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1.
  • Jansson, Anna, et al. (författare)
  • Magnetron sputtering of the high entropy alloy CoCrFeMnNi on 316L : Influence of substrate grain orientations
  • 2023
  • Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 466
  • Tidskriftsartikel (refereegranskat)abstract
    • This study explores the influence of a 316L stainless steel substrate on the magnetron sputtering of the Cantor alloy CoCrFeMnNi at different substrate bias. The study was carried out on a polycrystalline 316L substrate where the growth behavior of the coating could be investigated on grains with different orientations. By combining electron backscatter diffraction (EBSD) before and after deposition and characterization of the same area, it was possible to determine growth behaviour and surface morphologies on individual substrate grains. No strong influence of the substrate was observed at a floating bias. At a bias of -100V, however, the coating was strongly influenced by the orientation of the individual substrate grains.  Epitaxial coating grains with a smooth surface were observed on the [102]-oriented grains while a more columnar growth was observed on [111]-oriented grains.  Furthermore, a small difference in growth rate was observed on different substrate orientations. The growth behaviour could be related to differences in surface energies and diffusion rates on different surface orientations.
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2.
  • Adolfsson, Johanna, 1986- (författare)
  • A new storm over the Naqab : The temporality of space in Israeli settler colonialism
  • 2023
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • How can a posthumanist conceptualization of landscape, one that embraces temporality and practice, help us to better understand contemporary settler colonialism? This thesis explores this proposition through its analyses of the desire of the Israeli state to ‘settle’ the Naqab. The Naqab, an area located in the south of modern-day Israel and within its borders, is continuously narrated as under threat of being lost to the Palestinian Bedouins. In contrast to the breadth of scholarly attention given to the occupied Palestinian Territories, there is a relative paucity of studies focusing on the Naqab and on the Palestinian citizens of Israel living therein. Inspired by the concept of taskscape and, more broadly, by a posthumanist political ecology approach, in this thesis I seek to remedy the determinist undertones quite often found in settler colonial studies.The thesis’ empirical data draw from qualitative methods and field research in the Naqab, undertaken during multiple field visits between the 2018 and 2021. The thesis comprises a comprehensive summary (kappa) and three research papers. In Paper 1, I show how a schism between the Jewish National Fund and the civil society green movement surfaced amid land conflicts between the state and Bedouin villagers east of Beersheva. I argue that this schism offers insights into how nature is negotiated in relation to environmentalism and Zionist ideology.  Further, I discuss how these negotiations point to an emerging new self-image of a post-settlement state that has abandoned pioneering, and replaced it with a planted forest (and natural) landscape as an emblem for Zionist nature. In Paper 2, I focus my attention on a network of Jewish villages in the Naqab. Based on a discourse analysis of YouTube videos produced by two Zionist organizations, I show how the narrative of Jewish relocation to the Naqab encompasses a modern re-enactment of the pioneering ideal, one mediated by a new neoliberal ethos of Israel as a ‘start-up nation’ and the Naqab as a new Israeli tech-hub. Finally, in Paper 3, I trace the cultural and political context of forest grazing in the Naqab. I argue that while the state uses afforestation as a proxy for territorialization, the irony is that it is the Bedouins who are largely responsible for everyday management of these forest areas, as grazing is a cost-effective method for keeping shrubs and other undergrowth low. I argue that in trying to accommodate grazing in the forest, policy makers struggle to juggle Bedouin land claims via continuous use and cultural connection to the land. Throughout the papers I affirm the performance of Israeli settler colonialism through the making of the natural environment. I assert that the tendency towards forest and grazing regulation, also articulated in planning policy, represents a move beyond the ‘era of pioneering’ towards a more formal type of society.  I conclude by contending that the multiple spaces and temporalities presented in the paper’s case studies are indicative of contradictory narratives in the portrayal of the Naqab is and thus assemble as a necessity of the settlement ambition.
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3.
  • Alvi, Sajid Ali (författare)
  • Refractory High Entropy Alloys and Films for High Temperature Applications
  • 2020
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • High-entropy alloy (HEA) is a multi-component alloy constituting five or more principal elements in equi- or near equi-atomic percentages. The high configurational entropy in a HEA composition, in contrast to conventional alloys, leads to the stabilisation of the alloying elements in stable solid solutions of face-centred-cubic (FCC), body-centred-cubic (BCC) and/or amorphous structures. The characteristic properties of HEAs are mainly governed by lattice distortion, sluggish diffusion and entropy- and cocktail-effects. Refractory high-entropy alloys (RHEAs), consisting of refractory elements, are considered as a paradigm shift in developing materials for high temperature applications.The current PhD project investigates four different aspects of RHEAs. First, it involves developing CuMoTaWV RHEA by spark plasma sintering (SPS) and utilising the cocktail effect of HEAs for high temperature tribological application. The use of the cocktail effect, defined as selecting favourable compositions for particular applications, is utilised for RHEA compositions in order to yield adaptive tribological behaviour at changing temperatures or environments. The sintered CuMoTaWV showed formation of BCC solid solution and a composite microstructure. The high temperature tribological investigations showed an adaptive behaviour at different temperatures. At lower temperatures Cu lowered the wear rate through formation of CuO, and at higher temperatures V enhanced the tribological resistance through formation of lubricating V2O5 phases.The second aspect involves studying the effect of lattice distortion on mechanical properties of magnetron sputtered thin film after adding Cu to the refractory elements of Mo, Ta, W and V. A target of CuMoTaWV was developed through partial sintering and used to deposit thin film on different substrates. The deposited film showed formation of BCC solid solution, which was verified through DFT calculations. The lattice distortion in CuMoTaWV film showed high hardness and nano-pillar compressive strength. Furthermore, the tribological properties were enhanced at temperatures up to 400oC due to the addition of Cu.The third aspect involves studying the effect of configurational entropy on the formation and high temperature stability of refractory high-entropy thin film metallic glass and its nitrides, by increasing the number of principal elements. A partially sintered target of TiVZrNbMoHfTaW was used to deposit thin films of metallic glass and nitrides through magnetron sputtering. The metallic glass thin films and its nitrides were found to have high hardness of 7.3 GPa and 19–43 GPa, respectively. Furthermore, the metallic glass thin films showed a high nano-pillar compressive strength of up to 3 GPa, almost twice as high as conventional metallic glass films. The phase stability of metallic glass and its nitride thin films were found to be stable at temperatures up to 750oC and 950oC, respectively. The exceptionally superior mechanical properties and high temperature stability has been attributed to the presence of high configurational entropy. The last part of this PhD thesis consists of studying high-entropy-based W-rich alloys for high temperature applications. A W-based alloy of composition W0.5(TaTiVCr)0.5 was consolidated using SPS. The resulting alloy revealed a BCC solid solution structure. The microstructure of W-rich alloys consist of a combination of W-rich, high-entropy and TiC phases. The BCC solid solution structure in W-rich alloys was found to be stable with exceptionally high compressional strength up to 1,400oC. A high compressive yield strength of 1136 ± 40 MPa, 830 ± 60 MPa and 425 ± 15 MPa was found at test temperatures of 1,000oC, 1,200oC and 1,400oC, respectively. The resulting high strength has been related to the formation of high-entropy phases, which in return induces sluggish diffusion at higher temperatures. The high temperature tribology at 400oC showed an average COF and low wear rate of 0.5 and 1.37 x 10-5 mm3/Nm, respectively. The high temperature wear resistance at 400oC was enhanced due to the presence of HEA and TiC phases. The studies carried out in this thesis suggest the possibility of utilising the full potential of the cocktail effect, lattice distortion and configurational entropy in designing new high-entropy compositions for applications requiring adaptive tribological behaviour, superior mechanical properties and high temperature phase stability.
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4.
  • Andersson, Ulf Bertil, et al. (författare)
  • Emendment to the term complex in: “Guide for geological nomenclature in Sweden” (Kumpulainen 2016)
  • 2022
  • Ingår i: GFF. - : Taylor & Francis. - 1103-5897 .- 2000-0863. ; 144:3-4, s. 151-151
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Since the publication of Kumpulainen (2016), the Committeehave been alerted by the investigation and subsequent changesto the North American Stratigraphic Code concerning thelithodemic unit“complex”(Easton et al.2016; North Ameri-can Commission on Stratigraphic Nomenclature (NACSN)2017). These changes concern the introduction of the nomen-clature unit“Intrusive Complex”. In the original version(NACSN1983), as well as in the Swedish Guide for nomencla-ture (Kumpulainen2016), the unit“complex”is defined ascontaining at least two genetic classes of rocks, i.e., igneous,sedimentary, or metamorphic.
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5.
