Publications by authors named "Joris Van Acker"

Purpose: This study aimed to evaluate the accuracy of detecting vertical root fractures in Biodentine™-filled teeth using the Promax 3Dmax cone-beam computed tomography (CBCT) unit compared to periapical radiographs. It tested hypotheses regarding CBCT's diagnostic superiority in non-root-filled and Biodentine™-root-filled maxillary central incisors and assessed the impact of smaller field of view and lower intensity settings on detection accuracy.

Materials And Methods: Extracted maxillary incisors were divided into groups based on fracture status and root filling material, then placed in a Thiel-embalmed skull to simulate clinical conditions.

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Article Synopsis
  • African bistable savannas are rich in biodiversity and require conservation efforts.
  • Forest restoration through natural regeneration, rather than human intervention like burning or planting, can enhance biodiversity and carbon stocks.
  • The decision to restore forests or protect savannas should be based on a deep understanding of the local environment and its specific needs.
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  • A significant portion of potential global forest restoration lies in unstable mesic savannas in Africa, which can enhance carbon and biodiversity if protected from human-induced fires.
  • A study in the Democratic Republic of the Congo found that aboveground carbon recovery in an 88-ha savanna patch took about 17 years, with a long-term estimate suggesting up to 112 years to reach near old-growth forest carbon levels.
  • While species richness improved to 33.17% after 17 years, achieving full recovery of both species richness and composition may take 54 and 124 years, respectively, highlighting the need for ongoing monitoring and consideration of socio-economic and climate variability.
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Common beech (Fagus sylvatica) is one of the most important deciduous tree species in European forests. However, climate-change-induced drought may threaten its dominant position. The Sonian Forest close to Brussels (Belgium) is home to some of the largest beech trees in the world.

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Background And Aims: Heartwood plays an important role in maintaining the structural integrity of trees. Although its formation has long been thought to be driven solely by internal ageing processes, more recent hypotheses suggest that heartwood formation acts as a regulator of the tree water balance by modulating the quantity of sapwood. Testing both hypotheses would shed light on the potential ecophysiological nature of heartwood formation, a very common process in trees.

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Wood identification is a key step in the enforcement of laws and regulations aimed at combatting illegal timber trade. Robust wood identification tools, capable of distinguishing a large number of timbers, depend on a solid database of reference material. Reference material for wood identification is typically curated in botanical collections dedicated to wood consisting of samples of secondary xylem of lignified plants.

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The potential of whole genome duplication to increase plant biomass yield is well-known. In Arabidopsis tetraploids, an increase in biomass yield was accompanied by a reduction in lignin content and, as a result, a higher saccharification efficiency was achieved compared with diploid controls. Here, we evaluated whether the results obtained in Arabidopsis could be translated into poplar and whether the enhanced saccharification yield upon alkaline pretreatment of hairpin-downregulated () transgenic poplar could be further improved upon a whole genome duplication.

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The distribution and good spreading of adhesive resins is critical for the wood-based panels industry. Full 3D non-destructive characterization is necessary, but methods are limited due to the chemical similarities between the resins and the wood fibers. For X-ray microtomography ([Formula: see text]CT), the doping of the resin with a highly attenuating contrast agent is necessary to visualize the resin distribution.

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Moisture performance is an important factor determining the resistance of wood-based building materials against fungal decay. Understanding how material porosity and chemistry affect moisture performance is necessary for their efficient use, as well as for product optimisation. In this study, three complementary techniques (X-ray computed tomography, infrared and low-field NMR spectroscopy) are applied to elucidate the influence of additives, manufacturing process and material structure on the liquid water absorption and desorption behaviour of a selection of wood-based panels, thermally modified wood and wood fibre insulation materials.

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Background: The identification of tropical African wood species based on microscopic imagery is a challenging problem due to the heterogeneous nature of the composition of wood combined with the vast number of candidate species. Image classification methods that rely on machine learning can facilitate this identification, provided that sufficient training material is available. Despite the fact that the three main anatomical sections contain information that is relevant for species identification, current methods only rely on transverse sections.

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Long-term poplar phytoremediation data are lacking, especially for ecosystem services throughout rotations. We tested for rotation-age differences in biomass productivity and carbon storage of clones Bartr. ex Marsh × L.

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Traditionally, fungal growth dynamics were assessed manually, limiting the research to a few environmental conditions and/or fungal species. Fortunately, more automated ways of measurement are gaining momentum due to the availability of cheap imaging and processing equipment and the development of dedicated image analysis algorithms. In this paper, we use image analysis to assess the impact of environmental conditions on the growth dynamics of two economically important fungal species, and .

