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THEMES PROPOSED FOR THE XXX CICLE OF PhD (2015)

EXPERIMENTAL PROPOSALS
  • Title: Understanding and controlling friction.
  • Tutor: Prof. Sergio Valeri, (sergio.valeri@unimore.it) Dipartimento FIM
    Abstract: The proposed activity will face one or more of the following topics:
    • drawing bridges between friction at different scales
    • controlling tribological behavior by exploiting surface geometries
    • exploring tribological processes and phenomena in extreme operating conditions
    • understanding the adhesion and friction mechanisms of atomic or molecular aggregates on surfaces
    The experimental research will be mainly carried out at Sup&rman, a Laboratory of the Emilia-Romagna Regional High-Technology Network, hosted by FIM. The activity will be performed within an interdisciplinary context of collaborations at the regional (IntermechMoRe, Centro Interpartimentale per la Ricerca Applicata nella Meccanica Avanzata e nella Motoristica, see http://www.intermech.unimore.it/site/home.html) and international (COST Action MP1303 “Understanding and Controlling Nano and Mesoscale Friction”, see http://www.nanofriction.org/) level.

  • Title: Functionalization of materials with reducible oxides.
  • Tutor: Dr. Paola Luches, luches.paola@unimore.it, CNR-NANO-S3
    Abstract: The aim of the proposed activity is to optimize the performances and add new functionalities to materials - with application in catalysis, energy conversion and biomedicine - by the addition of reducible oxides. The experimental research will be carried out both at UNIMORE-FIM CNR-NANO laboratories and at synchrotron radiation facilities. The activity will be performed within an interdisciplinary and international context of collaborations (COST Action CM1104, see www.cost-redox.eu).

  • Title: Circuit-QED experiments with superconducting resonators and molecular spins.
  • Tutor: Dr. Alberto Ghirri alberto.ghirri@nano.cnr.it, CNR-NANO-S3, Prof. Marco Affronte Dip. FIM
    Abstract: The objective of this experimental thesis is to observe the strong-coupling between microwave electromagnetic fields and molecular spins (http://www.nano.cnr.it/index.php?mod=men&id=187 ) in a hybrid solid-state device [Rev. Mod. Phys. 85, 623 (2013), PRL 112, 120501 (2014); DOI: 10.1007/430_2014_145]. The main activity will be devoted to the fabrication and test of high Q-factor superconducting resonators and the implementation of the cryogenic set-up at 300 mK and 9 T.
    Complementary measurements of the decoherence rates of suitable molecular nanomagnets will be performed by pulsed EPR experiments at international facilities.

  • Title: Graphene based molecular spintronics.
  • Tutor: Dr. Andrea Candini andrea.candini@nano.cnr.it, CNR-NANO-S3, Prof. Marco Affronte Dip. FIM
    Abstract: Graphene has been experimentally available only recently but it is now attracting a great deal of interest in nano-electronics and beyond. The thesis work comprises the preparation and characterization of graphene based devices by using state-of-the art fabrication techniques and low temperature magneto-transport measurements. The final goal is the realization and study of hybrid devices made of graphene and molecular nanomagnets capable to read the spin state of single magnetic molecules. This activity is supported by a fellowship: MIUR FIRB Futuro in Ricerca 2013: http://bandi.urp.cnr.it/doc-assegni/documentazione/5065_DOC_EN.pdf
    Further information: http://www.nano.cnr.it/index.php?mod=men&id=189, http://www.moquas.eu/.

  • Title: MagnetoCaloric Effect in Molecular Nanomagnets.
  • Tutor: Prof. Marco Affronte marco.affronte@unimore.it, Dip. FIM
    Abstract: Molecular nanomagnets present giant Magnetocaloric Effect at cryogenic temperatures, that is record cooling power upon the application of magnetic field. Our group is leading this field Appl. Phys. Lett. 87, 072504 (2005). Polyhedron 24, 2573 (2005). J. of Mat. Chem. 16, 2534 – 2549 (2006). Phys. Rev. B 79, 104414 (2009). Dalton Trans., 2014, 43,9136, and recently showed that this properties is held at single molecule level. (Advanced Materials 25, 2816–2820 (2013), Adv. Funct.Mat doi: 10.1002/adfm.201400460 (2014)). This open the possibility to exploit this properties to fabricate cooling devices on-one-chip We proposed work deals with the fabrication and optimization of nano-coolers for specific applications and includes characterization of new molecular nanomagnets, deposition of molecular on substrate, fabrication of on-one-chip microcoolers.

