Cellulose is the most abundant bio-renewable resource on the earth. However, the extent of its application is limited due to its inefficient dissolution in common solvents. In this study, we focused tetra-n-butylphosphonium hydroxide solution（［TBP］［OH］，40％ aqueous solution） as the solvent for cellulose epoxidation reaction and film preparation through crosslinking reaction. In the results of reaction, we succeeded in preparing epoxidized cellulose with a degree of substitution value of 0.15 to 1.67. The cellulose film crosslinked by reaction of epoxy groups showed higher transmittance in comparison with the no crosslinked cellulose film. The elastic modulus of the crosslinked cellulose film was 7.7 GPa, which was 1.2 times higher than that of the cellulose film without crosslinks.

Wood is attracting attention as an environmentally friendly material in terms of carbon fixation. Therefore, wood material market is also increasing and demands are higher. Especially, surficial uses are increasing, such as car interior, cell phone casing, lump shade and so on. In its application, appearance is particularly important property because it directly affects sales. Against this background, optical transparency wood has recently attracted a lot of attention. It is generally assumed that the denser the wood, the more it absorbs light and hence the less optical transparency it tends to be. However, this could not always be explained well by the density dependence of transparency of wood. Recently, it has become clear that the diffusion on the interface internally structure of material, taking into account not only the absorption of the cell wall but also the cell structure, is important for the transparency of wood. It is shown that the light diffusion can be described by a simple Fresnel’s equation.The transmission and reflection values on the interface are determined by the relationship between the refractive indexes of the cell wall and that of the air. Using this property, the authors have developed a processing technique for the wood that transmits light only in arbitrary areas. In this review, the hierarchical structure of wood required for the development of this processing technique is described, and the insights into the design of wood gained in the course of the development of this technique are also presented.

Reaction controls of silane coupling agent （SCA） for the increase of chemisorption and the formation of self-assembled monolayer （SAM） were reviewed. When the silica particles treated with SCA are heated to accelerate the chemisorption reaction, evaporation of monomer-like SCA and the chemisorption reaction take place simultaneously. The oligomer formation in the SCA-treated layer or using the oligomer-type SCA and the SCA with long organic chain was useful restrained the evaporation and increased the chemisorption effectively. The control of amount of moisture was most important for the formation of orderly SAM. Using the chlorosilane without hydrolysis was also useful. Usually, the reaction of SCA needs hydrolysis. However, the alkoxy group in SCA can reacts with the silanol group on silica surface without hydrolysis at higher temperature. The first principles calculation is useful for the analysis of the reaction of SCA by the comparison with experimental result.