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Numerous studies have shown flexible electronics play important roles in health management. The way of power supply is always an essential factor of devices and self-powered ones are very attractive because of the fabrication easiness, usage comfort and aesthetics of the system. In this work, based on the metal-air redox reaction, which is usually used in designing metal-air batteries, we design a self-powered chemoelectric humidity sensor where a silk fibroin (SF) and LiBr gel matrix containing parallel aligned graphene oxide (GO) flakes serve as the electrolyte. The abundant hydrophilic groups in GO/SF and the hygroscopicity of LiBr lead to tight dependence of the output current on the humidity, enabling the sensor high sensitivity (0.09 μA/s/1%), fast response (1.05 s) and quick recovery (0.80 s). As proofs of concept, we design an all-in-one respiratory monitoring-diagnosing-treatment system and a non-contact human-machine interface, demonstrating the applications of the chemoelectric humidity sensor in health management. Self-powered sensors are of interest in wearable technology and other applications. Here, the authors report on the creation of a metal-air redox reaction humidity sensor where the conductance and charge generated is influenced by the amount of absorbed water and demonstrate application in respiration monitoring.

In recent years, with the access of high-speed broadband, the number of videos on online sharing platforms has increased sharply, and the copyright protection of videos has been widely concerned. However, existing block-based watermarking methods have high sensitivity under geometric deformation and cannot accurately locate the watermark position, which leads to the failure of watermark extraction. Therefore, a robust and blind video watermarking scheme to resist the online sharing platform is proposed. Firstly, DTCWT is used to preprocess the video to reduce the influence of non-geometric signals on the extracted watermark. Secondly, the low frequency domain is divided into rings of different sizes, and the spatial stability region is established to ensure the synchronization of watermark extraction. Finally, the energy of the ring subband is obtained by DCT on the ring, and the watermark embedding is optimized by adjusting the energy relationship of adjacent energy rings to balance the invisibility and robustness of the watermark using the strong correlation of adjacent video frames. The experimental results show that the proposed watermarking scheme can not only resist common video processing operations, but also show good robustness to video online sharing platforms.

Biologically derived and biologically inspired fibers with outstanding mechanical properties have found attractive technical applications across diverse fields. Despite recent advances, few fibers can simultaneously possess high-extensibility and self-recovery properties especially under wet conditions. Here, we report protein-based fibers made from recombinant scallop byssal proteins with outstanding extensibility and self-recovery properties. We initially investigated the mechanical properties of the native byssal thread taken from scallop Chlamys farreri and reveal its high extensibility (327 ± 32%) that outperforms most natural biological fibers. Combining transcriptome and proteomics, we select the most abundant scallop byssal protein type 5-2 (Sbp5-2) in the thread region, and produce a recombinant protein consisting of 7 tandem repeat motifs (rTRM7) of the Sbp5-2 protein. Applying an organic solvent-enabled drawing process, we produce bio-inspired extensible rTRM7 fiber with high-extensibility (234 ± 35%) and self-recovery capability in wet condition, recapitulating the hierarchical structure and mechanical properties of the native scallop byssal thread. We further show that the mechanical properties of rTRM7 fiber are highly regulated by hydrogen bonding and intermolecular crosslinking formed through disulfide bond and metal-carboxyl coordination. With its outstanding mechanical properties, rTRM7 fiber can also be seamlessly integrated with graphene to create motion sensors and electrophysiological signal transmission electrode. Bio-inspired materials are an intense area of study as researchers try to adapt biomaterials for other applications. Here, the authors report on the processing of protein materials derived from the byssal thread of scallops to create high-extensibility materials with self-recovery under wet conditions.

