51. Combining mineralisation and thermal modification to improve the fungal durability of selected wood speciesRožle Repič, Andreja Pondelak, Davor Kržišnik, Miha Humar, Andrijana Sever Škapin, 2022, original scientific article Abstract: The development of non-biocidal and environmentally friendly systems to protect wood against biological decay has become a high priority in recent years. In the present study the impact of an innovative modification procedure, combining two environmentally friendly modification methods: thermal modification and mineralisation, using an aqueous solution of calcium acetoacetate as a precursor, on the fungal durability of wood was evaluated. European beechwood (Fagus sylvatica) and Norway sprucewood (Picea abies) were selected as model wood species. Wood samples were treated using either a single or combination of both methods and exposed to four different fungi: Gloeophyllum trabeum, Rhodonia placenta, Trametes versicolor and Pleurotus ostreatus. The effect of the different modifications on moisture content, dynamic vapour sorption, contact angle and pH value was also evaluated. Overall, the highest durability against Rhodonia placenta, Trametes versicolor and Pleurotus ostreatus was achieved through thermal modification in both wood species, while the combination of mineralisation and thermal modification has a synergistic effect against degradation by Gloeophyllum trabeum. In the case of beechwood the mass loss decreased from 41% for native to 6% for combined modified samples. We proved that the effectiveness of different treatment against fungal decay of wood were in strong dependence of their moisture content, dynamic vapour sorption, contact angle and pH values. The role of fungi on the morphology of the wood and on crystal structure of formed carbonate was investigated using SEM-EDS analysis.
Keywords: thermal modification, wood mineralization, fungal durability, environmentally friendly modification methods
Published in DiRROS: 20.06.2023; Views: 340; Downloads: 388
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53. Innovative calcium carbonate-based products to repair cracked cement mortarsMartina Zuena, Andreja Pondelak, Enrico Garbin, Matteo Panizza, Luca Nodari, Andrijana Sever Škapin, Luka Škrlep, Gilberto Artioli, Patrizia Tomasin, 2022, original scientific article Abstract: The durability of Portland cement mortars is often affected by environmental factors, which can cause physicochemical and mechanical degradation processes. In this study, the performance of three products, calcium acetoacetate and calcium tetrahydrofurfuryloxide dissolved in two different solvents developed and tested as stone consolidants, was evaluated in terms of crack filling or sealing and consolidation. Realistic cracks were induced in quasibrittle cement mortar prisms using a custom-designed test rig. The effectiveness and the performance of the considered treatments, investigated on specimens, were evaluated by optical and scanning electron microscopy, colourimetry, water absorption rate, ultrasonic pulse velocity, and surface hardness measurements. Results revealed that, in the examined conditions, the products were more suitable as surface consolidants than as crack fillers.
Keywords: cement mortars, 20th century architecture conservation, calcium acetoacetate, calcium alkoxide, concrete repair, open access
Published in DiRROS: 04.05.2023; Views: 375; Downloads: 212
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54. Mode I fracture of beech-adhesive bondline at three different temperaturesJaka Gašper Pečnik, Andreja Pondelak, Michael David Burnard, Václav Sebera, 2022, original scientific article Abstract: Single edge-notched three-point bending tests (SEN-TPB) for mode I were utilized to experimentallyevaluate fracture properties of adhesive bondlines in European beech (Fagus SylvaticaL.). Thebondline was examined at two anatomical planes with TR and RT orientation and at control andtwo elevated temperatures (70°C and 140°C). Among epoxy (EPI), melamine-urea formaldehyde (MUF), and polyurethane (PUR) adhesives, the highest average critical energyGcwith 0.80 N/mmand fracture energyGfwith 1079.4 N/mm were obtained for EPI in the TR plane and understandard climate conditions (20°C/65% relative humidity), followed by MUF (Gc= 0.50 N/mm andGf= 620 N/mm) and PUR (Gc= 0.25 N/mm andGf= 290.9 N/mm), respectively. PUR was leasteffected by elevated temperature, and no significant differences forGcandGfbetween TR and RTbondline orientations were found for MUF and PUR treated at 20°C/65% relative humidity whilecomparisons between other factors varied significantly. Treatment of specimens at elevatedtemperatures resulted in reduced fracture performance regardless of wood grain orientation orthe adhesive system.
