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Carbon nanofibers embedded with Fe-Co alloy nanoparticles via electrospinning as lightweight high-performance electromagnetic wave absorbers

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Rare Metals 2024年第6期43卷 2769-2783页

作者： Wen-Jun Cai Jian-Guo Jiang Zi-Dong Zhang Zi-Xuan Liu Lu-Jie Zhang Zhen-Kun Long Ke Bi key laboratory for Liquid-solid Structural Evolution and Processing of Materials (Ministry of Education) Shandong University School of Materials Science and Engineering Shandong University Energy Institute Qilu University of Technology (Shandong Academy of Sciences) state key laboratory of Information Photonics and Optical Communications School of ScienceBeijing University of Posts and Telecommunications

As a lot of electromagnetic pollution and interference issues have emerged,to overcome electromagnetic interference,prevent electromagnetic hazards,and develop new high-performance electromagnetic wave(EMW) absorbers have become a significant task in the field of materials science.In this paper,a three-dimensional(3D) carbon nanofibers network with core-shell structure,embedded with varied molar ratios of iron and cobalt(4:0,3:1,2:2,1:3,0:4),was effectively synthesized(Fe/Co@C-CNFs) via electrospinning.The phase,microstructure,magnetic and EMW absorption properties were studied.It is discovered that Fe/Co@C-CNFs doped with iron:cobalt=1:1 have excellent EMW absorption capacity.When the matching thickness is 1.08 mm,the minimum reflection loss(RL) value is-18.66 dB,while the maximum effective absorption bandwidth(EAB) reaches 4.2 GHz(13.9-18 GHz) at a thickness of 1.22 mm.This is owing to the absorbers' superior impedance matching and multiple reflections as well as the conductivity,dielectric,and magnetic losses of carbon nanofibers embedded with Fe-Co alloy particles.In addition,the radar cross section(RCS) of the absorbers has been calculated by CST Studio Suite,showing that the absorbing coating can effectively reduce the RCS at various angles,especially for Fe/Co@C-CNFs doped with iron:cobalt=1:1.These findings not only provide new insights for the preparation of light-weight and high-performance electromagnetic wave absorbers,but also contribute to energy storage and conversion.

关键词： Electromagnetic wave (EMW) absorbers Fe/Co@C-CNFs Core–shell structure EMW absorbing mechanism Radar cross section (RCS)

Analytical solutions of turbulent boundary layer beneath forward-leaning waves

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 695-710页

作者： Yiqin XIE Jifu ZHOU Xu WANG Jinlong DUAN Yongjun LU Shouqian LI laboratory for Mechanics in Fluid solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China state key laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China state key laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210024China

As a typical nonlinear wave,forward-leaning waves can be frequently encountered in the near-shore areas,which can impact coastal sediment transport significantly.Hence,it is of significance to describe the characteristics of the boundary layer beneath forward-leaning waves accurately,especially for the turbulent boundary layer.In this work,the linearized turbulent boundary layer model with a linear turbulent viscosity coefficient is applied,and the novel expression of the near-bed orbital velocity that has been worked out by the authors for forward-leaning waves of arbitrary forward-leaning degrees is further used to specify the free stream boundary condition of the bottom boundary layer.Then,a variable transformation is found so as to make the equation of the turbulent boundary layer model be solved analytically through a modified Bessel function.Consequently,an explicit analytical solution of the turbulent boundary layer beneath forward-leaning waves is derived by means of variable separation and variable transformation.The analytical solutions of the velocity profile and bottom shear stress of the turbulent boundary layer beneath forward-leaning waves are verified by comparing the present analytical results with typical experimental data available in the previous literature.

关键词： forward-leaning wave turbulent boundary layer velocity profile bottom shear stress

Systematical High-Pressure Study of Praseodymium Nitrides in N-Rich Region

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Chinese Physics Letters 2024年第6期41卷 67-87页

作者：刘冉刘爽张盈王鹏姚震 state key laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China

We investigate high-pressure phase diagrams of Pr–N compounds by proposing five stable structures(PnmaPr N,Ⅰ4/mmm-PrN_(2),C2/m-PrN_(3),P■-PrN_(4),and R3-PrN_(8))and two metastable structures(P■-PrN_(6)and P■-PrN_(10)).The P■-PrN_(6)with the N14-ring layer and R3-PrN_(8)with the N18-ring layer can be quenched to ambient conditions.For the P■-PrN_(10),the N_(22)-ring layer structure transfers into infinite chains with the pressure quenched to ambient pressure.Remarkably,a novel polynitrogen h R8-N designed by the excision of Pr atoms from R3-PrN_(8)is obtained and can be quenched to ambient conditions.The N-rich structures of P■-PrN_(6),R3-PrN_(8),c-PrN_(10)and the solid pure nitrogen structure exhibit outstanding properties of energy density and explosive performance.

