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Eldriven in situ-sanering av jord förorenad med arsenik och PAH
No full textContaminated soil is a global problem due to its association with environmental and health risks. The wood impregnation industry is one example that has left many sites co-contaminated with polycyclic aromatic hydrocarbons (PAH) and metal(loid)s, such as arsenic. Despite the negative environmental and economic aspects of landfilling, this is the most common soil remediation technology in Sweden and Europe. This study sought to investigate the effects of an electricity driven remediation on soil contaminated with arsenic and PAH, to contribute to the knowledge about using it as an alternative to landfilling. The technology can be practiced in situ, since it uses electricity applied over electrodes inserted into the soil. Novel for this study was the intentionally corroding iron rod electrodes, which sought to amend the soil with iron. This was done to allow for formation of iron oxides in the soil, which could immobilise arsenic by chemical adsorption, thereby reducing the risk of spreading of arsenic and lowering of its toxicity. Simultaneously, the intention was to degrade PAH with hydroxyl radicals, forming from hydrolysis of water molecules in the soil. What also stood out in this study is that a pulsating current was used instead of chemical additives for PAH desorption, prior degradation. To test the effects of the technology on arsenic immobilisation and PAH degradation in sand and peat, experiments were set up on laboratory and intermediate scales. An additional experiment was performed in microcosms to test how varying redox conditions affect arsenic immobilisation in treated soil. Results showed that the concentrations of arsenic and PAH decreased in both soil and soil solution. However, low redox conditions and high organic matter content were two factors reducing the remediation effect. During anoxic conditions, an increase was shown in the exchangeable arsenic fraction. Moreover, the treatment was more effective in sand than in peat, most likely due to its lower organic matter content. However, the treated soil performed better under oxidizing conditions in terms of promoting arsenic immobilisation, and under reducing conditions in terms of preventing arsenic remobilisation, compared to untreated soil. This study showed that electricity driven remediation can be suitable for arsenic immobilisation and simultaneous PAH degradation. It could be a potential alternative to landfilling, especially when taking site-specific conditions into account, and when combining it with other remediation techniques. However, more studies are needed to confirm that, and the exchangeable arsenic fraction needs to be reduced prior industrial implementation.Förorenad mark är ett globalt problem på grund av dess påverkan på hälsa och miljö. Träimpregneringsindustrin är ett exempel som har lämnat många platser samförorenade med polycykliska aromatiska kolväten (PAH) och metall(oid)er, såsom arsenik. Trots de negativa miljömässiga och ekonomiska aspekterna av deponering är detta den vanligaste marksaneringstekniken i Sverige och Europa. Denna studie syftade till att undersöka effekterna av en eldriven saneringsteknik på mark förorenad med arsenik och PAH, för att bidra till kunskapen om att använda den som ett alternativ till deponering. Tekniken kan användas in situ, eftersom den är eldriven och elektricitet appliceras över elektroder som förs ner i jorden. Innovativt för denna studie är de avsiktligt korroderande järnelektroderna, som syftade till att tillsätta järn till jorden, för att möjliggöra bildandet av järnoxider. Dessa järnoxider skulle kunna immobilisera arsenik genom kemisk adsorption och därigenom minska arsenikföroreningens toxicitet samt minska risken för dess spridning. Avsikten var att samtidigt bryta ner PAH med hydroxylradikaler, bildade genom hydrolys av vattenmolekyler i jorden. Originellt för denna studie är också användningen av en pulserande ström för den PAH-desorption som föregick nedbrytningen, istället för kemiska lösningsmedel. För att testa teknikens påverkan på immobilisering av arsenik och nedbrytning av PAH i sand och torv, genomfördes experiment på laboratorie- och mellanstor skala. Ytterligare ett experiment utfördes i mikrokosmer för att testa hur varierande redoxförhållanden påverkar immobilisering av arsenik i behandlad jord. Resultaten visade att koncentrationerna av arsenik och PAH minskade i både jord och grundvatten. Låga redoxförhållanden och hög halt organiskt material var dock två faktorer som minskade saneringseffekten. Under anoxiska förhållanden ökade den utbytbara arsenikfraktionen. Dessutom var behandlingen mer effektiv i sand än i torv, mest troligen på grund av sandens lägre innehåll av organiskt material. Den behandlade jorden uppvisade dock en större motståndskraft mot remobilisering under reducerande förhållanden och främjade immobilisering under oxiska förhållanden, jämfört med obehandlad jord. Studien visade att eldriven sanering kan vara lämplig för immobilisering av arsenik och samtidig nedbrytning av PAH. Den skulle kunna vara ett potentiellt alternativ till deponering, särskilt när man tar hänsyn till platsspecifika förhållanden och när man kombinerar den med andra saneringstekniker. Fler studier behövs dock för att bekräfta detta och den utbytbara arsenikfraktionen behöver reduceras före industriell implementering
