852 results on '"Weidong Sun"'
Search Results
202. Extracting 3D Contour Features of Urban Scenes from Ground-Based Laser Range Data.
- Author
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Weidong Sun, Shaoxing Hu, Cheng Qian, and Aiwu Zhang
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- 2004
- Full Text
- View/download PDF
203. Automatic global registration of multiple 3D data sets from outdoor urban environments based on feature units.
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Aiwu Zhang, Weidong Sun, Shaoxing Hu, and Chen Qian
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- 2004
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- View/download PDF
204. Trace element characteristics of pyrite in Dongguashan Cu (Au) deposit, Tongling region, China
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Lin Qian, Weidong Sun, Likai Ge, Jiancheng Xie, and Quanzhong Li
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Mineralization (geology) ,010504 meteorology & atmospheric sciences ,Geochemistry ,Dongguashan Cu (Au) deposit ,Skarn ,Electron microprobe ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Geochemistry and Petrology ,Trace element composition ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Trace elements ,Laser ablation ICP-MS ,Pyrite ,Chemistry ,lcsh:QE1-996.5 ,Eastern china ,Trace element ,Geology ,Tongling region ,Geotechnical Engineering and Engineering Geology ,lcsh:Geology ,Geophysics ,engineering ,Sedimentary rock - Abstract
The Dongguashan deposit is the largest and deepest Cu (Au) deposit in the Tongling region, eastern China. The presence of skarn and stratiform ore bodies in the same system of the Dongguashan deposit has caused much debate as to whether the mineralization was associated with magmatic-hydrothermal or sedimentary origin. In this study, in situ (LA-ICP-MS and EPMA) elemental compositions of medium-to coarse-grained euhedral pyrite from the stratiform and skarn ore bodies, and pyritization marble are investigated in the Dongguashan deposit. The results of the studied pyrite samples have relatively consistent trace element composition characteristics and several genetically significant elemental combinations. Gold and Ag are mainly of lattice bound appearance in pyrite. The Pb, Cu, Sb and Tl elements are mainly incorporated into the pyrite structure as substitutions. The distinctly trace element distribution correlations (e.g., Mn, Se and Tl) of the studied pyrites indicate that they were formed in a high temperature and oxidizing environment. Low Au (1) and Se/Tl (>10) ratios of the studied pyrites imply that the Dongguashan deposit is most likely to be a magmatic-hydrothermal origin.
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- 2020
205. Super-Resolution Based on Compressive Sensing and Structural Self-Similarity for Remote Sensing Images.
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Zongxu Pan, Jing Yu 0005, Huijuan Huang, Shaoxing Hu, Aiwu Zhang, Hongbing Ma, and Weidong Sun
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- 2013
- Full Text
- View/download PDF
206. A Small and Lightweight Autonomous Laser Mapping System without GPS.
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Shaoxing Hu, Chunpeng Chen, Aiwu Zhang, Weidong Sun, and Linlin Zhu
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- 2013
- Full Text
- View/download PDF
207. Combined mica and apatite chemical compositions to trace magmatic-hydrothermal evolution of fertile granites in the Dachang Sn-polymetallic district, South China
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Jia Guo, Gangyang Zhang, Lu Xiang, Rongqing Zhang, Lipeng Zhang, and Weidong Sun
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Geochemistry and Petrology ,Economic Geology ,Geology - Published
- 2022
208. Facile access to high-performance reverse intersystem crossing OLED materials through an unsymmetrical D-A-D’ molecular scaffold
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Caixia Fu, Weidong Sun, Yihuan Zhao, Ming Sun, Chuan Li, Liang Zhou, Yan Huang, Xuemei Pu, Yu Liu, and Zhiyun Lu
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General Chemical Engineering ,Environmental Chemistry ,General Chemistry ,Industrial and Manufacturing Engineering - Published
- 2022
209. Ocean circulation and climate variability in the northern South China Sea during the Greek Minimum derived from coral Δ14C and Sr/Ca records
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Ning Wang, Chengde Shen, Ping Ding, Xingfang Ding, Kexin Liu, Weidong Sun, Xuefei Chen, Wenfeng Deng, and Gangjian Wei
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Paleontology ,Oceanography ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Published
- 2022
210. In situ Raman spectroscopic experiments support the sulfate reduction model of porphyry deposits
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Weidong Sun and Xiuqi Shang
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In situ ,Reduction (complexity) ,chemistry.chemical_compound ,symbols.namesake ,Multidisciplinary ,chemistry ,symbols ,Sulfate ,Raman spectroscopy ,Nuclear chemistry - Published
- 2021
211. A supercritical carbon dioxide layer in the Hadean atmosphere for the origin of life?
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Yu-Fen Zhao, Yi-Liang Li, and Weidong Sun
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Atmosphere ,Multidisciplinary ,Supercritical carbon dioxide ,Chemistry ,Abiogenesis ,Hadean ,Layer (electronics) ,Astrobiology - Published
- 2021
212. Occurrence of Halogenated Organic Pollutants in Hadal Trenches of the Western Pacific Ocean
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Zhiqiang Yu, Lisheng He, Mei Mi, Juntao Cui, Weidong Sun, Jiasong Fang, Peng Yao, and Zhongli Sha
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Pollutant ,Pacific Ocean ,Detritus ,Sediment ,Hadal zone ,General Chemistry ,010501 environmental sciences ,Pesticide ,Polychlorinated Biphenyls ,01 natural sciences ,Polybrominated diphenyl ethers ,Environmental chemistry ,Bioaccumulation ,Halogenated Diphenyl Ethers ,Hydrocarbons, Chlorinated ,Animals ,Environmental Chemistry ,Environmental science ,Environmental Pollutants ,Polybrominated Biphenyls ,Water Pollutants, Chemical ,Environmental Monitoring ,0105 earth and related environmental sciences - Abstract
The hadal trenches are the most remote and inaccessible habitats on earth and were once believed to be pristine. A recent study has reported the detection of high levels of persistent organic pollutants (POPs), including polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs), in endemic amphipods from two hadal trenches (Mariana and Kermadec) in the Western Pacific, implicating that the trenches are indeed polluted. However, a fundamental question remains unanswered, if and to what extent such the physical environment of the trenches is polluted by POPs. In this study, we sampled Mariana, Mussau, and New Britain trenches and analyzed samples of amphipods, sediment, and suspended particulate matter (SPM). Our results show that the amphipods contained elevated levels of PCBs and PBDEs, comparable to those reported in the earlier study. We also detected significantly high concentrations (up to 1343 ng g-1 lw) of chlorinated pesticides, such as dichlorodiphenyltrichloroethanes and chlordanes. Furthermore, four brominated natural products (BNPs), which structurally resembled methoxylated brominated diphenyl ethers or polybrominated biphenyls, were identified in the endemic amphipods. However, neither POPs nor BNPs were detected in sediments or SPM. Taken together, we propose that the POPs detected in endemic amphipods likely resulted from bioaccumulation by feeding on polluted large detritus (e.g., carrion) falling to the trench bottoms from the surface ocean.
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- 2020
213. Coupled Fe–S isotope composition of sulfide chimneys dominated by temperature heterogeneity in seafloor hydrothermal systems
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Shikui Zhai, Huaiming Li, Jing Huang, Weidong Sun, and Shujie Wang
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chemistry.chemical_classification ,Multidisciplinary ,Sulfide ,Isotope ,Mineralogy ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Hydrothermal circulation ,Seafloor spreading ,δ34S ,Isotope fractionation ,chemistry ,engineering ,Chimney ,Pyrite ,Geology ,0105 earth and related environmental sciences - Abstract
Seafloor hydrothermal chimneys are significant metal resources and have fundamental effects on marine chemistry balance. Previous studies on growth of the chimneys focused on mineral composition and elemental distribution in chimney walls, but the isotopic composition of different elements and their correlations remain poorly understood. Here, we report lateral Fe and S isotopes from sulfides across a chimney wall in detail from the Deyin-1 hydrothermal field (DHF) on the South Mid-Atlantic Ridge. Pyrite was characterized by increases in both δ34S and δ56Fe from the exterior to the interior within the chimney wall, which is likely related to enhanced S and Fe isotope fractionation between pyrite and fluids derived from the temperature gradient. Furthermore, δ56Fe displayed a well-defined, linear, positive correlation with δ34S in pyrite from the DHF as well as in pyrite from other areas. A model of hydrothermal pyrite formation suggests that, under conditions with uniform hydrothermal fluid, different temperatures and similar pyrite–fluid exchange degrees could result in the observed linear relationships between δ34S and δ56Fe. The regular and coupled Fe–S isotope variations within the chimney wall efficiently constrain the process of hydrothermal sulfide formation.
