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

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Microencapsulation of n-tetracosane, whose melting point is approximately 50 °C, in a silica shell has been performed through the sol–gel method using tetraethyl orthosilicate (TEOS) as the precursor for silica-shell formation. Additionally, two types of silane coupling agents were used to modify the surface of the microcapsules to change the wettability. The morphology of the microcapsules was observed by scanning electron microscopy. The chemical composition was characterized by Fourier transform infrared spectroscopy. The results confirmed the presence of n-tetracosane and silica in the synthesized microcapsules. Wettability analysis showed hydrophobic and hydrophilic features because of the added silane coupling agents. From the results of differential scanning calorimetry measurements, the encapsulation ratio of the microcapsules increased with decreasing TEOS/n-tetracosane ratio, and the highest encapsulation ratio was 87.1 % at a TEOS/n-tetracosane ratio of 0.25. The pH in the microcapsule solution was affected by addition of a silane coupling agent, and shifting the pH to the basic side lowered the encapsulation ratio owing to enhancement of silica condensation. After 100 differential scanning calorimetry cycles, there was no significant degradation in the phase-change temperatures and enthalpies, which confirmed the good phase-change stability and repeatability. Therefore, the microcapsules are a potential material for thermal-energy-storage systems to effectively utilize energy.

DOI： 10.1007/s10765-023-03179-1

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Microencapsulated n-tetracosane as a phase change material with an inorganic calcium carbonate (CaCO3) shell has been synthesized through a self-assembly process with varying pH value of a precursor solution, and the resultant materials were systematically investigated. Spherical microcapsules with a mean diameter of less than 3 μm were seen by microscopic observation. X-ray diffraction analysis revealed the presence of three CaCO3 polymorphs such as calcite, aragonite, and vaterite in the shell, and these compositions depended on the solution pH. This fact was also confirmed by Fourier transform infrared spectra and reflected in the surface morphology of microcapsules. The characterization of the phase change behavior has shown no significant change in the phase change temperatures and more than 170 mJ/mg of phase change enthalpies with the microcapsules synthesized at pH = 1. This enthalpy corresponds to 69.2% of encapsulation efficiency which is improved from the value reported by other microcapsules with CaCO3 shells. Thermal cycling analysis exhibited good reliability and durability of phase change phenomena in the long term. These results demonstrate a promising potential of microcapsules for developing thermal energy storage materials at a mild temperature range, which can be applied for waste heat recovery applications.

DOI： 10.1021/acs.energyfuels.2c03564

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A spraying system was constructed with a microencapsulated phase change material (MPCM) slurry as the working medium to weaken the adverse effects of the slurry's high viscosity and low thermal conductivity on heat transfer in a wall tube heat exchanger. The temperature distributions of pure water and MPCM slurry were first obtained through infrared thermal imaging in spraying. Furthermore, the latent heat use of MPCM slurry was investigated through a new method based on the temperature properties of the phase change fluid, in which the working and phase change temperature ranges are matched. The heat-mass transfer characteristics are compared and discussed with those of the base fluid, and the latent heat use of 10wt% MPCM slurry containing the core material n-docosane (C22H46). The experimental results indicate that the phase change enables the MPCM slurry droplets to maintain a higher temperature than a fluid with no phase change or base fluid. Different application modes (static and spraying) have correspondingly different phase change temperature ranges owing to supercooling, and the degree of matching between the working and phase change temperature ranges has a critical impact on the latent heat use of the MPCM slurry. Finally, comparing the heat transfer coefficients and Lewis numbers between the base liquid and MPCM slurry reveals that the phase change not only enhances the heat transfer but also slightly reduces water evaporation compared with pure water spraying.

