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42. The role of relative humidity on crystallization of calcium carbonate from calcium acetoacetate precursorAndreja Pondelak, Francesca Rosi, Celeste Maurich, Costanza Miliani, Srečo D. Škapin, Andrijana Sever Škapin, 2019, izvirni znanstveni članek Povzetek: Calcium acetoacetate, Ca(OAcAc)2, was exposed 7, 30 and 365 days to different values of relative humidity (33%, 48%, 75% and 96%) at 40 °C in order to study its transformation to CaCO3. The resulting Ca(OAcAc)2 decomposition and the time dependence of the phase transformations were monitored and critically evaluated by Fourier transform infrared spectroscopy, field emission scanning electron microscopy and X-ray powder diffraction. The impact of relative humidity on CaCO3 polymorph formation was thoroughly assessed. In all of the conditions used and for all ageing periods, the formed crystal structure is found to be vaterite. At the lowest relative humidity (33%), the amorphous CaCO3 remains more or less almost untransformed even after one year of exposure. It is proposed that the reason for the stability of amorphous CaCO3 is due to the limited amount of physisorbed water on the surfaces of the particles, which is considered the driving force for its transformation. However, the carbonation process is faster in the case of the highest humidity (96%). The findings are not only important for better solutions in the field of cultural heritage, but also shed new light on the fundamental mechanism of CaCO3 crystallization.
Ključne besede: calcium acetoacetate, relative humidity, carbonation, amorphous carbonate, vaterite, mechanism
Objavljeno v DiRROS: 22.11.2023; Ogledov: 409; Prenosov: 167
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43. Efficiency of novel photocatalytic coating and consolidants for protection of valuable mineral substratesAndreja Pondelak, Sabina Dolenec, Jonjaua Ranogajec, Luka Škrlep, Snezana B. Vučetić, Vilma Ducman, Andrijana Sever Škapin, 2019, izvirni znanstveni članek Povzetek: In the process of protection and consolidation of valuable materials, the efficiency is the crucial property that needs to be considered. TiO2/ZnAl layered double hydroxide (LDH) coating and silicate- and carbonate-based consolidants were synthesized and proposed to be used for protection and consolidation of four porous mineral substrates: brick, stone, render and mortar. The photocatalytic efficiency of TiO2/ZnAl LDH coating, as well as consolidation efficiency of two consolidants, both applied on model substrates, were studied. The photocatalytic coating showed significant activity and performed well after the durability tests involving rinsing and freezing/thawing procedures. After treatment with both consolidants, a serious enhancement of consolidation of the used substrates was found. On the other hand, the application of TiO2/ZnAl LDH, as well as consolidants, caused negligible changes in the water vapour permeability values and in appearance of the porous mineral substrates, indicating a high level of compatibility.
Ključne besede: photocatalytic coating, consolidant, protection, conservation, porous substrate, cultural heritage
Objavljeno v DiRROS: 21.11.2023; Ogledov: 277; Prenosov: 187
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44. Strižna trdnost spojev z ribjim klejem lepljenega lesa ovrednotena z metodo ABESMatic Sitar, Andreja Pondelak, Samo Grbec, Milan Šernek, 2023, izvirni znanstveni članek Povzetek: V prispevku smo s pomočjo sistema za avtomatizirano vrednotenje zlepljenosti (ABES) ugotavljali razvoj strižne trdnosti ribjega kleja pri lepljenju lesa. Uporabili smo bukov (Fagus sylvatica L.) furnir, ki smo ga lepili pri konstantnem tlaku 12 barov, medtem ko smo spreminjali temperaturo in čas stiskanja. Temperatura je znašala med25 °C in 100 °C, z intervalom 25 °C, čas stiskanja pa od 1 minute do 60 minut. Dosežena maksimalna strižna trdnost je znašala okoli 10 N/mm², dosegli smo jo pri vseh štirih proučevanih temperaturah stiskanja. Na podlagi rezultatov študije smo ugotovili, da strižna trdnost ribjega kleja pri različnih temperaturah segrevanja neenakomerno narašča. Pri višjih temperaturah segrevanja hitreje dosežemo maksimalne strižne trdnosti. Strižne trdnosti spoja lepila iz ribjega kleja smo ugotavljali tudi po standardih EN 204 in EN 205.
