Netsu Sokutei

A Study on Dehydration Behavior of CaCrO₄ by the AE and TG-DTA-MS Methods

Yoshiho Ito, Shiro Shimada, Michio Inagaki

1994 Volume 21 Issue 1 Pages 2-6
Published: January 31, 1994
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.21.2

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The dehydration behaviors of CaCrO₄ powders were followed by the AE and TG-DTA-MS methods. TG-DTA-MS mesurements showed that four kinds of waters were contained in the powders, which were released in the temperature regions of 20-145(stage I), 145-230(II), 230-420(III), and 420-620°C(IV). AE signals were generated in three temperature regions of 220-400, 400-620, and 700-900°C, the former two corresponding to the stages III and IV observed on TG-DTA-MS measurements. The particles heated up to 700°C were found to become small in size by SEM, which probably gave rise to AE signals in the stage IV. Up to about 400°C no fracture of particles was observed. It was also found that partial decomposition of CaCrO₄ occurred at about 700°C, which is associated with small AE signals, small weight loss, and traces of lower valent Cr-ions on ESR measurement.

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Measurement of Free and Bound Water During Radish Seed Germination

Effect of Water on Germination of Radish Seed

Yoshinmi Ishihara, Jiro Takano, Satoru Mashimo, Masaichi Yamamura

1994 Volume 21 Issue 1 Pages 7-11
Published: January 31, 1994
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.21.7

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It was found that the water in seeds could be measured as bound and free water, and it was quantitated here by the TDR method.
When radish seeds were dried for 24 hours at 25°C, the water in the seeds suddenly decreased, and when the seeds were dried for 10 hours, the free water decreased more than the bound water, and germination was hardly affected. However if the seeds were dried for over 24 hours, theamount of bound water decreased more than the free water.
In this case, germination of seeds suddenly decreased. Germination was 20%, when the seeds were dried for 96 hours at 45°C, and it was 50% at 25°C.
Therefore both bound and free water are needed for germination, and it is the quantity of bound water which affects the germination of seeds, this can be called the vital water.

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Heat Capacity Measurements Around Incommensurate-Normal Phase Transition of Synthetic Åkermanite Solid Solutions and the Transition Entropies

Tadato Mizota, Kazuaki Iishi

1994 Volume 21 Issue 1 Pages 12-19
Published: January 31, 1994
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.21.12

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Åkermanite solid solution is known as a mineral showing incommensurate to normal (I-N) phase transition at a temperature between 80 and 250°C, which depends on the chemical composition in the substitution series. To clarify the thermal behavior around the transition temperatures, crystals with various chemical compositions were synthesized by the floating zone method and the heat capacities above room temperature were measured by means of a small scale adiabatic calorimeter, using less than 2g of a sample for each measurement. The obtained I-N transition entropy values, about 1.7JK^-1mol^-1 in average, are almost the same, independent of composition and the transition temperature. The transition mechanisms and the value of transition entropy are discussed in terms of a statistical model related to the modulated structure.

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On Heat Capacity of High Temperature Superconductors

Toshizo Fujita

1994 Volume 21 Issue 1 Pages 20-28
Published: January 31, 1994
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.21.20

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After brief summary of typical heat capacity for conventional superconductors, anomalous heat capacity of high-T_c cupurates are reviewed. As compared with conventional superconductors, the cupurates show distinctive features in various aspects. Discussion is addressed especially to the effects of thermal fluctuation at T_c, temperature dependence of heat capacity in connection with symmetry of Cooper Pairs, and anomalies in low-temperature heat capacity.

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Solution Photocalorimeters

Clementina Teixeira, Ingemar Wadsö

1994 Volume 21 Issue 1 Pages 29-39
Published: January 31, 1994
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.21.29

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There exists a wide range of photocalorimetric techniques adapted to different experimental situations and goals. The present article concentrates on instruments used for investigations of solutions and suspensions conducted at ambient temperature range. Basic principles are introduced and different models of photocalorimetric assemblies are discussed. Reported pratical designs are summarized and their properties are compared. The need for use of chemical test and calibration processes is discussed and exemplified.

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Thermal Analysis of Polyhydroxybutyrate and its Copolymers

Hiroshi Mitomo

1994 Volume 21 Issue 1 Pages 40-42
Published: January 31, 1994
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.21.40

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[title in Japanese]

[in Japanese]

1994 Volume 21 Issue 1 Pages 43-44
Published: January 31, 1994
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.21.43

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