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An inorganic liquid crystalline dispersion with 2D ferroelectric moieties

National Science Review 2024年第5期11卷 254-263页

作者： Ziyang Huang Zehao Zhang Rongjie Zhang Baofu Ding Liu Yang Keyou wu Youan Xu Gaokuo Zhong Chuanlai Ren Jiarong Liu Yugan Hao menghao wu Teng Ma Bilu Liu Shenzhen Graphene Centre Shenzhen Key Laboratory of Advanced Layered Materials for Value-added ApplicationsTsinghua-Berkeley Shenzhen Institute and Institute of Materials ResearchTsinghua Shenzhen International Graduate School Tsinghua University Institute of Technology for Carbon Neutrality Faculty of Materials Science and Engineering Shenzhen Institute of Advanced Technology Chinese Academy of Sciences School of Physics and Institute for Quantum Science and Engineering School of Chemistry and Institute of Theoretical ChemistryHuazhong University of Science and Technology Xi'an Research Institute of High Technology Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Department of Applied Physics Hong Kong Polytechnic University

Electro-optical effect-based liquid crystal devices have been extensively used in optical modulation techniques, in which the Kerr coefficient reflects the sensitivity of the liquid crystals and determines the strength of the device's operational electric field. The Peterlin–Stuart theory and the O'Konski model jointly indicate that a giant Kerr coefficient could be obtained in a material with both a large geometrical anisotropy and an intrinsic polarization, but such a material is not yet reported. Here we reveal a ferroelectric effect in a monolayer two-dimensional mineral vermiculite. A large geometrical anisotropy factor and a large inherent electric dipole together raise the record value of Kerr coefficient by an order of magnitude, till 3.0 × 10-4mV-2. This finding enables an ultra-low operational electric field of10～2–10～4V m-1and the fabrication of electro-optical devices with an inch-level electrode separation, which has not previously been practical. Because of its high ultraviolet stability（decay <1% under ultraviolet exposure for 1000 hours）, large-scale production, and energy efficiency, prototypical displayable billboards have been fabricated for outdoor interactive scenes. This work provides new insights for both liquid crystal optics and two-dimensional ferroelectrics.

关键词： 2D materials layered minerals vermiculite ferroelectric inorganic liquid crystal Kerr coefficient

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Ultra-high piezoelectric coefficients and strain-sensitive Curie temperature in hydrogen-bonded systems

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National Science Review 2021年第3期8卷 62-69页

作者： Yangyang Ren menghao wu Jun-Ming Liu School of Physics Huazhong University of Science and Technology Laboratory of Solid State Microstructures Nanjing University

We propose a new approach to obtain ultra-high piezoelectric coefficients that can be infinitely large theoretically,where ferroelectrics with strain-sensitive Curie temperature are *** show the first-principles plus Monte Carlo simulation evidence that many hydrogen-bonded ferroelectrics(*** PhMDA) can be ideal candidates,which are also flexible and *** to the specific features of hydrogen bonding,their proton hopping barrier will drastically increase with prolonged proton transfer distance,while their hydrogen-bonded network can be easily compressed or stretched due to softness of hydrogen *** barriers as well as the Curie temperature can be approximately doubled upon a tensile strain as low as 2%.Their Curie temperature can be tuned exactly to room temperature by fixing a strain in one direction,and in another direction,an unprecedented ultra-high piezoelectric coefficient of 2058 pC/N can be *** value is even underestimated and can be greatly enhanced when applying a smaller *** from sensors,they can also be utilized for converting either mechanical or thermal energies into electrical energies due to high pyroelectric coefficients.

