Life on bottles: Colonisation of macroplastics by freshwater biota.

While rivers are known to be the main vectors of plastics to the sea, it seems surprising that studies on interactions (e.g. colonisation/entrapment and drift) between macroplastics and biota continue to remain largely neglected, notwithstanding they represent unexpected threats to freshwater biota and riverine habitats. To fill these gaps, here we focused on the colonisation of plastic bottles by freshwater biota. To do so, we collected 100 plastic bottles from the River Tiber in summer 2021. Overall, 95 bottles were colonised externally and 23 internally. Specifically, biota mainly occurred within and outside the bottles rather than plastic pieces and organic debris. Moreover, while bottles were externally covered mainly by vegetal organisms (i.e. macrophytes), they internally entrapped more animal organisms (i.e. invertebrates). The taxa most occurring within and outside the bottles belonged to pool and low water quality-associated taxa (e.g. Lemna sp., Gastropoda, and Diptera). In addition to biota and organic debris, plastic particles also occurred on bottles reporting the first observation of 'metaplastics' (i.e. plastics encrusted on bottles). Furthermore, we observed a significant positive correlation between the colonising taxa abundance and the bottle degree degradation. In this regard, we discussed how bottle buoyancy may change due to the organic matter on the bottle, affecting bottle sinking and transport along rivers. Our findings might be crucial for understanding the underrepresented topic of riverine plastics and their colonisation by biota, given that these plastics may act as vectors and cause biogeographical, environmental, and conservation issues to freshwater habitats.

Mapping at the nanometer scale the effects of sea-salt derived chlorine on cinnabar and lead white by using delayed image extraction in ToF-SIMS.

In this work, an innovative analytical approach focused on the use of advanced imaging techniques for the chemical mapping of degradation and/or restoration products is proposed. A representative cross-section showing a very complex stratigraphy from the Saint Wilgefortis Triptych (Hieronymus Bosch), exhibited in the Galleria dell'Accademia di Venezia, was investigated. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) experiments were performed using a time-of-flight detector operating in the so-called delayed extraction mode. The time delay applied during the extraction of the secondary ions permitted mass spectra to be obtained with an excellent mass resolution and chemical maps with nanometer scale spatial resolution. The painting's cross-section was also analysed at the micrometer scale by micro-Fourier transform infrared spectroscopy (micro-FTIR). The combined analytical approaches highlighted the colocalization of lead chloride, oxychloride, and hydroxychloride ions, suggesting the transformation of lead white ((PbCO3)2Pb(OH)2) into laurionite (PbClOH). Furthermore, chlorine appears evenly diffused in the cinnabar (HgS) layer, inducing the alteration of its more external part into calomel (Hg2Cl2). In fact, from the chemical maps the presence in the sample of an unaltered portion of the cinnabar layer is evident. Such degradation products were probably due to the exposure of the painting to a chloride-rich atmosphere for a long time. This led to a global blackening of the painting. To protect the painting from aggressive chemical species, siloxane compounds were probably used as a modern restorative treatment. ToF-SIMS chemical maps revealed permeation of the silicon-based consolidants within the sample's cracks and no interaction products with the other constitutive materials of the painting were found. Finally, the presence of different lead soaps was detected in correspondence with the lead white layer.

Magnetic mesoporous silica nanostructures: investigation of magnetic properties.

Magnetic mesoporous silica (MS) nanocomposites provide the possibility of generating multi-functional objects for application in different technological areas. This paper focuses on the magnetic properties of nanocomposites constituted by spinel iron oxide nanoparticles (magnetic nanoparticles (MNPs), < D > ≈ 8-9 nm) embedded in an MS matrix. The mesoporous structure of the silica matrix and the presence of the nanoparticles inside clearly emerge from transmission electron microscopy (TEM) measurements. Low temperature (5 K) field-dependent magnetization measurements reveal saturation magnetization (MS ) close to bulk value (M S bulk ∼ 90 emu g-1) for both MNPs and MNP/MS nanocomposites, indicating that the presence of silica does not affect the magnetic features of the single MNPs. Moreover, the dependence of the remanent magnetization on field (i.e. δM plots) at low temperature has shown a small but evident decrease of interaction in an MNP/MS sample with respect to MNP samples A m2 Kg-1. Finally, a partial orientation of the easy axis is observed when the MNPs are embedded in the silica matrix.

Influence of concentration and anion size on hydration of H+ ions and water structure.

Neutron diffraction experiments with hydrogen isotope substitution on aqueous solutions of HCl and HBr have been performed at concentrations ranging from 1:17 to 1:83 solute per water molecules, at ambient conditions. Data are analyzed using the empirical potential structure refinement technique in order to extract information on both the ion hydration shells and the microscopic structure of the solvent. It is found that the influence of these solutes on the water structure is less concentration dependent than that of salts or hydroxides. Moreover protons readily form a strong H-bond with a water molecule upon solvation, at all proportions. The majority of them is also bonded via a longer bond to another water molecule, giving a prepeak in the g(OwOw). At high solute concentration, the second water molecule may be substituted by the counterion. In particular at solute concentrations of the order of 1:17 or higher, all protons have an anion within a distance of 4.5 A.

Applications of Raman spectroscopy to library heritage.

This work reports some different applications of Raman spectroscopy, a high sensitive non-destructive technique, to the conservation of Library Heritage. By Raman spectroscopy we were able to detect the chemical mechanisms leading to cellulose degradation, identifying the different functional groups formed during the paper ageing. This kind of information is fundamental to choose a suited restoration treatment. A second reported application is the identification of pigments used to decorate paper and parchments. We report some results obtained from analysis of a XV and a XIII century illuminations.