Intelligent sensing systems have been fueled to make sense of visual sensory data to handle complex and difficult real-world sense-making challenges due to the rapid growth of computer vision and ...machine learning technologies ....
The exploring of catalysts with high‐efficiency and low‐cost for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the key issues for many renewable energy systems ...including fuel cells, metal–air batteries, and water splitting. Despite several decades pursuing, bifunctional oxygen catalysts with high catalytic performance at low‐cost, especially the one that could be easily scaled up for mass production are still missing and highly desired. Herein, a hybrid catalyst with NiCo alloy nanoparticles decorated on N‐doped carbon nanofibers is synthesized by a facile electrospinning method and postcalcination treatment. The hybrid catalyst NiCo@N‐C 2 exhibits outstanding ORR and OER catalytic performances, which is even surprisingly superior to the commercial Pt/C and RuO2 catalysts, respectively. The synergetic effects between alloy nanoparticles and the N‐doped carbon fiber are considered as the main contributions for the excellent catalytic activities, which include decreasing the intrinsic and charge transfer resistances, increasing CC, graphitic‐N/pyridinic‐N contents in the hybrid catalyst. This work opens up a new way to fabricate high‐efficient, low‐cost oxygen catalysts with high production.
NiCo alloy nanoparticles decorated on N‐doped carbon nanofibers as a highly active and durable oxygen electrocatalyst at low‐cost are synthesized and reported. The hybrid catalyst with suitable amount of NiCo alloy nanoparticles loading (NiCo@N‐C 2) gives the most outstanding oxygen reduction reaction and oxygen evolution reaction electrocatalytic performances, which is even surprisingly superior to the commercial Pt/C and RuO2 catalysts, respectively.
The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial reactions in energy conversion and storage systems including fuel cells, metal–air batteries, and electrolyzers. ...Developing low‐cost, high‐efficiency, and durable non‐noble bifunctional oxygen electrocatalysts is the key to the commercialization of these devices. Here, based on an in‐depth understanding of ORR/OER reaction mechanisms, recent advances in the development of non‐noble electrocatalysts for ORR/OER are reviewed. In particular, rational design for enhancing the activity and stability and scalable synthesis toward the large‐scale production of bifunctional electrocatalysts are highlighted. Prospects and future challenges in the field of oxygen electrocatalysis are presented.
Low‐cost and efficient bifunctional oxygen electrocatalysts are key to the commercialization of reversible fuel cells, metal–air batteries and electrolyzers. Herein, recent advances in the development of non‐noble bifunctional oxygen reduction reaction/oxygen evolution reaction electrocatalysts toward large‐scale production are presented, together with a discussion of the future challenges and prospects in this field.
Summary
Abscisic acid (ABA) plays a crucial role in the adaptation of young seedlings to environmental stresses. However, the role of epigenetic components and core transcriptional machineries in the ...effect of ABA on seed germination and seedling growth remain unclear.
Here, we show that a histone 3 lysine 4 (H3K4) demethylase, JMJ17, regulates the expression of ABA‐responsive genes during seed germination and seedling growth. Using comparative interactomics, WRKY40, a central transcriptional repressor in ABA signaling, was shown to interact with JMJ17. WRKY40 facilitates the recruitment of JMJ17 to the ABI5 chromatin, which removes gene activation marks (H3K4me3) from the ABI5 chromatin, thereby repressing its expression.
Additionally, WRKY40 represses the transcriptional activation activity of HY5, which can activate ABI5 expression by directly binding to its promoter. An increase in ABA concentrations decreases the affinity of WRKY40 for the ABI5 promoter. Thus, WRKY40 and JMJ17 are released from the ABI5 chromatin, activating HY5. The accumulated ABI5 protein further shows heteromeric interaction with HY5, and thus synergistically activates its own expression.
Our findings reveal a novel transcriptional switch, composed of JMJ17–WRKY40 and HY5–ABI5 modules, which regulates the ABA response during seed germination and seedling development in Arabidopsis.
