Advanced Materials Research Vols. 690-693

Abstract: Silicon carbide ceramic composite filter membrane materials were prepared by dry pressure molding and synchronous sintering process at sintering temperature of 1300oC for 3h. and research the influence of on the molding pressure structure of SiC filtration membrane,effect of particle size on porosity, average pore size and filter pressure drop of filtration membrane, SEM was performed to examine the morphology, The porosity ,average pore size and filter pressure drop of filtration membrane were tested by Archimedes method ,bubble point method and filter pressure drop instrument. It is demonstrated that while the molding pressure (F) varied from 1MPa to 10MPa, the filter membrane material achieved preferable morphology and best performance when F equals to 5MPa. Under this modeling pressure, while silicon carbide particle size increased from 1 to 23μm, the pore ratio decreased from 48.0% to 36.2% and the average pore size increased from 0.35μm to 9.4μm, while the air gas velocity changed from 0 to 0.112m/s, the filter pressure drop increased, when the velocity is stable, the filter pressure drop reduced as the silicon carbide particle size.

Abstract: Reinforced soil has been among the most effective soil modification materials. Its use has been expanded rapidly into civil engineering, geotechnical engineering and pavement engineering. Reinforcing subgarde in pavement systems has always been an issue. This study focuses on effect of fiber inclusion on the strength of subgrade material. Plastic fiber was used for this investigation. Fiber contents and aspect ratio have been changed during these tests. The fiber percentage varied from 0 % (for unreinforced samples) to 4%. Silty clay was used as sub grade material. Unconfined compression tests were carried out to investigate behaviour of the composite under different condition. The fiber length and fiber content found to play important rule on the strength of composite. Furthermore it was observed that ductility of sample increased by fiber inclusion.

Abstract: Al₂O₃-SiO₂-ZrO₂ composite sol was prepared with inorganic precursors by sol-gel method. Using Al₂O₃ ceramic tubes as supporter, well-surfaced Al₂O₃-SiO₂-ZrO₂ composite microfiltration membrane was achieved by the film-forming technique of pretreatment of the ceramic tube supporter, 3 times recycled dipping-drying-sintering, being dried at 50°C thermostatic water bath and sintered at 900°C.

Abstract: Nitinol alloy is used widely in biomedical science because of their good performances. The radial support force, biocompatibility and fatigue performance of nitinol alloy blood stent meet the requirement correctly. With the development of computer simulation technology, the stent structure, materials and so on will get further improvement and innovation under the help of statuses on the finite element analysis and blood flow dynamics simulation of nitinol alloy stent.

Abstract: The NiO_x/Bi₂WO₆ photocatalyst with p-n heterojunction structure was synthesized. And the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). It was found that the RhB degradation rate with NiOx/Bi2WO6 was 1.62 times as great as that with the Bi2WO6 under visible light (λ>400 nm) by the photocatalytic measurements. The enhanced photocatalytic performance of the NiOx/Bi2WO6 sample was attributed to the improved separation efficiency of photogenerated hole-electron pairs generated by the p-n heterojunction between Bi2WO6 and NiOx.

Abstract: Effect of adding CaCO₃ on the microstructure and properties of corundum was studied, with corundum modified by adding CaCO₃ powder, by means of XRD, SEM etc. The experimental results show that when the quantity of CaCO₃ powder is not more than 14.1wt%, would obtain corundum-calcium hexaluminate composite aggregate. When a little hexaluminate is generated, it would not increase porosity significantly but closed porosity increase slightly, and the heat conductivity is lower than tabular corundum. Calcium hexaluminate in aggregate grow well and are flakes. There are large numbers of small pores, and distributed uniformly. Composite aggregate has preferable performance of sintered and low thermal conductivity when hexaluminate generative capacity is about 27%.

Abstract: The chitosan/rectorite composite was prepared and characterized by XRD. The interlayer distance of rectorite was enlarged from 2.53 nm to 3.01 nm. Congo red (CR) was selected as a model anionic dye and the adsorption tests of CR onto chitosan/rectorite composite were carried out. The results showed that the CR adsorption process is dependent on pH and initial CR concentration and temperature. The maximal CR uptake by chitosan/rectorite composite was 73.8 mg g-1 in the test. Adsorption kinetics studies indicated that the sorption processes were better fitted by pseudo-second order equation.

Abstract: With the progress of DNA computing and nanotechnology, DNA/AuNP conjugation becomes an emerging interdisciplinary field. In this paper, a novel DNA computing model based on DNA/AuNP conjugation is developed to solve a maximum independent set problem (MIS). Making use of the hybridization between long DNA strands and short strands conjugated with gold nanoparticles, a series of searching process is implemented. After that, based on the number of DNA/AuNP conjugation on one DNA strand, the answer of the MIS is obtained. To verify the proposed algorithm, a simple paradigm is calculated by using the DNA computing model. In this model, there are some significant advantages such as easy detecting, and controllable automation. This work may demonstrate that DNA computing has the great potentiality in huge parallelism computation.

Abstract: Gadolinium–doped ZnO nanocrystalline powders were prepared by hydrothermal method using ionic liquid (1-heptyl-3-methyl imidazole bromide) as template. The crystal structure, grain size and optical properties of the samples were characterized by X-ray diffractometry, scanning electron microscopy and UV-Vis spectroscopy. The photocatalytic degradation of KN-R dye under simulated sunlight was chosen as a model reaction to evaluate the photocatalytic activities of the undoped and doped ZnO nanocrystalline catalysts. It was shown that Gadolinium was successfully doped into ZnO powders, and thus showing enhanced performance in degradation of KN-R.

Abstract: Columnar crystaldendriteequiaxial dendritescolumnar crystalNanosized powder was synthesized by direct-reactive precipitation process using a stoichiometrical mixture of TiCl₄, BaCl₂ as the reactants while NaOH as precipitant. Under the ratio of Ba to Ti is 1.02, PH=13, three reaction temperature of 70°C, 80°C and 90°C were conducted respectively. Morphology and phase structure of powder were investigated, and the influence of reaction temperature on powder morphology was discussed. The result indicates that synthesized powder is single cubic BaTiO₃ and contains no impurities. BaTiO₃ powders generally show spherical, and average particle size decreases with increasing reaction temperature. When reaction temperature is 80°C, BaTiO₃ powder has best uniformity and dispersivity with the diameter of 80-100nm. The influence of reaction temperature on powder particle size can be attributed to the corporate contribution of nucleation and growth rate. Polyglycol as surface active agent has a significant effect in restraining agglomeration.