Heat (energy released) and cool (energy absorbed) are two types of PCMs that have been developed and adopted in clothing and textiles design. Many special function and smart textiles have adopted this concept such as: ski wear, diver dry suits, underwear, socks, hats, masks, gloves, shoes, firefighters’ gear, bedding like sheets and pillowcases, and medical clothing. This paper discusses current PCM applications in clothing and explores future usage.
Studies on highly conductive LB films based on ditetradecyldimethylammonium-Au(dmit)2 [2C14-Au(dmit)2] salt have been reviewed. The room temperature conductivity of the 2C14-Au(dmit)2 LB film is as high as 40 S/cm after electro-oxidation. The resistance vs. temperature plot depends on the gap distance for the measurement. A weak metallic behavior is seen from room temperature down to 210-250 K, when the gap distance is 500 μm, while it extends down to 56-106 K, when the gap distance is 5 μm, indicating that the disorders in the film are important limiting factors for the macroscopic resistance. The data of the complex magnetic susceptibility (χ’ + iχ”) suggest the existence of the Meissner state below 3.9 K. Although some samples show resistance drop on cooling below 4 K, the typical resistance behaviors are of activation type at the lower temperature. We consider that disorders such as grain boundaries and/or defects are important limiting factors that should be solved to improve the electrical conduction toward the realization of global superconductivity.
Nanofluid is a new class of heat transfer fluids containing nano-sized particles, fibers, or tubes that are stably suspended in a carrier liquid. In this article, carbon black nanofluids were prepared by dispersing the pre-treated carbon black powder into ethylene glycol. The thermal conductivities, rheological behaviors and photo-thermal properties of the nanofluids were investigated. The results showed that the thermal conductivities of carbon black nanofluids increased with particle loading and temperature. The nanofluids performed a shear thinning behavior. The shear viscosity increased with particle loading while decreased with temperature at the same shear rate. Carbon black nanofluids had good absorption ability of solar energy and could effectively enhance the solar absorption efficiency.
As well as the ingredient compositions, strongly temperature dependent features of the turbidities of poly(acrylamide/malic acid) (AAm/MA) gels have been found in the light transmissivity measurements (λ =600 nm). In addition, nano-scale fractal structures in the turbid gels have been recognized by the small angle X-ray scattering (SAXS) measurements at room temperature; and from a positive correlation between the degree of the turbidity and the fractal dimension derived from the SAXS profiles, it has been concluded that the origin of the increase in the light scattering intensity is caused by the densification of the network polymers.
In the present work, 3D flowerlike CuS nanostructures were synthesized via a facile hydrothermal process using Cu2O hollow microspheres as templates. Reaction of Cu2O hollow microspheres with thioacetamide at 40 ℃ for 2 h followed by hydrothermal treatment at 120 ℃ for 12 h resulted in high yield of 3D flowerlike structure with diameters ranging from 200 to 300 nm. The Influence of experimental parameters on the morphology of the CuS nanostructures was investigated in detail. Different stages of the formation process were studied and thus the formation mechanism of the 3D flowerlike CuS nanostructures was presented.
A silica aerogel has been successfully synthesized using a short-chain ionic liquid, 1-butyl-3-methyl-imidazolium-tetrafluoroborate, as the solvent and tetraethyl orthosilicate (TEOS) as a precursor via an HCl-catalyzed sol-gel route. The molar ratio of ionic liquid to TEOS was controlled to be ca. 1.0. The sample drying proceeded through solvent extraction method with a vacuum to avoid the risky supercritical drying step. The prepared silica aerogel possessed a specific surface area of about 734 m2/g. Transmission electron microscopy and small-angle X-ray scattering analyses revealed that the prepared silica aerogel exhibited an open mass-fractal silica framework formed by the aggregation of the individual spherical silica particles. A two-level unified scattering function was adopted to fit the SAXS data to quantify the sizes of the mass-fractal clusters and their constituent silica particles.
Two types of hydrogels composed of poly(ethylene glycol) (PEG) and poly(N-isopropyl acrylamide) (PNIPAm) were synthesized via γ-ray-induced gelation. One type gel was a solid binary hydrogel. Gelation of PEG aqueous solutions was performed by γ-irradiation and homogeneous PEG matrix gels impregnated with NIPAm was also irradiated with γ rays. The other type gel was a porous binary hydrogel. It was also synthesized by γ-irradiation to a porous PEG matrix gel impregnated with NIPAm. The porous matrix gel was made by mixing silica microparticles (ca. 1.0 μm in diameter) into a PEG aqueous solution before gelation and then chemically decomposing them after gelation. These hydrogels show different thermoresponsive behavior. The swelling ratio of both hydrogels is reduced when the temperature is raised from 12 to 40 °C. However, the swelling ratio of the porous binary hydrogels was smaller than that of the solid binary hydrogels. In the solid gel, the PNIPAm chains are uniformly distributed and therefore the contraction of PNIPAm chains causes the shrinkage of the whole gel. In contrast, the PNIPAm chains of the porous gel are more localized in the pore spaces of PEG matrix gels, and exert less influence on the volume change of the whole gel.
