Updated on 2021/04/02

写真a

 
KUMAGAI, Jun
 
Organization
Institute of Materials and Systems for Sustainability Division of Materials Research Associate professor
Title
Associate professor
Contact information
メールアドレス

Degree 1

  1. Ph. D. ( 1995.6   Hokkaido University ) 

Research Interests 8

  1. Delayed Radiation Effects, Radiation induced Cancer, Slow-Releasing Long-Lived Radicals, Resistant Materials for ionizing and neutron radiation, Nano-resist materials for next generation with EUV, Solid Hydrogen, H6+ ions, ESR, ENDOR, ESEEM

  2. Delayed Radiation Effects

  3. Solid Hydrogen

  4. Radiation induced Cancer

  5. H6+ ions

  6. ESR

  7. ENDOR

  8. ESEEM

Research Areas 6

  1. Others / Others  / Radiation/Chemical Substance Influence Science

  2. Others / Others  / Physical Chemistry

  3. Others / Others  / Industrial Physical Chemistry

  4. Others / Others  / Atomic/Molecular/Quantum Electronics/Plasma

  5. Environmental Science/Agriculture Science / Radiation influence

  6. Energy Engineering / Nuclear engineering

▼display all

Current Research Project and SDGs 4

  1. Effect of slow-releasing long-lived radicals produced in recipient cells on bystander biological damage by irradiated medium transfer.

  2. 極低温ESR法による光触媒素反応研究

  3. 低レベル放射性廃棄物セメント固化処分における水素発生の低減化研究

  4. タングステン素材を用いた放射線防護材料の開発と評価

Research History 9

  1. Nagoya University   Institute of Materials and Systems for Sustainability Division of Materials Research   Associate professor

    2015.10

  2. Nagoya University   Eco-Topia Science Institute   Associate professor

    2013.10 - 2015.9

      More details

    Country:Japan

  3. 三重大学    工学部分子素材工学科   非常勤講師

    2012.4

      More details

    Country:Japan

  4. 名古屋大学     大学院工学研究科 応用化学分野   准教授

    2007.4

      More details

    Country:Japan

  5. 名古屋大学    大学院工学研究科 化学・生物工学専攻 応用化学分野    助教授

    2004.7 - 2007.3

      More details

    Country:Japan

  6. Nagoya University   Lecturer

    2001.6 - 2004.6

      More details

    Country:Japan

  7. Nagoya University   Assistant

    1998.4 - 2001.5

      More details

    Country:Japan

  8. Japan Atomic Energy Research Institute   Advanced Science Research Center   Postdoctral fellow

    1997.4 - 1998.3

      More details

    Country:Japan

  9. University of Houston, TX, USA   Department of Chemistry,   Postdoctral Fellow

    1995.5 - 1997.1

▼display all

Education 3

  1. Hokkaido University   Graduate School, Division of Engineering

    - 1995

      More details

    Country: Japan

  2. Hokkaido University   Graduate School, Division of Engineering

    - 1995

      More details

    Country: Japan

  3. Hokkaido University   Faculty of Engineering

    - 1989

      More details

    Country: Japan

Professional Memberships 13

  1. Japanese Society of Radiation Chemistry   director

    2003.4

  2. 日本放射線影響学会

  3. Catalyst Society of Japan

    2013.8

  4. Atomic Energy Society of Japan

    2017.10

  5. The Society of Electron Spin Science and Technology

    2002.4

  6. Japanese Cancer Association

  7. The Chemical Society of Japan

    2005.4 - 2006.3

  8. 東海化学工業会   幹事(2017〜2020)

    2005

  9. Japanese Society of Radiation Chemistry

  10. 日本放射線影響学会

  11. The Society of Electron Spin Science and Technology

  12. Japanese Cancer Association

  13. Radiation Research Society

▼display all

Committee Memberships 4

  1. 日本放射線化学会編集委員会   編集主任  

    2018.4   

      More details

    Committee type:学協会

  2. 東海化学工業会   幹事  

    2017.4   

      More details

    Committee type:学協会

    2018年度庶務幹事

  3. 第53回放射線化学討論会実行委員会   大会実行委員長  

    2010.4 - 2010.9   

  4. 日本放射線化学会   理事  

    2002.4   

      More details

    Committee type:学協会

Awards 2

  1. Incentive Award

    2002.10  

     More details

    Country:Japan

  2. Insentive Award

    2004.11  

     More details

    Country:Japan

 

Papers 66

  1. Effects of the amount of Au nanoparticles on the visible light response of TiO2 photocatalysts

    Yoshida Tomoko, Misu Yuhei, Yamamoto Muneaki, Tanabe Tetsuo, Kumagai Jun, Ogawa Satoshi, Yagi Shinya

    CATALYSIS TODAY   Vol. 352   page: 34 - 38   2020.8

     More details

    Publishing type:Research paper (scientific journal)   Publisher:Catalysis Today  

    DOI: 10.1016/j.cattod.2019.12.035

    Web of Science

    Scopus

  2. Exploiting single-electron transfer in Lewis pairs for catalytic bond-forming reactions

    Aramaki Yoshitaka, Imaizumi Naoki, Hotta Mao, Kumagai Jun, Ooi Takashi

    CHEMICAL SCIENCE   Vol. 11 ( 17 ) page: 4305 - 4311   2020.5

     More details

    Publishing type:Research paper (scientific journal)   Publisher:Chemical Science  

    DOI: 10.1039/d0sc01159b

    Web of Science

    Scopus

  3. Development and verification of radio protective materials by using Tungsten fiver Invited

    Taishi Tsuda, Shigefumi Imai, Jun Kumagai

      Vol. 107   page: 65-68   2019.4

     More details

    Language:Japanese  

  4. Fundamental study of radiosensitization targeting cancer cell environmental factors

    Kashino Genro, Kumagai Jun

    CANCER SCIENCE   Vol. 109   page: 751-751   2018.1

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    Web of Science

  5. Interface of Radiation Chemistry for Radia- tion Biology and Meteorology Invited Reviewed

    Jun Kumagai

    RADIOISOTOPES   Vol. 66   page: 489-496   2017.10

     More details

    Authorship:Lead author   Language:Japanese  

    DOI: 10.3769/radioisotopes.66.489

  6. Iodide Selectivity and gamma-Ray Shielding Ability of a Layered Double Hydroxide

    Ryo Sasai, Eisaku Nii, Hiroaki Sato, Takuya Fujimura, Shigefumi Imai, Jun Kumagai

    CHEMISTRY LETTERS   Vol. 45 ( 12 ) page: 1409-1411   2016.10

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1246/cl.160775

  7. Solar-UV-signature mutation prefers TCG to CCG: extrapolative consideration from UVA1-induced mutation spectra in mouse skin Reviewed

    H. Ikehata, J. Kumagai, T. Ono, A. Morita

    Photochem. Photobiol. Sci.   Vol. 12 ( 8 ) page: 1319-27   2013.7

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    UVA1 exerts its genotoxicity on mammalian skin by producing cyclobutane pyrimidine dimers (CPDs) in DNA and preferentially inducing solar-UV-signature mutations, C T base substitution mutations at methylated CpG-associated dipyrimidine (Py-mCpG) sites, as demonstrated previously using a 364 nm laser as a UVA1 source and lacZ-transgenic mice that utilize the transgene as a mutational reporter. In the present study, we confirmed that a broadband UVA1 source induced the same mutation profiles in mouse epidermis as the UVA1 laser, generalizing the previous result from a single 364 nm to a wider wavelength range of UVA1 (340-400 nm). Combined with our previous data on the mutation spectra induced in mouse epidermis by UVB, UVA2 and solar UVR, we proved that the solar-UV-signature mutation is commonly observed in the wavelength range from UVB to UVA, and found that UVA1 induces this mutation more preferentially than the other shorter wavelength ranges. This finding indicates that the solar-UV-signature mutation-causing CPDs, which are known to prefer Py-mCpG sites, could be produced with the energy provided by the longer wavelength region of UVR, suggesting a photochemical reaction through the excitation of pyrimidine bases to energy states that can be accomplished by absorption of even low-energy UVR. On the other hand, the lower proportions of solar-UV-signature mutations observed in the mutation spectra for UVB and solar UVR indicate that the direct photochemical reaction through excited singlet state of pyrimidine bases, which can be accomplished only by high-energy UVR, is also involved in the mutation induction at those shorter wavelengths of UVR. We also found that the solar-UV signature prefers 5'-TCG-3' to 5'-CCG-3' as mutational target sites, consistent with the fact that UVA induces CPDs selectively at thymine-containing dipyrimidine sites and that solar UVR induces them preferably at Py-mCpG sites. However, the mutation spectrum in human p53 gene from non-melanoma skin cancers shows the opposite preference for 5'-CCG-3' sites. This apparent discrepancy in the site preference seems to result from the lack of 5'-TCG-3' sites mutable to missense mutations on the nontranscribed strand of human p53 gene, which should be evolutionally acquired under selective pressure from the sun.

    DOI: 10.1039/c3pp25444e

  8. Suppressive effect of ascorbic acid on the mutagenesis induced by the bystander effect through mitochondrial function Reviewed

    G. Kashino, Y. Tamari, J. Kumagai, K. Tano, M. Watanabe

    Free Radic. Res.   Vol. 47 ( 6-7 ) page: 474-479   2013.7

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    We focused on suppressive effect of ascorbic acid (AsA) on changes in mitochondrial function and mutagenesis by the radiation-induced bystander eff ect (RIBE). In mammalian cell lines, medium transfer assay was performed and conditioned medium including secreted factors after X-irradiation were examined to detect the RIBE. We found that the membrane potential and increased levels of superoxide radical (O-2(-)) in mitochondria were modulated in cells treated with conditioned medium from irradiated cells. The result of the present study also demonstrated that increases in reactive oxygen species (ROS) levels led to the induction of gene mutations. Interestingly, the modulations in mitochondria, in addition to mutation inductions by RIBE, were completely suppressed by treatment with AsA in cells treated with conditioned medium. These results suggest that mutagenesis, which may have resulted from secreted factors involving the RIBE, may be induced by ROS that are localized in mitochondria and may be relieved by AsA.

