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The paper discusses the structural behaviour of concrete-filled steel tube columns (CFT) when applied to the top-down construction method as temporary internal supports for ceilings. Their ultimate capacity to take into account the actual boundary conditions of the column is essential for successful application in construction. The paper presents the full-scale in situ testing of four slender specimens with variable D/t ratios under concentric axial loading. The CFT columns were supported on the previously jacked concrete piles. In addition, detailed finite element numerical models in ABAQUS and PLAXIS computer programs were developed. The models include the nonlinear behaviour of materials and the nonlinear behaviour of soil. The soil–pile–column interaction and impact of the CFT column–pile connection stiffness on global column stability were considered. The numerical model was validated by comparison with the experimental results. In conclusion, the coefficient for the effective buckling length of the studied columns is proposed. Finally, the experimental results of the critical buckling forces were compared with widely used international design codes Eurocode 4-EC4, American standard-ACI and the Australian standard-AS.

Doses from the exposure to outdoor radon are typically an order of magnitude smaller than those from indoor radon, causing a greater interest on investigation of the latter for radiation protection issues. As a consequence, assessment of radon priority areas (RPA) is mainly based on indoor radon measurements. Outdoor radon measurements might be needed to guarantee a complete estimation of radiological risk and may help to improve the estimation of RPA. Therefore, authors have analysed the available literature on outdoor radon to give an overview of outdoor radon surveys and potential correlation with indoor radon and estimation of RPA. The review has shown that outdoor radon surveys were performed at much smaller scale compared to indoor radon. Only a few outdoor radon maps were produced, with a much smaller density, covering a larger area, and therefore putting doubt on the representativeness of this data. Due to a large variety of techniques used for outdoor radon measurements and requirement to have detectors with a high sensitivity and resistance to harsh environmental conditions, a standardised measurement protocol should be derived. This is no simple endeavour since there are more applications in different scientific disciplines for outdoor radon measurements compared to indoor radon.

Metodom gamaspektrometrije u periodu 2020-2021. godina praćena je koncentracija aktivnosti radionuklida u površinskoj vodi i rečnom sedimentu reke Dunav, na teritoriji beogradske opštine Zemun. U ovom radu su prikazane vrednosti izmerenih koncentracija aktivnosti detektovanih radionuklida. Dok se u uzorcima površinske vode praktično detektuje samo prisustvo 40K i 226Ra u koncentracijama reda nekoliko desetina mBq/l, u uzorcima sedimenta detektovani su prirodni radionuklidi u navedenim opsezima koncentracija : 226Ra - (14-46) Bq/kg, 232Th - (17-56) Bq/kg, 40K - (230-645) Bq/kg, 238U - (15-53) Bq/kg i 235U - (1,2-3,2) Bq/kg.

The operation of coal fired power plants greatly influences the surrounding environment, especially water and soil, due to large amounts of combustion waste products released. Besides the quality of soil and water from the aspect of chemical and structural composition (release of heavy metals, ash and slag deposition on soil) it is of at most importance to maintain a strict control from the radiological safety point of view. All coal types contain certain amount of naturally occurring radionuclides, which depends on the composition of the rock and soil adjacent to the place of the coal excavation. These radionuclides are concentrated in the process of coal combustion, thus leading to potentially high levels of radioactivity in the ash and slag. These by – products are released into the environment and can increase the radiation burden on the environment, change the composition of the soil and bodies of water in the vicinity, thus potentially influencing the health of the general population. In this paper, the radiological analysis of soil and water samples taken from the vicinity of different coal fired power plants in Serbia in the period of 2019-2021. will be presented. Measurements are performed in the Radiation and Environmental Protection Department of Institute of Nuclear Sciences Vinča within the framework of regular environment monitoring of the power plants.

Radiostrontium is released to the environment during the testing and use of nuclear weapons mainly in the fifties and sixties of XX century, in addition to nuclear power plant accidents (to some extent in 1986 owing to the Chernobyl accident) and the nuclear fuel reprocessing industry. Strontium is a chemical analogue of calcium (both are earth-alkaline metals) and accordingly when entering a human or animal body, it behaves similar to calcium. A large portion of the strontium will accumulate in bone and teeth and then is included in the metabolism along with Ca, and like calcium, it transfers to milk. Since the strontium uptake by the human body from milk is an important pathway for radiostrontium incorporation, milk and dairy products are good indicators of strontium-90 (Sr-90) content in human diet. Based on the mentioned, the knowledge about Sr-90 content in milk and dairy products is of extreme importance to prevent and control contamination of the food chain. The present study was conducted in order to radiologically control for Sr-90 content in raw milk and some dairy products samples composed of representative locally purchased milk. The analyses are performed using radiochemical analytical oxalate precipitation method, whereby interfering radionuclides are removed by precipitation scavenging. Yttrium-90 (Y-90) is generated from the beta decay of Sr-90. After the ingrowth Y-90 is separated and equilibrium is established, the samples are measured by gas flow proportional counter. The results of investigation showed that Sr-90 activity concentration in many investigated samples was at a lower level than minimum detectable activity (MDA) of the method.

