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High-Entropy Oxides for Thermoelectric Application
No full textHigh-entropy oxides (HEOs) are a new class of single-phase inorganic materials with a high specific capacity, high structural stability, and super-electronic conductivity and exhibit a wide range of useful properties. HEOs are better semiconductor materials compared to traditional ones due to their lattice distortion. Because parameters, such as crystal symmetry, different lattice parameters, etc., have a significant influence on the thermal conductivity of the material, lowering it via phonon-phonon or phonon-electron scattering. The entropy stabilization produces the high stability of the phase but also can result in interesting properties of the materials due to the contribution of different elements through four main effects: high-entropy effect, severe lattice distortion, sluggish diffusion effect, and cocktail effect. This thesis identified potential HEOs with the chemical composition Co-Cr-Fe-Mn-Ni-O by doing a thorough literature review. During the research, we have focused on the synthesis process and electrical properties of the HEOs (Co0.33Cr0.22Fe0.22Mn0.11Ni0.11)3O4, (Co0.33Cr0.22Fe0.22Mn0.11Cu0.11)3O4, and (Co0.2Cr0.2Fe0.2Mn0.2Cu0.2)3O4. Oxides were synthesized via Spark Plasma Sintering and Solid-State Reaction resulting in obtaining two or more phases with different crystal structures for the materials (Co0.33Cr0.22Fe0.22Mn0.11Ni0.11)3O4, and single-phased for the (Co0.33Cr0.22Fe0.22Mn0.11Cu0.11)3O4 and (Co0.2Cr0.2Fe0.2Mn0.2Cu0.2)3O4 at specific synthesis conditions. As expected, obtained single-phased materials exhibit higher values of electrical conductivity, which is probably due to the less electron-phonon scattering. Two types of semiconductors are needed for thermoelectric applications: p- and n-type. Due to the different synthesis temperatures, materials with Ni were obtained in both types. This can lead to the production of the Peltier module with the same chemical composition inside. With the Ni-Cu substitution, it became easier to produce single-phased materials, probably due to the melting point of the reagents. These materials also presented higher electrical properties, which the changes in carrier concentration can explain due to the differences in the electronic structures. All obtained samples exhibit low values of the electronic part of thermal conductivity, which can lead to low values of total thermal conductivity. It shows that the main contributor to the thermal conductivity will be from the phonons (lattice thermal conductivity). Overall, the expected thermal conductivity for these materials should be lower compared to the traditional semiconductor materials due to the crystal distortion, which can lead to higher phonon-phonon and phonon-electron scattering. Furthermore, this research shows that HEOs with unequal content of metals can be produced as single-phase materials and have even better or similar electrical properties compared to known compositions. Also, these oxides with impurities still exhibit promising electrical properties
Rebuilding of stationary shoulder friction stir welding MP 159 probes by laser metal deposition using stellite 6 powder
No full textLaser Metal Deposition with Powder (LMDp) is an established additive manufacturing (AM) technique with great potential for repairing and remanufacturing high-value tools. This study demonstrates, for the first time, the successful remanufacturing of worn MP159 stationary shoulder friction stir welding (SS-FSW) probes using LMDp and Stellite 6 alloy. Two deposition strategies were investigated: continuous deposition and deposition with a 10-second interlayer cooling interval. The effects on microstructural evolution, bonding integrity, and mechanical performance were evaluated. The cooling-assisted process enabled the deposition of six homogeneous and geometrically precise layers, compared to four in the continuous build, while significantly reducing thermal accumulation. Microstructural characterization revealed dense, crack-free deposits with strong metallurgical bonding between Stellite 6 and the MP159 substrate. The heat-affected zone (HAZ) exhibited recrystallization and grain coarsening accompanied by a BCC→FCC phase transformation in the substrate, forming a ductile buffer that enhances durability. Interlayer cooling refined the dendritic morphology, minimized remelting, and reduced HAZ thickness from 80 µm to 30 µm, indicating improved thermal control. Microhardness profiles showed consistent values (500–550 HV) across deposited layers, with localized softening (300 HV) in the HAZ due to tempering. These results confirm that LMDp with controlled cooling provides a sustainable, high-integrity, and cost-effective approach for restoring cobalt-based FSW tools.CC-BY 4.0</p
The relation between linguistic accuracy and scoring of Swedish EFL students’ writing during a high-stakes exam
No full textThis paper examines the effect of linguistic accuracy (e.g., the lack of form, grammatical, and lexical errors) on scoring during the high-stakes national test of English in Swedish upper secondary school. Teachers are expected to score their own students’ texts with the help of assessment instructions containing benchmark texts (i.e., texts representing different score bands). The assessment instructions and the score bands provided to guide scoring are not explicit about how accuracy should influence scores. Two research questions were answered: As measured by ordinal regression, to what extent does linguistic accuracy predict rater scores? Do the texts scored by teachers reflect the graded example texts in terms of how linguistic accuracy predicts scores? The results revealed, amongst other things, that overall frequency of errors in texts significantly predicted scores as the model explained approximately 58 % of the variance in the outcome variable according to Nagelkerke’s pseudo R-squared. Accuracy also had a similar effect on scores in texts rated by teachers as in the benchmark texts. In relation to the findings, it was concluded that accuracy may have more of an impact on scores than constructs that are more explicit components of the score bands such as lexical complexity.Full text license: CC BY 4.0;</p
