This paper describes separation performance of newly developed forward cyclones with 7 kinds of size and structure. The forward cyclones have 2 or 4 tangential-air-inlets, a dust pot and a flow receiver for fine particles. Our previous study showed that the cyclones had sharp size separation performance for PM_2.5 but did not clarify the mechanism. Size separation characteristics of the cyclones were evaluated using a pair of optical particle counters with test aerosols of standard polystyrene latex particles ranging from 1 to 6 μm in diameter. Also swirling flow in the cyclone was observed by tracer powder. Measured data, such as 50% cut-off aerodynamic diameter at flow conditions of each cyclone, were used to estimate the flowrate branching off the dust pot. Ranging from 3 to 30 percent of total flowrate were passed to the dust pot before flow throughout the cyclone. The flow caused sharp centrifugal separation to the aerosol particles introduced into the cyclone. Smallest the cyclone (bore diameter was 10 mm) covered samplings for PM_2.5 fraction of ambient aerosols at 3 L/min and respirable particle faction (PM₄) at work environments at 1.7 L/‍min. Largest the cyclone (bore diameter was 90 mm) fitted to a high-volume air sampler of which flowrate ranged from 150 to 600 L/min, showed the same performance as the smallest one.

The sustained-release formulations consist of many components, such as the active pharmaceutical ingredient, excipient, binder, lubricant, and polymer, leading to the complex dissolution process. The objective of this study is the elucidation of the rate-determining step in the dissolution process by direct optical observation. The composite particles of hydroxypropyl methylcellulose (HPMC) and brilliant blue FCF (model drug) were prepared, and the direct observation of the dissolution process and image analysis were conducted. The decrease in particle size and the penetration of solvent into the particles during the dissolution process had little impact on the sustained-release performance. On the other hand, the diffusion rate of the model drug in the HPMC gel strongly depended on the type of HPMC, suggesting that the rate-determining step in the dissolution process of the sustained-release formulations using HPMC would be the drug diffusion process in the polymer gel in the particles.

In the field of non-equilibrium science, the Liesegang phenomenon is well-known as a particle formation process involving the diffusion of precursor chemicals. From a chemical engineering perspective, our research group had previously applied this method to synthesize metal nanoparticles and found that when Au ions diffuse unidirectionally into a gel containing a reductant, bands of Au nanoparticles are formed in a striped pattern. However, metal species other than Au have not yet been investigated. In this study, we synthesized nanoparticles of other metal species (Pt and Pd) using a similar process and compared the results with those of the Au nanoparticles to clarify the particle formation mechanism. The findings showed that the band patterns that were formed vary according to the metal species. Furthermore, the bands formed in each metal species were reproduced by using a mathematical model capable of representing the diffusion of ions and the formation of particles.

Currently, slurry coating is used in the manufacturing process of various products such as electrode films for batteries, electronic materials, and optical materials. However, it is well known that the distribution of material composition in the electrode film has a significant impact on the performance of the device. A slurry is a mixture of powders, binders, and additives dispersed in a liquid, and when this mixture is coated and deposited, the mixed materials are randomly distributed. Furthermore, in the process of drying and removing the dispersant, the binder moves with the dispersant and segregates, while the particulate additives tend to aggregate. Segregation of the binder and agglomeration of the conductive agents may result in poor battery characteristics. To solve these problems, we thought it would be effective to make the base material and the additive material bonded together to form composite particles.

NCM-PEI-GO composite particles were synthesized by forming an ionic complex consisting of polyethyleneimine (PEI) and graphene oxide (GO) on the surface of lithium transition metal oxide (NCM), a cathode active material. In this study, composite particles were synthesized by adding different amounts of PEI and GO, and the effect of the amount of PEI added on the size and thickness of the ionic complexes and the aggregation state of the composite particles was investigated, and the effect of the amount of GO added on the conductivity was discussed. The amount of GO added had no effect on the thickness of the ionic complexes, but had a significant effect on the aggregation of the composite particles.

The conductivity of the NCM-PEI-GO composite particles increased with increasing GO content. This may be due not only to the increase of conductive graphene species in the electrode film, but also to the enhanced conductive path due to the linkage and aggregation of composite particles by ionic complexes.

It is desired for the pharmaceutical intermediate products to form as powder, considering versatility of storage, transportation, and the production schedule adjustment. In this study, aqueous suspension composed of nano- and submicron sized poorly water-soluble drug particles ground by a wet milling was spray dried to produce dry particles. Crystallinity of indomethacin particles was maintained after the spray drying. It was found that mannitol prevented indomethacin particles from cohesion during the spray drying; when indomethacin particles and mannitol in the four times amount of indomethacin were spray dried, mannitol absolutely prevented indomethacin particles from cohesion during the spray drying and the dissolution profiles of the spray dried powder were maintained at the same value as the suspension of indomethacin particles.