1. Random walks and the electronic structure of grapheneNino Bašić, Patrick W. Fowler, Barry T. Pickup, Primož Potočnik, 2026, izvirni znanstveni članek Opis: Results from the mathematical literature on random walks reveal a closed-form analytical expression for the ▫$\pi$▫-energy and bond number of graphene in the simplest tight-binding model and its Hartree-Fock Hubbard extension. Closed-form expressions follow for all ▫$\pi$▫ spectral moments of graphene. Bond numbers of carbon and boron nitride (BN) zigzag nanotubes are found as finite sums, with graphene and hexagonal boron nitride sheets as asymptotes.
Ključne besede: graph theory, random walks, graphene, bond number, tight-binding model, spectral moments, Hubbard model, zigzag nanotubes, hexagonal boron nitride, gamma function
Objavljeno v RUP: 10.03.2026; Ogledov: 73; Prenosov: 6
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3. An Isogeometric Tearing and Interconnecting (IETI) method for solving high order partial differential equations over planar multi-patch geometriesMario Kapl, Aljaž Kosmač, Vito Vitrih, 2026, izvirni znanstveni članek Opis: We present a novel method for solving high-order partial differential equations (PDEs) over planar multi-patch geometries with
possibly extraordinary vertices demonstrated on the basis of the polyharmonic equation of order m, m ≥ 1, which is a particular linear elliptic PDE of order 2m. Our approach is based on the concept of Isogeometric Tearing and Interconnecting (IETI) and allows to couple the numerical solution of the PDE with Cs-smoothness, , across the edges of the multi-patch geometry. The proposed technique relies on the use of a particular class of multi-patch geometries, called bilinear-like Gs multi-patch parameterizations, to represent the multi-patch domain. The coupling between the neighboring patches is done via the use of Lagrange multipliers and leads to a saddle point problem, which can be solved first by a small dual problem for a subset of the Lagrange multipliers followed by local, parallelizable problems on the single patches for the coefficients of the numerical solution. Several numerical examples for the polyharmonic equation of order m = 1, m = 2 and m = 3, i.e. for the Poisson’s, the biharmonic and the triharmonic equation, respectively, are shown to demonstrate the potential of our IETI method for solving high-order problems over planar multi-patch geometries with possibly extraordinary vertices.
Ključne besede: isogeometric analysis, Galerkin method, C^s-smoothness, Tearing and Interconnecting, multi-patch domain, polyharmonic equation
Objavljeno v RUP: 02.02.2026; Ogledov: 260; Prenosov: 4
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4. Moisture-activated set-recovery of thermo-hydro-mechanically densified hardwood dowels for high-tolerance timber connectionsLei Han, Alexander Scharf, Mohammad Derikvand, Matthew Schwarzkopf, Bogdan Mitkovski, Dick Sandberg, Andreja Kutnar, 2026, izvirni znanstveni članek Opis: Conventional wooden dowel connections in timber structures rely on tight press-fit installation, which requires high insertion forces and often loosens over time due to stress relaxation. This study investigates an alternative approach that exploits the moisture-activated set-recovery of thermo-hydro-mechanically (THM) densified hardwood dowels to enable slip-fit assembly followed by self-tightening in service. To this end, European beech and black poplar were densified radially and tangentially at different compression ratios. They were then evaluated for swelling kinetics, swelling pressure, bending performance, and moisture-activated expansion using in-situ X-ray CT in water at 20 °C and 100 °C. Results show that activation kinetics can be controlled by temperature. Expansion was rapid within minutes in hot water and slower but equivalent in magnitude at room temperature. Beech outperformed poplar, with radial densification at 35 % compression ratio producing a peak swelling pressure of 5.7 MPa and a modulus of rupture of 268 MPa after activation. Poplar generated higher free expansion but significantly lower pressure due to its lower stiffness. Radial densification was consistently more effective than tangential, enhancing both expansion magnitude and pressure generation. Capillary uptake triggered expansion along the dowel length (∼30 mm in 1 h) and produced an elliptical expansion profile. Importantly, mechanical strength was retained post-activation, which confirms structural suitability. These results demonstrate that THM-densified beech dowels can offer a robust self-tightening mechanism, combining low-force installation with durable pressure generation and stable mechanical performance. This provides a viable path toward adhesive-free, metal-free, high-tolerance timber connections.
