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This work highlights the potential for the synthesis of new PtSnZn catalysts with enhanced efficiency and durability for methanol oxidation reaction (MOR) in low-temperature fuel cells. In this research, PtZn and PtSnZn nanoparticles deposited on high surface area Vulcan XC-72R Carbon support were created by a microwave-assisted polyol method. The electrochemical performances of synthesized catalysts were analyzed by cyclic voltammetry and by the electrooxidation of adsorbed CO and the chronoamperometric method. The physicochemical properties of obtained catalysts were characterized by transmission electron microscopy (TEM), thermogravimetric (TGA) analysis, energy dispersive spectroscopy (EDS) and by X-ray diffraction (XRD). The obtained findings showed the successful synthesis of platinum-based catalysts. It was established that PtSnZn/C and PtZn/C catalysts have high electrocatalytic performance in methanol oxidation reactions. Catalysts stability tests were obtained by chronoamperometry. Stability tests also confirmed decreased poisoning and indicated improved stability and better tolerance to CO-like intermediate species. According to activity and stability measurements, the PtSnZn/C catalyst possesses the best electrochemical properties for the methanol oxidation reaction. The observed great electrocatalytic activity in the methanol oxidation reaction of synthesized catalysts can be attributed to the beneficial effects of microwave synthesis and the well-balanced addition of alloying metals in PtSnZn/C catalysts.

We report on the aerosol generation of ligand-free silver iodobismuthate (Ag-Bi-I) nanoparticles (NPs) and on in situ investigation of their electronic structure using synchrotron radiation soft X-ray aerosol photoelectron spectroscopy (XAPS). The structural and morphological characterizations revealed the aerosol to be composed of spherical rudorffite Ag3BiI6 particles, approximately 100 nm in size. The XAPS showed well-resolved signals from all expected elements (Ag, Bi, and I) and allowed estimation of the NP work function to be about 4.5 eV. The ionization energy of Ag3BiI6 NPs was determined to be 6.1 eV that is in good agreement with our calculations based on a hybrid functional approach. The presented method of production of Ag3BiI6 aerosol can prove beneficial for the future development of Ag-Bi-I-based photovoltaic materials, since it allows the deposition of Ag-Bi-I particles on large surface areas of arbitrary shape and roughness.

This analysis of 238 U, 226 Ra and210Pb trans fer fac tors from the soil to the leaves of dif fer ent na tive broadleaf trees at sites pre viously mod ified by ura nium pres ence and at the site of back-ground ra dio ac tiv ity lev els, was con ducted using data from a few available stud ies from the lit er ature. The broadleaf tree species Quercus ilex, Quercus suber, Euca lyp tus camaldulensis, Quercus pyrenaica, Quercus ilex rotundifolia, Populus sp. and Eu calyptus botryoides Sm. at the affected sites and Tilia spp. and Aesculus hippocastanum L. at the back ground site were in cluded in the study regardless of the de cid uous or evergreen or igins of the leaves. In the papers cited here, data about ba sic soil parameters: pH, to tal Ca [gkg–1], sand [%], and silt + clay [%] fractions were also available. All the col lected data of ac tiv ity con cen tra tion [Bqkg–1] dry weight in the soil (n=14) which was in the range: 22-6606 for238U, 38-7700 for226Ra, and 37-7500 for210Pb, and the tree leaves in the range: 2.7-137.6 for238U (n=10), 2.6-134.2 for226Ra (n=14), and 27-77.2 for210Pb (n=14), in di cated that it was nor mally dis trib uted af ter log-transformation. The present study was conducted under the hypothesis that biological dif fer ences between the examined broadleaf tree species have a lesser in flu ence on the trans fer factors of the investigated radionuclides from soil to tree leaves compared to the impact of the soil parameters and radionuclides ac tiv ity con cen tra tions in the soil. Con sequently, it was ex-amined whether 238 U, 226 Ra, and210Pb soil-to-leaves trans fer fac tor val ues for av erage broadleaf spe cies could be predicted sta tis ti cally in the first ap prox imation based on their ac-tiv ity con cen tra tion in the soil and at least one basic soil pa ram eter using mul ti ple lin ear re-gression. © 2022, Vinca Inst Nuclear Sci. All rights reserved.

