Research articles

Molecular switches regulate many fundamental processes in natural and artificial systems. An electrochemical platform in which a proton carrier switches the activity of a catalyst is now presented. A hybrid bilayer membrane allows the regulation of proton transport to a Cu-based molecular oxygen reduction reaction catalyst.

Cerium hexaboride is a canonical heavy-fermion system that has come under scrutiny because of its so-called hidden order phase. Now, detailed inelastic neutron scattering experiments reveal an intense ferromagnetic mode, thus overturning the generally accepted view that antiferromagnetic interactions dominate the low-temperature behaviour of this system.

Enzymes involved in copper metabolism and residing within bacterial outer layers are used to polymerize monomers bound to the bacterial cell surface. The composition of the polymers is affected by templating processes and hence the polymers are specific binding agents for the bacteria on which they are grown.

The energy interaction between different exciton species is affected by the optical environment in which they are embedded. It is now shown that mixed exciton–polariton states in strongly coupled microcavities can facilitate energy transfer between organic dyes at length scales greater than the Förster transfer radius.

Cell behaviour is in part regulated by the rigidity of their environment, yet the underlying mechanisms have remained unclear. It is now shown for breast myoepithelial cells expressing two types of integrin that rigidity sensing and adaptation can be explained by a clutch-bond model that considers the different rates of binding and unbinding between the integrins and the extracellular matrix.

Trilayer graphene can be realized in two different stacking configurations, known as rhombohedral and Bernal stackings, which display different electronic characteristics. It is now shown that an applied perpendicular electric field can be used to switch between these two configurations.

Heterostructures consisting of ferromagnets and heavy metals have become a focus of interest because their strong spin–orbit coupling allows for efficient current-induced magnetization switching phenomena. Now, a magnetically doped topological insulator bilayer is shown to display a range of appealing characteristics for current-induced magnetization switching, including a significantly enhanced efficiency.

A strategy to overcome the maximum theoretical efficiency limit of single-junction solar cells is to realize stacked, multi-junction cells that are used under highly concentrated light. Now, a printing-based, scalable approach for the assembly of multi-junction solar cells in concentrator photovoltaic modules that reach a high power conversion efficiency is reported.

Fano resonances have been studied for many resonant optical systems. To fully understand the origin behind this phenomenon it would be necessary to have simultaneous information about the dissipation of stored energy in the near-field and the scattering response in the far-field. This is now shown to be possible in a single semiconductor nanostripe using photocurrent measurements.

Methods to achieve large-scale production of defect-free graphene are needed to enable the commercial development of graphene-based devices. It is now shown that high-shear mixing is an effective way to exfoliate graphene and other two-dimensional materials in liquid volumes up to hundreds of litres.

When exiting pluripotency but before irreversibly committing, embryonic stem cells pass through at least one transition state. It is now shown that in this metastable state the nuclei of the cells is auxetic, that is, when stretched their cross-section expands, and when compressed their cross-section contracts, and that this is in part a consequence from global chromatin de-condensation.

A number of rare-earth pyrochlore materials are experimental realizations of spin ice, a magnetic state that shares a number of similarities with conventional water ice. Diffuse neutron scattering experiments now show that oxygen vacancies strongly affect the dynamics of monopole excitations in the spin-ice material Y₂Ti₂O_7−δ.

For metallic glasses composed of three or more elements, optimizing their composition to satisfy a combination of properties is a formidable task. Now, a high-throughput strategy that can simultaneously fabricate thousands of alloy compositions and characterize them for thermoplastic formability through parallel blow forming makes possible the identification of the alloy composition with the highest thermoplastic formability.

Although human pluripotent stem cells (hPSCs) can be used to regenerate neural tissues, inefficient protocols and poorly defined culture conditions have hindered their use. It is now shown that soft, micropatterned culture substrates can induce hPSCs to differentiate into motor neurons with significantly improved yields and purity in comparison to rigid substrates, and that such mechanotransductive process involves the Hippo/YAP pathway and phosphorylation of the intracellular protein Smad.

The use of encoded microparticles in industrial settings is hampered by issues of scalability, decoding robustness and encoding density. Now, easily decodable microparticles with spatially patterned rare-earth upconversion nanocrystals, exponentially scalable encoding capacities and ultralow decoding false-alarm rates that are insensitive to harsh processing environments and can be used in practical applications such as durable anti-counterfeiting labels and multiplexed bioassays are reported.

Self-assembled nanoparticle superlattices, which consist of inorganic cores capped by organic ligands, can show emergent behaviour as a result of the coupling between their nanoscale components. The atom-level structure of a silver nanoparticle superlattice, deduced from X-ray imaging and simulations, is now reported as well as its response to hydrostatic compression, which involves anomalous pressure softening and correlated chiral rotation of the nanoparticles.

The valley degree of freedom has been proposed as a means to encode information in a number of condensed-matter systems. Now, detailed scanning tunnelling microscopy measurements are used to spatially resolve the valleys associated with a single donor qubit in silicon.

In addition to the structural chirality of materials, there has recently been a rise in interest in the chirality arising from their magnetic and electronic structure. Using a spatially resolved resonant X-ray diffraction technique, a helical arrangement of the Dy 4f quadrupole moments in the ferroborate system DyFe₃(BO₃)₄ is uncovered.

To ensure survival, the exoskeletons of biological species are required to minimize the spatial extent of damage following attack or multi-hit events. Now, nanoindentation experiments on a transparent bivalve shell, which is made up of layered, diamond-shaped calcite crystals, show an increased energy dissipation density compared with single-crystal calcite, resulting in penetration resistance and deformation localization. The detailed mechanisms of this enhanced energy dissipation are revealed and include nanoscale deformation twinning around the penetration zone.

Excessive activity of matrix metalloproteinases (MMPs) occurs in many diseases; however, the systemic administration of MMP inhibitors can cause undesirable, off-target effects and hence, clinical translation has been hampered. Now, injectable polysaccharide-based hydrogels are shown to enable the localized delivery of an inhibitor of MMP following the hydrogels’ degradation in response to MMP activity. This targeted approach shows efficacy in a myocardial infarction model in large animals.