关键词： ambient structure layer

Microstructured fluorescence in liquid crystals with femtosecond laser excitation

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Chinese Optics Letters 2024年第3期22卷 154-158页

作者：孟霞金萍葛士军刘娇李炳祥王磊陆延青 College of Electronic and Optical Engineering&College of Flexible Electronics(Future Technology) Nanjing University of Posts and TelecommunicationsNanjing 210023China National laboratory of solid state Microstructures College of Engineering and Applied SciencesNanjing UniversityNanjing 210093China state key laboratory of Millimeter Waves Southeast UniversityNanjing 210096China

This study investigated direct fluorescence generation from a nematic liquid crystal(NLC)NJU-LDn-4 under femtosecond laser excitation.The absorption,transmittance,excitation,and emission spectra of the NLC were assessed.The relationship between the femtosecond pump power and fluorescence intensity was analyzed,revealing a quadratic increase and indicating that two-photon absorption(2PA)is the primary fluorescence mechanism.The LC microstructure was designed using photoalignment technology,allowing the generated fluorescence to reflect the corresponding structure.This research can establish a foundation for tunable LC microstructured fluorescence,with potential applications in fluorescence microscopy and optoelectronics.

关键词： liquid crystal femtosecond laser fluorescence microstructure

Investigation of reflection anisotropy induced by micropipe defects on the surface of a 4H-SiC single crystal using scanning anisotropy microscopy

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Chinese Physics B 2024年第3期33卷 630-637页

作者：黄威俞金玲刘雨彭燕王利军梁平陈堂胜徐现刚刘峰奇陈涌海 key laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049China National key laboratory of solid-state Microwave Devices and Circuits Nanjing Electronic Devices InstituteNanjing 210016China Institute of Micro/Nano Devices and Solar Cells School of Physics and Information EngineeringFuzhou UniversityFuzhou 350108China state key laboratory of Crystal Materials Shandong UniversityJinan 250100China

Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a'butterfly pattern'is obtained around the micropipes by SAM.The RA image of the edge dislocations is theoretically simulated based on dislocation theory and the photoelastic principle.By comparing with the Raman spectrum,it is verified that the micropipes consist of edge dislocations.The different patterns of the RA images are due to the different orientations of the Burgers vectors.Besides,the strain distribution of the micropipes is also deduced.One can identify the dislocation type,the direction of the Burgers vector and the optical anisotropy from the RA image by using SAM.Therefore,SAM is an ideal tool to measure the optical anisotropy induced by the strain field around a defect.

关键词： scanning anisotropy microscopy SiC reflection anisotropy edge dislocation

Enhanced electrochemical performance of nanoscale single crystal NMC811 modification by coating LiNbO_(3)

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Chinese Chemical Letters 2024年第5期35卷 514-518页

作者： Fengyu Zhang Yali Liang Zhangran Ye Lei Deng Yunna Guo Ping Qiu Peng Jia Qiaobao Zhang Liqiang Zhang Clean Nano Energy Center state key laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China School of New Energy and Materials China University of Petroleum BeijingBeijing 102249China Hebei key laboratory of Applied Chemistry College of Environmental and Chemical EngineeringYanshan UniversityQinhuangdao 066004China state key laboratory of Physical Chemistry of solid Surfaces College of MaterialsXiamen UniversityXiamen 361005China

Single crystallization is an important strategy to resolve intergranular cracks and unnecessary side reactions with electrolytes in layered transition metal oxide cathodes LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811).Due to the limitations of high-temperature sintering and multi-step calcination,single crystal NMC811 generally shows irregular particles with a size of 2-3μm.However,the prolonged Li-ion diffusion pathway and the stress generated by the uneven de-/intercalation sluggish Li-ion diffusion kinetics,what is more,cause structural damage such as intragranular cracks.A slow Li extraction rate or particle size reduction will ameliorate the structural damage and improve the cycling stability.As the most promising cathodes for next-generation power batteries,NMC811 required fast charge performance and cycle stability.Particle size reduction appears to be the displacement option.Nanonization is an effective strategy to mitigate intragranular cracks of single crystal NMC811.However,the serious aggregation and increased specific surface area become new challenges.In this article,we synthesized monodisperse nanoscale single crystal NMC811 by molten salt method and modified the surface by LiNbO3 coating.The electrochemical performance shows that nanoscale single crystal NMC811 has faster kinetic and higher capacity retention,so the strategy of combining nanonization and surface coating is an alternative way to prepare high specific capacity and cycle stable single crystal NMC811.

