Hosokawa Powder Technology Foundation ANNUAL REPORT
Online ISSN : 2189-4663
ISSN-L : 2189-4663
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  • Toru ISHIGAMI
    2019 Volume 27 Pages 19-24
    Published: May 25, 2020
    Released: May 25, 2020
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    In this study, to clarify the mechanism of the permeation and collection through a filter, a direct numerical simulation model for multi-phase flows was newly developed. We extend this model to apply air filter and coalescer. To represent a realistic microporous structure inside the filters during simulation, a numerical method that coordinates the filter structure obtained by X-ray CT imaging with computational fluid dynamics is developed. The predictions of filter pressure drop from our numerical method were quantitatively in good agreement with the experimental measurements and the empirical equations previously reported. Finally, we demonstrated that the present method can be easily extended to multiphase flow simulations.

    Graphical Abstract Fullsize Image
    Pressure contour for PPS filter of ε = 0.853.
    Editor’s picks

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  • Tomoya OHNO
    2019 Volume 27 Pages 25-30
    Published: May 25, 2020
    Released: May 25, 2020
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    Microstructure of the air-electrode for metal air battery was controlled by dispersion control between catalyst and carbon particles in the ink. The dispersion of each particles was controlled by the electrostatic repulsion force in the ink. The surface area of catalyst particles in the air-electrode was improved by the hetero coagulation between catalyst and carbon particles in the case of nano-particle catalyst. On the other hand, the relatively large surface area of catalyst in the air-electrode was attained at the well dispersed condition in the case of the catalyst particle with sub-micron diameter. As a result, the catalytic activity for oxygen evolution reaction increased with increasing the surface area of catalyst in the air-electrode.

    Graphical Abstract Fullsize Image
    OER activity of the obtained air-electrode (catalyst: CSRO) using the ink with different pH.
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  • Satoshi OHARA
    2019 Volume 27 Pages 31-34
    Published: May 25, 2020
    Released: May 25, 2020
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    A core–shell anode consisting of nickel–gadolinium-doped-ceria (Ni–GDC) nanocubes was directly fabricated by a chemical process in a solution containing a nickel source and GDC nanocubes covered with highly reactive {001} facets. The cermet anode effectively generated a Ni metal framework even at 500°C with the growth of the Ni spheres. Anode fabrication at such a low temperature without any sintering could insert a finely nanostructured layer close to the interface between the electrolyte and the anode. The maximum power density of the attractive anode was 97 mW·cm–2, which is higher than that of a conventional NiO–GDC anode prepared by an aerosol process at 55 mW·cm–2 and 600°C, followed by sintering at 1300°C. Furthermore, the macro- and microstructure of the Ni–GDC-nanocube anode were preserved before and after the power-generation test at 700°C. Especially, the reactive {001} facets were stabled even after generation test, which served to reduce the activation energy for fuel oxidation successfully.

    Graphical Abstract Fullsize Image
    HRTEM image of CeO2 (left) and Gd-doped CeO2 (GDC: right) nanocubes.
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  • Takashi OGI
    2019 Volume 27 Pages 35-41
    Published: May 25, 2020
    Released: May 25, 2020
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    This research demonstrated a simple, facile means for the production of monodisperse fine metal particles with high levels of crystallinity and purity using a rapid spray heating process. Fine particles of colloidal Ag (geometric mean diameter dp = 1.01 μm, geometric standard deviation σg = 1.22 and crystal size dc = 22 nm) prepared by a liquid phase method were used as a test material to evaluate the proposed technique, and the effects of drying temperature (200–900°C) on particle characteristics were investigated in detail. The particles obtained after spray heating at 500°C exhibited high crystallinity (dc = 40 nm) and high purity while keeping their initial morphology and size distribution (dp = 0.92 μm, σg = 1.24). The volume resistivity of the fine Ag particles after spray heating was 3.6 × 10–5 Ω·cm, which was considerably lower than that of fine Ag particles before spray heating (6.4 × 10–3 Ω·cm) by a factor of 180. The simple method proposed in this paper has the potential to produce high-quality fine particles of various metals suitable for real-world applications.