关键词： hydrogen-bonded ferroelectrics strain-sensitive Curie temperature ultra-high piezoelectric coefficient first-principles calculations Monte Carlo simulations

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Room-temperature multiferroicity and diversified magnetoelectric couplings in 2D materials

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National Science Review 2020年第2期7卷 373-380页

作者： Tingting Zhong Xiaoyong Li menghao wu Jun-Ming Liu School of Physics and wuhan National High Magnetic Field Center Huazhong University of Science and Technology Laboratory of Solid State Microstructures Nanjing University

Multiferroics are rare in nature due to the mutual exclusive origins of magnetism and ferroelectricity. The simultaneous coexistence of robust magnetism/ferroelectricity and strong magnetoelectric coupling in single multiferroics is hitherto unreported, which may also be attributed to their potential conflictions. In this paper, we show the first-principles evidence of such desired coexistence in ultrathin-layer CuCrS2and CuCrSe2. The vertical ferroelectricity is neither induced by an empty d shell nor spin-driven, giving rise to an alternative possibility of resolving those intrinsic exclusions and contradictions. Compared with their bulk phases, the ferromagnetism in the thin-layer structures(two–six layers) can be greatly stabilized due to the enhanced carrier density and orbital shifting by vertical polarization, and the Curie temperatures of both ferromagnetism and ferroelectricity can be above room temperature. Moreover, a considerable net magnetization can be reversed upon ferroelectric switching, where the change in spin-resolved band structure also renders efficient ‘magnetic reading + electrical writing’. The thickness-different layers may even exhibit diversified types of magnetoelectric coupling, which both enriches the physics of multiferroics and facilitates their practical applications.

关键词： 2D multiferroics room-temperature ferromagnetism and ferroelectricity diversified magnetoelectric couplings vertical polarizations first-principles calculations

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Constructing Stable and Potentially High-Performance Hybrid Organic-Inorganic Perovskites with“Unstable”Cations

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Research 2020年第1期2020卷 228-237页

作者： Qing Yang menghao wu Xiao Cheng Zeng School of Physics Huazhong University of Science and TechnologyWuhanHubei 430074China Department of Chemistry University of NebraskaLincolnNE 68588USA

A new family of functional hybrid organic-inorganic perovskites(HOIPs)is theoretically designed based on the following chemical insights:when a proton is adhered to molecules like water or ethanol,the newly formed larger-sized cations(e.g.,H_(5)O_(2)^(+),C_(2)H_(5)OH_(2)^(+),and CH_(3)SH^(+))entail low electron affinities mimicking superalkalis;they are conjugated acids of weak bases that cannot survive in solution,while their chemistry behavior in the HOIP frameworks,however,may be markedly different due to greatly enhanced cohesive energies of the proton,which facilitate the formation of new ***-principles computations show that the putative formation reactions for these newly designed HOIPs typically release much more energy compared with the prevailing HOIP MAPbI3,suggesting the likelihood of facile solution-based fabrications,while the suppression of reverse formation suggests that the humidity stability may be markedly *** their formations,halide acids are unlikely to react with ethanol or methanethiol without the presence of metal halides,a condition further favoring their *** proposed structure of(H_(5)O_(2))PbI_(3)may also clarify the origin of the long-speculated existence of ***,density functional theory computations suggest that many of these HOIPs possess not only direct bandgaps with values within the optimal range for solar light absorbing but also more desirable optical absorption spectra than that of MAPbI3,where their ferroelectric polarizations also benefit *** stability and photovoltaic efficiency may be even further improved for the newly designed two-dimensional(2D)HOIPs and 2D/3D hybrid HOIP structures.

关键词： stability. stability bases

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Inorganic Nanoribbons with Unpassivated Zigzag Edges： Half Metallicity and Edge Reconstruction

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Nano Research 2011年第2期4卷 233-239页

作者： menghao wu Xiaojun wu Yong Pei Xiao Cheng Zeng Department of Chemistry and Department of Physics and Astronomy University of Nebraska-Lincoln Lincoln Nebraska 68588 USA Department of Materials of Science and Engineering Hefei National Laboratory for Physical Materials at M icroscale University of Science and Technology of China Hefei Anhui 230026 China Key Laboratory of Environnlentally Friendly Chemistry and Application of Ministry of Education Xiangtan University Xiangtan 411105 China）

We have investigated the electronic and structural properties of inorganic nanoribbons （BN, AIN, GaN, SiC, and ZnO） with unpassivated zigzag edges using density functional theory calculations. We find that, in general, the unpassivated zigzag edges can lead to spin-splitting of energy bands. More interestingly, the inorganic nanoribbons A1N and SiC with either one or two edges unpassivated are predicted to be half metallic. Possible structural reconstruction at the unpassivated edges and its effect on the electronic properties are investigated. The unpassivated N edge in the BN nanoribbon and P edge in the AlP nanoribbon are energetically less stable than the corresponding reconstructed edge. Hence, edge reconstruction at the two edges may occur at high temperatures. Other unpassivated edges of the inorganic nanoribbons considered in this study are all robust against edge reconstruction.