  • Title: Growth and functional properties of pre-formed metal/ metal oxides core-shell nanoparticles.
  • Tutor: Prof. Sergio D’Addato
    Abstract: The interest in metal nanostructured films has grown in the last years because of their fascinating physical properties and their potentiality in various applications, like magnetic recording industry, catalysis and plasmonics. We propose a PhD thesis devoted to the investigation of metal and core-shell oxide-metal nanoparticles with a recently developed source which is able to produce and mass-select clusters1. The study will be focused on the structure, chemical and magnetic properties of the individual particles and of the nanoparticle assembled films. Some of the techniques to be used in campus will be AFM-STM, XPS, SEM, TEM and visible-UV Reflectivity. Part of the experimental activity will be also carried out in external facilities like synchrotrons (XAFS, PEEM and XMCD experiments), in collaboration with other groups.
    1S. D’Addato et al. J. Phys. Condensed Matter 23(2011)175003
    Collaborations: D. Kumar (NCAT University, North Carolina, USA), C. Binns (Leicester University, UK), A. Ponti (CNR-ISTM, Milano, Italy).
    Coworkers: V. Grillo (CNR-NANO), P. Luches (CNR-NANO)supplementary information: http://www.nano.cnr.it/index.php?mod=peo&id=78

  • Title: Two-dimensional Dirac systems: Electronic and vibrational properties of Graphene and 3D Topological insulators.
  • Tutor: Dr. Valentina De Renzi (vderenzi@unimore.it)
    Abstract: Two-dimensional electronic systems, such as graphene and 3D topological insulators (TIs), are extremely interesting from the fundamental point of view and promising materials for applications, in particular in the emerging fields of plasmonics and spintronics.
    In this thesis, the electronic and vibrational properties of 2D Dirac systems will be experimentally investigated by means of electron spectroscopies (both on-campus and at synchrotron radiation facilities) and scanning microscopies. The focus of the research will be in particular on plasmon-mode properties and phonon-electron coupling. Moreover, adsorption and intercalation of different molecular species will be investigated, aiming at a fine tuning of the system electronic properties.
    Collaborations with both experimental (UNI-Calabria, Elettra -Trieste) and theoretical groups (CNR-NANO, CSIC S. Sebastian- Spain) are envisaged;
    co-workers: Dr. A. Lodi-Rizzini, Prof. U. del Pennino, Dr. R. Biagi, Dr. V. Corradini

  • Title: Molecular Approaches to Nanoscale Magnets.
  • Tutor: Prof. Andrea CORNIA (acornia@unimore.it)
    Abstract: A current fundamental and technological goal is the design of molecular nanomagnets (MNs) exhibiting a memory effect in a manageable temperature (T) range [1]. The proposed research activity takes up the challenge of using metal-metal bonds to assemble MNs with a well-isolated high-spin state even at room T [2].
    Techniques: inorganic/organic/organometallic synthesis, mass spectrometries, XRD, magnetic measurements. [1] Rinehart et al., J. Am. Chem. Soc. 2011, 133, 14236. [2] Zhao et al., J. Am. Chem. Soc. 2011, 133, 8293.

  • Title: Thiophene-based materials for optoelectronics and sensors.
  • Tutor: Prof. Adele Mucci
    Abstract: This project is aimed at the synthesis of thiophene based oligomers and polymers. The idea is to work both on the backbone units and on the functionalization of the side chain to modulate the properties of the functional material for application in sensors, microelectronics and photovoltaic devices. At present, dithienosilole units are employed for the backbone, together with bithienyl or thienothioenyl units. The work will be carried out mainly at the organic chemistry laboratories of the DSCG Dept of Unimore.

  • Title: Folding/misfolding trajectories and energy landscapes of single protein molecules.
  • Tutor: Dr. Ciro Cecconi (ciro.cecconi@gmail.com)
    Abstract: Using optical tweezers and a well-established protocol, we propose to:
    • identify folding and misfolding trajectories and characterize the molecular rearrangements leading to native and misfolded conformations of different proteins
    • characterize the kinetics and thermodynamics of the folding and misfolding events to ultimately reconstruct the energy landscape underlying these reactions
    • study the effects of molecular crowding on misfolding probability and energy landscape
    • characterize the effect of different pathogenic mutations on misfolding reactions.


