No description available.

No description available.

Delayed or impaired bone healing occurs in 5-10% of all fractures, yet cost effective solutions to enhance the healing process are limited. Lithium, a current treatment for bipolar disorder, is not clinically indicated for use in fracture management, but has been reported to positively influence bone biology. The objective of this study was to identify lithium administration parameters that maximize bone healing in a preclinical, rodent femur fracture model. Using a three factor, two level, design of experiments (DOE) approach, bone healing was assessed through mechanical testing and μCT-image analysis. Significant improvements in healing were found at a low dose, later onset, longer duration treatment combination, with onset identified as the most influential parameter. The positive results from this DOE screening focuses the optimization phase towards further investigation of the onset component of treatment, and forms a crucial foundation for future studies evaluating the role of lithium in fracture healing.

Delayed or impaired bone healing occurs in 5-10% of all fractures, yet cost effective solutions to enhance the healing process are limited. Lithium, a current treatment for bipolar disorder, is not clinically indicated for use in fracture management, but has been reported to positively influence bone biology. The objective of this study was to identify lithium administration parameters that maximize bone healing in a preclinical, rodent femur fracture model. Using a three factor, two level, design of experiments (DOE) approach, bone healing was assessed through mechanical testing and μCT-image analysis. Significant improvements in healing were found at a low dose, later onset, longer duration treatment combination, with onset identified as the most influential parameter. The positive results from this DOE screening focuses the optimization phase towards further investigation of the onset component of treatment, and forms a crucial foundation for future studies evaluating the role of lithium in fracture healing.

No description available.

Eutectoid steel strips are designed for the production of parts for intensive use such as clutches, seat slides, and springs as they exhibit<p>excellent strength levels and wear resistance. These properties arise from the unique morphology of lamellar pearlite which can be considered<p>as a self-laminated nanoscale composite. However, a spheroidization annealing step is nowadays necessary to improve the cold forming properties before further cold rolling steps.<p>This thesis is aimed at improving the tensile ductility of the hot rolled products of eutectoid composition in order to eliminate the intermediate<p>annealing step. Two strategies are proposed.<p>The first is to transpose the concept of controlled rolling developed for HSLA to<p>eutectoid steels. Through a strict adjustment of the austenite processing and of the cooling strategy, it is possible to improve the ductility<p>of the final lamellar microstructure. The way the processing parameters influence the hot deformation of austenite, the eutectoid transformation and of the subsequent spheroidization annealing is deeply<p>investigated. It is found that refinement and pancaking of austenite<p>is beneficial as it reduces the pearlite block size improving the total<p>tensile elongation. Accelerated cooling is of paramount importance to<p>achieve fine Interlamellar spacing (ILS), which lead to high strength<p>levels and accelerate spheroidization during subsequent annealing.<p>The second approach involves intercritical or warm deformation. Warm processing of eutectoid steels is first explored by torsion testing<p>and then up-scaled to a pilot rolling-line. The interactions between thermomechanical parameters, rolling forces generated and microstructural<p>evolution are carefully scrutinized. During concurrent hot deformation, spheroidization of cementite takes place almost instantaneously<p>in both torsion and rolling. The restoration processes occurring in the ferrite matrix depends on the strain path and the strain rates. Low strain rates (0,1 s−1) and simple shear promotes the formation of a recrystallized-like HABs network of about 3μm in size.<p>Plane strain compression and high strain rates (10 s−1) leads to the formation of a typical recovered dislocation substructure (LABs) of 1μm in size. During annealing, no recrystallization occurs and the LABs substructure remains stable. This substructure influences drammatically the mechanical properties: the strength is very high and the work-hardening behavior is poor due to high recovery rate in the region close to the LABs. However, due to the presence of spheroidized<p>cementite particles the ductility of warm rolled eutectoid steels is higher than that of ultra fine grained low carbon steels. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished