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Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization Catalysed by Ethylene-Bridged ansa-(3-R-Cyclopentadienyl)(Fluorenyl) Zirconocene Complexes

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Chinese Journal of Polymer Science 2024年第1期42卷 42-51,I0007页

作者： Bo Li Haiyan Ma Jiling huang Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China

A series of C1-symmetric ethylene-bridged ansa-(3-R-cyclopentadienyl)(fluorenyl) metallocene complexes(Zr: 1-5;Hf: 6) have been synthesized, characterized and investigated as catalyst precursors for the high temperature ethylene polymerization. Using methylaluminoxane(MAO) as the cocatalyst, zirconium complexes 1-5 bearing a bulky substituent on the 3-position of the cyclopendienyl ring showed high catalytic activities up to 1.48×10^(7) g PE·mol_(Zr)^(-1)·h^(-1) toward the polymerization of ethylene and afforded polyethylenes with high molecular weights(1.49×10^(5)-6.31×10^(5) g/mol), meanwhile exhibting great thermal stability at high temperatures up to 120 ℃ together with a long catalytic life time up to 2 h. By adopting low Al/Zr ratios, such as 125, polyethylenes with ultra high molecular weights up to 2.86×106 g/mol were obtained. It is worthy of noting that zirconium complexes 1-4 bearing a substituent with an aryl pendant showed temperature-dependent activities, which increased rapidly with the increase of polymerization temperature, thus weak interaction of the pendent aryl group with the cationic active center is proposed to account for the very low activities displayed at low temperatures. In contrast to zirconocene complexes 1-5, hafnocene complex 6 only displayed very low catalytic activities toward the polymerization of ethylene and afforded polyethylenes with molecular weights ten times smaller than those obtained by zirconocene complexes 1-5. Zirconocene complexes 1-5 were also able to catalyse the polymerization of propylene at high temperatures, but only afforded waxes with low molecular weights.

关键词： ansa-Metallocene Ethylene Propylene Polymerization High temperature

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Time-of-flight resolved stimulated Raman scattering microscopy using counter-propagating ultraslow Bessel light bullets generation

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Light(Science & Applications) 2024年第7期13卷 1427-1440页

作者： Shulang Lin Li Gong Zhiwei huang Optical Bioimaging Laboratory Department of Biomedical EngineeringCollege of Design and EngineeringNational University of SingaporeSingapore 117576Singapore

We present a novel time-of-flight resolved Bessel light bullet-enabled stimulated Raman scattering(B2-SRS)microscopy for deeper tissue 3D chemical imaging with high resolution without a need for mechanical *** accomplish the tasks,we conceive a unique method to enable optical sectioning by generating the counterpropagating pump and Stokes Bessel light bullets in the sample,in which the group velocities of the Bessel light bullets are made ultraslow(e.g.,vg≈0.1c)and tunable by introducing programmable angular dispersions with a spatial light *** theoretically analyze the working principle of the collinear multicolor Bessel light bullet generations and velocity controls with the relative time-of-flight resolved detection for SRS 3D deep tissue *** have also built the B2-SRS imaging system and present the first demonstration of B2-SRS microscopy with Bessel light bullets for 3D chemical imaging in a variety of samples(e.g.,polymer bead phantoms,biological samples such as spring onion tissue and porcine brain)with high *** B2-SRS technique provides a>2-fold improvement in imaging depth in porcine brain tissue compared to conventional SRS *** method of optical sectioning in tissue using counter-propagating ultraslow Bessel light bullets developed in B2-SRS is generic and easy to perform and can be readily extended to other nonlinear optical imaging modalities to advance 3D microscopic imaging in biological and biomedical systems and beyond.

