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  • 201.
    Lifvergren, Thomas
    et al.
    Örebro University, Department of Natural Sciences.
    Nilsson, Harriet
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Remediation of mercury polluted soils - part II: mobilisation of mercury in soil by complexation with chloride and iodideManuscript (preprint) (Other academic)
  • 202.
    Lifvergren, Thomas
    et al.
    Örebro University, Department of Natural Sciences.
    Persson, C.
    Gitye, K.
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Remediation of mercury polluted soils - I: selective extraction of mercury from a soil and speciation by gas chromatography - atomic emission detectionManuscript (preprint) (Other academic)
  • 203.
    Lifvergren, Thomas
    et al.
    Örebro University, Department of Natural Sciences.
    Suèr, Pascal
    Örebro University, Department of Natural Sciences.
    Uggla, Ylva
    Örebro University, Department of Social and Political Sciences.
    Critical remarks concerning the method used in Sweden for risk assessment of contaminated soils (MIFO)Manuscript (preprint) (Other academic)
  • 204.
    Lifvergren, Thomas
    et al.
    Örebro University, Department of Natural Sciences.
    Suèr, Pascal
    Örebro University, Department of Natural Sciences.
    Wievegg, U.
    Microwave-assisted digestion of mercury polluted soilsManuscript (preprint) (Other academic)
  • 205. Lind, Bo
    et al.
    Bäckström, Mattias
    Örebro University, Department of Natural Sciences.
    Geisler, Erika
    First flush effect of metals and anions in stormwater runoff from roads in mid-Sweden2001In: Urban transport VII: urban transport and the environment for the 21st century / [ed] L.J. Sucharov, C.A. Brebbia, Southampton: WIT Press , 2001, p. 497-508Conference paper (Other academic)
  • 206.
    Lotfollahi, Ramin
    Örebro University, Department of Natural Sciences.
    Electronic structure of surfaces2006Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For an idealized one-dimensional crystal it is possible to have energy levels whose wave functions are localized at the surface. These states are called surface states. There is one surface state for each energy gap between the ordinary allowed bands of energies. These electron states are called Tamm states. This Tamm state has an energy that lies almost at the middle of the energy gap and is mainly localized at the surface atomic layer. The image potential states are generated by a potential well formed by the Coulomb-like image potential barrier. These image states that are also called Shockley states are localized in a slowly decaying tail in the vacuum.

    I also studied the lateral (in-plane) motion of electrons confined to terraces between steps on a vicinal Cu (111) surface. The local density of states showed a number of peaks at energies where electrons can occupy new quantum-well states on a step. I also tested the influence of the electron lifetime on the local density of states.

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  • 207.
    Löthgren, Carl-Johan
    Örebro University, Department of Natural Sciences.
    Mercury and dioxins in a MercOx-scrubber2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The removal of mercury and the absorption of dioxins in an acid wet scrubber have been studied in industrial scale. Hydrogen peroxide is added as an oxidizing agent to the scrubber liquid with the purpose to remove SO2 and enhance the removal of mercury. The scrubber is operating as the final flue gas cleaning stage at the SAKAB plant, a hazardous waste incinerator in Sweden.

    Mercury speciation was measured in flue gases upstream and downstream of the scrubber with three different techniques: Impingers, solid phase absorbents and a continuous emission monitor. During the flue gas sampling periods also the scrubber liquid was sampled. It was found that mercury entering the scrubber is efficiently oxidized at normal operating conditions. An increased fraction of elemental gaseous mercury was found in flue gases after the scrubber at redox potentials below 700 mV and pH below 1. The mercury emissions were more dependent on the scrubber liquid composition than on the inlet concentrations.

    Equilibrium calculations of the mercury speciation in the scrubber liquid and flue gases after the scrubber showed that mercury is normally emitted as HgBr2 or HgCl2. Elemental bromine and chlorine are formed in the scrubber. Both species probably take part in the mercury oxidation process.

    Results from 18 months of dioxin sampling, using a continuous long term sampling device (the AMESA system) were evaluated by multivariate data analyses. It was shown that the elevated emissions observed were caused by a memory effect in the scrubber due to high start-up concentrations. The memory effect was modelled in a diffusion model where the dioxins were considered to be physically absorbed in and desorbed from the polypropylene fillings of the scrubber. From the diffusion model, the diffusivities for tetra to hexa chlorinated dioxins in polypropylene were calculated. The diffusivity of tetra chlorinated dioxins was calculated to be 10-14 m2/s. The diffusivity decreases with increasing chlorination. For hexa chlorinated dioxins it was calculated to be 10-16 m2/s.

    Brominated dioxins were measured before and after a fabric filter. The fraction of brominated dioxins increased after the filter. Di brominated furans were the most abundant homologue.

    List of papers
    1. Mercury speciation in flue gases after an oxidative acid wet scrubber
    Open this publication in new window or tab >>Mercury speciation in flue gases after an oxidative acid wet scrubber
    Show others...
    2007 (English)In: Chemical Engineering & Technology, ISSN 0930-7516, E-ISSN 1521-4125, Vol. 30, no 1, p. 131-138Article in journal (Refereed) Published
    Abstract [en]

    Flue gases from a hazardous waste incinerator have been sampled in three campaigns, before and after, an oxidative acid wet scrubber working with the MercOx-process. A continuous emission monitor for mercury speciation was used before the scrubber in the first campaign. In all campaigns, impingers with KCl and KMnO4 were used. A solid adsorption method was used in the last campaign. The mercury leaving the scrubber is oxidized at > 90 % efficiency (independent of the inlet speciation). A substantial decrease in the redox potential of the scrubber liquid caused an increased fraction of elemental gaseous mercury to be present in the clean gas. The measurements also show that the scrubber has the ability to readily absorb mercury peaks. During one extreme peak of 3,600 μg/m3 (dry gas) in the raw gas, the removal efficiency was above 99.9 %.

    National Category
    Engineering and Technology Chemical Engineering
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3203 (URN)10.1002/ceat.200600172 (DOI)
    Available from: 2006-12-29 Created: 2006-12-29 Last updated: 2017-12-14Bibliographically approved
    2. Equilibrium calculations of mercury in a MercOx scrubber
    Open this publication in new window or tab >>Equilibrium calculations of mercury in a MercOx scrubber
    (English)Manuscript (Other academic)
    National Category
    Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3204 (URN)
    Available from: 2006-12-29 Created: 2006-12-29 Last updated: 2017-10-18Bibliographically approved
    3. Dioxin emissions after installation of a polishing wet scrubber in a hazardous waste incineration facility
    Open this publication in new window or tab >>Dioxin emissions after installation of a polishing wet scrubber in a hazardous waste incineration facility
    2005 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 61, no 3, p. 405-412Article in journal (Refereed) Published
    Abstract [en]

    Dioxin levels measured after wet scrubbing systems have been found to be higher than levels measured before the scrubber. It is believed that there is an adsorption of PCDD/Fs on plastic materials in the scrubber. The PCDD/F levels after a polishing wet scrubber were followed continuously for 18 months using long-time sampling equipment at a hazardous waste incineration facility in Sweden. Each sampling period lasted two weeks. It was found that the levels during and shortly after start-up periods were elevated. The decline was very slowly, which supports a memory effect in the scrubber. Further, a multivariate model showed that the relation between different homologues changed over time, which is in agreement with a desorption model, taking into account the vapour pressures for different congeners.

    National Category
    Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3205 (URN)10.1016/j.chemosphere.2005.02.015 (DOI)
    Available from: 2006-12-29 Created: 2006-12-29 Last updated: 2017-12-14Bibliographically approved
    4. Numerical modelling of the memory effect in wet scrubbers
    Open this publication in new window or tab >>Numerical modelling of the memory effect in wet scrubbers
    2008 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 73, no 1, p. S101-S105Article in journal (Refereed) Published
    Abstract [en]

    Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) can be absorbed in and desorbed from polypropylene (PP) tower packings in wet scrubbers utilized in waste incineration lines. This behaviour, also known as the memory effect, has been modelled using a gas phase – PP surface equilibrium and a numerical solid phase diffusion model describing the transport of PCDD/Fs inside the PP. The diffusivities and gas – PP partition coefficients of TCDD/F to HxCDD/Fs in PP have been estimated using the numerical model. Two incineration lines were modelled. In the first line, the absorption and desorption in PP test rods was followed before and after installation of a fabric filter that was placed before a wet scrubber. In the second incineration line, the accumulation of PCDD/Fs in a wet scrubber during start up periods and the subsequent decline during the following three months was modelled and compared to continuous two-week gas measurements after the scrubber. The obtained diffusivities in PP range from 10−13 m2/s for TCDD to 10−16 m2/s for HxCDD. Lower chlorinated homologues with a distinctive change in concentrations during the desorption period (e.g. TCDF) are easier to model, and show the best agreement between the two incineration lines.

    National Category
    Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3206 (URN)10.1016/j.chemosphere.2007.06.095 (DOI)
    Note
    Supplement 1. Halogenated Persistent Organic Pollutants Dioxin 2005 - Selected Papers from the 25th International Symposium on Halogenated Environmental Organic Pollutants and POPs held in Toronto, Canada, August 2005Available from: 2006-12-29 Created: 2006-12-29 Last updated: 2017-12-14Bibliographically approved
    5. Comparison of PBDD/Fs and PCDD/Fs in flue gases and fly ash from a MSW incinerator
    Open this publication in new window or tab >>Comparison of PBDD/Fs and PCDD/Fs in flue gases and fly ash from a MSW incinerator
    2006 (English)In: Organohalogen Compounds, ISSN 1026-4892, Vol. 68, p. 1800-1803Article in journal (Refereed) Published
    Place, publisher, year, edition, pages
    Vienna: Federal Environmental Agency, 2006
    National Category
    Environmental Sciences
    Research subject
    Environmental Chemistry
    Identifiers
    urn:nbn:se:oru:diva-3207 (URN)
    Available from: 2006-12-29 Created: 2006-12-29 Last updated: 2017-10-18Bibliographically approved
  • 208.
    Löthgren, Carl-Johan
    et al.
    Örebro University, Department of Natural Sciences.
    Andersson, Sven
    Numerical modelling of the memory effect in wet scrubbers2008In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 73, no 1, p. S101-S105Article in journal (Refereed)
    Abstract [en]

    Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) can be absorbed in and desorbed from polypropylene (PP) tower packings in wet scrubbers utilized in waste incineration lines. This behaviour, also known as the memory effect, has been modelled using a gas phase – PP surface equilibrium and a numerical solid phase diffusion model describing the transport of PCDD/Fs inside the PP. The diffusivities and gas – PP partition coefficients of TCDD/F to HxCDD/Fs in PP have been estimated using the numerical model. Two incineration lines were modelled. In the first line, the absorption and desorption in PP test rods was followed before and after installation of a fabric filter that was placed before a wet scrubber. In the second incineration line, the accumulation of PCDD/Fs in a wet scrubber during start up periods and the subsequent decline during the following three months was modelled and compared to continuous two-week gas measurements after the scrubber. The obtained diffusivities in PP range from 10−13 m2/s for TCDD to 10−16 m2/s for HxCDD. Lower chlorinated homologues with a distinctive change in concentrations during the desorption period (e.g. TCDF) are easier to model, and show the best agreement between the two incineration lines.

  • 209.
    Löthgren, Carl-Johan
    et al.
    Örebro University, Department of Natural Sciences.
    Andersson, Sven
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Equilibrium calculations of mercury in a MercOx scrubberManuscript (Other academic)
  • 210.
    Löthgren, Carl-Johan
    et al.
    Örebro University, Department of Natural Sciences.
    Hagberg, Jessika
    Örebro University, Department of Natural Sciences.
    van Bavel, Bert
    Örebro University, Department of Natural Sciences.
    Lindström, Gunilla
    Örebro University, Department of Natural Sciences.
    Comparison of PBDD/Fs and PCDD/Fs in flue gases and fly ash from a MSW incinerator2006In: Organohalogen Compounds, ISSN 1026-4892, Vol. 68, p. 1800-1803Article in journal (Refereed)
  • 211.
    Löthgren, Carl-Johan
    et al.
    Örebro University, Department of Natural Sciences.
    Takaoka, Masaki
    Andersson, Sven
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Korell, Jens
    Mercury speciation in flue gases after an oxidative acid wet scrubber2007In: Chemical Engineering & Technology, ISSN 0930-7516, E-ISSN 1521-4125, Vol. 30, no 1, p. 131-138Article in journal (Refereed)
    Abstract [en]

    Flue gases from a hazardous waste incinerator have been sampled in three campaigns, before and after, an oxidative acid wet scrubber working with the MercOx-process. A continuous emission monitor for mercury speciation was used before the scrubber in the first campaign. In all campaigns, impingers with KCl and KMnO4 were used. A solid adsorption method was used in the last campaign. The mercury leaving the scrubber is oxidized at > 90 % efficiency (independent of the inlet speciation). A substantial decrease in the redox potential of the scrubber liquid caused an increased fraction of elemental gaseous mercury to be present in the clean gas. The measurements also show that the scrubber has the ability to readily absorb mercury peaks. During one extreme peak of 3,600 μg/m3 (dry gas) in the raw gas, the removal efficiency was above 99.9 %.

  • 212.
    Löthgren, Carl-Johan
    et al.
    Örebro University, Department of Natural Sciences.
    van Bavel, Bert
    Örebro University, Department of Natural Sciences.
    Dioxin emissions after installation of a polishing wet scrubber in a hazardous waste incineration facility2005In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 61, no 3, p. 405-412Article in journal (Refereed)
    Abstract [en]

    Dioxin levels measured after wet scrubbing systems have been found to be higher than levels measured before the scrubber. It is believed that there is an adsorption of PCDD/Fs on plastic materials in the scrubber. The PCDD/F levels after a polishing wet scrubber were followed continuously for 18 months using long-time sampling equipment at a hazardous waste incineration facility in Sweden. Each sampling period lasted two weeks. It was found that the levels during and shortly after start-up periods were elevated. The decline was very slowly, which supports a memory effect in the scrubber. Further, a multivariate model showed that the relation between different homologues changed over time, which is in agreement with a desorption model, taking into account the vapour pressures for different congeners.

  • 213.
    Malmgren, Jan C.
    Örebro University, Department of Natural Sciences.
    Allometry for sexual size dimorphism in newts of the genus Triturus (Caudata: Salamandridae)Manuscript (preprint) (Other academic)
  • 214.
    Malmgren, Jan C.
    Örebro University, Department of Natural Sciences.
    Escape from the developmental arrest: the peculiar case of the marbled newt and the crested newt superspeciesManuscript (preprint) (Other academic)
  • 215.
    Malmgren, Jan C.
    Örebro University, Department of Natural Sciences.
    Evolutionary ecology of newts2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Sexual dimorphism, predator avoidance and migratory behaviour are adaptive traits that show variation at the population and species level. Such features respond to the environment in the broad sense, that is, when both abiotic and biotic components are included. Newts of the genus Triturus have several unique features and therefore make interesting model organisms.

    I use multivariate methods to test predictions about the evolution of sex differences in morphological traits. There was no evidence for dimorphism due to diverging feeding niche specialisation between the sexes in great crested and smooth newts (Triturus cristatus and T. vulgaris, respectively). The sexes, on the other hand, diverged in traits related to female fecundity and male reproductive success. Within the genus Triturus, there was no overall allometry for sexual size dimorphism (SSD), but subgenus Triturus, a lineage comprised by medium- to large-bodied species, were significantly allometric, and SSD decreased with increasing body size for male-biased taxa and increased with size for female-biased taxa. Species in the marmoratus-cristatus species group were almost perfectly isometric, but female-biased. With respect to an ancestral state, I suggest that differences in mating system have caused medium- and small-bodied species (subgenus Palaeotriton) to decrease SSD with smaller body size, whereas subgenus Triturus have evolved larger body size with a reversal from male- to female-biased SSD. Several peculiar traits are common to the latter group. I argue, and present a conceptual model, that the reversal is an adaptation to genetic constraints posed by a balanced lethal system (the developmental arrest syndrome). Several life history traits, as well as morphological and reproductive traits, may be interpreted as evidence for the scenario. Predictions from the model are presented and future research to test the validity of the model is encouraged.

    Newts are threatened by the introduction of fish and predictions from a predator-prey model on the evolution of predator avoidance behaviour, are tested. The results suggest that the great crested newt may be able to detect chemical cues from the ninespined stickleback, Pungitius pungitius, and adjust its behaviour accordingly. The response could be a predator avoidance response that enables adults to increase reproductive success by eliminating predation risk. I also studied migration behaviour in response to surrounding landscape elements after breeding and metamorphosis in great crested and smooth newts. Fragmentation effects reduce the chance for newts to disperse to suitable habitat patches in the landscape. I demonstrate that newts appear to orientate towards forest non-randomly, regardless of age-class or species, and their responses may be used to predict where critical elements for population persistence are located, in relation to a breeding pond. Overall, the results from my studies suggest that the great crested newt may be more prone to local extinction than previously believed, much due to genetic constraints and possible habitat specialisation. I use the results to present avenues for future research and discuss implications from my studies for management and conservation of newts and newt-friendly landscapes.

    List of papers
    1. Sexual size and shape dimorphism in two species of newts, Triturus cristatus and T-vulgaris (Caudata: Salamandridae):  
    Open this publication in new window or tab >>Sexual size and shape dimorphism in two species of newts, Triturus cristatus and T-vulgaris (Caudata: Salamandridae):  
    1999 (English)In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 249, no 2, p. 127-136Article in journal (Refereed) Published
    Abstract [en]

    Morphometric data from Fennoscandian populations of the crested newt Triturus cristatus and the smooth newt Triturus vulgaris were analysed for the presence of sexual size and shape dimorphism. The data sets included nine body-related and nine head-related measurements and were examined with univariate, bivariate and multivariate methods. Sexual dimorphism was demonstrated in both species. The separation of specimens was highly related to sex. Although the expression of sexual dimorphism differed between the two species, some patterns were shared. These are discussed in terms of evolution of intersexual dimorphism according to models of ecology, fecundity and sexual selection. In multivariate analyses, sexual dimorphism was restricted to body-related variables such as standard length and distance of extremities (with high values for females), contrasting against cloaca and limb-related characters (with high values for males). In both species, the 'distance of extremities' measure (i.e. trunk length) was one of the strongest sexually dimorphic traits. No evidence of sexual dimorphism in head morphology was found. The results are interpreted as primarily concordant with theories on fecundity selection. For example, it has been suggested that females with larger trunk volumes increase their reproductive capacity. The fact that males had longer extremities, in relation to other characters measured, could be attributed to sexual selection. Long limbs in male newts may be beneficial for courtship performance. Since head-related characters did not show any patterns of sexual dimorphism, no evidence was found to suggest that male and female crested and smooth newts have adapted to different feeding strategies.

