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Classification of high-ordered topological nodes towards Moiré flat bands in twisted bilayers

Science China(Physics,Mechanics & Astronomy) 2024年第9期Mechanics & Astronomy) .卷 137-151页

作者： Fan Cui Congcong Le Qiang Zhang Xianxin Wu Jiangping Hu ching-kai chiu Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences RIKEN Interdisciplinary Theoretical and Mathematical Sciences(iTHEMS) CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of Sciences Kavli Institute of Theoretical Sciences University of Chinese Academy of Sciences New Cornerstone Science Laboratory

At magic twisted angles, Dirac cones in twisted bilayer graphene(TBG) can evolve into flat bands, serving as a critical playground for the study of strongly correlated physics. When chiral symmetry is introduced, rigorous mathematical proof confirms that the flat bands are locked at zero energy in the entire Moiré Brillouin zone(BZ). Yet, TBG is not the sole platform that exhibits this absolute band flatness. Central to this flatness phenomenon are topological nodes and their specific locations in the BZ. In this study, considering twisted bilayer systems that preserve chiral symmetry, we classify various ordered topological nodes in base layers and all possible node locations across different BZs. Specifically, we constrain the node locations to rotational centers,such as Γ and M points, to ensure the interlayer coupling retains equal strength in all directions. Using this classification as a foundation, we systematically identify the conditions under which Moiré flat bands emerge. Additionally, through the extension of holomorphic functions, we provide proof that flat bands are locked at zero energy, shedding light on the origin of the band flatness. Remarkably, beyond Dirac cones, numerous twisted bilayer nodal platforms can host flat bands with a degeneracy number of more than two, such as four-fold, six-fold, and eight-fold. This multiplicity of degeneracy in flat bands might unveil more complex and enriched correlation physics.

关键词： twisted bilayer systems high-ordered topological nodes Morié flat bands high degeneracy

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Review of Computational Approaches to Optimization Problems in Inhomogeneous Rods and Plates

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Communications on Applied Mathematics and Computation 2024年第1期6卷 236-256页

作者： Weitao Chen chiu-Yen Kao Department of Mathematics University of California at Riverside900 University AveRiversideCA92521USA Department of Mathematical Sciences Claremont McKenna College850 Columbia AveClaremontCA91711USA

In this paper,we review computational approaches to optimization problems of inhomogeneous rods and *** consider both the optimization of eigenvalues and the localization of *** problems are motivated by physical problems including the determination of the extremum of the fundamental vibration frequency and the localization of the vibration *** demonstrate how an iterative rearrangement approach and a gradient descent approach with projection can successfully solve these optimization problems under different boundary conditions with different densities given.

关键词： Inhomogeneous rods and plates Bi-Laplacian Optimization of eigenvalues Localization of eigenfunctions Rearrangement

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A prospective cohort of men with localized prostate cancer on active surveillance protocol in Hong Kong,China:what did we learn?

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Asian Journal of Andrology 2024年第3期26卷 245-249页

作者： Xiaobo Wu Ivan ching-Ho Ko Cindy Yeuk-Lam Hong Samuel Chi-Hang Yee Jeremy Yuen-Chun Teoh Samson Yun-Sang Chan Ho-Man Tam Chi-Kwok Chan Chi-Fai Ng Peter Ka-Fung chiu SH Ho Urology Centre Department of SurgeryFaculty of MedicineThe Chinese University of Hong KongHong KongChina

This study aimed to report the outcomes of active surveillance(AS)in the management of low-risk prostate cancer(PCa).It recruited87 men who were prospectively followed up according to the Prostate Cancer Research International Active Surveillance(PRIAS)protocol with local adaptation at SH Ho Urology Centre,Prince of Wales Hospital,Hong Kong,*** investigated the predictorsof disease progression and found that baseline prostate-specific antigen density(PSAD)and the presence of the highest ProstateImaging-Reporting and Data System(PI-RADS)score 5 lesion on magnetic resonance imaging(MRI)are significantly correlatedwith disease ***,men with PSAD>0.2 ng ml^(−2)or PI-RADS 4 or 5 lesions had significantly worse upgradingfree survival compared to those with PSAD≤0.2 ng ml−2 and PI-RADS 2 or 3 *** study concludes that AS is a safe andeffective management strategy for selected patients to defer radical treatment and that most disease progression can be detectedafter the first repeated *** combination of PSAD>0.2 ng ml^(−2)and PI-RADS 4 or 5 lesions may serve as a useful predictorof early disease progression and provide a guide to optimize follow-up protocols for men in different risk groups.

