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Phase transition of multi-component(TiZrVNb)C ceramics—Part II:From single phase to multiple phases via adjusting V content

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Journal of Advanced Ceramics 2024年第5期13卷 689-698页

作者： Qingyi Kong Lei chen Sijia Huo Kunxuan Li Wenyu Lu yujin Wang Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China Key Laboratory of Advanced Structure‒Function Integrated Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China National Key Laboratory of Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China

To address the relatively mediocre mechanical properties of single-phase multi-component carbide ceramics,a phase transition from a single phase to multiple phases was proposed to achieve superior mechanical properties.A series of(TiZrVxNb)C0.8 ceramics with different V contents were fabricated by spark plasma sintering(SPS).The influence of the V content on the phase composition,microstructural evolution,and mechanical properties was investigated in detail.The transition behavior from a single phase to multiple phases is discovered and discussed.The formation of the Zr-rich phase and Zr-poor phase can be attributed to the increase in lattice distortion and mixed enthalpy caused by the addition of V.A nanometer lamellar structure with a semi-coherent interface obtained via in situ decomposition is reported for the first time in multi-component carbide ceramics.The semi-coherent interfaces with high dislocation density and strain concentration effectively improve the mechanical properties,grain refinement,and multi-phase formation.The optimal comprehensive mechanical properties of the Vickers hardness(26.3 GPa),flexural strength(369 MPa),and fracture toughness(3.1 MPa·m1/2)were achieved for the sample with 20 mol%V.

关键词： multi-component ceramics multiple phases microstructure evolution phase decomposition mechanical properties

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Phase transition of multi-component(TiZrVNb)C ceramics—Part I:Phase decomposition induced by carbon content

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Journal of Advanced Ceramics 2024年第5期13卷 679-688页

作者： Qingyi Kong Rao Zhang Lei chen Sijia Huo Wenyu Lu yujin Wang Boxin Wei Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China Key Laboratory of Advanced Structure‒Function Integrated Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Chemical Engineering Harbin University of Science and TechnologyHarbin 150001China National Key Laboratory of Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China

Phase decomposition can effectively enhance the mechanical properties of carbide ceramics and can overcome the difficulty of enhancing the mechanical properties of single-phase multicomponent carbide ceramics.In this work,a series of nonstoichiometric(TiZrVNb)Cx ceramics were prepared by spark plasma sintering(SPS)at different temperatures.The effects of the carbon content on the phase composition,microstructure evolution,and mechanical properties were investigated in detail.Phase decomposition occurred with decreasing carbon content.Two different solid solutions of(Ti,V)-rich and Zr-rich phases formed from the decomposition of equimolar single-phase solid solutions,namely,the Zr-poor phase and Zr-rich phase,respectively.The distribution of Nb element is relatively uniform.The semicoherent interfaces between the Zr-poor phase and the Zr-rich phase can harden and strengthen effectively under the synergistic effect of grain refinement.Ceramics with phase decomposition structures have apparent advantages compared to single-phase high-entropy carbides.This work provides an important train of thought for the microstructure tailoring and properties optimization of multi-component carbide ceramics.

关键词： multicomponent ceramics nontoichiometry microstructure evolution phase decomposition mechanical properties

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Circular RNA circ_0003609 ameliorates hypertrophied ligamentum flavum by regulating the miR-155/SIRT1 axis

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BIOCELL 2024年第6期48卷 1001-1008页

作者： GUIBIN ZHONG SHURONG WANG yujin HE DAMING FENG KE WEI YANQIU YANG JIANWEI chen JUNLING chen Department of Orthopaedics Baoshan BranchRen Ji HospitalSchool of Medicine Shanghai Jiao Tong UniversityShanghai200444China Department of Orthopaedics Ren Ji HospitalSchool of Medicine Shanghai Jiao Tong UniversityShanghai200127China Department of Operation and Anaesthesia Ren Ji HospitalSchool of Medicine Shanghai Jiao Tong UniversityShanghai200127China Department of Orthopaedics Huai Yuan Chang Jiu HospitalHuaiyuan233499China