  • Askenmalm, Fredrika (författare)
  • Hur mjölk i tanken blir kronor på banken : Bondförnuftets rationalitet
  • 2024
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Lantbrukare har under senare år ofta hörts framföra klagomål om att den administrativa bördan blivit allt tyngre vad gäller rapportering och ansökningar som ska göras till olika myndigheter. Tidigare forskning framställer det som att den administrativa bördan skulle kunna utsträckas till att också gälla redovisning, så som bokföring, kalkylering och budgetering. Detta då det beskrivs som att lantbrukare varken förstår eller använder redovisning för att sköta sitt lantbruk. Tidigare forskning tycks dock bortse från att lantbrukare ofta tillämpar en annan form av logik än den som förutsätts gälla inom redovisningsforskning. Det verkar också förutsättas att lantbrukarna ska kunna förstå och använda den redovisningsterminologi som finns inom forskningsvärlden trots att lantbrukarna ofta saknar utbildning inom redovisning. Mot denna bakgrund undersöker denna avhandling hur lantbrukare förstår och använder redovisning.Avhandlingen bygger på det grundläggande teoretiska perspektivet att se redovisning som ett språk för att på detta sätt förklara lantbrukarnas förståelse av redovisning. Avhandlingen bygger vidare på familjeföretagsforskning, speciellt socioemotional wealth (SEW), och beslutsteori för att förklara lantbrukarnas användning av redovisningsinformation.Den empiriska studien är inspirerad av grundad teori. Det empiriska materialet utgörs främst av intervjuer med mjölkbönder i Jönköpings län. Även intervjuer med rådgivare och bankmän och vissa sekundärdata har utgjort underlag för avhandlingen.Resultatet av undersökningen visar att lantbrukare har större kunskaper vad gäller redovisning än vad tidigare forskning indikerat. Delvis kan detta förklaras av att lantbrukare använder en annan terminologi än vad som vanligtvis används inom redovisningsforskning när de beskriver redovisning. Mjölkföretag drivs vanligen som familjeföretag och denna avhandling visar på en mycket stark familjeförankring i dessa företag. Det innebär att mjölkföretag ibland (speciellt vad gäller fastigheten) prioriterar annat än finansiella mål, vilket ofta kopplas samman med en intuitiv beslutsstil. Inom redovisning förutsätts generellt att finansiella mål är eftersträvansvärda. Lantbrukarnas sätt att se på redovisning påverkar också hur den används. Även om de förstår och använder redovisning är det inte säkert att den används på det mest vinstmaximerande sättet. I stället kan SEW vara det som prioriteras. Användning av redovisning anpassas efter den situation lantbrukaren befinner sig i. Vissa delar av redovisningen ses och förstås som speglingar av verkligheten eller som framåtriktade ledtrådar. När lantbrukare förstår redovisningen på så vis, uppfattas den som användbar för beslutsfattande. Andra delar av redovisningen ses som regelföljande, eller ibland till och med som helt frikopplad från själva verksamheten. Detta gäller framför allt redovisning till Skatteverket och Jordbruksverket. Dessa redovisningar används inte för beslut, men de är ändå rationellt utformade för att uppnå bästa möjliga utfall (skatteutjämning eller jordbruksstöd).
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6.
  • Backman, Helena, et al. (författare)
  • Decreased COPD prevalence in Sweden after decades of decrease in smoking
  • 2020
  • Ingår i: Respiratory Research. - : Springer Nature. - 1465-9921 .- 1465-993X. ; 21
  • Tidskriftsartikel (refereegranskat)abstract
    • BackgroundCOPD has increased in prevalence worldwide over several decades until the first decade after the millennium shift. Evidence from a few recent population studies indicate that the prevalence may be levelling or even decreasing in some areas in Europe. Since the 1970s, a substantial and ongoing decrease in smoking prevalence has been observed in several European countries including Sweden. The aim of the current study was to estimate the prevalence, characteristics and risk factors for COPD in the Swedish general population. A further aim was to estimate the prevalence trend of COPD in Northern Sweden from 1994 to 2009.MethodsTwo large random population samples were invited to spirometry with bronchodilator testing and structured interviews in 2009–2012, one in south-western and one in northern Sweden, n = 1839 participants in total. The results from northern Sweden were compared to a study performed 15 years earlier in the same area and age-span. The diagnosis of COPD required both chronic airway obstruction (CAO) and the presence of respiratory symptoms, in line with the GOLD documents since 2017. CAO was defined as post-bronchodilator FEV1/FVC < 0.70, with sensitivity analyses based on the FEV1/FVC < lower limit of normal (LLN) criterion.ResultsBased on the fixed ratio definition, the prevalence of COPD was 7.0% (men 8.3%; women 5.8%) in 2009–2012. The prevalence of moderate to severe (GOLD ≥ 2) COPD was 3.5%. The LLN based results were about 30% lower. Smoking, occupational exposures, and older age were risk factors for COPD, whereof smoking was the most dominating risk factor. In northern Sweden the prevalence of COPD, particularly moderate to severe COPD, decreased significantly from 1994 to 2009, and the decrease followed a decrease in smoking.ConclusionsThe prevalence of COPD has decreased in Sweden, and the prevalence of moderate to severe COPD was particularly low. The decrease follows a major decrease in smoking prevalence over several decades, but smoking remained the dominating risk factor for COPD.
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7.
  • Berastegui, Pedro, et al. (författare)
  • Magnetron Sputtering of Nanolaminated Cr2AlB2
  • 2020
  • Ingår i: Coatings. - : MDPI. - 2079-6412. ; 10:8
  • Tidskriftsartikel (refereegranskat)abstract
    • A ternary Cr(2)AlB(2)phase was deposited as a film using magnetron sputtering. Its anisotropic structure displays both structural and chemical similarities with the nanolaminated MAX phases (M(n+1)AX(n)(n = 1-3) where M usually is an early transition metal, A is typically an element in group 13-14 and X is C or N), and can be described as CrB slabs separated by layers of Al. Combinatorial sputtering was used to optimise the sputtering process parameters for films with the Cr(2)AlB(2)composition. The influences of substrate, temperature and composition were studied using X-ray diffraction, X-ray photoelectron spectroscopy and electron microscopy. Films deposited at room temperature were X-ray amorphous but crystalline films could be deposited on MgO substrates at 680 degrees C using a composite Al-B, Cr and Al targets. X-ray diffraction analyses showed that the phase composition and texture of the films was strongly dependent on the chemical composition. Films with several phases or with a single Cr(2)AlB(2)phase could be deposited, but an additional Al target was required to compensate for a loss of Al at the high deposition temperatures used in this study. The microstructure evolution during film growth was strongly dependent on composition, with a change in texture in Al-rich films from a preferred [010] orientation to a [100]/[001] orientation. A model based on Al desorption from the surface of the growing grains is proposed to explain the texture variations.
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8.
  • Calles, Britt-Marie, et al. (författare)
  • Grunddatadomän transportsystem: Kompletterande underlag till den utforskande förstudien
  • 2022
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • I mars 2022 levererade Trafikverket och samverkande myndigheter (Transportstyrelsen, Sjöfartsverket, Luftfartsverket, Trafikanalys och VTI, Statens väg- och transportforskningsinstitut) en rapport som sammanfattade den utforskande utvecklingen att utreda en grunddatadomän för transportsystemet.  Föreliggande rapport är en komplettering till den ursprungliga rapporten och utgör Trafikverkets inklusive samverkande myndigheters sammantagna underlag (utforskande utveckling) för etablering av en grunddatadomän för transportsystemet. Arbetet har bedrivits under ledning av Myndigheten för digital förvaltning (DIGG) med Trafikverket som ansvarig för den utforskande utvecklingen. Till rapporten hör en bilaga, se länk till höger.Ursprunglig rapport: Grunddatadomän transportsystem: Samverkansuppdrag mellan transportmyndigheterna för att bedriva en utforskande utveckling att utreda en grunddatadomän för information kopplat till transportsystemet
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9.
  • Casillas Trujillo, Luis, et al. (författare)
  • Experimental and theoretical evidence of charge transfer in multi-component alloys : how chemical interactions reduce atomic size mismatch
  • 2021
  • Ingår i: Materials Chemistry Frontiers. - : Royal Society of Chemistry. - 2052-1537. ; 5:15, s. 5746-5759
  • Tidskriftsartikel (refereegranskat)abstract
    • Ab initio simulations of a multi-component alloy using density functional theory (DFT) were combined with experiments on thin films of the same material using X-ray photoelectron spectroscopy (XPS) to study the connection between the electronic and atomic structures of multi-component alloys. The DFT simulations were performed on an equimolar HfNbTiVZr multi-component alloy. Structure and charge transfer were evaluated using relaxed, non-relaxed, as well as elemental reference structures. The use of a fixed sphere size model allowed quantification of charge transfer, and separation into different contributions. The charge transfer was generally found to follow electronegativity trends and results in a reduced size mismatch between the elements, and thus causes a considerable reduction of the lattice distortions compared to a traditional assumption based on tabulated atomic radii. A calculation of the average deviation from the average radius (i.e. the so-called δ-parameter) based on the atomic Voronoi volumes gave a reduction of δ from ca. 6% (using the volumes in elemental reference phases) to ca. 2% (using the volumes in the relaxed multi-component alloy phase). The reliability of the theoretical results was confirmed by XPS measurements of a Hf22Nb19Ti18V19Zr21 thin film deposited by sputter deposition. The experimentally observed core level binding energy shifts (CLS), as well as peak broadening due to a range of chemical surroundings, for each element showed good agreement with the calculated DFT values. The single solid solution phase of the sample was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) including energy dispersive spectroscopy (EDS) with nm-resolution. These observations show that the HfNbTiVZr solid solution phase is non-ideal, and that chemical bonding plays an important part in the structure formation, and presumably also in the properties. Our conclusions should be transferable to other multi-component alloy systems, as well as some other multi-component material systems, and open up interesting possibilities for the design of material properties via the electronic structure and controlled charge transfer between selected metallic elements in the materials.
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10.
  • Casillas Trujillo, Luis, et al. (författare)
  • Interstitial carbon in bcc HfNbTiVZr high-entropy alloy from first principles
  • 2020
  • Ingår i: Physical Review Materials. - : AMER PHYSICAL SOC. - 2475-9953. ; 4:12
  • Tidskriftsartikel (refereegranskat)abstract
    • The remarkable mechanical properties of high-entropy alloys can be further improved by interstitial alloying. In this work we employ density functional theory calculations to study the solution energies of dilute carbon interstitial atoms in tetrahedral and octahedral sites in bcc HfNbTiVZr. Our results indicate that carbon interstitials in tetrahedral sites are unstable, and the preferred octahedral sites present a large spread in the energy of solution. The inclusion of carbon interstitials induces large structural relaxations with long-range effects. The effect of local chemical environment on the energy of solution is investigated by performing a local cluster expansion including studies of its correlation with the carbon atomic Voronoi volume. However, the spread in solution energetics cannot be explained with a local environment analysis only pointing towards a complex, long-range influence of interstitial carbon in this alloy.
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11.
