A new kind of nitrogen‐doped graphene/carbon nanotube nanocomposite can be synthesized by a facile hydrothermal process under mild conditions, which exhibits synergistically enhanced electrochemical ...activity for the oxygen reduction reaction. This research provides a new route to access a metal‐free electrocatalyst with high activity under mild conditions.
Grain size is an important component trait of grain yield, which is frequently threatened by abiotic stress. However, little is known about how grain yield and abiotic stress tolerance are regulated. ...Here, we characterize GSA1, a quantitative trait locus (QTL) regulating grain size and abiotic stress tolerance associated with metabolic flux redirection. GSA1 encodes a UDP-glucosyltransferase, which exhibits glucosyltransferase activity toward flavonoids and monolignols. GSA1 regulates grain size by modulating cell proliferation and expansion, which are regulated by flavonoid-mediated auxin levels and related gene expression. GSA1 is required for the redirection of metabolic flux from lignin biosynthesis to flavonoid biosynthesis under abiotic stress and the accumulation of flavonoid glycosides, which protect rice against abiotic stress. GSA1 overexpression results in larger grains and enhanced abiotic stress tolerance. Our findings provide insights into the regulation of grain size and abiotic stress tolerance associated with metabolic flux redirection and a potential means to improve crops.
Nitrogen-doped graphene has been a recent research focus. It is crucial to further utilize the excellent properties of graphene macroscopic assemblies. Herein, we first report a unique and convenient ...hydrothermal process for controlled synthesis and structural adjustment of the nitrogen-doped graphene hydrogel (GN-GH), which can be readily scaled-up for mass production of nitrogen-doped graphene hydrogel by using organic amine and graphene oxide as precursors. The organic amine is not only as nitrogen sources to obtain the nitrogen-doped graphene but also as an important modification to control the assembly of graphene sheets in the 3D structures. Inner structure of the GN-GHs and the content of nitrogen in the graphene are easily adjusted by organic amine. Interestingly, it has been found that the supercapacitor performance of the typical product could be remarkably enhanced. Even at an ultrafast charge/discharge rate of 185.0A/g, a high power density of 205.0kW/kg can be obtained. In addition, at a current density of 100.0A/g, 95.2% of its capacitance was retained for 4000 cycles. The present nitrogen-doped graphene hydrogels may have potential applications as ultrahigh power density capacitors in the vehicle, lift and the other devices at high rates.
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► Macroscopic nitrogen-doped graphene hydrogels can be easily synthesized. ► The organic amine acts as nitrogen source and controls the assembly of graphene sheets. ► Inner structure of the nitrogen-doped graphene hydrogels and the content of nitrogen in the graphene can be easily adjusted by organic amine. ► The supercapacitor performance of the nitrogen-doped graphene hydrogels can be remarkably enhanced. ► A high power density of 205.0kW/kg can be reached even at an ultrafast charge/discharge rate of 185.0A/g.
We here report that miR‐17‐92 cluster is a novel target for p53‐mediated transcriptional repression under hypoxia. We found the expression levels of miR‐17‐92 cluster were reduced in hypoxia‐treated ...cells containing wild‐type p53, but were unchanged in hypoxia‐treated p53‐deficient cells. The repression of miR‐17‐92 cluster under hypoxia is independent of c‐Myc. Luciferase reporter assays mapped the region responding to p53‐mediated repression to a p53‐binding site in the proximal region of the miR‐17‐92 promoter. Chromatin immunoprecipitation (ChIP), Re‐ChIP and gel retardation assays revealed that the binding sites for p53‐ and the TATA‐binding protein (TBP) overlap within the miR‐17‐92 promoter; these proteins were found to compete for binding. Finally, we show that pri‐miR‐17‐92 expression correlated well with p53 status in colorectal carcinomas. Over‐express miR‐17‐92 cluster markedly inhibits hypoxia‐induced apoptosis, whereas blocked miR‐17‐5p and miR‐20a sensitize the cells to hypoxia‐induced apoptosis. These data indicated that p53‐mediated repression of miR‐17‐92 expression likely has an important function in hypoxia‐induced apoptosis, and thus further our understanding of the tumour suppressive function of p53.