    Graphical Abstract Fullsize Image
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  • Mitsumasa KIMATA
    2019 Volume 27 Pages 42-47
    Published: May 25, 2020
    Released: May 25, 2020
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    The mechanochemical polymerization method uses active center of the powder fracture surface to produce by grinding operation, and it is method to approximately completely carry out a polymer coating in crushed inorganic surface. We focused the attention on the waste glass of the car which had low recycling percentage achievement, and we thought about reusing this as silica filler by mechanochemical polymerization processing now. We found what a polymer generated in the water recently by carrying out mechanochemical polymerization reaction with the high ability mill for grinding such as the planetary mill. Therefore, a preparation of the polymer coating silica filler by the wet grinding using the water was investigated. As a result, we succeeded in a preparation of the silica filler that surface of the waste glass was coated with a polymer. Hence progress of the mechanochemical polymerization reaction was confirmed by grinding of the waste glass in the water. In addition, the particle diameter of the product was around 200 nm without depending on the particle diameter of raw materials.

    Graphical Abstract Fullsize Image
    SEM and STEM images of the products. (a) 1180-600 μm (5 h), (b) Under 75 μm (9 h) (Grinding time)
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  • Tetsuo SAKKA
    2019 Volume 27 Pages 48-52
    Published: May 25, 2020
    Released: May 25, 2020
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    Emulsions stabilized by adsorbing fine particles are called Pickering emulsions, and are attracting attention as a technique for stabilizing emulsions without using a surfactant. The stabilization of the oil-water interface by the fine particles should follow a change in the interfacial tension, but it is not systematically understood. The purpose of this study is to clarify the effect of particle adsorption on the interfacial tension at the oil-water interface. Monodisperse and spherical particles were used to make it easier to analyze the effects of the particles. In the measurement of the interfacial tension, a quasi-elastic light scattering method was employed to avoid the effect of the probe contacting the interface. The interfacial tension at the decane/water interface was measured as a function of the number of adsorbed particles; the interfacial tension decreased with the amount of dispersed particles. The decrease in interfacial tension was much larger than the stabilization free energy due to the adsorption of the particles, or the repulsive interaction between the adsorbed particles, suggesting that the decrease is due to synergetic effects of structural change of the interface.

    Graphical Abstract Fullsize Image
    Experimental setup of quasi-elastic light scattering measurement based on optical heterodyne spectroscopy. The light scattered at the oil-water interface with a certain scattering angle is detected together with a portion of original light (local light) to give frequency shift by the scattering with capillary wave.
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  • Hiroyuki SHINTO
    2019 Volume 27 Pages 53-57
    Published: May 25, 2020
    Released: May 25, 2020
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    Using red blood cells (RBCs), we have fabricated functional soft particles, which exhibit not only several kinds of shapes but also biologically functional sugar chains of ABO blood group on the RBC membrane even after chemical fixation. It was found that chemical fixation of RBCs with paraformaldehyde significantly reduces the adsorption amount of bovine serum albumin on an RBC, but hardly affects that of lectins (i.e., proteins that recognize blood type sugar chains).

    Graphical Abstract Fullsize Image
    Scanning electron micrograph (SEM) images of chemically fixed rabbit-RBC with three different shapes: biconcave discocyte, spiculated echinocyte, and sphere, from left to right.
    Editor’s picks

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  • Chika TAKAI
    2019 Volume 27 Pages 58-62
    Published: May 25, 2020
    Released: May 25, 2020
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    The surface of the particles was identified using the Hansen solubility parameter (HSP). From a comparison of the HSP of the unmodified and modified silica, an NH2 group is suitable for entrapment of the silica by cellulose acetate as the polymer. However, with an increase in number of the silica particles, entrapment of the silica in the polymer was prevented. Control of the phase separation rate by the lowering temperature leaded to entrapment of silica particles in the polymer network. The proposed technique is effective not only for spherical oxide particles, but also for non-oxides, various shapes and structures. Depending on particle characteristics, functional films and bulk materials for thermal insulation, light diffusion, and electro conductivity can be obtained.

