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Raffaele Pastore, Ph.D.

Assistant Professor (RTD-A)
Università degli Studi di Napoli Federico II



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News and Highlights

10/5/2019
We are organizing a course at Ettore Majorana Foundation
"Polymers and Soft Materials: Glasses, Gels and Networks"
Erice, 9 – 16 July 2019
Have a look at the Flyer and at the course Website .
Interested students should contact me asap!


28/3/2019
Concentrated suspensions of Brownian beads in water:
dynamic heterogeneities trough a simple experimental technique

R. Pastore, M. Caggioni, D. Larobina, L. Santamaria Amato and F. Greco

just accepted
in the Special Topic on Water Science of
SCIENCE CHINA Physics, Mechanics & Astronomy
ArXiv



7/12/2018
Our paper just accepted in PCCP
Influence of wall heterogeneity on nanoscopically confined polymers
R. Pastore, A. David, M. Casalegno, F. Greco and G. Raos





12/11/2018


9/7/2018
I was pleased to participate in the Erice summer-school "Water and water systems: the hydrophobic effect" and give a lecture on
"Intermittent and heterogeneous dynamics in soft glassy materials".




Have a look at the slides.


3/7/2018
Awarded Best young researcher article prize 2017 by CNR-SPIN
for my paper
Cage Size and Jump Precursors in Glass-Forming Liquids



11/6/2018
Our paper in collaboration with researchers at
Stazione Zoologica A. Dohrn and Lund University,
Distinctive diffusive properties of swimming planktonic
copepods in different environmental conditions

R. Pastore, M. Uttieri, G. Bianco, M. Ribera d'Alcalá and M. G. Mazzocchi


now in BiorXiv


29/5/2018
Talk in Primosten (Croatia)
EUSMI/SoftComp Annual Meeting 2018
"Intermittent and heterogeneous dynamics in soft glassy materials: experiment and simulations"



20/4/2018
Talk in Sorrento at AERC2018
Annual European Rheology Conference
"Dense vesicle suspensions: relaxation processes and dynamic heterogeneities"



7/2/2018
Talk in Lisbon (Portugal)
Flowing Matter 2018 (organized by Cost Action MP1305)
"Cage Size and Jump Precursors in Glass-Forming Liquids: Experiment and Simulations"



2/1/18
Effects of Chemically Heterogeneous Nanoparticles on Polymer Dynamics: Insights from Molecular Dynamics Simulations
Zijian Zheng, Fanzhu Li, Jun Liu, Raffaele Pastore, Guido Raos, Youping Wu and Liqun Zhang



just accepted in Soft Matter



18/12/17
I just joined DICMaPI at the University of Naples Federico II as Assistant Professor (RTD-A)



NOVEMBER 2017 - JANUARY 2018
Visiting Scientist at
Dip. di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Politecnico di Milano
and at
Dip. di Biotecnologie Mediche e Medicina Traslazionale, Università di Milano



12/9/2017
Our paper on organic photovoltaic is in the JPCC most read article list

AudioSlides are now available online. Have a look!



31/7/2017
Our paper on organic solar cells is finally out!
Origin of Charge Separation at Organic Photovoltaic Heterojunctions:
A Mesoscale Quantum Mechanical View

M. Casalegno, R. Pastore, J. Idé, R. Po and G. Raos



open access in The Journal of Physical Chemistry C



8/6/2017
Many facets of intermittent dynamics in colloidal and molecular glasses
R. Pastore, G. Pesce, A. Sasso and M. Pica Ciamarra



just accepted in Colloids and Surfaces A



7/6/2017
Seminar:
“Endocyticic reawakening of motility and flocking in jammed epithelia”
by my guest Prof. Roberto Cerbino (University of Milan)



25/5/2017
Talk in Napoli
Fluids and Structures: Interaction and Modeling (organized by Cost Action MP1305)
" Structural relaxation and dynamic heterogeneities in soft materials: a simple experimental approach"



5/5/2017
Press relase on DVA by the University of Cincinnati



26/4/2017
We are happy to announce the press release on DVA by CNR



Read this news in "Le Scienze"

Read the english version of the press release



20/4/2017
Seminar:
"Criticality and avalanches at the yelding transition of amorphous solids under deformation"
by my guest Dr. Ezequiel Ferrero (University of Milan)


Read Abstract



24/3/2017
News on DVA in the University of Naples web-site (in Italian)






