Browsing by Author "Tao, Jun"

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Biomass burning tracers in rural and urban ultrafine particles in Xi'an, China
(2017-07-01)
Zhu, Chong-Shu
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Cao, Jun-Ji
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Tsai, Chuen-Jinn
;
Zhang, Zhi-Sheng
;
Tao, Jun
To investigate the impact of biomass burning emissions on ultrafine particles (PM0.133: particulate matter with an aerodynamic diameter less than 0.133 mu m), biomass burning tracers (including levoglucosan, mannonsan and K+) were measured at a rural and an urban sites in Xi'an during winter heating period. The average levoglucosan concentrations of rural and urban PM0.133 were 0.93 +/- 0.32 mu g m(-3) and 0.29 +/- 0.14 mg m(-3), respectively. Comparable PM0.133 mannosan concentrations were observed in rural samples (0.16 +/- 0.26 mu g m(-3)) and urban samples (0.17 +/- 0.10 mu g m(-3)). Higher correlation between levoglucosan and K+ was obtained for urban samples (R = 0.86) than that for rural samples (R = 0.72). The levoglucosan to K+ ratio was found to be higher for rural samples (0.77 +/- 0.39) compared to that for urban samples (0.32 +/- 0.14). Levoglucosan to mannosan ratios averaged 7.86 and 2.83 for rural and urban samples, respectively. It can be concluded that the major source of rural biomass burning was the combustion of crop residuals and softwood. The contributions of biomass burning to OC ranged from 19% to 32%, with an average of 24% for rural samples. The results provide a better understanding on the rural and urban magnitude of levoglucosan and contributions of biomass burning in Xi'an. (C) 2017 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved.
TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating
(2017-11-01)
Hang, Tian
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Chen, Hui-Jiuan
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Xiao, Shuai
;
Yang, Chengduan
;
Chen, Meiwan
Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano-and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials.