Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
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 Y2Ti2O7−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.
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.
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.
Strontium titanate is widely studied for the myriad of phenomena that are known to occur in the vicinity of its surface. It is now shown that light can be used to induce magnetism in oxygen-deficient crystals of SrTiO3.
The toughness of ceramic materials can be improved by introducing a polymeric or metallic ductile phase, yet most often this is at the expense of strength, stiffness and high-temperature stability. Now, a simple processing route based on widespread ceramic processing techniques is shown to produce bulk ceramics that mimic the structure of natural nacre and have a unique combination of high strength, toughness and stiffness, even at high temperatures.
Biofilms are multifunctional and environmentally responsive assemblies of living and non-living components. By using synthetic gene networks in engineered cells to regulate the production of extracellular amyloid fibrils, and by interfacing the fibrils with inorganic materials such as metal nanoparticles, stimuli-responsive synthetic biofilms with switchable functions and tunable composition and structure have now been produced.
Quantum spin liquids are a state of magnetic order that, in analogy with ordinary liquids, is characterized by fluctuating, disordered spins. By means of specific heat measurements, the frustrated Kondo system Pr2Ir2O7 is shown to undergo a transition to such a state in zero magnetic field.
Optical amplifiers based on erbium ions typically require high pump power densities to produce gain. Now, an organic optical amplifier material composed of erbium ions and a zinc-based organic chromophore is demonstrated to reach population inversion using low-power visible light.
The use of persistent luminescence nanoparticles for in vivo optical imaging commonly requires ex vivo activation before systemic administration, hampering longer-term imaging capabilities. Now, it is shown that near-infrared emitting nanoprobes based on chromium-doped zinc gallate can be activated in vivo using low-energy red light and used for tumour-targeted imaging and cell tracking experiments.
The energy density of supercapacitors can be enhanced by using ionic liquids and electrodes with subnanometre pores, but this tends to reduce their power density. The mechanisms of charging subnanometre pores with ionic liquids are now clarified and molecular simulations suggest that charging of such ionophilic pores is a diffusive process.
Mechanical cues from the local cellular microenvironment can direct cell fate. Now, experiments with human mesenchymal stem cells cultured on phototunable soft poly(ethylene glycol) hydrogels show that the cells remember past physical environments—with the transcriptional co-activators YAP and TAZ acting as a mechanical rheostat—and therefore that appropriate doses of mechanical cues can be used to manipulate the cells’ fate.
Imparting non-native functions to living plants using nanoparticles opens the possibility of creating synthetic materials that can grow and repair themselves using sunlight, water and carbon dioxide. It is now shown that, both in plant extracts and living leaves, carbon nanotubes traverse and localize within the lipid envelope of plant chloroplasts, enhance their photosynthetic activity, and enable near-infrared fluorescence monitoring of nitric oxide.
Although dispersions of aligned graphene oxide flakes are particularly attractive for electro-optic devices, controlling the alignment of the flakes by using electric fields has proved difficult. It is now shown that the macroscopic alignment of graphene oxide liquid crystals can be controlled through the application of weak electric fields when interflake interactions are sufficiently small, giving rise to the largest Kerr coefficient in a molecular liquid crystal.
Cuprate superconductors have found limited application for high-field magnets because of difficulties related to grain boundaries. Now, this issue is partially overcome and round wires suitable for magnetic coils are fabricated from Bi2Sr2CaCu2O8−x.
The collective migration of epithelial cells arises from the interplay between intercellular forces and cellular signalling networks. It is now shown that the migration of an epithelium can be controlled by applying electric fields that bias the signalling networks, and that such galvanotactic control can prompt cell populations to make coordinated U-turns, undergo divergent or convergent migration, or move against an obstacle.
