Continuous wet granulation using a twin-screw granulator has attracted much interest in the pharmaceutical industry. The physical properties of granules prepared through the twin-screw granulation process depend on the several factors, such as screw and barrel geometries, operating conditions, and formulations of raw materials. In particular, it is known that the fill level in a twin-screw granulator and the binder additive ratio have an impact on the twin-screw granulation process. In this study, mutual effects of the two major factors on the granulation process was investigated experimentally and numerically. By combining the experimental and numerical analyses, a prediction model of the granule growth rate was proposed. The proposed model demonstrated that the granule growth rate was determined by the total energies (compressive and shear directions) and the index of granulation.

The corrosion resistance of stainless steel comes from the passive film. Surface modifications can enhance the resistance and bring about new functions. Here in this report, a novel approach for in-situ measuring the thickness of passive film in solution was first introduced. Next, a mop electrolytic fluorine treatment was used to improve the corrosion resistance. Then, ultrasound was applied to suppress both the pitting corrosion’s initiation and growth. Finally, a rough surface was produced and then the deposition of a PFDS or PE film was used to produce hydrophobicity. The corrosion behavior of such hydrophobic surfaces was confirmed.

Electroless displacement deposition on silicon is a facile wet process, i.e. immersing silicon substrates or silicon powder into a simple metal salt solution including hydrofluoric acid. It can selectively deposit noble metal and copper nanoparticles onto silicon. The size and distribution density of nanoparticles depend on the surface conditions of silicon and deposition conditions. The deposited nanoparticles can work as effective catalysts on silicon, such as solar to chemical conversion using photoelectrochemical cells, autocatalytic electroless deposition of adhesive metal films, and metal-assisted etching. The etching can produce porous silicon and silicon nanohole arrays, which act as optical antireflection thin films.

Silica materials have been practically used in various fields. In this paper the evaluation methods of silica surface are discussed, especially focusing the surface hydroxyl groups which play the important roles of surface and interface phenomena. Previously reported estimation methods were summarized. New information about the two-dimensional distribution of surface hydroxyls and the structure of hydrogen-bonded hydroxyls using the probe molecules was reported. The surface properties of crystal silicas were investigated. Lastly the origin of hydroxylation by the cleavage of surface siloxane bonds with water adsorption was discussed from the standpoint of the rings of SiO₄ tetrahedra unit.

Surface modification by coating ceramic layers can add new functionality to substrate materials or can protect substrate materials from harsh environments. Materials design in surface modification will be greatly enhanced by precise and careful control of crystal orientation and microstructure in the ceramic coatings. Chemical vapor deposition (CVD) is a versatile coating method with excellent controllability of crystal orientation and microstructure by deposition conditions and conformal step coverage on not only wafer substrate with processed surface but powder or fiber substances. This article introduces self-oriented growth and epitaxial growth as methods for controlling crystal orientation and microstructure in CVD process, and novel self-organized phenomena with ordered structure in ceramic eutectic systems via CVD process.

XAFS is a fine structure that appears after the absorption edge of the X-ray absorption spectrum, and is known to reflect the local structure and electronic state of X-ray absorbing atoms. XAFS is an extremely powerful method for structural analysis of materials without crystallinity, and is currently widely used for the characterization of nanoparticles, catalytically active species, and trace elements in glasses. In this review, I briefly explain the principle and measurement method of XAFS, and introduce examples of its application to heterogeneous solid powder catalysts and metal nanoclusters, centering on the author's research results.