Herein, an effective tandem catalysis strategy is developed to improve the selectivity of the CO2RR towards C2H4 by multiple distinct catalytic sites in local vicinity. An earth‐abundant ...elements‐based tandem electrocatalyst PTF(Ni)/Cu is constructed by uniformly dispersing Cu nanoparticles (NPs) on the porphyrinic triazine framework anchored with atomically isolated nickel–nitrogen sites (PTF(Ni)) for the enhanced CO2RR to produce C2H4. The Faradaic efficiency of C2H4 reaches 57.3 % at −1.1 V versus the reversible hydrogen electrode (RHE), which is about 6 times higher than the non‐tandem catalyst PTF/Cu, which produces CH4 as the major carbon product. The operando infrared spectroscopy and theoretic density functional theory (DFT) calculations reveal that the local high concentration of CO generated by PTF(Ni) sites can facilitate the C−C coupling to form C2H4 on the nearby Cu NP sites. The work offers an effective avenue to design electrocatalysts for the highly selective CO2RR to produce multicarbon products via a tandem route.
An effective tandem catalysis strategy is developed to enhance the selectivity of the CO2 electroreduction reaction towards C2H4 with a 6‐fold increase in comparison with that of the non‐tandem catalysts. The local high concentration of CO generated by atomically isolated nickel–nitrogen sites PTF(Ni) sites can facilitate the C−C coupling to form C2H4 on the nearby Cu NP sites, thus switching from CH4 to C2H4 production with a Faradaic efficiency of 57.3 %.
The electrocatalytic conversion of CO2 into value‐added chemicals is a promising approach to realize a carbon‐energy balance. However, low current density still limits the application of the CO2 ...electroreduction reaction (CO2RR). Metal–organic frameworks (MOFs) are one class of promising alternatives for the CO2RR due to their periodically arranged isolated metal active sites. However, the poor conductivity of traditional MOFs usually results in a low current density in CO2RR. We have prepared conductive two‐dimensional (2D) phthalocyanine‐based MOF (NiPc‐NiO4) nanosheets linked by nickel‐catecholate, which can be employed as highly efficient electrocatalysts for the CO2RR to CO. The obtained NiPc‐NiO4 has a good conductivity and exhibited a very high selectivity of 98.4 % toward CO production and a large CO partial current density of 34.5 mA cm−2, outperforming the reported MOF catalysts. This work highlights the potential of conductive crystalline frameworks in electrocatalysis.
Nickel phthalocyanine molecules as active sites were installed into nickel‐catecholate‐linked 2D conductive metal–organic framework nanosheets for efficient CO2 electroreduction with nearly 100 % CO selectivity.
The electroreduction of CO2 to value‐added chemicals such as CO is a promising approach to realize carbon‐neutral energy cycle, but still remains big challenge including low current density. Covalent ...organic frameworks (COFs) with abundant accessible active single‐sites can offer a bridge between homogeneous and heterogeneous electrocatalysis, but the low electrical conductivity limits their application for CO2 electroreduction reaction (CO2RR). Here, a 2D conductive Ni‐phthalocyanine‐based COF, named NiPc‐COF, is synthesized by condensation of 2,3,9,10,16,17,23,24‐octa‐aminophthalocyaninato Ni(II) and tert‐butylpyrene‐tetraone for highly efficient CO2RR. Due to its highly intrinsic conductivity and accessible active sites, the robust conductive 2D NiPc‐COF nanosheets exhibit very high CO selectivity (>93%) in a wide range of the applied potentials of −0.6 to −1.1 V versus the reversible hydrogen electrode (RHE) and large partial current density of 35 mA cm−2 at −1.1 V versus RHE in aqueous solution that surpasses all the conventional COF electrocatalysts. The robust NiPc‐COF that is bridged by covalent pyrazine linkage can maintain its CO2RR activity for 10 h. This work presents the implementation of the conductive COF nanosheets for CO2RR and provides a strategy to enhance energy conversion efficiency in electrocatalysis.
