Nara Prefecture, Japan
Nara Prefecture, Japan

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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.


Okuyama M.,Archaeological Institute of Kashihara | Sato M.,Nara National Research Institute for Cultural Properties | Akada M.,Nara National Research Institute for Cultural Properties
Sen'i Gakkaishi | Year: 2014

The precise identification of bast fibers such as ramie and hemp found at several archaeological sites is a very difficult problem because organic materials are usually heavily degraded during the long term preservation at underground or mound. Both excavated ramie and hemp usually show very similar degraded FT-IR spectra (glober light source). The authors are continuing to study the identification of several kinds of archaeological silk and vast fibers using BL43IR beam line (FT-IR micro-spectroscopy) at SPring-8. It has already known that excavated ramie and hemp show the possibility of distinguish ramie from hemp under polarized light source. In this report, various modern ramie fibers are analyzed by detailed IR polarization measurement. As a result of the measurement, the absorption band of 1160 cm-1 disappeared at 45° (angle of polarizer) irrespective of sample history. In the next measurement, the disappearance angle of specific peak of modern hemp (several origins) will be confirmed. The determination of specific disappearance of certain peak for ramie or hemp will be effective for the identification of each fiber.


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

The scientific identification of excavated bast fibers (mainly hemp and ramie) is one of the important procedures for the conservation of textile cultural properties. In this paper, the new procedure to distinguish the kind of excavated bast fibers was proposed. Though excavated bast fibers are usually degraded by the long-term preservative environment, it was confirmed that they show still dichroism in infrared spectroscopy. Since the allowed amount of sampling for scientific analysis is severely limited in archaeology or in cultural properties, the authors used polarized synchrotron FT-IR Micro-spectroscopy. All of the bast fibers showed peaks at 1160, 1110, 1060, 670, 620 and 560cm -1. The corresponding modern reference bast fibers also show similar dichroism in polarized FT-IR Micro-spectroscopy. Though SEM images of excavated bast fibers indicate the degraded appearance, the results of polarized FT-IR spectrum show that a part of the molecular orientation of cellulose and hemicelluloses are still remained in fiber structure. The authors are continuing the research for the identification of excavated bast fibers using polarized FT-IR Micro-spectroscopy.


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.


Okuyama M.,Archaeological Institute of Kashihara | Sato M.,Nara National Research Institute for Cultural Properties | Akada M.,Kyoto Institute of Technology | Moriwaki T.,Japan Synchrotron Radiation Research Institute
Bunseki Kagaku | Year: 2010

Excavated natural fibers (silk, hemp and ramie) found at three tumuli (3C-6C A.D.) in Nara prefecture were investigated by using synchrotron radiation FT-IR microscopy at JASRI (SPring-8), beamline BL43IR. While three tumuli were kept in different long-term preservative environments, comparative studies on excavated fibers were performed for the identification of textile fibers, and for investigating the degraded state of respective fibers. Silk fibers are usually heavily degraded, and hence amide I and amide II peak patterns show different appearances compared with that of modern reference silk fibers. These phenomena are in accordance with the present author's analysis published separately. In short, the change in the spectral pattern is mainly due to transformation of the second structure components of the amide II peak during long-term preservation in various environments. Besides, the spectra pattern sometimes shows a small variation in the co-presence of metallic objects in tumulus. Plant fibers, such as hemp or ramie, are not severely degraded compared with silk fibers, and they usually show common spectra with plant fibers of a modern reference material. Since the plant fibers are in principle composed of cellulose molecules, exact identifications of materials are rather difficult by only the infrared spectrum. In summary, it was shown that excavated textile fibers sometimes show the small variation in the spectral pattern according to a difference in the preserved environment. © 2010 The Japan Society for Analytical Chemistry.


Okuyama M.,Archaeological Institute of Kashihara | Sato M.,Nara National Research Institute for Cultural Properties
Sen'i Gakkaishi | Year: 2015

It is already known that the infrared spectroscopy is one of the most useful method for the identification of cultural properties, especially for organic materials. However usual analytical procedure, such as Transmission (TR) or Attenuated Total Reflection measurement (ATR), requires preliminary treatment of sampling, and sometimes give damages to valuable samples by mixing or pressing. Contrary to this, Photoacaustic Spectroscopy (PAS) uses totally non-destructive procedures. To clarify the advantage of PAS compared with other procedures, some kinds of natural fibers (processed silk, hemp and ramie) were investigated in this study using PAS, TR or ATR. As a results, we confirmed that PA spectra of these samples were almost identical with that of other procedures (TR or ATR), and PAS could measure using very small amount of samples. We are further continuing the PAS study using various kind of organic cultural properties.


