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1
Caridi, Francesco, Domenico Pappaterra, Giovanna Belmusto et Maurizio D'Agostino. « Radioactivity Measurements in Water : An Overview of the Actual Technologies ». Current Nutrition & ; Food Science 17, no 6 (9 juin 2021) : 548–52. http://dx.doi.org/10.2174/1573401317666210122091439.
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Among the most significant matrices in the field of environmental radioactivity, water is certainly included, being subject to monitoring and controls to safeguard the environment from possible anthropogenic contamination. The presence of radionuclides in water also constitutes a health risk to human, because its consumption increases the likelihood of incurring cancer. In authors’ laboratory, different experimental techniques were employed to measure radioactivity content of surface and drinking water, according to the Italian Legislation and to the Italian Institute for the Environmental Protection and Research (ISPRA) guidelines. Gamma spectrometry was employed to quantify the specific activity of gamma-emitters anthropogenic contaminants and natural radionuclides; liquid scintillation counting (LSC), to measure the activity concentration of tritium, radon and gross alpha and beta; total alpha/beta counting, with the thick source method, to detect about gross alpha and beta specific activity; emanometry, to estimate gas radon activity concentration.
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K, Charan Kumar. « Study of Atmospheric Instabilities through Radioactivity ». Mapana - Journal of Sciences 14, no 1 (20 juillet 2017) : 15–23. http://dx.doi.org/10.12723/mjs.32.3.
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Radon and its progeny concentration are measured at 1m height from surface of Earth in the premises of National Atmospheric Research Laboratory, Gadanki to observe the changes in activity concentration of radon particularly during instabilities that are occurring in the atmosphere. The measurements were carried out using AlphaGUARD and Alpha Progeny Meter for the measurement of radon and its progenies, respectively. It has been observed that, the changes in daily and weekly atmospheric radon levels are related to the stability or turbulence of the lower troposphere. The analysis reveals that from sunny windless days indicates growth and dissolution of the inversion layer. The study of radon concentrations during several atmospheric instabilities including period during Nilam cyclone, has shown interesting features, which are correlated with the conditions of stability or turbulence in the atmosphere.
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Elzain, Abd-Elmoniem A., Hajo Idriss, Yousif Sh Mohammed, Khidir Shaib Mohamed, Mohamed Abd Elwahab Mohamed Ali, Mohamed Musa Saad Hasb Elkhalig, Isam Salih et al. « Assessment of radioactivity from selected soil samples from Halfa Aljadida area, Sudan ». Radiochimica Acta 107, no 6 (26 juin 2019) : 489–502. http://dx.doi.org/10.1515/ract-2018-3067.
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Abstract In this research, the results of radon concentration, surface and mass exhalation rates, radium concentration, effective dose rate and the alpha index have been investigated in a number of 198 soil samples that have been collected from various residential locations of Halfa Aljadida area, Sudan. The can technique, containing CR-39 have been used. From our results, the average value of soil gas radon concentration was found to be 1.96±0.22 kBq·m−3. The average values of surface and mass exhalation rates were 1.73±0.19 Bq·m−2·h−1 and 34.79±3.87 mBq·kg−1·h−1, respectively. The radium concentration average value was 8.06±0.90 Bq·kg−1. While the average value of the effective dose rate was recorded to be 54.69±6.11 mSv·y−1. The average value of alpha index of studied samples was (4.03±0.45)×10−2. From the study, a good positive and linear correlation between radium concentration, surface and mass exhalation rates of soil samples were present. In addition to that, a positive and linear correlation between radium and radon concentrations was found. Finally, a comparison between the results and other findings was conducted and the results imply the fact that the area under consideration is safe as if the health hazard are mentioned.
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Kücükömeroglu, B., A. Kurnaz, R. Keser, F. Korkmaz, N. T. Okumusoglu, G. Karahan, C. Sen et U. Cevik. « Radioactivity in sediments and gross alpha–beta activities in surface water of Fırtına River, Turkey ». Environmental Geology 55, no 7 (8 novembre 2007) : 1483–91. http://dx.doi.org/10.1007/s00254-007-1098-7.
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Soniya, S. R., et P. J. Jojo. « Natural radioactivity assessment of surface soil collected from Poovar village of Kerala, India ». IOP Conference Series : Materials Science and Engineering 1263, no 1 (1 octobre 2022) : 012034. http://dx.doi.org/10.1088/1757-899x/1263/1/012034.
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Making use of gamma ray spectrometric analysis method, the activities of soil-borne radio-nuclides viz. 226Ra, 232Th and 40K in the surface soil samples from a specific village in coastal county has been determined. The surface soil of living environment in the Poovar village was used for the study. The activity concentration is used for evaluating various radiologically vital parameters such as levels of radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), absorbed gamma dose rate (D), outdoor and indoor annual effective dose (AED), representative gamma radioactivity level index (Iγ) and alpha index (Iα) in the region. The estimated radioactivity concentrations of 226Ra, 232Th and 40K was observed to fluctuate from below detectable level (BDL) of the instrument to 9 Bqkg−1, 21 Bqkg−1 to 36 Bqkg−1 and 453 Bqkg−1 to 585 Bqkg−1, respectively. Since all of the samples investigated in the study are within the advised limit, there are no radiation threats to the human beings in the region. The obtained information in this research can be used for future radiological mapping and impact assessments.
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Ogundare, F. O., et O. I. Adekoya. « Gross alpha and beta radioactivity in surface soil and drinkable water around a steel processing facility ». Journal of Radiation Research and Applied Sciences 8, no 3 (juillet 2015) : 411–17. http://dx.doi.org/10.1016/j.jrras.2015.02.009.
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Ito, Hiroshi, Hirohisa Ishiura, Kiseki D. Nakamura et Kentaro Miuchi. « A progress of upgrading α-ray imaging chamber in a low background radioactivity ». Journal of Physics : Conference Series 2156, no 1 (1 décembre 2021) : 012176. http://dx.doi.org/10.1088/1742-6596/2156/1/012176.
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Abstract Precise measurements of radioactive impurity concentration in the detector materials have been established for various underground particle physics experiments. It is also important to measure the surface radioactive contamination on these materials because their decay products would potentially reduce the fiducial volume of the detector and would also produce background sources via radon emanation. In this study, descriptions on an α-ray imaging chamber based on a gaseous micro-time-projection chamber are reported. A detector upgrade to improve the sensitivity by a suppression of the background rate and a demonstration of alpha-ray imagings are also described.
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Nguyen, Van Thang, Ngoc Ba Vu et Nguyen Phong Thu Huynh. « Gross alpha and beta radioactivity in food crops and surface soil from Ho Chi Minh City, Vietnam ». Journal of Radioanalytical and Nuclear Chemistry 315, no 1 (14 novembre 2017) : 65–73. http://dx.doi.org/10.1007/s10967-017-5631-1.
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Thomas, Rimon, Juan Mantero, Carlos Ruiz Cánovas, Elis Holm, Rafael García-Tenorio, Eva Forssell-Aronsson et Mats Isaksson. « Natural radioactivity and element characterization in pit lakes in Northern Sweden ». PLOS ONE 17, no 3 (31 mars 2022) : e0266002. http://dx.doi.org/10.1371/journal.pone.0266002.
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Northern Sweden has been the object of intense metal mining in the last decades producing several water-filled open-pits, or pit lakes. Most of these pit lakes have been limed to maintain a good water quality and to prevent generation of acidic water that could leach the exposed rocks and release metals into water. The aim of this work was to examine the concentration of stable elements and naturally occurring radionuclides in water and sediment samples from pit lakes originating from non-uranium mining activities in Northern Sweden. Surface water and surface sediments were collected from 27 pit lakes in Northern Sweden. Water quality parameters, concentration of stable elements and radionuclides were measured by a water probe, ICP-MS and XRF, and alpha and gamma spectrometry, respectively. Furthermore, a multivariate statistical analysis (PCA) was performed on the water samples and sediments. In general, the quality of the surface water was good, but some lakes had low pH values (2.5–5.7), and high concentrations of Fe (up to 200 mg/L) and other metals (e.g. Zn, Cu). When relating the metal concentrations in sediments in pit lakes with the concentration found in natural lakes, some sites had relatively high levels of Cu, As, Cr and Pb. The activity concentration of 210Po, and U and Th isotopes in water and sediment samples were at environmental levels, as was the ambient dose equivalent rate at these sites (range 0.08–0.14 μSv/h).
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Lewis, R. W., J. L. Harwood et R. J. Richards. « A method for preparing radiolabelled rat pulmonary surfactant ». Biochemical Journal 235, no 1 (1 avril 1986) : 75–79. http://dx.doi.org/10.1042/bj2350075.