The lithium–sulfur (Li–S) battery is one of the most promising high-energy-density secondary battery systems. However, it suffers from issues arising from its extremely complicated ...“solid–liquid–solid” reaction routes. In recent years, enormous advances have been made in optimizing Li–S batteries via the rational design of compositions and architectures. Nevertheless, a comprehensive and in-depth understanding of the practical reaction mechanisms of Li–S systems and their effect on the electrochemical performance is still lacking. Very recently, several important in situ optical spectroscopic techniques, including Raman, infrared and ultraviolet-visible spectroscopies, have been developed to monitor the real-time variations of the battery states, and a bridge linking the macroscopic electrochemical performance and microscopic architectures of the components has been set up, thus playing a critical role in scientifically guiding further optimal design of Li–S batteries. In this tutorial review, we provide a systematic summary of the state-of-the-art innovations in the characterization and optimal design of Li–S batteries with the aid of these in situ optical spectroscopic techniques, to guide a beginner to construct in situ optical spectroscopy electrochemical cells, and develop strategies for preventing long-chain polysulfide formation, dissolution and migration, thus alleviating the shuttle effect in Li–S batteries and improving the cell performances significantly.
Integrating network technology fully into traditional teaching can realize resource sharing to the greatest extent, so the establishment of distance education and network teaching platform has become ...the inevitable development of the time. The purpose of this paper is to build an embedded mobile teaching model based on network streaming media technology. The technology application, system composition and structure, realization process, and teaching method of the system are introduced in detail. The system energy consumption, bit rate of video information, and buffer technology were optimized, respectively. In this system, the energy consumption optimization method of mobile streaming media is adopted, and Central Processing Unit (CPU) resources are allocated reasonably according to the principle of maximizing rewards, so as to achieve the purpose of reducing power consumption. The results show that the system can effectively ensure the normal transmission of large multimedia information stream data through the network by using streaming media playback technology, and users can control the teaching process through interactive operation, which makes the network multimedia distance teaching based on streaming media develop in an all-round way and bring advanced teaching mode for education.
Under dehydration in plants, antagonistic activities of histone 3 lysine 4 (H3K4) methyl-transferase and histone demethylase maintain a dynamic and homeostatic state of gene expression by orientating ...transcriptional reprogramming toward growth or stress tolerance. However, the histone demethylase that specifically controls histone methylation homeostasis under dehydration stress remains unknown. Here, we document that a histone demethylase, JMJ17, belonging to the KDM5/JARID1 family, plays crucial roles in response to dehydration stress and abscisic acid (ABA) in Arabidopsis thaliana.
jmj17 loss-of-function mutants displayed dehydration stress tolerance and ABA hypersensitivity in terms of stomatal closure. JMJ17 specifically demethylated H3K4me1/2/3 via conserved iron-binding amino acids in vitro and in vivo. Moreover, H3K4 demethylase activity of JMJ17 was required for dehydration stress response.
Systematic combination of genome-wide chromatin immunoprecipitation coupled with massively parallel DNA sequencing (ChIP-seq) and RNA-sequencing (RNA-seq) analyses revealed that a loss-of-function mutation in JMJ17 caused an ectopic increase in genome-wide H3K4me3 levels and activated a plethora of dehydration stress-responsive genes. Importantly, JMJ17 bound directly to the chromatin of OPEN STOMATA 1 (OST1) and demethylated H3K4me3 for the regulation of OST1 mRNA abundance, thereby modulating the dehydration stress response.
Our results demonstrate a new function of a histone demethylase under dehydration stress in plants.
The insect gut microbiota has been shown to contribute to the host's digestion, detoxification, development, pathogen resistance, and physiology. However, there is poor information about the ranking ...of these roles. Most of these results were obtained with cultivable bacteria, whereas the bacterial physiology may be different between free-living and midgut-colonizing bacteria. In this study, we provided both proteomic and genomic evidence on the ranking of the roles of gut bacteria by investigating the anal droplets from a weevil, Cryptorhynchus lapathi.
The gut lumen and the anal droplets showed qualitatively and quantitatively different subsets of bacterial communities. The results of 16S rRNA sequencing showed that the gut lumen is dominated by Proteobacteria and Bacteroidetes, whereas the anal droplets are dominated by Proteobacteria. From the anal droplets, enzymes involved in 31 basic roles that belong to 7 super roles were identified by Q-TOF MS. The cooperation between the weevil and its gut bacteria was determined by reconstructing community pathway maps, which are defined in this study. A score was used to rank the gut bacterial roles. The results from the proteomic data indicate that the most dominant role of gut bacteria is amino acid biosynthesis, followed by protein digestion, energy metabolism, vitamin biosynthesis, lipid digestion, plant secondary metabolite (PSM) degradation, and carbohydrate digestion, while the order from the genomic data is amino acid biosynthesis, vitamin biosynthesis, lipid digestion, energy metabolism, protein digestion, PSM degradation, and carbohydrate digestion. The PCA results showed that the gut bacteria form functional groups from the point of view of either the basic role or super role, and the MFA results showed that there are functional variations among gut bacteria. In addition, the variations between the proteomic and genomic data, analyzed with the HMFA method from the point of view of either the bacterial community or individual bacterial species, are presented.