Structure and morphology of vesicular dispersions based on novel glycophospholipids with various monosaccharide head groups
No full textGlycophospholipids combine the structural versatility of phospholipids and carbohydrates, but their potential as excipients and performance in other related applications remains largely unexplored due to their low natural abundance. We have synthesized four novel phosphatidyl saccharide conjugates with different carbohydrate head groups; glucose, galactose, fructose and xylose by using a Phospholipase D catalysed transphosphatidylation reaction. The combination of Small Angle X-ray Scattering (SAXS) and Cryogenic Transmission Electron Microscopy (cryo-TEM) data allowed us to characterize the dispersed glycophospholipid vesicles in excess water and under physiologically relevant solution conditions in terms of their morphology and structure. The different carbohydrate head group generated a large variability of the vesicle structures. Lipids conjugated with glucose and fructose self-assembled into unilamellar vesicles whereas galactose and xylose conjugated lipids formed multilamellar structures. Phosphatidylgalactose conjugated lipids formed a high number of stacked bilayers, while the phosphatidylxylose equivalent assembled into aggregates with only a few bilayers. These results highlight how carbohydrate hydroxyl spatial arrangements strongly influence lipid packing and self-assembly. The versatility of this glycophospholipid platform offers opportunities to generate biocompatible and biodegradable phospholipid excipients with properties that can be tailored for specific applications
Urban Climate InteracTable : towards an immersive contextual data analysis platform to visualize and explore urban heat
No full textExtreme weather events, such as heat waves, are occurring more frequently and intensively, imposing new climate-adaptation demands on municipal planning. We conducted a design study across the domains of urban planning and urban climate research, and identified challenges regarding a lack of heat-related information in current planning processes, and the high complexity of effective climate data representation. To address these challenges, and so enhance the information flow between these domains, we developed Urban Climate InteracTable, an immersive interface that supports exploratory analysis of spatio-temporal climate simulation data integrated with an urban environment representation. We describe several use cases in which this interface can be utilized to assist with planning-related decision processes and to communicate heat-related phenomena. We present the feedback obtained from our collaborating domain experts and relevant external experts, and reflect on our experiences throughout the design study. From this, we offer insights for future research.Additional funding: Norrköpings fond för forskning och utveckling (Norrköping’s Fund for Research and Development) [KS2022/0257]</p
Ordering labour : a shifting labour regime of a 'green investment'
No full textThis chapter examines the evolving labour regime associated with the establishment of Northvolt’s battery factory in Skellefteå, Sweden, with particular attention to its socioeconomic impacts on the local community and migrant workers. Drawing on ethnographic fieldwork, the authors explore the rapid development of temporary housing solutions, the differentiation and disciplining of labour, and the challenges migrant workers face in adapting to the local context. The study illustrates how global green investments are reshaping local labour markets and housing policies, resulting in precarious and tightly regulated living and working conditions for migrant workers. These findings provide critical insights into the wider implications of green investments for labour mobility and social reproduction in peripheral regions.Incorrect ISBN in publication.This is a draft chapter. The final version is available in Handbook of Labour Mobility edited by R.H. Eriksson & H.K. Hansen, published in 2026, Edward Elgar Publishing Ltd.</p
From precision to perception: Human-in-the-loop evaluation of keyword extraction for internet-scale contextual advertising
No full textKeyword extraction is a foundational task in natural language processing, underpinning countless real-world applications. One of these is contextual advertising, where keywords help predict the topical congruence between ads and their surrounding media contexts to enhance advertising effectiveness. Recent advances in artificial intelligence have improved keyword extraction capabilities but also introduced concerns about computational cost. Moreover, although the end-user experience is of vital importance, human evaluation of keyword extraction performances remains under-explored. This study provides a comparative evaluation of prevalent keyword extraction algorithms with different levels of complexity represented by TF-IDF, KeyBERT, and Llama 2. To evaluate their effectiveness, a mixed-methods approach is employed, combining quantitative benchmarking with qualitative assessments from 855 participants through four survey-based experiments. The findings demonstrate that KeyBERT achieves an effective balance between user preferences and computational efficiency, compared to the other algorithms. We observe a clear overall preference for gold-standard keywords, but there is a misalignment between algorithmic benchmark performance and user ratings. This reveals a long-overlooked gap between traditional precision-focused metrics and user-perceived algorithm efficiency. The study underscores the importance of human-in-the-loop evaluation methodologies and proposes analytical tools to facilitate their implementation