A cataract is a clouding of the lens in the eye that affects vision. The one of the cause of the cataracts may be due to the abnormal aggregation of protein in lens. We found that two specific aspartyl (Asp) residues in αA- and αB-crystallins, respectively and one specific Asp in βB2-crystallin, from human eye lenses invert to the D-β-isomers to high degree during aging. The appearance of D-β-Asp isomers in proteins can cause major changes in the corresponding 3-D structure. Therefore, the presence of these isomers may be one of the triggers for abnormal aggregation, leading to cataracts. In fact, αA-crystallin containing large amounts of D-β-Asp obtained from cataractous patients of ～ 80 years of age has been shown to undergo increased aggregation to form massive and heterogeneous aggregates. Moreover, its chaperon activity, which prevents aggregation and insolubilization of other lenticular proteins, is reduced by 40%. Here we describe three important aspects of our research: (i) a method for detecting D-β-Asp at specific sites in particular proteins, (ii) a likely spontaneous mechanism by which Asp residues in proteins invert and isomerize to the D-β-form, (iii) a discussion of factors that favor such a reaction.
The cupric-ion adsorption effects on the nano-scale structures of the ultraviolet (UV) light irradiated poly(acrylamide/sodium acrylate) gels have been investigated by the small angle X-ray scattering (SAXS) measurements. It has been revealed that, without the cupric ion adsorption, the UV-light irradiated PAAm/SA gels do not show any characteristic structures in the SAXS profiles while a distinct peak has been observed in each of the SAXS profiles of the Cu-adsorbed gels; the SAXS peak position and width become smaller with the UV-light irradiation period indicating the development of the chelating aggregation of the network polymers of which the interconnections are progressively cut off with the UV-light dosage.
In order to clarify the mechanism of frost damage for concrete materials, we investigated the state of water in a Low Heat Portland Cement (LHPC) mortar at temperatures between T = 282 K and 202 K, using quasi-elastic neutron scattering (QENS). Below the freezing point of water (i.e., T ＜ 273 K), a broad peak for supercooled water in the LHPC mortar was clearly observed on a QENS spectrum. In addition, the supercooled water index (SCWI), which is the ratio of the signal from the supercooled water (SCW) to the signal from the free water at 282 K (FW282K) (i.e., SCWI = SCW / FW282K), was estimated for each temperature in a freeze-thaw cycle. Consequently, it was found that there is a hysteresis in the SCWI(T) curve; the amount of the supercooled water in the freeze cycle was 1.2-1.4 times larger than that in the thaw cycle at the same temperature.
Vacancy interaction in crystalline Si wafer is studied by numerical simulation based on the Tight-Binding Molecular Dynamics (TBMD) method. We evaluate an effective interaction between vacancy pair in bulk and in a thin slab as model systems of a Si wafer. In the case of vacancy pair in bulk crystal, results reveal that there is an effective “capture radius” of the vacancies to form a divacancy at around 8Å at 300K and 13Å at 600K. Surface structure involving vacancies in Si slab undergoes a reconstruction accompanying dimer-rows in  direction initiated by the vacancies. The capture radius is also found to exist in the slab and binding energy of the divacancy has depth dependence due to the surface effect.
Titanium (Ti) thin films were produced using a high frequency magnetron sputtering method with a Ti powder material target, and the processing plasma was analyzed via an optical emission method. Atomic force microscopic images of the films prepared using Ti powder targets show nearly the same images as the film prepared using Ti bulk target. XRD and XPS measurements suggest that titanium oxide thin films can be prepared using Ti powder targets, and their properties depend on the substrate temperature and the argon and oxygen gas mixture. Mono-atomic neutral tungsten atoms and ions were identified by optical emission spectroscopy.
Decomposition characteristics of benzene, toluene and xylene in a DC corona discharge in an artificial air at atmospheric pressure are investigated. By-products from benzene, toluene and xylene are identified by infrared absorption spectroscopy, and the decomposition processes of those substances in the corona discharge are examined. It is found that CO2, CO, HCOOH and (CHO)2O are major products, and that C2H2, HCN and (CHO)2 are minor products from benzene, toluene and xylene. It is also found that a major product, CH3COOCHO, and minor products such as CH3COOH, CH3COOONO2, CH4, HCHO and CH3COCHO are produced only in the artificial air containing toluene and xylene. CO2 is found to be a gaseous end product from benzene, toluene and xylene, and CO, HCOOH, (CHO)2O and CH3COOCHO are major intermediate products, which tend to be decomposed in the corona discharge. This leads that benzene, toluene and xylene are chiefly converted to CO2 via CO, HCOOH, (CHO)2O and CH3COOCHO.