Two samples collected from the phosphogypsum deposits of the chemical products industry Elixir Prahovo (Serbia) were subjected to a recrystallization experiment performed over several repeated cycles. In these tests, phosphogypsum was separated into recrystallized (purified) gypsum, insoluble residue and supernatant. Both raw phosphogypsum and recrystallized gypsum were examined using inductively coupled plasma optical emission spectrometry, X-ray diffraction and scanning electron microscopy with energy-dispersive spectrometry. The activity concentrations of 238U, 235U, 226Ra, 210Pb, 232Th and 40K were investigated using γ-ray spectrometry. Based on the activity concentration results, a number of radiometric parameters were calculated for the original and recrystallized phosphogypsum (i.e. radium equivalent activity, γ indices for construction materials, α index and external and internal hazard indices). Raw phosphogypsum samples showed greater mean activity concentration levels of 238U and 226Ra than the international recommended limits, while the recrystallized gypsum demonstrated notably lower activity concentrations for these two isotopes. The activity concentration of 226Ra in recrystallized gypsum is ~6 times lower than in raw phosphogypsum. Therefore, recrystallized gypsum does not present a radiation hazard when used as a building material, while raw phosphogypsum meets the requirements only for road construction materials.

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.

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.

The aim of this work was to identify and quantify fatty acids presented in pollen samples collected from six different Serbian maize hybrids by GC capillary method. Due to great importance of fatty acids as food component potential nutritional value of maize pollen as food supplement in human diet was determined. It has been shown that pollen is a great source of different fatty acids, especially unsaturated fatty acids. In total, twenty eight fatty acids were quantify - the most abundant saturated FAs were palmitic and henicosanoic acid; the most prevalent monounsaturated FAs were oleic, elaidic and cis -10-heptadecenoic acid. Linoleic and cis -11,14-eicosadienoic acid were the most abundant polyunsaturated fatty acid. Also, it was found that FAs composition was significantly influenced by the type of maize hybrids. According to nutritional recommendations, four of six pollen samples had good nutritional quality with unsaturated/saturated fatty acids ratio higher than 1.6, but there is unsatisfied distribution of ω-6 and ω-3 fatty acids as the most important type of unsaturated fatty acids.

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 (

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 is a preliminary study of the depth distribution of 137Cs radionuclides in cultivated anthrosol soil of a 15-year old peach tree plantation at the experimental field “Radmilovac” near Belgrade. Before planting, the soil was ploughed at the depth of 1 m. The soil had not been annually ploughed, irrigated and treated with mineral fertilizers for three years before sampling. Activity concentration for 137Cs ranged from 1.8 Bq kg-1 to 35 Bq kg-1. Along the soil depth it varied highly, reaching as high a total variation coefficient as 83 %. Radiocaesium distribution patterns depended on the extent of soil mixing in the plough layer, as it was mechanically transferred from the surface to the lower soil layers during cultivation. 137Cs was associated with humus content and fixation to clay fractions in the soil. Our results single out soil’s hygroscopic water as a valuable parameter for 137Cs behaviour that could be used commonly if the measurement is standardised., Ovo je preliminarno istraživanje dubinske raspodjele radionuklida 137Cs u kultiviranome zemljištu tipa Antrosol 15 godina starog voćnjaka pod zasadom breskvi koje pripada oglednom poljoprivrednom dobru “Radmilovac” u blizini Beograda. Dubokim oranjem do dubine od 1 m zemljište je pripremljeno za postavljanje zasada breskvi. Tri godine prije uzorkovanja zemljišta prekinuta je obrada voćnjaka odnosno godišnje oranje (do 40 cm dubine), navodnjavanje i unos mineralnoga gnojiva. Koncentracija aktivnosti 137Cs kretala se od 1,8 Bq kg-1 do 35 Bq kg-1 i bitno varirala s povećanjem dubine zemljišta te dostigla ukupni koeficijent varijacije od 83 %. Obrasci raspodjele radiocezija po dubini zavisili su od stupnja obrade zemljišta u prethodnom razdoblju, s obzirom na to da je mehanička manipulacija zemljišta dovela do njegove prisutnosti i u nižim slojevima. 137Cs izravno je korelirao sa sadržajem humusa i bio je fiksiran za glinovitu frakciju zemljišta, što upućuje na njegovu povezanost s česticama zemlje. Unatoč tome što se sadržaj higroskopske vlage u zemljištu pokazao korisnim parametrom za opis ponašanja cezija, za njezino određivanje još uvijek nije utvrđena standardna metoda mjerenja.

