In the vacuum system of pneumatic transport, the authors have proposed, that a suction nozzle equipped with an injection pipe at the center, would provide a highly-dense therefore a highly-efficient method of transporting a powder. In this paper, we examine the effect of nozzle length, the inserted depth of the suction nozzle into the powder bed. The resulting data show that the nozzle performance improved in a range of lower nozzle depths, but saturated in a range of higher nozzle depths with no insertion length of injection pipe. The powder behavior near the suction nozzle at different nozzle depths was observed with powder flow visualization.

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In wet shaping, the amount of dispersant added to the slurry is a crucial factor in producing high-quality ceramic products. Many researchers have investigated the amount of dispersant that adsorbs to slurry particles. However, few studies have examined how the solid concentration of slurry affects the amount of adsorbed dispersant. In our previous work, we measured the amount of adsorbed dispersant at various solid concentrations and addition amounts of dispersant. In the present work, alumina particles containing magnesium as a sintering aid were used. The conformation of polyelectrolyte dispersant was changed by magnesium ions, and the adsorption isotherm showed a local maximum. In the case of laurate, some molecules remained in solution and did not adsorb to particles because of its thermal motion and few adsorbing sites. Consequently, the amount of adsorbed dispersant was affected by the diffusion of magnesium from the particles, the molecular weight of the dispersant, and the solid concentration of the slurry.

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The effect of post-synthesis process, such as washing and drying of nanoparticles, on their redispersion behavior in solvents were investigated by using TiO₂ nanoparticles (c.a.5 nm) modified with oleyl phosphate (TiO₂-OP). The washing process conducted in this article was dispersion of TiO₂-OP in toluene and collection by centrifugation after flocculating the particles by adding poor solvent. When TiO₂-OP cake was simply vacuum dried after washing, the average size after their redispersion with ultra-sonication in toluene was c.a. 40 nm. It was found that this average size gradually reduces to 20 nm by settling the suspension. Contrary, when TiO₂-OP was dried by evaporating the solvent after dispersing the cake in toluene, their average size in toluene easily reduced to 20 nm just after treating ultra-sonication. The behavior of these differently dried TiO₂-OP during redispersion process in toluene is discussed based on the structure of ligands and particle interactions in toluene.

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A nanoparticle aerosol charging is one of the most important nanotechnologies because only Coulombic force working on charged particles in an external electric field can control motions of nanoparticles in gas phase. Recent studies on nanoparticle aerosol charging are reviewed. For bipolar charging, three chargers developed by Lee et al., Kwon et al. and Kimoto et al. are explained. For unipolar charging, five chargers developed by Chen and Pui, Hernandez-Sierra et al., Han et al., Kwon et al. and Kimoto et al. are described.

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Solid production at the interface of two phases is an effective way to produce materials with hollow structure. This review paper will introduce our new fabrication method of TiO₂ hollow particles, in which sprayed water droplets were introduced into a solution of titanium alkoxide, inducing the rapid sol-gel reaction of titanium alkoxide at the interface of water droplet and organic phase. This strategy was also applied to the production of TiO₂ hollow fibers and core-shell composite fibers by electrospinning an aqueous solution of polymer instead of spraying water.

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