    Keywords
    Triturus cristatus, Triturus vulgaris, sexual dimorphism, sexual selection, fecundity
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-15972 (URN)10.1111/j.1469-7998.1999.tb00750.x (DOI)000083118600001 ()
    Available from: 2011-06-16 Created: 2011-06-16 Last updated: 2017-12-11Bibliographically approved
    2. Allometry for sexual size dimorphism in newts of the genus Triturus (Caudata: Salamandridae)
    Open this publication in new window or tab >>Allometry for sexual size dimorphism in newts of the genus Triturus (Caudata: Salamandridae)
    (English)Manuscript (preprint) (Other academic)
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-15973 (URN)
    Available from: 2011-06-16 Created: 2011-06-16 Last updated: 2017-10-17Bibliographically approved
    3. Escape from the developmental arrest: the peculiar case of the marbled newt and the crested newt superspecies
    Open this publication in new window or tab >>Escape from the developmental arrest: the peculiar case of the marbled newt and the crested newt superspecies
    (English)Manuscript (preprint) (Other academic)
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-15974 (URN)
    Available from: 2011-06-16 Created: 2011-06-16 Last updated: 2017-10-17Bibliographically approved
    4. Predator avoidance response by adult newts to fish cues
    Open this publication in new window or tab >>Predator avoidance response by adult newts to fish cues
    (English)Manuscript (preprint) (Other academic)
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-15975 (URN)
    Available from: 2011-06-16 Created: 2011-06-16 Last updated: 2017-10-17Bibliographically approved
    5. How does a newt find its way from a pond?: Migration patterns after breeding and metamorphosis in great crested newts (Triturus cristatus) and smooth newts (T-vulgaris)
    Open this publication in new window or tab >>How does a newt find its way from a pond?: Migration patterns after breeding and metamorphosis in great crested newts (Triturus cristatus) and smooth newts (T-vulgaris)
    2002 (English)In: Herpetological Journal, ISSN 0268-0130, Vol. 12, no 1, p. 29-35Article in journal (Refereed) Published
    Abstract [en]

    Migration patterns across adrift fence with pitfall traps were studied between 1997 and 1999 at a breeding pond with populations of great crested newts, Triturus cristatus, and smooth newts, T. vulgaris, at a study site in south-central Sweden. Metamorphs and older newts emigrated from the pond non-randomly and seemed to avoid exiting where open fields adjoined, but were oriented towards a patch of forest immediately to the east of the pond. Movement patterns changed slightly over the years, but metamorphs were more dispersed and less concentrated than older newts, and did not choose directions identical to those of older newts. Older great crested and smooth newts showed similar directional orientation. Great crested newt metamorphs dispersed towards both edges of the forest patch, and possible explanations for this are discussed. The results suggest that orientation in relation to cues from the surroundings of a breeding pond may be used by newts to make migratory decisions.

    Keywords
    amphibia, behaviour, conservation, dispersion, circular statistics
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-15971 (URN)000175926000004 ()
    Available from: 2011-06-16 Created: 2011-06-16 Last updated: 2017-12-11Bibliographically approved
  • 216.
    Malmgren, Jan C.
    Örebro University, Department of Natural Sciences.
    How does a newt find its way from a pond?: Migration patterns after breeding and metamorphosis in great crested newts (Triturus cristatus) and smooth newts (T-vulgaris)2002In: Herpetological Journal, ISSN 0268-0130, Vol. 12, no 1, p. 29-35Article in journal (Refereed)
    Abstract [en]

    Migration patterns across adrift fence with pitfall traps were studied between 1997 and 1999 at a breeding pond with populations of great crested newts, Triturus cristatus, and smooth newts, T. vulgaris, at a study site in south-central Sweden. Metamorphs and older newts emigrated from the pond non-randomly and seemed to avoid exiting where open fields adjoined, but were oriented towards a patch of forest immediately to the east of the pond. Movement patterns changed slightly over the years, but metamorphs were more dispersed and less concentrated than older newts, and did not choose directions identical to those of older newts. Older great crested and smooth newts showed similar directional orientation. Great crested newt metamorphs dispersed towards both edges of the forest patch, and possible explanations for this are discussed. The results suggest that orientation in relation to cues from the surroundings of a breeding pond may be used by newts to make migratory decisions.

  • 217.
    Malmgren, Jan C.
    et al.
    Örebro University, Department of Natural Sciences.
    Bülow, Per
    Predator avoidance response by adult newts to fish cuesManuscript (preprint) (Other academic)
  • 218.
    Malmgren, Jan C.
    et al.
    Örebro University, Department of Natural Sciences.
    Enghag, M.
    Örebro University, Department of Natural Sciences.
    Female preference for male dorsal crests in great crested newts (Triturus cristatus)2008In: Ethology Ecology & Evolution (Testo stampato), ISSN 0394-9370, E-ISSN 1828-7131, Vol. 20, no 1, p. 71-80Article in journal (Refereed)
    Abstract [en]

    Studies of mate choice in great crested newts have established a difficulty in separating the visual constituent of the male's dorsal crest from its importance to cutaneous respiration and the conveying of pheromones during courtship. We used image manipulation to test if size differences in the dorsal crest alone can be evaluated visually by female newts, controlling for other differences between males. Females responded well to the experimental design and did not remain in front of simulated male 'models' independently of differences in dorsal crest height. Instead, they spent more than twice as much time in front of the manipulated high-crested male, than in front of the non-manipulated low-crested male, which was significant also after controlling for zone area. However, the design failed to determine if females remained true to their first choice, probably due to a combination of low sample size and male 'models' remaining unnaturally indifferent to female interest.

  • 219.
    Malmgren, Jan C.
    et al.
    Örebro University, Department of Natural Sciences.
    Thollesson, Mikael
    Sexual size and shape dimorphism in two species of newts, Triturus cristatus and T-vulgaris (Caudata: Salamandridae):  1999In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 249, no 2, p. 127-136Article in journal (Refereed)
    Abstract [en]

    Morphometric data from Fennoscandian populations of the crested newt Triturus cristatus and the smooth newt Triturus vulgaris were analysed for the presence of sexual size and shape dimorphism. The data sets included nine body-related and nine head-related measurements and were examined with univariate, bivariate and multivariate methods. Sexual dimorphism was demonstrated in both species. The separation of specimens was highly related to sex. Although the expression of sexual dimorphism differed between the two species, some patterns were shared. These are discussed in terms of evolution of intersexual dimorphism according to models of ecology, fecundity and sexual selection. In multivariate analyses, sexual dimorphism was restricted to body-related variables such as standard length and distance of extremities (with high values for females), contrasting against cloaca and limb-related characters (with high values for males). In both species, the 'distance of extremities' measure (i.e. trunk length) was one of the strongest sexually dimorphic traits. No evidence of sexual dimorphism in head morphology was found. The results are interpreted as primarily concordant with theories on fecundity selection. For example, it has been suggested that females with larger trunk volumes increase their reproductive capacity. The fact that males had longer extremities, in relation to other characters measured, could be attributed to sexual selection. Long limbs in male newts may be beneficial for courtship performance. Since head-related characters did not show any patterns of sexual dimorphism, no evidence was found to suggest that male and female crested and smooth newts have adapted to different feeding strategies.

  • 220.
    Mannerling, Ann-Christine
    et al.
    Örebro University, Department of Natural Sciences.
    Hansson-Mild, Kjell
    Örebro University, Department of Natural Sciences.
    Mattsson, Mats-Olof
    Örebro University, Department of Natural Sciences.
    Extremely low-frequency magnetic field exposure and protection against UV-induced death in chicken embryos2007In: Electromagnetic Biology and Medicine, ISSN 1536-8378, E-ISSN 1536-8386, Vol. 26, no 2, p. 73-81Article in journal (Refereed)
    Abstract [en]

    We report on a study where 4-day old chicken embryos from different flocks were pre-treated with 50 Hz magnetic fields (MF) prior to a 60-min UV-C exposure (1.7 mW/cm(2)) to investigate the possible protective effect of MF exposure on UV-induced embryo death. Different flux densities (0.010, 0.025, 0.050, 0.10, and 0.20 mT), field directions (vertical and horizontal), as well as MF exposure times (10, 20, and 60min) were employed. We did not find any significant effects by MF exposure, irrespective of exposure time, flux density, or field direction on the survival of embryos. Neither could we find any flock dependency on sensitivity to MF exposure.

  • 221.
    Martin, Jonathan
    et al.
    University of Toronto.
    Kannan, Kurunthachalam
    State university of New York at Albany.
    Berger, Urs
    NILU.
    de Voogt, Pim
    University of Amsterdam.
    Field, Jennifer
    Oregon State University.
    Franklin, James
    Solvay.
    Giesy, John
    Michigan State University.
    Harner, Tom
    Environment Canada.
    Muir, Derek
    Environment Canada.
    Scott, Brian
    Environment Canada.
    Kaiser, Mary
    DuPont.
    Järnberg, Ulf
    Stockholms universitet.
    Jones, Kevin
    Lancaster University.
    Mabury, Scott
    University of Toronto.
    Schroeder, Horst
    RWTH Aachen.
    Simcik, Matt
    University of Minnesota.
    Sottani, Christina
    Salvatore Maugeri Foundation.
    van Bavel, Bert
    Örebro University, Department of Natural Sciences.
    Kärrman, Anna
    Örebro University, Department of Natural Sciences.
    Lindström, Gunilla
    Örebro University, Department of Natural Sciences.
    van Leeuwen, Stefan
    Netherlands Institute for Fisheries research.
    Analytical challenges hamper perfluoroalkyl research2004In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 38, no 13, p. 248A-255AArticle in journal (Refereed)
  • 222.
    Mattsson, Johanna
    Örebro University, Department of Natural Sciences.
    Purification of the recombinant SAD-C protein from Pisum sativum (pea)2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    SAD-C, a gene belonging to the small short-chain alcohol dehydrogenase-like protein (SAD) gene family, is up-regulated in Pisum sativum (pea) when the plant is exposed to UV-B (280-320 nm) radiation. SAD-C has a molecular weight of about 28 kDa and adopts a tetrameric structure. The aim of this work was to purify the protein SAD-C from Pisum sativum when overexpressed in E. coli strain BL21 StarTM (DE3) One Shot®.

    The purification was facilitated by the presence of a His-tag consisting of six histidine residues at the C-terminal end of the protein. The purification trials of SAD-C were faced with problems since the sample fractions contained several other proteins as well. Several purification steps seem to be necessary for future trials. A crystallization trial was still set up and crystals were formed, but the crystals formed were probably not of SAD-C.

