检索结果-南通市图书馆

High-resolution Moho depth and V_(p)/V_(s) ratio distributions in northeast China from joint inversion of receiver functions and gravity data and their geological implications

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2023年第7期66卷 1569-1582页

作者： Aowei HAO Haijiang ZHANG Shoucheng HAN wenliang xu School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Anhui Mengcheng National Geophysical Observatory Mengcheng 233527China Xi’an Mineral Resources Survey Center of China Geology Survey Xi’an 710100China College of Earth Sciences Jilin UniversityChangchun 130061China

In this study,high-resolution Moho depth and average crustal V_(p)/V_(s) ratio distributions in northeast China were obtained through joint inversion of receiver functions and gravity data.The new joint inversion method comprehensively considers the complementary imaging strengths of the receiver functions in the vertical direction and the gravity data in the lateral direction.To a certain extent,it can reduce the adverse effects of the receiver function data caused by the sedimentary layers of the basin,the inclination of the Moho,and the structure heterogeneity below the station.In preprocessing the receiver function data,a regularized virtual station network was constructed using the teleseismic receiver function waveform reconstruction method to improve the overall spatial resolution.To filter the gravity data,the velocity structure-guided gravity filtering method and gravity upward continuation were used for the shallower region above the Moho and the deeper region below the lithosphere,respectively.The newly obtained model shows that the Moho depths of the Hailar Basin,Erlian Basin,Sanjiang Basin,and Bohai Bay Basin are slightly shallower than those of the surrounding areas,while the Moho depths of the Greater Xing’an Range,Lesser Xing’an Range,and Zhangguangcai Range are slightly deeper.Compared with previous results,the refined Moho depth distribution obtained in this study has a better correspondence with topographic relief and basin boundaries,and the contrast is more evident across the north-south gravity gradient lineament(NSGL).In the eastern part of the Songliao Basin,the Moho is relatively shallow,and there is a high V_(p)/V_(s) ratio,which may have been caused by the intrusion of hot mantle materials into the crust induced by lateral extension of the Songliao Basin.The high V_(p)/V_(s) ratio of the crust below the Changbaishan volcanic area implies the existence of partial melting in the crust caused by upwelling hot mantle materials.

关键词： Receiver functions Gravity Moho depth Vp/Vs ratio Northeast China

Two-photon live imaging of direct glia-to-neuron conversion in the mouse cortex

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第8期19卷 1781-1788页

作者： Zongqin Xiang Shu He Rongjie Chen Shanggong Liu Minhui Liu Liang xu Jiajun Zheng Zhouquan Jiang Long Ma Ying Sun Yongpeng Qin Yi Chen Wen Li Xiangyu Wang Gong Chen wenliang Lei Guangdong-Hong Kong-Macao Institute of CNS Regeneration(GHMICR) Jinan UniversityGuangzhouGuangdong ProvinceChina Department of Neurosurgery The First Affiliated HospitalJinan UniversityGuangzhouGuangdong ProvinceChina Laboratory for Neuroimmunology in Health and Diseases Guangzhou First People’s HospitalSchool of MedicineSouth China University of TechnologyGuangzhouGuangdong ProvinceChina VIB-KU Leuven Center for Brain&Disease Research LeuvenFlemish RegionBelgium

