Award type：Award from international society, conference, symposium, etc.  Country：Taiwan, Province of China

researchmap

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

researchmap

Award type：Award from international society, conference, symposium, etc.  Country：Poland

researchmap

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

researchmap

researchmap

researchmap

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

researchmap

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

researchmap

researchmap

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

DOI： 10.1063/5.0055436

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jnnfm.2020.104385

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

<p>Complex fluids have a non-uniform local inner structure. The non-uniformity of polymer and worm-like micellar solutions were characterized by the local viscosity distribution obtained by optical tweezers with the inverse integral transformation method.</p>

DOI： 10.1039/d0sm00887g

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

The sedimentation and flow characteristics of micro-encapsulated phase change materials have been investigated. As a phase change material, trimethylolethane clathrate hydrate having 218 kJ kg(-1) of latent heat was used and encapsulated in silica hard-shell microcapsules, which size distribution has two peak at 15 mu m and 59 mu m. A cationic surfactant, oleylbishydroxyethylmethylammonium chloride with a counter-ion, sodium salicylate was used as drag reducing additives and poly vinyl alcohol was used as a stabilizer. From the results, it was found that the combination additive prevents effectively the microcapsule sedimentation. The drag reduction was also observed to occur in the high Reynolds number region. Thus, the present additive was concluded to be promising for the latent heat transportation by use of silica hard-shell microcapsules containing phase change materials. (C) 2019 Elsevier Ltd and IIR. All rights reserved.

DOI： 10.1016/j.ijrefrig.2019.07.007

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevfluids.4.074201

researchmap

Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevFluids.4.074201/fulltext

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

DOI： 10.1063/1.5096781

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ltd  

Ammonium alum hydrate is a promising material for a latent heat transportation system for higher temperature around 50 °C. However, there were two big problems to be solved. One is a low fluidity of the slurries due to increasing the viscosity
the other is a sedimentation of phase changed ammonium alum hydrate particles in the slurry due to high density of the particle, which causes pipe blockage. In this study, in order to solve these problems, we added drag reducing surfactants and polyvinyl alcohol (PVA) to the ammonium alum hydrate solution, and investigated the effects of them. Particle growth and sedimentation of ammonium alum in the solution were prohibited by adding both surfactants and PVA. Addition of only PVA to ammonium alum solution didn't prevent the particle growth and the sedimentation. That is, the effect was a synergetic effect. In order to understand the synergetic effect, inner structures of a solution containing surfactants and PVA were measured by a dynamic light scattering (DLS). Flow and heat transfer characteristics were also measured and analyzed. Friction coefficients of solutions and slurries were decreased with the drag reducing surfactants, which was not affected by addition of PVA. Heat transfer characteristics of ammonium alum hydrate slurries were higher than that of solution with surfactants and PVA. All the results confirmed the applicability of the ammonium alum hydrate slurries for the high temperature latent heat transportation systems.

DOI： 10.1016/j.ijheatmasstransfer.2018.04.030

Scopus

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

An experimental study was performed to investigate the relationship between the extensional rheological properties of polymer solutions and vortex deformation in turbulent flow. Polyethyleneoxide as a flexible polymer and hydroxypropyl cellulose as a rigid polymer are added to two-dimensional (2D) turbulent flow. Specifically, 2D flow is advantageous as it examines the effect of the extensional rheological properties of polymers on the flow. In the study, 2D turbulent flow and vortex shedding in 2D turbulent flow were observed using interference patterns and particle image velocimetry (PIV). Power spectrum of the 2D flow images and 2D turbulence statistics calculated by PIV analysis indicated that there are three flow regimes of vortex shedding in the 2D turbulent flow of the polymer solution. The vortex shedding in the 2D flow was categorized into three types, and this was affected by the relaxation time of the polymer solutions.

DOI： 10.1016/j.jnnfm.2018.02.001

Scopus

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society of Rheology  

Extensional flow properties of dilute viscoelastic solution have attracted much attention for almost three decades. This is because extensional viscosity or relaxation time of viscoelastic solution under extensional stresses add a lot of impact on fluidity of the solution
the phenomenon is related to many industrial applications. Several techniques were proposed and many studies were conducted to measure extensional properties of polymer solutions. However, less studies were reported in the case of non-uniform solution, such as suspensions. In this study, we propose a relatively simple method to measure extensional viscosity. We adopt a syringe-shape abrupt contraction channels for the measurement
the syringe-shape apparatus is useful to contain non-uniform dilute solutions. As a first step to develop the experimental apparatus and method, we tested polymer solutions. Polymers used to prepare sample solutions were polyethylene oxide (PEO), hydroxypropyl cellulose (HPC) and polyacrylic acid (PAA). Each polymer has different flexibility, which cause different characteristics of the extensional viscosity of polymer solutions. Extensional viscosities obtained in this study detected the characteristic of each polymer solution. Extensional viscosities of PEO solution was increased by increasing extensional rates
that of HPC and PAA solution were decreased by increasing extensional rates
the tendency was explained by relaxation times of each polymer solution.

DOI： 10.1678/rheology.46.13

Scopus

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：SOC RHEOLOGY, JAPAN  

Fluidity of complex fluids such as dilute polymer solutions and threadlike micelle solutions is highly affected by its inside structure. The complexity of the fluid is that a key factor affecting the fluidity can be different at each length scale. We have been trying to investigate effects of polymers on turbulent drag reduction. In order to extract effects of extensional rheology of polymer solutions on a turbulent flow, we use wall-free two-dimensional(2D) turbulence. 2D turbulence was visualized and analyzed by interference patterns of the flow and PIV analysis. Polymers were found from the results to induce vortex deformation, which prohibits the energy transfer in the 2D flow. The phenomena were significantly affected by a relaxation time of polymer solution. We also studied effects of mixed solution of polymers and threadlike micelles on fluidity and on a sedimentation phenomenon of latent-heat fine particles in a latent heat transportation system. At a certain concentration, the particles were highly dispersed for several days. Inner structures of the solution were measured by a dynamic laser scattering system, which indicated the combined effects of polymers and threadlike micelles.

DOI： 10.1678/rheology.45.225

Web of Science

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

In order to investigate a fouling mechanism, adhesion behavior of a calcium carbonate particle onto various walls having different hydrophilic/hydrophobic characteristics have been studied. First, adhesion force was measured by atomic force microscope, which decreases with hydrophilicity of walls. Second, fouling phenomena on each plate was measured over time. In the case of the hydrophobic surface, bare copper plate, adhesive calcium carbonate crystal was increased, and the amounts reached the constant values. On the other hand, in the case of the hydrophilic surface, glass plate and hydrophilic coated copper, calcium carbonate crystal was adhered for several hours, then the crystal was removed from the plates. Crystal types of calcium carbonate on each plate were also analyzed by a X-ray diffractometer. The crystal type was varied due to the hydrophilic/hydrophobic characteristics of the plates. From the results, it was expected that the hydrophilic treatments to wall surfaces in heat exchanger might be useful to control fouling phenomena. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijheatmasstransfer.2015.08.068

Web of Science

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

In order to study the effects of extensional viscosities on turbulent drag reduction, experimental studies using two-dimensional turbulence have been made. Anisotropic structures and variations of energy transfer induced by polymers are considered. Polyethyleneoxide and hydroxypropyl cellulose having different flexibility are added to 2D turbulence. The different flexibility induces different characteristics of extensional viscosity. In addition, since increases of the extensional viscosity also depends on extensional rate, different extensional rate are added to the flow. Variations of the turbulence are visualized by interference patterns of 2D flow. The interference patterns are analyzed by 2D Fourier transform to detect effects of polymers in the streamwise and in the normal directions. Scaling exponent of power spectrum of the interference patterns indicate how energy transfer was changed by polymer additives. The energy transfer was also discussed by velocity field measured by PIV analysis. Wavelet transform are also applied to detect variations of characteristic scales in 2D turbulence.

