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CCS Chemistry 2023年第9期5卷 2023-2032页

作者： Xuan dai Fuhao Zhang Lei Dai Yixin Lu Department of Chemistry National University of SingaporeSingapore 117543 School of Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094

Asymmetric dearomatization reactions of various electron-deficient heteroarenes,including benzofurans,benzothiophenes,and indoles,have been described.Through a phosphine-catalyzed[3+2]annulation with vinylcyclopropanes,readily available heteroarene feedstocks undergo smooth dearomatization reactions,delivering a diverse array of valuable chiral cyclopentabenzodihydrofuran and cyclopentaindoline scaffolds in a highly diastero-and enantioselective manner.Notably,the employment of cyclopropanes in phosphine-mediated annulation for the dearomatization of electron-deficient arenes is unknown.

关键词： dearomatization enantioselectivity phosphine catalysis electron-deficient heteroarenes vinylcyclopropanes

Recent advances in N-heterocyclic carbene-catalyzed radical reactions

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Chinese Chemical Letters 2021年第2期32卷 660-667页

作者： Lei Dai Song Ye Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Molecular Recognition and Function.CAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Bejing 100049China

The N-heterocyclic carbene(NHC)-catalyzed reactions involving two-electron reaction pathway have been well-established.However,the development of NHC-catalyzed radical reactions is still in its infancy in terms of reaction types and enantioselectivity.In the past decade,several elegant NHC-catalyzed radical reactions have been developed,including NHC-catalyzed oxidation of aldehydes to esters,reductive coupling reactions using Breslow intermediate as SET reductant and NHC-catalyzed reactions via radical homoenolates,dienoaltes and trienolates.This review summarizes the recent advances in NHC-catalyzed reactions involving radical intermediates.

关键词： N-Heterocyclic carbene Radical Photocatalysis Organocatalysis SET

Reduction of unactivated alkyl chlorides enabled by light-induced single electron transfer

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Science China Chemistry 2024年第2期67卷 471-481页

作者： Lei Dai Zhao-Fei Zhang Xiang-Yu Chen School of Chemical Sciences University of the Chinese Academy of SciencesBeijing100049China Institute of Chemistry Chinese Academy of SciencesBeijing100190China Binzhou Institute of Technology Weiqiao-UCAS Science and Technology ParkBinzhou256606China

Alkyl chlorides are abundant and easily accessible starting materials.However,due to the high reduction potentials associated with unactivated alkyl chlorides,achieving their single electron reduction remains a persistent challenge.This challenge has spurred the exploration of efficient activation methods to overcome this issue.In recent years,photocatalysis has emerged as a mild and potent tool for the single electron reduction of unactivated alkyl chlorides,opening up new possibilities in this field.Considering the rapid advancements in this area,a comprehensive review that provides a conceptual understanding of this emerging field,with a specific focus on reaction design and catalytic mechanisms,would be timely and highly valuable.Hence,we present an overview of various synthetic techniques for photoinduced single electron reduction of unactivated alkyl chlorides.Furthermore,we also discuss the limitations of the present methods and future directions that lie ahead in this field.

关键词： photocatalysis unactivated alkyl chlorides single electron transfer radical reactions

Understanding the involvement of supports in the catalysis of atomically dispersed metal catalysts

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Science Bulletin 2018年第11期63卷 669-671页

作者： Lei Dai Hua Zhang Center for Programmable Materials School of Materials Science and Engineering Nanyang Technological University

Supported metal nanoparticles are widely used as heterogeneous catalysts in chemical,food,energy and environmental industry.Due to the high surface energy of metal nanoparticles,the supports are highly important to stabilize the metal nanoparticles and protect them from sintering during catalytic reactions.In many cases,the interfaces formed between the metal components and supports also determine the

关键词：金属催化剂催化作用原子化学药品催化反应金属部件精力表面

Estimation of IIR Systems with Binary-Valued Observations

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Chinese Annals of Mathematics,Series B 2023年第5期44卷 687-702页

作者： Ruifen dai lei GUO Data Science Institute Shandong UniversityJinan 250100China Key Laboratory of Systems and Control Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

Estimation and control problems with binary-valued observations exist widely in practical systems.However,most of the related works are devoted to finite impulse response(FIR for short)systems,and the theoretical problem of infinite impulse response(IIR for short)systems has been less explored.To study the estimation problems of IIR systems with binary-valued observations,the authors introduce a projected recursive estimation algorithm and analyse its global convergence properties,by using the stochastic Lyapunov function methods and the limit theory on double array martingales.It is shown that the estimation algorithm has similar convergence results as those for FIR systems under a weakest possible non-persistent excitation condition.Moreover,the upper bound for the accumulated regret of adaptive prediction is also established without resorting to any excitation condition.