Carbon nanotubes (CNTs) hold great promise in many fields because of their unique structures and properties. However, the preparation of CNTs generally involves cumbersome equipment and time-consuming processes. Here, we report an ultra-fast carbothermal shock (CTS) approach for synthesizing CNTs with a simple homemade setup by employing Joule heating of a carbon substrate. Carbonized silk fabric (CSF) loaded with transition metal salts in ethanol solution was used as the substrate, which was treated with a pulse voltage of 40 V for only 50 ms and then covered with uniform CNTs grown with bimetallic alloy catalyst nanoparticles (diameter: ∼ 9 nm). The temperature ramp rate is as high as 10 5 K/s. The as-obtained sample has a unique fluffy structure similar to the trichobothrium of spiders, endowing it versatile applications such as airflow sensors or air filters. The CTS technique presents an easy-accessible and highly efficient approach for synthesizing CNTs, which may be also applied in synthesizing other nanomaterials.

Natural materials are often compositionally and structurally heterogeneous for realizing particular functions. Inspired by nature, researchers have designed hybrid materials that possess properties beyond each of the components. Particularly, it remains a great challenge to realize site‐specific anisotropy, which widely exists in natural materials and is responsible for unique mechanical properties as well as physiological behaviors. Herein, the spontaneous formation of aligned graphene oxide (GO) flakes in sodium alginate (SA) matrix with locally controlled orientation via a direct‐ink‐writing printing process is reported. The GO flakes are spontaneously aligned in the SA matrix by shear force when being extruded and then arranged horizontally after drying on the substrate, forming a brick‐and‐mortar structure that could anisotropically contract or expand upon activation by heat, light, or water. By designing the printing pathways directed by finite element analysis, the orientation of GO flakes in the composite is locally controlled, which could further guide the composite to transform into versatile architectures. Particularly, the transformation is reversible when water vapor is applied as one of the stimuli. As a proof of concept, complex morphing architectures are experimentally demonstrated, which are in good consistency with the simulation results. A multistimuli‐responsive composite with locally controlled texture that can be printed into programmable shape‐morphing architectures is presented. The printed structures show fast, reversible, and multistimuli‐responsive shape‐morphing toward heat, light, and water (liquid and vapor).

Influenza hemagglutinin (HA) is the primary target of the humoral response during infection/vaccination. Current influenza vaccines typically fail to elicit/boost broadly neutralizing antibodies (bnAbs), thereby limiting their efficacy. Although several bnAbs bind to the conserved stem domain of HA, focusing the immune response to this conserved stem in the presence of the immunodominant, variable head domain of HA is challenging. We report the design of a thermotolerant, disulfide-free, and trimeric HA stem-fragment immunogen which mimics the native, prefusion conformation of HA and binds conformation specific bnAbs with high affinity. The immunogen elicited bnAbs that neutralized highly divergent group 1 (H1 and H5 subtypes) and 2 (H3 subtype) influenza virus strains in vitro. Stem immunogens designed from unmatched, highly drifted influenza strains conferred robust protection against a lethal heterologous A/Puerto Rico/8/34 virus challenge in vivo. Soluble, bacterial expression of such designed immunogens allows for rapid scale-up during pandemic outbreaks.

A novel electrocatalytic membrane reactor (ECMR), assembled by MnO x /Ti (MT) composite membrane as an anode, was used to degrade phenolic wastewater. The MT composite membrane, MnO x layer with the various crystal forms coated on porous tubular Ti support, was prepared by sol–gel method and then activated further by acidification to obtain acidified MnO x /Ti (AMT) composite membrane. The XRD results showed that the crystallite size of MnO x layer distinctly decreased after acidification. This is because of the Ti support had a great effect on the crystal form and crystallite size of MnO x , especially after acidification. The results of XPS analysis showed that the interaction between Ti support and MnO x layer had great influence on the Mn–O, Ti–O binding energies and active oxygen species of MT and AMT. Treated by ECMR with AMT, the phenol, COD and TOC removal rates of the synthetic phenolic wastewater were 96.45%, 84.97% and 71.26%, which were obviously higher than that of MT, 62.87%, 50.34% and 41.25%, respectively. It was revealed that acidified MnO x as the catalysts in AMT composite membrane, with the specific crystal form, refined crystallite size and active oxygen species, exhibited a great potential in the electrocatalytic oxidative degradation of the phenolic wastewater.