A conductive nickelophthalocyanine‐based 2D covalent organic framework is synthesized and employed as a robust and efficient electrocatalyst for CO2 electroreduction reaction, providing a new route to design highly efficient porous framework materials for the enhanced electrocatalysis via improving electrical conductivity.
Solvent effect plays an important role in catalytic reaction, but there is little research and attention on it in electrochemical CO2 reduction reaction (eCO2RR). Herein, we report a stable ...covalent‐organic framework (denoted as PcNi‐im) with imidazole groups as a new electrocatalyst for eCO2RR to CO. Interestingly, compared with neutral conditions, PcNi‐im not only showed high Faraday efficiency of CO product (≈100 %) under acidic conditions (pH ≈ 1), but also the partial current density was increased from 258 to 320 mA cm−2. No obvious degradation was observed over 10 hours of continuous operation at the current density of 250 mA cm−2. The mechanism study shows that the imidazole group on the framework can be protonated to form an imidazole cation in acidic media, hence reducing the surface work function and charge density of the active metal center. As a result, CO poisoning effect is weakened and the key intermediate *COOH is also stabilized, thus accelerating the catalytic reaction rate.
l-Tryptophan (Trp) metabolites and related neurotransmitters play crucial roles in physiological functions, and their imbalances are implicated in the pathology of depression, Alzheimer's disease and ...other diseases. Measurement of Trp metabolites and related neurotransmitters possesses a great potential to elucidate the disease mechanisms and evaluate the outcomes of therapeutic interventions. A simple, rapid, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of Trp, l-kynurenine (Kyn), kynurenic acid (Kyna), 3-hydroxykynurenine (3-HK), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), norepinephrine (NE), l-glutamic acid (Glu), γ-aminobutyric acid (GABA) and acetylcholine (ACh) in mice serum and the brain tissues in a single chromatographic run. Samples were spiked with the internal standard, mixed with trifluoroacetic acid to precipitate protein and analyzed by LC-MS/MS. Chromatographic separation was achieved using a Restek Ultra Aqueous C18 column in combination with a gradient elution within 8 min. Mass spectrometric detection was performed using multiple reaction monitoring with electrospray ionization source in positive mode. The method exhibited good selectivity and correlation coefficient values for the calibration curves of each analyte were >0.99. The limit of detection and quantification ranged from 0.96 to 24.48 nmol/L and 3.42 to 244.82 nmol/L, respectively. The intra- and inter-day precision were ≤13.92%. All analytes were stable in prepared samples at room temperature in the autosampler for 24 h. This method was successfully applied to the analysis of biological samples from control and chronic mild stress (CMS) induced depression mice. It was found that Kyn and 3-HK pathways were enhanced by CMS, while the levels of Trp, Kyna, 5-HIAA, Glu, GABA and ACh were significantly reduced. The changes in 5-HT and NE levels were not uniform in the periphery and the brain. This method can therefore be applied to analyze Trp metabolites and related neurotransmitters levels to monitor disease states, study the mechanisms and outcomes of therapeutic interventions.
•Simultaneous quantification of tryptophan metabolites and related neurotransmitters•The validated method shows high selectivity, sensitivity and precision.•Analytes were successfully detected in control and chronic mild stress mice.
SUMMARY
The self‐splicing of group II introns during RNA processing depends on their catalytic structure and is influenced by numerous factors that promote the formation of that structure through ...direct binding. Here we report that C‐to‐U editing at a specific position in two nad7 introns is essential to splicing, which also implies that the catalytic activity of non‐functional group II introns could be restored by editing. We characterized a maize (Zea mays) mutant, dek46, with a defective kernel phenotype; Dek46 encodes a pentatricopeptide repeat DYW protein exclusively localized in mitochondria. Analyses of the coding regions of mitochondrial transcripts did not uncover differences in RNA editing between dek46 mutant and wild‐type maize, but showed that splicing of nad7 introns 3 and 4 is severely reduced in the mutant. Furthermore, editing at nucleotide 22 of domain 5 (D5‐C22) of both introns is abolished in dek46. We constructed chimeric introns by swapping D5 of P.li.LSUI2 with D5 of nad7 intron 3. In vitro splicing assays indicated that the chimeric intron containing D5‐U22 can be self‐spliced, but the one containing D5‐C22 cannot. These results indicate that DEK46 functions in the C‐to‐U editing of D5‐C22 of both introns, and the U base at this position is critical to intron splicing.
