Sparking potential over 1200 V by a falling water droplet.

Hydrovoltaic technology has achieved notable breakthroughs in electric output via using the moving boundary of electric double layer, but the output voltage induced by droplets is saturated around 350 volts, and the underlying mechanism remains to be further clarified. Here, we show that falling water droplets can stably spark an unprecedented voltage up to 1200 volts within microseconds that they contact an electrode placed on top of an electret surface, approaching the theoretical upper limit. This sparking potential can be explained and described by a comprehensive model considering the water-electrode contact dynamics from both the macroscale droplet spreading and the microscale electric double layer formation, as well as the presence of a circuit capacitance. It is demonstrated that a droplet-induced electric spark is sufficient to directly ionize gas at atmospheric pressure and split water into hydrogen and oxygen, showing wide application potential in fields of green energy and intelligence.

Periodic fracture behaviour of nanomembranes.

Fracture control in membranes is highly desirable in nano-technology, but is a great challenge because of the 'multi-scale' complexity of fracture initiation and propagation. Here, we devise a method that can controllably direct fractures in stiff nanomembranes, realized by 90° peeling of the nanomembrane overlaid on a soft film, i.e., a stiff/soft bilayer, from a substrate underneath. The peeling allows the stiff membrane to be creased into a soft film periodically in the bending region and fractured along the unique bottom line of the crease, i.e, the fracture route is strictly straight and periodic. The facture period is tunable, because the surface perimeter of the creases is determined by the thickness and modulus of the stiff membranes. This is a new kind of fracture behavior of stiff membranes, which is unique to stiff/soft bilayers but universally exists in such systems, promising a new generation of technology for cutting nanomembranes.

Chromosome-Level Genome Assembly of Papilio elwesi Leech, 1889 (Lepidoptera: Papilionidae).

A rarely seen butterfly species, the large swallowtail butterfly Papilio elwesi Leech, 1889 (Lepidoptera: Papilionidae), endemic to the Chinese mainland, has been declared a state-protected animal in China since 2000, but its genome is not yet available. To obtain high-quality genome assembly and annotation, we sequenced the genome and transcriptome of P. elwesi using the PacBio and PromethION platforms, respectively. The final assembled genome was 358.51 Mb, of which 97.59% was anchored to chromosomes (30 autosomes and 1 Z sex chromosome), with a contig/scaffold N50 length of 6.79/12.32 Mb and 99.0% (n = 1367) BUSCO completeness. The genome annotation pointed to 36.82% (131.99 Mb) repetitive elements and 1296 non-coding RNAs in the genome, along with 13,681 protein-coding genes that cover 98.6% (1348) of the BUSCO genes. Among the 11,499 identified gene families, 104 underwent significantly rapid expansions or contractions, and these rapidly expanding families play roles in detoxification and metabolism. Additionally, strong synteny exists between the chromosomes of P. elwesi and P. machaon. The chromosome-level genome of P. elwesi could serve as an important genomic resource for furthering our understanding of butterfly evolution and for more in-depth genomic analyses.

3D Single-Layer-Dominated Graphene Foam for High-Resolution Strain Sensing and Self-Monitoring Shape Memory Composite.

Flexible intelligent materials are desired to effectively regulate their own deformation and accurately sense their immediate morphology at the same time. Graphene foam is an attractive material for strain sensing and electrical/thermal performance control due to its outstanding mechanical, electrical, and thermal properties. However, graphene-foam-based materials with both strain sensing and deformation control capabilities are rarely reported. Here, a multiscale design of graphene foam with a single-layer-graphene-dominated microstructure and resilient 3D network architecture, which leads to exceptional strain sensing performance as well as modulation ability of the electrical and thermal conductivity for shape memory polymers, is reported. The graphene foams exhibit a strain detection limit of 0.033%, a rapid response of 53 ms, long-term stability over 10 000 cycles, significant thermoacoustic effect, and great heat-generation and heat-diffusion ability. By combining these advantages, an electro-activated shape-memory composite that is capable of monitoring its own shape state during its morphing process, is demonstrated.

Self-sustained electricity generator driven by the compatible integration of ambient moisture adsorption and evaporation.

Generating sustainable electricity from ambient humidity and natural evaporation has attracted tremendous interest recently as it requires no extra mechanical energy input and is deployable across all weather and geography conditions. Here, we present a device prototype for enhanced power generation from ambient humidity. This prototype uses both heterogenous materials assembled from a LiCl-loaded cellulon paper to facilitate moisture adsorption and a carbon-black-loaded cellulon paper to promote water evaporation. Exposing such a centimeter-sized device to ambient humidity can produce voltages of around 0.78 V and a current of around 7.5 µA, both of which can be sustained for more than 10 days. The enhanced electric output and durability are due to the continuous water flow that is directed by evaporation through numerous, negatively charged channels within the cellulon papers. The voltage and current exhibit an excellent scaling behavior upon device integration to sufficiently power commercial devices including even cell phones. The results open a promising prospect of sustainable electricity generation based on a synergy between spontaneous moisture adsorption and water evaporation.

One-pot aqueous synthesis of sub-10 nm responsive nanogels.

A strategy involving free radical copolymerization of a difunctional oligomer and a small-molecule crosslinker to give sub-10 nm nanogels is proposed. These nanogels can adapt to surrounding temperatures and regulate the release of a preloaded model anticancer drug 5-fluorouracil.