    DOI: 10.3109/10715762.2013.791025

  9. Reaction Mechanism of Aromatic Ring Amination of Benzene and Substituted Benzenes by Aqueous Ammonia over Platinum-Loaded Titanium Oxide Photocatalyst Reviewed

    H. Yuzawa, J. Kumagai, H. Yoshida

    J. Phys. Chem. C   Vol. 117 ( 21 ) page: 11047-11058   2013.5

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/jp3127658

  10. A heterogeneous palladium catalyst hybridised with a titanium dioxide photocatalyst for direct C-C bond formation between an aromatic ring and acetonitrile Reviewed

    H. Yoshida, Y. Fujimura, H. Yuzawa, J. Kumagai, T. Yoshida

    Chem. Commun.   Vol. 49 ( 36 ) page: 3793-3795   2013.3

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    A palladium catalyst hybridised with a titanium dioxide photocatalyst can promote cyanomethylation of an aromatic ring by using acetonitrile, where the photocatalyst activates acetonitrile to form a cyanomethyl radical before the C-C bond formation using the palladium catalyst.

    DOI: 10.1039/c3cc41068d

  11. Electrical properties of lead-free ferroelectric Mn-Doped K0.5Na0.5NbO3-CaZrO3 thin films prepared by chemical solution deposition Reviewed

    T. Matsuda, W. Sakamoto, B.Y. Lee, T. Iijima, J. Kumagai, M. Moriya, T. Yogo

      Vol. 51 ( 9 ) page: 09LA03   2012.9

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    Lead-free ferroelectric K0.5Na0.5NbO3-CaZrO3 thin films were prepared by chemical solution deposition. Chemically optimized K0.5Na0.5NbO3-CaZrO3 precursor thin films crystallized in the perovskite single phase on Pt/TiOx/SiO2/Si substrates at 650 degrees C. The K0.5Na0.5NbO3-CaZrO3 thin films showed poor ferroelectric polarizations due to the insufficient insulating resistance. The leakage current of the K0.5Na0.5NbO3-CaZrO3 films, especially in the high-applied-field region, was markedly reduced by 1 mol % Mn doping for the Nb site. Also, the ferroelectric properties of the K0.5Na0.5NbO3-CaZrO3 thin films depended on CaZrO3 concentration. 1 mol % Mn-doped K0.5Na0.5NbO3-CaZrO3 thin films exhibited slim and small ferroelectric polarization-electric field (P-E) hysteresis loops at room temperature with an increase in CaZrO3 amount. Furthermore, these films showed a typical field-induced displacement curve with a small hysteresis, and the estimated effective d(33) values were 32 pm/V for the 1 mol % Mn-doped 0.95K(0.5)Na(0.5)NbO(3)-0.05CaZrO(3) thin films and 21 pm/V for the 1 mol % Mn-doped 0.9K(0.5)Na(0.5)NbO(3)-0.1CaZrO(3) thin films.

    DOI: 10.1143/JJAP.51.09LA03

  12. The Bystander Effect is a Novel Mechanisms of UVA-Induced Melanogenesis Reviewed

    H. Nishiura, J. Kumagai, G. Kashino, T. Okada, K. Tano, M. Watanabe

      Vol. 88 ( 2 ) page: 389-397   2012.3

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    We successfully identified the bystander effect in B16 murine melanoma cells exposed to UVA irradiation. The effect was identified based on melanogenesis following the medium transfer of the B16 cells, which had been cultured for 24 h after being exposed to UVA irradiation, to nonirradiated cells (bystander cells). Our confirmation study of the functional mechanism of bystander cells confirmed the reduced levels of mitochondrial membrane potential 14 h after the medium transfer. In addition, we observed increased levels of intracellular oxidation after 912 h, and the generation of melanin radicals, including long-lived radicals, 24 h after medium transfer. Further analysis of bystander factors revealed that the administration of EGTA treatment at the time of medium transfer led to an inhibition of melanogenesis and to neutralization of the mitochondrial membrane potential level, as well as to the restoration of intracellular oxidation levels to those of controls. The results demonstrated that the UVA irradiation bystander effect in B16 cells, as indicated by melanogenesis, was induced by the increase in intracellular oxidation due to the mitochondrial activity of calcium ions, which were among the bystander factors involved in the increase.

    DOI: 10.1111/j.1751-1097.2011.01046.x

  13. 放射線誘導長寿命ラジカルが DNA 損傷を起源としない発がん経路の引き金 Invited Reviewed

    渡邉正己, 菓子野元郎, 熊谷 純

    放射線化学   Vol. 93   page: 15-22   2012.3

     More details

    Language:Japanese  

  14. Negative and positive ion trapping by isotopic molecules in cryocrystals in case of solid parahydrogen containing electrons and H6+ radical cations Reviewed

    Y. Shimizu, M. Inagaki, T. Kumada, J. Kumagai

      Vol. 132 ( 24 ) page: 244503   2010.6

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    We performed electron spin resonance studies of trapped electrons and H-6(+) radical cations produced by radiolysis of solid parahydrogen (p-H-2), p-H-2-ortho-D-2 (o-D-2), and p-H-2-HD mixtures. Yields of trapped electrons, H-6(+) radical cations, and its isotopic analogs H6-nD(n)(+) (4 >= n >= 1) increased with increasing o-D-2 and HD concentrations in solid p-H-2. Electrons were found trapped near an o-D-2 or an HD in solid p-H-2 due to the long-range charge-induced dipole and quadrupole interactions between electrons and isotopic hydrogen molecules. H-6(+) radical cations diffuse in solid p-H-2 by repetition of H-6(+)+H-2 -> H-2+H-6(+) and are trapped by ortho-D-2 or HD to form H6-nDn+ (4 >= n >= 1) as isotope condensation reactions. Decay behaviors of these cations by the repetition, isotope condensation, and geminate recombination between electrons and H6-nDn+ (4 >= n >= 0) were reproduced by determining the corresponding reaction rate constants k(1), k(2), and k(3). Values of 0.045 and 0.0015 L mol(-1) min(-1) were obtained for k1 (H-6(+)+D-2 -> H-2+H4D2+) and k(2) (H4D2++D-2 -> H-2+H(2)D4+), respectively, and the value was quasinull for k(3) (H(2)D4++D-2 -> H-2+D6+). These rate constants suggest that hole mobility drastically decreased in the repetition reaction when H-6(+) radical cations acting as hole carriers formed H4D2+ or H(2)D4+. HD and D-2 molecules, therefore, act as electron and hole acceptors in irradiated solid p-H-2-o-D-2 and p-H-2-HD mixtures.

    DOI: 10.1063/1.3432780

  15. 照射培地移動による放射線バイスタンダー効果を遅発性長寿命ラジカルから探る Reviewed

    熊谷 純、菓子野元郎

    放射線化学   Vol. 89   page: 20-24   2010.3

     More details

    Authorship:Lead author   Language:Japanese  

  16. Improvement in Ferroelectric Properties of Chemically Synthesized Lead-Free Piezoelectric (K,Na)(Nb,Ta)O3 Thin Films by Mn Doping Reviewed

    N. Kondo,W . Sakamoto, B.Y. Lee, T. Iijima, J. Kumagai, M. Moriya T. Yogo

    Jpn. J. Appl. Phys.   Vol. 49   page: 09MA04   2010

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

  17. *固体パラ水素中の H6+同位体イオンと 捕捉電子の放射線化学 Invited Reviewed

    清水裕太、熊谷 純

    放射線化学   Vol. 87   page: 23-33   2009.3

     More details

    Authorship:Lead author   Language:Japanese  

  18. Electron spin resonance spectroscopy of molecules in large precessional motion: A case of H6+ and H4D2+ in solid parahydrogen Reviewed

    Yuta Shimizu, Takayuki Kumada, Jun Kumagai

    J. Mag. Reson.   Vol. 194 ( 1 ) page: 76–80   2008.9

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    We have measured electron spin resonance (ESR) spectra of H-6(+) and H4D2+ tons produced in gamma-ray irradiated solid parahydrogen. Anisotropic hyperfine-coupling constants for H-6(+) and H4D2+ determined by the analysis of ESR lines at 4.2 K were -0.06 and -0.12 mT, respectively, which were opposite in sign to and much smaller than theoretical results of 1.17-1.25 mT. Although no change was observed in H-6(+), the constant for H4D2- increased to be 1.17 mT at 1.7 K, which is very close to the theoretical value. We concluded that H-6(-) both at 4.2 and 1.7 K and H4D2+ at 4.2 K should be in a large precessional motion with the angle of 57-59 degrees, but the precession of H4D2+ is stopped at 1.7 K.

