The effect of irradiating EMIM+ or N(CN)2- ion beams by using an ionic liquid ion source was discussed for application to metal-free negative-ion focused ion beams. We found that N(CN)2- ion beams exhibit substrate etching under an acceleration voltage greater than 1 kV. Especially, N(CN)2- irradiation at 4 kV yields large etching depth in Si substrates, as estimated by a Si/N(CN)2- sputtering yield of 10.0, and causes surface smoothing due to chemical etching, which was indicated by a decrease in the surface roughness of Si from 0.07 nm to 0.05 nm. In contrast, glass substrates were mainly etched with physical sputtering by incident ion beams. Moreover, the results of XPS and spectrophotometer measurements revealed that the irradiation of N(CN)2- at 1 kV forms a carbon-nitride film including g-C3N4.
Dielectric elastomer is one of the new types electronic materials that have both drive ability and electric generating capacity. In this research, fundamental tests were performed to evaluate abilities of dielectric elastomer. As the result, it was found that dielectric elastomer had very efficient drive ability and electric generating capacity, and that it was applicable to both slow and high speed motions. This means many effective applications are expected using this material. As one of the applications, dielectric elastomer was applied to remove piled snow on solar panels. Dielectric elastomer can generate slight-vibration, and the vibration decreases the frictional resistance between the surface of solar panels and piled snow. As the result of the test, it was found that snow removal by slight-vibration was very effective and that energy spent to remove snow using vibration was about 1/20 of melting.
It is important to investigate lattice defect structure in AlN crystal to improve the properties of AlN ceramics. Positron annihilation lifetime measurement (PAL) was carried out to investigate lattice defects in high thermal conductivity AlN ceramics. PAL measurement can detect atomic vacancy type defects like point defect in crystal with non-destruction and high sensitivity. Two positron lifetime components were observed at 230 and 132 ps, which were assigned to lifetime components of aluminum-site vacancy (VAl) and AlN perfect crystal, respectively. There was a good correlation between positron mean lifetime and thermal conductivity of AlN ceramics. Also, it was found that there was a good agreement between VAl concentration calculated from thermal conductivity and positron lifetime analysis. On the other hand, VAl concentration calculated from dissolved oxygen concentration in AlN grain was two orders higher. It was suggested that aluminum octahedrally coordinated to oxygen structure formed below 0.75 at% and they were not affect to phonon scattering.
The molecular environment of a living cell is totally different from that of a typical test tube solution; about 30% of the volume of the cell interior is occupied by large biomolecules, small metabolites, and osmolytes, leading to molecular crowding conditions. In particular, there are large amounts of zwitterionic molecules that act as osmolytes, and amino acids. Here, we studied the thermodynamics of the canonical DNA duplex and non-canonical DNA G-quadruplex structures under molecular crowding conditions using a phosphorylcholine derivative, 2-methacryloyloxyethyl phosphorylcholine (MPC), as a model compound of a naturally occurring zwitterionic molecule. It was found that MPC stabilized the DNA G-quadruplex structure, whereas it destabilized the DNA duplex.
The palladium-catalyzed coupling reaction between an aryl halide and a terminal alkyne, the so-called Sonogashira coupling reaction, was found to occur in water under copper-free conditions using an amphiphilic polystyrene–poly(ethylene glycol) (PS-PEG) resin-supported palladium–terpyridine complex, giving the corresponding aryl-substituted alkyne in high yield. The PS-PEG resin-supported palladium–terpyridine catalyst was recovered simply by filtering the product mixture under air and could be reused three times with only slightly decreased catalytic activity after each use.
A magnetic phthalocyanine based carbon material has been successfully synthesized by using a low energy process that employs highly chlorinated iron-phthalocyanine as building blocks and an alkali metal as a coupling reagent. The X-ray diffraction patterns and XPS spectrum for the reaction products suggest that they consist of amorphouscarbon material that contains uniformly dispersed iron ions. The iron phthalocyanine based carbon material exhibits ferromagnetic properties at room temperature and the ferromagnetic phase transition occurs at TC=490 K.
To prepare hydroxyapatite (Ca10(PO4)6(OH)2) thin films with a stoichiometric Ca/P ratio via pulsed laser deposition (PLD), the spot area of the laser pulse was changed independently of the laser fluence. To maintain a constant fluence when the spot area was changed, the total energy irradiated on the target surface was adjusted relative to the spot area. We found that the spot area dramatically changed the Ca/P ratio of the hydroxyapatite thin films that were prepared via PLD with a constant fluence. The best Ca/P ratio of 1.72 ± 0.13, which is close to the stoichiometric ratio (1.67), is achieved with a spot area and a fluence of 3.8 mm2 and 2.4 J/cm2, respectively. We report on the importance of the spot area in the PLD technique for the first time.
