The purpose of this study is to investigate the effects of acoustic streaming and acoustic radiation force on particles motion in an ultrasonic standing wave. A flexural vibration plate with 4 nodes was designed, and it was shown that the amplitude at the antinode is proportional to the voltage. This means it is possible to conduct experiments with any amplitude. After confirming that a standing wave field was generated in closed space, an experiment was carried out to visualize acoustic streaming. Eight vortices were observed in the horizontal direction, indicating a Rayleigh acoustic flow. In addition, a vortex in perpendicular direction against the plate was generated when the height between vibration plate and acrylic surface was set at half wavelength. Then two vortexes were obtained at a wave length for the height. Simulations for acoustic pressure and streaming agreed with this experimental result. Finally, simulations on particle motion showed that acoustic flow dominates when particle diameter is less than 20 μm. On the other hand, the motion of over 20 μm particle is influenced by acoustic radiation force.

This review presents new techniques for the measurement of ceramic slurries. First, we have developed a scanning electron-assisted dielectric microscope (SE-ADM) system with energy-dispersive X-ray spectrometry (EDS) that enables direct observation and elemental analysis of nanoparticles in solution. This system facilitates the understanding of alumina particle dispersion states in solution, binder distribution, and silica and magnesium particle bonding states. Furthermore, we demonstrate a dynamic approach to evaluate adsorptive interactions between ceramic particles and polymeric binders entangled in a slurry by utilizing differential centrifugal sedimentation (DCS). The settling of particles under a centrifugal force field exerts significant viscous resistance on the adsorbed binder, leading to its detachment, influenced by particle size and density. This behavior directly reflects the particle-binder interactions, and detailed DCS spectrum analysis enables the quantitative assessment of nano-Newton-order adsorption forces.

Calcium carbonate nanoparticles are widely used in various composite materials across industrial sectors. However, previously synthesized calcite nanoparticles have typically been rhombohedral with an aspect ratio of ~1. This study investigates the microscopic evolutions of particle morphologies during the formation of calcite rhombohedral nanoparticles. By better understanding these changes, methods involving the addition of Ca(OH)₂ and Mg(OH)₂ have been developed to produce high-aspect-ratio 1D chain-like particles. Controlling the primary particle morphology significantly enhances solid-liquid separation in slurries after liquid-phase synthesis and improves the mechanical properties when these particles are used as fillers in composite materials.

The flexible metal-organic frameworks (MOFs), which are a new type of porous material, exhibit unique adsorption behavior, and are expected to have a wide range of applications. However, to overcome the issue of low handling performance of flexible MOFs, it is necessary to establish a molding process. Although it is predicted that the flexible MOF particles and their aggregate structure should strongly affect the molding process, the effect on the particularly unique adsorption behavior is still unknown. In this study, the effect of the aggregate structure of flexible MOF particles on the uniaxial compression process was investigated experimentally and numerically. It was demonstrated that hollow-structured aggregates maintained the best adsorption properties. In addition, numerical analysis revealed that the force applied to the particles was reduced in hollow-structured aggregates. These would be useful results for the practical application of flexible MOF particles.

Cerium oxide nanoparticles were synthesized using the Forced Thin-Film Type Reactor (FTFR). The precipitation solution was changed from aqueous sodium hydroxide to ammonia solutions. By adjusting the mixing ratio of trivalent and tetravalent cerium ions in the solutions and varying the cerium ion concentration, the shape of the particles varied from spherical to truncated octahedron and irregular shape to cuboidal to truncated octahedral. It was estimated that the change in particle shape could be attributed to the difference in the concentration of dissolved oxygen and hydroxide ion in each solution.

Nanoemulsions have been employed as one of the methods for nano-dispersing poorly water-soluble drugs in mucus. However, most liquid suspension such as the emulsions is washed by the clearance effect on the mucus surface. This study examined the spontaneous emulsification formulation using porous polymer microparticles with mucosal adhesion as the technology for drug permeation enhancement. The nanoemulsion formation expected in this technology could be realized using medium-chain fatty acid triglyceride as the oil component. Moreover, the spontaneous emulsification and the diffusion of the nanoemulsion in mucus proceeded smoothly by using porous particles composed of anionic polymers that have little interaction with mucus components, because mucus is composed of anionic polymer, mucin. It was anticipated that the fine emulsions prepared by this method would enhance drug transport in mucus.

