The development of high-dielectric constant thin film materials is essential for future active and passive nanoelectronics devices. Recently we developed high-dielectric constant thin film materials for thin film capacitor and gate dielectrics by combinatorial technique. Combinatorial thin-film of (1-x)[BaTiO₃]-x[Bi(Mg_2/3Nb_1/3)O₃]– (BT-BMN) was grown on Pt/SiO₂/Si, using pulse laser deposition (PLD) method, by deviating from stoichiometry and Bi-10 wt% enriched targets to optimize the Bi content. X-ray photoelectron spectroscopy analysis revealed a linear Bi composition spread. As-deposited films post-annealed at high-temperatures under oxygen atmospheres turned into crystalline state and the crystallinity, characterized by the full width at half maximum of x-ray diffraction, is better towards Bi-enriched end. The dielectric constant showed a strong dependency of Bi composition and it increased with the increase of Bi and saturated over 7 wt% Bi. The scanning nonlinear dielectric microscopic investigation revealed that ferroelectric phase distribution is better around Bi-7 wt% region where the measured leakage current is also minimum. This tendency suggests that nonstoichiometric Bi concentration in the PLD target influences the thin-film electrical properties. Dielectric constant over 300 and dielectric constant stability below 10% from 25 to 400 °C were obtained.

The Titanium Dioxide nanoparticles (TiO₂ NPs) with desired ratio of anatase and rutile have been prepared by convenient and operable green method using Peltophorum pterocarpum (PP) flower extract. The prepared TiO₂ NPs have been characterized by X-Ray diffractometer (XRD), Transmission Electron Microscope (TEM) and Raman spectroscopy. The XRD exhibits that the prepared TiO₂ NPs were crystalline with various percentage of anatase and rutile phases. The TEM images show that the prepared nanoparticles are nanometre in scale. The influences of annealing temperature on structural properties have been investigated for 100% anatase TiO₂. A clear evidence of structural transformation from pure anatase to anatase–rutile mixed phase structures has been confirmed by XRD. In this study, it was found that, the TiO₂ NPs can be prepare with desired ratio of anatase and rutile with high uniformity, high surface area and minimum aggregation by controlling the experimental conditions such as dosage of flower extract. It exhibit excellent antibacterial activity against Escherichia coli and concludes that the higher amount of anatase shows higher activity.

Mg and the alloys are materials with highly anisotropic and an extruded Mg₉₆Zn₂Y₂ alloy used in this study also has strong anisotropy. One of the factors originates in LPSO phases extending along the extrusion direction which the Mg₉₆Zn₂Y₂ alloys have. In this study, a change of the LPSO phases morphology during ultrasonic spot welding process was evaluated, and the relationship between the microstructure evolution and crack propagation after the lap shear tensile test was discussed. Ultrasonic vibration was applied in a direction orthogonal to the LPSO phases extending along the extrusion direction and was applied in a direction parallel to the weld interface of specimens. As a result, the LPSO phases orthogonal to the vibration direction formed curved LPSO phases and rearranged in the direction parallel to the weld interface during the welding process. And, it was revealed that the rearranged LPSO phases extended in the radial direction of the spot welds. The severe plastic deformation during the welding process effected a drastic change of the LPSO phases. In addition, plug fracture was exhibited in the region where the severe plastic deformation occurred.

Aiming to reduce simulation times and to incorporate track potential into the conventional Monte Carlo simulation code, an examination of whether simple formulas can be used as the track potential is conducted. Here, the track potential is defined as a potential formed from the electric field near the track of the heavy ion. The motion of secondary electrons is simulated to obtain the probability of energy flow escaping the track potential and the radial dose.

In recent years, three-dimensional scaffolds have attracted great attention due to the development of stem cell tissue engineering. It is expected that the combination of three-dimensional scaffolds and stem cells will be a promising therapy for large defects of tissue such as bone. We have been developing three-dimensional scaffolds by coating poly-lactic acid (PLA) nanofibers with hydroxyapatite (HAp; Ca₁₀(PO₄)₆(OH)₂). Although PLA, a biodegradable polymer, is used in many biomaterials and HAp has great biocompatibility, PLA nanofibers are difficult to coat with HAp due to its hydrophobic property. Calcium phosphate deposition requires hydrophilic groups such as carboxyl groups, which play a key role as calcium phosphate nucleation sites. Hence, in this work, the surface of PLA nanofibers was modified by vacuum ultraviolet (VUV) irradiation or by co-electrospinning with gelatin as a hydrophilic polymer to increase the number of calcium phosphate nucleation sites. The deposition behavior of calcium phosphate on the VUV irradiated PLA nanofibers was facilitated in comparison with the pristine nanofibrous PLA matrices. Therefore, the surface modification via VUV irradiation was an effective way to produce nucleation sites for calcium phosphate deposition.

