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Nakagawa, Seiko*; Oka, Toshitaka; Fujii, Kentaro*; Yokoya, Akinari*
Radiation Physics and Chemistry, 192, p.109884_1 - 109884_5, 2022/03
Times Cited Count：2 Percentile：53.91(Chemistry, Physical)Radicals produced in crystalline L-alanine-3,3,3-d3 and L-alanine-d4 were observed by the electron spin resonance (ESR) technique during 1.5 keV soft X-ray irradiation. The line width of the ESR spectra obtained by the soft X-ray irradiation was 1.5 times wider than that of hard X-rays from a previous report, meaning a higher density of radicals. The efficiency of the radical yield by the soft X-ray irradiation was 10
relative to that by 
-irradiation. For the soft X-ray irradiation, many radicals will be lost by the efficient radical-radical recombination due to the higher density of the radicals, just as the high-LET irradiation by heavy ions. We concluded that the high LET nature of the lower energy photons leads to the dense radical formation in the crystalline alanine powder.
Nakagawa, Hiroshi; Yonetani, Yoshiteru*; Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Kataoka, Mikio*; Kono, Hidetoshi*
JPS Conference Proceedings (Internet), 33, p.011101_1 - 011101_6, 2021/03
Hydration water dynamics were measured by quasi-elastic neutron scattering with Hn
O/DO contrast for two DNA dodecamers, 5'CGCG
CGCG'3 and 5'CGCG
CGCG'3, which have been computationally shown to be structurally rigid and flexible, respectively. The dynamical transitions of the hydration water as well as DNA were observed for both sequences at approximately 240 K. Above the transition temperature, the mean square displacements of the hydration water for the rigid sequence were smaller than those for the flexible one. Furthermore, the relaxation time of the hydration water was longer in the rigid DNA than in the flexible DNA. We suggest that hydration water dynamics on the picosecond timescale are associated with sequence-dependent deformability of DNA.
Seto, Hideki; Ito, Shinichi; Yokoo, Tetsuya*; Endo, Hitoshi*; Nakajima, Kenji; Shibata, Kaoru; Kajimoto, Ryoichi; Kawamura, Seiko; Nakamura, Mitsutaka; Kawakita, Yukinobu; et al.
Biochimica et Biophysica Acta; General Subjects, 1861(1), p.3651 - 3660, 2017/01
Times Cited Count：32 Percentile：80.67(Biochemistry & Molecular Biology)J-PARC, Japan Proton Accelerator Research Complex provides short pulse proton beam at a repetition rate 25 Hz and the maximum power is expected to be 1 MW. Materials and Life Science Experimental Facility (MLF) has 23 neutron beam ports and 21 instruments have already been operated or under construction / commissioning. There are 6 inelastic / quasi-elastic neutron scattering spectrometers and the complementary use of these spectrometers will open new insight for life science.
Nakagawa, Seiko*; Taguchi, Mitsumasa; Kimura, Atsushi; Nagasawa, Naotsugu; Hiroki, Akihiro
Nuclear Instruments and Methods in Physics Research B, 334, p.64 - 68, 2014/09
Times Cited Count：2 Percentile：19.23(Instruments & Instrumentation)N-saturated 2-propanol solutions containing styrene and maleimide were gelled by the addition of hydroxypropylcellulose and irradiated by proton, He and C-ion beams. The trend in the dose rate and LET effects on the yield and molecular weight distribution of the polymer produced in the gel was almost the same in the solution. On the contrary, the dose rate effect in the gel was higher than that in the solution. This effect was accelerated for irradiations by proton as well as heavier ion with a higher LET value.
Nakagawa, Hiroshi; Yonetani, Yoshiteru; Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Inamura, Yasuhiro; Kataoka, Mikio; Kono, Hidetoshi
Physical Review E, 90(2), p.022723_1 - 022723_11, 2014/08
Times Cited Count：10 Percentile：55.34(Physics, Fluids & Plasmas)Molecular dynamics (MD) simulations and Quasi-Elastic Neutron Scattering (QENS) experiments were conducted on hydrated two DNA dodecamers with distinct deformability; 5'CGCGAATTCGCG3' and 5'CGCGTTAACGCG3'. The former is known to be rigid and the latter to be flexible. The mean-square displacements (MSDs) of DNA dodecamers exhibit so-called dynamical transition around 200-240 K for both sequences. To investigate the DNA sequence dependent dynamics, the dynamics of DNA and hydration water above the transition temperature were examined using both MD simulations and QENS experiments. The fluctuation amplitude of the AATT central tetramer is smaller, and its relaxation time is longer, than that observed in TTAA, suggesting that the AT step is kinetically more stable than TA. The sequence-dependent local base pair step dynamics correlate with the kinetics of breaking the hydrogen bond between DNA and hydration water. The sequence dependent DNA base pair step fluctuations appear above the dynamical transition temperature. Together with these results, we conclude that DNA deformability is related to the local dynamics of base pair step, themselves coupled to hydration water in the minor groove.
