Influence of carbon diffusion on microstructure and wear behaviour of duplex stainless steel surface layers on lamellar grey cast iron

Surface welding with duplex stainless steel was performed to enhance the wear and corrosion properties of grey cast iron, which is used as material for applications as pump components in maritime and chemical environments. The method used for surface welding and the corresponding process parameters determine the chemical composition and microstructure, which both determine the corrosion and wear properties of the surface layer. High heat input leads to high chemical dilution and thus, reduced corrosion resistance. Slow cooling rates, which are recommended for welding of grey cast iron components, facilitate the formation of carbides in the fusion zone of the chromium‐rich duplex stainless steel surface layer. On the one hand, carbides lead to increased hardness and thus, improved wear resistance of the surface layers. On the other hand, carbides and high chemical dilution rates reduce the corrosion resistance and therefore should be avoided. Under high cooling rates, the risk of cracking in the heat affected zone of the grey cast iron increases due to martensitic phase transformations. The paper describes the correlation of process parameters, microstructure and chemical composition with a focus on carbon diffusion and carbide formation, ever considering the effect on the wear behaviour in an oscillation tribometer and under erosion‐corrosion conditions

Towards a standardization of biomethane potential tests

8 PáginasProduction of biogas from different organic materials is a most interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. A workshop was held in June 2015 in Leysin Switzerland to agree on common solutions to the conundrum of inconsistent BMP test results. A discussion covers actions and criteria that are considered compulsory ito accept and validate a BMP test result; and recommendations concerning the inoculum substrate test setup and data analysis and reporting ito obtain test results that can be validated and reproduced.The workshop in Leysin, Switzerland, has been financed by the Swiss Federal Office for Energy, and co-sponsored by Bioprocess Control Sweden AB, Lund, Sweden. The authors thank Alexandra Maria Murray for editing the English

ein strukturierter OP-Besuch für vorklinische Studierende

Background: During the preclinical period German medical students have little or no opportunities to make experiences in the operating theatre (OT); later these experiences are often provided in an unstructured way.Purpose: The course "OT visit for preclinical students" is planned to improve vertical integration within a structured learning environment. We checked the project for feasibility, acceptance and flaws. Method: The course consists of 3 parts: 1. Pre-course assignments. 2. The OT visit. 3. A short reflection and feedback.Results: 36 preclinical students participated in the course, we received oral feedback from all students and 24 written evaluation forms. Overall acceptance both by teachers and students was good or very good. We found the course to be feasible both for teachers and students. Some students found the pre-course assignments only "satisfactory" and some found the demands "slightly excessive". Conclusion: In terms of acceptance and feasibility, we should implement the course into our regular curriculum. We have to improve our pre-course assignments and offer some help for handling the huge amount of new impressions in the OT. We should look for a way to offer structured OT visits for a higher number of students.Hintergrund: Im vorklinischen Abschnitt haben Medizinstudierende in Deutschland kaum Gelegenheit, OP-Erfahrungen zu machen; später werden diese meist in unstrukturierter Form vermittelt.Vorhaben: Der Kurs "OP Besuch für Vorkliniker" soll die vertikale Integration in strukturierter Lernumgebung verbessern. Wir prüften Machbarkeit, Akzeptanz und mögliche Schwachpunkte.Methode: Der Kurs besteht aus 3 Teilen. 1. Vorbereitungsaufgaben. 2. OP-Besuch. 3. Kurze Reflexion und Feedback.Ergebnisse: 36 vorklinische Studierende nahmen teil, wir erhielten mündliches Feedback von allen und schriftliches Feedback von 24 Studierenden. Insgesamt war die Akzeptanz gut bis sehr gut. Die Machbarkeit für Studierende wie für Lehrer ist gegeben. Einige Studierende fanden die Vorbereitungsaufgaben nur "zufrieden stellend", und einige fanden die Anforderungen "etwas zu hoch".Schlussfolgerung: Aufgrund seiner Akzeptanz und Machbarkeit sollte der Kurs im Curriculum regelmäßig angeboten werden. Die Vorbereitungsaufgaben müssen noch optimiert werden. Wir müssen Hilfestellung anbieten, damit die große Menge neuer Eindrücke im OP besser verarbeitet werden kann. Wir sollten den Kurs einer größeren Studierendenzahl anbieten können

Report on planning comparison of VMAT, IMRT and helical tomotherapy for the ESCALOX-trial pre-study

Background: The ESCALOX trial was designed as a multicenter, randomized prospective dose escalation study for head and neck cancer. Therefore, feasibility of treatment planning via diferent treatment planning systems (TPS) and radiotherapy (RT) techniques is essential. We hypothesized the comparability of dose distributions for simultaneous integrated boost (SIB) volumes respecting the constraints by diferent TPS and RT techniques. Methods: CT data sets of the frst six patients (all male, mean age: 61.3 years) of the pre-study (up to 77 Gy) were used for comparison of IMRT, VMAT, and helical tomotherapy (HT). Oropharynx was the primary tumor location. Normalization of the three step SIB (77 Gy, 70 Gy, 56 Gy) was D95%=77 Gy. Coverage (CVF), healthy tissue conformity index (HTCI), conformation number (CN), and dose homogeneity (HI) were compared for PTVs and conformation index (COIN) for parotids. Results: All RT techniques achieved good coverage. For SIB77Gy, CVF was best for IMRT and VMAT, HT achieved highest CN followed by VMAT and IMRT. HT reached good HTCI value, and HI compared to both other techniques. For SIB70Gy, CVF was best by IMRT. HTCI favored HT, consequently CN as well. HI was slightly better for HT. For SIB56Gy, CVF resulted comparably. Conformity favors VMAT as seen by HTCI and CN. Dmean of ipsilateral and contralateral parotids favor HT. Conclusion: Diferent TPS for dose escalation reliably achieved high plan quality. Despite the very good results of HT planning for coverage, conformity, and homogeneity, the TPS also achieved acceptable results for IMRT and VMAT