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AKARI NEAR-INFRARED SPECTROSCOPIC SURVEY FOR COMETARY VOLATILES
Ootsubo, T.,Kawakita, H.,Kobayashi, H.,Usui, F.,AKARI SOSOS team, AKARI SOSOS team The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We performed a spectroscopic survey for cometary volatiles with the Infrared Camera onboard the Japanese infrared satellite AKARI. The observations were carried out in the near-infrared wavelength range in the period from 2008 June to 2010 January. In this paper, we summarize the observations and results of the AKARI survey for the mixing ratios of major volatiles in comets. We derived the $2.5-5{\mu}m$ spectra of 18 comets including both Oort cloud comets and Jupiter-family comets. Prominent emission bands in the observed spectra are the fundamental vibrational bands of water ($H_2O$) at $2.7{\mu}m$ and carbon dioxide ($CO_2$) at $4.3{\mu}m$. The fundamental vibrational band of carbon monoxide (CO) at $4.7{\mu}m$ and the broad emission feature probably related to C-H bearing molecules can also be recognized around the $3.4-3.5{\mu}m$ region in some comets. We detect $CO_2$ in 17 out of 18 comets, and derived gas production rate ratios of $CO_2$ with respect to $H_2O$ in 17 comets. We detect a reliable CO emission band only in three of the comets. Our data set provides the largest homogeneous database of $CO_2/H_2O$ ratios in comets obtained so far.
AKARI mid-infrared slitless spectroscopic survey of star-forming galaxies at <i>z</i> ≲ 0.5
Ohyama, Y.,Wada, T.,Matsuhara, H.,Takagi, T.,Malkan, M.,Goto, T.,Egami, E.,Lee, H.-M.,Im, M.,Kim, J.H.,Pearson, C.,Inami, H.,Oyabu, S.,Usui, F.,Burgarella, D.,Mazyed, F.,Imanishi, M.,Jeong, W.-S.,Miya EDP Sciences 2018 Astronomy and astrophysics Vol.618 No.-
<P><I>Context.</I> Deep mid-infrared (MIR) surveys have revealed numerous strongly star-forming galaxies at redshift <I>z</I> ≲ 2. Their MIR fluxes are produced by a combination of continuum and polycyclic aromatic hydrocarbon (PAH) emission features. The PAH features can dominate the total MIR flux, but are difficult to measure without spectroscopy.</P><P><I>Aims.</I> We aim to study star-forming galaxies by using a blind spectroscopic survey at MIR wavelengths to understand evolution of their star formation rate (SFR) and specific SFR (SFR per stellar mass) up to <I>z</I> ≃ 0.5, by paying particular attention to their PAH properties.</P><P><I>Methods.</I> We conducted a low-resolution (<I>R</I> ≃ 50) slitless spectroscopic survey at 5-13 <I>μ</I>m of 9 <I>μ</I>m flux-selected sources (>0.3 mJy) around the north ecliptic pole with the infrared camera (IRC) onboard AKARI. After removing 11 AGN candidates by using the IRC photometry, we identify 48 PAH galaxies with PAH 6.2, 7.7, and 8.6 <I>μ</I>m features at <I>z</I> < 0.5. The rest-frame optical-MIR spectral energy distributions (SEDs) based on CFHT and IRC imaging covering 0.37-18 <I>μ</I>m were produced, and analysed in conjunction with the PAH spectroscopy. We defined the PAH enhancement by using the luminosity ratio of the 7.7 <I>μ</I>m PAH feature over the 3.5 <I>μ</I>m stellar component of the SEDs.</P><P><I>Results.</I> The rest-frame SEDs of all PAH galaxies have a universal shape with stellar and 7.7 <I>μ</I>m bumps, except that the PAH enhancement significantly varies as a function of the PAH luminosities. We identify a PAH-enhanced population at <I>z</I> ≳ 0.35, whose SEDs and luminosities are typical of luminous infrared galaxies. They show particularly larger PAH enhancement at high luminosity, implying that they are vigorous star-forming galaxies with elevated specific SFR. Our composite starburst model that combines a very young and optically very thick starburst with a very old population can successfully reproduce most of their SED characteristics, although we cannot confirm this optically think component from our spectral analysis.</P>
Usui, T.,Urano, K.,Suzuki, S.,Hioki, K.,Maruyama, Ch.,Tomisawa, M.,Ohnishi, Y.,Suemizu, H.,Yamamoto, S. Korean Society of ToxicologyKorea Environmental Mu 2001 Toxicological Research Vol.17 No.-
The international pharmaceutical and regulatory communities had been recognizing the limited utility of conventional rodent carcinogenicity study particularly on the second species, mouse, after intense investigation of carcinogenicity data base worldwide, and a new scheme for carcinogenicity testing for pharmaceuticals was proposed at the Expert Working Group on Safety in the International Conference on Harmonization (ICH) in 1996. CB6F 1-Tg rasH2 mouse carrying human prototype c-Ha-ras gene with its own promoter/enhancer is one oj the new carcinogenicity assay model for human cancer risk assessment. Studies have been conducted since 1992 to validate the transgenic (Tg) mice for rapid carcinogenicity test-ing, short term (26 weeks) studies with genotoxic (by Salmonella), non-genotoxic carcinogens, genotoxic non-carcinogens, non-genotoxic non-carcinogens revealed relatively high concordance oj the response of the Tg mouse with classical bioassay across classes of carcinogenic agents. Mechanistic basis for carcinogensis in the model are being elucidated in terms of the role of overexpression and/or point mutation of the transgene. This report review the initial studies of validation of the model and preliminary results of on-going ILSI HESI ACT project will be presented.
