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| 2. |
- Jensen, Vivi F.H., et al.
(författare)
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Inner histopathologic changes and disproportionate zone volumes in foetal growth plates following gestational hypoglycaemia in rats
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Maternal hypoglycaemia throughout gestation until gestation day (GD)20 delays foetal growth and skeletal development. While partially prevented by return to normoglycaemia after completed organogenesis (GD17), underlying mechanisms are not fully understood. Here, we investigated the pathogenesis of these changes and significance of maternal hypoglycaemia extending beyond organogenesis in non-diabetic rats. Pregnant rats received insulin-infusion until GD20 or GD17, with sacrifice on GD20. Hypoglycaemia throughout gestation increased maternal corticosterone levels, which correlated with foetal levels. Growth plates displayed central histopathologic changes comprising disrupted cellular organisation, hypertrophic chondrocytes, and decreased cellular density; expression of pro-angiogenic factors, HIF-1α and VEGF-A increased in surrounding areas. Disproportionately decreased growth plate zone volumes and lower expression of the structural protein MATN-3 were seen, while bone ossification parameters were normal. Ending maternal/foetal hypoglycaemia on GD17 reduced incidence and severity of histopathologic changes and with normal growth plate volume. Compromised foetal skeletal development following maternal hypoglycaemia throughout gestation is hypothesised to result from corticosterone-induced hypoxia in growth plates, where hypoxia disrupts chondrocyte maturation and growth plate structure and volume, decreasing long bone growth. Maternal/foetal hypoglycaemia lasting only until GD17 attenuated these changes, suggesting a pivotal role of glucose in growth plate development.
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| 3. |
- Linder, Clara, et al.
(författare)
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Corrosion resistance of additively manufactured aluminium alloys for marine applications
- 2024
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Ingår i: npj Materials Degradation. - : Springer. - 2397-2106. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing opens new possibilities for designing light-weight structures using aluminium alloys. The microstructure of two Al alloys and their corrosion resistance in NaCl and natural seawater environments were investigated. The newly designed Al-Mn-Cr-Zr based alloy showed a higher corrosion resistance than reference AlSi10Mg alloy in both environments in as printed and heat-treated conditions. The corrosion initiated in the Al matrix along the precipitates in the alloys where the Volta potential difference was found the highest. The coarser microstructure and precipitate composition of the new Al-alloy led to the formation of a resistant passive film which extended the passivity region of the Al-Mn-Cr-Zr alloy compared to the AlSi10Mg alloy. The effect of heat treatment could be seen in the microstructure as more precipitates were found in between the melt pool boundaries, which affected the corrosion initiation and slightly the pitting resistance. Overall, this study shows that a newly designed Al-alloy for additive manufacturing has a suitable corrosion resistance for applications in marine environments.
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| 4. |
- Mellin, Pelle, et al.
(författare)
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Moisture content analysis of metal powders, using oven desorption followed by Karl Fischer titration
- 2018
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Ingår i: Euro PM 2018 Congress and Exhibition. - : European Powder Metallurgy Association (EPMA). - 9781899072507
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Konferensbidrag (refereegranskat)abstract
- In this paper, we use Oven Desorption followed by Karl Fischer Titration (KF), to measure moisture content in a newly opened PBF-LB Hasteloy X powder (we found 28.8 ppm), an PBF-EB powder (13.7 ppm) and a HIP powder (6.7 ppm). This method heats a powder sample inside a hermetically closed vial, in an oven. At the same time an inert gas flow enters, flushes out the evaporated water and exits the vial, via a double hollow needle. The gas-water mixture that exits is directed to the Karl Fischer Titration, where the evaporated moisture is quantified. Included is also a comparison with thermogravimetric analysis (TGA) and a climate chamber moisturization experiment of a PBF-LB HX powder followed by KF analysis. After the moisturization and KF analysis, the same powder was characterized in terms of oxygen content.
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| 5. |
- Mulvany, M J, et al.
(författare)
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Are isolated femoral resistance vessels or tail arteries good models for the hindquarter vasculature of spontaneously hypertensive rats?
