Creation of Ferroelectric, Single-Crystal Architecture in Sm0.5La0.5BGeO5 Glass

Using a novel, selective heating by Nd:YAG laser, a single-crystal architecture is created in a model glass system, Sm_0.5La_0.5BGeO₅, which devitrifies congruently into a ferroelectric phase of the same composition as the parent glass. The Sm³⁺ ions in glass absorb the light and heat the matrix locally resulting in devitrification. Initially, a polycrystalline spot is formed. However, with optimum laser power, scanning speed, and the depth of focus, one of the grains acts as the seed for further growth as a single crystal. By programming the relative displacement of the glass with respect to laser spot, desired single ferroelectric crystal architecture is created. The optical functionalities (guiding of light and second harmonic generation) of the architectures are shown, which demonstrate the viability of this method for constructing active elements in optical integrated circuits. The single-crystal nature of the architecture is confirmed from the electron backscattered diffraction results.     

New bleeding model of additives in a polypropylene film under atmospheric pressure II

Many additives are commercially used to add more favorable qualities to films. The bleeding process by which the additive in a film comes to the surface is considered. A new bleeding model of additives in a polypropylene film under atmospheric pressure was investigated. Solubility and diffusion are found to be important for explaining this bleeding process. It was found that the experimental results were explained more precisely by assuming a two‐step transport process between the crystalline regions and the amorphous ones. The solubilities and diffusion coefficients of UV‐stabilizers such as 2‐(2H‐benzotriazol‐2‐yl)‐4‐(1,1,3,3‐tetramethylbutyl)phenol and 2‐(2H‐benzotriazol‐2‐yl)‐4‐methylphenol were determined at 40°C. The difference between the saturation solubilities and the diffusion coefficients of UV‐stabilizers was discussed by comparing with the results of molecular dynamics (MD) simulation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Electrolytic removal of ammonia from brine wastewater: scale‐up,operation and pilot‐scale evaluation

Brine wastewater with a high ammonia content from an iodine processing plant (commonly called kansui in Japan) was treated by electrolysis. The system, which can be considered as an indirect electrolytic treatment process, generates chlorine at the anodes and initiates the formation of mixed oxidants like hypochlorous acid. The oxidants then act as agents for ammonia destruction. Laboratory‐scale experiments showed that high ammonia concentrations (as much as 200 mg dm^?3) could be completely removed within a few minutes, and could be considered a good alternative for efficient ammonia removal from saline wastewaters. From laboratory‐scale experiments in the batch and continuous modes, the charge dose was analyzed and used as the operating and scale‐up factor. The value of the charge dose was not severely affected by changes in operating conditions such as electrode spacing and temperature. The charge dose from batch and continuous runs was found to be in the range of 23 C (mg NH₄‐N removed)^?1 to 29 C (mg NH₄‐N removed)^?1. Using the charge dose obtained from laboratory‐scale continuous electrolysis experiments as the scale‐up factor, a pilot‐scale reactor was designed, and the operating conditions were calculated. In the pilot‐scale reactor tests at different flow rates, the effluent ammonia concentrations were reasonably close to the calculated values predicted from the charge dose equation. Copyright © 2004 Society of Chemical Industry     

Nondestructive inspection of thermal barrier coating of gas turbine high temperature components

A thermal barrier coating (TBC) is applied to high‐temperature components in gas turbines, and consists of a ceramic topcoat and a metallic bondcoat. Various kinds of TBC degradation and damage occur in high‐temperature components during service, such as topcoat thinning, topcoat delamination, and formation of a thermally grown oxide (TGO) layer below the topcoat, each of which can be examined using a suitable nondestructive inspection technique. Topcoat thinning can be detected by topcoat thickness measurement using terahertz waves, which are electromagnetic waves in the frequency region between optical and radio waves. The measurement resolution is about 10 μm, which is comparable to microscopic observation of the cross section in destructive inspection. Topcoat delamination can be detected by active thermography, in which the topcoat surface is scanned by a heating laser and the surface temperature distribution is measured by a thermal infrared camera. The combination of temperature peak and residual thermal image detection is effective in eliminating false detection. The TGO layer can be detected using photoluminescence, in which the Cr³⁺ ions included as an impurity in Al₂O₃ are detected. Since delamination tends to occur at locations at which the TGO layer has grown, TGO layer detection provides an effective method to select regions where delamination has occurred or is likely to occur. An inspection flow based on these techniques is proposed, which is expected to aid the establishment of condition‐based maintenance strategies of high‐temperature components. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Comparison of particle-phase polycyclic aromatic hydrocarbons and their variability causes in the ambient air in Ho Chi Minh City, Vietnam and in Osaka, Japan, during 2005-2006

