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Atomic-scale characterization of two-dimensional magnets and their heterostructures

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ChemPhysMater 2023年第4期2卷 282-294页

作者： Yuli Huang Mingyue Sun Yihe Wang andrew thye shen wee Wei Chen Joint School of National University of Singapore and Tianjin University International Joint Institute of Tianjin UniversityFuzhou 350207China Department of Physics National University of SingaporeSingapore 117551Singapore Department of Chemistry National University of SingaporeSingapore 117542Singapore

The realization of long-range magnetic ordering in two-dimensional(2D)van der Waals systems significantly expands the scope of the 2D family as well as their possible spin-related phenomena and device *** atomically thin nature of 2D materials makes their magnetically ordered states sensitive to local environments,and this necessitates advanced characterization at the atomic ***,we briefly review several representative 2D magnetic systems,namely,iron chalcogenides,chromium chalcogenides,chromium trihalides,and their *** powerful scanning-probe microscopy,atomically resolved characterization of their crystalline configurations,electronic structures,and magnetization distributions has been achieved,and novel phenomena such as giant tunneling magnetoresistance and topological superconductivity have been ***,we discuss the challenges and new perspectives in this flourishing field.

关键词： Two-dimensional magnets Two-dimensional heterostructures Scanning probe microscopy Spin-polarized configuration

Oxygen-induced controllable p-type doping in 2D semiconductor transition metal dichalcogenides

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Nano Research 2020年第12期13卷 3439-3444页

作者： Qijie Liang Jian Gou Arramel Qian Zhang Wenjing Zhang andrew thye shen wee SZU-NUS Collaborative Innovation Center for Optoelectronic Science&Technology International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of EducationCollege of Optoelectronic EngineeringShenzhen UniversityShenzhen518060China Department of Physics National University of Singapore2 Science Drive 3Singapore117551Singapore Department of Materials Science and Engineering National University of SingaporeSingapore117574Singapore Centre for Advanced 2D Materials National University of SingaporeBlock S146 Science Drive 2Singapore117546Singapore

Exposure to oxygen alters the physical and chemical properties of two-dimensional(2D)transition metal dichalcogenides(TMDs).In particular,oxygen in the ambient may influence the device stability of 2D TMDs over *** the doping of 2D TMDs,especially hole doping is highly desirable towards their device ***,controllable oxygen-induced p-type doping in a range of hexagonal(MoTe2,WSe2,MoSe2 and PtSe2)and pentagonal(PdSe2)2D TMDs are *** tunneling microscopy,electrical transport and X-ray photoelectron spectroscopy are used to probe the origin of oxygen-derived hole *** mechanisms are postulated that contribute to the hole doping in 2D TMDs,namely charge transfer from absorbed oxygen molecules,surface oxides,and chalcogen atom *** work provides insights into the doping effects of oxygen,enabling the engineering of 2D TMDs properties for nanoelectronic applications.

关键词： two-dimensional transition metal dichalcogenides oxygen induced doping oxygen substitution charge transfer

6H-SiC(0001)-63^(1/3)×63^(1/3)R30°重构表面的同步辐射角分辨光电子能谱研究

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物理学报 2009年第6期58卷 4288-4294页

作者：武煜宇陈石高新宇 andrew thye shen wee 徐彭寿中国科学技术大学国家同步辐射实验室合肥230029 新加坡国立大学物理系新加坡117542

利用同步辐射角分辨光电子能谱(SRARPES)对6H-SiC(0001)-63^(1/3)×63^(1/3)R30°重构表面的电子结构和表面态进行了研究.通过鉴别价带谱中来自于体态的信息,可以推断出重构表面的费米能级位于体态价带顶之上(2.1±0.1)eV处.实验测出的... 详细信息

利用同步辐射角分辨光电子能谱(SRARPES)对6H-SiC(0001)-63^(1/3)×63^(1/3)R30°重构表面的电子结构和表面态进行了研究.通过鉴别价带谱中来自于体态的信息,可以推断出重构表面的费米能级位于体态价带顶之上(2.1±0.1)eV处.实验测出的体能带结构与理论计算的结果较为符合.在重构表面上发现三个表面态,分别位于结合能-0.48eV(S0),-1.62eV(S1)和-4.93eV(S2)处.沿着表面布里渊区的高对称线ΓKM方向,测量了相关表面态的能带色散,只有表面态S0(-0.48eV)表现出了所希望的63×63R30°重构周期性.根据实验现象,可以认为,表面态S0应归结于重构表面的C—C悬键,而表面态S1则由重构表面未钝化的C悬键所导致.

