Lone Ross
Head of Department/Head of Research
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Gry Alfredsen Lone Ross Michael Altgen Igor A. Yakovlev Anne-Cathrine Flyen Mari sand Austigaard Johan Mattsson Nanna Bjerregaard PedersenAbstract
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Gry Alfredsen Lone Ross Michael Altgen Igor A. Yakovlev Anne-Cathrine Flyen Mari sand Austigaard Johan Mattsson Nanna Bjerregaard PedersenAbstract
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Lone Ross Lizhen Huang Erik Trømborg Roja Modaresi Hanne Kathrine Sjølie Kristina Bringedal GeddeAbstract
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In the context of BioCities, the circular bioeconomy has transformative potential in rethinking urban areas, especially using urban, peri-urban, and rural forestry as a nature-based solution. These can be seen as an interconnected forest network providing essential and high-value services, such as health benefits and climate resilience, and sustainable products, principally through rural and peri-urban forests.
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Gry Alfredsen Lone Ross Michael Altgen Igor A. Yakovlev Anne-Cathrine Flyen Mari sand Austigaard Johan Mattsson Nanna Bjerregaard PedersenAbstract
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Gry Alfredsen Lone Ross Mari Sand Austigard Johan Mattsson Anne Cathrine Flyen Nanna BjerregaardAbstract
This report is a documentation of the field data collection and sampling at Svalbard in 2022 within the project ArcticAlpineDecay. The sampling methods are described and for each object sampling was performed documentation is provided, incl. location, Askeladden ID, map coordinate, photo documentation and illustration of sampling. Compilation of the results from the project will be published in peer review journals and in a final report from the project.
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Lone Ross Lizhen Huang Erik Trømborg Roja Modaresi Hanne Kathrine Sjølie Callum Aidan Stephen HillAbstract
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Gry Alfredsen Lone Ross Atle Wehn Hegnes Mari Sand Austigard Johan Mattsson Nanna Bjerregaard Anatoly Sinitsyn Vibeke Vandrup Martens Anne Cathrine FlyenAbstract
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The purpose of this research is to develop a method for estimating the spatially and temporally resolved moisture content of thermally modified Scots pine (Pinus sylvestris) using remote sensing. Hyperspectral time series imaging in the NIR wavelength region (953–2516 nm) was used to gather information about the absorbance of eight thermally modified pine samples each minute as they dried during a period of approximately 20 h. After preprocessing the collected spectral data and identifying an appropriate wavelength selection, partial least squares regression (PLS) was used to map the absorbance data of each pine sample to a distribution of moisture contents within the samples at different time steps during the drying process. To enable separate studying and comparison of the drying dynamics taking place within the early- and latewood regions of the pine samples, the collected images were spatially segmented to separate between early- and latewood pixels. The results of the study indicate that the 1966–2244 nm region of a NIR spectrum, when preprocessed with extended multiplicative scatter correction and first order derivation, can be used to model the average moisture content of thermally modified pine using PLS. The methods presented in this paper allows for estimation and visualization of the intrasample spatial distribution of moisture in thermally modified pine wood.
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Understanding the quality of new raw material sources will be of great importance to ensure the development of a circular bioeconomy. Building up quality understanding of wood waste is an important step in this development. In this paper we probe two main questions, one substantial and one theoretical: What different understandings of wood waste quality exist and what significance do they have for the recycling and re-use of this waste fraction? And, what is the evolution of knowledge and sustainable practices of wood waste qualities a case of? The analysis is based on diverse perspectives and forms of methods and empirical material. Studies of policy documents, regulations, standards, etc. have been reviewed to uncover what kind of measures and concepts that have been important for governing and regulating wood waste handling. Interviews concerning wood and wood waste qualities have been conducted with key informants and people visiting recycling and waste management stations in Oslo and Akershus in Norway. By studying quality conceptions through the social birth, production, life, end-of-life and re-birth of wood products, we analyse socio-cultural conditions for sustainability. Furthermore we show how the evolution of knowledge and sustainable practices of wood waste qualities, in the meeting with standards and regulations, is a case of adaptation work in the evolution of Norwegian bioeconomy.
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Gry Alfredsen Erik Larnøy Greeley Beck Johan Bjørnstad Lone Ross Callum Aidan Stephen Hill Andreas TreuAbstract
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Surface mould growth contributes to the colour changes of outdoor exposed wood over time. Modelling mould growth can thus help visualize wooden facades’ colour development, which can improve facade design and service life. However, existing wood mould models do not consider transient wetting effects that occur outdoors due to precipitation and condensation. To address this, four mould models were evaluated using laboratory experimental data that included exposure to transient wetting. First, the models (the original and the updated VTT model, the biohygrothermal model and the mould resistance design (MRD) model) were evaluated for Scots pine sapwood. For this evaluation, the transient wetting effect was implemented in the models by using hourly wood surface relative humidity (RH), calculated from electrical resistance measurements, as input. This showed that the original and the updated VTT model gave best fit to the experimental data. However, further evaluation of these two models for more wood materials showed that the updated VTT model was sensitive to the choice of material parameters. Large discrepancies occurred when varying the material parameters in the updated VTT model. Finally, different estimates of RH were tested in the original VTT model. Using wood surface RH as input gave best fit to the experimental data, and ambient air RH gave poorest fit. Overall, the results indicate that the original VTT model is fairly reliable and can be used to predict mould growth on wooden claddings exposed to transient wetting as long as the wood surface climate is used as climatic input data.
