For large scale use of renewable energy, hydrogen society is necessary to overcome supply and demand mismatch in time and space. Polymer-electrolyte fuel cells (PEFCs) represent a superior system that exhibits high-efficiency, offering better power generation, meeting the desired levels of demand. However, in order to facilitate widespread use of fuel cells, cost and lifetime problems must be resolved. We are systematically designing and developing new materials from the molecular level to the device level. In the fuel cell systems, different components such as membrane, catalysts, and catalyst layer share significant functions and work in a well-coordinated manner, and hence, the total cell system must be optimized for the best performance. The systematic design and developing approaches concerning electrocatalysts for PEFCs are proposing.

A new simulation model to deal with metal powders was developed. The feature of the proposed model is to express plastic deformation behavior of metal powders. The model is based on Advanced Distinct Element Method (ADEM), which can represent deformation behaviors of elastic materials. The change of the proposed model from ADEM is interaction force of primary particles. In order to confirm the validity of the new model, compression tests and drop tests have been carried out in experiment and simulation. In compression tests, test tablets were thinly stretched and the deformation was maintained. In drop tests, a dimple was formed on the tablet when an iron ball collides. Characteristic behaviors of metal material such as stretching the tablets and forming a dimple were also confirmed in simulation. Therefore, it is identified that the proposed model could express the behavior of metal material.

A new model for estimating macroscopic permittivity was proposed to predict dispersion states of filler particles in a particulate composite material. In the model, the estimation targets are random packed composite materials. The composite materials were represented as a cluster of unit cells. The unit cells were connected by a proposed layer structure model. The macroscopic permittivity was estimated by calculating a synthetic capacity of the cluster.

The proposed model was validated by comparisons between estimated and measured macroscopic permittivity of several particulate composite materials. In addition, it was identified that the proposed model could estimate the permittivity more accuracy than an existing theoretical equation’s one due to considering the effects for the dispersion states of filler particles. Furthermore, it was indicated that the proposed model could also estimate the dispersion states of filler particles by the measured permittivity. The applicability of the method was confirmed by comparisons between estimated and experimental dispersion states of filler particles.

The uptake of nanoparticles (NPs) into biological cells with rigid cell walls is poorly understood. Interestingly, the authors demonstrated that positively charged polystyrene NPs were taken into yeast cells in the physiological saline. However, the polystyrene NPs are not suitable for carrier NPs due to their low biodegradability. In this study, we evaluated the uptake of biodegradable poly(lactic-co-glycolic) acids (PLGA) NPs into the yeast cells. As a result, PLGA NPs were taken into yeast cells regardless of their surface potentials. The yeast cells were alive after the uptake of negatively charged NPs, whereas the cell viability for the positively charged NPs was low. In addition, the experiments using endocytosis inhibitors suggested that the uptake of PLGA NPs was different from the conventional endocytosis. These experimental results strongly suggested that the negatively charged PLGA NPs are suitable for the delivery of useful substances to eukaryotic cells with cell walls.

Monolayer films composed of ordered particle arrays exhibit unique optical properties, which lead to various potential applications like sensors and antireflective coatings. In this study, we investigated particle deposition processes by using a drag coating technique based on convective self-assembly. Unlike micron-sized particles, 300-nm particles formed submonolayers instead of monolayers. Hence, we modified the technique and demonstrated that reversed dragging, introduction of a film blade, and periodic change in deposition speed dramatically improved the particle deposition process to cover the entire substrate surface uniformly with a monolayer of ordered particle arrays. Furthermore, our modified drag coating process produced monolayers of particles with different sizes of 570, 120, 45, and 27 nm. Thus, our technique is simple and versatile, and is applicable to a wide particle size ranging from microns to tens of nanometers.

Computational fluid dynamics has been increasingly adopted as a promising tool to understand the essential dynamics of particulate flow. The present review gives a brief description of numerical methods to describe the boundary condition of moving solid surface at lattice Boltzmann method (LBM), including bounce-back (BB) method (and improved BB method), immersed boundary (IB) method, and smoothed profile (SP) method. It is essential to choose an appropriate numerical method according to the target system. Among these methods, the author and coworkers have used the SP method to efficiently simulate flows including a number of particles. Here, typical results obtained by the SP-LBM simulations are presented.

Preparation of boehmite-silica composite particles using heterocoagulation was studied to improve the packing ratio and flowability of the particles used as fillers and flame retardants in resins. By measuring the zeta potential of each particle, silica showed a negative charge at pH > 2, and boehmite showed a positive charge at pH < 9. Therefore, mixing of each suspension of silica and boehmite prepared at pH 4 successfully produced boehmite-silica composite particles by heterocoagulation. We used two different silica particle sizes. Using smaller silica particles, composite particles uniformly coated with silica were obtained. The composite particles showed excellent fluidity in liquid paraffin, which suggested improved packing ratio.

