43 research outputs found

    Unburned carbon measurement in fly ash using laser-induced breakdown spectroscopy with short nanosecond pulse width laser

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    The unburned carbon in fly ash is one of the important factors for the boiler combustion condition. Controlling the unburned carbon in fly ash is beneficial for fly ash recycle and to improve the combustion efficiency of the coal. Laser-induced breakdown spectroscopy (LIBS) technology has been applied to measure the fly ash contents due to its merits of non-contact, fast response, high sensitivity, and real-time measurement. In this study, experimental measurements have been adopted for fly ash flows with the surrounding gases of N2 and CO2, while the CO2 concentration varified to evaluate the CO2 effect on the unburned carbon signal from fly ash powder. Two kinds of pulse width lasers, 6ns and 1ns, were separately adopted to compare the influence of laser pulse width. Results showed that compared with 6ns pulse width laser, plasma temperature was lower and had less dependence on delay time when using 1ns pulse width laser, and spectra had more stable background. By using 1ns pulse width laser, the emission signal from surrounding CO2 also decreased because of the less surrounding gas breakdown. The solid powder breakdown signals also became more stable when using 1ns pulse width laser. So it is demonstrated that 1ns pulse width laser has the merits for fly ash flow measurement using LIBS

    Dietary exposure to pesticide residues and associated health risks in infants and young children – Results of the French infant total diet study

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    A total diet study (TDS) was undertaken to estimate the chronic dietary exposure to pesticide residues and health risks for the French infants and young children below 3 years old. As a whole, 516 pesticides and metabolites were analysed in 309 food composite samples including 219 manufactured baby foods and 90 common foods, which cover 97% of infants and young children's diet. These composite samples were prepared using 5,484 food products purchased during all seasons from 2011 to 2012 and processed as consumed. Pesticide residues were detected in 67% of the samples and quantified in 27% of the baby food samples and in 60% of the common foods. Seventy-eight different pesticides were detected and 37 of these quantified at levels ranging from 0.02 to 594 µg/kg. The most frequently detected pesticides (greater than 5% samples) were (1) the fungicides 2-phenylphenol, azoxystrobin, boscalid, captan and its metabolite tetrahydrophthalimide, carbendazim, cyprodinil, difenoconazole, dodine, imazalil, metalaxyl, tebuconazole, thiabendazole, (2) the insecticides acetamiprid, pirimiphos-methyl and thiacloprid, (3) the herbicide metribuzin and (4) the synergist piperonyl butoxide. Dietary intakes were estimated for each of the 705 individuals studied and for 431 pesticides incl. 281 with a toxicological reference value (TRV). In the lower-bound scenario, which tends to underestimate the exposure, the TRV were never exceeded. In the upper-bound scenario that overestimates exposure, the estimated intakes exceeded the TRV for dieldrin and lindane (two persistent organic pollutants) and propylene thiourea, a metabolite of propineb. For these three substances, more sensitive analyses are needed to refine the assessment. For 17 other detected and/or prioritised pesticides, the risk could not be characterised due to the lack of a valid TRV, of certain food analyses or the absence of analytical standards for their metabolites. Keywords: Food safety, Infants and young children, Pesticide residues, Total diet study, Exposure assessment, Risk characterizatio

    Determination of Formetanate Hydrochloride in Strawberries

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    Spatial and Temporal Variations in the Ecological Efficiency and Ecosystem Service Value of Agricultural Land in China

