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Highly efficient tunable photodetector with a bipolar response in van der Waals heterojunctions

Science China(Technological Sciences) 2024年第2期67卷 639-646页

作者： SHI ChaoFan ZHANG Shi XIAO KeNing ZHANG LiBo HAN Li ZHU YuLin TANG WeiWei LIU ChangLong LI GuanHai chen xiaoshuang College of Physics and Optoelectronic Engineering Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences Hangzhou310024China State Key Laboratory of Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083China

The heterojunction integration of two-dimensional(2D)materials via van der Waals(vdW)forces,unencumbered by lattice and processing constraints,constitutes an efficacious approach to enhance the overall optoelectronic performance of photodetectors,due to an assortment of distinctive light-matter ***,vdW heterojunction photodetectors based on transition metal dichalcogenides(TMDs)face an inevitable trade-off between low dark currents and high responsivity,curtailing the application potential of myriad novel optoelectronic components in sensing,spectral,and communication *** this study,we present the successful actualization of a highly sensitive,self-powered,and gate-tunable bipolar response *** mechanisms underlying photocurrent generation were scrutinized via bias-,power-,and position-dependent mapping photoresponse measurements,identifying the photovoltaic effect,which is attributable to the Schottky junction’s built-in electric field,as the predominant *** prototype Au-WS2-graphene photodetector exhibits a remarkable light on/off ratio of 1.2×10^(6),a specific detectivity of 6.12×10^(11)cm H^(z1/2)W^(-1)with 20μs response time at 638 *** wide gate-tunable responsivity provides an adjustability scope,ranging from 0.9 to 3.1 A W^(-1).Notably,the device demonstrates an exceptional linear photocurrent response,with a linear dynamic range(LDR)value approximating 130 dB,which significantly surpasses that of other photodetectors based on TMDs.

关键词： WS2/graphene van der Waals heterojunction gate-tunable bipolar response

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快速康复护理在胃肠道手术患者围术期护理中的应用效果

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临床研究 2024年第2期32卷 188-191页

作者：肖娜丽陈小爽河南大学第一附属医院消化病联合微创病区河南开封475000

目的探讨快速康复护理在胃肠道手术患者围术期护理中的应用效果。方法选择河南大学第一附属医院2021年5月至2023年5月期间收治的50例胃肠道手术患者,通过随机抽签法进行分组,两组各25例。对照组实施围术期常规护理,观察组在此基础上实... 详细信息

目的探讨快速康复护理在胃肠道手术患者围术期护理中的应用效果。方法选择河南大学第一附属医院2021年5月至2023年5月期间收治的50例胃肠道手术患者,通过随机抽签法进行分组,两组各25例。对照组实施围术期常规护理,观察组在此基础上实施快速康复护理,比较两组各项临床指标、疼痛情况、术后并发症和护理满意率。结果两组术中出血量和手术时间比较,差异无统计学意义(P>0.05);观察组首次肛门排气、首次下床活动、恢复普食时间和住院天数短于对照组,差异有统计学意义(P<0.05);观察组术后6 h、术后24 h、术后48 h和术后72 h疼痛数字评分法(NRS)评分低于对照组,差异有统计学意义(P<0.05);观察组术后并发症发生率(4.00%)低于对照组(24.00%),差异有统计学意义(P<0.05);观察组护理满意率(100.00%)高于对照组(84.00%),差异有统计学意义(P<0.05)。结论快速康复护理用于胃肠道手术患者围术期护理中能缩短首次肛门排气时间、恢复普食时间、首次下床活动时间和住院天数,减轻术后疼痛程度,减少并发症发生,并提高护理满意率,值得应用。

关键词：胃肠道手术围术期护理快速康复护理

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公立医院手术专科运营评价体系构建及应用

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中国卫生经济 2024年第3期43卷 65-67页

作者：陈晓双周倩琳费凡张咏史新亮曹瑾音中山大学附属第一医院广州510080

采用文献分析、专家咨询、案例分析等方法,构建适应高质量发展的公立医院专科运营评价体系,包括医疗能力和经济运营两类一级指标和13个二级指标,并以案例医院泌尿外科为例开展了手术专科运营效果评价。文章认为,加强公立医院专科运营评... 详细信息

