A new surface structural approach to ion adsorption: tracing the location of electrolyte ions

Electrolyte ions differ in size leading to the possibility that the distance of closest approach to a charged surface differs for different ions. So far, ions bound as outersphere complexes have been treated as point charges present at one or two electrostatic plane(s). However, in a multicomponent system, each electrolyte ion may have its own distance of approach and corresponding electrostatic plane with an ion-specific capacitance. It is preferable to make the capacitance of the compact part of the double layer a general characteristic of the solid-solution interface. A new surface structural approach is presented that may account for variation in size of electrolyte ions. In this approach, the location of the charge of the outersphere surface complexes is described using the concept of charge distribution in which the ion charge is allowed to be distributed over two electrostatic planes. It was shown that the concept can successfully describe the pH dependent proton binding and the shift in the isoelectric point (IEP) in the presence of variety of monovalent electrolyte ions, including Li(+), Na(+), K(+), Cs(+), Cl(-), NO(-)(3), and ClO(-)(4) with a common set of parameters. The new concept also sheds more light on the degree of hydration of the ions when present as outersphere complexes. Interpretation of the charge distribution values obtained shows that Cl(-) ions are located relatively close to the surface. The large alkali ions K(+), Cs(+), and Rb(+) are at the largest distance. Li(+), Na(+), NO(-)(3), and ClO(-)(4) are present at intermediate positions.     

Inner- and outer-sphere complexation of ions at the goethite-solution interface

Formation of inner- and outer-sphere complexes of environmentally important divalent ions on the goethite surface was examined by applying the charge distribution CD model for inner- and outer-sphere complexation. The model assumes spatial charge distribution between the surface (0-plane) and the next electrostatic plane (1-plane) for innersphere complexation and between the 1-plane and the head end of the diffuse double layer (2-plane) for the outersphere complexation. The latter approach has been used because the distance of closest approach to a charged surface may differ for different ions. The surface structural approach implies the use of a Three-Plane model for the compact part (Stern layer) of solid-solution interface, which is divided into two layers. The thickness of each layer depends on the capacitance and the local dielectric constant. The new approach has been applied to describe the adsorption of magnesium, calcium, strontium, and sulfate ions. It is shown that the concept can successfully describe the development of surface charge in the presence of Ca(+2), Mg(+2), Sr(+2), and SO4(-2) as a function of loading, pH, and salt level, and also the shift in the isoelectric point (IEP) of goethite. The CD modeling revealed that, for the conditions studied, magnesium is mainly adsorbed as a bidentate innersphere complex, calcium can be a combination of bidentate innersphere and a monodentate inner- or outer-sphere complexes, and strontium is probably adsorbed as an outersphere complex. Sulfate is present as a mixture of inner- and outer-sphere monodentate complexes. Outersphere complexation is less pH dependent than innersphere complexation. The CD model predicts that the outersphere complexation of divalent cations and anions is relatively favorable at respectively low and high pH. Increase of ion loading favors the formation of innersphere complexes.     

2‐(1H‐Benzotriazole‐1‐yl)‐1,1,3,3‐Tetramethyluronium Tetrafluoro Borate (TBTU) as an Efficient Coupling Reagent for the Esterification of Carboxylic acids with Alcohols and Phenols at Room Temperature

Esterification of carboxylic acids with alcohols and phenols by using 2‐(1H‐benzotriazole‐1‐yl)‐1,1,3,3‐tetramethyluronium tetrafluoroborate (TBTU) in the presence of triethylamine as a base proceeded smoothly under mild conditions to afford the corresponding esters in good to high yields in acetonitrile at room temperature.     

Nonlinear vibration of an electrostatically actuated micro-beam made of anelastic material considering compressible fluid media

Nonlinear Dynamics - Similar to elasticity and viscoelasticity, anelasticity is one of the rheological models of materials. Like the viscoelastic materials, anelastic deformation is time dependent,...     

Certain locally convex topologies on the discrete vector-valued Lebesgue spaces

Let Γ be a set and (E, ‖·‖ _E ) be a nontrivial Banach space. In this paper, through generalizing to vector-valued discrete Lebesgue spaces ? ¹(Γ,E), we show that the topology β ¹(Γ,E) introduced by Singh is, in fact, a type of strict topology. This observation enables us to conclude various basic properties of β ¹(Γ,E). Then, we consider the discrete semigroup algebra ? ¹(S,E) under certain locally convex topologies. As an application of our results, we show that the semigroup algebra (? ¹(S,E), β ¹(S,E)) with the convolution as multiplication is a complete semi-topological (but not topological) algebra.     

A hybrid metaheuritic technique developed for hourly load forecasting

Electricity load forecasting has become one of the most functioning tools in energy efficiency and load management and utility companies which has been made very complex due to deregulation. Due to the importance of providing a secure and economic electricty for the consumers, having a reliable and robust enough forecast engine in short‐term load management is very needful. Fuzzy inference system is one of primal branches of Artificial Intelligence techniques which has been widely used for different applications of decision making in complex systems. This paper aims to develop a Fuzzy inference system as a main forecast engine for Short term Load Forecasting (STLF) of a city in Iran. However, the optimization of this platform for this special case remains a basic problem. Hence, to address this issue, the Radial Movement Optimization (RMO) technique is proposed to optimize the whole Fuzzy platform. To support this idea, the accuracy of the proposed model is analyzed using MAPE index and an average error of 1.38% is obtained for the forecast load demand which represents the reliability of the proposed method. Finally, results achieved by this method, demonstrate that an adaptive two‐stage hybrid system consisting of Fuzzy & RMO can be an accurate and robust enough choice for STLF problems. © 2016 Wiley Periodicals, Inc. Complexity 21: 521–532, 2016     

On {phi}-contractibility of the Lebesgue–Fourier algebra of a locally compact group

For a locally compact group G, we present some characterizations for f{phi}-contractibility of the Lebesgue–Fourier algebra LA(G){mathcal{L}A(G)} endowed with convolution or pointwise product.     

Extensions of the Lax–Milgram theorem to Hilbert $$C^*$$ C ∗ -modules

Positivity - We present three versions of the Lax–Milgram theorem in the framework of Hilbert $$C^*$$ -modules, two for self-dual ones over $$W^*$$ -algebras and one for those over $$C^*$$...     

Electrochemical Sensing of Uric Acid Using a ZnO/Graphene Nanocomposite Modified Graphite Screen Printed Electrode

Russian Journal of Electrochemistry - An electrochemical sensor has been fabricated using ZnO/GR nanocomposite for selective determination of uric acid (UA) in a phosphate buffer solution (PBS, pH...     

Impact of MHD on hybrid nanomaterial free convective flow within a permeable region

Journal of Thermal Analysis and Calorimetry - Computational modeling was employed to scrutinize the nanomaterial influence of flow patterns and thermal treatment within a porous region....