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Dangelo P.,University of Rome La Sapienza | Zitolo A.,University of Rome La Sapienza | Migliorati V.,University of Rome La Sapienza | Chillemi G.,Inter University Consortium for Supercomputing in Research | And 6 more authors.
Inorganic Chemistry | Year: 2011

A new set of ionic radii in aqueous solution has been derived for lanthanoid(III) cations starting from a very accurate experimental determination of the ion-water distances obtained from extended X-ray absorption fine structure (EXAFS) data. At variance with previous results, a very regular trend has been obtained, as expected for this series of elements. A general procedure to compute ionic radii in solution by combining the EXAFS technique and molecular dynamics (MD) structural data has been developed. This method can be applied to other ions allowing one to determine ionic radii in solution with an accuracy comparable to that of the Shannon crystal ionic radii. © 2011 American Chemical Society. Source


Migliorati V.,University of Rome La Sapienza | Chillemi G.,Inter University Consortium for Supercomputing in Research | Dangelo P.,University of Rome La Sapienza
Inorganic Chemistry | Year: 2011

The solvation properties of the Zn2+ ion in methanol solution have been investigated using a combined approach based on molecular dynamics (MD) simulations and extended X-ray absorption fine structure (EXAFS) experimental results. The quantum mechanical potential energy surface for the interaction of the Zn2+ ion with a methanol molecule has been calculated taking into account the effect of bulk solvent by the polarizable continuum model (PCM). The effective Zn-methanol interactions have been fitted by suitable analytical potentials, and have been utilized in the MD simulation to obtain the structural properties of the solution. The reliability of the whole procedure has been assessed by comparing the theoretical structural results with the EXAFS experimental data. The structural parameters of the first solvation shells issuing from the MD simulations provide an effective complement to the EXAFS experiments. © 2011 American Chemical Society. Source


D'Angelo P.,University of Rome La Sapienza | Zitolo A.,University of Rome La Sapienza | Migliorati V.,University of Rome La Sapienza | Bodo E.,University of Rome La Sapienza | And 5 more authors.
Journal of Chemical Physics | Year: 2011

X-ray absorption spectroscopy (XAS) has been used to unveil the bromide ion local coordination structure in 1-alkyl-3-methylimidazolium bromide [C nmim]Br ionic liquids (ILs) with different alkyl chains. The XAS spectrum of 1-ethyl-3-methylimidazolium bromide has been found to be different from those of the other members of the series, from the butyl to the decyl derivatives, that have all identical XAS spectra. This result indicates that starting from 1-buthyl-3-methylimidazolium bromide the local molecular arrangement around the bromide anion is the same independently from the length of the alkyl chain, and that the imidazolium head groups in the liquid ILs with long alkyl chains assume locally the same orientation as in the [C 4mim]Br crystal. With this study we show that the XAS technique is an effective direct tool for unveiling the local structural arrangements around selected atoms in ILs. © 2011 American Institute of Physics. Source


Migliorati V.,University of Rome La Sapienza | Zitolo A.,University of Rome La Sapienza | Chillemi G.,Inter University Consortium for Supercomputing in Research | D'Angelo P.,University of Rome La Sapienza
ChemPlusChem | Year: 2012

A quantitative analysis of the X-ray absorption near-edge structure (XANES) spectra of the Zn 2+ ion in methanol and aqueous solution has been carried out starting from the microscopic description of the systems derived from molecular dynamics (MD) simulations. The different sensitivity of XANES towards the second-shell solvent molecules in the two solvents has been highlighted: in methanol solution, the Zn 2+ second solvation shell was found to provide a negligible contribution to the XANES spectrum, and it has been possible to reproduce the experimental data using a single coordination sphere in the calculation. Conversely, a reliable reproduction of the experimental spectrum of Zn 2+ in aqueous solution could be obtained only by including the second-shell water molecules in the calculation. The combination of MD and XANES was found to be essential to evaluate the contribution of the ion second solvation shell to the XANES spectra of a metal ion in organic solvents. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Giampaoli S.,Foro Italico University of Rome | Chillemi G.,Inter University Consortium for Supercomputing in Research | Valeriani F.,Foro Italico University of Rome | Lazzaro D.,Foro Italico University of Rome | And 6 more authors.
New Biotechnology | Year: 2013

The analysis of human genetic variability can lead to the comprehension of medical issues and to the development of personalized therapeutic protocols. Single nucleotide polymorphisms, are the most common type of human genetic variation and have been associated to disease development and phenotype forecasting. The recent technologies for DNA sequencing and bioinformatic analysis are now giving the opportunity to develop new diagnostic and prevention approaches also through health promotion protocols. The genetic data management is at the same time underlining technical limitations and old ethical issues. © 2012 Elsevier B.V. Source

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