| 1. |
- Ciosek Högström, Katarzyna, 1984-, et al.
(författare)
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Impact of the flame retardant additive triphenyl phosphate (TPP) on the performance of graphite/LiFePO4 cells in high power applications
- 2014
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 256, s. 430-439
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Tidskriftsartikel (refereegranskat)abstract
- This study presents an extensive characterization of a standard Li-ion battery (LiB) electrolyte containing different concentrations of the flame retardant triphenyl phosphate (TPP) in the context of high power applications. Electrolyte characterization shows only a minor decrease in the electrolyte flammability for low TPP concentrations. The addition of TPP to the electrolyte leads to increased viscosity and decreased conductivity. The solvation of the lithium ion charge carriers seem to be directly affected by the TPP addition as evidenced by Raman spectroscopy and increased mass-transport resistivity. Graphite/LiFePO4 full cell tests show the energy efficiency to decrease with the addition of TPP. Specifically, diffusion resistivity is observed to be the main source of increased losses. Furthermore, TPP influences the interface chemistry on both the positive and the negative electrode. Higher concentrations of TPP lead to thicker interface layers on LiFePO4. Even though TPP is not electrochemically reduced on graphite, it does participate in SEI formation. TPP cannot be considered a suitable flame retardant for high power applications as there is only a minor impact of TPP on the flammability of the electrolyte for low concentrations of TPP, and a significant increase in polarization is observed for higher concentrations of TPP. (C) 2014 Elsevier B.V. All rights reserved.
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| 2. |
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| 3. |
- Mitra, Aditee, et al.
(författare)
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Defining Planktonic Protist Functional Groups on Mechanisms for Energy and Nutrient Acquisition : Incorporation of Diverse Mixotrophic Strategies
- 2016
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Ingår i: Protist. - : Elsevier BV. - 1434-4610 .- 1618-0941. ; 167:2, s. 106-120
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Tidskriftsartikel (refereegranskat)abstract
- Arranging organisms into functional groups aids ecological research by grouping organisms (irrespective of phylogenetic origin) that interact with environmental factors in similar ways. Planktonic protists traditionally have been split between photoautotrophic "phytoplankton" and phagotrophic "microzooplankton". However, there is a growing recognition of the importance of mixotrophy in euphotic aquatic systems, where many protists often combine photoautotrophic and phagotrophic modes of nutrition. Such organisms do not align with the traditional dichotomy of phytoplankton and microzooplankton. To reflect this understanding, we propose a new functional grouping of planktonic protists in an ecophysiological context: (i) phagoheterotrophs lacking phototrophic capacity, (ii) photoautotrophs lacking phagotrophic capacity, (iii) constitutive mixotrophs (CMs) as phagotrophs with an inherent capacity for phototrophy, and (iv) non-constitutive mixotrophs (NCMs) that acquire their phototrophic capacity by ingesting specific (SNCM) or general non-specific (GNCM) prey. For the first time, we incorporate these functional groups within a foodweb structure and show, using model outputs, that there is scope for significant changes in trophic dynamics depending on the protist functional type description. Accordingly, to better reflect the role of mixotrophy, we recommend that as important tools for explanatory and predictive research, aquatic food-web and biogeochemical models need to redefine the protist groups within their frameworks. (C) 2016 The Authors. Published by Elsevier GmbH.
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| 4. |
- Mitra, Aditee, et al.