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- 2020
214. Late Cambrian tonalite-trondhjemite association in the eastern segment of North Qilian suture zone: petrogenesis and geodynamic implications
- Author
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Lipeng Zhang, Tangfu Xiao, Yuxiao Chen, Weidong Sun, Shanming Fu, Ying Cui, and Shuguang Song
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Tectonics ,Fractional crystallization (geology) ,020209 energy ,0202 electrical engineering, electronic engineering, information engineering ,Geochemistry ,Geology ,02 engineering and technology ,Suture (geology) ,010502 geochemistry & geophysics ,01 natural sciences ,0105 earth and related environmental sciences ,Petrogenesis - Abstract
The late Cambrian tonalite-trondhjemite association in the eastern segment of North Qilian suture zone (E. NQSZ) is important for understanding of the sub-arc magmatic process and tectonic evolutio...
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- 2020
215. Early cretaceous transformation from Pacific to Neo-Tethys subduction in the SW Pacific Ocean: Constraints from Pb-Sr-Nd-Hf isotopes of the Philippine arc
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Weidong Sun, He Liu, Huasheng Qi, Al Emil Berador, Jianghong Deng, Lipeng Zhang, Xiaoyong Yang, Abdul Shakoor Mastoi, Zhaofeng Zhang, and Robert E. Zartman
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Provenance ,010504 meteorology & atmospheric sciences ,Subduction ,Pacific Plate ,Partial melting ,010502 geochemistry & geophysics ,01 natural sciences ,Cretaceous ,Mantle (geology) ,Paleontology ,Geochemistry and Petrology ,Adakite ,Island arc ,Geology ,0105 earth and related environmental sciences - Abstract
The westward subduction of the Pacific plate interacted with the northward subduction of the eastern Neo-Tethys plate in the Early Cretaceous. However, the subduction polarities between these two plates in the Early Cretaceous is not well constrained. The proto-Philippine arc is suggested to have originated at the Pacific – Neo-Tethys intersection in the SW Pacific in the latest Jurassic – Early Cretaceous, and can provide information about the ancient interaction between these two plates. In this study, the oldest known Early Cretaceous mantle-derived arc volcanic rocks and slab-melting generated adakites occurring in the Philippine arc have been studied for Pb, Sr, Nd and Hf isotopes to discriminate the provenance of their mantle sources and/or subduction components. The 126–118 Ma Kansi island arc volcanics have Pacific-type Pb isotopes, suggesting that the subduction components in the source are mainly from the subducted Pacific plate. Their Hf-Nd isotopes give support to a mantle source that is isotopically transitional Pacific-Indian type. The formation of the Kansi volcanics dates the subduction of the Pacific plate under the transitional Pacific-Indian mantle as Early Cretaceous. The subsequent generation of the 110 Ma Kansi adakitic diorites with the similar Pacific-type Pb isotopes indicates further partial melting of the subducted Pacific plate. In contrast, the post-110 Ma Lutopan adakitic diorites have Indian-type Pb isotopes, indicating the subsequent subduction of an Indian-type oceanic slab in the eastern Neo-Tethys tectonic regime. Therefore, the proto-Philippine arc is constrained to have originated at the intersection between Indian-type and Pacific-type oceanic crusts and mantle domains. The successive generation of these Early Cretaceous arc rocks in the Philippines indicates that a transformation of the tectonic regime from southwestward Pacific subduction to northeastward subduction of the eastern Neo-Tethys plate in the SW Pacific Ocean occurred at ca. 110 Ma, due to the abrupt change in drifting direction of the Pacific plate.
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- 2020
216. Geochemistry and genesis of the Nadun Nb-enriched arc basalt in the Duolong mineral district, western Tibet: Indication of ridge subduction
- Author
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Cai Li, Ming Wang, Jianghong Deng, Tian-Yu Zhang, Weidong Sun, and Lipeng Zhang
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Basalt ,QE1-996.5 ,Mantle wedge ,Subduction ,Geochemistry ,Trace element ,Nb-enriched arc basalt ,Ridge subduction ,Geology ,Tethys ocean ,Tibet ,Rhyolite ,Adakite ,General Earth and Planetary Sciences ,Island arc ,Duolong porphyry Cu–Au deposit ,Zircon - Abstract
The Duolong mineral district in western Tibet is one of the largest porphyry Cu–Au deposit fields with significant metallogenic potential in China. Its tectonic environment relevant to Early Cretaceous Cu–Au mineralization remains controversial. Here we report new whole-rock major and trace element, and Sr-Nd-Hf-Pb isotopic data for the newly discovered basalt in the Nadun area, Duolong mineral district, to decipher their genesis and further constrain the tectonic environment. A contemporaneous rhyolite sample interbedded with the basalt in the lower part of the volcanic section in the Nadun area yields an LA-ICP-MS zircon U–Pb age of 122.5 ± 1.2 Ma. The basalt samples exhibit high-K calc-alkaline/shoshonite properties and are enriched in high field strength elements, e.g., high TiO2 (1.43–1.79 wt.%) and Nb (14.6–19.5 ppm) contents, with high Nb/La ratios (0.4–0.6), which are compositionally comparable to those of Nb-enriched arc basalts (NEABs). The (87Sr/86Sr)i ratios of 0.7052 to 0.7056, negative eNd(t) (− 0.7 to − 0.2) and eHf(t) values (+ 6.0 to + 6.5), and high (206Pb/204Pb)i, (207Pb/204Pb)i, (208Pb/204Pb)i and ratios (18.522 to 18.561, 15.641 to 15.645 and 38.679 to 38.730, respectively) suggest that the Nadun NEABs are more enriched than those of the island arc basalts (IABs) in the area. The slightly enriched radiogenic isotopes for the Nadun NEABs indicate that the subducting sediments play an important role in the source. Furthermore, their high Nb, Ti, and Cu contents indicate that the source mantle wedge was metasomatized by slab melts. The Nadun NEAB and other coeval magmatic rocks in the Duolong mineral district, including adakite, OIB-like basalt, MORB-type basalt, A-type rhyolite, and common IAB, are typical rock assemblages of ridge subduction. We infer that the Duolong mineral district were formed by ridge subduction in the Early Cretaceous.
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- 2022
217. Large iron isotope fractionation during mantle wedge serpentinization
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Weidong Sun, Jianghong Deng, Robert Zartman, Yongsheng He, and Xiaoyong Yang
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- 2022
218. Geochemical Systematics of Continental versus Island Arcs and Implications for Resource-endowed Continent Forming
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Chen Chen and Weidong Sun
- Published
- 2022
219. Oxidative Coupling of Methane: Examining the Inactivity of the MnO
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Jiaqi, Si, Guofeng, Zhao, Weidong, Sun, Jincun, Liu, Cairu, Guan, Yong, Yang, Xue-Rong, Shi, and Yong, Lu
- Abstract
Oxidative coupling of methane (OCM) catalyzed by MnO
- Published
- 2021
220. Self-oxygenation mesoporous MnO
- Author
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Weidong, Sun, Yiyan, Xu, Ye, Yao, Jie, Yue, Zhen, Wu, Haocheng, Li, Guanghui, Shen, Yan, Liao, Haiyang, Wang, and Wenhu, Zhou
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Mice ,Manganese Compounds ,Animals ,Nanoparticles ,Oxides ,Hydrogen Peroxide ,Atherosclerosis - Abstract
Atherosclerosis (AS) is a leading cause of vascular diseases that severely threats the human health due to the lack of efficient therapeutic methods. During the development and progress of AS, macrophages play critical roles, which are polarized into pro-inflammatory M1 phenotype to excrete abundant cytokines and overproduce reactive oxygen species (ROS), and take up excess amount of lipid to form foam cells. In this work, we developed a MnO
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- 2021
221. Late Ordovician mass extinction caused by global warming or cooling?
- Author
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Weidong Sun and Renqiang Liao
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Extinction event ,Extinction ,Geochemistry and Petrology ,Earth science ,Global warming ,Ordovician ,Environmental science ,Marine species ,Global cooling - Abstract
The Late Ordovician mass extinction (LOME) was the first global extinction with the destruction of 85 % of marine species. However, the cause of LOME is still controversial. Most studies attribute it to large-scale volcanism caused by global cooling or warming. Through analyzing the driving difference between global cooling and warming on large-scale magmatism, the perspective is intended to evoke a hot discussion on the cause of LOME. Did global cooling or warming trigger the LOME?
