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HfO2can assume different crystalline structures, such as monoclinic, orthorhombic, and cubic polymorphs, each one characterized by unical properties. The peculiarities of this material are also strongly related to the presence of doping elements in the unit cell. Thus, the present paper has the main purpose of studying and comparing twelve different systems characterized by diverse polymorphs and doping percentages. In particular, three different crystalline structures were considered: the monoclinicP21/c, the orthorhombicPca21, and the cubicFm3̲3¯mphases of HfO2. Each one has been studied by using Y as a doping agent with three different contents: 0% Y:HfO2, 8% Y:HfO2, 12% Y:HfO2, and 16% Y:HfO2. For all the systems, density functional theory (DFT) methods based on PBE/GGA, and on the HSE hybrid functionals were used to optimize the geometry as well as to study their optical properties. Depending on the polymorphs, Y affects the formation energy in different ways and causes changes in the optical properties. When the percentage of Y did not exceed 12%, a stabilization of the cubic phase fraction and an increase of the dielectric constant was observed. Additionally, the calculated optical bandgap energies and the refractive index are examined to provide an overview of the systems and are compared with experimental data. The bandgaps obtained are in perfect agreement with the experimental values and show a slight increase as the doping percentage grows, while only minor differences are found between the three polymorphs in terms of both refractive index and optical band gap. The adopted first principles study generates a reasonable prediction of the physical-chemical properties of all the systems, thus identifying the effects of doping phenomena.

We have studied the structural, electronic, magnetic, and optical properties of the VO2(B) polymorph using first-principles calculations based on density functional theory (DFT). This polymorph was found to display four optimized structures namely VO2(B)PP, VO2(B)LP, VO2(B)PPD, and VO2(B)LPDusing the generalized gradient approximation (GGA) PBE exchange-correlation functional by including/excluding van der Waals interaction. Our derivation provides a theoretical justification for adding an on-site CoulombUvalue in the conventional DFT calculations to allow a direct comparison of the two methods. We predicted a zero bandgap of the VO2(B) structure based on GGA/PBE. However, by GGA/PBE + U, we found accurate bandgap values of 0.76, 0.66, and 0.70 eV for VO2(B)PP, VO2(B)LP, and VO2(B)PPD, respectively. The results obtained from DFT + U were accompanied by a structural transition from the metallic to semiconductor property. Here, we verified the non-magnetic characteristic of the monoclinic VO2(B) phase with some available experimental and theoretical data. However, the debate on the magnetic property of this polymorph remains unresolved. Imaginary and real parts of the dielectric function, as computed with the GGA/PBE functional and the GGA/PBE + U functional, were also reported. The first absorption peaks of all considered geometries in the imaginary part of the dielectric constants indicated that the VO2(B) structure could perfectly absorb infrared light. The computed static dielectric constants with positive values, as derived from the optical properties, confirmed the conductivity of this material. Among the four proposed geometries of VO2(B) in this study, the outcomes obtained by VO2(B)PPDreveal good results owing to the excellent consistency of its bandgap, magnetic and optical properties with other experimental and theoretical observations. The theoretical framework in our study will provide useful insight for future practical applications of the VO2(B) polymorph in electronics and optoelectronics.

This work aimed to precisely evaluate the physical properties of vanadium dioxide (M), particularly the optical characteristics. We employed different exchange-correlation functionals to determine the phase stability, band gap properties, and optical characteristics of an experimentally recognized monoclinic VO2(M) polymorph. The calculations not only correctly interpreted the VO2(M) origin but also predicted other optical properties including the extinction coefficient (k�) and refractive index (n�), which have not been reported in experimental measurements. Phonon dispersion calculations confirmed the presence of negative frequencies for acoustic modes in the phononic curves. When the HSE functional correctly reproduced the experimental band gap, here for the first time, our calculations based on PBE and PBEsol yielded non-zero electronic bandgaps of 0.23 and 0.15eV for bulk VO2(M). Our predictions showed that semi-local functionals can adequately predict the semiconductor properties of VO2(M) and performed better than all previously reported theoretical works on nulled band gaps. In addition to the better prediction of the peak position in the absorption spectra with HSE hybrid functional, this method also reasonably well described the static dielectric constant of 7.54, showing an excellent match to the experimental values. In general, the results of this study reveal that hybrid functionals yield superior outcomes compared to semi-local functionals for optical properties of a VO2(M) polymorph. Our results suggest that the PBEsol + HSE approach allows the efficient characterization of smart materials for electronic and optoelectronic applications.

