In this study, we developed amorphous drug nanoparticle-forming solid dispersion (ASD) formulations and quantitatively evaluated the effect of amorphous drug nanoparticle formation on drug intestinal absorption. Fenofibrate (FFB)/hypromellose (HPMC) ASD was prepared by spray drying of FFB as a model poorly water-soluble drug and HPMC as a polymer carrier. In the FFB/HPMC physical mixture (PM) suspension, μm-order FFB crystals were dispersed, while amorphous nanoparticles of about 160 nm were formed in the FFB/HPMC ASD suspension. The dissolved FFB concentration in the FFB/HPMC ASD suspension was about 8.6 times higher than in the FFB/HPMC PM suspension. The evaluation of nanoparticle uptake into rat small intestinal epithelial cells suggested that nano-sized amorphous FFB particles were taken up directly into the small intestine. FFB intestinal absorption from FFB/HPMC ASD suspension was improved about 37-fold compared to FFB/HPMC PM suspension, and the improvement in FFB absorption was greater than the improvement in FFB solubility, leading to the conclusion that direct uptake of amorphous FFB nanoparticles in small intestinal epithelial cells contributed to significant improvement in FFB absorption.

This study investigated the effect of the particle properties on the flowability and the cohesiveness of the powders using a test of the powder discharge by air pressure. The particle used was the silica particles of 5 μm and 16 μm, and the quartz sand of 8 μm. Cohesiveness was evaluated by the Bond number (Dimensionless quantity that expresses the ratio of separation force and gravity). Flowability was confirmed by the mass flow rate of the powder and the air pressure during the powder discharge. The obtained results were compared with the measuring results of the powder tester and the powder rheometer. As a result, the cohesion of small silica particles was high, and the flowability tended to be poor. In addition, it was found that the cohesion of quartz sand with low circularity increased, and the flowability also became poor. These results clarified that particle physical properties, such as particle size and circularity, affect the cohesion and flowability of powders. Furthermore, the results of the powder discharge test by the air pressure and the existing evaluation test obtained similar tendencies. From this, it is considered that the powder discharge method using the air pressure can be applied as one of the powder cohesion and flowability evaluation methods.

Our research group has successfully synthesized polyacrylic acid modified titanium dioxide nanoparticles (PAA-TiOx NPs), which are titanium dioxide nanoparticles (TiO₂ NPs) peroxidized with H₂O₂ and modified with PAA. PAA-TiOx NPs retain H₂O₂, which increases the radiosensitivity of tumors, inside the particles and release H₂O₂ slowly into the dispersion. In vivo, a certain number of PAA-TiOx NPs accumulated in the tumor. However, accumulation normal organs was also observed. In order to improve the retention of TiOx NPs in cancer tumors, α-Glucosylrutin (RutinG) was investigated as a new modifier to target GLUT1, which is overexpressed on cancer cells in this study. RutinG-TiOx NPs were prepared by following procedures: (1) Coating TiO₂ NPs with RutinG, and (2) Adding hydrogen peroxide. RutinG + PAA-TiOx NPs were also prepared by adding RutinG to PAA-TiOx NPs. Next, to verify the radiosensitizing effect of RutinG-TiOx compared to PAA-TiOx NPs, the amount of H₂O₂ adsorption and desorption was quantified by the chemofluorescence method. These results suggest that GLUT1 is involved in the subcellular localization of RutinG-TiOx. RutinG-TiOx NPs assumed to be used as a radiosensitizer by active targeting in cancer therapy with X-ray irradiation.

Tiny droplets have high specific surface area and hence they experience unique chemical reactions, which do not occur in bulk phase solutions. Especially, the enhancement of chemical reactions in small droplets is of great importance and is associated with incomplete solvation of reactants at the air-liquid interface. Nonetheless, the fundamental understanding of the origin of the reaction enhancement remains to be understood. Here, this research project aims to develop single particle analysis to advance our understanding of physicochemical properties of small droplets. This report will mainly present the results of quasi-elastic scattering method.

Hemolysis assay using red blood cells has been widely used as the simplest cytotoxicity test for nanoparticles. Nevertheless, the hemolytic action mechanism of nanoparticles is still poorly understood. In this study, the hemolytic action of silica nanoparticles with different particle diameters (5–120 nm) and surface functional groups (none, amino group, and carboxyl group) was investigated under different exposure environments: temperatures (4–43°C) and phosphatic buffered saline solutions (additive-free, serum added, and serum albumin added). Adding to the hemolysis assay, the adhesion number of nanoparticles to red blood cells and the aggregation/dispersibility of red blood cells were measured, whereby the overall picture of the hemolytic action mechanism of nanoparticles was given.

