TaON and Ta3N5 as new visible light driven photocatalysts

TaON and Ta₃N₅, Ta⁵⁺-based (oxy)nitrides, were studied as visible light driven photocatalysts. Under visible light irradiation (λ≥420 nm), the (oxy)nitrides oxidize water to O₂ and reduce H⁺ to H₂ in the presence of sacrificial reagents (Ag⁺ and methanol). TaON oxidizes water into O₂ efficiently, with a maximum quantum yield of 10%. The photocatalytic reactions proceed via the bandgap transitions (E_g, TaON: 2.5 eV, Ta₃N₅: 2.1 eV) without any noticeable degradation of the catalysts. The small energy gaps of TaON and Ta₃N₅ are ascribed to the valence band structures consisting of N 2p orbitals.     

Electrodeposition of magnetic CoPd thin films: Influence of plating condition

The manufacture and properties evaluation of Co-based thin film alloys are extensively studied because of their magnetic properties that make them a critical element in many different applications and devices. Therefore the electrodeposition of CoPd alloy thin films was studied from a chloride bath containing glycine as additive. The cobalt content in the CoPd deposits varied from 6.4 to 94.0 at% by controlling the pH and [Co²⁺]/[Pd²⁺] ratio in the bath. Current efficiencies were independent of the solution pH and bath composition. The morphology of the deposits depended on the applied current density: current densities higher than 50 mA cm⁻² resulted in deposits with a typical cauliflower morphology. For current densities lower than 25 mA cm⁻² cracks was observed. The XRD measurements showed that all CoPd alloys were amorphous. The magnetic properties for CoPd alloys revealed that the coercivity (H_c) values ranged from 84 up to 555 Oe and the magnetic saturation (M_s) from 0 to 1.73 T.     

Mechano-catalytic overall water splitting (II) nafion-deposited Cu2O

Some modifications of a mechano-catalyst, Cu₂O, and optimization of the reaction conditions were attempted to improve its activity for mechano-catalytic overall water splitting. The rates of evolution of H₂ and O₂ were improved by deposition of nafion onto Cu₂O and the choice of an appropriate stirring rod. The irradiation of visible light (λ > 550 nm) was found to maintain the activity in the time course, which gradually decreased without irradiation.     

Nonlinear Control VIA Generalized Feedback Linearization Using Neural Networks

A novel approach to nonlinear control, called Generalized Feedback Linearization (GFL), is presented. This new strategy overcomes one important drawback of the well known Feedback Linearization strategy, in the sense that it is able to handle a broader class of nonlinear systems, namely those having unstable zero dynamics. It is shown that the use of a nonlinear predictor for the system output is a key feature in the derivation of the control strategy. For certain types of systems this predictor can be found as a nonlinear function of the system input and output, allowing an output feedback control solution. The use of Artificial Neural Networks (ANN) to directly parameterize the predictor of the controlled variable when an explicit model for the system is not available, is investigated via computer simulations. This approach is based on the functional approximation capability of multi layer ANN.     

Wettability Improvement by Plasma Irradiation and Its Applications to Phase-Change Phenomena

Plasma irradiation is one of the techniques to improve surface wettability. This technique can be used to enhance heat transfer of liquid–vapor phase change. For instance, evaporation of a water droplet can be enhanced by plasma irradiation. The relation between plasma irradiation time and contact angle was examined first for three metals and then the lifetime of a water drop on a hot surface was measured changing the surface wettability by plasma irradiation. The lifetime of the water drop decreased and the wetting limit temperature increased with the increasing irradiation time of plasma. Hydrophilicity by plasma irradiation is not a permanent effect but it will be useful for enhancement of cooling of hot metal.     

Burnett PVT Measurements of Hydrogen and the Development of a Virial Equation of State at Pressures up to 100 MPa

