Comparison of Oxidation and Thermal Shock Performance of Thermal Barrier Coatings

Operating temperatures in gas turbine engines have reached to 1200°C with the latest developments in coating technology. Thermal shock and furnace oxidation tests are widely used to determine thermal barrier coating (TBC) performance and its durability in aircraft applications. This paper presents the results of thermal shock and furnace oxidation tests, carried out with regard to the microstructure and TGO (thermally grown oxide) growth behavior of TBC systems. Isothermal oxidation behavior of TBCs was evaluated through examination of microstructure, formation, and growth behavior of TGO layers at 1200°C for different time periods in furnace oxidation tests. On the other hand, thermal shock behavior of TBC was evaluated through examination of its durability at 1200°C with thermal shock test, which was carried out until the coating failure became visible. The relationship between the TGO growth and oxidation behavior was discussed using furnace oxidation test results.     

Inhibitory effects of selected pesticides on peroxidases purified by affinity chromatography

The objective of this study was to determine the in vitro inhibition effects of seven commonly used pesticides including 2,4-d-acid dimethylamine, fenoxaprop-p-ethyl, glyphosate isopropylamine, haloxyfop-p-methyl, cypermethrin, λ-cyhalothrin, and dichlorvos on the peroxidase purified from turnip (Brassica rapa L.) and black radish (Raphanus sativus L.) using 4-amino benzohydrazide affinity column chromatography. The purification factors for the turnip and black radish peroxidases were found to be 263.29-fold (with a yield of 12.89%) and 36.20-fold (with a yield of 6.90%), respectively. Among these compounds, λ-cyhalothrin showed the strongest inhibitory effect against turnip peroxidase (K_i: 1.23 × 10^?2 ± 0.21 × 10^?2 mM) as noncompetitive inhibition. On the other hand, cypermethrin demonstrated the highest inhibition effect against black radish peroxidase (K_i: 2.14 × 10^?2 ± 0.08 × 10^?2 mM) as competitive inhibition.     

Mechanical and thermal properties of wood‐plastic composites reinforced with hexagonal boron nitride

Mechanical, thermal, and morphological properties of injection molded wood‐plastic composites (WPCs) prepared from poplar wood flour (50 wt%), thermoplastics (high density polyethlyne or polypropylene) with coupling agent (3 wt%), and hexagonal boron nitride (h‐BN) (2, 4, or 6 wt%) nanopowder were investigated. The flexural and tensile properties of WPCs significantly improved with increasing content of the h‐BN. Unlike the tensile and flexural properties, the notched izod impact strength of WPCs decreased with increasing content of h‐BN but it was higher than that of WPCs without the h‐BN. The WPCs containing h‐BN were stiffer than those without h‐BN. The tensile elongation at break values of WPCs increased with the addition of h‐BN. The differential scanning calorimetry (DSC) analysis showed that the crystallinity, melting enthalpy, and crystallization enthalpy of the WPCs increased with increasing content of the h‐BN. The increase in the crystallization peak temperature of WPCs indicated that h‐BN was the efficient nucleating agent for the thermoplastic composites to increase the crystallization rate. POLYM. COMPOS., 35:194–200, 2014. © 2013 Society of Plastics Engineers     

An efficient initial ranging algorithm for WiMAX (802.16e) OFDMA

Ranging is one of the most important processes in the mobile WiMAX standard. Power adjustment, timing offset estimation, and synchronization between a base station (BS) and all users within a cell are done through the ranging process referred to as initial ranging. In this paper, we discuss the details of initial ranging together with some of the proposed algorithms, as well as a novel algorithm to carry out a successful ranging process. Performance curves and computational complexity comparisons are presented. The system performance is evaluated for both additive white Gaussian noise (AWGN) channels and practical multipath fading channels with multiuser interference. It is shown that the proposed algorithm offers a reduced complexity ranging method that can be employed in practical WiMAX-based BSs.     

Triangular prisms for edge-based vector finite element analysis ofconformal antennas

This paper deals with the derivation of the edge-based shape functions for the distorted triangular prism and their applications for the analysis of doubly curved conformal antennas in the context of the finite element method (FEM). Although the tetrahedron is often the element of choice for volume tessellation, mesh generation using tetrahedra is cumbersome and the central processing unit (CPU) intensive. On the other hand, the distorted triangular prism allows for meshes which are unstructured in two dimensions and structured in the third dimension. This leads to substantial simplifications in the meshing algorithm, and many conformal printed antenna and microwave circuit geometries can be easily tessellated using such a mesh. The new edge-based shape functions are first validated by computing the eigenvalues of three different cavities (rectangular, cylindrical, and pie-shell). We then proceed with their application to computing the input impedance of conformal patch antennas on planar, spherical, conical, and other doubly curved (ogival) platforms, where the FEM mesh is terminated using an artificial absorber applied conformal to the platform. Use of artificial absorbers for mesh termination avoids introduction of Green's functions and, in contrast to absorbing boundary conditions, a knowledge of the principal radii of curvature of the closure's boundary is not required     