Background:Hypertrophy of the ligamentumﬂavum(HLF)is a common contributor to spinal stenosis which results in signiﬁcant neurological impairments.Circular RNA(circRNA)circ_0003609 has been linked to HLF;however,the exact mechanism by which it causes this disease is unclear.Methods:Circ_0003609 expressions were regulated in HLF cells by overexpression vectors and RNA interference.Cell proliferation andﬁbrosis-related gene expression were checked by the Cell Counting Kit-8(CCK-8)assay and western blotting.CircBank’s prediction of the association between miR-155 and circ_0003609 was supported by a dual-luciferase reporter experiment.The function of the miR-155/sirtuin 1(SIRT1)axis in controlling HLFﬁbrosis was further examined.Results:Overexpression of circ_0003609 suppressed HLF cell propagation andﬁbrosis compared to its silencing.It was found that circ_0003609 served as the sponge for miR-155 and that the circ_0003609/miR-155 axis controlled theﬁbrosis of HLF cells.It was found that circ_0003609 acted as a sponge for miR-155,regulating theﬁbrosis of HLF cells.Further,miR-155 targets SIRT1,and the miR-155/SIRT1 axis promotes HLF cellﬁbrosis.Conclusion:Circ_0003609 ameliorates hypertrophied ligamentumﬂavum(LF)by modulating the miR-155/SIRT1 axis,indicating a potential treatment approach for HLF.

关键词： Circular RNA Circ_0003609 Hypertrophy of ligamentum flavum MiR-155 Sirtuin 1 Fibrosis

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Multi-scale attention encoder for street-to-aerial image geo-localization

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CAAI Transactions on Intelligence Technology 2023年第1期8卷 166-176页

作者： Songlian Li Zhigang Tu yujin chen Tan Yu State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina Department of Informatics Technical University of MunichGarchingGermany Baidu USA SunnyvaleCaliforniaUSA

The goal of street-to-aerial cross-view image geo-localization is to determine the location of the query street-view image by retrieving the aerial-view image from the same place.The drastic viewpoint and appearance gap between the aerial-view and the street-view images brings a huge challenge against this task.In this paper,we propose a novel multiscale attention encoder to capture the multiscale contextual information of the aerial/street-view images.To bridge the domain gap between these two view images,we first use an inverse polar transform to make the street-view images approximately aligned with the aerial-view images.Then,the explored multiscale attention encoder is applied to convert the image into feature representation with the guidance of the learnt multiscale information.Finally,we propose a novel global mining strategy to enable the network to pay more attention to hard negative exemplars.Experiments on standard benchmark datasets show that our approach obtains 81.39%top-1 recall rate on the CVUSA dataset and 71.52%on the CVACT dataset,achieving the state-of-the-art performance and outperforming most of the existing methods significantly.

关键词： global mining strategy image geo-localization multiscale attention encoder street-to-aerial cross-view

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Identification of the Intrinsic Dielectric Properties of Metal Single Atoms for Electromagnetic Wave Absorption

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Nano-Micro Letters 2022年第2期14卷 107-123页

作者： Xinci Zhang Yanan Shi Jia Xu Qiuyun Ouyang Xiao Zhang Chunling Zhu Xiaoli Zhang yujin chen Key Laboratory of In‑Fiber Integrated Optics College of Physics and Optoelectronic EngineeringHarbin Engineering UniversityHarbin 150001People’s Republic of China College of Materials Science and Chemical Engineering Harbin Engineering UniversityHarbin 150001People’s Republic of China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001People’s Republic of China

Atomically dispersed metals on N-doped carbon supports(M-N_(xCs)) have great potential applications in various fields.However,a precise understanding of the definitive relationship between the configuration of metal single atoms and the dielectric loss properties of M-N_(xCs) at the atomic-level is still lacking.Herein,we report a general approach to synthesize a series of three-dimensional(3D)honeycomb-like M-N_xC(M=Mn,Fe,Co,Cu,or Ni) containing metal single atoms.Experimental results indicate that 3D M-N_(xCs) exhibit a greatly enhanced dielectric loss compared with that of the NC matrix.Theoretical calculations demonstrate that the density of states of the d orbitals near the Fermi level is significantly increased and additional electrical dipoles are induced due to the destruction of the symmetry of the local microstructure,which enhances conductive loss and dipolar polarization loss of 3D M-N_(xCs),respectively.Consequently,these 3D M-N_(xCs) exhibit excellent electromagnetic wave absorption properties,outperforming the most commonly reported absorbers.This study systematically explains the mechanism of dielectric loss at the atomic level for the first time and is of significance to the rational design of high-efficiency electromagnetic wave absorbing materials containing metal single atoms.