DOI： 10.1007/s10494-015-9647-8

Web of Science

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

An experimental study has been performed to investigate the relationship between the extensional viscosity of polymers and the turbulent drag reduction. Self-standing flowing soap film was used to generate two-dimensional (2-D) turbulent flow to eliminate shear stress. Two types of polymers having different flexibilities were added to the 2-D turbulence. The effects of these polymers were visualized by the interference pattern of flowing soap films. The vortex deformation by adding polymers was analyzed by Fourier transformation and wavelet transformation. The scaling exponents of the power spectrum of interference patterns indicate that the mechanism of turbulence laminarization due to the extensional viscosity is anisotropic. A wavelet analysis reveals the high and low fluctuations of the polymer-added flow. Results from wavelet analysis indicate disappearing of original vortices, and appearing of new structures in low frequency in 2-D flow. (c) 2014 American Institute of Chemical Engineers AIChE J, 60: 1854-1862, 2014

DOI： 10.1002/aic.14364

Web of Science

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

Aluminum ammonium sulfate dodecahydrate (ammonium alum hydrate) slurries are promising latent heat media for high temperature applications. However, a major problem associated with materials developed specifically for high temperature use is sedimentation in the pipes of the device. Thus, the ability of poly vinyl alcohol (PVA) to prevent sedimentation and particle growth of ammonium alum hydrates has been investigated in this study. In order to increase the fluidity of the slurry, a cationic surfactant, behenyl trimethyl ammonium chloride, was used as a drag-reducing agent, and the interaction between the cationic surfactant and PVA was evaluated. The rheological properties of the slurries and solutions were investigated, and they indicated that the drag-reducing cationic surfactant was not disturbed by the PVA.

DOI： 10.1252/jcej.13we085

Web of Science

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

An experimental study has been performed to investigate the relationship between the extensional viscosity of polymers and the turbulent drag reduction. In order to obtain the flow which is mostly dominated by extensional flow, two-dimensional (2D) grid turbulence made by flowing soap films was used. Extensional rate added to the flow was controlled by changing the conformation of the grid. Polyethylene oxide, as a flexible polymer, and hydroxypropyl cellulose, as a rigid rod-like polymer were added to the flow. Several extensional rates affect polymer behaviors, which induce different effects. Drag reduction effects of polymers under several extensional rates were visualized and analyzed by image processing. Rheological properties of the polymer solutions were also measured by a rheometer. The results indicated that the mechanisms of energy transfer are different in the streamwise and normal directions. The critical concentration to observe drag reduction effects in 2D turbulence was changed by the extensional rate. When extensional rate is higher, the effects were started to observe from lower concentration. These results were confirmed to correspond to the drag reduction effects obtained by classical pressure drop experiments in a pipe flow.

DOI： 10.1007/s00397-013-0733-3

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Two-dimensional turbulence in flowing soap films with polymer additives is analyzed by image analysis. The power spectra of the interference patterns of turbulent soap films are calculated. The scaling exponent of the power spectrum is -5/3 for polymer free solution and -1 for dilute polymer solution in enstrophy cascade range, which is consistent with the results of thickness fluctuations in previous researches. We propose a Curvature analysis method that calculates the curvatures of the interference pattern of turbulent soap films. The results suggest that the curvature histogram describes well the shape of the interference pattern, which is related to the shape of the vortices. The curvature histograms for different polymer concentrations can be fitted by a stretched exponential function.

DOI： 10.1007/s00348-010-0850-z

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijrefrig.2023.05.001

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1678/rheology.51.157

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Publishing type：Research paper (scientific journal)  

This paper reports the selective fabrication of a zeolitic imidazolate framework-8 (ZIF-8) cover layer over the outer surface of silica hard-shell microcapsules (HSMC) to improve the microencapsulation technique of phase change materials for heat storage materials. ZIF-8 was formed not only over the HSMC but also in the synthesis solution side when using a conventional batch operation owing to the rapid formation rate of ZIF-8 in the aqueous solution at 293 K. In this study, a semi-batch operation, which can control the concentration of the components in the synthesis solution by gradually dropping the components, was employed to decrease the formation rate of ZIF-8. X-ray diffraction results suggested that dropping ingredients strongly affected the obtained products; the addition of the Zn2+ aqueous solution into a 2-methylimidazole (Hmim) aqueous solution was suitable for the formation of ZIF-8, whereas the addition of an aqueous solution of Hmim into the Zn2+ aqueous solution formed Zn hydroxides as unfavorable by-products. Field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy results confirmed that the semi-batch operation with the addition of Zn2+ into the Hmim aqueous solution selectively formed a ZIF-8 cover layer over the HSMC. We conclude that the semi-batch operation is an effective procedure for suppressing the unfavorable homogeneous nucleation on the solution side and making heterogeneous nucleation dominant without any additives to fabricate the ZIF-8 cover layer.

DOI： 10.1039/d2ce00488g

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.ijrefrig.2022.05.017

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.ijrefrig.2022.03.020

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jciso.2021.100038

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society of Rheology Japan  

DOI： 10.1678/rheology.50.297

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.18462/iir.PCM.2021.1934

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society of Chemical Engineers, Japan  

DOI： 10.1252/jcej.19we159

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Society of Chemical Engineers, Japan  

DOI： 10.1252/jcej.19we123

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Society of Chemical Engineers, Japan  

DOI： 10.1252/jcej.19we151

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/aic.16780

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/aic.16780

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijrefrig.2019.01.026

researchmap

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.cherd.2018.12.022

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Begellhouse  

DOI： 10.1615/IHTC16.ecs.022594

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1615/IHTC16.ecs.022545

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Electrochemical Society  

DOI： 10.1149/2.0111904jes

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1615/IHTC16.ecs.022579

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1051/matecconf/201819704005

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：International Institute of Refrigeration  

For effective use of excess exhaust heat from gas engines, a novel PCM was prepared by adding anhydrous sodium sulfate and D-mannitol to ammonia alum hydrate. It melted and stored latent heat at the temperature range of exhaust heat from gas engines (around 90°C). Heat storage and release characteristics of the novel PCM were investigated with a heat storage tank containing hot water and the novel PCM packaged into resin bags. As a result, the novel PCM stored and released more than 400 MJ×m-3 of heat at the temperature range between 80°C and 90°C. The amount of heat storage and release by the PCM was approximately ten times higher than that of water with same volume. This result indicates that the novel PCM can reduce the volume of hot water tank dramatically in addition to storing and releasing exhaust heat from gas engines.

DOI： 10.18462/iir.pcm.2018.0029

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society of Rheology  

In order to clarify the mechanism of the bulge structure appearance observed in a cavity swept by a visco-elastic fluid, velocity fields were measured by a two-dimensional particle image velocimetry (PIV). The rib height, the cavity length, the flow path height and the flow path width were fixed at 20 mm, 100 mm, 40 mm and 75 mm, respectively. The Reynolds number was also fixed at 1,700 where the bulge structure appeared as reported by the previous study. The spanwise positions of the two-dimensional PIV were changed in 6 steps from the center plane to the outer region. From the results, it was found that the bulge structure has high-level fluctuation and its intermittency is related to the longest relaxation time. The bulge structure appears when the main flow separated from the upstream top corner of the cavity is intensified. The separated main flow contracted in the former cavity region expands not only toward the cavity bottom but also toward the outside walls of the flow path. In order to supply the fluid in the center plane, the backward flow occurs in the cavity. This flow motion was concluded to be a basic mechanism of the bulge structure appearance.

DOI： 10.1678/rheology.46.29

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：International Institute of Refrigeration  

To investigate the sedimentation and flow characteristics of hard-shell microcapsule/water slurries, the apparent viscosity, apparent dispersion volume fractions, and friction characteristics were measured. The hard-shell microcapsule contains disodium hydrogen phosphate hydrate as a phase change material. Poly (vinyl alcohol) (PVA) with a concentration from 0 to 2,000 ppm was applied as a dispersant. A drag-reducing surfactant system was also added to the slurries to improve the flow characteristics of the slurries. As a drag-reducing surfactant, oleylbishydroxyethylmethylammonium chloride was added at 2,000 ppm with a counter-ion of sodium salicylate. As a trial, the concentration of microcapsules was set at a low value at 1 or 2 wt%. From the results, severe adsorption of surfactants onto the hard-shell microcapsules was found. Then, no drag reduction or sedimentation prevention occurred in the cases without PVA. However, there is a weak sedimentation prevention effect and effective drag reduction effect when PVA is present. Thus, it is concluded that the desorption of surfactants from the microcapsules occurs and forms a synergetic structure with the PVA.