关键词： Bessel resolved propagating

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A wide-linear-range and low-hysteresis resistive strain sensor made of double-threaded conductive yarn for human movement detection

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Journal of Materials Science & Technology 2024年第5期172卷 202-212页

作者： Fei huang Jiyong Hu Xiong Yan Shanghai Frontier Science Research Center for Modern Textiles Donghua UniversityShanghai 201620China

Yarn-based flexible strain sensors with advantages in wearability and integrability have attracted wide ***,it is still a big challenge to achieve yarn-based strain sensors with a wide linear strain range,low hysteresis,and durability synchronously that can be used for full range detection of human body ***,a new structure,double-threaded conductive yarn with rhythmic strain distribu-tion,is reported to markedly widen the linear strain range of microcrack-based stretchable strain sensors.A new method of winding and thermally adhering hot-melt filaments on the surface of the elastic fiber is used to achieve double-threaded yarn(DTY)with rhythmic strain *** proposed strategy,the integration of heterogeneous materials,is reported to significantly reduce the mechanical hysteresis of composite *** strain distribution of the DTY during stretching causes multi-level micro-cracks in different regions of the carbon nanotube(CNT)conductive layer deposited on the surface of the ***,the sensing performance of DTY-based strain sensor can be adjusted by designing the structural *** final prepared flexible strain sensor has the advantages of a wide linear strain range(100%),great sensitivity(GF=12.43),low hysteresis,rapid response(158 ms),high repeatability(>2000 cycles at 50%strain),and hydrophobicity,*** sensor can monitor human motion repeatedly and stably well,and shows great advantages in flexible wearable devices.

关键词： Double-threaded yarn Strain redistribution Hysteresis Human motion monitoring

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Scientific and technological innovations of wastewater treatment in China

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Frontiers of Environmental Science & Engineering 2024年第6期18卷 43-48页

作者： Hui huang Rui Ma Hongqiang Ren State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China

The“dual-carbon”strategy promotes the development of the wastewater treatment sector and is an important tool for leading science and technology *** on the global climate change and the new policies introduced by China,this paper described the new needs for the development of wastewater treatment science and *** offered a retrospective analysis of the historical trajectory of scientific and technological advancements in this *** bibliometrics,it delineated the research hotspots within wastewater treatment,notably highlighting materials genomics,artificial intelligence,and synthetic ***,it posited that,in the future,the field of wastewater treatment should follow the paths of technological innovations with multi-dimensional needs,such as carbon reduction,pollution reduction,health,standardisation,and *** purpose of this paper was to provide references and suggestions for scientific and technological innovations in the field of wastewater treatment,and to contribute to the common endeavor of moving toward a Pollution-Free Planet.

关键词： Wastewater treatment Dual-carbon strategy Technological innovation Carbon reduction

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Improvements in properties of NdFeB magnets obtained via magnetron sputtering and thermal diffusion

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Journal of Rare Earths 2024年第9期42卷 1710-1716,I0003页

作者： Jin Tang Weichao huang Dan Li School of Electronic Engineering Guangxi University of Science and TechnologyLiuzhou545006China China Rare Earth(Guangxi)Jinyuan Rare Earth New Materials Co. Ltd.Hezhou542603China China Rare Earth Group Co. Ltd.Ganzhou341000China Center of Experimental Teaching for Common Courses Panzhihua UniversityPanzhihua617000China

The grain boundary diffusion process(GBDP) of Dy and DyAl on sintered NdFeB magnets was conducted via magnetron-sputtering deposition of Dy and DyAl films to enhance coercivity(H_(cj)),The magnetic properties,microstructure and anti-corrosion properties of Dy-surface-alloying NdFeB magnets obtained via magnetron sputtering and thermal diffusion were *** H_(cj) of the Dy_(95)Al_(5)-NdFeB magnet increases by 32.68%,while the remanence declines ***,X-ray diffraction and microstructural analysis confirm the formation of Dy-rich shells,the higher-magnetic-anisotropy field of hard(Nd_(x)Dy_(1-x))2(FeAl)_(14)B magnetic phases and an optimised grain boundary structu re,contributing to the H_(cj)enhancement of the *** elemental distribution and diffusion mechanism of the magnets are also ***,the corrosion resistance of the Dy_(95)Al_(5)-NdFeB magnet is substantially improved by enhancing the electrochemical stability and optimising the distribution and morphology of the intergranular *** findings of this study are of substantial importance in the development of low-heavy rare-earth sintered NdFeB magnets.

