Vinča Institute of Nuclear Sciences
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Radon hazard mapping: usability of environmental predictors including atmospheric radon and radon flux and knowledge transfer between regions (Belgium and Germany)
No full textRadon is a naturally occurring radioactive noble gas. When it accumulates indoors it can be a health hazard. Radon hazard mapping assigns areas to a geogenic radon potential, that reflects the availability and spatial distribution of radon in soil. The possible knowledge transfer from one region to another and the usability of predictors for radon hazard mapping were analysed. Included in the set of predictors were “atmospheric radon” and “radon flux”. A machine learning workflow is outlined using a random forest model to predict the geogenic radon potential in Belgium and Germany. The German data was used as training data and the model performance was evaluated on spatially separated validation data sets in both regions. It was possible to predict the geogenic radon potential for Belgium only using training data from Germany. The evaluation of the model performance on the Belgian validation data set was essential to find this model. The model showing the highest model performance in Belgium differs in main characteristics as number, selection and importance of predictors from the predictive model working best in Germany. The predictions of the geogenic radon potential of these models were accurately in their country but not in the other. The models used different predictors, except the predictor “soil moisture”, which was present in both models. The performance increase for single predictors in Germany is in the range of a few percent, whereas in Belgium a single predictor (“coarse fragments”) can improve the model by over 100%. Among the 30 candidate predictors “radon flux” was present in the best model for Belgium. © The Author(s) 2025
Sintering and characterization of additive‐free B4C/SiCw composites using high‐pressure techniques
No full textDense B4C-based ceramics reinforced with SiC whiskers (SiCw) were successfully fabricated via high-pressure (4 GPa) and high-temperature sintering at 1650°C and 1850°C without any sintering additives. Composites containing 2.5–10 wt.% SiCw were systematically investigated to assess the influence of whisker content and sintering temperature on microstructure, densification, mechanical properties, and thermal diffusivity. Results showed that increasing SiCw content initially improved mechanical performance; however, excessive whisker addition caused a decline in both hardness and fracture toughness due to whisker agglomeration and microstructural inhomogeneities. The composite with 5 wt.% SiCw sintered at 1850°C exhibited the optimal balance, achieving the highest relative density (99.25%), Vickers hardness (30.97 GPa), and fracture toughness (3.24 MPa m1/2). This sample demonstrated the most stable thermal diffusivity at elevated temperatures, with minimal degradation from room temperature up to 1400°C. Conversely, the 10 wt.% SiCw composite sintered at 1650°C showed the highest thermal diffusivity at room temperature (18.5 mm2/s) but suffered from reduced thermal stability at elevated temperatures. These findings underscore the crucial role of SiC whisker content and sintering conditions in tailoring the interplay between mechanical strength and thermal transport in B4C-based ceramics, providing valuable insights for their application in extreme environments
Synthesis, Structural and Magnetic Properties of BiFeO3 Substituted with Ag
No full textHere, we report the hydrothermal synthesis of BFO (bismuth ferrite) and Bi1−xAgxFeO3 (x = 0.01, 0.02) ultrafine nanopowders. The diffraction patterns show that all obtained particles belong to the R3c space group. On top of that, crystal structure prediction has been accomplished using bond valence calculations (BVCs). Several promising perovskite structures have been proposed together with experimentally observed modifications of BFO as a function of silver doping. Magnetization measurements were performed on BFO, both pure and substituted with 1% and 2% of Ag. The addition of Ag in BFO did not affect the Neel temperature, TN = 630 K for all samples; instead, the influence of Ag was observed in the increase in the value and irreversibility of magnetization, which are usual characteristics of weak ferromagnetism. Our calculations based on density functional theory (DFT) are in agreement with the experimental finding of enhanced magnetization upon Ag doping of antiferromagnetic BFO, which is assigned to the perturbation of magnetic-type interactions between Fe atoms by Ag substitutional doping. Additionally, electronic and magnetic properties were studied for all phases predicted by the BVCs study. DFT predicted half-metallicity in the γ phase of BFO, which may be of great interest for further study and potential applications. © 2025 by the authors
