WorldWideScience

Sample records for size fractionated concentrations

  1. Size fractionation of waste-to-energy boiler ash enables separation of a coarse fraction with low dioxin concentrations

    DEFF Research Database (Denmark)

    Weidemann, E.; Allegrini, Elisa; Astrup, Thomas Fruergaard

    2016-01-01

    Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) formed in modern Waste-to-Energy plants are primarily found in the generated ashes and air pollution control residues, which are usually disposed of as hazardous waste. The objective of this study was to explore the occurrence of PCDD....../F in different grain size fractions in the boiler ash, i.e. ash originating from the convection pass of the boiler. If a correlation between particle size and dioxin concentrations could be found, size fractionation of the ashes could reduce the total amount of hazardous waste. Boiler ash samples from ten...... sections of a boiler's convective part were collected over three sampling days, sieved into three different size fractions - 0.355. mm - and analysed for PCDD/F. The coarse fraction (>0.355. mm) in the first sections of the horizontal convection pass appeared to be of low toxicity with respect to dioxin...

  2. Size fractionation of waste-to-energy boiler ash enables separation of a coarse fraction with low dioxin concentrations.

    Science.gov (United States)

    Weidemann, E; Allegrini, E; Fruergaard Astrup, T; Hulgaard, T; Riber, C; Jansson, S

    2016-03-01

    Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) formed in modern Waste-to-Energy plants are primarily found in the generated ashes and air pollution control residues, which are usually disposed of as hazardous waste. The objective of this study was to explore the occurrence of PCDD/F in different grain size fractions in the boiler ash, i.e. ash originating from the convection pass of the boiler. If a correlation between particle size and dioxin concentrations could be found, size fractionation of the ashes could reduce the total amount of hazardous waste. Boiler ash samples from ten sections of a boiler's convective part were collected over three sampling days, sieved into three different size fractions - 0.355 mm - and analysed for PCDD/F. The coarse fraction (>0.355 mm) in the first sections of the horizontal convection pass appeared to be of low toxicity with respect to dioxin content. While the total mass of the coarse fraction in this boiler was relatively small, sieving could reduce the amount of ash containing toxic PCDD/F by around 0.5 kg per tonne input waste or around 15% of the collected boiler ash from the convection pass. The mid-size fraction in this study covered a wide size range (0.09-0.355 mm) and possibly a low toxicity fraction could be identified by splitting this fraction into more narrow size ranges. The ashes exhibited uniform PCDD/F homologue patterns which suggests a stable and continuous generation of PCDD/F. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Improvement of Gold Leaching from a Refractory Gold Concentrate Calcine by Separate Pretreatment of Coarse and Fine Size Fractions

    Directory of Open Access Journals (Sweden)

    Qian Li

    2017-05-01

    Full Text Available A total gold extraction of 70.2% could only be reached via direct cyanidation from a refractory As-, S- and C-bearing gold concentrate calcine, and the gold extraction varied noticeably with different size fractions. The reasons for unsatisfactory gold extraction from the calcine were studied through analyses of chemical composition, chemical phase and SEM-EDS of different sizes of particles. It was found that a significant segregation of compositions occurred during the grinding of gold ore before flotation. As a result, for the calcine obtained after oxidative roasting, the encapsulation of gold by iron oxides was easily engendered in finer particles, whilst in coarser particles the gold encapsulation by silicates was inclined to occur likely due to melted silicates blocking the porosity of particles. The improvement of gold leaching from different size fractions was further investigated through pretreatments with alkali washing, acid pickling or sulfuric acid curing-water leaching. Finally, a novel process was recommended and the total gold extraction from the calcine could be increased substantially to 93.6% by the purposeful pretreatment with alkali washing for the relatively coarse size fraction (+37 μm and sulfuric acid curing–water leaching for the fine size fraction (−37 μm.

  4. Determination of concentration levels of arsenic, gold and antimony in particle-size fractions of gold ore using Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Nyarku, M.

    2009-02-01

    Instrumental Neutron Activation Analysis (INAA) has been used to quantify the concentrations of arsenic, gold and antimony in particle-size fractions of a gold ore. The ore, which was taken from the Ahafo project site of Newmont Ghana Gold Ltd, was first fractionated into fourteen (14) particle-size fractions using state-of-the-art analytical sieve machine. The minimum sieve mesh size used was 36 microns and grains >2000 microns were not considered for analysis. Results of the sieving were analysed with easysieve software. The < 36 microns sub fraction was found to be the optimum, hosting bulk of all three elements. For arsenic, the element was found to be highly concentrated in < 36 to +100 microns size fractions and erratically distributed from +150 microns fraction and above. For gold, in exception of the sub fraction <36 which had exceptionally high concentration, the element is distributed in all the size fractions but slightly 'plays out' in the +150 to +400 microns fractions. Antimony occurrence in the sample was relatively high in <36 microns size fraction followed by 600 - 800, 800 - 1000, 400 - 600 and 36 - 40 microns size fractions in that order. Gold content in the sample was far higher than that of arsenic and antimony. Gold concentration in the composite sample was in the range 564 - 8420 ppm. Arsenic levels were higher as compared to antimony. The range of arsenic concentration in the composite sample was 14.33 - 186.92 ppm. Antimony concentration was in the range 1.09 - 9.48 ppm. (au)

  5. Investigating concentration distributions of arsenic, gold and antimony in grain-size fractions of gold ore using instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Nyarku, M.; Nyarko, B.J.B.; Serfor-Armah, Y.; Osae, S.

    2010-01-01

    Instrumental neutron activation analysis (INAA) has been used to quantify concentrations of arsenic (As), gold (Au) and antimony (Sb) in grain-size fractions of a gold ore. The ore, which was taken from the Ahafo project site of Newmont Ghana Gold Ltd., was fractionated into 14 grain-size fractions using state-of-the-art analytical sieve machine. The minimum sieve mesh size used was 36 μm and grains >2000 μm were not considered for analysis. Result of the sieving was analysed with easysieve (registered) software. The<36 μm subfraction was found to be the optimum, hosting bulk of all three elements. Arsenic was found to be highly concentrated in<36-100 μm size fractions and erratically distributed in from 150 μm fraction and above. For gold, with the exception of the subfraction <36 μm which had exceptionally high concentration, the element was found to be approximately equally distributed in all the size fractions but slightly 'played out' in 150-400 μm size fractions. Antimony occurrence in the sample was relatively high in <36 μm size fraction followed by 600, 800, 400 and 36 μm size fractions in that order. Gold content in the sample was comparatively far greater than arsenic and antimony; this is indicative of level of gold mineralization in the concession where the sample ore was taken. The concentration of gold in the composite sample was in the range 564-8420 ppm as compared to 14.33-186.92 ppm for arsenic and 1.09-9.48 ppm for antimony. Elemental concentrations were correlated with each other and with grain-size fractions and the relationships between these descriptive parameters were established.

  6. Professional ski waxers' exposure to PFAS and aerosol concentrations in gas phase and different particle size fractions.

    Science.gov (United States)

    Nilsson, Helena; Kärrman, Anna; Rotander, Anna; van Bavel, Bert; Lindström, Gunilla; Westberg, Håkan

    2013-04-01

    Previous reports show that professional ski waxers have elevated blood levels of perfluorinated substances (PFAS) such as perfluorooctanoate (PFOA) and are exposed to very high concentrations of PFAS in air during ski waxing. Aerosol exposure increases the risk of cardiovascular disease, and PFOA is a potential hormonal disruptor and carcinogen, and can affect the fatty acid metabolism. Animal studies have shown that 8:2 FTOH can undergo biotransformation to PFOA. For the first time, this study presents an occupational scenario of professional ski waxers who are exposed to extremely high dust levels as well as per- and polyfluorinated compounds. Personal and fixed measurements of total aerosol, inhalable and respirable fractions were performed during World Cup events 2007-2010. The occupational exposure limit (OEL) is exceeded in 37% of the personal measurements with concentrations up to 15 mg m(-3) in air. There are differences between personal and area total aerosol concentrations with levels from personal measurements twice as high as those from the area measurements. The personal levels for FTOH ranged up to 996 μg m(-3) (mean = 114 μg m(-3)) and for PFOA up to 4.89 μg m(-3) (mean = 0.53 μg m(-3)) in ENV+ sorbent samples as compared to the general exposure levels from air reaching only low ng m(-3) (PFAS is not in compliance with the occupational exposure standards and by far exceed the general populations' exposure. Preventive measures must be taken to minimize the exposure in this occupational group.

  7. Evaluation and modelling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki - Part I: Modelling results within the LIPIKA project

    Science.gov (United States)

    Pohjola, M. A.; Pirjola, L.; Karppinen, A.; Härkönen, J.; Korhonen, H.; Hussein, T.; Ketzel, M.; Kukkonen, J.

    2007-08-01

    A field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17-20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm-10 μm (aerodynamic diameter) by the Electrical Low Pressure Impactor (ELPI) and in the size range of 3-50 nm (mobility diameter) by Scanning Mobility Particle Sizer (SMPS), total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC), temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. For model comparison purposes, one of the cases was additionally computed using the aerosol process model UHMA, combined with the CAR-FMI model. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes). We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible on this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of condensable organic

  8. Evaluation and modelling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki ─ Part I: Modelling results within the LIPIKA project

    Directory of Open Access Journals (Sweden)

    M. Ketzel

    2007-08-01

    Full Text Available A field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17–20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm–10 μm (aerodynamic diameter by the Electrical Low Pressure Impactor (ELPI and in the size range of 3–50 nm (mobility diameter by Scanning Mobility Particle Sizer (SMPS, total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC, temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. For model comparison purposes, one of the cases was additionally computed using the aerosol process model UHMA, combined with the CAR-FMI model. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes. We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible on this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of

  9. Suspended-sediment concentrations, loads, total suspended solids, turbidity, and particle-size fractions for selected rivers in Minnesota, 2007 through 2011

    Science.gov (United States)

    Ellison, Christopher A.; Savage, Brett E.; Johnson, Gregory D.

    2014-01-01

    Sediment-laden rivers and streams pose substantial environmental and economic challenges. Excessive sediment transport in rivers causes problems for flood control, soil conservation, irrigation, aquatic health, and navigation, and transports harmful contaminants like organic chemicals and eutrophication-causing nutrients. In Minnesota, more than 5,800 miles of streams are identified as impaired by the Minnesota Pollution Control Agency (MPCA) due to elevated levels of suspended sediment. The U.S. Geological Survey, in cooperation with the MPCA, established a sediment monitoring network in 2007 and began systematic sampling of suspended-sediment concentrations (SSC), total suspended solids (TSS), and turbidity in rivers across Minnesota to improve the understanding of fluvial sediment transport relations. Suspended-sediment samples collected from 14 sites from 2007 through 2011 indicated that the Zumbro River at Kellogg in the driftless region of southeast Minnesota had the highest mean SSC of 226 milligrams per liter (mg/L) followed by the Minnesota River at Mankato with a mean SSC of 193 mg/L. During the 2011 spring runoff, the single highest SSC of 1,250 mg/L was measured at the Zumbro River. The lowest mean SSC of 21 mg/L was measured at Rice Creek in the northern Minneapolis- St. Paul metropolitan area. Total suspended solids (TSS) have been used as a measure of fluvial sediment by the MPCA since the early 1970s; however, TSS concentrations have been determined to underrepresent the amount of suspended sediment. Because of this, the MPCA was interested in quantifying the differences between SSC and TSS in different parts of the State. Comparisons between concurrently sampled SSC and TSS indicated significant differences at every site, with SSC on average two times larger than TSS concentrations. The largest percent difference between SSC and TSS was measured at the South Branch Buffalo River at Sabin, and the smallest difference was observed at the Des Moines

  10. Heavy metals in the finest size fractions of road-deposited sediments.

    Science.gov (United States)

    Lanzerstorfer, Christof

    2018-08-01

    The concentration of heavy metals in urban road-deposited sediments (RDS) can be used as an indicator for environmental pollution. Thus, their occurrence has been studied in whole road dust samples as well as in size fractions obtained by sieving. Because of the limitations of size separation by sieving little information is available about heavy metal concentrations in the road dust size fractions heavy metals concentrations and size distribution. According to the Geoaccumulation Index the pollution of the road dust samples deceased in the following order: Sb » As > Cu ≈ Zn > Cr > Cd ≈ Pb ≈ Mn > Ni > Co ≈ V. For all heavy metals the concentration was higher in the fine size fractions compared to the coarse size fractions, while the concentration of Sr was size-independent. The enrichment of the heavy metals in the finest size fraction compared to the whole RDS  Sb > (Cu) ≈ Zn ≈ Pb > As ≈ V » Mn. The approximation of the size dependence of the concentration as a function of the particle size by power functions worked very well. The correlation between particle size and concentration was high for all heavy metals. The increased heavy metals concentrations in the finest size fractions should be considered in the evaluation of the contribution of road dust re-suspension to the heavy metal contamination of atmospheric dust. Thereby, power functions can be used to describe the size dependence of the concentration. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Table-sized matrix model in fractional learning

    Science.gov (United States)

    Soebagyo, J.; Wahyudin; Mulyaning, E. C.

    2018-05-01

    This article provides an explanation of the fractional learning model i.e. a Table-Sized Matrix model in which fractional representation and its operations are symbolized by the matrix. The Table-Sized Matrix are employed to develop problem solving capabilities as well as the area model. The Table-Sized Matrix model referred to in this article is used to develop an understanding of the fractional concept to elementary school students which can then be generalized into procedural fluency (algorithm) in solving the fractional problem and its operation.

  12. Metals in particle-size fractions of the soils of five European cities

    International Nuclear Information System (INIS)

    Ajmone-Marsan, F.; Biasioli, M.; Kralj, T.; Grcman, H.; Davidson, C.M.; Hursthouse, A.S.; Madrid, L.; Rodrigues, S.

    2008-01-01

    Soils from Aveiro, Glasgow, Ljubljana, Sevilla and Torino have been investigated in view of their potential for translocation of potentially toxic elements (PTE) to the atmosphere. Soils were partitioned into five size fractions and Cr, Cu, Ni, Pb and Zn were measured in the fractions and the whole soil. All PTE concentrated in the <10 μm fraction. Cr and Ni concentrated also in the coarse fraction, indicating a lithogenic contribution. An accumulation factor (AF) was calculated for the <2 and <10 μm fraction. The AF values indicate that the accumulation in the finer fractions is higher where the overall contamination is lower. AF for Cr and Ni are particularly low in Glasgow and Torino. An inverse relationship was found between the AF of some metals and the percentage of <10 μm particles that could be of use in risk assessment or remediation practices. - Metals in size fractions of urban soils

  13. 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.

  14. Fission-nuclide concentrations of ambient aerosol separated by size

    International Nuclear Information System (INIS)

    Csepregi, T.; Kovacs, L.; Maschek, I.; Szterjopulos, K.

    1984-01-01

    Examinations were carried on the radionuclides in aerosol deposited on filters of an air-conditioning plant with high air flow rate. For nuclide concentration of ambient air qualitative and quantitative analyses were made by gamma spectrometry. Methods have been developed for sample preparation, size fractionation by sedimentation technique and measurement of air flow. The collected aerosol particles was separated into five size fractions from 1 to 5 μm and the aerosol fractions were analysed. The mass/size distribution of the particles processed by sedimentation has been compared with that of the ambient aerosol separated by a slot impactor Hungarian type. Because the aggregation caused by the resuspensationtechnique would be assumed, electronmicrophotos were made on processed and unprocessed aerosols. On the basis of them the particle aggregation may be negligible. Otherwise, the derivation of concentration needs to know the exact air volume. For this aim the technical parameters of the aerodynamic system have also been measured in two different ways. The paper reports on the size dependence of fission products originating from the present global late fallout for a two years monitoring period. The results are compared with the daily beta activity concentration of aerosol samples taken by an other sampling unit. (Author)

  15. Uranium release from different size fractions of sediments in Hanford 300 area, Washington, USA

    International Nuclear Information System (INIS)

    Du Jiangkun; Bao Jianguo; Hu Qinhong; Ewing, Robert P.

    2012-01-01

    Stirred-flow cell tests were carried out to investigate uranium (U) release from different size fractions of sediments from the U.S. Department of Energy’s Hanford 300 Area in Washington, USA. Results show that the measured concentration of U release varies with different size fractions, with the fine-grained mass fractions (<75 μm, 75–500 μm, and 500–2000 μm) being the main U carriers. However, because the sediment is mainly composed of gravel (2000–8000 μm) materials, the gravel fraction is a non-negligible U pool. Our elution experiments give a value of 8.7% of the total U being in the gravel fraction, significantly reducing the current uncertainty in evaluating U inventory. A log–log plot of released U concentration vs. elution volume (i.e., elution time) shows a power-law relationship for all size fractions, with identical exponents for the three fine size fractions (−0.875). For the <2000 μm mass fraction, comparing our eluted U values with reported total U concentrations, we estimate that a lower bound value 8.6% of the total uranium is labile. This compares well with the previously published value of 11.8% labile U after extraction with a dilute extractant for three weeks. - Highlights: ► Stirred-flow cells were used to study U release in Hanford 300 Area sediment. ► Fine-grained size fractions have higher U concentrations. ► U in coarse fraction is less studied, but its 8.7–9.3% of total U is non-negligible. ► A power-law relationship is observed between released U and elution volume. ► About 8.6% of U in the <2 mm sediment is labile.

  16. Size fractionation and characterization of natural aquatic colloids and nanoparticles

    International Nuclear Information System (INIS)

    Baalousha, M.; Lead, J.R.

    2007-01-01

    Atomic force microscopy (AFM) was used to image and quantify natural nanoparticles (prefiltered < 25 nm) from three different freshwater sites (Vale Lake, Bailey Brook and Tern Rivers). Four fractions were analysed by AFM; the prefiltered fraction (< 25 nm) and three fractions collected after separation of this prefiltered sample by flow field-flow fractionation (FlFFF) which corresponds to material which has size ranges of < 4.2 nm, 4.2-15.8 nm and 15.8-32.4 nm, as determined by FlFFF theory. The large majority of materials in all samples appeared as < 3 nm nanoparticles, nearly spherical and rich in chromophores active at 254 nm UV, which thus correspond to natural organic matter. However, nanoparticles were also imaged up to slightly more than 25 nm in size, indicating a slight disagreement in sizing between filtration and FlFFF. In addition, some particles in certain fractions were found to be covered with a thin film of less than 0.5-1.0 nm. Substantial differences between sites were observed

  17. Density fractions versus size separates: does physical fractionation isolate functional soil compartments?

    Directory of Open Access Journals (Sweden)

    C. Moni

    2012-12-01

    Full Text Available Physical fractionation is a widely used methodology to study soil organic matter (SOM dynamics, but concerns have been raised that the available fractionation methods do not well describe functional SOM pools. In this study we explore whether physical fractionation techniques isolate soil compartments in a meaningful and functionally relevant way for the investigation of litter-derived nitrogen dynamics at the decadal timescale. We do so by performing aggregate density fractionation (ADF and particle size-density fractionation (PSDF on mineral soil samples from two European beech forests a decade after application of 15N labelled litter.

    Both density and size-based fractionation methods suggested that litter-derived nitrogen became increasingly associated with the mineral phase as decomposition progressed, within aggregates and onto mineral surfaces. However, scientists investigating specific aspects of litter-derived nitrogen dynamics are pointed towards ADF when adsorption and aggregation processes are of interest, whereas PSDF is the superior tool to research the fate of particulate organic matter (POM.

    Some methodological caveats were observed mainly for the PSDF procedure, the most important one being that fine fractions isolated after sonication can not be linked to any defined decomposition pathway or protective mechanism. This also implies that historical assumptions about the "adsorbed" state of carbon associated with fine fractions need to be re-evaluated. Finally, this work demonstrates that establishing a comprehensive picture of whole soil OM dynamics requires a combination of both methodologies and we offer a suggestion for an efficient combination of the density and size-based approaches.

  18. DISTRIBUTION OF METALS IN PARTICLE SIZE FRACTIONS IN SOILS OF TWO FORESTED CATENAS (SMOLENSK-MOSCOW UPLAND

    Directory of Open Access Journals (Sweden)

    Olga Samonova

    2013-01-01

    Full Text Available The concentrations and distribution of Fe, Ti, Zr, Mn, Cu. Ni, Co, Cr, Pb, and Zn associated with various particle size fractions have been analyzed in soils of two forested catenas located in the middle Protva River basin on the Smolensk-Moscow Upland. The results showed that concentration of metals in a particular size fraction was defined by a complex of factors: element chemical properties, soil type, genesis of a soil horizon, and position in the catena. A clearly defined relationship between the fraction size and metal concentrations was found for Ti and Zr. The highest levels of Ti were found in coarse and medium silt, while Zr had its highest values only in coarse silt and, in some cases, in fine sand. Such metals as Fe, Mn, Co, Cu and Pb had high concentrations in sand, fine silt, and clay fractions depending on a soil type and a genetic horizon. The maximum load of Cr, Zn, and Ni (in the majority of cases was found in clay fraction. The minimum loads of Fe, Mn, Co, Cu, and Ni were found in the coarse silt fraction. Variation in concentrations of heavy metals differed depending on particle size. For most metals, the variations were decreasing from coarser to finer fractions.Key words: soils, heavy metals, grain-size fractionation, vertical and lateral distribution patterns

  19. A procedure for partitioning bulk sediments into distinct grain-size fractions for geochemical analysis

    Science.gov (United States)

    Barbanti, A.; Bothner, Michael H.

    1993-01-01

    A method to separate sediments into discrete size fractions for geochemical analysis has been tested. The procedures were chosen to minimize the destruction or formation of aggregates and involved gentle sieving and settling of wet samples. Freeze-drying and sonication pretreatments, known to influence aggregates, were used for comparison. Freeze-drying was found to increase the silt/clay ratio by an average of 180 percent compared to analysis of a wet sample that had been wet sieved only. Sonication of a wet sample decreased the silt/clay ratio by 51 percent. The concentrations of metals and organic carbon in the separated fractions changed depending on the pretreatment procedures in a manner consistent with the hypothesis that aggregates consist of fine-grained organic- and metal-rich particles. The coarse silt fraction of a freeze-dried sample contained 20–44 percent higher concentrations of Zn, Cu, and organic carbon than the coarse silt fraction of the wet sample. Sonication resulted in concentrations of these analytes that were 18–33 percent lower in the coarse silt fraction than found in the wet sample. Sonication increased the concentration of lead in the clay fraction by an average of 40 percent compared to an unsonicated sample. Understanding the magnitude of change caused by different analysis protocols is an aid in designing future studies that seek to interpret the spatial distribution of contaminated sediments and their transport mechanisms.

  20. X-ray diffraction and thermal analysis of kaolins particle size fractions

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    Patricia dos Santos

    2013-09-01

    Full Text Available Kaolins are common geological materials and have high concentrations of kaolinite as well as the clay fraction of tropical and subtropical soils of Brazil. The characterization of kaolin is a proxy of assessing the contribution of kaolinite to important soil chemical and mineralogical attributes. This study evaluated four kaolins (commercial kaolin A (CCA, commercial kaolin B (CCB, pink sandy kaolin A (CRA and green sandy kaolin A (CVA in the original form and after particle size separation into: sand (200-53 mm, coarse silt (53-20 m, fine silt (20-2 m, large clay (2-1m, medium clay (1-0.5 m and fine clay (<0.5m fractions. The minerals were identified by X-ray diffraction (XRD and evaluated for crystallinity (kaolinite and halloysite through indexes Hughes and Brown, Amigó, Bramão and the dehydroxylation temperature. The physical fractionation was efficient to concentrate minerals in specific size fractions which were not identified in the original material. In CCA kaolin was concentrated one mineral which remains unidentified in fine fractions, in kaolin CRA, zircon was concentrated in the coarse silt and different silicates in the fine fractions, in kaolin CCB were concentrated kaolinite and a silicate in the medium and coarse clay fractions. The estimate by X-ray diffraction overestimated the amount of kaolinite and halloysite underestimated when compared to quantification by thermal gravimetric analysis The crystallinity index exhibit different behaviors depending on the mineralogy of each material, thus the correlation between the crystallinity of kaolinite and / or halloysite and other variables, may be compromised, especially in materials with distinct geological origins.

  1. Mineralogical variation in the size fractions of a Ranong kaolin, southern Thailand

    Science.gov (United States)

    Pisutha-Arnond, Visut; Phuvichit, Suraphol; Leepowpanth, Quanchai

    A representative crude Ranong kaolin from the Thungkla-Ranong mine was separated into > 2 mm (granule), 2-1 mm (very coarse sand), 1-0.5 mm (coarse sand), 0.5-0.25 mm (medium sand), 0.25-0.125 mm (fine sand), 0.125-0.062 mm (very fine sand) and 62-28, 28-14, 17-7, 7-4, 4-2, 2-1 and dispersive X-ray spectrometer (EDX). Kaolin group minerals were differentiated by using XRD in combination with various chemical and heat treatments together with TEM, SEM and DTA. The Ranong kaolin consists predominantly of tubular halloysite, poorly crystallized kaolinite and quartz with minor amounts of mica and K-feldspars. Other trace constituents include gibbsite, tourmaline, zircon and colored impurities (i.e. extractable iron hydroxide coating on clay mineral surface). The kaolin minerals are found in all size fractions by which their contents and halloysite/kaolinite ratios increase as the particle sizes become finer. Quartz and mica are also detected in almost all size fractions. They are, however, more abundant with coarsening particle size. Gibbsite, K-feldspar and tourmaline are mainly concentrated in the fine sand to silt size fractions. Crystallinity of kaolin minerals as measured by XRD varied moderately with size. Relatively pure kaolin minerals, predominantly halloysite and kaolinite, can be obtained in the particle size below 1 or 2 μm.

  2. Collection of size fractionated particulate matter sample for neutron activation analysis in Japan

    International Nuclear Information System (INIS)

    Otoshi, Tsunehiko; Nakamatsu, Hiroaki; Oura, Yasuji; Ebihara, Mitsuru

    2004-01-01

    According to the decision of the 2001 Workshop on Utilization of Research Reactor (Neutron Activation Analysis (NAA) Section), size fractionated particulate matter collection for NAA was started from 2002 at two sites in Japan. The two monitoring sites, ''Tokyo'' and ''Sakata'', were classified into ''urban'' and ''rural''. In each site, two size fractions, namely PM 2-10 '' and PM 2 '' particles (aerodynamic particle size between 2 to 10 micrometer and less than 2 micrometer, respectively) were collected every month on polycarbonate membrane filters. Average concentrations of PM 10 (sum of PM 2-10 and PM 2 samples) during the common sampling period of August to November 2002 in each site were 0.031mg/m 3 in Tokyo, and 0.022mg/m 3 in Sakata. (author)

  3. The role of particle-size soil fractions in the adsorption of heavy metals

    Science.gov (United States)

    Mandzhieva, Saglara; Minkina, Tatiana; Pinsky, David; Batukaev, Abdulmalik; Kalinitchenko, Valeriy; Sushkova, Svetlana; Chaplygin, Viktor; Dikaev, Zaurbek; Startsev, Viktor; Bakoev, Serojdin

    2014-05-01

    Ion-exchange adsorption phenomena are important in the immobilization of heavy metals (HMs) by soils. Numerous works are devoted to the study of this problem. However, the interaction features of different particle-size soil fractions and their role in the immobilization of HMs studied insufficiently. Therefore, the assessment of the effect of the particle-size distribution on the adsorption properties of soils is a vital task. The parameters of Cu2+, Pb2+ and Zn2+ adsorption by chernozems of the south of Russia and their particle-size fractions were studied. In the particle-size fractions separated from the soils, the concentrations of Cu2+, Pb2+, and Zn2 decreased with the decreasing particle size. The parameters of the adsorption values of k (the constant of the affinity)and Cmax.(the maximum adsorption of the HMs) characterizing the adsorption of HMs by the southern chernozem and its particle-size fractions formed the following sequence: silt > clay > entire soil. The adsorption capacity of chernozems for Cu2+, Pb2+, and Zn2+ depending on the particle-size distribution decreased in the following sequence: clay loamy ordinary chernozem clay loamy southern chernozem> loamy southern chernozem> loamy sandy southern chernozem. According to the parameters of the adsorption by the different particle-size fractions, the heavy metal cations form a sequence analogous to that obtained for the entire soils: Cu2+ ≥ Pb2+ > Zn2+. The parameters of the heavy metal adsorption by similar particle-size fractions separated from different soils decreased in the following order: clay loamy chernozem> loamy chernozem> loamy sandy chernozem. The analysis of the changes in the parameters of the Cu2+, Pb2+, and Zn2+ adsorption by the studied soils and their particle-size fractions showed that the extensive adsorption characteristic - the maximum adsorption (Cmax.) - is a less sensitive parameter characterizing the adsorption capacity of the soils than the intensive characteristic of

  4. Compact and tunable size-based dielectrophoretic flow fractionation

    International Nuclear Information System (INIS)

    Chuang, Han-Sheng; Chung, Tien-Yu; Li, Yun

    2014-01-01

    A compact and tunable size-based flow fractionation microchip using negative dielectrophoresis (DEP) is presented in this paper. In the microchip, a sample containing a mixture of particles is hydrodynamically focused in a contraction section and then sorted by size after flowing over planar interdigitated electrodes. The electrodes and flow chamber were aligned at an angle of 45° to produce effective sorting. 1, 2.5 and 4.8 µm polystyrene (PS) particles were successfully separated into three distinct streams in a short distance (1 mm) and collected in different outlet channels. The sorting was subjected to flow rates and electric potential. The experimental sorting efficiencies of 1, 2.5 and 4.8 µm particles reached 97.2%, 79.6% and 99.8%, respectively. With the same device, lipid vesicle sorting was demonstrated. 86.9% of vesicles larger than 10 µm were effectively extracted from the sample stream. Likewise, sorting of other biological particles can be achieved in the same fashion. (paper)

  5. Fractional kalman filter to estimate the concentration of air pollution

    Science.gov (United States)

    Vita Oktaviana, Yessy; Apriliani, Erna; Khusnul Arif, Didik

    2018-04-01

    Air pollution problem gives important effect in quality environment and quality of human’s life. Air pollution can be caused by nature sources or human activities. Pollutant for example Ozone, a harmful gas formed by NOx and volatile organic compounds (VOCs) emitted from various sources. The air pollution problem can be modeled by TAPM-CTM (The Air Pollution Model with Chemical Transport Model). The model shows concentration of pollutant in the air. Therefore, it is important to estimate concentration of air pollutant. Estimation method can be used for forecast pollutant concentration in future and keep stability of air quality. In this research, an algorithm is developed, based on Fractional Kalman Filter to solve the model of air pollution’s problem. The model will be discretized first and then it will be estimated by the method. The result shows that estimation of Fractional Kalman Filter has better accuracy than estimation of Kalman Filter. The accuracy was tested by applying RMSE (Root Mean Square Error).

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

    Science.gov (United States)

    Sunnu, A. K.

    2010-12-01

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

  7. Relation between PAH and black carbon contents in size fractions of Norwegian harbor sediments

    International Nuclear Information System (INIS)

    Oen, Amy M.P.; Cornelissen, Gerard; Breedveld, Gijs D.

    2006-01-01

    Distributions of total organic carbon (TOC), black carbon (BC), and polycyclic aromatic hydrocarbons (PAH) were investigated in different particle size fractions for four Norwegian harbor sediments. The total PAH (16-EPA) concentrations ranged from 2 to 113 mg/kg dry weight with the greatest fraction of PAH mass in the sand fraction for three of the four sediments. TOC contents ranged from 0.84% to 14.2% and BC contents from 0.085% to 1.7%. This corresponds to organic carbon (OC = TOC - BC) contents in the range of 0.81-14% and BC:TOC ratios of 1.3-18.1%. PAH isomer ratios suggested that the PAH in all four sediments were of pyrogenic origin. Furthermore, stronger correlations between PAH versus BC (r 2 = 0.85) than versus OC (r 2 = 0.15) were found. For all size fractions and bulk sediments, the PAH-to-BC ratios for the total PAHs were on average 6 ± 3 mg PAH/g BC. These results suggest that PAH distributions were dominated by the presence of BC, rather than OC. As sorption to BC is much stronger than sorption to OC, this may result in significantly lower dissolved concentrations of PAH than expected on the basis of organic carbon partitioning alone. - PAH contents correlated better with black carbon than organic carbon for four Norwegian harbor sediments

  8. Separation of copper flotation concentrates into density fractions by means of polytungstate aqueous solution

    Directory of Open Access Journals (Sweden)

    Luszczkiewicz Andrzej

    2016-01-01

    Full Text Available Industrial and laboratory flotation copper concentrates were subjected to separation into density fractions by means of heavy liquids in the form of sodium polytungstate aqueous solutions. For two samples, three densities factions were created, however in different density ranges. The density fractions were analyzed to establish the content of copper, lead, silver and organic carbon. The size of particles in both samples was similar (90-95% −0.071 mm. It was found that the lightest density fractions −2.45 and −2.0 g/cm3 still contained sulfide minerals scattered in the organic carbon bearing particles. Removal of the lightest density fraction (−2.0 g/cm3 from the industrial concentrate samples led to considerable reduction of organic carbon (92% and increasing its quality from 13 to 28% Cu. The mineralogical analysis of the heavy liquid separation products showed that most sulfide minerals were evenly dissemination in the heaviest density fractions with the recovery of 95-98%. The lightest density fraction of −2.0 g/cm3, being the richest in organic carbon, contained approximately 3% of unliberated sulfide minerals.

  9. Diel feeding rhythm of copepod size-fractions from Coliumo Bay, Central Chile

    Directory of Open Access Journals (Sweden)

    Danilo Calliari

    2001-12-01

    Full Text Available The feeding behaviour of the size fractionated copepod assemblage was studied over a diel cycle in Coliumo Bay. In this shallow environment the photic layer reached the bottom and salinity, temperature, and food availability were fairly homogeneous throughout the water column. All four size-fractions (250-500 ?m, 500-1000 ?m, 1000-2000 ?m, >2000 ?m showed a period of high feeding activity during the night and low feeding activity during the day. The persistence of nocturnal feeding in the presence of high food concentration over the 24-h cycle is interpreted as a predator avoidance strategy: empty guts by day make copepods less conspicuous to their visual daytime predators.

  10. Concentration and fractionation of hydrophobic organic acid constituents from natural waters by liquid chromatography

    Science.gov (United States)

    Thurman, E.M.; Malcolm, R.L.

    1979-01-01

    A scheme is presented which used adsorption chromatography with pH gradient elution and size-exclusion chromatography to concentrate and separate hydrophobic organic acids from water. A review of chromatographic processes involved in the flow scheme is also presented. Organic analytes which appear in each aqueous fraction are quantified by dissolved organic carbon analysis. Hydrophobic organic acids in a water sample are concentrated on a porous acrylic resin. These acids usually constitute approximately 30-50 percent of the dissolved organic carbon in an unpolluted water sample and are eluted with an aqueous eluent (dilute base). The concentrate is then passed through a column of polyacryloylmorpholine gel, which separates the acids into high- and low-molecular-weight fractions. The high- and low-molecular-weight eluates are reconcentrated by adsorption chromatography, then are eluted with a pH gradient into strong acids (predominately carboxylic acids) and weak acids (predominately phenolic compounds). For standard compounds and samples of unpolluted waters, the scheme fractionates humic substances into strong and weak acid fractions that are separated from the low molecular weight acids. A new method utilizing conductivity is also presented to estimate the acidic components in the methanol fraction.

  11. Concentration and size distribution of particles in abstracted groundwater

    NARCIS (Netherlands)

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

    2010-01-01

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

  12. Dynamics of size-fractionated phytoplankton biomass in a monsoonal estuary: Patterns and drivers for seasonal and spatial variability

    Science.gov (United States)

    Rajaneesh, K. M.; Mitbavkar, Smita; Anil, Arga Chandrashekar

    2018-07-01

    Phytoplankton size-fractionated biomass is an important determinant of the type of food web functioning in aquatic ecosystems. Knowledge about the effect of seasonal salinity gradient on the size-fractionated biomass dynamics is still lacking, especially in tropical estuaries experiencing monsoon. The phytoplankton size-fractionated chlorophyll a biomass (>3 μm and 3 μm size-fraction was the major contributor to the total phytoplankton chlorophyll a biomass with the ephemeral dominance of biomass concentration of both size-fractions showed signs of recovery with increasing salinity downstream towards the end of the monsoon season. In contrast, the chlorophyll a biomass response was size-dependent during the non-monsoon seasons with the sporadic dominance (>50%) of biomass during high water temperature episodes from downstream to middle estuary during pre-monsoon and at low salinity and high nutrient conditions upstream during post-monsoon. These conditions also influenced the picophytoplankton community structure with picoeukaryotes dominating during the pre-monsoon, phycoerythrin containing Synechococcus during the monsoon and phycocyanin containing Synechococcus during the post-monsoon. This study highlights switching over of dominance in size-fractionated phytoplankton chlorophyll a biomass at intra, inter-seasonal and spatial scales which will likely govern the estuarine trophodynamics.

  13. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    Science.gov (United States)

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-06-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg-1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg-1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

  14. The role of soil's particle-size fractions in the adsorption of heavy metals

    Directory of Open Access Journals (Sweden)

    Saglara Mandzhieva

    2014-08-01

    Full Text Available The parameters of adsorption of Cu2+, Pb2+, and Zn2+ cations by southern chernozem and their particle-size fractions were studied. The adsorption of metals by soils and the strength of their fixation on the surface of soil particles under both mono- and poly-element contamination decreased with the decreasing proportion of fine fractions in the soil. The aim of this work was to study the effect of the particle-size distribution and the silt and physical clay fractions on the adsorption of copper, lead, and zinc by chernozems. The objects of study included the upper humus horizons of different southern chernozems of the Rostov oblast. To study the ion-exchange adsorption of the Cu2+, Pb2+, and Zn2+ cations, the soil in the natural ionic form was disaggregated using a pestle with a rubber head and sieved through a 1mm sieve. The soil samples were treated with solutions of Cu2+, Pb2+, and Zn2+ nitrates and acetates at the separate and simultaneous presence of heavy metals (HMs. In the solutions with the simultaneous presence of HMs, their molar concentrations were similar. The concentrations of the initial solutions varied in the range from 0.05 to 1 mM/l. The soil: solution ratio was 1:10. The contents of HMs in the filtrates were determined by atomic absorption spectrophotometry. The contents of adsorbed HM cations were calculated from the difference between the metal concentrations in the initial and equilibrium solutions. The increase in the degree of dispersion of the particle-size fractions in similar soils resulted not only in an increase in the content of adsorbed HMs but also in an enhancement of their fixation on the surface of the fine particles. Therefore, the adsorption capacity of the Lower Don soils for Cu2+, Pb2+, and Zn2+ decreased in the following sequence: clay loamy southern chernozem > loamy southern chernozem > loamy sandy southern chernozem. This was related to the qualitative differences in the mineralogy and chemistry of

  15. Transmission and fractionation of micro-sized particle suspensions

    NARCIS (Netherlands)

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

    2007-01-01

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

  16. Unattached fraction and the size distribution of the radon progeny in indoor air

    International Nuclear Information System (INIS)

    Yamasaki, K.; Shimo, M.

    1992-01-01

    The size-distribution of the aerosol-attached radon progeny and the unattached (cluster) fraction were measured by using a low pressure cascade impactor and a single wire screen in a building of the nuclear facility. The radon concentration at the condition of ventilation 'ON' was about 50 Bq m -3 , but it increased exponentially after ventilation 'OFF' and reached to the saturated concentration of about 600 Bq m -3 . At the condition of low aerosol concentration without additional aerosol, the activity median aerodynamic diameter, the geometric standard deviation and the unattached fraction were, respectively, 0.4 μm, 2.7-2.9 and 0.3-0.5. On the other hand, at the condition of high aerosol concentration with burning a mosquito coil, these were, 0.4 μm, 2.1 and 0.02-0.03. These yield 2.5 times higher radiation dose conversion factors at the low aerosol condition than the high aerosol condition. (author)

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

    Science.gov (United States)

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

    2010-02-01

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

  18. Dry fractionation for sustainable production of functional legume protein concentrates

    NARCIS (Netherlands)

    Schutyser, M.A.I.; Pelgrom, P.J.M.; Goot, van der A.J.; Boom, R.M.

    2015-01-01

    Plant proteins gain increasing interest as part of a sustainable diet. Because plant materials not only contain protein, they are generally isolated via an energy intensive wet fractionation. This review discusses dry fractionation as an alternative and more sustainable route for producing

  19. Functional groups and reactivity of size-fractionated Aldrich humic acid

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Tadao, E-mail: tanaka.tadao26@jaea.go.jp [Nuclear Safety Research Center, Japan Atomic Energy Agency, Shirakata 2-4, Tokai, Naka, Ibaraki, 319-1195 (Japan)

    2012-03-20

    The complexation affinity of the Aldrich Chemicals humic acid with {sup 60}Co was examined with respect to molecular size of humic acid. Correlations between the affinity and the structures of humic acid were studied. At low humic acid concentration range, {sup 60}Co was interacted with the humic acid of size fraction over 100k Da (HA(100<)). With increasing humic acid concentration, the {sup 60}Co was preferentially interacted with the 30k-100k Da of humic acid (HA(30-100)). Fractionated HA(100<) and HA(30-100) were characterized from their FTIR (Fourier Transform Infra-Red), {sup 13}C NMR spectral analyses and acid-base titration curves. The HA(10<) having aliphatic branched structure, smaller amount of COOH group and large proton exchangeable capacity, seem to show low covalent bonding nature and high ion exchangeability in the complexation. In addition, steric hindrance may affect on the complexation, by winding up like random coils from the branched structure. The HA(30-100) is dominated with the aromatic COOH group and OH group and it may preferentially coordinate to {sup 60}Co by covalent binding. These presumptions were supported by XPS analysis, in which the biding energy of cobalt-humates was discussed.

  20. Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives.

    Science.gov (United States)

    Contado, Catia; Ravani, Laura; Passarella, Martina

    2013-07-25

    Four types of SiO2, available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w(-1)) a nearly silica-free instant barley coffee powder with a known SiO2 sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO2 particles and verify the new particle size distribution. The SiO2 content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w(-1)). The protocol to isolate the silica particles was so applied to the most SiO2-rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Characterization of the Particle Size Fraction associated with Heavy Metals in Suspended Sediments of the Yellow River

    Directory of Open Access Journals (Sweden)

    Qingzhen Yao

    2015-06-01

    Full Text Available Variations in the concentrations of particulate heavy metals and fluxes into the sea in the Yellow River were examined based on observational and measured data from January 2009 to December 2010. A custom-built water elutriation apparatus was used to separate suspended sediments into five size fractions. Clay and very fine silt is the dominant fraction in most of the suspended sediments, accounting for >40% of the samples. Cu, Pb, Zn, Cr, Fe and Mn are slightly affected by anthropogenic activities, while Cd is moderate affected. The concentrations of heavy metals increased with decrease in particle size. For suspended sediments in the Yellow River, on average 78%–82% of the total heavy metal loading accumulated in the <16 μm fraction. About 43% and 53% of heavy metal in 2009 and 2010 respectively, were readily transported to the Bohai Sea with “truly suspended” particles, which have potentially harmful effects on marine organisms.

  2. Particle size fractionation of paralytic shellfish toxins (PSTs): seasonal distribution and bacterial production in the St Lawrence estuary, Canada.

    Science.gov (United States)

    Michaud, S; Levasseur, M; Doucette, G; Cantin, G

    2002-10-01

    We determined the seasonal distribution of paralytic shellfish toxins (PSTs) and PST producing bacteria in > 15, 5-15, and 0.22-5 microm size fractions in the St Lawrence. We also measured PSTs in a local population of Mytilus edulis. PST concentrations were determined in each size fraction and in laboratory incubations of sub-samples by high performance liquid chromatography (HPLC), including the rigorous elimination of suspected toxin 'imposter' peaks. Mussel toxin levels were determined by mouse bioassay and HPLC. PSTs were detected in all size fractions during the summer sampling season, with 47% of the water column toxin levels associated with particles smaller than Alexandrium tamarense ( 15 microm size fraction, we estimated that as much as 92% of PSTs could be associated with particles other than A. tamarense. Our results stress the importance of taking into account the potential presence of PSTs in size fractions other than that containing the known algal producer when attempting to model shellfish intoxication, especially during years of low cell abundance. Finally, our HPLC results confirmed the presence of bacteria capable of autonomous PST production in the St Lawrence as well as demonstrating their regular presence and apparent diversity in the plankton. Copyright 2002 Elsevier Science Ltd.

  3. Oxidative potential of size-fractionated atmospheric aerosol in urban and rural sites across Europe.

    Science.gov (United States)

    Shafer, Martin M; Hemming, Jocelyn D C; Antkiewicz, Dagmara S; Schauer, James J

    2016-07-18

    In this study we applied several assays, an in vitro rat alveolar macrophage model, a chemical ROS probe (DTT, dithiothreitol), and cytokine induction (TNFα) to examine relationships between PM-induced generation of reactive oxygen species (ROS) and PM composition, using a unique set of size-resolved PM samples obtained from urban and rural environments across Europe. From April-July 2012, we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities and from three rural sites spanning the continent. A Hi-Vol sampler was used to collect PM in three size classes (PM>7, PM7-3, PM3) and PM was characterized for total elements, and oxidative activity quantified in unfiltered and filtered PM extracts. We measured a remarkable uniformity in air concentrations of ROS and especially DTT activity across the continent. Only a 4-fold difference was documented for DTT across the urban sites and a similar variance was documented for ROS, implying that chemical drivers of oxidative activity are relatively similar between sites. The ROS and DTT specific activity was greater at urban background sites (and also rural sites) than at urban canyon locations. PM3 dominated the size distribution of both ROS activity (86% of total) and DTT activity (76% of total), reflecting both the large contribution of PM3 to total PM mass levels and importantly the higher specific oxidative activity of the PM3 in comparison with the larger particles. The soluble fraction of total activity was very high for DTT (94%) as well as for ROS (64%) in the PM3. However in the larger PM size fractions the contributions of the insoluble components became increasingly significant. The dominance of the insoluble PM drivers of activity was particularly evident in the TNFα data, where the insoluble contribution to cytokine production could be 100-fold greater than that from soluble components. ROS and DTT activity were strongly correlated in the PM3 (r = 0

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-01

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

  5. Dry fractionation for production of functional pea protein concentrates

    NARCIS (Netherlands)

    Pelgrom, P.J.M.; Vissers, A.M.; Boom, R.M.; Schutyser, M.A.I.

    2013-01-01

    Dry milling in combination with air classification was evaluated as an alternative to conventional wet extraction of protein from yellow field peas (Pisum sativum). Major advantages of dry fractionation are retention of native functionality of proteins and its lower energy and water use. Peas were

  6. Nitrogen uptake by size-fractionated phytoplankton in mangrove waters

    Digital Repository Service at National Institute of Oceanography (India)

    Dham, V.V.; Wafar, M.V.M.; Heredia, A.M.

    to January — dry and cool) and pre-monsoon (February to May — dry and hot) periods. Environmental parameters, the nutrients and rates of N uptake and the remineralisation by unfractionated plankton were measured at 3 stations (Fig. 1) over a series of 16... samples with netplankton (20 to 200 µm) and nanoplankton (0.8 to 20 µm) sized particles were obtained by serial filtration through 200 and 20 µm bolting silk and 0.8 µm glass-fibre filters, and were used for measurements of chlorophyll a (chl a...

  7. Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives

    International Nuclear Information System (INIS)

    Contado, Catia; Ravani, Laura; Passarella, Martina

    2013-01-01

    Graphical abstract: -- Highlights: •Four types of SiO 2 particles were characterized by SdFFF, PCS and EM techniques. •Clusters of 10 nm nanoparticles were found in some SiO 2 samples. •A method was set up to extract SiO 2 particles from food matrices. •The effects of the carrier solution composition on SdFFF separations were evaluated. •Particle size distributions were obtained from SiO 2 particles extracted from foodstuffs. -- Abstract: Four types of SiO 2 , available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w −1 ) a nearly silica-free instant barley coffee powder with a known SiO 2 sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO 2 particles and verify the new particle size distribution. The SiO 2 content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w −1 ). The protocol to isolate the silica particles was so applied to the most SiO 2 -rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification

  8. Distribution of artificial radionuclides in particle-size fractions of soil on fallout plumes of nuclear explosions.

    Science.gov (United States)

    Kabdyrakova, A M; Lukashenko, S N; Mendubaev, A T; Kunduzbayeva, A Ye; Panitskiy, A V; Larionova, N V

    2018-06-01

    In this paper are analyzed the artificial radionuclide distributions ( 137 Cs, 90 Sr, 241 Am, 239+240 Pu) in particle-size fractions of soils from two radioactive fallout plumes at the Semipalatinsk Test Site. These plumes were generated by a low-yield surface nuclear test and a surface non-nuclear experiment with insignificant nuclear energy release, respectively, and their lengths are approximately 3 and 0,65 km. In contrast with the great majority of similar studies performed in areas affected mainly by global fallout where adsorbing radionuclides such as Pu are mainly associated with the finest soil fractions, in this study it was observed that along both analyzed plumes the highest activity concentrations are concentrated in the coarse soil fractions. At the plume generated by the surface nuclear test, the radionuclides are concentrated mainly in the 1000-500 μm soil fraction (enrichment factor values ranging from 1.2 to 3.8), while at the plume corresponding to the surface non-nuclear test is the 500-250 μm soil fraction the enriched one by technogenic radionuclides (enrichment factor values ranging from 1.1 to 5.1). In addition, the activity concentration distributions among the different soil size fractions are similar for all radionuclides in both plumes. All the obtained data are in agreement with the hypothesis indicating that enrichment observed in the coarse fractions is caused by the presence of radioactive particles resulted from the indicated nuclear tests. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Production of Concentrated Pickering Emulsions with Narrow Size Distributions Using Stirred Cell Membrane Emulsification.

    Science.gov (United States)

    Manga, Mohamed S; York, David W

    2017-09-12

    Stirred cell membrane emulsification (SCME) has been employed to prepare concentrated Pickering oil in water emulsions solely stabilized by fumed silica nanoparticles. The optimal conditions under which highly stable and low-polydispersity concentrated emulsions using the SCME approach are highlighted. Optimization of the oil flux rates and the paddle stirrer speeds are critical to achieving control over the droplet size and size distribution. Investigating the influence of oil volume fraction highlights the criticality of the initial particle loading in the continuous phase on the final droplet size and polydispersity. At a particle loading of 4 wt %, both the droplet size and polydispersity increase with increasing of the oil volume fraction above 50%. As more interfacial area is produced, the number of particles available in the continuous phase diminishes, and coincidently a reduction in the kinetics of particle adsorption to the interface resulting in larger polydisperse droplets occurs. Increasing the particle loading to 10 wt % leads to significant improvements in both size and polydispersity with oil volume fractions as high as 70% produced with coefficient of variation values as low as ∼30% compared to ∼75% using conventional homogenization techniques.

  10. Bacterial density and community structure associated with aggregate size fractions of soil-feeding termite mounds.

    Science.gov (United States)

    Fall, S; Nazaret, S; Chotte, J L; Brauman, A

    2004-08-01

    The building and foraging activities of termites are known to modify soil characteristics such as the heterogeneity. In tropical savannas the impact of the activity of soil-feeding termites ( Cubitermes niokoloensis) has been shown to affect the properties of the soil at the aggregate level by creating new soil microenvironments (aggregate size fractions) [13]. These changes were investigated in greater depth by looking at the microbial density (AODC) and the genetic structure (automated rRNA intergenic spacer analysis: ARISA) of the communities in the different aggregate size fractions (i.e., coarse sand, fine sand, coarse silt, fine silt, and dispersible clays) separated from compartments (internal and external wall) of three Cubitermes niokoloensis mounds. The bacterial density of the mounds was significantly higher (1.5 to 3 times) than that of the surrounding soil. Within the aggregate size fractions, the termite building activity resulted in a significant increase in bacterial density within the coarser fractions (>20 mum). Multivariate analysis of the ARISA profiles revealed that the bacterial genetic structures of unfractionated soil and soil aggregate size fractions of the three mounds was noticeably different from the savanna soil used as a reference. Moreover, the microbial community associated with the different microenvironments in the three termite mounds revealed three distinct clusters formed by the aggregate size fractions of each mound. Except for the 2-20 mum fraction, these results suggest that the mound microbial genetic structure is more dependent upon microbial pool affiliation (the termite mound) than on the soil location (aggregate size fraction). The causes of the specificity of the microbial community structure of termite mound aggregate size fractions are discussed.

  11. Micro nutrient status and their distribution in aggregate-size fractions ...

    African Journals Online (AJOL)

    Micro nutrients are particularly sensitive to changes in land use and their availability in soil is influenced by their distribution and storage in stable aggregate fractions. Micro nutrient, (Fe, Mn and Zn) status and their storage in stable aggregate-size fractions in forested, rubber plantation, oil palm plantation, plantain plantation ...

  12. ANALYSIS OF RESPIRATORY DESPOSITION DOSE OF INHALED AMBIENT AEROSOLS FOR DIFFERENT SIZE FRACTIONS

    Science.gov (United States)

    ANALYSIS OF RESPIRATORY DEPOSITION DOSE OF INHALED AMBIENT AEROSOLS FOR DIFFERENT SIZE FRACTIONS. Chong S. Kim, SC. Hu**, PA Jaques*, US EPA, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC 27711; **IIT Research Institute, Chicago, IL; *S...

  13. Modelling size-fractionated primary production in the Atlantic Ocean from remote sensing

    Science.gov (United States)

    Brewin, Robert J. W.; Tilstone, Gavin H.; Jackson, Thomas; Cain, Terry; Miller, Peter I.; Lange, Priscila K.; Misra, Ankita; Airs, Ruth L.

    2017-11-01

    Marine primary production influences the transfer of carbon dioxide between the ocean and atmosphere, and the availability of energy for the pelagic food web. Both the rate and the fate of organic carbon from primary production are dependent on phytoplankton size. A key aim of the Atlantic Meridional Transect (AMT) programme has been to quantify biological carbon cycling in the Atlantic Ocean and measurements of total primary production have been routinely made on AMT cruises, as well as additional measurements of size-fractionated primary production on some cruises. Measurements of total primary production collected on the AMT have been used to evaluate remote-sensing techniques capable of producing basin-scale estimates of primary production. Though models exist to estimate size-fractionated primary production from satellite data, these have not been well validated in the Atlantic Ocean, and have been parameterised using measurements of phytoplankton pigments rather than direct measurements of phytoplankton size structure. Here, we re-tune a remote-sensing primary production model to estimate production in three size fractions of phytoplankton (10 μm) in the Atlantic Ocean, using measurements of size-fractionated chlorophyll and size-fractionated photosynthesis-irradiance experiments conducted on AMT 22 and 23 using sequential filtration-based methods. The performance of the remote-sensing technique was evaluated using: (i) independent estimates of size-fractionated primary production collected on a number of AMT cruises using 14C on-deck incubation experiments and (ii) Monte Carlo simulations. Considering uncertainty in the satellite inputs and model parameters, we estimate an average model error of between 0.27 and 0.63 for log10-transformed size-fractionated production, with lower errors for the small size class (10 μm), and errors generally higher in oligotrophic waters. Application to satellite data in 2007 suggests the contribution of cells 2 μm to total

  14. Particle size fractionation and human exposure of polybrominated diphenyl ethers in indoor dust from Chicago.

    Science.gov (United States)

    Wei, Hua; Turyk, Mary; Cali, Salvatore; Dorevitch, Samuel; Erdal, Serap; Li, An

    2009-11-01

    The objective of this study was to investigate the concentration level, the mass distribution based on dust particle size, and the associated human exposure of polybrominated diphenyl ethers (PBDEs) in indoor dust. The total concentration of 13 PBDEs Sigma(13)(BDEs) was found to be 500-6,944 ng/g in indoor dusts, 4,000 ng/g in car interior dust, 260-300 ng/g in outdoor ambient air particles, 30 ng/g in carpet fibers, and as high as 0.5% in carpet padding. Selected dust samples were fractionated based on particle size, and over 80% of the Sigma(13)BDEs were associated with particles exposure of Americans to PBDEs via hand-to-mouth transfer of house dust was estimated under the central tendency exposure and reasonable maximum exposure scenarios. The results suggest that ingestion of PBDE-laden house dust via hand-to-mouth contact is likely a significant exposure pathway, especially for children.

  15. Experimental determination of the unattached radon daughter fraction and dust size distribution in some Canadian uranium mines

    International Nuclear Information System (INIS)

    Bigu, J.; Kirk, J.

    1982-01-01

    The unattached radon daughter fraction has been experimentally determined in some Canadian uranium mines. Two experimental methods have been used, the wire screen method and a diffusion sampler based on Mercer's theory of diffusional deposition on parallel circular plates. Experiments were conducted in 'non-diesel' and 'diesel' areas of the mines, i.e. locations where mining was done with diesel machinery. Unattached fractions ranged from about 2-8 per cent for non-diesel area. For diesel areas the unattached fraction was substantially lower, less than about one per cent. The aerosol concentration in the range 0.0015 - 0.13 μm was measured with a condensation nuclei counter. Dust concentration was determined with conventional samplers. Particle size distribution in the respirable range was determined with a fine particle spectrometer in conjunction with eriometric techniques

  16. Analysis of hard coal quality for narrow size fraction under 20 mm

    Science.gov (United States)

    Niedoba, Tomasz; Pięta, Paulina

    2018-01-01

    The paper presents the results of an analysis of hard coal quality diversion in narrow size fraction by using taxonomic methods. Raw material samples were collected in selected mines of Upper Silesian Industrial Region and they were classified according to the Polish classification as types 31, 34.2 and 35. Then, each size fraction was characterized in terms of the following properties: density, ash content, calorific content, volatile content, total sulfur content and analytical moisture. As a result of the analysis it can be stated that the best quality in the entire range of the tested size fractions was the 34.2 coking coal type. At the same time, in terms of price parameters, high quality of raw material characterised the following size fractions: 0-6.3 mm of 31 energetic coal type and 0-3.15 mm of 35 coking coal type. The methods of grouping (Ward's method) and agglomeration (k-means method) have shown that the size fraction below 10 mm was characterized by higher quality in all the analyzed hard coal types. However, the selected taxonomic methods do not make it possible to identify individual size fraction or hard coal types based on chosen parameters.

  17. Metagenomic analysis of size-fractionated picoplankton in a marine oxygen minimum zone.

    Science.gov (United States)

    Ganesh, Sangita; Parris, Darren J; DeLong, Edward F; Stewart, Frank J

    2014-01-01

    Marine oxygen minimum zones (OMZs) support diverse microbial communities with roles in major elemental cycles. It is unclear how the taxonomic composition and metabolism of OMZ microorganisms vary between particle-associated and free-living size fractions. We used amplicon (16S rRNA gene) and shotgun metagenome sequencing to compare microbial communities from large (>1.6 μm) and small (0.2-1.6 μm) filter size fractions along a depth gradient in the OMZ off Chile. Despite steep vertical redox gradients, size fraction was a significantly stronger predictor of community composition compared to depth. Phylogenetic diversity showed contrasting patterns, decreasing towards the anoxic OMZ core in the small size fraction, but exhibiting maximal values at these depths within the larger size fraction. Fraction-specific distributions were evident for key OMZ taxa, including anammox planctomycetes, whose coding sequences were enriched up to threefold in the 0.2-1.6 μm community. Functional gene composition also differed between fractions, with the >1.6 μm community significantly enriched in genes mediating social interactions, including motility, adhesion, cell-to-cell transfer, antibiotic resistance and mobile element activity. Prokaryotic transposase genes were three to six fold more abundant in this fraction, comprising up to 2% of protein-coding sequences, suggesting that particle surfaces may act as hotbeds for transposition-based genome changes in marine microbes. Genes for nitric and nitrous oxide reduction were also more abundant (three to seven fold) in the larger size fraction, suggesting microniche partitioning of key denitrification steps. These results highlight an important role for surface attachment in shaping community metabolic potential and genome content in OMZ microorganisms.

  18. Measurement of concentration and size distribution of radon decay products in homes using air cleaners

    International Nuclear Information System (INIS)

    Montassier, N.; Hopke, P.K.; Shi, Y.; McCallum, B.

    1992-01-01

    By removing particles, air cleaners can also eliminate radon decay products. However, by removing the particles, the open-quotes unattachedclose quotes fraction of the radon progeny is increased leading to a higher dose per unit exposure. Thus, both the concentration and size distributions of the radon decay products are needed to evaluate air cleaners. Three types of room air cleaners, NO-RAD Radon Removal System, Electronic Air Cleaner and PUREFLOW Air Treatment System were tested in a single family home in Arnprior, Ontario (Canada). Semi-continuous measurements of radon gas concentration and radon decay product activity weighted size distribution were performed in the kitchen/dining room under real living conditions. The effects of air cleaners on both the concentration and size distribution of the radon decay products were measured, and their impact on the dose of radiation given to the lung tissue were examined

  19. The effects of gold nanoparticles size and concentration on viscosity ...

    African Journals Online (AJOL)

    This study was carried out to investigate viscosity in relation with the temperature, flow activation energy and dielectric properties for 10, 20 and 50 nm gold nanoparticles size (GNPs) in addition to absorption and fluorescence spectra at different concentrations (0.2 × 10-3 to 1 × 10-2%) in an attempt to cover and understand ...

  20. Colloidal transport of uranium in soil: Size fractionation and characterization by field-flow fractionation-multi-detection

    International Nuclear Information System (INIS)

    Claveranne-Lamolere, C.; Lespes, G.; Dubascoux, St.; Potin-Gautier, M.; Claveranne-Lamolere, C.; Aupiais, J.; Pointurier, F.

    2009-01-01

    The aim of this study was to characterize colloids associated with uranium by using an on-line fractionation/multi-detection technique based on asymmetrical flow field-flow fractionation (As-Fl-FFF) hyphenated with UV detector, multi angle laser light scattering (MALLS) and inductively coupling plasma-mass spectrometry (ICP-MS). Moreover, thanks to the As-Fl-FFF, the different colloidal fractions were collected and characterized by a total organic carbon analyzer (TOC). Thus it is possible to determine the nature (organic or inorganic colloids), molar mass, size (gyration and hydrodynamic radii) and quantitative uranium distribution over the whole colloidal phase. In the case of the site studied, two populations are highlighted. The first population corresponds to humic-like substances with a molar mass of (1500 ± 300) g mol -1 and a hydrodynamic diameter of (2. 0 ± 0. 2) nm. The second one has been identified as a mix of carbonated nano-particles or clays with organic particles (aggregates and/or coating of the inorganic particles) with a size range hydrodynamic diameter between 30 and 450 nm. Each population is implied in the colloidal transport of uranium: maximum 1% of the uranium content in soil leachate is transported by the colloids in the site studied, according to the depth in the soil. Indeed, humic substances are the main responsible of this transport in sub-surface conditions whereas nano-particles drive the phenomenon in depth conditions. (authors)

  1. Impact of radiation therapy fraction size on local control of early glottic carcinoma

    International Nuclear Information System (INIS)

    Yu, Edward; Shenouda, George; Beaudet, Marie P.; Black, Martin J.

    1997-01-01

    Purpose: Different radiotherapy fractionation schedules were used over a 10-year period to treat patients with early squamous cell carcinoma of the vocal cords at McGill University. A retrospective analysis was performed to study the effect of fraction size on local control in this group of patients. Methods and Materials: A total of 126 previously untreated patients with T1 invasive squamous cell carcinoma of the true vocal cords were irradiated between January 1978 and December 1988 in the Department of Radiation Oncology at McGill University. All patients received megavoltage irradiation, 94 patients received daily fractions > 2 Gy (64 patients received 50 Gy with once-daily 2.5-Gy fractions, and 30 received 65.25 Gy in 29 fractions of 2.25 Gy each), and 32 patients were treated to a dose of 66 Gy in 33 fractions with 2 Gy/fraction. Patients' characteristics of prognostic importance were equally distributed between the two fractionation groups. Results: At a median follow-up of 84 months, the 10-year disease-free survival and overall survival were 76% and 93%, respectively. Local control for patients treated with > 2 Gy fraction was 84%, compared to 65.6% for those treated with 2-Gy fractions (p = 0.026). Among the prognostic factors tested, such as gender, age, stage, anterior and posterior commissure involvement, smoking history, and fraction size, the latter was the only significant predictor of local control for the whole group of patients in univariate (p = 0.041) and multivariate (p = 0.023) analysis. There was no observed difference in the incidence of complications between the two fraction groups. Conclusions: From the results of this retrospective review of patients treated with radiotherapy for T1 true vocal cord cancer, and within the range of total doses and overall treatment times used in our patients, it was found that fractionation schedules using daily fraction size > 2 Gy are associated with a better local control than schedules delivering 2 Gy/fraction

  2. Concentration, size, and density of total suspended particulates at the air exhaust of concentrated animal feeding operations.

    Science.gov (United States)

    Yang, Xufei; Lee, Jongmin; Zhang, Yuanhui; Wang, Xinlei; Yang, Liangcheng

    2015-08-01

    Total suspended particulate (TSP) samples were seasonally collected at the air exhaust of 15 commercial concentrated animal feeding operations (CAFOs; including swine finishing, swine farrowing, swine gestation, laying hen, and tom turkey) in the U.S. Midwest. The measured TSP concentrations ranged from 0.38 ± 0.04 mg m⁻³ (swine gestation in summer) to 10.9 ± 3.9 mg m⁻³ (tom turkey in winter) and were significantly affected by animal species, housing facility type, feeder type (dry or wet), and season. The average particle size of collected TSP samples in terms of mass median equivalent spherical diameter ranged from 14.8 ± 0.5 µm (swine finishing in winter) to 30.5 ± 2.0 µm (tom turkey in summer) and showed a significant seasonal effect. This finding affirmed that particulate matter (PM) released from CAFOs contains a significant portion of large particles. The measured particle size distribution (PSD) and the density of deposited particles (on average 1.65 ± 0.13 g cm⁻³) were used to estimate the mass fractions of PM10 and PM2.5 (PM ≤ 10 and ≤ 2.5 μm, respectively) in the collected TSP. The results showed that the PM10 fractions ranged from 12.7 ± 5.1% (tom turkey) to 21.1 ± 3.2% (swine finishing), whereas the PM2.5 fractions ranged from 3.4 ± 1.9% (tom turkey) to 5.7 ± 3.2% (swine finishing) and were smaller than 9.0% at all visited CAFOs. This study applied a filter-based method for PSD measurement and deposited particles as a surrogate to estimate the TSP's particle density. The limitations, along with the assumptions adopted during the calculation of PM mass fractions, must be recognized when comparing the findings to other studies.

  3. Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives

    Energy Technology Data Exchange (ETDEWEB)

    Contado, Catia, E-mail: Catia.Contado@unife.it [University of Ferrara, Department of Chemical and Pharmaceutical Sciences, via L. Borsari, 46, 44121 Ferrara (Italy); Ravani, Laura [University of Ferrara, Department of Life Sciences and Biotechnologies, via L. Borsari, 46, 44121 Ferrara (Italy); Passarella, Martina [University of Ferrara, Department of Chemical and Pharmaceutical Sciences, via L. Borsari, 46, 44121 Ferrara (Italy)

    2013-07-25

    Graphical abstract: -- Highlights: •Four types of SiO{sub 2} particles were characterized by SdFFF, PCS and EM techniques. •Clusters of 10 nm nanoparticles were found in some SiO{sub 2} samples. •A method was set up to extract SiO{sub 2} particles from food matrices. •The effects of the carrier solution composition on SdFFF separations were evaluated. •Particle size distributions were obtained from SiO{sub 2} particles extracted from foodstuffs. -- Abstract: Four types of SiO{sub 2}, available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w{sup −1}) a nearly silica-free instant barley coffee powder with a known SiO{sub 2} sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO{sub 2} particles and verify the new particle size distribution. The SiO{sub 2} content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w{sup −1}). The protocol to isolate the silica particles was so applied to the most SiO{sub 2}-rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification.

  4. Prediction of size-fractionated airborne particle-bound metals using MLR, BP-ANN and SVM analyses.

    Science.gov (United States)

    Leng, Xiang'zi; Wang, Jinhua; Ji, Haibo; Wang, Qin'geng; Li, Huiming; Qian, Xin; Li, Fengying; Yang, Meng

    2017-08-01

    Size-fractionated heavy metal concentrations were observed in airborne particulate matter (PM) samples collected from 2014 to 2015 (spanning all four seasons) from suburban (Xianlin) and industrial (Pukou) areas in Nanjing, a megacity of southeast China. Rapid prediction models of size-fractionated metals were established based on multiple linear regression (MLR), back propagation artificial neural network (BP-ANN) and support vector machine (SVM) by using meteorological factors and PM concentrations as input parameters. About 38% and 77% of PM 2.5 concentrations in Xianlin and Pukou, respectively, were beyond the Chinese National Ambient Air Quality Standard limit of 75 μg/m 3 . Nearly all elements had higher concentrations in industrial areas, and in winter among the four seasons. Anthropogenic elements such as Pb, Zn, Cd and Cu showed larger percentages in the fine fraction (ø≤2.5 μm), whereas the crustal elements including Al, Ba, Fe, Ni, Sr and Ti showed larger percentages in the coarse fraction (ø > 2.5 μm). SVM showed a higher training correlation coefficient (R), and lower mean absolute error (MAE) as well as lower root mean square error (RMSE), than MLR and BP-ANN for most metals. All the three methods showed better prediction results for Ni, Al, V, Cd and As, whereas relatively poor for Cr and Fe. The daily airborne metal concentrations in 2015 were then predicted by the fully trained SVM models and the results showed the heaviest pollution of airborne heavy metals occurred in December and January, whereas the lightest pollution occurred in June and July. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Investigation of magnetic active core sizes and hydrodynamic diameters of a magnetically fractionated ferrofluid

    International Nuclear Information System (INIS)

    Büttner, Markus; Weber, Peter; Schmidl, Frank; Seidel, Paul; Röder, Michael; Schnabelrauch, Matthias; Wagner, Kerstin; Görnert, Peter; Glöckl, Gunnar; Weitschies, Werner

    2011-01-01

    In this work we address the question which relates between the size of the magnetically active core of magnetic nanoparticles (MNPs) and the size of the overall particle in the solution (the so-called hydrodynamic diameter d hyd ) exists. For this purpose we use two methods of examination that can deliver conclusions about the properties of MNP which are not accessible with normal microscopy. On the one hand, we use temperature dependent magnetorelaxation (TMRX) method, which enables direct access to the energy barrier distribution and by using additional hysteresis loop measurements can provide details about the size of the magnetically active cores. On the other hand, to determine the size of the overall particle in the solution, we use the magnetooptical relaxation of ferrofluids (MORFF) method, where the stimulation is done magnetically while the reading of the relaxation signal, however, is done optically. As a basis for the examinations in this work we use a ferrofluid that was developed for medicinal purposes and which has been fractioned magnetically to obtain differently sized fractions of MNPs. The two values obtained through these methods for each fraction shows the success in fractioning the original solution. Therefore, one can conclude a direct correlation between the size of the magnetically active core and the size of the complete particle in the solution from the experimental results. To calculate the size of the magnetically active core we found a temperature dependent anisotropy constant which was taken into account for the calculations. Furthermore, we found relaxation signals at 18 K for all fractions in these TMRX measurements, which have their origin in other magnetic effects than the Néel relaxation.

