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  • Public defence: 2017-04-24 10:00 T2, Stockholm
    Zhu, Lin
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology.
    Structural studies of HDL and applications of EM on membrane proteins2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A large number of proteins interact with biological membranes, either integrated in the membrane (PepTSo2), embedded on a membrane surface (5-lipoxygenase) or encircling a cutout of lipid bilayer (apolipoprotein1 (apoA-I). They function as transporters, receptors or biocatalysts in cellular processes like inflammation or cholesterol transport which are touched upon here. Malfunction of specific membrane proteins are the cause for several diseases or disorders.

    Knowledge of protein structure supports understanding of its mechanism of function. Here, transmission electron microscopy (TEM) was used for structure determination. To obtain structure information to high resolution for membrane proteins, normally surrounded by lipids, demands specific methods and materials for stabilization. Stabilized in detergent the structure of the bacterial transporter PepTSo2 was shown to form a tetramer even bound to substrate. However, with a protein based stabilizer, Salipro, the structure of PepTSo2 could be determined to high resolution.

    High density lipoprotein (HDL) in blood plasma, involved in the removal of cholesterol from peripheral tissues, have a central role in cardiovascular function, metabolic syndrome and diabetes.

    The HDL-particle is composed of two copies of ApoA1 and around hundred lipid molecules. From TEM data, for the first time the clearly discoidal shape could be shown by 3-dimendional reconstructions. These were used for modelling the ApoA1 protein dimer by a "biased fitting" procedure. The results indicate how ApoA1 folds around a lipid bilayer in a disc-shaped structure.

    Modified HDL called nanodiscs were here used to show the Ca2+ dependent binding of 5-lipoxygenase on the nanodisc bilayer and thereby increased production of the inflammatory mediator leukotrieneA4. Dimerization of 5-lipoxygenase inactivates these functions.

  • Public defence: 2017-04-26 13:00 F3, Stockholm
    Moyo, Kerbina
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Real Estate Planning and Land Law.
    Women's Access to Land in Tanzania: The Case of the Makete District2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Access to land is crucial for combating discrimination. Women who are denied such access tend to be disadvantaged, a pattern that results in economic powerlessness. Tanzana is among the most undeveloped nations in the world, where gender inequalities with respect to accessing land are central problems. This study consequently aims at investigating women's access to land through customary land tenure in the Makete district in Tanzania. A case study strategy was adopted to address the research problem, whereby interviews, focus group discussions and documentary reviews were the main data collection methods.

    The findings indicate that the majority of women within villages are illiterate; unaware of any existing entitlements and lacking insufficient assets to fight for their rights, and that their involvement in land administration institutions is limited. At the familiy level, daughters and women are deprived of any right to possess land through inheritance because relatives believe they will be married to other families from which they will then gain access to land. This generally has been proven not to be the case. After marriage, women commonly are apportioned land strictly for crop cultivation (usufruct rights). Consequently, there are many challenges in realising women's property rights in Tanzania. These challenges include the dualisim of the property rights system: customary tenure operates alongside statutory tenure; inadequate knowledge about women's property rights by both women and men; negative attitudes towards women's influence, position, capability and reputation; outdated customs; archaic and conflicting interests in laws; and lack of legal capacity (empowerment) as to property rights.

    The most important tools for meeting these challenges include education and awareness campaigns that are designed to build the capacity of citizens as to the necessity of equity in access to property rights (land) using various legal tools at varying levels. Other measures include amending and repealing outdated laws, including provisons dicriminating against women's property rights and contradicting constitutional provisons and other international instruments. Other avenues are advocacy and working for behavioural chages can also be invoked by empowering individuals at all stages of life, supporting their involvement in productive activities and creating group networks, and facilitating the formation of community-based organisations as well as building capacity by mainstreaming land adminstration institutions.

  • Public defence: 2017-04-28 10:00 F3, Stockholm
    Österlind, Tomas
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Machine and Process Technology.
    Estimation of Machining System Dynamic Properties - Measurement and Modelling2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dynamic characteristics of machining systems are analysed for improved understanding of both structural and process properties. The thesis stresses the use of testing methods under operational like conditions as these are more representative of closed loop systems, such as machining systems, as compared to conventional testing methods.

    The test instrument proposed is a contactless excitation and response system, developed for testing of machine tool spindles under load and with rotating spindle. The instrument uses electromagnetic excitation and displacement sensors for analysis of rotating milling tools subject to load. A graphical tool for displaying and analysing rotor displacement was developed in conjunction with this.