Authors
Andreas Treu Katrin Zimmer Christian Brischke Erik Larnøy Lone Ross Foued Aloui Simon M. Cragg Per-Otto Flæte Miha Humar Mats Westin Luisa Borges John WilliamsAbstract
Timber structures in marine applications are often exposed to severe degradation conditions caused by mechanical loads and wood-degrading organisms. This paper presents the use of timber in marine environments in Europe from a wood protection perspective. It discusses the use of wood in coastline protection and archeological marine wood, reviews the marine borer taxa in European waters, and gives an overview of potential solutions for protection of timber in marine environments. Information was compiled from the most relevant literature sources with an emphasis on new wood protection methods; the need for research and potential solutions are discussed. Traditionally, timber has been extensively utilized in a variety of marine applications. Although there is a strong need for developing new protection systems for timber in marine applications, the research in this field has been scarce for many years. New attempts to protect timber used in marine environments in Europe have mainly focused on wood modification and the use of mechanical barriers to prevent colonization of marine wood borers. The importance of understanding the mechanisms of settlement, migration, boring, and digestion of the degrading organisms is key for developing effective systems for protecting timber in marine environments.
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Carbon footprint over the life cycle is one of the most common environmental performance indicators. In recent years, several wood material producers have published environmental product declarations (EPDs) according to the EN 15804, which makes it possible to compare the carbon footprint of product alternatives. The objective of this study was to investigate the effect of service life aspects by comparing the carbon footprint of treated wood decking products with similar performance expectations. The results showed that the modified wood products had substantially larger carbon footprints during manufacturing than preservative-treated decking materials. Replacement of modified wood during service life creates a huge impact on life cycle carbon footprint, while maintenance with oil provided a large contribution for preservative-treated decking. Hence, service life and maintenance intervals are crucial for the performance ranking between products. The methodological issues to be aware of are: how the functional unit specifies the key performance requirements for the installed product, and whether full replacement is the best modeling option in cases where the decking installation is close to the end of the required service life.
Authors
Lone RossAbstract
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Laboratory screening tests are commonly used to indicate wood materials’ resistance or susceptibility to surface mould growth, but the results can deviate from what happens during outdoor exposure. In this study, the aim was to investigate how well agar plate screening tests and water uptake tests can predict mould growth on exterior wooden claddings. The tested wood materials included Norway spruce heartwood (Picea abies), sapwood and heartwood of Scots pine (Pinus sylvestris), aspen (Populus tremula), acetylated Radiata pine (Pinus radiata) and DMDHEU-modifed Scots pine sapwood. The agar plate test included four inoculation methods (two monoculture spore suspensions of Aureobasidium species, one mixed-culture spore suspension, and inoculation from outdoor air) and three incubation temperatures (5, 16 and 27 °C). Inoculation method and incubation temperature had signifcant efects on the mould rating in the agar plate screening test, but none of the agar plate test combinations gave good indications of outdoor performance. Results from the agar plate test gave signifcantly negative correlations or no signifcant correlation with results from the outdoor test. However, the water uptake test gave signifcantly positive correlations with outdoor mould rating, and could be a useful indicator of susceptibility of uncoated wooden claddings to surface mould growth.
Abstract
Understanding the quality of new raw material sources will be of great importance to ensure the development of a circular bioeconomy. Building up quality understanding of wood waste is an important step in this development. In this paper we probe two main questions, one substantial and one theoretical: What different understandings of wood waste quality exist and what significance do they have for the recycling and re-use of this waste fraction? And, what is the evolution of knowledge and sustainable practices of wood waste qualities a case of? The analysis is based on diverse perspectives and forms of methods and empirical material. Studies of policy documents, regulations, standards, etc. have been reviewed to uncover what kind of measures and concepts that have been important for governing and regulating wood waste handling. Interviews concerning wood and wood waste qualities have been conducted with key informants and people visiting recycling and waste management stations in Oslo and Akershus in Norway. By studying quality conceptions through the social birth, production, life, end-of-life and re-birth of wood products, we analyse socio-cultural conditions for sustainability. Furthermore we show how the evolution of knowledge and sustainable practices of wood waste qualities, in the meeting with standards and regulations, is a case of adaptation work in the evolution of Norwegian bioeconomy.