Keywords: crack, fracture, grain orientation, temperature, European Beech, odprti dostop
Published in DiRROS: 03.05.2023; Views: 455; Downloads: 364
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55. Improved synthetic route of incorporation of nanosilicon species into phenol-formaldehyde resin and preparation of novel ZnAl-layered double-hydroxide hybrid phenol-formaldehyde resinAna Dremelj, Romana Cerc Korošec, Andreja Pondelak, Branka Mušič, 2022, original scientific article Abstract: Hybrid phenol-formaldehyde (PF) resins represent one of the most important niche groups of binding systems for composites. New industrial needs, environmental requirements, and price fluctuations have led to further research on materials with enhanced mechanical and thermal properties. The preparation of novel hybrid materials can be achieved by inclusion of various elements or functional groups in the organic polymer phenolic framework. Herein, we report the synthesis and characterization of a PF-based hybrid material with different nanoscale silicone species and ZnAl-layered double hydroxide (LDH). The main goals of this study were to improve the synthetic pathways of hybrid resin, as well as to prepare granulated composite materials and test samples and determine their characterization. Added inorganic species increased the glass-transition temperature by a minimum of 8 °C, which was determined using differential scanning calorimetry (DSC). Rheological properties (melting viscosity and flow distance) of the hybrid resin were measured. The homogeneity of distribution of added species across the organic matrix was evaluated with scanning electron microscopy (SEM). With synthesized new hybrid-binding systems, we prepared different granulated composite materials and evaluated them with the measurements of rheological properties (flow curing characteristics). Tensile strength of samples, prepared from granulated composite material, improved by more than 5%.
Keywords: phenol-formaldehyde hybrid resins, nano-SiO2, ZnAl-LDH, composites, glass-transition temperature, mechanical properties
Published in DiRROS: 03.05.2023; Views: 398; Downloads: 177
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57. Upravljanje prostoživečih živali čezmejnega območja Julijskih Alp na primeru alpskega kozoroga in severnega (alpskega) gamsaAndreja Nève Repe, Andrej Arih, Marco Favalli, Irena Bertoncelj, Aleš Poljanec, 2023, professional article Abstract: Ekološka povezljivost je osnova, ki omogoča naravne procese vrst, kot so pretok genov, selitev, širjenje arealov vrst, in je pomembna za dolgoročno ohranjanje vrst ter njihovih habitatov. Za zagotavljanje ekološke povezljivosti je bistvena fizična povezanost habitatov in enostavno prehajanje osebkov ter vrst med njimi. Ovira za prehajanje organizmov in ohranjanje vrst med državami so razlike v politikah, zakonodaji in upravljanju prostoživečih živali. Neusklajeno upravljanje s prostoživečimi živalmi na obeh straneh državne meje lahko povzroči težave pri povezovanju populacij nekaterih vrst, ker vpliva na gibanje in vedenje živali. Zato so čezmejna zavarovana območja pomembna za zagotavljanje ekološke povezljivosti med dvema državama ali več. Za alpski prostor sta pomembni vrsti alpski kozorog (Capra ibex) in severni (alpski) gams (Rupicapra rupicapra). Zato smo za čezmejno območje Julijskih Alp (velikost 289.660 ha), ki leži med Italijo in Slovenijo, v projektih AlpBioNet2030 in DINALPCONNECT analizirali stanje in upravljanje obeh vrst ter predlagali izboljšave upravljanja s ciljem izboljšati stanje populacij in zagotoviti ekološko povezljivost habitata za vrste na širšem čezmejnem območju. Od leta 2017 smo izpeljali štiri čezmejne delavnice z deležniki z italijanske in slovenske strani (predstavniki lovcev, lastnikov zemljišč, upravljavcev zavarovanih območij, gozdarjev, odločevalcev na nacionalni in regionalni ravni (ministrstva, občine) ter varstva narave). Rezultat participativnega procesa je čezmejni koncept celostnega upravljanja z alpskim kozorogom in severnim (alpskim) gamsom ter njunima habitatoma, ki vsebuje vizijo in strategijo čezmejnega upravljanja ter akcijski načrt na čezmejnem območju Julijskih Alp.
Keywords: ekološka povezljivost, alpski kozorog, severni (alpski) gams, čezmejno upravljanje, Julijske Alpe
Published in DiRROS: 19.04.2023; Views: 547; Downloads: 104
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58. Sušenje jelovih krošenj zaradi gliv povezanih s Pityokteines vorontzowiAna Brglez, Barbara Piškur, Andreja Kavčič, 2023, short scientific article Keywords: gozdovi, varstvo gozdov, bela jelka, Abies alba, Vorontzowov jelov lubadar, Pityokteines vorontzowi, Geosmithia sp.
Published in DiRROS: 24.03.2023; Views: 481; Downloads: 199
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