    A modelling procedure for both off-line and on-line estimation of dynamic properties of mechanical structure and process information is presented. The proposed auto-regressive moving average models enable calculation of operational dynamic parameters and they can be estimated in a recursive manner, thus enabling real-time monitoring. The discrimination between stable and unstable processes, both in turning and milling, was performed by analysing the damping obtained from the operational dynamic parameters.

  • Public defence: 2017-04-28 10:00 Kollegiesalen, Stockholm
    Wåhlander, Martin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Controlled Polymer Grafting from Nanoparticles for the Design of Dielectric Nanocomposites2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The interest for polymeric nanocomposites has rapidly grown during the last decades, fuelled by the great potential and superior properties of nanoparticles (NPs). The production volumes of commercial NPs have increased exponentially during the last ten years, and the quality has been significantly improved. The aim of this study was to design polymer grafted commercially available metal-oxide NPs, and graphene oxide (GO), to develop isotropic (homogeneous) and anisotropic (heterogeneous) polymer nanocomposites for dielectric applications. The motivation was to formulate functional insulation materials for compact components in future power-grid systems using high-voltage direct-current (HVDC) or high-voltage alternating-current (HVAC), and to fabricate responsive sensor materials for monitoring e.g. temperature and voltage fluctuations in so called “Smart Grids”.

    Aluminium oxide (Al2O3), zinc oxide (ZnO) and reduced GO (rGO) NPs were modified with sparse polymer grafts via a controlled “covalent route” and were mixed with silicone (PDMS) or polyethylene matrices (EBA and LDPE) commonly used in HV-cable systems. The graft length and the graft-to-matrix compatibility were tailored to obtain nanocomposites with various self-assembled NP-morphologies, including well-dispersed, connected and phase-separated structures. The graft length was used to adjust the inter-particle distance of nanocomposites with continuous morphologies or connected (percolated) NPs. It was found that nanocomposites with percolated NPs and short inter-particle distances exhibited 10-100 times higher conductivity than the unfilled (neat) polymer, or displayed a rapid non-linear increase in conductivity (~1 million times) with increasingelectric field, while well-dispersed NPs with long inter-particle distances exhibited 10-100 times lower conductivity (i.e. higher resistivity) as an effect of their trapping of charge carriers. These tunable and functional properties are desirable for HV-insulation, field-grading applications, and flexible electronics.

    In addition it was shown that GO modified with dense polymer grafts via a “physisorption route” formed suspensions with liquid crystals, or matrix-free GO-composites with well-dispersed GO in isotropic or nematic states. These materials were reinforced by the GO, and exhibited elevated glass transition temperatures and a rapid thermo-responsive shape-memory effect, and are thus proposed to have a great potential as sensor materials and responsive separation membranes.

    The full text will be freely available from 2017-11-09 10:30
  • Public defence: 2017-04-28 14:00 Kollegiesalen, Stockholm
    Fu, Jiali
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Evaluating and Improving the Transport Efficiency of Logistics Operations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis focuses on evaluating and improving the transport efficiency of two types of logistics operations in the supply chain.

    One research area is the production of raw material in construction operations, specifically earthmoving operations. Methods and tools are developed to provide decision support in improving the transport efficiency of earthmoving at the vehicle and the systems levels. Using known road topography and a GPS unit, an optimal control problem is formulated and solved (Paper III) to determine the optimal gear shift sequence and timing in order to improve the transport efficiency at the vehicle level. For decision support at the systems level, a Fleet Performance Simulation (FPS) model is designed (Paper IV) to evaluate the transport efficiency for a given mix of construction vehicles in earthmoving. The FPS system is integrated with an optimization algorithm to solve the optimal fleet composition problem for earthmoving operations (Paper V & VI). Construction operations are dynamic and the environment is changing constantly, which bring difficulties in decision-making. Using GPS data from construction vehicles, a map inference framework (Papers I & II) is developed to automatically extract relevant input to decision support at the vehicle and the systems levels, which include the locations of various workstations, driving time distributions and road networks.

    The second research area is the transport efficiency of urban distribution system, which is in the final phase of the supply chain. An off-peak delivery pilot project in Stockholm is used as the background, designed to evaluate the potential for commercial vehicles to make use of off-peak hours for goods delivery. The thesis (Paper VII) evaluates the transport efficiency impacts of the off-peak pilot. An evaluation framework is defined where transport efficiency is studied in a number of dimensions. GPS data, fleet management data, and logistic information are used to assess the impacts.

