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  • Public defence: 2018-02-28 10:00 KBE301 - Lilla Hörsalen, KBC-huset, Umeå
    Revoju, Srikanth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Molecular design, synthesis and performance evaluation of phenothiazine-based small molecules for efficient organic solar cells2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Photovoltaics offers one of the most promising routes to generate electricity in a clean way. As an emerging technology in photovoltaics, organic solar cells (OSC) have attracted a great deal of attention owing to their potential low-cost, lightweight, flexibility and solution processability. Although power conversion efficiencies above 12% have been achieved at this date, there is a great interest for new ideal materials to further improve the PCEs and address device durability, which are major concerns for the commercialization of this technology. The main objective of this thesis is to design and synthesize phenothiazine-based conjugate small molecules and explore their use as electron donor components in OSCs. Phenothiazine is a non-planar moiety with unusual “butterfly” type of geometry, which is known to reduce molecular aggregation and intermolecular excimer formation.

    In the first study of this thesis, a small molecule based on a cyano-arylenevinylene building block with deep HOMO level was prepared. Although a high open-circuit voltage of 1.0 V was achieved, the tendency of the small molecule to crystallize in the active layer at a higher temperature and with time hindered the attainment of an optimal phase morphology required for the achievement of a higher efficiency. In the second and third studies, phenothiazine was used as a π-system bridge and as a core unit to construct small molecules based on symmetric and asymmetric frameworks with varying terminal electron-withdrawing groups. The electron-withdrawing property of the terminal units was found to have a significant influence on the optical absorption properties, electronic energy levels, molecular ordering, charge carrier mobility and morphology of the resulting active layers. In the fourth study, side-chain modification of the phenothiazine unit of symmetrically configured small molecules with an oxygen-containing (methoxyethoxy ethyl) side chain resulted in the enhancement of the dielectric constant. Although absorption properties were unchanged in solution, a dense π-π stacking was observed in the solid state.

    In summary, it is demonstrated that phenothiazine is a promising candidate and worth exploring donor material for OSCs. Its versatility as a π-linker and as a central core unit in symmetric and asymmetric configurations has been explored. The use of nonplanar building blocks such as phenothiazine for the construction of donor materials is an interesting strategy for controlling molecular aggregation and difficult solution processability of small molecules if it is combined with a judiciously designed conjugate backbone.

  • Public defence: 2018-03-02 09:00 E04, Farmakologihuset, Umeå
    Tomic, Katarina
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Urology and Andrology.
    Data quality in the National Prostate Cancer Register (NPCR) of Sweden2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Data in quality registers are increasingly used for quality assurance of health care, benchmarking, and research. If valid conclusions are to be drawn from such studies, it is vital that register data have high quality. The aim of this thesis was to assess data quality in the National Prostate Cancer Register (NPCR) of Sweden, a nationwide register that since 1998 captures 98% of all cases of Prostate cancer (Pca) in Sweden. The proportion and characteristics of Pca cases not registered in NPCR was investigated in paper I. Four dimensions of data quality were evaluated for NPCR in paper II: completeness, timeliness, comparability, and validity. Proportion and characteristics of Pca cases registered in NPCR but with unknown risk category were investigated in paper III. Finally, the association between Socioeconomic Status (SES) and Pca diagnosis, treatment, and mortality was studied in paper IV. 

    Material and methods: Data quality of NPCR was studied by cross-linkages between NPCR and other health care registers and demographical databases by use of the Swedish personal identity number. Validity was further studied by re-abstraction of patient health care records, followed by comparison of re-abstracted and original register data.

    Results: Men not registered in NPCR, who constituted around 2% of all cases in the Swedish Cancer Register, differed only modestly in characteristics from cases in NPCR, indicating that NPCR is generalizable for all men with Pca in Sweden. Data quality in NPCR was high overall, with high completeness compared to the Swedish Cancer Register with registration mandated by law and few Pca cases were detected by use of death certificates. There was timely registration, and good comparability with registration forms and coding routines that were compliant with international guidelines. Data validity was high with high agreement and correlation for key variables. Men with unknown risk category had, compared to men with known risk category, more often concomitant bladder cancer, higher comorbidity, and lower Pca mortality. Men with high SES had, compared to men with low SES, higher probability of Pca detected during health checkup, shorter waiting times for prostatectomy, and higher probability of curative treatment for intermediate and high-risk cancer. Pca mortality was lower in men with high SES than in men with low SES for high-risk cancer.

