In our previous reports, it was shown that applying a DC electric field to an aqueous slurry can enhance the settling of particles. However, the mechanism of the particle settling enhancement by a DC electric field has not been fully elucidated. In this paper, we attempted to elucidate the mechanism by observing enhanced settling phenomena during applying a DC electric field to an aqueous SiO₂ slurry under various conditions, and by measuring particle diameters and pH before and after applying a DC electric field. As a result, it was found that particle settling enhancement phenomena when a DC electric field is applied to an aqueous SiO₂ slurry is caused by the particle-free region formed by electrophoresis, and its moving upward in the slurry due to the density flow generated by the horizontal density difference.

Titanium dioxide (TiO₂) nanoparticles have been used as a cosmetic material for UV protection. Due to their high surface energy, they aggregate particularly under neutral to weakly acidic conditions close to their isoelectric point (5.6). In order to enhance UV protection properties in cosmetic materials, it is important to improve the particle dispersibility under neutral condition. In this study, plasma was generated between the liquid surface of TiO₂ nanoparticle suspension and a needle electrode in the gas phase. As a result, the surface of TiO₂ nanoparticles were coated with amorphous silica by using silicon wafer as an underwater electrode. Since the isoelectric point of the silica-coated TiO₂ nanoparticles was lowered to 4.7, the electrostatic repulsion between the particles was increased under neutral condition resulting in improved particle dispersibility. The silica-coated TiO₂ nanoparticles are expected to be applied to lotions and sunscreens with higher transparency and UV protection.

Prediction of wet granule compression process is significant for the industry. In this study, finite element method (FEM) simulation using the modified density-dependent Drucker-Prager Cap model (mDPC model) is performed to improve the deviation of actual stress values from calculated stress values of wet granules under compression. FEM simulation using the DPC model is also performed as a reference. The results show that the axial stress at the top surface and the radial stress of the wall obtained from the FEM simulation using the mDPC model were more consistent with the experimental values than those obtained by the DPC model.

Solid propellants are widely used as solid fuels for rockets. Composite propellants are solid propellants that consist of oxidizer powders, binder, burning catalyst, metal fuel, and other additives. Propellants with a high burning rate that generate a large quantity of combustion gases in a short period of time are required to realize high-performance rocket motors. Propellants with a low burning rate generate low thrust, and for example, are used as a gas generator for controlling vehicle flight. Therefore, many studies have been focused on the development of propellants with wide range of burning rates. Ammonium perchlorate (AP) and ammonium nitrate (AN) have commonly been used as a propellant oxidizer. The drawbacks of AN are mitigated by the advantages of AP and vice versa, and therefore, the burning characteristics of AN/AP propellants including both AN and AP as oxidizers have been investigated.

Recent advancement in atomic force microscopy (AFM), such as frequency modulation AFM (FM-AFM) and 3D-AFM, has enabled direct imaging of atomic-scale 2D or 3D structures at solid-liquid interfaces. However, application of such high-resolution AFM techniques to nanoparticle (NP) surface analysis is often impeded by the difficulties in fixing NPs onto a substrate. Here, we explain the principle of FM-AFM and 3D-AFM, and typical NP fixation techniques. We also introduce application examples of these techniques such as FM-AFM analysis of photocatalytic TiO₂ NPs and 3D-AFM analysis of antifouling SiO₂ NPs. These examples should highlight the effectiveness of these AFM techniques in NP analysis, leading to the advancement of the AFM applications in powder technology field.

This study presents the enhancement of polymer electrolyte fuel cells through a novel catalyst support Ir-IrO₂/TiO₂, synthesized via flame aerosol process for better durability and performance. With a focus on iridium oxide–titanium oxide particles for their superior properties, the flame process enables efficient production with minimal precious metal use. The research evaluates the influence of iridium loading on particle morphology and conductivity, revealing significant improvements. Specifically, 10 wt% IrO₂-loaded particles drastically reduce volume resistivity compared to pure TiO₂, demonstrating enhanced conductivity. Furthermore, 20 wt% Pt-loaded particles show a high electrochemical surface area with evenly distributed Pt nanoparticles. Membrane electrode assembly tests reveal that the Ir-IrO₂/TiO₂-based anode is comparable to conventional carbon-supported Pt’s performance but offers more excellent stability under high voltage testing, highlighting its potential in fuel cell applications.

Currently, research on zeolites is being conducted in search of new properties. Particular attention is being paid to the nanosizing of zeolites. By nanosizing zeolites, various functional enhancements are expected, such as improved adsorption performance and suppression of catalyst deactivation due to increased surface area. This article describes a new method for preparing nanosized zeolite nanoparticles by milling inexpensive micron-sized zeolite and postmilling recrystallization.