  • Title: Thermodynamics and mechanics of biological membrane model systems.
  • Tutor: Prof. Andrea Alessandrini (andrea.alessandrini@unimore.it)
    Abstract: The proposed activity will concentrate on the study of the thermodynamical and mechanical properties of model lipid bilayers. The research will consider:
    • Lipid bilayers of increasing complexity including Giant Membrane Plasma Vesicle (liposome extracted from the plasma membrane of living cells)
    • Effects of drugs on the thermodynamical and mechanical properties of lipid bilayers near to their critical points
    • Reconstitution of membrane proteins in Giant Unilamellar Vesicles to study their functional properties
    The experimental techniques which will be exploited include: Atomic Force Microscopy, Micropipette Aspiration Technique, Patch and Voltage clamp, Fluorescence (epi and confocal) microscopy.

THEORETICAL PROPOSALS
  • Title: Topological properties in periodically driven quantum systems.
  • Tutor: Prof. F. Manghi. franca.manghi@unimore.it, Dip. FIM
    Abstract: The study of this novel topological phases of is an extremely active research field. Quite interestingly it has been recently shown that non trivial topological phases may be induced by external oscillating fields. This thesis project investigates the possibility of creating new topological phases by light. The topological properties of many interacting electrons will be studied in the presence of e-e interaction (1) and of time dependent fields will be studied. Both model and realistic systems will be investigated.
    (1) Topological invariants in interacting Quantum Spin Hall: a Cluster Perturbation Theory approach F. Grandi, F. Manghi, O. Corradini, C.M. Bertoni, A. Bonini arXiv:1404.1287v2.

  • Title: New quantum perspectives for carrier and heat transport in new-generation memory devices.
  • Tutor: Prof. Rossella Brunetti rossella.brunetti@unimore.it, Dip. FIM
    Abstract: The goal of the proposed research is the formulation of an original theoretical and computational approach suitable to analyse how the electrical properties of chalcogenide memory devices are influenced by the appearance of quantum effects introduced by the reduced dimensionality of the devices. The proponent research group has a solid background in the fields of electrical transport physics and device simulations, and it has been working for about seven years on semiclassical transport properties of chalcogenide materials (see state of the art in the ppt presentation). New experimental findings on sub-nanometer structures have stimulated the analysis of possible quantum effects.

  • Title: Spin-currents and non-Abelian gauge fields in many-electron systems on the nanoscale.
  • Tutor: Dr. Stefano Pittalis, stefano.pittalis@nano.cnr.it, CNR-NANO-S3
    Abstract: The ab-initio description of magnetic phase transitions, dynamics of magnetic domain walls, energetics of non-collinear spin-density configurations, and spin-torque transfer processes in spintronic devices are all challenging problems that await proper solutions. Our goal is to tackle them within a unified and general approach: the spin-current density functional theory (SC-DFT) and its time-dependent and finite-temperature generalizations. The ideal candidate for this project has strong analytical and/or numerical skills, and an interest on application and development of novel computational methods.

  • Title: Ab-initio quantification of entanglement in many-electron systems.
  • Tutor: Dr. Stefano Pittalis, stefano.pittalis@nano.cnr.it, CNR-NANO-S3
    Abstract: The problem of quantifying the entanglement of quantum mechanical states has attracted a great deal of attention in recent years, mostly in the context of quantum information theory, where entanglement is considered a useful resource. In this project, we propose to develop novel routs to the quantification of entanglement between electrons in atoms, molecules, and extended periodic systems. Prerequisites for this project are strong analytical and/or numerical skills, and an interest on application and development of novel computational methods.