    Conclusion: These results indicate that data quality in NPCR is high and that NPCR is population-based. There were consistent differences in diagnostic and therapeutic activity according to SES despite an equal access tax-financed healthcare system in Sweden. 

  • Public defence: 2018-03-02 10:00 KB.E3.03 (Stora hörsalen, Carl Kempe-salen), Umeå
    Veenaas, Cathrin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Developing tools for non-target analysis and digital archiving of organic urban water pollutants2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes efforts to develop robust methods for the creation and use of digital archives of environmental samples, and proposes guidelines based on the results. Digital archives are repositories that store environmental samples digitally. Traditionally, samples are stored physically in environmental specimen banks over long time periods. However, this has several drawbacks, for example degradation effects and limited accessibility. During the course of my PhD project I developed methods that allow the comprehensive analysis of sewage sludge samples. Sewage sludge is a complex matrix that contains many commercial chemicals. In addition, sewage treatment plants form a link between the human society that generates the sewage and the environment, making sewage sludge a very interesting matrix to analyze. The developed methods enable analysis and subsequent identification of compounds of all sizes and with diverse chemical characteristics. I further explain how unknown compounds can be identified (non-target screening) using mass spectral analysis and several other approaches (e.g. retention indices).

    The thesis is divided into three parts. In the first part, Data Generation, I describe the development of sample preparation methods for analyzing sewage sludge with gas chromatography (GC) and liquid chromatography (LC) coupled to high resolution mass spectrometry (HRMS). For the GC approach, two methods involving use of different extraction techniques, solvents, and matrix reduction techniques are presented while for the LC approach different extraction techniques are compared. The methods have been developed to enable the generation of data suitable for digital archiving. In the second part of the thesis, Data Evaluation, I present ways to find and identify compounds of interest. Firstly, time trend analyses provide a way to prioritize pollutants, for example by focusing on pollutants that are increasing with time. Thousands of compounds with significant time trends were detected and several hundred of them were tentatively identified. Compounds with strong increasing trends included, for example, UV-filters from sunscreens. Secondly, a new retention index system for comprehensive two‑dimensional chromatography (GC×GC) is introduced to characterize compounds in terms of their retention times in the second dimension. The new retention index system is based on co-injection of polyethylene glycols and was validated for various compounds of diverse classes. Thirdly, I tested different ways to predict GC×GC retention times or indices. Those methods include a multivariate prediction (PLS) approach using molecular descriptors, which proved to be the best approach, and use of commercially available software. The last part of my thesis, Data Archiving, discusses requirements to create digital archives and how they can be used. Here I present the current state and options for archiving data files, and give recommendations for each step, from sample collection, through instrumental analysis to storage of the final data.

  • Public defence: 2018-03-02 10:00 Hörsal E, Umeå
    Englund, Claire
    Umeå University, Faculty of Social Sciences, Department of Education. Centre for teaching and learning (UPL), Umeå University.
    Teaching in an age of complexity: exploring academic change and development in higher education2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Higher education (HE) has expanded and diversified at an unprecedented rate over the last two decades in response to a rapidly changing educational and political climate. Change and development are omnipresent, a constant part of university teachers’ sociocultural and organisational practice at multiple levels; the micro-level, the meso-level and the macro-level Against this background, the aim of this thesis is to gain a deeper understanding of the factors that influence academic change. A further aim of the thesis is to provide insight into factors that may be relevant in the design of academic development activities to support teachers and managers in the enhancement of teaching and learning. A twelve-year longitudinal study of teachers on an online pharmacy programme forms the basis for the research, where a multilevel approach is used to investigate academic change and development in a teaching and learning environment supported by educational technology (Edtech). The approach captures the influence of factors such as conceptions and approaches to teaching at the micro-level of the individual teacher, as well as the influence of systemic factors such as the sociocultural context at the meso-level of the department or programme and the structural context at the macro-level of the institution.

