Elucidation of the helical spin structure of FeAs

We present the results of resonant x-ray scattering measurements and electronic structure calculations on the monoarsenide FeAs. We elucidate details of the magnetic structure, showing the ratio of ellipticity of the spin helix is larger than previously thought, at 2.58(3), and reveal both a right-handed chirality and an out-of-plane component of the magnetic moments in the spin helix. We find that electronic structure calculations and analysis of the spin-orbit interaction are able to qualitatively account for this canting

Implantation of a polycaprolactone scaffold with subchondral bone anchoring ameliorates nodules formation and other tissue alterations

PURPOSE: Articular cartilage has limited repair capacity. Two different implant devices for articular cartilage regeneration were tested in vivo in a sheep model to evaluate the effect of subchondral bone anchoring for tissue repair. METHODS: The implants were placed with press-fit technique in a cartilage defect after microfracture surgery in the femoral condyle of the knee joint of the sheep and histologic and mechanical evaluation was done 4.5 months later. The first group consisted of a biodegradable polycaprolactone (PCL) scaffold with double porosity. The second test group consisted of a PCL scaffold attached to a poly(L-lactic acid) (PLLA) pin anchored to the subchondral bone. RESULTS: For both groups most of the defects (75%) showed an articular surface that was completely or almost completely repaired with a neotissue. Nevertheless, the surface had a rougher appearance than controls and the repair tissue was immature. In the trials with solely scaffold implantation, severe subchondral bone alterations were seen with many large nodular formations. These alterations were ameliorated when implanting the scaffold with a subchondral bone anchoring pin. DISCUSSIONS: The results show that tissue repair is improved by implanting a PCL scaffold compared to solely microfracture surgery, and most importantly, that subchondral bone alterations, normally seen after microfracture surgery, were partially prevented when implanting the PCL scaffold with a fixation system to the subchondral bone.This work was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2013-46467-C4-R (including the FEDER financial support). CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008–2011, Iniciativa Ingenio 2010, Consolider Program. CIBER actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund