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Influence of carrier concentration on the resistive switching characteristics of a ZnO-based memristor

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Nano Research 2016年第4期9卷 1116-1124页

作者： Yihui sun Xiaoqin Yan Xin Zheng yichong Liu Yanwei Shen Yue Zhang State Key Laboratory for Advanced Metals and Materials School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Beijing Municipal Key Laboratory of New Energy Materials and Technologies University of Science and Technology Beijing Beijing 100083 China

Sandwich-style memristor devices were synthesized by electrochemical deposition with a ZnO film serving as the active layer between Al-doped ZnO （AZO） and Au electrodes. The carrier concentration of the ZnO films is controlled by adding HNO3 during the growth process. A resulting increase in carrier concentration from 10^17 to 10^19 cm^-3 was observed, along with a corresponding drop in the on--off ratio from 6,437% to 100%. The resistive switching characteristics completely disappeared when the carrier concentration was above 1029 cm-3, making it unsuitable for a memory device. The decreasing switching ratio is attributed to a reduction in the driving force for oxygen vacancy drift. Systematic analysis of the migration of oxygen vacancies is presented, including the concentration gradient and electrical potential gradient. Such oxygen vacancy migration dynamics provide insight into the mechanisms of the oxygen vacancy drift and provide valuable information for industrial production of memristor devices.

关键词： resistive switch,carrier concentration,driving force,potential gradient,concentration gradient

基于网络点评数据的城市公园公众满意度及其影响因素研究

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地域研究与开发 2021年第4期40卷 63-68页

作者：刘瑞雪孙毅翀深圳大学建筑与城市规划学院广东深圳518060

城市公园是公众进行户外休闲游憩活动的主要场所。营造能激发公众参与意愿、与公众需求相匹配的城市公园,既是当前城市建设亟待解决的问题,也是公众的普遍诉求。以深圳城市综合公园为例,通过收集网络主流点评网站的图文评价信息,利用词... 详细信息

城市公园是公众进行户外休闲游憩活动的主要场所。营造能激发公众参与意愿、与公众需求相匹配的城市公园,既是当前城市建设亟待解决的问题,也是公众的普遍诉求。以深圳城市综合公园为例,通过收集网络主流点评网站的图文评价信息,利用词频分析法提炼公众对城市公园规划设计与运行管理相关的关注点,构建城市公园公众体验评价指标体系。采用语义分析法解析评论信息,对评价指标定量化赋值,通过主成分分析和多元回归确定影响公众满意度的城市公园规划设计与运行管理关键因素。结果表明:网络点评数据能够反映公众对城市公园的使用体验和满意度,但在空间分布上呈现明显不均衡;公众对公园的景观效果、生态环境以及是否适合运动健身活动较为看重;到达交通、外部景观效果、植物长势、游人数量、活动类型丰富度、主题活动均会对公众满意度有较大影响。研究结果可为城市公园的规划设计优化与运行管理水平提升提供科学的决策依据。

关键词：城市公园网络点评数据评价体系语义分析公众满意度

A two-branch tradeoff neural network for automatic sleep stage scoring

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A two-branch tradeoff neural network for automatic sleep sta...

Effect of carrier screening on ZnO-based resistive switching memory devices

中国睡眠研究会第十四届全国学术年会

作者： Di Zhang Jinbo sun yichong She Wei Qin Xidian University

Background and Objective: Based on big data and artificial intelligence development, deep learning models for automatic sleep stage scoring that exceeds human scores’ agreement have been proposed in past research. Nevertheless, algorithms still suffer from the performance of stage N1. We aim to propose a new deep learning model to make its training process more suitable for the particular task of sleep staging, to achieve more robust performance in terms of stage N1 and overall scoring. Method: An end-to-end network model was implemented for sleep staging. This network consisted of two parts: a CNN composed of 1 d attention residual block for feature extraction, a classifier that could not only consider single epoch features but also look back and forward through consecutive epochs. Stage N1 accounts for a small proportion of all-night sleep and has confusing features, often relying on context to recognize. We proposed a novel transitive training strategy to minimize the impact from rebalancing N1 on overall performance. According to the training process, a decreasing factor α is automatically generated in the training phase, and the classification loss is calculated by adding two branche loss separately after alpha modulation. It means that the model can first train universal patterns with less influence by weak characteristics, and then exhaustively improve the performance of minority class(like N1) under these universal patterns and sequential information from context. Model with proposed transitive training strategy can effectively balance the intra-epoch and inter-epoch features in the sleep stage division, thus minimizing the performance cost when rebalancing the N1 stage. This model inputs five PSG channels of EEG(C3, C4), EOG(L, R), EMG and uses a five-to-one way to predict an epoch’s sleep stage. Result: A large-scale publicly available dataset with 5793 subjects, SHHS, was used for model training and test. The fitted model achieved accuracy of 88.16%, Cohen’s kappa of 0.836, and MF1 score of 0.818, and

关键词： sleep staging deep learning convolutional neural network N1 sleep rebalancing

来源： cnki会议评论

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Nano Research 2017年第1期10卷 77-86页