    DOI: 10.1016/j.jmr.2008.05.024

  19. *放射線照射後に細胞中で生じてくる遅発性長寿命ラジカルと遅延放射線生物影響 Invited

    熊谷 純

    電子スピンサイエンス   Vol. 6 ( 11 ) page: 109-115   2008.9

     More details

    Authorship:Lead author   Language:Japanese  

  20. H atom, e(-), and H(6)(+) ions produced in irradiated solid hydrogens: An electron spin resonance study Reviewed

    T. Kumada, Y. Shimizu, T. Ushida, J. Kumagai

    Radiat. Phys. Chem.   Vol. 77 ( 10-12 ) page: 1318-1322   2008

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    We carried out electron spin resonance (ESR) study of irradiated solid H(2) and para-H(2). H-atom, e(-), and H(6)(+) lines were observed. The H-atom radicals diffuse in solid H2 by the tunneling chemical reaction H+H(2) -> H(2)+H below 4 K, and by the thermally activated process above 5 K. These decay via H-H recombination. Yield of trapped electrons e- produced by the radiolysis of solid para-H2 increases with increase in the concentration of added isotopic hydrogen, HD or D(2). These decay via geminate recombination with positive ions with a half-life of 8 h at 4 K. H(6)(+) ion is an ionic hydrogen radical whose spectrum has firstly been observed in irradiated solid para-H(2). H(6)(+) ions diffuse in solid H2 by sequence of H(6)(+)+H(2) -> H(2)+H(6)(+) reactions, and terminate by the isotope-exchange reaction H(6)(+)+HD -> H(5)D(+)+H(2) or H(6)(+)D(2) -> H(4)D(2)(+)+H(2). Unlike H(6)(+), isotopically substituted H(5)D(+) and H(4)D(2)(+) cannot diffuse in solid para-H(2). Rate-determining step of their decay is charge recombination with e(-).

    DOI: 10.1016/j.radphyschem.2008.05.026

  21. 放射線照射後に細胞中で生じてくる遅発性長寿命ラジカルと遅延放射線生物影響 Invited

    熊谷 純

    電子スピンサイエンス   Vol. 6   page: 109-115   2008

     More details

    Authorship:Lead author   Language:Japanese  

  22. Electron spin resonance study on H6+, H5D+, H4D2+, and H2D4+ in solid parahydrogen Reviewed

    Jun Kumagai, Hiroki Inagaki, Susumu Kariya, Takahiro Ushida, Yuta Shimizu, Takayuki Kumada

    J. Chem. Phys.   Vol. 127 ( 2 ) page: 024505   2007.7

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    We carried out an electron spin resonance (ESR) study on hydrogen ion radicals produced by radiolysis of solid para-H-2. In addition to quartet ESR lines proposed to be H-2(+)-core H-6(+) (D-2d) ions in solid para-H-2 [T. Kumada , Phys. Chem. Chem. Phys. 7, 776 (2005)], we newly observed totally more than 50 resolved lines in gamma-ray irradiated solid para-H-2-ortho-D-2 (1 mol %) and para-H-2-HD (1 mol %) mixtures. We assigned these lines to be isotope substituents of H-2(+)-core H-6(+) ions such as H5D+, H4D2+, and H2D4+ throughout the comparison of their ESR parameters with theoretical results. These results provide a conclusive evidence that H-2(+)-core H-6(+) ions are generated in irradiated solid hydrogens. Analysis of the EPR spectrum and ab initio calculations predicts D-2d symmetry of the H-6(+) ions, whereas a lowering symmetry (D-2d -> C-2v) induced by asymmetric nuclear wave function is observed in H5D+ and H4D2+. We also observed isotope-substitution reactions such as H-6(+)+D-2 -> H4D2++H-2 and H-6(+)+HD -> H5D++H-2, which are analogous to the well-known isotope-condensation reactions of H-3(+) in dark nebula, H-3(+)+HD -> HD2++H-2 and HD2++HD -> D-3(+)+H-2.

    DOI: 10.1063/1.2748046

  23. 固体パラ水素中に生成したH6+のESR分光研究 Reviewed

    熊田高之、牛田考洋、清水裕太、熊谷 純

    電子スピンサイエンス   Vol. 5   page: 134-139   2007

     More details

    Language:Japanese  

  24. ESR study of H6+ and H4D2+ produced in irradiated solid hydrogens Reviewed

    T. Kumada, T. Takayanagi, J. Kumagai

    J. Mol. Struc.   Vol. 786 ( 2-3 ) page: 130-133   2006.4

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    We reinvestigated the quartet ESR lines with g-valueg=2.002 and hyperfine coupling constant A approximate to 20 mT produced in gamma-ray irradiated solid pH, in order to determine to which the lines should be assigned, H-2(-) or H-6(+). We newly found further splitting of each of the quartet lines into quintet ones in irradiated solid p-H-2 containing o-D-2 at 1 mol%. ESR parameters of these new lines were found to be consistent with those of H4D2+ calculated. This result supports the assignment to H-6(+) rather than H-2(-).

    DOI: 10.1016/j.molstruc.2005.08.036

  25. Is the ESR spectrum attributable to H2- or H2+(H2)2? Precise measurement of the g-value and anisotropic hyperfine structure in gamma-irradiated solid parahydrogen Reviewed

    Jun Kumagai, Masatsugu Hanabusa, Hiroki Inagaki and Susumu Kariya

    Phys. Chem. Chem. Phys.   Vol. 6 ( 17 ) page: 4363-4368   2004.6

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    Four ESR lines, found by Miyazaki et al. in 1995 in irradiated solid parahydrogen (ca. 92% para-purity) at 4.2 K, assigned as "H-2(-),'' were precisely re-measured with highly pure solid parahydrogen (>99.9%) and compared with calculated g-value and hyperfine coupling constants of H-2(+)(H-2)(2). The g-value of I,M-I=0,0 feature, reported previously as 2.0033 or 2.0023, was found to be incorrect and has now been corrected to 2.002120+/-0.000012. This corrected value is clearly smaller than that of free electron. We also found that the remaining three lines corresponding to I, M-I=1,0; 1, +1; and 1, -1 features have axially symmetric hyperfine anisotropic structure i.e., A(parallel to)=20.318 and A(perpendicular to)=20.502 mT. This anisotropy corresponds to the rotation of the species in solid parahydrogen. Although the experimental g-value and isotropic hyperfine coupling constants are in good agreement with those of H-2(+)(H-2)(2) estimated by ab initio calculation, it is still difficult to explain why H-2(+)(H-2)(2) clusters turned into ESR inactive species by addition of 0.1similar to1% D-2 in the present system. In this regard, we still maintain that the species in solid parahydrogen are H-2(-).

    DOI: 10.1039/b402756f

  26. Long-lived mutagenic radicals induced in mammalian cells by ionizing radiation are mainly localized to proteins Reviewed

    J. Kumagai, K. Masui, Y. Itagaki, M. Shiotani, S. Kodama, M. Watanabe, T. Miyazaki

    Radiat. Res.   Vol. 160 ( 1 ) page: 95-102   2003.7

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    We have provided evidence that long-lived radicals, produced by ionizing radiation, are highly mutagenic and transforming in mammalian cells. Long-lived radicals are scavenged effectively by vitamin C or by epigallocatechin-3-O-gallate (EGCG). Long-lived radicals are not involved in lethality or in the induction of chromosome aberrations. We now report the results of experiments that define the relative amounts of long-lived radicals in DNA and proteins and identify the major protein radicals as sulfinyl radicals (R-CH2-S-O-.). To make these assignments, yields of long-lived radicals in gamma-irradiated salmon sperm DNA and albumin were compared by ESR. ESR spectra of long-lived radicals produced in irradiated Syrian hamster embryo (SHE) cells were analyzed precisely and compared with ESR parameters obtained by density functional theory calculations. Long-lived radicals yields of 99.8% were produced in proteins. We also identified a new type of long-lived radical as H-added phenylalanine radicals. While our evidence does not rule out the possibility of important biological consequences of the low-level long-lived radicals created by radiation, it implicates radicals in proteins as playing a key role in genetic effects of ionizing radiation. We suggest that these novel radicals, wherever they reside, need to be considered in explanations of biological sequela of radiation.

    DOI: 10.1667/RR3015

  27. Active sites and active oxygen species for photocatalytic epoxidation of propene by molecular oxygen over TiO2-SiO2 binary oxides Reviewed

    C. Murata, H. Yoshida, J. Kumagai, T. Hattori

    J. Phys. Chem. B   Vol. 107 ( 18 ) page: 4364-4373   2003.5

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    TiO2-SiO2 binary oxides of low Ti content promoted photocatalytic epoxidation of propene by molecular oxygen. By catalytic runs and UV spectra, it was revealed that the isolated tetrahedral Ti species on the TiO2-SiO2 samples are active for the photoepoxidation of propene, while the aggregated titanium oxide species are active mainly for the side reactions. By ESR and stoichiometric reaction tests of radical species, the following mechanism was proposed. Over the isolated tetrahedral Ti species, a [Ti3+-O-L(-)]* radical pair is formed by UV irradiation. The Ti3+ moiety reacts with O-2 to form O-2(-), which could not activate propene by itself. The O-L(-) moiety, a hole center on lattice oxygen, reacts with O-2 to form O-3(-), and the O-3(-) reacts with propene to yield PO. It is first suggested that the O-3(-) is the electrophilic oxygen species effective for the epoxidation of propene. When the O-L(-) moiety reacts with propene, acrolein or ethanal is produced through H abstraction or CC bond fission. The lower selectivity of the aggregated titanium oxide species was attributed to the lower stability of the O-3(-) and high activity for the consecutive reaction of PO.

    DOI: 10.1021/jp0277006

  28. Test for antioxidant ability by scavenging long-lived mutagenic radicals in mammalian cells and by blood test with intentional radicals: an application of gallic acid Reviewed

    J. Kumagai, T. Kawaura, T. Miyazaki, M. Prost, E. Prost, M. Watanabe, J. Q. Leclercq

    Radiat. Phys. Chem.   Vol. 66 ( 1 ) page: 17-25   2003.1

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    Antioxidant ability of gallic acid (GA) are determined both by electron spin resonance measurement of long-lived radicals produced in gamma-ray irradiated Syrian golden hamster embryo cells with GA and by hemolysis measurement with GA when blood cells are submitted to radicals. Scavenging properties of GA are determined by the reaction rate constant with long-lived mutagenic radicals in the cells while the blood test allows to analyze the global effects of this compound: radical scavenger + metal ion chelator + regeneration of intra- and extra-cellular antioxidant.

    DOI: 10.1016/S0969-806X(02)00288-8

  29. 磁気共鳴法を用いた照射生体中の長寿命ラジカルの観測と生物効果との関連性の解明 Invited Reviewed

    熊谷 純

    放射線化学   Vol. 75   page: 3-11   2003

     More details

    Language:Japanese  

  30. Long-lived radicals produced by gamma-irradiation or vital activity in plants, animals, cells, and protein solution: their observation and inhomogeneous decay dynamics Reviewed

    T. Miyazaki, A. Morikawa, J. Kumagai, M. Ikehata, T. Koana, S. Kikuchi

    Radiat. Phys. Chem.   Vol. 65 ( 2 ) page: 151-157   2002.9

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    Long-lived radicals produced by gamma-irradiation or vital activity in plants, animals, cells, and protein (albumin) solution were studied by electron spin resonance spectroscopy. Long-lived radicals produced by vital activity exist in biological systems, such as plants, animals, and cells, in the range of 0.1-20 nmol g(-1). Since vital organs keep the radicals at a constant concentration, the radicals are probably related to life conservation. Long-lived radicals are also produced by gamma-irradiation of cells or protein solution. The radicals decay after death of living things or after gamma-irradiation. We found that the decay dynamics in all biological systems can be expressed by the same kinetic equation of an inhomogeneous reaction

    DOI: 10.1016/S0969-806X(02)00198-6

  31. Suppression and enhancement of tunneling ion recombination of electron bubbles in solid para-hydrogen-ortho-hydrogen mixtures at 4.2 K: controlling factors of tunneling reaction Reviewed

    T. Miyazaki, H. Fukuta, M. Hanabusa, T. Kumada, J. Kumagai

    Chem. Phys. Lett.   Vol. 360 ( 1-2 ) page: 8-12   2002.7

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    The decay of electron bubbles due to a tunneling ion recombination was studied by ESR in gamma-ray irradiated solid para-hydrogen (p-H-2)-ortho-hydrogen (o-H-2) mixtures at 4.2 K. In the range of 10-75% o-H-2 (region I), the decay rates of the electron bubbles increase with decreasing o-H-2 concentration. The decay rate constant shows the maximum around 10% o-H-2. Then, the decay rates decrease with decreasing o-H-2 concentration below 10% o-H-2 (region II). The results were interpreted by two different rate-determining steps: a tunneling process in region I and an energy-dissipation process in region II. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0009-2614(02)00823-0

  32. Scavenging of long-lived radicals by (-)-epigallocatechin-3-O-gallate and simultaneous suppression of mutation in irradiated mammalian cells Reviewed

    J. Kumagai, M. Nakama, T. Miyazaki, T. Ise, S. Kodama, M. Watanabe

      Vol. 64 ( 4 ) page: 293-297   2002.7

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    Effect of (-)-epigallocatechin-3-O-gallate (EGCg) on scavenging long-lived radicals and its biological significance were investigated using electron-spin-resonance spectroscopy and mutation assay in cultured human embryo cells. EGCg scavenged long-lived radicals in irradiated golden hamster embryo cells and albumin solution, and simultaneously reduced mutation frequency in the irradiated human embryo cells. These results indicate that long-lived radials are involved in the induction of mutation by radiation.

    DOI: 10.1016/S0969-806X(01)00501-1

  33. Absence of recombination of neighboring H atoms in highly purified solid parahydrogen: Electron spin resonance, electron-nuclear double resonance, and electron spin echo studies Reviewed

    T. Kumada, M. Sakakibara, T. Nagasaka, H. Fukuta, J. Kumagai, T. Miyazaki

    J. Chem. Phys.   Vol. 116 ( 3 ) page: 1109-1119   2002.1

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    Diffusion and recombination of H atoms were studied in solid hydrogen containing ortho-H(2) molecules at relative concentration X(o)=0.001 -->0.75 using electron spin resonance (ESR), electron-nuclear double resonance (ENDOR), and electron spin echo (ESE) methods at around 4 K. When the rate-determining step for recombination is assumed to be the diffusion of H atoms, the rate constant for recombination at X(o)greater than or equal to0.1 is consistent with the diffusion coefficient estimated from the analysis of ENDOR spectra and longitudinal spin relaxation behaviors. The recombination rate constant at X(o)<0.1, however, is too slow to be explained using the diffusion coefficient estimated from longitudinal spin relaxation and forbidden spin-flip satellite transition studies. This result suggests that, even if one H atom finds another H in its immediate neighborhood, these H atoms do not react to form a H(2) molecule at X(o)<<0.1. The absence of recombination of H atoms is due to lack of the energy dispersion path required for the recombination of diatomic molecules. Since the absence of recombination becomes less significant at higher X(o), ortho-H(2) molecules are found to play an important role in the energy dispersion which accompanies the recombination reaction

    DOI: 10.1063/1.1426410

  34. An ESR and ESEEM study of long-lived radicals which cause mutation in irradiated mammalian cells Reviewed

    J. Kumagai, T. Miyazaki, S. Kodama, M. Watanabe

    Int. Congress Series   Vol. 1236   page: 351-354   2002

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

  35. A role of long-lived radicals in radiation mutagenesis and its suppression by epigallocatechin gallate Reviewed

      Vol. 1236   page: 355-358   2002

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

  36. 突然変異やガン化を誘発する長寿命タンパク質ラジカル 〜電子スピン共鳴法・電子スピンエコー法による解析〜 Invited

    熊谷 純

    放射線生物研究   Vol. 37   page: 85-103   2002

     More details

    Authorship:Lead author   Language:Japanese  

  37. High-resolution electron spin resonance spectroscopy of ethyl radicals in solid parahydrogen Reviewed

    T. Kumada, J. Kumagai, T. Miyazaki

    J. Chem. Phys.   Vol. 114 ( 22 ) page: 10024-10030   2001.6

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    High-resolution electron spin resonance (ESR) spectrum of ethyl radicals isolated in solid parahydrogen (> 99.5 mol %) has been measured in the temperature range between 3.1 and 6.7 K. This study was carried out by UV photolysis of ethyl iodide doped in solid parahydrogen. Although ESR linewidth of the spectrum is broadened due to anisotropic terms of hyperfine interactions, the linewidth measured in parahydrogen remains comparable to that of the isotropic spectrum measured in liquid ethane [R. W. Fessenden, J. Chem. Phys. 37, 747 (1962)]. Small splittings were found in the resolved ESR signals and assigned as ethyl radicals with A(A',A') and E(E',E') symmetries, respectively. The ratio in the ESR intensities is not proportional to that of the degeneracy of each symmetry but varies as a function of temperature. We measured the signal intensities as a function of temperature and determined the rotational energy level splitting of methyl groups between the lowest with the A(A('),A(')) symmetry and the second-lowest with the E(E-',E-') symmetry in solid parahydrogen to be 5.3 +/-0.7 K. The level splitting is close to that measured by infrared-absorption study in gas phase and theoretical calculation, whereas the splitting measured in conventional matrices have been much smaller. Intermolecular interaction between guest radicals and surroundings in solid parahydrogen are found to be much smaller than those in other conventional matrices giving less shifted spectral parameters.

    DOI: 10.1063/1.1370080

  38. ESR, ENDOR and ESEEM spectroscopy study on local structure and motion of reactants: highly selective tunneling radical abstraction in neopentane-ethane mixture Reviewed

    Jun Kumagai, Yoshiteru Itagaki, Masanobu Ishizuka, Takayuki Kumada, Anders Lund, Tetsuo Miyazaki

    J. Phys. Chem. A   Vol. 105 ( 14 ) page: 3652-3657   2001.4

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    Local structures and motions of radical reactants in highly selective tunneling abstraction reaction in neopentane-ethane mixture are investigated with CW-ESR, ENDOR, and ESEEM spectroscopy at different temperatures. H atoms produced by the radiolysis of neo-C5H12 in the neo-C5H12-C2H6 (2 mol %) mixtures above 40 K react selectively with the solute C2H6 to give ethyl radicals. The selective reaction is suppressed below 30 K. The local structures of neopentane matrix around neopentyl and ethyl radicals are approximately the same in the temperature range from 4.4 to 45 K. Although neopentyl radicals are rigidly trapped below 100 K, ethyl radicals in neopentane matrix begin to librate even at 6 K and increase the degree of motion up to 30 K, Finally, the librating motion of the ethyl radicals in neopentane matrix is vigorous above 40 K. The ethane molecule can take more favorable orientation for the hydrogen abstraction reaction by H atoms than rigid neopentane molecules by the vigorous libration motion, resulting in the selective reaction with H atoms.

    DOI: 10.1021/jp003396+

  39. Controlling factors of tunneling reactions in solid hydrogen at very low temperature Reviewed

    Tetsuo Miyazaki, Jun Kumagai, Takayuki Kumada

    Radiat. Phys. Chem.   Vol. 60 ( 4-5 ) page: 381-387   2001.3

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    The recent studies on tunneling reactions: of our group are;auto-reviewed. The local structure around reactants, the new temperature effect. and the impurity effect are pointed out as important controlling factors of tunneling reactions in the solid phase. The distances between H(D) atoms and H-2(HD. D,) molecules in solid hydrogen and solid argon M ere estimated by ESR, electron nuclear double resonance (ENDOR), and electron spin echo (ESE). The temperature effects on tunneling reaction were observed in a reaction D + HD --> D-2 + H in solid HD. A mechanism of a vacancy-assisted tunneling reaction has been proposed to account for the temperature effect. The strange temperature dependence of a tunneling electron-transfer-reaction H-2(-) + H-2 + H-2(-) was explained in terms elf the phonon-scattering effect and the impurity effect on the tunneling reaction. The rate constant fur a tunneling reaction H + p-H-2 --> p-H-2 + H in solid para-H-2 (p-H-2) decreases with the increase in the concentration of ortho-H-2 (o-H-2). The results were explained by the model that the orientational defects: by o-H-2 molecules affect the tunneling reaction H + p-H-2. A tunneling reaction at very low temperature gives a surprising example in control of a reaction that a small amount of energy as such 2 cal mol(-1) can affect the rate of a reaction. The tunneling reaction in the solid phase. which can be considered as a multidimensional tunneling phenomenon. is affected significantly by the condition surrounding reactants.