关键词：角分辨光电子能谱碳化硅(SiC) 电子结构表面态

Structuring Nonlinear Wavefront Emitted from Monolayer Transition-Metal Dichalcogenides

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Research 2020年第1期2020卷 1721-1730页

作者： Xuanmiao Hong Guangwei Hu Wenchao Zhao Kai Wang Shang Sun Rui Zhu Jing Wu Weiwei Liu Kian Ping Loh andrew thye shen wee Bing Wang Andrea Alù Cheng-Wei Qiu Peixiang Lu Wuhan National Laboratory for Optoelectronics and School of Physics Huazhong University of Science and TechnologyWuhan 430074China Department of Electrical and Computer Engineering National University of Singapore4 Engineering Drive 3Singapore 117583 Advanced Science Research Center City University of New YorkNew York 10031USA Department of Physics National University of Singapore2 Science Drive 3Singapore 117542 Institute of Materials Research and Engineering Agency for ScienceTechnology and Research2 Fusionopolis WayInnovis#08-03Singapore 138634 Department of Chemistry National University of Singapore3 Science Drive 3Singapore 17543 Centre for Advanced 2D Materials National University of SingaporeBlock S146 Science Drive 2Singapore 117546 Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of TechnologyWuhan 430205China

The growing demand for tailored nonlinearity calls for a structure with unusual phase discontinuity that allows the realization of nonlinear optical chirality,holographic imaging,and nonlinear wavefront ***-metal dichalcogenide(TMDC)monolayers offer giant optical nonlinearity within a few-angstrom thickness,but limitations in optical absorption and domain size impose restriction on wavefront control of nonlinear emissions using classical light *** contrast,noble metal-based plasmonic nanosieves support giant field enhancements and precise nonlinear phase control,with hundred-nanometer pixellevel resolution;however,they suffer from intrinsically weak nonlinear ***,we report a multifunctional nonlinear interface by integrating TMDC monolayers with plasmonic nanosieves,yielding drastically different nonlinear functionalities that cannot be accessed by either *** a hybrid nonlinear interface allows second-harmonic(SH)orbital angular momentum(OAM)generation,beam steering,versatile polarization control,and holograms,with an effective SH nonlinearityχ^((2))of~25 nm/*** designer platform synergizes the TMDC monolayer and plasmonic nanosieves to empower tunable geometric phases and large field enhancement,paving the way toward multifunctional and ultracompact nonlinear optical devices.

关键词： nonlinearity Transition yielding

Two-dimensional ferromagnetic superlattices

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National Science Review 2020年第4期7卷 745-754页

作者： Shanshan Liu Ke Yang Wenqing Liu Enze Zhang Zihan Li Xiaoqian Zhang Zhiming Liao Wen Zhang Jiabao Sun Yunkun Yang Han Gao Ce Huang Linfeng Ai Ping Kwan Johnny Wong andrew thye shen wee Alpha T.N'Diaye Simon A.Morton Xufeng Kou Jin Zou Yongbing Xu Hua Wu Faxian Xiu State Key Laboratory of Surface Physics and Department of Physics Fudan University Institute for Nanoelectronic Devices and Quantum Computing Fudan University Laboratory for Computational Physical Sciences (MOE) Fudan University Department of Electronic Engineering Royal Holloway University of London School of Electronic Science and Engineering Nanjing University Materials Engineering The University of Queensland Department of Physics National University of Singapore Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore Lawrence Berkeley National Laboratory School of Information Science and Technology Shanghai Tech University Centre for Microscopy and Microanalysis The University of Queensland Collaborative Innovation Center of Advanced Microstructures

Mechanically exfoliated two-dimensional ferromagnetic materials(2 D FMs) possess long-range ferromagnetic order and topologically nontrivial skyrmions in few layers. However, because of the dimensionality effect, such few-layer systems usually exhibit much lower Curie temperature(TC) compared to their bulk counterparts. It is therefore of great interest to explore effective approaches to enhance their TC, particularly in wafer-scale for practical applications. Here, we report an interfacial proximity-induced high-TC2 D FM FeGe Te(FGT) via A-type antiferromagnetic material Cr Sb(CS) which strongly couples to FGT. A superlattice structure of(FGT/CS)n, where n stands for the period of FGT/CS heterostructure, has been successfully produced with sharp interfaces by molecular-beam epitaxy on 2-inch wafers. By performing elemental specific X-ray magnetic circular dichroism(XMCD) measurements, we have unequivocally discovered that TCof 4-layer FeGeTecan be significantly enhanced from 140 K to230 K because of the interfacial ferromagnetic coupling. Meanwhile, an inverse proximity effect occurs in the FGT/CS interface, driving the interfacial antiferromagnetic Cr Sb into a ferrimagnetic state as evidenced by double-switching behavior in hysteresis loops and the XMCD spectra. Density functional theory calculations show that the Fe-Te/Cr-Sb interface is strongly FM coupled and doping of the spin-polarized electrons by the interfacial Cr layer gives rise to the TCenhancement of the FeGeTefilms, in accordance with our XMCD measurements. Strikingly, by introducing rich Fe in a 4-layer FGT/CS superlattice, TCcan be further enhanced to near room temperature. Our results provide a feasible approach for enhancing the magnetic order of few-layer 2 D FMs in wafer-scale and render opportunities for realizing realistic ultra-thin spintronic devices.

