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

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

Weak turbulence has been investigated in nonlinear-nonequilibrium physics to understand universal characteristics near the transition point of ordered and disordered states. Here the one-dimensional Nikolaevskii turbulence, which is a mathematical model of weak turbulence, is studied theoretically. We calculate the velocity field of the Nikolaevskii turbulence assuming a convective structure and carry out tagged-particle simulations in the flow to clarify the Nikolaevskii turbulence from the Lagrangian description. The tagged particle diffuses in the disturbed flow and the diffusion is superdiffusive in an intermediate timescale between ballistic and normal-diffusive scale. The diffusion of the slow structure is characterized by the power law for the control parameter near the transition point of the Nikolaevskii turbulence, suggesting that the diffusive characteristics of the slow structure remain scale invariant. We propose a simplified model, named two-scale Brownian motion, which reveals a hierarchy in the Nikolaevskii turbulence.

DOI： 10.1103/PhysRevE.101.022202

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

We report study on the effect of Br and CH₃ inductive groups on the loading capacity of carboxylate-based hydrogel adsorbent. Synthesized sodium acrylate (NaAc) and 2-Bromoacrylic acid (BrAc) copolymer hydrogels for metal ion capture were characterized using FTIR, UV–Vis, ¹³C NMR, and DSC methods for structural and functional properties. Both FTIR and UV–Vis spectra indicated formation of a charge transfer complex between Br, CH₃ groups and the carbonyl (C═O) group whereas solid-state NMR evidenced Br group appearance as an appendage on hydrogel backbone. By incorporating Br group on the hydrogel matrix and consequently exploiting the high electronegativity potential and inductive effect chemistry of this group, there was a significant increase in dissociation of H⁺ ions and hence higher loading capacity of carboxylate group. This facilitated higher ion exchange ability, resulting in up to 4 times increase in adsorption capacity during adsorption from multi-element metal ion competitive solution. Separately, when applied on single ion non-competitive solution, its adsorption capacity on vanadium increased three-fold from 119 mg/g to 373 mg/g due to the effect of Br group. However, the CH₃ had a negating effect instead lowering the adsorption capacity (below 119 mg/g); while also caused lower swelling ratio of carboxylate-functionalized hydrogel adsorbents.

DOI： 10.1016/j.polymertesting.2019.106117

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

The study attempted solving hazardous heavy-metal problems by creating a new eco-friendly functional hydrogel adsorbent (CSB-hydrogel). By utilizing γ-irradiation induced grafting and co-polymerization, the CSB-hydrogels were synthesized from a main bio-polymer {Sodium Carboxymethyl Cellulose (CMC)} and two active vinyl monomers {Sodium Styrene Sulfonate (SSS) and Bis[2-(Methacryloyloxy)Ethyl] Phosphate (BMEP)}. As well as the compression moduli, the CSB-hydrogels showed significant difference in the swelling capacities with the variety of BMEP-amounts. The author then examined the CSB-hydrogels’ multi-metal-ion adsorption capacities by performing the ion-capturing experiments with a varying species mixture solution and by utilizing ICP-MS analysis technique. The CSB-hydrogels demonstrated their highly-efficient recovery functionalities for most of the metal ions in the solution; especially, higher than 70% for nickel. Moreover, the CSB-hydrogels showed sufficient performance after 4-time repetitive adsorption-desorption treatments. With the high heavy-metal capturing-efficiency and the re-usability, the CSB-hydrogels were revealed to have a high potential as a new eco-friendly environment-purifying material.

DOI： 10.1016/j.polymer.2019.121772

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

An electroconvection (EC) in liquid crystal is used in the experimental study of turbulent transport. The transport characteristics in EC turbulence were investigated with a planer cell, and the diffusive property of turbulent transport was identified, which is identical to that of normal viscus fluid described by Navier–Stokes equation. Experimental research on turbulent transport using EC in a rotating spherical shell is proposed. A demonstration of the production of EC turbulence in a rotating spherical shell was carried out, where the radial gravity was replaced by electric field.

DOI： 10.1016/j.hedp.2019.03.006

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

Hybrid hydrogels were prepared by blending Carboxymethyl chitosan (CMCts), Carboxymethyl cellulose (CMC) with Sodium sulfonate styrene (SSS) by 60-kGy gamma rays. The prepared hydrogels were utilized as silver-ion (Ag) sorbent under non- and competitive cases. Batch adsorption experiments were conducted in functional conditions including contact time, ratios of (CMC:CMCts) and SSS, pH value, temperature and adsorbent weight. Equilibrium contact time of 10 h. was obtained by the adsorption material. The optimal 4:2 ratio of (CMC:CMCts):SSS showed the Ag highest adsorption efficiency. The maximum percentage of Ag⁺ removal was achieved at the pH 5. The temperature effect on the adsorption ability of hybrid hydrogel indicated the Ag adsorption process was endothermic and spontaneous. The Langmuir isotherm model fitted Ag adsorption data well, assuming a monolayer adsorption with predicted maximum adsorption capacity of 451.74 × 10⁻³ mg. g^–1. From the kinetic data, the process of Ag adsorption had higher agreement with the pseudo-2nd order model, predicting the amount of Ag⁺ uptake at different contact time intervals and at equilibrium.

DOI： 10.1016/j.jhazmat.2018.11.008

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

The present research is focused on the selective adsorption of trivalent metal ions from multielement solution by using functional hydrogel. The hydrogels were synthesized from the aqueous blend of Pectin, Acrylamide (AAm) and 2-Acrylamido-2-methyl-1-propanesulfonic acid (AMPS) by applying gamma radiation. The results of gel fraction and equilibrium swelling optimized 1:2:3 ratio of raw materials (pectin, AAm, and AMPS) and 2 kGy radiation dose for the preparation of hydrogels. The functional groups of the hydrogel were confirmed by Fourier transform infrared (FTIR) spectroscopy. The thermal properties were studied by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) was used to analyze the surface morphology of hydrogels before and after metal adsorption. Hydrogels were applied to selective adsorption of five elements (Al, Cr, Fe, Ga, and In) from the multielement solution as well as adsorption from the manually prepared solution of five elements. The effect of pH on the adsorption capacity of hydrogel was examined. The adsorption data was used to study the adsorption isotherm models where the Freundlich adsorption isotherm model was found to be well fitted compared to the Langmuir adsorption isotherm model. From the Freundlich isotherm model, the maximum adsorption capacities of Al, Cr, Fe, Ga and In were found to be 11.34, 11.52, 11.92, 11.57 and 17.73 mg/g of gel respectively. Desorption efficiency was found to be about 80%. The research results suggest that the hydrogel can effectively be used for the recovery of above mentioned trivalent metal ions.

DOI： 10.1016/j.jece.2018.102844

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

The properties of chaotic advection arising from defect turbulence, that is, weak turbulence in the electroconvection of nematic liquid crystals, were experimentally investigated. Defect turbulence is a phenomenon in which fluctuations of convective rolls arise and are globally disturbed while maintaining convective rolls locally. The time-dependent diffusion coefficient, as measured from the motion of a tagged particle driven by the turbulence, was used to clarify the dependence of the type of diffusion on coarse-graining time. The results showed that, as coarse-graining time increases, the type of diffusion changes from superdiffusion ? subdiffusion ? normal diffusion. The change in diffusive properties over the observed timescale reflects the coexistence of local order and global disorder in the defect turbulence.

DOI： 10.3390/fluids3040099

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

This article exploits a new approach for synthesis of polysaccharide-based grafted sodium styrene sulfonate (SSS) super absorbent hydrogels (SAHs) in aqueous solution by γ-radiation under ambient conditions. Important optimal conditions for preparation of hydrogels with the best swelling ratio, such as gamma irradiation dose and the ratio of feed composition have been discussed. Characterization techniques such as the SEM/EDS, FTIR and DSC were used in describing the newly prepared hydrogels. The FTIR gave characteristic peaks for -SO
₃
Na group at 1042 and 988 cm
⁻¹
, showing successful grafting of SSS onto the polysaccharide base material. The dependence of swelling behaviors in various pH solutions and salts solutions were investigated in detail. The prepared hybrid hydrogel showed most optimum swelling capacity at neutral pH whereas equilibrium swelling of SAHs was achieved within 5 h. The swelling of SAHs influenced obviously to metal ion removal percentage in solution.

DOI： 10.1016/j.envpol.2018.07.129

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

Synthesis of hydrogel adsorbent for high selectivity and strong chelate removal of transition metals Cr, Cu and Ni was accomplished via sol-gel method using ligand monomers maleic acid and (2, 2′ ethylenedioxy) bis (ethylamine) reagent. We obtained a 14-membered macrocyclic functional unit called poly (1, 4-dioxa-7, 12-diazacyclotetradecane-8, 11-dione) as the main active sites for metal adsorption. The new adsorbent's cross-linked polymer chains was clearly visualized using SEM spectroscopy; whereas the FTIR, ¹³C NMR and EDX techniques demonstrated its structural and functional groups. With an improved chelating power, this macrocyclic hydrogel was able to ignore non-target substrates, instead showing high specificity for only Cu, Cr and Ni from both single and multi-ion competitive aqueous solutions, in the order Cr > Cu > Ni. Pseudo-second order kinetic model aptly described the adsorption process, revealing chemisorption as the main mechanism which proceeded based on the host-guest chelation principle of metal ions onto the gel's macrocyclic active sites. Thus a high performance, high selectivity adsorbent system was achieved using active sites bearing substrate recognition and isolation properties.

DOI： 10.1016/j.reactfunctpolym.2018.06.006

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

Macrocyclic functional hydrogels incorporating new poly cyclic active sites (1,4,7-trioxacycloundecane-8,11-dione) within their entire network, have been synthesized. Using the high-dilution coupling of the bi-functional monomers maleic acid and bis(chloroethyl)ether in a sol-gel chemistry synthesis, 11-membered chelate rings infused with three oxygen donor atoms were created and characterized, and their structures confirmed using Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic analyses. The macrocyclic gel, designed for selective host-guest adsorption and complexation of metal substrates, was initially tested against an aqueous set of 14 metal competitive solutions, where it demonstrated exclusive selectivity for Bi³⁺ _aq, with the other metals exhibiting zero adsorption. Further analysis using binary and single ion Bi³⁺-containing solutions showed a near-complete removal of Bi³⁺ using this polycyclic hydrogel, with 98% extraction efficiency and q = 9.80 mg/g. These results clearly confirm that the 1,4,7-trioxacycloundecane-8,11-dione cyclic sites are most suitable for high selectivity and capture of Bi. The metal substrates were entrapped within the 1,4,7-trioxacycloundecane-8,11-dione cyclic sites. Evidently, by exploiting the host-guest complexation chemistry of macrocycles, we were able to design hydrogel adsorbents whose networks were comprised entirely of macrocyclic active groups for possible purification works of copper involving bismuth impurities, and/or for efficient selective uptake and recovery of bismuth trace ions existing in highly competitive environments such as sea water.