I sedimenti rappresentano la principale sede di accumulo di specie chimiche organiche ed inorganiche veicolate dalle acque fluviali alle aree marino-costiere. Svariati sono gli studi incentrati sulla geochimica dei sedimenti in termini di presenza, distribuzione e mobilità di contaminanti organici ed elementi in tracce potenzialmente tossici (Covelli et al., 2001). Tuttavia, poche sono le informazioni ad oggi esistenti relativamente a quelli che vengono definiti contaminanti emergenti, tra cui rientrano gli elementi delle Terre Rare (Rare Earth Elements, REE). Le REE comprendono 17 elementi metallici che includono l’intera serie dei lantanidi, unitamente allo scandio (Sc) e all’ittrio (Y) e vengono generalmente distinte in REE leggere e pesanti (LREE, HREE) in funzione del peso atomico. Nonostante siano definiti rari, questi elementi sono piuttosto diffusi nella crosta terrestre e ampiamente utilizzati in attività agricole, ospedaliere e in ambito industriale per la produzione di svariati dispositivi tecnologici di uso quotidiano. Per queste ragioni, la loro presenza in diverse matrici ambientali quali sedimenti, acque eparticellato in sospensione, è spesso oggetto di studio da parte della comunità scientifica internazionale. Infatti, le REE possono essere utilizzate come traccianti di fenomeni naturali, come processi erosivi, ma anche di attività antropiche (Viers et al., 2009; Piper and Bau, 2013; da Silva et al., 2018). Questo studio si pone come obiettivo una valutazione preliminare della presenza e distribuzione delle REE nei sedimenti superficiali dell’Alto Adriatico, rappresentativi di un’area compresa tra il Golfo di Trieste e il delta del fiume Po. Questi sedimenti sono stati oggetto di una precedente indagine sulla contaminazione da metalli pesanti e da idrocarburi nei sedimenti superficiali dei mari italiani (CoNISMa, 2001). Di conseguenza, il presente studio si propone di ampliare le informazioni già esistenti allo scopo ultimo di valutare l’origine di questi elementi unitamente alla presenza di eventuali anomalie nelle concentrazioni delle REE dovute a potenziali contributi antropici.

Human skin forms a unique interface between the body and the external environment. Its main role is to protect the internal organs from external factors. Notably, the outermost skin layer, stratum corneum, forms a remarkable barrier for permeation of xenobiotics in general, but unfortunately it may become an entry route of hazardous substances. Metals can penetrate and permeate the skin inducing local effects such as skin sensitization with allergic contact dermatitis and potential metals diffusion into the bloodstream with systemic intoxication[1] [2]. Metals in nano dimensions penetrate and permeate the skin in higher amount[3] [4] compared to bulk materials due to their smaller dimensions[5].Therefore, if the stratum corneum is damaged to various factors such as inflammation, desquamation, defects in lipid distribution or epidermal thickening, the transcutaneous passage of a molecule is expected to be drastically enhanced[6] [7]. In this study, we investigate the percutaneous penetration of metals from the road dust powder in intact as well damaged skin to mimic the effect of skin lesions. In addition, porcine and human skin were compared as skin models. The certified reference material BCR®-723 provided by the European Institute for Reference Materials and Measurements was used as road dust formulation. To evaluate the extent of ionization of metals from BCR®-723, the dissolution of powder in synthetic sweat solutions at two different pH (pH 4.5, 6.5) was carried out. Periodic quantification of metals concentration was monitored and analyzed via inductively coupled plasma - optical emission spectroscopy (ICP-OES). The choice of synthetic sweat solution at pH 4.5 was dictated to reproduce the workplace conditions. Dermal absorption from donor compartment containing metals was monitored for 24 hours. The amounts of metals retained in skin were quantified post-exposure by inductively coupled plasma - mass spectrometer (ICP-MS). Percutaneous absorption of lead (Pb) was higher in both intact skin models (549 ng/cm2 in porcine skin vs 68.80 ng/cm2 in human model). Moreover, cobalt (Co) accumulation was higher in porcine skin reaching a value of 518 ng/cm2 than those found in human skin (1.85 ng/cm2). In contrast with the observations reported in human skin model, chromium (Cr) achieved the lowest skin absorption in porcine model (183 ng/cm2). As expected, metals permeation on damaged skin was enhanced due to the removal of the barrier function. These consequence differences may be due to the skin tissues, but pig skin appeared as the most suitable replacement for human skin.