DOI： 10.18462/iir.pcm.2018.0023

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Society of Chemical Engineers, Japan  

We previously reported that a rotationally reciprocating impeller, which slowly rotates back and forth with a sinusoidal change in the rotational speed, can realize superior mixing performance even under moderate fluid flow. In the case of crystallization process, it is expected that the rotationally reciprocating mixing suppresses crystal brakeage caused by collision to impeller plate and inhomogeneous supersaturation due to notable mixing performance. In the present study, we studied reactive crystallization process of salicylic acid and investigated the effect of mixing conditions on the size and shape of crystals. For a steady rotational mixing, the largest crystal size was obtained at the appropriate mixing condition, and the size and shape of crystals are both affected by the rotational speed. Meanwhile, it is found that the size of crystals maintained roughly constant in the wide range of mixing condition of the rotationally reciprocating mixing. Additionally, no significant difference in the shape was observed even at different reciprocating conditions.

DOI： 10.1252/jcej.17we015

Scopus

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The fabrication method of silica hard shell microcapsules containing disodium hydrogen phosphate dodecahydrate (Na2HPO4 center dot 12H(2)O) has been developed. The effects of the mixing rates for the emulsification, of the volume ratios of solutions and of surfactant concentrations on the size of hollow microcapsules have been also studied. From the results, it was confirmed that silica hard shell microcapsules can contains Na2HPO4 center dot 12H(2)O with the present method using hollow microcapsules. The present micro-encapsulated Na2HPO4 center dot 12H(2)O was also found to cause the supercooling depression effect. As the fabricated microcapsules have no flammability, the present microcapsule was concluded to be a promising item not only for latent heat transportation media but also for the static thermal storage materials for architectural structures. From the studies on the fabrication parameters, it was concluded that the control of the surfactant concentration is effective for controlling the size of microcapsule. (c) 2017 Elsevier Ltd and IIR. All rights reserved.

DOI： 10.1016/j.ijrefrig.2017.06.036

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Society of Powder Technology, Japan  

The structural change during particle dispersion process of highly concentrated slurries of PMMA and graphite particles was investigated in terms of viscoelasticity. PMMA particles having weak interaction are easy to be dispersed, and a higher shear rate was preferable for stable dispersion. In contrast, aggregated graphite particles generate sedimentation layer. Therefore, non-uniform slurry was obtained at the lowest shear rate, while the formation of network of aggregated graphite particles resulted in a highly viscoelastic slurry when dispersing at higher shear rates. Additionally, it was considered that the particle dispersion is completed at the shear rate, when the loss moduli of slurry and dispersing medium showed the same frequency dependence.

DOI： 10.4164/sptj.53.371

CiNii Books

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

The present study deals with the flow field in the circular cross section of a cylindrical vessel induced by a rotationally reciprocating impeller, rotating back and forth with gradual change in rotational speed. A periodically stable velocity field was measured by PIV and also simulated by CFD. It was revealed that the velocity field near the liquid free surface is basically 2-dimensional, except for the acceleration period at Re = 43, and agrees well with 2-dimensional CFD simulation, except for the development process of 3-dimensional tip vortices at Re = 43. The separation behavior of the vortices originally generated at the impeller tip changed with increasing Reynolds number. No separation was observed at a lower Reynolds number, while the separated vortices turn into 3-dimensional potential vortices and remain as 2-dimensional vortices at the next impeller counterturn at higher Reynolds numbers. The fluctuation of each velocity component was remarkably small, suggesting that the flow field even at the highest Reynolds number was still laminar. It is found that effective transportation of energy from the impeller to 3-dimensional potential vortex is related to a large and constant power number, which is reported in our recent publication.

DOI： 10.1252/jcej.15we040

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC RHEOLOGY, JAPAN  

A flow experiment of a dilute suspension and aggregation/dispersion analysis of fine particles in a non-uniform shear field were performed. We investigated the dispersion characteristics in a microchannel with an abrupt contraction section. The dispersed particles and dispersion media were polystyrene and aqueous glycerine, respectively. The particle diameter and solid volume fraction were 3.5 mu m and 0.001, respectively. Citric acid (0.5 and 1.0 wt%) was added as a non-ionic salt in order to investigate the effect of the aggregational force. The suspension was introduced into the microchannel with a syringe pump at a volume rate of 0.3 mu l-min(-1). The aggregation/dispersion characteristics of the fine particles were observed with a microscope and analyzed by image analysis. We observed the breakup and re-aggregational behavior of the fine particles in a dilute suspension. The cumulative frequencies of fine particles fluctuated through the channel. From the results, we posit the possibility that the non-uniformity of ions affect the aggregational characteristics of fine particles in a shear flow.

DOI： 10.1678/rheology.44.153

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INT INST REFRIGERATION  

A novel fabrication technique of hard-shell microcapsules (HSMC) containing trimethylolethane hydrate as a phase change material has been tested with a double nozzle method. The inner and the outer diameters of the inner nozzle and the inner diameter of the outer nozzle of the double nozzle were fixed at 0.24, 0.46 and 0.8 mm, respectively. The inner/outer flow ratio was changed from 2.50 to 5.00, while the flow rate injected from the outer nozzle was kept constant at 2 ml/h. From the results, it was found that the mean diameter of capsules is 1.58 mm when the flow rate ratio is 2.50. In this case, a reasonable latent heat was also obtained. Thus, it was concluded that the present method for the fabrication of the capsules containing the trimethylolethane hydrate can be a promising method.

DOI： 10.18462/iir.pcm.2016.0029

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC RHEOLOGY, JAPAN  

An experimental study has been performed in order to investigate the optimum rheological characteristics for a technique of heat transfer augmentation in a cavity between ribs mounted in parallel plates. The rheological characteristics of visco-elastic fluid were changed by controling the molar ratio of counter-ion to a cationic surfactant. Flow visualization experiments and pressure loss measurements were conducted in the range of solvent Reynolds number from 100 to 2,500 and in the range of molar ratio from 0.50 to 10. Under this condition, the zoro-shear Reynolds number and the Weissenberg number ranged from 2.01 to 120 and from 1.94 X 10(-2) to 9.15, respectively. From the results, flow penetration into the cavity occurred in the cases from 1.5 to 5.0 of molar ratio of counter-ions. However, the pressure loss became large in the cases when the remarkable Barns effect can be observed. On the other hand, the pressure loss became almost the same as that of water in the case when the molar ratio of counter-ions was set at 5.0. From this, it was concluded that the optimum fluid for the heat transfer augmentation in a cavity is required to have suitable elasticity and low viscosity as the molar ratio of counter-ions is set around 5.0.

DOI： 10.1678/rheology.44.143

Web of Science

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INT INST REFRIGERATION  

The effect of the size of a combination structure of poly(vinyl alcohol) (PVA) as a stabilizer and drag-reducing surfactants in water on the sedimentation of particles of phase change materials (PCMs) in solutions was investigated. Behenyl trimethyl ammonium chloride was used as a surfactant with a 1.5 molar ratio of sodium salicylate as a counter-ion supplier at a constant surfactant concentration of 2,000 ppm in water, while the concentration of PVA was varied from 0 to 2,000 ppm. The structural size of the combined PVA and surfactant was measured with a dynamic light scattering (DLS) system. DLS analysis indicated that a large structure is formed by the interaction between PVA and surfactants. In addition, this structure becomes larger with the PVA concentration, and the occupation volume of the structure expands widely in a fluid. Thus, it was concluded that this large structure formation could cause an effective reduction of particle sedimentation in latent heat systems.