    DOI: 10.1016/S0969-806X(00)00413-8

  40. Resonance effect on the tunneling reaction: H+H2 -> H2+H in solid hydrogen Reviewed

    T. Kumada, S. Mori, T. Nagasaka, J. Kumagai, T. Miyazaki

    J. Low Temp. Phys.   Vol. 122 ( 3-4 ) page: 265-277   2001.2

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    The tunneling abstraction reaction: H + H-2 --> H-2 + H in gamma -irradiated solid hydrogen has been studied using electron spin resonance (ESR) and electron-nuclear double resonance (ENDOR) spectroscopy and gas-chromatography. The rate constant for the tunneling reaction in solid hydrogen was found to decrease with the increase in the concentration of ortho-H-2 molecules in solid hydrogen. We concluded that the decrease in the rate constant is clue to the energy level mismatching between reactant species of H + H-2 trapped and product species of H-2 + H trapped in the reverse induced by inhomogeneous intermolecular interactions between ortho-H-2 molecules in solid hydrogen. This result indicates that resonance effects play an important role in tunneling reactions in solids.

    DOI: 10.1023/A:1004840631947

  41. Electron spin echo study of long-lived radicals which cause mutation in gamma-ray irradiated mammalian cells. Reviewed

    Jun Kumagai, Takayuki Kumada, Masami Watanabe, Tetsuo Miyazaki

    Spctrochimica Acta. A.   Vol. 56 ( 13 ) page: 2509-2516   2000.11

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    Long-lived radicals, produced by gamma -ray irradiation of mammalian cells at room temperature, cause mutation and morphological transformation in the cells. The local environment near the long-lived radicals in irradiated cells was investigated here by the analysis of electron spin echo envelope modulation (ESEEM) spectra. The number of hydrogen (deuterium) atoms surrounding the long-lived radical, which may correspond to the number of water molecules, was estimated roughly as one or two. It is postulated that the long-lived radicals are generated in the interior of biopolymers. The radicals are not produced by the reaction of OH radicals, but mainly by the decomposition of biopolymer which absorbed directly the energy of the ionizing radiation

    DOI: 10.1016/S1386-1425(00)00360-7

  42. Decay dynamics of H atoms in solid hydrogen at 4.2 and 2.2 K. Controlling factor of tunneling reaction H + para-H2 Reviewed

    T. Miyazaki, S. Mori, T. Nagasaka, J. KUmagai, Y. Aratono, T. Kumada

    J. Phys. Chem. A.   Vol. 104 ( 42 ) page: 9403-9407   2000.10

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    H atoms produced by the gamma -ray irradiation of solid para-H-2 (p-H-2) and solid normal-H-2 (n-H-2) decay gradually when the irradiated sample is stored at 4.2 K. ortho-H-2 (o-H-2) molecules at the sites nearest an H atom in solid n-H-2 convert to p-H-2 molecules by interacting with the H atom. H atoms in solid H-2 decay by the process of tunneling diffusion H + p-H-2 --> p-H-2 + H and finally recombine with other I-I atoms. The rate constants for the tunneling reaction were obtained from the decay rates of H atoms in solid H-2 at various concentrations of o-H-2 When solid n-H-2 is stored for 10 h at 4.2 K after gamma -ray irradiation, a number of o-H-2 molecules change into p-H-2 molecules by a catalytic chain reaction induced by mobile H atoms. The G value of the o-H-2 yields from H atoms amounts to 1-2.6 x 10(4). The rate constant for the tunneling reaction ii + p-H-2 --> p-H-2 + H decreases drastically with increasing numbers of o-H-2 molecules, which exist as orientational defects in solid p-H-2. It was concluded that a very small amount of energy (ca. 2 cal mol(-1)) affects the tunneling reaction at very low temperatures.

    DOI: 10.1021/jp000440c

  43. An ENDOR study of H atoms in HD solid at 4.2 K Reviewed

    J. Kumagai, T. Noda, T. Miyazaki

    Chem. Phys. Lett.   Vol. 321 ( 1-2 ) page: 8-12   2000.4

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    An ENDOR spectrum of H atoms in the gamma-ray irradiated HD solid was measured at 4.2 K for elucidating the local environment of HD molecules surrounding ii atoms. The analysis of the ENDOR spectrum indicates that the H atoms are not trapped in substitutional but in pseudo octahedral interstitial sites of HD solid. It is postulated that an H atom, produced by the gamma-irradiation, initially enters the octahedral interstitial site, and then the HD molecules at the first nearest site from the Ii atom are pushed back by zero-point vibration of the ii atom.

    DOI: 10.1016/S0009-2614(00)00327-4

  44. Strong resistance of Arabidopsis thaliana and Raphanus sativus seeds for ionizing radiation as studied by ESR, ENDOR, ESE spectroscopy and germination measurement: Effect of long-lived and super-long-lived radicals. Reviewed

    J. Kumagai, H. Katoh, T. Kumada, A. Tanaka, S. Tano, T. Miyazaki

    Radiat. Phys. Chem.   Vol. 57 ( 1 ) page: 75-83   2000.1

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    Resistance of seeds for ionizing radiation effects on Arabidopsis thaliana and Raphanus sativus seeds were investigated by ESR, ENDOR, ESE spectroscopy and germination measurement. Two types of free radicals, such as long-lived (LL) and super-long-lived (SL) radicals, were produced by the gamma-irradiation in the seeds. More than 90% of the 1 kGy-irradiated-seeds can germinate probably by decreasing the LL radicals by absorbing water. 10 kGy-irradiated-seeds cannot germinate at all probably due to the existence of significant amounts of the SL radicals even after absorbing water.

    DOI: 10.1016/S0969-806X(99)00306-0

  45. 長寿命ラジカルの生物効果 ~イネのUVB照射効果~ Invited

    熊谷 純、宮崎哲郎

    IGEシリーズ   Vol. 27   page: 3-12   2000

     More details

    Authorship:Lead author   Language:Japanese  

    UVB感受性の農林1号と抵抗性のササニシキの葉にUVB照射してそのESRスペクトルを観測した結果、農林1号のチロシンラジカルが減りやすくシングレットの信号が増えやすいことがわかった。

  46. Trapping sites of hydrogen atoms in solid HD and D2 : An electron spin echo study Reviewed

    T. Kumada, T. Noda, J. Kumagai, Y. Aratono, T. Miyazaki

    J. Chem. Phys.   Vol. 111 ( 24 ) page: 10974-10978   1999.12

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    Trapping sites of H and D atoms in solid HD and D-2 have been determined using electron spin echo (ESE) spectroscopy. It was found that all the H and D atoms are trapped in substitutional sites and that the H atoms push back surrounding HD(D-2) molecules to produce local lattice distortion around the atoms, whereas the D atoms do not. It is expected that the local lattice distortion is produced by zero-point motion of the H atoms whose amplitude is larger than that of host HD(D-2) molecules and that the isotope effect is due to difference in the amplitude between the H and D atoms. The lattice distortion around the H atoms may induce the increase in rate constant for the tunneling reaction D+DH --> D-2+H with the increase in temperature in solid HD reported in Chem. Phys. Lett. 261, 463 (1996).

    DOI: 10.1063/1.480461

  47. Differences in the sensitivity to UVB radiation of two cultivars of rice (Oryza sativa L.) based on observation of long-lived radicals Reviewed

    J. Kumagai, H. Katoh, T. Miyazaki, J. Hidema, T. Kumagai

    J. Radiat. Res.   Vol. 40 ( 4 ) page: 303-310   1999.12

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    Free radicals with a long lifetime were observed in the leaves of two rice cultivars (Oryza sativa L,.), Sasanishiki (UVB resistant) and Norin-1 (UVB sensitive), by electron spin resonance spectroscopy. The leaves of both cultivars grown with visible light show very similar ESR spectra composed of radical 1 (R1) and radical 2 (R2), which may be attributable to P-700 cation radicals in the reaction center of photosystem I, and tyrosine cation radicals in the reaction center of photosystem II, respectively. The ESR spectrum composed of R1 and R2 radicals in the leaves of Sasanishiki grown under visible light with supplemental UVB was similar to that in the plant grown without supplemental UVB. On the other hand, the amount of R2 radicals in the leaves of Norin-1 grown under visible light with supplemental UVB was significantly smaller than that in the plant grown without supplemental UVB. It is suggested that the loss of R2 radicals in Norin-1 upon UVB irradiation is related to the instability of the plant.

    DOI: 10.1269/jrr.40.303

  48. Observation of electron bubbles in para-H2-D2 (HD) mixtures by high-resolution ESR spectroscopy Reviewed

    T. Kumada, S. Mori, J. Kumagai, Y. Aratono, T. Miyazaki

    J. Phys. Chem. A   Vol. 103 ( 45 ) page: 8966-8968   1999.11

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    A sharp singlet signal assigned to electron bubbles was observed in gamma-irradiated solid para-H-2-D-2 (HD) mixtures by use of high-resolution ESR spectroscopy. The signal was not observed in pure para-H-2 but in the mixtures. This result indicates that the D-2 and HD molecules play an important role in the formation of the electron bubbles in para-H-2. The electron bubbles decay with a half-lifetime of about 2 h, and the decay rate constant at 4.2 K is very close to that at 2.2 K. This result shows that the electron bubbles migrate in the p-H-2 sample via quantum mechanical tunneling.

