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分层媒质中的分步相位偏移光声成像方法

声学学报 2024年第3期49卷 392-397页

作者：刘思宇王云石阚威威西南技术物理研究所成都610041 南京理工大学物理学院南京210094

为了解决波场外推方法在横向声速不均匀的分层媒质中图像重建能力受限的问题,提出了一种基于分步相位偏移的不规则分层媒质光声成像方法。该方法将横向声速差异等效为分层媒质界面处的扰动声源,利用该扰动声源对相位偏移的结果进行额外... 详细信息

为了解决波场外推方法在横向声速不均匀的分层媒质中图像重建能力受限的问题,提出了一种基于分步相位偏移的不规则分层媒质光声成像方法。该方法将横向声速差异等效为分层媒质界面处的扰动声源,利用该扰动声源对相位偏移的结果进行额外的校正偏移,并采用变步长的混合外推机制,实现光声波场的逐层外推重建。仿真模拟及实验结果均表明,分步相位偏移方法能够有效抑制不规则分层媒质光声成像中伪影的产生,并提升成像分辨率以及图像对比度。

关键词：光声成像分层媒质成像相位偏移波场外推

Imide-based covalent organic framework with excellent cyclability as an anode material for lithium-ion battery

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Chinese Chemical Letters 2024年第6期35卷 206-210页

作者： Yue Qian Zhoujia Liu Haixin Song Ruize Yin Hanni Yang Siyang Li weiwei Xiong Saisai Yuan Junhao Zhang Huan Pang School of Environmental&Chemical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China School of Chemistry&Chemical Engineering Yangzhou UniversityYangzhou 225009China Shandong Key Laboratory of Biochemical Analysis College of Chemistry and Molecular EngineeringQingdao University of Science and TechnologyQingdao 266042China

Covalent organic frameworks(COFs)exhibiting reversible redox behaviors have been identified as promising candidates for constructing electrode materials in lithium-ion batteries(LIBs).However,their extensive application has been limited due to finite redox sites and poor structural *** this study,we design and synthesize a novel polyimide covalent organic framework(PI-COF)using the traditional solvothermal method and successfully apply it as an anode material for *** large conjugated structure of PI-COF accelerates charge transfer,while its large surface area provides more active sites,making PI-COF an attractive anode material for ***,the PI-COF anode material demonstrates high reversible specific capacity and excellent long-term cycling stability due to its COF ***,the PI-COF electrodes deliver a specific capacity of 800 m Ah/g at a current density of 200 m A/g after 200 cycles,while a specific capacity of 450 m Ah/g at a current density of 1000 m A/g is sustained after 800 *** outstanding lithium storage capacity,particularly the satisfactory long-term cycling stability,establishes PI-COF as a promising material for LIBs.

关键词： Ethylenediaminetetraacetic dianhydride Covalent organic frameworks Polyimide Lithium-ion battery Anode material

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狭缝法测量X射线管焦点尺寸的研究

原子能科学技术 2024年第2期58卷 498-505页

作者：李伟伟王立强郑健清华大学核能与新能源技术研究院北京100084 北京市核检测重点实验室北京100084

目前EN 12543标准中的狭缝法广泛应用于工业用X射线管焦点尺寸的测量和标注。然而所需的测试设备——狭缝相机,由于其复杂和精密的设计要求,导致生产加工难度大、成本高且不利于推广使用。本文采用双钨合金圆柱代替狭缝相机,基于圆柱法... 详细信息

目前EN 12543标准中的狭缝法广泛应用于工业用X射线管焦点尺寸的测量和标注。然而所需的测试设备——狭缝相机,由于其复杂和精密的设计要求,导致生产加工难度大、成本高且不利于推广使用。本文采用双钨合金圆柱代替狭缝相机,基于圆柱法中距离和位置参数校准方法,改进了狭缝法中焦点尺寸测量的计算公式,研究了不同狭缝大小对X射线管焦点尺寸测量的影响和变化规律。实验结果表明,使用间距与焦点尺寸相当的双钨合金圆柱测量COMET公司的MXR-225HP/11工业X射线管,也可以获得较为精确的测量结果,同时实验发现当狭缝宽度较大时,可以直接用来计算焦点测量装置的几何放大倍数,并且计算结果与圆柱法中使用距离和位置参数校准方法所测量的结果相一致。

关键词： X射线管狭缝法圆柱法焦点尺寸

Lightning in a Forest (Wild) Fire: Mechanism at the Molecular Level

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Atmospheric and Climate Sciences 2024年第1期14卷 128-135页

作者： See Leang Chin Xueliang Guo Harmut Schroeder Huanbin Xu Tie-Jun wang Ruxin Li weiwei Liu Department of Physics and Center for Optics Photonics and Lasers (COPL) Laval University Quebec Canada Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Max Planck Institute of Quantum Optics Garching Germany State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai China Institute of Modern Optics Nankai University Tianjin China