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Background And Aims: Tree rings, as archives of the past and biosensors of the present, offer unique opportunities to study influences of the fluctuating environment over decades to centuries. As such, tree-ring-based wood traits are capital input for global vegetation models. To contribute to earth system sciences, however, sufficient spatial coverage is required of detailed individual-based measurements, necessitating large amounts of data.

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Maintaining xylem water transport under drought is vital for plants, but xylem failure does occur when drought-induced embolisms form and progressively spread through the xylem. The hydraulic method is widely considered the gold standard to quantify drought-induced xylem embolism. The method determines hydraulic conductivity (Kh) in cut branch samples, dehydrated to specific drought levels, by pushing water through them.

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Background And Aims: Wood traits are increasingly being used to document tree performance. In the Congo Basin, however, weaker seasonality causes asynchrony of wood traits between trees. Here, we monitor growth and phenology data to date the formation of traits.

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Article Synopsis
  • Understanding how forests store carbon is important for climate change!
  • Scientists studied the age of carbon in different parts of African tropical forests and found that smaller understory trees hold carbon longer than taller trees!
  • This means we need to pay more attention to all parts of the forest for better conservation and carbon tracking!
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Purpose: Droughts are expected to become more intense and frequent. Mixed forests can be more resilient to extreme events, but are the individual trees in mixed forests also more resilient to drought?

Methods: We sampled 275 trees in 53 temperate forest stands in northern Belgium: monocultures, two-species mixtures, and the three-species mixture of Fagus sylvatica, Quercus robur, and Q. rubra.

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A better understanding and prediction of the impact of changing climate on tree stem growth could greatly benefit from the combination of anatomical and ecophysiological knowledge, yet the majority of studies focus on one research field only. We propose an approach that combines the method of pinning (cambial wounding) to timestamp anatomical X-ray computed microtomography images with continuous measurements of sap flow and stem diameter variations. By pinning the cambium of well-watered and drought-treated young African tropical trees of the species Maesopsis eminii Engl.

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Injectable composites for tissue regeneration can be developed by dispersion of inorganic microparticles and cells in a hydrogel phase. In this study, multifunctional carbonate microparticles containing different amounts of calcium, magnesium and zinc were mixed with solutions of gellan gum (GG), an anionic polysaccharide, to form injectable hydrogel-microparticle composites, containing Zn, Ca and Mg. Zn and Ca were incorporated into microparticle preparations to a greater extent than Mg.

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The North American wood decking market mostly relies on easily treatable Southern yellow pine (SYP), which is being impregnated with micronized copper (MC) wood preservatives since 2006. These formulations are composed of copper (Cu) carbonate particles (CuCO3·Cu(OH)2), with sizes ranging from 1 nm to 250 μm, according to manufacturers. MC-treated SYP wood is protected against decay by solubilized Cu2+ ions and unreacted CuCO3·Cu(OH)2 particles that successively release Cu2+ ions (reservoir effect).

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Hydrogels offer several advantages as biomaterials for bone regeneration, including ease of incorporation of soluble substances such as mineralization-promoting enzymes and antibacterial agents. Mineralization with calcium phosphate (CaP) increases bioactivity, while antibacterial activity reduces the risk of infection. Here, gellan gum (GG) hydrogels were enriched with alkaline phosphatase (ALP) and/or Seanol(®), a seaweed extract rich in phlorotannins (brown algae-derived polyphenols), to induce mineralization with CaP and increase antibacterial activity, respectively.

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Background And Aims: Disentangling tree growth requires more than ring width data only. Densitometry is considered a valuable proxy, yet laborious wood sample preparation and lack of dedicated software limit the widespread use of density profiling for tree ring analysis. An X-ray computed tomography-based toolchain of tree increment cores is presented, which results in profile data sets suitable for visual exploration as well as density-based pattern matching.

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Context: Wood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood specific gravity varies widely among and within species and also within individual trees.

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The impact of Holocene drought events on the presumably stable Central African rainforest remains largely unexplored, in particular the significance of fire. High-quality sedimentary archives are scarce, and palynological records mostly integrate over large regional scales subject to different fire regimes. Here, we demonstrate a direct temporal link between Holocene droughts, palaeofire and vegetation change within present-day Central African rainforest, using records of identified charcoal fragments extracted from soil in the southern Mayumbe forest (Democratic Republic of Congo).

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In the Neotropics, the genus Hydrangea of the popular ornamental hortensia family is represented by climbing species that strongly cling to their support surface by means of adhesive roots closely positioned along specialized anchoring stems. These root-climbing hortensia species belong to the nearly exclusive American Hydrangea section Cornidia and generally are long lianescent climbers that mostly flower and fructify high in the host tree canopy. The Mexican species Hydrangea seemannii, however, encompasses not only long lianescent climbers of large vertical rock walls and coniferous trees, but also short 'shrub-like' climbers on small rounded boulders.

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