DOI： 10.1016/j.ijheatmasstransfer.2022.123573

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

Droplet transportation using a wettability gradient surface has attracted much attention owing to applications such as in microfluidic devices. A surface with a spatial structural gradient was prepared through a simple and cost-effective process even though understanding of droplet behavior on the structure was still limited. Here, we report impinging droplet motion on a gradient wrinkled surface. Surfaces were prepared through hard film deposition on soft pre-strained polydimethylsiloxane (PDMS) with a mask installed with a slit to control the amount of deposition, which is related to the wavelength of the wrinkles. Droplets were impinged with varying position with respect to the structure, and the droplet motion was observed in the direction away from the region under the slit. We found an asymmetric contact angle and alternate motion on both sides of the three-phase contact line during the motion according to the gradient of the wrinkle wavelength. These results may help not only to understand the behavior of droplet impingement on a gradient structural surface but also to further develop applications using directional droplet transfer.

DOI： 10.1039/d1ra09244h

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10765-021-02944-4

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Other Link： https://link.springer.com/article/10.1007/s10765-021-02944-4/fulltext.html

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

Microencapsulated phase change material (MPCM) slurries are energy-carrier fluids. Their latent heat utilization has been investigated by a new method based on the temperature properties of the phase-change fluid, in which match of the working and phase-change temperature ranges is considered. Based on the working-temperature range (3–15 °C) in heat-exchange circulation, the dynamic heat-transfer characteristics and utilization of the MPCM slurry with the core material n-docosane (C22H46) are discussed. The experimental results indicate that the effects of the stirring rate and flow rate on the dynamic heat-transfer characteristics are similar to those of water, and they have little influence on utilization of the 10% MPCM slurry, whereas the corresponding effect of the concentration is relatively large. When investigating the effect of the concentration, it was found that a low phase-change ratio suppressed movement of the phase-change-temperature range owing to the residual solid core material acting as a crystal nucleus, while the heat-transfer performance and latent heat utilization of the MPCM slurry suppressed each other. The 10% MPCM slurry is the most suitable energy carrier fluid, but supercooling still needs to be resolved. The experimental results provide a reference for practical efficient application of MPCM slurries as energy carrier fluids.

DOI： 10.1016/j.icheatmasstransfer.2021.105788

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Language：Japanese   Publisher：The Heat Transfer Society of Japan  

DOI： 10.11368/tse.30.23

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

Phase change materials show great promise as a way of thermal energy storage. A number of alkanes and these mixtures with melting point below 50 °C have been investigated to develop the microcapsules. However, there have been few investigations aimed at harnessing heat from environmental temperatures around 50 °C. Here, n-tetracosane, which has a melting point of 51 °C, was successfully microencapsulated in a calcium carbonate shell through a self-assembly technique. The structural characterization was conducted by the method of Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy. The encapsulation ratio of the phase change material into the shell was estimated based on the mass loss of the microcapsules due to heating and the differential scanning calorimetry analysis. A maximum encapsulation ratio of 53% was achieved, and the effects of the encapsulation ratio on the effective thermal conductivity of the microcapsules were evaluated by a steady-state method. In addition, heating–cooling cycles were demonstrated in composites of the microcapsules and building plaster. Repeatable thermal energy storage and release characteristics were achieved suggesting that this material is a potential candidate material for management of high temperatures.

DOI： 10.1016/j.applthermaleng.2020.115512

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

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

There have been conflicting reports as to whether surface wettability is effective in the freezing delay enhancement of attached water droplets. It is an important problem in the development of anti-icing surfaces needed for applications, such as aircraft wings and infrastructures. Here, we prepared precooled ambient conditions and surfaces which included smooth, microstructured, and two nanostructured surfaces with hydrophobic coatings to create an environment closer to the actual environment and to avoid frost formation, which enhances wetting transition and nucleation. Static and dynamic wetting characteristics of each surface were investigated as the fundamental properties and the freezing behavior of precooled water droplets were observed. A distinct elongation of the freezing delay time was observed for droplets on nanostructured surfaces which have static contact angles >150°, in contrast to those on smooth and microstructured surfaces. However, the difference in droplet adhesion induced by nanostructures showed a negligible impact on freezing delay. These results indicated that the reduction of the actual contact area between the solid and liquid phases restricted ice nucleus formation.

