Explore the vast range of titles available.

Rapid energy‐efficient movements are one of nature's greatest developments. Mechanisms like snap‐buckling allow plants like the Venus flytrap to close the terminal lobes of their leaves at barely perceptible speed. Here, a soft balloon actuator is presented, which is inspired by such mechanical instabilities and creates safe, giant, and fast deformations. The basic design comprises two inflated elastomer membranes pneumatically coupled by a pressurized chamber of suitable volume. The high‐speed actuation of a rubber balloon in a state close to the verge of mechanical instability is remotely triggered by a voltage‐controlled dielectric elastomer membrane. This method spatially separates electrically active and passive parts, and thereby averts electrical breakdown resulting from the drastic thinning of an electroactive membrane during large expansion. Bistable operation with small and large volumes of the rubber balloon is demonstrated, achieving large volume changes of 1398% and a high‐speed area change rate of 2600 cm2 s−1. The presented combination of fast response time with large deformation and safe handling are central aspects for a new generation of soft bio‐inspired robots and can help pave the way for applications ranging from haptic displays to soft grippers and high‐speed sorting machines. A voltage‐triggered soft balloon actuator with an impressive displacement (1398% total volume change) at high speed (2600 cm2 s−1 area change rate) is developed by harnessing the mechanical snap‐through and snap‐back instability of a rubber balloon. The trigger actuator is pneumatically coupled to the high‐speed actuator. This concept promises applications in soft bio‐inspired systems in modern robotics and engineering.

Fast snapping in the carnivorous Venus flytrap (Dionaea muscipula) involves trap lobe bending and abrupt curvature inversion (snap‐buckling), but how do these traps reopen? Here, the trap reopening mechanics in two different D. muscipula clones, producing normal‐sized (N traps, max. ≈3 cm in length) and large traps (L traps, max. ≈4.5 cm in length) are investigated. Time‐lapse experiments reveal that both N and L traps can reopen by smooth and continuous outward lobe bending, but only L traps can undergo smooth bending followed by a much faster snap‐through of the lobes. Additionally, L traps can reopen asynchronously, with one of the lobes moving before the other. This study challenges the current consensus on trap reopening, which describes it as a slow, smooth process driven by hydraulics and cell growth and/or expansion. Based on the results gained via three‐dimensional digital image correlation (3D‐DIC), morphological and mechanical investigations, the differences in trap reopening are proposed to stem from a combination of size and slenderness of individual traps. This study elucidates trap reopening processes in the (in)famous Dionaea snap traps – unique shape‐shifting structures of great interest for plant biomechanics, functional morphology, and applications in biomimetics, i.e., soft robotics. The snap traps of the infamous Venus flytrap have remarkable shape‐shifting capabilities. After fast snapping in an attempt to capture prey, the traps can slowly reopen via two modes of sequential deformation. Whereas normal‐sized traps (N traps) reopen smoothly and continuously via hydraulic processes alone, large and slender traps (L traps) can incorporate an additional reverse snap‐buckling instability during reopening.

Many species of nightjar reportedly produce short, impulsive wing sounds during courtship, but the kinematics and physical mechanisms of sound production remain speculative. Using synchronized infrared high‐speed video and audio recordings we describe the mechanism of sound production of a sonation in the nocturnal family Caprimulgidae; the wing‐snapping of male scissor‐tailed nightjars Hydropsalis torquata . This sound is a short, sharp, loud, ‘ tk ', produced singly in a jump display (jump snap), in a syncopated series during a flight display (flying snaps), and in a fast series during copulation (copulation snaps). To produce these ‘ tk ' sounds, males rapidly elevated and supinated the wings to slam opposing wrists together. The videos falsify the hypotheses that sound is produced by intra‐ or inter‐wing colliding feathers or by clapping (i.e. a pulse of air accelerating to escape a constricted space, as in human hand‐clapping), as there was no contact by the surface of opposing wing‐feathers. Instead, the physical acoustic mechanism appears to be impulsive collisions between the wing bones (radii) which then vibrate, like wing‐snapping of Manacus manakins. A low‐frequency mechanical thud , produced by an unknown intra‐wing mechanism during the downstroke is also present in flying snaps and copulation snaps , and occurs independently during fast takeoff. Fluffle was produced by feathers rustling and colliding in preen‐like behavior that has likely a communicative function. An additional male display, the wing rattle , made in flight during chases, has a complex acoustic structure including a similar yet distinct mechanical impulsive sound, the thud , a whoosh, and vocal sounds, indicating a suite of possible sound production mechanisms. The wings seemingly do not touch during the wing‐rattle , suggesting that the second type of impulsive sound is produced by intra‐wing feather collisions. Preliminary comparisons indicate the conservation of homologous sound‐producing mechanisms and sounds in New World nightjars.

Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are a family of small conserved eukaryotic proteins that mediate membrane fusion between organelles and with the plasma membrane. SNAREs are directly or indirectly anchored to membranes. Prior to fusion, complementary SNAREs assemble between membranes with the aid of accessory proteins that provide a scaffold to initiate SNARE zippering, pulling the membranes together and mediating fusion. Recent advances have enabled the construction of detailed models describing bilayer transitions and energy barriers along the fusion pathway and have elucidated the structures of SNAREs complexed in various states with regulatory proteins. In this Review, we discuss how these advances are yielding an increasingly detailed picture of the SNARE-mediated fusion pathway, leading from first contact between the membranes via metastable non-bilayer intermediates towards the opening and expansion of a fusion pore. We describe how SNARE proteins assemble into complexes, how this assembly is regulated by accessory proteins and how SNARE complexes overcome the free energy barriers that prevent spontaneous membrane fusion.Eukaryotic membrane fusion is hindered by energy barriers and often requires soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) to facilitate formation of a fusion pore. Recent studies describe SNARE activity along the fusion pathway and shed light on the regulation of SNARE complex assembly.