  • Title: Optoelectronic properties of transparent conductive materials for unconventional plasmonics.
  • Tutor: Dr. Arrigo Calzolari arrigo.calzolari@nano.cnr.it, CNR-NANO-S3 in collaboration with Alice Ruini and Alessandra Catellani
    Abstract: The aim of the present project is the theoretical investigation, based on first principles approaches, of the electronic, optical and plasmonic properties of novel and unconventional transparent conductive materials for plasmonic applications as metamaterials, waveguides and near-zero-epsilon systems.
    This work will be done in collaboration with national and international experimental groups.
    For further details see: http://amuse.nano.cnr.it/?page_id=233

  • Title: Thermolectric properties of low-dimensional systems for low-temperature thermoelectric generators.
  • Tutor: Dr. Arrigo Calzolari arrigo.calzolari@nano.cnr.it, CNR-NANO-S3
    Abstract: The aim of the present project is the improvement of the TE performances in low-dimensional systems, through the microscopic understanding of the mechanisms that carry the enhancement of the power factor and the reduction of the thermal conductivity, by means of first principles approaches. This work will involve both the application of state-of-the-art packages for electronic structure and transport calculations of interesting physical systems, and the development of new computational methods for the evaluation of quantum (electron and thermal) transport in nanostructures.
    For further details see: http://amuse.nano.cnr.it/?page_id=238

  • Title: Hybrid models to describe semiconductor nanowires for applications in nanophotonics and sensoring.
  • Tutor: Prof. Rita Magri, rita.magri@unimore.it, Dip FIM
    Abstract: There is a substantial lack of adequate theoretical methods for tackling the challenges posed by the simulation of the properties of nanowire structures when incorporated in complex devices, such as photovoltaic solar cells, photoelectrochemical (PEC) cells and nanosensors. In order to accurately describe the changes in the electronic structure (and the corresponding changes in the current flow or in the optical response) of complex nanowire systems, a new approach that takes advantage of the strengths of both ab-initio and semiempirical methodologies, but suffers from none of their limitations, is needed. This has become nowadays a world-wide challenge: to build a multi-scale, hybrid method able to treat complex problems where different regions of the system can be treated with different accuracy on different spatial scales. This project aims at achieving a high degree of sophistication by interfacing atomistic ab-initio approaches with atomistic empirical methods for the description of both the interconnected structural and electronic aspects of device functioning.
    Reference: M. Rosini and R. Magri, ACS nano 4,6021 (2010)
    International collaborations

  • Title: Multiscale models for the simulation of epitaxial growth of nanostructures on surfaces.
  • Tutor: Prof. Rita Magri rita.magri@unimore.it, Dip FIM
    Abstract: The aim is to study how nanostructures form on a surface and the role of surface defects in nanostructure nucleation. To tackle this complex problem a multiscale approach needs to be built where atomic processes occurring over different time and space scales get connected to give rise to the observed phenomena. Starting from ab-initio calculations based on O(N) methods it is possible to extract the relevant information to simulate the processes using coarser grain approaches such as Kinetic Monte Carlo and coupled sets of rate equations. Codes and expertise are already available and also a wealth of experimental observations on different systems that need to be understood.
    Reference: F. Arciprete, E. Placidi, R. Magri, M. Fanfoni, A. Balzarotti, and F. Patella, ACS nano 7, 3868 (2013). Collaborations with experimentalists

  • Title: Multiple Excitons Generation in Low Dimensional Systems.
  • Proposers: Prof. Stefano Ossicini, Dr. Elena Degoli, Dr. Ivan Marri
    Tutor: Prof. Stefano Ossicini stefano.ossicini@unimore.it
    Abstract: The use of low dimensional systems as constituent elements of the modern solar cell devices leads to an increase of the solar spectrum portion that can be absorbed and to the possibility to exploit non-radiative recombination mechanisms (like for instance the multiple excitons generation processes) to minimize thermalization loss mechanisms that occur when high-energy photons are absorbed. Going beyond the state of the art, we aim at developing a new ab-initio formalism in order to examine competing dynamical effects involved in the Coulomb-driven electron-hole multiple generation processes. This sort of investigation will play a fundamental role in the progress and delineation of the technological innovation in the field of the third-generation photovoltaic.
    Collaborators: Dr. Marco Govoni, University of Chicago USA, Dr Maurizia Palummo, Universitŕ Roma Tor Vergata.
    Supplementary information: http://www.nanomodelling.unimore.it/site/home.html

