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Deactivation Effect Caused by Catalyst-Cocatalyst Pre-contact in Propylene Polymerization with MgCl2-supported Ziegler-Natta Catalyst

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Chinese Journal of Polymer Science 2019年第10期37卷 1023-1030,I0005页

作者： Zhen Zhang Bai-Yu jiang Biao Zhang zhi-Sheng Fu zhi-Qiang Fan Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Propylene slurry polymerization with a MgCl2-supported Ziegler-Natta catalyst containing internal electron donor was conducted after different durations of pre-contact of the catalyst with triethylaluminum cocatalyst. The number of active centers([C*]/[Ti])was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and measuring sulfur content in the polymer. The pre-contact treatment caused selective deactivation of a part of active centers with low stereoselectivity and much lower activity in the initial stage of polymerization as compared with the polymerization run without the pre-contact stage. The active center concentration and polymerization activity decreased with prolonging of the pre-contact stage. The proportion of stereoselective active centers was increased by prolonging the pre-contact stage, so the isotacticity of produced polypropylene was enhanced. Release of active centers through catalyst particle fragmentation was significantly retarded, and the polymerization rate curve changed from decay type to induction type by the precontact treatment. In the induction period both non-stereoselective and stereoselective active centers were released and activated, resulting in gradual reduction of the polymer’s isotacticity in the first 5-10 min of polymerization. Selective deactivation of non-stereoselective active centers also took place in propylene polymerization using the catalyst without pre-contacting with the cocatalyst. In this case, the polymerization rate decayed with time after a short induction period of 2-5 min. Over reduction of the active center precursors with low stereoselectivity by triethylaluminum was considered as the reason for their deactivation during the pre-contact or the polymerization processes.

关键词： Propylene Polymerization Supported Ziegler-Natta catalyst Cocatalyst Pre-contact

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Phase equilibrium and microstructure of topological AdS black holes in massive gravity

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Chinese Physics C 2022年第8期46卷 230-243页

作者： Fang Liu Yun-zhi Du Ren Zhao huai-Fan Li Department of Physics Shanxi Datong UniversityDatong 037009China Insitute of Theoretical Physics Shanxi Datong UniversityDatong 037009China

In order to clearly understand the gravitational theory through the thermal properties of the black hole,it is important to further investigate the first-order phase transition of black *** this paper,we adopt different conjugate variables(P~V,T~S,C_(1)~c_(1),and C_(2)~c_(2)) and apply Maxwell's equal-area law to study the phase equilibrium of a topological black hole in massive *** condition and latent heat of phase transition are displayed as well as the coexistent curve of *** result shows that the phase transition of this system is the high/low electric potentials one,not only the large/small black holes *** also analyze the effect of the model's parameters on phase *** we introduce a new order parameter to probe the microstructure of this *** work will provide the theoretical basis to study the phase structure of topological black holes in massive gravity and to further explore the gravitational theory.

关键词： black hole first-order phase transition Maxwell's equal-area law microstructure

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Experimental investigation of the flow characteristics of jet pumps for zero flow-ratio conditions

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Journal of Hydrodynamics 2023年第6期35卷 1146-1156页

作者： Yun-zhi Liang Jiong Wang Zu-ti Zhang Bin Ji huai-yu Cheng Xin-ping Long Key Lab of Jet Theory and New Technology of Hubei Province Wuhan UniversityWuhan430072China School of Power and Mechanical Engineering Wuhan UniversityWuhan430072China State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China

Experimental research was conducted on the performance curves and the cavity evolution for different flow and geometric parameters in jet pumps for zero flow ratio(ZFR)*** pressure ratio,Pr,flow ratio,qr,were used in place of the conventional performance parameters h,q,to characterize the jet pump flow performance.A super cavitation cavity in the jet pump was observed to fill most of the flow channel,which hindered further increases of the flow rate and increased qr to one,thus,created a critical point on the new P_(r)-q_(r)^(2)*** the critical point,P_(r)was proportional to q_(r)^(2)with a coefficient that was much more sensitive to the area ratio than the relative throat length and the diffusion *** the critical point,the flow rate reached its maximum,the limiting flow rate,which only depended on the total inlet pressure and the area *** total inlet pressure was proportional to the square of the limiting flow rate with a flow coefficient that was only a quadratic function of the area ratio.

