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Influence of Surface Structure of Platinum Electrodes on Electrooxidation of CO

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Chemical Research in Chinese Universities 2003年第4期19卷 474-480页

作者： XIA Xing-hua zhang dai SONG Yan-yan State Key Laboratory of Coordination Chemistry Institute of Analytical ScienceNanjing UniveristyNanjing 210093P.R.China

The oxidation of CO on platinum electrodes in an acid solution was studied with the conventional electrochemical methods and the on-line electrochemical mass spectroscopy. It was found that this reaction is strongly determined by the surface morphology of platinum. The pretreatment of platinum electrodes can change the surface properties dramatically, in consequence it can improve the electrocatalytic activity towards the electrooxidation of CO. The existence of surface active sites on the roughened platinum electrodes can be used to explain its high electrocatalysis towards the oxidation of CO.

关键词： Electrocatalysis Platinum Surface property Mechanism

Complete Composition Tunability of Cu(Ni)-Ti-Zr Alloys for Bulk Metallic Glass Formation

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Journal of Materials Science & Technology 2009年第1期25卷 39-47页

作者： Ze-xiu zhang Chun-li dai Jian Xu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences 72 Wenhua Road Shenyang 110016 China

In the Cu-Zr-Ti ternary system, a new composition zone of bulk metallic glasses （BMGs） formation was discovered, locating at the 55-57 at. pct Cu, 30-31 at. pct Ti and 13-14 at. pct Zr, and near Cu-Ti binary subsystem rather than the Cu-Zr binary. For these alloys, BMG rods of 2 mm in diameter can be fabricated by using copper mould casting. It is expected that these 13MG-forming alloys correlate with （L →CuTi＋Cu2TiZr＋Cu51Zr14） eutectic reaction that the undercooled melt undergoes during solidification. Adopting ＂3D pinpointing approach＂, compositional dependence of glass-forming ability （GFA） in Cu（Ni）-Ti-Zr pseudo ternary system was revisited. Optimized BMG-forming composition is located at Cu50.4Ni5.6Ti31Zr13, with a critical diameter of 6 mm for complete BMG formation. Its GFA is significantly superior to Vit 101 （Cu47Ni8Ti34Zr11） previously developed by Caltech group. The effect that the GFA of the ternary base alloy was improved by substitution of Ni for Cu is attributed to a role of retarding the crystallization of Cu51Zr14 intermetallics.

关键词： Bulk metallic glasses Amorphous alloys Eutectic Copper

Preparation and Identification of Angelica sinensis Polysaccharide-iron Complex

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Chemical Research in Chinese Universities 2005年第6期21卷 668-672页

作者： WANG Kai-ping zhang Yu dai Li-quan Faculty of Pharmacy Tongfi Medical College Huazhong University of Science and Technology Wuhan 430030 P. R. China

Angelica sinensis polysaccharide（ASP） was extracted from Angelica sinensis by boiling water. An Angelica sinensis polysaccharide-iron complex（APC） was prepared under the alkaline condition by adding a ferric chloride solution to the ASP solution. Then some identifiable properties of the complex were studied. The content of iron（ Ⅲ ） in the complex was determined with iodometry. The thermal property, the microscopic structure, the spectral characteristics, and N, C, H contents of the complex were examined by a variety of techniques including DSC, TEM, IR, NMR, and elemental analysis. The content of iron（ Ⅲ ） in the complex ranges from 10% to 40%. The DSC result shows that the melting point of the complex is about 450 ℃. The TEM result shows that the complex has an iron（ Ⅲ ） core（β-FeOOH core） linked by hydroxy and oxy bridges, with the polysaccharide chains attached to the surface of the core. The IR and NMR results also show that there is a β-FeOOH core in the complex. The elemental analysis shows that the contents of N, C, H in the complex are, respectively, lower than those of N, C, H in ASP. All our studies indicate that the APC consists of a β-FeOOH core surrounded by ASP.

