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Attaining synergetic equilibrium of electrical conductivity and tensile strength in GQDs@GN/Cu composites through multi-scale intragranular and intergranular reinforcements

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Rare Metals 2024年第1期43卷 366-379页

作者： Shuang-yin Zhang Liang Liu Rui Bao Jian-Hong yi Sheng-da Guo Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China Key Laboratory of Advanced Materials of Yunnan Province Kunming University of Science and TechnologyKunming 650093China Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000China

The configuration and quality of reinforcements, as well as the robustness of interfacial bonding,holding a critical significance in determining the concurrence between electrical conductivity and mechanical strength in metal matrix composites. In this study, citric acid was employed as the precursor for synthesizing multiscale carbon nanomaterials(graphene quantum dots and graphene, abbreviated as GQDs and GN). The GQDs@GN/Cu composites were fabricated through a segmented ball milling process in conjunction with subsequent spark plasma sintering(SPS). The intragranular GQDs and intergranular GQDs@GN had synergistically reinforced Cu composites through Orowan strengthening, load transfer strengthening and refinement strengthening. Furthermore,the robust interface bonding between GQDs@GN and Cu effectively mitigated interfacial impedance stemming from electron-boundary scattering. The yield strength and ultimate tensile strength of the GQDs@GN/Cu composites were recorded as 270 and 314 MPa, respectively, representing an improvement of 92 and 28% over pure Cu, while maintaining electrical conductivity at a level comparable to that of pure Cu. This study advances the understanding of the possibility of realizing a synergistic compatibility between electrical conductivity and mechanical strength in Cu composites.

关键词： Cu matrix composites Interface bonding Mechanical property Graphene quantum dots(GQDs) Electrical conductivity

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高稳定度可见/短波红外在轨相对定标监测系统关键技术研究

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光谱学与光谱分析 2014年第4期34卷 927-931页

作者：刘懿尹达一中国科学院上海技术物理研究所上海200083 中国科学院大学北京100049

针对高稳定度遥感器在轨相对定标监测系统关键技术进行研究，阐述了工作原理和关键技术。研制了基于可见/短波红外双波段陷阱结构的高稳定度定标探测器组件，通过选择高灵敏度单元可见和短波红外光电探测器，一方面使探测器组件工作在... 详细信息

针对高稳定度遥感器在轨相对定标监测系统关键技术进行研究，阐述了工作原理和关键技术。研制了基于可见/短波红外双波段陷阱结构的高稳定度定标探测器组件，通过选择高灵敏度单元可见和短波红外光电探测器，一方面使探测器组件工作在线性更好、暗电流更低的零偏置光伏电路模式，另一方面使探测器组合成为复合型陷阱光机探测模式，并在模拟前放电路和数据采集环节进行了关键参数设计，完成了星载定标辐射源输出辐射的高稳定度相对定标监测系统设计。通过实验室内积分球以及国家计量技术机构提供的标准灯的辐射测试结果表明，系统获取的码值相对标准方差达到0.030％～0.046％（可见通道）和0.040％～0.059％（短波红外通道），实现了相对定标系统的高稳定度监测，为未来遥感器在轨相对定标提供一种优良的解决方案。

关键词：在轨定标可见近红外陷阱探测高稳定度监测

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PET imaging of cerebral metabolic change in tinnitususing ^(18)F-FDG

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Nuclear Science and Techniques 2000年第4期11卷 247-252页

作者： TIAN Jia-He, WANG Hong-Tian, yin da-yi, YAO Shu-Lin, SHAO Ming-Zhe, YANG Wei-Yan, JIANG Si-Chang (The PLA General Hospital, Beijing 100853) 解放军总医院北京 100853

