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Properties and microstructure of copper–titanium alloys with magnesium additions

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Rare Metals 2024年第5期43卷 2290-2299页

作者： Lue Huang Li-Jun Peng jiang Li Xu-Jun Mi Gang Zhao Guo-Jie Huang Hao-Feng Xie Yi-Cheng Cao wen-Jing Zhang Zhen Yang State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co. Ltd. GRIMAT Engineering Institute Co. Ltd. School of Materials Science and Engineering Northeastern University General Research Institute for Nonferrous Metals China Academy of Space Technology China Nonferrous Metals Mining Group (Tianjin) Co.Ltd

The volume fractions and morphology of precipitates in precipitation-strengthened Cu-Ti alloys,which precipitate mainly as continuous and discontinuous precipitates,are important for the application of the alloy.This study employed hardness and electrical conductivity tests transmission electron microscopy （TEM）,atom probe tomography （APT）,and first-principles calculations to demonstrate that the addition of Mg is effective for accelerating nanosized continuous β'-Cu4Ti precipitation as well as for suppressing the precipitation of coarse lamellar discontinuous β-Cu4Ti precipitates along the grain boundaries,resulting in Cu-Ti alloys with high yield strength and good electrical conductivity.The results showed that the continuous precipitation of β'-Cu4Ti was accelerated by the Mg additions,which reduced the supersaturation of the matrix,thereby reducing the chemical driving force for the discontinuous precipitates.On the other hand,Mg additions increased the mismatch between the discontinuous β-Cu4Ti precipitates and matrix decreased the nucleation rate of the discontinuous precipitates,and increased the spacing of the discontinuous precipitation layer,resulting in a lower growth rate of the discontinuous precipitates.Therefore,the addition of Mg to Cu-Ti alloys enhances the strength and improves the resistance to over-ageing.

关键词： Cu-Ti-Mg alloy Precipitation hardening Discontinuous precipitation Continuous precipitation Microstructure formation mechanism

Inferring Mycobacterium Tuberculosis Drug Resistance and Transmission using Whole-genome Sequencing in a High TB-burden Setting in China

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Biomedical and Environmental Sciences 2024年第2期37卷 157-169页

作者： FAN Yu Feng LIU Dong Xin CHEN Yi Wang OU Xi Chao MAO Qi Zhi YANG Ting Ting WANG Xi jiang HE wen Cong ZHAO Bing LIU Zhen jiang ABULIMITI Maiweilanjiang AIHEMUTI Maimaitiaili GAO Qian ZHAO Yan Lin Key Laboratory of Medical Molecular Virology(MOE/NHC/CAMS) School of Basic Medical SciencesShanghai Medical CollegeFudan UniversityShanghai 200032China National Tuberculosis Reference Laboratory Chinese Center for Disease Control and PreventionBeijing 102206China Hangzhou Red Cross Hospital Hangzhou 310005ZhejiangChina Xinjiang Uygur Autonomous Region Center for Disease Control and Prevention Urumqi 830026XinjiangChina Tuberculosis Dispensary of Kashgar Prefecture Kashgar 844099XinjiangChina

Objective China is among the 30 countries with a high burden of tuberculosis(TB)worldwide,and TB remains a public health concern.Kashgar Prefecture in the southern Xinjiang Autonomous Region is considered as one of the highest TB burden regions in China.However,molecular epidemiological studies of Kashgar are lacking.Methods A population-based retrospective study was conducted using whole-genome sequencing(WGS)to determine the characteristics of drug resistance and the transmission patterns.Results A total of 1,668 isolates collected in 2020 were classified into lineages 2(46.0%),3(27.5%),and 4(26.5%).The drug resistance rates revealed by WGS showed that the top three drugs in terms of the resistance rate were isoniazid(7.4%,124/1,668),streptomycin(6.0%,100/1,668),and rifampicin(3.3%,55/1,668).The rate of rifampicin resistance was 1.8%(23/1,290)in the new cases and 9.4%(32/340)in the previously treated cases.Known resistance mutations were detected more frequently in lineage 2 strains than in lineage 3 or 4 strains,respectively:18.6%vs.8.7 or 9%,P<0.001.The estimated proportion of recent transmissions was 25.9%(432/1,668).Multivariate logistic analyses indicated that sex,age,occupation,lineage,and drug resistance were the risk factors for recent transmission.Despite the low rate of drug resistance,drug-resistant strains had a higher risk of recent transmission than the susceptible strains(adjusted odds ratio,1.414;95%CI,1.023–1.954;P=0.036).Among all patients with drug-resistant tuberculosis(DR-TB),78.4%(171/218)were attributed to the transmission of DR-TB strains.Conclusion Our results suggest that drug-resistant strains are more transmissible than susceptible strains and that transmission is the major driving force of the current DR-TB epidemic in Kashgar.

