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Microemulsion Polymerization of Methyl Methacrylate

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Chemical Research in Chinese Universities 2001年第3期17卷 325-330页

作者： dan yi YANG Yun-hua CHEN San-yu State Key Laboratory of Polymer Materials Engineering Department of Polymer Materials Science and EngineeringSichuan UniversityChengdu 610065P.R.China

The microemulsion polymerization of methyl methacrylate was studied. The effects of feeding modes on the structure and the properties of the obtained polymer microlatex were investigated by measuring the conversion, the transmittance and the refractive index of the latex, and by measuring the particle size, the molecular weight and the glass transition temperature (T_g) of the polymers. The results show that compared to the batch feeding mode, the semi-continuous feeding mode is more favorable to form a PMMA microlatex with a higher transmittance, a smaller particle size, a higher molecular weight and a higher T_g. And the obtained PMMA microlatex has a 30%—40% (mass fraction) polymer content, a 0. 03 emulsifier/water weight ratio, a 0. 05 emulsifier/monomer weight ratio and a 17 nm average particle diameter, which is very important for the industrialization of the microemulsion polymerization technique.

关键词： Microemulsion polymerization Methyl methacrylate Fedding mode Particle size

Numerical investigation of flow with floating vegetation island

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Journal of Hydrodynamics 2020年第1期32卷 31-43页

作者： yi-dan Ai Meng-yang Liu Wen-xin Huai State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China

Floating vegetation island(FVI)provides an effective way to remove excessive nutrition and pollutants in *** Reynolds stress model(RSM)is employed to investigate the hydrodynamic characteristics induced by varied canopy densities of FVI in an open *** longitudinal direction,four regions are subdivided according to the flow development process:upstream adjustment region(LUD),diverging flow region(LDF),shear layer growth region(LSD),and flilly developed *** increasing canopy density accelerates the flow adjustment in the diverging flow region and shear layer growth region,signaling a shorter distance to reach an equilibrium stage,while LUD keeps a *** vertical profiles of the normalized velocity are found to be self-similar downstream of the diverging flow *** the vertical direction,the streamwise velocity profiles in the mixing layer collapse for all densities and obey the hyperbolic tangent *** penetration depth into the canopy was fitted as a function of dimensionless canopy density given by δc/hc=0.404(CDahc)^-*** finding indicates a large space for rapid water renewal between the canopy region and the underlying water driven by the shear-scale *** the lateral direction,the intensification of secondary current and the increasing number of secondary current cells with increasing canopy density reveal that dense floating canopies contribute to strong momentum *** centers of vortices move as canopy density increases,while the vortices in canopy region do not merge with those in the gap region,as limited by the height and width of the canopy *** distribution of longitudinal velocity in the transects is significantly influenced by secondary current.

关键词： Reynolds stress model floating vegetation island flow adjustment mixing layer secondary current

Contagion dynamics on adaptive multiplex networks with awareness-dependent rewiring

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Chinese Physics B 2021年第5期30卷 708-723页

作者： Xiao-Long Peng yi-dan Zhang Complex Systems Research Center Shanxi UniversityTaiyuan 030006China Shanxi Key Laboratory of Mathematical Techniques and Big Data Analysis on Disease Control and Prevention Shanxi UniversityTaiyuan 030006China School of Mathematical Sciences Shanxi UniversityTaiyuan 030006China

Over the last few years,the interplay between contagion dynamics of social influences(e.g.,human awareness,risk perception,and information dissemination)and biological infections has been extensively investigated within the framework of multiplex *** vast majority of existing multiplex network spreading models typically resort to heterogeneous mean-field approximation and microscopic Markov chain *** approaches usually manifest richer dynamical properties on multiplex networks than those on simplex networks;however,they fall short of a subtle analysis of the variations in connections between nodes of the network and fail to account for the adaptive behavioral changes among individuals in response to epidemic *** transcend these limitations,in this paper we develop a highly integrated effective degree approach to modeling epidemic and awareness spreading processes on multiplex networks coupled with awareness-dependent adaptive *** approach keeps track of the number of nearest neighbors in each state of an individual;consequently,it allows for the integration of changes in local contacts into the multiplex network *** derive a formula for the threshold condition of contagion ***,we provide a lower bound for the threshold parameter to indicate the effect of adaptive *** threshold analysis is confirmed by extensive *** results show that awareness-dependent link rewiring plays an important role in enhancing the transmission threshold as well as lowering the epidemic ***,it is revealed that intensified awareness diffusion in conjunction with enhanced link rewiring makes a greater contribution to disease prevention and *** addition,the critical phenomenon is observed in the dependence of the epidemic threshold on the awareness diffusion rate,supporting the metacritical point previously reported in *** work may shed light on understanding of the interplay between e

