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1.
Fungal community composition predicts forest carbon storage at a continental scale
Mark A. Anthony, Leho Tedersoo, Bruno De Vos, Luc Croisé, Henning Meesenburg, Markus Wagner, Henning Andreae, Frank Jacob, Paweł Lech, Anna Kowalska, Aleksander Marinšek, 2024, original scientific article

Abstract: Forest soils harbor hyper-diverse microbial communities which fundamentally regulate carbon and nutrient cycling across the globe. Directly testing hypotheses on how microbiome diversity is linked to forest carbon storage has been difficult, due to a lack of paired data on microbiome diversity and in situ observations of forest carbon accumulation and storage. Here, we investigated the relationship between soil microbiomes and forest carbon across 238 forest inventory plots spanning 15 European countries. We show that the composition and diversity of fungal, but not bacterial, species is tightly coupled to both forest biotic conditions and a seven-fold variation in tree growth rates and biomass carbon stocks when controlling for the effects of dominant tree type, climate, and other environmental factors. This linkage is particularly strong for symbiotic endophytic and ectomycorrhizal fungi known to directly facilitate tree growth. Since tree growth rates in this system are closely and positively correlated with belowground soil carbon stocks, we conclude that fungal composition is a strong predictor of overall forest carbon storage across the European continent.
Keywords: fungal community, carbon storage, forest
Published in DiRROS: 19.04.2024; Views: 13; Downloads: 6
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2.
Virome analysis of irrigation water sources provides extensive insights into the diversity and distribution of plant viruses in agroecosystems
Olivera Maksimović, Katarina Bačnik, Mark Paul Selda Rivarez, Ana Vučurović, Nataša Mehle, Maja Ravnikar, Ion Gutiérrez-Aguirre, Denis Kutnjak, 2024, original scientific article

Abstract: Plant viruses pose a significant threat to agriculture. Several are stable outside their hosts, can enter water bodies and remain infective for prolonged periods of time. Even though the quality of irrigation water is of increasing importance in the context of plant health, the presence of plant viruses in irrigation waters is understudied. In this study, we conducted a large-scale high-throughput sequencing (HTS)-based virome analysis of irrigation and surface water sources to obtain complete information about the abundance and diversity of plant viruses in such waters. We detected nucleic acids of plant viruses from 20 families, discovered several novel plant viruses from economically important taxa, like Tobamovirus and observed the influence of the water source on the present virome. By comparing viromes of water and surrounding plants, we observed presence of plant viruses in both compartments, especially in cases of large-scale outbreaks, such as that of tomato mosaic virus. Moreover, we demonstrated that water virome data can extensively inform us about the distribution and diversity of plant viruses for which only limited information is available from plants. Overall, the results of the study provided extensive insights into the virome of irrigation waters from the perspective of plant health. It also suggested that an HTS-based water virome surveillance system could be used to detect potential plant disease outbreaks and to survey the distribution and diversity of plant viruses in the ecosystem.
Keywords: plant viruses, environmental water testing, high-throughput sequencing, agroecosystems, irrigation water, virome
Published in DiRROS: 29.03.2024; Views: 95; Downloads: 42
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3.
4.
Evaluation of fly ash-based alkali activated foams at room and elevated temperatures
Katja Traven, Mark Češnovar, Srečo D. Škapin, Vilma Ducman, 2020, published scientific conference contribution

Abstract: Alkali activated materials (AAM) are, in their broadest classification, any binder systems derived by the reaction of an alkali metal source (silicates, alkali hydroxides, carbonates , sulphates) with a solid, amorphous alumosilicate powder (found in precursors such as slag, fly ash and bottom ash). A wide variety of products can be obtained by the alkali activation process and could replace traditional construction products. Among the se, alkali activated foams (AAF) represent one of the most promising materials, owing to their economically accessible alumosilicate rich source materials, including industrial waste materials, clean processing, higher added value and most importantly, pro ducts with competitive properties. In the present study, the properties of alkali activated fly ash - based foam materials were studied at room temperature as well as at elevated temperatures (up to 1200 °C ) in order to develop a durable material in terms o f mechanical properties and suitability for high temperature applications.
Keywords: lightweight porous insulating material, alkali activated materials, microstructural analysis
Published in DiRROS: 05.03.2024; Views: 103; Downloads: 42
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5.
The deformation of alkali-activated materials at different curing temperatures
Mark Češnovar, Katja Traven, Vilma Ducman, 2020, published scientific conference contribution