DOI： 10.3390/polym10060662

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

The objective of the work is to synthesize pectin-N, N-Dimethylacrylamide (DMAA) hydrogel by gamma radiation without using any initiators and cross-linking agents. Effect of radiation doses on gel fraction and equilibrium swelling as a function of pH were studied, and 5 kGy radiation dose was found to be the optimum dose for hydrogel synthesis. The grafting /crosslinking was investigated by Fourier transform infrared spectroscopy. Thermal properties and surface morphology were studied by differential scanning calorimetry and scanning electron microscopy. To study the drug release kinetics, 5-fluorouracil was loaded into the hydrogel and in vitro release was carried out in simulated gastric and intestinal fluid. The release profile of drug showed that more than 90% of the loaded drugs were released after 4 hours at both gastric fluid and intestinal fluid pH. Drug release data was fitted into zero order, Higuchi and Korsmeyer-Peppas kinetic models. Higuchi model was found to be the best fitted and release exponent ‘n’ value of Korsmeyer-Peppas model indicated the non-Fickian transport.

DOI： 10.1080/10601325.2018.1442177

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

We present a method of synthesizing macrocyclic hydrogel systems using sol-gel polymerization and for high selectivity adsorption works. The hydrogel was fabricated using maleic acid and ethylene diamine ligand and characterized using FTIR, Raman, SEM/EDX, ¹³C NMR and SAXS techniques. It was revealed that 1, 4-diazocane-5, 8-dione were the principal active sites of this adsorbent. These macrocyclic sites provided defined zones which limited capture and chelation of transition metal ions such that from single ion solutions, only ion substrates of between 1.23 and 1.29 Å ionic size were mainly adsorbed; whereas in case of metal-metal competitive solutions, then only 1.29 Å sized substrates would be adsorbed. This adsorption specificity required that aqua metals of these sizes be of octahedral configurations for more optimum host-gest chelation with the gel active sites. Since Fe_(aq) effectively met these criteria, the gel adsorbent displayed outstanding specificity for Fe_(aq) adsorption from different levels of competitive environments. Present adsorbent showed that macrocyclic chelate sites can be infused directly into the hydrogel network without any grafting, and facilitates a shape-based, size-limited adsorption. This hydrogel is a promising candidate for applications in heavy metal pollution remediation, drug development and fuel cell catalysts, where high specificity adsorptions are desirable.

DOI： 10.1016/j.reactfunctpolym.2018.02.003

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

Pectin-[(3-acrylamidopropyl) trimethylammonium chloride-co-acrylic acid] hydrogel has been prepared from the aqueous blend solution of pectin, (3-acrylamidopropyl) trimethylammonium chloride (APTAC), and acrylic acid (AAc) by applying gamma radiation of different doses (1–25 kGy) from ⁶⁰Co gamma source. The hydrogels were characterized by equilibrium swelling, Fourier transform infrared, differential scanning calorimetry, and scanning electron microscopy. The hydrogels were used in multielement adsorption and it was found that pectin-(APTAC-co-AAc) gel is highly selective toward silver (I) ion among 27 metal ions. The data obtained from equilibrium adsorption studies were fitted in Langmuir and Freundlich adsorption isotherm models and model parameters evaluated. The maximum adsorption capacity of pectin-(APTAC-co-AAc) gel was found to be 67.6413 mg/g of dry gel at sample volume of 25 mL. The kinetic data were tested using pseudo-first order and pseudo-second order kinetic models and different adsorption diffusion models such as film diffusion and intra-particle diffusivity model. Thiourea solution was used for desorption of adsorbed metal ions from the hydrogel.

DOI： 10.1002/app.45906

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

Diffusion resulting from turbulence corresponding to dynamic scattering mode 1 (DSM1) of electroconvection was studied in experiments on homeotropically aligned systems of nematic liquid crystals. In such systems, electroconvection displays peculiar nonlinear phenomena arising from the interaction between its convection and the nematic director yielding Nambu–Goldstone modes. From an analogy with Brownian motion, the motion of tagged particles driven by the turbulence was analyzed using the time-dependent coefficient of diffusion, defined as the mean-square displacement divided by time. The results indicate that sub-diffusion occurs in a certain time range, suggesting that turbulence causes particles to rebound. Detailed observations of turbulence structures revealed that rebounding is induced by characteristic linear structures of the nematic director caused by turbulence. This sub-diffusion arising from the interaction between the nematic director and turbulence is specific to nematic liquid crystals.

DOI： 10.7566/JPSJ.87.014401

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

Sodium Carboxymethyl Cellulose (CMC[sbnd]Na)/Sodium Styrene Sulfonate (SSS) hydrogels with grafted and crosslinked polymeric networks were prepared by γ-radiation at atmosphere condition. The obtained hydrogels were characterized by gel fraction, swelling ratio, TGA and FTIR spectroscopy. The results showed the ratio of CMC and SSS 1:0 gave the highest gel fraction, compared with other ratios. The swelling capacity increased by increasing SSS content due to the presence of [sbnd]SO₃Na, [sbnd]OH groups in gel structure. The FTIR spectrum of CMC/SSS gel showed the new absorption peaks at 1034 and 1012 cm⁻¹ corresponds to [sbnd]SO₃Na group. The metal ion adsorption capacity of CMC/SSS gel was investigated. The grafted gel effectively removed metal ions, especially Cr and Pb. The effects of hydrogel composition, contact time, and initial concentration on the adsorption capacity of the grafted hydrogels were studied. The adsorption kinetics and equilibrium isotherms were investigated using pseudo-second-order model and Langmuir model.

DOI： 10.1016/j.carbpol.2016.09.049

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

Through experiments, we studied defect turbulence, a type of spatiotemporal chaos in planar systems of nematic liquid crystals, to clarify the chaotic advection of weak turbulence. In planar systems of large aspect ratio, structural relaxation, which is characterized by the dynamic structure factor, exhibits a long-period oscillation that is described well by a combination of a simple exponential relaxation and underdamped oscillation. The simple relaxation arises as a result of the roll modulation while the damped oscillation is manifest in the repetitive gliding of defect pairs in a local area. Each relaxation is derived analytically by the projection operator method that separates turbulent transport into a macroscopic contribution and fluctuations. The analysis proposes that the two relaxations are not correlated. The nonthermal fluctuations of defect turbulence are consequently separated into two independent Markov processes. Our approach sheds light on diversity and universality from a unified viewpoint for weak turbulence.

DOI： 10.1103/PhysRevE.94.042701

Other Link： http://journals.aps.org/pre/abstract/10.1103/PhysRevE.94.042701

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

This study introduces a method to alleviate against non-point source water pollution which typically comprises both organic and inorganic pollutants. We synthesized a hydrogel adsorbent customized for simultaneous adsorption (and removal) of benzene and heavy metals ion pollutants. Two functional groups were successfully incorporated into the hydrogel system using solution polymerization and chemical cross-linking methods. The adsorbent was golden brown and insoluble in water, and its structural decomposition in the dry state started at around 175°C. Other thermal properties, hydrogel characterization and adsorption mechanism are described herein. Exploiting the alkylating chemistry of mono-aromatic compounds, this hydrogel successfully adsorbed benzene onto its heterogeneous surface. The strong nature of adsorption with a relatively faster equilibrium time progressed according to second order kinetic model. However, competitive heavy metal ions adsorption was a diffusion-limited process and the adsorption capacity increased not only with the solution pH but also with ionic size and the amount of metal ions’ electric charge. With both type of pollutants adsorbed onto PBA hydrogel, this work therefore opens up a possibility of synthesizing adsorbent systems customized for simultaneous removal of organic and inorganic pollutants in a multi-type polluted waters.

DOI： 10.1016/j.jece.2016.07.013

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

Stable energy resource supply is an important subject from the perspective of national security. In this sense, recovering uranium from seawater is important and profitable for the countries of which the land is surrounded by sea and is not endowed with energy resources such as Japan. However, the concentration of uranium dissolved in seawater is extremely low (ppb level) but the total amount of uranium is huge because of the tremendous seawater volume on the Earth. Therefore, in order to promote the efficiency of adsorbents capturing ppb-level uranium from seawater, the authors propose the utilization of hydrogel as a new adsorbent base material. In order to demonstrate the usefulness of the hydrogel for the ppb-level element-adsorption from seawater, the authors have developed the amidoxime incorporated hydrogel and have examined their ppb-level uranium capturing efficiency in the presence of other elements. From the experimental results, a potential for this purpose has been demonstrated by considerably high adsorption functionality.

DOI： 10.1016/j.pnucene.2015.04.017

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

We have experimentally investigated the viscosity of nematic liquid crystal mixtures of p-methoxybenzylidene-p′-n-butylaniline (MBBA) and p-ethoxybenzylidene-p′-cyanoaniline (EBCA) in the presence of electroconvection under an ac electric field with 60 Hz. Although the viscosity of the mixtures with negative dielectric anisotropy shows a characteristic decrease in the high-voltage regime, that with positive dielectric anisotropy shows a monotonic increase as the applied voltage is increased. The experimental results suggest that the decrease in viscosity observed only for the mixtures with negative dielectric anisotropy is attributed to the negative contribution of electric stress caused by the anisotropic director distribution of the turbulent state.

