3D Experimental investigation of the hygro-mechanical behaviour of wood at cellular and sub-cellular scale: detection of local deformations

The swelling/shrinkage of spruce wood samples (Picea Abies) is documented with high resolution XRay Tomography and advanced image analysis tools. We report the reversible moisture-induced global and local deformations at the cellular and sub-cellular scales. In particular, we present sophisticated methods for detecting local deformations in the cell wall. Insight is given on the hygromechanical behaviour of wood cell material and on the role of ultra-cellular components in wood, such as bordered pits and rays

In situ, in vitro and in silico analysis of coating performance

Service life prediction (SLP) is a complex yet essential method for analysing coating performance. Accurate and precise assessment is crucial for a strong position on the market. Correct knowledge of the critical failure points, maintenance/replacement frequency and related costs are part of this approach. This paper describes the scale-dependent tools within a bio-engineering framework that are applied for coating research, ranging from modelling, X-ray tomography, lab testing, controlled fungal infestation up to continuous moisture set-ups and large-scale window frame weathering

X-ray tomography as a tool for detailed anatomical analysis

Wood identification, anatomical examination and retrieval of quantitative information arc important aspects of many research disciplines. Conventional light microscopy with a camera and (semi)automatic image analysis software is an often used methodology for these purposes. Morc advanced techniques such as fluorescence, scanning electron, transmission electron, confocal laser scanning and atomic force microscopy arc also part of the toolset answering to the need for detailed imaging. Fast, non-destructive visualization in three dimensions with high resolution combined with a broad field of view is sought-after, especially in combination with flexible software. A highly advanced supplement to the existing techniques, namely X-ray sub-micron tomography, meets these requirements. It enables the researcher to visualize the material with a voxel size approaching <1 mu m for small samples (<1 mm). Furthermore, with tailor-made processing software quantitative data about the wood in two and three dimensions can be obtained. Examples of visualization and analysis of four wood species arc given in this paper, focusing on the opportunities of tomography at micron and sub-micron resolution. X-ray computed tomography offers many possibilities for material research in general and wood science in specific, as a qualitative as well as a quantitative technique

Hygrothermal behaviour of timber frame walls finished with a brick veneer cladding

In this study, two typical timber frame walls with brick veneer cladding have been constructed at KU Leuven to investigate the hygrothermal response of these constructions in a moderate sea climate. Main topic of research is the contradictory criterion for the wind barrier when it comes to the risk on interstitial condensation for winter and summer conditions: in winter a vapour open wind barrier is appropriate, in summer a more vapour tight. Therefore, similar walls but with different types of wind barrier have been investigated. In one set-up a vapour open bituminous impregnated wood fibre board is used as wind barrier, whereas in the second set-up a more vapour tight wood fibre cement board is used. The study shows that a high relative humidity can be expected at the interface between insulation and wind barrier during winter conditions, leading to a high mould growth index. In contrast, the relative humidity at the interface between insulation and inner vapour retarder during summer is lower than expected. This can be caused by the buffering capacity of the hygroscopic materials in the wall

From leaf to label : a robust automated workflow for stomata detection

Leaf stomata are microscopic pores on the leaves of plants which control the balance between water loss and CO2 uptake by the plant. As plants adapt their stomatal traits in response to environmental parameters such as water availability, temperature and atmospheric carbon dioxide concentrations, stomatal size and density of preserved leaves have allowed for reconstruction of past climates. Stomata serve as 'gates' between deep-soil water reservoirs and the atmosphere and are a key determinant of transpiration in models for operational predictions of the near-climate. It is well known that stomatal size and density vary widely across plant species and even though efforts have mapped stomatal behavior globally, more detail is needed as including more interspecific trait variation in climate models could significantly reduce the error in model predictions. Despite their important function, no standardized methodology has yet been described to measure stomatal traits which is widely considered to be labour-intensive and time-consuming and to this day mostly performed manually. Herbaria contain a treasure of unique ecological data covering large temporal scales. We used the African Herbarium of Meise Botanic Garden which contains over 1.2 million African specimens with a very good coverage of the Congo Basin (dating back to 1880) to develop a workflow for extracting stomatal trait data starting from the herbarium specimen, involving the automatic detection of stomata using a deep learning approach. The purpose of developing this workflow is to generate a large amount of data on stomatal traits on an easy, cost- and time- efficient manner. Here, we will present the leaf-to-label workflow and demonstrate how it was used to study the effect of global change on leaf adaptation in central African rainforest over the past 100 years

Preventive action of organosilicon treatments against disfigurement of wood under laboratory and outdoor conditions

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