山田　努 (ヤマダ　ツトム)

YAMADA Tsutomu

所属組織

大学院工学研究院 知的構造の創生部門

職名

助手

研究分野・キーワード

磁性薄膜、磁気ワイヤー


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  • 磁気応用

    研究期間：  - 

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  • Enhanced specific loss power from Resovist (R) achieved by aligning magnetic easy axes of nanoparticles for hyperthermia

    Shi Guannan, Takeda Ryoji, Trisnanto Suko Bagus, Yamada Tsutomu, Ota Satoshi, Takemura Yasushi

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   473   148 - 154   2019年03月

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    Web of Science DOI

  • High intrinsic loss power of multicore magnetic nanoparticles with blood-pooling property for hyperthermia

    Nishimoto Kizuku, Ota Satoshi, Shi Guannan, Takeda Ryoji, Trisnanto Suko Bagus, Yamada Tsutomu, Takemura Yasushi

    AIP ADVANCES   9 ( 3 )   2019年03月

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    Web of Science DOI

  • Power Supply for Medical Implants by Wiegand Pulse Generated from Magnetic Wire

    K. Takahashi, A. Takebuchi, T. Yamada, Y. Takemura

    Journal of the Magnetics Society of Japan ( The Magnetics Society of Japan )  42 ( 2 ) 49 - 54   2018年03月  [査読有り]

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    DOI

  • Evaluation of Dispersibility in Liquid and AC Magnetization Properties of Polyion Complex-Coupled Magnetic Nanoparticles

    Shi Guannan, Trisnanto Suko Bagus, Nakai Keita, Yusa Shin-ichi, Yamada Tsutomu, Ota Satoshi, Takemura Yasushi

    日本応用磁気学会誌 ( 公益社団法人 日本磁気学会 )  42 ( 2 ) 41 - 48   2018年

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    　概要を見る

    <p>  Medical applications such as those using magnetic nanoparticles (MNPs) for hyperthermia and magnetic particle imaging (MPI) require suitably designed particles with distinct characteristics. However, it is challenging to develop such particles with a high degree of biocompatibility. In this study, a cationic diblock copolymer (PMPC<sub>100</sub>-<i>b</i>-MMAPTAC<sub>100</sub>: P<sub>100</sub>M<sub>100</sub>) composed of poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) and poly(3-(methacryloylamino)propyl trimethylammonium chloride) (PMAPTAC) was synthesized via a controlled radical polymerization technique to obtain particles with high biocompatibility and antithrombogenicity. Magnetic polyion complex (PIC) aggregate (M-300/P<sub>100</sub>M<sub>100</sub>) is an aggregate of magnetic Fe<sub>3</sub>O<sub>4</sub> nanoparticles (M-300), in which their anionic surface is electrostatically coated with cationic PMPC<sub>100</sub>-<i>b</i>-MMAPTAC<sub>100</sub> (P<sub>100</sub>M<sub>100</sub>). We investigated the stability of the magnetic PIC aggregate in an ionic solution by evaluating the relationship between the particle diameter and salt concentration. We then estimated the intrinsic loss power (ILP) from the areas of the alternating current (AC) hysteresis loops and measured the AC magnetization of the magnetic PIC aggregate. The peak frequencies from the Brownian relaxation of M-300 and M-300/P<sub>100</sub>M<sub>100</sub> were 9 kHz and 245 Hz, respectively. When the third harmonic was evaluated for use in MPI, the signal intensity was found to be comparable to that of M-300 in a fixed state.</p>

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  • Dynamic Hysteresis Measurement of Magnetic Nanoparticles with Aligned Easy Axes

    Takeda Ryoji, Ota Satoshi, Yamada Tsutomu, Takemura Yasushi

    日本応用磁気学会誌 ( 公益社団法人 日本磁気学会 )  42 ( 2 ) 55 - 61   2018年

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    　概要を見る

    <p>  Magnetic particle imaging (MPI) is a novel diagnostic imaging technique based on the use of magnetic nanoparticles (MNPs). Investigating the magnetic properties of magnetic nanoparticles is important for achieving a high spatial and temporal resolution in MPI. In this study, γ-Fe<sub>2</sub>O<sub>3</sub> nanoparticles (core diameter: <i>d</i><sub>c</sub> = 4 nm), Fe<sub>3</sub>O<sub>4</sub> nanoparticles (<i>d</i><sub>c</sub> = 20–30 nm), and Resovist<sup>®</sup> were immobilized in a DC magnetic field with their easy axes aligned. DC and AC magnetization curves were measured for the prepared MNPs. The measurements were performed by applying fields parallel and perpendicular to the easy axis and evaluating the magnetic properties of the MNPs for the easy and hard axes. The direction of magnetic moments under the AC magnetic field applied to the direction of the easy axis or hard axis was evaluated by using both experimental results and numeric simulation using the Landau–Lifshitz–Gilbert equation to reveal magnetic relaxation property at wide frequency range and the effect of core size distribution of oriented MNPs. The effect of anisotropy in superparamagnetic nanoparticles, the relaxation property depending on the anisotropy energy barrier, and the fast magnetization process of Néel relaxation were successfully observed.</p>

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