Molecular and functional comparisons of the vacuolar Na^+/H^+ exchangers originated from glycophytic and halophytic species

A novel vacuolar Na+/H+ exchanger, CgNHX1, was cloned from a halophytic species Chenopodium glaucum by using reverse transcriptase-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) technique. Sequence alignment and phylogenetic analysis of 22 NHX genes from GenBank as well as the new CgNHX1 gene indicate that NHX genes shared a great degree of similarity, regardless of their glycophytic or halophytic origin. Expression of the CgNHX1 gene was induced by NaCl and peaked at 400 mmol/L NaCl. Overexpression of NHX1 genes in rice enhanced their tolerance to salt stress. However, there is no significant difference in salt tolerance among the transgenic rice plants overexpressing the NHX1 genes from either glycophytic or halophytic species. The Na+ content of both the wild type (WT) and transgenic plants increased when exposed to 50 and 100 mmol/L NaCl, and the Na+ concentration in transgenic plants was marginally higher than that of WT. Our data demonstrate that the overexpression of the NHX1 gene from either glycophytic or halophytic species resulted in the enhanced tolerance to salt stress at a similar level, suggesting that NHX gene per se might not be the reason accounting for the difference in salt tolerance between glycophytes and halophytes.

Flexible carbon fiber-based composites for electromagnetic interference shielding

With the rapid development of electronic information technology,the waste electromagnetic radiation generated by the wireless and various other electronic devices has caused serious harm to human health.The development of high-efficiency flexible electromagnetic interference(EMI)shielding materials has become one of the most effective ways to mitigate the increasingly serious problem of electromagnetic pollution.Flexible carbon fiber composites possess most of the physical requirements needed for EMI shielding applications,including high electrical conductivity,large specific surface area,light weight,flexibility,porous structure,and adjustable physical and chemical properties,and various morphology of carbon fibers-based composites applied EMI.In this review,the primary EMI shielding mechanism of carbonfiber-based materials is presented.Since carbon fiber suffers from a low absorption efficiency when used for EMI shielding by itself,it is usually combined with additional EMI filling materials.Therefore,the methods of adding EMI filler materials to the carbon fiber framework and the influence of different fillers on the EMI shielding performance are also discussed.In addition,the novel structural designs of flexible carbon fiber-based EMI shielding materials,including fiber orientation,core-shell structure,and multilayer heterostructure,are summarized in terms of their classification,which includes composites with metal,polymer,nano-carbon,and MXenes.The review concludes with a brief discussion of the challenges,research directions,and future prospects of carbon-fiber-based EMI shielding materials.