关键词： Magnetron sputtering NdFeB Rare earths Microstructure Magnetic property Corrosion resistance

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Morphology of impact fragmentation distribution of single spherical and ellipsoidal particles in drop weight experiments

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Particuology 2024年第3期86卷 137-148页

作者： Qiuhua Miao Peng huang Wenchang Zhu School of Mechanical Engineering Southeast UniversityNanjing211189China

Particle shape is an important factor affecting the fragmentation distribution of the ore *** investigate the influence of particle shape on the morphological fragmentation distribution characteristics,the crushable ore particles are defined as prolate,oblate ellipsoid and spherical particles,which have different aspect ratios(AR)and sphericity(S).Based on the drop weight experiment,the influence of the net drop height on the macroscopic mechanical behavior and crushing distribution characteristics of the single spherical and ellipsoidal particles is *** results show that different peak-shifting characteristics exist during particle *** fragmentation distribution peak shifts left when the increased impact energy is eventually only enough to break medium-sized ***,it shifts right when impact energy is increased enough to break largest-sized ***,regardless of whether the net drop height changes,the maximum continuous fragmentation degree presents"M"-shaped characteristic with the increased *** with the ellipsoid particles,the single spherical particle is more difficult to be broken by impact,with wider equivalent particle fragmentation *** the increase of particle sphericity,the maximum continuous fragmentation degree of a single ellipsoid particle has an overall trend of initial increase and subsequent *** when particle sphericity is 0.9

关键词： Ellipsoid particles Fragmentation distribution Drop weight experiment Numerical simulation

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Research Progress on Bio‑inspired Flapping‑Wing Rotor Micro Aerial Vehicle Development

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Journal of Bionic Engineering 2024年第4期21卷 1621-1643页

作者： Yingjun Pan Shijun Guo Xun huang Centre for Aeronautics School of AerospaceTransport and ManufacturingCranfield UniversityBedford MK430ALUK

Flapping-wing rotor(FWR)is an innovative bio-inspired micro aerial vehicle capable of vertical take-off and *** unique design combines active flapping motion and passive wing rotation around a vertical central shaft to enhance aerodynamic *** research on FWR,though relatively new,has contributed to 6%of core journal publications in the micro aerial vehicle field over the past two *** paper presents the first comprehensive review of FWR,analysing the current state of the art,key advances,challenges,and future research *** review highlights FWR’s distinctive kinematics and aerodynamic superiority compared to traditional flapping wings,fixed wings,and rotary wings,discussing recent breakthroughs in efficient,passive wing pitching and asymmetric stroke amplitude for lift *** experiments and remote-controlled take-off and hovering tests of single and dual-motor FWR models have showcased their *** review compares FWR flight performance with well-developed insect-like flapping-wing micro aerial vehicles as the technology readiness level progresses from laboratory to outdoor flight testing,advancing from the initial flight of a 2.6 g prototype to the current free flight of a 60-gram *** review also presents ongoing research in bionic flexible wing structures,flight stability and control,and transitioning between hovering and cruise flight modes for an FWR,setting the stage for potential applications.

关键词： Flapping-wing rotor Micro aerial vehicle Bio-inspiration Flight

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An efficient approach for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic excitations

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 677-690页

作者： huang Huan Li Yingxiong Li Yuyu College of Water Conservancy and Civil Engineering South China Agricultural UniversityGuangzhou 510642China Institute of Smart City and Intelligent Transportation Southwest Jiaotong UniversityChengdu 611756China

An efficient approach is proposed for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic *** concentrated plastic hinges,described by the Bouc-Wen model,are assumed to occur at the two ends of a linear-elastic beam *** auxiliary differential equations governing the plastic rotational displacements and their corresponding hysteretic displacements are replaced with linearized differential ***,the two sets of equations of motion for the original nonlinear system can be reduced to an expanded-order equivalent linearized equation of motion for equivalent linear *** solve the equation of motion for equivalent linear systems,the nonstationary random vibration analysis is carried out based on the explicit time-domain method with high ***,the proposed treatment method for initial values of equivalent parameters is investigated in conjunction with parallel computing technology,which provides a new way of obtaining the equivalent linear systems at different time *** on the explicit time-domain method,the key responses of interest of the converged equivalent linear system can be calculated through dimension reduction analysis with high *** examples indicate that the proposed approach has high computational efficiency,and shows good applicability to weak nonlinear and medium-intensity nonlinear systems.