A comparative study of polycyclic aromatic hydrocarbons (PAHs) associated with particulate matter (TSP) in the ambient air in an urban area in Ho Chi Minh City, Vietnam and in Osaka, Japan was carried out from 2005 to 2006. The objective of this study was to investigate the environmental levels, emission sources, seasonal variations and health risk of eleven PAHs in the two cities, especially Ho Chi Minh City where air pollution is becoming a serious concern. The results showed that the concentrations of TSP and total PAHs were significantly higher in Ho Chi Minh City than levels in Osaka. The concentrations of 5- and 6-ring PAHs (BeP, BbF, BkF, BaP, BghiP and InP) were much higher in TSP samples in Ho Chi Minh City than in Osaka, accounting for 82% and 51% of total PAHs, respectively. These PAHs are known to be highly carcinogenic and mutagenic in humans. Vehicular emission is suggested as one of the main pollution sources of PAHs in both cities. Motorcycles and gasoline automobiles are suggested as the main emission sources of PAHs in Ho Chi Minh City, whereas diesel automobiles are the primary source in Osaka. Seasonal variations of PAHs were observed in this study; higher concentrations of PAHs were found in the rainy season (May-December) and lower concentrations corresponded to the dry season (February-April) in Ho Chi Minh City, while higher concentrations of PAHs were observed in the winter (November-January) in Osaka. The number of sunshine hours was an important meteorological factor affecting seasonal variations of PAHs in Ho Chi Minh City, while the temperature was a main factor causing the variations of PAHs in Osaka. The high BaP equivalent concentration of 5- and 6-ring PAHs even in the ambient air is an alarming signal for harmfulness to human health and environmental quality in Ho Chi Minh City.     

Effect of mean stress on fatigue properties of 1800 MPa-class spring steels

Fatigue tests were conducted for 1800 MPa-class spring steels at various stress ratios. For comparison, similar fatigue tests were conducted for conventional steels whose tensile strength was lower than 1200 MPa. The spring steels exhibited fish-eye fractures, and the origins of these fractures were oxide, TiN and the matrix itself. In contrast, the conventional steels never exhibited fish-eye fractures. The fatigue strength of these steels decreased monotonously as the stress ratio increased, when the fatigue strength was evaluated in terms of stress amplitude. However, the fatigue strength degradation was less than that expected from a modified-Goodman line, and the best fit line was obtained by connecting the fatigue limit at zero mean stress to true fracture strength instead of tensile strength. This research also reviewed application of a power low to the stress ratio effect evaluation. In these results, the difference between the spring and conventional steels was negligible.     

Hydrothermal Synthesis of Oriented Anatase Films Consisting of Columnar Aggregates and Their Wetting Properties

We hydrothermally synthesized anatase films on Ti substrates from transparent aqueous solutions of layered titanate colloids. The morphology and wetting properties of the films were examined. The films consisted of columnar aggregates grown on the Ti substrates, which resulted in high orientation. Randomly oriented films were obtained when alumina was used as a substrate, whereas the sol–gel precoating of a titanium oxide (TiO₂) layer on alumina substrates resulted in similar orientation as that of the films on Ti substrates. Thus, the presence of TiO₂ on the substrate surface plays an important role in the orientation of columnar aggregates. The columnar aggregates were similar in microstructure to the arms of a type of six-pointed star-like anatase aggregate synthesized hydrothermally from the same reaction solutions. They were composed of twins of tapered anatase nanocrystals, which provided a rough film surface. The film surface was highly hydrophilic and oleophilic due to the nanoscale roughness even when the film was not irradiated with UV light.     

