Nanocrystalline Zn1-xCuxFe2O4 ferrites with x = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.50 were prepared by microwave assisted combustion method using metal nitrates and glycine as a fuel. Structural properties of the as-synthesized powders were characterized by X-ray diffraction patterns (XRD). The magnetic properties were measured using vibrating sample magnetometer (VSM). XRD analysis indicates the prepared samples are highly crystalline and they have fine structure, where their crystallite sizes are in the nanoscale range from 20-40 nm. The Saturation magnetization (Ms) and magnetic moment show an increase with Cu content (x) up to x = 0.2 reached to about 58 emu/g, and then it decreases slightly. The catalytic performance for the as prepared samples was carried out using dehydration-dehydrogenation of isopropanol. The results revealed that the catalytic conversion of isopropanol increases with Cu substitution. The isopropanol conversion reached to about 99% with 76% and 24% yields of acetone and propene respectively.

Nanocrystalline Zn1-xCuxFe2O4 ferrites with x = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.50 were prepared by microwave assisted combustion method using metal nitrates and glycine as a fuel. Structural properties of the as-synthesized powders were characterized by X-ray diffraction patterns (XRD). The magnetic properties were measured using vibrating sample magnetometer (VSM). XRD analysis indicates the prepared samples are highly crystalline and they have fine structure, where their crystallite sizes are in the nanoscale range from 20-40 nm. The Saturation magnetization (Ms) and magnetic moment show an increase with Cu content (x) up to x = 0.2 reached to about 58 emu/g, and then it decreases slightly. The catalytic performance for the as prepared samples was carried out using dehydration-dehydrogenation of isopropanol. The results revealed that the catalytic conversion of isopropanol increases with Cu substitution. The isopropanol conversion reached to about 99% with 76% and 24% yields of acetone and propene respectively.

Nanocrystalline Zn1-xCuxFe2O4 ferrites with x = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.50 were prepared by microwave assisted combustion method using metal nitrates and glycine as a fuel. Structural properties of the as-synthesized powders were characterized by X-ray diffraction patterns (XRD). The magnetic properties were measured using vibrating sample magnetometer (VSM). XRD analysis indicates the prepared samples are highly crystalline and they have fine structure, where their crystallite sizes are in the nanoscale range from 20-40 nm. The Saturation magnetization (Ms) and magnetic moment show an increase with Cu content (x) up to x = 0.2 reached to about 58 emu/g, and then it decreases slightly. The catalytic performance for the as prepared samples was carried out using dehydration-dehydrogenation of isopropanol. The results revealed that the catalytic conversion of isopropanol increases with Cu substitution. The isopropanol conversion reached to about 99% with 76% and 24% yields of acetone and propene respectively.

Zinc ferrite nano-crystals were synthesized by a microwave assisted combustion route with varying the urea to metal nitrates (U/N) molar ratio The process takes only a few minutes to obtain Zinc ferrite powders. The Effect of U/N ratio on the obtained phases, particle size, magnetization and structural properties has been investigated. The specimens were characterized by XRD, Mossbauer and VSM techniques. The sample prepared with ¨ urea/metal nitrate ratio of 1/1 was a poorly crystalline phase with very small crystallite size. A second phase is also detected in the sample. The crystallite size increases while the second phase decrease with increasing the urea ratio. The saturation magnetization and coercivity of the as prepared nano-particles changed with the change of the U/N ratio. The powder with the highest U/N ratio showed the presence of an unusually high saturation magnetization of 16 emu/g at room temperature. The crystallinity of the as prepared powder was developed by annealing the samples at 700 ◦C and 900 ◦C. Both the saturation magnetization (Ms) and the remnant magnetization (Mr) were found to be highly dependent upon the annealing temperature. Mossbauer studies show magnetic ordering in the powder even at room temperature.