After the Chernobyl accident, the presence of artificial radionuclides in foodstuff, especially in berries (blueberries, cranberries etc.), was heightened. Legislative, presented in Rulebook on Radioactivity Control of Goods During the Import, Export and Transit (Official Gazette RS, 86/19 and 90/19), establishes the mandatory gamma spectrometry measurement of berries, while the limits of radionuclide content in these products is defined in the Rulebook on Limits of radionuclide content in drinking water, foodstuff, feedstuff, medicines, items of general use, building materials and other goods placed on the market (Official Gazette RS, 36/18). At the Radiation and Environment Protection Department of the Vinča Institute of Nuclear Sciences, measurements of the radionuclide activity in foodstuff are readily performed. In this paper, the results of the investigation of berries in the period of 2014 to 2021 are presented along with the amount of this produce that can be ingested by the various age groups without exceeding the annual effective dose limit of 0.1 mSv.

In accordance with ISO/IEC 17025:2017 - General requirements for the competence of testing and calibration laboratories, the laboratory needs to verify its ability to properly perform methods before introducing them, by ensuring it can achieve the required performance (article 7.2.1.5). Also, if a laboratory carries out a sampling of a material, it needs to have a sampling plan and method established (article 7.3.1). In laboratories dealing with radionuclide content testing, the sampling does not affect the testing results directly, but the sampling procedure has to ensure that the taken and later measured sample adequately represents the tested material. In order to verify the sampling procedure for the needs of radiological tests, a sampling of red mud (13 samples) and bauxite ore (6 samples) was conducted in the aluminum factory “Alumina ltd”, Zvornik, Bosnia and Herzegovina in June 2021. In accordance with the established sampling procedure, GPS coordinate and ambient dose rate were recorded for each sample. Samples were prepared in accordance with IAEA, TRS 295 (1989), placed into identical PVC cylindrical boxes and measured by HPGe gamma spectrometer. Spectra of bauxite and red mud were recorded in 10 consecutive measurements for 21000 s and 6000 s, respectively, in order to achieve good statistic. For the purpose of sampling procedure verification, the counting rates per unit mass in the recorded spectra were compared. For each measurements series, the total counts in the spectrum as well as individual energies mean value and standard deviations were calculated. After the measurements were completed, the average of the each individual series mean values and the associated/corresponding standard deviation were calculated. The measurement result of each individual series is considered satisfactory if, taking into account the calculated standard deviation, it is within +/- two standard deviations of the average of the mean values. The obtained results verified t

Tritium, radioactive isotope of hydrogen, is produced naturally in the upper atmosphere between nitrogen atoms with high energy cosmic rays. Anthropogenic production has disturbed the natural levels of tritium by nuclear atmospheric tests between 1945 and 1963. Tritium is a pure beta emitter with half-life of 12.32 years. Since the main way to eliminate tritium from the atmosphere is through precipitation, whether of natural or artificial origin, tritium easily reaches surface waters and soil from where it can infiltrate into the groundwater and thus enters in the hydrological cycle. Accordingly, knowing the concentration of tritium in precipitation is of essential importance. This paper presents determination of tritium in precipitation collected at Reference Meteorological Station Zeleno Brdo in Belgrade during 2019. Analysis is done in composite monthly samples. Sample preparation involves the first distillation, electrolysis and the second distillation. Samples were measured by Liquid Scintillation Spectrometer Quantulus 1220 after electrolytic enrichment by mixing 8 ml of sample with 12 ml of scintillation cocktail. Tritium activity concentration in analyzed precipitation samples follows normal seasonal variations with maximum in spring-summer months. Based on the monthly amount of precipitation, that is available on the website of the Republic Hydrometeorological Servise of Serbia, it is possible to estimate the deposition of tritium on the earth's surface. The wettest months of 2019 were May and June, and since tritium concentrations are the highest in these months (June: 2.89 Bq/l), the highest value of deposited tritium is obtained in June: 400,8 Bq/m2 . In accordance with the legislation in the Republic of Serbia, the permitted values of tritium are defined only for drinking water (100 Bq/l). An elevated tritium level may indicate the presence of other artificial radionuclides. If an increased activity of tritium is detected, it is necessary to perform an

