The high-resolution time-of-flight spectrometer TOFTOF

The TOFTOF spectrometer is a multi-disc chopper time-of-flight spectrometer for cold neutrons at the research neutron source Heinz Maier-Leibnitz (FRM II). After five reactor cycles of routine operation the characteristics of the instrument are reported in this article. The spectrometer features an excellent signal to background ratio due to its remote position in the neutron guide hall, an elaborated shielding concept and an s-shaped curved primary neutron guide which acts i.a. as a neutron velocity filter. The spectrometer is fed with neutrons from the undermoderated cold neutron source of the FRM II leading to a total neutron flux of 10¹⁰n/cm²/s in the continuous white beam at the sample position distributed over a continuous and particularly broad wavelength spectrum. A high energy resolution is achieved by the use of high speed chopper discs made of carbon-fiber-reinforced plastic. In the combination of intensity, resolution and signal to background ratio the spectrometer offers new scientific prospects in the fields of inelastic and quasielastic neutron scattering.     

Analysis of grain boundary movement analogous to dislocation movement – both with a matrix having precipitates

In the present investigation it has been shown exemplarily for an austenite microstructure containing carbonitrides that the specific restraining force of a grain boundary due to the distribution of precipitates can be described by a modified Orowan's law, so that the grain boundary movement is considered to be analogous to the dislocation movement. This is achieved by using a modified restraining force F_r (corresponding to the cubic geometry of the particles), a detailed thermodynamic analysis of the precipitates (in this case, carbonitrides) and selected relation for the interparticle spacing L_a. The specific restraining force and the interparticle spacing depend on temperature within the austenite range. Each temperature is attached to a couple (F_r/L_a). The plot F_r against shows straight lines for each steel and from their average slope, a shear module G' of grain boundaries, which is about 64300 N·cm^?2, is obtained. Hence, it is possible to describe the specific restraining force of a grain boundary with the help of Orowan's law or as it is conventionally done by using Zener's modell. At a critical temperature T*, which is different for each steel, the specific restraining force is equal to the driving force of the grain boundary. The corresponding values of L_a are also different for each steel and the steel which is the most resistant to grain coarsening is allowed to have the greatest value of L_a which still retains the capacity of impeding grain coarsening.     

Die Relevanz einer institutionalisierten Ethik für eine professionelle Zahnmedizin

Definition of the problem

The concept of “ethics” has recently been incorporated into both the 2014 Model Professional Code for Dentists and the current version of the “National Competence-Based Catalog of Learning Objectives in Dental Medicine” (NKLZ, Nationaler Kompetenzbasierter Lernzielkatalog Zahnmedizin). The study presented here addresses the question which relevance this has for the relevance of the new concept accomplished for the dental profession and society.

Arguments

To this end, the societal processes that are related to the autonomous freedom of action of the dental profession are discussed. Therefore the sociological fields of discourse such as profession (and the effect of its constitutive antinomies), trust, education, expertise, practice of treatments and sanction are reviewed for their potential of having connections to each other and serving as a structural frame concerning an ethically reflected acting of the professional. The basis of the professional freedom of action is the trust of society and the individual patient in the professionally acting dentist.

Conclusion

The study arrives at the conclusion that it was a serious omission for many decades not to make young dentists aware of the ethical foundations of dental activity on an institutionally established basis and thus failing to encourage them to constantly reflect their professional expertise in relation to the problems to be solved. This deficit has now been identified. It is absolutely essential to implement an institutionalized structure dealing with ethical questions within the scope of dental medicine.

     

Spatial distributions of O2, CO2 and SO2 in a pilot-scale fluidized bed combustor operated with different coals

Axial concentration profiles of O₂, CO₂ and SO₂ have been measured at different radial positions in a coal-fired fluidized bed combustor. The profiles show some spatial inhomogeneity in the bed, the degree of which depends on fluidizing velocity and amount of excess air. Comparison of SO₂- with CO₂-concentration profiles reveals that SO₂ is formed in proportion to CO₂ only with anthracite as fuel. With bituminous coals, SO₂ is preferentially formed near the coal feed point. These results are discussed with regard to characteristic times of mixing and chemical reaction in fluidized beds, and SO₂-formation characteristics of the employed coals obtained in a thermobalance.     

Kontextbasierte Kooperation für mobile Geschäftsanwendungen

Realistic requirements of mobile business applications often exceed the capabilities of their respective local environments. In order to overcome such restrictions of specific mobile devices, services, and resources, this contribution introduces the concept of context-based cooperation. It is based on mobile processes which enable applications to cross boundaries of individual systems and thereby allow combining both mobile and stationary resources in order to realize highly dynamic individual applications. This contribution presents an approach for realizing context-based cooperation built upon on a respective context management infrastructure and execution environment. It also identifies specific requirements and proposes related enhancements for mobile business applications.     

Festigkeitsänderungen bei verschiedenen Verformungsarten

Bestimmung von Streckgrenze und Zugfestigkeit beim Ziehen und Walzen von Stahldrähten mit Kohlenstoffgehalten zwischen 0,006 und 0,6%. Einfluß des Wechsels der Verformungsart vom Ziehen zum Walzen auf den weiteren Anstieg der Festigkeitswerte. Anfänglicher Abfall der Festigkeitswerte vor allem bei patentierten Stahldrähten mit höherem Kohlenstoffgehalt. Deutung des Festigkeitsabfalles als Zerstörung der bei der Verformung aufgetretenen Alterung und Änderung der gerichteten Eigenspannungen zwischen den verschiedenen Phasen.     

Praxisorientierte Raffination von Stahlschmelzen mit Seltenerdmetallen

Simulation eines pfannenmetallurgischen Stahlraffinationsverfahrens unter Verwendung von Cer-Mischmetall, einer Raffinationsschlacke und Argonspülung zur Reinheitsgradverbesserung. Darstellung typischer nichtmetallischer Einschlüsse. Aufzeigen der erzielten Zähigkeitsverbesserungen und der Verringerung der Zähigkeitsanisotropie.     

Ermittlung von gelöstem Kohlenstoff und Stickstoff mit einem Torsionspendel für streifenförmige Proben

Beschreibung eines Torsionspendels zur Messung der Dämpfung und Ermittlung des Gehaltes an gelöstem Kohlenstoff und Stickstoff an streifenförmigen Proben mit niedrigen Gehalten an interstitiell gelösten Elementen. Messung der Dämpfung bei Eisen-Kohlenstoff-, Eisen-Stickstoff- und Eisen-Kohlenstoff-Stickstoff-Legierungen ohne und mit Mangan. Darstellung der rechnerischen Ermittlung von Kohlenstoff und Stickstoff bei gleichzeitigem Vorliegen beider Elemente.