Recent developments in high-performance Nafion membranes for hydrogen fuel cells applications

As a promising alternative to petroleum fossil energy,polymer electrolyte membrane fuel cell has drawn considerable attention due to its low pollution emission,high energy density,portability,and long operation times.Proton exchange membrane(PEM)like Nafion plays an essential role as the core of fuel cell.A good PEM must have satisfactory performance such as high proton conductivity,excellent mechanical strength,electrochemical stability,and suitable for making membrane electrode assemblies(MEA).However,performance degradation and high permeability remain the main shortcomings of Nafion.Therefore,the development of a new PEM with better performance in some special conditions is greatly desired.In this review,we aim to summarize the latest achievements in improving the Nafion performance that works well under elevated temperature or methanol-fueled systems.The methods described in this article can be divided into some categories,utilizing hydrophilic inorganic material,metal-organic frameworks,nanocomposites,and ionic liquids.In addition,the mechanism of proton conduction in Nafion membranes is discussed.These composite membranes exhibit some desirable characteristics,but the development is still at an early stage.In the future,revolutionary approaches are needed to accelerate the application of fuel cells and promote the renewal of energy structure.

Dual RNA-seq provides novel insight into the roles of dks A from Pseudomonas plecoglossicida in pathogenhost interactions with large yellow croakers(Larimichthys crocea)

Pseudomonas plecoglossicida is a rod-shaped,gram-negative bacterium with flagella.It causes visceral white spot disease and high mortality in Larimichthys crocea during culture,resulting in serious economic loss.Analysis of transcriptome and quantitative real-time polymerase chain reaction(PCR)data showed that dks A gene expression was significantly up-regulated after 48 h of infection with Epinephelus coioides(log2 FC=3.12,P<0.001).RNAi of five sh RNAs significantly reduced the expression of dks A in P.plecoglossicida,and the optimal silencing efficiency was 96.23%.Compared with wild-type strains,the symptoms of visceral white spot disease in L.crocea infected with RNAi strains were reduced,with time of death delayed by 48 h and mortality reduced by 25%.The dks A silencing led to a substantial down-regulation in cellular component-,flagellum-,and ribosome assembly-related genes in P.plecoglossicida,and the significant up-regulation of fli C may be a way in which virulence is maintained in P.plecoglossicida.The GO and KEGG results showed that RNAi strain infection in L.crocea led to the down-regulation of inflammatory factor genes in immune-related pathways,which were associated with multiple immune response processes.Results also showed that dks A was a virulence gene in P.plecoglossicida.Compared with the wild-type strains,RNAi strain infection induced a weaker immune response in L.crocea.