关键词： Mycobacterium tuberculosis Whole-genome sequencing(WGS) Transmission Drug resistance Xinjiang

Two-photon live imaging of direct glia-to-neuron conversion in the mouse cortex

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Neural Regeneration Research 2024年第8期19卷 1781-1788页

作者： Zongqin Xiang Shu He Rongjie Chen Shanggong Liu Minhui Liu Liang Xu Jiajun Zheng Zhouquan jiang Long Ma Ying Sun Yongpeng Qin Yi Chen wen Li Xiangyu Wang Gong Chen wenliang Lei Guangdong-Hong Kong-Macao Institute of CNS Regeneration(GHMICR) Jinan UniversityGuangzhouGuangdong ProvinceChina Department of Neurosurgery The First Affiliated HospitalJinan UniversityGuangzhouGuangdong ProvinceChina Laboratory for Neuroimmunology in Health and Diseases Guangzhou First People’s HospitalSchool of MedicineSouth China University of TechnologyGuangzhouGuangdong ProvinceChina VIB-KU Leuven Center for Brain&Disease Research LeuvenFlemish RegionBelgium

Over the past decade,a growing number of studies have reported transcription factor-based in situ reprogramming that can directly conve rt endogenous glial cells into functional neurons as an alternative approach for n euro regeneration in the adult mammalian central ne rvous system.Howeve r,many questions remain regarding how a terminally differentiated glial cell can transform into a delicate neuron that forms part of the intricate brain circuitry.In addition,concerns have recently been raised around the absence of astrocyte-to-neuron conversion in astrocytic lineage-tra cing mice.In this study,we employed repetitive two-photon imaging to continuously capture the in situ astrocyte-to-neuron conversion process following ecto pic expression of the neural transcription factor NeuroD1 in both prolife rating reactive astrocytes and lineage-tra ced astrocytes in the mouse cortex.Time-lapse imaging over several wee ks revealed the ste p-by-step transition from a typical astrocyte with numero us short,tapered branches to a typical neuro n with a few long neurites and dynamic growth cones that actively explored the local environment.In addition,these lineage-converting cells were able to migrate ra dially or to ngentially to relocate to suitable positions.Furthermore,two-photon Ca2+imaging and patch-clamp recordings confirmed that the newly generated neuro ns exhibited synchronous calcium signals,repetitive action potentials,and spontaneous synaptic responses,suggesting that they had made functional synaptic connections within local neural circuits.In conclusion,we directly visualized the step-by-step lineage conversion process from astrocytes to functional neurons in vivo and unambiguously demonstrated that adult mammalian brains are highly plastic with respect to their potential for neuro regeneration and neural circuit reconstruction.

关键词： astrocyte-to-neuron conversion Ca2+imaging direct lineage conversion glia astrocyte in vivo reprogramming lineage-tracing mice NeuroD1 neuron two-photon imaging

Vertical two-dimensional WS_(2)flakes grown on flexible CNT film for excellent electrochemical performance

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Rare Metals 2024年第1期43卷 164-174页

作者： Qian Gong Jing-Yun Zou Ming Ren Si-Qi Zhu Yu-Rong Zhou Li-Ming Zhao Jian Chen Yu-Long Wu jiang-Tao Di Li-Xing Kang Qing-wen Li School of Nano-Tech and Nano-Bionics University of Science and Technology of ChinaHefei 230026China Key Laboratory of Multifunctional Nanomaterials and Smart Systems Division of Advanced MaterialsSuzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhou 215123China jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Physical Science and TechnologySuzhou University of Science and TechnologySuzhou 215009China

Soft electrochemical actuators that can generate mechanical motions in response to electrical stimuli can be used as artificial muscles in microscale robots.The electrode materials are the key component of the electrochemical actuator because they limit the ion diffusion and accumulation processes and thus affect the deformation in fast response-time and potential engineering applications.Low-dimensional materials,such as one-dimensional(1D)CNT and two-dimensional(2D)vertically stood WS_(2),are great electrode due to their good electrochemical stability and high surface-to-volume ratios,but show limited performances when being used on their own in the actuators because of low reconstruction or low conductivity.A combination of 1D CNT and 2D WS_(2)could form a heterojunction with both high electrochemical activity and great mechanical stability.Herein,by depositing highly disordered graphene nanosheets(HDGNs)on CNT films and then WS_(2)on the formed low-dimensional nanocarbon film,a hybrid WS_(2)/HDGN/CNT film was synthesized through a multistep CVD method.Vertically grown WS_(2)nanosheets were achieved by taking advantage of HDGNs which limits CNTs sliding.So,the volume expansion caused by the transition from WO_(3)to WS-2can force the vertical growth of WS_(2).This hybrid film shows excellent electrochemical properties,such as high specific capacitance and high rate performance.Soft actuators based on the WS_(2)/HDGN/CNT films show good actuating performance,including stability and reconfigurability.

