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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

Effect of two-step solid solution on microstructure andδphase precipitation of Inconel 718 alloy

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2199-2207页

作者： Enyu liu Qingshuang Ma Xintong li Aoxue gao jing Bai liming Yu Qiuzhi gao Huijun li School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao 066004China School of Materials Science&Engineering Tianjin UniversityTianjin 300354China School of Mechanical Materials and Mechatronic EngineeringUniversity of WollongongWollongongNSW 2522Australia

Inconel 718 is the most popular nickel-based superalloy and is extensively used in aerospace,automotive,and energy indus-tries owing to its extraordinary thermomechanical *** effects of different two-step solid solution treatments on microstructure andδphase precipitation of Inconel 718 alloy were studied,and the transformation mechanism fromγ″metastable phase toδphase was *** precipitates were statistically analyzed by X-ray *** results show that theδphase content firstly increased,and then decreased with the temperature of the second-step solid *** changes in microstructure andδphase were studied by scanning electron microscopy and transmission electron *** intragranularδphase formed in Inconel 718 alloy at the second-[100]_(δ)[011]γ step solid solution temperature of 925℃,and its orientation relationship withγmatrix was determined as//and(010)_(δ)//(111)γ.Furthermore,the Vickers hardness of different heat treatment samples was measured,and the sample treated by second-step solid solution at 1010℃ reached the maximum hardness of HV 446.84.

关键词： Inconel 718 alloy two-step solid solution treatment δphase γ″-δtransformation

S-scheme heterojunction in photocatalytic hydrogen production

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Journal of Materials Science & Technology 2024年第2期169卷 82-104页

作者： Teng li Noritatsu Tsubaki Zhiliang jin School of Chemistry and Chemical Engineering North Minzu UniversityYinchuan 750021China Department of Applied Chemistry Graduate School of EngineeringUniversity of ToyamaGofuku 3190Toyama 930-8555Japan

As an ideal secondary energy source,hydrogen has the title of clean energy and the product of its complete combustion is only water,which is not polluting to the *** hydrogen production technology is an environmentally friendly,safe,and low-cost strategy that requires only an inexhaustible amount of solar energy and water as *** paper provides a detailed and detailed review of S-scheme heterojunction photocatalysts for photocatalytic hydrogen production,mainly including TiO_(2)-based,Perovskite-based,CdS-based,Graphitic phase carbon nitride-based,COF-based graphdiyne-based,ZnO-based,and ZnIn_(2)S_(4)-based S-scheme heterojunction *** classification of S-scheme heterojunctions is ***’s more,various characterizations for direct verification of the charge migration mechanism of S-scheme heterojunctions are *** on the present study,the future potential challenges and future research trends for S-scheme heterojunctions in photocatalytic hydrogen evolution technology are pointed out,which provides feasible strategies for the development and design of S-scheme heterojunction photocatalysts in the field of photocatalytic hydrogen evolution.

关键词： S-scheme heterojunction Photocatalysis Charges migration Hydrogen evolution

Multi-Objective Multi-Variable Large-Size Fan Aerodynamic Optimization by Using Multi-Model Ensemble Optimization Algorithm

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Journal of Thermal Science 2024年第3期33卷 914-930页

作者： XIONG jin GUO Penghua li jingyin School of Energy and Power Engineering Xi’an Jiaotong UniversityXi’an710049China

The constrained multi-objective multi-variable optimization of fans usually needs a great deal of computational fluid dynamics(CFD)calculations and is *** this study,a new multi-model ensemble optimization algorithm is proposed to tackle such an expensive optimization *** multi-variable and multi-objective optimization are conducted with a new flexible multi-objective infill *** addition,the search direction is determined by the multi-model ensemble assisted evolutionary algorithm and the feature extraction by the principal component analysis is used to reduce the dimension of optimization ***,the proposed algorithm and other two optimization algorithms which prevail in fan optimizations were compared by using test *** the same number of objective function evaluations,the proposed algorithm shows a fast convergency rate on finding the optimal objective function ***,this algorithm was used to optimize the rotor and stator blades of a large axial fan,with the efficiencies as the objectives at three flow rates,the high,the design and the low flow ***-two variables were included in the optimization *** results show that compared with the prototype fan,the total pressure efficiencies of the optimized fan at the high,the design and the low flow rate were increased by 3.35%,3.07%and 2.89%,respectively,after CFD simulations for 500 fan candidates with the constraint for the design *** optimization results validate the effectiveness and feasibility of the proposed algorithm.