关键词： Binary-valued observations Infinite impulse response Adaptive estimation Double array martingales Adaptive prediction

Modeling the dynamic performance of transportation infrastructure using panel data model in state-space specifications

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第3期10卷 441-453页

作者： Bingye Han Zengming Du Lei Dai Jianming Ling Fulu Wei School of Civil and Transportation Engineering Beijing University of Civil Engineering and ArchitectureBeijing 100044China Jiangsu Technology Industrialization and Research Center of Ecological Road Engineering Suzhou 215011China Key Laboratory of Infrastructure Durability and Operation Safety in Airfield of CAAC Shanghai 201804China Foshan Construction&Development Group Co. Ltd.Foshan 528000China Key Laboratory of Road and Traffic Engineering of Ministry of Education Tongji UniversityShanghai 200092China China Construction Eighth Engineering Division Co. Ltd.Shanghai 200082China Lyles School of Civil Engineering Purdue UniversityWest LafayetteIN 47907USA

In this study,different modeling approaches used in panel data for performance forecast of transportation infrastructure are firstly reviewed,and the panel data models(PDMs)are highlighted for longitudinal data sets.The state-space specification of PDMs are proposed as a framework to formulate dynamic performance models for transportation facilities and panel data sets are used for estimation.The models could simultaneously capture the heterogeneity and update forecast through inspections.PDMs are applied to tackle the cross-section heterogeneity of longitudinal data,and PDMs in state-space forms are used to achieve the goal of updating performance forecast with new coming data.To illustrate the methodology,three classes of dynamic PDMs are presented in four examples to compare with two classes of static PDMs for a group of composite pavement sections in an airport in east China.Estimation results obtained by ordinary least square(OLS)estimator and system generalized method of moments(SGMM)are compared for two dynamic instances.The results show that the average root mean square errors of dynamic specifications are all significantly lower than those of static counterparts as prediction continues over time.There is no significant difference of prediction accuracy between state-space model and curve shifting model over a short time.In addition,SGMM does not obtain higher prediction accuracy than OLS in this case.Finally,it is recommended to specify the inspection intervals as several constants with integer multiples.

关键词： Infrastructure performance modeling Dynamic models State-space models Pavement condition index Ordinary least square Generalized method of moments

Light-induced phosphine-catalyzed asymmetric functionalization of benzylic C–H bonds

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Science China Chemistry 2023年第1期66卷 127-132页

作者： Jiami Guo Zi-An Shen Xueting Zhou Lei Dai Yixin Lu Joint School of National University of Singapore and Tianjin University International Campus of Tianjin University Binhai New CityFuzhou 350207China Department of Chemistry National University of SingaporeSingapore 117543Singapore

Despite rapid development in the past two decades,there are still some unsolved synthetic challenges in the field of phosphine catalysis.In this report,through photo-induced activation of ortho-alkyl aromatic ketones,we achieved highly enantioselective functionalization of substrates bearing a benzylic C–H bond.In the presence of amino acid-derived bifunctional phosphine catalysts,a range of benzylic allylation products were obtained in good yields and with excellent enantioselectivities.The strategy disclosed herein offers new insight into the activation and functionalization of pronucleophiles containing less acidic C–H bonds in the domain of phosphine catalysis and beyond.

关键词： phosphine catalysis nucleophilc catalysis enantioselective benzylic C-H bonds

Ultrathin and flexible MXene-contained electromagnetic interference shielding composite paper designed with a protective hydrogel film

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Journal of Materials Science & Technology 2024年第2期169卷 199-208页

作者： Jiasheng Wei Lei Dai Ping He Meng Zhu Feng Jiang Zhaoxiang Zhou Guiqiang Fei Tingzhou lei College of Bioresources Chemical and Materials Engineering Shaanxi University of Science and TechnologyXi’an 710021China Key Laboratory of Eco-Textiles Ministry of EducationJiangnan UniversityWuxi 214122China Zhejiang Shunpu New Material Technology Co. LtdLongyou 324404China College of Chemistry and Chemical Engineering Shaanxi University of Science and TechnologyXi’an 710021China National-Local Joint Engineering Research Center of Biomass Refining and High-Quality Utilization Institute of Urban and Rural MiningChangzhou UniversityChangzhou 213164China

