Control the corrosion of mild steel using synthesized polymers based on polyacrylamide

In this work polyacrylamide (PACM) was prepared by radical polymerization technique using ammonium persulfate (APS) as initiator under nitrogen atmosphere. The viscosity average molecular weight of the prepared PACM was found to be 177858. The free amino groups of PACM, poly(2-methoxyaniline) was grafted by the oxidation of 2-methoxyaniline using APS in acidic medium under nitrogen atmosphere. The grafting percent is found to be 96%. The morphology of the obtained PACM and PACM-g-P2-MeOANI was studied by X-ray diffraction and scanning electron microscope. The grafting process enhances the morphology of both PACM and poly(2-methoxyaniline). The inhibiting effect of the three polymers on the mild steel corrosion in the 1.0?M HCl as aggressive environments have been measured gravimetrically at three different temperatures 25, 40 and 55?°C and electrically at 25?°C. The inhibition efficiencies of the three tested polymers were found to increase with temperature. The poly(2-methoxyaniline) is the most effective one as a corrosion inhibitor at all tested temperatures. The adsorption behavior of the polymers was found to follow Villamil isotherm and the values of the change in free energy refer to a mixed chemical and physical adsorption on the steel surface. Tafel curves indicate that the tested polymers act as mixed anodic and cathodic inhibitor. The double layer capacitance was found to decrease with increasing the inhibitor concentration.     

A semi-analytical solution for free vibration of variable thickness two-directional-functionally graded plates on elastic foundations

The present paper investigates free vibration of variable thickness two-directional-functionally graded circular plates, resting on elastic foundations. The results are obtained for clamped, free, and simply supported edge conditions. Variations of the material and geometrical parameters are monitored by five distinct exponential functions. Therefore, the resulted non-dimensional solution may be used for a wide range of the practical problems. Mindlin’s plate theory and the differential transformation technique are used to obtain the governing equations of the natural frequencies of the circular plates. Effects of variations of the material properties in the radial and thickness directions, geometric parameters (e.g., the thickness-to-radius ratio in the center of the plate), stiffness parameters of the foundation, and various boundary conditions on the natural frequencies are investigated. Results reveal that by choosing a suitable combination of the material properties, the free vibration behavior of the thick plates may be enhanced without the need to change the geometric parameters.     

Synthesis of MoS2 nanoparticle deposited graphene/mesoporous MnOx nanocomposite for high performance super capacitor application

The present study deal with the fabrication of low cost nanocomposite based electrodes based on Nickel foam binder free substrate for supercapacitor applications. The composition of nanocomposite is molybdenum sulphide nanoparticle/graphene coated on mesoporous manganese oxide. The first step is to involve the preparation of mesoporous manganese oxide by non-ionic surfactant assisted method. In the second stage is to deposit the reduced graphene on mesoporous manganese oxide in the presence of ultrasonic irradiation followed by addition of known quantity of commercial MoS₂ nanopowder (particle size below 90 nm). The manganese oxide based nanocomposite is showing porous architecture with graphene sheet formation together with MoS₂ nanoparticle deposition. N₂ adsorption-desorption Isotherm curves for MoS₂ nanoparticle (NP) modified graphene oxide/meso-MnO₂ and pure meso-MnO₂ displayed type IV isotherm with improved surface area values. The reduced graphene oxide (graphene) and MoS₂ exist in the form of glassy flaky morphology as well as tubular/needle shapes are obtained after the deposition process in the final nanocomposite. The orderly arranged and anchored nano-sized mesoporous manganese oxide nanocomposites are showed increased specific capacitance (up to 527, 727 and 1160 F/g) and continuous cyclic stability.     