关键词： Jet pump performance curve zero flow-ratio super-cavitation

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K-Factors and Hamilton Cycles in Graphs

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Acta Mathematica Sinica,English Series 2007年第2期23卷 309-312页

作者： zhi Guo WANG Zhen jiang ZHAO College of Mathematics and Information Sciences He'nan University Kaifeng 475001 China P. O. Box 5122 No. 21 Beijin9 100094 China

We discuss k-factors and Hamiltonian Graphs in graph theory. We prove a general version of the conjecture by R. Haggkvist; as a result, we prove two extended versions of two well-known theorems due to O. Ore and B. Ja... 详细信息

关键词： k-factor 2-connected graph Hamilton cycle

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Plugging property and displacement characters of a novel high-temperature resistant polymer nanoparticle

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Petroleum Science 2022年第1期19卷 387-396页

作者： zhi-Yong Wang Mei-Qin Lin huai-Ke Li Zhao-Xia Dong Juan Zhang Zi-Hao Yang Unconventional Petroleum Research Institute China University of Petroleum(Beijing)Beijing102249People's Republic of China Oilfield Chemicals R&D Institute China Oilfield Services LimitedLangfang065201People's Republic of China China University of Geosciences(Beijing) Beijing100083People's Republic of China

The goal of the research was to investigate the profile control and oil displacement characteristics of the polymer nanoparticles after high temperature *** displacement parameters showed considerable influence on the plugging effect of the high-temperature swelled polymer nanoparticles,such as the core permeability,concentration of nanoparticles in the suspension,swelling time and swelling temperature,which makes it flexible to control the plugging effect by controlling displacement experiments *** results show that polymer nanoparticles dispersion system with a concentration of 500 mg/L is suitable for cores plugging with a permeability of 30×10^(-3)-150×10^(-3)μm^(2),even after aging at 150℃ for three *** shunt flow experiments show that when the displacement factors are optimal values,the polymer nanoparticles after high temperature swelling to plug the high-permeability layer selectivity and almost do not clog the low-permeability *** recovery of homogeneous artificial core displacement experiment and a heterogeneous double-tube cores model are increased by 20%and 10.4%on the basis of water *** polymer nanoparticles can be a great help for petroleum engineers to better apply this deep profile control and flooding technology.

关键词： Polymer nanoparticles High temperature resistance Plugging property EOR

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Growth of Ag/g-C_(3)N_(4) nanocomposites on nickel foam to enhance photocatalytic degradation of formaldehyde under visible light

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Journal of Environmental Sciences 2024年第3期137卷 432-442页

作者： Ze Wang zhi Huang jiang Yu Xiao Shao Weidong Peng Jie Yu Yinying jiang Department of Environmental Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Institute of New Energy and Low Carbon Technology Sichuan UniversityChengdu 610065China School of Agriculture and Environment University of Western AustraliaPerth 6907Western AustraliaAustralia Yibin Institute of Industrial Technology Sichuan UniversityYibin 644000China

Formaldehyde is a pollutant that significantly affects the indoor air ***,conventional remediation approaches can be challenging to deal with low-concentration formaldehyde in an indoor *** this study,Photocatalysts of Ag/graphitic carbon nitride(g-C_(3)N_(4))/Ni with 3D reticulated coral structure were prepared by thermal polymerization and liquid phase photo-deposition,using nickel foam(NF)as the *** demonstrated that when the Ag concentration was 3%,and the relative humidity was 60%,the Ni/Ag/g-C_(3)N_(4)showed the maximum degradation rate of formaldehyde at 90.19%under visible light irradiation,and the formaldehyde concentration after degradation was lower than the Hygienic standard stated by the Chinese *** porous structure of Ni/Ag/g-C_(3)N_(4)and the formation of Schottky junctions promoted the Adsorption efficiency and degradation of formaldehyde,while the nickel foam carrier effectively promoted the desorption of degradation ***,the degradation rate was only reduced by3.4%after 16 recycles,the three-dimensional porous structure extended the lifetime of the *** study provides a new strategy for the degradation of indoor formaldehyde at low concentrations.

关键词： Graphitic carbon nitride(g-C_(3)N_(4)) Nickel foam(NF) Ag Formaldehyde Photocatalysis

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Saturation throughput analysis of RTS/CTS scheme in an error-prone WLAN channel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第12期10卷 1714-1719页

作者： Xiang-yu PENG Le-tian jiang Guo-zhi XU Department of Electronic Engineering Shanghai Jiao Tong University Shanghai 200240 China

In this paper, a new three-dimensional Markov model is proposed for the estimation of saturation throughput of RTS/CTS (request to send/clear to send) scheme in an error-prone wireless local area network (WLAN) channel. The model takes account of the effect of bit error on all the frames, and station short and long retry limits. Saturation throughput was re-analyzed using the new Markov model and numerical results closely matched those from simulation, confirming the accuracy of the new model. Evaluation of the influence of different parameters on throughput showed that the saturation throughput is sensitive to channel bit error rates and packet length, especially in high bit error conditions.

