Review and enhancement of 3D concrete models for large‐scale numerical simulations of concrete structures

The present paper focuses on selected plasticity and damage‐plasticity models for describing the 3D material behavior of concrete. In particular, a plasticity model and a damage‐plasticity model are reviewed and evaluated. Based on the results of the evaluation, enhancements are proposed, aiming at improving the correspondence between predicted and observed material behavior and aiming at implementing a robust and efficient stress update algorithm in a finite element program for performing large‐scale 3D numerical simulations of concrete structures. The capabilities of the concrete models are demonstrated by 3D numerical simulations of benchmark tests with combined bending and torsional loading and combined compression and shear loading and by a large‐scale 3D finite element analysis of a model test of a concrete arch dam. Copyright © 2011 John Wiley & Sons, Ltd.     

The meteoritic origin of Tutankhamun's iron dagger blade

Scholars have long discussed the introduction and spread of iron metallurgy in different civilizations. The sporadic use of iron has been reported in the Eastern Mediterranean area from the late Neolithic period to the Bronze Age. Despite the rare existence of smelted iron, it is generally assumed that early iron objects were produced from meteoritic iron. Nevertheless, the methods of working the metal, its use, and diffusion are contentious issues compromised by lack of detailed analysis. Since its discovery in 1925, the meteoritic origin of the iron dagger blade from the sarcophagus of the ancient Egyptian King Tutankhamun (14th C. BCE) has been the subject of debate and previous analyses yielded controversial results. We show that the composition of the blade (Fe plus 10.8 wt% Ni and 0.58 wt% Co), accurately determined through portable x‐ray fluorescence spectrometry, strongly supports its meteoritic origin. In agreement with recent results of metallographic analysis of ancient iron artifacts from Gerzeh, our study confirms that ancient Egyptians attributed great value to meteoritic iron for the production of precious objects. Moreover, the high manufacturing quality of Tutankhamun's dagger blade, in comparison with other simple‐shaped meteoritic iron artifacts, suggests a significant mastery of ironworking in Tutankhamun's time.     

Short time-scale impacts of hydropeaking on benthic invertebrates in an Alpine stream (Trentino,Italy)

The impact of a single hydropeaking event was studied in the Alpine stream Noce Bianco. Four stations were selected, one upstream and three, respectively, at 0.25, 6, and 8 km downstream from a hydropower plant. We collected drifting invertebrates during a planned water release that increased the discharge 7-fold. At the onset of the hydropeaking wave the number of invertebrates lost from the riverbed per minute to the drift increased 9-fold at the first downstream station and the same effects propagated 8 km downstream. The drift was composed mainly of aquatic insect larvae (Chironomidae, Plecoptera, Ephemeroptera Baetidae, and Psychodidae, with Chironomidae as the most abundant taxon at all stations) and partly by larval and adult riparian insects, and by Oligochaeta, which were particularly abundant at the station 6 km downstream. We monitored drift for 30 min from the start of the water release: peaks in drifting invertebrates occurred within 5–10 min of the beginning of the hydropeaking wave, and most of the invertebrates were washed out within the first 15 min of the water release. The different timeframes were possibly due to habitat preferences (most of the taxa that increased in the drift at the arrival of the wave were associated with algae and organic debris, which were washed off quickly by the increase in discharge) and/or behavioral adaptations (other taxa initially resisted the shear stress and began to drift with a delay of 5–10 min). The temporal pattern and drift composition corresponded well with those reported in literature, and indicate that repeated high-flow events of similar magnitude cause considerable losses from benthic populations to drift.     

Cytochrome P4501A expression,chemical contaminants and histopathology in roach,goby and sturgeon and chemical contaminants in sediments from the Caspian Sea,Lake Balkhash and the Ily River Delta,Kazakhstan

Roach, goby and sturgeon were examined for cytochrome P4501A (CYP1A) expression and histopathology, in relation to contaminant burdens in fish and sediment. Gradients of induction of CYP1A were observed. Roach from the Ural and Ily River Deltas and roach and goby from the two stations nearest the Caspian Sea oil fields displayed higher levels of CYP1A expression in several organs than was observed in fish from further offshore. Great sturgeon and Russian sturgeon showed higher levels of CYP1A expression than was seen in starred sturgeon and gobies in the Ural delta. No fish showed evidence of contaminant-related histopathologies in the organs examined, despite the elevated CYP1A levels. Low levels of polychlorinated biphenyls and elevated levels of inshore and riverine petroleum hydrocarbons from these habitats suggest that this ongoing hydrocarbon exposure, and that from natural sources and long-term oil exploration on the Northeastern Caspian shore, contributed to the CYP1A induction observed.     

Strange attractors in plagioclase oscillatory zoning: petrological implications

Oscillatory zoning in plagioclase crystals from different mixed lava flows cropping out on the Island of Capraia (Italy) has been investigated. An-calibrated profiles from back-scattered-electron images are used as compositional time series of oscillatory zoning. They are analyzed by a qualitative visual method that allows to appreciate at first sight the global structure of the time series and by a quantitative method to reconstruct the attractors associated to the oscillatory patterns, and to calculate the fractal dimension of attractors. Results show that attractors have fractional dimensions, indicating that series are chaotic. In addition, it is evidenced that there is a wide variation in oscillatory zoning in crystals from the same lava flow and that plagioclase populations from the different lava flows differ in the shape of frequency histograms of attractor dimension. The development of oscillatory zoning is simulated by considering a chemically inhomogeneous magmatic mass governed by chaotic flow fields, coupled with chemical diffusion, in which plagioclase crystals grow according to the availability of nutrients in their neighborhoods. Results show that in such a dynamical system plagioclase crystals develop chaotic zoning patterns analogous to those observed in natural plagioclases. This approach allows us to explain the differences observed in plagioclase crystals from the same lava flow and the differences in the shape of frequency histograms of attractor dimensions in the four lava flows.     

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.     

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.