关键词： Preparation Identification Angelica sinensis polysaccharide Angelica sinensis polysaccharide-iron complex

A high strength pH responsive supramolecular copolymer hydrogel

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Science China(Technological Sciences) 2017年第1期60卷 78-83页

作者： WANG Qing zhang YinYu dai XiYang SHI XiaoHuan LIU WenGuang School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional Materials Tianjin University Tianjin 300354 China

Constructing high strength pH sensitive supramolecular polymer hydrogel remains very challenging due to the unavoidable network swelling caused by ionization of acid or basic groups at a specified *** this work,we proposed a simple and very convenient approach to fabricate high strength pH responsive supramolecular polymer(SP) hydrogels by one-pot copolymerization of N-acryloyl glycinamide(NAGA) and 2-vinyl-4,6-diamino-1,3,5-triazine(VDT),two feature hydrogen bonding *** these PNAGA-PVDT SP hydrogels obtained,the hydrogen bonding of NAGA was shown to play a dominant role in reinforcing strength,while the hydrogen bonding of diaminotriazine served as a pH sensitive *** pH 3,the mechanical properties of PNAGA-PVDT hydrogels decreased to a different extent due to the breakup of hydrogen bonding;in contrast,the hydrogel resumed the original strength while pH was raised to 7.4 because of reconstruction of hydrogen *** the selected pH range,the PNAGA-PVDT hydrogels exhibited up to 1.25 MPa tensile strength,845% breaking strain,69 kPa Young's modulus and 21 MPa compressive *** novel high strength pH-responsive SP hydrogels may find applications in biomedical and industrial fields.

关键词： high strength pH responsive supramolecular polymer hydrogel

Self-nucleation Effect of Crystallization with Various Nucleating Agents

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Chinese Journal of Polymer Science 2023年第12期41卷 1912-1920,I0009页

作者： dai zhang Rui-Jun Zhao Gui-Qiu Ma Zhe Ma Tianjin Key Laboratory of Composite and Functional Materials and School of Materials Science and EngineeringTianjin UniversityTianjin 300072China

In this work,the self-nucleation effect on crystallization was studied for polypropylene with various nucleating *** talc was employed to accelerate crystallization of monoclinic α-crystallites,while N,N′-dicyclohexyl-2,6-naphthalenedicarboxamide TMB-5 was used to accelerate the crystallization kinetics and also induce formation of trigonal β-*** induce self-nucleation effect,the occurrence criterion was assessed by the transition temperatures from various domains and the available temperature *** importantly,the resulting influences of self-nucleation effect were quantified by the change of crystallization kinetics and the potential polymorphism *** was found that the α-nucleating agents of talc broadened the temperature window for inducing Domain Ⅱ by elevating the transition temperature from Domain Ⅰ to Domain Ⅱ.Although β-nucleating agent(β-NA)of N,N′-dicyclohexyl-2,6-naphthalenedicarboxamide TMB-5 elevated cooling crystallization temperature obviously,the temperature window for Domain Ⅱ was *** should be emphasized that in presence of β-NA TMB-5,the self-nucleation effect enhances the crystallization of α-crystallite,which show the competition with β-NA *** last,the ternary PP/talc/TMB-5 blend was prepared with the same amounts of α-NA talc and β-NA TMB-5 and it exhibits a similar self-nucleation effect of crystallization,indicating the dominant role of β-NA TMB-5.

关键词： Crystallization Kinetic Polymorphism

Investigation of the Interaction Between the Free Surface and A Semi/Shallowly Submerged Underwater Vehicle

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China Ocean Engineering 2024年第5期38卷 771-784页

作者： ZHU Xin-yao HAN Yue YANG Pu zhang dai-yu School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China Kunming Shipborne Equipment Research&Test Center Kunming 650051China