In this study, multi-walled carbon nanotubes and few-layer graphene sheets have successfully grown on Si and polyimide substrates at relatively low temperature of 230～260°C by the microwave-excited surface wave plasma technique. Graphite-encapsulated Ni nanoparticles have been used as the catalyst for growing CNMs in NH3/CH4 plasma. It has been found that bias voltage and nature of the substrate can greatly influence the CNMs structure.
The heat source properties of TIG arc strongly depend on composition of shielding gas. For example, since the arc column is constricted due to high specific heat, heat flux onto a base metal in case of CO2 TIG arc is higher than that of argon TIG arc. The heat source properties can be controlled also by current waveform. Pulsed TIG welding is suitable for back-bead welding and thin plate welding, because the heat flux onto the base metal can be controlled by adjusting peak / base current ratio and frequency. In this paper, numerical simulation result of the heat source properties of pulsed TIG arc for various shielding gas composition will be reported. As a result, it was found that the heat flux increased immediately after transition from base current to peak current because of the thermal pinch effect. Furthermore, in CO2, although the heat transport toward the anode by convective flow was seen, that in radial direction due to thermal conduction was smaller than that of argon because of influence of large specific heat.
Effects of N2/Ar gas flow rate ratio on the crystallinity of sputtered ZnO films fabricated via nitrogen mediated crystallization (NMC) have been clarified. Introduction of small amount of N2 (N2/Ar = 4/20.5 sccm) drastically improves the crystal orientation and enlarges grain size of the NMC-ZnO films, where FWHM of XRD patterns for 2θ-ω and ω scan of (002) plane are 0.17° and 2.6°, respectively. A further increase in N2/Ar flow rate ratio deteriorates the crystallinity, since excess N atoms in the films disarrange the crystal structure of ZnO. Furthermore, ZnO:Al (AZO) films with high crystallinity have been successfully fabricated by utilizing the NMC-ZnO films deposited at N2/Ar = 4/20.5 sccm as buffer layers. 100-nm-thick AZO films with a resistivity of 6.8×10-4 Ωcm and an optical transmittance higher than 80% in a wide wavelength range of 500 nm to 1500 nm has been obtained.
The nitrogen-atom endohedral fullerene (N@C60) with relatively higher purity [molar concentration ratio of N@C60 to pristine fullerene (C60)] has been synthesized by controlling plasma ion irradiation energy (Ei) and C60 behavior. We have examined the relationship between the synthesis purity of N@C60 and Ei which is controlled by changing the substrate bias voltages (Vsub) and gas pressure (PN2) during the plasma irradiation process. It has been clarified that there is an optimum condition of the nitrogen plasma for the high-purity synthesis of N@C60, which consists of the high-density nitrogen-molecular ions (N2+) with suitable Ei from 40 to 80 eV. In addition, control of C60 behavior contributes to an increase in the reaction between C60 and N2+ to form N@C60, resulting in the synthesis of N@C60 with the highest purity of 0.56 % in the world.
Zinc oxide (ZnO) film deposition using a plasma-assisted mist chemical vapor deposition (CVD) with an inductively-coupled plasma source has been performed. The effects of the plasma exposure on film properties have been investigated with substrate location as a parameter. With decreasing the distance from antenna to substrate, the X-ray diffraction (XRD) results showed evident peaks of ZnO(0002), indicating that highly c-axis oriented films formed at low substrate temperature below 200°C. These results exhibit that the direct irradiation of argon/oxygen mixture plasma has enough potential for the crystallization of ZnO films. The effects of the concentration of a precursor in solutions on ZnO film deposition have been investigated. With decreasing the concentration of a precursor in solutions, the grain size of the ZnO films was small and the distribution of grain size was narrow. These results indicate that the structure control of ZnO film surface is available due to the concentration of a precursor in solutions.
Supported NiO nanocluster was prepared by using Ni colloid. Alkoxide stabilized Ni nanocluster supported on SiO2 was oxidized by exposing to air at room temperature to produce NiO nanocluster. The cluster size of NiO was estimated by XAFS analysis. Supported NiO nanocluster thus prepared showed the catalytic activity for oxidative coupling of thiophenol, whereas the conventional impregnation NiO catalyst did not. Remarkable NiO cluster size dependency on activity for oxidative coupling of thiophenol was observed.
We report a novel approach for fabricating Au nanocrysltas/porous coorodination polymers (PCPs) heterostructured composite based on preferential self-assembly of frameworks on nanocrystal surface. This approach involves the synthesis of carboxylic acid-fucntionalized Au nanocrystals and preferential growth of frameworks consisting of Zn2+ ions and benzene-1,4-dicarboxylate (bdc) on nanocrystals. Here, the key is to use Au nanocrystals stabilized with mercaptoacetic acid molecules bearing carboxylic acid groups that have strong interaction between metal ions of PCP precursors. During solvothermal reaction for construction of PCP frameworks, Au nanocrystals can be act as scaffolds for self-assembly of framework component. This approach allows us to synthesize Au nanocrystals dispersed in PCP crystals and will be extended to other types of nanocompoiste such as metal oxides and semiconductors.
