In-situ FTIR spectro-electrochemistry of polyaniline

The structure and the electrochemical oxidation reactions of polyaniline in an organic electrolyte are studied usingin-situ FTIR spectroscopy. In the first oxidation process a decrease of the N-H absorption band is observed, indicating a loss of hydrogen atoms. In the second oxidation step anion intercalation occurs. A broad absorption band at 4000 cm^–1 is assigned to free carrier transitions in the conducting form of polyaniline.     

On the automorphisms of normal subgroups of the collineation group of affine spaces

We show that the automorphisms of some normal subgroups of the full collineation group of finite dimensional affine spaces are induced by inner automorphisms of the collineation group.Dedicated to Helmut Karzel on the occasion of his 60^th birthday     

Point-Reflection Geometries, Geometric K-Loops and Unitary Geometries

There are reflection geometries to which correspond K- loops (P,+,F) with an incidence fibration F (= incidence partition), where F consists of proper subloops which are not groups. Such examples are derived from certain unitary geometries.     

Cooperative effects in restricted rotations of aryl groups in 2,4,6,8-tetraary-3,7-diazabicyclo[3.3.1]nonanes and related systems

The free energies, enthalpies and entropies of activation for the rotation of the aryl groups in the N,N′-dimethyl and N,N′-dichloro derivatives of rel-(2R,4S,6S,8R)-2,4,6,8-tetrakisaryl-3,7-diazabicyclo[3.3.1]nonanes have been determined and compared with related tricyclic systems which cannot undergo chair-to-boat conformational changes. It is concluded on the basis of the large, negative value of ΔS³ for rotation of the 2(4) aryl group that this rotational process is correlated with rotation of the 8(6) aryl group. The 8(6) aryl group can however rotate independently of the 2(4)-aryl group. The usefulness of the entropies of activation as a criterion for cooperative rotation of groups is briefly discussed.     

Size Separation of Particles from Aerosol Samples using Impactors and Cyclones

Investigations are presented on particle separation in impactors, sampling cyclones and other precollectors. These devices are increasingly used for the characterization of particulate matter. Size selective samplers must be characterized by their grade efficiency curves. A new measuring procedure is presented, which permits the determination of the grade efficiency curves of various sampling devices. An optical particle counter and a vibrating orifice generator are used in these measurements. This calibration technique is fast and has a high resolution. Investigations were carried out on the influence of various parameters on the classification efficiency of impactors and sampling cyclones. Using the extensive data measured a better understanding and quantification of impactor and cyclone behaviour is developed which may improve their applications in particle sampling.