Photoelectrochemical decomposition of bio-related compounds at a nanoporous semiconductor film photoanode and their photocurrent-photovoltage characteristics

Photoelectrochemical decomposition of bio-related compounds such as amino acids was investigated with a biophotochemical cell comprising a mesoporous TiO₂ thin film photoanode and an O₂-reducing cathode. It was concluded that a kind of Schottky junction formed at the surface of the TiO₂ (called as liquid junction) induced the photodecomposition followed by generation of photocurrent/photovoltage. Complete photodecomposition was investigated by the CO₂ formation yield. The photocurrent-photovoltage (J-V) characteristics of amino acids and other typical bio-related compounds were investigated, and the short circuit photocurrent (J_sc), open circuit photovoltage (V_oc), and Fill factor (ff) were exhibited. Effect of pH on the photodecomposition of phenylalanine and cysteine were studied; for cysteine alkaline conditions gave a high efficiency, which was interpreted by the high electron-donating ability of the dissociated -S⁻ group. The incident light-to-current conversion efficiency (IPCE) of cysteine was 25% at 350 nm. It was for the first time shown that organic acids gave high internal quantum efficiency (η′) over 8 (=800%) in the photodecomposition; for oxalic acid it was 9.3 (=930%) and for butyric acid 8.2. The alternating current impedance spectroscopy of glycine showed that the cell performance is determined by the chemical reactions at TiO₂ or Pt electrodes.     

Internal oxidation of Fe-Al alloys in the α-phase region

The internal oxidation behavior of Fe-0.069, 0.158, and 0.274 wt% Al alloys was investigated in the -phase region. The internal oxidation experiments have been made over the temperature range from 1023 to 1123 K using a mixture of iron and its oxide powders. A parabolic rate law holds in the present alloys, where the rate constant, K_p, depends upon the oxidation temperature as well as the aluminum content. The internal oxidation of Fe-Al alloys is, therefore, controlled by a diffusion process of oxygen in the alloy. The oxide formed in the oxidation layer is the stoichiometric FeAl₂O₄ (hercynite). The aluminum concentration, N _Al ^Io , in the oxidation layer was calculated by taking account of counterdiffusion of aluminum. Furthermore, the oxygen concentration, N _O ^S , at the specimen surface was evaluated on the basis of thermodynamics. Using these estimated values of K_p, N _Al ^IO , and N _O ^S , the diffusion coefficient of oxygen, D _O ^IO , in the oxidation layer, where the oxide particles were dispersed, was also calculated. D _O ^IO increases as the volume fraction of the oxide, f^IO, increases. The diffusion coefficient of oxygen, D_O, in -iron was determined by extrapolating D _O ^IO to f^IO=0.     

Characteristics of interfacial profiles in upward and downward gas-liquid two-phase plug flow

Gas-liquid interfacial profiles in plug flow for both upward and downward flows were obtained using semi-supermultiple point-electrode probes, comprising 67 sensing tips arranged on a tube diameter. Typical interfacial profiles are demonstrated for both flows. Close inspection of the profiles reveals that four zones exist in a pair of gas and liquid slugs for upward plug flow and a high slip velocity region in downward plug flow. The lengths of the swelling liquid front zone and the wake zone were determined. The length of the wake zone strongly depends on the relative velocity between the liquid film around the gas slug and the liquid phase in the liquid slug. Characteristic distributions of bubbles within liquid slugs were found, i.e., three types of radial distributions of void fraction, namely saddle-shaped, trapezoidal and bullet-shaped distributions, exist for upward flow. The two types for downward flow exclude the saddle-shaped distribution. © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25 (8): 568–579, 1996     

Breaking Ability and Interrupting Phenomena of a Circuit Breaker Equipped with a Parallel Resistor or Capacitor

This paper discusses the breaking ability of an air blast circuit breaker (ABB) or SF6 gas circuit breaker (GCB), and the interrupting phenomena around current zero in the case where a resistor or capacitor is connected in parallel with its interrupter to improve the breaking ability. It has been clarified that the use of a parallel resistor for ABB, and that of a parallel capacitor for GCB are the most effective methods to improve the breaking abilities; the parallel resistor not only serves to reduce the rate of rise of the transient recovery voltage (rrrV), but also shifts the current from the interrupter to itself around the current zero, thus reducing the stress for interruption. The improvement of the breaking ability is achieved by reducing the initial average rrrV between zero and 1 microseconds (inherent value), when the parallel capacitor is used with the GCB.     

