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- Karhu, Elisa, et al.
(författare)
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Exercise and gastrointestinal symptoms : running-induced changes in intestinal permeability and markers of gastrointestinal function in asymptomatic and symptomatic runners
- 2017
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 117:12, s. 2519-2526
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Tidskriftsartikel (refereegranskat)abstract
- Athletes frequently experience gastrointestinal (GI) symptoms during training and competition. Although the prevalence of exercise-induced GI symptoms is high, the mechanisms leading to GI distress during exercise are not fully understood. The aim of this study was to identify running-induced changes in intestinal permeability and markers of GI function and investigate their association with gastrointestinal symptoms. We recruited 17 active runners who we allocated as either asymptomatic or symptomatic based on their history of experiencing GI symptoms during running. The participants took part in a running test where they were asked to run for 90 min at 80% of their best 10 km race speed. Intestinal permeability was measured at baseline and after the running test. Levels of serum intestinal fatty acid-binding protein (I-FABP), zonulin, bacterial lipopolysaccharide (LPS), and fecal calprotectin were also measured at baseline and after the running test. Running induced a significant increase in intestinal permeability and serum I-FABP concentration but there were no differences between asymptomatic and symptomatic runners. Serum LPS activity did not change from baseline following the running test but the symptomatic group exhibited higher LPS activity at baseline compared to the asymptomatic runners. Running for 90 min at a challenging pace causes small intestinal damage and increases intestinal permeability. However, these alterations in GI function do not appear to correlate with the development of GI symptoms during running.
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| 3. |
- Lindberg, Anders, et al.
(författare)
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Mechanical performance of polymer powder bed fused objects - FEM simulation and verification
- 2018
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Ingår i: Additive Manufacturing. - : ELSEVIER SCIENCE BV. - 2214-8604 .- 2214-7810. ; 24, s. 577-586
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing (3D printing) enables the designing and producing of complex geometries in a layer-by layer approach. The layered structure leads to anisotropic behaviour in the material. To accommodate anisotropic behaviour, geometrical optimization is needed so that the 3D printed object meets the pre-set strength and quality requirements. In this article a material description for polymer powder bed fused also or selective laser sintered (SLS) PA12 (Nylon-12), which is a common 3D printing plastic, was investigated, using the Finite Element Method (FEM). The Material Model parameters were obtained by matching them to the test results of multipurpose test specimens (dumb-bells or dog bones) and the model was then used to simulate/predict the mechanical performance of the SLS printed lower-leg prosthesis components, pylon and support. For verification purposes, two FEM designs for a support were SLS printed together with additional test specimens in order to validate the used Material Model. The SLS printed prosthesis pieces were tested according to ISO 10328 Standard. The FEM simulations, together with the Material Model, was found to give good estimations for the location of a failure and its load. It was also noted that there were significant variations among individual SLS printed test specimens, which impacted on the material parameters and the FEM simulations. Hence, to enable reliable FEM simulations for the designing of 3D printed products, better control of the SLS process with regards to porosity, pore morphology and pore distribution is needed.
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