Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2005
Abstract
Fungi cause serious problems in wood utilization, and environmentally benign wood protection is required as an alternative to traditional chemicals. Chitosan has shown promising antimicrobial properties against several microorganisms. In this study, we present the characterization of and antifungal properties of a commercial chitosan formulation developed for impregnation of wood.A broad range of chemical and mycological methods were used to evaluate the uptake, fixation, and antifungal properties of chitosan for wood preservation. The results show that the higher the uptake of chitosan the lower the relative recovery of chitosan in wood after leaching, and the higher the molecular weight of chitosan the higher the recovery.Chitosan with high molecular weight proved to be more efficient against decay fungi than chitosan with low molecular weight. The fungi tested on chitosan-amended nutrient agar medium were totally inhibited at 1% (w/v) concentration.In decay studies using small wood blocks, 4.8% (w/v) chitosan concentration gave the best protection against brown rot fungi.
Abstract
During a period of 2 years and 3 months (1 January 2001 - 20 March 2003) Mycoteam had 3161 consultations in buildings in southern Norway, 1428 revealing damage from decay fungi. One consultation often revealed several occurrences of fungi, and the total number of occurrences of decay fungi was 3434. Thirty-five different species/genera/groups of decay fungi were recorded. During this period brown rot was more frequent (77.4 %) than soft rot (19.2 %) and white rot (3.4 %). Coniophora puteana (16.3 %) and Serpula lacrymans (16 %) were the most frequently identified species. Different species of the genus Antrodia were recorded in 18.4 % of the occurrences, while the group Corticiaceae accounted for 5.7 % and soft rot for 15.8 %. Investigations of damaged structural parts of buildings showed that decay fungi were most common in walls (18.3 %). Floor damage accounted for 13.4 % of the damaged structures and roofs for 8.8 %. Nearly all species and groups of the investigated fungi were most common indoors. Gloeophyllum sepiarium on the other hand was most common outdoors, and Dacrymyces stillatus was exclusively found outdoors. The Norwegian data were compared with published time series data from Denmark (1946-66, 1966-71, 1974-75, 1982) and Finland (1978-84, 1985-88). S. lacrymans and C. puteana were the most frequent species in these datasets too. Antrodia spp. were also common in the Finnish reports, but barely recorded (as identified species) in Denmark. In both the Danish and the Finnish data, damage to floors is the most frequently recorded structural damage in buildings.
Abstract
This paper describes the use of quantitative real-time PCR for monitoring colonization of birch wood (Betula pubescens) by the white-rot fungus Trametes versicolor in an EN113 decay experiment. The wood samples were harvested after 4, 8, 12, 16 and 20 weeks of incubation.The mass loss was in the range of 440%. Chitin and ergosterol assays were conducted for comparison. Second-order polynomial fits of the mass loss of decayed wood versus chitin, ergosterol and DNA gave correlations (r2) of 0.87, 0.61 and 0.84, respectively. Compared to the other two assays employed, real-time PCR data correlated best with the relative mass loss of decayed samples 48 weeks after inoculation, while the saturation and decline of DNA-based estimates for fungal colonization 1620 weeks after inoculation indicated that the DNA assay is not suited for quantification purposes in the late stages of decay.The impact of conversion factors, extraction efficiency, inhibitory compounds and background levels in relation to the three detection assays used is discussed.
2004
Abstract
A method for determination of the climate gases CH4, CO2 and N2O in air samples and soil atmosphere was developed using GC-MS. The method uses straightforward gas chromatography (separation of the gases) with a mass spectrometric detector in single ion mode (specific determination).The gases were determined with high sensitivity and high sample throughput (18 samples h1). The LOD (3) for the gases were 0.10 L L1 for CH4, 20 L L1 for CO2 and 0.02 L L1 for N2O. The linear range (R2 = 0.999) was up to 500 L L1 for CH4, 4000 L L1 for CO2 and 80 L L1 for N2O. The samples were collected in 10 mL vials and a 5 L aliquot was injected on column.The method was tested against certified gas references, the analytical data gave an accuracy within 5% and a precision of 3%. The presence of 10% by volume of C2H2 (often used experimentally to prevent N2 formation from N2O) did not interfere with detection for the targeted trace gases.
Abstract
A home designed diffusion chamber was used during the isolation of fluoride from plant material. The chamber contained two beakers, one for the sample (milled plant material) and the other for the trapping solution (0.1M NaOH). Hexamethyldisiloxane (HMDS) in 3.5M perchloric acid was added into the sample beaker through a septum, after the chamber was closed.Fluoride in the sample reacts with HMDS and forms the volatile trimethylfluorosilane (TMFS), which is trapped and hydrolyzed to fluoride. The diffusion time was 2h and 20 samples were handled at the same time. The fluoride concentration was determined by a flow injection analysis (FIA) system using an ion selective electrode (about 50 samples/hour).The results by acid extraction were compared to the results obtained after an ashing/alkaline fusion. Both a certified sample of timothy grass (NIST 2695, high level) and more typical vegetation from forest were analyzed. For the timothy grass, the recovery increased from 48 to 84% when ashing/alkali fusion was used before the diffusion. However, higher recovery was not obtained by using ashing/alkaline fusion for the determination of fluoride in natural vegetation from forest. Acid extraction in combination with addition of HMDS was sufficient as pretreatment in these types of plant materials.The method was routinely used for the determination of fluoride both in research and forest monitoring.