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This study addresses changes in visual appearance of unpainted wood materials exposed outdoors. Specimens of aspen (Populus tremula), Norway spruce (Picea abies), untreated Scots pine (Pinus sylvestris), DMDHEU-modified Scots pine and acetylated Radiata pine (Pinus radiata) were exposed facing south in Ås, Norway for 62 weeks. During this period, mould growth coverage, lightness (L*) and the uniformity of the weather grey colour were assessed. Mould growth coverage was evaluated visually using a rating system. L* and the uniformity were evaluated using image analysis. The increase in mould rating of the wood materials developed in varying speed, but all specimens had reached the maximum rating after 42 weeks. Until then, the changes in L* correlated significantly with the mould rating. However, the specimens continued to darken after they had reached maximum mould rating. DMDHEU was the only material that obtained a more uniform colour as a consequence of the weathering.
Authors
Lone RossAbstract
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It is recognised that flame retardant chemicals degrade and leach out of flame-protected wood claddings when exposed to natural weathering. However, the ability to survey the current state of a flame retardant treatment applied to a wood cladding, an arbitrary length of time after the initial application, is limited today. In this study, hyperspectral imaging in the near infrared to short-wavelength infrared region is used to quantify the amount of flame retardant present on wooden surfaces. Several sets of samples were treated with various concentrations of a flame retardant chemical and scanned with a push broom hyperspectral camera. An inductively coupled plasma (ICP) spectroscopy analysis of the outermost layer of the treated samples was then carried out in order to determine each sample’s phosphorus content, the active ingredient in the flame retardant. Spectra from the hyperspectral images were pre-processed with extended multiplicative scatter correction, and the phosphorus content was modelled using a partial least squares (PLS) regression model. The PLS regression yielded robust predictions of surface phosphorus content with a coefficient of determination, R2, between 0.8 and 0.9 on validation data regardless of whether the flame retardant chemical had been applied to the surface of the wood or pressure-impregnated into it. The result from the study indicates that spectral imaging around the 2400–2531nm wavelength region is favourable for quantifying the amount of phosphorus-based flame retardant contained in the outermost layer of non-coated wooden claddings. The results also reveal that the uptake of phosphorus-based flame retardant does not occur uniformly throughout the wood surface, but is to a larger extent concentrated in the earlywood regions than in the latewood.
Authors
Andreas Treu Katrin Zimmer Christian Brischke Erik Larnøy Lone Ross Foued Aloui Simon M Cragg Per Otto Flæte Miha Humar Mats Westin Luisa M. S. Borges John WilliamsAbstract
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The aim of this research is to determine if the polyesterification of sorbitol and citric acid in wood has a future potential as a wood modification process. Pine wood was impregnated with an aqueous solution containing citric acid and sorbitol and was thereafter cured at 103 or 140°C for 18 hours. The dimensional stability and leaching resistance were studied for both modification temperatures. The leachates from the modified wood samples were analysed by HPLC and the susceptibility to decay and staining fungi were studied. Impregnated samples cured at 140°C showed a permanent (leach-resistant) increased dimensional change, but samples treated at 103°C were not stable to leaching. Treated samples cured at 103 and 140°C showed significant resistance to white-rot (Trametes versicolor) and brown-rot decay (Postia placenta) after a leaching procedure. Furthermore, samples cured at 103 and 140°C (leached and unleached) were significantly less susceptible to blue-stain fungi than the untreated controls.
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Effects of climatic factors and material properties on the development of surface mould growth on wooden claddings were investigated in a laboratory experiment. Specimens of aspen (Populus tremula), Siberian larch (Larix Sibirica), American white oak (Querqus alba), Scots pine (Pinus sylvestris), Norway spruce (Picea abies) and thermally modified pine were incubated in eight climatic chambers at specified wetting periods (2 or 4 h per day), relative humidity (58–86%) and temperature conditions (10–27°C). Surface mould growth was assessed weekly for 13 weeks, and the results were evaluated statistically using Generalized Estimating Equations logistic regression models. All tested climatic factors had significant effects on the mould growth, and there were significant differences between the materials. The ranking of the materials varied with temperature and over time. Aspen, pine sapwood and oak were overall most susceptible to mould growth, and thermally modified pine least susceptible. There were significant differences between sapwood and heartwood for pine and spruce. The effect of density was tested on the spruce heartwood material, but was not found to be significant. The results can be used to further develop prediction models for mould growth on wooden claddings.
Abstract
This study addresses changes in visual appearance of unpainted wood materials exposed outdoors. Specimens of Norway spruce (Picea abies) Scots pine (Pinus sylvestris), aspen (Populus tremula), acetylated Radiata pine (Pinus radiata) and DMDHEU-modified Scots pine sapwood were exposed facing south in Ås, Norway for 60 weeks. During this period, surface mould growth development and wasp attack were assessed visually. Development in lightness (L*) and the uniformity of the weather grey colour were assessed by image analysis. The mould rating of the tested wood materials developed in varying speed, but all specimens had reached the maximum rating after 42 weeks. Our results indicate that most specimens continued to darken after the specimens had reached maximum mould rating, and that evaluation of L* can provide additional information about the surface mould growth. Furthermore, our results indicate that most materials developed a less uniform appearance than what was initially, except from DMDHEU which obtained a more uniform appearance as a consequence of the weathering. This study also shows that wasp attack can give a lighter appearance of the wood by chewing off the top weathered layer. Different wood substrates were attacked in varying degree. Aspen was the substrate most severely attacked by wasps while the acetylated wood was not attacked at all during the 60 weeks of exposure.