  6. Changes in carbon stability and microbial activity in size fractions of micro-aggregates in a rice soil chronosequence under long term rice cultivation

    Science.gov (United States)

    Pan, Genxing; Liu, Yalong; Wang, Ping; Li, Lianqinfg; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Bian, Rongjun; Ding, Yuanjun; Ma, Chong

    2016-04-01

    Recent studies have shown soil carbon sequestration through physical protection of relative labile carbon intra micro-aggregates with formation of large sized macro-aggregates under good management of soil and agricultural systems. While carbon stabilization had been increasingly concerned as ecosystem properties, the mechanisms underspin bioactivity of soil carbon with increased carbon stability has been still poorly understood. In this study, topsoil samples were collected from rice soils derived from salt marsh under different length of rice cultivation up to 700 years from eastern China. Particle size fractions (PSF) of soil aggregates were separated using a low energy dispersion protocol. Carbon fractions in the PSFs were analyzed either with FTIR spectroscopy. Soil microbial community of bacterial, fungal and archaeal were analyzed with molecular fingerprinting using specific gene primers. Soil respiration and carbon gain from amended maize as well as enzyme activities were measured using lab incubation protocols. While the PSFs were dominated by the fine sand (200-20μm) and silt fraction (20-2μm), the mass proportion both of sand (2000-200μm) and clay (soil aggregates (also referred to aggregate stability). Soil organic carbon was found most enriched in coarse sand fraction (40-60g/kg), followed by the clay fraction (20-24.5g/kg), but depleted in the silt fraction (~10g/kg). Phenolic and aromatic carbon as recalcitrant pool were high (33-40% of total SOC) in both coarse sand and clay fractions than in both fine sand and silt fractions (20-29% of total SOC). However, the ratio of LOC/total SOC showed a weak decreasing trend with decreasing size of the aggregate fractions. Total gene content in the size fractions followed a similar trend to that of SOC. Bacterial and archaeal gene abundance was concentrated in both sand and clay fractions but that of fungi in sand fraction, and sharply decreased with the decreasing size of aggregate fraction. Gene abundance

  7. Modelling the fine and coarse fraction of Pb, Cd, As and Ni air concentration in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, M. A.; Vivanco, M. G.

    2015-07-01

    Lead, cadmium, arsenic and nickel are present in the air due to natural and anthropogenic emissions, normally joined to particles. Human health and ecosystems can be damaged by high atmospheric levels of these metals, since they can be introduced in organisms via inhalation or ingestion. Small particles are inhaled and embebed in lungs and alveolus more easily than coarse particles. The CHIMERE model is a eulerian air quality model extensively used in air quality modelling. Metals have been recently included in this model in a special version developed in the CIEMAT modelling group (Madrid, Spain). Vivanco et al. (2011) and Gonzalez et al. (2012) showed an evaluation of the model performance for some metals in Spain and Europe. In these studies, metals were considered as fine particles. Nevertheless there is some observational evidence of the presence of some metals also in the coarse fraction. For this reason, a new attempt of modelling metals considering a fine (<2.5 μm) and coarse (2.5-10 μm) fraction has been done. Measurements of metal concentration in PM10, PM2.5 and PM1 recorded in Spain were used to obtain the new metal particle distribution size. On the other hand, natural emissions, not considered in the above mentioned studies, were implemented in the model, by considering metal emissions associated to dust resuspensiont. An evaluation of the new version is presented and discussed for two domains in Spain, centered on Barcelona and Huelva respectively. (Author)

  8. Modelling the fine and coarse fraction of Pb, Cd, As and Ni air concentration in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, M.A.; Vivanco, M.

    2015-07-01

    Lead, cadmium, arsenic and nickel are present in the air due to natural and anthropogenic emissions, normally joined to particles. Human health and ecosystems can be damaged by high atmospheric levels of these metals, since they can be introduced in organisms via inhalation or ingestion. Small particles are inhaled and embebed in lungs and alveolus more easily than coarse particles. The CHIMERE model is a eulerian air quality model extensively used in air quality modelling. Metals have been recently included in this model in a special version developed in the CIEMAT modelling group (Madrid, Spain). Vivanco et al. (2011) and González et al. (2012) showed an evaluation of the model performance for some metals in Spain and Europe. In these studies, metals were considered as fine particles. Nevertheless there is some observational evidence of the presence of some metals also in the coarse fraction. For this reason, a new attempt of modelling metals considering a fine (<2.5 μm) and coarse (2.5-10 μm) fraction has been done. Measurements of metal concentration in PM10, PM2.5 and PM1 recorded in Spain were used to obtain the new metal particle distribution size. On the other hand, natural emissions, not considered in the above mentioned studies, were implemented in the model, by considering metal emissions associated to dust resuspensiont. An evaluation of the new version is presented and discussed for two domains in Spain, centered on Barcelona and Huelva respectively. (Author)

  9. Modelling the fine and coarse fraction of Pb, Cd, As and Ni air concentration in Spain

    International Nuclear Information System (INIS)

    Gonzalez, M. A.; Vivanco, M. G.

    2015-01-01

    Lead, cadmium, arsenic and nickel are present in the air due to natural and anthropogenic emissions, normally joined to particles. Human health and ecosystems can be damaged by high atmospheric levels of these metals, since they can be introduced in organisms via inhalation or ingestion. Small particles are inhaled and embebed in lungs and alveolus more easily than coarse particles. The CHIMERE model is a eulerian air quality model extensively used in air quality modelling. Metals have been recently included in this model in a special version developed in the CIEMAT modelling group (Madrid, Spain). Vivanco et al. (2011) and Gonzalez et al. (2012) showed an evaluation of the model performance for some metals in Spain and Europe. In these studies, metals were considered as fine particles. Nevertheless there is some observational evidence of the presence of some metals also in the coarse fraction. For this reason, a new attempt of modelling metals considering a fine (<2.5 μm) and coarse (2.5-10 μm) fraction has been done. Measurements of metal concentration in PM10, PM2.5 and PM1 recorded in Spain were used to obtain the new metal particle distribution size. On the other hand, natural emissions, not considered in the above mentioned studies, were implemented in the model, by considering metal emissions associated to dust resuspensiont. An evaluation of the new version is presented and discussed for two domains in Spain, centered on Barcelona and Huelva respectively. (Author)

  10. Distribution of volatile and non volatile elements in grain-size fractions of Apollo 17 drive tube 74001/2

    International Nuclear Information System (INIS)

    Kraehenbuehl, U.

    1980-01-01

    A study of four samples of double drive tube 74001/2 originating from 12, 25, 38, and 58 cm depths indicates that the concentrations of major and nonvolatile elements are fairly uniform for the four layers and the individual size fractions, while volatile elements as well as Au and Ir are enriched in the smaller grain-size fractions. It is concluded from the measured Au/Ir ratios and from the absence of a surface enrichment of Co that the material in the drive tube 74001/2 is not the result of an impact of an iron meteorite into a lava lake, but originated in at least three volcanic eruptions. No indication of a later disturbance of the stratigraphy of the layers is observed. Exposure ages of 345,000 and 225,000 years result from Ir deposits for the two layers of 74002

  11. Using fractional extraction method to separate Mo from U in high concentration solution

    International Nuclear Information System (INIS)

    Zhao Pinzhi; Cheng Guangrong; Ma Xiuhua

    1996-01-01

    The author presents investigation on separating Mo from U in acid high concentration lixivium with fractional extraction of secondary amine (7203) and D2EHPA and preparing qualified products of ammonium molybdate and sodium diuranate

  12. Season, molt, and body size influence mercury concentrations in grebes.

    Science.gov (United States)

    Hartman, C Alex; Ackerman, Joshua T; Herzog, Mark P; Eagles-Smith, Collin A

    2017-10-01

    We studied seasonal and physiological influences on mercury concentrations in western grebes (Aechmophorus occidentalis) and Clark's grebes (A. occidentalis) across 29 lakes and reservoirs in California, USA. Additionally, at three of these lakes, we conducted a time series study, in which we repeatedly sampled grebe blood mercury concentrations during the spring, summer, and early fall. Grebe blood mercury concentrations were higher among males (0.61 ± 0.12 μg/g ww) than females (0.52 ± 0.10 μg/g ww), higher among Clark's grebes (0.58 ± 0.12 μg/g ww) than western grebes (0.51 ± 0.10 μg/g ww), and exhibited a strong seasonal pattern (decreasing by 60% from spring to fall). Grebe blood THg concentrations exhibited a shallow, inverse U-shaped pattern with body size, and was lowest among the smallest and largest grebes. Further, the relationship between grebe blood mercury concentrations and wing primary feather molt exhibited a shallow U-shaped pattern, where mercury concentrations were highest among birds that had not yet begun molting, decreased approximately 24% between pre-molt and late molt, and increased approximately 19% from late molt to post-molt. Because grebes did not begin molting until mid-summer, lower grebe blood mercury concentrations observed in late summer and early fall were consistent with the onset of primary feather molt. However, because sampling date was a much stronger predictor of grebe mercury concentrations than molt, other seasonally changing environmental factors likely played a larger role than molt in the seasonal variation in grebe mercury concentrations. In the time series study, we found that seasonal trends in grebe mercury concentrations were not consistent among lakes, indicating that lake-specific variation in mercury dynamics influence the overall seasonal decline in grebe blood mercury concentrations. These results highlight the importance of accounting for sampling date, as well as ecological processes

  13. Season, molt, and body size influence mercury concentrations in grebes

    Science.gov (United States)

    Hartman, Christopher; Ackerman, Joshua T.; Herzog, Mark; Eagles-Smith, Collin A.

    2017-01-01

    We studied seasonal and physiological influences on mercury concentrations in western grebes (Aechmophorus occidentalis) and Clark's grebes (A. occidentalis) across 29 lakes and reservoirs in California, USA. Additionally, at three of these lakes, we conducted a time series study, in which we repeatedly sampled grebe blood mercury concentrations during the spring, summer, and early fall. Grebe blood mercury concentrations were higher among males (0.61 ± 0.12 μg/g ww) than females (0.52 ± 0.10 μg/g ww), higher among Clark's grebes (0.58 ± 0.12 μg/g ww) than western grebes (0.51 ± 0.10 μg/g ww), and exhibited a strong seasonal pattern (decreasing by 60% from spring to fall). Grebe blood THg concentrations exhibited a shallow, inverse U-shaped pattern with body size, and was lowest among the smallest and largest grebes. Further, the relationship between grebe blood mercury concentrations and wing primary feather molt exhibited a shallow U-shaped pattern, where mercury concentrations were highest among birds that had not yet begun molting, decreased approximately 24% between pre-molt and late molt, and increased approximately 19% from late molt to post-molt. Because grebes did not begin molting until mid-summer, lower grebe blood mercury concentrations observed in late summer and early fall were consistent with the onset of primary feather molt. However, because sampling date was a much stronger predictor of grebe mercury concentrations than molt, other seasonally changing environmental factors likely played a larger role than molt in the seasonal variation in grebe mercury concentrations. In the time series study, we found that seasonal trends in grebe mercury concentrations were not consistent among lakes, indicating that lake-specific variation in mercury dynamics influence the overall seasonal decline in grebe blood mercury concentrations. These results highlight the importance of accounting for sampling date, as well as ecological processes that may

  14. Metagenomic analysis of size-fractionated picoplankton in a marine oxygen minimum zone

    OpenAIRE

    Ganesh, Sangita; Parris, Darren J; DeLong, Edward F; Stewart, Frank J

    2013-01-01

    Marine oxygen minimum zones (OMZs) support diverse microbial communities with roles in major elemental cycles. It is unclear how the taxonomic composition and metabolism of OMZ microorganisms vary between particle-associated and free-living size fractions. We used amplicon (16S rRNA gene) and shotgun metagenome sequencing to compare microbial communities from large (>1.6 μm) and small (0.2–1.6 μm) filter size fractions along a depth gradient in the OMZ off Chile. Despite steep vertical redox ...

  15. Arsenic partitioning among particle-size fractions of mine wastes and stream sediments from cinnabar mining districts.

    Science.gov (United States)

    Silva, Veronica; Loredo, Jorge; Fernández-Martínez, Rodolfo; Larios, Raquel; Ordóñez, Almudena; Gómez, Belén; Rucandio, Isabel

    2014-10-01

    Tailings from abandoned mercury mines represent an important pollution source by metals and metalloids. Mercury mining in Asturias (north-western Spain) has been carried out since Roman times until the 1970s. Specific and non-specific arsenic minerals are present in the paragenesis of the Hg ore deposit. As a result of intensive mining operations, waste materials contain high concentrations of As, which can be geochemically dispersed throughout surrounding areas. Arsenic accumulation, mobility and availability in soils and sediments are strongly affected by the association of As with solid phases and granular size composition. The objective of this study was to examine phase associations of As in the fine grain size subsamples of mine wastes (La Soterraña mine site) and stream sediments heavily affected by acid mine drainage (Los Rueldos mine site). An arsenic-selective sequential procedure, which categorizes As content into seven phase associations, was applied. In spite of a higher As accumulation in the finest particle-size subsamples, As fractionation did not seem to depend on grain size since similar distribution profiles were obtained for the studied granulometric fractions. The presence of As was relatively low in the most mobile forms in both sites. As was predominantly linked to short-range ordered Fe oxyhydroxides, coprecipitated with Fe and partially with Al oxyhydroxides and associated with structural material in mine waste samples. As incorporated into short-range ordered Fe oxyhydroxides was the predominant fraction at sediment samples, representing more than 80% of total As.

  16. Molecular diversity patterns among various phytoplankton size-fractions in West Greenland in late summer

    Science.gov (United States)

    Elferink, Stephanie; Neuhaus, Stefan; Wohlrab, Sylke; Toebe, Kerstin; Voß, Daniela; Gottschling, Marc; Lundholm, Nina; Krock, Bernd; Koch, Boris P.; Zielinski, Oliver; Cembella, Allan; John, Uwe

    2017-03-01

    Arctic regions have experienced pronounced biological and biophysical transformations as a result of global change processes over the last several decades. Current hypotheses propose an elevated impact of those environmental changes on the biodiversity, community composition and metabolic processes of species. The effects on ecosystem function and services, particularly when invasive or toxigenic harmful species become dominant, can be expressed over a wide range of temporal and spatial scales in plankton communities. Our study focused on the comparison of molecular biodiversity of three size-fractions (micro-, nano-, picoplankton) in the coastal pelagic zone of West Greenland and their association with environmental parameters. Molecular diversity was assessed via parallel amplicon sequencing the 28S rRNA hypervariable D1/D2 region. We showed that biodiversity distribution within the area of Uummannaq Fjord, Vaigat Strait and Disko Bay differed markedly within and among size-fractions. In general, we observed a higher diversity within the picoplankton size fraction compared to the nano- and microplankton. In multidimensional scaling analysis, community composition of all three size fractions correlated with cell size, silicate and phosphate, chlorophyll a (chl a) and dinophysistoxin (DTX). Individually, each size fraction community composition also correlated with other different environmental parameters, i.e. temperature and nitrate. We observed a more homogeneous community of the picoplankton across all stations compared to the larger size classes, despite different prevailing environmental conditions of the sampling areas. This suggests that habitat niche occupation for larger-celled species may lead to higher functional trait plasticity expressed as an enhanced range of phenotypes, whereas smaller organisms may compensate for lower potential plasticity with higher diversity. The presence of recently identified toxigenic harmful algal bloom (HAB) species (such

  17. Stable Carbon Fractionation In Size Segregated Aerosol Particles Produced By Controlled Biomass Burning

    Science.gov (United States)

    Masalaite, Agne; Garbaras, Andrius; Garbariene, Inga; Ceburnis, Darius; Martuzevicius, Dainius; Puida, Egidijus; Kvietkus, Kestutis; Remeikis, Vidmantas

    2014-05-01

    Biomass burning is the largest source of primary fine fraction carbonaceous particles and the second largest source of trace gases in the global atmosphere with a strong effect not only on the regional scale but also in areas distant from the source . Many studies have often assumed no significant carbon isotope fractionation occurring between black carbon and the original vegetation during combustion. However, other studies suggested that stable carbon isotope ratios of char or BC may not reliably reflect carbon isotopic signatures of the source vegetation. Overall, the apparently conflicting results throughout the literature regarding the observed fractionation suggest that combustion conditions may be responsible for the observed effects. The purpose of the present study was to gather more quantitative information on carbonaceous aerosols produced in controlled biomass burning, thereby having a potential impact on interpreting ambient atmospheric observations. Seven different biomass fuel types were burned under controlled conditions to determine the effect of the biomass type on the emitted particulate matter mass and stable carbon isotope composition of bulk and size segregated particles. Size segregated aerosol particles were collected using the total suspended particle (TSP) sampler and a micro-orifice uniform deposit impactor (MOUDI). The results demonstrated that particle emissions were dominated by the submicron particles in all biomass types. However, significant differences in emissions of submicron particles and their dominant sizes were found between different biomass fuels. The largest negative fractionation was obtained for the wood pellet fuel type while the largest positive isotopic fractionation was observed during the buckwheat shells combustion. The carbon isotope composition of MOUDI samples compared very well with isotope composition of TSP samples indicating consistency of the results. The measurements of the stable carbon isotope ratio in

  18. Inflammation response and cytotoxic effects in human THP-1 cells of size-fractionated PM10 extracts in a polluted urban site.

    Science.gov (United States)

    Schilirò, T; Alessandria, L; Bonetta, S; Carraro, E; Gilli, G

    2016-02-01

    To contribute to a greater characterization of the airborne particulate matter's toxicity, size-fractionated PM10 was sampled during different seasons in a polluted urban site in Torino, a northern Italian city. Three main size fractions (PM10 - 3 μm; PM3 - 0.95 μm; PM THP-1 cells to evaluate their effects on cell proliferation, LDH activity, TNFα, IL-8 and CYP1A1 expression. The mean PM10 concentrations were statistically different in summer and in winter and the finest fraction PMtest) that could be used in the context of the different monitoring programs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Carbon storage in soil size fractions under two cacao agroforestry systems in Bahia, Brazil.

    Science.gov (United States)

    Gama-Rodrigues, Emanuela F; Ramachandran Nair, P K; Nair, Vimala D; Gama-Rodrigues, Antonio C; Baligar, Virupax C; Machado, Regina C R

    2010-02-01

    Shaded perennial agroforestry systems contain relatively high quantities of soil carbon (C) resulting from continuous deposition of plant residues; however, the extent to which the C is sequestered in soil will depend on the extent of physical protection of soil organic C (SOC). The main objective of this study was to characterize SOC storage in relation to soil fraction-size classes in cacao (Theobroma cacao L.) agroforestry systems (AFSs). Two shaded cacao systems and an adjacent natural forest in reddish-yellow Oxisols in Bahia, Brazil were selected. Soil samples were collected from four depth classes to 1 m depth and separated by wet-sieving into three fraction-size classes (>250 microm, 250-53 microm, and <53 microm)-corresponding to macroaggregate, microaggregate, and silt-and-clay size fractions-and analyzed for C content. The total SOC stock did not vary among systems (mean: 302 Mg/ha). On average, 72% of SOC was in macroaggregate-size, 20% in microaggregate-size, and 8% in silt-and-clay size fractions in soil. Sonication of aggregates showed that occlusion of C in soil aggregates could be a major mechanism of C protection in these soils. Considering the low level of soil disturbances in cacao AFSs, the C contained in the macroaggregate fraction might become stabilized in the soil. The study shows the role of cacao AFSs in mitigating greenhouse gas (GHG) emission through accumulation and retention of high amounts of organic C in the soils and suggests the potential benefit of this environmental service to the nearly 6 million cacao farmers worldwide.

  20. Elemental analysis of size-fractionated particulate matter sampled in Goeteborg, Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Annemarie [Department of Chemistry, Atmospheric Science, Goeteborg University, SE-412 96 Goeteborg (Sweden)], E-mail: wagnera@chalmers.se; Boman, Johan [Department of Chemistry, Atmospheric Science, Goeteborg University, SE-412 96 Goeteborg (Sweden); Gatari, Michael J. [Institute of Nuclear Science and Technology, University of Nairobi, P.O. Box 30197-00100, Nairobi (Kenya)

    2008-12-15

    The aim of the study was to investigate the mass distribution of trace elements in aerosol samples collected in the urban area of Goeteborg, Sweden, with special focus on the impact of different air masses and anthropogenic activities. Three measurement campaigns were conducted during December 2006 and January 2007. A PIXE cascade impactor was used to collect particulate matter in 9 size fractions ranging from 16 to 0.06 {mu}m aerodynamic diameter. Polished quartz carriers were chosen as collection substrates for the subsequent direct analysis by TXRF. To investigate the sources of the analyzed air masses, backward trajectories were calculated. Our results showed that diurnal sampling was sufficient to investigate the mass distribution for Br, Ca, Cl, Cu, Fe, K, Sr and Zn, whereas a 5-day sampling period resulted in additional information on mass distribution for Cr and S. Unimodal mass distributions were found in the study area for the elements Ca, Cl, Fe and Zn, whereas the distributions for Br, Cu, Cr, K, Ni and S were bimodal, indicating high temperature processes as source of the submicron particle components. The measurement period including the New Year firework activities showed both an extensive increase in concentrations as well as a shift to the submicron range for K and Sr, elements that are typically found in fireworks. Further research is required to validate the quantification of trace elements directly collected on sample carriers.

  1. Elemental analysis of size-fractionated particulate matter sampled in Goeteborg, Sweden

    International Nuclear Information System (INIS)

    Wagner, Annemarie; Boman, Johan; Gatari, Michael J.

    2008-01-01

    The aim of the study was to investigate the mass distribution of trace elements in aerosol samples collected in the urban area of Goeteborg, Sweden, with special focus on the impact of different air masses and anthropogenic activities. Three measurement campaigns were conducted during December 2006 and January 2007. A PIXE cascade impactor was used to collect particulate matter in 9 size fractions ranging from 16 to 0.06 μm aerodynamic diameter. Polished quartz carriers were chosen as collection substrates for the subsequent direct analysis by TXRF. To investigate the sources of the analyzed air masses, backward trajectories were calculated. Our results showed that diurnal sampling was sufficient to investigate the mass distribution for Br, Ca, Cl, Cu, Fe, K, Sr and Zn, whereas a 5-day sampling period resulted in additional information on mass distribution for Cr and S. Unimodal mass distributions were found in the study area for the elements Ca, Cl, Fe and Zn, whereas the distributions for Br, Cu, Cr, K, Ni and S were bimodal, indicating high temperature processes as source of the submicron particle components. The measurement period including the New Year firework activities showed both an extensive increase in concentrations as well as a shift to the submicron range for K and Sr, elements that are typically found in fireworks. Further research is required to validate the quantification of trace elements directly collected on sample carriers

  2. Tribological Characteristics of Tungsten Carbide Reinforced Arc Sprayed Coatings using Different Carbide Grain Size Fractions

    Directory of Open Access Journals (Sweden)

    W. Tillmann

    2017-06-01

    Full Text Available Tungsten carbide reinforced coatings play an important role in the field of surface engineering to protect stressed surfaces against wear. For thermally sprayed coatings, it is already shown that the tribological properties get mainly determined by the carbide grain size fraction. Within the scope of this study, the tribological characteristics of iron based WC-W2C reinforced arc sprayed coatings deposited using cored wires consisting of different carbide grain size fractions were examined. Microstructural characteristics of the produced coatings were scrutinized using electron microscopy and x-ray diffraction analyses. Ball-on-disk test as well as Taber Abraser and dry sand rubber wheel test were employed to analyze both the dry sliding and the abrasive wear behavior. It was shown that a reduced carbide grain size fraction as filling leads to an enhanced wear resistance against sliding. In terms of the Taber Abraser test, it is also demonstrated that a fine carbide grain size fraction results in an improved wear resistant against abrasion. As opposed to that, a poorer wear resistance was found within the dry sand rubber wheel tests. The findings show that the operating mechanisms for both abrasion tests affect the stressed surface in a different way, leading either to microcutting or microploughing.

  3. Bacterial Preferences for Specific Soil Particle Size Fractions Revealed by Community Analyses

    DEFF Research Database (Denmark)

    Hemkemeyer, Michael; Dohrmann, Anja B.; Christensen, Bent Tolstrup

    2018-01-01

    , while Gemmatimonadales preferred coarse silt, Actinobacteria and Nitrosospira fine silt, and Planctomycetales clay. Firmicutes were depleted in the sand-sized fraction. In contrast, archaea, which represented 0.8% of all 16S rRNA gene sequences, showed only little preference for specific PSFs. We...

  4. Effects of anion size and concentration on electrolyte invasion into molecular-sized nanopores

    International Nuclear Information System (INIS)

    Liu Ling; Chen Xi; Kim, Taewan; Han Aijie; Qiao Yu

    2010-01-01

    When an electrolyte solution is pressurized into a molecular-sized nanopore, oppositely charged ions are strongly inclined to aggregate, which effectively reduces the ion solubility to zero. Inside the restrictive confinement, a unique quasi-periodic structure is formed where the paired ion couples are periodically separated by a number of water molecules. As the anion size or ion concentration varies, the geometrical characteristics of the confined ion structure would change considerably, leading to a significant variation in the transport pressure. Both experimental and simulation results indicate that, contradictory to the prediction of conventional theory, infiltration pressure decreases as the anions become larger.

  5. Size resolved mass concentration and elemental composition of atmospheric aerosols over the Eastern Mediterranean area

    Directory of Open Access Journals (Sweden)

    J. Smolík

    2003-01-01

    Full Text Available A Berner low pressure impactor was used to collect size-segregated aerosol samples at Finokalia, located on the north-eastern coast of Crete, Greece during July 2000 and January 2001. Several samples were also collected during the summer campaign aboard the research vessel "AEGAIEO" in the Aegean Sea. Gravimetric analysis and inversion techniques yielded daily PM1 and PM10 mass concentrations. The samples were also analysed by PIXE giving the elemental size distributions of Al, Si, K, Ca, Ti, Mn, Fe, Sr, S, Cl, Ni, V, Cu, Cr, Zn, and Pb. The crustal elements and sea-salt had a unimodal supermicron size distribution. Sulphur was found predominantly in submicron fractions. K, V, and Ni exhibited a bimodal distribution with a submicron mode produced by forest fires and oil combustion. The anthropogenic elements had broad and not well-defined distributions. The time series for PM1 and PM10 mass and elemental concentrations showed both daily and seasonal variation. Higher mass concentrations were observed during two incursions of Saharan dust, whilst higher concentrations of S, Cu, Zn, and Pb were encountered in samples collected in air masses arriving from northern Greece or the western coast of Turkey. Elevated concentrations of chlorine were found in samples with air masses either originating above the Atlantic Ocean and arriving at Finokalia via western Europe or recirculating over the western coast of the Black Sea.

  6. Attached and Unattached Activity Size Distribution of Short-Lived Radon Progeny (214Pb) and Evaluation of Deposition Fraction

    International Nuclear Information System (INIS)

    Mohamed, A.; Ahmed, A.A.; Ali, A.E.; Yuness, M.

    2009-01-01

    Inhalation of 2 '2 2 Rn progeny in the domestic environment contributes the greatest fraction of the natural radiation exposure to the public. Dosimetric models are most often used in the assessment of human lung doses due to inhaled radioactivity because of the difficulty in making direct measurements. These models require information about the parameters of activity size distributions of radon progeny. The current study presents measured data on the attached and unattached activity size distributions of radon progeny in indoor air in El-Minia, Egypt. The attached fraction was collected using a low pressure Berner cascade impactor technique. A screen diffusion battery was used for collecting the unattached fraction. Most of the attached activities for 222 Rn progeny were associated with aerosol particles of the accumulation mode. The mean activity median aerodynamic diameter (AMAD) of this mode for 21 4 P b was determined to be 401 nm with relative mean geometric standard deviation of 2.96. The mean value of specific air activity concentration of 214 Pb associated with that mode was determined to be 4.74 %0.44 Bq m -3 . The relative mean geometric standard deviations of unattached 214 Pb was determined to be 1.21 with the mean activity thermodynamic diameter (AMTD) of 1.2 nm. The mean unattached activity concentration of 214 Pb was found to be 0.44%0.14 Bq m-3. Based on the obtained results of radon progeny size distributions (unattached and attached), the deposition fractions in each airway generation of the human lung were evaluated by using a lung deposition model

  7. Nitrogen Fertilizer Replacement Value of Concentrated Liquid Fraction of Separated Pig Slurry Applied to Grassland

    NARCIS (Netherlands)

    Middelkoop, Van J.C.; Holshof, G.

    2017-01-01

    Seven grassland experiments on sandy and clay soils were performed during a period of 4 years to estimate the nitrogen (N) fertilizer replacement value (NFRV) of concentrated liquid fractions of separated pig slurry (mineral concentrate: MC). The risk of nitrate leaching when applying MC was

  8. Assessing SOC labile fractions through respiration test, density-size fractionation and thermal analysis - A comparison of methods

    Science.gov (United States)

    Soucemarianadin, Laure; Cécillon, Lauric; Chenu, Claire; Baudin, François; Nicolas, Manuel; Savignac, Florence; Barré, Pierre

    2017-04-01

    Soil organic matter (SOM) is the biggest terrestrial carbon reservoir, storing 3 to 4 times more carbon than the atmosphere. However, despite its major importance for climate regulation SOM dynamics remains insufficiently understood. For instance, there is still no widely accepted method to assess SOM lability. Soil respiration tests and particulate organic matter (POM) obtained by different fractionation schemes have been used for decades and are now considered as classical estimates of very labile and labile soil organic carbon (SOC), respectively. But the pertinence of these methods to characterize SOM turnover can be questioned. Moreover, they are very time-consuming and their reproducibility might be an issue. Alternate ways of determining the labile SOC component are thus well-needed. Thermal analyses have been used to characterize SOM among which Rock-Eval 6 (RE6) analysis of soil has shown promising results in the determination of SOM biogeochemical stability (Gregorich et al., 2015; Barré et al., 2016). Using a large set of samples of French forest soils representing contrasted pedoclimatic conditions, including deep samples (up to 1 m depth), we compared different techniques used for SOM lability assessment. We explored whether results from soil respiration test (10-week laboratory incubations), SOM size-density fractionation and RE6 thermal analysis were comparable and how they were correlated. A set of 222 (respiration test and RE6), 103 (SOM fractionation and RE6) and 93 (respiration test, SOM fractionation and RE6) forest soils samples were respectively analyzed and compared. The comparison of the three methods (n = 93) using a principal component analysis separated samples from the surface (0-10 cm) and deep (40-80 cm) layers, highlighting a clear effect of depth on the short-term persistence of SOC. A correlation analysis demonstrated that, for these samples, the two classical methods of labile SOC determination (respiration and SOM fractionation

  9. Determination of serum free thyroxine concentration (FT4) by means of fT4-fraction and total thyroxine concentration

    International Nuclear Information System (INIS)

    Passath, A.; Leb, G.

    1985-01-01

    A new equilibrium assay for the determination of serum free thyroxine was evaluated in 514 patients. The assay comprises a two-vial-procedure to measure total thyroxine and free thyroxine fraction by use of monoclonal antibodies. Free thyroxine concentrations are calculated from fT 4 -fraction and total thyroxine concentration readings. In euthyroidism the average free thyroxine fraction (%fT 4 ) was 0.011%, in hyperthyroidism this fraction was elevated, in hypothyroidism it was below normal. In patients with TBG anomalies, TBG values were inversely correlated with fT 4 fraction readings. The 'euthyroid reference range' of FT 4 (SPAC ET) was between 0.70 to 1.78ng/dl. This euthyroid range of FT 4 was determined from TT 4 concentrations measured by T 4 -RIA (SPAC T 4 MONO) which were 30% above TT 4 values measured by conventional T 4 -RIA (SPAC T 4 POLY; polyclonal antibodies). However, a different euthyroid range of FT 4 between 0.55 to 1.30 ng/dl was observed as well as by other investigators when conventional T 4 -RIA measurements were used for calculation of FT 4 values. Our results indicate that calculated FT 4 concentration values are highly dependent on the methods used for determination of total thyroxine concentrations. Precision and reproducability of this two vial equilibrium assay did not meet the requirements mandatory for the application as a clinical routine diagnostic procedure, and its general use for this purpose can as yet not be recommended. (Author)

  10. Ball mill tool for crushing coffee and cocoa beans base on fraction size sieving results

    Science.gov (United States)

    Haryanto, B.; Sirait, M.; Azalea, M.; Alvin; Cahyani, S. E.

    2018-02-01

    Crushing is one of the operation units that aimed to convert the size of solid material to be smoother particle’s size. The operation unit that can be used in this crushing is ball mill. The purpose of this study is to foresee the effect of raw material mass, grinding time, and the number of balls that are used in the ball mill tool related to the amount of raw material of coffee and cocoa beans. Solid material that has become smooth is then sieved with sieve mesh with size number: 50, 70, 100, and 140. It is in order to obtain the mass fraction that escaped from each sieve mesh. From the experiment, it can be concluded that mass percentage fraction of coffee powder is bigger than cocoa powder that escaped from the mesh. Hardness and humidity of coffee beans and cocoa beans have been the important factors that made coffee beans is easier to be crushed than cocoa beans.

  11. The Effect of Aggregate-Size Fractions on the Availability of Cu in Some Contaminated Soils with Heavy Metals

    Directory of Open Access Journals (Sweden)

    Akram Farshadirad

    2017-06-01

    Full Text Available Introduction: In recent years, because of the presence of industrial factories around the Isfahan province of Iran and high concentrations of heavy metals in the vicinity of them, and the gradual accumulation of heavy metals from various sources of pollution in urban areas over time, including gasoline combustion, and use of urban waste compost and sewage sludge as fertilizer, there has been widespread concerned regarding the human health problems with increasing heavy metals in soils around the Isfahan city. The variation of composition in the soil matrix may lead to variation of composition and behavior of soil heavy metals. Soil is a heterogeneous body of materials and soil components are obviously in interaction. Studies tacking this complexity often use aggregate measurements as surrogates of the complex soil matrix. So, it is important the understanding soil particle-size distribution of aggregates and its effects on heavy metal partitioning among the size fractions, the fate of metals and their toxicity potential in the soil environment. Therefore, the present study aimed to determine the Cu release potential from different size fractions of different polluted soils by different extractants and their availability for corn plant. Materials and Methods: Five soil samples were collected from the surface soils (0–15 cm of Isfahan province, in central of Iran. The soil samples were air-dried and ground to pass a 2-mm sieve for laboratory analysis. Air dried samples fractionated into four different aggregate size fractions 2.0–4.0 (large macro-aggregate, 0.25–2 (small macro-aggregate, 0.05–0.25 (micro-aggregate, and

  12. Measurement of void fraction and bubble size distribution in two-phase flow system

    International Nuclear Information System (INIS)

    Huahun, G.

    1987-01-01

    The importance of study two phase flow parameter and microstructure has appeared increasingly, with the development of two-phase flow discipline. In the paper, the measurement methods of several important microstructure parameter in a two phase flow vertical channel have been studied. Using conductance probe the two phase flow pattern and the average void fraction have been measured previously by the authors. This paper concerns microstructure of the bubble size distribution and local void fraction. The authors studied the methods of measuring bubble velocity, size distribution and local void fraction using double conductance probes and a set of apparatus. Based on our experiments and Yoshihiro work, a formula of calculated local void fraction has been deduced by using the statistical characteristics of bubbles in two phase flow and the relation between calculated bubble size and voltage has been determined. Finally the authors checked by using photograph and fast valve, which is classical but reliable. The results are the same with what has been studied before

  13. DISSOLVED ORGANIC-MATTER, CADMIUM, COPPER AND ZINC IN PIG SLURRY-SIZE AND SOIL SOLUTION-SIZE EXCLUSION CHROMATOGRAPHY FRACTIONS

    NARCIS (Netherlands)

    DELCASTILHO, P; DALENBERG, JW; BRUNT, K; BRUINS, AP

    1993-01-01

    Sephadex size exclusion chromatography was used to prepare molecular size fractions from liquid pig slurry, before and after aerobic interaction with a loamy-sand soil. In the liquid fractions organic matter was characterized and some components were identified. The distribution of zinc and copper

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

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Møldrup, Per; Tuller, Markus

    *-model) for 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 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 fractions...... (organic matter, clay, silt, fine and coarse sand), variably included in the model depending on the pF value. The volumetric content of a particular soil particle size fraction was included in the model if it was assumed to contribute to the pore size fraction still occupied with water at the given p...

  15. A method for detecting the presence of organic fraction in nucleation mode sized particles

    Directory of Open Access Journals (Sweden)

    P. Vaattovaara

    2005-01-01

    Full Text Available New particle formation and growth has a very important role in many climate processes. However, the overall knowlegde of the chemical composition of atmospheric nucleation mode (particle diameter, d<20 nm and the lower end of Aitken mode particles (d≤50 nm is still insufficient. In this work, we have applied the UFO-TDMA (ultrafine organic tandem differential mobility analyzer method to shed light on the presence of an organic fraction in the nucleation mode size class in different atmospheric environments. The basic principle of the organic fraction detection is based on our laboratory UFO-TDMA measurements with organic and inorganic compounds. Our laboratory measurements indicate that the usefulness of the UFO-TDMA in the field experiments would arise especially from the fact that atmospherically the most relevant inorganic compounds do not grow in subsaturated ethanol vapor, when particle size is 10 nm in diameter and saturation ratio is about 86% or below it. Furthermore, internally mixed particles composed of ammonium bisulfate and sulfuric acid with sulfuric acid mass fraction ≤33% show no growth at 85% saturation ratio. In contrast, 10 nm particles composed of various oxidized organic compounds of atmospheric relevance are able to grow in those conditions. These discoveries indicate that it is possible to detect the presence of organics in atmospheric nucleation mode sized particles using the UFO-TDMA method. In the future, the UFO-TDMA is expected to be an important aid to describe the composition of atmospheric newly-formed particles.

  16. Size-segregated concentration of heavy metals in an urban aerosol of the Balkans region (Belgrade

    Directory of Open Access Journals (Sweden)

    Đorđević D.

    2013-04-01

    Full Text Available This work focuses on the heavy metals contents of the size-segregated urban aerosol of the continental area of Balkans. The distribution of nano/micron heavy metals in the size-segregated urban aerosol of Belgrade center was studied during the summer–autumn of 2008. The particle size distribution in the size ranges Dp ≤ 0.49 μm, 0.49 ≤ Dp ≤ 0.95 μm, 0.95 ≤ Dp ≤ 1.5 μm, 1.5 ≤ Dp ≤ 3.0 μm, 3.0 ≤ Dp ≤ 7.2 μm and Dp ≥ 7.2 μm was measured. The aerosol samples were submitted to gravimetric and chemical analyses. The obtained mean mass concentration of the PM fractions was in accordance with an urban aerosol distribution. The aerosol mass concentrations were determined by gravimetric measurements (mGM and, for heavy metals analyzed by ICP/MS.

  17. Sampling and chemical analysis by TXRF of size-fractionated ambient aerosols and emissions

    International Nuclear Information System (INIS)

    John, A.C.; Kuhlbusch, T.A.J.; Fissan, H.; Schmidt, K.-G-; Schmidt, F.; Pfeffer, H.-U.; Gladtke, D.

    2000-01-01

    Results of recent epidemiological studies led to new European air quality standards which require the monitoring of particles with aerodynamic diameters ≤ 10 μm (PM 10) and ≤ 2.5 μm (PM 2.5) instead of TSP (total suspended particulate matter). As these ambient air limit values will be exceeded most likely at several locations in Europe, so-called 'action plans' have to be set up to reduce particle concentrations, which requires information about sources and processes of PMx aerosols. For chemical characterization of the aerosols, different samplers were used and total reflection x-ray fluorescence analysis (TXRF) was applied beside other methods (elemental and organic carbon analysis, ion chromatography, atomic absorption spectrometry). For TXRF analysis, a specially designed sampling unit was built where the particle size classes 10-2.5 μm and 2.5-1.0 μm were directly impacted on TXRF sample carriers. An electrostatic precipitator (ESP) was used as a back-up filter to collect particles <1 μm directly on a TXRF sample carrier. The sampling unit was calibrated in the laboratory and then used for field measurements to determine the elemental composition of the mentioned particle size fractions. One of the field campaigns was carried out at a measurement site in Duesseldorf, Germany, in November 1999. As the composition of the ambient aerosols may have been influenced by a large construction site directly in the vicinity of the station during the field campaign, not only the aerosol particles, but also construction material was sampled and analyzed by TXRF. As air quality is affected by natural and anthropogenic sources, the emissions of particles ≤ 10 μm and ≤ 2.5 μm, respectively, have to be determined to estimate their contributions to the so called coarse and fine particle modes of ambient air. Therefore, an in-stack particle sampling system was developed according to the new ambient air quality standards. This PM 10/PM 2.5 cascade impactor was

  18. Roundup Ready soybean gene concentrations in field soil aggregate size classes.

    Science.gov (United States)

    Levy-Booth, David J; Gulden, Robert H; Campbell, Rachel G; Powell, Jeff R; Klironomos, John N; Pauls, K Peter; Swanton, Clarence J; Trevors, Jack T; Dunfield, Kari E

    2009-02-01

    Roundup Ready (RR) soybeans containing recombinant Agrobacterium spp. CP4 5-enol-pyruvyl-shikimate-3-phosphate synthase (cp4 epsps) genes tolerant to the herbicide glyphosate are extensively grown worldwide. The concentration of recombinant DNA from RR soybeans in soil aggregates was studied due to the possibility of genetic transformation of soil bacteria. This study used real-time PCR to examine the concentration of cp4 epsps in four field soil aggregate size classes (>2000 microm, 2000-500 microm, 500-250 microm and 2000 mum fraction contained between 66.62% and 99.18% of total gene copies, although it only accounted for about 30.00% of the sampled soil. Aggregate formation may facilitate persistence of recombinant DNA.

  19. Unattached fraction and the aerosol size distribution of the radon progeny in a natural cave and mine atmospheres

    International Nuclear Information System (INIS)

    Butterweck, G.; Porstendoerfer, J.; Reineking, A.; Kesten, J.

    1992-01-01

    Measurements of the activity size distribution of aerosol-attached radon progeny and the amount of unattached radon daughters have been performed in mine atmospheres and a tourist cave. During working hours a large number (10 5 -10 6 cm -3 ) of aerosol particles is generated in mines, mainly by diesel engines. The activity size distribution of these aerosol particles has smaller median diameters (AMAD about 200 nm) than the aged aerosol existing in the mine during non-working hours (AMAD about 350 nm). Strictly correlated to the aerosol concentration, the unattached fraction of the radon progeny, f p , in the tourist cave (3000 particles per cm 3 ) is higher (f p = 0.1) than in mines (f p 0.01) during working hours. This yields 1.4-2.5 times higher radiation dose conversion factors in the natural cave than in mines under working conditions. (author)

  20. [The pharmaceutical market in Mexico: size, value, and concentration].

    Science.gov (United States)

    Torres Guerra, Sandra; Gutiérrez, Juan Pablo

    2009-07-01

    To describe the pharmaceutical drug market in Mexico in terms of its size, structure, business' market power, and consumer negotiating power. A descriptive study based on data from the 2004 Economics Census and the reports of IMS Health, Inc. (Norwalk, Connecticut, United States of America). Sales amounts and volumes of Mexico's pharmaceutical companies from 2002-2005 were obtained and the Herfindahl-Hirschman Index (HHI) and its inverse were calculated as indicators of the market's degree of concentration; also, price elasticity was determined by a product index. The total value of the products manufactured by the pharmaceutical sector was 115 billion in 2006 Mexican pesos, of which 99% pertained to companies categorized as large. This amount constituted 1.2% of the national gross domestic product that year (20.0% of the health sector's portion, estimated to be 6.0%) and 3.9% of the total value of manufactured goods. The HHI of Mexico's pharmaceutical market during the study period was about 0.04, albeit with a steady decline, and its inverse decreased from 23 to 26. The price elasticity of pharmaceutical products was minimal (0.007, 0.003, and -0.002). This study constitutes a preliminary description of Mexico's pharmaceutical market, one of the country's most dynamic economic sectors. It confirmed that the market is a rigid oligopoly, and thus supports enactment of firmer regulatory tools to reduce the power of the manufacturers in favor of that of the consumers.

  1. Comparison of layer grain size analysis with pipette and sieve analysis: a solution for the underestimation of the clay fraction

    NARCIS (Netherlands)

    Konert, M.; Vandenberghe, J.F.

    1997-01-01

    Classically, the grain size of soil and sediment samples is determined by the sieve method for the coarse fractions and by the pipette method, based on the 'Stokes' sedimentation rates, for the fine fractions. Results from the two methods are compared with results from laser diffraction size

  2. Relationship between processing score and kernel-fraction particle size in whole-plant corn silage.

    Science.gov (United States)

    Dias Junior, G S; Ferraretto, L F; Salvati, G G S; de Resende, L C; Hoffman, P C; Pereira, M N; Shaver, R D

    2016-04-01

    Kernel processing increases starch digestibility in whole-plant corn silage (WPCS). Corn silage processing score (CSPS), the percentage of starch passing through a 4.75-mm sieve, is widely used to assess degree of kernel breakage in WPCS. However, the geometric mean particle size (GMPS) of the kernel-fraction that passes through the 4.75-mm sieve has not been well described. Therefore, the objectives of this study were (1) to evaluate particle size distribution and digestibility of kernels cut in varied particle sizes; (2) to propose a method to measure GMPS in WPCS kernels; and (3) to evaluate the relationship between CSPS and GMPS of the kernel fraction in WPCS. Composite samples of unfermented, dried kernels from 110 corn hybrids commonly used for silage production were kept whole (WH) or manually cut in 2, 4, 8, 16, 32 or 64 pieces (2P, 4P, 8P, 16P, 32P, and 64P, respectively). Dry sieving to determine GMPS, surface area, and particle size distribution using 9 sieves with nominal square apertures of 9.50, 6.70, 4.75, 3.35, 2.36, 1.70, 1.18, and 0.59 mm and pan, as well as ruminal in situ dry matter (DM) digestibilities were performed for each kernel particle number treatment. Incubation times were 0, 3, 6, 12, and 24 h. The ruminal in situ DM disappearance of unfermented kernels increased with the reduction in particle size of corn kernels. Kernels kept whole had the lowest ruminal DM disappearance for all time points with maximum DM disappearance of 6.9% at 24 h and the greatest disappearance was observed for 64P, followed by 32P and 16P. Samples of WPCS (n=80) from 3 studies representing varied theoretical length of cut settings and processor types and settings were also evaluated. Each WPCS sample was divided in 2 and then dried at 60 °C for 48 h. The CSPS was determined in duplicate on 1 of the split samples, whereas on the other split sample the kernel and stover fractions were separated using a hydrodynamic separation procedure. After separation, the

  3. Carbon Storage in Soil Size Fractions Under Two Cacao Agroforestry Systems in Bahia, Brazil

    Science.gov (United States)

    Gama-Rodrigues, Emanuela F.; Ramachandran Nair, P. K.; Nair, Vimala D.; Gama-Rodrigues, Antonio C.; Baligar, Virupax C.; Machado, Regina C. R.

    2010-02-01

    Shaded perennial agroforestry systems contain relatively high quantities of soil carbon (C) resulting from continuous deposition of plant residues; however, the extent to which the C is sequestered in soil will depend on the extent of physical protection of soil organic C (SOC). The main objective of this study was to characterize SOC storage in relation to soil fraction-size classes in cacao ( Theobroma cacao L.) agroforestry systems (AFSs). Two shaded cacao systems and an adjacent natural forest in reddish-yellow Oxisols in Bahia, Brazil were selected. Soil samples were collected from four depth classes to 1 m depth and separated by wet-sieving into three fraction-size classes (>250 μm, 250-53 μm, and cacao AFSs, the C contained in the macroaggregate fraction might become stabilized in the soil. The study shows the role of cacao AFSs in mitigating greenhouse gas (GHG) emission through accumulation and retention of high amounts of organic C in the soils and suggests the potential benefit of this environmental service to the nearly 6 million cacao farmers worldwide.

  4. Separation of Yttrium from Rare Earth Concentrates in Fractional Hydroxide Precipitation

    International Nuclear Information System (INIS)

    Tri Handini; Purwoto; Mulyono

    2007-01-01

    Yttrium has been separated from rare earth concentrates by precipitation in fractional hydroxide using urea. The purpose of this research is to increase the yttrium rate resulting from the sedimentary process through separation of yttrium from other rare earth in fractional hydroxide precipitation using urea. In this research, we study the process variable of the concentration of urea, the ratio of feed volume to condensation volume of urea, as well as the temperature. Determination analysis of the rare earth rate is conducted using an X-ray spectrometer. The best result Y=92.89 % is obtained at a concentration of urea of 50 %, a level of precipitation of 3 times, and a temperature of 80°C. (author)

  5. Heavy Metal and PAH Concentrations in Highway Runoff Deposits Fractionated on Settling Velocities

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben

    2009-01-01

    The correlation between settling velocity and associated pollutant concentrations is of major importance for best management practice in designing, redesigning, or evaluation of the efficiency of existing pond facilities for retaining unwanted pollutants. The prospect of this note is to state...... the relationship between the settling velocity of the runoff particles and the corresponding metal and polyaromatic hydrocarbon (PAH) concentration directly instead of dealing with two unknowns-the density and the shape of a single particle fraction in a settling velocity calculations. The measurements show...... and copper and there is no significant correlation between PAH concentration and settling velocity. The largest mass of metals and PAH within each pond can be found on the particle fraction with a settling velocity of 5.5-2.5 mm/s....

  6. Investigation of size-fractionated urban aerosol and trace gases in Budapest by nuclear-related and other analytical techniques

    International Nuclear Information System (INIS)

    Salma, I.; Maenhaut, W.; Zemplen-Papp, E.; Bobvos, J.

    1998-01-01

    An air pollution study was conducted at two urban residential sites in Budapest (one representing the downtown, the other representing a wooded suburb) from 9 April till 17 May 1996. Size-fractionated aerosol samples were simultaneously collected on a daily basis, and meteorological conditions were recorded at both sampling sites. Stacked filter units (SFUs) with an upper size inlet cut-off were used as sampling device separating the urban aerosol into a coarse (about 10-2 μm equivalent aerodynamic diameter, EAD) and a fine ( 2 , SO 2 , CO and the total mass of the suspended particulate matter were measured every half hour at one of the sampling sites by commercial equipment. The SFU filters were analyzed by gravimetry for the total particle mass, by a light reflectance technique for black carbon, by particle-induced X-ray emission analysis and instrumental neutron activation analysis for elemental composition (in combination for up to 40-45 elements). The analytical results were used for characterizing the levels and the multi-elemental composition of the urban aerosol at both sampling sites and for both size fractions, for investigating the atmospheric concentrations and diurnal variation of some criteria pollutants, and for comparing the time-trends of aerosols and trace gases. Identification of the major source types of the aerosol fractions and trace gases, and assessment of the relative contribution from these sources are to be accomplished by multivariate receptor modeling. The present paper reports on the status of the air pollution study, and gives a discussion of the results

  7. Optimization of protein fractionation by skim milk microfiltration: Choice of ceramic membrane pore size and filtration temperature.

    Science.gov (United States)

    Jørgensen, Camilla Elise; Abrahamsen, Roger K; Rukke, Elling-Olav; Johansen, Anne-Grethe; Schüller, Reidar B; Skeie, Siv B

    2016-08-01

    The objective of this study was to investigate how ceramic membrane pore size and filtration temperature influence the protein fractionation of skim milk by cross flow microfiltration (MF). Microfiltration was performed at a uniform transmembrane pressure with constant permeate flux to a volume concentration factor of 2.5. Three different membrane pore sizes, 0.05, 0.10, and 0.20µm, were used at a filtration temperature of 50°C. Furthermore, at pore size 0.10µm, 2 different filtration temperatures were investigated: 50 and 60°C. The transmission of proteins increased with increasing pore size, giving the permeate from MF with the 0.20-µm membrane a significantly higher concentration of native whey proteins compared with the permeates from the 0.05- and 0.10-µm membranes (0.50, 0.24, and 0.39%, respectively). Significant amounts of caseins permeated the 0.20-µm membrane (1.4%), giving a permeate with a whitish appearance and a casein distribution (αS2-CN: αS1-CN: κ-CN: β-CN) similar to that of skim milk. The 0.05- and 0.10-µm membranes were able to retain all caseins (only negligible amounts were detected). A permeate free from casein is beneficial in the production of native whey protein concentrates and in applications where transparency is an important functional characteristic. Microfiltration of skim milk at 50°C with the 0.10-µm membrane resulted in a permeate containing significantly more native whey proteins than the permeate from MF at 60°C. The more rapid increase in transmembrane pressure and the significantly lower concentration of caseins in the retentate at 60°C indicated that a higher concentration of caseins deposited on the membrane, and consequently reduced the native whey protein transmission. Optimal protein fractionation of skim milk into a casein-rich retentate and a permeate with native whey proteins were obtained by 0.10-µm MF at 50°C. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All

  8. Concentration of 17 Elements in Subcellular Fractions of Beef Heart Tissue Determined by Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wester, P O

    1964-12-15

    Subcellular fractions of beef heart tissue are investigated, by means of neutron activation analysis, with respect to their concentration of 17 different elements. A recently developed ion-exchange technique combined with gamma spectrometry is used. The homogeneity of the subcellular fractions is examined electron microscopically. The following elements are determined: As, Ba, Br, Cas Co, Cs, Cu, Fe, Hg, La, Mo, P, Rb, Se, Sm, W and Zn. The determination of Ag, Au, Cd, Ce, Cr, Sb and Sc is omitted, in view of contamination. Reproducible and characteristic patterns of distribution are obtained for all elements studied.

  9. Concentration of 17 Elements in Subcellular Fractions of Beef Heart Tissue Determined by Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Wester, P.O.

    1964-12-01

    Subcellular fractions of beef heart tissue are investigated, by means of neutron activation analysis, with respect to their concentration of 17 different elements. A recently developed ion-exchange technique combined with gamma spectrometry is used. The homogeneity of the subcellular fractions is examined electron microscopically. The following elements are determined: As, Ba, Br, Cas Co, Cs, Cu, Fe, Hg, La, Mo, P, Rb, Se, Sm, W and Zn. The determination of Ag, Au, Cd, Ce, Cr, Sb and Sc is omitted, in view of contamination. Reproducible and characteristic patterns of distribution are obtained for all elements studied

  10. Rare-earths in size fractions and sedimentary rocks of Pennsylvanian-Permian age from the mid-continent of the U.S.A

    International Nuclear Information System (INIS)

    Cullers, R.; Chaudhuri, S.; Kilbane, N.; Koch, R.

    1979-01-01

    The REE (rare-earth) contents of sixty-three <2μ fractions of Pennsylvanian and Permian platform sediment from the mid-continent of the U.S.A. vary considerably (ΣREE = 46 to 439 ppm: La/Lu = 5.2 to 15.7; correlation coefficient of REE with La Lu = 0.89), but the Eu/Sm ratios are nearly constant even in reducing environments that concentrate U (0.16 to 0.22). There is no correlation of REE content to clay mineralogy. Lower Permian <2μ fractions from continental to nearshore marine sediment in Oklahoma have higher REE content (244 to 261 ppm) than marine facies in Kansas (46 to 140 ppm) but <2μ Upper Permian fractions in an evaporite basin have constant but high REE content (288 to 281 ppm; one = 153 ppm). All Pennsylvanian <2μ fractions from Oklahoma have high REE content (209 to 439 ppm), and fractions from Kansas cyclothems have variable REE content (86 to 438 ppm). REE content in the <2μ fractions is inherited from the provenance, but is modified by ion exchange during weathering, transportation or deposition. Exchangable REE tend to be concentrated in clay minerals in basic environments, but removed in acid environments. Sand and gravel-size fractions consist mostly of quartz or chert so their REE content is low (7.9 to 40.6 ppm) although heavy minerals may contribute a large fraction of the REE content. Unexpectedly silt-size fractions have REE contents (74 to 355 ppm) that are usually lower but similar to their <2μ fractions, and the REE contents do not correlate to clay mineral/quartz ratios. (author)

  11. Mineralization of organic phosphorus in soil size fractions under different vegetation covers in the north of Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Joice Cleide de Oliveira Rita

    2013-10-01

    Full Text Available In unfertilized, highly weathered tropical soils, phosphorus (P availability to plants is dependent on the mineralization of organic P (Po compounds. The objective of this study was to estimate the mineralization of total and labile Po in soil size fractions of > 2.0, 2.0-0.25 and 2.0 and 2.0-0.25 mm fractions, respectively. In contrast, there was an average increase of 90 % of total Po in microaggregates of 2.0 (-50 % and < 0.25 mm (-76 % fractions, but labile Po increased by 35 % in the 2.0-0.25 mm fraction. The Po fraction relative to total extracted P and total labile P within the soil size fractions varied with the vegetation cover and incubation time. Therefore, the distribution of P fractions (Pi and Po in the soil size fraction revealed the distinctive ability of the cover species to recycle soil P. Consequently, the potential of Po mineralization varied with the size fraction and vegetation cover. Because Po accounted for most of the total labile P, the P availability to plants was closely related to the mineralization of this P fraction.

  12. Neutral hydrolysable sugars, OC and N content across soil aggregate size fractions, as an effect of two different crop rotations

    Science.gov (United States)

    Angeletti, Carlo; Giannetta, Beatrice; Kölbl, Angelika; Monaci, Elga; Kögel-Knabner, Ingrid; Vischetti, Costantino

    2016-04-01

    This paper presents the results regarding the effects of two 13 years long crop rotations, on the composition of mineral associated neutral sugars, organic carbon (OC) and N concentration, across different aggregate size fractions. The two cropping sequences were characterized by different levels of N input from plant residues and tillage frequency. We also analysed the changes that occurred in soil organic matter (SOM) chemical composition following the cultivation in the two soils of winter wheat and chickpea on the same soils. The analysis of OC and N content across soil aggregate fractions allowed getting an insight into the role played by SOM chemical composition in the formation of organo-mineral associations, while neutral sugars composition provided information on mineral associated SOM origin and decomposition processes, as pentoses derive mostly from plant tissues and hexoses are prevalently of microbial origin. Soil samples were collected from two adjacent fields, from the 0-10 cm layer, in November 2011 (T0). For 13 years before the beginning of the experiment, one soil was cultivated mostly with alfalfa (ALF), while a conventional cereal-sunflower-legume rotation (CON) was carried out on the other. Winter wheat and chickpea were sown on the two soils during the following 2 growing seasons and the sampling was repeated after 18 months (T1). A combination of aggregates size and density fractionation was used to isolate OM associated with mineral particles in: macro-aggregates (>212 μm), micro-aggregates ( 63 μm) and silt and clay size particles (carbohydrates contributions in every other fraction. GM/AX varied slightly between the soils. In conclusion, the crop rotation determined the accumulation of different levels of SOM in the two soils. The 18-months cultivation experiment determined an increase in the tillage intensity in ALF, and the introduction of N rich chickpea residues in CON. Consequently SOM chemical composition responded divergently in

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  14. Bacterial Preferences for Specific Soil Particle Size Fractions Revealed by Community Analyses

    DEFF Research Database (Denmark)

    Hemkemeyer, Michael; Dohrmann, Anja B.; Christensen, Bent Tolstrup

    2018-01-01

    Genetic fingerprinting demonstrated in previous studies that differently sized soil particle fractions (PSFs; clay, silt, and sand with particulate organic matter (POM)) harbor microbial communities that differ in structure, functional potentials and sensitivity to environmental conditions....... To elucidate whether specific bacterial or archaeal taxa exhibit preference for specific PSFs, we examined the diversity of PCR-amplified 16S rRNA genes by high-throughput sequencing using total DNA extracted from three long-term fertilization variants (unfertilized, fertilized with minerals, and fertilized...

  15. Fractionated breath condensate sampling: H2O2 concentrations of the alveolar fraction may be related to asthma control in children

    Directory of Open Access Journals (Sweden)

    Trischler Jordis

    2012-02-01

    Full Text Available Abstract Background Asthma is a chronic inflammatory disease of the airways but recent studies have shown that alveoli are also subject to pathophysiological changes. This study was undertaken to compare hydrogen peroxide (H2O2 concentrations in different parts of the lung using a new technique of fractioned breath condensate sampling. Methods In 52 children (9-17 years, 32 asthmatic patients, 20 controls measurements of exhaled nitric oxide (FENO, lung function, H2O2 in exhaled breath condensate (EBC and the asthma control test (ACT were performed. Exhaled breath condensate was collected in two different fractions, representing mainly either the airways or the alveoli. H2O2 was analysed in the airway and alveolar fractions and compared to clinical parameters. Results The exhaled H2O2 concentration was significantly higher in the airway fraction than in the alveolar fraction comparing each single pair (p = 0.003, 0.032 and 0.040 for the whole study group, the asthmatic group and the control group, respectively. Asthma control, measured by the asthma control test (ACT, correlated significantly with the H2O2 concentrations in the alveolar fraction (r = 0.606, p = 0.004 but not with those in the airway fraction in the group of children above 12 years. FENO values and lung function parameters did not correlate to the H2O2 concentrations of each fraction. Conclusion The new technique of fractionated H2O2 measurement may differentiate H2O2 concentrations in different parts of the lung in asthmatic and control children. H2O2 concentrations of the alveolar fraction may be related to the asthma control test in children.

  16. Levels and Speciation of Platinum in Size-Fractionated Atmospheric Aerosol in Urban and Rural Sites across Europe

    Science.gov (United States)

    Shafer, Martin; Antkiewicz, Dagmara; Overdier, Joel; Schauer, James

    2016-04-01

    In this study we characterized the levels and speciation of platinum in a unique set of size-resolved atmospheric aerosol (PM) samples obtained from urban environments across Europe. From April-July 2012 we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities (Amsterdam, Frankfurt, London, Milan, Stockholm, and Thessaloniki). A Hi-Vol sampler was used to collect PM in three size classes (>PM7, PM7-PM3, PM3) and characterized for total platinum, soluble platinum (in a suite of physiologically relevant fluids - lung fluid (ALF), Gambles saline, 0.07M HCl, and MQ) and speciated forms (colloidal and anionic) within the soluble fractions. In addition we measured 50 other elements by SF-ICPMS, soluble ions by IC, and soluble organic carbon in the PM. Order-of-magnitude differences in air concentrations of total platinum were observed between urban sites, ranging from 4 to over 45 pg/m3; with a median level of 6 pg/m3. When platinum concentrations are normalized to PM mass the cross Europe and site-to-site variability was substantially reduced - a 3-fold variation from 200 to 600 ng/g was observed. Roadside canyon sites in London, Stockholm and Thessaloniki exhibited the highest concentrations; however levels at urban background sites were remarkably similar across the cities. Relatively consistent and low concentrations (1 to 2 pg/m3) of total platinum were observed at rural background sites across Europe. The contribution of coarse particles (>7 micron and 7-3 micron) to air concentrations of total platinum was very significant (>35% at nearly all sites). Soluble platinum fractions ranged from 2 to 6% (MQ to HCl) in rural background sites to 5 to 20% (MQ to HCl) in roadway canyon sites in London and Thessaloniki; with the extractable platinum fractions a strong function of pH. With the exception of urban canyon sites in London and Thessaloniki, soluble platinum concentrations in the fine aerosol (PM3) were all

  17. 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.

  18. Fluorescence of soil humic acids and their fractions obtained by tandem size exclusion chromatography-polyacrylamide gel electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Trubetskaya, O. [Russian Academy of Sciences, Moscow Region (Russian Federation). Shemyakin and Ovchinnikov Inst. of Bioorganic Chemistry; Trubetskoj, O. [Russian Academy of Sciences, Moscow Region (Russian Federation). Inst. of Basic Biological Problems; Guyot, G.; Richard, C. [UMR CNRS 6505, Aubiere (France). Lab. de Photochimie Moleculaire et Macromoleculaire; Andreux, F. [Centre des Sciences de la Terre, Dijon (France)

    2002-07-01

    Humic acids (HAs) extracted from soils of different origin (chernozem, ferralsol and ranker) and their fractions (A, B and C+D) obtained by tandem size exclusion chromatography-polyacrylamide gel electrophoresis were investigated by steady-state fluorescence spectroscopy in the emission mode. Independently of HA source, high molecular size fractions A and B are shown to be weakly fluorescent. The main fluorophores, especially those emitting at long wavelength (around 500-510 nm), are contained in the polar and low molecular size fractions C+D. As indicated by the observed pH effect, aromatic structures bearing carboxylate and OH substituents may be involved in these longer wavelength emissions. [author].

  19. Particle size distributions, size concentration relationships, and adherence to hands of selected geologic media derived from mining, smelting, and quarrying activities

    Energy Technology Data Exchange (ETDEWEB)

    Bergstrom, Carolyn; Shirai, Jeffry; Kissel, John, E-mail: jkissel@uw.edu

    2011-09-15

    Hand-to-mouth activity, especially in children, is a potentially significant pathway of exposure to soil contaminants. Hand-mouthing behavior is of particular concern in areas impacted by mining, smelting, and quarrying activities as these activities may lead to elevated levels of heavy metals in soil. In order to estimate potential exposures to contaminated geologic media attributable to hand-to-mouth contact, it is useful to characterize adherence of those media to skin, as contaminant concentrations in adhered media may differ greatly from unfractionated, whole media concentrations. Such an investigation has been undertaken to aid estimation of exposures to arsenic, cadmium, lead, and zinc in nine different geologic media collected in the Pacific Northwest region of the United States. After establishing the particle size distribution of each medium (fractions < 63 {mu}m, 63-150 {mu}m, 150-250 {mu}m, and 250 {mu}m-2 mm were determined) and target elemental concentrations within each particle size fraction, an active handling protocol involving six volunteers was conducted. Wet media always adhered to a greater extent than dry media and adhered media generally had higher elemental concentrations than bulk media. Regression analyses suggest smaller particle fractions may have higher elemental concentrations. Results of application of a maximum likelihood estimation technique generally indicate that handling of dry media leads to preferential adherence of smaller particle sizes, while handling of wet media does not. Because adhered material can differ greatly in particle size distribution from that found in bulk material, use of bulk concentrations in exposure calculations may lead to poor estimation of actual exposures. Since lead has historically been a metal of particular concern, EPA's Integrated Exposure Uptake Biokinetic (IEUBK) Model was used to examine the potential consequences of evaluating ingestion of the selected media assuming concentrations in

  20. Effects of trace element concentration on enzyme controlled stable isotope fractionation during aerobic biodegradation of toluene.

    Science.gov (United States)

    Mancini, Silvia A; Hirschorn, Sarah K; Elsner, Martin; Lacrampe-Couloume, Georges; Sleep, Brent E; Edwards, Elizabeth A; Lollar, Barbara Sherwood

    2006-12-15

    The effects of iron concentration on carbon and hydrogen isotopic fractionation during aerobic biodegradation of toluene by Pseudomonas putida mt-2 were investigated using a low iron medium and two different high iron media. Mean carbon enrichment factors (epsilonc) determined using a Rayleigh isotopic model were smaller in culture grown under high iron conditions (epsilonc = -1.7+/-0.1%) compared to low iron conditions (epsilonc = -2.5+/-0.3%). Mean hydrogen enrichment factors (epsilonH) were also significantly smaller for culture grown under high iron conditions (epsilonH = -77 +/-4%) versus low iron conditions (EpsilonH = -159+/-11%). A mechanistic model for enzyme kinetics was used to relate differences in the magnitude of isotopic fractionation for low iron versus high iron cultures to the efficiency of the enzymatic transformation. The increase of carbon and hydrogen enrichment factors at low iron concentrations suggests a slower enzyme-catalyzed substrate conversion step (k2) relative to the enzyme-substrate binding step (k-l) at low iron concentration. While the observed differences were subtle and, hence, do not significantly impact the ability to use stable isotope analysis in the field, these results demonstrated that resolvable differences in carbon and hydrogen isotopic fractionation were related to low and high iron conditions. This novel result highlights the need to further investigate the effects of other trace elements known to be key components of biodegradative enzymes.

  1. Input related microbial carbon dynamic of soil organic matter in particle size fractions

    Science.gov (United States)

    Gude, A.; Kandeler, E.; Gleixner, G.

    2012-04-01

    This paper investigated the flow of carbon into different groups of soil microorganisms isolated from different particle size fractions. Two agricultural sites of contrasting organic matter input were compared. Both soils had been submitted to vegetation change from C3 (Rye/Wheat) to C4 (Maize) plants, 25 and 45 years ago. Soil carbon was separated into one fast-degrading particulate organic matter fraction (POM) and one slow-degrading organo-mineral fraction (OMF). The structure of the soil microbial community were investigated using phospholipid fatty acids (PLFA), and turnover of single PLFAs was calculated from the changes in their 13C content. Soil enzyme activities involved in the degradation of carbohydrates was determined using fluorogenic MUF (methyl-umbelliferryl phosphate) substrates. We found that fresh organic matter input drives soil organic matter dynamic. Higher annual input of fresh organic matter resulted in a higher amount of fungal biomass in the POM-fraction and shorter mean residence times. Fungal activity therefore seems essential for the decomposition and incorporation of organic matter input into the soil. As a consequence, limited litter input changed especially the fungal community favouring arbuscular mycorrhizal fungi. Altogether, supply and availability of fresh plant carbon changed the distribution of microbial biomass, the microbial community structure and enzyme activities and resulted in different priming of soil organic matter. Most interestingly we found that only at low input the OMF fraction had significantly higher calculated MRT for Gram-positive and Gram-negative bacteria suggesting high recycling of soil carbon or the use of other carbon sources. But on average all microbial groups had nearly similar carbon uptake rates in all fractions and both soils, which contrasted the turnover times of bulk carbon. Hereby the microbial carbon turnover was always faster than the soil organic carbon turnover and higher carbon input

  2. Carbon storage of different soil-size fractions in Florida silvopastoral systems.

    Science.gov (United States)

    Haile, Solomon G; Nair, P K Ramachandran; Nair, Vimala D

    2008-01-01

    Compared with open (treeless) pasture systems, silvopastoral agroforestry systems that integrate trees into pasture production systems are likely to enhance soil carbon (C) sequestration in deeper soil layers. To test this hypothesis, total soil C contents at six soil depths (0-5, 5-15, 15-30, 30-50, 50-75, and 75-125 cm) were determined in silvopastoral systems with slash pine (Pinus elliottii) + bahiagrass (Paspalum notatum) and an adjacent open pasture (OP) with bahiagrass at four sites, representing Spodosols and Ultisols, in Florida. Soil samples from each layer were fractionated into three classes (250-2000, 53-250, and <53 microm), and the C contents in each were determined. Averaged across four sites and all depths, the total soil organic carbon (SOC) content was higher by 33% in silvopastures near trees (SP-T) and by 28% in the alleys between tree rows (SP-A) than in adjacent open pastures. It was higher by 39% in SP-A and 20% in SP-T than in open pastures in the largest fraction size (250-2000 microm) and by 12.3 and 18.8%, respectively, in the intermediate size fraction (53-250 microm). The highest SOC increase (up to 45 kg m(-2)) in whole soil of silvopasture compared with OP was at the 75- to 125-cm depth at the Spodosol sites. The results support the hypothesis that, compared with open pastures, silvopastures contain more C in deeper soil layers under similar ecological settings, possibly as a consequence of a major input to soil organic matter from decomposition of dead tree-roots.

  3. Toxicologically important trace elements and organic compounds investigated in size-fractionated urban particulate matter collected near the Prague highway

    International Nuclear Information System (INIS)

    Sysalová, Jiřina; Sýkorová, Ivana; Havelcová, Martina; Száková, Jiřina; Trejtnarová, Hana; Kotlík, Bohumil

    2012-01-01

    Urban particulate matter was collected in the most exposed area of Prague, near a busy highway, in order to provide petrographic and chemical characterization useful for health impact assessment in that locality or other applications. Samples were collected from filters of the air conditioning system in two years, 2009 and 2010, and sieved into four grain-size fractions: 0.507–0.119 mm, 0.119–0.063 mm, 3 extracted solutions. A composition of inorganic and carbonaceous particles of natural and anthropogenic origin and their morphology were studied by optical and electron microscopy. Organic solvent extracts of the samples were analyzed using gas chromatography to compare the organic compound distribution in fractions. Only slight differences between 2009 and 2010 years are visible. The relatively high extractable part of most investigated elements confirms mobility and potential availability to organisms. The changes can be recognized in the petrographic and organic composition in samples from both years, which were likely the result of various inputs of source materials. Specific organic marker compounds indicate contribution from fossil fuels, plant materials and bacteria. -- Highlights: ► Uncommon urban particulate matter collected near the highway in years 2009 and 2010 was deeply characterized. ► Harmful organic compounds and toxic analytes were tested in grain-size fractions and completed with electron microscopy studies. ► Very similar concentration levels were found in elemental composition in samples from two years. ► Petrographic and organic compositions were different in both samples. ► Relatively high mobility of selected analytes was found in 2M HNO 3 extracted solutions.

