As the most promising lead‐free one, tin‐halides based perovskite solar cells still suffer from the severe bulk‐defect due to the easy oxidation of tin from divalent to tetravalent. Here, a general ...and effective strategy is delivered to modulate the microstructure of 2D/3D heterogeneous tin‐perovskite absorber films by substituting FAI with FPEABr in FASnI3. The introduction of 2D phase can induce highly oriented growth of 3D FASnI3 and it is revealed in the optimal 2D/3D film that 2D phase embraces 3D grains and locates at the surfaces and grain boundaries. The FPEA+ based 2D tin‐perovskite capping layer can offer a reducing atmosphere for vulnerable 3D FASnI3 grains. The unique microstructure effectively suppresses the well‐known oxidation from Sn2+ to Sn4+, as well as decreasing defect density, which leads to a remarkable enhanced device performance from 9.38% to 14.81% in conversion efficiency. The certified conversion efficiency of 14.03% announces a new record and moves a remarkable step from the last one (12.4%). Besides of this breakthrough, this work definitely paves a new way to fabricate high‐quality tin‐perovskite absorber film by constructing effective 2D/3D microstructures.
A general and effective strategy is delivered to modulate the 2D/3D microstructure of tin‐perovskite films by introduction of a 2D phase with the function of FPEABr, which induces high‐orientation growth of 3D FASnI3 by embracing the 3D grains at their surfaces and boundaries. That leads to a breakthrough of device performance of 14.81% in power conversion efficiency, along with 14.03% certified.
As the most promising lead‐free branch, tin halide perovskites suffer from the severe oxidation from Sn2+ to Sn4+, which results in the unsatisfactory conversion efficiency far from what they ...deserve. In this work, by facile incorporation of methylammonium bromide in composition engineering, formamidinium and methylammonium mixed cations tin halide perovskite films with ultrahighly oriented crystallization are synthesized with the preferential facet of (001), and that oxidation is suppressed with obviously declined trap density. MA+ ions are responsible for that impressive orientation while Br‐ ions account for their bandgap modulation. Depending on high quality of the optimal MA0.25FA0.75SnI2.75Br0.25 perovskite films, their device conversion efficiency surges to 9.31% in contrast to 5.02% of the control formamidinium tin triiodide perovskite (FASnI3) device, along with almost eliminated hysteresis. That also results in the outstanding device stability, maintaining above 80% of the initial efficiency after 300 h of light soaking while the control FASnI3 device fails within 120 h. This paper definitely paves a facile and effective way to develop high‐efficiency tin halide perovskites solar cells, optoelectronic devices, and beyond.
MABr induces the remarkably oriented growth of tin halide perovskite films (MAxFA1−xSnI3−xBrx) by alloying, which results in an optimal device conversion efficiency of 9.31% enhanced from 5.02% of the pristine FASnI3 device and maintained above 80% of the initial efficiency after 300 h light soaking while the control device fails within 120 h.
The repeating fast radio burst (FRB) source that produced FRB 121102 was recently localized in a star-forming galaxy at z = 0.193, which is associated with an extended radio source at the burst ...location. One possibility is that the repeating FRBs are produced by a new-born magnetar, which also powers the radio nebula. If so, the magnetar may produce γ-ray emission due to magnetic dipolar spin-down. The luminosity depends on the magnetar spin parameters and age. We process the eight-year Fermi-LAT data at the position of FRB 121102 and place an energy flux upper limit of in time bins with six-month intervals, and an accumulated energy flux upper limit of over the eight-year span. The corresponding γ-ray luminosity upper limits are and for the time-resolved and time-integrated analyses, respectively. We discuss the implications of these limits on the young magnetar model.
Abstract
Short-duration gamma-ray bursts (sGRBs) are commonly attributed to the mergers of double neutron stars (NSs) or the mergers of a neutron star with a black hole (BH). While the former ...scenario was confirmed by the event GW170817, the latter remains elusive. Here, we consider the latter scenario in which an NS is tidally disrupted by a fast-spinning low-mass BH and the accretion onto the BH launches a relativistic jet and hence produces an sGRB. The merging binary’s orbit is likely misaligned with the BH’s spin. Hence, the Lense–Thirring precession around the BH may cause a hyperaccreting thick disk to precess in a solid-body manner. We propose that a jet, initially aligned with the BH spin, is deflected and collimated by the wind from the disk, therefore being forced to precess along with the disk. This would result in a quasiperiodic oscillation or modulation in the gamma-ray light curve of the sGRB, with a quasi-period of ∼0.01–0.1 s. The appearance of the modulation may be delayed respective to the triggering of the light curve. This feature, unique to the BH–NS merger, may have already revealed itself in a few observed sGRBs (such as GRB 130310A), and it carries the spin–orbit orientation information of the merging system. Identification of this feature would be a new approach to reveal spin–orbit misaligned merging BH–NS systems, which are likely missed by the current gravitational-wave searching strategy that is principally targeting aligned systems.
Abstract
The brightest gamma-ray burst, GRB 221009A, has spurred numerous theoretical investigations, with particular attention paid to the origins of ultrahigh-energy TeV photons during the prompt ...phase. However, analyzing the mechanism of radiation of photons in the ∼MeV range has been difficult because the high flux causes pileup and saturation effects in most GRB detectors. In this Letter, we present systematic modeling of the time-resolved spectra of the GRB using unsaturated data obtained from the Fermi Gamma-ray Burst Monitor (precursor) and SATech-01/GECAM-C (main emission and flare). Our approach incorporates the synchrotron radiation model, which assumes an expanding emission region with relativistic speed and a global magnetic field that decays with radius, and successfully fits such a model to the observational data. Our results indicate that the spectra of the burst are fully in accordance with a synchrotron origin from relativistic electrons accelerated at a large emission radius. The lack of thermal emission in the prompt emission spectra supports a Poynting flux–dominated jet composition.
