Conformations and effective interactions of polymer coated nanoparticles at liquid interfaces

We investigate conformations and effective interactions of polymer-coated nanopar- ticles adsorbed at a model liquid-liquid interface via molecular dynamics simulations. The polymer shells strongly deform at the interface, with the shape governed by a balance between maximising the decrease in interfacial area between the two solvent components, minimising unfavourable contact between polymer and solvent and max- imising the conformational entropy of the polymers. Using potential of mean force calculations we compute the effective interaction between the nanoparticles at the liquid-liquid interface. We find that it differs quantitatively from the bulk and is sig- nificantly affected by the length of the polymer chains and by the solvent quality. Under good solvent conditions the effective interactions are always repulsive and soft for long chains. The repulsion range decreases as the solvent quality decreases. In particular, under poor solvent conditions, short chains may fail to induce steric repul- sion, leading to a net attraction between the nanoparticles, whereas with long enough chains the effective interaction potential may feature an additional repulsive shoulder at intermediate distances

Assessing the risk of minimally-invasive surgery: a metrological approach

Principles of uncertainty evaluation for measurement processes and capability studies for production processes are established in many producing enterprises to ensure capable processes. Together with further quality management methods this allows to estimate and minimize the risk of producing defective parts and of taking wrong decisions about the part’s conformity with its specification. This understanding is also desirable for a completely different field, for medical surgery. To quantify the risk of minimally invasive surgery for an individual patient, principles of metrology and production engineering are transferred to the medical domain and are exemplarily applied to minimally invasive surgery at the inner ear. It is shown how the main influencing factors, the uncertainty of the imaging and image processing and the uncertainty of the navigation process of the surgical instrument can be estimated with methods from production metrology. Furthermore, it is shown how these factors contribute to quantifying the patient’s risk of a specific surgery by contributing to a therapeutic risk indicator (TRI)

Assembly of Nanoparticles at Liquid Interfaces: Crowding and Ordering

Experiments with the self-assembly of nanoparticles at liquid interfaces suggest that cooperative and slow dynamical processes due to particle crowding at the interface govern the adsorption and properties of the final assembly. Here we report a numerical approach to studying nonequilibrium adsorption, which elucidates these experimental observations. The analysis of particle rearrangements shows that local ordering processes are directly related to adsorption events at high interface coverage. Interestingly, this feature and the mechanism coupling local ordering to adsorption do not seem to change qualitatively upon increasing particle size polydispersity, although the latter changes the interface microstructure and its final properties. Our results indicate how adsorption kinetics can be used for the fabrication of 2D nanocomposites with controlled microstructure