All issues
Volume 14 (1987)
- Issue 4 Pages 133-
- Issue 3 Pages 95-
- Issue 2 Pages 51-
- Issue 1 Pages 2-
Volume 14, Issue 2
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kayo Adachi, Michihiko Momota, Takashi Wakabayashi1987 Volume 14 Issue 2 Pages 51-57
Published: April 20, 1987
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSPhysicochemical properties of rat liver mitochondrial membranes have been studied using differential scanning calorimetry (DSC). Exothermic and endothermic lipid phase transition temperatures of mitochondria were detected at -10.5°C and -4.6°C, respectively. Lipid phase transition temperatures of the outer and inner membrane fractions were almost the same although their membrane compositions were different from each other. Mitochondrial lipids free from cholesterol have revealed two distinct, broadened peaks suggesting that cholesterol plays a key role in the cooperativity of membrane lipids protecting them from phase separations.
There were practically no differences in lipid phase transition temperatures between intact mitochondria and their extracted lipid fraction. However, fluorimetric analysis of the latter revealed an increase in the membrane fluidity. Effects of Ca2+, freezing-thawing and ethylene glycol on the physicochemical properties of mitochondrial membranes were also investigated.
The present results suggest that DSC is a useful tool for the study of physicochemical properties of the mitochondrial membranes, but analysis of the data obtained by DSC should be made in the light of those obtained by other methods such as fluorimetry, ESR and NMR.View full abstractDownload PDF (1326K) -
Jun Magoshi, Shigeo Nakamura1987 Volume 14 Issue 2 Pages 58-69
Published: April 20, 1987
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSRecent topics on the structure and thermal properties of silk fibroin and sericin, which are two major components of silk filament, are reviewed. Emphasis has been placed to the crystal modification and the conformational changes of silk fibroin as a function of temperature, as well as the phase transition behavior such as the glass transition and crystallization.
Three conformations, α form, β form and random coil have been found for domestic silk fibroin. Specimens with these conformations are obtained from aqueous solution by varying casting conditions such as the initial fibroin concentration and the temperatures of casting and quenching. The α and β crystals are stable to heating. However, random coil conformation is converted to the α and β forms by various treatments.
When the α and β crystals are heated, water is evaporated up to about 100°C and the molecular motions in the crystal regions starts at about 175°C. The α→β transition is induced thermally at 270°C.
As amorphous silk fibroin with random coil conformation is heated, water is evaporated up to about 100°C, and intra- and intermolecular hydrogen bonds are broken between 150 and 180°C. The glass transition of fibroin is observed at 173°C. The random coil→β-form transition accompanied by reformation of hydrogen bonds takes place above 180°C, followed by crystallization to the β form crystals starting at about 190°C.
The glass transition of sericin occurs at 170°C and the crystallization takes place at 205°C. The glass transition temperatures of wild silk fibroin are observed from 160 to 210°C depending on the species of silkworms.View full abstractDownload PDF (1727K) -
Hiroshi Nouda1987 Volume 14 Issue 2 Pages 70-77
Published: April 20, 1987
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSThis paper concerns thermomechanical analysis (TMA) on poly (ethylene terephthalate) (PET) films, in relation with their application to floppy disk base. When environmental conditions of data retrieval from a floppy disk are different from those of data recording, off-track of the head on the floppy disk occurs, and the extent of off-track can be estimated by using the TMA data. Both the linear thermal and linear hygroscopic expansion coefficients of PET films depend on the direction of their manufacture. The anisotropy (i. e., direction dependence) of those coefficients usually get higher as the position of the measurement gets closer to the widthwise edge of PET film manufacturing process. The extent of off-track increases with increase of the anisotropy.View full abstractDownload PDF (908K) -
1987 Volume 14 Issue 2 Pages 77
Published: April 20, 1987
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (150K) -
Naoyoshi Inouchi1987 Volume 14 Issue 2 Pages 78-82
Published: April 20, 1987
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (561K) -
S. Ito1987 Volume 14 Issue 2 Pages 83-86
Published: April 20, 1987
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (533K)
- |<
- <
- 1
- >
- >|