Defect tolerance in soft materials

Abstract The ability of materials to withstand defects like cracks, notches or generic geometric discontinuities, is usually indicated as flaw tolerance, and is a crucial aspect of the safety assessment of structural components. Flaw tolerance in soft materials can be substantially different from that in traditional ones. As a matter of fact, the capacity of highly deformable materials to undergo large deformations with a significant rearrangement of the molecular network at the miscroscale in highly stressed regions can enhance such an ability, leading to an erroneous underestimation of their safety level against defect-driven failure, if traditional methods of analysis are employed. In the present research work, the mechanics of highly deformable notched plates is considered from the fail-safety point-of-view. Experimental, numerical and theoretical remarks are made in order to explain the mechanism of defect resistance in such a class of materials from a physically-based point-of-view

Presentazione del volume M. Guirguis - S. Muscuso - R. Pla Orquín (eds), Cartagine, il Mediterraneo centro-occidentale e la Sardegna. Società, economia e cultura materiale tra Fenici e autoctoni. Studi in onore di Piero Bartoloni (Le Monografie della SAIC

Presentation of the volume M. Guirguis - S. Muscuso - R. Pla Orquín (eds), Cartagine, il Mediterraneo centro-occidentale e la Sardegna. Società, economia e cultura materiale tra Fenici e autoctoni. Studi in onore di Piero Bartoloni (Le Monografie della SAIC 3), voll. I-II, Sassari: SAIC Editore, 2020-2021Presentazione del volume M. Guirguis - S. Muscuso - R. Pla Orquín (eds), Cartagine, il Mediterraneo centro-occidentale e la Sardegna. Società, economia e cultura materiale tra Fenici e autoctoni. Studi in onore di Piero Bartoloni (Le Monografie della SAIC 3), voll. I-II, Sassari: SAIC Editore, 2020-202

Tendenza evolutiva della spiaggia della Riserva Naturale della Sentina (San Benedetto del Tronto, AP)

Abstract The Regional Natural Reserve “Sentina” stretches itself for some 1.7 km along the southernmost end of the littoral area of San Benedetto del Tronto (AP) at the boundary with Abruzzo; it hosts one of the very few costal dunes still preserved in the Marche Region. Its gravelly-sandy beach in still natural, but is bound to the north by a long series of emerged barriers and to the south by a long (more than 300 m) pier; these structures noteworthy influence the retreat of the shoreline. In the area, a long monitoring (starting from 2000) has been carried out in order to interpret and quantify the modification occurred on both the emerged and submerged beach. During this time span, the shoreline retreated every year: up to 2006 its retreat has been evaluated in 27.7 m, with a local maximum of 33.5 m, whilst for the following 6 years (notwithstanding an artificial nourishment in 2008) it continued to retreat by 22.2, as an average. Therefore, in 12 years wave erosion resulted in some 50 m of backing; this also implied the loss of about 42’000 m2 of coastal dunes. Therefore, it is logical to assume that if no relevant intervention will be carried out, standing the almost absent nourishment deriving from the solid load of the Tronto R., in the next future the Sentina area will suffer progressive coastal erosion, with severe backing of the shoreline and distruction of the coastal dunes. Keywords: coastal erosion, monitoring, “Sentina” Reserve, coastal dune

Escursione lungo il litorale “piceno”

Abstract At the end of the National Symposium “Coastal erosion: defense, adaptation or withdrawal?”, organized by the Italian National Group for the Research on Coastal Environment (GNRAC), a short (half day) excursion has been organized to visit the “picena” coast (i.e. the portion of Marche littoral to the south of the Conero Mt.): some key location of which are here synthetically described. Namely, some of the main features of the coastline in Porto Sant’Elpidio, Porto Recanati and Sirolo are described. Key words: Adriatic Sea, Marche Region, coastal erosio

Gli effetti antropici nell’evoluzione storica della costa “Picena”

The historical evolution of the southern Marche shoreline (between the Conero promontory and the Tronto R. mouth) has been investigated comparing it with both natural and anthropic changes. The study started searching, georeferencing and digitizing in a GIS environment all the available historical maps and the observations deriving from archeological and documental findings, in order to reconstruct the position of the shoreline at different times, mostly for fluvial mouths. This allowed us to highlight that for the last two millennia anthropic interventions influenced coastal dynamics more than climate variations. For all the investigated sites a close relation between shoreline fluctuations and forestation/deforestation processes was clearly revealed. Among others, it emerged that river mouths progradation continued up to 1930, well after the end of the “Little Ice Age” (around 1850). The above relation is particularly striking for the last two centuries, for which we have both accurate maps and census of forested areas. During the XIX century, notwithstanding the warm climate favored slope protection, widespread deforestation resulted in a regular advance of shorelines (average rate about 4.95 m/y for the first half of the century and 1.08 m/y for the second half). The XX century featured a more irregular behavior with substantial retreat after the ‘30s: this derives almost exclusively from anthropic interventions in the river basins (construction of dams, river bed quarrying, river reshaping, abandonment of crops etc.) leading to a severe decrease of solid load. For the last few decades and at present, the most important factors driving the behavior of coastlines resulted to be the various interventions carried out along the beaches and in front of them to reduce erosion. Keywords: antropogenic impact, historical evolution, coastline, central-southern Marche, Adriatic Se

