1. Advancing energy recovery: evaluating torrefaction temperature effects on food waste properties from fruit and vegetable processingAndreja Škorjanc, Sven Gruber, Klemen Rola, Darko Goričanec, Danijela Urbancl, 2025, izvirni znanstveni članek Opis: Most organic waste from food production is still not used for energy production. From the perspective of energy production, one option is to valorise the properties of organic waste. The fruit juice industry is growing rapidly and generates large amounts of waste. One of the main wastes in food and fruit juice processing is peach pits and apple peels. The aim of this study was to analyse the influence of torrefaction temperature on the properties of food waste, namely apple peels, peach pits and pea shells, in order to improve their energy value and determine their potential for further use and valorisation as a renewable energy source. The aim was to analyse the influence of different torrefaction temperatures on the heating value (HHV), mass yield (MY) and energy yield (EY) in order to better understand the behavior of the thermal properties of individual selected samples. The torrefaction process was carried out at temperatures of 250 ◦C, 350 ◦C and 450 ◦C. The obtained biomass was compared with dried biomass. For apple peels, HHV after torrefaction was (28 kJ/kg), MY decreased by (66–34%), while EY fell by (97–83%). Peach pits, despite a higher HHV after torrefaction (18 kJ/kg), achieved low MY (38–89%) and EY (59–99%), which reduces their efficiency in biochar production. Pea peels had EY (82–97%) and a lower HHV after torrefaction (11 kJ/kg), but their high ash content limits their wider use. The results confirm that, with increasing temperature, MY and EY for all selected biomasses decrease, which is a consequence of the degradation of hemicellulose and cellulose and the loss of volatile compounds. In most cases, increasing the torrefaction temperature improved the resistance to moisture adsorption, as this is related to the thermal process that causes structural changes. The results showed that the torrefaction process improved the hydrophobic properties of the biomass samples. Temperature was seen to have a great impact on mass energy efficiency. Apple peels generally had the highest mass and energy yield. Ključne besede: torrefaction, food waste, energy from waste, higher heating value, energy potential Objavljeno v DKUM: 07.02.2025; Ogledov: 0; Prenosov: 5
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2. Novel GPU-accelerated high-resolution solar potential estimation in urban areas by using a modified diffuse irradiance modelNiko Lukač, Domen Mongus, Borut Žalik, Gorazd Štumberger, Marko Bizjak, 2024, izvirni znanstveni članek Opis: In the past years various methods have been developed to estimate high-resolution solar potential in urban areas, by simulating solar irradiance over surface models that originate from remote sensing data. In general, this requires discretisation of solar irradiance models that estimate direct, reflective, and diffuse irradiances. The latter is most accurately estimated by an anisotropic model, where the hemispherical sky dome from arbitrary surface’s viewpoint consists of the horizon, the circumsolar and sky regions. Such model can be modified to incorporate the effects of shadowing from obstruction with a view factor for each sky region. However, state-of-the-art using such models for estimating solar potential in urban areas, only considers the sky view factor, and not circumsolar view factor, due to high computational load. In this paper, a novel parallelisation of solar potential estimation is proposed by using General Purpose computing on Graphics Processing Units (GPGPU). Modified anisotropic Perez model is used by considering diffuse shadowing with all three sky view factors. Moreover, we provide validation based on sensitivity analysis of the method’s accuracy with independent meteorological measurements, by changing circumsolar sky region’s half-angle and resolution of the hemispherical sky dome. Finally, the presented method using GPPGU was compared to multithreaded Central Processing Unit (CPU) approach, where on average a 70x computational speedup was achieved. Finally, the proposed method was applied over a urban area, obtained from Light Detection And Ranging (LiDAR) data, where the computation of solar potential was performed in a reasonable time. Ključne besede: solar energy, solar potential, anisotropic diffuse irradiance, LiDAR, GPGPU Objavljeno v DKUM: 17.12.2024; Ogledov: 0; Prenosov: 3