  4. Estimate of serum immunoglobulin G concentration using refractometry with or without caprylic acid fractionation.

    Science.gov (United States)

    Morrill, K M; Polo, J; Lago, A; Campbell, J; Quigley, J; Tyler, H

    2013-07-01

    Objectives of this study were to develop a rapid calf-side test to determine serum IgG concentrations using caprylic acid (CA) fractionation, followed by refractometry of the IgG-rich supernatant and compare the accuracy of this method with results obtained using refractometry using raw serum. Serum samples (n=200) were obtained from 1-d-old calves, frozen (-20°C), and shipped to the laboratory. Samples were allowed to thaw for 1h at room temperature. Fractionation with CA was conducted by adding 1mL of serum to a tube containing 45, 60, or 75µL of CA and 0.5, 1.0, or 1.5mL of 0.06 M acetic acid. The tube contents were mixed well, allowed to react for 1 min, and then centrifuged at 3,300 × g for 0, 10, or 20 min at 25°C. The %Brix and refractive index of the fractionated supernatant were determined using a digital refractometer. Nonfractionated serum was analyzed for %Brix (BRn), refractive index (nDn), and IgG concentration by radial immunodiffusion. The mean serum IgG concentration was 19.0 mg/mL [standard deviation (SD)=9.7], with a range of 3.5 to 47.0 mg/mL. The mean serum BRn was 8.6 (SD=0.91), with a range of 6.8 to 11.0. The mean serum nDn was 1.34566 (SD=0.00140), with a range of 1.34300 to 1.34930. Serum nDn was positively correlated with IgG concentration (correlation coefficient=0.86; n=185). Fractionated samples treated with 1mL 0.6 M acetic acid and 60µL of CA and not centrifuged before analysis resulted in a strong relationship between the refractive index of the fractionated supernatant and IgG (correlation coefficient=0.80; n=45). Regression was used to determine cut points indicative of 10, 12, and 14 mg of IgG/mL to determine the sensitivity and specificity of refractometry to identify failure of passive transfer (serum IgG refractometry of nonfractionated calf serum provides a strong estimate of IgG concentration and 7.8% Brix may be used as the cut point to identify failure of passive transfer in 1-d-old calves. Copyright © 2013 American

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-09-15

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

  6. Estimate of colostral immunoglobulin G concentration using refractometry without or with caprylic acid fractionation.

    Science.gov (United States)

    Morrill, K M; Conrad, E; Polo, J; Lago, A; Campbell, J; Quigley, J; Tyler, H

    2012-07-01

    Our objectives were to evaluate the use of refractometry as a means of estimating immunoglobulin G (IgG) concentration of bovine maternal colostrum (MC) and determine if fractionation of MC using caprylic acid (CA) improved estimates of IgG. Samples (n=85) of MC were collected from a single dairy in California and used to determine the method of CA fraction that produced the best prediction of IgG based on CA fractionation followed by refractometry. Subsequently, samples of MC (n=827) were collected from 67 farms in 12 states to compare refractometry with or without CA fractionation as methods to estimate IgG concentration. Samples were collected from the feeding pool and consisted of fresh (n=196), previously frozen (n=479), or refrigerated (n=152) MC. Samples were further classified by the number freeze-thaw cycles before analysis. Fractionation with CA was conducted by adding 1 mL of MC to a tube containing 75 μL of CA and 1 mL of 0.06 M acetic acid. The tube was shaken and allowed to react for 1 min. Refractive index of the IgG-rich supernatant (nDf) was determined using a digital refractometer. Whole, nonfractionated MC was analyzed for IgG by radial immunodiffusion (RID) and refractive index (nDw). The relationship between nDf and IgG (r=0.53; n=805) was weak, whereas that between nDw and IgG was stronger (r=0.73; n=823). Fresh samples analyzed by refractometry that subsequently went through 1 freeze-thaw cycle before RID analysis resulted in the strongest relationship between IgG and nDf or nDw (r=0.93 and 0.90, respectively). The MC samples collected fresh on the farm but frozen 2 or more times before analysis by refractometry or RID had low correlations between IgG and nDf and nDw (r=0.09 and 0.01). Samples refrigerated or frozen on the farm before analysis had weaker relationships between RID and nDf or nDw (r=0.38 to 0.80), regardless of the number of freeze-thaw cycles. Breed and lactation number did not affect the accuracy of either test. These

  7. Size-fractionated dissolved primary production and carbohydrate composition of the coccolithophore Emiliania huxleyi

    Science.gov (United States)

    Borchard, C.; Engel, A.

    2015-02-01

    Extracellular release (ER) by phytoplankton is the major source of fresh dissolved organic carbon (DOC) in marine ecosystems and accompanies primary production during all growth phases. Little is known, so far, on size and composition of released molecules, and to which extent ER occurs passively, by leakage, or actively, by exudation. Here, we report on ER by the widespread and bloom-forming coccolithophore Emiliania huxleyi grown under steady-state conditions in phosphorus-controlled chemostats (N:P = 29, growth rate of μ = 0.2 d-1) at present-day and high-CO2 concentrations. 14C incubations were performed to determine primary production (PP), comprised of particulate (PO14C) and dissolved organic carbon (DO14C). Concentration and composition of particulate combined carbohydrates (pCCHO) and high-molecular-weight (>1 kDa, HMW) dissolved combined carbohydrates (dCCHO) were determined by ion chromatography. Information on size distribution of ER products was obtained by investigating distinct size classes (10 kDa was significantly different, with a higher mol% of arabinose. The mol% of acidic sugars increased and that of glucose decreased with increasing size of HMW-dCCHO. We conclude that larger polysaccharides follow different production and release pathways than smaller molecules, potentially serving distinct ecological and biogeochemical functions.

  8. Exposure of children to airborne particulate matter of different size fractions during indoor physical education at school

    Energy Technology Data Exchange (ETDEWEB)

    Branis, Martin; Hytychova, Adela [Charles University in Prague, Faculty of Science, Institute for Environmental Studies, Albertov 6, 128 43 Prague 2 (Czech Republic); Safranek, Jiri [Charles University in Prague, Faculty of Physical Education, Department of outdoor sports, Jose Martiho 31, 162 52 Prague 6 (Czech Republic)

    2009-06-15

    Although moderate regular aerobic exercise is recommended for good health, adverse health consequences may be incurred by people who exercise in areas with high ambient pollution, such as in the centres of large cities with dense traffic. The exposure of children during exercise is of special concern because of their higher sensitivity to air pollutants. The size-segregated mass concentration of particulate matter was measured in a naturally ventilated elementary school gym during eight campaigns, seven to ten days long, from November 2005 through August 2006 in a central part of Prague (Czech Republic). The air was sampled using a five-stage cascade impactor. The indoor concentrations of PM{sub 2.5} recorded in the gym exceeded the WHO recommended 24-hour limit of 25 {mu}g m{sup -3} in 50% of the days measured. The average 24-h concentrations of PM{sub 2.5} (24.03 {mu}g m{sup -3}) in the studied school room did not differ much from those obtained from the nearest fixed site monitor (25.47 {mu}g m{sup -3}) and the indoor and ambient concentrations were closely correlated (correlation coefficient 0.91), suggesting a high outdoor-to-indoor penetration rate. The coarse indoor fraction concentration (PM{sub 2.5-10}) was associated with the number of exercising pupils (correlation coefficient 0.77), indicating that human activity is its main source. Considering the high pulmonary ventilation rate of exercising children and high outdoor particulate matter concentrations, the levels of both coarse and fine aerosols may represent a potential health risk for sensitive individuals during their physical education performed in naturally ventilated gyms in urban areas with high traffic intensity. (author)

  9. Effects of Land Use on Concentrations and Chemical Forms of Phosphorus in Different-Size Aggregates

    Science.gov (United States)

    Ahmad, E. H.; Demisie, W.; Zhang, M.

    2017-12-01

    Land use has been recognized as an important driver of environmental change on all spatial and temporal scales. This study was conducted to determine the effects of land uses on phosphorus concentration in bulk soil and in water-stable aggregates in different soils. The study was conducted on three soil types (Ferrosols, Cambosols, and Primosols), which were collected from three different locations from southeast China and under three land uses (Uncultivated, Vegetable and forest land) the region is characterized as a hill and plain area. Accordingly, a total of 24 soil samples were collected. The results showed that average contents of total P were 0.55-1.55 g/kg, 0.28-1.03 g/kg and 0.14-0.8 g/kg for the soils: Cambosols, Ferrosols and Primosols respectively. Vegetable and forest land led to higher total phosphorus contents in these soils than in the uncultivated land. An aggregate fraction of >2 mm under forest land made up the largest percentage (30 up to 70%), whereas the size fraction phosphorus, organic phosphorus and Olsen P and phosphorus forms in the soils. It implies that the conversion of natural ecosystem to vegetable land increased the phosphorus proportion in the soils, which could have negative impact on the environmental quality.

  10. The variability in iron speciation in size fractionated residual oil fly ash particulate matter (ROFA PM).

    Science.gov (United States)

    Pattanaik, Sidhartha; Huggins, Frank E; Huffman, Gerald P

    2016-08-15

    Ambient particulate matter (PM) containing iron can catalyze Fenton reaction leading to the production of reactive oxygen species in cells. It can also catalyze atmospheric redox reaction. These reactions are governed by the physicochemical characteristics of iron in ambient PM. As a surrogate for ambient PM, we prepared residual oil fly ash PM (ROFA PM) in a practical fire tube boiler firing residual oils with varying sulfur and ash contents. The ROFA particles were resolved into fine PM or PM2.5 (aerodynamic diameter (AD)iron speciation in PM2.5+ was ascertained using X-ray absorption spectroscopy and leaching method while that in PM2.5 was reported earlier. The results of both studies are compared to get an insight into the variability in the iron speciation in different size fractions. The results show the predominance of ferric sulfate, with a minor spinal ferrite in both PM (i.e. ZnxNi1-xFe2O4 in PM2.5, ZnFe2O4 in PM2.5+). The iron solubility in ROFA PM depends on its speciation, mode of incorporation of iron into particle's carbonaceous matrix, the grade and composition of oils, and pH of the medium. The soluble fraction of iron in PM is critical in assessing its interaction with the biological systems and its toxic potential. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Acoustic pressure in cavity of variously sized two-dimensional sonic crystals with various filling fractions

    International Nuclear Information System (INIS)

    Wu Liangyu; Chen Lienwen; Liu Chiaming

    2009-01-01

    This study theoretically and experimentally investigates the acoustic pressure in the cavity of a 2D sonic crystal. Such crystals are composed of polymethyl methacrylate cylinders with a square array embedded in air background. The plane wave expansion method and the supercell calculation are employed to calculate the band structure and obtain the defect band. The finite element method is adopted to simulate the pressure field in the sonic crystal and calculate the pressure in the middle of the cavity as a function of frequency. The effects of sizes and filling fractions are investigated, and the quality factor of the cavity is discussed. The measured spectra and pressures in the defect of the sonic crystal demonstrate that the acoustic waves can be localized in the defect at the resonant frequency

  12. Concentration effect on inter-mineral equilibrium isotope fractionation: insights from Mg and Ca isotopic systems

    Science.gov (United States)

    Huang, F.; Wang, W.; Zhou, C.; Kang, J.; Wu, Z.

    2017-12-01

    Many naturally occurring minerals, such as carbonate, garnet, pyroxene, and feldspar, are solid solutions with large variations in chemical compositions. Such variations may affect mineral structures and modify the chemical bonding environment around atoms, which further impacts the equilibrium isotope fractionation factors among minerals. Here we investigated the effects of Mg content on equilibrium Mg and Ca isotope fractionation among carbonates and Ca content on equilibrium Ca isotope fractionation between orthopyroxene (opx) and clinopyroxene (cpx) using first-principles calculations. Our results show that the average Mg-O bond length increases with decreasing Mg/(Mg+Ca) in calcite when it is greater than 1/48[1] and the average Ca-O bond length significantly decreases with decreasing Ca/(Ca+Mg+Fe) in opx when it ranges from 2/16 to 1/48[2]. Equilibrium isotope fractionation is mainly controlled by bond strengths, which could be measured by bond lengths. Thus, 103lnα26Mg/24Mg between dolomite and calcite dramatically increases with decreasing Mg/(Mg+Ca) in calcite [1] and it reaches a constant value when it is lower than 1/48. 103lnα44Ca/40Ca between opx and cpx significantly increases with decreasing Ca content in opx when Ca/(Ca+Mg+Fe) ranges from 2/16 to 1/48 [2]. If Ca/(Ca+Mg+Fe) is below 1/48, 103lnα44Ca/40Ca is not sensitive to Ca content. Based on our results, we conclude that the concentration effect on equilibrium isotope fractionation could be significant within a certain range of chemical composition of minerals, which should be a ubiquitous phenomenon in solid solution systems. [1] Wang, W., Qin, T., Zhou, C., Huang, S., Wu, Z., Huang, F., 2017. GCA 208, 185-197. [2] Feng, C., Qin, T., Huang, S., Wu, Z., Huang, F., 2014. GCA 143, 132-142.

  13. Size fraction assaying of gold bearing rocks (for gold extraction) by instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Ahmed, K.; Dampare, S.B.; Addo, M.A.; Osae, S.; Adotey, D.K.; Adomako, D.

    2005-01-01

    A novel method has been developed for processing and extraction of gold from gold bearing rocks for use by small-scale gold miners in Ghana. The methodology involved crushing of gold bearing hard rocks to fine particles to form a composite sample and screening at a range of sizes. Gold distribution in the composite sample was determined as a function of particle size by using Instrumental Neutron Activation Analysis. The concentrations of gold for the corresponding particle sizes were 16.4 ± 0.17mg/kg for sizes <63μm; 161± 0.75 mg/kg for 63 - 125 μm, 0.53 + 0.03 mg/kg for 125 - 250 μm, 4.66± 0.07 mg/kg for 250 - 355 μm, 1.55 ± 0.06 for 355 - 425 μm, 0.80 ± 0.008 mg/kg for 425 -1000 μm, and 1.27 + 0.05 mg/kg for 1000-2000 μm. The average gold content in a 7.127 kg composite sample based on particle size found to be 3.08 mg/kg. (au)

  14. Chemical profile of size-fractionated soils collected in a semiarid industrial area of Argentina

    Science.gov (United States)

    Morales Del Mastro, Anabella; Pereyra, Marcelo; Londonio, Agustín; Pereyra, Victoria; Rebagliati, Raúl Jiménez; Dawidowski, Laura; Gómez, Darío; Smichowski, Patricia

    2014-12-01

    A study was undertaken to assess the chemical profile of soil collected in Bahía Blanca (Argentina). In this industrial city, semiarid soils are affected by different industrial and agricultural activities, the presence of a saltpeter extraction facility, traffic and increasing urbanization. Sixteen soil samples (superficial and sub-superficial) were collected. Samples were sieved in two fractions (A plasma optical emission spectrometry (ICP OES). Anions (Cl-, F-, SO42-) and cations (K+, Na+ and NH4+) were determined by high performance liquid chromatography (HPLC) after an aqueous extraction. As expected, crustal elements namely, Al, Ca, Fe, Mg and Ti exhibited the highest concentrations. Mean elemental concentration ranged from Na+ ≅ SO42- > K+ > NO3-. Three indicators, namely, (i) coefficient of variation, (ii) coefficient of divergence and (iii) ratio of elemental concentration with respect to Ca were used to assess chemical, spatial and inter-profile variability. Chloride > Ca > Na+ > Mo > SO42-, dominated the variability indicating that these are key chemical markers for future assessment of crustal contribution to airborne particles in the area. The ratios Xi/Ca allowed discriminating the soil of the semi-arid region surrounding Bahía Blanca. The chemical profiles obtained in this study, particularly those of topsoil, will be a key input to characterize soil resuspension and its contribution to airborne particulate matter in a forthcoming receptor model analysis.

  15. Supporting Students to Reason about the Relative Size of Proper and Improper Fractions

    Science.gov (United States)

    Cortina, Jose Luis; Visnovska, Jana

    2015-01-01

    Fractions are a well-researched area; yet, student learning of fractions remains problematic. We outline a novel path to initial fraction learning and document its promise. Building on Freudenthal's analysis of the fraction concept, we regard "comparing," rather than "fracturing," as the primary activity from which students are…

  16. C and N Content in Density Fractions of Whole Soil and Soil Size Fraction Under Cacao Agroforestry Systems and Natural Forest in Bahia, Brazil

    Science.gov (United States)

    Rita, Joice Cleide O.; Gama-Rodrigues, Emanuela Forestieri; Gama-Rodrigues, Antonio Carlos; Polidoro, Jose Carlos; Machado, Regina Cele R.; Baligar, Virupax C.

    2011-07-01

    Agroforestry systems (AFSs) have an important role in capturing above and below ground soil carbon and play a dominant role in mitigation of atmospheric CO2. Attempts has been made here to identify soil organic matter fractions in the cacao-AFSs that have different susceptibility to microbial decomposition and further represent the basis of understanding soil C dynamics. The objective of this study was to characterize the organic matter density fractions and soil size fractions in soils of two types of cacao agroforestry systems and to compare with an adjacent natural forest in Bahia, Brazil. The land-use systems studied were: (1) a 30-year-old stand of natural forest with cacao (cacao cabruca), (2) a 30-year-old stand of cacao with Erythrina glauca as shade trees (cacao + erythrina), and (3) an adjacent natural forest without cacao. Soil samples were collected from 0-10 cm depth layer in reddish-yellow Oxisols. Soil samples was separated by wet sieving into five fraction-size classes (>2000 μm, 1000-2000 μm, 250-1000 μm, 53-250 μm, and cacao AFS soils consisted mainly (65 %) of mega-aggregates (>2000 μm) mixed with macroaggregates (32-34%), and microaggregates (1-1.3%). Soil organic carbon (SOC) and total N content increased with increasing soil size fraction in all land-use systems. Organic C-to-total N ratio was higher in the macroaggregate than in the microaggregate. In general, in natural forest and cacao cabruca the contribution of C and N in the light and heavy fractions was similar. However, in cacao + erythrina the heavy fraction was the most common and contributed 67% of C and 63% of N. Finding of this study shows that the majority of C and N in all three systems studied are found in macroaggregates, particularly in the 250-1000 μm size aggregate class. The heavy fraction was the most common organic matter fraction in these soils. Thus, in mature cacao AFS on highly weathered soils the main mechanisms of C stabilization could be the physical

  17. C and N content in density fractions of whole soil and soil size fraction under cacao agroforestry systems and natural forest in Bahia, Brazil.

    Science.gov (United States)

    Rita, Joice Cleide O; Gama-Rodrigues, Emanuela Forestieri; Gama-Rodrigues, Antonio Carlos; Polidoro, Jose Carlos; Machado, Regina Cele R; Baligar, Virupax C

    2011-07-01

    Agroforestry systems (AFSs) have an important role in capturing above and below ground soil carbon and play a dominant role in mitigation of atmospheric CO(2). Attempts has been made here to identify soil organic matter fractions in the cacao-AFSs that have different susceptibility to microbial decomposition and further represent the basis of understanding soil C dynamics. The objective of this study was to characterize the organic matter density fractions and soil size fractions in soils of two types of cacao agroforestry systems and to compare with an adjacent natural forest in Bahia, Brazil. The land-use systems studied were: (1) a 30-year-old stand of natural forest with cacao (cacao cabruca), (2) a 30-year-old stand of cacao with Erythrina glauca as shade trees (cacao + erythrina), and (3) an adjacent natural forest without cacao. Soil samples were collected from 0-10 cm depth layer in reddish-yellow Oxisols. Soil samples was separated by wet sieving into five fraction-size classes (>2000 μm, 1000-2000 μm, 250-1000 μm, 53-250 μm, and 2000 μm) mixed with macroaggregates (32-34%), and microaggregates (1-1.3%). Soil organic carbon (SOC) and total N content increased with increasing soil size fraction in all land-use systems. Organic C-to-total N ratio was higher in the macroaggregate than in the microaggregate. In general, in natural forest and cacao cabruca the contribution of C and N in the light and heavy fractions was similar. However, in cacao + erythrina the heavy fraction was the most common and contributed 67% of C and 63% of N. Finding of this study shows that the majority of C and N in all three systems studied are found in macroaggregates, particularly in the 250-1000 μm size aggregate class. The heavy fraction was the most common organic matter fraction in these soils. Thus, in mature cacao AFS on highly weathered soils the main mechanisms of C stabilization could be the physical protection within macroaggregate structures thereby

  18. Tidal River Elbe - a sediment budget for the grain size fraction of medium sand

    Science.gov (United States)

    Winterscheid, Axel

    2016-04-01

    Human interventions have a historic and ongoing impact on estuarine sediment budgets across many estuaries worldwide. An early inference was the construction of embankments resulting in a constant loss of intertidal flats. Additionally, settlement activities and large scale land use changes in the upstream catchment areas had also an effect on sediment inflow rates. Today, the navigation channels in estuaries have been deepened for larger and more efficient vessels to reach a well-developed infrastructure of harbors and industrial areas often located far inland. In the past few years and just within the North-East Atlantic, the total annual amount of dredged sediments dumped at sea varied from 80 to 130 million tons (OSPAR Commission). In most estuaries across Europe the resulting human impact on the sediment fluxes and morphodynamics is significant. A good understanding of estuarine processes is essential for determining useful and meaningful measures to mitigate negative effects and to improve the current situation. Maintenance dredging and its environmental effects are therefore in the focus of public attention. Against this background, it is the aim of the presentation to identify and therefore to separate the particular effect that maintenance dredging has on sediment fluxes and budgets in the estuarine environment. Case study is the Tidal River Elbe in Germany, and here we set the focus on the grain size fraction of medium sand. In the past, river engineering measures forced the natural dynamics to form a concentrated stream flow along a fixed channel, except at a number of locations where side channels still exist. In addition to that, the main channel was deepened several times. The last deepening was in 1999/2000. The most significant deepening, however, took place from 1957 to 1962. Until then, an erosion-stable layer of marine clay (in German called "Klei") formed a flat bottom along most sections of the main channel. After removal of this layer of

  19. Transport, retention, and size perturbation of graphene oxide in saturated porous media: Effects of input concentration and grain size

    Science.gov (United States)

    Accurately predicting the fate and transport of graphene oxide (GO) in porous media is critical to assess its environmental impact. In this work, sand column experiments were conducted to determine the effect of input concentration and grain size on transport, retention, and size perturbation of GO ...

  20. The trial of obtaining a high-grade gadolinium concentrate using the fractional precipitation together with the ion exchange

    International Nuclear Information System (INIS)

    Ozga, W.; Soltysiak, I.

    1980-01-01

    The modified fractional precipitation of lanthanon-potassium double chromate was used for preliminary separation of gadolinium concentrate containing 60% Gd 2 O 3 , 33,3% Sm 2 O 3 . The 1-st fraction enriched with samarium (60% Sm 2 O 3 ) and 2-nd fraction enriched with gadolinium (80% Gd 2 O 3 with efficiency of 82% recounting on Gd 2 O 3 ) were obtained. Both fractions were separated by the elution with EDTA solution buffered with ammonium acetate. The good results were obtained by ion exchange separation only of the 1-st fraction. (author)

  1. Fractionation of elements by particle size of ashes ejected from Copahue Volcano, Argentina.

    Science.gov (United States)

    Gómez, Dario; Smichowski, Patricia; Polla, Griselda; Ledesma, Ariel; Resnizky, Sara; Rosa, Susana

    2002-12-01

    The volcano Copahue, Neuquén province, Argentina has shown infrequent explosive eruptions since the 18th century. Recently, eruptive activity and seismicity were registered in the period July-October, 2000. As a consequence, ash clouds were dispersed by winds and affected Caviahue village located at about 9 km east of the volcano. Samples of deposited particles from this area were collected during this episode for their chemical analysis to determine elements of concern with respect to the health of the local population and its environment. Different techniques were used to evaluate the distribution of elements in four particle size ranges from 36 to 300 microm. X-ray powder diffraction (XRD) was selected to detect major components namely, minerals, silicate glass, fragments of rocks and sulfurs. Major and minor elements (Al, Ca, Cl, Fe, K, Mg, Mn, Na, S, Si and Ti), were detected by energy dispersive X ray analysis (EDAX). Trace element (As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, U, V and Zn) content was quantified by inductively coupled plasma-mass spectrometry (ICP-MS). Nuclear activation analysis (NAA) was employed for the determination of Ce, Co, Cs, Eu, Hf, La, Lu, Rb, Sc, Sm, Ta and Yb. An enrichment was observed in the smallest size fraction of volcanic ashes for four elements (As, Cd, Cu and Sb) of particular interest from the environmental and human health point of view.

  2. Association of radionuclides with different molecular size fractions in soil solution: implications for plant uptake

    International Nuclear Information System (INIS)

    Nisbet, A.F.; Shaw, S.; Salbu, B.

    1993-01-01

    The feasibility of using hollow fibre ultrafiltration to determine the molecular size distribution of radionuclides in soil solution was investigated. The physical and chemical composition of soil plays a vital role in determining radionuclide uptake by plant roots. Soil solution samples were extracted from loam, peat and sand soils that had been artificially contaminated with 137 Cs, 90 Sr, 239 Pu and 241 Am six years previously as part of a five-year lysimeter study on radionuclide uptake to crops. Ultrafiltration of soil solution was performed using hollow fibre cartridges with a nominal molecular weight cut off of 3 and 10 kD. The association of 137 Cs, 90 Sr, 239 Pu and 241 Am with different molecular size fractions of the soil solution is discussed in terms of radionuclide bioavailability to cabbage grown in the same three soils. 137 Cs and 90 Sr were present in low molecular weight forms and as such were mobile in soil and potentially available for uptake by the cabbage. In contrast, a large proportion (61-87%) of the 239 Pu and 241 Am were associated with colloidal and high molecular weight material and therefore less available for uptake by plant roots. The contribution from low molecular weight species of 239 Pu and 241 Am to the total activity in soil solution decreased in the order loam ≥ peat ≥ sand. Association of radionuclides with low molecular weight species of less than 3 kD did not, however, automatically imply availability to plants. (author)

  3. Binder fraction reduction in non-ferrous metals concentrates briquetting process

    Directory of Open Access Journals (Sweden)

    M. Jodkowski

    2016-10-01

    Full Text Available The research results on a method of reducing the amount of binder applied during formation of metal concentrates are presented. Research was done on a model copper concentrate, which was mixed in assumed mass fraction with binder, as well as binder with addition of waste polyols. Such mixtures were formed and tested using static compressive strength, both immediately after forming and after the assumed seasoning times: 24, 96, 192 and 336 hours. The results confirm the possibility of binder dose lowering using high-efficiency system of binder dispersing with small addition of waste polyols and by homogeneous mixing of the binder with the material. In all examined cases increase in seasoning time influenced mechanical strength of the formed shapes advantageously.

  4. Separation, fractionation, concentration and drying of food products: Final report, March 4, 1987--March 31, 1988

    Energy Technology Data Exchange (ETDEWEB)

    Merlo, C.A.; Rose, W.W.; Pedersen, L.D.; Brewbaker, P.L.

    1988-03-01

    This project studied energy efficient processes for separation, fractionation, concentration, drying, and recombination of food products, in order to reduce energy requirements for processing, preservation, and transportation. The project had three phases. In the laboratory-scale phase, results of which are summarized in this report, tomato puree was separated by three methods: conventional vacuum filtration, centrifugation, and crossflow microfiltration to produce pulp and serum. Three methods of recombination were examined: homogenizing, stomacher blending, and static (in-line) mixing. Satisfactory recombined purees were obtained. In addition, after centrifugation, the pulp was rinsed producing rinsed-pulp, and the rinse water was added to the serum producing rinse/serum. The rinse/serum was concentrated by evaporation. This was recombined with the rinsed-pulp and water producing satisfactory puree. 11 refs., 18 figs., 18 tabs.

  5. Airstream fractionation of vesicular-arbuscular mycorrhizal fungi: concentration and enumeration of propagules.

    Science.gov (United States)

    Tommerup, I C

    1982-09-01

    Spores and fragments of vesicular-arbuscular mycorrhizal fungi in dry soils were concentrated up to 100-fold when the soils were partitioned by fluidization and elutriation with a series of upward airstreams at progressively increasing velocities. The propagules were transported with the finer soil particles according to their equivalent spherical diameters. The system was used to predict the transport of propagules by wind. Concentrated propagules were rapidly separated from the soil particles in each soil fraction by an aqueous flotation method. The technique is proposed as a quantitative method for estimating the numbers of spores and fragments of mycorrhizae. The scheme includes a viability test that was used to differentiate between potentially infective propagules and those that were either dormant or incapable of regrowth.

  6. Trace elements in particulate matter from metropolitan regions of Northern China: Sources, concentrations and size distributions.

    Science.gov (United States)

    Pan, Yuepeng; Tian, Shili; Li, Xingru; Sun, Ying; Li, Yi; Wentworth, Gregory R; Wang, Yuesi

    2015-12-15

    Public concerns over airborne trace elements (TEs) in metropolitan areas are increasing, but long-term and multi-site observations of size-resolved aerosol TEs in China are still lacking. Here, we identify highly elevated levels of atmospheric TEs in megacities and industrial sites in a Beijing-Tianjin-Hebei urban agglomeration relative to background areas, with the annual mean values of As, Pb, Ni, Cd and Mn exceeding the acceptable limits of the World Health Organization. Despite the spatial variability in concentrations, the size distribution pattern of each trace element was quite similar across the region. Crustal elements of Al and Fe were mainly found in coarse particles (2.1-9 μm), whereas the main fraction of toxic metals, such as Cu, Zn, As, Se, Cd and Pb, was found in submicron particles (metals were enriched by over 100-fold relative to the Earth's crust. The size distributions of Na, Mg, K, Ca, V, Cr, Mn, Ni, Mo and Ba were bimodal, with two peaks at 0.43-0.65 μm and 4.7-5.8 μm. The combination of the size distribution information, principal component analysis and air mass back trajectory model offered a robust technique for distinguishing the main sources for airborne TEs, e.g., soil dust, fossil fuel combustion and industrial emissions, at different sites. In addition, higher elemental concentrations coincided with westerly flow, indicating that polluted soil and fugitive dust were major sources of TEs on the regional scale. However, the contribution of coal burning, iron industry/oil combustion and non-ferrous smelters to atmospheric metal pollution in Northern China should be given more attention. Considering that the concentrations of heavy metals associated with fine particles in the target region were significantly higher than those in other Asian sites, the implementations of strict environmental standards in China are required to reduce the amounts of these hazardous pollutants released into the atmosphere. Copyright © 2015 Elsevier B

  7. Radiocesium distribution in aggregate-size fractions of cropland and forest soils affected by the Fukushima nuclear accident.

    Science.gov (United States)

    Koarashi, Jun; Nishimura, Syusaku; Atarashi-Andoh, Mariko; Matsunaga, Takeshi; Sato, Tsutomu; Nagao, Seiya

    2018-08-01

    The Fukushima Daiichi nuclear power plant accident caused serious radiocesium ( 137 Cs) contamination in soils in a range of terrestrial ecosystems. It is well documented that the interaction of 137 Cs with soil constituents, particularly clay minerals, in surface soil layers exerts strong control on the behavior of this radionuclide in the environment; however, there is little understanding of how soil aggregation-the binding of soil particles together into aggregates-can affect the mobility and bioavailability of 137 Cs in soils. To explore this, soil samples were collected at seven sites under different land-use conditions in Fukushima and were separated into four aggregate-size fractions: clay-sized (fractions were then analyzed for 137 Cs content and extractability and mineral composition. In forest soils, aggregate formation was significant, and 69%-83% of 137 Cs was associated with macroaggregates and sand-sized aggregates. In contrast, there was less aggregation in agricultural field soils, and approximately 80% of 137 Cs was in the clay- and silt-sized fractions. Across all sites, the 137 Cs extractability was higher in the sand-sized aggregate fractions than in the clay-sized fractions. Mineralogical analysis showed that, in most soils, clay minerals (vermiculite and kaolinite) were present even in the larger-sized aggregate fractions. These results demonstrate that larger-sized aggregates are a significant reservoir of potentially mobile and bioavailable 137 Cs in organic-rich (forest and orchard) soils. Our study suggests that soil aggregation reduces the mobility of particle-associated 137 Cs through erosion and resuspension and also enhances the bioavailability of 137 Cs in soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Short-term bioavailability of carbon in soil organic matter fractions of different particle sizes and densities in grassland ecosystems.

    Science.gov (United States)

    Breulmann, Marc; Masyutenko, Nina Petrovna; Kogut, Boris Maratovich; Schroll, Reiner; Dörfler, Ulrike; Buscot, François; Schulz, Elke

    2014-11-01

    The quality, stability and availability of organic carbon (OC) in soil organic matter (SOM) can vary widely between differently managed ecosystems. Several approaches have been developed for isolating SOM fractions to examine their ecological roles, but links between the bioavailability of the OC of size-density fractions and soil microbial communities have not been previously explored. Thus, in the presented laboratory study we investigated the potential bioavailability of OC and the structure of associated microbial communities in different particle-size and density fractions of SOM. For this we used samples from four grassland ecosystems with contrasting management intensity regimes and two soil types: a Haplic Cambisol and a typical Chernozem. A combined size-density fractionation protocol was applied to separate clay-associated SOM fractions (CF1, <1 μm; CF2, 1-2 μm) from light SOM fractions (LF1, <1.8 g cm(-3); LF2, 1.8-2.0 g cm(-3)). These fractions were used as carbon sources in a respiration experiment to determine their potential bioavailability. Measured CO2-release was used as an index of substrate accessibility and linked to the soil microbial community structure, as determined by phospholipid fatty acids (PLFA) analysis. Several key factors controlling decomposition processes, and thus the potential bioavailability of OC, were identified: management intensity and the plant community composition of the grasslands (both of which affect the chemical composition and turnover of OC) and specific properties of individual SOM fractions. The PLFA patterns highlighted differences in the composition of microbial communities associated with the examined grasslands, and SOM fractions, providing the first broad insights into their active microbial communities. From observed interactions between abiotic and biotic factors affecting the decomposition of SOM fractions we demonstrate that increasing management intensity could enhance the potential bioavailability of

  9. Speciation of copper and zinc in size-fractionated atmospheric particulate matter using total reflection mode X-ray absorption near-edge structure spectrometry

    International Nuclear Information System (INIS)

    Osan, Janos; Meirer, Florian; Groma, Veronika; Toeroek, Szabina; Ingerle, Dieter; Streli, Christina; Pepponi, Giancarlo

    2010-01-01

    The health effects of aerosol depend on the size distribution and the chemical composition of the particles. Heavy metals of anthropogenic origin are bound to the fine aerosol fraction (PM 2.5 ). The composition and speciation of aerosol particles can be variable in time, due to the time-dependence of anthropogenic sources as well as meteorological conditions. Synchrotron-radiation total reflection X-ray fluorescence (SR-TXRF) provides very high sensitivity for characterization of atmospheric particulate matter. X-ray absorption near-edge structure (XANES) spectrometry in conjunction with TXRF detection can deliver speciation information on heavy metals in aerosol particles collected directly on the reflector surface. The suitability of TXRF-XANES for copper and zinc speciation in size-fractionated atmospheric particulate matter from a short sampling period is presented. For high size resolution analysis, atmospheric aerosol particles were collected at different urban and rural locations using a 7-stage May cascade impactor having adapted for sampling on Si wafers. The thin stripe geometry formed by the particulate matter deposited on the May-impactor plates is ideally suited to SR-TXRF. Capabilities of the combination of the May-impactor sampling and TXRF-XANES measurements at HASYLAB Beamline L to Cu and Zn speciation in size-fractionated atmospheric particulate matter are demonstrated. Information on Cu and Zn speciation could be performed for elemental concentrations as low as 140 pg/m 3 . The Cu and Zn speciation in the different size fraction was found to be very distinctive for samples of different origin. Zn and Cu chemical state typical for soils was detected only in the largest particles studied (2-4 μm fraction). The fine particles, however, contained the metals of interest in the sulfate and nitrate forms.

  10. Characterization of Time-Dependent Contact Angles for Oleic Acid Mixed Sands with Different Particle Size Fractions

    DEFF Research Database (Denmark)

    Wijewardana, Y. N. S.; Kawamoto, Ken; Komatsu, Toshiko

    2014-01-01

    ) mixed sands representing four different particle size fractions ranging from 0.105 to 0.84 mm. Initial soil-water contact angle (αi), and the time dependence of contact angle were measured by the sessile drop method. Results showed that the αi value for fine and middle sand fractions increased rapidly...... in contact angle (α), well captured the time dependence of α....

  11. Particle-size fractionation and stable carbon isotope distribution applied to the study of soil organic matter dynamics

    International Nuclear Information System (INIS)

    Cerri, C.; Feller, C.; Balesdent, J.; Victoria, R.; Plenecassagne, A.

    1985-01-01

    The present Note concerns the dynamics of organic matter in soils under forest (C 3 -type vegetation) and 12 and 50 years old sugar-cane (C 4 -type vegetation) cultivation. The decomposition rate of ‘forest organic matter” and the accumulation rate of “sugar-cane organic matter” are estimated through 13 C measurements of total soil and different organic fractions (particle-size, fractionation) [fr

  12. Diurnal and seasonal variations of concentration and size distribution of nano aerosols (10-1100 nm) enclosing radon decay products in the Postojna Cave, Slovenia.

    Science.gov (United States)

    Bezek, M; Gregoric, A; Kávási, N; Vaupotic, J

    2012-11-01

    At the lowest point along the tourist route in the Postojna Cave, the activity concentration of radon ((222)Rn) short-lived decay products and number concentration and size distribution of background aerosol particles in the size range of 10-1100 nm were measured. In the warm yearly season, aerosol concentration was low (52 cm(-3)) with 21 % particles smaller than 50 nm, while in the cold season, it was higher (1238 cm(-3)) with 8 % of <50 nm particles. Radon activity concentrations were 4489 and 1108 Bq m(-3), and fractions of unattached radon decay products were 0.62 and 0.13, respectively.

  13. Tunable solvation effects on the size-selective fractionation of metal nanoparticles in CO2 gas-expanded solvents.

    Science.gov (United States)

    Anand, Madhu; McLeod, M Chandler; Bell, Philip W; Roberts, Christopher B

    2005-12-08

    This paper presents an environmentally friendly, inexpensive, rapid, and efficient process for size-selective fractionation of polydisperse metal nanoparticle dispersions into multiple narrow size populations. The dispersibility of ligand-stabilized silver and gold nanoparticles is controlled by altering the ligand tails-solvent interaction (solvation) by the addition of carbon dioxide (CO2) gas as an antisolvent, thereby tailoring the bulk solvent strength. This is accomplished by adjusting the CO2 pressure over the liquid, resulting in a simple means to tune the nanoparticle precipitation by size. This study also details the influence of various factors on the size-separation process, such as the types of metal, ligand, and solvent, as well as the use of recursive fractionation and the time allowed for settling during each fractionation step. The pressure range required for the precipitation process is the same for both the silver and gold particles capped with dodecanethiol ligands. A change in ligand or solvent length has an effect on the interaction between the solvent and the ligand tails and therefore the pressure range required for precipitation. Stronger interactions between solvent and ligand tails require greater CO2 pressure to precipitate the particles. Temperature is another variable that impacts the dispersibility of the nanoparticles through changes in the density and the mole fraction of CO2 in the gas-expanded liquids. Recursive fractionation for a given system within a particular pressure range (solvent strength) further reduces the polydispersity of the fraction obtained within that pressure range. Specifically, this work utilizes the highly tunable solvent properties of organic/CO2 solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (2 to 12 nm) into more monodisperse fractions (+/-2 nm). In addition to providing efficient separation of the particles, this process also allows all of the solvent and

  14. Extraction Kinetics and Molecular Size Fractionation of Humic Substances From Two Brazilian Soils

    Directory of Open Access Journals (Sweden)

    Dick Deborah Pinheiro

    1999-01-01

    Full Text Available In the present study, the extraction behaviour of humic substances (HS from an Oxisol and a Mollisol from South Brazil, by using 0.1 and 0.5 mol L-1 NaOH and 0.15 mol L-1 neutral pyrophosphate solutions, respectively, was systematically studied. The kinetics and efficiency of HS extraction were evaluated by means of UV/Vis spectroscopy. The isolated humic acids (HA and fulvic acids (FA were size-classified by multistage ultrafiltration (six fractions in the molecular weight range of 1 to 100 kDa. The obtained data show that the HS extraction yield depended not only on the extractant, but also on the soil type. Within 3 h approximately 90% of the soluble HS could be extracted following complex extraction kinetics by both methods and none or little structural modification was verified as observed from their stable extinction ratio E350/E550. In the Mollisol the pyrophosphate extraction was more effective, suggesting that a great part of HS occurred as macromolecules bonded to clay minerals and aggregated between themselves through cationic bridges. In the Oxisol a higher HS yield was verified with the alkaline method, presumably due to HS fixation onto the oxide surface by H-bonds and/or surface complexation reactions. In general, HS extracted by the pyrophosphate procedure showed higher molecular weights than those extracted by NaOH.

  15. Iron Mineralogy and Speciation in Clay-Sized Fractions of Chinese Desert Sediments

    Science.gov (United States)

    Lu, Wanyi; Zhao, Wancang; Balsam, William; Lu, Huayu; Liu, Pan; Lu, Zunli; Ji, Junfeng

    2017-12-01

    Iron released from Asian desert dust may be an important source of bioavailable iron for the North Pacific Ocean and thereby may stimulate primary productivity. However, the Fe species of the fine dusts from this source region are poorly characterized. Here we investigate iron species and mineralogy in the clay-sized fractions (iron phases (ferrihydrite and lepidocrocite) and reducible iron oxides (dominated by goethite) are 0.81 wt % and 2.39 wt %, respectively, and Fe dissolved from phyllosilicates extracted by boiling HCl (dominated by chlorite) is 3.15 wt %. Dusts originating from deserts in northwestern China, particularly the Taklimakan desert, are relatively enriched in easily reducible Fe phases, probably due to abundant Fe contained in fresh weathering products resulting from the rapid erosion associated with active uplift of mountains to the west. Data about Fe speciation and mineralogy in Asian dust sources will be useful for improving the quantification of soluble Fe supplied to the oceans, especially in dust models.

  16. Eutrophication effects on phytoplankton size-fractioned biomass and production at a tropical estuary.

    Science.gov (United States)

    Guenther, Mariana; Araújo, Moacyr; Flores-Montes, Manuel; Gonzalez-Rodriguez, Eliane; Neumann-Leitão, Sigrid

    2015-02-28

    Size-fractioned phytoplankton (pico, nano and microplankton) biomass and production were estimated throughout a year at Recife harbor (NE Brazil), a shallow well mixed tropical hypereutrophic estuary with short residence times but restricted water renewal. Intense loads of P-PO4 (maximum 14 μM) resulted in low N:P ratios (around 2:1), high phytoplankton biomass (B=7.1-72 μg chl-a L(-1)), production (PP=10-2657 μg C L(-1) h(-1)) and photosynthetic efficiency (P(B)=0.5-45 μg C μg chl-a(-1)), but no oxygen depletion (average O2 saturation: 109.6%). Nanoplankton dominated phytoplankton biomass (66%) but micro- and nanoplankton performed equivalent primary production rates (47% each). Production-biomass models indicate an export of the exceeding microplankton biomass during most of the year, possibly through grazing. The intense and constant nutrient and organic matter loading at Recife harbor is thus supporting the high microplankton productivity that is not accumulating on the system nor contributing to oxygen depletion, but supporting the whole system's trophic web. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Inverse size scaling of the nucleolus by a concentration-dependent phase transition.

    Science.gov (United States)

    Weber, Stephanie C; Brangwynne, Clifford P

    2015-03-02

    Just as organ size typically increases with body size, the size of intracellular structures changes as cells grow and divide. Indeed, many organelles, such as the nucleus [1, 2], mitochondria [3], mitotic spindle [4, 5], and centrosome [6], exhibit size scaling, a phenomenon in which organelle size depends linearly on cell size. However, the mechanisms of organelle size scaling remain unclear. Here, we show that the size of the nucleolus, a membraneless organelle important for cell-size homeostasis [7], is coupled to cell size by an intracellular phase transition. We find that nucleolar size directly scales with cell size in early C. elegans embryos. Surprisingly, however, when embryo size is altered, we observe inverse scaling: nucleolar size increases in small cells and decreases in large cells. We demonstrate that this seemingly contradictory result arises from maternal loading of a fixed number rather than a fixed concentration of nucleolar components, which condense into nucleoli only above a threshold concentration. Our results suggest that the physics of phase transitions can dictate whether an organelle assembles, and, if so, its size, providing a mechanistic link between organelle assembly and cell size. Since the nucleolus is known to play a key role in cell growth, this biophysical readout of cell size could provide a novel feedback mechanism for growth control. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Heavy metal pollution decreases microbial abundance, diversity and activity within particle-size fractions of a paddy soil.

    Science.gov (United States)

    Chen, Junhui; He, Feng; Zhang, Xuhui; Sun, Xuan; Zheng, Jufeng; Zheng, Jinwei

    2014-01-01

    Chemical and microbial characterisations of particle-size fractions (PSFs) from a rice paddy soil subjected to long-term heavy metal pollution (P) and nonpolluted (NP) soil were performed to investigate whether the distribution of heavy metals (Cd, Cu, Pb and Zn) regulates microbial community activity, abundance and diversity at the microenvironment scale. The soils were physically fractionated into coarse sand, fine sand, silt and clay fractions. Long-term heavy metal pollution notably decreased soil basal respiration (a measurement of the total activity of the soil microbial community) and microbial biomass carbon (MBC) across the fractions by 3-45% and 21-53%, respectively. The coarse sand fraction was more affected by pollution than the clay fraction and displayed a significantly lower MBC content and respiration and dehydrogenase activity compared with the nonpolluted soils. The abundances and diversities of bacteria were less affected within the PSFs under pollution. However, significant decreases in the abundances and diversities of fungi were noted, which may have strongly contributed to the decrease in MBC. Sequencing of denaturing gradient gel electrophoresis bands revealed that the groups Acidobacteria, Ascomycota and Chytridiomycota were clearly inhibited under pollution. Our findings suggest that long-term heavy metal pollution decreased the microbial biomass, activity and diversity in PSFs, particularly in the large-size fractions. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  19. Selective Dissolution Techniques, X-Ray Diffraction and Moessbauer Spectroscopy Studies of Forms of Fe in Particle-Size Fractions of an Entic Haplustoll

    International Nuclear Information System (INIS)

    Acebal, S. G.; Aguirre, M. E.; Santamaria, R. M.; Mijovilovich, A.; Petrick, S.; Saragovi, C.

    2003-01-01

    Particle-size fractions (o = mean diameter, 5-2 μm, 2-1 μm, and 57 Fe Moessbauer spectroscopy (MS). Quartz, feldspar, smectite, illite and interstratified illite-smectite are the dominant minerals whereas Fe oxides and oxy-hydroxides are present in low concentration but increase as particle size decreases. Poorly crystallized oxides (highly Al-substituted hematite and goethite) amounts are lower, comparable to or slightly higher than the hematite amounts in the o 5-2 μm, 2-1 μm and 3+ and Fe 2+ are associated to the clay minerals and/or hydroxyl-interlayered 2:1 type material present; part of this Fe 3+ is located in the hydroxy-interlayers its amount being higher in the smallest fraction. Any possible changes after the PY and NaOH treatments were not detected by MS.

  20. Results of observations of the tritium concentration in water fractions in the disposition regions of tritium laboratories

    International Nuclear Information System (INIS)

    Koval, G.N.; Kuzmina, A.I.; Kolomiets, N.F.; Svarichevskaya, E.V.; Rogosin, V.N.; Svyatun, O.V.

    1995-01-01

    In this paper results of the long term of control of tritium concentration in the water fractions in the region close to the tritium laboratories of INR NAS of Ukraine are presented. The regular observations for the tritium concentration in the water fractions (thawed water of the snow cover, birch juice and sewer water) in the influence region of tritium laboratories shows small amount of tritium concentration in all kinds of investigated water fractions in comparison with the tritium concentration in the reper points. The proper connection of the levels of tritium concentration of the water samples with the quantity of the technology production is observed. In common, the tritium pollution on the territory of INR shows the tendency for a considerable decrease of the environmental pollution levels from year to year. It can be explained by the perfection of the production technology of tritium structures and targets as well as the rising of the qualification of the personnel. 3 refs., 4 figs

  1. Mapping soil particle-size fractions: A comparison of compositional kriging and log-ratio kriging

    Science.gov (United States)

    Wang, Zong; Shi, Wenjiao

    2017-03-01

    Soil particle-size fractions (psf) as basic physical variables need to be accurately predicted for regional hydrological, ecological, geological, agricultural and environmental studies frequently. Some methods had been proposed to interpolate the spatial distributions of soil psf, but the performance of compositional kriging and different log-ratio kriging methods is still unclear. Four log-ratio transformations, including additive log-ratio (alr), centered log-ratio (clr), isometric log-ratio (ilr), and symmetry log-ratio (slr), combined with ordinary kriging (log-ratio kriging: alr_OK, clr_OK, ilr_OK and slr_OK) were selected to be compared with compositional kriging (CK) for the spatial prediction of soil psf in Tianlaochi of Heihe River Basin, China. Root mean squared error (RMSE), Aitchison's distance (AD), standardized residual sum of squares (STRESS) and right ratio of the predicted soil texture types (RR) were chosen to evaluate the accuracy for different interpolators. The results showed that CK had a better accuracy than the four log-ratio kriging methods. The RMSE (sand, 9.27%; silt, 7.67%; clay, 4.17%), AD (0.45), STRESS (0.60) of CK were the lowest and the RR (58.65%) was the highest in the five interpolators. The clr_OK achieved relatively better performance than the other log-ratio kriging methods. In addition, CK presented reasonable and smooth transition on mapping soil psf according to the environmental factors. The study gives insights for mapping soil psf accurately by comparing different methods for compositional data interpolation. Further researches of methods combined with ancillary variables are needed to be implemented to improve the interpolation performance.

  2. In situ acidity and pH of size-fractionated aerosols during a recent smoke-haze episode in Southeast Asia.

    Science.gov (United States)

    Behera, Sailesh N; Cheng, Jinping; Balasubramanian, Rajasekhar

    2015-10-01

    The characterization of aerosol acidity has received increased attention in recent years due to its influence on atmospheric visibility, climate change and human health. Distribution of water soluble inorganic (WSI) ions in 12 different size fractions of aerosols was investigated under two different atmospheric conditions (smoke-haze and non-haze periods) in 2012 using the Micro-Orifice Uniform Deposit Impactor (MOUDI) and nano-MOUDI for the first time in Singapore. To estimate the in situ acidity ([H(+)]Ins) and in situ aerosol pH (pHIS), the Aerosol Inorganic Model version-IV under deliquescent mode of airborne particles was used at prevailing ambient temperature and relative humidity. The study revealed an increase in the levels of airborne particulate matter (PM) mass and concentrations of WSI ions for all size fractions during the smoke-haze period, which was caused by the trans-boundary transport of biomass burning-impacted air masses from Indonesia. A bimodal distribution was observed for concentrations of SO4(2-), NO3(-), Cl(-), K(+) and Na(+), whereas concentrations of NH4(+), Ca(2+) and Mg(2+) showed a single mode distribution. The concentration of WSI ions in PM1.8 during the smoke-haze period increased by 3.8 (for SO4(2-)) to 10.5 (for K(+)) times more than those observed during the non-haze period. The pHIS were observed to be lower during the smoke-haze period than that during the non-haze period for all size fractions of PM, indicating that atmospheric aerosols were more acidic due to the influence of biomass burning emissions. The particles in the accumulation mode were more acidic than those in the coarse mode.

  3. Concentration of carbonate admixture from opalized tuff into one separate fraction

    International Nuclear Information System (INIS)

    Bogoevski, Slobodan; Boshkovski, Boshko

    2016-01-01

    White opalized tuff (from the Strmosh locality, Probishtip), as a raw silicate amorphous material, contains some quantity of admixtures. The total quantity of admixtures amounts is about 8% mass. Mine powdery ingredients are homogeneously distributed into the basic silicate mass.Carbonate material is a significant part of present admixtures, and it is possible to be separated with controlled milling. Milling parameters (type and time of milling) enables to concentrate the present CaCO 3 in granulometric fraction<0.032 μm, after 30 min. milling. Reliable evidence about afore mentioned separation is shown with simultaneous view of the results of silicate chemical analysis, DT/TG analysis (750 - 850 °C), and sieve-analysis.From the X-ray analysis it is evident that the present carbonate material exists in crypto crystal to amorphous state. The space where CaCO 3 is hidden, presents the place between basic silicate particles inside the groups, generally with dimensions about 40 to 60 μm. The concentration of CaCO 3 appears when this particle group goes to the process of disintegration. (author)

  4. Measurements of the size dependence of the concentration of nonvolatile material in fog droplets

    Science.gov (United States)

    Ogren, J. A.; Noone, K. J.; Hallberg, A.; Heintzenberg, J.; Schell, D.; Berner, A.; Solly, I.; Kruisz, C.; Reischl, G.; Arends, B. G.; Wobrock, W.

    1992-11-01

    Measurements of the size dependence of the mass concentration of nonvolatile material dissolved and suspended in fog droplets were obtained with three complementary approaches, covering a size range from c. 1 50µm diameter: a counterflow virtual impactor, an eight-stage aerosol impactor, and a two-stage fogwater impactor. Concentrations were observed to decrease with size over the entire range, contrary to expectations of increasing concentrations at larger sizes. It is possible that the larger droplets had solute concentrations that increased with increasing size, but that the increase was too weak for the measurements to resolve. Future studies should consider the hypothesis that the droplets were coated with a surface-active substance that hindered their uptake of water.

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

    Science.gov (United States)

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

    2012-01-01

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

  6. Inert gases in a terra sample - Measurements in six grain-size fractions and two single particles from Lunar 20.

    Science.gov (United States)

    Heymann, D.; Lakatos, S.; Walton, J. R.

    1973-01-01

    Review of the results of inert gas measurements performed on six grain-size fractions and two single particles from four samples of Luna 20 material. Presented and discussed data include the inert gas contents, element and isotope systematics, radiation ages, and Ar-36/Ar-40 systematics.

  7. Diurnal and seasonal variations of concentration and size distribution of nano aerosols (10-1100 nm) enclosing radon decay products in the Postojna Cave, Slovenia

    International Nuclear Information System (INIS)

    Bezek, M.; Gregoric, A.; Kavasi, N.; Vaupotic, J.

    2012-01-01

    At the lowest point along the tourist route in the Postojna Cave, the activity concentration of radon ( 222 Rn) short-lived decay products and number concentration and size distribution of background aerosol particles in the size range of 10-1100 nm were measured. In the warm yearly season, aerosol concentration was low (52 cm -3 ) with 21 % particles smaller than 50 nm, while in the cold season, it was higher (1238 cm -3 ) with 8 % of -3 , and fractions of unattached radon decay products were 0.62 and 0.13, respectively. (authors)

  8. A Nanometer Aerosol Size Analyzer (nASA) for Rapid Measurement of High-concentration Size Distributions

    International Nuclear Information System (INIS)

    Han, H.-S.; Chen, D.-R.; Pui, David Y.H.; Anderson, Bruce E.

    2000-01-01

    We have developed a fast-response nanometer aerosol size analyzer (nASA) that is capable of scanning 30 size channels between 3 and 100 nm in a total time of 3 s. The analyzer includes a bipolar charger (Po 210 ), an extended-length nanometer differential mobility analyzer (Nano-DMA), and an electrometer (TSI 3068). This combination of components provides particle size spectra at a scan rate of 0.1 s per channel free of uncertainties caused by response-time-induced smearing. The nASA thus offers a fast response for aerosol size distribution measurements in high-concentration conditions and also eliminates the need for applying a de-smearing algorithm to resulting data. In addition, because of its thermodynamically stable means of particle detection, the nASA is useful for applications requiring measurements over a broad range of sample pressures and temperatures. Indeed, experimental transfer functions determined for the extended-length Nano-DMA using the tandem differential mobility analyzer (TDMA) technique indicate the nASA provides good size resolution at pressures as low as 200 Torr. Also, as was demonstrated in tests to characterize the soot emissions from the J85-GE engine of a T-38 aircraft, the broad dynamic concentration range of the nASA makes it particularly suitable for studies of combustion or particle formation processes. Further details of the nASA performance as well as results from calibrations, laboratory tests and field applications are presented below

  9. The optimal fraction size in high-dose-rate brachytherapy: dependency on tissue repair kinetics and low-dose rate

    International Nuclear Information System (INIS)

    Sminia, Peter; Schneider, Christoph J.; Fowler, Jack F.

    2002-01-01

    Background and Purpose: Indications of the existence of long repair half-times on the order of 2-4 h for late-responding human normal tissues have been obtained from continuous hyperfractionated accelerated radiotherapy (CHART). Recently, these data were used to explain, on the basis of the biologically effective dose (BED), the potential superiority of fractionated high-dose rate (HDR) with large fraction sizes of 5-7 Gy over continuous low-dose rate (LDR) irradiation at 0.5 Gy/h in cervical carcinoma. We investigated the optimal fraction size in HDR brachytherapy and its dependency on treatment choices (overall treatment time, number of HDR fractions, and time interval between fractions) and treatment conditions (reference low-dose rate, tissue repair characteristics). Methods and Materials: Radiobiologic model calculations were performed using the linear-quadratic model for incomplete mono-exponential repair. An irradiation dose of 20 Gy was assumed to be applied either with HDR in 2-12 fractions or continuously with LDR for a range of dose rates. HDR and LDR treatment regimens were compared on the basis of the BED and BED ratio of normal tissue and tumor, assuming repair half-times between 1 h and 4 h. Results: With the assumption that the repair half-time of normal tissue was three times longer than that of the tumor, hypofractionation in HDR relative to LDR could result in relative normal tissue sparing if the optimum fraction size is selected. By dose reduction while keeping the tumor BED constant, absolute normal tissue sparing might therefore be achieved. This optimum HDR fraction size was found to be largely dependent on the LDR dose rate. On the basis of the BED NT/TUM ratio of HDR over LDR, 3 x 6.7 Gy would be the optimal HDR fractionation scheme for replacement of an LDR scheme of 20 Gy in 10-30 h (dose rate 2-0.67 Gy/h), while at a lower dose rate of 0.5 Gy/h, four fractions of 5 Gy would be preferential, still assuming large differences between tumor

  10. Treatment of acne scarring using a dual-spot-size ablative fractionated carbon dioxide laser: review of the literature.

    Science.gov (United States)

    Tierney, Emily P

    2011-07-01

    Fractional photothermolysis has been reported in the literature to improve pigmentary and textural changes associated with acne scarring. To review the literature for the treatment of acne scarring using nonablative fractional laser (NAFL) and ablative fractional laser (AFL) resurfacing. Review of the Medline literature evaluating NAFL and AFL for acne scarring. NAFL and AFL are safe and effective treatments for acne scarring. It is likely that the controlled, limited dermal heating of fractional resurfacing initiates a cascade of events in which normalization of the collagenesis-collagenolysis cycle occurs. We present the results of a patient treated using a novel dual-spot-size AFL device. Three months after the final treatment, the patient reported 75% improvement in acne scarring and 63% overall improvement in photoaging. Fractionated resurfacing for the treatment of acne scarring is associated with lesser risks of side effects of prolonged erythema and risks of delayed-onset dyspigmentation and scarring which complicate traditional ablative laser resurfacing approaches. We present herein preliminary data suggesting that a dual-spot-size AFL device presents novel advantages of improving texture and pigmentation in acne scarring and photoaging. © 2011 by the American Society for Dermatologic Surgery, Inc.

  11. Efficacy of soluble glycoprotein fraction from Allium sativum purified by size exclusion chromatography on murine Schistosomiasis mansoni.

    Science.gov (United States)

    Aly, Ibrahim; Taher, Eman E; El-Sayed, Hoda; Mohammed, Faten A; ELnain, Gehan; Hamad, Rabab S; Bayoumy, Elsayed M

    2017-06-01

    In this work, the efficiency of crude MeOH extracts and soluble glycoprotein fraction of Allium sativum purified by size-exclusion chromatography (SEC) on parasitological, histopathological and some biochemical parameters in Schistosoma mansoni infected mice were investigated. Animals were infected by tail immersion with 100 cercariae/each mouse and divided into five groups in addition to the normal control. The results revealed a significant decrease in mean worm burden in all treated mice especially in the group treated with soluble glycoprotein fraction of A. sativum as compared to infected non-treated control with the disappearance of female worms. Administration of the studied extracts revealed remarkable amelioration in the levels of all the measured parameters in S. mansoni infected mice. In addition, treatment of mice with crude A. sativum MeOH extract and soluble glycoprotein fraction of A. sativum decreased significantly the activities of studied enzymes as compared to the infected untreated group. The highest degrees of enhancement in pathological changes was observed in the treated one with soluble glycoprotein fraction of A. sativum compared to the infected group represented by small sized, late fibro-cellular granuloma, the decrease in cellular constituents and degenerative changes in eggs. In conclusion, A. sativum treatment had effective schistosomicidal activities, through reduction of worm burden and tissue eggs, especially when it was given in purified glycoprotein fraction. Moreover, the soluble glycoprotein fraction of A. sativum largely modulates both the size and the number of granulomas. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Aircraft observations and model simulations of concentration and particle size distribution in the Eyjafjallajökull volcanic ash cloud

    Directory of Open Access Journals (Sweden)

    H. F. Dacre

    2013-02-01

    Full Text Available The Eyjafjallajökull volcano in Iceland emitted a cloud of ash into the atmosphere during April and May 2010. Over the UK the ash cloud was observed by the FAAM BAe-146 Atmospheric Research Aircraft which was equipped with in-situ probes measuring the concentration of volcanic ash carried by particles of varying sizes. The UK Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME has been used to simulate the evolution of the ash cloud emitted by the Eyjafjallajökull volcano during the period 4–18 May 2010. In the NAME simulations the processes controlling the evolution of the concentration and particle size distribution include sedimentation and deposition of particles, horizontal dispersion and vertical wind shear. For travel times between 24 and 72 h, a 1/t relationship describes the evolution of the concentration at the centre of the ash cloud and the particle size distribution remains fairly constant. Although NAME does not represent the effects of microphysical processes, it can capture the observed decrease in concentration with travel time in this period. This suggests that, for this eruption, microphysical processes play a small role in determining the evolution of the distal ash cloud. Quantitative comparison with observations shows that NAME can simulate the observed column-integrated mass if around 4% of the total emitted mass is assumed to be transported as far as the UK by small particles (< 30 μm diameter. NAME can also simulate the observed particle size distribution if a distal particle size distribution that contains a large fraction of < 10 μm diameter particles is used, consistent with the idea that phraetomagmatic volcanoes, such as Eyjafjallajökull, emit very fine particles.

  13. The effect of particle size and concentration on the flow properties of a homogeneous slurry

    International Nuclear Information System (INIS)

    Abbas, M.A.; Crowe, C.T.

    1986-01-01

    This paper presents the results of the effects of particle size and concentration on the velocity distribution in the fully developed flow of a homogeneous slurry. The slurry consisted of chloroform and silica gel with matched index of refraction to enable Laser-Doppler anemometry (LDA) measurements through the mixture. Slurries with two particle sizes and solids concentration up to 30% by volume were studied. Measurements were made over a Reynolds number range of 1,200 to 30,000

  14. Measurement of the tritium concentration in the fractionated distillate from environmental water samples.

    Science.gov (United States)

    Atkinson, Robert; Eddy, Teresa; Kuhne, Wendy; Jannik, Tim; Brandl, Alexander

    2014-09-01

    Standard procedures for the measurement of tritium in water samples often require distillation of an appropriate sample aliquot. This distillation process may result in a fractionation of tritiated water and regular light water due to the vapor pressure isotope effect, introducing either a bias or an additional contribution to the total tritium measurement uncertainty. The current study investigates the relative change in vapor pressure isotope effect in the course of the distillation process, distinguishing it from and extending previously published measurements. The separation factor as a quantitative measure of the vapor pressure isotope effect is found to assume values of 1.04 ± 0.036, 1.05 ± 0.026, and 1.07 ± 0.038, depending on the vigor of the boiling process during distillation of the sample. A lower heat setting in the experimental setup, and therefore a less vigorous boiling process, results in a larger value for the separation factor. For a tritium measurement in water samples where the first 5 mL are discarded, the tritium concentration could be underestimated by 4-7%. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Measurement and analysis of the concentration and size distribution of aerosols in a copper mine

    International Nuclear Information System (INIS)

    Li Dehong; Zhuo Weihai; Huang Gang; Su Xu; Sun Quanfu

    2008-01-01

    Objective: To explore the general characteristics of the concentration and size distribution of aerosols in a mine. Methods: In different areas of a non-uranium mine, the particle number and mass concentration of aerosols were surveyed with a condensation particle counter and a personal aerosol monitor, respectively, and the size distribution of aerosols larger than 1 μm in size was estimated according to the size- selective measurements of mass concentrations. The size distribution of submicron aerosols was evaluated based on the method of screen diffusion battery (SOB), and the measurements were performed in both inside and outside of a control room. Results: The mass concentration of inhaled particles (PM10) was averaged to be 0.42 mg/m 3 in the whole mine, and it varied with different working areas and significantly affected with human activities. In the mine, particles lager than 1 μm in size widely distributed, while the particles less than 5 nm in size were seldom observed. Conclusions: The characteristics of aerosol significantly change with different working areas, human activities and Antilation condition in mine. The dose contribution from inhaled radioactive particles larger than 1 μm in size should be considered in mine. (authors)

  16. The use of neutron activation analysis for particle size fractionation and chemical characterization of trace elements in urban air particulate matter

    International Nuclear Information System (INIS)

    Rizzio, E.; Bergamaschi, G.; Profumo, A.; Gallorini, M.

    2001-01-01

    The concentration of more than 25 trace elements have been determined in total air particulate matter and in the size segregated fractions from the urban area of Pavia (North Italy). The PM10 fraction was also collected and analyzed. A study of the solubility in water and in physiological solution of the trace elements contained in the PM10 was also carried out. The resulting solutions were further submitted to column chromatography using Chelex 100 to perform a preliminary chemical characterization. INAA was used as the main analytical technique. ET-AAS was used for all Pb and Cd measurements and, in some cases, for the analysis of V, Mn, Cu and Ni. (author)

  17. Control of Surface Mounted Permanent Magnet Motors with Special Application to Fractional-Slot Concentrated Windings

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J.S.

    2005-12-21

    It is well known that the ability of the permanent magnet synchronous machine (PMSM) to operate over a wide constant power speed range (CPSR) is dependent upon the machine inductance [1,2,3,4,5]. Early approaches for extending CPSR operation included adding supplementary inductance in series with the motor [1] and the use of anti-parallel thyristor pairs in series with the motor-phase windings [5]. The increased inductance method is compatible with a voltage-source inverter (VSI) controlled by pulse-width modulation (PWM) which is called the conventional phase advance (CPA) method. The thyristor method has been called the dual mode inverter control (DMIC). Neither of these techniques has met with wide acceptance since they both add cost to the drive system and have not been shown to have an attractive cost/benefit ratio. Recently a method has been developed to use fractional-slot concentrated windings to significantly increase the machine inductance [6]. This latest approach has the potential to make the PMSM compatible with CPA without supplemental external inductance. If the performance of such drive is acceptable, then the method may make the PMSM an attractive option for traction applications requiring a wide CPSR. A 30 pole, 6 kW, 6000 maximum revolutions per minute (rpm) prototype of the fractional-slot PMSM design has been developed [7]. This machine has significantly more inductance than is typical of regular PMSMs. The prototype is to be delivered in late 2005 to the Oak Ridge National Laboratory (ORNL) for testing and development of a suitable controller. In advance of the test/control development effort, ORNL has used the PMSM models developed over a number of previous studies to study the steady-state performance of high-inductance PMSM machines with a view towards control issues. The detailed steady-state model developed includes all motor and inverter-loss mechanisms and will be useful in assessing the performance of the dynamic controller to be

  18. Effect of algal density in bead, bead size and bead concentrations ...

    African Journals Online (AJOL)

    Effect of algal density in bead, bead size and bead concentrations on wastewater nutrient removal. ... African Journal of Biotechnology ... The bioreactor containing algal beads (4 mm diameter) with 1.5 x 106 cells bead-1 (cell stocking) at concentration of 10.66 beads ml-1 wastewater (1:3 bead: wastewater, v/v) achieved ...

  19. Late toxicity of radiotherapy in Hodgkin's disease. The role of fraction size

    Energy Technology Data Exchange (ETDEWEB)

    Cosset, J.M.; Henry-Amar, M.; Girinski, T.; Malaise, E.; Dupouy, N.; Dutreix, J.

    1988-01-01

    From 1972 to 1976 patients were irradiated for Hodgkin's disease using a modified fractionation schedule (3 fractions of 3.3 Gy per week) for operational reasons. From 1964 to 1971 and from 1977 to 1981, a more conventional regimen (4 fractions of 2.5 Gy per week) was used. The rates of the late complications in these two subsets of patients treated with different fractionation schedules at the same total dose of 40 Gy during the same overall time were compared. Mediastinitis was observed in 19% of of the '4x2.5 Gy/week' group versus 56% in the '3x3.3 Gy/week' group. Pericarditis in 0% versus 9%, gastroduodenal ulceration and severe gastritis in 10 versus 21% and small bowel obstruction in 5 versus 8%. When using the linear quadratic model with an ..cap alpha../..beta.. of 2.5 Gy to evaluate the equivalent dose of 40 Gy given in 12 fractions of 3.3 Gy when delivered by fractions of 2.5 Gy, a value of 46.6 Gy is found. This difference of 6.6 Gy in the equivalent doses (for late toxicity) is likely to account for the significant increase of late radiation injuries, such as mediastinitis and pericarditis, in the present study. The local relapse rate was found to be slightly lower in the 3x3.3 Gy group. However, this possible benefit cannot offset the considerable increase of late complications.

  20. Microbial communities in litter and soil - particles size fractionation, C- and N-pools and soil enzymes

    International Nuclear Information System (INIS)

    Stemmer, M.; Gerzabek, M.H.; Pichlmayer, F.; Kandeler, E.

    1995-08-01

    In this study we try to correlate C and N pool investigations to enzyme activities in particle size fractions of soils. Soil incubations in the lab (for one year) simulate two different conventional tillage treatments : (i) soil mixed with maize straw (GSF-mixed) and (ii) soil with maize straw lying on the top (home-mixed). The control soil is incubated without any amendment. The separation of the particle size fractions (2000 - 200 μm, 200 - 63 μm, 63 - 2 μm, 2 - 0.1 μm and 0.1 - 0 μm) is realized by a combination of wet-sieving and centrifugation. To disrupt aggregates we use a defined low-energy ultrasonication, which partly preserves microaggregates. The decomposition of organic C during the incubation can be observed clearly, the small amount of N in the added maize straw complicates the analysis. The isotopic measurements of δ13C and δ15N provide valuable additional informations in this context. Both enzymes, saccharase and xylanase, seem to react in a more sensitive way on the incorporation of the maize litter, than the chemical analysis of the pools. The saccharase activity, which seems to be a sensitive indicator for microbial biomass, shows different behaviour between the mix- and top-treatment. The xylanase activity is mainly located in the coarse sand fraction, this extracellular enzyme might be adsorbed by the particulate organic matter. The transfer of adhering coatings and small particles of the added maize to small sized particles during the fractionation procedure and the 'passive role' of the silt fraction, which could be due to the used method, are nonexpected results. (author)

  1. Characterization of the size-fractionated biomacromolecules: Tracking their role and fate in a membrane bioreactor

    DEFF Research Database (Denmark)

    Meng, Fangang; Zhou, Zhongbo; Ni, Bing-Jie

    2011-01-01

    and nuclear magnetic resonance (NMR) measurements were used to characterize BMM in a membrane bioreactor (MBR) from a chemical perspective. Overall, the BMM in sludge supernatant were mainly present in three fractions: colloidal BMM (BMMc, >0.45 μm), biopolymeric BMM (BMMb, 0.45 μm–100 kDa) and low molecular...

