Biomedical subjects

S H Garofalini

Publications and source records attributed to S H Garofalini.

3 recordsLinked to original sources

PubMed2005

Determining the radial pair-distribution function within intergranular amorphous films by numerical nanodiffraction.

We report on an alternative method to electron nanodiffraction and fluctuation microscopy for the determination of the reduced density function G(r) of amorphous areas with small cross-sections. This method is based on the numerical extraction of diffraction data from the complex-valued exit-face wave function as obtained by HRTEM focal series reconstruction or electron holography. Since it is thus possible to obtain "diffraction data" from rectangular areas of any aspect ratio, this method is particularly suited for intergranular glassy films of only 1-2 nm width, but lengths of several 100 nm. A critical comparison of this method with the already established nanodiffraction and fluctuation microscopy will be made.

Electronic Data Processing↗

PubMed2005

Application of the Wolf damped Coulomb method to simulations of SiC.

A multibody interatomic potential is developed for bulk SiC using a modification of the Wolf et al. summation technique [D. Wolf, P. Keblinski, S. R. Phillpot, and J. Eggebrecht, J. Chem. Phys. 110, 8254 (1999)] for the electrostatic interaction. The technique is modified to account for the short-range nonpoint charge effect. The nonelectrostatic interaction is modeled by a simple Morse-stretch term. This potential is then applied to beta-SiC to calculate various bulk properties using molecular dynamics simulations. The simulated x-ray diffraction pattern, radial distribution functions, lattice constant, elastic constants, and defect energy agree well with experimental data.

Journal Article↗

PubMed2004

Systematic study of the effect of disorder on nanotribology of self-assembled monolayers.

The adhesion and friction between pairs of ordered and disordered self-assembled monolayers on SiO2 are studied using molecular dynamics. The disorder is introduced by randomly removing chains from a well ordered crystalline substrate and by attaching chains to an amorphous substrate. The adhesion force between monolayers at a given separation increases monotonically with chain length at full coverage and with coverage for fixed chain length. Friction simulations are performed at shear velocities between 0.02-2 m/s at constant applied pressures between 200 and 600 MPa. Stick-slip motion is observed at full coverage but disappears with disorder. With random defects, the friction becomes insensitive to chain length, defect density, and substrate.

Journal Article↗