Search

The Ion-Sensitive Field-Effect Transistor (ISFET) is one of the most popular pH sensors traditionally using to measure hydrogen ion concentration (pH) of the electrolytic solutions. It is developed from Metal Oxide Semiconductor Field-Effect Transistor (MOSFET) by replacing gate electrode with an electrolytic solution to be tested, and a reference metal electrode immersed in that solution. Basic principle of ISFET operation is based on that of standard NMOS structure in conjunction with the insulator-electrolyte capacitor as described in this paper. The site-binding theory (generalized to two kinds of binding sites), together with the Gouy-Chapman-Stern model for the potential profile in the electrolyte, is coupled to the MOS physics. As a result, an approximate analytical model which completely describes static behavior of the ISFET is obtained. The developed description can serve as useful tool for understanding many contemporary biosensors based on original ISFET structure which has broad application in bio-medicine, biological, chemistry and environmental areas.

This study investigates the beryllium-7, lead-210 and caesium-137 activity concentrations in aerosol filter samples collected monthly along the 45°N zonal belt over 1991–2019. Sampling was performed in three locations, one in Serbia and two in Slovenia, and the Slovenian data records are published here for the first time. The activity concentrations were determined by standard gamma spectrometry. The obtained results are in general agreement with the literature data for Europe. The data sets at different sites display similarities in measurement ranges, overall means and seasonal cycles. Still, statistical tests show significant differences among the radionuclides’ concentrations across the locations. To investigate underlying processes that affect radioactivity in the surface air in this region, multivariate statistical concepts are applied to the radionuclides’ concentrations and local meteorological parameters. Discriminant analysis shows that all three sites are well separated from each other. Principal component analysis gives common pattern of interconnection between the observables: temperature has a stronger influence on the behaviour of beryllium-7 and lead-210 than that of caesium-137, but a negative correlation of the radionuclides’ concentrations with precipitation seems the strongest for caesium-137. Principal component analysis also shows local differences in the degree of relationship between the meteorological parameters and activity concentrations of the investigated radionuclides. This is an important finding for future atmospheric transport studies.

Today radioactivity monitoring in the environment is required not only around sites where the significant amounts of radioactive material are used or stored, but in a number of other processes as land remediation or decommissioning of nuclear plants. Since the end of the 20th century there has been an increasing awareness of the so-called technologically enhanced natural radioactivity and the need for its monitoring in a wide range of nonnuclear industries including oil and gas extraction, ceramic and glass industries, production of phosphoric acid, production of different phosphoric fertilizers and other chemical industries. Coal electric power plants as significant sources of ashes and other contaminants are included, too. Contrary to nuclear facilities or radioactive waste control these processes require measuring radionuclides at very low levels of radioactivity. This demands specific methodology and instrumentation and responding to the very real economic importance of classifying waste products from decommissioning and remediation processes. However, natural or man made, waste or industrial, environmental radioactivity monitoring requires adequate equipment calibrated in the full range of radionuclides likely to be encountered, as well as trained and experienced personnel. It is the task of national metrological institutions to provide radioactive reference materials and standards for calibration as pure isotopes, mixtures of isotopes or reference materials for particular applications and to supervise the processes of quality control and quality assurance. Besides primary standards and reference materials national metrological institutions should provide laboratory proficiency testing exercises to support radioactivity measurements within academic, industrial or research laboratories (Spasic, 1984; Spasic, 1985; Spasic, 1987a; Spasic et al. 1987).

This review paper discusses the content of natural ( 40K, 238U, 226Ra, and 232Th) and artificial (137Cs) radionuclides in the soil of the mountains of Maljen, Tara and Kopaonik in the Republic of Serbia over 2002-2015. In addition, the paper gives radiation hazard parameters, i.e., radium equivalent activity, absorbed dose rate, annual effective dose equivalent, external hazard index, annual gonadal dose equivalent, and excess lifetime cancer risk outdoors that we calculated from the obtained content of the natural radionuclides in the soil samples. We compared the parameters to previously published results for different parts of the country and looked into the radioecological status of the investigated areas. U radu su prikazani rezultati gamaspektrometrijskog određivanja sadržaja prirodnih (40K, 238U, 226Ra i 232Th) i proizvedenog (137Cs) radionuklida u zemljištu sa područja planina Maljen, Tara i Kopaonik. Uzorci zemljišta prikupljeni su u periodu od 2002. do 2015. godine na različitim nadmorskim visinama. Na osnovu sadržaja radionuklida u zemljištu odredili smo parametre radijacionog rizika: radijum ekvivalentnu aktivnost, jačinu doze, godišnju efektivnu dozu spoljašnjeg zračenja, indeks spoljašnjeg hazarda, godišnju gonadnu dozu i faktor rizika pojave kancera na području planinskih regiona Republike Srbije, i potom ih uporedili sa ranije objavljenim rezultatima za pojedine regione Republike Srbije.

International audience; Traces of particulate radioactive iodine (131I) were detected in the European atmosphere in January/February 2017. Concentrations of this nuclear fission product were very low, ranging 0.1 to 10 μBq m-3 except at one location in western Russia where they reached up to several mBq m-3. Detections have been reported continuously over an 8-week period by about 30 monitoring stations. We examine possible emission source apportionments and rank them considering their expected contribution in terms of orders of magnitude from typical routine releases: radiopharmaceutical production units > sewage sludge incinerators > nuclear power plants > spontaneous fission of uranium in soil. Inverse modeling simulations indicate that the widespread detections of 131I resulted from the combination of multiple source releases. Among them, those from radiopharmaceutical production units remain the most likely. One of them is located in Western Russia and its estimated source term complies with authorized limits. Other existing sources related to 131I use (medical purposes or sewage sludge incineration) can explain detections on a rather local scale. As an enhancing factor, the prevailing wintertime meteorological situations marked by strong temperature inversions led to poor dispersion conditions that resulted in higher concentrations exceeding usual detection limits in use within the informal Ring of Five (Ro5) monitoring network. © 2018 American Chemical Society.

