The variation of crustal thickness is a critical index to reveal how the continental crust evolved over its four billion years.Generally,ratios of whole-rock trace elements,such as Sr/Y,(La/Yb)n and Ce/Y,are used to c...The variation of crustal thickness is a critical index to reveal how the continental crust evolved over its four billion years.Generally,ratios of whole-rock trace elements,such as Sr/Y,(La/Yb)n and Ce/Y,are used to characterize crustal thicknesses.However,sometimes confusing results are obtained since there is no enough filtered data.Here,a state-of-the-art approach,based on a machine-learning algorithm,is proposed to predict crustal thickness using global major-and trace-element geochemical data of intermediate arc rocks and intraplate basalts,and their corresponding crustal thicknesses.After the validation processes,the root-mean-square error(RMSE)and the coefficient of determination(R2)score were used to evaluate the performance of the machine learning algorithm based on the learning dataset which has never been used during the training phase.The results demonstrate that the machine learning algorithm is more reliable in predicting crustal thickness than the conventional methods.The trained model predicts that the crustal thickness of the eastern North China Craton(ENCC)was-45 km from the Late Triassic to the Early Cretaceous,but-35 km from the Early Cretaceous,which corresponds to the paleo-elevation of 3.0±1.5 km at Early Mesozoic,and decease to the present-day elevation in the ENCC.The estimates are generally consistent with the previous studies on xenoliths from the lower crust and on the paleoenvironment of the coastal mountain of the ENCC,which indicates that the lower crust of the ENCC was delaminated abruptly at the Early Cretaceous.展开更多
Continuous ITQ-16 and ITQ-17 films on silicon wafer were prepared in fluoride media using TEAOH asorganic structure-directing agent. The proportion ofpolymorph C in the as-synthesized ITQ-16 and ITQ-17 films wasdeterm...Continuous ITQ-16 and ITQ-17 films on silicon wafer were prepared in fluoride media using TEAOH asorganic structure-directing agent. The proportion ofpolymorph C in the as-synthesized ITQ-16 and ITQ-17 films wasdetermined via X-ray diffraction characterization. The proportion of polymorph C in the ITQ-16 and 1TQ-17 filmswas controlled via optimizing the compositions of the reaction mixtures and reaction conditions, such as varyingthe Si/Ge molar ratio and adding n-propyl alcohol as a solvent in the reaction mixture, The Ge atoms in the reactionmedia strongly increased the crystallization of polymorph C in ITQ-16 and ITQ-17 films. Moreover, the stabilizingand buffering effect of n-propyl alcohol on crystal growth further enhanced the proportion of polymorph C in theITQ-16 and ITQ-17 films. For potential catalytic applications, A1 was incorporated into the framework ofpolymorphC, and a pure phase of polymorph C in Al-ITQ-17 film was achieved from the synthesis gel in the n-propyl alcohol phase.展开更多
Exploring the native defects of zeolites is highly important for understanding the properties of zeolites, such as catalysis and optics. Here, ITQ-16 films were prepared via the secondary growth method in the presence...Exploring the native defects of zeolites is highly important for understanding the properties of zeolites, such as catalysis and optics. Here, ITQ-16 films were prepared via the secondary growth method in the presence of Ge atoms. Various intrinsic defects of ITQ-16 films were fully studied through photoluminescence and FTIR characterizations. It was found that both the as-synthesized and calcined ITQ-16 films displayed multicolor photolumines- cence including ultraviolet, blue, green and red emissions by exciting upon appropriate wavelengths. The results in- dicate that Si--OH and non-bridging oxygen hole centers（NBOHCs） are responsible for the origin of green and red emissions at 540--800 nm, while according to a variety of emission bands of calcined ITQ-16 film, blue emission bands at around 446 and 462 nm are attributed to peroxy free radicals（≡SiO2＊）, ultraviolet emissions ranging from 250 nm to 450 nm are suggested originating from a singlet-to-triplet transition of two-fold-coordinated Si and Ge, respectively.展开更多
基金co-funded by the National Natural Science Foundation of China(Grant Nos.42002089,41930428)the National Key R&D Program of China(Grant Nos.2016YFC0600401 and 2017YFC0602302)+1 种基金by Open Research Fund Program of Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University)Ministry of Education(Grant Nos.2020YSJS02,2020YSJS01).
