Yazar "Rashwan, Mohammed A." seçeneğine göre listele

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    Mineralogical constituents and radioactivity analysis of commercial granitic ornamental stones: Assessing suitability and radiation safety
    (Elsevier, 2023) Lasheen, El Saeed R.; Awad, Hamdy A.; Ene, Antoaneta; Alarifi, Saad S.; Rashwan, Mohammed A.; Kawady, Nilly A.; Issa, Shams A. M.
    Several commercial granitic rocks are widely used as decorative material (ornamental stones) due to their durability and fantastic colors. The present study aims to identify the mineralogical constituents as well as natural radioactivity of seven granitic rocks known as Gandonna, Pink Granite, Fantazia, Buff granites I, Buff granites II, Qusseir brown, red granites in order to deduce their suitability for different applications (decorative stone). Accordingly, in the petrographic investigation, the examined rocks comprise different proportions of essential minerals (potash feldspar, quartz, and albite) with some secondary minerals such as kaolinite and chlorite minerals. 238U, 226Ra, 232Th and 40K activity concentrations were detected by using NaI (Tl) scintillation & gamma;-ray technique. Fantasia (av. 4.13 & PLUSMN; 5.85, 10.77 & PLUSMN; 1.9 Bqkg ? 1), and Gandonna (av. 12.4 & PLUSMN; 10.12, 35.01 & PLUSMN; 3.81 Bqkg ? 1) samples have the lowest mean 238U, and 232Th activities value, relative to other rock samples, which are lower than the recommended levels of UNSCEAR. Except for absorbed dose rate, numerous radiological indices such as outdoor and indoor annual effective dose, radium equivalent activity, external and internal indices, excess lifetime cancer risk and organs of effective dose are calculated for the examined stations to deduce the radiation effects on human organs. The obtained results reveal that the natural gamma radiation from these rocks is within acceptable limits.
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    Physico-mechanical properties and shielding efficiency in relation to mineralogical and geochemical compositions of Um Had granitoid, Central Eastern Desert, Egypt
    (Frontiers Media Sa, 2023) Rashwan, Mohammed A.; Lasheen, El Saeed R.; Abdelwahab, Wael; Azer, Mokhles K.; Zakaly, Hesham M. H.; Alarifi, Saad S.; Ene, Antoaneta
    The current work aims to describe the physico-mechanical characteristics and shielding efficiency with reference to the mineralogical and geochemical compositions of the Neoproterozoic Um Had composite granitoid pluton in order to deduce their favorability as dimension stones. The Um Had granitoid pluton has an elliptical outline with a mean diameter of about 10 km. This pluton is a composite (ranging from white to reddish pink color), hard, massive, and medium- to coarse-grained granitoid body. It is classified as syenogranite according to their modal and bulk chemical compositions. Geochemically, the granitoid pluton is a highly calc-alkaline, peraluminous granite, formed by low degree partial melting of tonalitic source rock in a post-collisional tectonic setting. The physico-mechanical properties of the granitoid pluton under study satisfy the requirements of dimension stone in terms of their bulk density (from 2561 to 2564 kg/m3), and to some extent water absorption capacity (from 0.38% to 0.55%). However, their compressive strength values (50.4-113.4 MPa) do not achieve the minimum requirement for interior use and light duty exterior use. This study delves into the potential of some of our syenogranite samples (I, IIA, IIS, and 10) as gamma radiation shielding materials. We have assessed the mass attenuation coefficient (GMAC), effective atomic number (Zeff), exposure build-up factor (EBF), and energy absorption build-up factor (EABF) for each of these samples. The GMAC and Zeff calculations were performed using the Phy-X online software, across a photon energy range of 0.015-15 MeV. Our findings suggest an inverse relationship between photon energy and GMAC, with the highest values observed for the (I) granite sample (& SIM;18). This study shows the promising radiation shielding capacity of our samples. The insights derived from GMAC, Zeff, EBF, and EABF can serve as a guide for the development of effective, naturally sourced radiation shielding materials.