We discuss the consequences of the quantum uncertainty on the spectrum of the electron emitted by the beta-processes of a tritium atom bound to a graphene sheet. We analyze quantitatively the issue ...recently raised by Cheipesh, Cheianov, and Boyarsky Phys. Rev. D 104, 116004 (2021), and discuss the relevant timescales and the degrees of freedom that can contribute to the intrinsic spread in the electron energy. We perform careful calculations of the potential between tritium and graphene with different coverages and geometries. With this at hand, we propose possible avenues to mitigate the effect of the quantum uncertainty.
The current wide use of manufactured nanomaterials (MNs) is leading to the release of nanoparticles (NPs) to water bodies. Aquatic organisms, including fish, are exposed to low concentrations of NPs ...for long periods of time being necessary to develop laboratory toxicity tests reflecting realistic conditions. Additionally, today there is a demand of in vitro assays respecting the 3Rs principle. Thus, the main aim of this work was to stablish an in vitro tool for the assessment of long-term NPs ecotoxicity. Considering the key role of liver in detoxification, a rainbow trout liver cell line, RTL-W1, was used. CuO NPs were chosen to validate this tool taking into account their important production level. Cells were exposed for 21 days to 25 or 100 μg CuO NPs/ml. Every seven days cells were split and one fourth of them transferred to a new plate with appropriate concentrations of NPs in culture medium. Lower concentrations of CuO NPs did not cause any deleterious effect, whereas higher concentrations led to significant mortality after 14 days and to the intracellular accumulation of Cu particles. Identical results were observed in cells exposed to CuSO4 at the same Cu concentrations. Therefore, the observed toxic effects might be mainly due to Cu2+ ions.
•Development of a tool for nanomaterials long-term ecotoxicity assessment in vitro•RTL-W1 cells were exposed to CuO NPs for 21 days at 24 h EC10 and EC50.•CuO NPs dissolved quickly being not detectable after six days exposure.•Lower concentrations did not induce toxicity but a long-term increased toxicity was observed with higher concentrations.•Similar results were detected after exposure with CuSO4 suggesting that toxic effects were probably due to ionic fraction.
Mercury contamination from historic cinnabar mines represents a potential risk to the environment. Asturias, in Northern Spain, was one of the largest metallurgic and mining producer areas of Hg in ...Europe during the 20th century until the end of activities in 1974. Mining operations have caused Hg release and dispersion throughout the area. In this study, soils collected from calcine piles and surrounding soils at an abandoned Hg mine and metallurgical plant in Mieres (Asturias, Spain) were distributed in different particle-size subsamples. Fractionation of Hg was performed by means of a Hg-specific sequential extraction procedure complemented with the selective determination of organic Hg fraction by a specific extraction method. Extremely high concentrations of total Hg were found in calcine piles. Concentrations and mobility of Hg decreased markedly with the distance in soils located 25 m both above and below the chimney of the metallurgical plant. The sequential extraction results indicated that Hg is primarily found as elemental Hg followed by sulfide Hg in the finest subsamples. However, this distribution is inverted in the coarser grain fractions where sulfide Hg prevails. Calcine piles exhibited exceptionally high values of mobile Hg (up to 5350 μg g(-1) in the finest subsample). Accumulation of Hg in the elemental Hg fraction was observed at decreasing grain size which is indicative of deposition of Hg vapors from the metallurgical plant. Enrichment of sulfide Hg was found in the finest subsamples of soils sampled below the chimney (up to 99 μg g(-1)). Significant organic Hg contents were observed in the soil samples (up to 2.8 μg g(-1)), higher than those found in other abandoned Hg mining sites. A strong correlation was observed between organic Hg and Hg humic and fulvic complexes, as well as with the elemental Hg fraction. This indicates that both humic and fulvic material and elemental Hg must be the primary variables controlling Hg methylation in these soils.
In Asturias (NW Spain) there are many abandoned mines, of which Hg mines are of particular significance from an environmental point of view, due to the presence of Hg and particularly As, which is ...found either in the form of specific (orpiment and realgar) or non-specific minerals (As-rich pyrite). The instability of these minerals leads to the presence of As-rich mine drainage and spoils heap leachates that enter surface waters or groundwaters. A study including the three most important Hg mines in the region (La Soterraña, Los Rueldos and El Terronal) has been conducted. Watercourses flowing through these mining areas are tributaries of the River Caudal, one of the most important rivers in the area. High concentrations of As were found in some of these waters, which were monitored over a period of three hydrological years and classified according to a water quality index. Those waters sampled close to the mines are generally of poor-to-bad quality, with low alkalinity and in some cases high metal content, but the quality of these waters improves with distance from the mines. The average mass load of As entering the River Caudal has been evaluated as: 200, 12 and 9,800 kg year
−1
from La Soterraña, Los Rueldos and El Terronal mine sites, respectively. Despite the constant input of about 10 tonnes of As per year, the total As concentration remains below analytical detection thresholds on account of the river’s high water flow. Nevertheless, an important part of this As load is presumably retained in the river sediments, representing a potential risk of pollution of the aquatic ecosystems.
