Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2009
Abstract
Mechanical strength properties are the most important feature of wood in constructions. In decaying wood strength loss can precede mass loss. Hence, both in laboratory and outdoor applications non-destructive measurement methods for early decay detection are in demand. The aim of this study was to evaluate the applicability of ultrasonic pulse propagation as a tool for decay detection in different laboratory setups. A dynamic MOE (MOEdyn) strength test device based on measurement of ultrasonic pulse propagation was used for non-destructive strength evaluation in different exposure situations for Scots pine sapwood. Two different test setups were used. In the first test MOEdyn was measured above fibre saturation. A range of different wood protection treatments were tested according to the terrestrial microcosms (TMC) test, a modified ENV 807. Three different soil types were used: forest soil dominated by white rot, Simlångsdalen test field soil dominated by brown rot and compost soil characterised by a mixture of bacteria and soft rot. Before strength testing the samples were water saturated and MOEdyn was measured above the fibre saturation point at time intervals (0, 8, 16, 24, 32 and 40 weeks) using ultrasound. Comparisons of strength loss were performed between treatments in the different soil types, and strength loss was also compared with mass loss. In the second test MOEdyn were measured below fibre saturation. Ultrasound measurements were performed on 0.5 m pine logs sampled from five trees from the same stand in central Southern Norway. Logs from two of the trees had varying amounts of discoloration due to an incipient attack by the white rot fungus Phlebiopsis gigantea during storage. Amount of visible discoloration had effect on MOEdyn values from measurements on log ends. Transversal measurement of MOEdyn was not successful. In a subsequent water uptake test, logs with discoloration absorbed substantially more water than the rest of the sample. The conclusion of this study was that the use of ultrasonic MOE is applicable as an evaluation tool in early decay detection.
Authors
Jørn-Frode NordbakkenAbstract
Det er ikke registrert sammendrag
Authors
R. Wu W. L. Guo X. R. Wang X. L. Wang T. T. Zhuang jihong liu clarke B. LiuAbstract
Genetic instability could be provoked as an unintended consequence of genetic engineering in plants. Here we report that the rice endogenous long terminal repeat (LTR) retrotransposon Tos17 was transpositionally activated only in transgenic calli and their regenerated plants produced by biolistic transformation in rice (Oryza sativa L.) ssp. japonica cv. Matsumae. Moreover, the transpositional activity of Tos17 was sustained after plant regeneration in the T0 generation, and produced new germinal insertions. In contrast, the element remained totally quiescent in calli and regenerated plants from tissue culture of this genotype. Nonetheless, transcriptional induction and cytosine demethylation of Tos17 were found to have occurred with no significant difference in both kinds of calli, tissue culture alone and transgenic. This suggests that callus culture is likely to have played an important role in destabilizing Tos17 in the direction towards transpositional activation, but that biolistic transformation is the direct causal factor.
Authors
R Wu W. L. Guo X. R. Wang X. L. Wang T. T. Zhuang jihong liu clarke B. LiuAbstract
Genetic instability could be provoked as an unintended consequence of genetic engineering in plants. Here we report that the rice endogenous long terminal repeat (LTR) retrotransposon Tos17 was transpositionally activated only in transgenic calli and their regenerated plants produced by biolistic transformation in rice (Oryza sativa L.) ssp. japonica cv. Matsumae. Moreover, the transpositional activity of Tos17 was sustained after plant regeneration in the T0 generation, and produced new germinal insertions. In contrast, the element remained totally quiescent in calli and regenerated plants from tissue culture of this genotype. Nonetheless, transcriptional induction and cytosine demethylation of Tos17 were found to have occurred with no significant difference in both kinds of calli, tissue culture alone and transgenic. This suggests that callus culture is likely to have played an important role in destabilizing Tos17 in the direction towards transpositional activation, but that biolistic transformation is the direct causal factor.
Abstract
Det er ikke registrert sammendrag
Abstract
Due to the exponential increase in production of engineered nanomaterials, concerns are raised about their inevitable spreading and fate in the environment. In this study we examined the uptake and excretion kinetics of cobalt and silver nanoparticles (NPs) in Eisenia fetida, as well as their internal distribution within earthworms. We hypothesised that the uptake, retention time and internal distribution of cobalt and silver depend on their speciation, i.e. whether they are absorbed as ions or nanoparticles. Nanoparticles were subjected to neutron activation prior to the experiment, in order to facilitate tracing and quantification in earthworms by gamma counting and autoradiography. Ions and NPs were added to the food, horse manure (HM). The treatments were Co2+ 0.70 µg/kg HM, CoNP 0.69 mg/kg HM, Ag+ 0.54 mg/kg HM, AgNP 0.45 mg/kg HM, and control. The experiment followed the OECD guidelines, with one month uptake and two months excretion for silver treatments, and four months excretion for cobalt treatments. The patterns of accumulation were highly different for cobalt and silver. The concentration ratios (Bq/g worm / Bq/g food) after one month uptake were 0.93 ± 0.36 and 2.02 ± 0.65 for CoNP and Co2+ respectively, and almost all absorbed CoNP and Co2+ remained within the worms after 4 months excretion. The Ag concentration ratios after one month uptake were 0.015 ± 0.016 and 0.054 ± 0.024 for AgNP and Ag+ respectively, with a subsequent excretion of almost all AgNP and Ag+ within a few days. In addition to information on uptake and excretion kinetics, gamma counting on individual organs, coupled to autoradiography on worm transects gave information on distribution of cobalt and silver NPs within the body, and the target organs for these NPs.