DOI： 10.1021/acs.langmuir.9b01173

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

The hollow inside of a carbon nanotube (CNT) has great potential not only for flow rate enhancement of nanocapillary, but also for a material container which can be applied for drug delivery and nanoparticle infusion. However, these applications focus on after liquid infusion into CNTs, whereas the understanding of the filling process is still limited. We conducted capillary filling experiments using individual open-ended CNTs, which were stuck into an ionic liquid and visualized by scanning transmission electron microscopy. The results showed that the meniscus stopped inside the CNT, which is not predicted by the Lucas-Washburn equation. To explain this discrepancy, the intermolecular force between the liquid and CNT inner wall was proposed to provide an additional friction force. In addition, voids were observed in the liquid inside the CNT. The generation mechanism of voids was proposed to be induced by the instability of the thin liquid layer along the CNT inner surface caused by the advance of the three-phase contact line. The results of the present study increase our understanding of nanoscale capillary action.

DOI： 10.1021/acs.jpcc.8b06406

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The three-phase contact line (TPCL) motion during evaporation of nanofluid sessile droplet was experimentally investigated to reveal the effect of characteristic surface structure and dimensions of contained materials on evaporation profiles. Nano and microstructured surfaces were prepared through chemical treatment and two sizes of SiO2 spherical particles were used as deposition materials. The contact angle and contact base radius profiles were studied through captured side view images and the sessile droplet method. Discontinuous TPCL motion was observed on micro/nano hierarchical structure, while continuous contact line receding during evaporation was seen on nanostructured surface. In addition, nanofluid with low particle concentration showed large contact angle and contact radius jump relative to dense nanofluid. This finding shows that the increase the amount of deposited materials on the TPCL regions should lead the undeformable liquid-vapor interface, and it showed opposite trend compared to the result reported by flat surface. The result found in this study will help to understand the deposition patterns on the superhydrophobic surface which is an important issue for evaporation-driven supraparticles fabrication.

DOI： 10.1615/ihtc16.bae.022231

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Recently, thermal energy transport systems using the flow drag and heat transfer reduction effect have attracted a great deal of interest for reduction of flowing pump power and heat loss. The surfactant is the most important additive for practical use. However, there have been few studies on the flow drag reduction effect of organic brine with surfactant below 0°C. In our previous work, we demonstrated the flow drag and heat transfer reduction effect of some organic brines with the nonionic surfactant, oleyl hydroxyethyl amine oxide (ODEAO). However, the mechanism underlying flow drag reduction of organic brine with surfactant is not fully understood. In addition, it is difficult to apply ODEAO for practical use because it is rare and very expensive. This study was performed to investigate different nonionic surfactants exhibiting flow drag and heat transfer reduction effect of 50 mass% EG solution below 0°C. In this study, a complex of oleyl dimethyl amine oxide (C18DMAO) and o-toluic acid was used as the flow drag surfactant additive. In addition, a vortex inhibition test was performed to determine a suitable molar concentration ratio between C18DMAO and o-toluic acid for 50 mass% EG solution. At this suitable surfactant concentration, dynamic light scattering analysis indicated that the size of rod-like micelles of C18DMAO was in the range of 79 - 142 nm. Finally, the flow drag and heat transfer reduction effect of 50 mass% EG solution with C18DMAO and o-toluic acid were confirmed experimentally at 0°C and -10°C.

DOI： 10.1615/ihtc16.cov.021496

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society  

The three-phase contact line motion on a superhydrophobic surface through particle-laden sessile droplet evaporation was investigated. Sample surfaces with micro- and nanoscale structures were generated by various durations of chemical treatment and SiO2 spherical particles with different sizes were used as additives of test liquid. The contact angle and contact radius profiles were studied, and the discontinuous motion of those profiles on micro- and nanostructured hierarchical surfaces was observed, while it was not observed on a nanostructured superhydrophobic surface. Suspensions with low particle concentration induced a relatively large contact radius jump compared to the high-concentrated condition
in contrast, the previous report showed the opposite trend for flat surfaces. In order to explain this result, a simple explanation was provided - that the stacked particles at the contact line region suppressed to the deformation of the liquid-vapor interface near the contact line. This is confirmed by side-view images of the deposition results because the contact line region after evaporation of the dense suspension showed a large contact angle compared to that of the diluted suspension. In addition, deposition at the contact line region was observed by scanning electron microscopy to discuss the effect of the characteristic length scale of the surface structure and particles on the contact line motion. We believe that these results will help one to understand the deposition phenomenon during particle-laden droplet evaporation on the superhydrophobic surface and its applications such as evaporation-driven materials deposition.

