| 1. |
- Backman, Anna, et al.
(författare)
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Transport properties of uniaxially oriented aliphatic polyketone
- 2004
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Ingår i: Journal of Polymer Science Part B. - : Wiley. - 0887-6266 .- 1099-0488. ; 42:6, s. 947-955
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Tidskriftsartikel (refereegranskat)abstract
- The oxygen, carbon dioxide, and water-transport properties of a uniaxially oriented aliphatic polyketone were determined. The polyketone was drawn to 5-10 times its original length. The transport properties were related to changes in crystallinity estimated by differential scanning calorimetry and density measurements and by changes in the molecular and crystal orientation assessed by, respectively, infrared and X-ray spectroscopy. The film structures were characterized by confocal scanning laser microscopy and scanning electron microscopy. Stress-strain tests on the drawn specimens enabled the impacts of orientation on the transport and mechanical properties to be compared. A draw-induced increase in crystallinity and molecular orientation yielded permeabilities at a draw ratio of 10 that were 30-40% of the original value, and the percentage decrease was basically independent of the type of gas/vapor molecule. Also, the diffusivities of oxygen and carbon dioxide decreased by an order of magnitude. The fact that the amorphous permeability was peaking at a draw ratio of about 5 was a consequence of a peak in amorphous solubility, which was very high for oxygen and absent for water. It was suggested that the peak in solubility was mainly caused by the destruction of the polymer hydrogen-bond network during drawing and crystal reorientation. The impact of structural reorganization within the polymer and presence of surface valleys seemed to have less impact on the mechanical properties than on the transport properties. This suggested that transport data are more sensitive than mechanical data in probing material defects and changes in molecular packing and morphology.
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| 2. |
- Backman, J.S.K., et al.
(författare)
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Increased Nitrification in Acid Coniferous Forest Soil Due to High Nitrogen Deposition and Liming
- 2003
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 18:6, s. 514-524
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated whether liming stimulates the potential nitrification of acid forest soils in southern Sweden, and whether such stimulation (if present) is more pronounced in areas receiving high nitrogen (N) deposition. A short-term (30 h) soil-slurry incubation technique was used, which reduces the risk of bacterial growth, nitrate immobilization and denitrification during the incubation. The nitrate and nitrite produced were measured after biological conversion to nitrous oxide. The investigation was performed 6-7 yrs after the liming at four coniferous forest sites in the central and western parts of southern Sweden, which receive low and high deposition of N, respectively. Overall, liming had increased pH significantly down to 10 cm soil depth, but at 20 cm depth there was no difference between the limed and non-limed soil. In cases when liming had affected the total N pool and the potential nitrification, this was also limited to the uppermost 10 cm. It seems likely that the effects of liming on the potential nitrification were dependent on N availability, which is in turn influenced by N mineralization, trees' demands for N, and atmospheric N inputs. The strongest stimulatory effect of liming on the potential nitrification was seen on the west coast, indicating that these sites had the highest availability of ammonia for nitrifiers. However, liming also increased nitrification at one of the sites in south-central Sweden, which could have been mediated by increased rates of N mineralization.
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| 3. |
- Backman, J.S.K., et al.
(författare)
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Liming induces growth of a diverse flora of ammonia-oxidising bacteria in acid spruce forest soil as determined by SSCP and DGGE
- 2003
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Ingår i: Soil Biology and Biochemistry. - 0038-0717 .- 1879-3428. ; 35:10, s. 1337-1347
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Tidskriftsartikel (refereegranskat)abstract
- The autotrophic ammonia-oxidising bacterial (AOB) community composition was studied in acid coniferous forest soil profiles at a site in southwestern Sweden 6 years after liming. Liming caused a significant increase in pH in the organic horizons, while the mineral soil was unaffected. The AOB communities were studied by single-strand conformation polymorphism (SSCP) in parallel with denaturing gradient gel electrophoresis (DGGE) analysis of partial 16S rRNA genes amplified by PCR using primers reported to be specific for ß-Proteobacteria AOB, followed by nucleotide sequencing. High genetic diversity of Nitrosospira-like sequences was found in the limed soil profiles, whereas no AOB-like sequences were detected in the control soil at any depth, according to both the SSCP and DGGE analyses. This clearly showed that liming induced growth of a diverse flora of AOB at this forest site. Both Nitrosospira cluster 2 and cluster 4 sequences were present in the limed soil profiles, regardless of soil pH, but we found a higher number of sequences affiliated with cluster 4. The high lime dose seemed to affect the AOB community more than the low dose, and its effects reached deeper into the soil profile. Seven different Nitrosospira-like sequences were found 10 cm under the litter layer in the soil limed with the high dose, but only two in the soil amended with the low lime dose. © 2003 Elsevier Ltd. All rights reserved.
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| 4. |
- Backman, Kaj, et al.
(författare)
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Protocol from the coach crash in Ängelsberg, Sweden, January 2003
- 2004
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Ingår i: International Journal of Disaster Medicine. - : Informa UK Limited. - 1503-1438 .- 1755-4713 .- 1651-3037. ; 2:3, s. 93-104
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Tidskriftsartikel (refereegranskat)abstract
- The crash took place on Friday, 24 January 2003. Due to technical problems, a train was cancelled in Ludvika, a village in central Sweden. A replacement coach was to transport the passengers 115 km to Vsters, via the same route. In darkness, at 4.23 pm, i.e. during working hours, the coach went off the road on a left-hand curve. The driver reduced the speed to 49 km/h before the curve, but lost control of the coach, which skidded off the road, down a high road bank and landed on its right side. The coach's structural damage was mainly located on the right side. Of the 49 occupants, 11 were partially or totally ejected, and 6 were fatally injured. Forty occupants had injuries classified as ISS 1-15, three as ISS 16-30 and six as ISS 41-75. All those in the last group sustained fatal injuries.
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