采用文献分析、专家咨询、案例分析等方法,构建适应高质量发展的公立医院专科运营评价体系,包括医疗能力和经济运营两类一级指标和13个二级指标,并以案例医院泌尿外科为例开展了手术专科运营效果评价。文章认为,加强公立医院专科运营评价,应注重医疗能力评价,强化职能部门协作,完善运营配套政策等措施,并以此推动医院高质量运营发展。

关键词：公立医院手术专科运营评价

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The spatial-temporal pattern and influencing factors of negative air ions in urban forests, Shanghai, China

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Journal of Forestry Research 2014年第4期25卷 847-856页

作者： Hong Liang xiaoshuang chen Junguang Yin Liangjun Da Department of Environmental Science East China Normal University Tiantong Forest Ecosystem National Research Station and Shanghai Key Laboratory for Ecology of Urbanization Process and Eco-restoration College of Landscape Architecture and Forestry Qingdao Agricultural University Kunshan Municipal Environmental Protection Bureau

Negative air ions are natural components of the air we breathe Forests are the main continuous natural source of negative air ions （NAI）. The spatio-temporal patterns of negative air ions were explored in Shanghai, based on monthly monitoring in 15 parks from March 2009 to February 2010. In each park, sampling sites were selected in forests and open spaces. The annual variation in negative air ion concentrations （NAIC） showed peak values from June to October and minimum values from December to January. NAIC were highest in summer and autumn, intermediate in spring, and lowest in winter. During spring and summer, NAIC in open spaces were significantly higher in rural areas than those in suburban areas. However, there were no significant differences in NAIC at forest sites among seasons. For open spaces, total suspended particles （TSP） were the dominant determining factor of NAIC in sum- mer, and air temperature and air humidity were the dominant determining factors of NAIC in spring, which were tightly correlated with Shanghai＇s ongoing urbanization and its impacts on the environment. R is suggested that urbanization could induce variation in NAIC along the urban-rural gradient, but that may not change the temporal variation pattern. Fur- thermore, the effects of urbanization on NAIC were limited in non-vegetated or less-vegetated sites, such as open spaces, but not in well-vegetated areas, such as urban forests. Therefore, we suggest that urban greening, especially urban forest, has significant resistance to theeffect of urbanization on NAIC.

关键词： negative air ion concentration spatial-temporal pattern urbanization urban ecosystem urban greening

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Chaiqin chengqi decoction inhibits inflammatory mediators and attenuates acute pancreatitis through deactivation of janus kinase/signal transducer and activator of transcription signaling pathway

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Journal of Traditional Chinese Medicine 2019年第2期39卷 166-173页

作者： Dong Jianxia chen xiaoshuang Song Yi Fei Xiaofan Department of Clinical Pharmacy West China Hospital of Sichuan University

OBJECTIVE: To investigate the effect of Chaiqin chengqi decoction(CQCQD) on acute pancreatitis(AP) by janus kinase/signal transducer and activator of transcription(JAK/STAT) signaling pathway in vitro and in ***: AP was induced by caerulein both in AR42J cells and in mice. AR42J cells were divided into five groups: the control group, the AP group, the CQCQD group, JAK/STAT signaling pathway inhibitor AG490 group, and the CQCQD and AG490 *** induction, cellular supernatant of five groups were collected for measuring the concentrations of inflammatory cytokine amylase, interleukin 6(IL-6),tumor necrosis factor α(TNF-α), interleukin 1β(IL-1β), nuclear factor κB(NF-κB) by enzyme-linked immunosorbent assay and the expression of JAK-2,STAT-3 signaling transduction proteins by Western blot, respectively. Experiments in mice were performed similar to that of in AR42J ***: Treatment of AR42J cells with CQCQD reduced the pancreatic injury and negatively regulated the activities of amylase, as well as inhibited expression of several inflammatory cytokines such as IL-6, TNF-α, IL-1β, NF-κB. Administration of CQCQD significantly inhibited JAK-2 activation and down-regulated phosphorylation of downstream substrate STAT-3 the same as AG490, resulting in inhibition of inflammatory mediators and amelioration of ***: The results suggested that CQCQD exerted anti-inflammatory effects on AP via reducing expression and phosphorylation of JAK and STAT.