  • Chou, Chia-Ying, et al. (författare)
  • Precipitation Kinetics During Post-heat Treatment of an Additively Manufactured Ferritic Stainless Steel
  • 2022
  • Ingår i: Metallurgical and Materials Transactions. A. - : Springer Nature. - 1073-5623 .- 1543-1940. ; 53:8, s. 3073-3082
  • Tidskriftsartikel (refereegranskat)abstract
    • The microstructure response of laser-powder bed fusion (L-PBF)-processed ferritic stainless steel (AISI 441) during post-heat treatments is studied in detail. Focus is on the precipitation kinetics of the Nb-rich phases: Laves (Fe2Nb) and the cubic carbo-nitride (NbC), as well as the grain structure evolution. The evolution of the precipitates is characterized using scanning and transmission electron microscopy (SEM and TEM) and the experimental results are used to calibrate precipitation kinetics simulations using the precipitation module (TC-PRISMA) within the Thermo-Calc Software package. The calculations reproduce the main trend for both the mean radii for the Laves phase and the NbC, and the amount of Laves phase, as a function of temperature. The calibrated model can be used to optimize the post-heat treatment of additively manufactured ferritic stainless steel components and offer a creator tool for process and structure linkages in an integrated computational materials engineering (ICME) framework for alloy and process development of additively manufactured ferritic steels.
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12.
  • Fritze, Stefan, et al. (författare)
  • Elemental distribution and fracture properties of magnetron sputtered carbon supersaturated tungsten films
  • 2024
  • Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 477
  • Tidskriftsartikel (refereegranskat)abstract
    • The combination of strength and toughness is a major driving force for alloy design of protective coatings, and nanocrystalline tungsten (W)-alloys have shown to be promising candidates for combining strength and toughness. Here we investigate the elemental distribution and the fracture toughness of carbon (C) alloyed W thin films prepared by non-reactive magnetron sputtering. W:C films with up to ~4 at.% C crystallize in a body-centered-cubic structure with a strong 〈hh0〉texture, and no additional carbide phases are observed in the diffraction pattern. Atom probe tomography and X-ray photoelectron spectroscopy confirmed the formation of such a supersaturated solid solution. The pure W film has a hardness ~13 GPa and the W:C films exhibit a peak hardness of ~24 GPa. In-situ micromechanical cantilever bending tests show that the fracture toughness decreases from ~4.5 MPa·m1/2 for the W film to ~3.1 MPa·m1/2 for W:C films. The results show that C can significantly enhance the hardness of W thin films while retaining a high fracture toughness.
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13.
  • Fritze, Stefan, et al. (författare)
  • Influence of Carbon on Microstructure and Mechanical Properties of Magnetron Sputtered TaW Coatings
  • 2020
  • Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 196
  • Tidskriftsartikel (refereegranskat)abstract
    • (Ta,W) and (Ta,W):C films with-5 at.% C were deposited by non-reactive magnetron sputtering. They crystallised in a bcc structure with a columnar microstructure. The solid solubility of C in (Ta,W) alloys is very low, which suggests that the (Ta,W):C films are supersaturated with respect to carbon. This was confirmed by diffraction and atom probe tomography (APT) showing that carbon is in the as-deposited (Ta,W):C films homogeneously distributed in the structure without carbide formation or carbon segregation. Annealing at 900 degrees C for 2 h showed no significant column coarsening but an increased defect density at the column boundaries in the (Ta,W):C films. The films were still supersaturated with respect to carbon but APT showed a partial segregation of carbon presumably to defect-rich column boundaries after annealing. The (Ta,W) films exhibited a hardness of-12-13 GPa. Alloying with carbon increased the hardness to-17 GPa. The hardness increased to-19 GPa for the annealed (Ta,W):C films. This annealing-induced hardness increase was explained by C segregation to the more defect-rich column boundaries, which restricts dislocation movements. (Ta,W):C coatings may be a potential alternative to ceramic coatings, worth exploring further by small scale mechanical testing to investigate if these materials are ductile.
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14.
  • Fritze, Stefan, et al. (författare)
  • Magnetron sputtering of carbon supersaturated tungsten films-A chemical approach to increase strength
  • 2021
  • Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 208
  • Tidskriftsartikel (refereegranskat)abstract
    • Tungsten (W)-based materials attract significant attention due to their superior mechanical properties. Here, we present a chemical approach based on the addition of carbon (C) for increased strength via the combination of three strengthening mechanisms in W thin films. W:C thin films with C concentrations up to-4 at.% were deposited by magnetron sputtering. All films exhibit a body-centred-cubic structure with strong texture and columnar growth behaviour. X-ray and electron diffraction measurements suggest the formation of supersaturated W:C solid solution phases. The addition of C reduced the average column width from-133 nm for W to-20 nm for the film containing-4 at.% C. The column refinement is explained by a mechanism where C acts as re-nucleation sites. The W film is-13 GPa hard, while the W:C films achieve a peak hardness of-24 GPa. The W:C films are-11 GPa harder than the W film, which is explained by a combination of grain refinement strengthening, solid solution strengthening and increased dislocation density. Additional micropillar compression tests showed that the flow stress increased upon C addition, from-3.8 to-8.3 GPa and no brittle fracture was observed.
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15.
  • Fritze, Stefan (författare)
  • Microstructure and Mechanical Properties of Magnetron Sputtered Refractory Metal Thin Films
  • 2020
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The design and development of new multifunctional materials that exhibit a combination of high hardness and ductility, as well as a high corrosion resistance and thermal stability, is one of the key challenges in the field of material science. The focus of this thesis is on the development of novel multifunctional magnetron sputtered CrNbTaTiW–C based thin films. Carbon was selected as an alloying element to investigate if it could modify the microstructure (via grain refinement) and improve the properties (e.g. the hardness and ductility).TaW-rich and near-equimolar high entropy alloys in the CrNbTaTiW system were selected as starting points for this study. The latter alloys were predicted, based on empirical design rules, to form a single-phase solid solution. In contrast, thermodynamic calculations showed that the films at equilibrium should be composed of a mixture of several phases at temperatures below 1100 °C.  Experimentally, however, a single-phase bcc structure was observed for the deposited films and it was concluded that the films were kinetically and not entropy stabilised. A hypothesis is that the kinetics during sputtering allow a ’direct’ phase selection by tuning the process parameters and evidence of this was found in the HfNbTiVZr alloy system.The CrNbTaTiW–C system is, however, complex and additional studies were carried out on the W–C and TaW–C systems. All metallic films crystallised in a bcc structure with a <110> texture and the column width of these films varied between 25 nm and 80 nm. The films were very hard (~ 13 GPa), which was explained by the small grain size. A single-phase bcc structure was also obtained upon the addition of 5-10 at.% carbon for all compositions except the near-equimolar CrNbTaTiW. X-ray diffraction indicated a unit cell expansion, which was attributed to the formation of a supersaturated solid solution. Additional atom probe tomography (APT) studies on selected samples confirmed the formation of such solid solutions. The supersaturated solid solution is not thermodynamically stable and an annealing study showed that heat treatment yielded segregation and clustering of carbon at the grain boundaries. The addition of carbon had a grain refining effect in the W–C system and the multicomponent CrNbTaTiW–C system. In general, the addition of carbon increased the hardness, which was mainly caused by a reduced grain size in line with the Hall-Petch relationship. Excellent mechanical properties of carbon supersaturated films were further confirmed in pillar tests on W–C films, which showed very high yield strength (~ 9 GPa) and no brittle fracture. The results show that carbon can be used as a chemical approach to control the grain size and properties of these films. Multicomponent carbides with a B1 structure were formed at high carbon concentrations (~ 40 at.%). The microstructure of these films depended strongly on the process parameters and a higher deposition temperature was found to increase the film density and hardness. The TaW-rich carbide exhibited a very high hardness of ~ 35 GPa and excellent corrosion resistance.
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16.
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17.
  • Gennemark, Peter, et al. (författare)
  • An oral antisense oligonucleotide for PCSK9 inhibition
  • 2021
  • Ingår i: Science Translational Medicine. - : AMER ASSOC ADVANCEMENT SCIENCE. - 1946-6234 .- 1946-6242. ; 13:593
  • Tidskriftsartikel (refereegranskat)abstract
    • Inhibitors of proprotein convertase subtilisin/kexin type 9 (PCSK9) reduce low-density lipoprotein (LDL) cholesterol and are used for treatment of dyslipidemia. Current PCSK9 inhibitors are administered via subcutaneous injection. We present a highly potent, chemically modified PCSK9 antisense oligonucleotide (ASO) with potential for oral delivery. Past attempts at oral delivery using earlier-generation ASO chemistries and transient permeation enhancers provided encouraging data, suggesting that improving potency of the ASO could make oral delivery a reality. The constrained ethyl chemistry and liver targeting enabled by N-acetylgalactosamine conjugation make this ASO highly potent. A single subcutaneous dose of 90 mg reduced PCSK9 by >90% in humans with elevated LDL cholesterol and a monthly subcutaneous dose of around 25 mg is predicted to reduce PCSK9 by 80% at steady state. To investigate the feasibility of oral administration, the ASO was coformulated in a tablet with sodium caprate as permeation enhancer. Repeated oral daily dosing in dogs resulted in a bioavailability of 7% in the liver (target organ), about fivefold greater than the plasma bioavailability. Target engagement after oral administration was confirmed by intrajejunal administration of a rat-specific surrogate ASO in solution with the enhancer to rats and by plasma PCSK9 and LDL cholesterol lowering in cynomolgus monkey after tablet administration. On the basis of an assumption of 5% liver bioavailability after oral administration in humans, a daily dose of 15 mg is predicted to reduce circulating PCSK9 by 80% at steady state, supporting the development of the compound for oral administration to treat dyslipidemia.
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18.
  • Goetz, Inga K., 1992-, et al. (författare)
  • Convective Flow Redistribution of Oxygen by Laser Melting of a Zr-Based Amorphous Alloy
  • 2023
  • Ingår i: Materials. - : MDPI. - 1996-1944. ; 16:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxygen impurities play a crucial role in the glass-forming ability and crystallisation behaviour of metallic glasses. In the present work, single laser tracks were produced on Zr59.3-xCu28.8 Al10.4Nb1.5Ox substrates (x = 0.3, 1.3) to study the redistribution of oxygen in the melt pool under laser melting, which provides the basis for laser powder bed fusion additive manufacturing. Since such substrates are commercially not available, they were fabricated by arc melting and splat quenching. X-ray diffraction revealed that the substrate with 0.3 at.% oxygen was X-ray amorphous, while the substrate with 1.3 at.% oxygen was partially crystalline. Hence, it is evident that the oxygen content affects the crystallisation kinetics. Subsequently, single laser tracks were produced on the surface of these substrates, and the melt pools attained from the laser processing were characterised by atom probe tomography and transmission electron microscopy. Surface oxidation and subsequent convective flow redistribution of oxygen by laser melting were identified as causes of the presence of CuOx and crystalline ZrO nanoparticles in the melt pool. Bands of ZrO likely originate from surface oxides that were moved deeper into the melt pool by convective flow. The findings presented here highlight the influence of oxygen redistribution from the surface into the melt pool during laser processing.
