Histochemical and ultrastructural analyses of adhesive setae of lizards indicate that they contain lipids in addition to keratins.

We studied the distribution of lipid material and organelles in the epidermal layers of toe pads from two species of lizards representing the two main lizard families in which adhesive scansors are found (gekkonids and polychrotids), the dull day gecko, Phelsuma dubia and the green anole, Anolis carolinensis. Although lipids are a conspicuous component of the mesos layer of squamate reptiles and function in reducing cutaneous water loss, their distribution has not been specifically studied in the highly elaborated epidermal surface of adhesive toe pads. We found that, in addition to the typical cutaneous water loss-resistant mesos and alpha-layer lipids, the Oberhutchen (including the setae) on the most exterior layers of the epidermis in P. dubia and A. carolinensis also contain lipid material. We also present detailed histochemical and ultrastructural analyses of the toe pads of P. dubia, which indicate that lipid material is closely associated spatially with maturing setae as they branch during the renewal phase of epidermal regeneration. This lipid material appears associated with the packing of keratin within setae, possibly affecting permeability to water loss in the pad lamella, where the surface area is from 4­60-fold greater compared with normal scales.

Melting at alkyl side chain comb polymer interfaces.

Infrared visible sum frequency generation (SFG) spectroscopy has been used to study structure and melting transition temperatures of alkyl-side chain-acrylate comb polymers at air and solid interfaces. At the air interface, the SFG spectra show methyl bands and two transitions are observed: the first, near the bulk melting temperature, T(m), and the second 10-20 degrees C higher than T(m). The shorter the alkyl side chain, the larger the difference between the two transition temperatures. In contrast, methylene bands are observed at sapphire interface with a single transition near T(m) (C18).

Molecular structure of polystyrene at Air/Polymer and Solid/Polymer interfaces

IR-visible sum-frequency generation (SFG) spectroscopy has been used in a total internal reflection geometry to study the molecular structure of polystyrene (PS) at PS/sapphire and PS/air interfaces, simultaneously. The symmetric vibrational modes of the phenyl rings dominate the SFG spectra at the PS/air interface as compared to the antisymmetric vibrational modes at the PS/sapphire interface. This indicates approximately parallel orientation of the phenyl rings at the PS/air interface while nearly perpendicular orientation at the PS/sapphire interface, with respect to the surface normal.