| 1. |
- Ahmed, Sheikh Ali, et al.
(författare)
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Mould susceptibility of Scots pine (Pinus sylvestris L.) sapwood : Impact of drying, thermal modification, and copper-based preservative
- 2013
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier. - 0964-8305 .- 1879-0208. ; 85, s. 284-288
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Tidskriftsartikel (refereegranskat)abstract
- The development of mould on wood surfaces depends on several factors. Although mould does not affect the mechanical properties of wood, it greatly reduces the aesthetic value of wood such as the sapwood of Scots pine (Pinus sylvestris L.), which is very prone to mould. In addition, adverse health effects of mould on humans are a great concern. Different types of dried and treated wood were used to observe whether they had enhanced durability against mould following an accelerated laboratory test method in a climate chamber. Samples were green, air-dried, industrially thermally modified, treated with copper-based preservative, and kiln-dried wood, which were tested within a single test run. The test produced the following main results: The thermal modification increased the durability of the wood, and the protective effectiveness of alternative treatments was comparable to that of commercially available copper-based treatment. However, the initial moisture content of the samples during mould exposure had a great influence on the onset of mould growth. The risk of mould susceptibility of industrial kiln-dried lumber can be reduced by drying using the double-layering technique and planing off the nutrient enriched evaporation surfaces.
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| 2. |
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| 3. |
- Ali, Alexandre Charifo, et al.
(författare)
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Comparative natural durability of five wood species from Mozambique
- 2011
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Ingår i: International Biodeterioration and Biodegradation. - : Elsevier BV. - 0964-8305. ; 65, s. 768-776
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to evaluate the natural durability of five lesser-utilized wood species from Mozambique. Both laboratory methods and field tests were applied for assessing wood decay of muanga (Pericopsis angolensis), metil (Sterculia appendiculata), namuno (Acacia nigrescens), ncurri (lcuria dunensis), and ntholo (Pseudolachnostylis maprounaefolia). Laboratory tests involved soft-, brown-, and white-rot fungi and termites. Heart- and sapwood of ncurri and ntholo were exposed in above-ground field tests; additionally, all species were exposed to in-ground contact tests. The results indicated that namuno, muanga, ncurri, and ntholo are resistant to soft-, brown- and white-rot fungi and the termite species Reticulitermes grassea and Mastotermes darwiniensis. Comparatively, soft-rot caused more severe decay on the studied wood species than did basidiomycete fungi. The brown-rot fungi Coniophora puteana, Gloeophiyllum trabeum, and Postia placenta caused less decay on the tested species than did the white-rot Trametes versicolor. Metil was not resistant to any of the mentioned hazards. Therefore, this species is not recommendable for exterior use if untreated. (C) 2011 Elsevier Ltd. All rights reserved.
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| 4. |
- Aslanzadeh, S., et al.
(författare)
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A comparative study between single- and two-stage anaerobic digestion processes : Effects of organic loading rate and hydraulic retention time
- 2014
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier. - 0964-8305 .- 1879-0208. ; 95, s. 181-188
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Tidskriftsartikel (refereegranskat)abstract
- The effect of an organic loading rate (OLR) and a hydraulic retention time (HRT) was evaluated by comparing the single-stage and two-stage anaerobic digestion processes. Wastes from the food processing industry (FPW) and the organic fraction of the municipal solid waste (OFMSW) were used as substrates. The OLR was increased at each step from 2 gVS/l/d to 14 gVS/l/d, and the HRT was decreased from 10 days to 3 days. The highest theoretical methane yield achieved in the single-stage process was about 84% for the FPW during an OLR of 3 gVS/l/d at a HRT of 7 days and 67% for the OFMSW at an OLR of 2 gVS/l/d and a HRT of 10 days. The single-stage process could not handle a further increase in the OLR and a decrease in the HRT; thus, the process was stopped. A more stable operation was observed at higher OLRs and lower HRTs in the two-stage system. The OLR could be increased to 8 gVS/l/d for the FPW and to 12 gVS/l/d for the OFMSW, operating at a HRT of 3 days. The results show a conclusion of 26% and 65% less reactor volume for the two-stage process compared to the single-stage process for the FPW and the OFMSW, respectively.
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| 5. |
- Atarijabarzadeh, Sevil, et al.
