Seisuke Kano

Application of hydroxyapatite-sol as drug carrier

The application of hydroxyapatite-sol as a drug carrier is being developed. Hydroxyapatite-sol which is a suspension consisting of hydroxyapatite nano-crystals, was synthesized using an ultrasonic homogenizer. The size of the crystals was 40 x 15 x 10 mm3 on average and their specific surface area was 100 m2/g. An amount of a glycoside antibiotics adsorbed onto hydroxyapatite nano-crystals was measured. The drug adsorbed 0.2 mg per 1 mg of hydroxyapatite. The affect of the drug adsorbed onto the hydroxyapatite was investigated using cancer cells. The drug, adsorbed onto the hydroxyapatite nano-crystals, inhibited cancer cell growth.

Evaluation of Morphology and Size Distribution of Silicon and Titanium Oxide Nanoparticles Generated by Laser Ablation

Nanometer-sized particles of silicon and titanium oxide were generated by irradiating solid targets using a nanosecond pulsed-Nd : YAG laser in a low pressure atmosphere. A low pressure differential mobility analyzer (LP-DMA) was used to classify the size of the generated particles. The LP-DMA and electron microscopes (SEM and TEM) were used to measure the change in the size distribution and morphology of the generated particles with laser power density and system pressure. The size distribution of both silicon and titanium oxide ranged from two to one hundred nanometers in diameter depending on the laser power density and pressure. From the high resolution TEM observation and electron diffraction, it was found that the generated titanium oxide nanoparticles were composed of a ‘core’ of faceted metallic single crystals with an oxide layer shell’.

Irradiation of CW-CO2 laser on a powder target. Formation of fullerene film from graphite powder

Abstract A process was investigated to irradiate a continuous-wave CO 2 laser (4.5 kW) on graphite powder with a mean diameter of 5 μm in a flow of Ar or He gas at 30 or 200 Torr. The film produced on a Ni substrate in the Ar flow at 200 Torr showed the Raman bands of C 60 and C 70 , and the C 60 /C 70 ratio was estimated to be 5/1 by MALDI-TOF mass spectrometry. The film formation process is discussed on the basis of an analysis of laser-irradiated powder, which included 0.01 wt% of C 60 , by UV–Vis absorption, and by observations of the plumes and SEM images.

In situ monitoring of friction surfaces and their sequence pattern analysis

Friction occurs between solid surfaces, and even sometimes on lubricated surfaces. To understand tribological subjects, it is important to know the changes that occur in friction surfaces. In this study, a laser strobe technique is applied to a friction surface observation. The recorded surface images were analysed using pattern-matching methods and their correlations are discussed. A test using pin-on-plate methods with carbon steels was performed using a reciprocating motion speed of 10 Hz for 4.9 N. A pulsed laser light (Nd:YAG SHG=532 nm, 5 ns per pulse) was irradiated onto the friction surface. It was induced using an optical microscope that was located just to the side of the pin. The laser pulse was synchronized with the plate motion, which was a trigger of the laser pulse. The surface image was stored for every cycle. These sequences were calculated and their correlations were analysed as a function of the surface pattern and the friction track size and shape. Analysis revealed that some groups were distinguishable as parameters of the damage size and shape.

Mechanical Behavior of Single Crystal Copper for Different Shearing Directions

The mechanical behavior of the surface of metals is strongly affected by surface fracture occurring in the process of mechanical shearing, especially in shaper-type cutting performed for the application of ultra-fine optical manufacturing and several types of nanotechnology. This discussion aims to elucidate the tribological behavior of pure Cu. In ultra-precise cutting, the physics of crystallographic interfaces is extremely important for controlling surface fracture behavior. In this study, surface fracture behavior was evaluated using single crystal copper cut in two different directions (along the (100) and (111) planes). For V-shaped groove cutting, the flat copper surface was cut with a diamond-tip cutting tool (with a V angle of 90°, a rake angle of 0°, and an escape angle of 7°) at a machining speed of 4-4000 mm/min and a cutting depth of 0.2-10 m. The machined surface was observed with a laser scanning microscope and compared with two groove shapes, in which the cutting grooves in the two cutting directions were found to be different. This result was considered to depend on whether the cutting tool moved along the slip planes {111}, which are oriented in the direction. In the case of shallow cutting (under 1 m), the springback behavior became apparent for cutting in the slip plane direction, where the mechanism of this behavior would be associated with the interface between slip-plane fractures created by the cutting tool.

Surface Treated PDMS by UV-Vis Light for Microfluidic Device

Hydrophobic property of PDMS surface was improved by the 400 W UV-Vis lamp light irradiation in the atmospheric condition for several ten minutes. As a result of this surface treatment, the surface became to hydrophilic character for one month long. This surface treatment technique applied to PDMS micro-fluidic device and verified valve-less switching. The UV-Vis light irradiated to PDMS micro fluidic pattern with partly covered by aluminum foil. Finally inlet and outlets were connected 0.5 mm diameter tubes. The syringe pumps injected the distilled water into the inlet of the PDMS micro channel at the flow rates of 0.5, 5.0, and 50 μl/min for the both width channel. As results of water injection water flowed only the UV-Vis treated channel at the flow rates of 0.5 and 5.0 μl/min. On the other hand, the water flowed for all channels at the flow rate of 50 μl/min. This result was observed from 5.0 μl/min flow again for both width devices which dried by air. These results were occurred by the difference of the flow conductance and wettability. The mechanism of this hyrophilicity of PDMS was reported to form Si-O in the surface by means of glassy surface. From the IR spectra, the Si-O-Si peak shifted to higher wave number for UV-Vis irradiated PDMS than the untreated PDMS comparing with the other IR peaks. This result showed that the Si-O-Si network bonding of PDMS changed to the O-Si-O bonding around the surface.