  • Title: Ab-initio calculation of linear and non-linear optical properties of quantum confined semiconducting materials.
  • Proposer: Dr. Elena Degoli and Dr. Stefano Ossicini
    Abstract: This thesis aim to develop new theoretical tools in order to examine second and third order nonlinear phenomena. In particular linear and nonlinear (2nd and 3rd order effects) optical properties will be investigated in quantum confined Si nanostructures (Si-ns) as nanowires and nanocrystals, both intrinsic and doped. The reliability of our approach1,2,3 wil be fundamental to both interpret and predict the properties of these nanostructured materials and to guide experiments for their potential application in both photonic and optical fiber communication technologies.
    1) Second-harmonic generation in silicon waveguides strained by silicon nitride M. Cazzanelli, Elena Degoli, E. Luppi,V. Véniard, S. Ossicini, et al. NATURE MATERIALS vol. 11, 148 (2012)
    2) Large crystal local-field effects in second-harmonic generation of a Si/CaF2 interface: An ab initio study. M. Bertocchi, E. Luppi, E. Degoli, V. Véniard, S. Ossicini PHYS. REV. B, 86, 035309 (2012).
    3) Defects and strain enhancements of second-harmonic generation in Si/Ge superlattices M. Bertocchi, E. Luppi, Elena Degoli, V. Véniard, S. Ossicini. THE JOURNAL OF CHEMICAL PHYSICS 140, 214705 (2014).

  • Title:Reactions at materials interfaces under load and shear: fundamental understanding and applications.
  • Tutor: Prof. Elisa Molinari and Dr. M. Clelia Righi
    Abstract: During the course of a chemical reaction, reactants need to overcome an energy barrier to transform into products. The energy for this process is typically provided by heat or light. A fundamentally different way of initiating or accelerating a reaction is the use of mechanical forces. Understanding reaction kinetics in the presence mechanical forces represents a fascinating fundamental problem with important applications in different fields, such as “tribochemistry”, where chemical reactions involving lubricant or environmental molecules are activated at the interface between two solids in relative motion. The present PhD thesis will focus on ab initio molecular dynamics simulations of chemical reactions involving water molecules confined within atomically-thin layers under load and shear. Multilayer graphene and molybdenum disulphide will be considered due to the growing interest in their lubricating properties, which are affected in opposite way by air humidity.

  • Title: DNA-nanoparticles interactions
  • Tutor: Dr. Stefano Corni, Dr. Rosa Di Felice
    Abstract:Interaction of DNA with inorganic surfaces and nanoparticles is relevant both in the use of DNA for biosensing (e.g., DNA chips), nanoelectronics (DNA on surface as a electronic device components), but also to understand possible biological effects of nanoparticles. The PhD project consists in developing/applying computational tools to disclose such interactions. It involves local & international collaborations. No additional scholarship available.

  • Title: Investigating mechanical unfolding of proteins by means of molecular simulations
  • Tutor: Dr. Stefano Corni, Dr. Rosa Di Felice
    Abstract: Understanding how proteins fold is a major scientific goal, with a great biomedical relevance. Mechanical (un)folding via optical tweezers joint with atomistic/coarse grained simulations are powerful tools to clarify folding. The PhD project consist in atomistically simulating (and testing/developing coarse-grained models) optical tweezers experiments. It is performed in collaboration with the exp group of C. Cecconi and international co-workers. No additional scholarship available.

  • Title: Multiscale simulations of protein-surface and protein-nanoparticle interactions
  • Proponent: Dr. Stefano Corni
    Abstract: Protein-surface & protein-nanoparticle interactions are central to several material science and bio-oriented systems. To cite just a few: enzymatic biofuel cells (electric power by organics fuels), guiding self-assembling at the nanoscale with material-specific proteins, nanoparticle effects on protein aggregation. The PhD project consists in extending the computational tools developed by our group, and/or to apply them to problems of biotechnological/material science relevance. It involves national∫ernational collaborations. No additional scholarship available.

  • Title: Developing and applying computational tools for molecular plasmonics
  • Proponent:Dr. Stefano Corni
    Abstract: Molecules close to nanoplasmonics systems are know to develop exceptional optical properties, that can be used, e.g., for sensing and photovoltaics. In addition to established plasmonic materials (such as Au, Ag), new ones are emerging such as graphene-based nanostructures. The PhD project consists in developing/applying computational/theoretical methods to understand and predict plasmonics phenomena involving molecules and both new and traditional plasmonics materials. No additional scholarship available.

