1021. Design and implementation of the SRT control at the Ljubljana WWTPDarko Vrečko, Nadja Hvala, Rok Babič, 2025, original scientific article Abstract: he solid retention time (SRT) is one of the most important parameters for the operation of a wastewater treatment plant (WWTP). Maintaining the SRT at the prescribed set-point is necessary to achieve an appropriate food-to-microorganism (F/M) ratio. This article describes the design and implementation of SRT control at the Ljubljana WWTP. The designed SRT control wastes a defined proportion of the mixed liquor suspended solid (MLSS) mass in the aerobic reactors. The sludge wasted from the secondary settlers is determined based on measurements of the MLSS concentration, waste sludge concentration, and waste sludge flow rate. The SRT control is simple and does not require an SRT estimation or an SRT feedback controller. It includes a constraining controller that keeps the MLSS in the aerobic reactors within the prescribed minimum and maximum values. Validation of the designed SRT control on a mathematical model of the Ljubljana WWTP shows better set-point tracking than the proportional integral (PI) SRT control, as well as reduced SRT variations and lower ammonia nitrogen concentrations compared to the initial MLSS control. The testing of the designed SRT control at the Ljubljana WWTP confirmed the set-point tracking and reduced SRT variations despite large influent variations and operational disturbances.
Keywords: waste sludge control, solid retention time
Published in DiRROS: 23.09.2025; Views: 268; Downloads: 118
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1022. Water-based pharmacophore modeling in kinase inhibitor design : a case study on fyn and lyn protein kinasesMartin Ljubič, Marija Sollner Dolenc, Jure Borišek, Andrej Perdih, 2025, original scientific article Abstract: Water-based pharmacophore modeling is an emerging approach in inhibitor design that leverages the dynamics of explicit water molecules within ligand-free, water-filled binding sites to derive 3D pharmacophores for virtual screening. In this study, we assess the potential of this strategy through a case study targeting the ATP binding sites of Fyn and Lyn protein kinases─members of the Src family that have been less explored in anticancer drug discovery compared to other family members. Molecular dynamics simulations of multiple kinase structures were used to generate and validate several water-derived pharmacophores, which were subsequently employed to screen chemically diverse libraries of compounds. Two active compounds were identified in biochemical assays: a flavonoid-like molecule with low-micromolar inhibitory activity and a weaker inhibitor from the library of nature-inspired synthetic compounds. Structural analysis via molecular docking and simulations revealed that key predicted interactions, particularly with the hinge region and the ATP binding pocket, were retained in the bound states of these hits. However, interactions with more flexible regions, such as the N-terminal lobe and activation loop, were less consistently captured. These findings outline both the strengths and challenges of using water-based pharmacophores: while effective at modeling conserved core interactions, they may miss peripheral contacts governed by protein flexibility. Incorporating ligand information where available may help address this challenge. Overall, water-based pharmacophore modeling presents a promising ligand-independent strategy for identifying novel chemotypes and exploring undercharged chemical and conformational space in kinases as well as other therapeutically relevant targets.
Keywords: drug discovery, inhibitors, ligands, peptides, proteins, pharmacophores
Published in DiRROS: 23.09.2025; Views: 278; Downloads: 144
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1023. Spreading in claw-free cubic graphsBoštjan Brešar, Jaka Hedžet, Michael A. Henning, 2025, original scientific article Abstract: Let $p\in\mathbb{N}$ and $q\in\mathbb{N}\cup\{\infty\}$. We study a dynamic coloring of the vertices of a graph $G$ that starts with an initial subset $S$ of blue vertices, with all remaining vertices colored white. If a white vertex $v$ has at least $p$ blue neighbors and at least one of these blue neighbors of $v$ has at most $q$ white neighbors, then by the spreading color change rule the vertex $v$ is recolored blue. The initial set $S$ of blue vertices is a $(p,q)$-spreading set for $G$ if by repeatedly applying the spreading color change rule all the vertices of $G$ are eventually colored blue. The $(p,q)$-spreading set is a generalization of the well-studied concepts of $k$-forcing and $r$-percolating sets in graphs. For $q\ge2$, a $(1,q)$-spreading set is exactly a $q$-forcing set, and the $(1,1)$-spreading set is a $1$-forcing set (also called a zero forcing set), while for $q=\infty$, a $(p,\infty)$-spreading set is exactly a $p$-percolating set. The $(p,q)$-spreading number, $\sigma_{(p,q)}(G)$, of $G$ is the minimum cardinality of a $(p,q)$-spreading set. In this paper, we study $(p,q)$-spreading in claw-free cubic graphs. While the zero-forcing number of claw-free cubic graphs was studied earlier, for each pair of values $p$ and $q$ that are not both $1$ we either determine the $(p,q)$-spreading number of a claw-free cubic graph $G$ or show that $\sigma_{(p,q)}(G)$ attains one of two possible values.
