On rough set and fuzzy sublattice

Let L be a lattice with the least element 0 and the greatest element 1 and let θ be a full congruence relation on L. In this paper, the notion of θ-upper and θ-lower approximations of a fuzzy subset of L is introduced and some important properties will be studied.     

Dielectrophoretic trapping of selenium nanorods for use in device applications

Dielectrophoretic alignment of the Selenium (Se) nanorods is reported for electrical characterization and possible applications as micro/nano devices. Selenium nanorods were successfully synthesized using a reverse microemulsion process. The produced material was investigated structurally using X-ray diffraction and transmission electron microscope. Suspensions of the Se powder in the concentration of 0.1 (g/l) were prepared in pure ethanol. Interdigitated platinum electrodes were employed for manipulation of suspended materials in the fluid. When Se particles were exposed to the platinum electrodes in two frequencies of 10 and 100 kHz, dielectrophoretic force captured suspended particles onto the interdigitated micro-electrode array. The trapped Se nanorods were aligned along the electric field lines and bridged the electrode gaps. Dielectrophoretic entrapment of Se nanorods on microelectrode was also detected by impedance measurements. The device was characterized and can potentially be used as a nanodevice.     

Olive oil oxidation: Rejection points in terms of polar, conjugated diene, and carbonyl values

The changes in polar (POV), conjugated diene (CDV), and carbonyl (CV) values of a set of olive oil samples with a wide range of compositional parameters were monitored during 16 h heating at 180 °C. The POV, CDV, and CV linearly changed till the end of the heating process and increased on average from 6.8%, 7.0 mmol/l, and 11.7 μmol/g to 30.1%, 29.3 mmol/l, and 58.1 μmol/g, respectively. The CDV and CV of the olive oil samples were significantly correlated with the POV (R² > 0.98). The limits of 24% and 27% POV corresponded to 24.5 and 27.4 mmol/l CDV and 45.1 and 51.0 μmol/g CV, respectively.     

Decomposition and decoloration of synthetic dyes using hot/liquid (subcritical) water

We have studied the decomposition and decoloration of 4-(2-Hydroxynaphthylazo) benzenesulfonic acid sodium salt (AO7, acid dye) as a model for textile wastes by using a flow-type subcritical water system. The operating temperature was ranged from 180 to 374 °C at 10-25 MPa at a wide range of residence time. The pressure (up to 25 MPa) did not affect the decomposition reactions. AO7 completely decomposed at higher temperatures and or longer residence times. The main products from decomposition of AO7 were found to be 2-naphthalenol, phenol, 1,1′-Binaphthalene-2,2′-diol, and N-(phenylmethylene)benzenamine. In order to identify the decomposition pathways, the products were also individually treated under a batch type subcritical water conditions. We found that 2-naphthalenol underwent to further decomposition to 1,1′-Binaphthalene-2,2′-diol during the subcritical water reaction. Other decomposition products resulted from the decomposition of directly AO7. Kinetic model of the subcritical water reaction was developed by considering major products. The kinetic constants obtained from the proposed reaction pathway showed good agreement with experimental results.     

A comparison of artificial neural networks learning algorithms in predicting tendency for suicide

New approaches adopted by behavioral science researchers to use modern modeling and predicting tools such as artificial neural networks have necessitated the study and comparison of the efficiency of different learning algorithms of these networks for various applications. By using well-known and different learning algorithms, this study examines and compares the Perceptron artificial neural network as predicting tendency for suicide based on risk factors within 33 input parameters framework used in neural network. To find the “best” learning algorithm, the algorithms were compared in terms of train and capability. The experimental data were collected through questionnaires distributed among 800 university students. All questionnaires used in this research were standardized with appropriate validity and reliability. The study findings indicated that LM and BFG algorithms had close evaluation in terms of performance index and true acceptance rate (TAR), and they showed higher predictive accuracy than the other algorithms. Furthermore, CFG algorithm had the minimum training time.     

Efficient three-component Gewald reactions under Et3N/H2O conditions

In a medium consisting of triethylamine and water, α-methylene ketones undergo room temperature Gewald reactions with elemental sulfur and ethyl cyanoacetate (or malononitrile) to yield 2-aminothiophene derivatives efficiently within short time periods. Because of the high polarity of the medium, products precipitate in the reaction mixtures spontaneously. This makes isolation of the products easy by simple filtration and avoids cumbersome chromatographic separations. Mechanistic studies suggest that the reactions proceed via a Knoevenagel condensation pathway.     

