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New Corrosion-Resistant Zn-Al-Mg Alloy Hot-Dip Galvanized Steel Sheet
( Kohei Tokuda ),( Yasuto Goto ),( Mamoru Saito ),( Hiroshi Takebayashi ),( Takeshi Konishi ),( Yuto Fukuda ),( Fumiaki Nakamura ),( Koji Kawanishi ),( Kohei Ueda ),( Hidetoshi Shindo ) 한국부식방식학회 2024 Corrosion Science and Technology Vol.23 No.2
In recent years, Zn-Al-Mg alloy galvanized steel sheets have been widely used as coated steel sheets to support social capital in the infrastructure field. A feature of Zn-Al-Mg alloy-coated steel sheets is that they provide a better corrosion protection period than Zn-coated steel sheets. In this study, the corrosion resistance of a new Zn-Al-Mg alloy-coated steel sheet was investigated and compared to that of conventional commercially available coated steel sheets. The investigation confirmed that increasing the Mg concentration in the Zn-Al-Mg-coated steel sheet improved corrosion resistance, which was more than 10 times that of the galvanized steel sheet specified in JIS G 3302. The study findings also confirmed that the corrosion resistance reached more than twice that of the coated steel sheet specified in JIS G 3323. If such galvanized steel sheets are applied to social infrastructures that are exposed to severely corrosive environments, the service life of the infrastructure might be extended.
Ueda, Kohei,Yoshida, Masaaki,Isegawa, Kazuhisa,Shirahata, Naoki,Amemiya, Kenta,Mase, Kazuhiko,Mun, Bongjin Simon,Kondoh, Hiroshi American Chemical Society 2017 The Journal of Physical Chemistry Part C Vol.121 No.3
<P>The nitric oxide (NO) reduction by carbon monoxide (CO) on Ir(111) surfaces under near ambient pressure conditions was studied by a combination of near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and mass spectrometry (MS), particularly paying attention to the dominant reaction pathway to formation of molecular nitrogen (N-2). Under a relatively low CO pressure condition (50 mTorr NO + 10 mTorr CO), two reaction pathways to form N-2 are clearly observed at different ignition temperatures (280 and 400 degrees C) and attributed to a reaction of NO adsorbed at atop site (NOatop) with atomic nitrogen (N-ad) and associative desorption of N-ad, respectively. Since the adsorption of NOatop is inhibited by CO adsorbed at atop site (COatop), the ignition of the NOatop + N-ad reaction strongly depends on the coverage of COatop; the ignition temperature shifts to higher temperature as increasing CO pressure. In contrast, for the Nad + Nad reaction the ignition temperature keeps almost constant (similar to 400 degrees C). The online MS results indicate that the latter reaction is the dominant pathway to N-2 formation and the, former one less contributes to N-2 formation with accompanying a small amount of nitrous oxide (N2O). No evidence for contribution of the isocyanate (NCO) species as an intermediate was observed in the operando NAP-XP spectra.</P>
Effect of Pressure on the Intermediate-valence Semiconductor SmB6 : 11B-NMR
Kohei Nishiyama,Takeshi Mito,Ko-ichi Ueda,Takehide Koyama,Takao Kohara,Gabriel Prist´aˇs,Slavom´ır Gab´ani,Mari´an Reiffers,Karol Flachbart,Yasuhiro Komaki,Mitsutane Kokubu,Hideto Fukazawa,and Yoh Koh 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
We report the first high-pressure 11B-NMR studies above 3 GPa on the intermediate-valencesemiconductor SmB6. A 11B-NMR line obtained at 4.9 GPa, the highest pressure for the measurements,and at 1.9 K shows quite similar a line shape to that at ambient pressure, indicating nostructural or magnetic phase transition up to this pressure. The temperature dependence of thespin lattice relaxation rate 1/T1 at 4.9 GPa still exhibits an activation-type temperature dependencecharacteristic of semiconductors, which reveals an obvious decrease in the insulating gap byabout 30% compared to the gap at ambient pressure. The present experimental facts of a finiteinsulator gap and no magnetic order at 4.9 GPa are consistent with recent transport measurementsperformed under better hydrostatic pressures.
MID- AND FAR-INFRARED PROPERTIES OF LOCAL ACTIVE GALACTIC NUCLEI
Ichikawa, Kohei,Ueda, Yoshihiro,Terashima, Yuichi,Oyabu, Shinki,Gandhi, Poshak,Matsuta, Keiko,Nakagawa, Takao The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We investigate the mid-infrared (MIR) to far-infrared (FIR) properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert telescope (BAT) all-sky hard X-ray (14-195 keV) survey, based on the cross correlation with the infrared survey catalogs of AKARI, IRAS and WISE. Out of 135 non-blazar AGNs in the Swift/BAT 9-month catalog, we obtain the MIR photometric data for 128 sources in either the 9, 12, 18, 22, and $25{\mu}m$ band. We find a good correlation between their hard X-ray and MIR luminosities ranging three orders of magnitude (42 < log ${\lambda}L_{\lambda}$(9, $18{\mu}m$) < 45), which is tighter than that with the FIR luminosities at $90{\mu}m$. Both X-ray unabsorbed and absorbed AGNs follow the same correlation, implying isotropic infrared emission, as expected in clumpy dust tori models rather than homogeneous ones.
