| 1. |
- Alijagic, Andi, 1992-, et al.
(författare)
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Particle Safety Assessment in Additive Manufacturing : From Exposure Risks to Advanced Toxicology Testing.
- 2022
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Ingår i: Frontiers in Toxicology. - : Frontiers Media S.A.. - 2673-3080. ; 4
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Forskningsöversikt (refereegranskat)abstract
- Additive manufacturing (AM) or industrial three-dimensional (3D) printing drives a new spectrum of design and production possibilities; pushing the boundaries both in the application by production of sophisticated products as well as the development of next-generation materials. AM technologies apply a diversity of feedstocks, including plastic, metallic, and ceramic particle powders with distinct size, shape, and surface chemistry. In addition, powders are often reused, which may change the particles' physicochemical properties and by that alter their toxic potential. The AM production technology commonly relies on a laser or electron beam to selectively melt or sinter particle powders. Large energy input on feedstock powders generates several byproducts, including varying amounts of virgin microparticles, nanoparticles, spatter, and volatile chemicals that are emitted in the working environment; throughout the production and processing phases. The micro and nanoscale size may enable particles to interact with and to cross biological barriers, which could, in turn, give rise to unexpected adverse outcomes, including inflammation, oxidative stress, activation of signaling pathways, genotoxicity, and carcinogenicity. Another important aspect of AM-associated risks is emission/leakage of mono- and oligomers due to polymer breakdown and high temperature transformation of chemicals from polymeric particles, both during production, use, and in vivo, including in target cells. These chemicals are potential inducers of direct toxicity, genotoxicity, and endocrine disruption. Nevertheless, understanding whether AM particle powders and their byproducts may exert adverse effects in humans is largely lacking and urges comprehensive safety assessment across the entire AM lifecycle-spanning from virgin and reused to airborne particles. Therefore, this review will detail: 1) brief overview of the AM feedstock powders, impact of reuse on particle physicochemical properties, main exposure pathways and protective measures in AM industry, 2) role of particle biological identity and key toxicological endpoints in the particle safety assessment, and 3) next-generation toxicology approaches in nanosafety for safety assessment in AM. Altogether, the proposed testing approach will enable a deeper understanding of existing and emerging particle and chemical safety challenges and provide a strategy for the development of cutting-edge methodologies for hazard identification and risk assessment in the AM industry.
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| 2. |
- Gåård, Anders, 1977-, et al.
(författare)
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Nano-scale friction of multi-phase powder metallurgy tool steels
- 2015
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Ingår i: Advanced Materials Research. - : Trans Tech Publications. - 1022-6680 .- 1662-8985. ; 1119, s. 70-74
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Tidskriftsartikel (refereegranskat)abstract
- Friction is a fundamental phenomenon in tribology involving complex mechanisms between thecontacting surfaces. Measurements of friction are often made using devices with substantially largercontact area than dimensions corresponding to microstructural features of the materials. Hence, for multi-phase materials,influence of particular microstructural constituents is not resolved. In the present work, a tribometerwith a contact area in the nano-scale range was used to map friction for different types of tool steelswith different chemical- and phase composition. Owing to the small tip radius, frictionalcharacteristics of primary carbides and the steel matrix were measured and compared. Dependingon chemical composition, a difference was observed where the coefficient of friction wasapproximately twice higher for the steel possessing highest coefficient of friction, including bothcarbides and the steel matrix.
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| 3. |
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| 4. |
- Karlsson, Patrik, 1973-, et al.
