Ueber Indicatoren zur Alkalimetrie und Acidimetrie

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Ueber die Bestimmung der Moleculargewichte von Gasen

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C1‐Linked Spirobifluorene Dimers: Pure Hydrocarbon Hosts for High‐Performance Blue Phosphorescent OLEDs

Reported here are C1‐linked spiro‐bifluorene dimers. A comprehensive study is carried out to analyze the electronic properties of these highly twisted structures. This work shows that the C1‐position enables the design of pure hydrocarbon materials, with a high triplet energy, for hosting blue phosphors in efficient phosphorescent OLEDs (PhOLEDs). To date, this work describes the highest performance of blue PhOLEDs ever reported for pure hydrocarbons (external quantum efficiency of ca. 23 %), thus highlighting the potential of the C1‐spirobifluorene scaffold in organic electronics.     

Control of transient chaos in tent maps near crisis. II. Periodic orbit targeting

Recent work on a symbolic approach to the calculation of probability distributions arising in the application of the Ott-Grebogi-Yorke strategy to transiently chaotic tent maps is extended to the case of control to a nontrivial periodic orbit. Closed forms are derived for the probability of control being achieved and the average number of iterations to control when it occurs. Both single-component and multiple-component targeting are considered, and illustrative examples of the results obtained are presented.     

Examples of attracting sets of birkhoff type

We discuss an explicit example of a map of the plane R ² with a nontrivial attracting set. In particular, we are concerned with the concept of rotation number introduced by Poincaré for maps of the circle and its subsequent extension by Birkhoff to maps of the annulus. The use of rotation number allows nontrivial attractors to be distinguished. The map we discuss has an attracting set containing a set of orbits with infinitely many different rotation numbers. We obtain the map by considering an Euler iteration of a family of vector fields originally described by Arnold and find that the resulting Euler map undergoes some bifurcations which are analogous to those of the family of vector fields. Specifically, there are Hopf bifurcations where changes of stability of a fixed point result in the creation of an attracting circle. The circle which grows from the fixed point is then shown to undergo structural changes giving nontrivial attracting sets. This arises from Euler map behaviour for which the corresponding vector field behaviour is a heteroclinic saddle connection. It is possible to give an explicit trapping region for the Euler map which contains the attracting set and to describe some of its properties. Finally, an analogy is drawn with attracting sets which arise for forced oscillators.     

Anwendung von Fermenten bei der Untersuchung von Pflanzen

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