关键词： active surveillance cohort localized prostate cancer

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“If Somebody Needed Help, I Went Over”: Social Capital and Therapeutic Communities of Older Adult Farmers in British Columbia Floods

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International Journal of Disaster Risk Science 2024年第2期15卷 290-301页

作者： Kyle Breen Siyu Ru Luna Vandeweghe Jenna chiu Lindsay Heyland Haorui Wu School of Social Work Dalhousie UniversityHalifaxNS B3H 1S2Canada

Older adults in disaster contexts are often thought of as a passive, vulnerable population that lacks agency and capacities to cope in the aftermath. However, it can be argued that older adults may have underrecognized strengths that can be utilized pre-, peri-, and post-disaster. One of these strengths is older adults' unique social capital that stems from long-standing connections with other members of their respective communities. Using data from in-depth, semistructured interviews with farmers in British Columbia 3–11 months after the 2021 floods, this research explored the experiences of older adult farmers' recovery. The farmers discussed how they leveraged their social capital to aid in their recovery efforts from the flood event. By using their bonding social capital, older adult farmers transformed their existing, deep-rooted connections into post-disaster assistance. This, in turn, generated the idea of the therapeutic community, helping community members cope in the aftermath. This research indicated the need to further examine how older adults in disaster settings can be viewed as assets with community knowledge and skills as opposed to solely as a vulnerable population.

关键词： British Columbia Flood disaster Older adults Qualitative research Social capital Therapeutic community

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Detecting fake reviewers in heterogeneous networks of buyers and sellers:a collaborative training-based spammer group algorithm

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Cybersecurity 2024年第2期7卷 44-67页

作者： Qi Zhang Zhixiang Liang Shujuan Ji Benyong Xing Dickson K.W.chiu Shandong Provincial Key Laboratory of Wisdom Mine Information Technology Shandong University of Science and TechnologyQingdao 266590ShandongChina Zhejang University-University of linois at Urbana-Champaign Institute Haining 314499ZhejiangChina School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China Faculty of Education The University of Hong KongPok Fu LamHong KongChina

It is not uncommon for malicious sellers to collude with fake reviewers(also called spammers)to write fake reviews for multiple products to either demote competitors or promote their products'reputations,forming a gray industry *** detect spammer groups in a heterogeneous network with rich semantic information from both buyers and sellers,researchers have conducted extensive research using Frequent Item Mining-based and graph-based ***,these methods cannot detect spammer groups with cross-product attacks and do not jointly consider structural and attribute features,and structure-attribute correlation,resulting in poorer detection ***-fore,we propose a collaborative training-based spammer group detection algorithm by constructing a heterogene-ous induced sub-network based on the target product set to detect cross-product attack spammer *** jointly consider all available features,we use the collaborative training method to learn the feature representations of *** addition,we use the DBSCAN clustering method to generate candidate groups,exclude innocent ones,and rank them to obtain spammer *** experimental results on real-world datasets indicate that the overall detection performance of the proposed method is better than that of the baseline methods.

关键词： Spammer group Heterogeneous network Collaborative training DBSCAN

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Introduction of rare-earth element Sc in alloy design to modify wear features of dual-phase high-entropy alloy

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Rare Metals 2024年第2期43卷 817-828页

作者： Hao Ren Rui-Run Chen Xue-Feng Gao Tong Liu Gang Qin Yu-Lung chiu Shi-Ping Wu Jing-Jie Guo Guo National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin150001China School of Metallurgy and Materials University of BirminghamBirminghamB152TTUK

Tailoring the alloy composition,which induces the hard secondary phase to increase hardness and strength to improve the wear features,is a feasible approach for developing wear-resistant metal ***,a group of(AlCoCrFeNi)_(100–x)Sc_(x)(x=0–2.0,at%)high-entropy alloys(HEAs)are designed and the phase compositions and wear behaviors are ***-doped HEA series contain the primary body-centered cubic(BCC)and eutectic phases,in which the eutectic phase is composed of the alternately grown BCC and Laves *** addition promotes the diffusion of Ni atoms from BCC phase to form the Sc-rich Laves phase at the grain *** hardness increases due to solid solution strengthening and second phase *** the second phase strengthening plays a more significant role relative to solid solution *** phase and the oxides caused by wear heating prevent the direct contact between friction pair and HEAs,thus inducing a decreased wear rate from 6.82×10^(−5) to 3.47×10^(−5)m^(3)·N^(−1)·m^(−1).Moreover,the wear mechanism changes from adhesive wear,abrasive wear and oxidative wear to abrasive wear and oxidative wear.

关键词： High entropy alloy(HEA) Laves phase Hardness Wear mechanism

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A Hf-doped dual-phase high-entropy alloy: phase evolution and wear features

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Rare Metals 2024年第1期43卷 324-333页

作者： Hao Ren Rui-Run Chen Xue-Feng Gao Tong Liu Gang Qin Yu-Lung chiu Shi-Ping Wu Jing-Jie Guo National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China School of Metallurgy and Materials University of BirminghamEdgbastonBirmingham B152TTUK