Kaolins are used in a multiplicity of industries because of unique physical and chemical properties. Relationships between thermal and radioactivity properties are discussed in its application as a building material. Super-fine kaolin powder with particle sizes about 30 mu m was analyzed. Simultaneous TGA/DTA analysis was performed on powder samples at various heating rates in an argon atmosphere. Based on investigated thermal properties, it was concluded that dehydroxylation process can vary depending on the characteristics of starting material. The maximum degree of the dehydroxylation (D (T)) was obtained at the lowest rate of heating (D (T) = 60.79% for 10 A degrees C min(-1)). With an increase in the heating rate, decline in D (T) value was observed. Based on comprehensive testing, it was identified that the degree of dehydroxylation does not drop below 50%. It was concluded that appointed experimental conditions seem sufficient admissible for obtaining degree of dehydroxylation (D (T)) higher than 50%. In order to safe use of kaolin as a building material from the standpoint of radiological safety, content of natural radionuclides was determined by gamma spectrometry.

Significance A massive atmospheric release of radioactive 106Ru occurred in Eurasia in 2017, which must have been caused by a sizeable, yet undeclared nuclear accident. This work presents the most compelling monitoring dataset of this release, comprising 1,100 atmospheric and 200 deposition data points from the Eurasian region. The data suggest a release from a nuclear reprocessing facility located in the Southern Urals, possibly from the Mayak nuclear complex. A release from a crashed satellite as well as a release on Romanian territory (despite high activity concentrations) can be excluded. The model age of the radioruthenium supports the hypothesis that fuel was reprocessed ≤2 years after discharge, possibly for the production of a high-specific activity 144Ce source for a neutrino experiment in Italy., In October 2017, most European countries reported unique atmospheric detections of aerosol-bound radioruthenium (106Ru). The range of concentrations varied from some tenths of µBq·m−3 to more than 150 mBq·m−3. The widespread detection at such considerable (yet innocuous) levels suggested a considerable release. To compare activity reports of airborne 106Ru with different sampling periods, concentrations were reconstructed based on the most probable plume presence duration at each location. Based on airborne concentration spreading and chemical considerations, it is possible to assume that the release occurred in the Southern Urals region (Russian Federation). The 106Ru age was estimated to be about 2 years. It exhibited highly soluble and less soluble fractions in aqueous media, high radiopurity (lack of concomitant radionuclides), and volatility between 700 and 1,000 °C, thus suggesting a release at an advanced stage in the reprocessing of nuclear fuel. The amount and isotopic characteristics of the radioruthenium release may indicate a context with the production of a large 144Ce source for a neutrino experiment.

The gamma spectrometry of environmental samples poses a series of specific problems for the practitioner. The determination of full energy peak efficiencies is, in the case of environmental samples, one of the greatest challenges. In this paper, the calibration of two HPGe detectors for environmental samples in Marinelli beakers was performed using the newly developed MEFFTRAN software. The results obtained with MEFFTRAN were compared to the experimental efficiencies measured using the calibration sample produced at the Laboratory for Radiation and Environment Protection, Institute for Nuclear Sciences Vinca, Belgrade, in order to confirm the validity of the calculation. It is shown that calculated and experimental efficiencies are in good agreement with the discrepancies from -3.9% to +1.5%. The results were also validated by measuring secondary reference materials provided by the IAEA within several interlaboratory proficiency tests. The activity concentration of the radionuclides in the secondary reference materials was determined using the efficiency obtained by MEFFTRAN and compared with the target value given by the IAEA. All the results in materials provided by the IAEA were acceptable except one, proving, that MEFFTRAN produces satisfactory results. (C) 2016 Elsevier Ltd. All rights reserved.

This work presents the results of an investigation undertaken to determine the level of natural radioactivity in the traditional building materials used for medieval indoor vaulted constructions in the territory of the central Balkan region. Indoor radiation exposure varies appreciably if it comes from the earth building materials, hence the presence of natural radioisotopes of 226Ra, 232Th, and 40K in masonry vaulted constructions was analyzed using gamma ray spectrometry. In addition, the internal health hazard index, the absorbed dose rates and the effective annual doses were calculated. The results were then compared both with the reported data from the previous studies concerning the territory of the Balkan Peninsula, as well as with the worldwide values for the materials of historic buildings. The results obtained from the materials examined in this paper all showed the radioactivity levels below the maximum permitted values. [Projekat Ministarstva nauke Republike Srbije, br. 171007 i br. 43009]

This study of environmental radioactivity was carried out in the soils of an urban area. Naturally occurring gamma-emitting radionuclides and man-made Cs-137 were found in the soil profiles collected from four parks in the central Belgrade city area and the soil layer was examined every 10 cm and to a depth of 50 cm. Radioisotope activity concentrations (Bq kg(-1)) in the samples of urban soil using the gamma-ray spectrometry method were in the range of 14-46 for U-238, 33-50 for Ra-226, 29-63 for Pb-210, 1.2-3.4 for U-235, 28-50 for Th-232, 424-576 for K-40 and 0.7-35.8 for Cs-137. Some of the basic physicochemical soil properties (pH, organic matter content, calcium-carbonate content, particle size distribution) were determined to investigate the impact on the vertical distribution of radionuclides. The results of this investigation showed that variations of activity concentration ratios of radionuclides that belong to the same (U-238/Ra-226) or different radioactive series (Th-232/Ra-226; U-235/U-238), including Pb-210/Cs-137 ratios could well be explained by the properties of the soil. Alkaline pH reaction, the accumulation of organic matter in the uppermost and of carbonates in the deepest layers of urban soil had an effect on U-238/Ra-226, and Pb-210/Cs-137 activity concentration ratio values, while Th-232/Ra-226 and partially U-235/U-238 ratios were associated with the particle sizes vertical distribution. A study of radionuclides in the samples of leaves of two deciduous tree species common for these parks was also conducted and Pb-210 and K-40 were found concentrated in leaves rather than other investigated radionuclides.

