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Recent Advances in Radical-Mediated C-C Bond Fragmentation of Non-Strained Molecules

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Chinese Journal of Chemistry 2019年第2期37卷 171-182页

作者： xinxin wu Chen Zhu Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials ScienceSoochow University199 Ren-Ai RoadSuzhouJiangsu 215123China Key Laboratory of Synthetic Chemistry of Natural Substances Shanghai Institute of Organic ChemistryChinese Academy of Sciences345 Lingling RoadShanghai 200032China

The carb on-carbon (C-C) σ-bonds construct the fundame ntal frameworks of organic molecules. The direct fun ctionalization of C-C bonds represe nts one of the most efficient and step-economical transformations in synthetic chemistry. The past few decades have witnessed the fast development of transition-metal mediated C-C bond activation.

关键词： Recent Advances Radical-Mediated C-C Bond Fragmentation Non-Strained Molecules

Effects of Surface Oxidation Treatment of Carbon Fibers on Biotribological Properties of CF/PEEK Materials

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Journal of Bionic Engineering 2017年第4期14卷 640-647页

作者： Xiaoduo Zhao Dangsheng Xiong xinxin wu School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China

Carbon Fiber （CF） reinforced polyetheretherketone （PEEK） composite is one of the most promising implant biomaterials used in orthopedics. In this article, unfilled PEEK and CF/PEEK specimens were prepared by vacuum hot pressing method, and their tribological properties were evaluated by sliding against a cobalt-chromium-molybdenum （Co-Cr-Mo） alloy block. The influences of mass fraction of carbon fibers in CF/PEEK and the surface oxidation treatment of carbon fibers were explored. The results showed that the water contact angles on the surfaces of CF/PEEK specimens decreased, indicating that their surface wettability was improved. The hardness value of CF/PEEK was significantly improved, the friction coefficients of CF/PEEK were effectively reduced and its wear resistance was enhanced compared with unfilled PEEK. The leading effect on CF/PEEK tribological properties was the mass fraction of CF, followed by surface oxidation of CF, and the calf serum solution had better lubricity than that of saline and deionized water.

关键词： CF/PEEK biocomposites surface oxidation treatment lubrication wear mechanism

New friction factor and Nusselt number equations for laminar forced convection of liquid with variable properties

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Science China(Technological Sciences) 2018年第1期61卷 98-109页

作者： ZHAO HouJian LI XiaoWei wu xinxin Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Collaborative Innovation Center of Advanced Nuclear Energy Technology Institute of Nuclear and New Energy Technology Tsinghua University

Friction factor and heat transfer coefficient of liquid flow with variable properties can significantly differ from that with constant properties. Existing equations obtained by regression analysis of experimental data use correction factors to account for variable property effect. They are limited to specific kind of fluid and low or medium temperature differences. The correction factors of the equations for heating and cooling conditions are different. New explicit friction factor and Nusselt number equations for laminar forced convection of liquid with variable properties are derived with a first order approximation of dynamic viscosity-temperature variation. The new equations are applicable to all kinds of liquids and can be used for large temperature differences. Governing equations of laminar forced convection of water and ethanol are numerically solved using computational fluid dynamics(CFD)method and the results are used to verify the derived equations. The derived equations show good predictions of friction factors and Nusselt numbers for both heating and cooling conditions and show more accurate predictions than the existing equations. A dimensionless number is also introduced based on theoretical analysis to evaluate property variation effects on friction factors and heat transfer coefficients.

关键词： laminar convection friction factor heat transfer coefficient variable property

Regioselective introduction of vinyl trifluoromethylthioether to remote unactivated C(sp^3)–H bonds via radical translocation cascade

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Science China Chemistry 2019年第11期62卷 1507-1511页

作者： Shuo wu xinxin wu Zhen wu Chen Zhu Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials ScienceSoochow UniversityJiangsu 215123China Key Laboratory of Synthetic Chemistry of Natural Substances Shanghai Institute of Organic ChemistryShanghai 200032China

Described herein is an efficient protocol for the regioselective introduction of a vinyl trifluoromethylthioether to remote unactivated C(sp3)–H *** cascade process involves the vinyl radical-mediated 1,5-hydrogen atom transfer(HAT)and remote vinyl *** the transformation,inert C–H and C–C bonds are consecutively cleaved under mild *** reaction features good functional group tolerance,broad substrate scope,and high regio-/stereo-selectivity.

关键词： C–H functionalization hydrogen atom transfer vinyl migration vinyl radical trifluoromethylthio radical

Multipurpose sulfoximine-mediated radicalγ-heteroarylation of unactivated C(sp^(3))–H bonds

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Science China Chemistry 2023年第5期66卷 1435-1442页

作者： Yuqian Sun xinxin wu Zhu Cao Chen Zhu Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials ScienceSoochow UniversitySuzhou 215123China Frontiers Science Center for Transformative Molecules and Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs Shanghai Jiao Tong UniversityShanghai 200240China

A conceptually novel,trifunctional sulfoximine-mediatedγ-functionalization of unactivated C(sp^(3))–H bonds has been *** reaction is initiated by the photo-induced homolytic cleavage of an N–S bond in the absence of photosensitizer,and proceeds sequentially through a cascade of 1,5-hydrogen atom transfer,1,4-functional group migration,desulfoximination and a Minisci reaction.A major feature of this approach is the use of sulfoximine as a traceless directing *** positive properties include mild conditions,simple operation,exclusive site-selectivity,high product diversity and the avoidance of additional *** protocol provides a new reaction mode for HAT-induced C(sp^(3))–H functionalization,and allows a much broader chemical space for sulfoximine studies.