Escherichia coli O157:H7, Staphylococcus aureus, and Salmonella are major foodborne pathogens that are widespread in nature and responsible for several outbreaks of food safety accidents. Thus, a rapid and practical technique (PMA-mPCR) was developed for the simultaneous detection of viable E. coli O157:H7, S. aureus, and Salmonella in pure culture and in a food matrix. To eliminate false positive results, propidium monoazide (PMA) was applied to selectively suppress the DNA amplification of dead cells. The results showed the optimum concentration of PMA is 5.0 µg/mL. The detection limit of this assay by mPCR was 103 CFU/mL in the culture broth, and by PMA-mPCR was 104 CFU/mL both in pure culture and a food matrix (milk and ground beef). In addition, the detection of mixed viable and dead cells was also explored in this study. The detection sensitivity ratio of viable and dead counts was less than 1:10. Therefore, the PMA-mPCR assay proposed here might provide an efficient detection tool for the simultaneous detection of viable E. coli O157:H7, S. aureus, and Salmonella and also have great potential for the detection and concentration assessment of VBNC cells.

The crystal structure of Drosophila melanogaster YL1 in complex with an H2A.Z–H2B dimer exposes a selective recognition mechanism distinct from those of other H2A.Z chaperones and suggests a hierarchical transfer mechanism mediating H2A.Z deposition. Histone variant H2A.Z, a universal mark of dynamic nucleosomes flanking gene promoters and enhancers, is incorporated into chromatin by SRCAP (SWR1), an ATP-dependent, multicomponent chromatin-remodeling complex. The YL1 (Swc2) subunit of SRCAP (SWR1) plays an essential role in H2A.Z recognition, but how it achieves this has been unclear. Here, we report the crystal structure of the H2A.Z-binding domain of Drosophila melanogaster YL1 (dYL1-Z) in complex with an H2A.Z–H2B dimer at 1.9-Å resolution. The dYL1-Z domain adopts a new whip-like structure that wraps over H2A.Z–H2B, and preferential recognition is largely conferred by three residues in loop 2, the hyperacidic patch and the extended αC helix of H2A.Z. Importantly, this domain is essential for deposition of budding yeast H2A.Z in vivo and SRCAP (SWR1)-catalyzed histone H2A.Z replacement in vitro . Our studies distinguish YL1-Z from known H2A.Z chaperones and suggest a hierarchical mechanism based on increasing binding affinity facilitating H2A.Z transfer from SRCAP (SWR1) to the nucleosome.

H2A.Z is a highly conserved histone variant in all species. The chromatin deposition of H2A.Z is specifically catalyzed by the yeast chromatin remodeling complex SWR1 and its mammalian counterpart SRCAP. However, the mechanism by which H2A.Z is preferentially recognized by non-histone proteins remains elusive. Here we identified Anp32e, a novel higher eukaryote-specific histone chaperone for H2A.Z. Anp32e preferentially associates with H2A.Z-H2B dimers rather than H2A-H2B dimers in vitro and in vivo and dissociates non-nucleosomal aggregates formed by DNA and H2A-H2B. We determined the crystal structure of the Anp32e chaperone domain (186-232) in complex with the H2A.Z-H2B dimer. In this structure, the region containing Anp32e residues 214-224, which is absent in other Anp32 family proteins, specifically interacts with the extended H2A.Z αC helix, which exhibits an unexpected conformational change. Genome-wide profiling of Anp32e revealed a remarkable co-occupancy between Anp32e and H2A.Z. Cells overexpressing Anp32e displayed a strong global H2A.Z loss at the +1 nucleosomes, whereas cells depleted of Anp32e displayed a moderate global H2A.Z increase at the +1 nucleosomes. This suggests that Anp32e may help to resolve the non-nucleosomal H2A.Z aggregates and also facilitate the removal of H2A.Z at the +1 nucleosomes, and the latter may help RNA polymerase II to pass the first nucleosomal barrier.