One of the main problems in quantitative gamma-ray spectroscopy is the determination of detection efficiency, for different energies, source-detector geometries, and composition of samples or sources. There are, in principle, three approaches to this issue: experimental, numerical, and semiempirical. Semiempirical approach is based on the calculation of the efficiency for the measured sample on the basis of an experimental efficiency measured on the same detector, but with a calibration source that can be of different size, geometry, density, or composition—the so-called efficiency transfer. The aim of this paper is to analyze the semiempirical approach, using EFFTRAN and MEFFTRAN software as a typical example. These software were used in the Department of Radiation and Environmental Protection, Vinča Institute of Nuclear Sciences, on three HPGe detectors. The results were compared to the experimentally obtained efficiency, and further validation is performed by measuring reference materials issued within the framework of several interlaboratory intercomparisons. The analysis of the results showed that the efficiency transfer produces good results with the discrepancies within the limits of the measurement uncertainty. Also, for intercomparison measurement, utest criterion for the trueness of the result was applied showing that the majority of the obtained results were acceptable. Some difficulties were identified, and the ways to overcome them were discussed.

This paper presents a study of the profile distribution of available micronutrients Fe, Mn, Cu and Zn and radionuclide 137Cs in cultivated soil at the experimental field 'Radmilovac' (property of Agricultural Faculty, Belgrade University) in the vicinity of Vinča Institute of Nuclear Sciences. The soil belongs to the anthrosol class of anthropogenic soils according to FAO (2006). At first, the deep plowing was performed while preparing soil for planting peach trees followed by cultivation of soil for 12 years. All agricultural treatments at the experimental field ceased for three years. After that period, soil sampling was carried out. Contents of DTPA-extracted Fe, Mn, Cu and Zn were in the range of (mg kg-1): 5.8-41.6; 9.2-34.2; 1-7.6 and 0.2-1.3, respectively. Detected activity concentration (Bq kg-1) for 137Cs ranged from 1.8 to 35. It was noticed that distribution patterns of 137Cs radionuclide and available Cu and Zn along soil depth were very similar and they were analyzed by simple linear regression; mutual affinity for the soil organic matter might affect their distribution in soil. Contents of available Fe and Mn exhibited different, more constant distribution within a soil horizon. U ovom radu ispitivana je raspodela sadržaja pristupačnih mikroelemenata Fe, Mn, Cu i Zn i koncentracije aktivnosti proizvedenog radionuklida 137Cs u profilima zemljišta (dubine 080 cm) sakupljenih sa voćnjaka pod zasadom breskvi na oglednom školskom poljoprivrednom dobru 'Radmilovac' (Poljoprivredni fakultet, Univerzitet u Beogradu) u neposrednoj blizini Instituta za nuklearne nauke 'Vinča'. Zemljište pripada klasi antrosol antropogenih zemljišta prema međunarodnoj FAO (2006) klasifikaciji. Priprema zemljišta za sadnju bresaka izvršena je rigolovanjem, posle čega je usledila 12 godina duga nega voćnjaka. Uzorkovanje zemljišta izvršeno je tri godine nakon prestanka svih poljoprivrednih tretmana zemljišta na oglednom polju. Sadržaji pristupačnih mikroelemenata Fe, Mn, Cu i Zn (dobijeni ekstrakcijom sa rastvorom 0,005 M DTPA) nalazili su se u opsegu (mg kg-1): 5,841,6; 9,234,2; 17,6 odnosno 0,21,3. Detektovana koncentracija aktivnosti 137Cs u zemljištu (merena metodom gama-spektrometrije korišćenjem koaksijalnog HPGe-detektora) nalazila se u intervalu (Bq kg-1): 1,835. Uočeno je da su obrasci distribucije po dubini profila pristupačnih oblika Cu i Zn i radionuklida 137Cs bili veoma slični, a rezultati proste linearne regresione analize su pokazali da je uzajamni afinitet prema organskoj materiji zemljišta mogao da utiče na takvu njihovu distribuciju. Sadržaji pristupačnih mikroelemenata Fe i Mn, pokazali su da imaju drugačiju, uniformniju distribuciju po dubini ispitivanih profila zemljišta.

Determination of full energy peak efficiency is one of the most important tasks that have to be performed before gamma spectrometry of environmental samples. Many methods, including measurement of specific reference materials, Monte Carlo simulations, efficiency transfer and semi empirical calculations, were developed in order to complete this task. Monte Carlo simulation, based on GEANT4 simulation package and EFFTRAN efficiency transfer software are applied for the efficiency calibration of three detectors, readily used in the Environment and Radiation Protection Laboratory of Institute for Nuclear Sciences Vinca, for measurement of environmental samples. Efficiencies were calculated for water, soil and aerosol samples. The aim of this paper is to perform efficiency calculations for HPGe detectors using both GEANT4 simulation and EFFTRAN efficiency transfer software and to compare obtained results with the experimental results. This comparison should show how the two methods agree with experimentally obtained efficiencies of our measurement system and in which part of the spectrum do the discrepancies appear. The detailed knowledge of accuracy and precision of both methods should enable us to choose an appropriate method for each situation that is presented in our and other laboratories on a daily basis. (C) 2014 Elsevier B.V. All rights reserved.