Authors
Anna Sandak Jakub Sandak Athanasios Dimitriou Ingunn Burud Thomas Kringlebotn Thiis Lone Ross Graham Alan Ormondroyd Dimitrios KraniotisAbstract
Bio-based building materials offer a wide range of outlooks, from traditional rustic to modern design products. Recent development in the science of materials significantly improves their functional performance. However, when considering the use of bio-materials in outdoor environments, materials will deteriorate due to processes like weathering, oxidation, biodegradation, wear, and decay. Consequentially, biomaterials may lose visual appeal, leading to a perceived need for replacement even if the material is far from reaching functional failure. Visual assessment is the most direct method for evaluation of the aesthetic appearance of materials. However, it possesses a high degree of subjectivity when performed by an untrained person. On the contrary, measurement of surface properties with dedicated sensors provides objective values that might be related to the current state of the material in use. Recent developments in field of optics and electronics opens a new possibility to perform measurements in-situ. Colour-, gloss-, or spectro-photo-meters allow non-destructive measurements without particular sample preparation. Since all of the above techniques provide complementary information, the multi-sensor approach is more frequently suggested for applied research. The material state can be assessed regularly during service life. In this case, such measurement turns into monitoring. The paper illustrates examples of assessment and monitoring of biomaterials’ degradation due to weathering. Direct implementation of various sensors is demonstrated. A proposal for the approach of combining data provided by various sensing techniques with data mining is also presented.
Authors
Graham Alan Ormondroyd Gry Alfredsen Raghavalu Thirumalai Durai Prabhakaran Simon F. Curling Bronia K. Stefanowski Morwenna J. Spear Lone RossAbstract
Microbiological degradation of wood by decay fungi can cause a rapid change in the structural properties of timber which can result in both strength and mass loss. Traditional techniques for the evaluation of decay (e.g. mass loss) lack the sensitivity to evaluate the effects of the very first stages of the decay process. This paper describes the effects of initial brown rot decay, defined by the amount of Poria placenta genomic DNA (gDNA) present in the samples, on the dynamic mechanical properties of the timber. It was found that there is a correlation between the mean storage modulus of the timber and the amount of P. placenta gDNA present, and therefore the level of decay. This shows that using dynamic mechanical analysis is a viable technique that can be used to study initial decay processes.
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Mould growth is an important contributor to colour change of untreated wood exposed outdoors. Predicting the development of mould growth is therefore important to ensure successful use of untreated wood as a façade material. More knowledge about the factors affecting mould growth on outdoor exposed wood is required to give better predictions. In this study, climatic factors and material properties affecting mould growth have been investigated by exposing selected wooden specimens (aspen, pine sapwood, pine heartwood, spruce sapwood and spruce heartwood) to 8 different climates for 91 days. The climates were defined in a factorial design with two levels of relative humidity (65 and 85 %), wetting period (2 and 4 hours per day) and temperature (10 and 25 °C), respectively. The degree of mould growth was visually evaluated once a week during the exposure period. Aspen and pine sapwood were the substrates most susceptible to mould growth. There were no significant differences in susceptibility between pine heartwood and spruce heartwood, but the difference between heartwood and sapwood was significant for both pine and spruce. The effect of density on mould growth was tested for the spruce heartwood material, but was not found to reduce the residual variance significantly. However, all the tested climatic factors affected mould growth significantly; relative humidity was most important, while there was a somewhat smaller effect of wetting period and a minor effect of temperature. Overall, increased RH, longer wetting period and increased temperature had a positive effect on the mould growth. It was found a significant interaction between temperature and relative humidity, indicating that the temperature had larger effect on the mould growth at lower relative humidity, and that the relative humidity had larger effect at lower temperature. There was a tendency that the relative performance of the substrates was dependent on climate, but this interaction effect was not significant for any of the climatic factors.
