start-ver=1.4
cd-journal=joma
no-vol=965
cd-vols=
no-issue=1
article-no=
start-page=91
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2024
dt-pub=20240410
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Supernova Burst and Diffuse Supernova Neutrino Background Simulator for Water Cherenkov Detectors
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=If a Galactic core-collapse supernova explosion occurs in the future, it will be critical to rapidly alert the community to the direction of the supernova by utilizing neutrino signals in order to enable the initiation of follow-up optical observations. In addition, there is anticipation that observation of the diffuse supernova neutrino background will yield discoveries in the near future, given that experimental upper limits are approaching theoretical predictions. We have developed a new supernova event simulator for water Cherenkov neutrino detectors, such as the highly sensitive Super-Kamiokande. This simulator calculates the neutrino interaction in water for two simulation purposes, individual core-collapse supernova bursts and diffuse supernova neutrino background. Based on this simulator, we can evaluate the precision in determining the location of supernovae and estimate the expected number of events related to the diffuse supernova neutrino background in Super-Kamiokande. In this paper, we describe the basic structure of the simulator and its demonstration.
en-copyright=
kn-copyright=

en-aut-name=NakanishiFumi
en-aut-sei=Nakanishi
en-aut-mei=Fumi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=IzumiyamaShota
en-aut-sei=Izumiyama
en-aut-mei=Shota
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=HaradaMasayuki
en-aut-sei=Harada
en-aut-mei=Masayuki
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=KoshioYusuke
en-aut-sei=Koshio
en-aut-mei=Yusuke
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

affil-num=1
en-affil=Department of Physics, Okayama University
kn-affil=

affil-num=2
en-affil=Department of Physics, Tokyo Institute of Technology
kn-affil=

affil-num=3
en-affil=Department of Physics, Okayama University
kn-affil=

affil-num=4
en-affil=Department of Physics, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=951
cd-vols=
no-issue=2
article-no=
start-page=L27
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2023
dt-pub=20230707
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Search for Astrophysical Electron Antineutrinos in Super-Kamiokande with 0.01% Gadolinium-loaded Water
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=We report the first search result for the flux of astrophysical electron antineutrinos for energies O(10) MeV in the gadolinium-loaded Super-Kamiokande (SK) detector. In 2020 June, gadolinium was introduced to the ultrapure water of the SK detector in order to detect neutrons more efficiently. In this new experimental phase, SK-Gd, we can search for electron antineutrinos via inverse beta decay with efficient background rejection thanks to the high efficiency of the neutron tagging technique. In this paper, we report the result for the initial stage of SK-Gd, during 2020 August 26, and 2022 June 1 with a 22.5 x 552 kton center dot day exposure at 0.01% Gd mass concentration. No significant excess over the expected background in the observed events is found for the neutrino energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90% confidence level. The limits and sensitivities are already comparable with the previous SK result with pure water (22.5 x 2970 kton center dot day) owing to the enhanced neutron tagging. Operation with Gd increased to 0.03% started in 2022 June.
en-copyright=
kn-copyright=

en-aut-name=HaradaM.
en-aut-sei=Harada
en-aut-mei=M.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

affil-num=1
en-affil=Department of Physics, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=6
cd-vols=
no-issue=4
article-no=
start-page=045006
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2022
dt-pub=20220425
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Resonance modes of a metal-semiconductor-metal multilayer mediated by electric charge
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Electromagnetic fields around metal-semiconductor-metal (MSM) multilayers with square island top layers were numerically simulated to elucidate the difference in physics between the circuit resonance and Fabry-Perot interference mediated by the surface plasmon polaritons (SPP). In the current study, the top and bottom metal layers were made of gold, and the intermediate semiconductor layer was a gallium antimony (GaSb). The lumped-element and Fabry-Perot interference models showed less accuracy when the island width of the MSM multilayer was comparatively smaller. Since the capacitor and SPP could not be supported between the top and bottom gold layers, the anti-reflection mode of the gold-GaSb bilayer mainly affected the absorptance. However, when the width of the island was sufficiently large, the time-lapse development of the electromagnetic fields at resonant wavelengths showed strong electric and magnetic responses relating to the circuit resonance. Simultaneously, the electric fields depicted the movement of the electric charge, which coupled to the short-range surface plasmon polariton (SRSP) existing at the thin GaSb layer sandwiched by two gold layers. The wavelength of the SRSP approximately corresponded to that of the Fabry-Perot interference. It was revealed that the lumped-element and Fabry-Perot interference models indicated the same resonant mode from two different perspectives in physics.
en-copyright=
kn-copyright=