关键词： CNT Graphene Vertically growth WS_(2) Electrochemical actuators

“双减”背景下义务教育阶段数学教师职业认同的实证研究——基于云贵两省2892位教师的调查数据

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数学教育学报 2024年第2期33卷 64-71页

作者：姜文贵州师范大学数学科学学院贵州贵阳550025

教师职业认同是教师教育研究的热点主题之一.采用问卷和访谈调查了云贵两省2892位义务教育阶段数学教师在“双减”政策背景下的职业认同感,结果显示:“双减”政策背景下义务教育阶段数学教师职业认同的总体水平处于新高;参与课后延时服... 详细信息

教师职业认同是教师教育研究的热点主题之一.采用问卷和访谈调查了云贵两省2892位义务教育阶段数学教师在“双减”政策背景下的职业认同感,结果显示:“双减”政策背景下义务教育阶段数学教师职业认同的总体水平处于新高;参与课后延时服务可以提高义务教育阶段数学教师的职业归属感和职业认同感;教师的职业认同具有性别、任教学段、学历和职称上的显著差异,而在城乡、地区上差异不显著;是否师范院校毕业对义务教育阶段数学教师的职业认同不产生影响.

关键词：双减义务教育数学教师教师职业认同教育实证研究

The interaction between temperature and precipitation on the potential distribution range of Betula ermanii in the alpine treeline ecotone on the Changbai Mountain

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Forest Ecosystems 2024年第1期11卷 42-51页

作者： Yu Cong Yongfeng Gu wen J.Wang Lei Wang Zhenshan Xue Yingyi Chen Yinghua Jin Jiawei Xu Mai-He Li Hong S.He Ming jiang Northeast Institute of Geography and Agroecology Chinese Academy of SciencesChangchun 130102China Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains Ministry of EducationSchool of Geographical SciencesNortheast Normal UniversityChangchun 130024China School of Natural Resources University of MissouriColumbiaMO 65211USA Swiss Federal Institute for Forest Snow and Landscape Research WSLCH-8903 BirmensdorfSwitzerland School of Life Science Hebei UniversityBaoding 071000China

Alpine treeline ecotones are highly sensitive to climate warming.The low temperature-determined alpine treeline is expected to shift upwards in response to global warming.However,little is known about how temperature interacts with other important factors to influence the distribution range of tree species within and beyond the alpine treeline ecotone.Hence,we used a GF-2 satellite image,along with bioclimatic and topographic variables,to develop an ensemble suitable habitat model based on the species distribution modeling algorithms in Biomod2.We investigated the distribution of suitable habitats for B.ermanii under three climate change scenarios(i.e.,low(SSP126),moderate(SSP370)and extreme(SSP585)future emission trajectories)between two consecutive time periods(i.e.,current-2055,and 2055-2085).By 2055,the potential distribution range of B.ermanii will expand under all three climate scenarios.The medium and high suitable areas will decline under SSP370 and SSP585scenarios from 2055 to 2085.Moreover,under the three climate scenarios,the uppermost altitudes of low suitable habitat will rise to 2,329 m a.s.l.,while the altitudes of medium and high suitable habitats will fall to 2,201 and2,051 m a.***.l.by 2085,respectively.Warming promotes the expansion of B.ermanii distribution range in Changbai Mountain,and this expansion will be modified by precipitation as climate warming continues.This interaction between temperature and precipitation plays a significant role in shaping the potential distribution range of B.ermanii in the alpine treeline ecotone.This study reveals the link between environmental factors,habitat distribution,and species distribution in the alpine treeline ecotone,providing valuable insights into the impacts of climate change on high-elevation vegetation,and contributing to mountain biodiversity conservation and sustainable development.

关键词： Biomod2 Birch Climate change Climate scenarios Habitat suitability Range shift Treeline species

Experiments and simulation on the overall DMG of long-haul cascade FM-EDFA systems

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Chinese Optics Letters 2024年第4期22卷 53-59页

作者：江歆睿武保剑严伟文峰邱昆 Key Laboratory of Optical Fiber Sensing and Communications Ministry of EducationUniversity of Electronic Science and Technology of ChinaChengdu 611731China

All-fiber few-mode erbium-doped fiber amplifiers(FM-EDFAs) with isolation and wavelength division multiplexers(IWDMs)have been developed to enable flexible pumping in different directions. The FM-EDFA can achieve >30 d B modal gain with<0.3 d B differential modal gain(DMG). We experimentally simulate the DMG performance of a cascade FM-EDFA system using the equivalent spectrum method. The overall DMG reaches 1.84 d B after 10-stage amplification. We also build a recirculating loop to simulate the system, and the developed FM-EDFA can support transmission up to 3270 km within a 2 d B overall DMG by optimizing the few-mode fiber length in the loop.