Effects of non-isovalent substitution on the structural and magnetic properties of SrFe12-x(CoSn)xO19 solid solutions (x = 0–0.5)
No full textThe complex investigation of influence of chemical substitution magnetoactive ions in solid solutions of SrFe12-x(CoSn)xO19 (x = 0–0.5) synthesized by the sol-gel. The investigation of features of crystal and magnetic structures was carried out with neutron diffraction method with high resolution at room temperature. The reported results demonstrate that dopant concentration influences to the unit cell and microstress parameters as well as magnetic characteristics. The observed decreasing of magnetic moments, coercivity, saturation magnetization, and Curie temperature are attributed to the combined effects of structural distortion, altered superexchange interactions, and the distribution of dopant ions within the crystal lattice
Progress achieved in EURAMET project 21GRD09 MetroPOEM: Metrology for the harmonisation of measurements of environmental pollutants in Europe
No full textThe European Green Deal’s ambition for zero pollution requires development of highly sensitive techniques to detect ultra-low amounts of pollutants and determine their isotope ratios, where mass spectrometry is a key method. The project bridges the traceability gap between activity and mass measurements – particularly estimation of mass bias – and establishes new tools for pollutant tracing. SI-traceable reference materials and measurement procedures are being developed that significantly reduce measurement uncertainty and detection limits, to enable tracking pollution sources by commonly available mass spectrometers. This project supports strategies described by the European Metrology Network on pollution monitoring and the established EMN on radiation protection. Main areas of work are: x Development of low-level radionuclide standards for 90Sr and a series of actinides, x Development of SI traceable high-precision analytical methods for isotope ratio determination of Li, B, Cr, Cd, Ni, Sb, Pb, and U in environmental matrices applicable to single and multi-collector ICP-MS systems.x Generation of two reference materials – seawater and silica – spiked with radionuclides x Production of certified seawater reference material for isotope ratio to validate analytical methods, support proficiency testing, and ensure quality control in future monitoring.x Communication of project outcomes include peer reviewed papers, good practice guides, workshops, conference presentations and more. © The Authors, published by EDP Sciences.Presented at the 22nd International Metrology Congress (CIM2025)
Examination of a hybrid dosimeter: Response to the radiation based influence quantities
No full textTechnological advancements in radiation protection dosimetry are aimed towards enhancing the performance of radiation dose measurement instruments. The performance of a hybrid dosimeter, in terms of radiation-based influence quantities, was evaluated against the IEC 61526:2024 standard for active personal dosimeters. The relative response of the hybrid dosimeter to influence quantities was tested in the range of photon energies from 33.3 keV to 1.25 MeV and angles of incidence from 0° to ±75°, in two perpendicular planes. The response variation with dose, in the range from 30 μSv to 7 Sv, was assessed, along with the influence of dose rate from 70 μSv h−1 to 300 mSv h−1. The dosimeter complies with the standard defined limits of variation from −29 % to +67 % for the energy and angular dependence test and from −13 % to +18 % for the non-linearity test, in the minimum rated range. The energy dependence test was conducted in a wider range of energies than those stated by the standard, which are encountered in medical applications of ionizing radiation. In these irradiation conditions the dosimeter complies with the standard defined limits of variation. Based on the showcased results and the technical specifications of the hybrid dosimeter, it is suitable for diverse applications in medicine, research and industry. © 2025 Elsevier Lt
Sustained EGFR Signaling Expands Otx2+ and Chx10+ Retinal Progenitors in the Postnatal Mouse Retina