DOI： 10.1103/PhysRevE.97.043113

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DOI： 10.11368/tse.26.19

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Hollow carbon nanotubes (CNTs) were impregnated with an ionic liquid, resulting in a composite core-shell nanostructure. Liquid infusion was verified by transmission electron microscopy and rigorous observations unveiled that the nanocomposite is stable, i.e., liquid did not evaporate owing to its low vapor pressure. A series of individual nanostructures were attached on T-type heat sensors and their thermal behavior was evaluated. The liquid core was found to reduce the thermal conductivity of the base structure, CNT, from ca. 28W/mK to ca. 15 W/mK. These findings could contribute to a better understanding of nanoscale thermal science and potentially to applications such as nanodevice thermal management and thermoelectric devices. Published by AIP Publishing.

DOI： 10.1063/1.4973488

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Thermal transport in carbon nanofibers (CNFs) was thoroughly investigated. In particular, individual CNFs were suspended on T-type heat nanosensors and their thermal conductivity was measured over a range of temperatures. Unexpectedly, thermal conductivity was found to be dependent on CNF wall thickness and ranging between ca. 28 and 43 W/(m.K). Further investigation of the CNF walls with high resolution electron microscopy allowed us to propose a tentative description of how wall structure affects phonon heat transport inside CNFs. The lower thermal conductivities, compared to other CNTs, was attributed to unique CNF wall structure. Additionally, wall thickness is related to the conducting lattice length of each constituent graphene cone and comparable to the Umklapp length. Hence, as the wall thickness and thus lattice length increases there is a higher probability for phonon scattering to the next layer. (C) 2016 Author(s).

DOI： 10.1063/1.4968831

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

The surface wettability of a liquid on the inner and outer surface of single carbon nanotubes (CNTs) was experimentally investigated. Although these contact angles on both surfaces were previously studied separately, the available data are of limited help to elucidate the effect of curvature orientation (concave or convex) on wettability due to the difference in surface structure. Here, we report on the three-phase contact region and wettability on the outer surface of CNT during the dipping and withdrawing experiment of CNT into an ionic liquid. Furthermore, the wettability on the inner surface was measured using a liquid within the same CNT. Our results show that the contact angle on the outer surface of the CNT is larger than that on the flat surface and that on the inner surface is smaller than that on the flat one. These findings suggest that the surface curvature orientation has a noticeable effect on the contact angle at the nanoscale because both inner and outer surfaces expose the same graphite wall structure and the contact line tension will be negligible in this situation. The presented results are rationalized using the free energy balance of liquid on curved surfaces.

DOI： 10.1021/acs.langmuir.6b01366

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Highly stable nanoscale gas states at solid/liquid interfaces, referred to as nanobubbles, have been widely studied for over a decade. In this study, nanobubbles generated on a hydrophobic Teflon amorphous fluoroplastic thin film in the presence and absence of hydrophilic carbon domains are investigated by peak force quantitative nanomechanics. On the hydrophobic surface without hydrophilic domains, a small number of nanobubbles are generated and then rapidly decrease in size. On the hydrophobic surface with hydrophilic domains, the hydrophilic domains have a significant effect on the generation and stability of nanobubbles, with bubbles remaining on the surface for up to three days.