DOI： 10.18462/iir.pcm.2016.0019

Web of Science

J-GLOBAL

researchmap

Language：Japanese   Publisher：The Society of Rheology, Japan  

DOI： 10.1678/rheology.44.117

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1299/jsmeicope.2015.12._ICOPE-15-_37

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

A large plate impeller was rotated back and forth in a cylindrical vessel. Simultaneous and continuous measurements of the rotational torque on the mixing shaft and impeller angular position were carried out. The power consumption was computed by integrating the product of the measured torque and impeller rotational speed. The relationship between the power number and Reynolds number revealed that the Reynolds number became small for the transition in power characteristics and that the constant power number became large for the larger Reynolds number region at a small reciprocating amplitude with a large impeller acceleration. This is because a more remarkable startup flow was frequently repeated. The larger power number suggests that the rotationally reciprocating impeller has more efficient power characteristics compared to common rotational impellers. In terms of the torque variation, the measured torque was mainly dominated by the viscous force in the smaller Reynolds number region. As the Reynolds number increased, the phase lag between the torque and impeller speed increased even in the smaller Reynolds number region, and the measured torque was observed to fluctuate in the transition region. Although the measured torque was mainly dominated by the inertia force, the phase lag and magnitude of fluctuation did not increase any further at large Reynolds numbers.

DOI： 10.1252/jcej.14we392

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

Flow characteristics of visco-elastic fluids sweeping a one-side micro-cavity mounted in a micro-duct have been investigated in order to develop a novel technique of a mixing process for micro-reactors. In this paper, effects of the Reynolds number and of the rheological characteristics of the fluids were focused on. The cavity depth, the cavity length and the width of the wider flow path were fixed at 200, 1,000 and 400 gm, respectively. As a visco-elastic fluid, a solution of cationic surfactants with counter-ions was used. The molar ratio of counter-ions to surfactants was changed in four steps in order to change the rheological characteristics of the visco-elastic fluids. The Reynolds number was also changed from 0.100 to 100. From the results, it was found that a tonguing motion of the separation fluid bubble tip formed in the downstream region in the cavity occurs at a certain Weissenberg number larger than 200 due to the elastic instability. The fluctuating bulge structure was also observed on the upstream side wall of the cavity in a higher range of the Weissenberg number. Such a elastic instability can be expected a suitable micro-fluid motion for the micro-mixing. (C) 2015 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.expthermflusci.2015.02.025

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer New York LLC  

Particle aggregates formed in a dispersing medium may be destroyed depending on the shear history applied in the coating process. Yielding behavior of gelled-clay particle dispersion can be interpreted as the destruction of particle network structure with the increase in shear strain. In the present study, gelled-clay particle dispersion was coated at different shear strain to control the initial status of particle aggregation of the drying process. The packing behavior of clay particles in the coated film was investigated from the viewpoint of void fraction in the film by the simultaneous measurements of weight loss and thickness decrease. Additionally, the change of surface roughness was researched based on the scattering pattern analysis. As a result, it was found that dispersed particles started to be packed tightly in the constant drying rate period, and that void fraction and surface structure of particle-packed layer scarcely changed in the latter part of the falling drying rate period. In contrast, if clay particle aggregates remained at the beginning of drying, a loosely packed particle layer was formed without changing surface structure in the constant drying rate period. However, the surface roughness was increased continuously in the falling drying rate period in spite of keeping constant film thickness, probably because void in the particle layer was collapsed.

DOI： 10.1007/s11998-015-9719-7

Scopus

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Inertio-elastic instability characteristics of visco-elastic fluids sweeping a micro-cavity mounted in a micro-duct have been investigated in order to develop a effective micro mixer. The cavity depth, the cavity length and the width of the wider flow path were fixed at 200, 1,000 and 400 μm, respectively while the solvent Reynolds number was changed from 0.100 to 100. As a visco-elastic fluid, a cationic surfactant/counter-ion system was applied. The molar ratio of counter-ion to surfactant was changed from 1.5 to 10 in order to control rheological characteristics of the fluid. Flow visualization experiments were performed with a high-speed camera mounted on a microscope. From the results, it was that a tonguing motion of the separation fluid bubble tip formed in the downstream region in the cavity occurs at a certain Weissenberg number larger than 200 due to the inertio-elastic instability. The fluctuating bulge structure was also observed on the upstream side wall of the cavity in a higher range of the Weissenberg number. These characteristics were considered to be effective for a mixing process. It was also found that the separation bubble size is determined with Weissenberg number for all fluids treated in this study, but the previous correlation suggested for a macro-scale system does not agree with the present results. This indicated that some different relaxation structure exists in a micro-scale system.

DOI： 10.1299/transjsme.14-00650

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：begell house. inc. publishers,  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：begell house. inc. publishers,  

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society of Mechanical Engineers  

Flow behaviors of sodium hyaluronate (HA-Na) in water solution and in phosphate buffered saline (PBS) solution as a viscoelastic fluids in planer abrupt contraction-expansion channels has been observed in this study. Especially, the effect of the geometry of the flow path on the flow behavior was focused on. The corner vortices in the corner of the upper region in the abrupt contraction-expansion channels were also analyzed to quantify the flow characteristics. The elasticity numbers of the solution, which is affected by rheological properties of the solution and the channel geometry had a big influence on the fluidity, that is, stable or unstable, when the concentration of the solution in lower. It was concluded that such stable and unstable flows are categorized on Wissenberg-Reynolds number space.

DOI： 10.1115/AJKFluids2015-18556

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC RHEOLOGY, JAPAN  

Two-dimensional numerical computations of unsteady flow of a suspension between two coaxial cylinders are performed. We investigate the dispersion characteristics based on a novel thixotropy model. The diameter of particles, solid volume fraction, and viscosity of dispersing media are set to 2.5 mu m, 0.15, and 195 Pa.s, respectively. The shear rate is suddenly changed from 0.1 s(-1) to 1 s(-1). For model validation, the numerical results are compared with previously reported experimental results. The mean number of particles in a cluster increases slightly shortly after the shear rate change, reaches a maximum, and subsequently decreases, finally attaining a steady state at 40 s after the shear rate change. Our model better expresses the time variation of the dispersion characteristics than the previous model. After the validation, the effect of bonding energy on the time-variation characteristics is investigated. The bonding energy is varied as 2.7 x 10(-13), 2.7 x 10(-12), and 2.7x10(-11) J. We observe that the asymptotic values of the mean number of particles in a cluster depend on the bonding energy, but this relationship is not linear. From our results, we posit the existence of a certain critical bonding energy with regard to the dispersion characteristics.

DOI： 10.1678/rheology.43.85

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：International Institute of Refrigeration  

The fabrication of silica hard shell microcapsules containing disodium hydrogen phosphate dodecahydrate has been developed. The effects of the mixing rate and time to emulsification of solutions added by a homogenizer, volume ratio of solutions and of surfactant concentration on the size of porous hollow microcapsule have been studied. From the results, it was found that the effect of mixing conditions and of the volume ratio is rather small compared with that of surfactant concentration in the present range. Thus, it was concluded that the control of the surfactant concentration is effective for controlling the size of microcapsule. It was also found that the containing ratio of disodium hydrogen phosphate dodecahydrate is smaller than the void fraction of microcapsules. This was considered partially due to the microcapsule agglomeration and partially to hydrogen desorption through the shell during of the reaction. The supercooling depression in the microcapsules was also found in this study. Thus, the present microcapsule was concluded to be a promising item not only as latent heat transportation media but also as static thermal storage materials.

DOI： 10.18462/iir.icr.2015.0394

Scopus

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A fabrication process via the double-emulsion method is proposed for silica hard-shell microcapsules (HSMCs) that contain trimethylolethane (TME) hydrate. The TME-encapsulating silica-HSMCs are promising materials for reusable phase-change materials for latent-heat transportation systems. The obtained silica-HSMCs were visualized by a scanning electron microscope. The amount of TME hydrate inside the capsules was confirmed using a differential scanning calorimeter. The measured latent heat of the TME-encapsulating silica-HSMC was a reasonable fit to the predicted value.

