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Photocatalytic behaviour of mesoporous Au-Cu/TiO2-SiO2 for the selective CO oxidation in H2-rich stream under simulated sunlight irradiation
No full textWith the aim of developing sustainable and economic catalysts, Au doped-transition metals have gained great interest thanks to their abundance and affordability. Moreover, they have shown a synergistic effect in degradation of pollutants and CO oxidation reactions [1]. This fact can be understood considering that the incorporation of transition metals in a photoactive matrix, such as titania, may turn out in new energy levels between valence and conduction bands and therefore inducing a shift of light absorption towards the visible light region.
In this work, Au-Cu (Au:Cu=1) nanoparticles were supported on a post-synthesis titania modified SBA-15 silica to be used in the preferential oxidation of CO in excess of hydrogen at room temperature and atmospheric pressure both in the dark and under simulated solar light irradiation (photo-CO-PROX) [2]. To study their textural, structural, chemical and optical properties, the samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (HR-TEM), adsorption-desorption of N2 at -196 °C, 13C and 29Si solid state NMR, X-ray photoelectron spectroscopy (XPS) and DRUV-vis spectroscopy. The synthesized Au-Cu/TiO2-SiO2 materials showed an ordered mesoporous network with high surface area and narrow pore size distribution (4.3 nm), exhibiting the main peaks of anatase phase. Incorporation of AuCu bimetallic phase was investigated by HR-TEM, that revealed the presence of very small nanoparticles (< 4 nm) homogenously distributed on the support and interacting with titania as assessed by XPS measurements. The photocatalysts were tested in the photo-CO-PROX and, in spite of the low gold and copper loading (Au 1.5 wt% and Cu 0.5 wt%), they resulted highly active and selective, with CO conversion and CO2 selectivity values of about 80% under simulated sunlight irradiation, due both to the presence of titania incorporated in SBA-15 and to the synergistic effect of Cu when alloyed with Au
Spectroscopic and Chemometric Comparison of Local River Sands with the Aggregate Component in Mortars from Ancient Roman Buildings Located in the X Regio Between the Livenza and Tagliamento Rivers, Northeast Italy
No full textA combined spectroscopic–chemometric approach is used to investigate the possible sources of material exploited by the Romans to build four domus and a public thermae complex (I century BC–II century AD) located in the X Regio portion between the rivers Livenza and Tagliamento in northeast Italy. The rounded grain shapes observed in the aggregates recovered from the mortar fragments suggest that the rivers flowing close to the archaeological sites are the most likely sources of material. Coarse-grained sediment samples from nine rivers and streams in this area are examined and their similarities to the aggregate samples evaluated. The diffuse reflection Fourier transform infrared (FT-IR) spectra of the sand samples in the 63–420 µm fraction, consisting mainly of carbonates and silicates, are studied and compared in suitable spectral ranges through principal components analysis. As an additional step, the relationship between the most significant scores plots and the composition of the samples is investigated using appropriate descriptive indexes obtained from the spectra. The analysis performed on the river sand spectra alone shows that the samples from the easternmost Lemene and Tagliamento rivers present a behavior distinct from that of the western rivers (Cosa, Livenza, Meduna, Meschio, and Noncello), in agreement with their present location and past history. All the aggregate spectra investigated are compatible with the spectral characteristics of the samples from the Tagliamento and Lemene rivers, except for those from the Torre di Pordenone site, which are more similar to the sand spectra of the western rivers
River landscapes and optimal channel networks
No full textWe study tree structures termed optimal channel networks (OCNs) that minimize the total gravitational energy loss in the system, an exact property of steady-state landscape configurations that prove dynamically accessible and strikingly similar to natural forms. Here, we show that every OCN is a so-called natural river tree, in the sense that there exists a height function such that the flow directions are always directed along steepest descent. We also study the natural river trees in an arbitrary graph in terms of forbidden substructures, which we call k-path obstacles, and OCNs on a d-dimensional lattice, improving earlier results by determining the minimum energy up to a constant factor for every d ≥ 2. Results extend our capabilities in environmental statistical mechanics
Predicting the response of fish and invertebrate assemblages to seagrass transplantations: assessment of the progress of habitat restorationin the Venice lagoon.