(författare)
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The role of mixotrophic protists in the biological carbon pump
- 2014
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 11, s. 995-1005
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Tidskriftsartikel (refereegranskat)abstract
- The traditional view of the planktonic foodweb describes consumption of inorganic nutrientsby photo-autotrophic phytoplankton, which in turn supports zooplankton and ultimately higher trophic levels. Pathways centred on bacteria provide mechanisms for nutrient recycling. This structure lies at the foundation of most models used to explore biogeochemical cycling, functioning of the biological pump, and the impact of climate change on these processes. We suggest an alternative paradigm, which sees the bulk of the base of this foodweb supported by protist plankton (phytoplankton and microzooplankton) communities that are mixotrophic – combining phototrophy and phagotrophy within a single cell. The photoautotrophic eukaryotic plankton and their heterotrophic microzooplankton grazers dominate only within immature environments (e.g., spring bloom in temperate systems). With their flexible nutrition, mixotrophic protists dominate in more mature systems (e.g., temperate summer, established eutrophic systems and oligotrophic systems); the more stable water columns suggested under climate change may also be expected to favour these mixotrophs. We explore how such a predominantlymixotrophic structure affects microbial trophic dynamics and the biological pump. The mixotroph dominated structure differs fundamentally in its flow of energy and nutrients, with a shortened and potentially more efficient chain from nutrient regeneration to primary production. Furthermore, mixotrophy enables a direct conduit for the support of primary production from bacterial production. We show how the exclusion of an explicit mixotrophic component in studies of the pelagic microbial communities leads to a failure to capture the true dynamics of the carbon flow. In order to prevent a misinterpretation of the full implications of climate change upon biogeochemical cyclingand the functioning of the biological pump, we recommend inclusion of multi-nutrient mixotroph models within ecosystem studies.
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| 5. |
- Nyström, Ingalill, 1969, et al.
(författare)
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FT-Raman Analyses of Blue Dyes Stuff Common in Swedish Folk Art from Hälsingland during 18th and 19th Century
- 2016
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Ingår i: Chemical Sciences Journal. - : OMICS Publishing Group. - 2150-3494. ; 7:2, s. 4-
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Tidskriftsartikel (refereegranskat)abstract
- The overall aim of this study is to gain a better understanding of the historic use of woad in Sweden in the18th and 19th centuries. A key question is, whether it is possible to distinguish between indigo from woad andexotic indigo using Raman spectroscopy? Reference samples prepared according to historic recipes using woad,exotic indigo, logwood and brazilwood - were used to dye different textile fibres - cotton, wool and linen. In addition,various reference compounds - indigotin, indirubin, kaempferol, luteolin, 3-hydroxyflavone and tryptanthrin - as wellas the ‘flower’ of the woad dye bath were analysed to identify specific fingerprint regions for each compound. Bluethreads from four historic textiles - a skirt and three rag balls - from the region of Hälsingland were then analysedin comparison to the references. A specific peak at 993 cm-1 was identified in the spectra taken from the flower ofthe woad vat, which we suggest possibly arises from 3-hydroxyflavone. DSA-ToF-MS analysis suggests flavoneglycosidesas possible candidates. However, cellulosic substrates show a broad vibration at 999 cm-1 overlappingthe flavone signature, thus rendering it non-diagnostic, but it might be possible to use this peak in Raman analysessupported by mass spectrometry to distinguish between indigo from woad and exotic indigo if the substrate is woolor if it is a pigment. Raman analyses of the historic samples identify the colourants as indigo and possibly woad andlogwod mixed with brazilwood.
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| 6. |
- Nyström, Ingalill, 1969, et al.
(författare)
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FT-Raman analyses of dyes and lac pigments in folk arts and crafts in the interiors of Decorative Farmhouses of Hälsingland, Sweden, UNESCO World Heritage
- 2015
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Ingår i: Book of abstracts. 8th International Conference on the Application of Raman spectroscopy in Art and Archaeology Wroclaw 1-5 September 2015, Polen.