Advanced Materials Research Vols. 160-162

Abstract: A typical parameterized model of pipe axis’ secondary necking in hot extrusion process was built，and the evaluation index of forming effect was proposed. Through using revised constitutive equation in Ansys model combining the method of numerical simulation, several mainly hot extrusion process parameters’ influence on forming effect were analyzed, such as friction, temperature and extrusion speed. The prediction equation of forming effect was worked out by numerical fitting, which provided a feasible way to get the better parameters in hot extrusion process. The experiment shows that the parameters obtained from equations can have a good guide on pipe axis and also other similar workpiece’ s hot extrusion process.

Abstract: There are many advantages of magnesium alloy such as light mass, nonrattling and electromagnetic interference shield. Yet, its ductility was poor at room temperature and plastic forming was difficulty due to its close-packed hexagonal structure. In this paper, the superplasticity of magnesium alloy AZ91D was explored and the relationship between flow stress and true strain were achieved at different temperature by tensile tests. It was found that the flow stress of AZ91D as cast was less than 20MPa at 340-450°Cand superplastic deformation could be used to manufacture magnesium alloy parts. Utilized superplastic air bulking mold, AZ91D seamless pipes with variable cross-section were manufactured successfully based on process parameters being optimized. Moreover, the relationship between loading path of internal pressure and wall thickness was analyzed also.

Abstract: In this study, regenerated silk fibroin (RSF, from Bombyx mori) nanofibers with smooth surface had been successfully prepared via electrospinning, as shown by SEM and then as-spun fibers were induced under 75% ethanol vapor. We aimed to investigate the morphology and structure change of 75% ethanol vapor-induced silk fibroin nanofibers. To determine any difference in surface topographies, the nanofibers were inspected using atomic force microscope (AFM) and the results showed that after inducement of 75% ethanol vapor for 24 h, the surface of fibers became rough. Differential Scanning Calorimetry (DSC) analysis indicated that electrospun SF nanofibrous membranes typically took silk I form and 75% ethanol vapor-induced SF nanofibrous membranes took silk II structure. These results suggested that 75% ethanol vapor inducement could be an attractive alternative to expand the application of RSF.

Abstract: A novel amperometric immunosensor for the determination of alpha-fetoprotein (AFP) was constructed using multi-wall carbon nanotubes modified glass carbon electrode.thionine as the mediator,were immobilized by DNA throngh the layer-by-layer method. Thionine was first fabricated on carbon nanotubes modified glass carbon throngh 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide(EDC/NHS).then a negatively charged DNA film was absorbed on the positively charged thionine,and the DNA was uesd as cross-linker to immobiled amount thionine.nano-Au-was used to immobilized anti-AFP.The electrochemical sensor have a relatively low detection limit of 0.02ng/ml.

Abstract: Globe warming caused by Green House Gas emissions has been threatening human life and development, and the CO2 emission associated with production and use of packaging plays an important role in atmospheric greenhouse effect. The carbon footprints of both plastic-based packaging and honeycomb paperboard were studied in this article, and two typical examples of green & low carbon packaging solution for Haier air condition and automatic washing machine were illustrated respectively in conclusion. The analytical results indicated that the paper packaging material can not only reduce carbon dioxide emission dramatically, but is also a technical way for carbon storage. Therefore, replacement of plastic-based cushion packaging with honeycomb paperboard material is a green and low carbon development road with which it can provide a feasible and technical solution with environment protection, material saving and GHG emission reduction for packaging industry.

Abstract: Kinetics of vulcanization of natural rubber coagulated by microorganisms (NR-m) was studied with the use of a vulcameter. In the induction period of vulcanization, the time t0 of NR-m is shorter than that of natural rubber coagulated by acid (NR-a), and the rate constant k1/a of NR-m are greater than that of NR-a. Both the curing periods of NR-m and NR-a consist of two stages. The first stage follows first-order reaction. The rate constants k2 of NR-m in the first stage are greater than that of NR-a at the same temperature, and so are the activation energy E2. The second stage (end stage of the curing period) does not follow first-order reaction, and the calculated reaction order n of NR-m is in the range of 0.82-0.85, and that of NR-a is in the range of 0.64-0.72. The rate constants k3 of the second stage for NR -m are greater than that of NR-a at the same temperature, and so is the activation energy E3.

Abstract: From the prospect of environmental optimization the paper establishes a two-dimensional structure of low-carbon efficiency model firstly, with which the different efficiency of economic development comes down to four models. Then the paper builds evaluation index system on low-carbon by taking the CCR model of DEA method as the main analysis approach. On the basis of the above the paper researches on the ecological economy efficiency of 7 economic regions in China from the three levels，namely economic growth efficiency, environmental optimization efficiency and low-carbon efficiency. Eventually, through index evaluation process on the development situation of the above-mentioned economic regions from 2006 and 2007 this article puts forward strategic development policy recommendations advices for the derived results.

Abstract: ITO thin films used in PTCDA/Si detector should be made at low temperature for low temperature resistance of substrate. ITO thin films were deposited at low temperature by RF magnetron sputtering. Properties of ITO thin films such as conductivity and transmission measured by 4 point probe and UV spectral photometry respectively. The results show that the sputtering pressure is an important parameter in the deposition of indium tin oxide（ITO） thin films, which affects the properties of ITO films. The optimized parameter for preparation of ITO thin films at low temperature are sputtering pressure 0.45 Pa, sputtering power 45W. Meanwhile, the post-annealing is not necessary.

Abstract: In this paper, in order to eliminate the adverse effects of blue-stain on the wood surface appearance and improve wood mechanical properties, wood compression process and wood thermal treatment process were applied into the physical modification of blue-stain Masson Pine (Pinus massoniana). The test results showed that when the specimens are hot-pressed with the compression rate of 50%, and then were heat-treated at 220°C for 2h, the wood surface color and dimension stability could be improved significantly. Moreover, the surface hardness and the compression strength of the compressed-thermal treated wood could be increased significantly compared to the untreated blue-stain wood. Based on this study, the biological properties of the specimens after compression and thermal treatments will be investigated in the future.

Abstract: Based on the Unified Strength Theory(UST),the ultimate load calculation formula for the recycled aggregate concrete-filled steel tubular short columns is derived in this paper,in which the decrease of longitudinal stress because of the hoop tensile tension is considered. The influence of intermediate principal stress on the ultimate load is studied and the failure mechanism is also discussed. The results show that the intermediate principal stress have important effect on the ultimate load which increases with the strength parameter .Through the comparison between the experimental results and the calculating results obtained in this paper,the deviation is small,and it shows that the formula have significance in exerting material potential.