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Electromagnetic and Microwave Absorption Properties of Fe Coating on SiC with Metal Organic Chemical Vapor Reaction

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Chinese Physics Letters 2014年第4期31卷 167-169页

作者： LIU Yuan LIU Xiang-xuan WANG xuan-Jun wen Wu No. 603 Faculty Xi'an Institute of High Technology Xi'an 710025

SiC-Fe composites are prepared by metal organic chemical vapor deposition （MOCVD） using silicon carbide （SIC＇） and iron pentacarbonyl （Fe（CO）5） as the precursors. The structure and morphology analyses demonstrate that the Fe nanoparticles have been deposited on the surface of the SiC particles. In terms of reflection loss （RL）, the absorbing frequency band （AFB, the value of RL 〈 -10 dB）, and the matching thickness （tin）, SiC-Fe composites show the best performances： minimum RL of - 31.6 dB with tm= 2.0 mm at 15.1 GHz, AFB of 12.9-17.3 OHz, indicating that Fe-doped SiC by MOCVD can significantly improve the electromagnetic properties of SiC and that SiC-Fe composites could be used as an effective microwave absorption materiM.

关键词： Reaction Electromagnetic precursors

Precise Deviations for Discrete Ensembles

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Acta Mathematica Sinica,English Series 2023年第8期39卷 1580-1596页

作者： wen xuan CHEN Fu Qing GAO School of Mathematics and Statistics Wuhan UniversityWuhan 430072P.R.China

We consider precise deviations for discrete ***β=2 case,we first establish an asymptotic formula of the Christoffel–Darboux kernel of the discrete orthogonal polynomials on an infinite regular lattice with weight e^(−NV(x)).Then we use the asymptotic formula to get the precise deviations of the extreme value for corresponding ensemble.

关键词： Discrete ensemble precise deviation random growth model Riemann-Hilbert problem

Contrasting Magnetism in Isovalent Layered LaSr3NiRuO4H4 and LaSrNiRuO4 due to Distinct Spin-Orbital States

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Chinese Physics Letters 2019年第7期36卷 98-102页

作者： xuan wen Ke Yang Hua Wu Laboratory for Computational Physical Sciences (MOE) State Key Laboratory of Surface Physics and Department of Physics Fudan University Shanghai 200433 Collaborative Innovation Center of Advanced Microstructures Nanjing 210093

The recently synthesized first 4d transition-metal oxide-hydride LaSr3NiRuO4H4 with the unusual high H:O ratio surprisingly displays no magnetic order down to 1.8 K. This is in sharp contrast to the similar unusual low-valent Ni^+-Ru^2+ layered oxide LaSrNiRuO4 which has a rather high ferromagnetic(FM) ordering Curie temperature TC^250 K. Using density functional calculations with the aid of crystal field level diagrams and superexchange pictures, we find that the contrasting magnetism is due to the distinct spin-orbital states of the Ru^2+ions(in addition to the common Ni+S = 1/2 state but with a different orbital state): the Ru^2+S = 0 state in LaSr3NiRuO4H4, but the Ru^2+S= 1 state in LaSrNiRuO4. The Ru^2+S = 0 state has the(xy)^2(xz, yz)^4 occupation due to the RuH4O2 octahedral coordination, and then the nonmagnetic Ru2+ions dilute the S= 1/2 Ni^+ sublattice which consequently has a very weak antiferromagnetic superexchange and thus accounts for the presence of no magnetic order down to 1.8 K in LaSr3NiRuO4H4. In strong contrast, the Ru^2+S = 1 state in LaSrNiRuO4 has the(3z^2-r^2)^2(xz, yz)^3(xy)^1 occupation due to the planar square RuO4 coordination, and then the multi-orbital FM superexchange between the S= 1/2 Ni^+ and S= 1 Ru^2+ions gives rise to the high TC in LaSrNiRuO4. This work highlights the importance of spin-orbital states in determining the distinct magnetism.

关键词： The recently synthesized LaSr3NiRuO4H4

Synthesis and Crystal Structure of a Mononuclear Zn(II) Complex with Tridentate Schiff Base,Zn(C_(12)H_(18)N_2O)(NCS)_2

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Chinese Journal of Structural Chemistry 2006年第9期25卷 1031-1034页

作者： CAI wen-xuan wen Yi-Hang SU Hong FENG Yun-Long Institute of Physical Chemistry Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces Zhejiang Normal University Jinhua 321004 China

The title complex Zn（HL）（NCS）2 （C14H18N4OS2Zn, Mr = 387.81, HL = N-（3-dimethyl-aminopropyl）-salicylaldimine） has been synthesized by the reaction of ZnSO4·7H2O with the Schiff base N-（3-dimethylaminopropyl）-salicylaldimine derived from the condensation reaction of 3-dimethylamino- 1-propylamine with salicyladehyde. It crystallizes in the monoclinic system, space group P21/n with a = 9.8360（8）, b = 14.930（1）, c = 12.277（1） A, β= 101.455（2）°, V= 1767.0（3） A 3, Z = 4, F（000） = 800, Dc= 1.458 g/cm^3 and ,μ（MoKα） = 1.631 mm^-1. The structure was refined to R = 0.0463 and wR = 0.1065 for 2681 observed reflections （1 〉 2σ（I））. Crystal analyses revealed that the Zn（Ⅱ） atom is coordinated by two nitrogen atoms of two NCS^-, and an oxygen atom as well as a nitrogen atom of amine from the neutral Schiff base ligand of N-（3-dimethyl-aminopropyl）-salicylaldimine to give a distorted tetrahedral geometry.

