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Investigating the Nucleation Effect of DMDBS on Syndiotactic Polypropylene from the Perspective of Chain Conformation

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Chinese Journal of Polymer Science 2020年第12期38卷 1355-1364页

作者： Xin-Xin Wang jian-jun yi Li Wang Yuan Yuan Jia Chun Feng State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200433China Laboratory for Synthetic Resin Research Petrochina Petrochemical Research Institute Beijing 102200China

The mechanism of nucleating agents(NAs)accelerating the crystallization of semi-crystlline polymers has received continuous attention due to the extreme importance in academic research and industry *** this work,the nucleation effect and probable mechanism of 1,3.2,4 bis(3,4-dimethylbenzylidene)sorbitol(DMDBS)on promoting the crystallization of syndiotactic polypropylene(sPP)was systematically *** results showed that DMDBS could significantly accelerate the crystallization process and did not change the crystalline form of *** in situ infrred spectra recorded in the crystallization process showed that in pristine sPP the tttt conformers decreased and the tgg conformers increased *** sPP/DMDBS system,DMDBS could promote the increase of tgg conformers rather than the decrease of tttt *** further analysis by 2D-IR spectra revealed that ttgg conformers increased prior to the decrease of tttt conformers in the sPP/DMDBS system comparing with pristine *** that ttgg conformers were basic elements of helical conformation of Form I crystal for sPP,we proposed a probable nucleation mechanism of DMDBS for sPP:DMDBS could stabilize the ttgg conformers which induced these ttgg conformers to pre-orientate and aggregate into helical conformation sequences as initial nuclei quickly and early to promote the sPP *** work provides some new insights into the nucleation mechanism of NAs for sPP.

关键词： Syndiotactic polypropylene Nucleating agent Crsallization Conformation

CHARACTERIZATION OF IMPACT POLYPROPYLENE COPOLYMERS BY SOLVENT FRACTIONATION

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Chinese Journal of Polymer Science 2012年第1期30卷 122-129页

作者： Xiao-ying Lu jian-jun yi Shang-tao Chen Feng-hua Zu Rong-bo Li Petrochina-Petrochemical Research Institute Being 100195 China

The compositional heterogeneity of two impact polypropylene copolymers（IPCs） was studied by a combinatory investigation of temperature rising elution fractionation（TREF） and solvent *** chain structures and composition of fractions obtained from solvent fractionation were examined in *** TREF results shows that there are much more E-P segmented copolymer and more uniform distribution of ethylene sequence in IPC-1,which is responsible for its better comprehensive mechanical *** fractions from hexane and heptane are ethylene-propylene rubber phase and E-P block copolymers *** result of solvent fractionation method also shows that custom hexane or heptane extractions can not extract the E-P copolymer completely.

关键词： Fractionation Impact polypropylene copolymer Composition Chain structure

Invasion and control of water hyacinth (Eichhornia crassipes)in China

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2006年第8期7卷 623-626页

作者： CHU jian-jun DING yi ZHUANG Qi-jia School of Life Science and Biotechnology Shanghai Jiao Tong University Shanghai 200240 China

By the time of primary 21st century, water hyacinth had become a serious environmental problem in China. Water hyacinth contributes to the major part of ecological hazards from the invasion of foreign plant species, which is estimated about USD 7 billion a year in values. In the past 10 years, herbicides glyphosate, 2,4-D and paraquat have been used in controlling water hyacinth in China. Al- though the herbicides provided effective control on the weed in some areas, they could not provide the sustainable inhibition on the weed population, while would lead to pollution on water at various levels. At present, the herbicide application on water hyacinth is forbidden in many areas of China such as Shanghai. In this situation, the asexual reproduction inhibitor, KWH02, was invented for controlling water hyacinth and it provided about 70% of growth inhibition without any risk of dead plant pollution. It has been about 10 years for bio-control of water hyacinth in China. Works focused on mainly the efficacy and safety of the utilization of foreign insects. Researches on microorganism herbicides to control water hyacinth were started and obtained primary achievements in recent years. Although there are different opinions on how to face the water hyacinth problem in China, it is accepted widely that the control methods should be high efficient and safe with low cost. Some practical measures for integrated management of water hyacinth are suggested.