Magnetorheological Fluids (MRF) whose apparent viscosity is controllable by applying magnetic fields are known as a kind of functional fluids. It is generally considered that such viscosity changes are caused by the formation of chain-like clusters of magnetic particles dispersed in the fluid. Many researches have been conducted to understand the mechanism of the viscosity change of MRF but there are few report which directly indicate the relation between the cluster formation and the viscosity change because of the difficulty of the observation such phenomena simultaneously. In this study, the relation between particle clustering and viscosity change has been investigated using DEM-DNS simulation. The simulations are conducted just a few chain-like clusters of magnetic particles in simple shear flow and the simulation results indicate that the apparent viscosity corresponds to both of the chain length and the angle between magnetic field direction and chain axis which depend on the Mason number.

Surface modification of functional polymers onto liposomes is effective strategy to obtain functional liposomes that release drugs at target site or intracellular compartments. Here, design of pH-sensitive liposomes for cell-specific intracellular drug delivery was summarized. Liposomes modified with hyaluronic acid derivatives exhibited selective anticancer drug delivery to CD44-expressing cancer cells. Furthermore, liposomes modified with curdlan derivatives were efficiently recognized by dendritic cells, leading to efficient antigen delivery, activation of dendritic cell and induction of antitumor immunity on tumor-bearing mice. Therefore, functional polymer-modified liposomes are promising for cell-selective cancer chemotherapeutic system or immunotherapeutic systems.

Thermally conductive polymer composites offer new possibilities for the thermal management in electronic devices. An approach of current interest to improve the thermal conductivity of polymer composites is the addition of high thermally conductive fillers with different shape and size. This paper described an overview of the microstructural design techniques for polymer composites with high thermal conductivity, and recent progress and advances that have been made on the enhancement of thermal conductivity of the polymer composites.

In an industrial incinerator, suppression of ash emission is of great importance from a viewpoint of environment preservation. In some of the incinerators, a control plate is equipped to suppress the ashes, where it is designed based on engineers’ experience. The control plate is assumed to recoil the ash particles. On the other hand, effect of the control plate has not been examined sufficiently, and besides behavior of ash particles has not been figured out in the incinerator. This is because the incinerator scale is so large that validation tests cannot be performed. In the present study, a numerical technology is applied to an industrial incinerator to examine the effect of the control plate and to analyze the ash particle behavior. In the numerical simulations modeling of an arbitrary shape wall boundary and large-scale simulation technique are required. In this study, advanced DEM-CFD method is employed, where coarse grain model of the DEM is used as scaling law modeling and signed distance function and immersed boundary method are applied to arbitrary shape wall boundary in the DEM-CFD method. The numerical simulations illustrate that the control plate works effectively, whereas, against all expectations, the ash particles are shown to remain in the incinerator not by collision to wall but by settling on the plate due to vortex.

The choking prevention effect on dense-phase pneumatic conveying has been investigated experimentally while moisture and particle diameter are changed. Consequently, the adhesion force between particles and pipe wall has been increased drastically with increasing of moisture content. However, it has been reduced with ultrasonic in spite of experimental condition. This means the possibility of choking can be removed with ultrasonic vibration. Additionally particle motion on the ultrasonic vibration plate was analyzed. This result showed that particle velocity increases along with particle diameter and moisture content influences on only large-sized particle. This cause was considered that heavy particle which includes a lot of water cannot jump in long distance and water makes the meniscus between particle and wall.

To understand the detail structure of the pulverized coal flame, it is necessary to apply the carefully controlled optical diagnostics because the significant signal disturbance from the fuel particles would reduce the accuracy of data. In this paper, the highlight results obtained by applying shadow Doppler particle analyzer (SDPA) and laser induced incandescence (LII) and time-resolved LII (TiRe-LII) to the pulverized coal flame were summarized.

This study aims to evaluate granules and tablets properties prepared by twin-screw continuous granulation (TSG) by comparing with those by fluidized-bed granulation (FBG) and high shear granulation (HSG). During FBG, mass median diameter increased in proportional to moisture content of wet granules. In HSG and TSG, granules growth was observed with an increase in mass ratio of liquid to solid. The mass median diameter was affected by the blade rotation speed at higher level of water content in HSG. By contrast, granule growth was less affected by the screw rotation speed in TSG. Friability and density of granules prepared by TSG remained between FBG and HSG. Scanning electron microscopy and cross-sectional 3D X-ray tomography images suggested that granules prepared by TSG did not receive high shear force as HSG during the granulation. The tablet strength and the percentage of dissolution were similar with those by FBG. It was because granules prepared by TSG had relatively porous structure as FBG. Under practical operation conditions, the tablet properties were comparable with those by FBG and HSG.

