Fabrication of diamond-like carbon film on rubber by T-shape filtered-arc-deposition under the influence of various ambient gases

Diamond-like carbon (DLC) films were prepared on rubber substrates using T-shape filtered-arc-deposition (T-FAD), which effectively removes the macrodroplets emitted from the graphite cathode spot from the processing plasma. In the present study, the influence of ambient gas (no gas, Ar, H₂, C₂H₂, C₂H₄, CH₄) was investigated. The DLC films adhered well to the rubber substrate. When the substrate was stretched, the small DLC islands were separated and clefs were opened. The deposition rate on rubber was approximately twice higher than that on a Si substrate. When hydrocarbon gas was introduced as an ambient gas, the deposition rate became higher than that for no gas and H₂ gas. In the cases of C₂H₄ and CH₄ gases, the DLC film was considered to contain a considerable amount of hydrogen. When C₂H₂ gas was used, the highest deposition rate with less surface roughness was achieved.     

Crystal quality of a 6H-SiC layer grown over macrodefects by liquid-phase epitaxy: a Raman spectroscopic study

Liquid-phase epitaxial (LPE) growth on silicon carbide simultaneously covers macroscale defects, e.g. micropipes, and improves the quality of the crystal. In this study, an epi-layer grown over a macrodefect was evaluated by micro-Raman scattering spectroscopy. Before the growth process, the density of the stacking fault was high and the carrier density spatially inhomogeneous in the vicinity of the macrodefects. On the other hand, after growth, the layer over the macrodefect displayed good quality; the density of the stacking fault was less than that before growth and the homogeneity of the carrier density improved.     

Red‐phosphorescent OLEDs employing bis(8‐quinolinolato)phenolato‐aluminum(III) complexes as emission‐layer hosts

Abstract— We have used bis(8‐quinolinolato)phenolato‐aluminum complexes as emission‐layer hosts in red‐phosphorescent OLED devices. This enabled high‐efficiency long‐lived OLED devices with a simple device structure that does not require a hole‐blocking layer. Devices with a red‐phosphorescent dopant introduced into a noble bis(8‐quinolinolato)phenolato‐aluminum complex exhibited a high efficiency of 12 cd/A at CIE color coordinates (0.65, 035) and a long operating lifetime of 30,000 hours or more at an initial luminance of 700 cd/m². Moreover, triplet‐triplet annihilation was reduced in the devices because of the wide emission zone enabled by the complex and the short phosphorescent lifetime of the red‐phosphorescent dopant. We have successfully incorporated these red‐phosphorescent devices into commercial OLED displays.     

Some conditions which make the constantly scaled H∞ control synthesis problems convex

In this paper, we present some computationally tractable conditions which make the constantly scaled H_∞ control synthesis problem convex. If one of the conditions proposed in this paper holds, the constantly scaled H_∞ control synthesis problem can be solved efficiently as an LMI problem. The results presented here include the existing results such as the state feedback and the full information problems as special cases. In addition, the results are generalized to the case that some of state variables are exactly available. Owing to this generalization, a larger class of problems can be reduced to convex problems, while reduced order controllers can be obtained. Copyright © 2001 John Wiley & Sons, Ltd.     

Fundamental research on thermal plasma technology for treatment of low-level radioactive solid waste

The technology for treatment of low-level radioactive solid waste generated in nuclear power plants is expected to be established. The main problems are volume reduction and stabilization of radionuclides acceptable for final disposal. Thermal plasma technology offers advantages for such waste treatment because of the easy supply of heat at high temperature independent of chemical and physical properties of the waste. New, noncontaminated waste, such as metallic, inorganic and combustible materials, have been melted in a crucible furnace. A transferred-type of a dc plasma torch with a solid electrode was used as heat source and rated up to 50 kW. The main results obtained are as follows:

• 1 (1) Metallic and inorganic materials can be melted and vitrified. Combustible materials can be pyrolyzed. Consequently, high-volume reduction rates can be attained.
• 2 (2) Compressive strength of solidified products is more than twice as great as that of cement composites used for solidification of the liquid waste. Leaching rate of main components of the slag layer is in the same order of that of the high-level radioactive waste glass.
• 3 (3) To obtain a guiding principle for design of an off-gas treating system, compositions of the off-gas and properties of the dust entrained in the off-gas are clarified.

From these results, technical prospects so that plasma heating technology can be applied for treatment of low-level radioactive solid waste have been obtained.     