Water-lubricated high-performance polymers
No full textPolymer-composites are indispensable tribo-materials in a wide range of engineering applications, including gears, bearings, joint implants, and automotive components. In many of these applications the presence of liquid lubricant is unavoidable, requiring a thorough understanding of composite behaviour under lubricated conditions. However, with growing emphasis on environmental safety, the use of petroleum oil-based lubricants, especially near aqueous environments, such as ships, pumps and turbines, has become increasingly dubious. Estimates suggest that of the 30–40 million tonnes of lubricant used annually, around 55% may eventually re-enter the environment, with approximately 95% of these being petroleum-based. These systems contribute to emissions and resource depletion, driving interest in the development of lubricant technologies free from petroleum-derived products. Some potential replacements to them are acceptable alternate lubricants like esters and glycerol, or mere water, which is abundantly available and emission free. The tribological performance of polymer composites often differs between dry and lubricated conditions, as contribution from polymer and fillers are observed to vary across environments. While numerous studies have explored the role of various fillers in water lubricated conditions, limited knowledge is available on other alternate lubricants. More recently, the focus on polymer-composite side has shifted towards multi-filler systems, which, when working synergistically, can provide superior performance compared to having a single filler. However, the existing literature lacks clarity on several key aspects: including the individual roles of filler material and scale; the nature and effect of filler–filler and filler–lubricant interactions to overall performance. This thesis investigates these gaps and provides deeper insights into the mechanisms governing the lubricated tribological behaviour of multi-filler polymer composites
Determination of the thermo-electronic and structural properties of polycrystalline metals and single-crystal semiconductors
No full textThis study explores the correlation between thermal, electrical, and structural properties of metals, alloys, and single-crystal semiconductors using photothermal techniques, electrical methods, and X-ray diffraction. Polycrystalline metals (Al, Pt, Ti, Cu, AISI 1030 steel, α-brass) and semiconductors (Si, GaSb-Te) were systematically analyzed. Thermal diffusivity was measured using Frequency Domain Photoacoustic (FDPA), and thermal conductivity and volumetric heat capacity using the Thermal Relaxation Method (TRM). A thermal diffusivity image for a Si sample was taken to show the influence of mechanical damage on the thermal transport properties. The structural properties were determined using X-ray diffraction, while the electrical properties were evaluated using the Van der Pauw method. The results show a strong correlation between the thermal, electrical, and structural properties of the materials, specifically with respect to crystallite size and space group. The thermal conductivity is influenced by the crystallite size, while electrical conductivity varies due to extrinsic factors, especially for polycrystalline metals. These results suggest that the Wiedemann-Franz theory needs to be re-evaluated by considering both intrinsic and extrinsic influences on material behavior
The effects of extramural English reading on phraseology in L2 writing: A key phrase frames approach
No full textForeign/second language (L2) learners worldwide are increasingly exposed to English outside the classroom through self-initiated, extramural English (EE) activities. Among the diverse types of EE activities, reading stands out as a particularly important activity for students. In particular, it has been shown to foster L2 learner's phraseological knowledge (e.g., phrasal verbs and collocations). This study explores whether the effects of EE reading extend to longer multi-word units by examining discontinuous four-word sequences with a variable slot occupied by fillers (e.g., the most ∗ aspect), known as phrase frames (p-frames). The present study used the Swedish Learner English Corpus (SLEC), which comprises L2 English texts written by junior and senior high school students, to extract texts from learners who read in English every week vs. those who do not. Subsequently, we used a novel method for identifying p-frames that are key to the reading and non-reading groups, respectively, and examined the variability of fillers and structural characteristics of the identified key p-frames. The results show that key p-frames of the reading group are characterized by higher variability than those in the non-reading group. There were very limited differences between the groups at the level of the structural categories, but specifically for the function word frames, the reading group are characterized by p-frames that involved a noun phrase with a post-nominal modifier (e.g., the ∗ of a). In contrast, the non-reading group included more embedded clauses in their texts. Pedagogical implications for the role of language exposure through self-initiated reading are discussed
