Results in physics 

About: Results in physics is an academic journal published by Elsevier BV. The journal publishes majorly in the area(s): Nonlinear system & Computer science. It has an ISSN identifier of 2211-3797. It is also open access. Over the lifetime, 5762 publications have been published receiving 86425 citations.

Fractal calculus and its geometrical explanation

Abstract: Fractal calculus is very simple but extremely effective to deal with phenomena in hierarchical or porous media. Its operation is almost same with that by the advanced calculus, making it much accessible to all non-mathematicians. This paper begins with the basic concept of fractal gradient of temperature, i.e., the temperature change between two points in a fractal medium, to reveal the basic properties of fractal calculus. The fractal velocity and fractal material derivative are then introduced to deduce laws for fluid mechanics and heat conduction in fractal space. Conservation of mass in a fractal space is geometrically explained, and an approximate transform of a fractal space on a smaller scale into its continuous partner on a larger scale is illustrated by a nanofiber membrane, which is smooth on any observable scales, but its air permeability has to studied in a nano scale, under such a small scale, the nanofiber membrane becomes a porous one. Finally an example is given to explain cocoon’s heat-proof property, which cannot be unveiled by advanced calculus.

Heat transfer enhancement with Ag–CuO/water hybrid nanofluid

Abstract: Nanofluids are of great importance to researchers as they have significant uses industrially due to their high heat transfer rates. Recently, a new class of nanofluid, “hybrid nanofluid” is being used to further enhance the heat transfer rate. This new model in 3D is employed to examine the impact of thermal radiation, heat generation and chemical reaction over stretching sheet in the presence of rotation. It is concluded from the current research that even in the presence of radiation, heat generation and chemical reaction the heat transfer rate of Hybrid nanofluid is higher than the simple nanofluid.

Control of the shape and size of iron oxide (α-Fe2O3) nanoparticles synthesized through the chemical precipitation method

Abstract: Hematite (α-Fe 2 O 3 ) nanoparticles were synthesized via a simple chemical precipitation method. The impact of varying the concentration of precursor on the crystalline phase, size and morphology of α-Fe 2 O 3 products was explored. The characteristic of the synthesized hematite nanoparticles were evaluated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR) spectroscopy, Raman spectroscopy, Differential Thermal Analysis (DTA), Thermo Gravimetric Analysis (TGA), Ultraviolet–Visible (UV–Vis) analysis and Photoluminescence (PL). XRD data revealed a rhombohedral (hexagonal) structure with the space group R -3 c in all samples. Uniform spherical like morphology was confirmed by TEM and SEM. The result revealed that the particle sizes were varied between 21 and 82 nm and that the increase in precursor concentration (FeCl 3 , 6H 2 O) is accompanied by an increase in the particle size of 21 nm for pure α-Fe 2 O 3 synthesized with [Fe 3+ ] = 0.05 M at 82 nm for pure α-Fe 2 O 3 synthesized with [Fe 3+ ] = 0.4 M. FT-IR confirms the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we have synthesized pure hematite but also to identify their phonon modes. The thermal behavior of compound was studied by using TGA/DTA results: The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. Besides, the optical investigation revealed that samples have an optical gap of about 2.1 eV and that this value varies as a function of the precursor concentration.

Hall and ion slip effects on MHD rotating boundary layer flow of nanofluid past an infinite vertical plate embedded in a porous medium

Abstract: The diffusion-thermo, radiation-absorption and Hall and ion slip effects on MHD free convective rotating flow of nano-fluids (Ag and TiO2) past a semi-infinite permeable moving plate with constant heat source are discussed. Making use of Perturbation technique, we found velocity, temperature and concentration and are discussed through graphs. We evaluated the skin friction, Nusselt number and Sherwood number analytically and computationally discussed. The resultant velocity reduces with increasing rotation parameter and enhances with increasing Hall and ion slip parameters and Dufour parameter. Radiation-absorption parameter leads to increase the thermal boundary layer thickness. Nusselt number decreases with suction parameter and Sherwood number increases chemical reaction parameter.

WITHDRAWN: Preparation and characterization of high surface area activated carbon from Fox nut (Euryale ferox) shell by chemical activation with H3PO4

Abstract: Activated carbons were prepared from Fox nutshell by chemical activation with H 3 PO 4 in N 2 atmosphere and their characteristics were studied. The effects of activation temperature and impregnation ratio were examined. N 2 adsorption isotherms characterized the surface area, total pore volume, micropore volume and pore size distribution of activated carbons. Activated carbon was produced at 700 °C with a 1.5 impregnation ratio and one hour of activation time has found 2636 m 2 /g and 1.53 cm 3 /g of highest BET surface area and total pore volume, respectively. The result of Fourier-infrared spectroscopy analysis of the prepared activated carbon confirmed that the carbon has abundant functional groups on the surface. Field emission scanning electron micrographs of the prepared activated carbon showed that a porous structure formed during activation.