检索结果-南通市图书馆

Tuning Second Chern Number in a Four-Dimensional Topological Insulator by High-Frequency Time-Periodic Driving

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2024年第4期41卷 77-89页

作者：刘峥嵘陈锐周斌 Department of Physics Hubei UniversityWuhan 430062China Key Laboratory of Intelligent Sensing System and Security of Ministry of Education Hubei UniversityWuhan 430062China

Floquet engineering has attracted considerable attention as a promising approach for tuning topological phase *** investigate the effects of high-frequency time-periodic driving in a four-dimensional(4D)topological insulator,focusing on topological phase transitions at the off-resonant quasienergy *** 4D topological insulator hosts gapless three-dimensional boundary states,characterized by the second Chern number C_(2).We demonstrate that the second Chern number of 4D topological insulators can be modulated by tuning the amplitude of time-periodic *** includes transitions from a topological phase with C_(2)=±3 to another topological phase with C_(2)=±1,or to a topological phase with an even second Chern number C_(2)=±2,which is absent in the 4D static ***,the approximation theory in the high-frequency limit further confirms the numerical conclusions.

关键词： topological transitions Periodic

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

在线全文

学校读者我要写书评

暂无评论

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

A STABILITY RESULT FOR TRANSLATINGSPACELIKE GRAPHS IN LORENTZ MANIFOLDS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2024年第2期44卷 474-483页

作者：高雅毛井吴传喜 Faculty of Mathematics and Statistics Key Laboratory of Applied Mathematics of Hubei ProvinceHubei UniversityWuhan430062China

In this paper,we investigate spacelike graphs defined over a domain Ω⊂M^(n) in the Lorentz manifold M^(n)×ℝ with the metric−ds^(2)+σ,where M^(n) is a complete Riemannian n-manifold with the metricσ,Ωhas piecewise smooth boundary,and ℝ denotes the Euclidean *** prove an interesting stability result for translating spacelike graphs in M^(n)×ℝ under a conformal transformation.

关键词： mean curvature flow spacelike graphs translating spacelike graphs maximal spacelike graphs constant mean curvature Lorentz manifolds

Host-induced silencing of MpPar6 confers Myzus persicae resistance in transgenic rape plants

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2024年第1期23卷 187-194页

作者： Qi Zhang Wenqin Zhan Chao Li Ling Chang Yi Dong Jiang Zhang State Key Laboratory of Biocatalysis and Enzyme Engineering School of Life SciencesHubei UniversityWuhan 430062China Oil Crops Research Institute Chinese Academy of Agricultural SciencesWuhan 430062China Agricultural Genomics Institute at Shenzhen Chinese Academy of Agricultural SciencesShenzhen 518000China

Plant-mediated RNA interference(RNAi)has emerged as a promising technology for insect *** green peach aphid,Myzus persicae,feeds on over 400 species of host *** napus(rape)is the second most important oilseed crop *** persicae is highly reproductive and causes severe damage to the rape plants due to its quite flexible life *** this study,we tested the RNAi effects of transgenic rape plants on *** in vitro feeding *** with artificial diets containing double-stranded RNAs(dsRNAs)targeting seven aphid genes,we identified a new gene encoding the partitioning-defective protein 6(Par6)as the most potent RNAi ***-and stage-expression analysis of Par6 suggested this gene is highly expressed in the embryo and adult stage of *** next generated transgenic rape plants expressing ds Par6 by Agrobacteriummediated transformation and obtained nine independent transgenic *** to wild-type control plants,transgenic rape lines expressing ds Par6 showed strong resistance to *** assays revealed that feeding transgenic rape plants to *** significantly decreased MpPar6 expression and survival rate and impaired ***,we showed that the resistance levels to *** are positively correlated with ds Par6 expression levels in transgenic rape *** study demonstrates that transgenic rape plants expressing ds Par6 are efficiently protected from *** with the genes involved in embryo development could be the effective RNAi targets for controlling aphids and potentially other insect pests.

