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Ryuji Shikaku

Bio: Ryuji Shikaku is an academic researcher. The author has contributed to research in topics: Synchrotron radiation. The author has an hindex of 2, co-authored 4 publications receiving 9 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a fragment of a colorless facet-cut glass vessel was collected at the Kamigamo Shrine, located in Kyoto, which was the capital city of Japan from late 8th century AD through the mid-19th century.

7 citations

Journal ArticleDOI
TL;DR: X-ray fluorescence analytical techniques were applied to two pieces of glass fragments because they are believed to be sampled from two important glassware, a facet-cut bowl and a deeply-blue colored dish, excavated from Niizawa Senzuka Tumulus No.126, Nara, Japan (late 5th century) as discussed by the authors.

7 citations

Journal ArticleDOI
TL;DR: In this article, an x-ray micro-imaging technique to visualize high-resolution structure of cultural heritages made of iron or copper has been developed, which utilizes high-energy x-rays from a bending magnet at the SPring-8 synchrotron radiation facility.
Abstract: An x-ray micro-imaging technique to visualize high-resolution structure of cultural heritages made of iron or copper has been developed. It utilizes high-energy x-rays from a bending magnet at the SPring-8 synchrotron radiation facility. A white x-ray beam was attenuated by 0.5 mm tungsten and 2.0 mm lead absorbers resulting in the peak energy of 200 keV. The tungsten absorber eliminated the photon energy peak below the absorption edge of lead. A sample was rotated over 180 degrees in 500 s and projection images were continuously collected with an exposure time of 500 ms by an sCMOS camera equipped with a scintillator. Tomographic reconstruction of an ancient sword containing of both copper and iron was successfully obtained at a voxel size of 14.8 μm. Beam hardening was found to cause 2.5 % differences in density in a reconstructed image of a homogeneous stainless-steel rod. Ring artefacts were reduced by continuously moving the absorbers. This work demonstrates feasibility of high-energy, high-resolutio...

5 citations

Journal ArticleDOI
TL;DR: The use of a portable X-ray fluorescence spectrometer revealed the provenance of a shard of a relief-cut glass bowl which was dedicated to ancient ritual on the sacred island of Okinoshima, Japan over a thousand years ago as discussed by the authors.

