner, Robert; Garelli, Nicoletta; Garitaonandia, Hegoi; Garonne, Vincent; Garvey, John; Gatti, Claudio; Gaudio, Gabriella; Gaur, Bakul; Gauthier, Lea; Gauzzi, Paolo; Gavrilenko, Igor; Gay, Colin; Gaycken, Goetz; Gazis, Evangelos; Ge, Peng; Gecse, Zoltan; Gee, Norman; Geerts, Daniël Alphonsus Adrianus; Geich-Gimbel, Christoph; Gellerstedt, Karl; Gemme, Claudia; Gemmell, Alistair; Genest, Marie-Hélène; Gentile, Simonetta; George, Matthias; George, Simon; Gerlach, Peter; Gershon, Avi; Geweniger, Christoph; Ghazlane, Hamid; Ghodbane, Nabil; Giacobbe, Benedetto; Giagu, Stefano; Giakoumopoulou, Victoria; Giangiobbe, Vincent; Gianotti, Fabiola; Gibbard, Bruce; Gibson, Adam; Gibson, Stephen; Gillberg, Dag; Gillman, Tony; Gingrich, Douglas; Ginzburg, Jonatan; Giokaris, Nikos; Giordani, MarioPaolo; Giordano, Raffaele; Giorgi, Francesco Michelangelo; Giovannini, Paola; Giraud, Pierre-Francois; Giugni, Danilo; Giunta, Michele; Giusti, Paolo; Gjelsten, Bø rge Kile; Gladilin, Leonid; Glasman, Claudia; Glatzer, Julian; Glazov, Alexandre; Glitza, Karl-Walter; Glonti, George; Goddard, Jack Robert; Godfrey, Jennifer; Godlewski, Jan; Goebel, Martin; Göpfert, Thomas; Goeringer, Christian; Gössling, Claus; Goldfarb, Steven; Golling, Tobias; Gomes, Agostinho; Gomez Fajardo, Luz Stella; Gonçalo, Ricardo; Goncalves Pinto Firmino Da Costa, Joao; Gonella, Laura; Gonzalez, Saul; González de la Hoz, Santiago; Gonzalez Parra, Garoe; Gonzalez Silva, Laura; Gonzalez-Sevilla, Sergio; Goodson, Jeremiah Jet; Goossens, Luc; Gorbounov, Petr Andreevich; Gordon, Howard; Gorelov, Igor; Gorfine, Grant; Gorini, Benedetto; Gorini, Edoardo; Gorišek, Andrej; Gornicki, Edward; Gosdzik, Bjoern; Goshaw, Alfred; Gosselink, Martijn; Gostkin, Mikhail Ivanovitch; Gough Eschrich, Ivo; Gouighri, Mohamed; Goujdami, Driss; Goulette, Marc Phillippe; Goussiou, Anna; Goy, Corinne; Gozpinar, Serdar; Grabowska-Bold, Iwona; Grafström, Per; Grahn, Karl-Johan; Grancagnolo, Francesco; Grancagnolo, Sergio; Grassi, Valerio; Gratchev, Vadim; Grau, Nathan; Gray, Heather; Gray, Julia Ann; Graziani, Enrico; Grebenyuk, Oleg; Greenshaw, Timothy; Greenwood, Zeno Dixon; Gregersen, Kristian; Gregor, Ingrid-Maria; Grenier, Philippe; Griffiths, Justin; Grigalashvili, Nugzar; Grillo, Alexander; Grinstein, Sebastian; Grishkevich, Yaroslav; Grivaz, Jean-Francois; Gross, Eilam; Grosse-Knetter, Joern; Groth-Jensen, Jacob; Grybel, Kai; Guest, Daniel; Guicheney, Christophe; Guida, Angelo; Guindon, Stefan; Gul, Umar; Guler, Hulya; Gunther, Jaroslav; Guo, Bin; Guo, Jun; Gushchin, Vladimir; Gutierrez, Phillip; Guttman, Nir; Gutzwiller, Olivier; Guyot, Claude; Gwenlan, Claire; Gwilliam, Carl; Haas, Andy; Haas, Stefan; Haber, Carl; Hadavand, Haleh Khani; Hadley, David; Haefner, Petra; Hahn, Ferdinand; Haider, Stefan; Hajduk, Zbigniew; Hakobyan, Hrachya; Hall, David; Haller, Johannes; Hamacher, Klaus; Hamal, Petr; Hamer, Matthias; Hamilton, Andrew; Hamilton, Samuel; Han, Liang; Hanagaki, Kazunori; Hanawa, Keita; Hance, Michael; Handel, Carsten; Hanke, Paul; Hansen, John Renner; Hansen, Jø rgen Beck; Hansen, Jorn Dines; Hansen, Peter Henrik; Hansson, Per; Hara, Kazuhiko; Hare, Gabriel; Harenberg, Torsten; Harkusha, Siarhei; Harper, Devin; Harrington, Robert; Harris, Orin; Harrison, Karl; Hartert, Jochen; Hartjes, Fred; Haruyama, Tomiyoshi; Harvey, Alex; Hasegawa, Satoshi; Hasegawa, Yoji; Hassani, Samira; Haug, Sigve; Hauschild, Michael; Hauser, Reiner; Havranek, Miroslav; Hawkes, Christopher; Hawkings, Richard John; Hawkins, Anthony David; Hawkins, Donovan; Hayakawa, Takashi; Hayashi, Takayasu; Hayden, Daniel; Hays, Chris; Hayward, Helen; Haywood, Stephen; He, Mao; Head, Simon; Hedberg, Vincent; Heelan, Louise; Heim, Sarah; Heinemann, Beate; Heisterkamp, Simon; Helary, Louis; Heller, Claudio; Heller, Matthieu; Hellman, Sten; Hellmich, Dennis; Helsens, Clement; Henderson, Robert; Henke, Michael; Henrichs, Anna; Henriques Correia, Ana Maria; Henrot-Versille, Sophie; Henry-Couannier, Frédéric; Hensel, Carsten; Henß, Tobias; Hernandez, Carlos Medina; Hernández Jiménez, Yesenia; Herrberg, Ruth; Herten, Gregor; Hertenberger, Ralf; Hervas, Luis; Hesketh, Gavin Grant; Hessey, Nigel; Higón-Rodriguez, Emilio; Hill, John; Hiller, Karl Heinz; Hillert, Sonja; Hillier, Stephen; Hinchliffe, Ian; Hines, Elizabeth; Hirose, Minoru; Hirsch, Florian; Hirschbuehl, Dominic; Hobbs, John; Hod, Noam; Hodgkinson, Mark; Hodgson, Paul; Hoecker, Andreas; Hoeferkamp, Martin; Hoffman, Julia; Hoffmann, Dirk; Hohlfeld, Marc; Holder, Martin; Holmgren, Sven-Olof; Holy, Tomas; Holzbauer, Jenny; Hong, Tae Min; Hooft van Huysduynen, Loek; Horn, Claus; Horner, Stephan; Hostachy, Jean-Yves; Hou, Suen; Hoummada, Abdeslam; Howard, Jacob; Howarth, James; Hristova, Ivana; Hrivnac, Julius; Hruska, Ivan; Hryn'ova, Tetiana; Hsu, Pai-hsien Jennifer; Hsu, Shih-Chieh; Hubacek, Zdenek; Hubaut, Fabrice; Huegging, Fabian; Huettmann, Antje; Huffman, Todd Brian; Hughes, Emlyn; Hughes, Gareth; Huhtinen, Mika; Hurwitz, Martina; Husemann, Ulrich; Huseynov, Nazim; Huston, Joey; Huth, John; Iacobucci, Giuseppe; Iakovidis, Georgios; Ibbotson, Michael; Ibragimov, Iskander; Iconomidou-Fayard, Lydia; Idarraga, John; Iengo, Paolo; Igonkina, Olga; Ikegami, Yoichi; Ikeno, Masahiro; Iliadis, Dimitrios; Ilic, Nikolina; Ince, Tayfun; Inigo-Golfin, Joaquin; Ioannou, Pavlos; Iodice, Mauro; Iordanidou, Kalliopi; Ippolito, Valerio; Irles Quiles, Adrian; Isaksson, Charlie; Ishikawa, Akimasa; Ishino, Masaya; Ishmukhametov, Renat; Issever, Cigdem; Istin, Serhat; Ivashin, Anton; Iwanski, Wieslaw; Iwasaki, Hiroyuki; Izen, Joseph; Izzo, Vincenzo; Jackson, Brett; Jackson, John; Jackson, Paul; Jaekel, Martin; Jain, Vivek; Jakobs, Karl; Jakobsen, Sune; Jakoubek, Tomas; Jakubek, Jan; Jana, Dilip; Jansen, Eric; Jansen, Hendrik; Jantsch, Andreas; Janus, Michel; Jarlskog, Göran; Jeanty, Laura; Jen-La Plante, Imai; Jenni, Peter; Jeremie, Andrea; Jež, Pavel; Jézéquel, Stéphane; Jha, Manoj Kumar; Ji, Haoshuang; Ji, Weina; Jia, Jiangyong; Jiang, Yi; Jimenez Belenguer, Marcos; Jin, Shan; Jinnouchi, Osamu; Joergensen, Morten Dam; Joffe, David; Johansen, Lars; Johansen, Marianne; Johansson, Erik; Johansson, Per; Johnert, Sebastian; Johns, Kenneth; Jon-And, Kerstin; Jones, Graham; Jones, Roger; Jones, Tim; Joram, Christian; Jorge, Pedro; Joshi, Kiran Daniel; Jovicevic, Jelena; Jovin, Tatjana; Ju, Xiangyang; Jung, Christian; Jungst, Ralph Markus; Juranek, Vojtech; Jussel, Patrick; Juste Rozas, Aurelio; Kabana, Sonja; Kaci, Mohammed; Kaczmarska, Anna; Kadlecik, Peter; Kado, Marumi; Kagan, Harris; Kagan, Michael; Kajomovitz, Enrique; Kalinin, Sergey; Kalinovskaya, Lidia; Kama, Sami; Kanaya, Naoko; Kaneda, Michiru; Kaneti, Steven; Kanno, Takayuki; Kantserov, Vadim; Kanzaki, Junichi; Kaplan, Benjamin; Kapliy, Anton; Kaplon, Jan; Kar, Deepak; Karagounis, Michael; Karakostas, Konstantinos; Karnevskiy, Mikhail; Kartvelishvili, Vakhtang; Karyukhin, Andrey; Kashif, Lashkar; Kasieczka, Gregor; Kass, Richard; Kastanas, Alex; Kataoka, Mayuko; Kataoka, Yousuke; Katsoufis, Elias; Katzy, Judith; Kaushik, Venkatesh; Kawagoe, Kiyotomo; Kawamoto, Tatsuo; Kawamura, Gen; Kayl, Manuel; Kazanin, Vassili; Kazarinov, Makhail; Keeler, Richard; Kehoe, Robert; Keil, Markus; Kekelidze, George; Keller, John; Kennedy, John; Kenyon, Mike; Kepka, Oldrich; Kerschen, Nicolas; Kerševan, Borut Paul; Kersten, Susanne; Kessoku, Kohei; Keung, Justin; Khalil-zada, Farkhad; Khandanyan, Hovhannes; Khanov, Alexander; Kharchenko, Dmitri; Khodinov, Alexander; Khomich, Andrei; Khoo, Teng Jian; Khoriauli, Gia; Khoroshilov, Andrey; Khovanskiy, Valery; Khramov, Evgeniy; Khubua, Jemal; Kim, Hyeon Jin; Kim, Min Suk; Kim, Shinhong; Kimura, Naoki; Kind, Oliver; King, Barry; King, Matthew; King, Robert Steven Beaufoy; Kirk, Julie; Kiryunin, Andrey; Kishimoto, Tomoe; Kisielewska, Danuta; Kittelmann, Thomas; Kiver, Andrey; Kladiva, Eduard; Klein, Max; Klein, Uta; Kleinknecht, Konrad; Klemetti, Miika; Klier, Amit; Klimek, Pawel; Klimentov, Alexei; Klingenberg, Reiner; Klinger, Joel Alexander; Klinkby, Esben; Klioutchnikova, Tatiana; Klok, Peter; Klous, Sander; Kluge, Eike-Erik; Kluge, Thomas; Kluit, Peter; Kluth, Stefan; Knecht, Neil; Kneringer, Emmerich; Knoops, Edith; Knue, Andrea; Ko, Byeong Rok; Kobayashi, Tomio; Kobel, Michael; Kocian, Martin; Kodys, Peter; Köneke, Karsten; König, Adriaan; Koenig, Sebastian; Köpke, Lutz; Koetsveld, Folkert; Koevesarki, Peter; Koffas, Thomas; Koffeman, Els; Kogan, Lucy Anne; Kohlmann, Simon; Kohn, Fabian; Kohout, Zdenek; Kohriki, Takashi; Koi, Tatsumi; Kolachev, Guennady; Kolanoski, Hermann; Kolesnikov, Vladimir; Koletsou, Iro; Koll, James; Kollefrath, Michael; Komar, Aston; Komori, Yuto; Kondo, Takahiko; Kono, Takanori; Kononov, Anatoly; Konoplich, Rostislav; Konstantinidis, Nikolaos; Kootz, Andreas; Koperny, Stefan; Korcyl, Krzysztof; Kordas, Kostantinos; Korn, Andreas; Korol, Aleksandr; Korolkov, Ilya; Korolkova, Elena; Korotkov, Vladislav; Kortner, Oliver; Kortner, Sandra; Kostyukhin, Vadim; Kotov, Sergey; Kotov, Vladislav; Kotwal, Ashutosh; Kourkoumelis, Christine; Kouskoura, Vasiliki; Koutsman, Alex; Kowalewski, Robert Victor; Kowalski, Tadeusz; Kozanecki, Witold; Kozhin, Anatoly; Kral, Vlastimil; Kramarenko, Viktor; Kramberger, Gregor; Krasny, Mieczyslaw Witold; Krasznahorkay, Attila; Kraus, James; Kraus, Jana; Kreiss, Sven; Krejci, Frantisek; Kretzschmar, Jan; Krieger, Nina; Krieger, Peter; Kroeninger, Kevin; Kroha, Hubert; Kroll, Joe; Kroseberg, Juergen; Krstic, Jelena; Kruchonak, Uladzimir; Krüger, Hans; Kruker, Tobias; Krumnack, Nils; Krumshteyn, Zinovii; Kruth, Andre; Kubota, Takashi; Kuday, Sinan; Kuehn, Susanne; Kugel, Andreas; Kuhl, Thorsten; Kuhn, Dietmar; Kukhtin, Victor; Kulchitsky, Yuri; Kuleshov, Sergey; Kummer, Christian; Kuna, Marine; Kunkle, Joshua; Kupco, Alexander; Kurashige, Hisaya; Kurata, Masakazu; Kurochkin, Yurii; Kus, Vlastimil; Kuwertz, Emma Sian; Kuze, Masahiro; Kvita, Jiri; Kwee, Regina; La Rosa, Alessandro; La Rotonda, Laura; Labarga, Luis; Labbe, Julien; Lablak, Said; Lacasta, Carlos; Lacava, Francesco; Lacker, Heiko; Lacour, Didier; Lacuesta, Vicente Ramón; Ladygin, Evgueni; Lafaye, Remi; Laforge, Bertrand; Lagouri, Theodota; Lai, Stanley; Laisne, Emmanuel; Lamanna, Massimo; Lambourne, Luke; Lampen, Caleb; Lampl, Walter; Lancon, Eric; Landgraf, Ulrich; Landon, Murrough; Lane, Jenna; Lange, Clemens; Lankford, Andrew; Lanni, Francesco; Lantzsch, Kerstin; Laplace, Sandrine; Lapoire, Cecile; Laporte, Jean-Francois; Lari, Tommaso; Larner, Aimee; Lassnig, Mario; Laurelli, Paolo; Lavorini, Vincenzo; Lavrijsen, Wim; Laycock, Paul; Le Dortz, Olivier; Le Guirriec, Emmanuel; Le Maner, Christophe; Le Menedeu, Eve; LeCompte, Thomas; Ledroit-Guillon, Fabienne Agnes Marie; Lee, Hurng-Chun; Lee, Jason; Lee, Shih-Chang; Lee, Lawrence; Lefebvre, Michel; Legendre, Marie; LeGeyt, Benjamin; Legger, Federica; Leggett, Charles; Lehmacher, Marc; Lehmann Miotto, Giovanna; Lei, Xiaowen; Leite, Marco Aurelio Lisboa; Leitner, Rupert; Lellouch, Daniel; Lemmer, Boris; Lendermann, Victor; Leney, Katharine; Lenz, Tatiana; Lenzen, Georg; Lenzi, Bruno; Leonhardt, Kathrin; Leontsinis, Stefanos; Lepold, Florian; Leroy, Claude; Lessard, Jean-Raphael; Lester, Christopher; Lester, Christopher Michael; Levêque, Jessica; Levin, Daniel; Levinson, Lorne; Lewis, Adrian; Lewis, George; Leyko, Agnieszka; Leyton, Michael; Li, Bo; Li, Haifeng; Li, Shu; Li, Xuefei; Liang, Zhijun; Liao, Hongbo; Liberti, Barbara; Lichard, Peter; Lichtnecker, Markus; Lie, Ki; Liebig, Wolfgang; Limbach, Christian; Limosani, Antonio; Limper, Maaike; Lin, Simon; Linde, Frank; Linnemann, James; Lipeles, Elliot; Lipniacka, Anna; Liss, Tony; Lissauer, David; Lister, Alison; Litke, Alan; Liu, Chuanlei; Liu, Dong; Liu, Hao; Liu, Jianbei; Liu, Minghui; Liu, Yanwen; Livan, Michele; Livermore, Sarah; Lleres, Annick; Llorente Merino, Javier; Lloyd, Stephen; Lobodzinska, Ewelina; Loch, Peter; Lockman, William; Loddenkoetter, Thomas; Loebinger, Fred; Loginov, Andrey; Loh, Chang Wei; Lohse, Thomas; Lohwasser, Kristin; Lokajicek, Milos; Lombardo, Vincenzo Paolo; Long, Robin Eamonn; Lopes, Lourenco; Lopez Mateos, David; Lorenz, Jeanette; Lorenzo Martinez, Narei; Losada, Marta; Loscutoff, Peter; Lo Sterzo, Francesco; Losty, Michael; Lou, Xinchou; Lounis, Abdenour; Loureiro, Karina; Love, Jeremy; Love, Peter; Lowe, Andrew; Lu, Feng; Lubatti, Henry; Luci, Claudio; Lucotte, Arnaud; Ludwig, Andreas; Ludwig, Dörthe; Ludwig, Inga; Ludwig, Jens; Luehring, Frederick; Luijckx, Guy; Lukas, Wolfgang; Lumb, Debra; Luminari, Lamberto; Lund, Esben; Lund-Jensen, Bengt; Lundberg, Björn; Lundberg, Johan; Lundquist, Johan; Lungwitz, Matthias; Lynn, David; Lytken, Else; Ma, Hong; Ma, Lian Liang; Macana Goia, Jorge Andres; Maccarrone, Giovanni; Macchiolo, Anna; Maček, Boštjan; Machado Miguens, Joana; Mackeprang, Rasmus; Madaras, Ronald; Mader, Wolfgang; Maenner, Reinhard; Maeno, Tadashi; Mättig, Peter; Mättig, Stefan; Magnoni, Luca; Magradze, Erekle; Mahboubi, Kambiz; Mahmoud, Sara; Mahout, Gilles; Maiani, Camilla; Maidantchik, Carmen; Maio, Amélia; Majewski, Stephanie; Makida, Yasuhiro; Makovec, Nikola; Mal, Prolay; Malaescu, Bogdan; Malecki, Pawel; Malecki, Piotr; Maleev, Victor; Malek, Fairouz; Mallik, Usha; Malon, David; Malone, Caitlin; Maltezos, Stavros; Malyshev, Vladimir; Malyukov, Sergei; Mameghani, Raphael; Mamuzic, Judita; Manabe, Atsushi; Mandelli, Luciano; Mandić, Igor; Mandrysch, Rocco; Maneira, José; Mangeard, Pierre-Simon; Manhaes de Andrade Filho, Luciano; Mann, Alexander; Manning, Peter; Manousakis-Katsikakis, Arkadios; Mansoulie, Bruno; Mapelli, Alessandro; Mapelli, Livio; March, Luis; Marchand, Jean-Francois; Marchese, Fabrizio; Marchiori, Giovanni; Marcisovsky, Michal; Marino, Christopher; Marroquim, Fernando; Marshall, Zach; Martens, Kalen; Marti-Garcia, Salvador; Martin, Brian; Martin, Brian; Martin, Jean-Pierre; Martin, Tim; Martin, Victoria Jane; Martin dit Latour, Bertrand; Martin-Haugh, Stewart; Martinez, Mario; Martinez Outschoorn, Verena; Martyniuk, Alex; Marx, Marilyn; Marzano, Francesco; Marzin, Antoine; Masetti, Lucia; Mashimo, Tetsuro; Mashinistov, Ruslan; Masik, Jiri; Maslennikov, Alexey; Massa, Ignazio; Massaro, Graziano; Massol, Nicolas; Mastroberardino, Anna; Masubuchi, Tatsuya; Matricon, Pierre; Matsunaga, Hiroyuki; Matsushita, Takashi; Mattravers, Carly; Maurer, Julien; Maxfield, Stephen; Mayne, Anna; Mazini, Rachid; Mazur, Michael; Mazzaferro, Luca; Mazzanti, Marcello; Mc Kee, Shawn Patrick; McCarn, Allison; McCarthy, Robert; McCarthy, Tom; McCubbin, Norman; McFarlane, Kenneth; Mcfayden, Josh; McGlone, Helen; Mchedlidze, Gvantsa; Mclaughlan, Tom; McMahon, Steve; McPherson, Robert; Meade, Andrew; Mechnich, Joerg; Mechtel, Markus; Medinnis, Mike; Meera-Lebbai, Razzak; Meguro, Tatsuma; Mehdiyev, Rashid; Mehlhase, Sascha; Mehta, Andrew; Meier, Karlheinz; Meirose, Bernhard; Melachrinos, Constantinos; Mellado Garcia, Bruce Rafael; Meloni, Federico; Mendoza Navas, Luis; Meng, Zhaoxia; Mengarelli, Alberto; Menke, Sven; Meoni, Evelin; Mercurio, Kevin Michael; Mermod, Philippe; Merola, Leonardo; Meroni, Chiara; Merritt, Frank; Merritt, Hayes; Messina, Andrea; Metcalfe, Jessica; Mete, Alaettin Serhan; Meyer, Carsten; Meyer, Christopher; Meyer, Jean-Pierre; Meyer, Jochen; Meyer, Joerg; Meyer, Thomas Christian; Meyer, W Thomas; Miao, Jiayuan; Michal, Sebastien; Micu, Liliana; Middleton, Robin; Migas, Sylwia; Mijović, Liza; Mikenberg, Giora; Mikestikova, Marcela; Mikuž, Marko; Miller, David; Miller, Robert; Mills, Bill; Mills, Corrinne; Milov, Alexander; Milstead, David; Milstein, Dmitry; Minaenko, Andrey; Miñano Moya, Mercedes; Minashvili, Irakli; Mincer, Allen; Mindur, Bartosz; Mineev, Mikhail; Ming, Yao; Mir, Lluisa-Maria; Mirabelli, Giovanni; Mitrevski, Jovan; Mitsou, Vasiliki A; Mitsui, Shingo; Miyagawa, Paul; Miyazaki, Kazuki; Mjörnmark, Jan-Ulf; Moa, Torbjoern; Moed, Shulamit; Moeller, Victoria; Mönig, Klaus; Möser, Nicolas; Mohapatra, Soumya; Mohr, Wolfgang; Moles-Valls, Regina; Molina-Perez, Jorge; Monk, James; Monnier, Emmanuel; Montesano, Simone; Monticelli, Fernando; Monzani, Simone; Moore, Roger; Moorhead, Gareth; Mora Herrera, Clemencia; Moraes, Arthur; Morange, Nicolas; Morel, Julien; Morello, Gianfranco; Moreno, Deywis; Moreno Llácer, María; Morettini, Paolo; Morgenstern, Marcus; Morii, Masahiro; Morin, Jerome; Morley, Anthony Keith; Mornacchi, Giuseppe; Morris, John; Morvaj, Ljiljana; Moser, Hans-Guenther; Mosidze, Maia; Moss, Josh; Mount, Richard; Mountricha, Eleni; Mouraviev, Sergei; Moyse, Edward; Mueller, Felix; Mueller, James; Mueller, Klemens; Müller, Thomas; Mueller, Timo; Muenstermann, Daniel; Munwes, Yonathan; Murray, Bill; Mussche, Ido; Musto, Elisa; Myagkov, Alexey; Myska, Miroslav; Nadal, Jordi; Nagai, Koichi; Nagano, Kunihiro; Nagarkar, Advait; Nagasaka, Yasushi; Nagel, Martin; Nairz, Armin Michael; Nakahama, Yu; Nakamura, Koji; Nakamura, Tomoaki; Nakano, Itsuo; Nanava, Gizo; Napier, Austin; Narayan, Rohin; Nash, Michael; Nattermann, Till; Naumann, Thomas; Navarro, Gabriela; Neal, Homer; Nechaeva, Polina; Neep, Thomas James; Negri, Andrea; Negri, Guido; Nektarijevic, Snezana; Nelson, Andrew; Nelson, Timothy Knight; Nemecek, Stanislav; Nemethy, Peter; Nepomuceno, Andre Asevedo; Nessi, Marzio; Neubauer, Mark; Neusiedl, Andrea; Neves, Ricardo; Nevski, Pavel; Newman, Paul; Nguyen Thi Hong, Van; Nickerson, Richard; Nicolaidou, Rosy; Nicquevert, Bertrand; Niedercorn, Francois; Nielsen, Jason; Nikiforou, Nikiforos; Nikiforov, Andriy; Nikolaenko, Vladimir; Nikolic-Audit, Irena; Nikolics, Katalin; Nikolopoulos, Konstantinos; Nilsen, Henrik; Nilsson, Paul; Ninomiya, Yoichi; Nisati, Aleandro; Nishiyama, Tomonori; Nisius, Richard; Nodulman, Lawrence; Nomachi, Masaharu; Nomidis, Ioannis; Nordberg, Markus; Norton, Peter; Novakova, Jana; Nozaki, Mitsuaki; Nozka, Libor; Nugent, Ian Michael; Nuncio-Quiroz, Adriana-Elizabeth; Nunes Hanninger, Guilherme; Nunnemann, Thomas; Nurse, Emily; O'Brien, Brendan Joseph; O'Neale, Steve; O'Neil, Dugan; O'Shea, Val; Oakes, Louise Beth; Oakham, Gerald; Oberlack, Horst; Ocariz, Jose; Ochi, Atsuhiko; Oda, Susumu; Odaka, Shigeru; Odier, Jerome; Ogren, Harold; Oh, Alexander; Oh, Seog; Ohm, Christian; Ohshima, Takayoshi; Okada, Shogo; Okawa, Hideki; Okumura, Yasuyuki; Okuyama, Toyonobu; Olariu, Albert; Olchevski, Alexander; Olivares Pino, Sebastian Andres; Oliveira, Miguel Alfonso; Oliveira Damazio, Denis; Oliver Garcia, Elena; Olivito, Dominick; Olszewski, Andrzej; Olszowska, Jolanta; Onofre, António; Onyisi, Peter; Oram, Christopher; Oreglia, Mark; Oren, Yona; Orestano, Domizia; Orlando, Nicola; Orlov, Iliya; Oropeza Barrera, Cristina; Orr, Robert; Osculati, Bianca; Ospanov, Rustem; Osuna, Carlos; Otero y Garzon, Gustavo; Ottersbach, John; Ouchrif, Mohamed; Ouellette, Eric; Ould-Saada, Farid; Ouraou, Ahmimed; Ouyang, Qun; Ovcharova, Ana; Owen, Mark; Owen, Simon; Ozcan, Veysi Erkcan; Ozturk, Nurcan; Pacheco Pages, Andres; Padilla Aranda, Cristobal; Pagan Griso, Simone; Paganis, Efstathios; Paige, Frank; Pais, Preema; Pajchel, Katarina; Palacino, Gabriel; Paleari, Chiara; Palestini, Sandro; Pallin, Dominique; Palma, Alberto; Palmer, Jody; Pan, Yibin; Panagiotopoulou, Evgenia; Pani, Priscilla; Panikashvili, Natalia; Panitkin, Sergey; Pantea, Dan; Papadelis, Aras; Papadopoulou, Theodora; Paramonov, Alexander; Paredes Hernandez, Daniela; Park, Woochun; Parker, Andy; Parodi, Fabrizio; Parsons, John; Parzefall, Ulrich; Pashapour, Shabnaz; Pasqualucci, Enrico; Passaggio, Stefano; Passeri, Antonio; Pastore, Fernanda; Pastore, Francesca; Pásztor, Gabriella; Pataraia, Sophio; Patel, Nikhul; Pater, Joleen; Patricelli, Sergio; Pauly, Thilo; Pecsy, Martin; Pedraza Morales, Maria Isabel; Peleganchuk, Sergey; Pelikan, Daniel; Peng, Haiping; Penning, Bjoern; Penson, Alexander; Penwell, John; Perantoni, Marcelo; Perez, Kerstin; Perez Cavalcanti, Tiago; Perez Codina, Estel; Pérez García-Estañ, María Teresa; Perez Reale, Valeria; Perini, Laura; Pernegger, Heinz; Perrino, Roberto; Perrodo, Pascal; Persembe, Seda; Peshekhonov, Vladimir; Peters, Krisztian; Petersen, Brian; Petersen, Jorgen; Petersen, Troels; Petit, Elisabeth; Petridis, Andreas; Petridou, Chariclia; Petrolo, Emilio; Petrucci, Fabrizio; Petschull, Dennis; Petteni, Michele; Pezoa, Raquel; Phan, Anna; Phillips, Peter William; Piacquadio, Giacinto; Picazio, Attilio; Piccaro, Elisa; Piccinini, Maurizio; Piec, Sebastian Marcin; Piegaia, Ricardo; Pignotti, David; Pilcher, James; Pilkington, Andrew; Pina, João Antonio; Pinamonti, Michele; Pinder, Alex; Pinfold, James; Pinto, Belmiro; Pizio, Caterina; Plamondon, Mathieu; Pleier, Marc-Andre; Plotnikova, Elena; Poblaguev, Andrei; Poddar, Sahill; Podlyski, Fabrice; Poggioli, Luc; Poghosyan, Tatevik; Pohl, Martin; Polci, Francesco; Polesello, Giacomo; Policicchio, Antonio; Polini, Alessandro; Poll, James; Polychronakos, Venetios; Pomarede, Daniel Marc; Pomeroy, Daniel; Pommès, Kathy; Pontecorvo, Ludovico; Pope, Bernard; Popeneciu, Gabriel Alexandru; Popovic, Dragan; Poppleton, Alan; Portell Bueso, Xavier; Pospelov, Guennady; Pospisil, Stanislav; Potrap, Igor; Potter, Christina; Potter, Christopher; Poulard, Gilbert; Poveda, Joaquin; Pozdnyakov, Valery; Prabhu, Robindra; Pralavorio, Pascal; Pranko, Aliaksandr; Prasad, Srivas; Pravahan, Rishiraj; Prell, Soeren; Pretzl, Klaus Peter; Price, Darren; Price, Joe; Price, Lawrence; Prieur, Damien; Primavera, Margherita; Prokofiev, Kirill; Prokoshin, Fedor; Protopopescu, Serban; Proudfoot, James; Prudent, Xavier; Przybycien, Mariusz; Przysiezniak, Helenka; Psoroulas, Serena; Ptacek, Elizabeth; Pueschel, Elisa; Purdham, John; Purohit, Milind; Puzo, Patrick; Pylypchenko, Yuriy; Qian, Jianming; Quadt, Arnulf; Quarrie, David; Quayle, William; Quinonez, Fernando; Raas, Marcel; Radescu, Voica; Radloff, Peter; Rador, Tonguc; Ragusa, Francesco; Rahal, Ghita; Rahimi, Amir; Rahm, David; Rajagopalan, Srinivasan; Rammensee, Michael; Rammes, Marcus; Randle-Conde, Aidan Sean; Randrianarivony, Koloina; Rauscher, Felix; Rave, Tobias Christian; Raymond, Michel; Read, Alexander Lincoln; Rebuzzi, Daniela; Redelbach, Andreas; Redlinger, George; Reece, Ryan; Reeves, Kendall; Reinherz-Aronis, Erez; Reinsch, Andreas; Reisinger, Ingo; Rembser, Christoph; Ren, Zhongliang; Renaud, Adrien; Rescigno, Marco; Resconi, Silvia; Resende, Bernardo; Reznicek, Pavel; Rezvani, Reyhaneh; Richter, Robert; Richter-Was, Elzbieta; Ridel, Melissa; Rijpstra, Manouk; Rijssenbeek, Michael; Rimoldi, Adele; Rinaldi, Lorenzo; Rios, Ryan Randy; Riu, Imma; Rivoltella, Giancesare; Rizatdinova, Flera; Rizvi, Eram; Robertson, Steven; Robichaud-Veronneau, Andree; Robinson, Dave; Robinson, James; Robson, Aidan; Rocha de Lima, Jose Guilherme; Roda, Chiara; Roda Dos Santos, Denis; Roe, Adam; Roe, Shaun; Røhne, Ole; Rolli, Simona; Romaniouk, Anatoli; Romano, Marino; Romeo, Gaston; Romero Adam, Elena; Roos, Lydia; Ros, Eduardo; Rosati, Stefano; Rosbach, Kilian; Rose, Anthony; Rose, Matthew; Rosenbaum, Gabriel; Rosenberg, Eli; Rosendahl, Peter Lundgaard; Rosenthal, Oliver; Rosselet, Laurent; Rossetti, Valerio; Rossi, Elvira; Rossi, Leonardo Paolo; Rotaru, Marina; Roth, Itamar; Rothberg, Joseph; Rousseau, David; Royon, Christophe; Rozanov, Alexander; Rozen, Yoram; Ruan, Xifeng; Rubbo, Francesco; Rubinskiy, Igor; Ruckert, Benjamin; Ruckstuhl, Nicole; Rud, Viacheslav; Rudolph, Christian; Rudolph, Gerald; Rühr, Frederik; Ruggieri, Federico; Ruiz-Martinez, Aranzazu; Rumyantsev, Leonid; Runge, Kay; Rurikova, Zuzana; Rusakovich, Nikolai; Rutherfoord, John; Ruwiedel, Christoph; Ruzicka, Pavel; Ryabov, Yury; Ryan, Patrick; Rybar, Martin; Rybkin, Grigori; Ryder, Nick; Saavedra, Aldo; Sadeh, Iftach; Sadrozinski, Hartmut; Sadykov, Renat; Safai Tehrani, Francesco; Sakamoto, Hiroshi; Salamanna, Giuseppe; Salamon, Andrea; Saleem, Muhammad; Salek, David; Salihagic, Denis; Salnikov, Andrei; Salt, José; Salvachua Ferrando, Belén; Salvatore, Daniela; Salvatore, Pasquale Fabrizio; Salvucci, Antonio; Salzburger, Andreas; Sampsonidis, Dimitrios; Samset, Björn Hallvard; Sanchez, Arturo; Sanchez Martinez, Victoria; Sandaker, Heidi; Sander, Heinz Georg; Sanders, Michiel; Sandhoff, Marisa; Sandoval, Tanya; Sandoval, Carlos; Sandstroem, Rikard; Sankey, Dave; Sansoni, Andrea; Santamarina Rios, Cibran; Santoni, Claudio; Santonico, Rinaldo; Santos, Helena; Saraiva, João; Sarangi, Tapas; Sarkisyan-Grinbaum, Edward; Sarri, Francesca; Sartisohn, Georg; Sasaki, Osamu; Sasao, Noboru; Satsounkevitch, Igor; Sauvage, Gilles; Sauvan, Emmanuel; Sauvan, Jean-Baptiste; Savard, Pierre; Savinov, Vladimir; Savu, Dan Octavian; Sawyer, Lee; Saxon, David; Saxon, James; Sbarra, Carla; Sbrizzi, Antonio; Scallon, Olivia; Scannicchio, Diana; Scarcella, Mark; Schaarschmidt, Jana; Schacht, Peter; Schaefer, Douglas; Schäfer, Uli; Schaepe, Steffen; Schaetzel, Sebastian; Schaffer, Arthur; Schaile, Dorothee; Schamberger, R~Dean; Schamov, Andrey; Scharf, Veit; Schegelsky, Valery; Scheirich, Daniel; Schernau, Michael; Scherzer, Max; Schiavi, Carlo; Schieck, Jochen; Schioppa, Marco; Schlenker, Stefan; Schmidt, Evelyn; Schmieden, Kristof; Schmitt, Christian; Schmitt, Sebastian; Schmitz, Martin; Schneider, Basil; Schnoor, Ulrike; Schoening, Andre; Schott, Matthias; Schouten, Doug; Schovancova, Jaroslava; Schram, Malachi; Schroeder, Christian; Schroer, Nicolai; Schultens, Martin Johannes; Schultes, Joachim; Schultz-Coulon, Hans-Christian; Schulz, Holger; Schumacher, Jan; Schumacher, Markus; Schumm, Bruce; Schune, Philippe; Schwanenberger, Christian; Schwartzman, Ariel; Schwemling, Philippe; Schwienhorst, Reinhard; Schwierz, Rainer; Schwindling, Jerome; Schwindt, Thomas; Schwoerer, Maud; Sciolla, Gabriella; Scott, Bill; Searcy, Jacob; Sedov, George; Sedykh, Evgeny; Seidel, Sally; Seiden, Abraham; Seifert, Frank; Seixas, José; Sekhniaidze, Givi; Sekula, Stephen; Selbach, Karoline Elfriede; Seliverstov, Dmitry; Sellden, Bjoern; Sellers, Graham; Seman, Michal; Semprini-Cesari, Nicola; Serfon, Cedric; Serin, Laurent; Serkin, Leonid; Seuster, Rolf; Severini, Horst; Sfyrla, Anna; Shabalina, Elizaveta; Shamim, Mansoora; Shan, Lianyou; Shank, James; Shao, Qi Tao; Shapiro, Marjorie; Shatalov, Pavel; Shaw, Kate; Sherman, Daniel; Sherwood, Peter; Shibata, Akira; Shichi, Hideharu; Shimizu, Shima; Shimojima, Makoto; Shin, Taeksu; Shiyakova, Maria; Shmeleva, Alevtina; Shochet, Mel; Short, Daniel; Shrestha, Suyog; Shulga, Evgeny; Shupe, Michael; Sicho, Petr; Sidoti, Antonio; Siegert, Frank; Sijacki, Djordje; Silbert, Ohad; Silva, José; Silver, Yiftah; Silverstein, Daniel; Silverstein, Samuel; Simak, Vladislav; Simard, Olivier; Simic, Ljiljana; Simion, Stefan; Simmons, Brinick; Simoniello, Rosa; Simonyan, Margar; Sinervo, Pekka; Sinev, Nikolai; Sipica, Valentin; Siragusa, Giovanni; Sircar, Anirvan; Sisakyan, Alexei; Sivoklokov, Serguei; Sjölin, Jörgen; Sjursen, Therese; Skinnari, Louise Anastasia; Skottowe, Hugh Philip; Skovpen, Kirill; Skubic, Patrick; Slater, Mark; Slavicek, Tomas; Sliwa, Krzysztof; Smakhtin, Vladimir; Smart, Ben; Smirnov, Sergei; Smirnov, Yury; Smirnova, Lidia; Smirnova, Oxana; Smith, Ben Campbell; Smith, Douglas; Smith, Kenway; Smizanska, Maria; Smolek, Karel; Snesarev, Andrei; Snow, Steve; Snow, Joel; Snyder, Scott; Sobie, Randall; Sodomka, Jaromir; Soffer, Abner; Solans, Carlos; Solar, Michael; Solc, Jaroslav; Soldatov, Evgeny; Soldevila, Urmila; Solfaroli Camillocci, Elena; Solodkov, Alexander; Solovyanov, Oleg; Soni, Nitesh; Sopko, Vit; Sopko, Bruno; Sosebee, Mark; Soualah, Rachik; Soukharev, Andrey; Spagnolo, Stefania; Spanò, Francesco; Spighi, Roberto; Spigo, Giancarlo; Spila, Federico; Spiwoks, Ralf; Spousta, Martin; Spreitzer, Teresa; Spurlock, Barry; St Denis, Richard Dante; Stahlman, Jonathan; Stamen, Rainer; Stanecka, Ewa; Stanek, Robert; Stanescu, Cristian; Stanescu-Bellu, Madalina; Stapnes, Steinar; Starchenko, Evgeny; Stark, Jan; Staroba, Pavel; Starovoitov, Pavel; Staude, Arnold; Stavina, Pavel; Steele, Genevieve; Steinbach, Peter; Steinberg, Peter; Stekl, Ivan; Stelzer, Bernd; Stelzer, Harald Joerg; Stelzer-Chilton, Oliver; Stenzel, Hasko; Stern, Sebastian; Stewart, Graeme; Stillings, Jan Andre; Stockton, Mark; Stoerig, Kathrin; Stoicea, Gabriel; Stonjek, Stefan; Strachota, Pavel; Stradling, Alden; Straessner, Arno; Strandberg, Jonas; Strandberg, Sara; Strandlie, Are; Strang, Michael; Strauss, Emanuel; Strauss, Michael; Strizenec, Pavol; Ströhmer, Raimund; Strom, David; Strong, John; Stroynowski, Ryszard; Strube, Jan; Stugu, Bjarne; Stumer, Iuliu; Stupak, John; Sturm, Philipp; Styles, Nicholas Adam; Soh, Dart-yin; Su, Dong; Subramania, Halasya Siva; Succurro, Antonella; Sugaya, Yorihito; Suhr, Chad; Suita, Koichi; Suk, Michal; Sulin, Vladimir; Sultansoy, Saleh; Sumida, Toshi; Sun, Xiaohu; Sundermann, Jan Erik; Suruliz, Kerim; Susinno, Giancarlo; Sutton, Mark; Suzuki, Yu; Suzuki, Yuta; Svatos, Michal; Swedish, Stephen; Sykora, Ivan; Sykora, Tomas; Sánchez, Javier; Ta, Duc; Tackmann, Kerstin; Taffard, Anyes; Tafirout, Reda; Taiblum, Nimrod; Takahashi, Yuta; Takai, Helio; Takashima, Ryuichi; Takeda, Hiroshi; Takeshita, Tohru; Takubo, Yosuke; Talby, Mossadek; Talyshev, Alexey; Tamsett, Matthew; Tanaka, Junichi; Tanaka, Reisaburo; Tanaka, Satoshi; Tanaka, Shuji; Tanasijczuk, Andres Jorge; Tani, Kazutoshi; Tannoury, Nancy; Tapprogge, Stefan; Tardif, Dominique; Tarem, Shlomit; Tarrade, Fabien; Tartarelli, Giuseppe Francesco; Tas, Petr; Tasevsky, Marek; Tassi, Enrico; Tatarkhanov, Mous; Tayalati, Yahya; Taylor, Christopher; Taylor, Frank; Taylor, Geoffrey; Taylor, Wendy; Teinturier, Marthe; Teixeira Dias Castanheira, Matilde; Teixeira-Dias, Pedro; Temming, Kim Katrin; Ten Kate, Herman; Teng, Ping-Kun; Terada, Susumu; Terashi, Koji; Terron, Juan; Testa, Marianna; Teuscher, Richard; Therhaag, Jan; Theveneaux-Pelzer, Timothée; Thoma, Sascha; Thomas, Juergen; Thompson, Emily; Thompson, Paul; Thompson, Peter; Thompson, Stan; Thomsen, Lotte Ansgaard; Thomson, Evelyn; Thomson, Mark; Thun, Rudolf; Tian, Feng; Tibbetts, Mark James; Tic, Tomáš; Tikhomirov, Vladimir; Tikhonov, Yury; Timoshenko, Sergey; Tipton, Paul; Tique Aires Viegas, Florbela De Jes; Tisserant, Sylvain; Todorov, Theodore; Todorova-Nova, Sharka; Toggerson, Brokk; Tojo, Junji; Tokár, Stanislav; Tokunaga, Kaoru; Tokushuku, Katsuo; Tollefson, Kirsten; Tomoto, Makoto; Tompkins, Lauren; Toms, Konstantin; Tonoyan, Arshak; Topfel, Cyril; Topilin, Nikolai; Torchiani, Ingo; Torrence, Eric; Torres, Heberth; Torró Pastor, Emma; Toth, Jozsef; Touchard, Francois; Tovey, Daniel; Trefzger, Thomas; Tremblet, Louis; Tricoli, Alesandro; Trigger, Isabel Marian; Trincaz-Duvoid, Sophie; Tripiana, Martin; Trischuk, William; Trocmé, Benjamin; Troncon, Clara; Trottier-McDonald, Michel; Trzebinski, Maciej; Trzupek, Adam; Tsarouchas, Charilaos; Tseng, Jeffrey; Tsiakiris, Menelaos; Tsiareshka, Pavel; Tsionou, Dimitra; Tsipolitis, Georgios; Tsiskaridze, Shota; Tsiskaridze, Vakhtang; Tskhadadze, Edisher; Tsukerman, Ilya; Tsulaia, Vakhtang; Tsung, Jieh-Wen; Tsuno, Soshi; Tsybychev, Dmitri; Tua, Alan; Tudorache, Alexandra; Tudorache, Valentina; Tuggle, Joseph; Turala, Michal; Turecek, Daniel; Turk Cakir, Ilkay; Turlay, Emmanuel; Turra, Ruggero; Tuts, Michael; Tykhonov, Andrii; Tylmad, Maja; Tyndel, Mike; Tzanakos, George; Uchida, Kirika; Ueda, Ikuo; Ueno, Ryuichi; Ugland, Maren; Uhlenbrock, Mathias; Uhrmacher, Michael; Ukegawa, Fumihiko; Unal, Guillaume; Undrus, Alexander; Unel, Gokhan; Unno, Yoshinobu; Urbaniec, Dustin; Usai, Giulio; Uslenghi, Massimiliano; Vacavant, Laurent; Vacek, Vaclav; Vachon, Brigitte; Vahsen, Sven; Valenta, Jan; Valente, Paolo; Valentinetti, Sara; Valkar, Stefan; Valladolid Gallego, Eva; Vallecorsa, Sofia; Valls Ferrer, Juan Antonio; van der Graaf, Harry; van der Kraaij, Erik; Van Der Leeuw, Robin; van der Poel, Egge; van der Ster, Daniel; van Eldik, Niels; van Gemmeren, Peter; van Vulpen, Ivo; Vanadia, Marco; Vandelli, Wainer; Vaniachine, Alexandre; Vankov, Peter; Vannucci, Francois; Vari, Riccardo; Varol, Tulin; Varouchas, Dimitris; Vartapetian, Armen; Varvell, Kevin; Vassilakopoulos, Vassilios; Vazeille, Francois; Vazquez Schroeder, Tamara; Vegni, Guido; Veillet, Jean-Jacques; Veloso, Filipe; Veness, Raymond; Veneziano, Stefano; Ventura, Andrea; Ventura, Daniel; Venturi, Manuela; Venturi, Nicola; Vercesi, Valerio; Verducci, Monica; Verkerke, Wouter; Vermeulen, Jos; Vest, Anja; Vetterli, Michel; Vichou, Irene; Vickey, Trevor; Vickey Boeriu, Oana Elena; Viehhauser, Georg; Viel, Simon; Villa, Mauro; Villaplana Perez, Miguel; Vilucchi, Elisabetta; Vincter, Manuella; Vinek, Elisabeth; Vinogradov, Vladimir; Virchaux, Marc; Virzi, Joseph; Vitells, Ofer; Viti, Michele; Vivarelli, Iacopo; Vives Vaque, Francesc; Vlachos, Sotirios; Vladoiu, Dan; Vlasak, Michal; Vogel, Adrian; Vokac, Petr; Volpi, Guido; Volpi, Matteo; Volpini, Giovanni; von der Schmitt, Hans; von Loeben, Joerg; von Radziewski, Holger; von Toerne, Eckhard; Vorobel, Vit; Vorwerk, Volker; Vos, Marcel; Voss, Rudiger; Voss, Thorsten Tobias; Vossebeld, Joost; Vranjes, Nenad; Vranjes Milosavljevic, Marija; Vrba, Vaclav; Vreeswijk, Marcel; Vu Anh, Tuan; Vuillermet, Raphael; Vukotic, Ilija; Wagner, Wolfgang; Wagner, Peter; Wahlen, Helmut; Wahrmund, Sebastian; Wakabayashi, Jun; Walch, Shannon; Walder, James; Walker, Rodney; Walkowiak, Wolfgang; Wall, Richard; Waller, Peter; Wang, Chiho; Wang, Haichen; Wang, Hulin; Wang, Jike; Wang, Jin; Wang, Rui; Wang, Song-Ming; Wang, Tan; Warburton, Andreas; Ward, Patricia; Warsinsky, Markus; Washbrook, Andrew; Wasicki, Christoph; Watkins, Peter; Watson, Alan; Watson, Ian; Watson, Miriam; Watts, Gordon; Watts, Stephen; Waugh, Anthony; Waugh, Ben; Weber, Marc; Weber, Michele; Weber, Pavel; Weidberg, Anthony; Weigell, Philipp; Weingarten, Jens; Weiser, Christian; Wellenstein, Hermann; Wells, Phillippa; Wenaus, Torre; Wendland, Dennis; Weng, Zhili; Wengler, Thorsten; Wenig, Siegfried; Wermes, Norbert; Werner, Matthias; Werner, Per; Werth, Michael; Wessels, Martin; Wetter, Jeffrey; Weydert, Carole; Whalen, Kathleen; Wheeler-Ellis, Sarah Jane; White, Andrew; White, Martin; White, Sebastian; Whitehead, Samuel Robert; Whiteson, Daniel; Whittington, Denver; Wicek, Francois; Wicke, Daniel; Wickens, Fred; Wiedenmann, Werner; Wielers, Monika; Wienemann, Peter; Wiglesworth, Craig; Wiik-Fuchs, Liv Antje Mari; Wijeratne, Peter Alexander; Wildauer, Andreas; Wildt, Martin Andre; Wilhelm, Ivan; Wilkens, Henric George; Will, Jonas Zacharias; Williams, Eric; Williams, Hugh; Willis, William; Willocq, Stephane; Wilson, John; Wilson, Michael Galante; Wilson, Alan; Wingerter-Seez, Isabelle; Winkelmann, Stefan; Winklmeier, Frank; Wittgen, Matthias; Wolter, Marcin Wladyslaw; Wolters, Helmut; Wong, Wei-Cheng; Wooden, Gemma; Wosiek, Barbara; Wotschack, Jorg; Woudstra, Martin; Wozniak, Krzysztof; Wraight, Kenneth; Wright, Catherine; Wright, Michael; Wrona, Bozydar; Wu, Sau Lan; Wu, Xin; Wu, Yusheng; Wulf, Evan; Wynne, Benjamin; Xella, Stefania; Xiao, Meng; Xie, Song; Xu, Chao; Xu, Da; Yabsley, Bruce; Yacoob, Sahal; Yamada, Miho; Yamaguchi, Hiroshi; Yamamoto, Akira; Yamamoto, Kyoko; Yamamoto, Shimpei; Yamamura, Taiki; Yamanaka, Takashi; Yamaoka, Jared; Yamazaki, Takayuki; Yamazaki, Yuji; Yan, Zhen; Yang, Haijun; Yang, Un-Ki; Yang, Yi; Yang, Zhaoyu; Yanush, Serguei; Yao, Liwen; Yao, Yushu; Yasu, Yoshiji; Ybeles Smit, Gabriel Valentijn; Ye, Jingbo; Ye, Shuwei; Yilmaz, Metin; Yoosoofmiya, Reza; Yorita, Kohei; Yoshida, Riktura; Young, Charles; Young, Christopher John; Youssef, Saul; Yu, Dantong; Yu, Jaehoon; Yu, Jie; Yuan, Li; Yurkewicz, Adam; Zabinski, Bartlomiej; Zaidan, Remi; Zaitsev, Alexander; Zajacova, Zuzana; Zanello, Lucia; Zaytsev, Alexander; Zeitnitz, Christian; Zeman, Martin; Zemla, Andrzej; Zendler, Carolin; Zenin, Oleg; Ženiš, Tibor; Zinonos, Zinonas; Zenz, Seth; Zerwas, Dirk; Zevi della Porta, Giovanni; Zhan, Zhichao; Zhang, Dongliang; Zhang, Huaqiao; Zhang, Jinlong; Zhang, Xueyao; Zhang, Zhiqing; Zhao, Long; Zhao, Tianchi; Zhao, Zhengguo; Zhemchugov, Alexey; Zhong, Jiahang; Zhou, Bing; Zhou, Ning; Zhou, Yue; Zhu, Cheng Guang; Zhu, Hongbo; Zhu, Junjie; Zhu, Yingchun; Zhuang, Xuai; Zhuravlov, Vadym; Zieminska, Daria; Zimmermann, Robert; Zimmermann, Simone; Zimmermann, Stephanie; Ziolkowski, Michael; Zitoun, Robert; Živković, Lidija; Zmouchko, Viatcheslav; Zobernig, Georg; Zoccoli, Antonio; zur Nedden, Martin; Zutshi, Vishnu; Zwalinski, Lukasz

