Netsu Sokutei
Online ISSN : 1884-1899
Print ISSN : 0386-2615
ISSN-L : 0386-2615
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Preface
Forword for Special Issue
  • Kinetic Analysis of the Thermal Decomposition of Inorganic Solids with a Reversible Nature
    Mito Hotta, Nobuyoshi Koga
    2025 Volume 52 Issue 1 Pages 2-10
    Published: January 25, 2025
    Released on J-STAGE: February 28, 2025
    DOIhttps://doi.org/10.11311/jscta.52.1_2
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    Thermal decomposition of inorganic solids with reversible nature exhibits complex behavior because of physico-geometrical constraints. Moreover, its kinetics are significantly influenced by atmospheric and self-generated gaseous products due to the contribution of reverse reactions. Therefore, for universal kinetic analysis for such reactions under various temperature(T) and atmospheric conditions, the fundamental kinetic equation as a function of T and degree of reaction must be extended to consider the effect of partial pressure of gaseous products. To extend the kinetic equation, an accommodation function to explain the changes of kinetic behavior due to the gaseous product, which is expressed as a function of the partial pressure of the gas and the equilibrium partial pressure of the reaction, is introduced. The extended kinetic equation with an accommodation function enables to analyze the kinetic behavior of the reaction universally over different T and partial pressures of the gas. In this paper, the universal kinetic approach to the thermal decomposition of solids with reversible nature, based on the extended kinetic equation, is demonstrated as exemplified by the thermal decomposition of inorganic carbonates, hydroxides, and hydrates. Furthermore, the physicochemical significance of the obtained kinetic parameters is discussed.
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  • Analysis of Enzyme Activity by Isothermal Titration Calorimetry
    Etsuko Katoh, Kazusa Seo, Shun-ichi Kidokoro
    2025 Volume 52 Issue 1 Pages 11-16
    Published: January 25, 2025
    Released on J-STAGE: February 28, 2025
    DOIhttps://doi.org/10.11311/jscta.52.1_11
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    The total time course of the exothermic heat flow of ATP hydrolysis catalyzed by the stable helicase domain derived from tomato mosaic virus replication protein (ToMV-Hel) was monitored by isothermal titration calorimetry (ITC) in 150 mM NaCl, 10 mM MgCl2, 0.5 mM tris(2-carboxyethyl)phosphine plus 100 mM phosphate buffer pH 7.5 at 15 °C. Analysis of the time course of the enzymatic reaction established a method for evaluating competitive inhibition of the product from the initial substrate/product concentration dependence of the apparent Michaelis constant and found that helicase activity is competitively inhibited by the hydrolysis product, ADP. Comparing the true Michaelis constant with the inhibition constant, the enzyme was estimated to have a 17-fold higher affinity for ATP than for ADP under these conditions. We will also present an example of using this method to screen for inhibitors of the ToMV-Hel using the ITC method of evaluating enzyme activity.
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  • Determination of the Thermophysical Properties under Dynamic Process using Temperature Wave Analysis Method
    Meguya Ryu, Junko Morikawa
    2025 Volume 52 Issue 1 Pages 17-23
    Published: January 25, 2025
    Released on J-STAGE: February 28, 2025
    DOIhttps://doi.org/10.11311/jscta.52.1_17
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    Soft materials exhibit excellent flexibility and structural diversity. These characteristics are important for applying soft materials as command thermal systems especially at the microscale. In the structure of soft materials, anisotropy in thermophysical properties such as thermal diffusivity is usually observed, and changes in structure cause changes in macroscopic thermophysical properties. By clarifying the time-dependent changes in thermophysical properties associated with transitions of crystal structures and orientation in molecular systems, it is possible to not only understand the mechanisms of materials as thermal functional media, but also gain fundamental insight into the dynamics of soft materials. Temperatrue wave analysis (TWA) is one of the common methods for determining the thermal diffusivity and thermal effusivity of soft materials. This method enables in-situ measurement of thermophysical properties in dynamical processes by measuring the phase delay and amplitude decay of the thermal response of a sample that is periodically heated. This method is widely applied to microscale transition phenomena, such as phase transitions in liquid crystals and microscale structural transition of soft crystals. This study presents exemplary results of TWA method, with a particular focus on in-situ measurements of thermal diffusivity and thermal effusivity during structural changes. The capability of TWA method analyzing dynamic phenomena in soft material is also discussed. It also discusses the ability of the TWA method to analyse dynamic phenomena in soft materials.
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