关键词： A1N and SiC nanoribbons half metallicit unpassivated zigzag edge edge reconstruction density functional theory

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Single-phase multiferroics: new materials, phenomena,and physics

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National Science Review 2019年第4期6卷 653-668页

作者： Chengliang Lu menghao wu Lin Lin Jun-Ming Liu School of Physics &wuhan National High Magnetic Field Center Huazhong University of Science and Technology Laboratory of Solid State Microstructures Nanjing University Institute for Advanced Materials Hubei Normal University

Multiferroics, where multiple ferroic orders coexist and are intimately coupled, promise novel applications in conceptually new devices on one hand, and on the other hand provide fascinating physics that is distinctly different from the physics of high-TCsuperconductors and colossal magnetoresistance manganites. In this mini-review, we highlight the recent progress of single-phase multiferroics in the exploration of new materials, efficient roadmaps for functionality enhancement, new phenomena beyond magnetoelectric coupling, and underlying novel physics. In the meantime, a slightly more detailed description is given of several multiferroics with ferrimagnetic orders and double-layered perovskite structure and also of recently emerging 2 D multiferroics. Some emergent phenomena such as topological vortex domain structure, non-reciprocal response, and hybrid mechanisms for multiferroicity engineering and magnetoelectric coupling in various types of multiferroics will be briefly reviewed.

关键词： multiferroics magnetoelectric coupling non-reciprocity topological domain structure 2D multiferroics

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全身麻醉术后患者睡眠障碍的影响因素分析

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国际精神病学杂志 2024年第3期51卷 913-916页

作者：魏玲郭全周吴梦淏李佩河北省邢台市第三医院麻醉科邢台054000

目的探讨500例全身麻醉手术后患者出现睡眠障碍的影响因素。方法选择2021年1月~2022年12月我院收治的采取全身麻醉进行手术的500例患者,以问卷调查方式对患者睡眠质量进行调查分析,明确其术后出现睡眠障碍发生率,及其发生原因,给予针... 详细信息

目的探讨500例全身麻醉手术后患者出现睡眠障碍的影响因素。方法选择2021年1月~2022年12月我院收治的采取全身麻醉进行手术的500例患者,以问卷调查方式对患者睡眠质量进行调查分析,明确其术后出现睡眠障碍发生率,及其发生原因,给予针对性治疗方案。明确护理前后患者痛觉视觉模拟评分法(visual analogue scale,VAS),焦虑自评量表(Self-Rating Anxiety Scale,SAS)、抑郁自评量表(Self-rating depression scale,SDS)、匹兹堡睡眠质量指数(Pittsburgh sleep quality index,PSQI)评分。结果以术后第7天PSQI评分> 7分为术后睡眠障碍发生标准,500例全身麻醉患者术后睡眠障碍的发生率为29.00%,依照术后睡眠障碍发生情况将患者分为对照组(无全身麻醉术后睡眠障碍,n=355)与研究组(有全身麻醉术后睡眠障碍,n=145),研究组患者患者VAS评分、SAS评分、SDS评分均高于对照组(P<0.05),145例睡眠障碍患者中,占比最高的为疼痛,比例为17.24%;其次为体位不适,占比为15.86%;后续依次为心理问题(13.10%)、呼吸困难(11.03%)、药物因素(9.66%)、护理不到位(7.59%)、并发症(6.69%)。结论疼痛、体位不适、心理问题是导致全身麻醉手术后患者出现睡眠障碍的主要影响因素,临床中给予针对性干预、一对一心理疏导、体位干预以及疼痛干预等可显著改善患者的睡眠质量。