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A method is described for the preparation of rat pulmonary surfactant, radiolabelled specifically in the phosphatidylcholine species, which may be used for degradative studies of the lipoprotein complex. Intravenously administered [methyl-14C]choline chloride is maximally incorporated into alveolar surface surfactant 8 h after injection, and more than 97% of this radiolabel is present in the phosphatidylcholine fraction of the surfactant and, of this, 75% is associated with the dipalmitoyl phosphatidylcholine species. Electron microscopy indicates that the isolated surfactant has a similar physical form to that found at the alveolar surface. The mineral alpha-quartz can be used to increase the yield of surfactant lavaged from the lung surface, but the complex isolated from rats treated in this manner has a low specific radioactivity (less than 1000 d.p.m./mg) compared with that prepared from control animals (22860 d.p.m./mg).
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NOUREDDINE, A., M. BENKRID, A. HAMMADI, R. BOUDJENOUN, M. MENACER, A. KHABER et M. S. KECIR. « Radioactivity Distribution In Surface And Core Sediment Of The Central Part Of The Algerian Coast : An Estimation Of The Recent Sedimentation Rate ». Mediterranean Marine Science 4, no 2 (1 décembre 2003) : 53. http://dx.doi.org/10.12681/mms.228.
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Sediment core samples and marine surface sediments of identical composition, mostly muddy, were collected using a Van Veen type grab and a box corer on board the M.S. Benyahia research vessel (ISMAL), along the Algerian littoral, between Algiers (36Ζ49.9 N/ 03Ζ 02.3 E) and Cherchell (36Ζ 39.4 N/ 02Ζ 12.4 E), during a sampling cruise in September 1997. The samples were analysed to determine the activity concentration of natural radionuclides (uranium and thorium series and 40 K as well) and artificial radionuclides ( 137 Cs and Pu isotopes), using a direct gamma spectrometry for gamma emitters and radiochemical separations and alpha spectrometry for alpha emitters. The horizontal and vertical distribution of the examined radionuclides were studied in the surface and core samples and an effort to estimate the sedimentation rate was attempted.The measured values range was: 17 - 26 Bq/Kg dry for uranium series radioisotopes, 18 – 32 Bq/Kg dry for thorium series radioisotopes, 311 - 690 Bq/Kg dry for 40 K, 0.4 - 11 Bq/Kg dry, for 137 Cs and 0.4 – 1.0 Bq/Kg dry for 239 + 240 Pu.
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Joseph, Deepthy Maria, Nithu Ashok et Antony Joseph. « A systematic study of proton, alpha and cluster decays in Rhenium isotopes using the effective liquid drop model ». Modern Physics Letters A 31, no 05 (5 février 2016) : 1650031. http://dx.doi.org/10.1142/s0217732316500310.
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Employing the effective liquid drop model (ELDM), half-lives of proton and alpha decays and probable cluster decays are computed and analyzed for different proton-rich and neutron-rich isotopes of Rhenium. The investigation fortifies the phenomenon of cluster radioactivity (CR) in rare earth nuclei and also affirms the pivotal role played by neutron magicity in cluster decays. ELDM data is compared with that of universal decay law (UDL) model and found to be more efficient than the latter one. Apparently, cluster emissions slacken as the neutron number of daughter nucleus goes up and the linear nature of Geiger–Nuttall (G–N) plots stays unaltered even if the surface potential is incorporated.
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Hashim, Abdalsattar Kareem, Abbas Rashid Al-Ghanimi, Sanaa Mohammed Ridha Hasan, Tamara Ali Naser et Ahmed Jumaah Mhawes. « Investigating Radioactive Content in Various Commercially available Flour Samples in Local Iraqi Markets ». NeuroQuantology 19, no 9 (12 octobre 2021) : 06–13. http://dx.doi.org/10.14704/nq.2021.19.9.nq21131.
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The study was conducted to assess the radioactivity of alpha concentration of different samples of flour in Karbala mills and some samples in local Iraqi markets. Alpha sensitive CR-39 plastic paths detectors commonly know as "Solid State Nuclear paths Detectors" were used measuring the concentrations of uranium, efficaious radium content, and ratio of radon. The results indicate that the exhalation levels of mass and surface radon were between 0.214-0.549 mBq/kg.h, and 4.35 -11.185 mBq/m2.h, respectively, with an mediam of 0.385 mBq/kg.h and 7.691 mBq/m2.h. The effective radium content values range from 28 to 78 mBq/kg with an mediam value of 51.06 mBq/kg, respectively. The concentration of uranium values ranges from 0.334 to 0.858 Bq/kg, with a mean value of 0.602 Bq/kg. The measurements of the radon, radium, and uranium concentration in each sample are significant in terms of health safeguard point of view. Hence, easy, and accurate techniques of analysis are highly demanded.
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Takekawa, Shoichi, Yoshihiko Ueda, Yoshihiko Ueda, Yoshihiro Hiramatsu, Hirotsugu Munechika et Fumio Shishido. « Imaging of Beta-Rays from Tissue Blocks with Thorotrast Deposition by Autoradiography using Fuji Computed Radiography ». Jurnal Radiologi Indonesia 1, no 2 (1 septembre 2015) : 58–64. http://dx.doi.org/10.33748/jradidn.v1i2.7.
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Background: Autoradiography of tissue with radioactive substance such as Thorotrast by Fuji Computed Radiography (FCR) has been available. We obtained autoradiographs from Thorotrast-deposited tissue by FCR. However, the nature of radiation from tissue with Thorotrast was not certain, because alpha particles are shielded by the plastic front of the FCR cassette. Therefore, we undertook investigation to clearly explain the nature of radiation from Thorotrast in case of autoradiography.Materials and Methods: Tissue blocks of liver and spleen with Thorotrast deposition were imaged by autoradiography using FCR, and radioactivity of tissue blocks was measured by a GM survey meter. Measurement was carried out by both with and without an aluminum plate between the tissue and the surface of GM survey meter to shield beta-rays.Results: Autoradiographs of the liver and spleen with Thorotrast were successful. It took only one day to obtain autoradiograph of the spleen, and 14 days for the liver. The radioactivity count decreased dramatically when an aluminum plate was inserted between the specimen and GM survey meter, but some radiation remained. The tissue blocks were contained in a plastic bag and the front of the Cassette of Imaging Plate is covered by a thin plastic board, so alpha-rays from Thorium dioxide in Thorotrast had been shielded from the beginning.Conclusion: We concluded that the radiation from the tissue blocks with Thorotrast in a plastic bag was mostly from beta-rays and less than 5% of radiation was from gamma-rays from the daughter nuclei of Thorium dioxide.
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Shapiro, G. L., S. D. Bulow, K. A. Conklin, L. A. Scheving et G. M. Gray. « Postinsertional processing of sucrase-alpha-dextrinase precursor to authentic subunits : multiple step cleavage by trypsin ». American Journal of Physiology-Gastrointestinal and Liver Physiology 261, no 5 (1 novembre 1991) : G847—G857. http://dx.doi.org/10.1152/ajpgi.1991.261.5.g847.
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Sucrase-alpha-dextrinase, a hybrid digestive carbohydrase of the intestinal brush border, is initially synthesized and transported to the surface membrane as a single-chain glycoprotein, P, which is then cleaved to alpha- and beta-subunits, presumably by one or more pancreatic proteases. However, efforts to convert P under controlled conditions to authentic alpha and beta have been unsuccessful. Sucrase-dextrinase immunoprecipitates from rats intraintestinally labeled with [3H]leucine or [35S]methionine without presence of biliary-pancreatic secretions revealed only the 230-kDa P precursor. Restoration of intestinal flow converted the brush border P to the alpha- (140 kDa) and beta- (125 kDa) subunits. Biliary plus pancreatic secretions facilitated this postinsertional cleavage, but bile alone played no role in conversion. When isolated brush borders, prelabeled in vivo, were exposed to a mixture of pancreatic proteases at physiological concentrations, P was converted to authentic alpha and beta, but only trypsin was responsible for the conversion. Kinetic analysis in prelabeled isolated brush-border vesicles revealed the appearance of several intermediate species (205-145 kDa) produced either by endogenous membrane proteases or by trypsin itself. Reconstituted duodenal luminal contents yielded a fragmentation pattern identical to that produced by trypsin alone. Trypsin was necessary and sufficient for processing of the intermediate precursors to the final authentic alpha- and beta-subunits. Based on the alpha- to beta radioactivity ratio and the known amino acid composition of the subunits, differential cleavage occurred with relatively greater production of the beta-subunit (alpha-to-beta molar ratio = 0.77). The conversion of P to the alpha- and beta-units, rather than occurring in a single step after membrane insertion, is differentially catalyzed by trypsin trimming to unequal amounts of the subunits involving a complex series of cleavage steps.
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Mangset, W., E. Ike, F. Masok, S. Mallam et E. Adetona. « Contour Maps of Gross Alpha and Beta Radioactivity Distribution in Surface Water Supply Within the Naraguta Sheet 168, Plateau State, Nigeria ». Journal of Scientific Research and Reports 8, no 7 (10 janvier 2015) : 1–13. http://dx.doi.org/10.9734/jsrr/2015/18932.