en-aut-name=IsobeKazuma
en-aut-sei=Isobe
en-aut-mei=Kazuma
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=HanamuraKatsunori
en-aut-sei=Hanamura
en-aut-mei=Katsunori
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=Department of Advanced Mechanics, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=2
en-affil=School of Engineering, Department of Mechanical Engineering, Tokyo Institute of Technology
kn-affil=
en-keyword=resonance modes
kn-keyword=resonance modes
en-keyword=finite difference time domain method
kn-keyword=finite difference time domain method
en-keyword=metal-semiconductor-metal multilayer
kn-keyword=metal-semiconductor-metal multilayer
en-keyword=lumped-element model
kn-keyword=lumped-element model
en-keyword=Fabry-Perot interference
kn-keyword=Fabry-Perot interference
en-keyword=surface plasmon polariton
kn-keyword=surface plasmon polariton
en-keyword=electric charge
kn-keyword=electric charge
END

start-ver=1.4
cd-journal=joma
no-vol=4
cd-vols=
no-issue=2
article-no=
start-page=025301
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2022
dt-pub=20220317
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=High-quality micro-shape fabrication of monocrystalline diamond by nanosecond pulsed laser and acid cleaning
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=The flat plane of small surface roughness below 0.1 mu m average roughness was obtained for monocrystalline diamond by nanosecond pulsed laser irradiation of 1060 nm and post-process acid cleaning, at a laser fluence around the material removal threshold value. The glossy and flat plane at the bottom of the micro-groove was parallel to the top surface of the specimen, although the round beam of Gaussian mode was irradiated in the direction perpendicular to the top surface of specimen. The square beam of top-hat mode produced a shallower micro-groove with a wider, flatter bottom compared with the round beam in Gaussian mode. The creation method of the flat plane with small surface roughness was discussed in the arrangement strategy of linear micro-grooving by the square beam of top-hat mode. Normal side-by-side repetition of linear micro-grooving did not create a flat plane with constant depth. Therefore, a two-step scanning method was proposed in order to overcome the problem in the normal side-by-side repetition of liner micro-grooving. Non-removal areas were partly retained between the processing lines in the first step, and the laser scanning was conducted on the retained area in the second step. The newly proposed two-step scanning method was practical and useful to create a widely flat plane with small surface roughness, and the two-step scanning method provided superior control over the micro-groove depth. This proposed method can reduce the surface roughness in addition to the shape creation of monocrystalline diamond, and it can be used as a high-quality micro-shape fabrication method of monocrystalline diamond.
en-copyright=
kn-copyright=

en-aut-name=OkamotoYasuhiro
en-aut-sei=Okamoto
en-aut-mei=Yasuhiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=OkuboTubasa
en-aut-sei=Okubo
en-aut-mei=Tubasa
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=KajitaniAtsuya
en-aut-sei=Kajitani
en-aut-mei=Atsuya
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=OkadaAkira
en-aut-sei=Okada
en-aut-mei=Akira
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

affil-num=1
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=2
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=3
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=4
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=
en-keyword=monocrystalline diamond
kn-keyword=monocrystalline diamond
en-keyword=nanosecond pulsed laser
kn-keyword=nanosecond pulsed laser
en-keyword=flat surface
kn-keyword=flat surface
en-keyword=smooth surface
kn-keyword=smooth surface
en-keyword=micro-grooving
kn-keyword=micro-grooving
END