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- 2020
222. POWER TRANSMISSION LINE RECONSTRUCTION FROM SEQUENTIAL OBLIQUE UAV IMAGES
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Z. Wu, J. Xi, W. Yu, C. Zhu, Chen Chen, Bisheng Yang, W. Lei, H. Zhong, H. Wang, and Weidong Sun
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lcsh:Applied optics. Photonics ,Power transmission ,010504 meteorology & atmospheric sciences ,lcsh:T ,Computer science ,business.industry ,lcsh:TA1501-1820 ,Oblique case ,Scale (descriptive set theory) ,02 engineering and technology ,lcsh:Technology ,01 natural sciences ,Electric power transmission ,lcsh:TA1-2040 ,Transmission line ,Line (geometry) ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Computer vision ,Artificial intelligence ,lcsh:Engineering (General). Civil engineering (General) ,business ,0105 earth and related environmental sciences - Abstract
With the accelerated development of the global economy, the scale of UHV (Ultra High Voltage) large-capacity transmission lines has increased dramatically. Nevertheless, existing transmission line inspection methods rely on human inspectors detecting abnormal facilities from ground level or helicopters. Those methods not only require extremely high labor and equipment costs, but also are time-consuming. In this paper, a thin object 3D reconstruction method is proposed for the extraction of 3D structures of power lines from sequential oblique UAV images. The proposed method recovers the 3D structure of the power lines from three sequential images that depict the structure of power lines in 2D. Proposed method was tested in a typical transmission line corridor and the reconstructed results show the effectiveness of the proposed method.
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- 2020
223. Plate convergence in the Indo-Pacific region
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Weidong Sun, Renqiang Liao, Sai-Jun Sun, He Liu, Lipeng Zhang, and Congying Li
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geography ,geography.geographical_feature_category ,Subduction ,Pacific Plate ,Slab pull ,Transform fault ,Oceanography ,Plate tectonics ,Paleontology ,Oceanic crust ,Slab ,Oceanic basin ,Geology ,Water Science and Technology - Abstract
The Indo-Pacific convergence region is the best target to solve the two remaining challenges of the plate tectonics theory, i.e., subduction initiation and the driving force of plate tectonics. Recent studies proposed that the Izu-Bonin subduction initiation belongs to spontaneous initiation, which implies that it started from extension, followed by low angle subduction. Numerical geodynamic modeling suggests that the initiation of plate subduction likely occurred along a transform fault, which put the young spreading ridge in direct contact with old oceanic crust. This, however, does not explain the simultaneous subduction initiation in the west Pacific region in the Cenozoic. Namely, the subduction initiations in the Izu-Bonin- Mariana, the Aleutian, and the Tonga-Kermadec trenches are associated with oceanic crusts of different ages, yet they occurred at roughly the same time, suggesting that they were all triggered by a major change in the Pacific plate. Moreover, low angle subduction induces compression rather than extension, which requires external compression forces. Given that the famous Hawaiian-Emperor bending occurred roughly at the same time with the onset of westward subductions in the west Pacific, we propose that these Cenozoic subductions were initiated by the steering of the Pacific plate, which are classified as induced initiation. Induced subduction initiation usually occurs in young ocean basins, forming single-track subduction. The closures of Neo-Tethys Oceans were likely triggered by plumes in the south, forming northward subductions. Interestingly, the Indian plate kept on moving northward more than 50 Ma after the collision between the Indian and Eurasian continents and the break-off of the subducted oceanic slab attached to it. This strongly suggests that slab pull is not the main driving force of plate tectonics, whereas slab sliding is.
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- 2020
224. Evaluation of a deep learning‐based computer‐aided diagnosis system for distinguishing benign from malignant thyroid nodules in ultrasound images
- Author
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Tianjiao Liu, Chao Sun, Qing Chang, Qianqian Guo, Weidong Sun, Jinpeng Yao, Shao-Hang Zhang, Lijuan Niu, Yu-Kang Zhang, and Xi Wang
- Subjects
Thyroid nodules ,medicine.medical_specialty ,Local binary patterns ,CAD ,Sensitivity and Specificity ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Deep Learning ,0302 clinical medicine ,medicine ,Humans ,Diagnosis, Computer-Assisted ,Thyroid Nodule ,Ultrasonography ,Receiver operating characteristic ,Computers ,business.industry ,Deep learning ,Ultrasound ,General Medicine ,medicine.disease ,Feature (computer vision) ,Computer-aided diagnosis ,030220 oncology & carcinogenesis ,Radiology ,Artificial intelligence ,business - Abstract
Purpose Computer-aided diagnosis (CAD) systems assist in solving subjective diagnosis problems that typically rely on personal experience. A CAD system has been developed to differentiate malignant thyroid nodules from benign thyroid nodules in ultrasound images based on deep learning methods. The diagnostic performance was compared between the CAD system and the experienced attending radiologists. Methods The ultrasound image dataset for training the CAD system included 651 malignant nodules and 386 benign nodules while the database for testing included 422 malignant nodules and 128 benign nodules. All the nodules were confirmed by pathology results. In the proposed CAD system, a support vector machine (SVM) is used for classification and fused features which combined the deep features extracted by a convolutional neural network (CNN) with the hand-crafted features such as the histogram of oriented gradient (HOG), local binary patterns (LBP), and scale invariant feature transform (SIFT) were obtained. The optimal feature subset was formed by selecting these fused features based on the maximum class separation distance and used as the training sample for the SVM. Results The accuracy, sensitivity, and specificity of the CAD system were 92.5%, 96.4%, and 83.1%, respectively, which were higher than those of the experienced attending radiologists. The areas under the ROC curves of the CAD system and the attending radiologists were 0.881 and 0.819, respectively. Conclusions The CAD system for thyroid nodules exhibited a better diagnostic performance than experienced attending radiologists. The CAD system could be a reliable supplementary tool to diagnose thyroid nodules using ultrasonography. Macroscopic features in ultrasound images, such as the margins and shape of thyroid nodules, could influence the diagnostic efficiency of the CAD system.
- Published
- 2020
225. An Efficient Method of Hyperspectral Image Dimension Reduction Based on Low Rank Representation and Locally Linear Embedding
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Weidong Sun, Tingfa Xu, Teng Pan, and Jiqiang Luo
- Subjects
Materials science ,Rank (linear algebra) ,business.industry ,Dimensionality reduction ,Hyperspectral imaging ,Pattern recognition ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Image (mathematics) ,Discriminative model ,Control and Systems Engineering ,Materials Chemistry ,Ceramics and Composites ,Artificial intelligence ,Electrical and Electronic Engineering ,Representation (mathematics) ,business ,Linear embedding - Abstract
Hyperspectralimages (HSIs) can provide powerful spectral discriminative information for the land-covers, thus is widely used in classification and target detection. However, HSIs always suffer from...