关键词： oilseed rape pest control aphid double-stranded RNA RNA interference

Surface engineering of carbon dots for highly sensitive α-glucosidase assay and inhibition evaluation

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第3期35卷 193-197页

作者： Meijuan Liang Gege Song Yeqing Wan Yingying Chen Fuan Wang Xiaoqing Liu College of Chemistry and Molecular Sciences Wuhan UniversityWuhan 430072China Oil Crops Research Institute Chinese Academy of Agricultural SciencesWuhan 430062China

Monitoringα-glucosidase(α-Glu)activity is of great significance for the early diagnosis of typeⅡ*** the blue fluorescent carbon dots(CDs)were integrated with two different recognizing molecules,β-cyclodextrin and phenylboronic acid,for assembling a multifunctional CDs(mCDs)nanoplatform for sensitively analyzingα-Glu and its *** hydrolyzed product of 4-nitrophenyl-α-D-glucopyranoside(α-Glu substrate),p-nitrophenol,could efficiently quench the fluorescence of mCDs due to its cooperative molecular recognition withβ-cyclodextrin and phenylboronic *** mCDs could be utilized for the detection ofα-Glu activity with the limit of detection of 0.030 U/***,the presentα-Glu detection platform revealed a high selectivity,and other natural enzymes showed scarcely any effect on the present mCDs *** proposed method could be facilely used to screenα-Glu inhibitors with satisfying *** rational mCDs is expected to supplement more comprehensive biosensing platforms for highly sensitive and specific recognition of disease-relevant biomarkers with clinical importance.

关键词： α-Glucosidase Carbon dots Fluorescent sensor Inhibitor β-Cyclodextrin

Ag_(2)Sb合金单层上多层酞菁氧钒分子的组装

在线全文

学校读者我要写书评

暂无评论

物理学报 2024年第11期73卷 80-88页

作者：李小雨彭兰沁赵涵幸运邓炎滔于迎辉湖北大学物理学院武汉430062

利用低温扫描隧道显微镜(STM)研究了各种覆盖度下酞菁氧钒(VOPc)分子在Ag_(2)Sb/Ag(111)上的吸附行为和组装结构.不同于Ag(111)表面,当分子覆盖度在一个单层之内,吸附的VOPc分子均组装为有序的薄膜,呈现出规则排列的空隙和正方形单胞.... 详细信息

利用低温扫描隧道显微镜(STM)研究了各种覆盖度下酞菁氧钒(VOPc)分子在Ag_(2)Sb/Ag(111)上的吸附行为和组装结构.不同于Ag(111)表面,当分子覆盖度在一个单层之内,吸附的VOPc分子均组装为有序的薄膜,呈现出规则排列的空隙和正方形单胞.通过扫描亚分子分辨的STM形貌图,揭示了正方形单胞由一个中心分子和四个对称排列的角分子组成;所有VOPc分子均采用O-up构型,并呈现出两种吸附取向,分子横轴相对于单胞侧边分别旋转约11°和21°.因分子间的偶极-偶极相互作用,进一步沉积的VOPc分子组装为具有O-down和O-up构型交替堆积的分子膜,在分子层内分子轨道沿π堆积方向发生重叠.该研究为调控金属表面功能有机分子组装膜的结构和组装行为提供了一种新途径.

关键词：酞菁氧钒扫描隧道显微镜结构方向

铜氧化层上钒氧酞菁分子的吸附构型及组装结构

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

物理学报 2024年第12期73卷 118-125页

作者：彭兰沁李小雨幸运赵涵邓炎滔于迎辉湖北大学物理学院武汉430062

近年来,有机功能分子的调控因其在提高纳米光电器件内部载流子迁移率方面的突出贡献,已逐渐成为材料科学的热门领域之一.本文利用低温扫描隧道显微镜系统地研究了钒氧酞菁(VOPc)分子在干净Cu(110)和铜氧化层表面的吸附构型和组装结构.在... 详细信息

