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.     

Adjunctive Application of Antimicrobial Photodynamic Therapy in Nonsurgical Periodontal Treatment: A Review of Literature

Periodontal disease is caused by dental plaque biofilms, and the removal of these biofilms from the root surface of teeth plays a central part in its treatment. The conventional treatment for periodontal disease fails to remove periodontal infection in a subset of cases, such as those with complicated root morphology. Adjunctive antimicrobial photodynamic therapy (aPDT) has been proposed as an additional treatment for this infectious disease. Many periodontal pathogenic bacteria are susceptible to low-power lasers in the presence of dyes, such as methylene blue, toluidine blue O, malachite green, and indocyanine green. aPDT uses these light-activated photosensitizer that is incorporated selectively by bacteria and absorbs a low-power laser/light with an appropriate wavelength to induce singlet oxygen and free radicals, which are toxic to bacteria. While this technique has been evaluated by many clinical studies, some systematic reviews and meta-analyses have reported controversial results about the benefits of aPDT for periodontal treatment. In the light of these previous reports, the aim of this review is to provide comprehensive information about aPDT and help extend knowledge of advanced laser therapy.     

Estrogen Stimulates Proliferation and Differentiation of Neural Stem/Progenitor Cells through Different Signal Transduction Pathways

Our previous study indicated that both 17β-estradiol (E2), known to be an endogenous estrogen, and bisphenol A (BPA), known to be a xenoestrogen, could positively influence the proliferation or differentiation of neural stem/progenitor cells (NS/PCs). The aim of the present study was to identify the signal transduction pathways for estrogenic activities promoting proliferation and differentiation of NS/PCs via well known nuclear estrogen receptors (ERs) or putative membrane-associated ERs. NS/PCs were cultured from the telencephalon of 15-day-old rat embryos. In order to confirm the involvement of nuclear ERs for estrogenic activities, their specific antagonist, ICI-182,780, was used. The presence of putative membrane-associated ER was functionally examined as to whether E2 can activate rapid intracellular signaling mechanism. In order to confirm the involvement of membrane-associated ERs for estrogenic activities, a cell-impermeable E2, bovine serum albumin-conjugated E2 (E2-BSA) was used. We showed that E2 could rapidly activate extracellular signal-regulated kinases 1/2 (ERK 1/2), which was not inhibited by ICI-182,780. ICI-182,780 abrogated the stimulatory effect of these estrogens (E2 and BPA) on the proliferation of NS/PCs, but not their effect on the differentiation of the NS/PCs into oligodendroglia. Furthermore, E2-BSA mimicked the activity of differentiation from NS/PCs into oligodendroglia, but not the activity of proliferation. Our study suggests that (1) the estrogen induced proliferation of NS/PCs is mediated via nuclear ERs; (2) the oligodendroglial generation from NS/PCs is likely to be stimulated via putative membrane-associated ERs.     

Substituent effects on the photofading of disperse azo dyes on poly(ethylene terephthalate) substrate

The relationships between the chemical structures and oxidative fading of the disperse azo dyes, p‐nitrophenylazo‐ and benzothiazoleazo‐anilines, on poly(ethylene terephthalate) substrate are discussed in terms of the parameters k_0,i (rate constants of reaction towards ¹O₂) and f_i (photosensitivity), the molecular parameters of molecular orbital theory and substituents in the diazo and coupling components, on the assumption that the initial rates of oxidative fading are proportional to the product of k_0,i and f_i. 2‐Methoxy‐5‐acetylamino‐N‐substituted aniline couplers exhibited large f_i values. 2‐Chloro and 4‐nitro substituents of aniline diazo components exhibited small f_i values or high quantum yields of internal conversion, while 4‐nitro substituent did not. A close correlation between N‐substituents and light fastness, proposed by Müller and supplemented by Dawson, demonstrates the applicability of frontier orbital theory, through the highest occupied molecular orbital (HOMO) energy of the dyes, to the analysis of oxidative fading. Dyes with N‐2‐cyanoethyl substituents, which gave a lower HOMO energy, also exhibited superior light fastness compared with N‐2‐hydroxyethyl substituents.     