The most dominant role of gut bacteria is essential nutrient provisioning, followed by digestion and detoxification. The weevil plays a pioneering role in diet digestion and mainly digests macromolecules into smaller molecules which are then mainly digested by gut bacteria.
The COVID-19 pandemic continues to spread throughout the world with an urgent need for a safe and protective vaccine to effectuate herd protection and control the spread of SARS-CoV-2. Here, we ...report the development of a SARS-CoV-2 subunit vaccine (NVX-CoV2373) from the full-length spike (S) protein that is stable in the prefusion conformation. NVX-CoV2373 S form 27.2-nm nanoparticles that are thermostable and bind with high affinity to the human angiotensin-converting enzyme 2 (hACE2) receptor. In mice, low-dose NVX-CoV2373 with saponin-based Matrix-M adjuvant elicit high titer anti-S IgG that blocks hACE2 receptor binding, neutralize virus, and protects against SARS-CoV-2 challenge with no evidence of vaccine-associated enhanced respiratory disease. NVX-CoV2373 also elicits multifunctional CD4
and CD8
T cells, CD4
follicular helper T cells (Tfh), and antigen-specific germinal center (GC) B cells in the spleen. In baboons, low-dose levels of NVX-CoV2373 with Matrix-M was also highly immunogenic and elicited high titer anti-S antibodies and functional antibodies that block S-protein binding to hACE2 and neutralize virus infection and antigen-specific T cells. These results support the ongoing phase 1/2 clinical evaluation of the safety and immunogenicity of NVX-CoV2373 with Matrix-M (NCT04368988).
Trace element geochemistry of pyrite is widely used to monitor ore-forming processes of various types of deposits, but its application to skarn mineral systems is not well constrained due to the ...multi-stage nature and complex associated mineral assemblages for skarn-type pyrite. The Jiguanzui skarn Au-Cu deposit in the Middle-Lower Yangtze River Valley Metallogenic Belt (Eastern China) is characterized by abundant pyrite that formed in the main-ore (Py1), late-ore (Py2), and post-ore (Py3) stages, which makes it ideal for unraveling skarn ore-fluid evolution. Specifically, Py1 is composed of quartz-pyrite (Py1a), quartz-calcite-pyrite (Py1b), quartz-sericite-pyrite (Py1c), quartz-chlorite±epidote-pyrite (Py1d), and quartz-K-feldspar-pyrite (Py1e), among which Py1a is the most widespread. Py2 comprises calcite-pyrite (Py2a) and calcite-K-feldspar-pyrite (Py2b), and Py3 comprise bird's-eye pyrite (Py3a) and fingerprint-like pyrite (Py3b). The varying Co/Ni ratios (mostly >2) and coexistence with hydrothermal minerals (quartz, calcite, K-feldspar, chlorite, and epidote) reveal the hydrothermal origin of Py1 and Py2. The Co/Ni (0.97-7.30), Cu/Ni (8.94-186), and As/Ni (0.80-11.7) ratios, and the high trace-element contents indicate that Py3a may have been genetically linked to the waning magmatic-hydrothermal system and increasing meteoric fluid influx. Py1 generally has higher Co-Ni-Se but lower Zn-As-Mo contents than Py2. Py1 in the orebodies also has higher Cu-Au contents than Py2, consistent with the formation of Py1 during the main Au-Cu ore stage. During the ore-fluid evolution, meteoric water input and abundant galena formation in the late-ore calcite-sulfide stage may have controlled the decreasing Se-Co-Ni contents from Py1 to Py2, while the fluid cooling and pH rise (caused by acidic fluid-carbonate rock reactions) may have increased the As-Zn-Mo contents from Py1 to Py2. Py1a in the orebodies has higher As-Ag-Te, but lower Co-Ni-Se contents than Py1a in the wallrocks. The decompression and phase separation (fluid boiling) by extensive hydraulic fracturing may have caused the higher temperature, pH, and fO2 for the Py1a-forming fluids in the orebodies (than those in the wallrocks). Such fluid physicochemical differences may have been the main controlling factor on trace element spatial variations of Py1a. More importantly, the spatial variation of these trace elements in Py1a provides insights for using pyrite trace element geochemistry in skarn mineral exploration.
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