    2012-01-01

    Distributions sensitive to the underlying event are studied in events containing one or more charged-particle jets produced in pp collisions at $\\sqrt{s}$ = 7 TeV with the ATLAS detector at the Large Hadron Collider (LHC). These measurements reflect 800 inverse microbarns of data taken during 2010. Jets are reconstructed using the anti-$k_t$ algorithm with radius parameter R varying between 0.2 and 1.0. Distributions of the charged-particle multiplicity, the scalar sum of the transverse momentum of charged particles, and the average charged-particle pT are measured as functions of $p_T^{JET}$ in regions transverse to and opposite the leading jet for 4 GeV < $p_T^{JET}$ < 100 GeV. In addition, the R-dependence of the mean values of these observables is studied. In the transverse region, both the multiplicity and the scalar sum of the transverse momentum at fixed $p_T^{JET}$ vary significantly with R, while the average charged-particle transverse momentum has a minimal dependence on R. Predictions from se...

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

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

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

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

    OpenAIRE

    Wolansky, Gershon

    2006-01-01

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

  18. Evaluation of aerosol sizing characteristic of an impactor using imaging plate technique.

    Science.gov (United States)

    Rahman, Naureen Mahbub; Iida, Takao; Saito, Fumihiro; Koarashi, Jun; Yamasaki, Keizou; Yamazawa, Hiromi; Moriizumi, Jun

    2007-01-01

    The activity-size distribution of radon decay products are normally determined using two approaches: direct and indirect. The present study utilises the direct approach to evaluate sizing information of a low pressure cascade impactor using imaging plate (IP) technique for radon decay products. The experiment verified the use of the collection media as suggested by the manufacturer of impactor and proposed a few improvements toward sizing characteristics of impactor. The obtained relative activity-size distribution of radon decay products presents a sharp unimodal log-normal distribution of the particle characterised by activity median aerodynamic diameter (AMAD) of 268 nm and geometric standard deviation (sigma(g)) of 1.66. The obtained data with all the suggested improvements were evaluated by the data obtained from a scanning mobility particle sizer (SMPS, Model 3934, TSI Inc), as reference data. The verification lead to a derivative area ratio of 0.803 between the reference and experimental data. PMID:16936289

  19. Particle size tuning in silver-polyacrylonitrile nanocomposites

    Directory of Open Access Journals (Sweden)

    2010-02-01

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

  20. Taille des particules et catalyse Particle Size and Catalysis

    Directory of Open Access Journals (Sweden)

    Boitiaux J. P.

    2006-11-01

    relationship between the catalyst characteristics and their reaction properties has helped in some situations to make a virtually atomic description of the specific active site of each reaction. The various authors have all taken a different approach to the problem. One approach considered the crystallographic properties of the mass metals, while another considered that small particles have neither the properties nor the structure of the mass metal. The crystallographic approach first led to the consideration of the crystal parameters and to a distinction between the different atoms located at the corners, kinks and faces. However, it was found very soon that the particles did not have the expected structures. It then became necessary to calculate the energy of the particles considered to identify the way in which they could grow from a small nucleus. These calculations considered neither the atmosphere in contact with the particle, no the presence of a support, nor the disturbances caused by the reaction. Depending on the reaction investigated, 'easy' reactions, unaffected by the structure, were distinguished from 'demanding' reactions, of which the intrinsic rate varies with the surface structure. Many investigations were conducted on monocrystals, whose exposed surfaces had difference indexes, and others attempted to analyze these relationships with supported metals, with all the artefacts that this could imply. It was difficult to find any unity in the overall results obtained, especially since self-poisoning by the reactants (hydrocarbons or hydrogen could readily explain the mechanisms observed. Moreover, a metal deposited on silica and the same metal deposited on alumina can display completely different behavior. This shows that some interpretations are too simplistic, and that it is inadequate to vary the particle size by any available means and to analyze the consequences on the catalytic process. The two complementary approaches, that of the crystallographer, who

  1. PENGARUH UKURAN PARTIKEL DAN PROPORSI GULURONAT/MANURONAT DALAM ALGINAT TERHADAP SIFAT DAN SENSORIS PRODUK HASIL RESTRUKTURISASI DARI BUAH SIRSAK [The Influence of Particle size and Guluronic/Mannuronic Proportion of Alginate on Physical and Sensory Characteristics of Restructured Products from Soursop

    Directory of Open Access Journals (Sweden)

    Sri Raharjo

    2003-12-01

    Full Text Available The application of restructuring technology is intended to add value for local fruits. Fresh and ripe sour sop fruits are frequently of having defective appearance, irregular shape and size, or showing signs of insect infestation which make the whole fruit is less acceptable by consumers. Previous study has indicated that sour sop fruit can be restructured into a fresh fruit product with acceptable sensory characteristics using calcium alginate gel system. This particular study was intended to determine the effect of alginate powder particles size and its guluronic/mannuronic proportion on the physical and sensorial properties of restructured sour sop. The restructured fruit product was evaluated based on its gel strength, pH colour, and sensory attributes which include taste, aroma, mouth feel, appearance, and hardness. Sour sop restructured by internal setting with coarse alginate powder (36 mesh tend to have softer gel compared to the use of fine alginate powder (120 mesh. Different proportion of guluronic/mannuronic in the alginate used for the restructurization resulted in the same gel strength when calcium lactate powder was used. However, the use of encapsulated calcium lactate resulted in stronger gel with alginate containing higher proportion of mannuronic acid. The alginate particle size and proportion of guluronic/mannuronic content showed no significant difference in product colour and sensory attributes evaluated.