    To explore and understand the complexity of change and development in academic practice at micro-, meso- and macro-level two theoretical frameworks are used: conceptions of and approaches to teaching (CAT), and Cultural-Historical Activity Theory (CHAT). An interventionist method based on the tenets of CHAT was also employed. Data analysed in the thesis includes interviews with teachers (n=57), observations (n=27 hours), student evaluation surveys (n=30) and document analysis (n=11) collected over a 12-year timespan (2004-2016). The analysis indicated that at the micro-level a critical factor in the choice and use of Edtech is the underlying conception of and approach to teaching and learning of the teacher. Opportunities for change and development were found to be facilitated by the sociocultural context at the meso-level of the department, where support from the community and mediating tools for communication were present, but could also be hindered when this was lacking. At macro-level, institutional policy and strategy documents were seen to impede change and development, where research is consistently prioritised over teaching. At the meso-level of the department or programme, the opportunity to work together as a team to collaboratively construct and develop practice was found to be of significance in the development of agency and academic practice.

    Taking into account a combined analysis of the five papers included, it can be concluded that if a deeper understanding of academic change and development is to be achieved, it is necessary to adopt a holistic approach, considering factors at micro-, meso- and macro-level and the interrelationships between these factors. This thesis discusses the consequences of the research for the facilitation of academic change and development. A multilevel, holistic approach is suggested, building on the principles of the Scholarship of Teaching and Learning (SoTL) model. SoTL initiatives at all levels should be aligned to promote academic change and development through: the development of teachers’ individual practice at micro-level, the collaborative development of scholarly practice at the meso-level of the department and a strategic institutional approach at macro-level linking SoTL to employment and promotion frameworks and the recognition of teaching quality.

    The main contribution of this thesis lies in the adoption of a holistic approach to understanding academic practice in higher education, taking into consideration factors at micro-, meso- and macro-level and the interrelationships between these factors. 

  • Public defence: 2018-03-02 13:15 N430, Umeå
    Klechikov, Alexey
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Graphite oxides for preparation of graphene related materials: structure, chemical modification and hydrogen storage properties2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Carbon materials have been studied for hydrogen storage for decades, but they showed too low capacity at ambient temperature compared to target values for practical applications. This thesis includes two parts. First one is fundamental study of graphite oxides (GO) structure and properties. Second part is focused on hydrogen storage properties of graphene related materials prepared using GO as a precursor.

    We studied the effects of synthesis methods and oxidation degree on solvation/intercalation properties of GOs. New effect of temperature induced reversible delamination was observed for Hummers GO (HGO) immersed in liquid acetonitrile. Experiments with swelling of Brodie GO (BGO) in 1-octanol revealed parallel orientation of the intercalated solvent molecules relative to graphene oxide (GnO) layers. Chemical functionalization of GO in swelled state allowed us to synthesize the materials with subnanometer slit pores supported by molecular pillars. Structure and properties of pillared GO were characterized by variety of methods. Swelling properties of multilayered GnO membranes were compared to properties of precursor GO. GnO membranes were found to swell similarly to GO powders in some solvents and rather differently in other. Our experiments revealed important limitations in application of GO membranes for nanofiltration. Several parameters were found to affect the size of permeation “channels” provided by interlayers of GnO membrane structure: e.g. nature of solvent, pH of solutions and concentration of solutes.

    Hydrogen storage parameters were studied for a set of graphene related materials with broad range of surface areas (SSA) (200 - 3300 m2/g). Hydrogen sorption weight percent (wt%) is found to correlate with SSA for all studied graphene materials following the trend standard for other nanostructured carbon materials. The highest hydrogen uptakes of ~1.2 wt% at 296 K and ~7.5 wt% at 77 K were measured for graphene material with SSA of over 3000 m2/g. Addition of Pd and Pt nanoparticles to graphene materials did not resulted in improvement of hydrogen storage compared to nanoparticles-free samples. No deviation from the standard wt% vs. SSA trends was also observed for pillared GO materials. Therefore, hydrogen storage properties of graphene related materials at room temperatures are not confirmed to be exceptional. However, high surface area graphene materials are found to be among the best materials for physisorption of hydrogen at liquid nitrogen temperature. Moreover, hydrogen storage capacity of 4 wt%, comparable to target values, was observed at temperature of solid CO2 (193 K) which can be maintained using common refrigeration methods.