  2. Evolution of size-segregated aerosol mass concentration during the Antarctic summer at Northern Foothills, Victoria Land

    Science.gov (United States)

    Illuminati, Silvia; Bau, Sébastien; Annibaldi, Anna; Mantini, Caterina; Libani, Giulia; Truzzi, Cristina; Scarponi, Giuseppe

    2016-01-01

    Within the framework of the Italian National Programm for Antarctic Research (PNRA), the first direct gravimetric measurements of size-segregated aerosol fractions were carried out at Faraglione Camp, ˜3-km far from the Italian station "M. Zucchelli" (Terra Nova Bay, Ross Sea), during the 2014-2015 austral summer. A six-stage high-volume cascade impactor with size classes between 10 μm and 0.49 μm, and, in parallel, for comparison purposes, a PM10 high-volume sampler (50% cut-off aerodynamic diameter of 10 μm) were used. A 10-day sampling strategy was adopted. Aerosol mass measurements were carried out before and after exposure by using a microbalance specifically designed for the filter weight and placed inside a glove bag in order to maintain stable temperature and humidity conditions during weighing sessions. Measured atmospheric concentrations (referred to the "actual air conditions" of mean temperature of 268 K and mean pressure of 975 hPa) of size-segregated aerosol fractions showed the following values, given as size range, means (interquartile range): Dp range 0.1-1.0 μm) and two coarse modes (CM1 in the range 1.0-3.0 μm, and CM2 in the range 3.0-10 μm). From 50% to 90% of the PM10 mass comes from particles of a size smaller than 1.0 μm. The two coarse modes represented from ˜5% to ˜35% of the PM10, showing opposite seasonal trends (CM1 decreased while CM2 increased). During summer, PM10 mass concentration increased to a maximum of ˜1.6 μg m-3 at mid-December, while in January it decreased to values that are typical of November. Both accumulation and upper super-micron fractions showed a maximum in the same period contributing to the PM10 peak of mid-summer.

  3. Decrease of concentration and colloidal fraction of organic carbon and trace elements in response to the anomalously hot summer 2010 in a humic boreal lake.

    Science.gov (United States)

    Shirokova, L S; Pokrovsky, O S; Moreva, O Yu; Chupakov, A V; Zabelina, S A; Klimov, S I; Shorina, N V; Vorobieva, T Ya

    2013-10-01

    The colloidal distribution and size fractionation of organic carbon (OC), major elements and trace elements (TE) were studied in a seasonally stratified, organic-rich boreal lake, Lake Svyatoe, located in the European subarctic zone (NW Russia, Arkhangelsk region). This study took place over the course of 4 years in both winter and summer periods using an in situ dialysis technique (1 kDa, 10 kDa and 50 kDa) and traditional frontal filtration and ultrafiltration (5, 0.22 and 0.025 μm). We observed a systematic difference in dissolved elements and colloidal fractions between summer and winter periods with the highest proportion of organic and organo-ferric colloids (1 kDa-0.22 μm) observed during winter periods. The anomalously hot summer of 2010 in European Russia produced surface water temperatures of approximately 30°C, which were 10° above the usual summer temperatures and brought about crucial changes in element speciation and size fractionation. In August 2010, the concentration of dissolved organic carbon (DOC) decreased by more than 30% compared to normal period, while the relative proportion of organic colloids decreased from 70-80% to only 20-30% over the full depth of the water column. Similarly, the proportion of colloidal Fe decreased from 90-98% in most summers and winters to approximately 60-70% in August 2010. During this hot summer, measurable and significant (>30% compared to other periods) decreases in the colloidal fractions of Ca, Mg, Sr, Ba, Al, Ti, Ni, As, V, Co, Y, all rare earth elements (REEs), Zr, Hf, Th and U were also observed. In addition, dissolved (organic matter by heterotrophic aerobic bacterioplankton and 3) photo-degradation of DOM and photo-chemical liberation of organic-bound TE. While the first process may have caused significant decreases in the total dissolved concentration of micronutrients (a factor of 2 to 5 for Cr, Mn, Fe, Ni, Cu, Zn and Cd and a factor of >100 for Co), the second and third factors could have brought

  4. The pentane- and toluene-soluble fractions of a petroleum residue and three coal tars by size exclusion chromatography and UV-fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Karaca, F.; Millan-Agorio, M.; Morgan, T.J.; Bull, I.D.; Herod, A.A.; Kandiyoti, R. [University of London Imperial College Science Technology & Medicine, London (United Kingdom). Dept. of Chemical Engineering

    2008-01-15

    A petroleum atmospheric pressure distillate residue and three tars derived from different coals using different severities of thermal treatment were separated into seven fractions using column chromatography on silica and sequential elution by the solvent sequence pentane, toluene, acetonitrile, pyridine, 1-methyl-2-pyrrolidinone (NMP) and water. The fractions from the four extractions have been compared using size exclusion chromatography (SEC) in NMP as eluent and by synchronous ultra-violet-fluorescence (UV-F). This paper concerns the pentane and toluene soluble fractions only since these are the least polar fractions. By SEC, the size of the aromatic molecules increased from the first pentane soluble fractions to the toluene-soluble fractions, with the petroleum residue fractions of larger size than the equivalent fractions from coal liquids. The three coal tars showed significant differences, indicating that temperature of pyrolysis had a significant effect on the molecular size. Synchronous UV-F spectra of the four sets of fractions, in solution in NMP, again showed significant differences between the petroleum residue and the coal tars, as well as amongst the three coal tars. In general, the petroleum residue fractions contained smaller aromatic clusters than the coal liquid fractions. These low-polarity fractions contained material excluded from the column porosity in SEC that was unlikely to consist of aggregates of polar molecules.

  5. Influence of the size of facets on point focus solar concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Riveros-Rosas, David [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Col. Copilco, Coyoacan, CP 04510 DF (Mexico); Sanchez-Gonzalez, Marcelino [Centro Nacional de Energias Renovables, c/Somera 7-9, CP 28026 Madrid (Spain); Arancibia-Bulnes, Camilo A.; Estrada, Claudio A. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Priv. Xochicalco s/n, Morelos (Mexico)

    2011-03-15

    It is a common practice in the development of point focus solar concentrators to use multiple identical reflecting facets, as a practical and economic alternative for the design and construction of large systems. This kind of systems behaves in a different manner than continuous paraboloidal concentrators. A theoretical study is carried out to understand the effect of the size of facets and of their optical errors in multiple facet point focus solar concentrating systems. For this purpose, a ray tracing program was developed based on the convolution technique, in which the brightness distribution of the sun and the optical errors of the reflecting surfaces are considered. The study shows that both the peak of concentration and the optimal focal distance of the system strongly depend on the size of the facets, and on their optical errors. These results are useful to help concentrator developers to have a better understanding of the relationship between manufacturing design restrictions and final optical behavior. (author)

  6. Low PIP2 molar fractions induce nanometer size clustering in giant unilamellar vesicles containing POPC

    DEFF Research Database (Denmark)

    Salvemini, Iyrri; Gaua, D.; Reid, J.

    2014-01-01

    generalized polarization function (GP) with unlabeled PIP2 and single point fluorescence correlation spectroscopy and brightness analysis of various BODIPY labeled PIP2 to determine the presence of clusters in the membrane of giant unilamellar vesicles (GUVs) made of 1-palmitoyl-2-oleoyl-sn-glycero-3......-phosphocholine (POPC) or a mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), sphingomyelin and cholesterol. We determined the number of freely diffusing fluorescent BODIPY molecules in the membrane and found that in GUVs containing various amounts of labeled PIP2, this number was significantly lower...... than in GUVs made with the control BODIPY labeled hexadecyl phosphatidylcholine (BODIPY-HPC). Also, we noted an increase in brightness of the labeled PIP2 particles with increasing labeled PIP2 molar fraction. Together with the observed change in LAURDAN GP with increasing molar fraction of unlabeled...

  7. Size distribution and concentrations of heavy metals in atmospheric aerosols originating from industrial emissions as predicted by the HYSPLIT model

    Science.gov (United States)

    Chen, Bing; Stein, Ariel F.; Maldonado, Pabla Guerrero; Sanchez de la Campa, Ana M.; Gonzalez-Castanedo, Yolanda; Castell, Nuria; de la Rosa, Jesus D.

    2013-06-01

    This study presents a description of the emission, transport, dispersion, and deposition of heavy metals contained in atmospheric aerosols emitted from a large industrial complex in southern Spain using the HYSPLIT model coupled with high- (MM5) and low-resolution (GDAS) meteorological simulations. The dispersion model was configured to simulate eight size fractions (17 μm) of metals based on direct measurements taken at the industrial emission stacks. Twelve stacks in four plants were studied and the stacks showed considerable differences for both emission fluxes and size ranges of metals. We model the dispersion of six major metals; Cr, Co, Ni, La, Zn, and Mo, which represent 77% of the total mass of the 43 measured elements. The prediction shows that the modeled industrial emissions produce an enrichment of heavy metals by a factor of 2-5 for local receptor sites when compared to urban and rural background areas in Spain. The HYSPLIT predictions based on the meteorological fields from MM5 show reasonable consistence with the temporal evolution of concentrations of Cr, Co, and Ni observed at three sites downwind of the industrial area. The magnitude of concentrations of metals at two receptors was underestimated for both MM5 (by a factor of 2-3) and GDAS (by a factor of 4-5) meteorological runs. The model prediction shows that heavy metal pollution from industrial emissions in this area is dominated by the ultra-fine (<0.66 μm) and fine (<2.5 μm) size fractions.

  8. Impact of Fraction Size on Lung Radiation Toxicity: Hypofractionation may be Beneficial in Dose Escalation of Radiotherapy for Lung Cancers

    International Nuclear Information System (INIS)

    Jin Jinyue; Kong Fengming; Chetty, Indrin J.; Ajlouni, Munther; Ryu, Samuel; Ten Haken, Randall; Movsas, Benjamin

    2010-01-01

    Purpose: To assess how fraction size impacts lung radiation toxicity and therapeutic ratio in treatment of lung cancers. Methods and Materials: The relative damaged volume (RDV) of lung was used as the endpoint in the comparison of various fractionation schemes with the same normalized total dose (NTD) to the tumor. The RDV was computed from the biologically corrected lung dose-volume histogram (DVH), with an α/β ratio of 3 and 10 for lung and tumor, respectively. Two different (linear and S-shaped) local dose-effect models that incorporated the concept of a threshold dose effect with a single parameter D L50 (dose at 50% local dose effect) were used to convert the DVH into the RDV. The comparison was conducted using four representative DVHs at different NTD and D L50 values. Results: The RDV decreased with increasing dose/fraction when the NTD was larger than a critical dose (D CR ) and increased when the NTD was less than D CR . The D CR was 32-50 Gy and 58-87 Gy for a small tumor (11 cm 3 ) for the linear and S-shaped local dose-effect models, respectively, when D L50 was 20-30 Gy. The D CR was 66-97 Gy and 66-99 Gy, respectively, for a large tumor (266 cm 3 ). Hypofractionation was preferred for small tumors and higher NTDs, and conventional fractionation was better for large tumors and lower NTDs. Hypofractionation might be beneficial for intermediate-sized tumors when NTD = 80-90 Gy, especially if the D L50 is small (20 Gy). Conclusion: This computational study demonstrated that hypofractionated stereotactic body radiotherapy is a better regimen than conventional fractionation in lung cancer patients with small tumors and high doses, because it generates lower RDV when the tumor NTD is kept unchanged.

  9. Power law relation between particle concentrations and their sizes in the blood plasma

    International Nuclear Information System (INIS)

    Kirichenko, M N; Chaikov, L L; Zaritskii, A R

    2016-01-01

    This work is devoted to the investigation of sizes and concentrations of particles in blood plasma by dynamic light scattering (DLS). Blood plasma contains many different proteins and their aggregates, microparticles and vesicles. Their sizes, concentrations and shapes can give information about donor's health. Our DLS study of blood plasma reveals unexpected dependence: with increasing of the particle sizes r (from 1 nm up to 1 μm), their concentrations decrease as r -4 (almost by 12 orders). We found also that such dependence was repeated for model solution of fibrinogen and thrombin with power coefficient is -3,6. We believe that this relation is a fundamental law of nature that shows interaction of proteins (and other substances) in biological liquids. (paper)

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

    Science.gov (United States)

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

    2014-09-01

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

  11. Trends in size classified particle number concentration in subtropical Brisbane, Australia, based on a 5 year study

    Science.gov (United States)

    Mejía, J. F.; Wraith, D.; Mengersen, K.; Morawska, L.

    Particle number size distribution data in the range from 0.015 to 0.630 μm were collected over a 5-year period in the central business district (CBD) of Brisbane, Australia. Particle size distribution was summarised by total number concentration and number median diameter (NMD) as well as the number concentration of the 0.015-0.030 ( N15-30), 0.030-0.050 ( N30-50), 0.050-0.100 ( N50-100), 0.100-0.300 ( N100-300) and 0.300-0.630 ( N300-630) μm size classes. Morning (6:00-10:00) and afternoon (16:00-19:00) measurements, the former representing fresh traffic emissions (based on the local meteorological conditions) and the latter well-mixed emissions from the CBD, during weekdays were extracted and the respective monthly mean values were estimated for time series analysis. For all size fractions, average morning concentrations were about 1.5 higher than in the afternoon whereas NMD did not vary between the morning and afternoon. The trend and seasonal components were extracted through weighted linear regression models, using the monthly variance as weights. Only the morning measurements exhibited significant trends. During this time of the day, total particle number increased by 105.7% and the increase was greater for larger particles, resulting in a shift in NMD by 7.9%. Although no seasonal component was detected the evidence against it remained weak due to the limitations of the database.

  12. Size, Leverage, Concentration, and R&D Investment in Generating Growth Opportunities

    OpenAIRE

    Yew Kee Ho; Mira Tjahjapranata; Chee Meng Yap

    2006-01-01

    We show that a firm's ability to reap growth opportunities from R&D investments depends on its size, leverage, and the industry concentration. While the direct effects of these factors are significant, the size-leverage interaction reveals further important insights. Large firms' advantages over small firms disappear as their leverage increases. Specifically, small firms with high leverage reap the greatest growth opportunities. Our results provide explanations for inconsistent findings obser...

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

    International Nuclear Information System (INIS)

    Zaki, S. S. O.; Ibrahim, M. N.; Katas, H.

    2015-01-01

    Chitosan nanoparticles (CSNPs) have been extensively applied in medical and pharmaceutical fields as promising drug delivery systems. Despite that, the safety of CSNPs remains inadequate and needs further investigation, particularly on hematopoietic stem cells (HSCs). CSNPs were prepared by ionic gelation method and later were characterized for their physical characteristics (particle size and zeta potential). Cytotoxicity of CSNPs was assessed by MTT assay. Particle size was highly influenced by chitosan concentration and molecular weight (medium and high molecular weight (MMW and HMW)). Higher chitosan concentration and molecular weight produced larger nanoparticles. Zeta potential of CSNPs was not significantly affected by chitosan concentrations and molecular weights used in the present study. MMW had a better stability than HMW CSNPs as their particle size and zeta potential were not significantly altered after autoclaving. Cytotoxicity of CSNPs was influenced by zeta potential and particle size. On the other hand, chitosan concentration and molecular weight indirectly influenced cytotoxicity by affecting particle size and zeta potential of CSNPs. In conclusion, cytotoxicity of CSNPs was mainly attributed to their physical characteristics and this opens a strategy to ensure the safety of CSNPs applications in stem cell technology.

  14. Characterization of carbonaceous materials in PM2.5 and PM10 size fractions in Morogoro, Tanzania, during 2006 wet season campaign

    International Nuclear Information System (INIS)

    Mkoma, Stelyus L.; Chi Xuguang; Maenhaut, Willy

    2010-01-01

    Atmospheric aerosol samples in PM10 and PM2.5 size fractions were collected in parallel at a rural site in Morogoro during wet season in March and April 2006. All samples were analysed for the particulate matter mass, for organic, elemental, and total carbon (OC, EC, and TC), and for water-soluble OC (WSOC). The average PM10 and PM2.5 mass concentrations and associated standard deviations were 14 ± 13 μg/m 3 and 7.3 ± 4 μg/m 3 respectively. On average, TC accounted for 33% of the PM10 mass and 44% of the PM2.5 mass for the campaign. The average OC/PM percentage ratios were 27% and 33% in PM10 and PM2.5 size fractions respectively and a larger fraction of the OC was water-soluble. The observed low EC/TC mean percentage ratios of 10-14% respectively for PM10 and PM2.5 fractions indicate that the carbonaceous aerosol originates mainly from biogenic aerosols and/or biomass burning. A simple source apportionment approach was used to apportion the OC to biofuel and charcoal burning. On average, 93% of the PM10 OC was attributed to biofuel and 7% to charcoal burning in the 2006 wet season campaign. However, it is suggested that a contribution to the OC at Morogoro could also come from other natural biogenic matter, and/or biomass burning aerosols. The results for the sources of OC at Morogoro should therefore be considered with great caution.

  15. Obese Hypertensive Men Have Lower Circulating Proatrial Natriuretic Peptide Concentrations Despite Greater Left Atrial Size

    DEFF Research Database (Denmark)

    Asferg, Camilla L; Andersen, Ulrik B; Linneberg, Allan

    2018-01-01

    BACKGROUND: Obese persons have lower circulating natriuretic peptide (NP) concentrations. It has been proposed that this natriuretic handicap plays a role in obesity-related hypertension. In contrast, hypertensive patients with left atrial enlargement have higher circulating NP concentrations....... On this background, we investigated whether obese hypertensive men could have lower circulating NP concentrations despite evidence of pressure-induced greater left atrial size. METHODS: We examined 98 obese men (body mass index [BMI] ≥ 30.0 kg/m2) and 27 lean normotensive men (BMI 20.0-24.9 kg/m2). All men were...... using echocardiography, and we measured fasting serum concentrations of midregional proatrial NP (MR-proANP). RESULTS: Of the 98 obese men, 62 had hypertension and 36 were normotensive. The obese hypertensive men had greater left atrial size (mean ± SD: 28.7 ± 6.0 ml/m2) compared with the lean...

  16. Improving enrichment of circulating fetal DNA for genetic testing: size fractionation followed by whole gene amplification.

    Science.gov (United States)

    Jorgez, Carolina J; Bischoff, Farideh Z

    2009-01-01

    Among the pitfalls of using cell-free fetal DNA in plasma for prenatal diagnosis is quality of the recovered DNA fragments and concomitant presence of maternal DNA (>95%). Our objective is to provide alternative methods for achieving enrichment and high-quality fetal DNA from plasma. Cell-free DNA from 31 pregnant women and 18 controls (10 males and 8 females) were size separated using agarose gel electrophoresis. DNA fragments of 100-300, 500-700 and 1,500-2,000 bp were excised and extracted, followed by whole genome amplification (WGA) of recovered fragments. Levels of beta-globin and DYS1 were measured. Distribution of beta-globin size fragments was similar among pregnant women and controls. Among control male cases, distribution of size fragments was the same for both beta-globin and DYS1. Among maternal cases confirmed to be male, the smallest size fragment (100-300 bp) accounted for nearly 50% (39.76 +/- 17.55%) of the recovered DYS1-DNA (fetal) and only 10% (10.40 +/- 6.49%) of beta-globin (total) DNA. After WGA of plasma fragments from pregnant women, DYS1 sequence amplification was best observed when using the 100-300 bp fragments as template. Combination of electrophoresis for size separation and WGA led to enriched fetal DNA from plasma. This novel combination of strategies is more likely to permit universal clinical applications of cell-free fetal DNA. Copyright 2009 S. Karger AG, Basel.

  17. The distribution feature of size-fractionated chlorophyll a and primary productivity in Prydz Bay and its north sea area during the austral summer

    Institute of Scientific and Technical Information of China (English)

    刘子琳; 陈忠元

    2003-01-01

    The investigation of size-fractionated chlorophyll a and primary productivity were carried out in three longitudinal sections (63°-69°12′S, 70°30′E, 73°E and 75(30′E) at December 18 -26, 1998 and January 12 -18, 1999 in Prydz Bay and its north sea area, Antarctica. The results showed that surface chlorophyll a concentration were 0.16 - 3.99 μg dm -3. The high values of chlorophyll a concentration ( more than 3.5 μg dm -3 ) were in Prydz Bay and in the west Ladies Bank. The average chlorophyll a concentration at sub-surface layer was higher than that at surface layer; its concentration at the deeper layers of 50 m decreased with increasing depth and that at 200 m depth was only 0.01 -0.95 μg dm-3. The results of size-fractionated chlorophyll a showed that the contribution of the netplanktion to total chlorophyll a was 56% , those of the nanoplankton and the picoplankton were 24% and 20% respectively in the surveyed area. The potential primary productivity at the euphotic zone in the surveyed area was 0. 11 - 11.67 mgC m-3 h -1 and average value was 2.00 ±2.80 mgC m-3h-1. The in-situ productivity in the bay and the continental shelf was higher and that in the deep-sea area was lower. The assimilation number of ted primary productivity show that the contribution of the netplanktion to total productivity was 58% , those of the nanoplankton and the picoplankton were 26% and 16% respectively. The cell abundance of phytoplankton was 1. 6 + 103 - 164. 8 + 103 cell dm-3 in the surface water.

  18. Study of Bubble Size, Void Fraction, and Mass Transport in a Bubble Column under High Amplitude Vibration

    Directory of Open Access Journals (Sweden)

    Shahrouz Mohagheghian

    2018-04-01

    Full Text Available Vertical vibration is known to cause bubble breakup, clustering and retardation in gas-liquid systems. In a bubble column, vibration increases the mass transfer ratio by increasing the residence time and phase interfacial area through introducing kinetic buoyancy force (Bjerknes effect and bubble breakup. Previous studies have explored the effect of vibration frequency (f, but minimal effort has focused on the effect of amplitude (A on mass transfer intensification. Thus, the current work experimentally examines bubble size, void fraction, and mass transfer in a bubble column under relatively high amplitude vibration (1.5 mm < A <9.5 mm over a frequency range of 7.5–22.5 Hz. Results of the present work were compared with past studies. The maximum stable bubble size under vibration was scaled using Hinze theory for breakage. Results of this work indicate that vibration frequency exhibits local maxima in both mass transfer and void fraction. Moreover, an optimum amplitude that is independent of vibration frequency was found for mass transfer enhancements. Finally, this work suggests physics-based models to predict void fraction and mass transfer in a vibrating bubble column.

  19. Size exclusion chromatography with online ICP-MS enables molecular weight fractionation of dissolved phosphorus species in water samples.

    Science.gov (United States)

    Venkatesan, Arjun K; Gan, Wenhui; Ashani, Harsh; Herckes, Pierre; Westerhoff, Paul

    2018-04-15

    Phosphorus (P) is an important and often limiting element in terrestrial and aquatic ecosystem. A lack of understanding of its distribution and structures in the environment limits the design of effective P mitigation and recovery approaches. Here we developed a robust method employing size exclusion chromatography (SEC) coupled to an ICP-MS to determine the molecular weight (MW) distribution of P in environmental samples. The most abundant fraction of P varied widely in different environmental samples: (i) orthophosphate was the dominant fraction (93-100%) in one lake, two aerosols and DOC isolate samples, (ii) species of 400-600 Da range were abundant (74-100%) in two surface waters, and (iii) species of 150-350 Da range were abundant in wastewater effluents. SEC-DOC of the aqueous samples using a similar SEC column showed overlapping peaks for the 400-600 Da species in two surface waters, and for >20 kDa species in the effluents, suggesting that these fractions are likely associated with organic matter. The MW resolution and performance of SEC-ICP-MS agreed well with the time integrated results obtained using conventional ultrafiltration method. Results show that SEC in combination with ICP-MS and DOC has the potential to be a powerful and easy-to-use method in identifying unknown fractions of P in the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Influence of soil mercury concentration and fraction on bioaccumulation process of inorganic mercury and methylmercury in rice (Oryza sativa L.).

    Science.gov (United States)

    Zhou, Jun; Liu, Hongyan; Du, Buyun; Shang, Lihai; Yang, Junbo; Wang, Yusheng

    2015-04-01

    Recent studies showed that rice is the major pathway for methylmercury (MeHg) exposure to inhabitants in mercury (Hg) mining areas in China. There is, therefore, a concern regarding accumulation of Hg in rice grown in soils with high Hg concentrations. A soil pot experimental study was conducted to investigate the effects of Hg-contaminated soil on the growth of rice and uptake and speciation of Hg in the rice. Our results imply that the growth of rice promotes residual fraction of Hg transforming to organic-bound fraction in soil and increased the potential risks of MeHg production. Bioaccumulation factors deceased for IHg but relatively stabilized for MeHg with soil total mercury (THg) increasing. IHg in soil was the major source of Hg in the root and stalk, but leaf was contributed by Hg from both atmosphere and soil. Soluble and exchangeable Hg fraction can predict the bioavailability of IHg and MeHg in soils, and that can provide quantitative description of the rate of uptake of the bioavailable Hg. Soluble and exchangeable Hg fraction in paddy soil exceeding 0.0087 mg kg(-1) may cause THg concentration in rice grain above the permissible limit standard, and MeHg concentration in paddy soil more than 0.0091 mg kg(-1) may have the health risks to humans.

  1. Nitrogen uptake by size-fractionated plankton in permanently well-mixed temperate coastal waters

    Digital Repository Service at National Institute of Oceanography (India)

    Wafar, M.V.M.; L'Helguen, S.; Raikar, V.; Maguernd, J.-F.; Le Corre, P.

    ’absorption de l’azote dans un syste`me brasse´ peu profound (Manche occidentale). Oceanol. Acta., 19, 529–537. Malone, T. C. (1980) Algal size. In Morris, I. (ed.), The Physiological Ecology of Phytoplankton. Blackwell, Oxford, UK, 433–463. Platt, T. and Li, W...

  2. Carbohydrates in size fractionated dissolved organic matter in a station of the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, L.; DeSouza, F.; Bhosle, N.B.

    between size and diagenetic state of organic matter. Materials and Methods Seawater samples were collected on 12th August 2001 from four discrete depths (2 m, 100 m, 500 m, and 1000 m) using Niskin water samplers (30 liter) attached to the CTD...

  3. Size fraction assaying of gold bearing rocks (for gold extraction) by ...

    African Journals Online (AJOL)

    A novel method has been developed for processing and extraction of gold from gold bearing rocks for use by small-scale gold miners in Ghana. The methodology involved crushing of gold bearing hard rocks to fine particles to form a composite sample and screening at a range of sizes. Gold distribution in the composite ...

  4. Distribution, diversity and abundance of bacterial laccase-like genes in different particle size fractions of sediments in a subtropical mangrove ecosystem.

    Science.gov (United States)

    Luo, Ling; Zhou, Zhi-Chao; Gu, Ji-Dong

    2015-10-01

    This study investigated the diversity and abundance of bacterial lacasse-like genes in different particle size fractions, namely sand, silt, and clay of sediments in a subtropical mangrove ecosystem. Moreover, the effects of nutrient conditions on bacterial laccase-like communities as well as the correlation between nutrients and, both the abundance and diversity indices of laccase-like bacteria in particle size fractions were also studied. Compared to bulk sediments, Bacteroidetes, Caldithrix, Cyanobacteria and Chloroflexi were dominated in all 3 particle-size fractions of intertidal sediment (IZ), but Actinobacteria and Firmicutes were lost after the fractionation procedures used. The diversity index of IZ fractions decreased in the order of bulk > clay > silt > sand. In fractions of mangrove forest sediment (MG), Verrucomicrobia was found in silt, and both Actinobacteria and Bacteroidetes appeared in clay, but no new species were found in sand. The declining order of diversity index in MG fractions was clay > silt > sand > bulk. Furthermore, the abundance of lacasse-like bacteria varied with different particle-size fractions significantly (p clay > silt in both IZ and MG fractions. Additionally, nutrient availability was found to significantly affect the diversity and community structure of laccase-like bacteria (p fractions (p < 0.05). Therefore, this study further provides evidence that bacterial laccase plays a vital role in turnover of sediment organic matter and cycling of nutrients.

  5. Effect of algal density in bead, bead size and bead concentrations ...

    African Journals Online (AJOL)

    Laboratory experiments were performed to study nitrogen and phosphorus uptake by the unicellular green microalga Chlorella vulgaris immobilized in calcium alginate beads. Different cell stockings in beads, different bead sizes and different algal bead concentrations in wastewaters were tested. Significant higher nutrients ...

  6. [Carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand land.

    Science.gov (United States)

    Ma, Jian Ye; Tong, Xiao Gang; Li, Zhan Bin; Fu, Guang Jun; Li, Jiao; Hasier

    2016-11-18

    The aim of this study was to investigate the effects of carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand Land, soil samples were collected from quicksand land, semifixed sand and fixed sand lands that were established by the shrub for 20-55 year-old and the arbor for 20-50 year-old at sand control region of Yulin in Northern Shaanxi Province. The dynamics and sequestration rate of soil organic carbon (SOC) associated with sand, silt and clay were measured by physical fractionation method. The results indicated that, compared with quicksand area, the carbon content in total SOC and all soil particle-sized fractions at bothsand-fixing sand forest lands showed a significant increasing trend, and the maximum carbon content was observed in the top layer of soils. From quicksand to fixed sand land with 55-year-old shrub and 50-year-old arbor, the annual sequestration rate of carbon stock in 0-5 cm soil depth was same in silt by 0.05 Mg·hm -2 ·a -1 . The increase rate of carbon sequestration in sand was 0.05 and 0.08 Mg·hm -2 ·a -1 , and in clay was 0.02 and 0.03 Mg·hm -2 ·a -1 at shrubs and arbors land, respectively. The increase rate of carbon sequestration in 0-20 cm soil layer for all the soil particles was averagely 2.1 times as that of 0-5 cm. At the annual increase rate of carbon, the stock of carbon in sand, silt and clay at the two fixed sand lands were increased by 6.7, 18.1 and 4.4 times after 50-55 year-old reversion of quicksand land to fixed sand. In addition, the average percentages that contributed to accumulation of total SOC by different particles in 0-20 cm soil were in the order of silt carbon (39.7%)≈sand carbon (34.6%) > clay carbon (25.6%). Generally, the soil particle-sized fractions had great carbon sequestration potential during reversion of desertification in Mu Us Sand Land, and the slit and sand were the main fractions for carbon sequestration at both fixed sand lands.

  7. The fractionation and geochemical characteristics of rare earth elements measured in ambient size-resolved PM in an integrated iron and steelmaking industry zone.

    Science.gov (United States)

    Dai, Qili; Li, Liwei; Yang, Jiamei; Liu, Baoshuang; Bi, Xiaohui; Wu, Jianhui; Zhang, YuFen; Yao, Lin; Feng, Yinchang

    2016-09-01

    Improved understanding of the fractionation and geochemical characteristic of rare earth elements (REEs) from steel plant emissions is important due to the unclear atmospheric signature of these elements and their adverse impact on human health and the environment. In this study, ambient particulate matter of different sizes was collected from one site in an integrated iron and steelmaking industrial zone (HG) and one urban background site with no direct industrial emissions (ZWY) during a 1-year sampling campaign in China. The total concentrations of REEs for TSP, PM10, and PM2.5 were 27.248, 14.989, 3.542 ng/m(3) in HG and 6.326, 5.274, 1.731 ng/m(3), respectively, in ZWY, which revealed the local influence of the steelmaking activities to the air quality. With respect to ZWY, the REEs in HG site are obviously fractionated in the coarser fraction, and LREEs account for more than 80 % of the total REE burden in all of the samples. Additionally, the REEs in HG and ZWY show a homogeneous trend with successively increased LREE/HREE ratios from the coarse particles to the fine particles. In our samples, La, Ce, Nd, and Sm are the most enriched rare earth elements, especially in the HG site. Moreover, ternary diagrams of LaCeSm indicate that the REEs in HG are potentially contributed by steelworks, carrier vehicles, coal combustion, and road dust re-suspension.

  8. Impact of Fraction Size on Cardiac Mortality in Women Treated With Tangential Radiotherapy for Localized Breast Cancer

    International Nuclear Information System (INIS)

    Marhin, Wilson; Wai, Elaine; Tyldesley, Scott

    2007-01-01

    Purpose: To determine whether fraction size affects the risk of cardiac mortality in women treated with adjuvant radiotherapy (RT) for left-sided breast cancer. Methods and Materials: A population-based retrospective study of women with a diagnosis of localized breast cancer treated with adjuvant RT in British Columbia from 1984 to 2000. Cases were identified from the British Columbia Cancer Agency database. Overall and cardiac-specific survival were compared for women treated with RT for left- vs. right-sided breast cancer. We analyzed the impact of age (≤60 vs. >60 years) at diagnosis and RT fraction size (≤2 vs. >2 Gy) on risk of fatal cardiac events. Results: We identified 3,781 women with left-sided and 3,666 women with right-sided breast cancer who received adjuvant RT. Median follow-up was 7.9 years. There were 52 vs. 47 breast cancer deaths in women treated for left- and right-sided breast cancer, respectively. There was no significant difference in cardiac mortality for women ≤60 or >60 years of age who received adjuvant RT for left-sided vs. right-sided cancer. There was no difference in cardiac mortality for women who received adjuvant RT with fraction sizes ≤2 vs. >2 Gy for left- or right-sided cancer. Conclusions: There was no evidence for increased risk of cardiac mortality in women treated with adjuvant RT after a median follow-up of 7.9 years in our cohort. Hypofractionated adjuvant RT regimens did not significantly increase the risk of cardiac mortality

  9. Effect of size and concentration of silt particles on erosion of Pelton turbine buckets

    Energy Technology Data Exchange (ETDEWEB)

    Padhy, M.K.; Saini, R.P. [Alternate Hydro Energy Centre, Indian Institute of Technology Roorkee, Roorkee (India)

    2009-10-15

    Erosive wear of hydro turbine runners depends upon different parameters such as size, hardness and concentration of silt particles, velocity of flow, properties of the base material of the turbine components and operating hours of the turbine. Various researchers have conducted experiments to study the effect of these parameters on erosive wear. Most of these experiments were on small-size samples at different types of test rigs to simulate the flow conditions in turbines, however actual flow conditions and the phenomenon of erosive wear are too complex to simulate. Under the present study, effect of these parameters on erosion in actual conditions has been investigated experimentally. An extensive experimental study has been carried out on a small scale Pelton turbine. Based on the experimental data collected for different parameters, correlations have been developed for wear rate of Pelton turbine buckets as a function of critical parameters, i.e., size and concentration of silt particles and jet velocity. (author)

  10. Particle number concentration, size distribution and chemical composition during haze and photochemical smog episodes in Shanghai.

    Science.gov (United States)

    Wang, Xuemei; Chen, Jianmin; Cheng, Tiantao; Zhang, Renyi; Wang, Xinming

    2014-09-01

    The aerosol number concentration and size distribution as well as size-resolved particle chemical composition were measured during haze and photochemical smog episodes in Shanghai in 2009. The number of haze days accounted for 43%, of which 30% was severe (visibilitysmog episodes, about 5.89 times and 4.29 times those of clean days. The particle volume concentration and surface concentration in haze, photochemical smog and clean days were 102, 49, 15μm(3)/cm(3) and 949, 649, 206μm(2)/cm(3), respectively. As haze events got more severe, the number concentration of particles smaller than 50nm decreased, but the particles of 50-200nm and 0.5-1μm increased. The diurnal variation of particle number concentration showed a bimodal pattern in haze days. All soluble ions were increased during haze events, of which NH4(+), SO4(2-) and NO3(-) increased greatly, followed by Na(+), K(+), Ca(2+) and Cl(-). These ions were very different in size-resolved particles during haze and photochemical smog episodes. Copyright © 2014. Published by Elsevier B.V.

  11. Influence of left ventricular hypertrophy on infarct size and left ventricular ejection fraction in ST-elevation myocardial infarction

    International Nuclear Information System (INIS)

    Małek, Łukasz A.; Śpiewak, Mateusz; Kłopotowski, Mariusz; Petryka, Joanna; Mazurkiewicz, Łukasz; Kruk, Mariusz; Kępka, Cezary; Miśko, Jolanta; Rużyłło, Witold; Witkowski, Adam

    2012-01-01

    Background: Left ventricular hypertrophy (LVH) predisposes to larger infarct size, which may be underestimated by the left ventricular ejection fraction (LVEF) due to supranormal systolic performance often present in patients with LVH. The aim of the study was to compare infarct size and LVEF in patients with ST-segment elevation myocardial infarction (STEMI) and increased left ventricular mass on cardiac magnetic resonance (CMR). Methods: The study included unselected group of 52 patients (61 ± 11 years, 69% male) with first STEMI who had CMR after median 5 days from the onset of the event. Left ventricular hypertrophy (LVH) was defined as left ventricular mass index exceeding 95th percentile of references values for age and gender. Infarct size was assessed with means of late gadolinium enhancement (LGE). Results: LVH was found in 16 patients (31%). In comparison to the rest of the group, patients with LVH had higher absolute and relative infarct mass (p = 0.002 and p = 0.02, respectively). LVH was related to higher prevalence of microvascular obstruction and myocardial haemorrhage and higher number of LV segments with transmural necrosis (p = 0.02, p = 0.01 and p = 0.01, respectively). Despite marked difference in the infarct size between both studied subgroups there was no difference in LVEF and mean number of dysfunctional LV segments. Conclusions: Patients with LVH undergoing STEMI have larger infarct size underestimated by the LV systolic performance in comparison to patients without LVH.

  12. Concentrations and size distributions of fine aerosol particles measured at roof level in urban zone

    Science.gov (United States)

    Despiau, S.; Croci, D.

    2007-05-01

    During the experimental Field Experiments to Constrain Models of Atmospheric Pollution and Transport of Emissions (ESCOMPTE) campaign in June-July 2001, concentrations and size distributions of fine particles (14-722 nm) were measured at roof level in downtown Marseille (France). Part of the campaign was dedicated to the study of aerosol behavior in relation to strong photochemical events (which were identified as "IOP" days) and their regional modeling. The analysis of the concentration variations and the evolution of average diurnal size distribution showed that an "IOP day" is not characterized by a specific concentration or its variation, nor by a specific evolution of the average size distribution. The morning traffic rush is detected at roof level by a net increase in particle concentration over the whole size range measured, indicating a production of ultrafine particles by the traffic but also the raising to roof level of particles of the accumulation mode. The increase is observed about 1 hour after the traffic peak at street level, which is characterized by strong increases in NOx and CO concentrations. The corresponding flux of particles at roof level has been estimated around 3 × 104 cm-2 s-1. A specific signature characterized by a strong and rapid burst of concentration (factor 2 to 4 in 15 min) of particles between 25 and 50 nm, independent of the traffic source, has been detected on six occasions during the campaign. These events occur systematically around noon, in cases of strong radiation, low relative humidity, and common wind direction. Despite the high-diameter value of these particles, it is suggested that they could result from a specific "secondary aerosol process" event involving ozone, biogenic, and/or anthropogenic gas precursors like iodine and VOCs.

  13. Effect of surfactant concentration on the size of one-pot synthesized Si nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Su Jung; Kim, Tae Woo; Lee, Myong Euy [Dept. of Chemistry and Medical Chemistry, College of Science and Technology, Research and EducationCenter for Advanced Silicon Materials, Yonsei University, Wonju (Korea, Republic of); Cho, Hyeon Mo [University College, Yonsei University, Incheon (Korea, Republic of); Yoon, Sang Woong [Youngchang Chemical Co., LTD, Seongnam (Korea, Republic of); Ryou, Joon Sung [Advanced Technology R and D Center, SKC, Suwon (Korea, Republic of)

    2015-07-15

    The effect of surfactant concentration on the synthesis of Si nanoparticles (NPs) was studied. Hexyl Si NPs were synthesized using one-pot synthetic methodology with different ratios of SiCl{sub 4}:HexylSiCl{sub 3} (1:1, 1:2, 1:3, 1:6) to observe the effect of surfactant concentration on the size of Si NPs. In Fourier transform infrared spectroscopy analysis, the Si–H stretching band and the characteristic Si–O–Si bands decreased and eventually disappeared with increasing hexyltrichlorosilane concentration. This suggests that the level of oxidation decreased with excess amounts of hexyltrichlorosilane because the surface area of exposed Si NPs without hexyl capping groups was reduced. Results of transmission electron microscopy and particle size analysis showed that the average diameter of hexyl Si NPs increased slightly from low surfactant concentration (SiCl{sub 4}:HexylSiCl{sub 3} = 1:1) to high concentration (1:6). This might be caused due to the relationship between the surfactant concentration effect and the core material part effect of hexyltrichlorosilane. Agglomerated Si NPs were observed and their luminescence bands were not shifted because the Si NPs were capped by alkyl groups to prevent aggregation.

  14. Size distributions of hydrophilic and hydrophobic fractions of water-soluble organic carbon in an urban atmosphere in Hong Kong

    Science.gov (United States)

    Wang, Nijing; Yu, Jian Zhen

    2017-10-01

    Water-soluble organic carbon (WSOC) is a significant part of ambient aerosol and plays an active role in contributing to aerosol's effect on visibility degradation and radiation budget through its interactions with atmospheric water. Size-segregated aerosol samples in the range of 0.056-18 μm were collected using a ten-stage impactor sampler at an urban site in Hong Kong over one-year period. The WSOC samples were separated into hydrophilic (termed WSOC_h) and hydrophobic fractions (i.e., the humic-like substances (HULIS) fraction) through solid-phase extraction procedure. Carbon in HULIS accounted for 40 ± 14% of WSOC. The size distribution of HULIS was consistently characterized in all seasons with a dominant droplet mode (46-71%) and minor condensation (9.0-18%) and coarse modes (20-35%). The droplet mode had a mass median aerodynamic diameter in the range of 0.7-0.8 μm. This size mode showed the largest seasonal variation in abundance, lowest in the summer (0.41 μg/m3) and highest in the winter (3.3 μg/m3). WSOC_h also had a dominant droplet mode, but was more evenly distributed among different size modes. Inter-species correlations within the same size mode suggest that the condensation-mode HULIS was partly associated with combustion sources and the droplet-mode was strongly associated with secondary sulfate formation and biomass burning particle aging processes. There is evidence to suggest that the coarse-mode HULIS largely originated from coagulation of condensation-mode HULIS with coarse soil/sea salt particles. The formation process and possible sources of WSOC_h was more complicated and multiple than HULIS and need further investigation. Our measurements indicate that WSOC components contributed a dominant fraction of water-soluble aerosol mass in particles smaller than 0.32 μm while roughly 20-30% in the larger particles.

  15. Fractionation of Exosomes and DNA using Size-Based Separation at the Nanoscale

    Science.gov (United States)

    Wunsch, Benjamin; Smith, Joshua; Wang, Chao; Gifford, Stacey; Brink, Markus; Bruce, Robert; Solovitzky, Gustavo; Austin, Robert; Astier, Yann

    Exosomes, a key target of ``liquid biopsies'', are nano-vesicles found in nearly all biological fluids. Exosomes are secreted by eukaryotic and prokaryotic cells alike, and contain information about their originating cells, including surface proteins, cytoplasmic proteins, and nucleic acids. One challenge in studying exosome morphology is the difficulty of sorting exosomes by size and surface markers. Common separation techniques for exosomes include ultracentrifugation and ultrafiltration, for preparation of large volume samples, but these techniques often show contamination and significant heterogeneity between preparations. To date, deterministic lateral displacement (DLD) pillar arrays in silicon have proven an efficient technology to sort, separate, and enrich micron-scale particles including human parasites, eukaryotic cells, blood cells, and circulating tumor cells in blood; however, the DLD technology has never been translated to the true nanoscale, where it could function on bio-colloids such as exosomes. We have fabricated nanoscale DLD (nanoDLD) arrays capable of rapidly sorting colloids down to 20 nm in continuous flow, and demonstrated size sorting of individual exosome vesicles and dsDNA polymers, opening the potential for on-chip biomolecule separation and diagnosti

  16. Concentrations of polycyclic aromatic hydrocarbons in resuspendable fraction of settled bus dust and its implications for human exposure

    International Nuclear Information System (INIS)

    Gao, Peng; Liu, Sa; Feng, Yujie; Lin, Nan; Lu, Binyu; Zhang, Zhaohan; Cui, Fuyi; Xing, Baoshan; Hammond, S. Katharine

    2015-01-01

    This preliminary study measured Polycyclic Aromatic Hydrocarbons (PAHs) concentrations in the resuspendable fraction of settled dust on 39 bus lines, to evaluate the impact of engine type (gasoline and compressed natural gas) on exposure for commuters and drivers. Benzo(b)fluoranthene(BbF) was the predominant PAH in resuspendable fraction of settled bus dust. The concentration of total PAHs was 92.90 ± 116.00 μg/g (range: 0.57–410) in gasoline buses and 3.97 ± 1.81 (range: 2.01–9.47) in compressed natural gas (CNG) buses. Based on Benzo[a]pyrene (BaP) equivalent concentrations for the sum of 16 PAHs, the average daily dose (ADD) via dust ingestion and dermal contact was calculated. The ADD of PAHs was higher for commuters and drivers in gasoline-powered buses than in buses using CNG buses. For both short and long duration journeys, young commuters were exposed to higher levels of PAHs via dust ingestion and dermal contact than adult commuters. - Highlights: • Resuspendable fraction of settled dust from microenvironment of buses in Harbin monitored for PAHs exposure assessment. • Higher levels of PAHs pollutants at gasoline-powered buses than at compressed natural gas-powered buses. • Non-occupational and occupational exposures in the microenvironment of buses are assessed. - Occupational and non-occupational exposure to PAHs from the microenvironment of bus

  17. Separation, fractionation, concentration and drying of food products: Technology progress report, October 1, 1984-March 3, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Rose, W. W.; Pederson, L. D.; Merlo, C. A.; Brewbaker, P. L.

    1987-11-01

    This report describes the first and second phases of a three phase project, the object of which is to develop energy efficient separation, concentration, and drying processes for food products, especially juice products, in order to reduce energy requirements and their associated costs for processing, preservation, and transportation. Presently in juice processing, much water is eliminated through evaporation. However, there are significant limits to the current evaporation technology. If, however, the juice could be separated, prior to evaporation, into liquid and solid fractions, and the liquid concentrated further, the containerization and transportation costs could be significantly reduced. Separation methods investigated in this project are: vacuum filtration, centrifugation, and crossflow microfiltration.

  18. Leaching behavior of U, Mn, Sr, and Pb from different particle-size fractions of uranium mill tailings.

    Science.gov (United States)

    Liu, Bo; Peng, Tongjiang; Sun, Hongjuan

    2017-06-01

    Pollution by the release of heavy metals from tailings constitutes a potential threat to the environment. To characterize the processes governing the release of Mn, Sr, Pb, and U from the uranium mill tailings, a dynamic leaching test was applied for different size of uranium mill tailings samples. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) were performed to determine the content of Mn, Sr, Pb, and U in the leachates. The release of mobile Mn, Sr, Pb, and U fraction was slow, being faster in the initial stage and then attained a near steady-state condition. The experimental results demonstrate that the release of Mn, Sr, Pb, and U from uranium mill tailings with different size fractions is controlled by a variety of mechanisms. Surface wash-off is the release mechanism for Mn. The main release mechanism of Sr and Pb is the dissolution in the initial leaching stage. For U, a mixed process of wash-off and diffusion is the controlling mechanism.

  19. Cs adsorption on the clay-sized fraction of various soils: effect of organic matter destruction and charge compensating cation

    International Nuclear Information System (INIS)

    Staunton, S.; Levacic, P.

    1999-01-01

    The association of organic matter with clay minerals may decrease their affinity for Cs and thus enhance its bioavailability. We have investigated this hypothesis by comparing Cs adsorption on several soils, both topsoils and the corresponding subsoils, before and after organic matter destruction with H 2 O 2 . The clay-sized fractions were homoionic in either K, Na or Ca, to avoid artefacts due to variable composition of the exchange complex. All experiments were carried out in dilute suspension under controlled conditions. The affinity of the clay-sized fractions for Cs and the value of the Freundlich b parameter are typical of illites. This supports the hypothesis that the adsorption properties of soils are dominated by small amounts of illite. However, if this is the case, the affinity of soil illites is higher than that of reference illites. The destruction of organic matter has a variable effect. In some cases, a marked enhancement is observed, in others there is no significant effect, or a small decrease. There is no clear pattern relating the effect of organic matter destruction and either dominant clay mineralogy or organic matter content. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  20. Effect of hyperbaric oxygen therapy combined with autologous platelet concentrate applied in rabbit fibula fraction healing

    Directory of Open Access Journals (Sweden)

    Paulo Cesar Fagundes Neves

    2013-09-01

    Full Text Available OBJECTIVES: The purpose is to study the effects of hyperbaric oxygen therapy and autologous platelet concentrates in healing the fibula bone of rabbits after induced fractures. METHODS: A total of 128 male New Zealand albino rabbits, between 6-8 months old, were subjected to a total osteotomy of the proximal portion of the right fibula. After surgery, the animals were divided into four groups (n = 32 each: control group, in which animals were subjected to osteotomy; autologous platelet concentrate group, in which animals were subjected to osteotomy and autologous platelet concentrate applied at the fracture site; hyperbaric oxygen group, in which animals were subjected to osteotomy and 9 consecutive daily hyperbaric oxygen therapy sessions; and autologous platelet concentrate and hyperbaric oxygen group, in which animals were subjected to osteotomy, autologous platelet concentrate applied at the fracture site, and 9 consecutive daily hyperbaric oxygen therapy sessions. Each group was divided into 4 subgroups according to a pre-determined euthanasia time points: 2, 4, 6, and 8 weeks postoperative. After euthanasia at a specific time point, the fibula containing the osseous callus was prepared histologically and stained with hematoxylin and eosin or picrosirius red. RESULTS: Autologous platelet concentrates and hyperbaric oxygen therapy, applied together or separately, increased the rate of bone healing compared with the control group. CONCLUSION: Hyperbaric oxygen therapy and autologous platelet concentrate combined increased the rate of bone healing in this experimental model.

  1. Surface-enhanced Raman spectroscopy of chernozem humic acid and their fractions obtained by coupled size exclusion chromatography-polyacrylamide gel electrophoresis (SEC-PAGE).

    Science.gov (United States)

    Sanchez-Cortes, S; Corrado, G; Trubetskaya, O E; Trubetskoj, O A; Hermosin, B; Saiz-Jimenez, C

    2006-01-01

    A humic acid extracted from a chernozem soil was fractionated combining size exclusion chromatography and polyacrylamide electrophoresis (SEC-PAGE). Three fractions named A, B, and C+D, with different electrophoretic mobilities and molecular sizes (MS), were obtained and subsequently characterized by thermochemolysis and surface-enhanced Raman spectroscopy (SERS). The data confirmed that fraction A, with the higher MS, was more aliphatic than fractions B and C+D and, in turn, fractions with lower MS (B and C+D) denoted an enrichment in lignin residues. These structural features explain conformational changes when varying the pH in the humic fraction A and indicated that combination of the two techniques is a good approach for characterizing humic substances.

  2. Concentration and Size Distribution of Particulate Matter in a Broiler House Ambient Air

    Directory of Open Access Journals (Sweden)

    Ismael Rodrigues Amador

    2016-07-01

    Full Text Available Atmospheric particulate matter (PM is an important constituent of ambient air. The determination of its concentration and size distribution in different environments is essential because of its ability to penetrate deeply into animal and human respiratory tract. In this study, air sampling was performed in a broiler house to estimate the concentration and size distribution of PM emitted along with its activities. Low-vol impactor (< 10 mm, cyclones (< 2.5 e < 1.0 mm, and Sioutas cascade impactor (> 2.5; 1.0 – 2.5; 0.50 – 1.0; 0.25 – 0.50; < 0.25 mm connected with membrane pumps were used. PM10 showed high concentration (209 - 533 mg m-3. PM2.5 and PM1.0 initially showed relatively low concentration (20.8 and 16.0 mg m-3 respectively with significantly increasing levels (412.9 and 344.8 mg m-3 respectively during the samplings. It was also possible to observe the contribution of fine particles. This was evidenced by the high correlation between PM2.5 and PM1.0 and by the profile of particle distribution in the Sioutas sampler. PM concentration levels are considered excessively high, with great potential to affect animal and human health. DOI: http://dx.doi.org/10.17807/orbital.v8i3.847 

  3. The effects of fluvial transport on radionuclide concentrations on different particle size classes

    International Nuclear Information System (INIS)

    Dyer, F.J.; Olley, J.M.

    1998-01-01

    This paper reports on the effects of grain abrasion and disaggregation on the distribution of 137 Cs with respect to particle size and the effects this may have on the use of 137 Cs for determining the origin of recent sediment. Cs-137 is a product of above ground nuclear testing and has been deposited on the earth's surface by rainfall. On contact with soil, 137 Cs is strongly adsorbed by soil particles and there is a direct correlation between 137 Cs concentration and decreasing particle size. Rapid adsorption means that 137 Cs is preferentially concentrated in surface soils, and it's subsequent redistribution by physical processes rather than chemical has lead to 137 Cs being widely used to study soil erosion

  4. Size, velocity, and concentration in suspension measurements of spherical droplets and cylindrical jets.

    Science.gov (United States)

    Onofri, F; Bergougnoux, L; Firpo, J L; Misguich-Ripault, J

    1999-07-20

    The principle of an optical technique for simultaneous velocity, size, and concentration in suspension measurements of spherical droplets and cylindrical jets is proposed. This technique is based on phase Doppler anemometry working in the dual burst technique configuration. The particle size and velocity are deduced from the reflected signal phase and frequency, whereas the amplitude ratio between the refracted and the reflected signals is used for measuring the concentration of small scatterers inside the particles. Numerical simulations, based on geometrical optics and a Monte Carlo model, and an experimental validation test on cylindrical jets made of various suspensions, are used to validate the principle of the proposed technique. It is believed that this new technique could be useful in investigating processes in which liquid suspensions are sprayed for surface coating, drying, or combustion applications.

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

    International Nuclear Information System (INIS)

    Pickering, S.

    1982-01-01

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

  6. Airstream Fractionation of Vesicular-Arbuscular Mycorrhizal Fungi: Concentration and Enumeration of Propagules

    OpenAIRE

    Tommerup, Inez C.

    1982-01-01

    Spores and fragments of vesicular-arbuscular mycorrhizal fungi in dry soils were concentrated up to 100-fold when the soils were partitioned by fluidization and elutriation with a series of upward airstreams at progressively increasing velocities. The propagules were transported with the finer soil particles according to their equivalent spherical diameters. The system was used to predict the transport of propagules by wind. Concentrated propagules were rapidly separated from the soil particl...

  7. Comparisons of urban and rural PM10−2.5 and PM2.5 mass concentrations and semi-volatile fractions in northeastern Colorado

    Directory of Open Access Journals (Sweden)

    N. Clements

    2016-06-01

    Full Text Available Coarse (PM10−2.5 and fine (PM2.5 particulate matter in the atmosphere adversely affect human health and influence climate. While PM2.5 is relatively well studied, less is known about the sources and fate of PM10−2.5. The Colorado Coarse Rural-Urban Sources and Health (CCRUSH study measured PM10−2.5 and PM2.5 mass concentrations, as well as the fraction of semi-volatile material (SVM in each size regime (SVM2.5, SVM10−2.5, from 2009 to early 2012 in Denver and comparatively rural Greeley, Colorado. Agricultural operations east of Greeley appear to have contributed to the peak PM10−2.5 concentrations there, but concentrations were generally lower in Greeley than in Denver. Traffic-influenced sites in Denver had PM10−2.5 concentrations that averaged from 14.6 to 19.7 µg m−3 and mean PM10−2.5 ∕ PM10 ratios of 0.56 to 0.70, higher than at residential sites in Denver or Greeley. PM10−2.5 concentrations were more temporally variable than PM2.5 concentrations. Concentrations of the two pollutants were not correlated. Spatial correlations of daily averaged PM10−2.5 concentrations ranged from 0.59 to 0.62 for pairs of sites in Denver and from 0.47 to 0.70 between Denver and Greeley. Compared to PM10−2.5, concentrations of PM2.5 were more correlated across sites within Denver and less correlated between Denver and Greeley. PM10−2.5 concentrations were highest during the summer and early fall, while PM2.5 and SVM2.5 concentrations peaked in winter during periodic multi-day inversions. SVM10−2.5 concentrations were low at all sites. Diurnal peaks in PM10−2.5 and PM2.5 concentrations corresponded to morning and afternoon peaks of traffic activity, and were enhanced by boundary layer dynamics. SVM2.5 concentrations peaked around noon on both weekdays and weekends. PM10−2.5 concentrations at sites located near highways generally increased with wind speeds above about 3 m s−1. Little wind speed dependence was

  8. Impact of Chronic Hepatitis C Virus Genotype 1b Infection on Triglyceride Concentration in Serum Lipoprotein Fractions

    Directory of Open Access Journals (Sweden)

    Tomohisa Nagano

    2015-08-01

    Full Text Available Reduced low-density lipoprotein (LDL cholesterol level is a characteristic feature of dyslipidemia in chronic hepatitis C virus (HCV infection. However, abnormality in serum triglyceride (TG has not been fully investigated. To clarify the impact of HCV genotype 1b (G1b infection and advanced fibrosis on serum TG profiles, TG concentrations in lipoprotein fractions were examined in fasting sera from 185 subjects with active or cleared HCV infection by high-performance liquid chromatography. Serum lipoproteins were fractionated into four classes: chylomicron, very low-density lipoprotein (VLDL, LDL, and high-density lipoprotein (HDL. Then, the significance of HCV G1b infection on TG levels in each lipoprotein fraction was determined using multiple regression models. We found that active HCV G1b infection was positively associated with high HDL-TG levels and low VLDL-TG levels, independent of other factors included in the regression model. In VLDL sub-fractions, active HCV infection was only found to be associated with low levels of large VLDL-TG. Similarly, advanced liver fibrosis in chronic HCV G1b infection was associated with high levels of LDL-TG, HDL-TG, and small VLDL-TG, independent of other clinical factors. These findings indicate that active HCV G1b infection and advanced fibrosis are closely associated with abnormal serum TG profiles.

  9. Round-shape gold nanoparticles: effect of particle size and concentration on Arabidopsis thaliana root growth

    Czech Academy of Sciences Publication Activity Database

    Siegel, J.; Záruba, K.; Švorčík, V.; Kroumanová, Kristýna; Burketová, Lenka; Martinec, Jan

    2018-01-01

    Roč. 13, APR 10 (2018), č. článku 95. ISSN 1556-276X R&D Projects: GA ČR GA17-10907S; GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:61389030 Keywords : Arabidopsis thaliana * Concentration * Gold nanoparticles * Root growth * Size Subject RIV: JJ - Other Materials OBOR OECD: Plant sciences, botany Impact factor: 2.833, year: 2016

  10. Effect of particle size distribution and concentration on flow behavior of dense slurries

    Czech Academy of Sciences Publication Activity Database

    Vlasák, Pavel; Chára, Zdeněk

    2011-01-01

    Roč. 29, č. 1 (2011), s. 53-65 ISSN 0272-6351 R&D Projects: GA ČR(CZ) GAP105/10/1574 Institutional research plan: CEZ:AV0Z20600510 Keywords : concentration effect * dense complex slurry * experimental investigation * flow behavior * particle size distribution effect * pressure drop Subject RIV: BK - Fluid Dynamics Impact factor: 0.545, year: 2011

  11. Size-dependent concentration of N0 paramagnetic centres in HPHT nanodiamonds

    OpenAIRE

    Yavkin, Boris V; Mamin, Georgy V; Gafurov, Marat R.; Orlinskii, Sergei B.

    2015-01-01

    Size-calibrated commercial nanodiamonds synthesized by high-pressure high-temperature (HPHT) technique were studied by high-frequency W and conventional X band electron paramagnetic resonance (EPR) spectroscopy. The numbers of spins in the studied samples were estimated. The core-shell model of the HPHT nanodiamonds was proposed to explain the observed dependence of the concentration of the N0 paramagnetic centers. Two other observed paramagnetic centers are attributed to the two types of str...

  12. Contrasting responses of bacterial and fungal communities to aggregate-size fractions and long-term fertilizations in soils of northeastern China.

    Science.gov (United States)

    Liao, Hao; Zhang, Yuchen; Zuo, Qinyan; Du, Binbin; Chen, Wenli; Wei, Dan; Huang, Qiaoyun

    2018-04-20

    Soils, with non-uniform distribution of nutrients across different aggregate-size fractions, provide spatially heterogeneous microhabitats for microorganisms. However, very limited information is available on microbial distributions and their response to fertilizations across aggregate-size fractions in agricultural soils. Here, we examined the structures of bacterial and fungal communities across different aggregate-size fractions (2000-250 μm, 250-53 μm and fractions (>53 μm), especially 250-53 μm aggregates, which contain more soil C and N, are associated with greater microbial biomass and higher fungi/bacteria ratio. We firstly reported the fungal community composition in different aggregate-size fractions by HTS technology and found more Ascomycota but less Zygomycota in larger fractions with higher C content across all fertilization regimes. Fertilization and aggregate-size fractions significantly affect the compositions of bacterial and fungal communities although their effects are different. The bacterial community is mainly driven by fertilization, especially chemical fertilizers, and is closely related to the shifts of soil P (phosphorus). The fungal community is preferentially impacted by different aggregate-size fractions and is more associated with the changes of soil C and N. The distinct responses of microbial communities suggest different mechanisms controlling the assembly of soil bacterial and fungal communities at aggregate scale. The investigations of both bacterial and fungal communities could provide a better understanding on nutrient cycling across aggregate-size fractions. Copyright © 2018. Published by Elsevier B.V.

  13. Particle size fractionation of high-amylose rice (Goami 2) flour as an oil barrier in a batter-coated fried system

    Science.gov (United States)

    The particle size effects of high-amylose rice (Goami 2) flour on quality attributes of frying batters were characterized in terms of physicochemical, rheological, and oil-resisting properties. High-amylose rice flours were fractionated into four fractions (70, 198, 256, and 415 µm) of which morpho...

  14. Decrease of concentration and colloidal fraction of organic carbon and trace elements in response to the anomalously hot summer 2010 in a humic boreal lake

    International Nuclear Information System (INIS)

    Shirokova, L.S.; Pokrovsky, O.S.; Moreva, O.Yu.; Chupakov, A.V.; Zabelina, S.A.; Klimov, S.I.; Shorina, N.V.; Vorobieva, T.Ya.

    2013-01-01

    The colloidal distribution and size fractionation of organic carbon (OC), major elements and trace elements (TE) were studied in a seasonally stratified, organic-rich boreal lake, Lake Svyatoe, located in the European subarctic zone (NW Russia, Arkhangelsk region). This study took place over the course of 4 years in both winter and summer periods using an in situ dialysis technique (1 kDa, 10 kDa and 50 kDa) and traditional frontal filtration and ultrafiltration (5, 0.22 and 0.025 μm). We observed a systematic difference in dissolved elements and colloidal fractions between summer and winter periods with the highest proportion of organic and organo-ferric colloids (1 kDa–0.22 μm) observed during winter periods. The anomalously hot summer of 2010 in European Russia produced surface water temperatures of approximately 30 °C, which were 10° above the usual summer temperatures and brought about crucial changes in element speciation and size fractionation. In August 2010, the concentration of dissolved organic carbon (DOC) decreased by more than 30% compared to normal period, while the relative proportion of organic colloids decreased from 70–80% to only 20–30% over the full depth of the water column. Similarly, the proportion of colloidal Fe decreased from 90–98% in most summers and winters to approximately 60–70% in August 2010. During this hot summer, measurable and significant (> 30% compared to other periods) decreases in the colloidal fractions of Ca, Mg, Sr, Ba, Al, Ti, Ni, As, V, Co, Y, all rare earth elements (REEs), Zr, Hf, Th and U were also observed. In addition, dissolved ( 100 for Co), the second and third factors could have brought about the decrease of allochthonous DOC concentration as well as the concentration and proportion of organic and organo-mineral colloidal forms of non-essential low-soluble trace elements present in the form of organic colloids (Al, Y, Ti, Zr, Hf, Th, Pb, all REEs). It can be hypothesized that climate warming in

  15. Concentration Measurements of Suspended Load using ADV with Influence of the Particle Size

    Science.gov (United States)

    Schwarzwälder, Kordula

    2017-04-01

    ADV backscatter data can be used under certain conditions to gain information about the concentrations of suspended loads. This was shown in many studies before (Fugate and Friedrichs 2002; Chanson et al 2008; Ha et al. 2009). This paper reports on a pre-study to investigate the influence of particle size on concentration measurements for suspended sediment load with ADV. The study was conducted in a flume in the Oskar-von-Miller-Institute using fresh water from a river including the natural suspended load. The ADV used in the experiments was a Vectrino Profiler (Nortek). In addition water samples were taken for TSS and TOC. For the measurements a surge was generated in the flume to ensure that also particles of larger size will be present in the water phase. The measurements and samples were taken during the whole surge event. Therefore we were able to find a good correlation between the backscatter data of the ADV and the TSS as well as TOC results. For the decreasing part of the flow event the concentration of TOC in the suspended load of the water phase is decreasing much slower than the TSS and results in a damped decrease of the backscatter values. This means that the results for concentration measurements might be slightly influenced by the size of the particles. Further evaluations of measurements conducted with a LISST SL (Sequoia) will be investigated to show the trend of the particle sizes during this process and fortify this result. David C. Fugate, Carl T. Friedrichs, Determining concentration and fall velocity of estuarine particle populations using ADV, OBS and LISST, Continental Shelf Research, Volume 22, Issues 11-13, 2002 H.K. Ha, W.-Y. Hsu, J.P.-Y. Maa, Y.Y. Shao, C.W. Holland, Using ADV backscatter strength for measuring suspended cohesive sediment concentration, Continental Shelf Research, Volume 29, Issue 10, 2009 Hubert Chanson, Maiko Takeuchi, Mark Trevethan, Using turbidity and acoustic backscatter intensity as surrogate measures of

  16. Contribution of particle-size-fractionated airborne lead to blood lead during the National Health and Nutrition Examination Survey, 1999-2008.

    Science.gov (United States)

    Meng, Qingyu; Richmond-Bryant, Jennifer; Davis, J Allen; Cohen, Jonathan; Svendsgaard, David; Brown, James S; Tuttle, Lauren; Hubbard, Heidi; Rice, Joann; Vinikoor-Imler, Lisa; Sacks, Jason D; Kirrane, Ellen; Kotchmar, Dennis; Hines, Erin; Ross, Mary

    2014-01-21

    The objective of this work is to examine associations between blood lead (PbB) and air lead (PbA) in particulate matter measured at different size cuts by use of PbB concentrations from the National Health and Nutrition Examination Survey and PbA concentrations from the U.S. Environmental Protection Agency for 1999-2008. Three size fractions of particle-bound PbA (TSP, PM10, and PM2.5) data with different averaging times (current and past 90-day average) were utilized. A multilevel linear mixed effect model was used to characterize the PbB-PbA relationship. At 0.15 μg/m(3), a unit decrease in PbA in PM10 was significantly associated with a decrease in PbB of 0.3-2.2 μg/dL across age groups and averaging times. For PbA in PM2.5 and TSP, slopes were generally positive but not significant. PbB levels were more sensitive to the change in PbA concentrations for children (1-5 and 6-11 years) and older adults (≥ 60 years) than teenagers (12-19 years) and adults (20-59 years). For the years following the phase-out of Pb in gasoline and a resulting upward shift in the PbA particle size distribution, PbA in PM10 was a statistically significant predictor of PbB. The results also suggest that age could affect the PbB-PbA association, with children having higher sensitivity than adults.

  17. Concentration of Proteins and Protein Fractions in Blood Plasma of Chickens Hatched from Eggs Irradiated with Low Level Gamma Rays

    International Nuclear Information System (INIS)

    Kraljevic, P.; Vilic, M.; Simpraga, M.; Matisic, D.; Miljanic, S.

    2011-01-01

    In literature there are many results which have shown that low dose radiation can stimulate many physiological processes of living organism. In our earlier paper it was shown that low dose of gamma radiation has a stimulative effect upon metabolic process in chickens hatched from eggs irradiated before incubation. This was proved by increase of body weight gain and body weight, as well as by increase of two enzymes activities in blood plasma (aspartate aminotransferase and alanine aminotransferase) which play an important role in protein metabolism. Therefore, an attempt was made to determine the effect of eggs irradiation by low dose gamma rays upon concentration of total proteins and protein fractions in the blood plasma of chickens hatched from irradiated eggs. The eggs of heavy breed chickens were irradiated with a dose of 0.15 Gy gamma radiation (60Co) before incubation. Along with the chickens which were hatched from irradiated eggs, there was a control group of chickens hatched from nonirradiated eggs. All other conditions were the same for both groups of chickens. Blood samples were taken from the right jugular vein on the 1 s t and 3 r d day, or from the wing vein on days 5 and 7 after hatching. The total proteins concentration in the blood plasma was determined by the biuret method using Boehringer Mannheim GmbH optimized kits. The protein fractions (albumin, α 1 -globulin, α 2 -globulin, β- and γ-globulins) were estimated electrophoretically on Cellogel strips. The total proteins concentration was significantly decreased in blood plasma of chickens hatched from irradiated eggs on days 3 (P t h day (P 2 -globulin was decreased on days 1 (P t h day of life. Obtained results indicate that low dose of gamma radiation has mostly inhibitory effect upon concentration of total proteins and protein fractions in the blood plasma of chickens hatched from irradiated eggs before incubation. (author)

  18. Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.

    Science.gov (United States)

    Cho, Jung Sang; Lee, Jeong-Cheol; Rhee, Sang-Hoon

    2016-02-01

    In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate. © 2015 Wiley Periodicals, Inc.

  19. Size-exclusion chromatography for the determination of the boiling point distribution of high-boiling petroleum fractions.

    Science.gov (United States)

    Boczkaj, Grzegorz; Przyjazny, Andrzej; Kamiński, Marian

    2015-03-01

    The paper describes a new procedure for the determination of boiling point distribution of high-boiling petroleum fractions using size-exclusion chromatography with refractive index detection. Thus far, the determination of boiling range distribution by chromatography has been accomplished using simulated distillation with gas chromatography with flame ionization detection. This study revealed that in spite of substantial differences in the separation mechanism and the detection mode, the size-exclusion chromatography technique yields similar results for the determination of boiling point distribution compared with simulated distillation and novel empty column gas chromatography. The developed procedure using size-exclusion chromatography has a substantial applicability, especially for the determination of exact final boiling point values for high-boiling mixtures, for which a standard high-temperature simulated distillation would have to be used. In this case, the precision of final boiling point determination is low due to the high final temperatures of the gas chromatograph oven and an insufficient thermal stability of both the gas chromatography stationary phase and the sample. Additionally, the use of high-performance liquid chromatography detectors more sensitive than refractive index detection allows a lower detection limit for high-molar-mass aromatic compounds, and thus increases the sensitivity of final boiling point determination. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Toxicologically important trace elements and organic compounds investigated in size-fractionated urban particulate matter collected near the Prague highway.

    Science.gov (United States)

    Sysalová, Jiřina; Sýkorová, Ivana; Havelcová, Martina; Száková, Jiřina; Trejtnarová, Hana; Kotlík, Bohumil

    2012-10-15

    Urban particulate matter was collected in the most exposed area of Prague, near a busy highway, in order to provide petrographic and chemical characterization useful for health impact assessment in that locality or other applications. Samples were collected from filters of the air conditioning system in two years, 2009 and 2010, and sieved into four grain-size fractions: 0.507-0.119 mm, 0.119-0.063 mm, origin and their morphology were studied by optical and electron microscopy. Organic solvent extracts of the samples were analyzed using gas chromatography to compare the organic compound distribution in fractions. Only slight differences between 2009 and 2010 years are visible. The relatively high extractable part of most investigated elements confirms mobility and potential availability to organisms. The changes can be recognized in the petrographic and organic composition in samples from both years, which were likely the result of various inputs of source materials. Specific organic marker compounds indicate contribution from fossil fuels, plant materials and bacteria. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Concentrations of polycyclic aromatic hydrocarbons in resuspendable fraction of settled bus dust and its implications for human exposure.