Ključne besede: THM densification, dowel laminated timber, CT scanning
Objavljeno v RUP: 28.01.2026; Ogledov: 279; Prenosov: 0
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5. Responsible reporting on suicide in Slovenia : are we there yet?Vanja Gomboc, Diego De Leo, Vita Poštuvan, 2025, izvirni znanstveni članek Opis: Exposure to media reporting on suicide can be both a risk and a protective factor, as (ir)responsible reporting on suicide can have different effects on vulnerable people. Since online media are increasingly important in everyday life, this study aimed to examine how the three most widely read Slovenian online media report on suicide. 114 online media articles published between 1 January and 31 December 2017 were included in the study and assessed for compliance with recommendations on responsible media reporting on suicide, and inclusion of harmful and protective characteristics. Different articles included or adhered to different recommendations, and harmful and protective characteristics. The correlation between compliance with recommendations, and the inclusion of protective and harmful characteristics suggests that although articles comply with recommendations, they do not necessarily contain enough protective information. The study confirms patterns observed in other studies while providing a first insight into Slovenian online media reporting on suicide. Further research is needed to confirm our findings while considering different online media. Additionally, future studies should focus on other aspects of reporting on suicide, e.g., comments under online media articles, which might also impact readers.
Ključne besede: media, suicide, reporting
Objavljeno v RUP: 16.01.2026; Ogledov: 220; Prenosov: 2
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6. Thermal energy storage and leakage prevention of phase change materials via one-step impregnation and in-situ polymerization process in hardwoodJakub Grzybek, Gabriel Zsembinszki, Emiliano Borri, Alina Meindl, Zuzana Paschová, Alexander Petutschnigg, Luisa F. Cabeza, Thomas Schnabel, 2026, izvirni znanstveni članek Opis: Wood is a versatile material widely used in building construction, but its low thermal mass limits its ability to regulate indoor temperatures and mitigate thermal load peaks. Phase change materials are effective at storing thermal energy, but when impregnated into wood, they leak out, compromising performance and restricting their use in buildings. This study introduces a novel one-step impregnation process combined with in-situ polymerization using furfuryl alcohol and a capric-stearic acid phase change material mixture to create a sustainable material for thermal energy storage. Various formulations were tested on European beech (Fagus sylvatica L.) to evaluate effectiveness of the approach. The results confirm that this method successfully prevents phase change material leakage. Moreover, differential scanning calorimetry and nuclear magnetic resonance verified that phase change materials retain their thermal energy storage functionality, with no chemical cross-linking between the phase change materials and furfuryl alcohol. The treated wood showed up to 185 % higher thermal energy storage capacity, enhanced dimensional stability (anti-swelling efficiency up to 87 %), and 28 % higher compressive strength than untreated wood. It is a step towards sustainable, multifunctional, leakage-free, enhanced mechanical properties, improved dimensional stability wood for thermal energy storage for building applications, with potential for further optimisation and characterisation.
Ključne besede: bio-based materials, fatty acid, furfuryl alcohol, sustainable building materials, wood modification, phase change materials
Objavljeno v RUP: 09.01.2026; Ogledov: 271; Prenosov: 9
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7. Hierarchical pore engineering of lignocellulose-based carbon materials for electric double-layer capacitorsYanyu Li, Huyan Shen, Yiyan Zhu, Imran Zada, Fang Song, Qinglei Liu, Hui Pan, Shenmin Zhu, Juan Li, Bohumil Kasal, 2025, pregledni znanstveni članek Opis: Lignocellulose is an ideal precursor for supercapacitor electrodes due to its diverse structures and abundant availability. For supercapacitors, particularly electric double-layer capacitors (EDLCs), pore structure is critical. This review summarizes advances in lignocellulose-derived hierarchical porous carbon (LHPC) for supercapacitors, focusing on pore structure and future research directions. We discuss how pore structure influences supercapacitor performance, the activation methods for creating pores in LHPC, and review studies on optimizing pore structure for high-performance supercapacitors. Hierarchical porous carbon should feature a sufficient micropore surface area along with suitable mesoporous and macroporous surfaces to enhance rate performance while maintaining capacitance. This review is expected to actively advance the selection of lignocellulosic precursors and the development of optimized pore structure models, with the ultimate goal of enabling efficient production of lignocellulose-derived hierarchical porous carbon electrodes with superior properties.
Ključne besede: lignocellulose, performance, carbon
Objavljeno v RUP: 29.12.2025; Ogledov: 272; Prenosov: 2
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8. Flexural behavior of adhesively bonded cross-laminated timber-concrete composite (TCC) panel with glass-fiber textile mesh as reinforcement in concrete : experimental studying and numerical simulationHaoze Chen, Wenzhuo Ma, Bohumil Kasal, Wei Yang, Libo Yan, 2025, izvirni znanstveni članek Opis: Timber-concrete composite (TCC) structures offer higher stiffness and loading capacity compared to pure timber structures with similar dimensions. A more rigid adhesive interface between concrete and timber offers advantages over conventional connections (e.g., mechanical fasteners and notches) by ensuring strain compatibility between the two materials. Fiber-based textiles, such as alkali-resistant (AR) glass fiber fabric, provide electrochemical corrosion resistance when used as reinforcement in concrete. An innovative composite floor system was introduced in this study, comprising cross-laminated timber (CLT) and reinforced concrete embedded with lightweight AR glass textile reinforcement, rigidly bonded together through epoxy adhesive bonding. A comprehensive investigation on the flexural behavior of this composite structure panel was conducted. Instrumentation, like digital image correlation (DIC) and optical fiber sensors, was employed to record strain distribution and development during four-point bending tests on those panels. A nonlinear numerical model was developed to predict the flexural behavior of the panels using continuum damage evolution for timber, concrete damage plasticity (CDP) model, and cohesive contact behavior between timber layers, considering the non-glue edge in the transverse layer. Experimental results showed that the failure predominantly occurred in the transverse layer of the CLT in the TCC panels. Employing glass fabric reinforcement within the CLT-constituted TCC led to an increase in loading bearing capacity. Numerical simulation indicated that textile reinforcement embedded within TCC's concrete counteracted localized concrete tensile failure, preserving structural integrity, delaying cohesive failure between planks in CLT, and consequently amplifying ultimate loading capacity of TCC structure.
