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Microstructure evolution and improved properties of laminated titanium matrix composites with gradient equiaxed grains

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Science China(Technological Sciences) 2020年第12期63卷 2687-2697页

作者： WANG Shuai HUANG LuJun JIANG Shan ZHANG rui AN Qi SUN Yuan GENG Lin School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China State key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Institute of Metal research Chinese Academy of SciencesShenyang 110016China

With the purpose of improving both the strength and ductility,gradient equiaxed grains were successfully achieved in the matrix of the laminated TiB/Ti-TiB/Ti-6.58Al-1.76Zr-1.04V-0.89Mo composite via water quenching(WQ) and thermal compressing deformation. Gradient equiaxed grains varied from approximately 1.0 μm in TiB/Ti-6.58Al-1.76Zr-1.04V-0.89Mo layer to 5.5 μm in TiB/Ti layer. The formation of the gradient structure was related to the alloying elements diffusion during the initial sintering process,and the equiaxed shape was constructed by dynamic recrystallization during thermal compressing. WQ treatment before thermal compressing was adopted to obtain fine lamellar structure,which promoted the segmentation of αlamellae,and accelerated the dynamic recrystallization process. raising the quenching temperature can increase the proportion of equiaxed grains in the composite,which improved both the bending strength and ductility. Compared with the as-sintered specimen,the specimen with gradient equiaxed grains exhibited nearly 30% enhancement in flexural strength(from 1719 to 2218 MPa),and the ultimate bending fracture strain was increased from 7.0% to 17.2%. This significant improvement should be attributed to the coordination deformation by interface gradient grains,the grain refinement strengthening and the good balance between strength and ductility of the recrystallized equiaxed grains.

关键词： titanium matrix composites laminated structure gradient equiaxed grains microstructure evolution dynamic recrystallization bending properties

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Efficient second harmonic generation by harnessing bound states in the continuum in semi-nonlinear etchless lithium niobate waveguides

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Light(Science & Applications) 2022年第11期11卷 2774-2781页

作者： Xueshi Li Jiantao Ma Shunfa Liu Peinian Huang Bo Chen dunzhao Wei Jin Liu State key Laboratory of Optoelectronic Materials and Technologies School of PhysicsSun Yat-Sen University510275 GuangzhouChina

Integrated photonics provides unprecedented opportunities to pursue advanced nonlinear light sources with lowpower consumptions and small footprints in a scalable manner,such as microcombs,chip-scale optical parametric oscillators and integrated quantum light *** a variety of nonlinear optical processes,high-efficiency second harmonic generation(SHG)on-chip is particularly appealing and yet *** this work,we present efficient SHG in highly engineerable semi-nonlinear waveguides consisting of electron-beam resist waveguides and thin-film silicon nitride(SiN)/lithium niobate(LN).By carefully designing octave-separating bound states in the continuum(BICs)for the nonlinear interacting waves in such a hybrid structure,we have simultaneously optimized the losses for both fundamental frequency(FF)and second harmonic(SH)waves and achieved modal phasing matching and maximized the nonlinear modal overlap between the FF and SH waves,which results in an experimental conversion efficiency up to 4.05%W^(-1)cm^(-2).Our work provides a versatile and fabrication-friendly platform to explore on-chip nonlinear optical processes with high effciency in the context of nanophotonics and quantum optics.

关键词： nonlinear harmonic lithium

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design of Energy Modulation Massive SIMO Transceivers via Machine Learning

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Journal of Communications and Information Networks 2020年第3期5卷 358-368页

作者： Muhang Lan Jianhao Huang Han Zhang Chuan Huang National key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of ChinaChengdu 611731China The Future Network of Intelligence Institute and the School of Science and Engineering the Chinese University of Hong KongShenzhen 518172China department of Electrical and Computer Engineering University of CaliforniaDavis 95616USA

This paper considers a massive single-input multiple-output(SIMO)system,where multiple singleantenna transmitters simultaneously communicate with a receiver equipped with a large number of *** from the conventional noncoherent transceivers which require a certain level of the statistical information on the channel fading,we propose a joint transceiver design method based on machine learning,requiring a limited number of channel *** the proposed method,the multiple transmitters,the channel,and the receiver are represented with a deep neural network(NN),and an autoencoder is adopted to minimize the end-to-end transmission error ***,the relationship between the number of training samples and the transmission error probability is analyzed based on the confidence interval *** results show that the proposed NN-based transceiver achieves lower transmission error probability in typical scenarios,and is more robust against the channel parameters variation compared with the existing methods.