    Science.gov (United States)

    Gao, Peng; Liu, Sa; Feng, Yujie; Lin, Nan; Lu, Binyu; Zhang, Zhaohan; Cui, Fuyi; Xing, Baoshan; Hammond, S Katharine

    2015-03-01

    This preliminary study measured Polycyclic Aromatic Hydrocarbons (PAHs) concentrations in the resuspendable fraction of settled dust on 39 bus lines, to evaluate the impact of engine type (gasoline and compressed natural gas) on exposure for commuters and drivers. Benzo(b)fluoranthene(BbF) was the predominant PAH in resuspendable fraction of settled bus dust. The concentration of total PAHs was 92.90 ± 116.00 μg/g (range: 0.57-410) in gasoline buses and 3.97 ± 1.81 (range: 2.01-9.47) in compressed natural gas (CNG) buses. Based on Benzo[a]pyrene (BaP) equivalent concentrations for the sum of 16 PAHs, the average daily dose (ADD) via dust ingestion and dermal contact was calculated. The ADD of PAHs was higher for commuters and drivers in gasoline-powered buses than in buses using CNG buses. For both short and long duration journeys, young commuters were exposed to higher levels of PAHs via dust ingestion and dermal contact than adult commuters. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Concentration-dependent, size-independent toxicity of citrate capped AuNPs in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Giuseppe Vecchio

    Full Text Available The expected potential benefits promised by nanotechnology in various fields have led to a rapid increase of the presence of engineered nanomaterials in a high number of commercial goods. This is generating increasing questions about possible risks for human health and environment, due to the lack of an in-depth assessment of the physical/chemical factors responsible for their toxic effects. In this work, we evaluated the toxicity of monodisperse citrate-capped gold nanoparticles (AuNPs of different sizes (5, 15, 40, and 80 nm in the model organism Drosophila melanogaster, upon ingestion. To properly evaluate and distinguish the possible dose- and/or size-dependent toxicity of the AuNPs, we performed a thorough assessment of their biological effects, using two different dose-metrics. In the first approach, we kept constant the total surface area of the differently sized AuNPs (Total Exposed Surface area approach, TES, while, in the second approach, we used the same number concentration of the four different sizes of AuNPs (Total Number of Nanoparticles approach, TNN. We observed a significant AuNPs-induced toxicity in vivo, namely a strong reduction of Drosophila lifespan and fertility performance, presence of DNA fragmentation, as well as a significant modification in the expression levels of genes involved in stress responses, DNA damage recognition and apoptosis pathway. Interestingly, we found that, within the investigated experimental conditions, the toxic effects in the exposed organisms were directly related to the concentration of the AuNPs administered, irrespective of their size.

  3. Concentration, size distribution and dry deposition of amines in atmospheric particles of urban Guangzhou, China

    Science.gov (United States)

    Liu, Fengxian; Bi, Xinhui; Zhang, Guohua; Peng, Long; Lian, Xiufeng; Lu, Huiying; Fu, Yuzhen; Wang, Xinming; Peng, Ping'an; Sheng, Guoying

    2017-12-01

    Size-segregated PM10 samples were collected in Guangzhou, China during autumn of 2014. Nine amines, including seven aliphatic amines and two heterocyclic amines, were detected using a gas chromatography-mass spectrometer after derivatization by benzenesulfonyl chloride. The total concentration of the nine amines (Ʃamines) was 79.6-140.9 ng m-3 in PM10. The most abundant species was methylamine (MA), which had a concentration of 29.2-70.1 ng m-3. MA, dimethylamine (DMA), diethylamine (DEA) and dibutylamine (DBA) were the predominant amines in the samples and accounted for approximately 80% of Ʃamines in each size segment. Two heterocyclic amines, pyrrolidine (PYR) and morpholine (MOR), were detected in all samples and had average concentrations of 1.14 ± 0.37 and 1.89 ± 0.64 ng m-3, respectively, in particles with aerodynamic diameters ammonium ranged from 0.0068 to 0.0107 in particles with diameters <1.5 μm, and the maximum ratio occurred in the smallest particles (diameter< 0.49 μm). The average dry deposition flux and velocity of Ʃamines in PM10 were 7.9 ± 1.6 μg m-2 d-1 and 0.084 ± 0.0021 cm s-1, respectively. The results of this study provide essential information on the contribution of amines to secondary organic aerosols and dry removal mechanisms in urban areas.

  4. Influential parameters on particle concentration and size distribution in the mainstream of e-cigarettes

    International Nuclear Information System (INIS)

    Fuoco, F.C.; Buonanno, G.; Stabile, L.; Vigo, P.

    2014-01-01

    Electronic cigarette-generated mainstream aerosols were characterized in terms of particle number concentrations and size distributions through a Condensation Particle Counter and a Fast Mobility Particle Sizer spectrometer, respectively. A thermodilution system was also used to properly sample and dilute the mainstream aerosol. Different types of electronic cigarettes, liquid flavors, liquid nicotine contents, as well as different puffing times were tested. Conventional tobacco cigarettes were also investigated. The total particle number concentration peak (for 2-s puff), averaged across the different electronic cigarette types and liquids, was measured equal to 4.39 ± 0.42 × 10 9 part. cm −3 , then comparable to the conventional cigarette one (3.14 ± 0.61 × 10 9 part. cm −3 ). Puffing times and nicotine contents were found to influence the particle concentration, whereas no significant differences were recognized in terms of flavors and types of cigarettes used. Particle number distribution modes of the electronic cigarette-generated aerosol were in the 120–165 nm range, then similar to the conventional cigarette one. -- Highlights: • High particle number concentrations measured in e-cigarettes' mainstream aerosol. • Particle concentrations were higher than conventional tobacco cigarette ones. • Nicotine content and puffing times influenced particle concentrations. • Flavoring and type of cigarette did not affect the particle number concentration. • Particle number distribution mode of e-cigarette aerosol was equal to 120–165 nm. -- The mainstream aerosol generated by electronic cigarettes was characterized and the effect of each operating parameter was evaluated: results were similar to conventional cigarette ones

  5. Turbulent Concentration of mm-Size Particles in the Protoplanetary Nebula: Scale-Dependent Cascades

    Science.gov (United States)

    Cuzzi, J. N.; Hartlep, T.

    2015-01-01

    The initial accretion of primitive bodies (here, asteroids in particular) from freely-floating nebula particles remains problematic. Traditional growth-by-sticking models encounter a formidable "meter-size barrier" (or even a mm-to-cm-size barrier) in turbulent nebulae, making the preconditions for so-called "streaming instabilities" difficult to achieve even for so-called "lucky" particles. Even if growth by sticking could somehow breach the meter size barrier, turbulent nebulae present further obstacles through the 1-10km size range. On the other hand, nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids. Theoretical understanding of nebula turbulence is itself in flux; recent models of MRI (magnetically-driven) turbulence favor low-or- no-turbulence environments, but purely hydrodynamic turbulence is making a comeback, with two recently discovered mechanisms generating robust turbulence which do not rely on magnetic fields at all. An important clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids; scenarios leading directly from independent nebula particulates to large objects of this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios. The leapfrog scenario we have studied in detail involves formation of dense clumps of aerodynamically selected, typically mm-size particles in turbulence, which can under certain conditions shrink inexorably on 100-1000 orbit timescales and form 10-100km diameter sandpile planetesimals. There is evidence that at least the ordinary chondrite parent bodies were initially composed entirely of a homogeneous mix of such particles. Thus, while they are arcane, turbulent concentration models acting directly on chondrule size particles are worthy of deeper study. The typical sizes of planetesimals and the rate of their formation can be

  6. Effects of Crumb Rubber Size and Concentration on Performance of Porous Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Altan Cetin

    2013-01-01

    Full Text Available The purpose of this study is to investigate the effect of size distribution and concentration of crumb rubber on the performance characteristics of porous asphalt mixture. The recycling of scrap tires in asphalt pavements appears as an important alternative providing a large-scale market. The characteristics of bitumen are very important with regard to service life of porous asphalt pavement. The experimental study consists of two main steps. Firstly, the mixture design was performed to determine the optimum bitumen content. In the latter step, the mixtures were modified by dry process using crumb rubber in three different grain size distributions of #4~#20, #20~#200, and #4~#200 and rubber content of 10%, 15%, and 20% as weight of optimum bitumen. The permeability, Cantabro abrasion loss, indirect tensile strength, moisture susceptibility, and resilient modulus tests were carried out on the specimens. Test results show that #20~#200 sized rubber particles reduced air voids and coefficient of permeability, while they increased the Cantabro abrasion loss. In general, increasing the crumb rubber size and content decreased the performance characteristics of the porous asphalt mixtures.

  7. The effect of Fe, Mn, Ni and Pb Load on Soil and its enrichment factor ratios in different soil grain size fractions as an Indicator for soil pollution

    International Nuclear Information System (INIS)

    Rabie, F.H.; Abdel-Sabour, M.F.

    2000-01-01

    An industrial area north of greater Cairo was selected to investigate the impact of intensive industrial activities on soil characteristics and Fe, Mn, Ni and Pb total content. The studied area was divided to six sectors according to its source of irrigation water and/or probability of pollution. Sixteen soil profiles were dug and soil samples were taken, air dried, fractionated to different grain size fractions, then total heavy metals (Fe, Mn, Ni and Pb) were determined using ICP technique. The enrichment factor for each metal for each soil fraction/soil layer was estimated and discussed. The highest EF ratios in the clay fraction was mainly with Pb which indicated the industrial impact on the soil. In case of sand fraction, Mn was the highest always compared to other studied metals. Concerning silt fraction, a varied accumulation of Fe, Mn, and Pb was observed with soil depth and different soil profiles

  8. Structural composition of organic matter in particle-size fractions of soils along a climo-biosequence in the main range of Peninsular Malaysia

    Science.gov (United States)

    Jafarzadeh-Haghighi, Amir Hossein; Shamshuddin, Jusop; Hamdan, Jol; Zainuddin, Norhazlin

    2016-09-01

    Information on structural composition of organic matter (OM) in particle-size fractions of soils along a climo-biosequence is sparse. The objective of this study was to examine structural composition and morphological characteristics of OM in particle-size fractions of soils along a climo-biosequence in order to better understand the factors and processes affecting structural composition of soil organic matter. To explore changes in structural composition of OM in soils with different pedogenesis, the A-horizon was considered for further analyses including particle-size fractionation, solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM). Due to the increase in the thickness of organic layer with increasing elevation, the A-horizon was situated at greater depth in soils of higher elevation. The relationship between relative abundances of carbon (C) structures and particle-size fractions was examined using principal component analysis (PCA). It was found that alkyl C (20.1-73.4%) and O-alkyl C (16.8-67.7%) dominated particle-size fractions. The proportion of alkyl C increased with increasing elevation, while O-alkyl C showed an opposite trend. Results of PCA confirmed this finding and showed the relative enrichment of alkyl C in soils of higher elevation. Increase in the proportion of alkyl C in 250-2000 μm fraction is linked to selective preservation of aliphatic compounds derived from root litter. SEM results showed an increase in root contribution to the 250-2000 μm fraction with increasing elevation. For the changes in structural composition of OM in particle-size fractions of soils along the studied climo-biosequence are attributed to site-specific differences in pedogenesis as a function of climate and vegetation.

  9. Dynamics of suspended sediment concentration, flow discharge and sediment particle size interdependency to identify sediment source

    Science.gov (United States)

    Sadeghi, Seyed Hamidreza; Singh, Vijay P.

    2017-11-01

    Spatiotemporal behavior of sediment yield is a key for proper watershed management. This study analyzed statistical characteristics and trends of suspended sediment concentration (SCS), flow discharge (FD) and sediment particle sizes using data from 24 gage stations scattered throughout the United States. Analysis showed significant time- and location-specific differences of these variables. The median values of SSC, FD and percentage of particle sizes smaller than 63 μm (P63) for all 24 gage stations were found to be 510.236 mg l-1 (right skewed), 45.406 m3 s-1 (left skewed) and 78.648% (right skewed), respectively. Most of the stations exhibited significant trends (P practices which may call for local or regional planning based on natural (i.e., precipitation amount, type and erosivity, watershed area, and soil erodibility) and human-affected (i.e., land use and hydraulic structures and water resources management) factors governing the study variables.

  10. How comparable are size-resolved particle number concentrations from different instruments?

    Science.gov (United States)

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

    2012-12-01

    The need for comparability of particle size resolved measurements originates from multiple drivers including: (i) Recent suggestions that air quality standards for particulate matter should migrate from being mass-based to incorporating number concentrations. This move would necessarily be predicated on measurement comparability which is absolutely critical to compliance determination. (ii) The need to quantify and diagnose causes of variability in nucleation and growth rates in nano-particle experiments conducted in different locations. (iii) Epidemiological research designed to identify key parameters in human health responses to fine particle exposure. Here we present results from a detailed controlled laboratory instrument inter-comparison experiment designed to investigate data comparability in the size range of 2.01-523.3 nm across a range of particle composition, modal diameter and absolute concentration. Particle size distributions were generated using a TSI model 3940 Aerosol Generation System (AGS) diluted using zero air, and sampled using four TSI Scanning Mobility Particle Spectrometer (SMPS) configurations and a TSI model 3091 Fast Mobility Particle Sizer (FMPS). The SMPS configurations used two Electrostatic Classifiers (EC) (model 3080) attached to either a Long DMA (LDMA) (model 3081) or a Nano DMA (NDMA) (model 3085) plumbed to either a TSI model 3025A Butanol Condensed Particle Counting (CPC) or a TSI model 3788 Water CPC. All four systems were run using both high and low flow conditions, and were operated with both the internal diffusion loss and multiple charge corrections turned on. The particle compositions tested were sodium chloride, ammonium nitrate and olive oil diluted in ethanol. Particles of all three were generated at three peak concentration levels (spanning the range observed at our experimental site), and three modal particle diameters. Experimental conditions were maintained for a period of 20 minutes to ensure experimental

  11. Size-dependent concentration of N0 paramagnetic centres in HPHT nanodiamonds

    Directory of Open Access Journals (Sweden)

    B.V. Yavkin, G.V. Mamin, M.R. Gafurov, S.B. Orlinskii

    2015-12-01

    Full Text Available Size-calibrated commercial nanodiamonds synthesized by high-pressure high-temperature (HPHT technique were studied by high-frequency W- and conventional X-band electron paramagnetic resonance (EPR spectroscopy. The numbers of spins in the studied samples were estimated. The core-shell model of the HPHT nanodiamonds was proposed to explain the observed dependence of the concentration of the N0 paramagnetic centers. Two other observed paramagnetic centers are attributed to the two types of structures in the nanodiamond shell.

  12. Optical properties of size fractions of suspended particulate matter in littoral waters of Québec

    Science.gov (United States)

    Mohammadpour, Gholamreza; Gagné, Jean-Pierre; Larouche, Pierre; Montes-Hugo, Martin A.

    2017-11-01

    Mass-specific absorption (ai∗(λ)) and scattering (bi∗(λ)) coefficients were derived for four size fractions (i = 0.2-0.4, 0.4-0.7, 0.7-10, and > 10 µm, λ = wavelength in nm) of suspended particulate matter (SPM) and with samples obtained from surface waters (i.e., 0-2 m depth) of the Saint Lawrence Estuary and Saguenay Fjord (SLE-SF) during June of 2013. For the visible-near-infrared spectral range (i.e., λ = 400-710 nm), mass-specific absorption coefficients of total SPM (i.e., particulates > 0.2 µm) (hereafter aSPM∗) had low values (e.g., 0.05 m2 g-1 at λ = 440 nm) corresponded with locations of the upper estuary and SF where particulates were mineral-rich and/or their mean diameter was relatively small. The variability of two optical proxies (the spectral slope of particulate beam attenuation coefficient and the mass-specific particulate absorption coefficient, hereafter γ and Svis, respectively) with respect to changes in particle size distribution (PSD) and chemical composition was also examined. The slope of the PSD was correlated with bi∗(550) (Spearman rank correlation coefficient ρs up to 0.37) and ai∗(440) estimates (ρs up to 0.32) in a comparable way. Conversely, the contribution of particulate inorganic matter to total mass of SPM (FSPMPIM) had a stronger correlation with ai∗ coefficients at a wavelength of 440 nm (ρs up to 0.50). The magnitude of γ was positively related to FSPMi or the contribution of size fraction i to the total mass of SPM (ρs up to 0.53 for i = 0.2-0.4 µm). Also, the relation between γ and FSPMPIM variability was secondary (ρs = -0.34, P > 0.05). Lastly, the magnitude of Svis was inversely correlated with aSPM∗(440) (ρs = -0.55, P = 0.04) and FSPMPIM (ρs = -0.62, P = 0.018) in sampling locations with a larger marine influence (i.e., lower estuary).

  13. Variability of left ventricular ejection fraction and volumes with quantitative gated SPECT: influence of algorithm, pixel size and reconstruction parameters in small and normal-sized hearts

    International Nuclear Information System (INIS)

    Hambye, Anne-Sophie; Vervaet, Ann; Dobbeleir, Andre

    2004-01-01

    Several software packages are commercially available for quantification of left ventricular ejection fraction (LVEF) and volumes from myocardial gated single-photon emission computed tomography (SPECT), all of which display a high reproducibility. However, their accuracy has been questioned in patients with a small heart. This study aimed to evaluate the performances of different software and the influence of modifications in acquisition or reconstruction parameters on LVEF and volume measurements, depending on the heart size. In 31 patients referred for gated SPECT, 64 2 and 128 2 matrix acquisitions were consecutively obtained. After reconstruction by filtered back-projection (Butterworth, 0.4, 0.5 or 0.6 cycles/cm cut-off, order 6), LVEF and volumes were computed with different software [three versions of Quantitative Gated SPECT (QGS), the Emory Cardiac Toolbox (ECT) and the Stanford University (SU-Segami) Medical School algorithm] and processing workstations. Depending upon their end-systolic volume (ESV), patients were classified into two groups: group I (ESV>30 ml, n=14) and group II (ESV 2 to 128 2 were associated with significantly larger volumes as well as lower LVEF values. Increasing the filter cut-off frequency had the same effect. With SU-Segami, a larger matrix was associated with larger end-diastolic volumes and smaller ESVs, resulting in a highly significant increase in LVEF. Increasing the filter sharpness, on the other hand, had no influence on LVEF though the measured volumes were significantly larger. (orig.)

  14. THE EFFECT OF SOIL CONDITIONERS ON CELLULOSE, HEMICELLULOSE, AND THE ADL FIBRE FRACTION CONCENTRATION IN DACTYLIS GLOMERATA AND LOLIUM PERENNE

    Directory of Open Access Journals (Sweden)

    Milena Truba

    2017-01-01

    Full Text Available Replicated three times, the research was conducted in the experimental field between 2011 and 2014. Three soil conditioners with the following trade names: UGmax, Eko-Użyźniacz, and Humus Active Papka were used in the experiment, separately or together with NPK fertilisers. They were all used on plots sown with two species of grass, Dactylis glomerata of the Bora variety and Lolium perenne of the Info variety. The plant material from both grass species was tested for the concentration of ADL fraction (% DM, cellulose (% DM, and hemicellulose (% DM. It was found that the concentration of cellulose, hemicelluloses, and the ADL fraction was significantly higher in the biomass of Dactylis glomerata than in the biomass of Lolium perenne. The grass from the plot with the UGmax soil conditioner applied had the highest amount of cellulose and hemicellulose. The lowest amount of those organic compounds was found in the grass treated with UGmax together with mineral fertilisers and in plants treated with Humus Active, together with mineral fertilisers. However, the fertilisers and conditioners did not increase the ADL content in both grass species.

  15. Vertical profiles of black carbon concentration and particle number size distribution in the North China Plain

    Science.gov (United States)

    Ran, L.; Deng, Z.

    2013-12-01

    The vertical distribution of aerosols is of great importance to our understanding in the impacts of aerosols on radiation balance and climate, as well as air quality and public health. To better understand and estimate the effects of atmospheric components including trace gases and aerosols on atmospheric environment and climate, an intensive field campaign, Vertical Observations of trace Gases and Aerosols in the North China Plain (VOGA-NCP), was carried out from late July to early August 2013 over a rural site in the polluted NCP. During the campaign, vertical profiles of black carbon (BC) concentration and particle number size distribution were measured respectively by a micro-Aethalometer and an optical particle counter attached to a tethered balloon within 1000 m height. Meteorological parameters, including temperature, relative humidity, wind speed and wind direction, were measured simultaneously by a radiosonde also attached to the tethered balloon. Preliminary results showed distinct diurnal variations of the vertical distribution of aerosol total number concentration and BC concentration, following the development of the mixing layer. Generally, there was a well mixing of aerosols within the mixing layer and a sharp decrease above the mixing layer. Particularly, a small peak of BC concentrations was observed around 400-500 m height for several profiles. Further analysis would be needed to explain such phenomenon. It was also found that measured vertical profiles of BC using the filter-based method might be affected by the vertical distribution of relative humidity.

  16. Real-time measurements of suspended sediment concentration and particle size using five techniques

    Science.gov (United States)

    Felix, D.; Albayrak, I.; Abgottspon, A.; Boes, R. M.

    2016-11-01

    Fine sediments are important in the design and operation of hydropower plants (HPPs), in particular with respect to sediment management and hydro-abrasive erosion in hydraulic machines. Therefore, there is a need for reliable real-time measurements of suspended sediment mass concentration (SSC) and particle size distribution (PSD). The following instruments for SSC measurements were investigated in a field study during several years at the HPP Fieschertal in the Swiss Alps: (1) turbidimeters, (2) a Laser In-Situ Scattering and Trans- missometry instrument (LISST), (3) a Coriolis Flow and Density Meter (CFDM), (4) acoustic transducers, and (5) pressure sensors. LISST provided PSDs in addition to concentrations. Reference SSCs were obtained by gravimetrical analysis of automatically taken water samples. In contrast to widely used turbidimeters and the single-frequency acoustic method, SSCs obtained from LISST, the CFDM or the pressure sensors were less or not affected by particle size variations. The CFDM and the pressure sensors allowed measuring higher SSC than the optical or the acoustic techniques (without dilution). The CFDM and the pressure sensors were found to be suitable to measure SSC ≥ 2 g/l. In this paper, the measuring techniques, instruments, setup, methods for data treatment, and selected results are presented and discussed.

  17. Fractal aspects of the flow and shear behaviour of free-flowable particle size fractions of pharmaceutical directly compressible excipient sorbitol.

    Science.gov (United States)

    Hurychová, Hana; Lebedová, Václava; Šklubalová, Zdenka; Dzámová, Pavlína; Svěrák, Tomáš; Stoniš, Jan

    Flowability of powder excipients is directly influenced by their size and shape although the granulometric influence of the flow and shear behaviour of particulate matter is not studied frequently. In this work, the influence of particle size on the mass flow rate through the orifice of a conical hopper, and the cohesion and flow function was studied for four free-flowable size fractions of sorbitol for direct compression in the range of 0.080-0.400 mm. The particles were granulometricaly characterized using an optical microscopy; a boundary fractal dimension of 1.066 was estimated for regular sorbitol particles. In the particle size range studied, a non-linear relationship between the mean particle size and the mass flow rate Q10 (g/s) was detected having amaximum at the 0.245mm fraction. The best flow properties of this fraction were verified with aJenike shear tester due to the highest value of flow function and the lowest value of the cohesion. The results of this work show the importance of the right choice of the excipient particle size to achieve the best flow behaviour of particulate material.Key words: flowability size fraction sorbitol for direct compaction Jenike shear tester fractal dimension.

  18. Tangential flow ultrafiltration: a "green" method for the size selection and concentration of colloidal silver nanoparticles.

    Science.gov (United States)

    Anders, Catherine B; Baker, Joshua D; Stahler, Adam C; Williams, Austin J; Sisco, Jackie N; Trefry, John C; Wooley, Dawn P; Pavel Sizemore, Ioana E

    2012-10-04

    Nowadays, AgNPs are extensively used in the manufacture of consumer products,(1) water disinfectants,(2) therapeutics,(1, 3) and biomedical devices(4) due to their powerful antimicrobial properties.(3-6) These nanoparticle applications are strongly influenced by the AgNP size and aggregation state. Many challenges exist in the controlled fabrication(7) and size-based isolation(4,8) of unfunctionalized, homogenous AgNPs that are free from chemically aggressive capping/stabilizing agents or organic solvents.(7-13) Limitations emerge from the toxicity of reagents, high costs or reduced efficiency of the AgNP synthesis or isolation methods (e.g., centrifugation, size-dependent solubility, size-exclusion chromatography, etc.).(10,14-18) To overcome this, we recently showed that TFU permits greater control over the size, concentration and aggregation state of Creighton AgNPs (300 ml of 15.3 μg ml(-1) down to 10 ml of 198.7 μg ml(-1)) than conventional methods of isolation such as ultracentrifugation.(19) TFU is a recirculation method commonly used for the weight-based isolation of proteins, viruses and cells.(20,21) Briefly, the liquid sample is passed through a series of hollow fiber membranes with pore size ranging from 1,000 kD to 10 kD. Smaller suspended or dissolved constituents in the sample will pass through the porous barrier together with the solvent (filtrate), while the larger constituents are retained (retentate). TFU may be considered a "green" method as it neither damages the sample nor requires additional solvent to eliminate toxic excess reagents and byproducts. Furthermore, TFU may be applied to a large variety of nanoparticles as both hydrophobic and hydrophilic filters are available. The two main objectives of this study were: 1) to illustrate the experimental aspects of the TFU approach through an invited video experience and 2) to demonstrate the feasibility of the TFU method for larger volumes of colloidal nanoparticles and smaller volumes of

  19. Emulsion Polymerization of Etyl Acrylate: The Effect of Surfactant, Initiator Concentration and PolymerizationTechnique on Particle Size Distribution

    OpenAIRE

    Nitri Arinda; Emil Budianto; Helmiyati

    2009-01-01

    Emulsion polymerization was conducted using ethyl acrylate monomer. Theeffect of sodium lauryl sulfate concentration, ammonium persulfate concentration, the various of polymerizationtechniques and feeding time to the conversion, particle size and its distribution were observed. The purpose of thisresearch is to obtain the optimum condition of ethyl acrylate homopolymer with particle size around 100 nm, to get theparticle size distribution monodisperse and to get solid content value of the exp...

  20. Attached, unattached fraction of progeny concentrations and equilibrium factor for dose assessments from {sup 222}Rn and {sup 220}Rn

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Parminder; Saini, Komal; Bajwa, Bikramjit Singh [Guru Nanak Dev University, Department of Physics, Amritsar, Punjab (India); Mishra, Rosaline; Sahoo, Bijay Kumar [Bhabha Atomic Research Centre, Radiological Physics and Advisory Division, Mumbai (India)

    2016-08-15

    In this study, measurements of indoor radon ({sup 222}Rn), thoron ({sup 220}Rn) and their equilibrium equivalent concentration (EEC) were carried out in 96 dwellings from 22 different villages situated in Hamirpur district, Himachal Pradesh, India, by using LR-115 type II-based pinhole twin cup dosimeters and deposition-based progeny sensors (DRPS/DTPS). The annual average indoor {sup 222}Rn and {sup 220}Rn concentrations observed in these dwellings were 63.82 and 89.59 Bq/m{sup 3}, respectively, while the average EEC (attached + unattached) for {sup 222}Rn and {sup 220}Rn was 29.28 and 2.74 Bq/m{sup 3}. For {sup 222}Rn (f{sub Rn}) and {sup 220}Rn (f{sub Tn}), the average values of unattached fraction were 0.11 and 0.09, respectively. The equilibrium factors for radon (F{sub Rn}) and thoron (F{sub Tn}) varied from 0.12 to 0.77 with an average of 0.50, and from 0.01 to 0.34 with an average of 0.05, respectively. The annual inhalation dose due to mouth and nasal breathing was calculated using dose conversion factors and unattached fractions. The indoor annual effective doses for {sup 222}Rn (AEDR) and {sup 220}Rn (AEDT) were found to be 1.92 and 0.83 mSv a{sup -1}, respectively. The values of {sup 222}Rn/{sup 220}Rn concentrations and annual effective doses obtained in the present study are within the safe limits as recommended by the International Commission on Radiological Protection for indoor dwelling exposure conditions. (orig.)

  1. Concentration of "1"3"4Cs + "1"3"7Cs bonded to the organic fraction of sediments offshore Fukushima, Japan

    International Nuclear Information System (INIS)

    Ono, Tsuneo; Ambe, Daisuke; Kaeriyama, Hideki

    2015-01-01

    We conducted a sequential chemical extraction experiment for radiocesium ("1"3"4Cs + "1"3"7Cs) using 21 surface sediment samples and two sets of size-fractionated surface sediment samples collected offshore Fukushima. Our results support earlier reports in this area that organic substances in marine sediments have an apparently higher preference for radiocesium than mineral substances. Observations suggest that mineral and organic substances in the marine sediments offshore Fukushima have the same order of preference for radiocesium, primarily because of the existence of ionic competitors in seawater. The apparent preference of radiocesium for organic material is greater because of the partial coverage of sediment mineral surfaces by organic substances. By using these relationships, we created a 2-D map of radiocesium concentration in sediment organic fraction in offshore-Fukushima region. Combining our results with existing monitoring data of marine benthos in offshore-Fukushima sediments, we estimated a transfer coefficient of radiocesium from sediment organic materials to benthic polychaetes as less than 0.03-0.008. (author)

  2. Comparison of different filtration techniques for the pre-concentration of natural colloidal dispersions for field-flow-fractionation (FFF); Vergleich verschiedener Filtrationstechniken zur Aufkonzentrierung natuerlicher kolloidaler Dispersionen fuer die Feld-Fluss-Fraktionierung (FFF)

    Energy Technology Data Exchange (ETDEWEB)

    Saal, C.; Kammer, F. v.d. [Technische Univ. Hamburg-Harburg, Arbeitsbereich Umweltschutztechnik, Hamburg (Germany)

    2002-07-01

    The objektive of this study was to compare different pre-treatment techniques (active and passive filtration techniques applying various membranes) for field-flow-fractionation (FFF) analysis of natural aquatic colloids. In most cases FFF of natural water samples requires a pre-concentration step prior to analysis. The used FFF-method with online multi-detector-analysis (MDA) is a versatile method to specify the size distribution of particles (> 10 nm) in aqueous systems. Coupling FFF with trace element analysis (e. g. ICP-MS or total reflextion X-ray fluorescence (TXRF)) is a possibility for the determination of element/ size distributions. Analysing natural water samples with FFF a sample pre-treatment is needed in most cases, which can be a coarse filtration (> 5 {mu}m) to separate algea from the sample and a preconcentration of the colloidal fraction. The pre-treatment of the sample has to assure a minimum loss of colloidal particulate matter (CPM) and no change of size distribution. The different pre-concentration techniques were tested with water extractable soil colloids. We have developed methods with concentration factors F < 50 showing minor effects on the colloidal composition of the sample, so that these methods can be used to concentrate CPM of natural waters for size- and trace metal analysis. (orig.)

  3. Optical properties of size fractions of suspended particulate matter in littoral waters of Québec

    Directory of Open Access Journals (Sweden)

    G. Mohammadpour

    2017-11-01

    Full Text Available Mass-specific absorption (ai∗(λ and scattering (bi∗(λ coefficients were derived for four size fractions (i =  0.2–0.4, 0.4–0.7, 0.7–10, and > 10 µm, λ = wavelength in nm of suspended particulate matter (SPM and with samples obtained from surface waters (i.e., 0–2 m depth of the Saint Lawrence Estuary and Saguenay Fjord (SLE-SF during June of 2013. For the visible–near-infrared spectral range (i.e., λ = 400–710 nm, mass-specific absorption coefficients of total SPM (i.e., particulates > 0.2 µm (hereafter aSPM∗ had low values (e.g., < 0.01 m2 g−1 at λ = 440 nm in areas of the lower estuary dominated by particle assemblages with relatively large mean grain size and high particulate organic carbon and chlorophyll a per unit of mass of SPM. Conversely, largest aSPM∗ values (i.e., > 0.05 m2 g−1 at λ = 440 nm corresponded with locations of the upper estuary and SF where particulates were mineral-rich and/or their mean diameter was relatively small. The variability of two optical proxies (the spectral slope of particulate beam attenuation coefficient and the mass-specific particulate absorption coefficient, hereafter γ and Svis, respectively with respect to changes in particle size distribution (PSD and chemical composition was also examined. The slope of the PSD was correlated with bi∗(550 (Spearman rank correlation coefficient ρs up to 0.37 and ai∗(440 estimates (ρs up to 0.32 in a comparable way. Conversely, the contribution of particulate inorganic matter to total mass of SPM (FSPMPIM had a stronger correlation with ai∗ coefficients at a wavelength of 440 nm (ρs up to 0.50. The magnitude of γ was positively related to FSPMi or the contribution of size fraction i to the total mass of SPM (ρs up to 0.53 for i = 0.2–0.4 µm. Also, the relation between γ and FSPMPIM variability was secondary (ρs = −0.34, P > 0.05. Lastly, the magnitude

  4. Size-fractionation of groundwater arsenic in alluvial aquifers of West Bengal, India: the role of organic and inorganic colloids.

    Science.gov (United States)

    Majumder, Santanu; Nath, Bibhash; Sarkar, Simita; Chatterjee, Debashis; Roman-Ross, Gabriela; Hidalgo, Manuela

    2014-01-15

    Dissolved organic carbon (DOC) and Fe mineral phases are known to influence the mobility of arsenic (As) in groundwater. Arsenic can be associated with colloidal particles containing organic matter and Fe. Currently, no data is available on the dissolved phase/colloidal association of As in groundwater of alluvial aquifers in West Bengal, India. This study investigated the fractional distribution of As (and other metals/metalloids) among the particulate, colloidal and dissolved phases in groundwater to decipher controlling behavior of organic and inorganic colloids on As mobility. The result shows that 83-94% of As remained in the 'truly dissolved' phases (i.e., 0.05 μm size) colloidal particles, which indicates the close association of As with larger Fe-rich inorganic colloids. In smaller (i.e., <0.05 μm size) colloidal particles strong positive correlation is observed between As and DOC (r(2)=0.85), which highlights the close association of As with smaller organic colloids. As(III) is mainly associated with larger inorganic colloids, whereas, As(V) is associated with smaller organic/organometallic colloids. Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy confirm the association of As with DOC and Fe mineral phases suggesting the formation of dissolved organo-Fe complexes and colloidal organo-Fe oxide phases. Attenuated total reflectance-Fourier transform infrared spectroscopy further confirms the formation of As-Fe-NOM organometallic colloids, however, a detailed study of these types of colloids in natural waters is necessary to underpin their controlling behavior. © 2013 Elsevier B.V. All rights reserved.

  5. Soil Carbon Stock and Particle Size Fractions in the Central Amazon Predicted from Remotely Sensed Relief, Multispectral and Radar Data

    Directory of Open Access Journals (Sweden)

    Marcos B. Ceddia

    2017-02-01

    Full Text Available Soils from the remote areas of the Amazon Rainforest in Brazil are poorly mapped due to the presence of dense forest and lack of access routes. The use of covariates derived from multispectral and radar remote sensors allows mapping large areas and has the potential to improve the accuracy of soil attribute maps. The objectives of this study were to: (a evaluate the addition of relief, and vegetation covariates derived from multispectral images with distinct spatial and spectral resolutions (Landsat 8 and RapidEye and L-band radar (ALOS PALSAR for the prediction of soil organic carbon stock (CS and particle size fractions; and (b evaluate the performance of four geostatistical methods to map these soil properties. Overall, the results show that, even under forest coverage, the Normalized Difference Vegetation Index (NDVI and ALOS PALSAR backscattering coefficient improved the accuracy of CS and subsurface clay content predictions. The NDVI derived from RapidEye sensor improved the prediction of CS using isotopic cokriging, while the NDVI derived from Landsat 8 and backscattering coefficient were selected to predict clay content at the subsurface using regression kriging (RK. The relative improvement of applying cokriging and RK over ordinary kriging were lower than 10%, indicating that further analyses are necessary to connect soil proxies (vegetation and relief types with soil attributes.

  6. Differential pulmonary inflammation and in vitro cytotoxicity of size-fractionated fly ash particles from pulverized coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    M. Ian Gilmour; Silvia O' Connor; Colin A.J. Dick; C. Andrew Miller; William P. Linak [U.S. Environmental Protection Agency, Research Triangle Park, NC (United States). National Health and Environmental Effects Research Laboratory

    2004-03-01

    Exposure to airborne particulate matter (PM) has been associated with adverse health effects in humans. Pulmonary inflammatory responses were examined in CD1 mice after intratracheal instillation of 25 or 100 {mu}g of ultrafine ({lt}0.2 {mu}m), fine ({lt}2.5 {mu}m), and coarse ({gt}2.5 {mu}m) coal fly ash from a combusted Montana subbituminous coal, and of fine and coarse fractions from a combusted western Kentucky bituminous coal. After 18 hr, the lungs were lavaged and the bronchoalveolar fluid was assessed for cellular influx, biochemical markers, and pro-inflammatory cytokines. The responses were compared with saline and endotoxin as negative and positive controls, respectively. On an equal mass basis, the ultrafine particles from combusted Montana coal induced a higher degree of neutrophil inflammation and cytokine levels than did the fine or coarse PM. The western Kentucky fine PM caused a moderate degree of inflammation and protein levels in bronchoalveolar fluid that were higher than the Montana fine PM. Coarse PM did not produce any significant effects. In vitro experiments with rat alveolar macrophages showed that of the particles tested, only the Montana ultrafine displayed significant cytotoxicity. It is concluded that fly ash toxicity is inversely related with particle size and is associated with increased sulfur and trace element content. 42 refs., 5 figs., 3 tabs.

  7. Investigating high zircon concentrations in the fine fraction of stream sediments draining the Pan-African Dahomeyan Terrane in Nigeria

    International Nuclear Information System (INIS)

    Key, Roger M.; Johnson, Christopher C.; Horstwood, Matthew S.A.; Lapworth, Dan J.; Knights, Katherine V.; Kemp, Simon J.; Watts, Michael; Gillespie, Martin; Adekanmi, Michael; Arisekola, Tunde

    2012-01-01

    Sixteen hundred stream sediments (<150 μm fraction) collected during regional geochemical surveys in central and SW Nigeria have high median and maximum concentrations of Zr that exceed corresponding Zr concentrations found in stream sediments collected from elsewhere in the World with similar bedrock geology. X-ray diffraction studies on a sub-set of the analysed stream sediments showed that Zr is predominantly found in detrital zircon grains. However, the main proximal source rocks (Pan-African ‘Older Granites’ of Nigeria and their Proterozoic migmatitic gneiss country rocks) are not enriched in zircon (or Zr). Nevertheless, U–Pb LA-ICP-MS dating with cathodoluminescence imaging on detrital zircons, both from stream sediment samples and underlying Pan-African ‘Older Granites’ confirms a local bedrock source for the stream sediment zircons. A combination of tropical/chemical weathering and continuous physical weathering, both by ‘wet season’ flash flooding and ‘dry season’ unidirectional winds are interpreted to have effectively broken down bedrock silicate minerals and removed much of the resultant clay phases, thereby increasing the Zr contents in stream sediments. The strong correlation between winnowing index (Th/Al) and Zr concentration across the study area support this interpretation. Therefore, ‘anomalous’ high values of Zr, as well as other elements concentrated in resistant ‘heavy’ minerals in Nigeria’s streams may not reflect proximal bedrock concentrations of these elements. This conclusion has important implications for using stream sediment chemistry as an exploration tool in Nigeria for primary metal deposits associated with heavy minerals.

  8. Optical noninvasive calculation of hemoglobin components concentrations and fractional oxygen saturation using a ring-scattering pulse oximeter

    Science.gov (United States)

    Abdallah, Omar; Stork, Wilhelm; Muller-Glaser, Klaus

    2004-06-01

    The deficiencies of the currently used pulse oximeter are discussed in diverse literature. A hazardous pitfalls of this method is that the pulse oximeter will not detect carboxyhemoglobin (COHb) and methemoglobin (metHb) concentrations. This leads to incorrect measurement of oxygen saturation by carbon monoxide poisoning and methemoglobinemia. Also the total hemoglobin concentration will not be considered and can only be measured in-vitro up to now. A second pitfall of the standard pulse oximetry is that it will not be able to show a result by low perfusion of tissues. This case is available inter alia when the patient is under shock or has a low blood pressure. The new non-invasive system we designed measures the actual (fractional) oxygen saturation and hemoglobin concentration. It will enable us also to measure COHb and metHb. The measurement can be applied at better perfused body central parts. Four or more light emitting diodes (LEDs) or laser diodes (LDs) and five photodiodes (PDs) are used. The reflected light signal detected by photodiodes is processed using a modified Lambert-Beer law (I=I0×e-α.d ). According to this law, when a non scattering probe is irradiated with light having the incident intensity I0, the intensity of transmitted light I decays exponentially with the absorption coefficient a of that probe and its thickness d. Modifications of this law have been performed following the theoretical developed models in literature, Monte Carlo simulation and experimental measurement.

  9. H-binding of size- and polarity-fractionated soil and lignite humic acids after removal of metal and ash components

    Science.gov (United States)

    Drosos, Marios; Leenheer, Jerry A.; Avgeropoulos, Apostolos; Deligiannakis, Yiannis

    2014-01-01

    A fractionation technique, combining dialysis removal of metal and ash components with hydrofluoric acid and pH 10 citrate buffer followed by chromatography of dialysis permeate on XAD-8 resin at decreasing pH values, has been applied to lignite humic acid (lignite-HA) and soil humic acid (soil-HA). H-binding data and non ideal competitive adsorption-Donnan model parameters were obtained for the HA fractions by theoretical analysis of H-binding data which reveal a significant increase of the carboxyl and the phenolic charge for the lignite-HA fractions vs. the parental lignite humic acid (LParentalHA). The fractionated lignite-HA material consisted mainly of permeate fractions, some of which were fulvic acid-like. The fractionated soil-HA material consisted mainly of large macromolecular structures that did not permeate the dialysis membrane during deashing. Chargeable groups had comparable concentrations in soil-HA fractions and parental soil humic acid (SParentalHA), indicating minimal interference of ash components with carboxyl and phenolic (and/or enolic) groups. Fractionation of HA, combined with theoretical analysis of H-binding, can distinguish the supramolecular vs. macromolecular nature of fractions within the same parental HA.

  10. The Effect of Rice Fermented (Tape Ketan Hitam Liquid Fraction Concentrations and Incubation Times on pH, Viscosity and Organoleptic Quality of Goat Milk

    Directory of Open Access Journals (Sweden)

    Naili Iqrimah

    2013-09-01

    Full Text Available This study aimed to determine of interaction and the best of percentage rice fermented liquid fraction addition and incubation times on pH, viscosity and organoleptic quality. The experimental method was designed by factorial Completely Randomized Design (CRD which three times replicated. The treatment consists of rice fermented liquid fraction concentrations by 5 %, 15 %, 25 % and 35 % (v/v  and incubation times by 0 (without incubation , 8,16 and 24 hours. The results showed that the different concentration of rice fermented liquid fraction showed a significantly different effect on pH, viscosity, colour, smell, taste and textur, while  in incubation times gave a significantly different effect on pH, viscosity, smell, taste and textur but not give a significant effect on colour. The best combination obtained from addition of rice fermented liquid fraction 25 % and 24 hours of incubation times. Key words: goat milk, rice fermented liquid fraction, incubation times

  11. Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley

    Science.gov (United States)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-06-01

    The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 1.5 fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest particles and the relative distribution of the functional groups as compared to those previously observed for marine, biomass burning and secondary organic aerosol. The latter also allowed for the differentiation of urban combustion-related aerosol and biological particles. The five types of organic hydrogen accounted for the majority of WSOC for particles with dp > 3.0 μm and dp < 0.96 μm.

  12. Functional characterization of the water-soluble organic carbon of size fractionated aerosol in the Southern Mississippi Valley

    Science.gov (United States)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-02-01

    The chemical content of the water soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to: (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for the period when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp magnetic resonance. The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 0.96 fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosol and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest particles and the relative distribution of the functional groups as compared to those previously observed for marine, biomass burning and secondary organic aerosol. The latter also allowed for the differentiation of urban combustion-related aerosol and biological particles. The five types of organic hydrogen accounted for the majority of WSOC for particles with dp > 3.0 μm and dp < 0.96 μm.

  13. Speciation of organic matter in sandy soil size fractions as revealed by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy

    Science.gov (United States)

    Jiménez-Morillo, Nicasio T.; González-Vila, Francisco J.; Jordán, Antonio; Zavala, Lorena M.; de la Rosa, José M.; González-Pérez, José A.

    2015-04-01

    This research deals with the assessment of organic matter structural differences in soil physical fractions before and after lipid extractions. Soil samples were collected in sandy soils, Arenosols (WRB 2006) from the Doñana National Park (SW Spain) under different vegetation cover: cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Two size fractions; coarse (C: 1-2 mm) and fine (F: 0.05-0.25 mm) were studied from each soil. . In addition, the two fractions from each soil were exhaustively Soxhlet extracted with a Dichlorometane-Methanol (3:1) mixture to obtain the lipid-free fractions (LF) from each size fraction (LFC and LFF). The composition of the organic matter at a molecular level in the different soil fractions was approached by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy. These techniques are complementary and have been found suitable for the structural characterization of complex organic matrices (Moldoveanu, 1998; Piccolo and Stevenson, 1982); whereas Py-GC/MS provides detailed structural information of individual compounds present and a finger-printing of soil organic matter, FT-IR is informative about major functional groups present. The advantages of these techniques are well known: no need for pretreatment are fast to perform, highly reproducible and only small amount of samples are needed. Soil size fractions show contrasting differences in organic matter content (C 4-7 % and F > 40 %) and conspicuous differences were found in the pyrolysis products released by the fractions studied. The main families of pyrolysis compounds have well defined macromolecular precursors, such as lignin, polypeptides, polysaccharides and lipids (González-Vila et al., 2001). The C fractions yield higher relative abundance of lignin and polysaccharide derived pyrolysis compounds. Regarding the differences in the soil organic matter as affected by the different vegetation covers

  14. Potássio nas frações texturais de um Latossolo = Potassium in size fractions of an Oxisol

    Directory of Open Access Journals (Sweden)

    Marcio Koiti Chiba

    2008-10-01

    Full Text Available Este trabalho teve por objetivo estudar a distribuição de formas não-trocáveis de potássio, em frações texturais de um Latossolo cultivado com bananeira, por dois anos, em dois regimes hídricos (parcelas principais, e doses de potássio (0, 300, 600 e 900 kg ha-1(subparcelas, seguindo delineamento em blocos casualizados, com parcelas subdivididas. Verificou-se que os maiores teores de potássio (trocável e não-trocável estão contidos nas frações mais finas: argila e silte. Neste sistema de cultivo e com a aplicação dos adubos na superfície, a movimentação do nutriente, nas camadas estudadas, esteve associada à presença e movimentação da água no perfil do solo. A irrigação desempenhou papel relevante na distribuição das formas do K. Nas parcelas irrigadas, houve mobilização do K até 60 cm deprofundidade. Houve efeitos significativos das doses de potássio nas formas não-trocáveis do nutriente, evidenciando a migração do potássio da solução do solo para o complexo de troca e deste para formas mais fortemente retidas. A quantidade de potássio exportada pela planta foi maior que a variação dos teores trocáveis, indicando que formas não-trocáveis estariam sendo aproveitadas pelas plantas.The aim of this work was to study the distribution of non-exchangeable forms of potassium in different size fractions ofan Oxisol, cultivated with banana for two years in plots with and without irrigation (main plot and varying potassium levels (0, 300, 600 and 900 kg ha-1 of K2O (sub-plots, in a randomized split-plot block design. It was verified that the highest K levels (exchangeableand non-exchangeable forms derived from the finest particle size fractions: clay and silt. The K moving trough soil layers was associated with the presence and action of percolating water in the soil profile. The role of irrigation was significant in the distribution of the different K forms in the soil. Irrigated plots showed the best

  15. Radiation-induced rib fracture after stereotactic body radiotherapy with a total dose of 54-56 Gy given in 9-7 fractions for patients with peripheral lung tumor: impact of maximum dose and fraction size.

    Science.gov (United States)

    Aoki, Masahiko; Sato, Mariko; Hirose, Katsumi; Akimoto, Hiroyoshi; Kawaguchi, Hideo; Hatayama, Yoshiomi; Ono, Shuichi; Takai, Yoshihiro

    2015-04-22

    Radiation-induced rib fracture after stereotactic body radiotherapy (SBRT) for lung cancer has been recently reported. However, incidence of radiation-induced rib fracture after SBRT using moderate fraction sizes with a long-term follow-up time are not clarified. We examined incidence and risk factors of radiation-induced rib fracture after SBRT using moderate fraction sizes for the patients with peripherally located lung tumor. During 2003-2008, 41 patients with 42 lung tumors were treated with SBRT to 54-56 Gy in 9-7 fractions. The endpoint in the study was radiation-induced rib fracture detected by CT scan after the treatment. All ribs where the irradiated doses were more than 80% of prescribed dose were selected and contoured to build the dose-volume histograms (DVHs). Comparisons of the several factors obtained from the DVHs and the probabilities of rib fracture calculated by Kaplan-Meier method were performed in the study. Median follow-up time was 68 months. Among 75 contoured ribs, 23 rib fractures were observed in 34% of the patients during 16-48 months after SBRT, however, no patients complained of chest wall pain. The 4-year probabilities of rib fracture for maximum dose of ribs (Dmax) more than and less than 54 Gy were 47.7% and 12.9% (p = 0.0184), and for fraction size of 6, 7 and 8 Gy were 19.5%, 31.2% and 55.7% (p = 0.0458), respectively. Other factors, such as D2cc, mean dose of ribs, V10-55, age, sex, and planning target volume were not significantly different. The doses and fractionations used in this study resulted in no clinically significant rib fractures for this population, but that higher Dmax and dose per fraction treatments resulted in an increase in asymptomatic grade 1 rib fractures.

  16. Radiation-induced rib fracture after stereotactic body radiotherapy with a total dose of 54–56 Gy given in 9–7 fractions for patients with peripheral lung tumor: impact of maximum dose and fraction size

    International Nuclear Information System (INIS)

    Aoki, Masahiko; Sato, Mariko; Hirose, Katsumi; Akimoto, Hiroyoshi; Kawaguchi, Hideo; Hatayama, Yoshiomi; Ono, Shuichi; Takai, Yoshihiro

    2015-01-01

    Radiation-induced rib fracture after stereotactic body radiotherapy (SBRT) for lung cancer has been recently reported. However, incidence of radiation-induced rib fracture after SBRT using moderate fraction sizes with a long-term follow-up time are not clarified. We examined incidence and risk factors of radiation-induced rib fracture after SBRT using moderate fraction sizes for the patients with peripherally located lung tumor. During 2003–2008, 41 patients with 42 lung tumors were treated with SBRT to 54–56 Gy in 9–7 fractions. The endpoint in the study was radiation-induced rib fracture detected by CT scan after the treatment. All ribs where the irradiated doses were more than 80% of prescribed dose were selected and contoured to build the dose-volume histograms (DVHs). Comparisons of the several factors obtained from the DVHs and the probabilities of rib fracture calculated by Kaplan-Meier method were performed in the study. Median follow-up time was 68 months. Among 75 contoured ribs, 23 rib fractures were observed in 34% of the patients during 16–48 months after SBRT, however, no patients complained of chest wall pain. The 4-year probabilities of rib fracture for maximum dose of ribs (Dmax) more than and less than 54 Gy were 47.7% and 12.9% (p = 0.0184), and for fraction size of 6, 7 and 8 Gy were 19.5%, 31.2% and 55.7% (p = 0.0458), respectively. Other factors, such as D2cc, mean dose of ribs, V10–55, age, sex, and planning target volume were not significantly different. The doses and fractionations used in this study resulted in no clinically significant rib fractures for this population, but that higher Dmax and dose per fraction treatments resulted in an increase in asymptomatic grade 1 rib fractures

  17. Sorption of water vapour by the Na+-exchanged clay-sized fractions of some tropical soil samples

    International Nuclear Information System (INIS)

    Yormah, T.B.R.; Hayes, M.H.B.

    1993-09-01

    Water vapour sorption isotherms at 299K for the Na + -exchanged clay-sized (≤ 2μm e.s.d.) fraction of two sets of samples taken at three different depths from a tropical soil profile have been studied. One set of samples was treated (with H 2 O 2 ) for the removal of much of the organic matter (OM); the other set (of the same samples) was not so treated. The isotherms obtained were all of type II and analyses by the BET method yielded values for the Specific Surface Areas (SSA) and for the average energy of adsorption of the first layer of adsorbate (E a ). OM content and SSA for the untreated samples were found to decrease with depth. Whereas removal of organic matter made negligible difference to the SSA of the top/surface soil, the same treatment produced a significant increase in the SSA of the samples taken from the middle and from the lower depths in the profile; the resulting increase was more pronounced for the subsoil. It has been deduced from these results that OM in the surface soil was less involved with the inorganic soil colloids than that in the subsoil. The increase in surface area which resulted from the removal of OM from the subsoil was most probably due to disaggregation. Values of E a obtained show that for all the samples the adsorption of water vapour became more energetic after the oxidative removal of organic matter; the resulting ΔE a also increased with depth. This suggests that in the dry state, the ''cleaned'' surface of the inorganic soil colloids was more energetic than the ''organic-matter-coater surface''. These data provide strong support for the deduction that OM in the subsoil was in a more ''combined'' state than that in the surface soil. (author). 21 refs, 4 figs, 2 tabs

  18. N-3 polyunsaturated fatty acids improve lipoprotein particle size and concentration in Japanese patients with type 2 diabetes and hypertriglyceridemia: a pilot study.

    Science.gov (United States)

    Ide, Kana; Koshizaka, Masaya; Tokuyama, Hirotake; Tokuyama, Takahiko; Ishikawa, Takahiro; Maezawa, Yoshiro; Takemoto, Minoru; Yokote, Koutaro

    2018-03-15

    Patients with type 2 diabetes are at high risk for cardiovascular disease. Although hydroxymethylglutaryl-CoA reductase inhibitors (statins) can reduce cardiovascular events, residual risk remains even after target low-density lipoprotein cholesterol (LDL-C) levels have been achieved. Lipoprotein particle size and fraction changes are thought to contribute to such risks. The purpose of this study was to evaluate the effects of n-3 polyunsaturated fatty acids (n-3 PUFAs), predominantly eicosapentaenoic acid and docosahexaenoic acid, on lipoprotein particle size, concentration, and glycemic control in Japanese patients with type 2 diabetes and hypertriglyceridemia. This was a multicenter, prospective, open-label, single arm study. We enrolled 14 patients with type 2 diabetes and hypertriglyceridemia treated with statins and dipeptidyl peptidase-4 inhibitors with glycated hemoglobin (HbA1c) n-3 PUFAs for 12 weeks. Lipoprotein particle sizes, concentrations, lipoprotein insulin resistance (LPIR) scores, lipid profiles, HbA1c, and fasting plasma glucose (FPG) were measured before and after treatment. Lipoprotein profiles were measured by nuclear magnetic resonance spectroscopy. Data were analyzed using Wilcoxon signed-rank tests. Concentrations of total cholesterol (P n-3 PUFA administration. N-3 PUFAs decreased the size of very low-density lipoprotein (VLDL; P N-3 PUFAs partly improved atherogenic lipoprotein particle size and concentration, and produced less atherogenic lipoprotein subclass ratios in patients that achieved target LDL-C levels and glycemic control. These results suggest that n-3 PUFAs may reduce residual cardiovascular risk factors in statin-treated patients with type 2 diabetes and hypertriglyceridemia. The study was registered at UMIN-ID: UMIN000013776 .

  19. Physicochemical characterization of titanium dioxide pigments using various techniques for size determination and asymmetric flow field flow fractionation hyphenated with inductively coupled plasma mass spectrometry

    NARCIS (Netherlands)

    Helsper, Hans; Peters, Ruud J.B.; Bemmel, van Greet; Herrera Rivera, Zahira; Wagner, Stephan; Kammer, von der Frank; Tromp, Peter C.; Hofmann, Thilo; Weigel, Stefan

    2016-01-01

    Seven commercial titanium dioxide pigments and two other well-defined TiO2 materials (TiMs) were physicochemically characterised using asymmetric flow field flow fractionation (aF4) for separation, various techniques to determine size distribution and inductively coupled plasma mass

  20. Physicochemical characterization of titanium dioxide pigments using various techniques for size determination and asymmetric flow field flow fractionation hyphenated with inductively coupled plasma mass spectrometry

    NARCIS (Netherlands)

    Helsper, J.P.F.G.; Peters, R.J.B.; Bemmel, M.E.M. van; Rivera, Z.E.H.; Wagner, S.; Kammer, F. von der; Tromp, P.C.; Hofmann, T.; Weigel, S.

    2016-01-01

    Seven commercial titanium dioxide pigments and two other well-defined TiO2 materials (TiMs) were physicochemically characterised using asymmetric flow field flow fractionation (aF4) for separation, various techniques to determine size distribution and inductively coupled plasma mass spectrometry

  1. CONSOLIDATION AND COMPACTION OF POWDER MIXTURES .2. BINARY-MIXTURES OF DIFFERENT PARTICLE-SIZE FRACTIONS OF ALPHA-LACTOSE MONOHYDRATE

    NARCIS (Netherlands)

    RIEPMA, KA; VEENSTRA, J; DEBOER, AH; BOLHUIS, GK; ZUURMAN, K; LERK, CF; VROMANS, H

    1991-01-01

    Binary mixtures of different particle size fractions of alpha-lactose monohydrate were compacted into tablets. The results showed decreased crushing strengths and decreased internal specific surface areas of the tablets as compared with the values calculated by linear interpolation of the data

  2. Nature, distribution and origin of clay minerals in grain size fractions of sediments from manganese nodule field, Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Nath, B.N.

    DT, IR and X-ray diffraction analyses have been carried out on 3 grain size fractions (1, 1-2 and 2-4 mu m) of sediments from the Central Indian Ocean Basin. Results indicate that there are 2 smectite minerals (montmorillonite and Fe...

  3. The heavy metal partition in size-fractions of the fine particles in agricultural soils contaminated by waste water and smelter dust

    International Nuclear Information System (INIS)

    Zhang, Haibo; Luo, Yongming; Makino, Tomoyuki; Wu, Longhua; Nanzyo, Masami

    2013-01-01

    Highlights: ► A continuous flow ultra-centrifugation method has been developed to obtain fine particles from polluted agricultural soil. ► Pollution source affected the heavy metal fractionation in size-fractions by changing soil particle properties. ► The iron oxides affected the distribution of lead species more than other metals in the smelter dust polluted particles. -- Abstract: The partitioning of pollutant in the size-fractions of fine particles is particularly important to its migration and bioavailability in soil environment. However, the impact of pollution sources on the partitioning was seldom addressed in the previous studies. In this study, the method of continuous flow ultra-centrifugation was developed to separate three size fractions (<1 μm, <0.6 μm and <0.2 μm) of the submicron particles from the soil polluted by wastewater and smelter dust respectively. The mineralogy and physicochemical properties of each size-fraction were characterized by X-ray diffraction, transmission electron microscope etc. Total content of the polluted metals and their chemical speciation were measured. A higher enrichment factor of the metals in the fractions of <1 μm or less were observed in the soil contaminated by wastewater than by smelter dust. The organic substance in the wastewater and calcite from lime application were assumed to play an important role in the metal accumulation in the fine particles of the wastewater polluted soil. While the metal accumulation in the fine particles of the smelter dust polluted soil is mainly associated with Mn oxides. Cadmium speciation in both soils is dominated by dilute acid soluble form and lead speciation in the smelter dust polluted soil is dominated by reducible form in all particles. This implied that the polluted soils might be a high risk to human health and ecosystem due to the high bioaccessblity of the metals as well as the mobility of the fine particles in soil

  4. The heavy metal partition in size-fractions of the fine particles in agricultural soils contaminated by waste water and smelter dust

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haibo, E-mail: hbzhang@yic.ac.cn [Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Luo, Yongming, E-mail: ymluo@yic.ac.cn [Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Makino, Tomoyuki [National Institute for Agro-Environmental Sciences, Tsukuba 3058604 (Japan); Wu, Longhua [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Nanzyo, Masami [Tohoku University, Sendai 9808576 (Japan)

    2013-03-15

    Highlights: ► A continuous flow ultra-centrifugation method has been developed to obtain fine particles from polluted agricultural soil. ► Pollution source affected the heavy metal fractionation in size-fractions by changing soil particle properties. ► The iron oxides affected the distribution of lead species more than other metals in the smelter dust polluted particles. -- Abstract: The partitioning of pollutant in the size-fractions of fine particles is particularly important to its migration and bioavailability in soil environment. However, the impact of pollution sources on the partitioning was seldom addressed in the previous studies. In this study, the method of continuous flow ultra-centrifugation was developed to separate three size fractions (<1 μm, <0.6 μm and <0.2 μm) of the submicron particles from the soil polluted by wastewater and smelter dust respectively. The mineralogy and physicochemical properties of each size-fraction were characterized by X-ray diffraction, transmission electron microscope etc. Total content of the polluted metals and their chemical speciation were measured. A higher enrichment factor of the metals in the fractions of <1 μm or less were observed in the soil contaminated by wastewater than by smelter dust. The organic substance in the wastewater and calcite from lime application were assumed to play an important role in the metal accumulation in the fine particles of the wastewater polluted soil. While the metal accumulation in the fine particles of the smelter dust polluted soil is mainly associated with Mn oxides. Cadmium speciation in both soils is dominated by dilute acid soluble form and lead speciation in the smelter dust polluted soil is dominated by reducible form in all particles. This implied that the polluted soils might be a high risk to human health and ecosystem due to the high bioaccessblity of the metals as well as the mobility of the fine particles in soil.

  5. Determination of degradation rates of organic substances in the unsaturated soil zone depending on the grain size fractions of various soil types

    Science.gov (United States)

    Fichtner, Thomas; Stefan, Catalin; Goersmeyer, Nora

    2015-04-01

    Rate and extent of the biological degradation of organic substances during transport through the unsaturated soil zone is decisively influenced by the chemical and physical properties of the pollutants such as water solubility, toxicity and molecular structure. Furthermore microbial degradation processes are also influenced by soil-specific properties. An important parameter is the soil grain size distribution on which the pore volume and the pore size depends. Changes lead to changes in air and water circulation as well as preferred flow paths. Transport capacity of water inclusive nutrients is lower in existing bad-drainable fine pores in soils with small grain size fractions than in well-drainable coarse pores in a soil with bigger grain size fractions. Because fine pores are saturated with water for a longer time than the coarse pores and oxygen diffusion in water is ten thousand times slower than in air, oxygen is replenished much slower in soils with small grain size fractions. As a result life and growth conditions of the microorganisms are negatively affected. This leads to less biological activity, restricted degradation/mineralization of pollutants or altered microbial processes. The aim of conducted laboratory column experiments was to study the correlation between the grain size fractions respectively pore sizes, the oxygen content and the biodegradation rate of infiltrated organic substances. Therefore two columns (active + sterile control) were filled with different grain size fractions (0,063-0,125 mm, 0,2-0,63 mm and 1-2 mm) of soils. The sterile soil was inoculated with a defined amount of a special bacteria culture (sphingobium yanoikuae). A solution with organic substances glucose, oxalic acid, sinaphylic alcohol and nutrients was infiltrated from the top in intervals. The degradation of organic substances was controlled by the measurement of dissolved organic carbon in the in- and outflow of the column. The control of different pore volumes

  6. Upper limits to americium concentration in large sized sodium-cooled fast reactors loaded with metallic fuel

    International Nuclear Information System (INIS)

    Zhang, Youpeng; Wallenius, Janne

    2014-01-01

    Highlights: • The americium transmutation capability of Integral Fast Reactor was investigated. • The impact from americium introduction was parameterized by applying SERPENT Monte Carlo calculations. • Higher americium content in metallic fuel leads to a power penalty, preserving consistent safety margins. - Abstract: Transient analysis of a large sized sodium-cooled reactor loaded with metallic fuel modified by different fractions of americium have been performed. Unprotected loss-of-offsite power, unprotected loss-of-flow and unprotected transient-over-power accidents were simulated with the SAS4A/SASSYS code based on the geometrical model of an IFR with power rating of 2500 MW th , using safety parameters obtained with the SERPENT Monte Carlo code. The Ti-modified austenitic D9 steel, having higher creep rupture strength, was considered as the cladding and structural material apart from the ferritic/martensitic HT9 steel. For the reference case of U–12Pu–1Am–10Zr fuel at EOEC, the margin to fuel melt during a design basis condition UTOP is about 50 K for a maximum linear rating of 30 kW/m. In order to maintain a margin of 50 K to fuel failure, the linear power rating has to be reduced by ∼3% and 6% for 2 wt.% and 3 wt.% Am introduction into the fuel respectively. Hence, an Am concentration of 2–3 wt.% in the fuel would lead to a power penalty of 3–6%, permitting a consumption rate of 3.0–5.1 kg Am/TW h th . This consumption rate is significantly higher than the one previously obtained for oxide fuelled SFRs

  7. Variability of sub-micrometer particle number size distributions and concentrations in the Western Mediterranean regional background

    Directory of Open Access Journals (Sweden)

    Michael Cusack

    2013-02-01

    Full Text Available This study focuses on the daily and seasonal variability of particle number size distributions and concentrations, performed at the Montseny (MSY regional background station in the western Mediterranean from October 2010 to June 2011. Particle number concentrations at MSY were shown to be within range of various other sites across Europe reported in literature, but the seasonality of the particle number size distributions revealed significant differences. The Aitken mode is the dominant particle mode at MSY, with arithmetic mean concentrations of 1698 cm3, followed by the accumulation mode (877 cm−3 and the nucleation mode (246 cm−3. Concentrations showed a strong seasonal variability with large increases in particle number concentrations observed from the colder to warmer months. The modality of median size distributions was typically bimodal, except under polluted conditions when the size distribution was unimodal. During the colder months, the daily variation of particle number size distributions are strongly influenced by a diurnal breeze system, whereby the Aitken and accumulation modes vary similarly to PM1 and BC mass concentrations, with nocturnal minima and sharp day-time increases owing to the development of a diurnal mountain breeze. Under clean air conditions, high levels of nucleation and lower Aitken mode concentrations were measured, highlighting the importance of new particle formation as a source of particles in the absence of a significant condensation sink. During the warmer months, nucleation mode concentrations were observed to be relatively elevated both under polluted and clean conditions due to increased photochemical reactions, with enhanced subsequent growth owing to elevated concentrations of condensable organic vapours produced from biogenic volatile organic compounds, indicating that nucleation at MSY does not exclusively occur under clean air conditions. Finally, mixing of air masses between polluted and non

  8. Influence of ST-segment recovery on infarct size and ejection fraction in patients with ST-segment elevation myocardial infarction receiving primary percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Hallén, Jonas; Ripa, Maria Sejersten; Johanson, Per

    2010-01-01

    percutaneous coronary intervention. Three methods for calculating and categorizing ST-segment recovery were used: (1) summed ST-segment deviation (STD) resolution analyzed in 3 categories (> or = 70%, > or = 30% to or = 2 mm). Infarct size and ejection fraction were assessed at 4 months by cardiac magnetic...... resonance imaging. All 3 ST-segment recovery algorithms predicted the final infarct size and cardiac function. Worst-lead residual STD performed the same as, or better than, the more complex methods and identified large subgroups at either end of the risk spectrum (median infarct size from the lowest...

  9. 14C-labeled organic amendments: Characterization in different particle size fractions and humic acids in a long-term field experiment.

    Science.gov (United States)

    Tatzber, Michael; Stemmer, Michael; Spiegel, Heide; Katzlberger, Christian; Landstetter, Claudia; Haberhauer, Georg; Gerzabek, Martin H

    2012-05-01

    Knowledge about the stabilization of organic matter input to soil is essential for understanding the influence of different agricultural practices on turnover characteristics in agricultural soil systems. In this study, soil samples from a long-term field experiment were separated into silt- and clay-sized particles. In 1967, 14 C labeled farmyard manure was applied to three different cropping systems: crop rotation, monoculture and permanent bare fallow. Humic acids (HAs) were extracted from silt- and clay-sized fractions and characterized using photometry, mid-infrared and fluorescence spectroscopy. Remaining 14 C was determined in size fractions as well as in their extracted HAs. Yields of carbon and remaining 14 C in HAs from silt-sized particles and C org in clay-sized particles decreased significantly in the order: crop rotation > monoculture ≫ bare fallow. Thus, crop rotation not only had the largest overall C-pool in the experiment, but it also best stabilized the added manure. Mid-infrared spectroscopy could distinguish between HAs from different particle size soil fractions. With spectroscopic methods significant differences between the cropping systems were detectable in fewer cases compared to quantitative results of HAs (yields, 14 C, C org and N t ). The trends, however, pointed towards increased humification of HAs from bare fallow systems compared to crop rotation and monoculture as well as of HAs from clay-sized particles compared to silt-sized particles. Our study clearly shows that the largest differences were observed between bare fallow on one hand and monoculture and crop rotation on the other.

  10. Emulsion Polymerization of Etyl Acrylate: The Effect of Surfactant, Initiator Concentration and PolymerizationTechnique on Particle Size Distribution

    Directory of Open Access Journals (Sweden)

    Nitri Arinda

    2009-04-01

    Full Text Available Emulsion polymerization was conducted using ethyl acrylate monomer. Theeffect of sodium lauryl sulfate concentration, ammonium persulfate concentration, the various of polymerizationtechniques and feeding time to the conversion, particle size and its distribution were observed. The purpose of thisresearch is to obtain the optimum condition of ethyl acrylate homopolymer with particle size around 100 nm, to get theparticle size distribution monodisperse and to get solid content value of the experiment closed to its theoretical value.The optimum condition then could be applied in shell polymerization of core-shell polymers. The results of the researchshowed that semicontinuous technique obtained optimum sodium lauryl sulfate concentration at 20 CMC (criticalmicelle concentration and ammonium persulfate concentration is 3%. By using batch technique that the biggestparticle size is 123 nm with conversion 95.8% and monodisperse. The shorter of feeding time the more monomer ofethyl acrylate being polymerized, it is showed by the higher conversion up to 94.4% and the bigger particle size is107.9 nm.

  11. Incorporation of inorganic mercury (Hg²⁺) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: the role of different plankton size fractions and species assemblages.

    Science.gov (United States)

    Soto Cárdenas, Carolina; Diéguez, Maria C; Ribeiro Guevara, Sergio; Marvin-DiPasquale, Mark; Queimaliños, Claudia P

    2014-10-01

    In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg(2+)) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg(2+) by four plankton fractions (picoplankton: 0.2-2.7 μm; pico+nanoplankton: 0.2-20 μm; microplankton: 20-50 μm; and mesoplankton: 50-200 μm) obtained from four Andean Patagonian lakes, using the radioisotope (197)Hg(2+). Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg(2+) in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico+nanoplankton play a central role leading the incorporation of Hg(2+) in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg(2+) by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria-nanoflagellates-crustaceans; bacteria-ciliates-crustaceans; endosymbiotic algae-ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg(2+) observed in all the plankton fractions. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. A new approach to estimate the in situ fractional degradation rate of organic matter and nitrogen in wheat yeast concentrates

    NARCIS (Netherlands)

    De Jonge, L. H.; Van Laar, H.; Hendriks, W. H.; Dijkstra, J.

    2015-01-01

    In the classic in situ method, small particles are removed during rinsing and hence their fractional degradation rate cannot be determined. A new approach was developed to estimate the fractional degradation rate of nutrients in small particles. This approach was based on an alternative rinsing

  13. How do changes in suspended sediment concentration alone influence the size of mud flocs under steady turbulent shearing?

