Several research groups including us had reported that catalytic particles with asymmetric composition or morphology exhibit autonomous motions in a homogeneous solution containing reactant. In this study, we provide asymmetric environment where unsteady or quasi-steady gradient of a reactant (ethanol) is formed, although we use spherical catalytic particles made of single metal (Pt). As a result, we found that even spherical particles exhibit specific motility, chemotaxis that objects move along concentration gradient of specific chemical species. In our system, Pt catalytic particles show translation toward the area with higher concentrated reactant (ethanol). Such a new phenomenon is expected to apply to chemical systems such as power source of micromotors and catalytic reaction systems with high reaction efficiency, due to particles’ motility.

Mechanochemical polymerization of methyl methacrylate (MMA) monomer was carried out by grinding alumina powder that had high thermal conductivity. A planetary ball mill with high grinding ability was used because alumina has high hardness. The experiments were conducted using different monomer concentrations and different types of solvents. In addition, the effects of grinding conditions on the fineness of alumina particles and the amount of generated polymer were examined. It was found that the amount of polymer could be controlled by the MMA concentration and that the rate of mechanochemical polymerization was highest in aqueous solution. The polymerization occurred in alcohol solvents, but to a limited extent because of inhibition of radical initiation.

DEM simulation of wet granulation has been performed by applying population balance in most cases found in the literature. From the point of view of industry, DEM simulation based on force balance in required for discussing the effects of the amount of binder, spray characteristics, and so on. This paper proposes new idea of capillary force model, considering non-slip boundary condition between particles and particle/wall, called “Non-slip capillary force model.” In this model, capillary forces work between interacting points, which are generated on the surface of particle when capillary is created between particles, and the interacting points are fixed on the surface of particles, meaning that the position of the interacting point changes according to rotational motions of particles. This force model is applied to the two systems: 1) collision of an aggregate against wall, and 2) wet granular system. The following results are achieved through the research: a) aggregates are generated with non-slip capillary force model and the aggregate shows properties of rigid body, b) the aggregate can be broken, when the collision force is over the capillary force. From these results, it can be expected that “Non-slip capillary force model” is inevitable for DEM simulation for wet granulation process.

A numerical calculation method of the fluidized bed calciner for cement production including pulverized coal combustion, raw material decarbonation reaction and heat transfer was developed using the coupling simulation method of DEM - CFD (Discrete Element Method - Computational Fluid Dynamics). In addition, in order to shorten the calculation time, a coarse-grained model for DEM was used in the DEM-CFD. Based on this, the influence of the position and the number of pulverized coal blowing lines into the calciner on the characteristics of pulverized coal combustion and the property of raw material decarbonation was investigated. As a result, a modification plan to change pulverized coal blowing lines to promote pulverized coal combustion and raw material decarbonation was found from the calculation results, and the position and the number of pulverized coal blowing lines were changed from a single pulverized coal blowing line to two blowing lines in a commercial manufacture system. Then, the modified effectiveness and the validity of the numerical calculation method were verified by measuring actual gas composition and temperature distribution in the calciner before and after modifying.

Composite propellant is fuel for solid rocket and consists of a large amount of powdered oxidizer held together in a matrix of binder. Various kinds of oxidizers have been used for propellant ingredients to manufacture the propellants with wide burning rate range for various applications. Now, ammonium perchlorate has been widely used as an oxidizer and many reports on the burning characteristics of the AP-based propellant (AP) have been published to date. Recently the burning characteristics of the propellants prepared with ammonium nitrate and nitramine have been investigated. This review gives the influences of particle properties of these oxidizers on the burning rate characteristics of composite propellants.

Recently, ferroelectrics with relatively small bandgap energy have been receiving much attention because of the characteristic photoinduced electrical responses under visible light irradiation. However, such photoresponsive materials have serious problems such as poor photoelectric conversion properties, especially low photocurrent. It revealed that incorporation of silver (Ag) nanoparticles in the film as a surface plasmon excitation agent is effective to enhance photocurrent of narrow bandgap ferroelectric (such as BiFeO₃) thin films. The synthesized BiFeO₃ and Ag nanoparticle/BiFeO₃ thin films demonstrated rapid on/off responses of photocurrent to visible light. The Ag nanoparticle-embedded BiFeO₃ film exhibited a several times higher photocurrent than the BiFeO₃ film.