Volume 524

  • No. 7566 27 August 2015

    Gold nanocrystals visualized doping a semiconductor superlattice without disrupting the ordered arrays. Doping � widely used in semiconductors, diluted magnetic materials and phosphors � is a process in which extraneous atoms are introduced into a host material in order to improve or create new electronic, magnetic and optical properties. Christopher Murray and colleagues introduce the concept of substitutional doping in nanocrystal superlattices, where artificial atoms (uniform nanocrystals) are used instead of atoms. They demonstrate the random incorporation of gold nanocrystals into a semiconductor (CdSe or PbSe) nanocrystal superlattice, where one nanocrystal can be replaced with another of the same size but different composition. The conductivity of the resulting material is modulated by metallic percolation pathways controlled by the density and distribution of the dopants. The use of self-assembly means that this novel technique should be widely applicable to a range of different materials and compositions. Cover image: Ella Marushchenko.

  • No. 7565 20 August 2015

    A coated ‘dirty� diamond, created when a microinclusion-bearing fibrous coat is overgrown on a monocrystalline clear diamond. Most of the diamonds found near the Earth’s surface arose at depths of more than 150 km in the roots of old continents. Chemical impurities bottled up in dirty diamonds therefore hold valuable information about these deep, inaccessible regions of the Earth. Yaakov Weiss and co-authors present geochemical data from inclusions within a suite of eleven diamonds from the Ekati mine from the Northwest Territories, Canada. The data contain a clear chemical evolutionary trend that indicates the involvement of highly saline solutions in the formation of silicic and carbonatitic deep mantle melts. The chemistry of the saline fluids and the timing of host diamond formation suggest a subducting plate under western North America as the source of the fluids, implying a strong association between subduction, mantle metasomatism and fluid-rich diamond formation. This new model provides a context for resolving the effects of the compositional spectrum of mantle fluids, which alter the deep lithosphere globally and play key roles in diamond formation. Cover: Graham Pearson

  • No. 7564 13 August 2015

    The California two-spot octopus (Octopus bimaculoides) displays several cephalopod morphological innovations, including powerful sucker-lined prehensile arms and sophisticated camera-like eyes. Octopuses have been called ‘the most intelligent invertebrate�, with a host of complex behaviours, and a nervous system comparable in size to that of mammals but organized in a very different manner. It had been hypothesized that, as in vertebrates, whole-genome duplication contributed to the evolution of this complex nervous system. Caroline Albertin et al. have sequenced the genome and multiple transcriptomes of O. bimaculoides and find no evidence for such duplications but there are large-scale genome rearrangements closely associated with octopus-specific transposable elements. The core developmental and neuronal gene repertoire turns out to be broadly similar to that of other invertebrates, apart from expansions in two gene families formerly thought to be uniquely expanded in vertebrates � the protocadherins (cell-adhesion molecules that regulate neural development) and the C2H2 superfamily of zinc-finger transcription factors. Cover: Judit R. Pungor.

  • No. 7563 6 August 2015

    Mawa, Bong County, Liberia, in September 2014. The current Ebola virus disease outbreak in West Africa is rumbling on ï in the week to 22 July WHO reported 22 confirmed cases in Guinea, 4 in Sierra Leone and none in Liberia where the outbreak was declared ïover on 9 May. This issue of Nature features comment on the lessons learned in coping with the outbreak and on how this and other diseases might be contained in the future. Cover: Benedicte Kurzen/NOOR/eyevine