One-dimensional (1D) superstructures constructing of inorganic nanoparticles have unique and technologically important potential applications in the areas of nanoelectronics, plasmonics, and molecular sensors. Herein, we describe how nanoporous template and in situ synthetic process can be combined for the construction of composite nanowires consisting of silver nanoparticles dispersed in polymer matrices. We show that, by limiting the space where nanoparticles grow, the silver nanoparticles are encapsulated inward within the polymer nanowires. We also demonstrated that the composite microstructure could be controlled by varying the initial precursor structure, pore size of the template and temperature.
Wood powder, after chemical removal of lignin and hemicellulose, was mechanically disintegrated into cellulose nanofiber. Focused on piezoelectricity, polarized optics and other applications with isotropic media, we attempted two different modifications (cyanoethylation and cyanoethylated dihydroxypropylation) of the nanofiber surfaces to decrease interfibrillar hydrogen bonds to enable uniaxial elongation and isotropic film orientation. Synthesized surface cyanoethylated cellulose nanofiber has no glass transition near the room temperature and was difficult to elongate uniaxially. Cyanoethylated dihydroxypropylcellulose nanofiber was viscoelastic at the room temperature with a piezoelectric constant of d14=3.2 pm/V.
We have investigated the electrical and optical properties of p-i-n junction structures in which un-doped GaNAs/GaAs multiple quantum wells(MQWs) were sandwiched by p- and n-doped GaAs layers. The samples were formed on the GaAs(001) substrates by plasma assisted molecular beam epitaxy(RF-MBE) using modulated N radical beam method. We have prepared several samples for various GaNAs MQW structures. As the results of I-V characterizations, it is found that threshold voltages of the p-i-n junctions were lowered by insertion of the GaNAs/GaAs MQWs i-layers. The photovoltaic effects were also observed under 1SUN by solar simulator. The conversion efficiency was slightly improved by insertion of the GaNAs/GaAs MQWs, which was confirmed by photo current measurements.
The structure and magnetic properties are reported for Gd/Fe multilayers with periodic line patterns fabricated by alternating UHV evaporation combined with photolithography or interference lithography and liftoff. In cross-sectional TEM images, the Fe layers show a grain structure, while no contrast was observed in the Gd layers. Magnetic hysteresis measurements show that the coercive field increases with line periodicity and magnetic layer thickness. This behavior might be attributed to not only the demagnetization field, but also the pinning effects of the crystal grain boundaries on the domain walls, and/or the influence of exchange coupling at the interface between Fe and Gd layers.
The self-spreading behavior of DMPC bilayer containing TR-DHPE molecule was observed in the presence of channel-type nano-architecture (nano-channel). The concentration of TR-DHPE at the spreading edge region was gradually decreased by passing through the nano-channel. The filtering efficiency was increased by elongating the channel-length, which was explained by considering a formation of a local compressed state of the spreading bilayer in the elongated channel region. In addition to the channel length, the filtering effect was found to be tuned by the channel angle (entrance angle). These two dependencies are important for precise control of filtering efficiency and selectivity.
Vanadyl phthalocyanine (VOPc) and fullerene (C60) composite nanoparticle having the diameter in the range of 15-60 nm has been prepared by reprecipitation methods from N-methyl-2-pyrrolidone/water solvent. The fabricated composite nanoparticles were compared with its monocomponent nanoparticles. The nanoparticles were characterized by UV-vis absorption, X-ray diffraction (XRD) and TEM methods. The UV-vis absorption indicates the formation of nanoparticles in the suspension state. The particle size measurements indicate that the composite particles are tending to form smaller particles than its monocomponent particles maybe due to faster nucleation in suspension state. The photoelectrochemical studies of composite nanoparticles were investigated in comparison with those of C60 (n-type) and VOPc (p-type) and the studies reveals that composite nanoparticles exhibit higher photoanodic current and also it possess n/p junction-like behavior.
Electrochemical exfoliation method had been developed for producing nanometer-size single layer graphene. We herein reported a developed method about producing single layer graphene with an average size of about 510 nm2 from analysis of scanning tunneling microscopy (STM) measurements. The high resolution STM images also showed clear carbon lattice structure of the produced graphene in an atomic level, indicating that our produced nano meter size graphene is not distorted and oxidized by exfoliation process and preserve pristine graphene lattice structure. Our developed technique provides a preparation of nanometer-size single layer graphene dispersed in a solution.
