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Binuclear Aluminum Complexes Supported by Linked Bis(β-diketiminate) Ligands for Ring-Opening Polymerization of Cyclic Esters

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Chinese Journal of Polymer Science 2018年第2期36卷 190-201页

作者： Shaogang Gong peng du Haiyan Ma Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry School of Chemistry and Molecular EngineeringEast China University of Science and Technology

Binuclear aluminum alkyl complexes 2a–4g supported by linked bis（β-diketiminate） ligands were synthesized via the reaction of AlEt3 or AlMe3 and the corresponding proligand in a 2：1 molar ratio with moderate yields. The isolated complexes were well-characterized by ^1H-NMR, ^13C-NMR and elemental analysis. The binuclear nature of aluminum complex 2b was further confirmed by an X-ray diffraction study. All complexes 2a–4g could efficiently initiate the ring-opening polymerization（ROP） of ε-caprolactone in toluene. The substituents at the aromatic rings and the linker unit in the auxiliary ligands exerted significant influence on the catalytic behavior of the investigated aluminum complexes. Complex 4g（R^1 = R^2 = Cl） containing propylenyl bridging unit exhibited the highest catalytic activity among these complexes, which might be attributed to the increased electrophilicity of the metal center as well as more opened coordination sphere. The molecular weights of obtained poly（ε-caprolactone）s deviating considerably from the theoretical values indicated that the ROP of ε-caprolactone by complexes 2a–4g was not well-controlled, which was also judged from the broad molecular weight distributions（MWD = 1.47-2.47） of produced poly（ε-caprolactone）s. These complexes proved to be inactive toward the polymerization of rac-lactide alone. In the presence of alcohol the polymerization occurred, which was actually initiated by the decomposition species of the aluminum complex upon the treatment with isopropanol.

关键词： Bis(β-diketiminate) ligand Aluminum complex Binuclear Polymerization Cyclic ester

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Calculation of microscopic nuclear level densities based on covariant density functional theory

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Nuclear Science and Techniques 2023年第9期34卷 118-127页

作者： Kun-peng Geng peng-Xiang du Jian Li Dong-Liang Fang College of Physics Jilin UniversityChangchun 130012China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China

In this study,a microscopic method for calculating the nuclear level density(NLD)based on the covariant density functional theory(CDFT)is *** particle-hole state density is calculated by a combinatorial method using single-particle level schemes obtained from the CDFT,and the level densities are then obtained by considering collective effects such as vibration and *** results are compared with those of other NLD models,including phenomenological,microstatisti-cal and nonrelativistic Hartree–Fock–Bogoliubov combinatorial *** comparison suggests that the general trends among these models are essentially the same,except for some deviations among the different NLD *** addition,the NLDs obtained using the CDFT combinatorial method with normalization are compared with experimental data,including the observed cumulative number of levels at low excitation energies and the measured *** CDFT combinatorial method yields results that are in reasonable agreement with the existing experimental data.

关键词： Nuclear level density Covariant density functional theory Combinatorial method

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Nucleation mechanisms of dynamic recrystallization in Inconel 625 superalloy deformed with different strain rates

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Rare Metals 2012年第3期31卷 215-220页

作者： Guo, Qingmiao Li, Defu peng, Haijian Guo, Shengli Hu, Jie du, peng Nonferrous Metals Processing Division General Research Institute for Nonferrous Metals Beijing 100088 China

The effects of strain rates on the hot working characteristics and nucleation mechanisms of dynamic recrystallization (DRX) were studied by optical microscopy and electron backscatter diffraction (EBSD) technique. Hot compression tests were conducted using a Gleeble-1500 simulator at a true strain of 0.7 in the temperature range of 1000 to 1150 °C and strain rate range of 0.01 to 10.00 s?1. It is found that the size and volume fraction of the DRX grains in hot-deformed Inconel 625 superalloy firstly decrease and then increase with increasing strain rate. Meanwhile, the nucleation mechanism of DRX is closely related to the deformation strain rate due to the deformation thermal effect. The discontinuous DRX (DDRX) with bulging of original grain boundaries is the primary nucleation mechanism of DRX, while the continuous DRX (CDRX) with progressive subgrain rotation acts as a secondary nucleation mechanism. The twinning formation can activate the nucleation of DRX. The effects of bulging of original grain boundaries and twinning formation are firstly gradually weakened and then strengthened with the increasing strain rate due to the deformation thermal effect. On the contrary, the effect of subgrain rotation is firstly gradually strengthened and then weakened with the increasing strain rate.