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  • 223.
    Matxain, Jon M.
    et al.
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Formoso, Elena
    Piris, Mario
    Ugalde, Jesus M.
    Endohedral (X@ZniSi)i=4-160,± Nanoclusters, X = Li, Na, K, Cl, Br2007In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, no 9, p. 3560-3565Article in journal (Refereed)
    Abstract [en]

    Endohedral (X@ZniSi)q structures have been characterized, with X being alkali metals such as Li, Na, and K or halogens such as Cl and Br, 4 > i > 16, and q = -1, 0, 1. In these structures, the atoms are trapped inside previously characterized spheroid hollow structures with positively charged Zn atoms and negatively charged S atoms. Moreover, although the radii of all atoms are similar, Zn atoms are located more inside the structure. The alkali metals are found to be trapped inside a larger number of spheroid structures than the halogens. The parameters determining the stability of the endohedral structures are the charge and size of the trapped atom, along with the sphericity of the cluster.

  • 224.
    Matxain, Jon M
    et al.
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A
    Örebro University, Department of Natural Sciences.
    Mercero, Jose M
    Lopez, Xabier
    Piris, Mario
    Ugalde, Jesus M
    Poater, Jordi
    Matito, E
    Solá, Miguel
    New solids based on B12N12 fullerenes2007In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, no 36, p. 13354-60Article in journal (Refereed)
    Abstract [en]

    In recent years, BN fullerenes have been synthesized experimentally. As their carbon counterparts, these BN fullerenes could be assembled in molecular solids, but this possibility has been studied little in the literature. In this work, we focus on the smallest synthesized BN fullerene, B12N12, which is built by squares and hexagons. First, the interaction between two of these fullerenes has been analyzed, using the hybrid B3LYP and MPW1PW91 density functional methods. Two different interactions have been studied in the dimer, a square facing a square (S−S) and a hexagon facing a hexagon (H−H). In both cases, a B is facing a N. The most stable dimer was found to be S−S facing, with covalent interactions between the monomers, but other dimers with weak interactions have been found as well, which opens possibilities of new systems, as in the case of fullerene dimers and solids. The solids resulting from the infinite repetition of the characterized dimers were optimized, finding two different solids, with covalent and weak interactions between monomers, respectively. The solid with covalent interactions is a nanoporous material that is more stable by around 12 eV. Because of the nanoporous character of this solid, it could be used for heterogeneous catalysis, molecular transport, and so forth. The SIESTA code with the GGA-PBE density functional method has been used for the solid-state calculations.

  • 225.
    Matxain, Jon M.
    et al.
    Örebro University, Department of Natural Sciences.
    Ristilä, Mikael
    Örebro University, Department of Natural Sciences.
    Strid, Åke
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Theoretical study of the antioxidant properties of pyridoxine2006In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 110, no 48, p. 13068-13072Article in journal (Refereed)
    Abstract [en]

    Molecules acting as antioxidants capable of scavenging reactive oxygen species (ROS) are of utmost importance in the living cell. The antioxidative properties of pyridoxine (vitamin B6) have recently been discovered. In this study, we have analyzed the reactivity of pyridoxine toward the ROS .OH, .OOH, and .O2- at the density functional theory level (functionals B3LYP and MPW1B95). Two reaction types have been studied as follows: addition to the aromatic ring atoms and hydrogen/proton abstraction. Our results show that .OH is the most reactive species, while .OOH displays low reactivity and .O2- does not react at all with pyridoxine. The most exergonic reactions are those where .H is removed from the CH2OH groups or the ring-bound OH group and range from -33 to -39 kcal/mol. The most exergonic addition reactions occur by attacking the carbon atoms bonded to nitrogen but with an energy gain of only 6 kcal/mol.

  • 226.
    Matxain, Jon M
    et al.
    Örebro University, Department of Natural Sciences.
    Ristilä, Mikael
    Örebro University, Department of Natural Sciences.
    Strid, Åke
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A
    Örebro University, Department of Natural Sciences.
    Theoretical study of the reaction of vitamin B6 with 1O22007In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, no 16, p. 4636-42Article in journal (Refereed)
    Abstract [en]

    Singlet oxygen is known to cause oxidative stress in cells, leading to severe damage (e.g., lipid peroxidation, membrane degradation, mutagenic alterations to DNA, protein misfunctionality). Recently, pyridoxine has been discovered to be capable of quenching singlet oxygen, however, the mechanism of this reaction remains essentially unknown. In this work, we have investigated four sets of reactions: 1) 1,3-addition to a double bond connected to a hydrogen-carrying group,resulting in the formation of allylic hydroperoxides; 2) [p2+p2] 1,2-cycloaddition to an isolated double bond, resulting in the formation of 1,2-peroxides; 3) 1,4-cycloaddition to a system containing at least two conjugated double bonds, resulting in the formation of the so-called 1,4-peroxides;4) 1,4-addition to phenols and naphthols with the formation of hydroperoxide ketones. Thermodynamically, reaction 4 and the 6(9), 3(8), and 5(8) cases of reaction 1 are the most exergonic ones, with energies ranging from 16 to 18 kcalmol 1. Furthermore, reaction 4 shows the lowest barrier through the reaction path, and is predicted to be the preferred mechanism

    for the pyridoxine + singlet-oxygen reaction, which is in agreement with previous experimental results.

  • 227. Mayer, Gregory D.
    et al.
    Leach, Allan
    Kling, Peter
    Olsson, Per-Erik
    Örebro University, Department of Natural Sciences.
    Hogstrand, Christer
    Activation of the rainbow trout metallothionein-A promoter by silver and zinc2003In: Comparative Biochemistry and Physiology - Part B: Biochemistry & Molecular Biology, ISSN 1096-4959, E-ISSN 1879-1107, Vol. 134, no 1, p. 181-188Article in journal (Refereed)
    Abstract [en]

    In fish, the synthesis of metallothionein (MT) is increased by a number of heavy metals. The rainbow trout MT-A gene promoter region contains six known metal responsive elements (MREs), that mediate promoter activation by metals. In the present study, two fish cell lines differing in their ability to produce MT, RTG-2 (produce MT protein) and CHSE-214 (produce no detectable MT protein), were used to help elucidate the roles of Zn, Ag and MT in the activation of the MT promoter. The hypothesis tested was that Ag activates the MT-A promoter indirectly by displacing Zn from pre-existing Zn-MT and that this liberated Zn subsequently induces MT synthesis. Both cell lines were transfected with a luciferase reporter gene construct containing the rainbow trout MT-A promoter, exposed to various concentrations of Zn or Ag, and assayed for luciferase activity. CHSE-214 cells showed five times greater production of luciferase than RTG-2 cells when exposed to identical concentrations of Ag. Thus, Ag can likely induce MT transcription without displacing Zn from pre-existing Zn-MT. Furthermore, Ag activated the MT promoter at concentrations 100-fold lower than those required for Zn to initiate transcription, suggesting that zinc displaced from other sites by such low concentrations of Ag would not be sufficient to initiate MT transcription. This interpretation was further supported by radiotracer studies indicating that Ag did not cause a redistribution of 65Zn within either of the two cell types. These combined results indicate that Ag may be a direct inducer of MT.

  • 228.
    Modig, Carina
    et al.
    Örebro University, Department of Natural Sciences.
    Modesto, Teresa
    Canario, Adelino
    Cerdà, Joan
    von Hofsten, Jonas
    Olsson, Per-Erik
    Örebro University, Department of Natural Sciences.
    Molecular characterization and expression pattern of zona pellucida proteins in gilthead seabream (Sparus aurata)2006In: Biology of Reproduction, ISSN 0006-3363, E-ISSN 1529-7268, Vol. 75, no 5, p. 717-725Article in journal (Refereed)
    Abstract [en]

    The developing oocyte is surrounded by an acellular envelope that is composed of 2-4 isoforms of zona pellucida (ZP) proteins. The ZP proteins comprise the ZP1, ZP2, ZP3, and ZPX isoforms. While ZP1 (ZPB) and ZP3 (ZPC) are present in all species, ZP2 (ZPA) is not found in teleost fish and ZPX is not found in mammals. In the present study, we identify and characterize the ZP1, ZP3 and ZPX isoforms of gilthead seabream. Furthermore, by analyzing the conserved domains, which include the external hydrophobic patch and the internal hydrophobic patch, we show that ZP2 and ZPX are closely related isoforms. ZP proteins are synthesized in either the liver or ovary of most teleosts. Only in rainbow trout has it been shown that zp3 has dual transcription sites. In gilthead seabream, all four mRNA isoforms are transcribed in both the liver and ovary, with zp1a, zp1b, and zp3 being highly expressed in the liver, and zpx being primarily expressed in the ovary. However, determination of the ZP proteins in plasma showed high levels of ZP1b, ZP3, and ZPX, with low or non-detectable levels of ZP1a. In similarity to other teleost ZPs, the hepatic transcription of all four ZP isoforms is under estrogenic control. Previously, we have shown that cortisol can potentiate estrogen-induced ZP synthesis in salmonids, and now we show that this is not the case in the gilthead seabream. The present study shows for the first time the endocrine regulation of a teleost ZPX isoform, and demonstrates the dual-organ transcriptional activities of all the ZP proteins in one species.

  • 229.
    Musa, Klefah A. K.
    et al.
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Theoretical assessment of naphazoline redoxchemistry and photochemistry2007In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 111, no 15, p. 3977-3981Article in journal (Refereed)
    Abstract [en]

    The imidazoline derivative naphazoline (2-(1-naphtylmethyl)-2-imidazoline) is an α2-adrenergic agonist used as non-prescription eye and nasal preparations. Besides its functionality in generating vascoconstriction and decongestion in the patient, the toxicity, ROS generating capability, and recently also possible antioxidant capacity of the compound have been reported in the literature. In the current work the structural and electronic features of the drug are explored, using computational chemical tools. Electron affinities, ionization potentials, and excitation energies are reported, as well as charge and spin distributions of various forms of the drug. The difference in photochemical behavior between the protonated and unprotonated (basic) species is explained by the molecular orbital distributions, allowing for efficient excitation quenching in the basic structure but clear naphthalene to imidazolene charge transfer upon HOMO→ LUMO excitation in the protonated form, enabling larger intersystem crossing capability to the imidazole localized excited triplet and a resulting higher singlet oxygen quantum yield.

