Self-consistent Green function approach for calculations of electronic structure in transition metals

We present an approach for self-consistent calculations of the many-body Green function in transition metals. The distinguishing feature of our approach is the use of the one-site approximation and the self-consistent quasiparticle wave function basis set, obtained from the solution of the Schrodinger equation with a nonlocal potential. We analyze several sets of skeleton diagrams as generating functionals for the Green function self-energy, including GW and fluctuating exchange sets. Their relative contribution to the electronic structure in 3d-metals was identified. Calculations for Fe and Ni revealed stronger energy dependence of the effective interaction and self-energy of the d-electrons near the Fermi level compared to s and p electron states. Reasonable agreement with experimental results is obtained

First principle theory of correlated transport through nano-junctions

We report the inclusion of electron-electron correlation in the calculation of transport properties within an ab initio scheme. A key step is the reformulation of Landauer's approach in terms of an effective transmittance for the interacting electron system. We apply this framework to analyze the effect of short range interactions on Pt atomic wires and discuss the coherent and incoherent correction to the mean-field approach.Comment: 5 pages, 3 figure

Validity of the scaling functional approach for polymer interfaces as a variational theory

We discuss the soundness of the scaling functional (SF) approach proposed by Aubouy Guiselin and Raphael (Macromolecules 29, 7261 (1996)) to describe polymeric interfaces. In particular, we demonstrate that this approach is a variational theory. We emphasis the role of SF theory as an important link between ground-state theories suitable to describe adsorbed layers, and "classical" theories for polymer brushes.Comment: 8 pages, 1 figure, to be published in Phys. Rev.

Economic sustainability of pig slaughtering firms in the production chain of denomination of origin hams in italy

Pork meat in Italy is one of the largest agri-food chains in Italy. In the swine production chain, slaughter plays an important role, because it has an impact on animal welfare, food safety and the sustainability of the agri-food chain. These companies also deal with pigs destined for typical Denomination of Origin products and therefore play an important role in the production chain of typical products and in the field of EU agricultural policy. In this context, the research aims to analyze the economic sustainability of the major pig slaughter firms in Italy, through data analysis of the annual account statement (AAS) on a sample of eight companies analyzed over a ten-year historical series. Financial ratios and margins (FRM) analysis is applied in the research. FRM analysis shows that firms have the largest absorption of financial resources in the net working capital cycle. The research highlights the high incidence of raw materials in companies in the sector. Consequently, the profit margins of the companies in the sample are modest and in some cases are lower than the cost of debt, suggesting a moderate capacity to attract capital. This result appears as a negative signal of the economic sustainability of the companies in the sector. The research, now limited to a small number of large companies, opens a line of research that can be developed by expanding the sample to small and medium-sized enterprises of the chain of Denomination of Origin hams in Italy to suggest improvement interventions, in particular for rural or marginal areas of production

Variational approach for electrolyte solutions: from dielectric interfaces to charged nanopores

A variational theory is developed to study electrolyte solutions, composed of interacting point-like ions in a solvent, in the presence of dielectric discontinuities and charges at the boundaries. Three important and non-linear electrostatic effects induced by these interfaces are taken into account: surface charge induced electrostatic field, solvation energies due to the ionic cloud, and image charge repulsion. Our variational equations thus go beyond the mean-field theory. The influence of salt concentration, ion valency, dielectric jumps, and surface charge is studied in two geometries. i) A single neutral air-water interface with an asymmetric electrolyte. A charge separation and thus an electrostatic field gets established due to the different image charge repulsions for coions and counterions. Both charge distributions and surface tension are computed and compared to previous approximate calculations. For symmetric electrolyte solutions close to a charged surface, two zones are characterized. In the first one, with size proportional to the logarithm of the coupling parameter, strong image forces impose a total ion exclusion, while in the second zone the mean-field approach applies. ii) A symmetric electrolyte confined between two dielectric interfaces as a simple model of ion rejection from nanopores. The competition between image charge repulsion and attraction of counterions by the membrane charge is studied. For small surface charge, the counterion partition coefficient decreases with increasing pore size up to a critical pore size, contrary to neutral membranes. For larger pore sizes, the whole system behaves like a neutral pore. The prediction of the variational method is also compared with MC simulations and a good agreement is observed.Comment: This version is accepted for publication in Phys. Rev. E

