检索结果-南通市图书馆

A convenient method to prepare random LA/CL copolymers from poly(L-lactide) and ε-caprolactone

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2018年第6期61卷 708-714页

作者： Hao Ouyang Kun nie Dan Yuan yong Zhang Dongmei Cui Yingming Yao Key Laboratory of Organic Synthesis of Jiangsu Province Suzhou Key Laboratory of Macromolecular Design and Precision Synthesisand State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials College of Chemistry Chemical Engineering and Materials Science Dushu Lake Campus Soochow University School of Chemistry and Chemical Engineering Taishan University State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences

Sequential addition of L-lactide(LA) followed by ε-caprolactone(CL), and simultaneous addition of both monomers, afforded random LA/CL copolymers in the presence of lanthanide aryloxides under mild conditions. Transesterification was proved to play a predominant role in random copolymer formation. Moreover, treatment of poly(L-lactide) with ε-CL led to random copolymer formation, which provides a new strategy not only to prepare random LA/CL copolymers, but also to directly modify PLLA.

关键词： random copolymers lanthanide complex transesterification lactide ε-caprolactone

Microstructure, Tensile Properties and Work Hardening Behavior of an Extruded Mg–Zn–Ca–Mn Magnesium Alloy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2020年第7期33卷 922-936页

作者： Kai-Bo nie zhi-Hao Zhu Paul Munroe Kun-Kun Deng Jun-Gang Han College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China School of Materials Science and Engineering UNSW AustraliaKensingtonNSW 2052Australia

A new Mg-2.2 wt% Zn alloy containing 1.8 wt% Ca and 0.5 wt% Mn has been developed and subjected to extrusion under different extrusion *** finest(~0.48 μm) recrystallized grain structures,containing both nano-sized MgZn2 precipitates and α-Mn nanoparticles,were obtained in the alloy extruded at 270℃/0.01 mm *** this alloy,the deformed coarse-grain region possessed a much stronger texture intensity(~32.49 mud) relative to the recrystallized fine-grain region(~13.99 mud).A positive work hardening rate in the third stage of work hardening curve was also evident in the alloy extruded at 270℃,which was related to the sharp basal texture and which provided insufficient active slip *** high work hardening rate in the fourth stage contributed to the high ductility extruded at 270℃/1 mm *** alloy exhibited a weak texture,and the examination of fracture surface revealed highly dimpled *** optimum tensile strength was achieved in the alloy extruded at 270℃/0.01 mm s-1,and the yield strength,ultimate tensile strength and elongation to failure were^364.1 MPa,~394.5 MPa and^7.2%,*** grain strengthening from the recrystallized fine-grain region played the greatest role in the strength increment of this alloy compared with Orowan strengthening and dislocation strengthening in the deformed coarse-grain regions.

关键词： alloy grain strengthening

Molecular Dynamics Simulations of Stretch-Induced Crystal Changes in Crystallized Polyethylene/Carbon Nanotubes Nanocomposites

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2023年第9期41卷 1425-1438,I0007页

作者： Yu-Hang Zhou Jun Yang zhi-Ping Zhou Tong-Fan Hao Yi-Jing nie Research School of Polymeric Materials School of Materials Science and EngineeringJiangsu UniversityZhenjiang212013China

Understanding deformation mechanisms in semi-crystalline polymers during stretching is useful for guiding the processing of highperformance polymer products. In the current work, molecular dynamics simulations were performed to investigate the crystal changes in crystallized polyethylene/carbon nanotube nanocomposites during uniaxial stretching. Both crystal fragmentation and melting occur at low strains. Crystals with small sizes are easier to melt, while those with large sizes would break into smaller crystals. In addition, crystals in interfacial regions are more likely to melt or break due to the orientation motion of carbon nanotubes. It was also found that the recrystallization process is closely related to the stretch-induced orientation of chain segments. After orientation of chain segments along stretching direction is saturated,the recrystallization of highly oriented segments dominates. The current simulation findings are effective complements to the theories of the mechanism of plastic deformation in semicrystalline polymers.

