No abstract

No abstract

No abstract

No abstract

Clay minerals such as the layered silicates montmorillonite and vermiculite, as well as the fibrous clay sepiolite, and a layered double hydroxide ([Zn2Al(OH)6]Cl.nH2O) have been used to prepare gelatin-clay micro- and nano-composites. This biopolymer can be assembled to those inorganic solids through interactions at the nanometric range, but only in the case of montmorillonite intercalation of gelatin takes place. One of the most salient features of the resulting bio-nanocomposites is the possibility to be processed as homogeneous thin films provided of good mechanical properties and transparency. The Young's modulus of gelatin-sepiolite bio-nanocomposites may increase by a factor of 2.5 with respect to neat gelatin. The incorporation of pH indicator dyes to the montmorillonite bio-nanocomposite films allows their application for optical pH sensing.

No abstract

We report on the selectivity of growth on patterned GaAs (311)A substrates by solid-source molecular beam epitaxy. For mesa stripes oriented along the [01-1] direction, the selectivity of growth is qualitatively different from that on patterned GaAs (100) substrates with a higher growth rate on one of the side facets of the stripes. This growth mode develops a convex curved surface profile enclosing thicker wirelike regions of GaAs due to preferential migration of Ga atoms from both sides toward the sidewall leaving behind thinner regions on the adjacent mesa top and bottom areas. A mechanism for the formation of the surface profile is proposed.

No abstract