Elimination of inclusions and evaporation control during melting of Ti-48Al-2Cr-2Nb-1B intermetallic alloy

Titanium aluminide intermetallic compounds have an excellent capability for use in engineering structures at high temperatures. In the present work the formation of Nb rich inclusions in microstructure and evaporation of Al during melting of γ-TiAl based alloy (Ti-48Al-2Cr-2Nb-1B (at %)) was studied. The results show that the inclusions cannot be removed even with a four-stage melting process, when elemental Nb is used as raw material. However, by replacing Nb with NbAl₃ and using a three-stage melting process, the inclusions were removed from microstructure and also evaporation of Al was reduced remarkably. Otherwise, with removing elemental Al from raw material by using TiAl compound, evaporation of Al will be very low. Increasing vessel pressure from 400 to 600 mbar will not influence evaporation of Al. The article is published in the original.     

Vehicle routing problem with uncertain demands: An advanced particle swarm algorithm

The Vehicle Routing Problem (VRP) has been thoroughly studied in the last decades. However, the main focus has been on the deterministic version where customer demands are fixed and known in advance. Uncertainty in demand has not received enough consideration. When demands are uncertain, several problems arise in the VRP. For example, there might be unmet customers’ demands, which eventually lead to profit loss. A reliable plan and set of routes, after solving the VRP, can significantly reduce the unmet demand costs, helping in obtaining customer satisfaction. This paper investigates a variant of an uncertain VRP in which the customers’ demands are supposed to be uncertain with unknown distributions. An advanced Particle Swarm Optimization (PSO) algorithm has been proposed to solve such a VRP. A novel decoding scheme has also been developed to increase the PSO efficiency. Comprehensive computational experiments, along with comparisons with other existing algorithms, have been provided to validate the proposed algorithms.     

A high step‐up half‐bridge DC/DC converter with a special coupled inductor for input current ripple cancelation and extended voltage doubler circuit for power conditioning of fuel cell systems

This paper presents a high step‐up soft switched dc–dc converter having the feature of current ripple cancelation in the input stage that is specialized for power conditioning of fuel cell systems. The converter comprises a special half‐bridge converter and a rectifier stage based upon the voltage‐doubler circuit, in which the coupled‐inductor technology is amalgamated with switched‐capacitor circuit. The input current with no ripple is the principal characteristics of this topology that is achieved by utilizing a small coupled inductor. In addition, the low clamped voltage stress across both power switches and output diodes is another advantage of the proposed converter, which allows employing the metal–oxide–semiconductor field‐effect transistors with minuscule on‐state resistance and diodes with lower forward voltage‐drop, and thereby, the semiconductors' conduction losses diminish considerably. The inherent nature of this topology handles the switching scheme based on the asymmetrical pulse width modulation in order for switches to establish the zero voltage switching, leading to lower switching losses. Besides, because of the absence of the reverse‐recovery phenomenon, all diodes turn off with zero current switching. At last, a 250‐W laboratory prototype with the input voltage 24 V and output voltage 380 V is implemented to verify the especial features of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.     

Reconfiguration and DG Sizing and Placement Using Improved Shuffled Frog Leaping Algorithm

Abstract

In this paper is proposed a reconfiguration methodology with the presence of Distributed Generation (DG), aimed at achieving the minimum power loss, minimum number of switching operation and minimum deviation of bus voltage while satisfying all constraints using improved shuffled frog leaping algorithm (ISFLA).The performance of the proposed method is examined on 33 and 69 bus IEEE test distribution systems. The ISFLA performance is evaluated with the well-known algorithm including of harmony search algorithm (HSA), refined genetic algorithm (GRA), particle swarm optimization (PSO), differential evolutionary (DE) and conventional SFLA. Simulation results showed that the total power loss and voltage bus minimum in primary distribution network can be reduced significantly. Also the results in different scenarios are showed that the simultaneous reconfiguration and DG placement method is better in less losses and also in more minimum voltage. Moreover, the ISFLA superiority is proved in comparison with the HAS, GRA, PSO, DE, and SFLA in view of more convergence speed and accuracy and also converges in less number iteration. Also, the performance of the proposed method is favorable compared to previous studies.     

Magnetic and photocatalytic properties of CoFe2O4/Ni nanocomposites

Journal of Electroceramics - In this research, hard/soft CoFe2O4/Ni magnetic nanocomposite samples with different concentrations of Ni were successfully produced by a two-step mechanical alloying...     

Protein Kinases and Parkinson’s Disease

Currently, the lack of new drug candidates for the treatment of major neurological disorders such as Parkinson’s disease has intensified the search for drugs that can be repurposed or repositioned for such treatment. Typically, the search focuses on drugs that have been approved and are used clinically for other indications. Kinase inhibitors represent a family of popular molecules for the treatment and prevention of various cancers, and have emerged as strong candidates for such repurposing because numerous serine/threonine and tyrosine kinases have been implicated in the pathobiology of Parkinson’s disease. This review focuses on various kinase-dependent pathways associated with the expression of Parkinson’s disease pathology, and evaluates how inhibitors of these pathways might play a major role as effective therapeutic molecules.     

