Browsing by Author "Zhang, H"

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    Quantifying the influences of atmospheric stability on air pollution in Lanzhou, China, using a radon-based stability monitor
    (Elsevier, 2015-04) Chambers, SD; Wang, F; Williams, AG; Xiaodong, D; Zhang, H; Lonati, G; Crawford, J; Griffiths, AD; Ianniello, A; Allegrini, I
    Commercially-available “stability monitors” based on in situ atmospheric radon progeny measurements remain underutilised as a tool for urban pollution studies, due in part to difficulties experienced in relating their standard output directly to the atmospheric mixing state in a consistent manner. The main confounding factor has been a lack of attention to the fact that the observed near-surface atmospheric radon concentration includes large synoptic and fetch-related components in addition to the local stability influence. Here, a technique recently developed for stability classification using a research-quality dual-flow-loop two-filter radon detector is adapted for use with a commercially-available radon-based stability monitor. Performance of the classification scheme is then tested in Lanzhou, China, a topographically-complex region renowned for low mean annual wind speeds (0.8 m s−1) and winter stagnation episodes. Based on an 11-month composite, a factor of seven difference is estimated between peak NOx concentrations in the city's industrial region and a rural background location under stable conditions. The radon-based scheme is evaluated against the Pasquil-Gifford “radiation” (PGR) scheme, and assigns pollutant concentrations more consistently between defined atmospheric stability states than the PGR scheme. Furthermore, the PGR scheme consistently underestimates all peak pollutant concentrations under stable conditions compared with the radon-based scheme, in some cases (e.g. CO in the industrial region) by 25%. © 2015, Elsevier Ltd.
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    Synthesis, structure and conductivity of BaIn0.8Mn0.2O3 − δ
    (Elsevier, 2014-04-01) Yang, C; Shu, T; Zhang, H; Dong, J; Zhiwen, S; Xiong, C; Sihai, Y; Guobao, L; Liao, F; Lin, J
    Green BaIn0.80Mn0.20O2.70 (S1) has been synthesized by solid-state reaction under high temperature, and black BaIn0.80Mn0.20O2.60 (RS1) is obtained by treating S1 under vacuum at 500 °C. They were characterized by powder X-ray and neutron diffraction, selected area electron diffraction, magnetic measurement, and impedance spectrum. S1 and RS1 crystallize in Cmcm (a = 5.9722(3), b = 5.9664(3), c = 8.4511(4) Å) and P21/c (a = 5.9328(7), b = 5.9445(11), c = 16.8154(14) Å, β = 90.02(2)°), respectively. Oxide ion vacancies are confirmed to exist in S1 and RS1 by the neutron diffraction data. © 2014, Elsevier B.V.