  • Public defence: 2017-05-03 10:00 Kollegiesalen, Stockholm
    Yang, Guomin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Interfacial properties of calcium montmorillonite in aqueous solutions: Density functional theory and classical molecular dynamics studies on the electric double layer2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The swelling properties of Bentonite are highly affected by clay content and the clay-water interactions that arise from the ion distribution in the diffuse double layer formed near the charged montmorillonite (or smectite) surfaces. Existing continuum models describing the electric double layers, such as classical Poisson-Boltzmann and DLVO theory, ignore the ion-ion correlations, which are especially important for multivalent ions at high surface charge and ionic strength. To better understand the clay-water interactions, atomistic models were developed using both density functional theory of fluids (DFT) as well as classical molecular dynamics (MD) methods. In order to increase our understanding of water-saturated, swelling smectite clays, a DFT, technique was initially developed that allowed more accurate predictions of important thermodynamic properties of the diffuse double layers. This DFT approach was then extended to handle systems with mixtures of different sizes and charges. The extended DFT model was verified against experiments and Monte-Carlo simulations. One practical application was to predict the ion exchange equilibria in Bentonite clays, which have wide practical usage in different areas. Nevertheless, in the DFT work it was realized that DFT demands that the particles, ions in this case, which are described as hard spheres, realistically cannot be described as such at low water loadings, when ion specific hydration forces govern the electric double layer properties. To study how the deformation of the hydration shells of Ca2+ influences the properties of compacted smectite clays, MD simulations using the CLAYFF forcefield were employed in order to account for the deformation of the hydration shells. Comparisons of DFT and MD modeling then allowed to demonstrate under which conditions DFT modeling becomes increasingly inaccurate and when it still can give accurate results.

  • Public defence: 2017-05-04 10:00 F3, Stockholm
    Elwinger, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Characterizing Chromatography Media: NMR-based Approaches2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Liquid chromatography is an essential technique in manufacturing biopharmaceuticals where it is used on all scales from analytical applications in R&D to full-scale production. In chromatography the target molecule, typically a protein, is separated and purified from other components and contaminants. Separation is based on different affinities of different molecules for the chromatographic medium and the physical and chemical properties of the latter determine the outcome. Controlling and designing those properties demand efficient analytical techniques.

    In this thesis the approach was to develop characterization methods based on nuclear magnetic resonance (NMR) spectroscopy for the assessment of various important physico-chemical properties. The rationale behind this strategy was that the versatility of NMR – with its chemical and isotopic specificity, high dynamic range, and direct proportionality between the integral intensity of the NMR signal and the concentration of spin-bearing atomic nuclei (e.g., 1H, 13C, 31P and 15N) – often renders it a very good choice for both qualitative and quantitative evaluations.

    These characteristics of NMR enabled us to develop two quantification methods for chromatography-media ligands, the functional groups that provide the specific interactions for the molecules being separated. Furthermore, a new method for measuring the distribution of macromolecules between the porous chromatographic beads and the surrounding liquid was established. The method, which we have named size-exclusion quantification (SEQ) NMR, utilizes the fact that it is possible to assess molecular size distribution from corresponding distribution of the molecular self-diffusion coefficient where the latter is accessible by NMR. SEQ-NMR results can also be interpreted in terms of pore-size distribution within suitable models. Finally, we studied self-diffusion of small molecules inside the pores of chromatographic beads. The results provided new insights into what affects the mass transport in such systems.

    The methods presented in this thesis are accurate, precise, and in many aspects better than conventional ones in terms of speed, sample consumption, and potential for automation. They are thus important tools that can assist a better understanding of the structure and function of chromatography media. In the long run, the results in this project may lead, via better chromatographic products, to better drugs and improved health.

