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Frontiers of physics 2012年第2期7卷 175-192页

作者： yulin chen (1) (2) (3) 1. Department of Physics University of Oxford Clarendon Laboratory Parks Road Oxford OX1 3PU UK2. Stanford Institute for Materials and Energy Sciences SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park CA 94025 USA3. Geballe Laboratory for Advanced Materials Departments of Physics and Applied Physics Stanford University Stanford CA 94305 USA

Three-dimensional （3D） topological insulators represent a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. The unusual surface states of topological insulators rise from the nontrivial topology of their electronic structures as a result of strong spin-orbital coupling. In this review, we will briefly introduce the concept of topological insu- lators and the experimental method that can directly probe their unique electronic structure： angle resolved photoemission spectroscopy （ARPES）. A few examples are then presented to demonstrate the unique band structures of different families of topological insulators and the unusual properties of the topological surface states. Finally, we will briefly discuss the future development of topological quantum materials.

关键词： topological insulator (TI) photoemission ARPES

Experimental and Numerical Study of Heat Transfer Characteristicsof Supercritical CO_(2) in Rectangular Channel PCHE

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Journal of Thermal Science 2024年第6期33卷 2299-2317页

作者： chen yulin WU Xinwen SHAO Yingjuan ZHONG Wenqi Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China

Channel structure has a significant effect on the heat transfer performance of *** this study,a set of rectangular straight channel PCHEs with different cross-section aspect ratios had been tested on S-CO_(2) heat transfer experimental platform,the effect of mass flow rate in both cold and heat sides,as well as the cross-section aspect ratio of the rectangular straight channel,on the heat transfer performance of PCHE was *** results show that the comprehensive heat transfer performance of the rectangular cross-section is better than that of the semicircular cross-section;increasing the aspect ratio can improve the comprehensive heat transfer performance of PCHE,but the strengthening effect diminishes as the aspect ratio *** the mass flow rate on both sides not only enhances the pre-cooler's cooling capacity and heat transfer,but also raises the pressure *** addition,an improved heat transfer correlation for rectangular cross-section PCHE was proposed,considering the effects of cross-sectional aspect ratio and pseudo-critical temperature is proposed in the range of Re from 3169 to 48474 and Pr from 0.98 to 12.5,the fited results better predict the local Nu and f magnitudes and trends in the pre-cooler under different cooling conditions,outperforming the simulated data and Gnielinski and Blasius correlation.

关键词： S-CO_(2) rectangular PCHE pre-cooler performance analysis local flow heat transfer characteris

ARPES investigation of the electronic structure and its evolution in magnetic topological insulator MnBi2+2nTe4+3n family

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National Science Review 2024年第2期11卷 81-93页

作者： Runzhe Xu Lixuan Xu Zhongkai Liu Lexian Yang yulin chen State Key Laboratory of Low Dimensional Quantum Physics Department of PhysicsTsinghua University School of Physical Science and Technology Shanghai Tech University and CAS-Shanghai Science Research Center Shanghai Tech Laboratory for Topological Physics Frontier Science Center for Quantum Information Collaborative Innovation Center of Quantum Matter Department of Physics Clarendon LaboratoryUniversity of Oxford

In the past 5 years,there has been significant research interest in the intrinsic magnetic topological insulator family compounds MnBi2+2nTe4+3n（where n=0,1,2…）.In particular,exfoliated thin films of MnBi2Te4have led to numerous experimental breakthroughs,such as the quantum anomalous Hall effect,axion insulator phase and high-Chern number quantum Hall effect without Landau ***,despite extensive efforts,the energy gap of the topological surface states due to exchange magnetic coupling,which is a key feature of the characteristic band structure of the system,remains experimentally *** electronic structure measured by using angle-resolved photoemission （ARPES） shows significant deviation from ab initio prediction and scanning tunneling spectroscopy measurements,making it challenging to understand the transport results based on the electronic *** paper reviews the measurements of the band structure of MnBi2+2nTe4+3nmagnetic topological insulators using ARPES,focusing on the evolution of their electronic structures with temperature,surface and bulk doping and film *** aim of the review is to construct a unified picture of the electronic structure of MnBi2+2nTe4+3ncompounds and explore possible control of their topological properties.