关键词： Molecular dynamics simulation Carbon nanotubes Stretching Melting and recrystallization

Martensitic transformation,shape memory effect and superelasticity of Ti-xZr-(30-x)Nb-4Ta alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2019年第10期38卷 965-970页

作者： Wen-Tao Qu Hao Gong Jun Wang yong-Sheng nie Yan Li School of Mechanical Engineering Xi'an Shiyou UniversityXi’an 710065China School of Materials Science and Engineering Beihang UniversityBeijing 100191China Beijing Advanced Innovation Centre for Biomedical Engineering Beihang UniversityBeijing 100191China Lanzhou Seemine SMA Co.Ltd Lanzhou 730010China

Martensitic transformations,mechanical properties,shape memory effect and superelasticity of Ti-xZr-(30-x)Nb-4Ta(x=15,16,17 and 18;at%) alloys were investigated.X-ray diffraction(XRD),optical microscopy(OM) and transmission electron microscopy(TEM) results indicated that the Ti-16Zr-14Nb-4Ta,Ti-17Zr-13Nb-4Ta and Ti-18Zr-12Nb4Ta alloys were mainly composed of α″-martensite,while the Ti-15Zr-15Nb-4Ta alloy was characterized by predominant p *** reverse martensitic transformation temperatures increased when Nb was replaced by Zr,indicating stronger p-stabilizing effect for the *** Ti-15Zr-15Nb-4Ta alloy displayed superelasticity during tensile deformation with a recovery strain of 3.51%.For the other three alloys with higher Zr content,the martensitic reorientation occurred during tensile deformation,resulting in shape memory recovery upon subsequent *** maximum shape memory effect was 3.46% in the Ti-18Zr-12Nb-4Ta alloy.

关键词： Ti-Zr alloys Martensitic transformation Shape memory effect Superelasticity

Solute atom segregation to I1 stacking fault and its bounding partial dislocations in a Mg–Bi alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第8期12卷 3135-3141页

作者： Cong He yong Zhang zhiqiao Li Houwen Chen Jian-Feng nie International Joint Laboratory for Light Alloys(Ministry of Education) College of Materials Science and EngineeringChongqing UniversityChongqing 400044PR China Research Center for Magnetic and Spintronic Materials National Institute for Materials ScienceTsukuba 305-0047Japan Department of Materials Science and Engineering Monash UniversityVictoria 3800Australia State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082PR China

Stacking faults(SFs)and the interaction between solute atoms and SFs in a Mg–Bi alloy are investigated using aberration-corrected scanning transmission electron *** is found that abundant I_(1)SFs are generated after cold rolling and are mainly distributed inside{1012}*** aging treatment,the formation of single-layer and three-layer Bi atom segregation in the vicinity of I_(1)fault are clearly *** segregation also occurs at the 1/6bounding Frank partial dislocation *** segregation behaviors in I_(1)fault and Frank dislocations are discussed and rationalized using first-principles calculations.

关键词： Mg alloys Suzuki segregation Stacking fault Frank partial dislocation

Synthesis and fluorescent properties in complexes of Eu( Ⅲ), Tb( Ⅲ), and Sm( Ⅲ) with β-diketone and 2,2′-bipyridine

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2012年第5期31卷 -页

作者： LIU Xingwang JIANG Jiadong GUO Yuwei yong Shengli YANG Kun nie Lu School of Chemistry Baotou Teachers' College Baotou 014030 China School of Chemical Engineering Inner Mongolia University of Technology Hohhot 010051 China

Three new rare earth ternary complexes, RE(PB)_3bpy (RE=Sm^(3+) , Eu^(3+) , and Tb^(3+) ), were synthesized by the reaction of 1-(p-phenylethynyl- phenyl)-1,3-butanedione (HPB) and 2,2′-bipyridine (bpy) with rare earth chloride RECl_3 , respectively, in alcohol solution. The compositions were characterized by means of infrared (IR) spectra, chemical analysis, elemental analysis, and thermodynamic analysis. Luminescent properties of the three complexes were studied. At room temperature, under UV light excitation, the Sm^(3+) , Eu^(3+) , and Tb^(3+) complexes exhibit characteristic emission of the central ions. The fluorescence spectra show that the fluorescence emission intensity of Eu^(3+) complex is the strongest. The narrow strongest emission band of Eu^(3+) complex is considered to be a valuable material with bright red fluorescence.

关键词： β-diketone 2,2′-bipyridine lanthanide complex luminescent property

Active constraints selection based semi-supervised dimensionality in ensemble subspaces

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2015年第5期26卷 1088-1099页

作者： Jie Zeng Wei nie yong Zhang College of Information Engineering Shenzhen University Modern Communication and Information Processing Key Laboratory Shenzhen University ATR Key Laboratory of National Defense Technology Shenzhen University

Semi-supervised dimensionality reduction(SSDR) has attracted an increasing amount of attention in this big-data *** algorithms have been developed with a small number of pairwise constraints to achieve performances comparable to those of fully supervised methods. However, one challenging problem with semi-supervised approaches is the appropriate choice of the constraint set, including the cardinality and the composition of the constraint set, which to a large extent, affects the performance of the resulting algorithm. In this work, we address the problem by incorporating ensemble subspace and active learning into dimensionality reduction and propose a new algorithm, termed as global and local scatter based SSDR with active pairwise constraints selection in ensemble subspaces(SSGL-ESA). Unlike traditional methods that select the supervised information in one subspace,we pick up pairwise constraints in ensemble subspace, where a novel active learning algorithm is designed with both exploration and filtering to generate informative pairwise constraints. The automatic constraint selection approach proposed in this paper can be generalized to be used with all constraint-based semi-supervised learning algorithms. Comparative experiments are conducted on two face database and the results validate the effectiveness of the proposed method.