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19.
  • Goetz, Inga Katharina, 1992- (författare)
  • Local structure and composition : in additively manufactured bulk metallic glasses and composites
  • 2023
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Additive manufacturing enables the production of complex multi-material geometries and bulk metallic glass parts beyond their critical casting thickness. The local modification of structure, composition, and properties is explored in this thesis with the aim to design novel composite materials and functional gradients. The present work contributes to the process understanding required to produce bulk metallic glass composites in the laser powder bed fusion process. The investigated material systems include zirconium and iron based metallic glasses, metallic glass - nitride composites, as well as laser nitriding of titanium.The onset of devitrification of metallic glasses due to the processing or post-processing heat treatments induces the formation of nanoscale clusters. Features of > 1 nm can be detected and reliably distinguished from random fluctuations by atom probe tomography. The progression of crystallisation depends on the oxygen content of the samples and the applied heating or cooling rates. In-depth understanding of the crystallisation processes can be used to optimise both compositions and processing conditions. The process atmosphere contains reactive species such as oxygen or nitrogen, which can be incorporated during different stages of processing by surface oxidation of the powder or substrate pieces as well as by reactions with the gas during processing. While an inert gas atmosphere with a low residual oxygen content is sufficient to hinder reactions with residual oxygen, a nitrogen atmosphere can be used for local laser nitriding and, thus, the fabrication of metallic glass – ceramic composites. Due to the decompositions of nitrides formed in the preceding process steps and the tendency of a metallic glass matrix to crystallise, which limits the processing conditions, the incorporation of nitrogen is restricted to the first few hundred nm from the surface for a Zr-based amorphous alloy. In titanium, as a crystalline example, nitrogen is incorporated throughout the molten pool.The nitride composites exhibit increased hardness depending on the local nitride fraction, which can thus be used to fabricate specific property gradients within or on a printed piece. With optimised process parameters, the amorphous fraction of a printed Fe-based bulk metallic glass can be tailored for improved soft magnetic properties.
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20.
  • Gustafsson Bragde, Hanna, 1979-, et al. (författare)
  • Characterisation of gene and pathway expression in stabilised blood from children with coeliac disease
  • 2020
  • Ingår i: BMJ open gastroenterology. - : BMJ. - 2054-4774. ; 7:1
  • Tidskriftsartikel (refereegranskat)abstract
    • INTRODUCTION: A coeliac disease (CD) diagnosis is likely in children with levels of tissue transglutaminase autoantibodies (anti-TG2) >10 times the upper reference value, whereas children with lower anti-TG2 levels need an intestinal biopsy to confirm or rule out CD. A blood sample is easier to obtain than an intestinal biopsy sample, and stabilised blood is suitable for routine diagnostics because transcript levels are preserved at sampling. Therefore, we investigated gene expression in stabilised whole blood to explore the possibility of gene expression-based diagnostics for the diagnosis and follow-up of CD.DESIGN: We performed RNA sequencing of stabilised whole blood from active CD cases (n=10), non-CD cases (n=10), and treated CD cases on a gluten-free diet (n=10) to identify diagnostic CD biomarkers and pathways involved in CD pathogenesis.RESULTS: No single gene was differentially expressed between the sample groups. However, by using gene set enrichment analysis (GSEA), significantly differentially expressed pathways were identified in active CD, and these pathways involved the inflammatory response, negative regulation of viral replication, translation, as well as cell proliferation, differentiation, migration, and survival. The results indicate that there are differences in pathway regulation in CD, which could be used for diagnostic purposes. Comparison between GSEA results based on stabilised blood with GSEA results based on small intestinal biopsies revealed that type I interferon response, defence response to virus, and negative regulation of viral replication were identified as pathways common to both tissues.CONCLUSIONS: Stabilised whole blood is not a suitable sample for clinical diagnostics of CD based on single genes. However, diagnostics based on a pathway-focused gene expression panel may be feasible, but requires further investigation.
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21.
  • Götz, Inga Katharina, 1992-, et al. (författare)
  • Reactive metal additive manufacturing : Surface near ZrN - metallic glass composite formation and mechanical properties
  • 2023
  • Ingår i: Additive Manufacturing. - : Elsevier. - 2214-8604 .- 2214-7810. ; 66
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • ZrN formation in a Zr-based bulk metallic glass is observed after processing using reactive laser powder bed fusion. Two processing routes employing nitrogen as a reactive process gas are explored: (1) Standard inert processing in argon followed by reactive remelting in nitrogen and (2) reactive processing in nitrogen. Incorporation of nitrogen is depth-dependent and both approaches result in a dispersion of ZrN nanocrystals in the amorphous matrix close to the surface. The process parameters can be adjusted to control the volume fraction of crystalline phases formed. Hence, it is shown that reactive additive manufacturing can be utilised to form bulk metallic glass-ceramic composites in surface near regions. Thereby we demonstrate that the reactive gas atmosphere utilised during additive manufacturing enables local tailoring of structure, composition, and mechanical properties in the vicinity of the surface.
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22.
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23.
  • Hellgren, Margareta, 1955, et al. (författare)
  • Circulating endothelin-1 levels are positively associated with chronic kidney disease in women but not in men: a longitudinal study in the Vara-Skovde cohort
  • 2021
  • Ingår i: Bmc Nephrology. - : Springer Science and Business Media LLC. - 1471-2369. ; 22:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Background The vasoconstricting peptide endothelin-1 (ET-1) is associated with endothelial dysfunction. The aim of this paper was to investigate whether circulating ET-1 levels predicts chronic kidney disease (CKD) in a prospective population study. Methods In 2002-2005, 2816 participants (30-74 years) were randomly selected from two municipalities in South-Western Sweden and followed up in a representative sample of 1327 individuals after 10 years. Endothelin-1 levels were assessed at baseline. Outcome was defined as CKD stage 3 or above based on eGFR < 60 mL/min/1.73m(2). Those 1314 participants with successful analysis of ET-1 were further analyzed using binary logistic regression. Results At follow-up, 51 (8%) men and 47 (7,8%) women had CKD stage 3 and above. Based on levels of ET-1 the population was divided into quintiles showing that women in the highest quintile (n = 132) had a significantly increased risk of developing CKD during the follow up period (OR = 2.54, 95% CI:1.19-5.45, p = 0.02) compared with the other quintiles (1-4). The association was borderline significant after adjusted for age, current smoking, alcohol consumption, hypertension, diabetes, BMI, high- sensitive CRP and LDL-cholesterol (OR = 2.25, 95% CI:0.97-5.24, p = 0.06). No significant differences were observed between quintiles of ET-1 and development of CKD in men (NS). Conclusions High levels of ET-1 are associated with development of CKD in women.
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24.
  • Hellgren, Margareta, 1955, et al. (författare)
  • Report from an effort to prevent type 2 diabetes development in primary care
  • 2021
  • Ingår i: Primary Care Diabetes. - : Elsevier BV. - 1751-9918. ; 15:2, s. 240-244
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: In a clinical trial 2009?2012, individuals with prediabetes were randomised to a lifestyle intervention (LI) focused on physical activity or care as usual (CAU), with the aim of reducing development of type 2 diabetes (T2DM). At study termination after three years, there was a significantly less of an increase in insulin resistance in LI compared with the CAU group. The aim of this extended follow-up was to investigate whether positive results concerning metabolic variables remained five years after study termination. Method: All participants from the original study were contacted for a new follow-up with an oral glucose tolerance test, anthropometric measurements, blood pressure and blood samples. Questionnaires about lifestyle were completed. Results: A total of 69 of the original 123 participants were examined, and personal data for another five participants were collected from the medical charts (n = 74). The LI group showed a decrease in diastolic blood pressure (?4 mmHg, CI 95% 0.8?6.8, p = 0.014) and body weight (?3 kg, CI 95% 1.2?4.9, p = 0.002) since base-line. Weight loss in the LI group was significantly greater compared with weight loss in the CAU group (?3 kg, CI 0.1?5.9, p = 0.044). Insulin resistance markers and incident T2DM were similar among the groups. Conclusion: Although without modifying the incidence of diabetes or the level of insulin resistance, a physical activity intervention may be used to induce sustainable weight change in subjects with prediabetes at the primary care level. ? 2020 The Author(s). Published by Elsevier Ltd on behalf of Primary Care Diabetes Europe. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).
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25.