  • Public defence: 2018-03-09 10:00 Nbvh 1031, Umeå
    Nordvall, Olov
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Cognition in interned adolescents: aspects of executive functions and training2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This doctoral thesis examines adolescents with a history of antisocial behavior with a focus on investigating executive functioning, impulsivity and experiences of everyday executive problems. The thesis further investigates the associations between self-reported and performance-based measures. Finally, it investigates whether processed-based executive function training can influence trained and non-trained executive functions and related scholastic abilities.

    Antisocial behavior is a complex concept, associated with high costs of personal, interpersonal and societal nature. In general, people implement the majority of their life´s share of delinquent and antisocial behaviors around the adolescent years, as described by the so-called age-crime curve. This period is associated with rapid cognitive development, and deficits in this period of time have been associated with an increased susceptibility to partake in antisocial behavior. Also, larger impairments are associated with more severe behaviors. In many western countries, there exist a duality of both welfare and judicial considerations in the case of antisocial individuals who are minors. As compared to adults, persons under the age of criminal responsibility typically face a different combination of rehabilitative and penal consequences from maladaptive, delinquent or antisocial behaviors. In this context, increased understanding of the cognitive underpinnings of antisocial behavior, and how best to support sound cognitive development are therefore relevant to the furthering of rehabilitative practice. This thesis expands on existing knowledge by examining interned adolescents from an executive functions framework and also investigates how it relate to other constructs of clinical relevance.

    This is done in three empirical studies. The first two are cross-sectional and aimed at assessing a number of cognitive constructs and associated behaviors. The third study is aimed at examining the effects of a training intervention on said constructs. The studies indicated poorer pre-test performance by the interned adolescents as compared to their non-interned counterparts. However, no deficits specific to any one executive function was discernable. The results also showed that the internees self-reports expressed more perceived problems with inhibiting behaviors and managing unplanned prompts to shift from a planned activity. They also indicated it harder to resist impulsive behaviors related to negative affect, lower premeditative ability, and had more issues with persevering in prolonged tasks. In addition, there were a few connections between the performance-based and the self-reported accounts of executive functioning. Of particular interest was that the majority of group effects in self-reported constructs was related to the specific executive function updating, a finding not previously reported. This executive function has previously been suggested to be antecedent of antisocial behavior though. As for the training, the only substantial improvement was to perceptual speed, which occurred irrespective of training progression or experimental condition. This was mirrored by the posttest self-reports whose rather modest gains were also unrelated to both experimental conditions and training improvements.

    In conclusion, executive functioning and trait-based cognition are related to some degree, and both associate to antisocial behavior as operationalized by internment status. Process-based cognitive training can however not feasibly be determined to affect or alter these relations.

  • Public defence: 2018-03-16 10:00 KBC-huset, Lilla Hörsalen, KB.E3.01, Umeå
    Wang, Zhao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Recalcitrance of wood to biochemical conversion: feedstock properties, pretreatment, saccharification, and fermentability2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lignocellulose is an inexpensive and abundant renewable resource that can be used to produce advanced biofuels, green chemicals, and other bio-based products. Pretreatment and efficient enzymatic saccharification are essential features of bioconversion of lignocellulosic biomass. The aims of the research were to achieve a better understanding of the recalcitrance of woody biomass to bioconversion, to explore different pretreatment techniques that can be used to decrease the recalcitrance of the biomass and improve the digestibility of the cellulose, and to investigate by-products of acid pretreatment that cause enzymes and microorganisms to work less efficiently.

    The recalcitrance of wood from aspen, birch, and spruce was investigated before and after acid pretreatment. Before pretreatment, birch exhibited the highest recalcitrance, which was attributed to structural factors. After pretreatment, spruce showed the highest recalcitrance, which was attributed to chemical factors, such as high lignin content. Deacetylation of hybrid aspen in planta by a CE5 acetyl xylan esterase decreased the recalcitrance, and the glucose yield of enzymatic saccharification of non-pretreated wood increased with 27%.