DOI： 10.1246/cl.140099

Web of Science

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Part of collection (book)   Publisher：Springer-Verlag Wien  

Latest high-strength gels overcome brittleness due to the inhomogeneities built in their network structure. However, the inhomogeneities still prevent precise characterization of their network structures by scattering methods. A new concept is to take advantage of the ensemble-averaged structure characterization with scanning microscopic light scattering (SMILS), in order to study the network structure and properties of inhomogeneous high-strength gels nondestructively in wide spatio-temporal ranges. In this study, two kinds of the jungle-gym type polyimide gels that have semi-rigid main-chains or rigid main-chains were synthesized in varying the preparing concentration and studied with SMILS. The optimal concentration of polyimide achieved ten times higher Young modulus than before.

DOI： 10.1007/978-3-7091-1571-8_12

Scopus

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Part of collection (book)   Publisher：Springer-Verlag Wien  

An experimental study has been performed in order to investigate the relationship between the extensional viscosity of polymer solution and the turbulent drag reduction. A flexible polymer and a rigid rod-like polymer were added to the two-dimensional turbulent flow that was visualized by the interference pattern of a flowing soap film and analyzed by a single-image analysis. The power spectra of interference images were obtained, which is related to the water layer fluctuations in turbulence. The power spectra show a scaling behavior and the power components give the information of drag reduction. It was suggested that the energy transfer mechanisms are different in streamwise and normal directions. In the normal direction, the energy transfer was prohibited by the orientation of polymers, while the energy transfer in the streamwise direction was prohibited by extensional viscosity of polymers. The extensional viscosities of polymer solutions were measured by calculating pressure losses at an abrupt contraction flow.

DOI： 10.1007/978-3-7091-1571-8_18

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

In order to study a bulge structure observed in a cavity swept by a viscoelastic fluid, flow visualization experiments have been performed. The cavity depth, the cavity length and the width of flow path were fixed while the water Reynolds number based on the narrow flow path was changed from 680 to 4,200. From the results, the bulge structure formed on the upstream backward-facing side wall of the cavity in the mid-range of the Reynolds number was found to lead a fresh fluid into a cavity and to sweep the fluid near the cavity bottom wall. The bulge structure fluctuates very slowly and this fluctuation induces a tonguing motion of the tip of the separation bubble formed in the downstream region of the cavity. Thus, this structure can be expected to enhance the heat transfer from the cavity bottom.

DOI： 10.1088/1742-6596/530/1/012055

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

This study deals with fluid mixing process in the circular cross-section of a cylindrical vessel using a rotationally reciprocating (back and forth rotation) plate impeller from the view point of experimental visualization and numerical simulation. We have investigated the fluid deformation process with the visualization of streak lines. It has been found that a pair of vortices generated at the impeller tip plays a crucial role in stretching and folding of streak lines. Additionally, for effective overall mixing, we found that fluid needs to be dragged inward to the region near the mixing shaft, stretched and folded along the impeller plate, and then extensively deformed from the impeller tip. However, since the path of fluid inward motion is rarely disturbed by locally strong vortices generated at the conditions of small amplitude and short period, a poor mixing region expanded from the mixing shaft to the vessel wall, which made two separated mixing regions in a vessel. With increasing amplitude, the poor mixing region shrunk near the mixing shaft. In the case of the largest amplitude and longest period, fluid was effectively deformed everywhere in the vessel, which leads to a highly intensified mixing process.

DOI： 10.1252/jcej.13we081

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

The characteristics of oxygen dissolution accelerated by the use of micro-bubbles in a viscoelastic fluid were studied. An aqueous solution of a combination of a cationic surfactant and of a counter-ion supplier was used as a viscoelastic fluid. Flow visualizations and measurements on the time variation of the oxygen concentration were performed. From the results, it was found that the dissolution of oxygen rapidly occurs by the use of microbubbles, but the dissolution becomes slow in a highly elastic fluid. The flow observation of bubbles in a highly elastic fluid showed a chaining effect with bubble ascension. Bubble chaining was found to accelerate the agglomeration of bubbles and decrease the apparent gas-liquid interface area. Thus, such a chaining effect was concluded to disturb the dissolution of oxygen.

DOI： 10.1252/jcej.13we106

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

In order to study the effects of extensional viscosities on turbulent drag reduction, experimental studies using two-dimensional turbulence have been made. Anisotropic structures and variations of energy transfer induced by polymers are considered. Polyethyleneoxide and hydroxypropyl cellulose having different flexibility, which is due to different characteristics of extensional viscosity, are added to 2D turbulence. Variations of the turbulence were visualized by interference patterns of 2D flow, and were analysed by an image processing. The effects of polymers on turbulence in the streamwise and normal directions were also analysed by 2D Fourier transform. In addition, characteristic scales in 2D turbulence were analysed by wavelet transform.

DOI： 10.1088/1742-6596/530/1/012065

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC RHEOLOGY, JAPAN  

Aluminum ammonium sulfate dodecahydrate (ammonium alum hydrate) slurry is a promising latent heat medium for high-temperature systems. However, there exist the significant issues with this medium at high temperature with respect to crystal agglomeration, growth, and sedimentation. Therefore, the effects of adding drag-reducing surfactants and poly vinyl alcohol (PVA) on the formation process of ammonium alum hydrates crystals under a controlled shear flow have been investigated in this study. In addition, in order to investigate the impact of the surface hydrophilicity and hydrophobicity of cooling walls on the crystal growth, a copper plate and a silica coated copper plate were used as the substrates of the wall. From the results, it was found that the mean crystal size of the ammonium alum hydrate decreased with increasing shear rates and with the addition of surfactants and PVA. In addition, the crystals on the silica coated copper plate were smaller than those on the copper plate without a coating. Thus, the addition of drag-reducing surfactants and PVA and use of a hydrophilic surface prevented the crystal agglomeration and crysal growth of the ammonium alum hydrate under a shear flow. Furthermore, the viscosity of each solution was also measured, as affected by the various additives and by crystal agglomeration and growth.

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Hydrogels have low frictional properties, permeability and biocompatibility thanks to their high water content. However the problem of common gels is their brittleness as industrial materials. In the last decade, several high-strength gels have been developed, promising for applications of gels as new smart industrial materials. Here we study the smartness of novel ultrahigh ductile gels having Inter-Crosslinking Network (ICN), focusing on mechanical properties and structure. Three types of mesh densities of the ICN gels were experimentally determined from the size of internal structure, water content and Young's modulus of tensile test. By comparing the three mesh densities, the relation between the network structure and mechanical properties of the gels is possibly discussed. The new way to evaluate the ductility of the ICN gels was also introduced on the analogy of the small-world network model. The effect of the degree of polymerization on the ductility was discussed.

DOI： 10.1299/jmmp.7.245

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1299/jmmp.7.163

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Gels are soft and wet materials, which have unique properties such as low surface friction, material permeability, and biocompatibility. These superior properties of gels can possibly be applied to develop novel artificial blood vessels and can also be used at knee joints. However, the mechanical properties of the gels have not been clarified and controlled so far due to the lack of standard type of gels for mechanical engineering research. Here we try to develop a novel type of gel named the standard gel engineering materials (standard GEM) via simple bulk polymerization, <I>i.e</I>. dry synthesis without any solvent. In the numerous previous studies of gels, almost all gels have been prepared by solution polymerization, <I>i.e</I>. wet synthesis with various solvents. The mechanical properties of the wet-synthesized gels, however, strongly depend on the concentrations of the monomer, crosslinker, initiator, and accelerator in pre-gel solutions. Therefore, it is difficult to control the mechanical properties of gels causing rough reproducibility of mechanical experiments. In the present paper, the simple bulk polymerization is proposed as another candidate to create a standard GEM. The key point of the present work is to use the liquid type of highly reactive monomer, which plays the role of solvent in preparation, and thus we do not have to consider both the ratio concentrations of the monomer and the accelerator to the solvent in preparation. In this case we can focus only on the ratio concentration of the crosslinker to the monomer. This ratio concentration is directly related to the contour length of the polymer chain between the crosslinking points. We have found that the mechanical properties of the dry-synthesized GEM depend hardly on the ratio concentration of the initiator to the monomer, but mainly on that of the crosslinker. The Young's modulus is simply, well described as a power function of the crosslinker concentration. We hope this dry-synthesized GEM will be useful as another novel standard sample for mechanical engineering research.