Abstract: Alkali activation is a chemical process whereby materials rich in aluminosilicate, which dissolves in basic media at room temperature, form binding phases by polycondensation. The alkali- activated materials (AAM) are a promising alternative to binding materials such as cement or other products in civil engineering (van Deventer et al., 2012). This study investigates the early age shrinkage behavior of Slovenian ladle and electric arc furnace slag - based alkali activated materials at different curing temperatures. The dimensions of specimens cured at room temperature and elevated temperatures up to 90 °C were measured over the first 7 hours (every 10 min). The results show that the most shrinkage occurred at the highest temperature, owing to the highest rate of evaporation of liquid content. Loss of mass follows from the drying shrinkage.
Keywords: alkali activated materials, shrinkage, compressive strength
Published in DiRROS: 01.03.2024; Views: 104; Downloads: 71
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6.
Kompoziti iz skorje: nova gozdarsko-lesarska vrednostna veriga
Sergej Medved, Grega Vilman, Urban Tajher, Mark Sever, Alan Antonović, 2023, original scientific article

Abstract: Skorja je večopravilni (večfunkcijski) material, saj deluje kot zaščita (pred fizikalnimi in mehanskimi poškodbami, pa tudi pred biološko razgradnjo), omogoča transport vode in plinov, občasno pomaga pri fotosintezi in nudi podporo drevesu. Skorje je od 10 % do 20 % celotne mase drevesa, vendar je znaten delež ostane neizkoriščen. Da bi prikazali možnosti rabe skorje za izdelavo različnih kompozitov, smo izdelali in analizirali tri različne kompozite, in sicer lesno-plastični kompozit iz skorje in polietilena, trislojni ploščni kompozit iz skorje, zlepljene z melamin-urea-formaldehidnim lepilom, in enoslojni ploščni kompozit iz vlažnih iveri skorje, zlepljenih s taninskimi lepili.
Keywords: skorja, iveri, lesno plastični kompozit, iverna plošča
Published in DiRROS: 29.02.2024; Views: 171; Downloads: 38
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7.
The influence of different fibres quantity on mechanical and microstructural properties of alkali-activated foams
Katja Traven, Mark Češnovar, Barbara Horvat, Vilma Ducman, 2022, published scientific conference contribution

Abstract: Alkali activated foams (AAFs) were produced using electric arc furnace steel slag (EAF) and ladle furnace basic slag (LS), obtained from two metallurgical companies in Slovenia. They were activated with a mixture of sodium water glass (Na2SiO3) and solid NaOH and foamed with hydrogen peroxide (H2O2). Pores were stabilized with the addition of Triton as a surfactant. Four types of fibres were added to the studied mixture (polypropylene (PP), polyvinyl-alcohol (PVA), basalt (B), and glass wool (GW)) in five different quantities: 0.5, 1.0, 1.25, 1.5 and 2.0 vol % in order to additionally stabilize the structure and thus improve its mechanical properties. The results of mechanical properties showed, that compressive strength was increased in all 20 specimens, partially due to the increased density as well as to the fibre addition. Flexural strength on the other hand was the most improved in the samples where PP and PVA fibres were added. The samples with the addition of B and GW fibres on the other hand showed only small or no improvement in flexural strength in comparison to the referenced sample. Additionally, the microstructure of used fibres and selected foams was also investigated by the means of SEM analysis.
Keywords: fibers, alkali activated foams, properties
Published in DiRROS: 31.01.2024; Views: 146; Downloads: 56
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8.
Influence of homogenization of alkali-activated slurry on mechanical strength
Barbara Horvat, Mark Češnovar, Katja Traven, Majda Pavlin, Katja Koenig, Vilma Ducman, 2022, published scientific conference contribution