- 1982
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Ingår i: Acta physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 116:3, s. 275-83
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the extent to which the properties of small arteries from the hindquarters of spontaneously hypertensive rats (SHRs) are consistent with the characteristics of perfused SHR hindquarter preparations (for which the relaxed vascular resistance, the reactivity and the sensitivity are reported to be increased). We have therefore compared the in vitro morphological and pharmacological properties of a femoral resistance vessel (i.d. ca 200 microns) and of the tail artery (i.d. ca 600 microns) from SHRs with those from control Wistar-Kyoto rats (WKYs). When relaxed, for any given wall tension, the internal circumference of the SHR resistance vessels was reduced, but that of the SHR tail artery was normal. When activated with 10 microM noradrenaline, the SHR resistance vessels had an increased calcium sensitivity, but the calcium sensitivity of the SHR tail arteries was normal. However, the maximum response of both types of SHR vessels was such that the vessels would have been able to contract against increased transmural pressure. The noradrenaline sensitivity of the SHR resistance vessels was normal but the SHR tail arteries had a decreased sensitivity. The results suggest that the femoral resistance vessel is in general a better model for the hindquarter vasculature than the tail artery.
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| 6. |
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| 7. |
- Mulvany, M J, et al.
(författare)
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Effect of sodium-potassium-dependent ATPase inhibition on noradrenaline-activated calcium sensitivity of mesenteric resistance vessels in adult spontaneously hypertensive rats.
- 1980
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Ingår i: Clinical science (London, England : 1979). - 0143-5221. ; 59 Suppl 6, s. 203s-205s
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Tidskriftsartikel (refereegranskat)abstract
- 1. We have investigated the noradrenaline-activated calcium sensitivity of 150 micrometer mesenteric resistance blood vessels from spontaneously hypertensive and control Wistar-Kyoto rats. 2. Under control conditions the spontaneously hypertensive rat blood vessels had a greater calcium sensitivity than the Wistar-Kyoto rat vessels. 3. In the presence of 1 mmol of ouabain/l, a treatment known to inhibit the sodium-potassium-dependent ATPase, the responses of the spontaneously hypertensive rat blood vessels were reduced more than those of the Wistar-Kyoto rat blood vessels, so that the responses of spontaneously hypertensive rat and Wistar-Kyoto rat blood vessels were then similar. 4. Similar results were obtained by removing external potassium, a procedure which should also inhibit the sodium-potassium-ATPase. 5. The results suggest that the greater noradrenaline-activated calcium sensitivity of spontaneously hypertensive rat blood vessels may be associated with an increased sodium-potassium-ATPase activity.
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| 8. |
- Schultheiss, Fredrik, et al.
(författare)
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Machinability of CuZn21Si3P brass
- 2016
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Ingår i: Materials Science and Technology. - : Informa UK Limited. - 1743-2847 .- 0267-0836. ; 32:17, s. 1744-1750
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Tidskriftsartikel (refereegranskat)abstract
- New brass alloys containing less or even no lead are being developed, decreasing the environmental impact of the material. One example of an alternative brass is CuZn21Si3P, which contains less than 0.09 wt-% Pb. The research presented in this article evaluates the machinability of CuZn21Si3P as compared to more common, lead-containing free-machining brasses. The results show a marked decrease in the machinability of CuZn21Si3P. When longitudinally turning CuZn21Si3P the cutting tool failed after 142 min of machining. This tool wear was to a large extent remedied through the use of a coating on the cutting tool. CuZn21Si3P appears as a viable substitute for lead-containing brasses, thus implying the possibility for improving the sustainability of modern production.
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| 9. |
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| 10. |
- Tam, Eric, 1980, et al.
(författare)
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Residual stress analysis of machined lead-free and lead-containing brasses
- 2016
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Ingår i: Materials Science and Technology. - : Informa UK Limited. - 1743-2847 .- 0267-0836. ; 32:17, s. 1789-1793
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Tidskriftsartikel (refereegranskat)abstract
- Legislations demand low lead content in drinking water and low lead leaching from the water supply facilities. Lead-free brass (LFB) can fit in. The benefits of such alloy are acknowledged in both functional and environmental points of view. The relatively high strength of LFB means that the process condition and residual stress generation can be different as compared to the conventional brass. In this study, residual stress generation for a LFB (CuZn21Si3P) and a lead-containing brass (CuZn39Pb3) in a face-turning experiment is studied. Besides stress analysis, structural characterisation is also conducted. Stress generation in the feed and cutting directions of two brasses is depicted. Machined topography is measured to evaluate the surface integrity in connection with the machining conditions.
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