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Lone RossAbstract
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Lone RossAbstract
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Authors
Anna Komasa Anna Klementyna Przybył Piotr Barczynski Izabela Ratajczak Kinga Szentner Magdalena Wozniak Pawel Kowalewski Waldemar Perdoch Grzegorz Cofta Patrycja Kwaśniewska-Sip Joanna Siuda Wojciech Grzeskowiak Krystofiak Tomasz Lone Ross Janka Dibdiakova Magdalena Broda Bartłomiej MazelaAbstract
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Due to more restrictive toxicological requirements and increased ecological awareness of consumers, wood preservatives containing harmful biocides are no longer desired on the market. Therefore, research on new environmentally friendly formulations is of great importance. One of the possible solutions is to develop new preservatives based on natural substances, which are harmless to humans, animals and the environment, while biologically active. The aim of the study was to develop new biocide-free preservative systems which increase wood resistance to wood-decaying fungi. The following silanes: [3-(2-Aminoethylamino)propyl]trimethoxysilane (AATMOS), (Aminopropyl)triethoxysilane (APTEOS), and (Aminopropyl)trimethoxysilane (APTMOS); caffeine, natural oils and potassium carbonate were chosen as components of new protective formulations, which were planned to be an alternative for traditionally used biocides. Samples of three different wood species (pine, spruce, and poplar) were treated with the new preservative systems and exposed to the brown-rot fungus Coniophora puteana and the white-rot fungus Coriolus versicolor according to EN-113 and EN-839 standards. The obtained results show that wood treated with the water-based formulation consisting of silanes and caffeine (2% caffeine + 5% AATMOS, 2% caffeine + 5% APTEOS) demonstrated the highest resistance to the test fungi. Wood mass loss after exposure to the decay fungi was 1%. All wood species treated with this formulation achieved index 1 (“very resistant”) within durability class acc. to the EN350 standard.
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Understanding the influence of weathering factors and the material degradation mechanisms are fundamental for modelling the weathering process of wood. The goal of this work was to investigate the combined effect of time and exposure on the physical-chemical mechanisms of wood weathering. Four exposure directions (North, South, East and West) were investigated. Experimental tests were performed for 28 days through July, which according to previous research is considered as the most severe period for weathering of wood micro-sections. Measurements of samples included: photogrammetry, near and mid infrared spectroscopy, colour measurement, SEM observation and visual assessment. Parameters obtained by measuring the weathered surfaces with various sensors were compared with the subjective visual assessment by an expert evaluator. Algorithm based on multi sensor data fusion allowing calculation of the “weathering indicator” was developed. It was concluded that the progress of degradation is clearly correlated to the solar radiation and the exposure direction seems to have a clear effect on the degradation intensity.
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Growth of dark moulds enables the use of a decorative and protective biofinish for wood, showing advantages compared to traditional wood-coatings in terms of sustainability and selfrepair. Based on the formation of a uniform mould covering on oil treated wood during outdoor exposure, the utilisation of a biofinish is in development. Basic information is lacking on the correlation between exposure site and biofinish formation on wood. To evaluate the impact of different locations, a biofinish assessment method was applied on different combinations of wood species and vegetable oil types after outdoor exposure in the Netherlands and Norway. Biofinishes were detected on wood samples made of spruce, pine sapwood and ilomba that were treated with olive oil and on pine sapwood treated with raw linseed oil after one and a half year of outdoor exposure in the Netherlands. More time was needed for biofinish formation on multiple wood-oil combinations for samples exposed in Norway. After two years of outdoor exposure three out of five wood-oil combinations that contained biofinishes in the Netherlands, showed similar results with the samples in Norway. Biofinish formation was not detected at all on untreated wood samples, regardless the wood species or exposure site. Loose fibres were observed on the surface of all untreated samples. It is likely that biofinish formation was prevented by the removal of stained fibres. Analysis of the stain coverage development on the wood samples, including initial stages of biofinish formation, showed a significant effect of exposure time and (oil) treatment on the stain coverage.
Authors
Lone RossAbstract
No abstract has been registered
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In order to determine the relation between the structural properties and fungistatic activity of quinolizidine and bisquinolizidine alkaloids, the bioactive derivatives of cytisine, sparteine and lupanine were tested for the inhibitory activity against the microfungus causing mould growth phenomenon (Aspergillus niger van Tieghem ATCC 6275). The compounds tested were screened for antifungal properties using the bioautography-TLC. According to the results, the following cytisines showed an inhibiting effect on mould; spirocytisine, 3,5-dibromocytisine, bromo-N-boccytisine, N-Boccytisine, 3-bromobenzylocytisine, 4-bromo-benzylcytisine, 3-iodobenzylcytisine, 4-iodobenzylcytisine.
Authors
Anna Sandak Ingunn Burud Andreas Svarstad Flø Thomas Kringlebotn Thiis Lone Ross Jakub SandakAbstract
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Lone RossAbstract
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Lone RossAbstract
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Authors
Knut Arne Smeland Kristian Hovde Liland Jakub Sandak Anna Sandak Lone Ross Thomas Kringlebotn Thiis Ingunn BurudAbstract
Untreated wooden surfaces degrade when exposed to natural weathering. In this study thin wood samples were studied for weather degradation effects utilising a hyperspectral camera in the near infrared wavelength range in transmission mode. Several sets of samples were exposed outdoors for time intervals from 0 days to 21 days, and one set of samples was exposed to ultraviolet (UV) radiation in a laboratory chamber. Spectra of earlywood and latewood were extracted from the hyperspectral image cubes using a principal component analysis-based masking algorithm. The degradation was modelled as a function of UV solar radiation with four regression techniques, partial least squares, principal component regression, Ridge regression and Tikhonov regression. It was found that all the techniques yielded robust prediction models on this dataset. The result from the study is a first step towards a weather dose model determined by temperature and moisture content on the wooden surface in addition to the solar radiation.