DOI： 10.1299/jmmp.7.455

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

In this paper, aggregation/dispersion behaviors of particle clusters in a non-uniform shear flow have been numerically analyzed using a thixotropy model for estimating local cluster size distributions. The effects of the viscosity of the dispersion media, the solid volume fraction and the Reynolds number on the cluster size distribution in a two-dimensional flow between parallel plates were investigated in order to find the primary factor determining the cluster size distributions. The viscosity of the dispersed media, the solid fraction and the Reynolds number were changed from 195 to 1950 Pa.s, from 0.10 to 0.25 and from 0.1 to 1.0, respectively. From the results, it is found for each case that large clusters are observed at the central area of the channel, but it becomes smaller near the wall where high shear is added. The cluster size near the wall is dominated by the shear stress. On the other hand, it is found that the cross-sectional averaged cluster size depends on the bulk velocity under the present conditions. As the cluster size near the wall can be correlated rather well with the bulk velocity, it is concluded that the bulk velocity is a convenient and useful factor for the dispersion/aggregation behaviors of fine particles under the present conditions.

DOI： 10.1252/jcej.13we016

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

A model estimating local particle dispersion/aggregation behaviors in a suspension has been developed for a nonuniform shear flow. In this model, the size distributions of particle clusters were calculated with taking a balance of Brownian and shear coagulationsand shear breakup. A numerical simulation was performed for a two-dimensional backward-step flow as a non-uniform shear flow. A flow experiment using a micro-channel with a rib was also conducted for the verification of the present numerical analysis. The solid volume fraction of the suspension was set at 0.01 and the step height Reynolds number was keptconstant at 1.5×10-4 both for numerical and for experimental studies. The numerical results obtained in this study were rather reasonable compared with the experimental data. From this, it was found that the present numerical model is promising for estimating particle dispersion/aggregation in a non-uniform shear flow. © 2013 The Society of Rheology, Japan.

DOI： 10.1678/rheology.41.75

Scopus

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Polymer solution shows complex behaviors, which are merits and demerits in industries. For a molding process, a fiber spinning process and a turbulent drag reduction system, concentrated or dilute polymer solutions are used. In these processes, characteristics of extensional viscosity should be important. For example, increments of extensional viscosities due to polymers are considered as one of the reasons for the drag reduction occurrence. In this study, we propose a simple technique to measure the extensional viscosity of Newtonian and non-Newtonian fluids in abrupt contraction flows. The abrupt contraction flow was realized by connecting a syringe and a thin glass tube under a polarizing microscope. The syringe was filled with Newtonian and non-Newtonian fluids, and a syringe driver control to push the fluids out. The force to push the syringe was measured by a load cell to calculate the pressure added to the flow. Extensional viscosity was calculated by considering the pressure losses in the abrupt contraction flows. Water was measured as a Newtonian fluid, and polymer solution was measured as a non-Newtonian fluid. Extensional viscosity of the polymer solution measured in this study qualitatively shows the reasonable characteristics. © 2013 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaib.79.1264

Scopus

J-GLOBAL

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)  

Shape memory gels (SMG) are one kind of functional materials that can be deformed plastically and fixed the deformed shape at lower temperature. At higher temperature, SMG can return their original shape. A novel transparent SMG (SA-DMAAm gels) was developed from crystalline monomer stearyl acrylate (SA) and amorphous monomer N,N-dimethylacrylamide (DMAAm). We had succeeded in improving its mechanical properties. In this work, the aim is to develop conductive SMG by adding carbon black into SA-DMAAm gels. The molar ratio of SA to DMAAm was 1:3, and the weight ratio of carbon black to DMAAm was 1/100. The shape of prepared conductive SMG (SA-DMAAm/Carbon gels) is possibly controlled by Joule heat. This feature has quite promising applications in the field of new devices. The mechanical, shape-memory and conductive properties, as well as crystal structure of SA-DMAAm/Carbon gels were characterized. © 2013 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaia.79.512

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Gels have unique properties such as low frictional properties, permeability and biocompatibility due to their high water content. When the gels are developed as industrial materials, we need to establish a method of quantitative analysis derived from the internal structure and mechanical properties of these gels. In this study, the internal structure of the dry-synthesis gels were precisely examined experimentally by the scattering microscopic light scattering and theoretically by the tensile test. By comparing the two quantities, the dense network structure makes the mechanical properties of gels smaller than theoretical estimation. Based on our findings, the strength of the gels can be controlled and expected.

DOI： 10.1299/jmmp.7.224

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Medical treatments in emergency should be simple and quick. Although bandages and plaster are commonly used to wrap and fix external injuries, these treatments are too simple to treat the injuries effectively. Smart materials could possibly add multiple beneficial functions to the bandages and plaster, such as cooling, shape memory, transparence, and recycling. Here, we propose novel high-strength shape-memory gels as smart medical materials. The gels are composed of several polymers of a unique structure, where the crosslinking forms covalent bonds solely between different polymers. We named this structure inter-crosslinking network (ICN), with gels becoming tough while having a high water content. The ICN gels achieve a high ductility, i.e., over 740% strain in tensile tests. The ICN gels retain their original shapes at the state of preparation, show plastic deformation at room temperature, and quickly recover to their original shape by heating only.

DOI： 10.1246/cl.2012.1029

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A novel push button is developed using shape-memory gels (SMGs). The Young's modulus of SMGs changes dramatically with temperature. This modulus change is utilized to control the input-acceptable and input-not-acceptable states of the button. We believe the mechanism of this button could be used to develop new devices, especially for the visually impaired.

DOI： 10.1246/cl.2012.1047

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

The frictional behavior of the two kinds of high-strength gels, which were double network (DN) gels and shape memory gels (SMG), was studied. By using a commercial measuring instrument with an empirical fitting function, the coefficient of dynamical friction for the DN gels and the SMG was determined. The velocity dependence of the coefficient looked roughly similar for both the DN gels and the SMG, however the details of the dependence were different. The coefficient of the DN gels was smaller than that of the SMGs. The coefficient decreased as the normal force increased. This normal force dependence was observed for the DN gels previously, however for the first time for the SMGs. The differences of both the velocity and normal-force dependences between the DN gels and SMG were discussed in relation to their mechanical properties determined in the previous studies. It implied that the difference of the dependences was possibly related to the different softness of the gels.

DOI： 10.1299/jmmp.7.228

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Publishing type：Research paper (international conference proceedings)  

researchmap

Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

Most of lenses embedded in optical devices used today are as hard as a glass and not deformable. Therefore, it is needed to move the positions of the lenses in focusing and zooming. Actual optical devices sometimes become complex and large. Here we improve Double Network gel lens and newly propose deformable lens system by virtue of high-strength, transparent and transformable hydrogels. Shape-Memory gels are applied to the deformable lens systems. The focal length of DN gel lens was controlled by the degree of swelling of gels. In the deformable lens systems a water layer is sandwiched between two gel sheets to compose a variable focus lens. By changing the pressure of the water layer, the radius of convex curvature of the gel sheet surface can be controlled, and the focal length of the lens can be adjusted. Further, the SMG lens can memorize its shape, so that the focal length can be fixed. The DNG and SMG lenses bring new possibilities to develop actuated gel lenses, which are simple and small, but highly functionalized. © 2012 The Surface Science Society of Japan (http://www.sssj.org/ejssnt).

DOI： 10.1380/ejssnt.2012.243

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Gels have low frictional properties, permeability and biocompatibility due to high water content. In the last decade, several high-strength gels have been developed, which are promising for extending the application of gels as industrial materials. In this study, ultrahigh ductile gels are proposed by developing Inter Cross-linking Network (ICN), which is the novel internal structure of gels. The ICN gels can achieve more than 67.9% increase in the ductility in comparison with normal poly(<I>N</I>,<I>N</I>-dimethylacrylamide) gels, only by adding a little amount of fiber, hydroxypropyl cellulose, which is known as lyotropic crystalline polymer, while containing 97wt% water.