Correlation between Charge Asphericity and Dzyaloshinskii-Moriya Interaction
Sanghoon Kim,Kohei Ueda,Gyungchoon Go,Peong-Hwa Jang,Kyung-Jin Lee,Abderrezak Belabbes,Aurelien Manchon,Motohiro Suzuki,Yoshinori Kotani,Tetsuya Nakamura,Kohji Nakamura,Tomohiro Koyama,Daichi Chiba,Ki 한국자기학회 2018 한국자기학회 학술연구발표회 논문개요집 Vol.2018 No.3
Current Status of the Diagnosis and Management of Pancreatic Neuroendocrine Tumors in Japan
Tetsuhide Ito,Masami Miki,Keijiro Ueda,Lingaku Lee,Ken Kawabe,Hisato Igarashi,Nao Fujimori,Kazuhiko Nakamura,Kohei Yasunaga,Robert T. Jensen,Takao Ohtsuka,Yoshihiro Ogawa Korean Society of Gastrointestinal Cancer 2016 Journal of digestive cancer reports Vol.4 No.2
The epidemiology of pancreatic neuroendocrine neoplasms (PNENs) in Asia has been clarified through epidemiological studies, including one conducted in Japan, and subsequently another in South Korea. As endoscopic ultrasonography (EUS) has become more widely accessible, endoscopic ultrasound-fine needle aspiration (EUS-FNA) has been performed in pancreatic tumors for which the clinical course was only monitored previously. This has enabled accurate diagnosis of pancreatic tumors based on the 2010 WHO classification; as a result, the number of patients with an accurate diagnosis has increased. Although surgery has been the standard therapy for PNENs, new treatment options have become available in Japan for the treatment of advanced or inoperable PNENs; of particular note is the recent introduction of molecular target drugs (such as everolimus and sunitinib) and streptozocin. Treatment for progressive PNENs needs to be selected for each patient with consideration of the performance status, degree of tumor differentiation, tumor mass, and proliferation rate. Somatostatin receptor (SSTR)-2 is expressed in many patients with neuroendocrine tumor. Somatostatin receptor scintigraphy (SRS), which can visualize SSTR-2 expression, has been approved in Japan. The SRS will be a useful diagnostic tool for locating neuroendocrine neoplasms, detecting distant metastasis, and evaluating therapy outcomes. In this manuscript, we review the latest diagnostic methods and treatments for PNENs.
AKARI INFRARED CAMERA OBSERVATIONS OF THE 3.3 μm PAH FEATURE IN Swift/BAT AGNs
Angel Castro,Takamitsu Miyaji,MAI SHIRAHATA,Kohei Ichikawa,SHINKI OYABU,David Clark,Masatoshi Imanishi,TAKAO NAKAGAWA,Yoshihiro Ueda 한국천문학회 2017 天文學論叢 Vol.32 No.1
Using the InfraRed Camera (IRC) on board the infrared astronomical satellite {\sl AKARI} we study the 3.3 $\mu$mpolycyclic aromatic hydrocarbon (PAH) feature and its connection to active galactic nucleus (AGN) propertiesfor a sample of 54 hard X-ray selected bright AGN, including both Seyfert 1 and Seyfert 2 type objects. The sample is selected from the 9-month {\sl Swift}/BAT survey in the 14--195 keV band and all of the sources have known neutralhydrogen column densities ($N_{\rm H}$). The 3.3 $\mu$m PAH luminosity ($L_{\rm 3.3{\mu}m}$) is used as a proxy for star-formation (SF)activity and hard X-ray luminosity ($L_{\rm 14-195keV}$) as an indicator of the AGN power. We explore for possible difference of SFactivity between type 1 (un-absorbed) and type 2 (absorbed) AGN. We use several statistical analyses taking the upper-limits of thePAH lines into account utilizing survival analysis methods. The results of our $\log(L_{\rm 14-195keV})$ versus $\log(L_{\rm 3.3{\mu}m})$regression shows a positive correlation and the slope for the type 1/unobscured AGN is steeper than that of type 2/obscured AGN at a$3\sigma$ level. Also our analysis shows that the circum-nuclear SF is more enhanced in type 2/absorbed AGN than type1/un-absorbed AGN for low $L_{\rm 14-195keV}$ luminosity/low Eddington ratio AGN, while there is no significant dependence of SF activityon the AGN type in the high $L_{\rm 14-195keV}$ luminosities/Eddington ratios.