Color changing and lasing stretchable cholesteric films.

Polymer materials able to change reflective properties due to mechanical deformation fundamentally challenge the theory of soft materials and are important for a number of emerging applications. The most promising of those are chiral lasers. In this communication, we report novel cholesteric materials that display large color change from far red to blue and a shift of the position of the selective reflection band under uniaxial strain from near infrared to ultraviolet.

Effects of ultraviolet radiation on the type-I collagen protein triple helical structure: a method for measuring structural changes through optical activity.

A detailed study of the effects of ultraviolet radiation on type-I collagen has been conducted. We have confirmed that exposure to ultraviolet radiation lowers the denaturation temperature of type-I collagen and that the triple helical state is destroyed provided that the radiation dose exceeds a threshold level, which is defined as the incident radiation dose that raises the sample temperature above the (lower) denaturation temperature. For incident radiation doses below threshold, the collagen molecule remains in a triple helical state.