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  • 1
    Electronic Resource
    Electronic Resource
    Geochemistry of metals in sediments from the mainstem of the Yellow River, China (1996)
    Springer
    GeoJournal 40 (1996), S. 181-185 
    Details
    ISSN: 1572-9893
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract Sediment samples at 10 locations in the mainstem of the Yellow River were taken in 1994. Five forms (exchangeable, carbonate, organic, Fe/Mn oxide and residual) of metals were extracted by the Tessier method. The total contents and contents of the five forms of 16 metal elements (Li, Na, K, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Al) were determined by ICP-AES. In sediments of the Yellow River, except for Na, mobile elements (such as K, Ca) do not show a negative correlation with the immobile elements. Alkaline metals (Li, Na, and K), Ti, and Al exist mainly in the residual form. The exchangeable forms of alkaline-earth elements (Ca, Sr, and Ba) are the highest, and their residual forms go up with the increase of the period in the periodic table of elements. Half of Mn exists in the residual form, and its non-residual forms exist mainly in carbonate and oxide forms. Except Mn, the iron group elements (Fe, Co, Ni, V, Cr) mainly exist in the residual and oxide forms. High carbonate content of Ca does not cause high contents of other elements in carbonate form, showing that chemical weathering is not strong in the area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222543
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A robust-symmetric mean: A new way of mean calculation for environmental data (1996)
    Springer
    GeoJournal 40 (1996), S. 209-212 
    Details
    ISSN: 1572-9893
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract Environmental data seldom follow normal distributions, so how to calculate their means is a very important problem. Commonly used methods for mean calculation, such as arithmetic mean, geometric mean, and median, were evaluated. Arithmetic means should only be used when datasets follow normal distributions. Geometric means are suitable for datasets which follow log-normal distributions. Medians are a kind of robust treatment. However, their ‘efficiency’ is very low. Based on the methods described, two new ideas are developed: ‘robust’ and ‘symmetric’, for calculating means. As far as the symmetric feature is concerned, Box-Cox power transformation is better than logarithmic transformation. Robust statistics and Box-Cox transformation are combined to produce the ‘robust-symmetric mean’. As environmental data often follow log-normal or skewed distributions, this method is better than the previous ones and also is appropriate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222547
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    Paper (German National Licenses)
    Fulltext
  • 3
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    Simultaneous measurement of fifteen rare earth elements using diffusive gradients in thin films (2018)
    Elsevier
    In:  Analytica Chimica Acta, 1031 . pp. 98-107.
    Details
    Publication Date: 2021-09-29
    Description: Highlights • DGT is a feasible technique for simultaneous measurement of REEs in soils. • REE elution efficiencies ranged from 86.5% to 93.8% using 2 M HCl. • DGT uptake was independent of solution pH (3–9) and ionic strength (3 mM- 100 mM). • Chelex®100 DGT had capacities of 5.39–6.75 μg cm−2 for measurement of mixed REEs. A new method for simultaneous measurement of fifteen rare earth elements (REEs) [La (Ⅲ), Ce (Ⅲ), Pr (Ⅲ), Nd (Ⅲ), Sm (Ⅲ), Eu (Ⅲ), Gd (Ⅲ), Tb (Ⅲ), Dy (Ⅲ), Ho (Ⅲ), Er (Ⅲ), Tm (Ⅲ), Yb (Ⅲ), Lu (Ⅲ), and Y (Ⅲ)] was established in this study using the diffusive gradients in thin films (DGT) technique with Chelex®100 binding gel. Five different types of ion exchange resins (Chelex®100, D418, D001-cc, 001 × 7, and HSTY®-SS) were selected for the initial investigation of their adsorption performance for REEs. The Chelex®100 binding gel had the greatest uptake efficiencies of 〉95% for the fifteen REE ions, which was used for all subsequent experiments. The binding gel exhibited rapid binding dynamics to REEs in mixed solution of the fifteen REE ions. Elution efficiencies ranging from 86.5% to 93.8% for these REEs were obtained based on extraction using 2.0 M HCl. The Chelex®100 DGT uptake of the fifteen REE ions increased linearly with the deployment time and found to be independent of pH (3–9) and ionic strength (3 mM–100 mM). The capacities of Chelex®100 DGT for measurement of the mixed elements were determined at a range of 5.39–6.75 μg cm−2. Application of the DGT for soil analysis showed that Chelex®100 DGT was a useful tool in simultaneous measurement of the fifteen REE ions, even in a soil with high concentrations of REEs. This study demonstrated the advantage of Chelex®100 DGT in simultaneous measurement of the fifteen REE ions due to high uptake efficiencies and a wide tolerance to environmental interference.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.aca.2018.05.067
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Cooperative and Competitive Dynamics Model for Information Propagation in Online Social Networks (2014)
    Hindawi
    Details
    Publication Date: 2014-07-14
    Description: Traditional empirical models of propagation consider individual contagion as an independent process, thus spreading in isolation manner. In this paper, we study how different contagions interact with each other as they spread through the network in order to propose an alternative dynamics model for information propagation. The proposed model is a novel combination of Lotka-Volterra cooperative model and competitive model. It is assumed that the interaction of one message on another is flexible instead of always negative. We prove that the impact of competition depends on the critical speed of the messages. By analyzing the differential equations, one or two stable equilibrium points can be found under certain conditions. Simulation results not only show the correctness of our theoretical analyses but also provide a more attractive conclusion. Different types of messages could coexist in the condition of high critical speed and intense competitive environment, or vice versa. The messages will benefit from the high critical speed when they are both competitive, and adopting a Tit-for-Tat strategy is necessary during the process of information propagation.
    Print ISSN: 1110-757X
    Electronic ISSN: 1687-0042
    Topics: Mathematics
    Published by Hindawi
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    PAPER CURRENT
  • 5
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    Risk factors of progressive IgA nephropathy which progress to end stage renal disease within ten years: a case–control study (2017)
    BioMed Central
    Details
    Publication Date: 2017-01-09
    Description: There were few related studies aiming to severe IgA nephropathy (IgAN) which could progress rapidly to end stage renal disease (ESRD) within ten years. To find valuable clinical or pathological factors and pro...
    Electronic ISSN: 1471-2369
    Topics: Medicine
    Published by BioMed Central
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    PAPER CURRENT
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