关键词： Invasion Control Water hyacinth China

ADSORPTION OF TiCl_4 AND ELECTRON DONOR ON DEFECTIVE MgCl_2 SURFACES AND PROPYLENE POLYMERIZATION OVER ZIEGLER-NATTA CATALYST: A DFT STUDY

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Chinese Journal of Polymer Science 2013年第4期31卷 591-600页

作者： Rui-hua Cheng jun Luo Zhen Liu Jing-wen Sun Wei-huan Huang Ming-ge Zhang jian-jun yi 刘柏平 State Key Laboratory of Chemical Engineering East China University of Science and Technology Petrochemical Research Institute China National Petroleum Corporation

The formations of defective MgC12 surfaces, and subsequent adsorption of Ti species and electron donor, as well as propylene polymerization over the Ziegler-Natta catalyst have been investigated using density functional theory （DFT） method. Twelve possible support models of regular and defective MgC12 （110） and （100） surfaces were built. The individual adsorptions of titanium chlorides as mononuclear or dinuclear, and ethyl benzoate （EB） as electron donor, on these models were evaluated. The analysis of energies presented the cases of EB adsorption were generally more stable than titanium chlorides on both surfaces. Thus, EB as internal electron donor mainly prevented TIC14 from coordinating on the MgC12 surfaces where mostly non-stereospecific active sites could be formed. Exceptionally, A5 the site model with terminal Cl-vacancy on the MgC12 support, presented stronger adsorption of TiCl4 than that of EB on （110） surface. Since the TIC14 and ethyl benzoate （EB） would compete to adsorb on the support surface, it seems reasonable to assume that TIC14 might predominately occupy this site, which can act as the most plausible active site for propylene polymerization. The first insertion of propylene monomer into the A5 active site model showed that it exhibited good regioselectivity but poor stereospecificity in the absence of electron donor.

关键词： Supported Ziegler-Natta catalyst Propylene polymerization Defective MgC12 surfaces Electron donor Densityfunctional theory.

Cooperative enhancement of mechanical and tribological properties through tailoring TiN transition interface in boron nitride nanosheets reinforced copper composites

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Rare Metals 2024年第10期43卷 5202-5215页

作者： Zhong-Hua Li Liang Liu Xin You jian-Hong yi Rui Bao Ming-yi Zhu Song Lu jun-jun Pai Faculty of Materials Science and Engineering Kunming University of Science and Technology Key Laboratory of Advanced Materials of Yunnan Province Kunming University of Science and Technology

Strengthening interface bonding between boron nitride nanosheets(BNNS) and copper matrix is an essential prerequisite for exploiting a new generation of copper matrix composites(CMCs) with high strength and wear resistance. Herein, BNNS/Cu composites were fabricated by the powder metallurgy route, matrix-alloying(adding 1.0 wt% Ti) strategy was adopted to improve the interfacial wettability and strengthen interface adhesion. A typical "sandwich"-like multiply interface structure involving TiN transition layers, BNNS and Cu matrix had been well constructed through the rational heat treatment(900℃for 120 min). Additionally, nano-sized TiB whisker was in situ formed in the vicinity of the interface, it had linked the BNNS-Cu-TiN multiply interface, which played a role of "threading the needle" and significantly strengthened the multi-interfaces bonding. This specific interface structure was finely characterized, and the formation mechanism of solid-state interfacial reaction feature was proposed. The results demonstrated that the ultimate tensile strength(UTS) of BNNS/Cu-(Ti)-900℃ increased from 248 to 530 MPa(increased by 114%), and the coefficient of friction(COF) decreased from 0.51 to 0.28 than pure Cu. This work highlights the importance of interface configuration design, which contributes to the development of CMCs with prominent comprehensive properties.

关键词： Boron nitride nanosheets Copper matrix composites Interface structure Mechanical and frictional properties

Permanent lining castable with low bulk density and thermal conductivity:bauxite castable for tundish obtained by adding pearlescent sand

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Journal of Iron and Steel Research International 2024年第3期31卷 634-646页

作者： yi Wang jian Yang Bao Wang Hai-jun Zhang Juan Han Pei-yan Pei Wen-long Lv jian-an Zhou The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081HubeiChina Wuhan Research Institute of Metallurgical Construction MCCWuhan 430081HubeiChina

The low thermal conductivity and light mass of castables for tundish permanent linings are crucial for minimizing the heat loss of molten *** consideration of the low bulk density and thermal conductivity of pearlescent sand,the thermal insulation performance of castables was attempted to be improved by adding pearlescent *** sand was modified to prevent the strength of its porous structure from *** modification mechanism of pearlescent sand and the effect of pearlescent sand on the performance of bauxite castables were *** results suggested that the addition of the modified pearlescent sand significantly raised the apparent porosity and decreased the bulk density of bauxite *** 1000℃,the bulk density of more than 60%of the modified pearlescent sand-bauxite castable was only 2.03 g/cm^(3).The mechanical properties and thermal shock resistance of the modified pearlescent sand-bauxite castable were inferior to those of conventional bauxite castable but were adequate to meet the use conditions of casta-bles for tundish permanent *** high temperatures of 200-800℃,the thermal conductivity of more than 60%of the modified pearlescent sand-bauxite castable was smaller than that of conventional bauxite *** addition of the modified pearlescent sand can greatly reduce the thermal conductivity and bulk density of bauxite castable.