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3. Mesenchymal stem cells isolated from paediatric paravertebral adipose tissue show strong osteogenic potentialJan Rožanc, Lidija Gradišnik, Tomaž Velnar, Minja Gregorič, Marko Milojević, Boštjan Vihar, Boris Gole, Uroš Maver, 2022, izvirni znanstveni članek Opis: Mesenchymal stem cells (MSCs) represent the basis of novel clinical concepts in cellular therapy and tissue regeneration. Therefore, the isolation of MSCs from various tissues has become an important endeavour for stem cell biobanking and the development of regenerative therapies. Paravertebral adipose tissue is readily exposed during spinal procedures in children and could be a viable source of stem cells for therapeutic applications. Here, we describe the first case of MSCs isolated from paravertebral adipose tissue (PV-ADMSCs), obtained during a routine spinal surgery on a child. Using quantitative real-time PCR and flow cytometry, we show that PV-ADMSCs have different levels of stem marker expression compared to the MSCs from other sources while having the highest proliferation rate. Furthermore, we evaluate the multipotency of PV-ADMSCs by the three-lineage (adipogenic, osteogenic and chondrogenic) differentiation and compare it to the multipotency of MSCs from other sources. It was found that the PV-ADMSCs have a strong osteogenic potential in particular. Taken together, our data indicate that PV-ADMSCs meet the criteria for successful cell therapy, defined by the International Society for Cellular Therapy (ISCT), and thus, could provide a source of MSCs that is relatively easy to isolate and expand in culture. Due to their strong osteogenic potential, these cells provide a promising basis, especially for orthopaedic applications. Ključne besede: mesenchymal stem cells, paediatric surgery, paravertebral adipose tissue, regenerative medicine, stem marker expression, osteogenic potential, differentiation Objavljeno v DKUM: 16.12.2024; Ogledov: 0; Prenosov: 5
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4. Antimicrobial activity of amino-modified cellulose nanofibrils decorated with silver nanoparticlesVesna Lazić, Jovan Nedeljković, Vanja Kokol, 2024, izvirni znanstveni članek Opis: Silver nanoparticles (Ag NPs) conjugated with amino-functionalized cellulose nanofibrils (NH2−CNFs) were in situ-prepared by reducing silver ions with free amino groups from NH2−CNFs. The spectroscopy and transmission electron microscopy measurements confirmed the presence of non-agglomerated nanometer-in-size Ag NPs within micrometer-large NH2−CNFs of high (20 wt.-%) content. Although the consumption of amino groups during the formation of Ag NPs lowers the ζ-potential and surface charge of prepared inorganic–organic hybrids (from +31.3 to +19.9 mV and from 2.4 to 1.0 mmol/g at pH 7, respectively), their values are sufficiently positive to ensure electrostatic interaction with negatively charged cell walls of pathogens in acidic and slightly (up to pH ~8.5) alkaline solutions. The antimicrobial activity of hybrid microparticles against various pathogens (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans) is comparable with pristine NH2−CNFs. However, a long-timescale use of hybrids ensures the slow and controlled release of Ag+ ions to surrounding media (less than 1.0 wt.-% for one month). Ključne besede: amino-modified cellulose nanofibrils, silver nanoparticles, hybrid microparticles, zeta-potential, antimicrobial activity Objavljeno v DKUM: 09.12.2024; Ogledov: 0; Prenosov: 2
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5. Fluid flow simulation with an ▫$ℋ^2$▫ -accelerated boundary-domain integral methodJan Tibaut, Jure Ravnik, M Schanz, 2024, izvirni znanstveni članek Opis: The development of new numerical methods for fluid flow simulations is challenging but such tools may help to understand flow problems better. Here, the Boundary-Domain Integral Method is applied to simulate laminar fluid flow governed by a dimensionless velocity–vorticity formulation of the Navier–Stokes equation. The Reynolds number is chosen in all examples small enough to ensure laminar flow conditions. The false transient approach is utilized to improve stability. As all boundary element methods, the Boundary-Domain Integral Method has a quadratic complexity. Here, the ℋ2 -methodology is applied to obtain an almost linear complexity. This acceleration technique is not only applied to the boundary only part but more important to the domain related part of the formulation. The application of the ℋ2 -methodology does not allow to use the rigid body method to determine the singular integrals and the integral free term as done until now. It is shown how to apply the technique of Guigiani and Gigante to handle the strongly singular integrals in this application. Further, a parametric study shows the influence of the introduced approximation parameters. For this purpose the example of a lid driven cavity is utilized. The second example demonstrates the performance of the proposed method by simulating the Hagen–Poiseuille flow in a pipe. The third example considers the flow around a rigid cylinder to show the behavior of the method for an unstructured grid. All examples show that the proposed method results in an almost linear complexity as the mathematical analysis promisses. Ključne besede: boundary-domain integral method, velocity–vorticity, adaptive cross approximation, modified helmholtz equation, Yukawa potential, fast multipole method, ℋ-structure Objavljeno v DKUM: 28.11.2024; Ogledov: 0; Prenosov: 7
