Proceedings of the Japan Academy, Series B
Online ISSN : 1349-2896
Print ISSN : 0386-2208
ISSN-L : 0386-2208
Volume 75 , Issue 3
Showing 1-6 articles out of 6 articles from the selected issue
  • Kaichi SUITO, Junpei NAMBA, Yasumitsu TSUTSUI, Akifumi ONODERA
    1999 Volume 75 Issue 3 Pages 43-45
    Published: 1999
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    A mixture of graphite and Fe2SiO4 in a ratio 2:3 by weight has been studied under pressures from 6 to 10GPa and temperatures between 1000 and 1960°C using an octahedral-anvil apparatus. At 8GPa, diamond with a size -10μm across was found to be formed at temperatures higher than 1900°C. This threshold temperature is by 150°C higher than the melting temperature of Fe2SiO4 at this pressure. The result offers a clue to the genesis of diamond in the deep interior of the earth.
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  • Akimasa MASUDA
    1999 Volume 75 Issue 3 Pages 46-48
    Published: 1999
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    The interesting features that rare-earth elements (REE) exhibit in HCl-HNO3 acid extraction from powdered tholeiitic basalt are reported here. Cerium which can be oxidized to tetravalent shows the highest extraction percentage. The lower extractability of Eu compared with Sm and Gd is attributed to the high chemical resistance of feldspar in which divalent Eu is preferentially incorporated. Based on the extractability, the stable trivalent rare-earth elements, La, Nd, Sm, Gd, Dy, Er, Yb and Lu are divided into three subgroups; {La, Nd}, {Sm}, and {Gd, Dy, Er, Yb, Lu}. This differentiation of the stable trivalent REE is inferred to be related to the polymorphic crystal structures of A-, B- and C-type sesquioxides of REE. Barium shows an extractability identical with that of La-Nd subgroup.
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  • Kensuke NAKA, Masatoshi MIYAMOTO, Yoshiki CHUJO, Takeo SAEGUSA
    1999 Volume 75 Issue 3 Pages 49-53
    Published: 1999
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    The effects of the polarity of various water-immiscible organic solvents on the enzymatic esterification activities of three modified Candida cylindracea lipases, which were prepared by the chemical modification of lipase with poly[(N-acetylimino)ethylene] (2a), poly[(N-propionylimino)ethylene] (2b) and poly[(N-isobutyrylimino)ethylene] (2c), were examined and their enzymatic activities were tried to correlate to the logarithm of the partition coefficient of the solvent between water and 1-octanol (log P). It was found that although the activity increased with increasing the hydrophobicity of the solvent and with increasing the hydrophobicity of the N-substituent of 2, a great rate enhancement of the enzymatic activity was achieved in benzene and toluene by the chemical modification by 2b or 2c, while unmodified lipase and 2a-modified one were almost inactive in them. Moreover, the effect of water concentration in organic solvent was investigated.
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  • Kumiko UI-TEI, Masanari TAKAMIYA, Masatoshi NAGANO, Hidenori SUZUKI, A ...
    1999 Volume 75 Issue 3 Pages 54-58
    Published: 1999
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    We purified a novel substance with survival activity for spinal motoneurons from skeletal muscles of chick embryos. The purification procedure using various column chromatographies was described. The purified substance showed a maximum UV absorbance at 258nm, which suggests that it is non-peptidergic in nature. This is the first report to show that a non-peptidergic substance exhibits the survival activity on spinal motoneurons. A possible candidate for the substance was discussed.
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  • Masanari TAKAMIYA, Kumiko UI-TEI, Masatoshi NAGANO, Hidenori SUZUKI, A ...
    1999 Volume 75 Issue 3 Pages 59-63
    Published: 1999
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    In our preceding paper, we presented the purification of a chick embryo's muscle-derived substance that prevented spinal neurons from undergoing cell death in vitro. In this study, characterization of this substance by 1H-NMR spectroscopic analysis and enzymatic inactivation experiments revealed that the substance responsible for the survival of cultured spinal neurons was RNA. For further characterization a modified purification procedure was devised on the basis of the substance being RNA. The finally purified substance showed λmax at 258nm and prevented enriched populations of spinal motoneurons from undergoing cell death in vitro, in the same way as the crude muscle extract. These results suggested a novel role of RNA as an intercellular signaling molecule.
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  • Masaru TATENO, Hideaki KOIKE, Naoki AMANO, Yuko OHFUKU, Masashi SUZUKI
    1999 Volume 75 Issue 3 Pages 64-69
    Published: 1999
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    The three types of archaebacterial ribosomal RNAs, 5S, 16S, and 23S, have been studied in terms of their closest homologues of the non-archaebacterial origin, the numbers of close homologues of eukaryotic and eubacterial organisms, and the insertion and deletion of bases. It is concluded that all the ribosomal RNAs are of eubacterial-type. In contrast, archaebacterial ribosomal proteins have been identified to compose a population that possesses characteristics of eukaryotic-type. Thus the archaebacterial ribosome is a chimera of the eubacterial-type RNAs and the eukaryotic-type proteins.
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