Tinnitus is an auditory disorder hardly assessable by clinical technology. PET imaging of the brain in 13 cases with and 10 without tinnitus was undertaken at 40 min after injection of 280-440 MBq 18F-FDG. To ensure the quality of the PET study, all cases followed a normalized procedure with visual and auditory blockage. CT/MRI imaging and routine acoustic tests were carried out in all subjects. PET revealed that an increased uptake of 18F-FDG at left med-temporal lobe (primary auditory center, PAC) present exclusively in tinnitus, regardless the side of hearing hallucination. Significant asymmetry was noted between left and right PAC, but not at other cortex area. While control cases showed no asymmetric uptake between two hemispheres. The abnormal PAC uptake did not respond to external pure sound stimulus, nor did it relate to the seventy of hearing loss assessed by acoustic tests. No anatomical or morphological alteration could be proven on CT/MRI. In conclusion, PET/18F-FDG objectively revealed an increased metabolic change at left PAC in tinnitus, which is of diagnostic value; and there is evidence suggesting tinnitus is most likely induced by a functional change in the brain.

关键词： PET ^18F-FDC 氟18 放射性核素标记正电子发射X线断层摄影术放射性核素显像耳鸣诊断

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Magnetic Fields Reduce Apoptosis by Suppressing Phase Separation of Tau-441

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Research 2024年第1期2023卷 181-197页

作者： Wen-Juan Lin Wen-Pu Shi Wan-yi Ge Liang-Liang Chen Wei-Hong Guo Peng Shang da-Chuan yin Key Laboratory for Space Bioscience and Biotechnology School of Life SciencesNorthwestern Polytechnical University127 Youyixi RoadXi'an 710072ShaanxiPR China

The biological effects of magnetic fields(MFs)have been a controversial ***,in recent years,there has been increasing evidence that MFs do affect biological ***,the physical mechanism remains ***,we show that MFs(16 T)reduce apoptosis in cell lines by inhibiting liquid–liquid phase separation(LLPS)of Tau-441,suggesting that the MF effect on LLPS may be one of the mechanisms for understanding the“mysterious”magnetobiological *** LLPS of Tau-441 occurred in the cytoplasm after induction with *** phase-separated droplets of Tau-441 recruited hexokinase(HK),resulting in a decrease in the amount of free HK in the *** cells,HK and Bax compete to bind to the voltage-dependent anion channel(VdaC I)on the mitochondrial membrane.A decrease in the number of free HK molecules increased the chance of Bax binding to VdaC I,leading to increased Bax-mediated *** the presence of a static MF,LLPS was marked inhibited and HK recruitment was reduced,resulting in an increased probability of HK binding to VdaC I and a decreased probability of Bax binding to VdaC I,thus reducing Bax-mediated *** findings revealed a new physical mechanism for understanding magnetobiological effects from the perspective of *** addition,these results show the potential applications of physical environments,such as MFs in this study,in the treatment of LLPS-related diseases.

关键词： inhibited Apoptosis finding

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椭偏测量法的油膜紫外可见-近红外光谱光谱偏振特性研究

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光谱学与光谱分析 2019年第6期39卷 1661-1666页

作者：李清灵尹达一中国科学院大学北京100049 中国科学院上海技术物理研究所上海200083 中国科学院红外探测与成像技术重点实验室上海200083

为实现水面溢油目标的偏振遥感,选择合适的波段和观测角度,需要油膜的光谱偏振特性数据作支撑。在实验室采用椭偏测量的方法,针对不同厚度机油油膜和纯净水作为背景样本,测量了不同观测角度下从紫外到近红外波段(270~900nm)的镜面反射... 详细信息

