| 1. |
- Bergenudd, Helena, 1978-
(author)
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Understanding the mechanisms behind atom transfer radical polymerization : exploring the limit of control
- 2011
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Doctoral thesis (other academic/artistic)abstract
- Atom transfer radical polymerization (ATRP) is one of the most commonly employed techniques for controlled radical polymerization. ATRP has great potential for the development of new materials due to the ability to control molecular weight and polymer architecture. To fully utilize the potential of ATRP as polymerization technique, the mechanism and the dynamics of the ATRP equilibrium must be well understood. In this thesis, various aspects of the ATRP process are explored through both laboratory experiments and computer modeling. Solvent effects, the limit of control and the use of iron as the mediator have been investigated. It was shown for copper mediated ATRP that the redox properties of the mediator and the polymerization properties were significantly affected by the solvent. As expected, the apparent rate constant (kpapp) increased with increasing activity of the mediator, but an upper limit was reached, where after kpapp was practically independent of the mediator potential. The degree of control deteriorated as the limit was approached. In the simulations, which were based on the thermodynamic properties of the ATRP equilibrium, the same trend of increasing kpapp with increasing mediator activity was seen and a maximum was also reached. The simulation results could be used to describe the limit of control. The maximum equilibrium constant for controlled ATRP was correlated to the propagation rate constant, which enables the design of controlled ATRP systems. Using iron compounds instead of copper compounds as mediators in ATRP is attractive from environmental aspects. Two systems with iron were investigated. Firstly, iron/EDTA was investigated as mediator as its redox properties are within a suitable range for controlled ATRP. The polymerization of styrene was heterogeneous, where the rate limiting step is the adsorption of the dormant species to the mediator surface. The polymerizations were not controlled and it is possible that they had some cationic character. In the second iron system, the intention was to investigate how different ligands affect the properties of an ATRP system with iron. Due to competitive coordination of the solvent, DMF, the redox and polymerization properties were not significantly affected by the ligands. The differences between normal and reverse ATRP of MMA, such as the degree of control, were the result of different FeIII speciation in the two systems.
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| 2. |
- Claudino, Mauro
(author)
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Thiol−ene Coupling of Renewable Monomers : at the forefront of bio-based polymeric materials
- 2011
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Licentiate thesis (other academic/artistic)abstract
- Plant derived oils bear intrinsic double-bond functionality that can be utilized directly for the thiol–ene reaction. Although terminal unsaturations are far more reactive than internal ones, studies on the reversible addition of thiyl radicals to 1,2-disubstituted alkenes show that this is an important reaction. To investigate the thiol–ene coupling reaction involving these enes, stoichiometric mixtures of a trifunctional propionate thiol with monounsaturated fatty acid methyl esters (methyl oleate or methyl elaidate) supplemented with 2.0 wt.% Irgacure 184 were subjected to 365-nm UV-irradiation and the chemical changes monitored. Continuous (RT– FTIR) and discontinuous (NMR and FT–Raman) techniques were used to follow the progress of the reaction and reveal details of the products formed. Experimental results supported by numerical kinetic simulations of the system confirm the reaction mechanism showing a very fast cis/trans-isomerization of the alkene monomers (<1.0 min) when compared to the total disappearance of double-bonds, indicating that the rate-limiting step controlling the overall reaction is the hydrogen transfer from the thiol involved in the formation of final product. The loss of total unsaturations equals thiol consumption throughout the entire reaction; although product formation is strongly favoured directly from the trans-ene. This indicates that initial cis/trans-isomer structures affect the kinetics. High thiol–ene conversions could be easily obtained at reasonable rates without major influence of side-reactions demonstrating the suitability of this reaction for network forming purposes from 1,2-disubstituted alkenes. To further illustrate the validity of this concept in the formation of cross-linked thiol–ene films a series of globalide/caprolactone based copolyesters differing in degree of unsaturations along the backbone were photopolymerized in the melt with the same trithiol giving amorphous elastomeric materials with different thermal and viscoelastic properties. High thiol–ene conversions (>80%) were easily attained for all cases at reasonable reaction rates, while maintaining the cure behaviour and independent of functionality. Parallel chain-growth ene homopolymerization was considered negligible when compared with the main coupling route. However, the comonomer feed ratio had impact on the thermoset properties with high ene-density copolymers giving networks with higher glass transition temperature values (Tg) and a narrower distribution of cross-links than films with lower ene composition. The thiol–ene systems evaluated in this study serve as model example for the sustainable use of naturally-occurring 1,2-disubstituted alkenes at making semi-synthetic polymeric materials in high conversions with a range of properties in an environment-friendly way.
