The electrochemical reduction of oxygen to hydrogen peroxide requires selective and stable electrocatalysts. Using density functional theory calculations Pt–Hg has been identified as a promising candidate. It is now shown that Pt–Hg nanoparticles display an order of magnitude improvement in the mass activity for H2O2 production compared with the best performing catalyst.

Article p1137

IMAGE: ARNAU VERDAGUER-CASADEVALL AND MOHAMMADREZA KARAMAD

COVER DESIGN: DAVID SHAND

The nonlinear response of a weak electrolyte to an applied electric field is known as the Wien effect. This is now simulated on a lattice Coulomb gas, therefore providing a platform for investigating system-specific corrections to the firmly established theory accounting for it.

Letter p1033

IMAGE: VOJTECH KAISER

COVER DESIGN: DAVID SHAND

Hard biological materials such as diatoms and sea sponges can inspire the design of structural materials that are mechanically robust yet lightweight. Hollow titanium nitride lattices have now been fabricated that mimic the length scales (from 10 nm to 100 μm) and hierarchy of biological materials. These lattices attain tensile strengths of 1.75 GPa without failing (even after multiple deformation cycles) because of the low probability of pre-existing flaws.

Letter p893

IMAGE: LUCAS MEZA

COVER DESIGN: DAVID SHAND

Although the collective cellular motion involved in, for example, wound healing and tumour invasion is suspected to be driven by mechanical stresses within the advancing cell monolayer, how motion and stress relate has remained elusive. Now, stress-microscopy observations of an epithelial cell sheet advancing towards a region where cells cannot adhere reveal that the cells located nearby such a region exert forces that pull them towards the unfilled space, regardless of whether the cells approach or recede from it.

Article p856; News & Views p783

IMAGE: XAVIER SERRA-PICAMAL AND XAVIER TREPAT

COVER DESIGN: DAVID SHAND

At present, there are no known examples of binary icosahedral quasicrystals featuring localized magnetic moments. Now, a family of magnetic binary icosahedral quasicrystals is discovered, offering the possibility of studying the behaviour of coupled magnetic interactions in the presence of aperiodic structural order.

Letter p714; News & Views p692

IMAGE: A. KREYSSIG, M. RAMAZANOGLU, T. KONG, A. JESCHE, D. K. PRATT, G. S. TUCKER, A. SAPKOTA, S. L. BUD'KO, P. C. CANFIELD AND A. I. GOLDMAN/AMES LABORATORY, US DOE AND IOWA STATE UNIV.

COVER DESIGN: DAVID SHAND

Solution printing of organic semiconductors could in principle be scaled to industrial needs, yet attaining aligned single-crystals directly with this method has been challenging. By using a micropillarpatterned printing blade designed to enhance the control of crystal nucleation and growth, thin films of macroscopic, highly aligned single crystals of organic semiconductors can now be fabricated.

Article p665; News & Views p598

IMAGE: ZHENAN BAO AND YING DIAO

COVER DESIGN: DAVID SHAND

Analytical techniques reveal that spherical calcium phosphate particles are the first mineralized structures to be formed in the calcification process in cardiovascular tissues. Furthermore, the inner sections of calcified lesions in patients with various cardiovascular diseases are identified as highly crystalline, spherical hydroxyapatite particles that differ in structure from bone mineral.

Article p576; News & Views p476

IMAGE: S. BERTAZZO, DEPT. OF MATERIALS, IMPERIAL COLLEGE LONDON

COVER DESIGN: DAVID SHAND

Much less exploited than the spectral and spatial properties of surface plasmons (SPs) are their local density of states (SP-LDOS), which rule a number of important nanoscale phenomena. Using two-photon luminescence microscopy, the SP-LDOS in ultrathin gold nanoprisms is now visualized directly, allowing for the SP modal distribution to be tuned.

Article p426; News & Views p380

IMAGE: E. DUJARDIN, CEMES CNRS

COVER DESIGN: DAVID SHAND

Controlling the charge and spin states of single molecular complexes at metal interfaces is a challenging task. Scanning tunnelling microscopy experiments now show that doping metal phthalocyanines with alkali ions is an effective way to achieve this.

Article p337

IMAGE: A. MUGARZA, C. KRULL AND P. GAMBARDELLA, CATALAN INSTITUTE OF NANOTECHNOLOGY (ICN)

COVER DESIGN: DAVID SHAND

The monitoring of cell survival and functionality following their in vivo transplantation remains a challenge in clinical cell therapy. Now, using magnetic resonance imaging techniques and microcapsules with pH-sensitive components, in vivo cell death and cell viability patterns can be assessed with high anatomical accuracy.

Article p268; News & Views p180

IMAGE: NICOLLE FULLER, SAYO-ART

A critical component for chip-scale integrated photonics would be a non-reciprocal optical waveguide allowing light to travel in only one direction while reflecting it in the opposite one. Inspired by concepts of parity-time-symmetric quantum theories and built on a silicon on-insulator platform using only absorptive media, a periodically modulated dielectric waveguide exhibiting unidirectional reflection has now been demonstrated, reflecting light at telecom frequencies in only one direction with a high contrast ratio.

Letter p108

IMAGE: LIANG FENG, CALIFORNIA INSTITUTE OF TECHNOLOGY; MING-HUI LU, NANJING UNIVERSITY

COVER DESIGN: DAVID SHAND

Gathering information on the evolution of small cracks in ceramic matrix composites used in hostile environments such as in gas turbines and hypersonic flights has been a challenge. It is now shown that sequences of microcrack damage in ceramic composites under load at temperatures up to 1,750 °C can be fully resolved with the use of in situ synchrotron X-ray computed microtomography.

Article p40; News & Views p7

IMAGE: HRISHIKESH A. BALE

COVER DESIGN: DAVID SHAND