The mechanism of lightning that ignites a forest fire and the lightning that occurs above a forest fire are explained at the molecular level. It is based on two phenomena, namely, internal charge separation inside the atmospheric cloud particles and the existence of a layer of positively charged hydrogen atoms sticking out of the surface of the liquid layer of water on the surface of rimers. Strong turbulence-driven collisions of the ice particles and water droplets with the rimers give rise to breakups of the ice particles and water droplets into positively and negatively charged fragments leading to charge separation. Hot weather in a forest contributes to the updraft of hot and humid air, which follows the same physical/chemical processes of normal lightning proposed and explained recently[1]. Lightning would have a high probability of lighting up and burning the dry biological materials in the ground of the forest, leading to a forest (wild) fire. The burning of trees and other plants would release a lot of heat and moisture together with a lot of smoke particles (aerosols) becoming a strong updraft. The condition for creating lightning is again satisfied which would result in further lightning high above the forest wild fire.

关键词： Forest Wild Fire Lightning Molecular Level

Spatial-temporal population dynamics of the critically endangered Blue-crowned Laughingthrush Pterorhinus courtoisi:a 22-year longitudinal study

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Science China(Life Sciences) 2024年第8期67卷 1769-1771页

作者： Tao Liu Jutao He Chang Xiao Jie Liu Jie Sun Minling Li Yuanhua Hong weiwei Zhang Fuwen Wei Jiangxi Provincial Key Laboratory of Conservation Biology Jiangxi Agricultural UniversityNanchang 330045China Forestry Bureau of Wuyuan Shangrao 333299China

Dear Editor,Population size is a crucial indicator in evaluating the conservation status of a *** the patterns of population fluctuation and the distribution range of endangered species is important for biodiversity c... 详细信息

关键词： Population crown dynamics

大型城镇集中安置区搬迁移民生计资本组合对家庭收入影响机理的实证研究

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贵州财经大学学报 2024年第3期 81-91页

作者：汪磊张薇薇汪霞贵州大学经济学院贵州贵阳550025 贵州大学公共管理学院贵州贵阳550025

易地搬迁移民已成为防止规模性返贫的重要群体。当前,搬迁移民面临着就业市场风险增大,生计资本存量减少以及家庭增收困难等现实问题,优化移民生计资本内部结构,发挥生计资本间的组合效应,提升生计资本组合对移民家庭收入的贡献作用是... 详细信息

易地搬迁移民已成为防止规模性返贫的重要群体。当前,搬迁移民面临着就业市场风险增大,生计资本存量减少以及家庭增收困难等现实问题,优化移民生计资本内部结构,发挥生计资本间的组合效应,提升生计资本组合对移民家庭收入的贡献作用是解决上述问题的重要途径。学界当前与易地搬迁相关的研究多聚焦分析移民生计资本对家庭总收入的作用机制,较少基于结构功能理论视角,从实证层面探讨生计资本组合对家庭不同收入来源的影响及其相互作用机制。本文以贵州省大型城镇集中安置区移民为研究对象,首先测算移民家庭生计资本,分别采用OLS和分位数回归分析生计资本与家庭收入之间的作用机理,然后采用多元线性回归模型测算生计资本间的互补效应和替代效应,构建了移民家庭收入与生计资本组合之间的矩阵分析模型,分别应用tobit和logit回归进行实证检验,并剖析了不同维度下不同生计资本组合对不同类型收入的影响。研究结果表明:(1)移民生计资本总量有助于提升家庭收入水平。在后搬迁时代,自然资本对家庭收入的边际贡献最小,而社会资本对家庭收入呈现负向影响。(2)五大资本中的人力资本与自然资本、物质资本、社会资本以及金融资本之间存在着普适性互补效应,金融资本与社会资本间存在替代效应。(3)互补性生计资本值越大,移民家庭工资收入和财产收入越高;互补性和替代性资本量均较低的家庭主要以获得转移性收入维持生计。

关键词：大型城镇集中安置区互补性生计资本替代性生计资本家庭收入结构

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Genetic variation in a heat shock transcription factor modulates cold tolerance in maize

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Molecular Plant 2024年第9期17卷 1423-1438页

作者： Lei Gao Lingling Pan Yiting Shi Rong Zeng Minze Li Zhuoyang Li Xuan Zhang Xiaoming Zhao Xinru Gong Wei Huang Xiaohong Yang Jinsheng Lai Jianru Zuo Zhizhong Gong Xiqing wang weiwei Jin Zhaobin Dong Shuhua Yang State Key Laboratory of Plant Environmental Resilience Frontiers Science Center for Molecular Design BreedingCollege of Biological SciencesCenter for Crop Functional Genomics and Molecular BreedingChina Agricultural UniversityBeijing 100193China State Key Laboratory of Maize Bio-breeding National Maize Improvement CenterFrontiers Science Center for Molecular Design BreedingDepartment of Plant Geneticsand BreedingChinaAgricultural UniversityBeijingChina State Key Laboratory of Plant Genomics and National Plant Gene Research Center Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing100101China