关键词： Pancreatic diseases Anti-inflammatory agents Janus kinase 2 STAT transcription factors Chaiqin chengqi decoction

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Stochastic processes in renewable power systems: From frequency domain to time domain

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Science China(Technological Sciences) 2019年第12期62卷 2093-2103页

作者： SONG YongHua chen xiaoshuang LIN Jin LIU Feng QIU YiWei Department of Electrical and Computer Engineering University of MacaoMacaoChina State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

With the increasing penetration of renewable energy resources(RESs), the uncertainties of volatile renewable generations significantly affect the power system operation. Such uncertainties are usually modeled as stochastic variables obeying specific distributions by neglecting the temporal correlations. Conventional approaches to hedge the negative effects caused by such uncertainties are thus hard to pursue a trade-off between computation efficiency and optimality. As an alternative, the theory of stochastic process can naturally model temporal correlation in closed forms. Attracted by this feature, our research group has been conducting thorough researches in the past decade to introduce stochastic processes within renewable power systems. This paper summarizes our works from the perspective of both the frequency domain and the time domain, provides the tools for the analysis and control of power systems under a unified framework of stochastic processes, and discusses the underlying reasons that stochastic process-based approaches can perform better than conventional approaches on both computational efficiency and optimality. These work may shed a new light on the research of analysis, control and operation of renewable power ***, this paper outlooks the theoretic developments of stochastic processes in future’s renewable power systems.

关键词： renewable energy resources renewable power systems stochastic processes frequency domain time domain

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镉污染红黏土电阻率特性及其评价模型研究

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中国农业科技导报 2024年第4期26卷 164-173页

作者：陈小双徐兴倩赵熹屈新王海军彭光灿云南农业大学水利学院昆明 650201 安阳工学院土木与建筑工程学院河南安阳 455000

为探究重金属污染物镉对红黏土电阻率特性的影响特征,制备不同含水率、干密度、镉含量的红黏土试样,采用二极法进行电阻率测试,分析不同因素与红黏土电阻率的关系,建立镉污染红黏土电阻率评价模型.结果表明,镉污染红黏土电阻率随着干密... 详细信息

为探究重金属污染物镉对红黏土电阻率特性的影响特征,制备不同含水率、干密度、镉含量的红黏土试样,采用二极法进行电阻率测试,分析不同因素与红黏土电阻率的关系,建立镉污染红黏土电阻率评价模型.结果表明,镉污染红黏土电阻率随着干密度、含水率和温度的增加均呈下降趋势,干密度小于1.30 g·cm-3范围内电阻率急剧下降,随后电阻率逐渐减小并趋于稳定;在不同镉含量条件下随着含水率增加电阻率逐渐减小,在干密度为1.20 g·cm-3时电阻率下降最显著;在干密度、含水率相同条件下,0℃以上温度变化对电阻率的影响不明显,镉溶液掺入量增加导致电阻率逐渐减小,当镉含量小于100 mg·kg-1时电阻率变化幅度较大.综合考虑电阻率随干密度、含水率和温度变化特征,引入体积含水量建立镉污染红黏土电阻率评价模型,拟合精度较高(R2=0.939 9),实测值与模型值较吻合,平均绝对百分比误差和均方根误差分别为4.77%、0.07.该模型可为红黏土地区重金属镉污染度的电法快速检测提供理论模型参考,为区域性红黏土耕地质量评价提供便捷分析手段.

关键词：红黏土镉污染影响因素电阻率模型

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镉污染红黏土强度劣化机理分析

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农业环境科学学报 2024年第7期43卷 1503-1511页

作者：陈小双徐兴倩刘剑赵熹尹亚敏王海军王能龙云南农业大学水利学院昆明 650201 河北工程大学地球科学与工程学院河北邯郸 056038

为探究镉污染条件下红黏土的微观结构演化对土体抗剪强度的影响,揭示镉污染红黏土的强度劣化机理,本研究通过直剪试验、X射线衍射(XRD)分析和扫描电子显微镜(SEM)观察研究了镉污染红黏土的剪切特性和微观结构特征.结果表明:随着镉含量... 详细信息