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Knot, EA, E. de Jong, JW ten Cate, AH Iburg, CP Henny, T. Bruin et J. Stibbe. « Purified radiolabeled antithrombin III metabolism in three families with hereditary AT III deficiency : application of a three-compartment model ». Blood 67, no 1 (1 janvier 1986) : 93–98. http://dx.doi.org/10.1182/blood.v67.1.93.93.
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Abstract Purified human radioiodinated antithrombin III (125I-AT III) was used to study its metabolism in six members from three different families with a known hereditary AT III deficiency. Six healthy volunteers served as a control group. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and crossed immunoelectrophoresis (CIE) showed the purified AT III to be homogeneous. Amino acid analysis of the protein revealed a composition identical to a highly purified internal standard. The specific activity was 5.6 U/mg. Analysis of plasma radioactivity data was performed, using a three-compartment model. Neither plasma disappearance half-times nor fractional catabolic rate constants differed significantly between patients and control subjects. The mean absolute catabolic rate in the patient group was significantly lower than that of the control group at 2.57 +/- 0.44 and 4.46 +/- 0.80 mg/kg/day, respectively. In addition, the mean patient alpha 1-phase, flux ratio (k1,2 and k2,1) of the second compartment alpha 2-phase and influx (k3,1) of the third compartment were significantly reduced as compared with control values. It has been tentatively concluded that the observed reduction in the second compartment may be caused by a decrease in endothelial cell surface binding.
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Knot, EA, E. de Jong, JW ten Cate, AH Iburg, CP Henny, T. Bruin et J. Stibbe. « Purified radiolabeled antithrombin III metabolism in three families with hereditary AT III deficiency : application of a three-compartment model ». Blood 67, no 1 (1 janvier 1986) : 93–98. http://dx.doi.org/10.1182/blood.v67.1.93.bloodjournal67193.
Texte intégralRésumé :
Purified human radioiodinated antithrombin III (125I-AT III) was used to study its metabolism in six members from three different families with a known hereditary AT III deficiency. Six healthy volunteers served as a control group. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and crossed immunoelectrophoresis (CIE) showed the purified AT III to be homogeneous. Amino acid analysis of the protein revealed a composition identical to a highly purified internal standard. The specific activity was 5.6 U/mg. Analysis of plasma radioactivity data was performed, using a three-compartment model. Neither plasma disappearance half-times nor fractional catabolic rate constants differed significantly between patients and control subjects. The mean absolute catabolic rate in the patient group was significantly lower than that of the control group at 2.57 +/- 0.44 and 4.46 +/- 0.80 mg/kg/day, respectively. In addition, the mean patient alpha 1-phase, flux ratio (k1,2 and k2,1) of the second compartment alpha 2-phase and influx (k3,1) of the third compartment were significantly reduced as compared with control values. It has been tentatively concluded that the observed reduction in the second compartment may be caused by a decrease in endothelial cell surface binding.
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Olanrewaju, A., E. Osarulobe et G. Avwiri. « Measurements of Gross Alpha and Beta Radioactivity in Surface Soil, Mineral Rock and Consumable Water around Mining Sites in Benue State, Nigeria ». Journal of Scientific Research and Reports 18, no 5 (26 mars 2018) : 1–14. http://dx.doi.org/10.9734/jsrr/2018/39193.
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Mangset, E. W., et P. J. Bulus. « Gross Alpha and Beta Radioactivity in Surface Water and Soil from Lead and Zinc Mining Area and their Radiological Risks in Wase Local Government Area, Plateau State, Nigeria ». INTERNATIONAL JOURNAL OF APPLIED SCIENCE AND MATHEMATICAL THEORY 8, no 2 (19 septembre 2022) : 51–62. http://dx.doi.org/10.56201/ijasmt.v8.no2.2022.pg51.62.
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Radionuclides are naturally found throughout all environments. They are present in varying amounts in air, water, plants animals, soil and water. In this study ten (10) water samples and fifteen (15) soil samples from Zinc and Lead mining areas in Kampani Zurak village, Wase LGA of Plateau state were collected using standard methods. The samples were analyzed for gross alpha and beta activities using MPC – 2000-DP. The results obtained showed that the gross alpha activities in water ranged from (0.005 ± 0.004 – 0.456 ± 0.019) Bq/l with a mean value of 0.1059 ± 0.0087 Bq/l while the gross beta activities for the water samples ranged from (0.290± 0.009- 1.450 ± 0.047) Bq/l with a mean value of 0.723 ± 0.1335Bq/l. The gross alpha activities in soil samples ranged from (0.003± 0.001- 0.737 ± 0.132) Bq/g with a mean value of 0.1876 ± 0.0301 Bq/g and the gross beta activities ranged from (0.003± 0.004- 3.615 ± 0.003) Bq/g with a mean value of 0.3961 ± 0.0099 Bq/g. The committed effected doses for adults ranged from (0.001- 0.092) mSV/yr with a mean value of 0.0216mSV/yr while for children it ranged from (0.001-0.137) mSV/yr with a mean value of 0.0316mSV/yr. The committed effective doses to children and adults were compared with the WHO’s standard limit of 0.1mSv/yr. The results indicated that location 3 had relatively high dose to children while other locations are within the standard limits. From the results obtained, 40% of the water and soil samples analyzed had their activity above the WHO’s Standard Limits. This implies that the general public in the studied areas where their values are above the accepted limit may be exposed to radiation health risks
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Li, Ruth Gong, Kim Lindland, Sandra Karen Tonstad, Tina Bjørnlund Bønsdorff, Asta Juzeniene, Sara Westrøm et Roy Hartvig Larsen. « Improved Formulation of 224Ra-Labeled Calcium Carbonate Microparticles by Surface Layer Encapsulation and Addition of EDTMP ». Pharmaceutics 13, no 5 (29 avril 2021) : 634. http://dx.doi.org/10.3390/pharmaceutics13050634.
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Radium-224-labeled CaCO3 microparticles have been developed to treat peritoneal carcinomatosis. The microparticles function as carriers of 224Ra, facilitating intraperitoneal retention of the alpha-emitting radionuclide. It was necessary to control the size of microparticles in suspension over time and introduce a sterilization process for the clinical use of the radiopharmaceutical. Ethylenediamine tetra(methylene phosphonic acid) (EDTMP) was investigated as a stabilizing additive. The possibility of encapsulating the radiolabeled microparticles with an outer surface layer of CaCO3 for the improved retention of radioactivity by the carrier was studied. This work evaluated these steps of optimization and their effect on radiochemical purity, the biodistribution of radionuclides, and therapeutic efficacy. An EDTMP concentration of >1% (w/w) relative to CaCO3 stabilized the particle size for at least one week. Without EDTMP, the median particle size increased from ~5 µm to ~25 µm immediately after sterilization by autoclaving, and the larger microparticles sedimented rapidly in suspension. The percentage of adsorbed 224Ra progeny 212Pb increased from 56% to 94% at 2.4–2.5% (w/w) EDTMP when the 224Ra-labeled microparticles were layer-encapsulated. The improved formulation also resulted in a suitable biodistribution of radionuclides in mice, as well as a survival benefit for mice with intraperitoneal ovarian or colorectal tumors.
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Silva, L. Sousa, et B. R. S. Pecequilo. « Gross alpha and beta activities in surface, underground and drinking waters of a high natural radioactivity region of central south Bahia state, Brazil ». Radioprotection 46, no 6 (2011) : S63—S67. http://dx.doi.org/10.1051/radiopro/20116630s.
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Nanjo, H., H. Adachi, M. Aketa, T. Mizoguchi, T. Nishihara et T. Terada. « The role of cysteine in the alteration of bovine liver dihydrodiol dehydrogenase 3 activity ». Biochemical Journal 310, no 1 (15 août 1995) : 101–7. http://dx.doi.org/10.1042/bj3100101.
