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  • Public defence: 2018-02-23 09:00 KBE301 (Lilla hörsalen), Umeå
    Blum, Kristin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Targeted and untargeted analysis of organic contaminants from on-site sewage treatment facilities: Removal, fate and environmental impact2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    On-site sewage treatment facilities (OSSFs) are widely used all over the world to treat wastewater when large-scale sewage treatment plants (STPs) are not economically feasible. Although there is great awareness that the release of untreated wastewater into the environment can lead to water-related diseases and eutrophication, little is known about organic contaminants and their removal by OSSFs, environmental load and fate. Thus, this PhD thesis aims to improve the knowledge about treatment efficiencies in current OSSFs, the environmental impact and fate of contaminants released from OSSFs, as well as how biochar fortification in sand filter (soil beds) OSSFs might increase removal of these contaminants. State-of-the-art analytical techniques for untargeted and targeted analyses were used and the results evaluated with univariate and multivariate statistics.

    Environmentally-relevant contaminants discharged from OSSFs were identified using untargeted analysis with two-dimensional gas chromatography mass spectrometry (GC×GC-MS) and a MS (NIST) library search in combination with a prioritization strategy based on environmental relevance. A method was successfully developed for the prioritized contaminants using solid phase extraction and GC×GC-MS, and the method was also applicable to untargeted analysis. This method was applied to several studies. The first study compared treatment efficiencies between STP and soil beds and showed that treatment efficiencies are similar or better in soil beds, but the removal among the same type of treatment facilities and contaminants varied considerably. Hydrophilic contaminants were generally inadequately removed in both types of treatment facilities and resulted in effluent levels in the nanogram per liter range.

    Additionally, several prioritized and sometimes badly removed compounds were found to be persistent, mobile, and bioavailable and two additional, untargeted contaminants identified by the NIST library search were potentially mobile. These contaminants were also found far from the main source, a large-scale STP, at Lake Ekoln, which is part of the drinking water reservoir Lake Mälaren, Sweden. The study also showed that two persistent, mobile and bioavailable contaminants were additionally bioaccumulating in perch. Sampling for this study was carried out over several seasons in the catchment of the River Fyris. Parts of this catchment were affected by OSSFs, other parts by STPs. Potential ecotoxicological risks at these sites were similar or higher at those affected by STPs compared to those affected by OSSFs. Mass fluxes per capita were calculated from these levels, which were higher at STP-affected than at OSSF-affected sites in summer and autumn, but not in winter. Possibly, the diffuse OSSF emissions occur at greater average distances from the sampling sites than the STP point emissions, and OSSF-affected sites may consequently be more influenced by fate processes.

    The studies carried out suggested that there is a need to improve current treatment technologies for the removal of hydrophilic contaminants. Thus, the final study of this thesis investigated char-fortified sand filters (soil beds) as potential upgrades for OSSFs using a combination of advanced chemical analysis and quantitative structure-property relationship modeling. Removal efficiencies were calculated from a large variety of contaminants that were identified by untargeted analysis using GC×GC-MS and liquid chromatography ion mobility mass spectrometry as well as library searches (NIST and Agilent libraries). On average, char-fortified sand filters removed contaminants better than sand, partly due to an enhanced removal of several hydrophilic contaminants with heteroatoms. After a two-year runtime, sorption and particularly biodegradation must have contributed to the removal of these compounds.

    Generally, the combination of targeted and untargeted analysis has proven valuable in detecting a large variety of organic contaminants, as well as unexpected ones. The results imply that OSSFs have similar or better removal efficiencies, similar or lower environmental risks and similar or lower mass fluxes per capita, compared to STPs. Biochar fortification can improve the removal of organic contaminants in soil beds, but further research is needed to find technologies that reduce the discharge of all types of organic contaminants.

  • Public defence: 2018-02-23 09:00 Sal D, unodT9, by 1D, plan 9, NUS, Umeå
    Starnberg, Josefine
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
    Neurodevelopment and cardiovascular risk in 7-year old children born with marginally low birth weight2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Being born preterm (<37+0 gestational weeks) or with low birth weight (LBW, <2500 g) has been associated with a number of adverse health outcomes later in life. Most studied are cardiovascular and neurodevelopmental consequences in those born preterm and with very LBW (<1500 g). However, a majority of LBW children are born with a birth weight between 2000 and 2500 g, herein referred to as marginally LBW. The long-term risk profile for this substantially large group of children, is not known.

    Aim: The aim of this study was to explore cardiovascular risk and neurocognitive development in marginally LBW children born in Sweden.