In order to functionalize the powders, it is important to understand the relationship between the powders’ structure and their functionalities. As one of the techniques, the Mahalanobis-Taguchi system (MTS) has been utilized because that effective variables which improve accuracy of classification can be visualized. The surface-roughness-related variables were the effective powder structure which improve accuracy of classification into male/female of Japanese beetles larval droppings as the model powders. Considering that binder concentration in the females’ dropping was higher than in the males’ dropping, the females’ droppings could be deformed during molding process through the larval gut. The MTS can be expected as the effective way to improve the accuracy of the classification by visualization of the relationship between powder structure and functionalities without individual differences.

The particle aggregate structure formed during drying is desired strongly to control elaborately and flexibly in products and manufacturing processes using particle suspensions, because it is critical to the final performances. However, a direct understanding of the phenomenon under the actual environment is difficult due to the complexity of various factors that affect each other. To solve this issue, an operando observation system that can simultaneously measure the drying characteristics curves, which is the standard-scale of materials, and observe the internal structural changes was constructed in this study. The system consists of a swept-source optical coherence tomography (SS-OCT) for observation, an electronic balance for measuring weight change, and a probe for measuring environmental temperature and humidity change. The drying behavior of coffee droplets and Al₂O₃ slurry was observed using this system, and it was found that the internal structural changes during drying could be directly correlated with the drying characteristics and evaluated quantitatively. Furthermore, the influences of solid concentration and particle dispersion/agglomeration in Al₂O₃ slurry on the internal structure change and drying characteristics were also clarified.

We have developed a phase retrieval holography module for microparticle measurement. The system that this module has comprises two cameras connected to a single-board computer (SBC) with a graphics processing unit (GPU), a diode-pumped solid-state green laser, and a beam splitter. Furthermore, the GPU provides real-time reconstruction. The system can record the shapes and positions of particles falling in a static flow in a three-dimensional volume as two holograms generating an interference pattern. Phase retrieval holography with two holograms solves the twin image problem that arises due to the lack of phase information. We also present the requirement of this module for experimentally recording and numerically reconstructing holograms of particles. Finally, we conclude that holographic measurement, limited to use in a laboratory, can be used for in-line/ on-line measurement of powder production processes.

Ag particles supported on a metal oxide support have been used for various catalytic reactions (e.g. selective oxidation of ethylene). To improve the catalytic activity, size reduction of Ag particles is desired. However, it is challenging to obtain small Ag particles due to the low Tammann temperature of Ag. In this study, we successfully deposited 20 wt% of Ag clusters (~2 nm) onto TiO₂ using flame spray pyrolysis. The Ag clusters were stabilized by strong metal-support interaction (SMSI) between Ag and TiO₂ which was induced in the combustion reaction zone. SMSI formed TiOx as confirmed by X-ray diffraction. The amount of TiOx depended on the flame conditions and Ag content (10–40 wt%). The surface area of Ag clusters was estimated by H₂ pulse titration. The Ag surface area increased with Ag content up to 20 wt%, and by further increasing the Ag content to 40 wt%, the surface area did not change. The stability of Ag clusters depended on the Ag content, the flame conditions, and the specific surface area of the titanium oxide support. In the future, we will explore catalytic activity of FSP-made Ag clusters for some reactions.

A new crystallization process for producing nano-order ultrafine crystals was developed by combining anti-solvent crystallization with electrospray which can generate nanomist acting as a crystallization field. Anti-solvent crystallization was performed in a batch crystallizer using glycine as a crystallized material and alcohol as an anti-solvent. The effects of the operating conditions on the mean diameter of produced glycine crystals were investigated. The experimental results clearly demonstrated that the crystal diameter tended to decrease with increasing applied voltage and decreasing flow rate. A minimum mean crystal size of 192 nm was attained in a batch crystallizer. Next, a unique counter collision crystallizer was introduced and the effects of the operating conditions on the mean crystal diameter were investigated. As a result, the higher voltage and the lower flow rate produced smaller crystals similar to the batch crystallizer. The counter collision crystallizer could successfully produce crystals with a minimum mean diameter of 295 nm.