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Bovine liver NADP(+)-dependent dihydrodiol dehydrogenase (DD3) is extremely sensitive to SH reagents such as N-ethylmaleimide (NEM) and 5,5′-dithiobis(2-nitrobenzoic acid). NEM produced time- and concentration-dependent inactivation of DD3 in a pseudo-first-order reaction manner. This inactivation was prevented by NADP+, 3-acetylpyridine-adenine dinucleotide phosphate, 2′,5′-ADP and 2′-AMP but not by substrates, NAD+, nicotinamide mononucleotide or 5′-ADP.DD3 was absorbed by an affinity column of thiopropyl-Sepharose 6B, but enzyme incubated with both NEM and NADP+ was not. Moreover, one [14C]NEM molecule was incorporated into a cysteine of DD3 in the presence, and two cysteines of DD3 in the absence, of NADP+. These results suggested that two cysteine residues were modified per enzyme molecule by NEM, one was protected by NADP+ and the other had no significant function for the enzyme activity. Two radiolabelled peptides (P1 and P2) produced by the digestion with lysyl endopeptidase of [14C]NEM-modified DD3 could be separated by reverse-phase HPLC. P1, which was radiolabelled by [14C]NEM only in the absence of NADP+, showed the following sequence; H2N-Tyr-Lys-Pro-Val-Xaa-Asn-Gln-Val-Glu- NEM.Cys-His-Pro-Tyr-Phe-Asn-Gln-Ser-Lys-COOH (Xaa indicates a possible cysteine residue). This sequence was very similar to that of rat liver 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase (3 alpha-HSD/DD) (residues 184 to 201) and was also highly conserved in the aldo-keto reductase superfamily. The sequence of P2, which had radioactivity in both the absence and presence of NADP+, also contained an NEM-modified cysteine and was similar in sequence to the regions located in loop A of rat 3 alpha-HSD/DD. The present study suggests that P1, which may have a cysteine residue corresponding to Cys-193 of rat 3 alpha-HSD/DD, functions in the alteration of DD3 activity depending on the modulation of NADP(+)-binding ability through a thiol/disulphide exchange reaction similar to that of rat 3 alpha-HSD/DD shown in our previous results; while P2, which may have a cysteine residue corresponding to Cys-145 of rat 3 alpha-HSD/DD, may be located near the surface of the enzyme molecule.
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Leikauf, G. D., S. P. Fink, M. L. Miller, J. E. Lockey et K. E. Driscoll. « Refractory ceramic fibers activate alveolar macrophage eicosanoid and cytokine release ». Journal of Applied Physiology 78, no 1 (1 janvier 1995) : 164–71. http://dx.doi.org/10.1152/jappl.1995.78.1.164.
Texte intégralRésumé :
Refractory ceramic fiber has been developed for industrial processes requiring materials with high thermal and mechanical stability. To evaluate the biological activity of this fiber, rat alveolar macrophages were exposed for < or = 24 h to 0–1,000 micrograms/ml of refractory ceramic fiber, crocidolite asbestos, silica (fibrogenic particles), or titanium dioxide (a nonfibrogenic particle), and eicosanoid, tumor necrosis factor-alpha (TNF), and lactate dehydrogenase release were measured. Particle dimensions were determined by electron microscopy. Radioactivity coeluting with leukotriene B4 (LTB4) and immunoreactive LTB4 and TNF release increased after refractory ceramic fiber and were similar in magnitude after asbestos but less than after silica. For example, the total [3H]eicosanoid release increased 3.9-fold after refractory ceramic fiber, 4.6-fold after asbestos, and 8.7-fold after silica. Refractory ceramic fiber and asbestos also have similar particle dimensions (diameter, length, and surface area). Inasmuch as macrophage-derived LTB4 and TNF are potent mediators in inflammatory events, including migration and activation of neutrophils, these findings suggest that refractory ceramic fiber can activate macrophages in vitro to release mediators relevant to in vivo findings of inflammation and fibrotic lung disease in laboratory animals.
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Kheder, Malik Hussain. « Measurement of Radon Concentration Using SSNTD in Bartella Region ». Al-Mustansiriyah Journal of Science 29, no 4 (6 mai 2019) : 110. http://dx.doi.org/10.23851/mjs.v29i4.357.
Texte intégralRésumé :
The alpha-radioactive inert gas Radon exhalation is associated with presence of Radium and its ultimate precursor uranium in the earth crust. Uranium decay deposits radon in soil, which is harmful on human and environment. The exposure of population to high concentration of alpha radioactivity mainly of Radon for a long period leads to lung cancer. The radon activity concentrations, radium contents, radon exhalation rates in twenty one soil samples collected from Bartella region, were measured using the sealed-can technique based on the CR-39 SSNTDs. In the present paper the estimated values for radon activity concentration in air space are in the range 323.2-2424 Bq/m3 with mean value of 1212.7 Bq/m3, the radon concentration in soil sample are 31.66-237.46 KBq/m3 with mean value of 118.83 KBq/m3, the radium contents were found vary between 1.36-10.24 Bq/Kg with mean value 5.11 Bq/Kg, the radon mass exhalation rate vary between 10.34-77.56 mBq/Kg/hr with mean 38.81 mBq/Kg/hr, the radon surface exhalation rate are between 234.2-1756.4 mBq/m2/hr with mean value of 878.6 mBq/m2/hr. All values of the samples under the test are below of permissible values 370 Bq/Kg of radium content and 57600 mBq/m2/hr radon exhalation, recommended by Organization for Economic Cooperation and Development (OECD). Hence the area under investigation is safe as for as health hazards of radium and safe in radiological risks due to radon exposure from the soil.
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Guagliardi, Ilaria, Tommaso Caloiero, Ernesto Infusino, Giovanni Callegari et Nicola Ricca. « Environmental Estimation of Radiation Equivalent Dose Rates in Soils and Waters of Northern Calabria (Italy) ». Geofluids 2021 (27 avril 2021) : 1–8. http://dx.doi.org/10.1155/2021/6617283.
Texte intégralRésumé :
In this study, the equivalent dose rate of natural radionuclides ( H T ) in 99 spring water and surface soil samples was determined using an alpha, beta, and gamma high sensitivity detector up within a Geiger-Muller tube and with an external probe NaI (Tl). The samples were collected in the Crati basin (southern Italy), and during sample collection, water quality parameters were detected in situ and at the University of Calabria laboratories. A Pearson correlation coefficient analysis was applied to identify and clarify the relationships between water physical-chemical properties and soil and water radioactivity. Results show that the mean H T for spring waters is 97.07 μSv/h. Furthermore, the mean H T for surface soils is 97.92 μSv/h, thus evidencing higher mean H T values than worldwide ones reported in a previous literature. Low correlation coefficients were detected between water H T and conductivity and pH. On the contrary, a reasonable correlation was found between H T in spring water and in soil. This relationship is associated with some rocks of the Sila Massif and of Coastal Chain, i.e., plutonic and metamorphic crystalline rocks. Finally, the estimation of the health risk was calculated: results did not evidence serious dangers for people living in the studied environment. The results from this survey for the H T evaluation provide an extensive assessment of the background exposure levels in the investigated area.
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Wadhwani, K. C., Q. R. Smith et S. I. Rapoport. « Facilitated transport of L-phenylalanine across blood-nerve barrier of rat peripheral nerve ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 258, no 6 (1 juin 1990) : R1436—R1444. http://dx.doi.org/10.1152/ajpregu.1990.258.6.r1436.
Texte intégralRésumé :
L-Phenylalanine transport across the blood-nerve barrier was studied by perfusing Ringer solution containing trace amounts of L-[14C]phenylalanine and [3H]dextran (a vascular marker) through the hindlimb of an anesthetized rat. At the end of perfusion, a segment of sciatic nerve was removed, frozen, desheathed, and processed for radioactivity counting. The permeability-surface area product of the blood-nerve barrier (PABNB) to L-[14C]phenylalanine decreased from 58 +/- 9 X 10(-5) to 1.7 +/- 0.3 X 10(-5) (SE) ml.s-1.g wet wt-1, as the perfusate concentration of unlabeled L-phenylalanine was increased to 10 mM. D-Phenylalanine had less of an inhibitory effect on L-[14C]phenylalanine uptake than did L-phenylalanine. PABNB did not change in the presence of 50 mM alpha-(methylamino)isobutyric acid (MeAIB) in the perfusion medium, nor by replacing NaCl by Tris.HCl. However, addition of 50 mM 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH) reduced PABNB to 2.1 +/- 0.3 X 10(-5) ml.s-1.g wet wt-1 (n = 4). PA at epiperineurial barrier (PAper) of L-[14C]phenylalanine at the epiperineurial barrier, determined from in situ incubation, was 1.4 +/- 0.2 X 10(-5) ml.s-1.g wet wt-1 (n = 6) and was unaffected by 10 mM L-phenylalanine concentration in the incubation medium. The results demonstrate for the first time carrier-mediated transport system for L-phenylalanine at the blood-nerve barrier of the rat peripheral nerve.
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Nawroth, P., D. Handley, G. Matsueda, R. De Waal, H. Gerlach, D. Blohm et D. Stern. « Tumor necrosis factor/cachectin-induced intravascular fibrin formation in meth A fibrosarcomas. » Journal of Experimental Medicine 168, no 2 (1 août 1988) : 637–47. http://dx.doi.org/10.1084/jem.168.2.637.
