Preparation and photocatalytic activity of Keggin-ion tungstate and TiO2 hybrid layer-by-layer film composites

Keggin ions (PW₁₂O₄₀³⁻ (PW₁₂), SiW₁₂O₄₀⁴⁻ (SiW₁₂), H₂W₁₂O₄₀⁶⁻ (H₂W₁₂)) and TiO₂ hybrid thin films were prepared using the layer-by-layer method. Their photocatalytic activities were investigated using gaseous 2-propanol decomposition. All films were transparent in the visible wavelength range. For 2-propanol decomposition, H₂W₁₂ was the most effective for the combination with TiO₂ despite having the smallest TiO₂ deposition amount. The photocatalytic activity of the PW₁₂–TiO₂ hybrid film was increased 2.3 times by visible light with UV illumination. This increase was less remarkable for hybrid films of other Keggin ions, suggesting that the visible light excitation of reduced PW₁₂ plays an important role in the enhancement of 2-propanol decomposition.     

Interfacial Reaction Between Cu Substrates and Zn-Al Base High-Temperature Pb-Free Solders

Chemical reactions between Cu substrates and Zn-Al high-temperature solder alloys, Zn-4Al and Zn-4Al-1Cu (mass%), at temperatures ranging from 420°C to 530°C were experimentally investigated by a scanning electron microscope using backscattered electrons (SEM-BSE) and an electron probe microanalyzer (EPMA). Intermediate phases (IMPs), β(A2) or β′(B2), γ(D8₂), and ε(A3) phases formed and grew during the soldering and aging treatments. The consumption rate of the IMP for Cu substrates is described by the square root of t in both the alloys, while the additional Cu in the molten Zn-Al alloy slightly suppresses the consumption of Cu substrates. The growth of IMPs during soldering treatment is controlled by the volume diffusion of constituent elements, and its activation energy increases in the order of Q _ε < Q _γ < Q _β. In view of the aging process, the growth of IMPs is considered to be controlled by the volume diffusion. In particular, the layer thickness of γ rapidly grows over 200°C, although the thickness of the β layer grows very slowly.     

A 120-W Boost Converter Operation Using a High-Voltage GaN-HEMT

A boost converter with a 940-V/4.4 A GaN-HEMT as the main switching device was demonstrated to show the possibility of using high-voltage GaN-HEMTs in power electronic applications. The demonstrated circuit achieved an output power of 122 W and a power efficiency of 94.2% under a drain peak voltage as high as 350 V and a switching frequency of 1 MHz. The dual field-plate structure realized high-voltage switching operation with high power efficiency as dynamic on-resistance was suppressed by an increase of the current collapse phenomena.     

Development of an Artificial Lipid-Based Membrane Sensor with High Selectivity and Sensitivity to the Bitterness of Drugs and with High Correlation with Sensory Score

This paper reports the development of membrane sensors based on an artificial lipid and plasticizers with high selectivity and sensitivity to drug bitterness by using bis(1-butylpentyl) adipate (BBPA), bis(2-ethylhexyl) sebacate (BEHS), phosphoric acid tris(2-ethylhexyl) ester (PTEH), and tributyl o-acetylcitrate (TBAC) as a plasticizer and phosphoric acid di-n-decyl ester (PADE) as an artificial lipid to optimize surface hydrophobicity of the sensors. In addition, a sensor with highly correlated bitterness sensory score was developed by blending BBPA and TBAC to detect the bitterness suppression effect of sucrose, and other bitter-masking materials. Therefore, this sensor can be used to evaluate the bitterness of various drug formulations with high accuracy. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Size dependence of THz region dielectric properties for barium titanate fine particles

Barium titanate (BaTiO₃) crystallites with various particle sizes from 22 to 500 nm were prepared by the two-step thermal decomposition method of barium titanyl oxalate. Various characterizations revealed that these particles were impurity-free, defect-free, dense BaTiO₃ particles. The powder dielectric measurement clarified that the dielectric constant of BaTiO₃ particles with a size of around 58 nm exhibited a maximum of over 15,000. To explain this size dependence, the THz region dielectric properties of BaTiO₃ fine particles, especially Slater mode frequency, were measured using the far infrared (FIR) reflection method. As the result, the lowest Slater mode frequency was obtained at 58 nm. This tendency was completely consistent with particle size dependence of the dielectric constant.     

