1,170 research outputs found

    Compositional variation and zoning of epidote supergroup minerals in the Campi Flegrei geothermal field, Naples, Italy

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    Authigenic epidote supergroups are an abundant accessory mineral in the calcium–aluminum silicate and thermometamorphic hydrothermal zones of the Campi Flegrei (Phlegraean Fields) geothermal field located west of Naples, Italy. Geothermal exploration for high-enthalpy fluid produced drill core and cuttings to ∼ 3 km depth in the Mofete (MF1, MF2, MF5) and San Vito (SV1, SV3) wells, where measured down-hole temperatures of epidote-bearing samples range from 270–350 ∘C and from 285–390 ∘C for the Mofete and San Vito areas, respectively. Two epidote group (epidote, clinozoisite), some rare earth element (REE)-bearing, and two allanite group (allanite-(Ce), ferriallanite-(Ce)) minerals were identified by electron microprobe. The allanite group is light rare earth element (LREE, La–Gd) enriched, Ce dominant, with REE + Y that varies from 30.59 wt %–14.32 wt %. Complex compositional variation such as oscillatory, sector, and complex (mixed) zoning is a ubiquitous feature observed in the epidote group, which occurs as veins, in vugs, as various size masses, and as isolated single crystals. Compositional zoning is caused by variable Fe ↔ Al3+ substitution and XFe [(Fe3+) / (Fe3++ Al)] ranges from 0.06–0.33 (Fe3+=0.185–0.967 apfu). XFe tends to decrease with increasing temperature in the Mofete wells, but its distribution is more complex in the San Vito wells, which records recent fault displacement. The variety and complexity of the epidote supergroup zoning suggest rapid fluid composition and/or intensive parameter fluctuations in the local hydrothermal system.</p

    Introduction to the thematic issue: Mineral deposits exploration and environmental geochemistry: case studies in Italy and in China

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    Raw materials are fundamental to the economy, and hence to growth and jobs, and they are essential for maintaining and improving our quality of life. Securing reliable, sustainable and economic access to certain 'critical' raw materials is of growing concern around the globe. But it is as well a priority to acquire detailed information about the distribution of PTE and POP both at regional and local scales for environmental issues. The latter are of fundamental importance for environmental risk assessment and analysis that have a crucial role in the evaluation of human health risk, especially in mining and intensive urbanized areas. In addition, geochemical knowledge of the territory and mostly of top soils, where the main agricultural products grow, to become the foods for citizens, may be useful for land-use planning. Geochemical exploration methods are widely used to manage, visualize, analyse and interpret data for further identifying geochemical anomalies, for both the discovery of new ore bodies and for environmental purposes

    Optimization of graphene-based materials outperforming host epoxy matrices

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    The degree of graphite exfoliation and edge-carboxylated layers can be controlled and balanced to design lightweight materials characterized by both low electrical percolation thresholds (EPT) and improved mechanical properties. So far, this challenging task has been undoubtedly very hard to achieve. The results presented in this paper highlight the effect of exfoliation degree and the role of edge-carboxylated graphite layers to give self-assembled structures embedded in the polymeric matrix. Graphene layers inside the matrix may serve as building blocks of complex systems that could outperform the host matrix. Improvements in electrical percolation and mechanical performance have been obtained by a synergic effect due to finely balancing the degree of exfoliation and the chemistry of graphene edges which favors the interfacial interaction between polymer and carbon layers. In particular, for epoxy-based resins including two partially exfoliated graphite samples, differing essentially in the content of carboxylated groups, the percolation threshold reduces from 3 wt% down to 0.3 wt%, as the carboxylated group content increases up to 10 wt%. Edge-carboxylated nanosheets also increase the nanofiller/epoxy matrix interaction, determining a relevant reinforcement in the elastic modulus