    DOI: 10.1021/jp991650w

  49. Hydrogen radical anions and electron bubbles in solid hydrogen Reviewed

    T. Ichikawa, H. Tachikawa, T. Kumada, J. Kumagai, T. Miyazaki

    Chem. Phys. Lett.   Vol. 307 ( 3-4 ) page: 283-286   1999.7

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/S0009-2614(99)00459-5

  50. Relation between the helicity and the ESR g-anisotropy of δ-conjugated quantum wires Reviewed

    T. Ichikawa, M. Sumita, J. Kumagai

    Chem. Phys. Lett.   Vol. 307 ( 1-2 ) page: 81-88   1999.6

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    We present a simple theoretical expression connecting the helicity of sigma-conjugated quantum wires with the ESR g-anisotropy of their charge carriers. The helicity of polysilanes derived from the ESR g-anisotropy of their radical ions is in good agreement with that obtained from the other structural studies.

  51. Suppression of the Anderson localization of charge carriers on polysilane quantum wire Reviewed

    T. Ichikawa, Y. Yamada, J. Kumagai, M. Fujiki

    Chem. Phys. Lett.   Vol. 306 ( 5-6 ) page: 275-279   1999.6

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    Comparison of the ESR and electronic absorption spectra of the radical ions of poly(cyclohexylmethylsilane) and poly(n-decyl-(s)-2-methylbutylsilane) has shown that the Anderson localization of charge carriers on part of the Si-Si polymer skeleton can be suppressed by replacing the pendant groups with bulky ones. Replacement reduces the flexibility of the polymer skeleton and therefore the dispersion of the resonance energies of the charge carriers between adjacent Si atoms, which suppresses the localization of the charge carriers arising from irregularity of the periodic potential field on the skeleton.

    DOI: 10.1016/S0009-2614(99)00487-X

  52. Optical and electronic properties of polysilane radical anions Reviewed

    T. Ichikawa, H. Koizumi, J. Kumagai

    J. Phys. Chem. B   Vol. 103 ( 19 ) page: 3812-3817   1999.5

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    Analyses of the electronic absorption spectra and their polarization spectra of the radical anions of permethylated hexa- and octasilane and poly(cyclohexylmethylsilane) in the mixed solvents of nonpolar methylcyclohexane and polar 2-methyltetrahydrofuran at 77 K have revealed that the orbitals of the excess electrons in the radical anions are antibonding pseudo-pi composed of Si 3p(y) atomic orbitals bisecting the Si-Si-Si planes. The near-IR and UV bands of the radical anions are assigned as being due to the excitation of an electron from the SOMO pseudo-pi(3p(y)) to pseudo-pi(3p(y)) and from the HOMO pseudo-pi(3p(x)) to antibonding-sigma(3s), respectively. The near-IR band of the polysilane radical anion shows strong solvatochromic shift, which arises from the localization of the excess electron on a part of the main chain. Localization of the excess electron is proposed to be due to Anderson localization which is induced by the fluctuation of pseudo-pi conjugation arising from the irregularity of the torsional angles of the Si-Si bonds.

    DOI: 10.1021/jp9834715

  53. Decay of H2-anions in solid parahydrogen via two-stage quantum tunneling diffusion processes Reviewed

    T. Kumada, N. Kitagawa, S. Mori, J. Kumagai, Y. Aratono, T. Miyazaki

    J. Low Temp. Phys.   Vol. 114 ( 5-6 ) page: 413-429   1999.5

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    Decay mechanism of H-2(-) anions in X(gamma)-irradiated solid para-H-2 (p-H-2) has been studied using high-resolution ESR spectroscopy in the temperature range between 1.3-6.6 K. The results are summarized as follows. First, the decay rate constant of the H-2(-) anions is not proportional to initial yields of reactive species such as cations and H atoms but proportional to the concentration of less-reactive species of HD molecules in p-H-2. This result shows that the decay of the H-2(-) anion is due to the reaction neither with cations nor H atoms but the HD molecules originally contained in the p-H-2 sample at natural abundance. Second, the decay rate constant of the H-2(-) anions increases proportionally with the increase in temperature below 3 K and decreases with the increase in temperature between 3-5 K, although it increases exponentially with the increase in temperature above 5 K. This result indicates that the decay rate constant of the H-2(-) anions is controlled by the rate constant for the diffusion of the H-2(-) anions via one-phonon assisted quantum tunneling below 3 K, two-photon scattered or assisted quantum tunneling between 3-5 K, and thermally-activated process above 5 K.

    DOI: 10.1023/A:1021850103903

  54. 突然変異や癌化を引き起こす長寿命ラジカルを電子スピンエコー法から探る Invited Reviewed

    熊谷 純

    放射線化学   Vol. 67   page: 20-25   1999

     More details

    Authorship:Lead author   Language:Japanese  

    細胞の突然変異を誘発する長寿命ラジカルの周りの環境を、電子スピンエコー法を用いて評価した。

  55. An ENDOR spectrum of H atoms in solid H2 Reviewed

    T. Kumada, N. Kitagawa, T. Noda, J. Kumagai, Y. Aratono, T. Miyazaki

    Chem. Phys. Lett.   Vol. 288 ( 5-6 ) page: 755-759   1998.5

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    An ENDOR spectrum of H atoms produced in the gamma-ray irradiated solid H-2 was measured at 4.2 K in order to elucidate the structure of the local environment of the H atoms in solid H-2. We found that the H atoms were not trapped in interstitial sites but in substitutional sites of the solid, and almost all the ortho-H(2 )molecules at the first nearest sites from the H atoms converted into para-H-2 molecules. This result shows that the ortho-para conversion is induced by electron spins of the H atoms

    DOI: 10.1016/S0009-2614(98)00296-6

  56. Temperature Effect on Selective Tunneling Abstraction Reaction by H Atoms in Neopentane-Alkane Mixtures 4-100K Reviewed

    J. Kumagai, T. Kumada, N. KItagawa, N. Morishita, T. MIyazaki

    J. Phys. Chem. A   Vol. 102 ( 17 ) page: 2842-2846   1998.4

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    When H atoms are produced by the photolysis of HI or the radiolysis of neo-C5H12 in the neo-C5H12-i-C4H10(2 mol %) mixtures above 40 K, the H atoms react selectively with the solute i-C4H10. The selective reaction is suppressed below 30 K. The reactions have been studied by electron spin resonance and electron spin echo measurements at 4-100 K. The drastic temperature effect on the reaction by H atoms suggests that the H atoms concerned are not hot atoms, but thermal atoms. The thermal H atoms react with the solute alkane by quantum tunneling at low temperature. Temperature effects on the ESR spectra and the spin-lattice relaxation times of the solvent neo-C5H11 radicals and the solute t-C4H9 radicals indicate that local motions of the solute i-C4H10 molecules take place above 40 K, while motions of the solvent neo-C5H12 molecules are severely restricted even at 100 K. It is concluded that the local motions of the solute i-C4H10 assist the tunneling abstraction reaction by H atoms, resulting in the selective reaction with the solute above 40 K.

    DOI: 10.1021/jp9801020

  57. Structure of Conduction Electrons on Polysilanes As Studied by Electron Spin-Echo Envelope Modulation Analysis Reviewed

    T. Ichikawa, H. Koizumi, J. Kumagai

    J. Phys. Chem. B   Vol. 101 ( 50 ) page: 10698-10703   1997.12

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    The orbital structures of conduction electrons on permethylated oligosilane, Si-8(CH3)(18), and poly(cyclohexylmethylsilane) have been determined by analyzing the electron spin-echo envelope modulation signals of the radical anions of these silanes in a deuterated rigid matrix at 77 K. The conduction electron on permethylated oligosilane is delocalized over the entire main chain, whereas that on poly(cyclohexylmethylsilane) is localized on a part of the main chain composed of about six Si atoms, Quantum-chemical calculations suggest that Anderson localization due to fluctuation of sigma conjugation by conformational disorder of the main chain is responsible for the localization of both the conduction electron and the hole.

    DOI: 10.1021/jp972068f

  58. Stabilization of Hydrogen Radical Anions in Solid Hydrogen Reviewed

    T.Ichikawa, H. Tachikawa, J. Kumagai, T. Kumada, T. MIyazaki

    J. Phys. Chem. A   Vol. 101 ( 40 ) page: 7315-7317   1997.10

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    The electron spin resonance g-factor of H-2(-) in gamma-irradiated crystalline H-2 was found to be not 2.003 but 2.0023, A novel model has been proposed for explaining the formation and stabilization of Hz-in crystalline H-2. The model assumes H-2(-) to be located at the center of a cavity that has previously been occupied by a trapped electron. The excess electron of H-2(-) is forced to be attached on one H-2 in the cavity due to strong repulsive interactions between the excess electron and H-2 molecules surrounding the cavity. A quantum mechanical calculation shows that an electron trapped in the vacancy of crystalline Hz automatically converts to H-2(-) by drawing one of the surrounding H-2 molecules into the center of the vacancy.

    DOI: 10.1021/jp971923s

  59. Direct observation of radical formation by charge recombination

    T. Ichikawa, K. Kagei, J. Kumagai, H. Koizumi, H. Yoshida, J. Kubo

    Radiat. Phys. Chem.   Vol. 49 ( 4 ) page: 433-436   1997.4

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    Formation of the 2,3,4-trihydronaphtyl radical from the radical cation of tetralin by charge recombination has been studied by electronic absorption spectroscopy. Illumination of the gamma-irradiated glassy alkane solution of tetralin with visible light at 77 K causes electron ejection from the radical anion of tetralin, and the ejected electron recombines with the radical cation to generate the excited tetralin, which then converts to the neutral 2,3,4-trihydronaphtyl radical. The quantum yield of the formation of the neutral radical is approximately the same as that for UV-excited tetralin, which suggests that highly excited states of tetralin are not important for the formation of the neutral radical. The highly excited tetralin molecules generated by charge recombination relax to the first excited state without any chemical reaction, and the scission of a C-H bond takes place under the first excited state.

