Volume 9 Issue 7, July 2010

The historical trajectory of materials science in Brazil shows the fast establishment of a high-quality, sizeable and productive scientific community. It is now time for a change in attitude towards real innovation and excellence.

Sergio Machado Rezende has served for 5 years as the Minister for Science and Technology of Brazil. Nature Materials has asked him about the past and future of science in his country.

Heating and cooling of peptide amphiphile suspensions converts disorganized nanofibres into liquid-crystalline nanofibre bundles that gel on addition of salts. The noodle-shaped strings of gel can entrap and align cells.

Ternary intermetallic Heusler compounds, originally discovered by a German mining engineer and chemist in 1903, may show exotic topological insulator behaviour unknown to science just five years ago.

A cationic nanosized hydrogel (nanogel) shows controlled antigen delivery in vivo following intranasal administration and hence holds promise for a clinically effective adjuvant-free and needle-free vaccine system.

A new route to layer-by-layer assembly of metal–organic framework thin films affords highly ordered and controllable surfaces with potential in chemical sensing and catalyst applications.

Topological insulators have been predicted and recently demonstrated experimentally in a series of binary alloys. It is now show theoretically that about 50 Heusler compounds show features similar to those of the confirmed topological insulator HgTe, which considerably expands the possibility of realizing quantum topological phenomena.

Topological insulators have been predicted and recently demonstrated experimentally in a series of binary alloys. It is now show theoretically that ternary half-Heusler alloys have electronic properties similar to those of the experimentally verified topological insulators, and represent a platform for observing quantum topological phenomena.

When a superconductor is shrunk to the nanoscale, quantum size effects are predicted to strongly influence superconductivity. This is now demonstrated in Sn nanoparticles in which a reduction in size leads to a substantial enhancement of the superconducting gap.

The ability to propagate heat in a film should improve with increasing thickness. However, graphene has a higher thermal conductivity than graphite, despite having a smaller thickness. The crossover from two-dimensional to bulk graphite is now studied experimentally and explained theoretically. The results may pave the way to thermal management applications in nanoelectronics.

The search for active semiconductor photocatalysts that split water directly under visible-light irradiation remains challenging for solar applications. An orthophosphate semiconductor, Ag₃PO₄, which is capable of harnessing visible light to oxidize water as well as decompose organic contaminants in aqueous solution is now reported.

For metal–organic frameworks to be used for applications such as gas storage it is necessary to direct their assembly. Here, thin crystalline films of metal–organic frameworks are fabricated on a solid surface with structural growth control over both in-plane and out-of-plane orientations relative to the substrate.

Mucosal diseases are becoming more prevalent and needle-free vaccines could be instrumental in combating this. A nanometre-sized hydrogel consisting of a cationic type of cholesteryl group bearing pullulan has now been used as an intranasal vaccine-delivery system.

The control of magnetic properties by electric fields is key to realizing spintronics devices. The surface of the antiferromagnetic magnetoelectric Cr₂O₃ is now shown to exhibit room-temperature ferromagnetism, whose direction can be switched by an electric field. This magnetization switches the exchange-bias field with magnetic multilayers grown on Cr₂O₃, promising a new route towards room-temperature spintronics devices.

There has been an intense search in recent years for long-lived spin-polarized carriers for spintronics and quantum computing devices. It is now shown that spin-polarized quasiparticles in superconducting aluminium layers have surprisingly long spin lifetimes, nearly a million times longer than in their normal state.

Peptide-based molecules that self-assemble into lamellar plaques with fibrous texture on heating, subsequently break on cooling to form long-range aligned bundles of nanofibres. This thermal route to monodomain gels is compatible for living cells and allows the formation of noodle-like viscoelastic strings of any length.

During the past 15 years, Brazil's economy has been growing steadily, and there is No. sign that this will change any time soon. In this issue we take a closer look at how the economic growth has influenced science in the country.