Monitoring long-term trends of spatial and temporal flexibility in electricity systems
No full textThe long history of evolving energy systems is also the history of adding new forms of flexibility, from run-of-the-river hydropower with limited spatial and temporal flexibility to contemporary fossil-fuel based electricity systems allowing more flexibility due to storable and transportable fuel and controllable generation. The increasing shares of solar and wind energy, which are available everywhere, but not all the time, calls for new types of flexibility strategies. Monitoring changing patterns of flexibility strategies add to our understanding of the status and direction of long run energy system transformation. To capture such broad trends and allow for comparison across regions, this study develops two indicators: Gross spatial flexibility (GSF) and Gross temporal flexibility (GTF). The indicators are tested on a sample of countries including Australia, Germany-Luxembourg-Austria (GLA region), Sweden and the USA. By normalising storage and transmission capacity to average power demand these indicators are shown to enable comparisons across time and across regions of different sizes. At present, publicly available data in most countries remain insufficient for simple indicator construction and continuous updating. The German MaStR platform is an exception and could serve as inspiration for database construction in other countries.Research funding also provided by the Swedish Electricity Storage and Balancing Centre (SESBC) and Chalmers Energy Area of Advance. SESBC is funded by the Swedish Energy Agency together with five academic and twenty-eight non-academic partners.</p
From Wood to Advanced Materials: Multifunctional TEMPO-Oxidized Wood Nanofibril Networks as Wound Dressings and Energy Storage Device Separators
No full textThe overall aim of this thesis is to study (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO) oxidation of wood particles from a structure-property relationship. Herein, the focus is on the characterization of materials after oxidation, fibrillation, and network formation from various wood species as raw materials, namely softwood- and hardwood particles. This thesis also compares the properties of corresponding nanofibrils, and networks produced through TEMPO-oxidation of raw wood and never dried softwood pulp (NDSP), as well as to commercial TEMPO-oxidized pulp, offering insights into the one-step delignification and oxidation process of wood. It further examines the applications of the nanofibril networks in liquid-absorbed state, in relation to their use as wound dressings and supercapacitor separators, while comparing their performance with commercial materials such as bacterial cellulose (BC) and polyolefin membranes. This thesis demonstrates that TEMPO-oxidation of wood provides a simplified and direct method to produce cellulose nanofibril (CNF) networks, eliminating separate pulping and bleaching processes prior to TEMPO-oxidation. The method streamlines the process by reducing the treatment and washing steps along with the time required, offering a straightforward route compared to traditional multi-step approaches, while utilizing cost-efficient by-products of wood processing as raw materials, such as sawdust. TEMPO-oxidized wood nanofibril networks are shown to be multifunctional materials with potential use for biomedical and electrochemical applications. They exhibit promising properties for use as advanced wound dressings, including high liquid absorption, wet mechanical integrity, thermal stability, transparency, and biocompatibility with skin cells, in relation to commercially available BC wound dressings. Furthermore, the thickness and fabrication methods, such as suspension casting and vacuum-assisted filtration, were found to significantly influence the interconnection of nanofibril layers and allow tunable design of network properties. The thesis also highlights the effect of wood specie on the chemical and mechanical properties of the TEMPO-oxidized wood nanofibril networks. Hardwood particles were found more prone to TEMPO-oxidation, and their nanofibrils exhibited higher carboxylate content than TEMPO-oxidized softwood nanofibrils (TO-SWNFs). However, TO-SWNFs displayed lower cytotoxicity with primary skin cells and their networks displayed better mechanical properties in wet state, making them a more suitable material for wound dressing applications. Furthermore, it has also been studied here that reducing the amount of TEMPO catalyst in the adapted method could be achieved without negative effects on the properties of the resulting hydrogel networks when advanced wound dressing applications are considered. Additionally, other application areas of TEMPO-oxidized wood nanofibril networks as supercapacitor separators were explored, with the addition of kraft lignin (KL) into developed networks, which improved the network uniformity while enhancing the electrochemical performance in coin-cell assemblies. An optimal KL content of 10 wt% provided the best balance of mechanical integrity and capacitance, with higher KL content leading to a decline in both material properties and electrochemical performance. In conclusion, this thesis establishes that TEMPO-oxidation of wood particles is a promising approach for production of CNFs that self-assembles to mechanically robust, transparent and cytocompatible hydrogel networks with tunable material properties for different potential applications, namely wound dressings and energy storage device separators as studied herein. Heali