关键词： epidemic spreading awareness diffusion adaptive rewiring multiplex networks

A scaling phenomenon for the cross section of fragment produced in projectile fragmentation reactions

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Science China(Physics,Mechanics & Astronomy) 2019年第9期62卷 60-69页

作者： yi-dan Song Hui-Ling Wei Chun-Wang Ma Institute of Particle and Nuclear Physics Henan Normal University

A scaling phenomenon has been found for the cross section of a fragment, which is defined as a "square" cross section(SCS).This phenomenon can unify the cross sections of fragments in projectile fragmentation(PF) reactions. An empirical formula is proposed to calculate SCSfor a fragment with parameters determined by an extensive investigation of measured reactions ranging from Fermi energies to relativistic energies. The scaling phenomenon of SCShas been verified using different techniques,showing that the scaling of SCSgenerally exists in PF reactions. The concept of SCS, which can be assumed as a standard value for a fragment, is shown to accurately predict the cross sections of isotopes in PF reactions with incident energies ranging from tens of A MeV to approximately 1000 A MeV.

关键词： scaling phenomenon cross section prediction intermediate mass fragments projectile fragmentation

Enhanced Wear Resistance of Ni/h-BN Composites with Graphene Addition Produced by Spark Plasma Sintering

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Acta Metallurgica Sinica(English Letters) 2019年第7期32卷 876-886页

作者： Jiao Xu dan-Qing yi Qiang Cui Bin Wang School of Material Science and Engineering Central South University Changsha 410083 China Light Alloy Research Institute Central South University Changsha 410083 China

Ni-based self-lubricating composites containing a fixed amount of hexagonal boron nitride (h-BN)(5 wt%) and different amounts of graphene (0-1.5 wt%) were prepared by ultrasonic dispersion, high-energy ball milling, and spark plasma sintering. The effects of the graphene content on the physical, mechanical, and wear properties of the Ni/h-BN composites were evaluated. These properties were first enhanced with increasing graphene content, reaching optimal behavior for a graphene content of 1 wt%, and then degraded with further graphene addition. Compared to the pure Ni/h-BN composite, the relative density, hardness, and bending strength of the composite with 1 wt% graphene increased by 2.7%, 7.4%, and 6.3%, respectively, while the friction coefficient decreased by 56% to 0.31, and a reduction in wear rate by a factor of 5-15 was observed. The mechanism for improving the wear properties of the composite with added graphene was due to the formation of a graphene lubricating film on the worn surface, which increased the load bearing capacity of the surface and enhanced lubrication during wear.

关键词： Graphene h-BN Wear Ni matrix composites

Effect of backward-facing step heights in vegetation-step model on reducing the velocity of a tsunami inundation and increasing the energy dissipation efficiency

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Journal of Hydrodynamics 2024年第5期36卷 803-816页

作者： Wen-xin Huai Xiao-hua Zhang dan Li Zhong-hua Yang yi-dan Ai State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China

A coastal forest combined with a backward-facing step is an efficient facility to reduce tsunami damage to residential areas behind sea *** study establishes a generalized model,and experimentally explores the water level changes upstream of the vegetation-step mitigation model as well as its energy dissipation effect under different initial Froude numbers,step heights,and vegetation *** results show that the relative backwater rise increases with the growth of vegetation density,patch length and initial Froude number,representing a slowing down of the tsunami *** for energy dissipation,it is mainly caused by the additional resistance of the vegetation and the hydraulic *** the vegetation condition not only affects the energy dissipation due to stem-scale turbulence within the patch,but also changes the hydraulic jump process of water falling from the step in cooperation with the step *** a result,the energy dissipation efficiency always increases with the growth of vegetation density,vegetation patch length and step *** the criterion that the energy dissipation efficiency and its growth rate can hardly change with vegetation parameters,this study innovatively defines the threshold slope and gives the principle of judging the most cost-effective vegetation conditions at different step *** results are expected to provide an important reference for the design of composite tsunami mitigation facilities.

