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Povzetek: This study presents the in-situ synthesis of hydroxyapatite (HAp) within the structure of beech and pine wood. The modification process utilized a two-step vacuum-pressure impregnation coupled with chemical precipitation using calcium nitrate tetrahydrate and diammonium hydrogen phosphate solutions, followed by exposure to ammonium hydroxide vapors. While the initial focus was on the overall physicochemical changes, microstructural characteristics and fire behavior of the mineralized wood, the main aim is to specifically investigate the effects of leaching. Because HAp synthesis produces water-soluble ammonium nitrate (NH4NO3) as a by-product, this research systematically addresses how the removal of this component affects the final properties of wood. HAp formation was confirmed by FTIR and X-ray diffraction, while scanning electron microscopy and microcomputed tomography revealed HAp deposits primarily in the cell lumen of both wood species. Fire behavior was evaluated using thermal analysis and the cone calorimeter. The incorporation of non-flammable HAp synthesized within the wood structure may act as a barrier and mass transfer during pyrolysis. This results to comparable or slightly enhanced key fire performance parameters when comparing leached HAp synthesized samples with leached reference samples. In contrast, the unleached HAp synthesized samples, which still contained residual NH4NO3, showed deterioration in fire growth rate (FIGRA) and heat release rate (HRR) parameters, confirming that NH4NO3 acts as an oxidant. However, this oxidative property also leads to improvements in total heat release (THR) and total smoke production (TSP) parameters compared to unleached references, representing a complex interaction when studying the fire properties of mineralized wood.
Ključne besede: chemical precipitation method, fire retardancy, hydroxyapatite, HAp, leaching process, wood
Objavljeno v DiRROS: 17.04.2026; Ogledov: 140; Prenosov: 139
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Povzetek: This study investigates the gel characteristics of alkali-activated materials (AAMs) synthesized using wood ash (WA), and metakaolin (MK) as solid precursors. The research explores the influence of precursor type and sodium hydroxide (NaOH) concentrations in the alkali activator solution on the resulting physicochemical, microstructural, mechanical, and radiological properties of gels. The alkaline activators were prepared by mixing sodium hydroxide solutions (6 M and 12 M) with a sodium silicate (water glass) solution at a volume ratio of 1.5. The physicochemical characteristics of raw materials and AAMs were thoroughly analyzed using X-ray fluorescence (XRF), Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) with EDS elemental mapping. FTIR analysis confirmed the formation of an amorphous gels geopolymer network. XRD revealed the presence of characteristic crystalline phases (quartz, calcite) within an amorphous matrix. Mechanical properties, such as compressive strength, depended on precursor type and alkali molarity: metakaolin (12 M) reached ~14 MPa, while wood ash showed ~4 MPa (6 M) and ~0.5 MPa (12 M) due to high CaO, low Si and Al, and unfavorable SiO2/Al2O3 (5.71) and Na2O/Al2O3 (3.19) ratios. Furthermore, this research estimates radiological doses by quantifying radionuclide content via gamma-spectrometry. Alkali activation significantly reduced radiological haz- ard parameters, with radium equivalent activity (Raeq) decreasing to 238.0 Bq/kg and the external hazard index (Hex) to 0.643 for A12MK, while the annual effective dose rate for A12WA was only 0.265 nSv/y-all values remaining well below the recommended safety limit of 370 Bq/kg (≤1 mSv/y). The decrease in activity concentration index (Iγ), Raeq, and Hex with increasing NaOH concentration indicates effective radionuclide immobilization within the geopolymer matrix, confirming the suitability of these alkali-activated materials for safe use in construction from a radiation protection perspective.