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6. Assessing energy potential and chemical composition of food waste thermodynamic conversion products: a literature reviewAndreja Škorjanc, Darko Goričanec, Danijela Urbancl, 2024, izvirni znanstveni članek Opis: This study examines the considerable volume of food waste generated annually in Slovenia, which amounted to over 143,000 tons in 2020. The analysis shows that 40% of food waste consists of edible parts, highlighting the potential for reduction through increased consumer awareness and attitudes towards food consumption. The study shows that the consumption phase contributes the most to waste food (46%), followed by primary production (25%) and processing/manufacture (24%). The study addresses various thermodynamic processes, in particular, thermal conversion methods, such as torrefaction pyrolysis and hydrothermal carbonization, which optimize energy potential by reducing the atomic ratio (H/C) and (O/C), thereby increasing calorific value and facilitating the production of solid fuels. The main results show the effectiveness of torrefaction, pyrolysis and hydrothermal carbonization (HTC) in increasing the energy potential of food waste. Ključne besede: energy, thermodynamic conversions, pyrolysis, torrefaction, hydrothermal carbonization, food waste, energy potential, chemical composition Objavljeno v DKUM: 28.08.2024; Ogledov: 53; Prenosov: 8
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7. Solution blow co-spinning of cellulose acetate with poly(ethylene oxide). Structure, morphology, and properties of nanofibersAna Kramar, Thomas Luxbacher, Javier González-Benito, 2023, izvirni znanstveni članek Ključne besede: cellulose acetate, solution blow spinning, co-spinning, zeta potential Objavljeno v DKUM: 09.04.2024; Ogledov: 163; Prenosov: 20
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8. In Vitro Bioelectrochemical Properties of Second-Generation Oxide Nanotubes on Ti–13Zr–13Nb Biomedical AlloyAgnieszka Stróż, Thomas Luxbacher, Karolina Dudek, Bartosz Chmiela, Patrycja Osak, Bożena Łosiewicz, 2023, izvirni znanstveni članek Ključne besede: anodizing, corrosion resistance, oxide nanotubes, Ti–13Zr–13Nb alloy, zeta potential Objavljeno v DKUM: 04.04.2024; Ogledov: 193; Prenosov: 7
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9. Antioxidant activity of different hop (Humulus lupulus L.) genotypesZala Kolenc, Tamara Hribernik, Tomaž Langerholc, Maša Pintarič, Maja Prevolnik Povše, Urban Bren, 2023, izvirni znanstveni članek Opis: The antioxidant activity (AA) of hop extracts obtained from different hop genotypes (n = 14) was studied. For comparison, the purified β-acids-rich fraction and α-acids-with-β-acids-rich fraction were also used to test the antioxidative potential. The AA of purified hydroacetonic hop extracts was investigated using the Ferric Reducing Ability of Plasma (FRAP), Oxygen Radical Absorption Capacity (ORAC) and Intracellular Antioxidant (IA) methods. The FRAP values in different hop genotypes ranged between 63.5 and 101.6 μmol Trolox equivalent (TE)/g dry weight (DW), the ORAC values ranged between 1069 and 1910 μmol TE/g DW and IA potential values ranged between 52.7 and 118.0 mmol TE/g DW. Significant differences in AA between hop genotypes were observed with all three methods. AAs were determined using three different methods, which did not highly correlate with each other. We also did not find significant correlations between AA and different chemical components, which applies both to AA determined using individual methods as well as the total AA. Based on this fact, we assume that the synergistic or antagonistic effects between hop compounds have a more pronounced effect on AA than the presence and quantity of individual hop compounds. Ključne besede: hop, antioxidant activity, FRAP, ORAC, intracellular antioxidative potential, genotypes Objavljeno v DKUM: 20.03.2024; Ogledov: 271; Prenosov: 15
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10. High-resolution spatiotemporal assessment of solar potential from remote sensing data using deep learningMitja Žalik, Domen Mongus, Niko Lukač, 2024, izvirni znanstveni članek Ključne besede: deep learning, fully convolutional neural network, LiDAR data, digital elevation model, solar energy, solar potential Objavljeno v DKUM: 26.01.2024; Ogledov: 244; Prenosov: 8
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