  • Public defence: 2017-05-05 13:00 Kollegiesalen, Stockholm
    Deckner, Fanny
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Vibration transfer process during vibratory sheet pile driving: from source to soil2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Vibratory driven sheet piles are a cost-effective retaining wall structure, and in coming decades the continued use of this method will be crucial for minimising costs within the construction sector. However, vibratory driven sheet piles are a source of ground vibrations, which may harm structures or induce disturbance. Most urban construction projects face strict limits on permissible vibration level. Being able to reliably predict the expected vibration level prior to construction is therefore highly important. Reliable prediction demands a profound knowledge of the vibration transfer process, from source to point of interest. This thesis focuses on clarifying the vibration transfer process and will serve as a platform for the future development of a reliable prediction model. The vibration transfer process is divided into two main parts: vibration source and vibrations in soil. The different parts in the vibration transfer process are studied and investigated with the help of a literature review, field tests and numerical modelling. Within the scope of this thesis, three field tests have been conducted and a new instrumentation system has been developed. The new instrumentation system enables recording of both sheet pile vibrations and ground vibrations at depth during the entire driving. The field tests aimed to study the vibration transfer from sheet pile to soil and the vibration transfer within a sheet pile wall, as well as the wave pattern in soil. To study sheet pile behaviour during driving a numerical model was developed, which is also meant to serve as a basis for further studies. The main scientific contribution of this thesis is the identification of the sheet pile behaviour during driving. For practical application, the main contribution is the development of an increased knowledge of the vibration transfer process from source to soil, together with the new instrumentation system and the development of the numerical model.

  • Public defence: 2017-05-09 13:00 F3, Stockholm
    Tully, Philip
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST). University of Edinburgh School of Informatics.
    Spike-Based Bayesian-Hebbian Learning in Cortical and Subcortical Microcircuits2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cortical and subcortical microcircuits are continuously modified throughout life. Despite ongoing changes these networks stubbornly maintain their functions, which persist although destabilizing synaptic and nonsynaptic mechanisms should ostensibly propel them towards runaway excitation or quiescence. What dynamical phenomena exist to act together to balance such learning with information processing? What types of activity patterns

    do they underpin, and how do these patterns relate to our perceptual experiences? What enables learning and memory operations to occur despite such massive and constant neural reorganization? Progress towards answering many of these questions can be pursued through large-scale neuronal simulations. 

     

    In this thesis, a Hebbian learning rule for spiking neurons inspired by statistical inference is introduced. The spike-based version of the Bayesian Confidence Propagation Neural Network (BCPNN) learning rule involves changes in both synaptic strengths and intrinsic neuronal currents. The model is motivated by molecular cascades whose functional outcomes are mapped onto biological mechanisms such as Hebbian and homeostatic plasticity, neuromodulation, and intrinsic excitability. Temporally interacting memory traces enable spike-timing dependence, a stable learning regime that remains competitive, postsynaptic activity regulation, spike-based reinforcement learning and intrinsic graded persistent firing levels. 

     

    The thesis seeks to demonstrate how multiple interacting plasticity mechanisms can coordinate reinforcement, auto- and hetero-associative learning within large-scale, spiking, plastic neuronal networks. Spiking neural networks can represent information in the form of probability distributions, and a biophysical realization of Bayesian computation can help reconcile disparate experimental observations.

  • Public defence: 2017-05-12 10:00 FR4, Stockholm
    Bass, Tarek
    KTH, School of Biotechnology (BIO), Protein Technology.
    Affibody molecules targeting HER3 for cancer therapy2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The development of targeted therapy has contributed tremendously to the treatment of patients with cancer. The use of highly specific affinity proteins to target cancer cells has become a standard in treatment strategies for several different cancers. In light of this, many cancer cell markers are investigated for their potential use in diagnostics and therapy. One such marker is the human epidermal growth factor receptor 3, HER3. It has been established as an important contributor to many cancer types. The function of HER3 is to relay cell growth signals from outside of the cell to the inside. Interfering with- and inhibit- ing the function of HER3 has emerged as an interesting strategy for cancer therapeutics. The studies presented in this thesis aim to target HER3 with small, engineered affinity domain proteins for therapeutic purposes. Monomeric affibody molecules have previously been engineered to bind and inhibit HER3 in vitro. Due to the relatively low expression of HER3, an increase in valency appears promising to strengthen the therapeutic potential. Affibody molecules targeting the receptor were thus linked to form bivalent and bispecific constructs and evaluated both in vitro and in vivo. In the first study of this thesis affibody molecules specific for HER3 and HER2 were fused to an albumin binding domain to form bivalent and bispecific construct. The constructs inhibited ligand-induced receptor phos- phorylation of both HER2 and HER3 more efficiently than monomeric affibody molecules. A second approach to enhance the potential of affibody molecules in tumor targeting is described in the second study, where monomeric HER3-binding affibody molecules were engineered to increase their affinity for HER3. The resulting variants showed a 20-fold in- creased affinity and higher capacity to inhibit cancer cell growth. Combining the findings of the first two studies, the third study describes the evaluation of a HER3-targeting bivalent affibody construct for potential application as a therapeutic. Here, the bivalent construct inhibited cancer cell growth in vitro and was found to slow down tumor growth in mice, while being well tolerated and showing no visible toxicity. The fourth study built upon these findings and compares a very similar bivalent construct to the clinically-investigated HER3-specific monoclonal antibody seribantumab. The affibody construct showed very comparable efficacy with the antibody in terms of decreasing tumor growth rate and ex- tending mouse survival. Collectively, these works describe for the first time the use of alternative affinity protein constructs with therapeutic potential targeting HER3.