Multi-oxides thin film formation on iron-base metal by YVO4 pulsed laser color marking

Multi-oxidized thin films were fabricated by applying laser color marking technique on a stainless steel surface with laser irradiation using an YVO4 pulsed-laser at 30 kHz in atmospheric conditions. These multi-oxidized thin films emitted several colors including purple, violet, ultramarine, orange, and green. Using this technique, these mono-colors were produced on the surface according to the scanning repetition number and laser power. Results of XRD analyses for the colored areas showed several types of oxides consisting of FeO, Fe3O4, CrO, Cr2O3, Cr3O4, NiO, Ni2O3, NiCr2O4, and their mixed oxides, which consisted of oxygen vacancy structures. Each of these oxides has its original color for each composition and structure if the mono-phase area producing it shows clear mono-color corresponding to the composition and structure.Multi-oxidized thin films were fabricated by applying laser color marking technique on a stainless steel surface with laser irradiation using an YVO4 pulsed-laser at 30 kHz in atmospheric conditions. These multi-oxidized thin films emitted several colors including purple, violet, ultramarine, orange, and green. Using this technique, these mono-colors were produced on the surface according to the scanning repetition number and laser power. Results of XRD analyses for the colored areas showed several types of oxides consisting of FeO, Fe3O4, CrO, Cr2O3, Cr3O4, NiO, Ni2O3, NiCr2O4, and their mixed oxides, which consisted of oxygen vacancy structures. Each of these oxides has its original color for each composition and structure if the mono-phase area producing it shows clear mono-color corresponding to the composition and structure.

Fabrication of well-defined silicon and titanium oxide nanoparticles by laser ablation

Nanometer-sized particles of silicon and titanium dioxide were generated by Nd:YAG laser ablation of solid substrates in a low pressure atmosphere. A low-pressure differential mobility analyzer (LP-DMA) was used to control the size of generated particles. The LP-DMA and a transmission electron microscopy (TEM) were used to measure the change in size distribution and morphology of nanoparticles with laser power and pressure. Finally, we succeeded to synthesize the almost spherical nanoparticles of 2-50 nm in diameter.

Fullerene synthesis from carbon powder using CW-CO2 laser

A semi-continuous process for the synthesis of fullerenes is described. This novel process incorporated a carbon powder feed system in combination with a continuous-wave CO2 laser irradiation source. The carbon powder contained no fullerenes but did contain graphite crystals and amorphous carbons of selected particle sizes (5, 10, or 20 μm), and selected irregular or spherical particle shapes. The method was successfully used to deposit C60 and C70 powders and films continuously. Laser irradiation of the carbon powder produced an observable laser plume. The experimental results and mechanism for the process are discussed.

Laser glazing of pure iron using high-power CO{sub 2}-gas laser

The surface of pure iron was glazed with a high-power CO2-gas laser to improve its surface hardness. The conditions of the CO2-gas laser were 1.6x105 W/cm2, continuous wave and multi mode at 5 kW. This laser beam was irradiated on the pure iron (99.9 wt%) surface under an Ar-gas (0.2 torr) atmosphere. The size of iron was 14x17x70 mm3. Microvickers hardness increased to 530 Hv (laser irradiated surface) from 257 Hv (substrate surface). The mechanism of increased hardness was analyzed with scanning electron microscopy and X-ray diffraction of the surfaces of both the laser irradiated and substrate iron. The SEM images showed that the laser glazed surface consisted of cross packed grains but the substrate surface included many micro pores. The hardened area had no boundary with its substrate and also had no cracks. From the results of XRD measurements, the patterns of the glazed surface partly changed to the amorphous phase and the relative intensity of (200) peak par (110) peak of δ-Fe changed to smaller than that of the substrate. These results suggested that the reasons for the increased hardness of the laser glazed surface were the disappearance of micro pores and the appearance of fine grains and amorphous phase.The surface of pure iron was glazed with a high-power CO2-gas laser to improve its surface hardness. The conditions of the CO2-gas laser were 1.6x105 W/cm2, continuous wave and multi mode at 5 kW. This laser beam was irradiated on the pure iron (99.9 wt%) surface under an Ar-gas (0.2 torr) atmosphere. The size of iron was 14x17x70 mm3. Microvickers hardness increased to 530 Hv (laser irradiated surface) from 257 Hv (substrate surface). The mechanism of increased hardness was analyzed with scanning electron microscopy and X-ray diffraction of the surfaces of both the laser irradiated and substrate iron. The SEM images showed that the laser glazed surface consisted of cross packed grains but the substrate surface included many micro pores. The hardened area had no boundary with its substrate and also had no cracks. From the results of XRD measurements, the patterns of the glazed surface partly changed to the amorphous phase and the relative intensity of (200) peak par (110) peak of δ-Fe changed to smaller t...