Probing DNA conformational changes with high temporal resolution by Tethered Particle Motion

The Tethered Particle Motion (TPM) technique informs about conformational changes of DNA molecules, e.g. upon looping or interaction with proteins, by tracking the Brownian motion of a particle probe tethered to a surface by a single DNA molecule and detecting changes of its amplitude of movement. We discuss in this context the time resolution of TPM, which strongly depends on the particle-DNA complex relaxation time, i.e. the characteristic time it takes to explore its configuration space by diffusion. By comparing theory, simulations and experiments, we propose a calibration of TPM at the dynamical level: we analyze how the relaxation time grows with both DNA contour length (from 401 to 2080 base pairs) and particle radius (from 20 to 150~nm). Notably we demonstrate that, for a particle of radius 20~nm or less, the hydrodynamic friction induced by the particle and the surface does not significantly slow down the DNA. This enables us to determine the optimal time resolution of TPM in distinct experimental contexts which can be as short as 20~ms.Comment: Improved version, to appear in Physical Biology. 10 pages + 10 pages of supporting materia

OpenAIRE guidelines for CRIS managers: supporting interoperability of open research information through established standards

OpenAIRE is the European infrastructure enabling researchers to comply with the European Union requirements for Open Access to research results. OpenAIRE collects metadata from data sources across Europe and beyond and defines interoperability guidelines to assist providers in exposing their information in a way that is compatible with OpenAIRE. This contribution focuses on a specific type of data source, CRIS systems, and the respective OpenAIRE guidelines, based on CERIF XML. A range of issues, spanning different aspects of information representation and exchange, needed to be addressed by the guidelines in order to define a complete solution for interoperability

Raman signatures of classical and quantum phases in coupled dots: A theoretical prediction

We study electron molecules in realistic vertically coupled quantum dots in a strong magnetic field. Computing the energy spectrum, pair correlation functions, and dynamical form factor as a function of inter-dot coupling via diagonalization of the many-body Hamiltonian, we identify structural transitions between different phases, some of which do not have a classical counterpart. The calculated Raman cross section shows how such phases can be experimentally singled out.Comment: 9 pages, 2 postscript figures, 1 colour postscript figure, Latex 2e, Europhysics Letters style and epsfig macros. Submitted to Europhysics Letter

Cadmium and other hazardous elements in phosphatic fertilizers in conformity to the new European Regulation 2019/1009