A microlens array is the optical element which has many lenses with a diameter of several to hundreds micrometers on the substrate surface. In the present study, we have tried to prepare the meso-lens array with a diameter of hundreds nanometers from the non-close-packed (NCP) colloidal monolayers, which are prepared by the convective self-assembly (CSA) using a quartz glass substrate and the silica particles grafted with cationic polyelectrolyte, poly(vinylbenzyl trimethylammonium chloride) (PVBTA). The PVBTA-grafted silica particles and the glass substrate were applied to the CSA process to prepare the NCP monolayers, and then the obtained monolayers were annealed in a muffle furnace for several hours. The annealed particle monolayers were observed by a scanning electron microscope (SEM) and an atomic force microscope (AFM). As a result, we found that the height of the silica particles decreases with an increase in annealing time, and the partially fused silica particles integrate with the quartz glass substrate to form a meso-lens array.

Si-Si σ bonds exhibit reactivity and physical properties similar to those of C=C π bonds. The research group is utilizing the flexibility of the Si–Si σ bond and the σ–π conjugation with aromatic substituents to investigate the synthesis, structure, and physical properties of various disilane-bridged macrocycles. We have already studied the synthesis and temperature-dependent behavior of a dimer (tetrasilacyclophane). Here we report on the synthesis of trimeric and tetrameric macrocycles and their crystal structures at different temperatures.

Owing to the growing demand for high power optical devices, the durable transparent materials with fluorescence are demanded. In this study, we focused on α-SiAlON ceramics, which have been developed as structural materials by taking advantage of their high thermal and mechanical properties, and realized blue light-emitting transparent Lu-α-SiAlON:Ce³⁺ ceramics. A higher Ce concentration resulted in a red shift of the fluorescence. Furthermore, using finer raw powders of rare-earth oxide improved the in-line transmittance of Lu-α-SiAlON:Ce³⁺ ceramics.

To control particle size and crystal polymorph, it is essential to understand the nucleation process, which is the initial step of the solid phase deposition in particle syntheses. Recent studies show that the nucleation pathway significantly varies from a one-step pathway to a two-step one via a liquid cluster depending on the types of molecules as well as operating conditions. To clarify the physical factors that determine the nucleation pathway, we performed molecular dynamics simulations in a binary Lennard-Jones system and developed a thermodynamic model to predict the pathways based on the molecular properties.

The discrete element method (DEM) is widely used to analyze powder mixing processes, however DEM simulation is limited by the computing capability. Hence, we proposed an original model, namely Recurrent Neural Network with Stochastically calculated Random motion (RNNSR), to simulate the powder mixing with low computational cost. RNNSR combines recurrent neural network and stochastic model, adapting to powder mixing simulation in rotating drum mixer. The performance of RNNSR was evaluated in terms of degree of powder mixing and effective computation speed. As a result, RNNSR was able to simulate the powder mixing with ultra-fast speed.

FAU-type zeolites, which are one of large-pore zeolites with 12-membered rings, are widely used industrially as catalysts, adsorbents and separation membranes for various molecules. In general, conventional FAUs are synthesized under hydrothermal synthesis conditions of around 100°C and several days’ heating. In this study, high-silica FAU was succeeded in synthesis under the condition of higher temperature (180°C) and short heating time (3 h) by combining highly reactive dealuminated amorphous matters, prepared by acid-treatment, with a seed-directed approach. In addition, it was found that the obtained FAU-type zeolites have unique Al distribution compared with previous FAUs.

Particle Size Distribution (PSD) analysis for nanoparticle is important for productivity improvement in Chemical Mechanical Polishing (CMP) process. CMP slurry, which consists of nanoparticles in suspension, contains multi-modal PSD due to particle aggregation. In this study, we suggested a novel particle sizing method using nanoparticle chip (NPC). NPC can maintain the aggregation condition of particles to transfer the particles from suspension to the substrate. In this report, a fundamental experiment was performed to investigate the evaluation method of equivalent height diameter using NPC.

Fertilizers, which are essential for food production, are absorbed by plants in less than half of the amount applied to the soil. As an efficient method of absorbing fertilizer, there is a method of absorbing fertilizer from the leaves of plants (i.e. foliar route). However, the method of transportation in the form of an aqueous solution in which the fertilizer is dissolved is not applicable to macronutrients. In the present study, the goal is to control the dissolution of particles on leaves during the particle transport in the solid state. The effect of properties such as crystal structure of the synthesized multicomponent particles on the dissolution properties was investigated.

