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Dive into the research topics where Giuseppe Pellicane is active.

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Featured researches published by Giuseppe Pellicane.


Journal of Physics: Condensed Matter | 2004

Theory and simulation of short-range models of globular protein solutions

Giuseppe Pellicane; Dino Costa; C. Caccamo

We report theoretical and simulation studies of phase coexistence in model globular protein solutions, based on short-range, central, pair potential representations of the interaction among macro-particles. After reviewing our previous investigations of hard-core Yukawa and generalized Lennard-Jones potentials, we report more recent results obtained within a DLVO-like description of lysozyme solutions in water and added salt. We show that a one-parameter fit of this model, based on static light scattering and self-interaction chromatography data in the dilute protein regime, yields demixing and crystallization curves in good agreement with experimental protein-rich?protein-poor and solubility envelopes. The dependence of cloud and solubility point temperatures of the model on the ionic strength is also investigated. Our findings highlight the minimal assumptions on the properties of the microscopic interaction sufficient for a satisfactory reproduction of the phase diagram topology of globular protein solutions.


Journal of Physics: Condensed Matter | 2003

Phase coexistence in a DLVO model of globular protein solutions

Giuseppe Pellicane; Dino Costa; C. Caccamo

Globular protein solutions of lysozyme in water and added salt are modelled according to the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, in order to determine their fluid–fluid and fluid–solid coexistence lines. Calculations are based on both computer simulations and theoretical approaches. Our results indicate that, when the potential parameters are obtained by fitting physical properties directly deducible from either static or dynamic light scattering data, the fluid–fluid phase coexistence predictions agree quite well with the experiments. Our description of the solid phase allows only a qualitative reproduction of the experimental solubility boundaries. The overall accuracy of our predictions is discussed in view of the well known limitations of the DLVO representation of protein solutions.


Journal of Physics: Condensed Matter | 2002

Liquid-liquid phase transition in one-component fluids

Gianpietro Malescio; Giancarlo Franzese; Giuseppe Pellicane; Anna Skibinsky; Sergey V. Buldyrev; H. Eugene Stanley

The stability of a one-component model system interacting through an isotropic potential with an attractive part and a softened core is investigated through integral equations and molecular dynamics simulation. The ‘penetrability’ of the soft core makes it possible for the system to pass from an expanded liquid structure at intermediate densities to a more compact one at high densities.


Journal of Chemical Physics | 1998

A comprehensive study of the phase diagram of symmetrical hard-core Yukawa mixtures

C. Caccamo; Dino Costa; Giuseppe Pellicane

The phase diagrams of hard-core Yukawa mixtures (HCYM), constituted of equal sized hard spheres interacting through an attractive Yukawa tail, are determined by means of Gibbs Ensemble Monte Carlo (GEMC) simulations, Semi-grand Canonical Monte Carlo (SGCMC) simulations, and through the modified hypernetted-chain (MHNC) theory. Freezing lines are obtained according to an approach recently proposed by Giaquinta and co-workers [Physica A 187, 145 (1992); Phys Rev. A 45, 6966 (1992)] in which an analysis of multiparticle contributions to the excess entropy, Δs, is performed, with the determination of the Δs=0 locus. Liquid–vapor coexistence, determined through GEMC simulations, turns out to be favored when the strength ratio ν of unlike to like particle interaction, is close to 1. For lower ν’s, liquid–vapor coexistence is favored at low densities, and liquid–liquid coexistence, determined through SGCMC simulations, at high densities. The liquid–vapor binodal shifts downward in temperature and flattens when ν...


Journal of Chemical Physics | 2002

Microscopic theories of model macromolecular fluids and fullerenes: The role of thermodynamic consistency

C. Caccamo; Giuseppe Pellicane

We investigate the accuracy of two well-known integral equation theories (IETs) of the fluid state, namely, the modified hypernetted chain (MHNC) approximation and the hybridized mean spherical approximation (HMSA), as applied to systems characterized by short-range interactions. The theoretical approaches are implemented by enforcing their thermodynamic consistency according to two different strategies: in one case the equality of the isothermal compressibility, as calculated via the virial and fluctuation routes from structure to thermodynamics, is imposed [“local” consistency (LC)]; in the other case the equality of the pressure as calculated either via the two previous routes, or via the virial and the energy routes, is imposed [“global” consistency (GC)]. We show that for the class of potentials at issue the GC is in general considerably more accurate than the LC. We document this result by investigating the performances of the MHNC and the HMSA, as applied to the calculation of the thermodynamic and...


