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Search Results: 1 - 10 of 104306 matches for " Lifei Zhang "
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The40Ar /39 Ar metamorphic ages of Tangbale blueschists and their geological significance in West Junggar of Xinjiang
Lifei Zhang
Chinese Science Bulletin , 1997, DOI: 10.1007/BF02882787
Coesite in the eclogite and schist of the Atantayi Valley, southwestern Tianshan, China
Zeng Lü,LiFei Zhang
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-012-4979-4
Abstract: Coesite is an indicator mineral of ultra-high-pressure metamorphism. Since coesite was reported in the Habutengsu Valley, we have also found it in eclogite and schist from the Atantayi Valley in the southwestern Tianshan, China. Petrographic and micro-Raman analyses were carried out for the Atantayi metamorphic rocks and coesite was recognized in the predominant rock types, i.e. schist and eclogite, from three sections. The coesite-bearing schist consists mainly of garnet, Na-Ca amphibole, quartz, white mica and albite; the coesite-bearing eclogite is mainly composed of omphacite, garnet, glaucophane and zoisite. The coesite occurs as various mineral inclusions within porphyroblastic garnet. Findings of coesite in eclogite and associated schist indicate not only the regional in situ formation of the Atantayi ultra-high-pressure eclogite, but also the large areal extent of ultra-high-pressure metamorphism in southwestern Tianshan, extending up to 10 km north-south and 60–80 km east-west.
Phase Equlibrium of Grossular bearing Prehnite Pumpellyite Facies:An Example From Metabasites in Saertuohai Ophiolite of Xinjiang

Zhang Lifei,

岩石学报 , 1997,
Abstract: 利用矿物内部一致性热力学数据,建立了在CaO-Al2O3-MgO-SiO2-H2O体系中含钙铝榴石的葡萄石-绿纤石变质相平衡,确立了在葡萄石-绿纤石-钙铝榴石-绿帘石-绿泥石-石英组合中出现绿纤石-钙铝榴石共生、葡萄石-绿纤石共生、葡萄石-绿帘石共生和绿泥石-绿帘石-钙铝榴石共生的PT区间及其意义。根据该相平衡计算了新疆萨尔托海蛇绿岩中变基性岩石的葡萄石-绿纤石相变质PT条件为T=325℃~335℃,P=0.45~0.475GPa。并讨论了Fe3+=Al替代对于形成钙铝榴石-绿纤石共生的影响。本文的研究表明,葡萄石-绿纤石-钙铝榴石-绿帘石-绿泥石-石英共生组合是葡萄石-绿纤石相中偏高压组合,钙铝榴石-绿纤石共生与绿纤石-阳起石相一样代表着葡萄石-绿纤石相中较高压相,钙铝榴石在葡萄石-绿纤石相中是可以稳定存在的。
The Petrochemical Features of the Volcanic Rocks in Okinawa Trough and Their Geological Significance


