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| 2. |
- 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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| 3. |
- Backman, A.C., et al.
(författare)
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Differences in wood material responses for radial and tangential direction as measured by dynamic mechanical thermal analysis
- 2001
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 36:15, s. 3777-3783
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Tidskriftsartikel (refereegranskat)abstract
- Wood is a complex cellular structure with different properties in the radial and tangential direction. Many researchers have measured dynamic properties in the longitudinal direction and a few in the radial direction but very little data can be found in the literature on dynamic mechanical properties in the tangential direction. The purpose of the work presented in this paper was to investigate the dynamic mechanical behaviour in the radial and tangential directions of wood (Pinus sylvestris). Testing was done in tension at 1 Hz with a Dynamic Mechanical Thermal Analyser. Properties in radial and tangential direction were different. The radial direction showed a higher elastic modulus and lower loss factor levels at temperatures between -120°C and 80°C. The tangential direction had on average a higher peak temperature than the radial direction for a loss factor peak around -80°C. It is the opposite of synthetic composites where the stiffer direction has a higher peak temperature. A loss factor peak at around 0°C was seen, most significantly in the tangential direction. This peak has scarcely been reported in the literature before. The distance between annual rings did not significantly affect the dynamic behaviour in the tangential direction.
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| 4. |
- Backman, A.C., et al.
(författare)
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Interaction between wood and polyurethane-alkyd lacquer resulting in a decrease in the glass transition temperature
- 2002
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 85:2, s. 595-605
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Tidskriftsartikel (refereegranskat)abstract
- The long-term properties of paint and glue are of great interest to both manufacturers and users of these materials. If a good bond is achieved, the surface between the wood and the paint or glue will be less susceptible to degradation. Thus, the wood and polymer must be compatible and develop some kind of bonding force between them. A high degree of interaction between wood and commercial polyurethane-alkyd lacquer was shown as a decrease by 10°C of the glass transition temperature (Tg) for the lacquer on wood compared to the pure lacquer. The lacquer also demonstrated good adhesion to wood at a microscale. The interaction was investigated with dynamic mechanical thermal analysis and scanning electron microscopy fractography. The reason for the decrease in Tg is probably because of the lacquer having a higher free volume when applied to the wood, most likely due to it being subjected to tensile forces developed during the drying of the lacquer. Results from investigations of wood impregnated with two different acrylates, a polymethylmethacrylate and a more hydrophilic acrylate, support the suggestion that a decrease in Tg will occur if the polymer adheres to wood, but that poor interaction with little or no adhesion will result in no decrease in Tg. This article also presents results of the dynamic mechanical behavior of Scots Pine in the tangential direction
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| 5. |
- Backman, A.C., et al.
(författare)
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Interaction between wood and polyvinyl acetate glue studied with dynamic mechanical analysis and scanning electron microscopy
- 2004
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 91:5, s. 3009-3015
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Tidskriftsartikel (refereegranskat)abstract
- The long-term properties of bonds are those that are of special interest. To achieve good bonds, the wood polymers and the adhering polymers must be compatible. This paper describes studies of the interaction of wood (Pinus sylvestris) with commercial polyvinyl acetate (PVAc) glue, polymethylmethacrylate (PMMA), and a more hydrophilic acrylate. Interaction was studied with a dynamic mechanical thermal analyzer (DMTA) operating in tensile mode in the tangential direction of wood. DMTA results were correlated with scanning electron microscopy (SEM) fractography studies of adhesion between polymers and wood on a cell wall level. The hypothesis put forward is that a good adhesion on the cell wall level results in a decrease in the glass transition temperature (Tg) measured with DMTA. A decrease in Tg for the hydrophilic acrylate was shown when it was impregnated in wood. The decrease of Tg was correlated with good adhesion to wood on the cell wall level. For PVAc and PMMA no decrease in Tg was measured when glued or impregnated in wood. SEM study also showed that the adhesion on a cell wall level was poor. The results show that DMTA can be a useful technique to study adhesion between wood and glue on a molecular level.
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| 6. |
- Backman, A. C., et al.
(författare)
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Volatiles from apple (Malus domestica) eliciting antennal responses in female codling moth Cydia pomonella (L.) (Lepidoptera : Tortricidae): Effect of plant injury and sampling technique
- 2001
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Ingår i: Zeitschrift für Naturforschung C - A Journal of Biosciences. - : Walter de Gruyter GmbH. - 0939-5075 .- 1865-7125. ; 56:04-mar, s. 262-268
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Tidskriftsartikel (refereegranskat)abstract
- The antennal responses of codling moth females, Cydia pomonella, to volatiles from apple branches with green fruits were recorded by electroantennography coupled to gas chromatography. The antennae strongly responded to 4,8-dimethyl-1,3(E),7-nonatriene, linalool, beta -caryophyllene, (E)-beta -farnesene, germacrene D, (Z,E)-alpha -farnesene, (E,E)-alpha -farnesene and methyl salicylate. These compounds were all present in volatile collections on Porapak Q from both living and cut branches. Analysis by the solid phase microextraction technique (SPME) showed that the emission of some electrophysiologically active compounds increased after branches had been cut, especially 4,8-dimethyl-1,3(E),7-nonatriene, linalool and (E,E)-alpha -farnesene. The identification of apple volatiles eliciting antennal responses is the first step towards the identification of compounds mediating host-finding and oviposition in codling moth females.
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| 9. |
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| 10. |
- Backman, L, et al.
(författare)
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Age-related cognitive deficits mediated by changes in the striatal dopamine system
- 2000
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Ingår i: AMERICAN JOURNAL OF PSYCHIATRY. - : AMER PSYCHIATRIC PRESS, INC. - 0002-953X. ; 157:4, s. 635-637
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The study examined the influence of losses in dopaminergic function on age-related cognitive deficits. Method: Eleven healthy subjects (21-68 years of age) completed a set of cognitive tasks used to assess perceptual speed and episodic memory.
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