Low-cost nanostructured Fe2O3-based composite catalysts synthesized by mechanical milling for CO oxidation reaction

In this work, the catalytic properties of low-cost nanostructured iron oxide have been improved by the mechanical milling method through combination with copper and cobalt oxide. Synthesized catalysts were characterized by X-ray diffraction, transition electron microscopy, and Brunauer–Emmet–Teller techniques. Also, the catalytic activity and stability of the powders for CO oxidation reaction were investigated. Results indicated that the catalytic activity of the powders has significantly improved after mechanical milling. Minimum complete conversion temperatures for Co–Fe and Cu–Fe composite oxide catalysts were around 245 and 275°C, respectively. No decline in the activity of the catalysts was observed during the long-term stability test. Furthermore, catalytic activity of the composite powders, especially Co–Fe improves at subsequent cycles. In general, cycle durability, stability at high temperature and reaction rate of the iron oxide powder has been improved using it as Cu–Fe and Co–Fe oxide composites.     

Quality enhancement of AZO thin films at various thicknesses by introducing ITO buffer layer

Due to the simultaneously superior optical transmittance and low electrical resistivity, transparent conductive electrodes play a significant role in semiconductor electronics. To enhance the electrical properties of these films, one approach is thickness increment which degrades the optical properties. However, a preferred way to optimize both electrical and optical properties of these layers is to introduce a buffer layer. In this work, the effects of buffer layer and film thickness on the structural, electrical, optical and morphological properties of AZO thin films are investigated. Al-doped zinc oxide (AZO) is prepared at various thicknesses of 100 to 300 nm on the bare and 100 nm-thick indium tin oxide (ITO) coated glass substrates by radio frequency sputtering. Results demonstrate that by introducing ITO as a buffer layer, the average values of sheet resistance and strain within the film are decreased (about 76 and 3.3 times lower than films deposited on bare glasses), respectively. Furthermore, the average transmittance of ITO/AZO bilayer is improved nearly 10% regarding single AZO thin film. This indicates that bilayer thin films show better physical properties rather than conventional monolayer thin films. As the AZO film thickness increases, the interplanar spacing, d₍₀₀₂₎, strain within the film and compressive stress of the film in the hexagonal lattice, decreases indicating the higher yield of AZO crystal. Moreover, with the growth in film thickness, carrier concentration and optical band gap (E_g) of AZO film are increased from 4.62?×?10¹⁹ to 8.21?×?10¹⁹ cm^?3 and from 3.55 to 3.62 eV, respectively due to the Burstein-Moss (BM) effect. The refractive index of AZO thin film is obtained in the range of 2.24–2.26. With the presence of ITO buffer layer, the AZO thin film exhibits a resistivity as low as 6?×?10^?4 Ω cm, a sheet resistance of 15 Ω/sq and a high figure of merit (FOM) of 1.19?×?10⁴ (Ω cm)^?1 at a film thickness of 300 nm. As a result, the quality of AZO thin films deposited on ITO buffer layer is found to be superior regarding those grown on a bare glass substrate. This study has been performed over these two substrates because of their significant usage in the organic light emitting diodes and photovoltaic applications as an enhanced carrier injecting electrodes.     

An efficient mesh router nodes placement in wireless mesh networks based on moth-flame optimization algorithm

One of the most challenging tasks is deploying a wireless mesh network backbone to achieve optimum client coverage. Previous research proposed a bi-objective function and used a hierarchical or aggregate weighted sum method to find the best mesh router placement. In this work, to avoid the fragmented network scenarios generated by previous formulations, we suggest and evaluate a new objective function to maximize client coverage while simultaneously optimizing and maximizing network connectivity for optimal efficiency without requiring knowledge of the aggregation coefficient. In addition, we compare the performance of several recent meta-heuristic algorithms: Moth-Flame Optimization (MFO), Marine Predators Algorithm (MPA), Multi-Verse Optimizer (MVO), Improved Grey Wolf Optimizer (IGWO), Salp Swarm Algorithm (SSA), Grey Wolf Optimizer (GWO), Whale Optimization Algorithm (WOA), Harris Hawks Optimization (HHO), Particle Swarm Optimization (PSO), Sine Cosine Algorithm (SCA), and Slime Mould Algorithm (SMA). We empirically examined the performance of the proposed function using different settings. The results show that our proposed function provides higher client coverage and optimal network connectivity with less computation power. Also, compared to other optimization algorithms, the MFO algorithm gives higher coverage to clients while maintaining a fully connected network.     