  • 230.
    Musa, Klefah A. K.
    et al.
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Theoretical Study of Ibuprofen Phototoxicity2007In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 111, no 46, p. 13345-13352Article in journal (Refereed)
    Abstract [en]

    The photochemical properties and degradation of the common nonsteroid anti-inflammatory drug ibuprofen is studied by means of hybrid density functional theory. Computed energies and properties of various species show that the deprotonated form dominates at physiological pH, and that the species will not be able to decarboxylate from a singlet excited state. Instead, decarboxylation will occur, with very high efficiency, provided the deprotonated compound can undergo intersystem crossing from an excited singlet to its excited triplet state. In the triplet state, the C−C bond connecting the carboxyl group is elongated, and the CO2 moiety detaches with a free energy barrier of less than 0.5 kcal/mol. Depending on the local environment, the decarboxylated product can then either be quenched through intersystem crossing (involving the possible formation of singlet oxygen) and protonation, or serve as an efficient source for superoxide anions and the formation of a peroxyl radical that will initiate lipid peroxidation.

  • 231.
    Musa, Klefah A K
    et al.
    Örebro University, Department of Natural Sciences.
    Matxain, Jon M
    Örebro University, Department of Natural Sciences.
    Eriksson, Leif A
    Örebro University, Department of Natural Sciences.
    Mechanism of Photoinduced Decomposition of Ketoprofen2007In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 50, no 8, p. 1735-1743Article in journal (Refereed)
    Abstract [en]

    UV-induced decarboxylation of the NSAID ketoprofen, followed by activation of molecular oxygen or formation of a decarboxylated peroxide adduct, is explored using computational quantum chemistry. The excited energy surfaces reveal that the neutral species will not decarboxylate, whereas the deprotonated acid decarboxylates spontaneously in the triplet state, and with an associated 3-5 kcal/mol barrier from several low-lying excited singlet states. The observed long lifetimes of the decarboxylated anion is explained in terms of the high stability of the triplet benzoyl ethyl species with protonated carbonylic oxygen, from which there is no obvious decay channel. Mechanisms for the generation of singlet oxygen and superoxide are discussed in detail. Addition of molecular oxygen to give the corresponding peroxyl radical capable of initiating propagating lipid peroxidation reactions is also explored. The computed data explains all features of the observed experimental observations made to date on the photodegradation of ketoprofen.

  • 232.
    Musa, Klefah A.K.
    Örebro University, Department of Natural Sciences.
    Theoretical studies of photodynamic drugs and phototoxic reactions2007Licentiate thesis, monograph (Other academic)
  • 233. Nambu, K.
    et al.
    van Hees, Patrick A. W.
    Jones, D. L.
    Örebro University, Department of Natural Sciences.
    Vinogradoff, S.
    Lundström, U. S.
    Composition of organic solutes and respiration in soils derived from alkaline and non-alkaline parent materials2008In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 144, no 3-4, p. 468-477Article in journal (Refereed)
    Abstract [en]

    Parent material greatly influences pedogenesis and soil nutrient availability and consequently we hypothesized that it would significantly affect the amount of organic solutes in soil, many of which have been implicated in rhizosphere processes linked to plant nutrient uptake. Consequently, we investigated the influence of two contrasting parent materials in which calcite was present or absent (alkaline and non-alkaline soils) on the concentrations of dissolved organic carbon (DOC), low-molecular weight organic acids (LMWOA) and glucose in soil solution. Both soils were under Norway spruce. The dynamics of LMWOAs in soil were also investigated using 14C-labelled citrate and oxalate. Some of the mineral horizons of the alkaline soils showed significantly higher concentrations of DOC, phenolics, and fumarate in soil solution and also a higher basal respiration. No major differences were seen in organic solute status in the organic horizons of the two soil types. LMWOAs were present at low concentrations in soil solution (< 1 to 25 ΌM). Their mineralization rate significantly decreased with soil depth, however, overall neither their concentration or half-life in soil was markedly affected by parent material. The alkaline soils had significantly higher CO2-to-soil organic C (SOC) ratios, and consequently SOC in the alkaline soils did not seem more chemically stable against mineralization. Considering possible DOC and CO2 efflux rates it was suggested that the equal or larger SOC stocks in alkaline mineral soils were most likely linked to a higher net primary productivity. In conclusion, our study found that parent material exerted only a small effect on the concentration and dynamics of organic solutes in soil solution. This suggests that in comparison to other factors (e.g. vegetation cover, climate etc) parent material may not be a major regulator of the organic solute pool in soil. © 2008 Elsevier B.V. All rights reserved.

  • 234.
    Nehrenheim, Emma
    et al.
    Department of Public Technology, Mälardalen University, Västerås, Sweden.
    Odlare, Monica
    Mälardalen University, Västerås, Sweden.
    Eriksson, P
    Mälardalen University, Västerås, Sweden.
    Allard, Bert
    Örebro University, Department of Natural Sciences.
    Simultaneous treatment of TNT and heavy metals in waste eater from demilitarization industry by using pine bark (Pinus silvestris)2008Conference paper (Refereed)
  • 235.
    Norrman, Eva
    Örebro University, Department of Natural Sciences.
    Optimisation of radiographic imaging by means of factorial experiments2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the optimisation process of radiographic imaging, factorial designed experiments can be applied. The parameters (factors) are varied together instead of one at a time, making it possible to discover interactions between the factors as well as main influences of them on the result variable. A 2k design implies having k number of factors each one set to two different levels (low and high).

    A computer program, CoCIQ, designed to automatically analyse and evaluate test images of a contrast-detail phantom, was evaluated and adjusted to clinical situations using a flat panel detector. The program gives a quantified measurement of image quality by calculating an Image Quality Figure (IQF) for the X-ray image. It was shown that the program produces IQF with small variations. It was also found that there was a strong linear statistical relation between the computerised evaluation and the evaluation performed by human observers.

    2k factorial experiments were evaluated by investigating the influence of tube potential, tube loading, focus size and filtration on the result variables IQF, Kerma Area Product (KAP) and effective dose using a flat panel detector. It was found that the result variables were mainly influenced by tube loading, tube potential and filtration. Interactions between tube potential and filtration as well as between tube loading and filtration were observed, too. This work demonstrates that accepted knowledge was reproduced and that the effects of interactions between parameters were revealed.

    Extended 2k experiments were then applied at three different optimisation procedures. Two studies were performed using a flat panel detector for lumbar spine radiography. The aim was to find optimal settings for tube potential, system sensitivity and filtration for different sized patients and, in a separate study, to investigate the effect of the image post processing parameters and the possibility for dose reduction by adjusting these. The parameters are ROI (Region Of Interest) density, gamma, detail contrast enhancement, unsharp masking, kernel size and noise compensation.

    After determining the optimal settings from these experiments, X-ray images of the lumbar spine of an Alderson phantom were acquired and evaluated in a visual grading analysis (VGA).

    The results illustrated that the image quality was maintained at a lower effective dose by operating with a reduced tube potential and increased sensitivity of the X-ray system.

    The experiments on image post process parameters revealed their influence on image quality and indicated that image quality could be improved by changing the settings of the process parameters.

    Factorial experiments were also performed, using a multislice CT scanner to investigate the possibility for dose reduction at paediatric head examinations. An anthropomorphic phantom simulating a one-year-old child was scanned using different settings of tube potential, tube loading and reconstruction filter.

    The study showed that a 25 % reduction of dose was possible with maintained image quality by reducing the tube loading.

    Factorial designed experiments provide an effective method to simultaneously predict the influence of various parameters on image quality and radiation dose in the optimisation in diagnostic radiology.

    List of papers
    1. A clinical evaluation of the image quality computer program, CoCIQ
    Open this publication in new window or tab >>A clinical evaluation of the image quality computer program, CoCIQ
    2005 (English)In: Journal of digital imaging, ISSN 0897-1889, E-ISSN 1618-727X, Vol. 18, no 2, p. 138-144Article in journal (Refereed) Published
    Abstract [en]

    To provide an objective way of measuring image quality, a computer program was designed that automatically analyzes the test images of a contrast-detail (CD) phantom. The program gives a quantified measurement of image quality by calculating an Image Quality Figure (IQF). The aim of this work was to evaluate the program and adjust it to clinical situations in order to find the detectable level where the program gives a reliable figure of the contrast resolution. The program was applied on a large variety of images with lumbar spine and urographic parameters, from very low to very high image qualities. It was shown that the computer program produces IQFs with small variations and there were a strong linear statistical relation between the computerized evaluation and the evaluation performed by human observers (R2 = 0.98). This method offers a fast and easy way of conducting image quality evaluations.

    National Category
    Physical Sciences
    Research subject
    Physics
    Identifiers
    urn:nbn:se:oru:diva-2863 (URN)10.1007/s10278-004-1036-0 (DOI)
    Available from: 2007-12-28 Created: 2007-12-28 Last updated: 2017-12-14Bibliographically approved
    2. A factorial experiment on image quality and radiation dose
    Open this publication in new window or tab >>A factorial experiment on image quality and radiation dose
    2005 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 114, no 1-3, p. 246-252Article in journal (Refereed) Published
    Abstract [en]

    To find if factorial experiments can be used in the optimisation of diagnostic imaging, a factorial experiment was performed to investigate some of the factors that influence image quality, kerma area product (KAP) and effective dose (E). In a factorial experiment the factors are varied together instead of one at a time, making it possible to discover interactions between the factors as well as major effects. The factors studied were tube potential, tube loading, focus size and filtration. Each factor was set to two levels (low and high). The influence of the factors on the response variables (image quality, KAP and E) was studied using a direct digital detector. The major effects of each factor on the response variables were estimated as well as the interaction effects between factors. The image quality, KAP and E were mainly influenced by tube loading, tube potential and filtration. There were some active interactions, for example, between tube potential and filtration and between tube loading and filtration. The study shows that factorial experiments can be used to predict the influence of various parameters on image quality and radiation dose.