We developed the theory that the quasi particles is a degree of freedom of a spin magnetic moment, and rebuild the theory into a form suitable for control theory of spintronics. We tried to apply to devices using spin tunneling. Specifically, as the ferromagnetic tunnel junction with a pure spin current, from the analogy of the superconducting Josephson junction, we introduced a model of the ferromagnetic spin Josephson junction and have developed a theory to analyze it.
Three-dimensional encapsulation of a living human cervical cancer HeLa cell in a redox-active cytocompatible phospholipid polymer hydrogel and the regulation of cell functions with simple bioelectrical stimulation were investigated. A redox-active and cytocompatible polymer based on the water-soluble phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)-co-p-vinylphenylboronic acid (VPBA)-co-vinylferrocene (VFc)) (PMBVF) was synthesized by conventional radical polymerization method. A HeLa-Fucci cell, a human cervical cancer HeLa cell stably expressing fluorescent ubiquitination-based cell cycle indicator (Fucci) were cultured and suspended into the medium, in which a PMBVF polymer were pre-dissolved with desired concentration. Poly(vinyl alcohol) (PVA) solution was added to this PMBVF/HeLa-Fucci medium solution with gently mixing at room temperature, in which case, a reversible PMBVF/PVA hydrogel with encapsulated HeLa-Fucci cells was obtained. The morphologies of the PMBVF/PVA hydrogel and the three-dimensional encapsulated HeLa-Fucci cells were confirmed with microscopy. Cyclic voltammograms results indicated that PMBVF/PVA hydrogel still had excellent electrochemical properties even in the presence of living HeLa-Fucci cells. A constant voltage (0.4 V vs. Ag/AgCl) was applied to the extracellular environment of encapsulated cells as electrical stimulation and the cell cycle progression was calculated base on the analysis of fluorescent images. Compared with that without electrical stimulation, a delay of the cell cycle progression could be observed between 8 h and 18 h while the cells were encapsulated in the hydrogel with electrical stimulation. The investigation of cell functions based on a three-dimensional electrical stimulation with a redox-active cytocompatible phospholipid polymer hydrogel will promote the development of electrochemical therapy of cancer and tumor.
Hydrogen bonding configurations and hydrogen content of a-C:H films deposited by H-assisted plasma CVD were investigated by Fourier transform infrared spectroscopy. Plasma parameters related to deposition rate were derived using optical emission spectroscopy. The a-C:H films contain a large number of sp3 configurations (93%) and a few sp2 configurations (7%). Most of the hydrogen is bonded in methyl groups which shows the structure of deposited a-C:H films is polymer-like carbon. The mass density has nearly linear decreases with increasing the hydrogen atom density, indicating that control of hydrogen content is crucial to obtain a-C:H films of high mass density. A slight increase in radical generation rate and significant increases in etching rate by hydrogen atoms lead to decrease the deposition rate when the discharge voltage increases from 170 V to 180 V.
Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight-bearing surfaces in total joint arthroplasty. However, the wear phenomenon of UHMWPE in knee and hip prostheses after total joint arthroplasty is one of the major restriction factors on the longevity of these implants. In the microscopic surface observation of the virgin knee prosthesis, microscopic machining grooves caused by the machining process were observed on the surface of the UHMWPE tibial insert. The authors focused on the machining grooves as a factor influencing the wear mechanism of UHMWPE. The 3D microscopic surface profile measurement and reproduction of the surface of the UHMWPE tibial insert were performed to produce finite element models of the machining grooves based on actual measurement data. Elasto-plastic finite element contact analyses between UHMWPE microscopic surface model with machining grooves and the metallic femoral component were also performed to investigate the mechanical state and wear behavior of UHMWPE surface zone with the machining grooves. The analytical findings of this study suggest that the machining grooves of the UHMWPE tibial insert are one of the important factors influencing the microscopic failure and/or microscopic wear behavior of the UHMWPE tibial insert in the knee prosthesis after total knee replacement.
We compared experimental results of confocal Raman microscope and Time Domain Reflectometry (TDR) measurements using a coaxial electrode with a flat-end termination for water content distribution in the depth direction of the human skin. The TDR method suggests an average value of water contents in depth direction from the skin surface to a certain depth. On the other hand, the confocal Raman microscope offers a value of the water content at each depth of the skin. The difference between water contents thus obtained by the both methods was well described by the quadratic expression of the depth from the skin surface. The water content in the skin detected by the electric field from the coaxial electrode on the skin surface used in TDR method decays in proportion to the square of the depth from the contact surface. It is expected that TDR measurements with the flat-end electrode thus characterized in the present study make it possible to offer newer simple experimental techniques to evaluate human skin.
