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Compressive property and energy absorption characteristic of interconnected porous Mg-Zn-Y alloys with adjusting Y addition

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journal of Magnesium and Alloys 2024年第1期12卷 171-185页

作者： j.A.Liu s.j.Liu B.Wang W.B.sun X.j.Liu Z.W.Han College of Materials science and Engineering Key Laboratory of Automobile Materials(Ministry of Education)Jilin UniversityChangchun 130022PR China Key Laboratory of Bionic Engineering(Ministry of Education) College of Biological and Agricultural EngineeringJilin UniversityChangchun130022PR China Weihai Institute for Bionics.j.lin University Weihai 264205PR China

In this study,interconnected porous Mg-2Zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption *** characterization methods were then applied to identify the microstructure of the porous Mg-Zn-Y and describe the details of the second *** tests were performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous *** experimental results showed that a high Y content promotes a microstructure refinement and increases the volume fraction of the second *** the Y content increases,different Mg-Zn-Y ternary phases appear:I-phase(Mg_(3)Zn_(6)Y),W-phase(Mg_(3)Zn_(3)Y_(2)),and LPsO phase(Mg_(12)ZnY).When the Y content ranges between 0.4%and 6%,the compressive strength increases from 6.30MPa to 9.23 MPa,and the energy absorption capacity increases from 7.33 Mj/m^(3)to 10.97 Mj/m^(3)at RT,which is mainly attributed to the phase composition and volume fraction of the second ***,the average energy absorption efficiency is independent of the Y *** addition,the compressive deformation behaviors of the porous Mg-Zn-Y are altered by the testing *** compressive strength and energy absorption capacity of the porous Mg-Zn-Y decrease due to the softening effect of the high temperature on the *** deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.

关键词： Porous magnesium Rare earth elements Microstructure Compressive behavior Energy absorption characteristic

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文献快报(5):社交媒体使用消极体验而非使用时长增加青少年自杀意念

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中国学校卫生 2024年第5期45卷 614-614页

作者： HAMILTON j LDALACK M BOYD s I 李琪(编译) Department of Psychology Rutgers University Piscataway NJ USA. Department of Psychology George Washington University Washington DC USA. Department of Psychiatry University of Pittsburgh Pittsburgh PA USA.

社交媒体使用与青少年自杀风险的关联受到广泛关注。匹兹堡大学David教授领衔的团队在美国各地招募了60名青少年进行了为期8周的监测,通过每日3次生态瞬时评估询问青少年社交媒体使用相关的消极体验(如感到焦虑)、积极体验(如受到鼓励)... 详细信息

社交媒体使用与青少年自杀风险的关联受到广泛关注。匹兹堡大学David教授领衔的团队在美国各地招募了60名青少年进行了为期8周的监测,通过每日3次生态瞬时评估询问青少年社交媒体使用相关的消极体验(如感到焦虑)、积极体验(如受到鼓励)及自杀意念,首次通过密集监测设计探讨青少年社交媒体体验与自杀意念间的关联,结果显示,频繁经历消极的社交媒体体验的青少年更可能报告自杀意念,而积极的社交媒体体验与自杀意念报告率降低有关。此外,未发现社交媒体的使用时间(视屏时间)与自杀意念间的显著关联。研究提示社交媒体经历可能是青少年自杀可修饰的风险因素,未来的研究应将增强青少年社交媒体的积极体验感作为改善青少年心理健康和预防自杀的目标,而不仅仅是限制视屏时间。

关键词：社交媒体匹兹堡大学自杀意念青少年自杀积极体验青少年心理健康监测设计消极体验

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single-atom Pt on carbon nanotubes for selective electrocatalysis

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Carbon Energy 2024年第1期6卷 63-71页

作者： samuel s.Hardisty Xiaoqian Lin Anthony R.j.Kucernak David Zitoun Department of Chemistry Bar Ilan Institute of Nanotechnology and Advanced Materials(BINA)Bar Ilan UniversityRamat GanIsrael Department of Chemistry Molecular Science Research HubImperial College LondonLondonUK

Utilizing supported single atoms as catalysts presents an opportunity to reduce the usage of critical raw materials such as platinum,which are essential for electrochemical reactions such as hydrogen oxidation reaction(HOR).Herein,we describe the synthesis of a Pt single electrocatalyst inside single-walled carbon nanotubes(sWCNTs)via a redox *** via electron microscopy,X-ray photoelectron microscopy,and X-ray absorption spectroscopy show the single-atom nature of the *** electrochemical behavior of the sample to hydrogen and oxygen was investigated using the advanced floating electrode technique,which minimizes mass transport limitations and gives a thorough insight into the activity of the *** single-atom samples showed higher HOR activity than state-of-the-art 30%Pt/C while almost no oxygen reduction reaction activity in the proton exchange membrane fuel cell operating *** selective activity toward HOR arose as the main fingerprint of the catalyst confinement in the sWCNTs.

