31. Spectroscopic characterization using 1H and 13C nuclear magnetic resonance and computational analysis of the complex of donepezil with 2,6-methyl-β-cyclodextrin and hydroxy propyl methyl celluloseNikoletta Zoupanou, Paraskevi Papakyriakopoulou, Nikitas Georgiou, Antigoni Cheilari, Uroš Javornik, Peter Podbevšek, Demeter Tzeli, Georgia Valsami, Thomas Michael Mavromoustakos, 2025, original scientific article Published in DiRROS: 15.04.2025; Views: 40; Downloads: 15
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34. Efficient and selective biosynthesis of a precursor-directed FK506 analogue : paving the way for click chemistryDušan Goranovič, Branko Jenko, Barbara Ramšak, Ajda Podgoršek Berke, Leon Bedrač, Jaka Horvat, Martin Šala, Damjan Makuc, Guilhermina M. Carriche, Luana Silva, Aleksandra Lopez Krol, Alen Pšeničnik, Maria Beatriz Duran Alonso, Martina Avbelj, Stojan Stavber, Janez Plavec, Tim Sparwasser, Rolf Müller, Gregor Kosec, Štefan Fujs, Hrvoje Petković, 2025, original scientific article Abstract: The medically important immunosuppressant FK506 is a structurally complex macrolactone biosynthesized by a combined polyketide synthase and a nonribosomal peptide synthetase enzyme complex. Its acyltransferase domain 4 (AT4) selects an unusual extender unit, resulting in an allyl moiety on carbon 21 of the macrolactone backbone. Based on the AT4 domain, chemobiosynthetic processes have been developed that enable the introduction of diverse moieties at the carbon 21 position. However, the novel moieties that were introduced into the polyketide backbone are chemically inert. Reported here is a novel and efficient chemobiosynthetic approach that ensures high titer of an FK506 analogue containing a propargyl moiety. The novel FK506 analogue displays lower immunosuppression activity than FK506 with significantly reduced cytotoxicity. More importantly, the propargyl moiety contains a terminal alkyl group, which makes click chemistry reactions possible; this approach may potentially be translated to other medically important drugs of polyketide origin.
Published in DiRROS: 15.04.2025; Views: 49; Downloads: 6
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35. Experimental approach and assessment of Zr conversion coatings on Al alloy using response surface methodologyAna Kraš, Davorin Kramar, Ingrid Milošev, 2025, original scientific article Abstract: This study extended the use of response surface methodology (RSM) to explore the experimental space, identify optimal conditions for deposition and drying, and assess factor interactions for zirconium conversion coatings on aluminium alloy 5754. Corrosion resistance in a dilute Harrison's solution was evaluated using a non-electrochemical drop test and electrochemical techniques. Surface analysis supported the electrochemical findings obtained with the chosen RSM conditions. Unlike zinc and cold-rolled steel, AA5754 exhibits heightened sensitivity to the interplay of pH, conversion time, and H2ZrF6 concentration, which is attributed to the presence of intermetallic particles governing cathodic reactions and the subsequent conversion processes.
Keywords: aluminium, EIS (Electrochemical Impedance Spectroscopy), response surface methodology, conversion coatings
Published in DiRROS: 15.04.2025; Views: 41; Downloads: 9
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36. Atypical adsorption of hydrogen on native ultrathin aluminum oxide filmsMatic Poberžnik, Anton Kokalj, 2025, original scientific article Abstract: We report on an unusual hydrogen adsorption mode on native ultrathin aluminum-oxide films. Based on systematic density-functional theory (DFT) calculations on a model oxide film of varying thickness—i.e., α–Al2O3(001) supported on Al(111)—we show that on ultrathin films, H preferentially adsorbs on surface Al ions instead of O ions, as one would expect from chemical intuition. The so-adsorbed H is in hydride form, and for ultrathin films, it gets the electron charge from Al atoms at the oxide/metal interface. In contrast, for thicker films, this electron transfer ceases, and the charge instead predominantly comes from the surface O ions, making H adsorbed at Al sites inferior to H adsorbed at O sites. We further show that H adsorbed at Al sites can lead to H2 formation, which we propose to be connected to the experimentally observed hydrogen evolution in pits formed during the pitting corrosion of aluminum, where the protective oxide film has considerably degraded and is very thin
Published in DiRROS: 15.04.2025; Views: 39; Downloads: 5
