Faculty Profiles - KUMAGAI, Jun

Papers - KUMAGAI, Jun

Division display 1 - 20 of about 74 ／ All the affair displays >>

Fundermentals of interactions between ionizing radiation and matter Invited

Jun Kumagai

Chemical Industry Vol. 74 ( 2 ) page： 73 - 84 2023.2

Highly Active Rutile TiO2 for Photocatalysis under Violet Light Irradiation at 405 nm Reviewed

Fumiaki Amano, Akira Yamamoto and Jun Kumagai

Catalysts Vol. 12 page： 1079-1 - 1079-12 2022.9

A π–Cu(II)−π Complex as an Extremely Active Catalyst for Enantioselective α-Halogenation of N-Acyl-3,5-dimethylpyrazoles Reviewed International coauthorship

Kazuki Nishimura, Yanzhao Wang, Yoshihiro Ogura, Jun Kumagai, and Kazuaki Ishihara

ACS Catalysis Vol. 12 page： 1012 - 1017 2022.1

Stabilization of radical active species in a MOF nanospace to exploit unique reaction pathways Reviewed International coauthorship

Harada, Yuki, Kusaka, Shinpei, Nakajo, Toshinobu, Kumagai, Jun, Kim, Cho Rong, Shim, Joo Young, Hori, Akihiro, Ma, Yunsheng, Matsuda, Ryotaro

Chemical Communications Vol. 57 page： 12115 - 12118 2021.11

Triplet Carbene with Highly Enhanced Thermal Stability in the Nanospace of a Metal–Organic Framework Reviewed

Toshinobu Nakajo, Jun Kumagai, Shinpei Kusaka, Akihiro Hori, Yuh Hijikata, Jenny Pirillo, Yunsheng Ma, and Ryotaro Matsuda

Journal of the American Chemical Society Vol. 143 ( 21 ) page： 8129 - 8136 2021.6

Perspective on the Biological Mechanisms of Radiation-induced both Bystander and Rescue effects Invited Reviewed

Genro Kashino, Jun Kumagai, Kentaro Ariyoshi, Mitsuaki Ojima

Vol. 56 ( 1 ) page： 19 - 39 2021.4

O-17-ESR Evidence for Zeolite Matrix Isolation of a Square Planar ZnO3 Ring Radical with C-2v Symmetry Reviewed

Oda, Oda, Akira; Kumagai, Jun; Sawabe, Kyoichi; Ohkubo, Takahiro ; Kuroda, Yasushige; Satsuma, Atsushi

JOURNAL OF PHYSICAL CHEMISTRY C Vol. 125 ( 9 ) page： 5136 - 5145 2021.3

A low-temperature oxyl transfer to carbon monoxide from the Zn-II-oxyl site in a zeolite catalyst Reviewed

Oda, Akira; Kumagai, Jun; Ohkubo, Takahiro; Kuroda, Yasushige

INORGANIC CHEMISTRY FRONTIERS Vol. 8 ( 2 ) page： 319 - 328 2021.1

Effects of the amount of Au nanoparticles on the visible light response of TiO<sub>2</sub> photocatalysts International journal

Yoshida, T; Misu, Y; Yamamoto, M; Tanabe, T; Kumagai, J; Ogawa, S; Yagi, S

CATALYSIS TODAY Vol. 352 page： 34 - 38 2020.8

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

We have succeeded to prepare Au nanopareticle deposited TiO2 photocatalysts (Au/TiO2) with control of Au nanoparticle size to be around 8 nm and variation of number density using a colloid photodepostion method. The prepared Au/TiO2 exhibits activity on decomposition (oxidation) of formic acid by thermally activated and photo-activated catalytic reactions. The thermally activated catalytic decomposition gradually increases with increasing the number density of deposited Au NPs and saturated, suggesting that the decomposition occurs on Au NPs surface and/or near the interface of TiO2 and Au NPs. On the other hand, the photocatalytic decomposition is significantly improved with rather small number density deposition of Au NPs and disappeared with high number density deposition. ESR measurements of Au/TiO2 in the surrounding similar to the photocatalytic decomposition suggests that electrons excited by plasmon resonance absorption in the Au NPs transfer to TiO2 to promote the decomposition. However, high number density deposition enhances electron capture by neighboring Au NPs and reduces the photocatalytic activity. Thus there should be the optimum number density of Au NPs on TiO2 for photocatalytic decomposition of formic acid.

DOI： 10.1016/j.cattod.2019.12.035

Web of Science

Scopus

Exploiting single-electron transfer in Lewis pairs for catalytic bond-forming reactions International journal

Aramaki, Y; Imaizumi, N; Hotta, M; Kumagai, J; Ooi, T

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

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

A single-electron transfer (SET) between tris(pentafluorophenyl)borane (B(C6F5)3) andN,N-dialkylanilines is reported, which is operativeviathe formation of an electron donor-acceptor (EDA) complex involving π-orbital interactions as a key intermediate under dark conditions or visible-light irradiation depending on the structure of the aniline derivatives. This inherent SET in the Lewis pairs initiates the generation of the corresponding α-aminoalkyl radicals and their additions to electron-deficient olefins, revealing the ability of B(C6F5)3to act as an effective one-electron redox catalyst.

DOI： 10.1039/d0sc01159b

Web of Science

Scopus

PubMed

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

Fundamental study of radiosensitization targeting cancer cell environmental factors

Kashino Genro, Kumagai Jun

CANCER SCIENCE Vol. 109 page： 751-751 2018.1

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

Jun Kumagai

RADIOISOTOPES Vol. 66 page： 489-496 2017.10

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

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

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

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

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

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

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

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

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

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

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

　 PREV - NEXT 　

<KUMAGAI, Jun>

Papers - KUMAGAI, Jun