Significance Statement
How mitochondrial introns are spliced is a fundamental question in plant biology. Through characterization of a dek46 mutant and in vitro splicing analyses, this study demonstrates that a single C‐to‐U editing event in the nad7 introns 3 and 4 domain 5 is critical to the intron splicing and kernel development of maize, possibly through maintaining the intron in a catalytic configuration. This study suggests the important role of intron editing to mitochondrial intron splicing.
The highly selective production of reduced multicarbon products with long‐term durability for CO2 electroreduction reaction (CO2RR) using clean and renewable electricity is currently a major ...challenge. Copper nanoparticles (Cu NPs) are exceptionally advantageous for CO2RR to yield multielectron transfer chemical products such as ethylene and ethanol. However, Cu NPs for CO2RR generally require high overpotential to produce multiple electron transfer C2+ products with poor stability. Herein, an imidazolium‐functionalized covalent triazine framework (ICTF) stabilized Cu NPs (Cu/ICTF) for the enhanced CO2RR to produce ethylene is reported. The imidazolium groups in the cationic ICTF not only can enhance CO2 capture capacity and lower the energetic barrier to activate CO2, but also the in situ formed N‐heterocyclic carbenes (NHC) could stabilize Cu NPs to prevent their deactivation. Thus, the Cu/ICTF demonstrated higher selectivity (35 %) for the electroreduction of CO2 to ethylene with larger partial current density of ethylene (4.14 mA cm−2) over the unmodified neutral CTF stabilized Cu NPs (Cu/CTF) with 29 % Faradaic efficiency (FE) of ethylene and current density of 3.69 mA cm−2. Moreover, the active sites could be stabilized by the in situ produced NHC in ICTF and the current density and C2H4 FE of Cu/ICTF50 were almost maintained after 10 h continuous electrolysis experiment, while the C2H4 FE of Cu/CTF50 were lost ca. 42 % of its original value after 7 h. This strategy provides a facile approach to stabilize active sites for CO2RR and may bring new inspiration to apply in energy storage and conversion.
CO2 electroreduction: An imidazolium‐functionalized covalent triazine framework (ICTF) stabilized Cu NPs (Cu/ICTF) for the enhanced CO2RR to produce ethylene was reported. The imidazolium groups in the cationic ICTF not only can enhance CO2 capture capacity and lower energetic barrier to activate CO2, but also the in situ formed N‐heterocyclic carbenes (NHC) could stabilize Cu NPs to prevent their deactivation.
SUMMARY
Ribosome assembly factors guide the complex process by which ribosomal proteins and the ribosomal RNAs form a functional ribosome. However, the assembly of plant plastid ribosomes is poorly ...understood. In the present study, we discovered a maize (Zea mays) plastid ribosome assembly factor based on our characterization of the embryo defective 15 (emb15) mutant. Loss of function of Emb15 retards embryo development at an early stage, but does not substantially affect the endosperm, and causes an albino phenotype in other genetic backgrounds. EMB15 localizes to plastids and possesses a ribosome maturation factor M (RimM) domain in the N‐terminus and a predicted UDP‐GlcNAc pyrophosphorylase domain in the C‐terminus. The EMB15 RimM domain originated in bacteria and the UDP‐GlcNAc pyrophosphorylase domain originated in fungi; these two domains came together in the ancestor of land plants during evolution. The N‐terminus of EMB15 complemented the growth defect of an Escherichia coli strain with a RimM deletion and rescued the albino phenotype of emb15 homozygous mutants. The RimM domain mediates the interaction between EMB15 and the plastid ribosomal protein PRPS19. Plastid 16S rRNA maturation is also significantly impaired in emb15. These observations suggest that EMB15 functions in maize seed development as a plastid ribosome assembly factor, and the C‐terminal domain is not important under normal conditions.