Over the past decade,a growing number of studies have reported transcription factor-based in situ reprogramming that can directly conve rt endogenous glial cells into functional neurons as an alternative approach for n euro regeneration in the adult mammalian central ne rvous system.Howeve r,many questions remain regarding how a terminally differentiated glial cell can transform into a delicate neuron that forms part of the intricate brain circuitry.In addition,concerns have recently been raised around the absence of astrocyte-to-neuron conversion in astrocytic lineage-tra cing mice.In this study,we employed repetitive two-photon imaging to continuously capture the in situ astrocyte-to-neuron conversion process following ecto pic expression of the neural transcription factor NeuroD1 in both prolife rating reactive astrocytes and lineage-tra ced astrocytes in the mouse cortex.Time-lapse imaging over several wee ks revealed the ste p-by-step transition from a typical astrocyte with numero us short,tapered branches to a typical neuro n with a few long neurites and dynamic growth cones that actively explored the local environment.In addition,these lineage-converting cells were able to migrate ra dially or to ngentially to relocate to suitable positions.Furthermore,two-photon Ca2+imaging and patch-clamp recordings confirmed that the newly generated neuro ns exhibited synchronous calcium signals,repetitive action potentials,and spontaneous synaptic responses,suggesting that they had made functional synaptic connections within local neural circuits.In conclusion,we directly visualized the step-by-step lineage conversion process from astrocytes to functional neurons in vivo and unambiguously demonstrated that adult mammalian brains are highly plastic with respect to their potential for neuro regeneration and neural circuit reconstruction.

关键词： astrocyte-to-neuron conversion Ca2+imaging direct lineage conversion glia astrocyte in vivo reprogramming lineage-tracing mice NeuroD1 neuron two-photon imaging

Pore defects in a nickel-based superalloy with high Ti content

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2022年第4期32卷 456-462页

作者： Puying Shi wenliang xu Baoquan Fu Jin Liu Jianing Zhang Kaixuan Wang Xianghong Liu Western Superconducting Technologies Co. Ltd. School of Mechanical Engineering Xi'an Jiaotong University

Pores are uncommon defects in superalloy bars, which deserve to be investigated. In this work, a type of pore defect within GH4710 nickel-based superalloy was investigated by 3D X-ray imaging method combined with metallographic analysis. 3D X-ray imaging was used for locating and visualizing the defects in the alloy. The 3D Xray imaging result of the defects showed a good agreement with the defect anatomical morphologies. It was observed that the pore defect was accompanied by MC carbides, micro-crack, and non-metallic inclusions. The origin of pore defect was attributed to the shrinkage pores, inclusion and the complex precipitates. The analysis showed that the pore defects in GH4710 alloy was associated with strong micro-segregation and complex phase precipitation during solidification, induced by the high weight content of Ti and C in the alloy.

关键词： Ni-based superalloy Defects 3D X-ray imaging High Ti content

花岗质岩浆作用及后期演化过程:来自矿物原位微区成分与同位素组成的制约

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

岩石学报 2024年第3期40卷 785-810页

作者：龙欣雨唐杰许文良吉林大学地球科学学院长春130061 自然资源部东北亚矿产资源评价重点实验室长春130061

花岗岩作为大陆地壳的重要组成部分,其岩浆作用过程一直是地学领域研究的热点。传统上利用全岩地球化学和同位素数据来示踪花岗岩成因和演化过程的方法已不够准确,为此,本文系统总结了近年来报导的花岗岩中单矿物的原位微区成分——这... 详细信息

