Trace and rare earth elements contents of a Sardinian sedimentary Mn-rich deposit: preliminary results.

Mn oxides are important scavengers of trace elements from waters. They often form deposits with high metals concentrations that sometimes have economic significance. Within a thick sedimentary deposits of northern Sardinia, Mn oxide mineralization was found as both matrix and coatings on clasts of a conglomeratic deposit, and subrounded nodules in residual clays. Lithiophorite and birnessite are the sole Mn phases that are also accompanied by variable amounts of Fe oxides and hydroxides, clay minerals, and phyllosilicates. Chemical analysis of the studied samples revealed high concentrations of most of trace metals (Co, Ni, Zn, Cu, Ba, Y, U and Pb) and all rare earth elements (REE). The latter were used to provide the first hypothesis regarding environmental conditions and chemical processes determining the precipitation of Mn oxides

Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in Na-Cl brackish waters of north-western Sardinia, Italy

Abstract. Throughout the Mediterranean, salinization threatens water quality, especially in coastal areas. This salinization is the result of concomitant processes related to both seawater intrusion and water–rock interaction, which in some cases are virtually indistinguishable. In the Nurra region of northwestern Sardinia, recent salinization related to marine water intrusion has been caused by aquifer exploitation. However, the geology of this region records a long history from the Palaeozoic to the Quaternary, and is structurally complex and comprises a wide variety of lithologies, including Triassic evaporites. Determining the origin of the saline component of the Jurassic and Triassic aquifers in the Nurra region may provide a useful and more general model for salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activity and recent climatic change, the Nurra has become vulnerable to desertification and, in common with other Mediterranean islands, surface water resources periodically suffer from severe shortages. With this in mind, we report new data regarding brackish and surface waters (outcrop and lake samples) of the Na-Cl type from the Nurra region, including major ions and selected trace elements (B, Br, I, and Sr), in addition to isotopic data including δ18O, δD in water, and δ34S and δ18O in dissolved SO4. To identify the origin of the salinity more precisely, we also analysed the mineralogical and isotopic composition of Triassic evaporites. The brackish waters have Cl contents of up to 2025 mg L−1 , and the ratios between dissolved ions and Cl, with the exception of the Br / Cl ratio, are not those expected on the basis of simple mixing between rainwater and seawater. The δ18O and δD data indicate that most of the waters fall between the regional meteoric water line and the global meteoric water line, supporting the conclusion that they are meteoric in origin. A significant consequence of the meteoric origin of the Na-Cl-type water studied here is that the Br / Cl ratio, extensively used to assess the origin of salinity in fresh water, should be used with care in carbonate aquifers that are near the coast. Overall, δ34S and δ18O levels in dissolved SO4 suggest that water–rock interaction is responsible for the Na-Cl brackish composition of the water hosted by the Jurassic and Triassic aquifers of the Nurra, and this is consistent with the geology and lithological features of the study area. Evaporite dissolution may also explain the high Cl content, as halite was detected within the gypsum deposits. Finally, these Na-Cl brackish waters are undersaturated with respect to the more soluble salts, implying that in a climate evolving toward semi-arid conditions, the salinization process could intensify dramatically in the near future

Status of the Cylindical-GEM project for the KLOE-2 Inner Tracker

The status of the R&D on the Cylindrical-GEM (CGEM) detector foreseen as Inner Tracker for KLOE-2, the upgrade of the KLOE experiment at the DAFNE phi-factory, will be presented. The R&D includes several activities: i) the construction and complete characterization of the full-size CGEM prototype, equipped with 650 microns pitch 1-D longitudinal strips; ii) the study of the 2-D readout with XV patterned strips and operation in magnetic field (up to 1.5T), performed with small planar prototypes in a dedicated test at the H4-SPS beam facility; iii) the characterization of the single-mask GEM technology for the realization of large-area GEM foils.Comment: 4 pages, 10 figures, Presented at Vienna Conference on Instrumentation (Feb 15-20, 2010, Vienna, Austria). Submitted to the Proceeding

Antioxidant activity in Pothomorphe peltata

Abstract Leaves of Pothomorphe peltata (L.) Miq. (Piperaceae) are used locally as anti-inflammatory, antipyretic, hepatoprotective and diuretic infusions and to treat external ulcers and local infections in several parts of the Peruvian, Bolivian and Brazilian Amazon region. The antioxidant activity of different extracts of P. peltata was studied using the hydroperoxide-initiated chemiluminescence assay in liver homogenates, and the methanolic extract was found to have the highest antioxidant activity, with an IC 50 = 4 µg/ml. Aqueous and dichloromethane extracts did not show antioxidant activity. The extracts were further evaluated using the thiobarbituric acid-reactive substances (TBARS) assay. Finally, an assay of DNA sugar damage induced by Fe (II) salt was used to determine the capacity of the extracts to suppress the oxidative degradation of DNA. All the extracts showed antioxidant activity in the latter two bioassays. The methanolic extract showed the highest activity in reducing oxidative damage to DNA, with an IC 50 = 5 µg/ml. Since this extract was highly effective in reducing chemiluminescence and DNA damage, and because the latter activity could be due to the presence of compounds that bind to DNA, DNA-binding activity was studied using the DNAmethyl green (DNA-MG) bioassay. A 30% decrease in the initial absorbance of DNA-MG complex was observed in the methanolic extract at 1000 µg/ml, suggesting the presence of compounds that bind to genetic material. No DNA-binding activity was observed in the aqueous or dichloromethane extracts

Composition and structural modifications to the AI/AISI 316L sintered steel interface induced by heat treatments

After heat treatment, the aluminium coating, deposited on sintered AISI 316L austenitic stainless steel forms an interdiffusion layer. Aluminium diffuses beyond the layer/steel interface, mostly along the interconnected porosities, penetrating into the sintered steel for about 80 gm, and causing a nitrogen exchange reaction with the Cr2N phase. This leads to the formation of AlN particles. At the beginning these are tiny, then they subsequently coalesce and migrate outwards through the interdiffusion layer. The vapour phase aluminium diffusion is in accordance with thermodynamical data.At the layer/coated sintered steel interface, on the steel side, the cavity surfaces are covered by aluminium and chromium mixed films. In uncoated heat treated sintered steels, the chromium oxide films are present in all the volume. The anodic behaviour of aluminium coated and heat treated (700 -900°C) sintered steels is much better than that of the uncoated steels heat treated at the same temperatures.The improvement can be attributed to the Cr2N and Al reaction which makes passivation easier. With 1000°C heat treatment, a worsening is observed compared to the lower temperatures