Quark mixings in a subquark model

Quark mixings and theor momentum dependences are discussed in a subquark model in which the weak current is made of the iso-doublet spinor subquarks. The Cabibbo angle is predicted to become larger as momentum transfer between quarks grows up.     

High-energy gravity and the very early universe

It is suggested that gravity may not be asymptotically free at short distances because of the interaction of the graviton with matter. If gravity indeed becomes strong at high energies, a revolutionary change of our present theory on the early universe would seem to be necessary. During the first extremely small fraction of a second in the big-bang universe, gravity would have been so strong that it might not have been described by Einstein's theory of general relativity. The possibility of abnormally strong gravity at high energies or short distances is discussed in some detail. A possible explanation is proposed for the nonvanishing mean baryon number density of the universe. It is also pointed out that the universe may well escape from the catastrophic singularity of Penrose and Hawking.     

Five‐State Molecular Shuttling of a Pair of [2]Rotaxanes: Distinct Outputs in Response to Acid and Base Stimuli

In this study we synthesized two acid‐/base‐controllable [2]rotaxanes featuring aminodiazobenzene and aminocoumarin units, respectively, as chromophores and dibenzo[24]crown‐8 and dibenzo[25]crown‐8 units, respectively, as their macrocyclic components. Each [2]rotaxane contained N‐alkylarylamine (ammonium) and N,N‐dialkylamine (ammonium) centers as binding sites for their crown ether components. The absorption patterns of the chromophores were dependent on the position of the encircling macrocyclic component and the degree of protonation, with three distinct states (under acidic, neutral, and basic conditions) evident for each [2]rotaxane. The mixed [2]rotaxane system displayed stepwise and independent molecular shuttling behavior based on the degree of protonation of the amino groups in response to both the amount and strength of added acids or bases; as such, the system provided five different absorption signals as outputs that could be read using UV/Vis spectroscopy.     

A narrow process window for the preparation of polytypes of microcrystalline silicon carbide thin films by hot-wire CVD method

Effects of deposition conditions on the structure of microcrystalline silicon carbide (μc-SiC) films prepared by hot-wire chemical vapor deposition (hot-wire CVD) method have been investigated. It is found from X-ray diffraction patterns of the film that a diffraction peak from crystallites from hexagonal polytypes of SiC is observed in addition to those of 3 C-SiC crystallites. This result is obtained in the film under a narrow deposition conditions of SiH₃CH₃ gas pressure of 8 Pa, the H₂ gas pressure of 80–300 Pa and the total gas pressure of 40–300 Pa under fixed substrate and filament temperatures employed in this study. Furthermore, the grain size of hexagonal crystallites (about 20 nm) on c-Si substrates becomes larger than that of 3 C-SiC crystallites (about 10 nm) for the films deposited under the total gas pressure of 36–88 Pa. The fact that microcrystalline hexagonal SiC can be deposited under limited deposition conditions could be interpreted in the context of a result for c-SiC polytypes prepared by thermal CVD method.     

Evaluation of microstructures and properties of bulk mesoporous silica

Synthesis of mesoporous MCM-type bulks prepared by hydrothermal hot-pressing (HHP) method using MCM-type mesoporous powder was attempted. Scanning electron microscopy (SEM), bulk density measurement, N₂ adsorption-desorption isotherms and formaldehyde adsorption test have been employed to characterize the bulky products. As a result, we succeeded in preparing a dense and strong mesoporous bulks with high BET over 1000 m²/g through the hydrothermal hot-pressing method under appropriate conditions.     

Structural evaluation and photocatalytic properties of Pt-supported titanate nanotubes

Pt nanocrystal-supported titanate nanotubes as a photocatalyst were prepared by hydrothermal treatment and subsequent heat-treatment in H₂ atmosphere (H₂ reduction) of a mixture of these titanate nanotubes and H₂PtCl₆. TEM results showed that Pt nanoparticles (a few nm in diameter and 5 to 10 nm in length) with good crystallinity were entrapped inside titanate naotubes and were closely precipitated on the surface of titanate nanotubes. These Pt nanocrystal-supported titanate nanotubes possessed the high ability for HCHO decomposition.     

Effects of mixing rules on phase equilibrium calculations

The density dependence in the mixing rule of the cohesion parameter of the cubic equation of state is found not to be necessary in vapour—liquid equilibrium (VLE) calculations. The effects of the functional form and the number of the adjustable parameters of the mixing rules on VLE calculations are examined. It is found that the functional form is less influential in VLE calculations than the number of adjustable parameters and that two adjustable parameters in the mixing rules are sufficient for practical applications.