Surfactant for better tomorrow: applied aspect of surfactant aggregates from laboratory to industry

Research on Chemical Intermediates - Surfactant is a special kind of amphiphilic compound composed of water-loving and hating parts. The remarkable physical properties like interfacial tension,...     

The examination of molecular structure properties of 4,4′-oxydiphthalonitrile compound: combined spectral and computational analysis approaches

The synthesis process, X-ray diffraction analysis of its single crystal form and the structural properties of the 4,4′-oxydiphthalonitrile compound by Fourier transform infrared, nuclear magnetic resonance and ultraviolet-visible spectral methods were reported in this study. Density functional theory studies of the compound were carried out by designed modeling with the Becke three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional and 6-311G(d,p) basis set. Some molecular structure parameters obtained theoretically were compared with those obtained from the crystallographic analysis. Vibrational modes and wavenumbers with the aid of the potential energy distribution analysis, carbon and proton chemical shift values with diversified approaches and absorption wavelengths using Time-Dependent Density Functional and Conductor-Like Polarizable Continuum Model in different solvent media were examined theoretically. The compatibility of spectral and theoretical results was evaluated by examining the correlation coefficients. In addition, the frontier molecular orbitals energies, global reactivity parameters, molecular electrostatic potential map, the potential for non-linear optical material and some thermodynamic parameters at different temperature values of the 4,4'-oxydiphthalonitrile compound were investigated at the same theoretical level.     

Monitoring Humic Acid Photodegradation by CUPRAC Colorimetric and HPLC Determination of Dihydroxybenzoate Isomers Produced From a Salicylate Probe

Abstract

Novel analytical methods were designed for monitoring humic acid photodegradation in environmental waters. Modified CUPric Reducing Antioxidant Capacity (CUPRAC) spectrophotometric and chromatographic methods were used for the determination of dihydroxybenzoate isomers (DHBAs) produced from a salicylate probe, which was hydroxylated by hydroxyl radicals (^?OH) produced from the photodegradation of humic acid under ultraviolet A-radiation. The combined use of CUPRAC colorimetry and HPLC was shown to effectively monitor humic acid photodegradation and ^?OH generation for the first time. The formation of 2,5-dihydroxybenzoate and 2,3-dihydroxybenzoate, as major and minor products, respectively, from the hydroxylation of a salicylate probe was demonstrated by HPLC and confirmed by a modified CUPRAC method to indicate ^?OH formation from humic acid, which acted as both a generator and absorber of hydroxyl radicals. Salicylate hydroxylation showed an increase between 30 and 50?min of illumination, and was affected by the initial concentration of humic acid up to 0.01% but not by solution pH around the neutral values. Traces of Fe(III) and Mn(II) present in natural waters decreased the ^?OH production, but EDTA partly restored the probe hydroxylation by chelating these metal cations. Since humic acid-mediated ^?OH generation may aid in natural disinfection processes, this work may extend our comprehension of concentration- and time-dependent generation of ^?OH in environmental waters and of the possible effects of other antioxidants.     

Simulation and analysis of the impact of micron-scale particles onto a rough surface

Normal impact of micron-scale copper particles onto a rough copper surface is investigated in the 25–150 m/s impact velocity range, by the finite element method. Surface roughness is generated numerically and incorporated into the finite element model. Particle size is varied in a range comparable to the magnitude of the standard deviation of the surface roughness. Isotropic hardening with strain rate effects and thermal softening due to plastic heat dissipation are included in the model. Analysis is carried out in plane strain mode and impact of single and multiple particles are modeled. The effects of surface roughness on the mechanics of impact, energy exchange, rebound characteristics of the particle and the residual stresses in the substrate are investigated. Impacts on peaks and valleys cause response similar to oblique impact, affecting the rebound behavior of the particle by changing the rebound direction and increasing the rebound energy of the particle. Impacts also cause surface smoothening by crushing the surface peaks; however, collapse of adjacent peaks can provoke stress concentrations and initiate crack formation. Influence of surface roughness on the aftermath of particle impacts decreases with increasing particle size and impact velocity. For impact velocities higher than 50 m/s, no significant difference is observed between impact on smooth and rough surfaces in terms of residual stress generation in the substrate. In general, it is concluded that the effect of surface roughness should be taken into account for low velocity impacts where only the surface peaks deform, or for small particles with size comparable to the standard deviation of the surface roughness.     

Synthesis,characterization and catalytic activity in Suzuki–Miyaura coupling of palladacycle complexes with n‐butyl‐substituted N‐heterocyclic carbene ligands

A series of monomeric palladacycle complexes bearing n‐butyl‐substituted N‐heterocyclic carbenes, namely [Pd(NHC)X(dmba)] (dmba: dimethylbenzylamine and [Pd(NHC)X(ppy)]; NHC: 1‐n‐butyl‐3‐substituted benzylimidazol‐2‐ylidene; ppy: 2‐phenylpyridine), were prepared either by transmetallation from the corresponding silver carbene complexes or by the reaction of the corresponding acetate‐bridged palladacycle dimer with N‐heterocyclic carbene ligands in high yields. The palladium(II) complexes were characterized using elemental analyses, APCI‐MS, ¹H NMR and ¹³C NMR spectroscopies. These complexes are efficient in the Suzuki–Miyaura coupling reaction between phenylboronic acid and aryl bromides.     

Investigation of radon concentrations in some reservoirs,spring and tap waters in İstanbul,Turkey

Journal of Radioanalytical and Nuclear Chemistry - The 222Rn activity in water samples from reservoirs, springs and taps in the area of Istanbul, Turkey has been measured with an AlphaGUARD system....     

Solitons for perturbed Gerdjikov–Ivanov equation in optical fibers and PCF by extended Kudryashov’s method

This paper reveals bright, dark and singular soliton solutions to the perturbed Gerdjikov–Ivanov equation by the aid of extended Kudryashov’s method. The nonlinear terms appear with full nonlinearity in order to give a generalized flavor to the model. As a byproduct of this scheme, plane waves and singular periodic solutions fall out and these solutions are listed as well.     

Dihydropyridazine-appended dibenzosuberenones as a new class of fluorophores: Application to fluoride sensing

Highly fluorescent, novel dihydropyridazine-appended dibenzosuberenone type dye molecules were obtained in a single step from simple compounds using Diels-Alder chemistry. This new fluorophore structure can be used for the construction of fluorescent chemosensors, as exemplified by selective and sensitive fluoride ion sensing. The –N–H protons in these structures are acidic enough to allow for fluoride-induced deprotonation, leading to a significant color change as well as a concomitant fluorescence quenching. These fluorophores possess large Stokes shifts, high quantum yields, and long fluorescence lifetimes; therefore, this study potentially paves the way for the construction of novel dye molecules for use in fluorescent dye applications.