Bullettin of the Gioenia Academy of Natural Sciences of Catania

Arithmetic Rings and their generalizations

R. Strano — Fri, 02 Mar 2018 00:00:00 +0000

Prüfer domains are characterized by various properties regarding ideals and operations between them. In this note we consider six of these properties. The natural generalization of the notion of Prüfer domain to the case of a commutative ring with unit, not necessarily a domain, is the notion of arithmetic ring. We ask if the previous properties characterize arithmetic ring in the case of a general commutative ring with unit. We prove that four of such properties characterize arithmetic rings while the remaining two are weaker and give rise to two different generalizations.

Naturalness and environmental vulnerability in the Nature 2000 sites that cover the ecological corridors of the Calabria’s Ionian side. SIC Foce Neto case study

Fri, 29 Jun 2018 00:00:00 +0000

The Calabria region boasts 179 Sites of Community Interest (SIC) and 6 Special Protection Areas (SPAs). The lack of studies on the state of conservation and environmental quality of these sites (naturalness, artificiality, sensitivity, vulnerability and risk) has led the authors to characterize the 10 SIC that insist on the ecological corridors of the Ionian Calabrian side. Through the Index of Landscape Conservation (ILC) and Environmentally Sensitive Areas Index (ESAi), an Environmental Analysis was conducted aimed at defining, identifying and assessing values and criticalities. Starting from theLand Use Map (CLC), the Map of Naturalness-Artificiality and the Map of Environmental Sensitivity of the aforementioned sites have been created, such as derived maps. This study is concluded with a methodological study on the appropriate methods that should be taken to characterize a SIC thanks to the analysis, made before, on SIC Neto, addressed with phytosociological method.

Chirality from Chemistry to Art and Nature: personal observations

S. Caccamese — Mon, 04 Feb 2019 00:00:00 +0000

Human kind has been in some way aware of chirality for millennia and also Kant in 1783 provided a short description of chirality watching his hand in the looking glass. This observation was about nearly a century before Pasteur established stereochemistry (chemistry in three dimensions of the space) as a new area of science and Van’t Ho and Le Bel proposed the hypothesis of an asymmetric tetrahedral carbon atom. Not only Nature is chiral but to a great extent it exists as just one enantiomer (a mirror image not superimposable upon the original) and, in any case, can tell the dierence between right-handed and left-handed helical structures or objects. A planar structure, suitably designed, become chiral if a torsion angle exists that turns it in a tridimensional structure. Also, a hidden relationship exists between tetrahedron and helix. Biological systems possess a marked chirality sense and biological activities as smell, taste, anti-inflammatory are often related to stereochemical properties. Many examples of asymmetry and helicity can be observed in the plant world as twining vines, flowers in specific families of subtropical plants and common pine-cones. In the animal world the most studied area is the asymmetry of gastropods and snail shells. Helicity in the horns in girgentean goats and in ammonites is an example of meso structures, namely structures where a half part of it is a not superimposable mirror image of the other half part. In works of art several varieties of helical columns, stairs, tridimensional spiral decorations in ancient churches and cloisters try to connect earth with heaven and add magnificence to a façade or an altar. Here I present personal observations through photographs concerning enantiomers in the natural world, art and craftworks.

The “One-hundred horses cave” and the “Cave of the hermit” in the Medium and Lower Alcantara Valley (North eastern Sicily)

Sergio Di Marco, Francesco Falcone — Mon, 04 Feb 2019 00:00:00 +0000

In the territory of San Cataldo, a hamlet of Motta Camastra (ME), near the "Bridge of Mitogio" which joins the two banks of the Alcantara River, there are some lava flow caves, known as "Grotta dei Cento Cavalli" and "Grotta dell’Eremita". The caves, currently little known, were the refuge of famous brigands who marked, even in illegality, important pages of local history of the fifteenth and sixteenth centuries. The oral evidence handed down suggests that the studied caves are part of a more complex system of underground cavities of which they remain the only sign, as one or more cavities were artificially buried by the peasants for unspecified reasons, while others would have been detonated with dynamite to flush out the bandits who were hiding there. From the geological point of view, the study of the two caves brings new important elements in the knowledge of the genesis of the lavas that emerge in the middle and lower Alcantara Valley, as the study of the morphometry of the cavities and of the spatial articulation of the same, as well as other considerations on the geomorphological evolution of the places, it was possible to identify the eruptive center that generated them a few tens of meters to the north-east. This work adds an important piece to understand the volcanological mechanisms that allowed the emergence of eusive activities in an area so peripheral to the Etna volcanic edifice, and implement what recently published by one of the authors (Di Marco Sergio, 2016), which had already identified about two kilometers further upstream, in the locality "Gole dell’Alcantara"(The Gorges of Alcantara), another lava emission center. The identification of another eruptive center, allows to frame the eruptive fissure of the Alcantara Gorges no longer as a "punctual" event of peripheral Etna volcanism, but allows to delineate a more complex system of tectonic dislocations structured within the fluvial valley, and used by deep magmas as a way of ascending to the surface. In this work was privileged the descriptive part of the caves, in order to better distinguish the data collected in the field with the hypotheses that derive from it. We refer to a following work for a more organic description of the geology of the sites and of the volcanological and tectonic-structural factors justifying eusive events in such a peripheral area and beyond the northern limit of the Etna volcano edifice.