    Graphical Abstract Fullsize Image
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  • Noriaki NAGAI
    2019 Volume 27 Pages 63-69
    Published: May 25, 2020
    Released: May 25, 2020
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    Recently, many insoluble drugs were produced with progressing the search method of novel drug, such as the combinatorial chemistry and high through-put screening studies. Therefore, it is important to develop a technic to enhance the bioavailability of insoluble drugs. In this study, we prepared the nanocrystal based on crystal polymorph of cilostazol (CLZ), and found that the crystal polymorph affected the solubility, stability and bioavailability in the CLZ nanocrystal. In addition, we designed the oral formulation containing CLZ nanocrystal (CLZ/R-NPs tablet) by the combination of recrystallization and ball milling. The areas under the concentration-time curve (AUC) in rats orally administered CLZ/R-NPs tablet were significantly higher than that in OD tablets with CLZ powder (CLZ/R-MPs tablet), and the AUC levels of CLZ/R-NPs tablet was approximately 2-fold of CLZ/R-MPs tablet. In addition, the oral administration of CLZ/R-NPs tablets attenuated the neurological deficits caused by ischemic stroke in a cerebral ischemia/reperfusion-induced injury model (MCAO/reperfusion mice). It is possible that the oral formulation based on CLZ nanocrystal will be useful for the treatment of patients with ischemic stroke and that these findings will provide significant information that can be used to improve the drug with low bioavailability.

    Graphical Abstract Fullsize Image
    Frequency size distribution and SPM image of CLZ/O-NPs and CLZ/R-NPs.
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  • Erika NAWA
    2019 Volume 27 Pages 70-75
    Published: May 25, 2020
    Released: May 25, 2020
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    The human society has abundant and various environmental vibrations caused by working factories and running vehicles. Most of the vibrations are lost as thermal energy and are regarded as pollutions in our life. Recently, the technologies utilizing these environmental vibrations is developing.

    When a powder layer undergoes vertical vibration, the unique characteristic patterns appear depending on the frequency and amplitude of the vibration. Regarding theses pattern formations, the behaviors and the properties of the pattern formations have been investigated to understand the mechanisms. On the other hand, motion of objects on vibrating powder layer that may be applied for their transport remains less studied.

    In our research, objects with various structures on the powder layer with various particle size under the vertical vibration were observed. Moreover, the kinetic mechanism of the motion of the objects were considered from the relations between the behaviors of the powder and the objects.

    Graphical Abstract Fullsize Image
    The rotational motion of the line symmetry shape gear and point symmetry shape gear on the vibrating powder layer.
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  • Kenjirou HIGASHI
    2019 Volume 27 Pages 76-80
    Published: May 25, 2020
    Released: May 25, 2020
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    Amorphous nanoparticle composed of poorly water soluble glibenclamide (GLB) and stabilizer hypromellose (HPMC) was prepared by two antisolvent methods. In method A, DMSO solution containing GLB was poured into water containing HPMC to prepare nano-A suspension. In method B, a DMSO solution containing both GLB and HPMC was poured into water to obtain nano-B suspension. The morphology of nano-A and nano-B was spherical hollow and deformed non-hollow particles, respectively. The GLB amorphous was more stable in nano-A than in nano-B during heating process, because GLB and HPMC in nano-B was more miscible than in nano-A. The stability of the amorphous GLB in nanoparticles was strongly affected by GLB/HPMC miscibility, depending on their methods of preparation.

    Graphical Abstract Fullsize Image
    Schematic representation of precipitation process and structure of (a) nano-A and (b) nano-B.
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  • Atsushi HIRANO
    2019 Volume 27 Pages 81-86
    Published: May 25, 2020
    Released: May 25, 2020
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    Nanomaterials, including carbon nanotubes (CNTs), are coated by proteins in early stages of their uptake into biological systems. The protein layers around the nanomaterial surfaces are called protein corona, which determines the fate pathways and biological impacts of the nanomaterials. However, little is known about interactions of proteins with the nanomaterials during protein corona formation. In this work, we discovered that CNTs form thick and dense protein layers on their surfaces and induce oxidative stress on the proteins. The proposed protein oxidation mechanism will advance the fundamental understanding of the biological safety and toxicity of nanomaterials.

    Graphical Abstract Fullsize Image
    Editor’s picks

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  • Toshiyuki FUJIMOTO
    2019 Volume 27 Pages 87-93
    Published: May 25, 2020
    Released: May 25, 2020
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    By calculating trajectories of aerosol particles by Langevin dynamics method, in which random motion of aerosol particles are represented by pseudo random number, coagulation coefficient of aerosol was calculated. Both interval times between collision of one particle with other particles, and concentration distribution of particles were calculated in MTBC method: it was utilized to investigate the coagulation coefficient in transition regime. Coagulation coefficient obtained by the MTBC method corrected by concentration of particle at infinity are smaller than that obtained by flux matching method by Fuchs (1964). This suggests that the assumption made in the flux matching method does not hold completely. Then, in order to develop numerical model of change in particle size distribution by coagulation, GPGPU was employed to calculate the coagulation coefficient by parallel computing of motion of large number of particles.

