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Kirino F.,Tokyo University of the Arts | Kitada M.,Nara National Research Institute for Cultural Properties
Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals | Year: 2015

The microstructures of a corrosion layer formed on the surface of two Japanese oldest coins, Wadoukaichin (surface color: dark brown and green) were studied. Compositions of these coins are that main element is Cu and Sn and traces are Pb, Fe and As. X-ray diffraction patterns show that copper di-hydroxide (Cu(OH)2 2H2O), CuuiS and Cu2O are detected on the surface corrosion layer of dark brown sample, and Cu2(CO3) (OH)2 (malachite), Cu3(CO3)2(OH)2 (azurite) and Cu2O are detected on the surface corrosion layer of green sample. Optical microscope images show that the surface corrosion layer of dark brown sample is porous, and blue and green grains on the brown layer are existed on that of green sample. From spectrographs of these grains, the peak wavelength of green grains is matched to that of malachite, but this of blue grains is shifted to long wavelength side of about 40 nm at azurite on an influence of trace contaminations. The corrosion layer has two layers, surface layer is plate-like texture, and under layer is aggregation microstructure from TEM observation. The crystal structure of these two layers is matched to azurite from the electron beam diffraction patterns. © 2015 The Japan Institute of Metals and Materials. Source

Okuyama M.,Archaeological Institute of Kashihara | Sato M.,Nara National Research Institute for Cultural Properties | Akada M.,Kyoto Institute of Technology
Sen'i Gakkaishi | Year: 2012

To preserve excavated archaeological textile fibers, a preliminary investigation of materials and the degraded state of samples is indispensable. The excavated samples are valuable because the remaining amounts are usually scarce and often heavily degraded. In the past, infrared microscopic analysis has been used to overcome the above-mentioned limitation and has sufficient sensitivity for the analysis. However, the identification of bast fibers, such as hemp and ramie, using FT-IR, is rather difficult because their infrared spectra resemble each other. In this report, we investigated a procedure using a polarized radiation beam for the FT-IR microscope at JASRI (SPring-8) Beamline BL43IR for the identification of bast fibers. A minute amount of sample fibers was pressed by diamond plates to make a flat thin layer. The polarized absorbance spectrum of the sample on the diamond plate was measured. The polarizer was rotated from 0° to 90°, measuring the spectrum at 15° intervals. Both of the bast fibers, hemp and ramie, showed a decrease in the absorption peaks at 1428,1371,1160,1110, and 1060cm -1 with increase in the rotation angle of polarizer. Since the absorption peak intensity at 2900cm -1 of both fibers remained constants, the decreases were expressed as the ratios to the 2900cm -1 values of hemp and ramie. The plotted curves showing the relation between peak intensity versus polarizer angle are distinctly different between hemp and ramie. The infrared dichroism could be due to the difference in molecular orientation of the fiber components (cellulose and hemicelluloses) of hemp and ramie. Source

Tamura T.,Nara National Research Institute for Cultural Properties | Oga K.,Nara Womens University
Microchemical Journal | Year: 2016

This study examines the chemical compositions, colorants, and bead-making techniques of natron glass beads excavated in Japan. The authors classified the natron glass discussed in this study into seven main types, as well as other minor types, based on their chemical compositions. We also compared these specimens with natron glass excavated in the Mediterranean world. Type B2, which was distributed in the first half of the 5th century CE, corresponds to Levantine I type; Type A1, which was distributed mainly in the 2nd century CE, is likely to correspond to specimens containing antimony only as decolorant. However, others do not obviously match any existing groups. The results of the measurement of lead isotope ratios revealed relatively similar values between the natron glass analyzed in this study and the ore containing lead found in Iran. This showed the origin of cobalt added as colorants. © 2015 Elsevier B.V. Source

Okuyama M.,Archaeological Institute of Kashihara | Sato M.,Nara National Research Institute for Cultural Properties | Akada M.,Kyoto Institute of Technology
Sen'i Gakkaishi | Year: 2011

The ionic liquid is a salt which is usually liquid at room temperature. The vapor pressure of ionic liquid is so low that vaporization during experiment is disregarded. The utility of ionic liquid was revealed for the prevention of charge up phenomenon of fiber samples in the SEM observation. The ionic liquid used in this investigation was 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4). The textile samples were modern hemp, silk and excavated fibers from a tumulus (early Kofun Period) in Nara prefecture. Prior to the SEM observation, fiber samples were soaked in 0.1 M EMI-BF4/ethanol solution for 5, 10, 30, 60 minutes, respectively. The all of soaked samples showed distinct SEM images compared with that of Au-sputtered procedure irrespective of soaking time. The modern silk fibers showed however clear SEM images only at low magnification. Besides, the SEM images were distorted at high magnification due to the charge up phenomenon. Though excavated samples also gave clear SEM images, they were separately investigated by FT-IR microscopy to find out any changes in chemical composition before and after soaking treatment. Any appreciable changes were not found even after soaking. In summary, EMI-BF4 soaking was superior to prevent the charge up phenomenon of fibers and hence to obtain clearer SEM images compared with that of Au-sputtering procedure. Besides, in connection with the versatility of sample preparation procedure, EMI-BF4 is an appropriate reagent for SEM observation of textile materials. Source

Kitaba I.,Kobe University | Harada M.,Kobe University | Hyodo M.,Kobe University | Katoh S.,Museum of Nature and Human Activities | And 2 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2011

We report climate and sea-level variation for the marine oxygen isotope stage (MIS) 21, encompassing the end of the Mid-Pleistocene climate transition (MPT), based on pollen, diatom, and sulfur records from a 50-m thick sequence in a core from Osaka Bay. An extremely warm climate coincided with the sea level highstand of substage 21.5, when the warm-temperate element Quercus (Cyclobalanopsis) exceeds 40% of total arboreal pollen. This was followed by a warm-temperate to temperate and humid climate that continued until the end of MIS 21. A linear age model shows that climate was dominated by precessional cyclicity, with an inverse correlation between temperature and precipitation. The postglacial sea-level rise reached its highest peak in substage 21.5, when paleo-Osaka Bay reached its maximum extent including Kyoto and Nara Basins. At this time pelagic diatoms were dominant in the central part of the bay. Sea level dropped below the Osaka Bay sill (about -60. m at present) during substage 21.4, followed by a rise above the sill in substage 21.3, and a drop at 21.2. Sea level remained below the sill during substage 21.1. The thermal maximum and sea level peak occurred just after the rapid postglacial sea level rise, after which there was a gradual decline in temperature and sea level accompanied by precession-related oscillations; these features are typical of the post-MPT interglacials dominated by 100-ka cyclicity. These features may be a sign of termination of the MPT. © 2010 Elsevier B.V. Source

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