关键词： sulfoximine hydrogen atom transfer functional group migration C(sp^(3))–H functionalization heteroarylation photochemistry

A practical access to fluoroalkylthio(seleno)-functionalized bicyclo[1.1.1]pentanes

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Science China Chemistry 2020年第8期63卷 1025-1029页

作者： Zhen wu Yaohui Xu Jige Liu xinxin wu Chen Zhu Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials ScienceSoochow UniversitySuzhou 215125China

Rational design of new bioisosteres through introduction of high-value functional groups to bicyclo[1.1.1]pentane(BCP)is of particular use for drug *** herein is the first access to valuable fluoroalkylthio(seleno)-functionalized BCPs.A range of SCF3,SCF2H,SCFH2,SeCF3,SeC4F9,and SeC8F17 groups are readily incorporated to BCPs under mild *** installation of a sulfone provides a platform for incorporation of the BCP motif to bioactive *** practical protocol features novel BCP scaffolds,broad substrate scope,excellent atom-economy,simple operation,and gramscale preparation.

关键词： bicyclo[1.1.1]pentane propellane bioisostere trifluoromethylthio trifluoromethylseleno

Simulating multiple urban land use changes by integrating transportation accessibility and a vector-based cellular automata:a case study on city of Toronto

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Geo-Spatial Information Science 2022年第3期25卷 439-456页

作者： Xiaocong Xu Dachuan Zhang Xiaoping Liu Jinpei Ou xinxin wu School of Geography and Planning Guangdong Key Laboratory for Urbanization and Geo-simulationSun Yat-Sen UniversityGuangzhouChina Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) ZhuhaiChina

The accessibility provided by the transportation system plays an essential role in driving urban growth and urban functional land use *** studies on land use simulation usually simplified the accessibility as proximities and adopted the grid-based simulation strategy,leading to the insufficiencies of characterizing spatial geometry of land parcels and simulating subtle land use changes among urban functional *** overcome these limita-tions,an Accessibility-interacted Vector-based Cellular Automata(A-VCA)model was proposed for the better simulation of realistic land use change among different urban functional *** accessibility at both local and zonal scales derived from actual travel time data was considered as a key driver of fine-scale urban land use changes and was integrated into the vector-based CA simulation *** proposed A-VCA model was tested through the simulation of urban land use changes in the City of Toronto,Canada,during 2012-2016.A vector-based CA without considering the driving factor of accessibility(VCA)and a popular grid-based CA model(Future Land Use Simulation,FLUS)were also implemented for *** simulation results reveal that the proposed A-VCA model is capable of simulating fine-scale urban land use changes with satisfactory accuracy and good morphological feature(kappa=0.907,figure of merit=0.283,and cumulative producer’s accuracy=72.83%±1.535%).The comparison also shows significant outperformance of the A-VCA model against the VCA and FLUS models,suggesting the effectiveness of the accessibility-interactive mechanism and vector-based simulation *** proposed model provides new tools for a better simula-tion of fine-scale land use changes and can be used in assisting the formulation of urban and transportation planning.

关键词： Urban land use change simulation transportation accessibility Vector-based cellular automata(VCA)

Radical Heteroarylalkylation of Alkenes via Three-Component Docking-Migration Thioetherification Cascade

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Chinese Journal of Chemistry 2020年第8期38卷 803-806页

作者： Tao Niu Jige Liu xinxin wu Chen Zhu Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials ScienceSoochow University199 Ren-Ai RoadSuzhouJiangsu 215123China Key Laboratory of Synthetic Chemistry of Natural Substances Shanghai Institute of Organic ChemistryChinese Academy of Sciences345 Lingling RoadShanghai 200032China

A novel,rational-designed approach to access various heteroaryl-substituted alkyl thioethers was developed via docking-migration cascade *** utilizing three components involving alkene,dual-function reagent,and thioetherificating reagent,radical heteroarylalkylation of alkenes followed by thiolation of the alkyl radical intermediates proceeded smoothly,manifesting well compatibility of substrates and cascade ***,this protocol also features mild conditions,broad substrate scope,and wide product diversity.

关键词： process reagent alkylation

Radical Functionalization of Remote C(sp^(3))-H Bonds Mediated by Unprotected Alcohols and Amides

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CCS Chemistry 2020年第5期2卷 813-828页

作者： xinxin wu Chen Zhu Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials ScienceSoochow UniversitySuzhouJiangsu 215123

Aliphatic alcohols and amides are highly valued,ubiquitous chemicals in synthetic ***-promoted regioselective functionalization of unactivated C(sp^(3))–H bonds offers an atom and step economic manner for direct transformation of aliphatic alcohols and amides,especially structural elaboration of complex natural products and bioactive molecules without de novo *** the rapid growth of hydrogen atom transfer(HAT)processes mediated by O-or N-centered radicals generated from prefunctionalized precursors of alcohols and amides in the past few years,exploration of remote C(sp^(3))–H functionalization via HAT mediated by unprotected alcohols or amides lags behind,due to the difficult homolysis of O–H and N–H bonds with high bond-dissociation energies(BDEs).In this minireview,the recent advances in regioselective C(sp^(3))–H functionalization mediated by unprotected alcohols and amides are summarized.

关键词： C(sp^(3))–H functionalization hydrogen atom transfer alcohols amides regioselectivity radical reactions