Y. Sakurai

Japan Synchrotron Radiation Research Institute (JASRI), Tatsuno, Hyōgo, Japan

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Publications (319)730.58 Total impact

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    ABSTRACT: We present an incisive spectroscopic technique for directly probing redox orbitals based on bulk electron momentum density measurements via high-resolution x-ray Compton scattering. Application of our method to spinel LixMn2O4, a lithium ion battery cathode material, is discussed. The orbital involved in the lithium insertion and extraction process is shown to mainly be the oxygen 2p orbital. Moreover, the manganese 3d states are shown to experience spatial delocalization involving 0.16 electrons per Mn site during the battery operation. Our analysis provides a clear understanding of the fundamental redox process involved in the working of a lithium ion battery.
    Physical Review Letters 03/2015; 114(8). DOI:10.1103/PhysRevLett.114.087401 · 7.73 Impact Factor
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    ABSTRACT: Spin-polarized Compton profiles of TbCo2have been measured to elucidate the interesting behavior of spin and orbital moments at different temperatures. The magnetic Compton profiles (MCPs) have been analyzed in terms of site specific spin moments due to Tb-4f electrons, Co and itinerant electrons. The temperature dependence of the orbital moment has been deduced using Compton and magnetometry data ranging between 6 and 300 K. The present data exhibit a decrease in the ratio of orbital to spin moments from 43.9% to 35.0% (while going from 6 to 300 K). First-principles calculations within DFT + U scheme have also been performed to confirm the spin-, orbital- and site specific-magnetic moments in TbCo2. An antiparallel exchange coupling between the Tb-4f and Co spin moments is found. The orbital moment is found to have a parallel coupling with the Tb spin moment, as evident from the experimental MCPs. From first-principles data it is seen that the orbital moments of Tb and Co sites are antiparallel to each other, as in the case of their spin magnetic moments. The present experimental study also shows an existence of an itinerant moment which is coupled ferromagnetically with the Tb-4f spin moment
    Journal of Alloys and Compounds 02/2015; 633:430-434. DOI:10.1016/j.jallcom.2015.02.029 · 2.73 Impact Factor
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    ABSTRACT: n this study, the magnetic properties of FeAl alloys with different grain sizes produced by high-pressure torsion were probed by means of magnetic Compton scattering. The measurements were performed at 300 and 10 K. Magnetic Compton profiles of nanocrystalline (35 nm) and ultrafine-grained (160 nm) FeAl alloys were analyzed in terms of the integral area, the width, and the distinctive dip intensity at low momenta. The changes in total magnetic moment and the strength of spin-polarization of itinerant electrons are assumed to be caused by vacancies induced during the preparation of the samples. Despite local disordering due to interfacial regions and deviations in perfect stoichiometry for B2 structure, the effect of vacancies is considered as the major magnetic state contributor.
    Journal of Physics Condensed Matter 02/2015; 27(7). DOI:10.1088/0953-8984/27/7/075304 · 2.22 Impact Factor
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    ABSTRACT: The first BNCT antitumor effects of BNNTs toward B16 melanoma cells were demonstrated. The use of DSPE-PEG2000 was effective for preparation of the BNNT-suspended aqueous solution. BNNT-DSPE-PEG2000 accumulated in B16 melanoma cells approximately three times higher than BSH and the higher BNCT antitumor effect was observed in the cells treated with BNNT-DSPE-PEG2000 compared to those treated with BSH, indicating that BNNT-DSPE-PEG2000 would be a possible candidate as a boron delivery vehicle for BNCT. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Bioorganic & Medicinal Chemistry Letters 12/2014; 25(2). DOI:10.1016/j.bmcl.2014.12.005 · 2.33 Impact Factor
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    ABSTRACT: Carboranyl-containing chlorins have emerged as promising dual sensitizers for use in both photodynamic therapy (PDT) and boron neutron capture therapy (BNCT), by virtue of their known tumor affinity, low cytotoxicity in dark conditions, and their strong absorptions in the red region of the optical spectrum. Tetrakis(p-carboranylthio-tetrafluorophenyl)chlorin (TPFC) is a new synthetic carboranyl-containing chlorin of high boron content (24% by weight). To evaluate TPFC's applicability as sensitizer for both PDT and BNCT, we performed an in vitro and in vivo study using F98 rat glioma cells and F98 rat glioma-bearing brain tumor models. For the in vivo BNCT study, we used boronophenylalanine (BPA), which is currently used in clinical BNCT studies, via intravenous administration (i.v.) and/or used TPFC via convection-enhanced delivery (CED), a method for local drug infusion directly into the brain. In the in vitro PDT study, the cell surviving fraction following laser irradiation (9 J/cm2) was 0.035 whereas in the in vitro BNCT study, the cell surviving fraction following neutron irradiation (thermal neutron = 1.73 × 1012 n/cm2) was 0.04. In the in vivo BNCT study, the median survival time following concomitant administration of BPA (i.v.) and TPFC (CED) was 42 days (95% confidence interval; 37–43 days). © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci
    Journal of Pharmaceutical Sciences 12/2014; 104(3). DOI:10.1002/jps.24317 · 3.01 Impact Factor
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    ABSTRACT: We treated a 54-year-old Japanese female with a recurrent radiation-induced osteosarcoma arising from left occipital skull, by reactor-based boron neutron capture therapy (BNCT). Her tumor grew rapidly with subcutaneous and epidural extension. She eventually could not walk because of cerebellar ataxia. The tumor was inoperable and radioresistant. BNCT showed a marked initial therapeutic effect: the subcutaneous/epidural tumor reduced without radiation damage of the scalp except hair loss and the patient could walk again only 3 weeks after BNCT. BNCT seems to be a safe and very effective modality in the management of radiation-induced osteosarcomas that are not eligible for operation and other treatment modalities.