    Graphical Abstract Fullsize Image
    Time evolution of inverse of particle number concentration due to coagulation by GPGPU calculation.
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  • Hiroshi FUDOUZI
    2019 Volume 27 Pages 94-100
    Published: May 25, 2020
    Released: May 25, 2020
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    We have been developing a new coating method for structural color film caused by colloidal crystal. Three-dimensional objects treated with hydrophilic surfaces were immersed in polystyrene colloidal suspension. Liquid film of colloidal suspension wetted for the objects’ surface and furthermore the liquid surface was covered with a silicone oil liquid. The objects pull out from the colloidal suspension at 60 μm/min rate and coated with colloidal crystal film showing with structural color. The color from blue to red has controlled with the size of the colloidal particle, interspacing of the particles and the refractive index of colloidal crystal film. In addition, our new coating method enables us to coat of high-quality colloidal crystal film on a three-dimensional surface having irregularities or curvature. At the lab level, a polystyrene suspension equivalent to 80 L was prepared and an A3 scale size coating was demonstrated. From a different viewpoint, the suspension can be recycled and a colloidal crystal can be formed at around room temperature. We believe this coating method environmental friendly process with low energy consumption. However, since the deposition rate of the colloidal crystal thin film is very slow, a practical coating process needs improvement.

    Graphical Abstract Fullsize Image
    Coating colloidal crystal film on the non-planar surface (call as Jewel beetle coating): A) Structural colors from blue to red by changing particle size, B) Film coating on curved and surfaces
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  • Motohide MATSUDA
    2019 Volume 27 Pages 101-105
    Published: May 25, 2020
    Released: May 25, 2020
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    In this study, the magnetic orientation behavior of K2NiF4 type layered Ni-based perovskite compound Ln2NiO4 (Ln = La, Pr and Nd), which has attracted much attention as a cathode material for low-temperature solid oxide fuel cells, was investigated. The final goal of this study is to develop effective process to fabricate oriented cathodes on electrolytes in a low magnetic field. According to our previous study, La2NiO4 can be oriented in a strong magnetic field of 12 T, but no orientation is made under a low magnetic field of 1 T or less. On the other hand, as a result of this study, it was found that, for example, PrNdNiO4 shown below was oriented in a low magnetic field of 0.9 T, leading to materials design for high performance electrode particles. In addition, the easy magnetization axis for PrNdNiO4 was the c-axis. Higher conductivity was obtained on the ab plane in conductivity measurements. From these results, it is shown that high performance oriented electrode of PrNdNiO4 can be fabricated by applying a low magnetic field parallel to the surface of electrolyte.

    Graphical Abstract Fullsize Image
    XRD patterns from the surfaces (a) perpendicular and (b) parallel to magnetic field applied for PrNdNiO4 bulk fabricated by slip-casting in magnetic field. For comparison, powder XRD pattern of PrNdNiO4 is shown on (c) in the figure.
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  • Yu MATSUDA
    2019 Volume 27 Pages 106-109
    Published: May 25, 2020
    Released: May 25, 2020
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    In the present study, we have studied the impact on a granular bed by a hydrogel sphere. The impact of an object will lead to the formation of a crater. The diameter of the crater is proportional to the 1/4 power of the kinetic energy of the object for low speed impact of a solid sphere. For a liquid drop impact cratering, some scaling factors (from 1/6 to 2/5) have been reported due to the complexity of a liquid drop impact phenomenon such as deformation, splashing, and penetrating granular bed. Considering only the effect of the deformation on the scaling relation, we investigated the impact cratering of a hydrogel sphere which deforms without splashing and penetrating. For spheres with high Young’s modulus, the relation of the 1/4 power law, which is reported for a solid sphere impact cratering, is observed. On the other hand, the power is smaller than 1/4 for the impact of the sphere with small Young’s modulus.

    Graphical Abstract Fullsize Image
    Dynamics of impact on granular bed.
    Editor’s picks

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  • Yasushi MINO
    2019 Volume 27 Pages 110-114
    Published: May 25, 2020
    Released: May 25, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    Filtration is widely used to separate or concentrate deformable particulate suspensions in various industrial processes. In the filtration process, particulate fouling, which causes a decrease in permeation flux, is generally inevitable. To design the filtration process for effective suppression of fouling, we must understand the fouling phenomena essentially. A numerical simulation is an effective approach to understand the fouling mechanism of deformable materials. In this study, a novel simulation model was developed, which enables to independently evaluate various factors influencing on membrane fouling and visualize the particle motion. The simulation of the cross-flow filtration of a deformable particle was conducted to investigate the effect of the particle deformability on membrane fouling. The simulation results demonstrate that the present model can reproduce the dynamics of deformable particle in the filtration process.

