Advanced Materials Research Vols. 197-198

Abstract: In order to control the machining process of Direct-Write based on Near-field Electrospinning automatically, an automatic programming system used for an open architecture CNC system is proposed in this paper. This system descirbes the machining trajectory via the 2D CAD drawing, from which the data is extracted by the system. According to the processing parameters, the data is classified and reordered, and NC codes are automatically generated. The system solves the problem in integrating the design and machining, makes it more convenient to experimental research and realizes patterned fabrication of micro/nano-structure,which provides a good experimental base for the development of electrospinning technology.

Abstract: The corrosion properties of several common artificial reef materials were studied using electrochemical methods and by measuring corrosion rates in estuary water and seawater. Experimental results show that the 6063 aluminum alloy can be a reef construction material only in low velocity estuary water. Copper in seawater has high corrosion potential and can be passivated, but the high velocity water will destroy the passivation film and decrease the corrosion resistance of copper. Copper is a suitable reef material in low flow seawater and estuary water. With low open potential, high anode current and extensive corrosion, Q235 steel is only suggested as artificial reef material if applying sacrificial anode protection. Pine block and granite are natural materials whose degradation products won’t harm the environment, but the pine block has short service life while granite has a minimal corrosion rate. PVC has small corrosion rate but leaches toxic substances after degradation, so it is not suitable for wide-ranging use.

Abstract: This study describes experiments of testing the color stability of heat-treated okan sapwood samples. Heat-treatment was done at 160°C,180°C,200°C,220°C during 4 hours, under steam. series of experiments were carried out to investigate the color stability of heat-treated okan sapwood compared to untreated wood during 100 hours xenon light irradiation. Color measurements during accelerated weathering were made at intervals throughout the test period. The results are presented in △E* and L* a* b*coordinates according to the CIE(1976)L*a*b* parameters color system. Better photo-stability in terms of color changes was recorded for heat-treated wood compared to the untreated one. The properties of heat treated wood are involved in the heat-treated wood resistanceagainst xenon light under experimental conditions.

Abstract: Effect of crystals size, surface area, pore size and porosity of hydroxyapatite microspheres on the loading ability of bovine serum albumin was studied in this paper. The surface morphology, specific surface area and porosity of hydroxyapatite microspheres were characterized by scanning electron microscope, specific surface area and pore size analyzer, respectively. The concentration of BSA in aqueous solutions both before and after adsorption was determined by ultraviolet-visible spectrophotometer. The results indicated that the adsorption behavior of bovine serum albumin appeared to obey the Langmuir-type isotherm model. Fast adsorption appeared at the beginning, and then decreased gradually. Hydroxyapatite microspheres calcined at 600°C had the maximum capacity, and those calcined at 800°C showed lower adsorption ability. The loading ability of hydroxyapatite microspheres depended on its crystal size, specific surface area, pore size and porosity, etc.

Abstract: In this paper, a novel biodegradable and fluorescent polymer: fluorescein-polylactide (FL-PLA) was synthesized by FL and lactide in the method of ring-opening polymerization with the catalysis of Sn(Oct)₂ under 130°C . The structure and molecular weight of FL-PLA were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (¹H-NMR) spectroscopy, and gel permeation chromatography (GPC). The molecular weight of FL-PLA increased from 9.03×10³ to 21.24×10³ with decreasing the amount of FL and kept a narrow distribution. The result of differential scanning calorimeter (DSC) showed that T_g increased from 52 to 72°C with increasing the molecular weight of polymer. Moreover, the average number content of FL in each molecular chain decreased from 0.96 to 0.81 with decrement of the amount of FL. Furthermore, FL-PLA showed the fluorescence property, and the fluorescence intensity could be controlled by the amount of FL. The FL-PLA nanoparticles were prepared by mixing the good and poor solvent, and the diameter was about 3 μm with regular spherical morphology.

Abstract: The structure and mechanical properties of A. yamamai, A. perny and B. mori silk fibroin films irradiated by gamma ray with various doses of 0, 25, 50, 100 and 200 kGy, respectively were determined by XRD, FT-IR, DSC and Instron 3365 equipment. Results showed that the aggregation structure and molecular conformation of A. yamamai, A. perny and B. mori silk fibroin films irradiated by gamma ray with those doses mentioned above were not significantly changed. However, with the increase of radiation intensity, the thermal stability of silk fibroin films declined slightly, and the breaking strength and extensibility reduced significantly, due to the breakdown of parts of secondary bonds and covalent bonds. These results suggested that, when these silk fibroin materials were sterilized by gamma irradiation, smaller radiation doses should be used, otherwise irreversible damages on these materials would be caused.

Abstract: The effects of Nb addition on microstructures, Young’s moduli, tensile properties of Ti-30Ta-xNb (x = 21, 24, 27, 30, wt. %) alloys were investigated in this study. The results show that dual phases containing β phase and a little α" martensite were observed when x = 21 and 24, whereas single β phase is present when x = 27 and 30. A minimum Young’s modulus of 52.13 GPa was obtained in Ti-30Ta-21Nb alloy. Ti-30Ta-xNb alloys exhibit high strength-to-modulus ratios, showing their great potentials to develop as new candidates for biomedical applications.

Abstract: The artificial prosthesises currently used are only different in the femoral head size, neck length and stem thickness, but there is not any individualized prosthesis. At present, prosthesis looseness is the main problem of artificial femoral replacement, and individual matching level of joints is the bottleneck of restricting prosthesis replacement surgery. If we can design and produce corresponding individual artificial joints according to the patient's bone shape and bio-mechanical characteristics, there will be a significant impact on human health and medical treatment. In this paper, I complete the reconstruction process of the CT three-dimensional finite element model of femur, with the help of powerful image processing functions of medical imaging system MIMICS. I load force with the experimental data provided by the VIMS laboratory, analyze the biomechanical properties of femur and investigate the influence of anteversion angle parameter on mechanical properties.

Abstract: Micro-EDM technology has the advantages of no-contact and no-cutting force, it has been used in many fields. In order to use micro-EDM to machine proprietary micro array holes, which needs high precise of hole spacing and consistent hole diameter, a new macro-micro dual-drive system of micro-EDM have been made. It uses macro drive to move to a place, measures the error with the high precise grating, and uses micro drive to compensate the error. Online measurement proved that this method has important value if it will be used in micro-EDM.