(författare)
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Galling resistance and wear mechanisms for cold-work tool steels in lubricated sliding against high strength stainless steel sheets
- 2012
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Ingår i: Wear. - Amsterdam : Elsevier. - 0043-1648 .- 1873-2577. ; 286-287, s. 92-97
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Tidskriftsartikel (refereegranskat)abstract
- Tool damage in sheet metal forming of stainless steel is of high concern for the forming industry. In the present work, ingot cast AISI D2 and advanced powder metallurgy tool steel (PM) cold-work tool steels were evaluated and ranked regarding wear mechanisms and galling resistance. Wear tests were performed using a slider-on-flat-surface (SOFS) tribometer in sliding against austenitic–ferritic (duplex) stainless steel sheets at different contact pressures in lubricated conditions. The best galling resistance was observed for the nitrogen alloyed PM tool steels. Abrasive scratching of the tool surfaces and transfer of sheet material due to adhesive wear were the main metal forming tool surface damage mechanisms. By increasing the hardness of one PM sheet metal forming tool grade, the galling resistance was enhanced.
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| 5. |
- Karlsson, Patrik, 1973-, et al.
(författare)
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Influence of size and distribution of hard phases in tool steels on the early stage of galling
- 2012
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Ingår i: TOOL 2012. - Knittelfeld : Verlag "Gutenberghaus". - 9783901384523
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Konferensbidrag (refereegranskat)abstract
- In sheet metal forming processes, contact pressures are relatively high and total sliding distances are long, which demands tool steels to prevent tool damage and to resist galling. Galling is related to microscopic and macroscopic material transfer, but, the mechanisms of initiation are not thoroughly understood.To investigate galling initiation, lubricated sliding testing in the Slider-On-Flat-Surface (SOFS) tribometer was performed for ingot cast (IC) AISI D2 type and nitrogen alloyed powder metallurgy (PM) tool steel. The sheet grade was EN 1.4509 ferritic stainless steel. To reveal mechanisms in the early stages of galling initiation, transfer and accumulation of sheet material to the tool surfaces were characterized using AFM and SEM.It was found that already after a short sliding distance, transfer of sheet material occurred covering both the matrix and the hard phases. Macroscopic analysis of the contact area showed that initial material transfer and further lump growth occurred at positions corresponding to high plastic strains in the sheet material. Even though initial material transfer was observed for both tested tool steels, the sliding distance to the point where transfer and further lump formation occurred was longer for the PM tool steel. This was discussed in correlation to differences in size and distribution of the hard phases in the tool steels, which was confirmed by AFM and SEM.
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| 6. |
- Karlsson, Patrik, 1973-, et al.
(författare)
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Influence of work material proof stress and tool steel microstructure on galling initiation and critical contact pressure
- 2013
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Ingår i: Tribology International. - Amsterdam : Elsevier. - 0301-679X .- 1879-2464. ; 60, s. 104-110
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Tidskriftsartikel (refereegranskat)abstract
- EN 1.4301 (austenitic), EN 1.4509 (ferritic), EN 1.4162 (duplex) and EN 1.4310 C1000 (metastable austenitic) stainless steels were tested in lubricated sliding against an ingot cast EN X153WCrMoV12 and powder metallurgy nitrogen alloyed Uddeholm Vancron 40 tool steels to reveal critical to galling contact pressure, Pcr. The calculated Pcr were higher for steels with higher strength. At P>Pcr, due to plastic flow of sheet material, the tool is damaged substantially and wear-induced matrix damage causes rapid galling initiation. At P
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| 7. |
- Alijagic, Andi, 1992-, et al.
