Associate for Education and Public Outreach

Yuko Inatomi

  (稲富 裕光)

Profile Information

Affiliation
Professor (Director), Institute of Space and Astronautical Science, Department of Interdisciplinary Space Science, Japan Aerospace Exploration Agency
Professor, School of Physical Sciences, SOKENDAI (The Graduate University for Advanced Studies)
Degree
Doctor of Engineering(Mar, 1992, The University of Tokyo)

Researcher number
50249934
ORCID ID
 https://orcid.org/0000-0002-2845-9636
J-GLOBAL ID
200901018824285220
researchmap Member ID
1000144502

宇宙環境の特性を利用した物質科学研究を通して地球上のみならず宇宙空間における物質の変化を探求しています。具体的には、観測ロケット・国際宇宙ステーションなど宇宙飛翔体による微小重力、遠心機による過重力、強磁場など様々な環境を利用して、凝固・結晶成長の素過程の解明、環境相中の輸送現象の解明と制御、新しい材料プロセスの開発に取り組んでいます。


Papers

 198
  • Haruki Horikoshi, Isamu Orikasa, Minami Kataoka, Yuko Inatomi, Shinsuke Suzuki
    Defect and Diffusion Forum, 439 291-304, Feb 20, 2025  Peer-reviewed
    In this study, we proposed a moved-view analysis, a method for obtaining the Soret coefficient ST by analyzing the interference fringe change during field-of-view movement in the steady state. This analysis was designed to solve the problem that the sign of the concentration gradient could also be reversed if the plot of the concentration distribution was only slightly shifted owing to the narrow field of view. The data obtained from the experiment conducted to measure ST at the International Space Station were analyzed using moved-view analysis. For the moved-view analysis, the linearity of the concentration distribution induced by the Soret effect is larger than that for the method without field-of-view movement, and a more reliable ST can be obtained. The analysis error that sometimes occurred when the laser wavelength switched led to the underestimation of the phase change Δϕ, resulting in generating the data with low linearity. This unreliable data should be removed.
  • Nirmal Kumar Velu, Yasuhiro Hayakawa, Haruhiko Udono, Shunya Sakane, Yuko Inatomi
    ACS Applied Materials and Interfaces, 16(35) 46433-46441, Sep 4, 2024  Peer-reviewedLast author
    Materials with enhanced electron and reduced phonon transport properties are preferred for thermoelectric applications. The defect engineering process can optimize the interrelated electron and phonon transport properties to enhance thermoelectric performance. As the influence of various crystalline defects on the functional properties of materials is diverse, it is crucial to scale, optimize, and understand them experimentally. With this perspective, crystalline defects in InGaSb ternary alloys were engineered and their influence on the thermoelectric properties was studied experimentally. Crystalline defects such as point defects, dislocations, and compositional segregations were induced in In0.95Ga0.05Sb crystals by the addition of excess constituent elements, In, Ga, or Sb. The addition of excess Ga increased point defects, whereas excess Sb reduced dislocation densities. The thermoelectric figure of merit value (ZT) of In0.95Ga0.05Sb+Ga0.02 was recorded to be 0.87 at 573 K, which is the highest among other reported values of III-V semiconductors. The collective interactions of compositional segregations, point defects, and dislocations with electrons and phonons enhanced the ZT in this study.
  • Rachid Ghritli, Yasunori Okano, Yuko Inatomi, Sadik Dost
    Journal of Chemical Engineering of Japan, 56(1) 2222757, Dec 31, 2023  Peer-reviewed
  • Kimura, S., Ishikawa, S., Hayashi, N., Fujita, K., Inatomi, Y., Suzuki, S.
    Frontiers in Microbiology, 14 1253436, Dec, 2023  Peer-reviewed