Active charcoal detectors are used for testing the concentration of radon in dwellings. The method of measurement is based on radon adsorption on coal and measurement of gamma radiation of radon daughters. The contributions to the final measurement uncertainty are identified, based on the equation for radon activity concentration calculation. Different methods for setting the region of interest for gamma spectrometry of canisters were discussed and evaluated. The obtained radon activity concentration and uncertainties do not depend on peak area determination method. (C) 2013 Elsevier Ltd. All rights reserved.

The study of spatial distribution of activity concentration of 238U, 226Ra, 210Pb, 232Th, 40K, and 137Cs radionuclides in the surface soil samples (n = 42) collected in the vicinity of four coal-fired power plants in Serbia is presented. Radioactivity measurements in soils performed by gamma-ray spectrometry showed values [Bqkg-1] in the range: 15-117 for 238U, 21-115 for 226Ra, 33-65 for 210Pb, 20-69 for 232Th, 324-736 for 40K, and 2-59 for 137Cs. Surface soil radio-activity that could have resulted from deposition of radionuclides from airborne discharges or resuspension of ash from disposal sites showed no enhanced levels. It was found that variation of soil textural properties, pH values, and carbonate content influenced activity levels of natural radionuclides while radiocesium activities were associated with soil organic matter content. Modification of some soil properties was observed in the immediate vicinity (

Air sample monitoring in Serbia, Belgrade started in the 1960s, while Be-7 activity in air and total (dry and wet) deposition has been monitored for the last 22 years by the Environment and Radiation Protection Department of the Institute for Nuclear Sciences, Vinca. Using this data collection, the changes of the Be-7 activity in the air and the total (wet and dry) deposition samples, as well as their correlation with meteorological parameters (temperature, pressure, cloudiness, sunshine duration, precipitation and humidity) that affect Be-7 concentration in the atmosphere, were mathematically described using the Fourier analysis. Fourier analysis confirmed the expected; the frequency with the largest intensity in the harmonic spectra of the Be-7 activity corresponds to a period of 1 year, the same as the largest intensity frequency in Fourier series of meteorological parameters. To analyze the quality of the results produced by the Fourier analysis, we compared the measured values of the parameters with the values calculated according to the Fourier series. Absolute deviations between measured and predicted mean monthly values are in range from 0.02 mBq/m(3) to 0.7 mBq/m(3) for Be-7 activity in air, and 0.01 Bq/m(2) and 0.6 Bq/m(2) for Be-7 activity in deposition samples. Relatively good agreement of measured and predicted results offers the possibility of prediction of the Be-7 activity. (C) 2016 Elsevier Ltd. All rights reserved.

Investigation of the natural radioactivity levels in water around power plants, as well as in plants, coal, ash, slag and soil, and to assess the associated radiation hazard is becoming an emerging and interesting topic. This paper is focused on the results of the radioactivity analysis in waste water samples from five coal fired power plants in Serbia (Nikola Tesla A, Nikola Tesla B, Kolubara, Morava and Kostolac), which were analyzed in period 2003–2015. River water samples taken upstream and downstream from the power plants, drain water as well as overflow water were analyzed. In the water samples gamma spectrometry analysis was performed as well as determination of gross alpha and beta activity. Natural radionuclide 40 K was detected by gamma spectrometry, while the concentrations of other radionuclides, 226 Ra, 235 U and 238 U usually were below the minimum detection activity (MDA). 232 Th and artificial radionuclide 137 Cs was not detected in these samples. Gross alpha and beta activity were determined by α / β low level proportional counter Thermo Eberline FHT 770 T. In the analyzed samples, gross alpha activity ranged from MDA to 0.47 Bq L − 1 , while the gross beta activity ranged from MDA to 1.55 Bq L − 1 .

The activity concentrations of natural radionuclides ((40)K, (210)Pb, (210)Po, (226)Ra and (228)Ra) in 17 most frequently used cigarette brands in Serbia and corresponding effective doses due to smoke inhalation are presented. The mean annual effective doses for (210)Pb and (210)Po were estimated to be 47.3 and 724 µSv y(-1) for (210)Pb and (210)Po, respectively. Serbia currently has the highest smoking rate in the world. The results of this study indicate the high contribution of the annual effective dose due to smoke inhalation to the total inhalation dose from natural radionuclides. The more effective implementation of actions for reducing smoking prevalence in Serbia is highly needed.

The results referring to radioactivity analysis in soil, water, plant, coal, slag and flying ash samples from the environment around two power plants Nikola Tesla A and Kolubara for 2015 are explained. The analysis of samples was performed by gamma spectrometry using HPGe detector. In the investigated soil, flying ash, slag and coal samples, naturally occurring radionuclides Ra-226, Th-232, K-40, U-235, U-238, as well as the man-made radionuclide Cs-137, were detected. The highest values of natural radionuclides were obtained in flying ash samples, which is known for the effect of concentrating the combustion of coal. In plant samples, beside these radionuclides, Pb-210 and 7Be were also detected. In water samples, Ra-226 and K-40 were detected, while the concentrations of Th-232, U-235, U-238 and Cs-137 were below the minimum detectable concentration. In water (river, drinking, drain and overflow) samples, beside the gamma spectrometry analysis, gross alpha and gross beta activity was also determined. The obtained values for gross alpha and beta activity in these water samples are in accordance with the current legislation in Serbia (Official Gazette 86/11), which refers only to drinking water. The results presented in this paper showed that there was no significant difference in the activity of radionuclides in all investigated samples compared to the values obtained in previous years. 4th International Conference on Radiation and Applications in Various Fields of Research (RAD), Proceedings, May 23-27, 2016, Nis, Serbia

