771. An advanced miniature fluidic system in multilayer ceramic technology with precise temperature and flow control for in situ pollution monitoringDanjela Kuščer, Barbara Repič, Kostja Makarovič, Maksimiljan Dekleva, Gregor Marolt, Helena Prosen, Darko Belavič, 2024, izvirni znanstveni članek Povzetek: Rapid, on-site, water-quality monitoring is necessary to prevent and remediate environmental pollution. This study aims to develop a miniature, portable, fluidic system (MFS) designed for the easy insertion of disposable, screen-printed electrodes (SPEs) and the measurement of an electrochemical response (EC) under controlled temperature and flow conditions. The three-dimensional MFS, realised in low-temperature, cofired ceramic and multilayer ceramic technology, consist of three distinct cavities, each with separate inlet and outlet channels. These channels are designed to maintain an equivalent flow rate across all three cavities. The MFS allows simultaneous measurements at three measuring sites, temperature control of the fluid from room temperature to 125 °C via integrated heaters and temperature sensors, and flow regulation up to 20 mL/min via an external fluid pump. The EC values obtained from the SPEs in a standard solution of potassium ferrocyanide/potassium ferricyanide at room temperature and under stagnant conditions were consistent with measurements conducted in the MFS, droplet and conventional electrochemical cells, confirming the accuracy and reliability of the MFS. The EC response was confirmed in the MFS under flow conditions of 4 mL/min and temperatures of 25 °C, 35 °C, and 45 °C. This shows that multilayer ceramic technology enables the fabrication of a miniature, three-dimensional MFS with integrated fluidic and electronic components that provide reliable and accurate electrochemical measurements using a commercial SPE under controlled flow and temperature conditions.
Objavljeno v DiRROS: 23.10.2025; Ogledov: 212; Prenosov: 34
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775. Thresholds for the biased Maker-Breaker domination gamesBoštjan Brešar, Csilla Bujtás, Pakanun Dokyeesun, Tanja Dravec, 2025, izvirni znanstveni članek Povzetek: In the $(a,b)$-biased Maker-Breaker domination game, two players alternately select unplayed vertices in a graph $G$ such that Dominator selects $a$ and Staller selects $b$ vertices per move. Dominator wins if the vertices he selected during the game form a dominating set of $G$, while Staller wins if she can prevent Dominator from achieving this goal. Given a positive integer $b$, Dominator's threshold, ${\rm a}_b$, is the minimum $a$ such that Dominator wins the $(a,b)$-biased game on $G$ when he starts the game. Similarly, ${\rm a}'_b$ denotes the minimum $a$ such that Dominator wins when Staller starts the $(a,b)$-biased game. Staller's thresholds, ${\rm b}_a$ and ${\rm b}'_a$, are defined analogously. It is proved that Staller wins the $(k-1,k)$-biased games in a graph $G$ if its order is sufficiently large with respect to a function of $k$ and the maximum degree of $G$. Along the way, the $\ell$-local domination number of a graph is introduced. This new parameter is proved to bound Dominator's thresholds ${\rm a}_\ell$ and ${\rm a}_\ell'$ from above. As a consequence, ${\rm a}_1'(G)\le 2$ holds for every claw-free graph $G$. More specific results are obtained for thresholds in line graphs and Cartesian grids. Based on the concept of $[1,k]$-factor of a graph $G$, we introduce the star partition width $\sigma(G)$ of $G$, and prove that ${\rm a}_1'(G)\le \sigma(G)$ holds for any nontrivial graph $G$, while ${\rm a}_1'(G)=\sigma(G)$ if $G$ is a tree.
Ključne besede: Maker-Breaker domination game, biased Maker-Breaker game, trees, line graph, grid
Objavljeno v DiRROS: 23.10.2025; Ogledov: 170; Prenosov: 107
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777. Poročilo o stanju kmetijstva, živilstva, gozdarstva in ribištva : 2024Matej Bedrač, Sara Bele, Ajda Bleiweis, Jure Brečko, Ana Hiti Dvoršak, Maja Kožar, Ben Moljk, Špela Pucihar, Tanja Travnikar, Barbara Zagorc, 2025, končno poročilo o rezultatih raziskav Ključne besede: kmetijstvo, gozdarstvo, živilstvo, trgi, statistika, kmetijska ekonomika, kmetijska politika, Slovenija
Objavljeno v DiRROS: 23.10.2025; Ogledov: 245; Prenosov: 109
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778. 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: 190; Prenosov: 93
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780. Carbon-based thick films for electrochemical detection of neonicotinoid insecticidesBarbara Repič, Gregor Marolt, Danjela Kuščer, 2025, izvirni znanstveni članek Povzetek: Neonicotinoids (NNIs) are water-soluble, toxic, widespread-used systemic insecticides commonly found in the environment. Integrated electrochemical sensors enable the rapid on-site detection of NNIs in aqueous samples by analysing the reduction of the NNI's nitro functional group on the working electrode. We have investigated graphite (G), glassy carbon (GC) and carbon black (CB) thick films as working electrodes for the electrochemical detection of the NNI imidacloprid (IMD). Up to 35-μm-thick films of G, GC and CB on alumina were prepared by screen printing and subsequent firing at 850 °C in argon. G had the largest grain size, the roughest surface, and the lowest sheet resistance of 6.9 Ω/sq. GC and CB had a smoother surface, while their sheet resistances were up to 27 Ω/sq. All three films showed a reversible response to the Fe(CN)63−/4− redox probe with G having the highest electrochemically active surface area and the highest heterogeneous electron transfer rate constant. In the IMD solution with neutral pH, G, GC and CB exhibited characteristic reduction peak at −1.1 V and a re-oxidation peak at +0.2 V. An additional adsorption cathodic peak was observed with CB, indicating a significantly higher affinity of CB for IMD adsorption. With LODs under 1 μM, the G, GC and CB pristine thick films exhibiting great potential for the sensitive detection of IMD
Objavljeno v DiRROS: 23.10.2025; Ogledov: 171; Prenosov: 67
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