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Enhancing Suppression of Chain Transfer via Catalyst Structural Evolution in Ethylene(Co)Polymerization

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Chinese Journal of Chemistry 2023年第12期41卷 1509-1516页

作者： Beihang ding Lihang Jiang Xiaohui kang Shengyu Dai Institutes of Physical Science and Information Technology Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education Anhui University Hefei Anhui 230601 China College of Pharmacy Dalian Medical University Dalian Liaoning 116044 China School of Chemical and Environmental Engineering Anhui Polytechnic University Wuhu Anhui 241000 China

Usually,the aniline-based late-transition-metal catalysts often require bulky steric substituents on both sides of the ortho-aryl position to achieve efficient suppression of chain transfer in ethylene *** this contribution,we demonstrated thatα-diimine catalysts based on naphthylamine with only one bulky ortho-aryl substituent also demonstrated excellent capabilities to suppress the chain ***,a class ofα-diimine nickel and palladium complexes with only one o-aryl-dibenzhydryl or o-aryl-dibenzosuberyl substituent were synthesized and ***,the as-prepared naphthylamine-based nickel catalysts demonstrated outstanding activities(up to 13.02×106 g·mol–1·h–1)and yielded lightly branched(16-40/1000C)polyethylenes with very high molecular weights(445.8-854.3 kg/mol)in ethylene *** comparison,the corresponding palladium catalysts showed moderate activities(level of 104-105 g·mol–1·h–1),generating moderately branched(47-78/1000C)polyethylenes with moderate molecular weights(21.6-82.0 kg/mol).Moreover,the palladium catalysts could also copolymerize ethylene and methyl acrylate(MA),albeit in low activities(level of 103 g·mol–1·h–1),providing E-MA copolymers with low to moderate molecular weights(1.4-16.3 kg/mol)and a moderate level of incorporation ratio(2.4-7.4 mol%)and branching density(53-84/1000C).As compared with aniline-based nickel and palladium catalysts,the naphthylamine-based catalysts displayed a superior ability to suppress the chain transfer reactions and could give access to(co)polymers with orders of magnitude higher molecular weight in ethylene(co)polymerization.

关键词： α-Dimine catalysts Chain transfer High molecular weight Naphthylamine-based catalysts Ethylene(co)polymerization Copolymers Homogeneouscatalysis Conformation

Face stability analysis of large shield-driven tunnel in rock-soil interface composite formations

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Underground Space 2022年第6期7卷 1021-1035页

作者： Xiaobin ding kang Li Yuxuan Xie Shuzhuo Liu School of Civil Engineering and Transportation South China University of TechnologyGuangzhou 510641China Guangdong Provincial Key Laboratory of Modern Civil Engineering Technology South China Institute of Geotechnical EngineeringGuangzhou 510650China

A new 3D log-spiral model(LS-M model)is proposed to determine the minimal support pressure on the tunnel face of a large shielddriven tunnel in rock-soil interface(RSI)composite *** the proposed LS-M model,we define the RSI angle ω and use a new approach to calculate the equivalent tunnel face area,which provides a collapse zone with more realistic geometry than the traditional wedge *** it has acceptable accuracy with simpler implementation than limit equilibrium *** with previous studies and 3D numerical analysis,it indicates that:(i)the LS-M results agree well with others in full-soil formations on the variation patterns of minimum support pressure and stability coefficients N_(c) and N_(γ);(ii)the critical RSI angle ω_(cr),which is predominantly influenced by soil cohesion,increases with the soil property values;(iii)the limit support pressure starts to increase with ω only when ω>ω_(cr);(iv)the peak support pressure occurs at lower C/D with a lower ω;(v)ω can only affect stability coefficients N_(c) and N_(γ) when ω and the friction angle are relatively small,while N_(s) is substantially influenced by RSI angle ω.