Smart cities : the future with Artificial Intelligence
No full textArtificial Intelligence (AI) has become the latest technology disrupter that has the potential to dramatically change the nature of economy and sustainability in the decades to come. It is still in the nascent stage where wide spread adoption of AI methods including Machine Learning (ML), federated learning, unsupervised automation is still under the scrutiny for public sector adoption. As a foresight exercise, this chapter discusses the role of AI in cities. It provides an outlook on the use of AI in cities for city intelligence and their impact on Sustainable Development Goals (SDGs) as determined by the United Nations (UN). Use-cases, frameworks, and best practices for AI use in cities proposed by nations and international bodies are presented along with technical components that can enable AI adoption. Additionally, a detailed description of AI based techniques is provided to give a technical understanding of AI algorithms from academic and industry perspectives. The focus on data and federated components for discovery and interoperability enabling AI is presented to enable readers to build a vision for future connected urban AI ecosystems. Finally, concerns with the adoption of AI in the public sector are presented along with the conclusions of the chapter.
Charge-regulated reversal of acetate/chloride selectivity on functionalized graphene via dehydration-driven diffusion
No full textSeparating monovalent anions of similar size and charge, such as acetate (Ac−) and chloride (Cl−), remains highly challenging in membrane processes. Using molecular dynamics simulations, we explored functionalized graphene surfaces with tunable fractions of protonated amine (-NH3+) and deprotonated carboxyl (-COO−) groups (ratios 0:10 to 10:0) in a NaAc/NaCl mixed solution. We identified a charge-regulated selectivity reversal process: -COO−-rich, negatively charged surfaces showed only a weak Cl− preference (αCl−/Ac− = 1.06–2.71), whereas -NH3+-dominated, positively charged surfaces achieved strong Ac− selectivity, up to 14.86, for an 8:2 -NH3+:-COO− ratio. Decomposing permeability into solubility and diffusivity showed that the Ac− advantage on -NH3+-rich surfaces was more than 80 % diffusion-dominated, whereas the small Cl− preference on -COO− surfaces reflected slight, counterbalancing changes in solubility and diffusivity. Interfacial hydration analysis linked the selectivity to the dehydration difference between Ac− and Cl−. The maximum Ac−/Cl− selectivity coincided with the largest ΔNAc−-Cl− between the bulk and the interface. Together, our work reveals interfacial dehydration-controlled diffusion as the main mechanism for separating Ac− from Cl− on charge-regulated graphene surfaces and offers a quantitative design rule recommending setting the -NH3+:-COO− ratio near 8:2 to optimize membrane functionalization for challenging monovalent anion separations.Validerad;2025;Nivå 2;2025-11-21 (u4);Funder: National Natural Science Foundation of China (22378182, 22494713); the Jiangsu Provincial Department of Science and Technology (BK20232010); the State Key Laboratory of Materials-Oriented Chemical Engineering (SKL-MCE-22A02);This article is part of a Special issue entitled: ‘Desalination technology’ published in Separation and Purification Technology.</p
Pea protein isolates adsorption on phospholipid bilayer interfaces : a quartz crystal microbalance and neutron reflectometry study
No full textLegumin and vicilin, the main storage proteins from peas, are increasingly employed as functional ingredients for food. The purpose of this work was to better understand the interactions between these proteins and selected lipids, due to their potential consequences on interfacial functionality of protein preparations. Legumin and vicilin isolates were obtained after isoelectric precipitation followed by further purification using size exclusion chromatography. The interactions were studied using DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine): DOPE (1,2-dioleoyl-sn-glycero-3 phosphoethanolamine) as mixed supported lipid bilayers, using quartz crystal microbalance with dissipation monitoring (QCM-D) and complementary neutron reflectometry (NR) experiments. This approach, fundamental in nature, allowed to observe interactions at the molecular level in the presence of phospholipids interfaces. QCM-D data suggested that legumin did not show any significant affinity for the investigated lipid interface. On the contrary there were changes in the bilayer with vicilin injection. NR experiments also supported these observations, and modeling of the experimental data also suggested a structural reorganization of the bilayer after vicilin injection and rinsing. This unique fundamental study of legumin and vicilin leads to the hypothesis that vicilin forms complexes with phospholipids bilayers which can be dispersed and removed by rinsing. All together, this study adds to the current debate on the importance of endogenous and non-endogenous phospholipids presence in affecting surface functionality of pea protein isolates