    National Category
    Physical Sciences
    Research subject
    Physics
    Identifiers
    urn:nbn:se:oru:diva-2864 (URN)10.1093/rpd/nch557 (DOI)
    Available from: 2007-12-28 Created: 2007-12-28 Last updated: 2017-12-14Bibliographically approved
    3. Optimising the tube potential for lumbar spine radiography using a flat-panel digital detector
    Open this publication in new window or tab >>Optimising the tube potential for lumbar spine radiography using a flat-panel digital detector
    (English)Manuscript (preprint) (Other academic)
    National Category
    Physical Sciences
    Research subject
    Physics
    Identifiers
    urn:nbn:se:oru:diva-2865 (URN)
    Available from: 2007-12-28 Created: 2007-12-28 Last updated: 2017-10-18Bibliographically approved
    4. Optimization of image process parameters through factorial experiments using a flat panel detector
    Open this publication in new window or tab >>Optimization of image process parameters through factorial experiments using a flat panel detector
    2007 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 52, no 17, p. 5263-5276Article in journal (Refereed) Published
    Abstract [en]

    In the optimization process of lumbar spine examinations, factorial experiments were performed addressing the question of whether the effective dose can be reduced and the image quality maintained by adjusting the image processing parameters. A 2(k)-factorial design was used which is a systematic and effective method of investigating the influence of many parameters on a result variable. Radiographic images of a Contrast Detail phantom were exposed using the default settings of the process parameters for lumbar spine examinations. The image was processed using different settings of the process parameters. The parameters studied were ROI density, gamma, detail contrast enhancement (DCE), noise compensation, unsharp masking and unsharp masking kernel (UMK). The images were computer analysed and an image quality figure (IQF) was calculated and used as a measurement of the image quality. The parameters with the largest influence on image quality were noise compensation, unsharp masking, unsharp masking kernel and detail contrast enhancement. There was an interaction between unsharp masking and kernel indicating that increasing the unsharp masking improved the image quality when combined with a large kernel size. Combined with a small kernel size however the unsharp masking had a deteriorating effect. Performing a factorial experiment gave an overview of how the image quality was influenced by image processing. By adjusting the level of noise compensation, unsharp masking and kernel, the IQF was improved to a 30% lower effective dose.

    Place, publisher, year, edition, pages
    Bristol: IOP publishing, 2007
    Keywords
    Quality, Coefficients, Radiography, Reduction, Urography
    National Category
    Natural Sciences Physical Sciences Medical and Health Sciences Physiology Radiology, Nuclear Medicine and Medical Imaging
    Research subject
    Physics; Medicine; Radio Physics
    Identifiers
    urn:nbn:se:oru:diva-2866 (URN)10.1088/0031-9155/52/17/011 (DOI)
    Available from: 2007-12-28 Created: 2007-12-28 Last updated: 2018-01-13Bibliographically approved
    5. Optimisation of paediatric CT head examinations through factorial experiments
    Open this publication in new window or tab >>Optimisation of paediatric CT head examinations through factorial experiments
    (English)Manuscript (Other academic)
    National Category
    Physical Sciences
    Research subject
    Physics
    Identifiers
    urn:nbn:se:oru:diva-2867 (URN)
    Available from: 2007-12-28 Created: 2007-12-28 Last updated: 2017-10-18Bibliographically approved
  • 236.
    Norrman, Eva
    et al.
    Örebro University, Department of Natural Sciences.
    Geijer, Håkan
    Persliden, Jan
    Örebro University, School of Health and Medical Sciences.
    Optimization of image process parameters through factorial experiments using a flat panel detector2007In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 52, no 17, p. 5263-5276Article in journal (Refereed)
    Abstract [en]

    In the optimization process of lumbar spine examinations, factorial experiments were performed addressing the question of whether the effective dose can be reduced and the image quality maintained by adjusting the image processing parameters. A 2(k)-factorial design was used which is a systematic and effective method of investigating the influence of many parameters on a result variable. Radiographic images of a Contrast Detail phantom were exposed using the default settings of the process parameters for lumbar spine examinations. The image was processed using different settings of the process parameters. The parameters studied were ROI density, gamma, detail contrast enhancement (DCE), noise compensation, unsharp masking and unsharp masking kernel (UMK). The images were computer analysed and an image quality figure (IQF) was calculated and used as a measurement of the image quality. The parameters with the largest influence on image quality were noise compensation, unsharp masking, unsharp masking kernel and detail contrast enhancement. There was an interaction between unsharp masking and kernel indicating that increasing the unsharp masking improved the image quality when combined with a large kernel size. Combined with a small kernel size however the unsharp masking had a deteriorating effect. Performing a factorial experiment gave an overview of how the image quality was influenced by image processing. By adjusting the level of noise compensation, unsharp masking and kernel, the IQF was improved to a 30% lower effective dose.

  • 237.
    Norrman, Eva
    et al.
    Örebro University, Department of Natural Sciences.
    Gårdestig, Magnus
    Persliden, Jan
    Geijer, Håkan
    A clinical evaluation of the image quality computer program, CoCIQ2005In: Journal of digital imaging, ISSN 0897-1889, E-ISSN 1618-727X, Vol. 18, no 2, p. 138-144Article in journal (Refereed)
    Abstract [en]

    To provide an objective way of measuring image quality, a computer program was designed that automatically analyzes the test images of a contrast-detail (CD) phantom. The program gives a quantified measurement of image quality by calculating an Image Quality Figure (IQF). The aim of this work was to evaluate the program and adjust it to clinical situations in order to find the detectable level where the program gives a reliable figure of the contrast resolution. The program was applied on a large variety of images with lumbar spine and urographic parameters, from very low to very high image qualities. It was shown that the computer program produces IQFs with small variations and there were a strong linear statistical relation between the computerized evaluation and the evaluation performed by human observers (R2 = 0.98). This method offers a fast and easy way of conducting image quality evaluations.

  • 238.
    Norrman, Eva
    et al.
    Örebro University, Department of Natural Sciences.
    Persliden, Jan
    A factorial experiment on image quality and radiation dose2005In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 114, no 1-3, p. 246-252Article in journal (Refereed)
    Abstract [en]

    To find if factorial experiments can be used in the optimisation of diagnostic imaging, a factorial experiment was performed to investigate some of the factors that influence image quality, kerma area product (KAP) and effective dose (E). In a factorial experiment the factors are varied together instead of one at a time, making it possible to discover interactions between the factors as well as major effects. The factors studied were tube potential, tube loading, focus size and filtration. Each factor was set to two levels (low and high). The influence of the factors on the response variables (image quality, KAP and E) was studied using a direct digital detector. The major effects of each factor on the response variables were estimated as well as the interaction effects between factors. The image quality, KAP and E were mainly influenced by tube loading, tube potential and filtration. There were some active interactions, for example, between tube potential and filtration and between tube loading and filtration. The study shows that factorial experiments can be used to predict the influence of various parameters on image quality and radiation dose.

  • 239.
    Norrman, Eva
    et al.
    Örebro University, Department of Natural Sciences.
    Persliden, Jan
    Optimisation of paediatric CT head examinations through factorial experimentsManuscript (Other academic)
  • 240. Näsholm, Torgny
    et al.
    Ekblad, Alf
    Örebro University, Department of Natural Sciences.
    Nordin, Annika
    Giesler, Reiner
    Högberg, Mona
    Högberg, Peter
    Boreal forest plants take up organic nitrogen1998In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 392, no 6679, p. 914-916Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Plant growth in the boreal forest, the largest terrestrial biome, is generally limited by the availability of nitrogen. The presumed cause of this limitation is slow mineralization of soil organic nitrogen1,2. Here we demonstrate, to our knowledge for the first time, the uptake of organic nitrogen in the field by the trees Pinus sylvestris and Picea abies, the dwarf shrub Vaccinium myrtillus and the grass Deschampsia flexuosa. These results show that these plants, irrespective of their different types of root–fungal associations (mycorrhiza), bypass nitrogen mineralization. A trace of the amino acid glycine, labelled with the stable isotopes 13C and 15N, was injected into the organic (mor) layer of an old successional boreal coniferous forest. Ratios of 13C:15N in the roots showed that at least 91, 64 and 42% of the nitrogen from the absorbed glycine was taken up in intact glycine by the dwarf shrub, the grass and the trees, respectively. Rates of glycine uptake were similar to those of 15N-ammonium. Our data indicate that organic nitrogen is important for these different plants, even when they are competing with each other and with non-symbiotic microorganisms. This has major implications for our understanding of the effects of nitrogen deposition, global warming and intensified forestry.

  • 241.
    Oberstedt, Andreas
    et al.
    Örebro University, Department of Natural Sciences.
    Birgersson, Evert
    Örebro University, Department of Natural Sciences.
    Tovesson, Fredrik
    Örebro University, Department of Natural Sciences.
    Hambsch, Franz-Josef
    Oberstedt, Stephan
    Fritsch, Volker
    Vladuca, Gheorghita
    Tudora, Annabella
    Fogelberg, Birger
    Ramström, Elisabet
    Neutron reaction cross section data for advanced nuclear applications2005In: Proceedings of the 11th international topical meeting on nuclear reactor thermal-hydraulics (NURETH-11): 262, 2005, p. 1-9Conference paper (Refereed)
  • 242.
    Oberstedt, Andreas
    et al.
    Örebro University, Department of Natural Sciences.
    Oberstedt, Stephan
    Energy degrader technique for light-charged particle spectroscopy at LOHENGRIN2007In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 570, no 1, p. 51-54Article in journal (Refereed)
    Abstract [en]

    The recoil mass-separator LOHENGRIN at Institute Laue-Langevin was originally designed for the spectrometry of binary fission fragments. Nevertheless, it was also used in the past for measuring light-charged particles from ternary fission. However, due to the electric field settings the energy distribution of the lightest particles was not completely accessible, which made the determination of mean kinetic energies, widths and, hence, emission yields difficult. In this paper we present an energy degrader technique that allows for the measurement of the entire energy spectrum of even the lightest ternary particles with LOHENGRIN.

