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Colloidal PbS/PbCl2 core/shell nanoplatelets were synthesized via wet-chemical methods using lead oleate and lead chloride as lead precursors. The resulting heterostructures consist of a PbS core, a PbCl2 shell, and an intermediate layer of lead sulfochloride alloy. These nanoplatelets exhibit a photoluminescence quantum yield of approximately 20%, nearly an order of magnitude higher than that of unshelled PbS nanoplatelets. Cyclic voltammetry measurements reveal a type-I band alignment between the core and shell. Despite the presence of strong attractive biexciton Auger recombination, as observed in transient absorption spectroscopy, the nanoplatelets achieve amplified spontaneous emission at a low pump threshold of 76 μJ cm–2. Their large lateral dimensions support the spatial distribution of multiple excitons, including repulsive biexcitons, enabling efficient light amplification. 

Mechanical metamaterials have recently been exploited as an interesting platform for information storing, retrieval and processing, analogous to electronic devices. In this work, we describe the design and fabrication a two-dimensional (2D) multistable metamaterial consisting of building blocks that can be switched between two distinct stable phases, and which are capable of storing binary information analogous to digital bits. By changing the spatial distribution of the phases, we can achieve a variety of different configurations and tunable mechanical properties (both static and dynamic). Moreover, we demonstrate the ability to determine the phase distribution via simple probing of the dynamic properties, to which we refer as mechanical proprioception. Finally, as a simple demonstration of feasibility, we illustrate a strategy for building autonomous kirigami systems that can receive inputs from their environment. This work could bring new insights for the design of mechanical metamaterials with information processing and computing functionalities. This article is part of the theme issue ‘Origami/Kirigami-inspired structures: from fundamentals to applications’. 

Abstract In recent years, mechanical metamaterials have been developed that support the propagation of an intriguing variety of nonlinear waves, including transition waves and vector solitons (solitons with coupling between multiple degrees of freedom). Here we report observations of phase transitions in 2D multistable mechanical metamaterials that are initiated by collisions of soliton-like pulses in the metamaterial. Analogous to first-order phase transitions in crystalline solids, we observe that the multistable metamaterials support phase transitions if the new phase meets or exceeds a critical nucleus size. If this criterion is met, the new phase subsequently propagates in the form of transition waves, converting the rest of the metamaterial to the new phase. More interestingly, we numerically show, using an experimentally validated model, that the critical nucleus can be formed via collisions of soliton-like pulses. Moreover, the rich direction-dependent behavior of the nonlinear pulses enables control of the location of nucleation and the spatio-temporal shape of the growing phase. 

Abstract BackgroundNutrient availability is among the most widespread means by which environmental variability affects developmental outcomes. Because almost all cells within an individual organism share the same genome, structure-specific growth responses must result from changes in gene regulation. Earlier work suggested thathistone deacetylases(HDACs) may serve as epigenetic regulators linking nutritional conditions to trait-specific development. Here we expand on this work by assessing the function of diverseHDACsin the structure-specific growth of both sex-shared and sex-specific traits including evolutionarily novel structures in the horned dung beetleOnthophagus taurus. ResultsWe identified fiveHDACmembers whose downregulation yielded highly variable mortality depending on whichHDACmember was targeted. We then show thatHDAC1,3, and4operate in both a gene- and trait-specific manner in the regulation of nutrition-responsiveness of appendage size and shape. Specifically,HDAC 1, 3,or4knockdown diminished wing size similarly while leg development was differentially affected by RNAi targetingHDAC3andHDAC4. In addition, depletion ofHDAC3transcript resulted in a more rounded shape of genitalia at the pupal stage and decreased the length of adult aedeagus across all body sizes. Most importantly, we find thatHDAC3andHDAC4pattern the morphology and regulate the scaling of evolutionarily novel head and thoracic horns as a function of nutritional variation. ConclusionCollectively, our results suggest that both functional overlap and division of labor amongHDACmembers contribute to morphological diversification of both conventional and recently evolved appendages. More generally, our work raises the possibility thatHDAC-mediated scaling relationships and their evolution may underpin morphological diversification within and across insect species broadly. 

Pneumatic soft robots have several advantages, including facile fabrication, versatile deformation modes, and safe human–machine interaction. However, pneumatic soft robots typically rely on mechatronics to interact with their environment, which can limit their form factors and reliability. Researchers have considered how to achieve autonomous behaviors using the principles of mechanical computing and physical intelligence. Herein, modular responsive valves that can autonomously regulate airflow within pneumatic soft robots in response to various environmental stimuli, including light, water, and mechanical forces, are described. By combining multiple types of valves, autonomous logic gates and more advanced logical operations can be realized. Finally, it is demonstrated that responsive valves can be integrated with pneumatic soft robots, allowing autonomous morphing and navigation. This framework provides a strategy for creating autonomous pneumatic robots that can respond to multiple stimuli in their environment. 

Abstract Aryl fluorosulfates of varying complexities have been used in amination reactions in water using a new Pd oxidative addition complex (OAC‐1) developed specifically to match the needs of the fine chemicals industry, not only in terms of functional group tolerance, but also reflecting time considerations associated with these important C−N couplings. Also especially noteworthy is that they replace both PFAS‐related triflates and nonaflates, which are today out of favor due to recent government regulations. The new complex based on the BippyPhos ligand is used at low loadings and under aqueous micellar conditions. Moreover, it is easily prepared and stable to long term storage. DFT calculations on the OAC precatalyst compare well with the X‐ray structure of the crystals with π‐complexation to the aromatic system of the ligand and also confirm the NMR data showing a mixture of conformers in solution that differ from the X‐ray structure in rotation of the phenyl andt‐butyl ligand substituents. An extensive variety of coupling partners, including pharmaceutically relevant APIs, readily participate under mild and environmentally responsible reaction conditions.