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Precipitation and decomposition behaviors of carbides in AISI M2 high-speed steel with nitrogen and mischmetal

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Journal of Central South University 2017年第4期24卷 782-788页

作者： LIU Bao-long Lü zhi-qing FENG Wei-wei ren ting-zhi FU Wan-tang College of Mechanical Engineering Yanshan University China First Heavy Industries State Key Laboratory of Metastable Material Science and Technology Yanshan University

The behaviors of the precipitation and decomposition of carbides in AISI M2 high-speed steel modified by nitrogen and mischmetal were investigated using DSC, XRD, SEM and TEM. The as-cast microstructure of the experimental steel consists of dendrites of iron matrix, networks of eutectic carbides and secondary carbides. The average distance between networks is about 34 μm. The carbides mainly include M_2C, M(C,N) and M_6C, and their relative contents are 58.5%, 30.3% and 11.2%, respectively. The average spacing between the M_2C fibers is 1.5 μm. The decomposition of M_2C occurs from 897.2 to 1221.5 ℃(heating rate of 200 ℃/h). Some precipitated carbide particles occur in the M_2C matrix after holding for 15 min at 1100 ℃. With increasing holding time, the carbide fibers neck down more and more obviously until they are broken down. The spectral peaks of M_2C almost disappear after holding for 60 min. The spectral peaks of M_6C gradually strengthen with the holding time, and the relative content of M_6C increases to 79.8% after holding for 60 min. After holding for 180 min, the carbide fibers disappear, and the decomposition products consist of fine carbide particles(about 300 nm) and short rod-like carbides(about 3.5 μm).

关键词： high-speed steel metastable carbides decomposition phase transformation refinement

Isotopic dependence of the yield ratios of light fragments from different projectiles and their unified neutron skin thicknesses

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Nuclear Science and Techniques 2024年第3期35卷 228-236页

作者： ting-zhi Yan Shan Li School of Energy and Power Engineering Northeast Electric Power UniversityJilin 132012China

The yield ratios of neutron-proton(R(n/p))and^(3)H-^(3)He(R(^(3)H∕^(3)He))with reduced rapidity from 0 to 0.5 were simulated at 50 MeV/u even-even ^(36−56)Ca+^(40)Ca,even-even ^(48−78)Ni+^(58)Ni,and ^(100−139)Sn(every third isotopes)+112 Sn for full reduced impact parameters using the isospin-dependent quantum molecular dynamics(IQMD)*** neutron and proton density distributions and root-mean-square radii of the reaction systems were obtained using the Skyrme-Hartree-Fock model,which was used for the phase space initialization of the projectile and target in *** defined the unified neutron skin thickness asΔRnp=^(1∕2) n−^(1∕2)p,which was negative for neutron-deficient *** unifiedΔRnp values for nuclei with the same relative neutron excess from different isotopic chains were nearly equal,except for extreme neutron-rich isotopes,which is a type of scaling *** yield ratios of the three isotopic chain-induced reactions,which depended on the reduced impact parameter and unified neutron skin thickness,were *** results showed that both R(n/p)and R(^(3)H∕^(3)He)decreased with a reduced impact parameter for extreme neutron-deficient isotopes;however,they increased with reduced impact parameters for extreme neutron-rich isotopes,and increased with theΔRnp of the projectiles for all reduced impact *** addition,a scaling phenomenon was observed betweenΔR np and the yield ratios in peripheral colli-sions from different isotopic chain projectiles(except for extreme neutron-rich isotopes).Thus,R(n/p)and R(^(3)H∕^(3)He)from peripheral collisions were suggested as experimental probes for extracting the neutron or proton skin thicknesses of non-extreme neutron-rich nuclei from different isotopic chains.

关键词： Exotic nuclei Unified neutron skin thickness Yield ratios IQMD

Snap-through behaviors and nonlinear vibrations of a bistable composite laminated cantilever shell:an experimental and numerical study

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 779-794页

作者： Lele ren Wei ZHANG ting DONG Yufei ZHANG State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Department of Mechanics Guangxi UniversityNanning 530004China Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Structures College of Mechanical EngineeringBeijing University of TechnologyBeijing 100124China School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

The snap-through behaviors and nonlinear vibrations are investigated for a bistable composite laminated cantilever shell subjected to transversal foundation excitation based on experimental and theoretical *** improved experimental specimen is designed in order to satisfy the cantilever support boundary condition,which is composed of an asymmetric region and a symmetric *** symmetric region of the experimental specimen is entirely clamped,which is rigidly connected to an electromagnetic shaker,while the asymmetric region remains free of *** motion paths are realized for the bistable cantilever shell by changing the input signal levels of the electromagnetic shaker,and the displacement responses of the shell are collected by the laser displacement *** numerical simulation is conducted based on the established theoretical model of the bistable composite laminated cantilever shell,and an off-axis three-dimensional dynamic snap-through domain is *** numerical solutions are in good agreement with the experimental *** nonlinear stiffness characteristics,dynamic snap-through domain,and chaos and bifurcation behaviors of the shell are quantitatively *** to the asymmetry of the boundary condition and the shell,the upper stable-state of the shell exhibits an obvious soft spring stiffness characteristic,and the lower stable-state shows a linear stiffness characteristic of the shell.