(författare)
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Inhibition of biofilm formation on silicone rubber samples using various antimicrobial agents
- 2011
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305 .- 1879-0208. ; 65:8, s. 1111-1118
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature-cured silicone rubber samples (silicone rubber (SIR) based on polydimethylsiloxane (PDMS)) and SIR samples containing three different antimicrobial agents, sodium benzoate (NaB), DCOIT (4,5 Dichloro-2-octyl-2H-isothiazolone-one) and p-aminobenzoic acid (PABA) were inoculated with fungal spore suspensions and incubated for 28 days at 29 +/- 1 degrees C and >= 90% humidity, according to the ISO 846:1997(E) protocol. Prior to the biodegradation test, a powder test was conducted to study the efficacy of the chosen antimicrobial compounds and to determine the correct concentration of the compounds for sample preparation. The extent of the microbial growth was studied visually and by Scanning Electron Microscopy (SEM). Changes in surface hydrophobicity and surface chemical composition were studied by contact angle measurements and Fourier Transform Infrared (FTIR) spectroscopy, respectively. Microbial growth and biofilm formation were observed on the surface of reference samples. DCOIT was the most effective antimicrobial agent, as demonstrated by the lack of microbial growth and unaltered surface hydrophobicity. On the surface of samples containing NaB, an initiation of microbial growth and therefore a slight change in surface hydrophobicity was observed. PABA did not inhibit the fungal growth.
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| 6. |
- Bardage, Stig, et al.
(författare)
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The effect of natural product treatment of southern yellow pine on fungi causing blue stain and mold
- 2014
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305 .- 1879-0208. ; 86:B, s. 54-59
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Tidskriftsartikel (refereegranskat)abstract
- Blue stain and mold growth on wood can be aesthetically unappealing, but mold growth can also potentially trigger health related issues. In this study, a screening of the effect of selected natural products and derivatives of natural products including essential oils, plant based monomers, and shellfish exoskeleton compounds on the inhibition of blue stain fungi and mold fungi in southern yellow pine veneers and cellulose filter paper. The treatment of the substrates, the weight percent gain of the natural products, and the inhibition effect is presented. The natural products have been investigated previously, but most have not been applied to wood or investigated with regards to blue stain or mold growth. The specimens were treated by dipping, wrapping in foil, and then heating at 105°C for 24h in order to encourage reaction or grafting of the natural products to the wood. A selection of seven additives each exhibited significant protection against blue stain colonization in Petri dish tests and these were studied more in-depth. These included tea tree oil, propyl gallate, hydrogenated gum oil, salicylic acid, cinnamon bark oil, butylene oxide, and furfural. The salicylic acid, tea tree oil, and cinnamon bark oil had the least amount of mold growth after four weeks in the mold chamber test, and have been previously reported to have a mechanism of antifungal activity resulting from their ability to disrupt the fungal cell wall. Propyl gallate veneer was the only specimen that had a lower pH and that would be considered unfavorable to mold growth. While furfural, salicylic acid, and cinnamon bark oil treated veneers all had more hydrophobic surfaces when compared to untreated wood.
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| 7. |
- Björdal, Charlotte, 1961, et al.
(författare)
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Bacterial degradation of nine wooden foundation piles from Gothenburg historic city center and correlation to wood quality, environment, and time in service
- 2021
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305. ; 164
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Tidskriftsartikel (refereegranskat)abstract
- Nine wooden foundation piles of spruce and pine supporting historic buildings in the old town of Gothenburg, Sweden, were examined for fungal and bacterial degradation. The aim was to assess the type and degree of decay of the pile heads and correlate variations to the local environment, time in service and the wood quality. Soil and water samples were measured in the field for basic hydrogeological analyses, and pH, redox, O2 and groundwater level. The piles showed strong similarities in decay. Detailed light microscopy examination revealed that solely erosion bacteria caused degradation; both in outermost soft layers of the sapwood and further inwards. Most severe decay was present in the outermost layers, 1-3 cm, thereafter decay generally decreased and stopped at varying depths. Most piles had sound interior wood tissue, but a few were superficially to moderately degraded throughout. Some piles showed pronounced variation in degree of decay at the north respectively south side of the stem. This might be related to local water flow directions in the soil. In two piles, minor decay by white rot and soft rot were observed. Soft rot attacks were concluded to be of older date, most likely related to the time of construction, whereas white rot either infected the wood during an aerobic period; e.g. extreme drainage of unknown date, or alternatively the attack developed already in the living tree before felling. Despite that all pile heads (except one) were exposed below groundwater level and mainly in compact clay soil with low redox values, it was not possible to correlate any specific environmental parameter from soil and pore water analyses to the observed decay rates. Diameter of the pile and time in ground were the only two factors clearly correlated to the long-term performance of the piles in this specific urban environment.
