检索结果-南通市图书馆

Bioinspired zinc-mediated umpolung thiolation of alkyl electrophiles: reaction development, scope and mechanism

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第3期67卷 898-907页

作者： Yuenian Xu Yan Zhang Yong Liu Wen-Wu sun Jie Huang Hui He Yingjie Wu Wen Liu shao-Fei ni Xu-Qiong Xiao Xinxin shao College of Material Chemistry and Chemical EngineeringKey Laboratory of Organosilicon Chemistry and Material Technology of Ministry of EducationHangzhou Normal UniversityHangzhou 311121China School of Pharmaceutical Sciences South-Central Minzu UniversityWuhan 430074China Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guang-dong Province Shantou UniversityShantou 515063China

Zinc-promoted umpolung thiolation of alkyl electrophiles with masked sulfur transfer reagents in the absence of nickel or copper catalysis is described. This protocol proceeds via a SET process of Zn to electrophilic sulfur reagent followed by insertion of Zn into disulfide and nucleophilic thiolation, providing straightforward access to a wide range of alkyl sulfides with broad substrate scope. A neutral TMEDA-ligated four-coordinated zinc thiolate with tetrahedra geometry was synthesized, isolated and fully characterized by NMR, IR and X-ray analysis. More importantly, the chemical reactivity of this active intermediate has been investigated, enabling the construction of C-Se, C-Te, Sb-S and Bi-S bonds to prepare valuable sulfur-containing molecules and beyond.

关键词： umpolung thiolation C(sp^(3))-S bond formation masked sulfur reagents reductive coupling

同方期刊数据库

在线全文

学校读者我要写书评

暂无评论

激光金属沉积成形基板预热的研究

激光技术 2008年第6期32卷 608-610页

作者：孙少妮东北大学机械工程及自动化学院沈阳110004

为了降低激光金属沉积成形过程中试样和基板间的温度梯度,减小和抑制成形过程的热应力,提高试样的成形质量,提出并设计了一种用于激光金属沉积成形的基板预热系统。该系统由基板预热器、智能比例微分积分控制器以及计算机串口温度采集... 详细信息

为了降低激光金属沉积成形过程中试样和基板间的温度梯度,减小和抑制成形过程的热应力,提高试样的成形质量,提出并设计了一种用于激光金属沉积成形的基板预热系统。该系统由基板预热器、智能比例微分积分控制器以及计算机串口温度采集反馈控制等3部分组成。利用自行研制的激光金属沉积成形设备和基板预热系统进行了成形实验。实验结果表明,基板预热可以改善试样的成形质量,降低成形过程的热应力。

关键词：激光技术激光金属沉积成形基板预热热应力成形质量

Research on an innovative structure of an open-ribbed steel-ultra-high performance concrete composite bridge deck

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2024年第5期18卷 716-730页

作者： Xudong shao Xuan sun Deqiang ZOU Junhui CAO Chuanqi YANG School of Civil Engineering Hunan UniversityKey Laboratory for Wind and Bridge Engineering of Hunan ProvinceChangsha 410082China China Construction Fifth Engineering Division Co. Ltd.Changsha 410004China

To completely solve the problem of fatigue cracking issue of orthotropic steel bridge decks(OSDs),the authors proposed a steel–ultra-high performance concrete(UHPC)lightweight composite deck(LWCD)with closed ribs in *** on the successful application of that LWCD,an adaptation incorporating an innovative composite deck structure,i.e.,the hot-rolled section steel–UHPC composite deck with open ribs(SSD)is proposed in this paper,aiming to simplify the fabrication process as well as to reduce the cost of *** on a long-span cable-stayed bridge,a design scheme is proposed and is compared with the conventional OSD ***,a finite element(FE)calculation is conducted to reflect both the global and local behavior of the SSD scheme,and it is found that the peaked stresses in the SSD components are less than the corresponding allowable values.A static test is performed for an SSD strip specimen to understand the anti-cracking behavior of the UHPC layer under negative bending *** static test results indicate that the UHPC layer exhibited a satisfactory tensile toughness,the UHPC tensile strength obtained from the test is 1.8 times the calculated stress by the FE model of the real *** addition,the fatigue stresses of typical fatigue-prone details in the SSD are calculated and evaluated,and the influences of key design parameters on the fatigue performance of the SSD are *** to the fatigue results,the peaked stress ranges for all of the 10 fatigue-prone details are within the corresponding constant amplitude fatigue *** a fatigue test is carried out for another SSD strip specimen to explore the fatigue behavior of the fillet weld between the longitudinal and transverse *** specimen failed at the fillet weld after equivalent 47.5 million cycles of loading under the design fatigue stress range,indicating that the fatigue performance of the SSD could meet the fatigue design *** calculations and experim

