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Studies on the Catalytic Properties of Magnesia Supported on γ-Alumina

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Chemical Research in Chinese Universities 2002年第2期18卷 196-199页

作者： JIAO Qing ze ZHAO yun li Xiao dan EVANS DG DUAN Xue Key Laboratory of Science and Technology of Controllable Chemical Reactions Ministry of EducationBeijing University of Chemical TechnologyBeijing 100029P.R.China

We have shown that MgO can be dispersed on γ Al 2O 3 with different loadings. The observed dispersion capacity of MgO on the surface of γ Al 2O 3 is higher than the theoretical monolayer dispersion value. The surface area and the maximum in the pore size distribution gradually decrease with the increase in MgO content at low loadings. The surface area and the maximum in the pore size distribution of MgO/ γ Al 2O 3 decrease more rapidly when the MgO content is large because the pores of γ Al 2O 3 become blocked. When small amounts of MgO are dispersed on the surface of γ Al 2O 3, the catalyst is very active and shows a good selectivity for the synthesis of glycol ethers.

关键词： Magnesia Alumina Dispersion Glycol ether

Effect of CeO_2 on heat transfer and crystallization behavior of rare earth alloy steel mold fluxes

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International Journal of Minerals,Metallurgy and Materials 2019年第5期26卷 565-572页

作者： ze-yun Cai Bo Song Long-fei li Zhen liu Xiao-kang Cui School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

To improve the heat transfer capability and the crystallization property of the traditional mold flux, CaF_2 was replaced with B_2O_3. Then, the influences of CeO_2 on the heat transfer and the crystallization of the CaF_2-bearing mold flux and the new mold flux with 10 wt% B_2O_3 were studied using a slag film heat flux simulator and X-ray diffraction(XRD). The results revealed that the addition of CeO2 reduced the heat transfer by increasing the solid slag thickness and the crystallization of two mold fluxes. However, CeO_2 had less effect on the B_2O_3-containing mold flux compared with the CaF_2-bearing mold flux. According to the analyses, the CeO_2 contents in the CaF_2-bearing mold flux and the B_2O_3-containing mold flux should not exceed 8 wt% and 12 wt%, respectively. Therefore, these experimental results are beneficial to improve and develop the mold flux for casting rare earth alloy steels.

关键词： cerium oxide boron trioxide mold fluxes heat transfer crystallization rare earth alloy steels

Use of a dietary exposure system for screening of insecticidal compounds for their toxicity to the planthopper Laodelphax striatellus

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Insect Science 2014年第5期21卷 667-675页

作者： zeng-Xia Wang Ke-Jian lin Jorg Romeis Yong-Lei liu ze-Wen liu yun-He li Yu-Fa peng State Key Laboratory for Biology of Plant Diseases and Insect Pests Institute of Plant Protection Chinese Academy of Agricultural Sciences Beijing Nanjing Agricultural University Nanjing China Agroscope Reckenholz-Tanikon Research Station ART ZurichSwitzerland

We developed a dietary exposure assay for screening insecticidal compounds for their toxicity and for assessing the side effects of insecticidal proteins produced by genetically engineered （GE） plants on the planthopper Laodelphax striatellus Fallen. The fitness bioassay confirmed that the diet fulfills the requirements to be used in the dietary exposure system. To validate the efficacy of the dietary exposure system, nymphs of L. striatellus were fed diets treated with different concentrations of an inorganic stomach poison, potassium arsenate （PA）, or a cysteine protease inhibitor, E-64. The results showed that with increasing concentrations of E-64, the larval development time was prolonged, the adult weight was reduced and the survival rate of L. striatellus was decreased. Similarly the survival rates of L. striatellus consistently decreased with increasing PA content in the diet. The data indicate that the dietary exposure assay is able to detect the effects of insecticidal compounds on L. striatellus. Subsequently, this assay was successfully used for assessing the potential toxicity of Cry2Aa. The results showed that L. striatellus larvae were not negatively affected when fed the artificial diet containing purified Cry2Aa at 300 μg/g diet. In the assay, the stability and bioactivity of crystal （Cry） proteins in the food sources were confirmed by enzyme-linked immunosorbent assay and sensitive-insect bioassays. These results show that L. striatellus is not sensitive to Cry2Aa. We conclude that the dietary exposure system is valid and useful for assessing the toxicity of insecticidal compounds produced by GE plants on planthoppers.

