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- Hjörnhede, Anders, 1968, et al.
(författare)
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Erosion-corrosion of laser and thermally deposited coatings exposed in fluidised bed combustion plants
- 2006
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Ingår i: Materials and Corrosion. ; 57:4, s. 307-322
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Tidskriftsartikel (refereegranskat)abstract
- Coated steel tubes were exposed in two power plants (CFB and PFBC) fired with wood chips and coal with a small addition of olive seeds, respectively. Laser coating and two thermal spray techniques were used. The samples in the PFBC plant were immersed in the fluidising bed at material temperatures 450 °C and 400 °C. The exposure lasted for a total time of 8089 h. In the CFB plant a probe at the cyclone entrance had a material temperature of 630 °C for the first 2100 h and then 480 °C for 920 h. The material wastage was determined from tube cross-sections. The corrosion products and deposits were analysed by SEM/EDX, Auger spectroscopy, XPS and XRD. Cobalt based coatings show the best performance in both plants, while nickel based coatings are very sensitive to erosion but resistant to a corrosive atmosphere. The totally degraded chromium carbide containing coating in the CFB plant shows that the degree of corrosion is much larger in this environment. The same coating was excellent in the fluidised bed due to its high erosion resistance. The material wastage is independent of the deposition method. The coating technicques had no significant effect on the spallation behaviour.
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| 6. |
- Bignert, Anders, et al.
(författare)
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Övervakning av metaller och organiska miljögifter i marin biota, 2011
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The environmental toxicants examined in this report can be classified into five groups –heavy metals, chlorinated compounds, brominated flame retardants, polyaromatichydrocarbons and perfluorinated compounds. Each of these contaminants has beenexamined from various sites for up to six different fish species, in blue mussels, and inguillemot eggs, for varying lengths of time. The following summary examines overalltrends, spatial and temporal, for the five groups.Condition and Fat ContentCondition and fat content in different species tended to follow the same pattern at the samesites, with a few exceptions. Most of the fish species generally displayed a decreasing trendin both condition and fat content at most sites examined. Exceptions to this were increasesin fat content seen in herring (the last ten years) and cod at Fladen; an increase in conditionfor herring at Ängskärsklubb in spring; and in perch, a decrease in fat content atKvädöfjärden but no trend in condition for the same site.Heavy MetalsDue to a change in methods for metal analysis (not Hg) in 2004, values between 2003 and2007 should be interpreted with care. From 2009 metals are analyzed at ITM, Stockholmuniversity.The longer time series in guillemot egg and spring-caught herring from the southernBothnian Sea and southern Baltic Proper show significant decreases of mercury. Theherring site in the southern Bothnain Sea indicates a local Hg-source. The rest of the timeseries show varying concentrations over the study period, and even increasing trends in e.g.cod muscle and blue mussels, but the concentrations are fairly low compared to measuredconcentrations in perch from fresh water and coastal sites. However, in most cases, theseconcentrations are above the newly suggested EU-target level of 20 ng/g wet weight.Lead is generally decreasing over the study period (in time series of sufficient length),supposedly due to the elimination of lead in gasoline. Elevated lead concentrations between2003 and 2007 (e.g. Harufjärden) should be viewed with caution (see above regardingchange in analysis methods).Cadmium concentrations show varying non-linear trends over the monitored period. It isworth noting that despite several measures taken to reduce discharges of cadmium,generally the most recent concentrations are similar to concentrations measured 30 yearsago in the longer time series.The reported nickel concentrations show no consistent decreasing trends. Some series beginwith two elevated values that exert a strong leverage effect on the regression line and maygive a false impression of decreasing trends. Chromium generally shows decreasing trends,possibly explained by a shift in analytical method. The essential trace metals, copper andzinc, show no consistent trends during the monitored period.
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| 7. |
- Bignert, Anders, et al.