关键词：全身麻醉手术患者睡眠障碍原因

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Rational design of Fe-N-C electrocatalysts for oxygen reduction reaction:From nanoparticles to single atoms

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Nano Research 2022年第3期15卷 1753-1778页

作者： Mengru Sun Changli Chen menghao wu Danni Zhou Zhiyi Sun Jianling Fan Wenxing Chen Yujing Li Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications Experimental Center of Advanced MaterialsSchool of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Department of Physics and Engineering Technology Guilin Normal CollegeGuilin 541199China

As an alternative energy,hydrogen can be converted into electrical energy via direct electrochemical conversion in fuel *** important drawback of full cells is the sluggish oxygen reduction reaction(ORR)promoted by the high-loading of platinum-group-metal(PGM)***-N-C family has been received extensive attention because of its low cost,long service life and high oxygen reduction reaction activity in recent *** order to further enhance the ORR activity,the synthesis method,morphology regulation and catalytic mechanism of the active sites in Fe-N-C catalysts are *** paper reviews the research progress of Fe-N-C from nanoparticles to single *** structure-activity relationship and catalytic mechanism of the catalyst are studied and discussed,which provide a guidance for rational design of the catalyst,so as to promote the more reasonable design of Fe-N-C materials.

关键词： nanoparticle catalyst controlled structure regulation single atomic catalyst local atomic regulation synergistic effect

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腰椎融合术后邻近节段疾病的诊疗现状

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国际外科学杂志 2024年第7期51卷 493-499页

作者：范天奇吴孟昊刘雨泉左维阳杨雍首都医科大学附属北京友谊医院骨科北京100050

邻近节段疾病(ASD)是指腰椎融合术后邻近节段出现椎间盘突出、应力椎体骨折、滑脱、节段侧凸畸形、椎管狭窄和关节突关节退变等退行性病理改变,并随之出现相应的腰骶痛、根性下肢痛或间歇性跛行等临床症状。不同的病理类型ASD的治疗方... 详细信息

邻近节段疾病(ASD)是指腰椎融合术后邻近节段出现椎间盘突出、应力椎体骨折、滑脱、节段侧凸畸形、椎管狭窄和关节突关节退变等退行性病理改变,并随之出现相应的腰骶痛、根性下肢痛或间歇性跛行等临床症状。不同的病理类型ASD的治疗方法各不相同,症状轻者需要保守治疗,而症状严重的患者则需要手术治疗。以往常用后入路或椎间孔入路开放融合手术进行治疗,疗效确切,但存在手术创伤大、术中失血量多和术后恢复慢等弊端。随着近年来微创脊柱手术技术的蓬勃发展,脊柱外科医师积极应用微创手术进行ASD的治疗,有出血量少、住院时间短、恢复快、并发症少等优势,但适应证有所局限。因此,本文通过对不同病理类型的ASD治疗方式进行综述,以期为ASD治疗方式选择提供参考。

关键词：腰椎脊柱融合术诊断治疗结果邻近节段疾病经皮内镜技术

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Ultrahigh-strain ferroelasticity in two-dimensional honeycomb monolayers:from covalent to metallic bonding

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Science Bulletin 2020年第2期65卷 147-152,88页

作者： Zhengyuan Tu menghao wu School of Physics Huazhong University of Science and TechnologyWuhan 430074China

We propose a possible ferroelastic switching pathway of two-dimensional(2 D)honeycomb lattice(including graphene,BN,stanene,etc.)that may swap its armchair and zigzag direction,reversing an unprecedented strain of 73.2%.Our ab initio calculations reveal that such pathway cannot work in covalent systems like graphene and BN;for monolayer with metallic bonds like stanene,stanane and In Bi that have all been synthesized,however,such pathway can be feasible with a low switching barrier(wurtzite structure that can be deemed as multilayer stacking of buckled *** compounds like In Bi monolayer are even multiferroics with both in-plane and vertical ferroelectricity as well as nontrivial topological properties.

关键词： Malleable metallic bonding Ferroelasticity Ultra-high reversible strain Multiferroics Ab initio calculations

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