关键词： Cry2Aa E-64 genetically engineered rice potassium arsenate risk assessment

Parallel Optimization of the Crystal-KMC on Tianhe-2

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Tsinghua Science and Technology 2021年第3期26卷 309-321页

作者： Jianjiang li Baixue Ji yun Yang peng Wei Jie Wu Department of Computer Science and Technology University of Science and Technology BeijingBeijing 100083China Industrial and Commercial Bank of China Shandong Branch Jinan 250001China Department of Computer and Information Sciences Temple UniversityPhiladelphiaPA 19122USA

The Kinetic Monte Carlo(KMC)is one of the commonly used methods for simulating radiation damage of *** team develops a parallel KMC software named Crystal-KMC,which supports the Embedded Atom Method(EAM)potential energy and utilizes the Message Passing Interface(MPI)technology to simulate the vacancy transition of the Copper(Cu)element under neutron *** make better use of the computing power of modern supercomputers,we develop the parallel efficiency optimization model for the Crystal-KMC on Tianhe-2,to achieve a larger simulation of the damage process of materials under irradiation ***,we analyze the performance bottleneck of the Crystal-KMC software and use the MIC offload statement to implement the operation of key modules of the software on the MIC *** use Open MP to develop parallel optimization for the Crystal-KMC,combined with existing MPI inter-process communication optimization,finally achieving hybrid parallel *** experimental results show that in the single-node CPU and MIC collaborative parallel mode,the speedup of the calculation hotspot reaches 30.1,and the speedup of the overall software reaches 7.43.

关键词： Kinetic Monte Carlo(KMC) Tianhe-2 paral el optimization OpenMP

Dependence of Performance of Organic light-emitting Devices on Sheet Resistance of Indium-tin-oxide Anodes

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Chemical Research in Chinese Universities 2006年第4期22卷 427-431页

作者： ZHOU liang ZHANG Hong-jie YU Jiang-bo MENG Qing-guo peng Chun-yun liU Feng-yi DENG Rui-ping peng ze-ping li Zhe-feng Key Laboratory of Rare Earth Chemistry and Physics Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 P. R. China

The dependence of the performance of organic light-emitting devices（OLEDs） on the sheet resistance of indiumtin-oxide（ITO） anodes was investigated by measuring the steady state current density brightness voltage characteristics and the electroluminescent spectra. The device with a higher sheet resistance anode shows a lower current density, a lower brightness level, and a higher operation voltage. The electroluminescence（EL） efficiencies of the devices with the same structure but different ITO anodes show more complicated differences. Furthermore, the shift of the light-emitting zone toward the anode was found when an anode with a higher sheet resistance was used. These performance differences are discussed and attributed to the reduction of hole injection and the increase in voltage drop over ITO anode with the increase in sheet resistance.

关键词： Organic light-emitting device(OLED) Indium-tin-oxide(ITO) Sheet resistance Balance of holes and electrons

Evaluation of the stability of vegetated slopes according to layout and temporal changes

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Journal of Mountain Science 2021年第1期18卷 275-290页

作者： li yun-peng HU Chao JIAN li ZHAO Ran li Chen China Academy of Transportation Sciences Beijing 100029China. Qilu Transportation Development Group Jinan 250101China

Vegetation in slopes can effectively improve slope ***,it is difficult to estimate the effects of vegetation on slope stability because of variations in plant species and environmental ***,influences of plant growth on slope stability change with time,resulting in changes in the safety *** study was conducted to evaluate the stability of vegetated slopes with time and investigate the effects of different layouts of plant species on slope ***,we used a plant growth model and slope stability analysis to build an evaluation *** accomplish this,one species of tree,shrub and grass was chosen to set six layout patterns.A slope with no vegetation served as a *** safety factors of the seven slopes were then calculated using the developed evaluation model and differences in the safety factors of slopes were compared and *** slope vegetated with Platycladus orientalis reached the most stable state at the age of 60 *** slope(Vitex negundo)had the maximum safety factor after 20 ***,the safety factor of vegetated slopes increased from 12.1%to 49.6% compared to the slope with no *** wind force was considered,the safety factor value of the slope changed from 3.5%to 43.5%.Vegetation mixtures of trees and grasses resulted in the best slope *** grasses on slopes can improve slope stability of trees to a greater degree than that of slopes with shrubs in the early stage of growth.