  • 243.
    Oberstedt, Andreas
    et al.
    Örebro University, Department of Natural Sciences.
    Oberstedt, Stephan
    Birgersson, Evert
    Örebro University, Department of Natural Sciences.
    Hambsch, Franz-Josef
    Fritsch, Volker
    Lövestam, Göran
    Vladuca, Gheorghita
    Tudora, Annabella
    Kornilov, Nikolai
    Recent results on the neutron-induced fission cross-section of 231Pa2005In: Proceedings of the 3rd international workshop on nuclear fission and fission-product spectroscopy, American Institute of Physics , 2005, p. 27-30Conference paper (Refereed)
    Abstract [en]

    The cross-section for the neutron-induced fission of 231Pa has recently been measured from the threshold to En = 3.5 MeV. The experimental results are described in terms of extended statistical model calculations.

  • 244.
    Oberstedt, Andreas
    et al.
    Örebro University, Department of Natural Sciences.
    Oberstedt, Stephan
    Gawrys, Michael
    Kornilov, Nikolai
    Identification of a Shape Isomer in 235U2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 4, p. 1-4Article in journal (Refereed)
    Abstract [en]

    The shape isomer in 235U has been searched for in a neutron-induced fission experiment on 234U, which was performed at the isomer spectrometer NEPTUNE of the EC-JRC IRMM. A neutron source, with a tunable pulse frequency in the Hz to kHz range and its individually adjustable neutron pulse width in connection with an appropriate detector system turned out to be the ideal instrument to perform an isomer search, when decay half-lives above 100 us are expected. From the delayed fission events observed for two different NEPTUNE settings and at mean incident neutron energies En = 0.95 and 1.27 MeV the isomeric fission half-life could be determined to be T_1/2 = (3.6 ± 1.8) ms. The corresponding cross section was determined to sigma_if = (10 ± 8) ub. With these results an experimental confirmation for the existence of a superdeformed shape isomer in odd-uranium isotopes is given for the first time.

  • 245. Oberstedt, Stephan
    et al.
    Oberstedt, Andreas
    Örebro University, Department of Natural Sciences.
    Hambsch, Franz-Josef
    Fritsch, Volker
    Lövestam, Göran
    Kornilov, Nikolai
    New results on the neutron-induced fission cross-section of 231Pa for incident neutron energies En = 0.8 to 3.5 MeV2005In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 32, no 17, p. 1867-1874Article in journal (Refereed)
  • 246. Oberstedt, Stephan
    et al.
    Oberstedt, Andreas
    Örebro University, Department of Natural Sciences.
    Hambsch, Franz-Josef
    Fritsch, Volker
    Vladuca, Gheorghita
    Tudora, Annabella
    Neutron-induced fission cross-section of 231Pa2006In: Proceedings of NEMEA-2 Workshop on Neutron Measurements, Evaluations and Applications - 2, October 20-23, 2004, Bucharest, Rumania, EUR Report 22136 EN, 2006Conference paper (Refereed)
  • 247. Oberstedt, Stephan
    et al.
    Oberstedt, Andreas
    Örebro University, Department of Natural Sciences.
    Rochman, Dimitri
    Gönnenwein, Friedrich
    Tsekhanovich, Igor
    Becker, Julia
    Örebro University, Department of Natural Sciences.
    Sartz, Annika
    Örebro University, Department of Natural Sciences.
    Bax, Hugo
    Hambsch, Franz-Josef
    Raman, Subramanian
    Light charged particle emission in the reaction 251Cf(nth, f)2005In: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 761, no 3-4, p. 173-189Article in journal (Refereed)
    Abstract [en]

    High resolution measurements of light charged particles (LCP) emitted in thermal neutron-induced fission of 252Cf ∗ (E=6.2 MeV) have been performed with the recoil mass-separator LOHENGRIN. For this compound nuclear system emission yields of LCPs, their mean kinetic energies and widths have been obtained for 8 isotopes with nuclear charges Z⩾2. For 13 further isotopes the emission yields were estimated on the basis of systematics on their kinetic energy distributions. 34Al and 36Si emission has been observed for the first time in thermal neutron-induced fission.

  • 248. Olsman, H.
    et al.
    Johansson, Inger
    Örebro University, Department of Natural Sciences.
    Dioxin-like compounds in incineration ashes: a comparison between bioanalytical screening and chemical analysis of PAHsManuscript (preprint) (Other academic)
  • 249.
    Olsman, Helena
    Örebro University, Department of Natural Sciences.
    Bioassay analysis of dioxin-like compounds: response interactions and environmental transformation of Ah receptor agonists2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dioxin-like compounds mediate their toxicity by binding to the aryl hydrocarbon receptor (AhR) and through this receptor a cascade of biochemical and toxic events are triggered. Mechanism-specific dioxin bioassays utilise the AhR coupled induction of endogenous CYP1A proteins or reporter gene systems for detection of dioxin-like compounds and other AhR ligands. The use of mechanism-specific in vitro bioassays as a complement or alternative to conventional GC-MS analysis of dioxin-like compounds has gained acceptance over the last years and is also in part a search for a tool for rapid and facilitated dioxin risk assessment.

    This thesis includes several applications for bioassay analysis using the two bioassays Dioxin Responsive Chemically Activated Luciferase eXpression assay (DR-CALUX) and Chick Embryo Liver Culture Assay for Dioxins (CELCAD). The two dioxin bioassays were used to study the AhR mediated induction for single compounds, as well as for mixtures of AhR active compounds in different sample matrices, also including studies of the influence of clean-up methods and fractionation on bioassay response.

    Bioanalysis gave valuable information on the toxicological relevance of decaBDE UV photoproducts. The bioassay methodology was able to reflect the actual variation in PBDF formation, and enabled a good estimation of toxicity of the congeners formed, regardless of chemical identification and congener specific potency data. The congeners formed had low potencies compared to the most toxic 2,3,7,8-substituted congeners, but the high concentrations resulted in considerable levels of TEQs.

    For complex samples like organic household waste digestates it is advisable to use both bio- and chemical analysis, for confirmation of results, as far as possible. The bioassay-directed fractionation approach requires several fractionation steps (i.e. different methods) in order to obtain well-defined fractions, from which detailed conclusions can be drawn.

    Also, proper analysis of human adipose tissue, although by far less complex than organic household waste, requires fractionation. Bioanalysis of these samples showed large deviations from the additivity assumption applied in the TEF calculation from chemical analysis. Thus, it is not clear how to interpret the bioassay results in relation to chemical results, although both methods gave the same information on relative levels of AhR agonists and showed good reproducibility.

    Both DR-CALUX and CELCAD proved to be useful for AhR agonist analysis in mixtures and for single compounds. The DR-CALUX enables more rapid analysis of large number of samples and is therefore, a more suitable tool for AhR agonist detection, whereas CELCAD has more limitations and is more suitable for the study of AhR mediated toxicity with special emphasis on avian species. In vitro bioassays have many implications for the analysis of AhR agonists, yielding reliable and reproducible results, provided that proper clean-up and fractionation of samples is applied. Bioassays enable fast determinations of total or integrated effects of AhR ligands in samples, as well as specific potency studies. Thus, bioassays are in all a valuable and necessary complement to chemical analysis.

    List of papers
    1. Fractionation and determination of Ah receptor (AhR) agonists in organic waste after anaerobic biodegradation and in batch experiments with PCB and decaBDE
    Open this publication in new window or tab >>Fractionation and determination of Ah receptor (AhR) agonists in organic waste after anaerobic biodegradation and in batch experiments with PCB and decaBDE
    Show others...
    (English)Manuscript (Other academic)
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-2934 (URN)
    Available from: 2005-11-04 Created: 2005-11-04 Last updated: 2017-10-18Bibliographically approved
    2. Ah receptor agonists in UV-exposed toluene solutions of decabromodiphenyl ether (decaBDE) and in soils contaminated with polybrominated diphenyl ethers (PBDEs)
    Open this publication in new window or tab >>Ah receptor agonists in UV-exposed toluene solutions of decabromodiphenyl ether (decaBDE) and in soils contaminated with polybrominated diphenyl ethers (PBDEs)
    Show others...
    2006 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 13, no 3, p. 161-169Article in journal (Refereed) Published
    Abstract [en]

