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- Alijagic, Andi, 1992-, et al.
(author)
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Particle Safety Assessment in Additive Manufacturing : From Exposure Risks to Advanced Toxicology Testing.
- 2022
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In: Frontiers in Toxicology. - : Frontiers Media S.A.. - 2673-3080. ; 4
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Research review (peer-reviewed)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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- Börjesson Axén, Jenny, 1986-, et al.
(author)
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A Structural Investigation into the OCV Hysteresis of the Ni(OH)2 Electrode
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Other publication (other academic/artistic)abstract
- Powder X-ray diffraction (XRPD), X-ray absorption spectroscopy (EXAFS and XANES) and Raman spectroscopy were used to study chemical changes in the polycrystalline nickel hydroxide positive electrode material of a NiMH battery at four states of charge: 0%, 50% and 100% charged, and 50% discharged. The two 50% samples were at the same state of charge but in different hysteresis states, manifested by differences in the open circuit potential. The nickel hydroxide electrodes consist of particles in the µm size range, and all measurements were performed ex situ. The material studied was taken from commercial batteries and as such contained both metallic nickel particles, cobalt, and zinc dopants in the active Ni(OH)2 material as well as a cobalt oxide surface layer. Combining the results from all the characterization methods was necessary to better understand the chemistry behind the physio-chemical hysteresis behavior in this complex system. Our results show that there are structural differences between the two 50% samples. Comparison of the XRPD results and the EXAFS results on the nickel edge indicate a presence of the kinetically favored TP2-NiOOH phase in the transition between β-Ni(OH)2 and β-NiOOH and that the amount differs between the two hysteresis states. The measurements on the zinc edge using EXAFS and XANES suggest short range differences in the active material bulk that stems from disorder. Raman spectroscopy measurements show a difference in degree of lithium intercalation in the LiCoO2 surface layer between the hysteresis states. As electrochemistry takes place on the surface of the particles, it is likely that differences in the surface structure are responsible for the open circuit voltage hysteresis. However, due to the coherence of the structure differences detected, it is probable that they are all connected and have a part in the observed behavior.
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- Eriksson, Helen, et al.
(author)
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Techniques for and consequences of using INSPIRE extensions : a case study with Swedish hydrological data
- 2018
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In: International Journal of Spatial Data Infrastructures Research. - : Publication Office of the European Union. - 1725-0463. ; 13, s. 172-201
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Journal article (peer-reviewed)abstract
- The demand for easily available geographic information is increasing in society. Moreover, knowledge of spatial data infrastructures (SDIs) has increased in many European governmental agencies, in large part because of the implementation of the INSPIRE directive. Many countries, thus, recognise the need to provide more detailed geographic information as network services at the national level. One means of realising this goal is to create INSPIRE extensions, i.e., to extend the INSPIRE data specifications with more detailed and specific national information. This paper describes a study where a complex INSPIRE extension has been created to describe the national need of hydrography information in Sweden, based on the Swedish water system standard (SWSS). The study includes the creation of a UML application schema that extends the INSPIRE Hydrography (HY) theme, the transform from UML to an XSD schema, the creation of GML files, and finally, testing and evaluating the approach of using INSPIRE extensions. When evaluating the results, the consequences of replacing existing dataset/download services with one extended INSPIRE HY dataset/download service are evaluated from the perspectives of both users and data providers. The evaluation is carried out as quantitative tests of the resulting GML files, in a user-centric test where a user tests the applicability of the GML files in hydrological analyses, and by telephone interviews with personnel from Lantmäteriet, the Swedish mapping, cadastral and land registration authority. Beside these evaluations, the possible effects on the information modelling process when creating an INSPIRE extension are also examined. The study shows that it is possible to create complex INSPIRE extensions that include many object types, attributes and relations. From a user perspective, extended INSPIRE HY files do not differ substantially from SWSS files, and can be used in hydrological analyses. Data providers can relatively simply replace their current download services with one for the extended INSPIRE HY, but the specific economic consequences for this could not be drawn. It could be expected, though, that there can be both economic, administrative and maintenance advantages if today’s separate INSPIRE and national download services are replaced with services exposing datasets based on an extended INSPIRE data model for all adequate themes.
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- Sjöström, Anders, et al.
(author)
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Vibration insulation of footbridges so as to reduce human discomfort
- 2014
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In: INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control. - 9780909882037
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Conference paper (peer-reviewed)abstract
- Low frequency vibrations in footbridges is a cause of annoyance for pedestrians crossing the bridge. Bagers bro, a footbridge built in Malmö (Sweden) had several constraints in the physical design that caused the first eigenmode of the bridge to be at 1.8Hz which is a severe problem for pedestrians. Therefore the bridge was fitted with tuned mass dampers to mitigate the vibration problem. To evaluate the performance of the dampers and the accuracy in the predictions of the Finite Element (FE) Models of the bridge, an investigation trough modeling and measurements with respect to the performance of the tuned dampers fitted to the bridge has been done. The measurements were performed both with and without the mass dampers engaged. The results from the operational modal analysis of the bridge were compared with finite element simulations. The mass dampers were found to greatly improve the vibratory performance of the bridge in as much as making an otherwise almost unusable bridge acceptable.
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- Sjöström, Anders, et al.
(author)
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Wind turbine tower resonance
- 2014
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In: INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control. - 9780909882037
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Conference paper (peer-reviewed)abstract
- Wind turbine towers are large structures designed to withstand the unique loading conditions imposed on them by the turbine's nacelle and dynamic forces from the rotating blades. Observations and noise measurements of a particular wind turbine showed high noise levels at approximately 48 Hz, which could not be explained from the usual known potential noise sources. Correlated far field noise measurements and vibration measurements collected on the turbine tower, structural base and nearby ground have shown the source to be a resonance of the tower structure.
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