Search results for "Cave"
showing 10 items of 606 documents
The scavenging of nitrogen compounds by clouds and precipitation:
1998
Model predictions of nitric acid scavenging by an air parcel model and a two-dimensional dynamic cloud model with detailed microphysics are compared with corresponding predictions for parameterized microphysics for the same initial conditions. In general the gas uptake proceeds slower in the model with parameterized microphysics than in the model with detailed microphysics and, the larger the drop size, results in a slower mass transfer. This behaviour can be explained by the inverse drop-radius dependency of the mass transfer coefficient and the time delays were a direct result of the microphysical parameterization. With the air parcel model for the scavenging of nitric acid, time delays i…
Improvement of oxidation resistance of polymer-based nanocomposites through sonication of carbonaceous nanoparticles
2020
Abstract The work aim is focused on two different aspects: first, the investigation of the effect of extended ultra-sound-assisted treatment (us) of carbonaceous nanoparticles, such as carbon nanotubes (CNTs) and carbon black (CB), on their radical scavenging activity, and second, the investigation of the oxidative resistance of polymer-based nanocomposites, containing us-treated CNTs and CB. Particularly, the CNTs and CB have been subjected to us sonication for different time intervals and the performed analysis reveals that both kinds of nanoparticles show decreased average hydrodynamic diameters and large content of surface defects. Really, the increased content of CNTs and CB defects, a…
Nano-hybrids based on quercetin and carbon nanotubes with excellent anti-oxidant activity
2016
Abstract Multi-functional nano-hybrids based on Quercetin (Q), a natural antioxidant, and functionalized Carbon Nanotubes (CNTs) have been formulated and used to prepare Ultra High Molecular Weight PolyEthylene (UHMWPE)-based nanocomposites. The study of the nanocomposites rheological behaviour shows that the immobilization of Q molecules onto CNTs outer surface leads to a beneficial effect on the state of the interface between polymer and nanoparticles. Additionally, the investigation of the thermo- and photo-oxidation processes reveals that the hybrids nanoparticles are able to exert a remarkable stabilizing action, due to strong physical interaction between Q and CNTs. In particular, the…
Tunable radical scavenging activity of carbon nanotubes through sonication
2016
Abstract Carbon nanotubes (CNTs) having controlled radical scavenging activity have been achieved tuning the content of their lattice defects induced by an ultra-sound (us) treatment. The reactivity of CNTs, subjected to ultra-sonication for different time intervals, toward 1,1-diphenyl-2-pycryl (DPPH) and hydroxyl (•OH) radicals has been estimated and related to defect concentration, evaluated through Raman spectrometry. The radical scavenging efficiency of ultra-sound treated CNTs (us-CNTs) increases with increasing the content of the structural defects, suggesting that the defect resulting from us treatment can be capitalized to obtain an amplified and controlled radical scavenging activ…
Influence of oxidation level of graphene oxide on the mechanical performance and photo-oxidation resistance of a polyamide 6
2019
The aim of this work is to study the relationship between the chemical-physical properties of graphene oxide (GO) and the performance of a polyamide 6 (PA6) in terms of mechanical reinforcement and resistance to UV-exposure. For this purpose, two samples of GO possessing different oxidation degrees were added (0.75 wt.%) to PA6 by way of a two-step technique and the materials achieved were carefully analysed from a morphological, chemical-physical, mechanical point of view. Photo-oxidation tests were carried out to assess the performance of this class of nanohybrids after 240 h of UV-exposure. The results reveal that both nanocomposites exhibit enhanced mechanical performance and durability…
Tidal notches, coastal landforms and relative sea-level changes during the Late Quaternary at Ustica Island (Tyrrhenian Sea, Italy)
2017
In this paper we present and discuss data concerning the morphostructural evolution at Ustica Island (Tyrrhenian Sea, Italy) during Late Quaternary. New insights on the relative sea-level changes of Ustica are coming from data collected during a geomorphological field survey around the island, together with the bathymetric analysis of the surrounding seabed and 14C datings on samples of speleothems, flowstones and marine shells found inside three selected sea caves. The survey was mainly accomplished on June 2015 through the first complete snorkel investigation off the about 18 km-long volcanic coast of the island, which allowed to precisely define location, relationship and morphometric fe…
Phytolith analyses from Khil and Kaf Taht el-Ghar (Western Maghreb): Plant use trajectories in a long-term perspective
2021
In this paper we present the results of phytolith investigations at two archaeological sites in northwestern Morocco: Khil (Tangier) and Kaf Taht el-Ghar (Tétouan). The two sites located in Western Maghreb, one on the Atlantic and one on the Mediterranean coast, were investigated in the framework of the AGRIWESTMED project. Phytolith analysis complemented archaeobotanical, geoarchaeological and archaeological investigations to better identify plant use during the entire occupation sequence. At Khil 16 samples have been studied, coming from two profiles excavated in two different caves of the same system – grotte B and grotte C – that span a chronology comprised between the early Neolithic a…
Radiocarbon dates, climatic events, and social dynamics during the Early Neolithic in Mediterranean Iberia
2016
Abstract Our goal in this paper is to examine the socioecological dynamics of the Early Neolithic period in Iberia in order to test the usefulness of temporal probability curves built from dated sites as a relative proxy for exploring possible links between trends in population patterns and climatic fluctuations. We compare the information for the entire Iberian Peninsula with four Mediterranean regions, investigating the climate–population relationships that emerge when we zoom into particular regions. We evaluate climatic and other possible causes of similarities in the shapes of temporal probability curves across the Peninsula, associated with demographic changes in the Early Neolithic s…
A Terrestrial Diet Close to the Coast: A Case Study from the Neolithic Levels of Nerja Cave (Málaga, Spain)
2017
Here we present an evaluation of faunal studies and new isotopic results on human and faunal remains from the first farmers at Nerja Cave (Malaga, Spain), and assess the data obtained from a regional perspective and on the basis of the archaeological and archaeozoological context. The evidence shows that the Neolithic peoples who inhabited the cave had a mainly terrestrial diet, even if living on the coastline and in a region with a high marine productivity, as observed during previous periods at the same cave. This sharp dietary shift occurring at the onset of the Neolithic for this region supports the hypothesis that different modes of exploitation during distinct time periods are best ex…
Late Upper Palaeolithic hunter-gatherers in the Central Mediterranean: New archaeological and genetic data from the Late Epigravettian burial Oriente…
2019
AbstractGrotta d’Oriente, a small coastal cave located on the island of Favignana (Sicily, Italy) is a key site for the study of the early human colonization of Sicily. The individual known as Oriente C was found in the lower portion of an anthropogenic deposit containing typical local Late Upper Palaeolithic (Late Epigravettian) stone assemblages. Two radiocarbon dates on charcoal from the deposit containing the burial are consistent with the archaeological context and refer Oriente C to a period spanning about 14,200-13,800 cal. BP. Anatomical features are close to those of Late Upper Palaeolithic populations of the Mediterranean and show strong affinity with Palaeolithic individuals of S…