关键词： steel-ultra-high performance concrete composite deck open rib strip model test static and fatigue performance orthotropic steel deck

Eat at the right time: Regulation of ER-phagy receptors in plant response to environmental stresses

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Molecular Plant 2024年第2期17卷 236-239页

作者： Yang shao Jiaqi sun Huanquan Zheng The Key Laboratory of Plant Development and Environmental Adaptation Biology Ministry of EducationSchool of Life SciencesShandong UniversityQingdao 266237China Department of Biology McGill UniversityMontrealQC H3A 1B1Canada

The endoplasmic reticulum(ER)is a cellular factory for biosynthesis of proteins and *** accommodate a wide array of biosynthetic demands in responses to environmental stresses,the plant ER remodels to maintain a structural and functional homeostasis.A key process facilitating this balance is selective autophagy of the ER(ER-phagy),where malfunctioned ER is recognized,engulfed by autophagosomes,and then delivered to the vacuole for degradation.

关键词： maintain accommodate function

Metasurface array for single-shot spectroscopic ellipsometry

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第5期13卷 835-842页

作者： Shun Wen Xinyuan Xue Shuai Wang Yibo ni Liqun sun Yuanmu Yang Department of Precision Instrument State Key Laboratory of Precision Measurement Technology and InstrumentsTsinghua UniversityBeijing 100084China

Spectroscopic ellipsometry is a potent method that is widely adopted for the measurement of thin film thickness and refractive *** conventional ellipsometers utilize mechanically rotating polarizers and grating-based spectrometers for spectropolarimetric ***,we demonstrated a compact metasurface array-based spectroscopic ellipsometry system that allows single-shot spectropolarimetric detection and accurate determination of thin film properties without any mechanical *** silicon-based metasurface array with a highly anisotropic and diverse spectral response is combined with iterative optimization to reconstruct the full Stokes polarization spectrum of the light reflected by the thin film with high ***,the film thickness and refractive index can be determined by fitting the measurement results to a proper material model with high *** approach opens up a new pathway towards a compact and robust spectroscopic ellipsometry system for the high throughput measurement of thin film properties.

关键词： properties. spectroscopic film

Atomically Dispersed Zinc Active Sites Efficiently Promote the Electrochemical Conversion of N_(2) to NH_(3)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy & Environmental Materials 2024年第3期7卷 175-181页

作者： Yanjiao Wei Xinyu Wang Mengjie sun Min Ma Jian Tian Minhua shao School of Materials Science and Engineering Shandong University of Science and TechnologyQingdao 266590China Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong 999077China Energy Institute and Chinese National Engineering Research Center for Control&Treatment of Heavy Metal PollutionThe Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong China

At present,the research on highly active and stable nitrogen reduction reaction catalysts is still challenging work for the electrosynthesis of ammonia(NH_(3)).Herein,we synthesized atomically dispersed zinc active sites supported on N-doped carbon nanosheets(Zn/NC NSs)as an efficient nitrogen reduction reaction catalyst,which achieves a high ammonia yield of 46.62μg h^(-1)mg^(-1)_(cat).at-0.85 V(vs RHE)and Faradaic efficiency of 95.8%at-0.70 V(vs RHE).In addition,Zn/NC NSs present great stability and selectivity,and there is no significant change in NH_(3)rate and Faradaic efficiencies after multiple *** structural characterization shows that the active center in the nitrogen reduction reaction process is the Zn-N_(4)sites in the *** calculation confirms that Zn/NC with Zn-N_(4)configuration has a lower energy barrier for the formation of^(*)NNH intermediate compared with pure N-doped carbon nanosheets(N-C NSs),thus promoting the hydrogenation kinetics in the whole nitrogen reduction reaction process.