17/3/2017
Cage Size and Jump Precursors in Glass-Forming Liquids: Experiment and Simulations
R. Pastore, G. Pesce, A. Sasso and M. Pica Ciamarra



just accepted in The Journal of Physical Chemistry Letters



14/3/2017
Differential Variance Analysis: a direct method to quantify and visualize dynamic heterogeneities
R. Pastore, G. Pesce and M. Caggioni



just published in Nature Scientific Reports
DVA dedicated page




23/12/2016
Relaxation functions and dynamical heterogeneities in a model of chemical gel interfering with glass transition
A. de Candia, A. Fierro, R. Pastore, M. Pica Ciamarra and A. Coniglio



just accepted in EPJ ST
Freely available view-only version




24/11/2016
Invited talk at Ph.D. Complex Fluids School@Unina
organized by University of Naples Federico II and P&G
"Dynamic heterogeneities in complex fluids: a simple experimental approach"



5/9/2016
Talk in Rome at the
30th Conference of the European Colloid and Interface Society
(ECIS), Rome, Sept 4-9, 2016

"Many facets of intermittent dynamics in colloidal and molecular glasses"



11/7/2016
Cluster structure and dynamics in gels and glasses
R. Pastore, A. de Candia, A. Fierro, M. Pica Ciamarra and A. Coniglio



just published in JSTAT (arXiv preprint)




7/6/2016
Talk at Harvard University
90th ACS Colloid & Surface Science Symposium, June 5-8, 2016
"Many facets of intermittent dynamics in colloidal and molecular glasses"



15/4/2016
SPIN SEED 2014
Charge separation and charge transport in hybrid solar cells
PI: R. Pastore
Report Abstract



We are investigating electronic properties of organic/hybrid heterojunctions for photovoltaic applications. In collaboration with the Raos group (Politecnico di Milano), who introduced a novel quantum chemical model (JCTC 2013), we show that this method is able to simulate systems much larger than allowed by any other quantum chemical approach (see Fig.). This leads to investigate the charge delocalization and the exciton separation over the full length-scale relevant to these processes. In addition, we are performing Monte Carlo and Molecular Dynamics simulations to investigate how the morphological and dynamical properties of the active layer affect the macroscopic charge transport.


6/4/2016
Cage-jump motion reveals universal dynamics and non-universal
structural features in glass forming liquids

R. Pastore, A. Coniglio, A. de Candia, A. Fierro and M. Pica Ciamarra



just accepted in JSTAT (arXiv preprint)




February-August 2016
visiting @ University of Cincinnati and Procter&Gamble Co.







9/10/2015
Review article
Particle jumps in structural glasses
M. Pica Ciamarra, R. Pastore and A. Coniglio



Soft Matter (2015), DOI: 10.1039/C5SM01568E .

Particles in structural glasses rattle around temporary equilibrium positions, that seldom change through a process which is much faster than the relaxation time, known as particle jump. Since the relaxation of the system is due to the accumulation of many such jumps, it could be possible to connect the single particle short time motion to the macroscopic relaxation by understanding the features of the jump dynamics. Here we review recent results in this research direction, clarifying the features of particle jumps that have been understood and those that are still under investigation, and examining the role of particle jumps in different theories of the glass transition.






October 2015
visiting @ NTU Singapore







13/8/2015
Glassy dynamics of a polymer monolayer on a
heterogeneous disordered substrate

R. Pastore and G. Raos




Soft Matter (2015), DOI: 10.1039/C5SM01440A (Open Access).

We present molecular dynamics simulations of a polymer monolayer on randomly functionalized surfaces that are characterized by different fractions of weakly and strongly attractive sites. We show that the dynamics slow-down upon cooling resembles that of a strong glass-forming liquid. Indeed, the mean-square displacements show an increasingly lasting subdiffusive behaviour before the diffusive regime, with signs of Fickian yet not Gaussian diffusion, and the dynamic correlation functions exhibit a stretched exponential decay. The glassy dynamics of this relatively dilute system is dominated by the interaction of the polymer with the substrate and becomes more marked when the substrate composition is heterogeneous. Accordingly, the estimated glass transition temperature shows a non-monotic dependence on surface composition, in agreement with previous results for the activation energy and with an analysis of the potential energy landscape experienced by the polymer beads. Our findings are relevant to the description of polymer-surface adhesion and friction and the development of polymer nanocomposites with tailored structural and mechanical properties.







31/7/2015
Spatial correlations of elementary relaxation
events in glass-forming liquids

R. Pastore, A. Coniglio, and M. Pica Ciamarra



Soft Matter (2015), DOI: 10.1039/C5SM01510C .

The dynamical facilitation scenario, by which localized relaxation events promote nearby relaxation events in an avalanche process, has been suggested as the key mechanism connecting the microscopic and the macroscopic dynamics of structural glasses. Here we investigate the statistical features of this process via numerical simulations of a model structural glass. First we show that the relaxation dynamics of the system occurs through particle jumps that are irreversible, and that cannot be decomposed in smaller irreversible events. Then we show that each jump does actually trigger an avalanche. The characteristics of this avalanche change upon cooling, suggesting that the relaxation dynamics crossovers from a noise dominated regime, where jumps do not trigger other relaxation events, to a regime dominated by the facilitation process, where a jump triggers more relaxation events.





