| 481. |
- Tsiligiannis, Epameinondas
(författare)
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Nitrogen-containing products from atmospheric oxidation of volatile organic compounds
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atmospheric oxidation of volatile organic compounds (VOC) produces a wide range of oxygenated organic products that lead to formation of secondary organic aerosol (SOA). SOA represents a significant fraction of the tropospheric aerosol that influence climate and human health. However, the level of understanding of SOA processes is low compared to other aerosol processes and one reason is the complexity of VOC oxidation under various conditions. VOC oxidation under high NOx conditions or by nitrate radicals (NO3) leads to formation of various nitrogen-containing compounds. The N-containing products, apart from contributing to SOA formation, can act as NOx reservoir and/or as permanent sink affecting ozone formation. Also, organic nitrogen can play a role on the atmospheric nitrogen cycle, with ecological impacts. In this work the focus is on the nitrogen-containing oxidation products in the gas phase and their contribution to the particle phase. Laboratory studies on OH-initiated oxidation of 1,3,5- trimethylbenzene (TMB) (an anthropogenic VOC) under different NOx levels and NO3-initiated oxidation of isoprene (the most abundant non-methane biogenic VOC) were conducted utilizing the Go:PAM flow reactor and the atmospheric simulation chamber SAPHIR. The oxidation products from these reactions were detected using chemical ionization mass spectrometry. This method was also applied in the field to measure selected organonitrates related to the laboratory studies. The TMB oxidation under elevated NOx conditions favored the formation of organonitrates (ONs) reducing the amount of highly oxygenated organic molecules (HOM) monomers and especially the dimers, leading to suppression of new particle formation. Ambient observations of nitro-aromatic compounds originating from anthropogenic sources demonstrated that nitrophenol and its analogue can be used as direct tracers of primary emissions from biomass burning. NO3 oxidation of isoprene produced monomers and dimers with 1 to 3 nitrate groups. The specifics of the various time evolutions indicating formation pathways from multi-generation secondary chemistry. Selected products from this secondary chemistry had high propensity to participate to the particle phase. Observations from six locations around the globe showed that the isoprene-derived ONs with chemical formula C4H7NO5 observed in the laboratory did dominate the ambient gas phase product distribution both during nighttime and daytime. To summarize, the objectives of this thesis are to advance our understanding on the nitrogen-containing products from atmospheric oxidation of different VOC, identify their reaction mechanisms and product distributions, and provide insights on their role to SOA formation.
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| 482. |
- Tornberg, Marcus
(författare)
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Dynamics of a Droplet that Assists III-V Nanowire Growth
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Control of the process of crystal growth has for decades been achieved by addressing the growth temperature and material supply of the growth species. Directional control of both crystal growth and etching has, for example, been achieved by utilizing a liquid droplet to assist the process. This is a common approach to achieve crystal growth of nanostructures, as in the case of Au-assisted III-V semiconductor nanowires. Although controlled droplet-assisted growth has been studied in depth, less attention has been given to the droplet composition and how it dynamically interacts with the nanowire. This thesis explores the fundamental limits for one-directional droplet-assisted crystal growth. This is studied first by intentionally displacing the droplet from the facet at which it originally assisted the crystal growth. The process and cause for displacement is studied for Au-assisted GaAs and InAs nanowires by combining experimental observations and theoretical modeling of the droplet wetting. In addition, it is shown that the final position of the droplet can be controlled by tailoring the surfaces of the nanowire, which in turn is used for design of branched structures. Furthermore, this thesis focuses on the droplet dynamics and the formation of a truncation at the droplet-nanowire interface, as the geometry of the droplet wetting of the top facet approaches the fundamental limit. The studies of this thesis are conducted using metal-organic chemical vapor deposition (MOCVD), both in- and outside an environmental transmission electron microscope (ETEM). Ex-situ analysis of droplet displacement allows us to investigate the statistics of the process, to understand trends of the droplet wetting. On the other hand, performing MOCVD inside an ETEM enables real-time studies of the dynamic processes during growth, such as observations of the droplet wetting angle or the facet truncation. Using a combination of theoretical modeling, high-temperature X-ray energy dispersive spectroscopy and direct imaging during growth, we measure and estimate the previously inaccessible gallium and arsenic concentration in the droplet, as well as the surface energies of the Au-Ga droplet and the GaAs nanowire sidewalls. These findings could in turn be used to further improve our understanding of the atomic arrangement at the crystal surfaces and interfaces during growth. Such an understanding could lead to improved control and design of crystal nanostructures.
