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649 results on '"Matsukawa, Mami"'

1. Brillouin Scattering of B2O3-Alkali Oxide Glasses

Author

Shirakawa, Yoshiyuki, Sogo, Toshiki, Yamada, Jun-ichi, Iida, Takamichi, Ohtori, Norikazu, Matsukawa, Mami, and Umesaki, Norimasa

Subjects
Technology, Chemical technology, TP1-1185, Chemicals: Manufacture, use, etc., TP200-248
Published
1999
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3. Piezoelectric and Opto-Acoustic Material Properties of Bone

Author

Hosokawa, Atsushi, Matsukawa, Mami, Crusio, Wim E., Series Editor, Dong, Haidong, Series Editor, Radeke, Heinfried H., Series Editor, Rezaei, Nima, Series Editor, Steinlein, Ortrud, Series Editor, Xiao, Junjie, Series Editor, Laugier, Pascal, editor, and Grimal, Quentin, editor

Published
2022
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6. Fluid friction and wall viscosity of the 1D blood flow model

Author

Wang, Xiao-Fei, Nishi, Shohei, Matsukawa, Mami, Ghigo, Arthur, Lagrée, Pierre-Yves, and Fullana, Jose-Maria

Subjects
Physics - Fluid Dynamics, Condensed Matter - Soft Condensed Matter
Abstract

We study the behavior of the pulse waves of water into a flexible tube for application to blood flow simulations. In pulse waves both fluid friction and wall viscosity are damping factors, and difficult to evaluate separately. In this paper, the coefficients of fluid friction and wall viscosity are estimated by fitting a nonlinear 1D flow model to experimental data. In the experimental setup, a distensible tube is connected to a piston pump at one end and closed at another end. The pressure and wall displacements are measured simultaneously. A good agreement between model predictions and experiments was achieved. For amplitude decrease, the effect of wall viscosity on the pulse wave has been shown as important as that of fluid viscosity., Comment: Submitted to Journal of Biomechanics, 2015

Published
2015

11. Optical evaluation of a double-layered ultrasound liquid crystal lens.

Author

Onaka, Jessica, Koyama, Daisuke, Kuroda, Yuma, Emoto, Akira, and Matsukawa, Mami

Subjects
LIQUID crystals, NEMATIC liquid crystals, FOCAL length, ELASTIC constants, ULTRASONIC imaging
Abstract

A method to improve the performance of an ultrasound liquid crystal lens is proposed. A double-layer-based lens model tailored based on the liquid crystal's physical properties, e.g., its dielectric anisotropy and elastic constants, is presented as an alternative method to improve the lens's optical performance while forming weak anchoring surfaces for nematic liquid crystals, thus promoting easier reorientation of the liquid crystal molecules. The lens configuration was simulated by finite-element analysis using Ansys software. The lens's physical and optical characteristics were evaluated via comparison using two different liquid crystal materials: 5CB and RDP-85475. The birefringence distribution within the liquid crystal layer was investigated under ultrasound excitation, and the molecular angles of inclination were estimated. A higher birefringence distribution, greater molecular inclination, and a longer focal length were obtained for the double-layered liquid crystal lens using the 5CB material. [ABSTRACT FROM AUTHOR]

Published
2022
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34. Simulation of ultrasonically induced electrical potentials in bone.

Author

Suzuyama, Hidehisa, Tsubata, Taisei, Kitajima, Shouta, Maehara, Keigo, Hosokawa, Atsushi, Tsuchiya, Takao, and Matsukawa, Mami

Subjects
ELECTRIC fields, THEORY of wave motion, SHEAR waves, PIEZOELECTRICITY, BONE fractures, FRACTURE healing, BONE mechanics
Abstract

Low-intensity pulsed ultrasound treatment is known to shorten the healing period of bone fractures by 30%–40%, but the initial mechanism of the healing process remains unknown. One possible mechanism is related to the piezoelectricity of bone. However, the complex geometry of bones results in inherent challenges to evaluating electric fields induced therein. Therefore, in this study, we investigate the piezoelectric responses of bones by using simulations to study the wave propagation and induced potentials in bone, according to the piezoelectric finite-difference time-domain (PE-FDTD) method. First, we verify the suitability of the PE-FDTD method by comparing the simulated electric field results with the experimental data obtained by an ultrasound receiver using bone as the piezoelectric element. Next, ultrasound irradiation into a real bone model (the radius of a 66-year-old woman) is simulated at different incident angles. At normal incidence and off-axis incidence (45°), the maximum electric field strength was 4.3 and 5.6 mV/cm, respectively. We also present evidence of significant shear wave contribution to the induced potential. The results of this study confirm the existence of ultrasonically induced potentials in heterogenous bones with complex shapes, equal in magnitude to potentials generated in electrically stimulated bone healing. [ABSTRACT FROM AUTHOR]

Published
2023
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