Large-scale electric fields and currents and related geomagnetic variations in the quiet plasmasphere

At the end of the sixties it became obvious that two-dimensional dynamo models can explain nearly all facts, which had been found morphologically for mean annual Sq-fields. During the recent decade new or improved methods to measure electric fields (e.g. incoherent scatter facilities) and to investigate great data files have been developed. New informations received with these methods about the existence of regular variations of the Sq-field in dependence on season and universal time and about the electric field have been summarized in Section 2. All attempts to describe also these variations with a two-dimensional dynamo model did not lead to any success, but showed a strong theoretical over-estimation of the asymmetries. Therefore, it must be concluded that three-dimensional plasmaspheric current systems, taking into consideration the coupling between both hemispheres along the high-conducting magnetic field lines, are needed in order to explain the regular variations of the Sq -field. The basic equations for two- and three-dimensional dynamo models, different methods for the solution of these equations and the resulting models from different authors are compiled and discussed (Section 3).Based on all morphological and theoretical results a plasmaspheric-ionospheric current system has been constructed and some properties of the plasmaspheric field-aligned current distribution, have been derived.     

Effect of temperature on the adsorption of adenine

Equilibrium adsorption isotherms for the purine base adenine on the surface of graphite crystals have been obtained at 30, 40, 50, and 60 degrees C by frontal analysis using water as a mobile phase. These data were fitted to the Langmuir isotherm model and interpreted in terms of the well-characterized adsorbate monolayer structure. A van't Hoff plot was used to estimate the adsorption enthalpy, -delta H degree which we determined to be 20 kJ mol-1. The susceptibility of nucleic acid bases to aqueous-phase hydrolysis may have been a limiting feature for their inclusion in the primordial genetic architecture; our results suggest that the effects of temperature and the presence of inorganic solids must also be included when assessing the prebiotic availability of adenine.