    GOAL, SCOPE AND BACKGROUND: The use of polybrominated diphenyl ethers (PBDEs) as flame retardants increases the risk for emissions of other brominated compounds, such as polybrominated dibenzodioxins (PBDDs) and dibenzofurans (PBDFs). The large homology in structure of PBDD/Fs and mechanism of toxic action, i.e. the capacity to activate the Ah receptor (AhR) pathway, compared to their well-studied chlorinated analogues, justifies a raised concern to study the environmental levels and fate of these compounds. Decabromodiphenyl ether (decaBDE) is the most widely used PBDE today. Studies on photolytic debromination of decaBDE in organic solvents have shown debromination of decaBDE, as well as formation of PBDFs. However, little is known about the transformation mechanisms and there are only scarce data on photoproducts and PBDE transformation in environmentally relevant matrices. In this study, mechanism-specific dioxin bioassays were used to study photolytic formation of AhR agonists in toluene solutions of decaBDE. In addition, the influence of irradiation time and UV-light wavelength on the formation was studied. PBDE congener patterns and presence of PBDD/Fs were analysed. Further, AhR agonists were analysed in agricultural soils contaminated with PBDEs. Soils were also exposed to UV-light to study changes in AhR agonist levels. METHODS: Toluene solutions of decaBDE were irradiated using three different spectra of UV-light, simulating UV-A (320-400 nm), UV-AB (280-400 nm), and UV-ABC (250-400 nm). Additionally, decaBDE solutions were exposed to narrow wavelength intervals (10 nm bandwidth) with the central wavelengths 280, 290, 300, 310, 320, 330, 340, 350, 360 nm. AhR agonists in decaBDE solutions were analysed with two different bioassays, the chick embryo liver-cell assay for dioxins (Celcad) and the dioxin responsive, chemically activated luciferase expression assay (DR-Calux). Also, the decaBDE solutions were analysed with LRGC-LRMS to obtain PBDE congener patterns for breakdown of decaBDE, and with HRGC-HRMS, for presence of PBDD/Fs. Four soils were exposed to UV-AB light, under both dry and moist conditions. Levels of AhR agonists in soil extract fractions, before and after UV-exposure, were analysed with the DR-Calux. RESULTS AND DISCUSSION: Significant levels of photoproducts able to activate the AhR pathway, up to 31 ng bio-TEQ/ml, were formed in UV-exposed decaBDE solutions. The transformation yield of decaBDE into AhR agonists was estimated to be at the 0.1%-level, on a molar basis. The net formation was highly dependent on wavelength, with the sample irradiated at 330 nm showing the highest level of dioxin-like activity. No activity was detected in controls. PBDE analysis confirmed decaBDE degradation and a clear time-dependent pattern for debromination of PBDE congeners. AhR agonist effect in the recalcitrant fractions of the soils corresponded to the levels of chemically derived TEQs, based only on chlorinated dioxin-like compounds in an earlier study. It was concluded that no significant levels of other AhR agonists, e.g. PBDFs, were accumulated in the soil. UV-light caused changes in AhR-mediated activity in the more polar and less persistent fractions of the soils, but it is not known which compounds are responsible for this. RECOMMENDATIONS AND PERSPECTIVES: The laboratory experiments in this study show that high levels of AhR agonists can be formed as photoproducts of decaBDE and it is important to elucidate if and under which conditions this might occur in nature. However, soil analysis indicates that photoproducts of PBDE do not contribute to the accumulated levels of persistent dioxin-like compounds in agricultural soil. Still, more data is needed to fully estimate the environmental importance of PBDE photolysis and occurrence of its photoproducts in other environmental compartments. Analysis with dioxin bioassays enabled us to gather information about photoproducts formed from decaBDE even though the exact identities of these compounds were not known. CONCLUSION: Bioassays are valuable for studying environmental transformation processes like this, where chemical analysis and subsequent toxicological evaluation requires available standard compounds and information on toxicological potency. The use of bioassays allows a rapid evaluation of toxicological relevance.

    Keywords
    Animals, Biological Assay, Cell Line; Tumor, Chick Embryo, Flame Retardants/radiation effects/toxicity, Phenyl Ethers/*chemistry/radiation effects/toxicity, Photolysis, Polybrominated Biphenyls/*chemistry/radiation effects/toxicity, Rats, Receptors; Aryl Hydrocarbon/*agonists, Soil Pollutants/radiation effects/toxicity, Solutions, Spectrometry; Mass; Electrospray Ionization, Toluene/chemistry, Ultraviolet Rays
    National Category
    Biological Sciences Chemical Sciences
    Research subject
    Biology; Chemistry
    Identifiers
    urn:nbn:se:oru:diva-4132 (URN)10.1065/espr2005.08.280 (DOI)16758706 (PubMedID)
    Available from: 2008-11-12 Created: 2008-11-12 Last updated: 2017-12-14Bibliographically approved
    3. Chemical and toxicological characterisation of PBDFs from photolytic decomposition of decaBDE in toluene
    Open this publication in new window or tab >>Chemical and toxicological characterisation of PBDFs from photolytic decomposition of decaBDE in toluene
    (English)Manuscript (Other academic)
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-2936 (URN)
    Available from: 2005-11-04 Created: 2005-11-04 Last updated: 2017-10-18Bibliographically approved
    4. Differences in Ah receptor mediated response for eighteen polybrominated and mixed halogenated dibenzo-p-dioxins and -furans in cell lines from four different species
    Open this publication in new window or tab >>Differences in Ah receptor mediated response for eighteen polybrominated and mixed halogenated dibenzo-p-dioxins and -furans in cell lines from four different species
    Show others...
    (English)Manuscript (Other academic)
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-2937 (URN)
    Available from: 2005-11-04 Created: 2005-11-04 Last updated: 2017-10-18Bibliographically approved
    5. CALUX-TEQs, PCDD/F and PCB in SFE-extracts of human adipose tissue from breast cancer patients
    Open this publication in new window or tab >>CALUX-TEQs, PCDD/F and PCB in SFE-extracts of human adipose tissue from breast cancer patients
    Show others...
    (English)Manuscript (Other academic)
    National Category
    Biological Sciences
    Research subject
    Biology
    Identifiers
    urn:nbn:se:oru:diva-2938 (URN)
    Available from: 2005-11-04 Created: 2005-11-04 Last updated: 2017-10-18Bibliographically approved
  • 250.
    Olsman, Helena
    et al.
    Örebro University, Department of Natural Sciences.
    Hagberg, Jessika
    Örebro University, Department of Natural Sciences.
    Kalbin, Georgi
    Örebro University, Department of Natural Sciences.
    Julander, Anneli
    Örebro University, Department of Natural Sciences.
    van Bavel, Bert
    Örebro University, Department of Natural Sciences.
    Strid, Åke
    Örebro University, Department of Natural Sciences.
    Tysklind, Mats
    Engwall, Magnus
    Örebro University, Department of Natural Sciences.
    Ah receptor agonists in UV-exposed toluene solutions of decabromodiphenyl ether (decaBDE) and in soils contaminated with polybrominated diphenyl ethers (PBDEs)2006In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 13, no 3, p. 161-169Article in journal (Refereed)
    Abstract [en]

    GOAL, SCOPE AND BACKGROUND: The use of polybrominated diphenyl ethers (PBDEs) as flame retardants increases the risk for emissions of other brominated compounds, such as polybrominated dibenzodioxins (PBDDs) and dibenzofurans (PBDFs). The large homology in structure of PBDD/Fs and mechanism of toxic action, i.e. the capacity to activate the Ah receptor (AhR) pathway, compared to their well-studied chlorinated analogues, justifies a raised concern to study the environmental levels and fate of these compounds. Decabromodiphenyl ether (decaBDE) is the most widely used PBDE today. Studies on photolytic debromination of decaBDE in organic solvents have shown debromination of decaBDE, as well as formation of PBDFs. However, little is known about the transformation mechanisms and there are only scarce data on photoproducts and PBDE transformation in environmentally relevant matrices. In this study, mechanism-specific dioxin bioassays were used to study photolytic formation of AhR agonists in toluene solutions of decaBDE. In addition, the influence of irradiation time and UV-light wavelength on the formation was studied. PBDE congener patterns and presence of PBDD/Fs were analysed. Further, AhR agonists were analysed in agricultural soils contaminated with PBDEs. Soils were also exposed to UV-light to study changes in AhR agonist levels. METHODS: Toluene solutions of decaBDE were irradiated using three different spectra of UV-light, simulating UV-A (320-400 nm), UV-AB (280-400 nm), and UV-ABC (250-400 nm). Additionally, decaBDE solutions were exposed to narrow wavelength intervals (10 nm bandwidth) with the central wavelengths 280, 290, 300, 310, 320, 330, 340, 350, 360 nm. AhR agonists in decaBDE solutions were analysed with two different bioassays, the chick embryo liver-cell assay for dioxins (Celcad) and the dioxin responsive, chemically activated luciferase expression assay (DR-Calux). Also, the decaBDE solutions were analysed with LRGC-LRMS to obtain PBDE congener patterns for breakdown of decaBDE, and with HRGC-HRMS, for presence of PBDD/Fs. Four soils were exposed to UV-AB light, under both dry and moist conditions. Levels of AhR agonists in soil extract fractions, before and after UV-exposure, were analysed with the DR-Calux. RESULTS AND DISCUSSION: Significant levels of photoproducts able to activate the AhR pathway, up to 31 ng bio-TEQ/ml, were formed in UV-exposed decaBDE solutions. The transformation yield of decaBDE into AhR agonists was estimated to be at the 0.1%-level, on a molar basis. The net formation was highly dependent on wavelength, with the sample irradiated at 330 nm showing the highest level of dioxin-like activity. No activity was detected in controls. PBDE analysis confirmed decaBDE degradation and a clear time-dependent pattern for debromination of PBDE congeners. AhR agonist effect in the recalcitrant fractions of the soils corresponded to the levels of chemically derived TEQs, based only on chlorinated dioxin-like compounds in an earlier study. It was concluded that no significant levels of other AhR agonists, e.g. PBDFs, were accumulated in the soil. UV-light caused changes in AhR-mediated activity in the more polar and less persistent fractions of the soils, but it is not known which compounds are responsible for this. RECOMMENDATIONS AND PERSPECTIVES: The laboratory experiments in this study show that high levels of AhR agonists can be formed as photoproducts of decaBDE and it is important to elucidate if and under which conditions this might occur in nature. However, soil analysis indicates that photoproducts of PBDE do not contribute to the accumulated levels of persistent dioxin-like compounds in agricultural soil. Still, more data is needed to fully estimate the environmental importance of PBDE photolysis and occurrence of its photoproducts in other environmental compartments. Analysis with dioxin bioassays enabled us to gather information about photoproducts formed from decaBDE even though the exact identities of these compounds were not known. CONCLUSION: Bioassays are valuable for studying environmental transformation processes like this, where chemical analysis and subsequent toxicological evaluation requires available standard compounds and information on toxicological potency. The use of bioassays allows a rapid evaluation of toxicological relevance.

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