No full textThe regenerative potential of the mammalian retina is limited, yet identifying signaling pathways that influence progenitor cell behavior remains an important step toward understanding the mechanisms of retinal development and plasticity. Epidermal Growth Factor Receptor (EGFR) signaling has been implicated in regulating proliferation and differentiation in the central nervous system, but its role in the postnatal retina is less defined. In this study, we employed an ex vivo explant model of the postnatal mouse retina to investigate the effects of sustained Epidermal Growth Factor (EGF) stimulation. Our results demonstrate that EGF extends the proliferative activity of progenitors that are normally quiescent after birth. However, the sustained EGFR activation (10 ng/mL, for 7 days) in the postnatal retina not only promotes EGFR+ progenitor proliferation but also maintains co-expression of Otx2 and Chx10, revealing a distinct progenitor population, suggesting that extended EGF signaling influences lineage allocation. These findings indicate that EGFR activation can modulate both the maintenance and differentiation potential of retinal progenitors in a context-dependent manner. While additional studies are needed to determine whether these progenitors develop into mature, functional neurons, our work provides a framework for future investigations into signaling pathways that may be leveraged to influence retinal development and plasticity
Establishing a working standard for the testing of radiation protection dosimeters
No full textU cilju ispitivanja aktivnih elektronskih dozimetara u kliničkim poljima zračenja, u laboratoriji sa sekundarnim etalonom, sektora za etaloniranje Instituta za nuklearne nauke Vinča, izvršeno je etaloniranje jonizacione komore koja će se koristiti kao tercijarni (radni) etalon. Dodatno, ispitana je energetska zavisnost odziva jonizacione komore u standardnim i nestandardnim kvalitetima zračenja. Dobijeni rezultati analizirani su u odnosu na granice odstupanja definisanih standardom ISO 4037-2:2019. Jonizaciona komora zadovoljava neophodne uslove standarda, te se može smatrati adekvatnim radnim etalonom u celom ispitivanom opsegu energija, osim kvaliteta zračenja N-40.In order to test active electronic dosimeters in clinical radiation fields, the calibration of a spherical ionization chamber was performed in the Secondary Standard Dosimetry Laboratory of the „Vinča“ Institute of Nuclear Sciences, which will represent the tertiary (working) standard. In addition, the performance of the ionization chamber was examined, in terms of its energy dependence in standard and non-standard radiation qualities. The obtained results were analyzed in relation to the limits of deviation defined by the ISO 4037-2:2019 standard. The ionization chamber meets the necessary conditions and can be used as a standard instrument in the whole range of energies that was investigated, except for radiation quality N-40.XXXIII симпозијум ДЗЗСЦГ [Друштва за заштиту од зрачења Србије и Црне Горе] : 1-3. октобар 2025. године
Survey meter performance evaluation according to the national regulation on radiation protection dosimeters
No full textPravilnikom o dozimetrima je u oblast zaštite od zračenja uvedena zakonska regulativa za aktivne elektronske dozimetre, u smislu njihovog periodičnog etaloniranja i overavanja. Takođe, Pravilnikom je poboljšana dozimetrijska praksa u oblasti zaštite od zračenja usled postavljanja kriterijuma prihvatljivosti za aktivne elektronske dozimetre u vidu najveće dozvoljene greške. Izvršeno je ispitivanje performansi pet najčešće korišćenih modela monitora zračenja u širokom opsegu jačina ambijentalnog ekvivalenta doze, kao i u širokom opsegu energija od N-40 (33,3 keV) do S-Co (1,25 MeV). Ispitivani dozimetri su overeni, pošto su pokazali zadovoljavajuće dozimetrijske karakteristike.Through the national regulation on radiation protection dosimeters, a legal framework was established, enforcing their periodic calibration and verification. By introducing the verification acceptability criteria, defined by the national regulation document, and expressed in terms of maximum permissible error, the radiation protection dosimetry practice was improved. Performance assessment of five most commonly used survey meters was done in a wide range of ambient dose equivalent rate and a wide photon energy range from N-40 (33.3 keV) to S-Co (1.25 MeV). Examined dosimeters were successfully verified, displaying satisfactory dosimetric properties.XXXIII симпозијум ДЗЗСЦГ [Друштва за заштиту од зрачења Србије и Црне Горе] : 1-3. октобар 2025. године
Raman spectroscopy studies of silver nanoparticles in HeLa cells
No full text7th EuChemS Inorganic Chemistry Conference - EICC7 ; 7-11 September 2025, Belgrade