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Journal Articles

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

 Times Cited Count:30 Percentile:96.87(Astronomy & Astrophysics)

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:233 Percentile:99.74(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Journal Articles

Quick sample preparation for analysis of dioxins in flue gas from municipal solid waste incinerator

Takigami, Machiko; Arai, Hidehiko*; Hirota, Koichi; Taguchi, Mitsumasa; Hakoda, Teruyuki; Kojima, Takuji

Kankyo Kagaku, 14(1), p.13 - 23, 2004/03

The Japan Atomic Energy Research Institute undertook a pilot scale electron beam decompostion of dioxins in the flue gases from the municipal solid waste incinerator at the Takahama Clean Center. The conventional method, following the Japan Industrial Standards (JIS) method, takes 2 weeks at least to extract and purify dioxins from the flue gases for analysis by GC/MS. However, using a carbon adsorbent, the time required for the extraction of dioxins was shortened from 16 to 2.5 hours. Further improvements in the clean up process enabled the overall time to be reduced to less than a half of that rquired by the JIS method. Using this simplified method allows analysts, who are not practiced in the pretreatment of flue gases, to prepare samples for dioxin analysis by GC/MS. The sampling and pretreatment of the flue gases can, with this process, be completed within 4 days with accuracy comparable to JIS method.

Journal Articles

Radiation-induced decomposition of trace amounts of 17 $$beta$$-estradiol in water

Kimura, Atsushi; Taguchi, Mitsumasa; Arai, Hidehiko*; Hiratsuka, Hiroshi*; Namba, Hideki; Kojima, Takuji

Radiation Physics and Chemistry, 69(4), p.295 - 301, 2004/03

 Times Cited Count:26 Percentile:82.85(Chemistry, Physical)

no abstracts in English

Journal Articles

Electron-beam decomposition of vaporized VOCs in air

Hirota, Koichi; Hakoda, Teruyuki; Arai, Hidehiko; Hashimoto, Shoji

Radiation Physics and Chemistry, 65(4-5), p.415 - 421, 2002/11

 Times Cited Count:25 Percentile:81.57(Chemistry, Physical)

no abstracts in English

Journal Articles

The Real-time gas mass filter system for the analysis of products from trichloroethylene-air mixture during electron beam irradiation

Hakoda, Teruyuki; Arai, Hidehiko; Hashimoto, Shoji

Journal of Chemical Engineering of Japan, 34(10), p.1300 - 1308, 2001/10

 Times Cited Count:2 Percentile:25.16(Engineering, Chemical)

The continuous gas monitoring system using the mass filter (CGM-MS) was developed for the measurement of gaseous substances in air under atmospheric pressure. A capillary tube introduces the gases under atmospheric pressure into a mass filter installed in a vacuum chamber. The CGM-MS detected gaseous substances, such as sulfur dioxide, benzene and chlorobenzene, with detectable sensitivity of 0.7-1 ppmv. The monitoring system was also applied for the analysis of the products formed in electron beam irradiation of trichloroethylene (TCE) and air mixture. Dichloroacetyl chloride, carbonyl chloride (COCl$$_{2}$$), and chlorine (Cl$$_{2}$$) were quantitatively analyzed. Trichloroethylene and the products were oxidized and completely converted into carbon dioxide, Cl$$_{2}$$, and hydrochloric acid at 15 kGy. Carbonyl chloride is dissolved in an alkaline solution to be automatically oxidized into CO$$_{3}^{2-}$$ and Cl$$^{-}$$. The combination of the irradiation and the dissolution of the irradiated gas decreased to 7 from 15 kGy for the complete oxidation of TCE and the products.

Journal Articles

Electron-beam decomposition of carbon tetrachloride in air/nitrogen

Hirota, Koichi; Arai, Hidehiko; Hashimoto, Shoji

Bulletin of the Chemical Society of Japan, 73(12), p.2719 - 2724, 2000/12

 Times Cited Count:7 Percentile:38.38(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Electron beam

Hashimoto, Shoji; Arai, Hidehiko

Denki Gakkai Gijutsu Hokoku, (810), p.46 - 50, 2000/10

no abstracts in English

Journal Articles

Estimation of electron beam induced reaction rate through simulation

Arai, Hidehiko

Denki Gakkai Gijutsu Hokoku, (810), p.56 - 58, 2000/10

no abstracts in English

Journal Articles

Enhanced decomposition of dichloromethane in air by multi-pass electron beam irradiation

Wahyuni, S.*; Hirota, Koichi; Hakoda, Teruyuki; Arai, Hidehiko; Hashimoto, Shoji; Kawamoto, Fumio*; Mukunoki, Yasuo*

Bulletin of the Chemical Society of Japan, 73(8), p.1939 - 1943, 2000/08

 Times Cited Count:2 Percentile:16.99(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Treatment of drinking water and waste water

Arai, Hidehiko

Hoshasen Riyo Ni Okeru Saikin No Shimpo, p.183 - 192, 2000/06

no abstracts in English

Journal Articles

Low energy electron beam treatment of VOCs

Hashimoto, Shoji; Hakoda, Teruyuki; Hirota, Koichi; Arai, Hidehiko

Radiation Physics and Chemistry, 57(3-6), p.485 - 488, 2000/03

 Times Cited Count:26 Percentile:82.72(Chemistry, Physical)

no abstracts in English

Journal Articles

Dechlorination of chlorobenzene in air with electron beam

Hirota, Koichi; Hakoda, Teruyuki; Arai, Hidehiko; Hashimoto, Shoji

Radiation Physics and Chemistry, 57(1), p.63 - 73, 2000/01

 Times Cited Count:35 Percentile:88.44(Chemistry, Physical)

no abstracts in English

Journal Articles

New hopes to radiation water-treatment technology

Arai, Hidehiko

Hoshasen To Sangyo, (82), p.22 - 25, 1999/06

no abstracts in English

Journal Articles

Treatment of off-gases by electron beam irradiation

Arai, Hidehiko

Heisei-11-Nen Denki Gakkai Zenkoku Taikai Koen Rombunshu, p.S.1.1 - S.1.4, 1999/03

no abstracts in English

Journal Articles

Cupric ion effect on decomposition of tert-butanol in water by $$gamma$$-ray irradiation combined with ozone

M.Lee*; Arai, Hidehiko; Miyata, Teijiro

Environmental Applications of Ionizing Radiation, p.341 - 351, 1998/00

no abstracts in English

Journal Articles

Radiation-induced decoloration and sedimentation of colloidal disperse dyes in water

A.N.M.Bagyo*; Arai, Hidehiko; Miyata, Teijiro

Applied Radiation and Isotopes, 48(2), p.175 - 181, 1997/00

 Times Cited Count:17 Percentile:77.48(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Cyclodextrin addition effect on radiation-induced decomposition of chlorophenols in deoxygenated water

X.Huang*; Arai, Hidehiko; Matsuhashi, Shimpei; Miyata, Teijiro

Chemistry Letters, 0(2), p.159 - 160, 1996/00

no abstracts in English

Journal Articles

Enhanced phenol yield from radiation-induced decomposition of chlorophenols in deaerated water by addition of cyclodextrin and glucose

X.Huang*; Arai, Hidehiko; Matsuhashi, Shimpei; Miyata, Teijiro

Chemistry Letters, 0(4), p.273 - 274, 1996/00

no abstracts in English

Journal Articles

Report from Pacifichem '95

Arai, Hidehiko

Hoshasen To Sangyo, 0(69), p.36 - 37, 1996/00

no abstracts in English

42 (Records 1-20 displayed on this page)