1. The effect of firing conditions on the characteristics of thick-film resistors for temperature sensorsBarbara Repič, Darko Belavič, Danjela Kuščer, 2024, izvirni znanstveni članek Povzetek: : An integrated miniature electrochemical sensor (ES) that offers rapid, sensitive, and selective detection of chemical and biological contaminants in a variety of samples requires temperature control to work accurately. To address this, one approach is to locate temperature sensor (TS) next to the ES components. However, this integration poses a challenge as different firing processes are required for the sensor components and the TS. Commercially available thick-film materials for the realisation of TS are designed for screen printing on alumina and firing in air at 850 °C for 10 minutes. However, a key component of an ES, a carbon-based working electrode, must be fired in an oxygen-lean atmosphere. In this study, we investigated the influence of the firing atmosphere, i.e., air and argon, on the characteristics of thick-film resistors, including thickness, roughness, phase composition, resistivity, and temperature dependence. For the study, we used two commercially available thick-film pastes, NTC2114 and NTC2113, as TS with nominal sheet resistivities of 10 kΩ/sq and 1 kΩ/sq at 25 °C, respectively. Using X-ray powder diffraction analyses, we detected RuO2 and spinel phases in the samples heated at 850 °C in air. However, when the samples were fired in argon, we detect metallic ruthenium and alloys. As a result of these changes, the resistivity of the NTC2114 and NTC2113 increased significantly. However, despite these changes, the relative resistance and the coefficient of temperature sensitivity did not vary significantly, indicating the suitability of these materials as TS. These findings have important implications for the future integration of TS into various screen-printed ES systems, fostering the design and development of systems with enhanced accuracy and reliability in temperature measurements.
Ključne besede: NTC, thick film, screen printing, temperature sensors
Objavljeno v DiRROS: 23.10.2025; Ogledov: 261; Prenosov: 114
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3. Physical activity and screen time in preschool children in CroatiaVesna Brumnić, Sanja Šalaj, Rado Pišot, 2025, izvirni znanstveni članek Povzetek: This research investigates how disparities in physical activity and screen time among preschoolers can be influenced by parental education and involvement, as well as the involvement of the extended family in child-rearing. The study involved 231 parents who provided information about their children from the three (out of four) re-gions in Croatia. The analysis revealed statistically significant differences in children’s screen time based on the parents’ educational level (p<0.000) and involvement in joint physical activity (p<0.000). No differences were found in the children’s screen time or physical activity depending on the involvement of extended family members (grandpar-ents). Less screen time does not automatically mean higher levels of physical activity in preschool children. It is essential to determine the factors that influence physical activ-ity in preschool children and the time they spend in front of screens
Ključne besede: preschool children, family, screen time
Objavljeno v DiRROS: 09.09.2025; Ogledov: 370; Prenosov: 178
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4. Synergistic effect of screen-printed Al(OH)3 nanoparticles and phosphorylated cellulose nanofibrils on the thermophysiological comfort and high-intensive heat protection properties of flame-retardant fabricTjaša Kolar, Jelka Geršak, Nataša Knez, Vanja Kokol, 2022, izvirni znanstveni članek Povzetek: Al(OH)3 nanoparticles (ATH NPs) and phosphorylated cellulose nanofibrils (PCNFs) were used as user-friendly and comfortable coating components on flame-retardant fabric to improve its thermophysiological comfort and high-intensive heat protection properties. The effect of the PCNF imprinting and its attachment after the post-printing of a hydrophobic polyacrylate (AP) on the same (back side) or the other (front) side of the fabric, with and without the addition of ATH NPs, was considered, to maintain the front side (facing the wearer) as hydrophilic while keeping the back side (facing the outside) hydrophobic. The amount of coatings applied and their patterning were studied, varied with the ATH NPs’ concentration (1.7, 3.3 and 6.7 wt%) and screen mesh size used (60 and 135), based on the coating’ mass, fabric’s air permeability, thickness and microstructure. The reduced moisture build-up (55%), increased the water vapour (13%) and heat (12%) transfer from the skin, were assessed by applying PCNF under the AP, being more pronounced in the case of using a 135 mesh-sized screen, given the smaller, more densely distributed, thinner and imprinted pattern coatings. These effects were further improved by the addition of nanoporous ATH NPs, which allowed more homogeneous spreading of the moisture and its faster transport. Such a treatment also shifted the fabric’s degradation temperature towards higher values (up to 15°C), retained up to 30% of high-heat flux (21 kW/m2), prolonged the time to ignition by 11 s and reduced the total heat released by up to 60%, thereby providing better protection when exposed to the heat, due to the presence of the phosphorous (PCNF) promoted generation of an Al2O3 char acting as a barrier layer, while also reducing the production of heat and generation of smoke by 75%.
Ključne besede: flame-retardant textile, Al(OH)3 nanoparticles, phosphorylated cellulose nanofibrils, screen-printing, thermophysiological comfort, heat protection
Objavljeno v DiRROS: 28.04.2023; Ogledov: 1438; Prenosov: 744
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