  • Public defence: 2017-05-12 10:00 E3, Stockholm
    Kucheev, Yury
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Shooting Stars: The Value of Ranked Analysts' Recommendations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Financial analysts play a key role in collecting, processing and disseminating information for the stock market. Selecting the best analysts among thousands of analysts is an important task for investors that determines future investment profitability. Extensive research has been dedicated to finding the best analysts of the market based on various criteria for different clienteles. The state of the art approach in this process has developed into so-called Star Rankings with lists of top analysts who have previously outperformed their peers. How useful are such star rankings? Do the recommendations of stars have higher investment value than the recommendations of non-stars (i.e., recommendations of Stars “shoot” more precisely before and after selection)? Or do star rankings simply represent the past performance that will regress to the mean in the future (i.e., in reality, Shooting Stars are not stars and quickly disappear from the sky)?

    The aim of this Ph.D. thesis is to empirically investigate the performance of sell-side analysts’ recommendations by focusing on a group of star analysts. This thesis comprises four papers that address two overarching questions. (1) Do star rankings capture any true skill, and, thus, can investors rely on the rankings? (Papers I and II) (2) How do market conditions impact star analysts? (Papers III and IV)

    Paper I examines the profitability persistence of the investment recommendations from analysts who are listed in the four different star rankings of Institutional Investor magazine, StarMine’s “Top Earnings Estimators”, “Top Stock Pickers” and The Wall Street Journal and shows the predictive power of each evaluation methodology. By investigating the precision of the signals that the various methodologies use in determining who the stars are, the study distinguishes between the star-selection methodologies that capture short-term stock-picking profitability and the methodologies that emphasize the more persistent skills of star analysts. As a result, this study documents that there are star-selection methods that select analysts based on more enduring analyst skills, and, thus, the performance of these methods’ stars persists even after ranking announcements. The results indicate that the choice of analyst ranking is economically important in making investment decisions.

    Paper II investigates the structure of the portfolios that are built on the recommendations of sell-side analysts and confirms that the abnormal returns are explained primarily by analysts’ stock-picking ability and only partially by the effect of over-weight in small-cap stocks. The study examines the number of stocks in the portfolios and the weights that are assigned to market-cap size deciles and GICS sectors and performs an attribution analysis that identifies the sources of overall value-added performance.

    Paper III examines the differences in seasonal patterns in the expected returns on target prices between star and non-star analysts. Although the market returns in the sample period do not possess any of the investigated seasonal effects, the results show that both groups of analysts, stars and non-stars, exhibit seasonal patterns and issue more optimistic target prices during the summer, with non-stars being more optimistic than stars. Interestingly, the results show that analysts are highly optimistic in May, which contradicts the adage “Sell in May and go away” but is consistent with the notion of a trade-generating hypothesis: since analysts face a conflict of interests, they may issue biased recommendations and target prices to generate a trade. A detailed analysis reveals that the optimism cycle is related to the calendar of companies’ earnings announcements rather than the market-specific effects.

    Paper IV discusses how a shift in economic conditions affects the competitiveness of sell-side analysts. The focus is on the changes that were triggered by the financial crisis of 2007-2009 and a post-crisis “uncertainty” period from 2010-2013. The study follows Bagnoli et al. (2008) in using a change in the turnover of rankings as a measure of a transformation in analysts’ competitive advantages. Paper IV extends their research and documents how different ranking systems capture analysts’ ability to handle changes in the economic environment. The results show that market conditions impact analyst groups differently, depending on the group’s competitive advantages.