Akada M.,Kyoto Institute of Technology | Sato M.,Nara National Research Institute for Cultural Properties | Okuyama M.,Archaeological Institute of Kashihara
Journal of Textile Engineering | Year: 2010

The almost degraded silk fibers show deformed infrared spectra compared with that of reference silk fibers. In this report, the polarized micro infrared spectroscopy was used to clarify the reason for the deformation of spectrum. Since the polarized light is sensitive to the change in the secondary structure of fibroin molecules, the change in the crystallinity and the peak intensity ratio of spectrum of degraded silk fibers were evaluated. At first, the axis of single silk fiber was set parallel to the polarized light of 90°, and the spectra was measured successively by changing the angle of diamond cell until the final position of 0°, namely perpendicular to the axis of single silk fiber. As a result of the experiments, it was found that the crystallinity increases with progress in degradation. Furthermore, the crystallinity is higher in the direction for 90° compared with that for 0°. Furthermore, the peak intensity ratio, Amide I / Amide II, was adopted as the measure of degradation. The measured value was generally higher compared with that of reference silk fibers. The correlation between the crystallinity and Amide I / Amide II ratio was also investigated. © 2009 The Textile Machinery Society of Japan.


Akada M.,Kyoto Institute of Technology | Sato M.,Nara National Research Institute for Cultural Properties | Okuyama M.,Archaeological Institute of Kashihara | Imadzu S.,Kyushu National Museum Ishizaka
Journal of Textile Engineering | Year: 2010

Excavated organic materials such as textile fabrics are usually heavily degraded and hence their scientific identification is rather difficult. The authors are continuing the analysis of degraded natural textile fibers using FT-IR microscopy to clarify their general characteristics at molecular level. In this report, the infrared spectra of silk fibers found at the Fujinoki tumulus were analyzed in detail. The most remarkable change of spectral patterns in degraded silk fibers compared with those of modern silk fibers was the broad superposed appearance of amide I and II absorption peaks. As a result of the investigation of the secondary structure of fibroin molecules, the main reason for the spectral deformation was found to be the increase in crystallinity associated with degradations. In this research, the FT-IR microscope at JASRI was used. It requires only very minute samples due to the bright IR light source using synchrotron radiation. This makes it convenient for the study of cultural properties. The identification of silk fibers in degraded state undoubtedly contributes to the understanding of historical features of the remains at a particular tumulus. © 2010 by The Textile Machinery Society of Japan.


Nagae T.,University of Toyama | Hadano A.,Archaeological Institute of Kashihara
Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals | Year: 2010

The microstructure of a copper bowl excavated from an Edo-period grave in Mukaiyama Ruins in Nara prefecture has been investigated. The sample was subjected to optical microscopy, scanning electron microscopy, electron probe microanalysis and X-ray diffraction analysis to obtain information about the microstructure of both the base metal and the corroded layers. The bowl was made of copper containing 0.9% lead. Annealing twins were observed in the α-Cu phase, which establishes that the bowl was forged and annealed. The corroded layers were composed mainly of cuprite, malachite and copper phosphate. It is thought that the copper phosphate acted as an inhibitor to corrosion. © 2010 The Japan Institute of Metals.


Nagae T.,University of Toyama | Srinivasan S.,National Institute of Advanced Studies | Ranganathan S.,National Institute of Advanced Studies | Pillai R.M.,John Cox Memorial CSI Institute of Technology | And 2 more authors.
ISIJ International | Year: 2014

Additions of large amounts of tin to copper lead to high tin bronzes with interesting combination of properties. Such high tin bronzes need to be carefully processed to avoid brittleness in compositions corresponding to beta and delta phases. The latter has been used in China, India, Korea and Japan to produce distortion free mirror images. This investigation is concerned with the bronze mirror from India where the tradition has survived in the village Aranmula in Kerala. The alloy has an exceptionally high tin content consisting almost entirely of the delta phase, which is an intermetallic compound (Cu31Sn8) of composition 32.6% tin. This is an ideal alloy to be polished into a mirror due to the silvery white color and high hardness. Its high brittleness is offset by an ingenious casting and polishing process. In addition to studying the composition and the casting involving a mould cum crucible method, thermographic analysis has been employed to follow the solidification sequence by looking at the thermal profile. It is correlated with the actual composition, processing parameters and the resultant microstructure, due to the cooling rate the alloy solidifies with a mild departure from the equilibrium phase diagram. Some observations regarding the structure of the delta phase which is a Hume-Rothery phase will be provided about its optical and mechanical properties.

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