1. Surface phase diagrams of pristine and hydroxylated barium hexaferrite surfaces from first-principles atomistic thermodynamicsMatic Poberžnik, Gabriela Herrero-Saboya, Darko Makovec, Darja Lisjak, Layla Martin-Samos, 2023, izvirni znanstveni članek Povzetek: Barium hexaferrite (BHF) is a ferrimagnet, whose hexagonal unit cell presents five iron crystallographic sites along the -axis. At the nanoscale, BHF nanoparticles grow in the form of platelets, characterized by a low thickness along its principal magnetization axis ( -axis), displaying uniaxial magnetic anisotropy with the easy axis pointing perpendicular to the platelet. This unique property of BHF nanoplatelets has lead to a variety of novel applications, which often require surface functionalization. However, it has been observed that the nanoplatelets display two different surface morphologies depending on the stage/conditions of preparation. To ground these experimental observations, we employ the ab initio thermodynamics framework to perform a systematic investigation of the thermodynamic stability of BHF bulk terminations under a wide range of chemical conditions. We calculate the surface phase diagrams of pristine and hydroxylated bulk terminations along the -axis. For pristine terminations, two different iron terminated surfaces are preferred: the barium containing 2b termination (Ba-rich conditions) and the 4f iron terminated surface (Ba-poor conditions). In the presence of water, the hydroxylated oxygen-terminated surfaces (12k-O) are identified as the most stable ones at Ba-poor conditions and low pH values, whereas the hydroxylated 2b surface is preferred at high pH and Ba-rich conditions.
Objavljeno v DiRROS: 15.04.2025; Ogledov: 241; Prenosov: 101
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2. Electrified dynamically responsive ammonia decomposition to hydrogen based on magnetic heating of a Ru nanocatalystŽiga Ponikvar, Anja Sedminek, Janvit Teržan, Luka Skubic, Žan Lavrič, Matej Huš, Miha Grilc, Blaž Likozar, Darko Makovec, Sašo Gyergyek, 2024, izvirni znanstveni članek Povzetek: Storing and transporting pressurized or liquid hydrogen is expensive and hazardous. As a result, safer methods, such as chemical storage in ammonia, are becoming increasingly important. However, the instantaneous start of a conventionally heated decomposition reactor is challenging. Here we report on the electrified and dynamically responsive decomposition of ammonia as a means of releasing on-demand chemically bonded hydrogen based on the rapid magnetic heating of a well-designed Ru-based nanocomposite catalyst. Under relatively mild conditions (400 °C, 1 bar) a rapid decomposition rate of 5.33 molNH3 gRu-1 h-1 was achieved. Experimental observations under non-isothermal, dynamic conditions coupled with modelling at the level of density functional theory and micro-kinetic modeling confirmed the minute-scale response of the H2 release. The rapid response of our catalytic system would, at least in principle, enable the utilization of intermittent, renewable electricity and a tunable H2/NH3 ratio in the reactor’s effluent.
Objavljeno v DiRROS: 25.03.2025; Ogledov: 239; Prenosov: 65
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3. Cytotoxicity assessment of HDPE microplastic on Tetrahymena thermophila (Protozoa, Ciliate) : assuring quality and FAIR dataValentina Perc, Veno Kononenko, Nina Jeliaskova, Matej Hočevar, Slavko Kralj, Darko Makovec, Maja Caf, Damjana Drobne, Sara Novak, 2024, izvirni znanstveni članek Ključne besede: cytotoxicity, microplastic, HDPE, FAIR data, tetrahymena thermophila
Objavljeno v DiRROS: 16.12.2024; Ogledov: 421; Prenosov: 191
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4. Inflammatory, oxidative stress and small cellular particle response in HUVEC induced by debris from endoprosthesis processingZala Jan, Matej Hočevar, Veno Kononenko, Sara Michelini, Neža Repar, Maja Caf, Boštjan Kocjančič, Drago Dolinar, Slavko Kralj, Darko Makovec, Aleš Iglič, Damjana Drobne, Monika Jenko, Veronika Kralj-Iglič, 2023, izvirni znanstveni članek Ključne besede: endoprosthesis failure, corundum, cytokines, reactive oxygen species, lipid droplets
Objavljeno v DiRROS: 02.02.2024; Ogledov: 1121; Prenosov: 434
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5. Saturation magnetisation as an indicator of the disintegration of barium hexaferrite nanoplatelets during the surface functionalisationDarja Lisjak, Iztok Arčon, Matic Poberžnik, Gabriela Herrero‑Saboya, Ali Tufani, Andraž Mavrič, Matjaž Valant, Patricija Hribar, Alenka Mertelj, Darko Makovec, Layla Martin‑Samos, 2023, izvirni znanstveni članek Objavljeno v DiRROS: 02.02.2023; Ogledov: 1585; Prenosov: 955
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