Changes in molecular conformation and electronic structure of DNA under C ions based on first-principles calculations

Sekikawa, Takuya; Matsuya, Yusuke; Hwang, B.*; Ishizaka, Masato*; Kawai, Hiroyuki*; Ono, Yoshiaki*; Sato, Tatsuhiko; Kai, Takeshi

Nuclear Instruments and Methods in Physics Research B, 548, p.165231_1 - 165231_6, 2024/03

https://doi.org/10.1016/j.nimb.2023.165231

One of the main causes of radiation effects on the human body is thought to be damage to DNA, which carries genetic information. However, it is not fully understood what kind of molecular structural changes DNA undergoes upon radiation damage. Since it has been reported that various types of DNA damage are formed when DNA is irradiated, our group has investigated the relationship between DNA damage and various patterns of radiation-induced ionization induced by radiation. Although we have so far analyzed DNA damage in a simple system using a rigid body model of DNA, more detailed calculations are required to analyze the molecular structural changes in DNA, which are considered to be important in considering the effects on the human body. In this study, we attempted to clarify the molecular conformational changes of DNA using OpenMX, a first-principles calculation software that can discuss electronic states based on molecular structures. Specifically, we calculated the most stable structure, band dispersion, and wave function of DNA under the assumption that one and two electrons are ionized by various radiation. In the presentation, we will discuss the relationship between the energy dependence of each incident radiation type and the molecular conformational change of DNA. In addition, the radiation-induced changes in the basic physical properties of DNA (corresponding to the initial stage of DNA damage) will be discussed from the viewpoints of both radiation physics and solid state physics.

Local electronic structure of interstitial hydrogen in MgH inferred from muon study

Kadono, Ryosuke*; Hiraishi, Masatoshi*; Okabe, Hirotaka*; Koda, Akihiro*; Ito, Takashi

Journal of Physics; Condensed Matter, 35(28), p.285503_1 - 285503_13, 2023/07

https://doi.org/10.1088/1361-648X/acccc7

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

https://doi.org/10.1080/00223131.2022.2038301

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Calculation of shutdown gamma distribution in the high temperature engineering test reactor

Ho, H. Q.; Ishii, Toshiaki; Nagasumi, Satoru; Ono, Masato; Shimazaki, Yosuke; Ishitsuka, Etsuo; Goto, Minoru; Simanullang, I. L.*; Fujimoto, Nozomu*; Iigaki, Kazuhiko

Nuclear Engineering and Design, 396, p.111913_1 - 111913_9, 2022/09

https://doi.org/10.1016/j.nucengdes.2022.111913

Structural phase transition in cobalt oxyfluoride CoSbOF observed by high-resolution synchrotron and neutron diffraction

Shimono, Seiya*; Ishibashi, Hiroki*; Nagayoshi, Yusuke*; Ikeno, Hidekazu*; Kawaguchi, Shogo*; Hagihara, Masato; Torii, Shuki*; Kamiyama, Takashi*; Ichihashi, Katsuya*; Nishihara, Sadafumi*; et al.

Journal of Physics and Chemistry of Solids, 163, p.110568_1 - 110568_7, 2022/04

https://doi.org/10.1016/j.jpcs.2021.110568

Seismic classification of high temperature engineering test reactor

Ono, Masato; Shimizu, Atsushi; Ohashi, Hirofumi; Hamamoto, Shimpei; Inoi, Hiroyuki; Tokuhara, Kazumi*; Nomoto, Yasunobu*; Shimazaki, Yosuke; Iigaki, Kazuhiko; Shinozaki, Masayuki

Nuclear Engineering and Design, 386, p.111585_1 - 111585_9, 2022/01

https://doi.org/10.1016/j.nucengdes.2021.111585

In the late 1980s during the design stage, the seismic classification of the high temperature engineering test reactor (HTTR) was formulated. Owing to the lack of operation experiences of the HTTR to sufficiently understand the safety characteristics of high temperature gas cooled reactors (HTGR) at that time, the seismic classification of commercial light water reactors (LWR) was applied to HTTR. However, the subsequent operation experiences and test results using HTTR made it clear that the seismic classification of commercial LWR was somewhat too conservative for the HTGR. As a result, Class S facilities were downgraded compared to the commercial LWR. Moreover, the validity of the new seismic classification is confirmed. In June 2020, the Nuclear Regulatory Authority approved that the result of the seismic classification conformed to the standard rules of the reactor installation change.

