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    A comprehensive evaluation of the attenuation characteristics of some sliding bearing alloys under 0.015–15 meV gamma-ray exposure
    (MDPI, 2022) Algethami, Merfat; Ibraheem, Awad A.; Issa, Shams A. M.; Tekin, Hüseyin Ozan; Ene, Antoaneta; Pyshkina, Maria; Rashad, Mohamed; Almisned, Ghada; Zakaly, Hesham M. H.
    In this study, three different sliding bearing alloy samples were investigated in terms of their performance on attenuation characteristics and behavioral attitudes under 0.015–15 MeV gamma-ray exposure. Accordingly, different types of advanced calculation methods were utilized to calculate the radiation shielding parameters. Next, several gamma-ray shielding parameters and exposure rates in addition to fast neutron removal cross-section were determined. Furthermore, exposure and energy absorption buildup factors were determined by using G-P fitting method. Mass attenuation coefficients (MAC) values were recorded as 2.5246, 2.5703, and 2.5827 (cm2 /g) for Alloy1, Alloy2, and Alloy3 samples at 15 MeV photon energy, respectively. At 40 mfp, the highest EBF values were reported as 1,376,274, 1,003,593, and 969,373 for Alloy1, Alloy2, and Alloy3 samples. The results of this extended investigation showed that the Alloy3 sample with the highest Pb reinforcement amount has superior shielding capability among the investigated samples. It can be concluded from the results that substitution of Pb with Bi in the recent alloy structure has a monotonic effect on different types of shielding parameters. Therefore, it can also be concluded that Pb is a remarkable tool for the improvement of the shielding properties of studied alloy structures. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
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    Heavy metal oxide (HMO) glasses as an effective member of glass shield family: A comprehensive characterization on gamma ray shielding properties of various structures
    (Elsevier Editora Ltda, 2022) Tekin, Hüseyin Ozan; Susoy, Gülfem; Issa, Shams A.M.; Ene, Antoaneta; ALMisned, Ghada; Rammah, Y.S.; Ali Fatema, T.; Algethami, Merfat; Zakaly, Hesham M.H.
    Using advanced Monte Carlo simulation techniques and theoretical methodologies, a thorough investigation on the gamma-ray shielding properties of several heavy metal oxide glasses were performed. The general-purpose Monte Carlo code MCNPX (version 2.7.0) was used to simulate gamma-ray transmission to determine fundamental attenuation coefficients. The acquired findings were compared to Phy-X/PSD to confirm that the outputs were consistent. Additionally, other gamma-ray shielding parameters were computed and studied throughout a broad photon energy range of 0.015 MeV–15 MeV. From A to F glass samples, a sharp density increase from 5.99 g/cm3 to 8.9 g/cm3 was found. As a result, the F sample was found to have the highest linear attenuation coefficients. Our results indicate that increasing the amount of Bi reinforcement improved the material's overall gamma-ray attenuation properties. The F sample with the highest Bi reinforcement in its glass structure was subsequently shown to have superior gamma-ray shielding characteristics. Finally, we compared the F sample's half-value layer values to those of other commercial glass shields, various concretes, and other glass shields investigated in the literature. As a consequence of the benchmarking procedure, it has been determined that the F sample has better shielding capabilities than other shielding materials. It can be concluded that heavy metal oxide glasses offer apparent benefits in terms of more efficiently attenuating incoming gamma-rays. Additionally, it can be concluded that applying high Bi to heavy metal oxide glasses is a beneficial strategy for improving the gamma-ray attenuation capabilities of heavy metal oxide glasses. © 2022 The Author(s)
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    Nuclear power plant biological complications on marine biota from a probabilistic accident - a case study
    (Pergamon-elsevier science LTD, 2024) Abbasi, Akbar; Mirekhtiary, Fatemeh; Issa, Shams A. M.; Algethami, Merfat; Zakaly, Hesham M. H.
    An accident at the Barakah Nuclear Power Plant (BNPP) would result in a significant radionuclide release into the semi-closed marine environment. In this research, the released radionuclide distribution pattern and dose rate in the Persian/Arabian (Gulf) were calculated using a combined hydrodynamic/radiobiological model. Simulations of the dispersion of artificial radionuclide concentrations were conducted using a HYSPLIT model. To assess prospective hazards in case of an incident, environmental risk from ionizing contaminants: assessment and management (ERICA) tools were used. Using the Fukushima nuclear power accident as a model, the scenario source term profile was developed. The volumetric concentrations levels of pollutants ranged between 1 x 104 mBq m- 3 to 1 x 1010 mBq m- 3 in the radius of 200 km after 48 h. Based on the dose rates of the various marine biotas, Polychaete worms, and Pelagic fish, they had the highest and lowest dose contribution.