关键词： multi-objective optimization surrogate-assisted evolutionary algorithm axial fan computational fluid dynamics aerodynamic optimization

Spatiotemporal pattern of climate change in the China-Myanmar Economic Corridor from 1901 to 2018

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Journal of Mountain Science 2024年第1期21卷 131-145页

作者： YANG Xiaoliu li Yungang gao Lu Institute of Geography Fujian Normal UniversityFuzhou 350117China School of Geographical Sciences Fujian Normal UniversityFuzhou 350117China Institute of International Rivers and Eco-Security Yunnan UniversityKunming 650500China Fujian Provincial Engineering Research Center for Monitoring and Accessing Terrestrial Disasters Fujian Normal UniversityFuzhou 350117China Key Laboratory for Humid Subtropical Eco-geographical Processes of the Ministry of Education Fujian Normal UniversityFuzhou 350117China

The China-Myanmar Economic Corridor(CMEC) is an important part of China's Belt and Road Initiative and an important area for global ecology and biodiversity. In this study, the annual and seasonal spatiotemporal patterns of temperature and precipitation in the CMEC over the past century were investigated using linear tendency estimation, the Mann-Kendall mutation test, the T-test, and wavelet analysis based on the monthly mean climatic data from 1901 to 2018 released by the Climatic Research Unit(CRU) of the University of East Anglia, UK. The results show that the CMEC demonstrated a trend of warming and drying over the past 100 years, and the rate of change in Myanmar was stronger than that in Yunnan Province of China. The warming rate was 0.039 ℃/10a. Precipitation decreased at a rate of -6.1 mm/10a. From the perspective of spatial distribution, temperature was high in the central and southern, low in the north of the CMEC, and the high-temperature centers were mainly distributed in the southern plain and river valley. Precipitation decreased from west to east and from south to north of the CMEC. From the perspective of the rate of change, warming was stronger in central and northern CMEC than in southern and northeastern CMEC. The rate of precipitation decline was stronger in the central and western regions than in the eastern region. This study provides a scientific reference for the CMEC to address climate change and ensure sustainable social and economic development and ecological security.

关键词： China-Myanmar Economic Corridor CRU Air temperature Precipitation Spatiotemporal pattern

A weak but inert hindered urethane bond for high-performance dynamic polyurethane polymers

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Chinese Chemical Letters 2024年第5期35卷 238-243页

作者： Fangzhou Wang Wentong gao Chenghui li State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210023China School of Materials Science and Engineering Nanjing Institute of TechnologyNanjing 211167China

Covalent adaptable networks(CANs),which share the properties of both thermosets and thermoplastics at the same time,are desirable for many *** bulky substituents is a feasible way to design dynamic covalent bonds for constructing CANs,as evidenced by the successful implementation in CANs based on hindered urea bonds(HUBs).However,the dynamicity induced by introducing bulky substituents always come with low bond energy,resulting in low mechanical strength and poor stability of the ***,we designed a novel hindered urethane bond,which is weak in thermodynamic(K_(eq)=1701.23 L/mol at 25℃)and inert in kinetic at low temperature,but stable in thermodynamic(K_(eq)=1.54×10^(4) L/mol at 100℃)and active in kinetic at high temperature(k_(-1)=0.105 h^(-1) at 80℃ and 0.315 h^(-1) at 120℃).As a result,the polyurethane based on it exhibits high mechanical properties(with Youngs’modulus of 1011±29MPa and flexible modulus reached 1833±50MPa)and excellent reversibility(can be reprocessed at 60℃ under 100 kPa in 30 min and completely healed at 40℃ in 10 min).Moreover,unlike to many CANs based on hindered urea bonds,our dynamic polyurethanes are highly stable in humid environment or even water solutions due to the slow hydrolysis *** highperformance dynamic polyurethane polymers are attractive for many applications.

关键词： Covalent adaptable networks Urethane bond Kinetics Thermodynamics

Predict the evolution of mechanical property of Al-li alloys in a marine environment

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Defence Technology（防务技术） 2024年第1期31卷 557-566页

作者： Wei li lin Xiang Guang Wu Hongli Si jinyan Chen Yiming jin Yan Su Jianquan Tao Chunyang Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100036China Chongqing Innovation Center Beijing Institute of TechnologyChongqing400044China First Research Institute of the Ministry of Public Security for PR China Beijing100036China Southwest Technology and Engineering Research Institute Chongqing400039China

The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and *** study it is to develop a Machine learning(ML)-based prediction method to study the evolution of the mechanical properties of Al-li alloys in the marine *** obtained the mechanical properties of Al-li alloy samples under uniaxial tensile deformation at different exposure times through Marine exposure *** obtained the strain evolution by digital image correlation(DIC).The strain field images are voxelized using 2D-Convolutional Neural Networks(CNN)autoencoders as input data for Long Short-Term Memory(LSTM)neural ***,the output data of LSTM neural networks combined with corrosion features were input into the Back Propagation(BP)neural network to predict the mechanical properties of Al-li *** main conclusions are as follows:*** variation law of mechanical properties of2297-T8 in the Marine atmosphere is *** the increase in outdoor exposure test time,the tensile elastic model of 2297-T8 changes slowly,within 10%,and the tensile yield stress changes significantly,with a maximum attenuation of 23.6%.*** prediction model can predict the strain evolution and mechanical response simultaneously with an error of less than 5%.*** study shows that a CNN/LSTM system based on machine learning can be built to capture the corrosion characteristics of Marine exposure *** results show that the relationship between corrosion characteristics and mechanical response can be predicted without considering the microstructure evolution of metal materials.