Significance Statement
Ribosome assembly is guided by many assembly factors. Plastid ribosome assembly is important to embryogenesis or plant development, but little is known about this process. This study identifies a protein that is essential for the assembly of maize plastid ribosomes, discovers the major function of an evolutionary conserved protein that has not been studied in plants before, and expands our understanding of plastid ribosome assembly and maize kernel development.
Benzo a pyrene (BaP), a potent carcinogen, has been proved that it has toxicological effects via activation the aryl hydrocarbon receptor (AhR) pathway. AhR can participate in regulating lipogenesis ...and lipolysis. This topic will verify whether BaP regulates lipid metabolism via AhR.
(1) C57BL/6 mice were gavaged with BaP for 12 weeks to detect serum lipids, glucose tolerance, and insulin resistance. Morphological changes in white adipose tissue (WAT) were detected by Hematoxylin and Eosin staining. The mRNA expression levels of adipogenesis-related factors included recombinant human CCAAT/enhancer binding protein alpha (C/EBPα), peroxisome proliferator-activated receptor gamma (PPARγ), and fatty acid binding protein 4 (FABP
) and inflammatory factors included nuclear factor kappa-B (NF-κB), monocyte chemotactic protein-1 (MCP-1), and tumor necrosis factor alpha (TNF-α) were detected using PCR. (2) Neutral lipid content changes in differentiated 3 T3-L1 adipocytes treated with BaP with and w/o AhR inhibitor were detected by Oil red staining. The protein expression levels of adipogenesis- and decomposition-related factors included PPARγ coactivator-1 alpha (PGC-1α), and peroxisome proliferation-activated receptor alpha (PPARα) were detected using western blotting. The mRNA expression levels of inflammatory factors were detected using PCR.
(1) BaP inhibited body weight gain, decreased lipid content, increased lipid levels, and decreased glucose tolerance and insulin tolerance in mice; (2) BaP reduced the expressions of C/EBPα, PPARγ, FABP
, PGC-1α, and PPARα and increased the expressions of NF-κB, MCP-1, and TNF-α by activating AhR.
BaP inhibit fat synthesis and oxidation while inducing inflammation by activating AhR, leading to WAT dysfunction and causing metabolic complications.
The potato tuber moth, Phthorimaea operculella, is the most damaging potato pest in the world and is difficult to control as the larvae are internal feeders in the foliage and tubers. ...Entomopathogenic fungi that colonize plants as endophytes have lethal and sublethal pathological effects on insect pests. We show that Beauveria bassiana colonizes the aerial parts of potato plants endophytically after inoculation through soil drenching. Endophytic B. bassiana persisted in potato foliage for more than 50 days postinoculation. Bioassays indicated that foliage of B. bassiana‐inoculated potato plants were pathogenic against larvae of P. operculella. Sublethal experiments indicated that B. bassiana negatively affected the growth, development, and reproduction of P. operculella. Development experiments showed that the weight of P. operculella pupae reared on B. bassiana‐colonized potato plants (4.25 mg) was significantly less than that of those reared on uninoculated control plants (8.89 mg). Compared with newly eclosed larvae fed on control plants, those fed on B. bassiana‐inoculated plants had significantly lower survivorship, with only 17.8% developing to the adult stage. Oviposition of P. operculella females reared on B. bassiana endophytically colonized plants was significantly lower (35 eggs/female) than of those reared on uninoculated plants (115 eggs/female). This study demonstrates that endophytic B. bassiana can be a potential biological control agent for the control and management of P. operculella. Comparing pupal weights of P. operculella reared on potato plants inoculated with the B. bassiana strain GZGY‐1‐3 and on untreated control plants, pupae from the control plants were significantly heavier than those from treated plants.
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