Sediments are considered reservoirs of contaminants, but they can also act as a secondary source of contamination since remobilisation processes at the sediment-water interface (SWI) may affect the water quality (Caplat et al., 2005; Petranich et al., 2018). The estuarine system of the Timavo River is located in the Gulf of Trieste (northern Adriatic Sea). The innermost sector of the estuary was recognised as the most critical area showing high concentrations of potentially toxic elements (PTEs) in sediments and scarce water circulation which led to a permanent oxic-hypoxic interface along the water column (Pavoni et al., 2020). Field activity was performed before (June) and after (September) the forced aeration of a system of porous pipes laid on the bottom aiming at re-oxygenating the water column in summer. Sampling was carried out along the water column, short sediment cores were collected to investigate both solid phase and porewaters and in situ benthic chamber experiments were conducted at the SWI. The primary aim of the work was to understand if and how biogeochemical processes may affect PTE (As, Cr, Hg, Fe, Mn, Ni, Pb, V) mobility and related fluxes at the SWI. The water column was found to be oxygen stratified and hypoxia occurred at the bottom, mostly in June (2.29 mg/L) when reductive conditions were also observed (-58 mV). As a result, dissolved PTEs increased with depth reaching maximum values at the bottom due to dissolution/desorption processes of Fe and Mn oxy-hydroxides (Dellwig et al., 2010). This evidence was confirmed by the benthic chamber experiments highlighting a gradual oxygen depletion inside the chamber due to organic matter remineralisation with subsequent increase of dissolved PTEs. The porewater profiles were found to be different between the two campaigns showing the highest PTE concentrations in June, mostly at the top of the sedimentary sequence suggesting that release of PTEs at the SWI is promoted in hypoxic conditions.

Decommissioned mines represent a worldwide concern for the environment even for decades to hundreds of years since the activities ceased, and also in those areas located at long distances from the mining sites. The most important mining district of the Friuli Venezia Giulia region is the Pb-Zn Raibl mine, sited in the NE sector of the Julian Alps, near the border with Austria and Slovenia. The mine had a secular history since the first evidence of mining activity is dated to 1320 whereas it closure is dated back to 1991. Only in the 1976-1991 period, almost 4 million tons of mine tailings, products from milling and enrichment (flotation) processes of sphalerite (ZnS) and galena (PbS), have been stored in a tailings impoundment nearby the main stream flowing the area, the Rio del Lago creek. The tailings contain very high concentrations of base metals (Zn, Pb and Fe) and potentially toxic trace elements (PTEs: As, Cd, Tl, Sb). The site is currently under remediation to mitigate the impact on the environment, however, since the availability of such elements in the stream waters represent a concern for the freshwater ecosystem, the water quality is constantly monitored. Ten years of groundwater monitoring results in several piezometers in the area conducted by ARPA FVG and the University of Trieste are presented. The time-series of the hydrochemistry evolution of tailings groundwaters has given the opportunity to observe the long- and short-term variations of elemental concentrations, thus suggesting the processes that lead the release of potential toxic elements (Tl, Zn and Pb) to groundwaters and some possible scenarios about future perspectives of contamination. The short-term hourly data from groundwaters, entrapped in the tailing ponds, indicate high frequency relationship between hydrology and oxidation of sulfides that release PTEs. On the contrary, long-term hydrochemical series indicate that groundwaters inside the ponds are generally depleting in dissolved metals, due to both remediation actions and chemical depletion of the source. Groundwaters undergo a progressive enrichment of the main PTE concentrations, although this enrichment is limited to a few hundreds of meters downstream the impoundment. Time-series analysis on the decay of PTEs performed with first-order rate constants (Newell et al., 2002), estimates that the dissolved metal contents in groundwater entrapped in the tailings could drop below the national law limits in a time interval from a couple of years to some decades. On the contrary, uncertain future scenarios about downstream enrichment have arisen.

Mercury (Hg) contamination in the Gulf of Trieste (GT, northern Adriatic Sea) is due to historical mining activity in Idrija (Slovenia) and still represents an environmental issue of great concern (Covelli et al., 2001; Covelli et al., 2021). Indeed, the freshwater inputs from the Isonzo/Soča River have been identified as the main source of Hg into the GT. At the river mouth, the element was found to be mainly associated with the suspended particulate matter, especially following periods of medium-high river discharge and river plume events in the GT (Covelli et al., 2006; 2007). The primary aim of this research is to evaluate the occurrence and distribution of both dissolved (DHg) and particulate (PHg) Hg along the water column in the northernmost sector of the GT, a shallow and sheltered embayment suitable for the accumulation of fine sediments and contaminants. In order to achieve this objective, sediment and water samples were collected at six sites which were representative of different targets, such as mussel farming and tourism activities. Moreover, different environmental conditions including unperturbed and perturbed hydrological conditions, induced by both natural and anthropogenic factors, were taken into account. The amount of Hg in the surface sediments (0.77–6.39 μg g-1) as well as the relationship between the Hg concentration and the percentage of the 2-16 μm grain size fraction from this study were found to be consistent with previous research focused on the whole Gulf, thus testifying the common origin of the sediment. Results showed a notable variability of DHg (0.07–149 ng L-1) and PHg (0.39–12.5 ng L-1) depending on the interaction between riverine and meteo-marine hydrological conditions at the time of sampling. Mercury was found to be mainly partitioned in the suspended particles and elevated values of PHg were observed following periods of high discharge from the Isonzo/Soča River confirming that the river discharge may represent an important factor in regulating the amount of PHg in the GT.