Surface and Biological Activity of Some Prepared Iminium Surfactants Based on Schiff Bases

A series of novel iminium surfactants were prepared through quaternization of different prepared fatty Schiff bases with benzyl chloride. The chemical structures were confirmed using FTIR, ¹H-NMR and mass spectroscopy. The surface properties and biological activity of these surfactants were investigated. The surface parameters including critical micelle concentration (CMC), maximum surface excess (Γ_max) and minimum surface area (A _min), Efficiency (PC₂₀) and Effectiveness (π_CMC) as well as the free energy of micellization ( $ \Updelta G_{\text{mic}}^{\text{o}} $ ) and adsorption ( $ \Updelta G_{\text{ads}}^{\text{o}} $ ) were calculated. It was found that the prepared compounds have good surface and biological activity.     

Warm Deformation Microstructure of a Plain Carbon Steel

 Grain refinement in a plain carbon steel under intercritical warm deformation was studied by torsion testing. Based on the experimental results, the warm flow behaviour and microstructural evolution of ferrite were researched with particular emphasis on the effect of the strain rate in controlling the grain refinement mechanism of ferrite. The deformed microstructures were investigated at various strain rates using optical microscopy and electron back-scattered diffraction (EBSD). The EBSD observations indicate that an increase in the strain rate leads to the development of new fine ferrite grains with high angle boundaries. Furthermore, it shows that the annihilation of dislocations occurs more readily at lower strain rate. The elongated ferrite grains continuously dynamically recrystallize to form the equiaxed fine ferrite grains. Thereby, the aspect ratio of elongated grains decreases with increasing the strain rate. Furthermore, the peak stress and steady state stress of ferrite both increase with increasing strain rate. Based on the study, the effect of strain rate on the development of fine ferrite grains during continuous dynamic recrystallization of ferrite was analyzed in detail.     

A multi-variate heart disease optimization and recognition framework

Neural Computing and Applications - Cardiovascular diseases (CVD) are the most widely spread diseases all over the world among the common chronic diseases. CVD represents one of the main causes of...     

Biased estimates of variance components

Relative bias comparison between the PSD-MINQMBE (Positive Semi Definite Minimum Norm Quadratic Minimum Biased Estimates) introduced by Hartung (1981) and the BNNQE (Biased Non Negative Quadratic Estimates) introduced by Chauby (1983) for σ²_a in the unbalanced one way random effect model with two groups are investigated. The values of the efficiency of the MINQUE (Minimum Norm Quadratic Unbiased Estimate) introduced by Rao (1971) of σ²_a relative to PSD-MINQMBE BNNQE are studied.     

An improved pseudospectral meshless radial point interpolation (PSMRPI) method for 3D wave equation with variable coefficients

In this paper, a pseudospectral meshless radial point interpolation (PSMRPI) technique is applied to the three-dimensional wave equation with variable coefficients subject to given appropriate initial and Dirichlet boundary conditions. The present method is a kind of combination of meshless methods and spectral collocation techniques. The point interpolation method along with the radial basis functions is used to construct the shape functions as the basis functions in the frame of the spectral collocation methods. These basis functions will have Kronecker delta function property, as well as unitary possession. In the proposed method, operational matrices of higher order derivatives are constructed and then applied. The merit of this innovative method is that, it does not require any kind of integration locally or globally over sub-domains, as it is essential in meshless methods based on Galerkin weak forms, such as element-free Galerkin and meshless local Petrov–Galerkin methods. Therefore, computational cost of PSMRPI method is low. Further, it is proved that the procedure is stable with respect to the time variable over some conditions on the 3D wave model, and the convergence of the technique is revealed. These latest claims are also shown in the numerical examples, which demonstrate that PSMRPI provides excellent rate of convergence.

     

Degradation kinetics of poly(ethylene terephthalate) and poly (methyl methacrylate) blends

Summary Poly(ethylene terephthalate) PET and poly(methyl methacrylate) PMMA blends were made by melt mixing in a batch reactor. Three different weight ratios of PET : PMMA (25:75, 50:50 and 75:25) were chosen to study the effect of blend composition on the degradation kinetics. A relationship between the fractional volatiles evolved per unit time and the fraction of polymer degraded is established. The kinetic parameters for degradation were found using modified Avrami’s non-isothermal equation. Parameters like degradation rate constant (k) and order of degradation (n), were evaluated for the virgin polymers and the blends.