Small system thermodynamics is briefly discussed in relation to statistical mechanics and applied to solutions of noninteracting multi component micelles and vesicles. It is shown that the Gibbs-Duhem equation does not hold for the lipid membranes of vesicles as well as for micelles. Polydispersity of micelles and thermal fluctuations of the extensive thermodynamic functions are discussed, and equations of temperature and pressure dependencies of solubilities of surfactants in water are derived.

View full abstract

Microwave spectroscopy that can be applied to study the dielectric relaxation of various fluids under high temperature and pressure has been developed in the frequency range up to 40 GHz. By utilizing this new technique the dielectric relaxation in water has been measured in the temperature and pressure range up to 750°C and 120 MPa, which corresponds to a density range between 0. 05 and 1 g/cm3. The static dielectric constant ε (0) is deduced from the time required for microwave signal to travel through the sample by means of the time domain analysis. The dielectric relaxation time τ is obtained by fitting the experimentally observed microwave transmission rate to the value calculated using the Smatrices on the assumption that the dielectric constant obeys the Debye relaxation. It is concluded that the most relevant parameter determining τ is the temperature at lower temperatures or higher densities, and is the density at higher temperatures or lower densities.

View full abstract

We developed a new method for density measurements under high temperature and high pressure by means of X-ray absorption using a large volume press combined with a synchrotron radiation source. To overcome the variation of the sample thickness under pressure, a sapphire ball or a sapphire ring was used as a calibrant of the thickness. Results on tellurium and bismuth were reviewed.

View full abstract

Static direct transformation of graphitic BC₂N to cubic forms was discussed on the basis of our results of synthetic experiments and characterizations for the products. The graphitic BC₂N was successfully transformed to diamond-like cubic phases at 7. 7 GPa and 2150-2400°C for 15-60 min using a belt-type high-pressure apparatus. Crystallization of cubic B-C-N compound was confirmed in the products obtained at 2300°C by means of XRD and ATEM. The cubic B-C-N, however, was segregated to diamond and cBN with increasing the synthetic temperature to 2400°C, which was also supported by SEM and AES. The formation behavior seems to provide some conceptions to explore new materials by high-pressure synthesis.

View full abstract

Natural pyrope garnets have been transformed at 35-60 GPa by a laser-heated diamond anvil cell (DAC), and the recovered samples were examined with an analytical electron microsoope (AEM). Orthorhombic perovskite was the dominant product phase after the transformation, and the Al content in perovskite increases with pressure and temperature. However, Al-rich perovskite was metastably inverted into the lithium niobate phase during the decompression. The mode of transition behavior of orthorhombic perovskite to the lithium niobate phase varies with the Al content in orthorhombic perovskite. Orthorhombic perovskite with less than 25 mol % Al₂O₃ can be quenched as orthorhombic perovskite after the release of pressure. In contrast, perovskite with about 25-28 mol% Al₂O₃ becomes the alternating lamellae of orthorhombic perovskite and the lithium niobate phases, having the topotactic relation with each other after the decompression. With further increasing the Al₂O₃ content in perovskite, it is completely converted into the lithium niobate phase with polysynthetic twinning on {1012}_hex. From this study, it was proved that, even for Al-rich garnets, the dominant post-garnet phase under the lower mantle condition is orthorhombic perovskite.

View full abstract

The number of patients suffering from food allergies in Japan has recently shown an increace. In addition to egg, milk, and soybean allergies, an increase in cereal allergies from rice, which is the main staple in the Japanese diet, and from wheat is creating important social problems which do not affect just the patient and the patient's family. Accordingly, we would like to discuss the development of low allergenic cooked rice and low allergenic rice bread made from rice which has had the allergens removed by means of high pressure.

View full abstract