87 research outputs found

    Influence of a Pronounced Pre-Deformation on the Attachment of Melt Droplets and the Fatigue Behavior of Laser-Cut AISI 304

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    Laser cutting is a suitable manufacturing method for generating complex geometries for sheet metal components. However, their cyclic load capacity is reduced compared to, for example, milled components. This is due to the influence of the laser-cut edge, whose characteristic features act as crack initiation sites, especially resolidified material in the form of burr and melt droplets. Since sheet metal components are often formed into their final geometry after cutting, another important factor influencing fatigue behavior is the effect of the forming process on the laser-cut edge. In particular, the effect of high degrees of deformation has not yet been researched in detail. Accordingly, sheets of AISI 304 were processed by laser cutting and pre-deformed. In the process, α’-martensite content was set to be comparable despite different degrees of deformation. It was found that deformation to high elongations caused a large part of the melt adhesions to fall off, but those still attaching were partially detached and thus formed an initial notch for crack initiation. This significantly lowered the fatigue strength

    In-situ study of growth of carbon nanotube forests on conductive CoSi<sub>2</sub> support

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    The growth of high density vertically aligned carbon nanotube forests on conductive CoSi2 substrate layers is characterized by in situ x-ray photoemission spectroscopy and x-ray diffraction. We use in situ silicidation to transform as loaded, low conductivity CoSi supports to highly conductive CoSi2 during nanotube growth. These cobalt silicide films are found to be stable against oxidation and carbide formation during growth and act as an excellent metallic support for growth of aligned nanotubes, resembling the growth on the insulating Fe/Al2O3 benchmark system. The good catalytic activity is attributed to interfacial reactions of the Fe catalyst particles with the underlying CoSi2 support. We obtain ohmic conduction from the support layer to the carbon nanotube forest

    Personal preference, experience, intuition and school of surgery dominate the use of wound drainage in dermatosurgery

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    Hintergrund Die Verwendung von Drainagesystemen in der Dermatochirurgie erfolgt bislang ohne evidenzbasierte Daten. Indikationen, Komplikationen und Kontraindikationen werden traditionell von Operateur zu Operateur weitergegeben, sind jedoch bisher nicht definiert. Methodik Es wurde eine internetbasierte Umfrage erstellt und unter den Mitgliedern der DGDC e. V. (Deutsche Gesellschaft für Dermatochirurgie e. V.) ausgesandt. Abgefragt wurden das allgemeine Behandlungsverhalten im deutschsprachigen Raum in Bezug auf die Anwendung der Wunddrainage nach dermatologischen Operationen sowie die Nutzungsgewohnheiten und Erfahrungen der Kollegen mit Drainage-assoziierten Komplikationen. Ergebnisse Es haben 12,73 % der angeschriebenen DGDC-Mitglieder den Fragebogen beantwortet. Drainagen werden überwiegend im klinischen Umfeld eingesetzt, es werden alle abgefragten Drainagesysteme verwendet. Ausmaß und Komplexität des Eingriffs sind die wesentlichen Kriterien bei der Indikationsstellung. Der Einsatz von Drainagen ist abhängig vom Alter des Teilnehmers und erfolgt mehrheitlich bei Patienten, bei denen Komplikationen im postoperativen Verlauf erwartet werden (Adipositas, Nikotinabusus, Diabetiker). Diskussion Zusammenfassend verwendet die Mehrzahl der Teilnehmer Wunddrainagen und dies mehrheitlich intuitiv. Einheitliche fixe evidenzbasierte Parameter rund um die Verwendung von Wunddrainagen fehlen. Bei der Beurteilung der Notwendigkeit einer Wunddrainage scheint ein individuell unterschiedlich ausgeprägtes Sicherheitsbedürfnis bei den einen und „eminenzbasiertes“ Handeln bei den anderen Dermatochirurgen eine große Rolle zu spielen.Background The use of drainage systems in dermatosurgery has so far been carried out without evidence-based data. The indications, complications and contraindications are traditionally passed on from surgeon to surgeon but have so far not been defined. Method An Internet-based survey was created and sent out to members of the German Society for Dermatosurgery (DGDC). The questions were on the general treatment approach in German language countries with reference to the use of wound drainage following dermatological operations as well as the utilization habits and experiences with drainage-associated complications. Results Of the DGDC members contacted 12.73% completed the questionnaire. Drainages were predominantly used in the clinical environment and all drainage systems in question were used. The extent and complexity of the intervention were essential criteria when evaluating the indications. The use of drainages was dependent on the age of the participant and mostly carried out in patients where complications in the postoperative course were to be expected (e.g. obesity, nicotine use, diabetes). Conclusion In summary, the majority of the participants used wound drainages and mostly intuitively. Uniform and fixed evidence-based parameters for the use of wound drainages are lacking. In the assessment of the necessity for a wound drainage, an individually expressed need of safety seems to play a large role for some dermatosurgeons and an eminence-based action for others

    Branch Retinal Vein Occlusion: Pathogenesis, Visual Prognosis, and Treatment Modalities

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    In branch retinal vein occlusion (BRVO), abnormal arteriovenous crossing with vein compression, degenerative changes of the vessel wall and abnormal hematological factors constitute the primary mechanism of vessel occlusion. In general, BRVO has a good prognosis: 50–60% of eyes are reported to have a final visual acuity (VA) of 20/40 or better even without treatment. One important prognostic factor for final VA appears to be the initial VA. Grid laser photocoagulation is an established treatment for macular edema in a particular group of patients with BRVO, while promising results for this condition are shown by intravitreal application of steroids or new vascular endothelial growth factor inhibitors. Vitrectomy with or without arteriovenous sheathotomy combined with removal of the internal limiting membrane may improve vision in eyes with macular edema which are unresponsive to or ineligible for laser treatment

    Development of a Unifying Target and Consensus Indicators for Global Surgical Systems Strengthening: Proposed by the Global Alliance for Surgery, Obstetric, Trauma, and Anaesthesia Care (The G4 Alliance)

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    After decades on the margins of primary health care, surgical and anaesthesia care is gaining increasing priority within the global development arena. The 2015 publications of the Disease Control Priorities third edition on Essential Surgery and the Lancet Commission on Global Surgery created a compelling evidenced-based argument for the fundamental role of surgery and anaesthesia within cost-effective health systems strengthening global strategy. The launch of the Global Alliance for Surgical, Obstetric, Trauma, and Anaesthesia Care in 2015 has further coordinated efforts to build priority for surgical care and anaesthesia. These combined efforts culminated in the approval of a World Health Assembly resolution recognizing the role of surgical care and anaesthesia as part of universal health coverage. Momentum gained from these milestones highlights the need to identify consensus goals, targets and indicators to guide policy implementation and track progress at the national level. Through an open consultative process that incorporated input from stakeholders from around the globe, a global target calling for safe surgical and anaesthesia care for 80% of the world by 2030 was proposed. In order to achieve this target, we also propose 15 consensus indicators that build on existing surgical systems metrics and expand the ability to prioritize surgical systems strengthening around the world

    Development of a Unifying Target and Consensus Indicators for Global Surgical Systems Strengthening: Proposed by the Global Alliance for Surgery, Obstetric, Trauma, and Anaesthesia Care (The G4 Alliance)

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    Epidemiologia do carcinoma basocelular

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