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- 2020
226. An Efficient Compression Method of Hyperspectral Images Based on Compressed Sensing and Joint Optimization
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Weidong Sun, Tingfa Xu, Xiaolin Han, Teng Pan, and Jiqiang Luo
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010302 applied physics ,Materials science ,business.industry ,Hyperspectral imaging ,Data_CODINGANDINFORMATIONTHEORY ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Compression method ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Compressed sensing ,Control and Systems Engineering ,Compression (functional analysis) ,0103 physical sciences ,Materials Chemistry ,Ceramics and Composites ,Computer vision ,Artificial intelligence ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Joint (audio engineering) - Abstract
Compressed sensing provides the possibility of efficient compression of massive hyperspectral data. However, the existing methods often use the organization pattern of image blocks in sparse repres...
- Published
- 2020
227. Discovery of supercritical carbon dioxide in a hydrothermal system
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Xi-Luo Hao, Du Zengfeng, Weidong Sun, Lian Chao, Zhendong Luan, Lianfu Li, Bing Wang, Shichuan Xi, Lei Cao, Jun Yan, and Xin Zhang
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Multidisciplinary ,Supercritical carbon dioxide ,Chemistry ,010502 geochemistry & geophysics ,01 natural sciences ,Supercritical fluid ,Hydrothermal circulation ,Chemical engineering ,Abiogenesis ,Phase (matter) ,Seawater ,Earth (classical element) ,0105 earth and related environmental sciences ,Hydrothermal vent - Abstract
Supercritical CO2 appearing as bubbles in hydrothermal vents was identified in the south part of the Okinawa Trough using in situ Raman spectroscopy. Significantly, the N2 peak in supercritical CO2 is much larger than those in seawater and vent fluids, indicating that supercritical CO2 enriches N2 from the surrounding environment. Considering that the partial pressures of CO2 and N2 in the Earth’s proto-atmosphere were ~10–20 MPa, supercritical CO2 with high N2 was likely the dominant CO2 phase near the water-air interface in the early history of the Earth, which promoted the synthesis, pre-enrichment and preservation of amino acids and other organic matters that are essential to the origin of life.
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- 2020
228. Extremely light K in subducted low-T altered oceanic crust: Implications for K recycling in subduction zone
- Author
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Brenna Tuller-Ross, Haiyang Liu, Yilin Xiao, Ying-Yu Xue, Kun Wang, and Weidong Sun
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Basalt ,010504 meteorology & atmospheric sciences ,Mantle wedge ,Chemistry ,Geochemistry ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Mantle (geology) ,Phengite ,Geochemistry and Petrology ,Oceanic crust ,engineering ,Omphacite ,Eclogite ,Amphibole ,0105 earth and related environmental sciences - Abstract
In order to investigate the behavior of potassium (K) isotopes during metamorphic dehydration and to further constrain its implications for K recycling in the subduction zone, we measured K isotopic compositions of whole-rocks and separated minerals (phengite, omphacite, amphibole) from Sumdo eclogites, Tibet, using a recently established high-precision analysis method. Our data reveal that the δ41K (‰) of the whole-rock eclogites (−1.64 to −0.24) displays dramatically lower values than observed in fresh mid-ocean ridge basalts (MORB) (−0.43 ± 0.17) and altered MORB (−0.76 to −0.11). In addition, the δ41K values of eclogites show a positive correlation with both K2O contents and K/Nb ratios, which suggests that the low δ41K values were most likely caused by dehydration during subduction. Thus, isotopically heavy K may be released into the mantle wedge, while the light component is subducted into the deep mantle. Therefore, the K isotope systems have the potential to trace subducted crustal materials and to create heterogeneity within the mantle. Mineral separates from Sumdo eclogites are highly heterogeneous in K isotopic compositions, ranging from −0.98 to +0.23 in phengite, from −1.25 to −1.10 in omphacite and from −1.16 to −0.09 in amphibole. The K isotope fractionations between amphibole and phengite and between amphibole and omphacite vary from −0.30 to +0.25 and from −0.04 to +0.63, respectively, indicating K isotopic disequilibrium between amphibole and omphacite/phengite, which might result from the multistage growth of minerals during subduction metamorphism. However, generally phengites show heavier K isotopic compositions than the coexisting omphacite (Δ41Kphengite-amphibole = +0.25) and amphibole (Δ41Kphengite-amphibole = +0.03 ∼ +0.30, except TB193 is −0.25), which may imply that the K isotopic fractionation is controlled by the difference in coordination numbers of K between phengite (6) and omphacite (7 to 8)/amphibole (8).
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- 2020
229. Significant δ44/40Ca variations between carbonate- and clay-rich marine sediments from the Lesser Antilles forearc and implications for mantle heterogeneity
- Author
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Fang Liu, Zhaofeng Zhang, Hongli Zhu, Xiao-Yun Nan, Xin Li, Weidong Sun, Yajun An, Fang Huang, and Long Du
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010504 meteorology & atmospheric sciences ,Isotope ,Subduction ,Lithology ,Geochemistry ,Drilling ,010502 geochemistry & geophysics ,01 natural sciences ,Deep sea ,Mantle (geology) ,chemistry.chemical_compound ,chemistry ,Geochemistry and Petrology ,Carbonate ,Forearc ,Geology ,0105 earth and related environmental sciences - Abstract
Calcium isotopes can potentially be used to trace many geological processes. Characterizing the Ca isotopic compositions of marine sediments is a precondition for using Ca isotopes to trace the recycling of marine sediments into the mantle and mantle-derived rocks. The best way to achieve this goal is to investigate different types of marine sediments that are adjacent to subduction zones and would undergo subduction in the future. Here, we present high-precision Ca isotopic data for marine sediments from the Deep Sea Drilling Project (DSDP) Sites 543 and 144 along the Lesser Antilles forearc region, to constrain the Ca isotope signatures of marine sediments with various components and assess their possible effects on δ44/40Ca of the local mantle and arc lavas via subduction. Our results show that the δ44/40Ca values of these marine sediments vary from 0.10 to 1.21‰ and depend on lithology. Carbonate-rich sediments from Site 144 exhibit δ44/40Ca values in the range of 0.10–0.58‰ with a weighted average value of 0.36‰, which is ∼0.6‰ lower than that of the mantle. In comparison, δ44/40Ca of clay-rich sediments from Site 543 range from 0.79 to 1.21‰ with a mantle-like mean value of 0.96‰. The data obtained here suggest that carbonate- and clay-rich marine sediments differ significantly both in Ca isotopic compositions and CaO contents. Recycling of these sediments will result in different effects on the isotopic compositions of the local mantle and probably affect the local arc lavas. Specifically, carbonate-rich sediments from Site 144 with high CaO contents and light Ca isotopic compositions can alter the local mantle to lower δ44/40Ca signatures, which is expected in the southern Lesser Antilles arc lavas.
- Published
- 2020
230. Petrogenesis and tectonic implications of cambrian Nb-enriched I- and aluminous A-type granites in the North Qilian suture zone
- Author
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Yuxiao Chen, Tangfu Xiao, Shuguang Song, Weidong Sun, Kai Wu, and Ying Cui
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Subduction ,020209 energy ,Mantle metasomatism ,Geochemistry ,Geology ,02 engineering and technology ,010502 geochemistry & geophysics ,01 natural sciences ,Tectonics ,Continental margin ,0202 electrical engineering, electronic engineering, information engineering ,Suture (geology) ,0105 earth and related environmental sciences ,Petrogenesis - Abstract
Granitoids in active continental margins are probes of sub-arc magmatic processes and are crucial for the understanding of crust–mantle interaction during subduction. Here we report data for the mi...