Journal of Chemical Physics | 2003

Free energy determination of phase coexistence in model C60: A comprehensive Monte Carlo study

Dino Costa; Giuseppe Pellicane; Maria C. Abramo; C. Caccamo

The free energy of the solid and fluid phases of the Girifalco C60 model are determined through extensive Monte Carlo simulations. In this model the molecules interact through a spherical pair potential, characterized by a narrow and attractive well, adjacent to a harshly repulsive core. We have used the Widom test particle method and a mapping from an Einstein crystal in order to estimate the absolute free energy in the fluid and solid phases, respectively; we have then determined the free energy along several isotherms, and the whole phase diagram, by means of standard thermodynamic integrations. The dependence of the simulation’s results on the size of the sample is also monitored in a number of cases. We highlight how the interplay between the liquid–vapor and the liquid–solid coexistence conditions determines the existence of a narrow liquid pocket in the phase diagram, whose stability is assessed and confirmed in agreement with previous studies. In particular, the critical temperature follows closel...


Journal of Physical Chemistry B | 2012

Colloidal Model of Lysozyme Aqueous Solutions: A Computer Simulation and Theoretical Study

Giuseppe Pellicane

Lysozyme interactions in an aqueous solution are modeled via the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. We calculate the structural functions at different pH values by means of Monte Carlo computer simulation and integral equation theories. The theoretical structure factor is then used to evaluate the scattered intensities, which are compared with the experimental small-angle neutron scattering data reported in Philos. Mag.2011, 91, 2066. We find that the DLVO theory reproduces only qualitatively the tendency of protein interactions to become more short-range and attractive at low ionic strength; however, at sufficiently high ionic strength, the theory becomes quantitative. At the higher investigated pH values, DLVO theory predicts the formation of protein aggregates driven by the competition of short-range attraction and long-range repulsion.


Journal of Physical Chemistry B | 2010

Molecular Dynamics of an Embedded-Charge Model of Lysozyme Aqueous Solutions

Maria C. Abramo; C. Caccamo; Dino Costa; Giuseppe Pellicane; Romina Ruberto

The onset of liquid-vapor separation in an interaction site model of a lysozyme aqueous solution is investigated by means of molecular dynamics (MD). Calculations are performed for a soft-core version of a potential early introduced by Carlsson et al. (J. Phys. Chem. B 2001, 105, 9040; 2001, 105, 12189.) whose liquid-vapor coexistence was studied by Rosch and Errington (J. Phys. Chem. B 2007, 111, 12591.); our modified model preserves the tailoring onto the experimental lysozyme solution properties embodied by those descriptions. We first show that the structural results obtained by Carlsson et al. at ambient conditions are quite well reproduced by our approach. Then, we cool the system along an isochoric path by monitoring the structural and dynamical properties at various temperatures. We thus show that a fluid-fluid separation takes place at a temperature 15% below the presumed binodal; in particular, we observe that density inhomogeneities develop rather early in the MD run and evolve over tens of nanoseconds into two dense aggregates that eventually merge, after approximately 100 ns more, into a single liquid phase separated from a vapor region by a well-defined planar interface. The densities of the two coexisting fluids are compatible with previous determinations of the binodal line. The connections of this work to the overall scenario of phase stability investigations in protein solutions, as well as possible developments based on the use of more refined models, are discussed.


Physical Review E | 2001

Simple fluids with complex phase behavior.

Gianpietro Malescio; Giuseppe Pellicane

We find that a system of particles interacting through a simple isotropic potential with a softened core is able to exhibit a rich phase behavior including: a liquid-liquid transition in the supercooled phase, as has been suggested for water, a gas-liquid-liquid triple point, a freezing line with anomalous reentrant behavior. The essential ingredient leading to these features resides in the presence of two effective radii in the repulsive core. The potential investigated appears appropriate for a class of spherical polymeric micelles recently investigated.


Journal of Chemical Physics | 2014

Gibbs ensemble Monte Carlo of nonadditive hard-sphere mixtures

Giuseppe Pellicane; Owen D. Pandaram

In this article, we perform Gibbs ensemble Monte Carlo (GEMC) simulations of liquid-liquid phase coexistence in nonadditive hard-sphere mixtures (NAHSMs) for different size ratios and non-additivity parameters. The simulation data are used to provide a benchmark to a number of theoretical and mixed theoretical/computer simulation approaches which have been adopted in the past to study phase equilibria in NAHSMs, including the method of the zero of the Residual Multi-Particle Entropy, Integral Equation Theories (IETs), and classical Density Functional Theory (DFT). We show that while the entropic criterium is quite accurate in predicting the location of phase equilibrium curves, IETs and DFT provide at best a semi-quantitative reproduction of GEMC demixing curves.

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Lloyd L. Lee

California State University

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Franz Saija

National Research Council

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