关键词： Pearlescent sand-Hydrophobic modification Bauxite castable Thermal insulation performance Mechanical property

Coral-shaped and Core-Shell Structure Copolyethylene Nanocomposites Particles Prepared by in situ Coordination Polymerization

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Chinese Journal of Polymer Science 2015年第12期33卷 1650-1660页

作者： Jing Wang Hong-ming Li jiang-ping Guo 黄启谷 jian-jun yi Yun-fang Liu Ke-jing Gao Wan-tai Yang State Key Laboratory of Chemical Resource Engineering Key Laboratory of Carbon Fiber and Functional PolymersMinistry of Education Beijing University of Chemical Technology Lab for Synthetic Resin Research Institution of Petrochemical Technology China National Petroleum Corporation

The example of the preparation ofnano- and micro-scaled, coral-shaped and core-shell topological morphology of copolyethylene particles promoted by the novel heterogeneous non-metallocene catalyst （m-CH3PhO）TiC13/carbon nanotubes （CNTs） was reported. Mass fraction of titanium component of the catalyst was 4.0 wt% determined by ICP analysis. The catalyst system can effectively catalyze polymerization of ethylene and eopolymerization of ethylene with 1-hexene. Morphological examination of the obtained polymer particles was carried out by scanning electron microscope （SEM） and high resolution transmission electron microscope （HR-TEM） technique. The results revealed that the morphology of the nascent copolyethylene particles looked like coral shape with size in micro-scaled and featured the core-shell structure consisting of CNTs as the core and copolyethylene as the shell.

关键词： Catalysts Composites Copolymers.

Multisensory Conflict Impairs Cortico-Muscular Network Connectivity and Postural Stability: Insights from Partial Directed Coherence Analysis

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Neuroscience Bulletin 2024年第1期40卷 79-89页

作者： Guozheng Wang yi Yang Kangli Dong Anke Hua jian Wang jun Liu Key Laboratory for Biomedical Engineering of Ministry of Education College of Biomedical Engineering&Instrument ScienceZhejiang UniversityHangzhou 310058China Taizhou Key Laboratory of Medical Devices and Advanced Materials Research Institute of Zhejiang University-TaizhouTaizhou 318000China Department of Sports Science College of EducationZhejiang UniversityHangzhou 310058China Center for Psychological Science Zhejiang UniversityHangzhou 310058China

Sensory conflict impacts postural control,yet its effect on cortico-muscular interaction remains *** aimed to investigate sensory conflict's influence on the cortico-muscular network and postural *** used a rotating platform and virtual reality to present subjects with congruent and incongruent sensory input,recorded EEG(electroencephalogram)and EMG(electromyogram)data,and constructed a directed connectivity *** results suggest that,compared to sensory congruence,during sensory conflict:(1)connectivity among the sensorimotor,visual,and posterior parietal cortex generally decreases,(2)cortical control over the muscles is weakened,(3)feedback from muscles to the cortex is strengthened,and(4)the range of body sway increases and its complexity *** results underline the intricate effects of sensory conflict on cortico-muscular *** the sensory conflict,the brain adaptively decreases the integration of conflicting *** this integrated information,cortical control over muscles may be lessened,whereas the muscle feedback may be enhanced in compensation.

关键词： Cortico-muscular interaction Postural control Virtual reality Electroencephalogram Electromyography Sensory integration

Study of primordial deuterium abundance in Big Bang nucleosynthesis

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Nuclear Science and Techniques 2024年第3期35卷 208-215页

作者： Zhi-Lin Shen jian-jun He Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Institute of Radiation Technology Beijing Academy of Science and TechnologyBeijing 100875China

Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early *** these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent *** date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational *** this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium *** found that the reaction rate uncertainties of the four reactions d(d,n)^(3)He,d(d,p)t,d(p,γ)^(3)He,and p(n,γ)d had the largest influence on the calculated D/H ***,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) He *** the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.

关键词： Big Bang nucleosynthesis Abundance of deuterium Reaction cross section Reaction rate Monte Carlo method