Initially defined high entropy alloys(HEAs)usually exhibit a single-phase solid-solution ***,two and/or more types of phases in HE As possibly induce the desired microstructure features,which contribute to improving the wear properties of HE ***,we prepare a series of(AlCoCrFeNi)_(100-x)Hf_(x)(x=0,2,4and 6;at%) HEAs and concern their phase compositions,micro structures and wear *** leads to the formation of(Ni,Co)_(2)Hf-type Laves phase and tailors the microstructure from a body-centered cubic(BCC) singlephase structure to a hypoeutectic *** increased hardness from~HV 512.3 to~HV 734.1 is due to solid-solution strengthening,grain refinement strengthening and precipitated phase *** a few oxides(Al_(2)O_(3)+Cr_(2)O_(3)) caused by the wear heating contribute to an 85.5% decrease in wear rate of the HEA system from6.71×10^(-5) to 0.97×10^(-5) m^(3)·N^(-1)·m^(-1).In addition,Hf addition changes the wear mechanism from abrasive wear,mild oxidative wear and adhesive wear to oxidative wear and adhesive wear.

关键词： High entropy alloy Laves phase Hardness Wear mechanism

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Can You Help Me,Please?

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空中英语教室（初级版．大家说英语） 2024年第9期 35-38,54,55,56页

作者： Maria chiu 不详

Everyone needs help *** can ask,"Can you give me a hand?"Maybe you have to finish a *** need *** can ask,"Can you hand those scissors to me?"Or perhaps you need some advice or want someone's *** you have to solve a **... 详细信息

关键词： something someone You

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Make a BOOKMARK

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空中英语教室（初级版．大家说英语） 2024年第7期 32-33,54页

作者： Maria chiu 不详

句中cardstock“卡纸”和paper“纸”都是不可数名词,所以用法如下:1.前面不可以加不定冠词a;colorful paper.2.I need paper for my printer.我的打印机需要纸。

关键词： printer 不可数名词打印机

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The role ofγ-C2H5NO2 as a new transient liquid phase in cold sintering process of BaTiO3 composites

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Journal of Advanced Ceramics 2024年第7期13卷 942-955页

作者： Jitrawan Noisak Pimchanok Ieamviteevanich Thitirat Charoonsuk Phakkhananan Pakawanit Nattapong Pinpru Wanwilai Vittayakorn Tosapol Maluangnont Panpailin Seeharaj Theerachai Bongkarn Te-Wei chiu Naratip Vittayakorn Advanced Materials Research Unit School of ScienceKing Mongkut’s Institute of Technology LadkrabangBangkok 10520Thailand Department of Chemistry School of ScienceKing Mongkut’s Institute of Technology LadkrabangBangkok 10520Thailand Department of Materials Science Faculty of ScienceSrinakharinwirot UniversityBangkok 10110Thailand Synchrotron Research and Applications Division Synchrotron Light Research InstituteNakhon Ratchasima 30000Thailand Sustainability Centre Plastics Market Intelligent DepartmentPlastics Institute of ThailandBangkok 10110Thailand Electroceramics Research Laboratory College of Materials Innovation and TechnologyKing Mongkut's Institute of Technology LadkrabangBangkok 10520Thailand Department of Physics Faculty of ScienceNaresuan UniversityPhitsanulok 65000Thailand Research Center for Academic Excellence in Applied Physics Faculty of ScienceNaresuan UniversityPhitsanulok 65000Thailand Department of Materials and Mineral Resources Engineering "National"Taipei University of TechnologyTaipei 106TaiwanChina

Dielectric materials,such as barium titanate(BT)-based materials,have excellent dielectric properties but require high temperatures(above 1300℃)for ceramic fabrication,leading to high costs and energy *** cold sintering process(CSP)offers a solution to these issues and is gaining worldwide attention as an innovative fabrication *** this work,we proposed an alternative organic ferroelectric phase,gamma-glycine(γ-GC),which acts as a transient liquid phase to fabricate high-density composites with barium titanate(BT)at low temperatures through *** findings show that the density of 15γ-GC/85BT reached 96.7%±1.6%when it was sintered at 120℃for 6 h under 10 MPa uniaxial *** electron microscopy‒energy dispersive X-ray spectroscopy(SEM‒EDS)mappings of the composite suggested thatγ-GC completely underwent the precipitation-dissolution process and,therefore,filled between BT ***,X-ray diffraction(XRD)and Fourier-transform infrared spectroscopy(FTIR)confirmed the preservation ofγ-GC without undesired phase *** addition,the ferroelectric and dielectric properties ofγ-GC/BT composites have been *** high dielectric constant(εr)was 3600,and the low dielectric loss(tanδ)was 1.20 at 200℃and 100 kHz for the 15γ-GC/85BT *** hysteresis loop showed a remanent polarization(Pr)of 0.55µC·cm^(−2)and a coercive field(Ec)of 7.25 kV·cm^(−1).Our findings reaffirmed that an organic ferroelectric material(γ-GC)can act as a transient liquid phase in a CSP that can successfully and sustainably fabricateγ-GC/BT composites at low temperatures while delivering outstandingly high performance.

关键词： gamma-glycine(γ-GC) barium titanate(BT) cold sintering process organic ferroelectric materials dielectric properties ferroelectric properties

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