关键词： confinement electrocatalysis hydrogen platinum single atom catalysts

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高质量发展背景下教师教育的内在机制与实施路径

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继续教育研究 2024年第9期 22-26页

作者：李彦欣樊清华万赫达山西医科大学国际教育学院山西太原030619

实现教师教育高质量发展是提升教育质量的基础与关键。教师教育具有公共性、人本性与创新性。推动教师教育高质量发展有利于提升教育质量、推动教师主动发展成长、深化教师专业化进程、推动教师教育走向专业化。实现教师教育高质量发展... 详细信息

实现教师教育高质量发展是提升教育质量的基础与关键。教师教育具有公共性、人本性与创新性。推动教师教育高质量发展有利于提升教育质量、推动教师主动发展成长、深化教师专业化进程、推动教师教育走向专业化。实现教师教育高质量发展应坚持党对教师教育事业的全面领导、做好人才培养工作、聚焦“发展目标”做好顶层设计、强化教师教育师资力量、完善教师教育评价体系,深层次引领教师教育高质量发展。

关键词：教师教育高质量发展内在机制实施路径

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A new approach to pedestal differentiation for soil loss estimation-a case study from a burnt area in north-central Portugal

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journal of Forestry Research 2024年第3期35卷 45-54页

作者： Frank G.A.Verheijen Martinho A.s.Martins sergio A.Prats.j.n j.Keizer Centre for Environmental and Marine studies(CEsAM) Department Environment and PlanningUniversity of Aveiro3810-193 AveiroPortugal Mediterranean Institute for Agriculture Environment and Development(MED-CHANGE)Institute for Advanced Studies and ResearchUniversity of EvoraPolo da MitraAp.947006-554 EvoraPortugal GeoBiociencias Geotecnologias E Geoengenharias(GEOBIOTEC)Department Environment and PlanningUniversity of Aveiro3810-193 AveiroPortugal

soil pedestals have long been used as qualitative indicators of soil splash *** rangelands,plant-capped pedestals,generally grass tussocks,have also been used to quantitatively estimate soil loss since the first half of the twentieth *** agricultural lands,forests,and bad-lands,stone-capped pedestals have been used as qualitative and semi-quantitative indicators of active,'extreme'*** work has been reported on using capstone pedestal data for quantifying soil *** postulate that three distinct capstone pedestal types may be present in any given location and that a detailed analysis of a pedestal height histogram may be used to recognize their *** analysis can subsequently inform if soil loss can be reliably estimated and if so,which of the existing methods using pedestal height data will provide more accurate *** three proposed capstone pedestal types are:(1)neo-pedestals formed underneath surface stones exposed by(partial)removal of the soil surface cover;(2)endo-pedestals formed underneath stones that were buried in the soil but have been exposed by erosion;and(3)phoenix-pedestals formed underneath stones from collapsed *** the pedestal height histogram of any given location,a skew to smaller heights may indicate the existence of endo-and/or phoenix-pedestals,which may be revealed as a bi-(or tri)modal distribution when using a smaller bin *** concept was applied to a case study where soil loss had been monitored for control plots and mulched plots during a 5-year period following wildfire in a eucalypt *** measured pedestal heights and used methods to quantitatively assess soil loss from soil pedestal data in the available *** pedestal data at the end of the 5-year period under or overestimated soil loss in the control treatment,with results ranging from 60 to 115%of measured soil loss,depending on the *** is postulated that phoenix-and endo-pedestals may be a driving fact

关键词： soil pedestals Mulch Wildfire soil erosion Char

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Mathematical modelling of ball and plate system with experimental and correlation function-based model validation

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Control Theory and Technology 2024年第2期22卷 326-341页

作者： T.R.Dil Kumar s.j.Mija Department of Electrical Engineering National Institute of Technology CalicutKozhikode673601KeralaIndia

The ball and plate system is an inherently nonlinear under actuated benchmark system used for validating the performance of various control schemes. A mathematical model depicting the dynamics close to that of the system is very much required for such a test bed. In this correspondence, the complete nonlinear model, a simplified nonlinear model, and a linearized model of the ball and plate system are developed. The system comprises a ball and plate mechanism and a rotary servo unit. The ball and plate mechanism is modelled using the Euler–Lagrange method, whereas the rotary servo subsystem is modelled from the first principles. The nonlinear model of the combined system is developed by including the dynamics of the servo motor with gear and rolling resistance between the ball and the plate. The simplified nonlinear model of the system is obtained with suitable assumptions. The model is linearized around the operating point using the jacobian. The validity of the developed models is investigated through correlation function analysis. The open-loop response of the three models, viz., nonlinear, simplified nonlinear, and linearized models, is analyzed in the MATLAB/simulink platform. since the open-loop system is unstable, the experimental validation of the model is performed with a double-loop PsO (particle swarm optimization) PID control scheme.