On Cone Penetration Tests in Tailings : The need for a calibration chamber
No full textTailings is a fine-grained granular mine waste, typically with particle sizes in the range of sands to silts. Conventionally, tailings are hydraulically deposited into impoundments surrounded by tailings dams. The safety against dam failure must be ensured, as a failure can result in catastrophic consequences. In recent times, catastrophic tailings dam failures of upstream constructed dams have reported static (or flow) liquefaction in tailings as a failure mechanism. Static liquefaction can betriggered in saturated and loose silty sandy soils, generating a nearly complete strength loss in the soil. Undoubtedly, static liquefaction is a critical failure mode to investigate in the design of tailings dams, especially for cases where the dam stability relies on strength of the deposited tailings. In engineering practice, the primary focus for failure modes involving static liquefaction is to identify if the tailings are saturated and loose. If so, the tailings are considered to have liquefaction potential and it is common to assume that static liquefaction will occur independently of any triggering event. Thus, low strength values corresponding to a case of “liquefied” soil strength is used in the stability assessments and such scenarios typically governs the tailings dam design. The most challenging part of the liquefaction potential assessment is to investigate if the tailings are loose, which in this context refers to “looser” than its critical state at the current stress level indicated by contractive behaviour during shearing. Assessment of tailings state (i.e. loose or dense) is thereby crucial and engineering practice relies on in-situ testing, since undisturbed sampling in sandy soils is challenging. The Cone Penetration Test (CPT) is today the most used in-situ test for liquefaction assessments in sandy soils, including tailings deposits. However, existing CPT related interpretation methods were mainly developed based on natural clean sands and CPT conducted in calibration chambers. Using these interpretation methods on the CPT response in a loose silty-sandy tailings is thereby outside the original context in which the methods were derived. Concludingly, there are uncertainties in CPT interpretation of tailings state which become uncertainties inherent in the tailings dam design. In this thesis the usage of CPT for assessing the tailings state is further discussed, from physical measured CPT data, like cone tip resistance or pore pressure development during penetration, to interpreted parameters used in static liquefaction assessments. CPT as well as static liquefaction is highlighted from a perspective in close connection to the framework of Critical State Soil Mechanics. Uncertainties in the CPT interpretations in tailings are highlighted, with focus on deviating characteristics between tailings and natural sands that motivates the need for CPT calibration chamber testing on tailings. As part of the ongoing research a new calibration chamber has been designed and developed at LTU. The chamber is in detail presented in this thesis. In the chamber a sample with 0,6 m diameter and 1 m height can be prepared. Sample saturation and consolidation to desired conditions are conducted in the chamber prior to pushing a CPT. Details on how the CPT calibration chamber testing will be utilized in forthcoming research are presented in the thesis. Loose (contractive) silty sandy tailings will initially be tested to investigate the relation between tailings state and CPT data. In addition, other possibly relations between conditions for static liquefaction potential in tailings and CPT data are also of interest in the upcoming research
Promoting a Sustainable Digital Work Life for People with Cognitive Difficulties
No full textThe digitalization has changed the work life and created new cognitive demands that can be challenging to manage in digital work and everyday life for people with cognitive difficulties related to neurological disorders. Nevertheless, the consequences of these changes are largely unexplored. Thus, the overall aim of this thesis is to enhance knowledge of how people with cognitive difficulties experience digital work and other occupations in everyday life, and how to promote a sustainable digital work life. The thesis comprises four qualitative studies. Study I explored and described how people with cognitive difficulties engaged in digital work, experienced their vocational situation and how it influenced their everyday life. This study was designed as a qualitative, descriptive, multiple case study. Data were collected through semi-structured interviews, self-reports and assessments from seven