A chemical, mineralogical and morphological characterization of 54 fragments of oil lamps found in two Spanish archaeological sites (
Cordoba and
Herrera de Pisuerga (
Palencia)) has been performed. ...Flame atomic absorption and emission spectrometry were used for the determination of Al
2O
3, CaO, Fe
2O
3, K
2O, MgO, MnO, Na
2O and TiO
2 as major constituents and Cu, Cr, Ni, Pb and Zn as minor and trace selected elements. Physical, mineralogical and morphological analyses were made by using dilatometry at constant heating rate for the thermal behaviour, X-ray diffraction spectrometry for the mineralogical composition and, in a group of selected samples, scanning electron microscopy and polarizing petrographic microscopy for the observation of thin layers and mineral identification. Separations of light and heavy minerals were carried out with bromoform and X-ray diffraction analysis was applied to both fractions. Multivariate statistical analysis was used to establish correlations between variables and to deduce factors which allow the gathering of oil lamp samples in groups as a function of their composition.
The results of these analyses allow the comparison among pieces and the establishment of conclusions about several aspects of their manufacture, the origin of the raw materials and the provenance of the oil lamps (local or imported). They provide information supporting certain archaeological hypothesis. For example, some oil lamps found in
Herrera de Pisuerga showed a clearly different physicochemical composition. They were probably brought from
Italy by the Roman Legions together with their initial furniture household.
Asturias (Northern Spain) has been an important mercury mining area during the twentieth century. The mining and smelting of ore has been the responsible for the large release of mercury to the ...aquatic and terrestrial environments in the area. The present work sought to evaluate the fractionation of mercury in stream sediments from the Caudal River basin in central Asturias by using sequential extraction. A novel five-step sequential extraction procedure was used to assess Hg partitioning. Total mercury concentrations varied between 12 and 443 mg.Kg−1. Sequential extractions revealed that both Elemental Hg and bound to sulfide Hg constituted the major forms of mercury in the samples.
In this work our purposes are (1) geochemical characterization of loess (‘primary loess’ or ‘true loess’ and ‘secondary loess’ or ‘loess-like deposits’) located in the centre of the Iberian ...Peninsula, (2) systematic study of element behaviour during pedogenesis and (3) evaluation of the suitability of using the geochemistry of loess to establish the average composition of these discontinuous aeolian sedimentary covers in central Spain. Several analyses were carried out on the bulk sample and on the sandy and clay fractions (mineralogical composition by X-ray diffraction, mineralogical studies of heavy minerals by petrographical microscopy and chemical composition by flame atomic absorption spectrometry). Loess from the Spanish central region has a local origin. The presence of gypsum in the ‘loess-like’ deposits reaches values two times higher than in ‘true loess’, and ‘true loess’ has a higher concentration of quartz, calcite and kaolinite. Regarding chemical composition, similar concentrations of Ca, K, Mg and Na were found, although it is important to note the higher concentration of Na in some of the samples.
An ion-exchange ICP-AES method for the determination of 14 rare earth elements (REEs) and Y in geological materials is described. The separation of REEs from Ba using a Dowex 50W-X8 cation resin is ...especially considered since Ba is an excellent internal standard for REE determination by this technique. Although total recovery with either HCl or HNO3 may be achieved, it is advantageous to use both acids sequentially. Volume and concentration of the acids are optimized attaining a quantitative separation of REEs from Ba by the introduction of the sample solution in a 1.75 mol/l HCl medium, followed by elution with 2 mol/l HNO3 to remove matrix elements and with 7 mol/l HNO3 to elute the analytes. The total elution volume is significantly reduced without decreasing the efficiency. The behaviour of the matrix constituents under the selected conditions is also studied, evaluating their elution percentages in each step. The final solution obtained contains only the REEs and Y, with the bulk of Sc and minor amounts of Cr, Fe, Hf and Ta. Experimental data for 5 geological reference standards (NIM-G, GSP-1, AGV-1, NIM-L and NIM-S) are reported. Good agreement between the present results and previously accepted values by various analytical techniques is observed.
The IFMIF-EVEDA beam dump must be able to stop deuteron continuous and pulsed beams with energies up to 9 MeV. The maximum beam power is 1.12 MW corresponding to a beam current of 125 mA. The design ...is based on a copper cone 2500 mm long, 300 mm aperture diameter, 5-6.5 mm thickness, whose inner surface faces the beam. The cooling is provided by water flowing at high velocity along its outer surface.
Electroforming of copper on an aluminum mandrel has been considered the most suitable manufacturing technology. Nevertheless some issues must be addressed before the final decision is taken. The joint of the flange at the aperture and the possibility of manufacturing different parts subsequently joining them by electroforming is analyzed by carrying out tensile tests with specimens with and without joints.
Mechanical properties and chemical composition are studied. The radiological impact of the measured impurities due to their activation under the deuteron flux is also assessed.
The comparison of the properties obtained with the different manufacturing possibilities will allow choosing the most adequate one.
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