关键词： bistable composite laminated cantilever shell snap-through behavior nonlinear vibration nonlinear stiffness characteristic chaos and bifurcation

Normalized Solution for p-Kirchhoff Equation with a L2-supercritical Growth

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Acta Mathematicae Applicatae Sinica 2024年第2期40卷 414-429页

作者： zhi-min ren Yong-yi LAN School of Sciences Jimei UniversityXiamen 361005China

In this paper,we investigate the following p-Kirchhoff equation{∫R^(N)|u|^(2)dx=ρ,(a+b)∫RN(|Δu}^(p)+|u|^(p))dx)(-Δpu+|u|^(p-2u)=|u|^(s-2)u+μu,x∈R^(N),where a>0,b≥0,p>0 are constants,constants,p*=N-P/Np is the ... 详细信息

关键词： p-Kirchhoff equation normalized solution mountain-pass lemma

Recent advances in Fe-N-C-and Co-N-C-based materials as bifunctional electrocatalysts for oxygen reduction and oxygen evolution

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Science China Chemistry 2024年第4期67卷 1137-1160页

作者： Hui-Min Xu Hong-Rui Zhu Chen-Jin Huang zhi-Jie Zhang ting-Yu Shuai Qi-Ni Zhan Gao-ren Li College of Materials Science and Engineering Sichuan UniversityChengdu 610065China

Fe-nitrogen-carbon(Fe-N-C)-and Co-nitrogen-carbon(Co-N-C)-based electrocatalysts have been widely concerned because of their high OER/ORR activity,low metal cost,and simple *** exploration of Fe-N-C and Co-N-C single atombased catalysts with high activity and stability to overcome the slow kinetics of oxygen reduction and oxygen evolution reactions is also the key to the development of efficient electrolytic water,fuel cells,and rechargeable metal-air ***-N-C and Co-N-C single atom-based electrocatalysts have the advantages of a high utilization rate of metal atoms and high electrocatalytic activity,and are ideal catalysts for promoting electrochemical energy conversion and *** general principles of designing Fe-N-C and Co-N-C single atom-based electrocatalysts are reviewed in this ***,the strategies to improve the bifunctional catalytic activity and stability are ***,the challenges and prospects of Fe-N-C and Co-N-C single atom-based catalysts are well *** review will provide a reference for the directed optimization of Fe-N-C and Co-N-C single atom-based catalysts.

关键词： Fe-N-C Co-N-C single atom bifunctional oxygen electrocatalysts

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无钟高炉炉料分布预测模型

工程科学学报 2017年第2期39卷 276-282页

作者：马财生任廷志燕山大学国家冷轧板带装备及工艺工程技术研究中心秦皇岛066004

为提高无钟高炉炉喉料面的预测精度,建立了考虑炉料运动的炉料分布数学模型.在分析炉料运动的基础上,指出了炉料运动是影响炉料堆积过程的重要因素,采用尺寸比1∶10的无钟布料器模型试验分析了不同炉料分速度对炉料堆积行为的影响,建立... 详细信息

为提高无钟高炉炉喉料面的预测精度,建立了考虑炉料运动的炉料分布数学模型.在分析炉料运动的基础上,指出了炉料运动是影响炉料堆积过程的重要因素,采用尺寸比1∶10的无钟布料器模型试验分析了不同炉料分速度对炉料堆积行为的影响,建立了考虑炉料运动因素的料堆轮廓预测模型,并通过数值方法确定了料堆的位置和料面轮廓曲线,应用于料面形状的预测.结果表明:炉料的运动是造成料堆两侧堆积角差异、料堆横截面面积变化以及料面轮廓改变的重要原因,料堆轮廓采用直线段和曲线相结合的方式进行构造,炉料的堆积角和曲线过渡区域长度作为重要的模型参数均考虑了炉料速度的影响,模型构造的轮廓接近真实料堆形状,应用该模型实现了炉喉料面的准确预测.