关键词： 3-dimethylamino-1-propylamine salieylaldehyde Sehiff base,

Catalytic effect in lithium metal batteries: From heterogeneous catalyst to homogenous catalyst

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Journal of Energy Chemistry 2024年第3期90卷 305-326,I0008页

作者： Haining Fan xuan-wen Gao Hailong Xu Yichun Ding Shi-Xue Dou wen-Bin Luo School of Fashion and Textiles The Hong Kong Polytechnic UniversityHong Kong 100872China Institute for Energy Electrochemistry and Urban Mines Metallurgy School of MetallurgyNortheastern UniversityShenyang 110819LiaoningChina Institute of Energy Materials Science University of Shanghai for Science and TechnologyShanghai 200000China State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710000ShaanxiChina

Lithium metal batteries are regarded as prominent contenders to address the pressing needs owing to the high theoretical *** the broader implementation,the primary obstacle lies in the intricate multi-electron,multi-step redox reaction associated with sluggish conversion kinetics,subsequently giving rise to a cascade of parasitic *** order to smooth reaction kinetics,catalysts are widely introduced to accelerate reaction rate via modulating the energy *** past decades,a large amount of research has been devoted to the catalyst design and catalytic mechanism exploration,and thus the great progress in electrochemical performance has been ***,it is necessary to make a comprehensive review toward key progress in catalyst design and future development *** this review,the basic mechanism of lithium metal batteries is provided along with corresponding advantages and existing challenges detailly *** main catalysts employed to accelerate cathode reaction with emphasis on their catalytic mechanism are summarized as ***,the rational design and innovative direction toward efficient catalysts are suggested for future application in metal-sulfur/gas battery and *** review is expected to drive and benefit future research on rational catalyst design with multi-parameter synergistic impacts on the activity and stability of next-generation metal battery,thus opening new avenue for sustainable solution to climate change,energy and environmental issues,and the potential industrial economy.

关键词： Energy storage and conversion Metal battery Sulfur battery Air battery Catalytic effect Heterogeneous catalyst Homogeneous catalyst

Spectral and Energy Efficiency of Line-of-Sight OAM-MIMO Communication Systems

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China Communications 2020年第9期17卷 119-127页

作者： Rui Chen Hong Zhou wen-xuan Long Marco Moretti State Key Laboratory of ISN Xidian UniversityXi'an 710071China University of Pisa Dipartimento di Ingegneria dell’InformazioneItaly

Not only high spectral efficiency(SE)but also high energy efficiency(EE)are required for future wireless communication *** orbital angular momentum(OAM)provides a new perspective of mode multiplexing to improve ***,there are few studies on the EE performance of OAM mode *** this paper,we investigate the SE and EE of a misaligned uniform concentric circle array(UCCA)-based multi-carrier multimode OAM and multiple-input multiple-output(MCMM-OAM-MIMO)system in the line-ofsight(LoS)channel,in which two transceiver architectures implemented by radio frequency(RF)analog synthesis and baseband digital synthesis are *** distance and angle of arrival(AoA)estimation are utilized for channel estimation and signal detection,whose training overhead is much less than that of traditional MIMO *** results validate that the UCCA-based MCMM-OAM-MIMO system is superior to conventional MIMOOFDM system in the EE and SE performances.

关键词： orbital angular momentum(OAM) uniform concentric circle array(UCCA) spectral efficiency(SE) energy efficiency(EE)

Boosting nitrogen electrocatalytic fixation by three-dimensional TiO_(2-δ)N_δnanowire arrays

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Journal of Energy Chemistry 2022年第12期75卷 293-300,I0008页

作者： Jianjia Mu xuan-wen Gao Zhaomeng Liu wen-Bin Luo Zhenhua Sun Qinfen Gu Feng Li School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina Institute of Metal Research Chinese Academy of SciencesShenyang 110016LiaoningChina Australian Synchrotron(ANSTO) 800 Blackburn RdClayton 3168VictoriaAustralia

