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The physical and chemical properties of polycyclic aromatic hydrocarbons depend on the size (number of carbon centres) and the topology of the systems. Consequently structure/property relations can be treated as quantitative analogy models with size and topology as the independent variables. This class of compounds is the example par excellence to put forward a general view in chemistry, i.e. topological chemistry. [ABSTRACT FROM AUTHOR]

Types of asbestos are distinguished not only by structure, chemical compositon, shape of aggregates, and length and quality of fibers, but also by its formation. Though consisting of quite common elements, deposits are formed only under very special conditions. Its unique combination of properties has created over 3000 fields of application (about 70% in asbestos cement). Great efforts have been made to substitute all types of asbestos by harmless, similarly cheap and versatile synthetic fibers, owing to the unquestioned carcinogenic properties of all asbestos dusts. However, development of such fibers has not made any remarkable progress until recently. Consequently risk to workers in mining and manufactoring, consumers, outsiders, and the environment should be kept as low as possible by intensifying precautions and diminishing emissions. [ABSTRACT FROM AUTHOR]

A survey is given of properties, formation, and application of muonic atoms in physics, chemistry, and archeometry. In the field of physics the measurement of nuclear charge distributions and vacuum polarization as well as the slowing down of muons in matter are treated in some detail, and in the fields of chemistry and archeometry, non-destructive quantitative chemical analysis of bulk material and, with the help of suitable beam setting, also of selected parts of the specimen. [ABSTRACT FROM AUTHOR]

The degree of purity of surface waters can be seen from investigations on the communities of life of plant and animal organisms. A great number of organisms characteristic of certain degrees of pollution were classified in the 'saprobic system', which is still valid. As a supplement to the chemical water analysis, the bio-ecological test is an optional method for characterizing the quality of waters - as, for instance, in the case of the river Lippe. [ABSTRACT FROM AUTHOR]

The stylistic development of the painted pottery from the excavations of Akrotiri on Thera evidences that the great Late-Minoan eruption of the Thera volcano must be dated around 1500 B.C. The eruption had only minor effects on Crete which were not nearly so serious as has been supposed. The rate of ash fall and the height of the tsunamis did not play a significant role. After the Thera eruption Minoan trade and culture flourished as before. This means that the decline of the Minoan civilization was neither caused nor influenced by this volcanic event as suggested by the Marinatos theory. The Minoan decline was substantially initiated by great devastations in Crete which occurred, according to the ceramic chronology, around 1450 B.C. These destructions were the result of one or several violent regional tectonic earthquake(s) in combination with severe internal revolts. [ABSTRACT FROM AUTHOR]

Copyright of Naturwissenschaften is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)