Über ein Lemma der komplexen Approximationstheorie

We prove an essentially extended version of Nersesjan's Lemma about rational approximation of certain 0,1-valued functions. Our proof makes no use of integrals but is based on properties of conformal maps as well as on results about cluster sets and on plane-topological considerations.     

A contrast variation of image speckle intensity under illumination of partially coherent light

Speckle patterns are formed by completely and partially coherent light at the image plane of a diffusing object. The general formula is derived for the contrast variation of the image speckle intensity distribution as a function of the spatial coherence of the illuminating light, the amplitude point-spread function of the optical imaging system and the statistical characteristic of the diffusing object. The effect of spatial coherence of the illuminating light on the contrast variations of the image speckle intensity distribution is theoretically evaluated under various statistical conditions of the diffusing object. The theoretical results are confirmed experimentally.     

Reactions leading to the formation of O-3 on magnesium oxide

Ozonide ions were observed on MgO upon irradiation (254 nm) in the presence of O₂ at 25°C or upon reaction of O^-₂ on the surface with N₂O at 100°C. In the former case on O^-₂ intermediate is photodissociated to O and O^-. The latter subsequently reacts with O₂ forming O^-₃.     

Self-pulsing at an oil/water interface in the presence of phospholipid

Irregular electrical potential oscillations and interfacial tension were observed in an oil/water system consisting of nitrobenzene and an aqueous solution of 5 vol% butanol. When phospholipid, dipalmitoylphosphatidylethanolamine (DPPE), was added to the aqueous phase in this system, rhythmic oscillations were generated. The molecular mechanism for the oscillations has been interpreted with the aid of computer simulation based on a set of nonlinear differential rate-equations.     

Ionic dissociation of ionene polymers in aqueous solutions

The degree of ionic dissociation of aliphatic ionene polymers, 3,3-, 4,4-, 6,6-, and 8,8-ionene bromide in salt-free aqueous solutions at infinite dilution was obtained by emf measurements with a bromide ion electrode. The results show that the longer the methylene chain between neighboring charges on the polymer backbone, the greater is the degree of dissociation, as Manning's theory predicts. The distance between the neighboring charges on the polymer backbone was calculated by using Manning's equation. The distance was compared with that calculated geometrically on the basis of the contour length of the molecule according to Manning's definition. The former distance was much smaller than the latter. The former distance was then compared with the length calculated from Eyring's equation for the end-to-end distance of a freely rotating methylene chain. In this case, good agreement was obtained.