关键词： nonstationary random vibration plastic hinge equivalent linearization method explicit time-domain method parallel computation

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Multi-agent reinforcement learning behavioral control for nonlinear second-order systems

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Frontiers of Information Technology & Electronic Engineering 2024年第6期25卷 869-886页

作者： Zhenyi ZHANG Jie huang Congjie PAN College of Electrical Engineering and Automation Fuzhou UniversityFuzhou 350108China G+Industrial Internet Institute Fuzhou UniversityFuzhou 350108China

Reinforcement learning behavioral control(RLBC)is limited to an individual agent without any swarm mission,because it models the behavior priority learning as a Markov decision *** this paper,a novel multi-agent reinforcement learning behavioral control(MARLBC)method is proposed to overcome such limitations by implementing joint ***,a multi-agent reinforcement learning mission supervisor(MARLMS)is designed for a group of nonlinear second-order systems to assign the behavior priorities at the decision *** modeling behavior priority switching as a cooperative Markov game,the MARLMS learns an optimal joint behavior priority to reduce dependence on human intelligence and high-performance computing *** the control layer,a group of second-order reinforcement learning controllers are designed to learn the optimal control policies to track position and velocity signals *** particular,input saturation constraints are strictly implemented via designing a group of adaptive *** simulation results show that the proposed MARLBC has a lower switching frequency and control cost than finite-time and fixed-time behavioral control and RLBC methods.

关键词： Reinforcement learning Behavioral control Second-order systems Mission supervisor

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Lesson Learned from COVID-19 Retrospective Study: An Entropy-Based Clinical-Interpretable Scorecard for Mortality Risk Control at ICU Admission

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Tsinghua Science and Technology 2024年第1期29卷 34-45页

作者： Chong Yao Chonghui huangqi Anpeng huang Laboratory of Network Information Security Beihang UniversityBeijing 100191China Andrew and Erna Viterbi School of Engineering University of Southern CaliforniaLos AnglesCA 90089USA Beijing Goodwill Information and Technology Co. Ltd.and Mobile Health LaboratoryPeking UniversityBeijing 100871China

With severe acute respiratory syndrome coronavirus 2 spreading globally and causing 2019 coronavirus disease(COVID-19),a challenge that we unprepared for was about how to optimally plan and distribute limited top-medical resources for patients in need of urgent *** address this challenge,physicians desperately needed a scientific tool to methodically differentiate between cases with varying *** this study,the unique data of COVID-19 intensive care unit(ICU)patients provided by the national medical team in Wuhan were classified into discrete and continuous variable *** continuous data were discretized using an entropy-based method and transformed into serial information margins,in which each information margin is related to a specific symptom or clinical ***,all these native and processed discrete data were used to configure a readable scorecard through logistic regression,which is the desired scientific tool aforementioned.A total of 322 ICU patients(age:[median:64,interquartile range:54-75],males:178[55.28%],and death:72[22.36%])were included in the *** of mortality in COVID-19 patients can be evaluated using a scorecard model(calibration slope:1.343,Brier:0.048,Dxy=0.972,and population stability index=0.071),with desired model performances(accuracy=0.948,area under curve=0.99,sensitivity=1,and specificity=0.939).This new model can interpret clinical meanings from complex data,and compare it with existing machine learning methods through a black-box *** new data-information model answers a critical question of how a computing algorithm produces clinically meaningful results that will help physicians logically allocate medical resources for COVID-19 ***,this tool has limitations,giving that this research is a retrospective ***,this tool will be tested further and optimized for adaptation to similar clinical cases in the future.

关键词： COVID-19 scorecard clinical-interpretable machine learning ICU admission control

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