Vinča Institute of Nuclear Sciences
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Source-specific probabilistic exposure to PM2.5-bound trace elements in a school environment
No full textSource-specific risks of fine particulate matter (PM2.5)-bound trace elements to student's health in a school located in an urban area were evaluated. The concentrations of the 29 elements in PM2.5 were analyzed indoors and outdoors at the school. PM2.5 concentrations ranged from 5.33 to 47.5 μg/m³ indoors to 8.22–83.1 μg/m³ outdoors. Besides Ca and Fe being the most abundant elements analyzed in PM2.5 both indoors and outdoors, the levels of Zn, Cr, Pb, Cu, Mn, and Ni were significant. The indoor/outdoor ratio of PM2.5 for most elements was below one. Positive matrix factorization (PMF) identified six primary sources with different loadings of PM2.5-bound toxic elements, whereas traffic and resuspended dust were the predominant element sources. The health risk assessment results indicated that the risks for students due to inhalation exposure to elements were within the safety threshold. Nickel, Cr, and Mn dominantly contributed to non-carcinogenic risks, whereas higher cancer risks were associated with Cr and, to a lesser extent, with As. The hazard index and total carcinogenic risk were within acceptable levels. The Monte Carlo simulations implied that vehicle-originated elements contributed the most to non-carcinogenic and carcinogenic health risks. These findings underscore the need to address air pollution in urban school environments more precisely, focusing on protecting young students from exposure to PM2.5-bound toxic elements
Inertial Memory Effects in Molecular Transport Across Nanoporous Membranes
No full textNanoporous membranes are heterogeneous structures, with heterogeneity manifesting at the microscale. In examining particle transport through such media, it has been observed that this transport deviates from classical diffusion, as described by Fick’s second law. Moreover, the classical model is physically unsustainable, as it is non-causal and predicts an infinite speed of concentration perturbation propagation through a substantial medium. In this work, we have derived two causal models as extensions of Fick’s second law, where causality is linked to the effects of inertial memory in the nanoporous membrane. The results of the derived models have been compared with each other and with those obtained from the classical model. It has been demonstrated that both causal models, one with exponentially fading inertial memory and the other with power-law fading memory, predict that the concentration perturbation propagates as a damped wave, leading to an increased time required for the cumulative amount of molecules passing through the membrane to reach a steady state compared to the classical model. The power-law fading memory model predicts a longer time required to achieve a stationary state. These findings have significant implications for understanding cell physiology, developing drug delivery systems, and designing nanoporous membranes for various applications
Microstructural Analysis and Radiological Characterization of Alkali-Activated Materials Based on Aluminosilicate Waste and Metakaolin
No full textThe formation of an aluminosilicate gel structure made of alkali-activated materials (AAMs) was conducted through an alkali-activation reaction of the solid precursors (fly ash, metakaolin, and wood ash). Fly and wood ash are by-products of the burning process of coal and wood, respectively. Alkali-activated materials of aluminosilicate origin, made from the different ashes, fly and wood, are very attractive research targets and can be applied in various technological fields due to their thermal stability, resistance to thermal shock, high porosity, high sustainability, and finally, low energy loss during production. In this paper, we evaluate physico-chemical properties, microstructure, and radiological environmental impacts when wastes that contain elevated levels of naturally occurring radionuclides (NORs) such as fly ash and wood ash are made into “green cements” such as AAMs. The determination of radionuclide content was performed by means of gamma-ray spectrometry. Results showed that the AAMs have a lower value in the activity concentration of radionuclides than raw materials. The external absorbed gamma dose rate was 74.7–107.3 nGy/h, and the external radiation hazard index values were in range of 0.445–0.628 Bq/kg. The results of the activity concentration measurements for alkali-activated materials indicate the potential of their safe application in building construction. In terms of the structural characterizations, the obtained alkali-activated materials were examined using XRD, DRIFT, FESEM, and TEM analyses
Coarse to Fine: The Role of Severe Plastic Deformation in Advancing Titanium-Based Medical Implants - A Comprehensive Review
No full textThis paper describes severe plastic deformation (SPD) procedures, which are utilized to form an ultrafine-grained structure in metallic biomaterials. During the SPD process, a solid material sample is subjected to very high loads without a significant change in sample dimensions. In the present work, the highpressure torsion (HPT) process, as one of the SPD techniques, which achieves a high degree of deformation and ensures refinement of the microstructure, will be discussed in more detail. Considering that grain size control is accepted as a method to obtain materials with desired characteristics, an overview of the properties of ultrafinegrained titanium-based biomaterials to be used in medicine is given. Moreover, particular attention is dedicated to the influences of HPT process parameters, primarily hydrostatic pressure, and number of revolutions during torsion, on the grain size and physical and mechanical characteristics (modulus of elasticity, microhardness, and tensile properties), corrosion resistance, and biocompatibility of the titanium-based biomaterials. A review of the literature indicates that titanium-based materials obtained by the SPD process show improved mechanical and physical properties without losing biocompatibility and corrosion resistance, which suggests that these methods of obtaining implants are something that should be further developed in the futur
Dynamics of Photoinduced Charge Carrier and Photothermal Effect in Pulse-Illuminated Narrow Gap and Moderate Doped Semiconductors