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- 2020
231. Optimization and Purification of Levulinic Acid Extracted from Bagasse
- Author
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Weixi Liu, Wenjing Zheng, Shuai Chen, Weidong Sun, and Lei Liu
- Subjects
0106 biological sciences ,Chromatography ,Ion exchange ,Vacuum distillation ,04 agricultural and veterinary sciences ,Xylose ,01 natural sciences ,chemistry.chemical_compound ,Adsorption ,chemistry ,040103 agronomy & agriculture ,Levulinic acid ,0401 agriculture, forestry, and fisheries ,Hemicellulose ,Cellulose ,Bagasse ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
Levulinic acid (LA) is an important biomass-based chemical. The preparation of LA from bagasse is of great practical significance for the comprehensive and efficient utilization of biomass. Biomass bagasse is mainly composed of cellulose, hemicellulose, and lignin. The cellulose is mainly degraded to glucose, and hemicellulose is mainly degraded to xylose, with dilute acid treatment at high temperature. In this research, we produced the LA from bagasse with dilute acid treatment at high temperature. The influences of residence time (10–60 min), reaction temperature (170–240 °C), liquid-to-solid ratio (5:1–25:1 mL/g), and acid concentration (1–5%) on the synthesis of LA were investigated by statistical methods, achieving a maximum LA yield of 16.25%. Additionally, LA was isolated and extracted from bagasses hydrolysate by ion exchange and vacuum distillation. The adsorption capacity of different resins was determined and compared. The optimal resin to acquire better adsorption capacity was determined. The better adsorption capacity was obtained when the D301 resin was selected as the filter for ion exchange. The height-to-diameter rate, eluent flow rate, elution volume of ion exchange column were 10, 0.84 BV/h, 56.4 mL, respectively. The eluent was then distilled under vacuum, collecting the components at 130–140 °C. The total yield and purity of LA were 67.1% and 78%, respectively.
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- 2020
232. Calcium isotopic fractionation during plate subduction: Constraints from back-arc basin basalts
- Author
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Zhaofeng Zhang, Xin Li, Weidong Sun, Long Du, and Hongli Zhu
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010504 meteorology & atmospheric sciences ,Lau Basin ,Subduction ,Partial melting ,Geochemistry ,010502 geochemistry & geophysics ,01 natural sciences ,Mantle (geology) ,Geochemistry and Petrology ,Back-arc basin ,Slab ,Igneous differentiation ,Metasomatism ,Geology ,0105 earth and related environmental sciences - Abstract
Subduction related metasomatism has been proposed to be one of the most important processes that may cause Ca isotopic heterogeneities in the mantle. Back-arc basin basalts (BABBs) affected by different contributions of subducted materials have various geochemical compositions ranging from MORB-like to arc-like, so that they are ideal media to investigate the behavior of Ca isotopes during plate subduction. Here we report Ca isotopic compositions of a series of BABBs from the Lau Basin, Woodlark Basin and Coriolis Troughs in the southwestern Pacific. Our results show that δ44/40Ca of all the BABBs exhibit a narrow range of 0.73 ± 0.07 to 0.89 ± 0.06‰ with an average of 0.80 ± 0.08‰ (2SD, N = 21), which are lower than the estimated value of the Bulk Silicate Earth (BSE, 0.94 ± 0.05‰), but are similar to that of MORBs reported in the literature (0.83 ± 0.11‰, 2SD, N = 21). Even though the mantle sources of BABBs studied here have been influenced by various amounts of slab-derived fluids and/or sediments, there is no systematic variation of δ44/40Ca with indicators of subduction contributions (e.g., Ce/Pb, Nb/U, Ba/La, Th/Yb, 87Sr/86Sr and 143Nd/144Nd). This suggests that either there is no Ca isotopic discrepancy between subducted components and mantle, and/or the amount of Ca that is transferred from the subducting Pacific slab to the studied BABB mantle sources is insignificant. Water depths at which subducting sediments were deposited control the components of marine sediments that may be subducted, which in turn determine how subduction affects Ca isotopic composition of the mantle. Because the southwestern Pacific has deeper water depths than the carbonate compensation depth, pelagic clays dominate the contribution from the subducted slab rather than carbonates, which leads to the negligible Ca isotopic fractionation during subduction along these trenches. The lack of correlations of δ44/40Ca with geochemical indicators of magma differentiation (e.g., MgO, CaO/Al2O3, Sr/Nd, Eu/Eu*) suggests that intermediate-mafic magma differentiation has insignificant effects on Ca isotopic compositions of BABBs. Therefore, we conclude that the observed offset of δ44/40Ca (∼0.14‰) between the mantle and BABBs studied here should be primarily controlled by Ca isotopic fractionation during partial melting without significant contributions from subducted materials.
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- 2020
233. High oxygen fugacity magma: implication for the destruction of the North China Craton
- Author
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Ming-Xing Ling, Zhe-Kun Zhang, Weidong Sun, Sai-Jun Sun, and Lipeng Zhang
- Subjects
Craton ,geography ,geography.geographical_feature_category ,Subduction ,Mantle wedge ,Geochemistry and Petrology ,Lithosphere ,Magmatism ,Geochemistry ,Intraplate earthquake ,Mantle (geology) ,Geology ,Zircon - Abstract
The mechanism of lithospheric removal and destruction of the North China Craton (NCC) has been hotly debated for decades. It is now generally accepted that the subduction of the (Paleo)-Pacific plate played an important role in this process. However, how the plate subduction contributed to the craton destruction remains unclear. Here we report high oxygen fugacity (fO2) characteristics of the Yunmengshan granite, e.g., hematite–magnetite intergrowth supported by zircon Ce4+/Ce3+ ratios and apatite Mn oxygen fugacity indicator. High fO2 magmas are widely discovered in Late Mesozoic (160–130 Ma) adakitic rocks in central NCC. The origin of high fO2 magma is likely related to the input of the “oxidized mantle components”, which shows a close connection between plate subduction and destruction of the craton. The research area is ~ 1500 km away from the current Pacific subduction zone. Considering the back-arc extension of Japan Sea since the Cretaceous, this distance may be shortened to ~ 800 km, which is still too far for normal plate subduction. Ridge subduction is the best candidate that was responsible for the large scale magmatism and the destruction of the NCC. Massive slab-derived fluids and/or melts were liberated into an overlying mantle wedge and modified the lithospheric mantle. Rollback of the subducting plate induced the large-scale upwelling of asthenospheric mantle and triggered the formation of extensive high fO2 intraplate magmas.
- Published
- 2020
234. Investigation of an oceanic plateau formation and rifting initiation model implied by the Caroline Ridge on the Caroline Plate, western Pacific
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Weidong Sun, Yongliang Bai, Dongdong Dong, Zhengyi Zhang, and Guangxu Zhang
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Rift ,020209 energy ,Geology ,Oceanic plateau ,02 engineering and technology ,010502 geochemistry & geophysics ,01 natural sciences ,Seafloor spreading ,Paleontology ,Lithosphere ,Hotspot (geology) ,0202 electrical engineering, electronic engineering, information engineering ,0105 earth and related environmental sciences - Abstract
The rifting of oceanic plateaus is an important mechanism for initiating lithospheric break-up and subsequent seafloor spreading. In this study, we present the latest multichannel seismic data investigating the Caroline Ridge and provide one of the typical cases for initial oceanic plateau evolution. We reveal that a smooth basement reflector (R2), as the top of the lava flows, is subparallel to the sediments with horizontal seismic reflections over the surface of the Caroline Ridge. Thick layer-parallel lava flows beneath the R2 appear within the crust. Large seamounts in the Sorol Trough possess abundant saucer-shaped intracrustal reflectors, and the overlying sediments were destroyed by intrusive bodies. The overlying sedimentary sequences, basement, and thick lava flows on the Caroline Ridge flanks were faulted by opposing normal fault sets, and the eruptions of the seamounts deformed the strata. A widespread bright horizontal reflector (R1), as an unconformity inside the Caroline Ridge sediments, truncates the lower tilted sediment layers and is itself cut by normal faults in the flank strata. Furthermore, we propose that subaerial lava flows extended laterally from the hotspot magmatism localizing in the Sorol Trough and led to Caroline Ridge formation. The initial rifting of the Caroline Ridge occurred during the Early-Middle Miocene. Limited volcanoes concentrate only in the Sorol Trough due to the attenuated thermal effect. It is suggested that dome uplifting and far-field force could have jointly caused initial rifting process of the Caroline Ridge.