DOI： 10.7566/JPSJ.85.074002

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

Several kinds of acrylic-acid-grafted-starch (starch/AAc) hydrogels were prepared at room temperature (27°C) by applying 5, 10, 15, 20, and 25 kGy of gamma radiation to 15% AAc aqueous solutions containing 5, 7.5, and 15% of starch. With increment of the radiation dose, gel fraction became higher and attained the maximum (96.5%) at 15 kGy, above which the fraction got lowered. On the other hand, the gel fraction monotonically increased with the starch content. Swelling ratios were lower for the starch/AAc hydrogels prepared with higher gamma-ray doses and so with larger starch contents. Significant promotions of the swelling ratios were demonstrated by hydrolysis with NaOH: 13632 ± 10 % for 15 kGy radiation-dosed [5% starch/15% AAc] hydrogel, while the maximum swelling ratio was 200% for those without the treatment. The authors further investigated the availability of the starch/AAc hydrogel as an adsorbent recovering dye waste from the industrial effluents by adopting methylene blue as a model material; the hydrogels showed high dye-capturing coefficients which increase with the starch ratio. The optimum dye adsorption was found to be 576 mg per g of the hydrogel having 7.5 starch and 15% AAc composition. Two kinetic models, (i) pseudo-first-order and (ii) pseudo-second-order kinetic models, were applied to test the experimental data. The latter provided the best correlation of the experimental data compared to the pseudo-first-order model.

DOI： 10.1155/2016/9867859

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

Two types of spatiotemporal chaos in the electroconvection of nematic liquid crystals, such as defect turbulence and spatiotemporal intermittency, have been statistically investigated according to the Lagrangian picture. Here fluctuations are traced using the motion of a single particle driven by chaotic convection. In the defect turbulence (fluctuating normal rolls), a particle is mainly trapped in a roll but sometimes jumps to a neighboring roll. Its activation energy is then obtained from the jumping (hopping) rate. This research clarifies that diffusion in the defect turbulence regime in electroconvection can be regarded as a kind of hopping process. The spatiotemporal intermittency appears as a coexistent state of ordered grid domains and turbulent domains. The motion of a single particle shows weak and strong diffusion, respectively, in the ordered and turbulent domains. The diffusion characteristics intermittently change from one to another with certain durations as the domains change. This research has found that the distribution function of the duration that a particle remains in an ordered area has a power-law decay for which the index is different from that obtained by the Eulerian measurement.

DOI： 10.1103/PhysRevE.92.032909

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

The responses of soft-mode turbulence, a kind of spatiotemporal chaos seen in electroconvection of a nematic liquid crystal, to alternating-current magnetic fields is investigated to uncover the dynamical properties of spatiotemporal chaos. The dynamical responses can be measured by an order parameter, Mp(t), which indicates ordering in the convective roll pattern induced by the magnetic field. Determined by properties of the liquid crystal in a magnetic field, Mp(t) oscillates in accordance with the square of the magnetic field. The relaxation time of the system was obtained by fitting the frequency dependence of the complex susceptibility for the pattern obtained from the oscillation of Mp(t) to the Debye-type relaxation spectra. However, for the high-frequency regime, the susceptibility deviates from the spectra because slow and large fluctuations of Mp(t) contribute to the oscillation. The properties of this type of fluctuation were investigated by introducing a dynamic ordering parameter defined as the period average of Mp(t).

DOI： 10.1103/PhysRevE.92.012916

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

Tunable transport of tiny objects in fluid systems is demanding in diverse fields of science such as drug delivery, active matter far from equilibrium, and lab-on-a-chip applications. Here, we report the directed motion of colloidal particles and self-assembled colloidal chains in a nematic liquid crystal matrix using electrohydrodynamic convection (EHC) rolls. The asymmetric distortion of the molecular orientation around the particles results-for single particles-in a hopping motion from one EHC roll to the next and-for colloidal chains-in a caterpillar-like motion in the direction perpendicular to the roll axes. We demonstrate the use of colloidal chains as microtraction engines for the transport of various types of microcargo. This journal is

DOI： 10.1039/c4sm01354a

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

Ultraweak biophoton emission originates from the generation of reactive oxygen species (ROS) that are produced in mitochondria as by-products of cellular respiration. In healthy cells, the concentration of ROS is minimized by a system of biological antioxidants. However, heat shock changes the equilibrium between oxidative stress and antioxidant activity, that is, a rapid rise in temperature induces biophoton emission from ROS. Although the rate and intensity of biophoton emission was observed to increase in response to elevated temperatures, pretreatment at lower high temperatures inhibited photon emission at higher temperatures. Biophoton measurements are useful for observing and evaluating heat shock.

DOI： 10.1371/journal.pone.0105700

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

Much of early research on chaos from the viewpoint of physics was performed using spatially confined convective systems. In spatially extended convective systems, on the other hand, spatiotemporal chaos occurs. However, there is no unified definition for the term spatiotemporal chaos as for chaos. To unify definition, a property common to the three kinds of spatiotemporal chaos observed in electroconvection of nematic liquid crystals is presented.

DOI： 10.5047/forma.2014.005

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

Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) using hydrolyzed acrylamide (AAm)-grafted polyethylene terephthalate (PET) films was examined to explore the potential reuse of waste PET materials. Selective recovery of Hg(II) from a mixture of soft acids with similar structure, such as Hg(II) and Pb(II), is important to allow the reuse of recovered Hg(II). An adsorbent for selective Hg(II) adsorption was prepared by γ-ray-induced grafting of AAm onto PET films followed by partial hydrolysis through KOH treatment. The adsorption capacity of the AAm-grafted PET films for Hg(II) ions increased from 15 to 70 mg/g after partial hydrolysis because of the reduction of hydrogen bonding between -CONH₂ groups and the corresponding improved access of metal ions to the amide groups. The prepared adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The absorbent film showed high selectivity for the adsorption of Hg(II) over Pb(II) throughout the entire initial metal concentration range (100-500 mg/L) and pH range (2.2-5.6) studied. The high selectivity is attributed to the ability of Hg(II) ions to form covalent bonds with the amide groups. The calculated selectivity coefficient for the adsorbent binding Hg(II) over Pb(II) was 19.2 at pH 4.5 with an initial metal concentration of 100 mg/L. Selective Hg(II) adsorption equilibrium data followed the Langmuir model and kinetic data were well fitted by a pseudo-second-order equation. The adsorbed Hg(II) and Pb(II) ions were effectively desorbed from the adsorbent film by acid treatment, and the regenerated film showed no marked loss of adsorption capacity upon reuse for selective Hg(II) adsorption.

DOI： 10.1080/10934529.2014.882209

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

In the present study, the γ-ray induced grafting of acrylamide (AAm) onto poly(ethylene terephthalate) (PET) films and the resulting changes in properties, including the Hg(II)-capturing functionality, were investigated. No grafting was observed on pristine PET films. Therefore, the films were treated with dimethyl sulfoxide (DMSO) before the γ-ray grafting with the goal of facilitating grafting; some of the samples were pretreated at high temperature (100-160 °C) and showed a considerable increase in the adsorption of AAm from solution. The highest graft yield obtained in the present study was 15.5% for the DMSO specimens pretreated at 140 °C and γ-ray irradiated with a 100-kGy total dose (1-kGy h-1 dose rate) in 50 wt% AAm-monomer solutions in the presence of 1 wt% FeCl 3 (polymerization inhibitor). In addition to the promotion of the graft yield, the formation of micropores in the DMSO-pretreated specimens was found during the optical microscopy investigations. This structural change is hypothesized to assist the adsorption and γ-ray grafting of AAm to PET. The AAm-grafted PET films prepared using DMSO pretreatment showed high removal efficiency for Hg(II) ions, whereas the pristine PET film showed no uptake, reflecting these changes.

DOI： 10.1038/pj.2014.12

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

Nonthermal Brownian motion is investigated experimentally by injecting a particle into soft-mode turbulence (SMT), in the electroconvection of a nematic liquid crystal. It is clarified that the particle motion can be classified into two phases: fast motion, where particles move with the local convective flow, and slow motion, where they are carried by global slow pattern dynamics. We propose a simplified model to clarify the mechanism of the short-time and asymptotic behavior of diffusion. In our model, the correlation time is estimated as a function of a control parameter E. The scaling of the SMT pattern correlation time, τ_d∼E^-1, is estimated from the particle dynamics, which is consistent with a previous report observed from the Eulerian viewpoint. The origin of the non-Gaussian distribution of the displacement in the short-time regime is also discussed and an analytical curve is introduced that quantitatively agrees with the experimental data. Our results clearly illustrate the characteristics of diffusive motion in SMT, which are considerably different from the conventional Brownian motion.

DOI： 10.1103/PhysRevE.88.042147

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

We report new results about a type of electrohydrodynamic instability, the prewavy instability, in a homeotropic nematic liquid crystal in a high-frequency electric field. This instability is seen in the form of a series of bright and dark stripes in between two crossed polarizers. The stripe formation corresponds to the periodic modulation of the rotation angle of the director in the xy-plane with periodicity along the x-direction. The dynamical behavior of prewavy patterns near the nematic-isotropic transition is reported. We found that the isotropic phase, due to the Joule heating effect, starts to grow in the dark stripes, i.e., in the vicinity of in-plane rotation angle α = 0.

DOI： 10.7566/JPSJ.82.044601

Language：English   Publishing type：Research paper (other academic)  

Soft-mode turbulence (SMT) is the spatiotemporal chaos observed in homeotropically aligned nematic liquid crystals, where non-thermal fluctuations are induced by nonlinear coupling between the Nambu-Goldstone and convective modes. The net and modal relaxations of the disorder pattern dynamics in SMT have been studied to construct the statistical physics of nonlinear nonequilibrium systems. The net relaxation dynamics is well-described by a compressed exponential function and the modal one satisfies a dual structure, dynamic crossover accompanied by a breaking of time-reversal invariance. Because the net relaxation is described by a weighted mean of the modal ones with respect to the wave number, the compressed-exponential behavior emerges as a superposition of the dual structure. Here, we present experimental results of the power spectra to discuss the compressed-exponential behavior and the dual structure from a viewpoint of the harmonic analysis. We also derive a relationship of the power spectra from the evolution equation of the modal autocorrelation function. The formula will be helpful to study non-thermal fluctuations in experiments such as the scattering methods.

DOI： 10.1063/1.4794604

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

Modal relaxation dynamics has been observed experimentally to clarify statistical-physical properties of soft-mode turbulence, the spatiotemporal chaos observed in homeotropically aligned nematic liquid crystals. We found a dual structure, dynamical crossover associated with violation of time-reversal invariance, the corresponding time scales satisfying a dynamical scaling law. To specify the origin of the dual structure, the memory function due to nonthermal fluctuations has been defined by a projection-operator method and obtained numerically using experimental results. The results of the memory function suggest that the nonthermal fluctuations can be divided into Markov and non-Markov contributions; the latter is called the turbulent fluctuation (TF). Consequently, the relaxation dynamics is separated into three characteristic stages: bare-friction, early, and late stages. If the dissipation due to TFs dominates over that of the Markov contribution, the bare-friction stage contracts; the early and late stages then configure the dual structure. The memory effect due to TFs results in a time-reversible relaxation at the early stage, and the disappearance of the memory by turbulent mixing leads to a simple exponential relaxation at the late stage. Furthermore, the memory effect due to TFs is shown to originate from characteristic spatial coherency called the patch structure.