Texte intégralRésumé :
Recent studies have indicated that TNF can promote activation of the coagulation mechanism by modulating coagulant properties of endothelial cells. In this report, we demonstrate that infusion of low concentrations of TNF (3 micrograms/animal) into mice bearing meth A fibrosarcomas leads to localized fibrin deposition with formation of occlusive intravascular thrombi in close association with the endothelial cell surface. Studies with 125I-fibrinogen showed tenfold enhanced accumulation of radioactivity in tumor within 2 h after TNF infusion. Western blots of tumor extracts subjected to SDS-PAGE and visualized with a fibrin-specific mAb indicated that fibrin forms in the tumor after the TNF infusion. Electron microscopic studies demonstrated fibrin strands, based on the characteristic 21-nm periodicity, which appeared to be adherent to the endothelial cell surface. Further ultrastructural studies indicated that fibrin formation, first evident within 30 min of the TNF infusion, led to occlusive thrombi limited to the tumor vascular bed (i.e., not in the normal mouse vasculature) within 2 h and was associated with an 80% reduction in tumor perfusion based on studies with Evans blue. In view of previous work concerning TNF induction of endothelial cell procoagulant activity, the hypothesis that tumor cell products prime the response of endothelium to this cytokine was tested. Supernatants of cultured meth A fibrosarcomas obtained serum-free conditions, which had no intrinsic procoagulant activity, considerably enhanced tissue factor induction in endothelium in response to submaximal concentrations of TNF. The factor(s) in the tumor-conditioned medium appeared to be distinct from IL-1, fibroblast growth factor, IFN-gamma, TNF, endotoxin, TGF-alpha, and TGF-beta. These studies delineate a novel model of localized clot formation in which thrombosis is initiated by a pathophysiologic mediator, TNF, and provides an opportunity to examine mechanisms in the microenvironment directing clot formation to the tumor vascular bed.
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Miller, Claire E., Jonathan D. Rock, Kristian A. Ridley, Peter H. Williams et Julian M. Ketley. « Utilization of Lactoferrin-Bound and Transferrin-Bound Iron by Campylobacter jejuni ». Journal of Bacteriology 190, no 6 (18 janvier 2008) : 1900–1911. http://dx.doi.org/10.1128/jb.01761-07.
Texte intégralRésumé :
ABSTRACT Campylobacter jejuni NCTC 11168 was capable of growth to levels comparable with FeSO4 in defined iron-limited medium (minimal essential medium alpha [MEMα]) containing ferrilactoferrin, ferritransferrin, or ferri-ovotransferrin. Iron was internalized in a contact-dependent manner, with 94% of cell-associated radioactivity from either 55Fe-loaded transferrin or lactoferrin associated with the soluble cell fraction. Partitioning the iron source away from bacteria significantly decreased cellular growth. Excess cold transferrin or lactoferrin in cultures containing 55Fe-loaded transferrin or lactoferrin resulted in reduced levels of 55Fe uptake. Growth of C. jejuni in the presence of ferri- and an excess of apoprotein reduced overall levels of growth. Following incubation of cells in the presence of ferrilactoferrin, lactoferrin became associated with the cell surface; binding levels were higher after growth under iron limitation. A strain carrying a mutation in the cj0178 gene from the iron uptake system Cj0173c-Cj0178 demonstrated significantly reduced growth promotion in the presence of ferrilactoferrin in MEMα compared to wild type but was not affected in the presence of heme. Moreover, this mutant acquired less 55Fe than wild type when incubated with 55Fe-loaded protein and bound less lactoferrin. Complementation restored the wild-type phenotype when cells were grown with ferrilactoferrin. A mutant in the ABC transporter system permease gene (cj0174c) showed a small but significant growth reduction. The cj0176c-cj0177 intergenic region contains two separate Fur-regulated iron-repressible promoters. This is the first demonstration that C. jejuni is capable of acquiring iron from members of the transferrin protein family, and our data indicate a role for Cj0178 in this process.
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Das, S., A. K. Saha, N. K. Mukhopadhyay et R. H. Glew. « A cyclic nucleotide-independent protein kinase in Leishmania donovani ». Biochemical Journal 240, no 3 (15 décembre 1986) : 641–49. http://dx.doi.org/10.1042/bj2400641.
Texte intégralRésumé :
Leishmania donovani promastigotes labelled for 2 h with 32Pi incorporated radioactivity into at least 21 different proteins, as determined by SDS/polyacrylamide-gel electrophoresis. Pulse-chase studies with 32Pi demonstrated that the labelled proteins were in a dynamic state: some radiolabelled proteins rapidly disappeared and others appeared after the chase. The possibility of an ectokinase on the parasite was examined; incubation of intact parasites for 10 min at 25 degrees C in an osmotically buffered medium containing [gamma-32P]ATP, but not [alpha-32P]ATP, resulted in the labelling of 10 different protozoal proteins, presumably localized to the surface of the organism's plasma membrane. Intact promastigotes also catalysed the transfer of 32P from [gamma-32P]ATP to histones. The histone-dependent kinase was solubilized by repeated freezing and thawing, and sonication, and purified 118-fold by chromatographing the high-speed (200,000 g, 1 h) supernatant fraction on QAE-Sephadex, Sephadex G-150 and hydroxyapatite columns. The kinase eluted as a single activity peak from all three columns. The partially purified histone-dependent kinase had the following properties: pH optimum, 7.0; optimum temperature, 37 degrees C; Km for mixed calf thymus histone, 0.15 mM; Km for ATP, 0.8 mM; preferred fractionated histone acceptors, H2b greater than H4 greater than H2a greater than H3 (H1 does not serve as an acceptor); optimum activity required 10-20 mM-Mg2+; inhibited 50-80% by 0.01 mM- and 1 mM-Ca2+; activity was not stimulated by calmodulin, cyclic AMP (1 mM) or cyclic GMP (1 mM) nor inhibited by a cyclic AMP-dependent protein kinase inhibitor (50 micrograms/assay); apparent Mr 75,000, as determined by Sephadex G-150 gel filtration chromatography; phosphorylated exclusively serine residues. Protein kinase activity was low in the early exponential phase of the growth curve and increased 6-fold upon entry into the stationary phase.
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Niinobu, T., M. Ogawa, A. Murata, J. Nishijima et T. Mori. « Identification and characterization of receptors specific for human pancreatic secretory trypsin inhibitor. » Journal of Experimental Medicine 172, no 4 (1 octobre 1990) : 1133–42. http://dx.doi.org/10.1084/jem.172.4.1133.
Texte intégralRésumé :
Specific binding sites for human pancreatic secretory trypsin inhibitor (PSTI) on 3T3 Swiss albino cells were studied using radioiodinated recombinant PSTI. Some ion species, pH, and temperature significantly influenced the binding of 125I-PSTI. Kinetic studies showed that the binding of 125I-PSTI to 3T3 Swiss albino cells reached the maximum level within 120 min at 4 degrees C, with a slow dissociation rate. The half-maximal inhibition (ID50) of 125I-PSTI binding by unlabeled PSTI occurred at 1.0 x 10(-10) M. On Scatchard analysis of the competitive binding data, linear plots indicated a single class of receptors with high affinity (Kd = 5.3 x 10(-10) M) on 3T3 Swiss albino cells, the number of receptors being 5,400 per cell. Treatment of surface-bound radiolabeled PSTI with a chemical crosslinker (disuccinimidyl suberate) led to the identification of a membrane polypeptide of Mr 140,000 to which PSTI was crosslinked. The formation was inhibited by an excess amount of unlabeled PSTI in a dose-dependent manner. The binding of 125I-PSTI to 3T3 Swiss albino cells was competitively inhibited by unlabeled PSTI but not by other peptide hormones, such as epidermal growth factor (EGF), bovine fibroblast growth factor, insulin-like growth factor, transforming growth factor alpha, platelet-derived growth factor, and tumor necrosis factor, indicating the presence of receptors specific for PSTI. Various protease inhibitors had no or only a little effect, and mercaptoethanol and dithiothreitol strongly decreased the binding of 125I-PSTI. Incubation at 37 degrees C resulted in rapid internalization of cell-bound 125I-PSTI, followed by the appearance of trichloroacetic acid-soluble 125I-radioactivity in the culture medium, due to degradation of internalized PSTI. In addition, PSTI stimulated [3H]thymidine incorporation into DNA on 3T3 Swiss albino cells in a dose-dependent manner. The combined addition of PSTI and EGF stimulated [3H]thymidine incorporation to an extent greater than that seen with either agent alone. These results indicated that the biological effect of PSTI was mediated by high affinity plasma membrane receptors, which were not a cell-surface proteinase(s). Specific binding of 125I-PSTI was noted with the following cells: WI-38, 3T3 Swiss albino, HUVE, BDC-1, and H4-II-E-C3.
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Emproto, Christopher, Austin Alvarez, Christian Anderkin et John Rakovan. « The Crystallinity of Apatite in Contact with Metamict Pyrochlore from the Silver Crater Mine, ON, Canada ». Minerals 10, no 3 (7 mars 2020) : 244. http://dx.doi.org/10.3390/min10030244.
