Proceedings of the Japan Academy, Series B
Online ISSN : 1349-2896
Print ISSN : 0386-2208
ISSN-L : 0386-2208
Volume 68, Issue 8
Displaying 1-6 of 6 articles from this issue
  • Hiroshi TAKEDA, Jun SAITO, Takahiro HIROI
    1992 Volume 68 Issue 8 Pages 115-120
    Published: 1992
    Released on J-STAGE: October 13, 2006
    JOURNAL FREE ACCESS
    Five meteorites recovered from Antarctica are unique achondrites with coarse-grained orthopyroxene and olivine crystals and variable amounts of Ni-Fe metal and FeS with additional augite or plagioclase. These mineral species can be found in chondrites, which are the most common types among the observed falls. Both Y74357 and MAC88177 contain considerable augite, but Y74357 is richer in olivine. Y791491 contains minor plagioclase. Discovery of such meteorites with coarse-grained texture and similar major mineral chemistry with extensively modified chondritic bulk chemistries suggest that they are related meteorites with variable amounts of augite and plagioclase and variable degree of reduction. The variability of mineral abundance can be explained by different degree of removal or segregation of partial melts, by a radiogenic internal heating and collisional one. Reflectance spectra of some members of this group combined with those of iron meteorites resemble those of S asteroids common in the main belt. The trend of their variation in mineral assemblage is in line with those of the S asteroids. This model also explains the absence of chondritic asteroids in the main belt, because S asteroids may be modified products of larger chondritic bodies.
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  • Yukio IMANISHI, Shunsaku KIMURA
    1992 Volume 68 Issue 8 Pages 121-126
    Published: 1992
    Released on J-STAGE: October 13, 2006
    JOURNAL FREE ACCESS
    A series of peptides has been synthesized and studied on the conformation, location, molecular orientation, and self-association in phospholipid bilayer membrane. Hydrophobic peptides tend to associate in the membrane of a crystalline state irrespective of the peptide chain length. Hydrophobic α-helical peptides of a chain length corresponding to the membrane thickness formed an aggregate in the membrane of a liquid-crystalline state with the helix axis oriented perpendicularly to the membrane surface. A hydrophobic octapeptide also took a perpendicular orientation predominantly in the membrane by connecting a hydrophilic group, lactose or crown ether, at the C-terminal of the peptide, which provides an amphiphilic property in the primary structure. The peptides taking transmembrane orientation formed a voltage-dependent ion channel. On the other hand, α-helical peptides with secondary amphiphilicity were incorporated at the membrane surface with the helix axis oriented parallel to the membrane. Some peptides with net charge associated at the membrane surface, though the size of aggregate was not large.
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  • Masahiro IRIE, Dawan KUNGWATCHAKUN
    1992 Volume 68 Issue 8 Pages 127-132
    Published: 1992
    Released on J-STAGE: October 13, 2006
    JOURNAL FREE ACCESS
    Poly(N-isopropyla, crylamide) with pendant azobenzene groups was synthesized with the aim of inducing isothermal phase separation of the aqueous polymer solution by photoirradiation. The phase separation temperature Tc of a 1wt% aqueous solution of the copolymer (content of azobenzene units, 2.7mole%) increased from 19.4°C to 26.0°C by UV (350<λ<410nm) irradiation. On standing overnight in the dark, or by visible (λ>470nm) irradiation, Tc again returned to 19.4°C. At 19.5°C, UV irradiation caused the isothermal phase transition from the phase separated to homogeneous state, while visible irradiation induced the phase separation. The maximum phase separation temperature change by UV irradiation was observed for the aqueous solution of the copolymer with 2.7mole% pendant azobenzene units. Below and above the content, the phase separation was not affected by photoirradiation.
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  • Mutsumi KADOYA
    1992 Volume 68 Issue 8 Pages 133-138
    Published: 1992
    Released on J-STAGE: October 13, 2006
    JOURNAL FREE ACCESS
    The equation of the enveloping curves for regional record flood peaks of the form of specific discharge is investigated, logically and verifically. First, the functional form of the equation is examined from the theoretical viewpoint. Next, the parameters contained in the equation are estimated through the heavy rainfall data obtained in a sample river basin. Finally, These equations are synthesized with due consideration of the consistency of the parameters so that they may be applied to almost all rivers in Japan.
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  • Tomoko FUJII, Yuko KUGA, Matsue HORINAKA, Yasuo KUSAMA
    1992 Volume 68 Issue 8 Pages 139-144
    Published: 1992
    Released on J-STAGE: October 13, 2006
    JOURNAL FREE ACCESS
    Effects of thyroid dysfunction on the secretory ability of thyroid C cells (parafollicular cells) were studied in rats. The rats born to mothers thyroidectomized on day 5 of gestation (Tx-F1) were found to have an increased serum thyroxine level and a decreased basal level of serum calcitonin. The calcitonin secretory response to gastrin related peptide (gastrin) was normal in these rats. Neonatal treatment of rats with 0.5 or 2 μg of thyroxine from 2 to 10 days of age (neoT4) resulted in a marked hypothyroid state in adulthood. They showed a significant decrease in the basal serum calcitonin levels and in the calcitonin response to gastrin stimulation. The rats in both groups showed a significant retardation in the body growth and the growth retardation was much greater in the neoT4 rats than in the Tx-F1 rats. The results suggest that the thyroid function alone or together with the thyrotrope function in the pituitary during the fetal life and neonatal period in the rat is important for the functional development of thyroid C cells.
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  • Study of Cholinergic Pathways in the Central Nervous System at Light and Electron Microscopic Level
    Shigeru TSUJI, Ion MOTELICA-HEINO, Marie-Jeanne BRISORGUEIL, Philippe ...
    1992 Volume 68 Issue 8 Pages 145-149
    Published: 1992
    Released on J-STAGE: October 13, 2006
    JOURNAL FREE ACCESS
    Immunocytochemistry of choline-acetyltransferase (ChAT) has been combined with autoradiography of [3H]choline after retrograde axonal transport on the same tissue section. This combination was performed with efficient preservation, in situ, of [3H]choline or its derivatives by ionic fixation with silicotungstic acid. The cholinergic neuronal pathway from the diagonal band of Broca (DBB) of basal forebrain to the olfactory bulb (OB) was investigated with this method. After the injection of [3H]choline into the OB, radiolabelled neurons were identified in the DBB. Most of them were ChAT immunoreactive confirming the specificity of [3H]choline retrograde labelling for cholinegic neurons. At the electron microscopic level, silver grains could be observed only on the cytoplasm. This method will be useful to study the coexistence of transmitters in the cholinergic pathways and at the same time to determine the chemical nature of the afferences making contact with a defined soma of a cholinergic pathway.
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