DOI： 10.1103/PhysRevE.87.012505

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

We investigated whole-plant leaf area in relation to ontogenetic variation in leaf-size for a forest perennial herb, Cardiocrinum cordatum. The 200-fold ontogenetic variability in C. cordatum leaf area followed a power-law dependence on total leaf number, a measure of developmental stage. When we normalized for plant size, the function describing the size of single leaves along the stem was similar among different-sized plants, implying that the different-sized canopies observed at different times in the growth trajectory were fundamentally similar to each other. We conclude that the growth trajectory of a population of C. cordatum plant leaves obeyed a dynamic scaling law, the first reported for a growth trajectory at the whole-plant level.

DOI： 10.1371/journal.pone.0045317

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

The autocorrelation function of pattern fluctuation is used to study soft-mode turbulence (SMT), a spatiotemporal chaos observed in homeotropic nematics. We show that relaxation near the electroconvection threshold deviates from the exponential. To describe this relaxation, we propose a compressed exponential appearing in dynamics of glass-forming liquids. Our findings suggest that coherent motion contributes to SMT dynamics. We also confirmed that characteristic time is inversely proportional to electroconvection's control parameter.

DOI： 10.1103/PhysRevE.85.030701

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

We have studied the soft-mode turbulence (SMT), a type of spatiotemporal chaos observed in the electroconvection of the homeotropic nematic liquid crystals, induced by nonlinear interaction between the long-wave length Nambu-Goldstone modes and the short-wave length convective modes. By applying an external magnetic field H, the NG mode can be controlled and as a result an ordered pattern may be observed. Transiently it is achieved by the dynamical changes of the many domains consisting of regular rolls. Removing the magnetic field, then, the ordered state relaxes to its original SMT pattern. The transient dynamics of such a relaxation process is also investigated. An order parameter called as M _p is used as a quantitative indicator for the transient process. We reveal two regimes of relaxation process: regime I and regime II correspond to the superposition of the modes and the free rotation of wavevector q(r) of the electroconvective pattern, respectively.

DOI： 10.1143/JPSJ.81.024004

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

Randomly distributed offset charges affect the nonlinear current-voltage property via the fluctuation of the threshold voltage above which the current flows in an array of a Coulomb blockade (CB). We analytically derive the distribution of the threshold voltage for a model of one-dimensional locally coupled CB arrays and propose a general relationship between conductance and distribution. In addition, we show that the distribution for a long array is equivalent to the distribution of the number of upward steps for aligned objects of different heights. The distribution satisfies a novel Fokker-Planck equation corresponding to active Brownian motion. The feature of the distribution is clarified by comparing it with the Wigner and Ornstein-Uhlenbeck processes. It is not restricted to the CB model but is instructive in statistical physics generally.

DOI： 10.1103/PhysRevE.84.051137

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

Metal oxide nanowires formed via vapor-liquid-solid (VLS) process are promising nanoscale building blocks. Although understanding material transport pathways across three phases is crucial to realize well-defined oxide nanowires, such knowledge is unfortunately far from comprehensive. Here we investigate the material transport pathway in VLS grown MgO nanowires by utilizing spacing-controlled regular array. Defining the regular spacing of catalysts allows us to extract the information of transport pathway for each catalyst. We found the significant contribution of vapor phase transport pathway rather than the surface diffusion transport. This result highlights the critical role of re-evaporation process on VLS oxide nanowires.

DOI： 10.1063/1.3660246

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

We theoretically investigate the current-voltage (I-V) property of two-dimensional Coulomb blockade (CB) arrays by conducting Monte Carlo simulations. The I-V property can be divided into three regions and we report the dependence of the aspect ratio δ (namely, the lateral size N _y over the longitudinal one N_x). We show that the average CB threshold obeys a power-law decay as a function of δ. Its exponent γ corresponds to a sensitivity of the threshold depending on δ, and is inversely proportional to N_x (i.e., δ at fixed N _y). Further, the power-law exponent ζ, characterizing the nonlinearity of the I-V property in the intermediate region, logarithmically increases as δ increases. Our simulations describe the experimental result ζ = 2:25 obtained by Parthasarathy et al. [Phys. Rev. Lett. 87 (2001) 186807]. In addition, the asymptotic I-V property of one-dimensional arrays obtained by Bascones et al. [Phys. Rev. B 77 (2008) 245422] is applied to two-dimensional arrays. The asymptotic equation converges to the Ohm's law at the large voltage limit, and the combined tunneling-resistance is inversely proportional to δ. The extended asymptotic equation with the first-order perturbation well describes the experimental result obtained by Kurdak et al. [Phys. Rev. B 57 (1998) R6842]. Based on our asymptotic equation, we can estimate physical values that it is hard to obtain experimentally.

DOI： 10.1143/JPSJ.80.114704

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

Chaotic patterns in electroconvection of homeotropic nematics, soft-mode turbulence (SMT), and the related spatiotemporal chaos (STC) are discussed, and the quantitative definition of the patterns is considered. The order parameter S, obtained directly from the 2D spectra of the patterns, is introduced. The contribution of the Nambu-Goldstone mode and the increase in pattern regularity under the influence of an external magnetic field H are evaluated. We propose a schematic phase diagram of STC patterns based on the value of S.

DOI： 10.1103/PhysRevE.84.011709

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

The mechanism of the solidification of compound materials, such as oxide crystals, in a vapor-liquid-solid (VLS) system is investigated by model molecular dynamics simulation. A simple model for the VLS growth of a compound crystal is proposed to clarify the general mechanism of how a liquid solvent catalyzes the growth rate. We find that the nucleation process at the solid surface is responsible for limiting the growth rate, and that the solvent catalyzes the nucleation by reducing the critical nucleation size at the liquid-solid interface. Our theoretical suggestion that the ratio of the vapor-solid (VS) growth rate to the VLS growth rate strongly depends on the supply rate qualitatively agrees well with the experimental result. Finally, we simulate the entire process of VLS nanowire formation.

DOI： 10.1103/PhysRevE.83.061606

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

We have found an unusual and unexpected link between micro- (nematic director) and macro- (velocity) fields in nematodynamics, which exhibits itself in extended defects of a new type. In particular, we have shown that black lines (BLs) observed in electroconvection of a homeotropically aligned nematic layer are simultaneously Bloch's domain walls for the director field and lines of zero velocity intersecting a roll pattern for the convection. A detailed experimental study revealing the fine structure of BLs and their point defects is presented.

DOI： 10.1103/PhysRevE.83.022701

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

Controlling and understanding an impurity doping on semiconductor oxide nanowires grown by the vapor-liquid-solid (VLS) method remains an important challenge. Homogeneous dopant distribution within oxide nanowires has been assumed without the direct evaluations to interpret the transport properties. Here we report the direct measurements of dopant distributions for Ta-doped SnO₂ nanowires. We find that differences in dopant incorporations between VLS and vapor-solid growth processes give rise to a heavily doped shell surrounding an underdoped core. Thus, understanding the dopant incorporation pathways is essential to designing and controlling impurity doping on VLS grown oxide nanowires.

DOI： 10.1063/1.3549703

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

We investigate the response of electroconvective patterns to an external magnetic field H in a homeotropic nematic system where spatiotemporal chaos called soft-mode turbulence (SMT) occurs. The pattern ordering M_p, which shows pattern regularity in SMT, increases with the magnetic field H due to the suppression of the azimuthal rotational freedom. Three regions in the H-dependence of M_p are found: the zero regime, the steep increase regime and the saturated regime. In the steep increase regime, M_p shows a linear relation with H̄², from which the susceptibility χ_p for the pattern ordering is obtained.

DOI： 10.1143/JPSJ.79.123001

Language：English   Publishing type：Research paper (other academic)  

We investigate the response of electroconvective patterns to an external magnetic field H in a homeotropic nematic system where spatiotemporal chaos called the soft-mode turbulence (SMT) occurs. We introduce new order parameter O_p, obtained directly from the amplitude spectrum of the patterns. We measure the degree of regularity of patterns under influence of H using O _p and compare with the pattern ordering M_p obtained from analogy with the magnetization in 2D XY model. Our new order parameter O _p is well proportional to M_p.

DOI： 10.1063/1.3537932

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

Impurity doping on semiconductor nanowires formed via vaporliquidsolid (VLS) mechanism has been investigated with the intention being to control the transport properties. Here we demonstrate that an addition of excess impurity dopants induces a mesostructure of long range periodic arched-shape in Sb-doped SnO₂ nanowires. The microstructural and composition analysis demonstrated the importance of the presence of impurities at the growth interface during VLS growth rather than the dopant incorporation into nanowires, indicating kinetically induced mechanisms.

DOI： 10.1016/j.jcrysgro.2010.08.011

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

The ability to control oxide nanowires via vapor-liquid-solid (VLS) mechanism remains an important challenge to explore various applications of oxide nanowires. Here we demonstrate the crucial roles of surrounding oxygen on VLS grown SnO₂ nanowires. When the partial pressure of surrounding oxygen is relatively low, the oxygen mainly acts as an oxygen source, promoting VLS growth. While for relatively high oxygen partial pressures, vapor-solid (VS) growth emerges, suppressing nanowire growth. The findings as to the roles of surrounding oxygen on the inherent competition between VLS and VS growths are in principle rather universal for VLS grown nanowires of various oxides.

DOI： 10.1063/1.3474605

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

In the vapor-liquid-solid (VLS) nanowire growth, nanowires can be constructed utilizing the difference in the mechanism of crystallization between the vapor-solid (VS) process (outside the solvent droplet) and the VLS process (inside the droplet). We performed a series of separate molecular dynamics simulations for a VLS system and a VS system under equivalent nonequilibrium conditions to clarify the different mechanisms of the solid growth process in both systems and to understand how a liquid substance can catalyze the solidification. The detailed observation of the chemical potential distribution during the steady solid growth state clearly outlines the processes that limit the growth rate. We found that the most dominant process limiting the growth rate is mass transport in the solvent liquid. We also show numerically and analytically that the mass transport rate is proportional to the diffusion constant and also to the solubility of in the solvent, and that a high solubility in the solvent can almost compensate for the disadvantage of a small diffusion constant. Although remarkable catalytic effect by the solvent at least in the linear nonequilibrium region could not be observed, our results suggest that the VLS process would catalyze the solid growth using liquid substance with higher solubility or in a nonlinear nonequilibrium state.