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    In-depth analysis of spatial and temporal variations in the ecological efficiency of agricultural land has important theoretical and practical significance in achieving the efficient utilization of agricultural land, the coordinated development of natural resources and the environment, and the formulation of sustainable agricultural development policies. By including carbon emissions and pollution as undesired output indicators of agricultural land use, and introducing ecological service values as output indicators, an SBM-Undesirable model which can not only avoid the deviation caused by the difference of radial and angular selection, but also reflect the essence of efficiency evaluation, was used to estimate the ecological efficiency of agricultural land in 30 provinces, municipalities and autonomous regions of China from 2004 to 2017. Spatial and temporal differences were then analyzed. The results show that (1) The ecological efficiency of agricultural land in China decreased overall from 2004 to 2017. (2) The eco-efficiency of agricultural land was highest in the eastern provinces, lowest in the central provinces, and moderate in the western provinces. (3) Among the input indicators, the input redundancy rates of agricultural land, chemical fertilizer input and agricultural film input were too high. (4) China’s agricultural land use has not evolved towards harmonious development of the environment and economy. Due to the excessive use of chemical fertilizers, agricultural films and other factors that cause pollution, there has been a one-sided increase in the economic output of agricultural land, and improvements in ecological value have been inhibited. Based on the research results, feasible suggestions are put forward to improve the ecological efficiency of agricultural land in China

    Spatial and Temporal Variations in the Ecological Efficiency and Ecosystem Service Value of Agricultural Land in China

    No full text
    In-depth analysis of spatial and temporal variations in the ecological efficiency of agricultural land has important theoretical and practical significance in achieving the efficient utilization of agricultural land, the coordinated development of natural resources and the environment, and the formulation of sustainable agricultural development policies. By including carbon emissions and pollution as undesired output indicators of agricultural land use, and introducing ecological service values as output indicators, an SBM-Undesirable model which can not only avoid the deviation caused by the difference of radial and angular selection, but also reflect the essence of efficiency evaluation, was used to estimate the ecological efficiency of agricultural land in 30 provinces, municipalities and autonomous regions of China from 2004 to 2017. Spatial and temporal differences were then analyzed. The results show that (1) The ecological efficiency of agricultural land in China decreased overall from 2004 to 2017. (2) The eco-efficiency of agricultural land was highest in the eastern provinces, lowest in the central provinces, and moderate in the western provinces. (3) Among the input indicators, the input redundancy rates of agricultural land, chemical fertilizer input and agricultural film input were too high. (4) China’s agricultural land use has not evolved towards harmonious development of the environment and economy. Due to the excessive use of chemical fertilizers, agricultural films and other factors that cause pollution, there has been a one-sided increase in the economic output of agricultural land, and improvements in ecological value have been inhibited. Based on the research results, feasible suggestions are put forward to improve the ecological efficiency of agricultural land in China

    Toughened High-Flow Polypropylene with Polyolefin-Based Elastomers

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    Polyolefin is the most widely used and versatile commodity polymer. In this work, three types of polyolefin-based elastomers (PBEs) were adopted to toughen a high-flow polypropylene to improve its overall performance. The chain microstructures of these PBEs, including ethylene/1-octene (E/O) random copolymer from Dow Chemical′s polyolefin elastomer (POE), olefin block copolymers (OBCs) of E/O from Dow, and ethylene/propylene random copolymer from ExxonMobil’s propylene-based elastomer, were elucidated by GPC, 13C NMR, TREF, and DSC techniques. The mechanical, thermal and optical properties, and morphology analysis of the PP/PBE blends were also studied to investigate the toughening mechanism of these PBEs. The results showed that all three types of PBEs can effectively improve the Izod impact strength of the PP/PBE blends by the addition of the rubber compositions, at the cost of the stiffness. PBE-1 and PBE-2 were found to have a great stiffness–toughness balance with about 1700 MPa of flexural modulus, about 110 °C of HDT and 3.6 kJ/m2 of impact strength on the prepared PP/PBE blends by forming separated rubber phase and refined spherulite crystals. As a result, the OBC with alternating hard and soft segments could achieve a similar toughening effect as the E/P random copolymer. Surprisingly, no obvious rubber phase separation was observed in the PP/PBE-4 blend, which might be due to the good compatibility of the E/P random chains with the isotactic PP; therefore, the PP/PBE blend obtains great toughness performance and optical transparency with the highest Izod impact strength of 4.2 kJ/m2 and excellent transparency
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