关键词：高炉无钟炉顶炉料料堆形状预测模型

Alginate oligosaccharide-mediated butyrate-HIF-1α axis improves skin aging in mice

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Journal of Pharmaceutical Analysis 2024年第5期14卷 678-692页

作者： ting Gao Yixuan Li Xiaoyu Wang Fazheng ren Department of Nutrition and Health College of Veterinary MedicineChina Agricultural UniversityBeijing100083China

The“gut-skin”axis has been proved and is considered as a novel therapy for the prevention of skin *** antioxidant efficacy of oligomannonic acid(MAOS)makes it an intriguing target for use to improve skin *** present study further explored whereby MAOS-mediated gut-skin axis balance prevented skin aging in *** data indicated the skin aging phenotypes,oxidative stress,skin mitochondrial dysfunction,and intestinal dysbiosis(especially the butyrate and HIF-1a levels decreased)in aging ***,fecal microbiota transplantation(FMT)from aging mice rebuild the aging-like ***,we demonstrated MAOS-mediated colonic butyrate-HIF-1a axis homeostasis promoted the entry of butyrate into the skin,upregulated mitophagy level and ultimately improving skin aging via HDAC3/PHD/HIF-1a/mitophagy loop in skin of ***,our study offered a better insights of the effectiveness of alginate oligosaccharides(AOS),promised to become a personalized targeted therapeutic agents,on gut-skin axis disorder inducing skin aging.

关键词： Alginate oligosaccharide Skin aging Butyrate HIF-1a Mitophagy

Graphene-loaded nickel−vanadium bimetal oxides as hydrogen pumps to boost solid-state hydrogen storage kinetic performance of magnesium hydride

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Transactions of Nonferrous Metals Society of China 2024年第8期34卷 2645-2657页

作者： Dong-qiang GAO Fu-ying WU zhi ZHANG Zi-chuan LU ren ZHOU Hu ZHAO Liu-ting ZHANG School of Energy and Power Jiangsu University of Science and TechnologyZhenjiang 212003China Instrumental Analysis Center Jiangsu University of Science and TechnologyZhenjiang 212003China School of Mechanical and Aerospace Engineering Nanyang Technological UniversitySingapore 639798Singapore

To modify the thermodynamics and kinetic performance of magnesium hydride(MgH_(2))for solid-state hydrogen storage,Ni_(3)V_(2)O_(8)-rGO(rGO represents reduced graphene oxide)and Ni_(3)V_(2)O_(8)nanocomposites were prepared by hydrothermal and subsequent heat *** beginning hydrogen desorption temperature of 7 wt.%Ni_(3)V_(2)O_(8)-rGO modified MgH_(2)was reduced to 208°C,while the additive-free MgH_(2)and 7 wt.%Ni_(3)V_(2)O_(8)doped MgH_(2)appeared to discharge hydrogen at 340 and 226°C,respectively.A charging capacity of about 4.7 wt.%H_(2)for MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO was achieved at 125°C in 10 min,while the dehydrogenated MgH_(2)took 60 min to absorb only 4.6 wt.%H_(2)at 215°*** microstructure analysis confirmed that the in-situ generated Mg_(2)Ni/Mg_(2)NiH4 and metallic V contributed significantly to the enhanced performance of MgH_(2).In addition,the presence of rGO in the MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO composite reduced particle aggregation tendency of Mg/MgH_(2),leading to improving the cyclic stability of MgH_(2)during 20 cycles.

关键词： hydrogen storage properties MgH_(2) graphene-loaded Ni−V bimetal oxides catalytic mechanism

Effects of environment and genotype-by-environment interaction on phenotype of Rorippa elata(Brassicaceae),an endemic alpine plant in the Hengduan mountains

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Journal of Plant Ecology 2024年第4期17卷 42-55页

作者： zhi-Qiang Du Yao-Wu Xing ting-Shen Han CAS Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla 666303China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Plant Diversity and Specialty Crops Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMengla 666303China

Global climate change poses a severe threat to mountain *** plasticity and local adaptation are two common strategies for alpine plant to cope with such *** may facilitate organismal adaptation to contrasting environments,depending on the influences of the environment or genotype or their interacted *** this study,we use an endemic alpine plant(Rorippa elata)in the Hengduan mountains(HDM)to unravel its phenotypic basis of adaptation strategy and evaluate the relative contributions of environment and genotype to its *** transplanted 37 genotypes of *** into two common gardens across low and high elevations(2800 vs.3800 m)during *** fitness-related traits were measured,including flowering probability and glucosinolates(GS)*** estimated the environmental or genotypic contributions to the phenotype and identified the main environmental *** results revealed that both environment and genotype-by-environment interactions contributed to the phenotypes of *** heterogeneity was identified as a key factor that explained 24%of the total phenotypic *** particular,genotypes of the northern HDM showed significantly higher plasticity in flowering probability than those of the southern ***,within the southern HDM,GS content indicated local adaptation to herbivory stresses for *** genotypes along *** conclusion,our results suggest that *** may have adapted to the alpine environment through species-level plasticity or regional-level local *** processes were shaped by either complex topography or interactions between genotype and mountain *** study provides empirical evidence on the adaptation of alpine plants.

关键词： alpine plant common garden genotype-by-environment Hengduan mountains local adaptation phenotypic plasticity