No abstract

No abstract

No abstract

In this work, polymer composites of high density polyethylene reinforced by micro-sized and nanosized cadmium oxide, lead oxide, and a mixture of both with filler weight fraction of 30% were prepared by compression molding technique and characterized by scanning electron microscope. This investigation aims to present a comparative study between cadmium oxide and lead oxide according to their sizes as fillers in high density polyethylene polymeric matrix for gamma-radiation shielding applications. The mass and linear attenuation coefficients of the investigated composites were measured as a function of g-ray energies ranging from 59.53 keV to 1408.01 keV using standard radioactive point sources (241Am, 133Ba, 137Cs, 60Co, and 152Eu). The measurements were made with a narrow beam geometry setup using a well calibrated hyper pure germanium cylindrical detector. The theoretical values of the mass attenuation coefficients were evaluated using the XCOM program database. The experimental results demonstrated that, according to the filler size, cadmium oxide composite is better as a gamma absorber in the energy region less than 81 keV, while lead oxide composite is better in the energy region greater than 81 keV. Moreover, for the same chemical structure and weight fraction of the composite, nano fillers show better attenuation performance than micro fillers in high density polyethylene based radiation shielding material.

A promising rotating arc discharge method has been developed for producing high purity silver carbon nanotube and zinc oxide nanoparticles, to study their capacities for methylene blue (MB) dye removal under different conditions such as contact time, initial methylene blue dye ion concentration, solution pH, and adsorbent dose. The equilibrium isotherm data were analyzed using Langmuir, Freundlich, Temkin isotherms. Correlation coefficients indicated the following order to fit isotherms for silver carbon nanotube: Freundlich > Langmuir > Temkin. On the other hand, for zinc oxide nanoparticles, the following adjustment founded to fit isotherms was: Langmuir > Temkin> Freundlich. Furthermore, separation factors and distribution coefficients of Methylene blue (MB) dye were calculated. Adsorption kinetic data were analyzed using pseudo-first and second -orders and Elovich model. Film and intraparticle Diffusion model were used to investigate Adsorption mechanism. Kinetic studies showed that the adsorption of methylene blue onto silver carbon nanotubes followed Elovich kinetic model, and the rate of adsorption is controlled by the liquid film diffusion model. Adsorption of methylene blue on zinc oxide nanoparticles followed the pseudo-second-order kinetic model, and the rate of adsorption is controlled by the intraparticle diffusion model.

This paper aims to study the radiation shielding characteristics and buildup factor of some types of granite in Egypt. The mass attenuation coefficient (MAC) for three types of granite (gandola, white halayeb, and red aswani) was experimentally determined, and the experimental results were validated by XCOM software. The relative deviation between the two methods does not exceed 3% in all discussed granite samples, which means that MAC calculated through the experimental and XCOM are in suitable agreement. The effective atomic number (Zeff) varies from 13.64 to 10.69, 13.68 to 10.59, and 13.45 and 10.66 for gandola, white halayeb, and red aswani, respectively. As well as the equivalent atomic number (Zeq) was calculated in a wide range of energy to deduce the exposure (EBF) and energy absorption (EABF) buildup factors for the studied granite materials. The linear attenuation coefficient (LAC), half-value layer (HVL), mean free path (MFP) were calculated at each investigated energy and showed that the most effective shielding ability at high energy was red aswani, while at low energy, the shielding ability was nearly constant for studied granites. The present study forms the first endeavor to obtain the radiation shielding properties of the studied materials to be used in practical applications.

Bulk superconductor samples of YBa 2 Cu 3 O 7−δ (YBCO) doped with nano metal oxides of Mn 3 O 4 , Co 3 O 4 , Cr 2 O 3 , CuO and SnO 2 respectively with 0.2 wt% are synthesized by a solid-state reaction route. The structural characterization of all samples has been carried out by x-ray diffraction (XRD) and scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The XRD patterns indicate that the magnetic doping of nano metal oxides Mn O , Co O , Cr O 3 4 3 4 2 3( ) gives a high value of orthorhombicity of the YBCO samples which is the result of high oxygen content, and consequently could give better superconducting properties contrary to the non magnetic nano oxides (CuO, SnO 2 ). The critical temperature (T c ) of the studied samples was found to improve by nano magnetic doping and lower with nano nonmagnetic doping. The superconducting transition temperature Tc determined from electrical resistivity measurements was found to increase for Mn 3 O 4 (5.27 μB) doping and decrease for other metal oxides doping.

ANGLE software for semiconductor detector efficiency calculations - long existing and widely accepted tool in quantitative gamma spectrometry - has been recently extended to scintillation NaI detectors. The extension features in the latest edition (ANGLE 4) and it is briefly outlined. Discretization of reference efficiency curve, meaning possibility of using ANGLE 4 for particular gamma energies without constructing the complete reference efficiency curve, is particularly emphasized. This yields both in enhanced practicality and higher accuracy, while reducing the potential for systematic errors. The present work is primarily focussed on experimental verification of ANGLE 4 for NaI detectors. Two detectors (2 ? 2 and 3 x 3 inches) were employed in the experiment. Commercially calibrated gamma sources (in the forms of quasi point and cylinder) and homemade solutions (diluted from calibrated ones) were measured at various distances from the detector(s), ranging 0 cm to 50 cm. Energy range observed was 59 keV to 1408 keV. Versatility of counting conditions, in terms of detectors and sources used, gamma energies observed, source detector separations, etc., was aimed at creating as large experimental evidence as possible for verification purposes. Experimentally obtained efficiencies are compared with those calculated by ANGLE 4. Very good agreement is obtained - well within the experimental uncertainties - thus proving the reliability of the software.