Inhibition of mild steel corrosion in hydrochloric acid medium by polymeric inhibitors containing residues of essential amino acid methionine

Ethyl ester hydrochloride of amino acid l-methionine 1 was converted to cationic monomers N,N-diallyl methionine ethyl ester hydrochloride 2 and hydrochloride salt of N,N-diallylmethionine 3. Cationic monomers 2 and 3 underwent alternate copolymerization with SO₂ in dimethyl sulfoxide to give terpolymers 4 and 5, respectively, both having?≈?1:1 ratio of sulfide and sulfoxide motifs owing to O transfer from dimethyl sulfoxide to the S. The sulfide groups in 5 have been oxidized with H₂O₂ to give polymer sulfoxide 6. In the presence of a small concentration of 35.2 µM (~?11?±?1 ppm) of each of the polymers 4, 5 and 6, the inhibition efficiency against mild steel corrosion in 1.0 M HCl at 60 °C was determined to be 90.8, 98.7 and 93.0%, respectively. The inhibition efficiency obtained from gravimetric weight loss was corroborated by the findings of potentiodynamic polarization and electrochemical impedance spectroscopy methods. Adsorption of polymer compounds onto the mild steel surface followed a mixture of chemisorption and physisorption processes and obeyed Langmuir, Temkin and Freundlich adsorption isotherms. The X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques further confirmed that the synthesized compounds formed a protective film onto the metal surface and prove it against further corrosion attack.     

N ‐acetylcysteine–PLGA nano‐conjugate: effects on cellular toxicity and uptake of gadopentate dimeglumine

Gadolinium as a contrast agent in MRI technique combined with DTPA causes contrast induced nephropathy (CIN) and nephrogenic systemic fibrosis (NSF) which can reduce by usage of antioxidants such as N‐acetyl cysteine by increasing the membrane''s permeability leads to lower cytotoxicity. In this study, N ‐acetyl cysteine‐PLGA Nano‐conjugate was synthesized according to stoichiometric rules of molar ratios andafter assessment by FTIR, NMR spectroscopy and Atomic Force Microscopy (AFM) imaging was combined with Magnevist® (gadopentetate dimeglumine) and its effects on the renal cells were evaluated. MTT [3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐Diphenyltetrazolium Bromide] and cellular uptake assays have indicated relatively significant toxicity of magnevist (P  < 0.05) on three cell lines including HEK293, MCF7 and L929 compared to other synthesized ligands that shown no toxicity. Moreover, systemic evaluation has shown no notable changes of blood urea nitrogen (BUN) and creatinine in kidney of mice. In consequence, antioxidant effect was increased as well as the renal toxicity of the contrast agent reduced at the cell level. As a result, PLGA‐NAC nano‐conjugate can be a promising choice for decreasing the magnevist toxicity for treatment and prevention of CIN and will be able to open a new horizon to research on reduction of toxicity of contrast agents by using nanoparticles.Inspec keywords: blood, toxicology, nanofabrication, cellular biophysics, biomedical materials, nanoparticles, chromatography, cancer, biodegradable materials, biomedical MRI, kidney, pH, nanomedicine, patient treatment, diseases, atomic force microscopy, Fourier transform infrared spectraOther keywords: cellular toxicity, gadopentate dimeglumine, contrast agent, magnetic resonance imaging technique, diethylenetriamine pentaacetate, contrast‐induced nephropathy, nephrogenic systemic fibrosis, stoichiometric rules, molar ratios, dimethyl sulphoxide solution, chromatography techniques, nuclear magnetic resonance spectroscopy, atomic force microscopy imaging, Magnevist®, gadopentetate dimeglumine, renal cells, MTT cytotoxicity, human embryonic kidney‐293, L929 cell lines, in vitro conditions, cellular uptake assays, Magnevist uptake, antioxidant effect, renal toxicity, cell level, PLGA nanocarrier, acetylcysteine nanoconjugate, Magnevist toxicity, N‐acetylcysteine–PLGA nano‐conjugate, N‐acetyl cysteine‐poly‐lactic‐co‐glycolic acid nanoconjugate     

Multiple-antenna capacity in correlated Rayleigh fading with channel covariance information

We analyze a mobile multiple input multiple output wireless link with M transmit and N receive antennas operating in a spatially correlated Rayleigh flat fading environment. Only the correlations between the channel coefficients are assumed to be known at the transmitter and the receiver. The channel coefficients are correlated in space and uncorrelated in time from one coherence interval to another. These coefficients remain constant for a coherence interval of T symbol periods after which they change to another independent realization according to the spatial correlation model. For this system we characterize the structure of the input signal that achieves capacity. The capacity achieving transmit signal is expressed as the product of an isotropically distributed unitary matrix, an independent nonnegative diagonal matrix and a unitary matrix whose columns are the eigenvectors of the transmit fade covariance matrix. For the case where the number of transmit antennas M is larger than the channel coherence interval T, we show that the channel capacity is independent of the smallest M-T eigenvalues of the transmit fade covariance matrix. In contrast to the previously reported results for the spatially white fading model where adding more transmit antennas beyond the coherence interval length (M>T) does not increase capacity, we find that additional transmit antennas always increase capacity as long as their channel fading coefficients are spatially correlated with the other antennas. We show that for fast hopping or fast fading systems (T=1) with only channel covariance information available to the transmitter and receiver, transmit fade correlations are beneficial. Mathematically, we prove this by showing that capacity is a Schur-convex function of the vector of eigenvalues of the transmit fade correlation matrix. We also show that the maximum possible capacity gain due to transmitter fade correlations is 10logM dB.