We have synthesized a porous Mo‐based composite obtained from a polyoxometalate‐based metal–organic framework and graphene oxide (POMOFs/GO) using a simple one‐pot method. The MoO2@PC‐RGO hybrid ...material derived from the POMOFs/GO composite is prepared at a relatively low carbonization temperature, which presents a superior activity for the hydrogen‐evolution reaction (HER) in acidic media owing to the synergistic effects among highly dispersive MoO2 particles, phosphorus‐doped porous carbon, and RGO substrates. MoO2@PC‐RGO exhibits a very positive onset potential close to that of 20 % Pt/C, low Tafel slope of 41 mV dec−1, high exchange current density of 4.8×10−4 A cm−2, and remarkable long‐term cycle stability. It is one of the best high‐performance catalysts among the reported nonprecious metal catalysts for HER to date.
Nanocomposite catalyst: A novel Mo‐based catalyst for the hydrogen‐evolution reaction has been synthesized by directly carbonizing a composite obtained from polyoxometalate‐based metal–organic frameworks and graphene oxide at a relatively low temperature. The Mo‐based catalyst exhibits a positive onset potential, low Tafel slope, high exchange current density, and long‐term stability for the hydrogen‐evolution reaction in acidic media.
The general synthesis and control of the coordination environment of single‐atom catalysts (SACs) remains a great challenge. Herein, a general host–guest cooperative protection strategy has been ...developed to construct SACs by introducing polypyrrole (PPy) into a bimetallic metal–organic framework. As an example, the introduction of Mg2+ in MgNi‐MOF‐74 extends the distance between adjacent Ni atoms; the PPy guests serve as N source to stabilize the isolated Ni atoms during pyrolysis. As a result, a series of single‐atom Ni catalysts (named NiSA‐Nx‐C) with different N coordination numbers have been fabricated by controlling the pyrolysis temperature. Significantly, the NiSA‐N2‐C catalyst, with the lowest N coordination number, achieves high CO Faradaic efficiency (98 %) and turnover frequency (1622 h−1), far superior to those of NiSA‐N3‐C and NiSA‐N4‐C, in electrocatalytic CO2 reduction. Theoretical calculations reveal that the low N coordination number of single‐atom Ni sites in NiSA‐N2‐C is favorable to the formation of COOH* intermediate and thus accounts for its superior activity.
A host–guest cooperative protection strategy has been developed for constructing single‐atom catalysts (SACs), extending the range of available precursors from nitrogenous to non‐nitrogenous MOFs. The obtained Ni‐SACs (NiSA‐Nx‐C; x=2, 3, 4) at different pyrolysis temperatures feature varying nitrogen coordination numbers. The best of these catalysts, NiSA‐N2‐C, shows superior activity and selectivity in CO2 electroreduction.
Covalent organic frameworks (COFs) are an emerging type of crystalline and porous photocatalysts for hydrogen evolution, however, the overall water splitting activity of COFs is rarely known. In this ...work, we firstly realized overall water splitting activity of β-ketoamine COFs by systematically engineering N-sites, architecture, and morphology. By in situ incorporating sub-nanometer platinum (Pt) nanoparticles co-catalyst into the pores of COFs nanosheets, both Pt@TpBpy-NS and Pt@TpBpy-2-NS show visible-light-driven overall water splitting activity, with the optimal H
and O
evolution activities of 9.9 and 4.8 μmol in 5 h for Pt@TpBpy-NS, respectively, and a maximum solar-to-hydrogen efficiency of 0.23%. The crucial factors affecting the activity including N-sites position, nano morphology, and co-catalyst distribution were systematically explored. Further mechanism investigation reveals the tiny diversity of N sites in COFs that induces great differences in electron transfer as well as reaction potential barriers.