DOI： 10.1103/PhysRevE.82.011605

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

In the soft-mode turbulence (SMT) in electroconvection of homeotropic nematic systems, which is a kind of spatiotemporal chaos induced by nonlinear interaction between two two-dimensional (2D) XY fields, the Nambu-Goldstone modes, and the convective modes, a curious line structure called blackline has been discovered. We measured the density of the blackline as a function of control parameters, ac voltage, and frequency. By detailed observations and analysis, it is clarified that the blackline is a structure of the nematic director in the x-y plane and includes a sequence of point defects. We discussed similarity with the density of the blackline and that of the point defect in the conventional 2D XY model. The occurrence of this type of defects is only due to the symmetry in the SMT and independent of the properties of fluctuations.

DOI： 10.1103/PhysRevE.80.041701

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

This Letter reports a transition to spatiotemporal chaos (STC) in an electroconvective system of a homeotropic nematic liquid crystal under a symmetry breaking. The homeotropic system has a continuous symmetry which leads to the occurring of STC at a threshold for convection. When the symmetry is broken by an external field, a periodic pattern appears first and then STC appears at a higher transition point. The transition from the periodic pattern to STC is investigated by order parameters which were obtained from spectra of convective patterns. The results are compared with the recent theoretical researches for the damped Nikolaevskiy equation.

DOI： 10.1143/JPSJ.77.073001

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

For soft-mode turbulence, which is essentially the spatiotemporal chaos caused by the nonlinear interaction between convective modes and Goldstone modes in electroconvection of homeotropic nematics, a type of order-disorder phase transition was revealed, in which a new order parameter was introduced as pattern ordering. We calculated the spatial correlation function and the anisotropy of the convective patterns as a 2D XY system because the convective wave vector could freely rotate in the homeotropic system. We found the hidden order in the chaotic patterns observed beyond the Lifshitz frequency fL, and a transition from a disordered to a hidden ordered state occurred at the fL with the increase of the frequency of the applied voltages.

DOI： 10.1103/PhysRevLett.100.164503

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

This paper reports the control of spatiotemporal intermittency in an electroconvective system in a nematic liquid crystal. In the spatiotemporal intermittency, an ordered structure [the defect lattice (DL)] coexists with turbulence. Control of the spatiotemporal intermittency, in which the turbulent state changes to a DL, is achieved by a few percent amplitude modulation of the applied ac voltage. The optimal control frequency is equal to the intrinsic oscillation frequency of the DL. The transition from the turbulent state to a DL occurs not by nucleation of the DL domain, but by penetration of the DL domain into the turbulent one. Control of the spatiotemporal intermittency is achieved through a resonance of the DL oscillation with respect to the modulation frequency that leads to spatial entrainment.

DOI： 10.1103/PhysRevE.77.035205

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

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

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

Soft-mode turbulence (SMT) is a spatiotemporal chaos in electrohydrodynamic convective systems. It is caused by a nonlinear interaction between the convection mode and a Nambu-Goldstone mode, and bifurcates supercritically from a stationary uniform state. In this paper, we clarify that a spatial structure larger than a convective roll exists in SMT, which shows a patchlike domain structure characterized by wavevector directions. The dependence of the average size of the patch structure on the control parameter ε is given as ε^-1/2.

DOI： 10.1143/JPSJ.75.063801

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

Soft-mode turbulence (SMT) observed in the electroconvection of a nematic liquid crystal is a first experimental example of spatiotemporal chaos (STC) due to an additional Goldstone mode. In a nematic liquid crystal with homeotropic alignment a continuous rotational symmetry is broken by a kind of buckling instability of the alignment by applying voltage (control parameter), and this spontaneous symmetry breaking leads to a Goldstone mode. Further increasing the control parameter, electroconvective instability sets in and a roll pattern could be expected to appear. SMT however ensues by the coupling of the roll pattern with the Goldstone mode. SMT has the following properties: (i) SMT is one of the rare examples of STC appearing via single supercritical bifurcation directly from a quiescent state. With decreasing the control parameter, the correlation time of the chaotic fluctuation becomes longer and diverges at the bifurcation point, that is, the fluctuations become soft, (ii) SMT is the STC in respect to the directions of convective wavevector, and patches which are the areas with the same directions appear, (iii) The averaged size of the patch, as well as the the correlation length, becomes larger with decreasing the control parameter from the above of threshold. Furthermore we have investigated transport properties in SMT by observing non-thermal "Brownian motion" in order to elucidate a fluctuation theorem in dissipative systems. This study gives us important information about SMT from a viewpoint of the Lagrangian picture which is different from the properties of the Euler picture (pattern dynamics). We presented the time-scale dependence of diffusion constants obtained by a coarse-graining. The obtained result reflects that SMT pattern has two different length scales, rolls and patches. The diffusion of particles inside a patch is anomalous, i.e. Lévy diffusion, while the diffusion of inter-patches is normal. Thus the transport property of SMT is closely related with its spatial hierarchy.

DOI： 10.1143/PTPS.161.1

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

The transition to turbulence via 2-dimensional spatiotemporal intermittency observed in an electroconvective system of nematics is investigated experimentally. The area fraction of total turbulent domain was continuously increased with control parameter. Dynamic hysteresis in the transition is found by measurements for various ramp rate r of the control parameter, and it is vanished for r → 0.

DOI： 10.1143/PTPS.161.320

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

DOI： 10.1103/PhysRevE.70.066204

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

DOI： 10.1143/JPSJ.73.2917

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

DOI： 10.1080/15421400490434586

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (other academic)  

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

DOI： 10.1103/PhysRevE.66.031705

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

The ground state of the novel liquid crystal phase formed by achiral banana-shaped nitro-molecules and known as B7 is not understood. While spirals and myelins spontaneously appear on cooling from the isotropic liquid, neither mature to form B7 monocrystals. We tried suppressing the flow associated with these growth transients by applying large electric fields to thin samples (1-4 μm thick). While a field untwists some spirals and coarsens the less mobile myelin textures, it stimulates even more flow and a B7 texture with variable but exceedingly small length scales.

DOI： 10.1080/00150190214430

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

DOI： 10.1016/S0378-4371(02)00494-6

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

DOI： 10.1080/10587250108024981

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

DOI： 10.1143/JPSJ.70.2805

Language：English   Publishing type：Research paper (other academic)  

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

Two types of chevrons have been found in the conduction regime, as well as the conventional chevrons in the dielectric regime in homeotropically-aligned nematics. These two are named the defect-mediated chevron (DMC) and the defect-free chevron (DFC) by their structure changes. Two different bifurcation sequences are found with increasing the applied voltage, such as Fréedericksz transition → normal rolls → abnormal rolls → defect chaos →DMC for low frequencies and Fréedericksz transition → prewavy pattern → DFC for high frequencies. Moreover, the double periodicity of the chevrons (i.e., the short wavelength λ₁ of the striated rolls and the long wavelength λ₂ of the chevron bands) shows quite specific frequency dependence.

DOI： 10.1080/10587250108024024

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

DOI： 10.1103/PhysRevE.61.2769

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

DOI： 10.1080/10587259908026093

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

DOI： 10.1080/10587259908026101

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

DOI： 10.1080/10587259908026100

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

DOI： 10.1143/JPSJ.68.1567

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

Direct evidence for two different types of normal rolls and of zigzag rolls in homeotropically aligned nematic liquid crystals in a magnetic field is reported. The conventional normal rolls have the reflection symmetry in the xy plane. The instability, however, breaks the reflection symmetry [Formula Presented] on the director and then the abnormal rolls are expected to be observed. We have investigated the instability experimentally and discussed it in terms of the recent numerical results by Plaut et al. [Phys. Rev. Lett. 79, 2367 (1997)]. Due to the new instability, the abnormal zigzag rolls are also found below the Lifshitz frequency.

DOI： 10.1103/PhysRevE.58.7355

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

The experimental study on transition processes of the spatio-temporal chaos (STC) as well as periodic patterns in homeotropically aligned nematic liquid crystals is reported under superimposing magnetic fields with electric fields. The strong dependence of the threshold for STC on the strength of magnetic fields is observed above certain normalized voltage ε_th, where the two types of STC are found out below and beyond the characteristic value of the magnetic field H* = 620 G. The periodic patterns were observed for the normalized voltage ε below ε_th. Below H* the soft-mode turbulence appears due to the Goldstone mode related to a continuous rotational-symmetry which can be controlled by the application of H. Beyond H*, the conventional STC called defect turbulence, which is similar to STC in the planar system, is observed.

DOI： 10.1143/JPSJ.67.1948

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

The systematic experimental study of direct transition “nonconvective state — spatiotemporal chaos” in electrohydrodynamic convection of a homeotropically aligned nematic is carried out. The transient patterns, both below and beyond the Lifshitz point, are studied and classified. The patterns initially correspond to oblique and normal rolls, respectively. In all the cases the transition to chaos undergoes slow spatiotemporal modulations of the local roll orientation. This results in the final dynamical patterns isotropic on large spatial scales. The dynamics of the final patterns are also studied with a quantitative analysis of the power spectra of turbulent modes and their autocorrelation functions. The exponential decay of the correlations in time is proved.

DOI： 10.1143/JPSJ.66.3329

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

The experimental study of electroconvection in a homeotropically aligned nematic (MBBA) is reported. The system undergoes a supercritical bifurcation “rest state-spatiotemporal chaos.” The chaos is caused by long-wavelength modulation of the orientation of convective rolls. For the first time the observations both below and beyond the Lifshitz point are accompanied by quantitative analysis of temporal autocorrelation functions of turbulent modes. The dependence of the correlation time on the control parameter is obtained. A secondary bifurcation from normal to abnormal rolls is discussed.

DOI： 10.1103/PhysRevE.56.R6256

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

Pattern dynamics in a weakly nonlinear regime near the onset of the electrohydrodynamic instability (EHDl) is experimentally investigated in the homeotropic alignment of nematic liquid crystals, of which morphology is introduced. The wavy, chain and bamboo-chevron patterns are observed in homeotropic samples as new patterns. The Busse balloon is also obtained which is quite different from the conventional balloons in EHDI in planar liquid crystals.