No full textOne of the major challenges to ensure effective restoration of estuarine habitats is to establish success criteria, allowingto determine whether the goalsof restoration are met. In the northern basin of Venice lagoon (northern Adriatic Sea, Italy), the LIFE project “SeResto” started in 2014 aiming at restoring seagrass meadows by means of small-scale manual transplantation of sods and rhizomes. The interventions are expected to increase the cover of Zostera marina and Z. noltei in the area, and to subsequently restore the typical features of faunal assemblages associated with seagrass meadows. The aim of this work is to propose a method to identify reference conditions and assess the progress of nekton (fish, decapods and cephalopods) assemblages at seagrass restoration sites.Nekton sampling took place from 2014 to 2017 during spring at eight transplantation sites. In spring 2016, five natural seagrass sites in the same area were additionally sampled, and physico-chemical water parameters and habitat structure (seagrass floristic composition, percent cover, canopy height, shoot density, leaf area index and epiphytal load) were also recorded. A multivariate approach based on GLMswas adopted, in order to disentangle the relative effect of water quality and seagrass habitat structure on nekton assemblages of natural habitats.Models were then employed to predict species composition of nekton fauna at each transplantation site under target abiotic and habitat conditions, allowing to identify the reference assemblages to evaluate the progress of fauna towards restoration goals. The analysis highlighted that desired restoration outcomes, i.e. presence of Z. marina and greater seagrass cover are positively linked to presence and density of some pipefishes (Syngnathidae), large gobies (Gobiidae) and some shrimps (Palaemonidae and Hippolytidae) in the nekton assemblage. Sites exhibiting better recovery of habitat structure also supported nekton assemblages more similar to reference conditions. However, none of the sites showed clear trajectories of progress, suggesting that more than three years are needed for nekton fauna to successfully colonise restored seagrass meadows in coastal lagoons
Seagrass restoration in Venice lagoon: integrate analysis of environmental parameters and ecological communities on transplanted sites.
No full textOver the past few decades seagrass meadows have shown a wide regression worldwide due to multiple anthropogenic impacts. During that period Venice lagoon experienced asignificant decrease of Zostera marina and Zostera noltei, particularly in the central and Northern basins (Site of Community Importance IT3250031).At present, most of the local anthropogenic pressures which caused seagrass decline have significantly decreased, creating the ecological conditions for a new colonization. The LIFE SeResto project (LIFE12 NAT/IT/000331) started in 2014 with the aim to restoreand consolidate water habitats no. 1150* in the Northern basin of Venice lagoon through thetransplantation of seagrass local species(mainly Z.marina and Z. noltei) on 35 sites.
An environmental monitoring was carried out on the transplantation sites, considering: seagrass transplantation success, abiotic parameters of waters and sediments, biological quality elements (BQEs) macrophyte, macrobenthos and fish fauna. Monitoring results were analyzed to investigate factors affecting transplant ssuccess and to assess changes inBQE secological status (sensu WFD)in the surrounding areas.
In the 17 sites transplanted in spring 2014 the mean seagrass cover after 30 months was ca. 60% of the intervention areas (10x10m), while in the other 18 sites transplanted in spring 2015 the mean cover was ca. 44.5%after 18 months.Rooting success greatly varied among sites ,ranging from areas where seagrass did not root (cover 0%) to areas with a fast and full colonization rate (cover 100%).
As expected, rooting success resultedstrictly relatedto nutrient concentration on water (DIN r= -0.71, TDP r=-0.76, TSS r=-0.85) and sediment (IP r= -0.86) and to low suspended solid concentration (TSS r=-0.88). Multivariate analysis indicates the presence of different clusters of sites identified on the basis of the environmental characteristics of water and sediment and reflects the coherence amongrooting success and the high ecological status of macrophyte (MaQI) and fish (HFBI) indexes. Macrophyte community showed a rapid increase of total number of species, with particular reference to the most sensitive, while changes in fish and macrobenthic communities were slower because seagrass meadows are not yet well-developed and the habitat recover is still in progress
Il quadro normativo ambientale nella Laguna di Venezia. Proposta di una nuova procedura di gestione dei sedimenti
No full textIn limine. Storie di una comunità ai margini della laguna
No full textIl volume costituisce la sintesi delle ricerche archeologiche e storiche avviate dall'Università Ca' Foscari di Venezia negli ultimi anni. Oltre l'analisi della sequenza, il volume contiene contributi specifici sui materiali (ceramiche, vetri, metalli), sul paleo-ambiente e, infine, le analisi antropologiche del cimitero. Nella parte conclusiva si traccia un nuovo profilo storico-archeologico dell'insediamento di Equilo dall'età romana fino al medioevo
How traces of pollutants in the environment modify bioremediation efficiency performed with Desulfovibrio vulgaris, and the advantage of an optimization protocol using soft chemicals
No full textMetaphors and translation: Some Notes on the Description of Pain in a XII century Persian Poem
No full textThe question of the translation of the figures of speech is a debated and complex field of studies. In the present work, after a brief introduction, I propose to ponder over with concrete examples on the translation of some figures of speech (metaphor, comparison and hyperbole) from Persian into Italian, taking as a source and representative text a passage from the poem Khosrow o Širin by Neẓāmi Ganjavi (XII century). This is a text of extraordinary imaginative and creative power, which represents a hard challenge for a translator, especially at a rhetoric level. Through the analysis of some lines that describe the pain of Princess Širin, I will try to verify methods, possibilities, strategies and defeats for their translation into Italian