Mingshi SONG and Jincai YANG (Research Institute of Polymeric Materials
,
Beijing University of Chemical Technology
,
Beijing
,
100029
,
China)Yiding SHEN(North West Institute of Light Industry
,
Shanxi Xianyang
,
712087
,
China)
材料科学技术（英文）
It is shown theoretically that the viscoelasticity of polymer melts is determined by three combining factorst they are the primary molecular weight and its distribution, the number of entanglement sites on polymer chain and the sequence distribution of constituent chains in entanglement spacings. A unified quantity for the three combing factors is the average constrained dimensional number of constituent chains in the long entanglement spacings (v). A new relation of v to the primary molecular weight and the number of testing polymers were derived from the multiple entanglement and reptation model, and a new method for determining v was proposed. The dependences of linear viscoelastic functions on the primary molecular weight and its distribution were derived by the statistical method. When Mn=6Me to 18 Me, the values of (v) can range from 3.33 to 3.70. Their values are in a good agreement with the experiment data, and it can slightjy vary with the different species of polymers and the different ranges of molecular weight of polymers
关键词:
Xufeng NIU
,
Yuanliang WANG
,
Yanfeng LUO
,
Juan XIN
,
Yonggang LI
材料科学技术（英文）
The new generation of biomaterials focuses on the design of biomimetic polymeric materials that are capable of eliciting specific cellular responses and directing new tissue formation. Since Arg-Gly-Asp (RGD) sequences have been found to promote cell adhesion in 1984, numerous polymers have been functionalized with RGD peptides for tissue engineering applications. This review gave the advance in RGD modified biomimetic polymeric materials, focusing on the mechanism of RGD, the surface and bulk modification of polymer with RGD peptides and the evaluation in vitro and in vivo of the modified biomimetic materials.
关键词:
Arg-Gly-Asp (RGD)
,
null
,
null
WADSWORTH Jeffrey and FLUSS Michael(Chemistry and Materials Science Directorate
,
Lawrence Livermore National Laboratory
,
Livermore
,
CA 94551)
金属学报(英文版)
The role of the National Laboratories is summarized from the era of post World War II to the present time. The U.S. federal government policy for the National Laboratories and its influence on their materials science infrastructure is reviewed with respect to .determining overall research strategies, various initiatives to interact with industry (especially in recent years),building facilities that serve the nation, and developing leading edge research in the materials sciences. Despite reductions in support for research in the U.S. in recent years, and uncertainties regarding the specific policies for Research &Development (R&D) in the U.S., there are strong roles for materials research at the National Laboratories. These roles will be centered on the abilities of the National Laboratories to field multidisciplinary teams, the use of unique cutting edge facilities, a focus on areas of strength within each of the labs,increased teaming and partnerships, and the selection of motivated research areas. It is hoped that such teaming opportunities will include new alliances with China, in a manner similar, perhaps, to those recently achieved between the U.S. and other countries.
关键词:
: U.S. Materials Science. U.S. National Laboratories and Facilities
,
null
G.Q. Zhang
金属学报(英文版)
The status of research, development of superalloys and materials processing & fabrication technologies for aero-engine applications in China Aviation Industry, with an emphasis on recent achievements at BIAM including directionally solidified and single crystal superalloys for blade and vane applications, wrought superalloys for aero-engine disks and rings, and powder metallurgy (PM) superalloys for high performance disk applications were described. It was also reviewed the development of new class of high temperature structural materials, such as structural intermetallics, and advanced material processing technologies including rapid solidification, spray forming and so on. The trends of research and development of the above mentioned superalloys and processing technologies are outlined. Cast, wrought and PM superalloys are the workhorse materials for the hot section of current aero-engines. New high temperature materials and advanced processing technologies have been and will be the subject of study. It is speculated that high performance, high purity and low cost superalloys and technologies will play key roles in aero-engines.
关键词:
superalloy
,
null
,
null
新型炭材料
The state-of-the-art research and development of various carbons for possible application as the electrode material in electrochemical capacitors (ECs) are summarized. The main factors affecting the properties of ECs are carefully reviewed, from the material characteristics such as specific surface area, pore size distribution and pore volume, surface functional groups and graphitic orientation of the carbon materials, to the electrode characteristics and electrochemical aspects such as electrode preparation process, electrode density and thickness, electrode conductivity and pseudo-capacitance, etc. In particular, an overview is given of the most recent progress in electrochemical capacitors using carbon nanotubes as the electrode material and the prospect of their use in this application is highlighted.