    Pretreatment options based on ionic liquids and steam explosion were further explored. The effects of the anionic constituents of a series of imidazolium-based ionic liquids on pretreatment of aspen and spruce were investigated. [HSO4]− was efficient only for aspen, which was attributed to acid degradation of xylan. [MeCO2]− was efficient for both aspen and spruce, which was attributed to its capability to create a disordered cell wall structure rather than to removal of lignin and hemicellulose. A comparison was made between using sulfuric acid and sulfur dioxide for pretreatment of spruce. Although sulfur dioxide resulted in a pretreatment liquid that was more inhibitory to both enzymes and yeast, it was still superior to pretreatment with sulfuric acid, a phenomenon that was attributed to the particle size of the pretreated material.

    In a comparison of microbial inhibitors in pretreatment liquids from steam explosion of spruce, formaldehyde was found to be the most important inhibitor of yeast. Enzyme inhibition by catalytically non-productive adsorption to lignins and pseudo-lignin was investigated using quantitative proteomics. The results indicate that protein adsorption to pseudo-lignin can be as extensive as adsorption to real lignin. 

  • Public defence: 2018-03-16 13:00 N460, Naturvetarhuset, Umeå
    Hagman, Henrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Co-firing complex biomass in a CFB boiler: ash transformation, corrosion control and materials selection2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The effects of greenhouse gas net emissions on global warming, stricter legislation on waste handling, and the pursuit of ever cheaper heat- and power production are all important factors driving the introduction of complex fuels in incineration plants. However - without fundamental knowledge regarding ash transformation, corrosion control, and materials selection – this introduction of potentially economically and environmentally beneficial fuels, might instead cause economic loss and environmentally adverse effects.

    The present work is a contribution to the transition from today's CO2 net generating energy conversion system, to a more environmentally friendly and cost-efficient one. This is done using scientific methods to generate knowledge concerning mechanisms of ash transformation, corrosion control, and materials selection, in a co-fired industrial scale circulating fluidized bed (CFB) boiler, using a novel and biomass-based fuel mix, rich in Na, K, Cl, N, S, P, Ca and Si. Fuel fractions, ashes, flue gas, deposits, and construction material samples have been collected and analyzed using various techniques, including scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray Diffraction (XRD). The experimental results have been evaluated and interpreted using chemical equilibrium calculations.

    The results of this work include:

    1) An analysis of; the failure and preventive maintenance statistics of the industrial scale CFB boiler at hand; the elemental composition of boiler ashes and deposits, the flue gas composition and elemental composition of a multitude of fuel fractions; correlations between boiler design, operational parameters, elemental composition of deposits and boiler availability; a boiler elemental mass balance revealing details regarding deposit buildup mechanisms; properties of the fly ash relevant to flue gas filter design; and findings regarding the nitrogen chemistry of the novel and nitrogen-rich fuel mix.

    2) Speciation and description of the overall ash transformation and fireside alloy interaction, enabling the implementation of on-line corrosion control which significantly inhibits superheater and dew-point corrosion in the boiler; and, an equation describing the sulfation potential of the fuel mix, as a result of the direct and indirect interactions between all major ash-forming elements.

    3) A literature review relevant for the co-fired CFB cyclone vortex finder alloy selection and corrosion at 880 °C; An alloy selection study including long term exposures of several commercially available alloys identifying materials that are more than twice as cost-efficient as the often used alloy 253MA; a suggestion of novel methods for both systematic comparison of heavily degraded alloys, and for alloy service-life estimations; a detailed analysis of heavily degraded alloys 310S, 800H/HT and 600, identifying the driving corrosion mechanisms of the VF alloy degradation, including aspects of how the alloy internal mass transport and fireside surface interaction develops over time.

    The knowledge gained during this project has been used in the improvement work of the Perstorp 50 MWth CFB boiler, improving the boiler availability with 7 %, reducing the overall energy conversion costs with around 1.7 MEUR/year.