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This pilot study is about method development using FT-Raman supplemented with computational methods for analyzing dyes and lac pigments used in folk art and craft from Hälsingland, Sweden, during the 18th and 19th century. The study is part of an interdisciplinary four years long project funded by the Swedish Research Council (Vetenskapsrådet). Conservation scientists, chemists, physicists, conservators, art historians and ethnologists from different Swedish universities are collaborating to make a holistic approach and material characterization of wall paintings, painted wall-hangings, decorated wooden furniture and patterned textiles in Decorated Farmhouses of Hälsingland, UNESCO World Heritage since 2012. Spectroscopic methods combined with historic sources are used to understand the materials and the context and time when these artefacts were made. The interdisciplinary collaboration is essential and in this way, new and deeper knowledge of the paint, coatings, painting techniques and dyeing methods in the 18th and 19th century Swedish folk art and handicrafts can be obtained. The relevant research questions span over a wide range, for example about the existence and time frame of woad and turkish red dye. Suitable materials for characterization are for example clothing, which are often possible to date historically due embroidered monograms. Therefore, the material characterization of clothing dyes may shed light on the usage and distribution of various folk art techniques. In the pilot study we present different historic dyestuff such as safflower, cochineals, madder, turkish red, brazilwood, fustic, birch leaves, weld, turmeric, woad, indigo and indigo carmine - all common in Sweden during this period. The dye references were made according to old Swedish recipes. Different textile fibres - cotton, wool and linen/flax - were dyed. In addition various colouring matters - for example purpurin, alizarin, atranorin, orcein, myricetin, luteolin, quercetin, rhamnetin, emodin, crocin, curcummin, kaempferol, indigotin and indirubin - were tested to identify specific fingerprint regions for each dye. In order to assist the interpretation of the vibrational spectra of the samples, computational methods were performed. A typical case study is presented below: threads from an authentic textile, a blue skirt from early 19th century Delsbo parish, were analyzed using FT-Raman spectroscopy. The spectra were then compared with reference spectra. The Raman spectrum of a blue colored linen warp thread is shown together with the spectrum of pure indigotin as a reference (Figure 1). Preliminary results indicate that we are able to identify the main peaks as originating from indigotin in addition background from the linen fibre, suggesting indigo as the dye. Woad was also a common dye during the 18th and 19th century in Sweden [1]. Different from indigo, woad may also contain kaempferol. The comparison with reference spectra however did not yield a match in the fingerprint regions of kaempferol at f.ex. 1188 cm-1 and 1606 cm-1 [2, 3]. Therefore we may exclude woad as an ingredient in the colouring dye of this specific piece of clothing. Historic sources from 18th century usually mention woad as an additional ingredient in the indigo vat to catalyze and help the bacterial fermentation process [4, 5]. During 19th century though, woad is more seldom mentioned as an ingredient and perhaps this is an example of a more modern indigo vat. Other preliminary results shows that almost all pure colouring matters and some of the dyed textile fibres are easy to analyze with FT-Raman. However, it is difficult to analyse red dyes with this method. Furthermore, wool sometimes complicates the analyses. Therefore, we will continue using FT-Raman analyses and the computational models, supplemented with other analytical methods such as SERS and field-free APCI-TOF MS. References [1] Linders, J. Swenska Färge-konst: med Indlandske örter, gäs, blommor, blad, löf, barkar, rötter, wexter och mineraler. Stockholm: Johan Laur. Horrn, Kungliga Antiquit. Archivi Boktr., 1720. [2] Nyström, I. Bonadsmåleri under lupp: spektroskopiska analyser av färg och teknik i sydsvenska bonadsmålningar 1700-1870. Gothenburg Studies in Conservation 29. Göteborgs Universitet: Acta Universitatis Gothoburgensis, 2012. [3] Nyström, I. Spectroscopic analyses of artists' pigments and materials used in Southern Swedish painted wall hangings from the 18th and 19th centuries. Studies in Conservation. Maney, 2014. [4] Hurry, J. B. The woad plant and its dye. London: Oxford University Press, H. Milford (Repr. ed. Clifton New Jersey: Augustus M Kelley Pubs. june 1973), 1930. [5] Cardon, D. Natural dyes: sources, tradition, technology and science. London, Archetype, 2007. Acknowledgment This work is financially supported by the Swedish Research Council, Vetenskapsrådet.
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| 7. |
- Schön, Max Emil, et al.
(författare)
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Single cell genomics reveals plastid-lacking Picozoa are close relatives of red algae
- 2021
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The endosymbiotic origin of plastids from cyanobacteria gave eukaryotes photosynthetic capabilities and launched the diversification of countless forms of algae. These primary plastids are found in members of the eukaryotic supergroup Archaeplastida. All known archaeplastids still retain some form of primary plastids, which are widely assumed to have a single origin. Here, we used single-cell genomics from natural samples combined with phylogenomics to infer the evolutionary origin of the phylum Picozoa, a globally distributed but seemingly rare group of marine microbial heterotrophic eukaryotes. Strikingly, the analysis of 43 single-cell genomes shows that Picozoa belong to Archaeplastida, specifically related to red algae and the phagotrophic rhodelphids. These picozoan genomes support the hypothesis that Picozoa lack a plastid, and further reveal no evidence of an early cryptic endosymbiosis with cyanobacteria. These findings change our understanding of plastid evolution as they either represent the first complete plastid loss in a free-living taxon, or indicate that red algae and rhodelphids obtained their plastids independently of other archaeplastids.
