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Polyolefin vitrimers bearing acetoacetate functionality

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Science China Chemistry 2024年

作者： Zihao Wang Yue Liu wenmin pang Ao Chen Min Chen Chinese Academy of Sciences (CAS) Key Laboratory of Soft Matter Chemistry Department of Polymer Science and Engineering University of Science and Technology of China Institutes of Physical Science and Information Technology Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education Anhui University

Polyolefin vitrimers are polymer networks bearing reversible covalent crosslinking points, enabling them to be reprocessed and recycled. In this contribution, a series of polyolefin vitrimers were designed based on the acetoacetate-functionalized polyolefin copolymers, which were produced through the direct copolymerization of ethylene with polar comonomers using a phosphinesulfonate palladium catalyst. The pendant acetoacetate group could mediate several characteristic reactions, such as the Michael addition reaction, ketone-amine condensation and metal coordination reaction. As such, structurally adjustable polyolefin vitrimers can be accessed by introducing various dynamic crosslinking bonds, including disulfide exchange, transamination of vinylogous urethane and labile metal coordination bond. The utilization of different crosslinking reactions and the mole ratio of crosslinkers significantly impact the material properties of the resultant polymers. Specifically, the generated polyolefin vitrimers demonstrated excellent reprocessability and closed-loop recycling properties. The study in this work provides an efficient strategy to access various polyolefin vitrimers.

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Influence of chelate ring size on the properties of phosphine-sulfonate palladium catalysts

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Science China Chemistry 2018年第9期61卷 1175-1178页

作者： Chen Zou wenmin pang Changle Chen CAS Key Laboratory of Soft Matter Chemistry i Ch EM (Collaborative Innovation Center of Chemistry for Energy Materials) Department of Polymer Science and Engineering University of Science and Technology of China

Phosphine-sulfonate based palladium is one of the most extensively studied catalyst systems in olefin *** type of catalyst features six-membered chelate ring size,and can enable the copolymerizations of ethylene with a wide variety of polar *** this contribution,we decide to investigate the influence of chelate ring size on the properties of phosphinesulfonate palladium *** such,a series of phosphine-sulfonate ligands and the corresponding seven-membered ring Pd(II)complexes[κ~2-(P,O)-2-(CH_2-PR_1R_2)-4-methylphenyl-sulfonato]Pd(Me)(DMSO)(Pd1,R_1=R_2=Cy,Pd2,R_1=R_2=o-Me O-C_6H_4;Pd3,R_1=Ph,R_2=2-[2,6-(Me O)_2C_6H_3]C_6H_4;DMSO=dimethyl sulfoxide)were designed,prepared and *** palladium complexes are moderately active when they were applied in ethylene polymerization and copolymerizations with methyl acrylate and butyl vinyl ***,their properties are greatly reduced from those of the classic six-membered ring phosphine-sulfonate palladium complex Pd2′.The experimental results indicate that the bigger chelate ring size can increase the ligand flexibility and damage the catalytic properties for the phosphine-sulfonate type palladium catalysts.

关键词： ethylene polymerization polar monomer chelate ring size phosphine-sulfonate palladium catalysts

Lewis acid/base modulation in β-diiminate zinc-catalyzed switchable ring-opening polymerization of rac-lactide

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Science China Chemistry 2019年第4期62卷 475-478页

作者： Pan Zhang Minhui Zhao wenmin pang Changle Chen Hefei National Laboratory for Physical Sciences at the Microscale Chinese Academy of Sciences Key Laboratory of Soft Matter ChemistryDepartment of Polymer Science and Engineering University of Science and Technology of China

Two β-diiminate zinc complexes were prepared and found to show high activity and well-controlled catalytic behavior in the ring-opening polymerization of rac-lactide. Coordination of the Lewis acid to the zinc complexes completely terminated the polymerization. The coordinated Lewis acid was easily cleaved by using a Lewis base, so that the polymerization could ***, switchable polymerization could be realized by the subsequent addition of a Lewis acid and a Lewis base. This work provides a new strategy to control the ring-opening polymerization of rac-lactide.