关键词： Metal single atoms Dielectric loss behavior NaCl-templating method Lightweight absorbers Honeycomb-like N-doped nanocarbons

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MINIMIZERS OF L^(2)-SUBCRITICAL VARIATIONAL PROBLEMS WITH SPATIALLY DECAYING NONLINEARITIES IN BOUNDED DOMAINS

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Acta Mathematica Scientia 2024年第3期44卷 984-996页

作者：陈彬高永帅郭玉劲吴越 School of Mathematics and Statistics Hubei key Laboratory of Mathematical SciencesCentral China Normal UniversityWuhan430079China

This paper is concerned with the minimizers of L^(2)-subcritical constraint variar tional problems with spatially decaying nonlinearities in a bounded domain Ω of R~N(N≥1).We prove that the problem admits minimizers... 详细信息

关键词： decaying nonlinearity L~2-subcritical minimizers bounded domains mass concentration

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Regulation of impedance matching feature and electronic structure of nitrogen-doped carbon nanotubes for high-performance electromagnetic wave absorption

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Journal of Materials Science & Technology 2022年第13期108卷 1-9页

作者： Fenghui Cao Jia Xu Minjie Liu Feng Yan Qiuyun Ouyang Xitian Zhang Xiaoli Zhang yujin chen Key Laboratory of In-Fiber Integrated Optics College of Physics and Optoelectronic EngineeringHarbin Engineering UniversityHarbin 150001China School of Mechatronic Engineering Daqing Normal UniversityDaqing 163712China Key Laboratory for Photonic and Electronic Bandgap Materials Ministry of Educationand School of Physics and Electronic EngineeringHarbin Normal UniversityHarbin 150025China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

In this study,we developed a facile method to fabricate three-dimensional(3D)structures composed of FeNi alloy nanoparticles encapsulated in N-doped carbon nanotubes that grafted on the SiO_(2) spheres(Fe_(x)Ni_(y)@NCNT@SiO_(2))for electromagnetic wave(EMW)absorption.The experimental results suggest that the impedance matching characteristic can be tuned by the introduction of SiO_(2) spheres in the 3D structure.Density functional theory(DFT)calculations showed that the introduction of Ni improved the polarization and conductive losses of the Fe_(x)Ni_(y)@NCNT@SiO_(2).As a result,the optimal 3D structure exhibits excellent EMW absorption property with a reflection loss and effective absorption bandwidth are-49.39 dB and 4.32 GHz,respectively,even though the matching thickness is only 1.6 mm,superior to most magnetic carbon-based composites.Thus,our current approach opens up an effective way to the development of low-cost,high-performance EMW absorbers.

关键词： FeNi alloy CNTs Silica Nitrogen doping Electromagnetic wave absorption

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Luminescence properties of phosphate phosphors Ba3Gd1-x(PO4)3：xSm^3＋

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Journal of Rare Earths 2018年第5期36卷 456-460页

作者： Honghui Li Xinghong Gong yujin chen Jianhua Huang Yanfu Lin Zundu Luo Yidong Huang Key Laboratory of Optoelectronic Materials Chemistry and Physics Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou 350002 China Fujian Normal University Fuzhou 350007 China

A series of reddish orange phosphors Ba3Gd1-x（PO4）3：xSm^3＋（x = 0.02, 0.04 0.12） were prepared by the high-temperature solid-state reaction. X-ray powder diffraction （XRD） and diffuse reflectance and photoluminescence spectra were utilized to characterize the structure and spectral properties of the phosphors. The phosphors have strong absorption in the near-UV region. CIE chromaticity coordinates of the phosphors are located in the reddish orange region since the strongest emission band is around 598 nm and related to the 4G5/2 - 6H7/2 transition of Sm^3＋. Optimal concentration of Sm^3＋ in the phosphors is about 6.0 at%. The quantum yield of the Ba3Gdo.94（PO4）3：0.06Sm^3＋ under excitation at 403 nm is about 52.07%. Temperature dependent photoluminescence spectra of the Ba3Gdo.94（PO4）3：0.06Sm^3＋ were measured and the phosphor exhibits high thermal stability of emission. All the results show that the Ba3Gd（PO4）3：Sm^3＋ phosphor may be a potential red phosphor for near-UV based white LEDs.