The present study aims to investigate the interaction between the free surface and a semi/shallowly submerged underwater vehicle,especially when the submergence depth h is smaller than 0.75D(D:submarine maximum diameter).In this respect,the straight-ahead simulations of the generic SUBOFF underwater vehicle geometry are conducted with constant forward velocities using the Unsteady Reynolds-Averaged Navier-Stokes(URANS)equations with a Shear-Stress Transport(SST)k-ωturbulence model in commercial code Fluent,at submergence depths and Froude numbers ranging from h=0 to h=3.3D and from Fn=0.205 to Fn=0.512,*** numerical models are verified against the existing experimental *** analysis of the obtained results indicates that in the case of the semi and shallowly submerged underwater vehicle(UV),both the submergence depth and forward velocity have a great effect on the behaviors of hydrodynamic forces acting on the *** magnitude of maximum total resistance may reach almost five times the value of resistance exerted on the totally submerged *** the forces acting on the UV and the generated waves when the submergence depth h is smaller than 0.75D are significantly different from those whenr h is larger than *** conclusions can be used as reference for future research on near free surface motions of underwater vehicles and the design of small water-plane area twin hull.

关键词： free surface effect underwater vehicle hydrodynamic characteristics SUBOFF geometry wave-making computational fluid dynamics(CFD)

Unthermal Hawking Radiation from a General Stationary Black Hole

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Communications in Theoretical Physics 2008年第2期49卷 379-381页

作者： zhang Yong-Ping dai Qian LIU Wen-Biao Department of Physics Institute of Theoretical Physics Beijing Normal University Beijing 100875 China

Using Damour-Ruflini＇s method, Hawking radiation from a general stationary black hole is investigated again deeply. Considering the back reaction of the particle to the space-time and energy conservation, we find that the radiation is not exactly thermal and can take out information from the black hole. This can be used to explain the information loss paradox, and the result is consistent with the works finished before.

关键词： Hawking radiation stationary black hole back-reaction information loss paradox unitary theory

Mechanical Properties of QFP Joints Soldered with SnAgCu and SnPb Solders

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 596-600页

作者： XUE Peng XUE Songbai ZENG Guang zhang Liang dai Wei College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

With the development of lead-free solder alloys, the investiagtion focusing on the relibility of lead-free solders are essential. Since the reliability database of lead-free solder joints needs to be further supplied, the creep behavior of SnAgCu soldered joints on Quad Flat Package （QFP） devices under thermo cycling load are studied in this paper, compared to conventional SnPb solder, by finite element simulation based on Garofalo-Arrhenius creep model. Meanwhile, the mechanical properties of SnAgCu and SnPb soldered joints in the pitches of QFP devices are also carried out by means of tensile test. The results indicate that the values of strain and stress of SnAgCu soldered joints were all smaller than those of SnPb under thermal cycling, and the tensile strength of the joints soldered with SnAgCu solder was higher than that of SnPb, which means the reliability of the joints soldered with SnAgCu solder is better than SnPb soldered joints. As the fracture surface morphology of the soldered joints compared, SnAgCu soldered joint presented ductile fracture, while the fracture mechanism of SnPb solder joints displayed both brittle and ductile fracture. Above all, the experimental results is in accord with that of simulation, which will provide guidance for reliability study and application of lead-free solders.

关键词： creep model finite element analysis Quad flat package (QFP) devices mechanical properties

Three-dimensional ordered macroporous platinum-based electrode for methanol oxidation

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Chinese Science Bulletin 2006年第1期51卷 19-24页

作者： zhang dai GAO Wei XIA Xinghua CHEN Hongyuan Key Laboratory of Analytical Chemistry for Life Science Department of Chemistry Nanjing University Nanjing 210093 China

In this paper, three-dimensional ordered macroporous platinum catalysts with high real sur- face area were synthesized using the inverted col- loidal crystals template technique and have been employed for the electrooxidation of methanol. The morphology and electrocatalytic behavior of the po- rous Pt electrodes were investigated with atomic force microscopy and electrochemical techniques. For the same amount of Pt deposited, the real sur- face areas of the electrodes are 9.16 and 8.00 cm2 for the porous electrodes with pore size of 320 and 500 nm respectively, which are more than 5 times larger than the directly deposited Pt electrode (1.4 cm2). The pore size effect on the methanol elec- trooxidation was investigated by testing low concen- tration solution of methanol and porous materials with different pore sizes. The synthesized macroporous Pt electrode shows high stability toward the electrooxi- dation of methanol and is promising for the direct methanol fuel cell.

关键词：大孔电极铂甲醇电催化氧化