Sediments often act as reservoirs of contaminants, but they can also be considered a secondary source of contamination due to remobilisation processes at the sediment-water interface (SWI) which may affect the quality of the overlying water and aquatic biota [1,2]. The estuarine system of the Timavo/Reka River is located in the Gulf of Trieste (northern Adriatic Sea) and the innermost sector of the estuary was recognised as the most critical area. There, elevated concentrations of potentially toxic trace elements (PTEs) were detected in surface sediments and the scarce water circulation led to a permanent oxic-hypoxic interface along the water column [3]. This research aims at understanding if and how biogeochemical processes may affect PTE (As, Cr, Hg, Fe, Mn, Ni, Pb, V) mobility and related fluxes at the SWI. Sampling activities were performed before (June) and after September) the forced aeration by means of a system of porous pipes laid on the bottom with the aim to re-oxygenate the water column in summer. Water aliquots were sampled along the water column, short sediment cores were collected to investigate the solid (sediments) and dissolved (porewater) phases and in situ benthic chamber experiments were conducted at the SWI. Results showed that the water column was oxygen stratified and hypoxic conditions were observed in the bottom water layer, mostly in June (2.29 mg/L of dissolved oxygen) when reductive conditions also occurred (-58 mV). Consequently, dissolved PTE concentrations increased with increasing depth and were maximum at the bottom due to dissolution/desorption processes involving Fe and Mn oxy-hydroxides [4]. A gradual oxygen depletion was also observed inside the chamber during the benthic chamber experiments testifying to organic matter remineralisation processes and subsequent increase of dissolved PTEs. Regarding PTE profiles in porewater, the highest PTE concentrations were observed in June, especially at the top of the sedimentary sequence implying that hypoxic conditions may promote the release of PTEs at the SWI.

The dystroglycan adhesion complex consists of two noncovalently interacting proteins: alpha-dystroglycan, a peripheral extracellular subunit that is extensively glycosylated, and the transmembrane beta-dystroglycan, whose cytosolic tail interacts with dystrophin, thus linking the F-actin cytoskeleton to the extracellular matrix. Dystroglycan is thought to play a crucial role in the stability of the plasmalemma, and forms strong contacts between the extracellular matrix and the cytoskeleton in a wide variety of tissues. Abnormal membrane targeting of dystroglycan subunits and ? or their aberrant post-translational modification are often associated with several pathologic conditions, ranging from neuromuscular disorders to carcinomas. A putative functional hotspot of dystroglycan is represented by its intersubunit surface, which is contributed by two amino acid stretches: approximately 30 amino acids of b-dystroglycan (691-719), and approximately 15 amino acids of a-dystroglycan (550-565). Exploiting alanine scanning, we have produced a panel of site-directed mutants of our two consolidated recombinant peptides beta-dystroglycan (654-750), corresponding to the ectodomain of beta-dystroglycan, and alpha-dystroglycan (485-630), spanning the C-terminal domain of alpha-dystroglycan. By solid-phase binding assays and surface plasmon resonance, we have determined the binding affinities of mutated peptides in comparison to those of wildtype alpha-dystroglycan and beta-dystroglycan, and shown the crucial role of two beta-dystroglycan phenylalanines, namely Phe692 and Phe718, for the alpha-beta interaction. Substitution of the a-dystroglycan residues Trp551, Phe554 and Asn555 by Ala does not affect the interaction between dystroglycan subunits in vitro. As a preliminary analysis of the possible effects of the aforementioned mutations in vivo, detection through immunofluorescence and western blot of the two dystroglycan subunits was pursued in dystroglycan- transfected 293-Ebna cells.

alpha-Dystroglycan (alpha-DG) was identified as a common receptor for lymphocytic choriomeningitis virus (LCMW) and several other arenaviruses including the human pathogenic Lassa fever virus. Initial work postulated that interactions between arenavirus glycoproteins and alpha-DG are based on protein-protein interactions. We found, however, that susceptibility toward LCMV infection differed in various cell lines despite them expressing comparable levels of DG, suggesting that posttranslational modifications of alpha-DG would be involved in viral receptor function. Here, we demonstrate that glycosylation of alpha-DG, and in particular, 0 mannosylation, which is a rare type of O-linked glycosylation in mammals, is essential for LCMV receptor function. Cells that are defective in components of the O-mannosylation pathway showed strikingly reduced LCMV infectibility. As defective O mannosylation is associated with severe clinical symptoms in mammals such as congenital muscular dystrophies, it is likely that LCMV and potentially other arenaviruses may have selected this conserved and crucial posttranslational modification as the primary target structure for cell entry and infection.