  • Huang, Jing-Jia, 1990- (författare)
  • Surface-Controlled Chemical Vapor Deposition of Silicon Carbide
  • 2022
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Polycrystalline cubic silicon carbide, 3C-SiC, has long been investigated in the field of hard coating materials. The typical synthesis method for 3C-SiC coatings is thermal chemical vapor deposition (CVD) using either multicomponent precursors, e.g. methyltrichlorosilane, or a combination of single component precursors, e.g. silane and propane. In this thesis, the fabrication of polycrystalline SiC coatings has been explored from the new aspects on the basis of thermal CVD utilizing silicon tetrachloride (SiCl4) and various hydrocarbons, i.e. toluene (C7H8), methane (CH4) and ethylene (C2H4) as the precursors. The goal of this thesis is to control the surface chemistry in the SiCl4-based SiC CVD and has been accomplished by the following three different approaches: In the first approach to control the surface chemistry of SiC CVD, the difference in the adsorption energy of aromatic and aliphatic hydrocarbons on different SiC crystal planes was utilized. Under identical deposition conditions, a highly <111>-oriented 3C-SiC coating was deposited using C7H8 as the carbon precursor, whereas using CH4 resulted in a randomly oriented 3C-SiC. The results from quantum chemical calculation showed that the active film forming carbon species, i.e. C6H6 in the C7H8 process and CH3 in both C7H8 and CH4 processes, behaved differently when they adsorbed on the 3C-SiC (111) and (110) planes. CH3 is strongly chemisorbed on both planes, while C6H6 is chemisorbed on the (111) plane, but only physiosorbed on the other. The significant difference in the adsorption energy of CH3 and C6H6 on the (111) and (110) planes therefore explains the resulting highly <111>-oriented 3C-SiC from the C7H8 process. Furthermore, the ability to deposit 3C-SiC coatings with alternating highly <111>- and randomly oriented layers by merely switching the carbon precursor between C7H8 and CH4 or C2H4 in a single CVD deposition has further proven that the effect of aromatic hydrocarbons on the preferred growth orientation of 3C-SiC was controlled primarily by the surface chemistry.  The second approach to the surface-controlled SiC CVD was based on the reduction of surface reaction probability (β) for conformal film growth via low-temperature, low-pressure CVD, which was originally proposed by Abelson and Girolami. Their strategies in reducing β, including lowering the temperature and increasing the precursor partial pressure, were successfully adapted to the SiC CVD growth using SiCl4 and C2H4 as the precursors in this thesis, where an elevated temperature and a moderate pressure were used. Moreover, the addition of Cl species as a growth inhibitor to the process further reduced the β, leading to a superconformal SiC growth.  The third approach employed in this thesis for the SiC growth was pulsed CVD. Instead of a continuous and simultaneous SiCl4 and C2H4 flow, the precursors were pulsed alternately into the chamber with each precursor pulse being separated by a H2 purge. In this precursor delivery mode, the gas phase reactions between SiCl4 and C2H4 were avoided and hence the SiC growth was mostly controlled by the surface chemistry. Altering the pulse durations of the precursors led to a variation of growth per cycle (GPC), which was explained by a two-step mechanism. During the SiCl4 pulse, a thin layer of Si is deposited, which is carburized by carbon species produced during the C2H4 pulse. Additionally, the separation of precursor pulses should lead to a large increase in the surface coverage of Cl species, further enhancing the inhibition effect and resulting in a superconformal SiC growth. By using this approach, superconformal SiC coatings were achieved at temperatures where conventional CVD only yielded nonconformal SiC coatings. The observed decline in coating conformality with an elongated purge implied that more surface Cl species were replaced by H during the H2 purge and consequently the inhibition effect was diminished. 
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26.
  • Högberg, Cecilia, et al. (författare)
  • Diagnosing colorectal cancer in primary care : cohort study in Sweden of qualitative faecal immunochemical tests, haemoglobin levels, and platelet counts
  • 2020
  • Ingår i: British Journal of General Practice. - London : Royal College of General Practitioners. - 0960-1643 .- 1478-5242. ; 70:701, s. E843-E851
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Colorectal cancer (CRC) diagnostics are challenging in primary care and reliable diagnostic aids are desired. Qualitative faecal immunochemical tests (FITs) have been used for suspected CRC in Sweden since the mid-2000s, but evidence regarding their effectiveness is scarce. Anaemia and thrombocytosis are both associated with CRC. Aim To evaluate the usefulness of qualitative FITs requested for symptomatic patients in primary care, atone and combined with findings of anaemia and thrombocytosis, in the diagnosis of CRC. Design and setting A population-based cohort study using electronic health records and data from the Swedish Cancer Register, covering five Swedish regions. Method Patients aged >= 18 years in the five regions who had provided FITs requested by primary care practitioners from 1 January 2015 to 31 December 2015 were identified. FIT and blood-count data were registered and all CRC diagnoses made within 2 years were retrieved. Diagnostic measurements were calculated. Results In total, 15 789 patients provided FITs (four different brands); of these patients, 304 were later diagnosed with CRC. Haemoglobin levels were available for 13 863 patients, and platelet counts for 10 973 patients. Calculated for the different FIT brands only, the sensitivities for CRC were 81.6%-100%; specificities 65.7%-79.5%: positive predictive values 4.7%-8.1%; and negative predictive values 99.5%-100%. Calculated for the finding of either a positive FIT or anaemia, the sensitivities increased to 88.9-100%. Adding thrombocytosis did not further increase the diagnostic performance. Conclusion Qualitative FITs requested in primary care seem to be useful as rule in tests for referral when CRC is suspected. A negative FIT and no anaemia indicate a low risk of CRC.
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27.
  • Högberg, Cecilia, et al. (författare)
  • Qualitative faecal immunochemical tests (FITs) for diagnosing colorectal cancer in patients with histories of rectal bleeding in primary care : a cohort study
  • 2020
  • Ingår i: International Journal of Colorectal Disease. - : Springer. - 0179-1958 .- 1432-1262. ; 35, s. 2035-2040
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Rectal bleeding is considered an alarm symptom for colorectal cancer (CRC) but it is common and mostly caused by benign conditions. Qualitative faecal immunochemical tests (FITs) for occult blood have been used as diagnostic aids for many years in Sweden when CRC is suspected. The study aimed to evaluate the usefulness of FITs requested by primary care physicians for patients with and without histories of rectal bleeding, in the diagnosis of CRC. Methods Results of all FITs requested in primary care for symptomatic patients in the orebro region during 2015 were retrieved. Data on each patient's history of rectal bleeding was gathered from electronic health records. Patients diagnosed with CRC within 2 years were identified from the Swedish Cancer Register. The analysis focused on three-sample FITs, the customary FIT in Sweden. Results A total of 4232 patients provided three-sample FITs. Information about the presence/absence of rectal bleeding was available for 2027 patients, of which 59 were diagnosed with CRC. For 606 patients with the presence of rectal bleeding, the FIT showed sensitivity 96.2%, specificity 60.2%, positive predictive value 9.8% (95% CI 6.1-13.4) and negative predictive value 99.7% (95% CI 99.2-100) for CRC. For 1421 patients without rectal bleeding, the corresponding figures were 100%, 73.6%, 8.3% (95% CI 5.6-10.9) and 100% (95% CI 99.6-100). Conclusion The diagnostic performance of a qualitative three-sample FIT provided by symptomatic patients in primary care was similar for those with and without a history of rectal bleeding. FITs seem useful for prioritising patients also with rectal bleeding for further investigation.
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28.
  • Högberg, Cecilia, et al. (författare)
  • Use of faecal immunochemical tests common in patients with suspected colorectal cancer but unrelated to travel distance to secondary care : a population-based study from Swedish primary care
  • 2022
  • Ingår i: Scandinavian Journal of Primary Health Care. - : Taylor & Francis Group. - 0281-3432 .- 1502-7724. ; 40:4, s. 459-465
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Evidence is increasing for the use of faecal immunochemical tests (FITs) for occult blood as diagnostic tools when colorectal cancer can be suspected. FITs have been used for this purpose in Swedish primary care since around 2005 despite absence of supporting guidelines. To our knowledge, the extent of this use has not been studied. Objective To investigate the use of FITs as diagnostic tools, and if the use was related to patient age, sex and travel time from primary care to diagnostic facilities in secondary care. Design Population-based retrospective study using data from electronic health records. Setting and subjects Patients >= 18 years that provided FITs in primary care in five Swedish health care regions during 2015. Driving times from their primary care centres to secondary care were calculated. Main outcome measures The proportion of patients that provided FITs was calculated for each region, different age intervals and grouped driving times. Results 18,913 patients provided FITs. The proportion of listed patients in the five regions that provided FITs increased with age: 0.86-1.2% for ages <65 years, 3.6-4.1% for ages 65-79 years and 3.8-6.1% for ages >= 80 years. Differences between the regions were small. There was no overall correlation between the proportion of patients that provided FITs and driving time to secondary care. Conclusion FITs were used extensively in Swedish primary care with a higher use in older age groups. There was no tendency towards a higher use of FITs at primary care centres with longer driving times to secondary care.
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29.
  • Jansson, Eva, et al. (författare)
  • Sitt mindre – all rörelse räknas : [Recommendations on physical activity and sedentary behaviour]
  • 2022
  • Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 119
  • Tidskriftsartikel (refereegranskat)abstract
    • Recommendations on physical activity and sedentary behaviour for improved health have been prepared by Professional Associations for Physical Activity (YFA) and approved by the Swedish Society of Medicine. All adults should do aerobic physical activity 150-300 minutes at moderate or 75-150 minutes at high intensity, or combined, at a weekly basis. For additional health benefits, muscle-strengthening activity should be performed on at least 2 days a week, and sedentary time should be limited and replaced by physical activity. Older adults should, as part of their weekly physical activity, do multicomponent physical activity that emphasizes balance and strength on at least 2-3 days a week to enhance functional capacity and prevent falls. The benefits of physical activity outweigh the risks. The Swedish National Board of Health and Welfare recommends that healthcare providers offer counselling with exercise on prescription to individuals with physical activity under the recommended dose.
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30.