  2. Number size distributions and seasonality of submicron particles in Europe 2008-2009

    Science.gov (United States)

    Asmi, A.; Wiedensohler, A.; Laj, P.; Fjaeraa, A.-M.; Sellegri, K.; Birmili, W.; Weingartner, E.; Baltensperger, U.; Zdimal, V.; Zikova, N.; Putaud, J.-P.; Marinoni, A.; Tunved, P.; Hansson, H.-C.; Fiebig, M.; Kivekäs, N.; Lihavainen, H.; Asmi, E.; Ulevicius, V.; Aalto, P. P.; Swietlicki, E.; Kristensson, A.; Mihalopoulos, N.; Kalivitis, N.; Kalapov, I.; Kiss, G.; de Leeuw, G.; Henzing, B.; Harrison, R. M.; Beddows, D.; O'Dowd, C.; Jennings, S. G.; Flentje, H.; Weinhold, K.; Meinhardt, F.; Ries, L.; Kulmala, M.

    2011-06-01

    Two years of harmonized aerosol number size distribution data from 24 European field monitoring sites have been analysed. The results give a comprehensive overview of the European near surface aerosol particle number concentrations and number size distributions between 30 and 500 nm of dry particle diameter. Spatial and temporal distribution of aerosols in the particle sizes most important for climate applications are presented. We also analyse the annual, weekly and diurnal cycles of the aerosol number concentrations, provide log-normal fitting parameters for median number size distributions, and give guidance notes for data users. Emphasis is placed on the usability of results within the aerosol modelling community. We also show that the aerosol number concentrations of Aitken and accumulation mode particles (with 100 nm dry diameter as a cut-off between modes) are related, although there is significant variation in the ratios of the modal number concentrations. Different aerosol and station types are distinguished from this data and this methodology has potential for further categorization of stations aerosol number size distribution types. The European submicron aerosol was divided into characteristic types: Central European aerosol, characterized by single mode median size distributions, unimodal number concentration histograms and low variability in CCN-sized aerosol number concentrations; Nordic aerosol with low number concentrations, although showing pronounced seasonal variation of especially Aitken mode particles; Mountain sites (altitude over 1000 m a.s.l.) with a strong seasonal cycle in aerosol number concentrations, high variability, and very low median number concentrations. Southern and Western European regions had fewer stations, which decreases the regional coverage of these results. Aerosol number concentrations over the Britain and Ireland had very high variance and there are indications of mixed air masses from several source regions; the

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

    Science.gov (United States)

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

    2015-06-18

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

  4. Gas/particle flow characteristics of two swirl burners

    International Nuclear Information System (INIS)

    A three-component particle-dynamics anemometer is used to measure, in the near-burner region, the characteristics of gas/particle two-phase flows with a centrally fuel rich swirl coal combustion burner and enhanced ignition-dual register burner, on a gas/particle two-phase test facility. Velocities, RMS velocities, particle mean diameters and particle volume flux profiles were obtained. For the centrally fuel rich burner, particles penetrate the central recirculation zone partially, and are then deflected radially. For the enhanced ignition-dual register burner, particles completely penetrate the central recirculation zone. Compared with the enhanced ignition-dual register burner, in the same cross-section, the particle volume flux peak value for the centrally fuel rich burner is much closer to the chamber axis and much larger near the chamber axis. In six cross-sections from x/d = 0.3 to 2.5, the particle volume flux in the central recirculation zone for the centrally fuel rich burner is much larger than that for the enhanced ignition-dual register burner. For the centrally fuel rich burner, most of bigger particles are resident in the region near the chamber axis and the residence time is prolonged. The influence of gas/particle flow characteristics on combustion has been analyzed.

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

    Institute of Scientific and Technical Information of China (English)

    TAI Feng; GUO Fu

    2009-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  9. Linking Particle and Pore-Size Distribution Parameters to Soil Gas Transport Properties

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Møldrup, Per; Schjønning, Per;

    2012-01-01

    topsoil of two Danish arable fields representing two natural clay gradients, Dp/Do and ka were measured at soil water matric potentials between −1 and −100 kPa on undisturbed soil cores. The Rosin–Rammler particle size distribution parameters α and β (characteristic particle size and degree of sorting......, respectively) and the Campbell water retention parameter b were used to characterize particle and pore size distributions, respectively. Campbell b yielded a wide interval (4.6–26.2) and was highly correlated with α, β, and volumetric clay content. Both Dp/Do and ka followed simple power-law functions (PLFs......) of air-filled porosity (εa). The PLF tortuosity–connectivity factors (X*) for Dp/Do and ka were both highly correlated with all basic soil characteristics, in the order of volumetric clay content = Campbell b > gravimetric clay content > α > β. The PLF water blockage factors (H) for Dp/Do and ka were...

  10. Aerosol size distribution characteristics of organosulfates in the Pearl River Delta region, China

    Science.gov (United States)

    Kuang, Bin Yu; Lin, Peng; Hu, Min; Yu, Jian Zhen

    2016-04-01

    Organosulfates (OSs) have been detected in various atmospheric environments, but their particle size distribution characteristics are unknown. In this work, we examined their size distributions in ambient aerosols to gain insights into the formation processes. Size-segregated aerosol samples in the range of 0.056-18 μm were collected using a ten-stage impactor at a receptor site in Hong Kong in both summer and winter and in Nansha in the Pearl River Delta in winter. The humic-like substances fraction in the size-segregated samples was isolated and analyzed using electrospray ionization coupled with an Orbitrap Ultra High Resolution Mass Spectrometer. Through accurate mass measurements, ∼190 CHOS and ∼90 CHONS formulas were tentatively identified to be OS compounds. Among them, OS compounds derived from isoprene, α-/β-pinene, and limonene and alkyl OSs having low double bond equivalents (DBE = 0,1) and 0-2 extra O beyond those in -OSO3 were found with high intensity. The biogenic volatile organic compounds-derived OS formulas share a common characteristic with sulfate in that the droplet mode dominated, peaking in either 0.56-1.0 or 1.0-1.8 μm size bin, reflecting sulfate as their common precursor. Most of these OSs have a minor coarse mode, accounting for 0-45%. The presence of OSs on the coarse particles is hypothesized to be a result of OSs on small particle (OS to non-sea-salt sulfate present on the coarse particles were similar to those on particles OS compounds have a dominant droplet mode at the Hong Kong site, but a more significant coarse mode presence was observed for CnH2n+1O4S-, CnH2n-1O4S-, and CnH2n-1O5S- formulas in the Nansha site, possibly suggesting site-specific mixed secondary and primary sources for these formulas.

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

    This study investigated the emission characteristics of ultrafine particles based on test bench and on-board measurements.The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of (0.56-8.35) × 108 cm-3.The on-board measurement results illustrated that the ultrafine particles were strongly correlated with changes in real-world driving cycles.The particle number concentration was down to 2.0 × 106 cm-3 and 2.7 × 107 cm-3 under decelerating and idling operations and as high as 5.0 × 108 cm-3 under accelerating operation.It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases.The particle number presented a "U" shaped distribution with changing speed at high engine load conditions,which implies that the particle number will reach its lowest level at medium engine speeds.The particle sizes of both measurements showed single mode distributions.The peak of particle size was located at about 50-80 nm in the accumulation mode particle range.Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.

  13. Effect of particle size, air flow and inhaler device on the aerosolisation of disodium cromoglycate powders.

    Science.gov (United States)

    Chew, N Y; Bagster, D F; Chan, H K

    2000-09-25

    Recently, the dispersion of mannitol powders has demonstrated the importance of particle size, air flow and inhaler device (Chew and Chan, 1999). The aim of the present study is to extend our investigation to a different compound, disodium cromoglycate (DSCG) powders. Solid state characteristics of the powders were assessed by particle sizing, scanning electron microscopy, X-ray powder diffraction, moisture content, particle density determination and freeze fracture. The aerosol behaviour of the powders was studied by dispersion using Rotahaler(R) and Dinkihaler(R), connected to a four-stage liquid impinger operating at 30-120 l/min. Three amorphous powders with a mass median diameter (MMD) of 2.3, 3.7, 5.2 microm and a similar polydispersity were prepared. The particles were nearly spherical with a particle density of 1.6 g/cm(3) and moisture content of 6.6 wt.%. Using Rotahaler(R), the maximum fine particle fraction (FPF(max)) for all three powders was only 15 wt.%, attained at the highest flow of 120 l/min. Using Dinkihaler(R), the FPF(max) was two to four times higher, being 36 and 29 wt.% for the 2.3 and 3.7 microm powder, respectively, at 60 l/min; and 18 wt.% for the 5.2 microm powder at 120 l/min. Hence, the study shows that the FPF in the DSCG powder aerosols was determined by the interaction of the particle size, air flow and inhaler design. The attribution of the amorphous nature and the different physico-chemical properties of the powder may explain the incomplete and low dispersibility of DSCG. PMID:11058812

  14. Relationship between hydraulic conductivity and formation factor of coarse-grained soils as a function of particle size

    Science.gov (United States)

    Choo, H.; Kim, J.; Lee, W.; Lee, C.

    2016-04-01

    This theoretical and experimental study investigates the variations of both the hydraulic conductivity and the electrical conductivity of coarse-grained soils as a function of pore water conductivity, porosity, and median particle size, with the ultimate goal of developing the relationship between the hydraulic conductivity (K) and the formation factor (F) in coarse-grained soils as a function of particle size. To monitor the variations of both the hydraulic conductivity and electrical conductivity (formation factor) of six sands with varying particle sizes, a series of hydraulic conductivity tests were conducted using a modified constant head permeameter equipped with a four electrode resistivity probe. It is demonstrated that K of the tested coarse-grained soils is mainly determined by the porosity and particle size. In contrast, the effect of particle size on the measured electrical conductivity (or F) is negligible, and the variation of F of the tested soils is mainly determined by porosity. Because the porosity may act as a connecting characteristic between K and F, the relation between them in coarse-grained soils can be expressed as a function of particle size. Finally, simple charts are developed for estimating the hydraulic conductivity of coarse-grained soils from the measured particle sizes and formations factors.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-02

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

  16. 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.

  17. Drilling coal seam outbursts where particle size matters

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-10-01

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

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

    CERN Document Server

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

    2014-01-01

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

  19. Effects of particle size and surrounding media on optical radiation efficiencies of spherical plasmonic metal nanoparticles

    Indian Academy of Sciences (India)

    Vinayak A Dhumale; Preeti V Shah; Rishi B Sharma; Katsuaki Tanabe

    2012-04-01

    The optical radiation efficiency (), the ratio of scattering cross-section to extinction cross-section, of spherical metal nanoparticles (M= Al, Ag, Au and Cu) surrounded by glass and water was calculated using classical electrostatics. The effect of varying particle diameter (∼100 nm) on was also studied for free space wavelengths in the range of 400–1200 nm. The variations in the value of with the diameter () of the metal nanoparticles were calculated on the basis of quasi-static approximation. The increases with the size of metal nanoparticles. Corresponding to a metal nanoparticle, was found to exhibit a sharp dip (dip) at a characteristic wavelength ()M in a particular medium ( = air, glass and water). ()M was independent of particle size. The (medium)M was found to be slightly blue shifted for all metal nanoparticles surrounded by glass or water with respect to those in the air.

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

    OpenAIRE

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

    2010-01-01

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

  1. Effect of lower grain sized particles on natural radiation level of the Ponnaiyar river sediments

    International Nuclear Information System (INIS)

    River sediment depositions on the bottom of rivers most frequently consist of sand and gravel particles with different grain sizes, which make them particularly valuable for the building construction. Knowledge of radioactivity present in building material enables one to assess any possible radiological hazard to mankind by the use of such materials. The natural radionuclide (238U, 232Th and 40K) contents have been analyzed for the sediment samples of Ponnaiyar River with an aim of evaluating the radiation hazard nature. To know the radiological characteristics of the sediment, dose rate is calculated and are compared with recommended values. Mineral characteristics of the sediments have been analyzed through FTIR and XRD techniques. Extinction coefficient and Crystallinity index is calculated to know the relative distribution of major minerals and crystalline nature of quartz, respectively. Multivariate statistical analyses were carried to find the relationship between the radioactivity characteristics and minerals, the results obtained in the study suggest that the level of natural radioactivity of the present sediments mainly depends upon the amount of kaolinite (clay). Mineral characterization of various grain sized sediments show clay and magnetic minerals are rich in lower grain sized (≤120 μm) samples. The level of radioactivity has also been measured for >120 μm sediments and results show that both activity concentrations and dose rate are considerably lowered when compared with the respective values of the bulk samples. The removal of ≤120 μm particles from the sediments of the river make it safer to use these materials for building construction. - Highlights: ► River sediment natural radioactivity mainly depends upon kaolinite (clay). ► Minerals in various grain sized sediments have been characterized. ► Radioactivity of >120 μm grain sized sediments considerably decrease. ► Removal of ≤120 μm grain sized sediments may be safer for

  2. Identifying the relation between trapping force of Laser Tweezers and Size of Microsphere particles

    Science.gov (United States)

    Diabre, Alexandra

    Optical trapping technique is the method in which micron and sub-micron particles can be studied. In this technique the laser pressure radiation creates the essential force to trap particles. This force depends on several parameters including the particles' indices of refraction, the specification of the beads surrounding environment and the characteristics of the implemented laser. On this work we present the outcome of the experiment we designed to analyze the trapping force. In this experiment we used micro sized beads with different indices of refraction, changed the viscosity of the surrounding environment of the beads and adjusted the power of the laser implemented. By analyzing the motion of the beads in several trials, the trapping force was estimated and its dependency to the parameters mentioned above was identified. Finally the outcomes of our experiment were compared with the theoretical reported results. This work was conducted under the supervision by Dr. Mitra Feizabadi.

  3. Characteristics of sediment particle size and their response to storm surge in the Zhanjiang Mangrove Nature Reserve%湛江红树林保护区现代沉积物粒度特征及其对风暴事件的响应

    Institute of Scientific and Technical Information of China (English)

    许艳; 王拓夫

    2011-01-01

    Mangrove forest sediment in different landforms reflects different hydrodynamic conditions because of the different sedimentary environments and different sediment particle size characteristics. Mangroves in different stages of development have different ability to resist the effects of waves; therefore, there are mangrove sedimentary records of storm surge. There has been little research on the particle size characteristics of mangrove sediment in coastal wetlands. In this work, surface sediment samples were collected in the Zhanjiang Mangrove National Nature Reserve in August, 2009, and then analyzed using a Mastersizer 2000 ( analysis range of 0.02 to 2 000 μm).The Zhanjiang Mangrove National Nature Reserve has a wide mangrove distribution; in this study, different geomorphic units of mangrove sediment particle size characteristics are analyzed. The mangrove sediment in the estuary is mainly composed of well-sorted silt and clay. The mangrove sediment in the bay is mainly composed of silt,but a sediment section at the Gaoqiao sampling site has high sand content. There are two possible reasons for this:one is that the region experienced a strong storm surge disaster in that period of sedimentation, which resulted in an instant rise in the water level and brought much coarse sand to be accumulated; and the other is that the region at that time was unvegetated beach in an intertidal zone without mangrove protection or with only poorly developed mangrove protection, and the sediment is normal tidal flat sand. Different particle grades and changes in clay, silt and sand contents at the Tongming sampling site can reflect the history of local sangrove development. Dating sediment using the average deposition rate can indicate the approximate time that the storm surge occurred and provide an important theoretical foundation and method for systematic research on sediment in the mangrove wetlands. Analysis shows that from 1963 to 2002, the timing of the storm surge is

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2011-07-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  8. Nanoparticle diffusion within intestinal mucus: Three-dimensional response analysis dissecting the impact of particle surface charge, size and heterogeneity across polyelectrolyte, pegylated and viral particles.

    Science.gov (United States)

    Abdulkarim, Muthanna; Agulló, Nuria; Cattoz, Beatrice; Griffiths, Peter; Bernkop-Schnürch, Andreas; Borros, Salvador Gómez; Gumbleton, Mark

    2015-11-01

    Multiple particle tracking (MPT) methodology was used to dissect the impact of nanoparticle surface charge and size upon particle diffusion through freshly harvested porcine jejunum mucus. The mucus was characterised rheologically and by atomic force microscopy. To vary nanoparticle surface charge we used a series of self-assembly polyelectrolyte particles composed of varying ratios of the negatively charged polyacrylic acid polymer and the positively charged chitosan polymer. This series included a neutral or near-neutral particle to correspond to highly charged but near-neutral viral particles that appear to effectively permeate mucus. In order to negate the confounding issue of self-aggregation of such neutral synthetic particles a sonication step effectively reduced particle size (to less than 340 nm) for a sufficient period to conduct the tracking experiments. Across the polyelectrolyte particles a broad and meaningful relationship was observed between particle diffusion in mucus (×1000 difference between slowest and fastest particle types), particle size (104-373 nm) and particle surface charge (-29 mV to +19.5 mV), where the beneficial characteristic promoting diffusion was a neutral or near-neutral charge. The diffusion of the neutral polyelectrolyte particle (0.02887 cm S(-1)×10(-9)) compared favourably with that of a highly diffusive PEGylated-PLGA particle (0.03182 cm(2) S(-1)×10(-9)), despite the size of the latter (54 nm diameter) accommodating a reduced steric hindrance with the mucin network. Heterogeneity of particle diffusion within a given particle type revealed the most diffusive 10% sub-population for the neutral polyelectrolyte formulation (5.809 cm(2) S(-1)×10(-9)) to be faster than that of the most diffusive 10% sub-populations obtained either for the PEGylated-PLGA particle (4.061 cm(2) S(-1)×10(-9)) or for a capsid adenovirus particle (1.922 cm(2) S(-1)×10(-9)). While this study has used a simple self-assembly polyelectrolyte system

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

    Science.gov (United States)

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

    2014-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2014-09-01

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

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

    Science.gov (United States)

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

    2015-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Cliver, E. W. [Space Vehicles Directorate, Air Force Research Laboratory, Sunspot, NM 88349 (United States); Ling, A. G. [Atmospheric Environmental Research, Lexington, MA 02421 (United States); Belov, A. [IZMIRAN, Troitsk, Moscow Region 142190 (Russian Federation); Yashiro, S. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-09-10

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast ({>=}1000 km s{sup -1}) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes ({alpha} values) of power-law size distributions of the peak 1-8 A fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes {>=}1 pr cm{sup -2} s{sup -1} sr{sup -1}) and (b) fast CMEs were {approx}1.3-1.4 compared to {approx}1.2 for the peak proton fluxes of >10 MeV SEP events and {approx}2 for the peak 1-8 A fluxes of all SXR flares. The difference of {approx}0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

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

    International Nuclear Information System (INIS)

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (≥1000 km s–1) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (α values) of power-law size distributions of the peak 1-8 Å fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes ≥1 pr cm–2 s–1 sr–1) and (b) fast CMEs were ∼1.3-1.4 compared to ∼1.2 for the peak proton fluxes of >10 MeV SEP events and ∼2 for the peak 1-8 Å fluxes of all SXR flares. The difference of ∼0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  15. ESTIMATING SOIL PARTICLE-SIZE DISTRIBUTION FOR SICILIAN SOILS

    Directory of Open Access Journals (Sweden)

    Vincenzo Bagarello

    2009-09-01

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

  16. Radiological dispersal device outdoor simulation test: Cesium chloride particle characteristics

    International Nuclear Information System (INIS)

    Particles were generated from the detonation of simulated radiological dispersal devices (RDDs) using non-radioactive CsCl powder and explosive C4. The physical and chemical properties of the resulting particles were characterized. Two RDD simulation tests were conducted at Lawrence Livermore National Laboratory: one of the simulated RDDs was positioned 1 m above a steel plate and the other was partially buried in soil. Particles were collected with filters at a distance of 150 m from the origin of the RDD device, and particle mass concentrations were monitored to identify the particle plume intensity using real time particle samplers. Particles collected on filters were analyzed via computer-controlled scanning electron microscopy coupled with energy dispersive X-ray spectrometry (CCSEM/EDX) to determine their size distribution, morphology, and chemical constituents. This analysis showed that particles generated by the detonation of explosives can be associated with other materials (e.g., soil) that are in close proximity to the RDD device and that the morphology and chemical makeup of the particles change depending on the interactions of the RDD device with the surrounding materials.

  17. Scattering and Absorption Properties of Polydisperse Wavelength-sized Particles Covered with Much Smaller Grains

    Science.gov (United States)

    Dlugach, Jana M.; Mishchenko, Michael I.; Mackowski, Daniel W.

    2012-01-01

    Using the results of direct, numerically exact computer solutions of the Maxwell equations, we analyze scattering and absorption characteristics of polydisperse compound particles in the form of wavelength-sized spheres covered with a large number of much smaller spherical grains.The results pertain to the complex refractive indices1.55 + i0.0003,1.55 + i0.3, and 3 + i0.1. We show that the optical effects of dusting wavelength-sized hosts by microscopic grains can vary depending on the number and size of the grains as well as on the complex refractive index. Our computations also demonstrate the high efficiency of the new superposition T-matrix code developed for use on distributed memory computer clusters.

  18. Physical and chemical characteristics of interplanetary dust particles

    International Nuclear Information System (INIS)

    For the first time, the micrometeoroid experiment on board of Helios allowed the measurement of physical and chemical characteristics of interplanetary dust particles between 0.3AU and 1AU solar distance. During the first 10 orbits of Helios 1,235 impacts of micrometeoroids have been detected. 83 particles have been registered by the ecliptic sensor and 152 by the south sensor. Most of the particles detected by the ecliptic sensor had masses 10-13g -10g and impacted the sensor from the apex direction. The particles observed by the south sensor had masses 10-15g -9g and impacted the sensor from all directions with a slightly enhanced flux from solar direction. The average impact speed of particles with masses 10-13g -10g was 15km/s. From 1AU to.3AU, the observed paritcle flux increased by a factor 5-10. The orbits of the registered particles are highly eccentric, e approx. >= 0.6, and some are hyperbolic. The mass spectra measured upon impact allow the classification of chondritic and iron-rich particles. Approx. 20% of the particles had low densities rho 3. On 4 particles, a positive electric charge has been observed. (orig.)

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

    Directory of Open Access Journals (Sweden)

    T. S. Kostadinov

    2015-05-01

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

  20. Effects of Particle Sizes on the Electromagnetic Property of Flaky FeSi Composites

    Institute of Scientific and Technical Information of China (English)

    Yonggang XU; Liming YUAN; Jun CAI; Jianlu LV; Deyuan ZHANG

    2013-01-01

    Flaky FeSi absorbents with different size ranges were fabricated by sintering after mechanical milling process.X-ray diffraction (XRD) was used to analyze the particle crystal grain structure.The complex permittivity and permeability of FeSi/paraffin composites were measured in frequency of 2-12 GHz using a vector network analyzer,and the DC electric conductivity was measured by the standard four-point contact method,then microwave reflection loss (RL) and shielding effectiveness (SE) were calculated.It was obtained that α-Fe appeared in the super-lattice diffraction peaks in XRD pattern.As the particles size decreased,the permittivity decreased due to the inferior microwave electrical conductivity and dielectric loss tangent,while the permeability increased due to the decrease of diameter-thickness ratio,which could be demonstrated in the comparison between the experiment and calculation results.When thickness is 1 mm,the composites with the smallest FeSi particles addition had a better absorbing property for the better impedance matching characteristic,and the minimum RL was-7.9 dB at 4.6 GHz.While the composites with larger FeSi particles addition had an excellent shielding property due to the higher permittivity,the SE value ranged from 15 dB to 30 dB at the frequency band.

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

    Science.gov (United States)

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

    2016-05-01

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

  2. Alterações nos atributos químicos de um Latossolo distroférrico decorrentes da granulometria e doses de calcário em sistemas plantio direto e convencional Changes of chemical soil characteristics due to doses and particle sizes of limestone in no-tillage and conventional systems

    Directory of Open Access Journals (Sweden)

    J. C. A. Mello

    2003-06-01

    represented the tillage system, the sub-plots represented particle sizes of limestone (large and small and sub-sub plots lime doses of 2; 4 and 6 t ha-1 (large limestone particles and 1.2; 2.4 and 3.6 t ha-1 (small limestone particles. The soil was sampled (at depths of 0-5, 5-10, 10-20 and 20-40 cm 1, 3 and 12 months after liming. Variance analysis did not detect a three-fold interaction among the factors. 12 months after surface liming, chemical soil characteristics were positively affected (0-5 and 5-10 cm in the no-tillage system, independent of particle size and doses. Even after more than three months, the fertilizer had a continuos strong effect, independent of the tillage system. Higher lime doses with large particle sizes provided a prolonged residual effect.

  3. Chemical Synthesis of Nano-Sized particles of Lead Oxide and their Characterization Studies

    CERN Document Server

    Alagar, M; Raja, A Kubera; 10.3923/jas.2012.398.401

    2012-01-01

    The quantum dots of semiconductor display novel and interesting phenomena that have not been in the bulk material. The color tunability is one of the most attractive characteristics in II-VI semiconductor nanoparticles such as CdS, ZnS, CdSe, ZnSe and PbO. In this work, the semiconductor lead oxide nanoparticles are prepared by chemical method. The average particle size, specific surface area, crystallinity index are estimated from XRD analysis. The structural, functional groups and optical characters are analyzed with using of SEM, FTIR and UV- Visible techniques. The optical band gap value has also been determined.

  4. Influence of the particle size of activated mineral carbon on the phenol and chlorophenol adsorption

    International Nuclear Information System (INIS)

    Water pollution by phenolic compounds is a problem that requires a solution since these phenolic compounds are not completely biodegradable, they accumulate through the food chains and they are quite toxic when enter in contact with living organisms. In human beings, ingestion or contact of the skin with this type of compounds produces irritation and damages mainly to the liver and kidneys. In fact, the Environmental Protection Agency of the United States (EPA assigned nine phenolic compounds among the 275 most toxic substances in 1991. Phenols are found in wastewater from agriculture and industry, because phenolic compounds are used as pesticides and in diverse industrial activities. The treatment of this type of water is not simple because they are generally composed of a mixture of residuals with different chemical nature A useful method for the removal of phenols is the adsorption by activated carbon, since this material has a great surface area and it can be regenerated. The adsorption process depends, among other factors, on the activated carbon characteristics. When they are modified, their capacity to remove pollutants from the water changes. The effect of activated carbon particle size on the removal of phenolic compounds has not been completely studied. Therefore, the aim of this work was to determine the influence of the mineral activated carbon particle size on the phenol and 4-chloro phenol adsorption in aqueous solution, on adsorption column system. The results of the present work indicate that the mineral activated carbon particle size has a very important influence on the adsorption of phenol and 4-chloro phenol. When the particles were smaller, the retention quantities of phenol and 4-chloro phenol increased. This behavior was related to the particle characteristics of the mineral activated carbon such as surface area and pore volume, while other factors such as elementary composition of the activated carbon did not influence the adsorption process

  5. Online Aerosol Mass Spectrometry of Single Micrometer-Sized Particles Containing Poly(ethylene glycol)

    Energy Technology Data Exchange (ETDEWEB)

    Bogan, M J; Patton, E; Srivastava, A; Martin, S; Fergenson, D; Steele, P; Tobias, H; Gard, E; Frank, M

    2006-10-25

    Analysis of poly(ethylene glycol)(PEG)-containing particles by online single particle aerosol mass spectrometers equipped with laser desorption ionization (LDI) is reported. We demonstrate that PEG-containing particles are useful in the development of aerosol mass spectrometers because of their ease of preparation, low cost, and inherently recognizable mass spectra. Solutions containing millimolar quantities of PEGs were nebulized and, after drying, the resultant micrometer-sized PEG containing particles were sampled. LDI (266 nm) of particles containing NaCl and PEG molecules of average molecular weight <500 generated mass spectra reminiscent of mass spectra of PEG collected by other MS schemes including the characteristic distribution of positive ions (Na{sup +} adducts) separated by the 44 Da of the ethylene oxide units separating each degree of polymerization. PEGs of average molecular weight >500 were detected from particles that also contained t the tripeptide tyrosine-tyrosine-tyrosine or 2,5-dihydroxybenzoic acid, which were added to nebulized solutions to act as matrices to assist LDI using pulsed 266 nm and 355 nm lasers, respectively. Experiments were performed on two aerosol mass spectrometers, one reflectron and one linear, that each utilize two time-of-flight mass analyzers to detect positive and negative ions created from a single particle. PEG-containing particles are currently being employed in the optimization of our bioaerosol mass spectrometers for the application of measurements of complex biological samples, including human effluents, and we recommend that the same strategies will be of great utility to the development of any online aerosol LDI mass spectrometer platform.