Specific activity of tritium (H-3) in precipitation and specific activity of Cs-137 in ground-level air were monitored at three locations in Belgrade (Meteorological Station of Belgrade at Zeleno Brdo (ZB), Meteorological Station Usek (USEK), and Vina Institute of Nuclear Sciences (VINS)). Data presented cover the period 1985-1997 for Cs-137 for all locations and 1985-2009 (ZB), 1988-1997 (USEK), and 1988-2009 (VINS) for H-3. Concentrations of H-3 in precipitation have been determined using electrolytic enrichment and liquid scintillation spectrometer LKB-Wallac 1219 RackBeta. The activity of Cs-137 in air was determined on an HPGe detector (Canberra, relative efficiency 23 %). H-3 concentrations in precipitation ranged from 0.40 +/- 0.08 to 74.6 +/- 5.2 Bq l(-1) decreasing with distance from the nuclear facilities. Significantly higher tritium levels were measured in samples in VINS compared with those from an off-site location. The observed seasonal variations of tritium concentration indicate the stratospheric source of tritium. Increases in activity concentration of Cs-137 in the atmosphere were observed after the nuclear plant accident at Chernobyl in April 1986. The concentrations obtained for Cs-137 in 1986 were compared with the integrated air concentrations of Cs-137 in the region. The increases of Cs-137 air concentrations in 1987 and 1988 were attributed to local resuspensions from the ground. Since 1989, the activity level before the accident has been obtained. The average monthly concentrations of Cs-137 in ground-level air were shown spread maximum in spring-summer period and pronounced maximum during winter. The obtained results were statistically analyzed, i.e., the following parameters were determined: tritium deposition, monthly activities of H-3 and Cs-137, seasonal indices, radionuclide loading indices, and linear correlation coefficients.

Natural resources such as ores contain radioactive nuclides at various concentrations. Therefore it is important to investigate the radioactivity in these resources as well as in the soil at the locations of ore deposits. For that reason we conducted preliminary measurements in the soil samples taken from the locations of lead and zinc ore deposits in Bosilegrad and Raška and from the locations of phosphate ore deposits in Bosilegrad to estimate the environmental conditions prior to the ore excavation. The activity concentrations of radionuclides in soil, water and plant samples were determined by gamma spectrometry (HPGe detector, relative efficiency 23%). Results showed the presence of natural radionuclides (226)Ra, (232)Th, (40)K, (235)U, (238)U as well as the produced radionuclide (137)Cs (from the Chernobyl accident). Ambient gamma radiation dose rate in ground level air was also measured. In order to estimate the influence of subsequent mining on the working and living environment, radium equivalent (Ra(eq)), external hazard index (H(ex)), external gamma absorbed dose rate ([Formula: see text]) and annual effective dose (D(E)) were determined.

Due to the influence of a number of high-risk factors - continuous destruction of nature environment, poor quality management of medical and municipal waste, widespread use of immuno-suppressive therapy, high resistance to antibiotics, social transformation, risky behavior of people etc., the infectious diseases continue to pose a serious threat to health. The main aim of this paper is to present the infectious and parasitic diseases trend, as health problems in the Belgrade municipality of Zvezdara. The method of descriptive analysis has been used in processing of data obtained from the individual report cards of infectious diseases, delivered from the Primary Health Center 'Zvezdara' in the period 2006-2010. Our research reveals that in the afforementioned period a total of 6.132 infectious diseases was registered: mostly droplet (86,3%), significantly less intestinal (10,3%), parasitic only 0,5% and others 2,9%. The maximum appearance frequency of these diseases was recorded (1.835) in 2007, whereas it was the lowest (886) in 2010. Throughout the time interval considered variccela, scarlatina and angina streptococcica were dominating. Regarding the age, more than a half of all infectious diseases were registered in the population of infants and among young children. In spite of the assessment obtained from the data available in the considered period that the community-based epidemiological situation was relatively calm, we firmly believe that, unfortunately, the actual number of infectious diseases is several times greater. That is mostly the consequence of extremely nonstandard disease reporting, being still considered as a purely administrative task and not as a primary legally and compulsory measure.

The paper presents results of a long-term investigations of tritium activity concentrations in precipitation and radiocesium activity concentrations in ground level air in Belgrade, Serbia. Samples were collected at three locations in Belgrade (Meteorological Station of Belgrade MS at Zeleno Brdo (ZB), Meteorological Station MS Usek (USEK), and Vinca Institute of Nuclear Sciences (VINS)). Presented data cover the period 1985-1997. Significantly higher tritium levels were measured in samples in VINS compared with off-site location, while the impact of research reactor for Cs-137 was not detected. It was found that the value of the symmetrical index n is higher for VINS in case of tritium, compared to other locations, which is in accordance with the fact that the highest average monthly concentrations of tritium were obtained in the samples from the cited place. Although the highest value of index n in case of Cs-137 was also obtained for VINS, average monthly concentrations of Cs-137 in ground level air for this location were the lowest. The Cs-137 concentration in the ground level air is described by a kinetic equation of the first order and provides a good description of the time changes in these concentrations.

Four different kinds of materials (feldspar, gypsum, clay and kaolin) commonly used in building construction and industry in Serbia were analyzed for their natural radioactivity, using gamma spectrometry. The radium equivalent activity, Ra(eq), the absorbed dose rate, D, the annual effective dose, DE, and the external hazard index, H(ex), were evaluated to assess the radiation hazard for people living in dwellings made of the materials studied. The radium equivalent activities calculated in all samples are lower than the maximum admissible value 370 Bq kg(-1) set in the UNSCEAR report.([1]) The absorbed dose rate in air was found to vary from 0.02 to 0.19 mu Gy h(-1). Considering the fact that the average gamma dose rate indoors in Europe is 0.07 mu Gy h(-1[2]), gamma dose rate calculated for feldspar, clay and kaolin samples exceed this limit. The obtained results for annual effective dose exceed limits of 0.41 mSv([1]) for feldspar, clay and kaolin samples. If the H(ex) exceeds unity, we might conclude that the potential external dose(s) to exposed individual(s) will exceed the acceptable level, and some action may be required. The obtained values of H(ex) are lower than unity for all investigated samples. All samples were measured immediately after preparation, except 10 samples of feldspar, because a comparative analysis were made between 215 samples which were measured immediately after preparation and 10 samples which were measured after radioactive equilibrium was reached in order to detect differences in the obtained concentrations.

