The thermodynamic properties and state diagram of the thermally induced aggregation of myoglobin with 1,4-dioxane were determined by DSC, circular dichroism (CD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and density measurements. At a mole fraction (x) of 1,4-dioxane of around 0.10, myoglobin exhibited α-helical aggregation at 25 ºC, which transformed to spherical aggregation without thermal denaturation upon heating. The enthalpy change for the spherical aggregation was −565 kJ mol⁻¹ at x = 0.10, which was numerically greater than that for thermal denaturation of the native state, 428 kJ mol⁻¹, indicating that the aggregate conformation involved many intermolecular interactions. At x = 0.125 – 0.25, the α-helix partially transformed to a β-sheet at 25 ºC, which formed an amorphous aggregate upon heating. The thermal transition depends on the incubation time of the pre-transition state due to conformational changes in this state. The positive change in the partial specific volume of the aggregate indicates a large cavity volume and reduced hydration. On the other hand, the activation volume for the aggregation is negative, (−4.5 ± 1.3) × 10² cm³ mol⁻¹, suggesting that the activated state has a structure with fewer cavities and/or is highly hydrated compared to the pre-transition state, probably due to partial unfolding.

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Methods for the measurement of anaerobic microbial growth are generally complex. Furthermore, aggregation and precipitation make it difficult to estimate bacterial cell counts using turbidity. Recently, we demonstrated that heat evolution is a good indicator of the growth of anaerobic bacteria cultured on soluble carbon sources. In this study, we validated the use of calorimetry to measure growth on insoluble carbon sources using Clostridium spp. When Clostridium cellulovorans and C. thermocellum were cultured on crystalline cellulose, their optical density values over time were irregular. However, the thermograms indicating the heat evolution and the integrated ATP concentrations of the cultures showed highly correlated growth curves. When C. acetobutylicum and C. beijerinckii were cultured on corn starch, peaks were observed at the initial stage based on thermograms and ATP concentration measurements. Thin-layer chromatography revealed that these peaks corresponded to the rapid metabolism of monosaccharides and disaccharides in the culture broth. Thus, the growth of anaerobic microbes cultured on insoluble carbon sources can be measured conveniently and accurately by calorimetry, without confounding effects of aggregation or precipitation. Growth can be measured with high sensitivity, comparable to that of ATP measurements, indicating that calorimetry is a promising method for measuring microbial growth.

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Absorption/desorption property of In-doped BaFeO_3−δ, which are candidates for CO₂ absorbents and oxygen storage materials, was evaluated using thermogravimetry-differential thermal analysis (TG-DTA). X-ray diffraction measurements revealed that the crystal structure changed by 10% In substitution from BaFeO_3−δ with ordered distribution of oxide ion vacancy to cubic perovskite structure with random arrangement of oxide ion vacancy and increase in the average valence of Fe ions. From TG-DTA under CO₂ flow, it was found that the CO₂ absorption property could be controlled by the substitution, indicating that CO₂ absorption property would be tunable to required operating condition. Oxygen desorption behaviour of perovskite BaFe_1−xIn_xO_3−δ was evaluated using TG-DTA under various oxygen partial pressures and iodometry. It was found that the amount of oxygen desorption improved by the substitution, which could be attributed to the random distribution of oxide ion vacancy in the lattice.

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Researches on phospholipid bilayers have importance on various scientific fields such as biophysics, colloidal chemistry and soft matter physics. Investigations on physico-chemical properties of the phospholipid bilayers, e.g., bilayer structure, phase behavior and molecular dynamics, are always essential for these researches. Here, I introduce remaining issues concerning the physico-chemical properties, and our recent approaches to them. In section 1, I simply introduce the phospholipid bilayers and our researches toward the systematic understanding of effects of additives on the bilayers, which has been published in this journal recently. Correlations between hydration states and the phase transitions of the lipids, and the interaction between ions and neutrally charged bilayers are described in section 2 and 3, respectively. Novel working mechanism of the electrostatic double-layer force found from the equilibrium lamellar repeat distance of the bilayers is described in section 4.

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CO₂ absorption property of Li₄SiO₄ was investigated by thermogravimetry under controlled P(CO₂) between 1.0 bar and 2x10-2 bar. By using scanning type TG, equilibrium temperature of chemical reaction described as Li₄SiO₄+CO₂↔Li₂CO₃+Li₂SiO₃ at fixed P(CO₂) could be evaluated. The obtained equilibrium temperature and P(CO₂) by using particle with small diameter showed fair agreement with thermodynamically calculated ones. CO₂ absorption rate increased with increasing temperature or P(CO₂) and decreasing particle size. Under P(CO₂) larger than 0.3 bar, reaction kinetics could be explained with Jander model assuming Li⁺ diffusion as rate determining step. With decreasing P(CO₂) as small as 0.03 bar, it was suggested that reaction model varied to one with surface reaction as rate determining step.

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