关键词： nucleation mechanisms dynamic recrystallization Inconel 625 superalloy deformation strain rate

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Evolution and Characterization of Damage of Concrete under Freeze-thaw Cycles

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Journal of Wuhan University of Technology(Materials Science) 2013年第4期28卷 710-714页

作者：王玲 CAO Yin WANG Zhendi du peng State Key Laboratory of Green Building Materials China Building Materials Academy

To study the internal damage of concrete under freeze-thaw cycles, concrete strains were measured using embedded strain gauges. Residual strain and coefficients of freezing expansion （CFE） derived from strain-temperature curves were used to quantify the damage degree. The experimental results show that irreversible residual strain increases with the number of freeze-thaw cycles. After 50 cycles, residual strains of C20 and C35 concretes are 320με and 100με in water, and 120με and 60 με in saline solution, respectively. In lower temperature range （- 10 ℃ to - 25 ℃） CFE of C20 and C35 concretes decrease by 9.82 × 10-6/K and 8.44×10-6/K in water, and 9.38×10-6/K and 5.47×10-6/K in saline solution, respectively. Both residual strains and CFEs indicate that during the first 50 freeze-thaw cycles, the internal damage of concrete in saline solution is less than that of concrete in water. Thus residual strain and CFE can be used to measure the frost damage of concrete.

关键词： freeze-thaw cycles saline solution strain residual strain coefficients of freezing expansion

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New cross-matching algorithm in large-scale catalogs with ThreadPool technique

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Science China(Physics,Mechanics & Astronomy) 2014年第3期57卷 577-583页

作者： du peng REN JuanJuan PAN JingChang LUO ALi School of Mechanical Electrical & Information EngineeringShandong University Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of Sciences

We introduce an algorithm to solve the block-edge problem taking advantage of the two different sky splitting functions： HTM and HEALPix. We make the cross-match with the two functions, and then we obtain the union set of the two different sets. We use the ThreadPool technique to speed up the cross-match. In this way improved accuracy can be obtained on the cross-match. Our experiments show that this algorithm has a remarkable performance superiority compared with the previous ones and can be applied to the cross-match between large-scale catalogs. We give some ideas about solving the many-for-one situation occurred in the cross-match.

关键词： cross-match astronomical catalogs methods: HTM and HEALPix ThreadPool

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Climate change, environmental factors, and COVID-19: Current evidence and urgent actions

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The Innovation 2021年第3期2卷 11-12页

作者： Runmei Ma peng du Tiantian Li China CDC Key Laboratory of Environment and Population Health National Institute of Environmental HealthChinese Center for Disease Control and PreventionBeijing 100021China

The novel coronavirus disease(COVID-19)has triggered an international health crisis that began in late *** number of COVID-19 cases globally remains at the highest levels,and variants of the SARS-CoV-2 being reported around the world have caused special *** COVID-19 pandemic requires a regular global *** is the case with other infectious respiratory diseases,COVID-19 may be affected by climatic,meteorological,and environmental factors,including temperature,humidity,and air *** interactive effects of these factors on population health are ***,policy responses to COVID-19 have substantially affected socio-economic systems and people’s lifestyles,which in turn had an impact on climate by reducing emissions and population adaptations under the background of climate change,and even further affected the human *** actions are needed to respond to both climate change and COVID-19,and in turn the climate impacts of the COVID-19 pandemic(Figure 1).

关键词： climate meteorological humidity

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Pricing Competition between Innovator and Imitator Facing Strategic Customers

Pricing Competition between Innovator and Imitator Facing St...

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第25届中国控制与决策会议

作者： du peng Chen Qiushuang Zhao Han Department of Automation College of Information Technical Science Nankai University Basic Department of Military Economics University

ISBN: (纸本)9781467355339

When an innovative product is introduced into the market, the innovator realizes that she will always face the competition of entrant imitator（s） after a period of monopoly time. Strategic customers may also anticipate that and can rationally make their purchase plan, which further complicates the situation of competition. In this paper, we develop a dynamic game model to formulate the problem and obtain the pricing equilibrium. In numerical studies, the relative position of monopoly price, the markdown size of the innovator and the relative price difference between the two firms are investigated to analyze the impacts of various factors on the pricing policies.