关键词： electrocatalysis nitrogen reduction single-atom catalyst Zn-N_(4)

在线全文

学校读者我要写书评

暂无评论

非光滑表面制动盘摩擦磨损性能有限元分析

东北大学学报（自然科学版） 2014年第11期35卷 1597-1601页

作者：孙少妮谢里阳张以忱东北大学机械工程与自动化学院辽宁沈阳110819

基于摩擦试验要求的外形尺寸和非光滑结构的设计尺寸,建立了非光滑表面刹车盘/片模型,通过分析制动过程中接触压力与摩擦热之间的交互作用关系,建立了制动盘/片的热-应力耦合分析模型,并应用Ansys/LS-DYNA对非光滑表面刹车盘/片系统的... 详细信息

基于摩擦试验要求的外形尺寸和非光滑结构的设计尺寸,建立了非光滑表面刹车盘/片模型,通过分析制动过程中接触压力与摩擦热之间的交互作用关系,建立了制动盘/片的热-应力耦合分析模型,并应用Ansys/LS-DYNA对非光滑表面刹车盘/片系统的摩擦磨损性能进行了有限元分析.分析结果表明:当盘孔间距为1 mm,盘孔直径为0.8 mm时,非光滑刹车盘/片试样呈现最小的von Mises应力,为耐磨性最佳的非光滑形态.通过摩擦磨损试验得到与模拟相应试样的磨损量及动摩擦系数,比较后发现二者均体现出与模拟结果中von Mises应力相一致的变化规律,验证了模拟分析结果的可信性.

关键词：非光滑表面摩擦磨损性能热-应力耦合有限元分析

Advanced electrocatalysts with unusual active sites for electrochemical water splitting

在线全文

学校读者我要写书评

暂无评论

InfoMat 2024年第1期6卷 65-82页

作者： Hainan sun Xiaomin Xu Hyunseung Kim Zongping shao WooChul Jung Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology(KAIST)DaejeonRepublic of Korea WA School of Mines:Minerals Energy and Chemical Engineering(WASM-MECE) Curtin UniversityPerthWestern AustraliaAustralia

Electrochemical water splitting represents a promising technology for green hydrogen *** design advanced electrocatalysts,it is crucial to identify their active sites and interpret the relationship between their structures and *** extensively studied as electrocatalysts include noble-metal-based(e.g.,Ru,Ir,and Pt)and non-noble-metal-based(e.g.,3d transition metals)***,advancements in characterization techniques and theoretical calculations have revealed novel and unusual active *** present review highlights the latest achievements in the discovery and identification of various unconventional active sites for electrochemical water splitting,with a focus on state-of-the-art strategies for determining true active sites and establishing structure–activity ***,we discuss the remaining challenges and future perspectives for the development of next-generation electrocatalysts with unusual active *** presenting a fresh perspective on the unconventional reaction sites involved in electrochemical water splitting,this review aims to provide valuable guidance for the future study of electrocatalysts in industrial applications.

关键词： electrochemical water splitting hydrogen evolution reaction oxygen evolution reaction structure–activity relationship unusual active sites

Role of adaptation measures in addressing heatwave exposure in China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Climate Change Research 2024年第1期15卷 148-157页

作者： Qin-Mei HAN Qing-Chen CHAO shao sun Pei-Jun SHI National Climate Centre China Meteorological AdministrationBeijing 100081China State Key Laboratoryof Severe Weather Chinese Academy of Meteorological Sciences Beijing 0o08lChina Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China

Heatwave exposure has increased dramatically because of climate warming and population growth,along with their interactive ***,effective adaptation measures can reduce these ***,the dynamic changes,regional inequality in adaptive capacity and their potential contributions to reducing exposure in the future remain *** study quantifies the impact of adaptive capacity and underscores regional variations in heatwave magnitudes,population exposure and adaptation levels in *** projected the future adaptive capacity using air-conditioner penetration,factoring in climate cooling requirements and individuals'purchasing *** population and gross domestic product(GDP)data from four Shared Socioeconomic Pathways(SSP1,SSP2,SSP3 and SSP5)and daily temperature data from four SSP-based emission scenarios(SSP1-2.6,SSP2-4.5,SSP3-7.0 and SSP5-8.5),we estimated heatwave duration,population exposure and avoided impacts through adaptation across China and its *** show a substantial increase in heatwave duration in Southwest and Southern China,especially under the SSP5-8.5 scenario,with a projection of 163.2±36.7 d during *** the SSP3|SSP3-7.0 scenario,total exposure reaches 156.4±76.8 billion person d per year,which is the highest among all scenarios and 23 times greater than that in 1986-2005 without *** considering adaptation measures,a noteworthy reduction in population exposure is observed,especially in the SSP3|SSP3-7.0 and SSP5JSSP5-8.5 scenarios,with reductions of(62.6±3.9)%and(65.8±5.1)%,respectively,compared with the scenario without adaptation during *** regional disparities in avoided impacts are also evident,with variations of up to 50%across different *** implementation of effective and environmentally friendly adaptation measures can notably address climate change,thereby alleviating the profound threats posed to human well-being.

关键词： Heatwaves Population exposure Adaptation Future projection China