    Method: This was originally a randomized controlled double-blinded trial aiming to explore the effects of iron supplementation in 285 children born with marginally LBW. The children were randomized to receive 0 mg/kg/day (placebo), 1 mg/kg/day or 2 mg/kg/day of iron supplements between 6 weeks and 6 months of age. As part of this observational follow-up study, 95 matched control children born with normal birth weight (NBW, 2501-4500 g) were recruited former to the first follow-up at 3.5-years. This thesis presents data from a follow-up at 7 years, including anthropometric data, blood pressure (BP), body composition (from a dual-energy X-ray absorptiometry) and laboratory markers of cardiovascular risk such as fasting glucose, insulin and lipid profile. Also, the children were tested using the validated neurocognitive tests WISC-IV (Wechsler Intelligence Scale for Children), Beery VMI (Beery-Buktenica developmental test of visual-motor integration) and TEA-Ch (Test of Everyday Attention for Children).

    Results: The marginally LBW children were thinner (15.1 vs 15.5 kg/m2, p=0.046), shorter (122.4 vs 124.9 cm, p=0.001) and had a higher prevalence of underweight (10.7 % vs 2.9 %, p=0.050) compared to their NBW peers. In addition, the LBW children had a significantly larger prevalence of high fasting insulin levels (>90th percentile of the control group). The subgroup of children born small for gestational age (SGA) also had a higher mean fasting glucose level, compared to NBW controls. There were no differences in prevalence of overweight or having an adverse lipid profile between the groups. The marginally LBW children who had received iron supplements, as part of the original intervention trial, had approximately 2 mmHg lower systolic BP, compared to the placebo group (p=0.026). The odds of having a high BP was lowered by 68 % (OR 0.32; CI 0.11-0.96) in the supplemented groups.

    The marginally LBW children had 3.1 points lower verbal comprehension IQ (p=0.004), 3.5 points lower Beery VMI (p=0.028) and poorer selective attention compared to those born with NBW.

    Conclusions: The marginally LBW children were thinner and shorter and they had an imbalanced glucose and insulin homeostasis, particularly those born SGA. Early iron supplements lowered systolic BP to a level similar to controls, suggesting a novel hypothesis regarding a long term protective effect against adverse programming. Finally, the children born with marginally LBW had poorer neurocognitive outcomes, prompting particular attention at school age.

  • Public defence: 2018-02-23 10:00 Hörsal E, Humanisthuset, Umeå
    Fredriksson, Daniel
    Umeå University, Faculty of Arts, Department of culture and media studies.
    Musiklandskap: musik och kulturpolitik i Dalarna2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this thesis, I study how conditions for music-making can be developed, maintained and challenged through government support processes in the Swedish region Dalarna. The research questions focus on the ways music, policy and governance relate to each other, what kinds of musicians and ways of making music are favored in these relations, and the agency and meaning of place. The study is made through participant observation of musical events, cultural policy meetings, and the everyday practice of cultural policy officials; interviews with musicians, organizers and cultural policy officials; cultural policy documents as well as musicians’ and organizers’ public documents such as concert posters and websites.

    The musical landscape of Dalarna is summarized as a complex web with pathways that reach far beyond the geographical borders of the region. The cultural cooperation model works as a hierarchy from center to periphery, from the national government, through agencies, regional government, musical institutions and organizers, musicians and audiences. We can analyze all these practices as being part of music, as musicking. But we could also describe them another way, where the practice of cultural policy is dependent on and conditioned by the musical practices it is set to govern. In this way, musicians are always in some way also creating policy.

    I discuss genre hierarchies and further argue that music can, or should, not always be motivated by its effects on regional development or its social impact, it also needs to be allowed to be unhealthy and unprofitable. When we support music, we should be aware that it can be a hobby as well as a business, a serious artistic endeavor as well as play. And more often than not, music is all of these things at the same time.

  • Public defence: 2018-02-23 13:00 Sal B, NUS 1D-Tandläkarhögskolan, Umeå
    Ljungberg, Johan
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Cardiovascular risk factors in aortic stenosis2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Introduction: Aortic stenosis (AS) is the most common hemodynamic significant valvular heart disease and affects about 2% of the population. The incidence increases with age. When symptoms of the stenotic aortic valve disease eventually occur the 2-year mortality exceeds 50%. Aortic valve replacement (AVR) by surgery or by catheter intervention is the only known treatment. The causes of AS are only partly known, despite that the disease has been known since the beginning of 17th century. In younger individuals, a bicuspid valve is present in about 80% of the cases. The traditional cardiovascular risk-factors for ischemic heart disease have been linked to AS, and the histology of the stenotic aortic valve and the atherosclerotic plaques shares several features such as inflammation, lipid deposition and calcification. High levels of the lipoprotein Lp(a) has been linked to both atherosclerosis and AS, and a causal relation with AS is supported by Mandelian randomisation. End-stage renal disease is associated with increased risk of AS but if early impairment increases the risk is not known.

