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Volume 31 (2004)
- Issue 5 Pages 227-
- Issue 4 Pages 164-
- Issue 3 Pages 100-
- Issue 2 Pages 62-
- Issue 1 Pages 2-
Volume 31, Issue 2
Displaying 1-6 of 6 articles from this issue
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Takayoshi Kimura, Takanori Matsushita, Kenzi Suzuki, Sadao Takagi2004 Volume 31 Issue 2 Pages 62-68
Published: March 30, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSExcess enthalpies of binary mixtures between each of acetonitrile, propionitrile, butyronitrile, pentanenitrile and benzonitrile + methyl methyithiomethyl sulfoxide (MMTSO) and + dimethyl sulfoxide (DMSO) have been determined at 298.15K. All mixtures showed positive enthalpy change over the whole range of mole fractions except acetonitrile + DMSO over 0.95 in mole fraction of DMSO.
Partial molar enthalpies of the mixtures of acetonitrile (1) + DMSO (2) around 0.65 in mole fraction have maximum of HE1 and minimum of HE2. Linear relations are obtained between limiting excess partial molar enthalpies and (μ12μ22)(r1+r2)-6 except the mixtures containing for benzonitrile. However limiting excess partial molar enthalpies of the mixtures of aromoatic compounds + MMTSO or + DMSO showed good relation with (α2μ12+α1μ22)(r1+r2)-6.View full abstractDownload PDF (1210K) -
Yuichi Tozuka, Keiji Yamamoto2004 Volume 31 Issue 2 Pages 69-73
Published: March 30, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSThis review describes the evaluation of molecular state of medicines by using differential scanning calorimetry (DSC). Thermal behavior of amorphous clarithromycin obtained by grinding and spray drying were evaluated. In DSC curves, both broad and sharp peaks for crystallization were observed in 30min ground sample, whereas spray-dried sample showed one broad peak for crystallization. In order to study the physicochemical stability of amorphous cefditoren pivoxil, glass transition accompanying enthalpy relaxation was evaluated for the ground and spray-dried samples by means of modulated-temperature DSC. Glass transition temperature (Tg) and relaxation enthalpy of the ground sample of cefditoren pivoxil were changed by storage for definite intervals at a temperature below Tg, while those of the spray-dried sample indicated an almost constant value by storage. These results suggest that the ground sample was less stable than the spray dried sample. The ground sample might be stabilized by storage below Tg. Thermal behavior of salicylamide in the mixtures with Folded Sheets Mesoporous Materials (FSM)-16 was investigated by DSC. Three kinds of molecular states of salicylamide, i. e., crystalline state, disordered crystalline state for which a broad endothermic peak was observed at a lower temperature, and amorphous state for which no peak on the DSC curves could be observed.View full abstractDownload PDF (1187K) -
Kohsaku Kawakami2004 Volume 31 Issue 2 Pages 74-79
Published: March 30, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSThe use of isothermal microcalorimetry for analyzing structural relaxation and recovery processes of amorphous materials is discussed. Unlike the conventional DSC method, this new method enables to directly monitor the relaxation process. Also featured in this article is its application for investigating the recovery process, which has hardly been reported in literature. The both processes were elucidated using Kohlrausch-Williams-Watts derivative, although its application for the recovery process needs discussion. The relaxation parameters obtained by this procedure agreed very well with those from the DSC method. The advantages and disadvantages of this method are summarized.View full abstractDownload PDF (1200K) -
Yasuo Yoshihashi, Etsuo Yonemochi, Katsuhide Terada2004 Volume 31 Issue 2 Pages 80-86
Published: March 30, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSThis review demonstrated the possibility of application of isothermal microcalorimetry (IMC) for stability evaluation of solid dosage form. Various kinetic equations derived from the different reaction model in the solid state were applied for the obtained data using isothermal microcalorimeter. Suitable decomposition rate constant was successfully derived from the most appropriate kinetic equation evaluated by curve fitting method. Experimental decomposition rate constant of solid dosage form was determined by the time-consuming conventional method, which took more than 6 months. The predicted values were in good agreement with the experimental values. By using this method, the stability of solid dosage form can be predicted by a simple operation in a short time. Application of IMC would be useful for the screening test for the drug stability.View full abstractDownload PDF (1279K) -
Norio Murase2004 Volume 31 Issue 2 Pages 87-92
Published: March 30, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSTo understand the mechanism of ice crystallization during rewarming observed with a frozen crosslinked dextran gel of a certain density of crosslink, DSC, Raman scattering and X ray diffraction-DSC simultaneous measurements were conducted. It was found, as a result, that size of ice crystals as well as freezing behavior depend on the density of crosslink of the gels. By the study of two-dimensional X ray diffraction-DSC simultaneous measurements, formation of small ice crystals was indicated with the gel where ice crystallization during rewarming is observed. Presence of glassy water was also indicated in the frozen state of the gel by the measurement of Raman scattering. Then, it was clarified that ice crystallization in polymer gels is more or less obstructed by the polymer network, and by its change at the time of freezing. From these results together with the knowledge so far obtained, a conceivable mechanism of ice crystallization during rewarming was discussed.View full abstractDownload PDF (1605K) -
2004 Volume 31 Issue 2 Pages 93
Published: March 30, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (145K)
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