  • Jansson, Johan, et al. (författare)
  • Marknadsföring och varumärken i kollektivtrafiken : Rapport från en kvalitativ studie
  • 2020. - 9
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Kollektivtrafiken är en viktig del i omställningen till ett mer miljömässigt hållbart resande. De alltmer marknads- och kundorienterade regionala kollektivtrafikmyndigheterna marknadsför sig idag med en mängd budskap i en växande flora av kanaler som direktutskick, hemsidor och appar. Denna kommunikation och marknadsföring är en del av den påverkan som resenären har att förhålla sig till i ett allt högre mediebrus. Forskning och lärdomar från privata företag visar att en genomtänkt marknadsföringsstrategi och tydliga varumärkesvärderingar kan bidra till att lyfta attraktivitet och försäljning. Hur ser detta ut inom kollektivtrafikbranschen generellt och hur arbetar de regionala kollektivtrafikmyndigheterna med dessa frågor? Denna rapport presenterar och diskuterar resultatet från en studie kring hur de regionala kollektivtrafikmyndigheterna i Sverige ser på och arbetar med marknadsföring, marknadsorientering och varumärken. Förutom en del rapporter och litteratur i ämnet, baseras rapporten på ett tiotal intervjuer med personer med ansvar för kommunikation, marknadsföring och varumärken i de tre storstadsregionerna Stockholm, Malmö och Göteborg. Resultaten visar att de tre myndigheterna kommit olika långt i sitt arbete med marknadsorientering, marknadsföring och varumärken, och att det ofta saknas en samsyn inom respektive myndighet dels om hur viktigt marknadsförings- och kommunikationsarbetet är, men också om vad som ingår, eller bör ingå i detta arbete. Det är tydligt att aktörerna är i ett uppstartsskede av att tänka och agera i termer av marknadsföringsstrategier och varumärkeshantering och det gör att deras insatser kan upplevas som spretiga och att deras position på marknaden inte är tydlig för viktiga externa intressenter såsom resenärer och företag. Samtidigt är alla tre myndigheterna väl medvetna om vikten av kommunikation som en del i att ta andelar från individuellt bilresande. En stor del av den kommunikation som diskuteras bland myndigheterna rör funktionella aspekter som tidtabellförändringar, störningar och betalningslösningar och denna information samordnas sällan med det generella marknadsförings- och varumärkesarbetet. Kollektivtrafikmyndigheterna har också svårt att tydligt definiera de grundläggande värden som styr deras organisationer och det uppstår därför en skillnad mellan intern och extern syn på deras varumärken som i sin tur leder till ambivalens och en otydlig position på marknaden. Slutsatserna och rekommendationerna kretsar kring att om kollektivtrafikmyndigheterna önskar uppnå ökad kännedom, synlighet, nöjda resenärer och ett ökat anseende både bland resenärer och andra samhällsaktörer bör de arbeta mer strategiskt och långsiktigt med sin kommunikation, utgå från några tydligt förankrade gemensamma värdeord som kan föra dem framåt, och använda dessa för att bygga en tydlig position på marknaden. På sikt skulle detta också öka deras möjligheter att möta andra utmaningar som teknikomställning, förändrade resmönster, ökade krav på tillförlitlighet, säkerhet och prisvärdhet.
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31.
  • Jansson, Ulf, 1966-, et al. (författare)
  • Svenska forskares syn på hantering av rumsliga data - enkätundersökning 2021
  • 2022
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • A survey, aimed at Swedish researchers in the field of spatial data, was conducted in 2021. 113 individuals responded to the questionnaire, which gives us insight into how researchers in the field view; sharing of data, how they work with data, which metadata they think are central and what support they ask for in order to be able to handle spatial data.According to the survey a majority of the researchers share and use data shared by others in their research. Central metadata that is emphasized are coordinate systems, projections, time of the information, data capture, data content and author. The question of how to make data available is very varied among the respondents. The questionnaire responses contain a wide range of individual solutions to make the information available. A majority of researchers believe that the work with data management and accessibility has increased over the past 5 years. As an obstacle to working more with this is time, but there are also other obstacles. The researchers are seeking additional support that can be summarized as: support, technical guidance, storage, information, time and money.
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32.
  • Karlsson, Dennis, 1991- (författare)
  • Additive Manufacturing of Ferritic Materials : A Journey from Stainless Steels to High-Entropy Alloys
  • 2021
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Design of new materials with complex geometries is an important part of new innovative solutions for technical applications. With the use of additive manufacturing (AM), the design possibilities are endless and geometries that are impossible to manufacture by conventional techniques are available. However, the number of alloys commercially available is limited and extensive research is needed to establish new materials with unique properties. An important group of materials is ferritic stainless steels which have a body centered cubic crystal structure. They are often used for their high strength, corrosion resistance or electrical properties at high temperatures. However, they are often less ductile than austenitic stainless steels and issues with cracking may arise during thermal cycling in the L-PBF process. In this thesis, two AM techniques, laser powder bed fusion (L-PBF) and binder jetting were used to produce components of two different ferritic stainless steels and of the AlCoCrFeNi high-entropy alloy (HEA). The main objective was to investigate the microstructural development, phase stabilities and mechanical properties in relation to conventional manufacturing routes. Furthermore, thermodynamic calculations were used to explain the phase stabilities and solidification. L-PBF enables manufacturing of the ferritic stainless steels SS441 and SS446 with excellent mechanical properties. It was shown that solid particles may form in the melt and act as heterogeneous nucleation points, resulting in effective grain refinement for SS441. Other secondary phases can form during the thermal cycling in the L-PBF process, enhancing the mechanical properties. An example is the formation of austenite in SS446. Furthermore, the formation of solid particles and segregated microstructure during solidification was predicted by thermodynamic calculations.The AlCoCrFeNi alloy could be produced with an intriguing hierarchical microstructure and excellent mechanical properties using binder jetting and post-treatments. The microstructure of the final component can also be controlled by pre-annealing of the feedstock powder. Thermodynamic calculations were used to design the phase composition of the alloy. A characteristic single-phase solid solution is only observed at very high temperatures close to the melting point. Hence, the AlCoCrFeNi alloy is not a thermodynamically true HEA, but is stabilized due to kinetic effects during manufacturing.
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33.
  • Karlsson, Dennis, et al. (författare)
  • Additive manufacturing of the ferritic stainless steel SS441
  • 2020
  • Ingår i: Additive Manufacturing. - AMSTERDAM, NETHERLANDS : Elsevier BV. - 2214-8604 .- 2214-7810. ; 36
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, the ferritic stainless steel SS441 was produced with excellent mechanical properties using laser powder bed fusion (L-PBF) compared to samples produced by conventional casting and hot-rolling. In addition, thermodynamic calculations were utilized to study the phase stability at elevated temperatures and to understand the solidification behavior. The hot-rolled sample showed a grain size up to several hundred mu m with additional precipitates of TiN and Nb(C,N). In contrast, the as-built L-PBF samples displayed a grain size in the mu m range. Spherical precipitates with a size of around 50 nm could be observed and were attributed to a corundum phase from the thermodynamic calculations. The printed material shows superior mechanical properties, with more than 30 times higher impact energy compared to the hot-rolled alloy (217 +/- 5 J vs. 7 +/- 0.5 J). Furthermore, the properties are anisotropic for the L-PBF produced alloy, with the highest tensile strength vertical to the build direction. The superior mechanical properties of the L-PBF produced sample can be attributed to a smaller grain size, giving a higher strength according to the Hall-Petch relationship. The anisotropy of the material can be eliminated by heat treatments at 900 degrees C followed by water quenching, but the absolute strength decreases slightly due to formation of intermetallic phases such as Nb(C,N) and the Fe2Nb Laves phase. The results clearly illustrates that L-PBF provides a promising manufacturing mute for enhanced strength of ferritic stainless steels.
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34.
  • Karlsson, Dennis, et al. (författare)
  • Structure and phase transformations in gas atomized AlCoCrFeNi high entropy alloy powders
  • 2022
  • Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 893
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, the crystal structure and phase stability of gas atomized equiatomic AlCoCrFeNi powder was investigated. This alloy is usually described as a high entropy alloy forming a solid solution phase stabilized by a high mixing entropy. However, thermodynamic calculations show that the high entropy phase is stable only at very high temperatures close to the melting point and that a mixture of several phases are the most stable state at lower temperatures. This suggest that kinetic effects may influence the phase composition of atomized powder. The unique features of X-ray diffraction, neutron diffraction as well as transmission electron microscopy were used to study the atomic structure of the atomized powder in detail. The results show that the powder crystallises in an ordered B2 (CsCl-type) structure with a preferred site occupation of Al and Fe on the (1/2 1/2 1/2) position and Co and Ni on the (0 0 0) position. During heat-treatment of the powder, the B2 phase decomposes into fcc and sigma phases and the final phase composition is highly dependent on the heating rate. The effect of heat-treatment on the atomized powder was also investigated and revealed a significant phase transformation with e.g. the formation of sigma phase preferably at the surface of the powder particles. The phase content was also dependent on the size fraction of the powder particles. Sintering of green bodies made with different heat cycles showed that the phase composition of the starting material had a significant impact on the final phase composition and microstructure of the sintered components. The results illustrate the importance of well-defined powder materials for powder consolidation, especially additive manufacturing (binder jetting) of high entropy alloys.
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35.
  • Lundgren, Tobias, et al. (författare)
  • Acceptance and Commitment Training for Ice Hockey Players : A Randomized Controlled Trial
  • 2021
  • Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 12
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent systematic reviews on the topic of mindfulness- and acceptance-based approaches in sport psychology conclude that there is a need for further trials using a more robust research methodology with direct performance as outcome. Acceptance and Commitment Training (ACT) is a contextual behavioral change method that focuses on facilitating psychological processes such as values, committed action, acceptance and mindfulness. In the present study designed as a randomized controlled trial, 34 junior elite ice hockey players were allocated into either an ACT group intervention or a wait list control group. Results showed significant effects on both objective performance outcomes (goals, assists, and taken shots) and blinded coach ratings of players' performance, focus and commitment to their development in favor of the ACT group. Effects lasted at 3-month follow-up for the coach ratings, but not for the objective performance measures. All ACT trained players recommended ACT to other players and considered the training as important for their development as ice hockey players. The results add to the growing body of evidence on ACT interventions for athletes and its effect on performance. Future studies should investigate the maintenance of effects from the psychological training over time, using robust research methodology and investigate theoretical coherent potential mediating variables.
  •  
36.
  • Malinovskis, Paulius, et al. (författare)
  • Synthesis and Characterisation of Nanocomposite Mo-Fe-B Thin Films Deposited by Magnetron Sputtering
  • 2021
  • Ingår i: Materials. - : MDPI. - 1996-1944. ; 14:7
  • Tidskriftsartikel (refereegranskat)abstract
    • Several ternary phases are known in the Mo-Fe-B system. Previous ab initio calculations have predicted that they should exhibit a tempting mix of mechanical and magnetic properties. In this study, we have deposited Mo-Fe-B films with a Fe-content varying from 0-37 at.% using non-reactive DC (direct current) magnetron sputtering. The phase composition, microstructure, and mechanical properties were investigated using X-ray diffraction, scanning transmission electron microscopy, and nanoindentation measurements. Films deposited at 300 degrees C and with >7 at.% Fe are nanocomposites consisting of two amorphous phases: a metal-rich phase and a metal-deficient phase. Hardness and elastic modulus were reduced with increasing Fe-content from similar to 29 to similar to 19 GPa and similar to 526 to similar to 353 GPa, respectively. These values result in H-3/E-2 ratios of 0.089-0.052 GPa, thereby indicating brittle behaviour of the films. Also, no indication of crystalline ternary phases was observed at temperatures up to 600 degrees C, suggesting that higher temperatures are required for such films to form.