    <jats:p>Planetary protection is a guiding principle aiming to prevent microbial contamination of the solar system by spacecraft (forward contamination) and extraterrestrial contamination of the Earth (backward contamination). Bioburden reduction on spacecraft, including cruise and landing systems, is required to prevent microbial contamination from Earth during space exploration missions. Several sterilization methods are available; however, selecting appropriate methods is essential to eliminate a broad spectrum of microorganisms without damaging spacecraft components during manufacturing and assembly. Here, we compared the effects of different bioburden reduction techniques, including dry heat, UV light, isopropyl alcohol (IPA), hydrogen peroxide (H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>), vaporized hydrogen peroxide (VHP), and oxygen and argon plasma on microorganisms with different resistance capacities. These microorganisms included <jats:italic>Bacillus atrophaeus</jats:italic> spores and <jats:italic>Aspergillus niger</jats:italic> spores, <jats:italic>Deinococcus radiodurans</jats:italic>, and <jats:italic>Brevundimonas diminuta</jats:italic>, all important microorganisms for considering planetary protection. <jats:italic>Bacillus atrophaeus</jats:italic> spores showed the highest resistance to dry heat but could be reliably sterilized (i.e., under detection limit) through extended time or increased temperature. <jats:italic>Aspergillus niger</jats:italic> spores and <jats:italic>D. radiodurans</jats:italic> were highly resistant to UV light. Seventy percent of IPA and 7.5% of H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> treatments effectively sterilized <jats:italic>D. radiodurans</jats:italic> and <jats:italic>B. diminuta</jats:italic> but showed no immediate bactericidal effect against <jats:italic>B. atrophaeus</jats:italic> spores. IPA immediately sterilized <jats:italic>A. niger</jats:italic> spores, but H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> did not. During VHP treatment under reduced pressure, viable <jats:italic>B. atrophaeus</jats:italic> spores and <jats:italic>A. niger</jats:italic> spores were quickly reduced by approximately two log orders. Oxygen plasma sterilized <jats:italic>D. radiodurans</jats:italic> but did not eliminate <jats:italic>B. atrophaeus</jats:italic> spores. In contrast, argon plasma sterilized <jats:italic>B. atrophaeus</jats:italic> but not <jats:italic>D. radiodurans</jats:italic>. Therefore, dry heat could be used for heat-resistant component bioburden reduction, and VHP or plasma for non-heat-resistant components in bulk bioburden reduction. Furthermore, IPA, H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>, or UV could be used for additional surface bioburden reduction during assembly and testing. The systemic comparison of sterilization efficiencies under identical experimental conditions in this study provides basic criteria for determining which sterilization techniques should be selected during bioburden reduction for forward planetary protection.</jats:p>
  • Nirmal Kumar Velu, Yasuhiro Hayakawa, Haruhiko Udono, Yuko Inatomi
    Journal of Materials Science: Materials in Electronics, 34(19) 1480, Jul, 2023  Peer-reviewedLast author
    Thermoelectric materials with optimum carrier concentration of the order of 1019–1020/cm3 are required to obtain a high figure of merit (ZT) value. As undoped In0.8Ga0.2Sb has a lower carrier concentration (~1016/cm3), Te impurity was doped between low (1 × 1018/cm3) and high level (1 x 1021/cm3) to understand the effects of doping on its thermoelectric properties. The undoped and Te-doped In0.8Ga0.2Sb crystals retained cubic zinc blende crystal structure irrespective of heavy doping of Te element. In addition to the optical phonon vibrational modes, acoustic phonon modes were also present when the doping concentration exceeded 1 × 1018/cm3. The carrier concentration in Te-doped In0.8Ga0.2Sb crystals were varied in the range 1018–1020/cm3. Te-doped In0.8Ga0.2Sb with concentration 1 × 1018/cm3 was recorded a higher power factor because of its lower resistivity and higher mobility than other crystals. The ZT of Te-doped In0.8Ga0.2Sb (1 × 1018/cm3) was higher than other samples at 300–450 K. This study revealed that the optimum Te dopant concentration to enhance the ZT value of InxGa1−xSb is 1 x 1018/cm3 for optimizing its properties toward mid-temperature thermoelectric applications.

Misc.

 281

Books and Other Publications

 12

Presentations

 555

Teaching Experience

 4

Research Projects

 36

Industrial Property Rights

 3

Academic Activities

 5

Social Activities

 15