Our group is currently developing a pneumatic ventricular assist device (PVAD). In order to select the optimal bileaflet valve for our PVAD, in the current study we investigated the evolution of the flow field in a detailed time domain of three kinds of commercial bileaflet valves in our PVAD by means of the 2D particle image velocimetry method. To carry out flow visualization inside the blood pump and near the valve, we designed a model pump with the same configuration as our PVAD. Three kinds of bileaflet valves, the ATS valve, St. Jude valve and Sorin valve were mounted at the aortic position of the model pump and the flow was visualized by the PIV method. The maximum flow-velocity and Reynolds shear stress of the Sorin valve were less than those of the other two bileaflet valves. The Sorin valve has low Reynolds shear stress, and is considered the best valve for our PVAD among the three valves tested.

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This study examined effects of the static magnetic field given by the magnetic assemblies (Hicorex Slim 4013, Hitachi Metals, Japan) on osteogenesis in vivo. They were implanted to 2 by 2 in both tibiae of male Japanese rabbits for 1, 2, 4, 8 and 12 weeks (n=6), and their osteogenesis was histologically observed. Osteoblast-like SaOS-2 cells suspended on the magnetic assemblies were regularly cultured. The static magnetic field seemed to stimulate and accelerate the osteogenesis within the early stage of its exposure. In addition, it also significantly (p<0.05) increased the cell proliferation and extracellular matrix (ECM) production of SaOS-2 cells both in 4 and 8 days' culture, and in fact, it accelerated or maintained the osteogenic differentiation of SaOS-2 osteoblasts.

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In this study, we examined mechanical and chemical properties of the consolidated Ti-based metallic glass. Ti-based metallic glasses exhibit high compressive strength, good corrosion resistance in simulated body fluids as well as does not contain Ni, Al and V elements which are well known to be toxic. In addition, experimental results revealed high consolidation ability within flow viscosity region which has compatible thermal stability with those of Zr- or Fe-based metallic glasses with wide supercooled liquid region. And it was confirmed that SPS (spark plasma sintering) technique contributed forming process for Ti-based metallic glass powder and effectively created volume forming ability without any crystallization.

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[in Japanese]

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