关键词:
electrochemical capacitors;carbon electrode;carbon nanotubes;double-layer capacitors;activated carbon;nanotube electrodes;supercapacitor electrodes;organic electrolyte;deposition;fiber
Biomaterials
Synthesis of anticancer polymeric materials plus their biological applications is one of the most charming and active research areas in biological functional materials. However, the predominant mechanisms for controlling cancer cell viability are not yet clear. In this work, cell culture polymeric materials co-immobilized with death signal proteins interferon-gamma (IFN-gamma)/tumor necrosis factor-alpha (TNF-alpha) on the surface were prepared by photochemical method to develop an anticancer polymeric drug model. Various characterizations on the microstructures and compositions, including the Fourier transform infrared spectroscopy, UV absorption spectroscopy, fluorescence measurement, atomic force microscopy, and electron spectroscopy for chemical analysis, were performed. For addressing the biological applications, we investigated systematically the death pathways of HeLa cells attached onto the drug model by means of a series of cell-biology techniques. It was demonstrated that the IFN-gamma plus TNF-alpha co-immobilized on the polymeric material surface exhibited more notable inhibitive effects than the free IFN-gamma plus TNF-alpha, and the induced HeLa cells were mainly along apoptosis-like PCD with the translocation of EndoG from the cytoplasm to the nucleus. These findings indicate that the polymeric drugs with the co-immobilized IFN-gamma plus TNF-alpha may offer significant potentials for therapeutic manipulation of human cervical cancer. (C) 2011 Elsevier Ltd. All rights reserved.
关键词:
Co-immobilized IFN-gamma plus TNF-alpha;Polystyrene material;HeLa;EndoG;tumor-necrosis-factor;nf-kappa-b;ifn-gamma;interferon-gamma;endonuclease-g;factor-alpha;apoptosis;activation;micelles;p53
新型炭材料
Electrochemical capacitors (ECs) store energy in eletric double-layers formed along the interface of electrode material and electrolyte, this produces an extremely large capacitance compared with the traditional capacitors. The fundamental principles of electrochemical capacitors are briefly introduced, and the key materials used like electrode materials, electrolytes, separator and current collector materials are summarized. Electrochemical capacitors with pseudocapacitance, such as metal oxides, polymers and hybrid capacitors, are also discussed. The characteristics, possible application fields, the development state, the future R&D prospects for electrochemical capacitors are highlighted.
关键词:
electrochemical capacitors;supercapacitors;storage of electric energy;principles
J Y Wu
,
Z.M. Tang
,
W Shi andR.Z. Wang (Institute of Refrigeration and Cryogenics Engineering
,
Shanghai Jiao Tong University
,
Shanghai 200030
,
China)
金属学报(英文版)
A transient method with rectangular pulse heating has been developed to measure the thermal conductivity of highly porous materials such as activated carbon, zeolite and silica gel. By this method the thermal conductivity can be measured quickly and accu-rately. In this paper, a set of automatically controlled testing equiptnent is presented.The measuring method is analysed. The thermal conductivities of some samples, such as activated carbon and zeolite, are measured by the equipment. A group of useful data has been obtained.
关键词:
thermal conductivity
,
null
,
null
Journal of Physics-Condensed Matter
The immense interest in carbon nanomaterials continues to stimulate intense research activities aimed at realizing carbon nanowires, since linear chains of carbon atoms are expected to display novel and technologically relevant optical, electrical and mechanical properties. Although various allotropes of carbon (e. g., diamond, nanotubes, graphene, etc) are among the best-known materials, it remains challenging to stabilize carbon in the one-dimensional form because of the difficulty of suitably saturating the dangling bonds of carbon. Here, we show through first-principles calculations that ordered polymeric carbon chains can be stabilized in solid Li(2)C(2) under moderate pressure. This pressure-induced phase (above 5 GPa) consists of parallel arrays of twofold zigzag carbon chains embedded in lithium cages, which display a metallic character due to the formation of partially occupied carbon lone-pair states in sp(2)-like hybrids. It is found that this phase remains the most favorable one in a wide range of pressures. At extreme pressure (larger than 215 GPa) a structural and electronic phase transition towards an insulating single-bonded threefold-coordinated carbon network is predicted.
关键词:
augmented-wave method;crystal-structure;high-pressure;polyacetylene;transition;nitrogen;thsi2;boron
