The drive toward more sustainable agriculture has raised the profile of crop plant nutrient-use efficiency. Here we show that a major rice nitrogen-use efficiency quantitative trait locus (qNGR9) is synonymous with the previously identified gene DEP1 (DENSE AND ERECT PANICLES 1). The different DEP1 alleles confer different nitrogen responses, and genetic diversity analysis suggests that DEP1 has been subjected to artificial selection during Oryza sativa spp. japonica rice domestication. The plants carrying the dominant dep1-1 allele exhibit nitrogen-insensitive vegetative growth coupled with increased nitrogen uptake and assimilation, resulting in improved harvest index and grain yield at moderate levels of nitrogen fertilization. The DEP1 protein interacts in vivo with both the Gα (RGA1) and Gβ (RGB1) subunits, and reduced RGA1 or enhanced RGB1 activity inhibits nitrogen responses. We conclude that the plant G protein complex regulates nitrogen signaling and modulation of heterotrimeric G protein activity provides a strategy for environmentally sustainable increases in rice grain yield.
Halide double perovskites have recently bloomed as the green candidates for optoelectronic applications, such as X‐ray detection. Despite great efforts, the exploration of promising organic–inorganic hybrid double perovskites toward X‐ray detection remains unsuccessful. Now, single crystals of the lead‐free hybrid double perovskite, (BA)2CsAgBiBr7 (BA+ is n‐butylammonium), featuring the unique 2D multilayered quantum‐confined motif, enable quite large μτ (mobility‐lifetime) product up to 1.21×10−3 cm2 V−1. This figure‐of‐merit realized in 2D hybrid double perovskites is unprecedented and comparable with that of CH3NH3PbI3 wafers. (BA)2CsAgBiBr7 crystals also exhibit other intriguing attributes for X‐ray detection, including high bulk resistivity, low density of defects and traps, and large X‐ray attenuation coefficient. Consequently, a vertical‐structure crystal device under X‐ray source yields a superior sensitivity of 4.2 μC Gyair−1 cm−2.
Cryptococcus neoformans (Cn), the major causative agent of human fungal meningoencephalitis, replicates within phagolysosomes of infected host cells. Despite more than a half-century of investigation into host-Cn interactions, host factors that mediate infection by this fungal pathogen remain obscure. Here, we describe the development of a system that employs Drosophila S2 cells and RNA interference (RNAi) to define and characterize Cn host factors. The system recapitulated salient aspects of fungal interactions with mammalian cells, including phagocytosis, intracellular trafficking, replication, cell-to-cell spread and escape of the pathogen from host cells. Fifty-seven evolutionarily conserved host factors were identified using this system, including 29 factors that had not been previously implicated in mediating fungal pathogenesis. Subsequent analysis indicated that Cn exploits host actin cytoskeletal elements, cell surface signaling molecules, and vesicle-mediated transport proteins to establish a replicative niche. Several host molecules known to be associated with autophagy (Atg), including Atg2, Atg5, Atg9 and Pi3K59F (a class III PI3-kinase) were also uncovered in our screen. Small interfering RNA (siRNA) mediated depletion of these autophagy proteins in murine RAW264.7 macrophages demonstrated their requirement during Cn infection, thereby validating findings obtained using the Drosophila S2 cell system. Immunofluorescence confocal microscopy analyses demonstrated that Atg5, LC3, Atg9a were recruited to the vicinity of Cn containing vacuoles (CnCvs) in the early stages of Cn infection. Pharmacological inhibition of autophagy and/or PI3-kinase activity further demonstrated a requirement for autophagy associated host proteins in supporting infection of mammalian cells by Cn. Finally, systematic trafficking studies indicated that CnCVs associated with Atg proteins, including Atg5, Atg9a and LC3, during trafficking to a terminal intracellular compartment that was decorated with the lysosomal markers LAMP-1 and cathepsin D. Our findings validate the utility of the Drosophila S2 cell system as a functional genomic platform for identifying and characterizing host factors that mediate fungal intracellular replication. Our results also support a model in which host Atg proteins mediate Cn intracellular trafficking and replication.
Antiferroelectrics, characterized by the natural polarization-electric field (P−E) double hysteresis loops, has been developed as a promising branch for energy storage. Here, we present the first antiferroelectric in the booming family of lead iodide hybrid perovskites, (BA) 2 (EA) 2 Pb 3 I 10 (1, where BA = n-butylammonium and EA = ethylammonium), which exhibits one of the highest Curie temperatures (∼363 K) for the majority of known molecular systems. Strikingly, its high-temperature antiferroelectricity, triggered by an antipolar alignment of adjacent dipoles, is confirmed by the characteristic double P−E hysteresis loops, thus enabling remarkable energy storage efficiencies in the range of 65%−83%. This merit is almost comparable to those of many inorganic counterparts, suggesting the great potential of 1 for energy storage. Another fascinating attribute is that 1 also acts as a room-temperature biaxial ferroelectric with spontaneous polarization of 5.6 μC•cm −2 . As far as we know, this study on the high-temperature antiferroelectric, along with room-temperature biaxial ferroelectricity, is unprecedented for the versatile lead iodide hybrid perovskites, which sheds light on the design of new electric-ordered materials and facilitates their application of high-performance devices.