To modify the surface properties of segmented polyurethane (SPU), 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers were applied. We prepared different molecular architectures of the MPC polymers, that is, random-type, block-type, and graft-type to investigate durability of the MPC polymer layer on the SPU. The SPU membranes modified with the MPC polymers were characterized using X-ray photoelectron spectroscopy. The better stability was observed in the poly(MPC-graft-2-ethylhexyl methacrylate (EHMA))(gPMEH) polymer layer on the SPU membrane after immersion in an aqueous medium, the possible reason would be the intermiscibility of the poly(EHMA) segments and the soft segments in the SPU. Each SPU/MPC polymer membrane demonstrated a dramatic suppression of protein adsorption from human plasma. From these results, the antithrombogenicity of the 2.0 mm diameter SPU/gPMEH tubings was investigated. We concluded that the SPU membrane modified with the gPMEH was one of the promising polymeric biomaterials for making blood-contacting medical devices.
Our previous study showed that amorphous HfO2, ZrO2, TiO2, In2O3, Ga2O3, Al2O3, and Cu2O adopt dual-random-sphere-packing (Dual-RSP) structures. Since crystalline Li2O adopts a dual-crystalline-sphere-packing structure, namely the superposition of the simple cubic structure of lithium and the face-centered-cubic structure of oxygen, it is also expected that liquid and amorphous Li2O adopt Dual-RSP structures. In this paper, to verify this, we performed ab initio molecular dynamics simulations. Our results show that the Dual-RSP model is also applicable to liquid and amorphous Li2O.
Effects of pulsed laser ablation (PLA) plasma on sterilization were studied using a thin film deposition system. Yeast fungus and spore-forming bacteria were used as the subjects of sterilization, and Ag bulk was used as the PLA target in this experiment. Experimental results suggest that both yeast fungus and spore-forming bacteria can be sterilized using PLA plasma irradiation. The effectiveness of the sterilization strongly depended on the laser fluence and irradiation time. From the optical emission spectra, it was inferred that the main sterilization factors are high-energy Ag atoms and ions, and UV light, as well as shock waves.
Optical properties of Ga0.82In0.18N p-n homojunction light-emitting-diode are investigated by the photovoltaic, photoluminescence-excitation, electroluminescence (EL), and photoluminescence (PL) measurements. Although the X-ray diffraction measurements indicate a uniform InN molar fraction x in the sequentially grown n- and p-type Ga0.82In0.18N layers, the EL and PL exhibited different peak energies at room temperature. The difference is explained by the emission models in the n- and p-type of Ga0.82In0.18N layers. The results demonstrate a potential use of Ga1-xInxN p-n homojunction for further development of functional device structures.
New UV-stimuli-responsive liposomes composed of two different kinds of phosphates, dipalmitoylphosphatidylcholine (DPPC) and azobenzene (Az)-containing amphiphilic phosphates were fabricated. The release behavior of calcein within the phospholipid vesicle lumen was studied by monitoring the changes of fluorescence intensity. As the results found in this paper, the instability of the lipid bilayers were caused along with the defects in the membrane regions through photoisomerization of Az, which provided a channel or increase the permeation for calcein release. The effects of Az structure and incorporation ratio were studied, with the results showing that high incorporation ratio induced high activity of release behavior. Moreover, the liposomes made by the Az with a longer hydrophobic alkyl chain gave a stable construction.
We calculate systematically the atomic volume changes caused by Sc-Ge impurities in Al, using the formalism given by the Kanzaki model. All the parameters in the Kanzaki model, such as the Hellmann-Feynman (HF) forces and the lattice distortion, are calculated by the ab-initio calculations based on the generalized-gradient approximation in density functional formalism and the full-potential Korringa-Kohn-Rostoker (FPKKR) Green’s function method for point defects. Most of the calculated results agree very well (within the error of 5%) with the available experimental results. We found that the calculated results for the HF forces on the 1st-nearest neighboring host atoms around impurities are strongly correlated with the volume changes per impurity in Al. The magnetism of 3d transition-metal impurities (Cr, Mn, Fe) is also discussed.
Algorithms for determining the element-selective charge density are developed using two-wavelength anomalous synchrotron X-ray powder diffraction (MAPD) data. We have reported that an algorithm of element-selective charge density study from three wavelengths MAPD using near K absorption edge. The present study, we developed an algorithm from two wavelengths MAPD using near LIII absorption edge. The method is employed in order to investigate a large anharmonic thermal vibration of Gold atom in Gold metal complex, Au(tmdt)2 (tmdt: trimethylene- tetrathiafulvalene-dithiolate).