(författare)
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Övervakning av metaller och organiska miljögifter i marin biota, 2012
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The environmental toxicants examined in this report can be classified into five groups –heavy metals, chlorinated compounds, brominated flame retardants, polyaromatichydrocarbons and perfluorinated compounds. Each of these contaminants has beenexamined from various sites for up to six different fish species, in blue mussels, and inguillemot eggs, for varying lengths of time. The following summary examines overalltrends, spatial and temporal, for the five groups.Condition and Fat ContentCondition and fat content in different species tended to follow the same pattern at the samesites, with a few exceptions. Most of the fish species generally displayed a decreasing trendin both condition and fat content at most sites examined. Exceptions to this were increasesin fat content and condition factor seen in cod liver at both sites; an increase in conditionfor herring at Ängskärsklubb in spring; and in perch and eelpout, a decrease in fat content atKvädöfjärden (perch) and Väderöarna (eelpout) but no trend in condition for the same site.Heavy MetalsDue to a change in methods for metal analysis (not Hg) in 2004, values between 2003 and2007 should be interpreted with care. From 2009 metals are analyzed at ITM, StockholmUniversity.The longer time series in guillemot egg and spring-caught herring from the southernBothnian Sea and southern Baltic Proper show significant decreases of mercury. Theherring site in the southern Bothnain Sea indicates a local Hg-source. The rest of the timeseries show varying concentrations over the study period, and even increasing trends in e.g.cod muscle and eelpout muscle from Väderöarna, but the concentrations are fairly lowcompared to measured concentrations in perch from fresh water and coastal sites. However,in most cases, these concentrations are above the newly suggested EU-target level of 20ng/g wet weight.Lead is generally decreasing over the study period (in time series of sufficient length),supposedly due to the elimination of lead in gasoline. Elevated lead concentrationsbetween 2003 and 2007 (e.g. Harufjärden) should be viewed with caution (see aboveregarding change in analysis methods).Cadmium concentrations show varying non-linear trends over the monitored period. It isworth noting that despite several measures taken to reduce discharges of cadmium,generally the most recent concentrations are similar to concentrations measured 30 yearsago in the longer time series.The reported nickel concentrations show no consistent decreasing trends. Some series beginwith two elevated values that exert a strong leverage effect on the regression line and maygive a false impression of decreasing trends. Chromium generally shows decreasing trends,possibly explained by a shift in analytical method. The essential trace metals, copper andzinc, show no consistent trends during the monitored period.
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| 8. |
- Dahlstedt, Magnus, et al.
(författare)
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Systemet med fritt skolval måste bytas ut
- 2018
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Ingår i: Svenska Dagbladet.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Ökad segregation och deprofessionalisering av läraryrket är några av effekterna av det fria skolvalet. Nu krävs en grundlig utredning med siktet inställt på att hitta alternativ till nuvarande marknadssystem, skriver ett flertal forskare.
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| 9. |
- Hjort, Martin, et al.
(författare)
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Electronic and Structural Differences between Wurtzite and Zinc Blende InAs Nanowire Surfaces: Experiment and Theory
- 2014
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 8:12, s. 12346-12355
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Tidskriftsartikel (refereegranskat)abstract
- We determine the detailed differences in geometry and band structure between wurtzite (Wz) and zinc blende (Zb) InAs nanowire (NW) surfaces using scanning tunneling microscopy/spectroscopy and photoemission electron microscopy. By establishing unreconstructed and defect-free surface facets for both Wz and Zb, we can reliably measure differences between valence and conduction band edges, the local vacuum levels, and geometric relaxations to the few-millielectronvolt and few-picometer levels, respectively. Surface and bulk density functional theory calculations agree well with the experimental findings and are used to interpret the results, allowing us to obtain information on both surface and bulk electronic structure. We can thus exclude several previously proposed explanations for the observed differences in conductivity of Wz-Zb NW devices. Instead, fundamental structural differences at the atomic scale and nanoscale that we observed between NW surface facets can explain the device behavior.
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| 10. |
- John, Sternbeck, et al.
(författare)
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Organiska miljögifter i fisk från svenska bakgrundsområden
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fisk från nio svenska lokaler, representerande sötvatten, kust och utsjö, har analyserats på PBDE (polybromerade difenyletrar), HBCD, PAH (polycykliska aromatiska kolväten), Klorerade bensener, PCB, ftalater, och klorerade dioxiner och furander i fiskmuskel. Dessutom har pentaklorfenol, triclosan och tetrabrombisfenol A analyserats i fiskgalla från tre av dessa lokaler.
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