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Orsi Group: Research Topics

Lipids, membranes, proteins, water

We develop and apply the ELBA coarse-grained model, and we are also interested in atomistic and continuum models.

ELBA molecular models (left), self-assembly of DOPC lamellar phase (center), lamellar -> hexagonal phase transition of DOPE system (right).

The ELBA water model (image above) consists of a permanent electrical dipole affixed to the center of a soft sphere. More technically, the ELBA water model is an original shifted-force version (and accompanying parameters in real units) of the well-known Stockmayer potential (a model of idealized polar fluids expressed in reduced units).

The accuracy with which the ELBA model reproduces vapor-liquid equilibria (left) and the surface tension (right) is comparatively very high.

The video shows a water-vapor interface modeled with ELBA during 50 ps of molecular dynamics. An increasingly higher rate of evaporation was induced by gradually bringing the system from room to critical temperature over the course of the simulation.

The ELBA water model is currently being exploited to solvate molecules described with standard atomistic models.

Dual-resolution scheme: a protein modeled with the CHARMM force field is solvated by ELBA water.

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Permeation processes, membrane interactions with various molecules (small organic compounds, drugs, hormones, antibiotics)

Transmembrane permeation of benzene (left), alprenolol (centre), and progesterone (right).

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Proteins

Microtubule & tubulin monomers (left), alpha-actinin domains (right).

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Full details available in our publications.


Research areas under development

Nanomembranes for water filtration

Nanometre-thick membranes, typically made of polymeric material, carbon nanotubes, or graphene, can impact on crucial technological areas, for example as filters for water desalination. Molecular models of nanomembranes will be developed and simulated, a specific aim being the investigation of permeability phenomena, which are notoriously difficult to characterise by conventional experiments. In particular, it will be possible to employ rigorous computational methods ("free energy" methods) which allow various aspects of the permeation process to be elucidated quantitatively. Additionally, we are interested in fouling processes, which are regarded as one of the foremost problems to solve in this area.

Polymers

Preliminary work is being conducted to simulate polymeric material, especially elastomers. Computational predictions are intended to accompany the well-established experimental research carried out in the School.


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