为探究镉污染条件下红黏土的微观结构演化对土体抗剪强度的影响,揭示镉污染红黏土的强度劣化机理,本研究通过直剪试验、X射线衍射(XRD)分析和扫描电子显微镜(SEM)观察研究了镉污染红黏土的剪切特性和微观结构特征.结果表明:随着镉含量的增加,黏聚力平均减小25.5%,内摩擦角平均增大21.1%,抗剪强度出现劣化趋势,剪切破坏面形态凹凸越来越明显;微观影像显示出颗粒蚀化现象,孔隙发育平均增大11.8%,且呈蜂窝状,土颗粒接触方式由角-面、边-面、面-面转为角-边、点-面接触,微观结构指标(颗粒丰度、定向频率及孔隙分形维数)反映出土颗粒由强联结转化为弱接触的变化特征;因黏土颗粒对镉离子吸附能力较强,导致扩散双电层被压缩,同时镉离子与黏土中碳酸盐类发生水解反应,从而降低了黏土颗粒间结合水膜连结力,黏聚结构功能逐渐弱化.研究表明,镉污染对红黏土抗剪强度产生劣化效应,在地表径流冲刷作用下易加剧耕地层水土流失等危害.

关键词：红黏土镉污染抗剪强度微观结构劣化效应

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Reversible doping polarity and ultrahigh carrier density in two-dimensional van der Waals ferroelectric heterostructures

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Frontiers of physics 2023年第3期18卷 91-102页

作者： Yanyan Li Mingjun Yang Yanan Lu Dan Cao xiaoshuang chen Haibo Shu College of Optical and Electronic Technology China Jiliang UniversityHangzhou 310018China College of Science China Jiliang UniversityHangzhou 310018China National Laboratory for Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of ScienceShanghai 200083China

Van der Waals semiconductor heterostructures(VSHs)composed of two or more two-dimensional(2D)materials with different band gaps exhibit huge potential for exploiting high-performance multifunctional *** application of 2D VSHs in atomically thin devices highly depends on the control of their carrier type and ***,on the basis of comprehensive first-principles calculations,we report a new strategy to manipulate the doping polarity and carrier density in a class of 2D VSHs consisting of atomically thin transition metal dichalcogenides(TMDs)andα-In_(2)X_(3)(X=S,Se)ferroelectrics via switchable polarization *** calculated results indicate that the band bending of In_(2)X_(3)layer driven by the FE polarization can be utilized for engineering the band alignment and doping polarity of TMD/In_(2)X_(3)VSHs,which enables us to control their carrier density and type of the VSHs by the orientation and magnitude of local FE polarization *** by these findings,we demonstrate that doping-free p–n junctions achieved in MoTe2/In2Se3 VSHs exhibit high carrier density(1013–1014 cm–2),and the inversion of the VHSs from n–p junctions to p–i–n junctions has been realized by the polarization switching from upward to downward *** work provides a nonvolatile and nondestructive doping strategy for obtaining programmable p–n van der Waals(vdW)junctions and opens the possibilities for self-powered and multifunctional device applications.

关键词： van der Waals heterostructures ferroelectric polarization carrier type band alignment density-functional theory

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Optical property of amorphous semiconductor mercury cadmium telluride from first-principles study

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Science China(Technological Sciences) 2009年第7期52卷 1928-1932页

作者： WANG Liang chen xiaoshuang LU Wei HUANG Yan WANG XiaoFang ZHAO JiJun National Laboratory for Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083China State Key Laboratory of Materials Modification by Laser Electronand Ion BeamsSchool of Physics and Optoelectronic Technology and College of Advanced Science and TechnologyDalian University of TechnologyDalian 116024China

The structural and optical properties of amorphous semiconductor mercury cadmium telluride (a-MCT) are obtained by the first principles calculations. The total pair distribution functions and the density of states show that the a-MCT has the semiconductor characteristic. The calculated results of dielectric function show that E2 peak of the imaginary of dielectric function for the crystal mercury cadmium telluride abruptly disappears in the amorphous case due to the long-range disorders. And the imaginary of dielectric function of a-MCT shows a large broad peak, which is in agreement with the available results of other amorphous semiconductors. From the linear extrapolation of the curve ωε 2(ω)1/2 versus ω, it can be obtained that the optical energy gap of amorphous semiconductor Hg0.5Cd0.5Te is 0.51±0.05 eV.

关键词： first-principles calculations optical property dielectric function absorption coefficient

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