Impact assessment for internal flooding in HTTR (High temperature engineering test reactor)

Tochio, Daisuke; Nagasumi, Satoru; Inoi, Hiroyuki; Hamamoto, Shimpei; Ono, Masato; Kobayashi, Shoichi; Uesaka, Takahiro; Watanabe, Shuji; Saito, Kenji

JAEA-Technology 2021-014, 80 Pages, 2021/09

JAEA-Technology-2021-014.pdf:5.87MB

In response to the new regulatory standards established in response to the accident at TEPCO's Fukushima Daiichi Nuclear Power Station in March 2011, measures and impact assessments related to internal flooding at HTTR were carried out. In assessing the impact, considering the characteristics of the high-temperature gas-cooled reactor, flooding due to assumed damage to piping and equipment, flooding due to water discharge from the system installed to prevent the spread of fire, and flooding due to damage to piping and equipment due to an earthquake. The effects of submersion, flooding, and flooding due to steam were evaluated for each of them. The impact of the overflow of liquids containing radioactive materials outside the radiation-controlled area was also evaluated. As a result, it was confirmed that flooding generated at HTTR does not affect the safety function of the reactor facility by taking measures.

Morphological reproductive characteristics of testes and fertilization capacity of cryopreserved sperm after the Fukushima accident in raccoon ()

Komatsu, Kazuki*; Iwasaki, Tsugumi*; Murata, Kosuke*; Yamashiro, Hideaki*; Goh, V. S. T.*; Nakayama, Ryo*; Fujishima, Yohei*; Ono, Takumi*; Kino, Yasushi*; Shimizu, Yoshinaka*; et al.

Reproduction in Domestic Animals, 56(3), p.484 - 497, 2021/03

https://doi.org/10.1111/rda.13887

We have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long and continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of raccoons from the ex-evacuation zone of the FDNPP accident. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.

Analysis of the activities of the website "Question and Answer about radiation in Daily Life" after the accident at the Fukushima Daiichi Nuclear Power Station and some lessons learned from it; To pass on this experience to the future

Kono, Takahiko; Shimo, Michikuni*; Hayakawa, Hironobu*; Taniguchi, Kazufumi*; Tanaka, Masato*; Tanaka, Hitomi*; Onoue, Yosuke*; Nagaya, Hiroshi*; Torii, Hiroyuki*; Uno, Kazuko*

Hoken Butsuri (Internet), 55(4), p.226 - 238, 2020/12

https://doi.org/10.5453/jhps.55.226

After the accident at the Fukushima Daiichi Nuclear Power Station, artificial radionuclides such as radioactive cesium and iodine were released into the environment. It caused great anxiety not only in the vicinity of the Fukushima Daiichi Nuclear Power Station but also in other regions of Japan. Some members of the Japan Health Physics Society (JHPS) which is a leading academic society in Japan in the field of radiation protection volunteered to establish the website called "Question and Answer about radiation in Daily Life" just after the accident to reduce the anxiety of the residents about the health effects of radiation. After that, Committee of "Question and Answer about radiation in Daily Life" was established in August 2011 in JHPS, and this activity had been carried out under the responsibility of the society that answered with sincerity against questions from the public as specialists until February 2013. The number of questions on the website had gradually decreased as time passed; therefore, the Committee members decided to end these activities in February 2013. In this paper, following contents were shown; the activities of the Q&A website for about two years, the issues of the stance on our activities, the information related to the website activities and the analysis of Twitter data. Based on the experience and the knowledge obtained from these activities, the issues and experiences that can be utilized in the initial response to emergencies for radiation protection experts as well as other fields are presented.

Dynamic observation and theoretical analysis of initial O molecule adsorption on polar and -plane surfaces of GaN

Sumiya, Masatomo*; Sumita, Masato*; Asai, Yuya*; Tamura, Ryo*; Uedono, Akira*; Yoshigoe, Akitaka

Journal of Physical Chemistry C, 124(46), p.25282 - 25290, 2020/11

https://doi.org/10.1021/acs.jpcc.0c07151

The initial oxidation of different GaN surfaces [the polar Ga-face (+c) and N-face (-c) and the nonpolar (100) ()plane] under O molecular beam irradiation was studied by real-time synchrotron radiation X-ray photoelectron spectroscopy and DFT molecular dynamics calculation. The results predict that triplet O either dissociates or chemisorbs at the bridge position on the +c-surface, while on N-terminated -c-surface the O2 molecule only undergoes dissociative chemisorption. On the -GaN surface, although the dissociation of O is dominant, the bond length and angle were found to fluctuate from those of O molecules adsorbed on the polar surfaces. The computational model including both the surface spin and polarity of GaN is useful for understanding the interface between GaN and oxide layers in metal-oxide electronic.