The main goal of agricultural production should be the production of a sufficient amount of agricultural products with the least possible impact on the environment. In traditional agricultural production, in order to obtain a satisfactory yield, artificial fertilizers are used, which have multiple negative impacts on the environment. Glassy fertilizers are a type of fertilizer that, at least according to previous research, do not have a negative impact on the environment and the same time the use of these fertilizers yields not less than when using traditional fertilizers. Glassy fertilizers are fertilizers with controlled dissolution, they do not pollute groundwater or surface water, the pH of the soil does not change with their use, by changing the composition they can adapt to the requirements of each crop individually, etc. The paper presents three phosphate glassy fertilizers of different chemical composition, obtained at the Center for Inorganic Technologies, ITNMS. The method of obtaining of glassy fertilizers, their dissolution rates in a medium that simulates soil conditions, the changes in pH values of solutions for different dissolution times and the effect of temperature on dissolution rates are shown. Also, the results of the influence of glass fertilizers on plant cultures in real conditions are presented.

Fosfatna stakla imaju jedinstveno svojstvo da se mogu potpuno rastvoriti u vodenim rastvorima, a brzina rastvaranja može da se kontroliše. Proces rastvaranja stakla počinje razmenom katjona sa površine stakla sa protonima iz rastvora (H+ ili H3O+) i hidratacijom staklene mreže. Početna brzina rastvaranja je osnovna karakteristika rastvaranja stakla. Analiza početnih brzina rastvaranja fosfatnog stakla, koje je dobijeno topljenjem, pokazuje da su brzine značajno veće u kiseloj sredini u odnosu na brzine rastvaranja u neutralnoj. Granulacija uzorka ima veći uticaj na početne brzine u neutralnoj sredini. Granulacija uzorka ne utiče na vrednost energije aktivacija početnih brzina rastvaranja u obe sredine. U neutralnoj sredini temperatura manje utiče na hidrolizu, a više na difuziju katjona, dok je u kiseloj sredini suprotno.

Global trends are moving towards a circular economy to replace the deeply grounded one linear economics and waste management. Circular economy implies and the protection of human rights through sustainable development, global security natural resources, combating climate change, energy security, insurance sufficient amounts of food, reducing inequalities, preservation of health and a cleaner environment and the rights of future generations to resources, etc. The policy of procurement of raw materials in the circular economy is focused on the use of secondary raw materials. A big challenge for modern production is to use different types of waste to obtain new products without the use of raw materials. This kind of production requires new knowledge, adaptation of existing technologies or new technologies, new jobs, etc. Large amounts of vegetative residues are produced annually by agriculture. Agricultural waste is very often incinerated or disposed of on land and is still not used. Most of the agricultural waste ashes consist of silicon dioxide along with other oxides which may vary according to region and atmosphere of the local conditions. This paper gives an overview of the possibilities of using agricultural waste for obtaining glass and glass ceramics. Previous research has shown that various types of glass and glass-ceramics can be successfully obtained from agricultural waste, which can be used in construction, medicine, various composites, etc.

The purpose of this study is to investigate the influence of La2O3 addition on the crystallization characteristics of polyphosphate glasses. Differential scanning calorimetry (DSC), and X-ray diffraction (XRD) methods were used to investigate the crystallization behavior of glasses. The addition of La2O3 (1-5%), at the expense of phosphate mole fraction in polyphosphate glass, raises the characteristic temperature of glasses, and resistance to crystallization. The glasses show complex crystallization leading to the formation of several crystalline phases

The increasing production of coal fly ash waste from thermal power plants has compounded environmental and economical problems worldwide. In this research coal fly ash was mixed with glass cullet and CaCO3 and melted at T= 1500 °C. The glass was milled, pressed and sintered at T= 900 °C to obtain glass- ceramic. Obtained glass- ceramic was well sintered with low crystallinity. This material, produced from secondary raw materials, could find potential application in building industry as substitute for commercial wall and floor tiles.