Texte intégralRésumé :
The purpose of this work is to evaluate the long-term effects of radiation on the structure of naturally occurring apatite in the hope of assessing its potential for use as a solid nuclear waste form for actinide sequestration over geologically relevant timescales. When a crystal is exposed to radioactivity from unstable constituent atoms undergoing decay, the crystal’s structure may become damaged. Crystalline materials rendered partially or wholly amorphous in this way are deemed “partially metamict” or “metamict” respectively. Intimate proximity of a non-radioactive mineral to a radioactive one may also cause damage in the former, evident, for example, in pleochroic haloes surrounding zircon inclusions in micas. Radiation damage may be repaired through the process of annealing. Experimental evidence suggests that apatite may anneal during alpha particle bombardment (termed “self-annealing”), which, combined with a low solubility in aqueous fluids and propensity to incorporate actinide elements, makes this mineral a promising phase for nuclear waste storage. Apatite evaluated in this study occurs in a Grenville-aged crustal carbonatite at the Silver Crater Mine in direct contact with U-bearing pyrochlore (var. betafite)—a highly radioactive mineral. Stable isotope analyses of calcite from the carbonatite yield δ18O and δ13C consistent with other similar deposits in the Grenville Province. Although apatite and betafite imaged using cathodoluminescence (CL) show textures indicative of fracture-controlled alteration, Pb isotope analyses of betafite from the Silver Crater Mine reported in previous work are consistent with a model of long term Pb loss from diffusion, suggesting the alteration was not recent. Thus, it is interpreted that these minerals remained juxtaposed with no further metamorphic overprint for ≈1.0 Ga, and therefore provide an ideal opportunity to study the effects of natural, actinide-sourced radiation on the apatite structure over long timescales. Through broad and focused X-ray beam analyses and electron backscatter diffraction (EBSD) mapping, the pyrochlore is shown to be completely metamict—exhibiting no discernible diffraction associated with crystallinity. Meanwhile, apatite evaluated with these methods is confirmed to be highly crystalline with no detectable radiation damage. However, the depth of α-decay damage is not well-understood, with reported depths ranging from tens of microns to just a few nanometers. EBSD, a surface sensitive technique, was therefore used to evaluate the crystallinity of apatite surfaces which had been in direct contact with radioactive pyrochlore, and the entire volume of small apatite crystals whose cores may have received significant radiation doses. The EBSD results demonstrate that apatite remains crystalline, as derived from sharp and correctly-indexed Kikuchi patterns, even on surfaces in direct contact with a highly radioactive source for prolonged periods in natural systems.
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Celada, A., et R. D. Schreiber. « Internalization and degradation of receptor-bound interferon-gamma by murine macrophages. Demonstration of receptor recycling. » Journal of Immunology 139, no 1 (1 juillet 1987) : 147–53. http://dx.doi.org/10.4049/jimmunol.139.1.147.
Texte intégralRésumé :
Abstract Although the interferon-gamma (IFN-gamma) receptor on murine and human mononuclear phagocytes has been defined and partially characterized, very little data exists which describes the ultimate fate of receptor-bound ligand. The current studies were specifically designed to define the metabolic processes which act on murine recombinant IFN-gamma following its interaction with murine macrophages at physiologic temperatures. Ligand internalization was demonstrated by comparing binding of [125I]IFN-gamma to macrophages at 4 degrees C and 37 degrees C. When binding was carried out at 4 degrees C, 96% of the cell-associated [125I]IFN-gamma remained accessible at the plasma membrane and could be stripped from the cell by exposure to pronase. In contrast, at 37 degrees C, only 35% of the cell-associated radioactivity was pronase strippable. Macrophages degraded [125I]IFN-gamma into trichloroacetic acid-soluble material at 37 degrees C at a constant rate of 7000 molecules/cell/hr over a 12-hr time period. The amount of IFN-gamma degraded correlated with the amount of IFN-gamma bound to the cell surface. The receptor was neither up- nor down-regulated by ligand or by other agents known to regulate macrophage functional activity such as IFN-alpha, IFN-beta, lipopolysaccharide, or phorbol myristate acetate. The constant uptake of IFN-gamma by macrophages was due to the presence of an intracellular receptor pool (62% of the total receptor number) and to a mechanism of receptor recycling. Evidence for the latter was obtained using lysosomotropic agents which blocked degradation but not binding and internalization of ligand and caused the intracellular accumulation of receptor. By comparing the relationship between receptor occupancy and biologic response induction, two activation mechanisms became apparent. Induction of certain functions, such as H2O2 secretion, appeared to require only a single round of receptor occupancy. However, induction of more complex functions such as nonspecific tumoricidal activity appeared to require three to four rounds of receptor occupancy. These results thus support the concept that IFN-gamma internalization and receptor recycling are essential in the induction of nonspecific tumoricidal activity by macrophages.
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Staak, Jan O., David Colcher, Jianyi Wang, Andreas Engert et Andrew A. Raubitschek. « Radioimmunotherapy Utilizing the Humanized Anti-CD25 Mab Daclizumab Is Highly Effective in Mice Bearing Human Hodgkin’s Lymphoma Xenografts. » Blood 104, no 11 (16 novembre 2004) : 4632. http://dx.doi.org/10.1182/blood.v104.11.4632.4632.
Texte intégralRésumé :
Abstract Objectives: CD25 is overexpressed on the cell surface by a variety of malignant diseases including Hodgkin’s lymphoma (HL). It is cleaved from the cell surface releasing a soluble ectodomain (sCD25) which may interfere with a radiolabeled MAb’s ability to reach the target cell. Daclizumab (Zenapax®), a humanized IgG1 that binds to the alpha subunit of the human interleukin-2 (IL-2) receptor (CD25, Tac), is FDA-approved for the prophylaxis of renal transplant rejection, as part of an immunosuppressive regimen. We performed biodistribution and γ-imaging studies of 111In-labeled Zenapax and investigated the therapeutic efficacy of the 90Y-labeled version in a human CD25+ human HL xenograft mouse model. Materials & Methods: Zenapax was conjugated to the macrocyclic bifunctional chelate DOTA-NHS active ester. For biodistribution studies athymic nude mice bearing s.c. L540 (human HL line) tumors were injected i.v. with 111In-DOTA-Zenapax or 111In-DOTA-M5A (humanized anti-CEA; 3-5μCi, 2-3μCi/μg) as a control. At various timepoints tumors, blood and major organs were collected, weighed and analyzed for radioactivity. The percent injected dose per gram (%ID/g) was determined. Serum samples were analyzed by HPLC size exclusion chromatography (SEC). For γ-imaging studies L540-tumor-bearing mice received 111In-Zenapax (10.5μCi, 1.8μCi/μg) and serial images were acquired at various timepoints. For the evaluation of therapeutic efficacy, groups of 8 L540 tumor bearing nude mice were injected i.v. with a single dose of 90Y-labeled-Zenapax (0, 40, 60, 80, 100, or 120μCi). Tumor progression was monitored by physical measurements. Results: Maximum tumor accretion for Zenapax was 35 %ID/g at 72h vs. 9 %ID/g for the control MAb. There were no significant differences in normal organ distribution or clearance from the blood between both MAbs. HPLC analysis of serum from Zenapax treated mice showed complexes formation (6–16%; ~210kD), consisting of the MAb and sCD25. γ-imaging studies demonstrated significant tumor retention of 111In-Zenapax. Therapeutic efficacy was dose-dependent with complete tumor regression in all mice receiving 100–120 μCi, as well as 5/8 after 80μCi, and 4/8 after 40–60μCi. No severe toxicities were observed. In animals with regrowth of tumors the average delay was 18, 37, and 41 days for mice treated with 40, 60, and 80μCi, respectively. Untreated mice were sacrificed after 21 days due to excessive tumor progression or tumor ulceration. Conclusions: Radiolabeled Zenapax demonstrated favorable biodistribution properties and excellent tumor localization. It was highly efficacious in the treatment of mice bearing human HL xenografts with complete tumor regression in the two higher dose groups and high response rates at lower doses. In mice with incomplete regression significant delay of tumor progression was observed. 90Y-Zenapax was well tolerated without evidence of toxicity. A clinical therapy trial with 90Y-Zenapax in patients with HL is planned.
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Balakin, V., V. Mashinistov et A. Koveria. « Perspective technology of recycling of radioactive contaminated metal based on its melting ». Nuclear and Radiation Safety, no 2(78) (7 juin 2018) : 43–48. http://dx.doi.org/10.32918/nrs.2018.2(78).07.
Texte intégralRésumé :
Melting of the radioactively contaminated metal converts it as a source of ionizing radiation from a surface distribution of radionuclides into the source with their volume distribution. From the surface of the melted metal gamma radiation of a part of radionuclides is emitted, which are in its scope. Alpha and beta radiation are absorbed completely in the metal.
To obtain a radiation-safe metal it is necessary that the amount of gamma-emitting radionuclides, which are loaded into the furnace together with the charge, did not exceed the established allowable level.
The radiation safety criterion of the melted metal is the maximum value of the gamma radiation power from its surface, the established limit of the individual annual effective radiation dose is not exceeded.