  6. Impacts of biochar concentration and particle size on hydraulic conductivity and DOC leaching of biochar-sand mixtures

    Science.gov (United States)

    Liu, Zuolin; Dugan, Brandon; Masiello, Caroline A.; Barnes, Rebecca T.; Gallagher, Morgan E.; Gonnermann, Helge

    2016-02-01

    The amendment of soil with biochar can sequester carbon and alter hydrologic properties by changing physical and chemical characteristics of soil. To understand the effect of biochar amendment on soil hydrology, we measured the hydraulic conductivity (K) of biochar-sand mixtures as well as dissolved organic carbon (DOC) in leachate. Specifically, we assessed the effects of biochar concentration and particle size on K and amount of DOC in the soil leachate. To better understand how physical properties influenced K, we also measured the skeletal density of biochars and sand, and the bulk density, the water saturation, and the porosity of biochar-sand mixtures. Our model soil was sand (0.251-0.853 mm) with biochar rates from 2 to 10 wt% (g biochar/g total soil × 100%). As biochar (biochar particle size was equal to, greater than, and less than particle size of sand, we found that biochar in different particle sizes have different effects on K. For a 2 wt% biochar rate, K decreased by 72 ± 2% when biochar particles were finer than sand particles, and decreased by 15 ± 2% when biochar particles were coarser than sand particles. When biochar and sand particle size were comparable, we observed no significant effect on K. We propose that the decrease of K through the addition of fine biochar was because finer biochar particles filled spaces between sand particles, which increased tortuosity and reduced pore throat size of the mixture. The decrease of K associated with coarser biochar was caused by the bimodal particle size distribution, resulting in more compact packing and increased tortuosity. The loss of biochar C as DOC was related to both biochar rate and particle size. The cumulative DOC loss was 1350% higher from 10 wt% biochar compared to pure sand. This large increase reflected the very small DOC yield from pure sand. In addition, DOC in the leachate decreased as biochar particle size increased. For all treatments, the fraction of carbon lost as DOC ranged from

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

    Science.gov (United States)

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

    2013-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

    Guanghui Ma

    2003-01-01

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

  10. Particle size and chemical phase distribution of plutonium in an estuarine sediment

    International Nuclear Information System (INIS)

    Plutonium in Lake Michigan sediments has been shown to be associated predominantly with hydrous oxides and exhibits an activity maximum in particles less than 4 μm in diameter. However, since plutonium exhibits variable size and charge characteristics in waters of differing ionic strength and chemical composition, an investigation was undertaken to determine if the particle size and chemical fraction distribution of plutonium in other sediments might be different. A sample of marine sediment was collected from 60 ft of water in Buzzard's Bay, Massachusetts, with sealed Smith-MacIntyre grab having a surface area of approximately 1 ft2. The loose floc layer overlying the consolidated sediment was removed by suction and was lyophylized. Three subsamples of the dry material were taken for determination of the ash/dry weight ratios and total 239240Pu concentration; sequential extraction to determine the distribution of plutonium among various chemical fractions of the sediment; and separation into five size classes by wet sieving and elutriation in a carbonate-oxalate dispersant, followed by the determination of the 239240Pu concentration in each size class. The results of the sequential extraction clearly indicate that most of the 239240Pu is found in the citrate-dithionite extract as is the case for Lake Michigan sediments

  11. Review: Bioanalytical applications of biomolecule-functionalized nanometer-sized doped silica particles

    International Nuclear Information System (INIS)

    Recent research has looked to develop innovative and powerful novel biofunctionalized nanometer-sized silica particles, controlling and tailoring their properties in a very predictable manner to meet the needs of specific applications. The silica shells of these particles facilitate a wide variety of surface reactions and allow conjugation with biomolecules like proteins and DNA. There exist a multitude of possible applications of fabricated nanoparticles in biotechnology and medicine. In particular, they have proved to be highly useful for biosensing, assay labelling, bioimaging, and in research on a variety of molecular tags in cellular and molecular biology. Techniques commonly rely on the use of silica-coated semiconductor quantum dots, organic dyes, magnetic particles, and Raman active particles. Inorganic-biological hybrid particles combine the properties of both materials, i.e., the spectroscopic characteristics of the entrapped nanocrystal, and the biomolecular function of the conjugated entity. Rather than being exhaustive, this review focuses on selected examples to illustrate novel concepts and promising applications. Approaches described include the encoding of silica nanoparticles with different groups, and conjugation with various biological entities. Further, promising applications in bioanalysis are considered and discussed.

  12. Pressure drops of single/two-phase flows through porous beds with multi-sizes spheres and sands particles

    International Nuclear Information System (INIS)

    Highlights: • Flow tests are performed in packed porous beds with multi-size spheres and sands. • Packed beds with similar size distributions have the similar effective particle diameters. • Reed model predicts well the pressure drop of two-phase flow through porous bed. - Abstract: This paper reports an experimental research of single and two-phase gas/liquid flow in packed porous beds composed of multi-sizes spheres and irregular particles. A test facility named DEBECO-LT is designed and constructed to investigate the friction laws of adiabatic single and two-phase flows in a porous bed. The results show that the effective diameter of multi-sizes non-spherical or irregular particles bed can be derived on the basis of bed consisted of spheres as long as they have a wide range of grain sizes and the similar size distribution. Given the effective particle diameter obtained from single-phase flow through the packed bed with multi-size spheres or irregular particles, the pressure drop of two-phase flow through the bed can be predicted by the Reed model. The experimental data provide insights for the flow characteristic of porous bed, as well as high-quality data for validation of the coolability analysis models and codes

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

    OpenAIRE

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

    2011-01-01

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

  14. PARTICLE SIZE ESTIMATION AND ELEMENTAL ANALYSIS OF LAUHA BHASMA

    Directory of Open Access Journals (Sweden)

    Singh Neetu

    2011-02-01

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

  15. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-22

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

  17. Laboratory Simulation of Impacts upon Aluminum Foils of the Stardust Spacecraft: Calibration of Dust Particle Size from Comet Wild 2

    Science.gov (United States)

    Kearsley, A. T.; Burchell, M. J.; Horz, F.; Cole, M. J.; Schwandt, C. S.

    2006-01-01

    Metallic aluminium alloy foils exposed on the forward, comet-facing surface of the aerogel tray on the Stardust spacecraft are likely to have been impacted by the same cometary particle population as the dedicated impact sensors and the aerogel collector. The ability of soft aluminium alloy to record hypervelocity impacts as bowl-shaped craters offers an opportunistic substrate for recognition of impacts by particles of a wide potential size range. In contrast to impact surveys conducted on samples from low Earth orbit, the simple encounter geometry for Stardust and Wild 2, with a known and constant spacecraft-particle relative velocity and effective surface-perpendicular impact trajectories, permits closely comparable simulation in laboratory experiments. For a detailed calibration programme we have selected a suite of spherical glass projectiles of uniform density and hardness characteristics, with well-documented particle size range from 10 microns to nearly 100 microns. Light gas gun buckshot firings of these particles at approximately 6km s)exp -1) onto samples of the same foil as employed on Stardust have yielded large numbers of craters. Scanning electron microscopy of both projectiles and impact features has allowed construction of a calibration plot, showing a linear relationship between impacting particle size and impact crater diameter. The close match between our experimental conditions and the Stardust mission encounter parameters should provide another opportunity to measure particle size distributions and fluxes close to the nucleus of Wild 2, independent of the active impact detector instruments aboard the Stardust spacecraft.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

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

    Science.gov (United States)

    Bai, Bing; Xu, Tao; Guo, Zhiguang

    2016-08-01

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

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

    Science.gov (United States)

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

    2013-05-01

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

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

    Science.gov (United States)

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

    2016-02-28

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

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

    Science.gov (United States)

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

    2006-02-01

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

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

    Science.gov (United States)

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

    2015-05-01

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

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

    Science.gov (United States)

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

    1985-01-01

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

  5. Effect of Different Coarse Aggregate Sizes on the Strength Characteristics of Laterized Concrete

    Science.gov (United States)

    Salau, M. A.; Busari, A. O.

    2015-11-01

    The high cost of conventional concrete materials is a major factor affecting housing delivery in developing countries such as Nigeria. Since Nigeria is blessed with abundant locally available materials like laterite, researchers have conducted comprehensive studies on the use of laterite to replace river sand partially or fully in the concrete. However, the works did not consider the optimum use of coarse aggregate to possibly improve the strength of the laterized concrete, since it is normally lower than that of normal concrete. The results of the tests showed that workability, density and compressive strength at constant water-cement ratio increase with the increase in the coarse aggregate particle size and also with curing age. As the percentage of laterite increases, there was a reduction in all these characteristics even with the particle size of coarse aggregate reduction due to loss from the aggregate-paste interface zone. Also, when sand was replaced by 25% of laterite, the 19.5mm and 12.5mm coarse aggregate particle sizes gave satisfactory results in terms of workability and compressive strength respectively at 28 days of curing age, compared to normal concrete. However, in case of 50% up to 100% laterite contents, the workability and compressive strength values were very low.

  6. 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...

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

    OpenAIRE

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

    2006-01-01

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

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

    Directory of Open Access Journals (Sweden)

    J. P. Fugal

    2009-03-01

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

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Michael J Dougherty

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

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

    Science.gov (United States)

    Pham, Ngoc; Papavassiliou, Dimitrios

    2015-11-01

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

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

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

    武作兵; 凌国灿; 邢启江

    2002-01-01

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

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

    International Nuclear Information System (INIS)

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

  15. 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.

  16. Determination of Size Distribution of Nano-particles by Capillary Zone Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Yan XUE; Hai Ying YANG; Yong Tan YANG

    2005-01-01

    A new method was developed for the determination of the size distribution of nano-particles by capillary zone electrophoresis (CZE). Scattering effect of nanoparticles was studied. This method for the determination of size distribution was statistical.

  17. Physicochemical characteristics and occupational exposure to coarse, fine and ultrafine particles during building refurbishment activities

    International Nuclear Information System (INIS)

    Understanding of the emissions of coarse (PM10 ≤10 μm), fine (PM2.5 ≤2.5 μm) and ultrafine particles (UFP <100 nm) from refurbishment activities and their dispersion into the nearby environment is of primary importance for developing efficient risk assessment and management strategies in the construction and demolition industry. This study investigates the release, occupational exposure and physicochemical properties of particulate matter, including UFPs, from over 20 different refurbishment activities occurring at an operational building site. Particles were measured in the 5–10,000-nm-size range using a fast response differential mobility spectrometer and a GRIMM particle spectrometer for 55 h over 8 days. The UFPs were found to account for >90 % of the total particle number concentrations and <10 % of the total mass concentrations released during the recorded activities. The highest UFP concentrations were 4860, 740, 650 and 500 times above the background value during wall-chasing, drilling, cementing and general demolition activities, respectively. Scanning electron microscopy, X-ray photoelectron spectroscopy and ion beam analysis were used to identify physicochemical characteristics of particles and attribute them to probable sources considering the size and the nature of the particles. The results confirm that refurbishment activities produce significant levels (both number and mass) of airborne particles, indicating a need to develop appropriate regulations for the control of occupational exposure of operatives undertaking building refurbishment.

  18. Physicochemical characteristics and occupational exposure to coarse, fine and ultrafine particles during building refurbishment activities

    Energy Technology Data Exchange (ETDEWEB)

    Azarmi, Farhad; Kumar, Prashant, E-mail: p.kumar@surrey.ac.uk, E-mail: prashant.kumar@cantab.net; Mulheron, Mike [University of Surrey, Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences (United Kingdom); Colaux, Julien L.; Jeynes, Chris [University of Surrey, Faculty of Engineering and Physical Sciences, Ion Beam Centre (United Kingdom); Adhami, Siavash; Watts, John F. [University of Surrey, The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences (United Kingdom)

    2015-08-15

    Understanding of the emissions of coarse (PM{sub 10} ≤10 μm), fine (PM{sub 2.5} ≤2.5 μm) and ultrafine particles (UFP <100 nm) from refurbishment activities and their dispersion into the nearby environment is of primary importance for developing efficient risk assessment and management strategies in the construction and demolition industry. This study investigates the release, occupational exposure and physicochemical properties of particulate matter, including UFPs, from over 20 different refurbishment activities occurring at an operational building site. Particles were measured in the 5–10,000-nm-size range using a fast response differential mobility spectrometer and a GRIMM particle spectrometer for 55 h over 8 days. The UFPs were found to account for >90 % of the total particle number concentrations and <10 % of the total mass concentrations released during the recorded activities. The highest UFP concentrations were 4860, 740, 650 and 500 times above the background value during wall-chasing, drilling, cementing and general demolition activities, respectively. Scanning electron microscopy, X-ray photoelectron spectroscopy and ion beam analysis were used to identify physicochemical characteristics of particles and attribute them to probable sources considering the size and the nature of the particles. The results confirm that refurbishment activities produce significant levels (both number and mass) of airborne particles, indicating a need to develop appropriate regulations for the control of occupational exposure of operatives undertaking building refurbishment.

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

    International Nuclear Information System (INIS)

    A numerical method is proposed for the characterization of core–shell spherical particles from static light scattering (SLS) measurements. The method is able to estimate the core size distribution (CSD) and the particle size distribution (PSD), through the following two-step procedure: (i) the estimation of the bivariate core–particle size distribution (C–PSD), by solving a linear ill-conditioned inverse problem through a generalized Tikhonov regularization strategy, and (ii) the calculation of the CSD and the PSD from the estimated C–PSD. First, the method was evaluated on the basis of several simulated examples, with polystyrene–poly(methyl methacrylate) core–shell particles of different CSDs and PSDs. Then, two samples of hematite–Yttrium basic carbonate core–shell particles were successfully characterized. In all analyzed examples, acceptable estimates of the PSD and the average diameter of the CSD were obtained. Based on the single-scattering Mie theory, the proposed method is an effective tool for characterizing core–shell colloidal particles larger than their Rayleigh limits without requiring any a-priori assumption on the shapes of the size distributions. Under such conditions, the PSDs can always be adequately estimated, while acceptable CSD estimates are obtained when the core/shell particles exhibit either a high optical contrast, or a moderate optical contrast but with a high ‘average core diameter’/‘average particle diameter’ ratio. -- Highlights: ► Particles with core–shell morphology are characterized by static light scattering. ► Core size distribution and particle size distribution are successfully estimated. ► Simulated and experimental examples are used to validate the numerical method. ► The positive effect of a large core/shell optical contrast is investigated. ► No a-priori assumption on the shapes of the size distributions is required.

  20. Mathematical model parameters for describing the particle size spectra of knife-milled corn stover

    Energy Technology Data Exchange (ETDEWEB)

    Bitra, V.S.P [University of Tennessee; Womac, A.R. [University of Tennessee; Yang, Y.T. [University of Tennessee; Miu, P.I. [University of Tennessee; Igathanathane, C. [Mississippi State University (MSU)

    2009-09-01

    Particle size distributions of Corn stover (Zea mays L.) created by a knife mill were determined using integral classifying screens with sizes from 12.7 to 50.8 mm, operating at speeds from 250 to 500 rpm, and mass input rates ranging from 1 to 9 kg min_1. Particle distributions were classified using American Society of Agricultural and Biological Engineers (ASABE) standardised sieves for forage analysis that incorporated a horizontal sieving motion. The sieves were made from machined-aluminium with their thickness proportional to the sieve opening dimensions. A wide range of analytical descriptors that could be used to mathematically represent the range of particle sizes in the distributions were examined. The correlation coefficients between geometric mean length and screen size, feed rate, and speed were 0.980, 0.612, and _0.027, respectively. Screen size and feed rate directly influenced particle size, whereas operating speed had a weak indirect relation with particle size. The Rosin Rammler equation fitted the chopped corn stover size distribution data with coefficient of determination (R2) > 0.978. This indicated that particle size distribution of corn stover was well-fit by the Rosin Rammler function. This can be attributed to the fact that Rosin Rammler expression was well suited to the skewed distribution of particle sizes. Skewed distributions occurred when significant quantities of particles, either finer or coarser, existed or were removed from region of the predominant size. The mass relative span was slightly greater than 1, which indicated that it was a borderline narrow to wide distribution of particle sizes. The uniformity coefficient was <4.0 for 19.0 50.8 mm screens, which indicated particles of relatively uniform size. Knife mill chopping of corn stover produced fine-skewed mesokurtic particles with 12.7 50.8 mm screens. Size-related parameters, namely, geometric mean length, Rosin Rammler size parameter, median length, effective length, and

  1. Characteristic size and mass of galaxies in the Bose-Einstein condensate dark matter model

    Science.gov (United States)

    Lee, Jae-Weon

    2016-05-01

    We study the characteristic length scale of galactic halos in the Bose-Einstein condensate (or scalar field) dark matter model. Considering the evolution of the density perturbation we show that the average background matter density determines the quantum Jeans mass and hence the spatial size of galaxies at a given epoch. In this model the minimum size of galaxies increases while the minimum mass of the galaxies decreases as the universe expands. The observed values of the mass and the size of the dwarf galaxies are successfully reproduced with the dark matter particle mass m ≃ 5 ×10-22 eV. The minimum size is about 6 ×10-3√{ m / H }λc and the typical rotation velocity of the dwarf galaxies is O (√{ H / m }) c, where H is the Hubble parameter and λc is the Compton wave length of the particle. We also suggest that ultra compact dwarf galaxies are the remnants of the dwarf galaxies formed in the early universe.

  2. Characteristic size and mass of galaxies in the Bose–Einstein condensate dark matter model

    Directory of Open Access Journals (Sweden)

    Jae-Weon Lee

    2016-05-01

    Full Text Available We study the characteristic length scale of galactic halos in the Bose–Einstein condensate (or scalar field dark matter model. Considering the evolution of the density perturbation we show that the average background matter density determines the quantum Jeans mass and hence the spatial size of galaxies at a given epoch. In this model the minimum size of galaxies increases while the minimum mass of the galaxies decreases as the universe expands. The observed values of the mass and the size of the dwarf galaxies are successfully reproduced with the dark matter particle mass m≃5×10−22 eV. The minimum size is about 6×10−3m/Hλc and the typical rotation velocity of the dwarf galaxies is O(H/m c, where H is the Hubble parameter and λc is the Compton wave length of the particle. We also suggest that ultra compact dwarf galaxies are the remnants of the dwarf galaxies formed in the early universe.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    Highlights: • Effects of fuel particle size distributions on neutron transport are evaluated. • Neutron channeling is identified as the fundamental reason for the effects. • The effects are noticeable at low packing and low optical thickness systems. • Unit cells of realistic reactor designs are studied for different size particles. • Fuel particle size distribution effects are not negligible in realistic designs. - Abstract: This paper presents a study of the fuel particle size distribution effects on neutron transport in three-dimensional stochastic media. Particle fuel is used in gas-cooled nuclear reactor designs and innovative light water reactor designs loaded with accident tolerant fuel. Due to the design requirements and fuel fabrication limits, the size of fuel particles may not be perfectly constant but instead follows a certain distribution. This brings a fundamental question to the radiation transport computation community: how does the fuel particle size distribution affect the neutron transport in particle fuel systems? To answer this question, size distribution effects and their physical interpretations are investigated by performing a series of neutron transport simulations at different fuel particle size distributions. An eigenvalue problem is simulated in a cylindrical container consisting of fissile fuel particles with five different size distributions: constant, uniform, power, exponential and Gaussian. A total of 15 parametric cases are constructed by altering the fissile particle volume packing fraction and its optical thickness, but keeping the mean chord length of the spherical fuel particle the same at different size distributions. The tallied effective multiplication factor (keff) and the spatial distribution of fission power density along axial and radial directions are compared between different size distributions. At low packing fraction and low optical thickness, the size distribution shows a noticeable effect on neutron

  5. Correlation between traffic density and particle size distribution in a street canyon and the dependence on wind direction

    Directory of Open Access Journals (Sweden)

    J. Voigtländer

    2006-05-01

    Full Text Available Combustion of fossil fuel in gasoline and diesel powered vehicles is a major source of aerosol particles in a city. In a street canyon, the number concentration of particles smaller than 300 nm in diameter, which can be inhaled and cause serious health effects, is dominated by particles originating from this source.

    In this study we measured both, particle number size distribution and traffic density continuously in a characteristic street canyon in Germany for a time period of 6 months. The street canyon with multistory buildings and 4 traffic lanes is very typical for larger cities. Thus, the measurements are also representative for many other street canyons. In contrast to previous studies, we measured and analyzed the particle number size distribution with high size resolution using a Twin Differential Mobility Analyzer (TDMPS. The measured size range was from 3 to 800 nm, separated into 40 size channels.

    Correlation coefficients between particle number concentration for integrated size ranges and traffic up to 0.5 counts were determined. Correlations were also calculated for each of the 40 size channels of the DMPS system, respectively. We found two maxima of the correlation coefficient for particles about 10 nm and in the size range 60–80 nm in diameter.

    Furthermore, correlations between traffic and particles in dependence of meteorological data were calculated. Relevant parameters were identified by a multiple regression method. In our experiment only wind parameters have influenced the particle number concentration significantly. Very high correlation coefficients (up to 0.85 could be observed in the lee side of the street canyon as well as particles in the range between 60 and 80 nm in diameter. These values are significantly higher than correlation coefficients for other wind directions and other particle sizes. A minimum was found in the luff side of the street. These findings are in good agreement

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

    Science.gov (United States)

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

    2016-01-01

    Understanding the geochemistry of basalt alteration is central to the study of agriculture systems. Various nano-minerals play an important role in the mobilization of contaminants and their subsequent uptake by plants. We present a new analytical experimental approach in combination with an integrated analytical protocol designed to study basalt alteration processes. Recently, throughout the world, ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been of great concern for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the Nova Prata mining district in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/Energy Dispersive Spectroscopy (EDS)/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM/EDS), and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3, and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition, we have identified a number of trace metals such as Cd, Cu, Cr, and Zn, that are preferentially concentrated into the finer, inhalable, dust fraction and, thus, could present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in

  7. Finite size fluid particle in nonuniform moving grid

    International Nuclear Information System (INIS)

    The particle-in-cell (PIC) method, which is known as mixed Eulerian-Lagrangian scheme, has been applied successfully to solve a wide variety of problems in which the fluid distortion is large. In this paper, a new type of the PIC method is presented. Area-weighting technique and a nonuniform-spacing, moving grid were employed for the suppression of nonphysical fluctuation and for the description of large density variation with few particles, respectively. The reduction of numerical viscosity is discussed. In a basic scheme, the equations for one compressible fluid were used. In the present approach to the PIC method, a particle has the memories for its own mass, position and internal energy, but momentum is attached to the particle only when it moves, in order to evade the multistreaming problem. An essential point is that a particle preserves the memory of the cell boundary lines when it moves. As the examples, one-dimensional adiabatic expansion process and the Rayleigh-Taylor instability were analyzed. The results showed that the new PIC method is useful for the description of large density variation with few particles as well as for the cases known to be powerful in Harlow's PIC method. Nonphysical noise, numerical thermal diffusion and viscosity were successfully reduced. A nonuniformly-spacing, moving grid system can be used for the local fine resolution of processes. (Kato, T.)

  8. The fabrication and option characteristics of polyethylene glycol-coated gold nanoparticles with different size

    International Nuclear Information System (INIS)

    Objective: To synthesize gold nanoparticles (GNPs) and polyethylene glycol-coated GNPs (PEG-GNPs)modified by sulfhydryl-polyethylene glycol (SH-PEG), chloroauric acid and different reductant agent,such as trisodium citrate and sodium borohydride were used. Methods: Chloroauric acid solution was brought to a boil,and then different volume of trisodium citrate solution or sodium borohydride solution was added to the boiling solution. Then the mixture was boiled for a further 30 minutes. Subsequently some SH-PEG was mixed with the GNPs and stirred for 1 hour to fabricate the PEG-GNPs. The optical characteristic and size of GNPs and PEG-GNPs were observed by UV-Vis spectrophotometer and transmission electron microscopic respectively. Results: 10, 25, and 45 nm GNPs were fabricated using 1% trisodium citrate,while the 5 nm GNPs were synthesized using 0.11% sodium borohydride. Meanwhile, SH-PEG was added to the GNPs and obtained the PEG-GNPs. Furthermore, when compared with the GNPs with different size,it can be found that the surface plasmon resonance (SPR) of GNPs have shift to long wavelength region with increasing particles size. The same phenomenon also can be found in the PEG-GNPs with different size. Conclusions: The size of GNPs can be modulated by controlling the ratio between chloroauric acid and trisodium citrate or sodium borohydride. Meanwhile, the larger the size of GNPs is, the more significant of the shifting to the long wavelength of SPR is. (authors)

  9. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

    2015-11-17

    Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

  10. Influence of Particle Size Distribution on Micromechanical Properties of thin Nanoparticulate Coatings

    Science.gov (United States)

    Barth, Nina; Schilde, Carsten; Kwade, Arno

    In this study the production of thin nanoparticulate coatings on solid stainless-steel substrates using dip-coating was investigated. Defined particle sizes and particle size distributions of Al2O3-nanoparticles were adjusted by stirred media milling using various operating parameters. Using nanoindentation the influence of particle size and width of the particle size distribution on the mechanical properties was investigated. In particular the establishment of nanoindentation routines for particulate thin films in contrast to hard coatings is discussed. Nanoindentation appears to be an efficient method for analysing mechanical properties of said thin coatings. It will be shown, that the influence of the substrate can be neglected for small indent depth while the coating's surface roughness influences the employed routine of the nanoindentation. The effect of the median particle size and the width of the particle size distribution on the coating structure and the micromechanical coating properties will be discussed. As a result, the maximum indentation force decreases with decreasing particle size but rises again once the nanoparticles reach very small sizes. A change in the width of the particle size distribution influences the micromechanical properties and coating structure as well.

  11. Characteristics of aerosol size distributions and chemical compositions during wintertime pollution episodes in Beijing

    Science.gov (United States)

    Liu, Zirui; Hu, Bo; Zhang, Junke; Yu, Yangchun; Wang, Yuesi

    2016-02-01

    To characterize the features of particle pollution, continuous measurements of particle number size distributions and chemical compositions were performed at an urban site in Beijing in January 2013. The particle number and volume concentration from 14 nm to 1000 nm were (37.4 ± 15.3) × 103 cm- 3 and (85.2 ± 65.6) μm3 cm- 3, respectively. N-Ait (Aitken mode) particles dominated the number concentration, whereas N-Acc (accumulation mode) particles dominated the volume concentration. Submicron particles were generally characterized by a high content of organics and SO42 -, and a low level of NO3- and Cl-. Two types of pollution episodes were observed, characterized by the "explosive growth" (EXP) and "sustained growth" (SUS) of PM2.5. Fine particles greater than 100 nm dominated the volume concentration during the ends of these pollution episodes, shifting the maximum of the number size distribution from 60 nm to greater than 100 nm in a few hours (EXP) or a few days (SUS). Secondary transformation is the main reason for the pollution episodes; SO42 -, NO3- and NH4+ (SNA) accounted for approximately 42% (EXP) and greater than 60% (SUS) of the N-Acc particle mass increase. The size distributions of particulate organics and SNA varied on timescales of hours to days, the characteristics of which changed from bimodal to unimodal during the evolution of haze episodes. The accumulation mode (peaking at approximately 500-700 nm) was dominated by organics that appeared to be internally mixed with nitrate or sulfate. The sulfate was most likely formed via heterogeneous reactions, because the SOR was constant under dry conditions (RH 50%, suggesting an important contribution from heterogeneous reactions with abundant aerosol water under wet conditions. Finally, the correlations between [NO3-]/[SO42 -] and [NH4+]/[SO42 -] suggest that the homogenous reaction between HNO3 and NH3 dominated the formation of nitrate under conditions of lower aerosol acidity. Therefore

  12. Inversion of particle size distribution by spectral extinction technique using the attractive and repulsive particle swarm optimization algorithm

    Directory of Open Access Journals (Sweden)

    Qi Hong

    2015-01-01

    Full Text Available The particle size distribution (PSD plays an important role in environmental pollution detection and human health protection, such as fog, haze and soot. In this study, the Attractive and Repulsive Particle Swarm Optimization (ARPSO algorithm and the basic PSO were applied to retrieve the PSD. The spectral extinction technique coupled with the Anomalous Diffraction Approximation (ADA and the Lambert-Beer Law were employed to investigate the retrieval of the PSD. Three commonly used monomodal PSDs, i.e. the Rosin-Rammer (R-R distribution, the normal (N-N distribution, the logarithmic normal (L-N distribution were studied in the dependent model. Then, an optimal wavelengths selection algorithm was proposed. To study the accuracy and robustness of the inverse results, some characteristic parameters were employed. The research revealed that the ARPSO showed more accurate and faster convergence rate than the basic PSO, even with random measurement error. Moreover, the investigation also demonstrated that the inverse results of four incident laser wavelengths showed more accurate and robust than those of two wavelengths. The research also found that if increasing the interval of the selected incident laser wavelengths, inverse results would show more accurate, even in the presence of random error.

  13. OPTICAL INSTRUMENT FOR IN-STACK MONITORING OF PARTICLE SIZE

    Science.gov (United States)

    A new light scattering instrument for in-situ measurements of particulates in the 0.2 to 10.0 micrometer diameter size range is described. Two modes of scattering are used, each with two wavelengths of light, to generate five size fractions by volume from a distribution of partic...

  14. Fluoroalkyl-functionalized silica particles: synthesis, characterization, and wetting characteristics.

    Science.gov (United States)

    Campos, Raymond; Guenthner, Andrew J; Haddad, Timothy S; Mabry, Joseph M

    2011-08-16

    Fluoroalkyl-functionalized silica particles for use in nonwetting surfaces were prepared by treatment of silica particles with fluoroalkyl-functional chlorosilanes. Both fumed and precipitated silica were studied, as well as the efficiency of surface coverage using mono-, di-, and trifunctional chlorosilanes. The most effective surface treatment was accomplished via the surface grafting of monofunctional chlorosilanes in the presence of preadsorbed dimethylamine under anhydrous conditions at room temperature. Confirmation of covalent attachment was accomplished via Fourier transform infrared (FT-IR) spectroscopy, while elemental analysis, thermogravimetric analysis, and nitrogen adsorption isotherms were used to determine grafting densities and additional key geometric characteristics of the grafted layer. The effect of residual silanol content on the moisture uptake properties of the modified silica particles was determined by measuring the water uptake of unbound particles, while liquid wetting properties were determined by dynamic contact angle analysis of elastomeric composites. Although residual silanol content was shown to effect wetting properties, results suggest that surface geometry dominates the performance of liquid-repellent surfaces. The potential use of fluoroalkyl-functionalized silica particles for hydrophobic and oleophobic applications is discussed. PMID:21728328

  15. Effect of Particle Size and Grinding Time on Gold Dissolution in Cyanide Solution

    Directory of Open Access Journals (Sweden)

    Jessica Egan

    2016-07-01

    Full Text Available The recovery of gold by ore leaching is influenced by the size of the particles and the chemical environment. The effect of particle size on the dissolution of gold is usually studied using mono-size particles as the gold in solution comes from the ore of a unique leached particle size. This paper proposes a method to estimate the gold dissolution as a function of particle size using a bulk ore sample, i.e., with the dissolved gold coming from the various sizes of particles carried by the ore. The results are consistent with the fact that gold dissolution increases with the decreasing particle size but results also indicate that gold dissolution of the ore within a size interval is not significantly affected by the grinding time used for the ore size reduction. Results also show a good dissolution of the gold contained in the fine-size fractions without oxidation and lead nitrate pre-treatment for an ore that is known to require such pre-treatment.