作者： Yihui sun Xiaoqin Yan Xin Zheng Yong Li yichong Liu Yanwei Shen Yi Ding Yue Zhang State Key Laboratory for Advanced Metals and Materials School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Beijing Municipal Key Laboratory of New Energy Materials and Technologies University of Science and Technology Beijing Beijing 100083 China

The carrier screening effect occurs commonly in dielectric materials. It reduces the electric potential gradient, thus negatively affecting the functionality of resistive random access memory （RRAM） devices. An Au/ZnO film/Al-doped ZnO device fabricated in this work exhibited no resistive switching （RS）, which was attributed to the carrier screening effect. Therefore, annealing was used for alleviating the screening effect, significantly enhancing the RS property. In addition, different on/off ratios were obtained for various bias values, and the screening effect was accounted for by investigating electron transport mechanisms. Furthermore, different annealing temperatures were employed to modulate the free carrier concentration in ZnO films to alleviate the screening effect. The maximal on/off ratio reached 10s at an annealing temperature of 600 ℃, yielding the lowest number of free carriers and the weakest screening effect in ZnO films. This work investigates the screening effect in RS devices. The screening effect not only modulates the characteristics of memory devices but also provides insight into the mechanism of RS in these devices.

关键词： resistive switch,carrier screening effect,carrier concentration,potential gradient,annealing

Design of sandwich-structured ZnO/ZnS/Au photoanode for enhanced efficiency of photoelectrochemical wate splitting

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Nano Research 2015年第9期8卷 2891-2900页

作者： yichong Liu Yousong Gu Xiaoqin Yan Zhuo Kang Shengnan Lu Yihui sun Yue Zhang State Key Laboratory for Advanced Metals and Materials School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Key Laboratory of New Energy Materials and Technologies University of Science and Technology Beijing Beijing 100083 China

We developed and demonstrated a ZnO/ZnS/Au composite photoanode with significantly enhanced photoelectrochemical water-splitting performance, con- taining a ZnS interlayer and Au nanoparticles. The solar-to-hydrogen conversion efficiency of this ZnO/ZnS/Au heterostructure reached 0.21%, 3.5 times that of pristine ZnO. The comparison of the incident photon-to-current efficiency （IPCE） and the photoresponse in the white and visible light regions further verified that the enhancement resulted from contributions of both UV and visible light. The modification of the Au NPs was shown to improve the photoelectrochemical （PEC） performance to both UV and visible light, as modification encouraged effective surface passivation and surface-plasmon- resonance effects. The ZnS interlayer favored the movement of photogenerated electrons under UV light and hot electrons under visible light, causing their injection into ZnO; this simultaneously suppressed the electron-hole recombination at the photoanode-electrolyte interface. The optimized design of the interlayer within plasmonic metal/semiconductor composite systems, as reported here, provided a facile and compatible photoelectrode configuration, enhancing the utilization efficiency of incident light for photoelectrochemical applications.

关键词： ZnO,ZnS,Au,photoanode,photoelectrochemicalwater splitting

Diversity,community structure,and quantity of eukaryotic phytoplankton revealed using 18S rRNA and plastid 16S rRNA genes and pigment markers:a case study of the Pearl River Estuary

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Marine Life Science & Technology 2023年第3期5卷 415-430页

作者： Shumin Xu Guihao Li Cui He Yi Huang Dan Yu Huiwen Deng Zhuyin Tong yichong Wang Christine Dupuy Bangqin Huang Zhuo Shen Jie Xu Jun Gong School of Marine Sciences Sun Yat-Sen University(Zhuhai Campus)and Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519000China Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering Guangzhou 510006China State Key Laboratory of Marine Environmental Science Xiamen UniversityXiamen 361102China BIOFEEL UMRi LIENSsLa Rochelle Université/CNRSLa RochelleFrance Centre for Regional Oceans Department of Civil and Environmental EngineeringFaculty of Science and TechnologyUniversity of MacaoMacaoChina

Understanding consistencies and discrepancies in characterizing diversity and quantity of phytoplankton is essential for better modeling ecosystem change.In this study,eukaryotic phytoplankton in the Pearl River Estuary,South China Sea were investigated using nuclear 18S rRNA and plastid 16S or 23S rRNA genes and pigment analysis.It was found that 18S abundance poorly explained the variations in total chlorophyll a(Chl-a).However,the ratios of log-transformed 18S abundance to Chl-a in the major phytoplankton groups were generally environment dependent,suggesting that the ratio has potential as an indicator of the physiological state of phytoplankton.The richness of 18S-based operational taxonomic units was positively correlated with the richness of 16S-based amplicon sequence variants of the whole phytoplankton community,but insignifcant or weak for individual phytoplankton groups.Overall,the 18S based,rather than the 16S based,community structure had a greater similarity to pigment-based estimations.Relative to the pigment data,the proportion of haptophytes in the 18S dataset,and diatoms and cryptophytes in the 16S dataset,were underestimated.This study highlights that 18S metabarcoding tends to refect biomass-based community organization of eukaryotic phytoplankton.Because there were lower copy numbers of plastid 16S than 18S per genome,metabarcoding of 16S probably approximates cell abundance-based community organization.Changes in biomass organization of the pigment-based community were sensitive to environmental changes.Taken together,multiple methodologies are recommended to be applied to more accurately profle the diversity and community composition of phytoplankton in natural ecosystems.