    Radiation Oncology 11/2014; 9(1):237. DOI:10.1186/s13014-014-0237-z · 2.36 Impact Factor
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    ABSTRACT: In this study, we investigated γH2AX foci as markers of DSBs in normal brain and brain tumor tissue in mouse after BNCT.
    Reports of Practical Oncology and Radiotherapy 10/2014; DOI:10.1016/j.rpor.2014.10.005
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    ABSTRACT: The aim of the present study was to evaluate the effect of bevacizumab on local tumor response and lung metastatic potential during boron neutron capture therapy (BNCT) and in particular, the response of intratumor quiescent (Q) cells. B16-BL6 melanoma tumor-bearing C57BL/6 mice were continuously administered bromodeoxyuridine (BrdU) to label all proliferating (P) tumor cells. The tumors were irradiated with thermal neutron beams following the administration of a (10)B-carrier [L-para-boronophenylalanine-(10)B (BPA) or sodium mercaptoundecahydrododecaborate-(10)B (BSH)], with or without the administration of bevacizumab. This was further combined with an acute hypoxia-releasing agent (nicotinamide) or mild temperature hyperthermia (MTH, 40°C for 60 min). Immediately following the irradiation, cells from certain tumors were isolated and incubated with a cytokinesis blocker. The responses of the Q cells and the total (P+Q) cell populations were assessed based on the frequency of micronuclei using immunofluorescence staining for BrdU. In other tumor-bearing mice, 17 days following irradiation, lung metastases were enumerated. Three days following bevacizumab administration, the sensitivity of the total tumor cell population following BPA-BNCT had increased more than that following BSH-BNCT. The combination with MTH, but not with nicotinamide, further enhanced total tumor cell population sensitivity. Regardless of the presence of a (10)B-carrier, MTH enhanced the sensitivity of the Q cell population. Regardless of irradiation, the administration of bevacizumab, as well as nicotinamide treatment, demonstrated certain potential in reducing the number of lung metastases especially in BPA-BNCT compared with BSH-BNCT. Thus, the current study revealed that BNCT combined with bevacizumab has the potential to sensitize total tumor cells and cause a reduction in the number of lung metastases to a similar level as nicotinamide.
    Experimental and therapeutic medicine 07/2014; 8(1):291-301. DOI:10.3892/etm.2014.1704 · 0.94 Impact Factor
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    ABSTRACT: A 63-year-old man with multiple HCC in his left liver lobe was enrolled as the first patient in a pilot study of boron neutron capture therapy (BNCT) involving the selective intra-arterial infusion of a 10BSH-containing water-in-oil-in-water emulsion (10BSH-WOW). The size of the tumorous region remained stable during the 3 months after the BNCT. No adverse effects of the BNCT were observed. The present results show that 10BSH-WOW can be used as novel intra-arterial boron carriers during BNCT for HCC.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 06/2014; 88. DOI:10.1016/j.apradiso.2014.01.014 · 1.06 Impact Factor
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    ABSTRACT: Radiation doses during boron neutron capture therapy for body-trunk tumors were estimated for various internal organs, using data from patients treated at Kyoto University Research Reactor Institute. Dose-volume histograms were constructed for tissues of the lung, liver, kidney, pancreas, and bowel. For pleural mesothelioma, the target total dose to the normal lung tissues on the diseased side is 5 Gy-Eq in average for the whole lung. It was confirmed that the dose to the liver should be carefully considered in cases of right lung disease.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 06/2014; 88. DOI:10.1016/j.apradiso.2014.03.005 · 1.06 Impact Factor
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    ABSTRACT: Temperature dependent spin momentum densities of NiFe2−xRExO4 (x=0, 0.05; RE=Dy, Gd) ferrites have been measured using a magnetic Compton spectrometer available at SPring-8, Japan. The experimental profiles of NiFe2O4 (NFO) with doping of Dy and Gd show almost similar spin moment as of undoped NFO. The contribution of different constituents in the formation of total spin moment is also deduced from the analysis of Compton line shape. It is seen that 5% doping of Dy3+ or Gd3+ ions at Fe3+ sites leads to a redistribution of spin moment at Fe3+ and RE3+ sites. The magnetic Compton data when compared with the magnetization data (using a vibrating sample magnetometer) show almost a constant orbital moment (0.21±0.03 µB/f.u.) in the doped and undoped NFO.