This is a preliminary study of the depth distribution of 137Cs radionuclides in cultivated anthrosol soil of a 15-year old peach tree plantation at the experimental field “Radmilovac” near Belgrade. Before planting, the soil was ploughed at the depth of 1 m. The soil had not been annually ploughed, irrigated and treated with mineral fertilizers for three years before sampling. Activity concentration for 137Cs ranged from 1.8 Bq kg-1 to 35 Bq kg-1. Along the soil depth it varied highly, reaching as high a total variation coefficient as 83 %. Radiocaesium distribution patterns depended on the extent of soil mixing in the plough layer, as it was mechanically transferred from the surface to the lower soil layers during cultivation. 137Cs was associated with humus content and fixation to clay fractions in the soil. Our results single out soil’s hygroscopic water as a valuable parameter for 137Cs behaviour that could be used commonly if the measurement is standardised.

Distribution of natural gamma-emitting radionuclides 238U and 40K were determined in the soil profiles from the peach-trees field on experimental farm Radmilovac, southeast Belgrade. Internal soil morphology has been changed in 1992. when soil rigosol type with deep Ap-horizon (0-80 cm) has been formed by special treatment of parent soil, chernozem type. Gamma-spectrometry method is applied in measurement of radionuclide activities in soil samples by using hyperpure coaxial gamma-ray detector, Canberra type. Investigation results has been shown that the natural activity contents obtained in the experiment are within the range of normal BACKGROUND: activity according to UNSCEAR (2000) and that radionuclide activity decreased in the plant root zone. Distribucija prirodnih radionuklida gama-emitera 238U i 40K je određena u profilima zemljišta sakupljenih sa voćnjaka pod zasadom breskvi na Oglednom školskom poljoprivrednom dobru 'Radmilovac', Poljoprivrednog fakulteta, Beograd-Zemun. Unutrašnja morfologija zemljišta je izmenjena 1992. godine kada je zemljište rigosol tipa sa dubokim Ap-horizontom (0-80 cm) formirano rigolovanjem osnovnog zemljišta černozem tipa. Aktivnost radionuklida u uzorcima zemljišta određena je metodom gama-spektrometrije korišćenjem koaksijalnog HPGe-detektora (Canberra). Rezultati ispitivanja su pokazala da je eksperimentalno određena prirodna aktivnost u granicama normalne osnovne aktivnosti preporučene od strane UNSCEAR (2000) i da aktivnost radionuklida opada u zoni korenovog sistema.

Activity concentration of natural radionuclides and Cs-137 were studied in leaves of the deciduous trees. In the spring and autumn season, leaves were collected in the area of normal BACKGROUND: radiation levels represented by city parks in a multi-year period (2002-2012). Measurements by means of gamma-ray spectrometry showed Ra-226 and (210)pb seasonal accumulation in leaves, while U-238 and U-235 could be detected only in autumn. Difference between seasons was not found significant for K-40 and Cs-137. The study of radionuclides transfer factors was conducted by analyzing its relationships with basic soil properties at the beginning and the end of the vegetation period.