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| 8. |
- Urrutia Cordero, Pablo, et al.
(författare)
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Phytoplankton diversity loss along a gradient of future warming and brownification in freshwater mesocosms
- 2017
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Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 62:11, s. 1869-1878
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Tidskriftsartikel (refereegranskat)abstract
- 1. Globally, freshwater ecosystems are warming at unprecedented rates and northern temperate lakes are simultaneously experiencing increased runoff of humic substances (brownification), with little known consequences for future conservation of biodiversity and ecosystem functioning.2. We employed an outdoor mesocosm experiment during spring and summer to investigate the combined effects of gradually increasing warming and brownification perturbations on the phytoplankton community structure (biodiversity and composition) and functioning (biomass).3. While we did not observe overall significant treatment effects on total phytoplankton biomasses, we show that predicted increases in warming and brownification can reduce biodiversity considerably, occasionally up to 90% of Shannon diversity estimates. Our results demonstrate that the loss of biodiversity is driven by the dominance of mixotrophic algae (Dinobryon and Cryptomonas), whereas several other phytoplankton taxa may be temporarily displaced from the community, including Cyclotella, Desmodesmus, Monoraphidium, Tetraedron, Nitzschia and Golenkinia.4. The observed loss of biodiversity coincided with an increase in bacterial production providing resources for potential mixotrophs along the gradient of warming and brownification. This coupling between bacterial production and mixotrophs was likely a major cause behind the competitive displacement of obligate phototrophs and supports evidence for the importance of consumer-prey dynamics in shaping environmental impacts on phytoplankton communities.5. We conclude that warming and brownification are likely to cause a profound loss of biodiversity by indirectly affecting competitive interactions among phytoplankton taxa. Importantly, our results did not show an abrupt loss of biodiversity; instead the reduction in taxa richness levelled off after exceeding a threshold of warming and brownification. These results exemplify the complex nonlinear responses of biodiversity to environmental perturbations and provide further insights for predicting biodiversity patterns to the future warming and brownification of freshwaters.
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| 9. |
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| 10. |
- Wilken, Susanne, 1983
(författare)
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Failure Mechanisms of Lithium-ion Battery Electrolytes: Detection and Mitigation
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The state-of-the-art electrolyte of the lithium-ion batteries (LIBs) present in most portable electronics contains the salt LiPF6 , organic solvents such as ethylene carbonate and dimethyl carbonate and a number of additives. This is true regardless of the exact active materials i.e. electrodes or cell design e.g. prismatic or pouch chosen. Despite LIB commercial success, these electrolytes suffer from poor chemical and thermal stability. As an example, elevated temperatures cause a decrease in battery performance attributed to electrolyte decomposition.The aim of this thesis was bothdetailed studies of the degradation of electrolytes, model systems as well as commercial, and discussions and verifications of suggested mitigation strategies - all based on a proper understanding at a molecular level.Various routes to electrolyte decomposition have been explored and elevated temperatures, impurities, and the electrochemical stability toward redox reactions at the electrolyte/electrode interfaces were suggested as main parameters affecting the electrolyte functionality. Using several different detection techniques, the electrolytes have been characterized with respect to their physical and safety related properties and analyzed by vibrational spectroscopy to track changes at the molecular level. Novel NMR and combined ab initio/TGA-FTIR strategies were employed to understand thermal decomposition.Mitigation strategies included the application of additives, in particular flame retardants, or a change in chemistry toward intrinsically more stable components, e.g. ionic liquids. Each additional component needed careful optimization in the electrolyte and trade-offs with performance decline were evaluated.The main conclusion was that if LIBs continue to use LiPF6 in organic solvents - material purity and thermal stability must be enhanced.
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