    Journal of Magnetism and Magnetic Materials 06/2014; 360:113–117. DOI:10.1016/j.jmmm.2014.02.045 · 2.00 Impact Factor
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    ABSTRACT: It is important to measure the microdistribution of 10B in a cell to predict the cell-killing effect of new boron compounds in the field of boron neutron capture therapy. Alpha autoradiography has generally been used to detect the microdistribution of 10B in a cell. Although it has been performed using a reactor-based neutron source, the realization of an accelerator-based thermal neutron irradiation field is anticipated because of its easy installation at any location and stable operation. Therefore, we propose a method using a cyclotron-based epithermal neutron source in combination with a water phantom to produce a thermal neutron irradiation field for alpha autoradiography. This system can supply a uniform thermal neutron field with an intensity of 1.7×109 (cm−2 s−1) and an area of 40 mm in diameter. In this presentation, we give an overview of our proposed system and describe a demonstration test using a mouse liver sample injected with 500 mg/kg of boronophenyl-alanine.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 06/2014; 88. DOI:10.1016/j.apradiso.2014.01.011 · 1.06 Impact Factor
  • Kenichi Tanaka, Yoshinori Sakurai, Satoru Endo, Jun Takada
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    ABSTRACT: In order to measure the spatial distributions of neutrons and gamma rays separately using the imaging plate, the requirement for the converter to enhance specific component was investigated with the PHITS code. Consequently, enhancing fast neutrons using recoil protons from epoxy resin was not effective due to high sensitivity of the imaging plate to gamma rays. However, the converter of epoxy resin doped with 10B was found potential for thermal and epithermal neutrons, and graphite for gamma rays.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 06/2014; 88. DOI:10.1016/j.apradiso.2013.12.038 · 1.06 Impact Factor
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    ABSTRACT: We present the spin momentum density of Ga doped CoFe2O4 at 100 K using magnetic Compton scattering. The measurement has been performed using circularly polarized synchrotron radiations of 182.65 keV at SPring8, Japan. The experimental profile is decomposed into its constituent profile to determine the spin moment at individual sites. Co atom has the maximum contribution (about 58%) in the total spin moment of the doped CoFe2O4.
    03/2014; 1591(1). DOI:10.1063/1.4873088
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    ABSTRACT: New anti-cancer therapy with boron neutron capture therapy (BNCT) is based on the nuclear reaction of boron-10 with neutron irradiation. The median survival of BNCT patients with glioblastoma was almost twice as long as those receiving standard therapy in a Japanese BNCT clinical trial. In this clinical trial, two boron compounds, BPA (boronophenylalanine) and BSH (sodium borocaptate), were used for BNCT. BPA is taken up into cells through amino acid transporters that are expressed highly in almost all malignant cells, but BSH cannot pass through the cell membrane and remains outside the cell. We simulated the energy transfer against the nucleus at different locations of boron from outside the cell to the nuclear region with neutron irradiation and concluded that there was a marked difference between inside and outside the cell in boron localization. To overcome this disadvantage of BSH in BNCT, we used a cell-penetrating peptide system for transduction of BSH. CPP (cell-membrane penetrating peptide) is very common peptide domains that transduce many physiologically active substances into cells in vitro and in vivo. BSH-fused CPPs can penetrate the cell membrane and localize inside a cell. To increase the boron ratio in one BSH-peptide molecule, 8BSH fused to 11R with a dendritic lysine structure was synthesized and administrated to malignant glioma cells and a brain tumor mouse model. 8BSH-11R localized at the cell nucleus and showed a very high boron value in ICP results. With neutron irradiation, the 8BSH-11R administrated group showed a significant cancer killing effect compared to the 100 times higher concentration of BSH-administrated group. We concluded that BSH-fused CPPs were one of the most improved and potential boron compounds in the next-stage BNCT trial and 8BSH-11R may be applied in the clinical setting.