关键词： 2D ferromagnetic material room temperature 2-inch Fe3GeTe2 film wafers proximity effect (Fe3GeTe2/CrSb)nsuperlattice

Effects of organic fertilizers produced using different techniques on rice grain yield and ammonia volatilization in double-cropping rice fields

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Pedosphere 2024年第1期34卷 110-120页

作者： Mingcheng HU andrew JWADE Weishou shen Zhenfang ZHONG Chongwen QIU Xiangui LIN Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment Technologyand School of Environmental Science and EngineeringNanjing University of Information Science and TechnologyNanjing 210044China Department of Geography and Environmental Science University of ReadingReading RG65DWUK Haina Research Institute of Guangdong Haina Agricultural Co. Ltd.Huizhou 516000China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China

Ammonia(NH_(3)) volatilization from rice fields contributes to poor air quality and indicates low nitrogen use efficiency. Although organic fertilizers can meet the nitrogen requirement for rice growth, the simultaneous effects of organic fertilizers on NH_(3) volatilization and rice yield in paddy fields are poorly understood and quantified. To address this gap in our knowledge, experimental field plots were established in a conventional double-cropping paddy field in the Pearl River Delta region, southern China. Five fertilizer treatments were used besides the control with no fertilizer: fresh organic fertilizer, successively composted organic fertilizer, chemically composted organic fertilizer, mixture of chemically composted organic fertilizer with inorganic fertilizer, and chemical fertilizer. Ammonia volatilization was measured using a batch-type airflow enclosure method. No significant differences in grain yield were observed among organic and chemical fertilizer treatments. However, compared with chemical fertilizer, chemically composted organic fertilizer and successively composted organic fertilizer significantly decreased total NH_(3) volatilization by 70% and 68%, respectively. The ammonium-nitrogen concentration in field surface water correlated strongly(P < 0.01) and positively with NH_(3) volatilization across fertilization treatments. Our findings demonstrate that chemically composted organic fertilizer can sustain rice yield while reducing NH_(3) volatilization. An important future step is to promote these field measurements to similar rice cultivation areas to quantify the regional-and national-scale impact on air quality and nitrogen deposition in sensitive areas, and to design and implement better fertilizer management practices.

关键词： air quality crop production manure NH_(3)emission nitrogen use efficiency

Effects of different organic fertilizers on nitrous oxide and methane emissions from double-cropping rice fields

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Pedosphere 2024年第1期34卷 52-62页

作者： Mingcheng HU andrew J.WADE Weishou shen Zhenfang ZHONG Chongwen QIU Xiangui LIN Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjing 210044China Department of Geography and Environmental Science University of ReadingReading RG66 DWUK Haina Research Institute of Guangdong Haina Agricultural Co. Ltd.Huizhou 516000China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China

Rice fields are a major source of greenhouse gases,such as nitrous oxide (N_(2)O) and methane (CH_(4)).Organic fertilizers may potentially replace inorganic fertilizers to meet the nitrogen requirement for rice growth;however,the simultaneous effects of organic fertilizers on N_(2)O and CH_(4)emissions and crop yield in paddy fields remain poorly understood and *** this study,experimental plots were established in conventional double-cropping paddy fields in the Pearl River Delta,China,including an unfertilized control and five fertilizer treatments with fresh organic fertilizer (FOF),successively composted organic fertilizer (SOF),chemically composted organic fertilizer (COF),COF supplemented with inorganic fertilizer (COIF),and chemical fertilizers (CFs)(TFOF,TSOF,TCOF,TCOIF,and TCF,respectively).Paddy field soils behaved simultaneously as an N_(2)O sink (cumulative N_(2)O emission:-196 to-381 g N ha^(-1)) and as a CH_(4)source (cumulative CH_(4)emission:719 to 2 178 kg ha^(-1)).Compared to CFs,the effects of organic fertilizers on N_(2)O emission were not *** contrast,total annual CH_(4)emission increased by 157%,132%,125%,and 37%in TFOF,TCOF,TSOF,and TCOIF,respectively,compared to *** TCOIF,rice yield was maintained,while CH_(4)emission was not significantly increased from the paddy fields characterized by a prolonged flood *** important next step is to extend these field-based measurements to larger rice cultivation areas to quantify the regional and national-scale impacts on greenhouse gas emissions and to help determine the optimum practice for fertilizer use.