  Five types of diamond-like carbon (DLC) films {DC pulse CVD (Benzene), RFCVD (Butylbenzene), Ionization (Benzene), HiPIMS (Carbon), RFCVD (Pyrrole)} with different sources and methods were deposited on Si substrate. Oxygen plasma treatment by RF Capacitively Coupled Plasma was uniformly applied to these DLC films. The film thickness linearly decreased with plasma treatment time. In all substrates, the C═O rate of the film surface was increased by the oxygen plasma treatment for 0.5 minutes, and the C═O rate was constant for further treatment time. Moreover, the full width at half maximum (FWFM) of the XPS Carbon 1s (C_1s) spectra of the DLC film deposited by hydrocarbon gas was constant to the depth direction. However, in the any DLC films, the FWHM of XPS C_1s spectra was greatly changed in the surface layer and the middle layer of the DLC film. Therefore, it was suggested that in the DLC films using a hydrocarbon gas (Benzene, Butylbenzene) as a material, the FWHM are constant. On the other hand, in the HiPIMS using carbon as a material, the FWHM increased in the middle part of the film. In RFCVD using pyrrole as a material, the FWHM at the surface layer increased. It was suggested that the structure was different between the film surface layer and the middle layer depending on the film deposition method and materials.

Novel diamine monomers containing imidazolium or pyridinium groups were synthesized to prepare ionic polyimides, which were expected to have the affinity with CO₂ gases. Then, the nanosheets of these polyimides, the thickness of which were 50 - 90 nm, were fabricated by spin coating method. Furthermore, the nanosheet-coating of polydimethylsiloxane graft copolyimide membranes was carried out, and the effect of surface structure on the gas permselectivity was investigated. As a result, the nanosheet coating on the highly gas permeable membrane was effective to improve the selectivity of CO₂/N₂ and O₂/N₂ with maintaining the high gas permeability to some extent. In addition, it was found that the gas separation properties depended on the side chain structures of polyimides containing ionic groups.

We studied the formation of gold nanoparticles (Au NPs) by laser-induced nucleation from HAuCl₄ in viscous glycerin (η = 1,400 mPa s) at a room temperature for the application of laser-drilled screen printing. Femtosecond pulsed laser irradiation at a wavelength of 800 nm and a pulse energy of 5 mJ caused Au NPs with a mean diameter of 4.9 nm at a concentration of 2.5×10^-5 mol dm^-3. The decrease in viscosity by heating the solution at 313 K and the mechanical stirring of the solution during laser irradiation caused the mean diameter and size distribution to become small. The mechanical stirring was effective for the formation of uniform Au NPs with a mean diameter of 3.2 nm. These indicated that successive pulsed laser irradiation induced uniform nucleation reactions of HAuCl₄ to metal Au, melting and fusion among metal Au species, and particle growth through Ostwald ripening. The Au NPs formed in glycerin kept a suspension for at least 1 week without any stabilizing surfactants probably due to low frequency of contacting NPs in viscous glycerin.

Laser drilling of engineering plastic films was performed using a picosecond pulsed laser at different repetition rates for the application of through-hole membranes to laser-drilled screen printing. Four engineering plastic films of polyimide (PI), poly(ethylene terephthalate) (PET), poly(phenylene sulfide) (PPS), and poly(ether ether ketone) (PEEK) were investigated. Frustum-shaped through holes were formed with high reproducibility by laser drilling at a repetition rate of 10 kHz. Higher repetition rates induced the formation of heat affected zone around the edge of the thorough holes in the case of engineering plastic films with their low melting point. The mean diameters of through holes formed on the film surfaces of both laser entry and exit sides at the identical repetition rate increased in the order of PEEK ≈ PET < PI < PPS, which had a relationship with the optical absorption properties at the wavelength of the laser pulses. It was suggested that the PI film was appropriate to a laser-drilled through-hole membrane in terms of the shape of through holes in addition to its chemical and thermal stabilities.