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| 3. |
- El Jamal, Sawsan
(author)
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Stability of Alternative Nuclear Fuel Materials in Aqueous Systems
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Nuclear power produces a large portion of the electricity worldwide. It has been the largest low-carbon energy source for more than 30 years and has played an essential role in the security of energy supplies for many countries. However, despite its advantages, its future is unknown mainly because of accidents that can happen under reactor operation and the high radioactivity of the fuel after use. Therefore, Generation IV nuclear power has been introduced as it promises a sustainable and economical way of producing energy and reduces some of the risks observed in current reactors. UC and UN have advantageous properties compared to conventional UO2-based fuel which makes them promising fuel candidates for Generation IV nuclear reactors. Even though the fuel for Generation IV reactors is planned to be reprocessed, unexpected political decisions may change these plans, and the used fuel could end up in a geological repository. Therefore, the behavior of these new fuel materials must be understood in accident scenarios in reactors as well as under deep geological repository conditions. The radioactivity of the used fuel will induce radiolysis of water that comes in contact with it. This will lead to oxidative dissolution of the fuel and this is one of the potential routes for radionuclide release in the environment.In the first part of this thesis, UC and UN have been investigated in aqueous solutions under anoxic conditions, and under the influence of external γ-radiation and H2O2, the latter mimicking the impact of α-radiolysis. The hydrolysis of these materials in aqueous systems resulted in matrix dissolution which is not observed for UO2. The oxidative dissolution induced by H2O2 is more prominent than hydrolysis in water with or without added HCO3- where higher concentrations of dissolved uranium can be detected. In addition, the differences in reactivity are discussed for these materials and H2O2 is most reactive towards UN followed by UC and finally UO2, yet the dissolution yield is the lowest for UN. The change in UC and UN behavior with consecutive exposure to H2O2 was attributed to a change in surface reactivity where catalytic decomposition of H2O2 becomes possible. As it was observed for H2O2 additions, radiation induced oxidative dissolution also dominates over hydrolysis. Unexpectedly high concentrations of H2O2 were observed in the irradiated systems. This was found to be due to formation of nano-particulate studtite that could not be separated from the solutions samples by filtration. Hence, it turned out to be impossible to determine the free U(VI) and H2O2 concentrations in these systems.Finally, the stability of pure and ZrN containing UN pellet fragments was investigated in aqueous system under external γ-radiation or H2O2 exposure. The behavior of these pellet fragments was similar to the UN powder where the dissolution of uranium was enhanced under oxidizing conditions if compared with anoxic conditions (hydrolysis). Consecutive exposures of UN pellet fragments to H2O2 showed a change in surface reactivity. This change is attributed to the formation of an oxide layer on the surface of UN, as UO2 is less reactive towards H2O2 and UO2 pellets display lower dissolution yields than UN pellets. In addition, the impact of ZrN as a stabilizing additive to UN pellets was studied. The addition of ZrN to UN is expected to stabilize the UN matrix and thus render a more accident tolerant fuel. Interestingly, it was shown that under oxidizing conditions, ZrN did not have a significant impact on the stability of UN pellets in aqueous systems
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| 4. |
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| 5. |
- Niemeyer Hultstrand, Jenny, 1990-
(author)
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Before Being Born : Studies on Preconception Health and Unplanned Pregnancies in Low- and High-Income Settings
