Lubricants are an important material in the production of tablets in industrial scale by compression because they supress adhesion to punches and die and inprove powder flowability during compression. Although insoluble material, such as magnesium stearate, is the most popular lubricant for practical use, we applied a soluble material: sodium lauryl sulfate (SLS) to direct compression method as a lubricant, and investigated the effect of humidity on the tableting compression properties. Spray-dried SLS (S-SLS) and recrystallized SLS (R-SLS) were used as lubricants. Physicochemical properties of S-SLS were significantly different from those of R-SLS. R-SLS absorbed water at a relative humidity (RH) higher than 20% at 25°C, whereas the water adsorption of S-SLS occured at a RH higher than 60%. The bulk powder for tableting compression test was prepared by mixing spray-dried lactose and 0.1% SLS. The compression and ejection processes were evaluated by measuring compression and ejection energy during tableting process. The tableting compression processes of S-SLS and R-SLS were not affected by the storage humidity of SLS. The tablet ejection energy of wetted S-SLS was significantly lower than that of dried S-SLS, but those of R-SLS were almost the same.

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The role of various nonionic surfactants on the adhesive force between a mica plate and a SiO₂-surface in moist cyclohexane are investigated using an atomic force microscope (AFM). It is found that the adhesive force decreases with increasing concentration of surfactants and also with the value of Hydrophile-Lipophile Balance (HLB), and that the hydrophilic surfactant with the highest HLB, polyoxyethylene dodecylether (C12E9), has nearly the same ability in the reduction of adhesion as the ionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate (AOT). However, it is estimated that different mechanisms are involved for these surfactants; in the case of AOT, water is removed from the surface because water is dissolved as micelles with AOT, but, in the case of C12E9, water is not only solubilized but also captured by C12E9 with the long hydrophilic chain on the surface so that sufficient water cannot be supplied for bridging.

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Surface modified alumina powder having photocatalytic activity was studied. In order to control the amount of Ti introduced on the surface at the molecular level, the powder was prepared by chemical surface modification with a monofunctional titanate-based coupling agent, followed by partial oxidation of the modification group. The surface density of Ti introduced onto the surface was quantitatively increased with the concentration of the modifying reagent, and/or the repeat times of the modification. Furthermore, the relationship between the surface structure and the photocatalytic activity was discussed. The surface structure was measured by XPS and UV-Visible absorption spectrometry. The photocatalytic activity was determined by means of the degradation of Methylene Blue molecule in a water solution with UV irradiation. The photocatalytic activity appeared at the Ti surface density of 3.7nm^-2. The optical absorption edge in UV of the sample shifted to long wavelenghts. The ability as a photocatalyst increased with the amount of Ti-O-Ti. It was recognized that the photocatalytic activity was related to the amount of Ti-O-Ti on alumina surface and the ability of UV absorption.

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