关键词： Ball and plate system Correlation function Model validation Particle swarm optimization(PsO) PsO PID controller

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架空裸导线绝缘包覆用硅胶绝缘性能的研究

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化学与粘合 2024年第1期46卷 38-43页

作者：潘正焘麦嘉颖石兰兰赖敏琪董铭达广东电网有限责任公司清远清新供电局广东清远511500

为保障架空裸导线使用的安全性,需提升架空裸导线绝缘包覆用硅胶绝缘性能,为此以甲基乙烯基硅橡胶为主材料,氮化硼作为填充料,制备氮化硼含量分别为10 phr、15 phr和20 phr的包覆用硅胶样本j01、j02、j03,并对样本的黏度、交联密度、力... 详细信息

为保障架空裸导线使用的安全性,需提升架空裸导线绝缘包覆用硅胶绝缘性能,为此以甲基乙烯基硅橡胶为主材料,氮化硼作为填充料,制备氮化硼含量分别为10 phr、15 phr和20 phr的包覆用硅胶样本j01、j02、j03,并对样本的黏度、交联密度、力学性能、耐电弧烧蚀老化性能、电绝缘性能展开测试。测试结果显示:3个样本在相同固化时间内,j02样本的黏度结果最佳,均维持在30000 mPa·s上下;3个样本的交联密度结果最高值分别达到2.06×10^(5)mol/g、3.11×10^(5)mol/g、3.08×10^(5)mol/g,j02的拉伸强度最高值为0.83 MPa、断裂伸长率最高值为933%、撕裂强度最高值为5.56 MPa,j02的烧蚀程度严重程度最小,j01的烧蚀程度最显著;j02样本在不同电击强度和持续时间下的击穿强度结果最小,均在14.5 kV/mm左右,另外2种样本最大击穿强度分别在18.2 kV/mm和17.6 kV/mm,因此,氮化硼含量为15 phr的样本绝缘性能最佳。

关键词：架空裸导线绝缘包覆硅胶绝缘性能烧蚀程度击穿强度交联密度

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sR8278改善时差所致小鼠泪腺功能紊乱的转录组学分析

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眼科新进展 2024年第4期44卷 264-269页

作者：黄深振齐迪裴晓婷路顶立司宏丽黄杜鎏睿张文潇巴梦茹轩书婷李志杰郑州大学人民医院河南省人民医院河南大学人民医院河南省立眼科医院河南省眼科研究所河南省郑州市450003

目的探讨核受体亚家族1 D组成员1(NR1D1)合成拮抗剂sR8278在改善时差诱导的小鼠眶外泪腺结构和功能损伤方面的作用及其机制。方法 36只健康的8~10周龄野生型C57BL/6j小鼠在12 h光照/12 h黑暗循环的昼夜节律箱内适应2周后随机分为3组:... 详细信息

目的探讨核受体亚家族1 D组成员1(NR1D1)合成拮抗剂sR8278在改善时差诱导的小鼠眶外泪腺结构和功能损伤方面的作用及其机制。方法 36只健康的8~10周龄野生型C57BL/6j小鼠在12 h光照/12 h黑暗循环的昼夜节律箱内适应2周后随机分为3组:正常组(12 h光照/12 h黑暗循环的昼夜节律箱饲养)、时差组(8 h前移的12 h光照/12 h黑暗循环的昼夜节律箱饲养)及时差+sR8278组(8 h前移的12 h光照/12 h黑暗循环的昼夜节律箱饲养,并给予25 mg·kg^(-1)的sR8278干预),每组12只,共干预5 d。干预结束后,收集各组小鼠的活动度和核心体温,记录小鼠的泪液分泌量,并对泪腺组织进行称重和泪腺细胞大小测量。采用免疫组织化学方法对小鼠眶外泪腺进行组织学评估。提取泪腺RNA进行包含NR1D1的高通量RNA-seq分析,并对获得的转录组数据进行KEGG和GO功能富集分析。结果与正常组相比,时差组小鼠白天活动度较高,夜间活动度较低,白天核心体温较高,夜间核心体温较低,差异均有统计学意义(均为PsR8278组小鼠白天活动度较低,夜间活动度较高,白天核心体温较低,夜间核心体温较高,差异均有统计学意义(均为PsR8278组小鼠泪腺重量及泪液分泌量增加,泪腺细胞减小,差异均有统计学意义(均为P达量较高;与时差组相比,时差+sR8278组小鼠夜晚泪腺中NR1D1表达量较低,差异均有统计学意义(均为PsR8278组共有947个显著性差异基因,其中显著性上调基因43个,显著性下调基因904个,信号通路差异最大的为Notch信号通路。结论 sR8278通过靶向抑制NR1D1,有效增强了时差小鼠的泪液分泌功能,其过程可能是通过Notch信号通路完成的。

关键词：时差 sR8278 泪腺功能紊乱小鼠

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The CCD instrument background of the sMILE sXI

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Earth and Planetary Physics 2024年第1期8卷 15-24页

作者： M.W.j.Hubbard O.Hetherington D.j.Hall T.W.Buggey s.Parsons T.Arnold A.Holland C.Pagani s.sembay Centre for Electronic Imaging The Open UniversityMilton KeynesMK76AAUK X-ray and Observational Astronomy Group Department of Physics&AstronomyUniversity of LeicesterLE17RHUK

The EsA and CAs sMILE mission orbit is highly elliptical and will pass through multiple radiation *** soft X-ray Imager(sXI)instrument aboard has a radiation shutter door designed to close when the surrounding radiation flux is *** shutter door will close when passing below an altitude threshold to protect against trapped particles in the Earth’s Van Allen ***,two radiation environments can be approximated based on the shutter door position:open and *** instrument background for the CCDs(Charge-Coupled Devices)that form the focal plane array of the sXI were evaluated for the two *** to the correlation of the space environment with the solar cycle,the solar minima and maxima,the background was also evaluated at these two *** results demonstrated that the highest instrument background will occur during solar minima due to the main contributing source being Galactic Cosmic Rays(GCRs).It was also found that the open background was highest for solar minima and that the closed background was highest during solar *** is due to the radiation shutter door acting as a scattering centre and the changes in the energy flux distribution of the GCRs between the two solar extremes.

关键词： instrument background X-ray astronomy space radiation

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Water and thermal conditions variation and the vegetation response at semi⁃ arid Basin

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shengtai Xuebao 2024年第16期44卷 7198-7212页

作者： Fang Q. Zhang s. Wang G. Wang Y. Duan L. Liu T. Yao j. school of Water Conservancy and Hydropower Engineering North China Electric Power University Beijing 102206 China College of Water sciences Beijing Normal University Beijing 100875 China The College of Water Conservancy and Civil Engineering Inner Mongolia Agricultural University Hohhot 010018 China The school of Ecology and Environment Inner Mongolia University Hohhot 010021 China

Recently, most semi⁃arid basins in China have experienced vegetation greening under significant water and thermal conditions changes, which has exacerbated the shortage of water resources despite the positive effect of increasing carbon sinks and reducing carbon emissions. The study of vegetation response under variations of water and thermal conditions can help to understand the mechanism of the balance between the hydrological processes and vegetation pattern and is of great significance for the sustainable utilization of water resources and ecological protection. However, few studies have focused on the time⁃periodic and segmented response mechanisms of vegetation dynamics to variations of water and thermal conditions, resulting in unclear mechanisms of trade⁃off between vegetation greening and water resources. This study analyzed the varied trends of water and thermal conditions and discussed the spatio⁃temporal response of vegetation from two points: overall trends and varied processes at the upper and middle Hailar River Basin from 1980 to 2012 by using trends and wavelet period analysis. The results show that: (1) spatially, the average annual precipitation increased and the temperature decreased from west (grassland) to east (forest). Compared with the grassland area, the runoff and the Normalized Difference Vegetation Index (NDVI) in the forest area showed larger, and indicated slower warming and larger precipitation declining. (2) Temporally, the average annual precipitation and the runoff slightly decreased with a trend of 10 mm/ 10 a and 19.3 mm/ 10 a, respectively; the average annual temperature and NDVI in the growing season increased significantly with a trend of 0.65 ℃ / 10 a and 0.003—0.006/ 10 a, respectively. The results suggested that warming and drying inhibited the runoff and increased the vegetation growth, even in the context of precipitation increased and smooth increasing trend of temperature after 1998, showing the accumulative effect of w

关键词： runoff variations vegetation response water and thermal conditions water stress

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