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Nearly half of all pregnancies globally are unplanned. They represent a failure to meet individuals’ reproductive health needs and are associated with adverse maternal and child outcomes. Preconception and contraception care can help improving outcomes of pregnancies that are desired, and preventing those that are undesired. The aim of this thesis was to investigate factors that affect individuals and their children before they are born: parental preconception health and pregnancy planning. These phenomena were studied in Sweden and in Eswatini. Furthermore, a counseling tool to improve preconception care called the Reproductive Life Plan (RLP) was evaluated in Eswatini.In Sweden, baseline data from a cohort on pregnant women (n=3,389) of different origin were used. Many Nordic-born women drank alcohol (80% n=2,400) and smoked (20% n=607) preconception. Women born outside Europe were less likely to have these habits but more likely to have an unplanned pregnancy compared with Nordic-born women (AOR 1.37; 95% CI 1.01, 1.88).In Eswatini, data from client records were used (n=1,436). Seven out of ten pregnancies were unplanned (789/1,124). Adolescents had more than two-fold increased odds of unplanned pregnancy compared with women aged 20 or older (AOR 2.39; 95% CI 1.53, 3.75). Women with unplanned pregnancies were less likely to attend antenatal care (AOR 0.68; 95% CI 0.49, 0.95). We collected qualitative data on unplanned pregnancy using focus groups discussions (n=3) with health workers called mentor mothers (n=29). Unplanned pregnancies were thoroughly perceived as negative events with major social and health implications. Driven by poor socioeconomic conditions, young women often engaged in sexual relationships characterized by violence and gender inequality, resulting in unplanned pregnancies. These pregnancies often resulted in neglected children growing up to become vulnerable adolescents at risk of becoming pregnant unintendedly, thus generating a perpetuating cycle of unplanned childbearing.The RLP was used by the mentor mothers in client counseling (n=29). Focus groups discussions (n=7) and a questionnaire were used to collect data. The mentor mothers were key persons in implementing the RLP. Using this tool, they observed progress in pregnancy planning among their clients and thought it improved quality of contraceptive care. The clients' ability to form and achieve their reproductive goals was hindered by contextual factors such as intimate partner violence and limited reproductive health and rights.
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| 6. |
- Urbanaviciute, Indre, 1990-
(author)
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Multifunctional Supramolecular Organic Ferroelectrics
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Ferroelectric materials are known and valued for their multifunctionality arising from the possibility to perturb the remnant ferroelectric polarization by electric field, temperature and/or mechanical stimuli. While inorganic ferroelectrics dominate the current market, their organic counterparts may provide highly desired properties like eco-friendliness, easy processability and flexibility, concomitantly opening unique opportunities to combine multiple functionalities into a single compound that facilitates unprecedented device concepts and designs. Supramolecular organic ferroelectrics of columnar discotic type, that are the topic of this thesis, offer additional advantages related to their strong hierarchical self-assembly and easy tunability by molecular structure modifications, allowing optimization of ferroelectric characteristics and their hybridization with, e.g., semiconductivity. This not only leads to textbook ferroelectric materials that can be used as model systems to understand the general behaviour of ferroics, but also gives rise to previously unobserved effects stemming from the interplay of different functionalities.The core-shell structure of the molecules under the scope enables multiple pathways forrational design by molecular structure modification. This was firstly pursued via peripheral tail engineering on an archetypal self-assembling ferroelectric trialkylbenzene-1,3,5-tricarboxamide (BTA). We found that by shortening the alkyl chain length all the