Electron Density Distribution in Mn<Subscript>4</Subscript>Si<Subscript>7</Subscript>

Single crystal diffraction measurements were successfully carried out for spherical fine grains grown as single crystals of 0.05–0.2 mm in diameter. Local modulations in the silicon layers were also observed by means of high-resolution electron microscopy. The metallic tin–flux technique was used for crystal growth. The Fourier synthesis and maximum entropy method (MEM) were applied to x-ray diffraction data to obtain electron density distribution maps. Mn₄Si₇ is one of the most promising p-type thermoelectrics useable from 400 K to 700 K. The crystal structure is described in terms of a chimney-ladder structure. The doping effect, by which the system becomes n-type and a structure modulation occurs, was reported by our group previously. The resultant electron density maps were compared with those from the band calculation. The MEM calculation shows the displacement of silicon positions.     

Effect of Surface Treatment on the Selective Photocatalytic Oxidation of Benzyl Alcohol into Benzaldehyde by O2 on TiO2 Under Visible Light

The photocatalytic oxidation of benzyl alcohol into benzaldehyde proceeded with high conversion and selectivity on a TiO₂ photocatalyst by O₂ under visible light irradiation. Surface complex formed by the interaction of benzyl alcohol with the Ti sites and/or surface OH groups of TiO₂ play an important role in the absorption of visible light and unique selective photocatalytic reaction.     

Role of protein kinase Cbeta in rhythmic contractions of human pregnant myometrium

To assess the role of protein kinase Cbeta (PKCbeta) in human myometrial contractions during pregnancy, we evaluated the effect of a PKCbeta inhibitor (LY333531) on the pregnant and nonpregnant myometrial contractions and compared the level of PKCbeta in the pregnant myometrium with that in the nonpregnant myometrium. The effects of LY333531 on the myometrial contractions were examined by measuring contractile activity (frequency and amplitude). PKCbeta in human myometrium was assessed at mRNA level using real-time PCR method. The characteristics of contractile activity were different between the pregnant and the nonpregnant myometrium. The amplitude of rhythmic contractions in the preterm and term myometrium was increased 2- to 2.5-fold when compared with that in the nonpregnant myometrium, but the frequency of rhythmic contractions was decreased by about half. LY333531 (10(-6) M) reduced the increased amplitude in the preterm and term myometrium by about 50%, and the inhibitory effects of LY333531 in the pregnant myometrium were significantly greater than that in the nonpregnant myometrium (about 50 vs 25%). However, the frequency in the pregnant and nonpregnant myometrium was not influenced by LY333531. Real-time PCR revealed a significant, five- to sevenfold increase in the expression of PKCbeta mRNA in the preterm and term myometrium when compared with the nonpregnant myometrium. These findings suggest that the increased amplitude of human myometrial contractions during pregnancy is related to the increased level of PKCbeta. A PKCbeta inhibitor may reduce preterm uterine contractions and prevent preterm delivery.     

A genetic algorithm with local search using activity list characteristics for solving resource‐constrained project scheduling problem with multiple modes

In this paper, we aim to solve the problem of resource‐constrained project scheduling with multiple modes (rc‐PSP/mM), in which multiple execution modes are available for each of the project's activity and with minimization of makespan as objective. We present a new genetic algorithm approach in order to solve this problem. In this procedure, we propose a new mutation operator that exploits a critical path and two new local search procedures, i.e. critical path improvement local search (cpiLS) and iterative forward/backward local search (ifbLS), using activity list characteristics. The cpiLS reduces the critical path and the ifbLS improves resource allocation of the schedule of rc‐PSP/mM. Also, to evaluate the proposed approach, we compare the results of the computational experiment on certain standard project instances with the several competing heuristic procedures presented in the literature, and it has been revealed that our procedure is one of the most competitive among the algorithms. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.