start-ver=1.4
cd-journal=joma
no-vol=17
cd-vols=
no-issue=1
article-no=
start-page=014010
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2021
dt-pub=20211229
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Evaluation of nitrogen loading in the last 80 years in an urbanized Asian coastal catchment through the reconstruction of severe contamination period
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Most semi-enclosed seas have experienced severe eutrophication owing to high nutrient loading from rivers during rapid population growth periods. In Japan, the coastal areas of some megacities (e.g. Tokyo and Osaka) experienced considerable economic growth during the 1960s-1970s. Therefore, determining the amount of nutrient loading during this period is essential to undertake measures for the conservation of coastal environments. However, determining the nutrient loading that occurred several decades ago is generally difficult owing to lacking water quality records. In this study, the nitrogen loading in the Yamato River catchment, an urbanized coastal catchment in Asia, for 80 years from the 1940s to the 2010s is reconstructed using the Soil and Water Assessment Tool. We considered factors such as population growth, wastewater treatment plant (WWTP) construction, and changes in land and fertilizer usage in different urbanization stages. Results show that the total nitrogen loading in the catchment peaked in the 1970s at 6616 tons yr(-1) owing to untreated wastewater discharge and rapid increase in population growth. By reducing 57% of the nitrogen loading in the 2010s from the catchment, WWTPs have been instrumental in improving the water environment. The decrease in and integration of agricultural land has reduced nitrogen loading attributed to nonpoint sources; however, this reduction was not obvious because of the high fertilizer usage before the 2000s. Overall, the findings of this study provide a comprehensive understanding of the impact of rapid urbanization in an Asian coastal catchment on nitrogen loading during the high economic growth period in the past. This study will be useful for the long-term assessment of nutrient loading in other.
en-copyright=
kn-copyright=

en-aut-name=WangKunyang
en-aut-sei=Wang
en-aut-mei=Kunyang
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=OnoderaShin-Ichi
en-aut-sei=Onodera
en-aut-mei=Shin-Ichi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=SaitoMitsuyo
en-aut-sei=Saito
en-aut-mei=Mitsuyo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

affil-num=1
en-affil=Graduate School of Integrated Arts and Sciences, Hiroshima University
kn-affil=

affil-num=2
en-affil=Graduate School of Advanced Science and Engineering, Hiroshima University
kn-affil=

affil-num=3
en-affil=Graduate School of Environmental and Life Science, Okayama University
kn-affil=
en-keyword=long-term
kn-keyword=long-term
en-keyword=nitrogen loading
kn-keyword=nitrogen loading
en-keyword=rapid urbanization
kn-keyword=rapid urbanization
en-keyword=popilation growth
kn-keyword=popilation growth
en-keyword=land use change
kn-keyword=land use change
en-keyword=wastewater treatment plant
kn-keyword=wastewater treatment plant
END

start-ver=1.4
cd-journal=joma
no-vol=3
cd-vols=
no-issue=3
article-no=
start-page=034008
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2021
dt-pub=20210412
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Simulating the redox potentials of unexplored phenazine derivatives as electron mediators for biofuel cells
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=In this research, we aimed to establish a guideline for designing electron mediators suitable for biofuel cells. A redox potential simulator was fabricated by combining density functional theory calculation and experiment, allowing us to select molecules with appropriate redox potentials efficiently. Previously, mediators have been developed depending on the trials and errors; thus, our strategy will speed up the development of biofuel cells with outstanding performances.
en-copyright=
kn-copyright=

en-aut-name=NakagawaRyo
en-aut-sei=Nakagawa
en-aut-mei=Ryo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=NishinaYuta
en-aut-sei=Nishina
en-aut-mei=Yuta
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=2
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=
en-keyword=redox potential
kn-keyword=redox potential
en-keyword=phenazine
kn-keyword=phenazine
en-keyword=mediator
kn-keyword=mediator
en-keyword=simulation
kn-keyword=simulation
en-keyword=DFT
kn-keyword=DFT
END