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Povzetek: Children’s lead exposure in three mining-impacted residential areas (Črna, Mežica and Žerjav) was modelled using the Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK). Site-specific environmental and dietary Pb source values were determined for modelling. For the first time, dietary exposure from both market and local foods was studied in detail. Children (Group 1: 24–36 and Group 2: 36–48 months) geometric mean blood lead levels (BLLs) were predicted and lead uptake from multiple sources was quantified according to the different dietary exposure scenarios. Biomonitoring data were used for validation. Site-specific soil, house dust and local food Pb contents are higher than legislative and background levels, remaining a cause for concern. Drinking tap water concentrations and outdoor air contents were found in acceptable levels. The determined dietary exposures, ranging from 0.7 to 3.3 µg/kg bw/day, were above the benchmark dose level of 0.5 µg/kg bw/day for developmental neurotoxicity set for Pb in children, indicating a health concern. In general, the estimated BLLs matched reasonably well with the observed BLLs in the Črna and Mežica area for both age groups and in the Žerjav area for Group 2. For Group 1, in the Žerjav area, the output of the IEUBK model overestimated the actual BLLs of the children. For both groups, the primary exposure pathway in Žerjav is from soil/dust, ranging from 55.3 to 84.8%. In Črna and Mežica, soil/dust exposure ranged between 24.2 and 57.8% and between 26.4 and 61.7%, respectively, indicating that dietary exposure predominates when local foods are included. The results of our study also suggest that using the IEUBK default diet value would reduce the dietary exposure up to 25.2% in Črna, 24.2% in Mežica and 8.6% in Žerjav. One of the main findings is that a diet containing local foods can be an important source of lead in mining-contaminated areas.
Ključne besede: IEUBK model, blood lead level, soil, house dust, dietary exposure, risk assessment
Objavljeno v DiRROS: 18.09.2025; Ogledov: 327; Prenosov: 115
Celotno besedilo (2,30 MB)

Povzetek: Recently, we have demonstrated that dye-doped soap and smectic bubbles can be used as lasers. Here we investigated smectic bubble lasers for their potential to measure pressure changes in both air and water and as microphones. Smectic bubbles consist of a very thin smectic liquid crystal film. In contrast to ordinary soap bubbles, smectic bubbles are highly stable. When illuminated with a pump laser, they exhibit whispering gallery mode lasing with sharp, regularly spaced peaks in the emission spectrum. The bubbles enable extremely precise measurement of pressure changes based on wavelength shifts of the lasing peaks. We have demonstrated that smectic bubbles can be inflated under water and used as water pressure sensors. Additionally, we have used smectic bubble lasers in air as highly sensitive microphones to detect sound waves across different frequencies with advantages over conventional microphones. Their extremely thin walls result in negligible acoustic impedance. Furthermore, bubble size changes due to pressure variations depend only on bubble volume, eliminating the need for calibration and making performance independent of manufacturing precision or defects. This also leads to a linear amplitude response, and a flat frequency response over a wide range of frequencies. Unlike most microphones, bubble lasers can measure arbitrarily small frequencies down to static pressure, making them promising candidates for acoustic wave detection in various applications.
Ključne besede: smectic bubbles, liquid crystal lasers, smectic liquid crystals, water pressure
Objavljeno v DiRROS: 18.09.2025; Ogledov: 271; Prenosov: 142
Celotno besedilo (2,28 MB)
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Povzetek: Laboratory and field assessments of low-cost sensors (LCS) are essential for ensuring the accuracy of PM2.5 measurements collected by citizens in air quality campaigns. Evaluation of Sensirion SPS30 (LCS SPS30) in controlled laboratory setting showed a coefficient of determination (R2) ranging from 0.81–0.99 and a root mean square error (RMSE) from 0.81–61.72 μg m−3, at average concentration of 21.5 μg m−3. In contrast, co-location assessment at an average concentration of 9 μg m−3 resulted in R2 of 0.5 and a RMSE of 6.82 μg m−3. The results demonstrated that the sensor met micro-environmental monitoring standards (accuracy < 25%) and United States Environmental Protection Agency's performance criteria (RMSE ≤ 7 μg m−3, R2 > 0.7) only at relative humidity (RH) levels below 60%, emphasising its strong sensitivity to RH and the need for RH-dependent data corrections. The observed underestimation or overestimation of PM2.5 readings was primarily attributed to variations in particle composition and concentration. Despite accuracy variations, LCSs can effectively capture spatiotemporal urban air quality patterns and identify pollution hotspots in community monitoring, particularly in low-pollution environments. In a citizen-led PM2.5 monitoring campaign in Maribor, Slovenia, the lowest concentrations were recorded at 15:00 (2.9 μg m−3), while the highest occurred during the morning rush-hour (4.8 μg m−3), likely attributed to the planetary boundary layer’s impact on atmospheric particulate dispersion. Spatial analysis revealed that hotspots clustered near intersections, where vehicle waiting time is the longest.
Ključne besede: particulate matter, low-cost sensor, Sensirion SPS30, citizen science, calibration
Objavljeno v DiRROS: 18.09.2025; Ogledov: 281; Prenosov: 190
Celotno besedilo (3,32 MB)
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Objavljeno v DiRROS: 17.09.2025; Ogledov: 344; Prenosov: 172
Celotno besedilo (1,74 MB)
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Povzetek: This study investigates heat and mass transfer during energetic melt-coolant interactions, focusing on film boiling around a hot melt particle in subcooled convective flow. The considered conditions, free-flow velocities of a few m/s, melt particle temperatures of several thousand K, particle diameters of several tens of a μm, and liquid subcooling of several tens of a K, align with TREPAM experiments (CEA, France). A two-phase computational fluid dynamics framework, based on the Volume of Fluid method, is used. An improved phase-change model is implemented, combining Chen’s explicit formulation of the phase-change intensity factor with the robustness of the conventional Lee model. The approach reduces sensitivity to empirical parameters and enhances phase-change localisation. Additional constraints on the intensity factor ensure numerical stability under extreme thermal conditions relevant to vapour energetic melt-coolant interactions. Simulations of TREPAM experiments demonstrate improved heat flux predictions and enhanced flow dynamics capture. Analysis of the simulated velocity fields reveal secondary flows in the vapour wake, impacting heat and mass transfer and emphasizing the need to resolve vapor-phase flow conditions. To fully validate proposed modifications to phase-change model further numerical and experimental investigation is required, focusing on vapour film morphology and localized heat transfer intensity.
Ključne besede: film boiling, extreme thermal conditions, phase-change modelling, computational fluid dynamics, two-phase flow
Objavljeno v DiRROS: 16.09.2025; Ogledov: 259; Prenosov: 127
Celotno besedilo (4,40 MB)
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