Studies of the chemical characteristics of mussels and clams in seafloor hydrothermal fields are important for understanding mass fluxes and elemental partitioning from hydrothermal vents into the biosphere, metal bio...
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Studies of the chemical characteristics of mussels and clams in seafloor hydrothermal fields are important for understanding mass fluxes and elemental partitioning from hydrothermal vents into the biosphere, metal bioaccumulation of seafloor hydrothermal ecosystems, and the sources and sinks of biogeochemical and fluid cycles. We are the first to measure the mineral, major, trace and rare earth element, and carbon and oxygen isotope compositions of mussels (Bathymodiolus platifrons) and clams (Conchocele bisecta) from the Tangyin and Yonaguni Knoll IV hydrothermal fields in the southwestern Okinawa Trough. Mineralogical analysis shows that the carbonate shells of the mussel and clam samples are mainly composed of calcite and aragonite. Metal elements exhibit linear correlations in the shells (e.g., V and U) and tissues (e.g., Li and Rb) of the mussels and clams, suggesting that not all positive correlations of elements in tissues are inherited by the shells. V/As, Ca/Sr, and Fe/Cr ratios in the mussels and clams are close to those in the seawater, indicating that element ratios of seawater might be inherited by the mussels and clams. In addition, the Fe/Cr ratio of the shells of both mussels and clams can be used to trace the local seawater composition. The total LREE concentrations of mussel and clam tissue samples are higher than those of the mussel and clam shell samples, are similar to the hydrothermal fluids, exhibit LREE enrichment (La-CN/Nd-CN ratios = 1.86-32.1), and no or only slightly negative Eu anomalies, indicating that benthic animals are a sink of LREEs from hydrothermal fluids, and that the Eu/Eu* ratios of fluids change when fluids are incorporated into the tissues of the mussels and clams. In addition, the delta C-13 values of mussel shell samples are heavier than those of the clam shell samples in the hydrothermal field, indicating that more than one carbon source may be involved in defining the delta C-13 compositions of the shells. The majority
A series of both unsupported and coal‐supported iron–oxygen compounds with gradual changes in microstructure were synthesized by a precipitation‐oxidation process at 20 to 70°*** relationship between the micro...
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A series of both unsupported and coal‐supported iron–oxygen compounds with gradual changes in microstructure were synthesized by a precipitation‐oxidation process at 20 to 70°*** relationship between the microstructures and catalytic activities of these precursors during direct coal liquefaction was *** results show that the microstructure could be controlled through adjusting the synthesis temperature during the precipitation‐oxidation procedure,and that compounds synthesized at lower temperatures exhibit higher catalytic *** a result of their higher proportions ofγ‐FeOOH orα‐FeOOH crystalline phases,the unsupported iron–oxygen compounds synthesized at 20–30°C,which also had high specific surface areas and moisture levels,generate oil yields 4.5%–4.6%higher than those obtained with precursors synthesized at 70°*** was also determined that higher oil yields were obtained when the catalytically‐active phase formed by the precursors during liquefaction(pyrrhotite,Fe1-xS)had smaller *** coal added as a carrier was found to efficiently disperse the active precursors,which in turn significantly improved the catalytic activity during coal liquefaction.
Manginoids A-G (1-7), seven monoterpene-shikimate-conjugated meroterpenoids with a spiro ring system, were isolated from Guignardia mangiferae. Compounds 1-4 are four isomers with epimeric and double-bond isomeric fea...
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Manginoids A-G (1-7), seven monoterpene-shikimate-conjugated meroterpenoids with a spiro ring system, were isolated from Guignardia mangiferae. Compounds 1-4 are four isomers with epimeric and double-bond isomeric features possessing a 6-oxaspiro[bicyclo[3.2.1]octane-3,5 '-indene] ring, which represent the first examples of spiro meroterpenoids bearing a bridged spirocyclohexanedione moiety. Compounds 5 and 6 possess an unexpected 2,4-dioxatricyclo[3.3.1.0(3,7)]nonane motif, which fuses with a 6-oxabicyclo[3.2.1]octane moiety. Compound 1 exhibits inhibitory activities against 11 beta-hydroxysteroid dehydrogenase type 1 with an IC50 value of 0.84 mu M.
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