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.

Continuous wet granulation using a twin-screw granulator has attracted much interest in the pharmaceutical industry. The physical properties of granules prepared through the twin-screw granulation process depend on the several factors, such as screw and barrel geometries, operating conditions, and formulations of raw materials. In particular, it is known that the fill level in a twin-screw granulator and the binder additive ratio have an impact on the twin-screw granulation process. In this study, mutual effects of the two major factors on the granulation process was investigated experimentally and numerically. By combining the experimental and numerical analyses, a prediction model of the granule growth rate was proposed. The proposed model demonstrated that the granule growth rate was determined by the total energies (compressive and shear directions) and the index of granulation.

In this study, we focused on the low-temperature preparation of the typical Garnet-type cubic solid electrolyte powders of lithium lanthanum zirconate (LLZO) with new dopants. We chose the new dopants of Mg and Sr to stabilize the cubic phase by different preparation methods. One is the solid state reaction with a wet chemical coating of Li source, and the other is the all wet chemical processing of so called modified sol-gel method. As a result, we successfully prepared cubic LLZO powders with Mg and Sr dopants by the modified sol-gel method at lower temperature. In addition, new dopants affected the stability of the cubic phase if compared with the other dopants such as Al and Ta. The modified sol-gel method was the powerful tool to stabilize the cubic phase because of the high homogeneity of a precursor at the molecular level by the suitable molecular-design of the precursor solution.

Suspensions of monodisperse spherical particles under shear flow were simulated using a solid-liquid two-phase model based on coupled lattice Boltzmann method (LBM) and discrete element method (DEM). Evaluating the shear stresses due to the viscous behavior of the bulk fluid, the hydrodynamic interaction between particles and fluid, and the physical contact between particles, the contribution of each factor to the suspension viscosity was investigated. The results showed that in the range of low to moderate particle volume fractions, the viscosity of suspensions is mainly determined by the action of the fluid, and that the contribution of particle contact increases with increasing particle volume fraction. In particular, the flow behavior of dense suspensions should be viewed not as a fluid motion but as the motion of a group of particles. From these results, in order to predict and control the rheological properties of particle suspensions, it is important to understand that the main factors increasing viscosity vary with the concentration range of interest.

In this study, we investigated milling characteristics of sulfide solid electrolytes (SEs) for all-sold-state lithium ion batteries (ASSLIBs). Subsequently, we employed the milled SEs as guest particles for dry coating of cathode active material (AM), and examined the influence of SE size distribution on ASSLIB performance. Our finding revealed that SE particles have unique milling characteristics, in which coalescence of milled fine particles occurs simultaneously with size reduction by milling. The dry coating experiments confirmed that the use of milled SEs (guest particles) resulted in more uniform coating of the AM (host particles) with SE, leading to significant improvement in the performance of ASSLIB (630% increase in capacity as compared to unmilled SEs). However, when SEs were excessively milled, the SE coating layer exhibited non-uniform morphology, resulting in lower battery performance (15% decrease in capacity). Consequently, our results highlighted that there is an optimal milling condition for SE guest particle for the dry coating.

The Sustainable Development Goals were adopted by the United Nations in 2015. Technologies that realize an economically low-carbon society are attracting attention of the international community. Regarding powder processing technology and device development, we will introduce examples of technological development that contribute to the achievement of the SDGs (Sustainable Development Goals).

The photoluminescence (PL) intensities of Li-Ta-Ti-O:Mn⁴⁺ red phosphors were successfully improved under various oxygen partial pressures in an air-pressure control atmosphere furnace (APF). The Mn phosphors were synthesized using an APF and a conventional electric furnace (EF) with the composition formula Li_1.33Ta_0.67Ti_0.33O₃ as the host material. The effects of oxygen partial pressure on the Mn⁴⁺ ratio and crystal structure for the PL intensity were investigated. As a result, the PL intensity was enhanced under high oxygen partial pressure, showing about 2.6 times higher than the phosphor synthesized by EF.

Alginate capsules for encapsulating probiotics were synthesized under mild conditions without using harmful chemicals. When alginate capsules were synthesized using glucono-δ-lactone while suppressing the rapid pH drop of the inner water phase, it was possible to encapsulate living lactic acid bacteria. It was also found that coating the alginate capsule surface with chitosan improved the protective effect of the encapsulated lactic acid bacteria. Furthermore, culturing the encapsulated bacteria inside the capsules increased the number of living bacteria to meet the minimum recommended level for probiotic effect. Finally, we demonstrated that almost all encapsulated bacteria were released within 60 minutes in simulated intestinal fluid. From the above, it was suggested that the chitosan-coated alginate capsules synthesized in this study can be used as capsules for encapsulating probiotics.

SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is a single-stranded RNA virus which causes COVID-19 (coronavirus disease 2019). SARS-CoV-2 invade a human airway epithelium cell through binding of its Spike (S)-protein to ACE2 (angiotensin converting enzyme 2). Approved anti-inflammatory drugs and a viral RNA-dependent RNA polymerase (RdRp) inhibitor underdevelopment for other disease were repositioned for the COVID-19 treatment. Furthermore, neutralization antibodies targeting the S-protein and antiviral drugs of RdRp or 3CL protease inhibitors were newly developed within only 3 years. The innovations of the drug discovery and development, including regulation, realized the rapid release of drugs to the market.

Comminution process is widely used in industry to produce fine particles. We developed a mathematical model of comminution in order to analyze particle size reduction in an impact pulverizer. In our model, it is assumed that parameter a, which represents particle breakage modes, depends on both impact velocity and size of the particles. To obtain that dependence, particle-size distribution was measured experimentally before and after the breakage using a jet-mill. We implemented the mathematical model into the simulation based on computational fluid dynamics (CFD) and discrete phase model (DPM). It was confirmed that the simulation results coincide with the experimental ones in a rotary mill. Therefore, we conclude that it is important to consider the dependence of impact velocity as well as particle size on the breakage modes.