(författare)
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A Novel Nanosafety Approach Using Cell Painting, Metabolomics, and Lipidomics Captures the Cellular and Molecular Phenotypes Induced by the Unintentionally Formed Metal-Based (Nano)Particles
- 2023
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Ingår i: Cells. - : MDPI. - 2073-4409. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing (AM) or industrial 3D printing uses cutting-edge technologies and materials to produce a variety of complex products. However, the effects of the unintentionally emitted AM (nano)particles (AMPs) on human cells following inhalation, require further investigations. The physicochemical characterization of the AMPs, extracted from the filter of a Laser Powder Bed Fusion (L-PBF) 3D printer of iron-based materials, disclosed their complexity, in terms of size, shape, and chemistry. Cell Painting, a high-content screening (HCS) assay, was used to detect the subtle morphological changes elicited by the AMPs at the single cell resolution. The profiling of the cell morphological phenotypes, disclosed prominent concentration-dependent effects on the cytoskeleton, mitochondria, and the membranous structures of the cell. Furthermore, lipidomics confirmed that the AMPs induced the extensive membrane remodeling in the lung epithelial and macrophage co-culture cell model. To further elucidate the biological mechanisms of action, the targeted metabolomics unveiled several inflammation-related metabolites regulating the cell response to the AMP exposure. Overall, the AMP exposure led to the internalization, oxidative stress, cytoskeleton disruption, mitochondrial activation, membrane remodeling, and metabolic reprogramming of the lung epithelial cells and macrophages. We propose the approach of integrating Cell Painting with metabolomics and lipidomics, as an advanced nanosafety methodology, increasing the ability to capture the cellular and molecular phenotypes and the relevant biological mechanisms to the (nano)particle exposure.
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| 8. |
- Alijagic, Andi, 1992-, et al.
(författare)
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Immunotoxic, genotoxic, and endocrine disrupting impacts of polyamide microplastic particles and chemicals
- 2024
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 183
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Tidskriftsartikel (refereegranskat)abstract
- Due to their exceptional properties and cost effectiveness, polyamides or nylons have emerged as widely used materials, revolutionizing diverse industries, including industrial 3D printing or additive manufacturing (AM). Powder-based AM technologies employ tonnes of polyamide microplastics to produce complex components every year. However, the lack of comprehensive toxicity assessment of particulate polyamides and polyamide-associated chemicals, especially in the light of the global microplastics crisis, calls for urgent action. This study investigated the physicochemical properties of polyamide-12 microplastics used in AM, and assessed a number of toxicity endpoints focusing on inflammation, immunometabolism, genotoxicity, aryl hydrocarbon receptor (AhR) activation, endocrine disruption, and cell morphology. Specifically, microplastics examination by means of field emission scanning electron microscopy revealed that work flow reuse of material created a fraction of smaller particles with an average size of 1-5 µm, a size range readily available for uptake by human cells. Moreover, chemical analysis by means of gas chromatography high-resolution mass spectrometry detected several polyamide-associated chemicals including starting material, plasticizer, thermal stabilizer/antioxidant, and migrating slip additive. Even if polyamide particles and chemicals did not induce an acute inflammatory response, repeated and prolonged exposure of human primary macrophages disclosed a steady increase in the levels of proinflammatory chemokine Interleukin-8 (IL-8/CXCL-8). Moreover, targeted metabolomics disclosed that polyamide particles modulated the kynurenine pathway and some of its key metabolites. The p53-responsive luciferase reporter gene assay showed that particles per se were able to activate p53, being indicative of a genotoxic stress. Polyamide-associated chemicals triggered moderate activation of AhR and elicited anti-androgenic activity. Finally, a high-throughput and non-targeted morphological profiling by Cell Painting assay outlined major sites of bioactivity of polyamide-associated chemicals and indicated putative mechanisms of toxicity in the cells. These findings reveal that the increasing use of polyamide microplastics may pose a potential health risk for the exposed individuals, and it merits more attention.
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| 9. |
- Gonzales-Siles, Lucia, et al.
