| 220841. |
- Skjöldebrand, Charlotte, et al.
(författare)
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Si-Fe-C-N Coatings for Biomedical Applications : A Combinatorial Approach
- 2020
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 13:9
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic coatings may prolong the lifetime of joint implants. Certain ions and wear debris may however lead to negative biological effects. SiN-based materials may substantially reduce these effects, but still need optimization for the application. In this study, a combinatorial deposition method enabled an efficient evaluation of a range of Si-Fe-C-N coating compositions on the same sample. The results revealed compositional gradients of Si (26.0-33.9 at.%), Fe (9.6-20.9 at.%), C (8.2-13.9 at.%) and N (39.7-47.2 at.%), and low oxygen contaminations (0.3-0.6 at.%). The mechanical properties varied with a hardness (H) ranging between 13.7-17.3 GPa and an indentation modulus (M) between 190-212 GPa. Both H and M correlated with the Si (H and M increased as Si increased) and Fe (H and M decreased as Fe increased) content. A slightly columnar morphology was observed in cross-sections, as well as a surface roughness in the nm range. A cell study revealed adhering pre-osteogenic MC3T3 cells, with a morphology similar to that of cells seeded on a tissue culture plastic control. The investigated coatings could be considered for further investigation due to the ability to tune their mechanical properties while maintaining a smooth surface, together with their promising in vitro cell response.
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| 220842. |
- Skjöldebrand, Charlotte
(författare)
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Silicon nitride based coatings for biomedical implants
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Silicon nitride-based coatings have been proposed as a means to reduce the release of metal ions and debris from metallic implants. This reduction in combination with the biocompatible debris from silicon nitride could result in a less adverse immune response. However, as the literature shows, introduction of coatings for biomedical implants is challenging and so far only a few alternatives have made it to market.This thesis focuses on the composition of silicon nitride-based coatings deposited using physical vapor deposition methods and its effect on material properties. Firstly, the effect of the nitrogen content was evaluated through the deposition of silicon nitride coatings using different nitrogen gas flow and substrate temperatures in a HiPIMS system. The highest nitrogen content was obtained by selecting a nitrogen-to-argon gas flow of 0.3 and substrate temperature of 350°C. This in turn resulted in the highest hardness, 25.9±2.1 GPa, which could prevent surface damage and this could in turn prevent wear.Further investigation aimed at improving adhesion, deposition rate and dissolution behaviour, and therefore investigated the effect of specific alloying elements (Fe, C, Cr and Nb) on hardness, elastic modulus, surface properties, dissolution and biocompatibility. In order to screen a range of compositions in an efficient manner the coatings used for this were either SiFeCN or SiCrNbN deposited with compositional gradients. The silicon nitride coatings with the incorporation of Fe and C (SiFeCN coatings) were found to reduce ion release from the underlying substrate and the coating itself when compared to pure silicon nitride coatings. While the SiFeCN coatings reduced the ion release from the underlying metal, the coating surface showed clear signs of dissolution after 14 days in simulated body fluid. The coatings alloyed with Cr and Nb showed a further reduction in ion release from the coating itself. The ion release correlated negatively with the Cr content in the coating, which could be due to the passivating properties of the surface oxide of these coatings.The work presented here shows the importance of the nitrogen content and its influence on the mechanical properties of silicon nitride coatings. In addition, the studies reveal a possibility to tune coating properties such as dissolution rate, while maintaining the biocompatibility, through alloying with elements Fe, C, Cr and Nb. In summary, this thesis has contributed to a further understanding of the influence of composition on the behaviour of silicon nitride coatings intended for biomedical applications.
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| 220843. |
- Skjöldebrand, Charlotte, et al.
(författare)
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Tailoring the dissolution rate and in vitro cell response of silicon nitride coatings through combinatorial sputtering with chromium and niobium
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Ingår i: Biomaterials Science. - 2047-4830 .- 2047-4849.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Ceramic coatings have been widely investigated as a means to reduce wear and metallic ion release from joint implants. Silicon nitride-based coatings have been a topic of interest specifically due to their solubility in aqueous solutions. This could imply a reduced adverse immune response since the generated debris would dissolve. However, there are concerns regarding the dissolution rate and adhesion of these silicon nitride-based coatings.This study attempts to address the concern of dissolution rate as well as coating adhesion of silicon nitride coatings. We hypothesized that alloying with chromium and niobium would affect the adhesion, dissolution rate, and the resulting ion release and cell response to the coatings. A combinatorial approach was used to deposit sputtered coatings with compositional gradients both with and without a CrN interlayer. Compositional gradients were achieved for all the investigated elements: Si (38.6-46.9 at.%), Nb (2.2-4.6 at.%) and Cr (1.9-6.0 at.%). However, while the presence of an interlayer reduced the delamination during adhesion testing, the differences in composition in the top coating did not affect the adhesion. Nor did the top coating’s composition affect the surface roughness or the coatings’ inherent mechanical properties (elastic modulus and hardness). All coating compositions were associated with a low Co release from the underlying metal and points with a higher Cr content (4.3-6.0 at.%) gave an overall lower release of Si, Cr and Nb ions, possibly due to the formation of a stable oxide, which reduced the dissolution rate of the coating. Optimum chromium contents were furthermore found to give an enhanced in vitro fibroblast cell response.In conclusion, the results indicate a possibility to tailor the ion release rate, which lends promise to further investigations such as tribocorrosive tests towards a future biomedical application.
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| 220844. |
- Skjöldebrand, Charlotte, et al.