关键词： Tunnel Stability Limit support pressure RSI composite formations 3D failure mechanism

Global warming weakening the inherent stability of glaciers and permafrost

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Science Bulletin 2019年第4期64卷 245-253页

作者： Yongjian ding Shiqiang Zhang Lin Zhao Zhongqin Li Shichang kang State Key Laboratory of Cryospheric Science Northwest China Ecological Environment and Resource Research Institute Chinese Academy of Sciences Key Laboratory of Ecohydrology of Inland River Basin Chinese Academy of Sciences University of Chinese Academy Sciences Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity Northwest University College of Urban and Environmental Sciences Northwest University State Cryosphere Monitor and Research Station Northwest China Ecological Environment and Resource Research Institute Chinese Academy of Sciences State Glacier Monitor and Research Station Northwest China Ecological Environment and Resource Research Institute Chinese Academy of Sciences

The Cryosphere has been undergoing a worldwide retreat, as seen in the decrease in the areal extent and volume of glaciers and in the areal extent of permafrost. This paper presents a systematic examination of the inherent stability changes of glaciers and permafrost caused by warming. Various study results suggest that over the past 30 years, the internal temperature of glaciers and permafrost exhibits an overall accelerating warming trend. The warming rate peaked in the mid-2000s and slowed slightly for several years afterward. In recent years, however, the warming rate has seemed to pick up again. The warming of glaciers and permafrost has exerted great impact on their stability, displayed as intensified melting,increased glacier surging, enlargement of supraglacial lakes, and increased permafrost *** without a future temperature increase, some glaciers will continue to shrink, and the number of surging glaciers will increase. The transition from low-temperature to high-temperature permafrost is a noticeable warning sign of a comprehensive degradation of permafrost. These results indicate that‘‘warming" glaciers and permafrost will exert significant impacts on the hydrology, ecology, and stability of engineering in cold regions.

关键词： Warming Englacial temperature Permafrost temperature Internal thermal state Stability

Effects of Area Discontinuity at Nozzle Inlet on the Characteristics of Self-resonating Cavitating Waterjet

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Chinese Journal of Mechanical Engineering 2016年第4期29卷 813-824页

作者： LI Deng kang Yong ding Xiaolong WANG Xiaochuan FANG Zhenlong School of Power and Mechanical Engineering Wuhan University Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan University Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign

The current research on self-resonating cavitating waterjet（SRCW） mainly focuses on the generation mechanism and structure *** relating to the influences of disturbances at nozzle inlet on the characteristics of the jet are rarely *** order to further improve the performance of SRCW,effects of area discontinuity（enlargement and contraction） are experimentally investigated using three organ-pipe *** pressure oscillation peak and amplitude as well as aggressive erosion intensity of the jet are used to evaluate the *** results reveal that area enlargement and contraction affect the peak differently,depending on the inlet pressure,nozzle geometry,and standoff distance;while area contraction always improves the amplitude regardless of these *** inlet pressures of 10 MPa and 20 MPa,area discontinuity improves the peak at almost all the testing standoff distances,while this only happens at smaller standoff distances with the inlet pressure increased to 30 *** capability of area discontinuity for improving the amplitude is enhancing with increasing inlet ***,the cavitation erosion ability of the jet can be largely enhanced around the optimum standoff distance,depending on the type of area discontinuity and nozzle geometry.A preliminary analysis of the influence of area discontinuity on the disturbance waves in the flow is also *** proposed research provides a new method for effectively enhancing the performance of SRCW.

关键词： area discontinuity self-resonating cavitating waterjet(SRCW) organ-pipe nozzle pressure oscillation cavitation erosion

A networked remote sensing system for on-road vehicle emission monitoring

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Science China(Information Sciences) 2017年第4期60卷 224-231页

作者： Yu kang Yan ding Zerui LI Yang CAO Yunbo ZHAO State Key Laboratory of Fire Science University of Science and Technology of China Department of Automation University of Science and Technology of China Institute of Advanced Technology University of Science and Technology of China Chinese Research Academy of Environmental Sciences College of Information Engineering Zhejiang University of Technology

Vehicle emissions are a major source of urban air pollution, and therefore a real-time monitoring system can be very useful in analyzing such emission and consequently assisting the policy making process. In this work we discuss the principle and structure of three different types of remote sensing detectors, and also the key techniques to establish a networked remote sensing monitoring system. We finally conclude this paper with data analysis from some preliminary experiments.

