Biomedical subjects

E Granato

Publications and source records attributed to E Granato.

At least 19 recordsLinked to original sources

PubMed2006

Phase diagram and commensurate-incommensurate transitions in the phase field crystal model with an external pinning potential.

We study the phase diagram and the commensurate-incommensurate transitions in a phase field model of a two-dimensional crystal lattice in the presence of an external pinning potential. The model allows for both elastic and plastic deformations and provides a continuum description of lattice systems, such as for adsorbed atomic layers or two-dimensional vortex lattices. Analytically, a mode expansion analysis is used to determine the ground states and the commensurate-incommensurate transitions in the model as a function of the strength of the pinning potential and the lattice mismatch parameter. Numerical minimization of the corresponding free energy shows reasonable agreement with the analytical predictions and provides details on the topological defects in the transition region. We find that for small mismatch the transition is of first order, and it remains so for the largest values of mismatch studied here. Our results are consistent with results of simulations for atomistic models of adsorbed overlayers.

Journal Article↗

PubMed2005

Strain relief in Cu-Pd heteroepitaxy.

We present experimental and theoretical studies of Pd/Cu(100) and Cu/Pd(100) heterostructures in order to explore their structure and misfit strain relaxation. Ultrathin Pd and Cu films are grown by pulsed laser deposition at room temperature. For Pd/Cu, compressive strain is released by networks of misfit dislocations running in the [100] and [010] directions, which appear after a few monolayers (ML) already. In striking contrast, for Cu/Pd the tensile overlayer remains coherent up to about 9 ML, after which multilayer growth occurs. The strong asymmetry between tensile and compressive cases is in contradiction with continuum elasticity theory and is also evident in the structural parameters of the strained films. Molecular dynamics calculations based on classical many-body potentials confirm the pronounced tensile-compressive asymmetry and are in good agreement with the experimental data.

Journal Article↗

PubMed2002

Surface diffusion anomaly near a substrate phase transition: H on W(100).

Using a linear optical diffraction method, we have experimentally studied the long predicted diffusion anomalous behavior for H/W(100) near the reconstructive phase transition of the W(100) substrate. This anomaly manifests itself in the form of a strong dip in the diffusion coefficient D at the transition temperature T(C). We interpret the strong reduction of D as a result of the diverging friction damping near the transition. The finite dip in D instead of a vanishing D at T(C) also demonstrates the importance of the non-Markovian (memory) deviation from the simple instantaneous damping picture.

Journal Article↗

PubMed2000

Transverse thermal depinning and nonlinear sliding friction of an adsorbed monolayer.

We study the response of an adsorbed monolayer under a driving force as a model of sliding friction phenomena between two crystalline surfaces with a boundary lubrication layer. Using Langevin-dynamics simulation, we determine the nonlinear response in the direction transverse to a high symmetry direction along which the layer is already sliding. We find that below a finite transition temperature there exist a critical depinning force and hysteresis effects in the transverse response in the dynamical state when the adlayer is sliding smoothly along the longitudinal direction.

Adsorption↗

PubMed1998

Recall of old and recent information.

A neural network model for 'forgetting upon learning' is developed in such a way that old information can also be evoked. A new synaptic clipping scheme coupled with selective reinforcement of information is introduced that mimics the learning and memory functions of the 'limbic system' in the brain. The model thus enables both long-term (old) and short-term (recent) memories to exist concurrently, without one affecting the other, as one expects in a realistic situation.

Humans↗

PubMed1996