| 1. |
- Wang, Pu, et al.
(författare)
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Altitude dependence of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in surface soil from Tibetan Plateau, China
- 2009
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 76:11, s. 1498-1504
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Tidskriftsartikel (refereegranskat)abstract
- Remote mountain areas besides high latitude regions are beginning to receive increased attention in studying the transport and behavior of persistent organic pollutants (POPs). In the present work, surface soil samples were collected from the Tibetan Plateau, the highest plateau in the world which includes the northern slope of Mt. Qomolangma, to investigate the levels and trends of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) along the altitudinal gradient. The average PCB and PBDE concentrations were 185.6 ng kg-1 dry weight (dw) (range 47.1-422.6 ng kg-1 dw) and 11.1 ng kg-1 dw (range 4.3-34.9 ng kg-1 dw), respectively. Regression analysis between the log-transformed TOC-normalized concentrations and the altitudes of the sampling sites showed two opposite trends with regard to altitude dependence: negative relationship with altitude below about 4500 m followed by a positive altitude dependence above this point. Considering minimum anthropogenic activities and very sparse precipitation in the north of Himalayas, the trends above 4500 m imply that the significant altitude dependence of these two groups of POPs were irrespective of pollution sources, but could be predicted by the global distillation effect involving cold condensation in high altitude mountain areas. Increasing levels of heavier congeners were found in higher altitude sites, although the lighter congeners were the main contributors to the total amount, suggesting that less volatile congeners seem to become enriched easier than those more volatile at higher altitudes in this region.
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| 2. |
- Jiang, Jie, et al.
(författare)
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Integrated direct DNA/protein patterning and microfabrication by focused ion beam milling
- 2008
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Ingår i: Advanced Materials. - : John Wiley & Sons. - 0935-9648 .- 1521-4095. ; 20:9, s. 1636-1643
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Tidskriftsartikel (refereegranskat)abstract
- Single and binary component patterning and integrated microfabrication of biomolecules, such as DNA and proteins, can be achieved by focused ion-beam (FIB) biolithography. Well-defined micropatterns are obtained by FIB milling on biomolecules immobilized on SiO2 wafers and protected by a thin Au film. The retention of biofunctionality is excellent (68–90%) and a feature size of down to 500 nm can be achieved for the patterns without significant loss of functionality.
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| 3. |
- Meng, Zhou, et al.
(författare)
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Observation of the lower hybrid waves near the three-dimensional null pair
- 2009
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Ingår i: Science in China Series G. - : Science Press. - 1672-1799 .- 1862-2844. ; 52:4, s. 626-630
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic reconnection is a fundamental process in plasma, which is thought to play important roles both in laboratory and natural plasmas through affecting magnetic topology, heating and accelerating particles. During an event on Oct. 1st, 2001, the Cluster tetrahedron circled around the magnetic reconnection region several times, and Xiao et al. first identified the null pair and found that the spectrum of the null-point oscillation shows the maximum power near the lower-hybrid frequency. In this paper we report the observation of electromagnetic and electrostatic wave enhancements near lower hybrid frequency associated with the reconnection process near the null pair. The lower hybrid waves (LHWs) with quasi-perpendicular propagation were identified and also confirmed by the power law of the spectrum of electric and magnetic fields.
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