Flowability of wet granules is an important indicator for design and control of manufacturing processes. In this study, we aimed to develop a method to evaluate the flowability with simple equipment and operation. We measured the stirring torque under constant normal stress and the resistance force acting on the plate penetrating into the granules layer. The stirring operation did not properly measure the flowability of strongly cohesive wet granules because voids around the stirring impeller were generated. The penetration operation was able to evaluate the flowability over a wide range of water content conditions by two different indices. Furthermore, the theory of bearing capacity was applied to the penetration tests.

Our study described a new annealing approach for dry-coated formulations, which includes heating of the dosage forms in plasticizer vapor. First, coated tablets were produced by V-shaped blending of tablets and polymer particles without any solvents. Second, these tablets were placed in a desiccator, in which triethyl citrate in liquid state was pre-charged, followed by heating at various temperatures. The resulting tablets were characterized. The polymer particles layered on the surface of tablets coalesced by heating at 80°C or more in plasticizer vapor, indicating that using plasticizer vapor could lower heating temperature required for film formation of coated polymer. The weight of polymer compacts increased by heating in plasticizer vapor as heating temperature increased. These data were correlated with vaporization rate of the plasticizer, indicating that plasticizer in gas state was absorbed in polymer particles, promoting film formation due to a decrease in glass transition temperature of the polymer.

In this study, core-shell type particles with a membrane-like shell layer were prepared using a planetary ball mill. Tg = 63°C particles (8.7 μm) and Tg = 32°C particles (7.4 μm) containing a low melting point material were used for the core particles, and water suspension of acrylic particles (150 nm) were used for the shell material. Cross-sectional observation showed a membrane-like shell layer with no visible interfaces was produced on the core surface. This is because the shell particles uniformly adhered to the core particle surface, followed by the close packing and deformation due to the capillary force and curing during the vacuum drying. When the processed particles were heated in an oven at the temperature of the Tg of processed particles, no thermal aggregation and seepage of the low melting point material were observed. It was found that the shell layer effectively protected the core particles.

Hollow particles are widely used because they have different properties from solid particles, such as low density and high specific surface area. Here, we investigated the effects of the presence or absence of ultrasound irradiation and the amount of ammonia added in the synthesis process of hollow silica particles using calcite nanoparticles as a template. As a result, particles with thicker shells, higher particle density, and smaller specific surface area and pore volume can be synthesized by stirring with a stirrer while being irradiated with ultrasonic waves than by stirring with a stirrer alone. Furthermore, by increasing the amount of ammonia added, particles with thick shells can be synthesized.

The aggregation and dispersion structures of surface-modified nanoparticles in a solvent were visualized and analyzed using numerical simulations based on the discrete element method that takes into account the interaction between the surface-modifier and organic solvent. The interface structure between the surface-modifier and organic solvent was visualized using molecular dynamics simulations. The relationship between the interface structure and their affinity was analyzed.

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.

In this study, basic research was conducted to develop numerical models for filling behavior, compaction process, and tensile test of compacts. Numerical calculations of the filling behavior using distinct element method were performed. The calculated results got a good agreement with experimental one, enabling us to perform the numerical analysis of the filling process. The powder compaction process was also performed using multi particle finite element method (MP-FEM) with the information on the particle position and radius obtained from the DEM calculations. The compaction pressures of the same order as the experimental results were obtained, suggesting that the powder compaction process was successfully analyzed numerically. Furthermore, using the compact geometry obtained from the compaction calculations, tensile tests were numerically calculated using the MP-FEM when a load was applied in the radial direction of the compact. The crushing process of the powder layer was successfully represented. It was shown that the tensile strength can be calculated from the numerical analysis. The particle filling behavior using DEM and the compaction and crushing processes using MP-FEM were successfully calculated numerically in a series.

It was introduced a test example in which a jet mill line was automatically controlled using an online particle size analyzer, and also introduced sampling example from multiple process lines. In a jet mill line, an online particle size analyzer was installed at the mill outlet, and the raw material feed rate was feedback-controlled based on the measured particle size. The particle size of the mill product could be controlled with a delay of about 2 minutes. An example of sampling from two lines revealed that it is possible to perform sampling that responds instantaneously to line switching without contamination.

