Using model interaction Hamiltonians for both electrons and phonons and Green's function formalism for ballistic transport, we have studied the thermal conductance and the thermoelectric properties of graphene nanoribbons (GNR), GNR junctions and periodic superlattices. Among our findings we have established the role that interfaces play in determining the thermoelectric response of GNR systems both across single junctions and in periodic superlattices. In general, increasing the number of interfaces in a single GNR system increases the peak ZT values that are thus maximized in a periodic superlattice. Moreover, we proved that the thermoelectric behavior is largely controlled by the width of the narrower component of the junction. Finally, we have demonstrated that chevron-type GNRs recently synthesized should display superior thermoelectric properties.

The electrorheology of a zeolite/silicone oil suspension with direct current (dc) and alternating current (ac) electric fields was determined at room temperature. The shear yield stress changed only slightly with the field frequency, but the current density increased considerably. Good agreement occurs between the experimental results and those predicted by our model for both the shear yield stress and the current density. This study shows that there is a significant electrorheological (ER) effect over a large frequency range when a suspension has both a high conductivity ratio and a high dielectric ratio of the particles to the host oil.