To distinctively identify two objects at the deep-subwavelength scales requires sharp superfocusing to overcome the diffraction limit. However, conventional superfocusing effect and information-carrying capacity are limited by the focal length and single focusing field (only electric or magnetic field), which are hard to be apparently improved. Here, we introduce the concept of “dual-foci superfocusing”, an advanced focusing form that can provide either one or two focusing spots, simultaneously converging both electric and magnetic fields and presenting an effect of electromagnetostatic space-division multiplexing. The physical mechanism of the dual-foci superfocusing is analyzed and synthesized by an original theory of shaping functional fields using hybrid-magnitude evanescent modes. Through a terahertz plasmonic array, the dual-foci superfocusing is numerically demonstrated, whose metric (ratio of focal length to focusing-spot size) is sufficiently improved from traditional 1–1.8 up to 2.8. The proposed methodology could be exploited as a platform to investigate the novel concurrent characteristics of superfocusing and might represent an important step toward the development of beam manipulation and sophisticated holography.
Microfluidic droplets are widely applied in various fields such as biomedicine, aerospace, energy utilization, and chemical engineering due to their advantages of large specific surface area, uniform size, stability, and easy control. The double T-shaped microchannel has the characteristics of rapid preparation of microdroplets with controllable size and good uniformity. Through 3D numerical simulation, the influence of the constriction structure of the microchannel on the formation of droplets was studied qualitatively and quantitatively. Compared with ordinary double T-shaped microchannels, the microchannels with a necked structure generate smaller droplets in diameter and faster generation frequency. Among the three structures of rectangular necking, inverted trapezoidal necking, and trapezoidal necking, the microchannel with the latter structure has the best performance, can produce monodisperse droplets of uniform size, and the period is stable.
Genetic variability has significant impacts on biological characteristics and pathogenicity of hepatitis B virus (HBV), in which the N-terminal sequence of the presurface 1 (preS1) region of HBV large surface protein (LHBs) displays genotype (GT) dependent genetic heterogeneity. However, the influence of this heterogeneity on its biological roles is largely unknown. By analyzing 6560 full-length genome sequences of GTA-GTH downloaded from HBVdb database, the preS1 N-terminal sequences were divided into four representative types, namely C-type (representative of GTA, GTB, and GTC), H-type (GTF and GTH), E-type (GTE and GTG), and D-type (GTD), respectively. We artificially substituted the preS1 N-termini of GTC and GTD plasmids or viral strains with each sequence of the four representative types. The roles of preS1 N-terminus on HBV replication, secretion and infectivity were investigated using HepG2 or HepG2-NTCP cells. In the transfection experiments, the results showed that the extracellular HBsAg levels and HBsAg secretion coefficients in D- and E-type strains were significantly higher than those in C- and H-type strains. D-type strain produced more extracellular HBV DNA than C-type strain. We further observed that D-, H-, and E-type strains increased the levels of intracellular replicative HBV DNAs, comparing with C-type strain. In the infection experiments, the levels of extracellular HBeAg, intracellular HBV total RNA and pgRNA/preC mRNA in D- and E-type strains were markedly higher than C and H-type ones. Our data suggest that the preS1 N-termini affect HBV replication, secretion and infectivity in a genotype dependent manner. The C- and H-type strains prefer to attenuate HBsAg secretion, while the strains of D- and E-type promoted infectivity. The existence and function of the intergenotypic shift of preS1 in naturally occurring recombination requires further investigation, as the data we acquired are mostly related to recombinant preS1 region between N-terminus of preS1 from genotypes A-H and the remaining preS1 portion of GTC or GTD.
Keywords: HBV large surface protein; genotype; hepatitis B virus; heterogeneity; preS1 N-terminus.
Water competition between the food and energy sector is a critical component of the food-energy-water nexus. However, few studies have systematically characterized the geospatial and, especially, the sub-annual variations in such competition and the associated environmental impacts and targeted mitigation opportunities. This study characterizes competing water uses for crop-specific irrigated agriculture and fuel-specific power generation across global major river basins to reveal their resulting impacts on local water scarcity for global population under both current and a warming climate. Under annual (and most seasonal) accounting, almost all basins currently suffering from extremely high water scarcity are dominated by agricultural water consumption (e.g. accommodating 26%–49% of basin-total population across seasons), which are often simultaneously exposed to potentially decreasing seasonal water availability under a 4 °C warming scenario. Only 13%–20% of population are located in basins dominated by seasonal power sector water uses, which are predominantly with low water scarcity. Agriculture sector provides the most basin-specific water mitigation opportunities across mid-latitude basins in all four seasons. Nevertheless, power sector becomes more important in affecting seasonal water scarcity and provides unique seasonal water mitigation opportunities, particularly in basins among higher northern latitudes in winter. This analysis highlights irrigated agriculture is currently and will likely remain the key in global water management for basins facing the severest water scarcity, yet increasing attention on the seasonal and spatial variations in cross-sector water use competition is needed to better identify region- and season- specific mitigation opportunities.
Abstract Angiosperm sexual systems are fundamental to the evolution and distribution of plant diversity, yet spatiotemporal patterns in angiosperm sexual systems and their drivers remain poorly known. Using data on sexual systems and distributions of 68453 angiosperm species, we present the first global maps of sexual system frequencies and evaluate sexual system evolution during the Cenozoic. Frequencies of dioecy and monoecy increase with latitude, while hermaphrodites are more frequent in warm and arid regions. Transitions to dioecy from other states were higher than to hermaphroditism, but transitions away from dioecy increased since the Cenozoic, suggesting that dioecy is not an evolutionary end point. Transitions between hermaphroditism and dioecy increased, while transitions to monoecy decreased with paleo-temperature when paleo-temperature >℃. Our study demonstrates the biogeography of angiosperm sexual systems from a macroecological perspective, and enhances our understanding of plant diversity patterns and their response to climate change.