  Effect of plasma sterilization for bacillus subtilis var. natto was studied using pulsed laser ablation and low pressure RF plasma, which usually used for functional thin film deposition. In addition, bulk and powder were used as the targets and compared the effect for the sterilization. Experimental results suggest that bacillus subtilis var. natto was not sterilized in the only vacuum state. However, they can be sterilized using low pressure RF plasma and pulsed laser ablation plasma irradiation. The effect of the sterilization using powder target was higher than that of bulk target, and that of the pulsed laser ablation plasma was higher than RF plasma. Those results suggest that the effect of sterilization was decided by the density of the high-energy metal atoms and ions.

  The relationships of adsorption abilities of cesium and strontium in the presence or absence of oxygen in the atmosphere during carbonization of rice hull charcoal was investigated. Rice hulls were carbonized at 400–1000 °C by flowing nitrogen gas containing 100% nitrogen or 3% oxygen. The amount of acidic functional groups was higher with 3% oxygen. The rice hull charcoal carbonized in any atmosphere decreased the amount of acidic functional groups with increase in carbonization temperature. A correlation was found between cesium adsorption rate and acidic functional group content. However, there was no correlation between strontium adsorption rate and acidic functional group content. The specific surface area was largest at 237 cm²/g at 800 °C for charcoal carbonized with 3% oxygen and largest at 124 cm²/g at 600 °C for charcoal carbonized with 0% oxygen. From the measurement results of pore distributions, it was found that the volumes of mesopores were larger in charcoal carbonized in 3% oxygen atmosphere than that carbonized under 0% oxygen. There was a high correlation between the pore volume of mesopores and the adsorption amount of strontium. It seemed that rice hull charcoal carbonized with 3% oxygen had a large adsorption rate of strontium.

Self-assembled monolayers (SAMs) of amphiphilic organic molecules that form on a solid surface have generated an enormous amount of interest in interdisciplinary research areas as diverse as molecular engineering of surfaces, tribology, biology, nanotechnology, polymer composites, organic electronics, and analytical chemistry. We measured the contact angle to study the surface chemistry and structures of SAMs. Octadecylphosphonic acid (OPA) has the featureof being able to form a monomolecular film in an extremely short time (i.e., within several seconds). The analytical approaches developed in this study should be applicable to research and development related to controlling surface properties.

The optical and electronic transport properties of bismuth telluride (Bi₂Te₃) nanoplates were determined using infrared spectroscopy measurements combined with first-principles calculations. The Bi₂Te₃ nanoplates were prepared by solvothermal synthesis and consisted of single-crystalline particles of hexagonal shape, with edge lengths of approximately 1.2 μm and a thickness of less than 30 nm. To determine the optical and electronic transport properties, the nanoplates were aligned on a glass substrate by using a drop-casting method. We prepared two types of nanoplates: a non-annealed sample with high resistance (due to the presence of isolated nanoplates) and an annealed sample with relatively low resistance, due to its connected nanoplates. The bandgap of the nanoplates, evaluated using infrared spectroscopy, was not significantly affected by the connecting process. The direct and indirect bandgaps were estimated to be approximately 0.14 and 0.06 eV, respectively, and were different from the values previously reported for single-crystalline bulk materials. Although the exact reason for this difference is not clear, we suggest that the structure of the nanoplates might influence the electronic band structure. The electronic transport properties were estimated by infrared spectroscopy using the Drude model, with the effective mass determined from the band structure obtained from first-principles calculations based on density functional theory. The electronic transport properties of the non-annealed nanoplates were essentially the same as those of their annealed counterparts. Therefore, we conclude that the electronic transport properties of nanoplates can be estimated through a combined analysis of different samples, in which the nanoplates are tightly connected or isolated from each other.

Syntheses of 3-(N,N-dimethylamino)tryptanthrin (T3NMe₂) and 9-(N,N-dimethylamino) tryptanthrin (T9NMe₂) were performed, and their absorption and fluorescence properties were evaluated. T3NMe₂ and T9NMe₂ were both expected to undergo intramolecular charge transfer (ICT) between their conjugated electron-donating amino groups and electron-withdrawing carbonyl groups as did the previously reported 2-(N,N-dimethylamino) tryptanthrin (T2NMe₂). However, the characteristic fluorescence solvatochromism resulting from ICT was not observed in T3NMe₂. Density functional theory (DFT) calculations indicated that the highest occupied molecular orbitals (HOMOs) of both T2NMe₂ and T9NMe₂ were localized on the amino group side, while the lowest unoccupied molecular orbitals (LUMOs) were localized on the side of the conjugated carbonyl group. However, the HOMO of T3NMe₂ was localized on the amino group side, while its LUMO was localized on the unconjugated carbonyl group side. It was thus concluded that only T3NMe₂ exhibited no ICT behavior.