The grinding of medical tablets is generally discouraged due to stability issues and various other issues. However, in specific scenarios directed by doctors, pharmacists may engage in grinding medical tablets, particularly to cater to pediatric or dysphagia patient populations as extra-label use. In the case of ground film-coated tablets, many film fragments arise in ground powder. Hence, the determination of the grinding endpoint for film-coated tablets is more challenging compared to uncoated tablets. The reports about grinding efficiency are limited because of the assumption that film-coated tablets are taken as tablets. The purpose of this report is to clarify how pharmaceutical excipients, particularly cellulose derivatives, utilized in film coating influence the grinding efficiency of film-coated tablets. Preliminary findings from the grinding of ten medical commercial tablets suggest that a higher concentration of hydroxypropyl methylcellulose (HPMC) correlated with increased difficulty in grinding film-coated tablets. Four film coating solutions with different HPMC-based components were used to coat model tablets prepared by the authors and their grindability was evaluated. The grinding of these film-coated tablets investigated those higher concentrations of HPMC resulted in increased tablet strength and larger residual film fragments. Moreover, the introduction of small quantities of additional plasticizer to the HPMC solution was found to decrease film strength, making the tablets more amenable to grind. It was shown that the components in the film coating solution affected the mechanical properties of the film and also the grinding characteristics of FC tablets.

The simulation using the Advanced Discrete Element Method-Computational Fluid Dynamics (ADEM-CFD) model analyzed the motion and breakage behavior of particles during wet ball milling in order to investigate the effects of the collision velocity and angle between two grinding balls on the particle grinding behavior. The analyses showed that the particles were more damaged when the grinding balls collided with a faster collision velocity in closer to a normal collision direction. The degree of the particle damage was quantified by the release energy, which was defined with the potential energy released by breaking the internal bonds of the particles. The release energy was strongly related to the normal components of the impact energy calculated from the collision velocity between two grinding balls.

Sessile organisms cause significant economic losses on submerged artificial surfaces such as ships. The use of tributyltin (TBT)-based antifouling paint for underwater ship hulls was banned due to its high toxicity to marine organisms. Therefore, it is necessary to develop low environmental impact antifouling technologies. Previously, antifouling studies focusing on the physiological and ecological understanding of fouling organisms has been conducted. And antifouling materials inspired by surface properties of marine organisms were developed in recent years. This review introduces the settlement selectivity and behavior of barnacle cypris larvae on the surfaces with different surface properties, such as micro-structures and functional groups.

Powder compression is the process of obtaining pellets by directly applying pressure to powder beds. The densification phenomenon involving the plastic deformation of particles is still unclear. In this study, the powder compression process of the binary mixture of powder with different plasticity was calculated by using the discrete element method incorporating Edinburgh elasto-plastic adhesion model. The macroscopic and microscopic powder properties were evaluated in the conditions of different volume fraction plastic powders. The calculation method of contact plasticity between elastic and plastic particles, which was proposed in this study, was validated by the data of experimental comparison tests. The result of this study indicated that particle plasticity strongly affected the powder properties, especially contact area inside the powder bed. We hope that this study will be useful for applications where the contact area inside the powder bed is important, such as batteries.

Using a horizontal batch dry bead mill newly developed by our company, talc raw material was ground in air, and its grinding performance and mechanochemical effect on the sample were evaluated from various perspectives. First, the average diameter of the ground product as a grinding performance decreases with the increase in grinding time or power source unit, reaching the submicron size. In addition, when mill operation is continued, talc changes fine particle aggregation and crystal structure change due to mechanochemical effects, and the phenomenon of detachment of the (OH) group around Mg in the crystals becomes remarkable. The flowability of the ground product is inhibited by the withdrawal of (OH) from the talc crystal, but this flowability is restored when it is dried. When the power source unit in the grinding approaches 3 kWh/kg, it asymptotes to the maximum value of 9% in the weight reduction percentage.

Wet granules are used in various areas, owing to their higher compressibility. In this study, finite element method (FEM) simulations of wet granule compression are performed to discuss the influence of binder on the compressibility of wet granules. The Drucker-Prager Cap model was applied to wet granules with parameters obtained from compression and powder shear tests, and the FEM simulation was performed using these parameters. The results showed that the axial stress at the bottom surface and the radial stress of the wall obtained from the FEM simulation were consistent with the experimental values for the bottom and radial (wall) stress of the compression cell in large strain regions. Furthermore, the FEM results for wet granules with different amounts of binder suggested that particles in wet granules with higher amounts of binder adhered each other more strongly, thereby increasing the axial and radial stresses.