Papers by Author: Kazuharu Koide

Abstract: Magnetic nanoparticles are widely used in magnetic fluid, magnetic grinding materials, magnetic controllers, magnetic sensors, biomedicine fields and so on. Recently, more and more attentions were focused upon DDS (Drug Delivery System). In this study, Magnetite nanoparticles about 8nm size were synthesized by liquid phase precipitation method. Then the nanoparticles coated with surfactant were dispersed throughout kerosene and inject the solutions into biomaterials. Using strong photon beams in SPring-8 facility, we observed the distribution state and the effect of magnetic field on the behaviour of nanoparticles in biomaterials.

Abstract: Assisted living instruments and medical implants, such as wheelchairs and joint prostheses are usually subjected to biaxial or three-axial stresses instead of uniaxial stress. So, authors already developed a servo biaxial fatigue-testing machine, and clarified about the performance evaluation. Moreover, closed-packed hexagonal lattice metal, such as magnesium and titanium, is frequently used for assisted living instruments or medical implants. In this research, fatigue crack propagation tests of magnesium alloy AZ31B and pure titanium TP340C were conducted under conditions of biaxial and uniaxial loading by using a cruciform specimen in a bi-axial fatigue machine, in order to investigate the effect of non-singular stress cycling on the fatigue crack growth properties ⊿K-da/dN. From these comprehensive experiments, in the magnesium alloy, the re-markable effect was found in the specific biaxial load stress ratio on ⊿K-da/dN relation. When biaxial load stress ratio was 0.5, it turned out that the fatigue crack propagation rate of a magnesium alloy becomes very slow. On the other hand, in the titanium, it was confirmed that there is a little influence of a biaxial load stress ratio on ⊿KⅠ -da/dN relation.