    Biomaterials 01/2014; 35(10). DOI:10.1016/j.biomaterials.2013.12.055 · 8.31 Impact Factor
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    ABSTRACT: To examine the effect of the type and the concentration of neutron capture agents on the values of compound biological effectiveness (CBE) in boron neutron capture therapy. After the subcutaneous administration of a (10) B-carrier, boronophenylalanine- (10) B (BPA) or sodium mercaptododecaborate- (10) B (BSH), at 3 separate concentrations, the (10) B concentrations in tumors were measured by γ-ray spectrometry. SCC VII tumor-bearing C3H/He mice received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all intratumor proliferating (P) cells, then treated with BPA or BSH. Immediately after reactor neutron beam irradiation, during which intratumor (10) B concentrations were kept at levels similar to each other, cells from some tumors were isolated and incubated with a cytokinesis blocker. The responses of BrdU-unlabeled quiescent (Q) and total (= P + Q) tumor cells were assessed based on the frequencies of micronucleation using immunofluorescence staining for BrdU. The CBE values were higher in Q cells and in the use of BPA than total cells and BSH, respectively. In addition, the higher the administered concentrations were, the smaller the CBE values became, with a clearer tendency in the use of BPA than BSH. The values for neutron capture agents that deliver into solid tumors more dependently on uptake capacity of tumor cells became more changeable. Tumor characteristics, such as micro-environmental heterogeneity, stochastic genetic or epigenetic changes, or hierarchical organization of tumor cells, are thought to partially influence on the value of CBE, meaning that the CBE value itself may be one of the indices showing the degree of tumor heterogeneity.
    SpringerPlus 01/2014; 3(1):128. DOI:10.1186/2193-1801-3-128
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    ABSTRACT: As a nanoparticulate device for controlled delivery of Gd in NCT, the authors have developed gadolinium-loaded chitosan nanoparticles (Gd-nanoCPs). In the present study, influence of micrometric properties such as particle size, particle-surface charge and Gd content of Gd-nanoCPs on tumor-killing effect by Gd-NCT was investigated with Gd-nanoCPs. Two types of Gd-nanoCPs with different mean particle size, zeta potential and Gd-content (Gd-nanoCP-400; 391nm, 28mV, 9wt% and Gd-nanoCP-200; 214nm, 19mV, 24wt%) could be prepared by using chitosans with different molecular weights. Gd-nanoCPs incorporating 1.2mg of natural Gd were injected intratumorally once or twice to mice subcutaneously-bearing B16F10 melanoma. Eight hours after the last administration, thermal neutron was irradiated to tumor region of the mice. Remarkable tumor-growth was observed in both hot and cold control groups. In contrast, Gd-NCT groups showed significant tumor-growth suppression effect, though their efficacy was found to depend on the micrometric properties of Gd-nanoCPs. In particular, the Gd-nanoCP-200 exhibited stronger tumor-killing effect than the Gd-nanoCP-400 at the same Gd dose and it was still similar to Gd-nanoCP-400 in tumor-growth suppressing effect even at the half of Gd dose of Gd-nanoCP-400. This significance in tumor-killing effect would be ascribed from a higher Gd retention in the tumor tissue and an improved distribution of Gd with intratumorally administered Gd-nanoCP-200. Indeed, the Gd concentration in tumor tissue at the time corresponding to the onset of thermal neutron irradiation was determined to be significantly higher in Gd-nanoCP-200, compared with Gd-nanoCP-400. These results demonstrated that appropriate modification of Gd-nanoCPs in micrometric properties would be an effective way to improve the retention of Gd in the tumor tissue after intratumoral injection, leading to the enhanced tumor-killing effect in Gd-NCT.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 12/2013; 88. DOI:10.1016/j.apradiso.2013.12.018 · 1.06 Impact Factor
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    ABSTRACT: Clear cell sarcoma (CCS) is a rare malignant tumor with a poor prognosis. In our previous study, the tumor disappeared under boron neutron capture therapy (BNCT) on subcutaneously-transplanted CCS-bearing animals. In the present study, the tumor disappeared under this therapy on model mice intramuscularly implanted with three different human CCS cells. BNCT led to the suppression of tumor-growth in each of the different model mice, suggesting its potentiality as an alternative to, or integrative option for, the treatment of CCS.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 12/2013; 88. DOI:10.1016/j.apradiso.2013.12.007 · 1.06 Impact Factor
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    ABSTRACT: Boron neutron capture therapy (BNCT) is a selective radiotherapy that is dependent on the accumulation of 10B compound in tumors. Low-intensity ultrasound produces a transient pore on cell membranes, sonoporation, which enables extracellular materials to enter cells. The effect of sonoporation on BNCT was examined in oral squamous cell carcinoma (SCC) xenografts in nude mice.Materials and methods: Tumor-bearing mice were administrated boronophenylalanine (BPA) or boronocaptate sodium (BSH) intraperitoneally. Two hours later, tumors were subjected to sonoporation using microbubbles followed by neutron irradiation. The 10B concentration was higher in tumors treated with sonoporation than in untreated tumors, although the difference was not significant in BPA. When tumors in mice that received BPA intraperitoneally were treated with sonoporation followed by exposure to thermal neutrons, tumor volume was markedly reduced and the survival rate was prolonged. Such enhancements by sonoporation were not observed in mice treated with BSH-mediated BNCT. These results indicate that sonoporation enhances the efficiency of BPA-mediated BNCT for oral SCC. Sonoporation may modulate the microlocalization of BPA and BSH in tumors and increase their intracellular levels.
    Radiation Oncology 12/2013; 8(1):280. DOI:10.1186/1748-717X-8-280 · 2.36 Impact Factor
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    ABSTRACT: Boron neutron capture therapy (BNCT) can be utilized to selectively kill cancer cells using a boron compound that accumulates only in cancer cells and not in normal cells. Tumor-bearing animals treated by BNCT are routinely used to evaluate long-term antitumor effects of new boron compounds. Alpha-autoradiography is one of the methods employed in the evaluation of antitumor effects. However, a standard alpha-autoradiography cannot detect the microdistribution of (10)B because of the difficulty associated with the superposition of a tissue sample image and etched pits on a track detector with the etching process. In order to observe the microdistribution of (10)B, some special methods of alpha-autoradiography have been developed that make use of a special track detector, or the atomic force microscope combined with X-ray and UV light irradiation. In contrast, we propose, herein, a simple and rapid method of precisely identifying the position of (10)B using the imaging process and the shape of etched pits, such as their circularity, without the need to use special track detectors or a microscope. A brief description of this method and its verification test are presented in this article. We have established a method of detecting the microdistribution of (10)B with submicron deviation between the position of etched pits and the position of reaction in a tissue sample, for a given circularity of etched pits.
    Journal of Radiation Research 10/2013; DOI:10.1093/jrr/rrt110 · 1.69 Impact Factor

Publication Stats

2k Citations
730.58 Total Impact Points

Institutions

  • 2000–2015
    • Japan Synchrotron Radiation Research Institute (JASRI)
      Tatsuno, Hyōgo, Japan
  • 1994–2014
    • Kyoto University
      • Research Reactor Institute
      Kioto, Kyōto, Japan
  • 2006–2011
    • The University of Tokushima
      • • Department of Life Systems
      • • Faculty of Engineering
      Tokushima-shi, Tokushima-ken, Japan
  • 2010
    • Osaka City University
      Ōsaka, Ōsaka, Japan
  • 2009
    • University of Bristol
      • School of Chemistry
      Bristol, England, United Kingdom
  • 2008
    • Japan Atomic Energy Agency
      Muramatsu, Niigata, Japan
  • 2007–2008
    • Sapporo Medical University
      Sapporo, Hokkaidō, Japan
    • Shinshu University
      • Division of Information Engineering
      Shonai, Nagano, Japan
  • 2003–2008
    • Osaka Medical College
      • Department of Neurosurgery
      Takatuki, Ōsaka, Japan
    • National Cancer Center Korea
      Kōyō, Gyeonggi-do, South Korea
  • 2004
    • University of California, Berkeley
      Berkeley, California, United States
    • Kinki University
      Ōsaka, Ōsaka, Japan
    • Himeji Institute of Technology
      • Faculty of Science
      Himezi, Hyōgo, Japan
  • 2002
    • Hiroshima University
      • Research Institute for Radiation Biology and Medicine (RIRBM)
      Hiroshima-shi, Hiroshima-ken, Japan
  • 1983–2000
    • Tokyo Gakugei University
      • Department of Natural and Environmental Science
      Koganei, Tōkyō, Japan
  • 1995
    • RIKEN
      Вако, Saitama, Japan
  • 1991
    • Gunma University
      • Faculty of Engineering
      Maebashi, Gunma, Japan
  • 1988–1990
    • The University of Tokyo
      • Institute of Industrial Science
      Tokyo, Tokyo-to, Japan