Articles in 2011

Colloidal particles adsorbed at liquid interfaces are commonly assumed to be at equilibrium, but holographic microscopy experiments now reveal that microspheres bound to a water/oil interface may take months to equilibrate. The observed ageing dynamics agree with a model of thermally activated hopping of the particle/interface contact line over nanoscale surface defects, and have implications for understanding the interactions between adsorbed colloidal particles.

Many synthetic polymer nanoparticles used for non-viral gene delivery contain excess cations on their surface, which makes the particles cytotoxic and the delivery of genes inefficient. Terpolymers with a low charge density, high molecular weight and increased hydrophobicity are now shown to have minimal toxicity, and to efficiently deliver the apoptosis-inducing TRAIL gene to transplanted tumours in mice.

Photonic devices on silicon offer the benefit of combining advanced electronic functionality with the high bandwidth of silicon photonics. Now, efficient second-order nonlinear activity in silicon waveguides strained by a silicon nitride top layer considerably advances the potential of all-optical data management on a silicon platform.

A key step in fuel-cell energy-conversion processes is electro-oxidation of the fuel at the anode, but ways to improve electrocatalytic activity remain unclear. Using ceria–metal structures, H₂-oxidation reactions are shown to be dominated by electrocatalysis at the oxide/gas interface with minimal contributions from the oxide/metal/gas triple-phase boundaries.

Vesicles can rupture as a result of an imbalance in osmotic pressure between their inside and the exterior. Such an ‘osmotic shock’ has now been multiplexed in a coordinated fashion within an ordered material in which a minor component swells and ruptures, thus leading to a porous bicontinuous structure. Such perforated ordered materials may find applications in photonics, optoelectronics and nanofiltration.

The relay mechanism in which hydrogen atom transfer occurs along hydrogen bonds plays a crucial role in many functional compounds. Using a scanning tunnelling microscope, the transfer of hydrogen atoms along hydrogen-bonded chains assembled on a Cu(110) surface is shown to be controllable and reversible.

An efficient scheme that realizes broad tunability of photon upconversion in core–shell nanoparticles may lead to applications in biosensing, security labelling and more.

The synthesis of a family of plate-like semiconductor nanocrystals yields solutions of small quantum wells with excellent optical properties.

The search for the metallic state of hydrogen at ever higher static pressures has normally required experiments to be performed at temperatures near 100 K. Now, some 30 years after the first attempts at room-temperature compression, the observation of reflective dense hydrogen promises to bring it in from the cold.

The 2011 Nobel Prize in Chemistry awarded for the discovery of quasicrystals recognizes a breakthrough that has fundamental scientific consequences.

Elastic thin films attached to a foundation under compression develop wrinkles, which in turn can generate invaginated folds. Hierarchical patterns of localized folds have now been observed in thin films under biaxial compression, which show intriguing resemblance to fracture patterns in drying pastes and to venation networks in leaves.