participants with neurological disorders and analysed using pattern matching. The findings suggest that performing digital work was cognitively demanding and influenced engagement in other valuable occupations. Work-related obligations were prioritized over other occupations in everyday life. Additionally, digital work was facilitated by support from employers and family, as well as by using self-initiated management strategies in challenging situations. Study II described how people with cognitive difficulties due to neurological disorders experienced their use of self-initiated strategies to manage digitalized work and other occupations in everyday life. Eleven participants participated in qualitative interviews, supported by a dialogue support tool. The findings of the qualitative content analysis imply that self-initiated management strategies were often crucial for managing challenging situations in digital work and to uphold engagement in occupations outside work. Having an ability to self-evaluate and reflect upon the use of strategies was necessary for a conscious, flexible and effective use. Study III described employer representatives’ experiences of work environment management focusing on employees with cognitive difficulties working in a digital environment. Focus group discussions with six employer representatives were utilised for data collection. The focus group analysis indicated that aligning the work abilities of employees with cognitive difficulties to the evolving cognitive demands of digital work, was a continuous process. Given the dynamic nature of both employee’s abilities and work demands, fostering a trustful relationship and collaboration with the employee was crucial. This ongoing process required knowledge of digital technologies, the impact of cognitive difficulties on work ability and support from and collaboration with other professionals with related expertise. Study IV, explored and described how an internet-based occupational therapy intervention can support self-management in people with cognitive difficulties performing digital work and other occupations in everyday life. The study was designed as a qualitative, descriptive, case study. Data were collected at three occasions from four people with neurological disorders participating in the intervention ”Strategies for Empowering activities in Everyday life” [SEE 2.0.]. Data gathered through semi-structured interviews, self-reports and assessments were analysed using pattern matching. The findings suggest that SEE 2.0 has the potential to support the development of self-management and initiate a process of change in people with cognitive difficulties, thus having the possibility to facilitate a sustainable digital work and everyday life. The enhanced understanding derived from this thesis can be used to develop vocational rehabilitation for people with cognitive difficulties in digital work. Taking a wider approach when evaluating and identifying cognitive difficulties and considering work and other occupations as an entirety rather than separate parts, is vital. This to facilitate sustained engagement in digital work and a balanced everyday life. It is also essential to have continuous supportive collaboration between employees and employers, as abilities and demands are in constant interaction and change in digital work. Finally, the thesis emphasizes the importance of utilising each person's own resources and strategies to empower self-management, to promote a sustainable digital work life
Smartbands and Behavioural Interventions in the Classroom : Multimodal Learning Analytics Stress-Level Visualisations for Primary Education Teachers
No full textStudents’ stress levels may affect their well-being, attentiveness and learning outcomes in primary education classrooms. Positive behavioural interventions and support actions conducted by teachers may alleviate students’ stress levels, especially when addressing special educational needs. In this multimodal learning analytics study, students in a classroom were all given a smartband for their wrist during regular curriculum activities. Data comprised the semester of a single subject as a part of a research project conducted in Sweden. Biobehavioural stress-related arousal of students’ autonomic nervous system was visualised and analysed through distinguished behavioural modes. Additional data include naturalistic observational notes and two short teacher interviews. Research methodology and strategies for innovative implementation were presented and discussed alongside contextual details. For example, stress-level visualisations can aid actionable adjustments of behavioural intervention intensity and provide students’ attentiveness overview for teachers that sequence curricular activities during planning. Findings show an interdisciplinary basis for cost effective real-time dynamic solutions that involve visual dashboards with advantages to understanding student learning, both at a school-wide system level and for the classroom, if viewed optimistically. However, research on the topic is still in its infancy, notably with ethical risks as a growing pain