关键词： Vegetation-step model step height backwater rise energy dissipation

Binding energies of near proton-drip line Z = 22-28 isotopes determined from measured isotopic cross section distributions

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Science China(Physics,Mechanics & Astronomy) 2019年第1期62卷 63-68页

作者： Chun-Wang Ma yi-dan Song Hui-Ling Wei College of Physics and Materials Science Henan Normal University Institute of Particle and Nuclear Physics Henan Normal University

A new method is proposed to determine the binding energy(B)of near proton-drip line isotopes from isotopic cross section *** determine B of Z=22-28 isotopes(with T_z=-2 and-5/2),the lack of cross sections for proton-rich isotopes in the 345A MeV^(78)Kr+~9Be is overcome by predicting the proton-rich isotopes from a newly discovered scaling phenomenon found in the proton-rich isotopes measured in the 140A MeV^(40,48)Ca(^(58,64)Ni)+~9Be *** cross sections for proton-rich isotopes are verified to exponentially depend on the average binding energy per nucleon,based on which B of the Z=22-28 isotopes with T_z=-2 and-5/2 are determined from cross *** determined B of the isotopes are justified from obeying the scaling phenomenon of the difference between the mass of mirror *** cross sections for the Z=22-28 isotopes with T_z=-1 and-3/2,which in potential can be experimentally studied in mass storage ring,are also predicted.

关键词： proton drip line binding energy mirror nuclei scaling phenomenon

Entanglement teleportation via a couple of quantum channels in Ising–Heisenberg spin chain model of a heterotrimetallic Fe–Mn–Cu coordination polymer

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Chinese Physics B 2019年第12期28卷 105-112页

作者： yi-dan Zheng Zhu Mao Bin Zhou Department of Physics Hubei UniversityWuhan 430062China

We investigate the teleportation of an entangled state via a couple of quantum channels, which are composed of a spin-1/2 Heisenberg dimer in two infinite Ising–Heisenberg chains. The heterotrimetallic coordination polymer CuⅡMnⅡ(L1)][FeⅢ(bpb)(CN)2]·ClO4·H2O(abbreviated as Fe–Mn–Cu) can be regarded as an actual material for this *** apply the transfer-matrix approach to obtain the density operator for the Heisenberg dimer and use the standard teleportation protocol to derive the analytical expression of the density matrix of the output state and the average fidelity of the entanglement teleportation. We study the effects of the temperature T, anisotropy coupling parameter △, Heisenberg coupling parameter J2 and external magnetic field h on the quantum channels. The results show that anisotropy coupling? and Heisenberg coupling J2 can favor the generation of the output concurrence and expand the scope of the successful average fidelity.

关键词： entanglement teleportation Ising–Heisenberg chain transfer-matrix approach concurrence

Enhanced photo-catalytic activity of the composite of TiO_2 and conjugated derivative of polyvinyl alcohol immobilized on cordierite under visible light irradiation

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Journal of Energy Chemistry 2016年第1期25卷 55-61页

作者： Jin Zhang Haigang Yang Long Jiang yi dan State Key Laboratory of Polymer Materials Engineering of China Polymer Research Institute of Sichuan University

A novel visible light active photo-catalyst named CHC/C-PVA/TiO2, the composite of titanium dioxide（TiO2）with conjugated derivative of polyvinyl alcohol（C-PVA） loaded on a cordierite honeycomb ceramic（CHC）substrate, was fabricated by combining the synthesis of TiO2 sol, preparation of C-PVA via thermally treating polyvinyl alcohol, and immobilization of TiO2 sol and C-PVA on CHC. By detecting the change of UV–vis absorption spectra of the model organic pollutant（methyl orange（MO）） in the presence of the composite under visible light irradiation, the photo-catalytic activity was evaluated and the results show that the CHC/C-PVA/TiO2 composite has an enhanced photo-catalytic activity when compared to the CHC/TiO2 composite. Besides, the CHC/C-PVA/TiO2 shows a good photo-catalytic stability after the fourth cycles. The structure analyses by scanning electron microscope（SEM） and energy dispersive X-ray spectroscopy（EDS） show the coexistence of C-PVA and TiO2 on the CHC and the cracks on the surface of CHC/C-PVA/TiO2. Result of ultraviolet-visible diffuse reflection spectroscopy（UV–vis DRS） reveals that the CHC/C-PVA/TiO2 can absorb both ultraviolet and visible light while result of X-ray photoelectron spectroscopy（XPS） indicates the existence of C, O and Ti elements in the CHC/C-PVA/TiO2. The typical structures as well as the optical characteristics of the CHC/C-PVA/TiO2 are responsible for the enhancement in the photo-catalytic activity.

关键词： Titanium dioxide Visible light Photo-catalysis Cordierite honeycomb Polyvinyl alcohol