近年来,有机功能分子的调控因其在提高纳米光电器件内部载流子迁移率方面的突出贡献,已逐渐成为材料科学的热门领域之一.本文利用低温扫描隧道显微镜系统地研究了钒氧酞菁(VOPc)分子在干净Cu(110)和铜氧化层表面的吸附构型和组装结构.在Cu(110)表面,初始时VOPc分子孤立吸附且氧原子向上和向下的构型共存.而在CuO-(2×1)表面,VOPc分子在初始时形成扩展的分子链,随后组装为有序的分子膜,在分子膜中两种吸附构型仍然共存且随机排布.在Cu_(5)O_(6)-c(6×2)表面,初始时VOPc分子的两种构型共存且形成无序结构.在覆盖度接近一个单层时,结构有序的组装分子膜逐渐形成,此时主要采用氧原子向上的分子构型,因偶极相互作用,随后的分子层生长遵循两种分子构型交替堆垛.研究还发现当Cu(110)表面上两种氧化结构共存时,第2层分子更倾向于吸附在Cu_(5)O_(6)-c(6×2)表面担载的分子膜上,主要是由分子层间的偶极相互作用导致的.本研究表明金属表面的氧化层在改变分子吸附构型和组装结构方面的重要性,可能将影响电子器件制造中分子膜中的电荷输运过程.

关键词：钒氧酞菁铜氧化层扫描隧道显微镜分子组装

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

基于二维磁性材料的自旋轨道力矩研究进展

物理学报 2024年第1期73卷 46-56页

作者：熊宜浓吴闯文任传童孟德全陈是位梁世恒湖北大学物理与电子科学学院武汉430062 智能感知系统与安全教育部重点实验室武汉430062

信息技术的高速发展对信息处理与存储器件的性能提出了更高的要求.同时,随着器件尺寸不断减小,传统基于电子电荷属性的半导体器件面临热耗散和量子尺寸效应的难题与挑战,半导体技术也由此进入后摩尔时代.区别于传统基于电荷的电子器件,... 详细信息

信息技术的高速发展对信息处理与存储器件的性能提出了更高的要求.同时,随着器件尺寸不断减小,传统基于电子电荷属性的半导体器件面临热耗散和量子尺寸效应的难题与挑战,半导体技术也由此进入后摩尔时代.区别于传统基于电荷的电子器件,基于自旋属性的非易失性自旋电子器件不但具有较高的集成度、读写速度及读写次数,而且可有效避免热耗散,为信息存储、处理和通信等领域的发展构建了新的技术平台.近年来,二维材料凭借其独特的能带结构和丰富的物理性质而备受关注,特别是二维磁性材料体系在自旋电子学领域展现出极大的研究潜力和应用价值.本文首先介绍了二维材料常见制备方法,聚焦概述了二维磁性材料在自旋轨道电子学领域中的研究进展,最后对本领域研究进行了展望.

关键词：自旋电子学二维磁性材料自旋轨道力矩

维普期刊数据库博看期刊

基于正负核密度曲线的线要素局部清晰度估算与自适应分段

在线全文

学校读者我要写书评

暂无评论

测绘学报 2024年第6期53卷 1180-1194页

作者：成晓强刘娜湖北大学资源环境学院湖北武汉430062 区域开发与环境响应湖北省重点实验室湖北武汉430062

在线要素化简时,根据特征差异对线要素进行分段是合理运用化简方法的关键。然而现有分段方法侧重分析线要素的形态特征,忽略了线要素在不同比例尺表达的视觉差异。线要素中无法清晰辨识的模糊部位会随比例尺的变化而改变。基于此,本文... 详细信息

在线要素化简时,根据特征差异对线要素进行分段是合理运用化简方法的关键。然而现有分段方法侧重分析线要素的形态特征,忽略了线要素在不同比例尺表达的视觉差异。线要素中无法清晰辨识的模糊部位会随比例尺的变化而改变。基于此,本文提出了一种基于局部清晰度的线要素分段方法。首先,在特定比例尺下生成线要素的栅格形态,并将栅格线像素分为3类:单边界像素、双边界像素和内部像素,其中单边界像素和内部像素会严重影响线要素的视觉辨识;其次,建立3类像素与原矢量折点的映射关系,得到两组数据点:对应线要素模糊部位的粘连折点和对应线要素清晰部位的正常折点;然后,基于一维核密度进行两组数据点的聚集性分析,分别生成该尺度下表示线要素清晰度变化的正向核密度曲线和表示线要素模糊程度变化的负向核密度曲线;最后,分析正负核密度交点特征,得到划分线要素清晰与模糊区域的分段点并完成线要素分段。通过与人为分段结果对比可知,本文的分段结果与人眼对线要素模糊与清晰部分的识别基本一致。

关键词：多尺度异质性线要素局部清晰度核密度线要素分段