    Material and methods: We identified 799 patients with surgery for valvular heart disease and/or disease of the ascending aorta with a prior participation in one of three large population based health surveys in northern Sweden (Västerbotten Intervention Program [VIP], MONItoring Of trends and Determinants in CArdivascular Disease survey [MONICA], and the Mammary Screening Project [MSP]). For each case, four referents matched by age, gender, type and date of survey, and geographical area were randomly selected. From the health surveys, data on cardiovascular risk-factors and health history as well as measurements of anthropometry, blood pressure, glucose and cholesterol levels were retrieved. Each case was carefully validated and data from pre- and perioperative assessments were collected. The presence of coronary artery disease (CAD) was determined from the preoperative coronary angiogram. Apolipoproteins B and A1, Lp(a), creatinine and cystatin C were analysed in samples obtained at the initial survey. As this is a matched case-referent study where cases and referents had the same follow-up duration within strata, logistic regression using the conditional maximum likelihood routine designed for matched analysis was used to estimate odds ratios (ORs) with 95% confidence intervals. Studied variables were tested in uni- and multivariable models.

    Results: Paper 1: Of the identified 799 cases with questionnaires, 322 were primarily operated for AS, 91 for aortic regurgitation, 181 for mitral regurgitation, 131 for disease of ascending aorta, 52 for CAD (and for concomitant valvular or aortic disease). The remaining 22 had various indications for valvular heart surgery and were excluded. Altogether 38% of patients were women. Aortic stenosis: Hypertension (OR 1.87 [1.37–2.54]), diabetes (OR 1.78 [1.01–3.11]) and total cholesterol (OR 1.64 [1.07–2.49]) were associated with future AVR. After exclusion of concomitant CAD, none of the these risk-factors remained significant. Aortic regurgitation: None of the cardiovascular risk-factors was associated with increased risk for aortic regurgitation demanding surgery, whereas high levels of cholesterol were associated with reduced risk for surgery (OR 0.29 [0.12–0.71]). Mitral regurgitation: High levels of cholesterol associated with surgery for mitral regurgitation (OR 1.74 [1.01–3.00]), but not in those without CAD. Disease of the ascending aorta: Hypertension (OR 2.42 [1.44–4.06]) and previous smoking (OR 1.97 (1.12–3.49]) related to increased risk for surgery of the ascending aorta, whereas diabetes was inversely associated with surgery (OR 0.09 [0.01–0.73]). Excluding CAD, only diabetes remained protective (OR 0.24 [0.07–0.81]). Paper 2: 322 patients underwent AVR, and 70 had surgery before the age of 60 years and 252 had surgery after 60 years of age. After exclusion of patients with CAD, 49 and 82 patients remained in these age groups. Arterial hypertension associated with future AVR in those operated before the age of 60 years regardless of concomitant CAD or not (OR 3.40 [1.45–7.93] and OR 5.88 [1.46–23.72]). In those older than 60 years at surgery and with concomitant CAD, all traditional cardiovascular risk factors associated with surgery, but in those without concomitant CAD, only impaired fasting glucose (IFG) was associated with surgery (OR 3.22 [1.19–8.76]). Paper 3: 336 patients having surgery for AS. Lipoprotein(a) [Lp(a)] was independently associated with surgery in those with concomitant CAD (OR 1.29 [1.07–1.55]), but not in those without CAD. A high Apo B/A1 ratio was associated with surgery in patients with CAD (OR 1.43 [1.16–1.76]), but not in those without. Paper 4: The same cohort as in paper 3 was examined. Renal function was estimated by the ratio between glomerular filtration rates (eGFR) obtained from cystatin C and creatinine, and a low ratio indicates early impairment of renal function (“shrunken pore syndrome”). A high ratio independently associated with lower risk for future AVR (OR 0.84 [0.73–0.97]). Protective effect was seen in women but not in men (0.74 [0.60–0.92] and 0.93 [0.76 [0.76–1.13], respectively). After stratification for CAD, the association remained significant in women with CAD but not in men with CAD (0.60 [0.44–0.83] and 0.96 [0.76 [0.75–1.23], respectively).

    Conclusion: The traditional cardiovascular risk-factors associated with future surgery for valvular heart disease and for surgery of the ascending aorta, however with a clear difference if there was concomitant CAD or not. Arterial hypertension was a major risk factor for surgery for AS in younger patients without CAD, whereas impaired fasting glucose (IFG) associated with surgery in elderly patients without CAD. High levels of Lp(a) and a high Apo B/A1 ratio were associated with future AVR only in patients with concomitant CAD. Similarly, early renal impairment expressed as low ratio of eGFR by cystatin C and by creatinine (“shrunken pore”) associated with future AVR.

  • 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 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 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 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.