Evaluation of Gamma Radiation Properties of Four Types of Surgical Stainless Steel in the Energy Range of 17.50-25.29 keV.

In this study, the gamma radiation properties of four types of surgical-grade stainless steel (304, 304L, 316 and 316L) were investigated. The effective atomic number Zeff, effective electron density Neff and half-value layer (HVL) of four types of surgical-grade stainless steel were determined via the mass attenuation coefficient (µ/ρ). The µ/ρ coefficients were determined experimentally using an X-ray fluorescence (XRF) technique and theoretically via the WinXCOM program. The Kα1 of XRF photons in the energy range between 17.50 and 25.29 keV was used from pure metal plates of molybdenum (Mo), palladium (Pd), silver (Ag) and tin (Sn). A comparison between the experimental and theoretical values of µ/ρ revealed that the experimental values were lower than the theoretical calculations. The relative differences between the theoretical and experimental values were found to decrease with increasing photon energy. The lowest percentage difference between the experimental and theoretical values of µ/ρ was between -6.17% and -9.76% and was obtained at a photon energy of 25.29 keV. Sample 316L showed the highest value of µ/ρ at the energies 21.20, 22.19 and 25.29 keV. In addition, the measured results of Zeff and Neff for all samples behaved similarly in the given energy range and were found to be in good agreement with the calculations. The equivalent atomic number (Zeff) of the investigated stainless-steel samples was calculated using the interpolation method to compare the samples at the same source energy. The 316L stainless steel had higher values of µ/ρ, Zeff and Zeq and lower values of HVL compared with the other samples. Therefore, it is concluded that the 316L sample is more effective in absorbing gamma radiation.

The Potentials of Egyptian and Indian Granites for Protection of Ionizing Radiation.

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.

Measurements of surface air 7Be concentrations in Saudi Arabia.

The main objective of this study is to identify the atmospheric 7Be concentrations in 130 surface air samples collected from three stations located in Riyadh, Haql and Khafji cities in Saudi Arabia between November 2012 and April 2014. Monthly variations as well as seasonal patterns of 7Be were studied using a medium-volume air sampler and a gamma spectroscopy system equipped with a high-purity germanium (HPGe) detector. 7Be exhibited one maximum specific activity in summer and one minimum in winter with average monthly concentrations of 12.4 ± 0.9, 15.4 ± 1.2, and 18.0 ± 1.3 mBq m-3 in Riyadh, Haql and Khafji, respectively. Overall, the average 7Be concentration in the three stations was 12.9 ± 1.0 mBq m-3, whereas the maximum value of 29.5 mBq m-3 was registered in Khafji city in August 2013. Besides 7Be, measurements indicate observations of 40 K, 137Cs, 226Ra radionuclides in surface air samples collected from the three stations. 40 K showed measurable concentrations, whereas the concentrations of 137Cs and 226Ra were only detected in a limited number of samples.

Gamma radiation and indoor radon concentrations in the western and southwestern regions of Saudi Arabia.

The exposure of the population to natural gamma radiation in air and to indoor radon gas was investigated in Makkah, AlBaha, Assir, Jazan and Najran regions in the western and southwestern of Saudi Arabia. The survey was performed by using LiF:Mg,Cu,P thermoluminescence dosimeters (TLDs) for indoor and outdoor absorbed dose rates in air measurements in 885 locations, and a passive integrating ionizing system, equipped with an E-Perm Electret ion chamber, for radon concentration measurements in a total of 1119 dwellings. The ambient indoor rates vary from 54 to 191 nSv h-1, while it is in the range of 42-112 nSv h-1 for the outdoor. The indoor and outdoor rates of the directional dose equivalent ranged from 56 to 185 nSv h-1 and from 43 to 135 nSv h-1, respectively. Makkah region showed the highest mean indoor ambient and directional rates, whereas Assir region showed the highest mean outdoor rates. The indoor and outdoor gamma dose rates were significantly correlated. On the other hand, the indoor radon concentrations ranged from 11 to 137 Bq m-3 with an overall mean of 32 Bq m-3 for all investigated houses. The overall annual mean effective dose rate from radon and its decay progenies was estimated to be 0.76 mSv y-1, which yields an excess lifetime cancer risk of around 2.3 × 10-3.

Study on the radioactivity and soil-to-plant transfer factor of (226)Ra, (234)U and (238)U radionuclides in irrigated farms from the northwestern Saudi Arabia.

The present study addresses the soil-to-plant transfer factors (TFs) of (226)Ra, (234)U and (238)U for 13 types of vegetables and agricultural crops planted under semi-arid environment in the northwestern part of Saudi Arabia. Crop plants along with plant-growing soils were collected from selected farms, which are irrigated from the non-renewable Saq aquifer, and investigated for their radioactivity content by means of alpha spectrometry after applying a radiochemical separation procedure. Hence, TF data for plant roots, green parts (stem and leaves) and fruits were calculated and contrasted to those reported in the literature. Substantial differences were observed in the TFs of Ra and U radioisotopes among plant species. In crop fruits, eggplant exhibited the highest uptake of (226)Ra (TF value of 0.11), while beans (0.16) have the highest TF for (234)U and (238)U. The geometric mean TF values indicated that the crop roots tend to accumulate Ra and U about four to six-folds higher than fruits. The relation between TF values and soil concentrations showed a weak correlation. Activity ratios between radionuclides in crop plants indicated the preferential translocation of U in fruits than Ra even though Ra is more available for root uptake. The fruit/root (F/R) ratios obtained for the investigated plants shown that pepper had the smallest F/R ratios (0.07 ± 0.01, 0.12 ± 0.02 and 0.11 ± 0.02 for (226)Ra, (234)U and (238)U, respectively), while the highest F/R ratios were observed in potatoes (0.71 ± 0.15, 0.44 ± 0.10 and 0.40 ± 0.08 for (226)Ra, (234)U and (238)U, respectively). The TF and F/R ratios data of natural radionuclides in the study region can hopefully improve the scientific knowledge for future studies.

