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Maurer, C.*; Galmarini, S.*; Solazzo, E.*; Ku
mierczyk-Michulec, J.*; Bar
, J.*; Kalinowski, M.*; Schoeppner, M.*; Bourgouin, P.*; Crawford, A.*; Stein, A.*; et al.
Journal of Environmental Radioactivity, 255, p.106968_1 - 106968_27, 2022/12
Times Cited Count：2 Percentile：14.8(Environmental Sciences)After performing multi-model exercises in 2015 and 2016, a comprehensive Xe-133 atmospheric transport modeling challenge was organized in 2019. For evaluation measured samples for the same time frame were gathered from four International Monitoring System stations located in Europe and North America with overall considerable influence of IRE and/or CNL emissions. As a lesion learnt from the 2nd ATM-Challenge participants were prompted to work with controlled and harmonized model set ups to make runs more comparable, but also to increase diversity. Effects of transport errors, not properly characterized remaining emitters and long IMS sampling times (12 to 24 hours) undoubtedly interfere with the effect of high-quality IRE and CNL stack data. An ensemble based on a few arbitrary submissions is good enough to forecast the Xe-133 background at the stations investigated. The effective ensemble size is below five.
Maurer, C.*; Bar, J.*; Kusmierczyk-Michulec, J.*; Crawford, A.*; Eslinger, P. W.*; Seibert, P.*; Orr, B.*; Philipp, A.*; Ross, O.*; Generoso, S.*; et al.
Journal of Environmental Radioactivity, 192, p.667 - 686, 2018/12
Times Cited Count：25 Percentile：65.58(Environmental Sciences)It is very important to understand the impact for CTBT stations caused by radioxenon emitted from medical isotope production facilities for detection of underground nuclear tests. Predictions of the impact on six CTBT radionuclide stations in the Southern Hemisphere of radioxenon emitted from the medical isotope production facility in Australia were carried out by participants from ten nations using ATM (Atmospheric Transport Modeling) based on the emission data of radioxenon from this facility, as part of study on impact of radioxenon emitted from medical isotope production facilities on CTBT radionuclide stations.
Ikeda, Takashi; Hou, Z.*; Chai, G.-L.*; Terakura, Kiyoyuki*
Hyomen Kagaku, 36(7), p.345 - 350, 2015/07
Carbon alloy catalysts (CACs) are one of promising candidates for platinum-substitute cathode catalysts for polymer electrolyte fuel cells. We have investigated possible mechanisms of oxygen reduction reactions (ORRs) for CACs via first-principles-based molecular dynamics simulations. In this contribution, we review possible ORRs at likely catalytic sites of CACs suggested from our simulations.
Chai, G.-L.*; Hou, Z.*; Shu, D.-J.*; Ikeda, Takashi; Terakura, Kiyoyuki*
Journal of the American Chemical Society, 136(39), p.13629 - 13640, 2014/10
Times Cited Count：252 Percentile：97.75(Chemistry, Multidisciplinary)Carbon alloy catalysts (CACs) are promising catalysts for oxygen reduction reaction (ORR) to substitute Pt. However, despite extensive studies on CACs the reaction sites and mechanisms for ORR are still in controversy. Herein, we present rather general consideration on possible ORR mechanisms for various structures in nitrogen doped CACs based on the first principles calculations. Our study indicates that only a particular structure of a nitrogen pair doped Stone-Wales defect provides a good active site. The ORR activity of this structure can be tuned by the curvature around the active site, which makes its limiting potential approaching the maximum limiting potential (0.80 V) in the volcano plot for the ORR activity of CACs. The calculated results can be compared with the recent experimental ones of the half wave potential for CAC systems that range from 0.60 V to 0.80 V in the reversible-hydrogen-electrode scale.
Ikeda, Takashi; Hou, Z.*; Chai, G.-L.*; Terakura, Kiyoyuki*
Journal of Physical Chemistry C, 118(31), p.17616 - 17625, 2014/08
Times Cited Count：50 Percentile：80.77(Chemistry, Physical)N-doped carbon-based nanomaterials are attracting a great interest as promising Pt-free electrode catalysts for polymer electrolyte fuel cells (PEFCs). In this computational study, we demonstrate that N-doped graphene edges can exhibit enhanced catalytic activity toward oxygen reduction reactions by controlling their electron-donating and -withdrawing abilities, and basicity, resulting in higher selectivity of 4e
reduction via inner and outer sphere electron transfer at edges in acidic conditions, respectively. Our simulations also show that 2e reduction occurs selectively in the presence of pyridinic N next to carbonyl O at zigzag edges. This study thus rationalizes the roles of doped N in graphenelike materials for oxygen reduction reactions.
Hou, Z.*; Shu, D.-J.*; Chai, G.-L.*; Ikeda, Takashi; Terakura, Kiyoyuki*
Journal of Physical Chemistry C, 118(34), p.19795 - 19805, 2014/08
Times Cited Count：11 Percentile：35.81(Chemistry, Physical)In most of the N-doped graphene which attracts strong attention in the context of precious-metal free catalysts and nanoelectronics, the oxygen content is generally higher than or at least comparable to the nitrogen content. We perform density functional theory calculations to study the interplay of oxidized monovacancies and the nitrogen doping, motivated by the fact that MV is more frequently observed and more chemically active than divacancy and Stone-Wales defect. We determine the phase diagrams of un-doped and nitrogen-doped oxidized MVs as a function of temperature and partial pressure of O
and H gases. The modification of the electronic structure of MV by oxidation and N doping is studied. Our results show that the ether group is a common component in stable configurations of oxidized MVs. Most of the stable configurations of oxidized MVs do not induce any carriers.
Shi, W.-Q.*; Fu, H.-Y.*; Bounds, P. L.*; Muroya, Yusa*; Lin, M.; Katsumura, Yosuke*; Zhao, Y.-L.*; Chai, Z.-F.*
Radiation Research, 176(1), p.128 - 133, 2011/07
Times Cited Count：3 Percentile：17.22(Biology)3-Nitrotyrosine (3-NT) has been reported as an important biomarker of oxidative stress and potential source of reactive oxygen species (ROSs). In this work, the UV-visible absorption spectra of the transients formed by hydrated electron (e
) reacting with 3-NT and its derivatives were investigated, the spectra showed many characteristics of aromatic nitro anion radical. The reaction rate constants of e reacting with 3-NT, N-acetyl-3-nitrotyrosine ethyl ester (NANTE) and nitrotyrosine-containing peptide Gly-nitroTyr-Gly at neutral pH were determined, respectively, which were almost two orders of magnitude higher than that of tyrosine and tyrosine-containing peptides. The pH-dependence of e decay rate constants in presence of 3-NT was also studied.
Ueda, Masashi; Chai, L.*; Meshii, Toshiyuki*; Miyahara, Shinya; Okamoto, Hisahiko
no journal, ,
To estimate feasibility of the acoustic leak detection system for the steam generators of FBR, axis-symmetrical finite element code was developed and accoustic propagation befavior in the steam generator was evaluated by this code.
Ikeda, Takashi; Hou, Z.*; Chai, G.-L.*; Terakura, Kiyoyuki*
no journal, ,
no abstracts in English