关键词： crop production global warming potential greenhouse gases manure paddy sustainable agriculture

Geometric phase helical PSF for simultaneous orientation and 3D localization microscopy

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Chinese Optics Letters 2024年第3期22卷 25-30页

作者：周勇壮张洪硕沈咏 andrew R.Harvey 邹宏新 Institute for Quantum Science and Technology College of ScienceNational University of Defense TechnologyChangsha 410073China Hunan Key Laboratory of Mechanism and Technology of Quantum Information Changsha 410073China School of Physics and Astronomy University of GlasgowGlasgow G128QQUK

The 3D location and dipole orientation of light emitters provide essential information in many biological,chemical,and physical *** acquisition of both information types typically requires pupil engineering for 3D localization and dual-channel polarization splitting for orientation *** we report a geometric phase helical point spread function for simultaneously estimating the 3D position and dipole orientation of point *** has a compact and simpler optical configuration compared to polarization-splitting techniques and yields achromatic phase modulation in contrast to pupil engineering based on dynamic phase,showing great potential for single-molecule orientation and localization microscopy.

关键词： PSF engineering geometric phase single-molecule orientation and localization microscopy

RNA m^(6)A reader YTHDF2 facilitates precursor miR-126 maturation to promote acute myeloid leukemia progression

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Genes & Diseases 2024年第1期11卷 382-396页

作者： Zheng Zhang Keren Zhou Li Han andrew Small Jianhuang Xue Huilin Huang Hengyou Weng Rui Su Brandon Tan Chao shen Wei Li Zhicong Zhao Ying Qing Xi Qin Kitty Wang Keith Leung Mark Boldin Chun-Wei Chen David Ann Zhijian Qian Xiaolan Deng Jianjun Chen Zhenhua Chen Department of Systems Biology Beckman Research Institute of City of HopeMonroviaCA 91016USA Irell and Manella Graduate School of Biological Sciences Beckman Research Institute of City of HopeDuarteCA 91010USA Gehr Family Center for Leukemia Research City of HopeDuarteCA 91010USA Sun Yat-sen University Cancer Center State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineGuangzhouGuangdong 510060China Guangzhou Laboratory GuangzhouGuangdong 510005China Bioland Laboratory GuangzhouGuangdong 51005China Department of Liver Surgery Renji HospitalShanghai Jiao Tong University School of MedicineShanghai 200127China Department of Diabetes Complications and Metabolism Beckman Research Institute of City of HopeDuarteCA 91010USA Department of Biochemistry and Molecular Biology University of FloridaGainesvilleFL 32603USA Tongji Hospital Affiliated to Tongji University Frontier Science Center for Stem Cell ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghai 200092China School of Pharmacy China Medical UniversityShenyangLiaoning 110001China

As the most common internal modification of mRNA,Ne-methyladenosine(m^(6)A)and its regulators modulate gene expression and play critical roles in various biological and patholog-ical processes including *** was reported previously that m^(6)A methyltransferase(writer),methyltransferase-like 3(METTL3)adds m^(6)A in primary microRNAs(pri-miRNAs)and fa-cilitates its processing into precursor miRNAs(pre-miRNAs).However,it is unknown whether m^(6)A modification also plays a role in the maturation process of pre-miRNAs and(if so)whether such a function contributes to ***,we found that YTHDF2 is aberrantly overexpressed in acute myeloid leukemia(AML)patients,especially in relapsed patients,and plays an onco-genic role in ***,YTHDF2 promotes expression of miR-126-3p(also known as miR-126,as it is the main product of precursor miR-126(pre-miR-126)),a miRNA that was reported as an oncomiRNA in AML,through facilitating the processing of pre-miR-126 into mature ***,YTHDF2 recognizes m^(6)A modification in pre-miR-126 and recruits AGO2,a regulator of pre-miRNA processing,to promote the maturation of ***2 posi-tively and negatively correlates with miR-126 and miR-126's downstream target genes,respec-tively,in AML patients,and forced expression of miR-126 could largely rescue YTHDF2/Ythdf2 depletion-mediated suppression on AML cell growth/proliferation and leukemogenesis,indi-cating that miR-126 is a functionally important target of YTHDF2 in ***,our studies not only reveal a previously unappreciated YTHDF2/miR-126 axis in AML and highlight the ther-apeutic potential of targeting this axis for AML treatment,but also suggest that m^(6)A plays a role in pre-miRNA processing that contributes to tumorigenesis.

关键词： AML miR-126 N^(6)-methyladenosine Pre-miRNA maturation YTHDF2