为实现水面溢油目标的偏振遥感,选择合适的波段和观测角度,需要油膜的光谱偏振特性数据作支撑。在实验室采用椭偏测量的方法,针对不同厚度机油油膜和纯净水作为背景样本,测量了不同观测角度下从紫外到近红外波段(270~900nm)的镜面反射光谱偏振参数:辅助角ψ和相位差Δ,并对在相同条件下油和水的测量结果作对比。分析表明除布儒斯特角附近位置外,不同厚度的油膜与水的起偏特性在各观测角都存在差异。通过在45°入射角所测的ψ和Δ,得到水/油样本的光谱折射率和消光系数,水折射率经过偏移修正后,与Schiebener水折射率模型的标准差为3×10^-5。根据之前得到的油/水参数,对油膜在水背景的物理现象作薄油膜理想介质层建模,用菲涅耳定律仿真自然光的镜面反射,发现在全观测波段相同入射光条件下油膜的反射光存在明显的偏振度(DOP)或偏振角(AOP)光谱偏振可观测性。模型与实际测量结果对比发现:在300~350nm仿真结果和实际测量相符,油膜的反射光偏振性质趋近于油样本;在350~550nm,油膜模型仿真结果比实验的干涉效应更明显,油膜实验数据表明其光谱起偏性质依然与油保持一致;在大于550nm直到近红外波段,实验干涉效应开始显著。说明油膜比油有更强的散射或吸收特性,辨识参数得到油膜的消光系数存在不同于油的随波长先变小后变大的性质。总之,利用光谱椭偏测量方法,通过多波段、多角度测量,分析液体样本的光谱偏振特性和折射率等性质;偏振观测的恰当角度与油/水的布儒斯特角有关,在布鲁斯特角之外的位置观测,油膜的光谱椭偏角相较水都存在分辨能力;对小于200μm的薄油膜近红外波段可重复性较差,而紫外和可见蓝紫波段相比之下有很好的可重复性和区分性,更适合于对甚薄油膜表面种类的遥感观测。该实验涉及的方法可以用于其他油种油膜的偏振光谱测量,实验数据为偏振遥感工作的波段选择与观测角度提供提供参考。

关键词：椭偏测量紫外-可见-近红外偏振光谱特性油膜

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Radar false alarm plots elimination based on multi-feature extraction and classification

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The Journal of China Universities of Posts and Telecommunications 2024年第1期31卷 83-92页

作者： Cheng yi Zhao Yan yin Peiwen School of Control Science and Engineering Tiangong UniversityTianjin 300387China Tianjin Key Laboratory of Intelligent Control of Electrical Equipment Tianjin 300387China

Caused by the environment clutter,the radar false alarm plots are *** false alarm points has always been a key issue in Radar plots *** this paper,a radar false alarm plots elimination method based on multi-feature extraction and classification is proposed to effectively eliminate false alarm ***,the density based spatial clustering of applications with noise(DBSCAN)algorithm is used to cluster the radar echo data processed by constant false-alarm rate(CFAR).The multi-features including the scale features,time domain features and transform domain features are ***,a feature evaluation method combining pearson correlation coefficient(PCC)and entropy weight method(EWM)is proposed to evaluate interrelation among features,effective feature combination sets are selected as inputs of the ***,False alarm plots classified as clutters are *** experimental results show that proposed method can eliminate about 90%false alarm plots with less target loss rate.

关键词： radar plots elimination density based spatial clustering of applications with noise multi-feature extraction classifier

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Scuffing failure analysis based on a multiphysics coupling model and experimental verification

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Friction 2024年第6期12卷 1214-1234页

作者： Bugao LYU Xianghui MENG Jiabao yin yi CUI Chengen WANG School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

General reductions in lubricant viscosities and increasing loads in machine components highlight the role of tribofilms in providing surface protection against ***,the relationship between the scuffing process and the growth and removal of tribofilm is not well *** this study,a multiphysics coupling model,which includes hydrodynamic lubrication,asperity contact,thermal effect,tribochemistry reaction,friction,and surface wear,was developed to capture the initiation of surface *** and experiments for a piston ring and cylinder liner contact were conducted following a step-load sequence under different temperature *** results show that high temperature and extreme load could induce the lubricant film collapse,which in turn triggers the breakdown of the tribofilm due to the significantly increased removal *** failures of both lubricant film and tribofilm progress instantaneously in a coupling way,which finally leads to severe scuffing.