  • Public defence: 2017-05-12 10:00 F3, Stockholm
    Hollertz, Rebecca
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Cellulose-based electrical insulation materials: Dielectric and mechanical properties2017Doctoral thesis, comprehensive summary (Other academic)
  • Public defence: 2017-05-12 10:00 Kollegiesalen, Stockholm
    Barreiro Fidalgo, Alexandre
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Experimental studies of radiation-induced dissolution of UO2: The effect of intrinsic solid phase properties and external factors2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dissolution of the UO2 matrix is one of the potential routes for radionuclide release in a future deep geological repository for spent nuclear fuel. This doctoral thesis focuses on interfacial reactions of relevance in radiation-induced dissolution of UO2 and is divided in two parts:

    In the first part, we sought to explore the effects of solid phase composition:

    The impact of surface stoichiometry on the reactivity of UO2 towards aqueous radiolytic oxidants was studied. H2O2 reacts substantially faster with stoichiometric UO2 than with hyperstoichiometric UO2. In addition, the release of uranium from stoichiometric UO2 is lower than from hyperstoichiometric UO2. The behavior of stoichiometric powder changes with exposure to H2O2, approaching the behavior of hyperstoichiometric UO2 with the number of consecutive H2O2 additions.

    The impact of Gd-doping on the oxidative dissolution of UO2 in an aqueous system was investigated. A significant decrease in uranium dissolution and higher stability towards H2O2 for (U,Gd)O2 pellets compared to standard UO2 was found.

    In the second part, we sought to look at the effect of external factors:

    The surface reactivity of H2 and O2 was studied to understand the overall oxide surface reactivity of aqueous molecular radiolysis products. The results showed that hydrogen-abstracting radicals and H2O2 are formed in these systems. Identical experiments performed in aqueous systems containing UO2 powder showed that the simultaneous presence of H2 and O2 enhances the oxidative dissolution of UO2 compared to a system not containing H2.

    The effect of groundwater components such as bentonite and sulfide on the oxidative dissolution of UO2 was also explored. The presence of bentonite and sulfide in water could either delay or prevent in part the release of uranium to the environment. The Pd catalyzed H2 effect is more powerful than the sulfide effect. The poisoning of Pd catalyst is not observed under the conditions studied.

  • Public defence: 2017-05-19 10:00 b1, Stockholm
    liu, qingming
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Kungliga Tekniska Högskolan.
    Numerical study of flow boiling in micro/mini channels2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Boiling phenomena in micro scale has emerged as an interesting topic due to its complexity and increasing usage in micro electronic and mechanical systems (MEMS). Experimental visualization has discovered five main flow regimes: nucleate boiling, isolated bubbles, confine bubbly flow, elongated bubbly (or slug) flow, and annular flow. Two of these patterns (confine bubbles and slug flow) are rarely found in macro channels and are believed to have very different heat transfer mechanisms to that of nucleate boiling.

    The development of a phenomenological model demands a deep understanding of each flow regime as well as the transition process between them. While studies in every individual flow pattern are available in literature, the mechanisms of transition processes between them remain mysterious. More specifically, how the isolated bubbles evolve into a confined bubbly flow, and how this further evolves into elongated bubbles and finally an annular flow. The effects of boundary conditions such as wall heat flux, surface tension, and interfacial velocity are unclear, too.

    The aims of this thesis are to develop and validate a new numerical algorithm, perform a comprehensive numerical study on these transition processes, uncover the transition mechanisms and investigate effects of boundary and operating conditions.

    Firstly, a sophisticated and robust numerical model is developed by combining a coupled level set method (CLSVOF) and a non-equilibrium phase change model, which enables an accurate capture of the two-phase interface, as well as the interface temperature.

    Secondly, several flow regime transitions are studied in this thesis: nucleate bubbles to confined bubbly flow, multi confined bubbles moving consecutively in a micro channel, and slug to annular flow transition. Effects of surface tension, heat flux, mass flux, and fluid properties are examined. All these regimes are studied separately, which means an appropriate initial condition is needed for each regime. The author developed a simplified model based on energy balance to set the initial and boundary conditions.

  • Public defence: 2017-05-19 10:00 F3, Stockholm
    Hu, Francis Jingxin
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Utilizing Solid Phase Cloning, Surface Display And Epitope Information for Antibody Generation and Characterization2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Antibodies have become indispensable tools in diagnostics, research and as therapeutics. There are several strategies to generate monoclonal antibodies (mAbs) in order to avoid the drawbacks of polyclonal antibodies (pAbs) for therapeutic use. Moreover, the growing interest in precision medicine requires a well-characterized target and antibody to predict the responsiveness of a treatment. This thesis describes the use of epitope information and display technologies to generate and characterize antibodies. In Paper I, we evaluated if the epitope information of a well-characterized pAb could be used to generate mAbs with retained binding characteristics. In Paper II, the epitope on the complement protein C5 towards Eculizumab was mapped with surface display, the results of which explained the non-responsiveness of Eculizumab treatment among a patient group due to a mutated C5 gene. With this in mind, we showed efficacy in treatment of the mutated C5 variants using a drug binding to another site on C5, suggesting that our approach can be used to guide treatment in precision medicine. In Paper III, a Gram-positive bacterial display platform was evaluated to complement existing platforms for selection of human scFv libraries. When combined with phage display, a thorough library screening and isolation of nano-molar binders was possible. In Paper IV, a solid phase method for directed mutagenesis was developed to generate functional affinity maturation libraries by simultaneous targeting of all six CDRs. The method was also used to create numerous individual mutants to map the paratope of the parent scFv. The paratope information was used to create directed libraries and deep sequencing of the affinity maturation libraries confirmed the viability of the combination approach. Taken together, precise epitope/paratope information together with display technologies have the potential to generate attractive therapeutic antibodies and direct treatment in precision medicine.