花岗岩作为大陆地壳的重要组成部分,其岩浆作用过程一直是地学领域研究的热点。传统上利用全岩地球化学和同位素数据来示踪花岗岩成因和演化过程的方法已不够准确,为此,本文系统总结了近年来报导的花岗岩中单矿物的原位微区成分——这些数据记录了全岩数据无法识别的单矿物颗粒内部和不同矿物颗粒之间元素和同位素组成的变异特征,明显提高了对花岗质岩浆作用及后期演化过程的认识。首先,矿物原位微区成分对花岗质岩浆的源区性质和混合过程具有指示意义。花岗岩中岩浆锆石Hf同位素组成的变异可能暗示其源区在深熔作用过程中发生了锆石的不平衡和选择性熔融,而未必是壳幔混合作用的结果,这是对“锆石效应”概念新的扩展;同一花岗岩样品中分选出的磷灰石颗粒可以具有完全不同的稀土元素配分模式、Eu异常、Sr含量和Sr-Nd同位素组成等,表明它们中的部分颗粒是岩浆形成和上升过程中从围岩捕获的,是小规模地壳混染作用的产物;榍石的微区成分分带记录了多种岩浆混合过程,也反映了熔体成分、氧逸度和温度等因素的变化;花岗岩与其中发育的包体、捕虏体和相关围岩的锆石Hf-O同位素和磷灰石Sr-Nd同位素组成可以记录上述岩石在形成过程中经历岩浆混合和同化混染等作用。其次,矿物原位微区成分可以反映花岗质岩浆的分离结晶过程。岩浆成因磷灰石不同的稀土元素配分模式可能指示它们受到了其他矿物分离结晶作用的影响,如帘石族、榍石、角闪石、斜长石等;花岗伟晶岩系统中岩浆成因独居石Sm/Nd值在不同岩带中的规律性变化揭示了岩浆分离结晶程度的差异;榍石的多种微区元素含量和它们之间的协变关系受控于花岗质岩浆的结晶分异过程和氧化还原状态;岩浆成因绿帘石族矿物的震荡环带表明在绿帘石结晶的晚期阶段花岗质岩浆中的Fe^(3+)含量降低,且结晶过程中褐帘石和绿帘石并不能形成完全连续的固溶体,因此晚期结晶的绿帘石环边与褐帘石核具有成分间断;根据角闪石的电子探针数据可以计算得到花岗质岩浆结晶时的温度、压力和f_(O2),并据此推断出岩浆起源的深度。此外,矿物原位微区成分可以记录花岗质岩石晚期经历的构造热事件和矿化作用过程。经历晚期变质/交代作用改造的花岗岩中的磷灰石具有低的轻稀土元素含量和变化很大的Nd同位素组成,导致花岗岩具有Nd-Hf位素体系解耦的特点;晚期变质/交代作用同样会改变磷灰石和榍石的δ^(18)O值,造成各副矿物之间δ^(18)O值相互解耦的现象;蚀变独居石的元素和U-Th-Pb同位素体系指示流体交代过程中多种置换反应的发生以及普通Pb混染和Pb丢失的过程;热液成因绿帘石族矿物的成分环带表明氧化环境下热液流体成分会不断演化,根据矿物-流体平衡模型,可以利用绿帘石成分计算出成矿作用发生的温度以及流体的pH值,研究表明绿帘石向流体中释放的大量Ca^(2+)有效促进了硫化物矿床的成矿作用进程。综上,单矿物原位微区成分分析技术的不断提高使我们对花岗质岩浆作用及后期演化过程的认识有了很大进步,在未来的研究中,如何取长补短,将这些数据进行良好地运用是本领域的重要方向。

关键词：花岗岩岩浆和岩浆期后过程矿物原位微区成分源区性质分离结晶过程变质和交代作用

Post-collisional mafic magmatism:Record of lithospheric mantle evolution in continental orogenic belt

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2020年第12期63卷 2029-2041页

作者： wenliang xu Zifu Zhao Liqun Dai College of Earth Sciences Jilin UniversityChangchun130061China CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei230026China Center for Excellence in Comparative Planetology Chinese Academy of Sciences(CAS)Hefei230026China

In order to better understand the role of post-collisional mafic magmatism at convergent plate boundaries in revealing the earth’s evolution,this paper has systematically summarized the research history of post-collisional mafic magmatism,different types of collision and their influence on the nature of orogenic mantle,the concept and implication of post-collisional magmatism,and the relationship between post-collisional mafic magmatism and orogenic mantle evolution and mineralization.Post-collisional mafic igneous rocks are not only the direct records for studying the nature and evolution of orogenic mantle,but also the important carriers for regional mineralization.However,the type and quantity of the crustal materials involved in modifying the overlying lithospheric mantle during collisional orogeny,the process and mechanism of such modification,and the major control factors and mechanism of mafic magmatism-related mineralization during the post-collisional period are the main contents and direction of future researches in this field.Therefore,the study of post-collisional mafic magmatism is of significant implications for developing the theory of plate tectonics.

