The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and...The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and then tends to saturate with the increase of hydrogen–plasma flux.When the temperature of the sample eroded by hydrogen plasma is above 300°C,the hybridization of electrons outside the carbon atom would change.Then the carbon atoms combine with hydrogen atoms to form massive spherical nanoparticles of hydrocarbon compounds and deposit on the surface at the flux condition of 1.77×10^(22) m^(−2)·s^(−1).Under the irradiation of hydrogen plasma loaded with negative bias,the surface morphology of the matrix carbon is changed dramatically.Moreover,the energy dependence of mass loss does not increase in proportion to the increase of hydrogen–plasma energy,but reaches a peak around 20 V negative bias voltage.Based on the analysis of different samples,it can be concluded that the enhancement of energy could make a contribution to chemical erosion and enlarge the size of pores existing on the surface.展开更多
Cretaceous radiolarians were firstly reported from the Eocene Sand-Shale Member of Zhepure Formation in the Gulupu section, Tüna, Yadong, Tibet. In spite of poor preservation, 24 species of 14 radiolarian genera ...Cretaceous radiolarians were firstly reported from the Eocene Sand-Shale Member of Zhepure Formation in the Gulupu section, Tüna, Yadong, Tibet. In spite of poor preservation, 24 species of 14 radiolarian genera have still been identified, clearly indicating an age, ranging from early Aptian–Maastrichtian, and therefore should have occurred in the Eocene as a result of redeposition. The study of the stratigraphic origin of these radiolarians will shed light on the paleoenvironment and late evolutionary history of the Tibet-Tethys.展开更多
Inorganic and organic geochemical analyses,assisted by micropaleontological investigations,were performed on the Paskovac sediments to differentiate the Cretaceous and Paleogene deposits in Internal Dinarides region.O...Inorganic and organic geochemical analyses,assisted by micropaleontological investigations,were performed on the Paskovac sediments to differentiate the Cretaceous and Paleogene deposits in Internal Dinarides region.Owning to the presence of fossil assemblages in the in Upper Cretaceous sediments and their scarcity in the Paleogene siliciclastic sediments,the entire Paskovac area was fundamentally incorrectly classified as the Campanian–Maastrichtian.Besides,the Paskovac sedimentary sequence was formed as a consequence of the uppermost Cretaceous–Paleogene tectonic shortening of the Dinarides,during which the Maastrichtian sediments were re-deposited within the Paleogene sequence from the underlying Maastrichtian sediments.Therefore,this study employed thin-section microscopy,atomic absorption spectrometry(AAS),and gas chromatography–mass spectrometry(GC–MS)techniques to closely inspect 27 samples from the Paskovac drillhole.The results revealed a clear division of the samples into two groups based on their geochemical similarities.One group marked as Paleogene clastic sediments characterizes the highest content of terrigenous elements,namely SiO_(2)(49.49%–62.22%),Al_(2)O_(3)(16.18%–21.75%),Fe_(2)O_(3)(3.41%–6.67%),TiO_(2)(0.63%–0.80%),along with sulfur content(2.33%–2.80%).The organic matter is rich in odd long-chain n-alkanes,C_(29)regular sterane(>60%),benzohopanes,retene,cadalene,and benzo[b]naphthofurans,suggesting predominately terrestrial biomass deposited under suboxic–oxic conditions.Another group,represented by carbonates(CaO up to 51.02%),contains Maastrichtian assemblages(e.g.,Siderolites calcitrapoides),indicating shallow-marine depositional settings.Short-chain even n-alkanes,branched alkanes(e.g.,5,5-diethylalkanes),and C_(27)regular sterane suggest the presence of biodegraded mixed algal/microbial biomass.展开更多
基金by National Natural Science Foundation of China(No.11875198)Young Scientists Fund of National Natural Science Foundation of China(No.11905151)+1 种基金Fundamental Research Funds for the Central Universities of China(No.2019SCU12072)the China Postdoctoral Science Foundation(No.2019M663487).
文摘The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and then tends to saturate with the increase of hydrogen–plasma flux.When the temperature of the sample eroded by hydrogen plasma is above 300°C,the hybridization of electrons outside the carbon atom would change.Then the carbon atoms combine with hydrogen atoms to form massive spherical nanoparticles of hydrocarbon compounds and deposit on the surface at the flux condition of 1.77×10^(22) m^(−2)·s^(−1).Under the irradiation of hydrogen plasma loaded with negative bias,the surface morphology of the matrix carbon is changed dramatically.Moreover,the energy dependence of mass loss does not increase in proportion to the increase of hydrogen–plasma energy,but reaches a peak around 20 V negative bias voltage.Based on the analysis of different samples,it can be concluded that the enhancement of energy could make a contribution to chemical erosion and enlarge the size of pores existing on the surface.
文摘Cretaceous radiolarians were firstly reported from the Eocene Sand-Shale Member of Zhepure Formation in the Gulupu section, Tüna, Yadong, Tibet. In spite of poor preservation, 24 species of 14 radiolarian genera have still been identified, clearly indicating an age, ranging from early Aptian–Maastrichtian, and therefore should have occurred in the Eocene as a result of redeposition. The study of the stratigraphic origin of these radiolarians will shed light on the paleoenvironment and late evolutionary history of the Tibet-Tethys.
基金partly financed by the Ministry of Science,Technological Development and Innovation of the Republic of Serbia (Contract Numbers 451-03-136/2025-03/200026 and 451-03-136/2025-03/200168)
文摘Inorganic and organic geochemical analyses,assisted by micropaleontological investigations,were performed on the Paskovac sediments to differentiate the Cretaceous and Paleogene deposits in Internal Dinarides region.Owning to the presence of fossil assemblages in the in Upper Cretaceous sediments and their scarcity in the Paleogene siliciclastic sediments,the entire Paskovac area was fundamentally incorrectly classified as the Campanian–Maastrichtian.Besides,the Paskovac sedimentary sequence was formed as a consequence of the uppermost Cretaceous–Paleogene tectonic shortening of the Dinarides,during which the Maastrichtian sediments were re-deposited within the Paleogene sequence from the underlying Maastrichtian sediments.Therefore,this study employed thin-section microscopy,atomic absorption spectrometry(AAS),and gas chromatography–mass spectrometry(GC–MS)techniques to closely inspect 27 samples from the Paskovac drillhole.The results revealed a clear division of the samples into two groups based on their geochemical similarities.One group marked as Paleogene clastic sediments characterizes the highest content of terrigenous elements,namely SiO_(2)(49.49%–62.22%),Al_(2)O_(3)(16.18%–21.75%),Fe_(2)O_(3)(3.41%–6.67%),TiO_(2)(0.63%–0.80%),along with sulfur content(2.33%–2.80%).The organic matter is rich in odd long-chain n-alkanes,C_(29)regular sterane(>60%),benzohopanes,retene,cadalene,and benzo[b]naphthofurans,suggesting predominately terrestrial biomass deposited under suboxic–oxic conditions.Another group,represented by carbonates(CaO up to 51.02%),contains Maastrichtian assemblages(e.g.,Siderolites calcitrapoides),indicating shallow-marine depositional settings.Short-chain even n-alkanes,branched alkanes(e.g.,5,5-diethylalkanes),and C_(27)regular sterane suggest the presence of biodegraded mixed algal/microbial biomass.
