Improved equation of state for ionic liquids using surface tension

The major objective of this work was the development of a reliable model to describe volumetric properties of ionic liquids (ILs). In this regard, we have applied the Ihm–Song–Mason equation of state (EOS) to some phosphonium- and imidazolium-based ILs. Three temperature-dependent parameters in the equation of state have been scaled based on the surface tension and the liquid density at room temperature. In order to improve the predictive power of the mentioned EOS for ILs, we have proposed using a simple modification. We have taken 1,228 experimental points to show the reliability of the improved EOS. The comparison of predicted densities with literature data over a broad range of temperature, 293–472 K, and pressures up to 200 MPa led to encouraging results. The average absolute deviation of calculated densities from literature values was found to be 0.75%.     

Analysis of ultrafast nonlinear phenomena��s influences on output optical pulses and four-wave mixing characteristics in semiconductor optical amplifiers

We have analysed the output pulse characteristics of semiconductor optical amplifier (SOA). It is shown that they can be modified due to the variation of input parameters, such as, gain, input pulsewidth, input pulse energy and effects imposed by the medium. Therefore, the influence of these parameters are analysed on the output pulse shape, spectrum, chirp and pulsewidth. We have used the nonlinear propagation equation taking into account the gain spectrum dynamics, gain saturation which depends on carrier depletion, carrier heating, spectral hole-burning, group velocity dispersion, self-phase modulation and two photon absorption. We have used the finite-difference beam propagation method to simulate the wave evolution both in time and spectral domain in the SOA. We have also simulated the four-wave mixing characteristics between pulses for various input pulses. An accurate output pulse shape can be achieved by controlling the mentioned parameters. To the authors knowledge, pulse shaping in co-propagation regime due to medium effect and input pulse shapes in presence of all nonlinear effects relevant to picosecond regime have been studied comprehensively, for the first time in this work.     

Damage detection and denoising in two-dimensional structures using curvelet transform by wrapping method

The main objectives of this study are to present a vibration-based damage identification method and also a denoising mode shape approach applicable to two-dimensional structures using curvelet transform. For this purpose, the curvelet transform via wrapping method is employed. The reliability of the proposed technique is demonstrated through a verification study by comparing the results of numerical and those of the experimental data in plate structures. Two case studies, one-story and three-story shear walls assuming damages at arbitrary locations, are examined in which different noise levels are included. Good agreement between the simulated and assumed damage in both example is demonstrated. The results confirm the robustness and high performance of the proposed method in detecting the damage in plate structure and eliminating the noises.     

Performance assessment of new perturbed hard-sphere equation of state for molten metals and ionic liquids: Application to pure and binary mixtures

This work addresses modeling the pressure–volume–temperature (PVT) properties of molten metals and ionic liquids (ILs) using a new perturbed hard-sphere equation of state (PHS EOS). Two temperature-dependent parameters appeared in the EOS, are correlated with two scaling constants σ and ε. Knowing these parameters, the proposed EOS is applied to these classes of liquids. The reliability of the proposed model is checked by comparing with 3177 experimental density data points. The average absolute deviations (AAD) of predicted densities of molten metals and ILs from literature data are found to be 1.35% and 0.56%, respectively. The extension of PHS EOS to binary metal alloys and IL + IL is also discussed. Generally, 609 data points for binary mixtures have been examined. The AAD of the predicted results are found to be 1.03%.     

A Novel Approach for the Synthesis of Furopyrimidine and Oxobenzofuran Derivatives

A novel, efficient one‐pot approach for the synthesis of furopyrimidine and oxobenzofuran derivatives 4 by a multicomponent reaction of an isocyanide, an aldehyde, and a CH‐acid compound in CH₂Cl₂ is reported (Scheme 1 and Table). The reactions were completed after 20 h at room temperature. This method has the advantages of high yields, simple methodology, and easy workup.     