Substitution of Sodium and Silicon in Tricalcium Aluminate

Four types of tricalcium aluminate solid solutions with different concentrations of Na₂O and SiO₂ were prepared and examined using an electron probe microanalyzer. The atomic ratios, including those determined in a previous study, were derived from the oxide compositions and provided excellent correlations between Ca and Na + Si (i.e., Ca = 3.003 − 0.48[Na + Si]), and Al and Si (Al = 1.997 − 1.02Si). Because the replacement reactions, Ca²⁺↔ 2Na⁺ and Ca²⁺+ 2Al³⁺↔ 2Si⁴⁺, independently occur within the same crystal, these reactions have been simply combined together to generate a new formula, Na_{2 x} Ca_{3− x − y} (Al_{1− y} Si _y )₂O₆, where x is the amount of Ca substituted by Na, and y is the amount of Al substituted by Si. This formula leads to the equations Ca = 3 − 0.5[Na + Si] and Al = 2 − Si, which nicely account for the constrained chemical variation of the actual solid solutions with 0 ≤ x < 0.049 and 0 ≤ y < 0.073.     

A level set-based topology optimization incorporating arbitrary Lagrangian Eulerian method for wavelength filter using extraordinary optical transmission

This paper deals with structural optimization for designing periodic structures in a hole array wavelength filter. The hole array wavelength filter that consists of metallic thin film and dielectric enables to transmit narrow bandwidth light. It is known that transmission spectrum can be changed not only by the periodicity of hole array but also by the shape of holes. For optimizing the hole shape, the level set method is used in this study. In the ordinary level set method, the boundaries are implicitly expressed by the zero level set of a scalar function, called the level set function, within a fixed mesh. Therefore, the material interpolation becomes numerically awkward within the elements across the implicit zero level set because those elements inevitably take on intermediate material properties even if the boundary of zero level set are mathematically clear. As the result, the optimization is likely to yield wrong solution. Here, a new level set optimization method incorporating Arbitrary Lagrangian Eulerian method is proposed to eliminate intermediate values on the interfaces perfectly. As a result, the proposed method can successfully perform the structural optimization of hole shape without intermediate values.     

A new current balancer in single‐phase three‐wire secondary distribution feeders using the correlation coefficients

This paper proposes a new current balancer in single‐phase three‐wire secondary distribution systems using the correlation coefficients. The components of the load currents correlative to the primary side voltage waveform, which correspond to the active currents, are detected in each feeder, then the nonactive and unbalanced‐active components are compensated on the source side. The balanced currents with unity power factor are obtained in each feeder. The basic principle of the proposed method is discussed in detail, and then confirmed by digital computer simulation. A prototype experimental system is constructed and tested. Experimental results demonstrate that the balanced source currents with unity power factor are obtained in spite of unbalanced load currents. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(1): 50–58, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20843     

Effectiveness and biocompatibility of a novel biological adhesive application for repair of meniscal tear on the avascular zone

We have investigated the effectiveness and safety of a newly developed biological adhesive for repair of meniscal tear. The adhesive was composed of disuccinimidyl tartrate (DST) as a crosslinker and human serum albumin (HSA) as a hardener. To determine adequate concentration, bonding strength was measured using a tensiometer 5 min after applying the adhesive on the avascular zone tear of porcine meniscus; it was compared with the strengths of commercially available cyanoacrylate-based and fibrin-based adhesives. In vivo examination was performed using Japanese white rabbits, creating longitudinal tears on the avascular zone of meniscus and applying DST–HSA adhesive. Three months after operation the rabbits were sacrificed and tension test and histological evaluation were performed. Bonding strength was measured in three porcine meniscus groups: (i) only suturing, (ii) suturing after applying the adhesive on surface and (iii) suturing using an adhesive-soaked suture. The optimum concentrations were 0.1 mmol of DST and 42 w/v% of HAS. Bonding strength was greatest with cyanoacrylate-based adhesive, followed by DST–HSA adhesive, and fibrin-based adhesive. No inflammation was observed in the synovium or surrounding tissues 3 months after using the DST–HSA adhesive. Bonding strength was greatest with DST–HSA adhesive-soaked suturing group (77 ± 6 N), followed by suturing only group (61 ± 5 N) and surface adhesive application group (60 ± 8 N). The newly developed DST-HSA adhesive is considered safe and may be effective in enforcement of bonding of avascular zone tear of the meniscus.