An energy cycle using solar power and metals has been proposed. High repetitive laser pulses are generated by a solar-pumped laser or a laser generated using solar power, and the laser pulses are irradiated to metal oxides in liquid. We can obtain reduced metal nanoparticles with this method, and solar power is effectively stored as chemical energy. We fabricated Li air fuel cells using sintered Iron or Aluminum nanopaste plates as negative electrodes. Electricity was successfully produced from these cells. The observed maximum output voltage of the Al paste Li air cell was 2.9 V when they were connected to a low load. The Fe or Al paste Li air cells are expected to become common power supplies with high-energy density and high output power.

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The photoreduction of Sm³⁺ to Sm²⁺ was studied by a means of the nanosecond laser flash photolysis using a KrFexcimer laser with the oscillation wavelength of 248 nm. Sample was air-saturated methanol solution of 15-crown-5 with SmCl₃. The photoreduction occurred via a one-photon process. The reduction yield at 1 µs after the laser irradiation was estimated to be 0.37±0.05.

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A carbon fiber reinforced plastic [CFRP] is widely used for automobile, aircraft and so on, because of high strength, lightweight and weather resistance. It is difficult to cut a CFRP plate since it is composed of carbon fiber and epoxy resin. The CFRP plates were cut with nanosecond laser at the wavelengths of 1064 nm. After the laser irradiation, heat affected zones (HAZs) of CFRP plates were evaluated with scanning electron microscope and Raman spectroscopy to distinguish matrix evaporation zone (MEZ) from resin alteration zone (RAZ). The results indicated that the size of the MEZ formed under argon gas was smaller than that under air.

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Femtosecond laser nano-ablation of Ti by short-pulse laser irradiation (800 nm/40 fs) is studied in the laser fluence range of 0.07-0.5 J/cm². To determine the ablation threshold, the ablation rate dependence on laser fluence is precisely measured. Multi-shot ablation threshold of titanium is found to be 0.074 J/cm² in which value is good agreement with that reported previously by other group. To discuss the ablation mechanism, all the ablation thresholds for metals previously published are plotted as a function of work function and melting temperature. We found that the ablation thresholds correlated with work function of metals. Experimental data suggested that the femtosecond laser ablation is mainly due to multi-photon absorption and optical field ionization.

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In a conventional laser peening (C-LP) without a protective coating, a treated metallic surface is always melted after the C-LP processing, resulting in the generation of tensile residual stress. In order to establish a new LP technique without surface melting, we have investigated the effect of an LP (Ink-LP) using a black liquid ink (an indian ink) as an absorber. The laser wavelength and pulse duration of the laser used were 532 nm and ∼5 ns, respectively. We changed the pulse energy and spot diameter of the laser beam, resulting in the corresponding power density of ∼1 - 15 GW/cm². The pulse number was 1. The metal sample used was an aluminum alloy (A2017). As a reference, we have conducted similar experiments for the C-LP processing, which in the metallic surface are directly irradiated, and have compared surface deformation and surface melting between the Ink-LP and C-LP processing. As a result, it was found that the Ink-LP processing can provide us with a promising LP effect with a wider treatment area and no surface melting in comparison with those of the C-LP processing. Thus, we have showed the usefulness of the Ink-LP processing using a black ink.

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Titanium (Ti) is one of the most used biomaterials. However, it has problem for biocompatibility. Adding new function to Ti surface is necessary. Coating of titanium dioxide (TiO₂) film on Ti surface is a useful method for improving the biocompatibility of Ti. We have a film coating method with an aerosol beam. Control of cell spreading by periodic nanostructures formation with femtosecond laser is also useful method for adding new function to TiO₂ film. The control of cell spreading is important for the development of advanced biomaterials. In this study, the periodic nanostructures with periods of 130 and 230 nm were formed on a film using a femtosecond laser with wavelengths of 388 and 775 nm, respectively. Effect of periods on cell spreading was investigated. Cell tests showed that cells spread along the grooves of the periodic nanostructures with periods of 130 and 230 nm, whereas cell spreading did not have a definite direction on a film without periodic nanostructures. Distribution of angle of cell spreading on laser irradiated area was examined. These results suggested that controlling the cell spreading on periodic nanostructures with period of 230 nm was better than that of 130 nm.