    Graphical Abstract Fullsize Image
    Effects of deformability on pore clogging behavior: (a) rigid particle, (b) deformable particle.
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  • Daigo YAMAMOTO
    2019 Volume 27 Pages 115-120
    Published: May 25, 2020
    Released: May 25, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    Liesegang phenomenon has been extensively studied experimentally and theoretically in the field of nonlinear science. However, there are few studies for its applications due to the high nonlinearity. The particles produced with the Liesegang phenomenon have been limited to microparticles of sparingly soluble salt for many years. In this study, in anticipation of more engineering application of this phenomenon, metal nanoparticles are synthesized by diffusing metal ions into a gel containing a reductant. At that time, we investigate the influence of diffusion conditions on particle formation. As a result, we found that the size of resultant particles depends on the gel position. Furthermore, we construct mathematical model expressing ion diffusion and particle growth based on Ostwald ripening to discuss the particle formation mechanism.

    Graphical Abstract Fullsize Image
    Snapshots of resultant bands and TEM images of metal nanoparticles formed in agar gels.
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  • Akira YOKO
    2019 Volume 27 Pages 121-125
    Published: May 25, 2020
    Released: May 25, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    First-principles calculations were conducted to study the possibility of the formation of SnTiO3. Nanocluster models were used, and BaTiO3 and SnTiO3 were studied. SnTiO3 was stabilized with Sn rich surface similar to the BaTiO3. Also, SnTiO3 has smaller surface energy than that of BaTiO3, suggesting the possibility of the formation of nanoparticles of SnTiO3 and stabilization of the unstable structure with nanometer-size. As a result of nanoparticle synthesis of BaTiO3, Ba deficient structure was elucidated. Under the condition, the synthesis of Sn-Ti composite oxide was studied.

    Graphical Abstract Fullsize Image
    Structure of A-site (Sn) surface rich SnTiO3 cluster.
    Editor’s picks

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  • Katsumi YOSHIDA
    2019 Volume 27 Pages 126-132
    Published: May 25, 2020
    Released: May 25, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    Ceramic-based fiber reinforced composites based on silicon carbide (SiC) and alumina (Al2O3) have been expected to be applied in the aerospace, environment and energy fields as next-generation highly reliable heat-resistant materials. The fiber/matrix interface in ceramic-based fiber reinforced composites plays an important role to develop excellent mechanical properties, and it is important to form optimal interface layers in the composites and to control the interface. The aim of this study is to develop the novel formation process of nano-scale coating layer (interfacial layer) with the thickness of several tens to several hundreds of nanometers on the surface of ceramic fibers (micro-scale substrate) by electrophoretic deposition (EPD) method, and the formation process of carbon coating layer and hexagonal boron nitride coating layer on the conductive and low-conductive SiC fibers by EPD was studied.

    Graphical Abstract Fullsize Image
    SEM micrographs of the surface of (a) as-received SiC fiber and carbon-coated SiC fiber by EPD using (b) 0.1 wt%, (c) 0.2 wt% and (c) 0.3 wt% colloidal graphite suspension.
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  • Satoshi WATANABE
    2019 Volume 27 Pages 133-137
    Published: May 25, 2020
    Released: May 25, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    The present study focused on the self-assembly of porous metal-organic framework (MOF) particles into spherical superstructures and characterization of structural and adsorption properties of fabricated superstructures, aiming at practical applications of MOFs in separation processes. Self-assembly was conducted by mixing MOF particles dispersed in MeOH-water mixture with fluorinated oil to make suspension droplets, followed by the drying. Spherical superstructures formed at a MeOH-water mixture volume ratio of 1 : 1 possibly because both the droplet and dispersion stabilities are enhanced. Porosity of superstructures was approximately 0.3, indicating that the structure is close to the close-packed one. Adsorbed amount in superstructures was less than in MOF power, although the adsorption rate is larger for a superstructure-packed bed than powder-packed one because gaps between superstructures act as meso/macro pores to promote mass transfer.

    Graphical Abstract Fullsize Image
    Schematic of experimental setup.
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