岩石学报 , 1997,
Abstract: It has been found that volcanic rork in Okinawa Trough includes basalt, basaltic andesite, andesite, trachyandesite, trachydacite, dacite and rhyolite. The studies show that the rocks in Okinawa Trough is of a subalkaline rock series.The basic rocks belong to a transitional form between tholeiite series and calc alkalic series while most of the intermidiate rocks and acid rocks belong to calc alkalic series.They were formed since Policene and at different stages during the fractional crystallization of the initial basaltic magma which originated from the enriched mantle under the bottom.The consistency in the fractional crystallzation devoloping and the variance in the relationships among petrochemical indexes were resulted from the independent evolving stocks of the magma separated by the rift block, which was originally quick rising and non hybridized.
A Hybrid Algorithm to Address Ambiguities in Deformable Image Registration for Radiation Therapy  [PDF]
Song Gao, Yongbin Zhang, Jinzhong Yang, Catherine H. Wang, Lifei Zhang, Laurence E. Court, Lei Dong
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2012, DOI: 10.4236/ijmpcero.2012.12007
Abstract: We proposed the use of a hybrid deformable image registration approach that combines compact-support radial basis functions (CSRBF) spline registration with intensity-based image registration. The proposed method first uses the pre-viously developed image intensity-based method to achieve voxel-by-voxel correspondences over the entire image re-gion. Next, for those areas of inaccurate registration, a sparse set of landmark correspondences was defined for local deformable image registration using a multi-step CSRBF approach. This hybrid registration takes advantage of both intensity-based method for automatic processing of entire images and the CSRBF spline method for fine adjustment over specific regions. The goal of using this hybrid registration is to locally control the quality of registration results in specific regions of interest with minimal human intervention. The major applications of this approach in radiation ther-apy are for the corrections of registration failures caused by various imaging artifacts resulting in, low image contrast, and non-correspondence situations where an object may not be imaged in both target and source images. Both synthetic and real patient data have been used to evaluate this hybrid method. We used contours mapping to validate the accuracy of this method on real patient image. Our studies demonstrated that this hybrid method could improve overall registra-tion accuracy with moderate overhead. In addition, we have also shown that the multi-step CSRBF registration proved to be more effective in handling large deformations while maintaining the smoothness of the transformation than origi-nal CSRBF.
The40Ar/39Ar age record of formation and uplift of the blueschists and eclogites in the western Tianshan Mountains
Jun Gao,Lifei Zhang,Shengwei Liu
Chinese Science Bulletin , 2000, DOI: 10.1007/BF02884989
Abstract: The40Ar/39Ar ages indicate that the eclogite facies rocks of the Hasiate slice in the western Tianshan Mountains were formed at the early stage of Devonian (401 Ma) and had been uplifted to the greenschist facies tectonic level in the middle stage of Devonian (381 Ma). The formation and uplift of the blueschists of the Akesayi slice are constrained to the late stage of Devonian (370-364 Ma). The different tectonic slices in the high-pressure metamorphic belt have experienced the different uplift history.
Developing the plate tectonics from oceanic subduction to continental collision
YongFei Zheng,Kai Ye,LiFei Zhang
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0464-0
Abstract: The studies of continental deep subduction and ultrahigh-pressure metamorphism have not only promoted the development of solid earth science in China, but also provided an excellent opportunity to advance the plate tectonics theory. In view of the nature of subducted crust, two types of subduction and collision have been respectively recognized in nature. On one hand, the crustal subduction occurs due to underflow of either oceanic crust (Pacific type) or continental crust (Alpine type). On the other hand, the continental collision proceeds by arc-continent collision (Himalaya-Tibet type) or continent-continent collision (Dabie-Sulu type). The key issues in the future study of continental dynamics are the chemical changes and differential exhumation in continental deep subduction zones, and the temporal-spatial transition from oceanic subduction to continental subduction.
An Initilization Method for Subspace Clustering Algorithm
Qingshan Jiang,Yanping Zhang,Lifei Chen
International Journal of Intelligent Systems and Applications , 2011,
Abstract: Soft subspace clustering is an important part and research hotspot in clustering research. Clustering in high dimensional space is especially difficult due to the sparse distribution of the data and the curse of dimensionality. By analyzing limitations of the existing algorithms, the concept of subspace difference and an improved initialization method are proposed. Based on these, a new objective function is given by taking into account the compactness of the subspace clusters and subspace difference of the clusters. And a subspace clustering algorithm based on k-means is presented. Theoretical analysis and experimental results demonstrate that the proposed algorithm significantly improves the accuracy.
The geological characteristics of oceanic-type UHP metamorphic belts and their tectonic implications: Case studies from Southwest Tianshan and North Qaidam in NW China
LiFei Zhang,Zeng Lü,GuiBin Zhang,ShuGuang Song
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0386-2
Abstract: The geological characteristics of ultrahigh-pressure (UHP) metamorphic belts formed by deep subduction of oceanic crust are summarized in this paper. Oceanic-type UHP metamorphic belt is characterized by its protolithic assemblage of typical oceanic crust, the peak metamorphic temperature <600°, P-T path undergoing blueschist facies during prograde and retrograde metamorphic evolution, respectively, with low geothermal gradient of cold subduction. The further study of oceanic-type UHP metamorphic belt is very significant for constructing metamorphic reaction series of cold subduction zone, for understanding how aqueous fluids were transported into deep mantle and for classifying the types of UHP metamorphism in cold subduction zone. The uplift and exhumation mechanism of oceanic UHP metamorphic rocks is one of the most challenging problems in the study of UHP metamorphism, which is very important for understanding the geodynamic mechanism of solid Earth. As a traveler subducted into the mantle depth and then uplifted to the surface, oceanic-type UHP metamorphic belts witness the bulk process from the subduction to exhumation and is an ideal target to study the geochemical behavior and cycling of elements in subduction zones. The tectonic evolution of one convergent orogenic belt can be usually divided into two stages of oceanic subduction and followed continental subduction and collision, and the two best-established examples of orogenic belts are Alps and Himalaya. Therefore, the study of oceanic-type UHP metamorphic belt is the frontier of the current plate tectonic theory. As two case studies, the current status and existing problems of oceanic-type UHP metamorphic belts in Southwest Tianshan and North Qaidam, NW China, are reviewed in this paper.
Rho and Ras GTPases in semaphorin-mediated neuronal development  [PDF]
Lifei Fan, Morigen  
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.41A020

Neurons are highly polarized cells with a single long axon and multiple dendrites, all of which are actinrich structures. The precise regulation of neuronal cell morphology is a fundamental aspect of neurobiology. The major role of Rho GTPases, which is conserved in all eukaryotes, is to regulate the actin and microtubule cytoskeleton. Therefore theRhoGTPases are key regulators of neuronal morphology during development besides their canonical functions in actin cytoskeletal regulation, cell migration and cell cycle progression. Semaphorins are a family of secreted or transmembrane proteins, which function through their receptor plexins and/or neuropilins to act as the repulsive or attractive guidance cues for axons and dendrites. It has been demonstrated that the fully activetion of plexins appears to be dependent on the binding of RhoGTPases to theRhobinding domain (RBD) and Semaphorin to the extracellular region. Here, we summarize the functions of the small Rho GTPases in two well-studied vertebrate Semaphorins, Sema3Aand Sema4D; and the potential roles of the small Rho GTPases in some poorly-studied vertebrate Semaphorins Sema5A, Sema6Aand Sema7A. We also summarize the functions of different members of Ras family, R-Ras, M-Ras and Rap, in Semaphorin signalling pathways as well.

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