关键词： neural network(NN) energy modulation massive single-input multiple-output(SIMO) joint transceiver design confidence interval

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rapid-Scan and Polarimetric Phased-Array radar Observations of a Tornado in the Pearl river Estuary

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Journal of Tropical Meteorology 2021年第1期27卷 81-86页

作者： ZHANG Yu BAI Lan-qiang MENG Zhi-yong CHEN Bing-hong TIAN Cong-cong FU Pei-ling Guangzhou Meteorological Observatory China Meteorological AdministrationGuangzhou 511430 China School of Atmospheric Sciences/guangdong Province key Laboratory for Climate Change and Natural disaster Studies Sun Yat-sen UniversityZhuhaiGuangdong 519082 China Southern Marine Science and Engineering guangdong Laboratory(Zhuhai) ZhuhaiGuangdong 519082 China department of Atmospheric and Oceanic Sciences School of PhysicsPeking UniversityBeijing 100871 China

The strong destructive winds during tornadoes can greatly threaten human life and destroy *** increasing availability of visual and remote observations,especially by doppler weather radars,is of great value in understanding tornado formation and issuing warnings to the *** this study,we present the first documented tornado over water detected by a state-of-the-art dual-polarization phased-array radar(dual-PAr)in *** contrast to new-generation weather radars,the dual-PAr shows great advantages in tornado detection for its high spatial resolution,reliable polarimetric variables,and rapid-scan *** polarimetric signature of copolar cross-correlation coefficient with anomalously low magnitude appears to be effective for verifying a tornado and thus is helpful for issuing tornado *** guangdong Meteorological Service has been developing an experimental X-band dual-PAr network in the Pearl river delta with the goal of deploying at least 40 advanced dual-PArs and other dual-polarization weather radars before *** network is the first quasi-operational X-band dual-PAr network with unprecedented high coverage in the *** such high-performance close-range PArs,efficient operational nowcasting and warning services for small-scale,rapidly evolving,and damaging weather(e.g.,tornadoes,localized heavy rainfall,microbursts,and hail)can be expected.

关键词： tornado waterspout phased-array radar dual-polarization China

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reshaping plasmon modes by film interference

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Science China(Physics,Mechanics & Astronomy) 2023年第11期66卷 136-144页

作者： Jin Liu Wei Li Junyu Li Jie Zhong He Feng renming Liu Xue-Hua Wang State key Laboratory of Optoelectronic Materials and Technologies School of PhysicsSun Yat-sen UniversityGuangzhou510275China School of Electronics and Information Technology Sun Yat-sen UniversityGuangzhou510006China School of Physics and Electronics Henan UniversityKaifeng475004China

Localized surface plasmon resonances(LSPrs)in metal nanostructures have been a central subject of nano-photonics due to their ability to manipulate light beyond the optical diffraction ***,the large intrinsic dissipations of LSPrs have severely hindered their applications,so the on-demand control of the LSPr modes is highly desired and remains open ***,we experimentally and theoretically demonstrate that the plasmon mode can be effectively engineered by interacting with constructive or destructive modes supported by film *** a metal nanoparticle interacts with a constructive mode,the dissipation linewidth of its LSPr mode shows a significant reduction of 58%.Simultaneously,the scattering intensity is remarkably enhanced,in vast favor of measuring weak signals from small ***,the film-destructiveinterference splitting in the scattering spectrum by weak coupling,rather than strong coupling,is revealed if the plasmon particles interact with the destructive mode,resulting in two new hybrid plasmon modes with narrow *** effective polarizability model of reshaping the LSPr modes by the film interference is present to well understand the experimental *** work may pave the way toward low-loss plasmonic photonics and its practical applications.

关键词： plasmon reshaping dissipation film-destructive-interference splitting film interference

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Bacteroides ovatus-mediated Cd27^(−)MAIT cell activation is associated with obesity-related T2d progression

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Cellular & Molecular Immunology 2022年第7期19卷 791-804页

作者： Yue Li Yi Yang Jin Wang Peihong Cai Mei Li Xixiang Tang Ying Tan Yuchan Wang Fan Zhang Xiaofeng Wen Qiaoxing Liang Yuanpeng Nie Tufeng Chen Xiang Peng Xuemin He Yanhua Zhu Guojun Shi Wai WCheung Lai Wei Yanming Chen Yan Lu department of Endocrinology&Metabolism Guangdong Provincial Key Laboratory of DiabetologyThe Third Affliated Hospital of Sun Yat-sen UniversityGuangzhou 510630China department of Clinical Immunology The Third Affliated Hospital of Sun Yat-sen UniversityGuangzhou 510630China VIP Medical Service Center The Third Affliated Hospital of Sun Yat-sen UniversityGuangzhou 510630China State key Laboratory of Ophthalmology Zhongshan Ophthalmic CenterSun Yat-sen UniversityGuangzhou 510060China department of Gastrointestinal Surgery The Third Affliated Hospital of Sun Yat-sen UniversityGuangzhou 510630China department of rheumatology The Sixth Affliated Hospital of Guangzhou Medical UniversityQingyuan People's HospitalQingyuan 511518China division of Pediatric Nephrology Rady Children's HospitalUniversity of CaliforniaSan DiegoCA 92093-0831USA