ferroelectric properties can be continuously tuned. In particular, changing the tail from C18H37 to C6H13causes an increase in depolarization activation energy (~0.8 eV to ~1.55 eV), coercive field(~25 V/μm to ~50 V/μm) and remnant polarization (~20 mC/m2 to ~60 mC/m2). The combination of the mentioned characteristics resulted in a record polarization retention time of close to 3 months at room temperature for capacitor devices of the material having the shortest alkyl chain – BTA-C6, which at the time of writing was one of the best results for liquid-crystalline ferroelectrics.Taking one step further, we experimentally demonstrated how introduction of branched-tailsubstituents results in materials with a wide operating temperature range and a data retention time of more than 10 years in thin-film solution-processed capacitor devices already atelevated temperatures with no measurable depolarization at room temperature. The observed differences between linear- and branched-tail compounds were analysed using density functional theory (DFT) and molecular dynamics (MD) simulations. We concluded that morphological factors like improved packing quality and reduced disorder, rather than electrostatic interactions or intra/inter-columnar steric hindrance, underlay the superior properties of the branched-tailed BTAs. Synergistic effects upon blending of compounds with branched and linear sidechains were shown to further improve the materials’ characteristics.Exploiting the excellent ferroelectric performance and the well-defined nanostructure of BTAs, we experimentally determined the Preisach (hysteron) distribution of BTA and confronted it to the one obtained for the semi-crystalline P(VDF:TrFE). This allowed to elucidate how the broadening of the Preisach distribution relates to the materials’ morphology. We further connected the experimental Preisach distribution to the corresponding microscopic switching kinetics. We argue that the combination of the two underlays the macroscopic dispersive switching kinetics as commonly observed for practical ferroelectrics. These insights lead to guidelines for further advancement of ferroelectric materials both for conventional and multi-bit data storage applications.Although having strong differences in the Preisach distribution, BTA and P(VDF:TrFE) both demonstrate negative piezoelectricity – a rare anomalous phenomenon which is characteristic to two-phased materials and has never been observed in small-molecular ferroelectrics. We measured a pronounced negative piezoelectric effect in a whole family of BTAs and revealed its tunability by mesogenic tail substitution and structural disorder. While the large- and small-signal strain in highly ordered thin-film BTA capacitor devices are dominated by intrinsic contributions and originates from piezostriction, rising disorder introduces additional extrinsic factors that boost the large-signal d33 up to −20 pm/V in short-tailed molecules. Interestingly, homologues with longer mesogenic tails show a large-signal electromechanical response that is dominated by the quadratic Maxwell strain with significant mechanical softening upon polarization switching, whereas the small-signal strain remains piezostrictive. Molecular dynamics and DFT calculations both predict a positive d33 for defect-free BTA stacks. Hence, the measured negative macroscopic d33 is attributed to the presence of structural defects that enable the dimensional effect to dominate the piezoelectric response of BTA thin films.The true multifunctionality of supramolecular discotics manifests when large semiconducting cores surrounded by field-switchable strongly polar moieties are introduced in the structure. We showed how the combination of switchable dipolar side groups and the semiconducting core of the newly synthetized C3-symmetric benzotristhiophene molecule (BTTTA) leads to an ordered columnar material showing continuous tunability from injection- to bulk-limited conductivity modulation. Both these resistive switching mechanisms may lead to the next-generation high-density non-volatile rewritable memory devices with high on/off ratios and non-destructive data readout – the element that has been desperately sought after to enablefully organic flexible electronics.