Ključne besede: CLT, TCC, adhesive bonding
Objavljeno v RUP: 23.12.2025; Ogledov: 318; Prenosov: 2
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9. Long-term durability of flax-glass hybrid FRP-timber composite structures subjected to hygrothermal environment : experimental and simulationSilu Huang, Libo Yan, Bohumil Kasal, Wei Yang, 2025, izvirni znanstveni članek Opis: This paper focuses on the experimental and numerical analysis of long-term performance of flax-glass hybrid FRP (HFRP)-laminated veneer lumber (LVL) joints and beams subjected to hygrothermal environment (50℃ and 95 %RH) for six months. The joints and beams with different fibre fabric stacking sequences of HFRP exposed at different exposure intervals (0, 1, 2, 3 and 6 months) were tested under block shear and four-point bending, respectively. The tensile properties of epoxy and HFRP composites under those exposure intervals were also examined to explore degradation mechanisms of HFRP in LVL-HFRP beams. Tensile strength and strain of HFRP showed a major reduction (26.7 – 32.1 %) in the first month of exposure. Hydrolysis and oxidation of epoxy were found to have insignificant effects on HFRP tensile properties, based on Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results. A significant decrease (34.7 – 35.7 %) of LVL-HFRP joints in their shear strength was attributed to weakened hydrogen bonds between cellulose and lignin-hemicellulose matrix, along with the degradation and softening of hemicellulose. LVL-GF beams in which the glass fibre layer of HFRP was adhered to LVL exhibited a major reduction in bending strength (23.4 %) after the first month of exposure. In LVL-FG beams where the flax fibre layer was adhered to LVL, a major decrease in bending strength (25.8 %) was observed after two-month exposure. The postponed reduction in LVL-FG beams compared with LVL-GF beams was caused by the slower moisture diffusion in HFRP of LVL-FG beams than that in LVL-GF beams. A diffusion–stress coupled finite element (FE) model was developed, incorporating moisture diffusion and moisture-dependent mechanical properties for both the timber and HFRP components. Based on this model, the flexural response of LVL–HFRP beams after hygrothermal exposure was simulated, showing satisfactory agreement with experimental results. This research developed a step towards the long-term performance evaluation of HFRP-timber composite structures with different fabric stacking sequences of HFRP.
Ključne besede: long-term durability, hybrid FRP, timber-hybrid FRP composite structure
Objavljeno v RUP: 23.12.2025; Ogledov: 308; Prenosov: 3
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10. Optimized mix design and fire resistance of geopolymer recycled aggregate concrete under elevated temperaturesBright Asante, Bo Wang, Libo Yan, Bohumil Kasal, 2025, izvirni znanstveni članek Opis: This study investigates the performance of fly ash-based geopolymer recycled aggregate concrete (GRAC) as a sustainable alternative to Ordinary Portland Cement (OPC) concrete, focusing on its compressive strength and behavior under high-temperature exposure (150 °C, 300 °C, 600 °C, and 900 °C). The research emphasizes the use of 100 % recycled concrete aggregates as a replacement for natural aggregates, with samples cured at ambient conditions and at 60 °C in an oven. Key factors, including water content and curing conditions, were evaluated to determine their influence on compressive strength and thermal stability. Results indicate that water content is the primary factor governing compressive strength, while recycled aggregates contribute to a secondary but notable effect. GRAC maintained up to 65 % of its initial strength after exposure to 600 °C, though strength degradation and severe cracking occurred at 900 °C. Oven-cured samples showed fewer surface cracks but experienced slightly higher mass loss than room-cured counterparts. This study highlights the potential of GRAC as an environmentally friendly material capable of withstanding moderate thermal conditions, providing significant contributions to green construction practices and the reuse of construction and demolition waste.
Ključne besede: geopolymer, recycled aggregate concrete, elevated temperature
Objavljeno v RUP: 23.12.2025; Ogledov: 281; Prenosov: 2
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