Defect-mediated ferromagnetism in ZnO:Mn nanorods

In this work, the structural, chemical and magnetic properties of ZnO:Mn nanorods were investigated. Firstly, well-aligned ZnO nanorods with their long axis parallel to the crystalline c-axis were successfully grown by the vapor phase transport technique on Si substrates coated with a ZnO buffer layer. Mn metal was then diffused into these nanorods at different temperatures in vacuum. From SEM results, ZnO:Mn nanorods were observed to have diameters of ~100 nm and lengths of 4 µm. XPS analysis showed that the Mn dopant substituted into the ZnO matrix with a valence state of +2. Magnetic measurements performed at room temperature revealed that undoped ZnO nanorods exhibit ferromagnetic behavior which may be related to oxygen vacancy defect-mediated d0 ferromagnetism. ZnO:Mn samples were seen to show an excess room temperature ferromagnetism that is attributed to the presence of oxygen vacancy defects forming bound magnetic polarons involving Mn

Body mass index and complications following major gastrointestinal surgery: A prospective, international cohort study and meta-analysis

Aim Previous studies reported conflicting evidence on the effects of obesity on outcomes after gastrointestinal surgery. The aims of this study were to explore the relationship of obesity with major postoperative complications in an international cohort and to present a metaanalysis of all available prospective data. Methods This prospective, multicentre study included adults undergoing both elective and emergency gastrointestinal resection, reversal of stoma or formation of stoma. The primary end-point was 30-day major complications (Clavien–Dindo Grades III–V). A systematic search was undertaken for studies assessing the relationship between obesity and major complications after gastrointestinal surgery. Individual patient meta-analysis was used to analyse pooled results. Results This study included 2519 patients across 127 centres, of whom 560 (22.2%) were obese. Unadjusted major complication rates were lower in obese vs normal weight patients (13.0% vs 16.2%, respectively), but this did not reach statistical significance (P = 0.863) on multivariate analysis for patients having surgery for either malignant or benign conditions. Individual patient meta-analysis demonstrated that obese patients undergoing surgery formalignancy were at increased risk of major complications (OR 2.10, 95% CI 1.49–2.96, P < 0.001), whereas obese patients undergoing surgery for benign indications were at decreased risk (OR 0.59, 95% CI 0.46–0.75, P < 0.001) compared to normal weight patients. Conclusions In our international data, obesity was not found to be associated with major complications following gastrointestinal surgery. Meta-analysis of available prospective data made a novel finding of obesity being associated with different outcomes depending on whether patients were undergoing surgery for benign or malignant disease