Statistics and characterization of matrices by determinant and trace

The Ramanujan Journal - Answering a question of Erdös, Komlós proved in 1968 that almost all $$n\times n$$ Bernoulli matrices are nonsingular as $$n\rightarrow \infty $$ . In this paper,...     

Electrochemical Iodine-Mediated Oxidation of Enamino-Esters to 2H-Azirine-2-Carboxylates Supported by Design of Experiments

An electrochemical iodine-mediated transformation of enamino-esters for the synthesis of 2H-azirine-2-carboxylates is presented. In addition, a thermic conversion of azirines to 4-carboxy-oxazoles in quantitative yield without purification was described. Both classes 2H-azirines-2-carboxylates and the 4-carboxy-oxazoles are substructures in natural products and therefore are of considerable interest for synthetic and pharmaceutical chemists. The optimization was not performed in a conventional manner with a one-factor-at-a-time process but with a Design of Experiments (DoE) approach. Beside a broad substrate scope the reaction was also employed to a robustness screen, a sensitivity assessment, and complemented with mechanistic considerations from cyclic voltammetry experiments.     

Facile fabrication and characterization of polyimide nanofiber reinforced photocured hybrid electrolyte for Li‐ion batteries

In this study, a novel ion conductive polyimide (PI) nanofiber reinforced photocured hybrid electrolyte has been fabricated. Polyimide fibers were fabricated with the reaction between 4,4′‐oxydianiline (ODA) and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) followed by electrospinning and thermal imidization methods. Then, PI electrospun fibers were dipped into hybrid resin formulation containing bisphenol A ethoxylate dimethacrylate (BEMA), poly (ethylene glycol) methyl ether methacrylate (PEGMA) and 3‐(methacryloyloxy) propyltrimethoxysilane (MEMO) and then photocured to prepare PI nanofiber reinforced electrolyte membrane. Photocured membranes were soaked into lithium hexafluorophosphate (LiPF₆) before measuring electrochemical stability and ionic conductivity of hybrid polyelectrolyte. The chemical structure and electrochemical performance of the electrolytes were examined by Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV) and scanning electron microscopy (SEM) analysis. The incorporation of MEMO into organic matrix effectively increased the modulus from 2.83 to 5.91 MPa. The obtained results showed that a suitable electrolyte for Li‐ion batteries with high lithium uptake ratio, high conductivity (7.2 × 10^?3 S cm^?1) at ambient temperature and wide stability window above 5.5 V had been prepared. Copyright © 2017 John Wiley & Sons, Ltd.     

Anionic water-soluble sulfonated phthalocyanines: microwave-assisted synthesis,aggregation behaviours,electrochemical and in-situ spectroelectrochemical characterisation

In this work, a phthalonitrile derivative bearing p-sulfonylphenoxy group at the 3-position has been synthesised. The water-soluble non-peripherally tetrasubstituted zinc (3) and cobalt (4) phthalocyanines were obtained by cyclotetramerisation of this phthalonitrile derivative in the presence of anhydrous metal salts by microwave irradiation. The compounds have been characterised by using FT-IR, ¹H NMR, UV–Vis and Mass spectrometry (MS) data. The aggregation behaviours of these compounds were investigated in methanol, DMSO, DMF, and water. We have also studied the aggregation behaviours of the phthalocyanine complex 3 in various DMSO/water mixtures. Additionally, the redox properties of the phthalocyanine complexes were examined in dimethylsulfoxide by voltammetry and in situ spectroelectrochemistry. Redox behaviours of the complexes supported the structures of the complexes. Metal and ring-based reductions were observed for 4 and only ring-based electron transfer processes were observed with 3.     

Synthesis,characterization, crystal structure,and antimicrobial studies of 2-morpholinoethyl-substituted benzimidazolium salts and their silver(I)-N-heterocyclic carbene complexes

Research on Chemical Intermediates - This article describes synthesis of N-morpholinoethylbenzimidazole (1), 2-morpholinoethyl-substituted benzimidazolium salts (NHC precursors, 2a–c), and...     

On two classes of approximation processes of integral type

The paper aims to study two classes of linear positive operators representing modifications of Picard and Gauss operators. The new operators reproduce both constants and a given exponential function. Approximation properties in polynomial weighted spaces are investigated and the speed of convergence is measured using a certain weighted modulus of smoothness. Also, the asymptotic behavior of the integral operators are established. Finally, aspects on generalized convexity are analyzed.

     

Enamines of 1,3-dimethylbarbiturates and their symmetrical palladium(II) complexes: synthesis,characterization and biological activity

Transition Metal Chemistry - Three 1,3-dimethylbarbiturate-enamine derivatives and their symmetrical palladium(II) complexes were prepared and characterized by spectroscopic methods. In addition,...     

Experimental investigation of mixed convection heat transfer of nanofluids in a circular microchannel with different inclination angles

Journal of Thermal Analysis and Calorimetry - In this study, the characteristics of mixed convection heat transfer of nanofluids in circular microchannels with 500 μm diameter were...     

Effective binuclear Pd(II) complexes for Suzuki reactions in water

A series of new ionic binuclear Pd(II) complexes supported by water‐soluble bis(α‐diimine) ligands were prepared and employed as catalysts for the palladium‐catalyzed Suzuki reaction in aqueous media. The binuclear nature of the complexes increased the reaction rate, while electronic and steric modification of the ligand frameworks had a remarkable influence upon the catalytic activity of the palladium complexes. The catalysts were shown to be homogeneous through mercury poisoning experiments and complexes could be recycled more than 10 times without loss of catalytic activity. Copyright © 2013 John Wiley & Sons, Ltd.