关键词： Saturation throughput RTS/CTS Error-prone WLAN channel Markov model _ _

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Cladding of aluminum alloy 6061-T6 to mild steel by an electromagnetic tube bulging process: finite element modeling

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Advances in Manufacturing 2019年第1期7卷 73-83页

作者： zhi-Song Fan Su-Ting Huang jiang-Hua Deng School of Mechanical Engineering and Automation Fuzhou University Fuzhou 350116 People's Republic of China

Bimetal tubes have useful applications in various industries where service conditions demand more different requirements in the tube core than its outside surface. The recent use of electromagnetic forces to deform or join metallic workpieces at high speeds has undergone rapid growth for materials processing. However, to date, no sufficient systematic understanding of the underlying principles of a subsequent high-speed electromagnetic tube bulging process to manufacture bimetal tubes has been gained. In this work, magnetic pulse cladding of Al/Fe clad bimetal tubes was analyzed by finite element modeling (FEM) using ANSYS software. The validity of FEM analyses was first confirmed by experiments in terms of the deformed shape. Second, the effect of cladding parameters (such as axial feeding being the dominant factor in the multi-step process) on the bulging and thinning behavior of the Al clad tube was presented in detail. Both the numerical simulation and experimental results show that no more than 70% of the bulging-coil length is an appropriate amount for the feeding length to prevent defects from being introduced by non-uniform deformation in the transition zone of the Al clad tube. The distributions of the magnetic flux line, magnetic force, and plastic strain in different cladding steps were then analyzed. It was concluded that during the multi-step cladding process, there was an uneven distribution of the magnetic field force along the transition zone. Consequently, inharmonious plastic deformation behavior occurs, which results in a limited acceleration of the transition zone to a certain impact velocity.

关键词： Bimetal tubes Magnetic pulse cladding Finite element (FE) simulation Axial feeding

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Primary instabilities and bicriticality in fiber suspensions between rotating cylinders

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第9期8卷 1435-1442页

作者： WAN Zhan-hong SUN zhi-lin YOU Zhen-jiang Department of Hydrauhc and Ocean Engineering Zhejiang University. Hangzhou 310028 China School of Informatics and Engineering Flinders University of South Australia Adelaide SA 5001 Australia

The linear stability of fiber suspensions between two concentric cylinders rotating independently is studied. The modified stability equation is obtained based on the fiber orientation model and Hinch-Leal closure approximation. The primary instabilities and bicritical curves have been calculated numerically. The critical Reynolds number,wavenumber and wave speeds of fiber suspensions as functions of the aspect ratio,volume concentration of the fibers and the gap width of cylinders are obtained.

关键词： Fiber suspensions Primary instability Non-axisymmetric disturbances

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Structural Analysis of Water-soluble Polysaccharide PIP_1 Extracted from the Cultured Mycelium of Phellinus igniarius

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Chemical Research in Chinese Universities 2006年第6期22卷 708-711页

作者： WU Ming-jiang jiang De-zhi LIU Tie-mei ZHANG Li-ping School of Life Science Northeast Normal University Changchun 130024 P. R. China School of Life and Environment Science Wenzhou University Wenzhou 325035 P.R. China

Water-soluble crude polyseccharide（PIP） was extracted from cultured mycelium of the fungus Phellinus igniarius. After ethanol precipitation and sepharose CL-6B gel filtration, the fraction of PIP1 was obtained, which was shown to be a homogeneous polysaccharide by means of high-performance liquid chromatography. The structure of PIPt was determined by using several methods. C.,C analysis indicates that PIP1 is composed of the monosaccharides of glucose, galactose, and mannose. Their malar ratio is 3. 70： 4. 06： 1.00. The molar weight was estimated to be 17 kd via HPLC. IR, GC, partial hydrolysis with acid, pefiedate oxidation, Smith degradation, methylation, and GC-MS analysis were used for the structural analyses of PIP1. The results show that PIP1 has a small quantity of branch structure, The main glycosidic linkage of PIP1 has a β-configurafion. The main chain is made up of a large mass of glucose （ 1→3 ） and few mannose （ 1→4 ） ; the side chain is composed of glucose （ 1 →3 ） and galactose （ 1→6 ） ; the nonreduced end is composed of galactose and glucose. The side chains are branched at 6-0 of glucose（ 1→3,6） and mannose（1→4,6）. On an average, there are three branches among 20 residues. It is presumable that the existence of 1,3-linked Glc in the main and side chains is the main reason for its higher antitumor activity.

关键词： Phellinus igniarus Cultured mycelium Polysaccharide Structural analysis

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