Soil contamination evaluation by Enrichment Factor (EF) and Geoaccumulation Index (Igeo)

Heavy metals are natural constituents of soils and their concentration varies depending on parental materials. The soils were formed by. In the last years, the content of heavy metal in soils has increased due to human activities as: distribution of fertilizers, pesticides, industries, waste disposal and air pollution. Due to these activities the life capacity of soils decreased; especially where the natural background is already high because of natural parental material richness in heavy metal. As a matter of fact it is very important to distinguish between the natural background values and anthropogenic inputs, and to understand that the background values change from area to area and with the scale of the area investigated. To evaluate the soil contamination rate different indexes like Enrichment Factor (EF) and geoaccumulation index (Igeo) can be applied. These indexes are used to assess the presence and intensity of anthropogenic contaminant deposition on surface soil

Disciplina delle crisi dell’impresa societaria, doveri degli amministratori e strumenti di pianificazione: l’esperienza italiana

In materia di diritto della crisi molti ordinamenti e fra questi quello italiano si vanno lentamente “riassestando” secondo due direttrici fondamentali: la direttrice della progressiva anticipazione, dal punto di vista temporale, di quella che può definirsi la “soglia di attenzione” per le vicende di crisi; e la direttrice della crescente rilevanza degli strumenti di pianificazione in funzione di prevenzione o di soluzione delle crisi. Per la prima direttrice, con riferimento all’ordinamento italiano, basterà ricordare l’introduzione, ad opera della legge delega n. 155 del 2017, della disciplina degli strumenti di allerta e prevenzione, che fanno perno soprattutto sui particolari doveri gravanti sugli amministratori e che dovrebbero avere ad oggetto non soltanto le situazioni di crisi in senso stretto – intesa cioè come probabilità di insolvenza – ma anche tutte le situazioni di difficoltà suscettibili di sfociare in una crisi in senso stretto. Per quanto riguarda la seconda direttrice, basterà ricordare, sempre con riferimento all’ordinamento italiano, le diverse figure introdotte dalla riforma del 2005/2007, del piano di risanamento attestato, del piano nel concordato preventivo, del programma di liquidazione nel fallimento, figure sopravvenute a quella, primigenia, dei programmi di ristrutturazione o di cessione dell’amministrazione straordinaria ed alle quali si sono successivamente aggiunte altre figure: quella del piano nelle procedure di sovraindebitamento di tipo compositivo introdotte dalla l. n. 3/2012 (una sola delle quali, peraltro, può riguardare imprese anche in forma societaria), quella del programma di risoluzione previsto dalla nuova disciplina delle crisi delle imprese bancarie ed infine quella del piano di risanamento contemplato dalla recente normativa relativa alle società a partecipazione pubblica (art. 14, comma 2, d.lgs. n. 175/2016). Il saggio dà conto, da un lato, della disciplina degli strumenti di allerta e prevenzione nel contesto delle crisi delle imprese societarie e dei correlati doveri degli amministratori e, dall’altro, della disciplina delle diverse figure pianificatorie presenti nell’ordinamento italiano. In ultimo, prendendo spunto dalla speciale disciplina dell’impresa bancaria, viene posto l’interrogativo in ordine all’opportunità di arretrare la soglia di attenzione delle situazioni di difficoltà della società sino al punto di giungere alla enucleazione di un obbligo in capo all’organo di amministrazione di predisporre adeguati assetti organizzativi che contemplino, tra l’altro, la pianificazione della gestione di una crisi dell’ente collettivo né attuale né imminente, bensì meramente ipotetica

Isotopes in hydrology and hydrogeology

The structure, status, and processes of the groundwater system, which can only be acquired through scientific research efforts, are critical aspects of water resource management. Isotope hydrology and hydrogeology is a genuinely interdisciplinary science. It developed from the application of methods evolved in physics (analytical techniques) to problems of Earth and the environmental sciences since around the 1950s. In this regard, starting from hydrogeochemical data, stable and radioactive isotope data provide essential tools in support of water resource management. The inventory of stable isotopes, which has significant implications for water resources management, has grown in recent years. Methodologies based on the use of isotopes in a full spectrum of hydrological problems encountered in water resource assessment, development, and management activities are already scientifically established and are an integral part of many water resource investigations and environmental studies. The driving force behind this Special Issue was the need to point the hydrological and water resource management societies in the direction of up-to-date research and best practices