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| 483. |
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| 484. |
- Zale, Rolf, 1954-
(författare)
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Lake sediments around the Antarctic Peninsula : archives of climatic and environmental changes
- 1993
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lakes and lake sediments from four areas around the Antarctic Peninsula are described.The concentrations of trace metals in sediment are found to be a useful tool in distinguishing between the different sedimentary phases during a transition from marine to limnic environment.A tephrochronology based on Deception Island tephra is developed, and used to cross date sediments from different lakes in order to overcome the radiocarbon dating problem of the area.The fluctuating concentrations of copper and phosphorus from penguin guano in the sediment of Lake Boeckella are used as a proxy for the penguin inpact on the sediment, and the size of the penguin rookery on the shores of the lake. Anthropogenic activities in the area, as well as climatic changes are discussed in relation to the rookery size.A radiocarbon dating model developed for the sediment of Lake Boeckella showed that the radiocarbon correction factor in the sediment depends on the amount and apparent age of the penguin guano washed down into the lake, and the amount of particulate carbon from the watershed present in the sediment. Neither the "old" meltwater from the glaciers nor dissolved carbonates contributes significantly to the correction factor. The model is used to achieve more accurate radiocarbon dates of the Lake Boeckella sediment. This model, or a modified version, may contribute to a higher dating accuracy and a better understanding of the dating problems in Antarctica.Deglaciation dates, as well as data on the climatic and environmental history of Byers Peninsula on Livingston Island, South Shetland Islands, of Hope Bay, Antarctic Peninsula and of Hidden Lake area, James Ross Island are given.
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| 485. |
- Hynynen, Jonna, et al.
(författare)
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Investigation of extinguishing water and combustion gases from vehicle fires
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sales of electric vehicles doubled in 2021 compared to the previous year and nearly 10% of the global new-car sales were electric in 2021. In the recent IEA Global EV Outlook 2022, Norway, Iceland, and Sweden were reported to have the highest electric car shares of the new car market: 86%, 72% and 43%, respectively. Electrification of transport has multiple benefits but has also raised some concerns. For example, the use of rare metals and their sourcing are concerns from an environmental perspective, the capacity of the electricity network and the limited number of charging stations has been raised as an implementation barrier, and the new fire and explosion risks of batteries have caused concerns amongst users, property owners and rescue services alike society.Fires starting in the traction batteries (lithium-ion battery) are rare but if the battery catches fire, it can be difficult to extinguish since the battery packs are generally well protected and difficult to reach. To cool the battery cells, firefighters must prolong the application duration of suppression agent. This generally results in use of large amounts of water/fire extinguishing agent, which could carry pollutants into the environment.In this work, extinguishing water from three vehicle fires as well as from one battery pack fire has been investigated. Large-scale fire tests were performed with both conventional and electric vehicles. Tests were performed indoors at RISE, Borås, which also allowed analysis of combustion gases for both inorganic and organic pollutants in the gas and liquid phase.It was found that nickel, cobalt, lithium, manganese and hydrogen fluoride appeared in higher concentrations in the effluents from the battery electric vehicle and lithium-ion battery compared to from the internal combustion engine vehicle. However, lead was found in higher concentrations in the effluents from the internal combustion engine vehicle, both in the combustion gases as well as in the extinguishing water. Ecotoxicity analysis showed that extinguishing water from all vehicle and battery fires analysed in this work were toxic against the tested aquatic species.
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| 486. |
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| 487. |
- Kjellman, Johan, 1961-
(författare)
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ABC2O8 : a new look on the crystal chemistry and classification of samarskite group minerals
- 2017
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Ingår i: PEG2017 8th International Symposium on Granitic Pegmatites. - 9788283470192 ; , s. 64-67
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this paper is to present, based on the collective database of Electron MicroProbe Analyses (EMPA) of Samarskite Group Minerals (SGM), crystal chemical evidence for an ordered formula – ABC2O8 – and the need for a redefinition of the mineral group.
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| 488. |
- Ogenhall, Erik, 1967-, et al.
(författare)
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Deformation history of the Palaeoproterozoic Svecofennian supracrustal rocks at Hamrånge, south-central Sweden
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The west-central part of the Palaeoproterzoic Fennoscandian Shield consists of different lithological units: the marine Bothnian basin, granitoids formed in an active continental margin (the Ljusdal Domain, LjD), and a continental back-arc magmatic region (the Bergslagen province). Geochemical signatures indicate that the supracrustal Hamrånge Group (HG) represents an additional unit - a fragment of an oceanic island arc that has been accreted to the continental margin granitoids. Structural data show that the 1.9 Ga supracrustal rocks in the lower part of the stratigraphy of the HG have been affected by three episodes of deformation (D1-D3). On the other hand, the ≤1.86 Ga quartzite in the uppermost part probably has been affected only by the latter two deformational phases. The nature of D1 is poorly understood, but may represent the early accretion of the island arc to the continental margin. A NW-SE compressional phase during D2 resulted in F2-folds and thrusts in the supracrustal rocks, and thrusts are also observed in the footwall granitoids. Microstructures demonstrate that metamorphism outlasted and possibly peaked after D2, and structural data imply a period of flattening subsequent to the D2-thrusting, but prior to D3. During D3 the area was affected by a regional N-S compression causing upright E-plunging F3-folding. This F3-folding matured to steep ductile shear zones, which belong to a system of 1.82-1.80 Ga NW-SE shear zones transecting the central part of the Fennoscandian Shield. The structural evolution recorded in the Hamrånge area, suggesting D2-thrusting towards NW and subsequent N-S (D3) shortening, is in accordance with the accepted tectonic models of the Fennoscandian Shield. The structural configuration of the area is partly comparable, at a smaller scale, to a major tectonic unit in the 0.5 Ga Scandinavian Caledonides, the Lower Seve Nappe (LSN), suggesting similarities in structural evolution of orogenies through time. An important difference is the relative timing of deformation and metamorphism. However, significant differences in tectonostratigraphy suggest that the HG is not far-transported and that the HG and tectonically underlying granitoids of the LjD originally had a close spatial relationship.