Abstract
In this study modified linseed oils, rape oil and three waxes were screened on their efficacy as wood protecting agents. By testing all products when impregnated with high retentions in Scots Pine sapwood on water repellence qualities, additionally an accelerated weathering test, drying quality, accelerated brown rot and blue stain test, an indication is formed of the capability of these products as wood protecting treatments. All oil and wax treatments significantly improve the water repellency of untreated wood. In weathering resistance, maleinised and polymerised linseed oil showed the best results in improving untreated pine sapwood dimensional stability thus reducing crack formation and decolourization by UV-light. In accelerated brown rot and blue stain tests boiled linseed oil significantly reduced degradation and staining. In addition, maleinised linseed oil and a mixture of modified linseed- and mineral oil are very well performing in the blue stain test. Overall most promising products are the maleinised oils and boiled linseed oil. The maleinised oils have good potentials in long lasting water repellency, showed some fungal growth prevention, are colour stable in weathering tests and create a dimensional stable wood product. Boiled linseed oil is not exceptionally good as a water repellent, but the good drying qualities together with easy handling makes this oil a promising product.
Abstract
Artikkelen drøfter saltinnhold i ulike bygningsdeler i Bryggen i Bergen, saltets opphav og betydning i forhold til bevaring av trevirket. Ulike nedbrytningsorganismer i saltholdig tømmer er også vurdert.
Abstract
Tall oil is a by-product in pulping of resinous wood by the sulphate process. Tall oil contains a complex mixture of wood extractives. Some of these extractives act as natural protection against wood decaying fungi while other serve as nutrition for the fungi. This report describes a screening of the efficacy of four refined tall oils with different chemical composition on wood decaying fungi.Testing was performed as filter paper assay and mini-block assay. In the filter paper assay growth rates of the white rot fungus Coriolus versicolor and the brown rot fungus Poria placenta were inhibited by the tall oils. None of the oils caused total inhibition of the fungi but there was a clear pattern towards increased efficacy with increased portion of resin acids in the oils.Impregnated mini-blocks with approximately 200 kg/m3 retention of tall oil after leaching showed an evident effect against Coniophora puteana and Poria placenta compared to untreated control samples. However, using the criteria from EN 113 requiring less than 3% mass loss, tall oil failed.The results indicate that decay resistance of tall oil impregnated Scots pine sapwood to the retention level used in this study is comparable with the decay resistance of Scots pine heartwood. It was expected that the efficacy of the tall oils was related to chemical composition of the oils. This was confirmed for the filter paper assay where the efficacy increased with increasing amount of resin acids. However, this pattern was not found for the mini-block assay.The protective effect of the tall oils in wood seems therefore to be more related to their hydrophobic properties than to their fungicidal properties.
Abstract
Chitosan, a derivate of the natural amino polysaccharide chitin, has proven effective as a potential environmentally benign antimicrobial component. Few studies have focused on chitosan applied to wood against wood inhabiting and decaying fungi.In these screening studies several mycological experiments were performed to screen chitosan as a potential wood protecting agent. Growth studies on chitosan-amended media showed total inhibition of Poria placenta, Coriolus versicolor and Aspergillus niger using 1% w/v concentration.Chitosan with high average molecular weight (MW) was more efficient against mould and staining fungi than chitosan with low MW. Agar plate leaching tests showed only a small leaching effect using a 5% concentration on A. niger and P. placenta. Decay testing with P. placenta demonstrated efficacy using 5% and 2.5% concentrations in unleached samples. Leaching decreased the efficacy of chitosan and further investigations are needed to improve the fixation in wood.
2003
Authors
Dominik Röser Antti Asikainen Simen Gjølsjø B. Jaskelevicius D. Johansson P. Jylhä L. Kairiukstis I. Konstantinova Jørn Kristian Lileng Anders Lunnan M. Mandre Juha Nurmi H. Pärn T. Saksa L. Sikanen Kjell Suadicani M. Totopainen L. VilkristeAbstract
The report is investigating the current state of forestry, forest industries and the bioenergy sector in Denmark, Estonia, Finland, Latvia, Lithuania, Norway and Sweden. The main task of the research is to illustrate the current supply and use of wood based fuels in the Baltic and Nordic countries. Additionally the present use of forest fuels in the different countries in the private and industrial sector is analyzed and bottlenecks in the current supply of forest fuels are identified. The focus on energy policy has been on energy systems with less CO2 emissions in order to meet requirement of international agreements. Therefore, forest fuels offer great potential as a source of renewable energy. There has been a steady increase in the growing stock of European forests. Large amounts of residues are left unutilised both in Nordic and Baltic forests, especially in first thinnings and intermediate cuttings. They offer large potential to further increase the share of wood fuels in total energy consumption. Forest industries utilize a great share of wood residues at present but especially in Baltic regions there is potential to intensify the use of wood residues. An additional increase in wood biomass utilization is also dependent on future expansion of the district heating networks in Nordic and Baltic countries. Potential is available especially in the Baltic countries and Norway. The situation in regards to utilization of wood biomass in private dwellings is similar in all seven countries. Large amounts of fuelwood are consumed annually but new furnace and burner technology is necessary to use resources more efficiently. In regards to energy policy a lot has been done to improve the use of biomass utilization, but more has to be done to strengthen the position of forest fuels in the future. The main bottlenecks for the larger use of forest biomass were found to be a lack of utilisation of available technology for harvesting and transport operations and a lack of district heating. An improved use of technology would decrease the price of forest fuels, necessary to compete with fossil fuel prices on international markets.