An efficient solid phase extraction of Pb2+ using tannic acid-coated cerium oxide nanoparticles followed by electrothermal atomic absorption spectrometry

Cerium oxide-Tannic acid (CeO₂-TA) nanocomposite were used for preconcentration of Pb²⁺ followed by electrothermal atomic absorption spectrometry. Cerium oxide nanoparticles were synthesized by microwave method and modified by tannic acid to produce CeO₂-TA nanocomposite. In order to optimize the experimental conditions, Response surface methodology based on central composite design was used. The obtained results show that the calibration curve was linear in the range of 0.025–1.5 µg L^?1 Pb²⁺. Also, the accuracy of the method was validated by the analysis of certified referenced material. Finally, the proposed method was applied for determination of Pb²⁺ in different real samples.     

Fischer–Tropsch synthesis over an iron–cobalt–manganese (ternary) nanocatalyst prepared by hydrothermal procedure: Effects of nanocatalyst composition and operational conditions

The Fischer–Tropsch (F–T) reaction has been studied over a series of unsupported Fe–Co–Mn nanocatalysts synthesized by the hydrothermal procedure to investigate the effects of Mn addition and Fe/Co mole ratios on the catalytic activity and selectivity in a fixed-bed reactor. The main intention is to maximize the light olefins $\left({\text{C}}_2^{=}?{\text{C}}_4^{=}\right)$ selectivity by controlling the nanocatalyst composition and process conditions. It was found that the 68% Fe–16% CO–16% Mn nanocatalyst was an optimum nanocatalyst for ${\text{C}}_2^{=}?{\text{C}}_4^{=}$ olefins production from synthesis gas. The effects of a range of operational conditions on the performance of optimum nanocatalyst were investigated. The results are shown that the maximum olefin/(methane + paraffin) ratio has been obtained over 68% Fe–16% Co–16% Mn sample at an operational temperature of 290 °C, the H₂/CO molar ratio of 1/1, the space velocity of 3000 h^?1 and 2 bar pressure. Characterization of nanocatalysts was carried out using XRD, N₂ physisorption, TEM, TGA, DSC, TPR, FE-SEM and EDS.     

Pd doped WO3 films prepared by sol–gel process for hydrogen sensing

The sol gel method was employed to prepare peroxopolytungstic acid (P-PTA). Palladium chloride salt was dissolved in the sol with different Pd:W molar ratios and coated on Al₂O₃ substrates by spin coating method. XRD and XPS techniques were used to analyze the crystal structure and chemical composition of the films before and after heat treatment at 500 °C. We observed that Pd can modify the growth kinetic of tungsten trioxide nanoparticles by reducing the crystallite size and as a result can improve hydrogen sensitivity. Resistance-sensing measurements indicated sensitivity of about 2.5 × 10⁴ at room temperature in hydrogen concentration of 0.1% in air. Considering all sensing parameters, an optimum working temperature of 100 °C was obtained.     

Electrochemical oxidation of dopamine in the presence of sulfhydryl compounds: Application to the square-wave voltammetric detection of penicillamine and cysteine

Electro-oxidation of dopamine at a glassy carbon electrode was investigated in the presence of some biologically important thiols (R-SH), e.g. cysteine and penicillamine. Results of cyclic voltammetric studies together with the spectrophotometric foundations via Ellman's test during the controlled-potential coulometry show a nucleophilic addition/reduction of thiol to the electrochemically generated dopaminoquinone by a 1 + 4 Michael addition. The resulting ring substituted substrate (as RS-form) is more easily oxidized leading to an increase in the anodic current of dopamine, which is proportional to the concentration of thiol. The square-wave voltammetry (SWV) were applied as a very sensitive voltammetric detection method for the detection of cysteine and penicillamine. A linear response from 0.10 to 2.5 μM with a detection limit of 0.08 μM is resulted by the voltammetric determinations for penicillamine. The effect of other biological thiols, such as N-acetyl cysteine, glutathione, methionine, captopril and mercaptoglycine were also assessed and found to present no appreciable change in the voltammetric response of dopamine. The proposed method can be considered as a relatively selective method for the voltammetric detection of penicillamine and cysteine. The practical utility of the method was investigated in the determination of thiol species in pharmaceutical preparations.