Building stone employed in the historical monuments of Eastern Sicily (Italy). An example: the ancient city centre of Catania

An archaeometric study of the stone materials employed in the Late Baroque historical monuments of the ancient city centre of Catania was carried out. Lithological maps of a selection of monuments, transferred to a digital format, revealed that the stone materials are both magmatic and sedimentary rocks, the colours of which are matched in a peculiar type of bichromy. Particular attention focused on sedimentary rocks, which consist of various types of limestone quarried near the city of Syracuse (Hyblean Plateau, south-eastern Sicily). Carbonate rocks were characterised in terms of mineralogy, petrography and geochemistry, by studying rock samples from both monuments and historical extraction sites. Results showed that, although only one name was historically attributed to the above lithotypes (i.e. “Pietra di Siracusa‘’), they were quarried from many locations and, as they belong to various geological formations, they therefore exhibit great variety. In order to examine the durability of Hyblean limestones employed in works of cultural heritage interest, salt crystallisation tests were carried out according to standard procedure norms (UNI EN 12370 (1999) Determination of resistance to crystallisation of salts, 6p). Results are consistent with the forms of deterioration observed in the monuments, and highlight the close relationship between textural characteristics and damage. Our purpose is to provide a basic tool, which may be useful both for conserving monuments of cultural heritage and for their restoration.     

Strategies to Make Methods Based on Flow Injection Analysis Greener

The implementation of flow injection analysis (FIA) systems and correlated techniques in the laboratory routine provides an increase of analytical throughput and the reduction of risks of analyte losses and contamination. Naturally, it contributes to the reduction of reagent consumption and minimization of waste generation. This paper presents and discusses an overview of the main strategies adopted to make methods based on FIA systems more environmentally friendly, and offers a review of these methods that covers the period from January 2002 to December 2019. Strategies based on reagent management (adoption of procedures without reagents, replacement of toxic reagents, recycling and reuse of reagents and, use of immobilized reagents), the online waste treatment, and the improvements of FIA systems (flow system configurations that avoid reagent wastage, use of green detectors, automation, and miniaturization) are approached in this perspective.     

Geographical ecology of the symbiotic crabs Libinia ferreirae and Libinia spinosa: Distributional patterns in south and south-eastern coast of Brazil

The Brazilian coast is home to two species of Majoid crabs: Libinia ferreirae and Libinia spinosa, with similar habits, as they live in symbiosis with the jellyfish Lychnorhiza lucerna during their juvenile stage and dwell on the bottom of the ocean near the coast when adults. This study investigated the spatial and temporal distribution of L. ferreirae and L. spinosa during different ontogenic phases on the south and south-eastern coast of Brazil, between latitudes 22º and 27ºS. Our results showed that both species have different distributions during their development in the three studied regions. Libinia ferreirae were more abundant associated with jellyfish, and L. spinosa were more abundant in the free-living phase. Environmental factors, especially temperature and salinity, for associated and free-living crabs, respectively, are the main factors that need to be supported for the establishment of these specimens. We were able to identify that the presence or absence of hosts (given the ecological interactions between the species) is determinant in finding the associated crabs. Geographical variations (morphology of the regions, marine currents and the strength of the tide) are linked directly to the movement of the jellyfish hosts to the coast, influencing the abundance of L. fereirae and L. spinosa populations and affecting their distribution patterns. We can infer that both species are connected with other populations because of the association with the jellyfish, crabs could be passively transported along the south and south-eastern coast of Brazil, maintaining the connection between metapopulations.     

Multi-frame and multi-dimensional historical digital cities: the Como example

In this article, we present the realisation of a multi-frame and multi-dimensional WebGIS that allows users to simultaneously analyse a specific portion of the Earth taking into account the historical information, too. Two graphical panels have been realised: one for the usual 2D view and one for a more realistic 3D view. Both panels display historical maps of the city, the current orthophoto and the digital topographical map. The 3D frame is based on NASA World Wind, an open source virtual globe from where 3D buildings are shown extruding the 2D shapes using their mean height. Thanks to a specifically designed graphical user interface, it is also possible to dynamically thematise the buildings on the globe according to different criteria (e.g. the construction time span) so that only the geometries fulfilling the request are turned on. Within the proposed application, a synchronisation between the two panels has been implemented, in order to maintain a constant alignment of the two viewers. The application is also open to the time dimension. In fact, assigning to each geometry two dates (e.g. ‘year of construction’ and ‘year of demolition’), it is possible to dynamically view how buildings have changed over time, both in their shape and height. Future developments of this work will concern the possibility of implementing a city model with a higher level of detail.     

Revised photometric elements of three semi-detached binary systems

TheV andB light curves of three Algol-type eclipsing binaries (UZ Cyg, VW Cyg, AQ Peg), observed by Ammanet al. (1979), have been analysed using the Wilson and Devinney (1971) model. We find that all of them are semi-detached systems, with A-type primary components and K-type evolved secondary which fill the corresponding lobe, although VW Cyg should perhaps be considered as an sd-d system.     

The almost contact system RU Eridani

TheV andB light curves of the eclipsing binary RU Eridani, published by Sarma and Sanwal (1981), have been analysed by means of the Wilson and Devinney (1971) method, in order to obtain a solution based on the Roche model, as distinct from the Russell and Merrill model, used by Sarma and Sanwal. The system turns out to consist of an evolved K1 secondary which appears to fill the lobe, capable of containing its mass, and of an F0 V primary, which seems almost to fill its own. An estimate of the absolute elements of RU Eri has been made, on the assumption that the primary has a mass corresponding to its spectral type according to Allen (1973).     

Effectiveness of time-series analysis for thermal plume propagation assessment in an open-loop groundwater heat pump plant

Thermal perturbation produced in the subsurface by open-loop groundwater heat pumps (GWHPs) represents a complex transport phenomenon that is affected by several factors, including intrinsic characteristics of the exploited aquifer, abstraction and reinjection well features, and the temporal dynamics of the accessed groundwater. Post-GWHP water may have become warmed or cooled before being reinjected into the aquifer, thereby creating a thermal plume, known as the thermal affected zone (TAZ), which can alter aquifer temperature. The TAZ is propagated mainly by advection, after which the plume tends to degrade via conductive heat transport and convection within moving water. Groundwater monitoring and multiparametric probes are used to check the dynamics of plume propagation and whether a system’s thermal plumes are generating unsuitable interference with wells, subsurface infrastructure, or land use. Analyses of time-series groundwater monitoring data can be used to monitor TAZ movement. In this paper, the thermal plume velocity was calculated by both an analytical solution and cross-correlation. Cross-correlation calculated between temperature measured in the reinjection well and control downstream piezometers can reveal plume dynamics and demonstrate the importance of advective transport in aquifer heat transfer.