Type 2 diabetes(T2d)is highly associated with ***,the factors that drive the transition from excessive weight gain to glucose metabolism disruption are still uncertain and seem to revolve around systemic immune ***-associated invariant T(MAIT)cells,which are innate-like T cells that recognize bacterial metabolites,have been reported to be altered in obese people and to lead to metabolic dysfunction during *** studying the immunophenotypes of blood MAIT cells from a cross-sectional cohort of obese participants with/without T2d,we found an elevation in Cd27^(-)negative(Cd27−)MAIT cells producing a high level of IL-17 under T2d obese conditions,which could be positively correlated with impaired glucose metabolism in obese *** further explored microbial translocation caused by gut barrier dysfunction in obese people as a triggering factor of MAIT cell ***,accumulation of the bacterial strain Bacteroides ovatus in the peripheral blood drove IL-17^(-)producing Cd27−MAIT cell expansion and could be associated with T2d risk in obese ***,these results suggest that an aberrant gut microbiota–immune axis in obese people may drive or exacerbate ***,Cd27−MAIT cell subsets and Bacteroides ovatus could represent targets for novel interventional *** findings extend current knowledge regarding the clinical relevance of body mass index(BMI)-associated variation in circulating MAIT cells to reveal the role of these cells in obesity-related T2d progression and the underlying cellular mechanisms.

关键词： type 2 diabetes obesity MAIT cells Bacteroides ovatus bacterial translocation

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Volatile organic compounds in wintertime North China Plain:Insights from measurements of proton transfer reaction time-of-flight mass spectrometer(PTr-ToF-MS)

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Journal of Environmental Sciences 2022年第4期34卷 98-114页

作者： Xianjun He Bin Yuan Caihong Wu Sihang Wang Chaomin Wang Yibo Huangfu Jipeng Qi Nan Ma Wanyun Xu Ming Wang Wentai Chen Hang Su Yafang Cheng Min Shao Institute for Environmental and Climate research Jinan UniversityGuangzhou 511443China guangdong-Hongkong-Macao Joint Laboratory of Collaborative Innovation for Environmental Quality Guangzhou 511443China State key Laboratory of Severe Weather&key Laboratory for Atmospheric Chemistry of China Meteorology Administration Chinese Academy of Meteorological SciencesBeijing 100081China Collaborative Innovation Center of Atmospheric Environment and Equipment Technology Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution ControlSchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjing 210044China Nanjing Intelligent Environmental Science and Technology Co. Ltd.Nanjing 211800China Max planck Institute for Chemistry Mainz 55128Germany

The characteristics of wintertime volatile organic compounds(VOCs)in the North China Plain(NCP)region are complicated and remain *** measurements were conducted by a proton transfer reaction time-of-flight mass spectrometer(PTr-ToF-MS)at a rural site in the NCP from November to december *** ions measured by PTrToF-MS were quantified and the overall VOC compositions were investigated by combining the measurements of PTr-ToF-MS and gas chromatography-mass spectrometer/flame ionization detector(GC-MS/FId).The measurement showed that although atmospheric VOCs concentrations are often dominated by primary emissions,the secondary formation of oxygenated VOCs(OVOCs)is non-negligible in the wintertime,i.e.,OVOCs accounts for 42%±7%in the total VOCs(151.3±75.6 ppbV).We demonstrated that PTr-MS measurements for isoprene are substantially overestimated due to the interferences of *** chemical changes of organic carbon in a pollution accumulation period were investigated,which suggests an essential role of fragmentation reactions for large,chemically reduced compounds during the heavy-polluted stage in wintertime *** changes of emission ratios of VOCs between winter 2011 and winter 2018 in the NCP support the positive effect of“coal to gas”strategies in curbing air *** high abundances of some key species(*** aromatics)indicate the strong emissions of coal combustion in wintertime of *** ratio of naphthalene to C8 aromatics was proposed as a potential indicator of the influence of coal combustion on VOCs.

