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Journal Articles

Dense radical formation in L-alanine-3,3,3-d3 and L-alanine-d4 by 1.5 keV soft X-ray irradiation

Nakagawa, Seiko*; Oka, Toshitaka; Fujii, Kentaro*; Yokoya, Akinari*

Radiation Physics and Chemistry, 192, p.109884_1 - 109884_5, 2022/03

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$$^{-6}$$ relative to that by $$gamma$$-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.

Journal Articles

Sequence-dependent hydration water dynamics of dodecameric DNA

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$$_{2}$$O/D$$_{2}$$O contrast for two DNA dodecamers, 5'CGCG$$underline{rm AATT}$$CGCG'3 and 5'CGCG$$underline{rm TTAA}$$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.

Journal Articles

Inelastic and quasi-elastic neutron scattering spectrometers in J-PARC

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:21 Percentile:80.69(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.

Journal Articles

LET and dose rate effect on radiation-induced copolymerization in physical gel

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:21.72(Instruments & Instrumentation)

N$$_{2}$$-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.

Journal Articles

Local dynamics coupled to hydration water determines DNA-sequence-dependent deformability

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:7 Percentile:50.1(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.

Journal Articles

Solvent effect on copolymerization of maleimide with styrene induced by irradiation of ion and electron beams

Nakagawa, Seiko*; Taguchi, Mitsumasa; Kimura, Atsushi

Radiation Physics and Chemistry, 91, p.143 - 147, 2013/10

 Times Cited Count:3 Percentile:29.69(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).

Journal Articles

LET and dose rate effect on radiation-induced copolymerization of maleimide with styrene in 2-propanol solution

Nakagawa, Seiko*; Taguchi, Mitsumasa; Kimura, Atsushi

Radiation Physics and Chemistry, 80(11), p.1199 - 1202, 2011/11

 Times Cited Count:5 Percentile:42.62(Chemistry, Physical)

N$$_{2}$$-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.

Journal Articles

Degradation of hydroxymaleimide in 2-propanol by irradiation of energetic heavy ions, 2; N$$_{2}$$-saturated system

Nakagawa, Seiko*; Taguchi, Mitsumasa; Hirota, Koichi; Murakami, Takeshi*

Radiation Physics and Chemistry, 79(8), p.890 - 893, 2010/08

 Times Cited Count:3 Percentile:26.36(Chemistry, Physical)

Hydroxymaleimide was irradiated in N$$_{2}$$-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 $$gamma$$-irradiation.

Journal Articles

Degradation of hydroxymaleimide in 2-propanol by irradiation of energetic heavy ions, 1; Air-saturated system

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:31.93(Chemistry, Physical)

Hydroxymaleimide was irradiated in air-saturated 2-propanol solution by high-energy heavy ions. The differential ${it G}$-values of the degradation of hydroxymaleimide was smaller than the ${it G}$-value obtained by $$gamma$$-irradiation, and decreased with increasing LET value for the same kind of ions. The fitting curve of the differential ${it G}$-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.

Journal Articles

LET effect on irradiation of hydroxymaleimide in alcohol solution

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

Journal Articles

LET effect on irradiation of hydroxy imide compounds in alcohol solution

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

Oral presentation

LET effect on irradiation of hydroxymaleimide in 2-propanol, 1

Nakagawa, Seiko*; Taguchi, Mitsumasa; Kojima, Takuji

no journal, , 

no abstracts in English

Oral presentation

LET effect on irradiation of hydroxy imide compounds in alcohol solutions

Nakagawa, Seiko*; Ota, Nobuaki*; Taguchi, Mitsumasa; Kojima, Takuji

no journal, , 

no abstracts in English

Oral presentation

LET effect on radiation of hydroxymaleimide in 2-propanol

Nakagawa, Seiko*; Taguchi, Mitsumasa; Kojima, Takuji

no journal, , 

no abstracts in English

Oral presentation

LET effect of hydroxy imide compounds in alcohol solution

Nakagawa, Seiko*; Ota, Nobuaki*; Taguchi, Mitsumasa

no journal, , 

no abstracts in English

Oral presentation

Degradation of hydroxymaleimide in 2-propanol by irradiation of $$gamma$$-ray and energetic heavy ions

Nakagawa, Seiko*; Taguchi, Mitsumasa; Ota, Nobuaki*; Hirota, Koichi

no journal, , 

no abstracts in English

Oral presentation

LET effect on radiation of hydroxymaleimide in 2-propanol, 2

Nakagawa, Seiko*; Ota, Nobuaki*; Hirota, Koichi; Taguchi, Mitsumasa

no journal, , 

no abstracts in English

Oral presentation

ESR spectra of N$$^{4+}$$ or P$$^{4+}$$ doped polyaniline

Ota, 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$$^{4+}$$ or P$$^{4+}$$ 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$$^{4+}$$ was less than 2$$times$$10$$^{12}$$ions/cm$$^{2}$$ and that of P$$^{4+}$$ was more than 6$$times$$10$$^{12}$$ions/cm$$^{2}$$.

Oral presentation

Degradation of hydroxymaleimide in N$$_{2}$$-saturated 2-propanol by irradiation of energetic ions

Nakagawa, Seiko*; Taguchi, Mitsumasa; Ota, Nobuaki*; Hirota, Koichi

no journal, , 

no abstracts in English

Oral presentation

LET effect on irradiation of hydroxymaleimide in N2-saturated 2-propanol

Nakagawa, Seiko*; Ota, Nobuaki*; Taguchi, Mitsumasa; Hirota, Koichi

no journal, , 

no abstracts in English

27 (Records 1-20 displayed on this page)