关键词： magnetic topological insulator MnBi2Te4 electronic structure angle-resolved photoemission spectroscopy

Gadd45a deletion aggravates hematopoietic stem cell dysfunction in ATM-deficient mice

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Protein & Cell 2014年第1期5卷 80-89页

作者： yulin chen Runan Yang Peng Guo Zhenyu Ju Institute of Aging Research School of Medicine Hangzhou Normal University Hangzhou 311121 China

Ataxia telangiectasia mutated （ATM） kinase plays an essential role in the maintenance of genomic stability. ATM-deficient （ATM-/-） mice exhibit hematopoietic stem cell （HSC） dysfunction and a high incidence of lym- phoma. Gadd45a controls cell cycle arrest, apoptosis and DNA repair, and is involved in the ATM-p53 mediated DNA damage response. However, the role of Gadd45a in regulating the functionality of ATM-/- HSCs is unknown. Here we report that Gadd45a deletion did not rescue the defects of T-cells and B-cells development in ATM-/- mice. Instead, ATM and Gadd45a double knockout （ATM-/- Gadd45a-/-） HSCs exhibited an aggravated defect in long-term self-renewal capacity compared to ATM-/- HSCs in HSC transplantation experiments. Fur- ther experiments revealed that the aggravated defect of ATM-/- Gadd45a-/- HSCs was due to a reduction of cell proliferation, associated with an accumulation of DNA damage and subsequent activation of DNA damage response including an up-regulation of p53-p21 signal- ing pathway. Additionally, ATM-/- Gadd45a-/- mice showed an increased incidence of hematopoietic malignancies, as well as an increased rate of metastasis than ATM-/- mice. In conclusion, Gadd45a deletion aggravated the DNA damage accumulation, which sub- sequently resulted in a further impaired self-renewal capacity and an increased malignant transformation in ATM-/- HSCs.

关键词： Gadd45a ATM hematopoietic stem cellsDNA damage

Deformation induced Elinvar behavior in Fe-Ni Invar alloy

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Science Bulletin 2018年第16期63卷 1040-1042页

作者： Fangyu Qin Fengshuang Lu yulin chen Jianmin Yang Xinqing Zhao School of Materials Science and Engineering Beihang University Beijing 100191 China Functional Materials Research Institute. Central Iron and Steel Research Institute Beijing 100081. China

Fe-Ni alloys exhibiting temperature-independent elastic modulus(Elinvar)and thermal expansion(Invar)properties have found wide and significant applications,such as liquefied natural gas tanks,micrometers,reed relays,hairsprings,etc.[1].Owing to the technical and theoretical importance of Invar and Elinvar effects,the underlying mechanisms of such effects have been

关键词：钢合金行为液化天然气材料科学影响因素继电器试验性磁性

Seismic attenuation in the lower mantle beneath Northeast China constrained from short-period reflected core phases at short epicentral distances

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Earth and Planetary Physics 2019年第6期3卷 537-546页

作者： BaoLong Zhang SiDao Ni yulin chen State Key Laboratory of Geodesy and Earth’s Dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences

The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle *** intrinsic attenuation in the lower mantle is highly sensitive to temperature,determining of the attenuation of the lower mantle could help us determine its thermal *** attempted to constrain the attenuation of the lower mantle by measuring the amplitude ratios of p to ScP on the vertical component and s to ScS on the tangential component at short epicentral distances for seismic wave data from deep earthquakes in Northeast *** calculated the theoretical amplitude ratios of p to ScP and s to ScS by using ray theory and the axial-symmetric spectral element method AxiSEM,as well as by considering the effects of radiation patterns,geometrical spreading,and ScP reflection *** comparing the observed amplitude ratios with the synthetic results,we constrained the quality factors as Qα≈3,000 and Qβ≈1,300 in the lower mantle beneath Northeast China,which are much larger than those in the preliminary reference Earth model(PREM)model of Qα~800 and Qβ~*** propose that the lower mantle beneath Northeast China is relatively colder than the average mantle,resulting in weaker intrinsic attenuation and higher *** estimated the temperature of the lower mantle beneath Northeast China as approximately 300–700 K colder than the global average value.

关键词： seismic attenuation lower mantle Northeast China reflected core phases thermal state

Phase Transformation in Al/Zn Multilayers during Mechanical Alloying

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Acta Metallurgica Sinica(English Letters) 2023年第10期36卷 1709-1718页

作者： chen chen Junjie Yu Jingyu Lu Jian Zhang Xuan Su chen-Hao Qian yulin chen Weixi Ji Manping Liu Department of Mechanical Engineering Jiangnan UniversityWuxi214122China Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology Jiangnan UniversityWuxi214122China School of Materials Science and Engineering Jiangsu UniversityZhenjiang212013China

In this work,mechanical alloying of the alternating stacked pure Al and Zn thin foils was accomplished via high-pressure torsion(HPT).In the alloyed Al-Zn system,an exotic phase transformation from hexagonal close-packed(HCP)to face-centered cubic(FCC)was *** atomic-scale evolution process and underlying mechanism of phase transformation down to atomic scale are provided by molecular dynamics simulation and high-resolution transmission electron *** HCP→FCC phase transformation was attributed to the sliding of Shockley partial dislocations generated at the Al-Zn grain boundaries,which resulted in an[2110][011]and(0001)/(111)orientation relationship between the two *** work provides a new approach for the in-depth study of the solid phase transformation of Al-Zn alloys and also shed lights on understanding the mechanical properties of the HPT processed Al-Zn alloys.