How the plasma membrane senses external heat-stress signals to communicate with chloroplasts to orchestrate thermotolerance remains elusive. We identified a quantitative trait locus,
Thermo-tolerance ...3
(
TT3
), consisting of two genes,
TT3.1
and
TT3.2
, that interact together to enhance rice thermotolerance and reduce grain-yield losses caused by heat stress. Upon heat stress, plasma membrane–localized E3 ligase TT3.1 translocates to the endosomes, on which TT3.1 ubiquitinates chloroplast precursor protein TT3.2 for vacuolar degradation, implying that TT3.1 might serve as a potential thermosensor. Lesser accumulated, mature TT3.2 proteins in chloroplasts are essential for protecting thylakoids from heat stress. Our findings not only reveal a
TT3.1-TT3.2
genetic module at one locus that transduces heat signals from plasma membrane to chloroplasts but also provide the strategy for breeding highly thermotolerant crops.
Heat tolerance in rice
Too much heat can damage a plant’s chloroplasts, driving yield down when temperatures exceed a crop’s normal tolerance. Zhang
et al
. identified a locus with two genes that together enhance rice thermotolerance. The ubiquitin ligase activity of Thermo-tolerance 3.1 (TT3.1) drove degradation of TT3.2, a chloroplast precursor protein that can trigger chloroplast damage in the context of heat stress. Together, these protein products respond to heat and control the damage. —PJH
A tag team of protein degradation protects rice plants from excess heat.
A convenient C−H amination of quinoxalin‐2‐ones has been developed. This transformation provides concise access to 3‐aminoquinoxalin‐2(1H)‐ones with a broad tolerance of functional groups, utilizing ...TMSN3 as an amino source under simple and mild conditions. The target 3‐aminoquinoxalin‐2(1H)‐ones are important intermediates for the synthesis of biologically active 3‐N‐substituted quinoxalin‐2‐one derivatives.
BackgroundAccurate identification of ovarian cancer (OC) is of paramount importance in clinical treatment success. Artificial intelligence (AI) is a potentially reliable assistant for the medical ...imaging recognition. We systematically review articles on the diagnostic performance of AI in OC from medical imaging for the first time. MethodsThe Medline, Embase, IEEE, PubMed, Web of Science, and the Cochrane library databases were searched for related studies published until August 1, 2022. Inclusion criteria were studies that developed or used AI algorithms in the diagnosis of OC from medical images. The binary diagnostic accuracy data were extracted to derive the outcomes of interest: sensitivity (SE), specificity (SP), and Area Under the Curve (AUC). The study was registered with the PROSPERO, CRD42022324611. FindingsThirty-four eligible studies were identified, of which twenty-eight studies were included in the meta-analysis with a pooled SE of 88% (95%CI: 85-90%), SP of 85% (82-88%), and AUC of 0.93 (0.91-0.95). Analysis for different algorithms revealed a pooled SE of 89% (85-92%) and SP of 88% (82-92%) for machine learning; and a pooled SE of 88% (84-91%) and SP of 84% (80-87%) for deep learning. Acceptable diagnostic performance was demonstrated in subgroup analyses stratified by imaging modalities (Ultrasound, Magnetic Resonance Imaging, or Computed Tomography), sample size (≤300 or >300), AI algorithms versus clinicians, year of publication (before or after 2020), geographical distribution (Asia or non Asia), and the different risk of bias levels (≥3 domain low risk or < 3 domain low risk). InterpretationAI algorithms exhibited favorable performance for the diagnosis of OC through medical imaging. More rigorous reporting standards that address specific challenges of AI research could improve future studies. FundingThis work was supported by the Natural Science Foundation of China (No. 82073647 to Q-JW and No. 82103914 to T-TG), LiaoNing Revitalization Talents Program (No. XLYC1907102 to Q-JW), and 345 Talent Project of Shengjing Hospital of China Medical University (No. M0268 to Q-JW and No. M0952 to T-TG).
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