Temperature and diameter effect on hydrodynamic characteristic of surfactant drag-reducing flows
Y.S. Indartono,H. Usui,H. Suzuki,Y. Komoda 한국유변학회 2005 Korea-Australia rheology journal Vol.17 No.4
Hydrodynamic characteristic of surfactant drag-reducing flows is still not fully understood. This work investigated the temperature and diameter effect on hydrodynamic characteristic of cationic surfactant drag reducing flows in pipes. Solution of oleyl bishydroxyethyl methyl ammonium chloride (Ethoquad O/12), 900 ppm, as a cationic surfactant and sodium salicylate (NaSal), 540 ppm, as a counter-ion was tested at 12, 25, 40, and 50oC in pipes with diameter of 13, 25, and 40 mm. Drag reduction effectiveness of this surfactant solution was evaluated in 25 mm pipe from 6 to 75oC. Rheological characteristic of this solution was measured by stress control type rheometer with cone-and-plate geometry. Scale-up laws proposed by previous investigators were used to evaluate the flow characteristic of the solution. It was found that this surfactant solution has clear DR capability until 70oC. Result of this work suggested that temperature has a significant influence in changing the hydrodynamic entrance length of surfactant drag reducing flows. From rheological measurement, it was found that the solution exhibits Shear Induced Structure at all temperatures with different degree of peak viscosity and critical shear rate.
Temperature and diameter effect on hydrodynamic characteristic of surfactant drag-reducing flows
Indartono Y.S.,Usui H.,Suzuki H.,Komoda Y. The Korean Society of Rheology 2005 Korea-Australia rheology journal Vol.17 No.4
Hydrodynamic characteristic of surfactant drag-reducing flows is still not fully understood. This work investigated the temperature and diameter effect on hydrodynamic characteristic of cationic surfactant drag reducing flows in pipes. Solution of oleyl bishydroxyethyl methyl ammonium chloride (Ethoquad O/12), 900 ppm, as a cationic surfactant and sodium salicylate (NaSal), 540 ppm, as a counter-ion was tested at 12, 25, 40, and $50^{\circ}C$ in pipes with diameter of 13, 25, and 40 mm. Drag reduction effectiveness of this surfactant solution was evaluated in 25 mm pipe from 6 to $75^{\circ}C$. Rheological characteristic of this solution was measured by stress control type rheometer with cone-and-plate geometry. Scale-up laws proposed by previous investigators were used to evaluate the flow characteristic of the solution. It was found that this surfactant solution has clear DR capability until $70^{\circ}C$. Result of this work suggested that temperature has a significant influence in changing the hydrodynamic entrance length of surfactant drag reducing flows. From rheological measurement, it was found that the solution exhibits Shear Induced Structure at all temperatures with different degree of peak viscosity and critical shear rate.
오병훈,C.S. Seo,D.H. Chang,K. Watanabe,K. Usui,K.W. Lee,M. Kawai,M. Kashiwagi,S.H. Jeong,T. Inoue,T.S. Kim,Y. Ikeda 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
A prototype ion source for the KSTAR Neutral Beam (NB) heating system has a multi-cusp plasma chamber with a filament array to produce and maintain a large volume of a uniform and high-density plasma. The filament configuration proper to the structure of cusp magnetic fields is one of the most important factors governing the discharge characteristics of the plasma. The discharge performance of the KSTAR prototype ion source in a fixed-cusp field has been investigated experimentally for three different filament configurations: 1) 32 filaments with a TFTR layer; 2) 32 filaments in a uniformly distributed layer; and 3) 24 filaments in an electron-effective layer. The arc discharge efficiency, defined as the ratio of the ion density to the input arc power, and the plasma uniformity measured by 8 Langmuir probes distributed around the large beam extraction area are the key parameters in estimating the discharge performance of the ion source. The experimental results show that it is necessary to modify not only the filament configuration but also the structure of the cusp magnetic field in the bucket chamber to get a higher plasma efficiency in the source.
Visible-wavelength spectroscopy of subkilometer-sized near-Earth asteroids with a low delta-v
Kuroda, D.,Ishiguro, M.,Takato, N.,Hasegawa, S.,Abe, M.,Tsuda, Y.,Sugita, S.,Usui, F.,Hattori, T.,Iwata, I.,Imanishi, M.,Terada, H.,Choi, Y.-J.,Watanabe, S.-i.,Yoshikawa, M. Astronomical Society of Japan 2014 Publications of the Astronomical Society of Japan Vol.66 No.3