DOI： 10.1080/10587259708041852

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

The quantitative experimental study of the Eckhaus instability in one-dimensional systems is carried out, employing electrohydrodynamic convection in a nematic layer. The obtained Busse balloon is in good agreement with that predicted by the Eckhaus theory. However, the observed changes of the wavenumber for unstable roll patterns, caused by the Eckhaus instability, as well as the growth rates for the corresponding spatial modes differ dramatically from those the theory yields for the most unstable Eckhaus modes. Possible reasons for the disagreement are discussed.

DOI： 10.1080/10587259708041848

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

The electrohydrodynamic pattern forming instability (EHC) driven by an ac voltage applied to a homeotropically aligned nematic liquid crystal layer is experimentally studied near onset. By controlling an external magnetic field, many different scenarios become accessible. For finite fields various regular convective structures are observed, which we call, for example, wavy, chain, and bamboo-chevron patterns. The various types are documented with the help of a phase diagram governed by the frequency and the strength of the applied ac voltage. In addition the stability regimes in the voltage-wavenumber plane (the "Busse balloon") are mapped out. One finds significant differences from the conventional planar case, for which a theoretical analysis is lacking so far. For zero magnetic field, on the other hand, no regular structure is observed, even immediately above the onset of EHC. A new spatiotemporally chaotic pattern called the soft mode turbulence directly appears via a supercritical bifurcation from the nonconvective state. This is due to the presence of the Goldstone mode related to the spontaneously broken rotational symmetry associated with the director component in the plane of the layer.

DOI： 10.1021/jp961539f

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

The process of annihilation of two point defects with opposite topological charges in a roll pattern is discussed for electrohydrodynamic convection in a nematic layer. It is shown that at the final stage of the process the distance between the centers of defects which are being annihilated varies as the square root of the time, down-counted from the annihilation moment. Such a scaling is associated with topological properties of the slowly varying complex amplitude of the order parameter and is suggested as a generic law for annihilation or spontaneous, barrierless nucleation of pairs of defects in extended systems. Experimental evidence of the scaling in the case of electrohydrodynamic convection in MBBA is obtained.

DOI： 10.1143/JPSJ.65.3419

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

The formation processes of a one-dimensional periodic pattern were investigated on the electrohydrodynamic convection of a nematic liquid crystal. Two kinds of processes for different initial conditions were observed. In the first initial condition the system was set to be the no-flow state in the absence of the applied field, and in the second the turbulent state under a strong field. The temporal change of the one-dimensional image intensity was measured after the amplitude of an ac electric field was jumped from these initial values to a value slightly above the critical one. The power spectrum function and the locally varying phase were calculated from the image intensity. The obtained results were compared with the numerical simulations of the diffusion equation.

DOI： 10.1143/jpsj.65.64

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

The interaction between the two convective systems separated by free lateral boundaries and the pattern formation have been studied. We have prepared a cell, where two identical convective subsystems with small aspect ratios are placed in the direction of the roll axis and coupled through the free lateral boundaries and the liquid crystal placed in-between. It is found that the evolution of convection in one subsystem is affected by the state of the other subsystem through the free boundaries. Moreover, the entrainment of the spatial pattern is observed.

DOI： 10.1080/10587259508041700

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

In the electro-hydrodynamic systems of nematic liquid crystals with free and rigid boundaries and a small aspect ratio, the pattern evolution process on applying the stepwise ac voltage was studied. The convective rolls appeared at the both lateral sides of the system, and evolved toward the center. It was found that the pattern is selected through the phase jump. The pattern in the free lateral boundary cell had more flexibility than in the rigid lateral boundary cell. The interactions between the two subsystems separated by free lateral boundary and the selection of the pattern were studied. It was found that the evolution and the selection of the pattern in a subsystem were affected by those in the other subsystem through the free boundary.

DOI： 10.1143/JPSJ.63.1698

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

The electro-hydrodynamic instability was investigated in a nematic liquid crystal cell with the free boundary condition on the sides and with a small aspect ratio. In such a free lateral boundary cell, a transition from quasi-periodicity to chaos was observed by measuring the angle-deflective oscillation when the applied voltage was increased. The correlation dimension in the chaotic state was obtained from the time sequence of the transmission intensity.

DOI： 10.1143/JPSJ.61.3950

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

A phase diagram and several physical quantities related to an isomorphous transition are studied on the basis of a Landau-type free energy function. Relationship with a two-sublattice model including an asymmetric double minimum potential is discussed.

DOI： 10.1143/JPSJ.60.1634

Event date： 2008.6

Presentation type：Oral presentation (general)  

Venue：九州大学・西新プラザ   Country：Japan  

Event date： 2007.9

Presentation type：Oral presentation (general)  

Venue：Physics Department, Gadjah Mada University, Jogjakarta   Country：Indonesia  

Presentation type：Oral presentation (general)  

Venue：International Conference Room I, The Clock Tower Centennial Hall, Kyoto University, Kyoto   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都大学数理解析研究所   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：Sendai International Center   Country：Japan  

Prewavy : A Director-Modulation Pattern in Nematic Liquid Crystals
Jong-Hoon HUH, Yoshiki HIDAKA, Yusril YUSUF, N?ndor ?BER, Tibor T?tH-KATONA, ?gnes BUKA and Shoichi KAI
18th International Liquid Crystal Conference (ILCC2000)

Presentation type：Oral presentation (general)  

Venue：京都大学数理解析研究所   Country：Japan  

Chevron-Wavy Pattern in Liquid Crystals
Yoshiki HIDAKA
RIMS Project 2000 "Reaction-diffusion systems: theory and applications" Interfaces, Pulses and Waves in Nonlinear Dissipative Systems

Presentation type：Oral presentation (general)  

Venue：弘済会館（東京都千代田区麹町5-1）   Country：Japan  

Event date： 2024.3

Language：Japanese  

Venue：東北大学(川内キャンパス)   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン（Zoom）   Country：Japan  

乱流境界における粒子輸送について研究を行うために, 液晶電気対流を用いた実験を行っている。今回は, 並行平板間に液晶を流したセルに電気対流・乱流を駆動し, ポンプで背景流れを駆動することで乱流境界に流入する粒子の振る舞いについて調べた結果を報告する。粒子が対流領域から乱流領域に斜めに侵入するとき, 境界面を通過する粒子と通過できず境界面に沿って流れる粒子を観測した。この現象について, 粒子径と乱流駆動力の大きさに注目して議論する。

Event date： 2024.3

Language：Japanese  

Venue：KDDI維新ホール   Country：Japan  

Event date： 2024.3

Language：Japanese  

Venue：KDDI維新ホール   Country：Japan  

Event date： 2024.3

Language：Japanese  

Venue：東北大学(川内キャンパス)   Country：Japan  

Event date： 2024.3

Language：Japanese  

Venue：東北大学(川内キャンパス)   Country：Japan  

Event date： 2024.3

Language：Japanese  

Venue：東北大学(川内キャンパス)   Country：Japan  

Event date： 2023.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎大学   Country：Japan  

"垂直配向したネマチック液晶に電圧を印加すると、液晶電気対流が生じて局所的なロール構造を保ちつつゆるやかな乱れが
自発的に生じるパターンが現れる。この様な弱い乱流は「ソフトモード乱流」と呼ばれており、少数の遅いモードの相互作用
によって生じる弱い乱流は、ある範囲のすべてのモードが関与する発達乱流とも、1つのモードが熱的に揺らぐ熱平衡系とも異なっている。ソフトモード乱流には、局所的な構造は保ったまま揺らいでいる「ノーマルロール」と、全体的に乱れている「オブリクロール」という２つの状態が存在する。ノーマルロールとオブリクロールで構造のダイナミクスが異なることは定性的に明らかだが、その特徴を定量化できていない。本研究の目的は、ソフトモード乱流の
ダイナミクスの特徴を解明することである。本研究では、対流パターンを粗視化して、
ロールの角度の時間変化や画像の相関係数に着目した。"

Event date： 2022.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本大学（黒髪南キャンパス）   Country：Japan  

"垂直配向したネマチック液晶に電圧を印加すると、液晶電気対流が生じて局所的なロール構造を保ちつつゆるやかな乱れが
自発的に生じるパターンが現れる。この様な弱い乱流は「ソフトモード乱流」と呼ばれており、少数の遅いモードの相互作用
によって生じる弱い乱流は、ある範囲のすべてのモードが関与する発達乱流とも、1つのモードが熱的に揺らぐ熱平衡系とも異なっている。ソフトモード乱流には、局所的な構造は保ったまま揺らいでいる「ノーマルロール」と、全体的に乱れている「オブリクロール」という２つの状態が存在する。ノーマルロールとオブリクロールで構造のダイナミクスが異なることは定性的に明らかだが、その特徴を定量化できていない。本研究の目的は、ソフトモード乱流の
ダイナミクスの特徴を解明することである。本研究では、対流パターンを粗視化して、
ロールの角度の時間変化や画像の相関係数に着目した。"

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井大学工学部   Country：Japan  

乱流は、古典物理学の範疇にありながら現在も物理学の最も重要な課題の一つである。ほとんどの乱流研究では、強く乱れた「発達乱流」が、統計的な取り扱いが可能なため、「理想的な乱流」として研究対象となってきた。一方、循環的流れ構造が規則的に配列した秩序構造が現れる対流系では、秩序構造がゆったりと乱れた「弱い乱流」が生じる。弱い乱流は、局所的な秩序と大局的な無秩序が共存しているため、その性質解明のためには発達乱流とは異なる観点が必要となる。また弱い乱流は、本来は決定論的時間発展方程式の示す不規則現象である「カオス」の検証実験の研究対象として、多くの研究が行なわれてきた。本講演では、弱い乱流を用いたカオスの検証実験の実例と、弱い乱流の示す「乱流拡散」についての研究例を紹介する。

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京工業大学   Country：Japan  

時間空間的に不規則な流れである乱流は乱流は完全に無秩序な発達乱流と秩序と無秩序が共存する弱い乱流の二種類存在する。本研究では弱い乱流について取り扱う。弱い乱流の研究対象の一つに、Nambu-Goldstoneモードと対流の相互作用により、対流ロールの向きqが時間空間的に不規則に変化する「ソフトモード乱流」がある。本研究ではソフトモード乱流の対流パターンを撮影し、画像解析することでqの方位角ψの分布関数を求め、実効温度で定量化することを目指す。

