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4 results on '"Bortel, Emely Lea"'

3. Development of a synthetic synovial fluid for tribological testing

Author

Bortel, Emely Lea, Charbonnier, Baptiste, Heuberger, Roman, Bortel, Emely Lea, Charbonnier, Baptiste, and Heuberger, Roman

Abstract

Wear tests of joint prostheses are usually performed using bovine calf serum. The results from different laboratories are hardly ever comparable as, for example, the protein concentration and the protein composition of the serum-based test liquids vary. In addition, the viscosity of these test liquids is similar to that of water and does not match the more viscous synovial fluid. The present work was aimed at developing a synthetic synovial fluid as an alternative to the existing test liquids. Improved consistency and reproducibility of results at a similar price were required. Hyaluronic acid (HA), the lyophilized proteins bovine serum albumin (BSA) and immunoglobulin G (IgG), the phospholipid lecithin (PL) and salts were applied in a stepwise approach to replace the actually used test liquid based on newborn calf serum. The in vitro results obtained with ultra-high-molecular-weight polyethylene (UHMWPE) pins sliding against CoCrMo discs revealed that the developed synthetic synovial fluid fulfils the set requirements: increase of viscosity, reasonable cost, improved consistency and wear particles which resemble the ones found in vivo. The developed synthetic synovial fluid with 3 g/L HA, 19 g/L BSA, 11 g/L IgG, 0.1 g/L PL and Ringer solution is a more realistic alternative to the used serum-based test liquid.

Published
2019

4. Size-dependent elastic-inelastic behavior of enamel over millimeter and nanometer length scales

Author

Ang, Siang Fung, Bortel, Emely Lea, Swain, Michael V., Klocke, Arndt, and Schneider, Gerold A.

Subjects
nanoindentation, Ingenieurwissenschaften [620], mechanical properties, hierarchische Struktur, 51.60:Keramische Werkstoffe, Hartstoffe, Druckversuch, stomatognathic system, Eindruckversuch, 51.60, elastic-inelastic transition, Sonstige Werkstoffe [51.79], size-dependent, Zahnschmelz, Keramische Werkstoffe, Hartstoffe [51.60], Quantitative Biology::Neurons and Cognition, 51.30:Werkstoffpr��fung, Werkstoffuntersuchung, enamel, Werkstoffkunde: Sonstiges [51.99], Zahntechnik, elastisch-inelastischer Übergang, 620: Ingenieurwissenschaften, Werkstoffprüfung, Werkstoffuntersuchung [51.30], 51.99:Werkstoffkunde: Sonstiges, 51.30, 51.99, 51.79:Sonstige Werkstoffe, ddc:620, elastisch-inelastischer ��bergang, 51.79, Mechanische Eigenschaften
Abstract

The microstructure of enamel like most biological tissues has a hierarchical structure which determines their mechanical behavior. However, current studies of the mechanical behavior of enamel lack a systematic investigation of these hierarchical length scales. In this study, we performed macroscopic uni-axial compression tests and the spherical indentation with different indenter radii to probe enamel���s elastic/inelastic transition over four hierarchical length scales, namely: ���bulk enamel��� (mm), ���multiple-rod��� (10���s ��m), intra-rod��� (100���s nm with multiple crystallites) and finally ���single-crystallite��� (10���s nm with an area of approximately one hydroxyapatite crystallite). The enamel���s elastic/inelastic transitions were observed at 0.4-17GPa depending on the length scale and were compared with the values of synthetic hydroxyapatite crystallites. The elastic limit of a material is important as it provides insights into the deformability of the material before fracture. At the smallest investigated length scale (contact radius ~20nm), elastic limit is followed by plastic deformation. At the largest investigated length scale (contact size ~1mm), only elastic then micro-crack induced response was observed. A map of elastic/inelastic regions of enamel from millimeter to nanometer length scale is presented. Possible underlying mechanisms are also discussed.

Published
2010
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