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Double stimulus-responsive palladium catalysts for ethylene polymerization and copolymerization

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Chinese Chemical Letters 2024年第7期35卷 407-411页

作者： Hailong He Wenbing Wang Wenmin Pang Chen zou Dan Peng CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei National Laboratory for Physical Sciences at the MicroscaleHefei 230026China

The external stimulus response strategy has been evolved rapidly in the field of olefin *** this work,we modularly synthesized three types of double stimulus responsiveα-diimine palladium catalysts,combining redox regulation and other regulation together,such as light,Lewis acid and alkali *** catalytic activities and the molecular weight of polyethylene products can be regulated for 4 times in ethylene *** palladium complexes were also used for the copolymerization reaction of ethylene and polar monomers,such as methyl 10-undecylenate and methyl acrylate,effectively regulating the catalytic activities,the molecular weight and polar monomer incorporation of the prepared *** research on these dual-regulated palladium complexes makes full use of prepared catalysts and provides new inspirations for regulating olefin polymerization.

关键词： Dual-regulated Stimulus-responsive Palladium Ethylene polymerization Polar monomer

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Synthesis of Ultra-High-Molecular-Weight Polyethylene by Transition-Metal-Catalyzed Precipitation Polymerization

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Precision Chemistry 2024年第2期2卷 63-69页

作者： Wenbing Wang Quan Wang Chen zou Changle Chen Key Laboratory of Precision and Intelligent Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China

Ultra-high-molecular-weight polyethylene(UHMWPE)plays an important role in many important fields as engineering *** this contribution,a precipitation polymerization strategy is developed by combination of highly active phosphino-phenolate nickel catalysts with polymer-insoluble solvent(heptane)to access UHMWPE(Mn up to 8.3×10^(6)g mol^(-1))with good product morphology,free-flowing characteristics,and great mechanical *** with the academically commonly used aromatic solvent(toluene),the utilization of heptane offers simultaneous enhancement in important parameters including activity,polymer molecular weight,and catalyst thermal *** system can also generate polar functionalized UHMWPE with molecular weight of up to 1.6×10^(6)g mol^(-1)in the copolymerization of ethylene with polar *** importantly,this precipitation polymerization strategy is generally applicable to several representative transition metal catalyst systems,leading to UHMWPE synthesis with good product morphology control.

关键词： transition metal catalysts polyolefin UHMWPE precipitation polymerization polar monomer

Nickel catalysts with asymmetric steric hindrance for ethylene polymerization

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中国科学技术大学学报 2024年第6期54卷 48-52,59,I0010,I0011页

作者： Wanlu Tian Fuzhou Wang Chen zou Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China

α-Diimide catalysts have attracted widespread attention due to their unique chain walking characteristics.A series ofα-diimide nickel/palladium catalysts with different electronic effects and steric hindrances were designed and synthesized for olefin *** this work,we synthesized a series of asymmetricα-diimide nickel complexes with different steric hindrances and used them for ethylene *** nickel catalysts have high ethylene polymerization activity,up to 6.51×10^(6)g·mol^(−1)·h^(−1),and the prepared polyethylene has a moderate melting point and high molecular weight(up to 38.2×10^(4)g·mol^(−1)),with a branching density distribution between 7 and 94 branches per 1000 *** importantly,the polyethylene prepared by these catalysts exhibits excellent tensile properties,with strain and stress reaching 800%and 30 MPa,respectively.

关键词： α-diimine nickel complex polyethylene polymerization asymmetric steric hindrance

Bioinspired polysaccharide-based nanocomposite membranes with robust wet mechanical properties for guided bone regeneration

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National Science Review 2024年第3期11卷 215-226页

作者： Jian-Hong Xiao Zhen-Bang Zhang JiaHao Li Si-Ming Chen Huai-Ling Gao YinXiu Liao Lu Chen ZiShuo Wang YiFan Lu YuanZhen Hou HengAn Wu DuoHong zou Shu-Hong Yu Department of Chemistry New Cornerstone Science Laboratory Institute of Biomimetic Materials&Chemistry Anhui Engineering Laboratory of Biomimetic MaterialsDivision of Nanomaterials&Chemistry Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of China Department of Dental Implant Center Stomatologic Hospital and College Key Laboratory of Oral Diseases Research of Anhui Province Anhui Medical University CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Department of Oral Surgery College of Stomatology National Clinical Research Center for Oral DiseasesShanghai Key Laboratory of Stomatology Shanghai Research Institute of Stomatology Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine Institute of Innovative Materials(I2M) Department of Chemistry Department of Materials Science and Engineering Southern University of Science and Technology

Polysaccharide-based membranes with excellent mechanical properties are highly desired. However, severe mechanical deterioration under wet conditions limits their biomedical applications. Here, inspired by the structural heterogeneity of strong yet hydrated biological materials, we propose a strategy based on heterogeneous crosslink-and-hydration（HCH） of a molecule/nano dual-scale network to fabricate polysaccharide-based nanocomposites with robust wet mechanical properties. The heterogeneity lies in that the crosslink-and-hydration occurs in the molecule-network while the stress-bearing nanofiber-network remains unaffected. As one demonstration, a membrane assembled by bacterial cellulose nanofiber-network and Ca2+-crosslinked and hydrated sodium alginate molecule-network is designed. Studies show that the crosslinked-and-hydrated molecule-network restricts water invasion and boosts stress transfer of the nanofiber-network by serving as interfibrous bridge. Overall, the molecule-network makes the membrane hydrated and flexible; the nanofiber-network as stress-bearing component provides strength and *** HCH dual-scale network featuring a cooperative effect stimulates the design of advanced biomaterials applied under wet conditions such as guided bone regeneration membranes.

