Electronic and optical properties of Full-Heusler alloy Fe3?xMnxSi

The electronic and optical properties of the nonstoicheiometric Heusler alloys Fe_3−x Mn _x Si with (x = 0,0.75,1,1.25,2) have been studied by the first principles study in the framework of the density functional theory (DFT). Optical properties including the dielectric function, refractive index, energy-loss spectra, absorption spectra, optical conductivity and reflectivity were also calculated. Results show that the electronic structure of Fe_3−x Mn _x Si alloys have half-metallic property for (x = 0.75,1,1.25). The real part of dielectric function has two main peaks in high energies. From absorption spectra it can be seen that absorption curves in low energy are broadened with respect to higher energies. The refractive index has a nonlinear dispersion in the energy range of 45–55 eV. The energy of plasmon peaks obtained from electron energy loss function (ELF) are about 25 eV.     

Optimization of reaction parameters for the sonophotocatalytic degradation of hydroquinone

Research on Chemical Intermediates - In the present work, the degradation of hydroquinone in synthetic wastewater under sonocatalytic, photocatalytic, and sonophotocatalytic conditions was...     

Applications of Inorganic Polymeric Materials II: Polysilanes

Polysilanes which cover one of the most attractive and challenging fields, are high molecular weight polymers with inorganic elements in their backbone. These materials have silicon atoms in their main chain and exhibit unique properties resulting from the easy delocalization of sigma electrons in the Si─Si bonds. There are many technical uses as well as applications of these materials such as precursors of silicon carbide ceramics; a strengthening agent in porous ceramic; imaging materials in microlithography; photoiniting in radical reactions; and photoconducting, conducting, and semiconducting which are due to the unusual mobility of sigma electrons. In this work, the main structural features, properties, and some other important and recent applications of polysilanes are discussed.     

Effect of ceria and zirconia nanoparticles on mechanical behavior of nanocomposite hybrid coatings

Epoxy-silica based hybrid nanocomposite coatings have been developed with different organicinorganic contents by sol–gel process. Various ratios of ceria and zirconia colloidal dispersions as inorganic nanoparticles are uniformly distributed in the hybrid sol. The hybrid sols are prepared by hydrolysis and condensation of 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetraethylorthosilicate (TEOS) in acidic solution using bisphenol A (BPA) and 1-methyl-imidazol (MI). A thin layer of each sol is coated on a micro-glass slide and 1050 aluminum alloy as substrates. The effect of alkoxysilane precursors (i.e. TEOS and GPTMS) and inorganic to organic molar ratio are investigated. Nanoindentation and dynamic mechanical analysis (DMA) performed to characterize the mechanical properties of the coatings in nanorange scale. It is revealed that all hybrid nanocomposite coatings had appropriate flexibility and strong interfacial interaction with the aluminum alloy substrate. It is proposed that the ceria and zirconia nanoparticles can be bonded to the surrounding of siloxane ring which can be induced high restriction in polymeric chain mobility in dynamic mechanical analysis. Nanoindentation tests showed that by increasing the inorganic phase in the nanocomposite, both elastic modulus and hardness increase, especially they are very intense in the higher levels of inorganic content.     

Application of aeration‐assisted homogeneous liquid–liquid microextraction procedure using Box–Behnken design for determination of curcumin by HPLC

A simple, efficient, and rapid sample preparation method based on aeration‐assisted homogeneous liquid–liquid microextraction was developed for determination of curcumin in food samples by high‐performance liquid chromatography. The centrifuge step has been eliminated in this procedure. The effects of some variables, such as pH, volume of extraction solvent, extraction time, and salt effect, were studied through a Box–Behnken design method. Under the optimum conditions, calibration curves of curcumin were linear in the range of 0.08‐4000 μg/mL with R² = 0.997. Limit of detection and relative standard deviation were 0.019 μg/mL and 3.01%, respectively. The preconcentration factor achieved was 166. The proposed method was successfully applied to determination of curcumin in various food samples.     

An exact feature selection algorithm based on rough set theory

Feature reduction based on rough set theory is an effective feature selection method in pattern recognition applications. Finding a minimal subset of the original features is inherent in rough set approach to feature selection. As feature reduction is a Nondeterministic Polynomial‐time‐hard problem, it is necessary to develop fast optimal or near‐optimal feature selection algorithms. This article aims to propose an exact feature selection algorithm in rough set that is efficient in terms of computation time. The proposed algorithm begins the examination of a solution tree by a breadth‐first strategy. The pruned nodes are held in a version of the trie data structure. Based on the monotonic property of dependency degree, all subsets of the pruned nodes cannot be optimal solutions. Thus, by detecting these subsets in trie, it is not necessary to calculate their dependency degree. The search on the tree continues until the optimal solution is found. This algorithm is improved by selecting an initial search level determined by the hill‐climbing method instead of searching the tree from the level below the root. The length of the minimal reduct and the size of data set can influence which starting search level is more efficient. The experimental results using some of the standard UCI data sets, demonstrate that the proposed algorithm is effective and efficient for data sets with more than 30 features. © 2014 Wiley Periodicals, Inc. Complexity 20: 50–62, 2015