There is a need for experimental verification of theoretical results was obtained. The use of this technology will allow the return to industrial production of large amounts of accumulated radioactively contaminated metal and creates conditions for the prevention of environmental violations.
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Kerst, Thomas, Rikard Malmbeck, Nidhu Banik et Juha Toivonen. « Alpha Radiation-Induced Luminescence by Am-241 in Aqueous Nitric Acid Solution ». Sensors 19, no 7 (2 avril 2019) : 1602. http://dx.doi.org/10.3390/s19071602.
Texte intégralRésumé :
When exposed to air, alpha particles cause the production of light by exciting the molecules surrounding them. This light, the radioluminescence, is indicative of the presence of alpha radiation, thus allowing for the optical sensing of alpha radiation from distances larger than the few centimeters an alpha particle can travel in air. While the mechanics of radioluminescence in air and other gas compositions is relatively well understood, the same cannot be said about the radioluminescence properties of liquids. Better understanding of the radioluminescence properties of liquids is essential to design methods for the detection of radioactively contaminated liquids by optical means. In this article, we provide radioluminescence images of Am-241 dissolved in aqueous nitric acid ( HNO 3 ) solution and present the recorded radioluminescence spectrum with a maximum between 350 nm and 400 nm , and a steep decrease at the short wavelength side of the maximum. The shape of the spectrum resembles a luminescence process rather than Cerenkov light, bremsstrahlung, or other mechanisms with broadband emission. We show that the amount of light produced is about 150 times smaller compared to that of the same amount of Am-241 in air. The light production in the liquid is evenly distributed throughout the sample volume with a slight increase on the surface of the liquid. The radioluminescence intensity is shown to scale linearly with the Am-241 concentration and not be affected by the HNO 3 concentration.
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Gilbert, A., J. P. Paccaud et J. L. Carpentier. « Direct measurement of clathrin-coated vesicle formation using a cell-free assay ». Journal of Cell Science 110, no 24 (15 décembre 1997) : 3105–15. http://dx.doi.org/10.1242/jcs.110.24.3105.
Texte intégralRésumé :
Factors controlling the last stages of clathrin-coated vesicle formation were investigated using an assay allowing direct measurement of the detachment of these vesicles from the plasma membrane. Plasma membranes from cultured cells surface-labelled with 125I-alpha2-macroglobulin (a ligand that preferentially associates with clathrin-coated pits) were isolated by sonication of cells attached to a poly-L-lysine-coated substratum and incubated in the presence of nucleotide(s) +/− cytosol. A significant proportion of the membrane-associated radioactivity was released into the incubation medium in sedimentable form (14x10(6)g). The nucleotide and ligand specificities of this process together with the results of a series of biochemical, morphological and gradient analyses, led to the conclusion that measurement of the released sedimentable radioactivity provides a direct estimate of the formation of clathrin-coated vesicles from clathrin-coated pits. A morphological analysis of quick-frozen replicas of these membranes indicated that only the last stages of clathrin-coated vesicle formation were studied in the assay. Taking advantage of this cell-free system, we demonstrate that membrane-associated cytosolic factors and GTP-binding proteins, noteably dynamin, play a crucial role. Moreover, although these events can occur in the absence of ATP and Ca2+, optimal conditions for the formation of clathrin-coated vesicles require the presence of ATP, GTP and cytosol.
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Dudar, T., A. Iakymenko, O. Titarenko et M. Svideniuk. « About Total Alpha Activity of Underground Water Sources ». Nuclear and Radiation Safety, no 1(85) (13 mars 2020) : 63–72. http://dx.doi.org/10.32918/nrs.2020.1(85).07.
Texte intégralRésumé :
Artesian wells remain strategically important sources of drinking water for the Kyiv megacity, especially in the vicinity of radioactively contaminated areas of the Chornobyl exclusion zone. The contribution of groundwater to the total volume of drinking water was indicated. The water from 144 artesian wells was investigated in terms of total alpha activity: 67 of them were drilled up to the Cenomanian aquifer of the Upper Cretaceous, 77 - up to the Bajocian aquifer of the Middle Jurassic.
Studies have found that the total alpha activity in 39 wells exceeds the regulatory limit, with 37 of the 39 wells supplying water from the Bajocian aquifer. The average total alpha activity of the Cenomanian water is 0.033 ± 0.003 Bq/dm3, the most active water of this aquifer is produced in the Obolon area where the average value equals 0.045 ± 0.004 Bq/dm3. The average total alpha activity of the Bajocian water is 0.115 ± 0.012 Bq/dm3, the most active water of this aquifer is produced in the Obolon and Troyeshchyna areas where the average values equal 0.097 ± 0.010 Bq/dm3 and 0.188 ± 0.018 Bq/dm3, respectively. Therefore, in average, the Bajoian water is 3.5 times more active than the Cenomanian one: the average activity reaches 0.115 ± 0.012 Bq/dm3 against 0.033 ± 0.003 Bq/dm3.
GIS mapping of the total content of α-emitters in the groundwater of both aquifers was created. The dynamics of the gross alpha activity of artesian water from both aquifers was monitored for the Obolon area. It was determined that when consuming the Bajocian water, two times more alpha-emitters enter the human body than from the Cenomanian water.
The processing of the results through the spline interpolation with the Spatial Analyst Tools module ArcGIS 10.1 made it possible to analyze this trend for the megacity area: geological and tectonic factors such as block movement of the foundation, unequal incision of ancient watercourses into the pre-Bajocian surface and the erosion of sediments had always had the greatest influence on the enhanced alpha activity of the Bajocian water.
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Nguyen, Van Dung, Thi Lan Anh Vu, Dinh Huan Trinh et Thi Cuc Nguyen. « Radon concentrations and forecasting exposure risks to residents and workers in rare earth and copper mines containing radioactivity in northwest Vietnam ». Ministry of Science and Technology, Vietnam 64, no 1 (15 mars 2022) : 78–84. http://dx.doi.org/10.31276/vjste.64(1).78-84.
Texte intégralRésumé :
Radon and its isotopes are inert gases as they do not interact with any chemical compounds. Compared with thoron (220Rn) and radon-219 (219Rn), the risk of radioactive exposure of radon-222 (222Rn) is very high due to its long half-life of 3.8 d, while the half-life of 220Rn is 55 sec and of 219Rn is 4 sec. As a gas, radon can escape from the surfaces of ore, minerals, and rocks, then dissolve into groundwater and move very far from the formation site. While all these radioisotopes emit alpha radiation, Rn-222 is the most important as it is the main factor behind dangerous doses to the respiratory tract that are harmful to human health. Survey results of radon concentration in the air and retrospective data (from 2017 to 2019) on the health of residents and workers near and in the rare earth mines Dong Pao and Muong Hum, as well as the Sin Quyen copper mine, illustrated the health characteristics of the people involved in the northwestern mineral mines (Lao Cai - Lai Chau) that are exposed to radon. At the Dong Pao and Muong Hum rare earth mines, as well as the Sin Quyen copper mine, residents and workers were exposed to high concentrations of radon gas and thus developed some related illnesses such as respiratory, urological, digestive, genetic, and neurological diseases. Assessing the risk of pulmonary tuberculosis and estimating the average death rate from lung cancer with radon exposure shows that, in the surveyed area, the risk value is high (0.046) compared to other regions of Vietnam. However, it is within the limits allowed by the United States Environmental Protection Agency (EPA).
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Poliakova, I. « RADON AS ONE OF THE MOST DANGEROUS FACTORS AFFECTING MINERS ». Bulletin of Lviv State University of Life Safety, no 18 (31 décembre 2018) : 132–38. http://dx.doi.org/10.32447/20784643.18.2018.15.
Texte intégralRésumé :
Introduction. Ukraine is among the leading mineral and raw material states. Nowadays in Ukraine prospected 20000 deposits and manifestations of 111 kinds of minerals (according to UNIAN - 200 minerals, 120 of which are used by mankind today). Of these 7807 deposits of 94 minerals with industrial value and accounted State balance of stocks. The greatest economic importance are coal, oil and gas, iron ore and manganese, native sulfur, rock and potassium salts, non-metallic building materials, mineral waters. These deposits are located in different geological regions of Ukraine.
During the extraction of natural resources are exposure of personnel of mines and population from naturally occurring radioactive materials (NORM - nature occurring radioactive materials). Adequate levels of radiation safety and radiation protection of the population and the personnel of any branch determined, above all, of the relevant public, industry and other regulations and systems monitoring their implementation. One of the significant components of the increase of radiation safety are methodical application of appropriate radiation monitoring devices and obtaining reliable data (results), which will allow processing to estimate actual radiation situation at the facility.