(författare)
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Tailoring the dissolution rate and in vitro cell response of silicon nitride coatings through combinatorial sputtering with chromium and niobium
- 2022
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Ingår i: Biomaterials Science. - : Royal Society of Chemistry (RSC). - 2047-4830 .- 2047-4849. ; 10:14, s. 3757-3769
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic coatings have been widely investigated as a means to reduce wear and metallic ion release from joint implants. Silicon nitride-based coatings have been a topic of interest specifically due to their solubility in aqueous solutions. This could imply a reduced adverse immune response since the generated debris would dissolve. However, there are concerns regarding the dissolution rate and adhesion of these silicon nitride-based coatings. This study attempts to address the concern of dissolution rate as well as coating adhesion of silicon nitride coatings. We hypothesized that alloying with chromium and niobium would affect the adhesion, dissolution rate, and the resulting ion release and cell response to the coatings. A combinatorial approach was used to deposit sputtered coatings with compositional gradients both with and without a CrN interlayer. Compositional gradients were achieved for all the investigated elements: Si (38.6-46.9 at%), Nb (2.2-4.6 at%) and Cr (1.9-6.0 at%). However, while the presence of an interlayer reduced the delamination during adhesion testing, the differences in composition in the top coating did not affect the adhesion. Nor did the top coating's composition affect the surface roughness or the coatings' inherent mechanical properties (elastic modulus and hardness). All coating compositions were associated with a low Co release from the underlying metal and points with a higher Cr content (4.3-6.0 at%) gave an overall lower release of Si, Cr and Nb ions, possibly due to the formation of a stable oxide, which reduced the dissolution rate of the coating. Optimum chromium contents were furthermore found to give an enhanced in vitro fibroblast cell viability. In conclusion, the results indicate a possibility to tailor the ion release rate, which lends promise to further investigations such as tribocorrosive tests towards a future biomedical application.
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| 220845. |
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| 220846. |
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| 220847. |
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Skłoting w Europie Środkowej i Rosji
- 2018
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- Skłoting – czyli zajmowanie pustostanów bez zgody ich właścicieli – jest od dawna przedmiotem akademickiej dyskusji. Jednak ten fenomen nie doczekał się jeszcze kompleksowego ujęcia z perspektywy Europy Środkowej. Niniejszy raport jest pierwszą tego rodzaju próbą w języku polskim. Autorzy tekstów nie tylko przedstawiają genealogie tego zjawiska w Budapeszcie, Wilnie, Pradze, Poznaniu, Warszawie czy Petersburgu, ale także podejmują debatę z aktualną literaturą przedmiotu, analizując to zjawisko z różnych perspektyw.
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| 220848. |
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| 220849. |
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| 220850. |
- Škoda, Radek, et al.
(författare)
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Gadolinite-(Nd), a new member of the gadolinite supergroup from Fe-REE deposits of Bastnäs-type.
- 2018
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Ingår i: Mineralogical magazine. - : Mineralogical Society. - 0026-461X .- 1471-8022. ; 82(S1), s. S133-S145
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Tidskriftsartikel (refereegranskat)abstract
- A new member of the gadolinite supergroup, gadolinite-(Nd), IMA2016-013, ideally Nd2FeBe2Si2O10, was found in the Malmkärra mine, ~3.5 km WSW of Norberg, south-central Sweden, where it occurs in association with fluorbritholite-(Ce), västmanlandite-(Ce), dollaseite-(Ce), bastnäsite-(Ce) and tremolite. Gadolinite-(Nd) forms anhedral grains up to 150 µm in size, commonly occurring as aggregates of olive green colour. The crystals are transparent with vitreous to adamantine lustre. Gadolinite-(Nd) is brittle with conchoidal fracture, no cleavage or parting was observed. It has a white streak, the Mohs hardness is 6.5–7 and the calculated density is 4.86 g cm–3. Optically, the mineral is weakly pleochroic in shades of olive green, biaxial (–), nα = 1.78(1), nβ(calc.) = 1.80, nγ = 1.81(1) measured in white light, 2V(meas.) = 62(3)°. Electron-microprobe and laser ablation inductively coupled plasma mass spectrometry analysis [in wt.%] provided SiO2 21.77, Y2O3 5.49, La2O3 2.78, Ce2 O3 14.04, Pr2O3 3.28, Nd2O3 19.27, Sm2O3 5.30, Eu2O3 0.24, Gd2O3 4.10, Tb2O3 0.36, Dy2O3 1.32, Ho2O3 0.18, Er2O3 0.38, MgO 0.51, CaO 0.14, MnO 0.10, FeO 10.62, B2O3 0.10, BeOcalc. 8.99, H2Ocalc. 0.55 and total 99.52 giving the following empirical formula (based on 2 Si): (Nd0.632 Ce0.472Y0.268Sm0.168Gd0.125Pr0.110La0.094Dy0.039Ca0.014Er0.011Tb0.011Eu0.008Ho0.008)∑1.957(Fe0.816Mg0.070Mn0.008)∑0.894(Be1.984B0.016)∑2.000Si2O9.660OH0.337. A weak Raman vibration band at ~3525 cm–1 confirms the presence of water in the structure. Gadolinite-(Nd) is monoclinic, P21/c, with a = 4.8216(3) Å, b = 7.6985(4) Å, c = 10.1362(6) Å, β = 90.234(4)°, V = 376.24(6) Å3 and Z = 2. The strongest X-ray diffraction lines are [dobs in Å (hkl) Irel]: 4.830 (100) 72, 3.603 (021) 37, 3.191(-112) 52, 3.097 (013) 35, 2.888 (121) 100, 2.607(113) 49, 2.412 (200) 24. Along with the Malmkärra mine, gadolinite-(Nd) was also recorded also at Johannagruvan and Nya Bastnäs. The minerals of the gadolinite subgroup together with fluorbritholite-(Ce) incorporate the highest fraction of medium-to-heavy rare-earth elements among associated rare-earth element minerals in the Malmkärra mine and possibly in all Bastnäs-type deposits.
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