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The transformation of chemically bound gold into metallic gold during industrial scale roasting of an arsenical gold ore concentrate from the Fairview Mine, Eastern Transvaal, has been studied quantitatively by197Au Mössbauer spectroscopy. The iron compounds in the concentrate, mainly FeAsS and FeS2 and their transformations during roasting have been studied by57Fe Mössbauer spectroscopy. The bound gold is found to convert into the metal in parallel to the decomposition of FeAsS and the increase in cyanide leachability. this shows that the refractory character of the ore is caused by the chemical bonding of the gold rather than by the physical inclusion of small, discrete metallic particles in the matrix of FeAsS or FeS2. The ratio of thef-factors of gold bound in the FeAsS component of a refractory ore and of metallic gold was determined to bef(Au:FeAsS)/f(Au)=1.48±0.09. 相似文献
84.
Cyclometalated Iridium(III) and Rhodium(III) Complexes Containing Naphthyridine Ligands: Synthesis,Characterization and Biological Studies 下载免费PDF全文
The synthesis, crystal structure, and biological activity of new bis‐cyclometalated compounds [M(ptpy)2(4‐chloro‐2‐methyl‐1,8‐naphthyridine)]PF6 [M = Rh ( 1 ); M = Ir ( 2 ); ptpy = 2‐(p‐tolyl)pyridinato] and [M(ptpy)2(2‐methyl‐1,8‐naphthyridine)]PF6 [M = Rh ( 3 ); M = Ir ( 4 )] are described. The new compounds were prepared by the reaction of [{M(μ‐Cl)(ptpy)2}2] (M = Rh, Ir) with the corresponding naphthyridine ligands. The molecular structures of compounds 1 , 3 , and 4 were confirmed by single‐crystal X‐ray diffraction studies. 相似文献
85.
Bernard Riss Marion Garreau Prisca Fricero Patricia Podsiadly Nicolas Berton Sophie Buchter 《Tetrahedron》2017,73(23):3202-3212
The absolute configuration of bisabolangelone has been established by an eleven step total synthesis of the corresponding TMS protected antipode starting from (R)-(+)-pulegone. Comparison of the TMS-derivatives by GC on a chiral column, allowed us to assign the absolute configuration of the synthetic compound and thus of the corresponding natural product. The latter has been confirmed by the Mosher's ester analysis of the known secondary carbinol derivative. 相似文献
86.
Marion Collinet-Fressancourt Nathalie Azaroual Jean-Marie Aubry Véronique Nardello-Rataj 《Tetrahedron letters》2010,51(50):6531-6534
The kinetic booster effect of dimethylsulfoxide on the chemical generation of singlet oxygen, 1O2, from the disproportionation of hydrogen peroxide catalyzed by molybdate ions in methanol has been evidenced by detection of the IR luminescence of 1O2 at 1270 nm and by 95Mo NMR spectroscopy. DMSO interacts rapidly, through a direct oxygen transfer with the stable tetraperoxomolybdate , leading to DMSO2 and to the unstable triperoxomolybdate , which releases 1O2. The procedure was applied to accelerate the dark singlet oxygenation of β-citronellol and α-terpinene. 相似文献
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Frédérick Adam Didier Thiébaut Fabrice Bertoncini Marion Courtiade Marie-Claire Hennion 《Journal of chromatography. A》2010,1217(8):1386-1394
This paper reports the conditions of online hyphenation of supercritical fluid chromatography (SFC) with twin comprehensive two-dimensional gas chromatography (twin-GC × GC) for detailed characterization of middle distillates; this is essential for a better understanding of reactions involved in refining processes. In this configuration, saturated and unsaturated compounds that have been fractionated by SFC are transferred on two different GC × GC columns sets (twin-GC × GC) placed in the same GC oven. Cryogenic focusing is used for transfer of fractions into the first dimension columns before simultaneous GC × GC analysis of both saturated and unsaturated fractions. The benefits of SFC–twin-GC × GC are demonstrated for the extended alkane, iso-alkane, alkene, naphthenes and aromatics analysis (so-called PIONA analysis) of diesel samples which can be achieved in one single injection. For that purpose, saturated and unsaturated compounds have been separated by SFC using a silver loaded silica column prior to GC × GC analysis. Alkenes and naphthenes are quantitatively recovered in the unsaturated and saturated fractions, respectively, allowing their identification in various diesel samples. Thus, resolution between each class of compounds is significantly improved compared to a single GC × GC run, and for the first time, an extended PIONA analysis of diesel samples is presented. 相似文献
89.
Andrea Retzbach Joachim Marschall Marion Rahnke Lukas Otto Michaela Maier 《Journal of nanoparticle research》2011,13(12):6231-6244
In this article, we report data from an online questionnaire study with 587 respondents, representative for the adult U.S.
population in terms of age, gender, and level of education. The aim of this study was to assess how interest in science and
knowledge as well as beliefs about science are associated with risk and benefit perceptions of nanotechnology. The findings
suggest that the U.S. public is still rather unfamiliar with nanotechnology. Those who have some knowledge mainly have gotten
it from TV and the Internet. The content of current media reports is perceived as fairly positive. Knowledge of scientific
methods is unrelated to benefit and risk perceptions, at least when other predictors are controlled. In contrast, positive
beliefs about science (e.g., its impact on economy or health) and more sophisticated epistemological beliefs about the nature
of scientific knowledge are moderately linked to more positive perceptions of nanotechnology. The only exception is the perception
of scientific uncertainty: This is associated with less positive evaluations. Finally, higher engagement with science is associated
with higher risk perceptions. These findings show that laypersons who are engaged with science and who are aware of the inherent
uncertainty of scientific evidence might perceive nanotechnology in a somewhat more differentiated way, contrary to how it
is portrayed in the media today. 相似文献
90.