The Okinawa Trough is characterized by enrichment of Ag in hydrothermal precipitates;however, the distribution of this enrichment remains poorly constrained. This study presents the results of a field-emission scannin...The Okinawa Trough is characterized by enrichment of Ag in hydrothermal precipitates;however, the distribution of this enrichment remains poorly constrained. This study presents the results of a field-emission scanning electron microscopy and electron-microprobe analysis based mineralogical and geochemical investigation of the spatial distribution of Ag within Ag-rich sulfide samples from the Okinawa Trough. The tetrahedrite, covellite, and galena in these samples contain high concentrations of Ag(average values of 1.60, 0.78, and 0.23 wt%, respectively) and also various Ag sulfosalts. Examination of the Ag budget of these samples indicates that most of the Ag is hosted by tetrahedrite followed by galena. The Ag within tetrahedrite is incorporated by substitution into the Cu site, whereas galena becomes Ag-enriched by the coupled incorporation of monovalent Ag, Tl, and Cu, and trivalent Sb and Bi into Pb lattice sites. Tetrahedrite and galena containing higher concentrations of Sb favor increased Ag substitution. Four sets of Ag host minerals are identified with distinct ore formation temperatures. Tetrahedrite and galena concentrate the majority of Ag at medium temperatures(150–300°C). Other Ag host minerals concentrate only minor or trace amounts of Ag, including massive sphalerite, chalcopyrite, and pyrite at high temperatures(>300°C), colloform pyrite and sphalerite at low temperatures(<150°C), and Ag-sulfosalts at even lower temperatures(<100°C).展开更多
在20世纪现代家具风起云涌、丰富多彩的舞台上,二战后的美国现代家具设计是其中重要的设计学派。尤其是在20世纪50年代迅速崛起,引领了世界家具设计潮流,出现了以查尔斯和蕾·伊姆斯(Charles and Ray Eames)夫妇、埃罗·沙里宁(...在20世纪现代家具风起云涌、丰富多彩的舞台上,二战后的美国现代家具设计是其中重要的设计学派。尤其是在20世纪50年代迅速崛起,引领了世界家具设计潮流,出现了以查尔斯和蕾·伊姆斯(Charles and Ray Eames)夫妇、埃罗·沙里宁(Eero Saarihen)、哈里·贝尔托亚(Harry Bertoia)和乔治·尼尔森(George Nelson)展开更多
Cytokinesis, the partitioning of the cytoplasm following nuclear division, requires extensive coordination between membrane trafficking and cytoskeletal dynamics. In plants, the onset of cytokinesis is characterized b...Cytokinesis, the partitioning of the cytoplasm following nuclear division, requires extensive coordination between membrane trafficking and cytoskeletal dynamics. In plants, the onset of cytokinesis is characterized by the assembly of a bipolar microtubule array, the phragmoplast, and of a transient membrane compartment, the cell plate. Little is known about the coordination between membrane deposition at the cell plate and the dynamics of phragmoplast microtubules. In this study, we monitor the localization dynamics of microtubule and membrane markers throughout cytokinesis. Our spatiotemporal resolution is consistent with the general view that microtubule dynamics drive membrane movements. Nonetheless, we provide evidence for active sorting at the cell plate and show that this is, at least in part, mediated by the TRAPPII tethering complex. We also characterize phragmoplast microtubule organization and cell plate formation in a suite of cytokinesis-defective mutants. Of four mutant lines with defects in phragmoplast microtubule organization, only morl microtubule-associated mutants exhibited aberrant cell plates. Conversely, the mutants with the strongest impairment in phragmoplast microtubule reorganization are keule alleles, which have a primary defect in membrane fusion. Our findings identify the SEC1/Munc18 protein KEULE as a central regulatory node in the coordination of membrane and microtubule dynamics during plant cytokinesis.展开更多
基金supported by the National Research Plan of China(Grant No.2016YFC0301803)Scientific Fund of the Second Institute of Oceanography,MNR of China(Grant No.JG1702,JG1605)the Zhejiang Provincial Natural Science Foundation(Grant No.LQ17D060005,LQ17D060004,LZ16D060001).
文摘The Okinawa Trough is characterized by enrichment of Ag in hydrothermal precipitates;however, the distribution of this enrichment remains poorly constrained. This study presents the results of a field-emission scanning electron microscopy and electron-microprobe analysis based mineralogical and geochemical investigation of the spatial distribution of Ag within Ag-rich sulfide samples from the Okinawa Trough. The tetrahedrite, covellite, and galena in these samples contain high concentrations of Ag(average values of 1.60, 0.78, and 0.23 wt%, respectively) and also various Ag sulfosalts. Examination of the Ag budget of these samples indicates that most of the Ag is hosted by tetrahedrite followed by galena. The Ag within tetrahedrite is incorporated by substitution into the Cu site, whereas galena becomes Ag-enriched by the coupled incorporation of monovalent Ag, Tl, and Cu, and trivalent Sb and Bi into Pb lattice sites. Tetrahedrite and galena containing higher concentrations of Sb favor increased Ag substitution. Four sets of Ag host minerals are identified with distinct ore formation temperatures. Tetrahedrite and galena concentrate the majority of Ag at medium temperatures(150–300°C). Other Ag host minerals concentrate only minor or trace amounts of Ag, including massive sphalerite, chalcopyrite, and pyrite at high temperatures(>300°C), colloform pyrite and sphalerite at low temperatures(<150°C), and Ag-sulfosalts at even lower temperatures(<100°C).
文摘在20世纪现代家具风起云涌、丰富多彩的舞台上,二战后的美国现代家具设计是其中重要的设计学派。尤其是在20世纪50年代迅速崛起,引领了世界家具设计潮流,出现了以查尔斯和蕾·伊姆斯(Charles and Ray Eames)夫妇、埃罗·沙里宁(Eero Saarihen)、哈里·贝尔托亚(Harry Bertoia)和乔治·尼尔森(George Nelson)
文摘Cytokinesis, the partitioning of the cytoplasm following nuclear division, requires extensive coordination between membrane trafficking and cytoskeletal dynamics. In plants, the onset of cytokinesis is characterized by the assembly of a bipolar microtubule array, the phragmoplast, and of a transient membrane compartment, the cell plate. Little is known about the coordination between membrane deposition at the cell plate and the dynamics of phragmoplast microtubules. In this study, we monitor the localization dynamics of microtubule and membrane markers throughout cytokinesis. Our spatiotemporal resolution is consistent with the general view that microtubule dynamics drive membrane movements. Nonetheless, we provide evidence for active sorting at the cell plate and show that this is, at least in part, mediated by the TRAPPII tethering complex. We also characterize phragmoplast microtubule organization and cell plate formation in a suite of cytokinesis-defective mutants. Of four mutant lines with defects in phragmoplast microtubule organization, only morl microtubule-associated mutants exhibited aberrant cell plates. Conversely, the mutants with the strongest impairment in phragmoplast microtubule reorganization are keule alleles, which have a primary defect in membrane fusion. Our findings identify the SEC1/Munc18 protein KEULE as a central regulatory node in the coordination of membrane and microtubule dynamics during plant cytokinesis.