关键词： Plant growth model Vegetated slope Slope stability Safety factor

Microstructure evolution and nucleation mechanism of Inconel 601H alloy welds by vibration-assisted GTAW

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International Journal of Minerals,Metallurgy and Materials 2018年第7期25卷 788-799页

作者： ze-long Wang Zhen-tai Zheng li-bing Zhao yun-feng Lei Kun Yang School of Materials Science and Engineering Hebei University of TechnologyTianjin 300130China Beiyang Chemical Equipment of Tianjin University Co. Ltd.Tianjin 300110China

Nickel-based alloys exhibit excellent high-temperature stxengtfi and oxidation resistance; however, because of coarse grains and severe segregation in daeir welding joints, these alloys exhibit increased susceptibility to hot cracking. In this paper, to improve the hot-cracking resistance and mechaxtical properties ofinckel-based alloy welded joints, sodium daiosulfate was used to simulate crystallization, enabling the nucleation mechanism under mechaxtical vibration to be investigated. On the basis of the results, the grain refinement mechan- ism during the gas tungsten arc welding （GTAW） of Inconel 601H alloy under wxious vibration modes and parameters was investigated. Compared witfi the GTAW process, the low-frequency mechanical vibration processes resulted in substantial grain refinement effects in the welds; thus, a higher haxdness distxibution was also achieved under the vibration conditions. In addition, the 7＇ phase exhibited a dispersed distribution and segregation was improved in the welded joints witfi vibration assistance. The results demonstxated that the generation of free crystals caused by vibration in the nucleation stage was the main mechaxtism of grain refinement. Also, free equiaxed grains and a dispersed 7＇ phase were found to improve the grain-boundary strength and reduce the segregation, contributing to preventing the initiation of welding hot cracking in nickel-based alloys.

关键词： mechanical vibration nickel-based alloy grain refinement microst3-ucture hot cracking

Effects of pressure on structure and dynamics of metallic glass-forming liquid with miscibility gap

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Journal of Iron and Steel Research International 2018年第6期25卷 666-673页

作者： yun Cheng peng-fei Wang Chuan-xiao peng li jing Jia Yu-yang Wang li Wang School of Mechanical Electrical and InformationEngineering Shandong University (Weihai)Weihai 264209 Shandong China

The metallic liquid with miscibility gap has been widely explored recently because of the increasing plastic deformation ability of phase-separated metallic glass. However, the poor glass-forming ability limits its application as the structural materials due to the positive mixing enthalpy of the two elements. Since high pressure is in favor of the formation of the glass, the effect of pressure on the structural and dynamical heterogeneity of phase-separated CusoAgso liquid is inves- tigated by molecular dynamics simulation in the pressure range of 0-16 GPa. The results clearly show that the pressure promotes the formation of metallic glass by increasing the number of fivefold symmetry cluster W and dynamical relaxation time; meanwhile, the liquid-liquid phase separation is also enhanced, and the homogenous atom pAlrs show stronger interaction than heterogeneous atom pAlrs with increasing pressure. The dynamical heterogeneity is related to the formation of fivefold symmetry clusters. The lower growing rate of W at higher pressure with decreasing temperature corresponds to the slow increase in dynamical heterogeneity. The pressured glass with miscibility gap may act as a candidate glass with improved plastic formation ability. The results explore the structural and dynamical heterogeneity of phase-separated liquid at atomic level.

关键词： Glass-forming liquid Miscibility gap High pressure Structural heterogeneity Dynamical heterogeneity Molecular dynamics simulation

Probing the sign-changeable interaction between dark energy and dark matter with current observations

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Science China(Physics,Mechanics & Astronomy) 2018年第3期61卷 1-9页

作者： Juan-Juan Guo Jing-Fei Zhang yun-He li Dong-ze He Xin Zhang Department of Physics College of Sciences Northeastern University Center for High Energy Physics Peking University

We consider the models of vacuum energy interacting with cold dark matter in this study, in which the coupling can change sigh during the cosmological evolution. We parameterize the running coupling b by the form b（a） = boa ＋ be（1 - a）, where at the earlytime the coupling is given by a constant be and today the coupling is described by another constant bo. We explore six specific models with （i） Q = b（a）Hoρo, （ii） Q = b（a）Hoρde, （iii） Q = b（a）Hoρc, （iv） Q = b（a）Hρo, （v） Q = b（a）Hρde, and （vi） Q = b（a）Hρc. The current observational data sets we use to constrain the models include the JLA compilation of type Ia supernova data, the Planck 2015 distance priors data of cosmic microwave background observation, the baryon acoustic oscillations measurements and the Hubble constant direct measurement. We find that, for all the models, we have b0 〈 0 and be 〉 0 at around the lolevel, and b0 and be are in extremely strong anti-correlation. Our results show that the coupling changes sign during the evolution at about the lolevel, i.e., the energy transfer is from dark matter to dark energy when dark matter dominates the universe and the energy transfer is from dark energy to dark matter when dark energy dominates the universe.

关键词： interacting dark energy sign-changeable interaction running coupling observational constraints