A high amount of publications about syntheses and application prospects for nanometer sized copper and the related oxide materials have been denoted during the last decades. This is most notably due to their amazing physical and chemical properties compared to the bulk material which result out of their high surface area to volume ratio. Particularly, their applicability in the new design of electronic and optical devices seems to be quite forward-looking. However, most of the application prospects require shapes with accurate dimensions and geometries. To meet the requirements, the preparation process by using ion track etched polycarbonate foils is very advantageous. Here, foils are irradiated with heavy ions in order to produce stochastically distributed tracks which are chemically etched to pores of desired diameters. Afterwards, the pores are filled with copper by either electrodeposition or chemical plating techniques. We investigated the availability of differently-shaped one-dimensional nanomaterials by applying diverse etch procedures in order to achieve symmetric and asymmetric pore cavities of the template. Furthermore, the availability of hierarchical cuprite structures by chemical treatment of produced wires is reported.
Polytetrafluoroethylene (PTFE) is used in various industrial applications because of its desirable physical and chemical properties. PTFE is chemically inert under most conditions, which means that there are few suitable microfabrication techniques available, and these are top-down processes. We report the fabrication of microstructures at desired spots on the PTFE surface using a 3 MeV focused proton microbeam with no patterning masks. The beam size on the surface was about 1 μm, and the surfaces were observed by scanning electron microscopy. When the 100-μm-thick PTFE sample was circularly scanned, the irradiated areas expanded and were raised above the original surface level. When the thickness of the PTFE was increased, the edge of the structure became rough. Spiral scanning from the center of the circle in the 500-μm-thick sample formed a 250-μm-tall cone. These microstructures were created by the volume expansion along the ion trajectories in the PTFE. The structures were formed through a bottom-up process and were dependent on the proton beam and the sample thickness.
We investigated the formation of track-etched membranes of poly(vinylidene fluoride) (PVDF), a type of fluoropolymer, in detail, using conductometry. A 25 μm-thick PVDF film was irradiated with a 450 MeV 129Xe or 2.2 GeV 197Au ion beam, and then the latent tracks were etched in a 9 mol dm-3 aqueous potassium hydroxide solution at 80ºC in a conductometric cell. This paper focuses on the theoretical basis of the conductometric method and the apparatus used in our study. Representative results are then given in terms of how the etching kinetics was affected by various experimental conditions including the irradiation parameters and cell voltages applied between the electrodes.
High hardness diamond-like carbon (DLC) films with good adhesion can be prepared by plasma source ion implantation in combination with radio frequency glow discharge plasma. Acetylene gas was used as the source gas to deposit the DLC films. Either pulses of -18 kV with a repetition rate of 1 kHz or DC voltages from -0.5 to -3 kV were applied to the substrate holder. A radio frequency (RF) of 13.56 MHz was applied to a counter electrode to generate a glow discharge plasma. The films were deposited on austenitic type stainless steel SUS304 as well as silicon wafers and characterized regarding thickness and surface morphology by cross-sectional SEM and by AFM, respectively. The chemical structure was investigated by Raman spectroscopy. The hardness of the films was evaluated by an indentation method. Furthermore, a ball-on-disc test was employed to obtain information about the frictional properties and sliding wear resistance of the films. The deposition rates of the films were enhanced by the RF discharge. The ID/IG value varied, depending on the deposition condition, in the range of 0.49 to 2.0. The hardness of the DLC films was around 19 GPa for the film deposited without RF and up to 26 GPa for the films deposited with RF discharge. A low friction coefficient was derived for all films prepared in this study, with lowest values of 0.04.
In this study, the high density diamond-like carbon (HD-DLC) with hydrogen-free was developed using filtered-arc-deposition (FAD) system. Mechanical properties of HD-DLC were evaluated. Relationship between film density and the adhesive strength from scratch test was discussed. It was found that the hardness is 80–90 GPa, the wear coefficient of HD-DLC is 0.1. The amount of losses of energy decreased at about 50%. Obtained the value of density of HD-DLC film is 3.4 g/cm3, which is 1.5 times than conventional DLC films. Furthermore, the adhesion strength of HD-DLC improved with increase of film density under bias voltage.
New microprocessing method with a combination of Proton Beam Writing (PBW) and Single Particle Nanofabrication Technique (SPNT) was demonstrated to control a location and a shape on cohering epoxy nanowires. The feature of this method is to utilize a flame structure which is able to rectify the solvent flow at the development and drying. At first, flame array with a rectification for solvent flows were fabricated by the PBW using SU-8 photoresist films. And next, long nanowires with the length over 50 μm were obliquely formed on these flames by heavy beam with the energy of hundreds MeV. In the case of the overwriting on the passage-type flame, concave structures which consist of the nanowires were formed with matrix array. On the other hand, convex structures were formed among the each cavity-type flame. It was shown that the polymer nanowires were can be controlled the cohering shape and the fixing at designed locations by the flames to rectify the solvent flow.
We are developing the Ion Photon Emission Microscopy (IPEM) system at JAEA. To observe a map by IPEM, the position where an ion strikes a scintillator placed over a microelectronics circuit is recorded together with the ion induced event. Since the spatial resolution is determined by the spot size of the Ion Beam Induced Luminescence (IBIL), the scintillator is one of the most important parts of IPEM. In this study we propose that a diamond containing a high concentration of Nitrogen Vacancy (NV) centers can be used as a scintillator with high spatial resolution. For both Y3Al5O12:Ce (YAG:Ce) and the diamond containing NV centers, the minimum spot size is a few micrometers. The IBIL intensity from the diamond containing NV centers is higher than that from YAG:Ce. According to these results, we suggest that a diamond containing NV centers is a rival candidate of a YAG:Ce from the point of view of single ion detection with high spatial resolution.
A couple of ion-induced processes are applied to fabricate a highly crystalline film of semiconducting silicide, β-FeSi2 on a Si substrate. One is the sputter deposition process, in which 35 keV Ar+ ions are utilized to deposit sputtered iron (Fe) on Si substrate to form β-FeSi2 in the temperature range around 973 K by means of ion beam sputter deposition (IBSD) method. The other is the sputter etching (SE) of the substrate surface prior to deposition, which plays a critical role in determining the crystalline properties of β-FeSi2 films. Authors have shown that when the SE conditions are properly chosen, continuous and relatively homogeneous β-FeSi2 thin films with high crystal orientation are fabricated with IBSD method in the temperature range of 873-973 K, with the film thickness of 50-100 nm. In addition, the interface is fairly smooth, where the transition layer at the interface is limited to a few atomic layers. Although care was taken to minimize the defect concentration in the obtained films, even the most highly-oriented β-FeSi2 films contain a small amount of defects. To make the defect concentration as low as possible, SE treatment was performed at lower incident energies. It was found that for Ne+ ions the incident energy could be lowered to 0.8 keV to obtain highly-oriented β-FeSi2 films.
Polytetrafluoroethylene (PTFE) felt is one of the medical materials used for brain surgery and cardiovascular surgery, such as reinforcement of the suture part, prosthesis of the defect part after the excision. However there are many problems due to its poor adhesion to around tissue. This study concerns fabrication of new cell adhesive materials by ion irradiation into PTFE felt. PTFE felt was irradiated with He+- and Kr+ -beams at fluences of 1×1014, 5×1014, and 1×1015 ions/cm2 at an energy of 150 keV. Surface characterization was performed by SEM, X-ray photoelectron Spectroscopy (XPS), and contact angle measurement. L929 mouse fibroblast cells were cultured on ion-irradiated specimen as cell attachment study. XPS measurement shows CF2 bonds were destroyed and C-C and C=C bonds were generated. From the results of cell cultivation, cell attachment to the ion-irradiated felt was dramatically improved as compared with non-irradiated PTFE felt. In our experiment, Kr+ beam irradiated PTFE felt at a fluence of 5×1014 ions/cm2 showed the most excellent cell attachment. Animal study demonstrated that tissue invasion was dramatically enhanced by ion-beam irradiation. These results indicated the possibility of ion-beam irradiated PTFE felt for clinical application.
The interdigitated electrode (IDE), that has a series of parallel micro-band electrodes with alternating micro-bands connected together, was utilized in electrochemical impedance spectroscopy (EIS) to build non-labeled human immunoglobulin A (IgA) immunosensor. Anti-human IgA was employed as a molecular receptor being covalently immobilized on the IDE through a self-assembled monolayer. EIS results exhibited that the adsorption induced by the antigen-antibody reaction between IgA and anti-IgA made an increase in resistance of the interfacial electron transfer (Rct). A linear relationship between the ΔRct and the logarithm of IgA concentration was confirmed for the IgA concentration range of 0.1 - 100 ng/mL. No modulation of Rct was detected by immersing in the solution of other proteins such as human immunoglobulin G, which indicates a high selectivity of this sensor for IgA. The surface images of sensor before and after the IgA binding were observed by atomic force microscopy.
Alkanethiol (CH3(CH2)n−1SH) has been used for study on molecular devices by academic and industrial research fields. This is because with it a high density self-assembled monolayer (SAM) can be easily formed on gold surfaces. In this work, we employed metallic conducting Langmuir-Blodgett (LB) films composed of BEDO-TTF and stearic acid as a soft electrode onto the alkanethiol SAMs (C12-SAM and C16-SAM) in order to prepare a tunneling junction in a large size (≈0.2 mm2). We found that the edges of base Au electrodes induced defects in SAMs and caused a current leakage. The substrates with SiO2 covering layer at Au edge increased the yield rate of device fabrication. The current density – voltage (J-V) characteristics across the junctions exhibited a nonlinear behavior, which suggested that tunneling is the dominant conduction mechanism.
We prepare two layers organic light-emitting diodes (OLED) composed of small molecular materials. Organic multilayers are accumulated by spin-coat method on polyethylene terephthalate/indium-tin oxide (PET/ITO) substrate. The multilayer is investigated by measurement of current density as a function of applied voltage at three different positions. Among these points, at the one farthest from the rotating center in the spin-coat process, the largest current density of 1.1 mA/cm2 is observed under a bias voltage of 20 V. For this point linear relationship in lnJ versus V1/2 and lnJ/V versus V1/2 indicate that the electronic conduction originates from Schottky and a hopping mechanism of carriers. At the other positions, where film thickness is thinner, tunneling current is expected.