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There is an increasing awareness of how the aesthetical performance of wood exposed outdoors changes over time and especially in the first few years after installation. Mould and blue stain fungi are biological agents that contribute to the weather grey colour on a wooden façade, and the blue stain fungi Aureobasidium pullulans is commonly identified as colonizer on coated and uncoated wood exposed outdoors. In this study 21 wood substrates (untreated, preservative treated and modified) were tested for their susceptibility to A. pullulans when incubated at three different temperatures (11, 16 and 22°C). Western red cedar and preservative treated wood had the lowest mould ratings at the end of the test period (84 days). Alder, ash, Norway spruce and Sitka spruce reached maximum rating already at day 28, and at day 84 also aspen, European larch, thermally modified pine, birch, acetylated pine and DMDHEU modified pine had reached maximum rating. Incubation temperature had a significant influence on the growth of A. pullulans throughout the test period for acetylated and DMDHEU modified samples – and generally the modified wood substrates were more sensitive to changes in temperature than the other tested substrates. Scots pine sapwood seemed to be less susceptible to A. pullulans in mono cultures, demonstrating low mould ratings throughout the test period. This contradicts to previous studies were Scots pine sapwood tended to have high susceptibility when using a mix of mould and blue stain fungi.
Authors
Lone Ross Thomas Kringlebotn Thiis Geir Isak Vestøl Ingunn Burud Solrun Karlsen Lie Olav Albert HøibøAbstract
Use of uncoated wood in building façades has increased the last years, and therefore it is important to understand and control the aesthetical character and appearance of wood materials used outdoors. By predicting the aesthetical service life and the visual appearance of a wooden façade over time, we can accommodate some of the end-user expectations, perception, values and aesthetical preferences. The spatial variation of climate on a façade is large, and estimation of the weathering process and mould growth on outdoor exposed wood should be based on the actual surface climate rather than data from meteorological stations. A first version of a simulation model that aims to predict and visualize future aesthetical appearance of wooden façades has been developed. The model is based on existing mould growth models and on a new model for surface meteorological conditions that account for RH, temperature and UV. The on-set of mould growth on selected wood materials (pine, spruce, larch, oak, aspen, thermally treated pine) have been studied in 8 different controlled climate conditions, where two levels of surface condensation regimes have been mimicked to capture time-of-wetness. Wood samples in conditions with high RH (85%) and longest time-of-wetness had the earliest on-set of mould growth, and under these conditions temperature (25°C/10°C) had no significant impact. Generally aspen had the earliest on-set of mould growth and thermally treated pine the latest. Data on on-set of mould growth will be incorporated in the simulation model to enable a knowledge-based decision tool regarding design and material selection.
Abstract
Uncoated wood is increasingly used in building façades in Northern Europe. The benefits can be both low maintenance and low environmental impact. An even, grey color of the façade is often the intention, but in several cases, an uneven pattern of light, grey and dark/black areas is the result. The effect of weathering and the influencing factors have to be considered when designing and building uncoated and coated wooden façade to avoid unwanted weathering effects. Wood weathering is commonly described to be caused by: accumulation of extractives on the surface, photo-degradation of lignin, staining by dark colored mould fungi, checking, cracking and splitting due to moisture fluctuation and erosion. This paper reviews, analyzes and exemplifies weathering as a finishing system and design option for uncoated wood. Furthermore, it also discusses and exemplifies the main influencing factors and weathering effects on coated wood in facades.
Abstract
Wooden elements may be subjected to mechanical, environmental or biological alterations during their service life. The most susceptible parts of wood structural members are the exposed surfaces since they are subjected to ageing, weathering and/or decay. Knowledge of the influence of weathering factors and polymer degradation mechanisms is essential for understanding the weathering process of wood. The goal of this study was to investigate the degradation of thin wooden samples exposed to short-term weathering. Tests were performed through the European summer (July), which according to previous research is considered as the most severe period for weathering of wood micro-sections. Fourier transform near infrared spectroscopy was used for evaluation of chemical changes of wood samples. Three approaches for data evaluation are presented in this paper: (1) direct spectral interpretation, (2) a concept for calculation of a weathering index Wind and (3) kinetics of lignin changes in relation to the exposure direction for selected wavelengths. Observation of the effects of weathering will allow better understanding of the degradation process. The southern exposure site was slightly more affected by weathering than other sites. Results of this research will be used for future determination of the weather-dose response model and could be essential for predicting the future performance of timber facade elements.
