Verallgemeinerungsfähige Merkmale und Besonderheiten des Sprühkompaktierens

Characteristic Features and Specific Qualifications of the Sprayforming Process to be Generalized The solidification and cooling process of spray formed materials predominates the extent of any segregation and separation process, which is conducive to avoid macro‐segregation and to diminish concentration of alloying components at the grain boundaries. The risk of coarse porosity or of hot cracking is reduced significantly by the momentum of the mass flow during spray deposition. This means that those materials which e.g. during the casting process tend to establish strong segregation effects and cavities and/or hot cracks as well as those which tend to create filaments of carbides, nitrides or sulphides during rolling can be generated by the spray forming process in large dimensions with chemical homogeneity and without any of those defects. A characteristic feature of spray formed materials is the fine equiaxed grain structure and the high ductility. Specific features of this new free forming process will be discussed.     

Erzeugung komplexer botanischer Objekte in der Computergraphik

Zusammenfassung   Der Beitrag besch?ftigt sich mit der Herstellung von 3D-Pflanzenmodellen. Ausgehend von traditionellen Methoden wird ein neues Verfahren vorgestellt, das über regelbasierte Objekterzeugung eine Reihe Modellierprobleme l?st. Insbesondere wird gezeigt, wie hiermit strukturelle und geometrische Komplexit?t beherrscht und integrativ modelliert werden kann. Eingegangen am 02.11.1996, in überarbeiteter Form am 06.06.1997     

Lehre im Bauingenieurwesen – Ganzheitliches,werkstoffübergreifendes Entwerfen und Konstruieren

Eine neue Ausrichtung der akademischen Curricula ist angesichts der heutigen technologischen, ökologischen und gesellschaftlichen Herausforderungen an das Bauingenieurwesen unerlässlich. Der hier beschriebene Ansatz der werkstoffübergreifenden Lehre des Entwerfens und Konstruierens, wie er an der TU Berlin umgesetzt wird, bietet eine Möglichkeit Bauingenieurnachwuchs auszubilden, der sich im konstruktiven Bereich den Herausforderungen der Zeit stellen kann. Teaching Conceptual and Structural Design in a holistic and materialcomprehensive way Due to todays technological, ecological and social challenges a new approach of the academic curricula essential is concerning structural and civil engineering. This paper describes the concept of materialcomprehensive conceptual and structural design as it is taught at the TU Berlin. This is one possibility to educate the next generation of structural engineers, to make them ready for facing the challenges to come.     

Modelling of Protein‐Protein Interactions of Bone Morphogenetic Protein‐2 (BMP‐2) by 3D‐Rapid Prototyping

Recently we were able to apply the technique of 3D‐Rapid Prototyping (3D‐RP) to the construction of highly accurate three‐dimensional plastic models of biomolecules [Laub, M. et al. (2001), Materialwiss. Werkstofftech. 32, 926]. These models are derived from x‐ray crystallographic data and therefore represent exact replicas of the depicted molecules. Due to their accuracy these models should be suitable for the modelling of protein‐protein‐interactions. In a first study using 3D‐Rapid Prototyping models of bone morphogenetic protein‐2 (BMP‐2) we were able to identify a novel structural motive on the concave side of this protein which we termed anthelix since a left‐handed helix (radius ca. 0.8–1 nm, pitch 8–9 nm) can be fitted into this groove. Based on these structural findings we identified a 15mer polypeptide (KNMTPYRSPPPYVPP) from the Brookhaven database as a potential physiological ligand. Molecular docking studies using a geometric recognition approach confirmed the anthelix as a possible binding site for this peptide. However in affinity chromatography experiments no binding between BMP‐2 and the immobilized peptide was observed. As the question arose whether 3D‐Rapid Prototyping is in general suitable for modelling protein‐protein interaction we used dimeric BMP‐2 to study exemplary monomer‐dimer interaction. Molecular docking studies using the monomeric BMP‐2 subunits predicted a structure which is nearly identical to that found in dimeric BMP‐2 (root mean square deviation < 1 Å) proving the suitability of geometric docking. 3D‐RP‐BMP‐2‐monomers (size 140 mm × 75 mm × 65; magnification ca. 22 × 10⁶ fold) constructed from dimeric BMP‐2 could be assembled by hand yielding a structure highly homologous to dimeric BMP‐2. Differences between the 3D‐Rapid Prototyping model of dimeric BMP‐2 and the assembled monomers arose in several gaps at the interface between the two monomers which are not visible in the dimeric structure. These gaps can be explained by the way the solvent‐accessible molecular surface is generated. During this process an exterior probe sphere is rolled over the spherical atoms of the molecule. Distances between the monomers smaller than the diameter of this sphere are bridged thus resulting in a coherent surface. We conclude that 3D‐Rapid Prototyping is in general eligible for the modelling of protein‐protein‐interaction though there are further efforts needed to increase our understanding of this process.