关键词： Marine environment Al-li alloy Machine learning Corrosion

Differentiation and immunosuppressive function of CD19^(+)CD24^(hi)CD27^(+) regulatory B cells are regulated through the miR-29a-3p/NFAT5 pathway

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Hepatobiliary & Pancreatic Diseases International 2024年第5期23卷 472-480页

作者： jin-Yang li Tian-Shuo Feng Ji gao Xin-Xiang Yang Xiang-Cheng li Zhen-Hua Deng Yong-Xiang Xia Zheng-Shan Wu Hepatobiliary Center the First Affiliated Hospital of Nanjing Medical UniversityNanjing 210029China Key Laboratory of liver Transplantation Chinese Academy of Medical SciencesNanjing 210029China NHC Key Laboratory of living Donor liver Transplantation Nanjing Medical UniversityNanjing 210029China

Background: Regulatory B cells(Bregs) is an indispensable element in inducing immune tolerance after liver transplantation. As one of the microRNAs(miRNAs), mi R-29a-3p also inhibits translation by degrading the target mRNA, and yet the relationship between Bregs and mi R-29a-3p has not yet been fully explored. This study aimed to investigate the impact of miR-29a-3p on the regulation of differentiation and immunosuppressive functions of memory Bregs(m Bregs) and ultimately provide potentially effective therapies in inducing immune tolerance after liver transplantation. Methods: Flow cytometry was employed to determine the levels of Bregs in peripheral blood mononuclear cells. TaqMan low-density array miRNA assays were used to identify the expression of different miRNAs, electroporation transfection was used to induce mi R-29a-3p overexpression and knockdown, and dual luciferase reporter assay was used to verify the target gene of miR-29a-3p. Results: In patients experiencing acute rejection after liver transplantation, the proportions and immunosuppressive function of m Bregs in the circulating blood were significantly impaired. mi R-29a-3p was found to be a regulator of m Bregs differentiation. Inhibition of miR-29a-3p, which targeted nuclear factor of activated T cells 5(NFAT5), resulted in a conspicuous boost in the differentiation and immunosuppressive function of m Bregs. The inhibition of mi R-29a-3p in CD19~+ B cells was capable of raising the expression levels of NFAT5, thereby promoting B cells to differentiate into m Bregs. In addition, the observed enhancement of differentiation and immunosuppressive function of m Bregs upon mi R-29a-3p inhibition was abolished by the knockdown of NFAT5 in B cells. Conclusions: mi R-29a-3p was found to be a crucial regulator for m Bregs differentiation and immunosuppressive function. Silencing mi R-29a-3p could be a potentially effective therapeutic strategy for inducing immune tolerance after liver transplantation.

关键词： Regulatory B cells miR-29a-3p NFAT5 liver transplantation

Vibration transfer from underground train to multi-story building:Modelling and validation with in-situ test data

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Underground Space 2024年第6期19卷 301-316页

作者： li Wang Xin gao Caiyou Zhao Ping Wang Zili li Section of Railway Engineering Delft University of TechnologyStevinweg 12628CN DelftThe Netherlands Key Laboratory of High-speed Railway Engineering(Southwest Jiaotong University) Ministry of EducationChengdu 610031China

Excessive underground train-induced vibration becomes a serious environmental problem in *** investigate the vibration transfer from an underground train to a building nearby,an explicit-integration time-domain,three-dimensional finite element model is *** underground train,track,tunnel,soil layers and a typical multi-story building nearby are all fully coupled in this *** complex geometries involving the track components and the building are all modelled in detail,which makes the simulation of vibration transfer more realistic from the underground train to the *** model is validated with in-situ tests data and good agreements have been achieved between the numerical results and the experimental results both in time domain and frequency *** proposed model is applied to investigate the vibration transfer along the floors in the building and the influences of the soil stiffness on the vibration characteristics of the track-tunnel-soil-building *** is found that the building vibration induced by an underground train is dominant at the frequency determined by the P2 resonance and influenced by the vibration modes of the *** vertical vibration in the building decreases in a fluctuant pattern from the foundation to the top floor due to loss of high frequency contents and local *** vibration levels in different rooms at a same floor can be different due to the different local stiffness.A room with larger space thus smaller local stiffness usually has higher vibration *** soil layers make the tunnel lining and the building have more low frequency *** influence of the soil stiffness on the amplification scale along the floors of the building is found to be nonlinear and frequency-dependent,which needs to be further investigated.

关键词： Railway vibration Underground train Multi-story building vibration Finite element model Dynamic interaction