Transition metal oxides with strong electron correlation show a variety of unusual properties. Establishing the electronic and magnetic phase diagrams as a function of composition and temperature is a first step in understanding their behavior, and sometimes a crucial step in discovering novel properties. This article reviews phase-diagram studies on RCoO₃, RMnO₃, RMn₂O₅, and Y_{2 －x} Bi_xRu₂O₇ (R ＝ rare earth), where heat capacity measurements were instrumental in identifying the phase transitions and understanding the complex properties. High-pressure synthesis and synchrotron powder x-ray structural analysis also played important roles in constructing and understanding the phase diagrams.

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Low-temperature thermodynamic measurements of single crystals of a series of [Mn₄] networked compounds were performed by the thermal relaxation technique and the ac technique. These materials are constructed by chemical linking of single-molecular magnet (SMM) clusters through coordination bonds and have an intermediate character of SMMs and usual bulk magnetic materials. Each cluster possesses an S ＝ 9 ground state with uniaxial anisotropy dominated by D/k_B ＝ －0.4 ～0.5 K. Because of the existence of a superexchange interaction, J/k_B, between neighboring SMMs, the long-range correlations of large and anisotropic spins have been realized. We have also observed a curious magnetic-field-induced glass-like freezing of spin correlations at low temperatures. The extremely sensitive thermodynamic behavior against the magnetic fields and external pressures were observed by the heat capacity measurements under pressures and with magnetic fields.

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Antibodies are widely used for various fields, including identification of targets, molecular imaging, diagnosis, and therapeutics. Fundamental understanding of interactions from thermodynamic viewpoints, based on structural information, is critical for rational design of antigen-specificity and affinity of antibody. Here, we would summarize our recent progresses on thermodynamic analyses of antibody-antigen interactions, and review the molecular mechanism for how an antibody can create the high specificity and affinity for its target, especially form thermodynamic and structural viewpoints.

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Recently, technique of CO₂ separation from exhaust mixture gases is desired as one of countermeasures against the environmental problems. Material used for the separation technique must be compact and can absorb CO₂ quickly. Moreover it must be used repeatedly. From these requirements, Li-Metal oxides (typical example Li₄SiO₄) are regarded as a novel solid CO₂ absorbent. Previously, we have investigated temperature dependence of CO₂ absorption behavior of Li₄SiO₄, and studied on a method to measure reaction rate of CO₂ absorption reaction of Li₄SiO₄ by means of a TG and DTA apparatus with an IR Gold image furnace. Furthermore, we have successfully synthesized new Li-Metal oxides Li₄TiO₄ and Li₂CuO₂, and measured their CO₂ absorption behavior by means of the apparatus and the method. For three kinds of powdered samples (Li₄SiO₄, Li₄TiO₄, and Li₂CuO₂), CO₂ absorption defined by “mass increase per sample gram” were measured by the apparatus when the samples were heated with the heating rate of 5 ℃ min ^－1. up to 1000 ℃ in 100 vol% CO₂ atmosphere. It was found that the maximum CO₂ absorption was measured 36.7 mass%, 42.1 mass%, and 40.2 mass%, respectively for Li₄SiO₄, Li₄TiO₄,and Li₂CuO₂. The maximum CO₂ absorption of the Li₄TiO₄ sample was larger than those of Li₄SiO₄ and Li₂CuO₂. In order to measure rate constant k of CO₂ absorption reaction for three samples, mass increase of the samples was measured with time at a measurement temperature in 100 vol% CO₂ atmosphere. From the results, it was found that, in temperature region of 680 ℃～700 ℃, the rate constant k of the CO₂ absorption for Li₂CuO₂ were almost three times larger than that of Li₄SiO₄ sample.

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