MXene-contained paper is a good choice to design ultrathin and flexible electromagnetic interference(EMI)shielding materials.However,the deficiencies in strength and stability of MXene-contained paper impede its practical applications.Herein,a composite paper was proposed to address the problems,in which a filter paper was modified with a three-layer structured surface via a facile layer-by-layer coating procedure.Specifically,the TEMPO-oxidized cellulose nanofibers(TOCN)/cationic starch(CS)/MXene gel layer and TOCN/MXene nacre structure layer ensured the good EMI shielding and mechanical performances of the composite paper,while the uppermost TOCN/CS hydrogel film layer mainly protected MXene.The composite paper achieved an EMI SE of 40.3 dB at a thickness of merely 0.1894 mm(SE/t value of ca.212.8 dB mm^(−1),SSE/t values of ca.13216 dB cm 2 g^(−1))and the total MXene dosage was 20 g m^(−2).Its tensile strength could be up to 11.7 MPa while the original filter paper was 6.4 MPa.Four pieces of this composite papers could be easily packed together to attain an EMI SE of nearly 70 dB.Importantly,the hydrogel film layer efficiently protected the MXene and maintained the EMI shielding performance of the composite paper when immersed in different liquids including water,HCl(1 M)and ethanol,due to the dense and compact structure of hydrogel film layer.This work provides a practical way to develop ultrathin,flexible and durable EMI shielding materials.

关键词： MXene Electromagnetic interference shielding Nanocellulose Hydrogel

Property(ω)and the Single-valued Extension Property

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Acta Mathematica Sinica,English Series 2021年第8期37卷 1254-1266页

作者： Lei Dai Xiao Hong CAO Qi GUO School of Mathematics and Statistics Weinan Normal UniversityWeinan 714099P.R.China School of Computer Science Shaanxi Normal UniversityXi’an 710119P.R.China School of Mathematics and Information Science Shaanxi Normal UniversityXi’an 710119P.R.China

By the new spectrum originated from the single-valued extension property,we give the necessary and sufficient conditions for a bounded linear operator defined on a Banach space for which property(ω)holds.Meanwhile,th... 详细信息

关键词： Property(ω) the single-valued extension property hypercyclic property supercyclic property

The effects of different electrode materials on seed germination of Solanum nigrum L.and its Cd accumulation in soil

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Journal of Environmental Sciences 2022年第3期34卷 291-299页

作者： lei Xu Huiping dai Lidia Skuza Shuhe Wei Key Laboratory of Pollution Ecology and Environment Engineering Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China College of Biological Science&Engineering Shaanxi Province Key Laboratory of Bio-resourcesShaanxi University of TechnologyHanzhong 723001China Institute of Biology Centre for Molecular Biology and BiotechnologyUniversity of SzczecinSzczecin 71-415Poland University of Chinese Academy of Sciences Beijing 100039China

The effects of different electrode on Solanum nigrum L.seed germination were determined.The result showed that germination percentage(GP)of seeds in treatment T2(titanium elec-trode)was 26.6%higher than in control(CK,without electric field).High potassium and calcium concentrations were beneficial for seed enzymatic activity in treatment T2,which could partly explain the increase in GP.Cd accumulation(μg/pot)in S.nigrum treated with any electric field was significantly higher(p<0.05)than in CK without electric field.Specif-ically,Cd accumulation under the treatment T3(stainless steel electrode)was the highest both in roots and shoots;this accumulation in shoots and roots were 74.7%and 67.4%higher for stainless steel than in CK.This increase must have been associated with a higher Cd concentration in plants and did not exert a significant effect on the biomass.In par-ticular,Cd concentrations in roots and shoots under stainless steel treatment were both significantly higher than in CK(p<0.05),which had to be related to the higher available Cd concentration in the soil in the middle region.Furthermore,it could be attributed to al-tered soil pH and other soil properties.Moreover,none of the biomasses were significantly affected(p<0.05)by different electrode materials compared to CK.

关键词： Cd contaminated soil Solanum nigrum L. DC electric field Electrode materials Seed germination