Simulation Approach for Hydrophobicity Replication via Injection Molding.

Nanopattern replication of complex structures by plastic injection is a challenge that requires simulations to define the right processing parameters. Previous work managed to simulate replication for single cavities in 2D and 3D, showing high performance requirements of CPU to simulate periodic trenches in 2D. This paper presents two ways to approach the simulation of replication of complex 3D hydrophobic surfaces. The first approach is based on previous CFD Ansys Fluent and compared to FE based CFD Polyflow software for the analysis of laminar flows typical in polymer processing and glass forming as well as other applications. The results showed that Polyflow was able to reduce computing time from 72 h to only 5 min as desired in the project. Furthermore, simulations carried out with Polyflow showed that higher injection and mold temperature lead to better replication of hydrophobicity in agreement with the experiments. Polyflow simulations are proved to be a good tool to define process parameters such as temperature and cycle times for nanopattern replication.

FUNCTIONALIZED, SWELLABLE HYDROGEL LAYERS AS A PLATFORM FOR CELL STUDIES.

This paper reports the design, synthesis and characterization of thin films as a platform for studying the separate influences of physical and chemical cues of a matrix on the adhesion, growth and final phenotype of cells. Independent control of the physical and chemical properties of functionalized, swellable hydrogel thin films was achieved using initiated Chemical Vapor Deposition (iCVD). The systematic variation in crosslink density is demonstrated to control the swelling ability of the iCVD hydrogel films based on 2-hydroxyethyl methacrylate (HEMA). At the same time, the incorporation of controllable concentrations of the active ester pentafluorophenyl methacrylate (PFM) allows easy immobilization of aminated bioactive motifs, such as bioactive peptides. Initial cell culture results with Human Umbilical Vein Endothelial Cells (HUVEC) indicated that the strategy of using PFM to immobilize a cell-adhesion peptide motif onto the hydrogel layers promotes proper HUVEC growth and enhances their phenotype.

Monte Carlo-MST: New strategy for representation of solvent configurational space in solution.

A new procedure for the representation of the configurational space of solutes in solution is presented. The method is based on the combination of standard Monte Carlo techniques with the continuum model developed by the Pisa group in its semiclassical version, which was developed by our group. The suitability of the method for exploring the configurational space of chemical systems in solution has been tested by analyzing the dimers of formic acid, imidazole, and benzene, as well as the interaction between the ammonium cation and the formate anion. The results in aqueous solution are compared with those obtained in a gas phase environment. The calculations provide detailed information on the interaction modes between monomers and their contribution to the dimer. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 665-678, 1999.