We have investigated thermoelectric and transport properties of V, Sr and Mn substituted Sr2FeMoO6 systems. In the Sr2FeMo1-xVxO6, the bulk density increased with increasing V ion. For Sr2-yBayFeMo0.8V0.2O6, bulk density increased with the amount of Ba ions from the high density due to V substitution. The conductivity σ increased up to y=0.6 rapidly. In Sr1.4Ba0.6Fe1-zMnzMo0.8V0.2O6 samples, the Seebeck coefficient increased with increasing Mn substitution. As a result, the power factor, S2σ, of the Sr1.4Ba0.6Fe0.8Mn0.2Mo0.8V0.2O6 gave the largest value of PF=83.2 μW/K2m at 700ºC.
We have investigated the synthesis conditions, and the magnetic properties of M-type ferromagnetic potassium, lanthanum-iron oxides. The samples were prepared by solid-state-reaction. It is found that a new M-type ferrite can be effectively synthesized at 1275°C from the starting materials pulverized with a planetary ball mill. The magnetic transition temperature of the sample is 440°C which is quite close to that of the magnetoplumbite-type ferrite. EPMA compositional analysis for this new M-type ferrite shows the composition ratio of K : La : Fe = 0.75 : 0.90 : 18.58. From this result, the chemical formula of the magnetoplumbite phase in this sample is estimated to be K0.45La0.55Fe12O19-δ.
(1-x)BaTiO3-xFe3O4 composites were successfully prepared by conventional solid-state sintering of raw materials (BaCO3, TiO2, and Fe3O4) in the molar fraction x of Fe3O4 to BaTiO3 at 1323 K for 5 hours under Ar gas flow. X-ray diffraction (XRD) and electron probe micro analysis (EPMA) measurements were performed for these samples and it is confirmed that the composites consist of only two phases of BaTiO3 and Fe3O4. The largest saturation magnetization (Ms) of 73.4 emu/g was observed at x = 0.80, which was consistent with the product of the molar fraction of Fe3O4 and the Ms of pure Fe3O4. The largest MR ratio of 4.9% were observed under magnetic field of |H|>6 kOe for the x = 0.75 sample. The MR ratio is quadruple as large as that of Fe3O4. This result suggests that the formation of insulating BaTiO3 barriers and tunneling conduction of spins between Fe3O4-grains cause the large MR ratio in BaTiO3/Fe3O4 granular system.
We investigated molecular arrangement of organo-modified aluminosilicate with high surface coverage in Langmuir-Blodgett (LB) films by performing out-of-plane and in-plane X-ray diffraction (XRD) measurements. In addition, the surface morphology of mixed monolayers of organo-modified aluminosilicate and several biodegradable polymers [e.g poly(L-lactide), PLLA] was also characterized by atomic force microscopy (AFM). The in-plane XRD results of multilayers of organo-modified aluminosilicate formed by the LB method indicate the formation of a two-dimensional lattice of hydrocarbons on the aluminosilicate surface. These hydrocarbons of organo-modified reagents packed hexagonal in films. Based on our experimental findings, the LB technique enabled the formation of a densely packed organo-modified aluminosilicate monolayer at the water surface. Furthermore, for mixed monolayer systems comparising an organo-modified clay with high surface coverage and biodegradable polymers, a miscible surface was observed by AFM on a mesoscopic scales, whereas those with low surface coverage formed phase-separated structures.
We have newly constructed “multi-particle layered organization” of aromatic polyamide(poly-(N-alkylated benzamide), abbrev. PABAn, n : carbon number of side-chains) derivatives having both a rigid main chain and a flexible side chains by a Langmuir-Blodgett (LB) technique. This organization is composed of the build-up particle layers with highly regular arrangement along the c-axis. The particle arrangement of this organization of polymer nanosphere was estimated by performing out-of plane X-ray diffraction (XRD), and atomic force microscopic (AFM) observation. In addition, it is also proposed that ternary comb copolymers with carbazole units and both hydrogenated and fluorinated side-chains are candidates of newly typed “polymer nanosheet” material. These copolymers with high hydrophobic carbazole contents also formed single particle layer at air/water interface and “multi-particle layered organization” was constructed by a LB technique. Therefore, it was found that “multi-particle layered organization of polymer nanosphere” and “polymer nanosheet” are simultaneously formed by same component copolymer materials with hydrophobic carbazole units.
