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Graphene nanoribbons, elongated strips of graphite an atom thick, could be even more effective than carbon nanotubes in some future electronic devices. The cover illustrates one of two new ways of making nanoribbons in bulk quantities from carbon nanotubes, reported in this issue by James Tour and colleagues and Hongjie Dai and colleagues. [Cover image: D. Kosynkin/Rice Univ.]
As the launch of the Planck spacecraft approaches, Eric Hand investigates what the mission could mean for the predominant theory of the moments after the Big Bang.
Could genes explain the remarkable rate of identical twins born in some remote villages around the world? David Cyranoski investigates a long-standing biological curiosity.
Biologists have tended to assume that closely related species will have similar cognitive abilities. Johan J. Bolhuis and Clive D. L. Wynne put this evolutionarily inspired idea through its paces.
Astronomer François Arago of the Paris Observatory defied war, disease and death to survey the meridian running through his city — and helped define the metric system we use today, explains Andrew Robinson.
Behind the novelist's eye of Tom Wolfe — bestselling author of Bonfire of the Vanities — lies a keen interest in brain science. Discussing the origin of language this week with Steven Pinker at the Brainwave festival in New York, Wolfe explains why he sees human behaviour as more than mechanistic, and genetic theory as little more than literature.
To lose weight, would you rather diet, exercise or subject yourself to cool temperatures? The last choice is not such an odd one, as adult humans have brown fat tissue that burns calories in response to cold.
Nature often adopts several approaches to crack the same problem. The finding that the mechanism of a crucial enzyme in certain disease-causing bacteria differs from that in mammals offers scope for drug discovery.
The conventional approach to flipping electron spins in a semiconductor requires an external alternating field. It seems that the same job can be accomplished without external excitation of any kind.
Regulating neuronal development can be complicated. But genetic control of neurotransmitter expression — as exemplified by differentiation of dopamine-secreting neurons — turns out to be relatively straightforward.
Magnetic resonance imaging offers rich three-dimensional pictures, but with limited resolution. Imaging at the nanometre scale has now become possible using highly sensitive force-detection techniques.
Nanotubes are single sheets of graphite rolled up into a cylinder. But no one thought that nanotubes could be cut along their axis and flattened out to make such sheets. Until now.
Cosmic rays are charged particles arriving at Earth from space. Those at the highest energies are particularly interesting because the physical processes that could create or accelerate them are at the limit of our present knowledge. The Pierre Auger Observatory is the largest cosmic-ray detector on Earth, and as such is beginning to resolve past observational disagreements regarding the origin and propagation of these particles.
In this study, Watanabe and colleagues investigate the contribution of kinetochore geometry as a determinant for bipolar versus monopolar attachment. They find that cohesion at the core centromere induces a monopolar attachment seen in meiosis I; in contrast, cohesion at the peri-centromeric region promotes bipolar attachment in mitosis.
In this manuscript, the authors develop a computational framework to design protein peptide interactions, and they use the method to identify peptides that bind to human bZIP transcription factors. Despite that fact that bZIP proteins share strong sequence and structural similarities, the authors were able to find peptides that selectively bound to one family, but not the 19 other families.
A key missing piece in the puzzle of supernovae is the difficulty of identifying and studying progenitor stars; in only a single case (SN 1987A) has a star been detected at the supernova location before the explosion. The proposed progenitor of supernova SN 2005gl has now been confirmed by Gal-Yam and Leonard as indeed the progenitor of that supernova; standard stellar evolution predicts that this very massive luminous blue variable should not have exploded in that state.
Electron spin resonance produced by high-frequency magnetic or electric fields has wide applications. The authors report a type of electron spin resonance that does not require external driving fields; electrons bouncing back and forth in micrometre-scale channels of a semiconductor structure undergo spin resonance through an effective magnetic field that oscillates owing to the repeated wall reflections, with typical frequencies (~20-100 GHz) that are attractive for modern spin resonance applications.
Graphene nanoribbons have important electronic properties — as their width increases they change from semiconductor to semi-metal — but it has been difficult to make large quantities. To do so, Tour et al. simply longitudinally unzip multiwalled carbon nanotubes with permanganate in acid to form graphene oxide, which is then reduced to restore electronic conductivity. The ribbons are about 100 nm wide (thinner ones tend to 'mat'), and the authors use them to make field-effect transistors.
Unlike graphene itself, or carbon nanotubes, very narrow nanoribbons of graphene are completely semiconducting. Dai and colleagues reliably produce bulk quantities of sub-10 nm graphene nanoribbons by partial encapsulation of carbon nanotubes in a polymer. The exposed part of the nanotube can be cut by plasma etching, so that the nanotube unzips when the polymer is removed, leaving a very thin strip of graphene.
Knowing the rate at which the sea-level rose 4-6 m (highstand) during the last interglacial period could help us assess whether such rapid ice loss could lead to future catastrophic sea-level rise. Blanchon and co-authors date a fossil coral reef from the Yucatan peninsula, Mexico, to present a complete highstand reef-crest sequence and its U-series chronology. They find that the reef back-stepped to 6 m, which they infer occurred rapidly, and was triggered by a 2-3 m jump in sea level during a time of ice-sheet instability.
The authors reveal that the regulatory protein AST-1 is necessary and sufficient to drive and maintain the terminal differentiation of dopaminergic neurons in C. elegans. Because the protein and its terminal differentiation function are strikingly conserved in mice, the results have direct implications for stem-cell replacement strategies in numerous dopamine-related disorders, such as Parkinson's disease.
Neisseria meningitidis possesses a surface protein called fHbp that binds to the complement regulator factor H, thereby interfering with the host immune response. Now the structure of N. meningitidis fHbp bound to factor H is presented, revealing the molecular interactions between these two molecules.
This study shows that mice lacking the Fto gene do not grow properly after birth, and have less adipose tissue and lean body mass. This is due to increased energy expenditure and systemic sympathetic activation, even though these mice move less and eat lots.
This study shows that dendritic cells use the C-type lectin CLEC9A to sense necrotic cell debris and to mediate cross-presentation of dead-cell-associated antigens.
This paper shows that in response to treatment of mice with interferon-α (IFNα), haematopoietic stem cells exit the dormant stage and enter an active cell cycle, The data may help to clarify the clinical effects of IFNa on leukaemic cells, and raise the possibility for new applications of type I interferons to target cancer stem cells.
This paper reports the crystal structure of the amino terminus of the PA subunit of the influenza RNA polymerase, and provides evidence that it has endonuclease activity.
The amino terminal domain of influenza virus polymerase PA subunit is shown to harbour the endonuclease activity required for the cap-snatching mechanism of viral mRNA synthesis.
This paper reports an example of thymidylate biosynthesis that occurs without an enzymatic nucleophile, and is found in organisms containing the thyX gene (encoding a flavin-dependent thymidylate synthase). Because several human pathogens depend on this biosynthetic pathway for DNA biosynthesis, it may be possible to develop new, highly selective antibiotics that target this enzyme.
Advances in magnetic resonance imaging are helping scientists learn more about the structure and function of the brain. Nathan Blow looks at how far the technology has developed and where it could go.