Owing to the environmental and inherent advantages,nitrogen reduction reaction(NRR)by electrocatalysts attracts global *** surface engineering is widely employed to enhance the electrocatalytic activity by atomic defects and heterostructure effects.A three-dimensional(3D)free-standing integrated electrode was fabricated by numerous nearly-single-crystal TiO_(2-δ)N_δnanowire *** on the high electronic conductivity network,it exposes numerous active sites as well to facilitate the selective nitrogen adsorption and*H adsorption *** synergistic effects between Ti^(3+)and oxygen vacancy(O_v)boost the intrinsic catalytic activity,in which Ti^(3+)acquired electrons via Ovcan effectively activate the N≡N bond and make it easy to bind with *** energy barrier of primary protonation process(*N_(2)+H^(+)+e^(-)→*NNH)can be dramatically *** highest ammonia yield rate(14.33μg h^(-1)mgcat^(-1))emerges at-0.2 V,while the optimal ammonia Faradaic efficiency(9.17%)is acquired at-0.1 *** functional theory(DFT)calculation reveals that the Ti^(3+)can be served as the active sites for nitrogen adsorption and activation,while ammonia synthesis is accomplished by the distal *** high electronic conductivity integrated network and synergistic effects can significantly facilitate nitrogen absorption and accelerate electrocatalytic reaction kinetic,which are responsible for the excellent NRR performance at room temperature.

关键词： Nanowires TiO_(2-δ)N_δ Electrocatalysis NRR DFT

Variations in aeolian landform patterns in the Gonghe Basin over the last 30 years

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Journal of Mountain Science 2021年第8期18卷 2034-2047页

作者： QI Yu-han PAN Mei-hui HAO Ze-wen YANG An-na XUE wen-xuan College of Geography and Environment Science Northwest Normal UniversityLanzhou730070China

Wind erosion,or the transportation and deposition of sand into desert dunes and aeolian loess,is one of the most important aeolian *** progression of aeolian landforms expands arid and barren landscapes,leading to the degradation of adjacent *** Gonghe Basin,as a typical plateau with abundant sand sources,is highly sensitive to changes in the local climate *** order to quantify the spatial-temporal variations in the aeolian landforms in the Gonghe Basin,we conducted field surveys and also analyzed twelve remote sensing(Landsat5 TM and Landsat8 OLI)images that sample the Gonghe Basin from 1989 to *** the Gonghe Basin,we identified aeolian landforms such as climbing dunes on the windward slopes of the foothills,checkerboard dunes in the southeastern part of the basin,flat dunes,parabolic dunes and crescent dunes on the east and west sides of Longyangxia Reservoir,shrubby sandbanks on the valley slope in Shazhuyu,Tanggemu,and Indel,and sandy thickets at the bottom of the valley near the Dalian Sea,the Longyangxia Reservoir,and the tributaries of the Yellow *** 1989 to 2005,the area of the aeolian regions expanded by 816.7 km2,with an annual conversion rate of 0.05%.From 2015 to 2019,the area of the aeolian regions shrunk by 2411.9 km2,with an annual conversion rate of−0.15%.The number and size of the fixed and semi-fixed dunes(*** shrubby sandbanks on the valley slope and the sandy thickets at the bottom of the valley)were more stable than those of the mobile dunes(*** checkerboard dunes,the flat dunes,the crescent dunes,the parabolic dunes,and the climbing dunes).The fixed and semi-fixed dunes were arranged in an irregular ring shape,and the location of the center of gravity of this ring did not change significantly from 1989 to 2019;in this time,the mobile dunes migrated to the northwest.

关键词： Gonghe Basin Spatial-temporal variation Aeolian processes Remote sensing interpretation

Genetic diversity and temporal changes of an endemic cyprinid fish species, Ancherythroculter nigrocauda,from the upper reaches of Yangtze River

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Zoological Research 2019年第5期40卷 427-438页

作者： Dong-Dong Zhai wen-Jing Li Huan-Zhang Liu wen-xuan Cao Xin Gao Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences Institute of Hydrobiology Chinese Academy of Sciences Wuhan Hubei 430072 China University of Chinese Academy of Sciences Beijing 100049 China

Small populations with low genetic diversity are prone to extinction. Knowledge on the genetic diversity and structure of small populations and their genetic response to anthropogenic effects are of critical importance for conservation management. In this study, samples of Ancherythroculter nigrocauda, an endemic cyprinid fish from the upper reaches of Yangtze River, were collected from five sites to analyze their genetic diversity and population structure using mitochondrial cytochrome b gene and 14 microsatellite loci. Haplotype diversity, nucleotide diversity, and expected heterozygosity indicated that the A. nigrocauda populations had low genetic diversity, and decreased heavily from 2001 to 2016. Significant genetic differentiation was found among different populations in the cyt b gene and SSR markers based on the genetic differentiation index (F ST), whereas no differentiation was found in 2001. Haplotype genealogy showed that eight out of 15 haplotypes were private to one population. The SSR STRUCTURE analysis showed that there were four genetic clusters in the A. nigrocauda samples, with each population forming a single cluster, except for the Chishui River (CSR) and Mudong River (MDR) populations, which formed a common cluster. Therefore, loss of genetic diversity and increased genetic differentiation were found in the A. nigrocauda populations, which could be attributed to dam construction, overfishing, and water pollution in the upper Yangtze River. It is therefore recommended that the government should ban fishing, control water pollution, increase river connectivity, and establish artificial breeding and stocking.

关键词： Genetic diversity Population structure Temporal change Conservation