Extensive and subextensive chaos in globally coupled dynamical systems

Using a combination of analytical and numerical techniques, we show that chaos in globally coupled identical dynamical systems, whether dissipative or Hamiltonian, is both extensive and subextensive: their spectrum of Lyapunov exponents is asymptotically flat (thus extensive) at the value λ(0) given by a single unit forced by the mean field, but sandwiched between subextensive bands containing typically O(logN) exponents whose values vary as λ?λ(∞)+c/logN with λ(∞)≠λ(0).     

Structure of a Complex Formed by a Protein and a Helical Aromatic Oligoamide Foldamer at 2.1 Å Resolution

In the search of molecules that could recognize sizeable areas of protein surfaces, a series of ten helical aromatic oligoamide foldamers was synthesized on solid phase. The foldamers comprise three to five monomers carrying various proteinogenic side chains, and exist as racemic mixtures of interconverting right‐handed and left‐handed helices. Functionalization of the foldamers by a nanomolar ligand of human carbonic anhydrase II (HCA) ensured that they would be held in close proximity to the protein surface. Foldamer–protein interactions were screened by circular dichroism (CD). One foldamer displayed intense CD bands indicating that a preferred helix handedness is induced upon interacting with the protein surface. The crystal structure of the complex between this foldamer and HCA could be resolved at 2.1 Å resolution and revealed a number of unanticipated protein–foldamer, foldamer–foldamer, and protein–protein interactions.     

Structure investigation of poly(p-phenylene vinylene)

Electron diffraction patterns of highly oriented poly(p-phenylene vinylene) films obtained by the soluble polymeric precursor route are interpreted on the basis of a monoclinic unit cell containing two monomer units: c (chain axis) = 0.658 nm, a = 0.790 nm, b = 0.605 nm, α ? 123°. The molecules are nearly perfectly oriented along the stretching direction but exhibit partial axial translational disorder.     

Spectrometrie de Masse des Epoxydes Phenyles—II

The fragmentation of aromatic epoxides proceeds either directly through loss of one molecule of aldehyde or ketone which leads to a symmetrical ion, or through rearrangement of the molecular ion into the isomeric carbonyl radical ion. Substituents on the aromatic ring have a marked influence on the fragmentation.     

Composition and plasticizing effect of poly(carboxylic acid) complexes with amino compounds

Poly(carboxylic acid)-dimethylalkylamine complexes were prepared and examined by various methods including infrared spectrometry and chemical titrations. FTIR measurements provided some of the most complete and detailed insights into the type and the stoichiometry of the acid-base complexes. A (1:1) stoichiometric complexation of the poly(carboxylic acid) with tertiary amines was involved in protic solvents. A threshold degree of complexation of 42% was obtained in such a macromolecular system. The equilibrium constant of the proton transfer reaction K was estimated to be independent on the alkyl chain length of the base reagent. Besides the formation of the acid-base complexes, a plasticizing effect of the amine derivatives was demonstrated by differential calorimetry. A T_g depression could be both attributed to the amine molecules linked to the polymer backbone via ionic bonds and to the free molecules dissolved within the free volume of the polymer.     

Quantum repeaters with photon pair sources and multimode memories

We propose a quantum repeater protocol which builds on the well-known Duan-Lukin-Cirac-Zoller (DLCZ) protocol [L. M. Duan, M. D. Lukin, J. I. Cirac, and P. Zoller, Nature (London) 414, 413 (2001)10.1038/35106500], but which uses photon pair sources in combination with memories that allow to store a large number of temporal modes. We suggest to realize such multimode memories based on the principle of photon echo, using solids doped with rare-earth-metal ions. The use of multimode memories promises a speedup in entanglement generation by several orders of magnitude and a significant reduction in stability requirements compared to the DLCZ protocol.     

Slippery or sticky boundary conditions: control of wrinkling in metal-capped thin polymer films by selective adhesion to substrates

Wrinkling patterns at the metallized surface of thin polymer films are shown to be sensitive to the sticky or slippery character of the polymer-substrate interface. Existing theoretical models were expanded to specific boundary conditions (adhesive versus slippery) in order to rationalize these observations. Based on this concept, we were able to propose a new and simple method to orient the wrinkles by chemically patterning the substrate with regions of high and low adhesion.