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On the half-quantized Hall conductance of massive surface electrons in magnetic topological insulator films

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Science china(Physics,Mechanics & Astronomy) 2024年第6期67卷 127-136页

作者： Rui chen shun-Qing Shen Department of Physics The University of Hong KongHong Kong 999077China Department of Physics Hubei UniversityWuhan 430062China

In topological insulators,massive surface states resulting from local symmetry breaking were thought to exhibit a half-quantized Hall conductance,obtained from the low-energy effective model in an infinite Brillouin *** a lattice model,the surface band is composed of a combination of surface states and bulk *** massive surface states alone may not be enough to support an exact one-half quantized surface Hall conductance in a finite Brillouin zone and the whole surface band always gives an integer quantized Hall conductance as enforced by the TKNN *** explore this,we investigate the band structures of a lattice model describing the magnetic topological insulator film that supports the axion insulator,chern insulator,and semi-magnetic topological insulator *** reveal that the gapped and gapless surface bands in the three phases are characterized by an integer-quantized Hall conductance and a half-quantized Hall conductance,*** propose an effective model to describe the three phases and show that the low-energy dispersion of the surface bands inherits from the surface Dirac *** gapped surface band manifests a nearly half-quantized Hall conductance at low energy near the center of Brillouin zone,but is compensated by another nearly half-quantized Hall conductance at high energy near the boundary of Brillouin zone because a single band can only have an integer-quantized Hall *** gapless band hosts a zero Hall conductance at low energy but is compensated by another half-quantized Hall conductance at high energy,and thus the half-quantized Hall conductance can only originate from the gapless ***,we calculate the layer-resolved Hall conductance of the *** conclusion suggests that the individual gapped surface band alone does not support the half-quantized surface Hall effect in a lattice model.

关键词： magnetic topological insulator Dirac equation half-quantized Hall conductance

Rational Schur Superalgebras

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Algebra colloquium 2024年第2期31卷 209-220页

作者： Andrew Riesen shun-Jen c.eng Department of Mathematical and Statistical Sciences University of Alberta 1132489 Ave NWEdmontonAlbertaCanada 不详

We develop and study the generalization of rational Schur algebras to the super *** to the classical case,this provides a new method for studying rational supermodules of the general linear supergroup GL(m|n).Furthermore,we establish a Schur-Weyl duality result for rational Schur superalgebras and conclude that under certain conditions these objects will be semisimple.

关键词： Schur algebra supermathematics general linear supergroup

Resilience conferred by APOE-R136S:a defense bestowed by nature to combat Alzheimer’s disease

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Signal Transduction and Targeted Therapy 2024年第3期9卷 831-832页

作者： Bin Xiao Joshua Kuruvilla eng-King Tan Department of Neurology National Neuroscience InstituteSingaporeSingapore Neuroscience Academic clinical Program Duke-NUS Medical SchoolSingaporeSingapore Neuroscience and Behavioural Disorders Program Duke-NUS Medical SchoolSingaporeSingapore

In two recent articles published in Nature Neuroscience and cell,Nelson et al.1 and chen et al.2 have shown that a rare APOE3 christchurch(APOE3ch)variant,R136S,has protective effects on neurodegeneration in various Alzheimer’s disease(AD)model systems through attenuating tau pathology and regulating its related neuroimmune *** et *** chen et *** provided evidence that identifying the pathophysiologic clues and potential molecular targets from a protective variant such as APOE R136S,can be an attractive viable approach to develop AD therapeutics.

关键词： protective al. Alzheimer

A Geometric Based connection between Fractional calculus and Fractal Functions

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Acta Mathematica Sinica,english Series 2024年第2期40卷 537-567页

作者： Yong shun LIANG Wei Yi SU School of Mathematics and Statistic Nanjing University of Science and TechnologyNanjing 210094P.R.China Department of Mathematics Nanjing UniversityNanjing 210023P.R.China

Establishing the accurate relationship between fractional calculus and fractals is an important research content of fractional calculus *** the present paper,we investigate the relationship between fractional calculus and fractal functions,based only on fractal dimension *** dimension of the Riemann-Liouville fractional integral of continuous functions seems no more than fractal dimension of functions *** fractal dimension of the Riemann-Liouville fractional differential of continuous functions seems no less than fractal dimension of functions themselves when they *** further discussion,fractal dimension of the Riemann-Liouville fractional integral is at least linearly decreasing and fractal dimension of the Riemann-Liouville fractional differential is at most linearly increasing for the Holder continuous *** about other fractional calculus,such as the Weyl-Marchaud fractional derivative and the Weyl fractional integral has also been given *** work is helpful to reveal the mechanism of fractional calculus on continuous *** the same time,it provides some theoretical basis for the rationality of the definition of fractional *** is also helpful to reveal and explain the internal relationship between fractional calculus and fractals from the perspective of geometry.