关键词： ring-opening polymerization β-diimine zinc catalysts modulation

Positional Electronic Effects in Iminopyridine-N-oxide Nickel Catalyzed Ethylene Polymerization

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Chinese Journal of Chemistry 2021年第6期39卷 1683-1689页

作者： Mingjun Chi Ao Chen wenmin pang Chen Tan Changle Chen CAS Key Laboratory of Soft Matter Chemistry Hefei National Laboratory for Physical Sciences at the MicroscaleDepartment of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefeiAnhui 230026China Institutes of Physical Science and Information Technology Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of EducationAnhui UniversityHefeiAnhui 230026China

A series of dibenzhydryl-based iminopyridine-N-oxide ligands bearing a range of electron-donating or-withdrawing substituents(OMe,H;and NO_(2))and corresponding nickel pre-catalysts are prepared and *** substituents are installed at different positions on the ligand structure,including 4-position of the pyridine-N-oxide moiety(position X)and 4-position of the aniline moiety(position Y).These nickel pre-catalysts are highly active in ethylene polymerization with the addition of very little amount of aluminum cocatalysts,leading to the formation of polyethylenes with molecular weights of well above one ***-donating substituents make the catalysts sensitive to polymerization *** contrast,the catalysts bearing electron-withdrawing NO_(2) substituents show relatively steady performances at different *** importantly,we demonstrate that different substituents and different positions both play important roles in determining the properties of nickel *** provides an alternative strategy for the future design of high-performance polymerization catalyst.

关键词： Ethylene Polymerization Nickel lminopyridine-N-oxide Substituent effects

SiO_(2)-Supported Ni(II)and Fe(II)Catalysts Bearing Sodium-Sulfonate Group for Olefin Polymerization

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Chinese Journal of Chemistry 2022年第23期40卷 2773-2779页

作者： Yao Sun Quan Wang Yao Pan wenmin pang Chen Zou Min Chen CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefeiAnhui 230026China Institutes of Physical Science and Information Technology Anhui UniversityHefeiAnhui 230601China

Heterogeneous catalysts have been dominant for industrial polyolefin production,offering many distinct advantages,such as controlling the morphology of the polymer and preventing reactor *** this contribution,we designed several types of imine ligands bearing sodium-sulfonate ionic groups and the corresponding nickel/iron *** catalysts could be immobilized on SiO_(2)with strong affinity and high catalyst *** SiO_(2)-supported catalysts behaved better than their homogeneous counterparts during ethylene polymerization with extremely high activity(2.6×10^(4)kg·mol^(−1)·h^(−1))and high thermal *** addition,the supported nickel catalysts generated free-flowing polyethylene with high molecular weight(Mn up to 2.65×10^(3)kg·mol^(–1))and excellent morphology control,indicating no reactor fouling due to the leaching of ***,for copolymerization,immobilized nickel catalysts showed a higher tolerance of polar monomers,and the efficient copolymerization of ethylene with undecylenic acid was achieved with high activity(450 kg·mol^(−1)·h^(−1))and a high incorporation ratio(up to 12.3%).

关键词： Heterogeneous catalysis Nickel iron catalysts Sodium-sulfonate group Polymerization Copolymerization

Early Triassic Silicic Volcanics of South China:Petrogenesis and Constraints on the Geodynamic Evolution of the Paleo-Tethys Ocean Region

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Acta Geologica Sinica(English Edition) 2024年第3期98卷 617-629页

作者： WANG Yabo LIU Lei ZHAO Zengxia LIU Xijun HUANG wenmin Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration College of Earth SciencesGuilin University of TechnologyGuilinGuangxi 541004China Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources Guilin University of TechnologyGuilinGuangxi 541004China

The only occurrence of Lower Triassic silicic volcanic rocks within the South China Block is in the Qinzhou Bay area of Guangxi ***-ICP-MS zircon U-Pb dating reveals that volcanic rocks of the Beisi and Banba formations formed between 248.8±1.6 and 246.5±1.3 Ma,coeval with peraluminous granites of the Qinzhou Bay Granitic *** studied rhyolites and dacites are characterized by high SiO_(2),K_(2)O,and Al_(2)O_(3),and low MgO,CaO,and P_(2)O_(5) contents and are classified as high-K calc-alkaline S-type rocks,with A/CNK=*** volcanic rocks are depleted in high field strength elements,e.g.,Nb,Ta,Ti,and P,and enriched in large ion lithophile elements,e.g.,Rb,K,Sr,and *** the analyzed volcanic rocks have extremely enriched zircon Hf isotopic compositions(ε_(Hf)(t)=-29.1 to-6.9),source discrimination indicators and high calculated Ti-in-zircon temperatures(798-835℃)reveal that magma derived from enriched lithospheric mantle not only provided a heat source for anatectic melting of the metasedimentary protoliths but was also an endmember component of the S-type silicic *** studied early Triassic volcanics are inferred to have formed immediately before closure of the Paleo-Tethys Ocean in this region,as the associated subduction would have generated an extensional setting in which the mantle-derived upwelling and volcanic activity occurred.

