RESUMEN
The exchange coupling of a single spin localized at the central ion of Cu-tetraazaporphyrin on a magnetite(100) surface has been studied using x-ray magnetic circular dichroism (XMCD). Sum rule analysis of the XMCD spectra results in Cu spin and orbital magnetic moments as a function of the applied external field at low temperatures (20 K). The exchange coupling is positive for magnetization direction perpendicular to the surface (ferromagnetic) while it is negative for in-plane magnetization direction (antiferromagnetic). We attribute the anisotropy of the Heisenberg exchange coupling to an orbitally dependent exchange Hamiltonian.
RESUMEN
We examined 25 different threaded cups using a specific biomechanical procedure. Great differences between the tested cups concerning their biomechanical parameters could be found. There is some evidence that the design of several cups might be inappropriate for stable acetabular fixation, and this may be the reason for early loosening. The new procedure is the first to allow biomechanical assessment of threaded cups by using quantified data, which correspond to long-term stability of the cup.
Asunto(s)
Prótesis de Cadera , Acetábulo , Fenómenos Biomecánicos , Humanos , Técnicas In Vitro , Diseño de Prótesis , Propiedades de Superficie , TorqueRESUMEN
Two new methods now allow the systematic examination of the morphology and micropathology of the initial lymphatics (lymph sinuses and precollectors) in human skin biopsy specimens under the scanning electron microscope. Pertinent studies and findings in the intact skin of anesthetized pigs demonstrate the standard quality of the biopsy preparations. The following are new findings made with these methods: in the skin of the human head, both the lymph sinuses and the precollectors extend as far as the epidermis. The opening apparatus of these vessels consists not only of anchoring filaments and interendothelial openings, but also of endothelial bridges and trabeculae. The interendothelial openings can be present in three types of transformation (Type I-III). As part of these studies, an attempt was made to standardize the lymphological nomenclature so that it would be acceptable to both anatomists and clinicians.