Numerical Solution of Coupled System of Nonlinear Partial Differential Equations Using Laplace-Adomian Decomposition Method

Aim of the paper is to investigate applications of Laplace Adomian Decomposition Method (LADM) on nonlinear physical problems. Some coupled system of non-linear partial differential equations (NLPDEs) are considered and solved numerically using LADM. The results obtained by LADM are compared with those obtained by standard and modified Adomian Decomposition Methods. The behavior of the numerical solution is shown through graphs. It is observed that LADM is an effective method with high accuracy with less number of components

Electrocatalytic Evolution of Oxygen Gas at Cobalt Oxide Nanoparticles Modified Electrodes

The electrocatalysis of oxygen evolution reaction (OER) at cobalt oxide nanoparticles (nano-CoOx) modified GC, Au and Pt electrodes has been examined using cyclic voltammetry. The OER is significantly enhanced upon modification of the electrodes with nano-CoOx, as demonstrated by a negative shift in the polarization curves at the nano-CoOx modified electrodes compared to that obtained at the unmodified ones. Scanning electron microscopy (SEM) revealed the electrodeposition of nanometer-size CoOx (average particle size of 200 nm) onto GC electrode. Optimization of the operating experimental conditions (i.e., solution pH and loading level of nano-CoOx) has been achieved to maximize the electrocatalytic activity of nano-CoOx modified electrodes. It has been found that the electrocatalytic activity of the nano-CoOx modified electrodes towards the OER is pH and loading level dependent, while it is substrate independent. The low cost as well as the marked stability of the thus-modified electrodes make them promising candidates in industrial water electrolysis proces

An efficient green ionic liquid for the corrosion inhibition of reinforcement steel in neutral and alkaline highly saline simulated concrete pore solutions

The effect of the green ionic liquid compound, Quaternium-32 (Q-32), on the corrosion inhibition performance of reinforcement steel, in a simulated concrete pore solution, was investigated at different temperatures and pH values, using electrochemical impedance spectroscopy (EIS). The inhibition efficiency was improved as the concentration of Q-32 and pH values were increased. However, it decreased as the temperature was raised. A Q-32 concentration of 20 µmol L–1 exhibited a 94% inhibition efficiency at 20 °C. The adsorption isotherm was evaluated using EIS measurements, and it was found to obey the Langmuir isotherm. The surface topography was examined using an atomic force microscope and scanning electron microscope. The effect of the Q-32 concentration with the highest corrosion efficiency on the mechanical properties of the mortars was also explained by flexure and compression techniques.The authors express their gratitude to the Center for Advanced Materials at Qatar University for technical support. Additionally, the authors are grateful to Qatar University for funding this work through the QUCG-CAM-20/21-2 Grant. The publication of this article was funded by the Qatar National Library

Electrospun highly corrosion-resistant polystyrene–nickel oxide superhydrophobic nanocomposite coating

A key challenge in producing superhydrophobic coatings (SHC) is to tailor the surface morphology on the micro-nanometer scale. In this work, a feasible and straightforward route was employed to manufacture polystyrene/nickel oxide (PSN) nanocomposite superhydrophobic coatings on aluminum alloys to mitigate their corrosion in a saline environment. Different techniques were employed to explore the influence of the addition of NiO nanoparticles to the as-prepared coatings. PSN-2 composite with ~ 4.3 wt% of NiO exhibited the highest water contact angle (WCA) of 155° ± 2 and contact angle hysteresis (CAH) of 5°. Graphic abstract: EIS Nyquist plots of 3 g of electrospun polystyrene coatings (a) without and with (b) 0.1, (c) 0.15, and (d) 0.2 g of NiO. [Figure not available: see fulltext.