关键词： North China Plain Volatile organic compound Wintertime PTr-ToF-MS

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A saw-less direct conversion long term evolution receiver with 25% duty-cycle LO in 130 nm CMOS technology

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Journal of Semiconductors 2013年第3期34卷 70-75页

作者：何思远张常红陶亮张伟锋曾隆月吕伟武海军 Guangzhou runxin Information Technology Co.Ltd School of Electronic and Information Engineering South China University of Technology

A CMOS long-term evolution(LTE) direct convert receiver that eliminates the interstage SAW filter is *** receiver consists of a low noise variable gain transconductance amplifier(TCA),a quadrature passive current commutating mixer with a 25%duty-cycle LO,a trans-impedance amplifier(TIA),a 7th-order Chebyshev filter and programmable gain amplifiers(PGAs).A wide dynamic gain range is allocated in the rF and analog parts.A current commutating passive mixer with a 25%duty-cycle LO improves gain,noise,and linearity. An LPF based on a Tow-Thomas biquad suppresses out-of-band *** in a 0.13μm CMOS process,the receiver chain achieves a 107 dB maximum voltage gain,2.7 dB dSB NF(from PAd port),-11 dBm 11P3,and>+65 dBm UP2 after calibration,96 dB dynamic control range with 1 dB steps,less than 2%error vector magnitude(EVM) from 2.3 to 2.7 *** total receiver(total I Q path) draws 89 mA from a 1.2-V LdO on chip supply.

关键词： rF CMOS passive mixer 25%duty-cycle saw-less noise figure Chebyshev filter LTE

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Atomistic simulation on the generation of defects in Cu/SiC composites during cooling

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Journal of Materials Science & Technology 2022年第28期123卷 1-12页

作者： Yongnan Xiong Wangyu Hu Yao Shu Xing Luo Zhibo Zhang Jiazhen He Cuicui Yin Kaihong Zheng guangdong Academy of Sciences Institute of New MaterialsGuangzhou 510651China guangdong Provincial key Laboratory of Metal Toughening Technology and Application Guangzhou 510561China College of Materials Science and Engineering Hunan UniversityChangsha 410082China

The coefficient of thermal expansion(CTE)mismatch between the reinforcement and the matrix results in thermal residual stresses and defects within metal-matrix composites(MMCs)upon cooling from the processing temperature to ambient *** residual stresses and thermally induced defects play an important role in the mechanical properties of MMCs,it is critical to understand the mechanism of defect formation and *** study provides atomistic simulations to reveal the generation of thermal residual stresses,dislocation and incomplete stacking fault tetrahedron(ISFT)during cooling in the idealized Cu/SiC *** found that dislocations are generated explosively in a certain temperature range during cooling,which results in a non-linear relationship between dislocation density and *** combined effect of the stresses induced by CTE mismatch and the thermodynamic state of the metal leads to the rapid generation of *** Shockley partial and the highly stable stair rod are the two dominant dislocation *** immobile stair-rod dislocations and the highly stable ISFTs formed in the initial high temperature stage inhibit further development of plastic *** present results provide new insights into the defect formation mechanism and the dislocation strengthening mechanism of MMCs caused by thermal mismatch between constituents.

关键词： Metal-matrix composite(MMC) Thermal residual stress dislocation Incomplete stacking fault tetrahedron Molecular dynamics

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Electrodeposited 3d hierarchical NiFe microflowers assembled from nanosheets robust for the selective electrooxidation of furfuryl alcohol

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Green Energy & Environment 2023年第3期8卷 874-882页

作者： Biying Liu Man Zhang Yaoyu Liu Yuchen Wang Kai Yan guangdong Provincial key Laboratory of Environmental Pollution Control and remediation Technology School of Environmental Science and EngineeringSun Yat-sen University135 Xingang Xi RoadGuangzhou510275China

A robust and green strategy for the selective upgrading of biomass-derived platform chemicals towards highly valuable products is important for the sustainable ***,the efficient electrocatalytic oxidation of biomass-derived furfuryl alcohol(FFA)into furoic acid(FurAc)catalyzed by the electrodeposited non-precious NiFe microflowers was successfully reached under the low temperature and ambient *** 3d hierarchical NiFe microflowers assembled from ultrathin nanosheets were controllably synthesized by the electrodeposition method and uniformly grown on carbon fiber paper(CFP).Electrochemical analysis confirmed that NiFe nanosheets more preferred in the selective oxidation of FFA(FFAOr)than oxygen evolution reaction(OEr).The linear sweep voltammetry(LSV)in FFAOr displayed a clear decrease towards lower potential,resulting in 30 mV reduction of overpotential at 20 mA cm^(-2) compared with that of *** optimal catalyst Ni_(1)Fe_(2) nanosheets exhibited the highest selectivity of FurAc(94.0%)and 81.4%conversion of FFA within 3 ***,the influence of various reaction parameters on FFAOr was then explored in *** that,the reaction pathway was investigated and rationally *** outstanding performance for FFAOr can be ascribed to the unique structure of 3d flower-like NiFe nanosheets and oxygen vacancies,resulting in large exposure of active sites,faster electron transfer and enhanced adsorption of *** findings highlight a facile and convenient mean with a promising green future,which is promising for processing of various biomass-derived platform chemicals into value-added products.

关键词： Electrodeposition Microflowers assembled by nanosheets NiOOH Oxygen vacancies Electrochemical oxidation Furfuryl alcohol Furoic acid

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