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| 7. |
- Björkbacka, Åsa, 1983-
(author)
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Radiation induced corrosion of copper
- 2015
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Doctoral thesis (other academic/artistic)abstract
- The process of radiation induced corrosion of copper is not well understood. The most obvious situation where the knowledge of this process is crucial is in a deep repository for high level spent nuclear fuel where the fuel will be sealed inside copper canisters. The radiation will penetrate the canisters and be absorbed by the surrounding environment. In this study gamma irradiations of polished and pre-oxidized copper cubes in anoxic pure water, air of 60-100 % RH and in humid argon were performed. The copper surfaces were examined using IRAS, XPS, cathodic reduction, SEM, AFM, and Raman spectroscopy. The concentration of copper in the reaction solutions was measured using ICP-OES. Also the formation of oxidative species caused by radiation absorption of water was studied by numerical simulations using MAKSIMA software. The corrosion of copper during gamma irradiation vastly exceeds what is expected. The production of oxidative species caused by radiation absorption of water is hundreds of times too low to explain the amount of oxidized copper. A possible explanation for this mismatch is an enhanced radiation chemical yield of HO· on the copper surface. Another one is an increased surface area due to oxidation of copper. One speculation is that HO· interacting with the copper oxide can cause oxidation of the metal. If the thermodynamic driving force is large enough then electrons can be conducted from the metal through the oxide to the oxidant. A dramatic increase in surface area together with an increased interfacial yield of HO· might explain the radiation enhanced corrosion process.
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| 8. |
- Deland, Mats, 1961-
(author)
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The Social City : Middle-way approaches to housing and sub-urban golvernmentality in southern Stockholm, 1900-1945
- 2001
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Doctoral thesis (other academic/artistic)abstract
- This dissertation deals with the period bridging the era of extreme housing shortages in Stockholm on the eve of industrialisation and the much admired programmes of housing provision that followed after the second world war, when Stockholm district Vällingby became an example for underground railway-serviced ”new towns”. It is argued that important changes were made in the housing and town planning policy in Stockholm in this period that paved the way for the successful ensuing period. Foremost among these changes was the uniquely developed practice of municipal leaseholding with the help of site leasehold rights (Erbbaurecht).The study is informed by recent developments in Foucauldian social research, which go under the heading ’governmentality’. Developments within urban planning are understood as different solutions to the problem of urban order. To a large extent, urban and housing policies changed during the period from direct interventions into the lives of inhabitants connected to a liberal understanding of housing provision, to the building of a disciplinary city, and the conduct of ’governmental’ power, building on increased activity on behalf of the local state to provide housing and the integration and co-operation of large collectives. Municipal leaseholding was a fundamental means for the implementation of this policy.When the new policies were introduced, they were limited to the outer parts of the city and administered by special administrative bodies. This administrative and spatial separation was largely upheld throughout the period, and represented as the parallel building of a ’social’ outer city, while things in the inner ’mercantile’ city proceeded more or less as before. This separation was founded in a radical difference in land holding policy: while sites in the inner city were privatised and sold at market values, land in the outer city was mostly leasehold land, distributed according to administrative – and thus politically decided – priorities.These differences were also understood and acknowledged by the inhabitants. Thorough studies of the local press and the organisational life of the southern parts of the outer city reveals that the local identity was tightly connected with the representations connected to the different land holding systems. Inhabitants in the south-western parts of the city, which in this period was still largely built on private sites, displayed a spatial understanding built on the contradictions between centre and periphery. The inhabitants living on leaseholding sites, however, showed a clear understanding of their position as members of model communities, tightly connected to the policy of the municipal administration. The organisations on leaseholding sites also displayed a deep co-operation with the administration. As the analyses of election results show, the inhabitants also seemed to have felt a greater degree of integration with the society at large, than people living in other parts of the city. The leaseholding system in Stockholm has persisted until today and has been one of the strongest in the world, although the local neo-liberal politicians are currently disposing it off.