PVT properties were measured for hydrogen by the Burnett method in the temperature range from 353 K to 473 K and at pressures up to 100 MPa. In the present Burnett method, the pressure measurement was simplified by using an absolute pressure transducer instead of a differential pressure transducer, which is traditionally used. The experimental procedures become easier, but the absolute pressure transducer is set outside the constant temperature bath because of the difficulty of its use in the bath, and the data acquisition procedure is revised by taking into account the effects of the dead space in the absolute pressure transducer. The measurement uncertainties in temperature, pressure, and density are 20 mK, 28 kPa, and 0.07 % to 0.24 % (k = 2), respectively. Based on the present data and other experimental data at low temperatures, a virial equation of state (EOS) from 220 K to 473 K and up to 100 MPa was developed for hydrogen with uncertainties in density of 0.15 % (k = 2) at P ≤ 15 MPa, 0.20 % at 15 MPa < P ≤ 40 MPa, and 0.24 % at P > 40 MPa, and this EOS shows physically reasonable behavior of the second and third virial coefficients. Isochoric heat capacities were also calculated from the virial EOS and were compared with the latest EOS of hydrogen. The calculated isochoric heat capacities agree well with the latest EOS within 0.5 % above 300 K and up to 100 MPa, while at lower temperatures, as the pressure increases, the deviations become larger (up to 1.5 %).     

Thermal conductivity reduction of crystalline silicon by high-pressure torsion

We report a dramatic and irreversible reduction in the lattice thermal conductivity of bulk crystalline silicon when subjected to intense plastic strain under a pressure of 24 GPa using high-pressure torsion (HPT). Thermal conductivity of the HPT-processed samples were measured using picosecond time domain thermoreflectance. Thermal conductivity measurements show that the HPT-processed samples have a lattice thermal conductivity reduction by a factor of approximately 20 (from intrinsic single crystalline value of 142 Wm⁻¹ K⁻¹ to approximately 7.6 Wm⁻¹ K⁻¹). Thermal conductivity reduction in HPT-processed silicon is attributed to the formation of nanograin boundaries and metastable Si-III/XII phases which act as phonon scattering sites, and because of a large density of lattice defects introduced by HPT processing. Annealing the samples at 873 K increases the thermal conductivity due to the reduction in the density of secondary phases and lattice defects.     

Relationship between particle size and photochromic characteristics of tungsten oxide films prepared by electric current heating method using tungsten wire

Tungsten oxide films were deposited on glass substrates placed above tungsten wires heated by electric current in air. The film thickness in a region just above the wire (region A) was thinner than that in other region (region B). The observation using scanning electron microscope revealed that the films consisted of particles. The shapes of the particles were sphere in the region A while smaller octahedron shape was found in the region B. The amount of the particles in the region B was greater than that in A. The ratio of the number of small particles with a diameter ≤500 nm to the total particle number in the region A increased with decreasing applied voltage during the electric current heating, whereas, in the region B, the size of particles was ≤500 nm and had no applied voltage dependence. The films exhibited photochromism; the reflectance in the near-infrared region was decreased by the ultraviolet irradiation. In region A, the photochromic effects increased with decreasing applied voltage to the wire. On the other hand, in region B, the photochromic effects did not show the applied voltage dependence. Consequently, it was found that the obtained films showed positive correlation between photochromic effect and the ratio of the number of small particles (≤500 nm) to the total particle number. The particles in region B are suitable for mass production of the photochromic material because the photochromic effect and the amount of particles in region B are greater than those in A.     

Synthesis of single-walled carbon nanotubes using laser-vaporized metal nanoparticle catalyst

SWNTs were synthesized by laser-vaporized CCVD (catalytic chemical vapor deposition). The diameter distributions and the abundance of SWNTs synthesized at different temperatures and using different catalysts were investigated by Raman spectroscopy. Further, this technique was compared with other synthesis techniques (laser-oven and conventional-alcohol CCVD), and C₆₀ was synthesized simultaneously as a byproduct only using the laser-oven technique. With increasing synthesis temperature, the diameter distribution shifted towards larger diameters, and the G/D ratio became larger as the synthesis temperature increased to 1000°C. Ni, Co, and Fe played a catalytic role, though Fe was less effective under our experimental conditions. The diameter distribution of SWNTs synthesized with the Fe catalyst was shifted to smaller values compared to those synthesized with Ni or Co catalysts.     

Reconfiguration management of remanufactured products for responding to varied user needs

In the face of worsening environmental problems, the manufacturing industry is required to reduce resource consumption and environmental loads during product life cycles while responding to diversified user needs without cost increases. In this paper, we propose a reconfiguration method to remanufacture a variety of products using modules extracted from returned products of multiple generations for responding to varied user needs. With this method, we can maximize the sales amount of remanufactured products, which meet the performance requirements of each user group. We demonstrate the effectiveness of the method by applying it to photocopiers.