关键词： scuffing failure tribofilm boundary lubrication multiphysics coupling effects

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Alkyl Radical Initiated Cyclization/Cascade for Synthesizing Lactam-Substituted Alkyl Sulfones

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Chinese Journal of Chemistry 2024年第16期42卷 1853-1859页

作者： Li-Jun Wu Kai-yi Zhang Pei Yang Chuan-Chong Peng Jin-Hui Liu Qing Li da-Zhi Sun Shuangfeng yin College of Sciences Central South University of Forestry and TechnologyChangshaHunan410004 China School of Chemistry and Chemical Engineering Inner Mongolia UniversityHohhotInner Mongolia010021 China

An alkyl radical initiated cyclization/tandem reaction of alkyl bromides and alkyl electrophiles by using potassium metabisulphite(K_(2)S_(2)O_(5))as a connector is developed for the synthesis of various lactam-substituted alkyl ***,this process does not require a metal catalyst or metal powder reductant,highlighting its environmentally friendly *** reaction demonstrates outstanding substrate adaptability and a high tolerance towards diverse functional ***,the biologically active molecules and commercially available drugs with a late-stage modification are also highly compatible with this *** studies revealed that the reaction proceeds through a single-step process involving intramolecular radical cyclization,"SO_(2)"insertion,and external alkyl incorporation.

关键词： Alkyl radical Metal-free catalyzed Cyclization/cascade Potassium metabisulphite Electrophiles Alkyl sulfones Lactams Alkyl bromides Sodium formate

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基于增强拉东变换及稀疏先验的模糊星斑复原

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光学精密工程 2018年第6期26卷 1470-1479页

作者：郑天宇尹达一中国科学院红外探测与成像技术重点实验室上海200083 中国科学院上海技术物理研究所上海200083 中国科学院大学北京100049

为了提高动态条件下星光导航系统星斑质心定位精度,本文提出了一种新的模糊星斑复原算法。首先,分析了星斑图像退化模型,得出了星斑质心定位精度与星斑信噪比呈正相关的关系。对于载体角运动和载体振动两个因素引起的模糊星斑复原过程... 详细信息

为了提高动态条件下星光导航系统星斑质心定位精度,本文提出了一种新的模糊星斑复原算法。首先,分析了星斑图像退化模型,得出了星斑质心定位精度与星斑信噪比呈正相关的关系。对于载体角运动和载体振动两个因素引起的模糊星斑复原过程分成粗级复原和精级复原两个步骤。接着分析了噪声对拉东(Radon)变换的影响,提出基于灰度拉伸的改进Radon变换算法进行粗复原。最后,根据清晰星斑的梯度分布稀疏先验正则化,利用迭代盲复原算法对星斑进行精复原。仿真实验结果表明,本文提出的两步模糊星斑复原算法较传统算法复原后星斑峰值信噪比(PSNR)提高30%,质心定位精度提高55%。

关键词：运动模糊星斑复原拉东变换稀疏先验迭代盲复原

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Variations and future projections of glacial discharge of Urumqi River Headwaters,eastern Tien Shan(1980s-2017)

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Advances in Climate Change Research 2024年第3期15卷 537-546页

作者： Hui ZHANG Fei-Teng WANG Ping ZHOU yi-da XIE State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Cryospheric Science and Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

To address data scarcity on long-term glacial discharge and inadequacies in simulating and predicting hydrological processes in the Tien Shan,this study analysed the observed discharge at multiple timescales over 1980se2017 and projected changes within a representative glacierized high-mountain region:eastern Tien Shan,Central *** processes were simulated to predict changes under four future scenarios(SSP1,SSP2,SSP3,and SSP5)using a classical hydrological model coupled with a glacier dynamics *** rates at annual,monthly(June,July,August)and daily timescales were obtained from two hydrological gauges:Urumqi Glacier No.1 hydrological station(UGH)and Zongkong station(ZK).Overall,annual and summer discharge increased significantly(p<0.05)at both stations over the study *** intra-annual variations mainly resulted from differences in their recharge *** simulations show that a tipping point in annual discharge at UGH may occur between 2018 and 2024 under the four SSPs *** discharge is predicted to cease earlier at ZK than at *** relates to glacier type and size,suggesting basins with heavily developed small glaciers will reach peak discharge sooner,resulting in an earlier freshwater supply *** findings serve as a reference for research into glacial runoff in Central Asia and provide a decision-making basis for planning local water-resource projects.

关键词： Observed glacial discharge Temporal variations Urumqi River Headwaters Eastern Tien Shan Simulation and projection

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