Ključne besede: wood ash, metakaolin, alkali-activated materials, radionuclides
Objavljeno v DiRROS: 24.03.2026; Ogledov: 199; Prenosov: 161
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Povzetek: Understanding wood formation is critical for interpreting tree growth and carbon allocation under changing environmental conditions. While major progress has been made for gymnosperms, harmonized approaches for studying xylogenesis in angiosperms remain limited. Here, we present practical recommendations for observing and analysing xylogenesis in angiosperm trees, illustrated from examples from temperate and sub-Mediterranean forests. The perspective includes guidance on identifying xylem cell types in histological sections, defining developmental phenophases and establishing a workflow for data collection (and analysis). Annotated images are provided to support reproducibility and inter-observer consistency. We also discuss key challenges unique to angiosperms, including cell-type-specificities and wood type differences. Future research priorities include conserving histological images, extending xylogenesis to branches and coarse roots, enabling cross-biome comparisons and advancing kinetic analysis. This framework supports the coordinated expansion of angiosperm xylogenesis studies, enabling deeper insights into tree functioning in a changing world.
Ključne besede: wood formation, xylem cell types, wood type, methodology
Objavljeno v DiRROS: 19.02.2026; Ogledov: 449; Prenosov: 204
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Povzetek: The xylem and phloem anatomy of co-existing tree species provides valuable information on how different tree species face climate change and adjust their vascular structure to local weather conditions. We examined and compared annual ring widths and conduit size in earlywood and early phloem in Fraxinus ornus, Quercus pubescens and Ostrya carpinifolia in a sub-Mediterranean site in the period 2019–2021. The selected xylem and phloem traits were correlated with monthly weather conditions (precipitation and temperature). We found that phloem increment widths and conduits in earlywood and early phloem in the studied tree species showed different trends in terms of interannual variability and in relation to local weather conditions. In F. ornus, May conditions affected xylem traits, while June conditions phloem traits. In Q. pubescens, winter and March precipitation was related to phloem development. In O. carpinifolia, xylem ring width was positively correlated with June precipitation, while early phloem conduits were negatively affected by April temperature. Only two consistent patterns were detected across the species and years studied: wider xylem increments compared to phloem increments, and wider earlywood vessels compared to early phloem sieve tubes. Statistically significant differences were observed among species across all years for the size of xylem and phloem conduits and the hydraulic conductivity of earlywood vessels, which indicates great differences in the calculated hydraulic conductivity among the tree species. To summarize, hydraulic conductivity of earlywood vessels in Q. pubescens was on average for all three years 10.4 -times and 114-times larger than in F. ornus and O. carpinifolia, respectively. High interannual variability and species-specific sensitivity of xylem and phloem traits to precipitation and temperature confirm high plasticity and different radial growth strategies of the studied tree species to ensure optimal functioning under local weather conditions.
Ključne besede: manna ash, pubescent oak, European hop-hornbeam, earlywood, early phloem, wood anatomy, sub-Mediterranean
Objavljeno v DiRROS: 12.02.2026; Ogledov: 633; Prenosov: 263
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Povzetek: The WoodInnovate project addresses pressing challenges facing the forest-wood value chain in the Alps-Adriatic region, which are intensifying due to climate change. Rising temperatures and frequent natural disasters are degrading wood quality and increasing pest outbreaks, particularly from bark beetles. These environmental shifts jeopardize forest ecosystems, reduce the economic viability of timber harvesting, and compromise regional sustainability. WoodInnovate aims to assess and enhance the utilization of storm- and pest-damaged wood through advanced modification techniques, innovative product design, and strategic cross-border collaboration. The project explores climate-resilient tree species and determines optimal uses for lower-grade wood. Stakeholder involvement is essential, including academic institutions, forestry clusters, and industry partners from Italy and Slovenia. Activities include pilot tests, prototype development, knowledge transfer, and regional workshops. The ultimate goal is to transform wood waste from environmental catastrophes into valuable resources, fostering a circular economy and reinforcing forest resilience. The project contributes to climate adaptation strategies while promoting economic revitalization through sustainable material innovation. By enabling cross-sector collaboration, WoodInnovate not only strengthens the forest-wood value chain but also supports EU green objectives, making wood from damaged trees a tool for environmental and social progress.
Ključne besede: climate change, damaged wood, sustainable forest management, innovative wood utilization, cross-border cooperation
Objavljeno v DiRROS: 21.01.2026; Ogledov: 353; Prenosov: 218
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