DOI： 10.1002/cphc.201501181

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

Realizing surface wettability tuning at the submicron-scale resolution is expected to enable the fabrication of micro/nano-structured fluidic devices and is particularly important in nanobiotechnology and high-resolution printing. Herein, we propose an approach to modify the wettability of self-assembled monolayer surfaces using focused ion beam (FIB) irradiation. The contact angle of the irradiated region changed from hydrophobic to hydrophilic by increasing the ion dosage. The chemical composition and associated depth profile of the sample surfaces were analyzed by glow discharge-optical emission spectroscopy. The results indicated that the content of fluorine at the surface decreased after FIB irradiation of the samples. A submicron-scale hydrophobic-hydrophilic hybrid surface was then fabricated by forming hydrophilic dots with diameters of similar to 110 nm on a hydrophobic surface by FIB irradiation. The difference in wettability of the hydrophobic and hydrophilic areas on the surface was confirmed by microscale condensation and evaporation experiments. Condensed droplets with diameters of similar to 300 nm appeared on the surface according to the fabricated pattern, thus suggesting that condensation preferentially occurred on the hydrophilic dots than on the hydrophobic surface. Furthermore, tiny droplets remained on the hydrophilic dots following evaporation of the larger droplets. The current approach provides a means to control wettability-driven phenomena.

DOI： 10.1021/acs.jpcc.5b09019

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

Water condensation on a hydrophobic surface with nanoscale hydrophilic regions was investigated to reveal the condensation mechanism of submicron-scale droplets. This feature was found on the graphite step-terrace structured surface; step surfaces are more wettable relative to terrace surfaces, and it was precisely characterized using an atomic force microscope. Condensation experiments were conducted using an environmental scanning electron microscope and droplets were observed to line up on preferentially along the graphite steps. Observed droplets ranged from 150 to 300 nm in diameter and the droplet interval depends on the width of hydrophobic region. The heterogeneous nucleation theory was extended to consider attracted water molecules on hydrophilic step surface, which enable us to explain the current observed result under unsaturated condition. As a result, proposed theory shows qualitatively that narrower hydrophobic region induces short droplet interval. Our suggestion for design the hybrid hydrophilic-hydrophobic surface would enable the development of surface that will perform high heat transfer at dropwise condensation.

DOI： 10.1299/transjsme.14-00495

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Nanobubbles exist at solidliquid interfaces between pure water and hydrophobic surfaces with very high stability, lasting in certain cases up to several days. Not only semispherical but also other shapes, such as micropancakes, are known to exist at such interfaces. However, doubt has been raised as to whether or not the nanobubbles are gas-phase entities. In this study, surface nanobubbles at a pure waterhighly ordered pyrolytic graphite (HOPG) interface were investigated by peak force quantitative nanomechanics (PF-QNM). Multiple isolated nanobubbles generated by the solvent-exchange method were present on the terraced areas, avoiding the steps of the HOPG surface. Adjacent nanobubbles coalesced and formed metastable nanobubbles. Coalescence was enhanced by the PF-QNM measurement. We determined that nanobubbles can exist for a long time because of nanoscale contact angle hysteresis at the waterHOPG interface. Moreover, the hydrophilic steps of HOPG were avoided during coalescence, providing evidence that the nanobubbles are truly gas phase.

DOI： 10.1021/la5036322

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

Water condensation on a hybrid hydrophilic-hydrophobic surface was investigated to reveal nucleation mechanisms at the microscale. Focused ion beam (FIB) irradiation was used to change the wettability of the hydrophobic surface with 10 nm order spatial resolution. Condensation experiments were conducted using environmental scanning electron microscopy; droplets, with a minimum diameter of 800 nm, lined up on the FIB-irradiated hydrophilic lines. The heterogeneous nucleation theory was extended to consider the water molecules attracted to the hydrophilic area, thereby enabling explanation of the nucleation mechanism under unsaturated conditions. Our results showed that the effective surface coverage of the water molecules on the hydrophilic region was 0.1-1.1 at 0.0 degrees C and 560 Pa and was dependent on the width of the FIB-irradiated hydrophilic lines and hydrophobic area. The droplet nucleation mechanism unveiled in this work would enable the design of new surfaces with enhanced dropwise condensation heat transfer.

DOI： 10.1021/la503615a

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

Water condensation on a graphite surface was investigated at the micron and submicron scale by environmental scanning electron microscopy. The graphite comprised a hydrophobic terrace and hydrophilic step edges, of which the nanoscale structure was precisely measured by atomic force microscopy prior to the condensation experiments. The condensed droplets were preferentially aligned parallel to the step edges with a step height of 1 nm. The droplets featured a diameter of 150-300 nm at intervals greater than 150 nm. Shorter droplet intervals were realized by narrower terraces and higher steps. The current findings extend beyond the nucleation theory, whereby the effect of adsorbed water molecules on hydrophilic step edges was considered. The contact angle (i.e., 10°) of the nucleated droplet at its initial stage (with diameter in the nanoscale) was determined from the extended theory, and was consistent with direct observation of slightly grown droplets. The growth mechanism of the submicrometer-sized droplets was also investigated; under this scale regime, the three-phase contact line does not recede during coalescence.