    The full text will be freely available from 2017-05-26 08:00
  • Public defence: 2017-05-22 10:00 M3, Stockholm
    Khan, MD. Ershad Ullah
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Renewables Based Polygeneration for Rural Development in Bangladesh2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Despite the country's rural electrification programme, kerosene is the predominant source for lighting, and unsustainable and polluting woody biomass is virtually the only option available for cooking. The rural population also struggles with unsafe drinking water in terms of widespread arsenic contamination of well water. The present work has taken an integrated approach in an attempt to mitigate problems through small-scale polygeneration, a concept linking renewable energy sources to these energy needs via novel energy conversion systems.

    Anaerobic digesters (AD) for biogas production are promising in the rural setting, and field surveys have identified problems in the construction, maintenance and operation of existing AD, particularly in overall performance of household digesters. Based on these results, a number of operational and technological improvements are suggested for employing digesters in polygeneration units. This study also examines one approach for small-scale, low cost arsenic removal in groundwater through air gap membrane distillation, a thermally-driven water purification technology.

    Integration of biogas production with power generation and water purification is an innovative concept that lies at the core of feasibility analyses conducted in this work. One of the case studies presents a new concept for integrated biogas based polygeneration and analyzes the techno-economic performance of the scheme for meeting the demand of electricity, cooking energy and safe drinking water of 30 households in a rural village of Bangladesh. The specific technologies chosen for the key energy conversion steps are as follows: plug-flow digester; internal combustion engine; and membrane distillation. One major concern is local feedstock availability for the digester, since a single feedstock is impractical to serve both cooking, lighting and water purification systems. In this circumstance solar PV could be a potential option for integrated hybrid systems.

    The full text will be freely available from 2017-05-22 10:05
  • Public defence: 2017-05-22 10:00 F3, Stockholm
    Huiran, Lu
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Wood-based Materials for Lithium-ion Batteries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lithium-ion batteries (LIB) have become very important recently as power sources for portable electronics and electric vehicles. Today non-renewable petroleum-based polymers are used as binders in state-of-the-art LIB. Therefore, it is essential to investigate alternative binders, which are environmentally friendly and inexpensive. Using wood-based materials, such as cellulose and lignin, could make the batteries more environmentally benign, cheaper and easier to produce.

    Lignin, a byproduct from the pulping industry and the second most abundant bio-polymer in wood, has been investigated for the first time as binder material for eco-friendly LIB. Both LiFePO4 (LFP) positive and graphite negative electrodes using pretreated lignin as binder exhibited good electrochemical performance. The drawback of lignin as binder is that its poor mechanical properties limit the preparation of a thick electrode, constraining the energy density for LIB.

    In order to meet the demands of flexible and bendable electronic devices, cellulose nanofibrils (CNF) as binder materials have been successfully fabricated for flexible batteries by a water-based paper making process. It showed excellent binding properties for different kinds of electrode materials, which were homogenously dispersed in its visible network. The flexible electrodes obtained good mechanical and electrochemical properties. A study of different CNF shows that the manufacturing process affects the performance of the electrodes.

    Another innovative LIB concept in this thesis was to build both lightweight and bendable LIB. Chopped carbon fibers (CF), bound by CNF, were demonstrated as both current collector and as a current collector-free negative electrode, produced by an easy filtration process. The gravimetric energy density was increased compared to cells with metallic current collectors. The CF-based lightweight and flexible electrode achieved a good cycling stability, rate capability, even after 4000 times of bending.

