A stereoselective three‐component reaction: One‐pot synthesis of cis‐isoquinolonic acids catalyzed by silica sulfuric acid under mild and heterogeneous conditions

A mild and stereoselective three‐component one‐step synthesis of cis‐isoquinolonic acid using silica sulfuric acid as a heterogeneous catalyst from an aldehyde, amine and homophthalic anhydride in acetonitrile is described. This new method produces pure products in high yields (81‐91%).     

A Sensitive Method for the Determination of Methadone in Biological Samples Using Nano-Structured α-Carboxy Polypyrrol as a Sorbent of SPME

Nano-structured α-carboxy polypyrrol (PPy- α-COOH) was used as a coating of solid-phase microextraction (SPME) fiber to increase the extraction efficiency of headspace solid phase microextraction (HS-SPME) of methadone (MDN) in biological samples. The carboxy-endcapped polypyrrole film was prepared via electrochemical deposition on a platinum wire. A nano-fibrous structure of PPy-α-COOH with a diameter of 120 nm was obtained. The porous surface structure of the film, revealed by scanning electron microscopy, provided high surface areas and allowed for high extraction efficiency of methadone. Then the analysis of the extracts was carried out by a gas chromatography-flame ionization detector. In order to achieve maximum extraction efficiency, different parameters affecting the extraction conditions were optimized. Under the optimized conditions, the limit of detections and the limit of quantifications of the method in the range of 0.02–0.035 and 0.06–0.10 μg L⁻¹ were obtained for different matrices. The relative recoveries in different samples were in the range of 95–97%. Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of MDN in human urine and plasma samples in the range of microgram per liter, and suitable results were obtained (RSDs <5.3%).

     

Tetrakis(acetonitrile)copper(I) hexafluorophosphate catalyzed coumarin synthesis via pechmann condensation under solvent‐free condition

Tetrakis(acetonitrile)copper(I) hexafluorophosphate ( Cu(CH₃CN)₄PF₆) is used as an efficient catalyst in the Pechmann condensation reaction of phenols with ethyl acetoacetate leading to the formation of coumarin derivatives in excellent yields under solvent free conditions at ambient temperature. The method is simple, solvent‐free and gives excellent yields in a short reaction time. J. Heterocyclic Chem.,(2011).     

A palladium-catalyzed one-pot procedure for the regioselective dimerization and cyanation of indoles

A one-pot method for the regioselective dimerization and cyanation of indoles has been developed. The reaction uses safe and nontoxic K₄[Fe(CN)₆]·3H₂O as the cyanating agent which introduces selectively a cyano group into the 3-position of biindoles with high efficiency.     

Modeling semiconductor devices by using Neuro Space Mapping

In this paper a new method for modeling semiconductor devices by use of the drift-diffusion (DD) model and neural networks is presented. Unlike the hydrodynamic (HD) model which is complicated, time consuming with high processing cost, the proposed method has lower complexity and lower simulation time. In this method the RBF neural network has been used for correcting parameters in the drift-diffusion model. Therefore solving approximate model (DD) causes to obtain accurate response. The proposed method is first applied to a silicon n-i-n diode in one dimension, and then to a silicon thin-film MOSFET in two-dimensions, both for interpolation and extrapolation. The obtained results for basic variables, i.e., electron and potential distribution for different voltages, confirm the high efficiency of the proposed method.     

Solution of the Falkner–Skan equation for wedge by Adomian Decomposition Method

The Adomian Decomposition Method is employed in the solution of the two dimensional laminar boundary layer of Falkner–Skan equation for wedge. This work aims at the solution of momentum equation in the case of accelerated flow and decelerated flow with separation. The Adomian Decomposition Method is provided an analytical solution in the form of an infinite power series. The effect of Adomian polynomials terms is considered on accuracy of the results. The velocity profiles in boundary layer are obtained. Results show a good accuracy compared to the exact solution.     

Quark masses and flavor-mixing angles in a six-quark model of quantum flavordynamics

The Cabibbo-like flavor-mixing angles are related to quark masses through spontaneous symmetry breaking in an illustrative model of quantum flavordynamics based on the SU_2L x SU_2R x U₁ flavor gauge group and on six quark flavors. Theoretical and experimental consequences of the scheme are discussed.     

Hierarchy of masses for pseudoscalar and vector mesons

Assuming that quark flavors beyond isospin, strangeness, and charm exist, we use the relationship between the structure of chiral symmetry breaking of the strong interaction and the Cabibbo angle in order to estimate the masses of the pseudoscalar and vector mesons carrying the fifth (beauty), sixth (truth), and seventh (illusion) quark flavors.