[in Japanese]

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It is not appropriate to use constitutive equations for a blood now in a small artery because of the heterogeneity of the blood. In this paper, a new method to model an erythrocyte by using drag points and springs is proposed as an altanative way to analyze the blood flow. The progression process of this method and advantages are briefly dicribed. Finally, future view of this method is mentioned.

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It has been reported that liquid jet occurs by the irradiation of Ho: YAG laser within tubular structure following formation of laser-induced bubble. We evaluated the characteristics of this laser-induced liquid jet using high speed camera and needle hydrophone. The evaluation by high speed camera indicated that the strength of the jet can be controlled by the laser energy, structure of the nozzle, and stand off distance between optical fiber end and tip of the nozzle. The irradiation of laser-induced liquid jet into the gelatin model and pig liver have resulted in sharp dissection of the tissue, but reserving blood vessels. We consider it has potentials to apply to surgical instrument for cutting tissue, but further examination including evaluation of amount of destruction to surrounding tissue are required.

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Paper reports the irradiation of pulsed Holomium YAG (Ho:YAG) laser beams in water which were transmitted through optical fiber made of quartz and the resulting generation of vapor bubbles in a capillary tube which then induced a jet ejecting from the exit. When the capillary tube was positioned against a gelatin layer which was an artificial model of cerebral thrombi, resulting jet penetrating the gelatin layer exhibited an effective way of revascularization of cerebral thrombosis. Time-resolved optical flow visualization clearly revealed the process of jet formation and resulting penetration. The relationship between laser energy and jet penetration was clarified. In the present study we have optimized the stand-off distance between the tip of fiber and the exit of the capillary tube in order to achieve.

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