Development of lateral displacement sensor for real‐time detection of structural damage

We have developed a novel sensor that enables us to measure the relative story displacement of a building structure in real time. This lateral displacement sensor (LDS) is composed of a light‐emitting diode (LED) array, which is fixed on the ceiling, and a position‐sensitive detector (PSD) unit, which is placed on the floor. We optimized the LDS to achieve high accuracy in lateral displacement measurement. The accuracy was evaluated to be 60 µm by conducting shaking table tests. Two LDSs were implemented in an actual building equipped with an active variable stiffness (AVS) system, and the building was vibrated with seismic waveforms by an exciter placed on the rooftop. The seismic displacement of the second floor relative to the first floor was measured using the LDS. Furthermore, the inclination angle of the second floor could be measured using the LDS during the seismic vibration. Using the AVS system, we realized the residual displacement of the second floor without inducing damage to the building, and succeeded in real‐time residual displacement measurement for the first time. These results indicate that the LDS is useful for the health diagnosis of a building structure. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Anti-aging effects of caloric restriction: Involvement of neuroendocrine adaptation by peripheral signaling

Many hormonal signals from peripheral tissues contribute to the regulation of energy homeostasis and food intake. These regulators including leptin, insulin, and ghrelin, modulate the orexigenic and anorexigenic neuropeptide expression in hypothalamic nuclei. The anti-aging effects of caloric restriction have been explained from an evolutional viewpoint of the adaptive response of the neuroendocrine and metabolic response systems to maximize survival during periods of food shortage. In organisms, excess energy is stored in adipose tissues as a triglyceride preparation for such survival situations. Adipose tissue has recently been recognized as an endocrine organ, and leptin, as secreted by adipocyte, seems to be an especially important factor for the adaptive response to fasting and neuroendocrine alterations under caloric restriction. In this review, we discuss the potential involvement of neuroendocrine modulators in longevity and the anti-aging effects of caloric restriction.     

Metal and Nonmetal Codoped 3D Nanoporous Graphene for Efficient Bifunctional Electrocatalysis and Rechargeable Zn–Air Batteries

Developing bifunctional electrocatalysts with high activities and long durability for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial toward the practical implementation of rechargeable metal–air batteries. Here, a 3D nanoporous graphene (np‐graphene) doped with both N and Ni single atoms/clusters is reported. The predoping of N by chemical vapor deposition (CVD) dramatically increases the Ni doping amount and stability. The resulting N and Ni codoped np‐graphene has excellent electrocatalytic activities for both the ORR and the OER in alkaline aqueous solutions. The synergetic effects of N and Ni dopants are revealed by density functional theory calculations. The free‐standing Ni,N codoped 3D np‐graphene shows great potential as an economical catalyst/electrode for metal–air batteries.     

Detection of fluorescence from a mixed specimen consisting of micro particles attached to different fluorescent substances using a light waveguide incorporated optical TAS

A “ubiquitous human health care system” will require a monolithic optical total analysis system (TAS) consisting of waveguides and microfluidic channels based on a transparent resin chip. Together with the rapid development of the fluorescent marking method, fluorescence analysis by TAS of mixed-microparticle specimen attached to different fluorescent substances will be necessary. Towards realization of this, we here propose a novel method for using a part of the fluorescence acquired by irradiating microparticles with AC-modulated laser power as light dedicated to the discrimination of fluorescent substances. Since the light power for discrimination was extremely weak, we extracted effective signal components using a lock-in detection method. Then, by comparison with the signal of the original fluorescence, we could determine whether the fluorescence signal was from the microparticles attached to the fluorescent substance to be discriminated. Using a mixed specimen composed of microparticle-attached fluorescent substances with emission peaks of 520 nm and 600 nm, we found that 10% of the acquired fluorescence could successfully determine the specified fluorescent substance as a discrimination signal. The peak value of the discrimination signal was approximately double the amplitude of the stationary noise in the discrimination signal.

     

Inhibiting Surface Diffusion to Synthesize 3D Bicontinuous Nanoporous N-Doped Carbon for Boosting Oxygen Reduction Reaction in Flexible All-Solid-State Al-Air Batteries

Catalyzing oxygen reduction reaction (ORR) and accelerating oxygen diffusion are two key challenges for the requirements of the cathode catalysts in the metal-air batteries. A promising strategy for improving both ORR performance and mass diffusion simultaneously is to build carbon-based catalysts with ORR-active chemical dopants and 3D interconnected porosity. Herein, a 3D nanoporous N-doped carbon with bicontinuous porosity and interconnected open-pore channels is reported, which is prepared by a polyaniline-assisted template method. The polyaniline can efficiently inhibit the surface diffusion-caused template coarsening, achieving a small pore size of 35 nm. The small porous morphology gives rise to a high N-dopant concentration up to 7.20 at.%, which in turn exhibits a commercial Pt/C-comparable ORR performance together with satisfied durability in alkaline media. Using these nanoporous carbon catalysts as air electrodes, an all-solid-state flexible Al-air battery is assembled with the measured maximum power density reaching 130.5 mW cm⁻², as compared to 106.2 mW cm⁻² when the commercial Pt/C standard is used. This study provides an efficient method to synthesize 3D N-doped carbon with bicontinuous nano-sized pore channels for wide-ranging applications in portable and flexible devices.