  • Title: Development of advanced density-functional and manybody perturbation theory methods
  • Tutor: Prof. Elisa Molinari, Dr. Andrea Ferretti (CNR-NANO, Modena)
    Abstract:The advent of new computational architectures and paradigms in high-performance computing calls for a re-design of our computational and theoretical methods. This thesis will deal with the investigation of advanced ab initio schemes to be adopted for electronic structure simulations of condensed matter systems.
    These methods are meant to go beyond standard Kohn-Sham density functional theory, possibly along the lines of the recently proposed frequency-dependent spectral potentials [1,2].
    Diagrammatic approaches from many-body perturbation theory will also be considered, and the connection with density functional methods exploited. The analysis of self-interaction errors [3,2] will be used throughout as a benchmark tool for the proposed methods. Depending on the candidate, theory development, software implementation, and numerical validation activities will be considered.The work will be done in collaboration with the THEOS Laboratory (prof. N. Marzari) at EPFL.
    [1] M. Gatti, V. Olevano, L. Reining, I. Tokatly, Phys. Rev. Lett. 99, 057401 (2007).
    [2] A. Ferretti, I. Dabo, M. Cococcioni, N. Marzari, Phys. Rev. B 89, 195134 (2014).
    [3] I. Dabo, A. Ferretti, N. Poilvert, Y. Li, N. Marzari, M. Cococcioni, Phys. Rev. B 82, 115121 (2010).

  • Title: Quantum correlations in few-particles nanostructures
  • Tutor: Dr. Paolo Bordone (bordone@unimore.it), Dr. Andrea Bertoni (andre.bertoni@cnr.it)
    Abstract:This thesis addresses the exact quantum dynamics of few-particles systems in semiconductor nanostructures. We developed a numerical code for the time-dependent solution of the Schroedinger equation in 2D systems, suitable to investigate entanglement and interference phenomena in 2D nanostructures. In particular we intend to explore the potentialities of edge states in the QH regime for possible implementations of quantum computing devices.

  • Title: Quantum correlations in decohering systems
  • Tutor: Dr. Paolo Bordone (bordone@unimore.it)
    Abstract: This thesis focuses on the analysis of quantum correlations in simple theoretical models of few particles subject to environmental noise. Some entanglement and quantum discord criteria, commonly adopted in the analysis of bipartite systems, will be extended, by means of analytical and numerical techniques, to the case of multipartite systems. In particular the effect of both classical and quantum noisy environments will be investigated.

  • Title: Graphene nanosystems excitations: many-body effects
  • Tutor: Prof. Elisa Molinari, Dr. Deborah Prezzi, Dr. Andrea Ferretti (CNR-Nano, Modena)
    Abstract: Graphene and other quasi-two-dimensional systems are now investigated experimentally also by optical spectroscopies. Novel phenomena are expected as a consequence of many body interactions. The thesis will investigate these effects on the excitation spectra by ab-initio methods beyond DFT, and help design/interpret experiments to highlight their signatures, in close collaboration with leading European experimental groups in the field.

  • Title: Understanding charge separation in organic and hybrid photovoltaics
  • Tutor: Prof. Elisa Molinari, Dr. Alice Ruini, Dr. Deborah Prezzi (CNR-Nano, Modena)
    Abstract: Electron-hole interactions in photoexcited organic and hybrid structures are known to be very important, with exciton binding energies as large as tenths of eV. The ultrafast process leading to electron-hole separation is then controversial in many of these systems. To address this issue, the thesis will investigate the nature and spatial character of excitations by many-body perturbation theory, and compare with the results of real-time time-dependent density funtional theory and/or further simplified models accounting for electron-phonon interactions. One or more thesis are available, involving collaborations with experimental groups on polymers, blends, as well as the new family of organometal perovskite hybrids.

  • Title: Understanding ionic and molecular permeation in graphene-based multilayers
  • Tutor: Prof. Elisa Molinari, Dr. Stefano Corni (CNR-Nano, Modena)
    Abstract: Recent experiments by leading experimental teams in Europe show that graphene and graphene oxide multilayers can work as effective ionic or molecular filters. In spite of the huge technological interest, the microscopic origin of the the ultrafast permeation mechanisms is still unclear. The thesis will use statistical mechanics approaches to treat the complexity of structures and processes, and combine them with molecular dynamics tools that can account for relevant local atomistic properties. The work will be co-supervised with Alberto Petri (CNR-Ist Sist Complessi, Roma).