  16. Particle size distribution measurements of manganese-doped ZnS nanoparticles.

    Science.gov (United States)

    Dieckmann, Yvonne; Cölfen, Helmut; Hofmann, Heinrich; Petri-Fink, Alke

    2009-05-15

    We performed particle size and particle size distribution measurements for L-cysteine-stabilized ZnS/Mn nanoparticles in the size region below 10 nm. For this we applied transmission electron microscopy (TEM), analytical ultracentrifugation (AUC), dynamic light scattering (DLS), and asymmetric flow field flow fractionation (aF-FFF) measurements, and we calculated particle sizes with the help of X-ray diffraction (XRD) patterns and the shift of the band gap absorption in the UV-vis spectrum. The different methods are explained, and their limitations are discussed, with the conclusion that only a combination of different techniques can yield a realistic and complete picture about the size distribution of the sample. From these methods TEM, AUC, DLS, and aF-FFF measure the actual particle size distribution either in dispersion or after drying of the sample, whereas the particle size obtained from XRD patterns and with the help of the band gap widening corresponds to the average size of the crystal domains within the particles. We obtained particle size distributions with their maximum between 3 and 7 nm and a mean crystallite size of 3.5-4 nm. PMID:19374425

  17. Particle size effects in Fischer-Tropsch synthesis by Co catalyst supported on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Ali Nakhaei Pour; Elham Hosaini; Mohammad Izadyar; Mohammad Reza Housaindokht

    2015-01-01

    The effect of Co particle size on the Fischer-Tropsch synthesis (FTS) activity of carbon nanotube (CNT)-supported Co catalysts was investigated. Microemulsion (using water-to-surfactant molar ratios of 2 to12) and impregnation techniques were used to prepare catalysts with different Co particle sizes. Kinetic studies were performed to understand the effect of Co particle size on catalytic activity. Size-dependent kinetic parameters were developed using a thermodynamic method, to evaluate the structural sensitivity of the CNT-supported Co catalysts. The size-independent FTS reaction rate constant and size-independent adsorption parameter increased with increasing reac-tion temperature. The Polani parameter also depended on catalyst particle size, because of changes in the catalyst surface coverage.

  18. Seasonal Variations of Number Size Distributions and Mass Concentrations of Atmospheric Particles in Beijing

    Institute of Scientific and Technical Information of China (English)

    YU Jianhua; Benjamin GUINOT; YU Tong; WANG Xin; LIU Wenqing

    2005-01-01

    Particle number and mass concentrations were measured in Beijing during the winter and summer periods in 2003, together with some other parameters including black carbon (BC) and meteorological conditions. Particle mass concentrations exhibited low seasonality, and the ratio of PM2.5/PM10 in winter was higher than that in summer. Particle number size distribution (PSD) was characterized by four modes and exhibited low seasonality. BC was well correlated with the number and mass concentrations of accumulation and coarse particles, indicating these size particles are related to anthropogenic activities.Particle mass and number concentrations (except ultra-fine and nucleation particles) followed well the trends of BC concentration for the majority of the day, indicating that most particles were associated with primary emissions. The diurnal number distributions of accumulation and coarse mode particles were characterized by two peaks.

  19. Prediction of dryout heat flux of volumetrically heated particulate beds packed with multi-size particles

    International Nuclear Information System (INIS)

    This paper presents MEWA code calculations for the experiments performed on the POMECO-HT facility to investigate the dryout heat flux of various particulate beds, with the objective to interpret the experimental data and validate the code. The code is then applied to coolability assessment for ex-vessel debris beds related to severe accident scenarios of a boiling water reactor (BWR). The characteristics of a prototypical debris bed, such as multidimensionality and multiple particle sizes are emphasized in this study. The volumetrically heated particulate beds of the POMECO-HT experiments are packed with multi-size particles and equipped with a downcomer to investigate the bottom-fed coolability by natural circulation which demands 2D simulation. The results show that the MEWA code is capable of predicting the coolability of the bed with a downcomer (2D) as well as the top-flooding bed whose dryout heat flux can also be predicted by the Reed model (1D). Given the effective particle diameter (1 mm) and porosity (0.45) defined from a few FCI tests, the ex-vessel debris beds for a BWR chosen here are coolable with varied margins: i) compared with a top-flooding bed (spreading over the entire floor of the cavity), the cylindrical configuration with an annular-gap water supply enhances the coolability comparison , but the gain is marginal since the large diameter of the bed prevents the side coolant from flowing into the center of the bed; ii) a heap-like debris bed reduces rather than improves coolability due to its considerable height and base diameter; iii) a stratified debris bed with a fine-particle layer on the top may challenge the coolability. (author)

  20. Particle-size distribution and gas/particle partitioning of atmospheric polybrominated diphenyl ethers in urban areas of Greece

    Energy Technology Data Exchange (ETDEWEB)

    Mandalakis, Manolis; Besis, Athanasios [Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, GR-71003 Heraklion-Voutes (Greece); Stephanou, Euripides G. [Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, GR-71003 Heraklion-Voutes (Greece)], E-mail: stephanou@chemistry.uoc.gr

    2009-04-15

    Ambient concentrations, gas/particle partitioning and particle-size distribution of polybrominated diphenyl ethers (PBDEs) were investigated in two urban areas (Athens and Heraklion) of Greece. Atmospheric (gas + particle) concentrations of {sigma}PBDE varied from 21 to 30 pg m{sup -3} in the center of Athens and from 4 to 44 pg m{sup -3} in the suburbs of Heraklion. A predominance of particulate PBDEs was observed in Athens (71-76% in particles), whereas the opposite was evident in Heraklion (69-92% in gas phase). In both urban areas, PBDE particle-size distribution featured a distinct enrichment in smaller particles. A similar trend was also observed in aerosols of a background marine site. For all sampling sites, more than 46% of {sigma}PBDE was associated with particles of <0.57 {mu}m in diameter. Our results imply that particulate PBDEs may have long atmospheric residence time and they may be capable of reaching the deeper parts of the human respiratory system. - Analysis of size-segregated aerosol samples indicates a predominance of polybrominated diphenyl ethers in the small particle-size fraction.

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

    International Nuclear Information System (INIS)

    Research highlights: → Microstructure of MMC with larger particles becomes completely uniform, sooner. → When the number of cycles increased, tensile strength for both samples improved. → Up to the seventh cycle, tensile strength of MMC with larger particles was bigger. → First, the tensile elongation of MMCs was decreased, and then it was improved. - Abstract: In the present work, Al/10 vol.% SiC metal matrix composite (MMC) was manufactured by accumulative roll bonding (ARB) process. The silicon carbide particles with two various particle sizes of 40 and 2 μm were used. Effect of particle size on microstructure (by scanning electron microscopy) and mechanical properties (tensile strength and elongation) at various ARB cycles was investigated. It was found that the microstructural evolution in MMC with 40 μm particle size was more salient compared to the MMCs with 2 μm particle size. Also, the composite strip with 40 μm particle size became uniform with high bonding quality and without any porosity sooner than the strip of 2 μm particle size. Moreover, when the number of cycles was increased, the tensile strength for both samples was improved. The tensile strength of the composite strip with 40 μm particle size was more than the composite strip with 2 μm up to the seventh cycle. By increasing the number of cycles after the seventh cycle, the value of tensile strength of MMC with 40 μm particle size became saturated and then decreased, and its tensile strength became less than that of the composite with 2 μm particle size for the ninth and eleventh cycles. Up to the seventh cycle, when the number of ARB cycles was increased, the elongation of composite strips was decreased, but after the ninth cycle, the tensile elongation for both samples was improved.

  2. 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.

  3. 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.

  4. Nuclear fuel particles in the environment - characteristics, atmospheric transport and skin doses

    Energy Technology Data Exchange (ETDEWEB)

    Poellaenen, R

    2002-05-01

    In the present thesis, nuclear fuel particles are studied from the perspective of their characteristics, atmospheric transport and possible skin doses. These particles, often referred to as 'hot' particles, can be released into the environment, as has happened in past years, through human activities, incidents and accidents, such as the Chernobyl nuclear power plant accident in 1986. Nuclear fuel particles with a diameter of tens of micrometers, referred to here as large particles, may be hundreds of kilobecquerels in activity and even an individual particle may present a quantifiable health hazard. The detection of individual nuclear fuel particles in the environment, their isolation for subsequent analysis and their characterisation are complicated and require well-designed sampling and tailored analytical methods. In the present study, the need to develop particle analysis methods is highlighted. It is shown that complementary analytical techniques are necessary for proper characterisation of the particles. Methods routinely used for homogeneous samples may produce erroneous results if they are carelessly applied to radioactive particles. Large nuclear fuel particles are transported differently in the atmosphere compared with small particles or gaseous species. Thus, the trajectories of gaseous species are not necessarily appropriate for calculating the areas that may receive large particle fallout. A simplified model and a more advanced model based on the data on real weather conditions were applied in the case of the Chernobyl accident to calculate the transport of the particles of different sizes. The models were appropriate in characterising general transport properties but were not able to properly predict the transport of the particles with an aerodynamic diameter of tens of micrometers, detected at distances of hundreds of kilometres from the source, using only the current knowledge of the source term. Either the effective release height has

  5. Nuclear fuel particles in the environment - characteristics, atmospheric transport and skin doses

    International Nuclear Information System (INIS)

    In the present thesis, nuclear fuel particles are studied from the perspective of their characteristics, atmospheric transport and possible skin doses. These particles, often referred to as 'hot' particles, can be released into the environment, as has happened in past years, through human activities, incidents and accidents, such as the Chernobyl nuclear power plant accident in 1986. Nuclear fuel particles with a diameter of tens of micrometers, referred to here as large particles, may be hundreds of kilobecquerels in activity and even an individual particle may present a quantifiable health hazard. The detection of individual nuclear fuel particles in the environment, their isolation for subsequent analysis and their characterisation are complicated and require well-designed sampling and tailored analytical methods. In the present study, the need to develop particle analysis methods is highlighted. It is shown that complementary analytical techniques are necessary for proper characterisation of the particles. Methods routinely used for homogeneous samples may produce erroneous results if they are carelessly applied to radioactive particles. Large nuclear fuel particles are transported differently in the atmosphere compared with small particles or gaseous species. Thus, the trajectories of gaseous species are not necessarily appropriate for calculating the areas that may receive large particle fallout. A simplified model and a more advanced model based on the data on real weather conditions were applied in the case of the Chernobyl accident to calculate the transport of the particles of different sizes. The models were appropriate in characterising general transport properties but were not able to properly predict the transport of the particles with an aerodynamic diameter of tens of micrometers, detected at distances of hundreds of kilometres from the source, using only the current knowledge of the source term. Either the effective release height has been higher

  6. Characteristics of Fine Particles in an Urban Atmosphere—Relationships with Meteorological Parameters and Trace Gases

    Science.gov (United States)

    Zhang, Tianhao; Zhu, Zhongmin; Gong, Wei; Xiang, Hao; Fang, Ruimin

    2016-01-01

    Atmospheric fine particles (diameter < 1 μm) attract a growing global health concern and have increased in urban areas that have a strong link to nucleation, traffic emissions, and industrial emissions. To reveal the characteristics of fine particles in an industrial city of a developing country, two-year measurements of particle number size distribution (15.1 nm–661 nm), meteorological parameters, and trace gases were made in the city of Wuhan located in central China from June 2012 to May 2014. The annual average particle number concentrations in the nucleation mode (15.1 nm–30 nm), Aitken mode (30 nm–100 nm), and accumulation mode (100 nm–661 nm) reached 4923 cm−3, 12193 cm−3 and 4801 cm−3, respectively. Based on Pearson coefficients between particle number concentrations and meteorological parameters, precipitation and temperature both had significantly negative relationships with particle number concentrations, whereas atmospheric pressure was positively correlated with the particle number concentrations. The diurnal variation of number concentration in nucleation mode particles correlated closely with photochemical processes in all four seasons. At the same time, distinct growth of particles from nucleation mode to Aitken mode was only found in spring, summer, and autumn. The two peaks of Aitken mode and accumulation mode particles in morning and evening corresponded obviously to traffic exhaust emissions peaks. A phenomenon of “repeated, short-lived” nucleation events have been created to explain the durability of high particle concentrations, which was instigated by exogenous pollutants, during winter in a case analysis of Wuhan. Measurements of hourly trace gases and segmental meteorological factors were applied as proxies for complex chemical reactions and dense industrial activities. The results of this study offer reasonable estimations of particle impacts and provide references for emissions control strategies in industrial cities of

  7. Formation and characteristics of biomimetic mineralo-organic particles in natural surface water

    Science.gov (United States)

    Wu, Cheng-Yeu; Martel, Jan; Wong, Tsui-Yin; Young, David; Liu, Chien-Chun; Lin, Cheng-Wei; Young, John D.

    2016-01-01

    Recent studies have shown that nanoparticles exist in environmental water but the formation, characteristics and fate of such particles remain incompletely understood. We show here that surface water obtained from various sources (ocean, hot springs, and soil) produces mineralo-organic particles that gradually increase in size and number during incubation. Seawater produces mineralo-organic particles following several cycles of filtration and incubation, indicating that this water possesses high particle-seeding potential. Electron microscopy observations reveal round, bacteria-like mineral particles with diameters of 20 to 800 nm, which may coalesce and aggregate to form mineralized biofilm-like structures. Chemical analysis of the particles shows the presence of a wide range of chemical elements that form mixed mineral phases dominated by calcium and iron sulfates, silicon and aluminum oxides, sodium carbonate, and iron sulfide. Proteomic analysis indicates that the particles bind to proteins of bacterial, plant and animal origins. When observed under dark-field microscopy, mineral particles derived from soil-water show biomimetic morphologies, including large, round structures similar to cells undergoing division. These findings have important implications not only for the recognition of biosignatures and fossils of small microorganisms in the environment but also for the geochemical cycling of elements, ions and organic matter in surface water. PMID:27350595

  8. Formation and characteristics of biomimetic mineralo-organic particles in natural surface water

    Science.gov (United States)

    Wu, Cheng-Yeu; Martel, Jan; Wong, Tsui-Yin; Young, David; Liu, Chien-Chun; Lin, Cheng-Wei; Young, John D.

    2016-06-01

    Recent studies have shown that nanoparticles exist in environmental water but the formation, characteristics and fate of such particles remain incompletely understood. We show here that surface water obtained from various sources (ocean, hot springs, and soil) produces mineralo-organic particles that gradually increase in size and number during incubation. Seawater produces mineralo-organic particles following several cycles of filtration and incubation, indicating that this water possesses high particle-seeding potential. Electron microscopy observations reveal round, bacteria-like mineral particles with diameters of 20 to 800 nm, which may coalesce and aggregate to form mineralized biofilm-like structures. Chemical analysis of the particles shows the presence of a wide range of chemical elements that form mixed mineral phases dominated by calcium and iron sulfates, silicon and aluminum oxides, sodium carbonate, and iron sulfide. Proteomic analysis indicates that the particles bind to proteins of bacterial, plant and animal origins. When observed under dark-field microscopy, mineral particles derived from soil-water show biomimetic morphologies, including large, round structures similar to cells undergoing division. These findings have important implications not only for the recognition of biosignatures and fossils of small microorganisms in the environment but also for the geochemical cycling of elements, ions and organic matter in surface water.

  9. The influence of particle size on the rheological properties of plate-like iron particle based magnetorheological fluids

    International Nuclear Information System (INIS)

    This work is devoted to the dependence of particle size on magnetorheological properties of magnetorheological fluid (MRF) consisting of plate-like iron particles suspended in a carrier liquid with two aspects. One aspect is to study the influence of the particle size on the rheological properties of the MRF, and the other is to investigate the influence of small-sized particles on the large-sized MRF. In order to achieve this goal, firstly, two different types of MR suspensions have been constituted by a plate-like iron particle; one is small with an average particle size of 2 μm in diameter, and the other is large with an average particle size of 19 μm in diameter. In this work, these are denoted as S-MRF and L-MRF, respectively. Secondly, in order to check the influence of the small particle size of the large-sized MR fluid, three different weight fractions of bidisperse MRF samples are prepared. The structural and morphology of plate-like iron particles are described in detail. The magnetic properties of these MR fluids are carried out at room temperature using the magnetometer, followed by the investigation on the field-dependent rheological properties of these MR fluids. It is observed that in both the S-MRF and L-MRF, the yield stress and viscosity is increased by the increasing particle size, which directly shows a correlation with the fluid magnetization. It is also identified from the test of the bidisperse MRF samples that the yield and viscosity depend on the weight fraction due to the magnetostatic interaction between the two different sizes of particles. Based on the rheological properties, some figures of merit are derived for the proposed MRF samples, which are important in the design of the application device. The sedimentation experiments for MRF samples are performed to check the stability of the MRF each day. With the basic rheological properties and sedimentation experiments, it is clearly demonstrated that the bidisperse MR suspension with a

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

    International Nuclear Information System (INIS)

    The analysis by Laser Induced Breakdown Spectroscopy (LIBS) was proposed for the detection and the quantification of different elements in water even when the analyte is composed of particles in suspension. We have studied the effect of particle size on the LIBS signal during liquid analysis. In our study we used different particle sizes (from 2 μm to 90 μm) of Al2O3 in suspension in water. The results were compared to the signal obtained in the case of dissolved aluminum. In the case of particles, a linear correlation between the LIBS signal versus concentration was found but a significant decrease in the slope of the calibration curve was found when the particle size increased. Several hypotheses have been tested and only a partial ablation of the particles might explain this decrease in signal intensity. This effect probably does not occur at smaller particle size. We estimated 860 nm/pulse as ablated thickness from the top of the particle. A statistical analysis over all data obtained allowed us to calculate 100 μm as ablated water column depth. - Highlights: ► We have identified a decrease of calibration curve when particle size increases. ► Partial particle ablation has been identified as the origin of this effect. ► The ablation rate on Al2O3 particles in suspension in water has been estimated. ► We can determine the deepness of the interaction volume into the liquid.

  11. Facile route to silver submicron-sized particles and their catalytic activity towards 4-nitrophenol reduction

    International Nuclear Information System (INIS)

    Research highlights: → Submicron-sized Ag particles can be prepared by using EDTA as a reducing agent. → By varying the amount of EDTA, the size of Ag particles can be controlled. → By varying the hydrothermal reaction time, the size of Ag particles can be controlled. → In comparison with Ag nanoparticles, the submicron-sized Ag particles have a comparable catalytic activity. - Abstract: A facile, efficient, and environmentally friendly synthetic route was developed to fabricate silver submicron-sized particles by reducing silver nitrate with EDTA in aqueous solution. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) analysis revealed the formation of silver particles, with sizes ranging from 100 to 800 nm. By varying the amount of EDTA utilized in the reaction medium and/or hydrothermal reaction time, the size of prepared silver particles can be readily controlled. Compared with silver nanoparticles, the as-synthesized submicron-sized silver particles were found to show a comparable catalytic activity towards the reduction of 4-nitrophenol to 4-aminophenol in the presence of an excess amount of NaBH4.

  12. Facile route to silver submicron-sized particles and their catalytic activity towards 4-nitrophenol reduction

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Deli [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Xie Jimin, E-mail: Xiejm391@sohu.com [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Chen Min; Li Di; Zhu Jianjun; Qin Huiru [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2011-02-03

    Research highlights: > Submicron-sized Ag particles can be prepared by using EDTA as a reducing agent. > By varying the amount of EDTA, the size of Ag particles can be controlled. > By varying the hydrothermal reaction time, the size of Ag particles can be controlled. > In comparison with Ag nanoparticles, the submicron-sized Ag particles have a comparable catalytic activity. - Abstract: A facile, efficient, and environmentally friendly synthetic route was developed to fabricate silver submicron-sized particles by reducing silver nitrate with EDTA in aqueous solution. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) analysis revealed the formation of silver particles, with sizes ranging from 100 to 800 nm. By varying the amount of EDTA utilized in the reaction medium and/or hydrothermal reaction time, the size of prepared silver particles can be readily controlled. Compared with silver nanoparticles, the as-synthesized submicron-sized silver particles were found to show a comparable catalytic activity towards the reduction of 4-nitrophenol to 4-aminophenol in the presence of an excess amount of NaBH{sub 4}.

  13. Nitrogen mineralization and denitrification as influenced by crop residue particle size

    DEFF Research Database (Denmark)

    Ambus, P.; Jensen, E.S.

    1997-01-01

    Managing the crop residue particle size has the potential to affect N conservation in agricultural systems. We investigated the influence of barley (Hordeum vulgare) and pea (Pisum sativum) crop residue particle size on N mineralization and denitrification in two laboratory experiments. Experiment...

  14. Use of a magnetic fluid for particle size analysis by a sedimentation method

    OpenAIRE

    Dikansky, Yury; Zakinyan, Arthur; Bedganian, Marita

    2011-01-01

    Available at http://arxiv.org/abs/1104.0318v1 International audience A new method of particle size analysis of micrometer-sized particles is discussed. The improved method of sedimentation analysis with magnetic fluids has the potential and versatility to characterize polydisperse systems.

  15. Optical sensor technology for simultaneous measurement of particle speed and concentration of micro sized particles

    DEFF Research Database (Denmark)

    Clausen, Casper; Han, Anpan; Kristensen, Martin;

    2013-01-01

    as a hybrid between Laser Doppler Velocimetry and Laser Particle Counters. The experimental characterization of a lab-scale setup has been performed with polystyrene particles in the range from 750 nm to 20 μm, with various particle speeds. It is shown that particle concentrations can be determined...... independently from particle speeds and is a key advantage compared to normal Laser Particle Counters.......Experimental characterization of a sensor technology that can measure particle speed and concentration simultaneously in liquids and gases is presented here. The basic sensor principle is based on an optical element that shapes a light beam into well-defined fringes. The technology can be described...

  16. Characterization of energy barrier and particle size distribution of lyophilized ferrofluids by magnetic relaxation measurements

    International Nuclear Information System (INIS)

    The magnetic properties of a ferrofluid are strongly influenced by its particle size distribution. We analyzed a ferrofluid with an unknown particle size distribution as well as fractionated samples of the original material. The ferrofluid in our investigations consists of a mixture of maghemite and magnetite. We investigated these different samples using temperature-dependent magnetorelaxometry method. The evaluation of the Neel relaxation signal allows us a direct determination of the energy barrier distribution, which is one of the most important parameters of such systems of magnetic nanoparticles. The calculated particle volumes were compared with particle sizes determined by transmission electron microscopy

  17. Characterization of energy barrier and particle size distribution of lyophilized ferrofluids by magnetic relaxation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Schmidl, Frank [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany)]. E-mail: Frank.Schmidl@uni-jena.de; Weber, Peter [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Koettig, Torsten [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Buettner, Markus [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Prass, Stefan [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Becker, Christoph [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Mans, Michael [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); Heinrich, Jochen [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Roeder, Michael [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Wagner, Kerstin [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Berkov, Dimitr V. [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Goernert, Peter [Innovent Technologieentwicklung, Pruessingstrasse 27B, D-07743 Jena (Germany); Gloeckl, Gunnar [Institute of Pharmacy, Ernst-Moritz-Arndt-University, D-17487 Greifswald (Germany); Weitschies, Werner [Institute of Pharmacy, Ernst-Moritz-Arndt-University, D-17487 Greifswald (Germany); Seidel, Paul [Institut of Solid State Physics, Friedrich-Schiller-University Jena, D-07743 Jena (Germany)

    2007-04-15

    The magnetic properties of a ferrofluid are strongly influenced by its particle size distribution. We analyzed a ferrofluid with an unknown particle size distribution as well as fractionated samples of the original material. The ferrofluid in our investigations consists of a mixture of maghemite and magnetite. We investigated these different samples using temperature-dependent magnetorelaxometry method. The evaluation of the Neel relaxation signal allows us a direct determination of the energy barrier distribution, which is one of the most important parameters of such systems of magnetic nanoparticles. The calculated particle volumes were compared with particle sizes determined by transmission electron microscopy.

  18. Resolving particle size modality in bi-modal iron oxide nanoparticle suspensions

    International Nuclear Information System (INIS)

    Particle size modality in bi-modal iron oxide suspensions was resolved by exploiting complex ac-susceptibility (ACS), small angle X-ray scattering (SAXS) and photon cross-correlation spectroscopy. To explain dynamic magnetic response of bi-modal suspensions, the Debye model was expanded to a linear superposition form allowing for the contribution of both particle fractions. This modified and adopted model is able to resolve the bi-modal particle size distributions. The SAXS curves of mono- and bi-modal suspensions were fitted well using a Monte Carlo simulation scheme, allowing the detection of bi-modal particle size distributions with high precision

  19. Size-resolved fluxes of sub-100-nm particles over forests

    DEFF Research Database (Denmark)

    Pryor, Sara; Barthelmie, Rebecca Jane; Spaulding, A.M.;

    2009-01-01

    Dry deposition of atmospheric particles is critically dependent on particle size and plays a key role in dictating the mass and number distributions of atmospheric particles. However, modeling dry deposition is constrained by a lack of understanding of controlling dependencies and accurate size...... deposition model designed for broadleaf forest exhibits greater accord with the measurements than two previous analytical models, but modeled v d + underestimate observed values by at least a factor of two for all Dp between 6 and 100 nm. When size-resolved particle deposition velocities for Dp ... deposition velocities over forests that could reasonably be applied in regional and global atmospheric chemistry transport models....

  20. Effect of bead milling on chemical and physical characteristics of activated carbons pulverized to superfine sizes.

    Science.gov (United States)

    Partlan, Erin; Davis, Kathleen; Ren, Yiran; Apul, Onur Guven; Mefford, O Thompson; Karanfil, Tanju; Ladner, David A

    2016-02-01

    Superfine powdered activated carbon (S-PAC) is an adsorbent material with particle size between roughly 0.1-1 μm. This is about an order of magnitude smaller than conventional powdered activated carbon (PAC), typically 10-50 μm. S-PAC has been shown to outperform PAC for adsorption of various drinking water contaminants. However, variation in S-PAC production methods and limited material characterization in prior studies lead to questions of how S-PAC characteristics deviate from that of its parent PAC. In this study, a wet mill filled with 0.3-0.5 mm yttrium-stabilized zirconium oxide grinding beads was used to produce S-PAC from seven commercially available activated carbons of various source materials, including two coal types, coconut shell, and wood. Particle sizes were varied by changing the milling time, keeping mill power, batch volume, and recirculation rate constant. As expected, mean particle size decreased with longer milling. A lignite coal-based carbon had the smallest mean particle diameter at 169 nm, while the wood-based carbon had the largest at 440 nm. The wood and coconut-shell based carbons had the highest resistance to milling. Specific surface area and pore volume distributions were generally unchanged with increased milling time. Changes in the point of zero charge (pH(PZC)) and oxygen content of the milled carbons were found to correlate with an increasing specific external surface area. However, the isoelectric point (pH(IEP)), which measures only external surfaces, was unchanged with milling and also much lower in value than pH(PZC). It is likely that the outer surface is easily oxidized while internal surfaces remain largely unchanged, which results in a lower average pH as measured by pH(PZC). PMID:26657354

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

    International Nuclear Information System (INIS)

    The different methods allowing to determine the particle size distribution of aerosols by means of diffusion batteries are described. To that purpose, a new method for the processing of experimental data (percentages of particles trapped by the battery vs flow rate) was developed on the basis of calculation principles which are described and assessed. This method was first tested by numerical simulation from a priori particle size distributions and then verified experimentally using a fine uranine aerosol whose particle size distribution as determined by our method was compared with the distribution previously obtained by electron microscopy. The method can be applied to the determination of particle size distribution spectra of fine aerosols produced by 'radiolysis' of atmospheric gaseous impurities. Two other applications concern the detection threshold of the condensation nuclei counter and the 'critical' radii of 'radiolysis' particles

  2. Particle size effect for cobalt Fischer-Tropsch catalysts based on in situ CO chemisorption

    Science.gov (United States)

    Yang, Jia; Frøseth, Vidar; Chen, De; Holmen, Anders

    2016-06-01

    The cobalt particle size effect on activity and selectivity for CO hydrogenation was revisited on cobalt catalysts supported on a large variety of supports at 483 K, 1.85 bar, and H2/CO/Ar = 15/1.5/33.5 Nml/min. The size dependence of the activity and selectivity was analyzed in terms of site coverage and rate constants based on SSITKA experimental results. It was found that the Co particle size index estimated by the conventional method, namely, ex situ hydrogen chemisorption, could not correlate well the activity and selectivity as a function of the particle size index. The same holds for the site coverage of CO and intermediates leading to methane formation. However, the cobalt particle size index based on in situ CO chemisorption measured at 373 K provides a good correlation for turnover frequencies (TOFs) at reaction conditions. It was observed that TOF for CO conversion (TOFCO) increased with increasing particle size index of cobalt and SSITKA experiments showed that this was possibly due to increased site coverage of CO. The TOF for methane formation (TOFCH4) increased with particle size and remained constant at higher particle sizes possibly due to combined effect from the site coverage of intermediates leading to methane (θCHx) and the pseudo-first-order rate constant (kt). The results suggest that the support can play an important role for the size dependence of the activity and selectivity of CO hydrogenation on Co catalysts.

  3. Particle-size distribution and packing fraction of geometric random packings

    NARCIS (Netherlands)

    Brouwers, H.J.H.

    2006-01-01

    This paper addresses the geometric random packing and void fraction of polydisperse particles. It is demonstrated that the bimodal packing can be transformed into a continuous particle-size distribution of the power law type. It follows that a maximum packing fraction of particles is obtained when t

  4. Determination of Particle Size by Diffraction of Light

    Science.gov (United States)

    Rinard, Phillip M.