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| 9. |
- Jonsson, Sofia, 1973-
(author)
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The influence of soil and contaminant properties on the efficiency of physical and chemical soil remediation methods
- 2009
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Doctoral thesis (other academic/artistic)abstract
- A vast number of sites that have been contaminated by industrial activities have been identified worldwide. Many such sites now pose serious risks to humans and the environment. Given the large number of contaminated sites there is a great need for efficient, cost-effective remediation methods. Extensive research has therefore been focused on the development of such methods. However, the remediation of old industrial sites is challenging, for several reasons. One major problem is that organic contaminants become increasingly strongly sequestered as they persist in the soil matrix for a long period of time. This process is often referred to as ‘aging’, and leads to decreasing availability of the contaminants, which also affects the remediation efficiency. In the work underlying this thesis, the influence of soil and contaminant properties on the efficiency of various physical and chemical soil remediation methods was investigated. The investigated contaminants were polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). Briefly, the results show that as the size of soil particles decreases the contaminants become more strongly sorbed to the soil’s matrix, probably due to the accompanying increases in specific surface area. This affected the efficiency of the removal of organic pollutants by both a process based on solvent washing and processes based on chemical oxidation. The sorption strength is also affected by the hydrophobicity of the contaminants. However, for a number of the investigated PAHs their chemical reactivity was found to be of greater importance for the degradation efficiency. Further, the organic content of a soil is often regarded as the most important soil parameter for adsorption of hydrophobic compounds. In these studies the effect of this parameter was found to be particularly pronounced for the oxidation of low molecular weight PAHs, but larger PAHs were strongly adsorbed even at low levels of organic matter. However, for these PAHs the degradation efficiency was positively correlated to the amount of degraded organic matter, probably due to the organic matter being oxidized to smaller and less hydrophobic forms. The amount of organic matter in the soil had little effect on the removal efficiency obtained by the solvent-washing process. However, it had strong influence on the performance of a subsequent, granular activated carbon-based post-treatment of the washing liquid. In conclusion, the results in this thesis show that remediation of contaminated soils is a complex process, the efficiency of which will be affected by the soil matrix as well as the properties of the contaminants present at the site. However, by acquiring thorough knowledge of the parameters affecting the treatability of a soil it is possible to select appropriate remediation methods, and optimize them in terms of both remediation efficiency and costs for site- and contaminant-specific applications.
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| 10. |
- Kilger, Magnus, 1974-
(author)
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Talking talent : Narratives of youth sports selection
- 2017
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Doctoral thesis (other academic/artistic)abstract
- In sports, there seems to be an eternal interest in discovering young talents and refining them into elite adult athletes. The dilemma of selecting talent, while at the same time ensuring every child´s right to participate, needs to be addressed and have consequences in social practice. This dissertation elucidates the discourse of selection and the process of selecting young sporting talents during final selection camps for youth national teams in football, hockey and floorball in Sweden. More specifically, the aim is to analyze how talent selection is organizationally legitimized, how “selectability” is produced in interaction and how specific narratives are used in success-stories. The empirical material includes research interviews, performance appraisal interviews (between district or national team coaches and the player) and field studies during ongoing final selection camp. Drawing on a discursive-narrative approach, the aim is to investigate how selection is discursively legitimized and, by using narrative analysis, how positioning in talk-in-interaction functions.The first article investigates the construction of legitimate selection within the Swedish Sports Confederation by analyzing their organizational documents, sport journals and literature for coach education. The findings show how a specific set of narratives are used to legitimize selection and how legitimacy works both individually to those within the selection system and on a wider arena of welfare politics. The second article investigates the co-construction of selectability in small story-interaction during interviews between the coach and a player in the final selection camp. The analyses highlight how this narrative genre produces certain stories and preferred positions. The third article analyzes how the young participants, in research interviews during final selection camp, uses discursively shared narratives to produce personal stories of success. The findings illustrate how the personal stories of success are balancing the dilemmatic space, positioning yourself as outstanding and at the same time appear a humble team player.The principal contribution of this dissertation is to show how talent is organizationally legitimized and how selectability is produced in interaction, as well as illustrate how specific stories are used in stories of success. This work investigates the discursive framework for selection and how rationalities for talent selection are produced (and reproduced) and co-constructed in narrative interaction. In this apparatus of selection it takes more than physical talent to be chosen; it takes talking talent.
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