(författare)
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A Pangenome Approach for Discerning Species-Unique Gene Markers for Identifications of Streptococcus pneumoniae and Streptococcus pseudopneumoniae
- 2020
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Ingår i: Frontiers in Cellular and Infection Microbiology. - : Frontiers Media SA. - 2235-2988. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Correct identifications of isolates and strains of the Mitis-Group of the genus Streptococcus are particularly difficult, due to high genetic similarity, resulting from horizontal gene transfer and homologous recombination, and unreliable phenotypic and genotypic biomarkers for differentiating the species. Streptococcus pneumoniae and Streptococcus pseudopneumoniae are the most closely related species of the clade. In this study, publicly-available genome sequences for Streptococcus pneumoniae and S. pseudopneumoniae were analyzed, using a pangenomic approach, to find candidates for species-unique gene markers; ten species-unique genes for S. pneumoniae and nine for S. pseudopneumoniae were identified. These species-unique gene marker candidates were verified by PCR assays for identifying S. pneumoniae and S. pseudopneumoniae strains isolated from clinical samples. All determined species-level unique gene markers for S. pneumoniae were detected in all S. pneumoniae clinical isolates, whereas fewer of the unique S. pseudopneumoniae gene markers were present in more than 95% of the clinical isolates. In parallel, taxonomic identifications of the clinical isolates were confirmed, using conventional optochin sensitivity testing, targeted PCR-detection for the "Xisco" gene, as well as genomic ANIb similarity analyses for the genome sequences of selected strains. Using mass spectrometry-proteomics, species-specific peptide matches were observed for four of the S. pneumoniae gene markers and for three of the S. pseudopneumoniae gene markers. Application of multiple species-level unique biomarkers of S. pneumoniae and S. pseudopneumoniae, is proposed as a protocol for the routine clinical laboratory for improved, reliable differentiation, and identification of these pathogenic and commensal species.
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| 10. |
- Karlsson Häikiö, Tarja, et al.
(författare)
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Experiences from creating opportunities for producing senior lecturers in Sloyd and Visual Art Education
- 2024
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Ingår i: NERA 2024. - Malmö.
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Konferensbidrag (refereegranskat)abstract
- The Swedish Research Council (Vetenskapsrådet, VR), has funded the National Graduate School in Visual Arts and Sloyd Education, FoBoS) (Sw. Nationella forskarskolan i bildpedagogik och slöjdpedagogik). This graduate school is a collaboration between Gothenburg University, Stockholm University and Konstfack University of Arts, Crafts and Design. The work with the Graduate school began in 2019 and the first PhD students for Degree of Licentiate started in January 2020. FoBoS have contributed to practice-based research and quality in higher education in the subjects Visual Art and Sloyd Education and in this way contributed to establishing the subjects on postgraduate level by producing new researchers.There is an urgent need to do more research in Sloyd and Visual Arts Education in Sweden. The current situation in these minor school subjects is limited. Lack of research programs as well as doctoral positions means that these studies seldom can build an autonomous research environment with advisors which can support the subject’s specific inquiries, theories and methods. There is also a lack of educators in Swedish universities in subject didactics in general (The Research Council, 2023).FoBoS has been part of the strategic investment in graduate schools that has been important for “the supply of skills and to further strengthen the field of educational science as well as the scientific basis of teacher education and the school” (The Research Council, 2023 p. 6). Secure resources for career paths for new researchers and building excellent research environments as a result of the national research schools, subject didactic research, research on learning processes, on professions and professional training. Collaborative doctoral students are important as there is still a "weak connection between research on teaching and the teachers' everyday school life, as well as insufficient conditions to use knowledge from research and proven experience in the activities" (The Research Council, 2023 p. 14).In this Roundtable discussion we in the steering group of FoBoS share our experiences of our work with the graduate school, in particular challenges in supporting the development of research in this area. Some of these challenges relate to structural conditions and how support for research and graduate schools is organized. Other challenges are how to create possibilities for continued trajectories from licentiate studies to doctoral studies, as well as onwards towards post-doctoral positions. What does the future look like for postgraduate education in the subjects and in higher education? What are the conditions for producing more researchers, career opportunities and postdocs? Despite an increased number of PhD:s in educational science, there is a great shortage of researchers for teacher training, even in the aesthetic subjects "to meet the societal challenges that characterize schools and higher education today" (The Research Council, 2023 p. 6). We in the steering group for FoBoS are interested in discussing how to create new opportunities for more research and researchers in Sloyd and Visual Arts. We invite you in our Roundtable discussion.ReferencesThe Research Council [Vetenskapsrådet] (2023). Forskningsöversikt 2023. Utbildningsvetenskap. Stockholm.
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