  •  
37.
  • Marattukalam, Jithin J., et al. (författare)
  • Development of process parameters for selective laser melting of a Zr-based bulk metallic glass
  • 2020
  • Ingår i: Additive Manufacturing. - : Elsevier. - 2214-8604 .- 2214-7810. ; 33
  • Tidskriftsartikel (refereegranskat)abstract
    • Parameters for selective laser melting of Zr59.3Cu28.8Al10.4Nb1.5 (trade name AMZ4), allowing crack-free bulk metallic glass with low porosity, have been developed. The phase formation was found to be strongly influenced by the heating power of the laser. X-ray amorphous samples were obtained with laser power at and below 75 W. The as-processed bulk metallic glass was found to devitrify by a two-stage crystallization process within which the presence of oxygen was concluded to play an essential role. At laser powers above 75 W, the observed crystallites were found to be a cubic phase (Cu2Zr4O). The hardness and Young’s modulus in the as-processed samples was found to increase marginally with increased fraction of the crystalline phase.
  •  
38.
  • Marattukalam, Jithin James (författare)
  • Tailoring structure and morphology during additive manufacturing of metallic components
  • 2021
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The work described in this thesis explores the use of laser process parameters to functionalize the material properties by the control of microstructure and optimization of morphology in components by selective laser melting. The microstructure in amorphous and crystalline metallic alloy systems is influenced by changing the laser power density and scanning strategies respectively. A combination of X-ray/neutron diffraction and optical/electron microscopy is used to evaluate the microstructure and phase formation in SLM components. The influence of the microstructure on the mechanical properties of as-printed samples was investigated using hardness and uniaxial tensile testing methods. To begin with, the process parameters for selective laser melting of a Zr-based bulk metallic glass Zr59.3Cu28.8Al10.4Nb1.5 (trade name AMLOY-ZR01) are developed to obtain high density and crack-free bulk components. The influence of oxygen on the thermal stability and crystallization pathway in AMLOY-ZR01 was found to be significant in determining the formation of metastable crystalline phases within the amorphous matrix. It was also shown that the mechanical properties in AMLOY-ZR01 can be influenced by changing the amount of crystalline phases formed within the amorphous matrix.  This was achieved by changing the laser power density during the SLM process. The alloy composition was also investigated for its biocompatibility, and the cell-material interactions under in-vitro test conditions showed no cytotoxic effect. These findings demonstrate that AMLOY-ZR01 is a promising candidate for orthopedic bio-implant applications. The latter half of this work demonstrates the influence of microstructure and crystallographic texture on the mechanical properties of 316L SS. This was achieved by changing the "laser scanning methodology" during the SLM process and a correlation between the applied scanning methodology and structure-property relation was identified.  A single crystalline-like texture can be obtained using a bi-directional scanning methodology, whereas a fiber texture is achieved when rotating the laser scan vectors by 67° to melt consecutive powder bed layers. The mechanical properties of 316L SS are influenced by the type of laser scan used to fabricate the components, as it dictates the final grain orientation within the SLM samples. It is also shown that the scanning patterns can be altered during the SLM process to create position-specific crystallographic grain orientation within the component. This opens up the possibility to fabricate functionally graded components which contain a spatial variation in composition and/or microstructure for the specific purpose of controlling material properties. Finally, the functionalization of material properties through design of components by additive manufacturing was demonstrated by fabricating waveguides with the specific geometries.
  •  
39.
  • Marattukalam, Jithin James, et al. (författare)
  • The effect of laser scanning strategies on texture, mechanical properties, and site-specific grain orientation in selective laser melted 316L SS
  • 2020
  • Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 193
  • Tidskriftsartikel (refereegranskat)abstract
    • Selective laser melting has been used to demonstrate the striking effect of laser scanning strategies on the crystalline texture in 316L SS. The aligned crystal orientation along the tensile direction (Z-axis) could be varied using the scanning strategy. A strong 〈100〉 single crystalline-like texture is obtained in the direction of the laser scan and a 〈110〉 texture was observed in the build direction when using a bidirectional scan without rotation. Fiber texture was observed along the tensile direction when the bi-directional laser scanning vectors were rotated by 67° (Rot-scan) for each layer. The study highlights a correlation between laser scanning strategies with resulting textures, microstructure, and mechanical properties in as-printed bulk 316L SS. The hardness, Young's modulus, and ultimate tensile strength were significantly influenced by the final microstructure, crystallographic texture, and porosity. Furthermore, the applied laser scanning strategies made it possible to tailor crystallographic textures locally within the component. This was demonstrated by printing characters with a fiber texture, in a matrix with ⟨100⟩ texture parallel to the Z-axis.
  •  
40.
  • Medina, León Zendejas, et al. (författare)
  • Phase formation in magnetron sputtered CrMnFeCoNi high entropy alloy
  • 2020
  • Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 403
  • Tidskriftsartikel (refereegranskat)abstract
    • Thin films of the CrMnFeCoNi high entropy alloy were deposited by magnetron sputtering from a sintered equimolar target. The substrate temperature and bias were varied during deposition, and the structure, morphology and elemental distribution were studied in detail. All films formed phase mixtures of multiple crystal structures. This contrasts with studies on the bulk alloy, where it typically forms a single phase with a simple cubic closed packed (ccp) structure, with other phases precipitating only after long annealing times. For higher substrate temperatures, we observed a mixture of phases with ccp and bcc (body centered cubic) structures, and the intermetallic phases o-phase and L1(0), the first three being the predicted equilibrium phases at the deposition temperature. For room temperature depositions, we found evidence of very limited diffusion of metal atoms during the deposition. These films formed a mixture of a ccp and the intermetallic chi-phase. Two mechanisms can be distinguished that govern the phase formation at lower and higher temperatures. From the present results and comparisons with the literature, we also discuss why the small grain size, the low process temperature, and the fast surface diffusion during synthesis causes magnetron sputtering to yield different results compared to bulk synthesis from the melt. These principles explain why it is easier to form the equilibrium phases by sputtering, and why a single ccp phase should not be expected as a rule for this deposition method. Following the thermodynamic principles of high entropy alloys, this may also be the case in other high entropy alloy systems.
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41.
  • Mukhamedov, Boburjon, et al. (författare)
  • Tetragonal distortion in magnetron sputtered bcc-W films with supersaturated carbon
  • 2022
  • Ingår i: Materials & design. - : Elsevier Science Ltd. - 0264-1275 .- 1873-4197. ; 214
  • Tidskriftsartikel (refereegranskat)abstract
    • Carbon has a low solid solubility in bcc tungsten at equilibrium. However, metastable supersaturated solid solutions can be synthesized with magnetron sputtering. Here, we present a systematic study on the phase stability and mechanical properties of such supersaturated W-C solid solutions. H-2h scans show a split of the 200/020 and the 002 peaks for supersaturated films which is explained by a tetragonal distortion of the bcc structure. This split increases with increasing C content and is maximized at 4 at.% C, where we observe an a/b axis of 3.15-3.16 A and a c-axis of 3.21-3.22 A. We performed first-principles calculations of lattice parameters, mixing enthalpies, elastic constants and polycrystalline elastic moduli for cubic and tetragonal W-C solid solutions. Calculations show that tetragonal structure is more stable than the bcc supersaturated solid solution and the calculated lattice parameters and Youngs moduli follow the same trends as the experimental ones as a function of C concentration. The results suggest that supersaturated films with lattice distortion can be used as a design approach to improve the properties of transition metal films with a bcc structure. (c) 2022 The Authors. Published by Elsevier Ltd.
  •  
42.
  • Mølmen, Live (författare)
  • Materials Reliability in PEM Fuel Cells
  • 2021
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • As part of the global work towards reducing CO2 emissions, all vehicles needs to be electrified, or fueled by green fuels. Batteries have already revolutionised the car market, but fuel cells are believed to be a key energy conversion system to be able to electrify also heavy duty vehicles. The type of fuel cell commercially available for vehicles today is the polymer electrolyte membrane fuel cell (PEMFC), but for it to be able to take a larger market share, the cost must be reduced while sufficient lifetime is ensured.The PEMFC is a system containing several components, made of different materials including the polymer membrane, noble metal catalyst particles, and metallic bipolar plate. The combination of different materials exposed to elevated temperature, high humidity and low pH make the PEMFC components susceptible to corrosion and degradation.The noble metal catalyst is one of the major contributors to the high cost. In this work, the latest research on new catalyst materials for PEMFCs are overviewed. Furthermore, electrodeposition as a simple synthesis route to test different Pt-alloys for the cathode catalyst in the fuel cell is explored by synthesis of PtNi and PtNiMo. The gas diffusion layer of the PEMFC is used as substrate to reduce the number of steps to form the membrane electrode assembly.In addition to cheaper and more durable materials, understanding of how the materials degrade, and how the degradation affects the other components is crucial to ensure a long lifetime. Finding reliable test methods to validate the lifetime of the final system is necessary to make fuel cell a trusted technology for vehicles, with predictable performance.In this work, commercial flow plates are studied, to see the effect of different load cycles and relative humidities on the corrosion of the plate. Defects originating from production is observed, and the effect of these defects on the corrosion is further analysed. Suggestions are given on how the design and production of bipolar plates should be made to reduce the risk of corrosion in the PEMFC.
  •  
43.