    Science.gov (United States)

    Tran, Duc; Kuprenas, Rachel; Strom, Kyle

    2018-04-01

    Modeling the size and settling velocity of sediment under the influence of flocculation is crucial for the accurate prediction of mud movement and deposition in sediment transport modeling of environments such as agricultural streams, large coastal rivers, estuaries, river plumes, and turbidity currents. Yet, collecting accurate and high resolution data on mud flocs is difficult. As a result, models that account for the influence of flocculation on mud settling velocity are based on sparse data that often present non-congruent relationship in floc properties with basic influencers of flocculations such as suspended sediment concentration. This study examines the influence of suspended sediment concentration on floc size populations within a turbulent suspension. Specifically, the work investigates: (1) the relationship between the equilibrium floc size and suspended sediment concentration under conditions of steady concentration and turbulent shearing; and (2) the speed at which mature flocs adapt to an unsteady drop in the concentration when turbulent shear is constant. Two sets of experiments were used to investigate the target processes. All work was conducted in laboratory mixing tanks using a floc camera and a newly developed image acquisition method. The new method allows for direct imaging and sizing of flocs within turbulent suspensions of clay in concentrations ranging from 15 to 400 mg/L, so that no transfer of the sample to another settling column or imaging tank is needed. The primary conclusions from the two sets of experiments are: (1) that the equilibrium floc size in an energetic turbulent suspension is linearly and positively related to concentration over the range of C = 50 to 400 mg/L, yet with a smaller-than-expected slope based on previous data and models from low-energy environments; and (2) that floc sizes decrease quickly (with a time lag on the order of 1-15 min) to time-varying decreases in concentration at turbulent shearing of G = 50s-1

  14. Monsoon-induced changes in the size-fractionated phytoplankton biomass and production rate in the estuarine and coastal waters of southwest coast of India.

    Science.gov (United States)

    Madhu, N V; Jyothibabu, R; Balachandran, K K

    2010-07-01

    Changes in the autotrophic pico- (0.2-2 microm), nano- (2-20 microm), and microplankton (>20 microm) biomass (chlorophyll a) and primary production were measured in the estuarine and coastal waters off Cochin, southwest coast of India during the onset and establishment of a monsoon. During this period, the estuary was dominated by nutrient-rich freshwater, whereas the coastal waters were characterized with higher salinity values (>30 psu) and less nutrients. The average surface chlorophyll a concentrations and primary production rates were higher in the estuary (average 13.7 mg m(-3) and 432 mgC m(-3) day(-1)) as compared to the coastal waters (5.3 mg m(-3) and 224 mgC m(-3) day(-1)). The nanoplankton community formed the major fraction of chlorophyll a and primary production, both in the estuary (average 85 +/- SD 8.3% and 81.2 +/- SD 3.2%) and the coastal waters (average 73.2 +/- SD 17.2% and 81.9 +/- 15.7%). Nanoplankton had the maximum photosynthetic efficiency in the coastal waters (average 4.8 +/- SD 3.9 mgC mgChl a m(-3) h(-1)), whereas in the estuary, the microplankton had higher photosynthetic efficiency (average 7.4 +/- 7 mgC mgChl a m(-3) h(-1)). The heavy cloud cover and increased water column turbidity not only limit the growth of large-sized phytoplankton in the Cochin estuary and coastal waters but also support the proliferation of nanoplankton community during the monsoon season, even though large variation in nanoplankton chlorophyll a and production exists between these two areas.

  15. Wildfire effects on lipid composition and hydrophobicity of bulk soil and soil size fractions under Quercus suber cover (SW-Spain).

    Science.gov (United States)

    Jiménez-Morillo, Nicasio T; Spangenberg, Jorge E; Miller, Ana Z; Jordán, Antonio; Zavala, Lorena M; González-Vila, Francisco J; González-Pérez, José A

    2017-11-01

    Soil water repellency (hydrophobicity) prevents water from wetting or infiltrating soils, triggering changes in the ecosystems. Fire may develop, enhance or destroy hydrophobicity in previously wettable or water-repellent soils. Soil water repellency is mostly influenced by the quality and quantity of soil organic matter, particularly the lipid fraction. Here we report the results of a study on the effect of fire on the distribution of soil lipids and their role in the hydrophobicity grade of six particle size fractions (2-1, 1-0.5, 0.5-0.25, 0.25-0.1, 0.1-0.05 and fractions. Soil lipids were Soxhlet extracted with a dichloromethane-methanol mixture. Fatty acids (FAs) and neutral lipids were separated, derivatized, identified and quantified by gas chromatography/mass spectrometry and gas chromatography/flame ionization detection. The hydrophobicity values of soil samples and fractions were statistically different (P fractions. All samples displayed a similar distribution of FAs, straight-chain saturated acids in the C 14 -C 32 range, and neutral lipids (n-alkan-1-ols, n-alkanes), only differing in their relative abundances. Among possible biogeochemical mechanisms responsible for the changes in soil lipids, the observed depletion of long chain FAs (C ≥24 ) in the coarse fraction is best explained by thermal cracking caused by the heat of the fire. The enrichment of long chain FAs observed in other fractions suggests possible exogenous additions of charred, lipid-rich, material, like cork suberin or other plant-derived macromolecules (cutins). Principal component analysis was used to study the relationships between hydrophobicity with soil organic matter and its different components. Extractable organic matter (EOM) and specifically long chain FAs content were positively correlated to soil hydrophobicity. Therefore, the latter could be used as biomarkers surrogated to hydrophobicity in sandy soils. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Changes in the concentration of iron in different size fractions during an iron enrichment experiment in the open Southern Ocean

    NARCIS (Netherlands)

    Nishioka, Jun; Takeda, Shigenobu; Baar, Hein J.W. de; Croot, Peter L.; Boye, Marie; Laan, Patrick; Timmermans, Klaas R.

    2005-01-01

    An in situ iron enrichment experiment was carried out in the Southern Ocean Polar Frontal Zone and fertilized a patch of water within an eddy of the Antarctic Circumpolar Current (EisenEx, Nov. 2000). During the experiment, a physical speciation technique was used for iron analysis in order to

  17. Incorporation of inorganic mercury (Hg2+) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: The role of different plankton size fractions and species assemblages

    International Nuclear Information System (INIS)

    Soto Cárdenas, Carolina; Diéguez, Maria C.; Ribeiro Guevara, Sergio; Marvin-DiPasquale, Mark; Queimaliños, Claudia P.

    2014-01-01

    In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg 2+ ) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg 2+ by four plankton fractions (picoplankton: 0.2–2.7 μm; pico + nanoplankton: 0.2–20 μm; microplankton: 20–50 μm; and mesoplankton: 50–200 μm) obtained from four Andean Patagonian lakes, using the radioisotope 197 Hg 2+ . Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg 2+ in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico + nanoplankton play a central role leading the incorporation of Hg 2+ in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg 2+ by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria–nanoflagellates–crustaceans; bacteria–ciliates–crustaceans; endosymbiotic algae–ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg 2+ observed in all the plankton fractions. - Highlights: • Hg 2+ incorporation in lake plankton fractions was studied using the isotope 197 Hg 2+ . • Hg 2+ incorporation was assessed using three different

  18. Incorporation of inorganic mercury (Hg{sup 2+}) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: The role of different plankton size fractions and species assemblages

    Energy Technology Data Exchange (ETDEWEB)

    Soto Cárdenas, Carolina, E-mail: sotocardenascaro@gmail.com [Laboratorio de Fotobiología, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400 San Carlos de Bariloche, Río Negro (Argentina); Diéguez, Maria C. [Laboratorio de Fotobiología, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400 San Carlos de Bariloche, Río Negro (Argentina); Ribeiro Guevara, Sergio [Laboratorio de Análisis por Activación Neutrónica, CAB, CNEA, Av. Bustillo Km 9.5, 8400, San Carlos de Bariloche, Río Negro (Argentina); Marvin-DiPasquale, Mark [United States Geological Survey, 345 Middlefield Rd./MS 480, Menlo Park, CA 94025 (United States); Queimaliños, Claudia P. [Laboratorio de Fotobiología, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400 San Carlos de Bariloche, Río Negro (Argentina)

    2014-10-01

    In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg{sup 2+}) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg{sup 2+} by four plankton fractions (picoplankton: 0.2–2.7 μm; pico + nanoplankton: 0.2–20 μm; microplankton: 20–50 μm; and mesoplankton: 50–200 μm) obtained from four Andean Patagonian lakes, using the radioisotope {sup 197}Hg{sup 2+}. Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg{sup 2+} in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico + nanoplankton play a central role leading the incorporation of Hg{sup 2+} in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg{sup 2+} by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria–nanoflagellates–crustaceans; bacteria–ciliates–crustaceans; endosymbiotic algae–ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg{sup 2+} observed in all the plankton fractions. - Highlights: • Hg{sup 2+} incorporation in lake plankton fractions was studied using the isotope {sup 197}Hg{sup 2+}. • Hg{sup 2

  19. Sensitivity of cloud albedo to aerosol concentration and spectral dispersion of cloud droplet size distribution

    Energy Technology Data Exchange (ETDEWEB)

    Iorga, G. [Faculty of Chemistry, University of Bucharest, Bucharest (Romania)]. E-mail: giorga@gw-chimie.math.unibuc.ro; Stefan, S. [Faculty of Physics, University of Bucharest, Bucharest (Romania)

    2007-07-15

    Both the enhancement of the aerosol number concentration and the relative dispersion of the cloud droplet size distribution (spectral dispersion) on a regional scale can modify the cloud reflectivity. This work is focused on the role that pre-cloud aerosol plays in cloud reflectivity. Log-normal aerosol size distributions were used to describe two aerosol types: marine and rural. The number of aerosols that activate to droplets was obtained based on Abdul-Razzak and Ghan's (2000) activation parameterization. The cloud albedo taking into account the spectral dispersion effect in the parameterization of cloud effective radius and in the scattering asymmetry factor has been estimated. Two different scaling factors to account for dispersion were used. The sensitivity of cloud albedo to spectral dispersion-cloud droplet number concentration relationship in connection to the changes in liquid water content (LWC), and the cloud droplet effective radius has been also investigated. We obtained higher values of effective radius when dispersion is taken into account, with respect to the base case (without considering dispersion). The inferred absolute differences in effective radius values between calculations with each of the scaling factors are below 0.8 {mu}m as LWC ranges between 0.1 and 1.0 g m-3. The optical depth decreased by up to 14% (marine), and up to 29% (continental) when dispersion is considered in both effective radius and asymmetry factor ({beta}LDR scaling factor). Correspondingly, the relative change in cloud albedo is up to 6% (marine) and up to 11% (continental) clouds. For continental clouds, the calculated effective radius when dispersion is considered fits well within the measured range of effective radius in SCAR-B project. The calculated cloud albedo when dispersion is considered shows better agreement with the estimated cloud albedo from measured effective radius in SCAR-B project than the cloud albedo calculated without dispersion. In cleaner

  20. An optimum city size? The scaling relationship for urban population and fine particulate (PM_2_._5) concentration

    International Nuclear Information System (INIS)

    Han, Lijian; Zhou, Weiqi; Pickett, Steward T.A.; Li, Weifeng; Li, Li

    2016-01-01

    We utilize the distribution of PM_2_._5 concentration and population in large cities at the global scale to illustrate the relationship between urbanization and urban air quality. We found: 1) The relationship varies greatly among continents and countries. Large cities in North America, Europe, and Latin America have better air quality than those in other continents, while those in China and India have the worst air quality. 2) The relationships between urban population size and PM_2_._5 concentration in large cities of different continents or countries were different. PM_2_._5 concentration in large cities in North America, Europe, and Latin America showed little fluctuation or a small increasing trend, but those in Africa and India represent a “U” type relationship and in China represent an inverse “U” type relationship. 3) The potential contribution of population to PM_2_._5 concentration was higher in the large cities in China and India, but lower in other large cities. - Highlights: • Urban population and PM_2_._5 concentration varies greatly among regions. • Urban population size increase does not always enhances PM_2_._5 concentration. • Population's potential contribution to PM_2_._5 concentration higher in China. - We utilize the distribution of PM_2_._5 concentration and population in large cities at the global scale to illustrate the relationship between urbanization and urban air quality.

  1. Bacterial community composition of size-fractioned aggregates within the phycosphere of cyanobacterial blooms in a eutrophic freshwater lake.

    Directory of Open Access Journals (Sweden)

    Haiyuan Cai

    Full Text Available Bacterial community composition of different sized aggregates within the Microcystis cyanobacterial phycosphere were determined during summer and fall in Lake Taihu, a eutrophic lake in eastern China. Bloom samples taken in August and September represent healthy bloom biomass, whereas samples from October represent decomposing bloom biomass. To improve our understanding of the complex interior structure in the phycosphere, bloom samples were separated into large (>100 µm, medium (10-100 µm and small (0.2-10 µm size aggregates. Species richness and library coverage indicated that pyrosequencing recovered a large bacterial diversity. The community of each size aggregate was highly organized, indicating highly specific conditions within the Microcystis phycosphere. While the communities of medium and small-size aggregates clustered together in August and September samples, large- and medium-size aggregate communities in the October sample were grouped together and distinct from small-size aggregate community. Pronounced changes in the absolute and relative percentages of the dominant genus from the two most important phyla Proteobacteria and Bacteroidetes were observed among the various size aggregates. Bacterial species on large and small-size aggregates likely have the ability to degrade high and low molecular weight compounds, respectively. Thus, there exists a spatial differentiation of bacterial taxa within the phycosphere, possibly operating in sequence and synergy to catalyze the turnover of complex organic matters.

  2. Toxicologically important trace elements and organic compounds investigated in size-fractionated urban particulate matter collected near the Prague highway

    Czech Academy of Sciences Publication Activity Database

    Sysalová, J.; Sýkorová, Ivana; Havelcová, Martina; Száková, J.; Trejtnarová, Hana; Kotlík, B.

    2012-01-01

    Roč. 437, October (2012), s. 127-136 ISSN 0048-9697 R&D Projects: GA ČR GA205/09/1162 Institutional support: RVO:67985891 Keywords : urban particulate matter * grain- size partitioning * grain- size partitioning Subject RIV: DI - Air Pollution ; Quality Impact factor: 3.258, year: 2012

  3. Effect of traffic restriction on atmospheric particle concentrations and their size distributions in urban Lanzhou, Northwestern China.

    Science.gov (United States)

    Zhao, Suping; Yu, Ye; Liu, Na; He, Jianjun; Chen, Jinbei

    2014-02-01

    During the 2012 Lanzhou International Marathon, the local government made a significant effort to improve traffic conditions and air quality by implementing traffic restriction measures. To evaluate the direct effect of these measures on urban air quality, especially particle concentrations and their size distributions, atmospheric particle size distributions (0.5-20 microm) obtained using an aerodynamic particle sizer (model 3321, TSI, USA) in June 2012 were analyzed. It was found that the particle number, surface area and volume concentrations for size range 0.5-10 microm were (15.0 +/- 2.1) cm(-3), (11.8 +/- 2.6) microm2/cm3 and (1.9 +/- 0.6) microm2/cm3, respectively, on the traffic-restricted day (Sunday), which is 63.2%, 53.0% and 47.2% lower than those on a normal Sunday. For number and surface area concentrations, the most affected size range was 0.5-0.7 and 0.5-0.8 microm, respectively, while for volume concentration, the most affected size ranges were 0.5-0.8, 1.7-2.0 and 5.0-5.4 microm. Number and volume concentrations of particles in size range 0.5-1.0 microm correlated well with the number of non-CNG (Compressed Natural Gas) powered vehicles, while their correlation with the number of CNG-powered vehicles was very low, suggesting that reasonable urban traffic controls along with vehicle technology improvements could play an important role in improving urban air quality.

  4. Determining the size and concentration dependence of gold nanoparticles in vitro cytotoxicity (IC50) test using WST-1 assay

    International Nuclear Information System (INIS)

    Rosli, Nur Shafawati binti; Rahman, Azhar Abdul; Aziz, Azlan Abdul; Shamsuddin, Shaharum

    2015-01-01

    Gold nanoparticles (AuNPs) received a great deal of attention for biomedical applications, especially in diagnostic imaging and therapeutics. Even though AuNPs have potential benefits in biomedical applications, the impact of AuNPs on human and environmental health still remains unclear. The use of AuNPs which is a high-atomic-number materials, provide advantages in terms of radiation dose enhancement. However, before this can become a clinical reality, cytotoxicity of the AuNPs has to be carefully evaluated. Cytotoxicity test is a rapid, standardized test that is very sensitive to determine whether the nanoparticles produced are harmful or benign on cellular components. In this work the size and concentration dependence of AuNPs cytotoxicity in breast cancer cell lines (MCF-7) are tested by using WST-1 assay. The sizes of AuNPs tested were 13 nm, 50 nm, and 70 nm. The cells were seeded in the 96-well plate and were treated with different concentrations of AuNPs by serial dilution for each size of AuNPs. The high concentration of AuNPs exhibit lower cell viability compared to low concentration of AuNPs. We quantified the toxicity of AuNPs in MCF-7 cell lines by determining the IC 50 values in WST-1 assays. The IC 50 values (inhibitory concentrations that effected 50% growth inhibition) of 50 nm AuNPs is lower than 13 nm and 70 nm AuNPs. Mean that, 50nm AuNPs are more toxic to the MCF-7 cells compared to smaller and larger sizes AuNPs. The presented results clearly indicate that the cytotoxicity of AuNPs depend not only on the concentration, but also the size of the nanoparticles

  5. Optimizing concentration of shifter additive for plastic scintillators of different size

    Science.gov (United States)

    Adadurov, A. F.; Zhmurin, P. N.; Lebedev, V. N.; Titskaya, V. D.

    2009-02-01

    This paper concerns the influence of wavelength shifting (secondary) luminescent additive (LA 2) on the light yield of polystyrene-based plastic scintillator (PS) taking self-absorption into account. Calculations of light yield dependence on concentration of 1.4-bis(2-(5-phenyloxazolyl)-benzene (POPOP) as LA 2 were made for various path lengths of photons in PS. It is shown that there is an optimal POPOP concentration ( Copt), which provides a maximum light yield for a given path length. This optimal concentration is determined by the competition of luminescence and self-reflection processes. Copt values were calculated for PS of different dimensions. For small PS, Copt≈0.02%, which agree with a common (standard) value of POPOP concentration. For higher PS dimensions, the optimal POPOP concentration is decreased (to Copt≈0.006% for 320×30×2 cm sample), reducing the light yield from PS by almost 35%.

  6. Total and size-resolved particle number and black carbon concentrations in urban areas near Schiphol airport (the Netherlands)

    NARCIS (Netherlands)

    Keuken, M.P.; Moerman, M.; Zandveld, P.; Henzing, J.S.; Hoek, G.

    2015-01-01

    The presence of black carbon, and size-resolved and total particle number concentrations (PNC) were investigated in the vicinity of Schiphol airport in the Netherlands, the fourth busiest airport in Europe. Continuous measurements were conducted between March and May 2014at Adamse Bos, located 7km

  7. Angular reflectance of suspended gold, aluminum and silver nanospheres on a gold film: Effects of concentration and size distribution

    International Nuclear Information System (INIS)

    Aslan, Mustafa M.; Wriedt, Thomas

    2010-01-01

    In this article, we describe a parametric study of the effects of the size distribution (SD) and the concentration of nanospheres in ethanol on the angular reflectance. Calculations are based on an effective medium approach in which the effective dielectric constant of the mixture is obtained using the Maxwell-Garnett formula. The detectable size limits of gold, aluminum, and silver nanospheres on a 50-nm-thick gold film are calculated to investigate the sensitivity of the reflectance to the SD and the concentration of the nanospheres. The following assumptions are made: (1) the total number of particles in the unit volume of suspension is constant, (2) the nanospheres in the suspension on a gold film have a SD with three different concentrations, and (3) there is no agglomeration and the particles have a log-normal SD, where the effective diameter, d eff and the effective variance, ν eff are given. The dependence of the reflectance on the d eff , ν eff , and the width of the SD are also investigated numerically. The angular variation of the reflectance as a function of the incident angle shows a strong dependence on the effective size of the metallic nanospheres. The results confirm that the size of the nanospheres (d eff o and 75 o for a given concentration with a particular SD.

  8. Determining the most effective concentration of cypermethrin and the appropriate carrier particle size for fire ant (Hymenoptera: Formicidae) bait.

    Science.gov (United States)

    Kafle, Lekhnath; Shih, Cheng-Jen

    2012-03-01

    The purpose of this study was to determine the most effective particle size of DDGS (distiller's dried grains with solubles) as fire ant bait carrier, as well as the most effective concentration of cypermethrin as a toxicant against the red imported fire ant (RIFA) Solenopsis invicta Buren under laboratory conditions. The DDGS particle size did not affect the fire ant's preference for the bait, but it did affect the mass of DDGS being carried back to the nest. The size of the DDGS particles and the mass of DDGS being carried back to the nest were positively correlated. The most efficient particle size of DDGS was 0.8-2 mm. The concentration of cypermethrin has a specific range for killing fire ants in an efficient manner. Neither a very low nor a very high concentration of cypermethrin was able to kill fire ants efficiently. The most effective concentration of cypermethrin was 0.13% in DDGS when mixed with 15% shrimp shell powders and 11% soybean oil. Based on its ability to kill fire ants when mixed with cypermethrin, as well as the advantage of having a larger area coverage when sprayed in the field, DDGS as the carrier and cypermethrin as the toxicant can be considered to be an efficient way to prepare fire ant bait for controlling fire ants in infested areas. Copyright © 2012 Society of Chemical Industry.

  9. Structural and Dynamical Properties of Alkaline Earth Metal Halides in Supercritical Water: Effect of Ion Size and Concentration.

    Science.gov (United States)

    Keshri, Sonanki; Tembe, B L

    2017-11-22

    Constant temperature-constant pressure molecular dynamics simulations have been performed for aqueous alkaline earth metal chloride [M 2+ -Cl - (M = Mg, Ca, Sr, and Ba)] solutions over a wide range of concentrations (0.27-5.55 m) in supercritical (SC) and ambient conditions to investigate their structural and dynamical properties. A strong influence of the salt concentration is observed on the ion-ion pair correlation functions in both ambient and SC conditions. In SC conditions, significant clustering is observed in the 0.27 m solution, whereas the reverse situation is observed at room temperature and this is also supported by the residence times of the clusters. The concentration and ion size (cation size) seem to have opposite effects on the average number of hydrogen bonds. The simulation results show that the self-diffusion coefficients of water, cations, and the chloride ion increase with increasing temperature, whereas they decrease with increasing salt concentration. The cluster size distribution shows a strong density dependence in both ambient and SC conditions. In SC conditions, cluster sizes display a near-Gaussian distribution, whereas the distribution decays monotonically in ambient conditions.

  10. Correlation of Air Quality Data to Ultrafine Particles (UFP Concentration and Size Distribution in Ambient Air

    Directory of Open Access Journals (Sweden)

    Werner Hofmann

    2010-07-01

    Full Text Available This study monitored ultrafine particles (UFP concurrent with environmental air quality data, investigating whether already existing instrumentation used by environmental authorities can provide reference values for estimating UFP concentrations. Of particular interest was the relation of UFP to PM10 (particulate matter and nitrogen oxides (NOx, NO2 in ambient air. Existing PM measurement methods alone did not correspond exactly enough with the actual particle number, but we observed a link between NOx and NO2 to UFP concentration. The combined data could act as proxy-indicator for authorities in estimating particle number concentrations, but cannot replace UFP monitoring.

  11. Size-fractionated characterization and quantification of nanoparticle release rates from a consumer spray product containing engineered nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hagendorfer, Harald, E-mail: Harald.Hagendorfer@empa.c [EMPA, Swiss Federal Laboratories for Materials Testing and Research (Switzerland); Lorenz, Christiane, E-mail: Christiane.Lorenz@chem.ethz.c [ETHZ, Swiss Federal Institute of Technology Zurich (Switzerland); Kaegi, Ralf, E-mail: Ralf.Kaegi@eawag.ch; Sinnet, Brian, E-mail: Brian.Sinnet@eawag.c [EAWAG, Swiss Federal Institute of Aquatic Science and Technology (Switzerland); Gehrig, Robert, E-mail: Robert.Gehrig@empa.c [EMPA, Swiss Federal Laboratories for Materials Testing and Research (Switzerland); Goetz, Natalie V., E-mail: Natalie.vonGoetz@chem.ethz.ch; Scheringer, Martin, E-mail: Martin.Scheringer@chem.ethz.c [ETHZ, Swiss Federal Institute of Technology Zurich (Switzerland); Ludwig, Christian, E-mail: Christian.Ludwig@psi.c [PSI, Paul Scherrer Institue (Switzerland); Ulrich, Andrea, E-mail: Andrea.Ulrich@empa.c [EMPA, Swiss Federal Laboratories for Materials Testing and Research (Switzerland)

    2010-09-15

    This study describes methods developed for reliable quantification of size- and element-specific release of engineered nanoparticles (ENP) from consumer spray products. A modified glove box setup was designed to allow controlled spray experiments in a particle-minimized environment. Time dependence of the particle size distribution in a size range of 10-500 nm and ENP release rates were studied using a scanning mobility particle sizer (SMPS). In parallel, the aerosol was transferred to a size-calibrated electrostatic TEM sampler. The deposited particles were investigated using electron microscopy techniques in combination with image processing software. This approach enables the chemical and morphological characterization as well as quantification of released nanoparticles from a spray product. The differentiation of solid ENP from the released nano-sized droplets was achieved by applying a thermo-desorbing unit. After optimization, the setup was applied to investigate different spray situations using both pump and gas propellant spray dispensers for a commercially available water-based nano-silver spray. The pump spray situation showed no measurable nanoparticle release, whereas in the case of the gas spray, a significant release was observed. From the results it can be assumed that the homogeneously distributed ENP from the original dispersion grow in size and change morphology during and after the spray process but still exist as nanometer particles of size <100 nm. Furthermore, it seems that the release of ENP correlates with the generated aerosol droplet size distribution produced by the spray vessel type used. This is the first study presenting results concerning the release of ENP from spray products.

  12. Size-fractionated characterization and quantification of nanoparticle release rates from a consumer spray product containing engineered nanoparticles

    International Nuclear Information System (INIS)

    Hagendorfer, Harald; Lorenz, Christiane; Kaegi, Ralf; Sinnet, Brian; Gehrig, Robert; Goetz, Natalie V.; Scheringer, Martin; Ludwig, Christian; Ulrich, Andrea

    2010-01-01

    This study describes methods developed for reliable quantification of size- and element-specific release of engineered nanoparticles (ENP) from consumer spray products. A modified glove box setup was designed to allow controlled spray experiments in a particle-minimized environment. Time dependence of the particle size distribution in a size range of 10-500 nm and ENP release rates were studied using a scanning mobility particle sizer (SMPS). In parallel, the aerosol was transferred to a size-calibrated electrostatic TEM sampler. The deposited particles were investigated using electron microscopy techniques in combination with image processing software. This approach enables the chemical and morphological characterization as well as quantification of released nanoparticles from a spray product. The differentiation of solid ENP from the released nano-sized droplets was achieved by applying a thermo-desorbing unit. After optimization, the setup was applied to investigate different spray situations using both pump and gas propellant spray dispensers for a commercially available water-based nano-silver spray. The pump spray situation showed no measurable nanoparticle release, whereas in the case of the gas spray, a significant release was observed. From the results it can be assumed that the homogeneously distributed ENP from the original dispersion grow in size and change morphology during and after the spray process but still exist as nanometer particles of size <100 nm. Furthermore, it seems that the release of ENP correlates with the generated aerosol droplet size distribution produced by the spray vessel type used. This is the first study presenting results concerning the release of ENP from spray products.

  13. Membrane Assisted Enzyme Fractionation

    DEFF Research Database (Denmark)

    Yuan, Linfeng

    to the variation in size of the proteins and a reasonable separation factor can be observed only when the size difference is in the order of 10 or more. This is partly caused by concentration polarization and membrane fouling which hinders an effective separation of the proteins. Application of an electric field...... across the porous membrane has been demonstrated to be an effective way to reduce concentration polarization and membrane fouling. In addition, this technique can also be used to separate the proteins based on difference in charge, which to some extent overcome the limitations of size difference...... of proteins on the basis of their charge, degree of hydrophobicity, affinity or size. Adequate purity is often not achieved unless several purification steps are combined thereby increasing cost and reducing product yield. Conventional fractionation of proteins using ultrafiltration membranes is limited...

  14. Turbulent Concentration of MM-Size Particles in the Protoplanetary Nebula: Scaled-Dependent Multiplier Functions

    Science.gov (United States)

    Cuzzi, Jeffrey N.; Hartlep, Thomas; Weston, B.; Estremera, Shariff Kareem

    2014-01-01

    The initial accretion of primitive bodies (asteroids and TNOs) from freely-floating nebula particles remains problematic. Here we focus on the asteroids where constituent particle (read "chondrule") sizes are observationally known; similar arguments will hold for TNOs, but the constituent particles in those regions will be smaller, or will be fluffy aggregates, and are unobserved. Traditional growth-bysticking models encounter a formidable "meter-size barrier" [1] (or even a mm-cm-size barrier [2]) in turbulent nebulae, while nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids [3]. Even if growth by sticking could somehow breach the meter size barrier, other obstacles are encountered through the 1-10km size range [4]. Another clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids [5]; scenarios leading directly from independent nebula particulates to this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios [6-8]. The leapfrog scenario we have studied in detail involves formation of dense clumps of aerodynamically selected, typically mm-size particles in turbulence, which can under certain conditions shrink inexorably on 100-1000 orbit timescales and form 10-100km diameter sandpile planetesimals. The typical sizes of planetesimals and the rate of their formation [7,8] are determined by a statistical model with properties inferred from large numerical simulations of turbulence [9]. Nebula turbulence can be described by its Reynolds number Re = L/eta sup(4/3), where L = ETA alpha sup (1/2) the largest eddy scale, H is the nebula gas vertical scale height, and a the nebula turbulent viscosity parameter, and ? is the Kolmogorov or smallest scale in turbulence (typically about 1km), with eddy turnover time t?. In the nebula, Re is far larger than any numerical simulation can

  15. Highly Localized Acoustic Streaming and Size-Selective Submicrometer Particle Concentration Using High Frequency Microscale Focused Acoustic Fields.

    Science.gov (United States)

    Collins, David J; Ma, Zhichao; Ai, Ye

    2016-05-17

    Concentration and separation of particles and biological specimens are fundamental functions of micro/nanofluidic systems. Acoustic streaming is an effective and biocompatible way to create rapid microscale fluid motion and induce particle capture, though the >100 MHz frequencies required to directly generate acoustic body forces on the microscale have traditionally been difficult to generate and localize in a way that is amenable to efficient generation of streaming. Moreover, acoustic, hydrodynamic, and electrical forces as typically applied have difficulty manipulating specimens in the submicrometer regime. In this work, we introduce highly focused traveling surface acoustic waves (SAW) at high frequencies between 193 and 636 MHz for efficient and highly localized production of acoustic streaming vortices on microfluidic length scales. Concentration occurs via a novel mechanism, whereby the combined acoustic radiation and streaming field results in size-selective aggregation in fluid streamlines in the vicinity of a high-amplitude acoustic beam, as opposed to previous acoustic radiation induced particle concentration where objects typically migrate toward minimum pressure locations. Though the acoustic streaming is induced by a traveling wave, we are able to manipulate particles an order of magnitude smaller than possible using the traveling wave force alone. We experimentally and theoretically examine the range of particle sizes that can be captured in fluid streamlines using this technique, with rapid particle concentration demonstrated down to 300 nm diameters. We also demonstrate that locations of trapping and concentration are size-dependent, which is attributed to the combined effects of the acoustic streaming and acoustic forces.

  16. Detection of infarct size safety threshold for left ventricular ejection fraction impairment in acute myocardial infarction successfully treated with primary percutaneous coronary intervention.

    Science.gov (United States)

    Sciagrà, Roberto; Cipollini, Fabrizio; Berti, Valentina; Migliorini, Angela; Antoniucci, David; Pupi, Alberto

    2013-04-01

    In acute myocardial infarction (AMI) treated by primary percutaneous coronary intervention (PCI), there is a direct relationship between myocardial damage and consequent left ventricular (LV) functional impairment. It is however unclear whether there is a safety threshold below which infarct size does not significantly affect LV ejection fraction (EF). The aim of this study was to evaluate the relationship between infarct size and LVEF in AMI patients treated by successful PCI using a specific statistical approach to identify a possible safety threshold. Among patients with recent AMI submitted to perfusion gated single photon emission computed tomography (SPECT) to define the infarct size, the data of 427 subjects with sizable infarct size were considered. The relationship between infarct size and LVEF was analysed using a simple segmented regression (SSR) model and an iterative algorithm based on robust least squares (RLS) for parameter estimation. The RLS algorithm detected two break points in the SSR model, set at infarct size values of 11.0 and 51.5 %. Because the slope coefficients of the two extreme segments of the regression line were not significant, by constraining such segments to zero slope in the SSR model, the lower break point was identified at infarct size = 8 % and the upper one at 45 %. Using a rigorous statistical approach, it is possible to demonstrate that below a threshold of 8 % the infarct size apparently does not affect the LVEF and therefore a safety threshold could be set at this value. Furthermore, the same analysis suggests that the relationship between infarct size and LVEF impairment is lost for an infarct size > 45 %.

  17. Physicochemical characterization of Capstone depleted uranium aerosols I: uranium concentration in aerosols as a function of time and particle size.

    Science.gov (United States)

    Parkhurst, Mary Ann; Cheng, Yung Sung; Kenoyer, Judson L; Traub, Richard J

    2009-03-01

    During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing DU were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time, particularly within the first minute after a shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s after perforation, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% after 30 min. The initial and maximum uranium concentrations were lower in the Bradley vehicle than those observed in the Abrams tank, and the concentration levels decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in a cyclone sampler, which collected aerosol continuously for 2 h after perforation. The percentages of uranium mass in the cyclone separator stages ranged from 38 to 72% for the Abrams tank with conventional armor. In most cases, it varied with particle size, typically with less uranium associated with the smaller particle sizes. Neither the Abrams tank with DU armor nor the Bradley vehicle results were specifically correlated with particle size and can best be represented by their average uranium mass concentrations of 65

  18. A Field Study on the Respiratory Deposition of the Nano-Sized Fraction of Mild and Stainless Steel Welding Fume Metals.

    Science.gov (United States)

    Cena, L G; Chisholm, W P; Keane, M J; Chen, B T

    2015-01-01

    A field study was conducted to estimate the amount of Cr, Mn, and Ni deposited in the respiratory system of 44 welders in two facilities. Each worker wore a nanoparticle respiratory deposition (NRD) sampler during gas metal arc welding (GMAW) of mild and stainless steel and flux-cored arc welding (FCAW) of mild steel. Several welders also wore side-by-side NRD samplers and closed-face filter cassettes for total particulate samples. The NRD sampler estimates the aerosol's nano-fraction deposited in the respiratory system. Mn concentrations for both welding processes ranged 2.8-199 μg/m3; Ni concentrations ranged 10-51 μg/m3; and Cr concentrations ranged 40-105 μg/m3. Cr(VI) concentrations ranged between 0.5-1.3 μg/m3. For the FCAW process the largest concentrations were reported for welders working in pairs. As a consequence this often resulted in workers being exposed to their own welding fumes and to those generated from the welding partner. Overall no correlation was found between air velocity and exposure (R2 = 0.002). The estimated percentage of the nano-fraction of Mn deposited in a mild-steel-welder's respiratory system ranged between 10 and 56%. For stainless steel welding, the NRD samplers collected 59% of the total Mn, 90% of the total Cr, and 64% of the total Ni. These results indicate that most of the Cr and more than half of the Ni and Mn in the fumes were in the fraction smaller than 300 nm.

  19. PLASMA STEROID CONCENTRATIONS IN RELATION TO SIZE AND AGE IN JUVENILE ALLIGATORS FROM TWO FLORIDA LAKES.

    Science.gov (United States)

    Previous studies have reported a number of physiological differences among juvenile alligators from two well-studied populations (Lake Apopka and Lake Woodruff) in north central Florida. These studies obtained alligators of similar size from each lake under the assumption that th...

  20. From nanoparticles to large aerosols: Ultrafast measurement methods for size and concentration

    International Nuclear Information System (INIS)

    Keck, Lothar; Spielvogel, Juergen; Grimm, Hans

    2009-01-01

    A major challenge in aerosol technology is the fast measurement of number size distributions with good accuracy and size resolution. The dedicated instruments are frequently based on particle charging and electric detection. Established fast systems, however, still feature a number of shortcomings. We have developed a new instrument that constitutes of a high flow Differential Mobility Analyser (high flow DMA) and a high sensitivity Faraday Cup Electrometer (FCE). The system enables variable flow rates of up to 150 lpm, and the scan time for size distribution can be shortened considerably due to the short residence time of the particles in the DMA. Three different electrodes can be employed in order to cover a large size range. First test results demonstrate that the scan time can be reduced to less than 1 s for small particles, and that the results from the fast scans feature no significant difference to the results from established slow method. The fields of application for the new instrument comprise the precise monitoring of fast processes with nanoparticles, including monitoring of engine exhaust in automotive research.

  1. From nanoparticles to large aerosols: Ultrafast measurement methods for size and concentration

    Science.gov (United States)

    Keck, Lothar; Spielvogel, Jürgen; Grimm, Hans

    2009-05-01

    A major challenge in aerosol technology is the fast measurement of number size distributions with good accuracy and size resolution. The dedicated instruments are frequently based on particle charging and electric detection. Established fast systems, however, still feature a number of shortcomings. We have developed a new instrument that constitutes of a high flow Differential Mobility Analyser (high flow DMA) and a high sensitivity Faraday Cup Electrometer (FCE). The system enables variable flow rates of up to 150 lpm, and the scan time for size distribution can be shortened considerably due to the short residence time of the particles in the DMA. Three different electrodes can be employed in order to cover a large size range. First test results demonstrate that the scan time can be reduced to less than 1 s for small particles, and that the results from the fast scans feature no significant difference to the results from established slow method. The fields of application for the new instrument comprise the precise monitoring of fast processes with nanoparticles, including monitoring of engine exhaust in automotive research.

  2. Concentration and size dependence of peak wavelength shift on quantum dots in colloidal suspension

    Science.gov (United States)

    Rinehart, Benjamin S.; Cao, Caroline G. L.

    2016-08-01

    Quantum dots (QDs) are semiconductor nanocrystals that have significant advantages over organic fluorophores, including their extremely narrow Gaussian emission bands and broad absorption bands. Thus, QDs have a wide range of potential applications, such as in quantum computing, photovoltaic cells, biological sensing, and electronics. For these applications, aliasing provides a detrimental effect on signal identification efficiency. This can be avoided through characterization of the QD fluorescence signals. Characterization of the emissivity of CdTe QDs as a function of concentration (1 to 10 mg/ml aqueous) was conducted on 12 commercially available CdTe QDs (emission peaks 550 to 730 nm). The samples were excited by a 50-mW 405-nm laser with emission collected via a free-space CCD spectrometer. All QDs showed a redshift effect as concentration increased. On average, the CdTe QDs exhibited a maximum shift of +35.6 nm at 10 mg/ml and a minimum shift of +27.24 nm at 1 mg/ml, indicating a concentration dependence for shift magnitude. The concentration-dependent redshift function can be used to predict emission response as QD concentration is changed in a complex system.

  3. Optimizing concentration of shifter additive for plastic scintillators of different size

    Energy Technology Data Exchange (ETDEWEB)

    Adadurov, A.F. [Institute for Scintillating materials, NPC Institute for Single Crystals, NAN of Ukraine, Lenin Avenue 61, 61001 Kharkov (Ukraine)], E-mail: adadurov@isma.kharkov.ua; Zhmurin, P.N.; Lebedev, V.N.; Titskaya, V.D. [Institute for Scintillating materials, NPC Institute for Single Crystals, NAN of Ukraine, Lenin Avenue 61, 61001 Kharkov (Ukraine)

    2009-02-11

    This paper concerns the influence of wavelength shifting (secondary) luminescent additive (LA{sub 2}) on the light yield of polystyrene-based plastic scintillator (PS) taking self-absorption into account. Calculations of light yield dependence on concentration of 1.4-bis(2-(5-phenyloxazolyl)-benzene (POPOP) as LA{sub 2} were made for various path lengths of photons in PS. It is shown that there is an optimal POPOP concentration (C{sub opt}), which provides a maximum light yield for a given path length. This optimal concentration is determined by the competition of luminescence and self-reflection processes. C{sub opt} values were calculated for PS of different dimensions. For small PS, C{sub opt}{approx}0.02%, which agree with a common (standard) value of POPOP concentration. For higher PS dimensions, the optimal POPOP concentration is decreased (to C{sub opt}{approx}0.006% for 320x30x2 cm sample), reducing the light yield from PS by almost 35%.

  4. Different relationships between personal exposure and ambient concentration by particle size.

    Science.gov (United States)

    Guak, Sooyoung; Lee, Kiyoung

    2018-04-06

    Ambient particulate matter (PM) concentrations at monitoring stations were often used as an indicator of population exposure to PM in epidemiological studies. The correlation between personal exposure and ambient concentrations of PM varied because of diverse time-activity patterns. The aim of this study was to determine the relationship between personal exposure and ambient concentrations of PM 10 and PM 2.5 with minimal impact of time-activity pattern on personal exposure. Performance of the MicroPEM, v3.2 was evaluated by collocation with central ambient air monitors for PM 10 and PM 2.5 . A field technician repeatedly conducted measurement of 24 h personal exposures to PM 10 and PM 2.5 with a fixed time-activity pattern of office worker over 26 days in Seoul, Korea. The relationship between the MicroPEM and the ambient air monitor showed good linearity. Personal exposure and ambient concentrations of PM 2.5 were highly correlated with a fixed time-activity pattern compared with PM 10 . The finding implied a high infiltration rate of PM 2.5 and low infiltration rate of PM 10 . The relationship between personal exposure and ambient concentrations of PM 10 and PM 2.5 was different for high level episodes. In the Asian dust episode, staying indoors could reduce personal exposure to PM 10 . However, personal exposure to PM 2.5 could not be reduced by staying indoors during the fine dust advisory episode.

  5. Effect of Photon Beam Energy, Gold Nanoparticle Size and Concentration on the Dose Enhancement in Radiation Therapy

    Directory of Open Access Journals (Sweden)

    Nahideh Gharehaghaji

    2013-02-01

    Full Text Available Introduction: Gold nanoparticles have been used as radiation dose enhancing materials in recent investigations. In the current study, dose enhancement effect of gold nanoparticles on tumor cells was evaluated using Monte Carlo (MC simulation. Methods: We used MCNPX code for MC modeling in the current study. A water phantom and a tumor region with a size of 1×1×1 cm3 loaded with gold nanoparticles were simulated. The macroscopic dose enhancement factor was calculated for gold nanoparticles with sizes of 30, 50, and 100 nm. Also, we simulated different photon beams including mono-energetic beams (50-120 keV, a Cobalt-60 beam, 6 & 18 MV photon beams of a conventional linear accelerator. Results: We found a dose enhancement factor (DEF of from 1.4 to 3.7 for monoenergetic kilovoltage beams, while the DEFs for megavoltage beams were negligible and less than 3% for all GNP sizes and concentrations. The optimum energy for higher DEF was found to be the 90 keV monoenergetic beam. The effect of GNP size was not considerable, but the GNP concentration had a substantial impact on achieved DEF in GNP-based radiation therapy. Conclusion: The results were in close agreement with some previous studies considering the effect of photon energy and GNP concentration on observed DEF. Application of GNP-based radiation therapy using kilovoltage beams is recommended.

  6. Size and Concentration Analysis of Gold Nanoparticles With Ultraviolet-Visible Spectroscopy

    Directory of Open Access Journals (Sweden)

    Sanim Rahman

    2016-10-01

    Full Text Available Spherical gold nanoparticles (GNPs are synthesized by Turkevich Method and PEL 35 UV-VIS spectrophotometer recorded the wavelength and absorption of the Surface Plasmon Resonance (SPR peak. The diameter and concentration of solute GNPs are calculated. The concentration of GNPs is done with Beer’s law. The average diameter of GNPs is done via the ratio of SPR peak to the absorbance at 450 nm. The diameters are compared to SEM scan of synthesized GNPs and Sigma-Aldrich values.

  7. Monitoring of DSP toxins in small-sized plankton fraction of seawater collected in Mutsu Bay, Japan, by ELISA method: relation with toxin contamination of scallop.

    Science.gov (United States)

    Imai, Ichiro; Sugioka, Hikaru; Nishitani, Goh; Mitsuya, Tadashi; Hamano, Yonekazu

    2003-01-01

    Monitorings were conducted on DSP toxins in mid-gut gland of scallop (mouse assay), cell numbers of toxic dinoflagellate species of Dinophysis, and diarrhetic shellfish poisoning (DSP) toxins in small-sized (0.7-5 microm) plankton fraction of seawater collected from surface (0 m) and 20 m depth at a station in Mutsu Bay, Aomori Prefecture, Japan, in 2000. A specific enzyme-linked immunosorbent assay (ELISA) was employed for the analysis of DSP toxins in small-sized plankton fraction using a mouse monoclonal anti-okadaic acid antibody which recognizes okadaic acid, dinophysistoxin-1, and dinophysistoxin-3. DSP toxins were detected twice in the mid-gut gland of scallops at 1.1-2.3 MU (mouse units) g(-1) on 26 June and at 0.6-1.2 MU g(-1) on 3 July, respectively. Relatively high cell densities of D. fortii were observed on 26 June and 11 September, and may only contribute to the bivalve toxicity during late June to early July. D. acuminata did not appear to be responsible for the toxicity of scallops in Mutsu Bay in 2000. ELISA monitoring of small-sized plankton fraction in seawater could detect DSP toxins two weeks before the detection of the toxin in scallops, and could do so two weeks after the loss of the bivalve toxicity by mouse assay. On 17 July, toxic D. fortii was detected at only small number, <10 cells l(-1), but DSP toxins were detected by the ELISA assay, suggesting a presence of other toxic small-sized plankton in seawater. For the purpose of reducing negative impacts of DSP occurrences, monitorings have been carried out hitherto on DSP toxins of bivalve tissues by mouse assay and on cell densities of "toxic" species of Dinophysis. Here we propose a usefulness of ELISA monitoring of plankton toxicity, especially in small-sized fraction, which are possible foods of mixotrophic Dinophysis, as a practical tool for detecting and predicting DSPs in coastal areas of fisheries grounds of bivalve aquaculture.

  8. Concentrations and size distribution of inhalable and respirable dust among sugar industry workers: a pilot study in Khon Kaen, Thailand.

    Science.gov (United States)

    Sakunkoo, Pornpun; Chaiear, Naesinee; Chaikittiporn, Chalermchai; Sadhra, Steven

    2011-11-01

    There has been very limited information regarding bagasse exposure among workers in sugar industries as well as on health outcomes. The authors determined the occupational exposure of sugar industry workers in Khon Kaen to airborne bagasse dust. The size of the bagasse dust ranged from 0.08 to 9 µm with the highest size concentration of 2.1 to 4.7 µm. The most common size had a geometric mean diameter of 5.2 µm, with a mass concentration of 6.89 mg/m(3)/log µm. The highest mean values of inhalable and respirable dust were found to be 9.29 mg/m(3) from February to April in bagasse storage, 5.12 mg/m(3) from May to September, and 4.12 mg/m(3) from October to January. Inhalable dust concentrations were 0.33, 0.47, and 0.41 mg/m(3), respectively. Workers are likely to be exposed to high concentrations of bagasse dust and are at risk of respiratory diseases. Preventive measures, both in the form of engineering designs and personal protective devices, should be implemented.

  9. Atmospheric particulate matter size distribution and concentration in West Virginia coal mining and non-mining areas.

    Science.gov (United States)

    Kurth, Laura M; McCawley, Michael; Hendryx, Michael; Lusk, Stephanie

    2014-07-01

    People who live in Appalachian areas where coal mining is prominent have increased health problems compared with people in non-mining areas of Appalachia. Coal mines and related mining activities result in the production of atmospheric particulate matter (PM) that is associated with human health effects. There is a gap in research regarding particle size concentration and distribution to determine respiratory dose around coal mining and non-mining areas. Mass- and number-based size distributions were determined with an Aerodynamic Particle Size and Scanning Mobility Particle Sizer to calculate lung deposition around mining and non-mining areas of West Virginia. Particle number concentrations and deposited lung dose were significantly greater around mining areas compared with non-mining areas, demonstrating elevated risks to humans. The greater dose was correlated with elevated disease rates in the West Virginia mining areas. Number concentrations in the mining areas were comparable to a previously documented urban area where number concentration was associated with respiratory and cardiovascular disease.

  10. Design and performance of large-pixel-size high-fill-fraction TES arrays for future X-ray astrophysics missions

    International Nuclear Information System (INIS)

    Figueroa-Feliciano, E.; Bandler, S.R.; Chervenak, J.; Finkbeiner, F.; Iyomoto, N.; Kelley, R.L.; Kilbourne, C.A.; Porter, F.S.; Saab, T.; Sadleir, J.; White, J.

    2006-01-01

    We have designed, modeled, fabricated and tested a 600μm high-fill-fraction microcalorimeter array that will be a good match to the requirements of future X-ray missions. Our devices use transition-edge sensors coupled to overhanging bismuth/copper absorbers to produce arrays with 97% or higher fill fraction. An extensive modeling effort was undertaken in order to accommodate large pixel sizes (500-1000μm) and maintain the best energy resolution possible. The finite thermalization time of the large absorber and the associated position dependence of the pulse shape on absorption position constrain the time constants of the system given a desired energy-resolution performance. We show the results of our analysis and our new pixel design, consisting of a novel TES-on-the-side architecture which creates a controllable TES-absorber conductance

  11. Pyrogenic organic matter accumulation after density and particle size fractionation of burnt Cambisol using solid-state nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    López-Martín, María; Knicker, Heike

    2017-04-01

    Fires lead to formation of the pyrogenic organic matter (PyOM) which is quickly incorporated into the soil. The charring process involves chemical alterations of the litter material, where biologically available structures are transferred into aromatic polymers, such as black carbon (BC) and black nitrogen (BN). In order to reveal the medium term fate of BC and BN in soils, the top 5 cm of A horizons from unburnt, single and double burnt Cambisols of the Sierra de Aznalcóllar (Southern Spain) were collected 7 year after an intense fire and separated according to their density and their size (Golchin et al., 1994; Sohi et al., 2001). The density fractionation yielded in the free (fPOM), occluded particulate organic matter (oPOM) and the mineral-association organic fraction (MAF) and was performed using a sodium polytungstate solution with a density of 1.8 g cm-3. The MAF was further separated into the sand (2 mm to 63 μm) and coarse silt (63 to 20 μm) and fine fraction (solid-state 13C and 15N NMR spectroscopy. The 13C and 15N NMR spectra of all fPOM and oPOM fractions are dominated by signals assignable to O-alkyl C followed by resonance lines of alkyl C. The spectra indicate that fPOM is mainly composed of undecomposed plant debris whereas oPOM is rich in unsubstituted-aliphatic material. The lack of intensity in the chemical shift region from 160 to140 ppm in the spectra of the small size fractions reveals the absence of lignin residues. This, their low C/N ratios and the clear 13C-signal attributed to carboxylic C allows the conclusion that this fraction mainly composed of microbial residues. Former studies evidenced that aromaticity of the burnt bulk soil decreased with elapsing time after the fire. The present investigation revealed that most of the remaining aromatic C accumulated in the POM fractions, which is in contrast to other studies showing a preferential recovery of BC in the fine particle size fractions. Possibly, the poor interaction between Py

  12. Examination of a high resolution laser optical plankton counter and FlowCAM for measuring plankton concentration and size

    Science.gov (United States)

    Kydd, Jocelyn; Rajakaruna, Harshana; Briski, Elizabeta; Bailey, Sarah

    2018-03-01

    Many commercial ships will soon begin to use treatment systems to manage their ballast water and reduce the global transfer of harmful aquatic organisms and pathogens in accordance with upcoming International Maritime Organization regulations. As a result, rapid and accurate automated methods will be needed to monitoring compliance of ships' ballast water. We examined two automated particle counters for monitoring organisms ≥ 50 μm in minimum dimension: a High Resolution Laser Optical Plankton Counter (HR-LOPC), and a Flow Cytometer with digital imaging Microscope (FlowCAM), in comparison to traditional (manual) microscopy considering plankton concentration, size frequency distributions and particle size measurements. The automated tools tended to underestimate particle concentration compared to standard microscopy, but gave similar results in terms of relative abundance of individual taxa. For most taxa, particle size measurements generated by FlowCAM ABD (Area Based Diameter) were more similar to microscope measurements than were those by FlowCAM ESD (Equivalent Spherical Diameter), though there was a mismatch in size estimates for some organisms between the FlowCAM ABD and microscope due to orientation and complex morphology. When a single problematic taxon is very abundant, the resulting size frequency distribution curves can become skewed, as was observed with Asterionella in this study. In particular, special consideration is needed when utilizing automated tools to analyse samples containing colonial species. Re-analysis of the size frequency distributions with the removal of Asterionella from FlowCAM and microscope data resulted in more similar curves across methods with FlowCAM ABD having the best fit compared to the microscope, although microscope concentration estimates were still significantly higher than estimates from the other methods. The results of our study indicate that both automated tools can generate frequency distributions of particles

  13. Time and concentration dependency in the potentially affected fraction of species: the case of hydrogen peroxide treatment of ballast water

    NARCIS (Netherlands)

    Smit, M.G.D.; Ebbens, E.; Jak, R.G.; Huijbregts, M.J.A.

    2008-01-01

    Transport of large volumes of ballast water contributes greatly to invasions of species. Hydrogen peroxide (H2O2) can be used as a disinfectant to prevent the spread of exotic species via ballast water. Instead of using environmental risk assessment techniques for protecting a certain fraction of

  14. Benzene and toluene concentrations in a hemodialysis room in a medium sized South Korean city.

    Science.gov (United States)

    Kang, Moon-Soo; Hong, Joong-Rock; Gil, Hyo-Wook; Yang, Jong-Oh; Lee, Eun-Young; Hong, Sae-Yong; Jun, Yong-Taek; Son, Bu-Soon

    2008-09-01

    The current study was designed to determine whether the indoor air pollution in a hemodialysis room (HD) was different from that of other comparable areas in a hospital. Five air monitor samplers were hung on the ceiling and placed on the table in both the HD and general ward nursing stations, respectively. In addition, five samplers were placed in the nurse's breathing zone of the HD and the general ward, respectively. Ten air monitor samplers were also placed on the edge of the bed in the HD, which represented the patient's breathing zone. The levels of benzene and toluene were analyzed by GC/MS. In the general ward, the toluene concentration was significantly higher in the nurse breathing zone than that for the ceiling or table samples (p=0.001). The benzene concentration was also significantly higher in the general ward nurse breathing zone than that in the HD (p=0.006). In addition, the benzene concentrations on the table were higher at the general ward as compared to the HD (p=0.028), but there was no significant difference between the ceiling, general ward station and HD. Both the benzene and toluene concentrations in the HD appear to be more affected by the outdoor atmospheric conditions than by any potential indoor internal sources.

  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

    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. Influence of milk urea concentration on fractional urea disappearance rate from milk to blood plasma in dairy cows.

    Science.gov (United States)

    Spek, J W; Dijkstra, J; Bannink, A

    2016-05-01

    The relationship between milk urea nitrogen (MUN; mg of N/dL) and urinary N excretion is affected, among others, by diurnal dynamics in MUN, which in turn is largely influenced by feed intake pattern and characteristics of urea transfer from blood plasma to milk and vice versa. This study aimed to obtain insight in urea transfer characteristics within the mammary gland and from the mammary gland to blood plasma in dairy cows at various concentrations of plasma urea nitrogen (PUN; mg of N/dL) and MUN. Urea transfer from milk to blood plasma and urea transfer within the mammary gland itself was evaluated in a 4×4 Latin square design using 4 lactating multiparous Holstein-Friesian cows (milk production of 39.8±4.70kg/d and 90±3.9 d in milk). Treatments consisted of 4 primed continuous intravenous urea infusions of 0, 5, 10, and 15g of urea/h. Boluses of [(15)N(15)N]urea were injected in cistern milk at 20, 60, and 100 min before the 1700h milking. Milk was collected in portions of approximately 2 L at the 1700h milking. Milk samples were analyzed for urea and enrichment of (15)N-urea. Results from one cow were discarded because of leakage of milk from the teats after injection of boluses of [(15)N(15)N]urea. Increasing urea infusion rate linearly increased PUN from 11.4 (0g of urea/h) to 25.9mg/dL (15g of urea/h) and MUN from 10.3 (0g of urea/h) to 23.5 (15g of urea/h) mg of N/dL. The percentage of injected [(15)N(15)N]urea recovered from milk at the time of injection was not affected by urea infusion rate and varied between 65.1 and 73.0%, indicating that a substantial portion of injected [(15)N(15)N]urea was not accounted for by collected milk. The estimated fractional disappearance rate of (15)N-urea from milk to blood (Kurea; per hour) linearly increased from 0.429 (0g of urea/h) to 0.641 per hour (15g of urea/h). Cistern injected [(15)N(15)N]urea diffused within 20 min after injection toward alveoli milk. Calculations with the average Kurea estimated in this

  17. Carbon and Nitrogen Mineralization in Relation to Soil Particle-Size Fractions after 32 Years of Chemical and Manure Application in a Continuous Maize Cropping System

    Science.gov (United States)

    Shao, Xingfang; Zhu, Ping; Zhang, Wenju; Xu, Minggang; Murphy, Daniel V.

    2016-01-01

    Long-term manure application is recognized as an efficient management practice to enhance soil organic carbon (SOC) accumulation and nitrogen (N) mineralization capacity. A field study was established in 1979 to understand the impact of long-term manure and/or chemical fertilizer application on soil fertility in a continuous maize cropping system. Soil samples were collected from field plots in 2012 from 9 fertilization treatments (M0CK, M0N, M0NPK, M30CK, M30N, M30NPK, M60CK, M60N, and M60NPK) where M0, M30, and M60 refer to manure applied at rates of 0, 30, and 60 t ha−1 yr−1, respectively; CK indicates no fertilizer; N and NPK refer to chemical fertilizer in the forms of either N or N plus phosphorus (P) and potassium (K). Soils were separated into three particle-size fractions (2000–250, 250–53, and fertilization application, on the accumulation and mineralization of SOC and total N in each fraction. Results showed that long-term manure application significantly increased SOC and total N content and enhanced C and N mineralization in the three particle-size fractions. The content of SOC and total N followed the order 2000–250 μm > 250–53μm > 53 μm fraction, whereas the amount of C and N mineralization followed the reverse order. In the fertilizers, resulted in increased soil microbial biomass C and N, and a decreased microbial metabolic quotient. Consequently, long-term manure fertilization was beneficial to both soil C and N turnover and microbial activity, and had significant effect on the microbial metabolic quotient. PMID:27031697

  18. The effect of concentration of glycerol and electric current on the morphology and particle size of electrodeposited cadmium powder

    Directory of Open Access Journals (Sweden)

    S. G. Viswanath

    2013-06-01

    Full Text Available Cadmium powder was obtained by electrodeposition of cadmium from glycerol and sulphuric acid. The morphology and particle size of these powders were studied. Broken dendrites, intermingled with spongy and irregular particles were observed in the powder. Around 60% of particles were below 100 µm. XRD studies showed that particles with sizes between 212.2 and 303.2 nm were present in the powder. The apparent density of cadmium powder decreased with increase in concentration of glycerol. The stability of the powder and current efficiency were also studied

  19. [Effect of Long-term Fertilizer Application on the Stability of Organic Carbon in Particle Size Fractions of a Paddy Soil in Zhejiang Province, China].

    Science.gov (United States)

    Mao, Xia-li; Lu, Kou-ping; Sun, Tao; Zhang, Xiao-kai; He, Li-zhi; Wang, Hai-long

    2015-05-01

    Effects of chemical fertilizers and organic manure on the soil organic carbon (SOC) content in particle size fractions of paddy soil were investigated in a 17-year long-term fertilization field experiment in Zhejiang Province, China. The inherent chemical composition of silt- and clay-associated SOC was evaluated with solid-state 13C-NMR spectroscopy. Compared to CK (no fertilizer treatment), NPKRS (NPK fertilizers plus rice straw) , NPKOM (NPK fertilizers plus organic manure) , NPK (NPK fertilizers) and OM (organic manure alone) treatments significantly (P fertilizers alone, combined application of organic amendments and NPK fertilizers facilitated the storage of newly sequestered SOC in silt- and clay-sized fractions, which could be more conducive to the stability of SOC. Based on 13C-NMR spectra, both silt and clay fractions were composed of Alkyl-C, O-alkyl-C, Aromatic-C and carbonyl-C. Changes in the relative proportion of different C species were observed between silt and clay fractions: the clay fraction had relatively more Alkyl-C, carbonyl-C and less O-alkyl-C, Aromatic-C than those in the silt fraction. This might be ascribed to the fact that the organic matter complexed with clay was dominated by microbial products, whereas the silt appeared to be rich in aromatic residues derived from plants. The spectra also showed that the relative proportion of different C species was modified by fertilization practices. In comparison with organic amendments alone, the relative proportion of Alkyl-C was decreased by 9.1%-11.9% and 13.7%-19.9% under combined application of organic amendments and chemical fertilizers, for silt and clay, respectively, and that of O-alkyl-C was increased by 2.9%-6.3% and 13.4%-22.1%, respectively. These results indicated that NPKOM and NPKRS treatments reduced the decomposition rate of SOC. The aromaticity, hydrophobicity and, hence, chemical recalcitrance of silt- and clay-associated SOC in the NPK fertilizer treatments were lower than

  20. Pyrolysis compound specific isotopic analysis (δ13C and δD Py-CSIA) of soil organic matter size fractions under four vegetation covers.

    Science.gov (United States)

    Jiménez-Morillo, Nicasio T.; González-Vila, Francisco J.; Almendros, Gonzalo; De la Rosa, José M.; González-Pérez, José A.

    2015-04-01

    A chemical characterization of soil organic matter (SOM) under different ground cover from a Mediterranean climate (Doñana National Park, Andalusia, Spain) is approached using bulk δ15N, δ13C, δ18O and δD isotopic analysis (C/TC-IRMS) and δ13C and δD pyrolysis compound specific isotopic analysis (Py-CSIA: Py-GC-C/TC-IRMS). Soil samples were collected in sandy soils, Arenosols (WRB 2006) from the Doñana National Park (SW Spain) under different vegetation cover: cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Two size fractions; coarse (C: 1-2 mm) and fine (F: studied from each soil. A complete conventional analytical pyrolysis (Py-GC/MS) of these samples have been studied in detail (Jiménez-Morillo et al., 2015). Bulk isotopic analysis of stable light elements (δ15N, δ13C, δ18O and δD) revealed particular isotopic signatures showing differences related with the main vegetation cover and the different soil size fraction. All samples had a carbon isotopic signature between -26 and -29 ‰, which indicated that the organic matter in the two fractions of each soil sample derived from C3-type plants. The bulk δD isotopic signature in whole soil sample indicate a lower deuterium fractionation occurs in SOM under arboreal than under no-arboreal vegetation, this can be caused by the occurrence of a higher water evaporation rate under bush vegetation and/or to differences due to leaf morphology as previously described (Leaney et al., 1985). A δ15N vs. δ18O chart may provide some clues about N origin in the soil and particularly about the original source of nitrates (Kendall et al., 1996). In in all sample and size fractions our values are in the chart area corresponding to NO3 in precipitation, with lighter δ18O (c. 20 ‰) values compatible with fertilizers may be from adjacent crops. In addition we were able to assign δ13C and δD values for a number of specific SOM

  1. Effects of locust bean gum and mono- and diglyceride concentrations on particle size and melting rates of ice cream.

    Science.gov (United States)

    Cropper, S L; Kocaoglu-Vurma, N A; Tharp, B W; Harper, W J

    2013-06-01

    The objective of this study was to determine how varying concentrations of the stabilizer, locust bean gum (LBG), and different levels of the emulsifier, mono- and diglycerides (MDGs), influenced fat aggregation and melting characteristics of ice cream. Ice creams were made containing MDGs and LBG singly and in combination at concentrations ranging between 0.0% to 0.14% and 0.0% to 0.23%, respectively. Particle size analysis, conducted on both the mixes and ice cream, and melting rate testing on the ice cream were used to determine fat aggregation. No significant differences (P ice cream mixes. However, higher concentrations of both LBG and MDG in the ice creams resulted in values that were larger than the control. This study also found an increase in the particle size values when MDG levels were held constant and LBG amounts were increased in the ice cream. Ice creams with higher concentrations of MDG and LBG together had the greatest difference in the rate of melting than the control. The melting rate decreased with increasing LBG concentrations at constant MDG levels. These results illustrated that fat aggregation may not only be affected by emulsifiers, but that stabilizers may play a role in contributing to the destabilization of fat globules. © 2013 Institute of Food Technologists®

  2. Major- and trace elements in grain size fractions of the Apollo-17 core of the drilled sample 74001

    International Nuclear Information System (INIS)

    Kraehenbuehl, U.; Gunten, H.R. von; Jost, D.; Meyer, G.; Wegmueller, F.

    1980-01-01

    Two layers of a drill sample were examined, one from a depth of 38 cm and the other from 58 cm depth. Neutron activation analysis was used for one group of elements, and radiochemical analysis for another. Over a range of grain size from 36 to 450 μm, the trace elements U, Co, and La were found to uniformly distributed, as was iron. The top layer consistently showed a 5-8% higher content. The volatile trace elements Ge and Cd were found to be enriched in the smaller grain sizes. This contradicts previous assumptions of an enrichment of the more volatile elements in top layers owing to more rapid cooling of volcanic eruptions. (R.S.)

  3. Long-term cloud condensation nuclei number concentration, particle number size distribution and chemical composition measurements at regionally representative observatories

    Science.gov (United States)

    Schmale, Julia; Henning, Silvia; Decesari, Stefano; Henzing, Bas; Keskinen, Helmi; Sellegri, Karine; Ovadnevaite, Jurgita; Pöhlker, Mira L.; Brito, Joel; Bougiatioti, Aikaterini; Kristensson, Adam; Kalivitis, Nikos; Stavroulas, Iasonas; Carbone, Samara; Jefferson, Anne; Park, Minsu; Schlag, Patrick; Iwamoto, Yoko; Aalto, Pasi; Äijälä, Mikko; Bukowiecki, Nicolas; Ehn, Mikael; Frank, Göran; Fröhlich, Roman; Frumau, Arnoud; Herrmann, Erik; Herrmann, Hartmut; Holzinger, Rupert; Kos, Gerard; Kulmala, Markku; Mihalopoulos, Nikolaos; Nenes, Athanasios; O'Dowd, Colin; Petäjä, Tuukka; Picard, David; Pöhlker, Christopher; Pöschl, Ulrich; Poulain, Laurent; Prévôt, André Stephan Henry; Swietlicki, Erik; Andreae, Meinrat O.; Artaxo, Paulo; Wiedensohler, Alfred; Ogren, John; Matsuki, Atsushi; Yum, Seong Soo; Stratmann, Frank; Baltensperger, Urs; Gysel, Martin

    2018-02-01

    Aerosol-cloud interactions (ACI) constitute the single largest uncertainty in anthropogenic radiative forcing. To reduce the uncertainties and gain more confidence in the simulation of ACI, models need to be evaluated against observations, in particular against measurements of cloud condensation nuclei (CCN). Here we present a data set - ready to be used for model validation - of long-term observations of CCN number concentrations, particle number size distributions and chemical composition from 12 sites on 3 continents. Studied environments include coastal background, rural background, alpine sites, remote forests and an urban surrounding. Expectedly, CCN characteristics are highly variable across site categories. However, they also vary within them, most strongly in the coastal background group, where CCN number concentrations can vary by up to a factor of 30 within one season. In terms of particle activation behaviour, most continental stations exhibit very similar activation ratios (relative to particles > 20 nm) across the range of 0.1 to 1.0 % supersaturation. At the coastal sites the transition from particles being CCN inactive to becoming CCN active occurs over a wider range of the supersaturation spectrum. Several stations show strong seasonal cycles of CCN number concentrations and particle number size distributions, e.g. at Barrow (Arctic haze in spring), at the alpine stations (stronger influence of polluted boundary layer air masses in summer), the rain forest (wet and dry season) or Finokalia (wildfire influence in autumn). The rural background and urban sites exhibit relatively little variability throughout the year, while short-term variability can be high especially at the urban site. The average hygroscopicity parameter, κ, calculated from the chemical composition of submicron particles was highest at the coastal site of Mace Head (0.6) and lowest at the rain forest station ATTO (0.2-0.3). We performed closure studies based on κ-Köhler theory

  4. Elevated metallothionein-bound cadmium concentrations in urine from bladder carcinoma patients, investigated by size exclusion chromatography-inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Christian [Department of Molecular Trace Element Research in the Life Sciences, Helmholtz Centre Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany)], E-mail: wolf@helmholtz-berlin.de; Strenziok, Romy [Department of Urology, Charite University Medicine Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin (Germany); Kyriakopoulos, Antonios [Department of Molecular Trace Element Research in the Life Sciences, Helmholtz Centre Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany)

    2009-01-12

    Cadmium is discussed as being involved in the development of transitional cell carcinoma (TCC) of the bladder and can be observed in urine of these patients. Investigations of urinary samples from bladder cancer patients and normal controls were carried out with special emphasis on metallothionein (MT)-bound cadmium. Compounds that are constituents of urine were separated in urine samples by means of size exclusion chromatography and cadmium was monitored continuously with a hyphenated inductively coupled plasma mass spectrometry (ICP-MS) system. MT-bound cadmium was quantified by peak area integration, taking into account the intensity of the rhodium signal which was added continuously before ICP-MS detection. The obtained results show that urinary cadmium is predominantly bound to the observed MT-fraction. The median of the MT-bound cadmium concentration in the control group was found to be 0.8 {mu}g L{sup -1} whereas the cancer group has a median of 1.8 {mu}g L{sup -1}. The variance of the data in the cancer group is much higher than in the controls. However, the urinary MT-bound cadmium is significantly elevated in the cancer group; odds-ratio test: 7.11 (95% C.I.: 1.89-26.80), taking into account the total protein content. Due to the fact that only one main cadmium-containing fraction was observed, there is no necessity to separate the MT-fraction before cadmium determination in urine samples in future studies.

  5. Indoor and outdoor sources of size-resolved mass concentration of particulate matter in a school gym-implications for exposure of exercising children.

    Science.gov (United States)

    Braniš, Martin; Safránek, Jiří; Hytychová, Adéla

    2011-05-01

    It has been noticed many times that schools are buildings with high levels of particulate matter concentrations. Several authors documented that concentrations of particulate matter in indoor school microenvironments exceed limits recommended by WHO namely when school buildings are situated near major roads with high traffic densities. In addition, exercise under conditions of high particulate concentrations may increase the adverse health effects, as the total particle deposition increases in proportion to minute ventilation, and the deposition fraction nearly doubles from rest to intense exercise. Mass concentrations of size-segregated aerosol were measured simultaneously in an elementary school gym and an adjacent outdoor site in the central part of Prague by two pairs of collocated aerosol monitors-a fast responding photometer DusTrak and a five stage cascade impactor. To encompass seasonal and annual differences, 89 days of measurements were performed during ten campaigns between 2005 and 2009. The average (all campaigns) outdoor concentration of PM(2.5) (28.3 μg m(-3)) measured by the cascade impactors was higher than the indoor value (22.3 μg m(-3)) and the corresponding average from the nearest fixed site monitor (23.6 μg m(-3)). Indoor and outdoor PM(2.5) concentrations exceeded the WHO recommended 24-h limit in 42% and 49% of the days measured, respectively. The correlation coefficient (r) between corresponding outdoor and indoor aerosol sizes increased with decreasing aerodynamic diameter of the collected particles (r = 0.32-0.87), suggesting a higher infiltration rate of fine and quasi-ultrafine particles. Principal component analysis revealed five factors explaining more than 82% of the data variability. The first two factors reflected a close association between outdoor and indoor fine and quasi-ultrafine particles confirming the hypothesis of high infiltration rate of particles from outdoors. The third factor indicated that human

  6. A multilayer concentric filter device to diminish clogging for separation of particles and microalgae based on size.

    Science.gov (United States)

    Chen, Chih-Chung; Chen, Yu-An; Liu, Yi-Ju; Yao, Da-Jeng

    2014-04-21

    Microalgae species have great economic importance; they are a source of medicines, health foods, animal feeds, industrial pigments, cosmetic additives and biodiesel. Specific microalgae species collected from the environment must be isolated for examination and further application, but their varied size and culture conditions make their isolation using conventional methods, such as filtration, streaking plate and flow cytometric sorting, labour-intensive and costly. A separation device based on size is one of the most rapid, simple and inexpensive methods to separate microalgae, but this approach encounters major disadvantages of clogging and multiple filtration steps when the size of microalgae varies over a wide range. In this work, we propose a multilayer concentric filter device with varied pore size and is driven by a centrifugation force. The device, which includes multiple filter layers, was employed to separate a heterogeneous population of microparticles into several subpopulations by filtration in one step. A cross-flow to attenuate prospective clogging was generated by altering the rate of rotation instantly through the relative motion between the fluid and the filter according to the structural design of the device. Mixed microparticles of varied size were tested to demonstrate that clogging was significantly suppressed due to a highly efficient separation. Microalgae in a heterogeneous population collected from an environmental soil collection were separated and enriched into four subpopulations according to size in a one step filtration process. A microalgae sample contaminated with bacteria and insect eggs was also tested to prove the decontamination capability of the device.