Keywords: bootstrap percolation, zero forcing set, k-forcing set, spreading
Published in DiRROS: 23.09.2025; Views: 226; Downloads: 110
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1024. Luminescent sensing of Hg²⁺ ions using MOF-808 combined with ▫$Au_ {25}$▫@BSA nanoclustersLudovico Giuseppe Barbata, Matjaž Mazaj, Romy Ettlinger, Giuseppe Ficarra, Pietro Castronovo, Alice Sciortino, Fabrizio Messina, Russell E. Morris, Gianpiero Buscarino, 2025, original scientific article Published in DiRROS: 23.09.2025; Views: 315; Downloads: 130
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1026. Enhancing ex situ cultivation of Mediterranean Fucales: species-specific responses of Gongolaria barbata and Ericaria crinita seedlings to algal extractsAna Lokovšek, Martina Orlando-Bonaca, Edi Gljušćić, Andrea Bilajac, Ljiljana Iveša, Alberta Di Cave, Saverio Savio, Federico Ortenzi, Domen Trkov, Roberta Congestri, Annalisa Falace, 2025, original scientific article Abstract: Mediterranean brown algal forests, dominated by Cystoseira sensu lato species, are undergoing widespread decline due to the cumulative effects of anthropogenic pressure and climate-related stressors. Restoration efforts increasingly rely on ex situ cultivation and outplanting of seedlings, yet early developmental stages often suffer from low survival and growth rates. This study investigated the potential of algal extracts to enhance the seedling development and survival in two canopy-forming species, Gongolaria barbata and Ericaria crinita. We tested extracts from a cyanobacterium (Trichormus variabilis), two microalgae (Desmodesmus sp. and Cylindrotheca closterium), and a commercial macroalgal formulation (AlgatronCifo®) at varying concentrations under controlled mesocosm conditions. Seedling performance was significantly influenced by extract type, and target species identity. Notably, a low-concentration Desmodesmus sp. extract (0.07 mg mL− 1 ) improved survival and growth, whereas T. variabilis exerted an inhibitory effect on G. barbata. AlgatronCifo® did not outperform Desmodesmus sp. extract in promoting seedling development. These findings suggest that specific extracts from green microalgae could improve protocols for the early stages of restoration, offering a scalable tool for rehabilitating degraded marine forests. However, the results underscore the importance of species-specific optimization and the need for in situ validation of biostimulant-based restoration approaches.
Keywords: Cystoseira s.l., seaweed biostimulants, microalgal extracts, seedling development, restoration, Mediterranean sea
Published in DiRROS: 22.09.2025; Views: 322; Downloads: 136
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1027. Paleoenvironmental and neotectonic insights from the pliocene fossil record of Velika Pasica Cave, Slovenia: implications for karst system evolutionAndrej Mihevc, Ivan Horáček, Nadja Zupan Hajna, Jon Woodhead, Anton Brancelj, 2025, original scientific article Abstract: Velika Pasica Cave, situated on a karst plateau at an altitude of 665 meters above sea level, offers a unique record of paleontological, speleological, and tectonic processes. The cave, predominantly filled with allogenic sediments and speleothems, contains fossilized remains of the aquatic cave invertebrate Marifugia cavatica and terrestrial small mammals, characteristic of the early Pliocene (MN15–16). Paleontological dating estimates the cave sediments to be approximately 4 Ma old, while U/Th dating of the overlying flowstone indicates deposition at 410 ± 21 ka. These findings suggest that stagnant phreatic conditions prevailed prior to tectonic uplift and basin subsidence, which reshaped the karst landscape. This study highlights the dynamic interplay between neotectonics, karst system evolution, and biodiversity changes. By integrating speleobiology, geomorphology, and biostratigraphy, it provides valuable in-sights into the environmental history of the northern Dinarides and the impact of geological processes on karst ecosystems.
Keywords: paleontology, Marifugia cavatica, small mammals, karst geomorphology, cave sediments dating, tectonic
Published in DiRROS: 22.09.2025; Views: 246; Downloads: 141
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1029. Progress achieved in EURAMET project 21GRD09 MetroPOEM : Metrology for the harmonisation of measurements of environmental pollutants in EuropeDirk Arnold, Rasmus Andreasen, Oktay Cankur, Karin Hain, Razvan-Ioan Costa, Johanna Irrgeher, Steffen Happel, Johanna Noireaux, Tea Zuliani, 2025, published scientific conference contribution Published in DiRROS: 22.09.2025; Views: 282; Downloads: 125
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1030. Cathodic arc-deposited AlTiN hard coating tribology at elevated temperaturesAljaž Drnovšek, Patrik Šumandl, Žan Gostenčnik, Janez Kovač, Miha Čekada, 2025, original scientific article Abstract: Cathodic arc evaporation (CAE) is the most commonly used physical vapor deposition (PVD) method to deposit protective coatings on cutting and forming tools. However, this deposition method results in a relatively rough surface due to micro-droplet emission. The first contact between the coating and the workpiece surface is at the sites of these growth defects, influencing the state of the contact, such as particle formation and oxidation spots. Growth defects significantly impact the coating's wear and friction properties. Their impact is not limited to the beginning of the contact formation but also expands in the long run, and they can deteriorate the coatings much sooner than expected. This research aims to monitor the wear and friction properties of the cathodic arc deposited AlTiN hard coating during the running-in and steady-state periods under different temperature conditions. Tribological tests against the Al2O3 counterbody were carried out at different temperatures, from room temperature up to 700 °C. The sliding distance at specific temperatures, ranging from 50 to 140,000 cycles, enabled us to monitor the wear progression from first contact formation at the growth defects to the complete coating wear from the WC-Co substrate. After tribological tests, the samples were analyzed using detailed 3D profilometry, SEM, and FIB analysis to determine the wear mechanisms in different stages of high-temperature wear. Attention was focused on the growth defects, their impact on the running-in behavior, and the oxygen diffusion pathways along growth defects that ultimately lead to the delamination of the coating from the substrate.
Keywords: cathodic arc evaporation, physical vapor deposition, growth defects
Published in DiRROS: 19.09.2025; Views: 367; Downloads: 157
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