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    Radioactivity concentration levels and potential radiotoxicity risk assessment of aquatic superfoods case study of algae supplements
    (Pergamon-elsevier science ltd, 2024) Abbasi, Akbar; Issa, Shams A. M.; Mirekhtiary, Fatemeh; Algethami, Merfat; Zakaly, Hesham M. H.
    It has been found that algae have a variety of health benefits, although investigations showed that they contain radiotoxic elements, including Ra-226, Th-232, K-40, and Cs-137, which may affect human health. This study is connected to activity concentration measurements of the above radionuclides in the algae supplements available in the Middle East markets. The annual effective radiation doses of measured radionuclides in analyzed algal supplements have been calculated. The highest values of annual effective doses have been estimated for Ra-226 in Ecklonia (13.39 mu Sv/y) and for Th-232 in Red Marine Algae (11.80 mu Sv/y), both from South Korea. In algal superfoods, the effective dose of Cs-137 is not significantly affected by the Fukushima Nuclear Power Plant. Based on these results, it can be concluded that the activity levels of radionuclides are low, the naturally occurring radionuclides provide the most effective doses, and algae supplements can be considered safe.
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    Radiotoxic concentrations and risk levels along the world's coastlines during the quarter of a century
    (Elsevier B.V., 2025) Abbasi, Akbar; Algethami, Merfat; Zakaly, Hesham M.H.; Mirekhtiary, Fatemeh
    The radioactivity contamination of marine environments polluted by natural and anthropogenic radionuclides has been discussed for decades worldwide. However, there is a lack of data on the current situation and trends in this research field. For this reason, this is the first study to report an integrated data statistical analysis of radioactivity concentration mapping and systematic review using the published database from 2000 to date. The study encompassed five continents: Asia, Africa, Oceania, Europe, and America. The primary sources of natural radioactivity were 226Ra, 232Th, and 40K, which are associated with geological features such as coastal structures and the seabed. Also, the contamination of anthropogenic radionuclide 137Cs is reported in some places that are released by nuclear reactions. The annual dose rate was proved to be the basis for assessing the radiation risk of natural radioactivity. This research outcome is useful for pointing out the need for future research and supporting the development of this topic. © 2024 Elsevier B.V.
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    Structural, linear/nonlinear optical characteristics and radiation shielding effectiveness of Cu4O3/Cu2O dual-phase thin films: Influence of oxygen flow rate in reactive sputtering process
    (Elsevier ltd, 2024) Issa, Shams A. M.; Hassan, Ahmed M.; Algethami, Merfat; Zakaly, Hesham M.H.
    In the present work, we investigated the impact of oxygen flow rate on the structural, linear, and nonlinear optical characteristics while also evaluating the radiation shielding effectiveness during reactive radio frequency (rf) sputtering in the deposition of Cu4O3/Cu2O dual-phase thin films. Microstructural analysis revealed distinct changes with increased OFRs, switching from a Cu2O cubic structure phase to a Cu4O3 tetragonal structure phase. The XRD patterns revealed good crystallinity, and the crystallite size of the film reduced from 28 nm to 22 nm, and the microstrain exhibited an opposing trend as the oxygen flow rate increased. In contrast, investigating the optical properties of dual-phase Cu4O3 and Cu2O thin films using UV-Vis-NIR spectroscopy revealed intriguing trends in the absorbance spectra, absorption coefficient, and extension index. The apparent bandgap increases from 2.0 eV to 2.62 eV with increasing oxygen flow rates. In addition, nonlinear optical parameters, including the nonlinear refractive index n(2) linear, nonlinear sensitivity (chi(1) and chi(3)), and nonlinear absorption coefficient beta(c) were calculated to demonstrate the applicability of these materials. The dual-phase structure of the films enhances their potential for effective radiation shielding. Our findings provide valuable insights into the design of properties of Cu4O3/Cu2O dual-phase thin films for applications ranging from photoelectric and nonlinear optical devices to radiation shielding effectiveness.