Condensed Matter Theory

Abstract:

In this work we present a study of the characteristics of UV cure ink droplets on different media (model homogeneous and heterogeneous surfaces, PET, treated PET, etc.). By varying the magnitude of chemical heterogeneities on model surfaces, we are able to highlight the parameters that affect droplet shape. Using Lattice Boltzmann simulations of droplet spreading, we show that the location of the impact point of a droplet on patterned substrate with micron size chemical heterogeneity is an important criterion to consider with respect to the equilibrium shape of a droplet. This allows a complete understanding of the effect of chemical heterogeneity on droplet shape, and therefore on printing quality. We also report an experimental study of the internal morphology of ink droplets adsorbed on chemically defined substrates. This morphology appears to be related with the surface properties of the media considered.

Abstract:

The response of a short DNA segment to bending is studied, taking into account the anisotropy in the bending rigidities caused by the double-helical structure. It is shown that the anisotropy introduces an effective nonlinear twist-bend coupling that can lead to the formation of kinks and modulations in the curvature and/or in the twist, depending on the values of the elastic constants and the imposed deflection angle. The typical wavelength for the modulations, or the distance between the neighboring kinks is found to be set by half of the DNA pitch.