CHEMISTRY: Wringing Non-Shrink Gels

Wringing out DNA.

The chiral nature of DNA plays a crucial role in cellular processes. Here we use magnetic tweezers to explore one of the signatures of this chirality, the coupling between stretch and twist deformations. We show that the extension of a stretched DNA molecule increases linearly by 0.42 nm per excess turn applied to the double helix. This result contradicts the intuition that DNA should lengthen ...

Functional Polymer Gels by Click- and Supramolecular Chemistry

Colloidal gels: equilibrium and non-equilibrium routes

We attempt a classification of different colloidal gels based on colloidcolloid interactions. We discriminate primarily between non-equilibrium and equilibrium routes to gelation, the former case being slaved to thermodynamic phase separation while the latter is individuated in the framework of competing interactions and of patchy colloids. Emphasis is put on recent numerical simulations of col...

Shrink-wrap vesicles.

We describe a simple approach to the controlled removal of molecules from the membrane of large unilamellar vesicles made of fatty acids. Such vesicles shrink dramatically upon mixing with micelles composed of a mixture of fatty acid and a phospholipid (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)), as fatty acid molecules leave the vesicle membrane and accumulate within the mixed mi...

Shrink Indecomposable Fractals

Iterated Function Systems (IFSs) are among the best-known methods for constructing fractals. The sequence of pictures E0; E1; E2; : : : generated by an IFS fX; f1; f2; : : : ; ftg converges to a unique limit E , which is independent of the choice of starting set E0, but completely determined by the choice of the maps fi. Random context picture grammars (rcpgs) are a method of syntactic picture ...