The crystal growth rate of lithium germanium-phosphate glass was studied. The glasses have been homogenized using the previously established temperature-time conditions, which make it possible to remove a volatile substances from the glass melt. The AAS was used to determine the chemical content of obtained glass, the differential thermal analysis (DTA), and scanning electron microscope (SEM) were used to reveal the isothermal process of crystal growth, respectively. It has been found that the experimental determined crystal growth rate has a tendency toward of exponentially increase with an increase the temperature.

Potassium germanate glass with the molar ratio 30K2O·34Nb2O·36GeO2 have been synthesized by the standard melt-quenching method. The crystallization behavior under the non-isothermal crystallization conditions was investigated by the DTA and XRD methods. The results showed that this glass exposed a complex primary crystallization.

The nucleation process of lithium germanium-phosphate glass was studied to determine the temperature range of nucleation and the temperature of the maximum nucleation rate. The differential thermal analysis (DTA), and scanning electron microscope (SEM) were used to reveal the nonisothermal and isothermal process of nucleation, respectively. The crystallization process occurred at a high homogeneous nucleation rate and the spherulitic crystal growth morphology. Nanostructured samples were obtained.

Mountain ecosystems are going through changes due to numerous physical-chemical processes in the environment rather than the anthropogenic activities. Primordial radioactivity of rock and soil material migrates and fractionates in other environmental sections like waters, air and biota. Having a feature to accumulate different minerals and trace element present in soil and three substrates, fungi indicates their composition and related processes. The aim of this study is uptake of radionuclides by fungi in the schist soil of the Stara Planina, mountain famous for biodiversity as well as for enhanced natural radioactivity areas. Samples of various fungi species (stipes and cups) and their soil substrates have been collected in summer season 2019. Collected soil samples are pedologically characterized and analysed by gamma-spectrometry (HP Ge) after the secular radioactive equilibrium had been reached. Soil characterization has shown the share of coarse fragments, sand, silt and clay in the schist (shale) structure while pH value was 4.80-5.33 and organic carbon content 3.10%. The content of significant natural radionuclides 40K, 226Ra, 232Th, 238U and manmade 137Cs was (in Bq/kg) was 500±30, 27±2, 26±2, 32±4, 1.6±0.2 respectively. Dried fungi samples were analysed by gamma spectrometry showing the natural radionuclide content in wide range of values. Obtained results indicate dependence of the radionuclides uptake from the substrate on their abundance in schist soil type as well as the fungus specie physiology. Slight difference was observed in results between content in species with different types of nutrient uptake (mycorrhizal and saprobic). The 137Cs content varied from 2-20 Bq/kg. Further knowledge on the local population habits in use of edible fungi species would enable dose assessment for the representatives of the public and contribute to a further research on the Stara Planina mountain ecosystem.

In accordance with ISO/IC 17025:2017 testing laboratory shall have a procedure for monitoring the validity of results that includes regular participation in interlaboratory comparisons. Interlaboratory comparison RADON2021 was organized in the frame of the bilateral project between Serbia and Montenegro: “Measurement of the radon equilibrium factor in typical residential buildings in Serbia and Montenegro and harmonization of radon measurement techniques” in order to assess congruence of different measurement techniques, and then harmonize methods in case of inconsistencies. Harmonization is of particular importance to neighboring countries, in order to avoid inconsistencies in the classification of radon risk zones along border areas. Thus, six regional laboratories took part in the intercomparison – three from Belgrade and one from Novi Sad, Serbia; one from Podgorica, Montenegro; one from Banja Luka, Bosnia and Herzegovina. All laboratories participated in the indoor radon measurements, while 4 laboratories measured radon in the soil also. The measurement methods and detectors used by the laboratories were: • for air - EPA 402-R-92-004 – Indoor Radon and Radon Decay Product Measurement Devices Protocols, ch. 3.1. with RAD 7, RTM1688-2 and RadonEye; EPA 520/5-87-005 – 1987 EERF Standard Operating Procedures for Rn-222 Measurement Using Charcoal Canisters, ch. 3.4 using adsorption on charcoal canisters; ISO 11665- 4: Measurement of radioactivity in the environment – Air Radon 222: Part 4: Integrated measurement method for determining average activity concentration using passive sampling and delayed analysis with Electretes, and • for soil gas - ISO 11665-11:2016 Measurement of radioactivity in the environment — Air: radon-222 — Part 11: Test method for soil gas with sampling at depth by using active devices RTM1688-2 and RAD 7. The measurements were performed in real conditions where the radon concentration varied following a typical daily variation. Indoor radon c

