Electro-triggered Joule heating method to synthesize single-phase CuNi nano-alloy catalyst for efficient electrocatalytic nitrate reduction toward ammonia

Electrochemical nitrate reduction reaction(NO_(3)RR)has great potential for ammonia(NH_(3))synthesis benefiting from its environmental friendliness and sustainability.Cu-based alloys with elemental diversity and adsorption tunability are widely used as electrocatalyst to lower the reaction overpotential for NO_(3)RR catalysis.However,phase separation commonly found in alloys leads to uneven distribution of elements,which limits the possibility of further optimizing the catalytic activity.Herein,an electrotriggered Joule heating method,possessing unique superiority of flash heating and cooling that lead to well-dispersed nanoparticles and uniform mixing of various elements,was adopted to synthesize a single-phase CuNi nano-alloy catalyst evenly dispersed on carbon fiber paper,CFP-Cu_(1)Ni_(1),which exhibited a more positive NO_(3)RR initial potential of 0.1 V versus reversible hydrogen electrode(vs.RHE)than that of pure copper nanoparticles at 10 mA·cm^(−2)in 0.5 mol·L^(−1)Na_(2)SO_(4)+0.1 mol·L^(−1)KNO_(3)solution.Importantly,CFP-Cu_(1)Ni_(1) presented high electrocatalytic activity with a Faradaic efficiency of 95.7%and NH_(3)yield rate of 180.58μmol·h^(−1)·cm^(−2)(2550μmol·h^(−1)·mg_(cat)^(−1))at−0.22 V vs.RHE.Theoretical calculations showed that alloying Cu with Ni into single-phase caused an upshift of its d-band center,which promoted the adsorption of NO_(3)−and weakened the adsorption of NH_(3).Moreover,the competitive adsorption of hydrogen ions was restrained until−0.24 V.This work offers a rational design concept with clear guidance for rapid synthesis of uniformly dispersed single-phase nano-alloy catalyst for efficient electrochemical NO_(3)RR toward ammonia.

Recent Advances in Stability Improvement Strategies of M-N_(x)/C Catalysts Towards Oxygen Reduction Reaction

Although fuel cells possess advantages of high energy conversion efficiency and zero-carbon emission,their large-scale commercialization is restricted by expensive and scarce platinum(Pt)catalysts.Metal-nitrogen-carbon(M-Nx/C)catalysts are hailed as the most promising candidates to replace Pt due to their considerable oxygen reduction reaction(ORR)activity and low cost.Despite tremendous progress in terms of active site identification and activity improvement being achieved in the past few decades,the M-Nx/C catalysts still suffer from insufficient durability,which drastically limits their practical application.In this regard,understanding degradation mechanisms and customizing stabilization strategies are of significant importance yet challengeable.In this review,we summarize the recent advances in the stability improvement of M-Nx/C catalysts.The stability test protocols of the M-Nx/C are firstly introduced.Subsequently,with the combination of advanced ex situ and in situ characterization techniques and density functional theory calculation,we present a comprehensive overview of the main degradation mechanisms during ORR process.Aiming at these deactivation issues,a variety of novel improvement strategies are developed to enhance the stability of M-Nx/C.Finally,the current challenges and prospects to design highly stable M-Nx/C catalysts are also proposed.

A viral protein orchestrates rice ethylene signaling to coordinate viral infection and insect vector-mediated transmission

Arthropod-borne viruses cause serious threats to human health and global agriculture by rapidly spreading via insect vectors. Southern rice black-streaked dwarf virus (SRBSDV) is the most damaging rice-infecting virus that is frequently transmitted by planthoppers. However, the molecular mechanisms underlying its propagation in the host plants and epidemics in the field are largely unknown. Here, we showed that the SRBSDV-encoded P6 protein is a key effector that regulates rice ethylene signaling to coordinate viral infection and transmission. In early SRBSDV infection, P6 interacts with OsRTH2 in the cytoplasm to activate ethylene signaling and enhance SRBSDV proliferation;this also repels the insect vector to reduce infestation. In late infection, P6 enters the nucleus, where it interacts with OsEIL2, a key transcription factor of ethylene signaling. The P6-OsEIL2 interaction suppresses ethylene signaling by preventing the dimerization of OsEIL2, thereby facilitating viral transmission by attracting the insect vector. Collectively, these findings reveal a novel molecular mechanism by which an arbovirus modulates the host defense system to promote viral infection and transmission.

The kinetic study of light alkene syntheses by CO_(2) hydrogenation over Fe-Ni catalysts

A kinetics model of CO_(2) hydrogenation over iron-nickel catalysts was developed based on the detailed mechanism of alkenes re-adsorption and secondary reaction.The corresponding kinetical experiments are conducted in a continuous fixed bed reactor.The effect of reaction conditions on catalyst performance was analyzed according to the results of orthogonal experiments.The results of the experiments show that more methane in products can be obtained with iron-nickel catalysts,the trend of which is consistent with the thermodynamic analysis.However,the content of alkenes in products is equivalent with that of alkanes.This shows that the reaction is controlled by kinetics.In all,the results of the experiments also substantiate that the model can give a good representation of the reaction mechanism of CO_(2) hydrogenation over iron-nickel catalysts.The parameters of this model give a better explanation for the question why the iron-nickel catalysts have a higher selectivity toward alkenes compared with other iron-based catalysts.

A direct,sensitive and high-throughput genus and species-specific molecular assay for large-scale malaria screening

Background:Infectious disease diagnostics often requires sensitive molecular assays that identify at both genus and species levels.For large scale screening,such as malaria screening for elimination,diagnostic assay can be a challenge,as both the throughput and cost of the assay must be considered.The requirement of nucleic acid extraction hampers the throughput of most molecular assays.Co-amplification of multiple species or multiplex identification either can result in missed diagnosis or are too costly for large-scale screening.A genus-and species-specific diagnostic assay with simplified procedure,high sensitivity and throughput is still needed.This study aimed to develop a sensitive and high-throughput approach for large-scale infectious disease screening.Methods:We developed multi-section Capture and Ligation Probe PCR(mCLIP-PCR)for the direct detection of RNA without extraction and reverse transcription.Multiple tailed sandwich hybridization probes were used to bind at genus-and species-specific sections of the target RNA to cooperatively capture the target onto a 96-well plate.After enzymatic ligation of the bound probes,a single-stranded DNA formed at each section with distinct tail sequence at the ends.They were separately PCR-amplified with primers corresponding to tail sequences for genus or species identification.We applied the method to the active screening ofPlasmodium infections of 4,580 asymptomatic dried blood spot samples collected in malaria endemic areas and compared the results with standard qPCR using linear regression.Results:With multi-section cooperative capture but separate amplification strategy,we accurately identified genusPlasmodium and speciesP.falciparum andP.vivax without RNA extraction,with favorable sensitivities among the published reports.In the active screening,our method identified all 53 positive infections including two mixed infections,and twoP.vivax infections that were missed by standard qPCR.Conclusions:mCLIP-PCR provides a sensitive and high-throughput approach to large-scale infectious disease screening with low cost and labor,making it a valuable tool for malaria elimination in endemic region.