关键词： mode division multiplexing few-mode erbium-doped fiber amplifier gain equalization

The effect of secondary phase on corrosion behaviors of the titanium–zirconium–molybdenum alloy

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Tungsten 2024年第2期6卷 342-354页

作者： Song-Wei Ge Ping Hu Jie Deng Shi-Lei Li Hai-Rui Xing Jia-Yu Han Xing-jiang Hua Li Wang Jun-Zhou Yang Bo Jin wen Zhang Kuai-She Wang School of Metallurgy Engineering Xi’an University of Architecture and TechnologyXi’an 710055China National and Local Joint Engineering Research Center for Functional Materials Processing Xi’an University of Architecture and TechnologyXi’an 710055China Western Xinxing Rare and Precious Metals Co. Ltd.Shangluo 726000China Northwest Institute for Non-Ferrous Metal Research Xi’an 710016China

As the range of applications for molybdenum and its alloys has expanded,the corrosive environment for molybdenum alloys has become more demanding.In the past,the content of doping elements has been studied to investigate their infl uence on the corrosion performance of titanium–zirconium–molybdenum(TZM)alloys.In this paper,it is considered that the second phase in the alloy is the main factor aff ecting the corrosion performance of TZM alloys.By comparing the corrosion behavior of molybdenum metal and TZM alloy,the eff ect of the secondary phase on corrosion behaviors of TZM alloy has been investigated.The results show that the second phase reduces the corrosion resistance of the TZM alloy.The potential of the second phase is 73.7 mV higher than that of the Mo matrix,which contributes to the formation of microscopic electric couples.Under the action of microscopic electric couples,pitting corrosion is preferentially formed at the interface between the second phase and the matrix,which accelerates the corrosion of the matrix.This paper provides a theoretical basis for the application of TZM alloys in corrosive environments.

关键词： Secondary phase Electrochemical corrosion Titanium–zirconium–molybdenum(TZM) Galvanic corrosion Corrosion resistance

考虑温度变化下三层复合衬垫中重金属污染物一维运移理论模型

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岩土力学 2024年第2期45卷 417-432页

作者：江文豪冯晨李江山中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室湖北武汉430071 中国科学院大学北京100049 中国科学院武汉岩土力学研究所污染泥土科学与工程湖北省重点实验室湖北武汉430071

针对考虑温度变化下由土工膜(geomembrane,简称GM)+土工复合膨润土衬垫(geosynthetic clay liner,简称GCL)+压实黏土衬垫(compacted clay liner,简称CCL)组成的3层复合衬垫中重金属污染物一维运移问题,基于相关假定发展得到了热传导与... 详细信息

针对考虑温度变化下由土工膜(geomembrane,简称GM)+土工复合膨润土衬垫(geosynthetic clay liner,简称GCL)+压实黏土衬垫(compacted clay liner,简称CCL)组成的3层复合衬垫中重金属污染物一维运移问题,基于相关假定发展得到了热传导与重金属污染物运移的控制方程,并建立了相应理论模型。通过有限差分,对所建理论模型进行了数值求解。随后,开展了与试验结果、解析解计算结果以及其他数值解计算结果的对比分析,验证了该模型的合理性。最后,以Cd^(2+)为例,分析和讨论了不同因素对运移规律的影响。结果表明,上部温度升高会使复合衬垫中Cd^(2+)的运移通量和底部浓度增大,但会使其上部浓度降低。热扩散效应对运移行为的影响会随Soret系数ST的增大而变显著,当ST为0.001、0.005、0.01、0.05、0.1 K^(-1)时,所定义的击穿时间tb依次为37.9、37.2、36.4、31.2、26.5 a。GCL和CCL最大吸附量的增大均会使t_(b)近似线性增加,且在一定渗沥液水头h_(b)下,t_(b)随GCL和CCL厚度的增大呈线性增大趋势。此外,当h_(b)从0.5m增大到1.0m时,t_(b)平均降低了8.33 a。在工程实践中,可结合GCL和CCL的吸附性能和厚度来设计复合衬垫,同时应考虑温度变化对阻隔效果的影响。

关键词：温度变化热传导重金属污染物运移 3层复合衬垫理论模型击穿时间