The current European Fertilizers Regulation EC n. 2003/2003 does not include any direction for the content in cadmium [1]. On 25 June 2019, the new EU Fertilizing Products and Amending Regulation (EU-FPR) 2019/1009 was promulgated by the European Parliament and the Council, fixing an initial and temporary limit for Cd content in inorganic macronutrient fertilizer to 60 mgCd ∙ kgP2O5-1 [2]. The new European limit for Cd would be the most stringent in the world and only 15% of the phosphorite deposits currently exploited exhibits a low cadmium content complying with the new standard once processed to fertilizer. Since there are no substitutes for phosphate rock in phosphatic fertilizer production [3,4], the outcome of the new standard application would make unsustainable the supply of phosphatic fertilizers. This will result in a short-term measure that goes beyond the long-term sustainability objective of the proposal. In addition, the new standard will inevitably and disproportionately penalise some producers, mainly from developing countries in North Africa. It is therefore important to investigate for Cd and other hazardous elements content in fertilizers used for food production. The present research has analysed a total of 41 samples of fertilizers both for hobby and professional use obtained from the Italian market. Producers of Western and Middle Eastern Europe use the same phosphorite deposits to obtain fertilizers, thus the results of this investigation can be extended to the whole area. Obtained samples were initially pulverized in a ball mill and subjected to acid digestion in a microwave oven. Different acid digestion methods (HNO3 - HF - aqua regia - H2O2) were developed and tested for processing phosphate rock, inorganic and organo-mineral fertilizers to optimize the dissolution of different matrices. Standard reference materials, NIST SRM-695 (NPK fertilizer) and BCR-032 (Morocco phosphate rock) were processed using the same methods. Elemental analyses were performed in ICP-OES (Na, Mg, Al, Si, P, S, K, Ca, Fe, Se, Hg) and ICP-MS (Li, Be, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Sr, Cd, Sn, Sb, Ba, Tl, Pb, Bi, U). The first results showed very low Cd concentrations in hobby products. This commercial sector is known to import low-cost phosphate rock from Russia or Cola Peninsula, with a lower nutrient quality, but also a lower Cd content in comparison with professional products. Uranium content was found in relatively high concentrations and a radioactivity study has been considered as a logical extension of this research. The next analysis of more samples collected in spring will account for different fertilizer types used in distinct agricultural phases. [1] European Union. Off. J. Eur. Union. 2003, EUR-Lex - 32003R2003. [2] European Union. Off. J. Eur. Union. 2019, EUR-Lex - 32019R1009. [3] Mar, S.S., Okazaki, M. Microchem. J. 2012, 104, 17–21. [4] Ulrich, A.E. Sci. Total Environ. 2019, 650(1), 541–545

Long-term trends of PM10-bound arsenic, cadmium, nickel, and lead across the Veneto region (NE Italy)

Since the mid-90s, the European Community has adopted increasingly stringent air quality standards. Consequently, air quality has generally improved across Europe. However, current EU standards are still breached in some European hotspots. The Veneto region (NE Italy) lies in the eastern part of the Po Valley, a major European hotspot for air pollution, where EU standards for particulate matter, nitrogen oxides and ozone are still breached at some sites. This study aims to analyse the PM10-bound arsenic, cadmium, nickel, and lead concentrations over a 10 years-long period (2010-2020) in the Veneto Region by using data collected by the local environmental protection agency (ARPAV) in 20 sampling stations mostly distributed across the plain areas of the region and categorized as rural (RUR), urban (URB), and suburban (SUB) background, industrial (IND) and traffic (TRA) hotspots (Figure 1). The comprehensive dataset discussed in this study was statistically investigated to detect the seasonal trends, their relationship with other air pollutants and meteorological parameters and their spatial variations at a regional scale. This study completes previous air quality studies over the Veneto region for gaseous pollutants and bulk PM10 (Masiol et al. 2017). Samplings were carried out according to CEN EN 12341:1998 standard on quartz fibre filters and were continuous for 24 h, starting at midnight. The gravimetric determination of PM10 mass was measured following the CEN EN 12341:2014 standard. The elemental analysis was performed using an ICP-MS (Agilent 7700) after acid digestion (EN 14902:2005). The trends were analysed using different approaches on the monthly-averaged data. The shape of trends and their seasonal variations were assessed through the seasonal-trend decomposition time series procedure based on “Loess” (STL). The linear trends were computed by the Mann-Kendall trend test (p < 0.05) and the Theil-Sen nonparametric estimator of slope (MK-TS). Since this latter analysis assumes monotonic linear trends and does not consider the shape of trends, the presence of possible breakpoints was investigated using the piecewise regression. Generally, monthly patterns of all analysed elements show higher concentrations during winter, following PM10 concentrations. Some exceptions were detected and discussed. Results of trend analysis indicate statistically significant negative (decreasing) or null linear trends in almost all stations. A few positive (increasing) but not statistically significant trends were also detected. Some sites showed rapid decreases occurred in short periods and linked to peculiar events or local causes. Among others, several sites across the Venice area showed significant drops of arsenic concentrations after the REACH (Registration Evaluation Authorisation of Chemicals) implementation (Formenton et al., 2021). Data used in this study are provided by ARPAV (Agenzia Regionale per la Prevenzione e Protezione Ambientale del Veneto, https://www.arpa.veneto.it/)