A spin wave resonance study on reentrant Au77Fe23 films

Thin films prepared by both flash and slow evaporation of the bulk Au₇₇Fe₂₃ alloy have been studied by electron spin resonance (ESR) technique at the temperature range between 77–300 K. A series of spin wave resonance (SWR) peaks were observed at all temperatures when the external de magnetic field is applied along the directions lying in a small angular interval with respect to the film normal. The classical spin wave model has been used to analyze the experimental data. The magnetic parameters, such as exchange stiffness constant, the effective bulk and the surface anisotropy energy parameters of the system have been derived as a function of temperature. While the easy plane surface anisotropy almost remains constant, considerable increments were found in the exchange parameter, the magnetization and the linewidth with decreasing temperature. The SWR linewidths for the films obtained by slow evaporation at higher substrate temperatures are noticeably smaller compared to those of the film prepared by flash evaporation technique.     

A Statistical Analysis of the Robustness of Alternate Genetic Coding Tables

The rules that specify how the information contained in DNA is translated into amino acid “language” during protein synthesis are called “the genetic code”, commonly called the “Standard” or “Universal” Genetic Code Table. As a matter of fact, this coding table is not at all “universal”: in addition to different genetic code tables used by different organisms, even within the same organism the nuclear and mitochondrial genes may be subject to two different coding tables. Results In an attempt to understand the advantages and disadvantages these coding tables may bring to an organism, we have decided to analyze various coding tables on genes subject to mutations, and have estimated how these genes “survive” over generations. We have used this as indicative of the “evolutionary” success of that particular coding table. We find that the “standard” genetic code is not actually the most robust of all coding tables, and interestingly, Flatworm Mitochondrial Code (FMC) appears to be the highest ranking coding table given our assumptions. Conclusions It is commonly hypothesized that the more robust a genetic code, the better suited it is for maintenance of the genome. Our study shows that, given the assumptions in our model, Standard Genetic Code is quite poor when compared to other alternate code tables in terms of robustness. This brings about the question of why Standard Code has been so widely accepted by a wider variety of organisms instead of FMC, which needs to be addressed for a thorough understanding of genetic code evolution.     

Metamorphism in culture and housing desing: Turkey as an example

Lawrence maintains about all architectural environments and housing that, they are both in a relationship with culture and they are a total configuration of social, demographical, psychological, human behavioral and environmental structure. Moreover, in analyzing this complex structure, he emphasizes to examine it within two perspectives: design-meaning and use. Consequently, the basic components, which affect housing design, are classified in three main topics: cultural, social, and psychological. In the light of Lawrence's ideas, under the topic of the role of culture and tradition in the development of housing, this paper aims to define the basic Turkish traditional housing principles with slogans and important examples. In this content, cultural, social and psychological components in traditional Turkish houses are held under the heading of the development of traditional Turkish house. The organization rules, the effects of the basic psycho-social components…etc., and the presence of these principles are criticized with Turkish housing examples before and after 1980. The chosen period in this study is not coincidental. The aim of choosing the periods before and after 1980 has a special meaning in Turkey's economic, politic and social life. Choosing these two basic periods, will not only point out the changes—like a metamorphism—in cultural life, but in architectural needs in Turkish houses. Therefore, in the aim of analyzing cultural changes and their effects on housing design, the architectural meanings in the elements of Turkish houses are put forward in details, in order to make some estimation for the future of changing Turkish architectural life.     

Critical appraisal of respirometric methods for metal inhibition on activated sludge

This paper evaluates the merit of oxygen uptake rate measurements for the assessment of metal inhibition on activated sludge. For this purpose, experiments are conducted to calculate EC50 levels of nickel and hexavalent chromium using the ISO 8192 procedure, yielding results that are highly variable and difficult to correlate, depending on the type of substrate and the initial food to microorganism ratio. Similar experiments based on continuous respirometric measurements to give the entire oxygen uptake rate profile provide a much better insight on the impact of inhibition on different biochemical processes taking place in the reactor. The results indicate that percent reduction of the amount of dissolved oxygen utilized after an appropriate reaction time is a much better index for the assessment of the inhibitory effects.