    1974-01-01

    Describes a simplified diffraction experiment offered in a workshop with the purpose of illustrating to high school students the relation of science to society. The radii determined for cigarette smoke particles range from 0.2 to 0.5 micrometer in this experiment. Included is a description of the diffraction theory. (CC)

  5. Particle size effects on bioaccessible amounts of ingestible soil-borne toxic elements.

    Science.gov (United States)

    Qin, Junhao; Nworie, Obinna Elijah; Lin, Chuxia

    2016-09-01

    The unified BARGE method was used to examine the effects of soil particle size on the bioaccessible amounts of potentially toxic elements in multi-contaminated soils from a closed landfill site. The results show that bioaccessible As, Al, Cd, Cr, Cu, Mn, Ni, Pb and Zn increased with decreasing soil particle size and the particle size effect on bioaccessibility of As and Al in the gastrointestinal phase: As bioaccessibility decreased with decreasing particle size, and the finer soil fractions tended to have a higher Al bioaccessibility, as compared to the coarser soil fractions. The research findings prompt the need for further division of soil particle size fractions in order to more accurately assess the bioaccessible amounts of soil-borne potentially toxic elements in contaminated lands. PMID:27337436

  6. Size control of rhodium particles of silica-supported catalysts using water-in-oil microemulsion

    Science.gov (United States)

    Kishida, Masahiro; Hanaoka, Toshiaki; Kim, Won Young; Nagata, Hideo; Wakabayashi, Katsuhiko

    1997-11-01

    Effects of components of water-in-oil microemulsions on rhodium particle sizes of silica-supported rhodium catalysts were investigated in the catalyst preparation method using microemulsion. In the case of the microemulsion of polyoxyethylene(23)dodecyl ether/ n-alcohols/RhCl 3 aq., the rhodium particle size increased from 3.4 to 5.0 nm as the specific permittivity of the organic solvent increased. The chain length of hydrophilic group of polyoxyethylene- p-nonylphenyl ether ( n = 5 to 15) employed as surfactants had an effect on the rhodium particle size where the rhodium size ranged between 2.0 and 3.6 nm. The rhodium particle size was 1.5 nm in the case of sodium bis(2-ethylhexyl) sulfocuccinate and this value was found to be the smallest. These results could be interpreted in terms of the adsorption of the surfactant on rhodium-hydrazine particle surface.

  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. Limitations on the use of laser velocimeter signals for particle sizing

    Science.gov (United States)

    Orloff, K. L.; Myer, F. C.; Mikasa, M. F.; Phillips, J. R.

    1976-01-01

    The paper discusses the complex relationship existing between the diameter of a particle, its index of refraction, and the output signal of a fringe-type laser velocimeter, and describes a special purpose laser velocimeter for aerosol sizing that determines aerosol size distributions on the basis of Farmer's (1973) relationship between visibility and particle size. In experiments with particles of known size, this relationship is in qualitative agreement with the experimentally observed results, the main differences being that (1) the visibility does not assume a minimum value of zero, as predicted, and (2) the visibility value above which there is no ambiguity in the corresponding fringe spacing is higher than that predicted.

  9. Particle size effects in the thermal conductivity enhancement of copper-based nanofluids

    Science.gov (United States)

    Saterlie, Michael; Sahin, Huseyin; Kavlicoglu, Barkan; Liu, Yanming; Graeve, Olivia

    2011-12-01

    We present an analysis of the dispersion characteristics and thermal conductivity performance of copper-based nanofluids. The copper nanoparticles were prepared using a chemical reduction methodology in the presence of a stabilizing surfactant, oleic acid or cetyl trimethylammonium bromide (CTAB). Nanofluids were prepared using water as the base fluid with copper nanoparticle concentrations of 0.55 and 1.0 vol.%. A dispersing agent, sodium dodecylbenzene sulfonate (SDBS), and subsequent ultrasonication was used to ensure homogenous dispersion of the copper nanopowders in water. Particle size distribution of the copper nanoparticles in the base fluid was determined by dynamic light scattering. We found that the 0.55 vol.% Cu nanofluids exhibited excellent dispersion in the presence of SDBS. In addition, a dynamic thermal conductivity setup was developed and used to measure the thermal conductivity performance of the nanofluids. The 0.55 vol.% Cu nanofluids exhibited a thermal conductivity enhancement of approximately 22%. In the case of the nanofluids prepared from the powders synthesized in the presence of CTAB, the enhancement was approximately 48% over the base fluid for the 1.0 vol.% Cu nanofluids, which is higher than the enhancement values found in the literature. These results can be directly related to the particle/agglomerate size of the copper nanoparticles in water, as determined from dynamic light scattering.

  10. Particle size effects in the thermal conductivity enhancement of copper-based nanofluids

    Directory of Open Access Journals (Sweden)

    Sahin Huseyin

    2011-01-01

    Full Text Available Abstract We present an analysis of the dispersion characteristics and thermal conductivity performance of copper-based nanofluids. The copper nanoparticles were prepared using a chemical reduction methodology in the presence of a stabilizing surfactant, oleic acid or cetyl trimethylammonium bromide (CTAB. Nanofluids were prepared using water as the base fluid with copper nanoparticle concentrations of 0.55 and 1.0 vol.%. A dispersing agent, sodium dodecylbenzene sulfonate (SDBS, and subsequent ultrasonication was used to ensure homogenous dispersion of the copper nanopowders in water. Particle size distribution of the copper nanoparticles in the base fluid was determined by dynamic light scattering. We found that the 0.55 vol.% Cu nanofluids exhibited excellent dispersion in the presence of SDBS. In addition, a dynamic thermal conductivity setup was developed and used to measure the thermal conductivity performance of the nanofluids. The 0.55 vol.% Cu nanofluids exhibited a thermal conductivity enhancement of approximately 22%. In the case of the nanofluids prepared from the powders synthesized in the presence of CTAB, the enhancement was approximately 48% over the base fluid for the 1.0 vol.% Cu nanofluids, which is higher than the enhancement values found in the literature. These results can be directly related to the particle/agglomerate size of the copper nanoparticles in water, as determined from dynamic light scattering.

  11. Design of a Particle Shadow-graph Velocimetry and Size (PSVS) System to Determine Particle Size and Density Distributions in Hanford Nuclear Tank Wastes - 12280

    International Nuclear Information System (INIS)

    Accurate particle size and density distributions for nuclear tank waste materials are essential information that helps determine the engineering requirements for a host of waste management unit operations (e.g., tank mixing, pipeline transport, and filtration). The most prevalent approach for determining particle size and density distribution is highly laborious and involves identifying individual particles using scanning electron microscope/x-ray diffraction and then acquiring the density of the materials from the technical literature. Other methods simply approximate individual particle densities by assuming chemical composition, rather than obtaining actual measurements of particle density. To overcome these limitations, a Particle Shadow-graph Velocimetry and Size (PSVS) system has been designed to simultaneously obtain particle size and density distributions for a broad range of Hanford tank waste materials existing as both individual particles and agglomerates. The PSVS system uses optical hardware, a temperature-controlled settling column, and particle introduction chamber to accurately and reproducibly obtain images of settling particles. Image analysis software provides a highly accurate determination of both particle terminal velocity and equivalent spherical particle diameter. The particle density is then calculated from Newton's terminal settling theory. The PSVS system was designed to accurately image particle/agglomerate sizes between 10 and 1000 μm and particle/agglomerate densities ranging from 1.4 to 11.5 g/cm3, where the maximum terminal velocity does not exceed 10 cm/s. Preliminary testing was completed with standard materials and results were in good agreement with terminal settling theory. Recent results of this method development are presented, as well as experimental design. The primary goal of these PSVS system tests was to obtain accurate and reproducible particle size and velocity measurements to estimate particle densities within 20

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

    International Nuclear Information System (INIS)

    One of the key questions in severe accident research is the coolability of the debris bed, i.e., whether decay heat can be completely removed by the coolant flow into the debris bed. Extensive experimental and analytical work has been done to substantiate the coolability research. Most of the available experimental data is related to the beds packed with single size (mostly spherical) particles, and less data is available for multi-size/irregular-shape particles. There are several analytical models available, which rely on the mean particle diameter and porosity of the bed in their predictions. Two different types of particles were used to investigate coolability of particulate beds at VTT, Finland. The first type is irregular-shape Aluminum Oxide gravel particles whose sizes vary from 0.25 mm to 10 mm, which were employed in the STYX experiment programme (2001-2008). The second type is spherical beads of Zirconium silicate whose sizes vary between 0.8 mm to 1 mm, which were used in the COOLOCE tests (Takasuo et al., 2012) to study the effect of multi-dimensional flooding on coolability. In the present work, the two types of particles are used in the POMECO-FL and POMECO-HT test facility to obtain their effective particle diameters and dryout heat flux of the beds, respectively. The main idea is to check how the heaters' orientations (vertical in COOLOCE vs. horizontal in POMECO-HT) and diameters (6 mm in COOLOCE vs. 3 mm in POMECO-HT) affect the coolability (dryout heat flux) of the test beds. The tests carried out on the POMECO-FL facility using a bed packed with aluminum oxide gravel particles show the effective particle diameter of the gravel particles is 0.65 mm, by which the frictional pressure gradient can be predicted by the Ergun equation. After the water superficial velocity is higher than 0.0025 m/s, the pressure gradient is underestimated. The effective particle diameter of the zirconium particles is found as 0.8 mm. The dryout heat flux is measured on

  13. Ion acoustic and dust acoustic waves at finite size of plasma particles

    International Nuclear Information System (INIS)

    We consider the influence of the finite size of ions on the properties of classic plasmas. We focus our attention at the ion acoustic waves for electron-ion plasmas. We also consider the dusty plasmas where we account the finite size of ions and particles of dust and consider the dispersion of dust acoustic waves. The finite size of particles is a classical effect as well as the Coulomb interaction. The finite size of particles considerably contributes to the properties of the dense plasmas in the small wavelength limit. Low temperature dense plasmas, revealing the quantum effects, are also affected by the finite size of plasma particles. Consequently, it is important to consider the finite size of ions in the quantum plasmas as well

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

    Science.gov (United States)

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

    2007-03-01

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

  15. Alpha spectrometry for particle size determination of mineral sands dust samples

    International Nuclear Information System (INIS)

    A method is proposed for assessing the size distribution of the radioactive particles directly from the alpha spectrum of a dust sample. The residual range distribution of alpha particles emerging from a sphere containing a monoenergetic alpha emitter is simply a quadratic function of the diameter of the sphere. The residual range distribution from a typical dust particle closely approximates that of a sphere of the same mass. For mixtures of various size particles of similar density the (multiparticle) residual range distribution can thus readily be calculated for each of the alpha emitters contained in the particles. Measurement of the composite residual range distribution can be made in a vacuum alpha spectrometer provided the dust sample has no more than a monolayer of particles. The measured energy distribution is particularly sensitive to upper particle size distributions in the diameter region of 4μm to 20μm of 5 mg/cm3 density particles, i.e. 2 to 10 mg/ch2. For dust particles containing212Po or known ratios of alpha emitters a measured alpha spectrum can be unraveled to the underlying particle size distribution. Uncertainty in the size distribution has been listed as deserving research priority in the overall radiation protection program of the mineral sands industry. The proposed method had the potential of reducing this uncertainty, thus permitting more effective radiation protection control. 2 refs., 1 tabs., 1 figs

  16. Experimental study on size-dependency of effective permittivity of particle-gas mixture with agglomeration

    Institute of Scientific and Technical Information of China (English)

    Li Xiaomin; Xu Lijun; Li Songyun

    2007-01-01

    The effective medium approximation (EMA) theory is the basis of a capacitance sensor used for concentration measurement of a particulate solid flow, its measurement result is independent on particle size. In existence of particle agglomeration or aggradation, however, it is found that the effective permittivity of a gas/solid mixture is dependent on particle size. In this paper, a parallel plate, differential capacitance sensor is utilized to investigate the influence of particle size on the effective permittivity of the mixture in such a case. Static experiments using three materials including glass, limestone and quartz particles were carried out in an off-line manner. The volume fraction of particles being tested ranged from 20×10-6 to 600×10-6, while the particle size was between 3 and 100 μm. Experimental results show that the effective permittivity of a particle-gas mixture with particle agglomeration is larger than that predicted by EMA and the smaller the particle size, the larger the effective permittivity. The experiment process and analysis results are discussed in detail in the paper.

  17. Characteristics of wave-particle interaction in a hydrogen plasma

    International Nuclear Information System (INIS)

    We study the characteristics of cyclotron wave-particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy Emin, resonant wave frequency ω, and pitch angle diffusion coefficient Dαα for interactions between R-mode/L-mode and electrons/protons are presented. It is found that Emin decreases with ω for R-mode/electron, L-mode/proton and L-mode/electron interactions, but increase with ω for R-mode/proton interaction. It is shown that both R-mode and L-mode waves can efficiently scatter energetic (10 keV-100 keV) electrons and protons and cause precipitation loss at L=4, indicating that perhaps wave-particle interaction is a serious candidate for the ring current decay. (authors)

  18. 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

  19. Effect of sodium citrate on preparation of nano-sized cobalt particles by organic colloidal process

    Institute of Scientific and Technical Information of China (English)

    Huaping ZHU; Hao LI; Huiyu SONG; Shijun LIAO

    2009-01-01

    Nano-sized cobalt particles with the diameter of 2 nm were prepared via an organic colloidal process with sodium formate, ethylene glycol and sodium citrate as the reducing agent, the solvent and the complexing agent, respectively. The effects of sodium citrate on the yield, crystal structure, particle size and size distribution of the prepared nano-sized cobalt particles were then investigated. The results show that the average particle diameter decreases from 200 nm to 2 nm when the molar ratio of sodium citrate to cobalt chloride changes from 0 to 6. Furthermore, sodium citrate plays a crucial role in the controlling of size distribution of the nano-sized particles. The size distribution of the particle without sodium citrate addition is in range from tens of nanometers to 300 or 400 nm, while that with sodium citrate addition is limited in the range of (2±0.25) nm. Moreover, it is found that the addition of sodium citrate as a complex agent could decrease the yield of the nano-sized cobalt particle.

  20. The Influence of the Particle Size on the Adhesion Between Ceramic Particles and Metal Matrix in MMC Composites

    Science.gov (United States)

    Jarzabek, Dariusz M.; Chmielewski, Marcin; Dulnik, Judyta; Strojny-Nedza, Agata

    2016-05-01

    This study investigated the influence of the particle size on the adhesion force between ceramic particles and metal matrix in ceramic-reinforced metal matrix composites. The Cu-Al2O3 composites with 5 vol.% of ceramic phase were prepared by a powder metallurgy process. Alumina oxide powder as an electrocorundum (Al2O3) powder with different particle sizes, i.e., fine powder materials and carried out the experiments with the use of the self-made tensile tester. We have observed that the interface strength is higher for the sample with coarse particles and is equal to 74 ± 4 MPa and it is equal to 68 ± 3 MPa for the sample with fine ceramic particles.

  1. Lifetimes and Sizes from Two-Particle Correlation Functions

    OpenAIRE

    Heinz, U.; Tomasik, B.; Wiedemann, U. A.; Wu, Y. -F.

    1996-01-01

    We discuss the Yano-Koonin-Podgoretskii (YKP) parametrization of the two-particle correlation function for azimuthally symmetric expanding sources. We derive model-independent expressions for the YKP fit parameters and discuss their physical interpretation. We use them to evaluate the YKP fit parameters and their momentum dependence for a simple model for the emission function and propose new strategies for extracting the source lifetime. Longitudinal expansion of the source can be seen direc...

  2. Estimation of size distribution of primary particles after evaporation or urane(IV) oxide

    International Nuclear Information System (INIS)

    Studying the behaviour of urane oxide aerossoles in a closed system the size distribution of the particles resulting from evaporation of UO2 was also investigated. They were precipitated on formfar coated specimen supports grids and photographed with an electron microscope. For the estimation of the size distribution the projected diameter was used. The results show that the size distribution of the primary particles corresponds to a logarithmic normal distribution. (author)

  3. Characteristics of defective phage particles of Pectobacterium carotovorum ZM1.

    Science.gov (United States)

    Tovkach, F I; Ivanytsia, T V; Kushkina, A I

    2012-01-01

    It is shown for the first time that the expression products of defective prophages are typical of defective lysogenic systems of phytopathogenic Pectobacterium carotovorum. It is established that virus-like particles (LP) such as phage capsids are packing bacterial DNA which size is determined by pulse field gel electrophoresis separation. Based on data about capsid structures which are formed by the virulent mutant ZF40/421, there is made a suggestion about the forming mechanism of defective virions of P carotovorum. PMID:22545442

  4. Particle size-dependent leakage and losses of aerosols in respirators

    Energy Technology Data Exchange (ETDEWEB)

    Holton, P.M.; Tackett, D.L.; Willeke, K.

    1987-10-01

    Measuring particle size-dependent leakage into and losses inside a respirator reveals the deposition mechanisms occurring at the leak site and the flow dynamics inside the respirator. This study investigated particle size-dependent leakage and deposition within the mask by examining the leakage into the mask for different hole locations, probe locations, hole shapes, hole lengths and hole sizes. The shape of the leak has an effect on particle size-dependent leakage. Probe and leak location tests indicated that not only does the total measured leakage change but also the size-dependence of the leakage changes depending on the leak and probe locations. When the leak site is in the chin area, the clean air entering through the filters at the chin helps to carry the inward leakage into the breathing zone. Particle size-dependent leakage does occur and is due to both inertial entry losses at the leak site and within the mask, and diffusional losses within the mask and leak site. Particle size-dependent curves change shape as the hole size changes with relatively more larger particles entering through the small hole size.

  5. Effect of feed processing on size of (washed) faeces particles from pigs measured by image analysis

    DEFF Research Database (Denmark)

    Nørgaard, Peder; Kornfelt, Louise Foged; Hansen, Christian Fink;

    2005-01-01

    Our aim was to study the effect of dietary physical characteristics on size of washed faecal particles from finishing pigs (98±6 kg). The pigs were fed either a finely ground pelleted diet (FP) or a coarsely ground meal diet (CM) comparable in all ingredients. The diets were based on barley, wheat...... and soybean meal as the main ingredients and were either ground through a 2 mm screen before pelleting or ground to pass a 4.5 mm screen. Faecal samples were collected from 7 FP and 8 CM fed pigs and washed in nylon bags before drying and sieving into 3 fractions: >1 mm, 0.5-1 mm and bottom bowl...

  6. Size Distribution of Particles Emitted from Liquefied Natural Gas Fueled Engine

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The results of measurements conducted to determine the number and mass concentration of particles emitted from the liquefied natural gas (LNG) fueled spark ignition engines are presented. Particle size distributions were measured at different speeds, different loads and ESC cycles. The nanoparticles with diameter smaller than 39nm, measured by the electrical low-pressure impactor (ELPI), are dominant in number concentration that is nearly 92.7% of the total number of the emitted particles at the peak point. As for the mass of emission particle, it is shown that the mass of the particles greater than 1.2μm is more than 65% that of the emitted particles.

  7. 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.

  8. A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

    Science.gov (United States)

    Bastian, S.; Löschau, G.; Wiedensohler, A.

    2014-04-01

    An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The function control allows unattended quality assurance experiments at remote air quality monitoring or research stations under field conditions. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter while removing diffusive particles smaller than 20 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. Another feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. The performance of the function control is illustrated with the aid of a 1-year data set recorded at Annaberg-Buchholz, a station in the Saxon air quality monitoring network. During the period of concern, the total particle number concentration derived from the mobility particle size spectrometer slightly overestimated the particle number concentration recorded by the condensation particle counter by 2 % (grand average). Based on our first year of experience with the function control, we developed tolerance criteria that allow a performance evaluation of a tested mobility particle size spectrometer with respect to the total particle number concentration. We conclude that the automated function control enhances the quality and reliability of unattended long-term particle number size distribution measurements. This will have beneficial effects for intercomparison studies involving different measurement sites, and help provide a higher

  9. Theoretical Study on the Effects of Particle Size Distribution on the Optical Properties of Colloidal Gold

    International Nuclear Information System (INIS)

    Mie theory has been used to calculate the extinction of a gold nanoparticle in water by varying its diameter from 1 to 1000 nm. Utilizing this size-dependent theoretical spectrum, we have calculated the extinction spectrum of a colloidal gold by taking into account the size distribution of particle. Such calculation is in better agreement with experiment than the calculation without considering the size distribution. A least-squares fitting is used to deduce the size distribution from an experimental extinction spectrum. For particles with their diameters ranging from 10 to 28 nanometers, the fitting gives reasonable agreement with the size distribution obtained from tunneling electron microscope images

  10. Particle Size Dependence of TiO2 Electrodes in Rechargeable Lithium Battery

    Directory of Open Access Journals (Sweden)

    S. Y. Huang

    1996-01-01

    Full Text Available Particle size effects in five anatase TiO2 pellet electrodes with different particle sizes (4 ∼ 300nm and surface areas (8 ∼ 380m2/g were studied by XRD analysis, chronopotentiometry and chronoamperometry in Li/LiN(CF3SO22 + EC:DME/TiO2 cells. Nanosized TiO2 electrodes showed by 22% larger storage capacity, 50% lower overvoltage loss at the same current density, and 75% higher charge density for a given time than microsized ones; electric storage capacity enhances more rapidly with decreasing particle size and increasing surface area in a nanoscale region than in a microscale region. The particle size dependence may be explained by surface morphology of electrodes and existence of structural defects or distortion in the surface layer of TiO2 nanosized particles.

  11. Radial particle-size segregation during packing of particulates into cylindrical containers

    Science.gov (United States)

    Ripple, C.D.; James, R.V.; Rubin, J.

    1973-01-01

    In a series of experiments, soil materials were placed in long cylindrical containers, using various packing procedures. Soil columns produced by deposition and simultaneous vibratory compaction were dense and axially uniform, but showed significant radial segregation of particle sizes. Similar results were obtained with deposition and simultaneous impact-type compaction when the impacts resulted in significant container "bouncing". The latter procedure, modified to minimize "bouncing" produced dense, uniform soil columns, showing little radial particle-size segregation. Other procedures tested (deposition alone and deposition followed by compaction) did not result in radial segregation, but produced columns showing either relatively low or axially nonuniform densities. Current data suggest that radial particle-size segregation is mainly due to vibration-induced particle circulation in which particles of various sizes have different circulation rates and paths. ?? 1973.

  12. Effects of particle size on residual stresses of metal matrix composites

    Institute of Scientific and Technical Information of China (English)

    YAN Yi-wu; GENG Lin; LI Ai-bin

    2006-01-01

    A finite element analysis was carried out on the development of residual stresses during the cooling process from the fabrication temperature in the SiCp reinforced Al matrix composites. In the simulation, the two-dimensional and random distribution multi-particle unit cell model and plane strain conditions were used. By incorporating the Taylor-based nonlocal plasticity theory, the effect of particle size on the nature, magnitude and distribution of residual stresses of the composites was studied. The magnitude thermal-stress-induced plastic deformation during cooling was also calculated. The results show similarities in the patterns of thermal residual stress and strain distributions for all ranges of particle size. However, they show differences in magnitude of thermal residual stress as a result of strain gradient effect. The average thermal residual stress increases with decreasing particle size, and the residual plastic strain decreases with decreasing particle size.

  13. Size Effects in Heterogeneous Systems with Nanoscale Particles

    Czech Academy of Sciences Publication Activity Database

    Levdansky, V.V.; Smolík, Jiří; Ždímal, Vladimír

    -: -, 2011, s. pc3 16. ISBN N. [E- MRS 2011 Spring Meeting IUMRS ICAM 2011 & E- MRS / MRS Bilateral Conference on Energy. Nice (FR), 09.05.2011-13.05.2011] R&D Projects: GA ČR GA101/09/1633; GA AV ČR(CZ) IAA400720804; GA AV ČR IAA200760905 Institutional research plan: CEZ:AV0Z40720504 Keywords : nanoscale particles * aeerosol systems * gas Subject RIV: CF - Physical ; Theoretical Chemistry http://www.emrs-strasbourg.com/index.php?option=com_abstract&task=view&id=118&day=2011-05-12&year=2011&Itemid=99999999&id_season=4.

  14. Effect of sulfate and carbonate minerals on particle-size distributions in arid soils

    Science.gov (United States)

    Goossens, Dirk; Buck, Brenda J.; Teng, Yuazxin; Robins, Colin; Goldstein, Harland L.

    2014-01-01

    Arid soils pose unique problems during measurement and interpretation of particle-size distributions (PSDs) because they often contain high concentrations of water-soluble salts. This study investigates the effects of sulfate and carbonate minerals on grain-size analysis by comparing analyses in water, in which the minerals dissolve, and isopropanol (IPA), in which they do not. The presence of gypsum, in particular, substantially affects particle-size analysis once the concentration of gypsum in the sample exceeds the mineral’s solubility threshold. For smaller concentrations particle-size results are unaffected. This is because at concentrations above the solubility threshold fine particles cement together or bind to coarser particles or aggregates already present in the sample, or soluble mineral coatings enlarge grains. Formation of discrete crystallites exacerbates the problem. When soluble minerals are dissolved the original, insoluble grains will become partly or entirely liberated. Thus, removing soluble minerals will result in an increase in measured fine particles. Distortion of particle-size analysis is larger for sulfate minerals than for carbonate minerals because of the much higher solubility in water of the former. When possible, arid soils should be analyzed using a liquid in which the mineral grains do not dissolve, such as IPA, because the results will more accurately reflect the PSD under most arid soil field conditions. This is especially important when interpreting soil and environmental processes affected by particle size.

  15. Particle-size distribution of polybrominated diphenyl ethers (PBDEs) and its implications for health

    Science.gov (United States)

    Lyu, Y.; Xu, T.; Li, X.; Cheng, T.; Yang, X.; Sun, X.; Chen, J.

    2015-12-01

    In order better to understand the particle-size distribution of particulate PBDEs and their deposition pattern in human respiratory tract, we made an one year campaign 2012-2013 for the measurement of size-resolved aerosol particles at Shanghai urban site. The results showed that particulate PBDEs exhibited a bimodal distribution with a mode peak in the accumulation particle size range and the second mode peak in the coarse particle size ranges. As the number of bromine atoms in the molecule increased, accumulation mode peak intensity increased while coarse mode peak intensity decreased. This change was the consistent with the variation of PBDEs' sub-cooled vapor pressure. Absorption and adsorption process dominated the distribution of PBDEs among the different size particles. Evaluated deposition flux of Σ13PBDE was 26.8 pg h-1, in which coarse particles contributed most PBDEs in head and tracheobronchial regions, while fine mode particles contributed major PBDEs in the alveoli region. In associated with the fact that fine particles can penetrate deeper into the respiratory system, fine particle-bound highly brominated PBDEs can be inhaled more deeply into human lungs and cause a greater risk to human health.

  16. Size distribution of particle-associated polybrominated diphenyl ethers (PBDEs) and their implications for health

    Science.gov (United States)

    Lyu, Yan; Xu, Tingting; Li, Xiang; Cheng, Tiantao; Yang, Xin; Sun, Xiaomin; Chen, Jianmin

    2016-03-01

    In order to better understand the size distribution of particle-associated PBDEs and their deposition pattern in the human respiratory tract, we carried out a 1-year campaign during 2012-2013 for the measurement of size-resolved particles at the urban site of Shanghai. The results showed that particulate PBDEs exhibited a bimodal distribution with a mode peak in the accumulation particle size range and the second mode peak in the coarse particle size ranges. As the number of bromine atoms in the molecule increases, accumulation-mode peak intensity increased while coarse-mode peak intensity decreased. This change was consistent with the variation of PBDEs' subcooled vapor pressure. Absorption and adsorption processes dominated the distribution of PBDEs among the different size particles. The evaluated deposition flux of Σ13 PBDEs was 26.8 pg h-1, in which coarse particles contributed most PBDEs in head and tracheobronchial regions, while fine-mode particles contributed major PBDEs in the alveoli region. In association with the fact that fine particles can penetrate deeper into the respiratory system, fine-particle-bound highly brominated PBDEs can be inhaled more deeply into human lungs and cause a greater risk to human health.

  17. Particle size and support effects in NO adsorption on model Pt and Rh catalysts

    International Nuclear Information System (INIS)

    The adsorption of NO on Rh particles supported on ZrO2 (100) and α-Al2O3(0001) and on Pt particles supported on CeO2, α-Al2O3(0001), and the Zn- and O-polar surfaces of ZnO(0001) has been studied using temperature programmed desorption (TPD). For Rh, the support affected the stability of the metal films and the final particle size but made no observable changes in NO adsorption properties. However, the TPD curves were found to be strongly dependent on the particle size for Rh. A low-temperature N2 feature which is observed on bulk metals and large particles was not seen with small Rh particles. For Pt, both support composition and particle size influenced the TPD results. The results for CeO2 and α-Al2O3(0001) were essentially identical, and the changes in the NO TPD curves appear to be due to particle size only. The implications of these results on particle size and support effects in NO reduction catalysis will be discussed

  18. Combustion characteristics of particles of hazardous solid waste mixtures in a fixed bed

    International Nuclear Information System (INIS)

    Hazardous waste disposal is vitally important as industrial production increases. Grate furnaces are a common means to incinerate hazardous waste. In this present work, a fixed bed assembly is used to experimentally model combustion within grate furnaces. Combustion characteristics are examined and the effects of primary air rate, moisture, bed height and particle size on burning rate, ignition-front speed and temperatures in the bed are also investigated. The results indicate that a rising temperature front descends through the bed while weight loss remains constant during the main combustion stage. Primary air rates and moisture content are shown to have significant effects on burning rates and average ignition-front speeds. Bed height has no effect on burning rates but does have an effect on average ignition-front speeds. Particle size is found to have slight effects on burning rates while having no effect on average ignition-front speeds.