关键词： Orogenic belt Types of collision Post-collisional mafic magmatism Orogenic mantle evolution Mineralization

Subduction history of the Paleo-Pacific slab beneath Eurasian continent: Mesozoic-Paleogene magmatic records in Northeast Asia

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2018年第5期61卷 527-559页

作者： Jie TANG wenliang xu Feng WANG Wenchun GE College of Earth Sciences Jilin University Key Laboratory of Mineral Resources Evaluation in Northeast Asia Ministry of Land and Resources of China

This paper presents a review on the rock associations, geochemistry, and spatial distribution of Mesozoic-Paleogene igneous rocks in Northeast Asia. The record of magmatism is used to evaluate the spatial-temporal extent and influence of multiple tectonic regimes during the Mesozoic, as well as the onset and history of Paleo-Pacific slab subduction beneath Eurasian continent. Mesozoic-Paleogene magmatism at the continental margin of Northeast Asia can be subdivided into nine stages that took place in the Early-Middle Triassic, Late Triassic, Early Jurassic, Middle Jurassic, Late Jurassic, early Early Cretaceous, late Early Cretaceous, Late Cretaceous, and Paleogene, respectively. The Triassic magmatism is mainly composed of adakitic rocks,bimodal rocks, alkaline igneous rocks, and A-type granites and rhyolites that formed in syn-collisional to post-collisional extensional settings related to the final closure of the Paleo-Asian Ocean. However, Triassic calc-alkaline igneous rocks in the Erguna-Xing'an massifs were associated with the southward subduction of the Mongol-Okhotsk oceanic slab. A passive continental margin setting existed in Northeast Asia during the Triassic. Early Jurassic calc-alkaline igneous rocks have a geochemical affinity to arc-like magmatism, whereas coeval intracontinental magmatism is composed of bimodal igneous rocks and A-type granites. Spatial variations in the potassium contents of Early Jurassic igneous rocks from the continental margin to intracontinental region, together with the presence of an Early Jurassic accretionary complex, reveal that the onset of the PaleoPacific slab subduction beneath Eurasian continent occurred in the Early Jurassic. Middle Jurassic to early Early Cretaceous magmatism did not take place at the continental margin of Northeast Asia. This observation, combined with the occurrence of low-altitude biological assemblages and the age population of detrital zircons in an Early Cretaceous accretionary complex,indicates that a strike-slip tectonic regime existed b

关键词：大陆平板亚洲东北历史早白垩纪晚三叠纪鄂霍次克海

Cotton GhMYB7 is predominantly expressed in developing fibers and regulates secondary cell wall biosynthesis in transgenic Arabidopsis

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2016年第2期59卷 194-205页

作者： Junfeng Huang Feng Chen Siyu Wu Juan Li wenliang xu Hubei Key Laboratory of Genetic Regulation and Integrative Biology School of Life Sciences Central China Normal University

The secondary cell wall in mature cotton fibers contains over 90%cellulose with low quantities of xylan and lignin.However,little is known regarding the regulation of secondary cell wall biosynthesis in cotton fibers.In this study,we characterized an R2R3-MYB transcription factor,Gh MYB7,in cotton.Gh MYB7 is expressed at a high level in developing fibers and encodes a MYB protein that is targeted to the cell nucleus and has transcriptional activation activity.Ectopic expression of Gh MYB7 in Arabidopsis resulted in small,curled,dark green leaves and also led to shorter inflorescence stems.A cross-sectional assay of basal stems revealed that cell wall thickness of vessels and interfascicular fibers was higher in transgenic lines overexpressing Gh MYB7 than in the wild type.Constitutive expression of Gh MYB7 in Arabidopsis activated the expression of a suite of secondary cell wall biosynthesis-related genes(including some secondary cell wall-associated transcription factors),leading to the ectopic deposition of cellulose and lignin.The ectopic deposition of secondary cell walls may have been initiated before the cessation of cell expansion.Moreover,Gh MYB7 was capable of binding to the promoter regions of At SND1 and At Ces A4,suggesting that Gh MYB7 may function upstream of NAC transcription factors.Collectively,these findings suggest that Gh MYB7 is a potential transcriptional activator,which may participate in regulating secondary cell wall biosynthesis of cotton fibers.