Authors
Gunhild BørtnesAbstract
Det er ikke registrert sammendrag
Authors
Tatsiana EspevigAbstract
One of the major concerns for the use of velvet bentgrass (Agrostis canina) in Scandinavia is whether current cultivars have sufficient winter hardiness. To meet this challenge, velvet bentgrass (VB) cultivars were tested for winter hardiness in controlled environments at UMB during 2006/2007. Hardened and unhardened VB cultivars Avalon, Villa, Greenwich and Legendary were compared with creeping bentgrass (CB, Agrostis stolonifera) cv. Penn A-4 (control) for freezing tolerance. There were no differences in freezing tolerance between velvet and creeping bentgrass, but none of the tested cultivars, whether hardened or not, tolerated freezing to - 9 ºC or lower.That became a background for the collaborative project between the Norwegian Institute of Agricultural and Environmental Research (Bioforsk), Norwegian University of Life Science, Rutgers University and the University of Massachusetts. The objectives of the project would be: (1) to compare freezing tolerance of VB and CB, (2) to quantify carbohydrate changes during the two consecutive phases of cold acclimation in these species, and (3) to compare one direct and two indirect methods for determination of LT50 in turfgrasses.
Authors
Tatsiana EspevigAbstract
Preliminary results from the study "Effects of metabolic changes during cold hardening on freezing survival of Agrostis spp." were presented. The objectives of the trial were: (1) to compare freezing tolerance of velvet bentgrass and creeping bentgrass, (2) to quantify carbohydrate and protein changes during the two consecutive phases of cold acclimation in these species, and (3) to compare one direct and two indirect methods for determination of LT50 in turfgrasses. Three (of four) treatments representing different phases of cold acclimation were compared: (i) nonacclimated (NA) plants maintained at 18 °C/12 °C (day/night); (ii) plants acclimated at 2 °C for 2 wk and 250 μmol m-2 s-1 for 12 h photoperiod (A2); and (iii) as treatment (ii) but for 4 wk (A4). Plants exposed to additional sub-zero acclimation in the dark at -2 °C for 2 wk (A4+SZA2) were under acclimation treatment at that time. Results regarding 1st and 3rd objectives were discussed. Acclimation at 2 ºC significantly improved freezing tolerance of both species, but differences between species were not significant. The LT50 for plants subjected to A2 and A4 were 4 and 6 °C lower, respectively, compared to NA plants. Crown viability test had a good correlation with the LT50 based on whole plant survival. Electrolyte leakage underestimated freezing survival ability in Agrostis spp.
Abstract
Results from the study "Effects of metabolic changes during cold hardening on freezing survival of Agrostis spp." were presented. The objectives of the trial were: (1) to compare freezing tolerance of velvet bentgrass and creeping bentgrass, (2) to quantify carbohydrate and protein changes during the two consecutive phases of cold acclimation in these species, and (3) to compare one direct and two indirect methods for determination of LT50 in turfgrasses. Four treatments representing different phases of cold acclimation were compared: (i) non-acclimated (NA) plants maintained at 18 / 12 °C (day/night); (ii) plants acclimated at 2 °C for 2 wk (A2); (iii) plants acclimated at 2 °C for 4 wk (A4); and (iv) plants acclimated at 2 °C for 4 wk with an additional sub-zero acclimation in the dark at -2 °C for 2 wk (A4+SZA2). Velvet bentgrass and creeping bentgrass showed no difference in lethal temperatures for 50% of the test population (LT50) as estimated by whole plant survival. Treatments A2 and A4 resulted in accumulation of sucrose and fructans, and significantly lowered LT50 as compared with NA. A4+SZA2 resulted in less fructans, no difference in sucrose and higher concentration of reducing sugars but LT50 was not lower than after A4 treatment. Crown viability determined by reduction of tetrazolium chloride showed close correlation with LT50 values based on whole plant survival. Electrolyte leakage produced less consistent results and cannot be recommend as a quick method for evaluation of relative hardiness of the rather small crowns of bentgrass species, especially not if acclimation at subfreezing temperatures is part of the testing procedure.