Authors
Elke J. van Nieuwenhuijzen Michael F. Sailer Lone Ross Olaf C. G. Adan Peter J. Punt Robert A. SamsonAbstract
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Lone RossAbstract
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Mold growth on the surface of wooden façades is usuall y dealt with by using surface treatment such as paint with fungicides. However, new developments in architecture ar e m oving towards less use of coating, and more use of untreated wooden clad dings. Mould growth is well understood and described, and several m odels for predicting mould growth on building materials exist. It is commonly k nown that mould growth is directly controlled by the cli mate which the w ood is exposed to. Several authors identify humidity, temperature and time as the main drivers of mould growth. However, most of the cu rrent g rowth models developed are based on lab oratory measurements at stable climatic conditions. Consequently, these models are less suitable for prediction of mould growth on exterior surfaces exposed to rapidly changing weather conditions . T his paper analyses the effect of variations of meteorological data on the mould growth on wooden clad dings. An experimental setup of wood samples was exposed to outdoor conditions and h ourly weather conditions as well as t he mould growth at different intervals were measured. The measurements were supplied with 1- D Heat And Moisture (HAM) simulations to provide a more accurate estimate of the conditions on the surface of th e sa mples. The purpose of the analysis was to evaluate if an existing mould growth model might be applicable also for predicting outdoor mould growth. Several profiles of temperature and moisture were co ntinuously monitored on different locations of an eight - story building made from Cross Laminated Timber (CLT). The results from the an alysis of the samples of wood cladding were used to model the mould growth on different l ocations of the building. Also the drying effect of wind around the building was studied. The study shows that there is large variatio n of potential mould growth on the façade of the building.
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Lone RossAbstract
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A wide range of forest products and industries have been examined in life cycle analyses (LCA). Life cycle data are essential for identifying forestry operations that contribute most to carbon emissions. Forestry can affect net CO2 emissions by changing carbon stocks in biomass, soil and products, by supplying biofuels to replace fossil fuels as well as by establishing new forests. The transport of forest products is crucial to greenhouse gas (GHG) emissions. We conceptualize the chain from seed production, silviculture, harvesting, and timber transport to the industry as a system. Inputs to the system are energy and fuel, the output represents GHG emissions. The reference functional unit used for the inventory analysis and impact assessment is one cubic meter of harvested timber under bark. GHG emissions from forestry in East Norway were calculated for the production of one such unit delivered to the industry gate in 2010 (cradle-to-gate inventory), showing that timber transport from the forest to the final consumer contributed with more than 50 % to the total GHG emissions. To assess uncertainty of model approaches, the LCA was conducted with two different models, SimaPro and GaBi, both using the Ecoinvent database with data adapted to European conditions.
Abstract
A wide range of forest products and industries have been examined in life cycle analyses (LCA). Life cycle data are essential for identifying forestry operations that contribute most to carbon emissions. Forestry can affect net CO2 emissions by changing carbon stocks in biomass, soil and products, by supplying biofuels to replace fossil fuels as well as by establishing new forests. The transport of forest products is crucial to greenhouse gas (GHG) emissions. We conceptualize the chain from seed production, silviculture, harvesting, and timber transport to the industry as a system. Inputs to the system are energy and fuel, the output represents GHG emissions. The reference functional unit used for the inventory analysis and impact assessment is one cubic meter of harvested timber under bark. GHG emissions from forestry in East Norway were calculated for the production of one such unit delivered to the industry gate in 2010 (cradle-to-gate inventory), showing that timber transport from the forest to the final consumer contributed with more than 50 % to the total GHG emissions. To assess uncertainty of model approaches, the LCA was conducted with two different models, SimaPro and GaBi, both using the Ecoinvent database with data adapted to European conditions.
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Authors
Lone RossAbstract
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Lone RossAbstract
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Ingunn Burud Lone Ross Andreas Svarstad Flø Knut Kvaal Sigrun Kolstad Thomas Kringlebotn ThiisAbstract
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The study describes the development of surface mould and blue stain fungi on painted wooden claddings exposed to outdoor weathering. The materials consisted of Norway spruce (Picea abies) claddings that were processed from inner boards, outer boards, and edge-grained boards with known origin. Heartwood proportion, density, annual ring width, knot diameters and relative knot area were measured, and all boards were coated with the same water-borne alkyd modified acrylic paint system. Most of the tangentially sawn boards were coated on the side facing the pith, but a sub-sample was coated on the opposite side for comparison. The specimens were exposed with a 45° angle of inclination facing south in a field trial in Oslo from 2007 to 2011, and mould growth was evaluated visually according to EN 927-3. The development of mould rating was described with an ordinal logistic regression model. The model predicts expected mould rating to follow a sigmoid curve with some deviation in the first part. Neither wood properties nor manufacturing characteristics had any significant effect on the model, and this may in part be due to the use of a high performance coating system.
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Development of surface moulds and staining fungi on painted spruce panels with known origin and wood properties was investigated over a period of 4 years. Materials of Norway spruce (Picea abies) were sampled from two sites with high-productive forest on lowland in South-eastern Norway and two low-productive sites at higher altitudes and somewhat farther north. Claddings were processed from inner centreboards (mainly heartwood) and outer centerboards of both butt logs and second logs. A sub-sample of radially sawn claddings was compared with corresponding tangentially sawn claddings. Heartwood proportion, density, annual ring width, knot diameters and knot area were measured. All panels were coated with the same water-borne alkyd modified acrylic paint system. Most of the tangentially sawn claddings were coated on the side facing pith, but a sub-sample was coated on the opposite side for comparison. The specimens were exposed with 45˚ angle of inclination facing south in a field trial in Oslo from 2007 to 2011, and mould growth was evaluated visually according to EN 927-3. 7.7% of the specimens were rated as 2, 71.4% were rated as 3, 19.4% were rated as 4, and 1.5% were rated as 5. Outer boards were rated significantly higher than inner boards, while differences between origins were not significant. There was a tendency of decreased rating with increasing heartwood proportion, but the relationship was not significant. Nor was there any significant effect of annual ring with, density or knot properties. Neither the difference between radially and tangentially sawn claddings, nor the difference between specimens coated on the side facing pith was significant.
