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.
2012
Abstract
Fungal decay considerably affects the macroscopic mechanical properties of wood as a result of modifications and degradations in its microscopic structure. While effects on mechanical properties related to the stem direction are fairly well understood, effects on radial and tangential directions (transverse properties) are less well investigated. In the present study, changes of longitudinal elastic moduli and stiffness data in all anatomical directions of Scots pine (Pinus sylvestris) sapwood which was degraded by Gloeophyllum trabeum (brown rot) and Trametes versicolor (white rot) for up to 28 weeks have been investigated. Transverse properties were found to be much more deteriorated than the longitudinal ones. This is because of the degradation of the polymer matrix between the cellulose microfibrils, which has a strong effect on transverse stiffness. Longitudinal stiffness, on the other hand, is mainly governed by cellulose microfibrils, which are more stable agains fungal decay. G. trabeum (more active in earlywood) strongly weakens radial stiffness, whereas T. versicolor (more active in latewood) strongly reduces tangential stiffness. The data in terms of radial and tangential stiffnesses, as well as the corresponding anisotropy ratios, seem to be suitable as durability indicators of wood and even allow conclusions to be made on the degradation mechanisms of fungi.
Authors
Apolline Auclerc Johanne Nahmani Delphine Aran Virgine Baldy Henry Callot Charles Gers Etienne Iorio Emmanuel Lapied Aurore Lassauce Alain Pasquet Jörg. Spelda Jean-Pierre Rossi Francois GueroldAbstract
No abstract has been registered
Abstract
Groundwater pollution by agrochemicals, degradation of soil quality and pollution of aquatic ecosystems by agricultural drainage waters have become an issue in the last decades. Flow processes in the vadose zone are closely related to these problems. In general, water flow in soils can be classified into two major categories: uniform and non-uniform (preferential) flow (In: U.S. National Committee for Rock Mechanics, Conceptual Models of Flow and Transport in the Fractured Vadose Zone, 2001, pp.149-187). The former describes a relatively slow movement of water through the porous soil matrix and can be modelled by Richard”s equation. The latter comprises all flow types where water bypasses a portion of the soil matrix and flows through localised (i.e. preferential) paths. Unlike uniform flow, preferential flow is hardly predictable because the assumptions of Richard”s equation of a homogeneous representative elementary volume characterised by a single value of water potential, water content and hydraulic conductivity are frequently violated (Eur J Soil Sci, 2007; 58:523-546)....
Abstract
The relative frequency of Therrya fuckelii and T. pini fruiting on dead branches of Scots pine was investigated in southern Norway by examining lightning-damaged and wind-fallen trees, randomly collected branches and Nordic herbarium collections of these ascomycetes representing the order Rhytismatales. Ascus, ascospore, and subhymenium characteristics were used as criteria for species identification, while a sequence analysis of ITS rDNA gene cluster was performed to compare the relatedness of the species to each other and to corresponding fungal sequences available at the NCBI GenBank Sequence Database. In a few cases, the two Therrya species co-occurred on the same branch, but in general, whether field or herbarium material, T. fuckelii was clearly more common than T. pini.Within the Nordic countries, both species occurred throughout the natural distribution area of Scots pine. The ITS rDNA sequence of T. pini strains was 91% similar to T. fuckelii strains, the differences locating both within the internal transcribed spacers ITS1 and ITS2 and the 5.8 S rDNA gene. More variation in the ITS1-5.8S-ITS2 sequence was observed among T. pini than T. fuckelii samples; genetic implications of this finding are discussed. Upon sequence analysis, we discovered that a T. pini sequence has been deposited in the NCBI GenBank under a false identity. We emphasize the importance of co-examining strains that originate from mature fruit bodies with fully developed morphologic features as reference samples.
Authors
Christian Guido Bruckner Kerstin Mammitzsch Günter Jost Juliane Wendt Matthias Labrenz Klaus JürgensAbstract
Pelagic marine oxygen-depleted zones often exhibit a redox gradient, caused by oxygen depletion due to biological demand exceeding ventilation, and the accumulation of reduced chemical species, such as hydrogen sulfide. These redox gradients harbour a distinct assemblage of epsilonproteobacteria capable of fixing carbon dioxide autotrophically in the dark and potentially of utilizing hydrogen sulfide chemolithotrophically by oxidation with nitrate. Together, these two processes are referred to as chemolithoautotrophic denitrification. The focus of this study was the recently isolated and cultivated representative strain of pelagic epsilonproteobacteria, 'Sulfurimonas gotlandica' strain GD1, specifically dark carbon dioxide fixation and its substrate turnovers during chemolithotrophic denitrification. By connecting these processes stoichiometrically and comparing the results with those obtained for dark carbon dioxide fixation and nutrient concentrations measured in pelagic redox gradients of the Baltic Sea, we were able to estimate the role of chemolithoautotrophic denitrification in the environment. Evidence is provided for a defined zone where chemolithoautotrophic denitrification of these epsilonproteobacteria allows the complete removal of nitrate and hydrogen sulfide from the water column. This water layer is roughly equivalent in thickness to the average overlapping region of the two substrates, but slightly larger. Such a difference may be explained by a variety of reasons, including, e.g. utilization of substrates present at concentrations below the detection limit, alternative usage of other substrates as thiosulfate or nitrous oxide, or comparable activities of other microbes. However, the combined results of in vitro and in situ studies strongly suggest that epsilonproteobacteria are primarily responsible for hydrogen sulfide and nitrate removal from pelagic Baltic Sea redox gradients.
Authors
Venche TalgøAbstract
No abstract has been registered
Authors
Sekhar Udaya NagothuAbstract
No abstract has been registered
Authors
Trond RafossAbstract
No abstract has been registered
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No abstract has been registered
Abstract
No abstract has been registered