Reforming Fiscal Institutions in Resource-Rich Arab Economies: Policy Proposals

This paper traces the evolution of fiscal institutions of Resource Rich Arab Economies (RRAEs) over time since their pre-oil days, through the discovery of oil to their build-up of oil exports. It then identifies challenges faced by RRAEs and variations in their severity among the different countries over time. Finally, it articulates specific policy reforms, which, if implemented successfully, could help to overcome these challenges. In some cases, however, these policy proposals may give rise to important trade-offs that will have to be evaluated carefully in individual cases

Application of Effective Semi-Analytical Algorithms for Neutral and Retarded Volterra Integrodifferential Equations

This study developed three semi-analytical algorithms to solve functional integrodifferential equations with variable delays under initial conditions. These algorithms embrace the Laplace Adomian decomposition method (LADM), the modified Laplace Adomian decomposition method (MLADM), and the Laplace variational iteration method (LVIM). Using the suggested approaches, we find the solutions without discretization, transformation, or limiting traditions while considering suitable initial conditions. In addition, the solutions are generated in fast-converging series with easily calculable terms. The proposed methodologies are tested numerically on three numerical applications to prove their efficacy and dependability as well as to compare their computational efficiency. Based on the numerical results, it is evident that the procedures offered are both effective and correc

Numerical approaches to system of fractional partial differential equations

In this paper, by introducing the fractional derivative in sense of Caputo, the Laplace- variational iteration method (LVIM) and the Laplace-Adomian decomposition method (LADM) are directly extended to study the linear and nonlinear systems of fractional partial differential equations, as a result the approximated numerical solutions are acquired in the form of rapidly convergent series with easily computable components. Numerical results show that the two approaches are easy to implement and accurate when are applied. Compassions are made between the two methods and exact solutions. Figures are used to show the efficiency as well as the accuracy of the achieved approximated results

Electrocatalysis of the Oxygen Evolution Reaction at Nickel Oxide Nanoparticles - Modified Electrodes

Electrocatalysis, the approach dealing with enhancing the rates of electrochemical reactions by altering the surface properties of the electrodes on which these reactions proceed has been a topic of rapidly increasing interest. An intensive effort has recently been invested to develop new electrocatalytic materials for several applications such as the anodic oxygen evolution reaction (OER). The OER is principal in water electrolysis, an auxiliary reaction in the production of several substances forming at the cathode, and a side reaction in a number of anodic processes, particularly in the production of chlorine and other oxidizing agents. The recent revolution in nanotechnology has stimulated the development of a large set of novel nano-sized materials for the OER. The use of nano-sized electrodes enhances the mass transport, enlarges the accessible active surface area, lowers the charged currents and reduces the deleterious effects of solution resistance. Herein, we report on the electrocatalytic applications of platinum (Pt), gold (Au) and glassy carbon (GC) electrodes modified with nickel oxide (NiOx) nanoparticles towards the OER. The modification of the electrodes with NiOx nanoparticles has been done electrochemically. The scanning electron microscope (SEM) and the Energy dispersive X-ray spectroscopy (EDXS) are used to evaluate the surface morphology and composition of the modified electrodes. Preliminary results revealed a significant enhancement in the electrocatalytic activity of the GC and Au electrodes towards the OER upon the modification with NiOx nanoparticles. This enhancement appeared in a cathodic shift of 750 mV and 550 mV in the onset potentials of the OER, respectively, on the NiOx-modified GC and Au electrodes

Flower-shaped gold nanoparticles: Preparation, characterization, and electro

The modification of a glassy carbon electrode with gold nanoparticles was pursued, characterized, and examined for electrocatalytic applications. The fabrication process of this electrode involved assembling the gold nanoparticles atop of amino group grafted glassy carbon electrode. The scanning electron microscopy indicated the deposition of gold nanoparticles in flower-shaped nanostructures with an average particle size of ca. 150 nm. Interestingly, the electrode exhibited outstanding enhancement in the electrocatalytic activity toward the oxygen evolution reaction, which reflected from the large negative shift (ca. 0.8 V) in its onset potential, in comparison with that observed at the bulk unmodified glassy carbon and gold electrodes. Alternatively, the Tafel plot of the modified electrode revealed a significant increase (∼one order of magnitude) in the apparent exchange current density of the oxygen evolution reaction upon the modification, which infers a faster charge transfer. Kinetically, gold nanoparticles are believed to facilitate a favorable adsorption of OH− (fundamental step in oxygen evolution reaction), which allows the charge transfer at reasonably lower anodic polarizations