To assess the validity of the moss bag monitoring technique in the radioactivity control of ground level urban air, a study on radionuclide contents in moss was performed in the city of Belgrade, Serbia. From May 2006 to May 2007, moss (Sphagnum girgensohni, Dubna, Russia) was exposed to the aero pollution in a location in the central area of the city. The activity of 40K, 210Pb, and 137Cs was measured on an HPGe detector (Canberra, relative efficiency 23%) by standard gamma spectrometry. The activities 245 ± 25 Bq/kg for 40K, 315 ± 34 Bq/kg for 210Pb, and 28 ± 4 Bq/kg for 137Cs are in the range of values reported for the region; the differences are due to the moss species, local climate and measuring technique. Taking into consideration the time of the exposure and appropriate calibration procedure, moss bag biomonitoring could be used as a complementary method for determination of radionuclides in urban air. U cilju utvrđivanja valjanosti tehnike aktivnog monitoringa pomoću mahovina u kontroli radioaktivnosti prizemnog sloja atmosfere, na teritoriji grada Beograda sprovedena je studija sadržaja radionuklida u mahovinama. Od maja 2006. do maja 2007. godine, mahovina (Sphagnum girgensohni, Dubna, Rusija) izlagana je vazdušnom zagađenju na lokaciji u centru grada. Koncentracija aktivnosti 40K, 210Pb i 137Cs merena je HPGe detektorom (Canberra, relativne efikasnosti 23%) metodom standardne gama spektrometrije. Koncentracije aktivnosti od 245 ± ± 25 Bq/kg za 40K, 315 ± 34 Bq/kg za 210Pb i 28 ± 4 Bq/kg za 137Cs spadaju u opseg vrednosti izmerenih u regionu; razlike u rezultatima potiču od vrste mahovine, lokalne klime i tehnike merenja. Uzimajući u obzir vreme izlaganja i pravilnu proceduru kalibracije, aktivni monitoring mahovinama može da se primeni kao komplementarni metod za određivanje koncentracije radionuklida u vazduhu u urbanom području.

During 2005 and 2006, soil samples were collected from different regions in the Republic of Srpska, in order to evaluate their radioactivity. During the war that lasted from 1994 to 1995, it is known that some locations in the Republic of Srpska were imposed upon by NATO forces. Sampled locations were chosen far away from the bombed places in order to check whether the depleted uranium was dispersed over long distances. The activity concentrations of radionuclides in soil samples were determined by gamma spectrometry (HPGe detector, relative efficiency 23%). Results showed the presence of natural radionuclides 226 Ra , 232 Th , 40 K , 235 U , 238 U as well as the produced radionuclide 137 Cs (from the Chernobyl accident and nuclear probes). In order to evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the gamma-absorbed dose rate, the annual effective dose rate and the external hazard index have been calculated.

The effect of the density of environmental samples on the counting efficiency of Ge detectors used in gamma-spectrometry was studied. The dependence εff(ρ) was determined for two HPGe detectors (relative efficiencies 18% and 20%) using five radioactive standard reference materials (silicone resins, epoxy resin, milk powder, soil) with different matrix densities (0.45-1.22 g/cm3) in Marinelli beakers (V = 500 cm3). The dependence of efficiency vs. density was found to be linear and the regression parameters for energies in the range of 60-2000 keV were determined, too. The effect of variation in density on the counting efficiency of Ge detectors is dominant in the range of lower energies (60-600 keV) and de creases with energies in the higher energy range. Ispitivan je uticaj gustine uzoraka iz životne sredine na efikasnost brojanja germanijumskih detektora u spektrometriji gama zračenja. Zavisnost εff(ρ) određena je za dva HPGe detektora (relativnih efikasnosti 18% i 20%) za različite radioaktivne standardne referentne materijale (silikonske smole epoksi smolu, mleko u prahu, zemlju) različitih gustina (0,45-1,22 g/cm3) u Marineli posudama zapremine V = 500 cm3. Utvrđena je linearna zavisnost efikasnosti brojanja od gustine uzoraka pri čemu su određeni parametri linearne regresije za niz energija iz intervala od 60-2000 keV. Efekt promene gustina na efikasnost brojanja germanijumskih detektora dominantan je u intervalu nižih energija (60-600 keV) i smanjuje se sa porastom energije u intervalu viših energija.

This work presents a comprehensive study of natural radioactivity in 720 building materials imported in Serbia in 2012. Radioactivity concentrations of Ra-226, Th-232 and K-40 in the studied samples range from LT 5 to 4,938, LT 3 to 763 and LT 10 to 3,192 Bq kg(-1), respectively. The maximum values of Ra-226 and Th-232 activity concentrations were found in zirconium mineral, while the highest K-40 activity concentration was in the feldspar. Based on the obtained radionuclide concentrations, radium equivalent activity, air absorbed dose rate, annual effective dose, external and internal hazard indices, gamma and alpha index due to radon inhalation were evaluated to assess the potential radiological hazard associated with these building materials.

This paper is focused on the results for activity concentrations of Be-7 in depositions recorded in Vina Institute of Nuclear Sciences, as part of radioactivity monitoring in Institute from 1994 to 2013. year. Samples were collected on a monthly basis and activities were present on sampling day (middle of the month). The activities were determined on HPGe detectors by standard gamma spectrometry, and they ranged from 0.05 to 10.4 Bq m(-2). The obtained results were statistically analyzed. The Be-7 activity shows a pronounced seasonal pattern, with the maximum in spring-summer and minimum in winter.