DOI： 10.1299/jmmp.6.169

J-GLOBAL

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)  

After 2001, several methods have been devised to improve the mechanical strength of gels extraordinarily. It was a trigger to use gels as a new industrial materials, since gels had been considered difficult for industrial materials because of their weakness. The purpose of this study is to create novel composite materials, which realizes the further high strength of gels by adding fiber to the gels. We evaluated the mechanical properties of the gels, containing a very small amount of the fiber, in order to quantify how the fiber works for enhancement of the gels. It is found that to improve the adhesion between fiber and the gel matrix is important for increasing the mechanical strength of the newly proposed gels. Since there are many kinds of gels and fibers, it becomes possible to achieve a dramatic enhancement of the strength if we find an appropriate combination for rigid adhesion. © 2012 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaia.78.1120

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

Gels have unique properties such as low frictional properties, permeability and biocompatibility due to their high water content. In the last decade, several high-strength gels have been developed, which are promising for extending the application of gels as industrial materials. Previously we proposed novel ultrahigh ductile gels by defining inter-crosslinking network (ICN) structure. In this study, the mechanical properties of ICN gel was studied by experiments and theoretical estimations, and the mesh size of the internal network structure were determined. It is found that the Young's modulus of ICN gels calculated by experiments well matches with the theoretical estimations. The appropriate ICN gels achieves more than 61% increase in the ductility in comparison with normal poly(N
N-dimethylacrylamide) (PDMAAm) gels, by introducing the ICN structure. For the ICN gels, the density of chains calculated from the mesh-size is well consistent with the other densities calculated from the modulus and the water content, in comparison with the PDMAAm gels. © 2012 The Surface Science Society of Japan.

DOI： 10.1380/ejssnt.2012.346

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

Novel high-strength gels, named double network gels (DN gels), show a smart response to altering external electric field. It was reported that a plate shape of the DN gel bends toward a positive electrode direction when a static (DC) electric field is applied. Based on this previous result, it has been tried to develop a novel soft and wet actuator, which will be used as an automatically bulging button for cellar phones, or similar small devices. First, a bending experiment of a hung plate-shape DN gel was done, and its electric field response was confirmed. Second, the response of a lying plate-shape DN gels was confirmed in order to check the bulging phenomena. The edge of three plate-shape gels that was arranged radially on a plane surface was lifted 2mm by applying DC 8V. This system is a first step to make a gels button. However the critical problem is that electrolysis occurs simultaneously under electric field. Then, the water sweep out from gels, and gels is shrinking; They cause the separation between aluminum foil working as electrode and gels. That is why, a flexible electrode should be made by gels completely attached to the gels. As a third step, a push button is tried to make by a shape memory gels (SMG). The Young's modulus of the SMG is dramatically changed by temperature. This change in the modulus is applied to control the input-acceptable state and input-not-acceptable states of the button. A novel push button is proposed as a trial, and its user-friendliness is checked by changing the size of the button. The button is deformed by pushing and is back to original shape due to the property of shape memory. We believe the mechanism of this button will be applied to develop new devices especially for visually impaired persons.

DOI： 10.1117/12.915091

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

Sensitive deformation of polymer gel actuator induced by various stimuli has been intensively investigated. The utilization of light however will significantly broaden their applications. Here we show that photo-responsive gels prepared from rigid poly(amide acid) chains having azobenzene moieties in main chains can undergo a macroscopic deformation induced by photo-isomerization. A rod-shape gel can sharply and swiftly bend by blue laser irradiation and reversibly straighten when exposed to visible light. By using a scanning microscopic light scattering, the optimal preparing condition of the gels was determined and the reversible change in mesh-size between 2.1 nm and 0.83 nm was observed.

DOI： 10.1117/12.915184

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

Medical treatment for injuries should be easy and quick in many accidents. Plasters or bandages are frequently used to wrap and fix injured parts. If plasters or bandages have additional smart functions, such as cooling, removability and repeatability, they will be much more useful and effective. Here we propose innovative biocompatible materials, that is, nontoxic high-strength shape-memory gels as novel smart medical materials. These smart gels were prepared from two monomers (DMAAm and SA), a polymer (HPC), and an inter-crosslinking agent (Karenz-MOI). In the synthesis of the gels, 1) a shape-memory copolymer network is made from the DMAAm and the SA, and 2) the copolymer and the HPC are crosslinked by the Karenz-MOI. Thus the crosslinking points are connected only between the different polymers. This is our original technique of developing a new network structure of gels, named Inter-Crosslinking Network (ICN). The ICN gels achieve high ductility, going up to 700% strain in tensile tests, while the ICN gels contain about 44% water. Moreover the SA has temperature dependence due to its crystallization properties; thus the ICN gels obtain shape memory properties and are named ICN-SMG. While the Young's modulus of the ICN-SMG is large below their crystallization temperature and the gels behave like plastic materials, the modulus becomes smaller above the temperature and the gels turn back to their original shape.

DOI： 10.1117/12.915090

Web of Science

J-GLOBAL

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

In the human body, full of biological non-Newtonian fluids exist. For example, synovial fluids exist in our joints, which contain full of biopolymers, such as hyaluronan and mucin. It is thought that these polymers play critical roles on the smooth motion of the joint. Indeed, luck of biopolymers in synovial fluid cause joint pain. Here we study the effects of polymer in thin liquid layer by using an original experimental method called Film Interference Flow Imaging (FIFI). A vertically flowing soap film containing polymers is made as two-dimensional flow to observe turbulence. The thickness of water layer is about 4 mu m sandwiched between surfactant mono-layers. The interference pattern of the soap film is linearly related to the flow velocity in the water layer through the change in the thickness of the film. Thus the flow velocity is possibly analyzed by the single image analysis of the interference pattern, that is, FIFI. The grid turbulence was made in the flowing soap films containing the long flexible polymer polyethyleneoxide (PEO, M-w=3.5x10(6)), and rigid polymer hydroxypropyl cellulose ( HPC, M-w &gt; 1.0 x10(6)). The decaying process of the turbulence is affected by PEO and HPC at several concentrations. The effects of PEO are sharply seen even at low concentrations, while the effects of HPC are gradually occurred at much higher concentration compared to the PEO. It is assumed that such a difference between PEO and HPC is due to the polymer stretching or polymer orientation under turbulence, which is observed and analyzed by FIFI. We believe the FIFI will be applied in the future to examine biological fluids such as synovial fluids quickly and quantitatively.

DOI： 10.1117/12.915171

Web of Science

J-GLOBAL

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

The addition of very small amounts of flexible polymer to a flow reduces drag in turbulent flow by almost 60% at the maximum. The phenomena has been tried to explain by velocity profile near the wall. Thus, shear strain and shear viscosity gathered much attentions. However, viscoelasticity of polymers that is extensional viscosity should also important to affect fluids. It is said that the extensional viscosity is increased by causing polymer entangled, however, the extensional viscosity should be also increased when the polymer is stretched. In this study, flexible polymer that is easily stretched under strain and naturally stretched rigid polymer are added to the fluids to observe how it effects on turbulent dynamics. For the visualization and single-image analysis of turbulence, our original method - Film Interference Flow Imaging method - is used. Inner structure of sample solution is analyzed by Scanning Microscopic Light Scattering to investigate how polymers expand in fluids. Here, it is assumed that sudden stretch of the flexible polymer in flow cause sudden increase of extensional viscosity, and gradual orientation of the rigid polymer cause gradual increase, which is related to the turbulent drag reduction. Such a fluids control can work not only to improve energy efficiency in industries but also to treat micro fluids in medical area. © 2012 The Surface Science Society of Japan.

DOI： 10.1380/ejssnt.2012.335

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The contraction process of living Vorticella sp. in polymer solutions with various viscosities has been investigated by image processing using a high-speed video camera. The viscosity of the external fluid ranges from 1 to 5mPa{dot operator}s for different polymer additives such as hydroxy-propyl cellulose, polyethylene oxide, and Ficoll. The temporal change in the contraction length of Vorticella sp. in various macromolecular solutions is fitted well by a stretched exponential function based on the nucleation and growth model. The maximum speed of the contractile process monotonically decreases with an increase in the external viscosity, in accordance with power law behavior. The index values approximate to 0.5 and this suggests that the viscous energy dissipated by the contraction of Vorticella sp. is constant in a macromolecular environment. © 2012 The Biophysical Society Of Japan.