Speech recognition using pulse-coupled neural networks with a radial basis function

We have developed a novel pulse-coupled neural network (PCNN) for speech recognition. One of the advantages of the PCNN is in its biologically based neural dynamic structure using feedback connections. To recall the memorized pattern, a radial basis function (RBF) is incorporated into the proposed PCNN. Simulation results show that the PCNN with a RBF can be useful for phoneme recognition. This work was presented in part at the 7th International Symposium on Artificial Life and Robotics, Oita, Japan, January 16–18, 2002     

Biomimetic ion-channel sensors based on host-guest molecular recognition in Langmuir-Blodgett membrane assemblies

Biomimetic “ion-channel sensors” based on host-guest molecular recognition were constructed by incorporating several kinds of receptor molecules in Langmuir-Blodgett (LB) molecular assemblies deposited directly on glassy carbon electrodes. The receptors used were valinomycin, bis(crown ether)s, macrocyclic polyamine and cyclodextrin polyamine. The binding of charged stimulants (metal ions, inorganic and organic anions) to these receptors induced a marked increase (or decrease) in the ion permeability of the membranes, as detected by cyclic voltammetry using [Fe(CN)₆]^4- or [Ru(bpy)₃]²⁺ as marker ion. Such a mode of response, corresponding to model “channel opening (or closing)”, can be explained on the basis of the charge-charge interaction involving the stimulant, marker ion and lipid.     

Bioelectromagnetics researches in Japan for human protection from electromagnetic field exposures

Research works on bioelectromagnetics in Japan are reviewed with a focus on the efforts devoted to the issue of human protection from electromagnetic field (EMF) exposures. History of this issue in Japan is briefly reviewed first for all EMF spectra. Then research works on radiofrequency (RF) EMF are summarized in more detail. The RF studies reviewed are mainly conducted in the framework of research program by the Ministry of Internal Affairs and Communications (MIC) started in 1997. Because of this program, collaborations between biology/medicine and engineering have been promoted. The results consistently show no evidence against the safety of RF‐EMF within the exposure levels of internationally accepted guidelines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Technology interaction of Electrical Engineering

The paper reviews the global activities of the Technical Committee for History of Electrical Engineering (HEE) in Institute of Electrical Engineers of Japan (IEEJ) to discuss its future activities. Introducing HEE global activities in the Maui Meeting (MM) and International Conference on Electrical Engineering (ICEE), the paper discusses the framework of the International Joint Study Programme for History of Technology Interaction (IJSP/HTI) on the basis of its current study conducted by the Investigation Committee for International Joint Study for History of Technology Interaction (IC/HTI). It concludes the discussion with the view that the study of history could serve as a foundation for us to achieve global contributions in the field of engineering as well. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Polymers degradable under environmental conditions through end-modification of poly(α-methylstyrene) derivatives

To induce degradabilities in polymers in response to environmental conditions, the end-modification reactions of poly(α-methylstyrene) derivatives were carried out. When diphenylphosphine chloride was used as a modifier for the living end of para-substituted PMS, the coupling efficiency was ca. 50%. 2-Phenylallyl halide derivatives such as 2-phenylallyl bromide, 2-(4-tolyl)allyl bromide, and α-trifluoromethylstyrene were found to be suitable end-modification agents. For example, ω-2-phenylallyl PMS was prepared with almost quantitative functionality by the reaction of the living PMS with 2-phenylallyl bromide. In a similar way, ω-3,3-difluoro-2-phenylallyl and ω-2-(4-tolyl)allyl PMS derivatives were synthesized. Based on thermogravimetric analysis, onset of the degradation temperature of the end-modified PMS derivatives decreased in the following order: ω-hydrogen- > ω-3,3-difluoro-2-phenylallyl- > ω-2-phenylallyl- > ω-2-(4-tolyl)allyl-PMS. Actually, the onset temperature of ω-2-(4-tolyl)allyl-PMS derivatives was 50°C lower than that of ω-H-PMS derivatives. These results indicate that the active species is produced effectively at the end unsaturated bond, which initiates the depolymerization of the polymer at rather low temperatures. Ionic degradation of these polymers was also investigated using butyllithium as an anionic initiator and methanesulfonic acid as a cationic initiator. Tendencies similar to the thermal degradation were observed. Therefore, it is concluded that a 2-phenylallyl substituent at the end of the PMS chain induces effective degradation through several mechanisms such as radical, anionic and cationic depolymerization reactions.