The method to improve the properties of dry granules was investigated by introducing pre-coating process with an active pharmaceutical ingredient (API) and a submicron-sized binder prior to conventional roller compaction. Hydroxypropylcellulose (HPC) and acetaminophen (APAP) were used as models of a binder and a low-compactible API, respectively. The submicron-sized HPC (HPC-subMP) was obtained by a lab-scale spray dryer. The APAP particles were pre-coated with 5–10% of the HPC-subMP by a high shear mixer, formed into granules using a lab-scale roller compactor, mixed with other excipients and then compressed to make them tablets containing 50% APAP. The tablets prepared with the HPC-subMP showed a high tensile strength without significant retardation of the disintegration time in comparison to those with a raw HPC particle, indicating that the use of API particles pre-coated with submicron-sized binder particles in roller compaction was effective to prepare granules suitable for tableting without any fundamental changes of materials and manufacturing processes.

Recently, ferroelectrics with relatively small bandgap energy have been receiving much attention because of the characteristic photoinduced electrical responses under visible light irradiation. However, such photoresponsive materials have serious problems such as poor photoelectric conversion properties, especially low photocurrent. It revealed that incorporation of silver (Ag) nanoparticles in the film as a surface plasmon excitation agent is effective to enhance photocurrent of narrow bandgap ferroelectric (such as BiFeO₃) thin films. The synthesized BiFeO₃ and Ag nanoparticle/BiFeO₃ thin films demonstrated rapid on/off responses of photocurrent to visible light. The Ag nanoparticle-embedded BiFeO₃ film exhibited a several times higher photocurrent than the BiFeO₃ film.

In this study, a novel reversible control method for particle dispersion/flocculation was developed. We found that the conformation of a polymer with solubility pressure dependencies on the side chain changed from random coil to fibril-like with ambient pressure. On the contrary, as we reported in our previous paper, the dispersion state of slurry changes with changes in the conformation of adsorbed polymers. Based on these results, we hypothesized that the dispersion state of the slurry can be reversibly controlled by ambient pressure. The sample used was aqueous slurry of alumina with a sodium salt of sulfonic acid copolymer with a relative molecular mass of 10000. The results showed that the dispersion state of slurry at atmospheric pressure was flocculated with a specific additive amount of polymer. On the contrary, after pressurization, the dispersion state was changed into a well dispersion state. Therefore, it was confirmed that the slurry was responsible for the pressure; thereby, a novel reversible control method for particle dispersion state was successfully developed.

The control of powder flowability with fine particles is important for tablets prepared by direct compaction. In the present study, the addition ratio of two types of fine particles of silicic acid compounds that can be used as glidants was examined to improve powder flowability. The powder sample, lactose, with a count median diameter (D_P50) of 103 μm, was used as an excipient, while magnesium aluminometasilicate (MA; D_P50 = 1.2 μm) and magnesium silicate (MS; D_P50 = 0.6 μm) were used as glidants. MA or MS was added to the excipient at different ratios in a range from 0.2 to 3.0 mass%. Powder flowability was evaluated by a vibrating tube method, which can characterize both the static and dynamic friction properties, and by conventional methods, i.e., measuring the angle of repose and compressibility. From a series of experiments, it was found that MA is more effective than MS in improving powder flowability, but with a strong dependence of addition ratio.

Xerogels were prepared from mixed aqueous ethanol solutions of Tetraethyl orthosilicate (TEOS) and hydrated iron nitrate, and their properties were investigated using XRD, TEM, FTIR, and VSM. As the heat treatment temperature of the iron oxide particles increased, the γ-Fe₂O₃ and the ε-Fe₂O₃ were precipitated, and the particle diameters increased.

For heat treatment at 1100°C, the α-Fe₂O₃ was observed when the Si/Fe ratio was 1.5, while the ε-Fe₂O₃ was formed when the Si/Fe ratio was 2.8, 5.7, and 11.4. The particle diameter of the ε phase increased with decreasing Si/Fe ratio. By adding yttrium, crystal growth of the iron oxide particles was promoted, and the particle diameters and the coercivity consequently became larger than that of the sample without yttrium present.

Preparation of Mg particles were carried out by using a pulsed wire discharge method, which is a physical vapor method in organic matter fume/vapor and is beneficial for passivated metal nanosized powders. From results of powder X-ray diffraction, the sample consisted of single-phase Mg. Electron diffraction and transmission electron microscopy observations revealed that Mg submicron particles were seen even though the presence of fine MgO particles. After an oxidation test at room temperature in air for one month, the oxidation did not progress. From these results, it was concluded that alkaline earth metal particles can be mass-produced by the pulsed wire discharge.