关键词：转基因拟南芥生物合成基因细胞壁次生壁调控棉花 MYB转录因子转录激活活性

Decoupling of Lu-Hf and Sm-Nd Isotopic System in Deep-Seated Xenoliths from the xuzhou-Suzhou Area,China: Differences in Element Mobility during Metamorphism

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2019年第6期30卷 1266-1279页

作者： Fanxue Meng wenliang xu Qinglin xu Jingliang Guo Yu Zhang Shandong Key Laboratory of Depositional Mineralization and Sedimentary Minerals Shandong University of Science and Technology^Qingdao 266590China Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and TechnologyQingdao 266061China College of Earth Sciences Jilin UniversityChangchun 130061China State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430074China

This paper presents whole-rock Hf isotopic data for a suite of eclogite and garnet clinopyroxenite xenoliths hosted in the Early Cretaceous dioritic intrusions from the xuzhou-Suzhou area along the southeastern margin of the Eastern Block of the North China Craton(NCC).Six of the eight studied xenolith samples plot significantly above the terrestrial Hf-Nd isotopic array and haveεHf(0)value up to+60.All the samples define a well correlated 147 Sm/144 Nd-143 Nd/144 Nd age of 2081 Ma,which is considered to record the granulite-facies metamorphism.In contrast,the Lu-Hf isotope system faithfully records the protolith information.The mineralogical assemblage,especially garnet and/or zircon(rutile to some extent)mainly controlled the decoupling of Hf-Nd isotope.The metamorphic modification on protolith characteristics and the differences in element mobility during metamorphism may also reinforce the observed decoupling between the Sm-Nd and Lu-Hf isotope systems;i.e.,the absence of the correlations inεNd-εHf and also 87 Sr/86 Sr-143 Nd/144 Nd diagram.The Lu/Hf isochron age of 2424 Ma is similar to the zircon age peak of the studied xenoliths and the dominant age of NCC basement,indicating that the igneous protolith has an affinity to the Archean basement of the NCC.Furthermore,the positiveεHf(t)values at 2500 Ma indicate a crustal growth event of 2500 Ma in the NCC.

关键词： lower-crust xenoliths Hf-Nd isotopes metamorphism modification crustal growth

Crustal Accretion and Reworking within the Khanka Massif： Evidence from Hf Isotopes of Zircons in Phanerozoic Granitoids

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2018年第2期29卷 255-264页

作者： Xiaoming Zhang wenliang xu Chenyang Sun Ting xu Feng Wang College of Earth Sciences Jilin University Changchun 130061 China State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan 430074 China

This paper presents a synthesis and analysis of geochronological, geochemical, and zircon Hf isotopic data of Phanerozoic granitoids within the Khanka massif, with the aim of revealing the ac- cretion and reworking processes of continental crust within the massif. Zircon U-Pb dating indicates that Phanerozoie granitic magmafism within the Khanka massif can be subdivided into eight stages： Late Cambrian, Middle-Late Ordovieian, Middle Silurian, Late Carboniferous, Early Permian, Middle--Late Permian to Early Triassic, Late Triassic-Early Jurassic, and Early Cretaceous. The zircon Hf isotopic compositions reveal that crustal accretionary events took place mainly in the Mesoprotero- zoie and Neoproterozoic. Through time, the zircon eHf（t） values gradually increase, indicating that the Phanerozoie granitic magmas were derived from the melting of progressively less ancient and more ju- venile crust. The zircon eHdt） values exhibit a gradual decrease with the increases in latitude, which im- plies that the amounts of ancient crustal components within the lower continental crust of the Khanka massif increased from south to north. At the same latitude range, the zircon Hf isotopic compositions also display some variations. We conclude, therefore, that significant horizontal and vertical heteroge- neities existed in the lower continental crust of the Khanka massif during the Phanerozoic.

关键词： Khanka massif Phanerozoic granitoid zircon Hf isotope crustal accretion and reworking.