Insights into the phylogenetic relationships and species boundaries of the Myricaria squamosa complex (Tamaricaceae) based on the complete chloroplast genome.

Myricaria plants are widely distributed in Eurasia and are helpful for windbreak and embankment protection. Current molecular evidence has led to controversy regarding species boundaries within the Myricaria genus and interspecific phylogenetic relationships between three specific species-M. bracteata, M. paniculata and M. squamosa-which have remained unresolved. This study treated these three unresolved taxa as a species complex, named the M. squamosa complex. The genome skimming approach was used to determine 35 complete plastome sequences and nuclear ribosomal DNA sequences for the said complex and other closely related species, followed by de novo assembly. Comparative analyses were conducted across Myricaria to identify the genome size, gene content, repeat type and number, SSR (simple sequence repeat) abundance, and codon usage bias of chloroplast genomes. Tree-based species delimitation results indicated that M. bracteata, M. paniculata and M. squamosa could not be distinguished and formed two monophyletic lineages (P1 and P2) that were clustered together. Compared to plastome-based species delimitation, the standard nuclear DNA barcode had the lowest species resolution, and the standard chloroplast DNA barcode and group-specific barcodes delimitated a maximum of four out of the five species. Plastid phylogenomics analyses indicated that the monophyletic M. squamosa complex is comprised of two evolutionarily significant units: one in the western Tarim Basin and the other in the eastern Qinghai-Tibet Plateau. This finding contradicts previous species discrimination and promotes the urgent need for taxonomic revision of the threatened genus Myricaria. Dense sampling and plastid genomes will be essential in this effort. The super-barcodes and specific barcode candidates outlined in this study will aid in further studies of evolutionary history.

Fabrication of 3D macroporous Fe3O4-GO-Ni through a 'nano-reinforced concrete' method in the application of flexible supercapacitors.

Aqueous flexible supercapacitors have promising potential in the application of wearable electronics but are limited by their low energy densities. Typically, thin nanostructured active materials are deposited on current collectors to achieve high specific capacitances based on active materials, yet the capacitance of total electrodes is sacrificed. The fabrication of 3D macroporous current collectors is a pioneering solution to retain the high specific capacitances of both active materials and electrodes, achieving supercapacitors with high energy density. In this work, through a 'nano-reinforced concrete' method, Fe3O4-GO-Ni with a 3D macroporous structure is synthesized on the surface of cotton threads. In the synthesis process, Ni, hollow Fe3O4 microspheres and graphene oxide (GO) function as the adhesive, fillers, and reinforced and structural materials, respectively. The resultant Fe3O4-GO-Ni@cotton exhibits ultrahigh specific capacitances of 4.71 and 1.85 F cm-2 as positive and negative electrodes, respectively. The electrodes with 3D macroporous structures have good compatibility with the volume change of active materials during the charge-discharge process, leading to excellent long-cycle performance up to 10 000 charge-discharge cycles. To demonstrate the potential of practical applications, a flexible symmetric supercapacitor is fabricated using Fe3O4-GO-Ni@cotton electrodes and shows an energy density of 19.64 mW h cm-3.

Flood impacts on urban road connectivity in southern China.

Effective measures to improve road accessibility during storms are required as traffic congestion caused by storm floods increasingly constrains the efficiency of urban commuting. However, flood impacts on urban road connectivity are not yet well assessed due to inaccurate simulation of flood processes in urban areas where high-resolution data for drainage networks and gauged hydrological data are insufficient. Thus, this study assesses flood impacts on road network connectivity in an urban area of southern China through joint modeling of 1-D hydrodynamic processes in drainage networks and 2-D flood inundation processes on roads using MIKE Urban and MIKE 21. High-resolution DEM images of 5 m and a drainage network of 5635 pipelines were used for urban hydrological simulation. Flood depths were gauged for model calibration and validation by recruited volunteers in the context of citizen science. The results show that road network connectivity decreases as rainfall increases. More than 40% of road connectivity is lost in the study area when a 1-in-100-year return period rainfall occurs. The study results can help to inform more adaptive strategies for local flood control. The study methods are also applicable to improving urban hydrological modeling in broader regions.

In situ synthesis and immobilization of metallic nanoparticles on a calixarene monolayer.

A covalently immobilized calix[7]hydroquinone monolayer was used as the host matrix to synthesize metallic NPs using an in situ redox process. The characteristics of different metallic ions that affect the synthesis process were studied. Metallic ions with less charges, lower oxidation state in the reaction, and higher standard redox potential provided better yield. Bimetallic NPs with a core-shell structure were synthesized by a sequential deposition of different metals on the same monolayer. The process was applied to form a layer of immobilized NPs on flat and curved surfaces. The ability to synthesize and immobilize well-controlled NPs on different surfaces has promising applications in decoration of irregular surfaces of miniaturized, three-dimensional objects.

Covalent molecular assembly: construction of ultrathin multilayer films by a two-dimensional fabrication method.

A two-dimensional fabrication method was employed to assemble ultrathin multilayer films with specific three-dimensional structures by making use of interlayer and intralayer covalent bonding. The films were assembled in a layer-wise fashion on a silicon surface using bi- and multi-functional molecules as building blocks and strengthened by lateral cross-linking. The fabrication process could be controlled at the sub-nano-scale with the roughness of the surface after deposition of each layer within 0.2 nm. The film showed better resistance to harsh environments than randomly cross-linked or linearly linked films of comparable thickness. The combination of covalent LbL assembly and lateral cross-linking has significant potential as a method of fabrication for assembling nano-structures for a variety of applications.