The homogeneity of fertilizer samples for interlaboratory γ-ray spectrometry comparison was tested by determination of the total γ count rate and the count rates for two 238U γ lines, one 40K line and one common 235U and 226Ra line. Homogeneity testing was accomplished by determination of the minimum, maximum, mean and standard deviation for each parameter and comparison of their standard deviations with predefined tolerances, by Cochran’s test, and by a one-way ANOVA. The standard deviations were all less than these tolerances. All samples passed Cochran’s test and the one-way ANOVA test for homogeneity.

Measurement of the gross alpha and beta activity concentrations in various matrices is suitable as a preliminary screening procedure to determine whether further analysis related to specific radionuclide is necessary. In Serbia, according to current regulations, radioactivity concentrations in drinking water for gross alpha and gross beta should be < 0.5 and < 1.0 Bq L−1, respectively. The generally accepted methods for gross alpha and beta activity analysis of drinking water in different countries are: EPA 900.0 and ISO methods (ISO 9696, water quality – measurement of gross alpha activity in non-saline water – thick source method, and ISO 9697, water quality – measurement of gross beta activity in non-saline water). This paper describes comparison of preparations and measurement gross alpha and beta activity in bottled mineral waters as well as in tap waters in Serbia using two methods: EPA 900.0 with and without ash, and ISO methods. Concentration of total dissolved solids (TDS) in investigated water samples was determined. Based on obtained TDS, certain volume was evaporated. The instrumentation used to count the gross alpha and gross beta activities for both methods is α/β low level proportional counter Thermo Eberline FHT 770 T.

The paper presents the results of indoor radon concentration survey in 201 homes and offices in Niska Banja (the Spa of Nis), a well-known health resort and a spa in the South-East of Serbia. Radon indoor concentrations were determined by active charcoal method, according to standard EPA procedure. The indoor radon concentrations were in the range of up to 200 Bq/m3 (47%), from 200–600 Bq/m3 (26%) and over 600 Bq/m3 (27%). Three areas of extremely high average radon concentrations were found (1340–4340 Bq/m3), with a maximum above 13,000 Bq/m3.The content of natural radionuclides (226Ra, 214Pb, 214Bi, 235U, 228Ac, 212Pb, 212Bi, 208Tl, 40K) and 137Cs, as well as the content of total uranium, thorium and potassium in mud used in peloidotherapy in the Health Institute “Niska Banja” was determined, too. The activities of the radionuclides were determined on an HPGe detector, by standard gamma spectroscopy. The results indicated considerably high amounts of total uranium and thorium (0.021 g/kg mud and 0.003 g/kg mud, respectively), due to the karsts origin of the soil. Keywords: Radon in air, Radionuclides, Soil, Spa, Gamma spectroscopy

The paper presents the results of radon indoor concentrations measurements in homes and public institutions (kindergardens) in Belgrade, as well as the results of the radionuclides content determination in building materials from Serbia, during the eighties and up to the mid-nineties of the 20th century. The activity of the radionuclides was determined on an HPGe detector (ORTEC relative efficiency 20%) by standard gamma spectrometry. Radon indoor concentrations on the grab samples of air were determined by alpha scintillation technique (Lucas scintilation cell with ZnS/Ag). Mean effective dose equivevalents of radon and its progenies in closed space were estimated at 0.074 mSv for radon and 1.22 mSv for its short-lived daughters, in total 1.3 mSv.

7Be to 210Pb concentration ratios in ground level air on two monitoring stations (MS1 and MS2) in Belgrade area were determined from 1996 to 2001. The average monthly concentrations of 7Be in ground level air were in the range of 0.6-18.3 mBq/m3 and exhibited one or two summer/early fall maxims and one minimum in winter. The maximum concentrations for 210Pb were generally observed in the fall, with the average concentrations in the range of 1.09 x 10(-4) to 30.9 x 10(-4) Bq/m3. The 7Be/210Pb ratios were in the range of 1.7-12.7 (MS1) and 1.8-11.3 (MS2), with summer maxims and late fall/winter minimums. The mean Radionuclides Loading Indices values approach zero except for 1996/1997 (MS1) and 2001 (MS2) due to higher concentrations of 7Be and 210Pb. The mean monthly concentrations of both radionuclides exhibited lognormal distributions. There is significant correlation between the 7Be/210Pb activities ratio and the air stability classes A + B + C for both monitoring stations (correlation coefficients 0.61-0.65), and no correlation with D class and E + F classes. Correlation was found between the activity of 7Be and air stability classes A + B + C (0.46-0.68), and E + F (0.38 for MS1), while for 210Pb, a moderate correlation (0.38-0.40) was found with the E + F air stability classes.

A phenomenological model of a tumor interacting with the relevant cells of the immune system is proposed and analysed. The model has a simple formulation in terms of delay-differential equations (DDEs). The critical time-delay, for which a destabilising Hopf bifurcation of the relevant fixed point occurs, and the conditions on the parameters for such bifurcation are found. The bifurcation occurs for the values of the parameters estimated from real data. Local linear analyses of the stability is sufficient to qualitatively analyse the dynamics for small time-delays. Qualitative analyses justify the assumptions of the model. Typical dynamics for larger time-delay is studied numerically.