Ključne besede: wood
Objavljeno v DiRROS: 14.11.2023; Ogledov: 326; Prenosov: 168
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46. Bolezni, škodljivci in sušni stres pri navadni bukvi v različnih scenarijih podnebnih sprememb (V4-2026) : Aktivnost 2.1: Vzroki hiranja navadne bukve v SlovenijiNikica Ogris, Andreja Kavčič, Janja Zajc, Ana Brglez, Maarten De Groot, Barbara Piškur, 2023, elaborat, predštudija, študija Ključne besede: kompleksna bolezen, škodljiv dejavnik, hiranje, fakultativen patogen, endofit, sušni stres, stresni dejavniki
Objavljeno v DiRROS: 03.11.2023; Ogledov: 398; Prenosov: 94
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48. First record of the northern spruce bark beetle, Ips duplicatus (Sahlberg, 1836), in SloveniaAndreja Kavčič, Zina Devetak, Barbara Piškur, Eva Groznik, Maarten De Groot, 2023, izvirni znanstveni članek Povzetek: The northern spruce bark beetle, Ips duplicatus (Sahlberg), has invaded Central Europe in the past century and continues to spread southwards and westwards. It has caused damage in some parts of Europe in recent decades and poses a serious threat to spruce forests across the continent. From 2018 to 2021, we conducted intensive monitoring to determine the status of I. duplicatus in Slovenia. We used different types of traps and pheromone lures that attract I. duplicatus beetles and took bark samples from bark beetle-infested trees. Of the 26 traps used during the four years of monitoring, I. duplicatus was found in 16 traps in the central part of Slovenia in 2020. Adult beetles were caught in traps containing both I. typographus and I. duplicatus lures. The identity of this species was confirmed using morphological keys and molecular methods. One to five I. duplicatus beetles were found per trap, totaling 25 specimens. However, we did not confirm any I. duplicatus in samples taken from trees in 2021. We conclude that I. duplicatus is present in Slovenia, but our results suggest that the species is only present locally and that the population is small.
Ključne besede: biological invasions, forest pests, temperate forests, conifers, damage, forest pest monitoring, confirmation
Objavljeno v DiRROS: 05.09.2023; Ogledov: 375; Prenosov: 177
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49. A red Roman column from Emona (Ljubljana, Slovenia)Andreja Maver, Bernarda Županek, Maja Gutman, Dragomir Skaberne, Sabina Dolenec, 2020, izvirni znanstveni članek Povzetek: The excavation conducted in 1999 in Ljubljana (Slovenia), in Insula XXVII of the Roman colonia Iulia Emona, un-earthed the remains of a column shaft with an organic core set onto a stone block. The contribution presents this find, its context and likely parallels, the mineralogical-petrographic composition of the stucco, type of the pigments used, as well as the rock of the plinth and its provenance. Of the shaft, only the stucco survives, applied in four mortar layers and painted in red ochre, while its interior surface shows the impressions of reeds. The plinth is a rectangular block made of locally available Lower Jurassic oolitic limestone, presumably from Podpeč. The column may have formed part of a porticus or peristyle, possibly associated with a pool or a bath complex in this part of Late Roman Emona.
Ključne besede: NUK II Site (Ljubljana, Slovenia), columns, Roman architecture, reed impressions, stucco, limestone, Late Roman period
Objavljeno v DiRROS: 04.08.2023; Ogledov: 337; Prenosov: 236
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50. Improving the flame retardancy of wood using an eco-friendly mineralisation processAndreja Pondelak, Andrijana Sever Škapin, Nataša Knez, Friderik Knez, Tomaž Pazlar, 2021, izvirni znanstveni članek Povzetek: A novel environmentally friendly method for in situ formation of CaCO3 deep inside a wood’s structure is presented. The method is based on vacuum-pressure impregnation using a one-component treatment medium – a water solution of calcium acetoacetate - and a single stage process to significantly improve the fire retardancy of the treated material.
Ključne besede: mineralisation, flame retardancy, calcium acetoacetate, calcium carbonate, wood
Objavljeno v DiRROS: 31.07.2023; Ogledov: 346; Prenosov: 237
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