Adsorption behavior of DNA molecules to comb copolymers containing 2-vinyl-4, 6-diamino-1, 3, 5-triazine (VDAT) at air/water interface and their molecular arrangement have investigated by surface pressure-area (π-A) isotherm, IR spectroscopy, polarized UV-vis spectroscopy, and atomic force microscopy. A newly hydrogenated and fluorinated binary comb copolymers containing VDAT as adsorption template was synthesized by radical copolymerization. From the result of π-A isotherm of monolayer on DNA aqueous solution, an increase of value for molecular area per VDAT unit corresponds to 20 Å2. The IR spectrum of transferred LB multilayer indicates adsorption of DNA molecules by hydrogen bonding to the copolymer templates. AFM images show the circular domain at 50-60 nm diameters. Adsorbed DNA molecules showed the absorption band at 260 nm and emitted fluorescence at 400 nm. From the results of polarized UV-vis spectroscopy, these absorption bands indicate faint polarized dependency. In addition, emission bands in fluorescence spectrum of adsorbed DNA to copolymer film showed red-shift and became sharper than the one of their solution.
Transition behavior from a monolayer on the water surface to a single particle layer of a ternary comb copolymer containing carbazole rings have been investigated by surface pressure-area isotherm, atomic force microscopy, X-ray diffraction. This polymer monolayer is able to form the “polymer nanosheet” with amorphous layers and strong interaction between main-chains prepared by the Langmuir-Blodgett (LB) technique. Further, the single particle layer is able to form the multi-particle layered organization of “polymer nanosphere” by the LB technique. This ternary comb copolymers were synthesized by radical copolymerization with hydrogenated and fluorinated long-chain vinyl compounds. Poly(N-vinylcarbazole) homopolymer formed a single particle layer on the water surface immediately after spreading. Spontaneous “particulation” behavior is accelerated by incorporation of carbazole units in ternary copolymer films. Organized molecular film of these copolymers formed a monolayer on the water surface below 10 m Nm–1, and the monolayer were transformed to a single particle layer above 15 m Nm–1. Further, “polymer nanosphere” of these ternary comb copolymers showed an absorption band around 230 nm and emitted fluorescence at 390 nm. The emitted band in fluorescence spectrum of “polymer nanosphere” was red-shifted with respect to the one in the solution.
We synthesized new aromatic polyamides (poly-(N-alkylated benzamides), abbrev. PABAn) having both a rigid main chain and a flexible side chain with different lengths. We investigated the solid-state structures, that is, the molecular orientation and surface morphology, of organized molecular films of PABAn by performing surface pressure-area (π-A) isotherm, and atomic force microscopy (AFM) measurements. The solid-state structure of poly-(N-methyl benzamide) (PABA1) belonged to the monoclinic system, whereas PABA3, PABA4, and PABA5 showed an orthorhombic packing pattern. PABA7 and PABA8 formed amorphous polymers. In the case of PABA17, a two-dimensional hexagonal lattice was formed as a subcell consisting of side chains. These polymer monolayers were highly condensed on a water surface at 15 °C. At the air/water interface, changes in "particulation” behavior are confirmed in the system of PABA3 controlled molecular weight distribution. Monomolecular layer of PABA16 with narrow molecular weight distribution forms the large circular domain whereas existence of many angular domains for monolayer of PABA16 with broad one.
Formation and structure of organo-modified zirconium dioxides of multi-particle layered organization were investigated by out-of plane and in-plane X-ray diffraction (XRD) and atomic force microscopy (AFM). The surface modification of zirconia particle was performed by several long-chain carboxylic acids with different lengths. Langmuir monolayers of these particles were extremely condensed on the water surface. Multi-particle layered organization was constructed by the Langmuir-Blodgett (LB) technique. From the results of out-of plane XRD measurement of the multilayers of oleic acid-modified ZrO2 particles, a sharp peak was clearly observed at 52 Å. AFM image at mesoscopic scales of this single particle layer show particle assembly at 50 nm diameters. However, fine particles at about 5 nm diameters are confirmed in the case of high-resolution AFM observation to the mono-particle films transferred at low surface pressure region. Therefore, it is found that regular periodic structure along the c-axis and a hierarchical aggregated particle form were fabricated by Langmuir and LB technique.
Stretchable and highly conductive films made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) were prepared by casting the PEDOT/PSS aqueous dispersion as colloidal gel particles containing xylitol and subsequent heating. The electrical conductivity and elongation at break of the PEDOT/PSS film containing 50 wt% of xylitol significantly increased from 0.46 S/cm to 114 S/cm and from 4% to 33%, respectively, by heating at 140 °C in air for 1 h. It was found that the xylitol had two functions as (i) plasticizer preventing hydrogen bonding and (ii) secondary dopant increasing the mobility of charge carriers between the colloidal particles.
Poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) was synthesized by oxidative polymerization and pH dependence of structure and electrical conductivity of the cast films were investigated by means of UV-vis-NIR, XRD, AFM analyses, and four-point technique. It was found that the neutralization of PEDOT/PSS with NaOH decreased the absorption of bipolarons representing the PEDOT in the highly doped state and disrupted the π-π stacking of the PEDOT crystalline structure, which lowered the electrical conductivity by six orders of magnitude with increasing the pH from 1.7 to 13.