  • Osinger, Barbara, 1995- (författare)
  • Investigation of compositionally complex refractory metal based thin films
  • 2024
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The search for new and improved materials has led to the discovery and establishment of compositionally complex or high-entropy materials. The work in this thesis is focused on the investigation of new compositionally complex materials based on the refractory metals of groups 4-6. The materials in this work were synthesised using non-reactive dc magnetron sputtering and three material systems have been studied: HfNbTiVZr-C, CrTiTaWNb-C and Nb-Mo-C. In the context of compositionally complex materials, this thesis aims to contribute specifically to questions regarding (i) the prediction of phase formation and stability (ii) the chemical interaction between atoms (iii) the correlation between the material properties and compositional complexity. The prediction of phase formation and stability using calculated phase diagram (CALPHAD) methods was studied in the HfNbTiVZr-C system. The findings suggest that CALPHAD methods are promising predictive tools, although kinetic effects during synthesis need to be taken into consideration. Furthermore, theoretical, and experimental evidence of charge transfer effects was demonstrated within the HfNbTiVZr-C system. The results of ab initio materials simulations and X-ray Photoelectron Spectroscopy (XPS) measurements highlight the importance of understanding and considering the local chemical environment and chemical interactions in compositionally complex materials.The approach of metal alloying according to the valence electron concentration (VEC) to tune the mechanical properties was studied in the Nb-Mo-C system. The findings show the importance of microstructural effects on the mechanical properties in the studied thin film materials, which can overshadow the compositional or VEC variations. The response to Xe heavy-ion irradiation was studied in the CrTiTaWNb-C system using in situ irradiation experiments. This work presents a comparison between three different compositions: a TaW-rich alloy and carbide thin film as well as a near-equimolar carbide film. The findings indicate that both microstructure and chemical homogeneity play important roles when it comes to radiation damage tolerance in compositional complex materials.This thesis demonstrates the elaborate and multifaceted nature of compositionally complex materials. Whether it comes to the fundamental understanding or the effective implementation of a materials design tool, many factors need to be taken into consideration, including chemical interactions between the constituent elements and microstructural effects.
  •  
44.
  • Osinger, Barbara, et al. (författare)
  • Investigation of the phase formation in magnetron sputtered hard multicomponent (HfNbTiVZr)C coatings
  • 2022
  • Ingår i: Materials & design. - : ELSEVIER SCI LTD. - 0264-1275 .- 1873-4197. ; 221
  • Tidskriftsartikel (refereegranskat)abstract
    • Multicomponent carbides have gained interest especially for ultra-high temperature applications, due to their ceramic hardness, good oxidation resistance and enhanced strength. In this study the phase forma-tion, stability and mechanical properties of (HfNbTiVZr)C multicomponent carbide coatings were inves-tigated. Phase stability was predicted by the CALPHAD (CALculation of PHAse Diagrams) methods. This revealed that the multicomponent solid solution phase is only stable at elevated temperatures, namely above 2400 degrees C. At lower temperatures a phase mixture was predicted, with a particular tendency for V to segregate. Magnetron sputtered thin films deposited at 300 degrees C exhibited a single NaCl-type multicom-ponent carbide phase, which attributes to the kinetic stabilisation of simple structures during thin film growth. Films deposited at 700 degrees C, or exposed to UHV annealing at 1000 degrees C, however, revealed the decom-position of the single-phase multicomponent carbide by partial elemental segregation and formation of additional phases. Thus, confirming the CALPHAD predictions. These results underscore the importance of explicitly considering temperature when discussing the stability of multicomponent carbide materials, as well as the applicability of CALPHAD methods for predicting phase formation and driving forces in these materials. The latter being crucial for designing materials, such as carbides, that are used in appli-cations at elevated temperatures.
  •  
45.
  • Osinger, Barbara, et al. (författare)
  • Structural and mechanical properties of magnetron sputtered (NbxMo1-x)C thin films
  • 2024
  • Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 224
  • Tidskriftsartikel (refereegranskat)abstract
    • While transition metal carbides (TMCs) exhibit favourable mechanical properties, alloying according to the valence electron concentration (VEC) has the potential to further enhance the properties of these hard but inherently brittle materials. This study investigates the influence of alloying on the microstructure and mechanical properties of (NbxMo1-x)C carbide films, including binary references and ternary compositions with varying metal ratios (x between 0.35 and 0.53). Furthermore, the influence of various substrate materials is studied by comparing films deposited on Al2O3, MgO and SiO2. All films exhibit a NaCl-type carbide structure and X-ray photoelectron spectroscopy revealed the presence of small amounts of an additional amorphous carbon (a-C) phase. Hardness values around 20 ± 2 GPa were obtained for the films on Al2O3 and MgO, whereas a reduced hardness of 11 ± 1 GPa was observed for the films on SiO2 which is attributed to larger crystallite size and more polycrystalline structure. Overall no clear trend as a function of composition can be noted, indicating that microstructure effects dominate the mechanical properties in this study overshadowing the effect of varying the metal content.
  •  
46.
  • Pacheco, Victor (författare)
  • Processing–Structure–Properties Relationship in Metal Additive Manufacturing
  • 2021
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The last three decades have seen the transition of additive manufacturing, from applications exclusively in rapid-prototyping to an emerging production method in the manufacturing industry that is rapidly gaining more relevance. Within additive manufacturing methods, selective laser melting (SLM) is one of the most widely used and mature technologies and is the focus of this thesis. In particular, this work aims at characterizing novel microstructures and/or alloys produced with SLM and to understand how the process parameters influence the microstructure and properties.Hitherto, the most prevalent material selection approach for SLM has been the use and optimization of well-known alloys, such as steels, Ni- and Ti-based alloys, among others. Favorable microstructures are usually achieved with a combination of appropriate parameters and post-processing techniques. Another approach, especially interesting from a research perspective, is the exploration of materials and microstructures suited for the inherent characteristics of SLM. In alignment with the latter strategy, three types of materials are successfully produced and analyzed in this work: the amorphous Zr-based AMZ4 alloy, 316L stainless steel with strong preferential orientation (i.e., similar orientation of the crystalline structure of the grains) and the intermetallic MnAl(C) with strong preferential orientation. The latter contains a ferromagnetic phase with potential applications as a permanent magnet.SLM was found to be an effective method to produce the amorphous phase in the Zr59.3Cu28.8Al10.4Nb1.5 system (AMZ4). The laser power and oxygen impurities were found to have a central role in the formation of crystalline particles in the amorphous matrix. These crystalline particles and the oxygen impurities reduced the thermal stability of the alloy in comparison to specimens fabricated by suction casting. For the more conventional 316L stainless steel, it was demonstrated that the scan strategy can be used to influence the type of texture, with a notable effect on the mechanical properties. In the case of MnAl(C), it was established that the high temperature polymorph – ε-phase, can be retained during the printing process. This phase can be subsequently transformed to the ferromagnetic τ-phase with annealing procedures. It was observed that a strong preferred orientation of the ε-phase can be achieved, although it did not translate into a strong texture in the τ-phase (after the heat treatments). The research methodology used in this thesis and the findings regarding the processing–structure–properties relationship in SLM provide an important reference for future studies of novel materials and microstructures produced by additive manufacturing.
  •  
47.
  • Pacheco, Victor, et al. (författare)
  • Thermal stability and crystallization of a Zr-based metallic glass produced by suction casting and selective laser melting
  • 2020
  • Ingår i: Journal of Alloys and Compounds. - : ELSEVIER SCIENCE SA. - 0925-8388 .- 1873-4669. ; 825
  • Tidskriftsartikel (refereegranskat)abstract
    • The thermal stability and crystallization mechanism of the Zr59.3Cu28.8Al10.4Nb1.5 (at%) metallic glass produced through selective laser melting SLM (from industrial grade material) was studied and compared with the same alloy produced by suction casting (from laboratory grade material of high purity). Oxygen- and Al-rich particles of a cubic phase (Fd (3) over barm) with a size of up to 200 nm are detected in the as-built selective laser melted samples by transmission electron microscopy. The crystallization process of the cast and SLM samples is investigated by in-situ X-ray diffraction experiments. In the cast samples, the initial crystallization occurs via the formation of a metastable tetragonal phase (Al2Zr3), together with tetragonal CuZr2 and hexagonal Al3Zr4 type structures, while the SLM samples initially crystallize through the formation of the metastable, oxygen- and Al-rich, cubic phase already present before annealing. The main phases present at the end of the crystallization for both type of samples are the same, mainly CuZr2 and Al3Zr4. The differences in the crystallization paths are attributed to differences in the oxygen levels. In general, the higher oxygen content (similar to 1 at%) of the SLM samples results in a decrease of the thermal stability of the alloy and promotes the formation of an oxygen-rich, metastable cubic phase. 
  •  
48.
  • Paschalidou, Eirini-Maria, et al. (författare)
  • Corrosion studies on multicomponent CoCrFeMnNi(C) thin films in acidic environments
  • 2022
  • Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 404
  • Tidskriftsartikel (refereegranskat)abstract
    • The corrosion resistances of near equimolar CoCrFeMnNi magnetron-sputtered thin films with different carbon concentrations were examined in 0.05 M HCl and 0.05 M H2SO4. Polarization curves were recorded with different scan rates with and without reducing the native oxide. The results showed that the carbon concentration and the experimental conditions affected the electrochemical behaviour mainly in the Cr transpassive region. At potentials above 850 mV, the carbon-containing films were more corrosion resistant in 0.05 M HCl than in 0.05 M H2SO4 due to a lower carbon oxidation rate in 0.05 M HCl, facilitating the formation of a Mn-rich oxide layer. (C)& nbsp;2021 The Author(s). Published by Elsevier Ltd.& nbsp;
  •  
49.
  •  
50.
  • Skripnyak, Natalia, et al. (författare)
  • Achieving low elastic moduli of bcc Ti-V alloys in vicinity of mechanical instability
  • 2020
  • Ingår i: AIP Advances. - : AMER INST PHYSICS. - 2158-3226. ; 10:10
  • Tidskriftsartikel (refereegranskat)abstract
    • Body centered cubic (bcc) Ti-based alloys are of interest for multiple technological applications ranging from aerospace technology to biomedicine. However, these alloys are usually unstable at low temperatures. Indeed, the calculated elastic modulus C of bcc Ti-V alloys with low V concentrations is negative at 0 K temperature, indicating their mechanical instability. Here, we investigate elastic moduli of the Ti-V system in the vicinity of mechanical instability theoretically and experimentally. Our calculations predict that mechanical stabilization of bcc Ti-V alloys, which is governed by the hardening of C , is possible at as low V concentration as 18 at.%. We synthesize single-phase bcc alloys with as little as 22 at.% of V with low values of Youngs modulus. Moreover, we predict strong concentration dependence of anisotropy of Youngs modulus in these alloys that can also be used in tuning the alloy composition to design materials for specific applications.
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