Reversed‐phase vortex‐assisted liquid–liquid microextraction: A new sample preparation method for the determination of amygdalin in oil and kernel samples

A novel, simple, and rapid reversed‐phase vortex‐assisted liquid–liquid microextraction coupled with high‐performance liquid chromatography has been introduced for the extraction, clean‐up, and preconcentration of amygdalin in oil and kernel samples. In this technique, deionized water was used as the extracting solvent. Unlike the reversed‐phase dispersive liquid–liquid microextraction, dispersive solvent was eliminated in the proposed method. Various parameters that affected the extraction efficiency, such as extracting solvent volume and its pH, vortex, and centrifuging times were evaluated and optimized. The calibration curve shows good linearity (r² = 0.9955) and precision (RSD < 5.2%) in the range of 0.07–20 μg/mL. The limit of detection and limit of quantitation were 0.02 and 0.07 μg/mL, respectively. The recoveries were in the range of 96.0–102.0% with relative standard deviation values ranging from 4.0 to 5.1%. Unlike the conventional extraction methods for plant extracts, no evaporative and re‐solubilizing operations were needed in the proposed technique.     

(2‐Aminopyrimidine‐κN1)aqua(pyridine‐2,6‐dicarboxylato‐κ3O2,N,O6)copper(II): X‐ray and DFT calculated structure

In the title compound, [Cu(C₇H₃N₂O₄)(C₄H₅N₂)(H₂O)], (I), pyridine‐2,6‐dicarboxylate (pydc²⁻), 2‐aminopyrimidine and aqua ligands coordinate the Cu^II centre through two N atoms, two carboxylate O atoms and one water O atom, respectively, to give a nominally distorted square‐pyramidal coordination geometry, a common arrangement for copper complexes containing the pydc²⁻ ligand. Because of the presence of Cu...X_bridged contacts (X = N or O) between adjacent molecules in the crystal structures of (I) and three analogous previously reported compounds, and the corresponding uncertainty about the effective coordination number of the Cu^II centre, density functional theory (DFT) calculations were used to elucidate the degree of covalency in these contacts. The calculated Wiberg and Mayer bond‐order indices reveal that the Cu...O contact can be considered as a coordination bond, whereas the amine group forming a Cu...N contact is not an effective participant in the coordination environment.     

Corrosion and biological behavior of nanostructured 316L stainless steel processed by severe plastic deformation

Nanostructured metals have different mechanical, chemical, and physical behaviors in comparison with the microstructured ones. Numerous research studies demonstrated that the biological behavior of nanostructured metallic implants was improved significantly. Concerning the nanostructured metals, decreasing the corrosion rate and the releasing of hazardous ions from metallic implants, and thus increasing the biocompatibility of implants are due to improving the native oxide layer. In the present study, nanostructured 316L stainless steel (biomedical grade) was manufactured via equal channel angular pressing (ECAP) method. To do so, the 316L stainless steel (SS) was exposed to the ECAP operation for eight passes. The impact of the ECAP process on corrosion behavior of SS samples was evaluated through performing the electrochemical polarization corrosion tests in Ringer's solution. Scanning electron microscopy was employed to study the surface morphology of common SS and ECAPed SS sample after the electrochemical polarization tests. Moreover, the biological behavior of the samples was evaluated via cell culture using fibroblast cells. The corrosion test results revealed a substantial decrease of corrosion rate from 3.12 (coarse‐grained sample) to 0.42 μA cm^?2 (for nanostructured). Furthermore, the cell proliferation in the interface of nanostructured sample and cell culture medium enhanced dramatically compared with the coarse‐grained one. The much better biological behavior of nanostructured SS sample in comparison with the coarse‐grained one is mostly due to the significant decrease of corrosion rate on the surface of SS samples, and the presence of much more chrome oxide on the surface of SS sample. Copyright © 2015 John Wiley & Sons, Ltd.     

Improved hydrogen evolution on glassy carbon electrode modified with novel Pt/cetyltrimethylammonium bromide nanoscale aggregates

A novel, cost‐effective, and simple electrocatalyst based on a Pt‐modified glassy carbon electrode (GCE), using cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, is reported. Am‐phiphilic...