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Significantly high polarization degree of the very low-albedo asteroid (152679) 1998 KU<sub>2</sub>
Kuroda, Daisuke,Ishiguro, Masateru,Watanabe, Makoto,Hasegawa, Sunao,Sekiguchi, Tomohiko,Naito, Hiroyuki,Usui, Fumihiko,Imai, Masataka,Sato, Mitsuteru,Kuramoto, Kiyoshi EDP Sciences 2018 Astronomy and astrophysics Vol.611 No.-
<P>We present a unique and significant polarimetric result regarding the near-Earth asteroid (152679) 1998 KU2, which has a very low geometric albedo. From our observations, we find that the linear polarization degrees of 1998 KU2 are 44.6 ± 0.5% in the <I>R</I>C band and 44.0 ± 0.6% in the <I>V</I> band at a solar phase angle of 81.0°. These values are the highest of any known airless body in the solar system (i.e., high-polarization comets, asteroids, and planetary satellites) at similar phase angles. This polarimetric observation is not only the first for primitive asteroids at large phase angles, but also for low-albedo (<0.1) airless bodies. Based on spectroscopic similarities and polarimetric measurements of materials that have been sorted by size in previous studies, we conjecture that 1998 KU2 has a highly microporous regolith structure comprising nano-sized carbon grains on the surface.</P>
OPTICAL AND NEAR-INFRARED POLARIMETRY FOR A HIGHLY DORMANT COMET 209P/LINEAR
Kuroda, Daisuke,Ishiguro, Masateru,Watanabe, Makoto,Akitaya, Hiroshi,Takahashi, Jun,Hasegawa, Sunao,Ui, Takahiro,Kanda, Yuka,Takaki, Katsutoshi,Itoh, Ryosuke,Moritani, Yuki,Imai, Masataka,Goda, Shuhei IOP Publishing 2015 The Astrophysical journal Vol.814 No.2
<P>We conducted an optical and near-infrared polarimetric observation of the highly dormant Jupiter-Family Comet, 209P/LINEAR. Because of its low activity, we were able to determine the linear polarization degrees of the coma dust particles and nucleus independently, that is P-n = 30.3(-0.9)(+1.3)% at alpha = 92 degrees.2 and P-n = 31.0(-0.7)(+1.0)% at alpha = 99 degrees.5 for the nucleus, and P-c = 28.8(-0.4)(+0.4)% at alpha = 92 degrees.2 and 29.6(-0.3)(+0.3)% at alpha = 99 degrees.5 for the coma. We detected no significant variation in P at the phase angle coverage of 92 degrees.2-99 degrees.5, which may imply that the obtained polarization degrees are nearly at maximum in the phase-polarization curves. By fitting with an empirical function, we obtained the maximum values of linear polarization degrees P-max = 30.8% for the nucleus and P-max = 29.6% for the dust coma. The P-max of the dust coma is consistent with those of dust-rich comets. The low geometric albedo of P-v. =. 0.05 was derived from the slope-albedo relationship and was associated with high P-max. We examined P-max-albedo relations between asteroids and 209P, and found that the so-called Umov law seems to be applicable on this cometary surface.</P>
Fumihiko Ogata,Daisuke Imai,Megumu Toda,Masashi Otani,Naohito Kawasaki 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.34 No.-
Nickel hydroxide (Ni) was calcined at 270 and 400 8C (denoted Ni270 and Ni400), and the properties ofNi, Ni270, and Ni400 were investigated. In addition, the phosphate adsorption capabilities of Ni, Ni270,and Ni400 were evaluated by examination of the effects of contact time and solution pH, analysis of anadsorption isotherm, and study of desorption. The amounts of phosphate ion adsorbed by the differentsamples showed the order Ni < Ni400 < Ni270. Finally, phosphate ions adsorbed onto Ni270 could bedesorbed using sodium hydroxide, indicating that Ni270 can be used as a renewable adsorbent.
Ishiguro, Masateru,Kuroda, Daisuke,Hanayama, Hidekazu,Takahashi, Jun,Hasegawa, Sunao,Sarugaku, Yuki,Watanabe, Makoto,Imai, Masataka,Goda, Shuhei,Akitaya, Hiroshi,Takagi, Yuhei,Morihana, Kumiko,Honda, IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.798 No.2
<P>We report a new observation of the Jupiter family comet 209P/LINEAR during its 2014 return. The comet is recognized as a dust source of a new meteor shower, the May Camelopardalids. 209P/LINEAR was apparently inactive at a heliocentric distance r(h) = 1.6AU and showed weak activity at r(h) <= 1.4AU. We found an active region of <0.001% of the entire nuclear surface during the comet's dormant phase. An edge-on image suggests that particles up to 1 cm in size (with an uncertainty of factor 3-5) were ejected following a differential power-law size distribution with index q = -3.25 +/- 0.10. We derived a mass-loss rate of 2-10 kg s(-1) during the active phase and a total mass of approximate to 5 x 10(7) kg during the 2014 return. The ejection terminal velocity of millimeter- to centimeter-sized particles was 1-4ms(-1), which is comparable to the escape velocity from the nucleus (1.4ms(-1)). These results imply that such large meteoric particles marginally escaped from the highly dormant comet nucleus via the gas drag force only within a few months of the perihelion passage.</P>
Fumihiko Ogata,Ayaka Ueda,Shigeharu Tanei,Daisuke Imai,Naohito Kawasaki 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.35 No.-
We investigated the simultaneous removal of phosphate and nitrite ions from aqueous solutions by acombination treatment that used both PG-Ca (poly-g-glutamic acid combined with flocculating agents)and SB600 (soybeans treated with calcium chloride, hydrochloric acid and calcined at 600 8C). Phosphateions and nitrite ions were selectivity adsorbed by PG-Ca and SB600, respectively. The removalmechanism of phosphate ions from aqueous solution was related to the presence of calcium hydroxide(derived from PG-Ca), and that of nitrite ions was related to the presence of chloride ions at the surface ofSB600.