关键词： Fractional calculus fractal functions fractal dimension fractional calculus equation relationship

Thermal oxidation description methodology of thermal barrier coatings on gas turbine blades considering service characteristics

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chinese Journal of Aeronautics 2024年第6期37卷 410-424页

作者： Qiannan TAO Yanrong WANG Dasheng WEI shun YANG School of Energy and Power engineering Beihang UniversityBeijing 100191China Jiangxi Research Institute of Beihang University Nanchang 330096China

Predicting the thickness of Thermally Grown Oxide(TGO)and the residual stresses induced by TGO growth in the Thermal Barrier coatings(TBcs)is significant work in analyzing the failure of *** practical applications,the operating temperature,oxygen partial pressure,aluminium content in TBcs,and porosity of the topcoat affect the oxidation ***,a novel oxidation rate model is proposed to describe the effect of such *** parameters in the proposed model were fitted with isothermal degradation test data from prior ***,a method for calculating the residual stress in a disk-shaped specimen was developed based on the oxidized growth strain model and the oxidized ***,a variable-temperature oxidation experiment was performed to validate the new oxidation *** average error between the predicted and experimental thicknesses is approximately 10%,and the average error between the residual stresses is 30%.Under the variable-temperature condition,the error between the predicted thickness and the average experimental thickness is 3.9%.

关键词： Thermal barrier coatings Oxidation Gas turbine Residual stresses Sintering

Recent advances in morphology control of platinum catalysts toward oxygen reduction reaction

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Frontiers in Energy 2024年第3期18卷 330-355页

作者： shun cHEN Yanru LIU Xiaogang FU Wanglei WANG State Key Laboratory of Solidification Processing Atomic Control and Catalysis Engineering LaboratorySchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration National Clinical Research Center for Oral DiseasesShaanxi Key Laboratory of StomatologyDepartment of Dental MaterialsSchool of StomatologyThe Fourth Military Medical UniversityXi’an 710032China

Exploring advanced platinum (Pt)-based electrocatalysts is vital for the widespread implementation of proton exchange membrane fuel cells (PEMFcs). Morphology control represents an effective strategy to optimize the behavior of Pt catalysts. In this work, an attempt is made to comprehensively review the effect of morphology control on the catalytic behavior of catalysts in the oxygen reduction reaction (ORR). First, the fundamental physicochemical changes behind morphology control, including exposing more active sites, generating appropriate lattice strains, and forming different crystalline surfaces, are highlighted. Then, recently developed strategies for tuning the morphologies of electrocatalysts, including core-shell structures, hollow structures, nanocages, nanowires, and nanosheets, are comprehensively summarized. Finally, an outlook on the future development of morphology control of Pt catalysts is presented, including rational design strategies, advanced in situ characterization techniques, novel artificial intelligence, and mechanical learning. This work is intended to provide valuable insights into designing the morphology and technological innovation of efficient redox electrocatalysts in fuel cells.

关键词： morphology platinum catalysts electrocatalysis ORR PEMFc

Analytical computation of magnetic field in coil-dominated superconducting quadrupole magnets based on racetrack coils

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Nuclear Science and Techniques 2024年第4期35卷 119-135页