Abstract
Wood used in outside applications is susceptible to weathering and photo degradation, which often leads to surface discoloration, loss of brightness and surface deterioration. Research has shown that acetylated wood is more resistant against brown rot, white rot and soft rot, and more dimensionally stable than untreated wood. However, acetylated wood seems still to be disfigured by surface moulds and staining fungi. Samples of acetylated Southern Yellow pine at three different treatment levels; low, intermediate and high acetyl content were exposed at two test sites, Ås (Norway) and Bogesund (Sweden) against north and south from September 2010 until March/May 2011. Considerably more precipitation was recorded in Ås in the initial potential fungal growth phase than in Bogesund. As expected, untreated wood had higher mould ratings than acetylated wood. At Ås the tendency was that samples with low acetyl content had lower mould ratings than samples with higher acetyl content. This effect was not found in Bogesund. This may be due to considerably less precipitation in Bogesund compared to Ås. At Ås samples exposed against north tended to have higher mould ratings than panels exposed against south which could be due by less direct sun causing longer time of wetness and more ideal conditions for mould growth.
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Development in surface mould growth on painted/unpainted wooden claddings and acting climatic factors were investigated over a period of 3 years. Eight wood substrates, including modified, preservative-treated and untreated wood, were tested in combination with three types of paint: (1) water-borne alkyd modified acrylic paint without fungicide; (2) solvent-borne alkyd paint without fungicide; and (3) ICP (internal comparison product). One set of samples was exposed unpainted. The samples were tested according to a modified version of EN 927-3. A logistic regression model was fitted to the data. The degree of mould growth varied with exposure time, coating typology, wood substrate, temperature and relative humidity. Exposure time and coating typology contributed most to the model. After 3 years of outdoor exposure unpainted panels and panels coated with solvent-borne paint without fungicide had more mould growth than panels coated with ICP and water-borne paint without fungicide. Unpainted oil/copper–organic preservative-treated claddings had higher resistance to mould growth than other unpainted wood substrates. Coated untreated pine and coated acetylated pine were more susceptible to mould growth than other coated wooden substrates.
Abstract
Microbial disfigurement of coated wooden surfaces is considered a major maintenance concern and will shorten the aesthetic service life of wooden facades. The effect of the physical surface structure of a paint film when applied on wood may have an impact on the susceptibility to mould growth. Six model paints were formulated to give the following physical surface structures: glossy, matt, soft, hard, hydrophobic, and a film with air inclusion. The model paints and a standard paint, with and without fungicide, were applied on panels of Norway spruce (Picea abies L Karst.) and exposed outdoors for nearly three years according to a modified version of EN 927-3. A logistic regression model was fit to the data, and the degree of mould growth varied with exposure time and type of paint. Hard model paint was significantly more susceptible than the other model paints and had a performance close to the standard paint without fungicide. Soft model paint provided the best performance, with the least mould growth. Temperature, relative humidity, and precipitation did not significantly contribute to the model. (C) 2010 Elsevier Ltd. All rights reserved.
Abstract
Wood is a unique building material, but is by nature designed to deteriorate. A detailed understanding of the factors and interactions involved are important when working with service life prediction of wooden components in buildings. Wood may experience exponential fungal degradation caused by variation in the climatic factors within a small limited area and by minor imperfection in the wooden component. In this paper we put forward a new term: critical in-situ conditions (CIC). This is meant to bring the attention to the importance of looking into details in the construction design, the specific climatic factors and interactions involved. Gaining realistic and useful data for prediction of service life is only possible by controlling and understanding the factors that are target specific for a wooden component or even only a part of it. Performing measurements in a right way and in the proper part of the wooden component are vital for getting useful data for further processing. The objective in this paper is to exemplify the CIC in inservice situations and to describe the factors and interactions that control the service life. Case studies were performed on a building at Bryggen in Bergen, on a hunting cabin on Svalbard, on several wooden windows in the southern part of Norway and on an external wall of a residence house in Ås.
Division of Forest and Forest Resources
Deterioration and decay of wooden cultural heritage in Arctic and Alpine environments (ArcticAlpineDecay)
Division of Forest and Forest Resources
Circular use of wood for increased sustainability and innovation (circWOOD)
circWOOD will investigate aspects of wood use in the Norwegian economy, with particular emphasis on the reuse of wood in construction projects, and recycled wood as raw material in today's wood industry.