A Passerini/Tsuji-Trost access to dienamide derivatives

The Passerini reaction of α, β-unsaturated aldehydes affords allylic acetates which may be involved in Tsuji-Trost elimations towards conjugated dienamides. The interest of these 2,4-dienamides has been demonstrated in several TiCl₄ triggered Diels-Alder reactions with N-phenylmaleimide.     

Synthesis,characterization and X-ray crystal structure of novel nickel Schiff base complexes and investigation of their catalytic activity in the electrocatalytic reduction of alkyl and aryl halides

Novel potentially bidentate NO Schiff base ligands, HL ¹ and HL ² derived from condensation reaction of 2′-methoxyphenyl-2-ethylamine with salicylaldehyde (HL ¹ ) and with 2-hydroxy-4-methoxybenzaldehyde (HL ² ), and their nickel complexes were synthesized and characterized by usual spectroscopic techniques such as FT-IR, UV–Vis, ¹H NMR, ¹³C NMR and elemental analysis. It was revealed that the bidentate Schiff base ligands coordinate with Ni(II) ions yielding mononuclear complexes with 1:2 (metal/ligand) stoichiometry. This result has been determined by using X-ray crystallographic technique of HL ² and the nickel complex derived from HL ¹ (Ni(II)-2L ¹ ). So, the structural studies showed that the two Ni(II) complexes adopt a square-planar geometry around the central metal ion. Cyclic voltammetry studies were investigated in 0.1 M TBAP in DMF solution and indicate that the nickel complexes show one reduction wave related to Ni(II)/Ni(I) redox couple. The electrocatalytical properties of these complexes were also studied in the same electrolyte medium. Their electrocatalytic performances have been tested toward the electroreduction reaction of bromocyclopentane and iodobenzene, showing a promoted activity in the case of the Ni(II)-2L ² complex.     

Synthesis,spectroscopic characterization,crystal structure and theoretical investigation of two azo-palladium (II) complexes derived from substituted (1-phenylazo)-2-naphtol

Transition Metal Chemistry - The ortho-substituted (E)-1-((2-methoxyphenyl)diazenyl)naphthalen-2-ol and the meta-substituted (E)-1-((3-methoxyphenyl)diazenyl)naphthalen-2-ol were, respectively,...     

Ammonium ionic liquid as modulator of the critical micelle concentration of ammonium surfactant at aqueous solution: conductimetric and dynamic light scattering (DLS) studies

We report measurements of self aggregation in aqueous solution of an ionic liquid (IL), didecyl-dimethylammonium nitrate ([DDA][NO(3)]) and a surfactant hexadecyl-trimethylammonium bromide (CTAB) and of mixtures of these two salts. The electrical conductivity and dynamic light scattering (DLS) measurements were used for the characterization of the aggregation process. The conductivity measurements were performed at three temperatures. The critical micelle concentration (CMC) was determined at different temperatures and at different ratio of two salts. The effect of IL on the micellization of CTAB has been discussed. Our results suggest that organized structures formed by CTAB and [DDA][NO(3)] self assembly in domains of several hundred nanometers size. The micellar solubility of the salicylic acid in mixed salt aqueous solutions was determined to probe the physical properties of these assemblies. We have observed, that the micellar solubility enhancement was only slightly influenced by the nature of micelles present in aqueous solution. This proves that salicylic acid solubilization is enthalpy driven.     

Magnetic Fe2O3-polystyrene/PPy core/shell particles: bioreactivity and self-assembly

This paper describes the synthesis of new magnetic, reactive polystyrene/polypyrrole core/shell latex particles. The core consists of a polystyrene microsphere containing gamma-Fe2O3 superparamagnetic nanoparticles (PSmag), and the shell is made of reactive N-carboxylic acid-functionalized polypyrrole (PPyCOOH). These PSmag-PPyCOOH latex particles, average diameter 220 nm, were prepared by copolymerization of pyrrole (Py) and the active carboxyl-functionalized pyrrole (PyCOOH) in the presence of PSmag particles. PNVP was used as a steric stabilizer. The functionalized polypyrrole-coated PSmag particles were characterized in terms of their particle size, surface morphology, chemical composition, and electrochemical and magnetic properties using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry, and SQUID magnetometry. Activation of the particle surface carboxyl groups was achieved using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS), which helps transform the carboxyl groups into activated ester groups (NSE). The activated particles, PSmag-PPyNSE, were further evaluated as bioadsorbents of biotin used as a model biomolecule. It was shown that biotin was immobilized at the surface of the PSmag-PPyNSE particles by forming interfacial amide groups. The assemblies of PSmag-PPyCOOH particles on glass plates were further investigated. When no magnetic field is applied, the particles assemble into 3D colloidal crystals. In contrast, under a magnetic field, one-particle-thick chains gathered in hedgehog-like architectures are obtained. Furthermore, PSmag-PPyCOOH coated ITO electrodes were shown to be electroactive and electrochemically stable, thus offering potentialities for creating novel high-specific-area materials for biosensing devices where the conducting polymer component would act as the transducer through its conductive properties.     

MIGAN: Mutual-Interaction Graph Attention Network for Collaborative Filtering

Many web platforms now include recommender systems. Network representation learning has been a successful approach for building these efficient recommender systems. However, learning the mutual influence of nodes in the network is challenging. Indeed, it carries collaborative signals accounting for complex user-item interactions on user decisions. For this purpose, in this paper, we develop a Mutual Interaction Graph Attention Network “MIGAN”, a new algorithm based on self-supervised representation learning on a large-scale bipartite graph (BGNN). Experimental investigation with real-world data demonstrates that MIGAN compares favorably with the baselines in terms of prediction accuracy and recommendation efficiency.     

Prediction of forming limits for porous materials using void-size dependent model and bifurcation approach

Meccanica - The scientific literature has shown the strong effect of void size on material response. Several yield functions have been developed to incorporate the void size effects in ductile...     

Solitons in PT-symmetric potential with competing nonlinearity

We investigate the effect of competing nonlinearities on beam dynamics in PT-symmetric potentials. In particular, we consider the stationary nonlinear Schrödinger equation (NLSE) in one dimension with competing cubic and generalized nonlinearity in the presence of a PT-symmetric potential. Closed form solutions for localized states are obtained. These solitons are shown to be stable over a wide range of potential parameters. The transverse power flow associated with these complex solitons is also examined.     

Analytical prediction of damage in the composite part of a type-3 hydrogen storage vessel

The damage behavior of a type-3 hydrogen storage vessel is modeled. The vessel consists of a metal envelop, called liner, coated with a filament winding. The model proposed allows simulating the mechanical response of the structure to a quasi-static loading. The model is based on a meso-macro approach and takes into account the damage behavior of the composite and the elastoplastic deformation of the liner. The results obtained are compared with experimental data. Finally, the effect of stacking sequence of filament layers on the damage level in the composite is investigated.     

A macroion correlation effect on the structure of charged stabilized colloidal suspensions: a self-consistent integral equation study

Using the mean field Poisson–Boltzmann (PB) and the Ornstein–Zernike (OZ) integral equation theories, we have determined the macroions effective interactions and the structure of charged stabilized colloidal suspension for a large charge range of macroion and screening parameter values. The renormalized parameters are calculated by solving the PB equation written in the framework of the modified Jellium model. The structures have been determined by solving the OZ equation coupled with a self-consistent integral equation, which is related to the Verlet’s modified closure. Our results of the effective parameters are in good agreement with the experimental data, also the structure presents acceptable improvement compared to the Monte Carlo simulation data, against the HNC structure results, PACS: 61.20 Gy, 82.70 Dd, and 82.70 Kj.