    Int J Environ Res Public Health

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    Few studies have explored temperature-mortality relationships in China, especially at the multi-large city level. This study was based on the data of seven typical, large Chinese cities to examine temperature-mortality relationships and optimum temperature of China. A generalized additive model (GAM) was applied to analyze the acute-effect of temperature on non-accidental mortality, and meta-analysis was used to merge data. Furthermore, the lagged effects of temperature up to 40 days on mortality and optimum temperature were analyzed using the distributed lag non-linear model (DLNM). We found that for all non-accidental mortality, high temperature could significantly increase the excess risk (ER) of death by 0.33% (95% confidence interval: 0.11%, 0.56%) with the temperature increase of 1 \uc2\ub0C. Similar but non-significant ER of death was observed when temperature decreased. The lagged effect of temperature showed that the relative risk of non-accidental mortality was lowest at 21 \uc2\ub0C. Our research suggests that high temperatures are more likely to cause an acute increase in mortality. There was a lagged effect of temperature on mortality, with an optimum temperature of 21 \uc2\ub0C. Our results could provide a theoretical basis for climate-related public health policy.26950139PMC480894

    a robust approach to the design of an electromagnetic shield based on pyrolitic carbon

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    A robust approach to the design of an electromagnetic shield based on ultra-thin pyrolytic carbon (PyC, 5 ÷ 110 nm) films is proposed. Finite Element Method (FEM) simulations and Monte Carlo based tolerance analysis are used to show that even a deviation of 15 ÷ 20% from the nominal values of the most important design parameters of the PyC film, i.e. its thickness and sheet resistance, does not significantly affect the wanted level of electromagnetic interference shielding efficiency (EMI SE). The ranges of the SE show that EMI shield based on PyC film is characterized by a robust behavior with respect to the variation of such parameters due to the production processes. Therefore, since the PyC can be produced on a scalable basis, is chemically inert, significantly transparent in the visible range and can be deposited onto both metal and dielectric substrates, including flexible polymers, it may be appropriate for the highly demanding technological needs associated to the graphene revolution and can be de..

    Mathematical model for preoperative identification of obstructed nasal subsites

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    The planning of experimental studies for evaluation of nasal airflow is particularly challenging given the difficulty in obtaining objective measurements in vivo. Although standard rhinomanometry and acoustic rhinometry are the most widely used diagnostic tools for evaluation of nasal airflow, they provide only a global measurement of nasal dynamics, without temporal or spatial details. Furthermore, the numerical simulation of nasal airflow as computational fluid dynamics technology is not validated. Unfortunately, to date, there are no available diagnostic tools to objectively evaluate the geometry of the nasal cavities and to measure nasal resistance and the degree of nasal obstruction, which is of utmost importance for surgical planning. To overcame these limitations, we developed a mathematical model based on Bernoulli's equation, which allows clinicians to obtain, with the use of a particular direct digital manometry, pressure measurements over time to identify which nasal subsite is obstructed. To the best of our knowledge, this is the first study to identify two limiting curves, one below and one above an average representative curve, describing the time dependence of the gauge pressure inside a single nostril. These upper and lower curves enclosed an area into which the airflow pattern of healthy individuals falls. In our opinion, this model may be useful to study each nasal subsite and to objectively evaluate the geometry and resistances of the nasal cavities, particularly in preoperative planning and follow-up

    ‘We have a Common Past, a Common Present and a Common Future’ Postcolonial Gendered Memories of the Eritrean Diaspora

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    Vivo con Domenica GhideiBiidu e Elisabetta Hagos nel 2009. In quanto componentidella diaspora eritrea in Europa, Ghidei Biidu e Hagos contribuiscono con questa intervista alla memoria della dominazione coloniale italiana nel Corno d’Africa sullabase del patrimonio di conoscenze che entrambe hanno ereditato dalle propriefamiglie.L’intervista si sviluppa lungo delle line di analisi e riflessione che rendono con efficacia l’importanza della dimensione di genere nel movimento nazionalista eritreoe nelle migrazioni di tipo postcoloniale e diasporico, così come nel processo dimemorizzazione che le ha accompagnate. S’illustrano inoltre la dimensione culturalee quella simbolica della relazione attuale fra popolazioni ex colonizzate ed excolonizzatrici. Infine, quest’intervista rappresenta un contributo originale nell’ottica del ‘fare storia’ rispetto al ruolo particolare che hanno avuto le donne eritree nei periodi di transizione politica e nelle connessioni fra Eritrea, Etiopia e Italia
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