Beryllium-7 is a natural radionuclide used as a tracer of the stratospheric-tropospheric exchange. Its abundance in the surface air is expected to change as the temperatures in the atmosphere increase. To investigate the temporal trends of the beryllium-7 activity concentrations and temperature, we apply spectral analysis to time series from three sampling sites: Belgrade in Serbia, and Ljubljana and Krško in Slovenia. The sites lie close to the 45 ºN parallel, with Krško approximately 400 km and Ljubljana around 500 km west of Belgrade. Between January 1991 and December 2019, the air filter samples were collected using air samplers; a monthly composite sample was formed and analysed by gamma spectrometry. We use monthly mean temperature records from the European Climate Assessment & Dataset, the Republic Hydrometeorological Service of Serbia for Belgrade, and the Slovenian Environment Agency for the sites in Slovenia. In the spectral analysis decomposition, we look into a term called trend that represents the overall growth (increase or decrease) in the data records. The trend is calculated using a linear fit. All three sites show 1) positive temperature trends, however statistically insignificant (at the 95 % confidence level), and 2) statistically significant beryllium-7 activity concentration trends of 2.26 %/year, 1.13 %/year, and 0.50 %/year in Belgrade, Ljubljana, and Krško, respectively. The results confirm our initial hypothesis–over the 28 investigated years, the beryllium-7 activity concentrations increase in the surface air. On the other hand, the non-significant temperature rise in our records suggests that within our method, the temporal resolution of one month is insufficient for obtaining a statistically significant temperature trend.

The crystal growth rate of lithium germanium-phosphate glass was studied. The glasses have been homogenized using the previously established temperature-time conditions, which make it possible to remove a volatile substances from the glass melt. The AAS was used to determine the chemical content of obtained glass, the differential thermal analysis (DTA), and scanning electron microscope (SEM) were used to reveal the isothermal process of crystal growth, respectively. It has been found that the experimental determined crystal growth rate has a tendency toward of exponentially increase with an increase the temperature.

Radon flux measurements provide information about how much radon rises from the ground toward the atmosphere, thus, they could serve as good predictors of indoor radon concentrations. Although there are many different mapping methods with many different input data, radon flux data are generally missing and are not included for the delineation of radon priority areas (RPA). The aim of this literature review is to investigate to what extent radon flux was used, or could be used, for the delineation of RPAs. Numerous factors influencing radon flux were identified, but quantifying their contribution to radon flux measurement still remains a challenge. Different methods and measuring devices were used for the determination of radon flux, thus it is necessary to identify possible inconsistencies in order to harmonise different radon flux measurements. Due to the complexity of radon flux measurements, only two countries were identified to have performed national surveys on outdoor radon, which were of much smaller scale compared to those on indoor radon. A positive correlation between radon flux and radon quantities, such as radon in soil gas and indoor radon, indicates that radon flux could be used as an input parameter for the estimation of RPA. By reviewing radon flux models, it was concluded that up-to-date modelled radon flux maps have reached excellent spatial resolution and will be further improved, hence, they could serve as an input for the estimation and delineation of RPA.

The paper presents the numerical modelling of concrete-filled steel tube stub columns under axial compression. The nonlinear 3D finite element model for the analysis was developed using ABAQUS software. The modelling, boundary conditions, the constitutive models for steel and concrete and contact interaction between the steel tube and concrete surface are discussed in detail. Three numerical models are proposed and validated using collected experimental data results. Finally, the composite column axial capacity is compared with the Eurocode 4 calculations for composite columns.

Parkinson’s disease (PD) is a second commonest neurodegenerative disorder, followed by the presence of motor symptoms that affect the functioning of a person in the community Technology development and implementation of various diagnostic and assessment procedures can improve the rehabilitation process of this population. IMU sensors have the potential to identify and provide valuable information about motor performances and behavior, as well as the quality of movements. The aim of this paper is to present the possibilities of using Inertial Measurement Units sensors in movement analysis in persons with Parkinson’s disease. Analyzed papers were selected by researching electronic databases: PubMed/MEDLINE, Science Direct, Scindeks, and Google Scholar and published between 2014 and 2020. The analyzed researches have shown that the IMU can be used in the evaluation of motion range and amplitude, repetitive finger taping parameters, characteristics of movements and activities important for everyday living, gait characteristics and parameters, as well as PD related symptoms, such as bradykinesia, tremor, festination, freezing of gait. Sensors, consisted in IMU, also can befused together to provide a 3D picture ofhuman motion.