关键词： networked system remote sensing vehicle emissions

数字化精准全膝关节置换与传统置换方法的短期效果对比

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中国组织工程研究 2025年第21期29卷 4521-4528页

作者：王宇宁朱浩天刘康丁焕文严瀚华南理工大学广东省广州市510006 广州市第一人民医院广东省广州市510180

背景:传统全膝关节置换手术在术前的准备有限,作者提出基于计算机仿真和3D打印技术的数字化精准全膝置换方法,旨在通过充分的术前设计来提升置换效果。目的:利用计算机仿真和个性化手术导板建立数字化精准全膝关节置换方法,比较新方法... 详细信息

背景:传统全膝关节置换手术在术前的准备有限,作者提出基于计算机仿真和3D打印技术的数字化精准全膝置换方法,旨在通过充分的术前设计来提升置换效果。目的:利用计算机仿真和个性化手术导板建立数字化精准全膝关节置换方法,比较新方法和传统方法的临床效果。方法:回顾性分析97例全膝关节置换患者的临床资料,根据手术方法将患者分为2组,对照组(n=48)采取传统方式进行全膝关节置换手术,使用传统胶片模板;观察组(n=49)采用数字化精准全膝置换方法进行手术,使用计算机辅助技术选定假体尺寸型号。比较两组患者的手术时间、术中出血量、术前及术后美国特种外科医院膝关节评分以及股骨力线和膝关节面线夹角和胫骨角、髋膝踝角与标准角度的差值。结果与结论:(1)两组患者术前性别、年龄、体质量指数、美国特种外科医院膝关节评分,以及胫骨角、股骨力线和膝关节面线夹角、髋膝踝角与标准角度的差值相比差异均无显著性意义(P> 0.05);(2)与对照组比较,观察组手术时间缩短、出血量减少;两组术后3个月膝关节美国特种外科医院膝关节评分对比术前均显著升高(P> 0.05),且术后3个月观察组评分高于对照组(P> 0.05);(3)两组之间胫骨角、股骨力线和膝关节面线夹角、髋膝踝角与标准角度的差值相比差异均有显著性意义,观察组优于对照组(P <0.05);(4)观察组股骨假体预测准确率为94%,对照组为58%;胫骨假体预测准确率为96%,对照组为62%;(5)提示数字化精准全膝关节置换相较传统全膝关节置换的手术时间更短、出血量更少、术后膝关节功能评分和力线恢复更好,具有良好的短期临床效果。

关键词： 3D打印全膝关节置换个性化截骨导板假体预测计算机仿真下肢力线

Direct transformation of fossil carbon into chemicals: A review

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Journal of Energy Chemistry 2023年第2期77卷 247-268,I0007页

作者： Jingyuan Fan kang Gao Peng Zhang Yuying Dang Yuxiao ding Bingsen Zhang Lanzhou Institute of Chemical Physics Chinese Academy of SciencesLanzhou 730000GansuChina Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016LiaoningChina

Despite the long tradition of fossil carbon(coal,char,and related carbon-based materials)for fueling mankind,the science of transforming them into chemicals is still demandingly progressing in the current energy scenario,especially when considering its responsibilities to the global climate ***,there are four routes of preparing chemicals directly from fossil carbon,including hydrogasification,gasification,direct liquefaction,and oxidation,in the macroscope of gas-solid reaction(hydrogasification and gasification)and liquid-solid reaction(direct liquefaction and oxidation).When the study goes to microscale,the gas-solid reaction can be considered as the reaction between the severe condensed radicals and gas,while the liquid-solid reaction is the direct reaction between the radical and the *** have a full overview of the area,this review systematically summarizes the main factors in these processes and shows our own perspectives as follows,(ⅰ)stabilizing the free radicals generated from coal and then directly converting them has the highest efficiency in coal utilization;(ⅱ)the research on the self-catalytic process of coal structure will have a profound impact on the direct preparation of chemicals from fossil *** discussions are also proposed to guide the future study of the area into a more sustainable direction.

