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.
2008
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Authors
Hege HovdAbstract
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A major challenge in studies on the environmental fate of nanoparticles is to detect their presence and distinguish them from natural nanoparticles and the large variety of amorphous materials present in environmental media. Neutron activation of mineral particles enables the production of radio-labelled NPs without surface modification, and enabling both localisation and quantification within a matrix or organism. The method is extremely sensitive, allowing detection at parts per billion or lower. Thus, any such labelled NP can be detected in individual fractions or compartments in soil or sediments (associated to clay, colloids, humic material, etc) or localized within organisms and their specific tissues following dissection (fish gills, digestive tract, liver, brain, etc) or by autoradiography. An added advantage of gamma-emitting radionuclides is that they do not need separation from the matrix for counting, thus uptake and extraction can be followed on live animals. Thus time-course experiments in vivo may be conducted to study metabolism and exposure, two aspects that are currently lacking in the body of ecotoxicological knowledge about ENPs. This paper will report some of the conditions, advantages and experimental opportunities of using neutron activation as a tool to study ENPs in environmental samples, with demonstration of the application of the technique in studies on Ag and Co nanoparticle uptake and metabolism in the earthworm Eisenia fetida.
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In Norway, public procurement of food to youth is not well developed in comparison to many other European and Scandinavian countries. School meals are only offered in very few primary schools, and the common school meal is a packed lunch (sandwiches) brought from home, consumed in the class room. Subscription schemes for milk were introduced around 1970, and for fruit around 1995. Organic milk and fruit is offered only in some regions. Since 2007, fruit is served without payment in all schools with a lower secondary level (class 8-10 or 1-10). This effort was introduced as a first step to develop a free school meal in all public schools, which is a goal of one of the political parties in the current government. As in many other European countries, free school meals were offered (especially to poor children) in schools in the larger Norwegian cities around 1900. However, these meals were criticised for being unhealthy, and replaced by whole grain bread, milk and vegetables around 1930. Increasing private wealth, and increased demand for investments in school buildings, books etc changed the public priority and free school meals disappeared in Oslo around 1960. Today, there is not a general agreement about the optimal school meal composition, and whether or not the meals should be funded by the public. However, the increasing length of the school day and unsatisfactory scores of Norwegian pupils in international comparison tests (e.g. PISA) makes the school meal sector highly relevant in the public debate. Three cases that will be studied in a research project about public organic food procurement for youth are briefly described: The municipality of Trondheim, Øya music festival in Oslo and the Air Force Academy. (Increased) serving of organic food is an important aim in all these cases, and young people are an important target group. The report is produced within the project “innovative Public Organic food Procurement for Youth”, iPOPY, and will be updated and revised during the project period (2007-2010).
Authors
Arvid Steen Turid Strøm Aksel BernhoftAbstract
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To evaluate overwintering strategies of the fungus Neozygites floridana, an important natural enemy of Tetranychus urticae, hibernating T. urticae females were investigated for the presence of fungal structures throughout one winter (October 12, 2006 to February 19, 2007) in field-grown strawberries in a cold climate in Norway ( min. ambient temp -15.3 degrees C). Neozygites floridana was present as hyphal bodies inside live, hibernating females in T. urticae populations throughout the sampling period. The lowest percentages of hibernating females with hyphal bodies were found at the two first dates of sampling at 5.5 and 0% on October 12 and 19, respectively. The prevalence then increased and peaked at 54.4% on January 14. Resting spores (immature) were also found in live hibernating females at some dates, but at lower prevalence than for hyphal bodies and predominantly only until November 8. Prevalence of resting spores in live hibernating females ranged from 2.5 to 13.8%. Total number of T. urticae was also recorded, and most mites of all four categories (nymphs, males, non-hibernating and hibernating females) were found at the first sampling date. At this date non-hibernating females were the most abundant. A sharp decrease in non-hibernating females, nymphs and males was, however, seen from mid-October to mid-November; also numbers of hibernating females decreased, but not as fast. The relative abundance of hibernating females compared to non-hibernating females increased from 32.2% at the first collection (October 12) to 97.7% at the last collection (February 2). This study confirms that N.floridana survives the winter as a semi-latent hyphal body infection, protected inside live hibernating females. It is therefore ready to develop and sporulate as soon as climatic conditions permit, resulting in early season infection of T. urticae.
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No abstract has been registered