关键词： geochemistry silicic volcanic rocks mantle contribution Olenekian-Anisian Paleo-Tethys oceanic plate subduction

NORMALIZED SOLUTIONS FOR THE GENERAL KIRCHHOFF TYPE EQUATIONS

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Acta Mathematica Scientia 2024年第5期44卷 1886-1902页

作者： wenmin LIU Xuexiu ZHONG Jinfang ZHOU School of Mathematical Sciences South China Normal UniversityGuangzhou510631China South China Research Center for Applied Mathematics and Interdisciplinary Studies&School of Mathematical Sciences South China Normal UniversityGuangzhou510631China

In the present paper,we prove the existence,non-existence and multiplicity of positive normalized solutions(λ_(c),u_(c))∈ℝ×H^(1)(ℝ^(N))to the general Kirchhoff problem-M\left(\int_{\mathbb{R}^N}\vert\nabla u\vert^2{\rm d}x\right)\Delta u+\lambda u=g(u)~\hbox{in}~\mathbb{R}^N,u\in H^1(\mathbb{R}^N),N\geq 1,satisfying the normalization constraint\int_{\mathbb{R}^N}u^2{\rm d}x=c,where M∈C([0,∞))is a given function satisfying some suitable *** argument is not by the classical variational method,but by a global branch approach developed by Jeanjean et al.[J Math Pures Appl,2024,183:44–75]and a direct correspondence,so we can handle in a unified way the nonlinearities g(s),which are either mass subcritical,mass critical or mass supercritical.

关键词： normalized solution Kirchhoff type equations general nonlinearities asymptotic behavior

Porous nanofibrous dressing enables mesenchymal stem cell spheroid formation and delivery to promote diabetic wound healing

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Chinese Journal of Chemical Engineering 2024年第4期68卷 156-164页

作者： Kexin Zhang wenmin Zhang Heng An Zhe Huang Yanzhen Wen Xiangyu Jiao Yongqiang Wen College of Chemical Engineering and Technology Taiyuan University of Science and TechnologyTaiyuan 030024China Beijing Key Laboratory for Bioengineering and Sensing Technology Daxing Research InstituteSchool of Chemistry&Biological EngineeringUniversity of Science&Technology BeijingBeijing 100083China

Delayed and nonhealing of diabetic wounds imposes substantial economic burdens and physical pain on *** stem cells(MSCs)promote diabetic wound *** when MSCs aggregate into multicellular spheroids,their therapeutic effect is ***,traditional culture platforms are inadequate for the efficient preparation and delivery of MSC spheroids,resulting in inefficiencies and inconveniences in MSC spheroid *** this study,a three-dimensional porous nanofibrous dressing(NFD)is prepared using a combination of electrospinning and homogeneous *** thermal crosslinking,the NFD not only achieves satisfactory elasticity but also maintains notable *** the design of its structure and chemical composition,the NFD allows MSCs to spontaneously form MSC spheroids with controllable sizes,serving as MSC spheroid delivery systems for diabetic wound *** importantly,MSC spheroids cultured on the NFD exhibit improved secretion of vascular endothelial growth factor,basic fibroblast growth factor,and hepatocyte growth factor,thereby accelerating diabetic wound *** NFD provides a competitive strategy for MSC spheroid formation and delivery to promote diabetic wound healing.

关键词： Electrospinning Homogenization Biomedical engineering Nanomaterials Stem cell spheroids Diabetic wound healing

A Deep Neural Collaborative Filtering Based Service Recommendation Method with Multi-Source Data for Smart Cloud-Edge Collaboration Applications

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Tsinghua Science and Technology 2024年第3期29卷 897-910页

作者： wenmin Lin Min Zhu Xinyi Zhou Ruowei Zhang Xiaoran Zhao Shigen Shen Lu Sun Alibaba Business School Hangzhou Normal UniversityHangzhou 311121China Blockchain Laboratory of Agricultural Vegetables Weifang University of Science and TechnologyShouguang 262700China School of Computer Science Qufu Normal UniversityRizhao 276827China School of Information Engineering Huzhou UniversityHuzhou 313000China

Service recommendation provides an effective solution to extract valuable information from the huge and ever-increasing volume of big data generated by the large cardinality of user ***,the distributed and rich multi-source big data resources raise challenges to the centralized cloud-based data storage and value mining approaches in terms of economic cost and effective service recommendation *** view of these challenges,we propose a deep neural collaborative filtering based service recommendation method with multi-source data(i.e.,NCF-MS)in this paper,which adopts the cloud-edge collaboration computing paradigm to build recommendation *** specifically,the Stacked Denoising Auto Encoder(SDAE)module is adopted to extract user/service features from auxiliary user profiles and service *** Multiple Layer Perceptron(MLP)module is adopted to integrate the auxiliary user/service features to train the recommendation ***,we evaluate the effectiveness of the NCF-MS method on three public *** experimental results show that our proposed method achieves better performance than existing methods.

关键词： deep neural collaborative filtering multi-source data cloud-edge collaboration application stackeddenoising auto encoder multiple layer perceptron