  7. Synthesis of silica nanoparticles for the manufacture of porous carbon membrane and particle size analysis by sedimentation field-flow fractionation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Ho; Eum, Chul; Hun; Choi, Seong Ho; Kim, Woon Jung [Dept. of Chemistry, Hannam University, Daejeon (Korea, Republic of)

    2016-11-15

    Silica nanoparticles were synthesized by emulsion polymerization by mixing ethanol, ammonium hydroxide, water, and tetraethyl orthosilicate. An apparatus was designed and assembled for a large-scale synthesis of silica nanospheres, which was aimed for uniform mixing of the reactants. Then sedimentation field-flow fractionation (SdFFF) was used to determine the size distribution of the silica nanoparticles. SdFFF provided mass-based separation where the retention time increased with the particle size, thus the size distribution of silica nanoparticles obtained from SdFFF appeared more accurate than that from dynamic light scattering, particularly for those having broad and multimodal size distributions. A disk-shaped porous carbon membrane (PCM) was manufactured for application as an adsorbent by pressurizing the silica particles, followed by calcination. Results showed that PCM manufactured in this study has relatively high surface area and temperature stability. The PCM surface was modified by attaching a carboxyl group (PCM-COOH) and then by incorporating silver (PCM-COOH-Ag). The amount of COOH group on PCM was measured electrochemically by cyclic voltammetry, and the surface area, pore size, pore volume of PCM-COOH-Ag by Brunauer–Emmet–Teller measurement. The surface area was 40.65 and reduced to 13.02 after loading a COOH group then increased up to 30.37 after incorporating Ag.

  8. Concentrations of tocols and γ-oryzanol compounds in rice bran oil obtained by fractional extraction with supercritical carbon dioxide.

    Science.gov (United States)

    Yoon, Sung Won; Pyo, Young-Gil; Lee, Junsoo; Lee, Jeom-Sig; Kim, Byung Hee; Kim, In-Hwan

    2014-01-01

    Rice bran oil (RBO) is a good source of several commercially important bioactive phytochemicals, such as tocols (i.e. tocopherols and tocotrienols) and ferulic esters of sterols (i.e. γ-oryzanol). The aims of the present study were to examine the effects of different pressure and temperature combinations on the fractional extraction of RBO using supercritical carbon dioxide (SC-CO2) and to assess the levels of tocols homologues and γ-oryzanol components in the resulting oil fractions. Fractional extraction of rice bran oil was performed using SC-CO2 at either 27.6 or 41.4 MPa and either 40 or 60°C. The effects of the four different pressure and temperature combinations on the levels of seven tocols homologues (α-, β-, γ- and δ-tocopherol and α-, γ- and δ-tocotrienol) and the four major components of γ-oryzanol in the resulting oil fractions were investigated. Superior extraction efficiency was obtained using the higher pressure of 41.4 MPa. The tocols (particularly α-tocopherol and α-tocotrienol) were recovered early in the extraction process, while the γ-oryzanol compounds were obtained in the later stages. With regard to SC-CO2 extraction, tocols are more soluble than γ-oryzanol components, α-tocopherol is the most soluble of the tocols and the four γ-oryzanol components all have similar solubilities. Valuable data on solubilities of tocols homologues in SC-CO2 were provided from present study.

  9. The effect of grain size and surface area on organic matter, lignin and carbohydrate concentration, and molecular compositions in Peru Margin sediments

    Science.gov (United States)

    Bergamaschi, Brian A.; Tsamakis, Elizabeth; Keil, Richard G.; Eglinton, Timothy I.; Montluçon, Daniel B.; Hedges, John I.

    1997-03-01

    A C-rich sediment sample from the Peru Margin was sorted into nine hydrodynamically-determined grain size fractions to explore the effect of grain size distribution and sediment surface area on organic matter content and composition. The neutral monomeric carbohydrate composition, lignin oxidation product yields, total organic carbon, and total nitrogen contents were determined independently for each size fraction, in addition to sediment surface area and abundance of biogenic opal. The percent organic carbon and percent total nitrogen were strongly related to surface area in these sediments. In turn, the distribution of surface area closely followed mass distribution among the textural size classes, suggesting hydrodynamic controls on grain size also control organic carbon content. Nevertheless, organic compositional distinctions were observed between textural size classes. Total neutral carbohydrate yields in the Peru Margin sediments were found to closely parallel trends in total organic carbon, increasing in abundance among grain size fractions in proportion to sediment surface area. Coincident with the increases in absolute abundance, rhamnose and mannose increased as a fraction of the total carbohydrate yield in concert with surface area, indicating these monomers were preferentially represented in carbohydrates associated with surfaces. Lignin oxidation product yields varied with surface area when normalized to organic carbon, suggesting that the terrestrially-derived component may be diluted by sorption of marine derived material. Lignin-based parameters suggest a separate source for terrestrially derived material associated with sand-size material as opposed to that associated with silts and clays.

  10. Size distribution and concentration of soot generated in oil and gas-fired residential boilers under different combustion conditions

    Science.gov (United States)

    Jiménez, Santiago; Barroso, Jorge; Pina, Antonio; Ballester, Javier

    2016-05-01

    In spite of the relevance of residential heating burners in the global emission of soot particles to the atmosphere, relatively little information on their properties (concentration, size distribution) is available in the literature, and even less regarding the dependence of those properties on the operating conditions. Instead, the usual procedure to characterize those emissions is to measure the smoke opacity by several methods, among which the blackening of a paper after filtering a fixed amount of gas (Bacharach test) is predominant. In this work, the size distributions of the particles generated in the combustion of a variety of gaseous and liquid fuels in a laboratory facility equipped with commercial burners have been measured with a size classifier coupled to a particle counter in a broad range of operating conditions (air excesses), with simultaneous determination of the Bacharach index. The shape and evolution of the distribution with progressively smaller oxygen concentrations depends essentially on the state of the fuel: whereas the combustion of the gases results in monomodal distributions that 'shift' towards larger diameters, in the case of the gas-oils an ultrafine mode is always observed, and a secondary mode of coarse particle grows in relevance. In both cases, there is a strong, exponential correlation between the total mass concentration and the Bacharach opacity index, quite similar for both groups of fuels. The empirical expressions proposed may allow other researchers to at least estimate the emissions of numerous combustion facilities routinely characterized by their smoke opacities.

  11. Rheological and droplet size analysis of W/O/W multiple emulsions containing low concentrations of polymeric emulsifiers

    Directory of Open Access Journals (Sweden)

    DRAGANA D. VASILJEVIĆ

    2009-07-01

    Full Text Available Multiple emulsions are complex dispersion systems which have many potential applications in pharmaceutics, cosmetics and the food industry. In practice, however, significant problems may arise because of their thermodynamic instability. In this study, W/O/W multiple emulsion systems containing low concentration levels of lipophilic polymeric primary emulsifiers cetyl dimethicone copolyol and PEG–30 dipolyhydroxystearate were evaluated. The concentrations of the primary emulsifiers were set at 1.6 and 2.4 % w/w in the final emulsions. Rheological and droplet size analysis of the investigated samples showed that the type and concentration of the primary lipophilic polymeric emulsifier markedly affected the characteristics of the multiple emulsions. The multiple emulsion prepared with 2.4 % w/w PEG–30 dipolyhydroxystearate as the primary emulsifier exhibited the highest apparent viscosity, yield stress and elastic modulus values, as well as the smallest droplet size. Furthermore, these parameters remained relatively constant over the study period, confirming the high stability of the investigated sample. The results obtained indicate that the changes observed in the investigated samples over time could be attributed to the swelling/breakdown mechanism of the multiple droplets. Such changes could be adequately monitored by rheological and droplet size analysis.

  12. Evaluation of in vitro cytoxicity and genotoxicity of size-fractionated air particles sampled during road tunnel construction.

    Science.gov (United States)

    Dominici, Luca; Guerrera, Elena; Villarini, Milena; Fatigoni, Cristina; Moretti, Massimo; Blasi, Paolo; Monarca, Silvano

    2013-01-01

    In tunnel construction, workers exposed to dust from blasting, gases, diesel exhausts, and oil mist have shown higher risk for pulmonary diseases. A clear mechanism to explain how these pollutants determine diseases is lacking, and alveolar epithelium's capacity to ingest inhaled fine particles is not well characterized. The objective of this study was to assess the genotoxic effect exerted by fine particles collected in seven tunnels using the cytokinesis-block micronuclei test in an in vitro model on type II lung epithelium A549 cells. For each tunnel, five fractions with different aerodynamic diameters of particulate matter were collected with a multistage cascade sampler. The human epithelial cell line A549 was exposed to 0.2 m(3)/mL equivalent of particulate for 24 h before testing. The cytotoxic effects of particulate matter on A549 cells were also evaluated in two different viability tests. In order to evaluate the cells' ability to take up fine particles, imaging with transmission electron microscopy of cells after exposure to particulate matter was performed. Particle endocytosis after 24 h exposure was observed as intracellular aggregates of membrane-bound particles. This morphologic evidence did not correspond to an increase in genotoxicity detected by the micronucleus test.

  13. Fast Centrifugal Partition Chromatography Fractionation of Concentrated Agave (Agave salmiana) Sap to Obtain Saponins with Apoptotic Effect on Colon Cancer Cells.

    Science.gov (United States)

    Santos-Zea, Liliana; Fajardo-Ramírez, Oscar R; Romo-López, Irasema; Gutiérrez-Uribe, Janet A

    2016-03-01

    Separation of potentially bioactive components from foods and plant extracts is one of the main challenges for their study. Centrifugal partition chromatography has been a successful technique for the screening and identification of molecules with bioactive potential, such as steroidal saponins. Agave is a source of steroidal saponins with anticancer potential, though the activity of these compounds in concentrated agave sap has not been yet explored. In this study, fast centrifugal partition chromatography (FCPC) was used coupled with in vitro tests on HT-29 cells as a screening procedure to identify apoptotic saponins from an acetonic extract of concentrated agave sap. The three most bioactive fractions obtained by FCPC at partition coefficients between 0.23 and 0.4 contained steroidal saponins, predominantly magueyoside b. Flow cytometry analysis determined that the fraction rich in kammogenin and manogenin glycosides induced apoptosis, but when gentrogenin and hecogenin glycosides were also found in the fraction, a necrotic effect was observed. In conclusion, this study provides the evidence that steroidal saponins in concentrated agave sap were potential inductors of apoptosis and that it was possible to separate them using fast centrifugal partition chromatography.

  14. Sistema laboratorial de fracionamento de carboidratos de concentrados energéticos = Laboratorial system of carbohydrate fractions of energetic concentrate

    Directory of Open Access Journals (Sweden)

    Raquel Franco de Lima

    2006-04-01

    Full Text Available O objetivo deste estudo foi avaliar um sistema laboratorial de fracionamento para carboidratos para identificar e quantificar as frações que compõem esse nutriente em grãos e subprodutos. Foram determinadas as frações: açúcares simples (AS pelo método colorimétrico fenol-sulfúrico; amido disponível (AD e amido resistente (AR por digestões enzimáticas; fibra total (FT pelo método enzímico-gravimétrico; fibra em detergente neutro (FDN e fibra solúvel (FS, estimada pela diferença FT-FDN dos grãos de milho e sorgo, polpa de citrus, farelo de trigo, triguilho e farelo de arroz integral. Os coeficientes de variação para as frações AS, AD, AR, FT e FDN variaram de 4,81% a 19,17%; 4,58% a 15,03%; 2,42% a 9,91%; 1,23% a 8,23% e 1,16% a 8,42%, respectivamente, caracterizando uma boa repetibilidade das técnicas adotadas. O fracionamento identificou os principais grupos de carboidratos que compõem os alimentos e pode servir de referência para trabalhos futuros.The aim of this work was to evaluate a laboratorial system of carbohydrate fractions to identify and quantify the fractions that compose this nutrient. The following fractions were determined: simple sugars (SS using the colorimetric phenol-sulfuric method; digestible starch (DS and resistant starch (RS by enzymatic digestions; total fiber (TF using the enzymic-gravimetric method; neutral detergent fiber (NDF and soluble fiber (SF estimated by difference TF - NDF, in grains of corn and sorghum, citric pulp, wheat middlings, wheat mills and rice bran. The coefficient of variation for fractions SS, DS, RS, TF and NDF varied from 4.81 to 19.17%; 4.58 to 15.03%; 2.42 to 9.91%; 1.23 to 8.23% and 1.16 to 8.42%; respectively. A good repeatability of the method used was observed. The fraction identified the main groups of carbohydrates composed on the food and it can be a reference to future works.

  15. High throughput, high resolution enzymatic lithography process: effect of crystallite size, moisture, and enzyme concentration.

    Science.gov (United States)

    Mao, Zhantong; Ganesh, Manoj; Bucaro, Michael; Smolianski, Igor; Gross, Richard A; Lyons, Alan M

    2014-12-08

    By bringing enzymes into contact with predefined regions of a surface, a polymer film can be selectively degraded to form desired patterns that find a variety of applications in biotechnology and electronics. This so-called "enzymatic lithography" is an environmentally friendly process as it does not require actinic radiation or synthetic chemicals to develop the patterns. A significant challenge to using enzymatic lithography has been the need to restrict the mobility of the enzyme in order to maintain control of feature sizes. Previous approaches have resulted in low throughput and were limited to polymer films only a few nanometers thick. In this paper, we demonstrate an enzymatic lithography system based on Candida antartica lipase B (CALB) and poly(ε-caprolactone) (PCL) that can resolve fine-scale features, (<1 μm across) in thick (0.1-2.0 μm) polymer films. A Polymer Pen Lithography (PPL) tool was developed to deposit an aqueous solution of CALB onto a spin-cast PCL film. Immobilization of the enzyme on the polymer surface was monitored using fluorescence microscopy by labeling CALB with FITC. The crystallite size in the PCL films was systematically varied; small crystallites resulted in significantly faster etch rates (20 nm/min) and the ability to resolve smaller features (as fine as 1 μm). The effect of printing conditions and relative humidity during incubation is also presented. Patterns formed in the PCL film were transferred to an underlying copper foil demonstrating a "Green" approach to the fabrication of printed circuit boards.

  16. Facile synthesis of concentrated gold nanoparticles with low size-distribution in water: temperature and pH controls

    Directory of Open Access Journals (Sweden)

    Li Chunfang

    2011-01-01

    Full Text Available Abstract The citrate reduction method for the synthesis of gold nanoparticles (GNPs has known advantages but usually provides the products with low nanoparticle concentration and limits its application. Herein, we report a facile method to synthesize GNPs from concentrated chloroauric acid (2.5 mM via adding sodium hydroxide and controlling the temperature. It was found that adding a proper amount of sodium hydroxide can produce uniform concentrated GNPs with low size distribution; otherwise, the largely distributed nanoparticles or instable colloids were obtained. The low reaction temperature is helpful to control the nanoparticle formation rate, and uniform GNPs can be obtained in presence of optimized NaOH concentrations. The pH values of the obtained uniform GNPs were found to be very near to neutral, and the pH influence on the particle size distribution may reveal the different formation mechanism of GNPs at high or low pH condition. Moreover, this modified synthesis method can save more than 90% energy in the heating step. Such environmental-friendly synthesis method for gold nanoparticles may have a great potential in large-scale manufacturing for commercial and industrial demand.

  17. Facile synthesis of concentrated gold nanoparticles with low size-distribution in water: temperature and pH controls

    Science.gov (United States)

    Li, Chunfang; Li, Dongxiang; Wan, Gangqiang; Xu, Jie; Hou, Wanguo

    2011-07-01

    The citrate reduction method for the synthesis of gold nanoparticles (GNPs) has known advantages but usually provides the products with low nanoparticle concentration and limits its application. Herein, we report a facile method to synthesize GNPs from concentrated chloroauric acid (2.5 mM) via adding sodium hydroxide and controlling the temperature. It was found that adding a proper amount of sodium hydroxide can produce uniform concentrated GNPs with low size distribution; otherwise, the largely distributed nanoparticles or instable colloids were obtained. The low reaction temperature is helpful to control the nanoparticle formation rate, and uniform GNPs can be obtained in presence of optimized NaOH concentrations. The pH values of the obtained uniform GNPs were found to be very near to neutral, and the pH influence on the particle size distribution may reveal the different formation mechanism of GNPs at high or low pH condition. Moreover, this modified synthesis method can save more than 90% energy in the heating step. Such environmental-friendly synthesis method for gold nanoparticles may have a great potential in large-scale manufacturing for commercial and industrial demand.

  18. Size-resolved mass concentrations of iron oxide aerosols and size-resolved number concentrations of iron oxide aerosols collected from King Air aircraft in Yellow Sea and East China Sea from 2013-02-14 to 2013-03-10 (NCEI Accession 0162201)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains size-resolved mass concentrations of iron oxide aerosols and size-resolved number concentrations of iron oxide aerosols, measured using the...

  19. An assessment of the optimal timing and size of investments in concentrated solar power

    International Nuclear Information System (INIS)

    Massetti, Emanuele; Ricci, Elena Claire

    2013-01-01

    We extend the WITCH model to consider the possibility to produce and trade electricity generated by large-scale concentrated solar power plants (CSP) in highly productive areas that are connected to demand centers through High Voltage Direct Current cables. We test the attractiveness of the CSP option by imposing a global cap on Greenhouse gases concentration equal to 535 ppm CO 2 -eq in 2100, with and without constraints to the expansion of nuclear power and IGCC coal with carbon capture and storage (CCS). We find that it becomes optimal to produce with CSP from 2040 and to trade CSP electricity across the Mediterranean from 2050. Therefore projects like DESERTEC seem to be premature. After 2050, CSP electricity shares become significant. CSP has a high stabilization cost option value: depending on the constraints, it ranges between 2.1% and 4.1% of discounted GDP in the Middle East and North Africa (MENA), between 1.1. and 3.4 in China, between 0.2% and 1.2% in the USA, between 0.1 and 1.3% in Eastern Europe and between 0.1 and 0.4% in Western Europe. A moderate level of subsidy to invest more and earlier in CSP might increase welfare. However, large-scale deployment should occur after 2040. We also show that MENA countries have the incentive to form a cartel to sell electricity to Europe at a price higher than the marginal cost. This suggests that a hypothetical Mediterranean market for electricity should be carefully regulated. - Highlights: ► An extensive use of Concentrated Solar Power (CSP) will be optimal after 2050. ► Trade of CSP electricity between MENA and Europe will start in 2050. ► CSP reduces greatly the option value of nuclear power and coal with CCS. ► Learning externalities motivate moderate subsidies for earlier CSP investments. ► MENA countries have the incentive to form a cartel to sell electricity to Europe

  20. Influence of some atmospheric variables on the concentration and particle size distribution of sulfate in urban air

    Energy Technology Data Exchange (ETDEWEB)

    Wagman, J; Lee, Jr, R E; Axt, C J

    1967-01-01

    Variations in the particle size distribution and concentration of atmospheric sulfate during a week in each of four cities were assessed with regard to the influence of such factors as location, humidity, sulfur dioxide level and time of day. Average sulfate mass median equivalent diameters (MMD) in Cincinnati, Chicago and Fairfax (Ohio) were nearly the same (0.42 micron) despite large differences in sulfate concentration and heterodispersity. A higher MMD (0.66 micron) in downtown Philadelphia was at least partly attributable to the presence of dust generated by road construction near the sampling site. Sulfate MMD generally increased with increasing relative humidity, whereas sulfate concentration was more closely correlated with absolute humidity except when SO/sub 2/ levels exceeded 3pphm. Periodic variations in the sulfate parameters at the different locations were characterized by the lack of a consistent pattern and could not be explained on the basis of humidity changes alone.

  1. The role of meteorology on different sized aerosol fractions (PM₁₀, PM₂.₅, PM₂.₅-₁₀).

    Science.gov (United States)

    Pateraki, St; Asimakopoulos, D N; Flocas, H A; Maggos, Th; Vasilakos, Ch

    2012-03-01

    The scope of the present study is to assess the influence of meteorology on different diameter particles (PM(10), PM(2.5), PM(2.5-10)) during a 53 months long experimental campaign at an urban Mediterranean area. Except for the investigation of the wind, temperature and relative humidity role, day by day synoptic conditions were classified over the Attica peninsula in order to explore as well, the role of the synoptic scale atmospheric circulation. The strong dependence of the aerosols character on their various sources, not only explain the different diameter particles behavior and their differentiation with the inorganic pollutants but also highlights the need for an effective emission policy. High PM(10) and PM(2.5-10) concentrations found to be closely related to the southwesterly regime, suggesting long range transport from the 'polluted' south sector while the general prevalence of the secondary particles generation revealed the health hazard. PM(2.5) showed a weaker correlation than the bigger particles with both the circulation patterns and the parameters' fluctuations. Temporal pollutants variations were clearly governed by the emissions patterns while the low wind speed was not necessarily a good indicator of high concentration levels. Finally it was found that only during the open/close anticyclonic days and the southwesterly wind regime the morning levels were continuously higher than those of the night. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Evolution of the two-phase flow in a vertical tube-decomposition of gas fraction profiles according to bubble size classes using wire-mesh sensors

    Energy Technology Data Exchange (ETDEWEB)

    Prasser, H.M.; Krepper, E.; Lucas, D. [Forschungszentrum Rossendorf e.V., Dresden (Germany)

    2002-01-01

    The wire-mesh sensor developed by the Forschungszentrum Rossendorf produces sequences of instantaneous gas fraction distributions in a cross section with a time resolution of 1200 frames per second and a spatial resolution of about 2-3 mm. At moderate flow velocities (up to 1-2 m.s{sup -1}), bubble size distributions can be obtained, since each individual bubble is mapped in several successive distributions. The method was used to study the evolution of the bubble size distribution in a vertical two-phase flow. For this purpose, the sensor was placed downstream of an air injector, the distance between air injection and sensor was varied. The bubble identification algorithm allows to select bubbles of a given range of the effective diameter and to calculate partial gas fraction profiles for this diameter range. In this way, the different behaviour of small and large bubbles in respect to the action of the lift force was observed in a mixture of small and large bubbles. (authors)

  3. Escape and fractionation of volatiles and noble gases: from Mars-sized planetary embryos to growing protoplanets

    Science.gov (United States)

    Odert, Petra; Lammer, Helmut; Erkaev, Nikolai V.; Nikolaou, Athanasia; Lichtenegger, Herbert I. M.; Johnstone, Colin P.; Kislyakova, Kristina G.; Leitzinger, Martin; Tosi, Nicola

    2017-04-01

    Planetary embryos form larger planetary objects via collisions. Such Moon- to Mars-sized bodies can have magma oceans. During the solidification of their magma oceans planetary embryos may therefore degas significant amounts of their volatiles, forming H2O/CO2 dominated steam atmospheres. Such atmospheres may escape efficiently due to the low gravity of these objects and the high EUV emission of the young host star. Planets forming from such building blocks could therefore be drier than expected. We model the energy-limited outflow of hydrogen which is able to drag along heavier species such as O and CO2. We take into account different stellar EUV evolution tracks to investigate the loss of steam atmospheres from Mars-sized planetary embryos at different orbital distances. We find that the estimated envelopes are typically lost within a few to a few tens of Myr. Moreover, we address the influence on protoplanet evolution using Venus as an example. We investigate different early evolution scenarios and constrain realistic cases by comparing modeled noble gas isotope ratios with presently observed ones. We are able to reproduce current ratios by assuming either a pure steam atmosphere or a mixture with accreted hydrogen from the protoplanetary nebula. Despite being able to find solutions for different parameter combinations, our results favor a low-activity Sun with possibly a small amount of residual H from the protoplanetary nebula. In other cases too much CO2 is lost during evolution, which is inconsistent with Venus' present atmosphere. A critical issue is likely the time at which the initial steam atmosphere is outgassed.

  4. [Black carbon content and distribution in different particle size fractions of forest soils in the middle part of Great Xing'an Mountains, China.

    Science.gov (United States)

    Xu, Jia Hui; Gao, Lei; Cui, Xiao Yang

    2017-10-01

    Soil black carbon (BC) is considered to be the main component of passive C pool because of its inherent biochemical recalcitrance. In this paper, soil BC in the middle part of Great Xing'an Mountains was quantified, the distribution of BC in different particle size fractions was analyzed, and BC stabilization mechanism and its important role in soil C pool were discussed. The results showed that BC expressed obvious accumulation in surface soil, accounting for about 68.7% in the whole horizon (64 cm), and then decreased with the increasing soil depth, however, BC/OC showed an opposite pattern. Climate conditions redistributed BC in study area, and the soil under cooler and moister conditions would sequester more BC. BC proportion in different particle size fractions was in the order of clay>silt>fine sand>coarse sand. Although BC content in clay was the highest and was enhanced with increasing soil depth, BC/OC in clay did not show a marked change. Thus, the rise of BC/OC was attributed to the preservation of BC particles in the fine sand and silt fractions. Biochemical recalcitrance was the main stabilization mechanism for surface BC, and with the increasing soil depth, the chemical protection from clay mineral gradually played a predominant role. BC not only was the essential component of soil stable carbon pool, but also took up a sizable proportion in particulate organic carbon pool. Therefore, the storage of soil stable carbon and the potential of soil carbon sequestration would be enhanced owing to the existence of BC.

  5. Contrasting food web factor and body size relationships with Hg and Se concentrations in marine biota.

    Directory of Open Access Journals (Sweden)

    Roxanne Karimi

    Full Text Available Marine fish and shellfish are primary sources of human exposure to mercury, a potentially toxic metal, and selenium, an essential element that may protect against mercury bioaccumulation and toxicity. Yet we lack a thorough understanding of Hg and Se patterns in common marine taxa, particularly those that are commercially important, and how food web and body size factors differ in their influence on Hg and Se patterns. We compared Hg and Se content among marine fish and invertebrate taxa collected from Long Island, NY, and examined associations between Hg, Se, body length, trophic level (measured by δ(15N and degree of pelagic feeding (measured by δ(13C. Finfish, particularly shark, had high Hg content whereas bivalves generally had high Se content. Both taxonomic differences and variability were larger for Hg than Se, and Hg content explained most of the variation in Hg:Se molar ratios among taxa. Finally, Hg was more strongly associated with length and trophic level across taxa than Se, consistent with a greater degree of Hg bioaccumulation in the body over time, and biomagnification through the food web, respectively. Overall, our findings indicate distinct taxonomic and ecological Hg and Se patterns in commercially important marine biota, and these patterns have nutritional and toxicological implications for seafood-consuming wildlife and humans.

  6. Contrasting Food Web Factor and Body Size Relationships with Hg and Se Concentrations in Marine Biota

    Science.gov (United States)

    Karimi, Roxanne; Frisk, Michael; Fisher, Nicholas S.

    2013-01-01

    Marine fish and shellfish are primary sources of human exposure to mercury, a potentially toxic metal, and selenium, an essential element that may protect against mercury bioaccumulation and toxicity. Yet we lack a thorough understanding of Hg and Se patterns in common marine taxa, particularly those that are commercially important, and how food web and body size factors differ in their influence on Hg and Se patterns. We compared Hg and Se content among marine fish and invertebrate taxa collected from Long Island, NY, and examined associations between Hg, Se, body length, trophic level (measured by δ15N) and degree of pelagic feeding (measured by δ13C). Finfish, particularly shark, had high Hg content whereas bivalves generally had high Se content. Both taxonomic differences and variability were larger for Hg than Se, and Hg content explained most of the variation in Hg:Se molar ratios among taxa. Finally, Hg was more strongly associated with length and trophic level across taxa than Se, consistent with a greater degree of Hg bioaccumulation in the body over time, and biomagnification through the food web, respectively. Overall, our findings indicate distinct taxonomic and ecological Hg and Se patterns in commercially important marine biota, and these patterns have nutritional and toxicological implications for seafood-consuming wildlife and humans. PMID:24019976

  7. Atmospheric aerosol sampling campaign in Budapest and K-puszta. Part 1. Elemental concentrations and size distributions

    International Nuclear Information System (INIS)

    Dobos, E.; Borbely-Kiss, I.; Kertesz, Zs.; Szabo, Gy.; Salma, I.

    2004-01-01

    Complete text of publication follows. Atmospheric aerosol samples were collected in a sampling campaign from 24 July to 1 Au- gust, 2003 in Hungary. The sampling were performed in two places simultaneously: in Budapest (urban site) and K-puszta (remote area). Two PIXE International 7-stage cascade impactors were used for aerosol sampling with 24 hours duration. These impactors separate the aerosol into 7 size ranges. The elemental concentrations of the samples were obtained by proton-induced X-ray Emission (PIXE) analysis. Size distributions of S, Si, Ca, W, Zn, Pb and Fe elements were investigated in K-puszta and in Budapest. Average rates (shown in Table 1) of the elemental concentrations was calculated for each stage (in %) from the obtained distributions. The elements can be grouped into two parts on the basis of these data. The majority of the particle containing Fe, Si, Ca, (Ti) are in the 2-8 μm size range (first group). These soil origin elements were found usually in higher concentration in Budapest than in K-puszta (Fig.1.). The second group consisted of S, Pb and (W). The majority of these elements was found in the 0.25-1 μm size range and was much higher in Budapest than in K-puszta. W was measured only in samples collected in Budapest. Zn has uniform distribution in Budapest and does not belong to the above mentioned groups. This work was supported by the National Research and Development Program (NRDP 3/005/2001). (author)

  8. Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

    Directory of Open Access Journals (Sweden)

    Casimiro Adrião Pio

    2014-05-01

    Full Text Available One year of, almost continuous, measurements of aerosol optical properties and chemical composition were performed at the outskirts of Praia, Santiago Island, Cape Verde, within the framework of CV-DUST (Atmospheric aerosol in Cape Verde region: seasonal evaluation of composition, sources and transport research project, during 2011. This article reports the aerosol number and mass concentration measurements using a GRIMM Optical Aerosol Spectrometer that provides number size discrimination into 31 size ranges from 0.25 to 32 µm. Time series of 5 min average PM10 concentrations revealed peak values higher than 1000 µg.m-3 during winter dust storm events originating over Northern Africa. The 24 hours average concentrations exceeded the World Health Organization (WHO guidelines for PM2.5 and PM10 in 20% and 30% of the 2001 days, respectively. Annual average mass concentrations (±standard deviation for PM1, PM2.5 and PM10 were 5±5, 19±21 and 48±64 µg.m-3, respectively. The annual PM2.5 and PM10 values were also above the limits prescribed by the WHO (10 and 20 µg.m-3, respectively. The aerosol mass size distribution revealed two main modes for particles smaller than 10 µm: a fine mode (0.7-0.8 µm, which possibly results of gas to particle conversion processes; and a coarse mode with maxima at 3-4 µm, which is associated with desert dust and sea salt sources. Within the coarse mode two sub-modes with maxima at 5-6 µm and 10-12 µm were frequently present.

  9. Escape and fractionation of volatiles and noble gases from Mars-sized planetary embryos and growing protoplanets

    Science.gov (United States)

    Odert, P.; Lammer, H.; Erkaev, N. V.; Nikolaou, A.; Lichtenegger, H. I. M.; Johnstone, C. P.; Kislyakova, K. G.; Leitzinger, M.; Tosi, N.

    2018-06-01

    Planetary embryos form protoplanets via mutual collisions, which can lead to the development of magma oceans. During their solidification, significant amounts of the mantles' volatile contents may be outgassed. The resulting H2O/CO2 dominated steam atmospheres may be lost efficiently via hydrodynamic escape due to the low gravity of these Moon- to Mars-sized objects and the high stellar EUV luminosities of the young host stars. Protoplanets forming from such degassed building blocks after nebula dissipation could therefore be drier than previously expected. We model the outgassing and subsequent hydrodynamic escape of steam atmospheres from such embryos. The efficient outflow of H drags along heavier species like O, CO2, and noble gases. The full range of possible EUV evolution tracks of a young solar-mass star is taken into account to investigate the atmospheric escape from Mars-sized planetary embryos at different orbital distances. The estimated envelopes are typically lost within a few to a few tens of Myr. Furthermore, we study the influence on protoplanetary evolution, exemplified by Venus. In particular, we investigate different early evolution scenarios and constrain realistic cases by comparing modeled noble gas isotope ratios with present observations. Isotope ratios of Ne and Ar can be reproduced, starting from solar values, under hydrodynamic escape conditions. Solutions can be found for different solar EUV histories, as well as assumptions about the initial atmosphere, assuming either a pure steam atmosphere or a mixture with accreted hydrogen from the protoplanetary nebula. Our results generally favor an early accretion scenario with a small amount of residual hydrogen from the protoplanetary nebula and a low-activity Sun, because in other cases too much CO2 is lost during evolution, which is inconsistent with Venus' present atmosphere. Important issues are likely the time at which the initial steam atmosphere is outgassed and/or the amount of CO2

  10. Simulating Aerosol Size Distribution and Mass Concentration with Simultaneous Nucleation, Condensation/Coagulation, and Deposition with the GRAPES-CUACE

    Science.gov (United States)

    Zhou, Chunhong; Shen, Xiaojing; Liu, Zirui; Zhang, Yangmei; Xin, Jinyuan

    2018-04-01

    A coupled aerosol-cloud model is essential for investigating the formation of haze and fog and the interaction of aerosols with clouds and precipitation. One of the key tasks of such a model is to produce correct mass and number size distributions of aerosols. In this paper, a parameterization scheme for aerosol size distribution in initial emission, which took into account the measured mass and number size distributions of aerosols, was developed in the GRAPES-CUACE [Global/Regional Assimilation and PrEdiction System-China Meteorological Administration (CMA) Unified Atmospheric Chemistry Environment model]—an online chemical weather forecast system that contains microphysical processes and emission, transport, and chemical conversion of sectional multi-component aerosols. In addition, the competitive mechanism between nucleation and condensation for secondary aerosol formation was improved, and the dry deposition was also modified to be in consistent with the real depositing length. Based on the above improvements, the GRAPES-CUACE simulations were verified against observational data during 1-31 January 2013, when a series of heavy regional haze-fog events occurred in eastern China. The results show that the aerosol number size distribution from the improved experiment was much closer to the observation, whereas in the old experiment the number concentration was higher in the nucleation mode and lower in the accumulation mode. Meanwhile, the errors in aerosol number size distribution as diagnosed by its sectional mass size distribution were also reduced. Moreover, simulations of organic carbon, sulfate, and other aerosol components were improved and the overestimation as well as underestimation of PM2.5 concentration in eastern China was significantly reduced, leading to increased correlation coefficient between simulated and observed PM2.5 by more than 70%. In the remote areas where bad simulation results were produced previously, the correlation coefficient

  11. Egg laying sequence influences egg mercury concentrations and egg size in three bird species: Implications for contaminant monitoring programs

    Science.gov (United States)

    Ackerman, Joshua T.; Eagles-Smith, Collin A.; Herzog, Mark P.; Yee, Julie L.; Hartman, C. Alex

    2016-01-01

    Bird eggs are commonly used in contaminant monitoring programs and toxicological risk assessments, but intra-clutch variation and sampling methodology could influence interpretability. We examined the influence of egg laying sequence on egg mercury concentrations and burdens in American avocets, black-necked stilts, and Forster's terns. The average decline in mercury concentrations between the first and last egg laid was 33% for stilts, 22% for terns, and 11% for avocets, and most of this decline occurred between the first and second eggs laid (24% for stilts, 18% for terns, and 9% for avocets). Trends in egg size with egg laying order were inconsistent among species and overall differences in egg volume, mass, length, and width were mercury concentrations generally declined by 16% between the first and second eggs laid. Despite the strong effect of egg laying sequence, most of the variance in egg mercury concentrations still occurred among clutches (75%-91%) rather than within clutches (9%-25%). Using simulations, we determined that to accurately estimate a population's mean egg mercury concentration using only a single random egg from a subset of nests, it would require sampling >60 nests to represent a large population (10% accuracy) or ≥14 nests to represent a small colony that contained <100 nests (20% accuracy).

  12. Water-soluble ions in atmospheric aerosols measured in five sites in the Yangtze River Delta, China: Size-fractionated, seasonal variations and sources

    Science.gov (United States)

    Wang, Honglei; Zhu, Bin; Shen, Lijuan; Xu, Honghui; An, Junlin; Xue, Guoqiang; Cao, Jinfei

    2015-12-01

    In order to investigate the regional variations of water-soluble ions (WSIs), size-resolved measurement of aerosol particles and WSIs was conducted by using Anderson Sampler and Ion Chromatography at five sites (Nanjing, Suzhou, Lin'an, Hangzhou and Ningbo) in the Yangtze River Delta (YRD) region, China in the Autumn of 2012 and Winter, Spring and Summer of 2013. WSIs exhibited obvious seasonal variations due to the monsoon conversion, with the highest level in winter and lowest level in summer. The aerosol mass concentrations and WSIs in different size segments varied with four seasons. The dominant ions concentrations in PM2.1 ranked in the order of SO42- > NO3- > NH4+ > Cl- > K+ > Ca2+, and the dominant ions concentrations in PM2.1-10 ranked in the order of Ca2+ > NO3- > SO42- > Cl- > NH4+ > Na+. The size spectra of mass and WSIs concentration peaked mostly at 0.43-0.65 μm in four seasons. The concentration discrepancies of WSIs in different cities were caused by the geographic locations and emission source. It's belonged to ammonium-rich distribution in PM2.1 and ammonium-poor distribution in PM2.1-10 in the YRD region. The impact of temperature on mass concentrations of NO3- and NH4+ in PM2.1 were stronger than those in PM2.1-10. PCA analysis shows that the sources of WSIs dominant by anthropogenic sources, soil particles or falling dust, sea salt and burning process.

  13. Luminescence study on Eu3+ doped Y2O3 nanoparticles: particle size, concentration and core-shell formation effects

    International Nuclear Information System (INIS)

    Singh, L Robindro; Ningthoujam, R S; Sudarsan, V; Srivastava, Iti; Singh, S Dorendrajit; Dey, G K; Kulshreshtha, S K

    2008-01-01

    Nanoparticles of Eu 3+ doped Y 2 O 3 (core) and Eu 3+ doped Y 2 O 3 covered with Y 2 O 3 shell (core-shell) are prepared by urea hydrolysis for 3 h in ethylene glycol medium at a relatively low temperature of 140 deg. C, followed by heating at 500 and 900 deg. C. Particle sizes determined from x-ray diffraction and transmission electron microscopic studies are 11 and 18 nm for 500 and 900 deg. C heated samples respectively. Based on the luminescence studies of 500 and 900 deg. C heated samples, it is confirmed that there is no particle size effect on the peak positions of Eu 3+ emission, and optimum luminescence intensity is observed from the nanoparticles with a Eu 3+ concentration of 4-5 at.%. A luminescence study establishes that the Eu 3+ environment in amorphous Y (OH) 3 is different from that in crystalline Y 2 O 3 . For a fixed concentration of Eu 3+ doping, there is a reduction in Eu 3+ emission intensity for core-shell nanoparticles compared to that of core nanoparticles, and this has been attributed to the concentration dilution effect. Energy transfer from the host to Eu 3+ increases with increase of crystallinity

  14. The influence of fractionated radiation therapy on plasma vascular endothelial growth factor (VEGF) concentration in dogs with spontaneous tumors and its impact on outcome

    International Nuclear Information System (INIS)

    Wergin, Melanie C.; Roos, Malgorzata; Inteeworn, Nathalie; Laluhova, Dagmar; Allemann, Katrin; Kaser-Hotz, Barbara

    2006-01-01

    Back ground and purpose: Vascular endothelial growth factor (VEGF), a specific pro-angiogenic factor is proposed to be involved in cancer progression and resistance to radiation therapy by promoting angiogenesis and by protecting endothelial cells from radiation induced apoptosis. The aim of this study, was first to assess the influence of ionizing radiation on plasma VEGF concentration in spontaneous canine tumors during fractionated radiation therapy with curative or palliative intent and second to analyze plasma VEGF concentration as predictor for treatment outcome. Patients and methods: For plasma VEGF analysis a human VEGF enzyme linked immunosorbent assay was used. Sixty dogs with various tumor types were included in this study. Dogs were irradiated with either low dose per fx (3-3.5 Gy per fraction, total dose: 42-49 Gy, group A: curative intent) or high dose per fx (6-8 Gy per fraction, total dose: 24-30 Gy, group B: palliative intent). Blood samples were taken before and after dose application at certain time points during therapy. Follow-up evaluation was performed for analysis of time to treatment failure and survival. Results: Repeated measures analysis showed no increase of plasma VEGF in dogs treated with fractionated radiation therapy (group A and B). Dichotomizing baseline plasma VEGF into two groups with high and low plasma VEGF, resulted in shorter time to treatment failure in dogs with high plasma VEGF levels (TTF, group A: P=0.038, group B: P=0.041). Conclusions: This study demonstrated that dogs with a plasma VEGF level higher than 5 pg/ml had a poorer outcome after radiation therapy. It is therefore, suggested, to use plasma VEGF as predictor for treatment outcome in radiation therapy

  15. Relationship between the Methane Production and the CNCPS Carbohydrate Fractions of Rations with Various Concentrate/roughage Ratios Evaluated Using Incubation Technique

    Directory of Open Access Journals (Sweden)

    Ruilan Dong

    2013-12-01

    Full Text Available The objective of the trial was to study the relationship between the methane (CH4 production and the Cornell Net Carbohydrate and Protein System (CNCPS carbohydrate fractions of feeds for cattle and the suitability of CNCPS carbohydrate fractions as the dietary variables in modeling the CH4 production in rumen fermentation. Forty-five rations for cattle with the concentrate/roughage ratios of 10:90, 20:80, 30:70, 40:60, and 50:50 were formulated as feed samples. The Menke and Steingass’s gas test was used for the measurement of CH4 production. The feed samples were incubated for 48 h and the CH4 production was analyzed using gas chromatography. Statistical analysis indicated that the CH4 production (mL was closely correlated with the CNCPS carbohydrate fractions (g, i.e. CA (sugars; CB1 (starch and pectin; CB2 (available cell wall in a multiple linear pattern: CH4 = (89.16±14.93 CA+ (124.10±13.90 CB1+(30.58±11.72 CB2+(3.28±7.19, R2 = 0.81, p<0.0001, n = 45. Validation of the model using 10 rations indicated that the CH4 production of the rations for cattle could accurately be predicted based on the CNCPS carbohydrate fractions. The trial indicated that the CNCPS carbohydrate fractions CA, CB1 and CB2 were suitable dietary variables for predicting the CH4 production in rumen fermentation in vitro.

  16. Unit-level voluntary turnover rates and customer service quality: implications of group cohesiveness, newcomer concentration, and size.

    Science.gov (United States)

    Hausknecht, John P; Trevor, Charlie O; Howard, Michael J

    2009-07-01

    Despite substantial growth in the service industry and emerging work on turnover consequences, little research examines how unit-level turnover rates affect essential customer-related outcomes. The authors propose an operational disruption framework to explain why voluntary turnover impairs customers' service quality perceptions. On the basis of a sample of 75 work units and data from 5,631 employee surveys, 59,602 customer surveys, and organizational records, results indicate that unit-level voluntary turnover rates are negatively related to service quality perceptions. The authors also examine potential boundary conditions related to the disruption framework. Of 3 moderators studied (group cohesiveness, group size, and newcomer concentration), results show that turnover's negative effects on service quality are more pronounced in larger units and in those with a greater concentration of newcomers.

  17. Long-term cloud condensation nuclei number concentration, particle number size distribution and chemical composition measurements at regionally representative observatories

    Directory of Open Access Journals (Sweden)

    J. Schmale

    2018-02-01

    Full Text Available Aerosol–cloud interactions (ACI constitute the single largest uncertainty in anthropogenic radiative forcing. To reduce the uncertainties and gain more confidence in the simulation of ACI, models need to be evaluated against observations, in particular against measurements of cloud condensation nuclei (CCN. Here we present a data set – ready to be used for model validation – of long-term observations of CCN number concentrations, particle number size distributions and chemical composition from 12 sites on 3 continents. Studied environments include coastal background, rural background, alpine sites, remote forests and an urban surrounding. Expectedly, CCN characteristics are highly variable across site categories. However, they also vary within them, most strongly in the coastal background group, where CCN number concentrations can vary by up to a factor of 30 within one season. In terms of particle activation behaviour, most continental stations exhibit very similar activation ratios (relative to particles  > 20 nm across the range of 0.1 to 1.0 % supersaturation. At the coastal sites the transition from particles being CCN inactive to becoming CCN active occurs over a wider range of the supersaturation spectrum. Several stations show strong seasonal cycles of CCN number concentrations and particle number size distributions, e.g. at Barrow (Arctic haze in spring, at the alpine stations (stronger influence of polluted boundary layer air masses in summer, the rain forest (wet and dry season or Finokalia (wildfire influence in autumn. The rural background and urban sites exhibit relatively little variability throughout the year, while short-term variability can be high especially at the urban site. The average hygroscopicity parameter, κ, calculated from the chemical composition of submicron particles was highest at the coastal site of Mace Head (0.6 and lowest at the rain forest station ATTO (0.2–0.3. We performed closure

  18. Effect of Porosity and Concentration Polarization on Electrolyte Diffusive Transport Parameters through Ceramic Membranes with Similar Nanopore Size

    Directory of Open Access Journals (Sweden)

    Virginia Romero

    2014-08-01

    Full Text Available Diffusive transport through nanoporous alumina membranes (NPAMs produced by the two-step anodization method, with similar pore size but different porosity, is studied by analyzing membrane potential measured with NaCl solutions at different concentrations. Donnan exclusion of co-ions at the solution/membrane interface seem to exert a certain control on the diffusive transport of ions through NPAMs with low porosity, which might be reduced by coating the membrane surface with appropriated materials, as it is the case of SiO2. Our results also show the effect of concentration polarization at the membrane surface on ionic transport numbers (or diffusion coefficients for low-porosity and high electrolyte affinity membranes, which could mask values of those characteristic electrochemical parameters.

  19. Size-separated particle fractions of stainless steel welding fume particles - A multi-analytical characterization focusing on surface oxide speciation and release of hexavalent chromium.

    Science.gov (United States)

    Mei, N; Belleville, L; Cha, Y; Olofsson, U; Odnevall Wallinder, I; Persson, K-A; Hedberg, Y S

    2018-01-15

    Welding fume of stainless steels is potentially health hazardous. The aim of this study was to investigate the manganese (Mn) and chromium (Cr) speciation of welding fume particles and their extent of metal release relevant for an inhalation scenario, as a function of particle size, welding method (manual metal arc welding, metal arc welding using an active shielding gas), different electrodes (solid wires and flux-cored wires) and shielding gases, and base alloy (austenitic AISI 304L and duplex stainless steel LDX2101). Metal release investigations were performed in phosphate buffered saline (PBS), pH 7.3, 37°, 24h. The particles were characterized by means of microscopic, spectroscopic, and electroanalytical methods. Cr was predominantly released from particles of the welding fume when exposed in PBS [3-96% of the total amount of Cr, of which up to 70% as Cr(VI)], followed by Mn, nickel, and iron. Duplex stainless steel welded with a flux-cored wire generated a welding fume that released most Cr(VI). Nano-sized particles released a significantly higher amount of nickel compared with micron-sized particle fractions. The welding fume did not contain any solitary known chromate compounds, but multi-elemental highly oxidized oxide(s) (iron, Cr, and Mn, possibly bismuth and silicon). Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  20. Carbon and Nitrogen Mineralization in Relation to Soil Particle-Size Fractions after 32 Years of Chemical and Manure Application in a Continuous Maize Cropping System.

    Directory of Open Access Journals (Sweden)

    Andong Cai

    Full Text Available Long-term manure application is recognized as an efficient management practice to enhance soil organic carbon (SOC accumulation and nitrogen (N mineralization capacity. A field study was established in 1979 to understand the impact of long-term manure and/or chemical fertilizer application on soil fertility in a continuous maize cropping system. Soil samples were collected from field plots in 2012 from 9 fertilization treatments (M0CK, M0N, M0NPK, M30CK, M30N, M30NPK, M60CK, M60N, and M60NPK where M0, M30, and M60 refer to manure applied at rates of 0, 30, and 60 t ha(-1 yr(-1, respectively; CK indicates no fertilizer; N and NPK refer to chemical fertilizer in the forms of either N or N plus phosphorus (P and potassium (K. Soils were separated into three particle-size fractions (2000-250, 250-53, and 250-53 μm > 53 μm fraction, whereas the amount of C and N mineralization followed the reverse order. In the <53 μm fraction, the M60NPK treatment significantly increased the amount of C and N mineralized (7.0 and 10.1 times, respectively compared to the M0CK treatment. Long-term manure application, especially when combined with chemical fertilizers, resulted in increased soil microbial biomass C and N, and a decreased microbial metabolic quotient. Consequently, long-term manure fertilization was beneficial to both soil C and N turnover and microbial activity, and had significant effect on the microbial metabolic quotient.

  1. Cholesterol concentrations in lipoprotein fractions separated by anion-exchange-high-performance liquid chromatography in healthy dogs and dogs with hypercholesterolemia.

    Science.gov (United States)

    Oda, Hitomi; Mori, Akihiro; Hirowatari, Yuji; Takoura, Toshie; Manita, Daisuke; Takahashi, Tomoya; Shono, Saori; Onozawa, Eri; Mizutani, Hisashi; Miki, Yohei; Itabashi, Yukiko; Sako, Toshinori

    2017-10-01

    Anion-exchange (AEX)-high-performance liquid chromatography (HPLC) for measurement of cholesterol can be used to separate serum lipoproteins (high-density lipoprotein (HDL); low-density lipoprotein (LDL); intermediate-density lipoprotein (IDL); very-low-density lipoprotein (VLDL)) in humans. However, AEX-HPLC has not been applied in veterinary practice. We had three objectives: (i) the validation of AEX-HPLC methods including the correlation of serum cholesterol concentration in lipoprotein fraction measured by AEX-HPLC and gel permeation-HPLC (GP-HPLC) in healthy dogs and those with hypercholesterolemia was investigated; (ii) the reference intervals of lipoprotein fractions measured by AEX-HPLC from healthy dogs (n=40) was established; (iii) lipoprotein fractions from the serum of healthy dogs (n=12) and dogs with hypercholesterolemia (n=23) were compared. Analytic reproducibility and precision of AEX-HPLC were acceptable. Positive correlation between serum concentrations of total cholesterol (Total-Chol), HDL cholesterol (HDL-Chol), LDL cholesterol (LDL-Chol)+IDL cholesterol (IDL-Chol), and VLDL cholesterol (VLDL-Chol) was noted for AEX-HPLC and GP-HPLC in healthy dogs and dogs with hypercholesterolemia. Reference intervals measured by AEX-HPLC for serum concentrations of Total-Chol, HDL-Chol, and LDL-Chol were determined to be 2.97-9.32, 2.79-6.57, 0.16-3.28mmol/L (2.5-97.5% interval), respectively. Furthermore, there was significant difference in lipoprotein profiles between healthy and dogs with hypercholesterolemia. These results suggest that AEX-HPLC can be used to evaluate lipoprotein profiles in dogs and could be a new useful indicator of hyperlipidemia in dogs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Effect of a dam on the optical properties of different-sized fractions of dissolved organic matter in a mid-subtropical drinking water source reservoir.

    Science.gov (United States)

    Sun, Qiyuan; Jiang, Juan; Zheng, Yuyi; Wang, Feifeng; Wu, Chunshan; Xie, Rong-Rong

    2017-11-15

    The presence of a dam on a river is believed to have a key role in affecting changes in the components of the chromophoric dissolved organic matter (CDOM) in reservoirs. However, questions remain about the mechanisms that control these changes. In this study, we used tangential ultrafiltration, fluorescence spectrum and phytoplankton cell density detection to explore the impacts of a dam on the CDOM components in the Shanzai Reservoir, a source of drinking water. The results demonstrated each CDOM size fraction comprised two main components, namely C1 (protein-like substance) and C2 (humic-like substance). The C1 content had a higher value in areas with slow flow than in the normal river channel, while the C2 contents were generally stable in the flow direction. The topography of the reservoir site affected the structure of the CDOM components based on changes in the hydraulic conditions caused by the dam. The variations in the CDOM components, hydraulic parameters and fluorescence indices in the river flow direction indicated that the contribution of the phytoplankton to the CDOM content increased as the distance to the dam decreased, phytoplankton metabolism enhanced C1 content of the 1-10kDa molecular weights range fraction. Further, the contributions of different phytoplankton biomass to C1 proved that the dam changed the hydraulic conditions, had secondary effects on the metabolism of the phytoplankton, and resulted in changes in the structure of the CDOM components. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Diesel vehicle and urban burning contributions to black carbon concentrations and size distributions in Tijuana, Mexico, during the Cal-Mex 2010 campaign

    Science.gov (United States)

    Takahama, S.; Russell, L. M.; Shores, C. A.; Marr, L. C.; Zheng, J.; Levy, M.; Zhang, R.; Castillo, E.; Rodriguez-Ventura, J. G.; Quintana, P. J. E.; Subramanian, R.; Zavala, M.; Molina, L. T.

    2014-05-01

    Black carbon (BC) was characterized by three complementary techniques - incandescence (single particle soot photometer, SP2, at Parque Morelos), light absorption (cavity ringdown spectrometer with integrating nephelometer, CRDS-Neph, at Parque Morelos and Aethalometers at seven locations), and volatility (volatility tandem differential mobility analyzer, V-TDMA) during the Cal-Mex 2010 campaign. SP2, CRDS-Neph, and Aethalometer measurements characterized the BC mass, and SP2 and V-TDMA measurements also quantified BC-containing particle number, from which mass-mean BC diameters were calculated. On average, the mass concentrations measured in Tijuana (1.8 ± 2.6 μg m-3 at Parque Morelos and 2.6 μg m-3 in other regions of Tijuana) were higher than in San Diego or the international border crossing (0.5 ± 0.6 μg m-3). The observed BC mass concentrations were attributable to nighttime urban burning activities and diesel vehicles, both from the local (Baja California) and transported (Southern California) diesel vehicle fleets. Comparisons of the SP2 and co-located Aethalometers indicated that the two methods measured similar variations in BC mass concentrations (correlation coefficients greater than 0.85), and the mass concentrations were similar for the BC particles identified from nighttime urban burning sources. When the BC source changed to diesel vehicle emissions, the SP2 mass concentrations were lower than the Aethalometer mass concentrations by about 50%, likely indicating a change in the mass absorption efficiency and quantification by the Aethalometers. At Parque Morelos there were up to three different-sized modes of BC mass in particles: one mode below 100 nm, one near 100 nm, and another between 200 and 300 nm. The mode between 200 and 300 nm was associated with urban burning activities that influenced the site during evening hours. When backtrajectories indicated that airmasses came from the south to the Parque Morelos site, BC mass in particles was

  4. Multistage-multiorifice flow fractionation (MS-MOFF): continuous size-based separation of microspheres using multiple series of contraction/expansion microchannels.

    Science.gov (United States)

    Sim, Tae Seok; Kwon, Kiho; Park, Jae Chan; Lee, Jeong-Gun; Jung, Hyo-Il

    2011-01-07

    Previously we introduced a novel hydrodynamic method using a multi-orifice microchannel for size-based particle separation, which is called a multi-orifice flow fractionation (MOFF). The MOFF has several advantages such as continuous, non-intrusive, and minimal power consumption. However, it has a limitation that the recovery yield is relatively low. Although the recovery may be increased by adjusting parameters such as the Reynolds number and central collecting region, poor purity inevitably followed. We newly designed and fabricated a microfluidic channel for multi-stage multi-orifice flow fractionation (MS-MOFF), which is made by combining three multi-orifice segments, and consists of 3 inlets, 3 filters, 3 multi-orifice segments and 5 outlets. The structure and dimensions of the MS-MOFF were determined by the hydrodynamic principles to have constant Reynolds numbers at each multi-orifice segment. Polystyrene microspheres of two different sizes (7 μm and 15 μm) were tested. With this device, we made an attempt to improve recovery and minimize loss of purity by collecting and re-separating non-selected particles of the first separation. The final recovery successfully increased from 73.2% to 88.7% while the final purity slightly decreased from 91.4% to 89.1% (for 15 μm). These values were never achievable with the single-stage MOFF (SS-MOFF) having only one multi-orifice segment in our previous work. The MS-MOFF channel will be useful for clinical applications, such as separation of circulating tumor cells (CTC) or rare cells from human blood samples.

  5. Size and metal concentration in the mangrove mussel Mytella guyanensis (Mollusca: Bivalva) from Baia de Sepetiba, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    de Lacerda, L.D.; Lima, N.R.W.; Pfeiffer, W.C.; Fiszman, M.

    1983-11-01

    The natural variability of metal concentrations in M. guyanensis was estimated. The chosen parameter was size, as it is well correlated with most other metabolic functions and is of major concern in developing monitoring programs. The sampled area is in the mangrove swamp of Itingussu, Baia de Sepetiba, Rio de Janerio State, an area with increasing industrial activity and consequently with moderate levels of heavy metals in the aquatic environment. The analysis of metals in shells showed a significant inverse relationship for all metals, presenting a constant trend not observed in soft tissues. As the mechanisms of metal uptake and excretion in shells are slower than those of soft tissues, shells should be used as monitoring instruments. The results suggest that the relation between metal concentration and size in mollusks is a significant factor to be considered in monitoring programs. These relationships vary with species, and care should be taken in considering results obtained in species from temperature regions and those from the tropics, even when the species are closely related. 7 references, 2 figures, 1 table.

  6. Tangential Flow Ultrafiltration: A “Green” Method for the Size Selection and Concentration of Colloidal Silver Nanoparticles

    Science.gov (United States)

    Anders, Catherine B.; Baker, Joshua D.; Stahler, Adam C.; Williams, Austin J.; Sisco, Jackie N.; Trefry, John C.; Wooley, Dawn P.; Pavel Sizemore, Ioana E.

    2012-01-01

    Nowadays, AgNPs are extensively used in the manufacture of consumer products,1 water disinfectants,2 therapeutics,1, 3 and biomedical devices4 due to their powerful antimicrobial properties.3-6 These nanoparticle applications are strongly influenced by the AgNP size and aggregation state. Many challenges exist in the controlled fabrication7 and size-based isolation4,8 of unfunctionalized, homogenous AgNPs that are free from chemically aggressive capping/stabilizing agents or organic solvents.7-13 Limitations emerge from the toxicity of reagents, high costs or reduced efficiency of the AgNP synthesis or isolation methods (e.g., centrifugation, size-dependent solubility, size-exclusion chromatography, etc.).10,14-18 To overcome this, we recently showed that TFU permits greater control over the size, concentration and aggregation state of Creighton AgNPs (300 ml of 15.3 μg ml-1 down to 10 ml of 198.7 μg ml-1) than conventional methods of isolation such as ultracentrifugation.19 TFU is a recirculation method commonly used for the weight-based isolation of proteins, viruses and cells.20,21 Briefly, the liquid sample is passed through a series of hollow fiber membranes with pore size ranging from 1,000 kD to 10 kD. Smaller suspended or dissolved constituents in the sample will pass through the porous barrier together with the solvent (filtrate), while the larger constituents are retained (retentate). TFU may be considered a "green" method as it neither damages the sample nor requires additional solvent to eliminate toxic excess reagents and byproducts. Furthermore, TFU may be applied to a large variety of nanoparticles as both hydrophobic and hydrophilic filters are available. The two main objectives of this study were: 1) to illustrate the experimental aspects of the TFU approach through an invited video experience and 2) to demonstrate the feasibility of the TFU method for larger volumes of colloidal nanoparticles and smaller volumes of retentate. First

  7. Physicochemical characterization of titanium dioxide pigments using various techniques for size determination and asymmetric flow field flow fractionation hyphenated with inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Helsper, Johannes P F G; Peters, Ruud J B; van Bemmel, Margaretha E M; Rivera, Zahira E Herrera; Wagner, Stephan; von der Kammer, Frank; Tromp, Peter C; Hofmann, Thilo; Weigel, Stefan

    2016-09-01

    Seven commercial titanium dioxide pigments and two other well-defined TiO2 materials (TiMs) were physicochemically characterised using asymmetric flow field flow fractionation (aF4) for separation, various techniques to determine size distribution and inductively coupled plasma mass spectrometry (ICPMS) for chemical characterization. The aF4-ICPMS conditions were optimised and validated for linearity, limit of detection, recovery, repeatability and reproducibility, all indicating good performance. Multi-element detection with aF4-ICPMS showed that some commercial pigments contained zirconium co-eluting with titanium in aF4. The other two TiMs, NM103 and NM104, contained aluminium as integral part of the titanium peak eluting in aF4. The materials were characterised using various size determination techniques: retention time in aF4, aF4 hyphenated with multi-angle laser light spectrometry (MALS), single particle ICPMS (spICPMS), scanning electron microscopy (SEM) and particle tracking analysis (PTA). PTA appeared inappropriate. For the other techniques, size distribution patterns were quite similar, i.e. high polydispersity with diameters from 20 to >700 nm, a modal peak between 200 and 500 nm and a shoulder at 600 nm. Number-based size distribution techniques as spICPMS and SEM showed smaller modal diameters than aF4-UV, from which mass-based diameters are calculated. With aF4-MALS calculated, light-scattering-based "diameters of gyration" (Øg) are similar to hydrodynamic diameters (Øh) from aF4-UV analyses and diameters observed with SEM, but much larger than with spICPMS. A Øg/Øh ratio of about 1 indicates that the TiMs are oblate spheres or fractal aggregates. SEM observations confirm the latter structure. The rationale for differences in modal peak diameter is discussed.

  8. Riboflavin-binding protein. Concentration and fractional saturation in chicken eggs as a function of dietary riboflavin.

    OpenAIRE

    White, H B; Armstrong, J; Whitehead, C C

    1986-01-01

    The concentration of riboflavin and riboflavin-binding protein were determined in the plasma, egg yolk and albumen from hens fed a riboflavin-deficient diet (1.2 mg/kg) supplemented with 0, 1, 2, 3, 10 and 40 mg of riboflavin/kg. We observed that the deposition of riboflavin in egg yolk and albumen is dependent on dietary riboflavin and reaches half-maximal values at about 2 mg of supplemental riboflavin/kg. The maximal amount of riboflavin deposited in the yolk is limited stoichiometrically ...

  9. Is ozonation environmentally benign for reverse osmosis concentrate treatment? Four-level analysis on toxicity reduction based on organic matter fractionation.

    Science.gov (United States)

    Weng, Jingxia; Jia, Huichao; Wu, Bing; Pan, Bingcai

    2018-01-01

    Ozonation is a promising option to treat reverse osmosis concentrate (ROC). However, a systematic understanding and assessment of ozonation on toxicity reduction is insufficient. In this study, ROC sampled from a typical industrial park wastewater treatment plant of China was fractionated into hydrophobic acid (HOA), hydrophobic base (HOB), hydrophobic neutral (HON), and hydrophilic fraction (HI). Systematic bioassays covering bacteria, algae, fish, and human cell lines were conducted to reveal the role of ozonation in toxicity variation of the four ROC fractions. HOA in the raw ROC exhibited the highest toxicity, followed by HON and HI. Ozonation significantly reduced total organic carbon (TOC) and UV 254 values in HOA, HON, and HI and their toxicity except in HOB. Correlation analysis indicated that chemical data (TOC and UV 254 ) of HOA and HON correlated well with their toxicities; however, poor correlations were observed for HOB and HI, suggesting that a battery of toxicity assays is necessary. This study indicates that TOC reduction during ozonation could not fully reflect the toxicity issue, and toxicity assessment is required in conjunction with the chemical data to evaluate the effectiveness of ozonation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Concentration of Immunoglobulins in Microfiltration Permeates of Skim Milk: Impact of Transmembrane Pressure and Temperature on the IgG Transmission Using Different Ceramic Membrane Types and Pore Sizes

    Directory of Open Access Journals (Sweden)

    Hans-Jürgen Heidebrecht

    2018-06-01

    Full Text Available The use of bioactive bovine milk immunoglobulins (Ig has been found to be an alternative treatment for certain human gastrointestinal diseases. Some methodologies have been developed with bovine colostrum. These are considered in laboratory scale and are bound to high cost and limited availability of the raw material. The main challenge remains in obtaining high amounts of active IgG from an available source as mature cow milk by the means of industrial processes. Microfiltration (MF was chosen as a process variant, which enables a gentle and effective concentration of the Ig fractions (ca. 0.06% in raw milk while reducing casein and lactose at the same time. Different microfiltration membranes (ceramic standard and gradient, pore sizes (0.14–0.8 µm, transmembrane pressures (0.5–2.5 bar, and temperatures (10, 50 °C were investigated. The transmission of immunoglobulin G (IgG and casein during the filtration of raw skim milk (<0.1% fat was evaluated during batch filtration using a single channel pilot plant. The transmission levels of IgG (~160 kDa were measured to be at the same level as the reference major whey protein β-Lg (~18 kDa at all evaluated pore sizes and process parameters despite the large difference in molecular mass of both fractions. Ceramic gradient membranes with a pore sizes of 0.14 µm showed IgG-transmission rates between 45% to 65% while reducing the casein fraction below 1% in the permeates. Contrary to the expectations, a lower pore size of 0.14 µm yielded fluxes up to 35% higher than 0.2 µm MF membranes. It was found that low transmembrane pressures benefit the Ig transmission. Upscaling the presented results to a continuous MF membrane process offers new possibilities for the production of immunoglobulin enriched supplements with well-known processing equipment for large scale milk protein fractionation.

  11. Concentration of Immunoglobulins in Microfiltration Permeates of Skim Milk: Impact of Transmembrane Pressure and Temperature on the IgG Transmission Using Different Ceramic Membrane Types and Pore Sizes.

    Science.gov (United States)

    Heidebrecht, Hans-Jürgen; Toro-Sierra, José; Kulozik, Ulrich

    2018-06-28

    The use of bioactive bovine milk immunoglobulins (Ig) has been found to be an alternative treatment for certain human gastrointestinal diseases. Some methodologies have been developed with bovine colostrum. These are considered in laboratory scale and are bound to high cost and limited availability of the raw material. The main challenge remains in obtaining high amounts of active IgG from an available source as mature cow milk by the means of industrial processes. Microfiltration (MF) was chosen as a process variant, which enables a gentle and effective concentration of the Ig fractions (ca. 0.06% in raw milk) while reducing casein and lactose at the same time. Different microfiltration membranes (ceramic standard and gradient), pore sizes (0.14⁻0.8 µm), transmembrane pressures (0.5⁻2.5 bar), and temperatures (10, 50 °C) were investigated. The transmission of immunoglobulin G (IgG) and casein during the filtration of raw skim milk (fat) was evaluated during batch filtration using a single channel pilot plant. The transmission levels of IgG (~160 kDa) were measured to be at the same level as the reference major whey protein β-Lg (~18 kDa) at all evaluated pore sizes and process parameters despite the large difference in molecular mass of both fractions. Ceramic gradient membranes with a pore sizes of 0.14 µm showed IgG-transmission rates between 45% to 65% while reducing the casein fraction below 1% in the permeates. Contrary to the expectations, a lower pore size of 0.14 µm yielded fluxes up to 35% higher than 0.2 µm MF membranes. It was found that low transmembrane pressures benefit the Ig transmission. Upscaling the presented results to a continuous MF membrane process offers new possibilities for the production of immunoglobulin enriched supplements with well-known processing equipment for large scale milk protein fractionation.

  12. Bioethanol Production by Calcium Alginate-Immobilised St1 Yeast System: Effects of Size of Beads, Ratio and Concentration

    Directory of Open Access Journals (Sweden)

    Masniroszaime Md Zain

    2011-12-01

    Full Text Available Immobilized yeast-cell technology posses several advantages in bioethanol production due to its potential to increase the ethanol yield by eliminating unit process used. Thus, process expenses in cell recovery and reutilization can be minimised. The aim of this study is to investigate the influence of three parameters (substrate concentrations, size of alginate beads and ratio of volume of beads to volume of medium on local isolated yeast (ST1 which immobilized using calcium alginate fermentation system. The most affected ethanol production by calcium alginate-immobilised ST1 yeast system were ratio of volume of the beads to the volume of substrate and concentration of LBS. Highest theoretical yield, 78% was obtained in ST1-alginate beads with the size of beads 0.5cm, ratio volume of beads to the volume of LBS media 0.4 and 150g/l concentration of LBS.ABSTRAK: Teknologi sel yis pegun memiliki beberapa kelebihan dalam penghasilan bioetanol kerana ia berpotensi meningkatkan pengeluaran etanol dengan menyingkirkan unit proses yang digunakan. Maka, proses pembiayaan dalam perolehan sel dan penggunaan semula boleh dikurangkan. Tujuan kajian ini adalah untuk mengkaji pengaruh tiga parameter (kepekatan substrat, saiz manik alginat dan nisbah isipadu manik terhadap isipadu bahantara ke atas sel tempatan terasing (local isolated yeast (ST1 yang dipegun menggunakan sistem penapaian kalsium alginat. Penghasilan etanol yang paling berkesan dengan menggunakan sistem yis ST1 kalsium alginat-pegun adalah dengan kadar nisbah isipadu manik terhadap isipadu substrat dan kepekatan LBS. Kadar hasil teori tertinggi iaitu 78% didapati menerusi manik alginat-ST1 dengan saiz manik 0.5cm, nisbah isipadu 0.4 terhadap perantara LBS dan kepekatan LBS sebanyak 150g/l. Normal 0 false false false EN-US X-NONE X-NONE

  13. Exact Solution of Fractional Diffusion Model with Source Term used in Study of Concentration of Fission Product in Uranium Dioxide Particle

    International Nuclear Information System (INIS)

    Fang Chao; Cao Jianzhu; Sun Lifeng

    2011-01-01

    The exact solution of fractional diffusion model with a location-independent source term used in the study of the concentration of fission product in spherical uranium dioxide (UO 2 ) particle is built. The adsorption effect of the fission product on the surface of the UO 2 particle and the delayed decay effect are also considered. The solution is given in terms of Mittag-Leffler function with finite Hankel integral transformation and Laplace transformation. At last, the reduced forms of the solution under some special physical conditions, which is used in nuclear engineering, are obtained and corresponding remarks are given to provide significant exact results to the concentration analysis of nuclear fission products in nuclear reactor. (nuclear physics)

  14. Seasonal variations in activity concentrations of 99Tc and 137Cs in the edible meat fraction of crabs and lobsters from the central Irish Sea.