文摘The variation of crustal thickness is a critical index to reveal how the continental crust evolved over its four billion years.Generally,ratios of whole-rock trace elements,such as Sr/Y,(La/Yb)n and Ce/Y,are used to characterize crustal thicknesses.However,sometimes confusing results are obtained since there is no enough filtered data.Here,a state-of-the-art approach,based on a machine-learning algorithm,is proposed to predict crustal thickness using global major-and trace-element geochemical data of intermediate arc rocks and intraplate basalts,and their corresponding crustal thicknesses.After the validation processes,the root-mean-square error(RMSE)and the coefficient of determination(R2)score were used to evaluate the performance of the machine learning algorithm based on the learning dataset which has never been used during the training phase.The results demonstrate that the machine learning algorithm is more reliable in predicting crustal thickness than the conventional methods.The trained model predicts that the crustal thickness of the eastern North China Craton(ENCC)was-45 km from the Late Triassic to the Early Cretaceous,but-35 km from the Early Cretaceous,which corresponds to the paleo-elevation of 3.0±1.5 km at Early Mesozoic,and decease to the present-day elevation in the ENCC.The estimates are generally consistent with the previous studies on xenoliths from the lower crust and on the paleoenvironment of the coastal mountain of the ENCC,which indicates that the lower crust of the ENCC was delaminated abruptly at the Early Cretaceous.
文摘Continuous ITQ-16 and ITQ-17 films on silicon wafer were prepared in fluoride media using TEAOH asorganic structure-directing agent. The proportion ofpolymorph C in the as-synthesized ITQ-16 and ITQ-17 films wasdetermined via X-ray diffraction characterization. The proportion of polymorph C in the ITQ-16 and 1TQ-17 filmswas controlled via optimizing the compositions of the reaction mixtures and reaction conditions, such as varyingthe Si/Ge molar ratio and adding n-propyl alcohol as a solvent in the reaction mixture, The Ge atoms in the reactionmedia strongly increased the crystallization of polymorph C in ITQ-16 and ITQ-17 films. Moreover, the stabilizingand buffering effect of n-propyl alcohol on crystal growth further enhanced the proportion of polymorph C in theITQ-16 and ITQ-17 films. For potential catalytic applications, A1 was incorporated into the framework ofpolymorphC, and a pure phase of polymorph C in Al-ITQ-17 film was achieved from the synthesis gel in the n-propyl alcohol phase.
基金Supported by the Postdoctoral Science Foundation of China（No.2013M541716）, the Postdoctoral Science Foundation of Jiangsu Province, China（No.1301055C） and the Scientific Research Foundation for the Returned Overseas Chinese Scholars Sponsored by the Ministry of Education of China（No.K510900314）.
文摘Exploring the native defects of zeolites is highly important for understanding the properties of zeolites, such as catalysis and optics. Here, ITQ-16 films were prepared via the secondary growth method in the presence of Ge atoms. Various intrinsic defects of ITQ-16 films were fully studied through photoluminescence and FTIR characterizations. It was found that both the as-synthesized and calcined ITQ-16 films displayed multicolor photolumines- cence including ultraviolet, blue, green and red emissions by exciting upon appropriate wavelengths. The results in- dicate that Si--OH and non-bridging oxygen hole centers（NBOHCs） are responsible for the origin of green and red emissions at 540--800 nm, while according to a variety of emission bands of calcined ITQ-16 film, blue emission bands at around 446 and 462 nm are attributed to peroxy free radicals（≡SiO2＊）, ultraviolet emissions ranging from 250 nm to 450 nm are suggested originating from a singlet-to-triplet transition of two-fold-coordinated Si and Ge, respectively.
