RESUMEN
Solar cells that are semitransparent and highly efficient can find diverse applications in automobile windows, building walls, and wearable devices. Here, we present a semitransparent perovskite thin-film solar cell with an Ag nanogrid transparent electrode, where electrospun poly(ethylene oxide) (PEO) nanofibers are used as an etching mask. Directional electrospinning has allowed us to obtain a grid-shaped electrode of well-aligned Ag nanogrids. The performance of transparent electrodes can be controlled by the electrospinning conditions and the choice of substrate materials. We theoretically analyze the transmittance and sheet resistance of the electrode. Furthermore, transferable Ag nanogrid transparent electrodes are fabricated on poly(dimethylsiloxane) (PDMS) substrates for application in semitransparent perovskite solar cells. Using an electrode that shows a high transmittance (92.7%) with a low sheet resistance (18.0 Ω·sq-1), a semitransparent perovskite thin-film solar cell demonstrates average visible wavelength transmittance, power conversion efficiency, and light utilization efficiency rates as high as 25.2, 12.7, and 3.21%, respectively.
RESUMEN
Triclosan (TCS) is a widely used antimicrobial agent and TCS resistance is considered to have evolved in diverse organisms with extensive use of TCS, but distribution of TCS resistance has not been well characterized. Functional screening of the soil metagenome in this study has revealed that a variety of target enoyl acyl carrier protein reductases (ENR) homologues are responsible for the majority of TCS resistance. Diverse ENRs similar to 7-α-hydroxysteroid dehydrogenase (7-α-HSDH), FabG, or the unusual YX7K-type ENR conferred extreme tolerance to TCS. The TCS-refractory 7-α HSDH-like ENR and the TCS-resistant YX7K-type ENR seem to be prevalent in human pathogenic bacteria, suggesting that a selective enrichment occurred in pathogenic bacteria in soil. Additionally, resistance to multiple antibiotics was found to be mediated by antibiotic resistance genes that co-localize with TCS resistance determinants. Further comparative analysis of ENRs from 13 different environments has revealed a huge diversity of both prototypic and metagenomic TCS-resistant ENRs, in addition to a selective enrichment of TCS-resistant specific ENRs in presumably TCS-contaminated environments with reduced ENR diversity. Our results suggest that long-term extensive use of TCS can lead to the selective emergence of TCS-resistant bacterial pathogens, possibly with additional resistance to multiple antibiotics, in natural environments.
Asunto(s)
Bacterias/efectos de los fármacos , Farmacorresistencia Microbiana/genética , Enoil-ACP Reductasa (NADH)/genética , Metagenoma/genética , Oxidorreductasas de Alcohol/genética , Bacterias/genética , Bacterias/patogenicidad , Farmacorresistencia Microbiana/efectos de los fármacos , Enoil-ACP Reductasa (NADH)/efectos de los fármacos , Humanos , Hidroxiesteroide Deshidrogenasas/genética , Metagenoma/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Triclosán/uso terapéuticoRESUMEN
Triclosan, the widely used biocide, specifically targets enoyl-acyl carrier protein reductase (ENR) in the bacterial fatty acid synthesis system. Although the fish pathogen Aeromonas salmonicida subsp. salmonicida exhibits triclosan resistance, the nature of this resistance has not been elucidated. Here, we aimed to characterize the triclosan resistance of A. salmonicida subsp. salmonicida causing furunculosis. The fosmid library of triclosan-resistant A. salmonicida subsp. salmonicida was constructed to select a fosmid clone showing triclosan resistance. With the fosmid clone showing triclosan resistance, a subsequent secondary library search resulted in the selection of subclone pTSR-1. DNA sequence analysis of pTSR-1 revealed the presence of a chromosomal-borne fabV-encoding ENR homolog. The ENR of A. salmonicida (FabVas) exhibited significant homology with previously known FabV, including the catalytic domain YX(8)K. fabVas introduction into E. coli dramatically increased its resistance to triclosan. Heterologous expression of FabVas might functionally replace the triclosan-sensitive FabI in vivo to confer E. coli with triclosan resistance. A genome-wide search for fabVas homologs revealed the presence of an additional fabV gene (fabVas2) paralog in A. salmonicida strains and the fabVas orthologs from other gram-negative fish pathogens. Both of the potential FabV ENRs expressed similarly with or without triclosan supplement. This is the first report about the presence of two potential FabV ENRs in a single pathogenic bacterium. Our result suggests that triclosan-resistant ENRs are widely distributed in various bacteria in nature, and the wide use of this biocide can spread these triclosan-tolerant ENRs among fish pathogens and other pathogenic bacteria.