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| 489. |
- Ogenhall, Erik, 1967-
(författare)
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Geological Evolution of the Supracrustal Palaeoproterozoic Hamrånge Group: A Svecofennian Case Study
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The work presented in this thesis utilizes several geological methods to investigate the origin and evolution of the supracrustal rocks in the Palaeoproterozoic Hamrånge Group (HG) in the south-central Swedish Svecofennian. The first paper is based on whole-rock geochemistry to show the plate tectonic setting of volcanic rocks within the HG. This indicates that the environment was probably an oceanic volcanic arc. Geochronology, used in paper two, shows that the volcanism was active at 1888±6 Ma and that the sediments forming the stratigraphically overlying quartzite were deposited after 1855±10 Ma, with provenance ages overlapping both the volcanic rocks and the 1.86-1.84 Ga continental margin Ljusdal granitoids. In the third paper, thermobarometry was applied to samples from the HG, the migmatitic Ockelbo sub-domain to the south, and the 1.81 Ga Hagsta Gneiss Zone (HGZ) that separate these two units. The results show distinct differences in the metamorphic conditions that have affected the HG and the Ockelbo sub-domain, supporting previous interpretations that the HGZ is an important crustal structure, possibly a terrane or domain boundary. Paper four deals with the structural geology of the Hamrånge area. The study shows that the volcanic rocks and the underlying mica schist have been subjected to three deformation episodes (D1-D3), while the uppermost quartzite was most likely only affected by D2 and D3. While structures related to D1 are rarely seen, D2 resulted in a penetrative foliation, strong lineations and NW-vergent folding and thrusting. D3 is a result of a N-S compression that formed regional E-W folds and steep, ca. NW-SE shear zones, e.g. the HGZ. The results presented in this thesis, integrated with previously published data, outline a model for the geological evolution of the Hamrånge area: At 1.89 Ga a volcanic arc formed that subsequently collided with a continental margin resulting in the first deformation episode, D1, and probably a metamorphic event. This was possibly followed by an extensional period, after 1855±10 Ma, forming a basin that accumulated sediments later to form the quartzite stratigraphically on top of the volcanic rocks. The second deformation episode, D2, formed a fold-thrust belt when the supracrustal HG was thrusted to the NW, on top of the 1.86-1-84 Ga Ljusdal Domain. Flattening and a second metamorphic period followed this thickening of the crust. The last ductile deformation, D3, caused by regional tectonic forces, resulted in F3-folds that matured into ca. 1.8 Ga large-scale, steep shear zones transecting the Fennoscandian Shield.
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| 490. |
- Balksten, Kristin, et al.
(författare)
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The influence of particle size and structure in hydrated lime on the properties of the lime putty and lime mortar
- 2010
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Ingår i: International journal of architectural heritage. - Philadelphia : Taylor & Francis. - 1558-3058 .- 1558-3066. ; 4:2, s. 86-101
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this work, scanning electron microscopy (SEM) analysis of lime slaked in different ways and analysis of thin section of lime putty and mortar specimens by light microscopy was combined with practical tests and field studies to evaluate the impact of the slaking technique on the properties of the lime putty as well as the structure of the fresh and carbonated mortar. The lime slaking methods studied were wet slaking and earth slaking, giving lime putties with very different consistency and workability. The aim of this work was to use microscopy techniques to explain these differences in properties and to investigate if it is possible to use these analytical methods to recognize the lime-slaking technique used in a historical lime mortar. The results obtained by SEM show significant differences in structure between the lime putties. The earth-slaked lime consists of relatively large particles that are packed in a porous system compared with the wet-slaked lime with very small particles closely packed in a dense structure. After storing, the wet-slaked lime gives a putty that has a dense and clearly defined stratified structure, whereas the earth-slaked lime is porous and has no stratification.
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