In search of the plastic enzyme

Photozymes are novel polyelectrolytes made from mixtures of hydrophobic and hydrophilic comonomers. They often contain a relatively high concentration of bound chromophores as photon harvesting or antenna groups, which transport excitation energy to organic substrates located in the interior of the macromolecular coil in aqueous solution. Previous studies have shown that the photocatalytic behavior of these polymers has many similarities to natural enzymes which carry out thermal reactions in biological systems. Mechanistic studies of four photozyme reactions are discussed: (1) the oxidation of perylene to perylenequinones; (2) the dehalogenation of hexachloro- and pentachlorobenzene; (3) the high-yield synthesis of Vitamin D; and (4) the selective photolysis of aliphatic and aromatic ketones.     

Implementation of Thermomechanical Coupling for Shape Memory Alloys into the Finite Element Method

NiTi alloys open up new fields of application on the basis of their distinctive thermomechanical properties. Many options of practical application of shape memory alloys are imaginable. For example catheters or stents made of NiTi play an important role in medical technology. Thus the further development and optimisation of simulation tools for shape memory alloys (SMA) structures will play an important role in the future. Based on the powerful material model of Helm [1] the present contribution focuses on the coupling between mechanical and thermal fields. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solid-Shell Finite Elements for Tesselated Geometries

Sandwich structures made of sheets of composite materials are in widespread use, particularly in the transportation industry. Finite Element simulation of the thin, tesselated structures with complex, three-dimensional material behaviour is a challenging task for the underlying element technology. In particular, frequently used linear isoparametric approaches exhibit unphysical stiffening phenomena. Recent developments in solid-shell finite element technology aim to overcome these undesirable effects. Here, they are applied to an example of a corrugated sandwich core under transversal compression. A study of convergence is conducted with respect to commercially available shell and solid finite elements, and their ability to reproduce the bending dominated deformation state. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)