关键词： Pricing Competition Innovation Imitation Strategic Customers

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Low Surface Brightness Galaxies from BASS+MzLS with Machine Learning

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Research in Astronomy and Astrophysics 2024年第5期24卷 185-197页

作者： peng-Liang du Wei du Bing-Qing Zhang Zhen-Ping Yi Min He Hong Wu Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China School of Mechanical Electrical and Information EngineeringShandong UniversityWeihai 264209China

From ∼5000 deg^(2) of the combination of the Beijing–Arizona Sky Survey and Mayall z-band Legacy Survey which is also the northern sky region of the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys, we selected a sample of 31,825 candidates of low surface brightness galaxies (LSBGs) with the mean effective surface brightness 24.2 0.60) LSBGs. The blue LSBGs appear spiral, disk or irregular while the red LSBGs are spheroidal or elliptical and spatially clustered. This trend shows that the color has a strong correlation with galaxy morphology for LSBGs. In the spatial distribution, the blue LSBGs are more uniformly distributed while the red ones are highly clustered, indicating that red LSBGs preferentially populate a denser environment than the blue LSBGs. Besides, both populations have a consistent distribution of ellipticity (median ∈∼ 0.3), half-light radius (median r_(eff) ∼ 4″) and Sérsic index (median n=1), implying the dominance of the full sample by the round and disk galaxies. This sample has definitely extended the studies of LSBGs to a regime of lower surface brightness, fainter magnitude and broader other properties than the previously Sloan Digital Sky Survey-based samples.

关键词： catalogs-galaxies fundamental parameters-galaxies statistics-techniques photometric

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DISTRIBUTED PROPORTIONAL FAIR FREQUENCY ALLOCATION ACROSS MULTIPLE BASE STATIONS

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Journal of Electronics(China) 2013年第4期30卷 335-340页

作者： du peng Meng Qingmin College of Automation Nanjing University of Posts and Telecommunications College of Telecommunications and Information Engineering Nanjing University of Posts and Telecommunications Interdisciplinary Centre for Security Reliability and Trust (SnT) the University of Luxembourg

The problem of distributed proportional fair inter-cell frequency allocation for flat-structured cellular systems is studied in this paper. We firstly propose a framework of the frequency allocation in which the whole frequency allocation process is decomposed into many consecutive stages, then identify that for each stage the key is to find the Maximum Weight Independent Set (MWIS) in a given weighted conflict graph in the distributed manner. A new distributed algorithm for MWIS is described in which each node iteratively exchanges messages with neighbors. With this distributed MWIS algorithm, a new distributed proportional fair frequency allocation scheme is presented. The performance of the proposed algorithm is tested in computer experiments simulating the Long Term Evolution (LTE) cellular systems. Simulation results show the performance of the proposed distributed proportional fair frequency allocation scheme is comparable with the centralized ones.

关键词： Distributed algorithm Proportional fair Frequency allocation Cellular networks

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Fabrication of porous TiZrNbTa high-entropy alloys/Ti composite with high strength and low Young’s modulus using a novel MgO space holder

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Journal of Materials Science & Technology 2023年第36期167卷 59-73页

作者： Tao Xiang Jie Chen Weizong Bao Shuyan Zhong peng du Guoqiang Xie School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Stress shielding is caused by the mismatch of stiffness between bone and implant materials,which may give rise to bone resorption and loosening,thereby causing implantation *** is a huge gap between Young’s modulus of human bone and low Young’s modulusβTi alloys.A porous structure design can achieve the target of low Young’s modulus,and thus achieve the matching between human bone and implant ***,a suitable space holder(SH)that can be applied at high temperatures and sintering pressure has not been *** this study,the TiZrNbTa/Ti titanium matrix composite(TMC)with high strength and large ductility was used as scaffold materials and combined the SH technique with the spark plasma sintering(SPS)technique to obtain a porous structure.A novel space holder,i.e.,MgO particles was adopted,which can withstand high-temperature sintering accompanied by a sintering *** porous TiZrNbTa/Ti with 40 vol.%MgO added exhibits a maximum strength of 345.9±10.4 MPa and Young’s modulus of 24.72±0.20 GPa,*** possesses higher strength compared with human bone and matches Young’s modulus of human bone,which exhibits great potential for clinical application.

关键词： TiZrNbTa/Ti titanium matrix composite MgO space holder Low Young’s modulus High strength

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