Zinc ferrite nano-crystals were synthesized by a microwave assisted combustion route with varying the urea to metal nitrates (U/N) molar ratio The process takes only a few minutes to obtain Zinc ferrite powders. The Effect of U/N ratio on the obtained phases, particle size, magnetization and structural properties has been investigated. The specimens were characterized by XRD, Mossbauer and VSM techniques. The sample prepared with ¨ urea/metal nitrate ratio of 1/1 was a poorly crystalline phase with very small crystallite size. A second phase is also detected in the sample. The crystallite size increases while the second phase decrease with increasing the urea ratio. The saturation magnetization and coercivity of the as prepared nano-particles changed with the change of the U/N ratio. The powder with the highest U/N ratio showed the presence of an unusually high saturation magnetization of 16 emu/g at room temperature. The crystallinity of the as prepared powder was developed by annealing the samples at 700 ◦C and 900 ◦C. Both the saturation magnetization (Ms) and the remnant magnetization (Mr) were found to be highly dependent upon the annealing temperature. Mossbauer studies show magnetic ordering in the powder even at room temperature.

Studying the properties of plasma have received great interest in both astrophysical and laboratory plasma applicatio n. The aim of this work is to calculate the triplet distribution functions for three-component dilute relativistic plasma model. We consider here a dilut e hot plasma which is homogeneous and in equilibrium in the framework of classical relativistic statistical mechanics. Distribution functions are r epresented in the forms of a convergent series expansion in terms of the plasma thermal parameter µ in these distributions where µ = mc^2 / KT, m is the typical mass of the particles, c is the speed of light, K is the Boltzmann’s constant and T is the absolute Temperature.

Studying the properties of plasma have received great interest in both astrophysical and laboratory plasma applicatio n. The aim of this work is to calculate the triplet distribution functions for three-component dilute relativistic plasma model. We consider here a dilut e hot plasma which is homogeneous and in equilibrium in the framework of classical relativistic statistical mechanics. Distribution functions are r epresented in the forms of a convergent series expansion in terms of the plasma thermal parameter µ in these distributions where µ = mc^2 / KT, m is the typical mass of the particles, c is the speed of light, K is the Boltzmann’s constant and T is the absolute Temperature.

In this article, we study the effect of variable viscosity on the flow and vortex instability of non-Darcian free convection boundary layer flow on a horizontal surface in a saturated porous medium. The wall temperature is a power function of the distance from the origin. The variation of viscosity is expressed as an exponential function of temperature. The transformed boundary layer equations, which are developed using a non similar solution approach, are solved by means of a finite difference method. The analysis of the disturbance flow is based on linear stability theory. The local Nusselt number, critical Rayleigh number and the associated wave number at the onset of vortex instability are presented over a wide range of wall to ambient viscosity ratio parameters μ*= μw/μ∞. The variable viscosity effect is found to enhance the heat transfer rate and destabilize the flow for liquid heating, while the opposite trend is true for gas heating.

We study the effect of variable viscosity on the flow and vortex instability for non-Darcy mixed convection boundary layer flow on a nonisothermal horizontal plat surface in a saturated porous medium. The variation of viscosity is expressed as an exponential function of temperature. The analysis of the disturbance flow is based on linear stability theory. The base flow equations and the resulting eigenvalue problem are solved using finite difference schemes. It is found that the variable viscosity effect enhances the heat transfer rate and destabilizes the flow for liquid heating,while the opposite trend is true for gas heating.

In the present work, an analysis has been carried out to study a problem of natural convection past a vertical porous plate, in a porous medium saturated by a nanofluid with the streamwise distance x. The employed mathematical model for the nanofluid takes into account the effects of Brownian motion and thermophoresis. The Darcy model is employed for the porous medium. Non-similar solution has been obtained. This solution depends on a Lewis number Le, a buoyancy-ratio number Nr, a Brownian motion number Nb and a thermophoresis number Nt. The variation of the reduced Nusselt number with Nr, Nb and Nt is expressed by correlation formulas. The dependency of the Nusselt umber on these four parameters and the effect of suction and injection are investigated graphicly. It is shown that the inclusion of a nanoparticle into the base fluid of this problem is capable to change the flow pattern.