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン（Zoom）   Country：Japan  

電気対流効果によって生じるWilliams Domainは、液晶をディスプレイに応用するきっかけになった重要な現象であるが、印加電圧を上げると「Fluctuating Williams Domain」が生じる。これは、「弱い乱流」の一種として非線形物理学において重要な役割を果たしてきた。Fluctuating Williams Domainについて、われわれが最近行った研究を紹介する。

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京工業大学   Country：Japan  

ブラウン運動がミクロな熱揺らぎによって微粒子拡が拡散する現象であるのに対し、散逸構造のマクロな揺らぎにより微粒子が駆動され、非熱的に拡散される現象を非熱的ブラウン運動と呼ぶ。本研究では、液晶電気対流の弱い乱流を対象とし、外力下における非熱的ブラウン運動の観測を行うことによって、時空カオスによる輸送と拡散の統計的性質が外力によってどのように変わるかを調べた。

Event date： 2022.9 - 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京工業大学   Country：Japan  

乱流輸送の基礎研究を行うために、液晶電気対流を用いた実験を行っている。今回は、並行平板間に液晶を流した状態で電気対流・乱流を駆動し、対流構造と輸送特性について調べた結果を報告する。速度シアがある場合は、ディレクタと呼ばれる液晶分子配列の向きが速度シアと相互作用して、シアと垂直方向に対流ロール構造が制限されることを観測した。速度シアと対流が結合した速度場が生み出す、特徴的な速度分布関数についても議論する。

Event date： 2022.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：核融合科学研究所   Country：Japan  

Event date： 2022.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

プレーナー系の液晶セルに電圧を印加すると周期対流パターンが生じ、印加電圧を増加させると対流パターンが揺らいだ状態である欠陥乱流が現れる。その乱流中に混入させた微粒子の追跡を行ない、さらに揺らぎの強さに対応する制御パラメータと微粒子にかかる外力の大きさを変化させることによって、揺らぎの存在する周期対流パターンにおける物質輸送の性質を解明した。

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

ネマッチック液晶に電圧を印加すると散逸構造である、液晶電気対流が生じる。プレーナー配向系では電圧に応じて様々な対流パターンが現れる。一方、液晶・高分子複合体は高分子ネットワークによって液晶配向を安定化する効果を利用した様々な研究が行われてきた。本研究では、３次元網目状の形状から高分子ネットワークを多孔質媒体として捉え、高分子ネットワークが液晶における散逸構造にどのような影響を与えるかを調べた。

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

液晶と高分子ネットワークに関する研究は、「高分子・液晶複合体」として多くの応用研究が行われてきた。一方、液晶に電圧を印加すると液晶電気対流が発生し、その電圧に応じて様々なパターンが観察される。この液晶電気対流が高分子ネットワークによってどのような影響を受けるかについて調べることが本研究の目的である。高分子ネットワークは、多孔質媒体として見なすことができる。多孔質媒体中の対流は地質学や工学において重要であり、多くの研究がなされてきたが、高分子ネットワークを用いた研究は新しい試みである

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

液晶電気対流における局所的な秩序構造を保つ弱い乱流において周期的な対流ロールパターンに欠陥が生じた欠陥乱流がある。欠陥乱流中に混入した微粒子は対流の流れに乗り、対流ロールによってトラップされるが、稀にロールの揺らぎによって、ロールを飛び越えて拡散する。本研究では欠陥乱流中の外力を印加した微粒子を観測し、その拡散の性質を明らかにした。

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

液晶電気対流を研究対象としており、ノーマルロールから欠陥乱流そして発達乱流に遷移する過程において、欠陥乱流の発生点の系のサイズ依存性や、欠陥を伴わず位相の滑らかな変化のみが生じる位相乱流へ転移する系の臨界サイズについて実験的に調べた。

Event date： 2020.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2020.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀大学　本庄キャンパス 教養教育１号館   Country：Japan  

液晶と高分子ネットワークは高分子/液晶複合体として様々な研究が行われている。高分子ネットワークは多孔質媒体の１種とみなされる。また、多孔質媒体中の対流は、地質学・工学的に重要である。本研究では、液晶電気対流に高分子ネットワークがどのような影響を与えるかについて調査した。

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀大学　本庄キャンパス 教養教育１号館   Country：Japan  

欠陥乱流における外力下の物質輸送として、液晶セルに微粒子を混入し、欠陥乱流を発生させ、微粒子に外力をかけ、その運動を追跡することで、微粒子の伝導機構を明らかにすることを目標とした。

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀大学　本庄キャンパス 教養教育１号館   Country：Japan  

水平配向したネマチック液晶に電圧を印加すると対流が発生し、印加電圧を上げると欠陥乱流が生じる。欠陥乱流が生じる閾値のシステムサイズ依存性から、弱い乱流への遷移過程の機構を明らかにすることを目的とした。

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：筑波大学 大学会館   Country：Japan  

ネマチック液晶に電圧を印加したときに現れる2種類の非平衡構造が、高分子ネットワークによってどのような影響を受けるかについて述べる。1つはHomeotropic系のアンビリック、もう1つはPlanar系の液晶電気対流である。前者は、高分子安定化の非平衡系への拡張と見なせる。後者は、多孔質媒体中の流体輸送現象と密接に関係する。

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン（Zoom）   Country：Japan  

ネマチック液晶に電圧を印加したときに現れる2種類の非平衡構造が、高分子ネットワークによってどのような影響を受けるかについて述べる。1つはHomeotropic系のアンビリック、もう1つはPlanar系の液晶電気対流である。前者は、高分子安定化の非平衡系への拡張と見なせる。後者は、多孔質媒体中の流体輸送現象と密接に関係する。

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学大学院工学研究院附属環境工学研究教育センター   Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学伊都キャンパス   Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学伊都キャンパス   Country：Japan  

Event date： 2018.12

Language：Japanese  

Venue：大分大学旦野原キャンパス   Country：Japan  

ホメオトロピック系の液晶電気対流では、液晶配向がNambu-Goldstone(NG)モードとして振る舞い、対流と相互作用することによりソフトモード乱流(SMT)という弱い乱流（時空カオス）が生じる。SMT中の微粒子の拡散は、粒子が対流ロールにトラップされるためにsubdiffusionになると予想されたが、実際は弾道的なsuperdiffusionが起こる。このメカニズムを解明するのが本研究の目的である。このsuperdiffusionは、粒子がロールにトラップされたままロール自体が運動することによって生じていると考えられる。そこで、SMTのパターン画像にPIV(Particle Image Velocimetry)の技術を応用してロールの大局的な動きを調べた。さらに、磁場を印加することによりNGモードを抑えた系のパターンに対して同様の解析を行い、このsuperdiffusionに対するNGモードの役割を明らかにする。

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岩手大学　上田キャンパス   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：弘前大学 文京町キャンパス   Country：Japan  

Event date： 2018.9

Language：Japanese  

Venue：大阪大学豊中キャンパス   Country：Japan  

Nikolaevskii方程式を解くことで現れる時空カオスは，弱い乱流と呼ばれるの状態の1つである．この乱流中での粒子運動をシミュレーションにより再現し，その解析結果から弱い乱流の性質について議論する．

Event date： 2018.9

Language：Japanese  

Venue：同志社大学京田辺キャンパス   Country：Japan  

Event date： 2018.7 - 2018.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyoto International Conference Center (ICC Kyoto)   Country：Japan  

Event date： 2018.6

Language：English   Presentation type：Oral presentation (general)  

Venue：東京大学本郷キャンパス 理学部1号館（西棟2F）207号室   Country：Japan  

Event date： 2018.6 - 2016.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島大学   Country：Japan  

Event date： 2018.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：山口大学　常盤キャンパス   Country：Japan  

Event date： 2018.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：山口大学　常盤キャンパス   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学　郡元キャンパス   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学　郡元キャンパス   Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Venue：仙台国際センター   Country：Japan  

Event date： 2017.7 - 2018.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Hotel Gołębiewski in Wisła   Country：Poland  

Event date： 2016.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡大学   Country：Japan  

Event date： 2016.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡大学   Country：Japan  

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪工業大学 大宮キャンパス   Country：Japan  

Event date： 2016.8

Language：English  

Venue：福井大学文京キャンパス アカデミーホール   Country：Japan  

Event date： 2016.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学大学院工学研究院附属 循環型社会システム工学研究センター多目的セミナー室   Country：Japan  

Event date： 2016.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学大学院工学研究院附属 循環型社会システム工学研究センター多目的セミナー室   Country：Japan  

Event date： 2016.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学大学院工学研究院附属 循環型社会システム工学研究センター多目的セミナー室   Country：Japan  

Event date： 2014.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：崇城大学   Country：Japan  

Event date： 2014.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀大学   Country：Japan  

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎大学 文教キャンパス   Country：Japan  

Event date： 2014.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島大学 理学部   Country：Japan  

Event date： 2014.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島大学 理学部   Country：Japan  

Event date： 2013.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：久留米工業大学   Country：Japan  

Event date： 2013.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：久留米工業大学   Country：Japan  

Event date： 2013.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪大学　豊中キャンパス   Country：Japan  

Event date： 2012.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：横浜国立大学　常盤台キャンパス   Country：Japan  

Event date： 2012.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Convention Center Rheingoldhalle, Mainz ,Germany   Country：Germany  

Event date： 2012.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Convention Center Rheingoldhalle, Mainz ,Germany   Country：Germany  

Event date： 2012.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Convention Center Rheingoldhalle, Mainz ,Germany   Country：Germany  

Event date： 2012.5

Venue：Baltimore, Maryland   Country：United States  

Event date： 2012.5

Presentation type：Oral presentation (general)  

Venue：Max Planck Institue for Physics of Complex System, Dresden   Country：Germany  

Event date： 2012.5

Venue：富山大学 五福キャンパス   Country：Japan  

Event date： 2012.5

Venue：富山大学 五福キャンパス   Country：Japan  

Event date： 2012.5

Presentation type：Oral presentation (general)  

Venue：富山大学 五福キャンパス   Country：Japan  

Event date： 2012.3

Presentation type：Oral presentation (general)  

Venue：関西学院大学 西宮上が原キャンパス   Country：Japan  

Event date： 2012.2

Presentation type：Oral presentation (general)  