  19. Particle size of unattached radon progeny in filtered room air

    International Nuclear Information System (INIS)

    The size distribution of the unattached radon progeny in filtered room air was measured with a serial array of wire screens. Nearly all the size distributions of 2 to 3 min air, measured with the graded wire screen samplers were unimodal, with a geometric standard deviation averaging 1.8 ± 0.058. The grand average of the geometric mean and standard error of the mean diffusion coefficient was 0.048 ± 0.0004. The results obtained using different combinations of the graded wire screens were consistent. The measured diffusion coefficient predicts a nasal penetration of 9% to 16% for inspiratory flow rates of 3 1.min-1 to 30 min-1, respectively. The results indicate that about 15% of the inhaled unattached radon progeny penetrate beyond the nose into the tracheobronchial region to deliver a radiation dose to the bronchial epithelium. (author)

  20. A novel method for size uniform 200nm particles: multimetallic particles and in vitro gene delivery

    Science.gov (United States)

    Mair, Lamar; Ford, Kris; Superfine, Richard

    2008-10-01

    We report on the fabrication of arrays of mono- and multimetallic particles via metal evaporation onto lithographically patterned posts. Metal particles evaporated on cylindrical structures 0.20μm in diameter and 0.33μm tall are released via photoresist dissolution, resulting in freely suspended, shape defined particles. These Post-Particles have highly tunable composition, as demonstrated by our deposition of five different multimetallic particle blends. We calculate the susceptibility and magnetization of 200nm Fe particles in an applied 0.081T magnetic field. In order to evaluate their usefulness as magnetofection agents an antisense oligonucleotide designed to correct the aberrant splicing of enhanced green fluorescent protein mRNA was successfully attached to Fe Post-Particles via a polyethyleneimine linker and transfected into a modified HeLa cell line.

  1. Size Dependence of Chemical Reactions in Nanoscale Aerosol Particles

    Czech Academy of Sciences Publication Activity Database

    Levdansky, V.V.; Smolík, Jiří; Moravec, Pavel

    Helsinki : -, 2010, P2L1. ISBN N. [International Aerosol Conference IAC 2010. Helsinki (FI), 29.08.2010-03.09.2010] R&D Projects: GA ČR GA104/07/1093; GA ČR GA101/09/1633; GA AV ČR(CZ) IAA400720804 Institutional research plan: CEZ:AV0Z40720504 Keywords : size effect * nanoparticles * chemical reactions Subject RIV: CF - Physical ; Theoretical Chemistry www.iac2010.fi

  2. 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

  3. Aerosol and NOx emission factors and submicron particle number size distributions in two road tunnels with different traffic regimes

    Directory of Open Access Journals (Sweden)

    D. Imhof

    2006-01-01

    Full Text Available Measurements of aerosol particle number size distributions (18–700 nm, mass concentrations (PM2.5 and PM10 and NOx were performed in the Plabutsch tunnel, Austria, and in the Kingsway tunnel, United Kingdom. These two tunnels show different characteristics regarding the roadway gradient, the composition of the vehicle fleet and the traffic frequency. The submicron particle size distributions contained a soot mode in the diameter range D=80–100 nm and a nucleation mode in the range of D=20–40 nm. In the Kingsway tunnel with a significantly lower particle number and volume concentration level than in the Plabutsch tunnel, a clear diurnal variation of nucleation and soot mode particles correlated to the traffic density was observed. In the Plabutsch tunnel, soot mode particles also revealed a diurnal variation, whereas no substantial variation was found for the nucleation mode particles. During the night a higher number concentration of nucleation mode particles were measured than soot mode particles and vice versa during the day. In this tunnel with very high soot emissions during daytime due to the heavy-duty vehicle (HDV share of 18% and another 40% of diesel driven light-duty vehicles (LDV semivolatile species condense on the pre-existing soot surface area rather than forming new particles by homogeneous nucleation. With the low concentration of soot mode particles in the Kingsway tunnel, also the nucleation mode particles exhibit a diurnal variation. From the measured parameters real-world traffic emission factors were estimated for the whole vehicle fleet as well as differentiated into the two categories LDV and HDV. In the particle size range D=18–700 nm, each vehicle of the mixed fleet emits (1.50±0.08×1014 particles km-1 (Plabutsch and (1.26±0.10×1014 particles km-1 (Kingsway, while particle volume emission factors of 0.209±0.008 cm3 km-1 and 0.036±0.004 cm3 km-1, respectively, were obtained. PM1 emission factors of 104±4 mg

  4. Particle size dependence of hit probability for lung cells

    International Nuclear Information System (INIS)

    The macroscopic quantity 'absorbed dose' loses its validity to interpret the radiation-induced biological effects in the lung inhaled with particulate α-emitters like transuranic elements, because the doses to individual cells differ more widely than the range of doses over which the dose-response relationship can be regarded as linear. We intend to make up a three-dimensional model of parenchymal lung using a stack of actual histological sections in order to computer microscopic dose distribution around particulate α-emitters. This theoretical dosimetric approach will provide a scientific basis to the extrapolation of results of animal experiments utilizing high doses to man exposed to low level radioactivity and also to the understanding of biological effects associated with high LET radiations. Lung cells which survive α-particle hits were calculated, which will be a significant index of potential risk. Three models were assumed for the structure of parenchymal lung, which were 1) structureless lung of uniform density, 2) lattice of honeycomb pattern and 3) digital image of actual histological section of rat lung. The result shows that the survival cells decrease exponentially with the diameter of inhaled particles in any models. But the slope of the curve for the structureless lung is much greater than those for any other two models. This result suggests the validity of the dosimetric approach using actual histological section to estimate the inhalation risk of particulate α-emitters. (author)

  5. The impact of fuel particle size distribution on neutron transport in stochastic media

    International Nuclear Information System (INIS)

    This paper presents a study of the particle size distribution impact on neutron transport in three-dimensional stochastic media. An eigenvalue problem is simulated in a cylindrical container consisting of fissile fuel particles with five different size distributions: constant, uniform, power, exponential and Gaussian. We construct 15 cases by altering the fissile particle volume packing fraction and its optical thickness, but keeping the mean chord length of the spherical fuel particle the same at different size distributions. The tallied effective multiplication factor (keff) and flux distribution along axial and radial directions are compared between different size distributions. At low packing fraction and low optical thickness, the size distribution has a significant impact on radiation transport in stochastic media, which can cause as high as ∼270 pcm difference in keff value and ∼2.6% relative error difference in peak flux. As the packing fraction and optical thickness increase, the impact gradually dissipates. (authors)

  6. NUMBER CONCENTRATION, SIZE DISTRIBUTION AND FINE PARTICLE FRACTION OF TROPOSPHERIC AND STRATOSPHERIC AEROSOLS

    Institute of Scientific and Technical Information of China (English)

    Li Xu; Guangyu Shi; Li Zhang; Jun Zhou; Yasunobu Iwasaka

    2003-01-01

    Aerosol observations were carried out at Xianghe Scientific Balloon Base (39.45°N, 117°E) using a stratospheric balloon. The particle number concentrations of the tropospheric and stratospheric aerosols were directly explored.The vertical distributions of the number concentration, number-size (that is, particle number versus particle size)distribution, and the fraction of fine particles (0.5 μm>r>0.15 μm/r>0.15 μm) are reported in this paper. The profiles of particle concentration present multi-peak phenomenon. The pattern of size distribution for atmospheric aerosol indicates a tri-modal (r=~0.2 μm, ~0.88 μm and ~7.0 μm) and a bi-modal (r=~0.13 μm and 2.0 μm). The number-size distribution almost fits the Junge distribution for particles with r<0.5 μm in the stratosphere of 1993 and the troposphere of 1994. But the distributions of coarse particles (r>0.5 μm) are not uniform. The number-size distribution exhibits also a wide size range in the troposphere of 1993. The results demonstrate that fine particles represent the major portion in the troposphere during the measurement period, reaching as high as 95% in 1994. Certain coarse particle peaks in the troposphere were attributed to clouds and other causes, and in the stratosphere to volcanic eruption. The stratospheric aerosol layer consists of unique fractions of fine or coarse particles depending on their sources. In summary, the process of gas-to-particles conversion was active and the coarse particles were rich over the Xianghe area. The measurements also demonstrate that the spatial and temporal atmospheric aerosol distributions are nonuniform and changeful.

  7. Ti particle-reinforced surface layers in Al: Effect of particle size on microstructure, hardness and wear

    Energy Technology Data Exchange (ETDEWEB)

    Mordyuk, B.N., E-mail: mordyuk@imp.kiev.ua [Kurdyumov Institute for Metal Physics, 36 Academician Vernadsky Boulevard, UA-03680, Kyiv (Ukraine); Silberschmidt, V.V. [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, LE11 3TU (United Kingdom); Prokopenko, G.I. [Kurdyumov Institute for Metal Physics, 36 Academician Vernadsky Boulevard, UA-03680, Kyiv (Ukraine); Nesterenko, Yu.V. [National Technical University ' Kyiv Polytechnic Institute' , 37 Peremohy Avenue, UA-03056, Kyiv (Ukraine); Iefimov, M.O. [Frantzevich Institute for Problems of Materials Science, 3 Krzhyzhanivsky Street, UA-03142, Kyiv (Ukraine)

    2010-11-15

    Two types of Ti particles are used in an ultrasonic impact peening (UIP) process to modify sub-surface layers of cp aluminium atomized, with an average size of approx. 20 {mu}m and milled (0.3-0.5 {mu}m). They are introduced into a zone of severe plastic deformation induced by UIP. The effect of Ti particles of different sizes on microstructure, phase composition, microhardness and wear resistance of sub-surface composite layers in aluminium is studied in this paper. The formed layers of a composite reinforced with smaller particles have a highly misoriented fine-grain microstructure of its matrix with a mean grain size of 200-400 nm, while reinforcement with larger particles results in relatively large Al grains (1-2 {mu}m). XRD, SEM, EDX and TEM studies confirm significantly higher particle/matrix bonding in the former case due to formation of a Ti{sub 3}Al interlayer around Ti particles with rough surface caused by milling. Different microstructures determine hardness and wear resistance of reinforced aluminium layers: while higher magnitudes of microhardness are observed for both composites (when compared with those of annealed and UIP-treated aluminium), the wear resistance is improved only in the case of reinforcement with small particles.

  8. Ti particle-reinforced surface layers in Al: Effect of particle size on microstructure, hardness and wear

    International Nuclear Information System (INIS)

    Two types of Ti particles are used in an ultrasonic impact peening (UIP) process to modify sub-surface layers of cp aluminium atomized, with an average size of approx. 20 μm and milled (0.3-0.5 μm). They are introduced into a zone of severe plastic deformation induced by UIP. The effect of Ti particles of different sizes on microstructure, phase composition, microhardness and wear resistance of sub-surface composite layers in aluminium is studied in this paper. The formed layers of a composite reinforced with smaller particles have a highly misoriented fine-grain microstructure of its matrix with a mean grain size of 200-400 nm, while reinforcement with larger particles results in relatively large Al grains (1-2 μm). XRD, SEM, EDX and TEM studies confirm significantly higher particle/matrix bonding in the former case due to formation of a Ti3Al interlayer around Ti particles with rough surface caused by milling. Different microstructures determine hardness and wear resistance of reinforced aluminium layers: while higher magnitudes of microhardness are observed for both composites (when compared with those of annealed and UIP-treated aluminium), the wear resistance is improved only in the case of reinforcement with small particles.

  9. Characteristic Studies of Micron Zinc Particle Hydrolysis in a Fixed Bed Reactor

    Directory of Open Access Journals (Sweden)

    Lv Ming

    2015-09-01

    Full Text Available Zinc fuel is considered as a kind of promising energy sources for marine propeller. As one of the key steps for zinc marine energy power system, zinc hydrolysis process had been studied experimentally in a fixed bed reactor. In this study, we focus on the characteristics of micron zinc particle hydrolysis. The experimental results suggested that the steam inner diffusion is the controlling step of accumulative zinc particles hydrolysis reaction at a relative lower temperature and a relative higher water partial pressure. In other conditions, the chemical reaction kinetics was the controlling step. And two kinds of chemical reaction kinetics appeared in experiments: the surface reaction and the gas-gas reaction. The latter one occurs usually for larger zinc particles and high reaction temperature. Temperature seems to be one of the most important parameters for the dividing of different reaction mechanisms. Several parameters of the hydrolysis process including heating rate, water partial pressure, the particle size and temperature were also studied in this paper. Results show that the initial reaction temperature of zinc hydrolysis in fixed bed is about 410°C. And the initial reaction temperature increases as the heating rate increases and as the water partial pressure decreases. The total hydrogen yield increases as the heating rate decreases, as the water partial pressure increases, as the zinc particle size decreases, and as the reaction temperature increases. A hydrogen yield of more than 81.5% was obtained in the fixed bed experiments.

  10. The effect of particle size on fracture properties and size effect of concrete

    NARCIS (Netherlands)

    Schlangen, E.; Lim, H.S.; Weerheijm, J.

    2005-01-01

    In the study the effect of scaling the material structure on the fracture behaviour of concrete is investigated. Next to this the size effect of concrete fracture strength and fracture energy is studied. The fracture mechanism of concrete made with different size aggregates are tested numerically. A

  11. The effect of particle size on hydrolysis reaction rates and rheological properties in cellulosic slurries.

    Science.gov (United States)

    Dasari, Rajesh K; Eric Berson, R

    2007-04-01

    The effect of varying initial particle sizes on enzymatic hydrolysis rates and rheological properties of sawdust slurries is investigated. Slurries with four particle size ranges (33 microm units per gram of cellulose at 50 degrees C and 250 rpm in shaker flasks. At lower initial particle sizes, higher enzymatic reaction rates and conversions of cellulose to glucose were observed. After 72 h 50 and 55% more glucose was produced from the smallest size particles than the largest size ones, for initial solids concentration of 10 and 13% (w/w), respectively. The effect of initial particle size on viscosity over a range of shear was also investigated. For equivalent initial solids concentration, smaller particle sizes result in lower viscosities such that at a concentration of 10% (w/w), the viscosity decreased from 3000 cP for 150 microm conversion of biomass to ethanol. Furthermore, the corresponding reduction in viscosity may allow for higher solids loading and reduced reactor sizes during large-scale processing. PMID:18478396

  12. Size distribution of aerosol particles produced during mining and processing uranium ore.

    Science.gov (United States)

    Mala, Helena; Tomasek, Ladislav; Rulik, Petr; Beckova, Vera; Hulka, Jiri

    2016-06-01

    The aerosol particle size distributions of uranium and its daughter products were studied and determined in the area of the Rožná mine, which is the last active uranium mine in the Czech Republic. A total of 13 samples were collected using cascade impactors from three sites that had the highest expected levels of dust, namely, the forefield, the end of the ore chute and an area close to workers at the crushing plant. The characteristics of most size distributions were very similar; they were moderately bimodal, with a boundary approximately 0.5 μm between the modes. The activity median aerodynamic diameter (AMAD) and geometric standard deviation (GSD) were obtained from the distributions beyond 0.39 μm, whereas the sizes of particles below 0.39 μm were not differentiated. Most AMAD and GSD values in the samples ranged between 3.5 and 10.5 μm and between 2.8 and 5.0, respectively. The geometric means of the AMADs and GSDs from all of the underground sampling sites were 4.2 μm and 4.4, respectively, and the geometric means of the AMADs and GSDs for the crushing plant samplings were 9.8 μm and 3.3, respectively. The weighted arithmetic mean of the AMADs was 4.9 μm, with a standard error of 0.7 μm, according to the numbers of workers at the workplaces. The activity proportion of the radon progeny to (226)Ra in the aerosol was 0.61. PMID:27032340

  13. Wind tunnel study of twelve dust samples by large particle size

    Science.gov (United States)

    Shannak, B.; Corsmeier, U.; Kottmeier, Ch.; Al-azab, T.

    2014-12-01

    Due to the lack of data by large dust and sand particle, the fluid dynamics characteristics, hence the collection efficiencies of different twelve dust samplers have been experimentally investigated. Wind tunnel tests were carried out at wind velocities ranging from 1 up to 5.5 ms-1. As a large solid particle of 0.5 and 1 mm in diameter, Polystyrene pellets called STYRO Beads or polystyrene sphere were used instead of sand or dust. The results demonstrate that the collection efficiency is relatively acceptable only of eight tested sampler and lie between 60 and 80% depending on the wind velocity and particle size. These samplers are: the Cox Sand Catcher (CSC), the British Standard Directional Dust Gauge (BSD), the Big Spring Number Eight (BSNE), the Suspended Sediment Trap (SUSTRA), the Modified Wilson and Cooke (MWAC), the Wedge Dust Flux Gauge (WDFG), the Model Series Number 680 (SIERRA) and the Pollet Catcher (POLCA). Generally they can be slightly recommended as suitable dust samplers but with collecting error of 20 up to 40%. However the BSNE verify the best performance with a catching error of about 20% and can be with caution selected as a suitable dust sampler. Quite the contrary, the other four tested samplers which are the Marble Dust Collector (MDCO), the United States Geological Survey (USGS), the Inverted Frisbee Sampler (IFS) and the Inverted Frisbee Shaped Collecting Bowl (IFSCB) cannot be recommended due to their very low collection efficiency of 5 up to 40%. In total the efficiency of sampler may be below 0.5, depending on the frictional losses (caused by the sampler geometry) in the fluid and the particle's motion, and on the intensity of airflow acceleration near the sampler inlet. Therefore, the literature data of dust are defective and insufficient. To avoid false collecting data and hence inaccurate mass flux modeling, the geometry of the dust sampler should be considered and furthermore improved.

  14. Characteristics of cobalt removal by crab shell particles

    International Nuclear Information System (INIS)

    The characteristics of cobalt removal by raw crab shell particles was investigated. The removal efficiency of cobalt was dependent on contact time, solution pH, crab shell dose and ionic strength. Approximately 99% of the cobalt was removed within 6 hour after contact with crab shell particles. The removal efficiency was slightly affected by initial solution pH over 5.0 and the final solution pH changed to 10 spontaneously. In addition, optimum [H range of cobalt removal was broaden by the effect of crab shell addition. Maximum uptake of cobalt was 510 mg Co/g crab shell at initial pH 5.0. The removal efficiency was affected slightly by ionic strength up to 2.0 M of NaCl. From the results of scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), the removal of cobalt by crab shell was mainly through the dissolution of CaCO3 followed by precipitation of Co(OH)2 and CoCO3 and then the precipitates were adsorbed to the chitin on the surface of crab shell particles. Compared to the results with activated carbon column, the addition of crab shell to activated carbon column increased the removal efficiency dramatically.(author)

  15. Limitations in the Use of Unipolar Charging for Electrical Mobility Sizing Instruments: A Study of the Fast Mobility Particle Sizer

    DEFF Research Database (Denmark)

    Levin, Marcus; Gudmundsson, A.; Pagels, J. H.;

    2015-01-01

    A comparison between three different types of particle sizing instruments (fast mobility particle sizer, FMPS; electrical low pressure impactor, ELPI; and scanning mobility particle sizer, SMPS) and one condensation particle counter (CPC) was made to compare instrument response in terms of size...... distributions and number concentration. Spherical oil droplets in 39 different sizes, with geometric mean diameter (GMD) ranging from 50nm to 820nm, were used as test particles. Furthermore, a characterization of the FMPS unipolar charger behavior was made to analyze the measured size distributions and number...... concentrations. The results show that all three sizing-instruments agree well for particle sizes below 200nm, both in terms of size and number concentration, but the FMPS deviates clearly when particle sizes exceed 200nm. Above this, the FMPS underestimates the particle size throughout the remainder of the size...

  16. Based on particle size distribution of radioactive aerosol of screen diffusion battery measuring software

    International Nuclear Information System (INIS)

    Based on screen diffusion battery of particle size distribution of the radioactive aerosol measuring system developed a measurement and analysis software, the software operating environment was the embedded ARM-based hardware system and embedded linux operating system. The software is developed by the open source package QT. System functions included the measurement process control, screen diffusion battery transmittance calculations, particle size distribution measurement, measurement data analysed by the EM algorithm and Twomey algorithms, particle size distribution showed, system communication and other functions. (authors)

  17. Measurements of Particle Size Distribution Based on Mie Scattering Theory and Markov Chain Inversion Algorithm

    Directory of Open Access Journals (Sweden)

    Zi Ye

    2012-10-01

    Full Text Available Measuring particle size distribution through calculating light scattering intensity is a typical inverse problem. This paper builds an inverse mathematical model based on Mie scattering, deduces the inversion formulas for particle size, and calculates the relative coefficients through programming with built-in functions in MATLAB. In order to improve the accuracy and noise immunity of particle size distribution measurement, the development of stochastic inversion algorithm: an inverse problem model based on Markov chain algorithm is proposed. Results of numerical simulation are added acceptable noise indicate that the algorithm of Markov chain has strong noise immunity and can meet the requirements of on-line measurement.

  18. Effect of particle size and temperature on volatiles produced from coal by slow pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Morris, R.M. (University of Durban-Westville, Durban (South Africa). Dept. of Chemical Engineering)

    1990-06-01

    Pyrolysis runs were carried out in the temperature range 1000-1150{degree}C and the particle size range +38 {mu}m to -2360{mu}m on a semianthracite coal from the Welgedacht area. Correlations were established for the yields of hydrogen and methane as functions of particle size and final temperature, and for carbon monoxide and carbon dioxide as a function of particle size at a final temperature before decomposition of carbonates in the mineral matter. The observations are explained in terms of secondary reactions occurring in the diffusion of the primary products through the pores of the char. 10 refs., 6 figs., 4 tabs.

  19. Size measurement of nano-particles using self-mixing effect

    Institute of Scientific and Technical Information of China (English)

    Huarui Wang; Jianqi Shen

    2008-01-01

    In this letter, the technique of laser self-mixing effect is employed for nano-particle size analysis. In contrast to the photon correlation spectroscopy (PCS) and photon cross correlation spectroscopy (PCCS),the main advantages of this technique are sensitive, compact, low-cost, and simple experimental setup etc.An improved Kaczmarz projection method is developed in the inversion problem to extract the particle size distribution. The experimental results prove that nano-particle size can be measured reasonably by using the self-mixing effect technique combined with the improved projection algorithm.

  20. Atomic-Scale Modeling of Particle Size Effects for the Oxygen Reduction Reaction of Pt

    DEFF Research Database (Denmark)

    Tritsaris, Georgios; Greeley, Jeffrey Philip; Rossmeisl, Jan;

    2011-01-01

    both the specific and mass activities for particle sizes in the range between 2 and 30 nm. The mass activity is calculated to be maximized for particles of a diameter between 2 and 4 nm. Our study demonstrates how an atomic-scale description of the surface microstructure is a key component in...... understanding particle size effects on the activity of catalytic nanoparticles.......We estimate the activity of the oxygen reduction reaction on platinum nanoparticles of sizes of practical importance. The proposed model explicitly accounts for surface irregularities and their effect on the activity of neighboring sites. The model reproduces the experimentally observed trends in...

  1. Faecal particle-size distribution from ewes fed grass silages harvested at different stages of maturity

    DEFF Research Database (Denmark)

    Jalali, Alireza; Nørgaard, Peder; Nadeau, E.;

    2008-01-01

    The aim of this experiment was to study the effect of maturity stage of grass at harvest on particle size in faeces from ewes fed grass silage ad libitum. Eighteen pregnant Swedish ewes bearing two foetuses were given one of three treatments as their only feed. The treatments were early (ECS...... pore size. The proportions of particles in the B, C, D, S and O fractions were affected by cutting time of the silaage (P < 0.003). In conclusion, stage of maturity at harvest strongly affects the distribution of particle size in faeces from ewes fed grass silages....

  2. Laser tweezers: spectroscopy of optically trapped micron-sized particles

    International Nuclear Information System (INIS)

    Information is often obtained about biological systems by analysis of single cells in the system. The optimum conditions for this analysis are when the cells are living and in their natural surroundings as they will be performing their normal functions and interactions. Analysis of cells can be difficult due to their mobility. Laser tweezing is a non contact method that can be employed to overcome this problem and provides a powerful tool in the analysis of functions and interactions at single cell level. In this investigation Raman spectra of a molecule of β - carotene, dissolved in microdroplets of oil was obtained. The droplets were trapped using Nd-YAG beam and a low intensity Ar+ beam was used to analyse the trapped particles. 2 refs., 5 figs

  3. 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.

  4. An optical particle size spectrometer for aircraft-borne measurements in IAGOS-CARIBIC

    Science.gov (United States)

    Hermann, Markus; Weigelt, Andreas; Assmann, Denise; Pfeifer, Sascha; Muller, Thomas; Conrath, Thomas; Voigtlander, Jens; Heintzenberg, Jost; Wiedensohler, Alfred; Martinsson, Bengt G.; Deshler, Terry; Brenninkmeijer, Carl A. M.; Zahn, Andreas

    2016-05-01

    The particle number size distribution is an important parameter to characterize the atmospheric aerosol and its influence on the Earth's climate. Here we describe a new optical particle size spectrometer (OPSS) for measurements of the accumulation mode particle number size distribution in the tropopause region on board a passenger aircraft (IAGOS-CARIBIC observatory: In-service Aircraft for a Global Observing System - Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container). A modified KS93 particle sensor from RION Co., Ltd., together with a new airflow system and a dedicated data acquisition system, is the key component of the CARIBIC OPSS. The instrument records individual particle pulse signal curves in the particle size range 130-1110 nm diameter (for a particle refractive index of 1.47-i0.006) together with a time stamp and thus allows the post-flight choice of the time resolution and the size distribution bin width. The CARIBIC OPSS has a 50 % particle detection diameter of 152 nm and a maximum asymptotic counting efficiency of 98 %. The instrument's measurement performance shows no pressure dependency and no particle coincidence for free tropospheric conditions. The size response function of the CARIBIC OPSS was obtained by a polystyrene latex calibration in combination with model calculations. Particle number size distributions measured with the new OPSS in the lowermost stratosphere agreed within a factor of 2 in concentration with balloon-borne measurements over western North America. Since June 2010 the CARIBIC OPSS is deployed once per month in the IAGOS-CARIBIC observatory.

  5. Influence of Particle Size on Magnetic Properties of Soils in Zhejiang Province, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The relationship between magnetic properties and particle size of soils derived from metamorphic rock,basalt, granite, Quaternary red clay, limestone and mudstone from Zhejiang Province, East China was stu died. Based on the variations of the mass magnetic susceptibility (x), anhysteretic remanent magnetization (ARM), and saturation isothermal remanent magnetizatization (SIRM) with soil particle size, the relationship could be classified into three groups. For the soils derived from metamorphic rock and basalt, magnetic values were the highest in the gravel and coarse sand fractions and decreased with decreasing soil particle size. The soils derived from sedimentary rock had a bimodal distribution of magnetic values, with peaks in 1~0.5 and 0.005~0.000 5 mm fractions. The soil developed on granite was characterized by a peak of magnetic valuein 0.001~0.000 5 mm fractions. Frequency-dependent susceptibility (xfd) and ratios of magnetic parameters (ARM/x, SIRM/x and SIRM/ARM) of soil particle fractions showed that variations in ferrimagnetic grainsize paralleled those in particle size. xfd peaked in clay fraction and decreased with increasing particle size,irrespective of soil parent materials. The acquisition curves of IRM and demagnetization parameter of different soil particles indicated that there were different agnetic minerals assemblages in different particle fractions..

  6. 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.

  7. Narrowly size-distributed cobalt salt containing poly(2-hydroxyethyl methacrylate) particles by inverse miniemulsion.

    Science.gov (United States)

    Cao, Zhihai; Wang, Zhuo; Herrmann, Christine; Ziener, Ulrich; Landfester, Katharina

    2010-05-18

    Cobalt-containing hybrid particles have been prepared through the encapsulation of cobalt tetrafluoroborate hexahydrate (CoTFB) via inverse miniemulsion polymerization of 2-hydroxyethyl methacrylate (HEMA). We systematically varied the amount and type of cosolvent (water, methanol, ethanol, ethylene glycol), apolar continuous phase (cyclohexane, isooctane, isopar M, hexadecane), amount of cobalt salt, and molecular weight of the polymeric surfactant. The influence of those parameters on the particle size, size distribution, and particle morphology were investigated. Narrowly size-distributed hybrid particles with good colloidal stability could be obtained in a wide range of cobalt content between 5.7 and 22.6 wt % salt relative to the monomer. The addition of a cosolvent such as water not only promotes the loading of metal salt but also has a positive influence on narrowing the particle size distribution. We assume that generally narrowly size-distributed particles can be obtained for a large variety of combinations of polar/apolar phase by adjusting the balance between osmotic and Laplace pressure via the solubility of the metal salt in the continuous phase and lowering the interfacial tension by adjusting the hydrophilic-lipophilic balance (HLB) value of the surfactant. The results show a significant advantage of the inverse miniemulsion over the direct system with respect to the variability and total amount of metal salt without losing the narrow particle size distribution and colloidal stability. PMID:20112941

  8. Preparation and characterization of micrometer-sized ice particles for planetary-science experiments

    CERN Document Server

    Gundlach, Bastian; Beitz, Eike; Blum, Jürgen

    2011-01-01

    Coagulation models assume a higher sticking threshold for micrometer-sized ice particles than for micrometer-sized silicate particles. However, in contrast to silicates, laboratory investigations of the collision properties of micrometer-sized ice particles (in particular, of the most abundant water ice) have not been conducted yet. Thus, we established two different experimental methods to produce micrometer-sized water ice particles, i. e. by spraying water droplets into liquid nitrogen an by spraying water droplets into a cold nitrogen atmosphere. We found that the size of the ice particles, produced with the different methods, are very similar (arithmetic means of the particle radii for the two different methods: (1.49+-0.79) micrometer and (1.45+-0.65) micrometer, respectively). Ice aggregates composed of the micrometer-sized ice particles are highly porous (volume filling factor: 0.11+-0.01) or rather compact (volume filling factor: 0.72+-0.04), depending on the method of production. Furthermore, a roll...