Nakagawa, Seiko*; Taguchi, Mitsumasa; Kimura, Atsushi
Radiation Physics and Chemistry, 91, p.143 - 147, 2013/10
Times Cited Count：3 Percentile：25.73(Chemistry, Physical)The radiation-induced polymerization of styrene with maleimide was studied in methanol, ethanol, and 2-propanol solutions by irradiation of electrons and C-ions. Co-polymer of styrene and maleimide was produced in each alcohol by radiation polymerization which induced the solvent radicals. The yields of the co-polymer for irradiation of the electrons and C-ions were 2.45 and 1.85 mg/mL/kGyin methanol, 4.41 and 3.16 mg/mL/kGy in ethanol, and 4.77 and 3.67 mg/mL/kGy in 2-propanol, respectively. Because the reactivity of the solvent radical with monomers (styrene and maleimide) was considered to increase in order of methanol, ethanol, and 2-propanol. The yield of the co-polymer for irradiation of C-ions (High-LET radiation, 600 eV/nm) was lower than that of electrons (Low-LET radiation, 0.2 eV/nm).
Nakagawa, Seiko*; Taguchi, Mitsumasa; Kimura, Atsushi
Radiation Physics and Chemistry, 80(11), p.1199 - 1202, 2011/11
Times Cited Count：6 Percentile：44.28(Chemistry, Physical)N-saturated 2-propanol solutions containing styrene and maleimide were irradiated by electron, proton, He and C-ion beams. The styrene-maleimide copolymer was produced by radical polymerization induced during irradiation. The effects of the radical distribution, which depends on the LET or dose rate, on the molecular weight and the polymer yield were discussed. Both the molecular weight and the polymer yield increased by the decreasing dose rate. These effects increased by irradiation using heavier ions. The polymer yield decreased with the increasing LET value. On the other hand, irradiation at a higher LET value and lower dose rate will produce a polymer with a higher molecular weight. The distribution of radicals in time and space will have an influence on both the molecular weight and the polymer yield.
-saturated systemNakagawa, Seiko*; Taguchi, Mitsumasa; Hirota, Koichi; Murakami, Takeshi*
Radiation Physics and Chemistry, 79(8), p.890 - 893, 2010/08
Times Cited Count：3 Percentile：24.08(Chemistry, Physical)Hydroxymaleimide was irradiated in N-saturated 2-propanol solutions by high-energy heavy ions over a wide range of LET values. The differential G-values of the degradation of hydroxymaleimide by irradiation with the heavier ions were lower than those of the lighter ions for the same LET value. It was opposite result obtained in the air-saturated system. The degradation efficiency was 1.5 times higher, when the dose rate was 1/10 times lower. When irradiated at an LET value lower than 8 eV/nm, the G-values converged to a value less than that obtained by -irradiation.
Nakagawa, Seiko*; Taguchi, Mitsumasa; Ota, Nobuaki*; Hirota, Koichi
Radiation Physics and Chemistry, 77(10-12), p.1230 - 1232, 2008/10
Times Cited Count：4 Percentile：29.49(Chemistry, Physical)Hydroxymaleimide was irradiated in air-saturated 2-propanol solution by high-energy heavy ions. The differential 
-values of the degradation of hydroxymaleimide was smaller than the -value obtained by -irradiation, and decreased with increasing LET value for the same kind of ions. The fitting curve of the differential -values obtained for He ion is shifted from that for heavier ions. The irradiation effects of the kind and LET value of ions were observed on the degradation of hydroxymaleimide.
Nakagawa, Seiko*; Ota, Nobuaki*; Taguchi, Mitsumasa; Hirota, Koichi
JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 159, 2008/03
no abstracts in English
Nakagawa, Seiko*; Ota, Nobuaki*; Taguchi, Mitsumasa; Kojima, Takuji
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 142, 2007/02
no abstracts in English
Nakagawa, Seiko*; Taguchi, Mitsumasa; Kojima, Takuji
no journal, ,
no abstracts in English
Nakagawa, Seiko*; Ota, Nobuaki*; Taguchi, Mitsumasa; Kojima, Takuji
no journal, ,
no abstracts in English
Nakagawa, Seiko*; Taguchi, Mitsumasa; Kojima, Takuji
no journal, ,
no abstracts in English
Nakagawa, Seiko*; Ota, Nobuaki*; Taguchi, Mitsumasa
no journal, ,
no abstracts in English
-ray and energetic heavy ionsNakagawa, Seiko*; Taguchi, Mitsumasa; Ota, Nobuaki*; Hirota, Koichi
no journal, ,
no abstracts in English
Nakagawa, Seiko*; Ota, Nobuaki*; Hirota, Koichi; Taguchi, Mitsumasa
no journal, ,
no abstracts in English
or P doped polyanilineOta, Nobuaki*; Nakagawa, Seiko*; Nishiyama, Fumitaka*; Morishita, Norio; Oshima, Takeshi
no journal, ,
A bulk with 0.5-1 mm thickness of polyaniline was irradiated by the 3MV Tandem accelerator at the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) facility. ESR spectra of N or P doped polyaniline were measured at 77 K. A broad peak of polyaniline radical was observed. Except for polyaniline radical, new signals were also appeared when the fluence of doped N was less than 2
10
ions/cm
and that of P was more than 610ions/cm.
-saturated 2-propanol by irradiation of energetic ionsNakagawa, Seiko*; Taguchi, Mitsumasa; Ota, Nobuaki*; Hirota, Koichi
no journal, ,
no abstracts in English
Nakagawa, Seiko*; Ota, Nobuaki*; Taguchi, Mitsumasa; Hirota, Koichi
no journal, ,
no abstracts in English