Color control of Japanese soy sauce (shoyu) using membrane technology

The present study systemically decolorized soy sauce using a membrane process to analyze the separation mechanism. An ultrafiltration (UF) membrane (NTU-2120) exhibited only slight decolorization ability. A nanofiltration (NF) membrane with a lower molecular weight cut-off and produced by sulfonated polysulfone (NTR-7400 series) rather than polyvinyl alcohol/polyamide (NTR-7250) had higher decolorization ability. The NF membranes rejected total nitrogen by 17–24%, unsalted soluble solid content by 24–32%, reducing sugar by 25–43%, and amino acids by 10–25%. The NTR-7400 series membrane rejected lactic acid by 6–9%, and pyroglutamic acid by 11–21%; other quality indexes were maintained. In the NF membrane processes, higher rejection of acidic amino acids than neutral and base amino acids was observed. The separation performance was governed by the electrical effect as well as the sieve effect. Soy sauce color could be controlled by blending NF membrane-processed soy sauce with feed soy sauce. Color can be matched to preference in accordance with dishes by suitably blending NF membrane-processed soy sauce with feed soy sauce.     

Effects of casting solvents on characteristics of organic EL devices containing poly(l-glutamate) as hole-transport material

The characteristics of EL devices containing α-helical poly(l-glutamate) and having a carbazole side chain (PCELG) were found to strongly depend on the casting solvents. Among EL devices fabricated using chlorine-containing casting solvents such as 1,2-dichloroethane (DCE), 1,1,2,2-tetrachloroethane (TCE), chloroform (CHCl₃), and monochlorobenzene (?-Cl), the EL device fabricated using the DCE solvent exhibited the maximum luminance (65.8 cd/m²). The difference between the threshold voltages of the devices ranged up to 6.0 V, despite their fabrication by using solutions with the same composition ratio. The maximal efficiency of the devices fabricated using the DCE solvent was found to be 20 times greater than that of the devices fabricated using TCE solvents. A comparison of the current densities and voltages among devices fabricated using different casting solvents at their maximal efficiencies showed that the maximal efficiencies tended to significantly increase in the order TCE < CHCl₃ < DCE solvents at similar voltages (～15 V), despite a lowering of the current density. The current density was considered to be directly related to the number of carriers injected into the device. The above-mentioned observations suggested that the maximal efficiency in these devices was not the hole and electron injection efficiencies, but the values of some parameters subsequent to carrier injection, such as the recombination rate, amount of excitons generated, and the diffusion length.     

The Wulff Shape of Alumina: II, Experimental Measurements of Pore Shape Evolution Rates

The rate at which a facetted tetragonal cavity of nonequilibrium shape approaches a cubic equilibrium (Wulff) shape via surface diffusion was modeled. The shape relaxation rate of a facetted "stretched cylinder" was also modeled. For the first geometry, only an approximate solution based on linearizing the mean potential difference between the source and sink facets was obtained. For the stretched cylinder, both an approximate and an exact solution can be obtained; the approximate solution underestimates the evolution rate by a factor of ∼2. To assess the applicability of the models, nonequilibrium shape pores of identical initial geometry (∼20 μm × 20 μm × 0.5 μm) were introduced into (0001), {10[Onemacr]2}, {1120}, and {100} surfaces of sapphire single crystals using microfabrication techniques, ion-beam etching, and hot pressing. The large (∼20 μm × 20 μm) faces of the pore are low-index surfaces whose nature is dictated by the wafer orientation. A series of anneals was performed at 1900°C, and the approach of the pore shape to an equilibrium shape was monitored. The kinetics of shape evolution are highly sensitive to the crystallographic orientation and stability of the low-index surface that dominates the initial pore shape. The measured variations of the pore aspect ratio were compared to those predicted by the kinetic model. The observations suggest that when the initial bounding surface is unstable, shape relaxation may be controlled by diffusion. However, surface-attachment-limited kinetics (SALK) appears to play a major role in determining the pore shape evolution rate in cases where the initial bounding surfaces have orientations that are part of the Wulff shape.