A novel technique for the preparation of water-soluble carbon nanotubes was demonstrated using a pulsed streamer discharge generated in water. The technique involved chemical reactions between radicals generated by the pulsed streamer discharge and carbon nanotubes. The pulsed streamer-treated carbon nanotubes were homogeneously dispersed and well solubilized in water for a month or longer. The mechanism of solubilization of carbon nanotubes by the pulsed streamer discharge is discussed based on FTIR spectroscopy and optical emission spectra measurements. FTIR spectroscopy revealed that -OH groups, which are known to impart a hydrophilic nature to carbon material, were introduced on the carbon nanotube surface. Optical emission spectra from the pulsed streamer plasma showed that highly oxidative O(*) and H(*) radicals were generated in water. These results suggest that the functionalization of the carbon nanotube surface by -OH group can be attributed to the O(*) and H(*) radicals. An advantage of the proposed method is that there is no need for any chemical agents or additives for solubilization. Chemical agents for solubilization are generated from the water itself by the electrochemical reactions induced by the pulsed streamer discharge.

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A new write strategy (WS) optimization method with a two-step search process for Blu-ray Disc (BD) recording is developed to shorten the optimization time. This method is realized by the WS optimization system, which is constructed with an optical pickup, a disc tester, and the WS optimization algorithm. The optimization is executed according to the two-step search process along the mathematical axis, which is experimentally derived from the sample WS parameters. As the experimental result, the optimization time is reduced by nearly two-thirds from that achieved using the conventional method performed by the experts. All the jitter values of the playback signal derived from the recorded marks are smaller than the 7% target value and the effectiveness of this new method is experimentally confirmed.

SUMMARYIn this study, magnetic iron oxide nanoparticles were produced by thermal treatment of Fe(OH) 3 colloidal solution after graphite arc discharge in the solution. The X-ray diffraction (XRD) pattern of the heat-treated powders showed that magnetic iron oxide nanoparticles (γ-Fe 2 O 3 or Fe 3 O 4 ) were produced by the phase transformation from α-Fe 2 O 2 at the thermal treatment temperature over 500 °C. The XRD pattern also indicated that the graphite powders produced by the arc discharge were contained in the Fe(OH) 3 colloidal solution, suggesting that the graphite powders contributed to the reduction process of α-Fe 2 O 3 .

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