2 citations


Cited by
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Journal ArticleDOI
Tetsuya Yokoyama, Kazuhide Nagashima, Izumi Nakai, Edward D. Young, Yoshinari Abe, Jérôme Aléon, Conel M. O'd. Alexander, Sachiko Amari, Yuri Amelin, Ken ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, K. Ichida, Tsuyoshi Iizuka, Trevor Ireland, Akira Ishikawa, Motoo Ito, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Ann N. Nguyen, Larry R. Nittler, M. Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Shigekazu Yoneda, Hiroharu Yui, Ai-Cheng Zhang, Harold C. Connolly, Dante S. Lauretta, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Masahiko Arakawa, Atsushi Fujii, Masahiro Hayakawa, Naoyuki Hirata, Naru Hirata, Rie Honda, Chikatoshi Honda, Satoshi Hosoda, Yuichi Iijima, H. Ikeda, Masateru Ishiguro, Yoshiaki Ishihara, Takahiro Iwata, Kosuke Kawahara, Shota Kikuchi, Kohei Kitazato, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Yuya Mimasu, Akira Miura, Tomokatsu Morota, Satoru Nakazawa, Noriyuki Namiki, Hirotomo Noda, Rina Noguchi, Naoko Ogawa, Kazunori Ogawa, Tatsuaki Okada, Chisato Okamoto, Go Ono, M. Ozaki, Takanao Saiki, Naoya Sakatani, Hirotaka Sawada, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Yuichi Tsuda, Ryudo Tsukizaki, Koji Wada, Sei-ichiro Watanabe, Manabu Yamada, Tetsuya Yamada, Yukio Yamamoto, Hajime Yano, Yasuhiro Yokota, Keisuke Yoshihara, Makoto Yoshikawa, Kent Yoshikawa, Shizuho Furuya, Kentaro Hatakeda, Tasuku Hayashi, Yuya Hitomi, K. Kumagai, Akiko Miyazaki, Aiko Nakato, M. Nishimura, Hiromichi Soejima, Ayako I. Suzuki, Toru Yada, Daiki Yamamoto, Kasumi Yogata, M. Yoshitake, Shogo Tachibana, Hisayoshi Yurimoto 
09 Jun 2022-Science
TL;DR: The authors measured the mineralogy and bulk chemical and isotopic compositions of Ryugu samples and concluded that the samples mainly consist of secondary materials that were formed by aqueous alteration in a parent body, from which Ryugu later formed.
Abstract: Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measured the mineralogy and bulk chemical and isotopic compositions of Ryugu samples. The samples are mainly composed of materials similar to those of carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37° ± 10°C, about 5.2−0.7+0.8 million (statistical) or 5.2−2.1+1.6 million (systematic) years after the formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above ~100°C. The samples have a chemical composition that more closely resembles that of the Sun’s photosphere than other natural samples do. Description INTRODUCTION The Hayabusa2 spacecraft made two landings on the asteroid (162173) Ryugu in 2019, during which it collected samples of the surface material. Those samples were delivered to Earth in December 2020. The colors, shapes, and morphologies of the returned samples are consistent with those observed on Ryugu by Hayabusa2, indicating that they are representative of the asteroid. Laboratory analysis of the samples can determine the chemical composition of Ryugu and provide information on its formation and history. RATIONALE We used laboratory analysis to inform the following questions: (i) What are the elemental abundances of Ryugu? (ii) What are the isotopic compositions of Ryugu? (iii) Does Ryugu consist of primary materials produced in the disk from which the Solar System formed or of secondary materials produced in the asteroid or on a parent asteroid? (iv) When were Ryugu’s constituent materials formed? (v) What, if any, relationship does Ryugu have with meteorites? RESULTS We quantified the abundances of 66 elements in the Ryugu samples: H, Li, Be, C, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Tl, Pb, Bi, Th, and U. There is a slight variation in chemical compositions between samples from the first and second touchdown sites, but the variations could be due to heterogeneity among the samples that were analyzed. The Cr-Ti isotopes and abundance of volatile elements are similar to those of carbonaceous meteorites in the CI (Ivuna-like) chondrite group. The Ryugu samples consist of the minerals magnetite, breunnerite, dolomite, and pyrrhotite as grains embedded in a matrix composed of serpentine and saponite. This mineral assemblage and the texture are also similar to those of CI meteorites. Anhydrous silicates are almost absent, which indicates extensive liquid water–rock reactions (aqueous alteration) in the material. We conclude that the samples mainly consist of secondary materials that were formed by aqueous alteration in a parent body, from which Ryugu later formed. The oxygen isotopes in the bulk Ryugu samples are also similar to those in CI chondrites. We used oxygen isotope thermometry to determine the temperature at which the dolomite and magnetite precipitated from an aqueous solution, which we found to be 37° ± 10°C. The 53Mn-53Cr isotopes date the aqueous alteration at 5.2−0.7+0.8 million (statistical) or 5.2−2.1+1.6 million (systematic) years after the birth of the Solar System. Phyllosilicate minerals are the main host of water in the Ryugu samples. The amount of structural water in Ryugu is similar to that in CI chondrites, but interlayer water is largely absent in Ryugu, which suggests a loss of interlayer water to space. The abundance of structural water and results from dehydration experiments indicate that the Ryugu samples remained below ~100°C from the time of aqueous alteration until the present. We ascribe the removal of interlayer water to a combination of impact heating, solar heating, solar wind irradiation, and long-term exposure to the ultrahigh vacuum of space. The loss of interlayer water from phyllosilicates could be responsible for the comet-like activity of some carbonaceous asteroids and the ejection of solid material from the surface of asteroid Bennu. CONCLUSION The Ryugu samples are most similar to CI chondrite meteorites but are more chemically pristine. The chemical composition of the Ryugu samples is a closer match to the Sun’s photosphere than to the composition of any other natural samples studied in laboratories. CI chondrites appear to have been modified on Earth or during atmospheric entry. Such modification of CI chondrites could have included the alteration of the structures of organics and phyllosilicates, the adsorption of terrestrial water, and the formation of sulfates and ferrihydrites. Those issues do not affect the Ryugu samples. Those modifications might have changed the albedo, porosity, and density of the CI chondrites, causing the observed differences between CI meteorites, Hayabusa2 measurements of Ryugu’s surface, and the Ryugu samples returned to Earth. Representative petrography of a Ryugu sample, designated C0002-C1001. Colors indicate elemental abundances determined from x-ray spectroscopy. Lines of iron, sulfur, and calcium are shown as red, green, and blue (RGB) color channels in that order. Combinations of these elements are assigned to specific minerals, as indicated in the legend. All visible minerals were formed by aqueous alteration on Ryugu’s parent body.

55 citations

Journal ArticleDOI
01 Mar 2019-Micron
TL;DR: The state-of-the-art of the most relevant research related to the use of CT-Scanning is presented in this paper, which explores microstructural studies of materials used in various fields of engineering, with especial emphasis on concrete technology.

27 citations

Journal ArticleDOI
TL;DR: In this paper , the performance assessment of four different portable X-ray fluorescence spectroscopy (p-XRF) units and the reconciling of their output were conducted and the results showed the limitations in cross-referencing the data obtained from each unit and suggest procedures to overcome the issues.
Abstract: X-ray fluorescence spectroscopy is a non-destructive technique employed for elemental analysis of a wide range of materials. Its advantages are especially valued in archaeometry, where portable instruments are available. Considering ancient glass, such instruments allow for the detection of some major, minor, and trace elements linked to the deliberate addition of specific components or to impurities in the raw materials of the glass batch. Besides some undoubted advantages, portable XRF (p-XRF) has some limitations that are addressed in this study. The performance assessment of four different p-XRF units and the reconciling of their output were conducted. The results show the limitations in cross-referencing the data obtained from each unit and suggest procedures to overcome the issues. The p-XRF units were tested on the set of Corning reference glasses and on a small set of archaeological glasses with known composition. The compatibility of the output was assessed using multivariate statistical tools. Such a workflow allows us to consider data from multiple sources in the same frame of reference.

9 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated differences in vegetable oil oxidation regarding three packaging materials: ceramic (C), glass (G), and metal (M); the hydrophilicities of material surfaces were assessed by contact angle.

9 citations

Journal ArticleDOI
TL;DR: In this article, a fragment of a colorless facet-cut glass vessel was collected at the Kamigamo Shrine, located in Kyoto, which was the capital city of Japan from late 8th century AD through the mid-19th century.

7 citations