Fuzzy discontinuous term for a second order asymptotic DSMC: An experimental validation on a chemical reactor

In this work, a second order asymptotic discrete sliding mode control with a fuzzy supervised discontinuous term is proposed. The on line variation of the discontinuous term amplitude enhances the convergence rapidity of the sliding function and reduces the chattering phenomenon. These improvements are shown by a numerical simulation and by a real time temperature control of a chemical reactor. Good performances in terms of chattering suppression and reaching phase duration's reduction are noted. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Antimicrobial and antioxidant properties of burgers with quinoa peptide-loaded nanoliposomes

This study was aimed to examine the antioxidant (thiobarbituric acid reactive substances [TBARS], peroxide value [PV], and as well as antimicrobial (total bacterial count, Staphylococcus aureus [S. aureus], mold and yeast counts) activities and spoilage indices (total volatile base nitrogen [TVB-N]) of quinoa peptide-loaded liposomes incorporated into burger during 12 days of refrigerated storage. Among four prepared batches, the lowest TBARS, PV, and TVB-N values (0.281 ± 0.05 mg MDA/kg, 3.25 ± 0.34 mEq/kg and 18.65 ± 0.88%, respectively) were correlated with T3 treatment (5 mg/ml peptide). A significant different in the antimicrobial activity among each treatment after 12 days of storage was noted. At the end of refrigerated storage, the highest mean of total bacterial count, S. aureus, mold and yeast (8.36 ± 0.22, 4.19 ± 0.2, and 3.28 ± 0.05 log CFU/g, respectively) were observed in control group, while the lowest corresponded values (3.95 ± 0.2, 2.52 ± 0.25, and 1.52 ± 0.02 log CFU/g, respectively) were noted in T3 treatment. The results showed that the antimicrobial and antioxidant properties of the examined burgers were improved by incorporation of liposomes quinoa peptides encapsulated.     

A simulated annealing method for design of laminates with required stiffness properties

Designing a laminate based on its stiffness properties requires finding the optimum lamination stacking sequence to yield the required stiffness properties. The design variables to be considered are the number of layers and orientation angle of fibers in each layer group, which are treated as discrete-variables. The optimum lamination is then obtained by minimizing a cost function composed of the relative difference between the calculated effective stiffness properties and weight of trial laminate and the desired properties. This error minimization problem was solved using a modified simulated annealing heuristic method. The new simulated annealing implementation comprises a cooling procedure in which the temperature decrease relied adaptively on the objective function evolution. It is shown that the proposed method can give rise to an improvement in convergence speed. To achieve a further improvement in the performance of the method, simulated annealing parallelization implemented using the proposed cooling process. The main features of this algorithm are described and its encouraging results are presented.     

Effects of Yttrium Addition on Microstructure, Hardness and Resistance to Wear and Corrosive Wear of TiNi Alloy

TiNi alloy has a high resistance to wear and could be an excellent candidate for various tribological applications. In this paper, it was demonstrated that by addition of yttrium, hardness properties and resistance to wear and corrosive wear of TiNi alloy were improved. New yttrium rich regions were formed in microstructure of TiNi alloy. The improved properties of this alloy by the yttrium addition could be attributed to the formation of these regions. The results showed that there was an optimum content for addition of yttrium between 2% and 5% (in wt%), and above this content the improvement in properties of TiNi became minor.     

Mechanical and thermal properties of polypropylene/recycled polyethylene terephthalate/chopped rice husk composites

The various ratios of recycled polyethylene terephthalate (rPET) into polypropylene (PP) filled with 40 parts chopped rice husk per hundred part of polymer have been studied. Composites were prepared using a corotating twin screw extruder at temperature zones of 165–215, well below 250°C (rPET mp temperature) and characterized by mechanical and thermal properties. To improve the compatibility between different components, PP grafted with maleic anhydride was added as a coupling agent in all the compositions studied. The results showed that the addition of rPET improved the tensile and flexural modulus and impact strength of the composite while reducing its tensile and flexural strength. The scanning electron microscopy micrographs of samples in the injection direction showed that some particle shaped rPET inside the composites appear as drawn fibrils and some appear as plates. Differential scanning calorimetric studies showed that the addition of rPET particles to the composites decrease the PP crystallization temperatures. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Evaluating the effects of the magnitude and amplification of pseudo-static acceleration on reinforced soil slopes and walls using the limit equilibrium Horizontal Slices Method

The effects of horizontal and vertical pseudo-static forces on reinforced soil structures are investigated in the paper. In particular, the effects of the magnitude and amplification of the ground acceleration on the seismic stability of reinforced soil slopes and walls have been investigated using the Horizontal Slices Method (HSM). The HSM is a limit equilibrium method for the analysis of reinforced soil structures, which offers a number of benefits over conventional vertical slice methods. First, a parametric study using acceptable geotechnical, geometrical and design parameters was undertaken. The results of the parametric analysis are presented in dimensionless form relating to the force required to maintain stability of the slope (K) and the required length of the reinforcements (L_c/H). Different rotational and planar slip surfaces are shown for various slopes and walls with different geotechnical strength parameters. Second, the capability of the HSM to consider the effect of earthquake amplification on the stability analysis of reinforced soil structures was considered. It has been shown that the effect of horizontal seismic acceleration on the response of reinforced slopes and walls depends mainly on the geotechnical strength parameters. The effect of vertical seismic acceleration on the performance of reinforced slopes is not significant for low values of horizontal seismic acceleration. It has been concluded that ignoring the effect of the amplification phenomenon could result in an underestimated design.