Determination of natural radioactivity in irrigation water of drilled wells in northwestern Saudi Arabia.

The levels of natural radiation in bedrock groundwater extracted from drilled wells in selected farms in the northwestern part of Saudi Arabia were addressed. The investigated waters form a source of irrigation for vegetables, agricultural crops, wheat, and alfalfa to feed livestock consumed by the general public. Information about water radioactivity in this area is not available yet. Therefore, this study strives to contribute to the quality assessment of the groundwater of these wells that are drilled into the non-renewable Saq sandstone aquifer. Hence, gross alpha and beta activities as well as the concentrations of (224)Ra, (226)Ra, (228)Ra, (234)U, (238)U, and U(total) were measured, compared to national and international limits and contrasted with data quoted from the literature. Correlations between the activities of the analyzed radionuclides were discussed. The concentrations of gross alpha and beta activities as well as (228)Ra were identified by liquid scintillation counting whereas alpha spectrometry was used to determine (224)Ra, (226)Ra, (234)U and (238)U after separation from the matrix by extraction chromatography. The mean activity concentrations of gross α and ß were 3.15 ± 0.26 Bq L(-1) and 5.39 ± 0.44 Bq L(-1), respectively. Radium isotopes ((228)Ra and (226)Ra) showed mean concentrations of 3.16 ± 0.17 Bq L(-1) and 1.12 ± 0.07 Bq L(-1), respectively, whereas lower levels of uranium isotopes ((234)U and (238)U) were obtained.

Observation on symmetry properties of sodium zinc(II)-2,9,16,23-phthalocyanine tetracarboxylate in water:NaOH solution.

The shift of the Q-band of sodium zinc(II)-2,9,16,23-phthalocyanine tetracarboxylate (ZnPc(COONa)4) to about 800 nm is attributed to the influence of the electron-donating property of the carboxylate groups substituted in the ß-position. ZnPc(COONa)4 which was found to have a symmetry of D 2h characterized by a splitting of the Q transition. This splitting was interpreted by the formation of dianionic symmetric ZnPc(COONa)4 resulting from the dissociation of the pyrrole protons as well as the possibility of Na(+) dissolution of ZnPc(COONa)4 in the aqueous solution of NaOH.

Natural radioactivity in tap water and associated age-dependent dose and lifetime risk assessment in Amman, Jordan.

With the aim of assessing potential public impact, preliminary investigations on tap waters collected from highly populated areas in Amman and Aqaba, Jordan were conducted by measuring gross alpha and beta activities as well as uranium and radium radionuclides. Gross activities deduced by liquid scintillation counting (LSC) were ranged in <50-250 ± 23 mBq l(-1) for alpha and <188-327 ± 29 mBq l(-1) for beta in Amman whereas higher concentrations were found in Aqaba. The results show that gross ß activities are generally higher than the corresponding gross α activities and direct correlations between gross activities and total dissolved solids (TDS) exist. Moreover, the effect of TDS on gross analyses was studied and devoted to the optimization of LSC parameters. (234)U, (235)U and (238)U concentrations were determined by alpha spectrometry after separation from the matrix by extraction chromatography and electroplating. (226)Ra and (228)Ra concentrations were measured, respectively, using de-gassing and gas proportional counter techniques. Uranium and radium concentrations do not reach the WHO recommended levels and the radioisotopic activity ratios were discussed. The associated age-dependent dose from water ingestion in Amman was estimated. The total dose for adults had an average value of 0.15 mSv y(-1), which exceeds the WHO recommended limit of 0.1 mSv y(-1) but still below the Jordanian limit of 0.5 mSv y(-1). Although the Jordanian limit was exceeded for babies and infants, the lifetime risk assessment showed values as low as 10(-4). Thereby it is concluded that tap waters of Amman is radiologically safe and pose no significant hazard to the public. Finally, a comparison of the investigated waters with worldwide data was made.

Natural radioactivity, dose assessment and uranium uptake by agricultural crops at Khan Al-Zabeeb, Jordan.

Khan Al-Zabeeb, an irrigated cultivated area lies above a superficial uranium deposits, is regularly used to produce vegetables and fruits consumed by the public. Both soil and plant samples collected from the study area were investigated for their natural radioactivity to determine the uranium uptake by crops and hence to estimate the effective dose equivalent to human consumption. Concentrations of (238)U, (235)U, (232)Th, (226)Ra, (222)Rn, (137)Cs and (40)K in nine soil profiles were measured by gamma-ray spectrometry whereas watermelon and zucchini crops were analyzed for their uranium content by means of alpha spectrometry after radiochemical separation. Correlations between measured radionuclides were made and their activity ratios were determined to evaluate their geochemical behavior in the soil profiles. Calculated soil-plant transfer factors indicate that the green parts (leaves, stems and roots) of the studied crops tend to accumulate uranium about two orders of magnitude higher than the fruits. The maximum dose from ingestion of 1 kg of watermelon pulp was estimated to be 3.1 and 4.7 nSv y(-1) for (238)U and (234)U, respectively. Estimations of the annual effective dose equivalent due to external exposure showed extremely low values. Radium equivalent activity and external hazard index were seen to exceed the permissible limits of 370 Bq kg(-1) and 1, respectively.