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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>
2014-2015 MULTIPLE OUTBURSTS OF 15P/FINLAY
Ishiguro, Masateru,Kuroda, Daisuke,Hanayama, Hidekazu,Kwon, Yuna Grace,Kim, Yoonyoung,Lee, Myung Gyoon,Watanabe, Makoto,Akitaya, Hiroshi,Kawabata, Koji,Itoh, Ryosuke,Nakaoka, Tatsuya,Yoshida, Michitos American Astronomical Society 2016 The Astronomical journal Vol.152 No.6
<P>Multiple outbursts of a Jupiter-family comet (JFC), 15P/Finlay, occurred from late 2014 to early 2015. We conducted an observation of the comet after the first outburst and subsequently witnessed another outburst on 2015 January 15.6-15.7. The gas, consisting mostly of C-2 and CN, and dust particles expanded at speeds of 1110 +/- 180 m s(-1) and 570 +/- 40 m s(-1) at a heliocentric distance of 1.0 au. We estimated the maximum ratio of solar radiation pressure with respect to the solar gravity beta(max) = 1.6 +/- 0.2, which is consistent with porous dust particles composed of silicates and organics. We found that 10(8)-10(9) kg of dust particles (assumed to be 0.3 mu m - 1 mm) were ejected through each outburst. Although the total mass is three orders of magnitude smaller than that of the 17P/Holmes event observed in 2007, the kinetic energy per unit mass (10(4) J kg(-1)) is equivalent to the estimated values of 17P/Holmes and 332P/2010 V1 (Ikeya-Murakami), suggesting that the outbursts were caused by a similar physical mechanism. From a survey of cometary outbursts on the basis of voluntary reports, we conjecture that 15P/Finlay-class outbursts occur >1.5 times annually and inject dust particles from JFCs and Encke-type comets into interplanetary space at a rate of similar to 10 kg s(-1) or more.</P>
Optical and Near-infrared Polarimetry of Non-periodic Comet C/2013 US10 (Catalina)
Kwon, Yuna Grace,Ishiguro, Masateru,Kuroda, Daisuke,Hanayama, Hidekazu,Kawabata, Koji S.,Akitaya, Hiroshi,Nakaoka, Tatsuya,Itoh, Ryosuke,Toda, Hiroyuki,Yanagisawa, Kenshi,Lee, Myung Gyoon,Ohta, Kouji American Institute of Physics 2017 The Astronomical journal Vol.154 No.4
<P>We present an optical and near-infrared (hereafter NIR) polarimetric study of a comet C/2013 US10 (Catalina) observed on UT 2015 December 17-18 at phase angles of alpha - 52 degrees.1-53 degrees.1. Additionally, we obtained an optical spectrum and multi-band images to examine the influence of gas emission. We find that the observed optical signals are significantly influenced by gas emission; that is, the gas-to-total intensity ratio varies from 5 to 30% in the RC and 3%-18% in the I-C bands, depending on the position in the coma. We derive the 'gas-free dust polarization degrees' of 13.8% +/- 1.0% in the RC and 12.5% +/- 1.1% in the IC bands and a gray polarimetric color, i.e., -8.7% +/- 9.9% mu m(-1) in optical and 1.6% +/- 0.9% mu m(-1) in NIR. The increments of polarization obtained from the gas correction show that the polarimetric properties of the dust in this low-polarization comet are not different from those in high-polarization comets. In this process, the cometocentric distance dependence of polarization has disappeared. We also find that the RC-band polarization degree of the southeast dust tail, which consists of large dust particles (100 mu m(-1) mm), is similar to that in the outer coma where small and large ones are mixed. Our study confirms that the dichotomy of cometary polarization does not result from the difference of dust properties, but from depolarizing gas contamination. This conclusion can provide a strong support for similarity in origin of comets.</P>
Copper complexes of the non-innocent β-diketiminate ligand containing phenol groups
Takaichi, June,Ohkubo, Kei,Sugimoto, Hideki,Nakano, Motohiro,Usa, Daisuke,Maekawa, Hiroaki,Fujieda, Nobutaka,Nishiwaki, Nagatoshi,Seki, Shu,Fukuzumi, Shunichi,Itoh, Shinobu The Royal Society of Chemistry 2013 Dalton Transactions Vol.42 No.7
<P>A new type of non-innocent β-diketiminate ligand having redox active phenol groups (<B>LH<SUB>3</SUB></B>, fully protonated form) has been developed, and the structure, physical properties and reactivity of the supported copper(<SMALL>II</SMALL>) complex [Cu<SUP>II</SUP>(<B>L<SUP>3−</SUP></B>)]<SUP>−</SUP> (<B>L<SUP>3−</SUP></B>, fully deprotonated tri-anionic form) as well as the one-electron and two-electron oxidised complexes, [Cu<SUP>II</SUP>(<B>L&z.rad;<SUP>2−</SUP></B>)] and [Cu<SUP>II</SUP>(<B>L<SUP>−</SUP></B>)]<SUP>+</SUP>, have been examined in detail. The two-electron oxidised form [Cu<SUP>II</SUP>(<B>L<SUP>−</SUP></B>)]<SUP>+</SUP> exhibited hydrogen atom abstraction ability from 1,4-cyclohexadiene (CHD), whereas the one-electron oxidised form [Cu<SUP>II</SUP>(<B>L&z.rad;<SUP>2−</SUP></B>)] was found to disproportionate into [Cu<SUP>II</SUP>(<B>L<SUP>3−</SUP></B>)]<SUP>−</SUP> and [Cu<SUP>II</SUP>(<B>L<SUP>−</SUP></B>)]<SUP>+</SUP> during the course of the reaction with CHD.</P> <P>Graphic Abstract</P><P>Structure, physicochemical properties, and reactivity of the copper(<SMALL>II</SMALL>)-phenoxyl radical complexes of the non-innocent β-diketiminate ligand containing phenol groups are reported. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2dt32413j'> </P>
( Sun-young Lee ),( Naohisa Yoshida ),( Osamu Dohi ),( Sang Pyo Lee ),( Daisuke Ichikawa ),( Jeong Hwan Kim ),( In-kyung Sung ),( Hyung Seok Park ),( Eigo Otsuji ),( Yoshito Itoh ),( Chan Sup Shim ),( 대한간학회 2017 Gut and Liver Vol.11 No.3
Background/Aims: The presence of invasion is a diagnostic criterion of early gastric cancer (EGC) in Korea, whereas diagnosis in Japan is based on enlarged nuclei and prominent nucleoli. Moreover, the depth of invasion is the location of cancer cell infiltration in Korea, whereas it is the location of lymphovascular invasion (LVI) or cancer cell infiltration in Japan. We evaluated the characteristics of EGC with LVI to uncover the effects of different diagnostic criteria. Methods: Consecutive T1-stage EGC patients who underwent complete resection were included after endoscopic or surgical resection. The presence of LVI was evaluated. Results: LVI was present in 112 of 1,089 T1-stage EGC patients. LVI was associated with depth of invasion (p<0.001) and age (p=0.017). The prevalence of LVI in mucosal cancer was significantly higher in Korea (p<0.001), whereas that of submucosal cancer was higher in Japan (p=0.024). For mucosal EGC types, LVI was positively correlated with diagnostic criteria applied in Korea (p=0.017). For submucosal EGC types, LVI was positively correlated with Japanese criteria (p=0.001) and old age (p=0.045). Conclusions: The higher prevalence of LVI for mucosal EGC in Korea and for submucosal EGC in Japan indicates that different diagnostic criteria should be considered when reading publications from other countries. (Gut Liver 2017;11:383-391)