    DOI: 10.1016/S0969-806X(96)00164-8

  60. Electronic Structure of Charge Carriers in a Polysilane Quantum Wire Reviewed

    J. Kumagai, H. Yoshida, T. Ichikawa

    Nucleonica   Vol. 42   page: 465   1997

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

  61. Interchain Migration of Electrons and Holes in Polysilanes Reviewed

    J. Kumagai, H. Tachikawa, H. Yoshida, T. Ichikawa

    J. Phys. Chem.   Vol. 100 ( 42 ) page: 16777-16778   1996.10

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    The measurements of the ESR and optical absorption spectra of polysilane radical ions revealed that the hole in the radical cation is delocalized onto the side chains, whereas the excess electron in the radical anion is confined within the silicon main chain. This observation suggests that the side chains hinder the interchain hopping of the charge for the anion but not the cation. Therefore the hole is the primary charge carrier in polysilanes.

    DOI: 10.1021/jp961004m

  62. Radical ions of oligosilane and polysilane Reviewed

    J. Kumagai, T. Ichikawa, H. Yoshida

    Radiat. Phys. Chem.   Vol. 47 ( 3 ) page: 497-499   1996.5

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    In order to elucidate electronic properties of polysilane Si-Si skeleton, the radical ions generated by gamma-irradiation of polycyclohexylmethylsilane and polymethylphenylsilane were studied by ESR and optical absorption methods. The ion radicals of permethyloligosilanes (Si-4 similar to Si-8) have also been studied for comparison. The observed results suggest that the unpaired electron is localized on a limited region of Si-Si skeleton in the polymers and it is delocalized on the whole Si-Si skeleton of the oligomers.

    DOI: 10.1016/0969-806X(95)00147-P

  63. Effect of ionizing radiation on polysilane Reviewed

    J. Kumagai, K. Oyama, H. Yoshida, T. Ichikawa

    Radiat. Phys. Chem.   Vol. 47 ( 4 ) page: 631-636   1996.4

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    ESR and gel permeation chromatographic measurements of poly(diethylsilane) and poly(cyclohexylmethylsilane) gamma-irradiated at temperatures between 77 K and 300 K were carried out to elucidate the mechanism of radiation-induced degradation of polysilanes. Radical species observed after the irradiation are not silyl-type radicals generated by the cleavage of the Si-Si bond but alkyl radicals generated by the scission of the C-H bond. The G value of the main-chain scission depends strongly on the irradiation temperature and dose. It is proposed that sigma-conjugation along the main chain allows the migration of the radiation energy to the weakest bond in the main chain where the direct scission of the bond is induced.

    DOI: 10.1016/0969-806X(95)00066-7

  64. Formation and isomerization mechanisms of M+CO2-(M=Li, Na)ion-pair complexes. An Abinitio MO and RPKM study Reviewed

    H. Tachikawa, Y. Takatori, A. Ohtake, J. Kumagai, H. Yoshida

    Theochem.   Vol. 342   page: 1-7   1995.10

     More details

    Language:English   Publishing type:Research paper (scientific journal)  

    Structures and electronic states of the M(+)CO(2)(-) (M = Li and Na) ion-pairs have been investigated by means of ab initio MO calculations. The potential energy surfaces (PESs) for the ion-pair formation reaction (M + CO2 --> M(+)CO(2)(-)) show that the ground state MCO(2) complex has a van der Waals (vdW) character (M . CO2) at the entrance region in the reaction and an ionic one (M(+)CO(2)(-)) at short M-C distances and that the activation barrier is found at the intermediate region between the vdW and ion-pair states. The wavefunctions of the ion-pair for the low-lying excited states are obtained by the multireference single and double excitation configuration interaction (MR-SD-CI) method. The first and second electronic excitations are characterized by charge-transfer transition from CO2- to Na+ and local excitation within the CO2- moiety in M(+)CO(2)(-) respectively. In order to elucidate the isomerization mechanism of the Li+CO2- ion-pair from C-s to C-2v structures, which was observed by Kafafi et al. (J. Am. Chem. Sec., 105 (1983) 3886), the Rice-Ramsperger-Kassel and Marcus (RRKM) theory is applied to calculate the microcanonical reaction rate along the reaction coordinate. The calculations strongly support their experimental results in which the reaction Li+CO2-(C-s) --> Li+CO2- (C-2v) occurs preferentially on IR irradiation.

  65. Electronic Structure of Oligosilane and Polysilane Radical Cations as Studied by Electron Spin Resonance and Electronic Absorption Spectroscopy Reviewed

    J. Kumagai, H. Yoshida, T. Ichikawa

    J. Phys. Chem.   Vol. 99 ( 20 ) page: 7965-7969   1995.5

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    The electron spin resonance (ESR) and the electronic absorption spectra of oligosilane (Si(n)R(n+1)R(n+1)', n = 2 similar to 6) radical cations in a cryogenic solid of a Freon mixture have been compared with those of poly(cyclohexylmethylsilane) and poly(methylphenylsilane) radical cations for elucidating the structure of the SOMO orbital of the radical cations or the HOMO orbitals of the neutral polysilanes, The absorption and ESR spectra of the polymer radical cations are similar to each other and also similar to those of the oligosilane radical cations, which suggests that the unpaired electron of the polymer radical cations is not delocalized all over the Si-Si main chain. The absorption spectra of the polysilane radical cations are composed of a UV and near IR bands which correspond to SOMO --> LUMO and SOMO - 1 --> SOMO, respectively. The oligosilane and the polysilane radical cations show broad isotropic ESR spectra due to hyperfine interactions with side-chain protons. Analysis of the ESR spectra shows that the unpaired electron of the polysilane radical cation is confined to only a part of the polymer chain composed of six Si atoms.

    DOI: 10.1021/j100020a019

  66. Electronec Structure of Oligosilane and Polysilane Radical Anions As Studied by Electron Spin Resonance and Electronic Absorption Spectroscopy Reviewed

    J. Kumagai, H. Yoshida, H. Koizumi, T. Ichikawa

    J. Phys. Chem.   Vol. 98 ( 50 ) page: 13117-13122   1994.12

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    The electron spin resonance (ESR) and the electronic absorption spectra of poly(cyclohexylmethylsilane) and poly(methylphenylsilane) radical anions in a cryogenic 2-methyltetrahydrofuran solid have been compared with those of permethyloligosilanes [Si-n(CH3)(2n+2), n = 4-6] for elucidating the electronic structure of polysilane radical anions. The spectra of the polysilane radical anions are very similar to each other and also to those of the oligosilane radical anions in which an unpaired electron occupies not an antibonding sigma(not asymptotic to)(sp) orbital but a pseudo-pi(p) orbital composed of antibonding Si-Si and antibonding Si-C orbitals. The polysilane radical anions show axially symmetric ESR spectra with g(perpendicular to) = 2.0023 and g(parallel to) = 2.0064 and the electronic absorption spectra composed of UV and near-IR bands. Analysis of the ESR and the absorption spectra shows that the unpaired electron of the polysilane radical anions is not delocalized all over the polymer chain but is confined in only a part of the polymer chain, probably around the elongated Si-Si bond of a branched polymer chain.

    DOI: 10.1021/j100101a005

▼display all

Books 4

  1. 放射線と安全につきあう

    西澤邦秀・柴田理尋 編( Role: Joint author)

    名古屋大学出版会  2017.5  ( ISBN:978-4-8158-0875-4

     More details

    Total pages:238   Language:Japanese Book type:Textbook, survey, introduction

  2. Applications of EPR in Radiation Research / Hydrogen Molecular Ions in Solid Parahydrogen: EPR Studies at Cryogenic Temperatures

    Jun Kumagai( Role: Sole author)

    Springer-Verlag GmbH  2014.12  ( ISBN:978-3-319-09215-7

     More details

    Language:English

  3. 放射線化学のすすめ

    日本放射線化学会編( Role: Joint author)

    学会出版センター  2006.2  ( ISBN:4-7622-3050-2

     More details

    Language:Japanese

  4. *Atom tunneling reaction of vitamin C in suppression of mutation. In: Atomic Tunneling phenomena in Physics, Chemistry, and Biology

    Tetsuo Miyazaki and J. Kumagai( Role: Joint author)

    Springer  2004 

     More details

    Language:English

MISC 2

  1. Fundamental study of radiosensitization targeting cancer cell environmental factors

    Kashino Genro, Kumagai Jun

    CANCER SCIENCE   Vol. 109   page: 751-751   2018.1

     More details

    Language:English   Publishing type:Rapid communication, short report, research note, etc. (scientific journal)  

  2. Interface of Radiation Chemistry for Radia- tion Biology and Meteorology Invited Reviewed

    Jun Kumagai

    RADIOISOTOPES   Vol. 66 ( 10 ) page: 489-496 - 496   2017.10

     More details

    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)   Publisher:Japan Radioisotope Association  

    <p>Monte carlo simulations of water radiolysis chemistry including solvation of electrons and quantitative study of DNA double strand breaks is introduced as an interface of radiation chemistry and biology. In addition experimental study for formation of cloud condensation nuclei by ionizing radiation is introduced as incredible important study for the demonstration of cloud formation by cosmic-ray, which may govern climate change of the earth.</p>

    DOI: 10.3769/radioisotopes.66.489

    CiNii Article

Presentations 15

  1. 細胞内抗酸化性を向上させる低線量放射線バイスタンダー効果 Invited

    熊谷 純

    第73回ONSA先端科学研究会 第64回放射線科学研究会 

     More details

    Event date: 2017.10.20

    Language:English   Presentation type:Oral presentation (general)  

    Venue:住友クラブ(大阪市西区江戸堀1-13-10)   Country:Japan  

  2. Radiation-Induced Bystander Effect of Normal, Cancer and Stem Cells as Studied by Long-Lived Radicals Invited International conference

    Jun Kumagai, Akane Oohashi, and Genro Kashino

    Hiroshima International Workshop on Circular Dichroism Spectroscopy 2017 -Application to Imaging Microscopy and Radiation Biology- 

     More details

    Event date: 2017.2.28

    Language:English   Presentation type:Oral presentation (invited, special)  

    Venue:Hiroshima Synchroton Radiation Center   Country:Japan  

  3. 極低温ESR分光法による水吸着した酸化チタンの酸化・還元サイトにおける素反応解析 International conference

    熊谷 純,澤井 健,吉田朋子,吉田寿雄

    第118触媒討論会 

     More details

    Event date: 2016.9.21 - 2016.9.23

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:岩手大学   Country:Japan  

  4. 培地移動放射線バイスタンダー効果における 長寿命ラジカル誘導 Invited

    熊谷 純

    第53回放射線影響懇話会 

     More details

    Event date: 2016.7.16

    Language:English   Presentation type:Oral presentation (invited, special)  

    Venue:大分市ホルトホール   Country:Japan  

  5. J. Kumagai: Long-lived radicals and their biological effects in mammalian cells and rice cultivars as studied by ESR and ESEEM spectroscopy, Society of Royal Chemistry, University Catholique de Louvain, 2000, Belgium.