关键词： Ba3Gd（PO4）3 Sm^3＋ phosphor Photoluminescence Reddish orange Rare earths

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杭州湾北岸现代潮滩沉积物粒度特征及其对古海平面的指示意义

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地质通报 2024年第4期43卷 516-526页

作者：战庆赵宝成陈昆钰史玉金王寒梅上海市地质调查研究院上海200072 自然资源部地面沉降监测与防治重点实验室上海200072 上海地面沉降控制工程技术研究中心上海200072 上海中学国际部上海200231

对杭州湾北岸3处现代潮滩沉积物进行高精度粒度分析,查找研究区潮滩不同微相的粒度特征和差异,提取基于粒度分析的潮滩微相识别敏感指标,并将其应用到该区域的全新世钻孔潮滩沉积物中,识别钻孔潮滩沉积微相,据此建立研究区全新世早期的... 详细信息

对杭州湾北岸3处现代潮滩沉积物进行高精度粒度分析,查找研究区潮滩不同微相的粒度特征和差异,提取基于粒度分析的潮滩微相识别敏感指标,并将其应用到该区域的全新世钻孔潮滩沉积物中,识别钻孔潮滩沉积微相,据此建立研究区全新世早期的海平面曲线。研究表明:杭州湾北岸现代高潮滩盐沼沉积物粘土含量明显高于高潮滩下部和中潮滩,而砂含量与之相反;高潮滩盐沼平均粒径等粒度参数明显小于中、高潮滩的粒度参数;盐沼沉积物粒度频率曲线峰态宽缓,明显区别于高潮滩下部和中潮滩。上述现代潮滩微相粒度敏感指标可成功应用到钻孔潮滩沉积微相划分中,并建立了该区域全新世早期海平面曲线。曲线显示,9700~8700 cal a BP期间海平面上升约11.6 m,海平面上升速率可达1.2 cm/a。现代潮滩不同位置沉积物粒度参数的规律性差异可作为潮滩微相识别的有效指标,为古潮滩沉积微相识别和古海平面重建提供参考依据。

关键词：粒度分析敏感指标潮滩微相海平面杭州湾北岸

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平邑甜茶根系及mhp-miR164a对根区压力的响应

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植物生理学报 2024年第2期60卷 331-338页

作者：程玉瑾陈冰荀咪朱晓悦张玮玮杨洪强山东农业大学园艺科学与工程学院山东泰安271018

本研究以平邑甜茶(Malus hupehensis var.pingyiensis)幼苗和转mhp-miR164a拟南芥为试材,在砂培条件下,通过根区加压,分析根系变化和mhp-miR164a的作用。结果表明,根区加压显著改变平邑甜茶和拟南芥根系形态结构。根区加压下调平邑甜茶... 详细信息

本研究以平邑甜茶(Malus hupehensis var.pingyiensis)幼苗和转mhp-miR164a拟南芥为试材,在砂培条件下,通过根区加压,分析根系变化和mhp-miR164a的作用。结果表明,根区加压显著改变平邑甜茶和拟南芥根系形态结构。根区加压下调平邑甜茶根系mhp-miR164a的表达,压力54~90 kPa显著抑制平邑甜茶主根生长,促进其侧根形成。未加压条件下,过表达mhp-miR164a拟南芥侧根数显著低于野生型。对根区施加54 kPa压力后,与对照相比,野生型拟南芥的侧根数显著增加,过表达mhp-miR164a拟南芥的主根长和侧根数均显著降低,且显著低于加压下野生型的主根长和侧根数。过表达mhp-miR164a拟南芥对高硬度培养基穿透能力显著降低。这些结果表明mhp-miR164a负调控平邑甜茶侧根发生及根系抵抗根区压力的能力。

关键词：平邑甜茶根系 mhp-miR164a 根区压力

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