Volume 9 Issue 8, August 2010

Aluminium is regarded as a simple system in which to test for phenomena occurring at high pressure. Ab initio calculations now show that this metal undergoes a surprising transition to an incommensurate structure when it is subjected to extremely high pressures.

A new material designed from first principles and subsequently synthesized and characterized in the laboratory may shed light on why there is much more matter than antimatter in the Universe.

The functionalization of crystalline porous materials is frequently limited to groups inert to the microscopic structure. Photoconversion of dormant precursors into highly reactive species shines light on the problem.

Directed assembly of molecular precursors allows the fabrication of graphene nanoribbons with atomic precision.

Imprinting molecular memory on the surface of polymer nanoparticles creates artificial antibodies that can recognize and neutralize a toxic peptide in vivo.

Friction is rarely studied at high sliding speeds between surfaces. However, simulations now suggest that gold clusters on atomically flat graphite can enter a new regime of ballistic friction, featuring a peculiar anticorrelation between translation and rotation.

The versatility and potential of conjugated organic materials continues to amaze, with their unique — and sometimes unexpected — properties being continuously discovered and harnessed by scientists in an attempt to use them in functional devices.

The amorphous nature of metallic glasses makes them interesting for structural applications. However, the interplay between the nature of atomic structures and mechanical properties remains poorly understood. Dynamic micropillar tests now show the important contribution of the inelastic deformation of atomistic free-volume zones to the deformation behaviour of metallic glasses.

What happens to a crystal placed under a huge pressure? In the case of aluminium, it is now shown that the standard, low-pressure close-packed structure transforms into an open one, with incommensurate host–guest arrangement. The findings could have important implications for a wider range of elements.

Regardless of what the origin of superconductivity is in the recently discovered iron-based superconductor, it would be useful to know how good these materials are for applications. Sophisticated experiments now show that SmFeAs_0.75F_0.25 exhibits a high and nearly isotropic critical current, a potentially important result for their use in applications.

Friction between two surfaces is usually studied at low relative sliding speeds. A molecular dynamics study now explores friction at high speeds, showing the emergence of a ballistic friction regime, qualitatively different from standard drift friction. The findings might have important implications for applications in nanoelectromechanical systems.

An important component of spintronics devices is the magnetic electrode, which is usually made from an inorganic alloy. However, an organic-based spin polarizer is now demonstrated, opening new possibilities for developing organic/inorganic hybrid spintronics devices.

Fibres are typically used as passive devices, whether in fibre-optical cables used in telecommunciations or as yarns for clothing. The demonstration of polymer-based piezoelectric fibres that can be drawn to tens of metres in length, and whose acoustic response can be actively controlled, suggests possible applications in, for example, medical imaging or acoustic sensing.

In the standard model of particle physics the permanent electric dipole moment of particles is zero, although competing theories suggest it must exist to explain the asymmetry of matter and antimatter in the Universe. The design and synthesis of a new multiferroic material may now enable us to search for the electric dipole moment of electrons with unprecedented precision.

The manipulation of spin states is a key requirement in spintronics. In semiconductor microcavities, a multistate switching of the spin state of polaritons, which form as a result of the coupling of photons and excitons in the microcavity, may lead to new spintronics devices.

Nanoscale porous materials show unique properties that can be important for catalytic, separation and gas-storage applications. A strategy to yield crystalline porous compounds decorated with reactive nitrenes that can chemically trap and convert guest molecules by light stimulation is now reported.

Synthetic solid-state nanopores are of interest at present for their use as single-molecule sensors for characterization and detection of biomolecules. By using self-assembly evaporation and atomic-layer deposition, kinked silica nanopores are shown to exhibit reduction in DNA-translocation velocity and selectivity.

The detailed mechanism of the pH-dependent quenching of semiconductor quantum-dot/dopamine conjugates, confirming quinone as the electron acceptor in the process, is now reported. This electrochemical knowledge of the bioconjugate system is used for the in vitro detection of drug-induced intracellular pH changes.