Venue：京都大学 基礎物理学研究所 湯川記念館   Country：Japan  

Event date： 2011.11

Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター   Country：Japan  

Event date： 2011.5

Presentation type：Oral presentation (general)  

Venue：福井大学工学部知能システム工学科 総合研究棟I ４階知能システム演習室   Country：Japan  

Event date： 2011.5

Country：Japan  

Event date： 2011.4

Presentation type：Oral presentation (general)  

Venue：九州大学西新プラザ中会議室   Country：Japan  

Event date： 2011.2

Presentation type：Oral presentation (general)  

Venue：山中温泉 河鹿荘ロイヤルホテル   Country：Japan  

Event date： 2010.11 - 2011.11

Venue：京都大学 基礎物理学研究所   Country：Japan  

Event date： 2010.11 - 2011.11

Venue：京都大学 基礎物理学研究所   Country：Japan  

Event date： 2010.11 - 2011.11

Venue：京都大学 基礎物理学研究所   Country：Japan  

Event date： 2010.11

Venue：京都大学 基礎物理学研究所   Country：Japan  

Event date： 2010.11

Venue：京都大学 基礎物理学研究所   Country：Japan  

Event date： 2010.11

Presentation type：Oral presentation (general)  

Venue：Bandung Institute of Technology, Bandung   Country：Indonesia  

Event date： 2010.9

Presentation type：Oral presentation (general)  

Venue：北海道大学 高等教育機能開発総合センター   Country：Japan  

Event date： 2010.9

Presentation type：Oral presentation (general)  

Venue：九州大学医学部百年講堂   Country：Japan  

Event date： 2010.6

Presentation type：Oral presentation (general)  

Venue：東京学芸大学 20周年記念飯島同窓会館   Country：Japan  

Event date： 2010.5

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

Venue：九州大学大橋キャンパス   Country：Japan  

Event date： 2010.3

Presentation type：Oral presentation (general)  

Venue：岡山大学　津島キャンパス   Country：Japan  

Time Correlation in Soft-Mode Turbulence

Event date： 2010.3

Presentation type：Oral presentation (general)  

Venue：岡山大学　津島キャンパス   Country：Japan  

Magnetic Field Response of Pattern Ordering in Soft-Mode Turbulence

Event date： 2010.3

Presentation type：Oral presentation (general)  

Venue：Portland, Oregon, USA   Country：United States  

Event date： 2010.3

Presentation type：Oral presentation (general)  

Venue：Portland, Oregon, USA   Country：United States  

Event date： 2010.3

Presentation type：Oral presentation (general)  

Venue：Portland, Oregon, USA   Country：United States  

Event date： 2010.3

Presentation type：Oral presentation (general)  

Venue：Portland, Oregon, USA   Country：United States  

Event date： 2010.3

Presentation type：Oral presentation (general)  

Venue：Portland, Oregon, USA   Country：United States  

Event date： 2010.2

Presentation type：Oral presentation (general)  

Venue：キャンパスプラザ京都   Country：Japan  

Statistical Properties and Function of Correlated Noise

Event date： 2010.1

Presentation type：Oral presentation (general)  

Venue：Max Planck Institute for Physics of Complex System, Dresden, Germany   Country：Germany  

Hidden Order in a Spatiotemporal Chaotic System

Event date： 2009.12

Presentation type：Oral presentation (general)  

Venue：宮崎大学木花キャンパス   Country：Japan  

A New Type of Defect in Soft-Mode Turbulence

Event date： 2009.12

Venue：宮崎大学 木花キャンパス   Country：Japan  

Nonequilibrium Brownian Motion in an Electroconvective System in a Liquid Crystal

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：獨協医科大学 臨床医学棟10階ホール 〒321-0293栃木県下都賀郡壬生町北小林880   Country：Japan  

Nambu-Goldstone Mode and Spatiotemporal Chaos

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：九州大学応用力学研究所 基礎力学部門非線形力学分野   Country：Japan  

A New Type of Defect in Soft-Mode Turbulence

Event date： 2009.10

Presentation type：Oral presentation (general)  

Venue：九州大学西新プラザ大講義室   Country：Japan  

Fluctuation Theorem in Soft-Mode Turbulence

Event date： 2009.9

Presentation type：Oral presentation (general)  

Venue：熊本大学黒髪キャンパス   Country：Japan  

Fluctuation theorem and its limit in soft-mode turbulence

Event date： 2009.9

Presentation type：Oral presentation (general)  

Venue：東京農工大学小金井キャンパス   Country：Japan  

Order-Disorder Transition and Line Defects in Dissipative Structures of Liquid Crystals

Event date： 2009.8

Presentation type：Oral presentation (general)  

Venue：ホテルポールスター札幌，ノボテル札幌 2階「ソレイユ」   Country：Japan  

Nonlinear Macroscopic Fluctuation and Fluctuation Theorem in Dissipative Structures of Liquid Crystals

Event date： 2009.5

Presentation type：Oral presentation (general)  

Venue：立教大学池袋キャンパス（東京都豊島区）   Country：Japan  

Event date： 2009.1

Presentation type：Oral presentation (general)  

Venue：南紀白浜ラフォーレ   Country：Japan  

Event date： 2008.12

Presentation type：Oral presentation (general)  

Venue：大橋サテライトLUNETTE（福岡市）   Country：Japan  

Event date： 2008.10 - 2008.11

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

Venue：京都大学・芝蘭会館別館（国際交流会館）   Country：Japan  

Event date： 2008.3

Presentation type：Oral presentation (general)  

Venue：近畿大学本部キャンパス   Country：Japan  

Event date： 2007.9

Presentation type：Oral presentation (general)  

Venue：北海道大学   Country：Japan  

Event date： 2007.9

Presentation type：Oral presentation (general)  

Venue：北海道大学   Country：Japan  

Event date： 2007.9

Presentation type：Oral presentation (general)  

Venue：北海道大学   Country：Japan  

Event date： 2007.9

Presentation type：Oral presentation (general)  

Venue：Simon Fraser University, Vancouver   Country：Canada  

Event date： 2007.3

Presentation type：Oral presentation (general)  

Venue：鹿児島大学   Country：Japan  

Event date： 2006.3

Presentation type：Oral presentation (general)  

Venue：愛媛大学   Country：Japan  

Event date： 2005.2

Presentation type：Oral presentation (general)  

Venue：大阪市立大学工学部   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：Korea University, Seoul   Country：Korea, Republic of  

Pattern Formation in Nematic Liquid Crystal under a Rotating Magnetic Field
Yoshiki HIDAKA, Yasunori INO, Junko YAMAGUCHI and Shoichi KAI
APCTP International Workshop on Stochastic Dynamics and Pattern Formation in Biological Systems

Presentation type：Oral presentation (general)  

Venue：岩手大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：Bayreuth   Country：Germany  

Spatial Entrainment and Incommensurate Dynamics of Normal Rolls in Electroconvection of Nematics
Yoshiki HIDAKA, Nobuaki MORI and Shoichi KAI
Pattern Formation in Liquid Crystals (PFLC '99)

Presentation type：Oral presentation (general)  

Venue：Bayreuth   Country：Germany  

New Classification of Chevron Patterns and Two Routes of Their Formation Mechanisms in Homeotropic Nematics
Jong-Hoon HUH, Yoshiki HIDAKA and Shoichi KAI
Pattern Formation in Liquid Crystals (PFLC '99)

Presentation type：Oral presentation (general)  

Venue：早稲田大学国際会議場(井深ホール)   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：Sendai International Center   Country：Japan  

New Classification of Chevrons in Electroconvection in Homeotropically-Aligned Nematics
Jong-Hoon HUH, Yoshiki HIDAKA and Shoichi KAI
18th International Liquid Crystal Conference (ILCC2000)

Presentation type：Oral presentation (general)  

Venue：東京大学地震研究所   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：中央大学多摩キャンパス   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都大学数理解析研究所   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：Washington D.C.   Country：United States  

Electric Field Mediated Changes in B7 Growth Habits
Yusril YUSUF, Yoshiki HIDAKA, Shoichi KAI, Helmut R. BRAND, Patricia E. CLADIS, Wolfgang WEISSFLOG and Gerhard PELZL
The 8th Ferroelectric Liquid Crystal Conference

Presentation type：Oral presentation (general)  

Venue：名古屋大学工学部   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：広島大学附属中央図書館ライブラリーホール   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：中部大学(愛知県春日井市)   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：中部大学(愛知県春日井市)   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都大学数理解析研究所   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都大学数理解析研究所   Country：Japan  

Prewavy Insatbility in Nematic Liquid Crystal
Yoshiki HIDAKA, YUSRIL Yusuf, Jong-Hoon HUH, Shoichi KAI
Mathematical Aspects of Complex Fluids III

Presentation type：Oral presentation (general)  

Venue：京都大学数理解析研究所   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東北大学川内キャンパス   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：九州大学箱崎キャンパス   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：九州大学箱崎キャンパス   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：九州大学箱崎キャンパス   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：青森大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：青森大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：International Conference Room I, The Clock Tower Centennial Hall, Kyoto University, Kyoto   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：KKRホテル熱海   Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：中部大学　春日井キャンパス   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：中部大学　春日井キャンパス   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京工業大学 すずかけ台キャンパス   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京工業大学 すずかけ台キャンパス   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：関西大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢大学　角間キャンパス   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢大学　角間キャンパス   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：広島大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：日本大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：日本大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：Strasbourg   Country：France  

New Spatio-Temporal Chaos in Homeotropic Electroconvection beyond Lifshitz Point under superimposing Magnetic Fields
Jong-Hoon HUH, Yoshiki HIDAKA and Shoichi KAI
17th International Liquid Crystal Conference

Presentation type：Oral presentation (general)  

Venue：Strasbourg   Country：France  

Pattern Formation in Elecroconvection of Nematics under Spatially-Periodic Force
Yoshiki HIDAKA, Tsuyoshi FUJIMURA, Nobuaki MORI and Shoichi KAI
17th International Liquid Crystal Conference

Presentation type：Oral presentation (general)  

Venue：琉球大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：琉球大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：琉球大学   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：千里ライフサイエンスセンター   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都大学数理解析研究所   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都大学数理解析研究所   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都大学数理解析研究所   Country：Japan  

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

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：40

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：543

Type：Competition, symposium, etc. 

Number of participants：15

Type：Competition, symposium, etc. 

Type：Academic society, research group, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Other

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Other

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Lecture

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Lecture