Abstract: Alkali-activated materials are promising materials for the construction industry due to the accessibility of the precursors, which are mainly secondary industrial by-products, and their cost- effective and energy-efficient production. Although these materials are not new, some of the parameters in the technological process are not yet fully understood and tested. Therefore, in this paper in the means of mechanical strength, the preparation of alkali-activated pastes by using a three-roll mill homogenization method is discussed. The influence of homogenization of alkali- activated slurry has been evaluated on different waste materials (fly ash, fly ash with metakaolin, slag mixture (electric arc furnace slag and ladle slag), glass wool, waste green ceramics), which are treated with different alkali activators (NaOH, commercial sodium silicate solution, laboratory-produced alkali activators based on waste cathode- ray tube glass) with different curing regimes (60 °C and 70 °C) and different drying methods (drying at room temperature, drying at 105 °C). The viscosity of the slurry before homogenization was higher than after homogenization, the distribution of elements was more uniform and the compressive strength higher in all homogenized alkali activated materials, regardless of other parameters.
Keywords: secondary raw material, alkali activated material, foaming, homogenization, mechanical strength
Published in DiRROS: 21.12.2023; Views: 227; Downloads: 73
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9.
Particle size manipulation as an influential parameter in the development of mechanical properties in electric arc furnace slag-based AAM
Katja Traven, Mark Češnovar, Vilma Ducman, 2019, original scientific article

Abstract: Alkali-activated materials (AAM) have gained recognition as a promising alternative to technical ceramic and building materials owing to the lower energy demands for production and the potential to use slag as a precursor. In the present study, five sets of slag-based AAM pastes were prepared with different particle sizes (fractions d < 63, 63 < d < 90, and 90 < d < 125 μm in different mass ratios) under the same curing regime and using a fixed precursor to activator (water) mass ratio. Precursors and the hardened AAM are evaluated using BET, XRD, XRF, SEM, FTIR, reactivity of precursors by leaching, and mercury intrusion porosimetry (MIP). Chemical analysis indicated only marginal differences among the different-sized fractions of input materials, whereas the BET surface area and reactivity among the precursors differed significantly-smaller particles had the largest surface area, and thus, higher reactivity. The mineralogical differences between the precursors and hardened AAM were negligible. The results revealed that compressive strength was significantly influenced by particle size, i.e., a threefold increase in strength when the particle size was halved. Microstructural evaluation using MIP confirmed that the porosity was the lowest in AAM with the smallest particle size. The low porosity and high reactivity of the fine fractions led to the highest compressive strength, confirming that manipulation of particle size can significantly influence the mechanical properties.
Keywords: alkalijsko aktivirani materiali, žlindra iz obločne peči, mehanska aktivacija, mehanske lastnosti, poroznost, alkali-activated materials (AAM), electric arc furnace steel slag, mechanical activation, mechanical properties, porosity
Published in DiRROS: 22.11.2023; Views: 247; Downloads: 128
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10.
The potential of ladle slag and electric arc furnace slag use in synthesizing alkali activated materials; the influence of curing on mechanical properties
Mark Češnovar, Katja Traven, Barbara Horvat, Vilma Ducman, 2019, original scientific article

Abstract: Alkali activation is studied as a potential technology to produce a group of high performance building materials from industrial residues such as metallurgical slag. Namely, slags containing aluminate and silicate form a useful solid material when activated by an alkaline solution. The alkali-activated (AA) slag-based materials are promising alternative products for civil engineering sector and industrial purposes. In the present study the locally available electric arc furnace steel slag (Slag A) and the ladle furnace basic slag (Slag R) from different metallurgical industries in Slovenia were selected for alkali activation because of promising amorphous Al/Si rich content. Different mixtures of selected precursors were prepared in the Slag A/Slag R ratios 1/0, 3/1, 1/1, 1/3 and 0/1 and further activated with potassium silicate using an activator to slag ratio of 1:2 in order to select the optimal composition with respect to their mechanical properties. Bending strength of investigated samples ranged between 4 and 18 MPa, whereas compressive strength varied between 30 and 60 MPa. The optimal mixture (Slag A/Slag R = 1/1) was further used to study strength development under the influence of different curing temperatures at room temperature (R. T.), and in a heat-chamber at 50, 70 and 90 °C, and the effects of curing time for 1, 3, 7 and 28 days was furthermore studied. The influence of curing time at room temperature on the mechanical strength at an early age was found to be nearly linear. Further, it was shown that specimens cured at 70 °C for 3 days attained almost identical (bending/compressive) strength to those cured at room temperature for 28 days. Additionally, microstructure evaluation of input materials and samples cured under different conditions was performed by means of XRD, FTIR, SEM and mercury intrusion porosimetry (MIP).
Keywords: alkali activation, slag, influence of curing regime, FTIR
Published in DiRROS: 13.09.2023; Views: 244; Downloads: 133
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