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

    International Nuclear Information System (INIS)

    It has been desired to eliminate or collect the contamination particles of radioisotope in each sort of species or shape and size non-invasively. The shape and size of particle can be determined from the shape and distribution of diffraction pattern of particle in the parallel laser beam, the species of particle can be discriminated by the fluorescence from resonance of laser beam, or by the laser Raman scattering, and the particle suspended in the air or falling down in a vacuum can be levitated against the gravity and trapped by the radiation force and the trapping force of the focussed laser beam in the atmosphere or in a vacuum. For the purpose of the non-invasive manipulation of contamination particles, the laser manipulation technique, image processing technique with Multiplexed Matched Spatial Filter and the determination technique of laser Raman scattering or fluorescence from resonance of laser light were combined in the experiments. The shape, size and species of particles trapped in the focal plane of focused Ar laser beam can be determined simultaneously and instantaneously from the shape and intensity distributions of diffraction patterns of the particles in the irradiation of parallel coherent beam of He-Ne laser, and fluorescence from the resonance of YAG laser beam with variable wave length. In this research, a new technique is proposed to manipulate non-invasively the contamination particles determined with the shape, size and species in the atmosphere or in a vacuum, by laser beam. (author)

  10. (99m)Tc-human serum albumin nanocolloids: particle sizing and radioactivity distribution.

    Science.gov (United States)

    Persico, Marco G; Lodola, Lorenzo; Buroni, Federica E; Morandotti, Marco; Pallavicini, Piersandro; Aprile, Carlo

    2015-07-01

    Several parameters affect the biodistribution of administered nanocolloids (NC) for Sentinel Lymph Node (SLN) detection: particle size distribution, number of Tc atoms per particle and specific activity (SA). Relatively few data are available with frequently conflicting results. (99m)Tc-NC-human serum albumin (HSA) Nanocoll®, Nanoalbumon® and Nanotop® were analysed for particles' dimensional and radioactivity distribution, and a mathematical model was elaborated to estimate the number of particles involved. Commercially available kits were reconstituted at maximal SA of 11 MBq/µg HSA. Particles size distribution was evaluated by Dynamic Light Scattering. These data were related to the radioactivity distribution analysis passing labelled NC through three polycarbonate filters (15-30-50-nm pore size) under vacuum. Highest radioactivity was carried by 30-50 nm particles. The smallest ones, even though most numerous, carried only the 10% of (99m)Tc atoms. Nanocoll and Nanotop are not significantly different, while Nanoalbumon is characterized by largest particles (>30 nm) that carried the most of radioactivity (80%). Smallest particles could saturate the clearing capacity of macrophages; therefore, if the tracer is used for SLN detection, more node tiers could be visualized, reducing accuracy of SLN mapping. Manufacturers could implement technical leaflets with particle size distribution and could improve the labelling protocol to provide clinicians useful information. PMID:26198778

  11. Critical conditions for particle motion in coarse bed materials of nonuniform size distribution

    Science.gov (United States)

    Bathurst, James C.

    2013-09-01

    Initiation of particle motion in a bed material of nonuniform size distribution may be quantified by (qci/qcr) = (Di/Dr)b, where qci is the critical unit discharge at which particle size Di enters motion, qcr is the critical condition for a reference size Dr unaffected by the hiding/exposure effects associated with nonuniform size distributions, i and r refer to percentiles of the distribution and b varies from 0 (equal mobility in entrainment of all particle sizes) to 1.5-2.5 (full size selective transport). Currently there is no generally accepted method for predicting the value of b. Flume and field data are therefore combined to investigate the above relationship. Thirty-seven sets of flume data quantify the relationship between critical unit discharge and particle size for bed materials with uniform size distributions (used here to approximate full size selective transport). Field data quantify the relationship for bed materials of nonuniform size distribution at 24 sites, with b ranging from 0.15 to 1.3. Intersection of the two relationships clearly demonstrates the hiding/exposure effect; in some but not all cases, Dr is close to the median size D50. The exponent has two clusters of values: b > 1 for sites subject to episodic rain-fed floods and data collected by bedload pit trap and tracers; and b 1, sites with relatively infrequent bedload transport where particle embedding and consolidation could reduce the mobility of coarser particles; and, for b firm evidence for such a dependency on bed structure but variations in b could potentially be caused by factors outside those determining equal mobility or size selection but appearing to affect b in the same way.

  12. Values of Particle Size, Particle Density and Slurry Viscosity to use in Waste Feed Delivery Transfer System Analysis

    International Nuclear Information System (INIS)

    The objective of this document is to provide recommended values for three waste properties to be used in a planned revision of the Waste Feed Delivery Transfer System Analysis (Julyk et al. 2001). These properties are particle size distribution (PSD), particle density, and slurry viscosity. In this document, the results of laboratory and engineering studies will be collated and summarized to provide a succinct source of physical property data for use in the hydraulic analysis of the transfer system

  13. Particle size analysis of coal and lime stone used in fbc power plant lakhra

    International Nuclear Information System (INIS)

    Pakistan is gifted with huge coal reserves throughout its land from Sindh to NWFP province. The total reserves at Lakhra have been estimated to be 1328 million tones. Average annual production of coal from Lakhra is over one million tones. Most of this production is used in the WAPDA power plant at Khanot, Sindh and in brick kiln industry. The high sulphur content coal has been used in the FBC (Fluidized Bed Combustor) power plant at Lakhra. The coal and limestone have been used ill power plant at Lakhra are 52 and 26 tones/hr as per stoichiometric calculations respectively. The research shows that for complete combustion of high sulphur content coal and reducing the emission, the particles size of coal and limestone is of utmost importance. The particle sizes of coal and limestone have been analyzed. The result is then compared with the required particle size as per design parameters of FBC at Lakhra (coal and lime stone 13 and 6.0 mm). The result shows that the particle size of the coal and limestone is not being as per design parameter of the FBC. The coal and lime stone particles size used in FBC is from 0.075-4.75 that is much lower than the particle size of 13 and 6 mm as per design specification. In addition the particle size analysis was also carried out for the fly ash, bottom ash and re-injected material (un-burnt material from the FBC that is recycled to the FBC as per plant specification) to evaluate the overall performance of the FBC plant in terms of Maintenance and Operational problems. As a result of deviation of particle size of coal and limestone from the recommended size, the combustion of coal is not complete. The incomplete combustion not only reduces the plant efficiency and capacity but various operational and technical problems occurs that even result regular shut down of the power plant. (author)

  14. Preparation of Nano-Sized TiO2 Particles by Microemulsion Method

    Institute of Scientific and Technical Information of China (English)

    Shaohua Zhang; Bing Xie; Fengyi Li; Peng Xu

    2006-01-01

    Nano-sized titania powders have been prepared by hydrolysis of tetrabutyl titanate in the droplet of water/OP-7/pentanol/cyclohexane microemulsion system. The effects of ingredient change on the water drop size and particle size were investigated. The prepared TiO2 was in the form of anatase after annealing. TiO2 was characterized by TG-TGA,FTIR, XRD to measure the transformation temperature, surface adsorption and average size.

  15. Changes in silver nanoparticles exposed to human synthetic stomach fluid: Effects of particle size and surface chemistry

    International Nuclear Information System (INIS)

    The significant rise in consumer products and applications utilizing the antibacterial properties of silver nanoparticles (AgNPs) has increased the possibility of human exposure. The mobility and bioavailability of AgNPs through the ingestion pathway will depend, in part, on properties such as particle size and the surface chemistries that will influence their physical and chemical reactivities during transit through the gastrointestinal tract. This study investigates the interactions between synthetic stomach fluid and AgNPs of different sizes and with different capping agents. Changes in morphology, size and chemical composition were determined during a 30 min exposure to synthetic human stomach fluid (SSF) using Absorbance Spectroscopy, High Resolution Transmission Electron and Scanning Electron Microscopy (TEM/SEM), Dynamic Light Scattering (DLS), and Nanoparticle Tracking Analysis (NTA). AgNPs exposed to SSF were found to aggregate significantly and also released ionic silver which physically associated with the particle aggregates as silver chloride. Generally, the smaller sized AgNPs (< 10 nm) showed higher rates of aggregation and physical transformation than larger particles (75 nm). Polyvinylpyrrolidone (pvp)-stabilized AgNPs prepared in house behaved differently in SSF than particles obtained from a commercial source despite having similar surface coating and size distribution characteristics. - Highlights: ► Interactions between synthetic stomach fluid (SSF) and silver nanoparticles (AgNPs) are described. ► AgNPs exposed to SSF aggregate and silver chloride are associated with the particle aggregates. ► Smaller AgNPs (< 10 nm) showed higher rates of aggregation and transformation than larger particles (75 nm). ► Polyvinylpyrrolidone-stabilized AgNPs obtained from different sources aggregated at different rates when exposed to SSF

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  17. Removal of Cryptosporidium sized particle under different filtration temperature, flow rate and alum dosing

    Institute of Scientific and Technical Information of China (English)

    XU Guo-ren; Fitzpatrick S. B. Caroline; Gregory John; DENG Lin-yu

    2007-01-01

    Recent Cryptosporidium outbreaks have highlighted concerns about filter efficiency and in particular particle breakthrough. It is essential to ascertain the causes of Cryptosporidium sized particle breakthrough for Cryptosporidium cannot be destroyed by conventional chlorine disinfection. This research tried to investigate the influence of temperature, flow rate and chemical dosing on particle breakthrough during filtration. The results showed that higher temperatures and coagulant doses could reduce particle breakthrough. The increase of filtration rate made the residual particle counts become larger. There was an optimal dose in filtration and was well correlated to ζ potential.

  18. Characterization of macromolecular complexes in red wine: Composition, molecular mass distribution and particle size.

    Science.gov (United States)

    Bindon, Keren A; Carew, Anna L; Mierczynska-Vasilev, Agnieszka; Kassara, Stella; Kerslake, Fiona; Smith, Paul A

    2016-05-15

    Precipitates were prepared from two compositionally different Pinot noir wines with addition of excess ethanol, and contained primarily polysaccharide, tannin and protein. The ethanol-soluble material was further fractionated into polymeric (tannin) and monomeric phenolics. Tannin associated with precipitates was of a higher molecular mass than that remaining in ethanolic solution. Wine fractions were reconstituted at the ratios of the original wine and analyzed using nanoparticle tracking analysis. The average particle size of the tannin fraction was 75-89 nm, and increased when combined with the precipitate (≅ 200 nm). Addition of the monomeric fraction to the tannin-precipitate complex increased both the incidence and concentration of smaller particles, reducing the average particle size. The formation of aggregates occurred in all fractions and only minor differences in particle size distribution were found between wines. Differences in particle concentration between wines appear to be due to differences in the total concentration of macromolecules rather than compositional differences. PMID:26776042

  19. The effect of particle size distributions on the microstructural evolution during sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Tikare, V.; Frandsen, Henrik Lund;

    2013-01-01

    Microstructural evolution and sintering behavior of powder compacts composed of spherical particles with different particle size distributions (PSDs) were simulated using a kinetic Monte Carlo model of solid state sintering. Compacts of monosized particles, normal PSDs with fixed mean particle...... PSDs, but the final grain sizes were smaller. These behaviors are explained by the smallest grains in the broader PSDs being consumed very quickly by larger neighboring grains. The elimination of the small grains reduces both the total number of necks and the neck area between particles, which in turn...... reduces the regions where vacancies can be annihilated, leading to slower densification rates. The loss of neck area causes grain growth by surface diffusion to become the dominant microstructural evolution mechanism, leading to poor densification. Finally, pore size was shown to increase with the width...

  20. Deposition and clearance of monodisperse aerosols in the calf lung: effects of particle size and a mucolytic agent (bromhexine)

    Science.gov (United States)

    Davies, C P; Webster, A J

    1987-01-01

    Mucociliary clearance and retention of monodisperse aerosols of radiolabelled polystyrene particles of both 3.3 microns and 5 microns diameter were investigated in four healthy calves and two sick calves. The effect of the mucolytic agent bromhexine was also assessed at two dosage levels. There were significant differences (P less than 0.05) in clearance rate constant between calves, but similar patterns of clearance for each calf. These characteristics of mechanical lung clearance did not vary over a two month period. Values of clearance rate constant and percentage retention varied significantly (P less than 0.001) between the two different particle sizes, 5 microns particles giving faster clearance and lower retention of particles than 3.3 microns particles. Bromhexine at the recommended dose of 1.6 mg/kg 0.75 caused a significant (P less than 0.05) increase in clearance rate in both healthy and sick calves, but affected percentage retention only in sick calves. This study illustrates the variation in mucociliary clearance rates shown by individuals and also underlines the importance of particle size in aerosols used for studies of pulmonary deposition and clearance. The work also indicates that bromhexine may be of use in the therapy of respiratory disease in calves. PMID:3651885

  1. Studies on the Effects of RDX Particle Size on the Burning Rate of Gun Propellants

    Directory of Open Access Journals (Sweden)

    A.G.S. Pillai

    1996-04-01

    Full Text Available The ballistic properties of RDX-based propellants are highly dependent on the particle size of RDX used. The effect of RDX particle size on the burning rate and pressure exponent of the gun propellant was studied. Propellant formulation containing RDX to extent of 60 per cent in the composition was processed with varying particle size of RDX. Finished propellants in heptatubular and cord geometry were evaluated for ballistic aspects by closed vessel firing in a 700 cc vessel at a loading density of 0.18 g/cc. The data obtained clearly indicate that increase in particle size of RDX increases the burning rate as well as the pressure exponent.

  2. Particle Size Distribution, Powder Agglomerates and Their Effects on Sinterability of Ultrafine Alumina Powders

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An intensive study of the particle size distribution of four commercial ultrafine alumina powders to obtain information about the powder agglomeration and relate them to the compactibility and the sinterability has been made.

  3. Regression modeling of particle size distributions in urban storm water: advancements through improved sample collection methods

    Science.gov (United States)

    Fienen, Michael N.; Selbig, William R.

    2012-01-01

    A new sample collection system was developed to improve the representation of sediment entrained in urban storm water by integrating water quality samples from the entire water column. The depth-integrated sampler arm (DISA) was able to mitigate sediment stratification bias in storm water, thereby improving the characterization of suspended-sediment concentration and particle size distribution at three independent study locations. Use of the DISA decreased variability, which improved statistical regression to predict particle size distribution using surrogate environmental parameters, such as precipitation depth and intensity. The performance of this statistical modeling technique was compared to results using traditional fixed-point sampling methods and was found to perform better. When environmental parameters can be used to predict particle size distributions, environmental managers have more options when characterizing concentrations, loads, and particle size distributions in urban runoff.

  4. Size-selective separation of DNA fragments by using lysine-functionalized silica particles

    Science.gov (United States)

    Liu, Lingling; Guo, Zilong; Huang, Zhenzhen; Zhuang, Jiaqi; Yang, Wensheng

    2016-02-01

    In this work, a facile and efficient approach has been demonstrated for size-selective separation of DNA fragments by using lysine-functionalized silica particles. At a given pH, the environmental ionic strength can be utilized to alter the electrostatic interactions of lysine-functionalized silica particles with DNA fragments and in turn the DNA fragments on the silica particle surfaces, which exhibits a clear dependence on the DNA fragment sizes. By carefully adjusting the environmental pH and salt concentration, therefore, the use of the lysine-functionalized silica particles allows effective separation of binary and ternary DNA mixtures, for example, two different DNA fragments with sizes of 101 and 1073 bp, 101 and 745 bp, 101 and 408 bp, respectively, and three different DNA fragments with sizes of 101, 408 and 1073 bp.

  5. Magnetic properties in an ash flow tuff with continuous grain size variation: a natural reference for magnetic particle granulometry

    Science.gov (United States)

    Till, J.L.; Jackson, M.J.; Rosenbaum, J.G.; Solheid, P.

    2011-01-01

    The Tiva Canyon Tuff contains dispersed nanoscale Fe-Ti-oxide grains with a narrow magnetic grain size distribution, making it an ideal material in which to identify and study grain-size-sensitive magnetic behavior in rocks. A detailed magnetic characterization was performed on samples from the basal 5 m of the tuff. The magnetic materials in this basal section consist primarily of (low-impurity) magnetite in the form of elongated submicron grains exsolved from volcanic glass. Magnetic properties studied include bulk magnetic susceptibility, frequency-dependent and temperature-dependent magnetic susceptibility, anhysteretic remanence acquisition, and hysteresis properties. The combined data constitute a distinct magnetic signature at each stratigraphic level in the section corresponding to different grain size distributions. The inferred magnetic domain state changes progressively upward from superparamagnetic grains near the base to particles with pseudo-single-domain or metastable single-domain characteristics near the top of the sampled section. Direct observations of magnetic grain size confirm that distinct transitions in room temperature magnetic susceptibility and remanence probably denote the limits of stable single-domain behavior in the section. These results provide a unique example of grain-size-dependent magnetic properties in noninteracting particle assemblages over three decades of grain size, including close approximations of ideal Stoner-Wohlfarth assemblages, and may be considered a useful reference for future rock magnetic studies involving grain-size-sensitive properties.

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

    Science.gov (United States)

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

    2016-06-01

    Micron-sized polymer particles with nanoscale metal coatings are essential in conductive adhesives for electronics assembly. The particles function in a compressed state in the adhesives. The link between mechanical properties and electrical conductivity is thus of the utmost importance in the formation of good electrical contact. A custom flat punch set-up based on nanoindentation has been developed to simultaneously deform and electrically probe individual particles. The set-up has a sufficiently low internal resistance to allow the measurement of sub-Ohm contact resistances. Additionally, the set-up can capture mechanical failure of the particles. Combining this data yields a fundamental understanding of contact behavior. We demonstrate that this method can clearly distinguish between particles of different sizes, with different thicknesses of metal coating, and different metallization schemes. The technique provides good repeatability and physical insight into the behavior of these particles that can guide adhesive design and the optimization of bonding processes.

  7. Measuring shape and size of micrometric particles from the analysis of the forward scattered field

    Science.gov (United States)

    Villa, S.; Sanvito, T.; Paroli, B.; Pullia, A.; Delmonte, B.; Potenza, M. A. C.

    2016-06-01

    Characterizing nano- and micro-particles in fluids still proves to be a significant challenge for both science and industry. Here, we show how to determine shape and size distributions of polydisperse water suspensions of micron-sized particles by the analysis of the field scattered in the forward direction by single particles illuminated by a laser beam. We exploit the novel Single Particle Extinction and Scattering method in connection with shear conditions which give preferred orientations to the particles passing through the scattering volume. Water suspensions of calibrated non-spherical particles, polydisperse standard monophasic mineral samples of quartz and kaolinite, and a mixture of quartz and illite are studied in detail. Application and limitation of the method are discussed.

  8. Single particle optical sizing; aggregation of polystyrene latices by salt and polymer.

    OpenAIRE

    Pelssers, E.G.M.

    1988-01-01

    The subject of this thesis is the development of a Single Particle Optical Sizer (SPOS) which is capable of measuring in detail discrete particle size distributions in the colloidal size range. With this instrument we studied the aggregation of latices induced by polymer and salt, and found evidence for non-equilibrium flocculation.Chapter 2 is an inventory of the existing methods of measuring aggregation. A comparison is made with our SPOS instrument. The techniques are classified into three...

  9. Statistical estimation of stratospheric particle size distribution by combining optical modelling and lidar scattering measurements

    OpenAIRE

    J. Jumelet; S. Bekki; David, C.; P. Keckhut

    2008-01-01

    A method for estimating the stratospheric particle size distribution from multiwavelength lidar measurements is presented. It is based on matching measured and model-simulated backscatter coefficients. The lidar backscatter coefficients measured at the three commonly used wavelengths 355, 532 and 1064 nm are compared to a precomputed look-up table of model-calculated values. The optical model assumes that particles are spherical and that their size distribution is unimodal. ...

  10. Size-Segregated Particle Number Concentrations and Respiratory Emergency Room Visits in Beijing, China

    OpenAIRE

    Leitte, Arne Marian; Schlink, Uwe; Herbarth, Olf; Wiedensohler, Alfred; Pan, Xiao-Chuan; Hu, Min; Richter, Matthia; Wehner, Birgit; TUCH Thomas; Wu, Zhijun; Yang, Minjuan; Liu, Liqun; Breitner, Susanne; Cyrys, Josef; Peters, Annette

    2010-01-01

    Background The link between concentrations of particulate matter (PM) and respiratory morbidity has been investigated in numerous studies. Objectives The aim of this study was to analyze the role of different particle size fractions with respect to respiratory health in Beijing, China. Methods Data on particle size distributions from 3 nm to 1 μm; PM10 (PM ≤ 10 μm), nitrogen dioxide (NO2), and sulfur dioxide concentrations; and meteorologic variables were collected daily from March 2004 to De...

  11. Optimization of regularization parameter of inversion in particle sizing using light extinction method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In particle sizing by light extinction method, the regularization parameter plays an important role in applying regularization to find the solution to ill-posed inverse problems. We combine the generalized cross-validation (GCV) and L-curve criteria with the Twomey-NNLS algorithm in parameter optimization. Numerical simulation and experimental validation show that the resistance of the newly developed algorithms to measurement errors can be improved leading to stable inversion results for unimodal particle size distribution.

  12. CALCIUM HYDROXIDE AND CALCIUM CARBONATE PARTICLE SIZE EFFECTS ON REACTIVITY WITH SULFUR DIOXIDE

    Science.gov (United States)

    The paper reports results of measurements of the effect of in situ calcium-based sorbent particle size upon reactivity with 3000 ppm SO2 in an 1100 c drop-tube furnace, using on-line collection of the reacted sorbent with a particle cascade impactor. Significant agglomeration occ...

  13. Methotrexate intercalated layered double hydroxides with different particle sizes: structural study and controlled release properties.

    Science.gov (United States)

    Zhang, Xiao-Qing; Zeng, Mei-Gui; Li, Shu-Ping; Li, Xiao-Dong

    2014-05-01

    To study the influence of particle size on release properties, drug efficacy and other properties, a series of methotrexate intercalated layered double hydroxides (MTX/LDHs) nanohybrids with different particle sizes were synthesized through traditional coprecipitation method, by using the mixture of water and polyethylene glycol (volume ratio is 3:1) as solvent. The relationship between particle size and hydrothermal treatment conditions (i.e., time and temperature) had been systematically investigated, and the results indicate that the particle size can be precisely controlled between 70 and 300 nm. Elemental C/H/N and inductive coupled plasma (ICP) analysis indicated that different hydrothermal treatment almost has no effect on compositions of the nanohybrids. X-ray diffraction (XRD) patterns and fourier transform infrared spectroscopy (FTIR) investigations manifested the successful intercalation of MTX anions. MTX/LDHs particles exhibited hexagonal platelet morphology with round corner, due to the adsorption of MTX anions on positively charged LDHs surface. In addition, the crystallinity of MTX/LDHs increased with the particle diameters and the thermal stability of MTX anions was enhanced by holding together with LDHs layers. The in vitro release showed that bigger particles have much longer release duration, and the bioassay tests indicated that bigger particles are more efficient in the suppression of the tumor cells. PMID:24632036

  14. Particle size matters : diagnostics and treatment of small airways involvement in asthma

    NARCIS (Netherlands)

    Cohen, J; Postma, D S; Douma, W R; Vonk, J M; De Boer, A H; ten Hacken, N H T

    2011-01-01

    Small airways are an important site of inflammation and obstruction in asthma, which contributes to the severity of airway hyperresponsiveness (AHR) that is usually measured by nebulisation of large-particle stimuli. We investigated whether small and large particle sizes of aerosolised adenosine mon

  15. Particle characteristics of different materials after ultra-short pulsed laser (USPL) irradiation

    Science.gov (United States)

    Meister, Joerg; Schelle, Florian; Kowalczyk, Philip; Frentzen, Matthias

    2012-01-01

    The exposition of nanoparticles caused by laser application in dental health care is an open discussion. Based on the fact that nanoparticles can penetrate through the mucosa, the knowledge about particle characteristics after irradiation with an USPL is of high importance. Therefore, the aim of this study was to investigate the particle characteristics, especially the size of the ablated debris after USPL irradiation. The irradiation was carried out with an USP Nd:YVO4 laser with a center wavelength of 1064 nm. Based on the pulse duration of 8 ps and a pulse repetition rate of 500 kHz the laser emits an average power of 9 W. The materials investigated were dental tissues and dental restorative materials (composite and amalgam), ceramic and different metals (gold and aluminium). The samples were irradiated with a power density in the order of 300 GW/cm2 at distances of 5, 10, 15, and 20 mm. The debris was collected on an object plate. SEM pictures were used for analysis of the ablation debris. Depending on the irradiated material, we observed different kinds of structures: vitreous, flocculent, and pellet-like. The mean particle sizes were 10 x 10 up to 30 x 30 μm2. In addition, a cluster of ablated matter (nanometer range) distributed over the whole irradiated area was found. With increasing distances the cluster structure reduced from multi-layer to mono-layer clusters. Particle sizes in the micrometer and nanometer range were found after irradiation with an USPL. The nanoparticles create a cluster structure which is influenced by increasing distances.

  16. A method for detecting the presence of organic fraction in nucleation mode sized particles

    OpenAIRE

    Vaattovaara, P.; Räsänen, M.; Kühn, T.; Joutsensaari, J.; Laaksonen, a

    2005-01-01

    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 organic fraction in the nucleation mode size class in differ...

  17. Micro-Sized Particle Production of Momordicas sp Extract Using Spray Dryer

    OpenAIRE

    Maizirwan Mel; Emirul Adzhar Yahya; and Mohd Rushdi Abu Bakar

    2011-01-01

    Spray drying is the most widely used industrial process involving particle formation and drying. It is highly suited for the continuous production of dry solids in either powder, granulate or agglomerate form from liquid feed-stocks as solutions, emulsions and pump able suspensions. Therefore, spray drying is an ideal process where the end-product must comply with precise quality standards regarding particle size distribution, residual moisture content, bulk density, and particle shape. In th...

  18. A packing computational method relating fractal particle size distribution and void fraction in granular media

    OpenAIRE

    García-Gutiérrez Baez, Carlos; Martin Martin, Miguel Angel; Muñoz Ortega, Francisco Javier; Reyes Castro, Miguel E.; Taguas Coejo, Francisco Javier

    2014-01-01

    The study of granular systems is of great interest to many fields of science and technology. The packing of particles affects to the physical properties of the granular system. In particular, the crucial influence of particle size distribution (PSD) on the random packing structure increase the interest in relating both, either theoretically or by computational methods. A packing computational method is developed in order to estimate the void fraction corresponding to a fractal-like particle s...

  19. Macrophage Responses to Silica Nanoparticles are Highly Conserved Across Particle Sizes

    Energy Technology Data Exchange (ETDEWEB)

    Waters, Katrina M.; Masiello, Lisa M.; Zangar, Richard C.; Tarasevich, Barbara J.; Karin, Norman J.; Quesenberry, Ryan D.; Bandyopadhyay, Somnath; Teeguarden, Justin G.; Pounds, Joel G.; Thrall, Brian D.

    2009-02-03

    Concerns about the potential adverse health effects of engineered nanoparticles stems in part from the possibility that some materials display unique chemical and physical properties at nanoscales which could exacerbate their biological activity. However, studies that have assessed the effect of particle size across a comprehensive set of biological responses have not been reported. Using a macrophage cell model, we demonstrate that the ability of unopsonized amorphous silica particles to stimulate inflammatory protein secretion and induce macrophage cytotoxicity scales closely with the total administered particle surface area across a wide range of particle diameters (7-500 nm). Whole genome microarray analysis of the early gene expression changes induced by 10 nm and 500 nm particles showed that the magnitude of change for the majority of genes affected correlated more tightly with particle surface area than either particle mass or number. Gene expression changes that were particle size-specific were also identified. However, the overall biological processes represented by all gene expression changes were nearly identical, irrespective of particle diameter. Direct comparison of the cell processes represented in the 10 nm and 500 nm particle gene sets using gene set enrichment analysis revealed that among 1009 total biological processes, none were statistically enriched in one particle size group over the other. The key mechanisms involved in silica nanoparticle-mediated gene regulation and cytotoxicity have yet to be established. However, our results suggest that on an equivalent nominal surface area basis, common biological modes of action are expected for nano- and supranano-sized silica particles.

  20. Effects of particle size distribution on some physical, chemical and functional properties of unripe banana flour.

    Science.gov (United States)

    Savlak, Nazlı; Türker, Burcu; Yeşilkanat, Nazlıcan

    2016-12-15

    The objective of this study was to examine the effect of particle size distribution on physical, chemical and functional properties of unripe banana flour for the first time. A pure triploid (AAA group) of Musa acuminata subgroup Cavendish (°Brix;0.2, pH;4.73, titratable acidity; 0.56g/100g malic acid, total solids; 27.42%) which was supplied from Gazipaşa, Antalya, Turkey from October 2014 to October 2015 was used. Size fractions of <212, 212-315, 316-500 and 501-700μm were characterized for their physical, functional and antioxidant properties. Particle size significantly effected color, water absorbtion index and wettability. L(∗) value decreased, a(∗) and b(∗) values decreased by increasing particle size (r(2)=-0.94, r(2)=0.72, r(2)=0.73 respectively). Particles under 212μm had the lowest rate of wettability (83.40s). A negative correlation between particle size and wettability (r(2)=-0.75) and positive correlation between particle size and water absorption index (r(2)=0.94) was observed. PMID:27451170

  1. 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