    Science.gov (United States)

    Copplestone, D; Jackson, D; Hartnoll, R G; Johnson, M S; McDonald, P; Wood, N

    2004-01-01

    Discharges of most radionuclides into the Irish Sea from the BNFL site at Sellafield have decreased over the past 20 years or so. For a few radionuclides, however, discharges have peaked more recently. Notably, operation of the Enhanced Actinide Removal Plant (EARP) since 1994 has led to an increase in discharges of (99)Tc, as a result of the treatment of previously stored waste, with consequent increases in (99)Tc activity concentrations in a number of marine species, particularly in crustaceans such as lobsters. Previous research has considered the significance of factors such as sex and body weight on radionuclide concentrations. The current project set out to investigate whether seasonal variations in radionuclide concentrations in crabs and lobsters occur, with particular emphasis on the dynamics of (99)Tc and (137)Cs. Organisms were obtained from a site off the Isle of Man, where radionuclide concentrations were measurable but the site was sufficiently distant from Sellafield that the radionuclides were well mixed in the water column and not likely to be influenced by the pulsed nature of discharges of (99)Tc. Crab and lobster samples were collected monthly, between February 2000 and February 2001. Fifteen or 16 individuals (evenly split as male and female) of each species were collected on each occasion. Seawater samples were also collected over the 12-month period. Activity concentrations of (99)Tc in the edible meat fraction (both brown and white meat) ranged from 0.23 to 2.46 Bq kg(-1) (fresh weight (fw)) in crabs and 124 to 216 Bq kg(-1) (fw) in lobsters, with no observed seasonal variations. Activity concentrations of (137)Cs in both crab and lobster were lower, ranging from lobster meat (fw). A statistically significant increase in activity concentrations of (137)Cs in the meat was observed in the summer months for both crab and lobster. The cause has not been investigated but may be related to the laying down of energy reserves during the active

  15. Seasonal variations in activity concentrations of 99Tc and 137Cs in the edible meat fraction of crabs and lobsters from the central Irish Sea

    International Nuclear Information System (INIS)

    Copplestone, D.; Jackson, D.; Hartnoll, R.G.; Johnson, M.S.; McDonald, P.; Wood, N.

    2004-01-01

    Discharges of most radionuclides into the Irish Sea from the BNFL site at Sellafield have decreased over the past 20 years or so. For a few radionuclides, however, discharges have peaked more recently. Notably, operation of the Enhanced Actinide Removal Plant (EARP) since 1994 has led to an increase in discharges of 99 Tc, as a result of the treatment of previously stored waste, with consequent increases in 99 Tc activity concentrations in a number of marine species, particularly in crustaceans such as lobsters. Previous research has considered the significance of factors such as sex and body weight on radionuclide concentrations. The current project set out to investigate whether seasonal variations in radionuclide concentrations in crabs and lobsters occur, with particular emphasis on the dynamics of 99 Tc and 137 Cs. Organisms were obtained from a site off the Isle of Man, where radionuclide concentrations were measurable but the site was sufficiently distant from Sellafield that the radionuclides were well mixed in the water column and not likely to be influenced by the pulsed nature of discharges of 99 Tc. Crab and lobster samples were collected monthly, between February 2000 and February 2001. Fifteen or 16 individuals (evenly split as male and female) of each species were collected on each occasion. Seawater samples were also collected over the 12-month period. Activity concentrations of 99 Tc in the edible meat fraction (both brown and white meat) ranged from 0.23 to 2.46 Bq kg -1 (fresh weight (fw)) in crabs and 124 to 216 Bq kg -1 (fw) in lobsters, with no observed seasonal variations. Activity concentrations of 137 Cs in both crab and lobster were lower, ranging from -1 for crab meat (fw) and -1 for lobster meat (fw). A statistically significant increase in activity concentrations of 137 Cs in the meat was observed in the summer months for both crab and lobster. The cause has not been investigated but may be related to the laying down of energy reserves

  16. Seasonal variations in activity concentrations of {sup 99}Tc and {sup 137}Cs in the edible meat fraction of crabs and lobsters from the central Irish Sea

    Energy Technology Data Exchange (ETDEWEB)

    Copplestone, D. E-mail: copplest@liv.ac.uk; Jackson, D.; Hartnoll, R.G.; Johnson, M.S.; McDonald, P.; Wood, N

    2004-07-01

    Discharges of most radionuclides into the Irish Sea from the BNFL site at Sellafield have decreased over the past 20 years or so. For a few radionuclides, however, discharges have peaked more recently. Notably, operation of the Enhanced Actinide Removal Plant (EARP) since 1994 has led to an increase in discharges of {sup 99}Tc, as a result of the treatment of previously stored waste, with consequent increases in {sup 99}Tc activity concentrations in a number of marine species, particularly in crustaceans such as lobsters. Previous research has considered the significance of factors such as sex and body weight on radionuclide concentrations. The current project set out to investigate whether seasonal variations in radionuclide concentrations in crabs and lobsters occur, with particular emphasis on the dynamics of {sup 99}Tc and {sup 137}Cs. Organisms were obtained from a site off the Isle of Man, where radionuclide concentrations were measurable but the site was sufficiently distant from Sellafield that the radionuclides were well mixed in the water column and not likely to be influenced by the pulsed nature of discharges of {sup 99}Tc. Crab and lobster samples were collected monthly, between February 2000 and February 2001. Fifteen or 16 individuals (evenly split as male and female) of each species were collected on each occasion. Seawater samples were also collected over the 12-month period. Activity concentrations of {sup 99}Tc in the edible meat fraction (both brown and white meat) ranged from 0.23 to 2.46 Bq kg{sup -1} (fresh weight (fw)) in crabs and 124 to 216 Bq kg{sup -1} (fw) in lobsters, with no observed seasonal variations. Activity concentrations of {sup 137}Cs in both crab and lobster were lower, ranging from <0.16 to 0.85 Bq kg{sup -1} for crab meat (fw) and <0.3 to 3.3 Bq kg{sup -1} for lobster meat (fw). A statistically significant increase in activity concentrations of {sup 137}Cs in the meat was observed in the summer months for both crab and

  17. Temporal fluctuations in grain size, organic materials and iron concentrations in intertidal surface sediment of San Francisco Bay

    Science.gov (United States)

    Thomson-Becker, E. A.; Luoma, S.N.

    1985-01-01

    The physical and chemical characteristics of the oxidized surface sediment in an estuary fluctuate temporally in response to physical forces and apparently-fluctuating inputs. These characteristics, which include grain size and concentrations of organic materials and iron, will influence both trace-metal geochemistry and bioavailability. Temporal trends in the abundance of fine particles, total organic carbon content (TOC), absorbance of extractable organic material (EOM), and concentration of extractable iron in the sediment of San Francisco Bay were assessed using data sets containing approximately monthly samples for periods of two to seven years. Changes in wind velocity and runoff result in monthly changes in the abundance of fine particles in the intertidal zone. Fine-grained particles are most abundant in the late fall/early winter when runoff is elevated and wind velocities are low; particles are coarser in the summer when runoff is low and wind velocities are consistently high. Throughout the bay, TOC is linearly related to fine particle abundance (r = 0.61). Temporal variability occurs in this relationship, as particles are poor in TOC relative to percent of fine particles in the early rainy season. Iron-poor particles also appear to enter the estuary during high runoff periods; while iron is enriched on particle surfaces in the summer. Concentrations of extractable iron and absorbance of EOM vary strongly from year to year. Highest absorbances of EOM occurred in the first year following the drought in 1976-77, and in 1982 and 1983 when river discharge was unusually high. Extractable-iron concentrations were also highest in 1976-77, but were very low in 1982 and 1983. ?? 1985 Dr W. Junk Publishers.

  18. Egg-laying sequence influences egg mercury concentrations and egg size in three bird species: Implications for contaminant monitoring programs.

    Science.gov (United States)

    Ackerman, Joshua T; Eagles-Smith, Collin A; Herzog, Mark P; Yee, Julie L; Hartman, C Alex

    2016-06-01

    Bird eggs are commonly used in contaminant monitoring programs and toxicological risk assessments, but intraclutch variation and sampling methodology could influence interpretability. The authors examined the influence of egg-laying sequence on egg mercury concentrations and burdens in American avocets, black-necked stilts, and Forster's terns. The average decline in mercury concentrations between the first and last eggs laid was 33% for stilts, 22% for terns, and 11% for avocets, and most of this decline occurred between the first and second eggs laid (24% for stilts, 18% for terns, and 9% for avocets). Trends in egg size with egg-laying order were inconsistent among species, and overall differences in egg volume, mass, length, and width were eggs laid. Despite the strong effect of egg-laying sequence, most of the variance in egg mercury concentrations still occurred among clutches (75-91%) rather than within clutches (9%-25%). Using simulations, the authors determined that accurate estimation of a population's mean egg mercury concentration using only a single random egg from a subset of nests would require sampling >60 nests to represent a large population (10% accuracy) or ≥14 nests to represent a small colony that contained <100 nests (20% accuracy). Environ Toxicol Chem 2016;35:1458-1469. Published 2015 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America. Published 2015 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

  19. Determination of subcellular concentrations of soluble carbohydrates in rose petals during opening by nonaqueous fractionation method combined with infiltration-centrifugation method.

    Science.gov (United States)

    Yamada, Kunio; Norikoshi, Ryo; Suzuki, Katsumi; Imanishi, Hideo; Ichimura, Kazuo

    2009-11-01

    Petal growth associated with flower opening depends on cell expansion. To understand the role of soluble carbohydrates in petal cell expansion during flower opening, changes in soluble carbohydrate concentrations in vacuole, cytoplasm and apoplast of petal cells during flower opening in rose (Rosa hybrida L.) were investigated. We determined the subcellular distribution of soluble carbohydrates by combining nonaqueous fractionation method and infiltration-centrifugation method. During petal growth, fructose and glucose rapidly accumulated in the vacuole, reaching a maximum when petals almost reflected. Transmission electron microscopy showed that the volume of vacuole and air space drastically increased with petal growth. Carbohydrate concentration was calculated for each compartment of the petal cells and in petals that almost reflected, glucose and fructose concentrations increased to higher than 100 mM in the vacuole. Osmotic pressure increased in apoplast and symplast during flower opening, and this increase was mainly attributed to increases in fructose and glucose concentrations. No large difference in osmotic pressure due to soluble carbohydrates was observed between the apoplast and symplast before flower opening, but total osmotic pressure was much higher in the symplast than in the apoplast, a difference that was partially attributed to inorganic ions. An increase in osmotic pressure due to the continued accumulation of glucose and fructose in the symplast may facilitate water influx into cells, contributing to cell expansion associated with flower opening under conditions where osmotic pressure is higher in the symplast than in the apoplast.

  20. Positron emission mammography (PEM): Effect of activity concentration, object size, and object contrast on phantom lesion detection

    International Nuclear Information System (INIS)

    MacDonald, Lawrence R.; Wang, Carolyn L.; Eissa, Marna; Haseley, David; Kelly, Mary M.; Liu, Franklin; Parikh, Jay R.; Beatty, J. David; Rogers, James V.

    2012-01-01

    Purpose: To characterize the relationship between lesion detection sensitivity and injected activity as a function of lesion size and contrast on the PEM (positron emission mammography) Flex Solo II scanner using phantom experiments. Methods: Phantom lesions (spheres 4, 8, 12, 16, and 20 mm diameter) were randomly located in uniform background. Sphere activity concentrations were 3 to 21 times the background activity concentration (BGc). BGc was a surrogate for injected activity; BGc ranged from 0.44–4.1 kBq/mL, corresponding to 46–400 MBq injections. Seven radiologists read 108 images containing zero, one, or two spheres. Readers used a 5-point confidence scale to score the presence of spheres. Results: Sensitivity was 100% for lesions ≥12 mm under all conditions except for one 12 mm sphere with the lowest contrast and lowest BGc (60% sensitivity). Sensitivity was 100% for 8 mm spheres when either contrast or BGc was high, and 100% for 4 mm spheres only when both contrast and BGc were highest. Sphere contrast recovery coefficients (CRC) were 49%, 34%, 26%, 14%, and 2.8% for the largest to smallest spheres. Cumulative specificity was 98%. Conclusions: Phantom lesion detection sensitivity depends more on sphere size and contrast than on BGc. Detection sensitivity remained ≥90% for injected activities as low as 100 MBq, for lesions ≥8 mm. Low CRC in 4 mm objects results in moderate detection sensitivity even for 400 MBq injected activity, making it impractical to optimize injected activity for such lesions. Low CRC indicates that when lesions <8 mm are observed on PEM images they are highly tracer avid with greater potential of clinical significance. High specificity (98%) suggests that image statistical noise does not lead to false positive findings. These results apply to the 85 mm thick object used to obtain them; lesion detectability should be better (worse) for thinner (thicker) objects based on the reduced (increased) influence of photon attenuation.

  1. Tethered balloon-based particle number concentration, and size distribution vertical profiles within the lower troposphere of Shanghai

    Science.gov (United States)

    Zhang, Kun; Wang, Dongfang; Bian, Qinggen; Duan, Yusen; Zhao, Mengfei; Fei, Dongnian; Xiu, Guangli; Fu, Qingyan

    2017-04-01

    A tethered balloon-based measurement campaign of particle number concentration (PNC) and particle number size distribution (PNSD) in the size range of 15.7-661.2 nm was conducted within the lower troposphere of 1000 m in Shanghai, a Chinese megacity, during December of 2015. The meteorological conditions, PNC, and PNSD were synchronously measured at the ground-based station as well as by the tethered balloon. On ground level, the 88.2 nm particles were found to have the highest PNC. The Pearson correlation analysis based on the ground level data showed NO2 had a strong correlation with PNC. The synchronous measurement of PNC and PNSD at the ground station and on the tethered balloon showed that the 15.7-200 nm particles had higher PNC on ground level, but the PNC of 200-661.2 nm particles was higher at 400 m. One haze event (Dec 22nd-Dec 23rd) was selected for detailed discussion on the variation of vertical profiles of PNSD and PNC. The vertical distribution of characteristics of PNC and PNSD were observed and compared. Results indicated that the highest MaxDm (the diameter with the highest PNC) during those three launches all appeared at a high altitude, usually above 300 m. Compared to the clean days, the relatively bigger MaxDm at each height in the haze days also indicated regional transport of pollutants might contribute to more to that haze event.

  2. Topsoil and Deep Soil Organic Carbon Concentration and Stability Vary with Aggregate Size and Vegetation Type in Subtropical China

    Science.gov (United States)

    Fang, Xiang-Min; Chen, Fu-Sheng; Wan, Song-Ze; Yang, Qing-Pei; Shi, Jian-Min

    2015-01-01

    The impact of reforestation on soil organic carbon (OC), especially in deep layer, is poorly understood and deep soil OC stabilization in relation with aggregation and vegetation type in afforested area is unknown. Here, we collected topsoil (0–15 cm) and deep soil (30–45 cm) from six paired coniferous forests (CF) and broad-leaved forests (BF) reforested in the early 1990s in subtropical China. Soil aggregates were separated by size by dry sieving and OC stability was measured by closed-jar alkali-absorption in 71 incubation days. Soil OC concentration and mean weight diameter were higher in BF than CF. The cumulative carbon mineralization (Cmin, mg CO2-C kg-1 soil) varied with aggregate size in BF and CF topsoils, and in deep soil, it was higher in larger aggregates than in smaller aggregates in BF, but not CF. The percentage of soil OC mineralized (SOCmin, % SOC) was in general higher in larger aggregates than in smaller aggregates. Meanwhile, SOCmin was greater in CF than in BF at topsoil and deep soil aggregates. In comparison to topsoil, deep soil aggregates generally exhibited a lower Cmin, and higher SOCmin. Total nitrogen (N) and the ratio of carbon to phosphorus (C/P) were generally higher in BF than in CF in topsoil and deep soil aggregates, while the same trend of N/P was only found in deep soil aggregates. Moreover, the SOCmin negatively correlated with OC, total N, C/P and N/P. This work suggests that reforested vegetation type might play an important role in soil OC storage through internal nutrient cycling. Soil depth and aggregate size influenced OC stability, and deep soil OC stability could be altered by vegetation reforested about 20 years. PMID:26418563

  3. Luminescence study of Eu3+ doped GdVO4 nanoparticles: Concentration, particle size, and core/shell effects

    Science.gov (United States)

    Singh, N. Shanta; Ningthoujam, R. S.; Devi, L. Romila; Yaiphaba, N.; Sudarsan, V.; Singh, S. Dorendrajit; Vatsa, R. K.; Tewari, R.

    2008-11-01

    Nanoparticles of GdVO4 doped with Eu3+ and core/shell of GdVO4:Eu3+/GdVO4 are prepared by urea hydrolysis method using ethylene glycol as capping agent as well as reaction medium at 130 °C. Unit cell volume increases when GdVO4 is doped with Eu3+ indicating the substitution of Gd3+ lattice sites by Eu3+. From luminescence study, it is confirmed that there is no particle size effect on emission positions of Eu3+. Optimum luminescence intensity is found to be in 5-10 at. % Eu3+. Above these concentrations, luminescence intensity decreases due to concentration quenching effect. There is an enhancement in luminescence intensity of core/shell nanoparticles. This has been attributed to the reduction in surface inhomogenities of Eu3+ surroundings by bonding to GdVO4 shell. The lifetime for D50 level increases with annealing and core/shell formation.

  4. The effect of the runoff size on the pesticide concentration in runoff water and in FOCUS streams simulated by PRZM and TOXSWA.

    Science.gov (United States)

    Adriaanse, Paulien I; Van Leerdam, Robert C; Boesten, Jos J T I

    2017-04-15

    Within the European Union the exposure of aquatic organisms to pesticides is assessed by simulations with the so-called FOCUS Surface Water Scenarios. Runoff plays an important role in these scenarios. As little is known about the effect of runoff size on the exposure, we investigated the effect of runoff size on the concentration in the runoff water and in streams simulated with the PRZM and TOXSWA models for two FOCUS runoff scenarios. For weakly sorbing pesticides (K F,oc runoff water decreased exponentially with increasing daily runoff size. The runoff size hardly affected the pesticide concentration in the runoff water of strongly sorbing pesticides (K F,oc ≥1000Lkg -1 ). For weakly sorbing pesticides the concentration in the FOCUS stream reached a maximum at runoff sizes of about 0.3 to 1mm. The concentration increased rapidly when the runoff size increased from 0 to 0.1mm and gradually decreased when runoff exceeded 1mm. For strongly sorbing pesticides the occurrence of the maximum concentration in the stream is clearly less pronounced and lies approximately between 1 and 20mm runoff. So, this work indicates that preventing small runoff events (e.g. by vegetated buffer strips) reduces exposure concentrations strongly for weakly sorbing pesticides. A simple metamodel was developed for the ratio between the concentrations in the stream and in the runoff water. This model predicted the ratios simulated by TOXSWA very well and it demonstrated that (in addition to runoff size and concentration in runoff) the size of the pesticide-free base flow and pesticide treatment ratio of the catchment determine the stream concentration to a large extent. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. CONSOLIDATION AND COMPACTION OF POWDER MIXTURES .3. BINARY-MIXTURES OF DIFFERENT PARTICLE-SIZE FRACTIONS OF DIFFERENT TYPES OF CRYSTALLINE LACTOSE

    NARCIS (Netherlands)

    RIEPMA, KA; ZUURMAN, K; BOLHUIS, GK; DEBOER, AH; LERK, CF

    1992-01-01

    Tablets were compacted from a coarse fraction (250-315 mum), a fine fraction (32-45 mum) and from binary blends of a coarse and a fine fraction of different types of crystalline lactose. The results showed differences in consolidation and compaction between the granular lactose types, i.e.,

  6. Pancreatin-EDTA treatment affects buoyancy of cells in Cohn fraction V protein density gradients without residual effect on cell size.

    Science.gov (United States)

    Sheridan, J W; Simmons, R J

    1983-12-01

    The buoyancy of suspension-grown Mastocytoma P815 X-2 cells in albumin-rich Cohn fraction V protein (CFVP) density gradients was found to be affected by prior incubation of the cells in pancreatin-EDTA salt solution. Whereas in pH 5.2 CFVP, pancreatin-EDTA treated cells behaved as if of reduced density when compared with the control 'undigested' group, in pH 7.3 CFVP they behaved as if of increased density. By contrast, pancreatin-EDTA treatment had no effect on the buoyancy of mastocytoma cells in polyvinylpyrrolidone-coated colloidal silica (PVP-CS, Percoll T.M.) density gradients of either pH 5.2 or pH 7.3. As cell size determinations failed to reveal alterations in cell size either as a direct result of pancreatin-EDTA treatment or as a combined consequence of such treatment and exposure to CFVP either with or without centrifugation, a mechanism involving a change in cell density other than during the centrifugation process itself seems unlikely. Binding studies employing 125I-CFVP, although indicating that CFVP bound to cells at 4 degrees, failed to reveal a pancreatin-EDTA treatment-related difference in the avidity of this binding. Although the mechanism of the pancreatin-EDTA-induced buoyancy shift in CFVP remains obscure, the absence of such an effect in PVP-CS suggests that the latter cell separation solution may more accurately be used to determine cell density.

  7. Limitations and Constraints of Eddy-Current Loss Models for Interior Permanent-Magnet Motors with Fractional-Slot Concentrated Windings

    Directory of Open Access Journals (Sweden)

    Hui Zhang

    2017-03-01

    Full Text Available This paper analyzes and compares models for predicting average magnet losses in interior permanent-magnet motors with fractional-slot concentrated windings due to harmonics in the armature reaction (assuming sinusoidal phase currents. Particularly, loss models adopting different formulations and solutions to the Helmholtz equation to solve for the eddy currents are compared to a simpler model relying on an assumed eddy-current distribution. Boundaries in terms of magnet dimensions and angular frequency are identified (numerically and using an identified approximate analytical expression to aid the machine designer whether the more simple loss model is applicable or not. The assumption of a uniform flux-density variation (used in the loss models is also investigated for the case of V-shaped and straight interior permanent magnets. Finally, predicted volumetric loss densities are exemplified for combinations of slot and pole numbers common in automotive applications.

  8. Simplified sample treatment for the determination of total concentrations and chemical fractionation forms of Ca, Fe, Mg and Mn in soluble coffees.

    Science.gov (United States)

    Pohl, Pawel; Stelmach, Ewelina; Szymczycha-Madeja, Anna

    2014-11-15

    A simpler, and faster than wet digestion, sample treatment was proposed prior to determination of total concentrations for selected macro- (Ca, Mg) and microelements (Fe, Mn) in soluble coffees by flame atomic absorption spectrometry. Samples were dissolved in water and acidified with HNO3. Precision was in the range 1-4% and accuracy was better than 2.5%. The method was used in analysis of 18 soluble coffees available on the Polish market. Chemical fractionation patterns for Ca, Fe, Mg and Mn in soluble coffees, as consumed, using a two-column solid-phase extraction method, determined Ca, Mg and Mn were present predominantly as cations (80-93% of total content). This suggests these elements are likely to be highly bioaccessible. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. The influence of laser pulse duration and energy on ICP-MS signal intensity, elemental fractionation, and particle size distribution in NIR fs-LA-ICP-MS

    Science.gov (United States)

    Diwakar, Prasoon K.; Harilal, Sivanandan S.; LaHaye, Nicole L.; Hassanein, Ahmed; Kulkarni, Pramod

    2015-01-01

    Laser parameters, typically wavelength, pulse width, irradiance, repetition rate, and pulse energy, are critical parameters which influence the laser ablation process and thereby influence the LA-ICP-MS signal. In recent times, femtosecond laser ablation has gained popularity owing to the reduction in fractionation related issues and improved analytical performance which can provide matrix-independent sampling. The advantage offered by fs-LA is due to shorter pulse duration of the laser as compared to the phonon relaxation time and heat diffusion time. Hence the thermal effects are minimized in fs-LA. Recently, fs-LA-ICP-MS demonstrated improved analytical performance as compared to ns-LA-ICP-MS, but detailed mechanisms and processes are still not clearly understood. Improvement of fs-LA-ICP-MS over ns-LA-ICP-MS elucidates the importance of laser pulse duration and related effects on the ablation process. In this study, we have investigated the influence of laser pulse width (40 fs to 0.3 ns) and energy on LA-ICP-MS signal intensity and repeatability using a brass sample. Experiments were performed in single spot ablation mode as well as rastering ablation mode to monitor the Cu/Zn ratio. The recorded ICP-MS signal was correlated with total particle counts generated during laser ablation as well as particle size distribution. Our results show the importance of pulse width effects in the fs regime that becomes more pronounced when moving from femtosecond to picosecond and nanosecond regimes. PMID:26664120

  10. Temporal variability of the bioaerosol background at a subway station: concentration level, size distribution, and diversity of airborne bacteria.

    Science.gov (United States)

    Dybwad, Marius; Skogan, Gunnar; Blatny, Janet Martha

    2014-01-01

    Naturally occurring bioaerosol environments may present a challenge to biological detection-identification-monitoring (BIODIM) systems aiming at rapid and reliable warning of bioterrorism incidents. One way to improve the operational performance of BIODIM systems is to increase our understanding of relevant bioaerosol backgrounds. Subway stations are enclosed public environments which may be regarded as potential bioterrorism targets. This study provides novel information concerning the temporal variability of the concentration level, size distribution, and diversity of airborne bacteria in a Norwegian subway station. Three different air samplers were used during a 72-h sampling campaign in February 2011. The results suggested that the airborne bacterial environment was stable between days and seasons, while the intraday variability was found to be substantial, although often following a consistent diurnal pattern. The bacterial levels ranged from not detected to 10(3) CFU m(-3) and generally showed increased levels during the daytime compared to the nighttime levels, as well as during rush hours compared to non-rush hours. The airborne bacterial levels showed rapid temporal variation (up to 270-fold) on some occasions, both consistent and inconsistent with the diurnal profile. Airborne bacterium-containing particles were distributed between different sizes for particles of >1.1 μm, although ∼50% were between 1.1 and 3.3 μm. Anthropogenic activities (mainly passengers) were demonstrated as major sources of airborne bacteria and predominantly contributed 1.1- to 3.3-μm bacterium-containing particles. Our findings contribute to the development of realistic testing and evaluation schemes for BIODIM equipment by providing information that may be used to simulate operational bioaerosol backgrounds during controlled aerosol chamber-based challenge tests with biological threat agents.

  11. Temporal Variability of the Bioaerosol Background at a Subway Station: Concentration Level, Size Distribution, and Diversity of Airborne Bacteria

    Science.gov (United States)

    Dybwad, Marius; Skogan, Gunnar

    2014-01-01

    Naturally occurring bioaerosol environments may present a challenge to biological detection-identification-monitoring (BIODIM) systems aiming at rapid and reliable warning of bioterrorism incidents. One way to improve the operational performance of BIODIM systems is to increase our understanding of relevant bioaerosol backgrounds. Subway stations are enclosed public environments which may be regarded as potential bioterrorism targets. This study provides novel information concerning the temporal variability of the concentration level, size distribution, and diversity of airborne bacteria in a Norwegian subway station. Three different air samplers were used during a 72-h sampling campaign in February 2011. The results suggested that the airborne bacterial environment was stable between days and seasons, while the intraday variability was found to be substantial, although often following a consistent diurnal pattern. The bacterial levels ranged from not detected to 103 CFU m−3 and generally showed increased levels during the daytime compared to the nighttime levels, as well as during rush hours compared to non-rush hours. The airborne bacterial levels showed rapid temporal variation (up to 270-fold) on some occasions, both consistent and inconsistent with the diurnal profile. Airborne bacterium-containing particles were distributed between different sizes for particles of >1.1 μm, although ∼50% were between 1.1 and 3.3 μm. Anthropogenic activities (mainly passengers) were demonstrated as major sources of airborne bacteria and predominantly contributed 1.1- to 3.3-μm bacterium-containing particles. Our findings contribute to the development of realistic testing and evaluation schemes for BIODIM equipment by providing information that may be used to simulate operational bioaerosol backgrounds during controlled aerosol chamber-based challenge tests with biological threat agents. PMID:24162566

  12. Chemical Characterization and Source Apportionment of Size Fractionated Atmospheric Aerosols, and, Evaluating Student Attitudes and Learning in Large Lecture General Chemistry Classes

    Science.gov (United States)

    Allen, Gregory Harold

    Chemical speciation and source apportionment of size fractionated atmospheric aerosols were investigated using laser desorption time-of-flight mass spectrometry (LD TOF-MS) and source apportionment was carried out using carbon-14 accelerator mass spectrometry (14C AMS). Sample collection was carried out using the Davis Rotating-drum Unit for Monitoring impact analyzer in Davis, Colfax, and Yosemite, CA. Ambient atmospheric aerosols collected during the winter of 2010/11 and 2011/12 showed a significant difference in the types of compounds found in the small and large sized particles. The difference was due to the increase number of oxidized carbon species that were found in the small particles size ranges, but not in the large particles size ranges. Overall, the ambient atmospheric aerosols collected during the winter in Davis, CA had and average fraction modern of F14C = 0.753 +/- 0.006, indicating that the majority of the size fractionated particles originated from biogenic sources. Samples collected during the King Fire in Colfax, CA were used to determine the contribution of biomass burning (wildfire) aerosols. Factor analysis was used to reduce the ions found in the LD TOF-MS analysis of the King Fire samples. The final factor analysis generated a total of four factors that explained an overall 83% of the variance in the data set. Two of the factors correlated heavily with increased smoke events during the sample period. The increased smoke events produced a large number of highly oxidized organic aerosols (OOA2) and aromatic compounds that are indicative of biomass burning organic aerosols (WBOA). The signal intensities of the factors generated in the King Fire data were investigated in samples collected in Yosemite and Davis, CA to look at the impact of biomass burning on ambient atmospheric aerosols. In both comparison sample collections the OOA2 and WBOA factors both increased during biomass burning events located near the sampling sites. The correlation

  13. Indoor human exposure to size-fractionated aerosols during the 2015 Southeast Asian smoke haze and assessment of exposure mitigation strategies

    Science.gov (United States)

    Sharma, Ruchi; Balasubramanian, Rajasekhar

    2017-11-01

    The 2015 smoke haze episode was one of the most severe and prolonged transboundary air pollution events ever seen in Southeast Asia (SEA), affecting the air quality of several countries within the region including Indonesia, Malaysia and Singapore. The 24 h mean outdoor PM2.5 (particulate matter (PM) with aerodynamic diameter ≤ 2.5 μm) concentrations ranged from 72-157 μg m-3 in Singapore during this episode, exceeding the WHO 24 h mean PM2.5 guidelines (25 μg m-3) several times over. The smoke haze episode not only affected ambient air quality, but also indoor air quality due to the migration of PM of different sizes from the outdoor to the indoor environment. Despite the frequent occurrence of smoke haze episodes over the years, their potential health impacts on indoor building occupants remain largely unknown in SEA due to the lack of systematic investigations and observational data. The current work was carried out in Singapore to assess human exposure to size-resolved PM during the 2015 smoke haze episode, and to evaluate the effectiveness of exposure mitigation measures in smoke-haze-impacted naturally ventilated indoor environments. The potential health risks associated with exposure to PM2.5 were assessed based on the concentrations of redox active particulate-bound trace elements, which are known to be harmful to human health, with and without exposure mitigation. Overall, it was observed that human health exposure to PM2.5 and its carcinogenic chemical components was reduced substantially by 62% (p health.

  14. Rare Earth Element Concentrations and Fractionation Patterns Along Groundwater Flow Paths in Two Different Aquifer Types (i.e., Sand vs. Carbonate)

    Science.gov (United States)

    Johannesson, K. H.; Tang, J.

    2003-12-01

    Groundwater samples were collected in two different types of aquifer (i.e., Carrizo Sand Aquifer, Texas and Upper Floridan carbonate Aquifer, west-central Florida) to study the concentrations, fractionation, and speciation of rare earth elements (REE) along groundwater flow paths in each aquifer. Major solutes and dissolved organic carbon (DOC) were also measured in these groundwaters. The Carrizo Sand aquifer was sampled in October 2002 and June 2003, whereas, to date, we have only sampled the Floridan once (i.e., June 2003). The data reveal no significant seasonal differences in major solute and REE concentrations for the Carrizo. In Carrizo sand aquifer, groundwaters from relatively shallow wells (i.e., less than 167 m) in the recharge zone are chiefly Ca-Na-HCO3-Cl type waters. With flow down-gradient the groundwaters shift composition to the Na-HCO3 waters. pH and alkalinity initially decrease with flow away from the recharge zone before increasing again down-gradient. DOC is generally low (0.65 mg/L) along the flow path. REE concentrations are highest in groundwaters from the recharge zone (Nd 40.5 pmol/kg), and decrease substantially with flow down-gradient reaching relatively low and stable values (Nd 4.1-8.6 pmol/kg) roughly 10 km from the recharge zone. Generally, Carrizo groundwaters exhibit HREE-enriched shale-normalized patterns. The HREE enrichments are especially strong for waters from the recharge zone [(Yb/Nd)SN =1.7-5.6], whereas down-gradient (deep) groundwaters have flatter patterns [(Yb/Nd)SN =0.7-2.5]. All groundwaters have slightly positive Eu anomalies (Eu/Eu* 0.09-0.14) and negative Ce anomalies (Ce/Ce* -0.85 - -0.07). In the Upper Floridan Aquifer, Ca, Mg, SO4, and Cl concentrations generally increase along groundwater flow path, whereas pH and alkalinity generally decrease. DOC is higher (0.64 - 2.29 mg/L) than in the Carrizo and initially increases along the flow path and then decreases down-gradient. LREE (Nd) concentrations generally

  15. The severity of late rectal and recto-sigmoid complications related to fraction size in irradiation treatment of carcinoma cervix stage III B

    International Nuclear Information System (INIS)

    Deore, S.M.; Shrivastava, S.K.; Viswanathan, P.S.; Dinshaw, K.A.; Tata Memorial Hospital, Bombay

    1991-01-01

    A retrospective analysis of late rectal and recto-sigmoid complications was carried out of the 203 patients with stage III B carcinoma of uterine cervix, treated using radiation therapy alone during January 1979 to December 1983. The patients were treated with a combination of external irradiation and single intracavitary insertion. External irradiation was randomised to one of the four different fractionation regimes having dose per fraction of 2 Gy, 3 Gy, 4 Gy and 5.4 Gy, delivering with five fractions/week, three fractions/week, two fractions/week and one fraction/week, respectively. The total doses in four different regimens were adjusted using the TDF model. There were 39 cases of late radiation induced rectal and recto-sigmoid complications. The complication rate was correlated with the dose per fraction and TDFs delivered in each regimen. The complication rate of 8.2% for 2 Gy per fraction was increased to 33.33% for 5.4 Gy per fraction. It was found that there is strong correlation (P [de

  16. Does application of the Rosiwal principle to lunar soils require that concentrations of solar-wind-implanted species be grain-size independent

    International Nuclear Information System (INIS)

    Becker, R.H.

    1977-01-01

    A reconsideration of the application of the Rosiwal Principle to lunar soils indicates a flaw in arguments put forth previously by Criswell. Specifically, by introducing a boundary condition which must exist at the lunar surface, it is shown that concentrations of solar-wind-implanted species showing a dependence on grain size may be able to develop in soils at concentration levels below those required for saturation of grain surfaces. As a result, observed grain-size-dependent concentrations of solar-wind species in lunar soils do not necessarily require the exposure time scales or solar-wind fluxes deduced from the arguments of Criswell. (Auth.)

  17. Decreased expression of indolamine 2,3-dioxygenase in childhood allergic asthma and its inverse correlation with fractional concentration of exhaled nitric oxide.

    Science.gov (United States)

    Hu, Ying; Chen, Zhiqiang; Jin, Ling; Wang, Mei; Liao, Wei

    2017-11-01

    The tryptophan metabolic pathway mediated by indolamine 2,3-dioxygenase (IDO), a tryptophan-degrading enzyme, plays an important role in controlling the development of allergic inflammation. The fractional concentration of exhaled nitric oxide (FeNO) is closely associated with the allergic state and is extensively used for the clinical evaluation of airway allergic inflammation. Clinical trials have rarely assessed the expression of IDO in childhood allergic asthma and its correlation with FeNO. To evaluate the IDO level in children with childhood allergic asthma and the relation between IDO levels and FeNO. Thirty children older than 5 years who were diagnosed the first time with allergic asthma were selected from the pediatric outpatient department. Another 30 healthy children were selected as controls. The subjects were evaluated by complete medical history, pulmonary function test results, skin prick test reaction, FeNO concentration test result, eosinophil count, and a disease severity score. Peripheral venous blood and induced sputum were obtained to measure the concentrations of IDO metabolites (ie, tryptophan and kynurenine). The IDO levels in the peripheral blood and induced sputum were significantly lower in patients with childhood allergic asthma than in children in the control group. The IDO level was negatively correlated with FeNO but was not significantly correlated with age, sex, blood eosinophil count, or disease severity scale. The expression of IDO was significantly lower in childhood allergic asthma, particularly in children with high FeNO levels. There was no significant relation between IDO levels and asthma severity. Chinese Clinical Trial Register (www.chictr.org.cn) Identifier: ChiCTR-COC-15006080. Copyright © 2017 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  18. Effect of mixture ratio, solids concentration and hydraulic retention time on the anaerobic digestion of the organic fraction of municipal solid waste.

    Science.gov (United States)

    Fongsatitkul, Prayoon; Elefsiniotis, Panagiotis; Wareham, David G

    2010-09-01

    This paper describes how the degradation of the organic fraction of municipal solid waste (OFMSW) is affected through codigestion with varying amounts of return activated sludge (RAS). Solid waste that had its inorganic fraction selectively removed was mixed with RAS in ratios of 100% OFMSW, 50% OFMSW/50% RAS, and 25% OFMSW/75% RAS. The total solids (TS) concentration was held at 8% and three anaerobic digester systems treating the mixtures were held (for the first run) at a total hydraulic retention time (HRT) of 28 days. Increasing amounts of RAS did not however improve the mixture's digestability, as indicated by little change and/or a drop in the main performance indices [including percentage volatile solids (VS) removal and specific gas production]. The optimum ratio in this research therefore appeared to be 100% OFMSW with an associated 85.1 ± 0.6% VS removal and 0.72 ± 0.01 L total gas g(- 1) VS. In the second run, the effect of increasing percentage of TS (8, 12% and 15%) at a system HRT of 28 days was observed to yield no improvement in the main performance indices (i.e. percentage VS removal and specific gas production). Finally, during the third run, variations in the total system HRT were investigated at an 8% TS, again using 100% OFMSW. Of the HRTs explored (23, 28 and 33 days), the longest HRT yielded the best performance overall, particularly in terms of specific gas production (0.77 ± 0.01 L total gas g(-1) VS).

  19. Impact of early, late, and no ST-segment resolution measured by continuous ST Holter monitoring on left ventricular ejection fraction and infarct size as determined by cardiovascular magnetic resonance imaging

    NARCIS (Netherlands)

    Haeck, Joost D. E.; Verouden, Niels J. W.; Kuijt, Wichert J.; Koch, Karel T.; Majidi, Mohamed; Hirsch, Alexander; Tijssen, Jan G. P.; Krucoff, Mitchell W.; de Winter, Robbert J.

    2011-01-01

    Background: The goal of this study is to determine the predictive value of ST-segment resolution (STR) early after percutaneous coronary intervention (PCI), late STR, and no STR for left ventricular ejection fraction (LVEF) and infarct size (IS) by cardiovascular magnetic resonance (CMR) at

  20. Asymmetric Flow Field Flow Fractionation of Aqueous C60 Nanoparticles with Size Determination by Dynamic Light Scattering and Quantification by Liquid Chromatography Atmospheric Pressure Photo-Ionization Mass Spectrometry

    Science.gov (United States)

    A size separation method was developed for aqueous C60 fullerene aggregates (aqu/C60) using asymmetric flow field flow fractionation (AF4) coupled to a dynamic light scattering detector in flow through mode. Surfactants, which are commonly used in AF4, were avoided as they may al...

  1. Aerosol measurement: the use of optical light scattering for the determination of particulate size distribution, and particulate mass, including the semi-volatile fraction.

    Science.gov (United States)

    Grimm, Hans; Eatough, Delbert J

    2009-01-01

    The GRIMM model 1.107 monitor is designed to measure particle size distribution and particulate mass based on a light scattering measurement of individual particles in the sampled air. The design and operation of the instrument are described. Protocols used to convert the measured size number distribution to a mass concentration consistent with U.S. Environmental Protection Agency protocols for measuring particulate matter (PM) less than 10 microm (PM10) and less than 2.5 microm (PM2.5) in aerodynamic diameter are described. The performance of the resulting continuous monitor has been evaluated by comparing GRIMM monitor PM2.5 measurements with results obtained by the Rupprecht and Patashnick Co. (R&P) filter dynamic measurement system (FDMS). Data were obtained during month-long studies in Rubidoux, CA, in July 2003 and in Fresno, CA, in December 2003. The results indicate that the GRIMM monitor does respond to total PM2.5 mass, including the semi-volatile components, giving results comparable to the FDMS. The data also indicate that the monitor can be used to estimate water content of the fine particles. However, if the inlet to the monitor is heated, then the instrument measures only the nonvolatile material, more comparable to results obtained with a conventional heated filter tapered element oscillating microbalance (TEOM) monitor. A recent modification of the model 180, with a Nafion dryer at the inlet, measures total PM2.5 including the nonvolatile and semi-volatile components, but excluding fine particulate water. Model 180 was in agreement with FDMS data obtained in Lindon, UT, during January through February 2007.

  2. Concentration of the genera Aspergillus, Eurotium and Penicillium in 63-μm house dust fraction as a method to predict hidden moisture damage in homes

    Directory of Open Access Journals (Sweden)

    Assadian Ojan

    2009-07-01

    Full Text Available Abstract Background Quantitative measurements of mould enrichment of indoor air or house dust might be suitable surrogates to evaluate present but hidden moisture damage. Our intent was to develop a house-dust monitoring method to detect hidden moisture damage excluding the influence of outdoor air, accumulated old dust, and dust swirled up from room surfaces. Methods Based on standardized measurement of mould spores in the 63-μm fraction of house dust yielded by carpets, the background concentrations were determined and compared to simultaneously obtained colony numbers and total spore numbers of the indoor air in 80 non-mouldy living areas during summer and winter periods. Additionally, sampling with a vacuum-cleaner or manual sieve was compared to sampling with a filter holder or sieving machine, and the evaluative power of an established two-step assessment model (lower and upper limits was compared to that of a one-step model (one limit in order to derive concentration limits for mould load in house dust. Results Comparison with existing evaluation procedures proved the developed method to be the most reliable means of evaluating hidden moisture damage, yielding the lowest false-positive results (specificity 98.7%. Background measurements and measurements in 14 mouldy rooms show that even by evaluating just the indicator genera in summer and winter, a relatively certain assessment of mould infestation is possible. Conclusion A one-step evaluation is finally possible for house dust. The house-dust evaluation method is based on analysis of the indicator genera Aspergillus, Eurotium and Penicillium spp., which depend on the total fungal count. Inclusion of further moisture indicators currently appears questionable, because of outdoor air influence and the paucity of measurements.

  3. A novel interpretation of the Fractional Inhibitory Concentration Index: The case Origanum vulgare L. and Leptospermum scoparium J. R. et G. Forst essential oils against Staphylococcus aureus strains.

    Science.gov (United States)

    Fratini, Filippo; Mancini, Simone; Turchi, Barbara; Friscia, Elisabetta; Pistelli, Luisa; Giusti, Giulia; Cerri, Domenico

    2017-01-01

    Origanum vulgare (oregano) and Leptospermum scoparium (manuka) were traditionally employed as natural remedies for infected wounds and skin injuries where Staphylococcus aureus is mainly involved. The first aim of this study was to investigate oregano and manuka essential oils (EOs) chemical compositions and evaluate their antibacterial activity (MIC, Minimum Inhibitory Concentration) against fourteen S. aureus wild strains. The second aim was to evaluate the antibacterial activities of oregano and manuka EOs mixed in different combination (FIC, Fractional Inhibitory Concentration) with an improved chequerboard technique. This allowed to avoid the usual uncertainty in the determination of MIC and FIC values and to obtain a more precise interpretation of FIC indexes (FICIs). Moreover, FICIs were discussed on the basis of a novel interpretation method to evaluate the synergistic/antagonistic effect of EOs mixtures. The most representative compounds in oregano EO were Carvacrol (65.93%), p-Cymene (9.33%) and γ-Terpinene (5.25%), while in manuka EO were Leptospermone (31.65%), cis-Calamenene (15.93%) and Flavesone (6.92%). EOs presented MIC values ranging from 1:2048 to 1:4096 v/v and FIC values ranging from 0.125 to 1. According to our interpretation, a synergistic effect (34.68%), a commutative effect (15.32%) and an indifferent effect (50.00%) and no antagonistic effect were observed. Conversely, according to two previously proposed FICI interpretation models, 1.80% synergistic effect could be observed and, respectively, 98.20% indifferent effect or 48.20% additive effect and 50.00% indifferent effect. As practical results, oregano and manuka EOs may be an effective alternative to chemotherapic drugs in staphylococcal infections and useful tools to enhance food security. Copyright © 2016 Elsevier GmbH. All rights reserved.

  4. Physically based method for measuring suspended-sediment concentration and grain size using multi-frequency arrays of acoustic-doppler profilers

    Science.gov (United States)

    Topping, David J.; Wright, Scott A.; Griffiths, Ronald; Dean, David

    2014-01-01

    As the result of a 12-year program of sediment-transport research and field testing on the Colorado River (6 stations in UT and AZ), Yampa River (2 stations in CO), Little Snake River (1 station in CO), Green River (1 station in CO and 2 stations in UT), and Rio Grande (2 stations in TX), we have developed a physically based method for measuring suspended-sediment concentration and grain size at 15-minute intervals using multifrequency arrays of acoustic-Doppler profilers. This multi-frequency method is able to achieve much higher accuracies than single-frequency acoustic methods because it allows removal of the influence of changes in grain size on acoustic backscatter. The method proceeds as follows. (1) Acoustic attenuation at each frequency is related to the concentration of silt and clay with a known grain-size distribution in a river cross section using physical samples and theory. (2) The combination of acoustic backscatter and attenuation at each frequency is uniquely related to the concentration of sand (with a known reference grain-size distribution) and the concentration of silt and clay (with a known reference grain-size distribution) in a river cross section using physical samples and theory. (3) Comparison of the suspended-sand concentrations measured at each frequency using this approach then allows theory-based calculation of the median grain size of the suspended sand and final correction of the suspended-sand concentration to compensate for the influence of changing grain size on backscatter. Although this method of measuring suspended-sediment concentration is somewhat less accurate than using conventional samplers in either the EDI or EWI methods, it is much more accurate than estimating suspended-sediment concentrations using calibrated pump measurements or single-frequency acoustics. Though the EDI and EWI methods provide the most accurate measurements of suspended-sediment concentration, these measurements are labor-intensive, expensive, and

  5. Disruption of soil aggregates by varied amounts of ultrasonic energy in fractionation of organic matter of a clay latosol : carbon, nitrogen and 13C distribution in particle-size fractions

    NARCIS (Netherlands)

    Roscoe, R.; Buurman, P.; Velthorst, E.J.

    2000-01-01

    Ultrasonic energy has been widely used to disrupt soil aggregates before fractionating soil physically when studying soil organic matter (SOM). Nevertheless, there is no consensus about the optimum energy desirable to disrupt the soil. We therefore aimed (i) to quantify the effect of varied

  6. Upper ocean carbon flux determined by the 234Th approach and sediment traps using size-fractionated POC and 234Th data from the Golf of Mexico

    International Nuclear Information System (INIS)

    Hung, Chin-Chang; Roberts, Kimberly A.; Santschi, Peter H.; Guo, Laodong

    2004-01-01

    Size-fractionated particulate 234 Th and particulate organic carbon (POC) fluxes were measured in the Gulf of Mexico during 2000 and 2001 in order to obtain a better estimation of upper ocean organic carbon export out of the euphotic zone within cold core and warm core rings, and to assess the relative merit of sediment trap and POC/ 234 Th methods. In 2000, the flux of POC measured by sediment traps at 120 m ranged from 60 to 148 mg C m -2 d -1 , while 234 Th-derived POC fluxes in large particles (>53 μm) varied from 18 to 61 mg C m -2 d -1 using the ratio of POC/ 234 Th at 120 m, and from 51 to 163 mg C m -2 d -1 using an average ratio of POC/ 234 Th for the upper 120 m water column. In 2001, the fluxes of POC measured by traps deployed at 120 m water depth ranged from 39 to 48 mg C m -2 d -1 , while the 234 Th-derived POC fluxes in large particles (>53 μm) varied from 7 to 37 mg C m -2 d -1 using a ratio of POC/ 234 Th at 120 m, and from 37 to 45 mg C m -2 d -1 using an average ratio of POC/ 234 Th within the 0-120 m interval. The results show that POC fluxes estimated by the 234 Th method using the average ratio of POC/ 234 Th within the euphotic zone are similar to those measured by sediment traps. Furthermore, the results demonstrate that the variability in POC export fluxes estimated by the 234 Th/ 238 U disequilibrium approach is strongly related to the ratio of POC/ 234 Th that is taken, and for which we have independent evidence that it may be controlled by the chemical composition of the suspended particles. The results also reveal that using POC/ 234 Th ratios in small particles may result in an estimate of the POC export flux that is considerably higher than when using POC/ 234 Th ratios in large particles (>53 μm). The POC flux calculated from ratios in large particles is, however, more comparable to the POC flux determined directly by sediment traps, but both of these estimates are much lower than that determined by using the POC/ 234 Th ratios in

  7. Size fraction effect on phthalate esters accumulation, bioaccessibility and in vitro cytotoxicity of indoor/outdoor dust, and risk assessment of human exposure.

    Science.gov (United States)

    Wang, Wei; Wu, Fu-Yong; Huang, Min-Juan; Kang, Yuan; Cheung, Kwai Chung; Wong, Ming Hung

    2013-10-15

    Indoor and outdoor dusts from two urban centers in the Pearl River Delta, China, were analyzed and phthalate esters varied from 4.95 to 2,220 μg g(-1) in indoor dust, significantly higher than outdoor dust (1.70-869 μg g(-1)). Di-2-ethylhexyl phthalate (DEHP) was the dominant phthalate found and the highest distribution factor (DF) (1.56 ± 0.41) was noted in the human T cell lymphoblast leukemic cell line (CCRF-CEM) indicated by Lethal Concentration 50 (LC50) decreased with particle size. The power model was found as a better fit for explaining the relationship between LC50 and phthalates (R(2)=0.46, passessment indicated that indoor dust ingestion accounted for the major source for DEHP exposure (81.4-96.4% of non-dietary exposure and 36.5% of total exposure), especially for toddlers. The cancer risks associated with DEHP via home dust were high (10(-6)-10(-4)), with 10% of houses estimated with unacceptable risks (>10(-4)). After corrected with the bioaccessibility of phthalates, the cancer risks of dust exposure were moderate (10(-7)-10(-5)). Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Determining the size and concentration dependence of gold nanoparticles in vitro cytotoxicity (IC{sub 50}) test using WST-1 assay

    Energy Technology Data Exchange (ETDEWEB)

    Rosli, Nur Shafawati binti; Rahman, Azhar Abdul [School of Physics, Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); Aziz, Azlan Abdul [School of Physics, Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); Shamsuddin, Shaharum [Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); School of Health Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

    2015-04-24

    Gold nanoparticles (AuNPs) received a great deal of attention for biomedical applications, especially in diagnostic imaging and therapeutics. Even though AuNPs have potential benefits in biomedical applications, the impact of AuNPs on human and environmental health still remains unclear. The use of AuNPs which is a high-atomic-number materials, provide advantages in terms of radiation dose enhancement. However, before this can become a clinical reality, cytotoxicity of the AuNPs has to be carefully evaluated. Cytotoxicity test is a rapid, standardized test that is very sensitive to determine whether the nanoparticles produced are harmful or benign on cellular components. In this work the size and concentration dependence of AuNPs cytotoxicity in breast cancer cell lines (MCF-7) are tested by using WST-1 assay. The sizes of AuNPs tested were 13 nm, 50 nm, and 70 nm. The cells were seeded in the 96-well plate and were treated with different concentrations of AuNPs by serial dilution for each size of AuNPs. The high concentration of AuNPs exhibit lower cell viability compared to low concentration of AuNPs. We quantified the toxicity of AuNPs in MCF-7 cell lines by determining the IC{sub 50} values in WST-1 assays. The IC{sub 50} values (inhibitory concentrations that effected 50% growth inhibition) of 50 nm AuNPs is lower than 13 nm and 70 nm AuNPs. Mean that, 50nm AuNPs are more toxic to the MCF-7 cells compared to smaller and larger sizes AuNPs. The presented results clearly indicate that the cytotoxicity of AuNPs depend not only on the concentration, but also the size of the nanoparticles.

  9. Preconception and prenatal urinary concentrations of phenols and birth size of singleton infants born to mothers and fathers from the Environment and Reproductive Health (EARTH) study.

    Science.gov (United States)

    Messerlian, Carmen; Mustieles, Vicente; Minguez-Alarcon, Lidia; Ford, Jennifer B; Calafat, Antonia M; Souter, Irene; Williams, Paige L; Hauser, Russ

    2018-05-01

    Although pregnancy concentrations of some phenols have been associated with infant size at birth, there is limited data on the effect of preconception exposure. We aimed to examine paternal and maternal preconception and maternal prenatal urinary phenol concentrations in relation to birth weight and head circumference. We evaluated 346 singletons born to 346 mothers and 184 fathers (184 couples) from a prospective preconception cohort of subfertile couples from the Environment and Reproductive Health (EARTH) Study in Boston, USA. We used multiple urine samples collected before the index pregnancy in both men and women to estimate mean preconception urinary benzophenone-3, triclosan, butylparaben, propylparaben, methylparaben, or ethylparaben concentrations. We also estimated mean maternal prenatal urinary phenol concentrations by averaging trimester-specific urine samples. Birth weight and head circumference were abstracted from delivery records. We estimated the association of natural log-phenol concentrations with birth outcomes using multivariable linear regression models, adjusting for known confounders. In adjusted models, each log-unit increase in paternal preconception benzophenone-3 concentration was associated with a 137 g increase in birth weight (95% CI: 60, 214). Additional adjustment for prenatal benzophenone-3 concentration strengthened this association. None of the maternal preconception phenol concentrations were associated with birth weight. However, maternal prenatal triclosan concentrations were associated with a 38 g decrease in birth weight (95% CI: -76, 0). Few associations were observed between phenols and head circumference except for a decrease of 0.27 cm (95% CI: -54, 0) in relation to maternal preconception methylparaben concentration. Although our findings should be interpreted in light of inherent study limitations, these results suggest potential evidence of associations between some paternal or maternal phenol concentrations and

  10. The effect of ultrasonic pretreatment on biogas generation yield from organic fraction of municipal solid waste under medium solids concentration circumstance

    International Nuclear Information System (INIS)

    Rasapoor, Mazdak; Ajabshirchi, Yahya; Adl, Mehrdad; Abdi, Reza; Gharibi, Arash

    2016-01-01

    Highlights: • Ultrasonic pretreatment improved biogas yields at lower TS content samples. • Time of ultrasonication was significantly effective on maximum biogas yields. • Ultrasonic pretreatment can cause the release of TVFA content before digestion. • Specific energy between 5000 kJ/kg TS and 10,000 kJ/kg TS improved biogas yields. - Abstract: Hydrolysis is the most rate limiting step in almost all anaerobic digestion systems. To tackle long time duration, ultrasonic pretreatment proved that it can effectively improve biogas yield efficiency by effecting on soluble particles. In this study, the effect of three different ultrasonic power densities (0.2 W/mL, 0.4 W/mL and 0.6 W/mL) at three different times (10 min, 20 min and 30 min) on biogas yield of organic fraction of municipal solid waste (OFMSW) at three different total solid content (6%, 8% and 10%) were analyzed. Results showed significant (p < 0.01) effect of both sonication density and time of sonication on biogas final yield and biogas yield after 72 h digestion with the 6% TS content. Parameters like specific energy input and total volatile fatty acid (TVFA) content were also evaluated to find the best sonication treatments for OFMSW. For lower TS contents (6% and 8%), sonication treatment significantly (p < 0.01) increased TVFA concentration before digesting. It is also proved that specific energy input between 5000 kJ/kg TS and 10,000 kJ/kg TS can effectively increase the biogas yields, especially for 6% TS content, and caused maximum biogas yield produced after 72 h of digestion.

  11. Solid state CP/MAS 13C n.m.r. analysis of particle size and density fractions of soil incubated with uniformly labelled 13C-glucose

    International Nuclear Information System (INIS)

    Baldock, J.A.; Oades, J.M.

    1990-01-01

    A soil incubated for 34 days in the absence (control) and presence (treated) of uniformly labelled 13 C-glucose was dispersed using an ultrasonic probe and fractionated by sedimentation in water and a polytungstate solution of density 2.0 Mg m -3 . Solid state CP/MAS 13 C n.m.r. (cross polarization/magic angle spinning 13 C nuclear magnetic resonance) spectroscopy was used to characterize the chemical structure of the native soil organic carbon and the residual substrate carbon in the fractions of the control and treated soils. To obtain quantitative results it was essential to determine the spin lattice relaxation time in a rotating frame of the individual carbon types in the spectra as the relaxation behaviour of the native organic material in the clay fraction was different from that of the residual substrate carbon. The residual substrate carbon was found to accumulate in predominantly alkyl and O-alkyl structures in both fractions. However, significant amounts of acetal and carboxyl carbon were also observed in the clay fraction. Little if any aromatic or phenolic carbon was synthesized by the soil microorganisms utilizing substrate carbon. Dipolar dephasing CP/MAS 13 C n.m.r. experiments were also performed and allowed the proportion of each type of carbon which was protonated and nonprotonated to be estimated. Essentially all of the O-alkyl and acetal carbon, 25-40% of the aromatic carbon and 66-80% of the alkyl carbon was protonated in the fractions isolated from the treated soil. 24 refs., 4 figs., 2 tabs

  12. Tree age, fruit size and storage conditions affect levels of ascorbic acid, total phenolic concentrations and total antioxidant activity of 'Kinnow' mandarin juice.

    Science.gov (United States)

    Khalid, Samina; Malik, Aman U; Khan, Ahmad S; Shahid, Muhammad; Shafique, Muhammad

    2016-03-15

    Bioactive compounds (ascorbic acid, total phenolics and total antioxidants) are important constituents of citrus fruit juice; however, information with regard to their concentrations and changes in relation to tree age and storage conditions is limited. 'Kinnow' (Citrus nobilis Lour × Citrus deliciosa Tenora) mandarin juice from fruit of three tree ages (6, 18 and 35 years old) and fruit sizes (large, medium and small) were examined for their bioactive compounds during 7 days under ambient storage conditions (20 ± 2 °C and 60-65% relative humidity (RH)) and during 60 days under cold storage (4 ± 1 °C and 75-80% RH) conditions. Under ambient conditions, a reduction in total phenolic concentrations (TPC) and in total antioxidant activity (TAA) was found for the juice from all tree ages and fruit sizes. Overall, fruit from 18-year-old trees had higher mean TPC (95.86 µg mL(-1) ) and TAA (93.68 mg L(-1) ), as compared to 6 and 35-year-old trees. Likewise, in cold storage, TAA decreased in all fruit size groups from 18 and 35-year-old trees. In all tree age and fruit size groups, TPC decreased initially during 15 days of cold storage and then increased gradually with increase in storage duration. Ascorbic acid concentrations showed an increasing trend in all fruit size groups from 35-year-old trees. Overall, during cold storage, fruit from 18-year-old trees maintained higher mean ascorbic acid (33.05 mg 100 mL(-1) ) concentrations, whereas fruit from 6-year-old trees had higher TAA (153.1 mg L(-1) ) and TPC (115.1 µg mL(-1) ). Large-sized fruit had higher ascorbic acid (32.08 mg 100 mL(-1) ) concentrations and TAA (157.5 mg L(-1) ). Fruit from 18-year-old trees maintained higher TPC and TAA under ambient storage conditions, whereas fruit from 6-year-old trees maintained higher TPC and TAA during cold storage. Small-sized fruit had higher TPC after ambient temperature storage, whereas large fruit size showed higher ascorbic acid concentrations and TAA after cold

  13. Environmentally-relevant concentrations of atrazine induce non-monotonic acceleration of developmental rate and increased size at metamorphosis in Rhinella arenarum tadpoles.

    Science.gov (United States)

    Brodeur, Julie C; Sassone, Alina; Hermida, Gladys N; Codugnello, Nadia

    2013-06-01

    Despite of the various studies reporting on the subject, anticipating the impacts of the widely-used herbicide atrazine on anuran tadpoles metamorphosis remains complex as increases or decreases of larval period duration are almost as frequently reported as an absence of effect. The aim of the present study was to examine the effects of environmentally-relevant concentrations of atrazine (0.1, 1, 10, 100, and 1000μg/L) on the timings of metamorphosis and body size at metamorphosis in the common South American toad, Rhinella arenarum (Anura: bufonidae). None of the atrazine concentrations tested significantly altered survival. Low atrazine concentrations in the range of 1-100μg/L were found to accelerate developmental rate in a non-monotonic U-shaped concentration-response relationship. This observed acceleration of the metamorphic process occurred entirely between stages 25 and 39; treated tadpoles proceeding through metamorphosis as control animals beyond this point. Together with proceeding through metamorphosis at a faster rate, tadpoles exposed to atrazine concentrations in the range of 1-100μg/L furthermore transformed into significantly larger metamorphs than controls, the concentration-response curve taking the form of an inverted U in this case. The no observed effect concentration (NOEC) was 0.1μg atrazine/L for both size at metamorphosis and timings of metamorphosis. Tadpoles exposed to 100μg/L 17β-estradiol presented the exact same alterations of developmental rate and body size as those treated with 1, 10 and 100μg/L of atrazine. Elements of the experimental design that facilitated the detection of alterations of metamorphosis at low concentrations of atrazine are discussed, together with the ecological significance of those findings. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Optimal voxel size for measuring global gray and white matter proton metabolite concentrations using chemical shift imaging

    DEFF Research Database (Denmark)

    Hanson, Lars Peter Grüner; Adalsteinsson, E; Pfefferbaum, A

    2000-01-01

    Quantification of gray and white matter levels of spectroscopically visible metabolites can provide important insights into brain development and pathological conditions. Chemical shift imaging offers a gain in efficiency for estimation of global gray and white matter metabolite concentrations co...

  15. Hollow-fiber flow field-flow fractionation and multi-angle light scattering investigation of the size, shape and metal-release of silver nanoparticles in aqueous medium for nano-risk assessment.

    Science.gov (United States)

    Marassi, Valentina; Casolari, Sonia; Roda, Barbara; Zattoni, Andrea; Reschiglian, Pierluigi; Panzavolta, Silvia; Tofail, Syed A M; Ortelli, Simona; Delpivo, Camilla; Blosi, Magda; Costa, Anna Luisa

    2015-03-15

    Due to the increased use of silver nanoparticles in industrial scale manufacturing, consumer products and nanomedicine reliable measurements of properties such as the size, shape and distribution of these nano particles in aqueous medium is critical. These properties indeed affect both functional properties and biological impacts especially in quantifying associated risks and identifying suitable risk-mediation strategies. The feasibility of on-line coupling of a fractionation technique such as hollow-fiber flow field flow fractionation (HF5) with a light scattering technique such as MALS (multi-angle light scattering) is investigated here for this purpose. Data obtained from such a fractionation technique and its combination thereof with MALS have been compared with those from more conventional but often complementary techniques e.g. transmission electron microscopy, dynamic light scattering, atomic absorption spectroscopy, and X-ray fluorescence. The combination of fractionation and multi angle light scattering techniques have been found to offer an ideal, hyphenated methodology for a simultaneous size-separation and characterization of silver nanoparticles. The hydrodynamic radii determined by fractionation techniques can be conveniently correlated to the mean average diameters determined by multi angle light scattering and reliable information on particle morphology in aqueous dispersion has been obtained. The ability to separate silver (Ag(+)) ions from silver nanoparticles (AgNPs) via membrane filtration during size analysis is an added advantage in obtaining quantitative insights to its risk potential. Most importantly, the methodology developed in this article can potentially be extended to similar characterization of metal-based nanoparticles when studying their functional effectiveness and hazard potential. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Cortisol and prolactin concentrations during repeated blood sample collection from freely moving, mouse-sized mammals (Phodopus spp.).

    Science.gov (United States)

    Reburn, C J; Wynne-Edwards, K E

    2000-04-01

    Validation of a method for obtaining blood samples that does not change cortisol or prolactin concentrations yet allows serial blood samples to be collected from animals under anesthesia, without prior handling, from freely interacting social groups of small mammals. Results from five experiments are reported. Male dwarf hamsters (Phodopus spp.) were housed in modified home cages under continuous flow of compressed air that could be switched to isoflurane in O2 vehicle without approaching the cages. Dwarf hamsters respond to manual restraint with behavioral distress and increase in the concentration of the dominant glucocorticoid, cortisol, and decrease in prolactin concentration. Both effects are evident within one minute. In contrast, when this new method was used, neither cortisol nor prolactin changed in response to repeated sample collection (up to 8 successive samples at 2 hour intervals), prolonged isoflurane exposure, or substantial blood volume reduction (30%). Prolactin concentration was suppressed and cortisol concentration was increased in response to stimuli from other hamsters tested without anesthesia. Suppression of prolactin concentration was graded in response to the degree of stress and equaled the pharmacologic reduction caused by bromocryptine mesylate (50 microg of CB154 x 3 days). The technique is superior to alternatives for studies of behavioral endocrinology of freely interacting small mammals.

  17. Effect of moisture, charge size, and chlorine concentration on PCDD/F emissions from simulated open burning of forest biomass

    Science.gov (United States)

    Loblolly pine (Pinus taeda) was combusted at different charge sizes, fuel moisture, and chlorine content to determine the effect on emissions of polychlorinated dibenzo-p-dioxins and polychlorinated diberizofurans (PCDDslFs) as well as co-pollutants CO, PM, and total hydrocarbons...

  18. Size Determination of Aqueous C60 by Asymmetric Flow Field-Flow Fractionation (AF4) and in-Line Dynamic Light Scattering

    Science.gov (United States)

    To date, studies on the environmental behaviour of aggregated aqueous fullerene nanomaterials have used the entire size distribution of fullerene aggregates and do not distinguish between different aggregate size classes. This is a direct result of the lack of analytical methods ...

  19. Effect of H3PO4 Concentration and Particle Size of the Eggshell Used in Laying Hens Fed on Bone and Blood

    Directory of Open Access Journals (Sweden)

    S. Kismiati

    2013-06-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 The objective of this research was to evaluate the effect of H3 PO4 concentrations and particle size of eggshell used in the feed of laying hens on bone and blood profiles. Ninety-six laying hens (Isa Brown strain age 25 weeks were kept in individual battery cage and divided into 8 groups randomly. Group 1 was fed using eggshell with out H3PO4 and particle size of <1 mm (feed 1 , group 2 was fed using eggshell that has been soaked in H3PO4 3% and particle size of <1 mm (feed 2, group 3 were fed using eggshell that has been soaked in H3PO4 4% and particle size of <1 mm (feed 3, group 4 was fed using eggshell that has been soaked in H3PO4 5% and particle size of <1 mm (feed 4, group 5 was fed using eggshell that has been soaked in H3PO4 and particle size of <3 mm (feed 5 , group of 6 was fed using eggshell that has been soaked in H3PO4 3% and particle size of <3 mm (feed 6, group 7 was fed using eggshell that has been soaked in H3PO4 4 % and particle size of <3 mm (feed 7 and a group of 8 was fed using eggshell that has been soaked in H3PO4 5% and particle size of <3 mm (feed 8. A Completely Randomized Design patterns factorial 4 x 2 x 3 was used in this research. Result of this research showed that had no interaction effect (P>0.05 between the H3PO4 concentration and particle size of eggshell on weight, volume, diameter of tibia bone and calcium and phosphorus content of the blood. The concentration of H3PO4 or particles size also had no effect (P>0.05 on all variables. Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size

  20. The influence of particle size and AgNO3 concentration in the ionic exchange process on the fungicidal action of antimicrobial glass

    International Nuclear Information System (INIS)

    Mendes, E.; Piletti, R.; Barichello, T.; Oliveira, C.M.; Kniess, C.T.; Angioletto, E.; Riella, H.G.

    2012-01-01

    Antimicrobial materials have long been used as an effective means of reducing the risks posed to humans by fungi, bacteria and other microorganisms. These materials are essential in environments where cleanliness, comfort and hygiene are the predominate concerns. This work presents preliminary results for the development of a fungicidal vitreous material that is produced by the incorporation of a silver ionic specimen through ionic exchange reactions. Silver ions were incorporated into powdered glass via ionic exchange in an ionic medium containing silver species with different concentrations of AgNO 3 . The fungicidal efficiency of the samples was studied as a function of the AgNO 3 concentration and the particle size of the glass using the agar diffusion test for the microbiological analysis of the fungus species Candida albicans. The samples were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The experimental results showed that the fungicidal effect was dependent on the AgNO 3 concentration in the ionic exchange medium but was not dependent on the particle size of the glass. - Highlights: ► The fungicidal powder glass presents high potential for application as polymeric additive and others application in the medical area. ► The fungicidal effect was dependent on AgNO3 concentration, but was not dependent on the particle size of the glass. ► The XRD results show that the ionic exchange process promotes the formation of silver crystalline phases with cubic cells.

  1. Fractionation And Distribution Of Heavy Metals In street Dust In Amman, Jordan

    International Nuclear Information System (INIS)

    Jaradat, Q.

    2002-01-01

    Different types of street dust: major streets, minor streets, gas stations, traffic lights and car parks in Amman were subjected to size-fractionation into three sizes: 500-125μm , 125-53μm, and <53μm. Sequential extraction was also performed on the non-fractionated samples using Tessier procedure. The sequentially extracted and the fractionated samples were analyzed for Pb, Cd, Zn and Mn using flame atomic absorption. The silt fraction ( <53μm particles ) contains the highest concentrations of all elements in most types of street dust samples followed by the fine fraction ( 125-53μm particles). From the sequential extraction data, the highest concentrations of heavy metals were : Pb, Cd, Zn and in Fe-Mn oxide fraction, and Cu in the organic fraction. (author). 29 refs., 2 figs., 4 tabs

  2. Effect of particle size and concentration on the mechanical properties of polyester/date palm seed particulate composites

    Directory of Open Access Journals (Sweden)

    Alewo Opuada AMEH

    2015-05-01

    Full Text Available The use of cellulosic materials as reinforcement in composites can greatly enhance their properties. The thrust of this study was to investigate the effect of date palm seed particle on the properties of reinforced polyester. Unsaturated polyester resin was reinforced with date palm seed particles of 0.5, 2.0 and 2.8mm particle sizes using variable particle loadings of 5, 10, 15, 20 and 25wt%. The composites obtained were subjected to various types of mechanical and physical tests in order to assess their performance. The optimum tensile strength of 16.7619N/mm2 and elastic modulus of 343.8N/mm2 were attained at 15wt% and 10wt% loading (using 0.5mm particles respectively and percent water absorption was found to be least for 0.5mm particle size. The hardness was enhanced to the maximum of 74 HRF (Rockwell Hardness Factor by 2mm particle size at 25wt% loading. Pure unsaturated polyester resin recorded tensile strength of 17.5959N/mm2, elastic modulus of 316.7N/mm2 and hardness of 33.5 HRF. The results indicated that the use of date palm seed particles as reinforcement can enhance the properties of polyester composites.

  3. Relationship of bifenthrin sediment concentrations to grain size and total organic carbon in California waterbodies: implications for ecological risk.

    Science.gov (United States)

    Hall, Lenwood W; Anderson, Ronald D

    2014-12-01

    A summary analysis of data sets from six California waterbodies was conducted to determine the relationship of bifenthrin sediment concentrations to: % sand/gravel; % silt; % clay; % silt/clay and % total organic carbon (TOC). The relationship of TOC to % sand/gravel, % silt, % clay, and % silt/clay was also analyzed. Statistically significant and meaningful direct relationships were reported between bifenthrin and % TOC, % silt, % clay and % silt/clay while a significant and meaningful inverse relationship was reported between bifenthrin and % sand/gravel. A significant and meaningful inverse relationship was reported between % TOC and % sand/gravel, while a significant and meaningful direct relationship was reported between % TOC and % silt, % clay and % silt/clay. Significant bifenthrin sediment concentrations would not be expected in non-depositional (sand/gravel) areas which have been reported to be dominant in various streams in California's Central Valley and are also the preferred habitat for many benthic macroinvertebrate taxa.

  4. Suspended particulate matter in New York City: element concentrations as a function of particle size and elevation above street

    Inter