Nitrogen is one of the most important nutrients needed for plants and algae to survive, and the photosynthetic ability of algae is related to nitrogen abundance. Red algae are unique photosynthetic ...eukaryotic organisms in the evolution of algae, as they contain phycobilisomes (PBSs) on their thylakoid membranes. In this report, the in vivo chlorophyll (Chl) a fluorescence kinetics of nitrogen-starved Porphyridium cruentum were analyzed to determine the effects of nitrogen deficiency on photosynthetic performance using a multi-color pulse amplitude modulation (PAM) chlorophyll fluorometer. Due to nitrogen starvation, the photochemical efficiency of PSII and the activity of PSII reaction centers (RCs) decreased, and photoinhibition of PSII occurred. The water-splitting system on the donor side of PSII was seriously impacted by nitrogen deficiency, leading to the inactivation of the oxygen-evolving complex (OEC) and decreased light energy conversion efficiency. In nitrogen-starved cells, a higher proportion of energy was used for photochemical reactions, and thermal dissipation was reduced, as shown by qP and qN. The ability of nitrogen-starved cells to tolerate and resist high photon flux densities was weakened. Our results showed that the photosynthetic performance of P. cruentum was severely impacted by nitrogen deficiency.
Background and Aims
NAFLD is considered as the hepatic manifestation of the metabolic syndrome, which includes insulin resistance, obesity and hyperlipidemia. NASH is a progressive stage of NAFLD ...with severe hepatic steatosis, hepatocyte death, inflammation, and fibrosis. Currently, no pharmacological interventions specifically tailored for NASH are approved. Ovarian tumor domain, ubiquitin aldehyde binding 1 (OTUB1), the founding member of deubiquitinases, regulates many metabolism‐associated signaling pathways. However, the role of OTUB1 in NASH is unclarified.
Methods and Results
We demonstrated that mice with Otub1 deficiency exhibited aggravated high‐fat diet–induced and high‐fat high‐cholesterol (HFHC) diet–induced hyperinsulinemia and liver steatosis. Notably, hepatocyte‐specific overexpression of Otub1 markedly alleviated HFHC diet–induced hepatic steatosis, inflammatory responses, and liver fibrosis. Mechanistically, we identified apoptosis signal–regulating kinase 1 (ASK1) as a key candidate target of OTUB1 through RNA‐sequencing analysis and immunoblot analysis. Through immunoprecipitation–mass spectrometry analysis, we further found that OTUB1 directly bound to tumor necrosis factor receptor–associated factor 6 (TRAF6) and suppressed its lysine 63–linked polyubiquitination, thus inhibiting the activation of ASK1 and its downstream pathway.
Conclusions
OTUB1 is a key suppressor of NASH that inhibits polyubiquitinations of TRAF6 and attenuated TRAF6‐mediated ASK1 activation. Targeting the OTUB1‐TRAF6‐ASK1 axis may be a promising therapeutic strategy for NASH.
Converting degraded croplands into perennials has been proposed as an effective method of soil N sequestration, however, the dynamics of deep soil N (>100 cm) following cropland conversion are not ...well understood. In this study, we synthesized 3049 observations to detect the changes in deep soil N content following cropland conversion on the arid and semiarid Loess Plateau. Our results showed that converting croplands into perennials significantly increased the soil N content by an average of 57.4%, 23.1%, and 29.5% in the surface (0–20 cm), subsurface (20–100 cm), and deep (100–200 cm) layers, respectively. The extent of the increase was influenced significantly by the land‐use conversion types and tree species. Specifically, the conversion of croplands into deep‐rooted forests or shrubs, particularly Robinia pseudoacacia and Caragana microphylla, exhibited higher advantages in deep soil N sequestration. Moreover, deep soil N sequestration increased significantly with time since cropland conversion (p < 0.001), and the rates in deep soils were approximately 26.1% and 66.7% of that in 0–20 and 20–100 cm soils, respectively. In the long term, converting croplands into forests and shrubs showed higher potential for deep soil N sequestration. Linear regression analysis showed that the changes of deep soil N sequestration were influenced significantly by initial soil N content (p < 0.001) and humidity index (p < 0.001), with the slopes in >100 cm layers being 2 to 3 times than that in the top meter, indicating higher sensitivity in deep soils. Overall, this study provides evidence that converting degraded croplands into perennials may contribute to deep soil N accumulation in N‐limited regions, which could potentially alleviate N limitation and sustain long‐term ecosystem carbon sequestration.
Genomic information has already been applied to prokaryotic species definition and classification. However, the contribution of the genome sequence to prokaryotic genus delimitation has been less ...studied. To gain insights into genus definition for the prokaryotes, we attempted to reveal the genus-level genomic differences in the current prokaryotic classification system and to delineate the boundary of a genus on the basis of genomic information. The average nucleotide sequence identity between two genomes can be used for prokaryotic species delineation, but it is not suitable for genus demarcation. We used the percentage of conserved proteins (POCP) between two strains to estimate their evolutionary and phenotypic distance. A comprehensive genomic survey indicated that the POCP can serve as a robust genomic index for establishing the genus boundary for prokaryotic groups. Basically, two species belonging to the same genus would share at least half of their proteins. In a specific lineage, the genus and family/order ranks showed slight or no overlap in terms of POCP values. A prokaryotic genus can be defined as a group of species with all pairwise POCP values higher than 50%. Integration of whole-genome data into the current taxonomy system can provide comprehensive information for prokaryotic genus definition and delimitation.
PDF