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| 8. |
- Björdal, Charlotte, 1961, et al.
(författare)
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Correlation between sulfur accumulation and microbial wood degradation on shipwreck timbers
- 2019
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305. ; 140, s. 37-42
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Tidskriftsartikel (refereegranskat)abstract
- Archaeological shipwreck timber often contains elevated amounts of sulfur and iron rich compounds, accumulated during the long-term exposure in marine environments. This paper investigates if the accumulation of iron and sulfur is correlated and restricted to areas where microbial wood degradation takes place. Examination of microbial degradation in two pine and four oak samples from three historical shipwrecks situated in the Baltic Sea are carried out by light microscopy. Type, degree and amount of wood degradation by fungal and bacterial processes is compared to results on sulfur and iron accumulation studied by X-Ray Fluorescence (XRF) scanning. The highest accumulation of iron and sulfur is found in the surface layers (0–2cm), where microbial degradation is also most intense. A novel finding is that both decay by erosion bacteria- and soft rot fungi promotes accumulation. Our results also imply that accumulation of inorganic sulfur and iron in archaeological wood involves several different processes which might include solely chemical as well as biogeochemical processes. The processes are different in pine compared to oak and the wood species of the shipwreck timber might therefore have a more important role than previously assumed.
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| 9. |
- Björdal, Charlotte, 1961, et al.
(författare)
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Evaluation of in situ preservation method applied at a terrestrial archaeological shipwreck site by use of sacrificial wood samples installed for 25 years
- 2023
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier. - 0964-8305 .- 1879-0208. ; 176
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Tidskriftsartikel (refereegranskat)abstract
- In 1995 remains of a 13th century shipwreck, “the Kronholmen cog”, was discovered in sandy soil at a golf green on the island of Gotland, Sweden. Prior to backfilling and in situ preservation, four sacrificial wood samples (SWS) of sound pine sapwood were installed for long-term monitoring of wood decaying processes. In year 2020, the site was re-opened to evaluate the protective nature of the site. All SWS and six archaeological samples were taken for a comparative analysis. Observations by light- and scanning electron microscopy showed severe microbial decomposition by fungi and bacteria. Based on occurrence of decay forms in the wood fibres, soft rot (SR) was identified as the main degrader of both SWS and in the first 2 cm of the heavily eroded archaeological material, accompanied by bacteria (type tunnelling bacteria (TB)). Moderate decay by bacteria (type erosion bacteria, EB) in archaeological samples indicated longer period during the last 700 years under waterlogged and anaerobic condition – e.g., protective. Only initial decay of erosion bacteria (EB) was observed in SWS, strongly indicating a non-protective environment during the last 25 years. Severe brown rot decay was established in SWS and archaeological wood located in the front of the wreck where burial conditions were most critical (0.5 m above groundwater level, and 0.4 below soil/air interface). Here, a total of 0.50 cm surface layer of SWS was lost, yielding an initial decay rate of 20% in 25 years. In general, surfaces were heavily attacked especially for archaeological samples, and plant roots penetrated the soft and degraded surface layer. We conclude that the site since backfilling in 1995 has been semi-oxygenated and has promoted more severe fungal decomposition of cultural heritage. Thus, the site is not able to protect and preserve the precious archaeological remains for future generations and actions must be taken. SWS are concluded to be an important technique for long term monitoring of archaeological sites preserved in situ.
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| 10. |
- Björdal, Charlotte, 1961
(författare)
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Evaluation of microbial degradation of shipwrecks in the Baltic Sea
- 2012
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305. ; 70, s. 126-140
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Tidskriftsartikel (refereegranskat)abstract
- Unique historical shipwrecks in the Baltic Sea are exposed to continuous decay by specialised wood-degrading microorganisms. In this comprehensive literature study, current knowledge on microbial degradation in aquatic environments is synthesised and adapted to a cross-disciplinary context, to further understanding of the ongoing decay processes in shipwreck timbers today. Soft-rot fungi and erosion bacteria are the two most active groups of wood degraders. Their decomposition of the wood surface and interior are described, discussed, and finally compared with the available data from examined shipwrecks found in the Baltic Sea. The rate of decay depends on several parameters, such as wood species, environmental factors, duration of exposure (age of object), sediment protection, and physical damage. More consistent predictions on the longevity of wrecks are dependent on future research on the ecology of the microbes, combined with investigations of the historical wrecks themselves. This research is essential for successful in-situ protection and long-term preservation of significant historical shipwrecks.
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