Author
David J. Vaughan
Other affiliations: Lawrence Berkeley National Laboratory, Geoscience Research Institute, University of Oxford ...read more
Bio: David J. Vaughan is an academic researcher from University of Manchester. The author has contributed to research in topics: Sphalerite & Mackinawite. The author has an hindex of 61, co-authored 206 publications receiving 11937 citations. Previous affiliations of David J. Vaughan include Lawrence Berkeley National Laboratory & Geoscience Research Institute.
Topics: Sphalerite, Mackinawite, Adsorption, Pyrite, Absorption spectroscopy
Papers published on a yearly basis
Papers
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TL;DR: In this article, the authors introduce the concept of a geochemical switch, in which HS- transforms the marine behavior of a conservative element to that of a particle reactive element, and the action point of the HS- switch is calculated to be, a(HS)- = 10(-3.6) - 10(-4.3).
787 citations
TL;DR: In this paper, the most important steps in the overall process of the pyrite oxidation were mapped to the cathodic sites, where oxygen atoms from water molecules attach to the sulfur atoms to form sulfoxy species, through the crystal to cathodic Fe(II) sites where they are acquired by the oxidant species.
586 citations
TL;DR: In agreement with other workers, it is found that inner sphere complexes form, apparently involving bidentate (bridging) arsenate or arsenite, and this understanding of As mobility in near-surface environments is clarified.
Abstract: The mechanisms whereby As(III) and As(V) in aqueous solution (pH 5.5−6.5) interact with the surfaces of goethite, lepidocrocite, mackinawite, and pyrite have been investigated using As K-edge EXAFS and XANES spectroscopy. Arsenic species retain original oxidation states and occupy similar environments on the oxyhydroxide substrates, with first-shell coordination to four oxygens at 1.78 A for As(III) and 1.69 A for As(V). In agreement with other workers, we find that inner sphere complexes form, apparently involving bidentate (bridging) arsenate or arsenite. Interaction of As(III) and As(V) with the sulfide surfaces shows primary coordination to four oxygens (As−O: 1.69−1.76 A) with further sulfur (∼3.1 A) and iron (3.4−3.5 A) shells suggesting outer sphere complexation. Arsenic species were also coprecipitated with mackinawite (pH 4.0), and these samples were further studied following oxidation. At high As(III) or As(V) concentrations, arsenate or arsenite species form, probably as sorption complexes, al...
464 citations
TL;DR: In this article, the results of a review that has been conducted to establish the range in variability of natural pyrite with regard to chemical composition, texture and electrical properties are presented.
399 citations
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28 Jul 2005
TL;DR: PfPMP1）与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。
18,940 citations
TL;DR: In this article, the absolute energy positions of conduction and valence band edges were compiled for about 50 each semiconducting metal oxide and metal sulfide minerals, and the relationship between energy levels at mineral semiconductor-electrolyte interfaces and the activities of these minerals as a catalyst or photocatalyst in aqueous redox reactions were reviewed.
Abstract: The absolute energy positions of conduction and valence band edges were compiled for about 50 each semiconducting metal oxide and metal sulfide minerals. The relationships between energy levels at mineral semiconductor-electrolyte interfaces and the activities of these minerals as a catalyst or photocatalyst in aqueous redox reactions are reviewed. The compilation of band edge energies is based on experimental flatband potential data and complementary empirical calculations from electronegativities of constituent elements. Whereas most metal oxide semiconductors have valence band edges 1 to 3 eV below the H2O oxidation potential (relative to absolute vacuum scale), energies for conduction band edges are close to, or lower than, the H2O reduction potential. These oxide minerals are strong photo-oxidation catalysts in aqueous solutions, but are limited in their reducing power. Non-transition metal sulfides generally have higher conduction and valence band edge energies than metal oxides; therefore, valence band holes in non-transition metal sulfides are less oxidizing, but conduction band electrons are exceedingly reducing. Most transition-metal sulfides, however, are characterized by small band gaps (<1 eV) and band edges situated within or close to the H2O stability potentials. Hence, both the oxidizing power of the valence band holes and the reducing power of the conduction band electrons are lower than those of non-transition metal sulfides.
3,145 citations
01 Jan 1990
TL;DR: An overview of the self-organizing map algorithm, on which the papers in this issue are based, is presented in this article, where the authors present an overview of their work.
Abstract: An overview of the self-organizing map algorithm, on which the papers in this issue are based, is presented in this article.
2,933 citations
TL;DR: In this paper, a synthesis of the use of selected trace elements as proxies for reconstruction of paleoproductivity and paleoredox conditions is presented, and the combined used of U, V and Mo enrichments may allow suboxic environments to be distinguished from anoxic-euxinic ones.
2,708 citations
TL;DR: A review of the fundamental interactions of water with solid surfaces can be found in this paper, where the authors assimilated the results of the TM review with those covered by the authors to provide a current picture of water interactions on solid surfaces, such as how water adsorbs, what are the chemical and electrostatic forces that constitute the adsorbed layer, how is water thermally or non-thermally activated and how do coadsorbates influence these properties of water.
2,022 citations