The natural and climatic conditions of the mines are specific. This fact is confirmed by the level of humidity, which can reach the value of 99%, but the temperature and atmospheric pressure are unchanged. In the process of work in the mine there is a harmful factor for the human body - dust in the air of the working zone and radioactivity. Alpha particles formed as a result of the decomposition of the daughter products of the decay of 224Ra, 223Ra and 226Ra, settling on aerosols and enter the human body by inhalation, as well as actinon, radon and thoron lead to an increase in the dose of personnel.
Purpose. The purpose of the study is to determine the radiation situation at the sites for the extraction of minerals, taking into account the factors that affect the reliability of the results. Establishing reliable quantitative characteristics of harmful factors of the environment, which negatively affects the body of the personnel. Conducting an analysis of existing methods of measuring by direct methods and making suggestions for their improvement under the influence of factors that contribute to obtaining results with an error of more than 75%.
Methods. In the course of the research, direct measurement methods, calculations and analytical research were used to achieve the set goal and to solve the set tasks. During experimental and analytical work of physico-chemical and radiometric measurement methods were used, certified equipment and measuring control devices were used.
Results. Measurements of equilibrium volume activity of radon and thoron using direct method is necessary task to assess the impact on personnel at the work time.
Quantitative assessment the air gases such as 222Rn, 220Rn, 219Rn depends on the amount of deposits of the uranium and thorium series in the earth's surface.
It should not be forgotten that after the radioactive decay of the aforementioned gases, a significant amount of α-radioactive daughter nuclides that enter the miners' body is formed. This causes an increase in the dose from the accumulation of α-radionuclides in the miners' organism, but this staff is not officially considered which works with NORM (with the exception of only uranium miners).
Comparing the results obtained by measuring 222Rn and 220Rn provided in Tables 1 and 2 using direct measurement methods using RHA-2006 «ICAR» and AlphaGuard PQ2000, show difference in the results, especially at higher humidity and with increasing of numbers of mineral dust in the air of mines.
Conclusions. The conclusions obtained by the author of the article on the state of experimental research and analysis of data:
Climatic conditions play an important role in data reliability. It is necessary to carefully select the devices of radiation control and measurement methods.
Conduct a quantitative analysis of radionuclides and set a dose for miners only from radon and thoron, which is possible with the use of a-spectrometry. In this study, an express control (real-time control) of α-emitting radionuclides in the air was carried out using detectors, whose activities are based on the use of an ionization chamber. But as a result of this study, we obtain the total activity of α-radionuclides in the air and α-aerosols identified with a significant systematic error. Since the measuring capabilities of these devices are determined by the humidity of no more than 85%.
The creation of new normative documents to determine the impact on employees and the population of the NORM should be a consequence and an integral part of scientific research in this field. The authenticity of experimental methods and the reliability of the results are the basis upon which radiation safety will be based on working with natural radionuclides.
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Audu, M. U., G. O. Avwiri et C. P. Ononugbo. « Gross Alpha and Gross Beta Radioactivity in Drinkable Water and Soil/Sediment around Oil Spill Sites in Delta State, Nigeria ». Asian Journal of Physical and Chemical Sciences, 19 novembre 2019, 1–12. http://dx.doi.org/10.9734/ajopacs/2019/v7i430100.
Texte intégralRésumé :
The gross alpha and beta activity concentration in drinkable water and soil/sediment from oil spilled communities of Delta state have been carried out using calibrated MPC 2000 Protean ORTEC desktop gross alpha/beta counter. A total of 22 water samples (11 River water and 11 well water) and 22 soil/sediment (11 soil and 11 sediment) were collected in 2-litre plastic containers with about 1% air space left for thermal expansion and black polyethene bags respectively. All the samples were prepared following international standard organization (ISO) procedure. The result showed that gross alpha activity in River water ranged from 0.013±0.005 to 0.0783±0.015 Bql-1 while the gross beta activity concentration in River water ranged from 0.0073±0.015 to 0.0928 ±0.024 Bql-1. The gross alpha and beta activity in ground (well) water ranged from 0.018±0.006 to 0.0817±0.014 Bql-1 and 0.0126 ±0.013 to 0.173±0.063 Bql-1 respectively. The mean gross alpha and beta activity in soil and sediment are 12.0±1.0 and 23.27±3.0 Bq/kg and 23.0±4.0 and 21.73± 15.0 Bq/kg respectively. The total annual effective dose estimated from both alpha and beta emitting radionuclides in water resources sampled, ranged between 0.007 to 0.063 mSvy-1 in river water and 0.021 to 0.102 mSvy-1 for well water. The annual gonadal dose resulting from gross alpha and beta activity in surface and ground water ranges from 0.019 to 0.238 mSvy-1 and 0.037 to 0.406 mSvy-1 respectively. The highest gonad dose of 0.238 mSvy-1 and 0.439 mSvy-1 was obtained in surface water (OTU1) and ground water (OTU2) respectively. The estimated excess lifetime cancer risks range from 0.024 x 10-3 to 0.220 x 10-3 and 0.039 x 10-3 to 0.358 x 10-3 for river and well water respectively. The result showed a significant relationship in both surface and ground water with regression values of 0.66 and 0.84 respectively. This implies that the same radionuclide is responsible for both alpha and beta activities in the water studied. The result of this study show that all the water resources sampled pose no immediate health risk to the populace though, there is little radioactive contamination of the sampled water arising from oil spillages and may be effluent discharge into the surface water. Following no threshold model, the water sampled need to be treated to remove the radionuclide in it through ion exchange technology or reverse osmosis technology before consuming to avoid long term internal exposure.
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Akudo, E. O., E. U. Aniwetalu, A. I. Obasi et K. O. Musa. « Gross alpha and beta radioactivity in surface water and groundwater in Kaduna metropolis, Kaduna State, Nigeria ». International Journal of Energy and Water Resources, 29 octobre 2021. http://dx.doi.org/10.1007/s42108-021-00154-0.
Texte intégral
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Pérez-Reyes, Victoria, Rocío Magaly Cabral-Lares, Carmen Grisel Méndez-García, Carmen del Rocío Caraveo-Castro, Ignacio Alfonso Reyes-Cortés, Jorge Carrillo-Flores et María Elena Montero-Cabrera. « Transport and concentration of uranium isotopes in the Laguna del Cuervo, Chihuahua, Mexico ». Suplemento de la Revista Mexicana de Física 3, no 1 (24 juin 2022). http://dx.doi.org/10.31349/suplrevmexfis.3.010606.
Texte intégralRésumé :
In Chihuahua, an important source of environmental radioactivity is found in the Sierra Peña Blanca, in the center of the state. The site comprises about 70% of uranium reserves in Mexico. The uranium of Peña Blanca was explored and partially exploited in the '80s. Due to the closure of operations, the extracted and unprocessed ore (hundreds of tons) was confined to rocky stacks, exposed to weathering. Subject to leaching, this uranium is transported from the mountains to Laguna del Cuervo. The mineral exposed in the repository and the uranium transport by surface water and recent sediments must be studied, to assess the effects on the environment, with radiometric and materials science techniques in conventional laboratories and synchrotron light. This work presents the study of sediment and pore water samples at various points along the lagoon, and the values of the activity ratio of the 234U/238U isotopes and the sediment-water distribution coefficient of these isotopes, obtained by applying uranium liquid scintillation alpha spectrometry, gamma-ray spectrometry, scanning electron microscopy and X-ray diffraction methods.
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Salaheldin, Ghada, Mervat Elhaddad et Essam Sidique. « Radon concentration and exhalation rate for granitic rocks, Central Eastern Desert, Egypt ». Arabian Journal of Geosciences 15, no 13 (29 juin 2022). http://dx.doi.org/10.1007/s12517-022-09693-0.
Texte intégralRésumé :
Abstract The present work deals with radon pollution arising from granitic rocks using an Alpha Guard radon monitor. Forty-four granitic samples were collected from five sites located in the Central part of the Eastern Desert of Egypt. The minimum to maximum concentration of radon for the rocks of Gebel (mountain) El-Missikat MS, El-Gidamy GD, RieEl-Garra RG, El-Aradiya AR, and Kab-Amira KA were 49,597 ± 8773 to 236,029 ± 22,397 Bq m−3, 39,658 ± 8341 to 188,666 ± 20,545 Bq m−3, 39,854 ± 7645 to 91,393 ± 13,429 Bq m−3, 45,951 ± 9488 to 121,935 ± 14,869 Bq m−3, and 33,209 ± 6989 to 251,398 ± 25,759 Bq m−3, respectively. The surface and mass exhalation rates, the emanation coefficient, and annual effective dose (indoors) were calculated for all the studied samples. The average value of radon concentration in the collected samples was higher than the national reference level of 300 Bq m−3 recommended by ICRP corresponding to an annual effective dose of 4 mSv at work and 14 mSv at home. The measured values for the rock samples studied in the five sites surpassed the world average of soil in areas with normal levels of radioactivity. The MS granitic samples showed a potential radiological risk for human beings, therefore, it is important to carry out a detailed monitoring program for dose assessment.