Search results for "surface"

Spinodal decomposition in thin films: Molecular-dynamics simulations of a binary Lennard-Jones fluid mixture

2005

We use molecular dynamics (MD) to simulate an unstable homogeneous mixture of binary fluids (AB), confined in a slit pore of width $D$. The pore walls are assumed to be flat and structureless, and attract one component of the mixture (A) with the same strength. The pair-wise interactions between the particles is modeled by the Lennard-Jones potential, with symmetric parameters that lead to a miscibility gap in the bulk. In the thin-film geometry, an interesting interplay occurs between surface enrichment and phase separation. We study the evolution of a mixture with equal amounts of A and B, which is rendered unstable by a temperature quench. We find that A-rich surface enrichment layers fo…

A molecular dynamics study of large-scale reversible aggregation of anisotropic particles

1992

We report findings of 1000 ps molecular dynamics simulations of a bidimensional system of 4050 Lennard–Jones particles with electric dipoles, undergoing spinodal separation. This simple system is used to model the reversible aggregation of building blocks bearing specific and fixed adhesion sites at their surface. Aggregation regions so obtained resemble images of self-assembled biological structures. Statistical analyses of these regions evidence the interplay of thermodynamic instability and of interaction range between the attachment sites. They also illustrate some basic aspects of the morphogenesis of extended biomolecular/cellular structures, self-organized from initially homogeneous …

Molecular surface area and hydrophobic effect.

1992

[001] Surface Structure in SrTiO3 — Atomistic Study

1998

Thin superconducting films attract great attention as a promising material for plenty of applications. The surface determines most of the physical properties of these films. We studied the polarization effect for the [001] surface of perovskite ABO 3 superconducting crystals on the example of SrTiO 3. Optimization of the ion positions in several surface layers is provided. These ions are placed in the external field of the rest crystal. The interaction between ions is described by means of the shell model technique. We show that Ti +4, Sr 2+ and O -2 ions displace differently from their crystalline sites, which leads to the creation of a dipole moment in the near-surface region.

Supersaturation and Crystal Nucleation in Confined Geometries

1998

Surface aggregation as a necessary condition for interfacially induced crystal nucleation is studied with a surface forces apparatus (SFA).1-3 As a model system, we use the chloride salt of the rod...

Surface topography of membrane domains

2010

金沢大学理工研究域数物科学系

Application of fractal geometry to dissolution kinetic study of a sweetener excipient

2001

Abstract In the context of relationship study between dissolution kinetic and particle morphology using the fractal geometry tool, we use a commercially available quality of saccharin powder. The characterization of molecular feature and image analysis study allows us to conclude to the statistic self-similarity of particles of four sieved particles size fractions, permitting the fractal approach. Calculation of reactive fractal dimension is performed using two forms of mass transfer equation: −d Q /d t = kQ D R /3 Δ C and −d Q /d t = k′R D R −3 Δ C , with Δ C ={ C f /[ln  C s /( C s − C f )]}. Based on comparison of the surface fractal dimension D S on the two values of reactive fractal di…

Packing meterials with surface barriers, controlled distribution and topography of ligands for sample clean-up and analysis of biologically active so…

1991

Various types of, so-called, restricted access packings have been developed for sample clean-up and analysis of biologically active solutes by means of HPLC. The unique feature of these packings is that they prevent the access of matrix components such as protein whilst selectively retaining the drug components and their metabolites. This results from the fact that the particles of the packings possess a surface barrier for large solutes at the external or internal surface area and exhibit a controlled gradient in the chemical surface composition. They are grouped, according to their particle structures, into internal-surface reversed phases (ISRP), shielded hydrophobic phases (SHP), semi-p…

Boolean operations with implicit and parametric representation of primitives using R-functions

2005

We present a new and efficient algorithm to accurately polygonize an implicit surface generated by multiple Boolean operations with globally deformed primitives. Our algorithm is special in the sense that it can be applied to objects with both an implicit and a parametric representation, such as superquadrics, supershapes, and Dupin cyclides. The input is a constructive solid geometry tree (CSG tree) that contains the Boolean operations, the parameters of the primitives, and the global deformations. At each node of the CSG tree, the implicit formulations of the subtrees are used to quickly determine the parts to be transmitted to the parent node, while the primitives' parametric definition …

Multiresolution Analysis for Irregular Meshes

2003

International audience; The concept of multiresolution analysis applied to irregular meshes has become more and more important. Previous contributions proposed a variety of methods using simplification and/or subdivision algorithms to build a mesh pyramid. In this paper, we propose a multiresolution analysis framework for irregular meshes with attributes. Our framework is based on simplification and subdivision algorithms to build a mesh pyramid. We introduce a surface relaxation operator that allows to build a non-uniform subdivision for a low computational cost. Furthermore, we generalize the relaxationoperator to attributes such as color, texture, temperature, etc. The attribute analysis…