Model for the formation of a microscopic Turing structure: The facetting of Pt(110) during catalytic oxidation of CO

A Monte Carlo simulation of the formation of regular facet patterns during catalytic CO oxidation on Pt(110) has been conducted. The simulation was based on the elementary steps of the surface reaction, the CO-induced 1×1⇄1×2 phase transition, and the enhancement of O2 adsorption at step sites. The model can reproduce the formation of sawtoothlike facet patterns with a spacing of ∼100 to 200 Å. The facets represent a Turing structure caused by the coupling of kinetic instabilities with the mass transport of Pt atoms

Formation of Turing structures in catalytic surface reactions: The facetting of Pt(110) in CO+O₂

The Pt(110) surface facets during the catalytic oxidation of CO, if reaction conditions are adjusted such that the CO‐induced 1×1⇄1×2 phase transition can take place simultaneously. A detailed low‐energy electron diffraction beam profile analysis revealed that regularly spaced (430) and (340) facets are formed with a lateral periodicity of ∼70 lattice units along the [11̄0] direction. This result, together with the observation that the facetted surface is only stable under reaction conditions, indicates a dissipative structure of the Turing type. Such structures, which are stationary but exhibit a periodic variation of the concentration variables in space, have so far almost exclusively been discussed theoretically. The interpretation of the facetted surface as a Turing structure could be confirmed by a Monte Carlo simulation based on the Langmuir Hinshelwood mechanism of catalytic CO oxidation and the CO‐induced 1×1⇄1×2 phase transition

Risikofaktoren krimineller Rückfälligkeit

Es wird untersucht, in wieweit die Faktoren Häufigkeit der Unterbringung, Alter bei erstunterbringung, Gesamtunterbringungszeit und eine Kombination aus diesen Faktoren geeignet sind zur Vorhersage von Rückfälligkeit

Kontrolle der Gewalt – Ein Blick auf das Konzept der Kontrolle

Haupt H-G, Heitmeyer W, Kaletta B, Kirschner A. Control of violence - a view on the concept of control. ZiF-Mitteilungen. 2008;2008(3):4-13

Dielectrophoretic immobilisation of antibodies on microelectrode arrays

A silicon based chip device with a regular array of more than 100 000 cylindrical sub-microelectrodes has been developed for the dielectrophoretic (DEP) manipulation of nanoparticles and molecules in solution. It was fabricated by a standard CMOS (complementary metal oxide semiconductor) compatible process. The distribution of the electrical field gradient was calculated to predict the applicability of the setup. Heating due to field application was determined microscopically using a temperature sensitive fluorescent dye. Depending on voltage and frequency, temperature increase was found to be compatible with protein function. Successful field controlled immobilisation of biomolecules from solution was demonstrated with the autofluorescent protein R-phycoerythrin (RPE) and with fluorescently labelled IgG antibodies. Biological activity after DEP application was proven by immobilisation of an anti-RPE antibody and subsequent binding of RPE. These results demonstrate that the developed chip system allows the directed immobilisation of proteins onto microelectrodes by dielectrophoresis without the need for any chemical modification and that protein function is preserved. Being based on standard lithographical methods, further miniaturisation and on-chip integration of electronics towards a multiparameter single cell analysis system appear near at hand