DOI： 10.1615/IHTC15.cds.009177

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER SOC MECHANICAL ENGINEERS  

Heat transfer at solid-solid interface is very fascinating where no one knows the full mechanism which has a huge impact in many applications in engineering and science. In many kinds of interfaces, we treat a van der Waals contact of perfectly-smooth surfaces by using multi-walled carbon nanotubes (CNTs). Their thermal contact resistance (TCR) is estimated by comparing measured thermal conductivity of CNT specimen and numerical simulation result. The TCR per unit area is estimated as 1.58 similar to 3.33x10(-8) m(2)K/W at room temperature in vacuum, which is much higher than our previous result in air. It was also found that TCR is inversely proportional with the temperature to the 1.92th power different from the simple phonon model represented by the diffuse mismatch model.

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Condensation heat transfer is a widely-used technique for industrial applications represented by heat exchanger because of its high heat transfer coefficient. To enhance its performance, a suitable surface is required, where both condensation and droplet removal smoothly occur. In this study, we compared wettability of a graphene surface and an amorphous carbon surface. The result shows that an amorphous carbon surface is more hydrophilic. Then we prepared a graphite surface which has nanoscale hydrophilic regions in large hydrophobic area. We observed the submicron-scale droplet condensation occurs preferentially on the hydrophilic graphite step by using environmental scanning electron microscope (ESEM).

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Carbon nanotube is a promising material for thermal-management of micro devices because of its high intrinsic thermal conductivity. However, most bulk nanotubes show very low thermal conductivity due to the high thermal contact resistance. There are very few reliable experimental data for the contact issue of nanotubes. This paper uses three kinds of multi-walled carbon nanotubes; pristine, thermally-oxidized, and acidized nanotube. Each has unique nanoscale structure in their outermost surface. We measured thermal conductivity of their pellets and simultaneously conducted computational analysis treating random network model of spherocylinders. By comparing both results, thermal contact resistances between nanotubes are estimated and the effect of defected structure is discussed. The reliability of our method is also successfully confirmed compared with reported data using individual nanotubes.

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

Interfacial thermal transport of multi-walled carbon nanotubes (MWNTs) is investigated by using bulk pellet specimens. Steady-state conduction method gives thermal conductivity of 1 to 4 W/mK for the pellets with mass density from 0.2 to 0.35 g/cm(3). This low thermal conductivity is due to the thermal boundary conductance between the nanotubes. Computational analysis is conducted for the pellet modeled as a random network of spherocylinders (SCs) and calculated dependency of thermal conductivity on pellet density shows good agreement with experimental data when we treat non-uniform SCs. By comparing the experimental and computational results, the thermal boundary conductance between two MWNTs can be taken as 1.5x10(-8) W/K. This result agrees well with the reported data obtained by individual measurement, which suggests this simple method is applicable to probe the interfacial thermal phenomena of nanomaterials. An improved scaling law, k proportional to rho(2.14), for thermal conductivity of MWNTs aggregations is also proposed and discussed.

DOI： 10.1299/jtst.7.190

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Experimental investigations for sorption and desorption behaviors in a circular-tube fluidized bed were carried out using organic sorbent particles for the development of a desiccant air conditioning system. Mixing of the fluidized bed intensified with increasing velocity of the air flow passing through sorbent particles. The effective mass transfer coefficient increased with increasing air flow velocity. Additionally, a dehumidifying system of circulating fluidized beds with sorbent particles circulated by air flow was created to perform continuous dehumidification. Experiments were conducted to grasp the continuous dehumidification characteristics of the sorbent particles, and the dehumidification behavior was evaluated according to the sorption and desorption amount.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Heat transfer performance of dropwise condensation is higher than filmwise one due to droplet removal from the condensed surface. In order to further enhancement of its performance, removal of microscale droplet is a key issue. However, condensation mechanism at microscale on hydrophobic-hydrophilic hybrid surface is not understood, although all surfaces are consisted with those combinations. In this study, we conducted condensation experiments on a graphite surface at 0℃ and 550 to 600 Pa by using environmental scanning electron microscope (ESEM). Nanoscale step-terrace structures on graphite surface are obtained by using an atomic force microscope (AFM) before ESEM experiments. It was found that condensed droplets with diameter of 150 to 300 nm are lined up along step edges at over 150 nm intervals. In addition, we found that most droplets are on the steps of height of 1 nm and shorter droplet intervals are induced by higher steps and shorter terrace width. Our results were analyzed by an extended nucleation theory and we found that water molecules attracted on steps play an important role for droplet condensation.

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Carbon nanotubes (CNTs) have high intrinsic thermal conductivity and high surface-to-volume ratio, thus CNT-based fins is considered to be promising for hign performance device cooling. In addition, exploring the heat transfer between a CNT and gases is important not only for CNT-based gas sensors but also for scientific interest oi mterfacial heat transport. In this work, we have developed novel technique for measuring heat transfer coefficients between an individual carbon nanotube and surrounding gases (Air, N_2, Ar, He) using platinum hot film sensor. Measured heat transfer coefficients quantitatively show good agreement with estimated values by kinetic gas theory at atmospheric pressure but do not match with theoretical prediction at low pressure regime.

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Event date： 2023.10.14 - 2023.10.15

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Event date： 2023.9.24 - 2023.9.27

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Event date： 2023.9.10 - 2023.9.13

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Event date： 2023.9.6 - 2023.9.8

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Event date： 2023.9.6 - 2023.9.8

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2023.8.4 - 2023.8.8

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

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Event date： 2023.8.4 - 2023.8.8

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

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Event date： 2023.8.4 - 2023.8.8

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

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Event date： 2023.6.7

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

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Event date： 2023.5.25 - 2023.5.27

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2023.5.25 - 2023.5.27

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2023.5.25 - 2023.5.27

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2023.5.25 - 2023.5.27

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.10.31 - 2022.11.1

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.10.25 - 2022.10.27

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.10.25 - 2022.10.27

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.10.8 - 2022.10.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.10.8 - 2022.10.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.9.26 - 2022.9.30

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.9.26 - 2022.9.30

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.9.26 - 2022.9.30

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2022.9.7 - 2022.9.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.9.7 - 2022.9.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.9.7 - 2022.9.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.9.7 - 2022.9.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.5.18 - 2022.5.20

Language：Japanese   Presentation type：Poster presentation  

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Event date： 2022.5.18 - 2022.5.20

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.5.18 - 2022.5.20

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.5.18 - 2022.5.20

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.3.4

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.3.4

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.3.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.3.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.11.29 - 2021.11.30

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.11.29 - 2021.11.30

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.10.9 - 2021.10.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.10

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2021.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.5.25 - 2021.5.27

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.10

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.6

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.6

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.5.25 - 2020.5.27

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.12

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.12

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.11.19 - 2019.11.21

Language：Japanese   Presentation type：Poster presentation  

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Event date： 2019.10.28 - 2019.10.30

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.9.11 - 2019.9.13

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.12

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2018.12

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2018.12

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2018.12

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2018.12

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.10.30 - 2018.11.1

Language：Japanese   Presentation type：Poster presentation  

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Event date： 2018.10

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.8

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2018.6

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2018.5.29 - 2018.5.31

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2018.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2017.5.24 - 2017.5.26

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2016.5.24 - 2016.5.26

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2015.10.24 - 2015.10.25

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2015.6.3 - 2015.6.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2014.7.28 - 2014.7.30

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2014.5.21 - 2014.5.23

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2013.10.19 - 2013.10.20

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2013.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2012.11

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2012.5.30 - 2012.6.1

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2011.11.21 - 2011.11.23

Language：Japanese   Presentation type：Oral presentation (general)  

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

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

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

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

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

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

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