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In 2008, International Electrotechnical Commission (IEC) prescribed an immunity test (IEC61000-4-2) of electronic equipment against electrostatic discharges (ESDs), and provided a theoretical ESD current based on a Heidler's formula. For the current waveform, however, not the whole waveform but only the rise time, the first peak, and the current values at 30 ns and 60 ns are specified in the time domain along with their variability so that a commercially available ESD generator (ESD gun) shall be calibrated by checking whether or not the injected current onto an IEC recommended current target meets the IEC specification. In this study, to propose in the frequency domain the allowable variability of IEC specified current waveforms, we calculated the frequency spectra of theoretical current waveforms obtained by changing the parameters in the Heidler's formula, which were compared with those of discharge currents measured for contact discharges of commercially available ESD guns onto the IEC target. Results enabled us to give the allowable variability in the current spectra with respect to the theoretical current waveform, which is from -5 dB to +4 dB up to 400 MHz and from -6 dB to +8 dB over 400 MHz, while the measured waveforms that meet the IEC standard in the time domain have the spectra greater than +8 dB over 1 GHz due to the distortion of the current rising waveforms, although they fall in the allowable range below 1 GHz.

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The influence of the gas pressure on the dielectric barrier discharge with plate electrode was investigated for generating high density Ozone gas. It was impossible for discharge type Ozone gas generator to make ultrahigh density Ozone gas upto 26wt% because of Ozone decomposion by electron impacts. To make ultrahigh density Ozone gas, Ozone gas was condensated on the silicagel in the cooled adsorption column. It was possible to generate 80∼100wt% Ozone gas continuously switching two adsorption column.

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To clarify the relation between the ON-voltage of power semiconductors in the inverter and the magnetic properties such as iron loss and the magnetic hysteresis curves, the PWM shaped voltage with the virtual ON-voltage is realized experimentally by means of an arbitrary function generator and an amplifier excitation. The iron loss and the width of the minor loop increase linearly with the increasing ON-voltage. Therefore, if the inverter made a virtual voltage waveform generated by a low ON-voltage of the power semiconductor, the iron loss would be reduced.

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In order to apply REBa₂Cu₃O_y (REBCO: RE=Rare Earth) superconductor, the superconducting properties of REBCO in magnetic field should be improved. For the improvement the superconducting properties, we focused on LaBa₂Cu₃O_y superconductor. The LaBCO has the highest critical temperature (T_c) among REBCOs. On the other hand, it is very difficult to obtain high T_c LaBCO thin films because LaBCO is easily substitutes La³⁺ ions for Ba²⁺ sites and forms solid solutions which have low T_c. For this problem, we used Vapor-Liquid-Solid growth mode (VLS) in fabricating the LaBCO epitaxial films in order to prevent La/Ba substitutions. In this study, we investigated an effect of the VLS growth mode on the superconductivities in the LaBCO thin films and also studied substrates dependence of LaBCO thin films fabricated on various substrates and a buffer layer. From comparison between a VLS-LaBCO film and a conventional LaBCO film, we confirmed that the VLS growth mode was able to prevent the La/Ba substitutions. We compared superconducting properties of LaBCO thin films prepared on various substrates and a buffer layer and found that superconducting properties of LaBCO thin films was influenced by both the strain arising from the substrates and LaBCO crystallinity.

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Polyethylene is widely used for electrical insulation in transmission cables. Although the degradation process of polymers is correlated with space charge formed in the material, there remains a lack of understanding of charge transport phenomena. In this paper, characterization of charge transfer models in polymers and current accomplishments of quantum chemical computational schemes are briefly reviewed. In addition, in order to obtain a better understanding of charge transport phenomena in polyethylene, the quantitative evaluation of charge transport based on perturbation approach is applied to polyethylene dimer; electronic coupling matrix element is calculated by means of standard density functional theory. These values are compared with the results of existing computational schemes. It is shown that computation of electron coupling matrix element is essential to discuss charge transfer phenomena.

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A novel method was proposed to judge degradation/health of lithium-ion batteries using the capacitance that was estimated from the real-time voltage and current characteristics of the batteries. It is thought that the capacitance of lithium ion batteries decreases with degradation because of undesirable components formed on the electrodes that are the main cause of the degradation. As the lithium ion batteries are active, the capacitance was evaluated from the differential equation, ΔQ/Δv = I/(Δv/Δt) = i/(dv/dt), using the voltage and the current characteristics during the charging or the discharging. The capacitances of the commercial LIBs with different SOHs; 100, 92 and 88% were estimated during the charging and the discharging using the equation. The average capacitance in the specific voltage region of the batteries was directly proportional to the state of health. Therefore, the proposed measurement is thought to be a useful method for judging degradation of lithium-ion batteries.

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