Volume 8 Issue 5, May 2009

Nature Materials spoke to Thirumalachari Ramasami, the Secretary of State in India's Department of Science and Technology, about the many challenges facing scientific research and development in India.

Solution-based syntheses of nanoclusters typically produce a broad range of species. A step-by-step process using DNA-encoded nanoparticles assembled on a solid support aids in the design and production of specific self-assembled nanoclusters in high yields.

Theoretical advances demonstrating an improved dielectric response in nanocapacitor structures will lead to advanced electronics with greatly increased memory densities.

Ultrapure, isotopically engineered diamonds show record spin coherence times. The ideal spin-free material for quantum information processing and magnetometry is one step closer.

It's been possible for some time to create proteins synthetically, but cell-free gels that can produce proteins up to 300 times as efficiently as solution processes could provide new directions and greater complexity in synthetic biology.

One-dimensional islands that grow during ice nucleation at low temperatures on a copper(110) surface are identified as chains of water-molecule pentagons. This unexpected molecular arrangement optimizes oxygen-atom proximity to preferred bonding sites on the metal, while minimizing strain in the hydrogen-bond network.

The synthesis of highly pure diamond nanocrystals with a very small amount of paramagnetic impurities allows the observation of electron spin-dephasing times of up to 1.8 ms, a record for solid-state materials. The result could have important implications for quantum information processing methods based on diamond.

Solution-based syntheses of nanoscale clusters using biomolecules as links between nanoparticles are frequently inefficient and normally produce many different multimers or isomers of clusters. Dimer nanoclusters and Janus nanoclusters have now been designed and produced in high yields using nanoparticles grafted with single-stranded DNA.

The size reduction of thin-film ferroelectric capacitors has been hampered by effects that arise as ferroelectric films reach only a few unit cells in height. However, rather than inevitably resulting in a ‘dead layer’, an enhancement of ferroelectricity at certain metal–oxide interfaces is now predicted.

Applications of high-temperature superconductivity rely on transporting a large current without dissipation. It is now shown how the inclusion of a combination of two types of defect can be used to control and optimize the performance of the high-temperature superconductor YBa₂Cu₃O₇.

Freezing water containing salts is believed to produce pure ice and a salt hydrate. Neutron-diffraction measurements of the ice phase obtained by recrystallizing the glassy state of LiCl salt solution at high pressure suggests something different. The data reveal an ‘alloyed’ ice VII structure incorporating Li and Cl ions.

Microstructure evolution in complex nonlinear systems, such as quasiperiodic two-phase chessboard structures, is a fascinating fundamental phenomenon. It is demonstrated that under certain conditions a transformation from tweed to nanowire chessboards develops by spinodal decomposition.

Explaining the quantitative relationships between processing conditions and oxide-layer geometry for the growth of porous anodic alumina has so far proved difficult. A model for steady-state growth of these amorphous films, incorporating metal and oxygen ions transported by plastic flow and coupled electrical migration, is now proposed.

Discotic liquid crystals are materials with high charge-carrier mobility, which are promising for molecular electronics. They self-organize into stacks, usually with a twist of 30^∘, but the shape and periphery of the molecules can now be altered to produce materials with a twist of 60^∘. Defect-limited mobilities of these materials reach 0.2 cm² V⁻¹ s⁻¹, but the potential defect-free mobility could be up to 10 cm² V⁻¹ s⁻¹.

Although heterogeneous ice nucleation is investigated in a number of fields, a mechanism for the process remains elusive. Ice with a pentagon-based chain structure is now seen to form on a Cu(110) surface, revealing that the structure of ice–water films can adapt to maximize water–metal bonding and achieve strong hydrogen bonding within the layer.

Proteins are usually produced in living cells, but hydrogels that incorporate genes demonstrate that cells aren’t always needed. The gels produce a wide variety of proteins without cells, and with higher yields than the equivalent solution method. Materials-related proteins that have been difficult to produce by other methods can now be made in greater quantities.