| 1. |
- Andres, Britta, et al.
(författare)
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Supercapacitors with graphene coated paper electrodes
- 2012
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:2, s. 481-485
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Tidskriftsartikel (refereegranskat)abstract
- Paper based supercapacitors are prepared by stacking a paper between two graphene electrodes and soaking these in an aqueous electrolyte. We demonstrate that supercapacitors can easily be manufactured by using proven paper technologies. Several different electrode materials were compared and two types of contacting material, silver and graphite foil were tested. The influence of the paper used as separator was also investigated. The supercapacitors with a graphene-gold nanoparticle composite as electrodes showed a specific capacitance of up to 100 F/g and an energy density of 1.27 Wh/kg. The energy density can further be increased by using other electrolytes. The silver contacts showed a pseudo capacitance, which the graphite contacts did not. The papers tested had a minor effect on the capacitance, but they have an influence on the weight and the volume of the supercapacitor.
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| 2. |
- Ljunggren, Joel, et al.
(författare)
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Changes in Extracellular Amino Acids, pH and Growth when Fungi Interact at the Near-contact Level: Heterobasidion parviporum vs. Gloeophyllum sepiarium
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Heterobasidion parviporum and Gloeophyllum sepiarium are fungal species representing two different ecological niches. H. parviporum is a parasitic white-rot fungus and early colonizer of felled wood, while the brown-rot fungus G. sepiarium is an early-middle colonizer in the natural fungi succession order. In this study, we quantitatively examined the utilization of amino acids in the μM range, pH and final dry weight from common liquid glucose-malt extract medium when the two fungi were interacting at the near-contact level. An increase in glutamine concentration was observed, and lysine was utilized in a greater extent when fungi were interacting compared to when they grew on their own. Our results also show fungal interaction is a process with high variability both in pH, growth and amino acid utilization, depending on the type of interaction. A connection between the growth, according to dry weight, and pH is suggested in the interaction between H. parviporum and G. sepiarium.
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| 3. |
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| 4. |
- Vilches, Ana Paola, et al.
(författare)
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Biofuel ash addition increases ectomycorrhizal fungal exudation in pure culture
- 2018
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Ingår i: Environmental Chemistry. - 1448-2517 .- 1449-8979. ; 15:8, s. 481-492
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Tidskriftsartikel (refereegranskat)abstract
- Environmental context. Spreading recycled wood ash in forests may counteract acidification and nutrient losses, but the process may also affect symbiotic fungi in these eco-systems. We show how fungal species react when exposed to ash solutions; for example, by an increased release of organic acids and other compounds. These effects can influence pH and metal availability in forest soils treated with ash.. Recycling of wood ash may counteract acidification and losses of base cations resulting from whole-tree harvesting in boreal forest ecosystems. The effects of ash treatment on growth and exudation of eight ectomycorrhizal fungal species were investigated in this study. Six basidiomycetes and two ascomycetes were grown in liquid pure culture with different levels of ash amendments. Biomass production, pH and the exudation of 17 low-molecular-mass organic acids (LMMOAs), 23 amino acids (AAs) and 9 hydroxamate siderophores (HSs) were recorded after 1, 2 and 4 weeks of incubation. Ash did not affect fungal growth, but resulted in higher exudation of the investigated compounds, in particular LMMOAs. Ash also influenced the composition of the exudates. We measured exudation of LMMOAs and AAs up to millimolar and micromolar concentrations respectively. For example, Rhizopogon roseolus mainly produced oxalic acid, whereas Lactarius rufus and Tomentellopsis submollis produced the highest concentrations of AAs. Ferricrocin, the only HS detected, was exuded at the nanomolar level. Exudation responses were also highly species-dependent, e.g. the ascomycetous isolates that produced the largest biomass released low amounts of exudates compared with the basidiomycetes, and were the only ones producing siderophores. This growth–exudation response to ash is likely a trade-off in carbon allocation whereby the mycorrhizal fungal species invest carbon in either higher biomass production or higher exudation.
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| 5. |
- Vilches, Ana Paola, et al.
(författare)
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Direct analysis of free amino acids by mixed-mode chromatography with tandem mass spectrometry
- 2017
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Ingår i: Journal of Separation Science. - : Wiley. - 1615-9306 .- 1615-9314. ; 40:7, s. 1482-1492
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Tidskriftsartikel (refereegranskat)abstract
- We developed a straightforward, robust, and relatively fast method for the analysis of amino acids by mixed-mode high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The method does not involve derivatization and allows the detection of 21 amino acids, representing a wide range of isoelectric points, in less than 40 min. Chromatographic separation was governed by a silica-based mixed-mode column providing simultaneous hydrophobic and ion exchange separation mechanisms. The use of tandem mass spectrometry increased selectivity, reducing potential problems associated with poor selectivity in the chromatographic system. For an injection volume of 1 μL, we obtained detection limits <3 μM for the majority of analytes. For all analytes, a linearity of r > 0.99 was obtained, recovery in matrix was >86%, and the retention times were highly reproducible. The method was successfully applied to soil solution and fungal culture samples, demonstrating the advantages in successfully avoiding issues associated with high amounts of substances that may interfere with derivatization-based methods. This method represents an alternative to derivatization-based methods and can be applied in areas where sample matrices are highly complex.
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| 6. |
- Vilches, Ana Paola
(författare)
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Effects of Bio-Ash Amendments on the Metabolism of Ectomycorrhizal Fungi : A Method Development and Metabolomic Study
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Forest ecosystems have played a fundamental role in the development of our society. Since the beginning of the civilization, forest have provided us with wood as a product for construction, tools, furniture and domestic heating. The well-being of the forest is therefore fundamental to our existence. Today, our growing societies have increased energy needs; the resulting depletion of fossil reserves and the effects of their use has again shown how the forest is among the most important alternatives for sustainability of our ecosystem. In order to responsibly make this resource a key part of our energy and material supply, we need to understand how forestry practices influence the different processes taking place in the forest ecosystems.The use of raw material from forest as energy source produces huge amounts of ash. The ash contains the base cations that have once been translocated from soil to the upper parts of the trees. Ash recycling has therefore been suggested as a measure to counteract soil acidification due to extensive harvest. Since spreading of ash can have great effects on the forest, it is important to understand which these effects are and how big they might be.This thesis focuses on the effects that such an ash recycling may have on the metabolism of ectomycorrhizal fungi; that is, fungi that are able to colonize root of trees, and contribute to the acquisition of nutrients and water from soil. The work presented here utilized an in vitro metabolomic approach on eight species of ectomycorrhizal fungi normally found in boreal forests. A targeted metabolomic study addressed the effects of ash amendments on growth, external pH and the exudation of low molecular mass organic acids, amino acids and hydroxamate siderophores. This was complemented by an untargeted metabolomic study to address the effects of ash amendment on the general metabolism of the fungal species.Analyses were performed with well-established chemical methods, and some that had to be developed specifically for this thesis work. A method for the analysis of amino acids without derivatization and yet compatible with mass spectrometry had to be developed and validated. The result was a robust method that works well with external calibration, shows good long-term stability, relatively low detections limits and high sample throughput. A screening protocol for the determination of siderophores from mass spectrometry data was also established.The metabolomic studies showed that bio-ash amendment increased the exudation of low molecular mass organic compounds from all the studied species. This means that the species tended to exude more of the same compounds compared to the controls without ash. In some cases, the bio-ash also triggered the exudation of new compounds. There was some exceptions, though; bio-ash amendment had negative effects on the exudation of certain metabolites, but these negative effects were of lower magnitude compared to the positive effects.Both metabolomics studies showed a differentiation between the ascomycetes and the basidiomycetes species. The targeted metabolomic study, indicated a trade-off in the utilization of carbon for accumulation of biomass or for the exudation of low molecular mass organic compounds, in which the ascomycetes accumulated more carbon as biomass compared to the basidiomycetes. According to the untargeted metabolomic study, the ascomycetes species presented the greatest number of metabolites that were influenced significantly by ash treatment, either as increase or decrease.Adding extracted ash to the culturing medium at the beginning of the experiment increased the pH, but this was counteracted by species metabolism as exudation of organic acids correlated with a drop in external pH. Ash treatment triggered the total exudation of low molecular mass organic acids in five of the eight studied species and especially in Cortinarius glaucopus. Ash treatment also triggered the exudation of amino acids from Tomentellopsis submollis and ferricrocin from Hymenoscyphus ericae.Of note was that no metabolite significantly influenced by ash was found to be common to all species, indicating that the ash amendments mainly affected the secondary metabolism under the culturing conditions used. Additionally, the ascomycetes Hymenoscyphus ericae exuded the greatest number of metabolites affected by ash that were exuded only by a single species. Conversely, Piloderma olivaceum exuded the largest number of unique metabolites not influenced by ash.
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| 7. |
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| 8. |
- Vilches, Ana Paola, et al.
(författare)
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ENHANCED NATURAL BIODEGRADATION OF DIESEL FUEL CONTAMINANTS IN SOIL BY ADDITION OF WHEY AND NUTRIENTS
- 2010
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Ingår i: <em><em>International Conference on Natural Sciences andTechnologies for Waste and Wastewater Treatment,Remediation, Emissions Related to Climate, Environmentaland Economic Effects</em></em>. ; , s. 1001-1008
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Konferensbidrag (refereegranskat)abstract
- The contamination of soils by petroleum hydrocarbons, such as diesel fuel, has since many years been a serious environmental problem. Treatment of contaminated areas is a concern for governments and environmental authorities in several countries and efforts have been done with the purpose to eliminate this problem. Different methods have been tested and today the most common technique involves the excavation and transportation of contaminated soil to special treatment facilities. In earlier studies we have demonstrated the effect of adding organic amendments, such as fermented whey, on the biodegradation of n-alkanes in diesel contaminated soil. Non-fermented sweet whey also proved significantly to enhance the biodegradation of an aromatic substance (phenanthrene) in contaminated soil. The current paper presents the results of an in-situ field test at a former gas station in the north of Sweden. In parallel to the field study, biodegradation profiles were monitored under controlled laboratory conditions by taking soil samples from the contaminated site and spike them with diesel fuel. The experiments were carried out by adding whey and mineral nutrients (NPK) to the test area and to the laboratory samples, and monitor the degradation of hydrocarbons by gas chromatographic analysis of extracted soil samples. Significant effects on the degradation rates were achieved in the laboratory tests. For the in-situ test, however, no such positive effects could be registered.
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