- Published
- 2020
235. A Ni-foam-structured MoNi4–MoOx nanocomposite catalyst for hydrogenation of dimethyl oxalate to ethanol
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Jian Zhu, Song Wang, Guofeng Zhao, Weidong Sun, Yong Lu, and Ye Liu
- Subjects
Ethanol ,Methyl acetate ,Spinel ,Metals and Alloys ,Nanocomposite catalyst ,General Chemistry ,engineering.material ,Catalysis ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Ceramics and Composites ,engineering ,Selectivity ,Dimethyl oxalate ,Ethylene glycol ,Nuclear chemistry - Abstract
We report a Ni-foam-structured MoNi4-MoOx nanocomposite catalyst derived from NiMoO4 spinel in situ grown on Ni-foam, which is highly active, selective (>93%) and stable for the gas-phase hydrogenation of dimethyl oxalate to ethanol. Such a reaction proceeds mainly through ethylene glycol formation, whereas a pathway through methyl acetate (MA) formation also occurs. Catalyst activity and selectivity are primarily governed by the MoNi4 nanoalloy but can be further improved by an MoOx modifier, due to the synergistic MoNi4-MoOx interaction that markedly promotes the MA hydrogenation to EtOH.
- Published
- 2020
236. Bright and efficient red emitting electroluminescent devices fabricated from ternary europium complexes
- Author
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José Diogo L. Dutra, Weidong Sun, Rashid Ilmi, Wai Yeung Wong, Liang Zhou, Paul R. Raithby, Willyan F. Oliveira, and Muhammad S. Khan
- Subjects
Materials science ,Dopant ,Doping ,Analytical chemistry ,chemistry.chemical_element ,General Chemistry ,Electroluminescence ,Red Color ,chemistry ,Materials Chemistry ,Quantum efficiency ,Europium ,Ternary operation ,Common emitter - Abstract
The photophysical properties of two previously synthesized, highly efficient, bright red emitting complexes [Eu(btfa)3DPEPO] (CIE, 0.672; 0.326) (Eu-1) and [Eu(nta)3DPEPO] (CIE, 0.673; 0.326) (Eu-2) (btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione, nta = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione and DPEPO = bis(2-(diphenylphosphino)phenyl)ether oxide) are reported. The complexes have been used as dopants to fabricate several single and double emitting layer (EML) electroluminescent (EL) devices. At the optimum doping concentration of 4 wt%, the single EML device of Eu-1 exhibited a pure red color with an external quantum efficiency (EQE) of 2.9% and a maximum brightness (B) = 1320 cd m−2, maximum current efficiency (ηc) = 4.08 cd A−1, maximum power efficiency (ηp) = 3.37 lm W−1 with a very low turn-on voltage (Vturn-on) = 3.8 V. Importantly, the single EML device of Eu-2 at the optimum doping concentration exhibited pure red EL with EQE of 6.0% with the best EL performance: B = 2108 cd m−2, ηc = 8.45 cd A−1, and ηp = 6.98 lm W−1 at a very low Vturn-on = 3.5 V. The performances of this device are among the best reported for devices incorporating a europium complex as a red emitter. Furthermore, the EL performances were achieved at the current density of 10 mA cm−2, thereby alleviating a serious efficiency roll-off as a major obstacle to the development of Eu-complex based EL devices.
- Published
- 2020
237. Monochromatic red electroluminescence from a homodinuclear europium(<scp>iii</scp>) complex of a β-diketone tethered by 2,2′-bipyrimidine
- Author
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Nawal K. Al-Rasbi, Weidong Sun, Wai Yeung Wong, Paul R. Raithby, Muhammad S. Khan, Liang Zhou, José Diogo L. Dutra, Rashid Ilmi, and Peng Cheng Qian
- Subjects
Photoluminescence ,Materials science ,Analytical chemistry ,chemistry.chemical_element ,Quantum yield ,General Chemistry ,Crystal structure ,Electroluminescence ,chemistry ,Materials Chemistry ,Quantum efficiency ,Europium ,Single crystal ,Coordination geometry - Abstract
A new homodinuclear complex [Eu(btfa)3]2bpm (1) was synthesized incorporating 4,4,4-trifluoro-1-phenyl-1,3-butanedione (btfa) as the primary and 2,2′-bipyrimidine (bpm) as the auxiliary ligand. The complex was characterized by analytical and spectroscopic techniques, with special emphasis on the crystal structure and photoluminescence (PL) properties, both experimentally and theoretically. Single crystal X-ray diffraction (SCXRD) analysis reveals that the two Eu(III) ions in 1 are eight coordinate, where the bpm behaves as a N4 donor linking the two Eu(III) ions symmetrically. Each Eu(III) ion displays a distorted square antiprismatic (DSAP, D4d) coordination geometry. Complex 1 displayed bright red emission with (CIE)x,y color coordinates = 0.670; 0.330 and an absolute photoluminescence quantum yield (PLQY) of 54.4%. The theoretical intensity parameters (Ω2 and Ω4), radiative (AR) and non-radiative (ANR) decay rates, intrinsic quantum yield (QEuEu), sensitization efficiency (ηsen) and PLQY were assessed using the LUMPAC software and showed very good agreement with the experimental values. Based on these, an energy transfer (ET) mechanism is proposed and discussed. Moreover, 1 was used as an emitter to fabricate single- and double-emitting layer (EML) red-emitting electroluminescent devices. Double-EML device at the optimum doping concentration of 4.0 wt% displayed impressive EL performances, brightness (B) = 812 cd m−2, maximum current efficiency (ηc) = 3.97 cd A−1, maximum power efficiency (ηp) = 3.89 lm W−1, and external quantum efficiency (EQE) = 2.8% at very low Vturn-on = 3.2 V with (CIE)x,y = 0.662, 0.321 which is close to the standard red color recommended by NTSC (0.67, 0.33).
- Published
- 2020
238. Pure-blue fluorescent organic light-emitting diodes by co-doping a supplementary host material into a light-emitting layer as an electron transport ladder
- Author
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Zhenzhen Li, Shuaibing Li, Liang Zhou, Qi Zhu, Ruixia Wu, Hongjie Zhang, and Weidong Sun
- Subjects
Materials science ,business.industry ,Doping ,General Chemistry ,Electroluminescence ,Triphenylamine ,Fluorescence ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,OLED ,Optoelectronics ,Quantum efficiency ,business ,Electrical efficiency ,Common emitter - Abstract
In this study, an efficient device design strategy in improving the performances of blue fluorescent electroluminescence was demonstrated by co-doping 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole (CzSi) into a light-emitting layer (EML) as an electron transport ladder. 9,10-Bis[4-(6-methylbenzothiazol-2-yl)phenyl]anthracene (DBzA) and 4,4′,4′′-tris(carbazol-9-yl)triphenylamine (TcTa) were utilized as the emitter and the main host material, respectively. Compared with the device without CzSi, the performances of the co-doped device were improved effectively because of the well-matched energy levels and excellent electron transport ability of CzSi, which facilitated the injection of electrons and thus balanced the distribution of carriers. The feasibility of this device design strategy was demonstrated by investigating single-carrier devices, transient electroluminescent (EL) spectra and normalized EL spectra. Finally, the optimal pure blue fluorescent device realized a maximum brightness, current efficiency, power efficiency and external quantum efficiency (EQE) of up to 28 009 cd m−2, 7.51 cd A−1, 7.60 lm W−1 and 6.8%, respectively. Even at a high brightness of 1000 cd m−2, current efficiency and EQE as high as 6.21 cd A−1 and 5.6%, respectively, can still be retained by the same device.