  6. J. Kumagai, T. Kumada, T. Miyazaki: Temperature effect on selective tunneling abstraction reaction by H atoms in neopentane-alkane mixtures at 4-100 K, 3rd Int. Conf. on Low Temp. Chem., edited by T. Miyazaki, 1999, pp. 27-28.

  7. J. Kumagai, T. Kumada, M. Watanabe, T. Miyazaki: Electron-spin-echo study of long-lived radicals which cause DNA mutation and cancer in mammalian cells, 3rd Int. Conf. on Low Temp. Chem., edited by T. Miyazaki, 1999, pp. 137-138.

  8. J. Kumagai, H. Katoh, T. Miyazaki, J. Hidema, T. Kumagai: Differences in the sensitivity to UVB radiation of two cultivars of rice (Oryza sativa L.) based on observation of long-lived radicals, COE-IGE Int. Symposium on Plant and UVB Radiat., 2000 pp. 77-79.

  9. 細胞内抗酸化性を向上させる低線量放射線バイスタンダー効果 Invited International conference

    熊谷 純

    第73回ONSA先端科学研究会 第64回放射線科学研究会  2017.10.20  一般社団法人 大阪ニュークリアサイエンス協会

     More details

    Language:English   Presentation type:Oral presentation (general)  

    Venue:住友クラブ(大阪市西区江戸堀1-13-10)  

  10. J. Kumagai: Long-lived radicals and their biological effects in mammalian cells and rice cultivars as studied by ESR and ESEEM spectroscopy, Society of Royal Chemistry, University Catholique de Louvain, 2000, Belgium.

     More details

    Language:English   Presentation type:Oral presentation (invited, special)  

  11. J. Kumagai, T. Kumada, T. Miyazaki: Temperature effect on selective tunneling abstraction reaction by H atoms in neopentane-alkane mixtures at 4-100 K, 3rd Int. Conf. on Low Temp. Chem., edited by T. Miyazaki, 1999, pp. 27-28.

     More details

    Language:English   Presentation type:Oral presentation (invited, special)  

  12. J. Kumagai, T. Kumada, M. Watanabe, T. Miyazaki: Electron-spin-echo study of long-lived radicals which cause DNA mutation and cancer in mammalian cells, 3rd Int. Conf. on Low Temp. Chem., edited by T. Miyazaki, 1999, pp. 137-138.

     More details

    Language:English   Presentation type:Oral presentation (invited, special)  

  13. J. Kumagai, H. Katoh, T. Miyazaki, J. Hidema, T. Kumagai: Differences in the sensitivity to UVB radiation of two cultivars of rice (Oryza sativa L.) based on observation of long-lived radicals, COE-IGE Int. Symposium on Plant and UVB Radiat., 2000 pp. 77-79.

     More details

    Language:English   Presentation type:Oral presentation (invited, special)  

  14. J. Kumagai, H. Katoh, T. Miyazaki, J. Hidema, T. Kumagai: Differences in the sensitivity to UVB radiation of two cultivars of rice (Oryza sativa L.) based on observation of long-lived radicals, COE-IGE Int. Symposium on Plant and UVB Radiat., 2000 pp. 77-

     More details

    Language:English   Presentation type:Oral presentation (invited, special)  

  15. Radiation-Induced Bystander Effect of Normal, Cancer and Stem Cells as Studied by Long-Lived Radicals Invited

    Jun Kumagai, Akane Oohashi, Genro Kashino

    Hiroshima International Workshop on Circular Dichroism Spectroscopy 2017 -Application to Imaging Microscopy and Radiation Biology-  2017.2.28  Hiroshima Synchroton Radiation Center

     More details

    Language:English   Presentation type:Oral presentation (invited, special)  

    Venue:Hiroshima Synchroton Radiation Center  

▼display all

Research Project for Joint Research, Competitive Funding, etc. 4

  1. 低線量放射線影響の解明に寄与する放射線バイスタンダー効果研究

    2015.08 - 2017.03

    国内共同研究 

    菓子野元郎

      More details

    低線量放射線影響の解明に寄与する放射性バイスイスタンダー効果研究として,ヒトの幹細胞・正常細胞・がん細胞の培地移動放射線バイスタンダー効果を,レシピエント細胞中の長寿命ラジカルレベルから評価した.また,被曝ドナー細胞からの分泌因子について,サイトカインの網羅解析と,エクソソームの粒径分布の線量依存性から評価した.
     その結果,幹細胞・がん細胞が低線量(0.2 Gy)のγ線を被曝すると,未照射時と異なる粒径分布のエクソソームが放出され,それもしくは他のバイスタンダー因子を受けた正常細胞・がん細胞においては細胞内酸化度の指標となる長寿命ラジカルレベルが対照群と比較して20〜30%も下がった.一方,ドナーのがん細胞にp53遺伝子を発現させてある場合は,十分なレベル低下は見られなかった.これらの結果はレシピエント細胞中がp53遺伝子の発現していないドナーから放出されたバイスタンダー因子を取り込んで抗酸化機能遺伝子の発現が亢進し,グルタチオンを代表とする細胞内抗酸化剤が増えることによって,定常時にミトコンドリアから漏れ出てくる電子によって生成するO2-が消去され,長寿命ラジカルレベルも下がったものと考えられる.ハムスター卵巣細胞(CHO)においては,培地移動実験において0.2 GyではレシピエントのCHO細胞中の長寿命ラジカルレベルの変化は見られず,4 Gyで20%ものレベル上昇が見られたのに対し,ヒトの細胞においては0.2 Gyで逆に最も顕著なレベル低下が見られるという,とても対照的な結果が得られた.ヒトの細胞においては,低線量被曝で誘導されたバイスタンダー因子を取り込むことによって,正常細胞でもがん細胞でも放射線抵抗性を獲得することがわかった一方で,ドナー細胞がp53遺伝子を発現している場合はそれが押さえられる可能性も示唆された.p53発現細胞を用いた実験は低線量でのデータが不足しているため,今後,実験を行ってその真偽を確認する必要がある.
     C6(ラットグリオーマ細胞)とRNB(ラットアストロサイト(非腫瘍)細胞)をγ線照射サイトカインアッセイキットにより,培養上清中の24種のサイトカイン量を網羅解析したところ,C6細胞においてIL-6のみが誘導されることを見出した.IL-6を照射C6細胞に処理すると,細胞内酸化度・ミトコンドリア活性酸素レベルを低減し,生存率も向上させたが,RNB細胞ではそのような効果は確認できなかった.IL-6は放射線で誘導され,放射線抵抗性を誘導するバイスタンダー因子となりうるが,どの細胞に対しても放射線抵抗性を誘導するわけではなかった

  2. タングステンメッシュを用いた放射線遮蔽材の研究

    2012.01 - Now

    国内共同研究 

      More details

    タングステンメッシュやタングステン素材を用いた放射線遮蔽材の研究

  3. 原子力安全研究推進事業 低線量・低線量率放射線による発がん機構に関する研究

    2010.10 - 2016.03

    国内共同研究 

  4. 放射線生物学で意味のある線量域における突然変異誘発長寿命ラジカルの直接観測

    2006

KAKENHI (Grants-in-Aid for Scientific Research) 2

  1. 遅発性長寿命ラジカルは遺伝的不安定性・バイスタンダー効果の鍵物質になりうるか? 

    2008

    科学研究費補助金  萌芽研究,課題番号:20651013

    熊谷 純

      More details

    Authorship:Principal investigator 

  2. 遅発性長寿命ラジカルは遺伝的不安定性・バイスタンダー効果の鍵物質になりうるか?

    2008

    科学研究費助成事業  萌芽研究,課題番号:20651013

    熊谷 純

      More details

    Authorship:Principal investigator  Grant type:Competitive

 

Teaching Experience (On-campus) 3

  1. 分析化学

    2014

  2. 分析化学

    2013

  3. 分析化学序論

    2013

Teaching Experience (Off-campus) 3

  1. 分子素材工学特別講義IV

    2013.4 - Now Mie University)

  2. 複合材料学特論

    2013.4 - 2014.3 Yamagata University)

  3. 放射線と生命

    2008.4 - 2009.3 Kobe University)

 

Social Contribution 1

  1. 理科を楽しむ

    Lecturer, Demonstrator

    三重県菰野町立朝上小学校  2010 - Now

     More details

    Audience: Schoolchildren

    放射線化学反応を目で見て確認したり,液体窒素を使った体験実験を行い,それを感想文にまとめて,理科を楽しむ体験型授業を行っている.