关键词： Accessory pigments Chloroplast Marker gene Metabarcoding Phytoplankton

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LEF1基因在鹅胚胎期皮肤毛囊中的表达

吉林农业大学学报 2024年第2期46卷 324-328页

作者：孙越刘静刘畅王义冲周宇轩隋玉健孙永峰吉林农业大学动物科学技术学院长春130118

为了解LEF1基因在鹅胚胎期皮肤毛囊发育过程中的作用,以胚胎期12,18,28 d的吉林白鹅和胚胎期13,18,28 d的卡洛斯鹅为试验动物。利用苏木精-伊红染色法(HE染色)对皮肤组织进行组织形态学观察,采用荧光定量PCR对LEF1基因在胚胎期鹅背部皮... 详细信息

为了解LEF1基因在鹅胚胎期皮肤毛囊发育过程中的作用,以胚胎期12,18,28 d的吉林白鹅和胚胎期13,18,28 d的卡洛斯鹅为试验动物。利用苏木精-伊红染色法(HE染色)对皮肤组织进行组织形态学观察,采用荧光定量PCR对LEF1基因在胚胎期鹅背部皮肤毛囊中的相对表达量进行检测及分析。结果表明:胚胎期为鹅初级毛囊的原始发育期,卡洛斯鹅胚胎期毛囊发育快于吉林白鹅;LEF1基因在胚胎期吉林白鹅及卡洛斯鹅的毛囊中均有表达,表达量在18 d时为高峰期。说明LEF1基因可能在胚胎期吉林白鹅及卡洛斯鹅的毛囊发育过程中发挥一定的作用。

关键词： LEF1 吉林白鹅卡洛斯鹅皮肤毛囊

Spike waves and synaptic ultrastructure in human epileptic brains

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CHINESE MEDICAL JOURNAL 1996年第5期109卷 389-392页

作者： Li Guilin Tan Yuling Wang yichong Bai Qin Xu Yulun sun Yilin Qu Baoqing BeijingNeurosurgicalInstitute TiantanHospitalBeijing NeurosurgeryDepartment TiantanHospitalBeijing

OBJECTIVE To find morphological changes of synapses related to the spike discharge by observation on ultrastructures of the EEG spike foci of cerebral cortexes.MATERIAL AND METHODS The cerebral cortexes were obtained surgically from the EEG spike (recorded by flaky silver electrodes on the surface of cortexes) foci and nonspike areas within the limits of the brain tissue that would be removed in 20 cases of human epilepsy, and were processed for transmission electron microscopic (TEM) observation.RESULTS In the spike foci, presynaptic terminals of axospinal asymmetric synapses were obviously swollen but postsynaptic spines were relatively unaffected. In these synapses, the synaptic vesicles remarkably decreased in number and accumulated predominantly at the presynaptic membranes or aggregated. Similar changes were observed in the presynaptic terminals of the axospinal asymmetric synapses in the nonspike areas but were of milder degree than in the spike foci.CONCLUSIONS Axospinal asymmetric synapses may release a large quantity of excitatory neurotransmitters, which may result in epileptic abnormal electric activities during seizure.

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压电驱动三自由度柔顺精密定位平台研究

振动．测试与诊断 2019年第1期39卷 176-183,229页

作者：张泉东益冲任广孙翊彭艳蒲华燕李小毛上海大学机电工程与自动化学院上海200072 广州大学机械与电气工程学院广州510006

设计了一种由压电陶瓷驱动的整体式平面3-PRR柔顺并联定位平台,平台每条支链采用半圆型柔性转动铰链和直角型柔性直线铰链代替传统的转动副和移动副,消除了传统机构的铰链配合间隙和摩擦,通过Ansys软件对两种铰链进行了刚度分析,并在支... 详细信息

设计了一种由压电陶瓷驱动的整体式平面3-PRR柔顺并联定位平台,平台每条支链采用半圆型柔性转动铰链和直角型柔性直线铰链代替传统的转动副和移动副,消除了传统机构的铰链配合间隙和摩擦,通过Ansys软件对两种铰链进行了刚度分析,并在支链的输入端设计了柔性杠杆位移放大机构以提高平台的工作空间。基于"伪刚体模型法"建立了柔顺定位平台的运动学模型,采用Ansys软件对柔顺并联平台进行有限元分析,得到其静力学特性,最后搭建了平台测试实验系统进行了验证实验。通过运动学模型解析结果和有限元仿真结果与实验结果对比,得到在x方向、y方向和转动角φp的最大误差分别为10.81%,9.66%和9.79%,验证了运动学理论模型建模方法的可行性。

关键词：精密定位平台伪刚体模型压电陶瓷柔性铰链