Two-dimensional (2D) hybrid perovskites of Ruddlesden−Popper (RP) lattices are recently booming as a vigorous class of ferroelectrics, whereas their intrinsic van der Waals gaps exert weak interactions that destabilize the layered motifs. Thus, it is an urgent challenge to reduce interlayered energy gaps to allow an exploration of stable RP ferroelectrics. Here, we propose hydrogen bonds to reduce van der Waals gaps of 2D RP-type perovskites while the ferroelectricity is retained. For the first time, a homoconformational trans isomer has been alloyed as the spacing cation of the 2D ferroelectric (t-ACH) 2 (EA) 2 Pb 3 Br 10 (1, where t-ACH is 4-aminomethyl-1-cyclohexanecarboxylate and EA is ethylammonium). Strikingly, the strong O−H•••O hydrogen bonds link adjacent spacing sheets to build a quasi-RP motif with a lower energy gap. In terms of ferroelectricity, the mixed-cation alloying has a crucial role in spontaneous polarization (P s ), as verified by structure analyses, quadratic optical nonlinearity, and electric hysteresis loops. The ordering of t-ACH + and EA + cations induces mmmFm symmetry breaking, along with an unusual in-plane P s value of ∼2.9 μC/cm 2 in the ac plane. In combination with the anisotropic nature of its 2D motif, this ferroelectricity creates strong linearly polarized light sensitivity with a large dichroism ratio of ∼3.2, far beyond those of most of the inorganic 2D systems. As far as we know, a 2D RPtype ferroelectric with a trans isomer cationic spacer is unprecedented, and the concept of reducing energy gaps via H-bonding interactions will strengthen the layered perovskite structure and shed light on the rational design of stable ferroelectrics toward photoelectric applications.
Polarization-sensitive ultraviolet (UV) photodetection is highly indispensable in military and civilian applications and has been demonstrated with various wide-band photodetectors. However, it still remains elusive to achieve the selfpowered devices, which can be operated in the absence of external bias. Herein, for the first time, ferroelectricity-driven self-powered photodetection towards polarized UV light was successfully demonstrated in a 2D wide-band gap hybrid ferroelectric (BPA) 2 PbBr 4 (BPA = 3-bromopropylammonium) (1). We found that the prominent spontaneous polarization in 1 results in a bulk photovoltaic effect (BPVE) of 0.85 V, that independently drives photoexcited carriers separation and transport and thus supports self-powered ability. This self-powered detector shows strong polarization sensitivity to linearly polarized UV illumination with a polarization ratio up to 6.8, which is superior to that of previously reported UVpolarized photodetectors (ZnO, GaN, and GeS 2). Polarization-sensitive photodetectors have attracted extensive attention owing to their remarkable polarization dependent optoelectronic properties. [1-3] Among them, polarizationsensitive ultraviolet (UV) photodetection capable of detecting polarized UV light is a significant branch of optoelectronics and has been adapted to various fields, ranging from communication, near field imaging, remote sensing, as well as to military surveillance. [4-9] During the past decades, most attention on polarization-sensitive UV photodetection was devoted to conventional wide band gap semiconductor medium with nanowire geometry, such as GaN [4] and ZnO. [5] Recently, anisotropic 2D semiconductor GeS 2 also has been demonstrated to be potential building element for UVpolarized detection due to the intrinsic anisotropic crystal structure. [10] However, an external power source was usually required as driving force in all above mentioned devices to separate the photogenerated carriers, which not only consumed energy but also largely increased the system size and integrated cost. Self-powered photodetectors represent a new type of candidate without external energy supply, which can
Single crystals of lead halide hybrid perovskites (e. g., CH3NH3PbI3 and CsPbBr3) have been developed as promising candidates for X-ray detection, owing to their excellent attributes including low trap density, high X-ray absorption cross section, and high carrier mobility. The toxicity of lead, however, is a potential bottleneck that hinders their device application toward green and sustainable competitors. Herein, we reported a new lead-free bismuth-iodide hybrid of (H2MDAP)BiI5 (1, H2MDAP = N-methyl-1,3-diaminopropanium), adopting one-dimensional (1D) metal-halogen frameworks, which behaves as a potential alternative for X-ray detection. Large-size single crystals of 1 with sizes up to 9 × 7 × 4 mm3 were successfully grown via top-seeded solution growth method. The as-grown crystal exhibits notable semiconducting properties, including a narrow bandgap of 1.83 eV, trap density of 3.6 × 1011 cm–3, carrier mobility of 1.42 cm2 V–1 s–1, and high X-ray absorption coefficient. Consequently, the fabricated crystal-based X-ray photoconductor enables the conversion of X-ray to electrical signals with a sensitivity of ∼1.0 μC Gyair –1 cm–2. These results throw light on further exploration on X-ray-sensitive materials based on the lead-free metal halogen hybrids.
Figure 4. a) Schematic structure for the polarized-light detector of 1. The irradiating area of single crystal (top left) is 4 × 10 −4 cm 2 . b) I-V curves of 1 measured under different intensities of polarized illumination (λ = 405 nm). c) Long-time switching cycles of photo-responses for 1. d) Temporal measurements of photocurrents, affording the t r /t f values of ≈200/300 µs, respectively. 1907020 (6 of 6) www.advancedsciencenews.com
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