ABSTRACT
The paper presents novel parameters which can be used for a swift characterization of all kinds of liquid foams. The procedure of the automated method developed consists of introducing a predefined volume of gas into the test solution contained in a cylindrical glass column at constant flow rate. The levels of the foam and of the solution are recorded simultaneously in dependence on time using a photosensor system. Two novel parameters, called time of deviation and time of transition, have been derived on the basis of simultaneous measurements of the changes in the foam volume (DeltaV(F)) and the corresponding volume of the drained solution (DeltaV(S)). These parameters enable one to distinguish three different stages of the foam decay, and on their basis the foam stability can be predicted, irrespective of whether constituting an unstable (wet) or a (meta)stable (dry) foam system. The validity of the method elaborated is demonstrated by applying various unstable and stable foam systems, including biological surfactants such as sugar and lung surfactants.
ABSTRACT
Polycyclic aromatic hydrocarbons (PAH) have become an ubiquitous upper soil component in consequence of industrialisation involving a multitude of combustion processes. Meaningful contaminations can be found on child playgrounds, for example. These may enter into the organism of small children playing there, as children are capable of unintentionally swallowing minute quantities of foreign matter - be that as it may, we cannot exclude such a possibility. Suitable rules are mandatory in particular to prevent such occurrences in an area that is susceptible to them, as preventive health care should always be the order of the day. In the following article we report on the present scientific-toxicological state of the art, on update data on environmental pollution and reasons for a quantitative risk assessment for different paths of pollution.