21-23/7/2015
CECAM Workshop: The Role of Structure in Dynamical Arrest
Mainz (Germany)
My Talk




12/7/2015



Scientific Reports 5, 11770 (2015)






15/6/2015
Seminar:
"Quantum chemical models of organic photovoltaic
materials for relatively large systems"
Prof. Guido Raos (Politecnico di Milano)
Read Abstract



4/6/2015
Seminar:
"On the nature of the glass crossover"
Dr. Tommaso Rizzo (CNR-ISC, Roma)
Read Abstract



22-25/3/2015
XIV International Workshop on Complex Systems
Fai della Paganella (Italy)
My Talk




17/12/2014
Dynamical phase coexistence in glass-forming liquids
R. Pastore, A. Coniglio, and M. Pica Ciamarra



One of the most controversial hypotheses for explaining the heterogeneous dynamics of molecular and colloidal glasses postulates the temporary coexistence of two phases, characterized by a high and by a low value of the diffusion coefficient. In this scenario, two phases with different diffusivities coexist for a time of the order of the relaxation time, and mix afterwards. Unfortunately, it is difficult to measure the single particle diffusion coefficient to test this hypothesis. Indeed, although the not-Gaussian shape of the van Hove distribution suggests the transient existence of a distribution of diffusion coefficients, it is not possible to infer from this quantity whereas two or more dynamical phases coexist. Here we provide the first direct observation of the dynamical coexistence of two phases with different diffusion coefficients, by showing that in the deeply supercooled regime the distribution of the single particle diffusion coefficients acquires a transient bimodal shape. We relate this distribution to the heterogeneity of the dynamics and to the breakdown of the Stokes-Einstein relation. Our work offers a basis for rationalizing the dynamics of supercooled liquids, and for relating their structural and dynamical properties.
ArXiv:1412.5304 .






21/11/2014
Connecting short and long time dynamics
in hard-sphere-like colloidal glasses

R. Pastore, M. Pica Ciamarra, G. Pesce and A. Sasso



Soft Matter 11, 622 (2015)

Glass-forming materials are characterized by an intermittent motion at the microscopic scale. Particles spend most of their time rattling within the cages formed by their neighbors, and seldom jump to a different cage. In molecular glass formers the temperature dependence of jump features, such as the average caging time and the typical jump length, characterize the relaxation processes and allow for a short-time prediction of the diffusivity. Here we experimentally investigate the cage-jump motion of a two-dimensional hard-sphere-like colloidal suspension, where the volume fraction is the relevant parameter controlling the slow down of the dynamics. We characterize the volume fraction dependence of the cage-jump features and show that, as in molecular system, they allow for a short time prediction of the diffusivity.
Soft Matter 11, 622 (2015)






24/10/2014
Awarded SEED 2014 Grant

Charge separation and charge transport in hybrid solar cells

PI: Raffaele Pastore.

Co-Investigators: Dr. A. Bruno (ENEA); Dr. G. Cantele (CNR-SPIN); Prof. D. Ninno (U. of Naples); Dr. A. de Candia (U. of Naples); Dr. A. Fierro (CNR-SPIN); Dr. G. De Filippis (U. of Naples); Prof. M. Pica Ciamarra (Nanyang Technological University, Singapore).






25/9/2014
Experiments on hard-sphere-like colloidal glasses



We connect the intermittent single particle motion and the macroscopic dynamics in colloidal suspensions at increasing volume fraction.
(With M. Pica Ciamarra, G. Pesce and A. Sasso)





21/5/2014
From cage-jump motion to macroscopic diffusion
in supercooled liquids

R. Pastore, A. Coniglio, and M. Pica Ciamarra



Soft Matter 10, 5724 (2014) .

The evaluation of the long term stability of a material requires the estimation of its long-time dynamics. For amorphous materials such as structural glasses, it has proven difficult to predict the long-time dynamics starting from static measurements. Here we consider how long one needs to monitor the dynamics of a structural glass to predict its long-time features. We present a detailed characterization of the statistical features of the single-particle intermittent motion of structural glasses, and show that single- particle jumps are the irreversible events leading to the relaxation of the system. This allows to evaluate the diffusion constant on the time-scale of the jump duration, which is small and temperature independent, i.e. well before the system enters the diffusive regime. The prediction is obtained by analyzing the particle trajectories via a parameter-free algorithm.















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