Understanding how maize(Zea mays)responds to cold stress is crucial for facilitating breeding programs of cold-tolerant *** extensive utilization of the genome-wide association study(GWAs)approach for exploring favorable natural alleles associated with maize cold tolerance,few studies have successfully identified candidate genes that contribute to maize cold *** this study,we used a diverse panel of inbred maize lines collected from different germplasm sources to perform a GWAS on var-iations in the relative injured area of maize true leaves during cold stress-a trait very closely correlated with maize cold *** identified HsF21,which encodes a B-class heat shock transcription factor(HSF)that positively regulates cold tolerance at both the seedling and germination *** varia-tions in the promoter of the cold-tolerant HSF21Hap1 allele led to increased HSF21 expression under cold stress by inhibiting binding of the basic leucine zipper bziP68 transcription factor,a negative regulator of cold *** integrating transcriptome deep sequencing,DNA affinity purification sequencing,and targeted lipidomic analysis,we revealed the function of HsF21 in regulating lipid metabolism homeo-stasis to modulate cold tolerance in *** addition,we found that HsF21 confers maize cold tolerance without incurring yield ***,this study establishes HsF21 as a key regulator that en-hances cold tolerance in maize,providing valuable genetic resources for breeding of cold-tolerant maize varieties.

关键词： heat shock factor HSF21 cold tolerance natural variation bZiP68 lipid metabolism maize

Fe_(3)O_(4)-BiOBr/Graphene磁性气凝胶的构筑与Cr(VI)污水净化

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复合材料学报 2024年第4期41卷 1987-1996页

作者：铁伟伟邱帅彪王红霞袁双义董旭何伟伟许昌学院化工与材料学院(表面微纳米材料研究所) 河南省微纳米能量储存与转换材料实验室许昌461000

为改善单一半导体粉体材料的光生电子-空穴分离和回收能力,基于功能协同效应,采用共沉淀法,将Fe^(3+)/Fe^(2+)盐在一定浓度的氨水作用下制备出纳米Fe_(3)O_(4),并分散于含有溴化十六烷基三甲铵(CTAB)的正辛烷中,提供Br-的同时,在室温下... 详细信息

为改善单一半导体粉体材料的光生电子-空穴分离和回收能力,基于功能协同效应,采用共沉淀法,将Fe^(3+)/Fe^(2+)盐在一定浓度的氨水作用下制备出纳米Fe_(3)O_(4),并分散于含有溴化十六烷基三甲铵(CTAB)的正辛烷中,提供Br-的同时,在室温下与水溶液中的硝酸铋和柠檬酸相互作用,利用非互溶体系,制备出Fe_(3)O_(4)-BiOBr;最后,将Fe_(3)O_(4)-BiOBr分散于含有赖氨酸的氧化石墨烯水溶液中,通过一步水热法合成Fe_(3)O_(4)-BiOBr协同修饰的磁性石墨烯气凝胶(Fe_(3)O_(4)-BiOBr/Graphene)。样品的晶体结构、形貌特征和催化活性通过XRD、Raman、XPS、SEM、TEM、UV-Vis光谱等综合测试技术进行了表征分析。Fe_(3)O_(4)-BiOBr/Graphene复合材料中的Fe_(3)O_(4)呈类球状,尺寸约10~25 nm,均匀镶嵌于BiOBr片层中间,并与石墨烯之间相互作用,整体呈现球-片-空洞构造。Fe_(3)O_(4)-BiOBr/Graphene复合材料显示出良好的可见光吸收性和Cr(VI)还原活性,30 min内可去除Cr(VI)至100%,高于单一组分的磁性Fe_(3)O_(4),这可能与Fe_(3)O_(4)-BiOBr异质结构、石墨烯导电材料的引入及Fe_(3)O_(4)-BiOBr/Graphene三者之间良好的界面相互作用,有效地促进了光生电子与空穴的分离效率有关。

关键词：溴氧化铋四氧化三铁石墨烯气凝胶六价铬磁性回收光催化还原

Layered kagome compound Na_(2)Ni_(3)S_(4)with topological flat band

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Chinese Physics B 2024年第5期33卷 153-159页

作者：叶君耀林益浩王浩哲宋志达冯济谢韦伟贾爽 International Center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China Department of Chemistry Michigan State UniversityMI48824USA Hefei National Laboratory Hefei 230088China Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials Peking UniversityBeijing 100871China

We report structural and electronic properties of Na_(2)Ni_(3)S_(4),a quasi-two-dimensional compound composed of alternating layers of[Ni_(3)S_(4)]^(2-)and Na^(+).The compound features a remarkable Ni-based kagome lattice with a square planar configuration of four surrounding S atoms for each Ni *** and electrical measurements reveal a weak paramagnetic insulator with a gap of about 0.5 *** band structure calculation highlights a set of topological flat bands of the kagome lattice derived from the rotated dxz-orbital with C_(3)+T symmetry in the presence of crystal-field splitting.

关键词： kagome lattice flat band