No full textWhen a sample of semiconducting material is illuminated by monochromatic light, in which the photon energy is higher than the energy gap of the semiconductor, part of the absorbed electromagnetic energy is spent on the generation of pairs of quasi-free charge carriers that are bound by Coulomb attraction. Photo-generated pairs diffuse through the material as a whole according to the density gradients established, carrying part of the excitation energy and charge through the semiconducting sample. This energy is indirectly transformed into heat, where the excess negatively charged electron recombines with a positively charged hole and causes additional local heating of the lattice. The dynamic of the photoexcited charge carrier is described by a non-linear partial differential equation of ambipolar diffusion. In moderate doped semiconductors with a low-level injection of charge carriers, ambipolar transport can be reduced to the linear parabolic partial differential equation for the transport of minority carriers. In this paper, we calculated the spectral function of the photoinduced charge carrier distribution based on an approximation of low-level injection. Using the calculated distribution and inverse Laplace transform, the dynamics of recombination photoinduced heat sources at the surfaces of semiconducting samples were studied for pulse optical excitations of very short and very long durations. It was shown that the photoexcited charge carriers affect semiconductor heating depending on the pulse duration, velocity of surface recombination, lifetime of charge carriers, and their diffusion coefficient. © 2025 by the authors
W-state generation and verification in linearly coupled waveguide arrays
No full textW states are maximally entangled states with excellent robustness to loss. They have been studied in ion, photon and waveguide-mode bases, however the entanglement verification has remained challenging. Here, we theoretically study W-state generation by the quantum walk of a single photon through a linearly coupled waveguide array (WGA) that supports self-imaging of light. We design W states in symmetric and asymmetric arrays with even and odd number of waveguides. Bipartite entanglement is formally proven using the von Neumann entropy of the reduced density matrix. We further use the self-imaging to construct an entanglement witness based on the exclusion principle. A key to verification is the interferometer which extends the length of a W-state generator to the revival length where the photon is fully recombined into a single waveguide mode. In addition, W-state coherence is proven by numerically demonstrating the far-field interference. The sensitivities of the proposed W-state generation and verification protocols to the fabrication tolerances are numerically evaluated in glass, silicon nitride and silicon-on-insulator WGAs, indicating the feasibility of their realisation by high-precision e-beam lithography and laser writing
Assessment of the Effectiveness of Commercial Enzymes for Polyurethane Biodegradation
No full textPolyurethanes (PUs) are widely used in various industries, but their durability raises significant disposal and environmental concerns. Enzymatic degradation offers a sustainable approach to address these challenges by providing a pathway for PU waste management. This study investigates the enzymatic degradation pathways of PU structures of varying complexity using lipase, protease, peroxidase, and combinations of these enzymes. The focus is on elucidating the mechanisms of degradation and structural changes through structure characterization and thermal analysis techniques. Complementing the experimental analyses, a comprehensive computational study evaluates the interactions between the enzyme and the PU structures. The computational results are then compared with the experimental findings, providing a thorough understanding of these interactions. The findings underscore the potential of enzymatic degradation of PU and the effectiveness of enzyme mixtures, especially the combination of lipase and peroxidase, as well as the synergistic action of all three enzymes. Peroxidase emerges as a highly efficient catalyst for PU degradation, complementing the esterase and amidase enzymes previously studied in this context. The key amino acids that participate in the binding of the enzymes to PUs are also highlighted. This research underscores the promise of enzymatic approaches for environmentally friendly PU recycling
Low-Cost and Eco-Friendly method for activating carbon felt using hypochlorite for electrochemical applications
No full textPristine carbon felt is activated and functionalized through a cost-effective, eco-friendly method by immersion in a commercial 5 wt% hypochlorite solution. Electrochemical analyses, including cyclic voltammetry, galvanostatic charge–discharge tests, capacitance, and impedance measurements at 1 Hz, reveal that the activated carbon felt exhibits a twenty-fold enhancement in performance compared to its pristine counterpart. Pristine and activated carbon felt are characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, contact angle measurement, and water uptake tests confirming the significant changes in material properties. To further validate the activation process, polypyrrole is galvanostatically electrodeposited on both pristine and activated carbon felts, with their electrochemical behaviors serving as a model system. The findings indicate a substantial improvement of activated carbon felt, with fourth times increase in capacity, highlighting the potential for advanced applications
Time-Domain Raman Spectroscopy: An Emerging Technique in Space Exploration?
No full textThe potential of time-domain Raman spectroscopy in space exploration is discussed. This work is motivated by the emergence of robust, space-qualified femtosecond lasers and by the fact that time-domain detection allows the design of very compact instruments. As is shown, time-domain Raman spectroscopy gives access to the same fingerprint spectrum of minerals as conventional Raman spectroscopy, while avoiding problems such as fluorescence or ambient light backgrounds. © 2025 The Author(s). Journal of Raman Spectroscopy published by John Wiley & Sons Ltd
Impact of structure, crystallinity, and irradiation modality on post-irradiation free radical evolution in PEs
No full textPolyethylene (PE) has many advantages as a polymeric material for biomedical applications, including single-use (SU) medical ones. Depending on the type of PE, its applications vary from single-use medical device packaging to implants for joint prostheses and custom-made artificial bones. The need to sterilize these products has led to more intensive use of different modalities of high-energy radiation (gamma, electron beam (EB), and X-ray) due to heat input limitations and EtO toxicity. In this paper, we investigate the effects of gamma and electron beam (EB) radiation on various PE types (LDPE, LLDPE, HMWPE, UHMWPE, and HDPE), focusing on how the initial structure and crystallinity influence postirradiation behavior and the evolution of long-lived free radicals. Long-lived free radicals were monitored for up to six months, with their evolution correlated to the initial structure and crystallinity. Chain scission, oxidative degradation, and decline in properties caused by long-lived free radicals can continue long after irradiation, significantly impacting performance during storage and even failure of medical devices during exploitation. This article establishes a good correlation between crystallinity and post-irradiation evolution of long-lived free radicals, with limited consideration of other structural features and the presence of additives