This study focuses on determination of soil to plant transfer factor (TF) of long lived radionuclides 90Sr and 137Cs. 90Sr and 137Cs activity concentration in agricultural soil samples was ranged between

The charcoal canister method of radon measurement according to US Environment Protection Agency protocol 520/5-87-005 is widely used for screening. This method is based on radon adsorption on coal and measurement of gamma radiation of radon daughters. For the purpose of gamma spectrometry, appropriate efficiency calibration of the measuring system must be performed. The most usual method of calibration is using standard canister, a sealed canister with the same matrix and geometry as the canisters used for measurements, but with the known activity of radon. In the absence of standard canister, a different method of efficiency calibration has to be implemented. This study presents the results of efficiency calibration using the EFFTRAN efficiency transfer software. Efficiency was calculated using a soil matrix cylindrical secondary reference material as a starting point. Calculated efficiency is then compared with the one obtained using standard canister and applied to a realistic measurement in order to evaluate the results of the efficiency transfer. 2nd International Conference on Radiation and Dosimetry in Various Fields of Research RAD and The 2nd East European Radon Symposium (SEERAS), May 27-30, 2014, Nis, Serbia

To assure that radiological monitoring is reasonably valid, organisations performing such measurements have found it necessary to establish quality assurance (QA) and quality control (QC) programs. These programs are needed to identify deficiencies in the sampling and measurement processes. In addition, validation of the monitoring aims to prove whether the results are acceptable. The major aim of QA and QC in analytical laboratories is to address measures used to verify the validity of the final results. In the document ISO 17025 the requirements on how to achieve QA and QC in analytical laboratories is described. All proposed measures for QC/QA are implemented in the Radiation and Environment Protection Department of Institute for Nuclear Sciences in Vinca, Belgrade. This paper presents the summarisation and analysis of QC and QA measures undertaken by the Laboratory for Environmental and Radiation Protection of the Vinca Institute of Nuclear Sciences. Total of 6 months of QC/QA charts are presented in this paper for 2 HPGe gamma spectrometry detectors and one gross alpha/beta detector. The data were analysed and conclusions were made concerning the stability of the measurement systems. In cases of unsatisfactory behaviour of the system, some correctional measures are proposed and conducted and the effect on the measurement system is discussed.

In the 1999 bombing of the Federal Republic of Yugoslavia, NATO forces used ammunition containing depleted uranium. The cleaning of depleted uranium that followed was performed in southern Serbia by the Vinča Institute of Nuclear Sciences between 2002 and 2007 at the locations of Pljačkovica, Borovac, Bratoselce, and Reljan. This paper presents detailed results of radioactivity monitoring four years after cleaning (2011), which included the determination of gamma emitters in soil, water, and plant samples, as well as gross alpha and beta activities in water samples. The gamma spectrometry results showed the presence of natural radionuclides 226Ra, 232Th, 40K, 235U, 238U, and the produced radionuclide 137Cs (from the Chernobyl accident). In order to evaluate the radiological hazard from soil, the radium equivalent activity, the gamma dose rate, the external hazard index, and the annual effective dose were calculated. Considering that a significant number of people inhabit the studied locations, the periodical monitoring of radionuclide content is vital.

The determination of radionuclide activity concentration requires a prior knowledge of the full-energy peak (FEP) efficiency at all photon energies for a given measuring geometry. This problem has been partially solved by using procedures based on Monte Carlo simulations, developed in order to complement the experimental calibration procedures used in gamma-ray measurements of environmental samples. The aim of this article is to apply GEANT4 simulation for calibration of two HPGe detectors, for measurement of liquid and soil-like samples in cylindrical geometry. The efficiencies obtained using a simulation were compared with experimental results, and applied to a realistic measurement. Measurement uncertainties for both simulation and experimental values were estimated in order to see whether the results of the realistic measurement fall within acceptable limits. The trueness of the result was checked using the known activity of the measured samples provided by IAEA.

Concentrations of 210 Pb in ground level air in the city area (Belgrade, Central Serbia) were measured in the period from 1985 to 1996. The activity of 210 Pb in air filters was determined on a HPGe detector by standard gamma spectrometry. Total standard error of the method was estimated to be below 25%. The average monthly concentrations of 210 Pb in the ground level air in the period from 1985 to 1996 were in the range of 0.30–3.17 mBq m−3 with the maxima in fall–winter periods and minimums in springs and early summers. The seasonal indices were 1.12–1.59 for fall–winter and 0.77–0.92 for spring–summer periods. The ratios of maximum-to-minimum concentrations in each year were relatively stable over the period, with slight increase in 1985, 1989 and 1995. The investigations are part of the long-term measurements of natural and man-made radionuclides in the ground-level air in the region.

Concentrations of 7 Be and 137 Cs in ground level air in the city area (Belgrade, central Serbia) were determined in the period from 1991–1996. The average monthly concentrations of 7 Be in ground level air were in the range of 2–7 mBq/m 3 with pronounced one or two maxima in summer or early fall and a minimum in winter. The average air concentrations for 137 Cs were from 0.5–8.5 × 10−5 Bq/m 3 , with a spread maximum in the spring-summer period and a pronounced maximum during the winter. A general increase in 7 Be and 137 Cs concentrations during 1993 was recorded. The maximum seasonal indices were 1.3 for 7 Be (summers) and 2.7 (late springs and early summers) and 3.4 (winters) for 137 Cs. No correlation with the amount of precipitation and 137 Cs concentrations in air was determined, while the washout effect of rainfalls seems to be more closely related with variations in 7 Be concentrations.

The effect of tropopause height on the content of Cs-137 and total beta activity in surface atmosphere was considered for the period of intensive nuclear weapon tests, from 1968-1971. The activity of Cs-137 in monthly air filter samples was measured by gamma spectrometry and total beta activity was determined by 2 pi proportional counters. The results were correlated with data on tropopause height. The results indicate that the movement of radioactive debris from the stratosphere into the troposphere occurs simultaneously with the changes in tropopause height. The content of long lived radionuclides in the troposphere follows the changes with a certain delay due to meteorological conditions in surface air and due to the location of sampling. (C) 1997 Elsevier Science Ltd.