Hollow AZ31B magnesium alloy pipe of 30mm in outer diameter and 10mm in inner diameter was made by vertical continuous casting using semisolid slurry prepared on an inclined cooling plate. The pipe could not be formed using a mold and a core rod without taper for forming the hollow because of the strong resistance between the mold and the semisolid slurry during casting. However, it was possible to make the pipe using both a taper mold and a core rod. Even so, the pipe surface appeared corrugated because the residual resistance between the mold and semisolid slurry influenced the pipe drawing. However, healing phenomenon occurred near the mold and core rod with heaters so that the remelted slurry was covered with the surface cracks. The distribution of the solid fraction in semisolid slurry inside the mold was evaluated by calculation.
The amino acid sequence of vanillin-binding site of transient receptor potential vanilloid type 1 from rat, Leu544–Tyr553, was extracted and hybridized with His-tag. The hexadecamer invariant chain peptide, Leu-Ala-Met-Gly-Trp-Thr-Asn-Met-Leu-Tyr-His-His-His-His-His-His (VBH), was prepared by solid-phase peptide synthesis. Circular dichroic spectral measurements determined the α-helix content to be 17%, which was consistent to that of short peptides. In a combined use of thiol-derivatized nitrilotriacetic acid (s-NTA) monolayers, the His-tag successfully attached the whole peptide on gold substrate surfaces through Ni2+-chelation (ΓVBH = 224 ± 120 pmol cm-2, n = 8). Moreover, various surface analyses including atomic force microscopy imaging, FT-IR spectroscopy, and quartz-crystal microgravimetry (QCM) revealed self-assembly (SA) of VBH at the S-NTA monolayer surfaces. QCM measurements also showed that vanillin, the major component of natural vanilla flavoring, binds to VBH SAs (Kapp = 2.7 × 103 M–1). The affinity of host–guest binding remains limited but possesses a certain degree of selectivity; for cases of structural analogs that give a pleasant flavor, acetophenone showed rather weak affinity (Kapp = 2.8 × 102 M–1) whereas 4-heptanone did not bind at all. With these results VBH was concluded to be useful in vanillin sensing as a supramolecular affinity host.
In this work, we investigated the influence of the pH condition during the impregnation process on the immobilization of molybdosilicic acid on hollow silica spheres and their activity for hydrolytic dehydrogenation of ammonia borane. To adjust the pH, amino acids such as L-aspartic acid and L(+)-arginine were added to the impregnating solution. Transmission and scanning electron microscopy showed that samples prepared at lower pH consist of homogeneous hollow silica spheres while those prepared at higher pH include collapsed hollow spheres. The activity for hydrogen evolusion from aqueous NH3BH3 solution depends on the catalyst; the molar ratios of the hydrolytically generated hydrogen to the initial NH3BH3 were 2.0, 1.3, 1.3, and 1.0 at pH = 4.0, 6.0, 8.0, and 9.7, respectively. After the reaction, the sample prepared at lower pH had a higher valence value of Mo species according to results from X-ray photoelectron spectroscopy, and the corresponding amount of Mo species in the reaction solution was also lower. The results indicated that the molybdosilicic acid supported on homogeneous hollow silica spheres had a higher valence value of Mo species and the effectively immobilized acid had a higher activity for hydrogen evolusion from aqueous NH3BH3 solution.
Continuous zinc oxide (ZnO) films were formed on glass substrates by using a two-step method, including seed layer formation by dip-coating and subsequent growth by chemical bath deposition (CBD). The rod-like ZnO particles, which were used as a seed layer, were deposited by dipping the substrates into a tetraamine zinc solution. After the seed layer formation, ZnO was grown by CBD. Larger rod-like ZnO particles were synthesized from the base aqueous solution prepared by mixing ZnO, nitric acid, aqueous ammonia, and deionized water. Trisodium citrate and sodium chloride, which were added to the base aqueous solution, influenced surface morphologies and structural properties of ZnO. When trisodium citrate was used, the morphologies changed from rod-like ZnO particles to continuous ZnO films. However, the intensity of the ZnO (002) diffraction peak decreased with increasing trisodium citrate concentration. Continuous ZnO films with a preferred c-axis orientation were obtained from the aqueous solution containing both trisodium citrate and sodium chloride.
Morphology controllable ZnO nanorods on glass substrates were synthesized with controlling concentration of precursors in chemical bath deposition. Effects of concentration of precursors on the morphology, structural and optical properties of ZnO nanorods were investigated. With increasing the concentration of precursors, diameter and length of ZnO nanorods increased, crystallinity and transmittance of ZnO nanorods were improved. ZnO nanorods with large surface area, good crystallinity and high optical transmittance had been achieved by optimizing concentration of precursors. The ZnO nanorods growth mechanism for the influence by concentration of precursors was interpreted in details.