关键词： Fossil carbon Coal-based carbon materials Direct fossil carbon conversion processes Hydrogasification Gasification Direct liquefaction Oxidation

Flexible Polydimethylsiloxane Composite with Multi-Scale Conductive Network for Ultra-Strong Electromagnetic Interference Protection

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Nano-Micro Letters 2023年第1期15卷 293-306页

作者： Jie Li He Sun Shuang-Qin Yi kang-kang Zou Dan Zhang Gan-Ji Zhong ding-Xiang Yan Zhong-Ming Li College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065People’s Republic of China School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065People’s Republic of China

Highly conductive polymer composites(CPCs) with excellent mechanical flexibility are ideal materials for designing excellent electromagnetic interference(EMI) shielding materials,which can be used for the electromagnetic interference protection of flexible electronic *** is extremely urgent to fabricate ultra-strong EMI shielding CPCs with efficient conductive *** this paper,a novel silver-plated polylactide short fiber(Ag@PL ASF,AAF) was fabricated and was integrated with carbon nanotubes(CNT) to construct a multi-scale conductive network in polydimethylsiloxane(PDMS) *** multi-scale conductive network endowed the flexible PDMS/AAF/CNT composite with excellent electrical conductivity of 440 S m-1and ultra-strong EMI shielding effectiveness(EMI SE) of up to 113 dB,containing only 5.0 vol% of AAF and 3.0 vol% of CNT(11.1wt% conductive filler content).Due to its excellent flexibility,the composite still showed 94% and 90% retention rates of EMI SE even after subjected to a simulated aging strategy(60℃ for 7 days) and 10,000 bending-releasing *** strategy provides an important guidance for designing excellent EMI shielding materials to protect the workspace,environment and sensitive circuits against radiation for flexible electronic devices.

关键词： Flexible conductive polymer composites Silver-plated polylactide short fiber Carbon nanotube Electromagnetic interference shielding Multi-scale conductive network

Effect of Y and Gd content on the microstructure and mechanical properties of Mg-Y-RE alloys

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Journal of Magnesium and Alloys 2019年第2期7卷 345-354页

作者： kang Luo Liang Zhang Guohua Wu Wencai Liu Wenjiang ding National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composite School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240PR China

In the application of WE43,it is found that Y_(2)O_(3)inclusion formed in the process of casting seriously reduced the mechanical properties of the *** reduction of the mechanical properties is even more distinct when it comes to the application in the thin walled complex-precision *** order to decrease the Y_(2)O_(3)inclusions,Gd element was used to replace part of the Y element in Mg-Y-RE series *** effect of Y content(Mg-x Y-1Gd-2Nd-0.5Zn-0.5Zr)and Y/Gd ratio(Mg-x Y-(5-x)Gd-2Nd-0.5Zn-0.5Zr)on the microstructure and mechanical properties of Mg-Y-RE alloys were investigated in this *** decreasing Y content,the grain size of the alloys increased,both ultimate tensile strength(UTS)and yield strength(YS)of alloys decreased *** part of Y content with Gd and keeping the total rare earth content unchanged,the low Y content Mg-2Y-3Gd-2Nd-0.5Zn-0.5Zr alloy showed the same mechanical properties as the high Y content Mg-4Y-1Gd-2Nd-0.5Zn-0.5Zr alloy at both room and elevated *** solution treatment at 525°C for 8 h and aging treatment at 225°C for 10 h,the UTS,YS and elongation(ε)of Mg-2Y-3Gd-2Nd-0.5Zn-0.5Zr alloy reached 281.7 MPa,198 MPa and 11.1%at room temperature,and 216.7 MPa,171.6 MPa and 16.1%at 250°*** new low Y content Mg-2Y-2Nd-3Gd-0.5Zn-0.5Zr alloy is expected to replace the high Y content WE43 alloys,which can be used in the complex thin-walled parts of aviation products.

关键词： Mg-Y-RE alloy Microstructure Mechanical property Y/Gd ratio,Heat treatment