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37. Superhydrophobic coatings based on PMMA-siloxane-silica and modified silica nanoparticles deposited on AA2024-T3Nina Kovač, Barbara Kapun, Matic Može, Iztok Golobič, Slavko Kralj, Ingrid Milošev, Peter Rodič, 2025, original scientific article Abstract: The study aimed to develop a superhydrophobic coating on the aluminium alloy 2024-T3 surface. The desired surface roughness and low surface energy were achieved with SiO2 nanoparticles, synthesised via the Stöber method and modified with alkyl silane (AS) or perfluoroalkyl silane (FAS). To enhance particle adhesion to the alloy substrate, nanoparticles were incorporated into a hybrid sol–gel coating composed of tetraethyl orthosilicate, methyl methacrylate, and 3-methacryloxypropyl trimethoxysilane. The coated substrates were characterised using field emission scanning and transmission electron microscopy with energy-dispersive spectroscopy for surface topography, nanoparticle size distribution, composition, and coating thickness. The corrosion resistance of the coatings on AA2024-T3 was evaluated in a 0.1 M NaCl solution using electrochemical impedance spectroscopy. The synthesised SiO2 nanoparticles had an average size between 25 and 35 nm. The water contact angles on coated aluminium surfaces reached 135° for SiO2 + AS and 151° for SiO2 + FAS. SiO2 + FAS, indicating superhydrophobic properties, showed the most uniform surface with the most consistent size distribution of the SiO2 nanoparticles. Incorporation of nanoparticles into the hybrid sol–gel coating further improved particle adhesion. The ~2 µm-thick coating also demonstrated efficient barrier properties, significantly enhancing corrosion resistance for over two months under the test conditions.
Keywords: nanoparticles, hybrid sol–gel, adhesion
Published in DiRROS: 15.04.2025; Views: 40; Downloads: 9
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38. Characterisation of the deposition and protection performance of Zr conversion coatings on steel and zinc substrates using the response surface methodologyAna Kraš, Davorin Kramar, Ingrid Milošev, 2025, original scientific article Abstract: The response surface methodology (RSM) was used to explore the experimental space, characterise the influence of deposition and drying conditions on corrosion resistance, and evaluate the interactions between these factors for zirconium conversion coatings on cold-rolled steel and zinc. A combination of non-electrochemical drop tests and electrochemical methods were utilised to evaluate corrosion resistance in a dilute Harrison's solution. The surface analysis confirmed the electrochemical results obtained under the conditions chosen by RSM. The uniform corrosion of both substrates guides the subsequent conversion process, while the best coating performance results from the interaction of pH, conversion time and bath concentration.
Keywords: response surface methodology, conversion coatings, thermodynamic data
Published in DiRROS: 15.04.2025; Views: 44; Downloads: 13
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39. 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, original scientific article Abstract: 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.
Published in DiRROS: 15.04.2025; Views: 60; Downloads: 23
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40. Integration of multi-omics data and deep phenotyping provides insights into responses to single and combined abiotic stress in potatoMaja Zagorščak, Lamis Abdelhakim, Natalia Yaneth Rodriguez-Granados, Carissa Bleker, Andrej Blejec, Jan Zrimec, Špela Baebler, Anže Županič, Maruša Pompe Novak, Kristina Gruden, 2025, original scientific article Abstract: Potato (Solanum tuberosum) is highly water and space efficient but susceptible to abiotic stresses such as heat, drought, and flooding, which are severely exacerbated by climate change. Our understanding of crop acclimation to abiotic stress, however, remains limited. Here, we present a comprehensive molecular and physiological high-throughput profiling of potato (Solanum tuberosum, cv. Désirée) under heat, drought, and waterlogging applied as single stresses or in combinations designed to mimic realistic future scenarios. Stress responses were monitored via daily phenotyping and multi-omics analyses of leaf samples comprising proteomics, targeted transcriptomics, metabolomics, and hormonomics at several timepoints during and after stress treatments. Additionally, critical metabolites of tuber samples were analyzed at the end of the stress period. We performed integrative multi-omics data analysis using a bioinformatic pipeline that we established based on machine learning and knowledge networks. Waterlogging produced the most immediate and dramatic effects on potato plants, interestingly activating ABA responses similar to drought stress. In addition, we observed distinct stress signatures at multiple molecular levels in response to heat or drought and to a combination of both. In response to all treatments, we found a downregulation of photosynthesis at different molecular levels, an accumulation of minor amino acids, and diverse stress-induced hormones. Our integrative multi-omics analysis provides global insights into plant stress responses, facilitating improved breeding strategies toward climate-adapted potato varieties.
Keywords: potato, Solanum tuberosum, abiotic stress responses, heat, drought, waterlogging, multi-omics, integrative omics, adaptomics, panomics
Published in DiRROS: 14.04.2025; Views: 63; Downloads: 32
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