DOI： 10.2142/biophysics.8.11

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The contraction process of living Vorticella sp. has been investigated by image processing using a high-speed video camera. In order to express the temporal change in the stalk length resulting from the contraction, a damped spring model and a nucleation and growth model are applied. A double exponential is deduced from a conventional damped spring model, while a stretched exponential is newly proposed from a nucleation and growth model. The stretched exponential function is more suitable for the curve fitting and suggests a more particular contraction mechanism in which the contraction of the stalk begins near the cell body and spreads downwards along the stalk. The index value of the stretched exponential is evaluated in the range from 1 to 2 in accordance with the model in which the contraction undergoes through nucleation and growth in a one-dimensional space. © 2012 The Biophysical Society Of Japan.

DOI： 10.2142/biophysics.8.1

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Double network (DN) gels are anomalously robust but soft and wet materials, whose maximum stress in compression reaches 30MPa and surface friction coefficient reaches 0.001 simultaneously. The DN gels also have shock absorbency, permeability, and biocompatibility. Thus it is expected that the DN gels will be applied to artificial joints, artificial cartilages, and artificial blood vessels. In this study we focused on both high transparency and large transformation of the DN gels, and we tried to develop novel optical devices. Our purpose is to apply it to a deformable lens system. Indeed, we succeed to make an artificial gel lens, which is nontoxic and have biocompatibility. The value of strain of the gel lens can achieve more than 2, and Young's moduli of our two kinds of DN gels show 0.45MPa and 0.46×10<SUP>-1</SUP>MPa, which is enough higher than human lens. We will realize further miniaturization and simplification of various optical products containing the gel lens.

DOI： 10.1299/jmmp.5.1015

J-GLOBAL

researchmap

Authorship：Lead author,　Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Thin liquid layer exists between bone and bone in joint of human body, and also, thin tear film covers cornea. These thin liquid layers contain biopolymer such as hyaluronic acid and mucin. These thin liquids make it possible that smooth movement of the joints and smooth blinks. In this research, effects of polymer in thin liquid layer are studied by using flowing soap films. Soap films consist of about 4 thickness water layer inside and surfactant mono-layer in the surface. Interference patterns of the soap films are affected by the thickness of the water layer. Thus the interference pattern reflects the behavior of the water layer. In this study, turbulence was made in flowing soap films, the effects of long flexible polymer Polyethylene oxide (PEO, <I>M</I><SUB>w</SUB>=4x10<SUP>6</SUP>) to the turbulence was observed by the interference pattern. This technique is proposed as <I>Film Interference Flow Imaging method</I> (FIFI). Thickness and velocity information of the turbulence were observed by FIFI. Inner structure of the soap solution containing PEO was observed by <I>Scanning Microscopic Light Scattering</I> (SMILS) which is a light scattering system specialized for analyzing microscopic structures. For some applications, investigations of the polymer effects in thin liquid layer are useful for the development of polymer drag for joint pain or dry eyes.

DOI： 10.1299/jmmp.5.838

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Double network (DN) gel is one of high-strength strongest gels in the world. Its maximum stress in compression is over 30MPa, and its surface frictional coefficient is 0.0001 at suitable conditions. Thus the DN gels realize both anomalously high strength and extremely low friction at the same time. The DN gels will be possibly used as medical materials. Here a system, which can make 3-dimensional optical forming of the DN gels by using ultraviolet laser, was proposed in order to make an artificial blood vessel experimentally. A suitable forming scheme is found, and the mechanical strength of the vessel is evaluated. The artificial vessels formed by DN gels are promising, since this material can penetrate water, oxygen, etc. Thus, the vessel can work more naturally in human bodies.

DOI： 10.1299/kikaia.77.1002

researchmap

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Shape-memory gels, composed of both crystalline part and amorphous gel part as composite, can be used to develop novel self-repairing materials solving environmental problems in recent days. In this study, the shape-memory gels are reinforced by adding hydroxypropyl cellulose (HPC) as a liquid crystalline polymer, in order to improve the strength of the ordered structure in the crystalline part or to improve the toughness of the elastic matrix of the amorphous part. It is found that the maximum stress of the HPC-reinforced shape-memory gels is increased with low molecular weight of HPC. On the other hand, the maximum strain is increased with high molecular weight HPC especially. It implies that the effects of HPC depend on the molecular weight, that is, low molecular weight HPC strengthens the crystalline domain, while high molecular HPC reinforces the amorphous gel matrix. Also, X-ray scattering showed that the HPC enhances the slip of lamellar structure in the crystalline domain during self-repairing process.

DOI： 10.1299/kikaia.77.764

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The formation process of onion structure in a quaternary mixture, which consists of water, NaCl, octanol and sodium dodecyl sulfate, has been investigated by two-dimensional light scattering under oscillatory shear flow. In our experiment, we investigate the size evolution of onion structure which is estimated by light scattering data with a nonlinear least-squares curve fitting method. The time evolution of onion size is in good agreement with a stretched exponential function. The effect of oscillatory shear flow on formation process of onions is briefly discussed by considering the physical meaning of fitting parameters based on the integral transformation method. (c) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2009.05.025

Web of Science

J-GLOBAL

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Biophysical Society of Japan General Incorporated Association  

DOI： 10.2142/biophys.49.S175_5

researchmap

Publishing type：Research paper (international conference proceedings)  

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

DOI： 10.3811/jjmf.2020.T005

researchmap

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

researchmap

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

researchmap

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：近畿冷凍空調工業会  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

researchmap

Language：Japanese   Publisher：日本冷凍空調学会  

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Control of aggregation/dispersion behavior of fine particles in a suspension is important to improve characteristics of complex materials. The dispersion behavior of fine particles in a suspension was observed and analyzed in a flow across sudden contraction in a microchannel. The dispersed particle and media of the suspension were polystyrene (diameter: 3:5 μm) and 27:0 wt% aqueous glycerol solution. The volume fraction was 0.02. The suspension was introduced to the microchannel using syringe pump. The velocity and dispersion behavior of fine particles of the suspension were determined in the PIV and image analysis. As a result, the velocity profile was fully developed at x/H = 0:23. The profile of the mean number of particles in a cluster at x/H = 0:24 was equal to the profile at upper stream. At x/H = 0:74, the mean cluster size was smaller than that at x/H = 0:24 It indicates a difference in the entrance region of the velocity field and aggregation/dispersion characteristics.

CiNii Books

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Instability characteristics observed in a micro-cavity swept by a visco-elastic fluid has been investigated. Surfactant solution used as a viscoelastic fluid was inserted in a micro-cavity whose length, depth and wide low path were set constant at 1, 0.2 and 0.4 mm, respectively. The time variation of the tonguing motion of the separation bubble formed in the downstream region in the cavity was measured when the Reynolds number defined with water viscosity, cavity depth and the mean velocity in a narrow flow path was change in three steps: 1, 5 and 20. From the results, it was found that the fluctuation time scale is from 1.9 to 4.5 s, which is located between the middle and longest relaxation times. It was also found that the time scale does not depend on the Reynolds number.

CiNii Books

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

CiNii Books

researchmap

Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

researchmap

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.10

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.10

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (invited, special)  

researchmap

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.7 - 2023.8

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.5

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2023.5

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2022.3

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2022.3

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2022.3

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2022.3

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (invited, special)  

researchmap

Event date： 2021.12

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.12

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.12

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.12

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.11 - 2021.12

Language：English  

researchmap

Event date： 2021.11

Language：Japanese  

researchmap

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.10

Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

researchmap

Event date： 2021.10

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.10

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2021.10

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.10

Language：English   Presentation type：Poster presentation  

researchmap

Event date： 2021.10

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.10

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (invited, special)  

researchmap

Event date： 2021.9

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.5

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.5

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.5

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2021.3

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2021.3

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.2

Language：English   Presentation type：Oral presentation (invited, special)  

researchmap

Event date： 2021.2

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.2

Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

researchmap