The oxygen reduction reaction (ORR) on transition single‐atom catalysts (SACs) is sustainable in energy‐conversion devices. However, the atomically controllable fabrication of single‐atom sites and ...the sluggish kinetics of ORR have remained challenging. Here, we accelerate the kinetics of acid ORR through a direct O−O cleavage pathway through using a bi‐functional ligand‐assisted strategy to pre‐control the distance of hetero‐metal atoms. Concretely, the as‐synthesized Fe−Zn diatomic pairs on carbon substrates exhibited an outstanding ORR performance with the ultrahigh half‐wave potential of 0.86 V vs. RHE in acid electrolyte. Experimental evidence and density functional theory calculations confirmed that the Fe−Zn diatomic pairs with a specific distance range of around 3 Å, which is the key to their ultrahigh activity, average the interaction between hetero‐diatomic active sites and oxygen molecules. This work offers new insight into atomically controllable SACs synthesis and addresses the limitations of the ORR dissociative mechanism.
The dual single‐atom carbon electrocatalysts are rationally optimized for the interatomic distance and promote an effective oxygen reduction reaction via the direct oxygen‐oxygen bond cleavage mechanism in acid electrolyte. The specific distance of dual‐hetero single‐atom pairs weakens and destabilizes the bond energy of the oxygen‐oxygen bond through the strong and evenly bilateral electron and charge transfer capabilities.
Nonsynonymous mutations change the protein sequences and are frequently subjected to natural selection. The same goes for nonsense mutations that introduce pre-mature stop codons into CDSs (coding ...sequences). Synonymous mutations, however, are intuitively thought to be functionally silent and evolutionarily neutral. Now researchers know that the optimized synonymous codon usage is advantageous in the speedy mRNA translation process. With the advent of NGS technique, the explosion of NGS data generated from the tumor tissues help researchers identify driver mutations in cancer-related genes, but relatively less attention is paid to the SNP data in healthy human populations when studying cancer.
Here, we analyzed the publically available human SNPs. We classified these SNPs according to their functional and evolutionary categories. By simply dividing the human genes into cancer-related genes and other genes, we compared the features of nonsynonymous, synonymous and nonsense mutations in these two gene sets from multiple aspects.
We provided lines of evidence that the nonsynonymous, synonymous and nonsense mutations in cancer-related genes undergo stronger purifying selection when compared to the expected pattern in other genes. The lower nonsynonymous to synonymous ratio observed in cancer-related genes suggests the suppression of amino acid substitutions in these genes. The synonymous SNPs, after excluding those in splicing regions, exhibit preferred changes in codon usage and higher codon frequencies in cancer-related genes compared to other genes, indicating the constraint exerted on these mutations. Nonsense mutations are less frequent and located closer to stop codons in cancer-related genes than in other genes, which putatively minimize their deleterious effects.
Our study demonstrated the evolutionary constraint on mutations in CDS of cancer-related genes without the requirement of data from cancer tissues or patients. Our work provides novel perspectives on interpreting the constraint on mutations in cancer-related genes. We reveal extra constraint on synonymous mutations in cancer-related genes which is related to codon usage bias and is in addition to the splicing effect.
Electrochemical production of H
2
O
2
from O
2
using simulated seawater provides a promising alternative to the energy-intensive industrial anthraquinone process. In this study, a flow cell system is ...built for electrocatalytic production of H
2
O
2
under an air atmosphere in simulated seawater using cobalt single-atom catalysts (Co SACs). The Co SACs can achieve a high H
2
O
2
production rate of 3.4 mol g
catalyst
−1
h
−1
under an air flow at a current density of 50 mA cm
geo
−2
and long-term stability over 24 h in 0.5 M NaCl. It is found that Co-N
5
rather than the Co-N
4
structure in Co SACs is the main active site for H
2
O
2
formation in the two-electron oxygen reduction reaction (ORR) pathway. It also shows high chloride-endurability without inhibition of the ORR process in simulated seawater. The fast production of H
2
O
2
on Co-N
5
sites in a flow cell provides a promising path of electrocatalytic oxygen reduction in simulated seawater, eventually converting ubiquitous air and seawater towards energy sustainability.
Sustainable production of H
2
O
2
is boosted by oxygen reduction reaction on Co-N
5
sites in a flow cell in simulated seawater.
Clean energy has become an important topic in recent decades because of the serious global issues related to the development of energy, such as environmental contamination, and the intermittence of ...the traditional energy sources. Creating new battery‐related energy storage facilities is an urgent subject for human beings to address and for solutions for the future. Compared with lithium‐based batteries, sodium–ion batteries have become the new focal point in the competition for clean energy solutions and have more potential for commercialization due to the huge natural abundance of sodium. Nevertheless, sodium–ion batteries still exhibit some challenges, like inferior electrochemical performance caused by the bigger ionic size of Na+ ions, the detrimental volume expansion, and the low conductivity of the active materials. To solve these issues, nanocomposites have recently been applied as a new class of electrodes to enhance the electrochemical performance in sodium batteries based on advantages that include the size effect, high stability, and excellent conductivity. In this Review, the recent development of nanocomposite materials applied in sodium–ion batteries is summarized, and the existing challenges and the potential solutions are presented.
