Silica Meets Tannic Acid: Designing Green Nanoplatforms for Environment Preservation

Hybrid tannic acid-silica-based porous nanoparticles, TA-SiO2 NPs, have been synthesized under mild conditions in the presence of green and renewable tannic acid biopolymer, a glycoside polymer of gallic acid present in a large part of plants. Tannic acid (TA) was exploited as both a structuring directing agent and green chelating site for heavy metal ions recovery from aqueous solu-tions. Particles morphologies and porosity were easily tuned by varying the TA initial amount. The sample produced with the largest TA amount showed a specific surface area an order of magnitude larger than silica nanoparticles. The adsorption performance was investigated by using TA-5SiO2 NPs as adsorbents for copper (II) ions from an aqueous solution. The effects of the initial Cu2+ ions concentration and the pH values on the adsorption capability were also investigated. The resulting TA-SiO2 NPs exhibited a different adsorption behaviour towards Cu2+, which was demonstrated through different tests. The largest adsorption (i.e., ~50 wt% of the initial Cu2+ amount) was obtained with the more porous nanoplatforms bearing a higher final TA content. The TA-nanoplatforms, stable in pH value around neutral conditions, can be easily produced and their use would well comply with a green strategy to reduce wastewater pollution

Geothermal fluid circulation in a caldera setting: The Torre Alfina medium enthalpy system (Italy)

The Torre Alfina medium enthalpy geothermal field is located about 10 km north of the Bolsena caldera (Italy). The reservoir is a buried structural high consisting of fractured Meso-Cenozoic carbonate sequences and sealed by clayey flysch successions and Pliocene marine clays. We performed TOUGH2 numerical simulations, testing different model designs based on contrasting conceptual models. Results indicate that deep circulation is forced by the geometry of the reservoir and by the applied T and P gradients. We interpret the Torre Alfina field as a “blind” system, mostly recharged by lateral advection of heat and fluids from the Bolsena caldera deep high-enthalpy system, through the permeable caldera faults

A fast procedure for optimizing thermal protection systems of re-entry vehicles

The aim of the present work is to introduce a fast procedure to optimize thermal protection systems for re-entry vehicles subjected to high thermal loads. A simplified one-dimensional optimization process, performed in order to find the optimum design variables (lengths, sections etc.), is the first step of the proposed design procedure. Simultaneously, the most suitable materials able to sustain high temperatures and meeting the weight requirements are selected and positioned within the design layout. In this stage of the design procedure, simplified (generalized plane strain) FEM models are used when boundary and geometrical conditions allow the reduction of the degrees of freedom. Those simplified local FEM models can be useful because they are time-saving and very simple to build; they are essentially one dimensional and can be used for optimization processes in order to determine the optimum configuration with regard to weight, temperature and stresses. A triple-layer and a double-layer body, subjected to the same aero-thermal loads, have been optimized to minimize the overall weight. Full two and three-dimensional analyses are performed in order to validate those simplified models. Thermal-structural analyses and optimizations are executed by adopting the Ansys FEM code

Evoluzione tardo quaternaria del margine casertano della Piana Campana (Italia meridionale)

Vengono ricostruite, attraverso rilievi di campo e l’analisi di circa 300 sondaggi geognostici, le caratteristiche geologiche di superficie e di sottosuolo del settore settentrionale bordiero della Piana Campana nell’area di Caserta. Sono state distinte cinque unità litostratigrafiche del Pleistocene medio-superiore di cui due marinotransizionali (M1 e M2), presenti esclusivamente nel sottosuolo, e tre piroclastiche (V1, TGC, TGN). Su queste basi è stata ricostruita l’architettura stratigrafica dell’area di studio. L’unità più profonda è costituita da depositi marino-transizionali (M1) riferibile al Pleistocene medio-superiore; al di sopra di questi sono presenti vulcaniti incoerenti (V1), correlate con depositi ascritti all’Ignimbrite di Durazzano (~116 Ka), affioranti lungo il bordo orientale della Piana. Depositi prevalentemente transizionali (M2) si ritrovano in alcune aree meridionali al di sopra di V1. Vulcaniti riferibili al Tufo Grigio Campano (TGC; ~39 Ka) ricoprono le unità M2 e V1. L’unità più superficiale è costituita dal Tufo Giallo Napoletano (TGN; ~15 Ka) presente solo nella porzione media e bassa della Piana. Depositi alluvionali e detritico-colluviali riferibili al Pleistocene superiore – Attuale icoprono le unità vulcaniche più recenti. Le sezioni geologiche ricostruite evidenziano i rapporti geometrici tra le unità litostratigrafiche, dislocazioni del tetto delle unità M1 e V1 permettono di ipotizzare che l’attività tettonica si è protratta fino al Pleistocene superiore. I dati analizzati sono stati immessi in un database gestito in un Sistema Informativo Territoriale (SIT)

Hot Structure Design Modelling of Reusable Re-entry Vehicles

Next generation reusable re-entry vehicles must be capable of sustaining consistent repeated aero-thermal loads without damage or deterioration. This means that such structures must tolerate the high temperatures engendered by aero-thermal re-entry fluxes but also resist the internal stresses related to such temperature fields. The TPS concepts - successfully tested on the Space Shuttle for over thirty years - have been proved to be quite ineffective with respect to the reusability requirement: in fact, the TPS tiles are subjected to a complex after flight inspection/reparation management, which is not very efficient from a time/cost point of view. To overcome these limitations, for highly aero-thermally stressed structures the TPS concepts may be substituted by "hot structure" concepts, in which the structure itself is conceived to resist the aero-thermal fluxes without employing TPS tiles. In order to achieve such a goal, "hot structure" parts must employ high temperature materials and provide a good management of the temperature distribution in order to guarantee safe interfaces with cold parts. Moreover the total weight of the structure should be kept low in order to limit costs. In the present paper we present a simple model for the design and optimisation of "hot structures" for reusable re-entry vehicles. The model makes use of 2D finite elements but, through the imposition of temperature/structural constraints, performs one-dimensional analyses, therefore it is well adapted for optimisation purposes. Issued from the model are some hot structure configurations optimised for re-entry flight