作者： chuang Shen Ying-shun Zhu Fu-San chen china Spallation Neutron Source Institute of High Energy PhysicsChinese Academy of Sciences1 Zhongziyuan RoadDongguan 523000China Institute of High Energy Physics Chinese Academy of Sciences19B Yuquan RoadBeijing 100049China University of chinese Academy of Sciences Beijing 100049China

currently,three types of superconducting quadrupole magnets are used in particle accelerators:cos 2θ,ccT,and ***,all three coil configurations have complex spatial geometries,which make magnet manufacturing and strain-sensitive superconductor applications *** with the three existing quadrupole coils,the racetrack quadrupole coil has a simple shape and manufacturing process,but there have been few theoretical *** this paper,the two-dimensional and three-dimensional analytical expressions for the magnetic field in coil-dominated racetrack superconducting quadrupole magnets are *** analytical expressions of the field harmonics and gradient are fully resolved and depend only on the geometric parameters of the coil and current ***,a genetic algorithm is applied to obtain a solution for the coil geometry parameters with field harmonics on the order of 10^(-4).Finally,considering the practical engineering needs of the accelerator interaction region,electromagnetic design examples of racetrack quadrupole magnets with high gradients,large apertures,and small apertures are described,and the application prospects of racetrack quadrupole coils are analyzed.

关键词： Superconducting quadrupole magnet Racetrack coil Multipole field Genetic algorithm Magnetic design

The nitrogen transformation behavior based on the pyrolysis products of wheat straw

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chinese Journal of chemical engineering 2024年第7期71卷 58-65页

作者： shun Guo Yunfei Li Shengwei Tang Tao Zhang School of chemical engineering Sichuan UniversityChengdu 610065China

In order to provide basic design parameters for the industrial pyrolysis process,the transformation behavior of nitrogen was investigated using wheat straw as raw *** distributions of nitrogen in pyrolysis char,oil,and gas were obtained and the nitrogenous components in the products were analyzed systematically by X-ray photoelectron spectroscopy(XPS),pyrolysis-gas chromatography/mass spectrometry(Py-Gc/MS)and thermogravimetric-Fourier transform infrared spectrometry(TG-FTIR).The nitrogen distribution ranges of the pyrolysis char,oil,and gas were 37.34%–54.82%,32.87%–40.94%and 10.20%–28.83%,*** nitrogen was retained in char at lower pyrolysis temperature and the nitrogen distribution of oil was from rise to decline with increasing *** most abundant N-containing compounds in three-phase products were pyrrole-N,amines,and HcN,*** addition,the transformation mechanism of nitrogen from wheat straw to pyrolysis products was concluded.

关键词： Pyrolysis Nitrogen transformation Wheat straw Py-Gc/MS TG-FTIR

Development and application of photocatalytic coating for roadside NO_(x) mitigation in Hong Kong

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chinese chemical Letters 2024年第3期35卷 153-157页

作者： Xinwei Li Pengge Wang Shuwen Han Yu Huang Wingkei Ho Steven Sai Hang Ho shun-c.eng lee Meng Wang Department of civil and Environmental engineering The Hong Kong Polytechnic UniversityHong KongChina State Key Laboratory of Loess and Quaternary Geology(SKLLQG)and Key Laboratory of Aerosol chemistry and Physics Institute of Earth EnvironmentChinese Academy of SciencesXi'an 710061China Department of Science and Environmental Studies The Education University of Hong KongHong KongChina Division of Atmospheric Sciences Desert Research InstituteRenoNV 89512United States

A facile chemical method for the development of photocatalytic coating products was proposed based on practical application perspective for the Hong Kong roadside nitrogen oxides(NO_(x))***_(2)-based photocatalytic coating Pc-c film with crystallized size of around 5–6 nm was synthesized with the peptization of H_(2)O_(2).The Pc-c coating possesses a super-hydrophilicity surface and is proven to have a NO_(x)degradation rate of 46.8%with an optimum pH level of *** addition,the Pc-c coating presents a promising photocatalytic NO_(x)degradation compared with other commercially available coating products and P25 when applied on two building materials of poly-methyl methacrylate(PMMA)and concrete surface.A weather resistance simulation and a 180-day on-site field trial were carried out the attenuation effects of photocatalytic coating applied in outdoor *** on epidemiological estimation and field investigation,hospital admissions for respiratory diseases(HARD)and mortality cases(Mc)could be reduced with the application of Pc-c coating along the street *** work demonstrates the feasibility of air pollution control measures for the local roadside NO_(x)using photocatalytic technology,offering promising health benefits with environmental remediation.

关键词： Photocatalysis coating NO_(x) mitigation Hong Kong Roadside