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- Filho, Luimar, et al.
(författare)
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The effect of N, C, Cr, and Nb content on silicon nitride coatings for joint applications
- 2020
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 13:8
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic coatings are an alternative to achieve or maintain a high wear resistance of metallic surfaces, and simultaneously allow for a reduction in metal ion release. Silicon nitride based (SiNx) coatings deposited by high power impulse magnetron sputtering (HiPIMS) have shown potential for use in joint implants seen from an improved chemical stability in combination with a good adhesion. The aim of this study was to investigate the effect of N, C, Cr and Nb content on the tribocorrosive performance of 3.7 to 8.8 µm thick SiNx coatings deposited by HiPIMS onto CoCrMo discs to improve the mechanical properties and/or chemical stability of SiNx .Coating composition was evaluated by X-ray photoelectron spectroscopy (XPS) and the surface roughness by Vertical Scanning Interferometry (VSI). Hardness and Young’s modulus were investigated by nanoindentation and coating adhesion was measured by scratch tests. Multidirectional wear tests against UHMWPE pins were performed for 2 million cycles in bovine serum solution (25%) at 37°C, at an estimated contact pressure of 2.1 MPa.Coatings with a relatively low hardness tended to fail earlier in the wear test, due to chemical reactions and eventually dissolution, accelerated by the tribological contact. In fact, while no definite correlation could be observed between coating composition (N: 42.6-55.5 at%, C: 0-25.7 at%, Cr: 0 or 12.8 at%, and Nb: 0-24.5 at%) and wear performance, it was apparent that high-purity and/or -density coatings (i.e. low oxygen content and high nitrogen content) were desirable to prevent coating and/or counter surface wear. Coatings deposited with a higher energy fulfilled the target profile in terms of low surface roughness (Ra<20nm), adequate adhesion (Lc2>30N), chemical stability over time in the tribocorrosive environment, as well as low polymer wear, presenting potential for a future application in joint bearings.
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- Axling, Ulrika, et al.
(författare)
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Effects of rose hip intake on risk markers of type 2 diabetes and cardiovascular disease: a randomized, double-blind, cross-over investigation in obese persons.
- 2012
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Ingår i: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 1476-5640 .- 0954-3007. ; 66:5, s. 585-590
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/OBJECTIVES:In studies performed in mice, rose hip powder has been shown to both prevent and reverse high-fat diet-induced obesity and glucose intolerance as well as reduce plasma levels of cholesterol. The aim of this study was to investigate whether daily intake of rose hip powder over 6 weeks exerts beneficial metabolic effects in obese individuals.SUBJECTS/METHODS:A total of 31 obese individuals with normal or impaired glucose tolerance were enrolled in a randomized, double-blind, cross-over study in which metabolic effects of daily intake of a rose hip powder drink over 6 weeks was compared with a control drink. Body weight, glucose tolerance, blood pressure, blood lipids and markers of inflammation were assessed in the subjects.RESULTS:In comparison with the control drink, 6 weeks of daily consumption of the rose hip drink resulted in a significant reduction of systolic blood pressure (-3.4%; P=0.021), total plasma cholesterol (-4.9%; P=0.0018), low-density lipoprotein (LDL) cholesterol (-6.0%; P=0.012) and LDL/HDL ratio (-6.5%; P=0.041). The Reynolds risk assessment score for cardiovascular disease was decreased in the rose hip group compared with the control group (-17%; P=0.007). Body weight, diastolic blood pressure, glucose tolerance, and plasma levels of high-density lipoprotein (HDL) cholesterol, triglycerides, incretins and markers of inflammation did not differ between the two groups.CONCLUSIONS:Daily consumption of 40 g of rose hip powder for 6 weeks can significantly reduce cardiovascular risk in obese people through lowering of systolic blood pressure and plasma cholesterol levels.European Journal of Clinical Nutrition advance online publication, 14 December 2011; doi:10.1038/ejcn.2011.203.
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- Carlsson, Georg, et al.
(författare)
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N-2 fixation in three perennial Trifolium species in experimental grasslands of varied plant species richness and composition
- 2009
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Ingår i: Plant Ecology. - : Springer Science and Business Media LLC. - 1385-0237 .- 1573-5052. ; 205, s. 87-104
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Tidskriftsartikel (refereegranskat)abstract
- This study is the first to investigate quantitative effects of plant community composition and diversity on N-2 fixation in legumes. N-2 fixation in three perennial Trifolium species grown in field plots with varied number of neighbouring species was evaluated with the N-15 natural abundance method (two field sites, several growing seasons, no N addition) and the isotope dilution method (one site, one growing season, 5 g N m(-2)). The proportion of plant N derived from N-2 fixation, pNdfa, was generally high, but the N addition decreased pNdfa, especially in species-poor communities. Also following N addition, the presence of grasses in species-rich communities increased pNdfa in T. hybridum and T. repens L., while legume abundance had the opposite effect. In T. repens, competition for light from grasses appeared to limit growth and thereby the amount of N-2 fixed at the plant level, expressed as mg N-2 fixed per sown seed. We conclude that the occurrence of diversity effects seems to be largely context dependent, with soil N availability being a major determinant, and that species composition and functional traits are more important than species richness regarding how neighbouring plant species influence N-2 fixation in legumes.
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