We developed organic light-emitting diodes (OLEDs) with nanopatterned current flow regions using electron-beam lithography with the aim of suppressing singlet–polaron annihilation (SPA). Nanopatterns composed of lines and circles were used in the current flow regions of nano-line and nano-dot OLEDs, respectively. Excitons partially escape from the current flow regions where SPA takes place. As such, current densities where external quantum efficiencies were half of their initial values (J0) increased as line width and circle diameter were decreased to close to the exciton diffusion length. Circles were more efficient at enhancing exciton escape and increasing J0 than lines. The J0 increase in the nano-dot OLEDs containing nanopatterned circles with a diameter of 50 nm was approximately 41-fold that of a conventional OLED with a current flow region of 4 mm2. The dependence of J0 on the size and shape of the nanopatterns was well explained by an SPA model that considered exciton diffusion. Nanopatterning of OLEDs is a feasible method of obtaining large J0.

A dibenzofuran (DF)-degrader Terrabacter sp. strain DBF63 harbors the dbfA and dbfBC genes for DF degradation and the fln-dbfA, pht, and pca gene clusters for the utilization of fluorene (FN) as a sole carbon source. From this strain, dfdA1, the gene encoding the second DF dioxygenase was detected using degenerate polymerase chain reaction (PCR) and the dfdA1A2A3A4 genes were cloned from a cosmid library of the DBF63 genome. Nucleotide sequencing revealed that the dfdA genes showed considerably high identities with those of other actinobacteria, such as Terrabacter sp. strain YK3 and Rhodococcus sp. strain HA01. In the neighboring region of the dfdA genes, as many as 11 homologs for transposase and integrase genes and the putative extradiol dioxygenase gene disrupted by an insertion sequence (dfdB::ISTesp2) were found, suggesting that repeated gene rearrangement had occurred. Quantitative reverse transcription-PCR analysis revealed that dfdA1 was expressed primarily in the DF-fed strain, whereas dbfA1 was expressed in the FN-cultured strain, apparently indicating that the dfdA genes are induced by DF for the initial hydroxylation of DF in strain DBF63. Furthermore, two polycistronic gene cassettes consisting of either dfdA or dbfA together with the dbfBC gene were constructed and expressed heterologously in Streptomyces lividans, degrading DF to salicylate. Furthermore, the expressed DfdA dioxygenase degraded dibenzo-p-dioxin, carbazole, dibenzothiophene, anthracene, phenanthrene, and biphenyl, thereby exhibiting a broader substrate range than that of the DbfA dioxygenase.

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Flexible devices produced using organic materials have attracted the attention of many researchers. Important components of these flexible devices include transparent electrodes, which transmit visible light and possess conductivity. The present study improved the characteristics of a transparent conductive film that was made of poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), an organic conductive material, and that had been prepared using ink-jet printing. To improve the resistance value and visible light transmittance of the film, the film substrate was first cleaned with ultraviolet/ozone treatment, and then the film was annealed after it was deposited on the substrate and dipped into a polar solvent. Consequently, the resistance value of the thin film decreased. However, the surface state of the film changed according to the treatment method and affected its visible light transmittance. Thus, the surface state of the film substrate, the annealing temperature after film deposition, and the dipping treatment with a polar solvent influenced the characteristics of a thin film.

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