Solubilization of Ni Imidazole Complex in Micellar Media of Anionic Surfactants,Sodium Dodecyl Sulfate and Sodium Stearate

The solubilization and physicochemical behavior of a coordination complex of nickel, namely [Ni(im)₆]F₂·5H₂O [hexakis(imidazole)nickel(II) fluoride pentahydrate], in aqueous micellar media of anionic surfactants, i.e., sodium dodecyl sulfate (SDS) and sodium stearate (SS), were investigated by using UV–Vis spectroscopy and electrical conductivity measurements. Spectroscopic techniques were used for the computation of binding constant (K_b), partition coefficient (K_x), change in free energy of binding (ΔG_b), and change in free energy of partition (ΔG_p), whereas electrical conductivity data was helpful to calculate thermodynamic parameters of micellization of surfactants in the presence of the Ni complex, i.e., standard entropy of micellization (ΔS_m), free energy (ΔG_m), and enthalpy of micellization (ΔH_m). It is evident from the results that solubilization of the Ni complex takes place because of electrostatic as well as hydrophobic interactions. The presence of the Ni complex in micellar media increases the critical micelle concentration of both surfactants owing to the structure‐breaking effect.     

Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 2: kinetics

The results of a detailed investigation into the kinetics of quinoline oxidation in supercritical water are presented. The novel kinetic data presented were obtained in a continuously operated, plug flow reactor where parameters such as temperature, pressure, residence time and stoichiometric ratio of oxidant to quinoline were investigated and detailed in the companion paper (Pinto LDS, Freitas dos Santos LMF, Al‐Duri B and Santos RCD, Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 1: effect of key operating parameters. J Chem Technol Biotechnol). An induction time was experimentally observed, ranging from 1.5 to 3.5 s, with longer times observed in experiments carried out at lower temperatures. A pseudo‐first‐order rate expression with respect to quinoline concentration (with oxygen excess) was first adopted and the activation energy of 234 kJ mol^?1 and a pre‐exponential factor of 2.1 × 10¹⁴ s^?1 were estimated. Furthermore, an integral power rate model expression was established, attributing a reaction order for quinoline as 1 and for oxygen as 0.36. An activation energy and pre‐exponential factor for this model were determined as 224 kJ mol^?1 and 3.68 × 10¹⁴ M^?0.36 s^?1, respectively. A global rate expression was then regressed for the quinoline reaction rate from the complete set of data. The resulting activation energy was 226 ± 19 kJ mol^?1 and the pre‐exponential factor was 2.7 × 10^{13 ± 2} M^?0.1 s^?1. The reaction orders for quinoline and oxygen were 0.8 ± 0.1 and 0.3 ± 0.1, respectively. It was shown that the least‐squares regression method provided the best‐fit model for experimental results investigated in this study. Copyright © 2006 Society of Chemical Industry     

Photo-lithographic patterning of biomimetic molecularly imprinted polymer thin films onto silicon wafers

This investigation describes the design and synthesis of molecularly imprinted polymers (MIPs) as patterned thin films, based on molecular modelling of functional monomer-template interactions and validation by NMR-spectroscopy. Several MIP thin films were prepared from a solution containing the template N-boc-l-phenylalanine and functional acrylic monomers at varying ratios with a cross-linker and initiator in a porogenic solvent. This solution was then spin-coated onto 3-(trimethoxysilyl)propyl methacrylate-functionalised silicon wafers and subsequently the film was photo-polymerised. After template extraction, the film thickness and topography of a methacrylic acid MIP was characterised with atomic force microscopy. A 4-vinylpyridine-MIP thin film was then made by depositing the pre-polymerisation solution on top of the methacrylic acid MIP by spin-coating. Photo-lithographic etching through a gold grid and extraction of non-polymerised solution from under the gold mask yielded a grid-patterned surface, in which two different MIPs alternate with dimensionality at the micro- or submicro-meter scale. Selectivity differences between the two MIP surfaces towards fluorescent template analogue N-dansyl-l-phenylalanine were documented using fluorescence microscopy. This side-by-side comparison on the same thin film allows fast and cost-effective assessment of the two very different MIP selectivities towards various biomolecules.     

New exact analytical solutions for Stokes’ first problem of Maxwell fluid with fractional derivative approach

The unsteady flow of an incompressible Maxwell fluid with fractional derivative induced by a sudden moved plate has been studied using Fourier sine and Laplace transforms. The obtained solutions for the velocity field and shear stress, written in terms of generalized G functions, are presented as sum of the similar Newtonian solutions and the corresponding non-Newtonian contributions. The non-Newtonian contributions, as expected, tend to zero for λ→0. Furthermore, the solutions for ordinary Maxwell fluid, performing the same motion, are obtained as limiting cases of general solutions and verified by comparison with previously known results. Finally, the influence of the material and the fractional parameters on the fluid motion, as well as a comparison among fractional Maxwell, ordinary Maxwell and Newtonian fluids is also analyzed by graphical illustrations.     