To explore electrode materials with long cycle life and high energy density, a wide range of nanocomposites have been applied to the anodes and cathodes of sodium batteries. Due to the advantages of nanoscale composites, there have been great improvements in the electrical performance of sodium–ion batteries. The development of nanocomposite materials for sodium–ion batteries is reviewed here.
This case series uses patient hospital data to summarize the clinical presentation and laboratory and imaging findings of 13 patients with confirmed 2019-nCoV infection admitted to hospitals in ...Beijing in January 2020.
Room‐temperature sodium–sulfur (RT‐Na/S) batteries possess high potential for grid‐scale stationary energy storage due to their low cost and high energy density. However, the issues arising from the ...low S mass loading and poor cycling stability caused by the shuttle effect of polysulfides seriously limit their operating capacity and cycling capability. Herein, sulfur‐doped graphene frameworks supporting atomically dispersed 2H‐MoS2 and Mo1 (S@MoS2‐Mo1/SGF) with a record high sulfur mass loading of 80.9 wt.% are synthesized as an integrated dual active sites cathode for RT‐Na/S batteries. Impressively, the as‐prepared S@MoS2‐Mo1/SGF display unprecedented cyclic stability with a high initial capacity of 1017 mAh g−1 at 0.1 A g−1 and a low‐capacity fading rate of 0.05% per cycle over 1000 cycles. Experimental and computational results including X‐ray absorption spectroscopy, in situ synchrotron X‐ray diffraction and density‐functional theory calculations reveal that atomic‐level Mo in this integrated dual‐active‐site forms a delocalized electron system, which could improve the reactivity of sulfur and reaction reversibility of S and Na, greatly alleviating the shuttle effect. The findings not only provide an effective strategy to fabricate high‐performance dual‐site cathodes, but also deepen the understanding of their enhancement mechanisms at an atomic level.
An integrated dual‐active‐site cathode is developed by wreathing monolayered MoS2 and Mo1 on sulfur‐doped graphene frameworks for high‐performance room‐temperature sodium–sulfur batteries. The constructed atomic level MoS2‐Mo1 with delocalized electron effects facilitates substantial charge transfer and a completely reversible reaction between S and Na, thus alleviating the shuttle effect.
The low-cost room-temperature sodium-sulfur battery system is arousing extensive interest owing to its promise for large-scale applications. Although significant efforts have been made, resolving low ...sulfur reaction activity and severe polysulfide dissolution remains challenging. Here, a sulfur host comprised of atomic cobalt-decorated hollow carbon nanospheres is synthesized to enhance sulfur reactivity and to electrocatalytically reduce polysulfide into the final product, sodium sulfide. The constructed sulfur cathode delivers an initial reversible capacity of 1081 mA h g
with 64.7% sulfur utilization rate; significantly, the cell retained a high reversible capacity of 508 mA h g
at 100 mA g
after 600 cycles. An excellent rate capability is achieved with an average capacity of 220.3 mA h g
at the high current density of 5 A g
. Moreover, the electrocatalytic effects of atomic cobalt are clearly evidenced by operando Raman spectroscopy, synchrotron X-ray diffraction, and density functional theory.
Both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are crucial to water splitting, but require alternative active sites. Now, a general π‐electron‐assisted strategy to ...anchor single‐atom sites (M=Ir, Pt, Ru, Pd, Fe, Ni) on a heterogeneous support is reported. The M atoms can simultaneously anchor on two distinct domains of the hybrid support, four‐fold N/C atoms (M@NC), and centers of Co octahedra (M@Co), which are expected to serve as bifunctional electrocatalysts towards the HER and the OER. The Ir catalyst exhibits the best water‐splitting performance, showing a low applied potential of 1.603 V to achieve 10 mA cm−2 in 1.0 m KOH solution with cycling over 5 h. DFT calculations indicate that the Ir@Co (Ir) sites can accelerate the OER, while the Ir@NC3 sites are responsible for the enhanced HER, clarifying the unprecedented performance of this bifunctional catalyst towards full water splitting.
HER and OER! The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are crucial to water splitting, but require alternative active sites. Now, a general π‐electron‐assisted strategy to anchor single‐atom sites (M=Ir, Pt, Ru, Pd, Fe, Ni) on a heterogeneous support is reported. The M atoms can simultaneously anchor on two distinct domains of the hybrid support, four‐fold N/C atoms, and centers of Co octahedra.
Convolutional neural networks have recently demonstrated high-quality reconstruction for single image super-resolution. However, existing methods often require a large number of network parameters ...and entail heavy computational loads at runtime for generating high-accuracy super-resolution results. In this paper, we propose the deep Laplacian Pyramid Super-Resolution Network for fast and accurate image super-resolution. The proposed network progressively reconstructs the sub-band residuals of high-resolution images at multiple pyramid levels. In contrast to existing methods that involve the bicubic interpolation for pre-processing (which results in large feature maps), the proposed method directly extracts features from the low-resolution input space and thereby entails low computational loads. We train the proposed network with deep supervision using the robust Charbonnier loss functions and achieve high-quality image reconstruction. Furthermore, we utilize the recursive layers to share parameters across as well as within pyramid levels, and thus drastically reduce the number of parameters. Extensive quantitative and qualitative evaluations on benchmark datasets show that the proposed algorithm performs favorably against the state-of-the-art methods in terms of run-time and image quality.
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