    The full text will be freely available from 2017-11-22 00:00
  • Public defence: 2017-05-24 10:00 Kollegiesalen, Stockholm
    Liu, Lipeng
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Physics of Electrical Discharge Transitions in Air2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Electrical discharges with a variety of different forms (streamers, glow corona, leaders, etc.) broadly exist in nature and in industrial applications. Under certain conditions, one electrical discharge can be transformed into another form. This thesis is aimed to develop and use numerical simulation models in order to provide a better physical understanding of two of such transitions, namely the glow-to-streamer and the streamer-to-leader transitions in air.

    In the first part, the thesis includes the two-dimensional simulation of the glow-to-streamer transition under a fast changing background electric field. The simulation is performed with a fluid model taking into account electrons. An efficient semi-Lagrangian algorithm is proposed to solve the convection-dominated continuity equations present in the model. The condition required for the glow-to-streamer transition is evaluated and discussed. In order to enable such simulations for configurations with large interelectrode gaps and long simulation times, an efficient simplified model for glow corona discharges and their transition into streamers is also proposed.

    The second part of the thesis is dedicated to investigate the dynamics of the streamer-to-leader transition in long air gaps at atmospheric pressure. The transition is studied with a one-dimensional thermo-hydrodynamic model and a detailed kinetic scheme for N2/O2/H2O mixtures. In order to evaluate the effect of humidity, the kinetic scheme includes the most important reactions with the H2O molecule and its derivatives. The analysis includes the simulation of the corresponding streamer bursts, dark periods and aborted leaders that may occur prior to the inception of a stable leader. The comparison between the proposed model and the widely-used model of Gallimberti is also presented.

  • Public defence: 2017-06-12 09:00 F3, Stockholm
    Stiehler, Beate
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Identification and assessment of luxury brand segments in the emerging markets: Case of South Africa2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Africa has been identified as an upcoming market in which luxury brands should secure future growth opportunities. A review of related academic literature, however, reveals that limited research has been conducted which focuses specifically on the continent’s luxury consumers. This gap in the literature highlights the need to further the body of knowledge on luxury consumer behaviour in this context. However, as the continent comprises a vast number of countries with diverse consumer profiles, it was decided that this study would focus on the assessment of the behaviour of the members of luxury consumer segments in the South African market.

    The specific areas that require research in order to establish an understanding of luxury consumer segments’ behaviour commenced from a review of different trends and developments in the South African market. The core trends, along with calls for further research on luxury brands in the international academic literature were combined to identify numerous avenues for further research. This eclectic approach aimed to not only contribute to an enhanced understanding of the behaviour of luxury consumer segments in the South African market, but to develop and extend the existing body of academic knowledge and literature on luxury brands.

    Four research questions were developed from both the identified avenues from the review of the trends in the market, and the calls for further research in the academic literature. Each of these questions was then addressed by four individual papers.  This thesis makes a number of contributions to the related body of knowledge as it details the behaviour of different luxury brand consumer segments in the South African market, thereby serving as a step towards addressing the gap in the literature on luxury consumers on the African continent. 

  • Public defence: 2017-06-13 12:00 Aula Perez Pulgar, Madrid, Spain
    Izadkhast, Seyedmahdi
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Aggregation of Plug-in Electric Vehicles in Power Systems for Primary Frequency Control2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The number of plug-in electric vehicles (PEVs) is likely to increase in the near future and these vehicles will probably be connected to the electric grid most of the day time. PEVs are interesting options to provide a wide variety of services such as primary frequency control (PFC), because they are able to quickly control their active power using electronic power converters. However, to evaluate the impact of PEVs on PFC, one should either carry out complex and time consuming simulation involving a large number of PEVs or formulate and develop aggregate models which could efficiently reduce simulation complexity and time while maintaining accuracy.

    This thesis proposes aggregate models of PEVs for PFC. The final aggregate model has been developed gradually through the following steps. First of all, an aggregate model of PEVs for the PFC has been developed where various technical characteristics of PEVs such as operating modes (i.e., idle, disconnected, and charging) and PEV’s state of charge have been formulated and incorporated. Secondly, some technical characteristics of distribution networks have been added to the previous aggregate model of PEVs for the PFC. For this purpose, the power consumed in the network during PFC as well as the maximum allowed current of the lines and transformers have been taken into account. Thirdly, the frequency stability margins of power systems including PEVs have been evaluated and a strategy to design the frequency-droop controller of PEVs for PFC has been described. The controller designed guaranties similar stability margins, in the worst case scenario, to those of the system without PEVs. Finally, a method to evaluate the positive economic impact of PEVs participation in PFC has been proposed.