- Published
- 2020
239. The Late Mesozoic granodiorite and polymetallic mineralization in southern Anhui Province, China: A perspective from apatite geochemistry
- Author
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Weidong Sun, Yu Wang, Jiancheng Xie, and Lin Qian
- Subjects
Mineralization (geology) ,Electron probe microanalysis ,010504 meteorology & atmospheric sciences ,Fluorapatite ,lcsh:QE1-996.5 ,Geochemistry ,Geology ,Electron microprobe ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Apatite ,lcsh:Geology ,Mineral exploration ,Geophysics ,Geochemistry and Petrology ,visual_art ,visual_art.visual_art_medium ,Mesozoic ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
The region of southern Anhui Province (SAP) is one of Late Mesozoic magmatic belts and copper-molybdenum-gold-tungsten polymetallic ore districts in China, but the relationship of polymetallic mineralization and related granodiorite remains unclear. Previous studies indicate that apatite can be an indicator for magmatic evolution and mineral exploration. In this study, apatites from the SAP ore-bearing granodiorites were investigated using observations from the electron microscope, electron probe microanalysis (EPMA), laser-ablation inductively-coupled plasma-mass spectrometry (LA-ICP-MS). The studied apatite samples identified as fluorapatite, show high F (2.69–4.13 wt.%) and low Cl contents (mainly
- Published
- 2019
240. An A1-type granite that borders A2-type: insights from the geochemical characteristics of the Zongyang A-type granite in the Lower Yangtze River Belt, China
- Author
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Lipeng Zhang, Xiao-Yan Jiang, Weidong Sun, Kai Wu, Xiaoping Xia, and Jin-Cheng Luo
- Subjects
020209 energy ,Geochemistry ,Geology ,02 engineering and technology ,010502 geochemistry & geophysics ,01 natural sciences ,0202 electrical engineering, electronic engineering, information engineering ,Yangtze river ,Mesozoic ,A-type granite ,China ,0105 earth and related environmental sciences ,Petrogenesis - Abstract
Mesozoic A-type granites are widely distributed in the Lower Yangtze River Belt (LYRB) in China, but their petrogenesis and geodynamic settings are unresolved. Here, we describe geochronological an...
- Published
- 2019
241. Improved method for aging assessment of winding hot-spot insulation of transformer based on the 2-FAL concentration in oil
- Author
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Cheng Zhidong, Firuz Zare, Lijun Yang, Weidong Sun, and Yuandi Lin
- Subjects
Materials science ,Moisture ,Chain scission ,020209 energy ,020208 electrical & electronic engineering ,Energy Engineering and Power Technology ,Improved method ,02 engineering and technology ,law.invention ,Linear relationship ,Chemical marker ,law ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Cellulose insulation ,Electrical and Electronic Engineering ,Composite material ,Mineral oil ,Transformer ,medicine.drug - Abstract
2-furfuraldehyde (2-FAL) is widely accepted as a chemical marker to indicate the degradation of cellulose insulation in oil-impregnated transformers. However, the application of 2-FAL in the aging diagnosis of transformers in operation is ineffective. The excessive dispersion of 2-FAL concentration measured in transformers is caused by many influence factors. In addition, the 2-FAL concentration in oil cannot indicate the aging of the most serious point given the temperature distribution along the winding height, that is, the insulation at the hot spot of a winding. To optimize the assessment, an improved method for the hot-spot insulation assessment based on the 2-FAL concentration in oil is proposed in this work. The 2-FAL generation in cellulose chain scission is firstly analyzed theoretically, and a new linear relationship between ( 1 / D P t - 1 / D P 0 ) and 2-FAL total generation is obtained. Moreover, the 2-FAL partitioning between an insulation paper and mineral oil influenced by temperature, moisture, and aging status in total is considered. Second, by considering the linear relationship and the 2-FAL partitioning, an equation between the insulation at hot-spot temperature and the 2-FAL concentration in oil is established for the thermal aging under unequal temperature distribution condition. Finally, to verify the proposed method, a testing platform is introduced to conduct the thermal aging experiment with temperature gradients. The proposed method demonstrates better assessment results than the conventional thermal aging test at constant temperature.
- Published
- 2019
242. Oxidative Dehydrogenation of Ethane: Superior Nb2O5-NiO/Ni-Foam Catalyst Tailored by Tuning Morphology of NiO-Precursors Grown on a Ni-Foam
- Author
-
Guofeng Zhao, Ye Liu, Yong Lu, Weidong Sun, and Zhiqiang Zhang
- Subjects
0301 basic medicine ,Nanostructure ,Ethylene ,Materials science ,02 engineering and technology ,Article ,Catalysis ,Nanomaterials ,03 medical and health sciences ,chemistry.chemical_compound ,Nano ,Dehydrogenation ,lcsh:Science ,Nanosheet ,Multidisciplinary ,Non-blocking I/O ,Organic Reaction ,021001 nanoscience & nanotechnology ,030104 developmental biology ,chemistry ,Chemical engineering ,lcsh:Q ,0210 nano-technology ,Selectivity - Abstract
Summary Large-scale shale gas exploitation greatly enriches ethane resources, making the oxidative dehydrogenation of ethane to ethylene quite fascinating, but the qualified catalyst with unique combination of enhanced activity/selectivity, enhanced heat transfer, and low pressure drop presents a grand challenge. Herein, a high-performance Nb2O5-NiO/Ni-foam catalyst engineered from nano- to macroscale for this reaction is tailored by finely tuning the performance-relevant Nb2O5-NiO interaction that is strongly dependent on NiO-precursor morphology. Three NiO-precursors of different morphologies (clump, rod, and nanosheet) were directly grown onto Ni-foam followed by Nb2O5 modification to obtain the catalyst products. Notably, the one from the NiO-precursor of nanosheet achieves the highest ethylene yield, in nature, because of markedly diminished unselective oxygen species due to enhanced interaction between Nb2O5 and NiO nanosheet. An advanced catalyst is developed by further thinning the NiO-precursor nanosheet, which achieves 60% conversion with 80% selectivity and is stable for at least 240 h., Graphical Abstract, Highlights • A series of Nb2O5-NiO/Ni-foam catalysts are developed for the ODE reaction • Catalysts are obtained by Nb2O5 modification of NiO-precursors grown onto Ni-foam • Thinning NiO-precursors dramatically improves the ethylene selectivity • Non-selective O2- species are markedly reduced with enhanced Nb2O5-NiO interaction, Catalysis; Organic Reaction; Nanomaterials; Nanostructure
- Published
- 2019
243. Nanoporous Ni3P Evolutionarily Structured onto a Ni Foam for Highly Selective Hydrogenation of Dimethyl Oxalate to Methyl Glycolate
- Author
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Jian Zhu, Guofeng Zhao, Yong Lu, Tong Zhu, Weidong Sun, Wei Hu, Cuiyu Li, and Liqun Cao
- Subjects
Materials science ,Nanoporous ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Adsorption ,chemistry ,General Materials Science ,0210 nano-technology ,Selectivity ,Dimethyl oxalate ,Ethylene glycol ,Glycolic acid ,Syngas - Abstract
Methyl glycolate (MG) is a versatile platform molecule to produce numerous important chemicals and materials, especially new-generation biocompatible and biodegradable poly(glycolic acid). In principle, it can be massively produced from syngas (CO + H2) via gas-phase hydrogenation of CO-derived dimethyl oxalate (DMO), but the groundbreaking catalyst represents a grand challenge. Here, we report the discovery of a Ni-foam-structured nanoporous Ni3P catalyst, evolutionarily transformed from a Ni2P/Ni-foam engineered from nano- to macro-scale, being capable of nearly fully converting DMO into MG at >95% selectivity and stable for at least 1000 h without any sign of deactivation. As revealed by kinetic experiments and theoretical calculations, in comparison with Ni2P, Ni3P achieves a higher surface electron density that is favorable for MG adsorption in a molecular manner rather than in a dissociative manner and has much higher activation energy for MG hydrogenation to ethylene glycol (EG), thereby markedly suppressing its overhydrogenation to EG.