关键词： bioinspiration heterogeneous crosslink-and-hydration dual-scale network nanocomposite membrane wet mechanical properties guided bone regeneration

Exploration and Practice of the Digital Transformation and Upgrading Paths for Civil Engineering Majors

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Journal of Contemporary Educational Research 2024年第7期8卷 30-34页

作者： Yanan Fu Jinhui Zhou Xinna Zhu Jianhua zou School of Civil Engineering Chongqing Three Gorges UniversityChongqing 404100China

This article examines the pathway to digital transformation and upgrading in undergraduate institutions,using the civil engineering program at Chongqing Three Gorges University as a case study,focusing on six key areas:developing a high-quality digital talent training program for civil engineering;assembling diverse resources to create a digital,multi-scenario open learning environment that encompasses teaching,research,and practical training for civil engineering undergraduates;piloting innovative digital teaching models for civil engineering undergraduates;crafting a new model for digital resource provision,utilizing self-developed and specialized resources;devising assessment methods and ongoing improvement strategies based on the achievement of students’digital competencies;and devising a new,three-dimensional,multi-modal teaching evaluation system through intelligent data capture and analysis.

关键词： Digital transformation Civil engineering Local undergraduate institutions

A Fractal Study on Brittle-Ductile Transition forTi-24Al-11Nb Alloy

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Journal of Materials Science & Technology 1995年第5期11卷 340-344页

作者： CHEN, GL WANG, yd HUANG, yd SUN, ZQ YANG, WY Beijing Univ of Science and Technology Beijing China

The mechanical behaviours of Ti-24Al-11Nb alloy in the brittle-ductile transition (BOT) have been investigated by using three-point bending tests. The temperature dependence of the fractal dimensions and fractal characterization of fracture surfaces are presented. The probable mechanism controlling BDT of intermetallic alloys are proposed according to fractal ***. it is found that there is a positive relationship between the fractal dimension and fracture toughness in BDT for Ti-24Al-11Nb

关键词： Al Ti A Fractal Study on Brittle-Ductile Transition forTi-24Al-11Nb Alloy OO

THE DEFECT ITERATION OF THE FINITE ELEMENT FOR ELLIPTIC BOUNDARY VALUE PROBLEMS AND PETROV-GALERKIN APPROXIMATION

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Journal of Computational Mathematics 1998年第2期16卷 152-164页

作者： Gao, JB Yang, yd Shih, TM Huazhong Univ Sci & Technol Dept Math Wuhan 430074 Peoples R China Guizhou Normal Univ Dept Math Guiyang 550001 Peoples R China Hong Kong Polytech Univ Dept Math Appl Hong Kong Peoples R China

In this paper we introduce a Petrov-Galerkin approximation model to the solution of linear and semi-linear elliptic boundary value problems in which piecewise quadratic polynomial space and piecewise linear polynomial space are used as the shape function space and the test function space, respectively. We prove that the approximation order of the standard quadratic finite element can be attained in this Petrov-Galerkin model. Based on the so-called 'contractivity' of the interpolation operator, we further prove that the defect iterative sequence of the linear finite element solution converge to the proposed Petrov-Galerkin approximate solution.

关键词： Petrov-Galerkin approximation defect iteration correction interpolation operator

Studies on monodispersed colloidal particles of doped yttrium compounds

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Chinese Journal of Chemistry 1995年第3期13卷 199-206页

作者： DENG, HM XU, Y GU, yd FUDAN UNIV ANAL & MEASUREMENT RES CTRSHANGHAI 200433PEOPLES R CHINA FUDAN UNIV DEPT CHEMSHANGHAI 200433PEOPLES R CHINA

Monodispersed particles of doped yttrium basic carbonates were prepared at aging at elevated temperature corresponding salts solutions in the presence of urea. Coprecipitation in mixed solutions of yttrium, lanthanum and neodymium salts under similar experimental conditions yielded composite particles of basic carbonates. The content of the three metals in the solids followed closely the initial composition of the reacting solutions. On calcination all prepared solids converted to their corresponding oxides while retaining their particle morphology. The so-prepared powders were characterized by various techniques.

关键词： YTTRIUM COMPOUNDS MONODISPERSED PARTICLES UREA DECOMPOSITION

Synthesis of Dibenzo-sulfur-heterocycles through Reaction of Diphenyl-type Compounds with Elemental Sulfur over USY Zeolite

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Chinese Chemical Letters 1997年第10期8卷 849-852页

作者： Zuo, BJ Ma, yd Tian, Y Wang, QL SHANDONG UNIV DEPT CHEMJINAN 250100PEOPLES R CHINA

A series of dibenzo-sulfur-heterocycle compounds, such as phenothiazine, phenoxthine, thianthrene, thioxanthene and derivatives of dibenzothiophene were synthesized with satisfactory yields through reaction of the cor... 详细信息

关键词： over USY type Synthesis of Dibenzo-sulfur-heterocycles through Reaction of Diphenyl-type Compounds with Elemental Sulfur over USY Zeolite