Soft, inflatable segments are the active elements responsible for the actuation of soft machines and robots. Although current designs of fluidic actuators achieve motion with large amplitudes, they require large amounts of supplied volume, limiting their speed and compactness. To circumvent these limitations, here we embrace instabilities and show that they can be exploited to amplify the response of the system. By combining experimental and numerical tools we design and construct fluidic actuators in which snap-through instabilities are harnessed to generate large motion, high forces, and fast actuation at constant volume. Our study opens avenues for the design of the next generation of soft actuators and robots in which small amounts of volume are sufficient to achieve significant ranges of motion.

This paper discusses a full interferometry processing chain based on dual-orbit Sentinel-1A and Sentinel-1B (S1) synthetic aperture radar data and a combination of open-source routines from the Sentinel Application Platform (SNAP), Stanford Method for Persistent Scatterers (StaMPS), and additional routines introduced by the authors. These are used to provide vertical and East-West horizontal velocity maps over a study area in the south-western sector of the Po Plain (Italy) where land subsidence is recognized. The processing of long time series of displacements from a cluster of continuous global navigation satellite system stations is used to provide a global reference frame for line-of-sight–projected velocities and to validate velocity maps after the decomposition analysis. We thus introduce the main theoretical aspects related to error propagation analysis for the proposed methodology and provide the level of uncertainty of the validation analysis at relevant points. The combined SNAP–StaMPS workflow is shown to be a reliable tool for S1 data processing. Based on the validation procedure, the workflow allows decomposed velocity maps to be obtained with an accuracy of 2 mm/yr with expected uncertainty levels lower than 2 mm/yr. Slant-oriented and decomposed velocity maps provide new insights into the ground deformation phenomena that affect the study area arising from a combination of natural and anthropogenic sources.

Snap‐through instability, a rapid transition between equilibrium states, has emerged as a crucial mechanism for designing mechanical metamaterials with novel functionalities, including fast motion, energy modulation, and bistable deformation. Metamaterials with snap‐through instability, known as snapping metamaterials, have enabled diverse applications, such as robotics, sensing, energy absorption, shape reconfiguration, and mechanical intelligence. Given the importance of these advancements, a comprehensive review of this field is highly desired. This paper provides an overview of recent research on snapping metamaterials, focusing on their design strategies and applications. Here, we summarized snapping metamaterials in several respects, including beam‐based structures, shell‐based structures, and origami/kirigami designs, according to their basic elements, alongside a brief discussion of their unique deformation mechanisms. Furthermore, the potential applications of snapping metamaterials are presented in terms of motion, energy, and deformation. To conclude, perspectives on the challenges and opportunities in this emerging field are highlighted, offering insights into the future research and development of snapping metamaterials. The review explores the structural designs and deformation mechanisms of mechanical metamaterials with snap‐through instability. It discusses recent advancements in their applications, focusing on unique functionalities in motion, energy, and deformation. Furthermore, the paper provides insights into future challenges and opportunities in this emerging field.

Single-cell RNA sequencing can reveal the transcriptional state of cells, yet provides little insight into the upstream regulatory landscape associated with open or accessible chromatin regions. Joint profiling of accessible chromatin and RNA within the same cells would permit direct matching of transcriptional regulation to its outputs. Here, we describe droplet-based single-nucleus chromatin accessibility and mRNA expression sequencing (SNARE-seq), a method that can link a cell’s transcriptome with its accessible chromatin for sequencing at scale. Specifically, accessible sites are captured by Tn5 transposase in permeabilized nuclei to permit, within many droplets in parallel, DNA barcode tagging together with the mRNA molecules from the same cells. To demonstrate the utility of SNARE-seq, we generated joint profiles of 5,081 and 10,309 cells from neonatal and adult mouse cerebral cortices, respectively. We reconstructed the transcriptome and epigenetic landscapes of major and rare cell types, uncovered lineage-specific accessible sites, especially for low-abundance cells, and connected the dynamics of promoter accessibility with transcription level during neurogenesis. SNARE-seq measures expression profiles and chromatin accessibility in the same cell.

Little is known about the biological roles of glycosylated RNAs (glycoRNAs), a recently discovered class of glycosylated molecules, because of a lack of visualization methods. We report sialic acid aptamer and RNA in situ hybridization-mediated proximity ligation assay (ARPLA) to visualize glycoRNAs in single cells with high sensitivity and selectivity. The signal output of ARPLA occurs only when dual recognition of a glycan and an RNA triggers in situ ligation, followed by rolling circle amplification of a complementary DNA, which generates a fluorescent signal by binding fluorophore-labeled oligonucleotides. Using ARPLA, we detect spatial distributions of glycoRNAs on the cell surface and their colocalization with lipid rafts as well as the intracellular trafficking of glycoRNAs through SNARE protein-mediated secretory exocytosis. Studies in breast cell lines suggest that surface glycoRNA is inversely associated with tumor malignancy and metastasis. Investigation of the relationship between glycoRNAs and monocyte–endothelial cell interactions suggests that glycoRNAs may mediate cell–cell interactions during the immune response. GlycoRNA imaging in cells is enabled with a proximity ligation assay.