1. Large high-temperature piezoelectric response of lead-free ▫$BiFeO_3–BaTiO_3$▫ originating from relaxor disorderAntonio Iacomini, Janina Roknić, Issa Sidibe, Marco Scavini, Mojca Otoničar, Hana Uršič Nemevšek, Tadej Rojac, 2025, izvirni znanstveni članek Povzetek: To date, no piezoelectric material system has been developed that would match the piezoelectric performance of the group of lead-based relaxor ferroelectrics, such as Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT). In the quest to f ind alternatives, continuous efforts have been made to understand the complex microscopic origins leading to the large macroscopic piezoelectric response of PMN–PT and similar lead-based perovskites with relaxor characteristics. Despite significant advances, it is still unclear whether those concepts can be efficiently used to develop lead-free relaxor ferroelectric alternatives. Here, a large piezoelectric response of BiFeO3–BaTiO3 (BFO–BTO) ceramics is reported, characterized by a d33 coefficient of 1200 pmV−1 measured at 325 °C, 1 kV cm−1 of driving field and 90 Hz of field frequency. While composed of multiple contributions, the large response is found to be dominated by a strongly nonlinear and hysteretic process, likely associated with the dynamics of hierarchically arranged nanodomain walls, thus resembling the mechanisms operating in lead-based relaxor materials. Although the response is triggered upon elevated thermal energy, the results provide valuable information about the microscopic behavior that can be potentially used to tailor the response of lead-free relaxor ferroelectrics and bring them closer to the highly performant lead-based perovskites
Objavljeno v DiRROS: 13.06.2025; Ogledov: 78; Prenosov: 21
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2. Uncertainty and sensitivity analysis for hot-leg LOCA in two-loop PWRAndrej Prošek, 2025, izvirni znanstveni članek Povzetek: Overcooling and/or pressurization events have the potential to result in pressurized thermal shock (PTS) in reactor pressure vessels of pressurized water reactors (PWRs). PTS can occur during various overcooling scenarios, including loss-of-coolant accidents (LOCAs). Thermal-hydraulic calculations of overcooling scenarios provide an input to structural analysis. The purpose of this study is to perform advanced thermal-hydraulic calculations of a hot-leg LOCA with uncertainty and sensitivity analyses. A novel approach, utilizing a fast Fourier transform–based method (FFTBM) with signal mirroring (SM), is proposed for a sensitivity study to evaluate the influence of input uncertain parameters with low computational cost before performing an uncertainty analysis. For the analysis, a break size of 45.6 cm2 (equivalent to a 76.2-mm- or 3-in.-equivalent diameter) was selected in a two-loop PWR. A verified and validated RELAP5 input deck was used. In sensitivity study 30, one-at-a-time sensitivity calculations plus reference calculation were performed. These were followed by uncertainty and sensitivity analyses using the GRS (Gesellschaft für Anlagen- und Reaktorsicherheit) Software for Uncertainty and Sensitivity Analyses (SUSA) version 4.2.6 tool, varying 15 uncertain input parameters across 208 samples. The input uncertain parameters were derived from the European Union–funded Advanced PTS Analysis for LTO (APAL) project. Three figures of merit (FOMs), reactor pressure, liquid temperature, and reactor vessel wall temperature below the cold leg connection, were analyzed. The results demonstrated that FFTBM-SM effectively identified the four most influential parameters, aligning closely with the results from the global sensitivity analysis from SUSA, which utilized 208 samples from the uncertainty analysis. Although slight differences in parameter ranking were observed, the findings validate FFTBM-SM as a valuable prescreening tool for sensitivity studies. The limitation of the sensitivity study is that it adopts a local approach. Finally, the results of the uncertainty analysis provide tolerance regions for the selected FOMs that are comparable to those obtained in the original APAL study for a four-loop PWR.
Ključne besede: uncertainty analysis, sensitivity analysis, FFTBM-SM, advancedthermal-hydraulic calculations of a hot-leg LOCA
Objavljeno v DiRROS: 11.06.2025; Ogledov: 117; Prenosov: 42
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3. Zr and Zr-Cr commercial conversion coatings deposited on 3003 aluminium alloy foilMaja Mujdrica Kim, Barbara Kapun, Ingrid Milošev, 2025, izvirni znanstveni članek Povzetek: MAVOMcoat MC1300 (Zr-Cr-based coating) and MC1700 (Zr-based coating) on chemically pre-treated aluminium alloy 3003. Conversion times varied from 80 s to 45 min. After deposition, the samples were subjected to three post-treatments: air drying for 15 min, air drying for 24 h, and immersion in 3.5 wt% NaCl solution for 24 h. Corrosion resistance was evaluated using electrochemical measurements, whereas scanning electron microscopy with energy dispersive spectroscopy and X-ray photoelec tron spectroscopy were employed for surface analysis. Based on the evaluation of corrosion parameters, the optimal conversion times for MC1700 and MC1300 were determined to be 10 min and 7 min, respectively. The conversion coatings MC1700 and MC1300 were characterised by distinct elemental compositions, with the former predominantly comprising Zr, O, Al and F, and the latter Zr, O, Al, Cr and F. Notably, the thickness of coatings was between 10 and 170 nm, depending on the type of coating and location (matrix or intermetallic particles). The 24-hour immersion of MC1700 ZrCC in 3.5 wt% NaCl led to progressive build-up of Zr oxide and release of fluoride from the coating.