The sub-fossil red coral of Sciacca (Sicily Channel, Mediterranean Sea): colony size and age estimates

AbstractThe Mediterranean red coral, Corallium rubrum (L.), has been a valuable economic resource for more than 2000 years. The Sicily Channel and surrounding areas are one of the most famous red coral fishing grounds of the whole region, hosting the deepest ever found living colonies and large sub-fossil red coral deposits; the so-called Sciacca banks are a unique location in the whole Mediterranean Sea. In this paper, a morphometric description of this sub-fossil population is presented for the first time from studies of colonies in the collection of several coral factories from Torre del Greco (Naples), with radiocarbon age estimations and growth rate evaluations. From the results of this study, after several thousand years Sciacca red coral colonies maintained the organic matrix structure with evident annual discontinuities, allowing estimations of the annual growth rate (about 0.3 mm/year) and the average population age (about 33.5 years). These resulting data are similar to the values determined for deep-dwelling living red coral populations. The radiocarbon dating evidenced a range of ages, from 8300 to 40 years before 1950 CE, mostly falling between 2700 and 3900 YBP, suggesting that colonies accumulated over a wide span of time. In view of the tectonically active nature of the area, several catastrophic events affected these ancient populations, maintaining them in a persistent state of early-stage, structurally similar to the those in current over-exploited areas

Real Time Marine Data Acquisition: The Coastal Oceanographic Observatory Network in the Adriatic sea.

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Methods for measuring benthic nutrient flux on the California Margin: Comparing shipboard core incubations to in situ lander results

The objective of this study was to compare two techniques for estimating benthic fluxes of nutrients (nitrate, phosphate, and silicic acid) and Ge/Si flux ratios. In situ flux chambers were deployed, and cores were collected and incubated at 9 sites along the California margin in July 2001. Both techniques were successful at 8 sites, at depths from 100 to 3300 m. Flux chambers were deployed for 1 to 2 d, and cores were incubated for slightly longer on board the ship in a cold room. In some cases, core incubation flux temperature varied by up to 5°C from in situ temperature, and core incubation results were adjusted for this factor based on the effects of temperature on diffusivities and the adsorption of silicic acid. Sites studied had a range in nutrient fluxes of more than an order of magnitude, based on in situ chambers. The temperature-adjusted core incubation fluxes showed a similar, but slightly smaller range. Both methods had similar precision based on replicates, with uncertainties for high flux stations that were 5% to 20% of the mean. Only phosphate showed significant (95% confidence level) spatial variability in replicate cores; the larger in situ flux chambers had less spatial variability. The two techniques did show some systematic differences that are attributed to several artifacts created by core recovery. Silicic acid fluxes from cores were significantly lower than in situ fluxes at 2 sites; overall averages were about 80% of those for in situ chambers. The differences are attributed to reduced macrofaunal irrigation in incubated cores. Nitrate uptake in core incubations at 5 of 8 stations was significantly lower than in situ uptake; shipboard rates for all sites averaged about 66% of in situ chamber rates. This difference is attributed primarily to decreased denitrification rates in recovered cores in response to altered temperature and pressure. Phosphate fluxes from cores were significantly lower at only one site; overall, results for the two techniques were indistinguishable. Only one site had a significantly different Ge/Si flux ratio

NMR-based metabolomics for investigating urinary profiles of metal carpentry workers exposed to welding fumes and volatile organic compounds

IntroductionMetal carpentry includes a wide range of work activities such as welding and cutting metallic components, use of solvents and paints. Therefore, the employees in these types of activities are mainly exposed to welding fumes and volatile organic solvents. Here, we present an NMR-based metabolomic approach for assessing urinary profiles of workers in the same company that are exposed to two different risk factors.MethodsThe study enrolled 40 male subjects exposed to welding fumes, 13 male subjects exposed to volatile organic compounds of a metal carpentry company, and 24 healthy volunteers. All samples were collected, in the middle of the working week at fast. Thirty-five urinary metabolites belonging to different chemical classes such as amino acids, organic acids and amines were identified and quantified. Results were processed by multivariate statistical analysis for identifying significant metabolites for each working group examined, compared to controls.ResultsWorkers exposed to welding fumes displayed urinary increase in glutamine, tyrosine, taurine, creatine, methylguanidine and pseudouridine associated to oxidative impairment, while workers exposed to volatile organic compounds showed higher urinary levels of branched chain aminoacids.ConclusionOur work identified specific urinary profile related to each occupational exposure, even if it is below the threshold limit values

L’emergenza e i rapporti tra lo Stato e le Regioni

Forum sul rapporto tra Stato e Regioni al tempo del Coronaviru