关键词： semi-supervised dimensionality reduction(SSDR) ensemble subspace active learning machine learning

Cyclin-dependent kinase 5 is required for suppressing D1-dependent signaling mediated through muscarinic 4 in isolated medium spiny neurons

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

中国药理学与毒理学杂志 2018年第9期32卷 689-690页

作者： ZHOU Hu YANG Pei nie zhi-yong SHI Jing-shan WANG Li-yun LI Jin Beijing Institute of Pharmacology and Toxicology Beijing 100850 China Zunyi Medical University Zunyi 563000 China

OBJECTIVE Previous studies have demonstrated acetylcholine muscarinic 4(M4) receptor regulates DARPP-32 phosphorylation at Thr75 in isolated medium spiny neurons(MSNs),indicating antagonistic mechanism with D1 dependent signal cascade,but the exact molecular mechanisms remain *** this study,we investigated the roles of M4 receptor in modulation D1 dependent signal to integrate striatal DA inputs in isolated ***(1)Lentivirus technology was employed to genetically knock down the M4 receptor of MSNs;(2) Apomorphine(APO),acts as a dopamine receptor agonist,while SCH23390,acts as a selective antagonist for D1,were used to study the pharmacologically profiles with D1 receptor stimulation or blockade,*** the no subtype-selective muscarinic agonist oxotremorine M(OX) were used to show that mAchRs activation,in order to dissect the particular function of M4,a selective M4 antagonist,MT3 was used;(3) Intracellular cAMP production of MSNs was measured by using time resolved fluorescence resonance energy transfer detection method;(4) Laser confocal was used to explore the expression of M4 and D1 in MSNs;(5) Immunofluorescence cytochemistry and Western blotting were used to confirm the alteration of signaling molecular including P-CREB,DARPP-32 P-Thr34,DARPP-32 P-Thr75,cyclin-dependent kinase 5(CDK5) as wel as p25/35,which are involved in DA-dependent signaling *** Firstly,TR-FRET assay revealed APO(10-2 mol·L^(-1))significantly increased the level of intracellular cAMP(vs control,n=3,P<0.01),also Western blotting results showed that APO(10-6 mol · L^(-1))increased DARPP-32 Thr34 phosphorylation(vs control,n=3,P<0.01),and these effect were reversed by D1 receptor antagonist SCH23390(vs APO,n=3,P<0.01).Interestingly,we confirmed that OX(10-6 mol · L^(-1)) down-regulated APO-induced DARPP-32 Thr34 phosphorylation(vs APO,n=3,P<0.01),due to its effects on DARPP-32 phosphorylation at *** results presented the antagonistic mechanis

关键词： acetylcholine M4 receptor dopamine D1 receptor DARPP32 phosphorylation cyclin-dependent kinase 5

Integrated approach for optimal island partition and power dispatch

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2018年第3期6卷 449-462页

作者： Junpeng ZHU Wei GU Ping JIANG zhi WU Xiaodong YUAN Yinghui nie School of Electrical Engineering Southeast University Jiangsu Electric Power Company Research Institute

Operating in island mode when failure occurs in sure to maintain an uninterrupted power supply to significant loads. A two-stage approach that integrates optimal island partition and power dispatch is proposed in this paper, considering photovoltaics(PVs), batteries(BEs) and electric vehicles(EVs) as the power sources. In the first stage, energy indices are defined to describe the energy demand and the maximum energy that these distributed energy resources(DERs) can provide, and islands are partitioned based on an energy constraint. Considering the variability the loads and PVs, the energy constraint is a necessary but not sufficient condition for island operation,so in the second stage, a power dispatch model is proposed the active distribution network(ADN) is an effective mea-as a test for the island partition result. Sequential power flow is also simulated to guarantee a feasible and optimized island status. The situations when the tests are not passed are analyzed and classified, and corresponding modifications for the first stage model are provided. Multiple levels of constraints based on the energy index are established for the island partition model. The proposed approach has been validated through simulation using a modified IEEE 69-bus system which is divided into three districts with different load variability characteristics.

关键词： Optimal island partition Distributed generation Island power dispatch Active distribution networks Photovoltaic Electric vehicles