关键词： Ni-rich NMC811 Molten salt method Nanonization Surface coating Micron cracks

Clions accelerating interface charge transfer in a Si/InSFaradaic junction photocathode for solar seawater splitting

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Science China Chemistry 2024年

作者： Jun Luo Ruotong Bao Hongzheng Dong Ye Fu Dongjian Jiang Bo Wang Yuzhan Zheng Qiong Wang Wenjun Luo Zhigang Zou Eco-materials and Renewable Energy Research Center (ERERC) Jiangsu Key Laboratory for Nano Technology National Laboratory of Solid State Microstructures College of Engineering and Applied Sciences Nanjing University National laboratory of solid state Microstructures and Department of Physics Nanjing University

Photoelectrocatalytic seawater splitting is a promising low-cost method to produce green hydrogen in a large scale.The effects of Cl-ions in seawater on the performance of a photoanode have been reported in previous studies.However,few researches have been done on the roles of Cl-ions in a photocathode.Herein,for the first time,we find that Cl-ions in the electrolyte improve the photocurrent of a Si/In2S3photocathode by 50%at-0.6 VRHE.An in-situ X-ray photoelectron spectroscopy （XPS） characterization combined with the time-of-flight secondary-ion mass spectrometry by simulating photoelectrochemical conditions was used to investigate the interface charge transfer mechanism.The results suggest that there is an In+32S3–x（OH）2xlayer on the surface of In2S3in the phosphate buffer solution （PBS） electrolyte,which plays a role as an interface charge transfer mediator in the Si/In2S3photocathode.The In+32S3–x（OH）2xsurface layer becomes In+32S3–x（Cl）2xin the PBS electrolyte with NaCl and accelerates the charge transfer rate at the In2S3/electrolyte interface.These results offer a new concept of regulating interface charge transfer mediator to enhance the performance of photoelectrocatalytic seawater splitting for hydrogen production.

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Generation of orbital angular momentum hologram using a modified U-net

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Chinese Physics B 2024年第3期33卷 401-407页

作者：郑志刚韩菲菲王乐赵生妹 Institute of Signal Processing and Transmission Nanjing University of Posts and TelecommunicationsNanjing 210003China key laboratory of Broadband Wireless Communication and Sensor Network Technology (Ministry of Education) Nanjing University of Posts and TelecommunicationsNanjing 210003China National laboratory of solid state Microstructures Nanjing UniversityNanjing 210093China

Orbital angular momentum(OAM)holography has become a promising technique in information encryption,data storage and opto-electronic computing,owing to the infinite topological charge of one single OAM mode and the orthogonality of different OAM modes.In this paper,we propose a novel OAM hologram generation method based on a densely connected U-net(DCU),where the densely connected convolution blocks(DCB)replace the convolution blocks of the U-net.Importantly,the reconstruction process of the OAM hologram is integrated into DCU as its output layer,so as to eliminate the requirement to prepare training data for the OAM hologram,which is required by conventional neural networks through an iterative algorithm.The experimental and simulation results show that the OAM hologram can rapidly be generated with the well-trained DCU,and the reconstructed image's quality from the generated OAM hologram is significantly improved in comparison with those from the Gerchberg-Saxton generation method,the Gerchberg-Saxton based generation method and the U-net method.In addition,a 10-bit OAM multiplexing hologram scheme is numerically demonstrated to have a high capacity with OAM hologram.

关键词： orbital angular momentum(OAM) holography OAM holography deep learning

A review of low-carbon technologies and projects for the global cement industry

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Journal of Environmental Sciences 2024年第2期136卷 682-697页

作者： Yangyang Guo Lei Luo Tingting Liu Liwei Hao Yinming Li Pengfei Liu Tingyu Zhu CAS key laboratory of Green Process and Engineering Institute of Process EngineeringInnovation Academy for Green ManufactureChinese Academy of SciencesBeijing 100190China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China state key laboratory of solid Waste Reuse for Building Materials Beijing Building Materials Academy of Sciences ResearchBeijing 100041China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou 341000China

Carbon dioxide(CO_(2))emissions from the cement industry account for 26%of the total industrial emissions,and the need to develop low-carbon techniques within the cement industry is extremely urgent.Low-carbon projects and technologies for the cement industry in different regions and countries have been thoroughly reviewed in this manuscript,and the low-carbon development concept for each county has been analyzed.For developing countries such as China and India,energy saving and efficiency enhancement are currently the key points,while for developed countries and regions such as Europe,more efforts have been focused on carbon capture,utilization,and storage(CCUS).Global CCUS projects have been previously conducted,and the majority of CCUS projects are currently performed in Europe where major projects such as the CEMCAP,CLEANKER,and IEILAC projects represent the latest research progress in cement production technologies and low-carbon technologies for the global cement industry.The development of low-carbon cement technologies has changed from focusing on the end point to instead focusing on the source and process through the exploration of hydrogen and solar energies,and more disruptive and original technologies are expected to be developed,particularly in the cement industry in China.

关键词： Cement industry CO_(2)emissions Low carbon development Projects Carbon capture utilization and storage