Objavljeno v DiRROS: 10.06.2025; Ogledov: 123; Prenosov: 35
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5. Elastic properties of domains and domain walls in ▫$(K_{0.5}Na_{0.5})NbO_3$▫ single crystalKatarina Žiberna, Maja Koblar, Andraž Bradeško, Micka Bah, Franck Levassort, Goran Dražić, Hana Uršič Nemevšek, Andreja Benčan, 2025, izvirni znanstveni članek Ključne besede: domains, potassium sodium niobite
Objavljeno v DiRROS: 09.06.2025; Ogledov: 82; Prenosov: 36
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6. Applicability assessment of technologies for predictive and prescriptive analytics of nephrology big dataRiste Stojanov, Milos Jovanovik, Sasho Gramatikov, Ivona Vasileska, Tome Eftimov, Dimitar Trajanov, 2025, pregledni znanstveni članek Povzetek: The integration of big data into nephrology research will open new avenues for analyzing and understanding complex biological datasets, driving advances in personalized management of kidney diseases. This paper describes the multifaceted challenges and opportunities by incorporating big data in nephrology, emphasizing the importance of data standardization, advanced storage solutions, and advanced analytical methods. We discuss the role of data science workflows, including data collection, preprocessing, integration, and analysis, in facilitating comprehensive insights into disease mechanisms and patient outcomes. Furthermore, we highlight predictive and prescriptive analytics, as well as the application of large language models (LLMs) in improving clinical decision-making and enhancing the accuracy of disease predictions. The use of high-performance computing (HPC) is also examined, showcasing its role in processing large-scale datasets and accelerating machine learning algorithms. Through this exploration, we aim to provide a comprehensive overview of the current state and future directions of big data analytics in nephrology, with a focus on enhancing patient care and advancing medical research.
Ključne besede: large language models, data standardization
Objavljeno v DiRROS: 04.06.2025; Ogledov: 119; Prenosov: 46
Celotno besedilo (1,06 MB)
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7. Efficient decoration of graphene oxide with a narrow size distribution of noble metal nanoparticles : green reduction and integration into a thermoelastic compositeDaniele Vella, Damjan Vengust, Polona Umek, Ali Rezaei, Matija Jezeršek, Aleš Mrzel, 2025, izvirni znanstveni članek Povzetek: We have developed a significantly enhanced method for the effective and homogeneous decoration of graphene oxide (GO) and reduced graphene oxide (r-GO) flakes with gold (Au) and platinum (Pt) nanoparticles. This method involves the direct nucleation of nanoparticles on the surface of dispersed GO through a single-step reaction. By carefully controlling the stepwise introduction of gold and platinum complexes at elevated temperatures, without additional reducing agents, we successfully achieved a homogeneous distribution of Au and Pt nanoparticles, ∼ 20 nm and ∼ 3 nm in size, densely covering the GO sheets. The decoration yield in a mass ratio between Au and GO was up to 20 %. Reduced GO with attached gold and platinum nanoparticles was obtained using ascorbic acid as a reducing agent. Finally, we embedded Au-decorated r-GO in polydimethylsiloxane (PDMS) to form a composite. We show how this stable hybrid material composite can be spin-coated to form a thin thermoelastic film on a flexible substrate, enabling promising photoacoustic properties that could be exploited further in biomedical applications.
Ključne besede: graphene oxide, decoration, nanoparticles, nanocomposites
Objavljeno v DiRROS: 04.06.2025; Ogledov: 118; Prenosov: 57
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8. Curvature-dependent adsorption of surfactants in water nanodroplets and nanobubblesFabio Staniscia, Matej Kanduč, 2025, izvirni znanstveni članek Povzetek: Hypothesis. Surfactants, molecules that readily adsorb to liquid interfaces and reduce surface tension, are paramount to numerous natural and technological processes: from cloud formation and climate modeling to the stability and reactivity of nanodroplets and nanobubbles. While surfactant adsorption at planar interfaces has been well-studied, their behavior at curved interfaces remains much less understood. Since curvature modifies interfacial thermodynamic properties, we hypothesize that it will also affect surfactant adsorption. Simulations. To test this hypothesis, we perform molecular dynamics simulations of short-chain surfactants at water–vapor interfaces with varying curvature, examining droplets, bubbles, and planar interfaces. Findings. The outcomes reveal a systematic dependence of adsorption on curvature, which is enhanced at droplet interfaces and reduced at bubble interfaces, with the effect becoming more pronounced for surfactants with longer alkyl tails. We attribute this curvature-dependent behavior to two key mechanisms: Laplace pressure and curvature-dependent surface tension. The breakdown of these contributions allows us to obtain a quantitative understanding and to predict the influence of curvature on adsorption.
Ključne besede: droplets, bubbles, molecular dynamics simulation
Objavljeno v DiRROS: 04.06.2025; Ogledov: 145; Prenosov: 51
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9. Composition, microstructure and corrosion resistance of DED-LB additively manufactured Ti–6Al–4V alloy : comparison with wrought alloyIngrid Milošev, Peter Rodič, Barbara Kapun, Denis Sačer, Anish Nair, Davorin Kramar, Andrej Jeromen, Edvard Govekar, 2025, izvirni znanstveni članek Ključne besede: titanium alloys, directed-energy deposition by laser beam, simulated physiological solution
Objavljeno v DiRROS: 03.06.2025; Ogledov: 148; Prenosov: 64
Celotno besedilo (30,07 MB)
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