- Published
- 2019
244. Global atmospheric oxygen variations recorded by Th/U systematics of igneous rocks
- Author
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Robert E. Zartman, Weidong Sun, He Liu, and Trevor Ireland
- Subjects
Multidisciplinary ,010504 meteorology & atmospheric sciences ,Subduction ,Proterozoic ,Archean ,Great Oxygenation Event ,Th/U systematics ,Neoproterozoic Oxygenation Event ,Geochemistry ,010502 geochemistry & geophysics ,01 natural sciences ,arc igneous rocks ,Atmosphere ,Igneous rock ,Earth, Atmospheric, and Planetary Sciences ,Oceanic crust ,Physical Sciences ,Sedimentary rock ,Great Oxidation Event ,Geology ,0105 earth and related environmental sciences - Abstract
Significance Scientists have been working on the dating of atmospheric oxygenation in Earth’s history for decades. However, most previous studies relied on evidence from sedimentary rocks. Here, we show that igneous rocks can also be linked with surface oxidation by a key geological process: plate subduction. We here make an attempt to apply the Th/U of worldwide arc igneous rocks as an indicator for the timing of atmospheric oxygenation over the Earth’s history. The results are coincident with the previously defined Great Oxidation Event and Neoproterozoic Oxygenation Event., Atmospheric oxygen has evolved from negligible levels in the Archean to the current level of about 21% through 2 major step rises: The Great Oxidation Event (GOE) in the early Proterozoic and the Neoproterozoic Oxygenation Event (NOE) during the late Proterozoic. However, most previous methods for constraining the time of atmospheric oxygenation have relied on evidence from sedimentary rocks. Here, we investigate the temporal variations of the Th/U of arc igneous rocks since 3.0 billion y ago (Ga) and show that 2 major Th/U decreases are recorded at ca. 2.35 Ga and ca. 0.75 Ga, coincident with the beginning of the GOE and NOE. The decoupling of U from Th is predominantly caused by the significant rise of atmospheric oxygen. Under an increasingly oxidized atmosphere condition, more uranium in the surface environment became oxidized from the water-insoluble U4+ to the water-soluble U6+ valance and incorporated in the sea water and altered oceanic crust. Eventually, the subduction of this altered oceanic crust produced the low-Th/U signature of arc igneous rocks. Therefore, the sharp decrease of Th/U in global arc igneous rocks may provide strong evidence for the rise of atmospheric oxygen. We suggest that the secular Th/U evolution of arc igneous rocks could be an effective geochemical indicator recording the global-scale atmospheric oxygen variation.
- Published
- 2019
245. Ca-Sr isotope and chemical evidence for distinct sources of carbonatite and silicate mantle metasomatism
- Author
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Hongli Zhu, Dmitri A. Ionov, Long Du, Zhaofeng Zhang, Weidong Sun, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)
- Subjects
Peridotite ,010504 meteorology & atmospheric sciences ,Chemistry ,Dolomite ,Geochemistry ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,010502 geochemistry & geophysics ,01 natural sciences ,Mantle (geology) ,Silicate ,chemistry.chemical_compound ,13. Climate action ,Geochemistry and Petrology ,[SDU]Sciences of the Universe [physics] ,[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry ,Carbonatite ,Xenolith ,Metasomatism ,Mafic ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences - Abstract
Enrichments in light REE without concomitant enrichments in high-field-strength elements in mantle peridotites are usually attributed to inputs from carbonate-rich melts and referred to as ‘carbonatite’ metasomatism as opposed to interaction with evolved silicate melts. Alternatively, both enrichment types are ascribed to percolating volatile-bearing mafic liquids whose chemical signatures evolve from ‘silicate’ to ‘carbonatite’. Here we compare these models for peridotites in which these enrichment types are combined, as may be common in the mantle. We report new Ca-Sr-Nd isotope and chemical data for lherzolite and harzburgite xenoliths from Spitsbergen that were metasomatized, first, by silicate, then by carbonate-rich melts that formed carbonate-bearing pockets replacing earlier minerals. Seven crushed samples were treated with acetic acid that dissolved carbonates formed in the latest event, but not silicates. The leachates (acid-removed carbonates making up 0.6–1.4% of total sample mass) contain much more Sr than the residues after leaching (277–2923 vs. 16–60 ppm), have a greater overall 87Sr/86Sr range (0.7049–0.7141 vs. 0.7036–0.7055) and higher 87Sr/86Sr in each sample than the residues. The leachates have lower δ44/40Ca range (0.17–0.68‰) than the residues (0.78–1.00‰), as well as lower δ44/40Ca than the residues in all samples but one. By and large, the carbonates are out of Ca-Sr isotope equilibrium with the host peridotites implying that the older silicate and younger carbonatite metasomatism were produced by different parental melts, thus supporting the existence of distinctive carbonate-rich metasomatic media in the lithospheric mantle, possibly including recycled materials. The δ44/40Ca in the leachates (i.e. carbonates, 0.17–0.68‰) are well below bulk silicate Earth (BSE) estimates (0.94 ± 0.05‰) and δ44/40Ca in non-metasomatized melt-depleted mantle. Yet, δ44/40Ca in the non-leached whole rock (WR) carbonate-bearing samples (0.75–0.95‰) fall within, or are only slightly lower than, the BSE range. The 87Sr/86Sr range in these WR samples (0.7030–0.7112) includes very high values for peridotites with large aggregates of dolomite and Mg-calcite. It appears that both carbonatite and silicate metasomatism may produce δ44/40Ca values lower than the BSE such that Ca-isotope data cannot robustly tell apart these two enrichment types, yet carbonatite metasomatism may yield the lowest δ44/40Ca. Carbonates, even at small mass fractions, are significant hosts of Sr in the WR Spitsbergen peridotites (8–51 wt.% of Sr mass) because of very high Sr concentrations, but add little to WR Ca balance (3–12 wt.%). As a result, high Sr content and 87Sr/86Sr ratios may be indices (though not definitive proofs) of carbonatite metasomatism in mantle rocks.
- Published
- 2021
246. Algorithmic Research on Offensive Tactics Law under the Statistical Characteristics of Basic Physical Fitness Data
- Author
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Tianbo Yu, Lei Ji, Donghui Dai, Rui Sun, Xiaolong Wang, Qi Li, Peng Cheng, and Weidong Sun
- Published
- 2021
247. A comparative study of two-step anodization with one-step anodization at constant voltage
- Author
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Chengyuan Li, Huipeng Zeng, Shaoyu Zhang, Yuxin Dan, Yishan Lu, Ye Song, and Weidong Sun
- Subjects
Electronic current ,Nanotube ,Materials science ,business.industry ,Anodizing ,Mechanical Engineering ,Two step ,Bioengineering ,One-Step ,General Chemistry ,Electrolyte ,Anode ,Mechanics of Materials ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,Porosity ,business - Abstract
Two-step anodization has been widely used because it can produce highly self-organized anodic TiO2 nanotubes, but the differences in morphology and current-time curve of one-step anodization and two-step anodization are rarely reported. Here, one-step anodization and two-step anodization were conducted at different voltages. By comparing the FESEM image of anodic TiO2 nanotubes fabricated by one-step anodization and two-step anodization, it was found that the variation of morphology characteristics is same with voltage. The distinction of morphology and current-time curve between one-step anodization and two-step anodization at the same voltage were analyzed: the nanotube average growth rate and porosity of two-step anodization are greater than that of one-step anodization. In the current-time curve, the duration of stage I and stage II in two-step anodization are significantly shorter than one-step anodization. The traditional field-assisted dissolution theory cannot explain the three stages of the current-time curves and their physics meaning under different voltages in the same fluoride electrolyte. Here, the distinction between one-step anodization and two-step anodization was clarified successfully by the theories of ionic current and electronic current and oxygen bubble mould.
- Published
- 2022
248. Self-structured monolithic TiO2-Mn2O3-Na2WO4-foam catalyst towards efficient oxidative coupling of methane
- Author
-
Guofeng Zhao, Jincun Liu, Jiaqi Si, Jiayong Ni, Weidong Sun, Ye Liu, and Yong Lu
- Subjects
Fuel Technology ,General Chemical Engineering ,Organic Chemistry ,Energy Engineering and Power Technology - Published
- 2022
249. Genesis of Chaoshan skarn Au deposit, Tongling, eastern China: Insights from mineral geochemistry
- Author
-
Jiancheng Xie, Xin Zhang, Shan Huang, Likai Ge, Quanzhong Li, and Weidong Sun
- Subjects
Geochemistry and Petrology ,Economic Geology - Published
- 2022
250. Dynamic processes of upper plate deformation at the New Guinea Trench
- Author
-
Zhengyi Zhang, Xiwu Luan, Fanfan Tian, Weimin Ran, Liang Zhang, Dongdong Dong, and Weidong Sun
- Subjects
Geophysics ,Earth-Surface Processes - Published
- 2022
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