Image steganography for authenticity of visual contents in social networks

Multimedia Tools and Applications - Social networks are major sources of image sharing and secret messaging among the people. To date, such networks are not strictly bounded by copyright laws due...     

Synergistic evaluation of AgO2 nanoparticles with ceftriaxone against CTXM and blaSHV genes positive ESBL producing clinical strains of Uro‐pathogenic E. coli

The silver oxide nanoparticles (AgO₂ ‐NPs) were synthesised using silver foil as a new precursor in wet chemical method. X‐ray diffraction analysis shows crystallographic structures of AgO₂ ‐NPs with crystallite size of 35.54 nm well‐matched with standard cubic structure. Scanning electron microscopy analysis clearly shows the random distribution of spherical‐shaped nanoparticles. Energy dispersive X‐ray analysis confirmed the purity of the samples as it shows no impurity element. Fourier transforms infra‐red analysis confirmed the formation of AgO₂ ‐NPs with the presence of Ag‐O‐Ag stretching bond. All the techniques also confirmed the loading of ceftriaxone drug on the surface of AgO₂ ‐NPs. This study also described the effect of AgO₂ ‐NPs having synergistic activity with β lactam antibiotic i.e. ceftriaxone against ESBL generating Escherichia coli (E. coli). Among isolated strains of E. coli, 60.0% were found to be ESBL producer. The synergistic activities of AgO₂ ‐NPs with ceftriaxone suggest that these combinations are effective against MDR‐ESBL E. coli strains as evident by increase in zone sizes. The present study observed rise in MDR‐ESBL E. coli with polymorphism of blaCTXM and blaSHV causing UTI infections in Pakistani population. The antibiotic and AgO₂ ‐NPs synergistic effect can be used as an efficient approach to combat uro‐pathogenic infections.Inspec keywords: antibacterial activity, nanofabrication, nanomedicine, drugs, nanoparticles, microorganisms, crystallites, scanning electron microscopy, silver compounds, X‐ray diffraction, X‐ray chemical analysis, Fourier transform infrared spectra, organic compounds, geneticsOther keywords: synergistic evaluation, clinical strains, silver oxide nanoparticles, silver foil, wet chemical method, X‐ray diffraction analysis, crystallographic structures, standard cubic structure, spherical‐shaped nanoparticles, energy dispersive X‐ray analysis, ceftriaxone drug, synergistic activity, ESBL producer, scanning electron microscopy, Fourier transform infrared analysis, Escherichia coli, blaSHV gene positive ESBL, crystallite size, random distribution, β lactam antibiotics, MDR‐ESBL E. coli strains, polymorphism, blaCTXM, uro‐pathogenic infections, uro‐pathogenic E. coli, AgO₂      

Optimization of phototrophic hydrogen production by Rhodopseudomonas palustris PBUM001 via statistical experimental design

Phototrophic hydrogen production by indigenous purple non-sulfur bacteria, Rhodopseudomonas palustris PBUM001 from palm oil mill effluent (POME) was optimized using response surface methodology (RSM). The process parameters studied include inoculum sizes (% v/v), POME concentration (% v/v), light intensity (klux), agitation (rpm) and pH. The experimental data on cumulative hydrogen production and COD reduction were fitted into a quadratic polynomial model using response surface regression analysis. The path to optimal process conditions was determined by analyzing response surface three-dimensional surface plot and contour plot. Statistical analysis on experimental data collected following Box-Behnken design showed that 100% (v/v) POME concentration, 10% (v/v) inoculum size, light intensity at 4.0 klux, agitation rate at 250 rpm and pH of 6 were the best conditions. The maximum predicted cumulative hydrogen production and COD reduction obtained under these conditions was 1.05 ml H₂/ml POME and 31.71% respectively. Subsequent verification experiments at optimal process values gave the maximum yield of cumulative hydrogen at 0.66 ± 0.07 ml H₂/ml POME and COD reduction at 30.54 ± 9.85%.     

Equilibrium liquidus temperatures of binary mixtures from differential scanning calorimetry

The measurements of solid-liquid phase diagrams for a binary mixture using a differential scanning calorimeter are revisited in this paper. A new method employing the DSC curves and a theoretical model to detect solid-liquid equilibrium temperature of the initial mixture before freezing is proposed. The liquidus temperatures for different compositions are found to be in good agreement with the available literature data.