In this study, molecular dynamics simulations of NaCl crystal growth were performed to analyze the adsorption mechanism of solute ions onto the NaCl surface during the initial growth stage. Both Br^– and I^– were found to decrease the adsorption rate, but the impurity effects of these ions were different. In the presence of Br^–, the adsorption rate was decreased by the limiting effect of the adsorption rate of Br^–. By contrast, in the presence of I^–, the adsorption rate was reduced by the abundance of I^– near the interface as the supply of Cl^– near the interface was limited by electrostatic effects.

The purpose of this study was to improve the solubility of three poorly water-soluble polyphenols by amorphous formation with naringin (NAR). All spray-dried particles showed a halo pattern in powder X-ray diffraction measurements and showed a single glass transition temperature in differential scanning calorimetry. The spray-dried particles of poorly-water soluble polyphenols and NAR improved the solubility of hydrophobic polyphenols, especially the solubility of naringenin, which has a similar structure to NAR, was significantly increased.

The effects of polydispersity on the physical properties of granular matters are poorly understood. In this study, we investigate the binary mixtures of jammed particles with large size dispersity. Especially, we aim to clarify the nature of the elementary excitations in the binary mixtures. We found that structural properties exhibit apparent correlation near a critical point in the binary mixtures. We also found that the binary mixtures have more low frequency modes than the monodisperse granular matters.

Experiment was conducted on water vapor and aluminum powder combustion aiming to a micropropulsion system for small satellites. The water vapor pressure was approximately 80 kPa, and aluminum powder was spherical and –250 mesh size. The experiments clarified ignition delay, maximum pressure, pressure increasing rate, and combustion efficiency of the combustion. As a result, the propulsive performance of a micropropulsion system using water vapor and aluminum powder combustion was roughly estimated, and its future potential was confirmed.

Photocatalytic CO₂ conversion is a promising and clean way to convert the CO₂ to CO and useful components. TiO₂ is the most investigated photocatalysts for CO₂ conversion but it suffers from large bandgap around 3.1 eV. Using the rutile and anatase titanium oxide phases is prevalent for photocatalytic CO₂ conversion. Despite several attempts on photocatalytic CO₂ conversion of these two phases, the columbite TiO₂ (TiO₂-II) phase as a high-pressure TiO₂ polymorph had not been investigated for this application. In current work, we employed high-pressure torsion (HPT) to produce the defective TiO₂-II high-pressure phase and examined it for photocatalytic CO₂ conversion for the first time. Introducing the TiO₂-II phase significantly decreased the bandgap and improved the photocurrent density and photocatalytic activity of TiO₂ for CO₂ conversion.

Using the clean fuels such as H₂ is a promising alternative to be used instead of fossil fuels due to global warming issue. In this regard, photocatalytic H₂ evolution is the cleanest way to produce this useful component. There have been various attempts to introduce the photocatalysts for this application and among them metal oxynitrides have attracted attention due to their low bandgap. High-entropy ceramics are also new and promising materials due to their superior properties specially in catalysis. In this study, the concept of combination of metal oxynitrides and high-entropy ceramics led to design and produce a new high-entropy oxynitride (HEON) for photocatalytic H₂ evolution for the first time. This HEON successfully produces the H₂ because of its high light absorbance much better than relevant binary and high-entropy oxides and low bandgap around 1.6 eV. The H₂ production amount of this material was higher than Ga₆ZnON₆ as a convectional oxynitride for this application.

Porous pectin particles were developed as a protein adsorbent using a template-assisted spray drying method with calcium carbonate (CaCO₃) as a template for pore formation. The specific surface area was controlled from 177.0 m²/g to 222.3 m²/g by adjusting the CaCO₃ concentration. All porous pectin particles showed rapid adsorption (~65% within 5 min) and high adsorption capacity, increasing from 1543 mg/g to 2621 mg/g. The high percentage of available binding sites located in the macropores resulted in a high performance of this material, making it a promising advanced adsorbent for various macromolecules in the food and pharmaceutical industries. The porous pectin particles are derived from a natural polymer, contributing to sustainable development.

Water scarcity can make plants experience drought stress. This can happen from the germination stage. The seed priming method with silica nanoparticles was used to overcome this issue. Tomato seeds were soaked in a suspension of silica particles (average size of 10 nm). Drought stress was simulated by using polyethylene glycol (20,000) with concentration of 10–20 wt% in germination media. The results showed that the method of priming with silica nanoparticles was able to withstand drought stress and improve seed germination performance.