July 2011 Volume 10, Issue 7

Editorial

Measuring impact p477
doi:10.1038/nmat3063
Citation analyses can condense scholarly output into numbers, but they do not live up to peer review in the evaluation of scientists. Online usage statistics and commenting could soon enable a more refined assessment of scientific impact.
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Interview

The best we have pp478 - 479
Interview with Pavel Exner
doi:10.1038/nmat3045
Pavel Exner, the newly elected Vice President of the European Research Council and Scientific Director of the Doppler Institute for Mathematical Physics and Applied Mathematics in Prague, talked to Nature Materials about his role in the European funding institution, the value of peer review in identifying the best scientists, the rise of science metrics and the challenges of running an efficient evaluation system.
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Research Highlights

Our choice from the recent literature p480
doi:10.1038/nmat3062
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News and Views

Letters

Direct tomography with chemical-bond contrast pp489 - 493
Simo Huotari, Tuomas Pylkkänen, Roberto Verbeni, Giulio Monaco and Keijo Hämäläinen
doi:10.1038/nmat3031
Although X-ray tomography has proven to be an efficient tool for three-dimensional imaging, its application to light materials has not been too successful. A new X-ray spectroscopy tomography method has now been developed that allows the mapping of chemical bonding in various types of structures, as well as the imaging of soft materials in three dimensions.
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Arrays of indefinitely long uniform nanowires and nanotubes pp494 - 501
Mecit Yaman, Tural Khudiyev, Erol Ozgur, Mehmet Kanik, Ozan Aktas, Ekin O. Ozgur, Hakan Deniz, Enes Korkut and Mehmet Bayindir
doi:10.1038/nmat3038
Nanowires have many applications across a number of disciplines. So far, their length has been largely limited to mesoscale dimensions. Through the adaption of an iterative fibre-drawing process it is now possible to fabricate millions of ordered nanowires and nanotubes of almost infinite length.
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Supramolecular spin valves pp502 - 506
M. Urdampilleta, S. Klyatskaya, J-P. Cleuziou, M. Ruben and W. Wernsdorfer
doi:10.1038/nmat3050
In macroscopic spin valves, the current between two magnetic electrodes can be tuned by external magnetic fields. Here, a molecular-scale spin valve is demonstrated in which a single-molecule magnet, through its localized magnetic moment, modulates the conductance of a single-walled carbon nanotube quantum dot with magnetoresistance ratios reaching 300%.
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See also: News and Views by Sanvito

Linear coupling of alignment with transport in a polymer electrolyte membrane pp507 - 511
Jing Li, Jong Keun Park, Robert B. Moore and Louis A. Madsen
doi:10.1038/nmat3048
Polymer electrolyte membranes selectively transport ions and polar molecules, and are of interest for applications such as polymeric batteries, fuel cells, mechanical actuators and water purification. Transport anisotropy is now shown to linearly depend on the degree of alignment, indicating that membrane stretching only causes domain reorientation without affecting channel dimensions or defect structure.
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See also: News and Views by Samulski

Articles

Structural origin of enhanced slow dynamics near a wall in glass-forming systems pp512 - 520
Keiji Watanabe, Takeshi Kawasaki and Hajime Tanaka
doi:10.1038/nmat3034
Container walls are known to have a significant influence on the dynamics of glass formation. Computations now suggest that structural order is the origin of the slower dynamics of a glass-forming liquid near container walls.
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Giant Rashba-type spin splitting in bulk BiTeI pp521 - 526
K. Ishizaka, M. S. Bahramy, H. Murakawa, M. Sakano, T. Shimojima, T. Sonobe, K. Koizumi, S. Shin, H. Miyahara, A. Kimura, K. Miyamoto, T. Okuda, H. Namatame, M. Taniguchi, R. Arita, N. Nagaosa, K. Kobayashi, Y. Murakami, R. Kumai, Y. Kaneko, Y. Onose and Y. Tokura
doi:10.1038/nmat3051
A very large Rashba-type spin splitting, which is a consequence of spin–orbit interaction, has been observed in the heavy-element semiconductor BiTeI. The results show the possibility, in principle, of using the material in spintronics devices in which the electron spin is controlled by electric currents.
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Giant enhancement of spin accumulation and long-distance spin precession in metallic lateral spin valves pp527 - 531
Yasuhiro Fukuma, Le Wang, Hiroshi Idzuchi, Saburo Takahashi, Sadamichi Maekawa and YoshiChika Otani
doi:10.1038/nmat3046
Pure spin current—the flow of spin angular momentum involving no charge movement—could lead to highly efficient spintronic devices. It is now shown that through low-resistivity magnetic tunnelling junctions it is possible to induce spin accumulation in solid-state devices one hundred times higher than previously obtained. This is the main requirement for generation of large spin currents.
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High-performance flat-panel solar thermoelectric generators with high thermal concentration pp532 - 538
Daniel Kraemer, Bed Poudel, Hsien-Ping Feng, J. Christopher Caylor, Bo Yu, Xiao Yan, Yi Ma, Xiaowei Wang, Dezhi Wang, Andrew Muto, Kenneth McEnaney, Matteo Chiesa, Zhifeng Ren and Gang Chen
doi:10.1038/nmat3013
The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. A highly efficient solar to electric energy conversion device based on nanostructured thermoelectric materials and high solar concentration is now demonstrated. The results show potential for cost effective solar thermoelectric generation.
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See also: News and Views by Karni

Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation pp539 - 544
Yi Wei Chen, Jonathan D. Prange, Simon Dühnen, Yohan Park, Marika Gunji, Christopher E. D. Chidsey and Paul C. McIntyre
doi:10.1038/nmat3047
Electrochemical energy can be produced by using solar energy to oxidize water, providing an abundant source of electrons, which are needed in fuel synthesis. The operation of an efficient and stable semiconductor nanocomposite anode, made of a protective TiO₂ layer that protects a silicon substrate during photoelectrochemical water oxidation in both dark and light conditions, is now reported.
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Nanoparticles that communicate in vivo to amplify tumour targeting pp545 - 552
Geoffrey von Maltzahn, Ji-Ho Park, Kevin Y. Lin, Neetu Singh, Christian Schwöppe, Rolf Mesters, Wolfgang E. Berdel, Erkki Ruoslahti, Michael J. Sailor and Sangeeta N. Bhatia
doi:10.1038/nmat3049
A two-component nanoparticle system that communicates and enhances in vivo drug delivery and diagnostics has been devised. The system comprises ‘signalling’ nanoparticles that target tumours and then broadcast the tumour’s location to ’receiving’ nanoparticles in circulation, which carry therapeutic or diagnostic cargos, hence amplifying tumour targeting.
Abstract | Full Text | PDF
See also: News and Views by Wang et al.