Evidence of a new low field cross-over in the vortex critical velocity of type-II superconducting thin films

We measure current-voltage characteristics as function of magnetic field and temperature in Nb strips of different thickness and width. The instability voltage of the flux flow state related to the vortex critical velocity v* is studied and compared with the Larkin-Ovchinnikov theory. Beside the usual power-law dependence v* ~ B^-1/2, in the low field range a new cross-over field, Bcr1, is observed below which v* decreases by further lowering the external magnetic field B. We ascribe this unexpected cross-over to vortex channeling due to a fan-like penetration of the applied magnetic field as confirmed by magneto-optic imaging. The observation of Bcr1 becomes a direct evidence of a general feature in type-II superconducting films at low fields, that is a channel-like vortex motion induced by the inhomogeneous magnetic state caused by the relatively strong pinning

Competition between intrinsic and extrinsic effects in the quenching of the superconducting state in FeSeTe thin films

We report the first experimental observation of the quenching of the superconducting state in current-voltage characteristics of an iron-based superconductor, namely, in FeSeTe thin films. Based on available theoretical models, our analysis suggests the presence of an intrinsic flux-flow electronic instability along with non-negligible extrinsic thermal effects. The coexistence and competition of these two mechanisms classify the observed instability as halfway between those of low-temperature and of high-temperature superconductors, where thermal effects are respectively largely negligible or predominant.Comment: 7 pages, 5 figures, fixed typo

A note on methods with 0(H4) and 0(H6) phase lags for periodic

Two families of computational methods are discussed for the solution of second order periodic initial value problems. The first is a family with 0(H4) phase-lag which contains the recently published "Numerov made explicit" method of Chawla [2]. The second is a family with 0(H6) phase-lag and periodicity interval given by H2 Є (0,12)

Assessment of a discontinuous galerkin method for the simulation of the turbulent flow around the drivaer car model

none7noThe turbulent flow over the DrivAer fastback model is here investigated with an orderadaptive discontinuous Galerkin (DG) method. The growing need of high-fidelity flow simulations for the accurate determination of problems, e.g., vehicle aerodynamics, promoted research on models and methods to improve the computational efficiency and to bring the practice of Scale Resolving Simulations (SRS), like the large-eddy simulation (LES), to an industrial level. An appealing choice for SRS is the Implicit LES (ILES) via a high-order DG method, where the favourable numerical dissipation of the space discretization scheme plays directly the role of a subgrid-scale model. Implicit time integration and the p-adaptive algorithm reduce the computational cost allowing a high-fidelity description of the physical phenomenon with very coarse mesh and moderate number of degrees of freedom. Two different models have been considered: (i) a simplified DrivAer fastback model, without the rear-view mirrors and the wheels, and a smooth underbody; (ii) the DrivAer fastback model, without rear-view mirrors and a smooth underbody. The predicted results have been compared with experimental data and CFD reference results, showing a good agreement.openColombo A.; Bortoli A.; Conti P.; Crivellini A.; Ghidoni A.; Nigro A.; Noventa G.Colombo, A.; Bortoli, A.; Conti, P.; Crivellini, A.; Ghidoni, A.; Nigro, A.; Noventa, G

Strontium Isotope as Tracers of Groundwater Contamination

Groundwater flowing under a municipal solid waste landfill has been studied to identify potential contamination phenomenon and to test strontium isotopic composition as a natural tracer of contamination. The study was carried on in June 2014 in central Italy. Five selected boreholes were selected and analysed according to their location related to the site. Samples taken from boreholes placed upward to the site were considered as uncontaminated groundwater. One borehole located downward from the site and with major contaminant values has been considered as potentially contaminated end-member. Sr isotope results show that samples located upward from the site present lower Sr concentration and highest Sr isotopic values, which reflects weathered bedrock, while borehole located downward from the site show lowest Sr values and 87Sr/86Sr ratio, probably due to pollution by landfill leachate. The mixing calculation highlights the possible mixing phenomenon for the other samples located downward from the site