关键词： High-pressure torsion Phase transformation Al/Zn multilayers Mechanical alloying

Twin structure of the lath martensite in low carbon steel

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Progress in Natural Science:Materials International 2016年第2期26卷 169-172页

作者： Pan Zhang yulin chen Wenlong Xiao Dehai Ping Xinqing Zhao School of Materials Science and Engineering Beihang University School of Materials Science and Engineering Dalian Jiaotong University

It has been well accepted that the martensites in quenched carbon steels exhibit two typical morphologies which are closely dependent on the carbon content, i.e. lath martensite in low carbon steels and lenticular martensite in high carbon steels. Based on conventional belief, the lath martensites in low carbon steels are with high density dislocations as the substructure, in contrast to twin substructure in lenticular high carbon martensite. In the present work, an intensive transmission electron microscopy investigation was made to characterize the microstructures of the lath martensite in a low carbon steel of 0.2 wt%C. It was found that lots of lath martensites consist of twin as their substructure, rather than high density dislocations. In addition, nanoscale precipitates cohering with ferrite matrix were found at the twin interfaces. The orientation relationships between the precipitates and the ferrite matrix are in good agreement with that of primitive hexagonal ω phase in titanium alloys and other bcc metals or alloys.

关键词： Martensite Twin Lath Low carbon steel Martensitic transformation

Microstructure of ultrahigh carbon martensite

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Progress in Natural Science:Materials International 2018年第6期28卷 749-753页

作者： Chao Wang yulin chen Jingyun Han Dehai Ping Xinqing Zhao School of Materials Science and Engineering Beihang University School of Materials Science and Engineering Dalian Jiaotong University

Recent experimental investigations suggest that the martensite formed by quenching carbon steels(0.2–1.26 mass %C) are composed of twins and nanoscale ω particles in twin boundaries, rather than carbon supersaturated uniform solutions. In order to probe the microstructure of the martensite with ultrahigh carbon content, a novel strategy is employed in the present study to obtain ultrahigh carbon martensite(approximate2.1 mass %C) by quenching ductile cast iron. The microstructure of the martensite was intensively characterized by high resolution transmitting electron microscopy. It is indicated that the microstructure of the ultrahigh carbon martensites is composed of ultrafine {112} -type twins and high-density nano-scaled ω particles embedded in twin boundaries. These ω nanoparticles in twin boundaries could remarkably impede the deformation of the movement of the nanotwins in martensites, leading to poor ductility and strength of the quenched ductile cast iron. These findings not only reveal the substructures of ultrahigh carbon martensite, but also enhance the understanding of the mechanical behavior of high carbon steels and ductile cast irons.

关键词： Ultrahigh carbon martensite Ductile cast iron Nanotwin ω phase

Cathode infiltration with enhanced catalytic activity and durability for intermediate-temperature solid oxide fuel cells

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Chinese Chemical Letters 2022年第2期33卷 674-682页

作者： Yinghua Niu Weirong Huo Yuandong Yu Wenjun Li yulin chen Weiqiang Lv Yangtze Delta Region Institute(Huzhou)&School of Physics&School of Materials and Energy University of Electronic Science and Technology of ChinaHuzhou 313001China School of Materials Science and Engineering Tianjin University of TechnologyTianjin 300384China

To lower the operation temperature and increase the durability of solid oxide fuel cells(SOFCs), increasing attentions have been paid on developing cathode materials with good oxygen reduction reaction(ORR)activity at intermediate-temperature(IT, 500-750 ℃) range. However, most cathode materials exhibit poor catalytic activity, or they thermally mismatch with SOFC electrolytes and undergo severe degeneration. Infiltrating catalysts on existing backbone materials has been proved to be an efficient method to construct highly active and durable cathodes. In this mini-review, the advantages of infiltration-based cathode compared with new material-based cathodes are summarized. The merits and drawbacks of different backbones are illustrated. Different types of catalysts for infiltration are depicted in detail. Suggestions on the material/structure optimization of the infiltrated cathodes of IT-SOFC are provided.

关键词： Infiltration Cathode Solid oxide fuel cell Oxygen oxidation reaction Durability