RESUMEN
The layered-ruthenate family of materials possess an intricate interplay of structural, electronic and magnetic degrees of freedom that yields a plethora of delicately balanced ground states. This is exemplified by Ca3Ru2O7, which hosts a coupled transition in which the lattice parameters jump, the Fermi surface partially gaps and the spins undergo a 90∘ in-plane reorientation. Here, we show how the transition is driven by a lattice strain that tunes the electronic bandwidth. We apply uniaxial stress to single crystals of Ca3Ru2O7, using neutron and resonant x-ray scattering to simultaneously probe the structural and magnetic responses. These measurements demonstrate that the transition can be driven by externally induced strain, stimulating the development of a theoretical model in which an internal strain is generated self-consistently to lower the electronic energy. We understand the strain to act by modifying tilts and rotations of the RuO6 octahedra, which directly influences the nearest-neighbour hopping. Our results offer a blueprint for uncovering the driving force behind coupled phase transitions, as well as a route to controlling them.
RESUMEN
PURPOSE: Perfusion techniques on cadavers are heterogeneous and imperfect. The objective of this study was to improve the existing circulation model for surgical simulation on cadavers. METHODS: We used a three-step experimental approach. The first part of the experiment tested two variables: the type of circuit and the use of a heater for perfusion. The second approach evaluated two parameters: the injection fluid and the type of body conditioning (embalmed or freshly dead prepared using different washing techniques). The third one was an improvement on the best circulation obtained, which focused on the injection fluid. To compare the realism of these different techniques, we constructed a score with realism parameters: the volume of return flow, the presence of peripheral venous return and the perfusion of abdominal arteries. RESULTS: We found that the use of a heater seemed to improve the perfusion, while performing an arteriovenous bypass did not seem very effective. A correlation rate of 0.84 was found between the realism score and the injected fluid chosen. The best score (4/6) was found for a non-embalmed body with a low-pressure washing technique using a gelatin-based liquid at a concentration of 4 g/L for circulation. Scores obtained using embalmed bodies for both injection fluids for high-pressure washing or for 8-g/L gelatin injection fluid did not exceed 3/6. CONCLUSIONS: We showed that using a non-embalmed body with low-pressure washing and a 4-g/L gelatin-based fluid was the most effective technique for cadaver perfusion.
