Determination of carbamazepine in formulation samples using dispersive liquid–liquid microextraction method followed by ion mobility spectrometry

A simple, sensitive, fast and efficient method based on dispersive liquid–liquid microextraction (DLLME) followed by ion mobility spectrometry (IMS) has been proposed for preconcentration and trace detection of carbamazepine (CBZ) in formulation samples. In this method, 1 mL of methanol (disperser solvent) containing 80 μL of chloroform (extraction solvent) was rapidly injected by a syringe into a sample. After 5 min centrifugation, the preconcentrated carbamazepine in the organic phase was determined by IMS. Development of DLLME procedure includes optimization of parameters influencing the extraction efficiencies such as kind and volume of extraction solvent, disperser solvent and salt addition, centrifugation time and pH of the sample solution. The proposed method presented good linearity in the range of 0.05–10 μg mL^?1 and the detection limit was 0.025 μg mL^?1. The repeatability of the method expressed as relative standard deviation was 6 % (n = 5). This method has been applied to the analysis of carbamazepine formulation samples with satisfactory relative recoveries ≤75 %.     

The reaction of N-isocyaniminotriphenylphosphorane (NICITPP) with some of cyclic ketones and a primary amine in the presence of 3-phenyl-2-propynoic acid

The 1:1 imine intermediate generated by the addition of a primary amine to a cyclic ketone is trapped by N-isocyaniminotriphenylphosphorane in the presence of 3-phenyl-2-propynoic acid and the corresponding iminophosphorane intermediate was formed. Disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were completed in neutral conditions at room temperature (18–26°C). The disubstituted 1,3,4-oxadiazole derivatives were produced in excellent yields.     

High‐Throughput Measurement of Binding Kinetics by mRNA Display and Next‐Generation Sequencing

There is great demand for high‐throughput methods to characterize ligand affinity. By combining mRNA display with next‐generation sequencing, we determined the kinetic on‐ and off‐rates for over twenty thousand ligands without the need for synthesis or purification of individual members. Our results are reproducible and as accurate as those obtained with other methods of affinity measurement.     

A Change of Phase Morphology in Poly Lactic Acid/Poly Methyl Methacrylate Blends Induced by Graphene Nano Sheets

Blending of polymeric materials is an effective way to obtain materials with specific properties, since the properties of these multiphase polymeric materials are not only affected by the properties of the component polymers but also by the morphology formed. The research described here was focused on investigation of the morphology of polymer blends of poly lactic acid (PLA) and poly methyl methacrylate (PMMA) and the PLA/PMMA blends containing various amounts of graphene nano plates, (GNP). In this work, the blends were prepared by solution casting and the morphologies of these nano filled polymer blends were studied. By adding graphene nano plates into the PLA/PMMA blends, the morphology changed for all compositions. It was very interesting to note that the GNP were found to be preferentially located in one of the polymer phases, different for the different loadings, and its location determined the final morphology of the PLA/PMMA blends. The morphology of the blends was observed by SEM and the composition-morphology dependence responses were investigated using a Fourier transform infra-red (FTIR) spectroscopy technique.     

A Newton–Krylov finite volume algorithm for the power-law non-Newtonian fluid flow using pseudo-compressibility technique

An implicit Newton–Krylov finite volume algorithm has been developed for efficient steady-state computation of the power-law non-Newtonian fluid flows. The pseudo-compressibility technique is used for the coupling of continuity and momentum equations. The spatial discretization is central (second-order) for both convective and diffusive terms and the accuracy of the solution is verified. The nine block diagonal Jacobian matrix (needed for implicit formulation) is computed directly through the flux differentiation. Five-diagonal and three-diagonal block matrices (the simplified versions of the main Jacobian matrix) are used with the ILU(0 & 1) and the Thomas linear solvers for preconditioning, respectively. The performance of the Newton-GMRES solver is examined in detail for different preconditioning strategies. The effects of the power-law behavior index and Re number on the convergence rate are also studied. The performance of the Newton-BiCGSTAB and the Newton-GMRES solvers are compared with each other. The results show, the ILU(1)/Newton-GMRES is the most efficient combination that is robust even in high Reynolds number shear-thinning fluid flow cases.     

N-Isocyaniminotriphenylphosphorane (Ph3PNNC) as an Efficient Reagent for the Synthesis of Fully Substituted 1,3,4-Oxadiazoles from 3-Phenyl-2-Propynoic Acid,Secondary Amines and Aromatic Bis-Aldehydes

Abstract

Reactions of N-isocyaniminotriphenylphosphorane (Ph₃PNNC) with aromatic bis-aldehydes (isophthalaldehyde and terphthalaldehyde) in the presence of 3-phenyl-2-propynoic acid and secondary amines proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions and no side reactions were observed.     

An Efficient Solvent-free Synthetic Technique of 4,4’-Diaminotriarylmethane Leuco Materials

An efficient, versatile and solvent-free synthetic technique of diaminotriarylmethanes was reached by treating N,N-dimethylaniline with some arylaldehydes over zirconium(IV) oxide chloride (ZrOCl2•8H2O), in which ZrOCl2•8H2O has good activity, easy availability, recovery as well as reusability.     

A fuzzy algorithm for continuous capacitated location allocation model with risk consideration

This paper presents a continuous capacitated location-allocation model with fixed cost as a risk management model. In the presented model, the fixed cost consists of production and installation costs. The model considers risk as percent of unsatisfied demands. The fixed cost is assigned to a zone with a predetermined radius from its center. Because of uncertain environment, demand in each zone is investigated as a fuzzy number. The model is solved by a fuzzy algorithm based on α-cut method. After solving the model based on different α-values, the zones with the largest possibilities are determined for locating new facilities and the best locations are calculated based on the obtained possibilities. Then, the model is solved based on different α-values to determine best allocation values. Also, this paper proposes a Cross Entropy (CE) algorithm considering multivariate normal and multinomial density functions for solving large scale instances and is compared with GAMS. Finally, a numerical example is expressed to illustrate the proposed model.