Inhomogene Minima von Sternkörpern

Ohne Zusammenfassung     

Prime ideals and radicals of centred extensions and tensor products

In this paper, we study prime ideals and radicals of centred extensions of rings. Obtained results are applied to tensor products of algebras over commutative rings. This research was partially supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil. The second-named author was also supported by KBN grant 2 P301 035 06.     

Excitonspektren von Silberhalogeniden und ihren Mischungen

The absorption spectra of AgBr and AgCl as well as their mixtures were investigated at liquid oxygen temperature. There are two characteristical features for exciton bands: the terms of the free atoms, and the structure of the crystal lattice. For pure and mixed crystals there exist doublets which can be derived from the terms of the free halide atoms. The wavelengths of the exciton bands shift linearly with increasing content of AgCl in AgBr. For the first band of the absorption edge this shift is 70 cm^?1 per mole percent admixture. The bands shift to a greater extent than they broaden. Thus from statistical calculations can be deduced that there is a region of about 125 anions responsible for an absorption act. The exciton bands depend considerably on thermal influences from the lattice as well as on distortions resulting from ultraviolet exposure.     

Homogene Lösungskatalyse. Über die milieubedingte hemmende und aktivierende peroxidatische Wirkung von Zn2+−, Cr3+− und CrO −lonen in homogener Lösung

The title ions are in sodium acetate solution activators, and in sodium tartrate solution inhibitors, for the peroxidatic decolouration of indigocarmine by H₂O₂ at 37 °C.     

Quantitative measurements on wetted thin layer chromatography plates using a charge coupled device camera

This paper presents the first study of imaging of spots on thin-layer chromatographic plates whilst still wet with solvent. Imaging and quantification of Sudan II after development with dichloromethane was carried out in both reflectance and transmission modes, using a charge coupled device (CCD) camera. The relationship between peak area and sample loading was established at low sample loading, and found to be linear over an order of magnitude for both wet and dry modes with r2-values > 0.99. All data processing was carried out using the Beer-Lambert equation. Curvature at high loadings in the plots of integrated absorbance as a function of sample loading was accounted for using an empirical expression designed for use with the Kubelka-Munk treatment and apparent absorbance of the stationary phase due to scattering. Results are consistent with an effective pathlength significantly longer than the thickness of the sorbent layer. The limit of detection on a dry plate (0.5 ng) was found to be lower than on a wetted plate (2 ng). Precision was found to be 1-4% RSD intra-plate and 8-14% RSD inter-plate. Results are compared with quantification of the same analyte on dried plates.